Digital Equipment Corporation

Arshad Ahmad

James C Lee

Francisca Tung

Myrna E Castro

Chune Lee

A method of forming a multilayer circuit board is disclosed which includes a build-up process in which, beginning with a solidified layer of the dielectric disposed upon a substrate, alternate layers of conducting metal and dielectric are sequentially deposited. Each layer of conducting metal lines is defined using photoresist and a photolithographic technique. After the lines are deposited, the photoresist is removed and a second layer of photoresist defines the conductive posts which function as through holes between metal layers. After each layer of conductive line and posts is formed, and the photoresist is removed, the dielectric is flowed into place and solidified to insulate adjacent metal lines and posts. The process may be repeated as many times as necessary to build up layers of conducting metal and dielectric, and form the completed multilayer wiring board.

Sequential multilayer process for using fluorinated hydrocarbons as a

A very fine line three-dimensional package is constructed without lamination during construction of the signal core. Construction of the signal core employs a method of line and hole formation and planarization without drilling, and avoids imposing excessive stress on the package during its assembly. In forming the three-dimensional structure, a power core which may comprise a single or multiple layers is manufactured in the conventional method using a very high dielectric constant material. A signal core is on both sides of the power core, using a sequential approach with a low dielectric constant material. The method comprises utilizing photoresist techniques to define the regions of horizontal lines running parallel to the surface of the power core substrate and vertical posts running perpendicular to the surface of the power core, as each layer of lines and posts is established. After metallization of the lines and posts, the dielectric is flowed over the pattern of lines and posts to form a finished layer of the signal core. The sequence is repeated as many times as necessary to build up the required wiring pattern in the signal core. Layers of signal core are built up sequentially on both sides of the power core by alternating between depositing conducting metal and flowing and solidifying a dielectric in place.

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San Jose, CA, United States of America

Arshad Ahmad