Regeneration of etch solutions containing trivalent manganese in acid media
AssigneeMacDermid Acumen, Inc.
InventorRoderick D. Herdman
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Abstract
A method of regenerating an etch solution comprising a metastable complex of manganese(III) ions in a strong acid is described in which at least a portion of the manganese(III) ions in the metastable complex have been destabilized, causing them to disproportionate into manganese dioxide and manganese(II) ions. The method includes the steps of i) adding an effective amount of a reducing agent to the solution; ii) allowing the reducing agent to react with the solution to cause manganese dioxide to dissolve; and (iii) applying an electrical current to regenerate manganese(III) ions in the solution.
Claims20
A method of regenerating an etch solution comprising a metastable complex of manganese(III) ions in a strong acid, wherein at least a portion of the manganese(III) ions have been destabilized, causing them to disproportionate into manganese dioxide and manganese(II) ions, the method comprising the steps of:
- a. adding an effective amount of a reducing agent for the Mn(IV) of the manganese dioxide to the etch solution;
- b. allowing the reducing agent to react with the etch solution to cause the Mn(IV) in the manganese dioxide to be reduced to Mn(II) and to dissolve;
- and
- c. applying an electrical current through an anode and a cathode in the etch solution to regenerate manganese(III) ions in the etch solution from manganese(II) ions;
- wherein the etch solution is at least substantially free of permanganate ions.
A method of regenerating an etch solution comprising a metastable complex of manganese(III) ions in at least one acid, wherein the at least one acid comprises sulfuric acid and further comprises method sulfonic acid or methane disulfonic acid, wherein at least a portion of the manganese(III) ions have been destabilized, causing them to disproportionate into manganese dioxide and manganese(II) ions, the method comprising the steps of:
- a. adding an effective amount of a reducing agent for the Mn(IV) of the manganese dioxide to the etch solution;
- b. allowing the reducing agent to react with the etch solution to cause the Mn(IV) in the manganese dioxide to be reduced to Mn(II) and to dissolve;
- and
- c. applying an electrical current through an anode and a cathode in the etch solution to regenerate manganese(III) ions in the etch solution from manganese(II) ions.
Dependencies are inferred from the claim text.