Preparation And Properties Of Thermal Interface Materials With High Conductivity

In order to solve the heat dissipation problem of electronic components and other heat sinks,the development of advanced thermal interface materials(TIMs)has become more and more important.The thermal grease has a high thermal conductivity and can well reduce the interface contact thermal resistance when coated.The combination of liquid metal and metal foam can prepare a composite thermal interface material with two-phase bicontinuous network,which has high thermal conductivity and good thermal stability.In this paper,a series of aluminum powder/zinc oxide/silicone oil-based thermal grease and a foam metal/liquid metal composite thermal interface material with bicontinuous network structure were prepared.The main contents include:1.A series of aluminum powder/zinc oxide/silicone oil-based thermal grease was prepared by using aluminum powder and zinc oxide as heat conductive filler and dimethyl silicone oil as matrix.The morphology,particle size and particle size distribution of the thermally conductive filler were characterized by scanning electron microscopy(SEM).The thermal conductivity of the composite materials was tested on a thermal conductivity test machine TC3000D and LW9389.By measuring the thermal conductivity and thermal resistance of the prepared thermal paste,the influence of the particle size of the aluminum powder,the particle size of the aluminum powder,the filling amount of the thermal conductive filler,the ratio of the aluminum powder and the zinc oxide,the milling time and the milling speed,and the amount of crystalline graphite on the thermal conducting property of the thermal paste was investigated.The results show that increasing the solid content,particle grading,ball milling the thermally conductive filler and adding microcrystalline graphite is beneficial to the thermal conductivity of the thermal paste.When the amount of thermal filler filled is50 vol.%,the ratio of aluminum powder with size of 5.0?m,1.0?m,0.5?m is 5:2:3,and the volume ratio of aluminum powder to zinc oxide is 5:1,the amount of microcrystalline graphite is 4 wt.%,the prepared thermal conductive paste shows superiors performance.The thermal conductivity is 2.73 W/(m·K),and the contact thermal resistance with the test surface is 0.078?·cm~2/W.2.The thermal interface composite materials with bicontinuous network structure were prepared by using liquid metal as thermal base,foam copper and foamed nickel as heat-conducting reinforcements.The pore size and pore size distribution of the foamed metal were characterized by optical microscopy.The thermal conductivity and interface thermal resistance of the composite materials were tested on a thermal conductivity and interface thermal resistance test machine LW9389.The effects of porosity,pore size and pressure on the thermal conductivity of the metal foam/liquid metal composites were investigated.The cyclic thermal stability of the composites was also investigated.The results show that the composite material prepared from the foam metal with low porosity has high thermal conductivity.The foamed copper composites with a porosity of 95%and a pore density of 90 ppi has a high thermal conductivity of29.538 W/(m·K)at a test temperature of 60?and a test pressure of 70 Psi.The foamed nickel composite with a porosity of 95%and a pore density of 90 ppi has a thermal conductivity up to 20.094 W/(m·K)at a test temperature of 60?and a test pressure of 30 Psi.The prepared bicontinuous network structure foam metal/liquid metal composite thermal interface material has good cyclic thermal stability.