Estimating the Thermal Conductivity of Thin Films: A Novel Approach Using the Transient Plane Source Method

Abstract

The conventional transient plane source (TPS) method for thin films is used for films and adhesives with thicknesses between 50 and 200 µm. However, measuring the thermal conductivity of thin films with the conventional TPS method is inaccurate due to thermal contact resistance between the insulating sensor layers, the film and the sensor, and the film and the background material. A new approach to measuring thin films with the TPS is introduced, where the heat flow is constrained to one dimension, and a slab layer made from the same background material is introduced between the thin film and the TPS sensor. This decouples the effects of the thermal contact resistance (TCR) of the sensor to the thermal resistance of the film. The new approach is tested on four different thin films with stainless steel as the background material. The results are compared to guarded heat flow meter measurements. Excellent agreement (< 12% error) between the two methods is achieved, showing that the new method proposed is fast, accurate, and convenient alternative for determining the thermal conductivity of thin films.