WO1994028337A1 - Joint conducteur/etanche - Google Patents

Joint conducteur/etanche Download PDF

Info

Publication number
WO1994028337A1
WO1994028337A1 PCT/US1994/006171 US9406171W WO9428337A1 WO 1994028337 A1 WO1994028337 A1 WO 1994028337A1 US 9406171 W US9406171 W US 9406171W WO 9428337 A1 WO9428337 A1 WO 9428337A1
Authority
WO
WIPO (PCT)
Prior art keywords
conductive
mesh
gasket
area
metal
Prior art date
Application number
PCT/US1994/006171
Other languages
English (en)
Inventor
Anthony T. Genova
Eric Krohto
Ron Saccuzzo
Original Assignee
Chomerics, 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 Chomerics, Inc. filed Critical Chomerics, Inc.
Priority to JP7501058A priority Critical patent/JPH07509772A/ja
Publication of WO1994028337A1 publication Critical patent/WO1994028337A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J15/00—Sealings
    • F16J15/02—Sealings between relatively-stationary surfaces
    • F16J15/06—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
    • F16J15/064—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces the packing combining the sealing function with other functions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J15/00—Sealings
    • F16J15/02—Sealings between relatively-stationary surfaces
    • F16J15/06—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
    • F16J15/10—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing
    • F16J15/12—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing with metal reinforcement or covering
    • F16J15/121—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing with metal reinforcement or covering with metal reinforcement

