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