The Si₃N_4w/Epoxy are the composites with Si₃N_4w as reinforcement and epoxy resin as matrix, which have high strength, toughness, thermal conductivity and dielectric strength as well as low dielectric loss and thermal expansion coefficient. The specific performance of Si₃N_4w/Epoxy is shown in Table 3.1. It is mainly used for insulating packaging resin in the electronics industry and high-performance composite structural parts in the aviation field.