Nanowire-Polymer Nanocomposites as Thermal Interface Material

Packaging of semiconductor electronic device is a challenge due to the progressive increase in the power level of operating devices which is associated with the increasing device performance. As semiconductor device feature sizes continue to be reduced, ensuring reliable operation has become a growing challenge. The effective transfer of heat from an integrated circuit (IC) and its heat spreader to a heat sink is a vital step in meeting this challenge. The ITRS projected power density and junction-to-ambient thermal resistance for high-performance chips at the 14 nm generation are >100 Wcm-2 and <0.2 °CW-1, respectively. The main bottlenecks in reducing the junction-to-ambient thermal resistance are the thermal resistances of the thermal interface material (TIM) (Prasher 2006) and the heat sink. The primary goal of this chapter is to review the metallic-nanowire nanocomposites as thermal interface material compared to other types of thermal interface materials. The first section of the chapter will review different types of nanowire-polymer composites as well as carbon nanotube-polymer composites as thermal interface material. In recent years, carbon nanotube (CNT) and nanotube-polymer composites were proposed in many publications as a possible TIM with high thermal conductivity and low thermal impedance. However, the possibility of inadvertently incorporating contaminating impurities, the existence of voids between CNTs, and the growth conditions of CNT arrays greatly affect the effective thermal conductivity of CNTs, typically resulting in a TIM with a large performance uncertainty. On the other hand, nanowire-polymer nanocomposites can be proposed as thermal interface material where due to the inclusion of nanowires, composites should achieve high thermal conductivity. The later sections of this chapter will describe the research and development ongoing in the area of nanowire-polymer nanocomposites. The fabrication routes for the nanowires and the nanowire-polymer composites as well as the characterizations of the nanocomposites will be discussed in detail. The applicability of metallic nanowire-polymer nanocomposites as thermal interface material will be evaluated.