Solutions for discoloration in the production of copper strips

1. Control the concentration of acid solution during pickling. In the case where the surface oxide layer of the annealed copper strip is washed away, the acid concentration is too high to make any sense. On the contrary, the concentration is too high, and the residual acid adhering to the surface of the copper strip is not easily washed away, and the contamination of the washing water is accelerated, and the residual acid concentration in the washing water is too high, so that the copper strip after washing is more likely to be discolored. Therefore, when determining the concentration of the pickling solution, the concentration of the copper oxide on the surface of the copper strip should be removed as much as possible.

2. Control the conductivity of pure water. That is, the content of harmful substances such as chloride ions in pure water is controlled. Generally, it is safe to control the conductivity below 50μS/cm.

3. Control the conductivity of the hot wash water and passivation agent. The increase in the conductivity of the hot wash water and passivation agent mainly comes from the running of the copper strip to bring in the residual acid. Therefore, in the case of ensuring the quality of water used for cleaning pure water, controlling the conductivity also controls the amount of residual acid.

4. Ensure that the copper strip is dry. Partially closed at the air-ring furnace take-up exit, and a humidifier and air conditioner are used in the partial enclosure to control the humidity and temperature during the coiling of the copper strip within a certain range.

5. Passivation with passivating agent. Since benzotriazole, or BTA, is a convenient and economical passivating agent, it is now used as a passivating agent in most copper processing plants. When the copper strip passes through the BTA solution, the oxide film on the surface complexes with BTA to form a dense complex, which acts to protect the copper matrix.

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