Granular modeling approach to electro-packaging materials

The particulate material to be used for electro-packaging of LSI-chip is a compound of polymer matrix and silica particles. In its materials design, a volume fraction of silica must be designed to reduce the difference of thermal expansion coefficients between the compound and the semiconductive device. Since the loading ratio of silica particles in the polymer matrix reaches to 60 vol.% in actual situation, the viscous flow of the compound can be identified as a non-Newtonian fluid; since nonlinear viscosity changes itself even in local with the process time, various defects or porosities have to be left in the final product. In other words, new materials processing design is necessary to rationally determine the geometry and dimensions of a die-set system and to adequately optimize the process parameters. In the present paper, a granular modeling is proposed to describe the rheological behavior of this high-loaded particulate compound. Use of this modeling enables us to make direct process simulations for investigation of the formation of defects and understanding of mechanism to be free from defects. Simulated results indicate a rational possibility for the present granular modeling to be used for the related materials processing design to the particulate electro-packaging materials.