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 ...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.展开更多
采用实验方法 ,确定了倒装焊 Sn Pb焊点的热循环寿命 .采用粘塑性和粘弹性材料模式描述了 Sn Pb焊料和底充胶的力学行为 ,用有限元方法模拟了 Sn Pb焊点在热循环条件下的应力应变过程 .基于计算的塑性应变范围和实验的热循环寿命 ,确定...采用实验方法 ,确定了倒装焊 Sn Pb焊点的热循环寿命 .采用粘塑性和粘弹性材料模式描述了 Sn Pb焊料和底充胶的力学行为 ,用有限元方法模拟了 Sn Pb焊点在热循环条件下的应力应变过程 .基于计算的塑性应变范围和实验的热循环寿命 ,确定了倒装焊 Sn Pb焊点热循环失效 Coffin- Manson经验方程的材料参数 .研究表明 ,有底充胶倒装焊 Sn Pb焊点的塑性应变范围比无底充胶时明显减小 ,热循环寿命可提高约 2 0倍 。展开更多
文摘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.
文摘采用实验方法 ,确定了倒装焊 Sn Pb焊点的热循环寿命 .采用粘塑性和粘弹性材料模式描述了 Sn Pb焊料和底充胶的力学行为 ,用有限元方法模拟了 Sn Pb焊点在热循环条件下的应力应变过程 .基于计算的塑性应变范围和实验的热循环寿命 ,确定了倒装焊 Sn Pb焊点热循环失效 Coffin- Manson经验方程的材料参数 .研究表明 ,有底充胶倒装焊 Sn Pb焊点的塑性应变范围比无底充胶时明显减小 ,热循环寿命可提高约 2 0倍 。
