The PCB Magazine, May 2015

& Etching

Electroplating May 2015 Plating 22 Through-Holes with Different Geometry: A Novel and High-Productivity Process

ENEPIG: 44 The Plating Process

May 2015 • The PCB Magazine 1

13th ANNUAL MEPTEC MEMS TECHNOLOGY SYMPOSIUM Enabling the Internet of Things: Foundations of MEMS Process, Design, Packaging & Test

MEMS based products are key enablers in the Internet of Things (IoT) Wednesday, May 20, 2015 revolution. The availability of large numbers of reliable and cost-effec- Holiday Inn San Jose Airport • San Jose, California tive MEMS sensors and actuators KEYNOTE SPEAKER has driven an explosion in the num- DIAMOND SPONSOR ber of IoT applications to reach the Creating a Trillion Sensors Based Future market. The Internet of Things is Dr. Janusz Bryzek pushing MEMS technology to new Chair, TSensors Summits levels of performance and bringing forth new requirements. Sensors are one of the eight exponential technologies enabling growth of goods and services faster than This event will showcase advances growth of demand for them. Exponential technologies enable Exponen- in core technologies that form the tial Organizations (ExO), which demonstrate sales growth to a billion SILVER SPONSOR foundation of the creation of MEMS- dollars in one to three years. New Exponential organizations are expected based products. Experts from the to replace 40% of Fortune 500 companies in the coming decade, in a field will present the latest innova- similar mode to Kodak replacement by Instagram in 2012. Presented will tions in MEMS fabrication processes, an amazing showcase of available sensor based products. packaging, assembly, & test. Insight will be provided as to new technolo- EXHIBITING COMPANIES TO DATE gies, materials and software that will fuel the creation of new devices coupled with traditional MEMS technologies to address new markets and new requirements for the Internet of Things. We explore how the four foundations of MEMS technologies are expanding to include such excit- ing new techniques as 3D printing, flexible electronics and novel materials. We hope you will join us to learn from experts about practical, com- mercial and significant technology advances in MEMS Test, Design, Pro- cess and Packaging, each driving key MEMS enabled products. Come hear about the technologies that form the “Sensory System” at the heart of the Internet of Things – it’s not just about the network!

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REGISTER ONLINE TODAY AT MEPTEC.ORG May Featured Content Plating & Etching This month, features from Michael Carano (RBP Chemical Technology), a team from Dow Chemicals Company, and George Milad (Uyemura) share their perspectives on plating and etching issues.

8 Optimization of Acid Copper 22 Electroplating Through-Holes Electrodeposition Processes for with Different Geometry: High-Throwing Power DC Plating A Novel and High-Productivity by Michael Carano Process by Elie Najjar, Leon Barstad, Jayaraju Nagarajan, Marc Lin, Maria Rzeznik and Mark Lefebvre

44 ENEPIG: The Plating Process by George Milad

4 The PCB Magazine • May 2015

C ont e nts may 2015 Volume 5 Number 5 the definitive interactive magazine dedicated to the global PCb industry thepcbmagazine.com

Interviews Video Interviews 50 NEW Multi-Part Interview! 20 ENIG & ENEPIG IPC Standards Update A Conversation (and Day) with Joe Fjelstad

54 The Importance of Harmonized Standards that Benefit All Pete Starkey Interviews Amphenol’s Sean Keating 60 Five Keys for Success in PCB Manufacturing

columns 56 Best Practices 101: Part 7 by Steve Williams

News Highlights 42 Market

52 Supplier/New Product 64 Quick-Turn Circuit Board Shops by Karl Dietz 62 Mil/Aero007

70 Top Ten PCB007 Highlights

Extras 72 Events Calendar

73 Advertisers Index & Masthead

6 The PCB Magazine • May 2015 feature

Optimization of Acid Copper Electrodeposition Processes for High-Throwing Power DC Plating by Michael Carano quantify the capability of a fabricator to prof- RBP Chemical Technology itably produce traditional boards. The ability to image conductor lines, and perhaps even more important, the insulating airspace be- Introduction tween them, is considered a key characteristic. Perhaps one of the three most fundamen- With surface mount components, a dramatic tal aspects of printed circuit fabrication is the decrease in plated via hole diameter require- metallization and electroplating of through- ments occurred, and as a result, via holes have hole vias and blind via interconnections. Ide- become simple vertical interconnections. Now, ally, one should also include fine-line imaging under competition from laser drilling, both of increasingly smaller feature sizes and via for- drill bit and machine technology have driven mation, whether by mechanical or laser meth- mechanical holes capability much smaller. ods. Indeed, the foundation of technology In the most recent release of the IPC Tech- roadmaps should, at the very least, encompass nology Roadmap, PTH and blind via diameters a discussion of line widths and spaces, PTH and aspect ratios have been defined as to the and blind via aspect ratios, and a metric that technology sector where the boards are used. In defines acceptability of plating uniformity and order to provide a list of key attributes (layer throwing power. These same parameters have counts, board thickness, number and diam- been used for nearly four decades to quickly eters of vias, etc.) for the PCB, emulators are

8 The PCB Magazine • May 2015 feature

Optimization of Acid Copper Electrodeposition Processes continues employed. Emulators (synthetic) are representa- For purposes of this paper, throwing power tions of a category of product, combining the at- is defined as the minimum electroplated thick- tributes common to the type to avoid concerns ness in the center of the PTH, divided by the about disclosure of specific company-proprietary thickness on the PTH surface (excluding copper designs. Technologists from around the world were asked to provide their respective view of the PCB technology required for the emulator. This exercise is critical in developing and understanding roadmaps. As an example, Table 1 below lists the minimum mechanical via hole sizes for the various emulators. Table 2 depicts the maximum aspect ratio of mechanically drilled plated through-holes for the respective emulators.

The Challenge It is quite clear from the two tables that there are rather high-aspect ratio vias that must be plated. It is understood that it is desirable to achieve as close to 100% throwing power as possible. At a minimum, market surveys have shown that for reliability, productivity, and performance purposes, a minimum of 80-85% throwing power is required. Further, process engineers desire to minimize plating on the conductor traces in order to minimize under- Figure 1: Throwing power: 1.0 mil minimum hole cut and circuit width destruction due to final thickness and 1.3 mil surface thickness. Throwing etching. power is 1.0/1.3 mil, or 77%.

Table 1: Minimum hole diameter for mechanically drilled vias (mm, rounded to whole number). (Source: IPC Technology Roadmap, 2015)

10 The PCB Magazine • May 2015 feature

Optimization of Acid Copper Electrodeposition Processes continues foil). Figure 1 illustrates the definition of throw- K = Solution resistance ing power. d = Hole diameter While in Figure 1 the throwing power L = Length of hole is 77%, one would prefer throwing power of 100%. Electroplating of high-aspect ratio It is important to keep this in mind when through-holes becomes increasingly more dif- designing plating processes for high-aspect ratio ficult as via diameters decrease and board thick- circuit boards. As circuit boards become more nesses increase. Figure 1 depicts a condition complex in their designs, more attention must aptly named “dog-boning” for its thinness in be paid to plating cell design, plating chemistry, the center of the via. anodes and plating racks, electrical connections The following equation illustrates a model and solution agitation. This paper will also pres- that provides insight into the difficulty factor ent various techniques on improving and en- encountered when aspect ratios increase. It is hancing throwing power for high-aspect ratio not as simple as it looks. As the model illustrates, plated through-holes, with a focus on direct board thickness has a much greater influence current (DC) plating. on degree of difficulty than does via diameter. Essentially, board thickness directly influences Acid Copper Electroplating: ohmic resistance through the via. Resistance is Theoretical Aspects inversely proportional to plating propagation. In order to enhance plating uniformity (defined not only as plating thickness across the PCB surface but in the via as well), engineers should understand that there are several factors that influence plating uniformity. The Fishbone diagram below details in concise fashion those parameters that influ- Where: ence throwing power, plating distribution E = Voltage drop down hole (energy lost) and overall quality of the finished printed cir- J = Cathode current density cuit board.

Table 2: Aspect ratio, mechanically drilled hole via (max ratio).

May 2015 • The PCB Magazine 11 feature

Optimization of Acid Copper Electrodeposition Processes continues

Figure 2: These factors and their influence on plating distribution will be presented throughout this paper.

