Evolution of Interfacial Shear Force during Ultrasonic Al Ribbon Bonding

Abstract

An Al ribbon was bonded to SiO₂ substrate with a 60 kHz ultrasonic wedge bonder. The shear force applied at the interface between the ribbon and the substrate was measured with a piezoelectric load-cell. Simultaneously, the vibration amplitude at the tip of bonding tool was monitored with a laser-Doppler vibrometer. It was suggested from experimental results that the maximum interfacial shear force was 6.4 times larger than the bonding force, i.e., the friction coefficient at the interface could be significantly high during ultrasonic bonding. The evolution and the transmission of the interfacial shear force were discussed, based on numerical simulations. The purpose of the present study is to reveal the evolution of interfacial shear force at the interface during ultrasonic ribbon bonding.