| 摘要 |
PURPOSE: To obtain a high-density multilayer printed wiring board by forming a plurality of independent circuits with one through hole. CONSTITUTION: Conductor layers 1 with large and small diameters of a through hole with steps are split into a plurality of parts in circumferential direction and are independent and a wiring circuit 1b and an inner-layer circuit 1e are connected independently and separated, thus forming a through hole 1d with steps having a plurality of independent circuits. First, a hole with steps is formed, the cross core is positioned and embedded and then through hole plating is performed. Then, the cross core is eliminated. Then, a sensitized resin paint film is formed, a specific mask film is allowed to contact for exposure, the exposed part is eliminated, and then an exposed conductor layer 1 is etched. After that, a positive-type sensitized resin film is released and eliminated, thus obtaining a multilayer printed wiring board with the through hole 1d with steps having a plurality of independent circuits. |
