Review Lpr Trends & Technologies for Future Lighting Solutions Sep/Oct 2015 | Issue 51

www.led-professional.com ISSN 1993-890X

Review LpR Trends & Technologies for Future Lighting Solutions Sep/Oct 2015 | Issue 51

Special: Zhaga’s Latest Books Tech-Talks BREGENZ: Andreas Weisl Graphene-Based, Spectrally Tunable, Flexible LEDs Measurement Uncertainty and Conformity

EDITORIAL 4 Celebration 15-5-50 & Exclusive Zhaga Papers

The numbers 15-5-50 stand for the three reasons we are celebrating this year; namely the International Year of Light 2015, the 5th anniversary of the LpS event in Bregenz and the 50th issue of the LED professional Review (LpR).

After celebrating the publication of LpR issue #50 in August, we are now looking forward to the upcoming LpS 2015 event which will take place in Bregenz on September 22-24. The focus of the 5th LpS is on the trends and technologies for future lighting solutions.

This year the program concentrates on the building blocks for smart lighting designs. A special Design-meets-Technology Day on September 22nd will bring architects, lighting designers and lighting planners together with experts from academia and industry. Closing the gap for understanding new technologies between these different groups could be essential for further progress because innovations are mainly driven from the directions of applications and technologies.

The LpS 2015 will open with the keynotes from Professor Zary Segall from the Royal Institute of Technology in Sweden, Rogier van der Heide, Design and Marketing Officer at Zumtobel Group in Austria and Jy Bhardwaj, CTO at Lumileds in the USA. About 60 presentations are grouped into the following sessions: Light Quality, Connectivity & Security, Reliability & Lifetime, Standardization, Light Sources, Smart Controls & Drivers, Thermal Management and Optics. There will be 7 workshops which are meant to augment comprehension in the fields of Light Measurement, Optics, Thermal Management, OLEDs, Smart Controls, Light Mixing and Automotive Lighting. You’ll find the complete program as part of this issue.

The combination of the numbers 15-5-50 also affects our view of the synergies between international lighting collaborations, lighting events and lighting publications. This view was corroborated recently when we announced our long-term strategic partnership with the esteemed Messe Muenchen, organizer of the electronica and productronica, to further strengthen and force Solid-State-Lighting topics on an international scale. I would like to take this opportunity to thank Managing Director Mr. Senger and Dr. Lechner and his team for establishing this partnership.

As an exclusive highlight, this issue of the LpR includes the latest technical articles from The Zhaga Consortium including the latest information and updates on COB modules, Driver and Module Interfaces, Thermal Interfaces and LES Considerations. Thank you to Musa Unmehopa and Tim Whittaker for this rewarding collaboration!

Further in this issue you’ll find articles about research in phosphor materials for COB modules, photometric considerations of light measurements, graphene based LED technology, chip-array technology for SMD packages, thermal management considerations of PCB designs and noteworthy facts about light-pollution.

Have a great read.

Yours Sincerely,

Siegfried Luger CEO, Luger Research e.U. Publisher, LED professional Event Director, LpS 2015

CATEGORYCONTENT OVERVIEW 6

COMMENTARY REGULARS 08 Can We Have that, Please? - What We as a Manufacturer of Lamps are Looking For 04 EDITORIAL by Axel Schmid, Ingo Maurer 08 COMMENTARY 10 PRODUCT NEWS TECH-TALKS BREGENZ 26 RESEARCH NEWS 34 EVENT NEWS Andreas Weisl, SSC Europe, Vice-President 42 36 IYL 2015 NEWS compiled by Siegfried Luger, LED professional

RESEARCH 30 PRODUCT LAUNCHES AT LpS 2015 Al O Coated Europium-Activated Aluminum Silicon 48 2 3 38 LpS 2015 FINAL PROGRAM Nitride for COB LED Technology 110 ABOUT | IMPRINT by Nika Mahne et al., Graz University of Technology 58 A Graphene-Based, Spectrally Tunable, Flexible Field-Effect Light-Emitting Device by Xiaomu Wang & He Tiany et al., Tsinghua University

QUALITY

70 Measurement Uncertainty and Conformity Assessment in Photometry SPECIAL: ZHAGA by Peter Blattner, METAS & European Association of Metrology Institutes 90 Latest Books written by various Zhaga members TECHNOLOGIES

78 Chip Arrays in SMD Packages - A New Class of LEDs by Ralph Bertram, Osram Opto Semiconductors 84 Mastering Thermal Issues in LED PCB Design & Laminate Selection by Martin Cotton, Ventec Europe

SPECIAL: ZHAGA’S LATEST BOOKS 91 Zhaga Evolves: Focus on Component Standardization Drives New Book Development LEADING ARTICLE by Musa Unmehopa & Tim Whitaker, Zhaga Consortium 70 Measurement Uncertainty and Chip-on-Board LED Modules Standardized in Zhaga Book 12 96 Conformity Assessment in Photometry by Martin Creusen & Charles Knibbeler, Philips Lighting; Manfred Scheubeck, by Peter Blattner, METAS & European Osram Opto Semiconductors; Ingo Arnrich, BJB; Nico van Stiphout, Molex Association of Metrology Institutes 100 Light-Emitting Surface (LES) Concept Enables Comparison of Photometric Properties by Stefan Lorenz, Osram GmbH 104 Zhaga Determines Thermal Fit of LED Light Engines and Luminaires by Uli Mathis, Tridonic; Toine Staring, Philips Lighting 106 DMI Specification Defines Electrical Interface between LED Drivers and Modules by Arnulf Rupp, Osram

ADVERTISING INDEX

FUTURE LIGHTING SOLUTIONS 1 GLOBAL LIGHTING TECHNOLOGIES 22 UNDERWRITERS LABS 57 LUMILEDS 2 VOSSLOH-SCHWABE 23 REFOND 61 INFINEON 3 IMOS GUBELA 24 INPOTRON 63 DOW CORNING 5 FISCHER ELEKTRONIK 25 BARTHELME 69 DIGI-KEY 7 ELLSWORTH ADHESIVES 26 EDISON 73 LPS 2016 9 EUROLIGHTING 26 GRAFTECH INTERNATIONAL 75 ESCATEC 11 KDG OPTICOMP 27 ALITE 76 SHINYU LIGHT 12 INFINEON WEBINAR 28 CREE 77 AUER LIGHTING 13 THE BERGQUIST COMPANY 29 IDEAL INDUSTRIES 81 ELECTROLUBE 14 DIGI-KEY 29 CERAMTEC 82 CARCLO 15 TE CONNECTIVITY 33 LED EXPO DELHI 83 FUHUA 16 LPS 2015 37 INTERLIGHT MOSCOW 87 LEXTAR 17 AUER LIGHTING 46 HKTDC (AUTUMN EDITION) 89 GL OPTIC 19 HONGLITRONIC 47 LUGER RESEARCH 109 VENTEC 19 FUTURE LIGHTING SOLUTIONS 51 LED PROFESSIONAL REVIEW 111 INSTRUMENT SYSTEMS 20 FUTURE LIGHTING SOLUTIONS 53 WAGO 112 LEDLINK 21 FUTURE LIGHTING SOLUTIONS 55

CAN WE HAVE THAT, PLEASE? WHAT WE, AS A MANUFACTURER OF LAMPS, ARE LOOKING FOR

Many things have happened CRI. This can be found more Axel Schmid since the blue and the white and more, especially with LEDs Axel Schmid works as a LEDs were introduced to the meant for ambient light output. designer for Ingo Maurer market. It was, and still is, But for lighting a room for living, an exciting time for us as a you also need small and powerful GmbH, a company in manufacturer of lamps spotlights with narrow beam Munich, Germany. and light objects. angles and without multi They design, develop and shadows. This seems to be produce lamps, light objects Of course Solid State the field for flashlights, Technologies often tries to where output is the highest and interior spaces. substitute traditional light goal that subordinates the He studied industrial design technologies (and is doing quite quality of white. at the Staatliche Akademie well in some cases), but when der Bildenden Kuenste there are possibilities to make Or we want to modulate light in light broader - that’s where it a certain way, not predefined or in Stuttgart under starts to get interesting for us. specified. Rigid systems spoil Prof. Klaus Lehmann and We appreciate the small form the varieties, modular set-ups Prof. Richard Sapper. factor of LEDs and the thinness help to adjust and fine-tune After his graduation he of OLEDs, for example. But often the outcome. the design of structures and received a scholarship for necessary components diminish So in the end, even when the Japan from the German the advantages, e.g. a heat sink, supplier market gets bigger and Industrial Design association that adds volume to the back of broader, we still have to watch VDID. He has received an LED. It makes sense to find a what’s going on at the cutting classification and standardization edge of SST developments, various awards, one of so that development time is not be alert and constantly willing which was the Bavarian wasted but where diversity isn’t to tinker (in its best sense) and State Award for young eliminated. It is compulsory in experiment. In addition to that, designers. One of his a competitive market to focus we’re always happy to find a on sales figures and listen to supplier to team up with for designs for Ingo Maurer the needs of the masses, development and customization is part of the permanent but we need to save the (having a stake in big ideas collection at the niches and extremes. rather than in big amounts). Museum of Modern Art In a sense this also applies to And of course one is never in New York City. technical data, which improves satisfied. As soon as the next continuously but still has a innovation is introduced, our long way to go. imaginations are captured. It is indeed an exciting time Because we generally produce for us and will continue to be light fixtures for residential so in the future. spaces, we always seek a high A.S.

NEWS PRODUCTS 10

Osram Presents New The launch of the “Brilliant Color” and the Giuliano Cassataro, Plessey’s VP Global Soleriq S 19 Version CRI 80 and CRI 90 versions is scheduled for Sales, said, “We are seeing a definite move mid of August 2015. The Soleriq S 19 with away from discrete PLCC designs, especially with Higher Efficacy CRI 70 will be available by the end of the in the higher power applications. By having Osram Opto Semiconductors complements year. The certification process based on the our own growth and semiconductor its Soleriq S 19 portfolio: The new “Brilliant LM-80 standard (Energy Star) is in progress. processing facility in Plymouth, Plessey Color” LED is especially designed for retail The results for 3,000 and 6,000 hours are provides the flexibility and speed of response and shop lighting applications as it features a already available; the results for 10,000 hours required for a vast range of high-end high color quality which is very similar to that are expected by year-end. applications that can use the thermal and of high intensity discharge lamps (HID). light output from our silicon LED die.” This enables rich and saturated colors and provides a high quality of white. They also Plessey offers its range of blue die in launch product versions with an increased Plessey Releases New various wavelength options. Capable of efficacy of up to 15%, depending on the type. Range of GaN-on-Si generating over 60% light output efficiency, LED Dies sometimes referred to as wall plug efficiency (WPE), the die are supplied to a Plessey announced the release of its range standard thickness of 150 μm, whilst other of MaGIC™ LED die, manufactured on the thicknesses can be supplied, down to a company’s patented GaN-on-Silicon minimum of 75 μm. technology. The blue die, sometimes referred to as blue pump for their ability to pump The die are supplied on a blue tape in single phosphor to a white color range, are the latest intensity and color bins to provide close innovation in high brightness LED die designed uniformity, and are intended to be used with for a wide range of medium to high power standard pick and place machines. Samples applications including general lighting, signage, are available in a variety of die pack formats Optimal LED for shop lighting: The Soleriq S 19 “Brilliant Color” enables the colors of commercial, residential and street lighting. with blue die wavelengths ranging from illuminated objects to look more saturated 420 nm to 480 nm and from mille watts to 10 watts with the PExS4500 range having a With its new Soleriq S 19 “Brilliant Color” typical optical output power of 4000 mW Osram Opto Semiconductors has managed from a 3 A drive current. to optimize the spectrum of the light source. The increased color gamut, together with the typical CRI of 85 ensures a good rendering of colors. This superior color quality originally Plessey Offers LED is a key feature of high intensity discharge Filament Modules Using lamps (HID) and, until now, has been barely the MaGIC™ Die seen as a characteristic of LEDs. As the color Plessy’s new GaN-on-Silicon LED dies appears more saturated, the new LED can include a 4.5 mm high power LED die and Plessey announced the launch of its range of emphasize and create an appealing a 1 mm die for 350mA LED filaments, manufactured with the appearance of commercial products. company’s MaGICTM GaN-on-Silicon LEDs. Together with its features like small size, Plessey CTO, Dr. Keith Strickland, said, The filaments are designed for the surging directed light distribution, no heat radiation “We have developed a wide range of LED filament bulb market where the replacement directly to the objects, minimal infrared and die for a number of applications and our lamps have far better performance, but still no UV radiation as well as long lifetime, GaN-on-Silicon technology works particularly maintain the physical appearance of it is an ideal solution for retail and shop well in higher power applications such as incandescent lamps. lighting applications where products have to high bay, street lights, projector lamps, look as good as possible. spot lamps and floodlighting. This current process technology will become the base for The three additional new versions of the our application specific LEDs, the ASLED, Soleriq S 19 with CRIs of 70, 80 and 90 can which bridges the gap between LED be implemented in spot lights, professional component suppliers, solid state lighting downlights and general indoor lighting fixture designers and the OEMs.” applications. With color temperatures between 2700 and 6500 Kelvin they offer The manufacturing process produces a warm white and cool white light for different vertical LED structure which has the anode lighting solutions. The substrate size of as bottom contact and the cathode formed Plessey’s PLF series of filaments come in a all versions is 24.0 x 24.0 x 1.4 mm, in the top metal layer. The layout of the top variety of lengths, light output and color the operating temperature ranges between metal layer is optimized for a particular LED size temperatures (CCT) from very warm -30° C and 105° C and the junction and die operating current, and includes one or 2200 K to 6500 K temperature goes up to 125° C. more bond pads for connecting to the cathode.

The traditional tungsten incandescent light Cree’s new XLamp® “We’re excited that the XHP35 LED brings bulb has been phased out in favor of LED XHP35 LEDs - The New the performance of Cree’s Extreme High technology providing the most reliable and Power LEDs to the XP footprint,” said Jorge efficient lighting solutions. Plessey’s Chip- Performance Standard Fraile, CEO, Hispaled. “In addition to On-Board LED filaments create the same for High Power LEDs delivering an impressive amount of light, amount of light, while consuming less energy the XHP35 LED allows us to leverage and offering longer life and utilize its patented Delivering 50% more light output than the existing drivers to achieve the full MaGIC™ GaN-on-Silicon technology. previous industry best, the XHP35 LED performance of Cree’s high power LEDs introduces Cree’s breakthrough 12 V at lower drive currents.” The LED filaments are designed with unique monolithic power die, empowering terminations so that they can be handled and manufacturers to unleash the full capacity Unlike other existing high power LEDs, spot welded by existing high volume fully of extreme high power LEDs using existing the XHP35 family of LEDs uses a new 12 V automated glass lamp manufacturing lines. drivers. Available in high density and high monolithic power die to deliver extreme high In addition to that, Plessey has incorporated intensity versions the new XHP35 LED delivers power performance at drive currents at or a bespoke approach to controlling the up to 1,833 lumens. Offered in CRI 70, 80, less than 1A, making the use of high power current and Vf of the filaments when the and 90 and CCT from 2700 K to 8300 K LEDs more accessible for lighting designers. filaments are driven in a bridge configuration. with 2-step and 3-step EasyWhite® options. This breakthrough is uniquely enabled by Cree’s SC5 Technology Platform built on Plessey’s CTO, Dr. Keith Strickland, said, Cree’s industry-leading silicon carbide “We have taken our existing Chip-Scale- technology and features significant Packaging technology, also used for our advancements in epitaxial structure, chip dotLEDs, into a revised format for the architecture and an advanced light filament. Not only do we have an conversion system optimized for best improvement in terms of manufacturability thermal and optical performance. with GaN-on-Silicon and enhanced the power control for filament resistors, The XHP35 LEDs are available in high density but Plessey will also be incorporating other and high intensity versions that are optimized active and passive electronic components for to deliver the maximum performance for Cree’s new XHP35 family sets a new Chip-On-Board and Chip-Scale-Packaging performance standard for high power LEDs specific applications. The XHP35 High solutions in next generation of filaments. Density LED delivers new levels of light

output in the compact XP footprint for high Edison Opto Introduces In addition, for the 5630 package product, lumen applications, such as outdoor and High Efficiency 2835 Edison Opto introduces the advanced PLCC high bay lighting. The XHP35 High Intensity 5630B HE Series which has higher efficiency LED is optimized to deliver maximum and 5630B Series (188 lm/W @ 4000 K) and greater brightness candela through secondary optics to boost Edison Opto has been striving to introduce (it reaches 34 lm @ 65 mA, 4000 K) than the performance and reduce size for applications more high efficiency products in order to previous products, providing customers with requiring high light intensity, such as strengthen its market position. One of its new a better and brighter lighting environment. stadium, torch and track lighting. advantaged products is PLCC 2835 HE The slim size of PLCC 5630B HE series Series. It features ultra-high luminous makes it flexible to be used in a variety of “Cree continues to redefine the performance efficacy (181 lm/W @ 4000 K) and compact applications such as commercial lighting, of high power LEDs. The XHP35 LED package size which increase the flexibility in residential lighting and hospitality lighting. represents a breakthrough that goes well lamp design and expand the range of beyond the incremental advances of other applications. With the outperforming LED suppliers,” said Dave Emerson, efficiency, PLCC 2835 HE Series is optimized vice president and general manager for to be used in high-end LED markets such as Lumileds Launches the Cree LEDs. “Now, more than ever, boutique and luxury apparel stores. LUXEON 3535L Color manufacturers will be able to tap the full Line for the Perfect power of extreme high power LEDs to forge lighting designs that were previously Color in any Situation thought to be impossible.” Lumileds launches the LUXEON 3535L Color Line, giving builders of emergency Samples of both XLamp XHP35 and vehicle lights, signs, color tunable bulbs XHP35 High Intensity LEDs are available and architectural lamps access to high now, and production quantities are available quality, single color mid power LEDs in with standard lead times. The XHP35 Red, Red-Orange, Phosphor-Converted LEDs are available in 70, 80 and 90 CRI (PC) Amber, Lime, Green and Blue. and color temperatures ranging from 2700 K “The tremendous success our customers Brighten your stores with the advanced PLCC to 8300 K with 2-step and 3-step HE Series which has higher efficiency and have had with our high power color emitters EasyWhite® options. greater brightness; providing your customers convinced us that multiple markets could with a better shopping environment benefit from similar colors in the mid power

performance range” said David Cosenza, Another standout product in the line is the Lumileds - Performance Product Manager for the LUXEON 3535L LUXEON 3535L Lime LED, which makes Upgrade Across the Color Line. color-changing bulbs, such as the Philips hue, much more affordable. “When mixed LUXEON CoB Core Range with Red, Lime’s unique color point enables Continuing to roll out chip-on-board (CoB) much warmer White light to be created than LEDs with ever higher efficacy and flux Off-White plus Red combinations,” said combinations, Lumileds today introduces the Cosenza. The LUXEON 3535L Lime LED next generation LUXEON CoB Core Range. features a typical flux of 56 lumens (100 mA, With the Gen 2 products, LUXEON CoB Core 25˚C) and a stellar efficacy of 190 lm/W. Range now delivers an average of 10% higher efficacy and 10% higher flux with a The LUXEON 3535L Color Line demonstrates lower voltage and the same footprint, making the increased flexibility of the Lumileds color it especially attractive to lighting designers. From the PC Amber used in warm dimming family through smaller lumen offerings. lamps to the Lime used in color-changing With the LUXEON 3535L Colors, current bulbs, the LUXEON 3535L Color Line delivers Lumileds customers looking to broaden their high quality color in a proven, reliable package product line can realize the perfect amount of color every time, no more, no less - even One product from the LUXEON 3535L Color using the same optics as the LUXEON Rebel Line is the LUXEON 3535L PC Amber LED, Color LEDs and LUXEON Z Color emitters to which can replace three 2200 K LEDs in a quickly take their new products to market. warm dimming lamp while also delivering best-in-class flux and best-in-class hot/cold The addition of the LUXEON 3535L Colors to factor (flux at 85˚C relative to flux at 25˚C). the existing LUXEON 3535L White LEDs Lumileds delivers even better options for The result is higher lm/W and lm/$ for creates the most comprehensive mid power designers of spotlights and downlights, creators of warm dimming bulbs. family on the market. bringing 10% higher efficacy and unmatched “punch” to its range of chip-on-board LEDs

“We are seeing tremendous demand in the For ease of upgrade, the LUXEON CoB Core Previous generation multicolor chips feature retail and hospitality markets, where our Range (Gen 2) products are fully compatible only red, blue and green (RGB) chips, award-winning* CrispWhite Technology really with Lumileds first generation of CoBs. combining to create a poorly integrated shines. These applications require not just white color. By adding a discrete white chip, the best quality of light, but the cost the white color is substantially brighter and effectiveness that goes with an LED solution more balanced, when compared to that of with up to 150 lm/W efficacy,” said Eric Senders, Diode Dynamics RGBW old technology. LUXEON CoB Product Family Director. LEDs for Automotive The company is now utilizing these For example, designers who implemented Diode Dynamics, has taken a major step components in a full line of LED products for the LUXEON CoB 1208, which has a forward in automotive lighting technology, by automotive applications. By upgrading light-emitting surface (LES) of 15 mm, are designing and manufacturing the first factory-installed LED lighting with the upgrading lumen output from 3,600 to products using brand-new LED components, replacement products, vehicle owners can 4,000 lumens with a 10% higher efficiency. featuring an independent white chip in achieve multicolor functionality along with Alternatively, if the same output is addition to multicolor functionality. a crisp and pure white output. maintained, efficacy can be boosted from 115 lm/W to 140 lm/W with the Gen 2 LEDs. Paul McCain, founder of Diode Dynamics, is looking to build upon his company’s Lumileds is offering the LUXEON CoB Core reputation for innovation by implementing Range (Gen 2) LEDs in multiple lumen this technology. “With the incredible packages from less than 1,000 lumens for versatility of these LEDs, I’m confident that MR16 and PAR lamps, up to 7,600 lumens they’ll be standard on all vehicles within a few for 100W CDM replacements. Color options years. By being the first to apply this exciting include the popular 2,200 K for a candlelight new technology, we will continue being ambiance and very efficient 90 CRI parts for recognized as the go-to source for innovative high quality of light. Diode Dynamics’ RGBW LEDs are especially automotive lighting products.” designed for automotive applications

The LEDs cover a wide range of color rendering indices (CRI) and correlated color temperatures (CCT), making them ideal for various indoor and outdoor applications. They are tested under hot conditions (85° C), a temperature that is close to the operating conditions in customer applications.

Oslon SSL LEDs with a minimum CRI of 90 (2700 K to 4000 K CCT) are an ideal choice for spotlights for professional indoor lighting applications in shops or museums, for stage, accent and effect lighting as well as for retrofits and fixtures. The product versions In addition to Universal’s current 80 CRI modules, the 90 CRI option will nearly double with a CRI of 80+ (2500 K to 5000 K CCT) the available selections of Everline ZH and are suitable for applications such as high Everline ZHL families on the market bay, low bay and PAR lamps. The minimum CRI of 70 (3000 K to 6500 K CCT) addresses the needs of industrial and outdoor lighting. “We are extremely proud to be launching the 90 CRI line,” said John Ronk, LED product The new Oslon SSL products are 100 manager at Universal Lighting Technologies. percent compatible with existing versions as “We are confident in the quality and reliability they share the same footprint of only of the product, with our long history of control 3.0 x 3.0 mm. This results in high-density manufacturing experience in North America. space-saving arrays and simplifies color The continuous growth of the Everline family mixing. Two different viewing angles of 80° of LED driver and module components (Oslon SSL 80) and 150° (Oslon SSL 150) positions us at the forefront of LED give customers an additional choice in technology and design application flexibility.” creating customized lighting solutions. The low thermal resistance of 4.2 K/W Universal has also launched new connector ensures cool running and high energy options for the 32 and the 56 Everline efficiency. Both new Oslon SSL types can be modules. These connector options are for driven up to 1 ampere (A). Oslon SSL LEDs end-to-end, series or parallel wiring. Osram Opto Improves deliver high reliability and performance, Standard, single connector models can be Oslon SSL 80 and SSL and the high efficiency needed in professional wired in series, while the dual connector 150 High-Performance indoor and outdoor lighting applications. driver can be wired at either end of the module to prevent shadowing in the middle LEDs of the fixture. Osram Opto Semiconductors has unveiled the new generation of Oslon SSL 80 and SSL Universal Announces 150 with proven reliability and outstanding Zhaga Compliant Everline GlacialTech Announces efficiency. These new LEDs offer improved CRI 90 LED Modules performance and low thermal resistance, 120 W LED Flood Light thereby extending the range of operating Universal Lighting Technologies announces Heatsink Kit for High conditions in customer applications. a 90 Color Rendering Index (CRI) option for its Everline® Zhaga Hybrid (ZH) and Zhaga Output LED Lighting Hybrid Low (ZHL) Linear Modules. The 90 CRI GlacialTech, the diversified LED technology option produces a vibrant color rendering that provider, announces a new 120 W heatsink creates a crisp visual and better lighting kit for outdoor flood lights. The Igloo SS120 solution. Everline modules are designed for features an efficient heatsink with thermal use in high performance lighting fixtures with resistance of just 0.34°C/W and includes a features that include high efficacy, excellent mounting bracket with 90 degree adjustability. lumen maintenance and consistent color. A glass lens accommodates CoB LEDs and a waterproof LED cover is available for Everline LED modules are available in linear outdoor applications. Besides the default and round configurations for a variety of single unit kit, the Igloo SS120 also comes in The powerful new generation of Osram Oslon SSL LEDs integrated in spotlights for lighting fixture styles. Everline modules are double, and triple unit configurations for up professional indoor lighting offered in both indoor and outdoor LED to 360 W of LED illumination, allowing easy lighting applications, and they are available in installation of high output lighting for stadiums, a large variety of lumen options. parking lots, and outdoor lighting applications.

GlacialTech’s new Igloo SS120 heat sink can be configured to support applications with up to 360 W of LED illumination

Igloo SS120 Specifications: • Part Number: CT-SS120000AB0001 • Dimension (mm): 370x132x60 • Weight (g): 1720 • Material: AL6063+AL1050 • Color: Black • Surface Treatment: Black Anode • Crafts: Stamping + Bonding • Thermal Resistance (°C / W): 0.3417 • Surface Area (mm²): 1047000 • Reference Design Power (watts): 120 W

Igloo SS120Features: • Rated for 120W CoB or MPCB LEDs • 0.34 °C/W thermal resistance • 90° adjustable mounting bracket included • Available in single, double, and triple unit configurations up to 360 W • Waterproof LED cover available • CoB LED lens available

Strong Thermal Performance for High Output LEDs: GlacialTech’s experience in thermal design allows it to create a heatsink boasting 0.34°C/W using stamping technology. The efficient thermal performance means high output CoB or MPCB LEDs up to 120 W can be accommodated.

Up to 360 W of LED Lighting for Outdoor Lighting: The Igloo SS120 heatsink kit can be ordered in single, double or triple unit options. Up to 3 floodlights, each on its own adjustable bracket can be connected together for easy installation of high output lighting needs. With each module rated for 120 W, a total of 360 W of powerful LED flood lighting can be grouped as a triple unit array.

Complete Knock Down (CKD) Lighting Versatility: The Igloo SS120 includes heatsink module, adjustable mounting bracket with 90-degree rotation, and optional lens or LED cover. Lighting installers can choose the appropriate LED luminaire and driver for their lighting needs and easily create high performance outdoor lighting with dependable GlacialTech thermal technology.

