Leiterplatte mit lötbarer dünner Metallschicht zum Auflöten von elektronischen Bauelementen

摘要

A solder bonding metal layer which is formed on a circuit board comprises a metal layer having a mixture of first metal which is easily wetted with metals constituting the solder and which easily forms alloy or intermetallic compounds and of second metal which is not wetted easily with the above solder and not melted. In this case, a concentration gradient that the concentration of the first metal is high on the bonding surface may be formed in the metal layer. A circuit board having a solder bonding metal layer which keeps good bonding even after many times of repairs and improves the reliability is realized.