Measurement of in-plane thermal conductivity of self-suspended thin films

Abstract

A method for in-plane thermal conductivity measurement of self-suspended thin films by steady-state infrared thermal thermography is introduced. Based on the one-dimensional heat conduction equation, a theoretical model of temperature distribution on the surface of thin film at steady state is established. The simulation results show that the error between in-plane thermal conductivity and theoretical value is less than 3% when the temperature rise of the film is less than 5K. By measuring the boundary temperature and thickness of the film, the in-plane thermal conductivity and emissivity can be obtained simultaneously without measuring the absorption of visible light by the film. Polyimide film with the thickness of 550 nm is experimentally investigated by this method. We find that the in-plane thermal conductivity is 2.15W/mK and emissivity is 0.93 by fitting temperature distribution curve. These results validate the method developed.