International Business Machines Corporation

Phillip A Hartley

Chi Shih Chang

Subahu Dhirubhai Desai

Robert A Martone

Keith K Ho

Robert J Haskins, Jr

Robert D Schoening

Louis J Shaffer

Debra A Gernhart

Scott A Versprille

Roy T Mulcahy

Disclosed is a design tool and a method of fabricating a multi-layer printed circuit board. The method utilizes the design tool. The knowledge base means has both (1) printed circuit board cross sectional geometric parameter to transmission line parameter data and (2) 'IF . . . THEN . . . ' production rules for lamination, registration, circuitization, testability, test tools, and test procedures. These tools relate to manufacturability, cost, test development, second level packaging and printed circuit board. The printed circuit board begins with the user entering the printed circuit board design parameters and performance parameters into the input/output interface. Next, the knowledge base production rules are applied to the printed circuit board design and performance parameters to generate a set of cross section designs meeting the user specified parameters. The printed circuit board is then built up in accordance with one of the generated cross section designs.

Method and apparatus for the cross-sectional design of multi-layer

A method of fabricating a photomask having at least three distinct zones of light transmissibility is disclosed. A first mask is made from a predetermined pattern, this mask having only two distinct zones of light transmissibility. A second mask, made by contact printing of a diazo film, is formed from a selected portion of one zone of the original pattern, which zone has the greater light transmissibility. The second mask, being a contact print, is the photographic opposite of the first. The two masks are then aligned with the selected portion of the second mask superimposed over its original location in the first mask and a composite latent image thereof is formed in a suitable emulsion. This composite image is then developed and fixed on an appropriate support to form a photomask having at least three density zones.

Photo method of making tri-level density photomask

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Vestal, NY, United States of America

Phillip A Hartley