We build boards for space and they must be bonded and riveted to rigid aluminum frames to withstand the environments. We currently specify the IPC-6012 requirements which are 0.75% bow and twist. There is a concern that we may need to specify 0.5% bow and twist to prevent 1812 and possibly 1206 ceramic capacitors from developing cracks after the boards are attached to the frames. With our boards, .75% translates to a maximum of 45 mils of bow and twist. Any thoughts on problem areas? The boards are normally .090 thick, 8-12 layers and polyimide. --------------------------------------------------- Technet Mail List provided as a free 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------