Infrared Imaging Microscope as an Effective Tool for Measuring Thermal Resistance of Emerging Interface Materials

The reduction of interfacial resistance continues to be a significant challenge in thermal management of semiconductor and other microscale devices. Current state-of-the-art thermal interface materials (TIMs) have resistances in the range of 5–10 mm²·K/W. At these values, particularly for the emerging highly nonhomogeneous materials, standard measurement techniques often fail to provide accurate results. This paper describes the use of infrared microscopy for measuring the total thermal resistance across multiple interfaces. The method is capable of measuring samples of wide ranging resistances with thicknesses ranging from 50–250 μm. This steady-state technique has several advantages over other methods, including the elimination of the need for intrusive temperature monitoring devices like thermocouples at the area of interest and the need for a priori knowledge of the specific heat and density of the materials of interest, as in the transient techniques for determining thermal resistances. Results for three different commercially available TIM and uncertainty analysis are presented.