Hi Paul,
Your e-mail leads me to believe that I am walking in on an ongoing
conversation.
>What would the recommended or experienced alloys be ?
         What are you talking about?
>What papers/publications would be advised ?
         What are you talking about?
>Would this new alloys alter the existing reliability test guidelines (like
IPC-
>SM-785) to non applicability ;as most of the statistics were based on 63/37 ?
Seems you are talking about solders, maybe lead-free. The reliability test
guidelines are o.k., but some of the specifics may have to be somewhat
altered, because they are based on modeling the behavior of near-eutectic
Sn/Pb solders. Having said that, I need to point out that adequate
reliability data for lead-bearing solders other than near-eutectic Sn/Pb do
not exist either. Modifications to the model coefficients is only possible
with adequate data. However, the scarce data in existance for these solders
indicate factor of 2 differences from near-eutectic Sn/Pb fatigue; thus, the
errors introduced by different solders has been small so far. This may change
with lead-free solder alloys.
Neither the physics-of-failure nor the statistics for solder joint failures
will change, however.
Given the current tight (to none) resources at the OEMs and industry labs, I
am not very hopeful that the necessary work to develop models for the other
solders will be undertaken in the forseeable future.
>Would any other IPC ; MIL ; IEC standards require reconsiderations ?
Well, that depends, I am sure (not much help here).

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com

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