Abstract: A method for attaching adherent metal components, particularly a copper film, on at least one surface of a polyimide substrate is provided. The method comprises the steps of: exposing at least one surface of the polyimide substrate to a reactive gas plasma that provides a level of ion bombardment of the polyimide surface sufficient to disrupt at least a portion of the imide groups on the surface and to form reactive carboxylate groups, carbonyl groups and other carbon-oxygen functional groups on the surface; and then depositing a metal film onto the chemically-modified surface without intervening exposure to air. The present invention also provides a copper-coated polyimide product comprising a polyimide substrate having a substantially smooth and chemically-modified surface and a copper film directly attached to the surface, i.e., the product is free of a polymeric adhesive layer or tie coat between the surface of the polyimide substrate and the copper film.

Abstract: A metal alloy solder ball comprising a first metal and a second metal, the first metal having a sputtering yield greater than the second metal. The solder ball comprises a bulk portion having a bulk ratio of the first metal to the second metal, an outer surface, and a surface gradient having a depth and a gradient ratio of the first metal to the second metal that is less than the bulk ratio. The gradient ratio increases along the surface gradient depth from a minimum at the outer surface. The solder ball may be formed by the process of exposing the ball to energized ions of a sputtering gas for an effective amount of time to form the surface gradient.

Abstract: An electronic module having enhanced adhesion at the chip passivation and underfill interface is disclosed. The surface of the chip passivation is chemically modified to a sufficient depth such that the cured passivation is more reactive. The modified surface is treated with a polyamine preferably having a cyclic amine group extending from a preferably aliphatic backbone. During reflow of the solder joints of the electronic module by heating, the modified passivation reacts with the polyamine at the amine functionality. Following underfill of the electronic module with a polymeric material, preferably an epoxy resin, the polyamine on the surface of the passivation reacts with the underfill material during curing of the underfill material. The resulting electronic module is more robust since the amine acts as a chemical anchoring site for both the modified passivation and the underfill material.

Abstract: A process for promoting fluxless soldering of a mass of bulk solder having a bulk ratio of a first metal to a second metal, such as lead-enriched solder that has significantly more lead than tin. The process comprises exposing the bulk solder to energized ions of a sputtering gas in the presence of a halogen, such as fluorine, and forming a surface layer having a desired surface layer ratio of the first to the second metal that is less than the bulk ratio, the surface layer further comprising an uppermost surface film containing the fluorine or other halogen. After the solder exposure and surface-layer formation, the process may further comprise electrically joining the solder to a surface without using externally-applied flux. This process enables the joining step to be performed at less than 300° C., at approximately 180° C.

Abstract: A method and structure is provided for preventing wetting or bleed of an adhesive, such as an epoxy, onto noble metal wire bond pads on the surface of a dielectric substrate when attaching an I/C chip to the substrate. The method includes treating the wire bond pads with a chemical composition which prevents bleeding onto the surfaces of the wire bond pads by a component of the epoxy. The chemical composition is a chemical which will provide “Self-Assembled Monolayers” (SAMs) on the surface of the gold. These compositions are characterized by a molecule having at least one group, such as a mercaptan or disulfide, connected to a hydrocarbon moiety, such as a (CH2)x chain. The affinity of the thiol or sulfur-containing portion of the molecule chemically bonding with the noble metal provides a relatively strong attachment of the molecule to the metal surface.

Abstract: An electronic module having enhanced adhesion at the chip passivation and underfill interface is disclosed. The surface of the chip passivation is chemically modified to a sufficient depth such that the cured passivation is more reactive. The modified surface is treated with a polyamine preferably having a cyclic amine group extending from a preferably aliphatic backbone. During reflow of the solder joints of the electronic module by heating, the modified passivation reacts with the polyamine at the amine functionality. Following underfill of the electronic module with a polymeric material, preferably an epoxy resin, the polyamine on the surface of the passivation reacts with the underfill material during curing of the underfill material. The resulting electronic module is more robust since the amine acts as a chemical anchoring site for both the modified passivation and the underfill material.

