Characterization Methods for Solid Thermal Interface Materials

Thermal interface materials (TIMs) play a major role in the performance of semiconductor devices by optimizing the thermal contact between device and heatsink. Their influence is further increasing with the usage of novel chip materials such as SiC and GaN. In this methodology study, we compared five of the most established evaluation methods for solid TIMs with each other: transient plane source, LaserFlash, DynTIM, TIMA, and an application-oriented R_{\mathrm{ th}} measurement system. We investigated a wide range of typical TIMs in order to explore the limits of the different measurement systems. The results show that, despite existing norms, the used characterization method has a significant influence on the measured thermal conductivity. We also show that the temperature and pressure dependence has a significant influence on the thermal performance of TIMs and that these data need to be included in device specifications. Additionally, detailed error analysis and discussion about sample selection, error influence, and measurement effort for the presented methods are given.