Design And Fabrication Of High Thermal Conductivity Al/In Lamellar Composite Structure

With the increasing power density of electronic devices,the trend of electronic devices is miniaturization,integration and high power,heat generation is also increasing gradually,the heat dissipation of electronic devices becomes more and more important.The interface between heating element and heat sink element is not close enough because of the roughness,which leads to a large interface thermal resistance,and the heat dissipation effect of the equipment is greatly reduced.The thermal interface material can increase the actual contact area by filling the gap of solid contact surface,reduce the interface thermal resistance and enhance the heat transfer efficiency.Commonly used thermal interface materials in the market mainly polymer-based,representative products are thermal silicone,thermal gasket and thermal adhesive,but the thermal effect is general.This thesis is devoted to the design and development of new metal thermal interface materials to effectively reduce the interface thermal resistance,the main research contents include:(1)Three kinds of porous aluminum foils with different pore sizes(20μm,50μm and 80μm)were prepared by laser drilling technique.The pore spacing was 100μm and the thickness of aluminum foils was 0.12 mm.The indium foil and the porous aluminum foil superposition place,the order is indium foil-the porous aluminum foil-indium foil,presents the sandwich structure.Al/In composites were prepared by vacuum hot-pressing,and the hot-pressing temperature,micropore size and thickness of indium foil were changed respectively.The results show that the combination of indium foil and porous aluminum foil is good.When the hot-pressing temperature is 150℃,the thickness of indium foil is 0.2 mm and the micropore size is 50μm,the thermal conductivity of the composite is up to 93.141 W/(m·K),which is close to the theoretical value.(2)The thermophysical properties and reliability of Al/In composites were studied.In order to verify the actual heat conduction effect of the Al/In composite,the Al/In composite was placed between the aluminum sheets to prepare a three-layer structure sample,and the thermal conductivity of the sample was measured by laser flash method,and the interfacial thermal resistance was calculated,at the same time,compare three commercial products on the market.The results show that the overall thermal conductivity of the three-layer structure sample is up to 157.8 W/(m·K),which is close to the thermal conductivity of pure aluminum,and is obviously higher than that of other commercial products.The remelting experiments of Al/In composites with different micropore size and thickness of indium foil were carried out,and the surface changes were observed at 160℃,180℃and 200℃,respectively.The results show that the indium in Al/In composite does not leak out at high temperature,and the micropores can adsorb indium in liquid state.(3)Al/In52Sn48 Composites were prepared,and the thermo-physical properties and reliability of Al/In52Sn48 Composites were studied.The results show that because the hardness of indium tin foil is higher than that of indium foil,only a small amount of indium tin is hot pressed into the micropores,and the thinner the indium tin alloy is,the worse the effect is.In the remelting experiment,the laser micropores also restrict the In52Sn48 alloy in liquid state.Because the hardness of In52Sn48 alloy is one order of magnitude higher than that of indium,there is a large gap in preparation.The overall thermal conductivity of the sandwich structure with Al/In52Sn48 composite is unstable.