Dave, There has been incidents of solder joint fatigue failures in avionics, space, automotive, medical, computer, telecomm applications, etc..., involving LCCCs, PLCCs, QFPs, TSOPs and others. Of course, these incidents are not much talked about. Sources of problems went from a design being unfit for a a given application (high ramp rates resulting in overstress, lack of compliance or too large of a CTE mismatch) to not enough solder, gold embrittlement etc... most of these problems could have been avoided by upfront design-for-reliability work (as opposed to "one of those after-the-fact dilemmas"). I also wonder about all those NTFs (no-trouble-found) where the board is just thrown away without failure mode analysis?? On the subject of life predictions, there are several engineering approaches to choose from, each with their own scope of application, strengths and weaknesses. Coffin-Manson is a subset of Morrow's generalized fatigue law where the fatigue life is correlated to cyclic inelastic strain energy. Strain energy is used in: IPC model for leaded assemblies, Darveaux's model (chap 13 in Lau's Ball Grid Array Technologies), "Solder Reliability Solutions" (Clech, Proceedings, SMI'96, p. 136) and others. For SMT assemblies, the strain energy approach has been found to work better because it accounts for the entire stress/strain cycle (hysteresis loops). The Coffin-Manson approach is strain driven only (but it works in some cases). National labs are also working on 3D finite-element models with microstructure evolution, which will provide detailed fundamental insights in solder fatigue. Last I heard, computations were being switched from a Cray (where it takes one week to get the first couple of hystereris loops) to a massively parallel machine. Jean-Paul ________________________________________________________________ Jean-Paul Clech EPSI Inc., P. O. Box 1522, Montclair, NJ 07042 - USA tel: +1 (201)746-3796 fax: + 1 (201)655-0815 Home page: <A HREF="http://members.aol.com/Epsiinc1/index.html">http://members .aol.com/Epsiinc1/index.html</A> - click on the above or copy: http://members.aol.com/Epsiinc1/index.html __________________________________________________________________ *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************