Fischer Elektronik for or screws. Mechanical treatments, custom transfer easily and dissipate quickly but also Cool LEDs designs and surface finishes can also be provide a trustworthy bond. They consist of provided for your specific application. an acrylic adhesive which contains thermally That the LED has already established itself conductive ceramic particles which transmit as the light source of the future in many heat away from sensitive components. areas is sufficiently well known and hardly in doubt. Innovative heat dissipation concepts Techsil - New Heat Providing excellent thermal coupling between for cooling it are hence more urgently Transfer Tapes for components and heat sinks - their foam-like, needed and sought-after than ever before to Thermal Management in compliant interface means that they fill any utilize its advantageous properties with true air gaps, thereby reducing the thermal efficiency and for a particularly long service Electronic Systems resistance at the interface and can life. In this regard, Fischer is expanding its Heat is often the enemy of performance n accommodate materials of different comprehensive LED cooling product range today’s intricate electronic systems, coefficients of thermal expansion. These by three further active solutions. Techsil’s new thermally conductive, pressure double-sided tapes can be used in place of sensitive adhesive tapes provide a cooling mechanical fasteners and are designed for solution by efficiently transmitting heat away bonding heat sinks on PCBs, LED strips and from sensitive components. These double- IC packages, mounting of ICs, GPUs, heat sided tapes are designed for bonding heat pipes and heat sink assembly. sinks on PCBs, LED strips and IC packages, mounting of ICs, GPUs, heat pipes and for Along with high thermal conductivity, Stokvis heat sink assembly. 202331 and 202332 also offer good heat resistance, age resistance and weatherability. These white, flame retardant acrylic foam tapes are halogen free and perform at intermittent temperatures of up to 150°C, Fischer’s new LA LED 40x30, LA LED 50x20 and LA LED 50x45 active cooling series with a continuous service temperature range of -40°C and +105°C - which means that electronic components can perform at the The product series LA LED 40x30, LA LED upper limits of their operating range for 50x20 and LA LED 50x45 consists of a pin longer periods of time. heat sink and a round fan motor that has been specifically conceived for active LED Here’s the Technical bit: Techsil’s two new thermally conductive tapes cooling. The fan motor has a double slide consist of an acrylic adhesive which contains The thermal conductivity offered by Stokvis bearing and is designed for the particular thermally conductive ceramic particles. This 202331 is 2 W/mK, with a breakdown voltage requirements of LED applications in terms of guarantees excellent thermal coupling for the of 35 kV/mm. It offers high adhesion on noise and service life. It is screwed to the top tape that also provide a trustworthy bond stainless steel and a static shear (@ 23°C) of of the pin using internally threaded distance 1 kg/625mm2. This grade comes in a 0.5 mm sleeves that are provided for this purpose. Benefits of Tapes as TIM: thickness as standard, however if you’re • Clean: No mixing, dispensing or cleaning looking for a thicker alternative try Stokvis With their special arrangement and high • Fast: The strip and stick solution will 202332 which is 0.8 mm thick. It still offers number of pins, the compact pin heat sinks increase output and minimize waste, it is a high thermal conductivity of 1.2 W/mK, are designed for optimal air throughput. easy to apply. As tape is a completely dry with a higher adhesion to steel. Thanks to the properties of their materials, system there is no waiting around for it to their geometry and structure, these pin heat cure, saving time sinks are extremely efficient coolers for • Safe: Your Health & Safety department will electronic components in free convection, be thrilled; there is no risk of spill, no mess Litecool Black X™ - but particularly also in forced convection. and no hazardous nasties within the New Dielectric Material for product composition to deal with Thermal Management The aluminum alloy used (Al99.5) has very • Reliable: The length, width and thickness good heat conductivity. In addition, the will result in a controlled thermal path Litecool has produced LED packages using manufacturing process serves to create a • Cost Effective: Can replace mechanical a new dielectric material that has a thermal homogenous material arrangement and fixtures conductivity of 1000 W/mK - 3 times higher microstructure that follows the direction of • These gap filling foam tapes also come than copper and 30 times better than alumina the heat flow - all of which ensures fast and with the added benefit of providing ceramic. Dielectrics are used within LED even heat distribution in the heat sink vibration insulation and restricting any packages to isolate electrical tracks but they bottom and fins. unwanted movement or slippage hinder the thermal path causing the LED to overheat. Mid-lower, low cost LED packages The LEDs can be fastened to the pin heat Techsil are excited to introduce two new use plastic as the main dielectric material. sink with thermally conductive adhesive, thermally conductive tapes (Stokvis 202331 High-power, high cost LED packages use double-sided thermally conductive foil, and 202332) which not only allow heat to ceramics such as alumina as the dielectric.

Litecool claims Black X™ to have a thermal conductivity 3 times higher than copper and 30 times better than alumina ceramic

Litecool has successfully prototyped and tested LED packages using Black X™, offering a thermal conductivity 30 times higher than alumina, as the dielectric. The LED packages have a thermal resistance of between 0.2 ⁰C/W and 0.5 ⁰C/W depending on the construction. This is up to 6 times lower than the closest competitor which means the LED can be powered with 6 times more current without overheating.

“It is an incredible material. We have always assumed dielectric materials will hinder the thermal performance of our LED packages but this material actually improves it. The thermal resistances of the LED packages we have made are so low we had trouble measuring it. We had to use 9 high power LEDs in one package to give enough power density to record any difference in temperature,” says Robert Corbin, Project Engineer at Litecool.

“This is a step change in the performance of an LED package. We will be able to hit new lumen density thresholds without the need for costly heat sinks, heat pipes or fans. We see this material initially being used in spot light applications for pin-point light sources but we also intend to incorporate it into our Lumen Block for the wider LED lighting market,” Litecool’s CEO James Reeves is convinced.

Mean Well Introduces voltage output. This series adopts a New Price-Effective fanless design; with the high working efficiency greater than 91%, it can work High Voltage, High between the ambient temperature Power LED Power -40~+70°C under free air convection. Supply Series ELG-150-C offers multiple function options, dimming functions and IP Mean Well has been involved in the LED protection levels that can perfectly satisfy power supply field for years. Many the design flexibility for lighting fixture models, such as CLG, HLG and HLG-C designers (please refer to the table under series, with the supreme product Order Information). specification and high reliability, have been extensively exploited in various ELG-150-C fits all kinds of LED luminaire kinds of outdoor or indoor luminaire applications, such as LED street lighting, applications. In order to cope with the LED harbor lighting, LED bay lighting, intense competition in the LED lighting LED greenhouse lighting, etc. It is market, Mean Well is now introducing the expected to be an extremely popular ELG family, the optimal price- power supply product once launched into performance ratio model with highly the market. competitive pricing.

Thomas Research Products Introduces New PLED60W High- Performance LED Driver Thomas Research Products has added the new PLED60W to the PLED series of high-performance LED Drivers. And with Mean Well’s ELG family comprises 75 W it, the entire PLED line is now UL Type HL through 240 W LED power supplies with high performance at reasonable cost rated for use in hazardous locations. Thomas Research Products manufactures complete SSL power solutions. Main Features: • 180-295 VAC input • Constant Current (C.C.) output • Built-in active PFC function • High efficiency up to 92% • Working temperature: -40~+70°C • Protections: Short circuit / Over current / Over voltage / Over temperature • Comply with harmonic current limit per EN61000-3-2 Class C (@50% load) • Meet 6kV surge immunity level TRP’s new PLED60W LED driver offers (EN61000-4-5) similar features and better performance than its predecessor while being 25% smaller • Approvals: UL / CUL / ENEC / CB / CE • Type “HL” for use in class I, Division 2 hazardous (Classified) location All PLED series drivers, including the luminaires PLED60W, now feature Type HL rating by • Metal case, dimension ( L x W x H ): UL. The design is robust enough for use 280 x 144 x 48.5 mm in Class I Div 2 Hazardous Location • 5 years warranty luminaires. Even though not all applications require this rating, it provides The ELG family comprises the wattage OEMs assurance that these drivers will from 75 W through 240 W. All of the perform in a variety of environments. models operate for the input range 180-295VAC. ELG-150-C is the first TRP’s PLED series drivers offer the series that is announced - a 150 W power features for which the company is known, supply with constant current and high including Black Magic Thermal AdvantageTM

NEWS PRODUCTS

aluminum enclosures. To keep luminaires This new LED driver demonstrates performing, they offer over-voltage, ROAL’s continued commitment to bring over-current and short circuit protection value to the lighting industry. Seven years with automatic recovery. They are also ago ROAL introduced the most compact IP66 rated for dry and damp locations, LED drivers in the market, enabling and come with a 5 year warranty. lighting designers to create smaller and more elegant fixtures. Now the lighting market benefits with the industry’s first ROAL’s New MESO multi-unit RFID programmable platform. 50W Offers RFID Wireless Programming Lambda Research ROAL Electronics SpA announces the Releases TracePro® release of its newest programmable LED Version 7.6 Update driver series, MESO 50, featuring the wireless programmability. This new RFID Lambda Research Corporation, a leading technology offers measurable benefits by designer and publisher of illumination and enabling simultaneous feature set optical design software, announces the programming of multiple devices without current release of the latest version of its the need to turn on the unit, or to remove flagship TracePro software. the product from its packaging.

The only “all-in-one” 50W driver platform Lambda Research’s latest version of available with compact size, WW Input, TracePro® has implemented several new Multi-Unit Wireless Programmability and features and material catalogues Multiple Dimming - Suitable for indoor, outdoor and architectural applications The latest release, TracePro v7.6, Providing 50 watts of power in a very includes the capability to create repetitive compact size (105 x 73 x 27 mm / features on curved surfaces, new diffuser 4.13 x 2.87 x 1.06 in), with worldwide AC catalogs, new macro editor and a input voltage range (120/230/277 VAC) or simplified menu structure that optional DC power input and the broadens the program’s capabilities. industry’s first multi-unit wireless The BrightView, Bayer Makrolon®, programmability feature, MESO 50 and Luminit diffuser sheet catalogs are reduces design time, lead time, and part now available as surface property numbers to stock while increasing catalogs in the TracePro v7.6 optical designer flexibility. properties database. TracePro’s Source Editor has been expanded to operate on This flexibility is demonstrated by MESO Grid and File sources. The incident ray 50’s unique multiple dimming options, table now includes Optical Path Length including Analog 0 - 10V, Digital control via information for each ray. The solar utility either DALI or PWM, and Push Dimming. has been enhanced to add multiple solar tracking solutions and to calculate MESO 50 ensures universal adaptability turbidity over a period. and delivers many advanced features such as lower THD <20%, PF > 0.9 TracePro’s revised texture utility creates at any nominal input voltage and 5kV any type of repetitive geometry feature Surge Protection. It is also suitable and textures on curved surfaces. for harsh environments up to 90°C This new feature is perfect for modeling case temperature. curved displays especially ones using scattering features. The solid geometry

created is fully customizable allowing optimization by the utility to create uniform displays. Users can specify spacing, feature type and cell layout using the utility to texture any curved or planar object.

A new Scheme macro editor has been added, Notepad++© to provide users with a powerful editing component. This new editor provides Scheme macro syntax highlighting, multi-document support, auto-completion, and macro launch directly from the editor.

Additionally, TracePro’s menu structure has been simplified to create a more logical workflow by moving utilities into the correct menu placements. Menus have been kept one level deep to create a simple menu structure creating the easiest to use optical product on the market today.

TracePro offers the most powerful and sophisticated illumination design software available for LED implementation into lamps and luminaires. TracePro streamlines the prototype-to-manufacturing process by combining an intuitive 3D CAD interface, superior ray-tracing performance, advanced utilities, and seamless interoperability with other mechanical design programs.

Konica Minolta - New Compact, Easy to Use CRI Illuminance Meter

The CRI Illuminance meter CL-70F is a compact, lightweight, handheld entry-level instrument for measuring the color and illuminance of light sources (including new LED and EL light sources). Measurement data is displayed in terms of CRI, tristimulus values, illuminance, chromaticity, dominant wavelength, excitation purity, correlated color temperature, and difference values from a target.

Konica Minolta’s new CL-70F CRI Illuminance Meter provides easy measurement and display of CRI, CCT, chromaticity, spectral information and gives a quick overview of all relevant values

Main Features: • Spectral sensor with a measuring range of 380 nm - 780 nm • Measure Color Rendering Index (CRI) with a comprehensive color bar graph • Compact, easy to carry and battery operated • Color touch screen for graphical and numerical display of measurements

The sleek instrument is designed for a variety Additional features provided by included CIE1931 XYZ Colorimeter board for color of common lighting tasks including lighting Utility software CL-SU1w: testing applications design and ongoing maintenance. Providing With the software CL-SU1w which is included The sensor system is based on the spectral information and CRI measurement as a standard accessory, you can modify JENCOLOR® standard components the CL-70F provides entry level access to instrument settings, store & group data and MTCSiCF (True Color sensor) and MCDC04 cutting edge light measurement features. make further analysis of the measured data. (Signal converter). The sensor is based on Combining the instrument with a flash sync the CIE1931 XYZ color standard, while the cable enables spectral measurements of flash The CRI Illuminance Meter perfectly fits into signal converter allows an output at 16/20 bit light making the CL-70F a powerful tool for the range of compact handheld Light at a dynamic range of 1-to-1,000,000. professional imaging and entertainment markets. Measuring instruments between the The Evaluation Kit is prepared for specific colorimeter model CL-200A and the high customer calibrations. CRI measurement: precision spectrometer CL-500A. The CL-70F provides easy access to CRI The JENCOLOR® True Color sensors and measurement data. The display shows the signal ICs are an ideal solution for stabilization Ra value including all individual indices of LED light in regards of aging, binning and (R1 to R15) in a simple bar graph. MTCS-C3 Colorimeter temperature shifts. Additionally used in for LED Quality Control, industrial color measurement tasks, medial Easy measurement of correlated color Color Measurement applications and for metrology solutions. temperature (Tcp): The CL-70F can measure correlated color The new MTCS-C3 product family enables True Color measurement made simple temperature and the difference from the users to implement their own True Color The sensor system is based on the blackbody locus Δuv, values which are often Colorimeter into lighting, backlight, LED JENCOLOR® standard components used to describe the color of light sources. tests, color selection or other applications. MTCSiCF (True Color sensor) and MCDC04 The color temperature of light is defined as The MTCS-C3 is ideal to measure color (Signal converter). Therefore displays can be the absolute temperature (in Kelvin) at which coordinates (XYZ), CCT or brightness levels. measured at very low brightness levels and a blackbody would emit that particular color at high accuracy - even dimmable high of light. The colors of light emitted by a brightness power LEDs at high temperatures blackbody at various temperatures can be (>100°C) and brightness levels can be plotted on a curve which is called the measured close to the target. “blackbody locus”. Since the output of many light sources do not lie directly on The colorimeter has a micro USB interface the blackbody locus, “correlated color and can be directly controlled via Windows temperature” is used to describe software. The software includes ADC their colors. parameters such as gain, integration time, offset correction, and divider options. Easy Zero-adjustment without a receptor cap: The values can be individually calibrated to MAZeT’s OEM Sensor Board MTCS-C3 with Slide the ring on the diffusor counterclockwise USB interface for color measurements based the application and have several output to perform dark calibration. on CIE1931 can be used as stand-alone USB options (color spaces, export functions, etc.) color sensor The MTCS-C3 is an ideal solution for LED

tests in manufacturing or incoming goods lowest profile possible to most effectively inspection and is a cost-efficient solution prevent shadowing, coupled with space to be utilized at multiple measurement savings to address downsizing trends points. A simple user calibration can be in LED lighting designs. performed to the existing LED selection and as soon as color or brightness Delivering a 3.0 A rated current, deviations occur, actions can be taken. the 1.20 mm height TermiMate connector system provides an Even special features like flicker economical alternative to higher detection for displays are implemented. profile two-piece style LED housing For customer-applications, an adaptation components. A simple plug and of the software is offered or they can use receptacle terminal makes TermiMate the DLL libraries to develop and integrate connectors ideal for wire-to-board their own software solution. and coplanar board-to-board LED lighting configurations. The TermiMate The MTCS-C3 is available in 4 versions. system requires no direct wire soldering, As an OEM-Board with and without metal which reduces assembly cost and casing or as a Development Kit including eliminates risks associated with weak software with or without metal casing. solder joints that can cause problems Only one software license is required to in LED performance. use it for multiple sensors. Unlike soldered components, the TermiMate connector allows for easy mating and unmating. Designed with Molex TermiMate™ built-in floating tolerances, the TermiMate Connector Minimizes board-to-board connection supports LED Shadowing proper insertion to help prevent terminal damage during assembly and Molex Incorporated introduces the new maintenance. The wire-to-board TermiMate™ one-circuit terminal-style receptacle mates with the PCB crimp connector system. Designed to minimize facing to reduce risk of signal conductors the shadowing effect in LED lights and TV making contact with board circuitry. backlighting applications, the ultra-low A friction lock assures secure mating profile TermiMate coplanar board-to- and connectivity. board and wire-to-board connector reduces component and assembly costs “The brilliance of eliminating the for manufacturers. housing means Molex customers gain design flexibility, improve LED reliability, and save money with new TermiMate connectors when compared with a traditional two-piece connector housing,” adds Tanabe.

By combining best-in-class electrical, thermal and optical expertise with in-house design and manufacturing capabilities, Molex creates LED light modules and connectivity solutions Molex TermiMate™, the sleek new designed to overcome challenges connectors for LED lighting, help to save unique to LED lighting. space and money

“In LED applications, standard higher profile components are prone to create unwanted shadowing that negatively impacts the light quality,” said Goji Tanabe, regional product manager, Molex. TermiMate connectors provide the

Researchers Propose New Technology without Rare Earth Metals for LED Lighting At the 250th meeting of the American Chemical Society a novel approach to generate white light without using rare earth metals was presented. The researchers claim that this approach will lead to cheaper warm white LEDs than the currently used technologies. A press conference on this topic was held on August19, at 9 a.m. Eastern time in the Boston Convention & Exhibition Center.

An LED coated with a yellow “phosphor” is shown turned off (left) and then turned on (right). This “green” LED is inexpensive and provides warm white light (Credit: Zhichao Hu, Ph.D.)

Highly efficient, light-emitting diodes (LEDs) could slash the world’s electricity consumption. They are already sold in stores, but more widespread adoption of the technology has been hindered by high costs due to limited availability of raw materials and difficulties in achieving acceptable light quality. But researchers will report today that they have overcome these obstacles and have developed a less expensive, more sustainable white LED.

“If more people in the U.S. used LEDs in their homes and businesses, the country’s electricity consumption could be cut in half,” says Zhichao Hu, Ph.D., a member of the Rutgers University team that performed the research under the direction of Jing Li, Ph.D. At that time, he was a graduate student. He is now a postdoc at Rutgers and is studying the recovery of rare-earth elements there. Zhichao adds that studies show substituting one LED light for a common incandescent light bulb in every American household could save the nation $700 million annually in energy costs.

To achieve the common, soft white light that consumers expect, current LED technologies typically use a single semiconductor chip to produce light, usually blue, and then rely on a yellow-emitting “phosphor” coating to shift the color to white. That’s because LEDs do not emit a white light. The phosphor is made from materials, such as cerium-doped yttrium aluminum garnet, that are composed of rare-earth elements. These elements are expensive and in limited supply, since they are primarily available only from mining operations outside the U.S. Additionally, the light output of these phosphors tends to be harsh, “cold” colors.

Li’s team is developing hybrid phosphor-based technologies that are much more sustainable, efficient and low-cost. They combine common, earth-abundant metals with organic luminescent molecules to produce phosphors that emit a controllable white light from LEDs. By varying the metal and organic components, the researchers can systematically tune the color of the phosphors to regions of the visible light spectrum that are most acceptable to the human eye, Hu and Li note. The team is continuing to experiment and develop other rare-earth-free LED phosphors based on different metals and organic compounds.

Many material combinations are possible, so Experiments with some materials have Quantum Dot Technology they use a computational approach to initially shown that the team’s technology can cut may Help Light the Future sort through the possibilities and to predict LED costs by as much as 90 percent from what color of light the various metals and current methods that rely on rare-earth Advances at Oregon State University in organics combinations will emit. They then elements. They have several granted and manufacturing technology for quantum dots test the best combinations experimentally. pending U.S. patents and are exploring may soon lead to a new generation of LED manufacturing possibilities. lighting that produces a more user-friendly Their approach allows a systematic fine white light, while using less toxic materials tuning of band gaps and optical emissions Funding for this research was provided by and low-cost manufacturing processes that that cover the entire visible range, including the National Science Foundation and take advantage of simple microwave heating. yellow and white colors. As a result, Rutgers University. Hu is currently funded their LEDs can be fine-tuned to create a by the Department of Energy’s Critical warmer white light, similar to cheaper but Materials Institute. inefficient incandescent lights. Their approach shows significant promise for use in general The American Chemical Society is a lighting applications. nonprofit organization chartered by the U.S. Congress. With more than “One of the challenges we had to overcome 158,000 members, ACS is the world’s was to figure out the right conditions to largest scientific society and a global leader synthesize the compound,” Hu notes. “Like in providing access to chemistry-related cooking, the synthesis requires a ‘recipe’. It’s research through its multiple databases, The orange color in the letters “OSU” is often not the case that one can simply mix peer-reviewed journals and scientific produced from “quantum dots” viewed under the starting materials together and get the conferences. Its main offices are in a microscope, as they absorb blue light and desired product. We optimized the reaction Washington, D.C., and Columbus, Ohio. emit the light as orange - an illustration of conditions - temperature and the addition of some of the potential of new technology being developed at Oregon State University a solvent - and developed an easy procedure (Image courtesy of Oregon State University) to make the compound with high yield.”

The cost, environmental, and performance Quantum dots are nanoparticles that can be improvements could finally produce solid used to emit light, and by precisely controlling state lighting systems that consumers really the size of the particle, the color of the light like and help the lighting bill almost in half, can be controlled. They’ve been used for researchers say, compared to the cost of some time but can be expensive and lack incandescent and fluorescent lighting. optimal color control. The manufacturing techniques being developed at OSU, A key to the advances is the use of both a which should be able to scale up to large “continuous flow” chemical reactor, volumes for low-cost commercial applications, and microwave heating technology that’s will provide new ways to offer the precision Litecool have shown promising results for new conceptually similar to the ovens that are needed for better color control. LED package design that gives focused light part of almost every modern kitchen. beams with no secondary optics or reflectors Some past systems to create nanoparticles The continuous flow system is fast, for uses in optics, electronics or even Nearly all LED packages come with a near cheap, energy efficient and will cut biomedicine have been slow, expensive, Lambertian emission leaving the luminaire manufacturing costs. And the microwave sometimes toxic and often wasteful. manufacturers to work out how to shift that heating technology will address a problem into something useful for their application. that so far has held back wider use of these Other applications of these systems are also This gives both an efficiency and financial systems, which is precise control of heat possible. Cell phones and portable electronic cost which Litecool believes they can needed during the process. The microwave devices might use less power. Compounds eliminate with their packages. approach will translate into development with specific infrared or visible light emissions, of nanoparticles that are exactly the could be used for precise and instant Litecool designs and develops LED COBs right size, shape and composition. identification of e.g. counterfeit bills or products. and packages from scratch. That means they can change the optical surfaces within the “There are a variety of products and OSU is already working with the private sector package allowing for different emission technologies that quantum dots can be to help develop some uses of this technology, patterns. A recent project completed by applied to, but for mass consumer use, and more may evolve. The research has been Litecool has shown that with minor changes possibly the most important is improved supported by Oregon BEST and the National to these surfaces they have been able to LED lighting,” said Greg Herman, Science Foundation Center for Sustainable produce a 36-degree spot with efficiency an associate professor and chemical Materials Chemistry. above 90%. The project is set to continue engineer in the OSU College of Engineering. and will look to bring the beam angles down to levels suitable for the majority of lighting “We may finally be able to produce low cost, applications including spotlights. It is energy efficient LED lighting with the soft Litecool Demonstrates expected that Litecool will incorporate this quality of white light that people really want,” that Narrow Beam LED technology within the Lumen Block product Herman said. “At the same time, this Packages are Possible range due out next year. technology will use nontoxic materials and dramatically reduce the waste of the Litecool has been working on various “This is the first iteration and it looks materials that are used, which translates to LED package designs to give luminaire promising. We will be able to reduce beam lower cost and environmental protection.” manufacturers an LED package that doesn’t angles down to around 20 degrees with need any further lensing or reflectors to give about 90% efficiency. It doesn’t cost much Some of the best existing LED lighting now the desired beam patterns for lighting to make a few design tweak in our packages being produced at industrial levels, Herman applications. Litecool is well known for their so it looks like we are going to be able to said, uses cadmium, which is highly toxic. innovative approaches to thermal offer specific beam patterns directly from our The system currently being tested and management but this is their first real LED packages with greater efficiency and developed at OSU is based on copper- development in optical technology and it lower system costs than what can be indium-diselenide, a much more benign looks like it could be pretty useful for achieved at the moment,” says James material with high energy conversion efficiency. lighting manufacturers. Reeves, CEO of Litecool.

WEBINARS

CoolMOS™ CE and LED Driver ICs - The Ideal Combination from LED Tubes to LED Drivers Learn more about CoolMOS™ CE, the proven benefits of superjunction technology, and the powerful combination of CoolMOS™ CE and the suitable LED Driver ICs. Join our webinar on Sept 29, 2015! www.led-professional.com/Infineon-Webinar

NEWS PRODUCT LAUNCHES AT LPS 2015 30

Non-Glare Hybrid Optics with Defined Beam Angles by Auer Lighting

Auer Lighting presents new hybrid glass Pressed-in SNAP IT® features enable an easy optics. The Jupiter product line is designed for mounting as well as a user-friendly exchange to advanced LED luminaires featuring the lighting other beam angles in the luminaire. designer’s desire: no glare and defined beam The optic is made from durable SUPRAX® glass angles. that easily withstands temperatures up to 450 °C. The Jupiter is a combination of a lens and a It lasts even under harsh conditions. No yellowing reflector, merging two optical concepts in only effect is seen, nor any degradation over time. one product. The lens in the center greatly The surface of the glass and even the coating reduces the amount of direct emission from the is easy to clean, scratch-resistant and guarantees LED that typically leads to unwanted light spill. longest life times. The reflector directs the light via its facetted The Jupiter optic is now available as 50 mm free-form surface into a defined angular cone diameter version with narrow, medium and flood forming nicely shaped Lambertian distributions. beam angles, best for LEDs with 6 mm LES or The durable dichroic coating, using Auer’s below. The same beam angles are available for the patented PICVD technology, results in a slightly larger 70 mm version, which is optimized reflectivity >95%. for LEDs with a LES of 9 mm and below.

Dow Corning® EI-1184 Clear Encapsulant

Material description Key features of this advanced material Dow Corning® EI-1184 Encapsulant is a include: clear, two-part silicone product designed to • Protects against harsh outdoor offer reliable Electronics protection for lamps environment and luminaire components in interior and • UL 94-V1, UL 746C (f1) outdoor applications. • High transparency and less yellowing Featuring high transparency and • Two-part, 1:1 mix ratio weatherability, the two-part silicone • Rapid and versatile cure processing encapsulant delivers reliable, long-lasting controlled by temperature protection of sensitive LED electronics in environments containing moisture, ultraviolet (UV) Dow Corning® EI-1184 Clear Encapsulant light, thermal cycling and extreme is suitable for: temperatures for both indoor and outdoor lamp and luminaire applications. • Encapsulating rigid and flexible circuit boards indoor and outdoor LED Lighting applications

GL TEC Control System

Today, the realm of light measurement is To this end, GL Optic has taken the step to expanding beyond classic optical measurement develop and now offer a complete solution to meet and investigating phenomena like thermal the new thermal control demands. The GL TEC conditions, current or power levels. Requirements Control System includes our top-of-the-line Spectis placed on luminaire developers and manufacturers 6.0 laboratory grade spectrometer, coupled with a either by updated standards or the market directly state-of-the-art TEC controller and mount, along go beyond the classic sphere-based system and with a programmable power supply and the GL OPTI for example, call for stable and reliable ambient SPHERE 500. With detailed control from the temperature conditions. The need has therefore temperature controller, the module can create the arisen to stabilize the temperature of LED fixtures optimal stable conditions for measurements, during measurements or simulate different LED or simulate nearly any temperature conditions. performance temperatures. In fact, the latest test The hardware is integrated with GL AUTOMATION, method standards, like CIE S 025/E:2015, a powerful module of the GL SPECTROSOFT software are demanding that lighting developers and solution, which essentially lets you control the entire manufacturers look at the issues of thermal set of peripheral devices and plan, launch and control more closely. monitor any required automated testing scenario.

