Abstract: A flexible circuit board having an improved protective coverlay is provided. The product flexible circuit board comprises a flexible, dielectric substrate, one or more electrical conductors carried on the surface thereof, one or more electrical contact bumps in electrical communication with the conductors, and an improved protective coverlay electrically insulating the electrical conductors. The coverlay, which is a solid, tack-free film bonded to the surface of the dielectric substrate, is formed in situ from one or more layers of flexible, dielectric, polymeric adhesives and avoids the use of a pre-formed, self-supporting film.

Abstract: Disclosed is a method of fabricating a microelectronic package, especially a microelectronic package having copper circuitization on a dielectric substrate. The method includes the steps of depositing, imaging, developing the photoresist for additive circuitization, and forming a pattern of copper circuitization on the so exposed portions of the package. In order to avoid the formation of deleterious air bubbles on the exposed walls of the imaged and developed resist, the panel is exposed to and wetted by a liquid mist.

Abstract: A method of solder leveling in printed circuit boards or other circuitized substrates. Flux is first applied to the surface of the substrate to be soldered. Molten solder is then applied to the fluxed surface after which the soldered substrate is cooled to a temperature below 300.degree. F. Molten solder is then again applied to the previously soldered surface of the substrate. This last step results in leveling the solder first applied to the substrate, including removal of any solder balls which had been formed over recessed pins and flush filling of passage holes formed in the substrate. The method can be performed without regard to the surface condition of the substrate, the composition of flux and solder, whether the substrate is of the thin film type or of the thick film type, nor whether dip soldering or wave soldering techniques are used. The invention also incompasses the end product resulting from use of the method.

Abstract: A structure comprising on a substrate successive layers of metal circuitry having therebetween as a dielectric a cured polyimide composition containing a polyimide and aluminum oxide or zinc oxide or mixtures thereof.The structure is produced by a method including the following process steps:blanket screen printing a mixture containing a polyamido carboxylic acid, aluminum oxide or zinc oxide or mixtures thereof and a detackifier with the rest being a solvent on a substrate with a layer of metal circuitry thereon,drying the deposited layer at a temperature between about 25.degree. and about 120.degree. C.,selectively etching holes into the deposited layer where vias between adjacent layers of metal circuitry are needed,curing the deposited layer at a temperature between about 300.degree. and about 400.degree. C. andforming another layer of metal circuitry.

Abstract: A machine for forming a head and a bulge on a copper pin and to connect the pin to a ceramic substrate by a single application of impact force at high velocity and controlled energy conditions includes an air cylinder within which a piston of controlled mass moves due to the effect of compressed air stored in an accumulator. A die block includes a two dimensional array of holes into which are fitted pin blanks that extend above the surface of the die block and on which is fitted a substrate having an identical array of pin holes formed therein. The pins are fitted within the die block and on the substrate such that a predetermined length of the pin blank extends above the surface of the substrate and a controlled length of the pin blanks extends between the substrate and the die block. The pins are retained within the die against axial movement and the holes in the substrate and die block provide radial restraint to the pins following the application of the impact force.

Abstract: Ceramic substrates are pinned using powdered metallurgy pins formed in situ on the substrate.

Abstract: An elongated member is provided in the discharge orifice of a spray head nozzle so that the fluid being sprayed is discharged as a hollow stream resulting inter alia in a better and more complete atomization of the fluid in coaction with a low pressure propellant.

Abstract: Cured epoxy compositions are removed from substrates by employing compositions containing an organic cyclic alcohol and a surface-active agent.

Abstract: A cleaning composition which includes N-methyl-2-pyrrolidone and an alkanolamine, and use thereof for cleaning substrates.

Abstract: A screenable and strippable solder mask composition which contains a polyepoxide or polyimide/amide; a detackifier and a high-temperature resistant filler; and use thereof for protecting predetermined areas on a substrate from the solder deposition.

Abstract: The hermetic seal of the backside of a substrate of an integrated circuit module is provided by a composition containing about 51.4 to about 60.6% by weight of an epoxy polymer; about 39 to about 48% by weight of a hardener and flexibilizing portion; and up to about 0.6% by weight of a coloring agent.