CONTROL METHOD FOR ETCHING SOLUTION

摘要

PURPOSE:To suppress the generation of gaseous chlorine, to reduce the amt. of the liquid chemical to be used and the amt. of waste soln. and to improve quality as a result of stable control by regenerating a CuCl2 etching soln. by electric diaphragm dialysis and adjusting the above-mentioned soln. by electrode potential in synchronization with the control of the specific gravity and hydrochloric acid concn. of the above- mentioned soln. CONSTITUTION:The above-mentioned soln. 3 used for etching is fed to the anode 7 side of a regenerating vessel 6 bisected by an anion premeable membrane 9 to the anode 7 side and cathode 8 side. The hydrochloric acid 5 soln. on the cathode 8 side is so controlled as to attain a prescribed concn. and the above-mentioned soln. 3 on the anode 7 side is circulated and supplied while the conc. and the specific gravity of the hydrochloric acid 5 are adjusted. Electric current is passed between both electrodes 7 and 8. The univalent copper ions in the above-mentioned soln. 3 are oxi dized to bivalent ions in the anode 7 part and the chlorine ions are migrated form the hydrochloric acid 5 soln. on the cathode 8 side to the anode 7 side. The potential difference between the anode 7 and the soln. 3 is measured and the regeneration of the above-mentioned soln. 3 in the vessel 6 is controlled in accordance with the change in the electric resistance value thereof.