シアン化銅メッキのメッキ条件, および添加剤の陽極分極に及ぼす影響

Abstract

There are only a few reports on the anode behavior in copper cyanide plating baths, since the anode behaviors seem to have no effect on the cathode deposits directly, and anode passive films to have little reproductivity.The author determined the anode polarization in copper cyanide plating baths under various electrolytic conditions, changing bath compositions and additives.The results obtained were summarized as follows:1) Comparing K+ bath with Na+ bath, the anode polarization in the K+ bath was less than in the Na+ bath within lower current density range than that required to make the anode passive, which, however, was lower in the K+ bath than in the Na+ bath.2) With low concentration of copper and free cyanide, the anode passive occurred at low current density.3) With increasing carbonate concentration, the current density required to make the anode passive decreased and the anode polarization increased. The same phenomena were observed at very low concentration of carbonate, but this was not obvious in the Na+ bath.4) The current density required to make the anode passive became high by agitating the bath, elevating the bath temperature, using PR (periodic reverse) current and the like.5) Many additives produced little effect on the anode behavior.6) The difference in material of the anode had little effect on the anode polarization. But the anode obtained by electroforming from the sulfate bath with thiourea, was harder to be made passive than the others.7) The color of the anode passive film was reddish brown within low current density, it changed to blackish brown or black at the current density high enough to produce oxygen bubbles, and at higher current density, it turned bluish white. This may indicate that the films consisted of cuprous oxide at the first, cupric oxide at the second, and insoluble carbonate or cyanide at the last stage.