Phosphor copper anode eliminates or reduces the formation of copper powder

Phosphorous copper anode must be used for acid bright copper plating. Because the phosphorus free copper anode in the bath dissolution rate is fast, the anode current efficiency is high, resulting in the accumulation of copper ions in the bath, and because the anode dissolution rate is fast, resulting in more copper powder into the solution, resulting in the formation of more copper powder floating in the liquid, so that the coating becomes rough, producing nodules, at the same time, the anode mud is also increased.

If the fire copper containing impurities is used as the anode, the copper in the anode dissolution is almost no copper powder, in fact, there is no anode mud, the anode is formed on a layer of fairly firm binding black colloidal film. Extensive research by the American Brass Company has shown that if more than 0.005% of phosphorus or arsenic is added to pure copper, electrolysis will produce a black-brown to black film on the anode surface, and the formation of copper powder can be inhibited. In 1981, Bulgaria et al. 191 determined the composition of the black film and found that the black film was mainly Cu3P and had metal conductivity. This explains why the black film does not dull the anode. They suggest that the phosphorus is involved in the formation of univalent copper at the dissolution of the phosphorus-containing copper anode, preventing disproportionation.

The use of high quality phosphorus containing copper anode, in the plating process can form a layer of black protective film on the anode surface, it is like a fence, can control the dissolution rate of copper, the anode current efficiency is close to the cathode current efficiency, copper ions in the plating solution to maintain balance, and greatly reduce the anode mud. The phosphorus content in the anode should be kept appropriate. If the phosphorus content is too low, the anode black film is too thin to play a protective role. Too much phosphorus content and too thick anode black film lead to anode shielding passivation, affect the anode dissolution, so that the copper ion in silver solution is reduced. Whether the flow content is too low or too high, it will increase the consumption of additives, affect the quality of copper plating and the great fluctuation of the concentration of copper ions in the plating solution, which needs to be adjusted frequently, increasing the difficulty of process stability control.