PURPOSE: To make possible a multitude of perforating treatments for through hole at one time by a method wherein a metal plate is made to expose in parts which correspond to a through hole part, the exposed metal plate is chemically removed and a through hole is formed to perform a through hole connection process.
CONSTITUTION: Metal foils 3 are respectively bonded on both surfaces of a metal plate 1 via resin layers 2. Then, the foils 3 of parts which correspond to a through hole part are removed, the exposed layers 2 are chemically removed with a sulfonic acid and the like and the plate 1 is made to expose. The exposed plate 1 is chemically removed and a through hole 6 is formed. The hole 6 is filled with a resin 7 and a hole of a diameter smaller than the aperture diameter of the plate 1 is mechanically perforated in the hardened hole filling resin 7. A plated film 9 is formed on the wall surface of the perforated hole, the metal foil parts on both surfaces of the plate 1 are connected to each other and an external layer wiring 10 is formed. Thereby, lots of the through holes 6 for through hole can be formed at one time without using a drill, the latter process can be smoothly treated and a decrease in cost is brought.
INADA TEIICHI
NAKASO AKISHI
