摘要
The reliability of SMT soldered joints is one of the most important problems which need to be solved in the application of SMT. In this paper, the influence of grain size, stress and intermetallic compounds in joints is studied by means of testing the creep rupture life of joints at high temperature. It shows that all the crack surface consists of transgranular and intergranular fracture at 125℃, and grain size and stress are different because of different cooling rate.When the grain size is large and stress in joints is small, the creep rupture life is longer; otherwise, the life of joints decreases because of the viscid flow on grain boundary. When the Cu-Sn intermetallic compounds are present in the joints,the crack usually initiatesat the Cu-Sn compounds, the fracture tended to happen at the compounds area, and the creep rupture life will decrease with the thickness increase of Cu-Sn intermetallic compounds.
The reliability of SMT soldered joints is one of the most important problems which need to be solved in the application of SMT. In this paper, the influence of grain size, stress and intermetallic compounds in joints is studied by means of testing the creep rupture life of joints at high temperature. It shows that all the crack surface consists of transgranular and intergranular fracture at 125℃, and grain size and stress are different because of different cooling rate.When the grain size is large and stress in joints is small, the creep rupture life is longer; otherwise, the life of joints decreases because of the viscid flow on grain boundary. When the Cu-Sn intermetallic compounds are present in the joints,the crack usually initiatesat the Cu-Sn compounds, the fracture tended to happen at the compounds area, and the creep rupture life will decrease with the thickness increase of Cu-Sn intermetallic compounds.
