Electroless Nickel-Phosphorus Plating (KFJ-20) on Copper and Iron Substrates

Abstract

Electroless Nickel (EN) plating is an autocatalytic method, a chemical reduction of a nickel ion in an aqueous solution with the presence of reducing agent that contain sodium hypophosphite (SHP) and where the deposition occurs without the use of electric current. The electroless Ni-P needs to be deposit onto copper but due to passivity of the metal, pretreatment and activation of copper surface need to be carried out. Thus, the optimum operation condition of Ni-P bath, palladium activator and deposition rate of Ni–P were studied. There are two substrates chosen for this study, namely iron and copper, to be coated by nickel. The source of Nickel is from KFJ-20 (Uyemura, Japan). KAT-450 activator which contained the palladium was used to generate active sites on the copper surface and also assist the nickel to deposit on copper substrate. Before undergo plating process, the iron and copper substrate undergo pre-treatment process such as cleaning, soft-etching, acid dipping and activation. Ni-P deposited on iron and copper substrate in order to distinguish the effectiveness of palladium as an activator. The optimum deposition condition was found to be on iron substrate at pH 7.5 while copper substrate at pH 5 with 3 min dipping time in activator, 20 min deposition time and 98.0 ˚C bath temperature. This indicate that palladium activation (KAT-450) is a good activator that can deposit nickel onto copper substrate. We also observed the deposition of nickel in a uniformly nodular and no cracking on the surface by field emission scanning electron microscope (FESEM)