Study On Copper/Diamond Heat-dissipating Composite Material Prepared By Powder Metallurgy Technology

With the rapid development of many fields like modern microelectronic devices,aerospace,defense technology and so on,electronic device integration technology is more extensively used,but the improved temperature of electronic devices with highly integrated,which is caused by excessive heat during the process of application,will be easy to cause damage to the devices,so it is a potential risk.At the same time,the lack of heat dissipation capacity hinders the further improvement of the performance of electronic devices seriously.In order to improve the safety and working life of electronic devices,it is necessary to improve the heat dissipation function of electronic devices and the heat dissipation efficiency of operating devices.However,metal heat dissipation materials such as aluminum and copper which are of common application in the field of electronic devices at present can no longer meet the need of high heat dissipation of new electronic devices.Therefore,it is a research focus to develop the heat dissipation materials with lower coefficient of thermal expansion(CTE)and higher coefficient of thermal conductivity(TC)in the field of semiconductor heat dissipation materials currently.The thermal conductivity of diamond which is a kind of semiconductor is the highest of solid materials.The thermal conductivity of diamond is 2000 W/m·K,which is far more than that of various metals.It is the best choice for diamond film as a kind of heat dissipation material.However,the application range is greatly limited by low production efficiency and high cost of diamond film.Diamond single crystal particles show good heat dissipation performance itself,but they cannot be used alone in the field of heat dissipation.However,they can be combined with metals such as aluminum and copper to prepare metal-based composite heat dissipation materials.The aluminum carbide phase generated at the interface of diamond-aluminum composite is easy to hydrolysis,which limits the application of this kind of material.In recent years,because of high thermal conductivity and good chemical stability of copper,diamond/copper composite heat dissipation materials have been widely focused and developed.At present,the feasible technical method is to prepare diamond/copper composite materials by air pressure infiltration.Although it is a better solution for the problem of efficient heat dissipation of high-power devices,the disadvantages of the higher production cost and the thicker heat dissipation material prepared is(About 4 mm)make this method can not be applied to some small devices.However,a large number of miniaturized and integrated electronic devices are in great need of suitable sheet heat sinks.Therefore,it is urgent to develop and prepare thin sheet heat dissipation substrate by the use of powder metallurgy technology which is of great development potential.for current engineering applications.Therefore,a kind of powder metallurgy preparation process for copper/diamond heat-dissipating composite material is designed to conduct a full range of research from the aspect of "material-metallurgy-process" in this paper,this method systematically investigates various factors such as the quality of raw materials,copper matrix alloying,copper/diamond interface metallization,sintering process parameters(temperature-pressure-time)and secondary vacuum high temperature sintering on the sintered structure and heat dissipation performance of composite heat dissipation materials.The study found that the oxygen content of the raw copper powder has a great influence on the structure and performance of the sintered matrix.When the oxygen content of the copper powder is reduced from 858 ppm to 116 ppm,the powder sintering activity is enhanced,the sintering structure performance is greatly improved,and its thermal conductivity is increased from 126 W/m·K to 328 W/m·K.The heat dissipation sample is prepared by reduction of copper powder and titanium-coated diamond(with a volume concentration of 80%)mixed and sintered,and its thermal conductivity can reach 417 W/m·K.During hot-pressing sintering,with the extension of sintering temperature,pressure and high-temperature holding time,the density and thermal conductivity of the copper/diamond composite sintered body increase to varying degrees,but they all have suitable parameter ranges.In order to enhance the alloying ability of the copper matrix,a small amount of low-melting tin is added into the matrix in the form of bronze powder,which can improve the sintering density of the sample to a certain extent.After the hot-press sintered copper/diamond composite sintered body is treated by vacuum high-temperature sintering,the fusion growth of the grain boundary for the copper matrix structure can increase to a certain extent,the decreases number of grain boundaries can improve the thermal conductivity.