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Browse Prior Art Database

Etch-Stop Indicator for Chemically Milled Parts

IP.com Disclosure Number: IPCOM000036732D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Erpelding, AD: AUTHOR

Abstract

Disclosed is a feature that simplifies the inspection of chemically milled parts for dimensional accuracy. The feature is part of the artwork that, when strategically located, is used to accept or reject large panels of etched parts. It is used as a go, no-go criteria rather than measuring components with time-consuming optical techniques.

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Etch-Stop Indicator for Chemically Milled Parts

Disclosed is a feature that simplifies the inspection of chemically milled parts for dimensional accuracy. The feature is part of the artwork that, when strategically located, is used to accept or reject large panels of etched parts. It is used as a go, no-go criteria rather than measuring components with time- consuming optical techniques.

The disclosed feature resembles opposing fingers that overlap (see figure). The amount of overlap is the etch factor which compensates for the undercutting of the etch process. Typically,the etch factor is a percentage of the part thickness. The parts are etched to their correct dimensions when the ends of the overlapping "etch fingers" are in line.

This concept assumes first that the mask is correct. This would be verified with check prints of the mask. The second assumption is that the etch process is uniform across the panel of etched parts. Uniformity can be checked with an array of these "etch fingers" in a panel.

It is intended that the "etch fingers" be located only in a few representative areas of a panel, for example, two diagonal corners and center. The "etch fingers" at these locations would be the only criteria the etch process would be required to meet and by which parts would be judged good or bad.

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