Abstract: An apparatus and method for vacuum printing inks onto a substrate in which the printing screen is mounted in a pivotable screen holder. The substrate is positioned on a printing platen and adhered to the platen during the printing operation by a vacuum hold-down system. The platen rests upon a product carrier which may be moved in a direction normal to the surface of the printing platen in order to adjust the spacing between the substrate and printing screen. The printing screen may be registered with the substrate by adjusting the position of the screen holder along two axes defining the screen plane and about a third axis normal to the screen plane. During printing the screen is deflected into contact with the substrate by a vacuum hold-down system. The system is configured to minimize the volume of air which must be evacuated during the printing operation.

Abstract: A method and apparatus for making a template used in manufacturing printed circuit boards is disclosed. The template is made from boron nitride, silicon nitride or similar material which has a melting temperature higher than the melting temperature of the metal forming the conductors in the printed circuit board, is readily machinable or moldable with the desired circuit pattern, and does not adhere to the metal conductors after the metal particles have been melted onto the substrate.

Abstract: A method for the reduction of oxides in a powder metal requires a predetermined quantity of powder to be loaded into a retort tube or other type of furnace which is pumped down to a vacuum less than about 5.times.10.sup.-6 Torr. The retort is ramped up to a temperature of about 500.degree.-750.degree. C. and maintained at that temperature under high vacuum for about 30-60 minutes to obtain reduction of oxides and de-gasing of copper powders of screen mesh sizes of -100. A hydrogen partial pressure of 150 microns to 20 mm of Hg may be valved into the system from standard grade hydrogen gas 15 minutes into approximately the 30-60 minute hold temperature ramp and then valved off on cooling to 400.degree. C. to improve oxide removal. The system is returned to the high vacuum mode and furnace cooled to room temperature.

Abstract: Electrical conductors on printed circuit board substrates are made from metal particles having a particular particle size range distribution used to control the flow of molten metal when entering the liquid phase such as during fusing. The distribution can follow a bimodal curve wherein the mixture contains approximately 45% by weight of large copper particles between 44-74 microns, 45% by weight of small copper particles less than 5 microns in size with the remaining 10% by weight being particles with sizes between the smaller and larger sizes.

Abstract: A method and apparatus is disclosed for curing metal particles into continuous metal conductors on a nonconducting substrate. The apparatus includes a generator for supplying radio frequency energy through an impedance matching circuit to a coil positioned proximate to the substrate. The coil and substrate are placed in a chamber which is evacuated prior to curing and then pressurized with nitrogen gas. The electromagnetic flux lines generate eddy currents in the particles which heat them until at least some melt, thereby converting the metal particles into continuous conductors.

Abstract: A package contains conductive inks or slurries adapted for attachment to a screen printer for applying the inks to a substrate for firing into printed circuit boards. The bag interior containing the ink is formed between a liquid and gaseous impermeable top wall connected along its periphery to a bottom wall formed with openings through which the ink is adapted to migrate towards the print screen under vacuum. A seal member extends around the entire periphery of the bag and is adapted to sealingly mate with a corresponding fastening element attached to the print frame to form an air seal between the bag and print frame in operative position. A removable, peel-away cover normally covers the screen bottom wall to allow the bag to have a long shelf life.