Requirements of bright acid copper plating on the anode
Copper ions in acidic copper plating solution mainly depends on the normal dissolved anode to supplement. In general, electroplating, in order to prevent impurities from entering the bath caused by failure, often using high purity metal as the anode. In acidic copper plating system, if the use of copper as the anode, anode mud will produce a lot of, in the gas stirring or moving cathode case, sludge and easy to fall and the pollution of plating solution, so the anode while in high purity copper, but serious, easy to cause the coating surface roughness, and even make the coating is not bright, effect of the coating quality. Time study prove: the incorporation of a small amount of phosphorus in copper anode, composed of phosphorized copper anode but this phenomenon to a large extent inhibited. The amount of phosphorus in the anode with 0.1 ~ 0.6%. Phosphorus requirements of the uniform, the best use of steel casting, copper anodes after molding can by pressing and forging is more ideal.
The first use of the anode surface should be clean, and placed in dilute sulfuric acid solution soak 2 to 3 hours (to prevent floating copper ions into solution). The anode is hung in the plating bath, should keep Yin, anode area ratio of 1 ∶ 2 ~ 3, the anodic current density is not too high. Anode normal dissolved, black mold surface shall have a layer of loose black film or thick, if erase the black film, anode with ice like crystal pattern.
In addition, but also consider the effects of sulfuric acid concentration on anodic dissolution, when high temperature is low or sulfuric acid content in solution, copper sulfate concentration is close to saturation, the edge and the lower end of the anode can be observed in the blue copper sulfate crystallization, it will stop the current through, easy to cause the anode passivation.
Detection of electroplating anode
Electroplating anode is to provide conductive function and provide important materials for the main salt metal ion plating process, the insoluble anode situation certainly is useful only conductive effect and does not provide the metal ion, but most still using soluble anode. Detection of electroplating anode mainly refers to the detection of soluble anode.
The soluble anode, test project is the main composition and the content of metal purity and impurity. For the majority of soluble anode, purity process in accordance with the requirements of 99.99%, four and 9 level that is often said that. But the anode materials used in actual production, often can not reach this level, only three of 9 or lower level. This means that the impurity content in the anode is higher, this is a hidden danger for the electroplating quality. Long term use of anode high impurity content, metal impurity ions into solution in the cathode and coating deposition, become the unfavorable factors influencing the coating quality, and also to remove difficulties.
Therefore, testing for anode purity, generally need to physical method for trace analysis such as spectroscopy, electron probe method for the accurate analysis, it is difficult to achieve in the electroplating enterprises, need to entrust a professional institution for determination. |
