ETCHING PROCESS
Etching copper metal from printed circuit boards:
Cuo+ Cu(NH3)4Cl2=> 2 Cu(NH3)2Cl (dissolution)
2 Cu(NH3)2Cl + ½ 02 + 2 NH3 + 2 NH4Cl => 2 Cu(NH3)4Cl2 + H2O (oxidation)
These two equations can be summarized in one equation:
Cuo + 2 NH3 + 2 NH4Cl + ½ O2 => Cu(NH3)4Cl2 + H2O
SOLVENT EXTRACTION AND ELECTROWINNING PROCESS
Extracting copper from spent etchant or spent rinse water:
Cu(NH3)4Cl2 + 2 RH(org) => CuR2(org) + 2 NH3 + 2 NH4Cl
Stripping copper from the organic solution to the electrolyte:
CuR2(org) + H2SO4 => CuSO4 + 2 RH(org)
Electrowinning copper metal from the electrolyte:
CuSO4 + H2O => Cuo + H2SO4 + ½ O2