| 摘要 |
PURPOSE:To recover and reuse a chelating agent by adjusting a deteriorated plating soln. to a specified pH or below to deposit a chelating agent, adjusting the deposited chelating agent to a specified pH or below, and carrying out deposition and purification. CONSTITUTION:A deteriorated chemical copper plating soln. contg. Cu ions, a Cu ion chelating agent, a Cu ion reducing agent and an alkali metallic hydroxide as a pH adjusting agent is adjusted to <=4pH by adding sulfuric acid or hydrochloric acid to deposit the chelating agent, and the agent is precipitated and separated. The separated chelating agent is adjusted to <=4pH by adding sulfuric acid or hydrochloric acid to prepare a mixed aqueous soln. contg. a deposit of the chelating agent. A soln. contg. no deposit is taken selectively and continuously out of the mixed aqueous soln., and it is passed through an electrodialytic vessel and returned to the mixed aqueous soln. Thus, the chelating agent is recovered, purified, and is reused. |
