The anode used for acid bright copper plating must be a phosphorous-containing copper anode. This is because the pure copper anode is easily dissolved, making the anode efficiency greater than the theoretical value. As a result, the copper content in the bath gradually increased, causing a large amount of copper sulfate to accumulate, quickly exceeding the upper limit of the process specification and losing balance. On the other hand, the pure copper anode will produce a small amount of monovalent copper ions when it is dissolved. It is very unstable in the plating solution and decomposes into bivalent copper ions and particulate metal copper through a disproportionation reaction. It is easily formed on the plating layer during the plating process. glitch. In order to eliminate the impact of anodic copper, people first used anode bags, but soon discovered that too much sludge prevented the circulation of the bath. Later, the use of oxygen-free high-conductivity copper anodes (0FHC), although the slime reduction, but still can not prevent the formation of copper metal particles, so the use of hydrogen peroxide in the bath is periodically added to the oxidation of monovalent copper to divalent copper, However, this method consumes part of the sulfuric acid in the chemical reaction, resulting in a drop in the concentration of sulfuric acid in the bath, which must be promptly replenished. At the same time, it must be supplemented by brighteners that are depleted by the hydrogen peroxide oxidation and increase the cost of electroplating.
In 1954, the American Nevers et al. added a small amount of phosphorus to the anode for pure copper and found that the surface of the anode layer formed a black colloidal film. During the electroplating, the anode dissolves almost no copper powder, and there is very little sludge. The copper coating on the surface of the part is not There will be glitches. This is due to the fact that the black film of the phosphorus-containing copper anode has conductive properties, its pores do not affect the free passage of copper ions, accelerate the oxidation of monovalent copper, prevent the accumulation of monovalent copper, and greatly reduce the monovalent copper in the bath. Ion; At the same time, the dissolution of the anode and the cathode deposition efficiency are gradually approached, and the balance of copper content in the copper plating solution is maintained. The experience of the Ford Motor Company in using this phosphorous-containing copper anode proves that it not only guarantees the quality of the copper plating layer, but also saves 20% of electroplating brightener and reduces the cost.
Bulgarian scholar Rashkov et al. studied the black film on the anode surface. The main component is Cu3P, and it has metallic conductivity. This explains why the black film does not passivate the anode. They believe that the role of phosphorus lies in the formation of Cu3P from monovalent copper produced when the phosphorous-anode is dissolved, thus preventing the generation of disproportionation reactions. The U.S. federal regulation QQ-A-6738 suggests that copper-containing copper anodes have a mass fraction of 99.9%-99.94% and a phosphorus content of 0.04%-0.065%. There are also phosphorous copper plates in China that contain phosphorus in the range of 0.1% to 0.3%.
If the mass fraction of phosphorus in the phosphor bronze anode is high, it may cause the phosphorus-containing copper anode not to dissolve easily, so that the content of copper in the plating solution is decreased, and the luminance in the low current density area is poor. In severe cases, the black film on the anode falls off from the anode, contaminates the bath, and it also blocks the anode bag, causing the cell voltage to rise and the coating to produce fine sand. Therefore, controlling the phosphorous-containing copper anode is very important for the bright copper plating process of sulfuric acid.
In 1954, the American Nevers et al. added a small amount of phosphorus to the anode for pure copper and found that the surface of the anode layer formed a black colloidal film. During the electroplating, the anode dissolves almost no copper powder, and there is very little sludge. The copper coating on the surface of the part is not There will be glitches. This is due to the fact that the black film of the phosphorus-containing copper anode has conductive properties, its pores do not affect the free passage of copper ions, accelerate the oxidation of monovalent copper, prevent the accumulation of monovalent copper, and greatly reduce the monovalent copper in the bath. Ion; At the same time, the dissolution of the anode and the cathode deposition efficiency are gradually approached, and the balance of copper content in the copper plating solution is maintained. The experience of the Ford Motor Company in using this phosphorous-containing copper anode proves that it not only guarantees the quality of the copper plating layer, but also saves 20% of electroplating brightener and reduces the cost.
Bulgarian scholar Rashkov et al. studied the black film on the anode surface. The main component is Cu3P, and it has metallic conductivity. This explains why the black film does not passivate the anode. They believe that the role of phosphorus lies in the formation of Cu3P from monovalent copper produced when the phosphorous-anode is dissolved, thus preventing the generation of disproportionation reactions. The U.S. federal regulation QQ-A-6738 suggests that copper-containing copper anodes have a mass fraction of 99.9%-99.94% and a phosphorus content of 0.04%-0.065%. There are also phosphorous copper plates in China that contain phosphorus in the range of 0.1% to 0.3%.
If the mass fraction of phosphorus in the phosphor bronze anode is high, it may cause the phosphorus-containing copper anode not to dissolve easily, so that the content of copper in the plating solution is decreased, and the luminance in the low current density area is poor. In severe cases, the black film on the anode falls off from the anode, contaminates the bath, and it also blocks the anode bag, causing the cell voltage to rise and the coating to produce fine sand. Therefore, controlling the phosphorous-containing copper anode is very important for the bright copper plating process of sulfuric acid.