International Business Machines Corporation

Gary Lee Schild

Donald Seton Farquhar

Ross William Keesler

Michael Joseph Klodowski

Andrew Michael Seman

James Russell Bupp

Bernd Karl-Heinz Appelt

A method of forming a plurality of solid conductive bumps for interconnecting two conductive layers of a circuit board with substantially coplanar upper surfaces. The method comprises the steps of applying a continuous homogenous metal layer onto a dielectric substrate, applying a first photoresist and exposing and developing said first photoresist to define a pattern of conductive bumps, etching the metal layer exposed by said development to form said plurality of conductive bumps, removing said first photoresist, applying a second photoresist onto the metal layer, exposing and developing said second photoresist to define a pattern of conductive bumps and circuit lines; etching the metal layer exposed by said development to form a pattern of circuit lines in said metal layer; and removing said second photoresist. The methods of the present invention also provides for fabricating a multilayer circuit board and a metallic border for providing rigidity to a panel.

Manufacturing methods for printed circuit boards

A method of forming a plurality of solid conductive bumps for interconnecting two conductive layers of a circuit board with substantially coplanar upper surfaces. The method comprises the steps of applying a continuous homogenous metal layer onto a dielectric substrate, applying a first photoresist and exposing and developing said first photoresist to define a pattern of conductive bumps; etching the metal layer exposed by said development to form said plurality of conductive bumps; removing said first photoresist; applying a second photoresist onto the metal layer; exposing and developing said second photoresist to define a pattern of conductive bumps and circuit lines; etching the metal layer exposed by said development to form a pattern of circuit lines in said metal layer; and removing said second photoresist. The methods of the present invention also provides for fabricating a multilayer circuit board and a metallic border for providing rigidity to a panel.

A method of forming a printed circuit board comprising a plurality of conductive bumps with substantially coplanar upper surfaces. The method comprises the steps of applying a metal layer onto a dielectric substrate; applying a first photoresist onto said substrate and exposing and developing said first photoresist to define a pattern of conductive bumps; etching the metal layer exposed by said development to form said plurality of conductive bumps; removing said first photoresist; applying a second photoresist onto the metal layer; exposing and developing said second photoresist to define a pattern of conductive bumps and circuit lines; etching the metal layer exposed by said development to form a pattern of circuit lines in said metal layer; and removing said second photoresist. The present invention is also provides a method for preparing a reinforced panel.

A printed circuit board comprising a plurality of conductive bumps having substantially coplanar upper surfaces is provided. The circuit board is formed by providing: a substantially planar metallic layer having a first thickness on at least one surface of the dielectric; applying a first photoresist on the metal layer; imaging the first photoresist to define a pattern of conductive bumps; etching the exposed portions of the metal layer to a second thickness to form the conductive bumps; removing the first photoresist; applying a second photoresist to the metal layer; imaging the second photoresist to define a pattern of circuitry; etching the exposed portions of the metal layer to provide the electrical circuitry; and removing the second photoresist. The present invention also provides a method for preparing printed circuit boards wherein two conductive layers that are disposed on opposing sides of a dielectric layer are inter-connected by at least one of the substantially coplanar conductive bumps. The method comprises the additional steps of depositing a second dielectric layer on the substantially coplanar conductive bumps and circuitry; exposing the upper surface of at least one of the conductive bumps; and depositing a second metal layer on the second dielectric layer and the exposed upper surface of the conductive bump. The present invention is also related to a method for preparing a reinforced panel. The method comprises the steps of: applying a metal layer having a first height on at least one surface of a dielectric substrate; applying a first photoresist to the metal layer, imaging the photoresist to provide at least one section of remaining photoresist defining an opening therein and at least one exposed region of the metal layer; etching the exposed region of the metal layer to a second height; and removing the remaining photoresist to provide a multi-layered structure comprising a dielectric layer and a metal layer comprising at least one region having a second height and at least one region having a first height.

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Endicott, NY, United States of America

Gary Lee Schild