Freestanding Sensor-Based 3? Method For Characterization Of Thermal Conductivity And Thermal Boundary Resistance In Micro-nano Structures

In the process of miniaturization and precision of equipment development,it is a necessary condition to scientifically guide thermal management and thermal design of micro-nano structure.The freestanding sensor-based 3?method is considered as an effective measure of thermophysical parameters.It has been widely used and deeply studied in the measurement of thermal properties of thin film materials,fiber materials and powder materials.Firstly,according to the theory and experimental principle of 3?method,a set of 3?harmonic testing system for different structure types of sensor is set up,which can achieve wider frequency range and more stable test and computer control of experimental process.The test system was verified with the thermal conductivity of standard samples such as test air,ethanol,ethylene glycol and deionized water.Then,the theoretical model of the thermophysical properties of the multi-layer thin film was measured by the 3?method.The thermal conductivity,thermal diffusivity and thermal boundary resistance of the SiO₂/ZrO₂/Nd:YAG multilayers were measured.The current test of the thermal conductivity of thin-film structures using more photothermal reflection method based on the short pulse laser or micro-machining of suspended micro-device method,experimental equipment and sample processing are very complicated.3?method to measure the structure of the membrane attached to the sample surface using the metal strip as a freestanding sensor,the preparation process is relatively simple.The experimental results are close to the references of the literature,which verifies the reliability of the experiment.Secondly,based on the principle of measuring the thermophysical properties of fibrous materials by 3?method,the thermal conductivity of SiC fibers was measured.When the SiC fiber is connected to the electrode of the test circuit,there is an thermal boundary resistance at the contact point between the fiber and the metal.By testing the thermal conductivity of fibers of different lengths,the thermal boundary resistance of the test structure is fitted.The thermal boundary resistance occupies a large proportion of the thermal resistance of the entire test structure and can not be ignored in the process of experimental measurement.Finally,the real thermal conductivity of SiC nanoparticle powders was measured based on the principle of measuring the thermophysical properties of powder materials by 3?method.In addition,the self-thermal conductivity of SiC nanoparticle has been simulated with the equilibrium state method of MD molecular dynamics simulation.According to the relationship between the thermal conductivity of each phase in the mixed material system and the thermal boundary resistance,the experimental data obtained from the experiments and simulations were used to determine the thermal boundary resistance of SiC nanoparticle powders.