Isn't this stuff supposed to have been baked already during manufacture = of the cores? Alain Savard, B.Sc. Chemical Process Analyst CAE Electronics Ltd. e-mail: [log in to unmask] -----Original Message----- From: Bob Dube=20 Subject: Re: [TN] laminate stress relief Stress releif baking needs to be done above the Tg for the material. = Most would hold at that temperature for 4 hours min. The cool down rate is critical because of the various CTEs of the laminate constituents = (glass, epoxy, copper). Somewhere around 4 deg/min F back thru the Tg is = usually what's recommended. Bob Dube -----Original Message----- From: Timothy Reeves=20 Subject: [TN] laminate stress relief board fabs: what (if any) baking of incoming core material do you do to minimize movement of layers. We try to have the material at 250=B0F for = one hour based on what someone told us quite a while back. Without going = through a big DOE, I'd like to ascertain if that's enough. Timothy Reeves ############################################################## 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 Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################