Cause analysis of bright acid copper plating producing copper powder

The copper anode is a phosphorous anode. Phosphorous copper anode in the process of dissolution can easily produce small particles of bronze powder (FCu 663), because the outer current role of divalent copper ions on the cathode discharge for copper plating. Copper anodic dissolution of divalent copper ions to supplement the consumption of divalent copper ions in the bath. In addition, there are other reactions that disrupt the normal process of anodic dissolution of the results are likely to form cuprous ions such as copper anode in contact with the bath at a reversible reaction: Cu + of Cu2 + = 2Cu +. At this time, the formation of copper powders, the formation of copper particles in solution, and plated in the plating process to the board surface to form a copper slag. Insertion of a small amount of phosphorus in the smelting of copper anode process, after a period of time after the electrolytic processing, the copper anode surface to form a layer of black anodic film, its main ingredient is Cu3P. The conductivity of the anodic film does not affect the matrix can accelerate the oxidation of Cu +, and reduce the accumulation of Cu + at the same time, also to varying degrees, to prevent Cu + into the bath. Copper small crystal size of the anode surface of the anodic film will significantly reduce shedding phenomenon from the anode surface. At the same time, the anodic film, the presence of Cu2 + concentration in the solution can be maintained constant. General phosphorus content of 0.030% to 0.065% is more reasonable. Because the phosphorus content in the anode have a greater impact on some of the electrode silicon powder process. Phosphorus content is too high anodic film is too thick and solid, affect the anodic dissolution, leading to continuously reduce the copper ion content in the bath. On the contrary, the content is too small, the anodic film is difficult to prevent the copper dissolved Cu + form, copper powder in the bath increased.

Copper anode phosphorus, but the anode to produce the anode mud and small copper particles still in the process of dissolution, and this is proven in production, so we use anode bags to ensure that these substances do not enter the solution. The anode bag can not be broken or open line, and if so should be replaced.

Copper or other metal particles through various channels into the bath, such as hanging a copper powder. As the higher current density and the production line is not linked with the cleaning tank, so hang with after a certain period of time in the fastening knob parts are plated with copper plating process. General hang loose with the copper (Japan often caused by friction of the current density), easy to enter the bath after a vibration or erosion. Through the experimental point of view of the copper particles in the Hall slot, which is a major source of copper slag of the board? Add CuSO4 • 5H2O solid there will be some insoluble substances directly into the bath will cause pollution of the liquid.

Anode hanging basket and anode bars good contact is the key to guarantee the normal dissolution of copper anode, if the part of the anode basket bad electrical connections will be greatly improved anode dissolution current, not only on the anodic dissolution is very unfavorable, but also greatly increased the copper powder generated possible. 

In the bright acid copper plating process, the copper anode uses copper anode bags and anode hanging basket with 0.030% to 0.065% phosphorus. If the situations of the outside impurities, bath continuous filtration, loading maintain a certain size, good contact between the copper anode and anode bars are guaranteed, the problem of copper powder can be basically solved.Source:http://www.mhcmp.com