Guys (and girls), Can anyone tell me whether or not polyimide boards need to be pre-baked before processing thru nitrogen reflow for solder melt? We are doing it, which of course means added expense. Is it really necessary? We bake at 110 C for four hours. Is there evidence which suggests that it is necessary. Thanks for any replies, Bill Mengers Northrop Grumman Corp. Baltimore, Md. ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################