Bill- I agree with Steve Gregory. If you had a history of moisture absorption problems then I would. Bear in mind that polyimide generally saturates at 3-5% water vapor at STP. Thus, even a factory floor at 50% RH will allow for the poly-i to saturate eventually. Hopefully, your are getting the boards dry-packed, and they are not opened from the dry pack until just prior to stuffing. If you have the boards opened for any appreciable time before stuffing (say 3-4 hours) then you may want to orchestrate an experiment to see what, if any, difference there is in defectivity between a newly opened package and one that's been sitting out for a couple of hours. ANything longer than 8 hours I would definitely bake. > Bill Davis, Ph.D. > Diamond Multimedia Systems > Senior Scientist > Tel. 408.325.7868 > Cell. 408.888.5650 > e-mail: [log in to unmask] > > -----Original Message----- From: Mengers, William D. [mailto:[log in to unmask]] Sent: Thursday, April 08, 1999 1:02 PM To: [log in to unmask] Subject: [TN] Baking of polyimide boards 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 ################################################################ ################################################################ 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 ################################################################