Abstract: A non-hardening, solvent removable hydrophobic conformal coating is provided for electronic devices, such as printed circuit boards. The coating material comprises a metal alkyl benzyl sulfonate, together with a carrier and a solvent. The metal alkyl benzyl sulfonate may include compounds such as calcium eicosanylbenzyl sulfonate. The carrier may be any oxidized hydrocarbon, such as lauryl ethanoxylate, for example, and the solvent may be any low boiling aliphatic hydrocarbon. Though the coating is impervious to water, it may be readily and selectively removed using a small quantity of a non-polar organic solvent, such as mineral spirits or terpenes. Thus, although the electronic device is protected from corrosion, electromigration and physical harm by the coating, the coating may be easily, quickly and selectively removed in the event a component needs replacement, repair or adjustment.

Abstract: A method of making a pad array chip carrier package is disclosed. A semiconductor device (10) is bonded to a ceramic substrate (12). The semiconductor device may be attached to the substrate by wirebonding, tab bonding or flip chip bonding. The bonded assembly (16) is then attached to a flexible temporary support substrate (18) by means of an adhesive (19). The entire assembly is then placed into a mold cavity (20 and 22) and registered against the temporary support substrate (18). Plastic material (30) is molded about the semiconductor device and associated wirebonds in order to encapsulate the device. After removal from the mold, the encapsulated assembly is removed from the temporary support substrate (18) by peeling the temporary support substrate (18) from the circuit substrate.

Abstract: A method of manufacturing a ceramic substrate with improved mounting pad location tolerances. The method begins with a green non-dimensionally stable ceramic base 10 to which at least one conductive layer 15, 16 such as a tungsten mixture is screen printed. The tungsten layer locationally defines a pattern including pads 15. This composite assembly is subsequently stabilized as in firing and a second insulating ceramic slurry layer with openings 29 located over the relative larger pads is screen printed on the stabilized composite assembly. This method eliminates tolerances in final mounting pad location due to unpredictable shrinkage and yet maintains excellent mounting pad adhesion since the entire pad overlays some portion of the tungsten pad.

Abstract: A tacking agent is provided for use in temporarily adhering electronic components and providing fluxing properties for soldering electronic assemblies. The tacking agent comprises a fluxing agent and a tackifier. The fluxing agent is composed of one or more carboxylic acids having the formula ##STR1## where R is an alkyl group containing from 1 to 6 carbon atoms, R' is selected from the group consisting of hydrogen and hydroxyl, and R" is selected from the group consisting of hydrogen, hydroxyl and carboxyl. The tackifier comprises one or more alcohols, aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, or polymers. The tacking agent is deposited onto a printed circuit board or other substrate, the electronic components are placed into the deposited tacking agent and soldered. During solder reflow the fluxing agent provides fluxing action for the soldering process, and the tackifier volatilizes, leaving little or no residue on the printed circuit board.

Abstract: An integrated circuit package (10) is formed to reveal the active circuitry (15) on the die surface. An integrated circuit die (12) is mounted on a die mounting portion (32) of a metal lead frame (30) in such a manner that the die is supported on the lead frame by the perimeter portion of the die. The active circuitry (15) on the die is connected to the various metal frame leads (33) by wire bonds (18) between the bond pads on the die and the metal lead frame. Plastic molding material (50) is then molded to encapsulate the wire bond pads (17), the perimeter of the integrated circuit die (16), the wire bonds (18), a portion of the leads (33), the perimeter portion of the back of the die (22), and the lead frame die mounting portion (32). The plastic material is formed so as to expose the active circuitry on the face of the die and a central portion on the back of the die.

Abstract: An electronic component (14) is soldered to a circuit carrying substrate (11) by a method that allows the component to remain in better contact with the flat solder pads of the substrate. The circuit carrying substrate (11) has a plurality of solder pads (12) disposed thereon, each pad consisting of a terminal portion (16), a solder reservoir portion (18), and a bridging portion (17). The terminal portion is connected to the reservoir portion by the bridging portion. The bridging portion is typically a necked down portion of the pad. The electronic component (14) has a plurality of solderable terminals (15) corresponding to the terminal portions (16) of the solder pads (12). Each of the solder pad reservoir portions are coated with a reservoir of solder (23). The amount of solder coated onto the reservoir portion is sufficient to provide a fillet between the component (14) and the solder pad terminal portion (16) during a subsequent heating step.

