Microstructure and Shear properties of Sn-xZn Transient Liquid Phase Bonding in 3D-Chip Stacking Packaging

The microstructure and shear property of Cu/Sn-xZn/Cu (x = 0, 2, 5, 9, 30, 70 wt.%) composite solder joints fabricated by transient liquid phase (TLP) bonding were investigated. The results showed that the appropriate amount of Zn particles inhibited Cu-6(Sn, Zn)(5) phase formation at the Cu/solder interface. The Zn particles can improve the interface IMC morphology of composite solder joints, the interface IMC thickness of Cu/Sn-30Zn/Cu solder joint is only 3.89 mu m, and the excessive (30-70 wt.%) Zn particles are harmful to the composite solder joints. Doping 2-9 wt.% Zn particles can improve the shear strength. The maximum shear strength value of the Cu/Sn-9Zn/Cu composite solder joint reaches 14.18 MPa. The fracture mechanism is mainly ductile brittle mixed fracture, which occurs near the Interface reaction zone.