LCD구동 IC의 실장을 위한 초음파 ACF접합 기술

Abstract

In the paper, we develop the ultrasonic bonding technique for LCD driver chips having small size and high pin-density. In general, the mounting technology for LCD driver ICs is a thermo-compression method utilizing the ACF (An-isotropic Conductive Film). The major drawback of the conventional approach is the long process time. It will be shown that the conventional ACF method based on thermo-compression can be remarkably enhanced by employing the ultrasonic bonding technique in terms of bonding time. The proposed approach is to apply the ultrasonic energy together with the thermo-compression methodology for the ACF bonding process. To this end, we design a bonding head that enables pre-heating, pressure and ultrasonic excitation. Through the bonding experiments mainly with LCD driver ICs, we present the procedures to select the best combination of process parameters with analysis. We investigate the effects of bonding pressure, bonding time, pre-heating temperature before bonding, and the power level of ultrasonic energy. The addition of ultrasonic excitation to the thermo-compression method reduces the pre-heating temperature and the bonding process time while keeping the quality bonding between the LCD pad and the driver IC. The proposed concept will be verified and demonstrated with experimental results.