Research On Thermal And Electrical Characterisation Of Carbon Films

Carbon film is a kind of material with great development and application prospects.It is a thin film mainly formed by carbon atoms and has excellent physical and chemical properties,such as high thermal conductivity and excellent optical properties.Therefore,carbon film is widely used in heat dissipation materials,mechanical tools and device surface protective layers.Since the 20 th century,with the development of smart phones,smart bracelets and various microprocessors,people began to integrate more and more electronic devices on the substrate,in order to achieve high integration to achieve device performance improvement and portability.But the heat generated by high integration is one of the main problems that plagues and restricts the development of integrated technology.Therefore,scientists not only pay attention to the consideration of the heat density of the system in the design of equipment and devices,but also make continuous research breakthroughs in heat dissipation materials.Among them,carbon materials have been widely used in heat dissipation materials due to their high thermal conductivity.Aiming at the application trend of carbon film in heat dissipation field,this thesis focuses on the study of electrical and thermal properties of carbon film.The four probe method for measuring the resistivity of carbon film is improved,and a scheme for measuring the thermal conductivity of carbon film based on angstrom method is proposed.At the same time,a bending device is designed to bend the carbon film and detect the change of its characteristic.Firstly,the basic theory of the conductivity and thermal conductivity measurement techniques for carbon film and the corresponding model construction are described in detail,and then the constructed model is simulated by COMSOL to further optimise the design solution,completing the theoretical derivation and building a theoretical verification of the solution,further illustrating the rationality,feasibility and advantages of the design solution.Therefore,the metal Al electrode is formed by electron beam evaporation,and then the conductive silver paste is used as the connecting electrode of the external lead.Final test is carried out by the laboratory four probe tester,and the test error is successfully reduced to 3.8%.Based on angstrom method,the construction of thermal conductivity detection system is introduced in detail from three aspects: overall framework design,power supply design and temperature acquisition.At the same time,the thermal conductivity of carbon film is measured and analyzed,the influence of heat loss in the system is discussed,the performance of the detection system is analyzed and optimized,and the detection error is reduced to less than 5%.Finally,for the bending and folding of carbon films in practical applications,we further complete the design and construction of a reliability testing system,bending the carbon film several times before further testing the thermal and electrical conductivity in order to complete the measurement of the reliability of the material properties and give specific numerical images of the performance changes.Through this experiment,it can be seen that after many times of bending by the bending machine,the flexible carbon film has no drastic changes in the two characteristics of electrical resistivity and thermal conductivity.It shows that the reliability of the characteristics of the resistivity and thermal conductivity of the carbon film is good.It itself is a stable material at room temperature.In future applications,especially in the field of heat dissipation,it serves as a good radiator.The material,with its excellent thermal conductivity,high plasticity and good stability,is of great development and application value.