Abstract: A process of fabricating a circuitized structure is provided. The process includes the steps of providing an organic substrate having circuitry thereon; applying a dielectric film on the organic substrate; forming microvias in the dielectric film; sputtering a metal seed layer on the dielectric film and the microvias; plating a metallic layer on the metal seed layer; and forming a circuit pattern thereon.

Abstract: 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.

Abstract: A process of fabricating a circuitized substrate is provided which comprising the steps of: providing an organic substrate having circuitry thereon; applying a dielectric film on the organic substrate; forming microvias in said dielectric film; sputtering a metal seed layer on the dielectric film and in said microvias; plating a metallic layer on the metal seed layer; and forming a circuit pattern thereon.

Abstract: 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.

Abstract: A process of fabricating a circuitized substrate is provided which comprising the steps of: providing an organic substrate having circuitry thereon; applying a dielectric film on the organic substrate; forming microvias in said dielectric film; sputtering a metal seed layer on the dielectric film and in said microvias; plating a metallic layer on the metal seed layer; and forming a circuit pattern thereon.

Abstract: Simple, environmentally friendly developers and strippers are disclosed for free radical-initiated, addition polymerizable resists, cationically cured resists and solder masks and photoresists. Both the developers and the strippers include benzyl alcohol, optionally also including a minor amount of methanol, ethanol, isopropyl alcohol, propylene glycol monomethylacetate, ethylene glycol monomethyl ether, formamide, nitromethane, propylene oxide, or methyl ethyl ketone, acetone and water.

Abstract: 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.

Abstract: A process of tenting plated through holes with a photoimageable dielectric is provided which includes a dielectric film comprising a photoimageable epoxy based resin layer and a peelable polyester layer. In accordance with the process of the present invention, the peelable polyester layer of the dielectric film is removed prior to baking, developing, patterning or curing the structure.

Abstract: 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.

Abstract: The present invention provides a novel method of reducing the amount of seed deposited on polymeric dielectric surfaces. The method comprises the following steps: providing a work-piece coated with a polymeric dielectric layer; baking the work-piece to modify the surface of the polymeric dielectric layer; then applying the seed to polymeric dielectric layer and electrolessly plating metal to the seed layer. The invention also relates to a circuit board produced by the method of the present invention.

Abstract: The present invention provides a novel method of reducing the amount of seed deposited on polymeric dielectric surfaces. The method comprises the following steps: providing a work-piece coated with a polymeric dielectric layer; baking the work-piece to modify the surface of the polymeric dielectric layer; then applying the seed to polymeric dielectric layer and electrolessly plating metal to the seed layer. The invention also relates to a circuit board produced by the method of the present invention.

Abstract: Bridging between electrically conductive circuit features during conformal plating is prevented by avoiding the deposition of catalytic seed material onto non-circuit areas of the substrate. Preparatory to forming electrical circuit features on a nonconductive substrate by the full additive process, extraneous seed material is either trapped between two layers of a photoimageable film, whereby it is unavailable during plating, or deposited on the surface of an aqueous photoimageable film, which is removed prior to plating. The method embodying the present invention eliminates the need for seed removal after initial plating and prior to conformal plating of a precious metal over the initial plating.

Abstract: Bridging between electrically conductive circuit features during conformal plating is prevented by avoiding the deposition of catalytic seed material onto non-circuit areas of the substrate. Preparatory to forming electrical circuit features on a nonconductive substrate by the full additive process, extraneous seed material is either trapped between two layers of a photoimageable film, whereby it is unavailable during plating, or deposited on the surface of an aqueous photoimageable film, which is removed prior to plating. The method embodying the present invention eliminates the need for seed removal after initial plating and prior to conformal plating of a precious metal over the initial plating.

Abstract: 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.

Abstract: The present invention provides a method of ablative photodecomposition and forming metal pattern which attains high resolution, is convenient, and employs non-halogenated solvents. The present invention is directed to a process for forming a metal pattern, preferably circuitization on an organic substrate, preferably on a circuit board or component thereof, which comprises coating the substrate with an ablatively-removable coating comprising a polymer resin preferably an acrylate polymer resin and preferably an ultraviolet absorber. A pattern is formed in the polymer coating corresponding to the desired metal pattern by irradiating at least a portion of the polymer coating with a sufficient amount of ultraviolet radiation to thereby ablatively remove the irradiated portion of the polymer coating. Next the patterned substrate is coated with a conductive metal paste to define the metal pattern, and the conductive metal paste is cured.