Effect of Brighteners on the Deposits in the Nickel Citrate Electroplating

Authors developed a new electric nickel plating bath using of citric acid (citrate bath) instead of boric acid in a Watts bath", in order to cope with severe legal regulation on drainage of boron in Japan. The citrate bath has a feature in that free nickel ions are present in a sufficient amount, and about 0.1 M of nickel citrate complexes is present in the bath, and has excellent cathode current efficiency and bath pH buffering performance like the Watts bath''. Further, the citrate bath can provide fine deposits having a crystal structure nearly at random and the hardness of the deposits is about twice as large as the deposits from the Watts bath". Such characteristics may be attributable to that nickel is electrodeposited from the complexes. In this study, effect of brighteners on the deposits in the citrate bath have been studied, in comparison with those in the Watts bath, under the same plating conditions.