Dual-Ply Prepreg

Resin Flow

Hydraulic vacuum presses consolidate resin layers under controlled temperature ramps to fill structural gaps between etched inner layer features. Specifying dual-ply prepreg allows board designers to combine a high-resin-content fine glass style with a structural coarse glass style. Outer plies smooth surface topography while inner plies supply core rigidity, improving overall dimensional stability across thermal processing steps.

Differential resin flow between dissimilar plies prevents weave telegraphing on outer copper foils during final pressing operations. Vacuum cycle parameters must balance gel time against peak pressure to prevent excessive resin squeeze-out.

Thickness Stability

Nominated dielectric target dimensions experience local drift when asymmetrical inner layer copper distribution draws excess resin into high-density routing zones. Excessive resin displacement during dual-ply prepreg lamination alters local characteristic impedance along high-speed signal paths. Compliance limits for controlled impedance traces fail when total dielectric thickness varies by more than ten percent from baseline stackup modeling.