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Understanding Polymer and Hybrid Advanced capacitors based on conductive polymers maximize performance and reliability

The various polymer and hybrid capacitors have distinct sweet spots in terms of their ideal voltages, frequency characteristics, environmental conditions and other application requirements. In this paper, we’ll show you how to identify the best uses for each type of advanced . We’ll also highlight specific applications in which a polymer or hybrid capacitor will outperform traditional electrolytic or even capacitors.

POLYMER CAPACITOR VARIETIES

Polymer capacitors come in four main varieties, including the hybrid. Each type has different electrolytic and Hybrid capacitor technology combines the performance benefits of materials, packaging and application targets: electrolytic and polymer capacitors. • Layered polymer aluminum capacitors use conductive Capacitors may seem simple enough, but specifying them has polymer as the and have an aluminum actually grown more complex in recent years. The reason why (see Figure 1). Depending on the specific model, these comes down to freedom of choice. The universe of capacitors capacitors cover a voltage range from 2-25V and offer has expanded greatly over the past few years, in large part between 2.2-560µF. The distinguishing because of capacitor designs that take advantage of advances electrical characteristic of these polymer capacitors is in conductive polymers. their extremely low equivalent series resistance (ESR). For example, some of our SP-Cap™ polymer capacitors have These advanced capacitors sometimes use conductive polymers ESR values as low as 3mΩ, which is among the lowest in to form the entire electrolyte. Or the conductive polymers can be used in conjunction with a liquid electrolyte in a design known as a hybrid capacitor. Either way, these polymer-based capacitors Molding Paste offer a performance edge over conventional electrolytic and Resin ceramic capacitors when it comes to: Terminal

• Electrical characteristics.

• Stability.

Al2O3 • Longevity. Silver Paste Carbon Aluminum Foil • Reliability. Terminal Polymer • Safety. Figure 1 • Life cycle cost.

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the industry. Packaged in a molded resin as compact surface mount devices, these layered polymer capacitors have a low profile. As a result of the electrical and form Back Plate factor characteristics, they have applications in a variety of handheld electronic devices or other applications that require a low-profile capacitor that will not interfere with a nearby heat sink. Rubber Seal Terminal

• Wound polymer aluminum capacitors are also based on conductive polymers and aluminum, but they have a wound Aluminum foil structure (see Figure 2). The wound polymer capacitors Foil

cover a wider range of voltages and values Aluminum Spacer than other types of polymer capacitors. Voltages extend Foil Al O from 2.5 to 100V, while capacitances run from 3.3 to 2700µF. 2 3 Electrolyte Impregnated in Spacer Like the layered polymer capacitors, the wound style Polymer has extremely low ESR values. Some of our OS-CON™ Figure 2 capacitors, for instance, have ESR values below 5mΩ. The wound style can Molding also be surface mounted, though they are not Resin Terminal quite as compact as the layered capacitors.

Terminal Silver paste Ta2O5 Sintered Carbon • Polymer tantalum capacitors employ a polymer as the electrolyte and have a tantalum cathode (see Figure 3). They span voltages from 1.8 to 35V and Figure 3 capacitances from 2.7 to 680µF. They, too, have low ESR values. They, too, have low ESR, with some of our POSCAP™ capacitors exhibiting ESR values as low as 5mΩ. Packaged in a molded resin case, the tantalum polymer capacitors are among the most compact on the market. Our POSCAP M size, for example, measures just 2.0 by 1.25 mm. Though compact, a wide range of sizes is available for this capacitor type.

Panasonic Two Riverfront Plaza, 7th Floor, Newark, NJ 07102-5490 www.panasonic.com/industrial Aluminum Case • Polymer hybrid aluminum capacitors. As their name suggests, these capacitors use a combination of a liquid and conductive polymer to serve as the electrolyte (see Figure Back Plate 4) and aluminum as the cathode. Think of this technical approach as the best of both worlds: The polymer offers high conductivity—and a correspondingly low ESR. The liquid portion of the electrolyte, meanwhile, can withstand high Rubber Seal Terminal voltages and provide higher capacitance ratings due to its large effective surface area. The hybrid capacitors offer a voltage range from 25 to 80V and capacitances between 10 Aluminum and 330µF. At 20 to 120mΩ, ESR values for hybrids are higher Foil

than other types of polymer capacitors, but still very low Aluminum Spacer considering the higher power applications they address (see Foil

sidebar). Al2O3 Hybrid Electrolyte Impregnated in Spacer ADVANTAGES Polymer + Electrolyte Liquid Despite differences in their materials and construction, the four Figure 4 types of polymer capacitors share a collection of desirable electrical properties:

