Ultrasonic Welding of Bulk Carbon Nanotube Conductors

Incorporation of bulk carbon nanotube (CNT) conductors into energy and data systems can require new methods of making a functional interface with low electrical contact resistance and high mechanical strength. Ultrasonic welding has been shown as a viable technique for mechanically and electrically bonding commercial CNT materials (CVD) to copper foil. The mechanical strength across the ultrasonic welds was measured via dynamic mechanical analysis with single lap welds exceeding 350kPa. The electrical properties of the ultrasonically welded bulk CNT conductors (chemically doped with KAuBr4) to Cu were measured via 4-point probe and show specific contact resistance between the CNTs and copper as low as 4.3mcm(2). Thus, ultrasonic welding represents a mechanically robust method for making functional contacts between bulk CNTs and metallic interconnects with a low contact resistance. In addition, ultrasonic welding was successfully used to join two CNT ribbons end-to-end (breaking strength of single lap welds exceeding 200kPa) demonstrating that it is also a viable technique for making larger dimension CNT materials from smaller components.