Preparation and evaluation of epoxy composite insulating materials toward high thermal conductivity

The aim of this study is to improve both thermal and electrical insulation properties of epoxy based composites using nanocomposite techniques. This paper deals with preparation of epoxy composites with high content of micro-filler and those several material characterizations. Types of filler and solvent, methods of mixing and casting were examined to achieve high filler content of more than 80 vol % in a commercial epoxy resin. Thermal conductivity, relative permittivity and dielectric strength were evaluated in each specimen. This study was mainly focused on alumina particles of spherical shape as primary micro-filler. In addition, effects of blending a different alumina, boron nitride, and silicon carbide particles into the alumina filler as secondary micro-filler were investigated on those several properties. As a result, micro-alumina 60 vol% filled epoxy composites of 0.2 mm thick was obtainable, and it was elucidated that its thermal conductivity is 4.3 W/m/K, its relative permittivity is 6.0, and its dielectric strength is 16 kV/mm. It is conclude that epoxy with hybrid fillers is useful for high thermal conductive composite materials for thin electrical insulating substrates.