Direct electroless nickel plating on copper circuits using DMAB as a second reducing agent

Generally, palladium catalyst treatment is applied to initiate the electroless Ni-P plating on the copper patterns because copper does not have a catalytic action for the oxidation of hypophosphite. However, when electroless nickel films are deposited on circuit boards with high density copper patterns by this process, many extraneous deposits are observed after electroless nickel plating. If electroless nickel plating is progressed on the copper patterns without palladium catalyst treatment, extraneous nickel depositions are inhibited. Direct electroless nickel plating of the copper patterns by the addition of dimethyl amine borane (DMAB) as a second reducing agent into the plating bath is investigated