Softswitcher SSW60Q from SwitchTech AB

The all new LED driver SSW60Q • Driver design for less weight and smaller size (V-36060SSWQ) is available in drive • Highe efficiency (up to 90%) over the entire powers of up to 60 W on two independent output range means increased energy savings output channels. At the same time all • Power factor up to 0,98 60 W can be utilized on a single channel or • Synchronized and dynamic adjustment of any other combination. It is suitable for switching patterns to reducte EMI large indoor installations such as office, • Impressive life time of 100 khs retail, hotel or conference rooms and • Intelligent software using microcontrollers special applications. It is also ideally suited means limitless control options including for demanding lighting needs in all 0/1-10 V, DALI, DMX, phase-cut control, locations. Its drive capabilities, extreme Wifi, Zigbee, Bluetooth etc.. flexibility and small size makes it a perfect • Scalable technology with customizable driver solution. features means short time to market The new digital design implies several • Custom drivers in low volumes due to advantage for digital LED drivers due to reprogramming using software tool characteristics of the Softswitcher platform:

PLEXIGLAS® WH Simplifies Manufacture of Slim Edge-Lit Panel Lights

A new product from Evonik Performance required size by typical processing methods Materials, PLEXIGLAS® WH, not only suitable for PLEXIGLAS® (e.g. CNC mill, simplifies manufacturing of slim edge-lit circular saw, laser). Costly optical simulations panel lights, but also enables new design for optimization of the light extraction options. patterns, as well as screen printing or laser PLEXIGLAS® WH combines several etching of the extraction pattern are no centerpieces of an edge-lit light guide panel longer necessary for edge-lit luminaire in a single product: a PLEXIGLAS® PMMA manufacturing with this product. light guide sheet, a light extraction pattern In addition to standard flat light guide optimized for homogeneity and efficiency, applications much more complex shapes are and a high performance light reflector layer. possible with this product by thermo- or Small volumes for validation are available vacuum forming processes, literally opening immediately upon request. The length of the up a new dimension of design options for panel is variable and can be trimmed to its edge-lit LED luminaires.

Energy Harvesting Ambient Sensor for Tunable White Control

Light quality is a very important factor in human of DALI installation where the range of Bluetooth wellbeing. In addition to lighting intensity, Smart is sufficient (up to 50 m without obstacles). Correlated Colour Temperature (CCT) also has a Furthermore, BlueBridge is fully compatible with fundamental influence on our mood and the EHA Sensor. Using the app, users can performance. Furthermore, we live in an era of configure a simple regulation loop that reads data smart of environmentally responsible technologies. from an EHA Sensor and control Tunable White To facilitate control, iLumTech has developed luminaires (defined by group addresses) using BlueBridge, and interface between Bluetooth BlueBridge as an interface with the DALI bus. Smart and standard DALI buses. BlueBridge is The EHA Sensor is a pocket-sized solution for powered from directly from the DALI bus and so accurate and realistic measurement of ambient does not need any power source. Using lighting intensity and CCT values at task areas in BlueBridge allows for complete control via a DALI offices and homes. In combination with BlueBridge installation, even of type 8 devices (colour control). and compatibility with Bluetooth Smart, it allows The GUI is an app that runs on Android devices for comfortable date presentation and wireless that support Bluetooth Smart. The control features control of DALI installations (exclusive of the wiring of BlueBridge can be used generally for any type of the luminaires).

Dow Corning® CI-2001 White Reflective Coating

Material description: Key features of this advanced material The Jupiter optic is now available as 50 mm include: diameter version with narrow, medium and flood • 96% reflectance at 5-mil coating thickness and beam angles, best for LEDs with 6 mm LES or 94% reflectance at 3-mil coating thickness below. The same beam angles are available for the • One-component formulation offers simple slightly larger 70 mm version, which is optimized room-temperature cure that can be for LEDs with a LES of 9 mm and below. accelerated with heat for higher productivity • Applies easily by spraying, dipping, brushing Uses: or flowing Dow Corning® CI-2001 White Reflective • After cure, forms a tough, resilient coating Coating is used as a bright-white reflective with a nontacky surface coating to enhance light output and efficiency for • Reliable, long-lasting performance between light reflectors, mixing chambers, backlightunits, -45 and 200°C (-49 and 392°F) light engine units, printed circuit boards and • Less than 50 g/l of nonexempt VOC content aluminum surfaces used in assembly of LED • UL flammability rating UL-V0 lamps and luminaires.

Gaggione LLC66N7 - Silicone Narrow Beam Collimator

Gaggione expanded its LEDnLIGHT® The use of optical silicone delivers reliable family to address the latest performance mechanical and optical performance demands for solid-state lighting with the despite exposure to high lumen densities, patented new collimator LLC66N7 in outdoor ultraviolet (UV) light or external optical grade silicone with a narrow beam temperatures cycling between -40°C and angle down to 6° based upon LES. 150°C and minimizes the injection channel The unique design of Gaggione’s to less than 2 mm. LLC66N7 with an internal concave cylinder Features: shape, a negative counter draft angle, permits the use of larger, brighter COB light Dimensions: d = 67.2 mm, h = 36.0 mm sources with optimal light output ratios up Material: MS-1002 moldable Silicone to 23 mm LES. Our patent pending designe Material Dow Corning 80 erases stray light detracting from the output Shore, UL listed of LED light sources. Gaggione‘s proprietary Tolerances: Comply with NFT47001 output micro texture contributes to an category M1 incomparable homogeneous light distribution.

ISD-100-HFT - A New Integrating Sphere from Gigahertz-Optik

LED lamps are highly effective. Even so, possible to measure various light parameters when they are in use the electronic control like light flux, spectrum and color. The sphere gear produces heat. For LEDs as a can be opened and makes it possible to semiconductor, this causes changes in the install lamps with various sockets with its luminous flux, spectrum and color and can adjustable sample holder. The optional four result in a reduction of the life span. Therefore pole measuring sockets allow precise the heat must be dissipated effectively. The measurements of the electric operation orientation of the lamp, with the socket facing parameters of the lamp. The integrating downwards, upwards or horizontal, can have sphere is easy to turn and lock on its an effect on the thermal management. horizontal axis. This makes it easy to qualify Therefore it is important to take the intended lamps in various operation positions. operating position into account when The BiTec-Light sensor Spectroradiometers evaluating the lighting technology. from Gigahertz-Optik GmbH are ideal for use The new Integrating Sphere ISD-100-HFT with the sphere. Their construction concept from Gigahertz-Optik GmbH has a avoids the use of light conductors and their circumference of one meter and makes it disadvantages.

EVENT NEWS OUT OF BOUNDS DESIGN CONTEST 34

OUT OF BOUNDS DESIGN CONTEST STUDENTS EXPLORING COMPLETE FREEDOM IN LIGHTING DESIGN

Seventeen innovative prototypes are Science in Munich, the internationally the lamp stays flat in the design without any the outcome of a four-month long well-known industrial designer Ingo Maurer, electronic ballast. This makes it easier to journey taken by students from the Andreas Weisl from Seoul Semiconductor, carry the lamp and change locations. Department of Design at the Stefan Eckstein - President of the University of Applied Sciences in federation of German lighting designers, Ms. Gillitzer has a passion for light and Munich, Germany. In collaboration Markus Helle - Chief Editor at the Highlight technology and she has taken part in with Seoul Semiconductors they Magazine and Siegfried Luger - Founder of other lighting projects before. “Seoul got to experiment with AC-LED LED professional. According to the jury it Semiconductor’s technology is something modules as light sources and discover was extremely difficult to choose a winner, very functional, in my opinion. So it was lighting design without the traditional as all prototypes were so different in their clear to me from the beginning that I would barriers of LEDs. The prototypes will designs and application. Finally they design something useful and functional be exhibited at the LED professional agreed not to award any of the projects but where the technology makes sense”, Symposium +Expo 2015 in Bregenz, to highlight three prototypes, which were explained Ms. Gillitzer. In the research Austria. most interesting from a technical point phase of her project she realized that most of view: A construction lamp from Lena of the existing construction lights are very Who better to explore complete freedom in Gillitzer, a hanging lamp from Julian Lang functional in their aesthetics and shape and lighting design than those with fresh eyes and another hanging lamp from therefore often not attractive. She decided and minds, namely design students? Christopher Gros. “I am very proud of the to design something different: a functional This idea laid the foundation for Out of fantastic results. The seventeen luminairies lamp which is highly aesthetic at the same Bounds Design Contest, which awarded the couldn’t have been more diverse. time. The most difficult part was for her to most imaginative, forward-thinking designs. This diversity highlights the quality and deal with high power LEDs, which produce “By engaging with young and creative creativity of the young designers.”, a lot of heat and therefore need a certain students, who have no limits and could stated Prof. Naumann, who guided the sized cooling body and distance to the work unreservedly with this technology, group of students through the project. diffusor. “So in the end, the light effect had we wanted to provide a platform to The award ceremony will take place on to take a back seat”, said Ms. Gillitzer. demonstrate what great solutions can be Sept. 22nd at the LpS 2015 as a part of She focused on the body of the lamp, which realized with the design freedom enabled the “Design meets Technology” program. is the cooling body at the same time. by Acrich. By doing so, it was our goal to All seventeen prototypes will be exhibited show established lighting manufacturers during the three-day LpS event in Bregenz, In a next step she plans to give the 3D-Data what excellent designs can be achieved the meeting point for the international of her construction lamp called “Trinity” to a with new technologies like AC-LED lighting industry. professional miller. According to her it will technology, and that in reality the barriers be possible to optimize the cooling body in are not as high as the perception today”, A student describes her journey order to have an even better cooling effect said Andreas Weisl, Vice President Europe, Magdalena Gillitzer created an innovative through thinner cooling ribs. She also plans Seoul Semiconductor. construction lamp, consisting of two to optimize the light effects. After asking her foldable light panels. The panels can be about her future plans she said “It would be Award Ceremony at the LpS 2015 turned and twisted for creating different great to use the Acriche 3 Technology one On July 9th the prototypes were presented light directions and different impressions. day to have a dimmable light”. to a jury comprising of Prof. Peter She described the Acrich3 technology as Naumann from the University of Applied very useful and important for her lamp as LpS Event Website: www.LpS2015.com

The IAU as a partner of IYL is working towards raising awareness of light pollution and providing solutions. For the IAU’s Cosmic Light Working Group, the IYL is a big chance - via the “Cosmic Light” Cornerstone - to build on the success of the “International Year of Astronomy” - 2009. Furthermore, the IYL is providing the IAU with another welcome opportunity to reach out to other communities and particularly to LED manufacturers and users.

IYL 2015 - AN ASTRONOMY’S PERCEPTION OF THE WISE USE OF LEDS TO MINIMIZE LIGHT POLLUTION by Malcolm Smith, IAU

Several articles in January’s LpR (Issue 47) this waste. Of course, communities have per capita than comparably sized cities already show an understanding that it is to decide what to do about the in the US - and the gap increases with important that the various professional downward-directed light that is necessary, increasing city size. communities involved in lighting our planet in moderation, yet will be reflected upwards continue to improve communication with and will affect astronomers and others Until recently, astronomers have been able to each other. It is via the IYL that some wishing to see the natural night sky. In recent observe blue light from the cosmos without astronomers are getting to know more about decades, the response of astronomers has much interference from the artificial light from “Trends and Technologies for Future Lighting been to move away from population centers, humans, thanks mainly to the widespread Solutions” - which is why this contact with locating their observatories far from cities use of (yellow) sodium lamps. With the the LpR is especially welcome. The IAU and encouraging local economies to benefit introduction of LED lights, the amount of blue Focus Meeting on Light Pollution in August from astronomy-friendly activities such as light increases. The increasing interference also included a session on “Advances in astro-tourism. However, the planet is now from this blue LED light is particularly LED technology and options for running out of such places. unwelcome to astronomers. Since about 2012, spectral management”. therefore, astronomers at several of the Currently more than half the human major optical observatories have begun Light pollution is useless artificial light. population lives in cities. The entire world working directly with LED manufacturers to Huge amounts of such stray light are still is now imaged each night at 750-meter help in the development of astronomy- needlessly being sent upwards - all night. resolution by the Visible Infrared Imaging friendly lighting systems, which shine their Substantial amounts of this wasted light are Radiometer Suite Day-Night Band on board light below the horizontal and keep the then scattered and/or refracted back to the Suomi weather satellite. It is now amount of blue light in their output spectrum earth. This creates a luminous glow in becoming clear that the way that cities use below about 15% of the light energy in the the sky that competes with the faint light light varies between regions and countries. rest of the optical spectrum between 420 nm being studied by optical astronomers. For example, according to recent remote and 690 nm. Demand for such limited- Appropriately designed LED fixtures currently sensing research (by Chris Kyba et al.) spectrum lighting has appeared in the being installed in many cities can help avoid German cities emit several times less light Canary Islands, Hawaii and Chile, where the astronomy industry now has significant economic impact. The first Amber LEDs with an emission between 540 nm and 630 nm were installed in La Palma in 2012.

In the “International Year of Astronomy”, 2009, IAU has had special success in the area of outreach and education, with thousands of schools around the world showing interest and ingenuity in responding to the educational needs of humanity, which had almost unconsciously been shutting itself inside a ball of light on a tiny planet. Humanity has the right to continue to learn from what the sky can tell us. It also has the skill to develop competitive, astronomy-friendly, LED lighting - as well as showing increasing interest in this option. IAU aims to continue this successful work in the IYL 2015. M.S.

LpS EVENT OVERVIEW DAY 1 Opening 10.00 - 10.30 Opening & Scientific Award Ceremony | Grosser Saal SEPT. 22ND TUESDAY 10.30 - 12.00 Keynotes | Grosser Saal

Parallel Sessions

13.30 - 18.00 Light Quality | Seestudio 2015

13.30 - 15.30 Connectivity & Security | Seefoyer

16.30 - 18.00 Reliability & Lifetime | Seefoyer

13.30 - 15.30 Standardization | Propter Homines

16.30 - 18.00 Workshop Light Measurement by GL Optics | Propter Homines

10.00 - 20.00 Design meets Technology Day | Grosser Saal, Foyer & Expo

Evening Events

18.00 - 20.00 Poster Session | Foyer

- 18.00 - 20.00 Exhibition Reception & Oktoberfest | Werktstattbühne & Seitenbühnen

PROGRAM DAY 2 Parallel Sessions

RD SEPT. 23 08.30 - 15.30 Light Sources | Seestudio WEDNESDAY 08.30 - 15.30 Smart Controls & Drivers | Seefoyer

08.30 - 12.30 Thermal Management | Propter Homines

13.30 - 15.30 Optics | Propter Homines

16.30 - 18.00 Workshop OLEDs by LG Chem | Saal Bodensee

16.30 - 18.00 Workshop Optics by Lambda Research | Saal Bodensee

16.30 - 18.00 Workshop Thermal Management by ams | Saal Bodensee

Evening Events

17.00 - 18.00 Press Conference | Parkstudio

18.30 - 23.00 Get-Together Event | Boat Trip on Lake Constance

DAY 3 Parallel Sessions

SEPT. 24TH 09.00 - 10.30 Lighting Systems | Seestudio THURSDAY 09.00 - 10.30 Optics | Propter Homines

09.00 - 12.30 Measurement and Production | Seefoyer

11.30 - 12.30 Workshop Smart Controls by Luger Research | Propter Homines

11.30 - 12.30 Workshop Light Mixing by LightCube/Uni Padua | Seestudio

09.00 - 12.30 Workshop Automotive Lighting by EPIC | Saal Bodensee

Plenum Sessions

13.30 - 14.30 Tech-Panel: Key Trends & Technologies | Seestudio

14.30 Closing | Seestudio

www.lps2015.com DAY 1 - SEPTEMBER 22ND - TUESDAY

Opening, Keynotes & Connectivity, Security, Standardization & Design meets Time Light Quality Reliability & Lifetime Light Measurement Technology Day

10.00 Grosser Saal DMT Day | Grosser Saal Opening & Opening Scientific Award Ceremony

10.30 KEYNOTE | Grosser Saal DMT Day | Grosser Saal Semantic Light Keynote Prof. Zary Segall, Royal Institute of Technology, Sweden

11.00 KEYNOTE | Grosser Saal DMT Day | Grosser Saal The Second Wave of Lighting Inno- Keynote vation - Towards Lighting Beyond Illumination Rogier van der Heide, Chief Design & Marketing Officier at Zumtobel Group, Austria

11.30 KEYNOTE | Grosser Saal DMT Day | Grosser Saal Trends and Challenges for System Keynote Integration Dr. Jy Bhardwaj, CTO at Lumileds, USA

BREAK

13.30 LIGHT QUALITY | Seestudio CONNECTIVITY & SECURITY | Seefoyer STANDARDIZATION | Propter Homines DMT Day | Foyer, Expo Human Centric Lighting - What We Why We Need Smarter Smart Lighting OpenAIS - Innovation Towards an Open Exhibition Know and What is Needed Dr. Walter Werner, CEO at Werner Mgt. Consulting, Architecture for Intelligent Solid-State Walkthrough DI Peter Dehoff, Zumtobel Group & LightingEurope, Austria Lighting Austria, The Netherlands Dr. Christian Moormann, Head of Global Technolo- gy, Tridonic, Austria

14.00 LIGHT QUALITY | Seestudio CONNECTIVITY & SECURITY | Seefoyer STANDARDIZATION | Propter Homines DMT Day | Foyer, Expo CIE Test Method for LED Lamps, LED Lighting Systems and Cyber Security Zhaga Standardization of LED Light Exhibition Luminaires and LED Modules Ken Modeste, Principal Engineer at Underwriter Engines, Modules and Drivers Helps to Walkthrough Dr. Peter Blattner, Head of Optics Laboratory at Laboratories (UL), USA Simplify LED Luminaire Design METAS, Switzerland Musa Unmehopa, Secretary General at Zhaga Consortium, The Netherlands

14.30 LIGHT QUALITY | Seestudio CONNECTIVITY & SECURITY | Seefoyer STANDARDIZATION | Propter Homines DMT Day | Foyer, Expo Concepts of Intelligent Lighting and Intelligent Methods to Secure An Introduction to DALI 2 Exhibition LED Luminaires Taking Color Quali- Connected Lighting and Smart City Steve Roberts, CTO at Recom, Austria Walkthrough ty and Human Centric Lighting into Installations Account Dr. Geoff Archenhold, Serenity Lighting, UK Prof. Tran Quoc Khanh, TU Darmstadt, Germany

15.00 LIGHT QUALITY | Seestudio STANDARDIZATION | Propter Homines DMT Day | Expo The Degrees of Freedom Provided by Challenges and Solutions of Photobio- Luminary Design Prize Modern Methods to Tune CCT and LED logical Safety Assessment for Lighting Wavelengths Products Wojtek Cieplik, LEDengin Prof. Jiangen Pan, CEO at Everfine, China

BREAK

16.30 LIGHT QUALITY | Seestudio RELIABILITY & LIFETIME | Seefoyer Propter Homines DMT Day | Expo Quality of LED Lamps for Residential Reliability of High Power LEDs: From WORKSHOP Exhibition in European Market and Associated Gradual to Catastrophic Failure LIGHT MEASUREMENT Health Issues Prof. Matteo Meneghini, University of Padua, Italy by GL Optic, Germany Prof. Georges Zissis, Toulouse 3 University, France

17.00 LIGHT QUALITY | Seestudio RELIABILITY & LIFETIME | Seefoyer Propter Homines DMT Day | Expo SSL Solutions for Human Centric LED Tunnel Lamp - A Reality Check: WORKSHOP Exhibition Lighting 50,000 Hours Field Data and Lifetime LIGHT MEASUREMENT Dr. Nicola Trivellin, LightCube, Italy Alexander Wilm, SSL Expert, OSRAM Opto by GL Optic, Germany Semiconductors, Germany

17.30 LIGHT QUALITY | Seestudio RELIABILITY & LIFETIME | Seefoyer Propter Homines DMT Day | Expo Sky Luminance and Radiance Distribu- Statistical Analysis and Prediction of WORKSHOP Exhibition tion Patterns: Empirical Assessment LED Lifetimes LIGHT MEASUREMENT and Computational Models Dr. Wolfgang Scheuerpflug, Diehl Aerospace, by GL Optic, Germany Prof. Ardeshir Mahdavi, Technical University Vienna, Germany Austria

18.00 Werkstattbühne & Seitenbühnen Foyer Werkstattbühne & Seitenbühnen DMT Day | Expo | OKTOBERFEST POSTER SESSION EXHIBITION RECEPTION Networking 20.00

www.lps2015.com DAY 2 - SEPTEMBER 23RD - WEDNESDAY

Time LED & OLED Light Sources Smart Controls, Drivers & Optics Thermal Management & Optics

08.30 LIGHT SOURCES | Seestudio SMART CONTROLS & DRIVERS | Seefoyer THERMAL MANAGEMENT | Propter Homines Solid-State Light Products Design Breakthrough Energy and Light Quality Results of EnLight The Effect of Dynamic Thermal Management for Mauro Ceresa, Field Application Engineer, Cree, Italy Lighting Solutions Applied to a Hospitality Smart Controlled Solid State Lighting Systems Environment Dr. Mehmet Arik, Ozyegin University, Turkey Dr. Herbert Weiß, Project Manager Corp. Technology at OSRAM, Germany

09.00 LIGHT SOURCES | Seestudio SMART CONTROLS & DRIVERS | Seefoyer THERMAL MANAGEMENT | Propter Homines Progress in Single Crystal Luminophores for Human-Focused Outdoor Illumination: A Trade- A Case Study: Opto-Thermal Modelling of a High Power LEDs and LDs off Between Pleasing Color and Circadian Action Mid-Power LED Dr. Jan Kubat, Head of Materials and Precision Optics at Dr. Prancisskus Vitta, Vilnius University, Lituanica Dr. V.D. Hildenbrand, Researcher at Philips Lighting Solutions, Crytur, Czech Republic The Netherlands

09.30 LIGHT SOURCES | Seestudio SMART CONTROLS & DRIVERS | Seefoyer THERMAL MANAGEMENT | Propter Homines An Iterative Optical and Thermal Simulation A New Software Approach/Architecture for Reliability of Interconnects in LED Lighting Method for Proper Simulations of Phosphor Scalable Distributed Lighting Control Assemblies Utilizing Metal Clad Printed Circuit Converted LEDs Prof. Peter Niebert, CTO LED‘s CHAT, France Boards Dr. Wolfgang Nemitz, Researcher at Joanneum Research, Justin Kolbe, Principal Engineer at The Bergquist Company, Austria USA

BREAK

11.00 LIGHT SOURCES | Seestudio SMART CONTROLS & DRIVERS | Seefoyer THERMAL MANAGEMENT | Propter Homines LED Lighting for Visual Merchandising Wireless Mesh Networks Demystification Thermal Impedance Analysis of LED Modules Dr. Daniel Doxsee, Deputy Managing Director of Nichia Vladimir Sulc, CEO at MICRORISC, Czech Republic Dr. Stefan Defregger, Program-Manager at Material Center Europe, Germany Leoben, Austria

11.30 LIGHT SOURCES | Seestudio SMART CONTROLS & DRIVERS | Seefoyer THERMAL MANAGEMENT | Propter Homines Trends in SMD LED Packages for General Quality Characteristics of LED Power Supplies Nanoceramic Substrates for Thermal Manage- Lighting and Drivers ment of High Brightness LEDs Dr. Christopher Keusch, Everlight Electronics, Germany DI Stephan Wegstein, CEO at sysLED, Germany Dr. Giles Humpston, FAE at Cambridge Nanotherm, UK

12.00 LIGHT SOURCES | Seestudio SMART CONTROLS & DRIVERS | Seefoyer THERMAL MANAGEMENT | Propter Homines Leveraging Chip Scale Package Technology to Reliable and Cost Effective LED Drivers Impro- Advantages of Using Thermally Conductive Deliver a Robust and Future-Proof Platform ving Perception Artefacts and Grid Compatibility Polymers for Heat Sinks Ingolf Sischka, Technical Solution Manager at Lumileds, Prof. Eberhard Waffenschmidt, Cologne University, Germany Dr. Klaus S. Reinartz, Marketing Manager at Bayer Material Germany Science, Germany

BREAK

13.30 LIGHT SOURCES | Seestudio SMART CONTROLS & DRIVERS | Seefoyer OPTICS | Propter Homines Luminescent Glasses and Glass Ceramics for Advantages and Challenges of Modern Software Why Moldable Silicone is Driving Innovation in En- White Light Emitting Diodes Based Digital SMPS LED Drivers gineering of LED Optics for Professional Lighting? DI Franziska Steudel, Research at Fraunhofer, Germany Mikael Pettersson, R&D Manager at SwitchTech, Sweden Dr. Francois De Buyl, Dow Corning, Belgium

14.00 LIGHT SOURCES | Seestudio SMART CONTROLS & DRIVERS | Seefoyer OPTICS | Propter Homines Spectrally Tuneable SSL Solutions and Appli- How to Combine Smart Lighting with a Driver- Sensitivity of the Optical Performance of LED Illu- cations less, AC-Driven Solution mination Systems to Manufacturing Tolerances Dr. Josep Carreras, Head of the Lighting Group at IREC, Spain Lorenz Bauer, Field Application Engineer at Seoul Semicon- Dr. Christian Paßlick, Engineer at Auer Lighting, Germany ductor, Germany

14.30 LIGHT SOURCES | Seestudio SMART CONTROLS & DRIVERS | Seefoyer OPTICS | Propter Homines Human Centric Lighting: The Future of the PFC Flyback with Software Controlled Digital Styrenics for LED lighting - How Specialty Styre- Lighting Industry Driver nics Open New Possibilities in LED Lighting Prof. Guenther Leising, Lumitech, Austria Ulrich vom Bauer, Infineon, Germany Dr. Eike Jahnke, Technical Product Manager at Styrolution, Germany

15.00 LIGHT SOURCES | Seestudio OPTICS | Propter Homines What is the Future of OLED for Lighting? Thin-Film Light Management System for Intelli- Pars Mukish, Analyst at Yole Developpement, France gent Large-Area LED Luminaires Dr. Oscar Fernandez, CSEM, Switzerland

BREAK

16.30 Saal Bodensee Saal Bodensee Saal Bodensee | WORKSHOP WORKSHOP WORKSHOP 18.00 OLEDs OPTICS THERMAL MANAGEMENT by LG Chem, Korea by Lambda Research, USA by ams, Germany

17.30 Parkstudio PRESS-CONFERENCE

18.30 Boat trip on Lake Constance | GET TOGETHER EVENING 23.00

www.lps2015.com DAY 3 - SEPTEMBER 24TH - THURSDAY

Lighting Systems, Light Measurement & Optics & Smart Controls Automotive Lighting Time Mixing & Tech-Panel Production

09.00 LIGHTING SYSTEMS | Seestudio MEASUREMENT & PRODUCTION | OPTICS | Propter Homines Saal Bodensee The Paradigm Shift of Residential Seefoyer Better Light Through Optical Design WORKSHOP Lighting from Retrofit Lamps to Fully New Standards for the Photometry of for Manufacturing AUTOMOTIVE LIGHTING Integrated Fixtures LED Based Light Sources - A Challen- Dr. Angelika Hofmann, Optical Design Manager at by EPIC Jeremy Ludyjan, Director of Innovation at Bulbrite ge for the Laboratories kdg Opticomp, Austria Industries, USA Dr. Udo Krüger, Head of Photometry, TechnoTeam, Germany

09.30 LIGHTING SYSTEMS | Seestudio MEASUREMENT & PRODUCTION | OPTICS | Propter Homines Saal Bodensee Six-Channel LED-Luminaire for Retail Seefoyer Diffusion Panels - The Way Out of the WORKSHOP Lighting Impact of New SSL Standards on Go- Glaring Inhomogeneous LED Misery AUTOMOTIVE LIGHTING Prof. Meike Barfuss, FH Suedwestfalen, Germany niospectroradiometric Measurements Dr. Dieker Henning, R&D Designer at VS Lighting, by EPIC Dr. Denan Konjhodzic, Application Engineer at Germany Instrument Systems, Germany

10.00 LIGHTING SYSTEMS | Seestudio MEASUREMENT & PRODUCTION | OPTICS | Propter Homines Saal Bodensee High-Temperature Reliability of Retro- Seefoyer 24/7 Custom Optics: Improved Capa- WORKSHOP fit LED Bulbs Effect of Thermal Management for bilities Increase Manufacturing Speed AUTOMOTIVE LIGHTING Dr. Matteo Dal Lago, LED Based Street Lighting Systems and Flexibility Significantly by EPIC Researcher at LightCube, Italy Gokhan Hasan, Engineer at Bosch & Siemens Bram Mueleblok, LUXeXceL, The Netherlands Home Appliance Group, Turkey

BREAK

11.30 Seestudio MEASUREMENT & PRODUCTION | Propter Homines Saal Bodensee WORKSHOP Seefoyer WORKSHOP WORKSHOP LIGHT MIXING Adhesive Developments for Low Cost SMART CONTROLS AUTOMOTIVE LIGHTING by LightCube & University of Padua, Italy Flip-Chip and High Precision Bonding by Luger Research, Austria by EPIC in LED Lighting Applications Andreas Kraft, Business Development Manager at DELO, Germany

12.00 Seestudio MEASUREMENT & PRODUCTION | Propter Homines Saal Bodensee WORKSHOP Seefoyer WORKSHOP WORKSHOP LIGHT MIXING New High Speed Assembly SMART CONTROLS AUTOMOTIVE LIGHTING by LightCube & University of Padua, Italy Technology by Luger Research, Austria by EPIC “Reel to Reel Flip Chip LED“ Franz Brandl, Head of R&D at Mühlbauer, Germany

BREAK

13.30 Seestudio | TECH PANEL 14.30 KEY TRENDS & TECHNOLOGIES

14.30 CLOSING

www.lps2015.com TECH-TALKSCATEGORY BREGENZ ANDREAS WEISL 42 Tech-Talks BREGENZ - Andreas Weisl, SSC Europe, Vice-President

Andreas Weisl Andreas Weisl is Vice-President of Seoul Semiconductor Europe GmbH, which he joined in November 2010. Prior to joining Seoul Semiconductor he spent 5 years with OSRAM Opto Semiconductors GmbH in various roles in Account and Distribution Management. Andreas studied Industrial Engineering and Information Technology at Munich University of Applied Sciences and joined a European Business & Management Program at the Brunel University of London. His thesis was titled “Development and Realization of sales and marketing concept for the new wireless technology ZigBeeTM”.

