Patent ID: 7264848
Filing Date: 2007-09-04
Classification: C23C,H05K

Abstract:
1. A process for electroless gold plating, comprising forming a gold layer, by electroless gold plating, on a surface of a pad for mounting a solder ball, which pad comprises an end part of a wiring pattern, wherein the gold layer is formed on a metal layer comprising Ni—P on the pad exposed at a bottom surface of a concave portion that is opened in a resinous mask layer covering one surface of a substrate, wherein the metal layer is formed on the pad using an electroless nickel plating solution having a phosphorous content of 1% to 4% by weight, and wherein the electroless gold plating is carried out by dipping the substrate in a non-cyanide electroless gold plating solution comprising, as a complexing agent of gold, a compound represented by the formula shown below or a salt thereof: X—(CH 2 ) n —SH wherein n is 2 or 3 and X is SO 3 H or NH 2 , and having a pH value of 7 or less.