Comprehensive modeling and analysis of copper wire bonding process

In this paper, the copper property under various ultrasonic powers was firstly investigated by experiment. It is found the ultrasound has an acoustic softening effect on copper free air balls (FABs). The stress-strain behavior of copper FABs that accounted for acoustic softening effect was achieved by combining experiment and numerical simulation. Then a non-linear finite element (FE) model was built to study the copper wire bonding process. The model considered the sliding status transition at the bonding stage and can give an accurate prediction on the catering issue. Finally, one case study about the BAR effect on the bonding stress was conducted. The bonding stress can be reduced by optimizing the BAR value of the bonded ball.