Preparation And Properties Of Boron Nitride/Epoxy Resin Thermal Conductive Composites

With the rapid development of electronic technology,electronic products are also rapidly developing and popularizing.The density of electronic assembly is increasing,the volume is also shrinking,electronic products are becoming more and more miniaturized,and more components are concentrated in a small space at high frequencies.Under work,a large amount of heat will be generated quickly,and overheating of electronic equipment will reduce the reliability of the equipment,resulting in collapse or even permanent damage.The heat generated by the device needs to be exported in time through the packaging material,otherwise it will affect the performance of the device.Therefore,the packaging material should have good thermal conductivity.How to quickly derive the heat generated by the electronic device has become a research hotspot.In order to meet the requirements of rapid heat dissipation,Electronic packaging materials should have high thermal conductivity to ensure the normal operation of electronic products.Heat dissipation technology is crucial for the development of a new generation of lighter and smaller electronic products.Thermally conductive materials have become a research hotspot.At present,low-cost and excellent polymer-based thermal conductive composite materials have received extensive attention,especially nitrogen.Boron nitride（BN）is a polymer-based composite material that is a thermally conductive filler.This is due to the high thermal conductivity of BN and the high thermal stability in air,which makes BN a potential application in the field of heat conduction.In this thesis,the surface modification of boron nitride is carried out in the epoxy resin to improve the thermal conductivity of the composite.In this paper,a series of epoxy resin matrix composites with good thermal conductivity and excellent comprehensive properties were prepared.The effects of particle size and content of BN on the properties of composites were systematically studied.The effect of BN surface modified fillers with different modifiers on the properties of composites was studied.The effect of mixed fillers BN-Ag and BN-Si₃N₄ on the properties of composites was also investigated.In this paper,the effects of particle size and content of micron-sized BN and nano-sized BN on the properties of composites were investigated.Studies have shown that the larger the particle size of micron-sized BN（8-14μm）and the micron composite when the BN content is 20%.The thermal conductivity of the material is the highest,the specific surface area of??the nano-sized BN is larger,and the thermal conductivity of the nanocomposite is the highest when the BN content is 20%.When the BN content is 20%,the thermal conductivity,thermal stability and heat resistance of the nanocomposites are better than those of the microcomposites.BN was surface treated with different concentrations of coupling agents KH-550 and KH-570.The effects of the addition of KH-550-BN and KH-570-BN on BN/epoxy resin（EP）composites after different amounts of coupling agents were modified.BN,KH-550-BN,KH-570-BN and their composites were characterized by FTIR,XRD,SEM,TG,etc.The results showed that the coupling agent successfully modified BN,and it was known by SEM that after KH-550 and KH-570 modification,the BN agglomeration is reduced,and the dispersion in the EP matrix is??relatively uniform.Therefore,the addition of the coupling agent can improve the thermal conductivity of the composite,and as the content of the coupling agent increases,the composite material The thermal conductivity increases first and then decreases,and when the content of KH-550 and KH-570 is 1%,the thermal conductivity of KH-550-BN/EP and KH-570-BN composites is best and improved.The effect is better than BN/EP;the addition of coupling agent will slightly improve the thermal stability of the composite,and has little effect on the notched impact strength of the composite.In this paper,epicatechin（EC）was used as a non-covalent modifier to surface treatment of boron nitride（BN）.After different levels of EC modified BN,the impact of the addition of BN@EC on BN@EC/epoxy（EP）composites.The BN,BN@EC and BN@EC/EP composites were characterized by FTIR,XRD,SEM,TG,etc.The results showed that the dispersibility of BN modified by epicatechin in the resin matrix was improved,BN The thermal stability of@EC/EP composites is improved.When the catechin content is 10%,the BN@EC/EP composite has the best thermal conductivity,the thermal conductivity of the material reaches 1.2727W·m^-1·K^-1,compared with the thermal conductivity of BN/EP of 0.6188W·m^-1·K^-1,it is increased by 106%.In this paper,Ag and BN are used as composite thermal conductive fillers,which have the effect of synergistic heat conduction.When the addition amount of Ag is 5%and the amount of BN added is 15%,the thermal conductivity of composite BN-Ag/EP can reach 1.067W.·m^-1·K^-1,which is 67.66%higher than the thermal conductivity of BN/EP of 0.63647 W·m^-1·K^-1.At the same time,the excellent mechanical properties and thermal properties of EP are basically maintained.Si3N4 and BN are also used as compound thermal conductive fillers,which have synergistic effect of heat conduction.When Si₃N₄ is added in 10%and BN is added in 10%,the thermal conductivity of composite BN-Si₃N₄/EP can reach 1.148W.·m^-1·K^-1,which is 85.16%higher than the thermal conductivity of BN/EP of 0.6200 W·m^-1·K^-1,while maintaining the excellent mechanical and thermal properties of EP.