In a message dated 04/24/98 18:05:45, Heidi Jones wrote: >Hi Werner, > >We use both, depending on the test specification, so I am curious, how do >the damage and/or failure mechanisms differ between thermal cycling and >temperature cycling? Hi Heidi, There is, of course, no difference between thermal cycling and temperature cycling; however, there is a huge difference between thermal/temperature cycling where the T-ramps do not exceed about 30C/minute and T-shock. The prime difference between the two is, that T-schock sets up transient thermal gradients that cause component and substrate warping, thus loading solder joints in tension; whereas T-cycling is slow enough to avoid warpages not occurring in product use and the solder joints are loaded in shear dur to the expansion mismatch between component ans substrate as they would be in most applications. 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] ################################################################ TechNet E-Mail Forum 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 <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################