Authored By:
Kyung-Wook Paik, Seung-Ho Kim, Kiwon Lee
Nano Packaging and Interconnect Lab.
Department of Materials Science and Engineering
Korea Advanced Institute of Science and Technology, Daejeon, Korea
Summary
A novel anisotropic conductive film (ACF) bonding process using ultrasonic vibration was investigated in touch screen panel(TSP)-on-board (TOB) applications. The ACF temperature increased as the U/S power increased and the bonding pressure decreased. The ACF temperature was successfully controlled by adjusting both U/S power and bonding pressure. The significant meaning of this result is that the ACF bonding process can be remarkably improved by U/S bonding compared with conventional T/C bonding. Using the optimized U/S bonding parameters, the ACF interconnects showed significantly less thermal damages to PET substrates and similar bonding performances as T/C bonding in terms of the contact resistance and the adhesion strength. And the cure degree of adhesive resin was achieved 90% at 3 sec.
In terms of thermal deformation, U/S bonding showed no severe thermal deformation of TSPs up to 120°C which is much higher than Tg of PET substrates. This result indicates that ACA can be heated up to 120°C without severe thermal deformation of the PET substrates by VUS. It is presumably due to the rapid heating rate and the short bonding time of VUS bonding. As a summary, the VUS method can be successfully used in touch screen assembly with high speed and good reliability.
Initially Published in the SMTA Proceedings
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