A proposal has been made that all our recently designed surface mount printed circuit board assemblies be subjected to the following thermal cycling process: 1) Heat chamber to +71 degrees C as rapidly as chamber allows (but not to exceed 15 degrees C per minute). 2) Dwell at +71 degrees C for 2 hours. 3) Ramp temperature down as rapidly as chamber permits to -40 degrees C (but not to exceed 15 degrees C per minute). 4) Dwell at -40 degrees C for 2 hours. 5) Ramp temperature from -40 degrees C to +71 degrees C as rapidly as chamber allows (but not to exceed 15 degrees C per minute). 6) Conduct the above +71>-40>+71 thermal cycle 6 times. 7) Retest PCB assemblies. Note: No power or signal is applied to units during thermal cycling. View #1: The thermal cycling described above will tend to screen out those assemblies with defective components and/or workmanship faults--including those involving solder connections. It will help identify likely infant mortalities and assemblies likely to fail prematurely in field operation. View #2: The thermal cycling described above is likely to create more defects than it identifies. The cost of performing this screening process outweighs its benefits. Our electronic equipment is generally designed and qualified to operate from -40 degrees C to +70 degrees C. I would appreciate any references to personal experience or literature which would help determine whether View #1 or View #2 is more credible. Thanks for any replies. ############################################################## 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 <your full name> 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 ##############################################################