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Because aluminum electrolytic capacitors generally incorporate a venting mechanism for over-temperature/over-pressure events, are they suitable for complete encapsulation in potting compound?

Specifically, I am evaluating the compatibility between a surface mount 10V Nichicon UWT-series cap and a polyurethane-based potting compound used in automotive applications.

Is it OK to pot this type of capacitor? If encapsulation is not recommended, what alternate types should I consider for 100µF bulk capacitor purposes?

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  • \$\begingroup\$ Re alternatives: you didn't mention voltage rating. \$\endgroup\$
    – Andy aka
    Commented Jul 28, 2020 at 17:24
  • \$\begingroup\$ @Andyaka Sorry, it's a 10V-rated cap. The device supply voltage is max 3.6V. \$\endgroup\$
    – JYelton
    Commented Jul 28, 2020 at 17:32
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    \$\begingroup\$ Well there are doubts about potting e-caps but you can parallel up ceramic capacitors and pot them no problem. \$\endgroup\$
    – Andy aka
    Commented Jul 28, 2020 at 17:36
  • \$\begingroup\$ @Andyaka I'm considering aluminum polymer (Nichicon PCG series), but I'm unsure if they have similar venting/safety issues. I sought to ask more experienced engineers while I continue to research. :) \$\endgroup\$
    – JYelton
    Commented Jul 28, 2020 at 17:41
  • \$\begingroup\$ I like Andy's idea here. Two 47µF X7R/Y5V ceramics in parallel will outperform many 100µF electrolytics and never leak. \$\endgroup\$
    – rdtsc
    Commented Jul 28, 2020 at 18:25

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Here are some cautions from TDK:

enter image description here

Seems like partially potting a capacitor with a top vent (letting the top part poke out) may be acceptable.

Be careful about the temperatures, PU potting compounds are exothermic when curing and can get very hot.

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    \$\begingroup\$ I've seen it done before, where everything is potted, but the top 0.5 - 1mm of elec. caps are exposed. \$\endgroup\$
    – Aaron
    Commented Jul 28, 2020 at 21:19
  • \$\begingroup\$ @Aaron Just to clarify, leaving some of the cap exposed isn't an option in my application because of moisture and potential corrosion of the cap surface. \$\endgroup\$
    – JYelton
    Commented Jul 28, 2020 at 22:05

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