关键词: 疲劳寿命, 蠕变, 塑性变形, 温度场, 有限元

Abstract: Based on Garofalo-Arrheninus model, the temperature field, stress-strain field and deformation of soldered joints are simulated by using finite element software Marc. The fatigue life of soldered joints is calculated by means of modified C-M equation. The results show that among the device materials, only the interior of printed circuit board has uneven distribution of temperature field because the thermal conductivity coefficient of material is too small. The heel and the toe of soldered joints, and the junction between soldered joint and lead are stress concentration zones. The result of simulation based on Marc software agrees with that based on Ansys software, and they are in good agreement with the actual situation. Time history creep and plastic strain emerge the obvious trend of accumulated enhancement. The combined action of both leads to the destruction of soldered joints and the failure of device. During the process of temperature cycling loading, the whole device is always in a tensile stress state. The fatigue life of soldered joints calculated on the basis of modified C-M equation is 665.7 cycles, which is basically in agreement with the experimental result.

Key words: Creep, Fatigue life, Finite element, Plastic deformation, Temperature field