Seoul Semiconductor has more than 20 years of experience in semiconductor manufacturing and invests more than 10% of its annual revenue in LED research and development. On average, Seoul Semiconductor applies for more than 600 patents every year. Currently, the company holds more than 10,000 LED patents, including patents in core LED technologies such as Acrich, Acrich MJT, nPola, TV Direct Backlight Technology, UV, and many more. Seoul Semiconductor’s extensive patent portfolio in LED technology includes epitaxial growth, fabrication, packaging, and system application of LED technology. LED professional talked with Andreas Weisl, Vice-President of Seoul Semiconductor Europe GmbH about their business, technologies and solutions.

LED professional: Thank you very much for LED professional: Your total production for example. IP-safety is a key topic for visiting Bregenz for this Tech-Talk. Even packaging capacity is 1.8B pieces per month the years to come and a strong IP portfolio though Seoul Semiconductor (SSC) is a well which is a huge number but a necessity for is getting more and more important. known company in the field of SSL, could you the economy of scale. On the other hand the SSC invests around 10% of the annual please share a few important milestones of price reductions over the past years have revenue into global R&D activities. the company? been tremendous as well, haven’t they? LED professional: One technology which is Mr. Weisl: SSC’s history can be divided into Mr. Weisl: Due to market shifts there are always a topic of discussion is GaN-on-GaN roughly three phases since our CEO, Mr. Lee, overcapacities available in production. But the technology or nPola technology as SSC assumed office. The years 1992 to 2001 were massive price-reduction was not expected in calls it. What can you tell us about the the years spent establishing the company in such huge dimensions. A main driver for the nPola technology? the Korean marketplace. By the end of this price degradations is caused by governmental period, SSC had reached the number 1 LED subsidies in Asia. We are well prepared for the Mr. Weisl: The key point is that this manufacturer position in Korea. The years upcoming market consolidation. Factors such technology can increase the light output by a between 2002 and 2013 saw SSC developing as cost optimization, a lean organization and factor of 5-10 using the same chip size as for towards becoming a global player in the especially new competitive technologies will conventional LEDs and still keep the high lighting field. The current phase, from 2014 to help us to overcome these tough times. For the efficacy. In other words, we could reduce the 2019, is, and will be dominated by the goal of further development of the company our goal chip size by a factor of 5-10 and generate the becoming the world market leader as an LED is to at least double our market share from same light output as from conventional LEDs. component manufacturer and supplier. today’s 6-8% to 15% within the next years. At the moment the substrate is still expensive and that’s why we didn’t launch a product for Currently, SSC is number 6 in the global LED LED professional: Heavy investments are mass applications yet. The technology shows manufacturers’ ranking with a revenue of USD necessary in production to reach the market much better droop behaviour and is ideally 940M last year. If we exclude the captive goals. On the other hand, you’re confronted applicable for higher currents. Applications for market revenues from the top 5 LED with declining prices. Are there other spotlighting, wave-guides or automotive suppliers, SSC is #2 for white LED products. instruments that can help the industry and lighting would gain a lot from it. In general, With more than 10,000 listed patents and SSC in this situation? the manufacturing costs will have to come cross license agreements with global key down. The nPola technology is a future trend, players, in the areas of design, material and Mr. Weisl: The IP portfolio is an important especially for high-performance light sources, manufacturing methods, SSC was the only factor for further growth. More and more we and that’s why SSC is also doing research LED component manufacturer to be selected see that LED chip producers - tier 1 in this area. in the 2012 and 2013 Semiconductor manufacturers - are approaching module or Manufacturing Patent Power Ranking by the lamp manufacturers when they use LEDs LED professional: But that’s not for mass Institute of Electrical and Electronics which are not free-to-operate from the patent production, is it? Engineers (IEEE). The cooperations with the point of view. For example, a leading US LED Solid State Lighting and Energy Center manufacturer went to court against a big US Mr. Weisl: We do see three different strategic (SSLEC) of the University of California, luminary manufacturer last year due to a options for further developments in Solid- Santa Barbara (UCSB) and with SETI, a patent infringement of their Asian LED State-Lighting. Option 1 is the cost strategy, company working in the field of UV LEDs and supplier. We also filed a patent infringement option 2 the elimination of additional drivers which our subsidiary Seoul Viosys has lawsuit against a U.S. manufacturer one year and option 3 the quality strategy. The nPola recently secured the executive management ago. In July, the court finally issued the technology fits into option 3 for higher CRIs share from, are important strategic judgment in favor of Seoul Semiconductor. and “better white colors”. But also for partnerships for future developments. Prof. So, in fact, the companies who invested huge combined technologies for UV light sources. Nakamura from the UCSB and SSC have amounts of money in the development of In a second step it will also fit to option 1 been engaged in joint R&D for over 10 years. LEDs are now starting to protect themselves because 5-10 times more light output with the by approaching tier 3 manufacturers, same chip size as conventional LEDs will

THE MOST RECENT DOE FINDINGS ABOUT HV AC LEDS

Field Application Engineer at SSC, Lorenz Bauer explains the differences between AC driven systems. He also describes the huge step forward that Acrich 3 made in comparison to Acrich 2

The US Department of Energy further advances need to be made The US Department of Energy in (DOE) has forecasted in its annual in the total luminaire efficiency. its annual reporting continues to SSL R&D plan for 2015 that by The driver losses alone in a project direct AC LED technology 2030 approximately 80% of all luminaire could be 10% or greater and High-voltage LEDs as lighting fixtures in the US will be and failure rate of the drivers are as promising technologies in the LED lighting - which would result in high as 52%. The report mentions continued adoption of LED lighting. an annual energy savings of up to AC LED packages, such as Seoul For instance, in the study 395 TWh, a 60% reduction in Semiconductor’s Acrich conducted by the DOE in 2010 electricity consumption, which at a technology, that are designed to Seoul Semiconductor’s direct commercial price of $0.10/kWh run directly off the AC line power AC LED technology, Acrich MJT, would correspond to an annual and High-voltage LEDs, such as had energy savings of up to 86% savings of $40 billion. Seoul Semiconductor’s proprietary as compared to traditional lighting. MJT (Multi Junction Technology) In the 2015 report, DOE has While much progress has already LEDs, operating closer to the line again mentioned direct AC LED been made over the years in voltage as possible options to help technology and High-Voltage improving the efficiency of LED luminaire designers to reduce their LEDs as the next generation lighting systems to reach their fixture costs and further improve of light sources. full energy savings potential, on the efficiency of the luminaire.

result in cost reductions as soon thermal design by themselves. LED professional: How does this as substrate costs decrease. We are decidedly not making moves support work? towards integration for retrofits and LED professional: How does SSC luminaires and competing with our Mr. Weisl: We have built up so-called strategically position itself in the clients. SSC is one of only two LED small R&D labs in Munich, Shanghai, value chain? manufacturers who are sticking to Tokyo and Atlanta. These labs the pure component and module support application and design Mr. Weisl: We are a producer of business. We see this as a necessity - especially for custom-specific chips, packaged LEDs and LED in order to make our clients product designs. They are equipped modules. We don’t sell light engines successful by supporting them with modern measurement, design but mainly customized modules. on an engineering level. This was and layout tools which can be used Our customers still have to look after especially needed with our for Acrich or DC system developments. the right optical solution and the Acrich product line. Originally these labs where driven by

the support demand of the lighting products. So very specific LED professional: What about Acrich product segment. automotive LED solutions are Acrich3 and smart lighting necessary to fulfill the requirements technologies? LED professional: Let’s look at of the automotive market. the market portfolio. What are the Mr. Weisl: For Bluetooth, ZigBee and different market segments that LED professional: What are the core WiFi, there are special interface SSC delivers its products to? technologies at SSC now? modules for Acrich3, including sensors, available. The problem is Mr. Weisl: We have a strong Mr. Weisl: Latest key technologies that there is no standard dominating presence in three major segments; are our Acrich technology for the field yet but we’re offering namely Lighting, BLU & Mobile, AC & DC solutions and the NewGen, networking solutions for all major and Automotive. Actually, the BLU & which is our package-less LED controls. Our design support helps to Mobile part covers roughly 50% of technology, as well as the develop and create so-called our business while Lighting and module business including smart reference designs and then it’s up to Automotive are the strong growing lighting capabilities. the client if he’s going to produce areas. In Europe only the Lighting and source the module himself or if and Automotive segments are LED professional: If we take a closer SSC delivers the module through one relevant markets. The lighting look at the Acrich technology, what of our certified production suppliers, portfolio covers high and mid-power, are the latest developments? guaranteeing SSC quality COBs, high voltage and AC performance. For the smart lighting technologies. The AC business has Mr. Weisl: The Acrich3 IC solution is technologies, as well as the been growing significantly and based on a four-step bank switch production partners, we can access already represents one fourth of technology which increases the a high-quality standard process line our lighting business. forward voltage in steps, allowing for and partners. a quicker turn-on time and a better In the automotive market, we also match of the current to the voltage LED professional: Is this a kind of a focus on white LEDs and offer wave form. The base-technology are new business approach for the products specially developed for MJT chips but combined with an lighting industry? automotive applications. Although intelligent driving-IC for those our automotive business is still 4 channels. This solution generates Mr. Weisl: Price degradations, second to the lighting business in non-noticeable flicker and is suitable shorter development cycles, short terms of revenue distribution, we see for most general lighting applications, time-to-market periods and high high potential in this segment. even for street lighting. For very flexibility does make the business Currently in Europe, automotive sensitive applications, parallel quite difficult. The luminary accounts for 20% of our revenue with capacitors can smooth out the companies have built up SSL a strong indication that its share will flickering even more. For dimming knowledge in-house but they are increase in the future. Nevertheless, applications, the Acrich3 driver IC trying to focus on their core- the main part of our business will still has an additional 0-2 V analog competences. Solid partners, such be dedicated to general lighting, dimming input and an additional as SSC have to ensure IP-save, which is forecasted to have the power source for external sensors. high-quality and reliable solutions biggest growth rate. Globally, for the OEMs. LED based luminaires count for With this approach, systems from about 5% and are expected to have 4 to 200 watts can be realized, LED professional: SSC is exhibiting very high growth rates that will reaching power-factor values of at the LpS 2015. What can visitors to increase them to 70% within the over 0.97, which also stays nearly Bregenz expect to see from your next few years. constant over the full dimming range. portfolio? The system’s performance ranges up The global automotive lighting market to 130 lm/W on a lighting system Mr. Weisl: This year we will have a is about 1.6B USD and the exterior level. But taking into consideration double role. First of all, we’ll have a lighting segment is about 1B USD. that the driver electronics is booth in the exhibition area, and It has surpassed the interior part responsible for about 50% of all light secondly we will be presenting the since 2013. The daytime running source failures, the Acrich3 system is Acrich-based luminaires from our lights and the headlamps will count very reliable since it has no driver at “Out of Bounds Design Contest” in for about 50% of the exterior part all. Acrich3 was introduced to the the entry area. In this case our focus during the next years. That’s exactly market at the end of last year but will positively be on Acrich. the domain on which SSC is developments are continuing for focusing. An interesting trend is the AC LED technologies. A DoE report At our booth, besides showing the fact that LEDs for automotive lighting especially highlighted the necessity Acrich products for indoor and applications are more and more of going in these directions when outdoor lighting, we will also be differentiated from the general looking at future trends. presenting the smart lighting

Andreas Weisl presents capabilities of this technology. chance to talk directly with the point of view. The decisive advantage an experimental sample demonstrator luminaire. In addition to that, we will be showing students about their creations and is the absence of a converter. The luminaire by components for outdoor lighting and our staff will be on-hand to explain Complete new design possibilities Lucibel was adapted a preview of products that will be the technical details. open up because the converter no with an Acrich solution in connection with launched soon. Products like the longer has to be considered during various smart lighting NewGen, our package-less LED. LED professional: What was your the design process. There have also modules. The system In the foyer visitors will be able to see motivation to initiate the Design been a lot of improvements on the will be exhibited at the what is possible with Acrich when Contest with Prof. Peter Naumann technical side. LpS 2015 they look at the 17 luminaire and the University of Applied prototypes designed by students of Sciences Munich? By engaging with young, creative the University of Applied Sciences students who have no limits and Munich. In a four month long study Mr. Weisl: Some customers are still could work unreservedly with this project, the goal was to develop sceptical of AC driven LED solutions technology, we wanted to provide a luminaires that clearly show the and overlook the potential benefits platform to demonstrate what great advantages of Acrich technology. that this new technology can offer solutions can be realized with the The project was a complete success them. They often do not realize that design freedom enabled by Acrich. and the variety of high quality lighting this technology has been further By doing so, it was our goal to show designs was extremely impressive. developed over the past one to two established lighting manufacturers As part of the exhibition, we are also years and that a lot of progress has what excellent designs can be taking part in the “Design meets been made. After many years of achieved with new technologies like Technology” day. The official award development and optimization, AC-LED technology, and that in presentation ceremony will also be a AC LED solutions are ready for reality the barriers are not as high part of the program as will be viewing general lighting both from a technical as the perception today. the exhibits. Visitors will have a point of view as well as a design

RESEARCHCATEGORY PHOSPHOR TECHNOLOGIES 48

Al2O3 Coated Europium- Activated Aluminum Silicon Nitride for COB LED Technology

Eu2+ activated nitride phosphors have drawn much interest for solid state lighting because of their interesting photoluminescence. While they show excellent optical properties, they are hygroscopic and have the potential of being degraded by atmospheric moisture and high temperatures. A coating layer on the surface is an effective method to improve stability against moisture and oxidation. For use in chip on board technology, Nika Mahne, master student at the Institute of Inorganic Chemistry, A. Reichmann, B. Bitschnau, R. Fischer, from the Graz University of Technology, and F. Schrank from 2+ Tridonic Jennersdorf propose an approach where a CaAlSiN3:Eu [1, 2, 3] phosphor was coated with

Al2O3, obtained via a Brønsted precipitation reaction based on a solution-coating process from a mixture of aluminum halide with a base after annealing at a temperature of 400°C.

Eu2+ activated nitride phosphors Experimental 20 ml isopropyl alcohol, dried at 2+ like CaAlSiN3:Eu offer 1 g of uncoated phosphor material 100°C and annealed at 400°C in interesting photoluminescence (europium-activated calcium a tubular furnace under constant 2+ properties [1]. Among Eu aluminum silicon nitride phosphor N2 flow to obtain a homogeneous

doped red nitride phosphors [1, 2, 3]) and 80 ml isopropyl coating of Al2O3 according to used in solid state lighting, alcohol were sonicated while being figure 1. After annealing at 400°C 2+ CaAlSiN3:Eu was found to stirred vigorously for 20 minutes. the observed colour of the coated show excellent optical properties The aqueous educts solutions unexcited phosphor particles because of adequate thermal were prepared according to table changed from orange to brighter

stability, lack of environmental 1. 5 ml of the Al(NO3)3·9H2O (aq) turbid orange. In order to obtain

hazard, non-toxicity, high emission solution were added dropwise thick Al2O3 layers this procedure efficiency and high quenching via an automatic syringe pump was repeated three times with the temperature [2]. However, to the suspension. After 20 ml of same coated particles.

these materials are hygroscopic Al(NO3)3·9H2O (aq) and 20 ml of

and have the potential to be NaHCO3 (aq) were simultaneosly degraded by atmospheric added dropwise to the suspension Characterization moisture and high temperatures and stirred for additional 30 minutes, To look at the morphology of

under operation [3]. One of the to form Al(OH)3 on phosphor particles and to examine the

effective methods to improve its particles. The coated particles were efficiency of Al2O3 coating on the stability is to create a coating filtered via vacuum, rinsed twice phosphor SEM investigations were

layer on the surface of the with 20 ml H2O (D.I.), twice with recorded. For that reason the phosphor particles [4]. The coating Table 1: should be optically transparent, Al(NO ) ∙9H O Reaction time Preparation of aqueous 3 3 2 Name of experiment [mol/l] NaHCO [mol/l] [h:min] solutions for the and a precise quantity of 3 coating experiments coating must homogeneously Coated phosphor 0.09 0.03 1:35 cover the surface of the individual material 1 Coated phosphor phosphor particle [5]. Therefore, 0.35 0.12 6:50 inorganic materials such as material 2 Al O are usually chosen to Figure 1: 2 3 act as a coating layer on the 400°C Chemical equation Al(NO ) ·9H O + NaHCO  2 AL(OH) + side products  Al O + 3 H O surface of phosphors [5]. 3 3 2 3 3 2 3 2

sample had to be coated with a thin Excitation spectra and emission Results electrically conductive layer using spectra were measured in a range According to the material safety gold for the topography images and of 350-600 nm and 500-800 nm data sheet, the chemical content of carbon for the chemical analysis. with an excitation wavelength of the fine powdery orange coloured The SEM measurements were 465 nm. The samples were made starting material, contains carried out in a Tescan Performance from a slurry-mixture consisting of Ca3N2 30-40%, AlN 25-35% and

Nanospace (topography images of 200 mg phosphor, 200 mg Si3N4 30-40% doped with 0-5% the particles) and in an Ultra 55 polystyrene in 1000 mg chloroform, Eu2O3. However, due to its water, from Zeiss equipped with a silicon which was stirred for 1 h. The slurry acid and moisture sensitivity, drift detector (SDD) from EDAX was knife-coated on a PET-foil with it may generate ammonia gas by for energy dispersive X-ray a wet film thickness of 25 µm. contact with moisture. Figure 2 spectroscopy. For the examination Quantum efficiencies were measured shows the result of the Rietveld of the Al2O3 coating and the with an extra modular integrating refinement of powder X-ray data of chemical analysis a cross section sphere unit (Quanta-φ) using a filter coated nitride phosphor before was prepared. Therefore the powder in non-reflecting PTFE sample annealing. The material is pure was embedded in epoxy resin, holders. The used reference material phase europium-activated afterwards the sample was ground ZrO2 (Merck), possesses a similar calcium aluminum silicon nitride with on silica carbide paper finishing refraction index, shows a similar the chemical formula CaAlSiN3. with 4000 grit and was polished particle size distribution and no The corresponding sharp peaks using a 0.25 µm diamond paste. emission after excitation with visible are in good agreement

ATR-IR spectra were recorded on a light as compared to the phosphor. (ICSD 161796 CaAl0.54Si1.38N3). It has Bruker spectrometer (Alpha-P) in a Quantum effieciency and CIE color an orthorhombic crystal system with range of of 4000-375 cm-1 with coordinates were calculated with the space group Cmc21. mid-wavelength infrared radiation. the program FluorEssence. The phase compositions of Figure 2: uncoated and coated phosphor Crystal structure of materials were analyzed by powder nitride phosphor diffraction using CuKα radiation Ca (green), N (blue), (Bruker, D8 Advance, LYNXEYE Si (yellow), Al (light blue) Detector, Bragg Brentano Geometry). The phase purity before treatment and after treatment was evaluated by Rietveld refinement of the XRD patterns using the program X-PertHighScorePlus (PANalytical). The photoluminescence properties of uncoated and coated phosphor material particles were determined using a spectrofluorometer (Horiba Scientific Jobin Yvon Fluorolog-3) at room temperature equipped with a 450 W xenon CW lamp.

Figure 3: Powder diffractograms of coated nitride phosphor 1 before annealing process (left) and of coated phosphor material 1 from (right)

Figure 4: ATR-IR spectra of several sharp peaks in the finger coated phosphor print area from 800 cm-1 to 400 cm-1. material 1 annealed at Since the peaks cannot be ascribed 100°C to defined absorption peaks, the uncoated phosphor spectrum should function as a reference spectrum. Figure 4 shows spectra of uncoated phosphor and coated phosphor material 1 after coating process number 1, 2 and 3 after drying at 100°C. The broad absorption peak at 3400 cm-1 can be assigned to the symmetric and asymmetric stretch modes of water and 1640 cm-1 to the stretching and bending mode of water respectively [6]. The absorption peak at 1400 cm-1 can be dedicated to the bending vibration of the ν[O—H] bond in Table 2: at 100°C in Figure 3 (left). Lattice Al(OH) , not to residual moisture [6]. Lattice parameters of Uncoated Uncoated 3 uncoated phosphor nitride phosphor parameters did not change in material 1 phosphor material 1 general (Table 2). Therefore it can be Figure 5 shows spectra of the before and after said that the coating process did uncoated phosphor and coated annealing Space not change the host lattice and so phosphor material 1 after coating group Cmc21 Cmc21 educts react with each other, but process 1, 2 and 3 after annealing a [Å] 9,7917(1) 9,7927(1) not with the phosphor. at 400°C. The formation of Al2O3

b [Å] 5,6461(1) 5,6465(1) from Al(OH)3 can be confirmed due The XRD pattern shows no proof for to the lack of signal in the area c [Å] 5,0579(1) 5,0588(1) the complete formation of crystalline around 3400 cm-1 and new signals

3 -1 -1 V [Å ] 279,621 279,726 Al2O3 from Al(OH)3 after the at around 1330 cm , 1200 cm and annealing process (Figure 3). Only a 1150 cm -1 [6]. By comparing the α = β = γ 90° 90° very small peak at 38° 2θ indicates weight of coated phosphor material the presence of less than 0.5% 1 after drying at 100°C and 400°C a

The lattice parameters of the doped crystalline Al2O3 (ICSD 75479). loss of weight of around 13% was crystal (Figure 2) are as follows: Therefore it can be concluded that observed. This loss of weight can

the obtained coating layer is of be ascribed to the formation of H2O

• a = 9.7917(1) Å amorphous nature. Also an besides Al2O3. One trend can be • b = 5.6461(1) Å increased background indicates observed: compared to the • c = 5.0579(1) Å and amorphous parts, which was uncoated phosphor the intensities • a unit cell volume of 279.621 Å3 undergone a background correction. are decreasing due to the hydrolysis of uncoated phosphor through The XRD pattern of coated Figure 4 shows the ATR-IR spectra water and the formation of phosphor material 1 annealed at of uncoated phosphor and coated hydrolysis products during the 400°C (Figure 3, right) shows no phosphor material 1. The spectrum coating process. The inorganic significant peak changes compared of europium-activated calcium segment of the ν[Al—O—Al] band is to coated phosphor material 1 dried aluminum silicon nitride shows observed at 800-400 cm-1 and its

Figure 5 (left): ATR-IR spectra of coated phosphor material 1 annealed at 400°C

Figure 6 (right): ATR-IR spectra of uncoated phosphor material, coated phosphor material 1 and 2 after annealing at 400°C in the range of 1600-375 cm-1

RESEARCH PHOSPHOR TECHNOLOGIES 52

Figure 7: SEM image of uncoated phosphor material 1 at a magnification of 2.26kx (left) and a material contrast image of coated phosphor material 1, 200xBSE (right)

Figure 8: Material contrast image of coated phoshor material 1 particles 1000x BSE, 15 kV (left) and a single grain of coated phosphor material 1 at a magnification of 4000x BSE (right)

absorbance intensity increases elements (low atomic number like attractive forces overwhelm

with increasing amount of the Al2O3 O or Al), and thus appear brighter in repulsive forces. The formation of layer [6]. Unfortunately ν[Al—N] and the image, BSE are used to detect agglomerates can be prevented by ν[Al—O] signals are difficult to contrast between areas with changing the reaction conditions of distinguish because of the different chemical compositions. the synthesis like concentration of pronounced overlap of their bands. Therefore, the brighter areas in educts more specifically ion Figure 6 shows ATR-IR spectra of figure 7 (right) can be ascribed to concentration and temperature.

uncoated phosphor material, coated the CaAlSiN3 phosphor and the phosphor material 1 and 2 after the darker areas to the precipitated Figure 9 (left upper corner) shows a

annealing process in the range of Al2O3 and the dark background to material contrast image of coated 1600-375 cm-1. Approximate trends the epoxy resin matrix. With larger phosphor material 2. The elements can be observed: decreasing magnification no homogeneous determined by EDX are dyed in

absorbance intensity and formation coating with Al2O3 on phosphor different colours and labeled in the of new bands in the area between particles can be observed upper right corner of the pictures. 900-375 cm-1 were observed, (Figure 8, left). In figure 9, phosphor Ca (turquoise), Al (yellow), but larger absorbance intensity for particles with an inhomogeneous Si (magenta) and N (green) are found coated phosphor material 1 in the coating can be observed thereby in the brighter areas. Al (yellow) and area from 650-550 cm-1. showing two different modifications O (blue) are also found in the darker

of Al2O3, one with agglomerates areas around the brighter areas The morphological analysis of (area 2) and one with single particles (phosphor), according to the

uncoated phosphor is shown in (area 3). Beside that particles and formation of an Al2O3 layer. In

Figure 7 (left) and exhibits single agglomerates of Al2O3 are indicated. contrast to phosphor material 1

particles with cylindrical structure Figure 9 (right) shows an almost no completely intact layer of Al2O3

(particle size distribution of 5-15 µm). intact Al2O3 coating of a single was observed on coated phosphor Figure 7 (right) reveals a material particle with an irregular layer material 2. Figure 10 shows the contrast image of the fabricated thickness up to 4 µm. The formation obtained EDX spectrum of the

cross section of Al2O3 coated of different Al2O3 modifications was coated phosphor material 1, phosphor particles 1, caused by caused by the reaction conditions. particular elements of the

backscattered electrons. Since The synthesis of Al2O3 coating on phosphors host lattice show heavy elements (high atomic the phosphor was done in excess of significant peaks of Ca, Al, Si and N.

number like Ca, Eu) backscatter educts Al(NO3)3·9H2O and NaHCO3. Peaks of O and C can be assigned electrons more strongly than light Agglomerates are formed when to the epoxy resin matrix.

RESEARCH PHOSPHOR TECHNOLOGIES 54

Figure 9: Coated phosphor material 2 at a magnificastion of 1000x BSE

Figure 10: EDX spectra of coated phosphor material 1, area 1, area 2 and area 3

Noticeable changes are observed in the NUV region. The excitation peak change after the coating process. peak intensities of the elements like corresponding to Eu2+ extends A hypsochromical shift occurred

shown in figure 9 of area 1, area 2 towards the visible region with a with increasing number of Al2O3 and area 3. The results of the BSE maximum at 430 nm. On this coating steps (Figure 11, Table 3). image determined area 1 as the account the phosphor can be This could also be caused by the host lattice of the phosphor, excited by conventional LED chips used sample preparation method. therefore peaks for Ca, Al, Si and N and is therefore suitable for use in Although the samples were made in are found, but also a high peak of C chip-on-board technology. the same way, the comparability can 2+ and a peak for O which stem from The CaAlSiN3:Eu phosphor shows not be assured because the layer the epoxy resin. Area 2 shows a a broad symmetric single band in thickness could vary and hence a significant peak for Al and a larger a range of 500-800 nm with an diverse concentration in the film can peak for O than in area 1 due to the emission maximum at 643 nm which occur. Affirmative an oxidation of 2+ 3+ formation of Al2O3 after the coating is typical for a 5d-4f transition of Eu to Eu was not observed. and annealing process. Based on Eu2+ [3]. It covers a part of the visible The minimal shift of 3 nm of the the obtained peaks in area 3 both light in the area between 550 nm emission maximum caused a

epoxy resin and Al2O3 are and 750 nm (blue LED-Chip) and it negligible shift of CIE colour coexistent. Area 2 and area 3 have is therefore a well suited phosphor coordinates (Figures 11&12, Table 3). similar spectra. They only differ in for use in chip-on-board technology. Furthermore a reduction of the

agglomeration of Al2O3. Area 3 The visible emission colour of quantum efficiency of coated contains more epoxy resin less uncoated phosphor is deep red. phosphor material 1 compared to

Al2O3, area 2 more Al2O3. After the coating process the untreated phosphor occurred. emission colour of unexcited Figure 11 shows the excitation and particles changes from orange to The quantum efficiency (QY) emission spectra of uncoated brighter turbid orange, which can be compared to uncoated phosphor phosphor material at. The excitation ascribed to a not absolutely optically decreased for 13% of coated spectrum shows a broad peak from transparent precipitated layer of phosphor material 1 and for coated

the NUV to the VIS area with a peak Al2O3. Emission spectra of uncoated phosphor material 2 for 16%. maximum at 352 nm. The excitation phosphor material and coated The reduction of the quantum of the host lattice and further energy phosphor material 1 are compared efficiency of coated phosphor transfer to the dopant Eu2+ can be in figure 11. The shape and the material 1 could be caused by the

ascribed to the peak maximum in width of the emission band did not thick layer of Al2O3 on the particles.