• Great frequency characteristics. Thanks to their ultra low ESR values, polymer capacitors have a low impedance near their point (see Figure 5). And lower impedance Figure 5 reduces AC ripple in power circuits. Our testing has ESR lowers impedance near the resonance point, reducing AC ripple.

IMPEDANCE CHARACTERISTICS

Impedance Capacitance: ½πfC : 2πfL, where L = ESL Resistance: ESR

Impedance (Z) Impedance (Z)

Frequency Frequency

Z Large: Z Small: Ripple Ripple Z Large: Z Small:

Panasonic Two Riverfront Plaza, 7th Floor, Newark, NJ 07102-5490 www.panasonic.com/industrial DC Bias 10 STABLE CAPACITANCEDC Bias Reliable Capacitors For IT 100 DC Bias 10 -10 Infrastructure 0 -2-10 -10

Information technology infrastructures have a little-known ) -3-20 (% -20 C weak link: The capacitors in their power supplies. ) -4-30 / (% ) dC

C -30 -5-40 / Conventional electrolytic capacitors tend to fail prematurely (% C dC -40 when their liquid electrolyte dries up‚ which happens in / -6-50 dC -50 response to elevated temperatures and long on times. -7-60 -60 -8-70 Conventional tantalum capacitors are one possible solution -8-70 to these premature failures. However, tantalums require -90 01234567 -9-80 voltage derating to avoid a very undesirable failure mode— DC Bias (V) 01234567 -90 DC Bias (V) namely, the potential for fires. 01234567 DC Bias (V) More advanced polymer-based capacitors have emerged Temperature Range 2200 as a way to improve lifecycle and reliability of IT equipment Temperature Range 2200 such as servers, switches, routers and modems. Temperature Range ) 2200 (%

C 1100 )

Polymer wound capacitors such as OS-CON do not have a C/ (%

C 1100 ) C/

liquid electrolyte and therefore can have extremely long life. (%

C 1100

C/ 0 POSCAP polymer-tantalum capacitors contain no oxygen --555-5 -3535 -1-1555 5 2525 4545 6565 8585 10105 0 in their formulation. So they are not prone to combustion --555-5 -3535 -1-1555 5 2525 4545 6565 8585 10105 0 Temp. ( ) upon failure. SP-Caps also have a similar benign failure --555-5 -3535 -1-1555 5 --110 2525 4545 6565 8585 10105 mode. --110 Temp. ( ) --110 Temp. ( ) All three families of advanced capacitor also offer the --220 features required for information infrastructure: --220 --220 -3300 • Compact size. -3300 • Low ESR MLCC -3300 • High Ripple Current MLCCMultilayer (6.3V47µF/3216/X5R) • Long Life. PolymerMLCCMultilayer ceramic capacitor capacitor (6.3V47µF/3216/X5R) PolymerPOSCAP,Multilayer ceramicSP-Cap capacitor capacitoror OS-CON (6.3V47µF/3216/X5R) (6.3V47µF) PolymerPOSCAP, SP-Cap capacitor Figureor OS-CON 6 (6.3V47µF) POSCAP, SP-Cap or OS-CON (6.3V47µF)

revealed as much as a fivefold reduction in peak-to-peak deliver subpar performance in the field. Hybrid capacitors voltage changes when comparing polymer capacitors to add another dimension to capacitance stability. They keep conventional low-ESR tantalum capacitors. a stable capacitance in the face of common operating conditions—high frequencies and low temperatures—that • Stable capacitance. With ceramic capacitors, capacitance reduce the capacitance of conventional liquid electrolytic drifts in response to temperature changes and DC bias. capacitors. Polymer capacitors have no such problem and remain (see Figure 7). stable over time (see Figure 6). This stability is particularly important in industrial and automotive applications, which • Enhanced safety. Conventional electrolytic capacitors tend to experience fluctuations in operating temperatures. can suffer from safety issues that could cause them to We’ve seen cases where elevated temperatures caused short circuit and fail. The problem arises when electrical an effective capacitance loss of 90% or more for ceramic or mechanical stresses create defects or discontinuities in capacitors, meaning that the conventional capacitors the oxide film that forms the capacitor’s . Polymer

