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Protective Atmosphere for Basic Etch Solutions

IP.com Disclosure Number: IPCOM000074499D
Original Publication Date: 1971-May-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Sybalsky, J: AUTHOR

Abstract

Basic etchants used for close tolerance etching of electronic module screening masks have a tendency to degrade in air by interaction with carbon dioxide. The interaction affects etch rate by creating variations in hydroxyl ion concentration and, to a lesser extent, in rate of formation of reaction by-products (e.g. carbonate ions). This problem, which is accentuated in systems employing large etching chambers, can be eliminated by maintaining an inert atmosphere in the chamber.

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Protective Atmosphere for Basic Etch Solutions

Basic etchants used for close tolerance etching of electronic module screening masks have a tendency to degrade in air by interaction with carbon dioxide. The interaction affects etch rate by creating variations in hydroxyl ion concentration and, to a lesser extent, in rate of formation of reaction by-products (e.g. carbonate ions). This problem, which is accentuated in systems employing large etching chambers, can be eliminated by maintaining an inert atmosphere in the chamber.

For this purpose a steady flow of inert gas (e.g. nitrogen) is maintained in the etching chamber. The gas should be admitted under pressure close to the surface of the etchant fluid in the supply pump and evacuated through outlets situated to permit the gas to completely permeate the active etching space. Input pressure should be sufficiently positive to provide a steady gas flow such that entry of air is prevented or minimized. Flow rate is tailored to chamber construction; i.e. number, extent and location of openings in the chamber.

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