Measurement Techniques for Thermal Conductivity and Interfacial Thermal Conductance of Bulk and Thin Film Materials

Thermal conductivity and interfacial thermal conductance play crucial roles in the design of engineering systems where temperature and thermal stress are of concerns. To date, a variety of measurement techniques are available for both bulk and thin film solid-state materials with a broad temperature range. For thermal characterization of bulk material, the steady-state method, transient hot-wire method, laser flash diffusivity method, and transient plane source (TPS) method are most used. For thin film measurement, the 3x method and the transient thermoreflectance technique including both time-domain and frequency-domain analysis are widely employed. This work reviews several most commonly used measurement techniques. In general, it is a very challenging task to determine thermal conductivity and interfacial thermal conductance with less than 5% error. Selecting a specific measurement technique to characterize thermal properties needs to be based on: (1) knowledge on the sample whose thermophysical properties are to be determined, including the sample geometry and size, and the material preparation method; (2) understanding of fundamentals and procedures of the testing technique, for example, some techniques are limited to samples with specific geometries and some are limited to a specific range of thermophysical properties; and (3) understanding of the potential error sources which might affect the final results, for example, the convection and radiation heat losses.