Acid Copper Electroplating for High-Aspect the board thickness increases, ohmic resistance Ratio PCBs: Practical Aspects dominates and addition agents have less of an For any process engineer, getting a handle influence[2]. In this case, mass transfer of the on the key elements involved in the process will plating solution into the vias is critical. How- provide the insight and understanding required ever, with the higher-aspect ratio holes, mass to achieve optimum plating results. The first transfer gives way to ohmic resistance. In or- part of this equation is to recognize the rela- der to compensate, one needs to reduce the ca- tionship and interactions of the plating chem- thodic current density and also reduce plating istry (inorganic and organic). solution resistances. The latter is accomplished by increasing electrolyte conductivity, reducing Influence of the Organic Additives and resistances in plating cables and other cell de- Plating Electrolyte (inorganic) sign enhancements that will be mentioned in The organic addition agents utilized in the the next section. Since it becomes increasingly plating solution have an influence on plating difficult to achieve near 100% throwing power distribution and throwing power under certain in aspect ratio holes of 10:1 and above, the plat- conditions. The additives distinctively influence ing electrolyte must be set-up to maximize plat- this behavior when charge transfer and ohmic ing solution conductivity. This is accomplished resistance dominate the plating system behav- by increasing the sulfuric acid concentration ior. However, as the PTH diameter increases and and reducing the amount of available copper

12 The PCB Magazine • May 2015 feature

Optimization of Acid Copper Electrodeposition Processes continues ions in solution. Of course, one cannot reduce the copper ions in such a way that the limiting current density will be quite low. This is where mass transfer becomes increasingly important. And mass transfer is dependent on diffusion- the movement of ions and additives through the plating electrolyte. Organic additives will also affect the grain structure, leveling and physical properties of the deposit. Strict control of the additive chemistry requires instrumentation such as cyclic voltammetric stripping (CVS) and perhaps ion chromatography. Additional agent imbalances will reduce the ductility of the copper deposit, thin plating at the knee of the via and poor Figure 3: Air bubble entrapment in via leading to leveling. plating void.

Influence of Mechanical Aspects of the Process In addition to the influence of the organic resistive when present as a cloud or foam of additives and the inorganic chemistry, there bubbles; and, the general plating rate enhance- are several other factors that influence plating ment is modest despite several possible param- distribution and throwing power. One major eters for adjustment. The least appreciated char- influence is solution movement or agitation. acteristic is the resistivity, which can lead to Agitation influences mass transport. As one an increase of electroplating power of 25–30% will recognize, the organic addition agents af- and is therefore a significant electrical cost fac- fect plating distribution and throwing power, tor. It also generates environmental pollution among other attributes. And mass transport of through dispersion of air bubbles. In addition, the plating solution is key to “pushing” these these tiny bubbles can lodge into the through- additives from the bulk plating solution to the holes and blind vias, leading to a reduction in cathode (circuit board to be plated) surface. One plating thickness or voids[1]. This micro-bubble can look at agitation as solution mixing and ag- void inducing condition is well-documented in itation at the interface of the cathode and solu- the industry and can be seen in Figure 3. tion boundary layer. Solution agitation of the Conversely, solution movement supplied by copper plating electrolyte maybe accomplished eductor agitation is much more effective than with air agitation, eductors, solution impinge- air. When agitation is supplied via eductors, ment or cathode bar movement. The main pur- the solution movement is significantly more poses of agitation have been stated many times uniform across the panel surface. One can de- and include: scribe this as ‘laminar flow.’ With air agitation, the solution is moving in a turbulent fashion • Elimination of solution stagnation and and is often quite non-uniform. This turbulent dispersal of reaction products flow creates areas within the plating cell con- • Increase of deposition rates by mass sisting of dead spots, which appear as if there transfer enhancement is no or very minimal agitation in that portion • Dissipation of heat at electrode/solution of the cell. This is a recipe for disaster. When interfaces[1] this condition occurs, plating uniformity is not ideal and the cosmetics of the deposit as well as Air agitation suffers from three main dis- the physical properties suffer. advantages: It has a chemical oxidative action Eductors, on the other hand, can be imple- towards solution constituents; it is electrically mented at a very low cost with respect to retro-

May 2015 • The PCB Magazine 13 feature

Optimization of Acid Copper Electrodeposition Processes continues fitting any of the plating cells. This author has power ills on its own. As mentioned above, there had documented success with respect to im- are other factors including the organic addition proving throwing power and plating distribu- agents and the composition of the plating elec- tion. More uniform plating distribution helps trolyte itself. And many of these factors interact to reduce the plating cycle time (everyone likes with each other. As the graph in Figure 6 below higher productivity and efficient use of capital). shows, when the organic addition agents (in Secondly, minimizing plating thickness on the this case the carrier component of the plating surface of the board while enhancing throwing additives) are in the optimum concentrations, power in small diameter vias will provide less the throwing power is significantly better than opportunity for circuit line width reduction due when eductors are used to supply the solution to etching. Fabricators should always keep this movement. In this study, the circuit board test fact in mind especially as one migrates to 3 mil vehicle was 0.093 inches thick and the smallest lines and spaces. Figure 4 shows an actual plat- via diameter was 0.008 inches. Cathode current ing cell (without chemistry) with eductors. density was set at 25 ASF (amps per square foot). Figure 5 shows a single eductor pod as a One should not underestimate the im- close-up. These eductors should be mounted portance of plating cell design and geometry on manifolds as shown in Figure 4. This type of when it comes to optimizing throwing power agitation set-up requires a 2.5–4 HP pump for and overall plating distribution. Factors such as every 4000 liters of plating solution. anode-to-cathode distances, anode length and Of course, solution movement (eductor ver- placement and plating rack construction/design sus air agitation) cannot cure plating throwing greatly affect plating uniformity. With respect to rack design, a picture frame rack (multiple rack points around the periphery of the board) will provide more uniform current distribution as opposed to a rack with a few attachment points at the top or side of the panel. In addition, anode length should be 3–4 inches shorter than the length of cathode. This will aid in mitigating excessive plating on edges of the panel. With primary distribution, the electron potential field depends solely on cell geometry including anode length and placement (Figure 7). It is possible to use floating shields in the plating tank in order to divert current from those areas of the circuit board most prone to over- plating.

Figure 4: Photo of plating cell with bottom up Figure 5: Close-up view of a single educator, also educators. known as a pod.

14 The PCB Magazine • May 2015 feature

Optimization of Acid Copper Electrodeposition Processes continues

Figure 6: Influence of air versus eductors on throwing power.

Figure 7: Current flux lines follow path of least resistance leading to over-plating and poor distribution.

Plating rack materials fabricated out of cop- ondary current distribution. Secondary current per (Plastisol coated) provide more electrical comes into play through a factor known as po- conductivity than stainless steel material. This larization. Polarization refers to the additional is an important fact for thicker panels and high- potential required above the equilibrium po- aspect ratio via holes. tential to drive the deposition of the metal to Fortunately for plating difficult circuit be plated. (Keep in mind that factors involved boards, there is another factor to consider: sec- in primary current distribution should be op-

16 The PCB Magazine • May 2015 feature

Optimization of Acid Copper Electrodeposition Processes continues timized in addition to manipulating second- Large grained copper anodes dissolve uneven- ary current distribution.) The potential is de- ly, leading to heavy sludging and potential for termined by Ohm’s Law, which is the solution impurities and particulate matter to enter the resistance between the anodes and cathodes. plating solution. An example of different anode Additional resistances arrive through the volt- quality is shown in Figure 8. age required to corrode the anode and the resis- There are three different anodes from three tance required to reduce the metal ions to metal different suppliers, each claiming quality an- at the cathode. odes for printed circuit fabrication. Note that In order to improve throwing power and each anode looks much like the other. plating uniformity, one can increase the con- Each anode ball was cut with a diamond saw ductivity of the plating electrolyte and increase to reveal structure. Figure 9 shows an SEM of the polarization. Polarization and conductiv- each of those. Clearly there is a distinctive dif- ity are both dependent on solution operating ference among the grain structures and phos- temperature, solution agitation and cathode phorous (shown as the dark areas). To read current density. The main consideration is rec- more about anode manufacturing and quality, ognizing that plating distribution across the see Reference 3. surface of a printed wiring board panel and Each anode ball was cut with a diamond saw from the surface of the panel through the holes and given a light etch to reveal. Figure 9 shows will vary due to resistances. By mitigating the an SEM of each of those. Clearly there is a dis- effects of these resistances, plating distribution tinctive difference among the grain structures is improved.

The Importance of Quality Anodes-Care and Maintenance It is surprising how little attention is paid to the quality and maintenance of the copper anodes. The grain structure is the most critical characteristic of copper anodes. This structure is predicated on the manufacturing process of the anodes, which in turn determines the grain structure of the copper. Fine grained size of the copper is the preferred orientation. The uniformity of grain size and the dispersement of the phosphorous along the grain boundaries will Figure 8: External view of three anodes from aid in the orderly dissolution of the copper. three different manufacturers.

Figure 9: Manufacturer 1 (left), Manufacturer 2 (middle) and Manufacturer 3 (right).

