The influence of thermal aging on reliability of Sn-58Bi interconnects

Abstract

The paper used Sn-58Bi interconnects to perform the thermal aging treatment under different times, namely one day, three days, fine days, seven days, fifteen days under 120°C. Then the tensile experiment was launched, the mechanical properties of solder joints were analyzed by looking at the joint defect, fracture and the IMC layer with SEM, combining with the tensile properties and fractograph analysis of the samples under different temperature, namely room temperature, 60°C, 80°C and 120°C, finally came to conclusions about reliability. According to the above experiments, some results can be found that as the aging time goes on, the IMC layer thickens, the strength of micro bumps has a tendency to continue to decrease, the fracture model is the brittle fracture and fracture position is given priority to internal fracture in solder, which may be associated with low tensile velocity. Under the condition of low strain rate, the decrease of the solder joint strength is mainly embodied in the damage of solder structure during the formation of chemical compounds. In addition, with the increase of temperature, the fracture model has been changed from the brittle fracture to the ductile fracture.