The Influence Of Surface Modification Of Aluminum On Properties Of Aluminum/Organic Silicon Thermal Interface Materials

With the development of electronic products towards high integration,multifunction and miniaturization,the packaging density of electronic components or power devices also increases sharply.Therefore,the thermal management of electronic products has become one of the biggest problems in its development.To solve this problem by preparing high performance thermal interface materials has become a common understanding in industry and scientific research.In this thesis,after analyzing the current research status and problems of polymer-based thermal interface materials at home and abroad,the influence of filler surface energy and fine tuning of filler surface chemistry on the micro/macro properties of aluminum/silicone thermal interface materials is investigated by means of the tuning of filler surface chemistry to realize the interfacial construction and tuning of aluminum/silicone thermally conductive composites.The specific research results are as follows:(1)Although the surface energy of the filler has been considered as a key parameter,the dependence of the comprehensive performance of polymer-based thermal interface materials on the surface energy of the filler remains unclear.Here,we reveal the effect of the surface energy of aluminum on the thermal and mechanical properties of a thermal interface material consisting of polydimethylsiloxane and modified aluminum containing silane coupling agents of different chain lengths.The results show that reducing the surface energy of aluminum facilitates the dispersion of the aluminum filler in polydimethylsiloxane,thus improving the macroscopic properties,including rheology,mechanical properties and thermal properties.Among them,the viscosity can be reduced by 77%,the elongation at break can reach 154.71%,the thermal conductivity is also improved,the thermal homogeneity is significantly improved,and the thermal stability is increased by nearly 20% under extreme cold and heat cycling conditions.In addition,based on thermodynamic predictions,a winding mechanism is proposed to explain the interaction between modified aluminum and polydimethylsiloxane.This work reveals the mechanism of the influence of the surface energy of aluminum fillers on their dispersion and aluminum/silicone thermally conductive composites,which provides valuable guidance for the rational design of the surface energy of fillers in silicone thermal interface materials.(2)Using dodecyltrimethoxysilane(DTS)for the surface chemical treatment of aluminum filler,we achieve accurate control of the surface chemical properties of aluminum filler,by controlling amount of DTS addition and reaction time to adjust the amount of DTS on the surface of aluminum filler.The effect of the surface chemical properties of aluminum filler on its dispersion in organosilicon matrix and on the comprehensive properties of the prepared thermal interface materials was analyzed.The results show that the dispersion and interfacial state of aluminum filler in matrix are improved obviously with the amount of grafted DTS.Mechanical properties showed that the tensile strength and elongation at break increased by 212.5% and 150%,respectively,because of the strong interfacial interaction caused by the grafting of DTS.The toughness of TIMs increased with the increase of graft rate.Increasing the graft rate of DTS on filler surface could effectively enhance the toughness of TIM.In addition,the grafting of DTS improves the thermal performance of TIMs because it reduces the thermal resistance between filler and polymer matrix,and shows strong stability in high temperature storage and cold and hot shock experiments.This work provides experiment and data reference for the dispersion and interfacial interaction of fillers in organosilicon thermal interface materials,and establishes a method to optimize the properties of thermal interface materials by controlling the surface chemical states of fillers.