Panasonic Two Riverfront Plaza, 7th Floor, Newark, NJ 07102-5490 www.panasonic.com/industrial HYBRID CAPACITOR capacitors have a self-healing capability that eliminates Capacitance vs. Frequency this failure mode. The repair takes place in response to the CapacitancePERFORMANCE vs. Frequency 1000.0000 joule heating that occurs when a dielectric defect triggers a 1000.0000 Capacitance vs. Frequency short circuit. The heating breaks the molecular chain of the 1000.0000

conductive polymer near the defect, driving up its resistance 100.0000 and effectively forming a barrier against any current leaking 100.0000 from the electrode (see Figure 8). In the case of hybrid 100.0000 F)

capacitors, an additional self-healing mechanism comes F) 10.0000 C ( Good 10.0000 C ( Good into play—because the liquid electrolyte causes current F) 10.0000 C ( flow near the defect to reoxidize the aluminum. We have Good 1.0000 conducted numerous over-voltage tests to demonstrate 1.0000 the self-repairing nature of polymer and hybrid capacitors. 1.0000 One such test compared our SP-Cap polymer capacitors 0.1000 0.1000 100 1,000 10,000 100,000 1 M 10 M to a conventional tantalum-MnO2 capacitors. The polymer 100 1,000 10,000 100,000 1 M 10 M 0.1000 Frequency (Hz) model withstood short currents as high as 7 amps, while the 100 1,000 10,000Frequency100,000 (Hz) 1 M 10 M started smoking at 3 amps and ignited Frequency (Hz) at 5 amps. This safety enhancement has important design Hybrid capacitors offer stable capacitance at high frequencies. and cost implications. Conventional tantalum capacitors are normally derated in use by 30 to 50% their labeled voltage ESR vs. Temperature 100 ESR vs. Temperature to ensure that they operate safely. This derating, while a 100 ESR vs. Temperature common and accepted engineering practice, results in an 100

upsizing of capacitors and increased cost. For our polymer 10 10 capacitors, by contrast, we guarantee operation at 90% of ) 10 ) ( the full-rated voltage.

( 1

) 1 (

Good 1 Good 0.1 0 Polymer And Hybrid Good .1 0.1 Capacitors Are Road Ready 0.01 0.01-60-20 20 60 100 140 Polymer capacitors are seeing increasing use in automotive -60-20 20 60 100 140 0.01 Temperature ( ) electronic applications. Our polymer and hybrid capacitors -60-20 TemperaturESR20 (100kHz)e60 ( ) 100 140 meet the following automotive production requirements: TemperaturESR (100kHz)e ( ) OS-CON, Hybrid and POSCAP models comply with ESR (100kHz) •  E-Cap AEC standards. E-Cap Hybrid • Capacitors are produced in a TS16949 certified E-CapHybrid production facility. Hybrid capacitors offer stableHybrid ESR even at temperatures as low as -55ºC. • Production Part Approval Process (PPAP). Figure 7

Panasonic Two Riverfront Plaza, 7th Floor, Newark, NJ 07102-5490 www.panasonic.com/industrial Pre-Short Short Heating Defect Isolation

Electrode Element Micro Defect Short Circuit Current Isolated Conductive Polymer Dielectric Oxidation Film Conductive Polymer Layer Figure 8

