Hi Steven, The only study that did this extensively is reported on in IPC-TR-579 —"Round Robin Reliability Evaluation of Small Diameter Plated Through Holes in Printed Wiring Boards." For the same delta-T, there is pretty good correspondence. Also, for bare PCBs, it does not matter whether you change T's fast [T-shock] or more slowly, since for a symmetrically built PCB T-gradients do not affect the loading stresses [in contrast to assemblies]. Also, IPC-TR-486 —"Report on Round Robin Study to Correlate Interconnect Stress Test (IST) with Thermal Stress/Microsectioning Evaluations for Detecting the Presence of Inner-Layer Separations" provides good correlative information. Werner --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------