Composite coatings for thermal properties

Details Composite coatings for thermal properties Composite coatings for thermal properties

1999-08-02

2001-10-30

Tentoni, Leo B. (Department: 1732)

Plastic and nonmetallic article shaping or treating: processes

Direct application of electrical or wave energy to work

Forming articles by uniting randomly associated particles

C264S114000, C264S125000, C264S127000, C427S180000, C427S304000, C427S305000, C427S437000

Reexamination Certificate

active

06309583

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to processes for the formation of composite layers containing insoluble particles in metal matrices onto bodies to achieve enhanced thermal properties.
Countless applications in a wide array of industries require enhanced thermal properties including conduction and insulation. Deliberate material selection for these properties has been practiced throughout human history. When the use of a single material is not practical to achieve certain desired thermal properties, the use of coatings or composites is a widely accepted alternative. There are a vast number of coating methods to achieve enhanced thermal properties. This invention relates to processes for the formation of composite layers containing insoluble particles in metal matrices onto bodies to achieve enhanced thermal properties.
SUMMARY OF THE INVENTION
Composite plating is a technology well documented and widely practiced in both electrolytic and electroless plating. The development and acceptance of composite plating stems from the discovery that the inclusion of particles within a plated layer can enhance various properties of the plated layer, and in many situations actually provide entirely new properties to the plated layer. Particles of various materials can provide characteristics including thermal properties, wear resistance, lubricity, corrosion resistance, phosphorescence, friction, light absorption, altered appearance, and others. See
FIG. 1
which shows a typical cross sectional view of a composite layer of particles (
1
) in a metal matrix (
2
) on a body (
3
).
Although composite electrolytic plating predates composite electroless plating, composite electroless plating has been developed into a well established field. A well documented survey of composite electroless plating can be found in “Electroless Plating Fundamentals and Applications” edited by G. Mallory and J. B. Hadju, Chapter 11, published by the American Electroplaters Society, 1990.
Early development of composite electroless plating includes the work of Odekeren in U.S. Pat. No. 3,644,183 which was directed toward increasing the corrosion resistance by the incorporation of certain particulate material. Metzger et al documented a wider variety of plated alloys and particulate materials capable of being composite plated in U.S. Pat. No. 3,753,667. In U.S. Pat. Nos. 3,562,000 and 3,723,078, Parker further demonstrated an assortment of materials including metallic particles which can be codeposited from an electroless plating bath.
In U.S. Pat. No. 3,853,094, Christini et al disclosed an electroless plating apparatus which serves to insure the uniformity of particulate dispersion within a composite electroless plated layer. Subsequent work by Christini et al in U.S. Pat. Nos. 3,936,577 and 3,940,512, and Reissue Pat. Nos. 29,285 and 33,767 concentrated on the codeposition of diamond particles within electroless plating.
Additional inventions in the field of composite electroless plating include the use of a wider array of particulate materials such as Yano et al in U.S. Pat. No. 4,666,786 and Henry et al in U.S. Pat. No. 4,830,889.
Spencer et al illustrated the benefit of including a blend of distinct particle sizes within the composite plated layer.
Feldstein et al disclosed plating bath stability benefits resulting from the addition of particulate matter stabilizers to the plating bath in U.S. Pat. Nos. 4,997,686, 5,145,517, 5,300,330, and 5,863,616.
Material selection for thermal properties has been widely practiced throughout history. Certain ceramic materials, plastics, and textiles are widely utilized for their thermal insulating abilities. Common examples of such applications include Styrofoam cups and fiberglass insulation. A number of methods have been developed to apply heat insulating materials to various articles including the employment of composite electrolytic plating. One such example can be found in U.S. Pat. No. 5,103,637 by Itoh et al where heat insulating particles such as zirconia, yttria, ceria, silica, alumina, titania, and mullite are codeposited within an electrolytic plated metal matrix.
Materials such as copper, silver, aluminum, and diamond are well known for their excellent thermal conductivity properties. Examples include copper bottoms of cookware, radiator cores, and copper heat sinks used in electronic applications. Heat transfer in electronic applications is a field which has generated much commercial interest and research and development. Heat sinks are a primary area of interest for these properties in this field.
To employ the properties of diamond for instance, a wide array of methods have been developed to produce an article comprised of or coated with diamond such as microwave chemical vapor deposition (CVD), thermal filament CVD, high frequency CVD, electron cyclotron resonance microwave CVD, direct current plasma CVD, ion plating physical vapor deposition (PVD), ion beam sputtering PVD, ion deposition PVD, ion beam deposition PVD, composite electrolytic plating, and others. Poor adhesion, brittleness, nonuniformity, substrate incompatibility, geometry constraints, thickness restrictions, and cost of these diamond, diamond containing, or diamond like films to substrates have traditionally been limited to these methods in many applications. Many procedures have been developed with varying degrees of success to overcome these limitations. In U.S. Pat. No. 5,824,367, Park et al. discusses the improved adhesion such diamond films onto substrates that have previously been electrolessly nickel plated.
Industries concerned with heat transfer have pursued the use of diamond for improved heat transfer. Heat sinks which exist in a variety of sizes and types for electronic and other applications are a prime example. See
FIG. 2
of a typical heat sink. Specific examples include U.S. Pat. No. 5,791,045 wherein Yamamoto disclosed a method for manufacturing diamond heat sinks by inserting diamond or polycrystalline cubic boron nitride into gaps in a base material, growing diamond on the surface of this unit, and then removing the base material. Hirabayashi taught another method of producing a diamond covered member for heat sinks and other applications in U.S. Pat. No. 5,807,432.
Because the use of certain theoretically ideal materials is often not possible for a number of reasons including physical limitations and economic factors; efforts have been made in the past to produce composites of two or more materials that are physically possible, practical, economic, and effective for the desired thermal characteristics. In U.S. Pat. No. 5,783,316, Colella et al. describe a composite of diamond particles compacted into a porous body and infiltrating the porous body with a brazeable material such as copper-silver. Other prior art involved with hot pressing diamond-metal compacts include Vereschagin's U.S. Pat. No. 3,912,500, Burnham's U.S. Pat. Nos. 5,008,737 and 5,130,771, and Supan's U.S. Pat. No. 5,120,495.
Despite these efforts, the utilization of certain materials with desirable heat transfer properties is still not possible or practical in many applications. This invention relates to processes for the formation of composite layers containing insoluble particles in metal matrices onto bodies to achieve enhanced thermal properties.
DETAILED DESCRIPTION OF THE INVENTION
More specifically this invention relates to the codeposition of particles of materials with desirable heat transfer properties within an electroless metal or alloy plated matrix. This invention extends the properties of the particulate matter to the article in a method compatible with a very wide array of substrates of nearly any geometry, and at a practical cost compared to many more involved deposition processes.
Further included in this invention is the process of coating a body possessing a specific geometry by the processes disclosed herein and subsequently removing the substrate from the coated layer by mechanical or chemical means to leave a composite structure with properties usef

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