To epochally improve production efficiency of a double-sided flexible printed circuit board (for example, a double-sided COF) of a high-density pattern.
Conductivity is given to the inner wall of a through hole 15 or a blind via hole 16 on a flexible copper foil laminated sheet 10, where a copper foil layer is laminated on both the surfaces of a base film 11. On one side of the copper foil laminated sheet, where the conductivity is given to the through hole or blind via hole, a plating shielding film 30 for preventing plating is formed. On the other side of the copper foil laminated plate whose one side has the formed plating shielding film, a one-side plating layer 20 having a specific thickness is formed by copper plating. The plating shielding film on one side is removed. A required specific printed circuit board is formed in a copper foil layer on one side, that on the other side, and a one-side plating layer each.
Tetsuo Kanamoto
Koji Hagiwara
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