WO1998020719A1 - Materiaux pour blindage contre les interferences hautes frequences/electromagnetiques - Google Patents

Materiaux pour blindage contre les interferences hautes frequences/electromagnetiques Download PDF

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Publication number
WO1998020719A1
WO1998020719A1 PCT/US1997/020746 US9720746W WO9820719A1 WO 1998020719 A1 WO1998020719 A1 WO 1998020719A1 US 9720746 W US9720746 W US 9720746W WO 9820719 A1 WO9820719 A1 WO 9820719A1
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WO
WIPO (PCT)
Prior art keywords
polymer
composition
particulate material
electrical conductivity
article
Prior art date
Application number
PCT/US1997/020746
Other languages
English (en)
Inventor
Robert W. Vandine
George F. Johnson
Robert Langton
Original Assignee
The Jpm Company, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by The Jpm Company, Inc. filed Critical The Jpm Company, Inc.
Priority to AU51792/98A priority Critical patent/AU5179298A/en
Publication of WO1998020719A1 publication Critical patent/WO1998020719A1/fr

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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
    • H05K9/0081—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
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys

Definitions

  • This invention relates to materials useful in electronic devices, and particularly to plastic materials which are effective to provide radio frequency/electromagnetic interference shielding.
  • Plastic materials are routinely employed in the electronics industry in many diverse applications, some examples of which include, without limitation, cables, connectors, peripherals, and wired/wireless (cellular) networks in communication equipment and computers, navigational equipment, consumer/ industrial medical applications, audio/video products, appliances, lighting, power generation and distribution applications, buildings, and various electrical components in vehicles.
  • plastic materials are used which are effective to shield such equipment from radio frequency/electromagnetic interference ("RFI/EMI").
  • RFID/EMI radio frequency/electromagnetic interference
  • finely divided conductive substances are dispersed in plastic to provide a conductive composite material effective to provide RFI/EMI shielding. Such substances have included carbon, silver and aluminum flakes.
  • U.S. Patent No. 4,963,291 to Bercaw discloses electromagnetic shielding resins which comprise electroconductive particles, such as iron, aluminum, copper, silver and steel in sizes ranging from 0.5 to 50 ⁇ m in spherical cross-section, and electrically non-conductive particles, such as mica, quartz, glass, aluminum silicate and alumina in sizes ranging from 0.005 to 2 ⁇ m in diameter.
  • electroconductive particles such as iron, aluminum, copper, silver and steel in sizes ranging from 0.5 to 50 ⁇ m in spherical cross-section
  • electrically non-conductive particles such as mica, quartz, glass, aluminum silicate and alumina in sizes ranging from 0.005 to 2 ⁇ m in diameter.
  • Other examples include U.S. Patent No. 4,695,404 to Kwong, which discloses a polymeric composition comprising a polymeric binder and a silver powder comprising particles and/or flakes having a diameter of from about 0.1 to 44 ⁇ m; U.S. Patent No.
  • conductive polymer compositions comprising a polymeric material in which is dispersed conductive metal particles which have a preferred particle size of about 0.01 to about 200 ⁇ m, along with a particulate filler; and U.S. Patent No. 4,407,624 to Ehrreich which provides an organic resin matrix in which is incorporated silver flake-shaped particles 0.1 ⁇ m thick or less .
  • compositions may provide the requisite RFI/EMI shielding, they are difficult and expensive to manu- facture due to high viscosities encountered upon the combination of polymeric and relatively large sized particulate matter.
  • the present invention overcomes the above-identified problems by providing a novel and improved RFI/EMI shielding composition and process for its production which utilizes metallic conductive particulate materials in a size range heretofore not known and/or contemplated in electrical systems and electrical components, and which are easily dispersed in polymeric materials such as plastic.
  • the present invention provides a composition
  • a composition comprising a polymer and metal particulate material ranging in size from about lOnm to about lOO ⁇ m in length and preferably from about l ⁇ m to about lOO ⁇ m in length, wherein said composition has an electrical conductivity effective to provide FRI/EMI shielding.
  • FIG. 1 graphically illustrates specific electrical resistivity (DC) of a composition of the present invention which comprises silver nano-size powder and silver flakes in an epoxy matrix as a function of silver volume percent content .
  • FIG. 2 is perspective drawing of a conventional cable connection endpoint assembly.
  • FIG. 3 is a drawing of a cable connector endpoint assembly manufactured from a composition of the invention.
  • Radio frequency/electromagnetic interference is the impairment of the performance of an electrical system or component and the like by unwanted electromagnetic disturbances .
  • the present inventive compositions comprise a polymeric material and nanometer-size particulate material in which the composition has an electrical conductivity effective to provide shielding against such interference.
