Abstract:
A multiple, parallel packed column vaporizer for vaporizing a chemical having a relatively low decomposition temperature includes a shell; a plurality of parallel, vertically oriented vaporization columns arranged in the shell, each vaporization column having inner walls and upper and lower open ends; a distribution assembly for distributing the chemical substantially equally to the open upper ends of the vaporization columns, which flows downwardly therein; a heat exchanger which heats the vaporization columns to provide the heat needed to vaporize the chemical therein; and a gas supply which supplies the gas to the lower ends of the vaporization columns so that the chemical is vaporized and becomes entrained in the gas and is carried upwardly out of the vaporizer.
Abstract:
A composition including a mixture of UV curable urethane acrylate and a urethane diacrylate compounds provides an aqueous alkaline developable, flexible solder mask having excellent electrical insulation resistance under hydrolytic testing conditions at elevated temperatures.
Abstract:
Polyimidesulfone and polyimideketone resins are rendered moldable while still retaining solvent resistance and high temperature physical and mechanical properties by incorporating an aromatic diaminopolysiloxane at a level between about 1 and about 20 mole % of the total diamine content, into the polymer.
Abstract:
An apparatus for applying a phototool to a light sensitive substrate by means of a roller for applying the phototool to the substrate and a vacuum restraining means for restraining the phototool to maintain it under tension during application of the phototool to the substrate.
Abstract:
Haze-free tin oxide coatings are made from an organotin compound which ordinarily gives only hazy coatings. The improvement comprises first forming an undercoat of a haze-free tin oxide film on a substrate, preferably by decomposition of monophenyltin trichloride. Thereafter the tin oxide overcoating assumes the haze-free characteristics of the undercoat film.
Abstract:
Improved printing with polymers is achieved by interposing a liquid layer conforming to rough substrate surfaces and possibly exhibiting different characteristics from an outer surface polymer layer. This is particularly advantageous in printed wiring board (PWB) manufacture requiring solder mask coating. Thus, a two layer composite polymer coating is provided. One inner adhesive photopolymer layer is applied to the PWB in the liquid state, displacing air from PWB surface. The outer layer of the composite therefore can be epoxy, dry film or liquid polymer. Dry film thus carried on a thin plastic sheet may be overlaminated onto a liquid inner layer already on the substrate, without the need for a vacuum laminator to eliminate bubbles or a plasticizing heat step to conform the dry film to the surface. The dry film solder mask so laminated is then exposed through a phototransparency to harden the light struck dry film solder mask and light struck inner layer photopolymer, thereby cojoining the dry film solder mask, inner layer and PWB surface. A solvent washout step removes unexposed dry film solder mask and unexposed inner layer photopolymer. This provides a faster process, requires less equipment, and improves adhesion to metal conductors. This embodiment gives a high resolution product with good solder mask qualities. The outer layer need not be photoimaged. Thus, pre-patterned epoxy solder masks may be printed on the carrier sheet, partially hardened and overlaminated in registor onto liquid photopolymer-coated PWB, then exposed to light source through a phototransparency and through the pre-patterned solder mask, thereby permanently adhering the outer layer to PWB. The composite coating can be a combination of known solder mask materials, dry film, UV-curable liquid polymers and thermal-curing epoxy, chosen for desired characteristics including electrical performance, printing resolution and cost.
Abstract:
This invention relates to organotin compounds containing fluorine which are particularly useful for forming fluorine-doped tin oxide coatings by the chemical vapor deposition method. In the preferred embodiment, the compound is monobutyldichlorotin trifluoroacetate, which is prepared by reaction of monobutyltin trichloride and trifluoroacetic acid.
Abstract:
An adherent, smooth electrodeposit of chromium is produced on a nodular cast iron substrate from a chromium plating bath. The desired deposit is provided herein by activating the substrate, subjecting the activated substrate to an ultrasonic treatment, and thereafter plating chromium from a chromium plating bath. The method is particularly effective for electrodeposition of chromium on such substrates from commercial high energy efficient chromium electroplating baths, where ordinarily only roughened deposits are obtained.
Abstract:
A novel polymeric binder for use in an antifouling paint includes an acrylic or methacrylic ester monomer having selected substituted aryl or arylalkyl substituent groups in the ester moiety so that the ester is hydrolyzable at a suitable rate in seawater, and a copolymerizable ethylenically unsaturated monomer unit.
Abstract:
Polyamic acids prepared from the condensation of dianhydrides (or trianhydrides) and diamines and preferably dissolved in a suitable solvent produce polyimide shaped articles (e.g. films) relatively free of voids, pinholes, cracks and bubbles when about 0.75 to about 5 mole percent of a polysiloxane is incorporated in the backbone of the polyamic acid.