Hi Werner, many thanks for your response. You made some good points here. I repeated the details of the att. memo in my note. I supose what I am really talking about is a stress screen on populated cards, to accelerate the Early Life part of the Bath Tub curve and therefore improve the overall reliability figure. I think the 'experimental' results would really be 'experience' results and come from anyone who had previously implemented this Bathtub acceleration, OR who had implemented one of your ESS's to find a problem. Perhaps the profile used SHOULD take the worst possible useage conditions and add some overhead for 'Gaurdband'. Thanks again Werner. Any more input from the TechNet now I have clarified my problem? Cheers, Steve. ([log in to unmask]) ############################################################## 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. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################