High thermal conductive epoxy resins with controlled high order structure

Present electrical devices have large calorific power, and improvement of heat dissipation has been a very important subject. In this paper, we developed the novel epoxy resins which increased the thermal conductivity that has been a barrier to heat dissipation. The medium of thermal conduction for insulating resins is phonons. Phonon conduction depends on the crystallinity, since it is a lattice vibration. The scattering of phonons happens on the interface of an amorphous structure. If there is a macroscopic amorphous structure although crystal structure exists on the microscopic level, we expected that high thermal conduction could be attained by reduced scattering of phonons through controlling the nano scale structure. Using an epoxy resin which has the mesogen structure would solve this problem because it's easy to carry out an orientation with this structure. As a result, we confirmed that thermal conductivities become larger when the amounts of mesogens were increased. The epoxy resin (A) contains biphenyl mesogen, and the epoxy resin (B) contains even bigger mesogenic units. The epoxy resin (A) was about two times higher than the conventional epoxy resin, and the epoxy resin (B) was able to attain five times as much thermal conductivity as the conventional one.

INTRODUCTION

Both electric and electronic apparatuses have recently improved in size and performance with increasing heat quantity from the conductor inside and have large and important subjects to diffuse the heat efficiently in their design. Although the thermoset resins are mainly used for insulating materials with thermal resistance, they have quite low thermal conductivities, usually a 1–3 order lower than those of ceramics and metals, to greatly prevent the heat from diffusing. A technical key point of the apparatus should be to use insulating materials having higher thermal conductivities. One approach is generally known and is used to apply composites of thermosets with inorganic ceramic powders having high thermal conductivities. This is effective for heat diffusion to some degree, but usually affects working, molding and processing and have high elastic moduli and low flexibilities. It became clear recently that ceramic powder might affect the curing reaction of the resin, too [1]. These would give us additional subjects.