In reference to cross plying lamination of multilayer boards:

Crossplying has been used successfully by crossplying the B-stage with the
internal layers in order to balance out dimensional change in the X and Y
planes.  Crossplying layers with each other most often leads to warping,
twisting and misregistration.  With the ability to compensate artwork
differently in the X and Y directions and each layer independently,  the need
for crossplying is very limited and probably should only be used where an
unsymmetrical design may require an unsymmetical crossply construction to
compensate for a warp that cannot be corrected any other way.

Phil Hinton
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