Bretton There is no such thing like brittle fracture of eutectic tin-lead solder at temperatures above 0°C. The material creeps so fast that there is no way to reach any yield strength. I believe that good old Coffin-Manson is still the best model to describe the low cycle fatigue ( creep ) of SnPb solder. In our estimations the Coffin-Manson exponent is 1.4 - 1.7 for pure grain-boundary sliding. Actually I had a little paper in the IEEE Transactions on Components, Packaging and Manufacturing Technology January 99. But as Werner said, you are going to open a Pandora Box. Be aware of the bugs in there. Feel free to ask more. Best regards Guenter ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################