Obtaining Orthogonal Thermal Conductivity Components from Anisotropic Thin Films Using the Pseudo Steady-State 3ω Method

Abstract

Directional characterization of thermal conductivity is essential for the development of technologies, including electronic devices, as it allows for the optimization of heat management. With the miniaturisation of electronics, thin films of materials a few nanometres to a few microns thick are commonly used. Only a few methods exist to measure the orthogonal in-plane components of thermal conductivity in anisotropic films, and one that has recently been demonstrated is the pseudo steady-state 3ω method. In this work, a computational model of pseudo steady-state 3ω measurement chips has been developed and evaluated. Thin films of an anisotropic material are modeled with respect to the measurement of in-plane thermal conductivity in orthogonal directions. Through modeling the measurement of an anisotropic polymer film, it is found that this method can be remarkably accurate in obtaining the orthogonal components of thermal conductivity. The measurement error, caused by heat leakage at the edge of the measurement area, can be as low as 4%. The dependence on material and measurement parameters is discussed, and it is shown that the model can also be used to correct for the heat leakage at the edge of the measurement area.