Could tg 170 material adsorb enough moisture in 2 weeks at 20C and 70Rh to cause delamination in a 1.5mm thisch 4 layer PCB? The bake out time will vary with the thickness of the PCB and the number of layers i.e. 1mm double sided vs 2.3mm 24 layer will have signifactaly different paths for the mositure to escape. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------