Chemistry: electrical and wave energy – Processes and products – Electrostatic field or electrical discharge
Patent
1984-04-16
1984-12-25
Andrews, R. L.
Chemistry: electrical and wave energy
Processes and products
Electrostatic field or electrical discharge
204106, 204107, 204108, C25C 112
Patent
active
044902247
ABSTRACT:
Ammoniacal solutions that have been employed in a bath for etching copper such as in the manufacture of printed circuits is reconstituted or regenerated to substantially fully remove copper solute therefrom and retain the ammonia content thereof in such a manner as to enable a continuous reuse of the etching solution. The process is conducted in such a manner that no contaminating metal powder, compounds or sludge are formed. The reconditioning is effected by introducing used ammonia solute containing ammonium etching solution into an electrolytic bath in which cathodic and anodic electrode containing compartments are defined by a cationic permeable membrane therebetween with the cathodic compartment having an electronegative cathode electrode plate therein. Normal current generation and flow in the cell is fully restricted and the copper content of the solution is substantially solely plated out as a pure metal slab on the cathode plate electrode by applying a sufficient external direct current potential to the cell, to thereby negate normal current flow of the cell, deterioration of the cathode, and prevent formation of copper powder, metal compounds and sludges within the cell from the cathode metal and the copper solute content of the ammoniacal etching solution. The operation is conducted in such a manner as to conserve the ammonia content of the used copper etch solution and enable the reconditioned solution to be reused with a minimized loss of its active etching ingredients.
REFERENCES:
patent: 2964453 (1960-12-01), Garn et al.
patent: 4028202 (1977-06-01), Ammann et al.
patent: 4280887 (1981-07-01), Konstantouros
Andrews R. L.
Lancy International, Inc.
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