Electrolytic regeneration of spent etchant - contg. iron and copper chloride(s), esp. from printed circuit boards mfr. to avoid pollution and increase etching power

摘要

Spent etching solns. contg. chloride ions are regenerated by electrochemical oxidn., in which copper is deposited at the cathode, and chlorine is evolved at the anode; and the Cl2 is used for regenerating the soln. pref. the soln. is fed in counter current to the evolved Cl2 and to the anode at min. 1.5 times the linear speed at which the soln. is fed to the cathode; and the spent soln. pref. contains (a) CuCl2; or (b) FeCl2 and CuCl2. Specific spent soln. contains 0.7-1.4 mole/l FeCl3, 0.9-1.5 mole/l CuCl2, 1.1-2.0 mole/l alkali metal chloride, 0.2-0.8 mole/l HCl, with water to 1l. Electrolysis of soln. (a) is pref. at 15-80, esp. 25-40 A/dm2; and at 8-35, esp. 15-20 A/dm2 for solns. (b); in all cases, regeneration is pref. at 10-40 degrees C.