| 摘要 |
PROBLEM TO BE SOLVED: To make the thickness of a thin-film conductor layer nearly uniform on the entire internal surface of a through hole for reducing a transmission loss in a signal, to prevent the tin-film conductor layer from being thinned and cutout or the like from being easily generated at both opening end sections, since the internal surface of the through hole makes an acute angle with the main surface of an insulating board at both the opening end sections of the through hole, and to prevent burnout and continuity fail in the thin-film conductor layer. SOLUTION: This wiring board has the insulating board 1, a thin-film wiring conductor layer 2 formed on the surface of the insulating board 1, and the thin-film conductor layer 3 deposited onto the internal surface of the through hole 4 formed on the insulating board 1 for connecting to the thin-film wiring conductor layer 2. In the through hole 4, the width of the opening on both the main surfaces of the insulating board 1 is different, a portion from one opening to depth being 1/2 to 2 times larger than the width of the opening is set to a cylindrical section 4a, and at the same time the width gradually widens from the cylindrical section 4a toward the other opening.
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