Effects of the Substrate Surface Morfology on the Porosity of Electroless Nickel Coatings

Electroless nickel (EN) plating is an autocatalytic chemical reduction process, the EN deposition developing in three dimensions during the plating. The substrate surface morphology determined by basis metal conditions and pretreatment process can significantly affect the porosity of the EN deposit. Models of EN deposition on different substrate surfaces were postulated based on the results of investigations by Scanning Electron Microscopy (SEM) and stylus 3D surface measurements. The postulated models indicate “morphology conflict” during EN plating. Examples of EN plating are given to confirm the postulated EN deposition models. The methods to reduce the porosity of EN and make high quality (pore-free) EN coating are discussed.