Research On Preparation And Thermal Conductivity/Heat Resistance Of Epoxy Resin Dielectric Composites

The third generation of wide band semiconductor chips represented by silicon carbide is gradually replacing silicon based chips,high performance packaging insulation materials is the key to give full play to the advantages of silicon carbide devices.The development of electronic packaging materials with high thermal conductivity,high temperature resistance and excellent insulation properties has become a hot research topic.Epoxy resins（EP）are widely used in electronic packaging due to their low cost and good electrical insulation.However,the low thermal conductivity and low glass transition temperature of epoxy resin itself cannot meet the demand of advanced packaging technology for efficient thermal management of packaging materials.In this thesis,we investigate the mechanism and methods for improving the thermal and electrical properties of epoxy resins based on multi-scale structural regulation,and systematically study the influence of multi-scale factors such as inorganic high thermal conductivity three-dimensional skeleton,filler size and molecular structure on the comprehensive performance of epoxy resins.In this thesis,boron nitride（BN）was selected as an inorganic thermally conductive filler to construct a three-dimensional porous BN skeleton based on aqueous-phase foaming and freeze-drying techniques.In combination with vacuum impregnation method,epoxy resin composites with continuous three-dimensional BN thermal conductivity network were obtained.The microstructure and properties of the composites were systematically investigated.The results showed that the out-of-plane thermal conductivity of the composites was 1.63 W/（m·K）at a BN content of 29.67wt%,which was 9.1 times higher than that of pure EP,with a low dielectric constant（4.34）and good insulation properties.To further optimise the three-dimensional thermal conductivity structure,the scale factor of the BN filler in the skeleton was tuned and its effect on the structure and properties of the epoxy composite system was investigated.The results show that at the same BN doping content,the thermal conductivity of the epoxy composites gradually increases with increasing BN filler sheet size,attributed to the fact that a large sheet size BN 3D skeleton significantly reduces the interfacial thermal resistance between the skeleton fillers.In addition,in order to improve the high temperature resistance characteristics of epoxy resin encapsulation materials and the high temperature service reliability of devices,the effect of introducing rigid organic molecular chain segment structures on the heat resistance of epoxy resins was investigated.Bisphenol A type cyanate（BADCy）was selected to co-polymerise with epoxy resin,and the introduction of a rigid triazine ring structure into the epoxy resin molecular chain would form a high crosslink density copolymer system.At a BADCy concentration of 50-60 mol%,the copolymer system reaches a maximum crosslink density of 12.8×10^-3 mol/cm³,exhibiting excellent glass transition temperature（>200°C）and thermal decomposition temperature(T_5%>400°C),while maintaining good electrical insulation properties.In this thesis,multi-scale structural modulation of epoxy resin-based composites is carried out to effectively improve their thermal conductivity,heat resistance and dielectric properties,providing an important reference for promoting the structural design and performance optimisation of high-performance electronic packaging materials.