Abstract: A method of forming flat solder bumps (16 and 18) on contact areas (12 and 14) of a first side and second side of a printed circuit board (12, 14 and 10) comprises the steps of applying solder paste in a predetermined pattern and a predetermined thickness on the contact areas of the first side and the second side of the printed circuit board forming joint areas. Next, the solder paste is reflowed. Then, the solder joints on the first side are flattened (17). Before surface mounted components (20 and 26) are mounted on the printed circuit board, tack media (32) is dispensed onto the joint areas. Subsequently, the printed circuit boards is reflowed. Now the second side of the printed circuit board is flattened (19). As with the first side, tack media (34) is dispensed on the solder joints on the second side before surface mounted components (40 and 46) are mounted on the second side. Finally, the printed circuit board is reflowed again.

Abstract: A selectively releasing runner and substrate assembly 100 comprises a plurality of conductive runners 116 adhered to a substrate 112, a portion 118 of at least some of the conductive runners 116 have non-planar areas with the substrate 112. Additionally the portion 118 has a lower adhesion to the substrate for selectively releasing the conductive runner 118 from the substrate 112 when subjected to a predetermined stress.

Abstract: A solder paste is formulated by combining a solder paste vehicle, a resin, and solder alloy particles. The solder paste vehicle is made by combining mono and polyfunctional alcoholic solvents with a fluxing agent. The solder particles are first reacted with a formate ion produced by formic acid, formaldehyde, paraformaldehyde, or mixtures thereof, in order to create a metal-formate complex that functions as an oxygen scavenger on the surface of the solder alloy particles.

Abstract: A circuit component 100 or (200) comprising typically of a hollow body 101 (201) and a plurality of solderable terminations (102 and 103 (202 and 203) is being disclosed. Internal to said circuit component 100 (200) is a plurality of electrodes 104 and 106 (204 and 206). A filling point 108 (208) is provided so as to fill the volume of said circiut component (100 (200 ) with a specific compound 114 (214) having a desired electrical characteristics including dielectric constant. A method for manufacturing said circuit component 100 (200) is disclosed.

Abstract: A multilayer substrate having an integral transmission line structure 300 is disclosed. The transmission line structure 300 is formed by metallizing a fluroplastic substrate on the inner surface 112 and outer surface 114 in order to form a transmission line. The metallized inner surface forms a conductive runner 106, while the outer metallized surface 114 forms a ground plane, with the fluroplastic substrate being the dielectric. The transmission line structure 300 is then encapsulated by two substrate layers (402, 404).

Abstract: A manifold (10) for use in a gas solder-reflow oven (50) comprises a hollow tube made from a transition metal having an open end (18) for receiving gas, a closed end (16), and a plurality of holes (12).

Abstract: A method of forming solder bumps includes the steps of applying a thick layer of solder resist to a substrate. The resist is selectively removed to provide wells at solder pads on the substrate. The solder paste is applied to the substrate in the wells. The solder paste is reflowed to form solder bumps on the pads. A socket for a solder bumped member is obtained by first providing a substrate having metalized pads corresponding to the solder bumps of the member. A thick layer of photo definable solder resist is applied to the substrate. The resist is selectively removed to provide wells at the metalized pads of the substrate. Solder paste is then deposited in the wells. The solder bumped member can then be positioned so that the solder bumps are located in the wells. The solder paste is reflowed to bond to the solder bumps and the metalized pads. The solder paste can be selected to have a lower melting temperature than the solder bumps.

