化学镀镍诱发过程的研究 II.用电子能谱研究诱发过程

Studies of inducing process of electroless nickel plating ii. Research of inducing process by electron spectroscopy

In the previous paper, it was reported that a sudden decrease down to -0.6V and lower in stationary potential was observed from the stationary potential-time curve and the reaction of electroless nickeling could be induced by metallic iron catalyst when it was in contact with substrate metallic copper. In this paper, AES and XPS surface analysis and depth profile technique was employed to investigate the surface and depth distribution of Ni, Cu, Fe and P in the nickel coating deposited on the substrate metal. The experimental results showed that there was a thin adsorption layer consisting of C, S and Cl. The pure electroless nickel deposition, its Ni/P ratio being about two, existed under the adsorption layer. A layer with rapidly changed Ni/P ratio occurred close to the surface of substrate metal, under this layer the substrate metal was alloyed with Ni and P, thus becoming Cu-Ni-P alloy. The ratio of components in this alloy was found to be Cu:Ni:P=56:36:5. This fact explained why the electroless nickel deposition can preferably adhered to the substrate metal. In inducing process, Fe was not detected by AES from the substrate metal and nickel deposition. Thus it showed that the inducing reaction takes place without the deposition of inducing metal.