Well, that's just the thing - is whiskering non-existent with lead in the
mix?  The article in the advanced packaging magazine said that lead had
nothing to do with reducing or eliminating whiskers, that tin could whisker
even when mixed with lead and they had a couple of pictures as examples.
Their premise was more about that better processes have reduced or
eliminated the whiskering and that is the only reason why we see less
whisker problems today.  They said that Tin should be considered a simple
drop in replacement for tin-lead.

I get a little concerned when someone seriously contradicts an organization
like NASA, not that NASA can't be wrong.  But it looks like NASA has thrown
a lot of money at the problem, so why haven't they ever come across the
problem of tin-lead having just as much propensity to whisker as straight
tin?

As far as the boards we received, I'm pretty sure they are a white tin, and
I'm sure that they would work fine for the uses they are designed, but it is
a concern when a co. just substitutes one process for another without
telling you.  It is questionable whether we will use that co. again.

-----Original Message-----
From: George Milad [mailto:[log in to unmask]]
Sent: May 14, 2001 12:10 PM
To: [log in to unmask]
Subject: Re: [TN] Pure Tin


Genny,
If your supplier has used immersion tin as a solderable finish; then you
should be able to assemble  the parts successfully.
After assembly the immsersion tin is disolved into the solder and becomes
part of the solder joint.  Immersion tin as such would cease to be part of
the finished product, and the probability of "Solder Whiskering" is non
existent.
I hope this is helpful.
George Milad
Shipley Ronal Inc

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