Panasonic engineers Jing Liu and Christian Gellmann answer questions from TechTime and labratsgonewild.com around polymer capacitors
TechTime: What are the prospects to minimize the polymer capacitors package, and embed them into future SoCs?
Panasonic: Now, we have a wide range of conductive polymer capacitors, D size(7343), B size(3528), A size(3216) and S size(2012). At this moment, we have no plan to embed them into SoCs, but we believe A size or S size POSCAP will help to reduce the surface mount space around SoCs as total solutions.
TechTime: What's the biggest problem / limiting factor you encounter when designing low-ESR caps?
Panasonic: Generally speaking, it is difficult to realize smaller and thinner capacitors with lower ESR. But, Panasonic will overcome it as the No.1 polymer capacitor manufacturer.
TechTime: What aspect of production / design primarily determines manufacturing cost, especially cost differences between different components? Is it just a marketing thing (better specs at a premium) or is there a tangible cost offset?
Panasonic: It depends on materials, manufacturing process and amount of production.
TechTime: Has there been a problem with counterfeit Panasonic capacitors? If so, how easy are they to identify, and what should I look for?
Panasonic: Unfortunately, yes. We find counterfeit Panasonic capacitors, usually sourced through unofficial channels and brokers (grey market). We can easily judge whether it is genuine or not. But to avoid quality issues, please purchase our products through official sales route from beginning.
TechTime: Is there such a thing as a developers cap-sampler pack, and if so, to whom should we be speaking to and where do we go to get one from?
Panasonic: Basically, we offer sample kit only for some limited customers. So, please purchase our capacitors one by one on the web or etc. For more details, please contact us.
TechTime:I know this is supposed to be about polymer capacitors, but what's the deal with reverse biasing electrolytic capacitors? How can one find what is the maximum voltage/frequency for a given electrolytic capacitor when reverse biased?
Panasonic: Please contact us when there is a concern that circuit operation may cause reverse voltage.
TechTime: What do you see as the way forward for high-temperature (150C, 175C) DC-link capacitors? PP-Film? Electrolytic? Glass?
Panasonic: We are developing 150°C conductive Polymer Hybrid capacitors (Max category temperature 105 degrees Celsius) to launch in several years. Also, we are developing 150°C film capacitor in the long run. We are developing them for automotive customers (especially DC-link, ECU etc.).
TechTime: Do you have any software tools for comparison like Murata?
Panasonic: We don’t have such a software tool for comparison like Murata. But, Simulation Data Libraries and Parametric Search are available as follows.
Simulation Data Libraries
Polymer Hybrid and lytic aluminum capacitors
TechTime: It's pretty amazing. I never realized that the capacitance of X7R caps is degraded with increasing voltage. The larger size caps have less degradation.
Panasonic: One major feature against MLCC is capacitance stability against bias voltage and temperature. Polymer does not require design margins such as voltage derating or capacitance decrease, making them very handy for applications used in changing load and environmental circumstances.
Labratsgonewild.com: Polymer capacitors are usually compared to electrolytic capacitors (in terms of lifespan, price, voltage and ESR ratings). How about their thermal coefficient of capacitance? How stable is it across -40C to 125C? What temperature range is it most stable?
Panasonic: Conductive polymer capacitors have very stable technical characteristics (Cap, ESR) over full temperature range and against aging (long endurance). This make them most suitable for application in low temperature (eg. outdoor) and high temperature (eg. fanless cabin) application, where electrolytic type facing dry up problem.
Labratsgonewild.com: We usually see these capacitors in metal cans - and large SMD - is there a direction to go to 0805, 0603 sizes?
Panasonic: We already have line-ups of S size(0805) of POSCAP.
Labratsgonewild.com: We usually see these capacitors on decoupling applications - are there polymer capacitors capable of performing well in filtering applications?
Panasonic: Panasonic conductive polymer capacitors are also suitable for filtering applications due to their low ESR and large allowable ripple current.
Labratsgonewild.com: How is its voltage coefficient of capacitance compared to electrolytic and tantalum?
Panasonic: If the size and materials are same, the voltage coefficient of capacitance is almost same.
E.g. general tantalum vs polymer tantalum.
Labratsgonewild.com: Are there polymer capacitors that can par with X7Rs and NP0s in terms of filtering applications?
Panasonic: It depends on the frequency of power supply. We can propose a solution if circuit conditions are provided.
Labratsgonewild.com: Are there polymer capacitors that can be used for compensation? Say, ranging from a few pFs?
Panasonic: No, we don’t have these
Labratsgonewild.com: Polymer capacitors are viewed to be more expensive (that why we usually see them in high end power supplies etc.). Is there a direction of having cheaper polymer caps for low ender applications?
Panasonic: If you compare conductive polymer capacitors with other capacitors one by one, they might be expensive. But, conductive polymer capacitors can replace several other capacitors by one. We think less component counts will lead to less cost circuits as a total.
Labratsgonewild.com: How do Panasonic qualify the number of years polymer capacitors can last?
POSCAP:2,000 hours at 105°C/ 1,000 hours at 125°C
SP-Cap:2,000 hours at 105°C
OS-CON:Up to 5,000 hours at 105°C/ 2,000 hours at 125°C
Polymer Hybrid:10,000 hours at 105°C/ 2,000 hours at 125°C
*20°C operating temperature reduction, 10 times longer life expectance
**Arrhenius formula 10°C operating temperature reduction, double of life expectance
Labratsgonewild.com: How does Panasonic ensure reliability of the polymer capacitors?
Panasonic: We have unique technologies and know-hows acquired in the long experience to ensure reliability.
Labratsgonewild.com: What ESD tests are done one the polymer caps before they get qualified for consumers to use?
Panasonic: ESD doesn’t matter to our polymer capacitors.
Labratsgonewild.com: Does Panasonic offer special packaged polymer caps for aerospace applications?
Panasonic: We do offer entertainment solutions for aerospace applications.
Labratsgonewild.com: Most integrated circuits are rated up to 125°C. However, most of the polymer capacitors are only rated up to 105°C - do you see this as a disadvantage over the ceramic type capacitors?
Panasonic: Most electronic products work under 105°C so we have limited line-ups of 125°C capacitors. But, we are developing more 125°C line-ups to meet customers’ expectations.
Labratsgonewild.com: There were reports of tantalum caps bursting when electrically over-stressed. Is this also true for polymer caps?
Panasonic: It’s true for general tantalum, but not true for conductive polymer tantalum capacitors because polymer capacitors have self-healing functions.
Labratsgonewild.com: When using polymer caps how much voltage headroom should we use? 20%?
Panasonic: Basically, concerning applied voltage, 90% and below of the rated voltage of the POSCAP is recommended and less than the rated voltage of SP-Cap, OS-CON and Polymer Hybrid is recommended.
SP-Cap, OS-CON and Polymer Hybrid 100%
Labratsgonewild.com:Can you compare the solder reflow tolerance on polymer caps compared to the other caps?
Panasonic: Please inquire individually on
Labratsgonewild.com: Does the capacitance shift when polymer capacitors are exposed to prolonged soldering? Do they heal in time?
Panasonic: We don’t think the capacitance shift so much because soldering time is not so long to have some impact. Please provide soldering conditions for individual checking.