| 摘要 |
PURPOSE:To realize a printed wiring board provided with through-holes which can be connected together by a method wherein a plating layer formed on the inner wall of the through-hole is split into pieces by an insulator. CONSTITUTION:A copper foil 3 is pasted on both the sides of an insulating layer 2 for the formation of a copper-plated laminate board, through-holes are provided to the laminate board 1 partially overlapping each other to form a primary hole (through-hole) 4, a copper plating layer is formed on the inner wall of the primary hole 4 and the surface of the copper foil 3 through electroless copper plating, and furthermore a copper plating layer 5 is formed on the upside of the copper plating layer. The copper plating layer 5 is formed uniform in thickness, a photosensitive etching resist, film 6 is laminated thereon, exposed to light, and developed, and the unexposed and undeveloped film 6 is removed, and the disused copper plating layer 5 and the disused copper foil 3 are removed. Therefore, the film 6 left unremoved on a circuit pattern is separated off, and the edge of the overlap of the primary hole 4 where through-holes overlap each other is cut off through a secondary hole processing, whereby four insulating sections 9 are formed, and four circuit patterns P on each side of the laminate board 1 are connected to each other. |
