In response to Dave Hoover's request concerning pcb warpage during BGA repair: Our analysis of BGA rework processes involved use of a 10"x12", 10 layer, .062" thick FR4 test board containing (12) PBGA 225 OMPAC devices. Several manufacturers' rework systems were evaluated, allowing comparison of rework processes utilizing both highly focused and wide area bottom side heating methods. We also experienced the problem of severe local area warpage during the reflow process, particularly where highly focused bottom heat was used. In some instances, the board surface at the center of the BGA dropped more than .015". Our best success dealing with the local warpage problem was achieved with the use of controlled wide area convective bottom side heating combined with adequate board support. The entire pc assembly was bottom heated prior to and during reflow with a fairly gentle thermal profile not exceeding 1.5 degrees C/sec. ramp rate. The profile's thermal events were precisely controlled with thermocouple feedback from the pcb, BGA, and top & bottom heat sources. The entire preheat/reflow cycle averaged 6 minutes, followed by cool down at room temperature. This process eliminated any significant local warping, but keep in mind it was a controlled test using a single side test pcb with only BGA's attached. Dave, I hope this info helps. Sounds like your customer is headed in the right direction. Dennis Measor Senior Manufacturing Engineer Allen-Bradley Co, Cleveland, Ohio [log in to unmask] Ph: 216.487.6170