Preparation Of Silica-based Thermal Paste With High Thermal Conductivity And Its Related Application

In recent years,miniaturization and integration have become the development trend of electronic equipment.As the power of electronic devices increases,the heat generated increases dramatically.Thermal interface materials can effectively improve the heat transfer between two solid interfaces,and play an important role in the performance,service life and stability of electronic devices.Because of its good fluidity,thermal conductivity grease can reduce the thermal resistance of the interface with the contact surface when coating,so it is widely used.In this paper,a series of alumina/aluminum nitride/silicone oil based thermal conductivity grease and alumina/liquid metal compound thermal conductivity grease with mutual coordination have been prepared.The main contents include:1.Using alumina and aluminum nitride as thermal conductivity filler and dimethyl silicone oil as matrix,pure alumina and alumina/aluminum nitride thermal conductivity grease were prepared.On this basis,the influence of ball milling process on the particle size of filler and thermal conductivity of thermal conductivity grease was explored.Scanning electron microscopy was used to characterize the morphology,particle size and particle size distribution of the thermal conductivity filler.The thermal conductivity of thermal paste was characterized by laser flash thermal conductivity tester.By measuring the thermal conductivity of thermal conductive paste preparation by the exploration of the alumina particle size and thermal conductive filler filling amount,ratio of alumina and aluminum nitride,ball grinding time and grinding speed impact on the thermal conductivity of thermal conductive paste.The results show that increasing the amount of filling and the combination of various fillers can improve the thermal conductivity of thermal paste.When the filling volume is 60 vol% and the volume ratio of alumina to aluminum nitride is 5:5,the thermal conductivity of the thermal paste prepared is better,and the thermal conductivity is 2.443 W/(m·K).Adjusting the parameters of ball milling can obtain alumina powder with better morphology and particle size,but the thermal conductivity of thermal paste decreases after ball milling.This may be because the ball milling makes the particle size of alumina smaller,the surface area of the filler larger,resulting in more interfacial thermal resistance,resulting in the decrease of thermal conductivity.2.Liquid metal and alumina are selected as thermal conductive fillers.Through the electron orbital coordination between alumina and liquid metal,liquid metal/alumina powder containing 20,40,60,80vol% is prepared first,and then mixed with dimethyl silicone oil to prepare composite thermal conductive silicone grease.The morphology of liquid metal/alumina composites was characterized by scanning electron microscopy.The peak of gallium oxide in composites was measured by Fourier infrared spectrometer.In situ electrochemistry was used to measure the variation of characteristic peaks of X-ray diffractometer composite.X-ray photoelectron spectrometer was used to characterize the coordination between liquid metal and oxygen in alumina.The thermal conductivity of compound thermal grease was measured by laser beam thermal conductivity tester.The volume resistivity of the sample was measured by a high resistance meter(2517 b).Finally,the corrosion test of pure liquid metal thermal conductivity paste and liquid metal/alumina/silicone oil thermal conductivity paste on copper sheet and aluminum sheet was observed by optical microscope.The effect of coordination between inorganic powder alumina and liquid metal on thermal conductivity and resistivity of liquid metal thermal conductive silicone grease was investigated.The results show that with the increase of liquid metal volume fraction,the thermal conductivity will increase and the electrical resistivity will decrease.When the filling amount of liquid metal/alumina thermal conductivity filler is 70vol% and the volume fraction of liquid metal and alumina is 80:20,the highest thermal conductivity is 3.274 W /(m·K),and the resistivity at this time is about 1.1*109Ohm·cm,which is an order of magnitude higher than that of pure liquid metal thermal paste with the same filling quantity.In addition,through the corrosion test found that liquid metal/alumina/silicone oil thermal paste for aluminum and copper are not found obvious corrosion,and pure liquid metal corrosion is more serious for aluminum,no obvious corrosion for copper.Finally,the aging test shows that the liquid metal/alumina/silicone oil thermal conductivity paste has good thermal stability.