Superior Thermal Interfaces Made by Metallically Anchored Carbon Nanotube Arrays

Vertically aligned carbon nanotube arrays (CNAs) have received much interest for thermal interface applications due to the extremely high thermal conductivity of carbon nanotubes (CNTs) and the compliant mechanical properties of the CNA film. The challenge has been the big contact thermal resistance between the CNA tips and the opposing surface, which has resulted in the overall thermal performance of CNA TIMs far below expectation. We developed a process to metalize the CNA tips, and then firmly weld the tips to the back side metal of the SiO₂/Si substrates using indium solder. We achieved close to 1 mm²K/W total interface thermal resistance (1.4 mm²K/W estimated from infrared thermal microscopy and 1.3±0.3 mm²K/W measured using a 3-omega method) with nearly zero compression pressures. This thermal resistance value is about one order of magnitude smaller than that of the thermal interfaces used for the state-of-the-art microprocessors.