We develop a transient liquid phase sinter (TLPS) bonding using Sn-coated Cu micro-sized particles. With this bonding process, a thermally stable joint comprising Cu3Sn phase and a dispersion of ductile Cu particles can be obtained. The particle paste, which contained Cu particles with a thin Sn coating and terpineol, was used to join Cu substrates. The setup was bonded at 300 °C for 30s under an applied pressure of 10 MPa using a thermo-compression bonding system under a formic acid gas atmosphere for reducing the oxide layer on the Sn coating and the Cu substrate. After bonding, the TLPS joint showed a thermally stable microstructure with a good shear strength, which was fully consisted of Cu3Sn intermetallic compounds matrix and embedded ductile Cu particles. The kinetics of the microstructure transformation and high temperature reliability of the TLPS joint were investigated. After 300 °C isothermal aging for 200h, the shear strength and microstructure of the TLPS joints showed almost unchanged. The results demonstrate that joint with high-melting-point obtained by the TLPS bonding using Sn-coated Cu particle paste has the potential to fulfill the requirement of high temperature electronic packaging.
Production of Al-4.5mass%Cu alloy by transient liquid phase sintering.