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Optimization of Acid Copper Electrodeposition Processes continues and phosphorous dispersion (shown as the dark and placement and proper selection of organic areas). As one views each of the structures, the plating additives and the electrolyte (inorganic differences are remarkable. chemistry). PCB The anodes from Manufacturer 1 show large and uneven grain boundaries. In addition, the References phosphorous is unevenly distributed. This leads 1. D.R.Gabe, Trans IMF 2003, 81, 7. Ward. to high organic additive consumption, anode 2. Yung, E.K. and Romankiw, L., “Fundamen- sludge and plating roughness. The anodes from tal Study of Acid Copper Through-hole Electro- Manufacturer 2 and 3 are the ideal quality re- plating Process,” Symposium on Electrodeposi- quired for PCB plating for high-aspect ratio tion Technology, The Electrochemical Society, holes. Pennington, New Jersey, pages 612–635. 3. Chuck Walker and Steve Doyle, Electro- Summary plating: The Importance of Copper Anodes, While electroplating PCBs with aspect ra- Finishing World. tios greater that 12:1 is probably best accomplished with periodic pulse reverse plating, direct current plating will produce high-quality Michael Carano is with circuit boards with aspect ratios up to 12:1. RBP Chemical Technology. This requires that several parameters be opti- To contact the author, mized for throwing power and plating distri- click here. bution. These parameters include plating cell design, high quality copper anodes, solution agitation with use of eductors, anode length

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Electroplating Through-Holes with Different Geometry: A Novel and High- Productivity Process

by Elie Najjar, Leon Barstad, This paper describes a novel copper through- Jayaraju Nagarajan, Marc Lin, hole fill electroplating process designed for Maria Rzeznik and Mark Lefebvre use with insoluble anodes and direct current Dow Electronic Materials (DC) rectification. The copper through-hole fill chemistry is formulated to operate over a broad range of operating conditions, and offers end- Abstract users outstanding production flexibility in ei- MicrofillTM through-hole fill (THF) electro- ther panel or pattern plate operating mode. lytic copper is a new process designed to offer The paper addresses electrolytic copper outstanding through-hole fill, particularly for through-hole filling performance for a variety substrates intended for use as core layers in of substrate thicknesses and hole diameters. build–up applications, producing planar, solid The impact of the hole formation method and copper plugs in high-volume production plat- hole quality on filling ratio and void formation ing equipment. This technology is intended to will be discussed. In this work, production scale replace resin or paste plugging, and offers many tests were performed on 100 μm and 200 μm advantages, including improved reliability, thick substrates. The impacts of varying current higher electrical and thermal conductivity, in- density and solution flow on hole filling were creased productivity and reduced process costs. examined. With optimized deposition condi-

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Electroplating Through-Holes with Different Geometry continues tions, including on-line additive analysis, void- source of cupric ions), sulfuric acid (for solution free, highly planar through-hole filling and ex- conductivity) and chloride ion (as a co-sup- cellent bottom-up blind microvia filling with pressor). Of these components, sulfuric acid, low surface copper deposition thickness were typically at concentrations below 60 g/L, has demonstrated. the most significant effect on achieving good through-hole filling. A plating solution with Introduction elevated acid concentration leads to conformal Portability of consumer electronics has be- plating causing poor filling performance. come the primary driver for the ever-increasing circuit density of today’s printed circuit designs. Organic Components Based on the small dimensions of these devices, Acid copper sulfate system operated with- through-hole and blind via diameters are typi- out additives typically yield deposits of poor cally in the 75–150 µm range. Performance im- physical properties. Organic additives, typical- provement and process cost reduction make ly consisting of materials described as suppres- through-hole filling technology with copper sors, brighteners, and levelers, are therefore an excellent approach, rather than the conven- used to further refine deposit characteristics. tional plated through-hole. Via fill plating systems were not designed for Prior to the development of electrolytic through-hole filling applications. The organic copper through-hole filling, substrates for such components and their respective concentra- applications were electroplated with a conven- tions used to achieve bottom-up filling in blind tional through-hole process, then plugged with microvias are less effective for initiating fill in an epoxy material. Following these steps, addi- the very different geometry of a through-hole. tional planarization, re-metallization and elec- Therefore, a novel organic package was devel- trolytic copper capping processes were required oped specifically to favor the fill mode essen- before the build-up process steps could begin. tial to completely plug the through-hole with Use of electrolytic copper through-hole fill- copper. While an accelerated bottom-up fill ing eliminates several of these manufacturing mechanism is the critical aspect of blind mi- steps and offers a number of additional advan- crovia filling, through-hole filling requires ini- tages over the conventional build-up process by tial creation of a “butterfly” structure, formed enhancing the thermal and electrical conduc- by rapid copper deposition at the center of the tivity of the interconnections, and by reducing holes. This change in geometry is the critical overall costs. first step in achieving good copper through- hole filling. Inorganic Components The vast majority of through-hole fill electroplating baths are based on acid sulfate elec- trolytes, containing copper sulfate (the primary

Figure 1: Through-hole plug: conventional vs. current technology. Figure 2: Conformal plating of a through-hole.

24 The PCB Magazine • May 2015 feature

Electroplating Through-Holes with Different Geometry continues

Figure 3: Butterfly structure leading to subsequent via formation.

In order to appreciate all the aspects of the “single chemistry does it all” challenge, it is use- ful to discuss the effects of different through- hole geometries on through-holes fill.

Through-Hole Shape Currently, blind vias, buried vias and though-holes are used in the fabrication of high-density interconnect designs. Mechanical drilling has been the conventional way to form holes and this process is still the basis for most printed circuit board manufacturing. In addition, through-holes can be formed using either one-sided (OSLTH) or double-sided Figure 4: Mechanically drilled hole (100 μm x laser drilling (DSLTH). The shape of such holes 100 μm). is not perfectly cylindrical, as shown in Figure 5 below. The tapered hole-wall profiles make such holes somewhat easier to fill with copper than the more cylindrical mechanically drilled In theory, once the transition from cylin- holes. As a result of this difference, mechani- drical through-hole to double blind via has cally drilled holes may show a highest tendency taken place, a microvia fill system could be for seam void formation than double-sided laser used to complete the filling. Although it is pos- drilled through-holes. sible to use two different chemistries to achieve One-sided laser drilled holes (OSLTH) can through-hole fill, most printed wiring board be prone to voiding due to the drilling process, manufacturers have chosen to adopt a single which may cause excessive differences in hole di- chemistry/one step approach to through-hole ameter between the top and bottom of the panel. fill, regardless of the hole shape. However, man- Although panel thickness also has a major ufacturers may be forced to modify their ap- impact on the ability to achieve good fill with- proach as new challenges in hole size, planarity out voiding, overall DSLTH are easier to fill and and void requirements emerge. less prone to void formation.

26 The PCB Magazine • May 2015 feature

Electroplating Through-Holes with Different Geometry continues

Figure 5: Double-sided and one-sided laser drilled holes.

Figure 6: Double-sided laser drilled through-hole in 100 µm (left) and 200 µm (right) thick panels.

Chemistry Development filling. Even with the use of a strong leveler, To develop a new DC-based plating bath the leveler concentration has a huge impact on that can achieve good hole filling performance hole-filling capabilities and on the deposit ap- with minimal voiding, development efforts pearance and surface morphology (roughness were directed towards the interaction of bright- and resistance to formation of nodules). ener and leveler additives. Levelers are prefer- For instance, a low leveler concentration entially adsorbed at areas of higher curvature will lead to a lack of inhibition at the entrance such as the entrance of the hole, where mass of the holes, with the result being excessive transfer is enhanced, and thus filling behavior plating rate at the knees, leading to formation is strongly influenced by convection. of seam voids. An excessive leveler concentra- The competitive adsorption between bright- tion will negate the ability to selectively inhibit eners and levelers result in a concentration only those areas with high curvature, resulting gradient along the hole wall, with the leveler- in a conformal deposit and increased risk of rich corner effectively inhibited relative to the nodule formation. brightener rich center, resulting in the non- Electrochemical studies confirm that the uniform plating rate required for through-hole adsorption of leveler on the hole openings and

May 2015 • The PCB Magazine 27 feature

Electroplating Through-Holes with Different Geometry continues

Table 1: Filling performance as a function of additive concentration.

Figure 7: Optimized THF copper chemistry. outer parts of the through-hole walls are mass transfer dependent. Furthermore, both electrochemical and plating studies indicate that the in- hibiting strength of levelers are also dependant on Figure 8: Side view of jet impingement plating the leveler concentrations, as shown in Table 1. cell. After extensive research and development efforts, a well balanced additive package was developed to achieve the desired through-hole filling performance. Through-Hole Fill Performance Matrix This process was developed to work with Through-hole fill plating performance, solution jet impingement and insoluble an- like blind microvia filling, may be character- odes in both vertical batch mode and vertical ized by the calculation of the dimple depth in-line and horizontal conveyorized plating or bump height. Dimple depth is the most equipment. A wide variety of equipment de- commonly used metric to quantify both sign features that further enhance though-hole through-hole and via plating performance. fill plating performance may be incorporated. Depending on customer and application, These include the use of engineered fluid deliv- void area (Figure 9) may also need to be deter- ery devices such as eductors or nozzles designed mined. Customer specifications for void area to create optimized flow impingement on panel are typically expressed as % void, that is, void surfaces. area/hole area.

28 The PCB Magazine • May 2015 feature

Electroplating Through-Holes with Different Geometry continues

Figure 9: Dimple and void measurements.

