Abstract: For SnAgCu/SnAgCuCe solder joints, the microstructures, mechanical property and thermal fatigue property are investigated respectively. Results indicate that the mechanical properties of SnAgCu solder joints are enhanced with the addition of Ce, and the tensile forces of SnAgCuCe solder joints are 12.7% higher than that of SnAgCu solder joints. With the addition of rare earth Ce, the microstructure of SnAgCu can be refined, and the size of intermetallic compound (IMC) particles (Cu6Sn5 and Ag3Sn) can be reduced, which are the reasons for the mechanical properties enhancement of SnAgCu solder joints. The SEM inspection and analysis show that fracture of the SnAgCu/SnAgCuCe solder joints presents obviously toughness fracture mechanism. In addition, during thermal cyclic loading, it is found that the addition of rare earth Ce can enhance the fatigue life of SnAgCu solder joints. Based on finite element simulation, it is found that SnAgCuCe solder joints shows higher creep resistance than that SnAgCu solder joints.

Key words: Lead-free solder joints, Mechanical property, Rare earths, Toughness fracture