Check the TechNet archives, there must have been 50 messages about the TSOP 
Alloy 42 solderability problem in the last year.
 ----------
From: Tom Monico
To: [log in to unmask]
Subject: [TN] Solderability od alloy 42
Date: Wednesday, February 18, 1998 12:15PM

Hi all,
 
We've noticed different solderability performance of alloy 42 TSOP lead 
frames vs. copper 194 lead frames on an electroless nickel/immersion gold 
SMT finish. Alloy 42 exhibits reduced solderability at lower reflow 
temperatures. However, even at 218 degrees C, the alloy 42 lead frame still 
does not yield the bond pull strength of the copper lead frame.
 
Any comments or observations would be greatly appreciated.
 
Tom Monico
MicroVia, Inc. 
 
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