EEVblog 1486 – What you DIDN’T KNOW About Film Capacitor FAILURES!

You might think you know how film capacitors fail and degrade in capacitance over time – self-healing due to surges, right? WRONG! Capacitor expert and AVX Fellow Ron Demcko confirms what’s really going on after a teardown of some failed and one good polypropylene X class capacitor.

00:00 – Teardown of a some failed film capacitors
00:52 – Self Healing and drop in capacitance
01:44 – Capacitance Measurements
02:15 – Teardown of a new Suntan brand polypropylene X2 film capacitor
03:03 – Different failure modes based on size and winding pressure
05:52 – Unwrapping the film
07:51 – The film inside a NEW film capacitor
09:19 – Teardown of the FAILED uTx brand heater capacitor with half capacitance
10:06 – How Schoopage and the end pin terminations work
12:23 – Teardown continues…
12:45 – WOW! What on earth is this?
14:54 – Elecami Wolf also did a teardown
16:05 – Teardown continues…
17:01 – Separating the film showing both slef-healing and extensive metal film corrosion
18:29 – Another uTx brand failed film capacitor from a Corsair PSU, with 90% loss in capacitance!

19:55 – Let’s call an expert! Ron Demcko from AVX tells us the REAL REASON for the failure! It’s moisture ingress and corona demetallization!

Metallized Film Capacitor Lifetime Evaluation and Failure Mode Analysis report:
Film Capacitors construction:
Film Capacitors self-healing explanation:
Film Capacitor types:


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