Patents by Inventor Curtis W. Mitchell

Curtis W. Mitchell has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Silver flashing process on semiconductor leadframes
    Patent number: 4883774
    Abstract: A process for flashing a thin layer of silver on metal leadframes using no mask steps and a minimal amount of silver. An unmasked metal leadframe is placed into a cleaning bath that includes silver in solution and has no outside electrical driving force to assist plating. The leadframe is removed from the cleaning bath once a uniform silver layer having a thickness of 100 to 1000 angstroms is plated thereon. The silver layer need not be exact and, therefore, it is not critical that the period of time the leadframe remains in the cleaning bath be exact.
    Type: Grant
    Filed: March 21, 1988
    Date of Patent: November 28, 1989
    Assignee: Motorola, Inc.
    Inventors: Frank Djennas, Curtis W. Mitchell
  • Gold metallization process
    Patent number: 4702941
    Abstract: A one step metallization is disclosed for applying a layer of gold or gold alloy to the back of a silicon substrate to facilitate bonding that substrate to a metallized package member. The gold is applied to the substrate, for example by evaporation, while the substrate is maintained at a temperature between about 200.degree. C. and about 360.degree. C. Following the deposition the substrate is quickly cooled to room temperature. The thickness of the gold layer and the deposition temperature are adjusted to insure that the silicon diffusion profile is contained within the gold film during deposition. This insures good adhesion of the gold to the silicon substrate and provides a pure gold surface layer necessary for optimum bonding of the semiconductor substrate to a metallized package portion.
    Type: Grant
    Filed: March 27, 1984
    Date of Patent: October 27, 1987
    Assignee: Motorola Inc.
    Inventors: Curtis W. Mitchell, Barry C. Johnson
  • Fiber optics semiconductor package
    Patent number: 4653847
    Abstract: A semiconductor package for use in fiber optics systems is disclosed wherein optical performance is enhanced by a lens between a fiber segment and the photoactive area of the semiconductor. The lens is spaced a predetermined distance from the fiber by a layer of elastomer. During assembly of the package, the fiber provides a convenient means for handling the lens.
    Type: Grant
    Filed: February 23, 1981
    Date of Patent: March 31, 1987
    Assignee: Motorola, Inc.
    Inventors: Howard M. Berg, Curtis W. Mitchell
  • LED having self-aligned lens
    Patent number: 4501637
    Abstract: A relatively thick ring of polymer or metal encircles the emitting area of a light emitting diode. A spherical lens rests on the ring and is both accurately located with respect to and spaced from the emitting area.
    Type: Grant
    Filed: January 26, 1984
    Date of Patent: February 26, 1985
    Assignee: Motorola, Inc.
    Inventors: Curtis W. Mitchell, Howard M. Berg
  • Low thermal impedance plastic package
    Patent number: 4399453
    Abstract: A package for fiber optic semiconductor devices is disclosed in which heat is conducted by both a heat spreader and through a plastic enclosure portion of the package.
    Type: Grant
    Filed: March 23, 1981
    Date of Patent: August 16, 1983
    Assignee: Motorola, Inc.
    Inventors: Howard M. Berg, Gary L. Lewis, Curtis W. Mitchell