THE SKILLS FOR MEASURING THE EFFECTIVE THERMAL DIFFUSION CONDUCTIVITY OF THE VAPOR CHAMBER WITH THE ÅNGSTRÖM THEORY

Abstract

Most people measure the thermal resistance of vapor chambers by using Fourier's law of thermal conduction. However, Fourier's thermal conduction law is generally applied when the evaporator area is the same as that of the condenser, and this is completely different from the realistic condition; that is, the heated area of the evaporator is much smaller than the condenser area. Therefore, we proposed a new method to initially measure the thermal diffusivity of the test sample by the Ångström theory and then convert it into effective thermal diffusion conductivity of the vapor chamber. The Ångström theory is originally used for the one-dimensional test sample. However, the results of measurements that are applied to heat spreaders such as vapor chambers, heat pipes, or graphene are generally not accurate enough. The reason is that some test samples are not one-dimensional, or the test skill is not high. Therefore, the accuracy of measuring the effective thermal diffusivity of vapor chambers is very important for identifying the performance of the vapor chamber. The method in this paper using the Ångström theory has successfully divided the size of the current vapor chamber into three zones by the method of thickness-to-width aspect ratio. The repeatability error of obtained data is less than 5%, and the accuracy error is less than 10%.