It looks like I need to defend that statement. Somewhere in my files is a an article comparing rate of change on soldered assemblies. When a fast rate of change was used, the assemblies survived. When a slow rate of change was used, failures occurred. All else being equal with respect to temperature limits and number of cycles. The explanation was at a high rate of change, the solder joints did not have the opportunity to "relax." I'm sure others can explain that better than me. So, my point is, a slow rate of change would be more effective at testing the solder joints than a high rate of change. I think we're all saying the same thing. Heck, I learned this from you guys! Glenn -----Original Message----- From: [log in to unmask] [mailto:[log in to unmask]] Sent: Monday, March 11, 2002 10:15 AM To: [log in to unmask] Subject: Re: [TN] Thermal Shock Hi Jim, In a message dated 03/11/2002 7:59:02, [log in to unmask] writes: >Glenn (or anyone else), could you elaborate on your statement that slow >rates of change affect solder joints more than fast rates of change. A: No, the statement is incorrect. The rate of change in temperature is more detrimental when high due to possible component/PCB warping. What is more detrimental is a longer hold times typically associated with slower heating rates and not T-shock. Werner Engelmaier Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 386-437-8747, Fax: 386-437-8737 E-mail: [log in to unmask], Website: www.engelmaier.com