In-Situ Observation of Adhesion Behavior During Ultrasonic Al Ribbon Bonding

Abstract

In-situ observation was performed on a transparent silica substrate during ultrasonic Al ribbon bonding, using a high-speed video camera with differing frame rates, 10 4 fps and 10 3 fps, to clarify the adhesion behavior. The bonding process was observed as follows. Initially, friction slip occurred, producing multiple island streaks in the direction parallel to the ultrasonic vibration. The island streaks were formed as a scratch, due to surface waviness of the Al ribbon. Momentarily, a belt-shaped bond zone was formed at the center, normally due to the ultrasonic vibration. The island streaks could be clearly observed at 10 4 fps. However, the central belt zone was unclear and appeared translucent at 10 4 fps; although it was clear when observed at 10 3 fps. The island streaks were unclear at 10 3 fps. The positional relation of the island streaks and the central belt zone was confirmed from in-situ observation results of a twist and peel test of Al ribbon bonded to silica substrate. The central belt zone was between the island streaks and the silica substrate.

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“…Ultrasonic bonding is widely used in industrial fields; however, there are still many unresolved phenomena. Takahashi et al directly observed the interfacial adhesion behavior during ultrasonic bonding between an Al ribbon and transparent silica substrate using a high-speed video camera with differing frame rates [27]. Initially, friction slip occurred, producing multiple island streaks in the direction parallel to the ultrasonic vibration.…”