Rosenberg, Klein & Lee
Method for treating spent tin/lead stripping solution
The present invention relates to a method for treating spent tin or tin/lead stripping solution used in the electronic industry, particularly in the manufacture of printed circuit boards or a lead frames. Said method comprises (i) electrolytically reducing copper ions in the solution to copper at a low temperature; (ii) electrolytically oxidizing Sn2+ and Pb2+ in the solution at a high temperature to form solid tin and lead oxides and hydroxides; (iii) separating solid tin and lead oxides and hydroxides from the solution; (iv) dissolving tin and lead oxides and hydroxides obtained in step (iii) in a strong alkali or acidic solution; and (v) electrolytically reducing the alkali or acidic solution obtained in step (iv) at a high temperature to recover metallic tin and lead. Also, the filtrate obtained in step (iii) above is useful for preparing fresh tin or tin/lead stripping solution.
Persee Chemical Co., Ltd. Amia Co., Ltd.
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Tai-Sheng Yu-Feng Huei-Yin Kuo-Chin Jenn-Fang Ching-Hwa Hung-Ming
Yuan Lin Cheng Chen Wu Chang Wang