Transient Liquid-Phase Sintering Bonding Based on Cu40Sn60 (wt.%) Core/Shell Particles for High-Temperature Power Device Packaging

In this study, a high-tin-content Cu@Sn core/shell (40 wt.% Cu-60 wt.% Sn) powder was fabricated for transient liquid-phase sintering bonding of high-temperature power device packaging. Benefitting from the high tin content Cu@Sn core/shell powder, a sound joint was obtained at 260°C, 300°C, and 340°C with a bonding pressure of 0.2 MPa. The effect of parameters on microstructure and shear strength of the bonding layer was researched. The results demonstrated that the bonding layer consisted of Cu6Sn5, Cu3Sn, and residual Cu particles when Sn was consumed. The differential scanning calorimetry curves showed that the resultant bonding layer could sustain high temperatures up to 400°C. The shear strength of the joint was enhanced with the increase of bonding time and bonding temperature, and the highest value was 43.2 MPa. Besides, compared to the joint achieved with mixed powders, a denser joint was achieved using the Cu@Sn core/shell powders.