Preparation of Nickel Hypophosphite for a Long-Life Electroless Nickel Plating Bath.

Nickel hypophosphite (Ni (H2PO2)2) was prepared by a direct (ion-exchanging) method and a double decomposition method. These two methods were compared in terms of use in manufacturing. Using the direct method, nickel hypophosphite was obtained with greater purity without generation of a by-product. In addition, hypophosphorous acid obtained through the direct method is a component of nickel hypophosphite that serves as a chemical for creation and supply of the plating bath. In this study, therefore, nickel hypophosphite prepared by the direct method has been used to evaluate the newly developed plating process. Deposited films obtained by this plating process were superior to those produced by the conventional plating process using sodium hypophosphite and nickel sulfate. Films produced by the new process revealed less internal stress, a result that could lead to longer life for the plating bath. Also, the newly developed plating process demonstrated a deposition rate similar to that of the conventional process.Results indicated that this newly developed plating bath is suitable for practical use due to advantages of bath stability and easy handling.