The Preparing And Property Research Of High Thermal Conductivity Micro/Nano Epoxy Composites

With the rapid development of science and technology,semiconductor-based electronic devices are able to be smaller,lighter,cheaper and higher integration to meet needs of industrial production and social life.However,the development of high-power electronic devices also leads to the increase of work intensity and work temperature.Over high operating temperature will damage the performance and reliability of the electronic devices,and improve the probability of its failure.Thus,effective thermal management of electronic devices is essential to ensure its high performance.Electronic packaging material we focus on mainly provide circuit support and protection,heat dissipation and insulation for integrated circuit.Epoxy resin is the preferred material used in plastic electronic packaging because of its excellent adhesion,great chemical resistance,mechanical property,electrical insulation and low thermal expansion.The thermal conductivity of epoxy(0.2W/m·K)is too low so that high thermal conductivity fillers have to be embedded to improve the ability of heat dissipation.However,the addition of a large amount of inorganic filler will destroy the flowability of epoxy and it is difficult to meet the requirement of packaging process.Therefore,it is necessary to develop a kind of epoxy composite which possesses high thermal conductivity,low viscosity,great mechanical property and good electrical insulation performance simultaneously.In this research,a micro/nano filler system with an average particle size of 5?m spherical alumina(S-Al₂O₃)as main filler and a small amount of silver nanowire(AgNWs)as secondary filler is proposed to overcome the contradiction between thermal conductivity and processability of epoxy composites.Polyol synthesis is applied to prepare AgNWs.Epoxy/S-Al₂O₃ micro composites and epoxy/AgNWs/S-Al₂O₃ micro/nano composites are prepared by solution mixing method.Among them,AgNWs are well dispersed in composites and can effectively connect S-Al₂O₃ separated by epoxy to form continuous micro/nano thermal conductive filler network.Epoxy/AgNWs/S-Al₂O₃ composites have higher thermal conductivity than epoxy/S-Al₂O₃ composites,the highest thermal conductivity reaches to1.602W/m·K.Meanwhile,after the introduction of AgNWs,the viscosity of epoxy/AgNWs/S-Al₂O₃ composites are greater than epoxy/S-Al₂O₃ composites,but there is no synergetic increase in viscosity.Although the presence of AgNWs will decrease the electrical resistivity,the lowest electrical resistivity of composites is 1.3×10¹²?·cm,which still has great electrical insulation property.Besides,the appropriate proportion of multiscale fillers for synergistic filling has advantages in improving the heat resistance,storage stability,dimensional thermal stability and mechanical properties of epoxy resin composites.These results demonstrate the multiscale epoxy composites may solves the tradeoff between thermal conductivity and processability performances,and endows a good combination of high thermal conductivity,low viscosity and low CTE,along with good electric insulation performance of obtained low-cost epoxy packaging materials.