Abstract: Printed circuit patterns are photolithographically defined on a three dimensional "projection" surface (204) of a printed circuit substrate (202) using a projection image aligner and a photomask (210) having a planar image (210A). The geometry of the projection is restricted such that the slope of the projection surface, as measured at any point on the projection surface and relative to a reference plane which is parallel to the focal plane of the projection image aligner, is less than 90 degrees. A solution of photoresist includes a photoresist solvent, a fluorosurfactant and an aromatic hydrocarbon solvent, and is preferably sprayed over the projection surface. In one method of manufacture, the printed circuit substrate is moved from one position to another during the exposure of the photoresist layer (206). In another method, after a first portion of the projection surface is exposed by a first photomask (502), a second photomask (504) is substituted and the remainder of the projection surface exposed.

Abstract: A first conductive layer 12 is deposited on the substrate 14. Next, a second conductive layer 16 with a circuit pattern is deposited on the first layer 12. Finally, the first conductive layer 12 not residing under the second conductive layer 16 is etched off, leaving the second layer 16 above the first layer 12.

Abstract: Electrical interconnection of first and second sides of a flex circuit is provided by a tab formed in the flex circuit. At least one circuit trace extends along the tab and provides a contact area on the flex circuit first side. The tab is folded so that the contact area overlays the flex circuit second side. The contact area is then electrically interconnected as by reflow soldering to a contact area on the flex circuit second side.

Abstract: A pad grid array comprises an array of cavities (12) formed in a circuit carrying substrate (10) that are metallized (18, 20, and 22) to provide electrical conductivity. The metallized cavities are preferably hemispherical in shape and approximately the size of the solder bumps (30) coupled to a solder bumped chip carrier (28) that will be mounted thereon. Flux (26) is applied to each of the metallized cavities before positioning the solder bumped chip (28) carrier over the pad grid array. Proper mounting can be detected by tactile sensing in either human or robotic assemblers when the solder bumps "drop" into the metallized cavities.

Abstract: A molded thermoplastic housing (100) includes base (102) and cover (104) members joined by a living hinge (106). The base member (102) includes a peripheral wall (108). Four solderable printed circuit patterns (112, 114, 116 and 118) are vacuum deposited onto the interior and exterior surfaces of both housing members. The printed circuit patterns on opposing surfaces of the base and cover members are joined by conductive through-holes (e.g., 120 and 122), while the printed circuit patterns on the interior surfaces of the base and cover members are joined by an interconnecting printed circuit pattern (124) which is vacuum deposited onto the living hinge. Mylar sheets (132) are adhered to the exterior surface of the housing to insulate the exterior printed circuit patterns. An antenna pattern (126) is also vacuum deposited onto an exterior surface of the housing.

Abstract: The preferred housing includes an integrally molded thermoplastic base (102) and cover (104) assembly. The cover is joined to the base by a living hinge (106) and a peripheral wall (108) extends around the perimeter of the base. In one embodiment, the antenna is a wire loop (204), the wire being wound in an external circumferential groove (202A) in the peripheral wall or, alternatively, integrally molded into the peripheral wall. Other embodiments use printed circuit loop antenna patterns that are preferably vacuum deposited directly onto the thermoplastic base and/or cover. When the antenna pattern is disposed on both the cover and the base, a portion of the antenna (e.g., 1002K) is also disposed on the hinge to join the main portions of the antenna on the base and cover. In one embodiment of the printed circuit loop antenna, the plane of the loop lies parallel to the base and may include one or more turns or loops (e.g., 402C, E, G and J). In another embodiment, the loop includes a 90 degree bend (e.g.

Abstract: An adjustable thick film capacitor includes a conductive paste layer which is fired to form a first electrode on a substrate, at least one dielectric paste layer over the conductive electrode which is also fired, and an organo-metallic paste layer over the dielectric layer, which is fired at high temperature to form a very thin sintered metallic conductive layer for the second electrode. The organo-metallic paste includes molecules having conducting particles, such as gold atoms, which after firing form a residue layer having a thickness of the order of 1 micron. This thin electrode can be trimmed by an accurately controlled low energy laser beam to adjust the capacitor value.