RESEARCH PHOSPHOR TECHNOLOGIES 56

Figure 11: Excitation and emission Moreover the images taken with spectra of uncoated SEM indicate the fact that phosphor and coated phosphor particles were embedded in a matrix material 1&2 with an of Al O and besides that the XRD emission maximum of 2 3 638 nm and 643 nm analysis determined that the obtained coating is of amorphous nature (Figure 3). Therefore diffuse

scattering of light at the Al2O3 layer may result in reduced excitation of Eu2+ and diminished quantum efficiencies.

Conclusion In summary, we have demonstrated

a route to coat CaAlSiN3 phosphor. In regard to the use of coated phosphor particles in chip-on-board Figure 12: CIE Diagramm of technology, the coating procedure uncoated and coated itself does not influence the phosphor materials 1&2 emission spectra seriously, no mentionable colour shift occurred (Figures 12&13). Moreover a colour shift due to an oxidation of Eu2+ to Eu3+ could not be observed. The ATR-IR analysis confirmed the

transformation of Al(OH)3 to Al2O3 after annealing it at a temperature of 400°C. The XRD analysis showed the amorphous nature of the formed

Al2O3 coating.

Table 3: Luminescence Sample λMAX, emission [nm] x y QY [%] properties of uncoated phosphor and coated Uncoated phosphor 643 0.6625 0.3371 75 phosphor material 1&2 material

Coated phosphor 640 0.6569 0.3427 65 material 1

Coated phosphor 643 0.6563 0.3432 63 material 2

Accknowledgements: Thanks to Tridonic Jennersdorf GmbH who enabled me to work on that forward-looking topic in the course of my Master Thesis at Graz University of Technology. Thanks to Sergey Borisov from the Institute of Analytical Chemistry and Food Chemistry at Graz University of Technology. This work was supported by a grant from the Austrian Forschungsförderungsgesellschaft FFG, Projekt Nr. 842562.

References: [1] Piao X., Machida K., Horikawa T., Hanzawa H., Shimomura Y., Kijiama, N.; Chem. Mater. 2007, 19, 4592-4599 [2] Kim H.S., Horikawa T., Hanzawa H., Machida K. J.; Phys.: Conf. Ser. 2012 379 012016 [3] Uheda K., Hirosaki N., Yamamoto Y., Naito A., Nakajima T., Xamamoto H.; Electrochem. Solid St. 2006 9 (4) H22-H25 [4] Sun J., Sun R., Du H; Appl. Surf. Sci. 2012 258 4569-4573 [5] Zhuang J., Xia Z., Liu H., Zhang Z., Lia L.; Appl. Surf. Sci. 2011 257 4350-4353 [6] Ghezelbash Z., Ashouri D., Mousavian S., Ghandi A.H., Rahnama Y.; Bull. Mater. Sci 2012 Vol. 35 No. 6 925-931

RESEARCHCATEGORY GRAPHENE BASED LEDS 58 A Graphene-Based, Spectrally Tunable, Flexible Field-Effect Light-Emitting Device

The continuous tuning of the emission spectrum of a single light-emitting diode (LED) by an external electrical bias is of great technological significance as a crucial property in high-quality displays and may be used in high quality lighting applications, yet this capability has not been demonstrated in existing LEDs. Graphene, a tunable optical platform, is a promising medium to achieve this goal. Xiaomu Wang, He Tian, Mohammad Ali Mohammad, Cheng Li, Can Wu, Yi Yang, and Tian-Ling Ren from the Institute of Microelectronics at the Tsinghua University in Beijing and the Tsinghua National Laboratory for Information Science and Technology (TNList) demonstrate a bright spectrally tunable electroluminescence from blue (~450 nm) to red (~750 nm) at the graphene oxide/reduced-graphene oxide interface.

The solid-state light-emitting it potentially provides a way In this article, we demonstrate diode (LED) is a key component to in situ control the color of a desirable combination of of today’s semiconductor LEDs. Although various high- a bandgap structure and a industry1. The successful performance graphene-based bipolar carrier injection in a development of LEDs has photonic devices have been special type of semi-reduced enabled plenty of applications reported [13, 14, 15, 16, 17], graphene oxide (GO). such as high-performance unfortunately the development Our device formed on a laser- communication, low-cost of graphene-based LEDs has scribed GO surface consists of lighting and smart displays. been unsuccessful owing to its a series of rGO nanoclusters In modern LED industries, vanishing bandgap. with many different sizes, which controlling the color of LEDs is can selectively stimulate a a challenging task [2, 3, 4, 5, 6]. A plausible strategy for realizing single-color luminescence by Traditional LEDs are available electroluminescence (EL) may controlling its doping level. in different predefined colors be by creating discrete energy The semi-reduced GO network whose emission wavelength levels by utilizing functional is with a mobility approaching is adjusted by complex groups, quantum confinement 10 cm2 V-1 s-1, which supports material design and bandgap effect or other mid gap states. the carrier injection. We report engineering. To date, the in situ Unfortunately, the insulating the observation of EL in these controlling of color in a single nature of the photoluminescent semi-reduced GO-based device has never been realized, graphene derivatives, such devices. The light-emission although it is highly desired. as functionalized graphene spectrum in our device is in Graphene and its derivative or solution-based graphene situ adjusted from blue material-based photonic devices quantum dots, negatively (λ ~ 450 nm) to red (λ ~ 750 nm) are currently the focus of intense affects the carrier injection by electrical gating or study [7, 8, 9, 10, 11, 12]. and disables EL. In summary, conditioning the environmental Graphene is an amendable a method to fabricate a doping. The device shows platform whose electronic graphene-based device with a high brightness of up to and optical properties can a non-vanishing bandgap and 6,000 cd m-2, with efficiency be tailored by chemical and charge injection capability is around 1%. electrical means. This property still lacking. is particularly interesting as

Figure 1: Results GFLED and characterization Fabrication and characterization of field-effect LED Figure 1a schematically shows the structure of our all-graphene-based field-effect LED (GFLED). A planar side gate graphene field-effect transistor device was first prepared based on a laser-scribing method (see Methods for details) [18]. The light-emitting layer, which is the interface between the GO and rGO, was then uncovered by using current annealing to remove the highly conductive rGO channel. The typical length of the light- emitting region is 80-120 μm and is located in the centre of the narrow graphene field-effect transistor channel. This central location is determined by the geometric design as the Joule heating rapidly affects the narrowest part of the structure. It is worth mentioning here that the fabrication process was carried out in ambient conditions and does not require any high-vacuum environment, hazardous solution or high-temperature treatment.

Figure 1 shows the GFLED principle and characterization: The exposed interfacial layer showed very broad PL, • Schematic of the GFLED. A obtained by this method presents ranging from about 470 to more distinct semi-reduced GO (blue) at three major differences as than 720 nm (with ~0.8 eV full-width the interface between GO (orange) compared with GO or rGO. at half-maximum). and rGO (gold) is responsible for First, this interfacial layer is ultra-flat. light emission (a) The RMS thickness obtained from Generally speaking, the zero- • PL spectrum of light-emitting atomic force microscope is several bandgap nature of rGO results in layer. The D and G Raman peaks orders smaller than that of GO or a large non-radiative decay rate are marked. Inset: Raman spectra rGO. Second, the interfacial layer is of stimulated electron-hole pairs, of the GO and rGO samples. colorful, this is in stark contrast to while the energy gap between The GO and rGO samples do not the white colour of GO and the the π and π* bands of GO is show any PL signals (b) black colour of rGO. Third, extremely large. All these factors • X-ray photoemission and perhaps most importantly, a imply that luminescence in rGO spectroscopy spectra of rGO strong and broadband and GO should be impossible. (red), GO (green) and the light- photoluminescence is solely The experimentally observed broad emission layer (black). Spectra observed in the interfacial layer, as PL feature is a strong signature of from the C1s and O1s orbitals are shown in figure 1b (supplementary the presence of localized states, shown (c) Figures 1-4 and Supplementary similar as those in rGO quantum • Bright red light emission from the Note 1 for detailed comparison dots [19, 20]. These localized states GFLED on a flexible polyethylene between the interfacial layer and can be understood by the formation terephthalate (PET) substrate bulk GO/rGO). The photo- of a transition state during the under a 12 V bias voltage and a luminescence (PL) spectra of the reduction process: There is a 0.1 A drive current. The GFLED GO/rGO interfacial layer were distinct partially reduced GO layer size is around 100 × 100 μm. obtained by exciting the samples between the GO precursor and the The edge of the bent PET is with a continuous wave 457 nm thermally induced rGO as a result of marked by a dashed line. laser with low excitation power the laser dosage gradient from the The bending radius is ~8 mm (d) (~100 μW). The interfacial layer surface downwards.

Figure 2: Electroluminescence We performed X-ray photoemission properties of GFLED spectroscopy to further characterize the chemical composition of the light-emitting layer. A collection of X-ray photoemission spectroscopy spectra is shown in figure 1c. Fundamentally, the light-emitting layer can be identified as an intermediate state between GO and rGO in terms of oxygen concentration. The C/O ratio for rGO, the interface layer and GO is 2.10, 0.77 and 0.57, respectively. The chemical states of carbon and oxygen in different layers also show pronounced variation. The C1s spectra of GO and rGO are similar as per the previously reported typical results [21]. For the GO case, Incident laser stimulates electron- 20 devices to characterize the in addition to a large carbon peak hole pairs in the π band and bias-dependent EL intensity. composed of graphitic sp2 and sp3 in these discrete states. Typical relative emission intensity C-C bonds, another C-O clear peak Radiative recombination of the versus different drain bias and the can be observed due to the electron pairs thus gives rise to a EL intensity distribution are plotted hydroxyls and epoxies. For the rGO PL effect (and also leads to EL, in figures 2 a&b, respectively. case, the spectrum is dominated by see discussion below). In this case, Notably, the EL intensity is the graphitic sp2 component and the degree of reduction of the rGO controlled by drive current. the C-O bonds only show a very determines the features of the PL As shown in figure 2b, the devices minute component. However, the spectrum, similar to how porous are relatively uniform under a fixed

interfacial layer exhibits distinct silicon and colloidal quantum dot 0.1 A current bias (Imax/Imin < 2). features as compared with the GO devices affect the spectrum [6, 23]. In contrast, the relative EL intensity and rGO. In addition to an presents large device to device

intermediate carbon-carbon bond variation (Imax/Imin ~ 10) under a state, the interfacial layer is also rich Spectrally adjustable EL fixed 12 V voltage. in C=O bonds. These bonds are Once the energy levels with usually attributed to carbonyls. bandgaps are created, EL can Figure 2 shows GFLED’s The presence of carbonyls in the be expected if bipolar carriers electroluminescence properties: GO basal plane signifies incomplete are injected into the device. reduction [21]. A similar feature of Previously reported “gapped • Source-drain current (circles) and the transition state was also graphene” (such as GO and EL intensity (solid squares) versus observed in the O1s spectra. graphene quantum dots) is either an source-drain bias voltage. While rGO and GO are dominated insulator or a liquid-phase material, The device used has a W/L ratio by C=O and C-O peaks, which impair the carrier injection. around 0.1/0.1 mm. The solid line respectively, the light-emitting layer Fortunately, the interfacial layer shows the Poole-Frenkel fitting of is a mixture of C-O and C=O bonds. (although also a type of GO), is a the drive current. The EL peak is at The two-component configuration p-type semiconductor with a good 690 nm. Inset: source-drain current has been used to characterize the conductivity (Figure 2a inset; versus gate voltage of the same transition state in the evolution of also see Supplementary Figures 5-7 device, showing a p-type field effect (a) reduction of GO [22]. and Supplementary Note 2 for • Histogram of EL intensity characterization of its field effect). distribution under fixed voltage As described above, the interfacial In addition, an enhanced carrier and current bias. The data have layer is a special type of partially injection was also identified under been obtained from 20 devices (b) reduced GO. Generally speaking, a strong bias field, manifested by • Typical EL spectra of a single GFLED. the reduction of GO leads to the rapidly increasing current Gate biases are from 0 to 50 V (c) creation of small (2-3 nm) ordered versus bias voltage in figure 2a. • Peak position (wavelength) and sp2 clusters isolated within the Accompanied by the pronounced intensity of the GFLED EL versus sp3 C-O matrix of GO7. Therefore, free carrier injection process in the gate voltage. The data have been the partially reduced GO likely device, we observed EL along the collected from 19 devices. results in a series of discrete energy interfacial layer. The emitted light is Error bars (standard uncertainty) levels between π and π* bands by bright and easily identified by the are estimated from the device quantum confinement effect [19]. naked eye (Figure 1d). We fabricated variations (d)

RESEARCH GRAPHENE BASED LEDS 62

Figure 3: GFLED light-emission harvested, which suggests that the mechanism efficiency upper limit of GFLED is 25%. Therefore, the promotion of efficiency requires improved carrier injection and introducing intersystem crossing in future works.

EL mechanism Next, we proceed to discuss the possible EL mechanism. The simultaneously rapid increase of the current and EL intensity clearly indicates that carrier injection plays a central role in the EL process. Owing to the p-type nature of the light-emitting layer, electron injection An exceptional observation in this was measured under a 16.5 V bias is the key factor of understanding work is that the colour of EL and a 0.1 A drive current. Overall, the EL process. At the current state, emission can be continuously tuned the broad PL can be roughly the exact mechanism of electron from light blue to dark red by regarded as the envelope of all injection is not well known. On the adjusting the Fermi levels. The Fermi these possible EL spectra. basis of the various evidences, level and the doping level of the This strongly suggests that the EL we hypothesize that the electric GFLED can be modulated either results from a selective excitation of field-assisted thermal ionization, electrically or chemically. In this inhomogeneous luminescence of also known as Poole-Frenkel paper, we use a side gate field to semi-reduced GO, as observed in emission, is the most probable control the Fermi level; however, previously reported rGO quantum mechanism. the colour also changes in response dots. A possible explanation of the to ambient doping, enabling sensing field effect-modified EL will be We performed temperature- applications. Typical emission discussed in the following part. dependent electrical measurements images, spectra recorded at to investigate the electron injection different side gate voltages during Currently, the efficiency of GFLEDs process. Figure 3a shows the the EL measurement and spatially is relatively low. We hypothesize that Poole-Frenkel plot of I-V resolved EL are shown in figures 1d two factors limit the efficiency. characteristics of a typical device. and 2c and Supplementary Figure 8. First, as shown in Supplementary As illustrated in the inset of figure 4, The EL peaks exhibit sharp single Figure 9, the efficiency tends to a linear relationship fits well to the Lorentzian shapes. As shown in saturate at a large current density. measured conductivity in the figure 2c, the peak emission We attribute this saturation to the Arrhenius plot, indicating the wavelength shifts from 690 nm at inefficient injection of electrons electrons inject into the system on a zero gate voltage to 470 nm under caused by heat dissipation, that is, charge emission manner. The highly 50 V gate voltage. On one hand, much of the supplied power is lost linear feature in the log(I) versus the EL peaks present similar narrow to heat dissipation. In other words, V1/2 plot signifies the I-V curves full-width at half-maximum (~0.2 eV), the saturation is caused by the agree well with the Poole-Frenkel whereas on the other hand, inefficient injection of electrons current law (see Supplementary the relative intensity of the EL (discussed below). The large amount Note 3 for details) [24]. The Poole- is found to vary under different of heat dissipated can also break Frenkel effect is usually understood bias voltages. For instance, the devices rapidly. The emission as a means by which trapped the maximum luminance and the lifetime of these devices are several electrons get out of Coulomb luminous efficacy of the blue light tens of seconds in ambient binding and move to the conduction are much lower than the red light. conditions. This short lifetime can band. Figure 3a schematically Approximately 4.8 lm/W be attributed to vigorous oxidation in shows how this effect applies to the (corresponding to ~0.7% external air. However, these devices have a GFLED. The oxide-rich light-emitting quantum efficiency, also see much longer half-life in vacuum and layer has a high density of electron Supplementary Figures 9 and 10 for tests have revealed continuous and trap states. Under high field, details) and 6,000 cd /m2 red and stable emission for up to 2 h, the localized electrons are excited green lights were measured under a suggesting protective coatings may into the lowest unoccupied discrete 12 V bias and a 0.1 A drive current, help to avoid structural damage in energy level. Radiative whereas 0.67 lm /W (corresponding practical devices. Second, in the recombination between the to ~0.1% external quantum absence of an intersystem cross thermally emitted electrons and efficiency) and 800 cd /m2 blue light path, only singlet excitons can be the free holes results in the EL.

RESEARCH GRAPHENE BASED LEDS 64

Figure 4: GFLED two-terminal Therefore, the observed positive temperature-dependent temperature coefficient clearly rules transport out the impact ionization mechanism.

Discussion In summary, we have reported the design and implementation of a LED device based on a special type of semi-reduced GO that forms in the rGO/GO interface. By yielding a series of discrete energy levels between the π-π* gap and injecting free carriers into those states, EL is successfully achieved. The in situ tuned wavelength of the EL exemplifies a kind of novel light- emitting device that is highly desired Figure 3 demonstrates the GFLED determined by the distribution of for high-color-quality displays and light-emission mechanism: density of states of the discrete high-quality lightings. The precise energy levels. spectral tunability, compact device • A schematic of the charge structure, high performance and injection process. The trapped Several mechanisms, such as straightforward fabrication point to electrons are excited to the lowest thermal emission [25], Fowler- the commercial prospects of such unoccupied discrete energy level Nordheim tunneling [26, 27] and a device. We anticipate our findings by Poole-Frenkel emission. impact excitations [28, 29, 30] may to be a prospective point for The excited electron recombines also cause the EL in the GFLED. commercialization of graphene with the hole in the π band, However, none of them can devices. Furthermore, resulting in photon emission (a) consistently explain all the findings the observance of EL itself • Schematic of the gate voltage- of this work. Here we discuss the addresses the lack of a light source dependent EL. The Fermi level validity of these possibilities to component in graphene-based determines the lowest unoccupied GFLEDs. First of all, the featureless photonic devices, paving the way energy state that mainly electroluminescence peak would for all-graphene integrated participates in the radiative correspond to a local temperature photonics. This device opens the recombination. above 4,500 K if the EL results from possibility of fabricating carbon- Inset: corresponding emission blackbody radiation coming from based photonic devices due to images from a real device (b) Joule heating. This would rule out the henceforth availability of thermal emission as the light- graphene-based LEDs. Figure 4 shows the source-drain emitting mechanism. Second, current versus voltage bias at Fowler-Nordheim tunneling, different temperatures: which is a main charge injection mechanism in porous silicon EL • The current is limited to 0.1 A device, may also work for the to avoid device breakdown. GFLED [26]. Considering the planar Inset: Arrhenius plot of source- device structure, the tunneling drain current at bias voltages of process most likely occurs around 2, 4, 6, and 8 V the drain electrode that holds the largest band bending. However, This mechanism also explains the this contradicts the light emission observed spectral shift, as shown in observed in the middle of the figure 3b. Gating graphene lifts up device. Finally, impact excitation/ the chemical potential and thus the ionization is another plausible energy level of the lowest EL mechanism and has been used unoccupied discrete state; to successfully describe the EL therefore, the excited electron phenomenon in carbon nanotubes energy is increased. Through this [28, 29, 30]. However, the threshold way, the EL peak can be adjusted voltage in an impact ionization within the whole PL range; and the process is always accompanied by relative emission intensity is a negative temperature coefficient.

Methods:

Sample preparation GFLEDs were fabricated based on a side gate field-effect transistor structure. An ~1 μm thick GO (XFNANO Materials Tech) film was prepared by drop casting on a flexible polyethylene terephthalate substrate. Conductive rGO traces with ~100 μm width were then patterned by a previously reported laser-scribing method within a DVD drive [31]. Silver paste electrodes were fabricated to improve the contact. In the scribing process, the DVD drive’s 788 nm laser (5 mW) was used to gradually reduce the stacked GO films to rGO. After that, the as-prepared devices were annealed by a 10 mA current to expose the interfacial layer.

Electrical measurement Electrical measurements were carried out within a Lakeshore CPX-VF-457 cryogenic probe station using a Keithley 4200 semiconductor analyser. Electrical doping were achieved by using a side gate that surrounds the GFLED. The GO acts as a dielectric with a capacitance of 160 nF (see Supplementary Figure 5 for details).

PL and EL measurements The luminescence measurements were performed using a Renishaw inVia micro-Raman spectroscope equipped with 457, 514 and 633 nm lasers. The spot diameter was around 1 μm under a × 100 objective lens. For PL measurements, the laser powers was set at 100 μW to avoid breaking the samples. The typical integrating time was 10 s. For EL measurements, a dual-channel Keithley 2612 source meter supplied the electrical and gate bias.

Acknowledgements/Citation: This work was supported by National Natural Science Foundation (61434001), 973 Program (2015CB352100), National Key Project of Science and Technology (2011ZX02403-002) and Special Fund for Agroscientic Research in the Public Interest (201303107) of China. We are thankful for receiving support through the State Key Laboratory of Automotive Safety and Energy, Tsinghua University. H.T. is thankful for receiving support through the Ministry of Education Scholarship of China. M.A.M. is thankful for being supported by the postdoctoral fellowship (PDF) programme of the Natural Sciences and Engineering Research Council of Canada (NSERC).

Article citation Wang, X. et al. A spectrally tunable all-graphene-based flexible field-effect light-emitting device. Nat. Commun. 6:7767 doi: 10.1038/ncomms8767 (2015). http://www.nature.com/ncomms/2015/150716/ncomms8767/abs/ncomms8767.html http://creativecommons.org/licenses/by/4.0/

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Author Footnotes: Xiaomu Wang1,2,*,W, He Tian1,2,*, Mohammad Ali Mohammad1,2, Cheng Li1,2, Can Wu1,2, Yi Yang1,2 & Tian-Ling Ren1,2 1 Institute of Microelectronics, Tsinghua University, Beijing 100084, China 2 Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing 100084, China * These authors contributed equally to this work. W Present address: Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, USA. Correspondence and requests for materials should be addressed to T.-L.R. (email: [email protected]).

Competing financial interests: The authors declare no competing financial interests.

Licensing: This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

SUPPLEMENTARY NOTES AND FIGURES

Supplementary Note 1: Comparison between GO, rGO and their Interfacial Layer The interfacial layer between GO and rGO presents a totally different morphology and chemical properties as compared with both materials. The photograph of the interfacial layer exhibits a color - this is in contrast to the white color of GO and the black color of rGO, as shown in Supplementary Figure 1.

To further examine the light-emitting Supplementary Figure 1: GO, rGO and GO/rGO interfacial layer. Images of (a) rGO on GO interficial layer, we performed nanoscale prepared by laser scribing, and (b) the interfacial layer morphology analyses using AFM. The microscopic morphology present distinct features for the interfacial layer (Supplementary Figure 2) and GO (Supplementary Figure 3). Firstly, the interfical layer has a very small roughness (RMS 0.594 nm) in comparison with GO (4.28 nm). Secondly, several tiny and distinct ripples are recorded in the interfacial layer.

Supplementary Figure 2: AFM images of the GO/rGO interfacial Layer. (a) The topography and Finally, PL measurements were also (b) corresponding phase image are both shown carried out for GO and rGO, as shown in Supplementary Figure 4. As discussed in the main text of the manuscript, both GO and rGO present pronounced Raman signals only. Although a very weak and broad PL spectrum was observed in the rGO samples, it likely arises from the interfacial layer underneath the rGO. We believe this to be the case as the PL spectrum is strikingly similar to what was observed previously from the interfacial layer. It should be noted that due to the Supplementary Figure 3: AFM images of the GO. (a) The topography and (b) corresponding phase image are both shown strong resonance energy transfer, graphene (and rGO) presents a strong luminescence quenching effect, suggesting the current annealing step is necessary for the rGO QD LEDs.

Supplementary Note 2: Field-Effect Characteristics of the GFLEDs Firstly, we directly measured gating efficiency in our device based on a capacitor configuration which is similar as the Metal-Insulator-Semiconductor structure. As shown in the inset of the Supplementary Figure 5, we fabricated a capacitor by the laser scribing method. The two rGO regions were defined as two capacitor electrodes, which in our device Supplementary Figure 4: PL measurements of GO and rGO

act as the side gate and source electrode respectively. The C-f measurement of this structure clearly demonstrates our structure is with a capacitance around 4 × 10-4 F/m2. For comparison, we also measured the

capacitance of 300 nm SiO2 substrate, which results in a 1.15 × 10-4 F/m2 capacitance. After that, the electrical and optical characteristics of GFLED under gate bias are illustrated in Supplementary Figure 6.

Supplementary Note 3: Poole-Frenkel Modeling of the I-V Curve of GFLED The I-V curve of the GFLED obeys a Poole-Frenkel relationship which describes the conductance of electricity in an electrical insulator. The physical process Supplementary Figure 5: Capacitance of GO dielectrics. C-f measurements were carried can be understood within a release of free out on a Metal-Insulator-Metal structure. The two rGO regions were defined by laser- scribing as two capacitor electrodes, which in the GFLED act as the side gate and carriers from deep traps. In the insulator, source electrode respectively the electrons are generally trapped in localized states. Injected holes are accelerated by the strong electric field in the insulator and will transfer that electron enough energy to get out of its localized state, and move to the conduction band.

In this process, the source-drain drive current fits well to

-q ∙ (ΦB - √(qE / πε) I ∞ E exp( ) (1) kB ∙ T

where q is unit charge Supplementary Figure 6: Electrical Characteristics of GFLED (a) Transfer Curves of a typical GFLED under different source-drain bias (b) Output Curves of a typical GFLED under different k is Boltzmann constant B source-drain bias T is temperature

ΦB is zero-bias built in potential between the metal and rGO QDs, and ε is electrical permittivity

The average applied electric field E can be expressed as

1 E = ∙ (V - l ∙ R ) (2) l S

in which

V is the voltage across the LED l is the device channel length, and

RS is the parasitic contact resistance

Supplementary Figure 7: Gate-Dependent PL of a typical GFLED

Supplementary Figure 8: Spatial resolution of GFLEDs. Spatially-resolved EL of (a) a working device and (b) the as-prepared device. (c) PL mapping at 530, 600 and 670 nm illustrate the emission sites of the device. (Scale bar: 100 μm)

Supplementary Figure 9: Efficiency of a GFLED as a function of current density

Supplementary Figure 10: Efficiency of a GFLED as a function of gate voltage

The availability of reliable and accurate photometric data for LED devices is a basic requirement for designing good lighting systems, evaluating performance of products and comparing data between different laboratories. Peter Blattner, Head of Laboratory at METAS and Chairman of the Technical Committee of Photometry and Radiometry of the European Association of Metrology Institutes explains how to measure products and how to interpret data regarding measurement uncertainties and manufacturing tolerances according to the new new ISO/IEC Guide (Guide 98-4:2012). Furthermore, he discloses how to implement these guidelines in the industrial practice.

