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Method of Continuously Recovering Cupriferous Persulphate Solutions for The Surface Treatment of Copper Layers

IP.com Disclosure Number: IPCOM000120513D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 44K

Publishing Venue

IBM

Related People

Braitmayer, R: AUTHOR [+3]

Abstract

For the surface treatment (etching) of copper layers, acid persulphate solutions are used. Etching is carried out according to the equation Cu + S2O82- ---> CuSO4 + SO42- . The etch rate declines as the amount of copper in the etch bath increases and the amount of persulphate decreases, so that the bath becomes unserviceable.

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Method of Continuously Recovering Cupriferous Persulphate Solutions
for The Surface Treatment of Copper Layers

      For the surface treatment (etching) of copper layers,
acid persulphate solutions are used.  Etching is carried out
according to the equation
   Cu + S2O82-  --->  CuSO4 + SO42- .
The etch rate declines as the amount of copper in the etch bath
increases and the amount of persulphate decreases, so that the bath
becomes unserviceable.

      The described method serves to continuously remove copper ions
by electrolysis, decomposing a minimum amount of persulphate.  This
permits etching at constantly low copper concentrations.  The
persulphate used during etching has to be replenished.  The
disadvantage of existing methods is that the cathodic reduction of
persulphate increases as the copper concentration decreases.

      By a special electrolytic method comprising the following
features, copper is cathodically deposited without decomposing
persulphate:
      -    a cell structure with a flow cell;
      -    an electrode arrangement with a cylindrical outer
           anode and a cylindrical inner cathode;
           electrode material - anode: titanium, cathode:
           titantium, later copper;
           anode/cathode space divided by fabric rather than
           a diaphragm; current density: cathode: about 1.6
           A/dm2 (anode:  less)

      Labora...