Preparation And Thermal Conductance Research Of Graphite Film By Graphene Oxide

With the rapid development of microelectronics integration and assembly technology and the integrated use of high power-density devices, electronic instruments and equipment are more integrated, miniaturized and high densified. When the power density and heat of the electron device is gradually increasing, the heat dissipation has become the key issue for the electronic products. Graphite films used as heat spreader are widely concerned recently due to its advantages of high thermal conductivity, low thermal expansion coefficient, low thermal resistance, light weight and so on. In particular, graphene found in recent years, has potential application in the thermal management of electronic products. In this paper, we used graphene oxide as raw material to prepare graphite film by coating method. The processing parameters, the effect of heat treatment on the thermal conductance of graphite film are intensively studied. Moreover, the cooling effect of as-prepared graphite films was tested and analyzed.Firstly, the graphene oxide prepared by the modified Hummers method was used as raw material, and the film was prepared by the coating method. The processing parameters were intensively studied. The results showed that the substrates, the concentration of graphene oxide solution, the coating thickness and the drying degree greatly determined the uniformity, roughness and thermal diffusivity of the graphite film. 1) Substrates such as B substrate, which has smooth surface, should be used in the preparation of graphite film by the coating method. 2) The concentration of graphene oxide solution should be controlled at 20-35mg/m L, so that the graphene oxide can be easily coated on the substrate. 3) With these condition of reducing agent concentration 40mg/L, reducing time 4h, and slow heating rate, the prepared graphite film has better uniformity and high thermal conductance performance.Secondly, heat treatment has great effects on the microstructure, thermal conductance and electric conductivity of the graphite film. It showed that the high temperature heat treatment resulted in the formation of a large number of bubble bumps on the surface of the graphite film, which increased the distance of graphite layers. At the same time, the oxygen containing groups in the graphite film were further reduced at high temperature, the thermal diffusivity increased and the electric resistivity decreased.Lastly, the cooling effect of graphite film was tested and analyzed. By using ceramic heating module as simulated chip, as-prepared graphite films can decrease the temperature of simulated chip in ~5oC. By bonded to the surface of chipsets in one smart phone, as-prepared graphite film could decreased the temperature of chipsets in ~3oC with the full working loading of chipsets. Both of them showed that the graphite film prepared in this work has great potential application in the thermal management field of electronic products.