Transient liquid phase bonding of Sn-Bi solder with added Cu particles

The aim of this study was to apply the transient liquid phase (TLP) bonding technique to low-temperature Sn-Bi-based solders to enable their use in high-temperature applications. The microstructure of the eutectic Sn-Bi solders with and without added Cu particles was investigated with the solders sandwiched between two Cu substrates. The flux of the Cu atoms successfully consumed the Sn phase and resulted in the formation of Sn-Cu intermetallic compounds and a Bi-rich phase in the solder joint. This caused the melting point of the solder joint to increase from 139 to 201 A degrees C. The results of this study show the potential of using low-temperature solders in high-temperature applications. This study also provides new insight into the advantages of using particles in the TLP bonding process.