Method of Recycling Used Copper Chloride Etch Solutions
Original Publication Date: 1988-Oct-01
Included in the Prior Art Database: 2005-Feb-15
During additive plating, copper in the form of copper sulphate has to be added. For this purpose, copper chloride is converted into copper sulphate which may be reused for additive plating. The copper chloride with added sodium chloride is converted into pure copper sulphate as follows. The excess etch solution contains copper(II)chloride, copper(I)chloride, and sodium chloride. First of all, free hydrochloric acid is neutralized by means of a 50% sodium hydroxide solution, during which process sodium chloride and water are formed. At an increased temperature, further sodium hydroxide is added, so that copper in the form of copper(II)oxide is precipitated. The water containing sodium chloride is removed and may be reintroduced for regeneration.