International Business Machines Corporation

Warren A Alpaugh

Voya Rista Markovich

Ajit Kumar Trivedi

Michael J Canestaro

Richard Stuart Zarr

George J Macur

Carlos Juan Sambucetti

Anilkumar Chinuprasad Bhatt

Edmond Otto Fey

William J Summa

Theron L Ellis

William J Amelio

Robert Jeffrey Day

Gary Paul Vlasak

James E Sharkness

John E Larrabee

Theodore D Zucconi

A printed circuit board or card for direct chip attachment that includes at least one power core, at least one signal plane that is adjacent to the power core, and plated through holes for electrical connection is provided. In addition, a layer of dielectric material is adjacent the power core and a circuitized conductive layer is adjacent the dielectric material, followed by a layer of photosensitive dielectric material adjacent the conductive layer. Photodeveloped blind vias for subsequent connection to the power core and drilled blind vias for subsequent connection to the signal plane are provided. Also provided is process for fabricating the printed circuit board or card for direct chip attachment.

Method of making printed circuit board

Printed circuit board or card for direct chip attachment and fabrication

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

Copper is deposited onto a substrate by plating a first layer of copper onto the substrate from an electroless plating bath and plating a second layer of copper onto the first layer of copper from a second and different electroless plating bath. The first and second plating baths differ from each other in at least the cyanide content and oxygen content. The process reduces plating void defects and reduces nodule formation.

Deposition of copper from electroless plating compositions

Process for treating liquid waste compositions which contain copper ions and a complexing agent for the copper which includes reducing the concentration of copper ions in the waste solution to less than about 8 ppm and contacting the solution with an ozone-containing gas and irradiating with ultraviolet light.

Treatment of waste compositions

A cleaning process for high aspect ratio through holes of multilayer printed circuit boards assures the removal of any loosened fiberous material or epoxy smears in the through holes and also provides an inverted 'T' structure at the innerplanes of the internal conductive circuits within the printed circuit board sandwich. The inverted 'T' structure helps to move the contact point between the plating of the through hole and the internal circuit lines further into the circuit board, thereby eliminating the 'Z' stress at the edge of the innerplane. This process is accomplished by first vapor blasting the through holes, soaking the board in a suitable solvent to loosen any fibers or smears on the circuit innerplanes of the board, removing the excess solvent from the through holes and then feeding a unilateral stream of a cleaning solution through the holes, the cleaning solution operating to remove excess fibers and smears in the through holes and to produce a slight, uniform etchback of the metal innerplanes of the printed circuit boards. Thereafter, the solution may be reduced and any excess cleaning solution is removed.

Cleaning of high aspect ratio through holes in multilayer printed

Copper is electrolessly deposited on a surface wherein the dissolved oxygen content is maintained between 2 and 4 ppm in the plating bath.

Electroless copper plating process with dissolved oxygen maintained in

A three step seeding process with a hot water rinse and bake includes first contacting the surface of a substrate with a stannous chloride sensitizing solution, followed by a hot water rinse to remove any excess stannous chloride. Next, a palladium chloride activator is used to interact with the stannous compounds to form an adherent layer of metallic palladium particles. Thereafter, the surface is subjected to a palladium chloride/stannous chloride/HCL seeder bath which deposits a final catalytic layer on the surface and drilled through holes to facilitate the electroless plating of a metal of the substrate. A subsequent baking at a temperature between 105.degree. C and 120.degree. C sets the seeder on the substrate surface and in the through holes in the substrate.

Method for preparing substrate surfaces for electroless deposition

A method for producing a resin rich epoxy-glass prepreg and laminate wherein the epoxy-glass prepreg is given a first pass through an impregnation tower and impregnated with dicyandiamide cured brominated bisphenol type epoxy modified with a polyfunctional additive and advanced to 80-85% of complete cure. The prepreg is given a second pass through the tower and given a dip coating of, for example, brominated bisphenol A which is advanced to 80-85% of complete cure. The resulting prepreg serves as the outer sheet of a multi-layer printed circuit board and it has a resin rich surface necessary for chemical roughening and subsequent additive plating.

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Chenango Forks, NY, United States of America

Warren A Alpaugh