Hi J-P & All,
So far, I have not seen any evidence of LF-SJ failures, being significantly 
different from SnPb-SJ failures; only time will tell. J-P concentrates on SJs, 
and there our experience as consultants appear to coincide.
 
However, I have seen a significant increase in PCB failures from the higher 
LF-soldering T's. Of course, using 'proper' laminates [lower CTE, higher Tg, 
higher Td, higher $$$] is likely to solve those issues [see Engelmaier, W., “
Printed Circuit Board Reliability: Needed PCB Design Changes for Lead-Free 
Soldering,” Global SMT & Packaging, Vol. 5, No. 8, September 2005, pp. 41-44], but 
the higher costs and the only slowly increasing awareness of the issues, will 
result in many more PCB failure issues.

I see the LF-reliability issues to be much more important on the PCB side 
than the SJ side. Fortunately, it is the soldering processes that cause the 
failures; thus, field failures should not significantly increase since the failures 
should show up at functional testing/burn-in.

Werner

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