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Subtractive Etch Promoting Dummy Lines

IP.com Disclosure Number: IPCOM000035985D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Fink, P: AUTHOR [+6]

Abstract

Segments of dummy signal lines are added to a signal plane in areas of low wiring density to obtain a uniform subtractive etch rate across the entire printed circuit with low and high density copper areas.

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Subtractive Etch Promoting Dummy Lines

Segments of dummy signal lines are added to a signal plane in areas of low wiring density to obtain a uniform subtractive etch rate across the entire printed circuit with low and high density copper areas.

Dense signal wiring areas on signal planes have a lower etch rate than unpopulated areas. A signal line in unpopulated areas is easily overetched, since the etch solution is capable of penetrating the few signal lines unimpeded, causing them to be overetched to an extent that opens occur.

To overcome these disadvantages, the dummy line segments are arranged in such a manner that they do not influence the signal line characteristics nor the yield through shorts in the actual signal lines. The dummy signal lines afford a uniform etch rate in all areas of a signal plane, thus improving the product yield and electrical characteristics. The signal line width distribution is narrower owing to the smaller signal line width tolerance of a signal plane. A dynamic dummy signal line segment installed in the automatic wiring program can be automatically placed at defined grid points in areas of low density.

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