Microstructure of Transient Liquid Phase Sintering Joint by Sn-Coated Cu Particles for High Temperature Packaging

摘要

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 Cu_3Sn 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 Cu_3Sn 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.