Transient liquid phase bonding method of SnIn for high-temperature packaging

With the increasing development of semiconductors materials and technology, higher demands are emphasized on the packaging methods and materials for the high-temperature electronics. In this investigation, a novel packaging method by eutectic SnIn solder foils using transient liquid phase (TLP) bonding without pressure was introduced, and the microstructures as well as performance evolution of joint bonded at different bonding parameters were analyzed. During the bonding process, the solder alloy as well as weak Cu₂In were gradually consumed, and full Cu₆(In, Sn)₅ bondline could be obtained without any obvious defects at only 200 °C. Higher temperature and longer time could give a further enhancement on the microstructure and the mechanical performance, where dense robust Cu₃(In, Sn) bondline formed. Owing to the microstructure optimization, the average shear strength of bonded joint increased by 301.87%. With the great performance and eco-efficiency, this novel TLP-bonding method using SnIn solder foil is capable to meet the increasing requirement of high-temperature packaging.