[ARC5] Re: [Milsurplus] whiskers

[Dennis Monticelli]

The whisker problem bedevils us to this day.  In my field, the
semiconductor industry, we are trying to eliminate all lead from the
solders we use to coat our pins (for environmental reasons.  The new
plating compounds are mostly tin and have been found to be susceptable
to whisker growth.  In variable capacitors you can clear the path by
simply passing cardboard or similar stock through the plates, taking
special care to clear the paths where the rotor does not having a
natural clearing action. I doubt compressed air would catch enough
surface area to do anything nor would washing.

BTW, my industry has found that the tin whiskers can grow quite long,
more than the lengths described in the paper.  The tin whiskers will
grow over high quality plated areas, so the mention in the paper that
poor plating quality control is a root cause is not true.  The tin
whiskers we experience are pure and I supect the Cadmium whiskers
described in the paper are pure aliso.

Dennis AE6C

On Sun, Apr 6, 2008 at 4:18 AM, Gordon White <gewhite at crosslink.net> wrote:
> The first mention I saw of whiskers growing on plated surfaces was in a 1944
> (I believe) technical report in the Aircraft Radio Corp.  papers regarding
> service failures in the 8th AF in Europe of AN/ARC-5 type equipment. The
> time it took the whiskers to grow between variable capacitor plates was
> relatively short - on the order of a few weeks in high-altitude service.
>  - Gordon White
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