A Study on the Anchoring Polymer Layer (APL) Anisotropic Conductive Films (ACFs) with Self-Exposed Conductive Particles Surface for Ultra-Fine Pitch Chip-on-Glass (COG) Applications

In this study, APL ACFs combined with self-exposed conductive particles surface are newly introduced. The effects of APL ACFs properties on conductive particle movement and interconnection stability for ultra-fine pitch COG applications were reported earlier. It was found that the APL structure will not only suppress the conductive particles movement during ACFs bonding process, but also prevent electrical short circuit formation between neighboring bumps for ultra-fine pitch applications. Since the APL material has high tensile strength, the capture rate of APL ACFs is about 3 times higher than that of conventional ACFs. However, to achieve a stable electrical interconnection, the APL ACFs require additional process steps such as an oxygen plasma etching process to remove the APL polymer skins coated on the top and bottom surfaces of conductive particles. In this study, the polymer skin can be removed during the APL fabrication process using the self-activate monolayer (SAM) treatment on conductive particles. As a result, stable ACFs joint formation can be achieved without any additional oxygen plasma etching process for APL fabrication processes.