Guess I should have been a bit more clear about "press fit connections". What Continental had was circuit boards with immersion tin finish, and they inserted press fit pins into those. Where the press fit portion of the pin entered the plated through hole, whiskers grew out of the hole and I think from the corners of the hole. Continental tried a number of pin configurations - "eye of the needle", and several more ways to get the gas tight fit in the hole - and as I remember, some difference in whiskering based on pin configuration.
I am talking more about this technology:
http://www.interplex.com/compliant/pressfit
I don't think the pins/sockets you show here would be tin plated and I don't see how they are pressed into the board.
Denny
-----Original Message-----
From: Steve Gregory <[log in to unmask]>
To: 'TechNet E-Mail Forum' <[log in to unmask]>; 'Dennis Fritz' <[log in to unmask]>
Sent: Mon, Oct 31, 2011 8:49 am
Subject: RE: [TN] Whiskers from Immersion Tin Finish?
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-----
rom: TechNet [mailto:[log in to unmask]] On Behalf Of Dennis Fritz
ent: Monday, October 31, 2011 8:15 AM
o: [log in to unmask]
ubject: Re: [TN] Whiskers from Immersion Tin Finish?
Continental Electronics presented a paper at the IPC Whiskers seminar in
chaumburg, IL concerning press fit connectors using immersion tin. Seems
he extreme compression exerted by the press fit operation can really cause
hiskers to grow from immersion tin plated boards. I think they uncovered
he problem by examining a filed failure of an automotive electronics
odule. Seems to me that on one occasion, even after they potted and cross
ectioned a connector, a tin whisker grew out of the surface of the cross
ection from the immersion tin in/near the through hole in the board. Now
hat's some long lasting compressive stress.
Denny Fritz
----Original Message-----
rom: Jack Olson <[log in to unmask]>
o: TechNet <[log in to unmask]>
ent: Fri, Oct 28, 2011 4:20 pm
ubject: [TN] Whiskers from Immersion Tin Finish?
've always been under the impression that the risk of Tin Whiskers was
stly from the portion of component leads that don't get wetted with
lder. (for example, a right-angle through hole connector may have exposed
ads ABOVE the solder joint area)
ow I'm being asked about the risk of whiskers from Immersion Tin finish in
eas that don't get soldered, like vias, or lands of components that don't
t populated. I haven't heard any of you talking about that, is this a
sk?
y first response was "naw, don't worry about it..",
t then I turned to IPC-4554 and see a whole section (3.9) on "Whisker
sues"
th Tables
d Beautiful Photographs
d advice on Measuring them,
d methods of Rating them,
d on and on...
ERIOUSLY?
sigh)
ack
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