  • Noise or interference is often introduced into, for example, circuits by extraneous voltage signals coupled into the circuit from the surroundings .
  • the most common sources of noise comes from the 60 Hz electromagnetic fields (EMI) produced by power mains and from 10 E+3 Hz to 10 E+9 Hz "radio" fields (RFI) produced by many electronic circuits.
  • the voltage signals induced by low frequency EMI fields is called "hum" since it is audible as low frequency tones in amplifiers connected to loud speakers .
  • Other stray voltage pickup may result from electric fields generated by nearby electronic devices and equipment, electric motors, lightning and electrostatic discharges, etc. It is desirable to shield those portions of a circuit where the actual voltage signal is small and consequently where the noise voltages are the most troublesome.
  • the electric fields induce stray voltages capacitively.
  • the magnetic fields induce stray voltages inductively.
  • Such shielding is also effective in reducing so-called "cross-talk" between two different stages or portions of the same component such as a circuit or cable connector assembly.
  • skin depth For electromagnetic waves with frequency (f) less than 10E+14 Hz (below the optical range of the spectrum) , the "skin depth" of "metallic- like" materials is given by the equation:
  • Silver has an electrical conductivity of 3 x 10 E+5 inverse ohm-cm at a common microwave frequency (lOE+10 Hz) .
  • the skin depth of silver in this case is 9.2 x 10E-5 cm.
  • silver plating is therefore used to reduce the material cost of high-quality waveguide components for microwave ovens and waveguide components.
  • the skin depth of silver is about 0.836 cm. In copper, the skin depth is 0.850 cm, at 60 Hz low frequency, but the skin depth is 0.71 x 10D-3 cm at the radio frequency of 10E+8 Hz.
  • Table I provides the number of skin depths (N) effective to produce a given stray or interference voltage reduction in number of dB down (dB is log base 10).
  • the term "length" is preferred for use in describing nanoparticles useful in the present invention.
  • the electrical conductivity-enhancing volume concentrations are effectively low such that thermal conductivity and dynamic viscosity/rheology of polymeric materials are negligibly affected, while electrical conductivity is increased by several orders of magnitude, all of which provides a great advantage over conventional materials in terms of ease of manufacturing and manufacturing costs .
  • the addition of metallic particulate material (about 5 ⁇ m to about lO ⁇ m in length) to insulating polymer (epoxy) in a preferred volume percent (from about 2 volume percent to about 15 volume percent, as discussed below) greatly increases the electrical conductivity of the polymer at volume concentrations of at least one-fourth that of conventional size micropowders and flakes, or less than five volume percent versus more than twenty volume percent .
  • volume concentrations of the electrical conductivity-enhancing nanoparticles are maintained such that the thermal conductivity and dynamic viscosity/rheology of the insulating polymer are negligibly affected while electrical conductivity is increased, preferably by several orders of magnitude.
  • Nanoparticle loading in the compositions of this invention preferably range from about 0.10% volume to about 50% volume or greater, depending upon the end use contemplated, are more preferably within the range of from about 2 to about 15 volume percent .
  • Polymeric materials useful in this invention include any material useful in the electronics industry, including, without limitation, thermoplastics (crystalline or non- crystalline, cross-linked or non-cross-linked) , thermosetting resins, elastomers or blends or composites thereof.
  • thermoplastic polymers include, without limitation, polyolefins, such as polyethylene or polypropylene, copolymers (including terpolymers, etc.) of olefins such as ethylene and propylene, with each other and with other monomers such as vinyl esters, acids or esters of ⁇ , ⁇ -unsaturated organic acids or mixtures thereof, halogenated vinyl or vinylidene polymers such as polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyvinylidene fluoride and copolymers of these monomers with each other or with other unsaturated monomers, polyesters, such as poly (hexamethylene adipate or sebacate) , poly (ethylene terephthalate) and poly ( tetramethylene terephthalate) , polyamides such as Nylon-6, Nylon-6, 6, Nylon- 6,10, Versamids, polystyrene, polyacrylonitrile, thermoplastic polymers, poly(
  • elastomeric resins examples include, without limitation, rubbers, elastomeric gums and thermoplastic elastomers.
  • elastomeric gum refers to polymers which are noncrystalline and which exhibit after cross-linking rubbery or elastomeric characteristics.
  • thermoplastic elastomer refers to materials which exhibit, in various temperature ranges, at least some elastomer properties. Such materials generally contain thermoplastic and elastomeric moieties.
  • the elastomer resin can be cross-linked or non cross-linked when used in the inventive compositions.
  • Illustrative examples of some suitable elastomeric gums for use in this invention include, without limitation, polyisoprene (both natural and synthetic) , ethylene-propylene random copolymers, poly (isobutylene) , styrene-butadiene random copolymer rubbers, styrene-acrylonitrile-butadiene terpolymer rubbers with and without added copolymerized amounts of ⁇ , ⁇ - unsaturated carboxylic acids, polyacrylate rubbers, polyurethane gums, random copolymers of vinylidene fluoride and, for example, hexafluoropropylene, polychloroprene, chlorinated polyethylene, chlorosulphonated polyethylene, polyethers, plasticized poly(vinyl chloride), substantially non-crystalline random co- or ter-polymers of ethylene with vinyl esters or acids and esters of ⁇ , ⁇ -unsaturated acids, silicone gums and base polymers,
