Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K9/00—Screening of apparatus or components against electric or magnetic fields
  • H05K9/0073—Shielding materials
  • H05K9/0075—Magnetic shielding materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/18—Non-metallic particles coated with metal
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K9/00—Screening of apparatus or components against electric or magnetic fields
  • H05K9/0073—Shielding materials
  • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
  • H05K9/0083—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive non-fibrous particles embedded in an electrically insulating supporting structure, e.g. powder, flakes, whiskers
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K9/00—Screening of apparatus or components against electric or magnetic fields
  • H05K9/0073—Shielding materials
  • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
  • H05K9/0084—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising a single continuous metallic layer on an electrically insulating supporting structure, e.g. metal foil, film, plating coating, electro-deposition, vapour-deposition

Definitions

• Example embodiments generally relate to electrically conductive fillers having corrosion resistance.
• example embodiments relate to nickel coated graphite (Ni/C) that is coated with nickel chromium (NiCr) which has a high resistance to oxidation and corrosion.
• EMI electromagnetic interference
• electrically conductive materials can be used to shield EMI.
• Conventional shields to reduce EMI can be constructed by conductive materials having silver coated powders (Ag/Cu, Ag/Al, Ag/glass) or Ni coated powders. These shields may be effective to reduce EMI, silver has limited corrosion resistance.
• Example embodiments of the present disclosure relate to an electrically conductive composite powder for improving EMI shielding performance.
• the electrically conductive composite powder includes a core of particles; a nickel layer coated onto the core of particles; and a corrosion resistant alloy layer that is deposited onto the nickel layer.
• Preferred embodiments of the present disclosure relate to a nickel coated graphite (Ni/C) based electrically conductive filler in which a nickel coating layer is coated with nickel chromium (NiCr).
• the corrosion resistance of nickel is improved by adding chromium.
• the nickel chromium (NiCr) layer exhibits a high resistance to oxidation and improves the corrosion properties of the Ni/C based electrically conductive filler.
• a powder of the Ni/C based electrically conductive filler may be produced with a density that is 30%.
• the Ni/C based electrically conductive filler includes a graphite core of particles, a nickel layer coated onto the graphite core of particles, and a nickel chromium (Ni/Cr) layer that is coated onto the nickel layer.
• Ni/Cr nickel chromium
• at least one layer of nickel, which acts as a corrosion resistant layer, can be added in the Ni/C based electrically conductive filler.
• Ni/C based electrically conductive filler of the present disclosure addresses problems, including high cost, of conventional Ag/glass shields.
• FIG. 1 illustrates a cross section of an electrically conductive filler, according to various embodiments.
• FIG. 1 illustrates a cross section of an electrically conductive filler 100, according to various embodiments.
• the electrically conductive filler 100 includes a core of particles 110, a nickel layer 120 coated onto the core of particles 110, and a corrosion resistant alloy layer 130 that is deposited onto the nickel layer 120.
• the electrically conductive filler 110 is embedded in a resin.
• Ni/Cu/C is loaded in silicon rubber in a 60/30 ratio by weight to produce conductive adhesives or extruded gaskets, which will provide shielding performance > 100 db in the 40-
• the core of particles 110 is formed using a material having a low density, a high dielectric constant, and a low electrical resistance.
• the core of particles 110 is formed using a material having a low density for the final composite particles to match the density of the resin.
• the density of the material used for the core of particles 110 is 5 g / cm 3 or less.
• the density of the material used for the core of particles 110 is less than 3 g/cm 3 .
• the density of the material used for the core of particles 110 is less than 2.5 g/cm 3 .
• materials suitable for the core of particles in this disclosure include, but are not limited, to graphite having a density of 2.266 g/cm 3 , silica having a density of 3.21 g/cm 3 , and titanium dioxide having a density of 4.23 g/cm 3 .
