(A) study on the interface of organic rigid substrates and flexible substrates bonding using anisotropic conductive adhesives

Abstract

In this study, the interface of a organic rigid subsrate and a flexible substrate bonding by using anisotropic conductive flims (ACFs) were investigated. In fact, ACFs have been widely used in electronic packaging area, especially, flip chip bonding on an orgarnic substrate, a glass substrate, or a flexible substrate. Hence, chip interconnection using ACFs has been technologically matured. In recent, the portable electronic products have pursued multi-functionality in a body and this multi-functionality is achieved by a modular approach. The key of the modular approach is how to connect functional modules to a main rigid board and the rigid substrate and the flexible substrate bonding technology using ACFs is a promising modulation mehod. Chapter 3 is about the formation of process-related bubbles inside the adhesive layer during RS-FS bonding. These bubbles can reduce the mechanical property, such as the adhesion strength of ACF joints, and induce moisture penetration and moisture entrapment at flexible substrate and ACF interface during reliability tests in humid environments. Consequently, bubbles also can deteoriorate the reliability of ACF interconnection joints. However, the reasons for the formation of bubbles during ACF bonding processes and the effect of these bubbles on ACF joints reliability have not been fully understood. Actually, there are several possible causes for bubble formation, such as bonding process variables and flexible substrate types. Accordingly, the process-related bubble formation was studied in terms of bonding process variables and flexible substrate types. According to the results, the bubble formation was significantly affected by bonding temperature. That is, fast curing at high temperature can make resin flow difficult so that bubbles form more easily at higher bonding temperature. In chapter 4, the effect of the type of flexible substrates on the adhesion between PI surfaces and ACFs and was investigated. The s...