Abstract
Epoxy resins with controlled high-order structure have higher thermal conductivities than conventional ones, because the crystal-like domains, self-arranged ‘mesogen’ groups of the epoxy monomers, promote smooth phonon transportation. Although thermal conductivities of these epoxy resins are 1.0 W/m·K at a maximum, these are not enough to apply to electric devices which require high heat dissipation efficiency. In this paper, we composed these resins and alumina fillers, to accomplish the epoxy resin composites which have both isotropic high thermal conductivities and electrical insulation. Though these epoxy monomers are difficult to handle because of their crystallinity and poor solubility in solvents, we conclude that the conventional forming process for thermosetting resins such as transfer molding are applicable to these composites by optimizing the molecular architectures of hardeners. Both high thermal conductivity as 5 W/m·K and excellent flow property were accomplished for molding compounds using developed composites. And developed molding compounds were applied to the plastic ball grid array (P-BGA) semiconductor packages and the bobbins for concentrated winding motors, then good heat dissipation properties were shown for both applications. We conclude that developed molding compounds are effective for thermal management of electric and electronic devices.
