Construct Insulation And High Thermal Conductivity Epoxy Resin Composites Based On Multi-scale BN Network

With the rapid development of semiconductor technology,the power density of electronic components is increasing rapidly,leading to the increasingly serious problem of heat accumulation.Researches show that the performance of electronic devices decreases by 50%for every 10?increase in temperature.Therefore,efficient thermal management has become the key to guarantee the working life and reliability of high performance electronic devices.In recent years,high thermal conductivity filler reinforced polymer composites have been widely studied and used in the field of thermal management due to their advantages such as light weight,excellent machining performance and corrosion resistance.In the traditional blending process,the interfacial thermal resistance between thermal conductive filler and polymer matrix limited the improvement of thermal conductivity of composites.In recent years,researchers have achieved a significant reduction in interfacial thermal resistance and a significant improvement in thermal conductivity of composite materials through prefabricated thermal conductivity network combined with polymer filling and curing process.However,the high viscosity and low fluidity of the polymer matrix make it difficult to completely fill the network pores.Due to the low density of the prefabricated thermal conductivity network results in the low thermal conductivity of the composite.How to construct high density thermal conductivity network in polymer matrix becomes the key problem of improving thermal conductivity of composite materials.Herein,inspired by the multi-scale network structure of plant veins,a two-stage boron nitride continuous thermal conductivity network with adjustable structure was constructed in epoxy resin(EP)matrix to construct high density thermal conduction network and enhance the thermal conductivity of polymer composite.The main heat conduction network MS@BNNS was constructed by coating MS with boron nitride nanosheets(BNNSs).The secondary heat conduction network BN/EP can be formed by adding the dispersed BN into the epoxy matrix.Multiscale structure boron nitride reinforced epoxy resin composites are obtained by impregnating BN/EP into the MS@BNNS followed by the deformation and crosslinking.Based on the hyperelasticity of network,the microstructure(orientation and density)and thermal conductivity of BN network are controlled by compression deformation.The formation of the secondary thermal conduction channel in EP substrate was controlled based on the filling amount of BN.The interface structure and thermal conductivity between BN and EP were regulated based on dopamine modification.At 95%compression the in-plane and cross-plane thermal conductivity of the composite reached 10.2 and 4.95 Wm^-1K^-1 respectively at BN loading of 35.9 wt%,and the highest value is 52 times of pure epoxy resin.Combined with the finite element analysis,the high thermal conductivity is mainly due to the formation of high density phonon transmission pathway provided by the two-level BN network.Owing to the outstanding thermal conduction and electrical insulation performance,this composite has a great prospect as integrated circuit board for thermal management in electronic device in the future.