• the core of particles 110 has a high dielectric constant of > 10 which increases the shielding effectiveness of the core by enhancing the reflection of incident electromagnetic waves.
• the dielectric constant is a dimensionless property and defined as the ratio of the electric permeability of the material to the electric permeability in a vacuum.
• the dielectric constant of the core of particles 110 is 2 or greater.
• the dielectric constant of the core of particles 110 is 10 or greater.
• the dielectric constant of the core of particles 110 is 100 or greater.
• Exemplary examples of core of particles 110 include graphite having a dielectric constant of 10-15, titanium dioxide having a dielectric constant of 80-100, and silicon carbide having a dielectric constant of up to 10.
• the core of particles 110 have a low electrical resistance by enhancing the adsorption of incident electromagnetic waves by the core material.
• the core of particles 110 have an electrical resistivity at or below 10 Ohm*m.
• Graphite, titanium dioxide, and silicon carbide each has an electrical resistivity in the range of about 5xl0 -4 to 10 Ohm*m.
• the electrically conductive filler 100 can be manufactured by coating the core of particles
• the coating core of particles 110 have an average particle diameter (D50) of 0.05-100 pm with metallic nickel using, for example, plating, autoclave, or gas-phase technology.
• the coating core of particles 110 have an average particle diameter (D50) of .05-100 pm.
• the nickel layer 120 has a thickness of 0.1 to 4 pm. In embodiments, the nickel layer 120 has a preferable thickness of 1 to 2 pm.
• the corrosion resistant alloy layer 130 is coated onto the nickel layer 120 via Physical Vapor Deposition (PVD), Metal-Organic Chemical Vapor Deposition (MOCVD), plating or autoclave methods.
• PVD Physical Vapor Deposition
• MOCVD Metal-Organic Chemical Vapor Deposition
• the corrosion resistant alloy layer 130 is formed onto the nickel layer 120 by converting part of the nickel layer 120 into the corrosion resistant alloy layer 130.
• a relatively thin corrosion resistant alloy layer 130 is deposited onto the nickel layer 120 to further improve corrosion resistance.
• the corrosion resistant alloy layer 130 is deposited as the outer layer having a more noble galvanic potential in seawater than nickel as measured via ASTM G82.
• the electrochemical potential of the corrosion resistant alloy layer 130 is -0.2 V as compared to Ag/AgCl reference or greater. In some embodiments, the electrochemical potential of the alloy is -0.1 V as compared to Ag/AgCl reference or greater.
• Some non-limiting alloys of materials which can be used for the corrosion resistant layer 130 include, but are not limited to, Nickel-Chromium alloys and Nickel Copper alloys.
• Example embodiments of Nickel Copper alloys include Monels, Nickel 600 series alloys, stainless steels, and superalloys.
• Example embodiments of superalloys include Hastelloys, Inconels, and Tungsten.
• the corrosion resistant layer 130 is formed via the pack diffusion process.
• a nickel chromium layer is formed by chromium pack diffusion into the nickel layer 120.
• a nickel copper layer can be formed with copper pack diffusion into the nickel layer 120.
• the corrosion resistant layer 130 is a relatively thin nickel-chromium (NiCr) layer in a range of 100 nm to 500 nm that is formed via pack diffusion of chromium into the nickel layer 120.
• NiCr nickel-chromium
• enhanced corrosion resistance is provided to the electrically conductive filler 100 without the use of known corrosion resistant elements which are expensive.
• the use of silver is specifically avoided.
• gold is specifically avoided.
• platinum is specifically avoided.

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• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Laminated Bodies (AREA)
• Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
• Conductive Materials (AREA)
• Powder Metallurgy (AREA)

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• 2021
  • 2021-12-03 KR KR1020237007983A patent/KR20230113275A/ko not_active Ceased
  • 2021-12-03 JP JP2023533994A patent/JP2023552209A/ja active Pending
  • 2021-12-03 US US18/027,533 patent/US20230380121A1/en active Pending
  • 2021-12-03 EP EP21901536.9A patent/EP4255998A4/en active Pending
  • 2021-12-03 WO PCT/US2021/061833 patent/WO2022120186A1/en not_active Ceased

Patent Citations (4)

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