Jose Ordonez-Miranda(1),*, Sebastian Volz(2), Mohamad Abo Ras (3)
(1) Institut Pprime, CNRS, Université de Poitiers, 86962, Futuroscope, France
(2) Laboratoire EM2C, CNRS, CentraleSupélec, Université Paris-Saclay, 92295 Chatenay, France
(3) Berliner Nanotest und Design GmbH, Berlin, Germany
*email@example.com, Tel: +33 684107141
Thermal interface materials, such as thermal pastes, are critical for optimizing the thermal contacts between two surfaces and improving the heat dissipation across them. In this work, the effective thermal conductivity of sintered porous pastes of silver is modeled through two theoretical methods and measured by means of three experimental techniques. The first model is based on the differential effective medium theory and provides a simple analytical description considering the air pores like ellipsoidal voids of different sizes, while the second one arises from the analysis of the scanning-electron-microscope images of the paste cross-sections through the finite element method. The predictions of both approaches are consistent with each other and show that the reduction of the thermal conductivity of porous pastes can be minimized with spherical pores and maximized with pancake-shaped ones, which are the most efficient to block the thermal conducting pathways. A thermal conductivity of 151.6 Wm–1K–1 is numerically determined for a sintered silver sample with 22% of porosity. This thermal conductivity agrees quite well with the one measured by LaTIMA for a suspended sample and matches, within an experimental uncertainty smaller than 10%, with the values obtained by means of Raman thermometry and the 3w technique. The consistence between our theoretical and experimental results demonstrates the good predictive performance of our theoretical models to describe the thermal behavior of porous thermal interface materials and to guide their engineering with a desired thermal conductivity.
 J. Ordonez-Miranda, et al., Int. J. Thermal Sci., 108, 185-194, 2016.
 J. Ordonez-Miranda, J. J. Alvarado-Gil, J. Mater. Sci., 47, 6733-6740 2012.