Jeff -

   From experience we have found that un-balanced
stack-ups can cause warpage to the extent that
quad-flatpacks can not be attached, >0.010"/inch. 
   I assume from your message that you are faced with a
situation where you have 3 planes in a given board, 5v, 3.3v,
and ground. The recommendation  we have received in
laying-up this type of stack in a 6 layer board is:

Signal
Voltage
Signal - "filled with Ground"
Ground
Voltage
Signal

The "odd" plane lair should be balanced by filling the
"odd"signal layer with poured copper to help reduce built in
stress. Large copper areas additionally should be broken in
to hatched patterns (positive-image mesh) to balance the
copper area for platting.

I hope this helps.

Jeffrey McGlaughlin
BFGoodrich Avionics Systems Inc.
Columbus, Ohio 

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