Electrodeposition and Characterization of Nanocrystalline Ni-NbOx Composite Coatings from Glycol-based Electrolytes for High Temperature Electronics Packaging

Ni-NbOx nano-composite coatings on Cu, from glycol-based electrolytes consisting of NbCl5, NiCl2 center dot 6H(2)O and propylene glycol. The effects of both cathodic current density and metal electrodeposition bath concentrations on the surface morphology and composition of the coating were examined. The highest relative metal percentage of co-deposited Nb was 14.3 at% obtained at a current density of 400 mA/cm(2). Scanning transmission electron microscopy (STEM) revealed a nanocrystalline FCC Ni structure without any significant lattice distortion, as well as an as-yet-unidentified compound. STEM X-ray mapping suggests Nb and O were uniformly distributed in the Ni matrix, without any significant phase segregation, which is consistent with XPS compositional depth profiling. Also, according to the XPS spectra, a 0.7 eV shift to lower binding energy for the Nb (V) species may suggest the partial chemical reduction of Nb2O5 due to possible Ni-Nb bonding. It is thus proposed that a Ni-NbOx deposit was formed by two parallel electrochemical reduction routes: 1) deposition of Ni metal; 2) deposition of a Ni-Nb-O compound as nano-clusters. (C) 2014 The Electrochemical Society. All rights reserved.