D.G. Nova update -- crapacitors strike again

[Tom Jennings]

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...