I am troubleshooting a design that uses a 47 µF 20 V tantalum SMD cap across a 15 Vdc rail.
While the derating guidelines I follow dictate a 50% voltage derating for tantalum caps, the design I'm looking at slipped through the cracks, and 15 Vdc is applied continuously.
Is it possible that these tantalum caps could short from over-voltage and then self-heal, causing the overall circuit to malfunction for a moment, but upon later inspection appear fine?
These caps are across the rails of a relay driver IC. Supposedly relay contact closures were detected, but no commands from the micro that would result in relays energizing were recorded.
If self-healing tantalum caps are a possible culprit, what is the timescale for the self-healing process? I have not been able to find any data with regard to healing time.