Metal fusion bonding – Process – Plural joints
Reexamination Certificate
2001-11-13
2004-07-13
Edmondson, Lynne Renee (Department: 1725)
Metal fusion bonding
Process
Plural joints
C228S051000, C228S020500, C228S006100, C228S006200, C228S042000, C228S020100, C228S264000, C219S227000, C219S228000, C219S229000
Reexamination Certificate
active
06761304
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to soldering and desoldering of SMD components, and more specifically to a heating device having a novel hot gas flow arrangement, nozzle attachment mechanism, and end nozzle design for soldering and desoldering solid state devices through utilization of a stream of hot neutral gas.
2. Description of the Prior Art
The subject of this patent is a heating head for soldering and de-soldering of SMD components using a hot neutral gas or air stream.
Numerous hot gas type soldering/desoldering machines are known for attaching and removing electronic components from a printed circuit board (PCB). One known solution is described by Polish Patent (# Ru-54524), in which a heating nozzle placed at the end of a heating device for dispersing a hot gas (air) is comprised of a round shroud in the form of a sliced cone. Situated in the shroud on one side is a threaded hole, while on the other side there is a round plate in which two or four narrow elongated holes are situated, distributed in parallel to the shape of the square or rectangle, in the case of 2 holes, or two parallel pairs perpendicular one to each other in the case of 4 holes, and in the middle there is one round hole. Discharge nozzles are fastened in the elongated holes, which are equipped with protruding directional flaps or end fittings. In the above solution, the discharge nozzles have a different construction applicable to a different type of solid state devices.
Also known are other designs of heater end nozzles or end fittings, in which the discharge nozzles have a conical shape, flattened at the bottom, made of thin wall tubing formed by a complicated multitask method of plastic forming coupled with thermal forming. In this type of end fittings, good parameters of working gas are achieved. However, due to the complicated production process, they are expensive. Furthermore, the above-described solution applies to only one element of a heating head. End nozzles have the same cross-section on their entire lengths. The shape of the shroud and the end nozzles has a direct effect on the parameters of the hot gas (air). In the previous solutions, there is too big a difference between the temperature of the hot gas in the middle and at both ends of the end nozzles.
There are also known other configurations of nozzles in which the end nozzles have a conical shape and are flattened at the ends. Such nozzles are made of a thin wall tubing formed by a compacted, multitasking forming process including hot forming. In such nozzles, the parameters of the hot gas for soldering are good, but because of the nature of the nozzle production process, they are also very expensive.
Another solution is known from Polish patent # Ru-54524, in which the electrical heater is comprised of a cylindrical ceramic shroud. Such shroud is enclosed on both ends with perforated end cups having centrally located holes to mount to the heater core in a shape of a cylinder with a centrally located hole and additional holes on the perimeters for electrical wires. The shroud, end cups and heater rod are made of an insulative material such as ceramics or quartz glass, and the shroud is inside the cylindrical thin wall tube made of an insulation material such as mica. The above solution concerns another element of the heating head, and is the predecessor of the solution presented in this application. This predecessor does not have characteristics concerning construction of the entire heating head.
There are also known solutions for complete heating heads. They are comprised of the handle, heater assembly, fast connecting mechanism, and nozzle. However, the parts of such prior heating heads make the usefulness of a complete head less practical and useful. For example, electrical supply and control wires and air lines are attached to the handle at the end of the handle along the axis of the heating head. This causes cumbersome cable pull sideways during hand held operations. In addition, the heater is placed inside the handle, which often causes overheating and shortens life of the device.
Reference is also made to the following prior art patents:
U.S. Pat. No. 4,295,596 issued to B. O. Doten et al. on Oct. 20, 1981, entitled “METHODS AND APPARATUS FOR BONDING AN ARTICLE TO A METALLIZED SUBSTRATE,” discloses a hot gas type soldering/desoldering device wherein hot gas can be directed substantially parallel to the surface of a printed circuit board by angled deflectors on the end of the heater nozzle. Doten et al. is illustrative of the fact that many early prior art nozzles were held to the heater body by bolts and therefore could not be quickly attached or removed therefrom.
U.S. Pat. No. 4,564,135 issued to A. J. Barresi et al. on Jan. 14, 1986, entitled “CHIP CARRIER SOLDERING TOOL,” discloses a nozzle for soldering/desoldering electronic components which diverts most of the hot gas flow to the periphery of the component, although not in the same manner as the present invention.
U.S. Pat. No. 4,767,047 issued to R. I. Todd et al. on Aug. 30, 1988, entitled “DESOLDERING DEVICE,” discloses a hot gas type desoldering device having a suction device for lifting a circuit from a circuit board. However, such solution discloses none of the specific improvements of the present invention.
U.S. Pat. No. 4,787,548 issued to L. A. Abbagnaro et al. on Nov. 29, 1988, entitled “NOZZLE STRUCTURE FOR SOLDERING AND DESOLDERING,” discloses an adjustably positionable nozzle for a soldering/desoldering tool having a means for uniformly distributing heated air through the nozzle. However, such reference teaches a different nozzle structure, and the nozzles are attached to the soldering device by holes or bores which receive screws, which task is time consuming and inconvenient. Also see U.S. Pat. Nos. 4,899,920 and 4,972,990 issued to Abagnaro et al.
U.S. Pat. No. 4,805,827 issued to B. W. Coffman et al. on Feb. 21, 1989, entitled “METHOD OF SOLDERING WITH HEATED FLUID AND DEVICE THEREFOR,” discloses a nozzle for a hot gas soldering device having a horizontal baffle member which directs the gas laterally to the sides of the nozzle, and then downwardly to the sides of an electronic component. While laterally deflecting the gas while in the nozzle apparently mixes the air so that when it is directed across the component it has a more uniform temperature, such solution does not increase the uniformity of the gas flow from the heater head through the nozzle and across the electronic component as in the present system.
U.S. Pat. No. 4,858,820 issued to G. M. Kent on Aug. 22, 1989, entitled “DESOLDERING AID AND METHOD,” discloses a cap-like nozzle desoldering attachment. The Kent nozzle is primarily designed to desolder older electronic components wherein the leads extend from the sides of the component, rather than the more modern BGA type components.
U.S. Pat. No. 5,380,982 issued to W. S. Fortune on Jan. 10, 1995, entitled “METALLIC CONDUCTION—HOT GAS SOLDERING—DESOLDERING SYSTEM,” discloses a hot air type system which can be used with a tip designed for desoldering an SMD device. However, Fortune does not teach a suction cup on the end of the vacuum tube or a nozzle structure for uniformly distributing such hot air.
U.S. Pat. No. 5,419,481 issued to C. S. Lasto et al. on May 30, 1995, entitled “PROCESS AND APPARATUS FOR ATTACHING/DETACHING LAND GRID ARRAY COMPONENTS,” discloses another soldering/desoldering nozzle for BGA, as well as SGA and CGA type electronic components. While the gas flow inlet and exhaust flow patterns created by the nozzle result in a continuous flow and apparently more uniform solder melting, Lasto et al. does not attempt to provide a more uniform flow through the heater head as in the present invention.
U.S. Pat. No. 5,579,979 issued to G. Kurpiela on Dec. 3, 1996, entitled “SOLDERING/DESOLDERING NOZZLES FOP SMD'S,” discloses an improved heating nozzle having slotlike recesses along its bottom periphery through which hot gas is directed at the leads of an el
Edmondson Lynne Renee
Wilkinson Charles A.
Wilkinson Clinton H.
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