Hot-press processing includes conventional lamination, cold pressing, quick lamination, and B-stage pre-baking.

Hot pressing bonds coverlay or stiffeners fully to the board. Adhesive systems include pressure-sensitive and thermosetting types.

Temperature, pressure, pressing time, and the arrangement of auxiliary layers are controlled to achieve good adhesion

while minimizing pressure marks, bubbles, wrinkles, adhesive overflow, and broken traces.

1. Layer arrangement: see the illustration above.

2. Auxiliary materials and their functions:

(1) Silicone-aluminum foil: heat transfer and venting.

(2) Fiberglass fabric: separation and release.

(3) PTFE (Teflon) film: dust protection and prevention of pressure marks.

(4) Teflon-coated steel plate: heat transfer and venting.