Electroplating of Cu-NT onto metallic substrates

This investigation has achieved semi-uniform coatings of single-walled carbon nanotubes (SWNT) onto copper substrates by electrodeposition from a metallic plating bath as well as electrophoretic deposition. Furthermore, SWNT mat was used as an electrode in which metallic ions were electrodeposited. CVD-produced SWNT were functionalized via agitation concentrated sulfuric acid/nitric acid. FTIR studies confirm the presence of carboxylic and hydroxyl groups on COOH-SWNT. COOH-SWNT were ultrasonicated in cetyl trimethylammonium bromide (CTAB), a cationic surfactant which lends a positive charge. The suspension was added to Cu and Ni metallic plating baths. Electrolytic deposition was carried out on plating baths containing COOH-SWNT. In addition, electrophoretic deposition was performed using COOH-SWNT dispersed in aqueous solutions of CTAB. Scanning Electron Microscope/Focused Ion Beam (SEM/FIB) was implemented to characterize nanotube dispersion as well as plating deposition, uniformity and morphology. SEM imaging of FIB cross-sections show limited uniformity of nanotube coatings, with agglomerations of varying sizes, depending on the nature of the deposition. Also observed is a morphological conformation of metallic ions to deposited COOH-SWNT. Finally, metallic deposition onto SWNT mat shows a uniform metallic layer on the surface as well as metallics within the nanotube matrix, indicative of diffusion occurring during the plating process. Current studies focus on the electrical performance of iso-metallic SWNT (iso-M-SWNT) as well as metallic substrates coated with pristine or COOH-SWNT. Contact resistance measurements were performed on iso-M-SWNT mat with a soft Au ball as the probe. Iso-M-SWNT mat containing 70% metallic nanotubes exhibit resistance values of approximately 450 mOhm upon a maximum force of 50 cN. The morphological and electrical characterization reported here was performed in an effort to enhance uniformity and dispersion of nanotube-plated metals.