Abstract:
An alignment board for interfacing arrays of infrared detectors to a multi-layer module concerns an insulating board having a multiplicity of conductive vias with insulating sealing plugs and enlarged metallic pads that are attached to the ends of the vias. Preferably, an insulating layer is formed on opposing sides of the board. Openings are delineated in the layer coinciding with the metallic pads, and preferably solder contacts are deposited in the openings. A multi-layer module may be attached to one side of the alignment board using reflow solder processes. Then, arrays of infrared detectors may be attached to the opposing side of the alignment board using a lower-temperature reflow soldering process. The alignment board facilitates the interfacing and assembly of the focal plane of infrared detection systems.
Abstract:
Making a heat sink and printed circuit board assembly by providing a heat exchange element on the heat sink which lies in heat exchange contact with the heat sink and passes therethrough. After locating the board and heat sink in relative positions apart and with the heat exchange element aligned with an electronic component on the board, a settable thermally conductive compound is injected through a hole in the heat exchange element to bond it to the electrical component. The heat sink is detachable from the heat exchange element to expose the side of the board carrying the components so that maintenance or repair may be performed. Subsequently the heat sink is returned into its position in the assembly.
Abstract:
A pair of electrical circuits (20, 22), which may be both flexible or one flexible and one rigid, are interconnected by projections, such as bumps (24) and rings (26) . The projections are formed from substantially inelastic dielectric material, such as an epoxy defining bumps (34) and rings (36), which are plated with copper (38). Projections (24, 26) of one circuit are disposed to interconnect with mating projections on the other circuit, the interconnection being bump to bump, bump to ring, or bump to pad. The projections may be formed on a copper-clad substrate (42) or on plated-through holes (72) on a printed wiring board (70). Alternately, polygonal pads (94) on a circuit (90) may be joined to a projection. Further, a plurality of bump projections (106), electrically connected to the same or different circuits, may collectively interconnect with a single oval ring projection (108).
Abstract:
A structure and method are disclosed for making high density circuit board. Using photosensitive or other dielectric materials over a circuitized power core, vias and lands are opened up, filled with joining metal and aligned with the next level, eliminating a major registration problem in building up a high density composite and reducing the number of steps in the manufacturing process.
Abstract:
Circuit boards with imbedded traces, which may form grooves or trenches are provided. The traces may be at least partially filled with a reflowable conductive material such as solder. The grooves may be selectively furnished with solder while other regions may be empty or void of solder. In assembling electronic components, with or without extended leads, such as surface mount integrated circuits or chips, to the solder core circuit boards, the leads may be placed within the regions of the grooves without solder (contact regions) and then the circuit board may be heated selectively or as a whole to reflow the solder to the bonding or contacting regions to bond the traces to the leads upon cooling. Circuit boards having surface mount devices on both sides may be formed in this manner. Further, tape automated bonded or TAB mounted devices may be directly placed into and bonded to the traces or solder core circuit boards with minimum exposure of the excised TAB leads prior to assembly. In one form, the grooves are plated with copper before they are filled with solder. Alternatively, the solder may be present only in cavities or pockets next to the contact regions where the component lead will connect with the conductive material pattern.
Abstract:
A printed circuit panel is selectively coated to protect circuits which may be exposed to deleterious chemicals during the electroplating of connector tabs. The apparatus has a mechanism for gripping and transporting the circuit panels through multiple stations including cleaning, drying, coating and curing in a vertical position at variable speeds. The coating station has multiple wipers movable in a vertical plane to apply a polymer to the circuit panel at a controlled volume on various levels. The wipers each have a leading edge in contact with the panel surface to be coated and an adjustable back edge spaced apart from the panel surface to be coated with the polymer flowing to the panel between the two edges.
Abstract:
A process of forming plates through-holes in a printed circuit board involves placing a film of fluid ink having electrically conductive properties on a side wall of the hole, curing the film to a solid and electroplating a layer of metal on the conductive ink film. The conductive ink preferably is a composition including conductive particles such as carbon and silver flakes. The ink also preferably includes a thermosetting or radiation curable binder and a thinner. The film of ink is cured before the layer of metal is electroplated thereon. The plated through-hole is protected from the etchant when the conductors are etched by placing a radiation curable putty material into the hole, curing it, and then depositing a layer of resist on top of the cured putty and a conductive sheet clad to the substrate of the circuit board.
Abstract:
An electrically and mechanically sound conductive bond between layers of a multi-layer plated through hole circuit board is produced by depositing a layer of noble metal over the surfaces to be joined, juxtaposing the noble metal coated layers and subjecting them to a combination of pressure and heat for a sufficient period of time. Excellent results have been obtained in a multi-layer circuit board for a microstrip microwave antenna with 0.002 inch thick polished silver layers at bonding pressures of 490 to 575 psi and temperatures of 560 to 580 degrees F. for time periods of 20 to 30 minutes.
Abstract:
A solder resist paste having the feature that it is relatively easily removed is disclosed. The paste is comprised of a liquid polyglycol (e.g. Pluronic 25R2 by BASF) and either Kaoline or talc powder. In operation, the paste is selectively applied to holes in the PCB which it is desired to keep open during a soldering process. The paste is then washed out of the holes, additional components mounted via those holes, and soldered into place.
Abstract:
The process and device in accordance with the present invention allow the simple and economic manufacture of printed circuit boards, wherein the metal of the conductors as well as the one covering the hole walls is identical with the metal being etched away from the areas between the conductors.According to this process, a one-or two-sided metal-coated base material is used which, upon production of the hole pattern, is provided in a known manner with a metal layer of desired thickness, covering the surface of the metal foil as well as the hole walls. Subsequently, a masking layer is applied by screen printing a positive image of the desired circuit pattern on the surface(s). In the following process step, the holes are filled with an ink by means of a screen printing stencil. In accordance with one embodiment of the invention, the ink used forms an etch-resistant surface film when drying. Upon etching, the masking layer as well as the surface film and the hole fillings are removed with a suitable solvent.The screen printing stencil comprises a carrier screen fixed to a frame, said carrier screen being provided on its side facing the surface to be printed with a metal or plastic foil, said screen and foil being provided with holes at locations in proportion to the hole pattern in the base material.