| 摘要 |
<p>PURPOSE:To enhance reliability by eliminating a thin part, a disconnection, a short circuit and the like of a circuit by a method wherein a wiring part of a board is formed as a three-layer structure and a signal line is wired over two layers. CONSTITUTION:A circuit pattern is formed on a second conductor layer 16 of a both-sided copper-clad laminated board; an adhesive sheet 14 and a one- sided copper-clad laminated board 13 are loaded on it so as to face a first conductor layer 15 upward; these are laminated and united. Then, a part from the first conductor layer 15 up to a halfway part of an insulating layer 12 between the second conductor layer 16 and a third conductor layer 17 is buckled; a U-shaped part 18 is formed; a through hole 19 which connects the individual conductor layers is formed. Then, a whole substrate is panel-plated; circuit patterns are formed on the first and third conductor layers 15, 17 by using a solder resist method; after that, bonding pads 20 for semiconductor use are exposed from the upper-side face of the board at peripheral parts of the U-shaped part. Thereby, problems such as a disconnection, a thin part and the like of the circuit pattern are eliminated; high reliability is realized.</p> |
