Hi Darrel,
You received excellent advice from Günter. I also would like toi direct you to
the information contained in IPC-SM-785, "Guidelines for Accelerated
Reliability Testing of Surface Mount Solder Attachments" and IPC-D-279,
"Design Guidelines for Reliable Surface Mount Technology Printed Board
Assemblies".
While extrapolation of data to different loading conditions can indeed be
dangerous, you would not go wrong using the model in the IPC documents as long
as you heed the stated caveats (I know, I developed both the model and the
caveats based on empirical results). Of the parameters you mentioned, joint
size (height only) and material CTE(s) are primary influences on reliability
(as are component size, delta-T, and lead stiffness), whereas solder
composition, pad (solder joint fillet) size (crack propagation-depending),
SMD/NSMD (solder mask defined/non-SMD) stress concentrations, and others are
second-order influences.

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]

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