We recently experienced the same type of problems with 20 mil TSOP
packages that had a lead frame made from a material called Alloy42.
When the vendor switched lead frames to copper all of our problems went
away.  I wonder what the lead frame material is on your fine pitch QFP
is?
 ----------
From: [log in to unmask]
To: [log in to unmask]
Subject: Electroless Nickle and Immersion Gold
Date: Thursday, July 10, 1997 9:41AM


Hi All,
Recently I heard of Solderability issue and lead fracture on fine picth
QFP
(16 mils or
less) during vabiration test on the PWB with Electroless Nickle and
Immersion
Gold finish (100u-200u of Nickle and 3u-5u of gold) , couple reason was
mention one
being the flux used during the assembly and another was the Nickle
passivation on the
PWB before assembly.
Is any of you have any experience with this problem and if you do, what
you
have done to
correct the problem. Also I am interested on all the good things you can
tell me about
this finish type.
Thanks.

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