Paul,

Thank you for the reply. I am a little confused when you wrote about
dissimual metals corrosion. I believe the concern here is atmospheric
degradation due to contaminates
( gases, liquid acids, and ionic submicron particles ) plus oxidation
will build a non-
conductive layer on the surface. I don't believe electrolosis is even a
minor factor in this process. ( But what do I know!)

It is fairly common for flght crews on commerial airlines to "reset"
circuit breakers when systems "freeze". Most of the hardware is forced
air cooled internally using dry (<5% RH) unfiltered ( very dusty) air.

There have also been cases where multiple systems have "lockup" creating
some very
interesting times for the pilots. ( The cause for many of these
multi-systems failures
have never been found using standard and special tests)

I have personally been involved in several of these investigations and
it was very frustrating. This failure mode is the first one I have found
which provides a reasonable
explanation of what happened. The problem is what does one do about it.

You are quite right about no one wanting to talk about CMOS Latchup.
Sort of an industry secret I guess. I tried asking several vendors about
Latchup voltage levels
for their products and was politely ignored. ( Go away and don't bother
me)
Oh well!

D. A. Douthit

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