The effect of bath conditions on the electroless nickel plating on the porous carbon substrate

Abstract

Electroless nickel plating is widely used technique in industries. In most cases, electroless nickel plating was applied on the open surfaces and the rate of deposition was controlled with temperature and time. However, when the electroless plating is applied on the porous carbon, the rate of deposition is also dependent on the activation process. In this research, electroless nickel plating on the porous carbon was investigated. The porous carbon was selected as the substrate. The pore sizes of carbon substrates were 16–20 μm and over 20 μm. Since hydrophobic surface prevented the penetration of solution into porous carbon, the carbon surface changed from hydrophobic to hydrophilic after immersing the substrate in an ammonia solution at 60 °C. The alkaline bath and acidic bath were used in electroless nickel plating. The pHs were 9–11 in alkaline bath and 4–5 in acidic bath. The content of phosphorous in nickel deposit was higher in acidic bath than that in alkaline bath. As increasing pH in each bath conditions, the content of phosphorous in nickel deposit was decreased. The rate of electroless plating in alkaline bath was faster than that in acidic bath. The minimum concentration of PdCl 2 for the electroless nickel plating was 10 ppm in acidic bath and 5 ppm in alkaline bath. The thickness of nickel was not significantly affected by the concentration PdCl 2.