Measurement of temperature conductivity of thin metal layers by laser flash method

Background. One of the key targets of power electronics is to provide an efficient heat removal in power semiconductor devices (PSD). The heat removal efficiency in PSD is significantly dependent on thermal conductivity of thin metal layers that are part of inter-cell connections of a device. Concerning this, it is of great significance to find methods of accurate measuring of temperature conductivity in these layers. The aim of the study is to develop a method of measuring temperature conductivity of thin metal layers in PSD production technologies, based on the laser flash method with the use of regular equipment. Materials and methods. The laser flash method (Parker method) was used to measure the temperature conductivity of copper and aluminum thin layers and, then, thin sintered layers of silver paste as well. Results. The paper describes the procedure of measuring by the laser flash method; the procedure is based on radial heat flows formed in thin metal layers that extend from the periphery to the centre of the sample. Mathematical modeling of heat transfer processes is presented. Using the setup LFA 427 (NETZSCH) the authors have determined coefficients of temperature conductivity of thin metal layers. Conclusions. The findings show that for accurate measurement of temperature conductivity in thin metal layers using a laser flash, unlike the standard Parker method, it is necessary to generate radial heat flows that extend to the centre of the sample in those layers. The reliability of the proposed methodology is proven by conformity of temperature conductivity results, obtained from measuring copper and aluminum samples, to look-up tables. The temperature conductivity of a thin sintered layer of silver paste, used in inter-cell connections of PSD, is calculated.