Impact of Substrate Condition and Pretreatment The thickness, coverage and surface condition of the electroless copper metallization layer applied to the panel prior to the through-hole filling process has a profound impact on through-hole filling and plating capability. Discontinuous or overly thin electroless copper deposits will not electroplate as reliably as thicker, more uniform deposits. Oxidation of elec- Figure 10: Plating performance as a function of electroless troless copper can also adversely affect type and quality. filling performance. Internal data has shown that, in particular, aged electroless copper has an unfavorable impact on process consistency. Proper control of pre- Impact of Process Agitation and treatment processes also plays an important role Current Density on Hole Filling in achieving good hole filling. A typical process Fluid delivery and flow agitation have a sig- sequence uses acid cleaner and acid dip steps nificant impact on hole filling performance, to ensure that copper surfaces are completely particularly in the presence of a leveler compo- wetted and free of contamination prior to the nents. To understand the effect of agitation on subsequent copper plating step. hole filling, solution flow rate was varied in a

30 The PCB Magazine • May 2015 feature

Electroplating Through-Holes with Different Geometry continues

Table 2: Plating performance as a function of flow conditions. series of plating experiments performed in ver- good hole filling performance. It is imperative tical continuous pilot plant plating equipment that agitation parameters be carefully chosen to at Applied Equipment Limited (AEL) and NanYa match plating cell design and application. It is (Taiwan). also important to note the positive value of cur- The effects of both these parameters on fill- rent density ramp accompanied by flow ramp ing performance were significant, with the re- on reducing void formation. sults showing that the impact of solution flow A similar test was then conducted in which rate is the strongest. While lower levels of so- current density (CD) was varied. lution flow rates were found to improve hole The intention of this test was to demon- filling performance; depending on application, strate the broad capability of the process that this improvement sometimes came at the price has been developed. Table 3 shows the effect of of seam void formation. A flow ramp scheme, current density on through-hole filling perfor- accompanied by good wetting during pre-clean- mance. Consistent filling was achieved across a ing, reduced void formation while maintaining wide range of current density.

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Electroplating Through-Holes with Different Geometry continues

Table 3: Plating performance as a function of CD.

Table 4: Pattern plate through-hole fill.

Process Performance pearance. These targets must be achieved and Applications using the finalized Microfill maintained as the bath is cycled. To evaluate THF bath require excellent through-hole filling aged bath performance, test panels were pro- performance combined with good surface ap- cessed in a vertical batch pilot scale plating

34 The PCB Magazine • May 2015 feature

Electroplating Through-Holes with Different Geometry continues

Figure 11: Through-hole dimple depth as a function of bath age and panel thickness in vertical batch plating cell.

Table 5: Deep holes filled using the Microfill THF bath.

cell at bath ages from 0 to more than 100A.h/L. crofill THF process. This test was performed Consistent dimple depth of less than 10 μm was at 2.5 ASD with a copper surface deposition maintained with board thickness of 100 μm target of 25 μm. All holes were fully filled with and 200 μm. copper with an acceptable dimple depth of This process may be used in either panel or < 12.0 μm. pattern plate processes. Table 4 demonstrates Table 6 also demonstrates that the bath can the capability of the process to fill through- also be utilized for the metallization of blind holes when used in a pattern plate mode. microvia (BMV) with surface copper thickness Table 5 shows results of tests performed of less than 15 μm. Bump formation on top of in AEL equipment of deep through-hole fill- the blind microvias can be minimized by modi- ing, which reveal the capability of the Mi- fying such plating parameters as solution agita-

36 The PCB Magazine • May 2015 feature

Electroplating Through-Holes with Different Geometry continues

Table 6: BMV performance of Microfill THF bath.

Table 7: Filled through-hole interconnect reliability.

Figure 12: Deposit physical properties at 2 ASD.

38 The PCB Magazine • May 2015 U

For more information please contact [email protected] call (415) 508-5826 or check out our website at www.ucamco.com feature

Electroplating Through-Holes with Different Geometry continues tion and current density. Based on these results, creasing overall operational efficiency and reli- this system could be utilized for BMV plating ability. PCB for flip chip application. References Process Reliability and Physical Properties 1. W.P. Dow, M.Y. Yen, M.J. Lefebvre, Studies To establish through-hole fill reliability, of Microvia Filling Mechanism and a Novel Cu cross sections were prepared after solder float- Plating Formula, IMPACT 2007. ing six times at 288°C per IPC procedure. The 2. Wei-Ping Dow, et al., Journal of the Elec- holes were then inspected. No cracks in the cop- trochemical Society, 2008, 155, (12) pp. D750- per deposit or other defects were detected. D757. The Microfill THF bath provides consistent 3. U. Landau, “Copper Metallization of deposit physical properties from a bath cycled Semiconductor Interconnects—Issues and Pros- up to 100 A.hr/L. Tensile strengths above 35 pects,” Proceedings, Electrochemical Society kpsi and elongations in the range of 20–30% (2001), 2000–26 (Chemical Mechanical Pla- were measured for deposits plated over a range narization IV), 231–252. of bath ages. 4. T. P. Moffat, D. Wheeler, and D. Josell, Journal of The Electrochemical Society, 2004, Summary 151(4), C262-C271. A novel DC through-hole filling process 5. J. P. Healy, D. Pletcher, and T.H. Bailey, was formulated for high-volume HDI and sub- Journal of Electroanalytical Chemistry, 1998, strate core layer metallization production. The 338. process yields high quality results over a wide 6. M. Lefebvre, L. Barstad, L. Gomez, New current density range. The process has already Copper Electroplating Technology for Through- been commercialized at a number of customers Hole Filling Hole Plating, IMPACT 2011. and it is anticipated that there will be substan- 7. M. Lefebvre, E. Najjar, L. Barstad, L. Go- tial future growth in adoption of this technol- mez, Next Generation Electroplating Process for ogy to fill through-holes. This ‘single chemis- HDI Microvia Filling and Through-hole Plating, try does it all,’ in combination with optimized IMPACT 2008. plating conditions and plating equipment, is 8. M. Lefebvre, E. Najjar, L. Barstad, High compatible with all though-hole geometries. Speed Direct Current Copper Electroplating The plated copper has excellent physical and Technology IMPACT 2011. mechanical properties, with a bright and lev- eled surface. This formulation is intended to be used with either vertical or horizontal in- line jet impingement equipment in both panel Elie Najjar is senior R&D manager at Enthone and pattern modes. All organic additives can and was formerly a senior electrochemist be monitored and controlled by conventional with Dow Chemical Company. CVS analysis techniques. Moreover, Dow Elec- tronic Materials is currently working with ECI Leon Barstad is lead electroplate engineer at Technology and AEL to introduce ECI’s online Dow Chemical Company. chemical monitoring systems. This will provide analysis capabilities for front-end plating ap- Jayaraju Nagarajan is senior electrochemist at plications in high-volume manufacturing fabs. Dow Chemical Company. The analytical techniques incorporated in the on-line analysis will provide complete chemi- Marc Lin is market manager at Dow Chemi- cal metrology solutions to meet the stringent cal Company. specifications necessary for such applications. This approach allows for reduction of chemi- Maria Rzeznik and Mark Lefebvre are R&D cal reagent consumption, drastically decreases managers at Dow Chemical Company. maintenance and waste generation, while in-

40 The PCB Magazine • May 2015

Electronics Industry News Market Highlights

Optical Components Market Growth Gartner Reveals Vertical Industry Trends Picking up Again in 2015 in SEA’s Thriving Markets LightCounting’s analysis shows that optical com- “Some might argue that given recent political, fi- ponents market has been growing at 8–12% per nancial and climate challenges, Southeast Asia is a year on average over the past five years, but slowed risky proposition,” said Venecia Liu, research vice during the second half of 2014. Recent reports president at Gartner. “However, Gartner believes from leading suppliers indicate that market growth that Southeast Asia’s economic development and picked up in Q1 2015, and LightCounting expects growing consumer demand mean that its growth that the market will reach a new record in Q2 2015. potential outweighs the risk.”

Smart Grid Sensors Market to Hit Flexible Display Market to Hit $30B by 2025 $350M in 2021 In the newly published “Flexible, Curved, and Bend- The market for smart grid sensors is set to rapidly able Display Technologies and Market Forecast expand in the coming decade, with revenues grow- 2015 Report,” (Second Edition), Touch Display Re- ing nearly ten-fold, from 2014–2021, according to search analyzed more than 10 display technologies IHS Inc. Based on information in a new study from and more than 14 applications of flexible displays, IHS Technology, the market for smart grid sensors and the report shows how the flexible display mar- is centered in North America. ket is accelerating.

State of U.S. Manufacturing After Smart Wearable Healthcare Devices the Recession Market to See Significant Growth Since the economic recovery started in 2009, the The Technavio report emphasizes the increased use U.S. manufacturing sector generally maintained a of smart wearable devices for tele-home healthcare. 12% share of GDP over the five years ending in Monitoring many patients in hospitals can be a te- 2013. The sector’s performance was impressive dious process because of the lack of adequate re- when compared with other major advanced coun- sources. Smart wearable devices enhance treatment tries that experienced similar declines and early re- and monitoring processes by saving time and re- coveries in manufacturing production. ducing healthcare costs.

