Using lateral vibration for thermosonic flip-chip interconnection with anisotropic conductive film

Abstract

In this paper, thermosonic flip-chip bonding with anisotropic conductive film (ACF) is considered. To shorten the ACF curing time, an ultrasonic vibration of 40 kHz in the lateral direction is applied, in addition to the thermocompression process. By measuring the internal temperature of CF, the fast curing of ACF due to ultrasonic vibration is verified. The experiments with a commercialized ACF for the interconnection of LCD driver chips exhibit a notable reduction of bonding time by 77% as well as a reduction of tool-tip temperature while ensuring the bonding reliability. Also, as a typical feature of the proposed method, the sliding phenomenon between the contact surface of the specimen and the horn tool-tip is reported, which significantly enhances the reliability of thermosonic flip-chip bonding. Through the observation of pressured conductive particle