International Business Machines Corporation

Heike Marcello

David John Russell

Gerald Walter Jones

Gary A Johansson

Elizabeth F Foster

John M Lauffer

Kostas I Papathomas

Jeffrey McKeveny

Anastasios Peter Angelopoulos

Richard William Malek

Voya Rista Markovich

A method for fabricating circuitized substrates which reduces shorts, and does not require baking and resulting film. The method employs a photoimageable dielectric film, having a solvent content less than about 5%, and a glass transition temperature, when cured, which is greater than about 110&deg; C. A photoimageable dielectric film is provided having from about 95% to about 100% solids, and comprising: from 0% to about 30% of the solids, of a particulate rheology modifier; from about 70% to about 100% of the solids of an epoxy resin system (liquid at 20&deg; C.) comprising: from about 85% to about 99.9% epoxy resins; and from about 0.1 to 15 parts of the total resin weight, a cationic photoinitiator; from 0% to about 5% solvent; applying the photoimageable dielectric film to a circuitized substrate; and exposing the film to actinic radiation.

Photoimageable dielectric epoxy resin system film

A method for fabricating circuitized substrates which reduces shorts, and does not require baking and resulting film. The method employs a photoimageable dielectric film, having a solvent content less than about 5%, and a glass transition temperature, when cured, which is greater than about 110&deg; C. A photoimageable dielectric film, is provided having from about 95% to about 100% solids, and comprising: from 0% to about 30% of the solids, of a particulate rheology modifier, from about 70% to about 100% of the solids of an epoxy resin system (liquid at 20&deg; C. comprising: from about 85% to about 99.9% epoxy resins; and from about 0.1 to 15 parts of the total resin weight, a cationic photoinitiator; from 0 to about 5% solvent, applying the photoimageable dielectric film to a circuitized substrate; and exposing the film to actinic radiation.

Method of fabricating circuitized structures

The present invention provides new methods for electroless plating of metal particularly gold and copper onto substrates, such as circuitized substrates, which reduces processing steps, reduces metal consumption, and reduces the scraping of parts due to contamination. The method employs a permanent plating resist. The method for electrolessly plating metal onto a substrate, including the following steps: providing: an uncured, photoimagable, dielectric permanent plating resist comprising: from about 10 to 80% of phenoxy polyol resin which is the condensation product of epichlorohydrin and bisphenol A, having a molecular weight of from about 40,000 to 130,000; from about 20 to 90% of an epoxidized multifunctional bisphenol A formaldehyde novolac resin having a molecular weight of from about 4,000 to 10,000; from 0 to 50% of a diglycidyl ether of bisphenol A having a molecular weight of from about 600 to 2,500; and from about 0.1 to 15 parts by weight of the total resin weight, a cationic photoinitiator; applying the permanent plating resist on the substrate; photopatterning the permanent plating resist to form apertures therein which expose areas of the substrate; and electrolessly plating metal onto the exposed areas of the substrate. The permanent plating resist is useful to protect the substrate areas including for example metallized features on the substrate, from the electroless deposition of metal during electroless plating; thus selective plating of metal is achieved. The permanent plating resist is not degraded by conventional gold or copper electroless baths. The invention also relates to circuitized structures produced by the methods of electroless plating.

Circuitized structures produced by the methods of electroless plating

A method for fabricating circuitized substrates which reduces shorts, and does not require baking and resulting film. The method employs a photoimageable dielectric film, having a solvent content less than about 5%, and a glass transition temperature, when cured, which is greater than about 110&deg; C. A photoimageable dielectric film is provided having from about 95% to about 100% solids, and comprising: from 0% to about 30% of the solids, of a particulate rheology modifier; from about 70% to about 100% of the solids of an epoxy resin system (liquid at 20&deg; C.) comprising: from about 85% to about 99.9% epoxy resins; and from about 0.1 to 15 parts of the total resin weight, a cationic photoinitiator; from 0 to about 5% solvent; applying the photoimageable dielectric film to a circuitized substrate; and exposing the film to actinic radiation.

A cavity-type chip module. The module is formed with an adhesive joining layer of photoimageable material interposed between a metal stiffener and a laminate top layer with a central aperture defined in the top layer. The photoimageable material is exposed to actinic radiation, except for an area corresponding to the aperture in the top layer. The unexposed area of photoimageable material is developed away to form a window in the joining layer. The top layer, joining layer, and stiffener are laminated together with the window and aperture aligned, and with a portion of the stiffener spanning the aperture to define a cavity in the resulting substrate. The removal of the unexposed photoimageable material, and the selective exposure of the joining layer to actinic radiation, keep the cavity free of photoimageable material and inhibit bleeding of the photoimageable material into the cavity from its inner edge. As a result, a semiconductor component can be flush mounted in the cavity with optimal thermal conductivity to the metal stiffener.

