Friends:

I have a 6 layer board that warps.  The R&D group tells me its a
Manufacturing problem. I'm not so sure.

Details:
.062" Thick NEMA FR4
Stack: (Trace/Gnd/Trace/Trace/Power/Trace) w/1/2 oz copper clad.
R&D group tells me the layers are balanced from the center of the stack
out.

What should Manufacturing be doing to prevent these boards from
warping?  Or is the only solution a higher temperature
FR4 material that adds cost to the board.  Could it be a problem with
the board house. Please advise.

Regards, Chris

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