Patent ID: 7666320
Filing Date: 2010-02-23
Classification: B23K,H05K,Y10T

Abstract:
1. A method of manufacturing a printed wiring board by machining a via by means of a laser directly through a copper foil of a copper-clad laminate in which the copper foil is clad on a base material resin, wherein machining said via is carried out by a process, in the following sequence, comprising: forming a copper oxide film on a surface of an outer layer copper foil pasted on an outer layer of said base material resin; laser machining to form the via through the outer-layer copper foil and base material resin, wherein an adherent substance derived from the base material resin is adhered to molten and scattered copper formed during the laser machining around an opening of the via; removing the adherent substance with an alkali aqueous solution to expose the molten and scattered copper while leaving a resin smear on the bottom of the via covering an inner-layer wiring; etching to selectively remove the molten and scattered copper with an etching solution containing member selected from the group consisting of (1) ammonium persulfate, (2) sodium persulfate, (3) ferric chloride, (4) ammonia and hydrogen peroxide and (5) ammonia and copper chloride, while leaving the resin smear on the bottom of the via and the copper oxide film on the outer-layer copper foil; and removing the resin smear on the bottom of the via by a de-smearing process after etching the molten and scattered copper.