Wire bonding method

Abstract

The objective of this invention is to provide a method for bonding wires using a core material primarily composed of Ag and a coating layer primarily composed of Au, which can form a well-shaped FAB with high sphericity in the atmosphere. The bonding method of this invention includes a solder ball forming step, in which a discharge occurs between the leading end of a bonding wire W, on an Ag-based core material 5 and a discharge electrode, forming a solder ball at the leading end of the bonding wire. The solder ball forming step includes: a melting step, in which a first discharge occurs between the leading end of the bonding wire W and a discharge electrode 51, melting the leading end of the bonding wire W with the discharge current of the first discharge to generate a molten wire; and a slow cooling step, in which a second discharge occurs with a discharge current value smaller than that of the first discharge, until the molten wire generated in the melting step solidifies again.

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