Definitions

  • the present invention relates to a gasket which is electrically conductive so as to provide lightning proection, EMI shielding, and grounding and which provides a good environmental seal. Moreover, it relates to a fluorosilicone/wire mesh composite gasket having good EMI/RFI shielding and lightning protection capabilities as well as environmental sealing properties.
  • EMI shielding is for providing protection against interference from electromagnetic energy, including radio frequency interference (RFI).
  • the shielding may protect an electronic device from external EMI and RFI or may prevent EMI or RFI from escaping from an electrical device, or both.
  • Grounding is the ability to properly terminate a panel or panels as to eliminate the threat of EMI to or from the equipment.
  • Lightning protection is for the ability of the gasket to carry the full current of a direct lightning strike in the vicinity of the gasket.
  • Environmental sealing is for protection against moisture, corrosion, dust, insects and similar environmental contamination encountered by electrical or electronic devices when in service.
  • EMI gaskets and seals have been made from the combination of rubber or elastomeric materials and metal wires or metal filaments. These gaskets are intended to function by the metal contacting the surfaces between which the gasket is assembled to provide the EMI shielding and the rubber or elastomeric material is intended to provide the environmental seal when compressed between the intended surfaces.
  • Other EMI gaskets have been provided in the form of an elastomeric binder containing electrically conductive particles, such as copper, iron, aluminum or nickel, coated with silver.
  • EMI gaskets have also been provided with a flexible foam rubber core having a wire exterior cover on the foam core such as a knitted or braided or otherwise woven wire fabric cover.
  • the foam rubber core is intended to provide resilience to assure that the wire cover makes good electrical contact when compressed between the intended surfaces and is also intended to provide an environmental seal between the intended surfaces.
  • a further form has been to impregnate a wire fabric with a gel which encapulates the mesh keeping it from corroding.
  • an object of this invention to provide an EMI gasket which provides electrical shielding and provides environmental sealing for not only the space between two surfaces but also for the conductive components which provide the EMI shielding in the gasket. Another object of this invention is to provide a corrosion resistant gasket which need not be made of noble metal components. Another object of this invention is to provide a method of EMI shielding, lightning protection, and grounding and environmentally sealing electrical or electronic components using such a gasket. Another objection on this invention is to provide lightning protection for the device(s) to which it is applied. Summary of the Invention
  • this invention provides an EMI gasket for electrically shielding, lightning protection, grounding and environmentally sealing the space between two surfaces comprising:
  • this invention produces an EMI/environmental gasket comprising an inner, substantially planar conductive layer formed of one or more layers of conductive mesh selected from the group consisting of metal mesh and metal plated plastic mesh; and a fluoroelastomer binder impregnating the mesh; and an outer nonconductive environmental seal area bonded to an outer periphery of the inner conductive area, the seal area being of a thickness greater than that of the inner layer and being formed of a fluoroelastomer.
  • this invention provides the above gasket wherein at least a portion of the conductive structure is positioned in a fluoroelastomer material and the nonconductive rim is positioned so as to deform into sealing contact with the surfaces around the metallic structure to seal the conductive structure from the environment when the gasket is compressed between the surfaces.
  • this invention provides a method of providing EMI shielding, lightning protection, grounding and environmental sealing the space between two surfaces by positioning a gasket as defined above between the two surfaces and compressing said gasket between said surfaces to deform the conductive material and establish electrical contact of the metallic structure with the surfaces.
  • Figure 1 shows a planar view of a gasket according to the present invention.
  • Figure 2 shows a cross sectional view of the portion of the gasket of Figure 1 taken along lines I-I.
  • Figure 3 shows a cross sectional view of the gasket of Figure 1 in use between two substrates.
  • Figure 4 shows the graphical presentation of the shielding effectiveness of the preferred embodiment of the present invention.
  • Figure 5 shows the amount of corrosion in the samples of Example 2 after 168 hours of salt fog testing.
  • Figure 6 shows the volume resistivity of the samples of Example 2.
  • the present invention relates to an EMI shield/environmental, lightning and grounding gasket. It is formed of a conductive area and a nonconductive, environmental seal area which is formed along the periphery of the conductive area regardless of whether the periphery is formed on the outer and/or inner portions of the gasket.
  • Figure 1 shows a preferred embodiment of the present invention. It can be used to seal a panel to an enclosure, such as an access panel on an electrical box or computer, or as an antenna seal on aircraft, such as an access panel on an aircraft fuel panel or other such equipment.
  • the gasket 1, as shown, has a substantially planar conductive area 2 and in this instance, inner and outer environmental seal areas 3A and 3B formed on the inner and outer peripheral areas of the conductive area.
  • a number of attachment holes 4 are also shown although other attachment means, such as conductive adhesives, channels, groups, etc. can be used.
  • Figure 2 shows the gasket of Figure 1 in cross section.
  • the conductive area 11 is formed of one or more layers of conductive mesh 12 embedded in a fluoroelastomer 13.
  • the fluoroelastomer may contain conductive filler, although it is not preferred, nor typically necessary.
