日本語
I have problems with a switched mode power supply,
where a film capacitor seems to misbehave in the feedback loop.
I use film caps due to microphonic issues with ceramics in previous generations.
It is a 10 nF, 63V cap, size 1812.
The capacitor seems to leak slightlty, varying slowly,
causing a few hertz of very low (single digit mV) ”ripple” on the output voltage.
I also see, in a few cases, a small sensitivity to signals from a trace between the pads,
where the signal transitions seem to couple capacitively to the capacitor.
What might happen to a film capacitor if its max specified reflow temperature
is exceeded during the soldering process?
- Comments(1)
A****min
Nov 21.2019, 11:20:16
SMT stacked PPS film caps can have leakage problems, indeed. It's a flux and cleaning problem, AFAIK. Don't know that it causes any significant excess noise at frequencies relevant to control loops though.
Seems more likely there's an outside influence you haven't accounted for..? How have you proven that the problem is due to varying capacitor leakage?
