Method for forming gold bump connection using tin-bismuth solder

摘要

A gold bump contact on an electronic component is solder bonded to a bond pad of a printed circuit board or the like utilizing a solder composed of tin-bismuth alloy. The solder is applied to the bond pad as an electroplate or a paste, after which the gold bump is superposed onto the bond pad. The assembly is heated to a first temperature to melt the solder and thereafter maintained at a temperature less than 150 C. to permit the molten solder to wet the gold surface, after which the assembly is cooled to solidify the solder and complete the connection. Wetting at the relatively low temperature retards dissolution of the gold and thereby reduces formation of unwanted gold tin intermetallic compounds that tend to decrease mechanical properties of the connection.