Si₃N₄ fiber-reinforced epoxy resin composites with different c-BN content for printed circuit board applications

Fiber-reinforced resin matrix composites are widely used in organic printed circuit boards (PCBs). However, conventional glass fiber reinforced epoxy resin (EP) matrix composites suffer from low thermal conductivity and poor electrical properties. Herein, to coordinate the thermal and electrical properties of the composites, a novel c-BN/EP/Si₃N₄ composite for PCBs was prepared by hot-pressing moulding method by selecting Si₃N₄ fibers instead of glass fibers and introducing nano cubic boron nitride (c-BN) particles as filler at the same time. Combined with Si₃N₄ fibers, nano c-BN filler with suitable content can further improve thermal transfer capacity and limit the volume shrinkage of EP during curing, resulting in the decreased porosity and strong interfacial bonding between Si₃N₄ fibers and EP. When c-BN content is 20 wt%, the c-BN/EP/Si₃N₄ composite shows excellent in-plane thermal conductivity (2.124 W m⁻¹ K⁻¹), low coefficient of thermal expansion (4.34 ppm K⁻¹) and excellent breakdown strength (55.71 kV mm⁻¹). Therefore, the c-BN/EP/Si₃N₄ composites have a potential application in the field of organic PCBs substrates.