Lightweight and highly conductive carbon nanotube-copper composites

Abstract

From the perspective of the environmental impact, the need for a lightweight Cu substitute for wiring has been increasing to reduce CO₂ emissions and improve fuel efficiency in the fields of automobiles, aircraft and recently drones. Carbon materials, such as CNTs or graphene possess a light weight but show high electrical resistance due to the existence of crystal defect or electrical junctions. We have reported that the composite of CNTs and Cu combines light weight (40 % lighter than Cu) and high electrical conductivity comparable to Al or Au, making it a next-generation alternative to Cu. In addition, we found that the CNT-Cu composite shows higher electromigration resistance and smaller thermal expansion, suggesting the potential to improve the performance and stability of wiring materials in thermally or electrically harsh environments. In this paper, we introduce the unique performance of CNT-Cu composites, relating to their structural characteristics, and the manufacturing process by discussing the important role of uniform mixing of Cu and CNTs at the nanoscale.