Parameter Sensitivity Analysis for Thermosonic Bonding Process by Finite Element Method

In present study, the bond strength is discussed as the target functions of sensitivity analysis by FE methods. The complete ball bonding process including both the impact and ultrasonic vibration stages is modeled, and the strain rate sensitivity of the gold ball and pad is considered. The bond strength is studied by analyzing the interfacial deformation behavior, and the variable s, sum of segment extensions in bond interface, is defined to establish the relationship between bonding interfacial deformation and bond strength. The effects of FAB size, constant velocity, bonding force, and USG level on bonded ball size and bond strength are investigated respectively, and the simulation results, which are consistent with experimental one, are acquired. Furthermore, the sensitivity analysis of muti-parameters is also studied by the orthogonal experiment design.