  • thermoplastic elastomers suitable for use in the invention include, without limitation, graft and block copolymers, such as random copolymers of ethylene and propylene grafted with polyethylene or polypropylene side chains, and block copolymers of ⁇ - olefins such as polyethylene or polypropylene with ethylene/propylene or ethylene/propylene/diene rubbers, polystyrene with polybutadiene, polystyrene with polyisoprene, polystyrene with ethylene-propylene rubber, poly (vinyleyelohexane) with ethylene-propylene rubber, poly( ⁇ - methylstyrene) with polysiloxanes, polycarbonates with polysiloxanes, poly ( tetramethylene terephthalate) with poly ( tetramethylene oxide) and thermoplastic polyurethane rubbers .
  • graft and block copolymers such as random copolymers of ethylene and
  • thermosetting resins useful herein include, without limitation, epoxy resins, such as resins made from epichlorohydrin and bisphenol A or epichlorohydrin and aliphatic polyols, such as glycerol, and which can be conventionally cured using amine or amide curing agents.
  • epoxy resins such as resins made from epichlorohydrin and bisphenol A or epichlorohydrin and aliphatic polyols, such as glycerol
  • Other examples include phenolic resins obtained by condensing a phenol with an aldehyde, e.g., phenol-formaldehyde resin.
  • Other additives can also be present in the composition, including for example fillers, pigments, antioxidants, fire retardants, cross-linking agents, adjuvants and the like.
  • Conductive nanoparticles useful herein can be of virtually any metal effective to increase conductivity of a polymeric material in which it is incorporated, including without limitation, silver, copper, gold, iron, platinum, palladium, tantalum, nickel, tungsten, molybdenum, aluminum, zinc, cobalt, chromium, lead, titanium and tin.
  • Conductive particles of an alloy such as silver/copper, nichrome or brass, may also be employed.
  • the employ of conductive particle sizes much above about lOO ⁇ m in length will diminish provision of the aforementioned advantages of the invention of low volume loading coupled with highly increased electrical conductivity with a concomitant negligible change in polymeric thermal conductivity and dynamic viscosity/rheology.
  • the nanoparticles are preferably spherically shaped, but may also include any other shape such as flakes, rods and the like, and may be obtained from any commercial source, such as for example, Fraunhofer Institute, Bremen, Germany and the Vacuum Metallurgical Company in Japan.
  • composition of the present invention can be prepared by any conventional technique and can be employed, for example, as encapsulating and/or structural polymers for such components as electronic circuits, cables and connector assemblies.
  • inventive compositions can be prepared by melt blending the polymeric material and nanoparticles and other additives if desired in a conventional two or three roll mill, or in a Brabender or Banbury mixer, or by using mechanical stirring depending whether the polymer (s) employed is in liquid form at room temperature. High intensity ultrasonic mixers or high shear stirrers may also be used.
  • conductive and particulate filler are incorporated into thermosetting resins prior to cure.
  • thermosetting resins which are liquid at room temperature are employed which facilitate easy mixing with conductive particles.
  • Conductive compositions of thermosetting resins which are solids at room temperature can be easily prepared using conventional solution techniques.
  • the nanoparticles are homogeneously dispersed throughout the polymeric material employed. It is further preferred that nanoparticles be dispersed throughout the polymer matrix to eliminate any residual open and closed pore volume within the dispersed metal nanoparticles, to minimize the resistivity gap such as illustrated in FIG. 1.
  • compositions of the present invention are useful in providing RFI/EMI shielding in a variety of electronic components, such as, for example, circuits, devices, cable connectors, end-point assemblies and the like.
  • the illustrations in FIGS. 2 and 3 show respective cable end-point assembly housings of a design manufactured in a conventional manner and an assembly housing manufactured from the presently inventive composition, respectively.
  • the assembly in a conventionally obtained assembly for RFI/EMI shielding, the assembly includes PVC housing 2a with copper foil wrapped around terminal 2b containing several individually terminated copper wires encapsulated by a polymer adhesive, such as nylon 2c.
  • the copper foil is anchored mechanically and electrically to ground via solder 2d at necessary locations.
  • FIG. 3 illustrates a cable end-point assembly utilizing the presently inventive composition which includes housing 3a made of, for example, PVC.
  • a second layer for example, Nylon 3b, contains nanoparticles, such as, for example, silver, are preferably incorporated into the polymeric material to completely surround the original polyamide encapsulant thereby providing RFI/EMI shielding to he entire termination structure.
  • the inventive RFI/EMI shielding polymeric layer 3b can be electrically grounded at necessary locations.

