To achieve denser and taller carbon nanotube (CNT) arrays on Cu foils, catalyst and chemical vapor deposition (CVD) conditions were carefully engineered. CNTs were grown to ∼50μm using Fe/TiN/Ta catalysts in which Ta and TiN acted as diffusion barriers for Cu and Ta, respectively. A tradeoff was found between the mass density and height of the CNTarrays, and CNTarrays with a mass density of 0.30 g cm<sup>-3</sup> and height of 45μm were achieved under optimized conditions. Thermal interface materials (TIMs) with CNT array/Cu foil/CNT array structures showed decreasing thermal resistance from 86 to 24mm<sup>2</sup>KW<sup>-1</sup> with increasing CNT array mass densities from 0.07-0.08 to 0.19-0.26 g cm<sup>-3</sup> for Cu and Al blocks with surfaces as rough as 20-30 μm. The best CNT/Cu/CNT TIMs showed thermal resistance values comparable to that of a typical indium sheet TIM.
ASJC Scopus subject areas
- Physics and Astronomy(all)