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Control of Chemical Reactions

IP.com Disclosure Number: IPCOM000074951D
Original Publication Date: 1971-Jul-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

DePew, JR: AUTHOR [+2]

Abstract

Both additive and subtractive chemical reactions are carried out in a liquid environment at the surface of a conductive workpiece. Additive reactions include, for example, electroplating, electroless plating, and replacement. Subtractive processes include, for example, etching and electroerosion. Rate and termination of these various processes is controlled by an externally applied electric potential.

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Control of Chemical Reactions

Both additive and subtractive chemical reactions are carried out in a liquid environment at the surface of a conductive workpiece. Additive reactions include, for example, electroplating, electroless plating, and replacement. Subtractive processes include, for example, etching and electroerosion. Rate and termination of these various processes is controlled by an externally applied electric potential.

Electrodeposition and electroerosion are the most readily controlled situations, since electrical contact between the workpiece and an external electrode exists. In these cases, reaction rate or reaction termination is provided by control of the potential difference between the workpiece and the external electrode.

In the case of electroless plating, replacement, and etching, for example electrical contact is first provided to the workpiece, and an external electrode placed in solution with a current source connected between the workpiece and the electrode. With this arrangement, the plating, replacement, or corrosion potential between the workpiece and its chemical environment can be controlled. An increase, decrease, or cessation of the reaction can be provided by the appropriate choice of potential.

This is especially helpful in the fine control of etching. Normally, when a workpiece is removed from an etching environment, retained fluid continues the etching reaction until rinsing or neutralization are carried out. By applying curre...