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Date: | Tue, 14 May 1996 18:47:45 -0500 |
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Are all copper alloy leads and lead frames the same ? Are there
material and/or lead process differences (annealing, cold
work,etc..)that would make one method of fabricating Cu lead or lead
frame more susceptible to dissolution at high temps >+175degC with the
soldering alloy being high tin (similar to SN96) ?
SOLDERING PROCESS
A hand soldering process with soldering iron tips being at or around
850degF with 3 to 5 second dwell.
PROBLEM
The dissolution of metals appears to be occurring on some Cu leaded
parts fairly rapid while on others there appears to be little evidence
of this happening. It appears as though the component lead is
virtually disappearing.
All parts are chemically stripped and pretinned with Sn99 to prevent
the possibility of cross-contamination with Pb.
The solder joints are under thermal soak @ temps greater than +175degC
Any information on this subject would be appreciated.
Thanks,
D.Drake
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