Patent ID: 8366903
Filing Date: 2013-02-05
Classification: H05K

Abstract:
1. A method of manufacturing a printed wiring board having a surface copper layer on the surface of the wiring board, an innerlayer copper layer, and an insulating layer separating the surface copper layer from the innerlayer copper layer, said method comprising: forming a laser absorbing layer on the surface of the surface copper layer, the laser absorbing layer being a copper oxide film; irradiating a laser to the laser absorbing layer to form a via reaching from the surface copper layer to the innerlayer copper layer; performing an electrolytic etching to remove unnecessary machining by-products generated around the via of the surface copper layer during said irradiating of the laser to form the via, the electrolytic etching being performed using an alkaline etching solution containing a material selected from a group consisting of (i) ammonium sulfate and sodium chloride, (ii) sodium sulfate, and (iii) potassium sulfate; and removing the laser absorbing layer.