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A Technique for Continuous Control of Cu+ Concentration in Copper Etching Baths

IP.com Disclosure Number: IPCOM000060639D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bindra, P: AUTHOR [+3]

Abstract

The Cu+ product of the etching of copper from boards and cards by cupric chloride is converted back to Cu2+ by a process of bubbling water-saturated air or oxygen into the etch bath. The bubbling rate of the water-saturated air or oxygen is controlled so that the Cu+ concentration can be kept low, and wide fluctuations in the etch rate and thus inefficient etching are completely avoided. This process eliminates the need for the purchas storing, and adding of oxidizing chemicals such as hydrogen peroxide H2O2 to the etch bath so as to convert Cu+ to Cu2+ . Bath dilution is also prevented, avoiding the need to dispose of etchant on a periodic basis.

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A Technique for Continuous Control of Cu+ Concentration in Copper Etching Baths

The Cu+ product of the etching of copper from boards and cards by cupric chloride is converted back to Cu2+ by a process of bubbling water-saturated air or oxygen into the etch bath. The bubbling rate of the water-saturated air or oxygen is controlled so that the Cu+ concentration can be kept low, and wide fluctuations in the etch rate and thus inefficient etching are completely avoided. This process eliminates the need for the purchas storing, and adding of oxidizing chemicals such as hydrogen peroxide H2O2 to the etch bath so as to convert Cu+ to Cu2+ . Bath dilution is also prevented, avoiding the need to dispose of etchant on a periodic basis.

Continuous measurement of Cu+ concentration can allow control of the bubbling rate and, hence, the rate of oxidation of Cu+ to Cu2+ . This allows one to maintain the Cu+ concentration at the optimal value. Techniques for in-situ measurement of Cu+ concentration are known.

By the process of bubbling water saturated air or oxygen into the etch bath, Cu+ is rapidly oxidized to Cu2+ . This rapid removal of Cu+ eliminates the previously known, undesirable buildup of Cu+ in the etching solution.

Disclosed anonymously.

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