Manufacturing method for a multilayer wiring board

Abstract

A multilayer wiring board is constructed of insulating substrates and circuit patterns formed thereon. A manufacturing method produces the multilayer wiring board by forming a mask on one surface of the multilayer substrate. The mask has apertures registered with blind holes and/or a through hole wherein the apertures have different diameters depending on the depths of the blind holes and/or the through hole such that the larger the depth, the larger the diameter. Etching is performed on the multilayer substrate corresponding to the smallest aperture using an abrasive powder having a particle size smaller than the diameter of the smallest aperture. Portions of the multilayer substrate are gradually etched corresponding to the other apertures using abrasive powders having particle sizes smaller than the diameters of the other apertures wherein the blind holes having the desired depths and/or the through hole are formed in the multilayer substrate. Accordingly, the blind holes having different depths and/or the through hole can be formed by using the single mask. Further, the required depths of the blind holes and/or the through hole can be obtained without unduly etching the bottom of the blind holes. A reliable electrical connection can be obtained between the circuit patterns in the different layers through the conductive films formed on the inner wall surfaces of the blind holes and/or the through hole.