This paper presents the manufacture and testing of nano/micro epoxy resins and their properties. In order to prepare the specimens, a main resin, a hardener, an accelerator and a nano/micro filler were used. Varying amounts of CuO and Ag nano fillers were added to the epoxy mixture along with a fixed amount of micro silica. The thermomechanical and electrical properties of these mixtures were then determined by DC breakdown (DCBD) test and TMA analysis. The DCBD strength value of the composites can be described by a Weibull distribution. Totally, the epoxy resin exclusively filled with the nano particles had better electrical properties than micro composite in which there isn't nano filler. However, according to the quantities and type of filler, the properties of the epoxy composites were not found to be linear or proportional. There were optimal combinations and ratios. This results can be explained by Nordheim's rule. And it was confirmed that thermal expansion coefficients (TEC) of nano-epoxy composites have similar value with Al or Cu.

Keywords: Epoxy resin, Nano filler, Thermal expansion coefficient, Dielectric breakdown