Polymer capacitors have been in production since 1990. But they Robust Capacitors For continue to evolve, both in terms of their electrical characteristics and their sizing. Consider our aluminum polymer capacitor line, Industrial Use for example. Upcoming models will drive ESR even lower and capacitance even higher—to 2mΩ and 680µF, respectively. The increased use of in industrial applications Or looking at the tantalum polymer line, new models will offer has created a need for more robust capacitor solutions. reductions in ESR in smaller surface mount packages. For These demanding applications often have unforgiving example, the 3.5x2.8-mm B-Size capacitors will likely see a drop operating environments that are not friendly to in ESR from 9 to 6mΩ. conventional capacitor technology such as aluminum electrolytics. Our hybrid capacitor line is evolving too. We are expanding the Capacitors utilizing polymer technology, such as our voltage coverage with new 16 and 100V capacitors. Life cycle OS-CON and Hybrid models, are ideally suited for these and ripple current specifications are also slated for improvement applications because they offer a combination of: in upcoming product releases. • Long Life These continuous technical improvements will make polymer • Low ESR and hybrid capacitors an increasingly attractive alternative to • High Ripple Current conventional tantalum-MnO2 and multi-layer ceramic capacitor • High Temperature (MLCC) technologies. • High Voltage • High Capacitance Industrial applications that can benefit from advanced polymer and hybrid capacitors include motor drives, power inverters and specialty lighting.

Controller applications can take advantage of polymer- based capacitors too. Our POSCAP polymer tantalum and SP-Cap models have all the electrical characteristics we just mentioned but also have compact form factors that make it easy to integrate them in industrial control systems.

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Driven by miniaturization of electrical components and higher Hybrids maximize reliability. Capacitors cannot just switching frequencies of many electrical devices, hybrid be small, they also need to hold up under challenging capacitors have started to get more traction. electrical and environmental conditions. By nearly every measure, hybrid capacitors outperform equivalent aluminum Hybrids are known for their stable electrical characteristics electrolytic and polymer capacitors hands down. To take at high frequencies. These robust capacitors also have other a few examples, hybrid capacitors have significantly compelling advantages that make a difference in applications better endurance and humidity resistance than either their such as computer servers, backup devices and networking electrolytic or polymer counterparts. Hybrids also have gear as well as industrial motors, automotive engine control significantly higher tolerance for large ripple currents, inrush units, security cameras and LED lighting. Among the currents and elevated temperature (See Figure 9). advantages: Taken together, the size and reliability produce a strong cost Given the ongoing push to miniaturize Hybrids are compact. benefit for using hybrid capacitors—in spite of their higher electrical equipment, the size of capacitors has taken on upfront prices. The higher ripple current specification alone a growing importance. Surface mount hybrid capacitors can result in a 20% reduction in cost by increasing the life measuring just 6.3 x 5.8 mm can handle 35V and offer a cycle of the capacitor. In the 48V application capacitance of 47µF. The small size can save a significant we just mentioned, the hybrid capacitors had a total cost amount of board space. In a recent 48V power supply 50% lower than the equivalent aluminum electrolytic application, hybrid capacitors occupied just 13% of the capacitors, with the savings coming from reductions in board space required by aluminum electrolytic capacitors. board cost, warranty cost and ability to withstand high ripple current. Capacitance Change ESR (Ω)

40 0.140 Upper Limit Upper Limit 30 0.120

20 0.100 10 0.080 0 0.060 ESR ( Ω ) ∆ cap. (%) 0mA -10 0.040 -20 0.020 -30 Lower Limit -40 0.000 0 1,000 2,000 3,000 4,000 5,000 6,000 0 1,000 2,000 3,000 4,000 5,000 6,000 Time (h) Time (h)

40 0.140 Upper Limit Upper Limit 30 0.120 20 0.100 10 0.080 ripple ) 0 0.060 ESR ( Ω ) ∆ cap. (%) -10 Figure 9 0.040 1300mA -20 (standa rd Hybrid capacitors exhibit high -30 0.020 Lower Limit reliability when subjected to high -40 0.000 0 1,000 2,000 3,000 4,000 5,000 6,000 0 1,000 2,000 3,000 4,000 5,000 6,000 ripple currents. In recent testing, Time (h) Time (h)

the capacitors had the electrical 40 0.140 Upper Limit Upper Limit characteristics at no load and 30 0.120

rated ripple current (1300 mA) 20 0.100 conditions. At three times 10 0.080 the rated ripple current (3600 0 0.060 ESR ( Ω ) mA), the capacitor’s electrical ∆ cap. (%) -10 (overripple )

3600mA 0.040 characteristics did change, but -20 0.020 -30 no shortage took place. Lower Limit -40 0.000 0 1,000 2,000 3,000 4,000 5,000 6,000 0 1,000 2,000 3,000 4,000 5,000 6,000 Time (h) Time (h)

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