Palladium thiolate bonding of carbon nanotube thermal interfaces

Abstract

Carbon nanotube (CNT) arrays can be effective thermal interface materials with high compliance and conductance over a wide temperature range. Here, we study CNT interface structures in which free CNT ends are bonded using Pd hexadecanethiolate, Pd(SC₁₆H₃₅)₂, to an opposing substrate (one-sided interface) or opposing CNT array (two-sided interface) to enhance contact conductance while maintaining a compliant joint. The Pd weld is particularly attractive for its mechanical stability at high temperatures. A transient photoacoustic (PA) method is used to measure the thermal resistance of the palladium-bonded CNT interfaces. The interfaces were bonded at moderate pressures and then tested at 34 kPa using the PA technique. At an interface temperature of approximately 250°C, one-sided and two-sided palladium-bonded interfaces achieved thermal resistances near 10 mm² K/W and 5 mm² K/W, respectively.