Abstract: A new flux composition, as well as corresponding methods for soldering electronic components to printed circuit boards, is disclosed. The new flux composition includes pimelic acid and two organic solvents. Significantly, the new flux composition leaves essentially no ionic residues at the completion of the soldering processes used to mount electronic components onto printed circuit boards.

Abstract: The present invention permits solder joints to be made directly to via and through holes without the solder being wicked into the vias or through holes, by filling plated through holes with an epoxy or cyanate fill composition. When cured and overplated, the fill composition provides support for the solder joint and provides a flat solderable surface for the inter-connection. In certain embodiments, the cured fill compositions, offer a further advantage of being conductive. The invention also relates to several novel methods for filling through holes with such fill compositions, and to resistors located in through holes and vias.

Abstract: A new flux composition, as well as corresponding methods for soldering electronic components to printed circuit boards, is disclosed. The new flux composition includes pimelic acid and two organic solvents. Significantly, the new flux composition leaves essentially no ionic residues at the completion of the soldering processes used to mount electronic components onto printed circuit boards.

Abstract: A fusible conductive adhesive for making electrical and mechanical contact is provided. The fusible conductive adhesive contains a polymer having a glass transition temperature and a thermal expansion co-efficient. The thermal expansion co-efficient of the polymer is in the range of about 5 parts per million per degree centigrade to about 10 parts per million per degree centigrade along a z-axis. The polymer is loaded with a conductive material having a sintering temperature range overlapping the glass transition temperature of the polymer. In addition, the loading of the conductive material in the polymer is in the range of about 15% to about 20% conductive material by weight based on the total weight of the polymer and the conductive material.

Abstract: Disclosed is a method of reworking a circuit panel, and a reworked circuit panel structure. The method includes providing a conformal, polymeric, dielectric coating or coatings on the surface of the panel, providing conductive circuitization atop the conformal, polymeric, dielectric coating or coatings on the surface of the panel, and providing a top conformal, polymeric, dielectric coating atop the conductive circuitization layer. Also disclosed is a rerouted circuit panel having at least two surface features that are connected by a rerouted current lead. The current lead is formed of a dielectric encapsulated conductor electrically joining the two surface features. The dielectric encapsulated conductor structure includes a conformal, polymeric dielectric bottom layer adherent to a surface of the circuit board, with a provided conductor on the conformal, polymeric dielectric layer, and a conformal, polymeric dielectric layer provided atop the provided conductor.

Abstract: Methods and apparatus are provided for applying solder in precise amounts to fine pitch leads such as those suitable for direct chip attachment (DCA) or flip-chip applications by using a heated platen to apply pressure to solder overlaying a plurality of lands on circuitized substrate. In one embodiment paste solder screened through a mask having apertures each corresponding to a plurality of land locations. In another embodiment, a web of solder foil is accurately positioned over a plurality of fine pitch lands. In each embodiment, a heated platen includes at least one active element corresponding in size and shape to the area having a plurality of fine pitch lands. A third embodiment includes individual platens for lands to which solder is to be applied.

Abstract: An acid copper plating bath and process for using with electropositive metals such as aluminum and tungsten is described, wherein the bath contains sulfuric acid, copper sulfate, in solution with urea as a levelling agent, a cationic surfactant as a wetting agent and an ester of a sulfonic acid, Beta-phenylethyltosylate as a brightening agent.

Abstract: A chemical polishing bath and process are disclosed for pretreating aluminum and its alloys prior to plating or anodizing operations, which bath and process produce a mirrorlike finish.

Abstract: A novel electroless plating bath composition and method for the use thereof, are described for depositing a layer of nickel on anodized aluminum substrates for facilitating direct attachment of electronic chips thereto; the bath composition being a neutralized solution of nickel sulfate, sodium citrate, lactic acid and dimethylbomine in deionized water.

Abstract: An additive plating bath and process are described for use in printed circuit manufacturing for applying copper to thick film patterns, said bath includes a low concentration of sulfuric acid, copper sulfate, urea, glycerin and a surface active agent in an aqueous solution.

Abstract: A process for preparing aluminum alloy substrates for use in electrical packaging includes anodizing in an aqueous bath solution containing sulfuric acid, citric acid, urea, and ammoniated colloidal silica; the latter three components being a complexing agent, a leveling agent and a stabilizing agent, respectively, so as to result in an oxide layer having an amorphous structure which eliminates the necessity of sealing thick anodic coating.

Abstract: An anodizing bath for aluminum alloys is disclosed; the aqueous bath solution contains sulfuric acid, citric acid, urea, and ammoniated colloidal silica; the latter three components being a complexing agent, a leveling agent and a stabilizing agent, respectively, so as to result in an oxide layer having and amorphous structure which eliminates the necessity of sealing thick anodic coating.

Abstract: A composite substrate suitable for use as substrates for printed circuitry to which surface mountable components may be attached is disclosed. The substrate material comprises an alloy having a low coefficient of thermal expansion, to which aluminum is laminated and which is subsequently surface treated to produce a dielectric layer suitable to receive printed circuitry.

Abstract: A new alloy material for use in electrical contacts is disclosed, comprising by weight______________________________________ Beryllium 1-2% Palladium 2-20%; and ______________________________________the balance of nickel.

Abstract: Nickel and copper are plated over a thick anodic coating on an aluminum substrate as a step in the manufacture of printed circuit board substrates.