Dense Vertically Aligned Multiwalled Carbon Nanotube Arrays as Thermal Interface Materials

Carbon nanotube (CNT) arrays are being considered as thermal interface materials (TIMs). Using a phase sensitive transient thermo-reflectance technique, we measure the thermal conductance of the two interfaces on each side of a vertically aligned CNT array as well as the CNT array itself. We show that the physically bonded interface by van der Waals adhesion has a conductance $\sim$10$^{5}$ W/m$^{2}$K and is the dominant resistance. We also demonstrate that by bonding the free-end CNT tips to a target surface with the help of a thin layer of indium weld, the conductance can be increased to $\sim$ 10$^{6}$ W/m $^{2}$K making it attractive as a TIM.