| 摘要 |
PROBLEM TO BE SOLVED: To eliminate open circuit or short circuit incident to formation of a through hole by hot pressing metal foils having two layer structure of a copper layer and a different metal layer to the opposite sides of a resin board, making a through hole in the integrated resin board and then removing the different metal by etching. SOLUTION: A metal foil 4 having two layer structure of a copper layer 2 and an aluminum layer 3 for forming a wiring layer is hot pressed to the surface of a board 1 with the copper side directing toward the insulating board 1 and a through hole 5 is made in the integrated board 1. Subsequently, the aluminum layer 3 is dissolved by an aqueous solution of sodium hydroxide and removed to expose the copper layer 2 and an electroless plating layer 6 is formed on the wiring layer and the inner wall face of the through hole 5 followed by formation of an electrolytic copper plating layer 7. Since burrs and residual carbon are removed simultaneously with foreign metals, open circuit clue to defective plating around the through hole or inter-wiring short circuit due to carbon does not take place in a printed wiring board thus obtained. |