Flexible Batteries Market Attracts IoT Data to Exceed 1.6ZB in 2020 New Investments A new report from ABI Research estimates that the After years of slow progress from small compa- volume of data captured by IoT-connected devices nies, flexible batteries now have the attention of exceeded 200 exabytes in 2014. The annual total big brands such as Apple, Samsung, LG Chemical, is forecast to grow seven-fold by the decade’s end, Nokia and STMicroelectronics, who are set to drive surpassing 1,600 exabytes—or 1.6 zettabytes—in the flexible battery market from US$ 6.9 million in 2020. 2015 to over US$ 400 million in 2025 according to IDTechEx. Tech Transfer Provided $1.8T to US Economy The report, “The Economic Contribution of Uni- Next-Gen Smart Lighting Systems versity/Non-profit Inventions in the United States: Revenues to Hit $1B by 2020 1996–2013,” estimates that, during this 18-year In a new report, “Smart Lighting Market Oppor- time period, academia-industry patent licensing tunities: Smart Bulbs and the Rise of Local Light- bolstered U.S. gross industry output by up to $1.18 ing Intelligence,” NanoMarkets concludes that the trillion, U.S. gross domestic product (GDP) by up to market for these new systems will reach just over $518 billion, and supported up to 3,824,000 U.S. $1 billion by 2020. jobs.

42 The PCB Magazine • May 2015 feature

ENEPIG: The Plating Process by George Milad oxidation-reduction chemical reaction, without Uyemura International Corporation the application of an external electrical potential. Reducing agents, such as sodium hypo- phosphite or sodium formate, react at catalytic Electroless nickel/electroless palladium/im- surfaces to release electrons, which immediately mersion gold (ENEPIG) is sometimes referred reduce the positively charged metal ions (e.g., to as the universal finish, because of the versa- nickel ions in ENIG and ENEPIG and palladium tility of its applications. It is a multifunctional ions in ENEPIG), promoting their deposition surface finish, applicable to soldering and wire onto the PWB. bonding (gold, aluminum, copper and palladi- This type of reaction is described as autocat- um clad copper). In addition, it is also suitable alytic, as the deposition process will continue as the mating surface for soft membrane and even after the substrate is completely covered steel dome contacts, low insertion force (LIF) by a continuous layer of the plated deposit. The and zero insertion force (ZIF) edge connectors, deposit thickness will therefore continue to rise and for press-fit applications. ENEPIG is formed in the presence of source metal ions and a reduc- by the sequential deposition of electroless Ni ing agent, until the board is removed from the (120–240 µin) followed by 2–12 µin of electroplating bath. The thickness of plated deposits less Pd with an immersion gold flash (1–2 µin) will vary depending on the bath temperature, on top. chemical parameters (such as solution pH) and the amount of time spent in the plating bath. Chemical Definitions Immersion Process: This chemical process uses Electroless Process: This chemical process a chemical displacement reaction to deposit a promotes sustained deposition of a metal or layer of a second metal onto a base metal sur- metal alloy onto the PWB surface through an face. In this reaction, the base metal dissolves,

44 The PCB Magazine • May 2015 Phone [775] 885-9959 • www.taiyo-america.com • [email protected] feature enepig: the plating process continues releasing the electrons that reduce the positively Nickel: 3–6 µm [118.1–236.2 µin] at ± 4 sig- charged ions of the second metal present in so- ma (standard deviations) from the mean. lution. Driven by the electrochemical potential Palladium: 0.05–0.15 µm [2–12 µin] at ± 4 difference, the metal ions in solution (e.g., gold sigma (standard deviations) from the mean. ions in ENIG or ENEPIG process) are deposited Gold: Minimum thickness of 0.025 µm [1.2 µin] onto the surface of the board, simultaneously at - 4 sigma (standard deviations) below the mean. displacing ions of the surface metal into solution. All measurements to be taken on a nominal pad This type of reaction will continue as long as size of 1.5 mm x 1.5 mm [0.060 in x 0.060 in] or the base metal is available to supply electrons to equivalent area. the displacement reaction. ENEPIG has the advantage over ENIG of be- An amendment that sets an upper limit for ing a gold wire bondable surface. ENIG is not gold thickness for ENEPIG at 2.8 µin (0.7 µm) an ideal gold wire bonding surface because over is presently in final draft for peer review. The time the electroless nickel will diffuse through amendment was necessary because too many to the surface along the crystal boundaries of designers were specifying a much higher immer- the immersion gold and the wire would not sion gold value. The higher thickness involved stick. ENEPIG’s palladium layer is a diffusion increased dwell time in the gold bath, resulting barrier to the nickel, the gold remains unadul- in nickel corrosion under the palladium layer. terated and is bondable with gold thickness as low as 1.2 µin or ENEPIG Fabrication 0.03 microns. The copper surface coming A gold coating as thick Soldermask application to the ENEPIG line in most as 0.1–0.2 microns or 4–8 cases follows tin stripping and µin would open the wire involves“ cleaning and the application of soldermask. bonding operating window. roughening the copper Residual tin left on the surface Thicker gold is beyond the surface, the application will interfere with catalyza- capability of standard im- tion of the copper surface. mersion gold. If a thicker of a photoimageable Soldermask application in- gold is specified, then modi- mask, tack drying, volves cleaning and roughen- fied immersion gold, such as ing the copper surface, the ap- reduction-assisted immer- imaging, developing and plication of a photoimageable sion gold, would be the pre- curing. Attention to the mask, tack drying, imaging, ferred choice. details of processing developing and curing. Atten- The electroless palladium tion to the details of process- requires a reducing agent. The soldermask is paramount ing soldermask is paramount most commonly used reduc- to achieving the desired to achieving the desired EN- ing agent is sodium hypo- ENEPIG deposit. EPIG deposit. The proper ad- phosphite, which produces a hesion between the mask and phos-palladium deposit with the copper surface has to be 4–5% phosphorous in the de- achieved. After development posit. The presence of phospho- there should be no organic residues rous renders the palladium deposit amorphous left on the pad surfaces, and the side wall should (non-crystalline), making it the ideal diffusion” be straight with no signs of negative or positive barrier. Other reducing agents may produce a foot. This is particularly important if the design non-phos palladium, which tends to be crystal- includes soldermask defined pads. line in structure. Process Sequence The ENEPIG IPC-4556 Specification 2013 1. Cleaner: The purpose of this step is to For ENEPIG thickness, IPC-4556 states: clean the copper surface in preparation for pro-

46 The PCB Magazine • May 2015 feature enepig: the plating process continues cessing. The cleaner removes oxides and light run at high temperatures and extended dwell surface contaminants, and ensures that the times to achieve the required deposit thickness. surface will be in a condition allowing it to be It is therefore important to ensure that compat- uniformly micro-etched. Vendor specifications ible PWB substrate and solder mask materials for temperature, dwell time, agita- are used. Vendor specifications for tion and bath chemical control temperature, dwell time, agita- should be followed. tion and bath chemical control The catalyst lowers should be followed. 2. Micro-etch: This step produces a surface that may the activation“ energy 5. Electroless Palladi- be uniformly catalyzed and um: This bath deposits the plated with good deposit ad- for nickel deposition desired thickness of electro- hesion by removing some and allows plating to less palladium on the freshly copper from the surface. A deposited nickel surface. It is variety of different etchant initiate on the copper mainly composed of a source types may be used (e.g., sodi- surface. Examples of of palladium metal ion and a um persulfate, peroxide/sul- reducing agent. In addition, it furic). Vendor specifications metal catalysts include has proprietary stabilizers, sur- for temperature, dwell time, palladium and ruthenium factants and chelating agents. agitation and bath chemical The solution requires replen- control should be followed. (deposited by an ishment of all of its compo- immersion reaction with nents to maintain its activity. 3. Catalyst: The step de- Vendor specifications for tem- posits a material that is cata- the copper surface) perature, bath life, dwell time, lytic to electroless nickel plat- agitation and bath chemical ing on the copper surface. The control should be adhered to. catalyst lowers the activation energy for nickel deposition and allows 6. Immersion Gold: The purpose of plating to initiate on the copper surface. Ex- this step is to deposit a thin, continuous layer of amples of metal catalysts include palladium” immersion gold. and ruthenium (deposited by an immersion reaction with the copper surface). Vendor specifications for temperature, dwell time, agitation and bath chemical control should be followed.

4. Electroless Nickel: The purpose of this bath is to deposit the required thickness This is a displacement reaction. Note: As a of electroless nickel on the catalyzed copper result of their respective position in the electro- surface. The nickel thickness should be ade- motive series, the exchange rate of gold with quate to cover the copper with a substantially the palladium substrate is not as efficient as pore-free coating, to create a diffusion barrier gold with the nickel substrate. to copper migration, and also serve as a sol- The gold protects the underlying electroless derable surface, depending on the intended palladium layer from reacting with the ambient application. environment and also serves as a contact sur- The nickel bath has a relatively high depo- face, depending on the intended application. sition rate and its active chemical components This bath runs at relatively high temperatures must be maintained in balance on a continuous and dwell times. Vendor specifications for tem- basis, by addition of appropriate replenishment perature, dwell time, agitation, bath life and components. Electroless nickel baths typically bath chemical control should be followed.

