Sepiolite Fiber Supports Tin Powder and Boron Nitride to Prepare Epoxy Composites with Insulation Properties and High Through-Plane Thermal Conductivity

Metal fillers are not suitable for direct mixing and casting with thermosetting resins to prepare thermally conductive and insulating materials due to their high density and electrical conductivity. Here, we obtain a filter cake by mixing sepiolite fiber, tin powder, and h-BN through vacuum filtration. Low melting point tin particles are melted and allowed to infiltrate to fill the void defects around them after the filter cake is heat-treated, and the added h-BN will coat the tin particles to prevent them from coming into contact with each other to conduct electricity but does not hinder heat conduction. The test results show that when the tin powder content is about 47.2 wt %, the thermal conductivity can reach 3.37 W/m·K and the volume resistance is still greater than 109 Ω·m. This method provides an idea for the preparation of high thermal conductivity metal-thermosetting resin composite materials.