Tert-Butylamine borane as a reductant in electroless nickel plating for improved etch resistance in the electrolyte

Abstract

An Ni–B coating was developed on a copper substrate by the direct electroless technique and from a plating bath containing tert-butylamine borane (TBAB). The influence of the electroless plating conditions, using TBAB as a reducing agent on the composition, surface morphology, high-temperature stability and etch resistance in the electrolyte of the coatings, was investigated. The resulting electroless Ni–B plating surfaces were examined and characterized by scanning electron microscopy and X-ray fluorescence spectroscopy for morphology and chemical composition, respectively. Electrochemical characterization by potentiodynamic polarization confirmed that a 0.1 M nickel concentration bath for the Ni–B plating was optimized by a TBAB concentration of 0.03 M, temperature of 60°C and pH of 8. Under the optimal bath conditions, the Ni–B electroless plating layer exhibited superior etch resistance in the electrolyte as well as improved stability at high temperature than the Ni–B electroless plating layer prepared using dimethylamine borane. Hence, owing to the remarkable properties of the Ni–B electroless plating layer, this fabrication technique that employs TBAB can be extended to fabricate other Ni–B electroless plating layers.