So ive been very quite recently - talk about busy (lazy hehe) schedule. So a few months back I was told that capacitor experts from panasonic Jing Liu and Christian Gellmann are willing to answer question about thier line of polymer capacitors - labrasgonewild folks won't let this once in a blogging lifetime opportunity to pass with out submitting our own questions. I didn't expect our questions would be picked - come on there are a lot of cap-geeks out there haha.
Now capacitors are my favorite components - when I graduated college I though I knew most about them like big caps are placed near the source while smaller ones are placed near the chip, ect... But in my first few months in my job as a test engineer I realized I knew almost nothing at all about them, ive learned about X7Rs, NP0s and things like the voltage coefficient of capacitance (I was like wutda!? when I first heard about that term haha). Now Poly-caps aren't new to the market, I usually don't use them for my projects because they aren't available in the local electronics store. Ide like to try them out though - specially for supply decoupling ive heard a lot of good comments about the stability of these things. Here is the questions that we pitched in along with the answers from the experts:
Now capacitors are my favorite components - when I graduated college I though I knew most about them like big caps are placed near the source while smaller ones are placed near the chip, ect... But in my first few months in my job as a test engineer I realized I knew almost nothing at all about them, ive learned about X7Rs, NP0s and things like the voltage coefficient of capacitance (I was like wutda!? when I first heard about that term haha). Now Poly-caps aren't new to the market, I usually don't use them for my projects because they aren't available in the local electronics store. Ide like to try them out though - specially for supply decoupling ive heard a lot of good comments about the stability of these things. Here is the questions that we pitched in along with the answers from the experts:
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?
Panasonic: lifetime:
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.
POSCAP 90%
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?
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.
If you wanna check out the rest of the questions please visit this page and click on the Q&A tab :)
Cheers,
bootfetch
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