Transient Liquid Phase Soldering-An emerging joining technique for power electronic devices

The Transient Liquid Phase Soldering (TLPS) is a new lead-free joining technology for power electronic modules in high temperature applications. This alternative solder interconnection technology is based on a phase transformation using a low melting solder powder, like eutectic Sn-based solder, and a high melting powder, e.g. Cu. The bonding temperature of such a TLPS interconnection is in the range of typical Sn-based solders, which is around 240 °C. The resulting interconnection is characterized by an almost void-less joint of Cu6Sn5 and Cu3Sn intermetallic phases. Due to this fact, the re-melting temperature of such a joint can be increased up to the decomposition temperature of the Cu6Sn5 intermetallic phase which is 415 °C. The basic requirements of the joining material and process will be discussed in this study.