If you are talking outer space you are probably talking polyimide boards and other special materials, not the standard FR4. When we deal with the polyimide for space application, we do bake the boards just before assembly. This is treated as a special case, but polyimide is far from having the same chemistry as Ye old epoxy based FR4. Alain Savard, B.Sc. Chemical Process Analyst CAE Electronics Ltd. e-mail: [log in to unmask] -----Original Message----- From: Dieselberg, Ron [mailto:[log in to unmask]] We have been vacuum baking PWB's for about 15 or more years. There has never been a documented failure or problem with baking on our products many of which go into outer space. We normally bake before assembly, conformal coating and staking. When not in process the boards are stored in a dry nitrogen atmosphere. Baking has improved the quality of our vapor phase reflow operation and has reduced soldering and board defects. I suppose that if you "toast" the boards you could suffer some problems, but for us it has been nothing but improvements. Some of our customers have specified that the boards be pre-baked and the manufacturers of our conformal coatings have highly recommended it to prevent moisture entrapment. Until we encounter a problem or failure we will continue to bake as we have done in the past. Ron Dieselberg ############################################################## 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 ##############################################################