Conformity decisions are Introduction In conformity assessment usually a usually taken on the basis Conformity assessment is a key measurement result is used to of measurement results. element in product testing, industrial decide if an item of interest As a consequence of the quality control or legal requirements conforms to a specified measurements uncertainty for ensuring health and safety. In the requirement. If the measurements these compliance statements field of light and lighting many cases were “exact”, hence without cannot be made with absolute of conformity assessments can be measurement uncertainty, the certainty. Similar to the cited. conformity assessment would be evaluation of measurement straightforward: a measured value uncertainty standardized Some examples: would be considered compliant if it procedures are needed for is within the tolerance interval. In conformity statements. In 2012 • The European Regulation practice all measurements are the Joint Committee for Guides 1194/2012 requires that the lamp subject to a measurement in Metrology JCGM published power factor for LED-lamps with uncertainty. In this case accepting a guidance document (JCGM integrated control gear and lamp or rejecting an item when the 106) addressing conformity power larger than 25 W has to be measured value of its property of assessment and measurement larger than 0.9 interest is close to a tolerance limit uncertainty in general. The new • According to the EU Regulation may result in an incorrect decision international LED measurement 244/2012 the UVA+UVB content and lead to undesirable standard CIE S025:2015 (i.e. ultraviolet hazard efficacy of consequences. The presence of published recently by the luminous radiation) of compact measurement uncertainty requires a Commission Internationale fluorescent lamps shall be smaller more nuanced assessment taking d’éclairage (CIE) follows the than 2.0 mW/klm into account the risks for the international recommendations. • IEC 62471 (photobiological safety producer and the consumer. In of lamps) classifies lamps order to perform conformity according to the potential assessment in a unified way the photo-biological hazard into risk Joint Committee for Guides in groups Metrology JCGM, consisting of • LEDs are usually binned by the different standardization, manufacturer for luminous flux accreditation and metrology and chromaticity organizations including the Bureau International des Poids et Mesures (BIPM), the International Electrotechnical Commission (IEC),

Figure 1: the International Organization for Tolerance interval Standardization (ISO) and the to define specific International Laboratory requirement. TL and TU Accreditation Cooperation (ILAC) are the lower limit and upper limit respectively has published in 2012 the guidance document JCGM 106:2012 [1].

This guide gives a clear Figure 2: mathematical concept for Defining an acceptance conformity assessments based on interval smaller than probability theory and shows, how the tolerance interval, the risk of incorrect conformity the risk of wrong decisions by the assessment can be quantitatively producer is increased, calculated. In addition, it outlines whereby the consumer how these risks can be influenced risk is decreased through the introduction of guard bands and acceptance limits.

Tolerance and Acceptance Intervals incorrect decisions. Figure 2 shows Conversely, the producer has an A specific requirement typically an example of acceptance interval element of risk that an object takes the form of one or two shifting the risk to the producer: through the inspection process is tolerance limits that define an the acceptance interval is smaller incorrectly declared as a reject. interval of permissible values, called than the tolerance interval; a tolerance interval of a measurable hence fewer non-conforming In a conformity assessment, which property of the item (Figure 1). products will be put on the market. allows for only the acceptance or The guarded acceptance rule rejection of a product, the following An example of such a tolerance protects the consumer and four situations are possible (Figure 3): interval is given in the EU Regulation penalizes the producer. In the 874/2012 classifying lamps example mentioned above, the lamp a) Correct acceptance: The measured according to energy efficiency into producer could decide to declare a value is located within the different energy efficiency classes lamp to be class A if the measured acceptance region and the “true” (A++, A+, A, B, C, D, E). In order that energy efficiency index is larger than value is within the tolerance range. a non-directional lamp can be the AL = 0.19. He would therefore This is the desired result in the labeled as class A the energy reject lamp B even if there is 50% evaluation of a compliant efficiency index (kEEI) has to lie chance that the product complies. measurement between a lower limit TL = 0.17 and He therefore is accepting to reject b) False acceptance: The measured an upper limit TU = 0.24. If kEEI is more lamps than necessary. From a value is located within the outside these limits a lamp may not consumer point of view the risk of acceptance interval although the be labeled as A. Suppose that a buying a lamp wrongly labeled “true” value is outside the tolerance measurement of lamp A reveals a would be reduced in this case. range. The false acceptance is value of the energy efficiency index usually at the peril of the consumer and its expanded uncertainty of Choosing the tolerance limits or customer. Therefore this kEEI,A = (0.20 ± 0.02) and for a lamp and acceptance limits are business probability of false evaluation is

B of kEEI,B = (0.17 ± 0.02). In case A or policy decisions that depend referred to as consumer risk there is a good chance that the upon the consequences associated c) Correct rejection: The measured product is correctly labeled. However, with deviations from intended value is outside the acceptance in case B there is a probability of product quality. interval and the “true” value is out 50% that a wrong decision was made. of tolerance. This is the desired Both the producer and consumer result in the evaluation of a share the risk of a wrong decision. Risk Assessment non-compliant measurand The presence of a measurement d) False rejection: The measured By defining an acceptance interval uncertainty induces possible wrong value is outside the acceptance of permissible measured values of a decisions presenting a potential risk interval, although the “true” value is measurand, the risks of incorrect for consumer and producer. within the tolerance interval. The accept/reject decisions associated The consumer has a certain risk false rejection normally punishes with measurement uncertainty can that the object he gets does not the manufacturer or producer. be balanced in such a way as to conform, although it is rated at an Therefore this probability is referred minimize the costs associated with inspection process as compliant. to producer risk

Figure 3: Simple acceptance measured value is outside the decision rules near an acceptance region and non- upper tolerance limit conformity exists. From the two TU. Decisions to accept figures it is evident that the or reject inspected items are based on measured values that lie close to measured values the acceptable limit, have the (squares) in respect to highest specific risk. Assessing the the acceptance limit guard band and, thus the AU; the “true” values (disks) cannot be acceptance limits, affect the two known. Cases (b) and risks in a complementary manner: (d) lead to incorrect The consumer risk is reduced by decisions called false acceptance and false a greater guard band but at the rejection, respectively same time the producer risk increases. Conversely, the producer Figure 4: Illustration of specific risk is reduced with decreasing consumer risk for the guard band and consumer risk unilateral acceptance is increased. and tolerance limit Figure 4 illustrates the specific consumer risk for the unilateral acceptance and tolerance limit. The measured value y is within the acceptance and tolerance interval as the value is lower than the

acceptance limit AU and tolerance

limit TU. The risk that the actual value still lies outside the tolerance limit is given by the darker area of the distribution defined by the upper tolerance limit T . In this specific Figure 5: U Illustration of specific case, the ratio of the dark area to producer risk for the the total area of the distribution and unilateral acceptance thus the specific consumer risk and tolerance limit is about 4%.

Figure 5 illustrates the specific producer risk for the unilateral acceptance and tolerance limit. The measured value y is outside the acceptance but inside the tolerance interval as the value is higher than

the acceptance limit AU but lower

than tolerance limit TU. The risk that the actual value still lies inside the tolerance limit is given by the darker area of the distribution defined by

The terms consumer risk and than case d as the “true value” is the upper tolerance limit TU. In this producer risk are based on the idea outside the range defined by the specific case, the ratio of the dark that the conformity assessment is measurement value and its area to the total area of the part of a production process. uncertainty. distribution and thus the specific Knowing the measurement producer risk is about 85%. uncertainty of the measured A more detailed consideration is quantity the probability of a false based on the probability density decision made in b) and d) can be function g(η), which represents the Measurement Uncertainty calculated. In Figure 3 the upper uncertainty of the measured value y. Evaluation

limit of the acceptance interval AU is Figure 4 illustrates a compliant In order to be able to perform lower than the upper limit of the measurement with one-sided quantitative risk calculations it is

tolerance interval TU. Hence the acceptance and tolerance limits necessary to quantify the producer has a higher risk than the whereas figure 5 illustrates the uncertainty of the measurement consumer: case b is much less likely opposite case in which the process. For this purpose

international guidance documents the energy label of this specific lamp Global risks can be quantified as the exist: The Guide to the expression of is determined. The possibility of knowledge of the production uncertainty in measurement (GUM) misjudgment of this specific lamp is process that is characterized by a [2] gives the general concept. In the referred to as a specific risk. probability distribution similar to the field of photometry CIE has measuring process. With a means published the technical report CIE The global risk assesses the of probability theory the two 198:2011 Determination of average probability of misjudgments distributions (measuring process Measurement Uncertainties. based on a set of measurements. and prior knowledge about the These documents can be considered In contrast to the specific risk the possible values of the measured as the basis for all further CIE technical global risk is not based on the variable) can then be combined to reports and standards related to individual case, but takes into obtain a two-dimensional combined measurement. An example is the account all possible readings probability distribution of possible most recent standard related to LED defined within the context. As an values of the measured variable and measurements published by CIE. example, the global risk of wrong possible readings. For the decisions on the energy label assessment of global risk, this classification of a retrofit LED lamp two-dimensional distribution is Global Risk production line could be estimated evaluated. These calculations do not When assessing risks, a distinction as not each product will have the usually have analytical solutions and between specific risk and global risk same characteristics, but slight tabular values or numerical methods has to be made depending on the variations in the production are have to be used. One possibility information available. The specific possible. Knowing the production consists in the calculation of the risk assesses the probability of process allows restricting the set numerical simulation using computer misjudgments based on a concrete of possible measured values to software. The distributions are measurement on a specific item. calculate the average risk of represented by random numbers. As an example, the useful luminous misjudgments in general for the Using the random numbers, flux and the power consumption of a product. This is referred to as the production and the retro-fit LED lamp is measured and global risks. measurement process can be

simulated step by step. To according to its luminous flux. International LED determine the risks, only simple For a specific bin the lamp should Measurement arithmetic operations are then be within 950 lm and 1050 lm Standard CIE S025 necessary. Figure 6 a& b illustrate (tolerance interval). The production The International Commission on such numerical simulations, referred is optimized to 1000 lm but has a Illumination CIE published the first to as Monte Carlo simulations. spread of about 20 lm (standard internationally agreed measurement Each point corresponds to a certain deviation). For the measurement standard for LEDs: CIE S025 [4] “virtual” measurement value on a system, an expanded uncertainty of in March 2015. It provides “virtual” product. The figures can be 5% (k = 2) is assumed. In order to requirements to perform used to illustrate the global producer minimize the consumer risk to 0.1% reproducible photometric and and consumer risks: The blue boxes (hence 1 out of 1000 products on colorimetric measurements on LED on the left and right correspond to the market are wrong) the Monte lamps, LED modules, and LED the case where the measurement Carlo simulation (Figure 6 a) shows luminaires (LED devices) for values are within the acceptance that the acceptance interval has to operation with AC or DC supply limits but the product is actually be set from 980 lm to 1020 lm voltages. It also provides advice for outside the tolerance interval resulting in a producer risk of 53%: reporting the data. The standard (wrong acceptance and therefore Hence, more than half of the was developed by the technical consumer risk). The red boxes on products are rejected; resulting in committee CIE TC2-71 in close the top and the bottom correspond high cost. If the measurement collaboration with the European to the case where the measured capabilities are improved, Standardization Committee CEN values are outside the acceptance resulting in smaller uncertainties TC169 WG 7 (photometry). On the interval but the products would these costs can be reduced. European level, EN 13032-4 [5] is actually be within the specified Suppose that the measurement technically equivalent to CIE S025. tolerance interval (wrong rejection uncertainty is reduced to 3% and therefore producer risk). (Figure 6 b). In this case the The standard aims, in particular, to The risks are quantified by simply acceptance interval can be cover measurement methods for counting the points in the boxes in increased (965 lm to 1035 lm) in testing the compliance of LED respect to the total number of points order to keep the consumer risk devices with the photometric and on the graph. constant at 0.1% resulting in a colorimetric requirements of LED much lower producer risk of 15%. performance standards recently Hence reducing the measurement published by IEC [7, 8, 9]. Particular Reducing Production Costs uncertainty reduces the wrongly attention is given to the evaluation of by Improving Measurement decided rejects. The investment measurement uncertainty. Capabilities into more accurate measurement The measurement of photometric, The global risk is an important equipment, more characterization colorimetric and electrical quantities parameter when it comes to work including the evaluation of of an LED usually depends on many planning a measuring system for measurement uncertainty and more parameters, and an exact evaluation conformity assessment. careful measurements may, on a of measurement uncertainty is The following example illustrates the longer term, reduce the overall demanding and time-consuming. capacity of global risk assessment. costs of production and quality It is recognized that many different Suppose that a LED lamp is binned control. categories of laboratories use this

Figure 6: Risk assessment of the production of a 1000 lumen - lamp

standard, including manufacturers, Common to all measurements are In the annex of the standard, public testing laboratories, different examples for measurement R&D laboratories and National • Temperature setting and uncertainty evaluation are given. CIE Metrology Institutes. These uncertainty on temperature Division 2 is preparing a new laboratories have a wide range of measurement technical note [6] to give further levels of expertise in testing and in • Electrical settings and uncertainty guidance on the subject of the determination of uncertainties. In on electrical measurements measurement uncertainty. addition, a wide range of (power supply, electrical sophistication and accuracy of measuring instruments) equipment and quality of laboratory • Fluctuation of light output of the DUT Standard Test Conditions environment are used. The purpose • Calibration standard (calibration, for LED Measurements of this standard is that, by following ageing, calibration process, etc) CIE S025 requires that this test method, it is expected that • Linearity of measuring instruments measurements of the photometric, reasonable uncertainties of • Reproducibility and repeatability colorimetric and electrical measurements, as needed for (if applicable, default values for characteristics of a LED device shall various regulations and applications, the equipment and generic type be performed by means of may be achieved by most of the dependent figures may be used if appropriate equipment and laboratories. However, this test this is not evaluated for the procedures under defined standard method cannot cover all the details specific DUT) test conditions for operation of the of measurement instruments and device under test (DUT). CIE S025 possible mistakes that less In addition, contributions in specific uses the concept of conformity experienced laboratories can make. cases are given (i.e. flatness of assessment introduced above: mirrors in goniophotometers, spatial A standard test condition includes a The standard lists a large number of non-uniformity of sphere responsivity set value and a tolerance interval. possible contributions to the overall in sphere photometers, or stray light In addition, acceptance limits are uncertainty. of the spectroradiometer). defined for all parameters based on the measurement uncertainty.

As a general concept, the value and uncertainty of the measurement uncertainty while keeping the same its expanded uncertainty (k = 2, shall be considered. In practice it is consumer risk (Figure b) in respect 95% confidence interval) have to lie well possible to perform to figure a allows for increasing the within the tolerance interval. measurements of ambient acceptance interval and hence This corresponds to shifting the risk temperature with an uncertainty of reducing the production losses. to the producers. 0.2°C. In this case the acceptance interval of the ambient temperature An example: The set value of the measurement is ± 1°C. If the Conclusion rated supply current of the DUT ambient measurement has a larger Conformity assessment is a key (LED modules with DC current input) uncertainty (i.e. 0.5°C) the element in product testing and is 300 mA. The standard defines a acceptance interval will be reduced industrial quality control. In the tolerance interval of ±0,2% for DC to ± 0.7°C. Measurement presence of a measurement current (i.e. 0.6 mA). If the uncertainties are not directly uncertainty, the application of measurement of this current has an addressed within the IEC statistical methods result in the uncertainty of 0.2 mA the supply performance standards. quantification of potential risks for current measurement must be in the consumer and producer. In order to acceptance interval (300.0 ± 0.4) mA. Figure 6 shows the risk assessment be able to perform quantitative risk of the production of a 1000 lumen calculations it is necessary to In some cases the defined tolerance lamp. The specification limits are evaluate the uncertainty of the interval seems not to be in shown on the horizontal axis, the measurement process. In the field agreement with other international acceptance limits on the vertical of LED photometry the new standards. CIE S025 defines a axis. The producer risk is given by international measurement standard tolerance interval for ambient the relative number of points within CIE S025 gives clear guidance on temperature as ±1.2°C. In IEC the red boxes. The consumer risk the evaluation of measurement standard typically a tolerance of relates to the relative number of uncertainty. ±1°C is required. However CIE points within the blue boxes. requires that the measurement Reducing the measurement

References: [1] ISO/IEC Guide 98-4: 2012 - Uncertainty of measurement - Part 4: Role of measurement uncertainty in conformity assessment, also JCGM 106:2012 [2] ISO/IEC Guide 98-3:2008 - Uncertainty of measurement - Part 3: Guide to the expression of uncertainty in measurement (GUM:1995), also JCGM 100:2008 [3] CIE 198:2011 - Determination of Measurement Uncertainties in Photometry and its supplements [4] CIE S 025/E:2015 - Test Method for LED Lamps, LED Luminaires and LED Modules [5] EN 13032-4:2015 - Light and lighting - Measurement and presentation of photometric data of lamps and luminaires - Part 4: LED lamps, modules and luminaires (in press) [6] Technical note on the evaluation of measurement uncertainty for LED testing, (in preparation by CIE TC 2-71) [7] IEC 62717 ed1.0 (2014) - LED Modules for General Lighting - Performance requirements [8] IEC 62722-1 ed1.0 (2014) - Luminaire performance - Part 1: General requirements [9] IEC 62722-2-1 ed1.0 (2014) - Luminaire performance - Part 2-1: Particular requirements for LED luminaires

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TECHNOLOGIESCATEGORY CHIP ARRAY SMD LEDS 78 Chip Arrays in SMD Packages - A New Class of LEDs

Several companies have recently launched products that can commonly be referred as a new class of LEDs - Chip Arrays in SMD packages. These high-power LED packages can deliver between 300 and 1500 lm and are providing serious competition for Chip-on-Board arrays in this flux category. Ralph Bertram, System Expert at Osram Opto Semiconductors gives an overview of the benefits and drawbacks of these packages in LED retrofit lamps as well as in different types of luminaires. Case studies illustrate the huge benefits that CAS can generate when used in spotlights and in omnidirectional light sources. It also addresses lifetime and reliability concerns and shows how the right choice of products and good thermal design can satisfy even high demands.

The recently launched Chip Arrays All Chip Array LEDs in SMD of CAS LEDs is generated by in SMD packages (CAS) combine packages available on the an array of volume-emitting the high efficacy and light market feature a luminous flux (“Sapphire”) LED chips. output of CoB LEDs with cost- of more than 300 lm - but some However, the CAS chips are effective and reliable assembly can even deliver in excess of mounted on a highly reflective using Pick&Place electronics. 1200 lm. Because of these leadframe material or even on a The PCB (Printed Circuit Board) high flux levels, retrofits with ceramic substrate. All of these is no longer part of the CoB equivalent wattages of 25 to chips emit blue light and are but part of the luminaire again, 75 W are feasible with only one embedded in a phosphor-filled so there is greater freedom of LED package. Leading lighting silicone material that generates design for manufacturers. manufacturers have tailored white light. Therefore, simply This opens up additional their products exactly to the by exchanging the reflective possibilities for including lumen packages needed for PCB material with a leadframe, features such as thermal fuses, directional and omnidirectional manufacturers can ensure connectors or even driver retrofits, ensuring sufficient easy SMD assembly without components directly on the LED efficacy to reach EU Energy compromising the efficacy or board. Thanks to these interesting class A+. Common package other positive properties of CoB features, high-power LED form factors include dimensions LEDs. Table 1 compares lumen packages are providing serious of 5 x 5 mm, 7 x 7 mm and even packages, system costs and competition for Chip-on-Board 9.5 x 9.5 mm. As in the case of other characteristics of different arrays in this flux category. Chip-on-Board LEDs, the light types of LED.

Table 1: CAS leadframe- CAS ceramic 3030 leadframe- Comparison of different CoB Ceramic HP-LED LEDs with regard based package package based package to lumen packages, lm/package 300-10,000 lm 300-1200 lm ~400-1600 lm ~110 lm 100-1200 lm efficacy, system costs and reliability Efficacy ++ + + + ++

High- Cost-efficient, Easy manual Cost-efficient, temperature Greatest Features but multi-spot assembly SMT assembly operation robustness appearance possible

Relatively high Savings through Savings through Commodity LED costs for a LED price, Higher LED System costs system and product with small lumen system and costs assembly costs lowest price package assembly costs

Reliability Basic Basic Good Basic Excellent

Figure 2: Many Benefits, Several Thermal simulation for Challenging Drawbacks a Duris S10 CAS device The first generation of CAS LEDs on a hot plate was designed for use in retrofits, especially for directional MR and PAR lamps. Therefore, the lumen packages of these first products were optimally adjusted to replace halogen lamps with 20 to 50 W. Accordingly, they were used as single light sources without providing multiple spots or multiple shadows. Consequently, they satisfied the wishes of many customers who wanted to achieve the same look and feel with the new LEDs as with the halogen lamps they had been using before. Until then, this had only been possible with CoB LEDs. They need impacts on a CAS package is in the Like CoB LEDs, Chip Array SMD hand-soldering or you manually range of several watts. We should packages of the first generation have to insert the parts into holders. therefore take a close look at the featured a circular light-emitting Meanwhile, the first manufacturers thermal properties of these surface (LES) so there was little realized that this package type products: Most CAS LEDs are concern in terms of optics design. could also be used for higher leadframe-based, so the LED chips For a 5050 device the typical wattages, enabling only one LED to are placed directly on the copper- diameter is 4.6 mm, emitting 300 be incorporated in omnidirectional based leadframe. The thermal to 500 lm. However, since the retrofits. In this application, the other resistance of the package itself packages are square by nature it benefits of CAS LEDs come into (from junction to solder point) is was discovered that efficacy can play. Thanks to their SMD packages, excellent and even better than that be significantly increased if the automated assembly is possible and of CoB products (e.g. 1.2 K/W for a light-emitting surface is also square. the use of connectors or even driver 10 W device). However, unlike in This results in an increase in the components on the LED PCB can CoB products the heat is not yet in effective diameter up to 5.7 mm. pave the way for full automation of the metal core of the PCB, it still has This is usually not very significant retrofit production. These characteristics to cross the dielectric. Therefore, but it does have an impact on of retrofits also can be applied to the additional thermal resistance of optics design. Compared to CoB luminaires. With cost-efficient the dielectric has to be included. LEDs in the same power class, Chip Array SMD LEDs, a large Of course, this depends on the the diameter of the CAS LES is variety of luminaires, including material used for the PCB. For an still small (6 to 10 mm). downlights, tracklights and average-performance PCB the value spotlights, can be produced is around 1.3 K/W, making the total Another important aspect to without compromising appearance. thermal resistance slightly higher consider is color consistency: than that of a CoB. By using proper Since the CAS will probably function PCB design there should be no as the only light source in an end need for additional electrical product; color binning has to be isolation against the heat sink. carried out carefully to avoid In this case, the PCB should easily unpleasant color variations from withstand several thousand volts as lamp to lamp when mounted in the required during certification testing same installation. Unfortunately, according to IEC 61347 or UL 1310. because of the production For the 10 W device mentioned processes involved, no above, our thermal simulations manufacturer can yet achieve a Figure 1: The new Duris S 10 from is an example of a CAS LED have shown a rise in the typical distribution below 3 MacAdam junction temperature against a steps, as is standard in CoBs. heat sink of 29 K, compared to A proper assessment should be Despite all these benefits, there are 21 K for a CoB (Figure 2). conducted to see whether a larger also a few things that have to be color variation can be accepted in considered when designing with With regard to the optics and a project or tighter bins need to be CAS LEDs. Owing to their higher color of CAS LEDs, a few interesting purchased at extra price. luminous flux, the thermal load that aspects have come to light.

Figure 3: LM-80 data (lifetime) One of the main concerns with the of the first generation new package class is robustness. of the Osram Duris Is it good enough for the intended S8. Tests with the applications? Since most of the second generation with improved design are designs available on the market currently ongoing contain the soft metal silver in their leadframe material and plastics as their housing material, these concerns have to be taken seriously. Below we take a look at the different materials in the CAS package.

Chips and phosphor The volume-emitting chips as well as the phosphor-filled silicone resins Figure 4: that are responsible for light First solder joint failures detectable by conversion are the same as used in a sudden increase in other LED types. So no reduced - forward voltage. The or improved - performance is to number of temperature be expected here. cycles is dependent on the difference in temperature Leadframe The leadframe is both the supporting mechanical structure and the thermal and electrical contact to the board. As in CoBs, the leadframe of CAS LEDs also serves as a mirror to help emit the light from the package. It therefore needs to have excellent reflectivity properties and it should typically be silver-coated. So the presence of corrosive (especially sulfuric) gases leads to accelerated exposed to light can be minimized in case by case based on system aging that reduces the brightness relation to the mirror or leadframe comparisons as to which material of the chips. If CoBs or CAS LEDs surface, package aging can be is the best for achieving the values are used in harsh environments reduced to a minimum. If the latest of efficacy, costs and lifetime proper shielding against such generation of epoxy-based material intended for the product. substances is recommended. is used, the packages can exhibit LM-80-lifetimes that are sufficient In consumer retrofit applications for most applications (Figure 3). lighting solutions such as lamps or Housing material luminaires need to withstand several Most of the concerns with mid- on-off cycles per day. This is why power LEDs and with Chip Array Choosing the Right CAS temperature cycle stability is critical in SMD LEDs relate to the aging Design for an Application these applications. As the difference of plastic materials at high As mentioned above, customers can in thermal expansion between the temperatures and intense light choose between leadframe-based copper leadframe and the aluminum levels. Indeed, the early and ceramics-based CAS LEDs. By core of the board is minimal, it is polyphthalamide (PPA) packages using ceramics, the thermal advisable to use leadframe-based were mostly limited by this effect. resistance of the package will be CAS LEDs for applications in which Nevertheless, a proper design will greater than with a copper frequent and/or high temperature limit the exposure of the package leadframe. However, because of the cycles are expected. The strain on the material to blue light. Even this inherently better robustness of this solder joints is greater as the device material can exhibit long lifetimes as package type higher driving gets larger. Figure 4 shows how many recently demonstrated in a tunnel temperatures are also possible - cycles have to take place until project in Shanghai [1]. Since in at the expense of some efficacy. detectable failures in solder joints large packages the plastic surface A decision should therefore be taken occur, as a function of the difference

in temperature. In this graph there Overall, the number of chips are data points for a 3030 in a CAS is similar to existing aluminum nitride ceramic package designs, so the forward voltage as well as calculations according and power requirements are to the Coffin-Manson model for a compatible with existing drivers. 30-minute temperature cycle. Quite a variety of CAS LEDs is available in different power classes so all typical retrofit Practical Test: lumen packages can be easily CAS LEDs Used in achieved. But there is an Lighting Solutions additional factor often Both omnidirectional and overlooked in retrofit designs. directional retrofits can benefit When it comes to mass from the use of Chip Array production, the assembly SMD LEDs. costs are a significant part of the total product costs. In A-lamps and candelabra-type So automated assembly should lamps, CAS LEDs can replace a be used wherever possible. number of smaller mid-power Today, more and more retrofits LEDs at a comparable price. are designed with SMD This enables the use of “virtual- connectors on the LED board filament” optics in a larger range that add little to the bill of of power classes than at present. materials, but result in considerable savings and In MR 16-type retrofits, CAS LEDs additional reliability on the offer a cost-effective solution for assembly side. This is the main single-source halogen look-alike reason why it is highly likely that lamps, removing the infamous SMD components will ultimately “multi-shadow” effect. However, prevail over semi-automated the design of the optics here is assembly of CoB LEDs in all challenging. According to the high-volume applications. basic rules of optics, the size of a lens on a larger source has to be proportionally greater than for CAS LEDs in a smaller source. As you only Professional Downlights need one instead of three or four Professional (6-inch to 8-inch) lenses, the diameter of the optics downlights used in office can be comparable (Figure 5). buildings and shops are often On the other hand, the lens is based on Chip-on-board LEDs higher, requiring an additional because a single light source in amount of precious space inside the center of the luminaire offers the MR 16 shape. a certain degree of lighting

Figure 5: One CAS LED can replace three or four smaller LEDs in an MR16 lamp

control. And it provides the look be produced with 5050 CAS LEDs Conclusion and feel of a halogen or HID bulb or CoBs with an LES of 14.5 mm. A detailed study shows that CAS LEDs that has been missing in compact- The space between the single LEDs have a few drawbacks that need to be fluorescent-based downlights is so small that there is virtually no taken into consideration, such as the over the last few decades. difference to a “real” CoB. additional thermal resistance, depending on the material used for the pcb, or However, the brightness levels of However, real advantages can color binning that has to be carried out 2000 to 3000 lm are still too high to be achieved when the PCB is carefully to avoid unpleasant color be achieved by a single CAS LED. used for more than just providing variations from lamp to lamp. However, So how can system costs be a thermal interface. For example there are more benefits of this new reduced here? The answer is thermal fuses or even parts of the type of LEDs, notably the smaller LES a cluster of CAS LEDs. The size driver or the control electronics and the considerable cost advantage of a 2 x 2 array of 7070 LEDs is can be included on the LED pcb. compared to CoBs. But the main still smaller than a CoB with an Mounting holes can be placed reason for using CAS LEDs is probably LES of 22 mm (diameter). where the manufacturer needs the easier assembly that will ultimately After adoption of the PCB layout them and not where the CoB prevail over semi-automated assembly the CoB previously used can manufacturer placed them. of CoB LEDs in all high-volume simply be replaced without any Affordable poke-in connectors applications. Until then, manufacturers other changes to fixture design. are also available that can be have to know the trade-offs in thermal This leads to even more light assembled directly together with performance, lifetime and color output or greater efficacy the LEDs so there is no further consistency and can easily choose the compared to CoBs. need for manual soldering or type of LED that is perfect for their Similar designs can fiddly holders. lighting application.

