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Multilayer Circuit Fabrication

IP.com Disclosure Number: IPCOM000074383D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bolda, FJ: AUTHOR [+2]

Abstract

This is a method for fabricating multilayer circuits in which a first circuit layer is initially formed on a solid rigid substrate, comprising the reiterative steps of: laminating a layer of insulative photosensitive film upon the first circuit layer; imaging a circuit pattern, including conductive points corresponding to points to be connected to the first circuit upon the photosensitive film and removing unexposed film; roughening the surface of the imaged photosensitive film; and forming a second circuit layer upon and conforming to the image on the photosensitive film.

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Multilayer Circuit Fabrication

This is a method for fabricating multilayer circuits in which a first circuit layer is initially formed on a solid rigid substrate, comprising the reiterative steps of: laminating a layer of insulative photosensitive film upon the first circuit layer; imaging a circuit pattern, including conductive points corresponding to points to be connected to the first circuit upon the photosensitive film and removing unexposed film; roughening the surface of the imaged photosensitive film; and

forming a second circuit layer upon and conforming to the image on the photosensitive film.

Restated, multilayer circuits are fabricated by taking an existing circuit, which is already formed on a suitable rigid substrate, and laminating a layer of solid negative photoresist film.

The photosensitive layer is exposed to a pattern and developed to form the lines and holes required for the connections between the layers. The surfaces of the film are roughened by a brush scrubber using, for example, Scotch Brite brushes. A copper film is then plated using standard SLT electroless and electroplating techniques. The copper layer is etched to a desired pattern forming the second layer. Additional layers can be added as desired.

The photosensitive film serves as a dielectric and also as a structural part. The brush scrubber treatment assists preparation of the surfaces for bonding of the electroless film.

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