Abstract

La présente invention concerne une composition de blindage contre les interférences hautes fréquences/électromagnétiques, contenant un polymère, et une quantité efficace d'un matériau constitué de particules métalliques d'une longueur comprise entre 10 nm et 100 νm environ, incorporé dans ledit polymère. La figure présente un exemple de connecteur contenant ladite composition de blindage.
PCT/US1997/020746 1996-11-07 1997-11-07 Materiaux pour blindage contre les interferences hautes frequences/electromagnetiques WO1998020719A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU51792/98A AU5179298A (en) 1996-11-07 1997-11-07 Materials for radio frequency/electromagnetic interference shielding

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US3078896P 1996-11-07 1996-11-07
US60/030,788 1996-11-07

Publications (1)

Publication Number Publication Date
WO1998020719A1 true WO1998020719A1 (fr) 1998-05-14

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000052710A1 (fr) * 1999-03-04 2000-09-08 Premix Oy Elastomere thermoplastique electroconducteur et produit en etant fait
WO2001041516A1 (fr) * 1999-11-30 2001-06-07 Welch Allyn Data Collection, Inc. Systeme d'instrument resistant aux charges electrostatiques
EP1991365A2 (fr) * 2006-02-08 2008-11-19 Acrymed, Inc. Procedes et compositions destines a des surfaces traitees avec des nanoparticules metalliques
US8900624B2 (en) 2004-07-30 2014-12-02 Kimberly-Clark Worldwide, Inc. Antimicrobial silver compositions
US9289378B2 (en) 2004-09-20 2016-03-22 Avent, Inc. Antimicrobial amorphous compositions
WO2016178041A1 (fr) * 2015-05-01 2016-11-10 Noxtak Technologies Vba. Dispositif de blindage contre l'électrosmog
US9687503B2 (en) 1999-12-30 2017-06-27 Avent, Inc. Devices for delivering oxygen to the wounds
EP3236479A1 (fr) * 2016-04-21 2017-10-25 Henkel AG & Co. KGaA Adhésif thermofusible ou composition de moulage électriquement conducteur
US10251392B2 (en) 2004-07-30 2019-04-09 Avent, Inc. Antimicrobial devices and compositions
CN114080424A (zh) * 2019-07-04 2022-02-22 科德宝两合公司 用于制备屏蔽电磁辐射的构件的方法
US11370926B2 (en) * 2016-03-29 2022-06-28 Tatsuta Electric Wire & Cable Co., Ltd. Conductive coating material and production method for shielded package using conductive coating material