Abstract: A method for bonding heat sinks to packaged electronic components comprises the steps of: (a) exposing to a plasma a surface of a molded polymer formed on a substrate; (b) allowing the plasma to at least partially convert silicon-containing residue on the surface to silica; and (c) bonding an article to the surface by applying an adherent between the article and the surface. Often, the silicon-containing residue is silicone oil, a mold release compound, which may prevent the formation of a bond when using conventional bonding methods and materials. The silica layer formed on the surface of the molded polymer assists in formation of a proper bond. The plasma may be an oxygen plasma and the adherent may be selected from either a heat cured silicone-based paste adhesive with a metal oxide filler or a heat cured porous polymer film impregnated with adhesive.

Abstract: A method is provided for selectively metallizing one or more three-dimensional materials in an electronic circuit package comprising the steps of forming a layer of seeding solution on a surface of the three-dimensional material of interest, exposing this layer to light of appropriate wavelength, resulting in the formation of metal seed on regions of the three-dimensional material corresponding to the regions of the layer of seeding solution exposed to light; removing the unexposed regions of the layer of seeding solution by subjecting the exposed and unexposed regions of the layer of seeding solution to an alkaline solution. Thereafter, additional metal is deposited, e.g., plated, onto the metal seed using conventional techniques. Significantly, this method does not involve the use of a photoresist, or of a corresponding chemical developer or photoresist stripper.

Abstract: A process for altering surface properties of a mass of metal alloy solder comprising a first metal and a second metal. The process comprises exposing the mass to energized ions to preferentially sputter atoms of the first metal to form a surface layer ratio of first metal to second metal atoms that is less than the bulk ratio. The solder may be located on the surface of a substrate, wherein the process may further comprise masking the substrate to shield all but a selected area from the ion beam. The sputtering gas may comprises a reactive gas such as oxygen and the substrate may be an organic substrate. The process may further comprise simultaneously exposing the organic substrate to energized ions of the reactive gas to roughen the organic substrate surface.

Abstract: A method for bonding heat sinks to packaged electronic components comprises the steps of: (a) exposing to a plasma a surface of a molded polymer formed on a substrate; (b) allowing the plasma to at least partially convert silicon-containing residue on the surface to silica; and (c) bonding an article to the surface by applying an adherent material between the article and the surface. Often, the silicon-containing residue is silicone oil, a mold release compound, which may prevent the formation of a bond when using conventional bonding methods and materials. The silica layer formed on the surface of the molded polymer assists in formation of a proper bond. The plasma may be an oxygen plasma and the adherent material may be selected from either a heat cured silicone-based paste adhesive with a metal oxide filler or a heat cured porous polymer film impregnated with adhesive.

Abstract: A method for attaching adherent metal components, particularly a copper film, on at least one surface of a polyimide substrate is provided. The method comprises the steps of: exposing at least one surface of the polyimide substrate to a reactive gas plasma that provides a level of ion bombardment of the polyimide surface sufficient to disrupt at least a portion of the imide groups on the surface and to form reactive carboxylate groups, carbonyl groups and other carbon-oxygen functional groups on the surface; and then depositing a metal film onto the chemically-modified surface without intervening exposure to air. The present invention also provides a copper-coated polyimide product comprising a polyimide substrate having a substantially smooth and chemically-modified surface and a copper film directly attached to the surface, i.e., the product is free of a polymeric adhesive layer or tie coat between the surface of the polyimide substrate and the copper film.

Abstract: The present invention comprises a method of making a circuitized structure. The method comprises the steps of providing a substrate coated with a polymeric dielectric layer, treating the substrate with alkali, baking the substrate to modify the surface of the polymeric dielectric layer, applying a seed layer to the polymeric dielectric layer and applying a conductive layer to the seed layer. The invention also comprises a printed circuit structure produced by the method of the present invention.

