Method for treating etchant
AssigneeNittetsu Mining Co., Ltd.
InventorsYasuie Mikami, Masaaki Iosaki, Masao Shibasaki
Life of this patent
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Abstract
In order to ensure an easy operation, a decreased cost in maintenance and installation, and a safe and effective use of chlorine gas generated in a closed system, a new method for treating an etchant is offered. The method comprises the following steps of; 1 treating an etchant including copper (I) chloride or ferric chloride containing copper by means of an electrolysis using a diaphragm to withdraw copper electrolytically deposited in a cathode cell, 2 supplying chlorine gas generated in an anode cell into another etchant used in an etching process, thereby enabling the etchant to be regenerated.
Claims12
A method for regenerating a waste etchant comprising obtaining a first waste etchant from an etching bath, said first waste etchant including copper (I) chloride;
- treating said first waste etchant in an electrolytic bath, having a diaphragm between a cathode and an anode, said diaphragm being electrically neutral, non-polar and having a low resistivity for enabling operation of said electrolytic bath at a minimal voltage, said treating including introducing said first waste etchant to the cathode;
- maintaining a concentration of copper ions of less than 20 g/l at said cathode;
- withdrawing copper electrolytically deposited on the cathode, thereby reducing an amount of copper in said first waste etchant;
- supplying said first waste etchant, having a reduced amount of copper, to the anode, thereby regenerating said first waste etchant by oxidizing copper ions and, thereby, generating chlorine gas;
- supplying said chlorine gas, generated in said anode, to an absorbing tower;
- introducing a second waste etchant from said etching bath to said absorbing tower, said second waste etchant including copper (I) chloride;
- regenerating said second waste etchant using said chlorine gas for regenerating said second waste etchant by oxidizing copper ions in said second waste etchant;
- and supplying said first and second regenerated etchants to said etching bath.
A method for regenerating a waste etchant comprising obtaining a first waste etchant from an etching bath, said first waste etchant including copper (I) chloride;
- treating said first waste etchant in an electrolytic bath, having a diaphragm between a cathode and an anode, said diaphragm being electrically neutral, non-polar and having a low resistivity for enabling operation of said electrolytic bath at a minimal voltage, said treating including introducing said first waste etchant to the cathode;
- maintaining a concentration of copper ions of less than 20 g/l at said cathode;
- withdrawing copper electrolytically deposited on the cathode, thereby reducing an amount of copper in said first waste etchant;
- supplying chlorine ions and copper chlorine complexes from said cathode to said anode, thereby generating chlorine gas;
- introducing said chlorine gas to an absorbing tower;
- mixing said first waste etchant, having a reduced amount of copper, and a second waste etchant, including copper (I) chloride, from said etching bath, to form a mixture;
- supplying said mixture to said absorbing tower;
- regenerating said mixture using said chlorine gas for oxidizing copper ions in said mixture;
- and supplying said regenerated mixture to said etching bath.
Dependencies are inferred from the claim text.