We build boards for space and they must be bonded and riveted to rigid aluminum frames to withstand the environments. We currently specify the IPC-6012 requirements which are 0.75% bow and twist.
There is a concern that we may need to specify 0.5% bow and twist to prevent 1812 and possibly 1206 ceramic capacitors from developing cracks after the boards are attached to the frames.
With our boards, .75% translates to a maximum of 45 mils of bow and twist. Any thoughts on problem areas?
The boards are normally .090 thick, 8-12 layers and polyimide.