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Date: | Fri, 25 May 2007 15:26:16 EDT |
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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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