The Study Of Thermal Conductivity Of Mcro-And Nano-Carbon Materials Doped Composite Material

With the development of technology, the performance of microelectronic devices is improved rapidly. However, as the power density of the microelectronics devices is increasing continuously, thermal dissipation in high density microelectronic devices becomes vital to ensure the reliability of these devices. With the demand of high-density, miniaturization and low-cost for microelectronic devices, package materials with higher performance become more and more important. Due to its high thermal conductivity and electrical permittivity, Al N thin film has been investigated as a candidate packaging material. On the other hand, because of good mechanical and electrical insulation properties, epoxy resin is widely used as packaging materials in microelectronic devices and LED. Nevertheless, Al N thin film or epoxy resin generally exhibit low thermal conductivity. Doping with high thermal conductive micro- or nano-size materials has been proved to be an effective way to improve the thermal conductivity of materials. And as we know, both carbon nanotube and diamond powder show high thermal conductivity.Based on the analysis above, this thesis investigated the high thermal conductivity of Al N thin film and epoxy resin doped with micro- and nano-size carbon materials(carbon nanotube, diamond powder). Theoretic models have been established to explain the experimental results. And this thesis includes the following parts:1. Polymer assisted deposition have been used to fabricate AlN thin films undoped and doped with micro- and nano-size carbon materials on Si(100) substrates. The structure and composition of the undoped and doped Al N thin films have been studied by XRD and XPS, and the effective thermal conductivity of thin films has been tested by self-assembled 3ω devices.2. Polyethyleneimine and mixed concentrated acid solution have been used to treat CNTs whereas HF acid has been used to treat diamond powder. Composites of carbon material and epoxy resin have been formed by in-situ composite technical. Fracture surface of the composites and the distribution of the carbon materials in epoxy resin have been examined by SEM, and the effective thermal conductivity of the different composites has been characterized by the laser flash method.3. Both effective medium theory and percolation theory have been discussed for theirapplication in the calculation of effective thermal conductivity of the composite materials. Based on the study of the advantages and disadvantages of these models, a new function has been established to include the different factors in calculation of effective thermal conductivity of composite materials. It is proved the proposed function can fit our experimental data very well.