Ken, You didn't say if the board is a multilayer, if so, you may need to check lay-up construction for metal distribution. Uneven stackup can be a major cause of warp. We are a pcb vendor and we do not regularly 'dewarp' boards. Anne Ledger EMDS, Inc. > -----Original Message----- > From: Ken Nevius [SMTP:[log in to unmask]] > Sent: Tuesday, January 19, 1999 4:33 PM > To: [log in to unmask] > Subject: [TN] Bowed Boards > > We have been seeing boards come off our reflow oven with bow and > twist > that exceeds IPC specs. Our vendor insists that we are the only > customer that complains about this. We had our reflow oven > calibrated > and it looked fine. The only thing about the profile that may be > suspect is the cooling rate may be a little too fast. According > to the > vendor, they put all of their boards through a de-warping process. > The vendor has tweaked their de-warping process to cool slower in > an > effort to make the problem go away. > > My question is: This is our first bout with warping, what should > we be > looking at for a cause? Is it normal for a pc board vendor to > have to > de-warp boards? > > > Regards, > > Ken Nevius > Veeder-Root > Altoona, Pennsylvania > > ################################################################ > 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 ################################################################