This question comes up a lot, and my recommendation is O.K. for prototype,
not O.K. for production.  You hit one issue with dissimilar metals where
silver and tin don't form an acceptable couple.  You also don't form the
intermetallic, and over time, the oxide on the Sn will form, resistance will
increase, adhesion strength will decrease.  Of course, the operating
environment and reliability expectations need to be considered

Glenn

-----Original Message-----
From: Dan R. Johnson [mailto:[log in to unmask]]
Sent: Wednesday, April 23, 2003 1:04 PM
To: [log in to unmask]
Subject: [TN] SOLDER/EPOXY REACTION


I have a customer who is trying to attach our SMT part to their hybrid
assembly using silver fill epoxy. We use a  lead free alloy (Sn 96.5/Ag
3.5).
Any body have any experiences in this area. The customer (actually the CM)
is worried about dissimilar metals and long term reliability, should they?
Thanks,
Dan

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