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 di fference of thermal expansion coefficients between the compound and th e semiconductive device. Since the loading ratio of silica particles i n the polymer matrix reaches to 60 vol.% in actual situation, the visc ous flow of the compound can be identified as a non-Newtonian fluid; s ince nonlinear viscosity changes itself even in local with the process time, various defects or porosities have to be left in the final prod uct. In other words, new materials processing design is necessary to r ationally determine the geometry and dimensions of a die-set system an d 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 format ion of defects and understanding of mechanism to be free from defects. Simulated results indicate a rational possibility for the present gra nular modeling to be used for the related materials processing design to the particulate electro-packaging materials. (C) 1998 Elsevier Scie nce Ltd. All rights reserved.