  • the environmental seal area 14 is shown as being rounded, although other crosssectional shapes can be used (square, rectangular, oval, etc.)
  • the environmental seal area has a thickness substantially the same as that of the conductive area 11 or preferably greater than that of the conductive area so that upon application of a compressive force, as caused by the attachment of one substrate to the other, with gasket between, a complete environmental seal is established.
  • Figure 3 shows the crosssection of Figure 2 in such an application.
  • the seal area 24 is slightly compressed or flattened by the force applied to seal the two substrates 21, 22 together.
  • the conductive area 23 is thereby effectively protected from the outside elements, such as rain, jet fuel, solvents, dust, etc.
  • the mesh of the present invention may be formed of metal or a conductive plastic, such silver plated nylon yarn or fabrics.
  • a metal fiber such as steel, aluminum, copper or nickel or non-noble metal plated metal such as tin plated steel (FERREX mesh, available from Chomerics, Inc.), tin plated aluminum, tin plated copper, nickel, or aluminum; various alloys such as MONEL (a nickel copper alloy) or a noble metal plated non-noble metal such as silver plated nickel, copper, aluminum or steel mesh.
  • the conductive mesh may be formed as a woven fabric, a braid or a knit or as a nonwoven fabric, especially when a silver plated nylon is used.
  • the mesh may be an expanded metal grid formed of any of the metals described above.
  • One or more layers of the mesh may be used and they may, when multiple layers are used, be of the same or different materials. For example, with multiple layers, it may be desirable to have the most corrosion resistant mesh, such as a FERREX mesh at the outer surfaces with less corrosion resistant, but more conductive mesh layers, such as MONEL or silver plated aluminum mesh in between.
  • the mesh may extend above the surface of the fluoroelastomer so as to establish complete contact with the adjacent substrate. Alternatively, it may be equal with or slightly embedded into the fluoroelastomer provided that sufficient compressive force is applied so as to provide the necessary mating with the adjoining substrates.
  • the fluoroelastomer may be any natural or synthetic fluoro-containing elastomer or rubber. Preferably, it is either a fluoroolefin, such as polytetrafluoroethyelene (PTFE) or a fluorosilicone rubber.
  • PTFE polytetrafluoroethyelene
  • the more preferred material is a fluorosilicone due to its softness, ease of compounding, good physical properties (moisture resistant, solvent resistant, etc.) and cost.
  • One such fluorosilicone is available from Dow Corning as LS 2840 type silicone.
  • the seal area has a Shore A hardness of from about 40 to about 60 when cured, making it a very resilent, easily deflectable/compressible material. This reduces the amount of force required to obtain a good seal and contact between the gasket and the adjoining substrates.
  • the seal area may be foamed or unfoamed. Preferably, it is unfoamed. If foamed, it is preferred that the foam be closed celled.
  • a preferred method of forming the gasket is to take one or more layers of conductive mesh and embed or impregnate the mesh with a fluoroelastomer, which may or may not contain conductive fillers and form it into a sheet. The sheet is then cut to the desired configuration and the outer environmental seal is then bonded to the outer edges (and where applicable the inner edges of the gasket) .
  • a preferred method of bonding the outer environmental seal to the conductive area is by molding. The conductive area is placed into a mold which has a groove, channel or other design around the edges of the conductive area. A fluoroelastomer, such as fluorosilicone is then added to the mold, filling the groove or channel and touching the edges of the conductive area. The environmental seal is then cured so as to be bonded to the edge of the conductive area.
  • An alternative is to form a mold that has the desired gasket configuration, place the conductive mesh into the region of the mold which will form the conductive area and then add the fluoroelastomer to the mold in an amount so that it encompasses both the conductive area as well as the outer environmental seal area.
  • a further method is to form the conductive area, such as in a roll mill and separately form the environmental seal and then bond the two together along their edges via a separate bonding material.
  • a gasket was formed by taking 8 layers of tin plated steel conductive mesh stockings and flattening each of the layers. The flattened layers were then laid on top of each other and impregnated with a nonconductive fluorosilicone rubber dissolved in a solvent. The sheet was dried and then die cut to the desired shape. The die cut gasket was placed into a mold and nonconductive fluorosilicone was applied to the outer edges of the sheet. The entire sheet was then vulcanized and bonded into a unitary structure.
  • the gasket was then tested according to Military Standard Test 285, EMI Shielding, by placing the gasket around an opening, such as a shielded room, so as to be between the outer wall of the room and a coverplate which effectively sealed the room from the outside.
  • a transmitter was placed outside the room about one meter from the center of the opening and a receiver was placed inside the room, in line with the transmitter.
  • Values of the signal received were measured at a range of frequencies from 1 Mhz to 18,000 Mhz for both the shielded and un-shielded opening. The difference between the values at the same frequency represent the attenuation or shielding effectiveness obtained with the material.
  • Figure 4 shows the results of such testing. As can be clearly seen, the present invention provided excellent shielding over a wide range of frequencies.
  • A. - Mesh was formed of aluminum wire with no outer non-conductive layer.
  • Figure 5 shows the corrosion values obtained for the samples.
  • Figure 6 shows the volume resistivity of the gaskets measured before and after salt fog exposure.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)