Method of forming a chip carrier by joining a laminate layer and stiffener

A novel method of filling apertures in substrates, such as through holes, is provided. The method utilizes a phtoimageable film, and comprises the following steps: applying a photoimagable, hole fill film over the apertures, preferably having a solvent content of 7-18%; reflowing the hole fill film to flow into the apertures; exposing the hole fill film to actinic radiation, preferably ultraviolet light, through a phototool, which preferably has openings slightly larger than the diameter of the apertures; then at least partially curing the hole fill film; and developing the hole fill film to remove the unexposed hole fill film. Thus, the apertures may be selectively filled. After the apertures are filled, the hole fill film is cured. Thereafter, the substrate may be subjected to further processing steps, for example, nubs of cured hole fill film can be removed. If desired, the substrate is circuitized and overplated with gold.

Methods for selectively filling apertures

Laminate substrate having joining layer of photoimageable material

A novel method of filling apertures in substrates, such as through holes, is provided. The method utilizes a photoimageable film, and comprises the following steps: applying a photoimagable, hole fill film over the apertures; reflowing the hole fill film to flow into the apertures; exposing the hole fill film to actinic radiation, preferably ultraviolet light, through a phototool, which preferably has openings slightly larger than the diameter of the apertures; then at least partially curing the hole fill film; and developing the hole fill film to remove the unexposed hole fill film. An advantage of the present method is that the apertures may be selectively filled. After the apertures are filled, the hole fill film is cured, preferably by baking. Thereafter, the substrate is preferably subjected to further processing steps; for example, nubs of cured hole fill film are preferably removed. If desired, the substrate is circuitized. If desired, features are gold plated, such as for example, electrolessly gold plated. The hole fill film preferably has solids which comprise 0 to about 20% of a thixotrope and about 80% to about 100% parts of an epoxy resin system; the epoxy resin system comprises: from about 10% to about 80% of phenoxy polyol resin which is the condensation product of epichlorohydrin and bisphenol A, having a molecular weight of from about 40,000 to about 130,000; from about 20% to about 90% of an epoxidized multifunctional bisphenol A formaldehyde novolac resin having a molecular weight of from about 4,000 to about 10,000; from about 35% to about 50% of a diglycidyl ether of bisphenol A, preferably halogenated, and having a molecular weight of from about 600 to about 2,500; and from about 0.1 to about 15 parts by weight of the total resin weight, a cationic photoinitiator. The invention also relates to circuitized structures produced according to the method.

Methods of selectively filling apertures

A method of fabricating an electronic package having an organic substrate. The substrate is formed of fiberglass and epoxy. In order to additively circuitize the electronic package substrate, an organic polyelectrolyte is deposited onto the organic substrate. A colloidal palladium-tin seed layer is deposited atop the organic polyelectrolyte. This is followed by depositing a photoimageable polymer atop the seed layer, and photolithographically patterning the photoimageable polymer to uncover portions of the seed. layer. The uncovered portions of the seed layer are catalytic to the electroless deposition of copper. In this way a conductive layer of copper is deposited atop the uncovered seed layer. The organic polyelectrolyte is deposited from an aqueous solution at the pH appropriate for the desired seed catalyst coating, depending on the ionizable character of the particular polyelectrolyte employed.

Organic electronic package and method of applying palladium-tin seed

A method of fabricating an electronic package having an organic substrate. The substrate is formed of fiberglass and epoxy. In order to additively circuitize the electronic package substrate, an organic polyelectrolyte is deposited onto the organic substrate. A colloidal palladium-tin seed layer is deposited atop the organic polyelectrolyte. This is followed by depositing a photoimagable polymer atop the seed layer, and photolithographically patterning the photoimagable polymer to uncover portions of the seed layer. The uncovered portions of the seed layer are catalytic to the electroless deposition of copper. In this way a conductive layer of copper is deposited atop the uncovered seed layer. The organic polyelectrolyte is deposited from an aqueous solution at the pH appropriate for the desired seed catalyst coating, depending on the ionizable character of the particular polyelectrolyte employed.

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Brackney, PA, United States of America

Heike Marcello