48 The PCB Magazine • May 2015 May 13–14 October 13–15 IPC Technical Education IPC Europe Forum: Innovation for Reliability Fort Worth, TX, USA Essen, Germany Professional development courses for engineering staff Practical applications for meeting reliability and managers: challenges like tin whiskers, with special focus on • DFX-Design For Excellence (DFM, DFA, DFT and more) military-aerospace and automotive sectors • Best Practices in Fabrication • Advanced Troubleshooting October 26–27 • SMT Problem Solving IPC Technical Education June 9 Minneapolis, MN, USA ITI & IPC Conference on Emerging & Critical Professional development courses for engineering staff and managers: Environmental Product Requirements • DFX-Design For Excellence (DFM, DFA, DFT and more) Fort Lee, NJ, USA • Best Practices in Fabrication • Advanced Troubleshooting June 9–10 • SMT Problem Solving IPC Technical Education October 28–29 Chicago, IL, USA IPC Flexible Circuits-HDI Conference Professional development courses for engineering staff and managers: Minneapolis, MN, USA • DFX-Design For Excellence (DFM, DFA, DFT and more) Presentations will address Flex and HDI challenges in • Best Practices in Fabrication methodology, materials, and technology. • Advanced Troubleshooting • SMT Problem Solving November 2–6 IPC EMS Program Management Training June 10 and Certification ITI & IPC Conference on Emerging & Critical Chicago, IL, USA Environmental Product Requirements Des Plaines, IL, USA November 4 PCB Carolina 2015 June 12 Raleigh, NC, USA ITI & IPC Conference on Emerging & Critical Environmental Product Requirements December 2–3 Milpitas, CA, USA (San Jose area) IPC Technical Education September 27–October 1 Raleigh, NC, USA Professional development courses for engineering staff IPC Fall Standards Development Committee and managers: Meetings • DFX-Design For Excellence (DFM, DFA, DFT and more) Rosemont, IL, USA • Best Practices in Fabrication Co-located with SMTA International • Advanced Troubleshooting • SMT Problem Solving September 28 December 2–4 IPC EMS Management Meeting International Printed Circuit and APEX South Rosemont, IL, USA China Fair (HKPCA & IPC Show) October 13 Shenzhen, China IPC Conference on Government Regulation Essen, Germany Discussion with international experts on regulatory issues

Questions? Contact IPC registration staff at [email protected] or +1 847-597-2861 feature enepig: the plating process continues

7. Rinsing: These steps remove residual good understanding of how the process works process chemicals from the PWB surface after and the critical parameters that must be main- each chemical processing step. This may be tained. The ENEPIG line has little tolerance achieved in either a single step or with multiple for deviations, particularly to extending the rinses. In some instances, pre-dip and/or post- bath life of any of the process steps. Shops that dip process steps may also be required for op- have good engineering and documentation of timum process performance. Vendor specifica- the manufacturing process, coupled with a tions for temperature, dwell time, agitation and dedicated, experienced ENEPIG operator that turn-over rate should be followed. is backed by a capable analytical laboratory, run defect-free ENEPIG day in and day out, to 8. Drying: Ensure the boards are complete- a consistent product that meets customer re- ly dry may be achieved by use of either in-line quirements. PCB vertical, or off-line horizontal drying. Off-line horizontal drying should be preceded by a horizontal rinsing step and should be dedicated to George Milad is the national the boards from the ENIG/ENEPIG processes. accounts manager of technology The time and temperature should be optimized at Uyemura International to suit the type of product. Corporation. To reach the author, click here. The ENEPIG line is the most complex chemical process in a board shop. It requires a

NEW Multi-Part Interview! & Space Museum (home of the Spruce Goose), located in the Oregon community A Conversation (and Day) of McMinnville. Their conversation ebbed and flowed with Joe Fjelstad between a wide variety of topics, from the electronics I-Connect007 Publisher Barry Matties and industry, to political shenani- industry veteran Joe Fjelstad, CEO and founder gans and the “war against of Verdant Electronics, met recently to spend a failure.” day together enjoying the Evergreen Aviation Click here to view part 1.

50 The PCB Magazine • May 2015 CP 6080 LOW COST DIGITAL INK JET PRINTER

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Atotech’s Uwe Hauf’s View of the Global Mass Design Acquires Electropac Electronics Manufacturing Market “Like Mass Design, Electropac has served com- Uwe Hauf, VP of electronics for Atotech, and I-Con- mercial, medical, military and aerospace industries nect007 Publisher Barry Matties sat down at CPCA with custom design and manufacturing as well as 2015 for an illuminating discussion of the global large-volume production. The company’s key peo- market—what’s happening now, what is going to ple, expertise, product mix and markets mesh per- happen tomorrow, and a few things that won’t fectly with our corporate environment,” said Tony happen for at least 10 years, according to Hauf. Bourassa, president of Mass Design, in making the announcement. Isola Launches Low-loss Laminate for 100 GB Ethernet Apps Amitron Earns UL Certification for I-Connect007 Technical Editor Pete Starkey and Aismalibar IMS Materials Isola’s Fred Hickman, senior director of high-speed Amitron Corporation has received their UL listing digital products, spent time at IPC APEX EXPO for Aismalibar’s full range of insulated metal sub- 2015 talking about Isola’s recent launch of a low- strate materials. The certification allows Amitron loss, low-skew laminate prepreg. Hickman explains to UL stamp their products using the entire line that the new material, Chronon, will be one of the of Aismalibar materials which includes ALCUP-G enablers of 100GB Ethernet applications. 1.3w, ALCUP 1.8w, HTC 2.2w, HTC 3.2w, HTC Ul- trathin and Flextherm. Hitachi Chemical America Hosted HDP’s Member Meeting Royal Circuits Acquires Second Maskless Hitachi Chemical America hosted HDP User Group LDI Machine International Inc.’s first 2015 member meeting at Milan Shah, president and owner of Royal Cir- its Plumwood House Research Center, located on cuits Solutions announced that his company has the campus of the University of California, Irvine. recently acquired their second Maskless Lithog- raphy direct imaging machine. Royal is one of Benefits of Soldering with the first PCB fabricators to own two of these Vacuum Profiles units. Requirements for void-free solder joints are con- tinuously increasing in the field of electronics Material Witness: Low-Flow Prepregs— manufacturing, bringing new challenges that are Taming the Beast! evolving on a daily basis due to the relentless in- In this installment of Material Witness, Chet Guiles troduction of new variants of so-called bottom- continues his discussion around low-flow pre- terminated components (BTCs). Connector geom- pregs, with good advice about how to actually use etries alone are not decisive—numerous pitfalls are these materials. of greater significance. atg Luther & Maelzer Launches Flying Candor Industries Becomes Approved Probe Tester for Substrates Vendor for Microsoft atg Luther & Maelzer has delivered the first flying Candor Industries, an advanced technology cir- probe system for substrate test to a major custom- cuit board fabricator based in Toronto, Ontario er in Korea. The S3 10 µm substrate tester is the announces their acceptance to the Microsoft Pre- first system of a new atg Luther & Maelzer product ferred Supplier Program. line.

52 The PCB Magazine • May 2015 Atotech – Specialty Chemicals Production Chemicals, Equipment, Services & Solutions

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Ad15_EL_Image_Collage_W203xH267.indd 1 27.04.2015 20:09:34 Interview The Importance of Harmonized Standards that Benefit All

I-Connect007 Technical Editor Pete Starkey Starkey: IPC and IEC are really recognized as the caught up with Amphenol’s Applications Engi- world’s standards authorities, but do you notice neer, Sean Keating, at IPC APEX EXPO in San that some of the standards are originating from Diego. Keating explains his company’s commit- Asia and taking some prominence? ment to proactive participation in the estab- lishment of standards, his personal experience Keating: Certainly not with anything we’re working on standards committees, and his view doing in Europe, but I cannot answer for the on the importance of harmonised global stan- whole group as we have facilities in more than dards. 40 countries, worldwide. IPC, without doubt, has the lion’s share of standards, which are im- Pete Starkey: It’s nice to see you here at IPC APEX. posed on us by our major customers. As a design I understand Amphenol is strongly interested in and manufacturing facility we get standards im- standards and that you are personally active on posed on us as well as what we pass onto our some committees. Start by telling us about that. subcontractors. Virtually all of our major customers now have IPC standards of one type or Sean Keating: Amphenol another noted on their drawings. I’ve been with UK is very proactive in a Amphenol for 26 years and for the last 10–12 number of the standards, years this has grown from occasionally seeing in particular the certifi- an IPC standard called out to the point now cation standards. I have where nearly every single callout references an been working closely with IPC standard. IPC for about six or seven years now. My secondary Starkey: Provided that there is some international reason for being here is cooperation and our colleagues in Asia are pre- that this is a fantastic forum for problem solv- pared to recognize Western standards and cooper- ing. Any problems that have cropped up over ate with them, there is worldwide harmony. the weeks or months prior to the show can often be resolved using the immense technologi- Keating: Absolutely, and with Amphenol being cal think tank that’s here on the show floor, in a global company, we actually help train and the meetings, or even in the bar! facilitate at our India and China locations, so I’m on nine committees right now, from low that within Amphenol worldwide, we’re work- pressure overmoulding to electronics in space, ing to the same standard. And that harmony is and I would say we’re probably working 10+ absolutely imperative. It also means that when hours a day. It’s a busy week for a number of we talk to them, when we look at them as low the standards; much of my focus is on the IPC/ cost manufacturers, we can talk at exactly the WHMAA-620 cable and harness training com- same level and about the same things. So it re- mittee, which is meeting on Thursday to dis- ally has been helpful. cuss training. We are looking at having a more robust practical course that will be certifiable. Starkey: Sean, thanks very much for your time. This will mean that when you certify to that standard you have demonstrated the skills and Keating: Thank you, Pete. PCB proven ability to actually build a harness—not just inspect it. Perhaps, depending on how the committee decides, there will be different levels Interested in participating in an interview of harness ability or skill, but we will have to for The PCB Magazine? Click here for more wait and see on that one! information!

