I do not quite agree with the baking of boards to remove warp. Baking = can be used to flatten a board... temporarely. As soon as the board meets = another heat cycle above Tg, the stress in the board will be relieved again , bringing the board back into the warped/twisted position... Since this = may accour during relow or wave soldering, it may slightly shift coponents = at that time. If you find this may be a problem be very careful. I have = not tried the SLOW cool down method however and it might work. Alain Savard, B.Sc. Chemical Process Analyst CAE Electronics Ltd. e-mail: [log in to unmask] -----Original Message----- From: Bob Dube <SNIP/> If however, a construction is largely well balanced and some warpage is still for whatever reason noted a bake cycle may = very well help. The trick would be to apply light pressure to flatten (we = use steel weights), bring the temperature of the panels up past the Tg = (glass transition temp) hold at temp for several hours, and then allow for a = very slow cool down under weight back through the Tg. A cool down of less = than 4 =B0 F per min. should help in avoiding re-introducing the sort of = stresses which will lend to warpge. This is a key component in the lamination process of multilayer boards. Slow, gentle cool down. </snip> Bob Dube ############################################################## 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 ##############################################################