Our PCA house currently bakes all of our PCBs before assy. Our boards are typically 16" X 13". The boards are placed vertically in a rack that holds them by just the bottom edge that has a V-score breakaway. They are in there for 2.5 hours @ 200-210 deg F. We had a batch of boards that warp and twisted after the above mentioned bake. The PCA and PCB house are pointing fingers at each other as to who is at fault. So far it has been only one date code that this has happened to. Each PCB is one up on a panel from the PCB house due to its size. The PCB vendor claims that in talking to other PCA houses in their area, the boards should not be baked vert. in a rack because it is a hit or miss as to whether or not the boards will twist during the bake. The claim is that the boards should be baked horiz. stacked on top of each other. My question is: What is the correct method of doing a pre-bake of the PCBs to remove moisture prior to assy, if there is one? Best Regards, Michael Forrester Sr. Manufacturing Engineer LeCroy Corp --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------