Daan You've already heard that the boards will likely warp when they go above Tg (such as during reflow). But I'd have another concern with these. You've already been told the material was not manufactured properly. What assurances do you have that whatever is wrong with the material will not manifest itself in some other way. For instance if the material is prepreg is defective because the thicknes of resin coating on the glass is uneven, what other implications, beyond warpage, does that mean in your final product? Mike McMaster RF Product Engineer Merix Corporation 503-992-4263 > ---------- > From: d. terstegge[SMTP:[log in to unmask]] > Reply To: TechNet E-Mail Forum.;d. terstegge > Sent: Thursday, May 22, 2003 1:13 AM > To: [log in to unmask] > Subject: [TN] Bad laminate and warped board > > Hi Technet, > > I recently received some boards that were warped outside the IPC > specifications and I complained about it to the manufacturer. Their > answer is that the problem was caused by variations in laminate and > prepreg, where the operater didn't do the prescribed > material-inspections. > They will rework the boards by applying pressure at a temperature > higher then Tg, to release the stresses in the material. > > Some questions: > Whats' the proper way for a bare board manufacturer to control the > quality of laminates and prepregs with regards to flatness ? Is it > common practice to rely on an incoming inspection ? > If a board is flattened, will it remain flat after soldering ? I know > that with an unblanced design the problem will always re-occur, but I'm > not sure what will happen when it's the laminate-quality that caused the > problem. > > Daan Terstegge > Thales Communications > Unclassified mail > Personal Website: http://www.smtinfo.net > > --------------------------------------------------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8e > 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/html/forum.htm for additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > ----------------------------------------------------- > --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------