54 The PCB Magazine • May 2015 column point of view Best Practices 101: Part 7

by Steve Williams Steve Williams Consulting LLC

Management by Walking Around this, and that is “gemba.” Roughly translated Tom Peters, author of the “Excellence” series as “the real place,” gemba means getting off of books and one of my favorite management your butt and going to see where the work is visionaries, coined the phrase MBWA (Man- actually being done. Like many Lean buzz- agement by Walking Around). This is another words such as kaizen, gemba has transitioned concept that seems so obvious, but how many from obscure to ubiquitous across our indus- of us actually do this? This is a rhetorical ques- try. I love gemba, but like anything worth- tion, of course, but really, how often do we go while, you get out of it what you put into it. out on the shop floor and just observe what is Gemba demands a few things from the user to going on? I don’t mean tracking down orders be successful. and making sure people are working, but more First, it requires a deep curiosity to know along the lines of, how does the facility look? what is really going on in your organization. Do the workers look happy? Are we working Not what you think is going on, or what you smart or overcompensating by working hard? heard is going on, but what is actually going on. What would I think if I were the customer? You Next, gemba demands a skill set that includes can’t answer these questions sitting in your of- the ability to actively observe and understand fice! the work that’s being done. While this may seem obvious, doing a drive-by surface observa- Gemba tion won’t accomplish anything, and may actu- Peters was on to something with his MBWA; ally do some damage by providing a false sense in fact, the Japanese have a similar term for of process well-being. The last demand is per-

56 The PCB Magazine • May 2015 For ICT infrastructure equipment Low transmission loss multi-layer circuit board materials

industrial.panasonic.com/em point of view

Best Practices 101, Part 7 continues haps the most important: an inherent respect inventory, etc. It is important to limit the focus for the people actually doing the work. These because if you look for everything, you will ac- are your process experts that have the practi- complish nothing! cal experience and tribal knowledge of the pro- Instituting regular gemba walks into the cul- cess. Gemba walks need to be approached from ture will consistently demonstrate to employees a place of mutual respect and overriding desire a leadership commitment, alignment and sup- to make things better, faster, cheaper, easier, etc. port of the continuous improvement process. Gemba means going to where the work is being There are a couple of keys to a successful gem- done and engaging the people directly, not as- ba walk, such as active and attentive listening, suming you have solved all the problems from sharing what you learned during the gemba your office. walk with the entire organization, discussing with department leaders conditions observed, The Gemba Walk and following up/monitoring the process where The gemba walk provides company leaders, necessary. managers and supervisors a simple, easy means of supporting overall continuous improvement What the Gemba Walk is Not while directly engaging with the folks respon- A gemba walk is not an opportunity to point sible for the key business processes. The best ap- fingers and find fault in employees while they proach to a gemba walk is to start at the last pro- are being observed. It is not punitive; employ- cess and work upstream. Why? This will high- ees will shut down and not openly engage at the light how well your process is operating from a first whiff of this. It is not a time to be the policy high level in terms of pull vs. push, bottlenecks, police; internal audits or other tools are appro- inventory and other production control issues. priate for this. Finally, a gemba walk is not the Depending on the level of personnel participat- time to solve; it is a time of observation, input ing and/or circumstances, gemba walks can be and reflection. That does not mean disregarding daily, weekly or monthly. Another suggestion is operator ideas for improvements, but rather to to focus on a different aspect (theme) for each physically go and see what is really happening. gemba walk. For example, one day might focus Any ideas or complaints should be noted and on 5S in the facility; another may be on WIP followed-up with after the walk. Be mindful not

Figure 1.

58 The PCB Magazine • May 2015 point of view

Best Practices 101, Part 7 continues to “miss the forest because of the trees,” as the • Do customers and/or suppliers ever look saying goes. at the charts? • Do the charts have an overall effect on Visual Management operations? I am a big fan of meaningful visual management everywhere possible to keep employ- The key to any process improvement is to ees engaged, informed and foster a culture of question everything; do not just accept the ownership. Noticed my emphasis of the word status quo. Whether you manage by walking “meaningful” when talking about visual man- around, engage in gemba walks, or utilize some agement; what I mean by this is avoiding at all other method of going to where the work is costs a wallpaper strategy of posting gratuitous done, the key is to get out of your office and go charts, graphs, reports, etc., on walls to impress and see. PCB customers. The gemba walk provides a great opportunity to notice and question posted mea- Steve Williams is the president sures and charts and ask the following ques- of Steve Williams Consulting LLC tions: and the former strategic sourc- ing manager for Plexus Corp. • What is this chart telling me? He is the author of the books, • Who is responsible for updating them? Quality 101 Handbook and Sur- • Do the employees look at the charts? vival Is Not Mandatory: 10 Things Every CEO How often? Should Know About Lean. To read past col- • What value do the charts have for umns, or to contact Williams, click here. employees?

Video Interview Five Keys for Success in PCB Manufacturing

by Real Time with... IPC APEX EXPO 2015

All Flex VP of Sales and Mar- keting, Dave Becker, tells Kelly Dack, “It’s not about the technology.” He discusses the five core values that are part of the culture at All Click Flex, and as a final point, Becker explains how “cul- realtimewith.com ture beats strategy.” To View

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www.rogerscorp.com If you are unable to scan a VR code please visit our Support Team website at www.rogerscorp.com/coolspan Mil/Aero007 News Highlights

Zentech’s John Vaughan on the Zhen Ding Technology Holding Limited, Young Mil/Aero Sector: “It’s Headed Up” Poong Electronics Co. Ltd., Unimicron Technol- I-Connect007 Publisher Barry Matties and ogy Corp., and Samsung Electro-Mechanics are Zentech’s John Vaughan had a chance to discuss among the major suppliers of PCBs. The industry industry concerns within the mil/aero segment players are going for partnership and strategic at IPC APEX EXPO 2015. The two also shared alliances to deliver unique solutions and to meet thoughts on the space industry, and Vaughan the constantly changing industry demands of cus- detailed Zentech’s involvement with National tomers. Manufacturing Day, a nationwide effort focused on STEM (Science, Technology, Engineering and Battelle Unveils Breakthrough Math). Anti-Counterfeiting Detection for ICs “As counterfeiting continues to be a growing is- PNC Announces Latest Add-on sue for both suppliers and manufacturers, ensur- Qualification to MIL-PRF-31032 ing that all components are effectively and ac- PNC is proud to announce the latest add-on quali- curately verified for authenticity has become an fication of product testing to Military Performance increasingly time consuming and expensive task,” Specification MIL-PRF-31032, CAGE Code 66766. said Larry J. House, Cyber Technical Director, of The newest capabilities stem from PNC’s continu- Battelle. ous improvement of capital equipment. DARPA Programs Simultaneously Test Exception PCB Earns AS9100 Limits of Technology Certification Less than one week after releasing Breakthrough Exception PCB Solutions Ltd, one of Europe’s lead- Technologies for National Security, DARPA’s latest ing PCB producers, recently secured their AS9100 summary of the agency’s mission, accomplish- approval following a recent assessment by BSI ments and funding priorities for extending its leg- (March 2015). AS9100 is the internationally rec- acy of technological disruption, the agency today ognised quality management system specialised announced four major new programs—evidence to the aerospace industry. of DARPA’s commitment to pursuing high-risk/ high-reward research and making the impossible FTG Circuits Earns DoD Certification possible. for Flex PCB Firan Technology Group Corporation announced DARPA Shares Vision for the Future that its Circuits—Toronto facility has added flexible New biennial report describes the agency’s mis- and rigid-flex printed circuit boards to its qualifica- sion in the context of today’s fast-changing world, tion under Military Specification MIL-PRF-31032. and current and upcoming areas of focused in- This certification is in addition to the multiple ex- vestment isting certifications for a wide range of technologies already held by the facility. Boeing Boosts Imaging, Intelligence Services; Acquires 2d3 Sensing Key PCB Makers Strategize to Meet Boeing has acquired 2d3 Sensing, a wholly owned Industry Demands subsidiary of OMG plc specializing in motion im- The computer/peripheral application is expected agery processing of critical intelligence, surveil- to witness the highest growth followed by the lance and reconnaissance data generated from communication applications. Nippon Mektron, aerial platforms.

62 The PCB Magazine • May 2015 column karl’s tech talk Quick-Turn Circuit Board Shops

by Karl Dietz Karl Dietz Consulting LLC

Quick-turn circuit board shops specialize in Phototooling the speedy delivery of small lots or prototype The creation of a silver halide phototool in- boards. Thus, they value any processing tech- volves a number of time-consuming steps such nique and technologies that reduce the time as plotting, development, fixing, drying, and of the critical path between receiving the CAD equilibrating the phototool to the temperature data and shipping the finished boards. Some of and humidity of the working environment. the technologies that enable fast delivery are Equilibration is particularly time-consuming also suitable for mass production. The follow- (Figure 1). ing are some examples of quick-turn process- Some quick-turn shops have tried to short- ing. cut the equilibration step with limited success.

