Hi Reuven, Bev, Pratap, and IPC LF Listservers,

I need to quickly agree with Bev. Back just awhile ago I gave a reference to
an open letter published by the IEEE in it's CP&MT magazine about Lead Free
and it included something about whiskers. Mike P from Univ of MD (CALCE) was the
lead author of that article with other contributors. While I believe Pratap
has to be right about bolts and such, creating greater tin whisker problems the
cases I have seen from the military/space people are more than bolts (or
designed in stress concentrations).

From what I remember this test from NEMI and a few others are supposed to
high stress BEYOND normal acceleration the ability to create whiskers. Which
means that in real life one should not expect whiskers as long as the failure
mechanism (s) were the same as the NEMI tests were striving to stress beyond
normal. From what I know about reliability this isn't truely an accelerated test
where equations can be used from the results to mathematically bring one back to
real life. It is more an over the top stress test.

Yours in Engineering, Dave
YiEngr, MA/NY DDave


> Reuven,
> I would like to point out that there is no "guarantee".  The NEMI tests and
> all others proposed are somewhat more likely to grow whiskers, but the
> phenomenon is not completely understood, although we as an industry are probably
> closer than we were five years ago.
> regards,
> Bev Christian


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