Measuring Thermal Diffusivity of Thin Films in Thickness Direction

Thin polymer films are widely used in electric and electronic industries, due to their outstanding electrical insulation properties. The accurate thermal parameters of thin film are beneficial to describe the thermal characteristics of electronic devices, which may improve their stability and service life. Therefore, it is important to measure the thermal parameters of thin films in high accuracy. We propose a novel method based on thermal response current to achieve the measurement of the thermal diffusivity of thin film with thickness several micrometers. In this paper, a two-layer sample structure is utilized, where one of the layers acts as the detector with known thermal parameters and the other as measured film. We record the thermal displacement current of the detector film and analyze the time-domain characteristics of the thermal displacement current. The temperature distribution in the two-layer structure and the displacement current by the thermal pulse exciting detector layer were simulated by numerical calculation, the optimal solution of the thermal diffusivity of the thin film is achieved through multiple iterations. This method can quickly measure the thermal diffusivity of thin film in thickness direction with high accuracy, especially suitable for polymer films with a thickness of a few microns.