Figure 1: Humidity pre-conditioning times.

64 The PCB Magazine • May 2015 karl’s tech talk

Quick-Turn Circuit Board Shops continues

The target dimensions of the phototool features giving, this approach can be viable in reducing are those of a damp phototool. Typically, the overall processing time. dryer temperature of the processor is set lower than normal so that the film exits the proces- Digital Imaging sor just a little damp and relatively cool[1]. The Laser direct imaging, or other digital imag- film is measured within minutes after processing processes, has been first adopted by proto- ing and sent directly to the imaging area. A film type and quick-turn shops for the obvious rea- processed and used this way will slowly change son that they eliminate all phototool process- size over the next several hours while it is in ing steps. The other big advantage of LDI is its use, but when used quickly after processing and ability to scale the image (i.e., change the di- measuring, and if the tolerances are fairly for- mensions slightly, for best fit to image features

Figure 2: Schematic of a laser imaging tool.

66 The PCB Magazine • May 2015 karl’s tech talk

Quick-Turn Circuit Board Shops continues on another layer). Figure 2 shows the elements nerlayer print and etch. Some quick-turn shops of a typical laser imaging tool. have had success with a process flow whereby the multilayer bonder is applied to the innerlay- Direct Metallization Processes er copper surface before resist lamination, expo- Direct metallization processes allow cop- sure and development. In this process, the resist per plating in through-holes without having adheres to the multilayer coating, not to the to go the lengthy electroless copper process. copper. Dry film compatibility with this process Direct metallization process uses either carbon, sequence needs to be checked in terms of resist graphite, or palladium catalyst, or a conductive adhesion to such a surface, which is normally polymer to initiate copper electroplating on very good, and clean resist stripping needs to be the dielectric hole wall. These processes avoid established. This processing sequence takes the the use of problematic chemicals that are part bonder treatment out of the critical time path of the electroless copper formulation; they use for the board manufacture since the multilayer less water, typically have a smaller equipment treatment can be done off line, in advance of footprint, and use fewer processing steps, which the board manufacture. The bonder can also allow the quick-turn shop to reduce processing be beneficial as an anti-halation layer that pre- time. Table 1 compares a graphite-based direct vents unwanted reflection of UV light from the metallization process with the sequence of steps board surface into non-exposure areas. that make up the electroless copper process. Legend Print Multilayer Bonder Legend print is traditionally done by screen A multilayer bonder treatment (oxide or printing, which involves the time-consuming oxide alternative) is typically applied after in- screen preparation. In recent years, legend print-

Table 1: Comparison of direct metallization process sequence with electroless copper plating.

May 2015 • The PCB Magazine 67 karl’s tech talk

Quick-Turn Circuit Board Shops continues

Figure 3: Screen printing of legend ink. (source: Printar)

Figure 4: Ink-jetting of legend ink. (source: Printar)

ing by ink-jetting has become quite popular. Fig- ure 3 shows the screen printing process while Fig- Karl Dietz is president of Karl Dietz Consulting LLC. He of- ure 4 illustrates the simplicity of ink-jetting. PCB fers consulting services and References tutorials in the field of circuit 1. Private communication, Robert Seyfert. board & substrate fabrication 2. Printed Circuit Handbook, 6th Edition, technology. To view past col- Clyde F. Coombs, Jr. umns or to reach Dietz, click 3. “Shadow” process by OMGI (formerly here. Dietz may also be reached by phone at Electrochemicals). (001) 919-870-6230.

68 The PCB Magazine • May 2015

Top Ten Recent Highlights from PCB007

Multek CTO Excited about Reliability and Harmonization 1 the Challenges of the 3 of Global Standards at Fast-Moving Wearables Market Forefront of EIPC Efforts

I-Connect007 Publisher Barry Matties and recently- At IPC APEX EXPO 2015, I-Connect007 Technical appointed Multek CTO Dr. Joan Vrtis sat down at Editor Pete Starkey caught up with EIPC’s Michael IPC APEX EXPO to discuss the rapidly evolving wear- Weinhold and Alun Morgan, who were happy to ables market, especially for medical, and the myriad discuss both recent and ongoing focuses for EIPC. questions that must be addressed. Other topics in- Also touched on was the importance of the align- clude Multek’s contribution to the wearables indus- ment of global standardization processes, espe- try and what it sees as the main challenges to put- cially for Asia. ting their circuits into various applications. Are There Advantages to Raising a Unified Voice 4 Changing Your Registration 2 for an Advanced System? Manufacturing Economy I-Connect007 Publisher Barry Matties recently had The electronics manufacturing industry is an im- a conversation with DIS’s Tony Faraci at IPC APEX portant sector in the global economy, and John EXPO 2015, to learn more about their pinless Hasselmann, VP of Government Relations at IPC, registration system. What was most interesting is an advocate for policies that will help our indus- to Matties was the potential advantages a pinless try as well as the prosperity and welfare of billions system offers and why the process has not been of people. widely adopted.

70 The PCB Magazine • May May 2015 2015 Schmoll Keeping an Eye on ESI’s New Gemstone 5 the Future—and on LDI 8 Changing the Rules for Laser

In this interview, Thomas Kunz, who has been at I-Connect007 Publisher Barry Matties sat down the helm of Schmoll Maschinen as president since at CPCA 2015 with ESI’s Mike Jennings, who ex- 1993, discusses the company’s lengthy history in plained the company’s newest addition: Gem- mechanical engineering (more than 70 years), stone, an ESI-designed and manufactured laser current global scope, and what he sees as a steady system with 10,000 guaranteed hours, which is progression in directions that make the most sense poised to change the rules in flex and other print- to customers, which includes laser direct imaging. ed circuit processing.

Bernie Kessler: Pioneering Key PCB Makers Strategize 6 Spirit Then and Now 9 to Meet Industry Demands

I-Connect007’s Patty Goldman sat down with long The computer/peripheral application is expected time friend and IPC Hall of Famer Bernie Kessler at to witness the highest growth followed by the IPC APEX EXPO 2015 in San Diego. Among other communication applications. Nippon Mektron, things, the two discussed the early days of IPC and Zhen Ding Technology Holding Limited, Young the origins of APEX EXPO. Poong Electronics Co. Ltd., Unimicron Technol- ogy Corp., and Samsung Electro-Mechanics are among the major suppliers of PCBs. 7 Manz: A Total Process Solution N.A. PCB Book-to-Bill J ratio Strengthens At the recent CPCA Show in China, I-Connect007 Publisher Barry Matties had a chance to speak with “Although North American PCB sales continued Alex Liu, the deputy general manager of the PCB slightly below last year’s levels in February, book- business unit for Manz. Manz has focused on cre- ings strengthened,” said Sharon Starr, IPC’s direc- ating a process from direct imaging to wet pro- tor of market research. “This increased the book- cessing. With more entrants into the direct imag- to-bill ratio…it has been in positive territory for the ing arena, Liu feels that this approach gives Manz past five months, which is a positive indicator for and their customers an advantage. sales growth in the first half of 2015.”

For the latest PCB news and information, visit: PCB007.com

MayMay 20152015 • The PCB Magazine 71 calendar EVENTS International Conference on For the IPC Calendar of Events, click here. Soldering & Reliability 2015 May 19–21, 2015 Markham, Ontario, Canada For the SMTA Calendar of Events, click here. Toronto SMTA Expo & Tech Forum For the iNEMI Calendar of Events, click here. May 21, 2015 Markham, Ontario, Canada For the complete PCB007 Calendar of Events, click here. Huntsville Expo & Tech Forum June 4, 2015 Huntsville, Alabama, USA Puget Sound Expo & Tech Forum May 7, 2015 ITI & IPC Conference on Emerging Bellevue, Washington, USA & Critical Environmental Product Requirements Wisconsin Expo & Tech Forum June 9, 2015 May 12, 2015 Fort Lee, New Jersey, USA Milwaukee, Wisconsin, USA ITI & IPC Conference on Emerging IPC Technical Education & Critical Environmental Product May 13–14, 2015 Requirements Fort Worth, Texas, USA June 12, 2015 Milpitas, California, USA

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Advertiser Index Coming Soon to atg Luther & Maelzer GmbH...... 21 Atotech...... 53 The PCB Magazine: Burkle North America...... 59 Camtek...... 47 DIS...... 25 Electra Polymers...... 55 June: ESI...... 17 FASTechnologies...... 35 Flexibles, Gardien...... 29 Insulectro...... 41 Stretchables and IPC...... 49 Isola...... 7 Wearables Matrix USA...... 15 Mentor...... 37 Meptec...... 3 Mortech...... 33 July: Mutracx...... 23 Nano System, Inc...... 5 Supply Chain OMG Electronic Chemicals...... 43 Panasonic...... 57 Management Plasma Etch...... 9 Prototron...... 63 Rogers...... 61 Steve Williams Consulting...... 31 August: Taiyo America...... 45 Technica...... 65 The War on The PCB List...... 2, 69 Ucamco...... 39 Process Failure Ventec...... 19 Viking...... 51

May 2015 • The PCB Magazine 73