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Publication number Priority date Publication date Assignee Title
US4695404A (en) * 1986-04-07 1987-09-22 Amerasia International Technology, Inc. Hyperconductive filled polymers
US4783279A (en) * 1986-08-05 1988-11-08 Lehmann & Voss & Co. Plastic mixture with electromagnetic shielding characteristics
US4830779A (en) * 1986-12-27 1989-05-16 Lion Corporation Electrically conductive resin composition
US4963291A (en) * 1988-06-13 1990-10-16 Bercaw Robert M Insulating electromagnetic shielding resin composition
US5075038A (en) * 1988-11-04 1991-12-24 Dow Corning Corporation Electrically conductive silicone compositions
US5229037A (en) * 1989-10-31 1993-07-20 Shin-Etsu Chemical Co., Ltd. Electroconductive silocone rubber composition containing a metal

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4695404A (en) * 1986-04-07 1987-09-22 Amerasia International Technology, Inc. Hyperconductive filled polymers
US4783279A (en) * 1986-08-05 1988-11-08 Lehmann & Voss & Co. Plastic mixture with electromagnetic shielding characteristics
US4830779A (en) * 1986-12-27 1989-05-16 Lion Corporation Electrically conductive resin composition
US4963291A (en) * 1988-06-13 1990-10-16 Bercaw Robert M Insulating electromagnetic shielding resin composition
US5075038A (en) * 1988-11-04 1991-12-24 Dow Corning Corporation Electrically conductive silicone compositions
US5229037A (en) * 1989-10-31 1993-07-20 Shin-Etsu Chemical Co., Ltd. Electroconductive silocone rubber composition containing a metal

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002538272A (ja) * 1999-03-04 2002-11-12 プレミックス・オーワイ 導電性の熱可塑性エラストマーおよびそれから作られた製品
US6638448B2 (en) 1999-03-04 2003-10-28 Premix Oy Electrically conductive thermoplastic elastomer and product made thereof
WO2000052710A1 (fr) * 1999-03-04 2000-09-08 Premix Oy Elastomere thermoplastique electroconducteur et produit en etant fait
WO2001041516A1 (fr) * 1999-11-30 2001-06-07 Welch Allyn Data Collection, Inc. Systeme d'instrument resistant aux charges electrostatiques
US6370003B1 (en) 1999-11-30 2002-04-09 Welch Allyn Data Collections, Inc. Electrostatic charge resistant instrument system
US9687503B2 (en) 1999-12-30 2017-06-27 Avent, Inc. Devices for delivering oxygen to the wounds
US10251392B2 (en) 2004-07-30 2019-04-09 Avent, Inc. Antimicrobial devices and compositions
US9888691B2 (en) 2004-07-30 2018-02-13 Avent, Inc. Antimicrobial silver compositions
US8900624B2 (en) 2004-07-30 2014-12-02 Kimberly-Clark Worldwide, Inc. Antimicrobial silver compositions
US9289378B2 (en) 2004-09-20 2016-03-22 Avent, Inc. Antimicrobial amorphous compositions
EP1991365A4 (fr) * 2006-02-08 2011-06-22 Acrymed Inc Procedes et compositions destines a des surfaces traitees avec des nanoparticules metalliques
EP1991365A2 (fr) * 2006-02-08 2008-11-19 Acrymed, Inc. Procedes et compositions destines a des surfaces traitees avec des nanoparticules metalliques
WO2016178041A1 (fr) * 2015-05-01 2016-11-10 Noxtak Technologies Vba. Dispositif de blindage contre l'électrosmog
US11370926B2 (en) * 2016-03-29 2022-06-28 Tatsuta Electric Wire & Cable Co., Ltd. Conductive coating material and production method for shielded package using conductive coating material
EP3236479A1 (fr) * 2016-04-21 2017-10-25 Henkel AG & Co. KGaA Adhésif thermofusible ou composition de moulage électriquement conducteur
WO2017182621A1 (fr) * 2016-04-21 2017-10-26 Henkel Ag & Co. Kgaa Composition d'adhésif thermofusible ou de moulage électroconductrice
CN114080424A (zh) * 2019-07-04 2022-02-22 科德宝两合公司 用于制备屏蔽电磁辐射的构件的方法

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