References: [1] Alexander Wilm, Osram Opto Semiconductors, “LED Tunnel Lamp - A Reality Check: 50,000 Hours Field Data and Lifetime”, LED professional Symposium 2015, Bregenz

TECHNOLOGIES PCB DESIGN & LAMINATE SELECTION 84 Mastering Thermal Issues in LED PCB Design & Laminate Selection

LED applications are not the only applications that are driving the need for thermal issues to be considered and mastered in PCB design, but they are certainly amongst the most challenging. Designing LED PCBs requires many considerations and key are those that arise from multiple heat sources in close proximity. Martin Cotton, Director OEM Technology of Ventec Europe describes the process and criteria used when designing PCBs (Printed Circuit Boards) for use in LED applications using thermally conductive IMS (Insulated Metal Substrates). He goes into technical detail with charts and diagrams that explain everything the designer would need to consider when selecting a laminate and commencing a design.

A PCB design for LED lighting vendor are considered to Introduction products belongs to the most create workable design rules Various methods have been challenging tasks, a proper that include coin cavity and considered, tested and used in the process and criteria is very adjacency dimensions. dissipation of heat from the PCB helpful when designing PCBs It looks at options for thermally and from the devices on the PCB. (Printed Circuit Boards) for conductive laminates; glass The most obvious and perhaps the use in these applications using reinforced thermally conductive traditional solution is the heatsink - thermally conductive IMS prepregs, thermally conductive a piece of metal with a large surface (Insulated Metal Substrates). dielectrics and IMS (Insulated area provide space for the heat to Therefore, the requirements Metal Substrates) materials. flow into the air having been swiftly for thermal management and and efficiently removed by the various issues that form A focus is on the make-up of conduction from the device or heat the development of design these IMS in the form of copper- source. As well as device mounted rules and build structure for laminate-aluminum or copper- heatsinks, PCB mounted heatsinks the Printed Circuit Board laminate-copper, considering are often used to connect the heat will be outlined in the article. the various characteristics, source to as large an area of Furthermore, the manufacturers benefits and the thermal conductive material as possible, specification and those conductivity and impedance often covering the entire unoccupied provided by the laminate of each option. surface area of the PCB.

Figure 1: The images below show the thermal impact of LEDs and of other devices such as processors

Figure 2: Various methods are used during the PCB fabrication process to provide heat dissipation via areas of copper called coins

Figure 3: Coin dimensions & tolerances

More recently, laminate technology As can be seen in figure 3, the size hardware designer who should has come to the fore and the use of of the coins is critical along with its provide detail on the devices used in-PCB heatsinks, such as coins, proximity to other PCB features and their thermal characteristics. has become more prominent with such as through-holes and inner This data, combined with that from large areas of copper being used layer traces and other components the PCB manufacturer and the as “heatdumps” to deposit and on the PCB. These dimensions laminate supplier, will ensure the dissipate thermal energy. These are will differ when the board is correct choice of materials is made sometimes within a space milled conventional PTH (Plated Through- and the process tolerances are into the PCB surface, but can even Hole) as compared to boards that applied along with the dimensional be on inner layers and sometimes use micro-via technology. demands from the thermal on multiple layers connected by requirements and challenges. through-hole plating. In simple For this reason early consideration These dimensions and tolerances terms a coin is a thermal heatsink of the heat dissipation requirements are then applied to any drawings within a PCB. are essential. Creating design rules required by manufacturing to that apply to the coin cavity should produce the product and shared It is tempting to take a very industrial be done at the same stage as the and approved by the various approach to heatsinking, placing a specification of the laminate and the stakeholders to ensure all parties heatsink as large as you can fit on other design rules around layer have an input into the most the offending device. This is a count, track and space, etc. desirable, effective and economic somewhat unscientific approach choice of heat dissipation, and may result in shifting the Design rules are required and start laminate selection and problem elsewhere as well as being with what a designer wishes to fabrication methodology. more costly than the designed and produce. They are conjoint feedback calculated solution. from manufacturing and design on Design rules are created not only what minimum or maximum for what we are currently able to dimensions apply, plus the produce, but also to push the Designing with Coins tolerances associated with boundaries of what we might need The coin cavity cross section design those manufacturing processes. to build in the future. This drives the is critical and minimum clearance as The designer will be pulling technology roadmaps of the parties well as maximum and minimum together data from a broad team involved, largely the fabricator and tolerances are generically required. of participants starting with the laminate manufacturer.

Table 1: A typical set of coin component and the impact in design rules and the X, Y & Z axis needs to be associate dimensions considered in detail.

Each coin cannot be treated in isolation. They all impact upon each other and proximity is critical, as is the differing heat load of each coin. High load coins will need to be separated from each other, sometimes by laminate and other times by low load coins.

Replacing Coins with “Local” Heatsinks Using IMS Materials Thermally Conductive IMS PCBs offer various solutions, with various component parts. These include:

• Thermally conductive laminates • Glass reinforced (VT-4Ax) thermally conductive prepregs, unsupported (VT-4Bx) thermally conductive dielectrics • Insulated metal substrate (IMS) materials

As an alternative or replacement to coins, this provides the ability Figure 4: Heatsinks could to manufacture or fabricate local become connector heatsinks on the PCB. routes as well as thermal coins Coining and local heatsinks are very specific solutions, aimed at prime components and focused at a component level. IMS is broader and is less focused, but perhaps needs a better and more detailed design strategy, particularly if you want to move it away from a specific PCB by PCB solution or technology level to a more generic solution. Certainly the LED industry is asking a lot of questions and making great demands for better thermal management. The PCB fabrication Development programs come out Consideration needs to be given industry and the laminate producers from these “design” requirements, to the laminate thickness when need to work in concert with the and they should. As laminate specifying the minimum distance PCB and hardware design producers we want to make between coins. Coins can be of community to ensure they specify products that meet and surpass varying thicknesses and can also and create the best solutions. current and future demand. be on the same or the opposite We should avoiding developing sides of the PCB. These all have As part of the design process it technology because we can, different thermal impacts as well is essential to create a test process and focus on developing what we, as dielectric considerations, that considers all the elements our customers, and our customers’ while some strategies may impact in creating a workable solution. customers need. on potential delamination. It is easy to study the data sheets The PCB is a three dimensional and compare materials that way,

TECHNOLOGIES PCB DESIGN & LAMINATE SELECTION 88

Figure 5: Examples of data sheets but each project needs to be be able to walk you through the an expensive and lazy solution, carefully considered, as many selection criteria for their materials. which will doubtless be costly. factors impact upon the final Some vendors will have elements of selection of material. design expertise within their team, Another environmental factor is the but some may not. Working with a surrounding product and the impact Many experienced designers and vendor with a sound understanding that it has on thermal management. engineers will say that whilst the of the design principals is very If the product dissipates heat in a data sheet is the ideal starting point, important if you are to use the right way that negatively impacts on other it does not provide the whole material rather than one which will products, that will automatically answer. This is not because vendors work because it is vastly over- create and problem. Conversely set out to produce misleading data, specified for the task at hand other products or devices in close it is because data sheets are based and hence too expensive. proximity will impact the thermal on tests performed by the vendor in performance of the design. a certain environment and in certain When doing the thermal calculation circumstances that will inevitably be it is also essential to consider the Also important in material selection different from your derived data. thermal configuration and not just are mechanical properties and the resistance or conductivity, mechanical stresses that the Studying the data sheets requires but also the thermal impedance, product may be under in the field. the consideration of many elements, which many consider a more not least the material build. consistent and accurate measurement. Manufacturing processes have Also important to consider are the to be considered and the fabricator thermal conductivity of the various One influencing factor is and assembler will each have their materials as well as the thickness environmental. Where will the input into the best solution. In this of the copper, the dielectric and PCB operate? Will it be potted? process you will also need to the aluminum and aluminum alloy. Will the flow of air around it change consider compliance to agency in different applications and will it or customer approvals. Reaching out and building a close deteriorate over time? A key factor relationship with the technical team in selection is reliability, but just at the laminate vendor will be very building in the maximum reliability Conclusion valuable at this point. They should and maximum heat dissipation is At the end of the day the solution needs to suit the product and be Figure 6: Thermal system cost effective, not belt and braces configuration because we don’t understand the parameters at play. Short cuts will result in one of two outcomes: A product that isn’t fit for purpose; or a product that is so over- engineered that it fails to be a cost effective solution.

ZHAGACATEGORY SPECIAL OVERVIEW 90

ZHAGA SPECIAL: NEW BOOKS 2015 - TECHNICAL PAPERS

91 Zhaga Evolves: Focus on Component Standardization Drives New Book Development by Musa Unmehopa & Tim Whitaker, Zhaga Consortium

96 Chip-on-Board LED Modules Standardized in Zhaga Book 12 by Martin Creusen & Charles Knibbeler, Philips Lighting; Manfred Scheubeck, Osram Opto Semiconductors; Ingo Arnrich, BJB; Nico van Stiphout, Molex

100 Light-Emitting Surface (LES) Concept Enables Comparison of Photometric Properties by Stefan Lorenz, Osram GmbH

104 Zhaga Determines Thermal Fit of LED Light Engines and Luminaires by Uli Mathis, Tridonic; Toine Staring, Philips Lighting

106 DMI Specification Defines Electrical Interface between LED Drivers and Modules by Arnulf Rupp, Osram

With new specifications covering COB LED arrays, LED drivers, and other LED modules and light engines, Zhaga is making rapid progress in standardizing these types of components in response to the needs of the market. Musa Unmehopa, Secretary General of the Zhaga Consortium, and Tim Whitaker, Director of Marketing Communications of the Zhaga Consortium, describe how Zhaga is evolving and changing its focus in a number of areas.

In the five years since its Meeting the Needs including both circular and linear inception, the international of the Market light sources. One new specification, Zhaga Consortium has made Zhaga is currently going through a Book 14, will describe linear rapid progress towards its period of evolution, reflecting the modules with cap-holder systems central goal of standardizing a changing demands of the global that enable end-user replacement. broad range of LED modules, lighting marketplace. One major Other proposals include both LED light engines and related change for Zhaga is the creation driver-integrated LED light engines, components. of separate specifications for as well as LED modules with LED modules and LED drivers separate drivers. The Zhaga specifications, (also referred to as electronic control known as Books, remove gear). This approach will enable Zhaga has also undergone an arbitrary and unnecessary luminaire makers to use different exercise to ensure that its variations in various properties, combinations of LED modules and specifications only cover the such as physical dimensions, drivers, according to their own properties necessary to enable making it easier for luminaire unique requirements. Of course, interchangeability, while at the makers to base their designs on this also requires that the electrical same time, allowing unrestricted interchangeable components interface between modules and possibilities for other aspects of that are available from multiple drivers is defined correctly. component design. different suppliers. One consequence of this work is the creation of a new specification, Products based on several of entitled Book 13, which focuses Separate Books for the Zhaga Books are already entirely on LED drivers. Modules and Drivers in common use in the global As stated above, Zhaga is now lighting market. Form-factors Zhaga has also made rapid progress writing separate Books for LED standardized by Zhaga, such in defining a new specification that modules and LED drivers. as linear Book 7 modules or covers chip-on-board (COB) LED Previously, all Zhaga Books defined circular Book 3 modules, can be arrays, in response to requests from a complete LED light engine (LLE). found in the portfolios of many many key stakeholders in the Zhaga defines an LLE as a leading lighting-component industry. As discussed below, the combination of one or more LED suppliers around the world. forthcoming Zhaga Book 12 will modules and a suitable driver, Meanwhile, Zhaga continues to include a family of different COB where the driver can be either develop new specifications that module sizes. separate from the LED module(s), reflect the needs of luminaire or integrated inside the LLE. makers and other stakeholders. Other new Books are also being For LLEs with an integrated driver, developed by Zhaga to meet the Zhaga Books will continue to requirements of the lighting industry, define the complete LLE.

Figure 1: For LED modules that are powered by a separate LED driver, Zhaga is writing individual Books for different LED module types. Meanwhile, a broad range of LED driver types are described in Book 13, some of which can be used in multiple applications to supply power to different LED module types

Figure 2: This schematic diagram gives an example of some of the interfaces However, for all LLEs where the defined by Zhaga for an LED module with driver and module(s) are separate, separate driver. individual Books will be written The dashed boundary that cover each different LED lines show which module type or family (Figure 1). interfaces are included in the module The corresponding drivers will and driver Books, be described in a single new respectively. In this specification, Book 13. This change example, the LED will be applied retrospectively to module Book defines the thermal and existing Books with separate mechanical interfaces modules and drivers. with the luminaire’s heat sink, the photometric interface of the module Interfaces the LLE and the luminaire. Now that makers and other stakeholders to with the luminaire’s The Zhaga Books are interface separate Books are being written compare the properties of different optics, and also specifications, and each defines an for LED modules and drivers, LED drivers. For example, a luminaire the mechanical and electrical interfaces LLE and/or associated components this changes the specific interfaces maker may wish to determine which with the driver (including LED modules and drivers) that are included in each Book. drivers are compatible with different by means of the mechanical, Figure 2 shows a schematic image LED modules, and whether a driver photometric, electrical, thermal, of an LED luminaire containing a will fit inside a given luminaire. and control interfaces of the separate LED module and driver. product to its environment. The dashed boundary lines show Two crucial aspects that determine if In many cases, the “environment” which interfaces are included in different drivers are interchangeable is an LED luminaire. either the module Book or the are the mechanical and electrical driver Book. Note that the scenario interfaces between the driver and By specifying interfaces, this makes shown in figure 2 can vary from module. The electrical interface is such LLEs or components Book to Book. discussed in the next section of interchangeable in the sense that this article. it is easy to replace one LLE or component with another, even if Book 13 Defines To enable the physical interchangeability they have been made by different LED Drivers of drivers in a luminaire, the mechanical manufacturers. A typical LED driver can be used in dimensions must be clearly specified. multiple applications to supply To serve all applications, Zhaga Previously, when Zhaga Books power to different LED module types. Book 13 defines a range of driver defined complete LLEs, all the The purpose of the Book 13 form-factors. In addition to specified interfaces were between specification is to help luminaire the maximum outer dimensions

(demarcation) of the driver, having to use a different LED driver products from different suppliers each form-factor is characterized for each module, or vice versa. without changing their luminaire or by both the position and number Zhaga refers to this as “independent holder designs. of mounting holes, and the position (or component) interchangeability” of the electrical wiring to the of LED drivers and modules. In consultation with many interested LED module and to the mains parties, Zhaga was asked to power source. With separate specifications for LED standardize properties such as the modules and LED drivers, this also mechanical dimensions of the In total, across all form-factors, requires that the electrical interface module, the position of electrodes, Book 13 includes 78 drivers with between modules and drivers is and the diameter of the light- different dimensions. Two categories, defined correctly. emitting surface (LES). The results designated Types A and B, of Zhaga’s work can be found in have been developed by Zhaga. To avoid duplicated efforts in the the first edition of Book 12, With a total of 27 different driver industry, Zhaga decided not to write its specification describing LED dimensions, Types A and B can a new specification for this driver- modules that typically use serve nearly all applications, both for module interface (DMI). Instead, COB technology. compact luminaires (Type A - 13 Book 13 references a specification different size categories) and for written by MD-SIG. This is an The specification defines a family of areal lighting (Type B - 14 different external industry association which six rectangular or square modules sizes) over a very wide range of is not part of Zhaga, but in which with a circular LES. The modules output powers. Zhaga recommends several Zhaga members participate. have the following dimensions: that the new form-factors in Types A 12 x 15 mm, 16 x 19 mm, 19 x 19 mm, and B should be adopted for new The DMI comprises two separate 20 x 24 mm, 24 x 24 mm, and luminaire and driver designs. parts; the information interface and 28 x 28 mm. Further details about the power interface. Further Zhaga’s efforts to standardize COB However, the consortium also information on the DMI and MD-SIG LED arrays are documented in the acknowledges that there are many can be found in the article beginning article beginning on page 96. existing driver products in the market, on page 106. and these will require a long, gradual phase-out period. For this reason, a Choosing the Right broad range of additional driver Zhaga Standardizes Parameters designations (types 1-8) are also COB Arrays Another recent activity by Zhaga included in Book 13. COB arrays are already in members was to undertake a widespread use throughout the LED comprehensive review of the lighting industry, but different parameters included in each of its Component manufacturers offer a wide range of specifications. The goal was to Interchangeability and DMI alternative sizes. For luminaire ensure that the full parameter set The new Book 13 is part of Zhaga’s makers and other stakeholders such of each Book includes all the efforts to enable LED luminaire as suppliers of optics and COB characteristics necessary to enable manufacturers to use different LED holders, this creates problems and interchangeability of LLEs, drivers, modules in their luminaires without limits their options to use alternative modules and other components.

Table 1: Parameter or Not Specified by Comparison of Property Type Zhaga Restricted Listed on Product Datasheet parameter types for LED modules and Value is not restricted. Requirement for their relationship with No requirement Little or no variation is permitted Value must be shown on product Zhaga Compliance Zhaga specifications. datasheet Zhaga only restricts a small number Not relevant, or data Relevance to Values required to enable available from other Essential of parameters, Interchangeability comparison of products sources enabling maximum design freedom. Implications for The parameters that Full design freedom Limited or no design freedom Full design freedom Design Freedom are required on datasheets allow Test lab compares measured meaningful comparison Implications for values with manufacturer’s of products Not tested Fully tested to ensure compliance Zhaga Testing datasheet. Some parameters not tested

Screw-hole size and position; Efficacy (lm/W), max. outer dimensions of LED Luminous flux, maximum Examples choice of materials module and corresponding operating temperature demarcation area in luminaire

The starting point was to create an freedom by only restricting those consumer sector. Book 9 LLEs exhaustive list of properties parameters that are essential to comprise a non-socketable LED associated with the components ensure interchangeability. module with a ring-shaped light- described in each Zhaga Book. emitting surface (LES) and a A number of luminaire makers and separate LED driver (Figure 3). other stakeholders were asked to Certified Products The LED modules are small in size - explain their requirements and Products that have been tested the LES diameters are 12 mm or preferences for each of the by an independent testing lab, 25 mm - with simple construction properties, in order to determine and are fully compliant with all the and a low profile (4 mm height). which properties should be requirements of one of the Zhaga The light output is typically in included in each Book. Books, are allowed to carry the the order of several hundred to Zhaga logo. This symbol conveys around one thousand lumens. The characteristic properties of the assurance of interchangeability, These features mean that Book 9 the LED light sources were assigned but also means that the product is LED light engines are highly suited to one of three groups (Table 1). traceable through Zhaga’s online for use in LED luminaires for The first group includes properties Certified Products Database [1]. consumer lighting applications, that are not relevant to such as small spotlights, track interchangeability, or are readily The database has been updated lighting and other compact available elsewhere, and are recently, and now has a very luminaires. However, Zhaga does therefore not included in the comprehensive search functionality. not restrict the applications that Zhaga specifications. This allows potential purchasers can be addressed. to compare products, based not The second group of properties only on which Book the product includes those that are considered belongs to, but also by looking at Books 3, 10 and 11 essential to interchangeability, various key properties. For example, Zhaga is building on the success and are restricted by the Zhaga when selecting a Book 3 LED of Book 3, which defines specifications, such that little or no module, the user can not only 50-mm-diameter modules for variation is allowed. Many properties choose the desired LES category, spotlighting and related applications. in this group relate to the but can also compare luminous flux, The range of spotlight modules mechanical fit. color-rendering index, correlated is being extended to both larger color temperature and other (75 mm diameter) and smaller The third group contains parameters properties. (35 mm diameter) sizes, which are where the value must be known in designated Book 10 and Book 11, order for a customer to determine if respectively. Book 11 was published one light source is interchangeable New Books and by Zhaga in July 2015. In fact, with another. However, Zhaga does Extended Families due to the similarities in these not restrict the actual values of modules, Zhaga has already these properties. One example is Book 9 decided to merge these Books luminous flux. Typically, for each Zhaga extended its library of into a single specification. Book, Zhaga will define a set of specifications in June 2015 with categories based on luminous flux the publication of Book 9. ranges. A product can have any Compared with earlier Books, Book 7 value of luminous flux, but the flux which are aimed at professional LED modules using the form-factors range must be stated on the lighting applications, Book 9 in Zhaga Book 7 are now a common datasheet. This enables a customer represents a shift towards the sight in the market. Included in looking for closely-matched Figure 3: There are two interchangeable products to select categories of Book 9 from alternatives that are in the modules (left). These same flux category. have a ring-shaped light-emitting surface with a diameter of Because Zhaga requires LLE either 12 mm or 25 mm. manufacturers to provide a detailed Book 11 modules set of parameters for each product, (right) have an overall this allows luminaire makers to diameter of 35 mm, compared with 50 mm make meaningful comparisons and for Book 3 modules informed choices based on dependable data. However, it is important to note that many properties are not restricted by Zhaga. This promotes design

Book 7 is a scaled family of linear New Proposals Conclusions modules, with lengths of 280 or Zhaga is now reviewing a series By listening to feedback from 560 mm and widths of 20, 40 or of new proposals from its member stakeholders, and responding 60 mm. Recently, two additional companies: in a timely and efficient manner, square modules with sides of the Zhaga Consortium is continuing 380 and 560 mm have been added • Planar, large-diameter, circular to provide an important contribution to Book 7. Such modules are suited LLEs (with integrated driver) for to the ongoing growth and for indoor lighting applications potential use in flat, circular development of the LED lighting such as office lighting. luminaires with a homogeneous, industry. Changes have been put in low-glare surface place that will enable component • Rectangular LED modules interchangeability of LED modules Book 14 (with separate driver) for use in and drivers, as requested by the The latest proposal to reach the combination with lens plates, market. Zhaga is also expanding its Book-writing phase is Book 14, in outdoor lighting applications portfolio of specifications for LLEs, which will define specifications for • Circular, small-diameter, spotlight- modules and drivers, and is building linear, socketable (tool-less type LLEs (with integrated driver) scaled families of interchangeable replaceable) light engines and for use in applications such as products that provide choice for modules with a cap-holder fit system. compact spot-type indoor luminaire makers alongside the luminaires (e.g. track lights) benefits of standardization. The Book will include versions with integrated drivers and versions with These proposals were made after separate drivers. Three length Zhaga identified opportunities and designations (lengths of approx. set priorities for new specifications 1400 mm, 1120 mm and 560 mm) that will provide most benefit to the are likely to be included. LED lighting industry.

References: [1] Zhaga online Certified Products Database : www.zhagastandard.org/products/certified

In order to address the complexity of dealing with a wide range of Chip-on-board (COB) LED modules, the Zhaga Consortium has standardized a family of form-factors in its new specification, Book 12. Martin Creusen and Charles Knibbeler from Philips Lighting, Manfred Scheubeck from OSRAM Opto Semiconductors, Ingo Arnrich from BJB and Nico van Stiphout from Molex discuss the numerous issues that have been addressed by Zhaga, leading to a mechanical interface specification for these components.

Figure 1: Zhaga Book 12 Chip-on-board (COB) [i] specifies a family of LED arrays are already in square and rectangular widespread use throughout LED modules with a the LED lighting industry, circular light-emitting surface (LES). Typically serving a broad range of indoor these modules use and outdoor applications. To chip-on-board (COB) address this market, many technology, but this is alternative COB form-factors not mandatory have been developed and are being supplied by multiple COB manufacturers. However, most of these form-factors offer only arbitrary variations in non- competitive properties such as outer dimensions and electrode positions. This increases the complexity of luminaire development and of the supply chain for lighting OEMs. COB Form-Factors a 4 mm interval between 12 and Many Zhaga members were 28 mm, to attain five evenly-spread As a result, stakeholders such concerned about this growing COB categories of rectangular and as suppliers of COB holders or redundant diversity. Consequently, square COB modules. optics have to accommodate they initiated a standardization numerous slightly different request and started a so-called To ensure the future robustness of solutions to supplement this Zhaga taskforce. The first task was the upcoming Zhaga COB complex COB portfolio. In to analyze and make an inventory of specification, a rectangular shape addition, for luminaire makers the existing COB market landscape was selected for the smaller this also limits the options to by consulting many different form-factors (i.e. 12 x 15, 16 x 19 use alternative products from stakeholders, such as and 20 x 24 mm). For the larger different suppliers without the manufacturers of COB modules, form-factors (i.e. 24 x 24 and 28 x need to change their luminaire COB holders and LED luminaires. 28 mm) a square shape was designs. selected. This was to safeguard Although focusing only on the sufficient area for future integration mainstream COB market, with COB of additional functions and features, dimensions from 12 to 28 mm, as well as to ensure ease of manual this quickly resulted in a long list of handling in the case of smaller more than 50 different COB COBs. The 19 x 19 mm form-factor form-factors. A short list of five was added alongside the categories was derived, applying 20 x 24 mm category as a

Figure 2: compromise between cost For each COB effectiveness and long-term size, the remaining robustness of the specification. functional COB area (after subtracting the maximum LES area Note that the first phase of Zhaga from the total area) is COB standardization focuses only plotted as a function on the basic COB functionality, of the smallest COB dimension and does not include additional functions such as multi-channel LED driving or auxiliary sensors. Also, COB dimensions larger than 28 mm or smaller than 12 mm have not been taken into account (yet).

For each COB size, the functional Figure 3: COB area can be calculated by COB module subtracting the area of the specification including maximum light-emitting surface key dimensions (LES) from the overall area of defined according to the geometric the COB module. In figure 2, dimensioning and the remaining functional COB area tolerancing (GD&T) is plotted as a function of the method. Values of the different dimensions smallest COB dimension. For the for each COB category smaller COB form-factors, the are shown in table 1 rectangular shape ensures that at least 100 mm2 is available for further function and feature integration, whereas for larger square COB form-factors the remaining area is already sufficiently large. Mechanical Interface This GD&T system defines the basic Specification dimensions as nominal values and Also, another advantage when outlines the allowed variation in form using rectangular-shaped COBs GD&T method and size. Figure 3 shows an example is LES diameter maximization. For COB product specifications, of the center position and minimum This is because the creepage a wide range of different size of the electrical contact pads distance and clearance (C&C) mechanical interface definitions are and mounting holes as specified requirements between contact currently being used, and these according to the GD&T method. pads and active dies are not a vary significantly between the bottleneck in that case. different COB manufacturers. Also, not all the key tolerances Contact pads The resulting six COB form-factors are always included in the To avoid the need for manual defined by Zhaga allow COB-array accompanying product drawings. soldering, COB modules are often makers to focus on areas where This unnecessarily complicates the used in combination with COB holders. they can offer value-added design-in process for suppliers of For this application, the position and differentiation to customers, components such as COB holders, minimum size of the COB electrical such as thermal properties, heatsinks or optics. Moreover, contact pads are key dimensions quality of light or luminous efficacy. most of the COB specifications and therefore are also part of the For supporting companies supplying do not take into account the risk Zhaga specification. The required complementary products such as of tolerance stack-up, which is minimum size of the contact pads COB holders and optical elements, critical to determine the mechanical is actually a result of the overall the concise set of six form-factors fit between, for example, mechanical tolerance chain of both will help to proliferate the COB modules and COB holders. COB module and holder. accompanying ecosystem. Moreover, for lighting OEMs and Therefore, the Zhaga taskforce In order to avoid needlessly- customers, this Zhaga specification introduced a generic system for large minimum contact areas, simplifies the comparison and defining and communicating Zhaga requested data for the selection of products. engineering tolerances, a method actual tolerances in COB and called geometric dimensioning holder manufacturing instead and tolerancing (GD&T). of the usually-communicated commercial tolerances.

