International Business Machines Corporation

Robert Jeffrey Day

Edmond Otto Fey

Voya Rista Markovich

Anilkumar Chinuprasad Bhatt

Thomas R Miller

Ashwinkumar C Bhatt

Christina Marie Boyko

Jeffrey Alan Knight

Thomas P Duffy

Kristen Ann Stauffer

Edward Lee Arrington

Richard William Malek

John Christopher Camp

Curtis Michael Gunther

Michael J Canestaro

Warren A Alpaugh

Anikumar Chinuprasad Bhatt

John E Larrabee

The present invention teaches a simplified process for fabricating high density printed wiring boards using a semi-additive process. Steps required to achieve this objective include adhering an electroless plated copper commoning layer to a surface roughened dielectric substrate. Subsequently, the commoning layer is photolithographically personalized by covering the commoning layer with a resist and then uncovering predetermined areas of the aforementioned commoning layer. Consequently, the semi-additive method involves electroplating copper onto the uncovered areas of the commoning layer, thereby generating copper features and circuitry. Finally, the semi-additive process requires the stripping of the remaining photoresist, and the unplated electroless copper layer is etched in order to electronically isolate the copper features and circuitry lines.

Process for manufacturing a printed wiring board

A process for removal of undesirable conductive material (e.g., catalyst material and seeped circuit material) on a circuitized substrate and the resultant circuitized substrates disclosed. Such process and resultant circuit effectively address the electrical shorting problems caused by nonremoval of the residual catalyst material and circuit material which has seeped under the residual catalyst material. The process includes the steps of: a) providing a catalyst layer (e.g., palladium and tin) having circuit pattern (e.g., copper) thereon; b) pretreating the catalyst layer and the circuit pattern (e.g., with a cyanide dip) for removal of undesirable portions of each which cause electrical leakage between circuit lines of the circuit pattern; c) oxidizing the catalyst layer and the circuit pattern (e.g., with chlorite, permanganate, hydrogen peroxide, or air at a temperature elevated above ambient conditions); and d) removing the undesirable portions of the catalyst layer and the undesirable portions of the circuit pattern (e.g., with a cyanide submersion). The resultant circuitized substrate includes a circuit pattern on a catalyst layer wherein undesirable portions of the catalyst layer and circuit pattern are completely removed between the circuit features of the circuit pattern so that electrical leakage between the circuit features does not occur.

Process for removal of undesirable conductive material on a circuitized substrate and resultant circuitized substrate

The present invention teaches a simplified process for fabricating high density printed wiring boards using a semi-additive process. A roughened copper foil is laminated to a dielectric substrate. The foil is subsequently removed from the dielectric to create a roughened, irregular surface on the dielectric substrate. Vertical angle through holes and blind holes are formed in the substrate. A uniform copper commoning layer is electrolessly plated to the roughened dielectric substrate and through holes. A photoresist is applied on the surface of the electroless plated layer and irradiated through a mask having printed circuit features. After developing the photoresist the uncovered electroless layer is electrolytically plated to create the final features and circuitry. After stripping the remaining photoresist the unplated electroless copper layer is etched to electronically isolate the copper features and circuitry lines.

Process for removal of undersirable conductive material on a circuitized

A process for making a circuitized substrate is defined wherein the substrate is treated with two different, e.g., additive and subtractive, metallization processes. The process is thus able to effectively produce substrates including conductive features, e. g., high density circuit lines and chip heat-sinking pads, of two different degrees of resolution in a cost effective and expeditious manner. The resulting product is also defined.

Circuitized substrate with same surface conductors of different

A process for making a circuitized substrate is defined wherein the substrate is treated with two different, e.g., additive and subtractive, metallization processes. The process is thus able to effectively produce substrates including conductive features, e.g., high density circuit lines and chip heat-sinking pads, of two different degrees of resolution in a cost effective and expeditious manner. The resulting product is also defined.

Method of making a circuitized substrate using two different

Disclosed is a method of drilling, desmearing, and additively circuitizing a printed circuit board. The printed circuit board is drilled under conditions which produce glass and polymer smeared vias and through holes. The particulate debris is removed by vapor blasting the drilled printed circuit board. Next the printed circuit board is soaked in a solvent to swell the drill smear on the circuit interplanes of the printed circuit board. This solvent is then removed by entrainment in a gas, and a stream of an aqueous, acidic, oxidizing solution is passed through the printed circuit board holes to remove swollen smear in the thru holes and produce an etchback of conductors. After a water rinse an aqueous reducing solution is passed through the printed circuit board to reduce and remove aqueous acidic oxidizing solution, e.g., residual aqueous acid oxidizing solution. The printed circuit board is rinsed to remove the aqueous reducing solution. The surface of the printed circuit board is then seeded, the intended circuitization is photolithographically defined on the printed circuit board, and the circuitization, including the surface circuitization and the plated through hole circuitization, is additively plated.

Methyl chloroform-free desmear process in additive circuitization

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Dryden, NY, United States of America

Robert Jeffrey Day