You are right, Werner, after weeks of working with the advanced calculation (kilograms of paper!) our specialist gave us the glorious message: "they took that way, or possibly the other way". The later was from Asterix when Obelix was asked by a centurion what way the prisoner escaped. My metaphor was maybe a little exaggerated, but what I mean is that you get the information about the direction, but hardly the exact number of kilometers to the goal. However, that indication is many a time enough to avoid disastrous designs./Ingemar
Hi Jason,
Get yourself a copy of IPC-D-279, Design Guidelines for Reliable Surface
Mount Technology Printed Board Assemblies, and read Appendix A so you know
what is important for solder joint reliability. Appendix A also gives you a
solder joint reliability model. Be careful with FEM on solder joints, because
I am quite sure you do not have the necessary property information. There are
in infinite stress-strain diagrams dependent on temperature and strain rate,
as do the yield and ultimate strength, the modulus of elasticity and the
ductility.
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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