I saw a pretty bad case just a couple of months ago (mating contacts).
Tin was present on the Au plated contact surface, formed Sn/Au
intermetallics, which was cracking and delaminating from the base
material causing intermittence.
Vladimir
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Wednesday, February 06, 2008 4:36 PM
To: [log in to unmask]
Subject: Re: [TN] SAC on gold pins
From a connector reliability standpoint, SAC is mostly tin, and tin
oxidizes rather rapidly. So a SAC alloy wetting up onto the mating
portion of the connector contacts is still going to present the specter
of discontinuities and increased surface resistance, possibly even
sooner than a tin/lead solder will.
As far as I know, there is no difference in the acceptance criteria in
the standards for SAC alloy than for standard 63/37, assuming you are
required to meet the standards.
I don't know of any tin surface-to-gold surface issues, but I am always
open to being educated.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*
Sent: Wednesday, February 06, 2008 3:10 PM
To: [log in to unmask]
Subject: Re: [TN] SAC on gold pins
Hi Genny,
Well, that brings us to the famous "It depends."
It depends on which tin-to-gold issues you are referring to.
If you are talking about having solder on the mating surface, than I do
not think it makes much of any difference if it is SnPb or SAC.
Werner
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