Electrical and mechanical properties of anisotropic conductive polymer adhesives for electronic packaging interconnection materials

Abstract

The electrical and mechanical properties of Anisotropic Conductive Adhesives/Films (ACAs/Fs) for electronic packaging interconnection materials were investigated in this study. Thermo-mechanical properties of newly modified ACA/F were mainly discussed in order to achieve the improvement of thermo cycle reliability of flip chip on organic substrate using ACA/F. For electrical properties, high frequency characterization of flip chip interconnection using ACF were mainly performed, and high frequency properties were improved by using low dielectric ACA/F materials. In chapter 1 and 2, introduction and literature survey for this study were described respectively. In chapter 3, the conduction mechanism of interconnection constructed by ACF was investigated. Analytical models with the consideration of elastic deformation of contact material were used to evaluate the several factors of electrical contact, and FEM to investigate the electrical conduction through the large deformation of conductive particles or conductor substrate. Experimental verification was also performed. Electrical conduction through the pressure engaged contact area between conductive particles and substrate is the main conduction mechanism in ACF interconnection. Therefore, the bonding pressure plays an important role in the electrical properties of ACF interconnect with pressure dependent conduction mechanism. In general, as bonding pressure increases, a sharp decrease of contact resistance followed by a constant value are observed after reaching the critical bonding pressure. Contact resistance of ACF is determined by the contact area change between particles and contact substrate. Therefore the number, the size, and the hardness of electrical conductive particles are important variables. When more conductive particles are added, the connection resistance rapidly decreased and then became constant. This is because the counter-effect of two opposing factors, the resistance increase by a decrea...