A PWB fabrication company I worked for years ago left a rack of boards in a sulfuric acid bath over lunch. The operators figured sulfuric acid removes copper oxides so it would be a good holding bath. The resin was softened and swelled. In assembly, or heating with a soldering iron, the resulting out gassing produced what looked like mini volcanic eruptions from which copious amounts of white smoke issued. No degree of baking could prevent the out gassing. Paul Reid ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------