Hi Kenneth,
By definition, 'Burn-In' is a functional test typically at worst-case 
operating conditions. No significant deterioration of the good solder joints need to 
be expected.
In contrast, 'Screening Procedures" [ESS] are designed to produce failures in 
latent defects in-house, so they do not occur at your customer. While some 
loss of life of the solder joints can be expected depending on the procedure 
used, it still should be no more than about 10%.
I have never heard of "leaching of solder joints" under any test condition.
It would be useful to provide details as to what you are doing in your 
"burn-in" and what it is you are observing.

Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com



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