Ultrasonic bonding with variable amplitude fuzzy control based on force signals for Polymethyl Methacrylate

Abstract

Ultrasonic bonding is an emerging technology in the field of micro-assembly. Traditional ultrasonic bonding processes are controlled by time, pressure, or electrical energy, but higher precision is required for interface fusion control. In this paper, a variable amplitude ultrasonic bonding method based on fuzzy control is proposed. Two fuzzy controllers are designed by the fuzzy control algorithm with dynamic and static force signals as inputs and ultrasonic amplitude as output. In the early stage of bonding, the initial melting of the contact surface is accelerated, and the generation of overflow defects is inhibited by the realization of a large amplitude. In the middle and late stages of bonding, the whole interface fusion is achieved with smaller amplitudes to weaken the bubble defect. The bonding experiment between the micro connecting tube and substrate of polymethyl methacrylate (PMMA) is carried out to investigate the fusion of interface. The effects of different amplitude parameters on air bubbles and overflow defects are analyzed. Results indicate that the suppression of overflow and air bubbles is obvious, and the overflow ratio can be reduced to 2%. The stability and accuracy of interface fusion are improved.