Browse Prior Art Database

Process Monitor for Ferric Chloride Etchant

IP.com Disclosure Number: IPCOM000061994D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Fey, EO: AUTHOR

Abstract

Ferric chloride solutions are used to etch stainless steel for a variety of applications, e.g., the fabrication of print bands. Knowledge of and control of the concentration of the active etching species in the bath, ferric ion, is necessary to achieve uniform results. The following describes a method of measuring and controlling the composition of ferric chloride etchants.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 67% of the total text.

Page 1 of 1

Process Monitor for Ferric Chloride Etchant

Ferric chloride solutions are used to etch stainless steel for a variety of applications, e.g., the fabrication of print bands. Knowledge of and control of the concentration of the active etching species in the bath, ferric ion, is necessary to achieve uniform results. The following describes a method of measuring and controlling the composition of ferric chloride etchants.

The current for the reduction of ferric ions, measured at a rotating platinum electrode at some potential in the broad limiting current plateau region, has been observed to decrease in a linear fashion as the number of parts processed by the etchant increases. This decrease in current is caused by the consumption of ferric ions during etching.

Relatively low electrode rotation speeds are preferred, since under these conditions the limiting current region is reached at lower applied potentials and is broad.

Automatic control of the ferric concentration may be established using the current measured at the rotating disk to control the addition of ferric chloride to the etching solution.

By moving to anodic potentials a similar limiting current plateau for the oxidation of ferrous ions is observed. As for the ferric concentration, the current measured at any potential in this plateau region is proportional to the concentration of ferrous ion. In a fresh etching bath the ferrous concentration is very low, but increases as etching progresses.

Knowledge of...