Layer Structure and Thickness Effects on Electroplated AuSn Solder Bump Composition

The eutectic gold-tin (AuSn) solder composition is receiving increased attention for packaging applications. In addition to the environmental benefits of removing lead compounds from electronic manufacturing, gold-tin eutectic also exhibits desirable mechanical properties such as high strength and low thermal fatigue. However, some methods of deposition for this solder require complicated processes or limit the minimum bump size. This paper explores the formation of AuSn eutectic solder bumps using sequential electrodeposition of Au and Sn to determine the effect of layer thickness and sequence on the composition and structure of the resulting solder bump