Hi Denny,
So, if I were to be building a wire harness with a tin plated Samtec contact
( http://www.samtec.com/documents/webfiles/cpdf/CC69X-XXXX-01-X-XX-MKT.pdf
), I should be concerned?
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dennis Fritz
Sent: Monday, October 31, 2011 8:15 AM
To: [log in to unmask]
Subject: Re: [TN] Whiskers from Immersion Tin Finish?
Continental Electronics presented a paper at the IPC Whiskers seminar in
Schaumburg, IL concerning press fit connectors using immersion tin. Seems
the extreme compression exerted by the press fit operation can really cause
whiskers to grow from immersion tin plated boards. I think they uncovered
the problem by examining a filed failure of an automotive electronics
module. Seems to me that on one occasion, even after they potted and cross
sectioned a connector, a tin whisker grew out of the surface of the cross
section from the immersion tin in/near the through hole in the board. Now
that's some long lasting compressive stress.
Denny Fritz
-----Original Message-----
From: Jack Olson <[log in to unmask]>
To: TechNet <[log in to unmask]>
Sent: Fri, Oct 28, 2011 4:20 pm
Subject: [TN] Whiskers from Immersion Tin Finish?
I've always been under the impression that the risk of Tin Whiskers was
ostly from the portion of component leads that don't get wetted with
older. (for example, a right-angle through hole connector may have exposed
eads ABOVE the solder joint area)
Now I'm being asked about the risk of whiskers from Immersion Tin finish in
reas that don't get soldered, like vias, or lands of components that don't
et populated. I haven't heard any of you talking about that, is this a
isk?
My first response was "naw, don't worry about it..",
ut then I turned to IPC-4554 and see a whole section (3.9) on "Whisker
ssues"
ith Tables
nd Beautiful Photographs
nd advice on Measuring them,
nd methods of Rating them,
nd on and on...
SERIOUSLY?
(sigh)
Jack
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