We have been following the discussion of the warp "syndrome" for several weeks and have investigated all aspects of the construction, build, copper distribution, profiling presses, profiling ovens, and even evaluated a higher Tg material(180C).

We currently have temporarily acquired a horizontal rack for evaluation to bake the boards and the preliminary results appear very good. We are using a standard FR4 material (140C). The racks we have always used in the past were vertical with supports on top and bottom only. Any response or comments would be welcomed.