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 [log in to unmask]