1 Apr
2005
1 Apr
'05
4:57 p.m.
On Fri, 1 Apr 2005, Christian R. Fandt wrote:
Oh yeah, these are likely monolithic ceramic caps. We
used them in various
products as logic supply bypass caps where I used to work. I personally have
not seen any failures like this in my own experience. I have a bunch of 0.1
uF parts on reels around here somewhere.
Well this one sure failed -- turned brown from heat! It was just an
ordinary monolithic, but I replaced them all just the same :-)
However, disc ceramic capacitor failures were a recent
topic of discussion on
one of the old radio email lists. Failure mode was migration of the capacitor
plate material through the disc because of flaws or cracks. High leakage
current or outright shorts were the problems observed. I can see that
happening with axial monolithic caps if there were manufacturing quality
problems with the ceramic materials used to make the parts.
As tolerances tighten in general parts are run closer to their
ratings; my solution is to use 100V and up disk ceramics. I stock
only so many parts, this makes life easier...
My guess is that all the tants that fail, lower-voltage ratings
fail more often than higher-voltage... just guessing...