Hi Dave, You give me too much credit, I do not the deformation work or specifically deal with the underlying deformation mechanism(s) of solder; I am more in league with John Hagge who took some of my work on flex circuits and copper foil and utilized it for solder. While I need to be concerned about the deformation mechanism(s), it is only insofar as they limit the applicability of practical first-order reliability estimation models. For the underlying deformation mechanisms the credit for the current understand and perhaps hope for future improvements need to go to people like Grossmann, Frear, Solomon, Fox, Knecht, Shine, etc. Lau also does not work on deformation mechanism(s); he uses FEM, neglecting creep and stress relaxation, to determine localized stresses and strains, and than applies Norris-Landzberg even though that model was discredited by other workers at IBM (Shah, et. al.) and does not account for the all-important dwell time that limits full stress relaxation in most accelerated tests. Werner Engelmaier Engelmaier Associates, Inc. Electronic Packaging, Interconnection and Reliability Consulting 23 Gunther Street Mendham, NJ 07945 USA Phone & Fax: 201-543-2747 E-mail: [log in to unmask] *************************************************************************** * 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] * ***************************************************************************