Abstract: A method of making a flip chip package that maintains flatness over a wide temperature range and provides good heat dissipation is described. A laminate substrate is electrically connected to electrical contacts disposed on a chip and underfill material is applied between the soldered connections. A body, for example an uncured dielectric material, is applied to the chip, the laminate substrate, a thermally conductive member or combinations thereof, and thermally conductive member is disposed adjacent to the surface of the chip that is opposite the surface connected to the laminate substrate. The body is extruded between the chip and the thermally conductive member. The thickness of the thermally conductive member is determined by balancing the stiffness and the CTE of both the thermally conductive member and the laminate substrate, and the length and width of the thermally conductive member may vary but are at least the size of the corresponding length and width of the chip.

Abstract: A method for forming a flip-chip-on-board assembly. An integrated circuit (IC) chip having a polyimide passivation layer is joined to a chip carrier via a plurality of solder bumps which electrically connect a plurality of contact pads on the IC chip to corresponding contacts on the chip carrier. A space is formed between a surface of the passivation layer and a surface of the chip carrier. A plasma is applied, to chemically modify the a surface of the chip carrier and the passivation layer of the IC chip substantially without roughening the surface of the passivation layer. The plasma is either an O.sub.2 plasma or a microwave-generated Ar and N.sub.2 O plasma. An underfill encapsulant material is applied to fill the space. The plasma treatment may be performed after the step of joining. Then, the chip and chip carrier are treated with the plasma simultaneously. Alternatively, the IC chip and chip carrier may be treated with the plasma before they are joined to one another.

Abstract: A process for altering surface properties of a mass of metal alloy solder comprising a first metal and a second metal. The process comprises exposing the mass to energized ions to preferentially sputter atoms of the first metal to form a surface layer ratio of first metal to second metal atoms that is less than the bulk ratio. The solder may be located on the surface of a substrate, wherein the process may further comprise masking the substrate to shield all but a selected area from the ion beam. The sputtering gas may comprises a reactive gas such as oxygen and the substrate may be an organic substrate. The process may further comprise simultaneously exposing the organic substrate to energized ions of the reactive gas to roughen the organic substrate surface.

Abstract: A method is provided for selectively metallizing one or more three-dimensional materials in an electronic circuit package comprising the steps of forming a layer of seeding solution on a surface of the three-dimensional material of interest, exposing this layer to light of appropriate wavelength, resulting in the formation of metal seed on regions of the three-dimensional material corresponding to the regions of the layer of seeding solution exposed to light; removing the unexposed regions of the layer of seeding solution by subjecting the exposed and unexposed regions of the layer of seeding solution to an alkaline solution. Thereafter, additional metal is deposited, e.g., plated, onto the metal seed using conventional techniques. Significantly, this method does not involve the use of a photoresist, or of a corresponding chemical developer or photoresist stripper.

Abstract: A method is provided for selectively metallizing one or more three-dimensional materials in an electronic circuit package comprising the steps of forming a layer of seeding solution on a surface of the three-dimensional material of interest, exposing this layer to light of appropriate wavelength, resulting in the formation of metal seed on regions of the three-dimensional material corresponding to the regions of the layer of seeding solution exposed to light; removing the unexposed regions of the layer of seeding solution by subjecting the exposed and unexposed regions of the layer of seeding solution to an alkaline solution. Thereafter, additional metal is deposited, e.g., plated, onto the metal seed using conventional techniques. Significantly, this method does not involve the use of a photoresist, or of a corresponding chemical developer or photoresist stripper.

Abstract: The present invention provides a novel method for improving the adhesion of polymers, particularly adhesives, to nickel surfaces. The method involves contacting the nickel surface with a hydrogen peroxide solution having a temperature of at least about 40.degree. C. for a time sufficient to form a wettable oxide surface having a water contact angle of less than about 10.degree..

Abstract: The adhesion of chromium-copper layer to polyimide has been greatly improved by a method which provides controlled reduction, rather than total elimination, of water content in the polyimide. The electronic packaging device which incorporates the flexible circuit prepared by the method exhibits greatly improved reliability. It is believed that the invention can be used to improve the adhesion between other organic materials having moisture affinity and materials comprising in-organics or between two organic materials.

Abstract: A copper layer is coated onto an organic polymeric substrate in the presence of a gas containing nitrogen and a noble gas.