Hi Ron,
Even under the best of circumstances, Alloy 42 wets much less readily than Cu
(the dissolution rate of Ni into Sn is about 100x less than that of Cu), and
there is Alloy 42 used in Asia that cames (perhaps) from a south Korean mill
that is not solderable no matter what you do. HP ran into this and published
a paper on it.
Why on Earth would anybody use Alloy 42 in an QFP? That is about as bad as it
can get (much less compliancy than Cu leads).

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com

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