Hi George,
I am in full agreement with everything you said.
The statement, that Ag-embrittlement might be worse than Au-embrittlement is 
more anectotal than hard-data-based—it comes from the SJ failures at 
IBM-Austin with TI PLCC in1981/82 that led to the formation of the IEEE Compliant Lead 
Task Force chaired by Jack Balde. What happened there is that the components 
literally fell off the PCBs during bed-of-nail testing—we had never seen quite 
the same thing with Au-emrittlement, but that does not mean it cannot be.
I cannot comment on the SMART paper, because I do not know it.
For the IEEE CLTF issue, the problem was definitely Ag-embrittlement with Ag 
displacing the Pb but not the Sn for about 1/3 the SJ thickness—that work was 
done by Dimitri Grabbe, tech. director of AMP; and the failure mode was not 
interfacial but had the same material on both fracture surfaces.



Werner



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