Abstract

L'invention se rapporte à un joint d'étanchéité/de blindage contre les interférences électromagnétiques, qui est constitué d'une partie conductrice interne (11) et d'une partie d'étanchéité non conductrice externe (14). La partie interne (11) est formée par une ou plusieurs couches d'un treillis électroconducteur (12) noyé dans un fluoroélastomère (13) tel qu'une fluorosilicone. La couche externe (14) est formée d'un fluoroélastomère non conducteur et sa hauteur est égale ou supérieure à celle de la partie interne, de sorte qu'elle forme une bonne jointure d'étanchéité autour du périmètre de la partie conductrice, lorsqu'elle est placée entre deux substrats en contact étroit.
PCT/US1994/006171 1993-06-02 1994-06-02 Joint conducteur/etanche WO1994028337A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP7501058A JPH07509772A (ja) 1993-06-02 1994-06-02 導電性／シーリングガスケット

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US7116293A 1993-06-02 1993-06-02
US08/071,162 1993-06-02

Publications (1)

Publication Number Publication Date
WO1994028337A1 true WO1994028337A1 (fr) 1994-12-08

Family

ID=22099662

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1994/006171 WO1994028337A1 (fr) 1993-06-02 1994-06-02 Joint conducteur/etanche

Country Status (3)

Country Link
JP (1) JPH07509772A (fr)
CA (1) CA2141709A1 (fr)
WO (1) WO1994028337A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5791654A (en) * 1992-08-19 1998-08-11 The Boeing Company Corrosion resistant gasket in combination with aircraft antenna
WO1999002899A1 (fr) * 1997-07-09 1999-01-21 Siemens Aktiengesellschaft Garniture plate a fonction de conducteur de protection
US6454276B2 (en) * 1992-08-19 2002-09-24 The Boeing Company Corrosion resistant gasket for aircraft
US6454267B1 (en) * 1992-08-19 2002-09-24 The Boeing Company Corrosion resistant gasket for aircraft
US6719293B1 (en) * 1992-08-19 2004-04-13 The Boeing Company Corrosion resistant gasket for aircraft
US8864141B2 (en) 2008-01-17 2014-10-21 Airbus Operations Limited Blade seal
CN105246779A (zh) * 2013-05-31 2016-01-13 派克汉尼芬公司 具有加固密封的改进的燃料箱检视门密封垫

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3140342A (en) * 1963-07-05 1964-07-07 Chomerics Inc Electrical shielding and sealing gasket
US4037009A (en) * 1976-08-11 1977-07-19 Metex Corporation Conductive elastomeric elements
US5294270A (en) * 1991-02-20 1994-03-15 Instrument Specialties Company, Inc. Heat-treated wire-mesh EMI/RFI shielding gasket

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3140342A (en) * 1963-07-05 1964-07-07 Chomerics Inc Electrical shielding and sealing gasket
US4037009A (en) * 1976-08-11 1977-07-19 Metex Corporation Conductive elastomeric elements
US5294270A (en) * 1991-02-20 1994-03-15 Instrument Specialties Company, Inc. Heat-treated wire-mesh EMI/RFI shielding gasket

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5791654A (en) * 1992-08-19 1998-08-11 The Boeing Company Corrosion resistant gasket in combination with aircraft antenna
US6454276B2 (en) * 1992-08-19 2002-09-24 The Boeing Company Corrosion resistant gasket for aircraft
US6454267B1 (en) * 1992-08-19 2002-09-24 The Boeing Company Corrosion resistant gasket for aircraft
US6719293B1 (en) * 1992-08-19 2004-04-13 The Boeing Company Corrosion resistant gasket for aircraft
WO1999002899A1 (fr) * 1997-07-09 1999-01-21 Siemens Aktiengesellschaft Garniture plate a fonction de conducteur de protection
US8864141B2 (en) 2008-01-17 2014-10-21 Airbus Operations Limited Blade seal
CN105246779A (zh) * 2013-05-31 2016-01-13 派克汉尼芬公司 具有加固密封的改进的燃料箱检视门密封垫

Also Published As

Publication number Publication date
CA2141709A1 (fr) 1994-12-08
JPH07509772A (ja) 1995-10-26

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