Patent ID: 7417316

Claim:
A wired circuit forming board comprising: an insulating layer, and a thin metal layer formed on the insulating layer; wherein the thin metal layer comprises a first metal and a second metal of different kinds and is formed to prevent formation of an interface between the first metal and the second metal in a thickness direction of the thin metal layer by a presence of a metal coexisting portion where the first metal and the second metal are coexistent with each other; wherein the metal coexisting portion exists in a thickness direction of the thin metal layer in a proportion of 50% or more; and wherein the thin metal layer has a high existence ratio of the first metal and the second metal on one thickness-wise side thereof adjacent to the insulating layer and a high existence ration of the second metal to the first metal on the other thickness-wise side thereof not adjacent to the insulating layer, and wherein the metal coexisting portion exists at least partway along the thickness direction of the thin metal layer.