| 摘要 |
<p>PURPOSE:To form a recessed groove having a flat bottom in contact with an inner layer copper foil surface without damaging the inner layer copper foil by forming a resist film in advance at a section of a bottom of a recessed groove. CONSTITUTION:A photosensitive resist film is laminated on a surface of an insulating board 1 and a resist film 4 is formed at a recessed groove formation section on a circuit pattern 3 through exposure and development. Then, a plurality of prepregs 5 and a copper foil 6 whose one side is roughened are provided to both sides of the insulating plate 1, and heated and fixed by pressure to form a lamination board 7. Then, an opening is drilled at a specified position of the lamination board 7, a through-hole 8 is formed, and a recessed groove 9 which attains a resist coat 4 from a surface of the lamination board 7 is formed by using a drill bit. After residue of the resist coat 4 is swelled and removed, or, smear 10 and resist residue 11 are oxidized and removed by plasma consisting of a mixture gas of oxygen and fluorine, then, copper plate 12 is applied all over including an inner wall of a through-hole 8 and an inner wall of the recessed groove 9 of the lamination board 7.</p> |
