Study on the Accelerating Effect of Anodic Treatment on Electroless Nickel Plating Process

Abstract To accelerate the electroless nickel plating (ENP) process at a moderate temperature (75°C), the effect of anodic treatment on the deposition rate was investigated. Firstly, the influence of anodic treatment time on the deposition rate was explored. Subsequently, open-circuit potential (OCP) and linear sweep voltammetry (LSV) techniques were used to study the influence of anodic treatment on ENP initiation time and the cathodic deposition of nickel. Finally, scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the surface morphology of the coating, elemental composition and chemical valence state before and after anodic treatment, respectively. The results show that anodic treatment accelerates the ENP process remarkably: after 20 s of treatment, the coating thickness rises from 1.301 to 1.741 μm (a 34% increase), and the ENP initiation time is reduced from 76.8 to 41.0 s. Anodic treatment elevates the cathodic reduction current of nickel ions and increases the phosphorus content in the coating from 7.88 to 8.90 wt %. Anodic treatment leads to an increase in the intensity of the NiO and Ni3(PO4)2 signals. In conclusion, anodic treatment improves the ENP deposition rate through hypophosphite ion enrichment and accelerated electron release.