Dynamic Thermal characterization of Thin Films via IR Thermography

This work presents a novel method for the thermal characterization of thin films via infrared thermography. In order to measure the thermal conductivity of a material, a temperature gradient has to be introduced. For this purpose, the films are suspended above rectangular and circular cavities in opaque substrates. The free-standing area of the films is heated homogeneously by a visible light source. In order to measure the resulting temperature distribution, a contact-free method is preferred, such as infrared microscopy. Under steady-state conditions, the measured temperature distribution can be fitted with an analytical model, yielding the in-plane thermal conductivity. The method can be extended by periodically heating the film and capturing the temperature distribution as a function of time. We develop a finite differences model with which not only the thermal conductivity but also the volumetric heat capacity and the effective total emissivity can be obtained from the time-dependent temperature measurement.