A study on the effects of anisotropic conductive film (ACF) properties on interconnection stability of ACF flip-chip assemblies

Abstract

In this study, the effects of anisotropic conductive film (ACF) properties on interconnection stability of ACF flip-chip assemblies were investigated. Recently, many researches related to the ACF interconnection stability and reliability have been carried out. In addition, many papers report that the ACF interconnection stability and reliability are closely related with ACF material properties. However, there are so many influencing factors on the ACF material properties and the fundamental understanding of these factors is not still sufficient. Therefore, the objectives of this research are to better understand the influencing factors on ACF properties and to investigate the effects of ACF properties on interconnection stability of ACF flip-chip assemblies. This thesis is divided into the following chapters. At first, chapter 2 is about the theoretical understanding and the quantitative analysis of the degree of cure of ACFs. The curing of ACF resin generates contraction stresses resulting in a good electrical and mechanical joint between the chip bumps and substrate electrodes. Therefore, the theoretical and quantitative analysis of the degree of cure of ACFs is important because ACF joints are stabilized through curing. In this chapter, the cure kinetics of an ACF was investigated by isothermal DSC analysis. The cure reaction of the ACF followed an autocatalytic cure mechanism, and the degree of cure of the ACF as a function of time and temperature was mathematically derived from an autocatalytic cure kinetics model. Thermal analysis was performed to investigate the thermal behavior of the ACF during the chip-on-flex (COF) bonding process by finite element simulation. The ACF temperature distribution during the COF bonding process was obtained by thermal analysis, and the degrees of cure of the ACF as a function of bonding times during the COF bonding process were theoretically predicted by the incorporation of the autocatalytic kinetics modeling and the...