Table 1: Overview of the LED Module contact-pad positions Category W L Sx Sy ØH Dx Dy Lp (Dx,Dy), and minimum length and width of the C28x28 28.0 28.0 11.4 11.4 3.1 11.1 11.1 2.0 square contact area (Lp), for the different C24x24 24.0 24.0 9.4 9.4 3.1 9.1 9.1 2.0 COB categories. Also shown for the two C20x24 20.0 24.0 - - - 9.1 7.1 2.0 largest COB categories is the position of the C19x19 19.0 19.0 - - - 7.525 7.525 1.75 mounting holes (Sx, Sy), which have C16x19 16.0 19.0 - - - 7.525 6.025 1.75 a diameter ΦH (for all dimensions, the units C12x15 12.0 15.0 - - - 5.6 4.1 1.6 are mm)

A square-shaped minimum area to the position of the contact pads Mounting holes with rounded corners was agreed as listed in Table 1. In addition, the and mousebites upon to allow sufficient design keep-in zone is restricted by the LES For holderless mounting, freedom for the COB holder category. Each LES category has a the COB modules can have manufacturers. A rectangular- or maximum diameter for the optics optional mounting holes or indents triangular-shaped contact pad contact area (OCA) of the LED with a designated position and would also have been possible, module, which corresponds to a diameter (Figure 3). The larger but would have constrained the minimum reflector opening. COB categories (i.e. C28x28 position and direction of the and C24x24) can have mounting contacting beams in the The LES and OCA categories in holes suited to accommodate COB holder. the COB specification are the M3 screws. The smaller COB same as those used in the different categories can have indents at Next, the center positions of the Zhaga specifications covering the corners, also known as electrical contact pads were LED modules for spotlighting-type mousebites, with a radius designated, taking into account applications. Currently these intended also for M3 screws. typical creepage distance and specifications are Books 3, 10 and clearance (C&C) requirements. 11 (Books 3 and 11 are published, Table 1 shows the resulting Book 10 is in development), but in Thickness contact-pad positions (Dx, Dy) future they will be combined into For best performance and a and minimum contact-pad a single Book. secure fit of the COB holders it dimensions (Lp) for the different was necessary to limit the COB categories. The combination of a COB module thickness variation of the and a suitably-sized COB holder can COB modules to 1.0±0.15 mm. create a product that effectively Therefore, the thickness does Keep-in zone replicates a spot LED module as not include a thermal interface The keep-in zone defines the region described in either Book 3, 10 or 11. material (TIM). Usage of a suitable of the COB where it is permitted to TIM is always recommended but place LED components as well as Table 2 shows the resulting it should be either thin enough other features such as the dam maximum keep-in diameter both as to keep the COB within the surrounding the phosphor area. The a function of the LED module thickness tolerance or the TIM center of this keep-in zone coincides category and the LES category. area should be extended and with the mechanical reference point. The keep-in zone typically includes overlap with the holder. Outside this keep-in zone, the LED the dam surrounding the LES area. module is not permitted to have any Table 2: features that protrude above the Maximum keep-in LES category diameter (mm), which PCB top surface, with the exception depends on both LES of PCB tracks and contact pads. LES6.3 LES9 LES13.5 LES19 LES23 LES30 category and LED module category. C28x28 8.3 11.0 15.5 21.0 25.0 26.8 Note that the smaller The Zhaga specification defines the COB module sizes maximum keep-in zone diameter. C24x24 8.3 11.0 15.5 21.0 21.1 x cannot accommodate For a specific COB module, this the larger LES sizes depends not only on its COB C20x24 8.3 11.0 15.5 18.5 x x (indicated by x) category (i.e. the overall module C19x19 8.3 11.0 15.5 17.0 x x dimensions) but also on its LES category. The COB category limits C16x19 8.3 11.0 15.0 15.0 x x the keep-in zone diameter due

LED module category module LED C12x15 8.3 9.8 9.8 x x x either to the overall COB outline, or

Conclusion module-holder interfaces, can be Compliant and certified products In a very short period of time, expected in due course. Moreover, are listed on the Zhaga website and Zhaga members have worked Zhaga has already decided that are entitled to carry the Zhaga logo. together to produce the first the COB-holder-to-luminaire edition 1.0 of Zhaga Book 12. interface definition will be included After finalization of phase 1 of COB This defines a family of six form- in future editions of the Zhaga standardization, which is limited to factors, and includes critical Books covering LED modules basic COB functionality, work will be dimensions such as the position for spotlighting applications. started on a second standardization and minimum size of the electrical phase. This will aim to include contact pads, and the size of Testing for COB product compliance additional features and higher the keep-in zone. with Zhaga Book 12 will be carried integration levels, for example out by independent testing facilities multi-channel, optical feedback An updated version of the operated by one of several and sensors. specification, which will also Authorized Testing Centers include the definition of the COB appointed by Zhaga [1].

Remarks: [i] Chip-on-board (COB) is a manufacturing technology in which the LED chips are mounted directly onto a printed circuit board (PCB). The phosphor coating necessary to produce white light is either applied to each individual chip, or applied across the entire array References: [1] Certification & Authorized Testing Centers: www.zhagastandard.org/books/certification

The concept of the light-emitting surface (LES) has been developed by the Zhaga Consortium to enable comparisons of the photometric properties of different LED light engines. Stefan Lorenz, a Systems Architect with Osram GmbH, describes the theory behind the LES and how it applies to the different Zhaga Books.

The amazing speed at which specifications which separate This article deals with the LED technology is evolving the internal technology of the concept of the light-emitting has surprised not only light source from external surface (LES), as it was the experts in solid-state features necessary to maintain developed by the Zhaga technology. This development a long-term constancy in Consortium. LES is designed is a problem to those who need the application. to enable the easy evaluation to rely on a certain constancy of the optical emission of an in light-source design for longer Zhaga specifications describe LLE or LED module without than a year - which is everyone LED light engines (LLEs) and reference to its internal who wants to sustain a lighting related components including technology. solution or fixture for more LED modules and LED drivers. than that time. These specifications are called “Books” and define certain To solve this conflict, features of these LLEs and the Zhaga Consortium components which are needed is establishing a set of to keep them interchangeable.

Figure 1: Three „classic“ light engines that share common mechanical, electrical, and optical properties. Left: A light engine with large and homogeneous light-emitting surface (LES) i.e. the outer envelope of the lamp. Middle: A light engine with a small LES, using standard filament technology. Right: A light engine with a small LES, using halogen technology. All three light engines are compatible in most luminaires made for them

Compatible and So the first requirement for two information on colour (colour over Interchangeable LLEs to be interchangeable is that angle as well as colour related to The ability to interchange LED light the light emission takes place at a emission position), whereas the engines in one luminaire doesn’t comparable position on each LLE, LES is a purely intensity-based imply that one will get exactly the and in a comparable direction. concept for reasons of simplicity. same behaviour with all LLEs. The rough shape of the emission The disadvantage of ray files - This becomes obvious if you think area should also be comparable. bulkiness and need for computer- about substituting a 100 lm/W LLE Two LLEs with a similar LES then based evaluation - is addressed with a 130 lm/W LLE, for example. should produce comparable by the LES concept: a simple The new LLE will result in a more photometric properties in a luminaire. method to easily compare LLEs energy-efficient luminaire assembly, of different technologies. of course. The LES of the middle and right- hand bulbs in figure 1 are quite Figure 1 shows an example of similar in shape and light-emission Ideal LES, Actual LES “well-known interchangeable light direction, while the left-hand bulb’s and LES Range engines”, which have different LES has a completely different To be independent from a specific technologies and light-emission shape. The typical application of the implementation, Zhaga has to characteristics. LLE determines how similar two describe an “ideal” LES for each LLEs have to be for them to be application. This ideal LES is a Zhaga defines two degrees of interchangeable. Each individual simplified geometrical two- similarity that two (different) LLEs Zhaga specification defines its own dimensional surface, which can achieve in a certain luminaire. acceptable range. For the figure 1 characterises the ideal location The basic degree is “compatible”; light bulbs, all three might be called and shape of the light emission two LLEs are said to be compatible interchangeable as light sources in in the LLE. It does not need to if they have similar mechanical, shaded luminaires, but in open view, be an actual physical surface, thermal, and electrical properties. the left bulb is not interchangeable but is the idealized, simplified In other words, they are compatible with either of the others. area of light emission in an ideal if they fit into a luminaire designed interchangeable LLE. for this type of LLE, and if they The basic idea of the LES is well can be operated. The examples in represented even in the light bulb Figure 2 shows the ideal LES figure 1 are compatible in the example: Position, shape and for an LED module according to Zhaga sense. direction of light emission must be Zhaga Book 3. The LES has a similar in a light source to generate circular shape, a fixed diameter, The more advanced degree of comparable photometric properties and a fixed height above the similarity between LLEs is in a certain application. The LES LED module backplane. “interchangeable”. This term concept provides an easy method Figure 2: includes “compatible”, and adds, to describe and compare these A Zhaga Book 3 LED on top, a comparable photometric parameters in abstract specifications module. The Ideal performance. Thus, in order to and actual light sources. Light-Emitting Surface evaluate interchangeability, a (LES) is indicated as blue disc. Note that suitable description of photometric the disc is elevated properties is needed. Beyond the above the actual LED Light-Emitting Surface module’s physical features in this example Not all optical properties of an LED The Light-Emitting Surface light engine can be described by the The primary concept developed and LES concept. Some, like the The “actual” LES of an LLE used by Zhaga to judge comparable luminous flux, are better specified implementation might deviate from photometric properties in different separately and independently. the ideal LES in several aspects LLEs is the light-emitting surface Others, like the far-field luminous such as size, homogeneity, (LES). This characterises the area intensity distribution, are associated symmetry and vertical position and position of light emission from with the LLE, but not directly (height). The allowed degree of an LLE in a general way, so that connected to the LES. variation from the ideal LES (the LES the balance is kept between “range”) depends on the application, independence of technology and The information on full near- and and is specified such that all LLEs easy evaluation of similarity in far-field emission of a light source is which are within the allowed the application. usually provided in the form of ray variation range will produce files. These contain sufficient comparable photometric outputs Unlike classical light sources (such statistical information to simulate the in the application. as those in figure 1), normal LLEs optical properties of an LLE by do not emit light in all directions. software. They can even contain

Figures 3 a&b: (a) LES height range diameter. This range is depicted by Extra Information: for a Zhaga Book 3 the ring in figure 3. The outer Zhaga Book 7 module. The vertical diameter of the actual LES is Zhaga Book 7 describes rectangular position of the LES required to be within this ring. LLEs with an external driver, can be anywhere in the indicated range which are often used in luminaires (including below the formerly equipped with linear physical surface of the Differences from fluorescent tubes. To allow for a module/LLE). certain degree of versatility, (b) LES diameter range Physical Features for the same module. An example of an actual LES is the LES definition in Zhaga Book 7 The actual LES outer shown in figure 4, for a real LED is minimal, but requires extra diameter needs to be module especially suitable for information to be provided with within the indicated ring narrow beam applications. The top each LLE. The only common view shows that the LEDs form a property of the LES in Zhaga Book 7 non-circular pattern. The LES is that it is located at the top of the diameter range is superimposed LED module. This is already in blue. The actual LES, which is sufficient for many applications limited by a circle around the LEDs, in which Book 7 LLEs are used. Figure 4: Actual LES shown in is indicated in red. The side view red and LES range shows the vertical position of the More information on the structure shown in blue for a actual LES and the LES range. of the LES is given in Zhaga Book 7 Book 3 LED module. The actual LES is within the LES by a luminance measurement in Top view: Actual LES is smaller than range, so the LED module shown a test luminaire (Figure 5). the maximum LES here is compatible with other The resulting image gives an diameter, but larger Zhaga LED modules. impression of the homogeneity than the minimum LES that can be achieved with the diameter. Side view: Actual LES is above the tested LED module. The user can individual LED domes, Optics Design for LES decide if the appearance of the and well within the LES The concept of interchangeable LLE is suitable for his application. height range LLEs puts a burden on the design of the luminaire optics, if the luminaire’s LLE is meant to be Additional Restrictions: interchanged. The LES is the Book 3 and Book 4 commonality that an optics A more detailed specification designer can expect from the and some limitations are needed various LLEs that the luminaire for the high-intensity LLEs in Book 4 Figure 5: Two standardized should operate with. As a and the circular LED modules in LES images from consequence, optics design Book 3, for example. Here, Zhaga Book 7 modules, should not be based on a single more specifications on the inner with either sparse or LLE, but rather on the ideal LES structure of the LES are necessary dense LED placement on the LES. Also shown laid down in the Zhaga to ensure that the LLE is is a typical Book 7 specification (Book) in question. interchangeable and works LED module Interchangeability at the Zhaga satisfactorily with typical luminaire level is then automatically optics. A minimum size for the ensured without additional efforts. LES is ensured as well as the Further optimization with ray files already-specified maximum size. would be counterproductive, as it Also, the LES needs to be would reduce the interchangeability sufficiently homogeneous to avoid in favour of a single peak design. artefacts - especially in strongly directional luminaires.

Figure 3 shows the LES height Supplementary LES The ideal LES shapes are circular for range and LES diameter range of Information Book 3 and rectangular for Book 4 a spotlight Book 3 module. The inner structure of the actual (Figure 6). Deviations from the LES The vertical position (height) of the LES can have quite an impact can result in unexpected beam actual LES can be within a range on comparable photometric shapes. The actual LES can be only around the ideal LES height. performance in certain applications. a little smaller than the ideal LES For that reason, some Zhaga Books size, but at the cost of deviations in The diameter of the actual LES have extra requirements on the LES. the beam shape. The acceptable can be smaller than the ideal variation sets the lower limit in the LES diameter, down to a minimum LES range.

Figure 6: Summary Typical Book 4 LED The challenge of defining a module, showing technology-independent and simple the maximum LES description of light emission from dimensions LED light engines has been accepted by Zhaga. The LES concept is a simple method to ensure photometric comparability of different LLEs. Zhaga Books specify an ideal LES, with an allowed range of actual variations just small enough so that the individual LLEs are still comparable in their application. The actual LES can be easily compared, without reference The actual LES must have uniform LLE deviates too much from the to the actual LED technology inside luminance and a high degree of ideal LES. All parameters have some the LLE. symmetry, to avoid hotspots or range of freedom, which can be asymmetries magnified by the exploited to construct actual LLEs, Since its introduction by Zhaga, the luminaire optics. Both Zhaga Books but the sum of all deviations must concept of LES is well accepted in 3 and 4 require the determination of be small enough to avoid non- the lighting community as an easy centre balance and uniformity. In comparable behaviour in the categorisation for the new addition, the circular LES of Zhaga luminaire optics designed for the opportunities of LED lighting. Book 3 is evaluated for rotational typical LES. symmetry, while the rectangular LES in Zhaga Book 4 needs horizontal Both Books 3 and 4 have a very and vertical symmetry well-defined LES, due to the typical measurements. application requirements they are designed for. The well-defined LES All these limitations and guarantees that interchange of LED measurements are implemented in light engines is possible with Books 3 and 4 to ensure that no minimum variation.

Remarks: [1] An LED light engine (LLE) combines one or more LED modules with an LED driver. The driver can either be integrated inside the LLE, or the LED module(s) and driver can be separate from each other. The light-emitting surface (LES) is associated either with the integrated LLE, or with the LED module in cases where the driver is separate. In this article, the terms “LLE” and “LED module” are used interchangeably

Thermal fit is an essential aspect of determining if LED light engines and luminaires are compatible with each other. Zhaga specifications include a standardized data set to enable users to perform an easy check of the thermal fit conditions, as explained by Uli Mathis from Tridonic and Toine Staring from Philips Lighting.

Specification of the thermal Introducing the Thermal The thermal resistance of the interface of LED light engines Interface luminaire is measured with a and LED modules is an Like all light sources, LED light thermal test engine, which has essential part of ensuring sources produce heat. This heat is dimensions that are similar to that Zhaga components are transported away from the LED light those of an LED light engine. interchangeable. Through its source via a heat sink that is The heat generated by this thermal various specifications, typically part of a luminaire. test engine is provided by a resistor Zhaga has developed methods The description of this thermal that is supplied with a rated current. to evaluate the thermal interface includes the requirements By measuring the temperature

compatibility or thermal fit for the heat flux from the light tr at a reference point on the of different light engines or source to the luminaire and further thermal test engine and the

modules with a particular to the ambient of the luminaire. temperature ta in the vicinity of luminaire. the luminaire, the thermal resistance

As shown schematically in Figure 1, Rth can be calculated from the

There are different requirements the path of the heat flux from the power Pth that is applied to the for replacing an LED light engine LED light engine to the ambient heating resistor.

depending on who carries out contains a thermal resistance (Rth).

the replacement. This is taken The magnitude of this thermal For Rth, thermal resistance: into consideration by Zhaga resistance depends on the surface when specifying different types of the heat sink (luminaire), tr - ta R = (1) of light engine. End users who the contact material between th Pth typically replace a socketable the LED and the heat sink, light engine with a new one and on the thermal power. have different requirements Figure 1: from professional users, such Schematic diagram of a luminaire in a recessed as luminaire manufacturers, environment. The LED who use products from several light engine (LLE) suppliers in the same type of generates heat at a rate luminaire. of Pth while Pth,rear is the heat flux (or thermal power) of the LLE This article discusses the through the interface thermal interface between with the luminaire LED light sources and heat sink. The path of the heat flux (dotted luminaires, and provides ways arrow) from the LLE to determine the thermal fit for to the environment both end users and luminaire is characterized by a manufacturers. thermal resistance Rth

Table 1: Meanwhile, the maximum allowed Evaluation using Evaluation using Alternative ways for an thermal resistance of the LED light thermal fit code P* thermal resistance Rth end user to evaluate engine (R ) is given in the whether an LED light th,max Light engine Thermal fit code P* = 20 R = 5.0 K/W @ P = 15 W manufacturer’s literature, and is th,max th engine has a thermal fit with a luminaire calculated: Rth = 4.0 K/W @ Pth = 10 W Luminaire Thermal fit code P*max = 25 Rth = 3.5 K/W @ Pth = 20 W

For Rth,max, max. thermal resistance: Thermal fit is OK because Thermal fit is OK because Rth P* value of light engine (20) is value of luminaire is less than Conclusion t - t less than P*max of the Rth,max value of light engine r,max a Rth,max = (2) luminaire (25) (5 K/W) Pth

Where tr,max is the maximum operating temperature of the Replacement by Luminaire • Total thermal power (Pth) of the light engine. Manufacturers light engine

Luminaire manufacturers have • Thermal power (Pth,rear) at the rear many possibilities for calculating of the light engine Replacement by End Users the thermal fit of light sources, • Maximum operating temperature

If an end user is going to replace an including Zhaga light engines, (tr,max) of the light engine

LED light engine, this procedure in their luminaires. Approaches • Rated ambient temperature (ta) of must be as simple as replacing an such as using simulation programs the luminaire incandescent lamp. The thermal fit or performing measurements in a is clearly defined if the thermal laboratory will allow a very precise Evaluation of the thermal fit resistance (Rth) of the luminaire is determination of the thermal fit. There are two ways to evaluate the smaller than or equal to the thermal fit of a Zhaga light engine in maximum allowed thermal Based on the thermal power that is a luminaire. The first method is resistance (Rth, max) of the provided in the data set of the light simulation of the thermal fit. The light engine. Even so, a simpler engine, the expected temperatures temperature tr at the reference point method has been worked out can be calculated for the luminaire. is calculated using the dimensions by Zhaga. The reason is that If the calculated temperature is of the luminaire, the thermal power the dependence of the thermal below the maximum value that is Pth of the light engine, and the resistance on the applied thermal specified for the light engine, ambient temperature ta. If tr ≤ tr,max power complicates matters. the thermal fit is OK in combination then the light engine fits in the with this luminaire. luminaire from a thermal point The method developed by Zhaga of view. consists of a coding system which By measuring the temperature at works in a similar way to the thermal the thermal reference point(s) of The second method is measurement fit of incandescent lamps. In this the light engine, the thermal fit can of the actual temperature inside the case, the power of the lamp is be confirmed. luminaire when operating under compared with the maximum rated conditions. If tr ≤ tr,max then the allowed power in the luminaire For replacing the Zhaga light engine thermal fit of the Zhaga light engine (e.g. 60 W maximum). by a similar type of light engine from is confirmed. the same manufacturer or from For Zhaga-based LED light engines another manufacturer, a professional the equivalent fit is coded with P*. lighting expert can make a simple Conclusion This value P* is a combination of calculation to check the thermal fit Zhaga LED light engines and the maximum allowed temperature of the replacement product. Zhaga LED modules are supplied and the actual thermal power of the He only needs to compare the with a standardized data set which light engine. The luminaire will be thermal power and the thermal allows an easy check of the thermal marked with P*max and the light limits of the new light engine with fit of the LED light source with engine with P*. the original one. the luminaire.

Table 1 gives an example of how There are several methods to thermal fit codes can help a Thermal data evaluate the thermal fit conditions. consumer in the decision process The following thermal data are These are carefully selected to meet for purchasing or replacing a offered for Zhaga LED light engines the needs of light engines which are socketable LED light engine. that are intended for use by replaced either directly by the end luminaire manufacturers: user, or by professionals such as luminaire manufacturers.

Enabling LED modules and LED drivers to be fully interchangeable at the component level requires a specification for the electrical interface between the driver and module (DMI).Arnulf Rupp of Osram GmbH, a member of both the Zhaga Consortium and MD-SIG, explains the role of both organizations in developing and implementing a consistent, easy to use, cross-vendor DMI specification.

The rapid evolution of LED This calls for stable, easy to dimming interfaces and power technology has catapulted use and reliable design-in grid voltages. A different solid-state lighting (SSL) from methodologies based on well- solution had to be found. spearhead innovation into a defined interfaces among the LED drivers and LED modules, phase of steady market growth building blocks for LED lighting. if not integrated in one product, within only a few years. remain separate building The new phase of LED lighting The Zhaga Consortium has blocks, and the system brings its own challenges. done a very good job in integrator must manage the While the benefits of LED- providing terms and definitions matching of components equipped lighting fixtures to describe many of those along the DMI interface. over products based on interfaces in a vendor- and traditional light sources is technology-neutral way. now indisputable in most Until recently, however, Demand for Standardizing applications, LED technology Zhaga lacked definitions for the DMI itself is still in rapid development. the interface between the Driven by the need for a flexible Keeping designs up to date LED driver (also known as matching of components, LED driver and competitive leads to electronic control gear, or ECG) manufacturers invented adjustable frequent redesign cycles, and the LED module. or programmable constant-current which the lighting industry was drivers capable of covering a wide not required to manage back From its outset, Zhaga range of load conditions in one in the days of halogen, purposely excluded the driver- product. Such products are often fluorescent and high-pressure to-module interface (DMI) called window drivers, current- discharge lamps. from its scope, because adjustable drivers or programmable standardization in that area drivers. A multitude of techniques From design to delivery, even was considered to be limiting to for setting the output current is the availability of certain design freedom and technical available in the market; technology generations progress. At that time, it was voltage-controlled output current, may be an issue from time expected that LED drivers and resistor setting, programming to time. Updating designs, LED modules would always be through the DALI line, programming adapting LED drive currents designed as a system, similar to through a dedicated setting for ever-improving LED lumen driver-integrated light engines interface, interfacing with additional efficiencies, and redesigning and LED retrofit lamps. circuits on the LED module, LED layouts to accommodate programming through modulated the latest in technology, have all The industry, however, faced signals on the mains input, and become time-consuming and availability issues for all the near-field communication. expensive baseload activities in desired combinations of the development departments features such as form factor, Even within the very common of the lighting industry. photometric properties, resistor-settable products,

the actual resistor values for setting provides a standardized method of fulfill many of the typical industry a given current may differ from one current setting and will introduce requirements for the DMI. vendor to another. In addition, the well-defined parameter sets for both terminology used by the manufacturers LED drivers and LED modules. MD-SIG defined a set of minimum to specify output characteristics, requirements the specification has operating ranges and setting It is not the aim of LEDset1 to to address. This minimum set also methods have become vendor- provide a one-size-fits-all solution. respects the needs communicated specific in many details. As an LEDset1 rather targets a wide range by Zhaga for independent example, the specified output of simple constant-current LED interchangeability of drivers and voltage and current ranges may or boards connected with output- modules. The minimum feature may not include margins for setting current-adjustable drivers. requirements are: tolerances or current ripple effects. The system integrator still has to verify key parameters defined in the • Output current setting at the The confusion and inconsistency in parameter set for component matching. production line of the fixture OEM the market leads to a strong need • Plug and play option with the for harmonization and standardization. MD-SIG specifications are publicly current setting circuit included on At the same time, the existence of all available on the organization’s the LED module these technologies has largely website (md-sig.org). The use of • Cross-vendor parameter set for eliminated the initial concern that the LEDset logo on products, specifying window drivers standardizing the interface between however, requires companies to • Live current adjustment e.g. for an the LED driver and LED module be a member of MD-SIG. optional thermal de-rating would limit design freedom and • Interfacing with multiple equivalent technical progress. A set of The LEDset1 information interface is LED modules connected in current-adjustable window drivers, already available for download on parallel and/or in series which may even have overlapping the MD-SIG website. It defines how output voltage and current ranges, the output current is set during The LEDset1 interface uses a simple is an ideal situation for designing luminaire production or through analog technique to realize the new LED luminaires and for information exchange between required features. A LEDset1 driver upgrading of existing products. driver and module. The related acts as a current-controlled current What remains is the need for a power interface, defining the source. In un-dimmed operation, consistent, easy to use and parameter set for the output the driver output current equals the cross-vendor-standardized DMI characteristics of the driver and current Iset at the LEDset terminal interface specification. This is where the operating range of the module, multiplied with a fixed factor of one a new industry alliance, the Module is currently a work in progress. thousand. For the supply of the Driver interface Special Interest Further specifications may follow, setting circuit, the LEDset terminal Group (MD-SIG), aims to serve for example a digital interface for provides a fixed reference voltage the market. LED module to driver of 5 V. The setting circuit is a current communication and programming. sink connected between the LEDset terminal and the lower voltage (LED-) MD-SIG and LEDset output terminal. In the simplest MD-SIG is a global lighting-industry LEDset Interface case, the setting circuit can be a consortium introducing LEDset as a Characteristics simple resistor with a value Rset of: multi-vendor specification for the MD-SIG has chosen to start with a interface between LED drivers and specification harmonizing the very 5V R = ∙ 1000 (1) LED modules. The alliance has a common analog current-setting set Iout global focus and is open to all methods. Even such simple and interested parties. It aims to simplify lightweight technology can already where Iout is the desired output current. matching of components and to Figure 1: reduce the interchange risk resulting Push-in resistor from deviating terminologies for the for configuring the parameters defining the DMI. drive current on the luminaire production line. The corresponding When used in combination with electrical setup is specifications created by the Zhaga shown in figure 2 Consortium, LEDset will enable manufacturers of LED luminaires to interchange LED modules and LED drivers made by different vendors. For that purpose LEDset1, the first specification released by MD-SIG,

Figure 2: A setting circuit using with the requirements. For the use of the LEDset1 logo on the product, a LEDset1 driver with an external coding resistor MD-SIG requires proper (R ). The value of R set set documentation of testing results by determines the driver the member making the product. output current (Iout) according to Equation 1 Zhaga will include the DMI in its third-party certification scheme along with the verification of other Zhaga-specified properties to ensure full interoperability with independent testing.

Conclusion The Module Driver interface Figure 3: An alternative setting Special Interest Group (MD-SIG) circuit, where the writes specifications for a smart control circuit including electrical interface between LED the coding resistor drivers and LED modules. This is (Rset) is on the LED module the critical link essential for independent interchangeability of SSL components. Zhaga is using MD-SIG specifications in its latest driver and module Books. This is an important step forward in the maturation of SSL technology. The cooperation between Zhaga and MD-SIG now enables a higher degree of cross-vendor interchangeability at the component Figure 1 illustrates the case of a specifications for both components level. This simplifies design work, coding resistor plugged into the as well as a DMI specification to helping to reduce R&D costs, driver for setting the drive current. connect them. Zhaga has created and increases component The schematic in figure 2 shows the a document structure with one availability for new designs and electrical setup corresponding to common LED driver specification, product upgrades. the diagram infigure 1. The setting or Book, for all LED drivers circuit may also be installed on the (Book 13) and multiple Books for the LED board; this would require a different LED module form-factors third wire connecting the LEDset (e.g. Book 3, 7, 11 etc.). terminals at the LED module and the driver. Zhaga decided not to duplicate the effort for the development of a DMI Figure 3 illustrates a case where specification but rather to adopt an the coding resistor is on the LED external specification fitting its module together with another needs. Both sides of the Zhaga temperature-controlled current system will reference the LEDset1 source to realize the desired interface specification as the temperature de-rating. recommended DMI. Besides the The specification document DMI reference, Book 13 includes provides more details on these the proven set of Zhaga driver application cases and further form-factor designations. Thus, options on how to apply LEDset1. it enables full mechanical and electrical interchangeability with a limited set of well-defined matching Driver Module Interface parameters. LED module books in Zhaga featuring the DMI will follow. Independent interchangeability of drivers and modules, MD-SIG specifications provide the architecture Zhaga is now testing instructions for vendors or aiming for, requires independent test houses to ensure compliance

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