Exploring New Interconnection Materials and Techniques for High-Reliability IC Packaging

Accompanied by the increasing electrification and informationization in various devices and equipment, electric circuits (IC) are required to work in complicated and harsh environments. This significantly challenges the reliabilities of interconnections that bear electron current, heat, and mechanical loading. This research focuses on improving the reliability of interconnections serving at high-density current, wide temperature range, and high temperature, by exploring novel materials/techniques including i) βSn structure and orientation control technique, ii) SnGaX full solid-solution (SS) solder alloys, and iii) Sn-CuNi and Ga-Al transient liquid phase bonding (TLPB) technique. Controlling βSn structure and orientation is realized by harnessing the βSn heterogeneous nucleation using seed crystal, and this technique can be applied to Sn-based solder joints to combat reliability problems such as electromigration that is heavily influenced by the βSn orientation. The SnGaX SS solder is a novel patented material that takes advantage of Ga solid solution strengthening to achieve balanced strength and ductility. As opposed to the typical third-generation Pb-free solder Innolot that is too strong to bear plastic deformation, SnGaX SS solder demonstrates a good thermal cycling performance. Sn-CuNi and Ga-Al TLPB provide new solutions for power electronic assembling and they show good mechanical performance and low cost.