New level of accuracy in TIM measurements

The thermal management of semiconductor devices and systems has become a widely discussed topic over the past decades due to the ever increasing integration and the resulting power densities inside the packages. The increasing junction temperature is a great threat for the operation and the long-term reliability of the packaged device. One of the most important barriers in the heat conduction path is the thermal interface material. Their thermal performance significantly influences the overall thermal resistance of a system from the junction to the ambient. In this paper two approaches are described for the accurate thermal conductivity measurement of these materials; both techniques were developed in the framework of the European Nanopack project. One of them is a highly accurate, scientific method which benefits from the improvements of the semiconductor industry: the TIM is measured between two bare sensor chip surfaces. The other method is based on thermal transient testing and allows the measurement of a given grease or paste in its real environment. Both of them are capable of the measurement of highly conductive, nanoparticle based TIM materials. In this paper these two methods are explained in more details and measured results are compared with each-other. The effect of the measurement arrangement on the measured thermal resistance values is also discussed.