3
\$\begingroup\$

I am specifying a solid polymer capacitor (Panasonic 80SXV47M) in a power supply application required for a long service life. Does this component degrade when stored powered off for long periods of time? How does this affect the service life?

\$\endgroup\$

1 Answer 1

3
\$\begingroup\$

Short answer: Yes, it degrades and it will impact service life negatively.

Longer answer:

First of all: It all depends on the timeframes we're talking about. 10 years, 100 years?

But less than a Electrolytic capacitor with a liquid electrolyte since it's a solid polymer and not a liquid that in some cases contains solvents.

Also, according to Würth Electric Online, Aluminium Polymer capacitors react more favorably to a reduction in temperature by increasing lifetime by a factor of 5 for every 10K lower temperature while the factor is only 2 in standard electrolytic caps (you could also argue that they react less favourable to increases in temperature but since lifetime is thankfully given at maximum temperature, this claim seems ok to me).

So while hard numbers are hard to come by the consensus seems to be that solid electrolytes are less prone to effects of aging in storage as well as in use.

But keep in mind, that there is a ton of experience from the last 60-80 years of using electrolytic capacitors while this kind of experience is lacking for solid polymers.

\$\endgroup\$
8
  • 2
    \$\begingroup\$ Incidentally, they fail for similar but opposite reasons, of a sort: the conductive polymer degrades with exposure to moisture, while the electrolytic literally dries up. Both are mediated by the quality of the rubber seal, the diffusion of molecules through it. \$\endgroup\$ Commented Jul 10 at 13:44
  • \$\begingroup\$ @TimWilliams wow. That's an interesting fact. Didn't think about that but absolutely true. But getting moisture into the electrolyte will make the classic liquid electrolyte capacitors to (as we learned the hard way in the early 2000s)... \$\endgroup\$
    – kruemi
    Commented Jul 10 at 14:12
  • 1
    \$\begingroup\$ Mmm, AFAIK the 2000s "cap plague" was bad formulation causing corrosion of the electrodes, and I think that caused the contents to expand and split the top? And then electrolyte loss, and doubly rising ESR, were inevitable. But it might've been other mechanisms; I haven't read a study on that event. \$\endgroup\$ Commented Jul 10 at 15:13
  • 1
    \$\begingroup\$ Then I did remember correctly; thanks for confirming! \$\endgroup\$ Commented Jul 11 at 3:12
  • 1
    \$\begingroup\$ @kruemi I discovered this today, the document which was posted from würth was very useful. It looks like 10 years is a reasonable aspiration, with a some maintenance periods to reform the caps and test leakage current performance \$\endgroup\$
    – droseman
    Commented Jul 11 at 17:08

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.