Patent ID: 7080448
Filing Date: 2006-07-25
Classification: H05K,Y10T

Abstract:
1. A method for fabricating printed circuit boards comprising: (a) forming a first layer of conductive metal to transfer plate; (b) applying a layer of tin or a layer of eutectic tin alloy over said first layer; (c) removing selective portions of tin layer by laser ablation thereby exposing corresponding portions of the underneath metal layer; (d) removing portions of the conductive metal layer not covered by tin layer; (e) removing remaining thin layer chemically and leaving the circuit pattern on said transfer plate; (f) forming a thin layer of conductive metal on the surface of said transfer plate and said circuit; (g) laminating the transfer plate to a layer of semi-cured prepreg with circuits facing to said prepreg; (h) removing said transfer plate, etching away thin covering conductive metal layers, and leaving circuits inlaid in the surface of the dielectric substrate; and (i) drilling holes through the board selectively and forming metal along the walls of the holes to interconnect circuit lines on both sides of said substrate.