US20020029893A1 - Apparatus and method for shielding electromagnetic wave - Google Patents

Apparatus and method for shielding electromagnetic wave Download PDF

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US20020029893A1
US20020029893A1 US09/292,833 US29283399A US2002029893A1 US 20020029893 A1 US20020029893 A1 US 20020029893A1 US 29283399 A US29283399 A US 29283399A US 2002029893 A1 US2002029893 A1 US 2002029893A1
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electromagnetic wave
coil
circuit
carbon fiber
fiber structures
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US6426457B1 (en
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Junichi Toyoda
Sakan Iwashita
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Sony Corp
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    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073Shielding materials
    • H05K9/0081Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • H05K9/0088Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising a plurality of shielding layers; combining different shielding material structure
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00Details of, or arrangements associated with, antennas
    • H01Q1/52Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure
    • H01Q1/526Electromagnetic shields
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00Screening of apparatus or components against electric or magnetic fields
    • H05K9/0007Casings
    • H05K9/002Casings with localised screening
    • H05K9/0022Casings with localised screening of components mounted on printed circuit boards [PCB]
    • H05K9/0024Shield cases mounted on a PCB, e.g. cans or caps or conformal shields
    • H05K9/003Shield cases mounted on a PCB, e.g. cans or caps or conformal shields made from non-conductive materials comprising an electro-conductive coating
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00Screening of apparatus or components against electric or magnetic fields
    • H05K9/0007Casings
    • H05K9/002Casings with localised screening
    • H05K9/0022Casings with localised screening of components mounted on printed circuit boards [PCB]
    • H05K9/0024Shield cases mounted on a PCB, e.g. cans or caps or conformal shields
    • H05K9/0031Shield cases mounted on a PCB, e.g. cans or caps or conformal shields combining different shielding materials
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/15Details of package parts other than the semiconductor or other solid state devices to be connected
    • H01L2924/161Cap
    • H01L2924/1615Shape
    • H01L2924/16152Cap comprising a cavity for hosting the device, e.g. U-shaped cap

Definitions

  • the present invention relates to an electromagnetic wave shielding apparatus and an electromagnetic wave shielding method used for electric circuits, electronic circuits and the like.
  • a circuit board 100 of a related art electronic circuit arrangement shown in FIG. 7 has electronic parts 101 and 102 which generate electromagnetic waves 103 in the directions shown by the arrows, and which circuit board 100 is covered with a case 104 .
  • the electromagnetic waves 103 are reflected from the inner surfaces of the case 104 and leaked to the outside through a small gap 105 and/or wiring.
  • the case 104 if being made from a metal, produces a high-frequency current when it is exposed to the electromagnetic waves, and therefore, the case 104 becomes a re-generating source of electromagnetic wave noise.
  • an electromagnetic wave absorbing member 110 is fixed on a surface, facing to the electronic parts, of the inner wall of the case 104 .
  • the electromagnetic wave absorbing member 110 functions to absorb or attenuate the electromagnetic waves 103 and prevent leakage of the electromagnetic waves 103 to the outside as much as possible, to reduce the degree of reflection of the electromagnetic waves 103 and decay the electromagnetic waves 103 , and to prevent re-generating of electromagnetic wave noise from the case 104 .
  • the related art electromagnetic wave absorbing member 110 has disadvantages that it takes a lot of time to lay out the member 110 because the member 110 must be stuck on the inner surface of the shield case 104 with an adhesive double coated tape or the like by an operator in such a manner as to ensure the optimum absorption of electromagnetic waves, and that the weight of the circuit board 100 becomes very large because the member 110 having a large thickness is stuck on the inner surface of the case 104 with an adhesive double coated tape or the like.
  • An object of the present invention is to provide an electromagnetic wave shielding apparatus and an electromagnetic wave shielding method, which are capable of simply obtaining an electromagnetic wave shielding function without increasing the weight of the apparatus.
  • an electromagnetic wave shielding apparatus for shielding electromagnetic waves generated from a circuit so as to prevent the electromagnetic waves from being leaked to the outside of the circuit, including: a metal member disposed in such a manner as to be opposed to the circuit; and an electromagnetic wave absorbing member disposed on the metal member; wherein the electromagnetic absorbing member is composed of a carbon layer and coil-like carbon fiber structures.
  • the electromagnetic wave absorbing member is composed of the carbon layer and the coil-like carbon fiber structures which are formed on the metal member, it can be made lighter than that of the related art electromagnetic wave absorbing member, and since the coil-like carbon fiber structures are electrically conductive, the electromagnetic wave absorbing member is capable of efficiently absorb electromagnetic waves generated from an electromagnetic wave generating source through the coil-like carbon fiber structures.
  • the carbon layer is formed on a surface, facing to the circuit, of the metal members; one-end portions of the coil-like carbon fiber structures are connected to the carbon layer; and the axial directions of the coil-like carbon fiber structures are substantially perpendicular to an electromagnetic wave generating source.
  • an electromagnetic wave shielding method for shielding electromagnetic waves generated from a circuit so as to prevent the electromagnetic waves from being leaked to the outside of the circuit, including the steps of: forming an electromagnetic wave absorbing member on a metal member; and disposing the metal member in such a manner that the metal member is opposed to the circuit; wherein the electromagnetic wave member is composed of a carbon layer and coil-like carbon fiber structures produced by a chemical vapor deposition process based on thermal decomposition.
  • the electromagnetic wave absorbing member can be simply formed on the metal member by chemical vapor deposition, being made lightweight, and is capable of efficiently absorb electromagnetic waves.
  • the carbon layer is formed on a surface, facing to the circuit, of the metal members; one-end portions of the coil-like carbon fiber structures are connected to the carbon layer; and the axial directions of the coil-like carbon fiber structures are substantially perpendicular to an electromagnetic wave generating source.
  • the electromagnetic wave absorbing member is composed of the carbon layer and the coil-like carbon fiber structures which are formed on the metal member, it can be made lighter than that of the related art electromagnetic wave absorbing member, and since the coil-like carbon fiber structures are electrically conductive, the electromagnetic wave absorbing member is capable of efficiently absorb electromagnetic waves generated from an electromagnetic wave generating source through the coil-like carbon fiber structures.
  • a shield case for shielding a circuit can be simply prepared by working the metal member on which the electromagnetic wave absorbing member has been formed, into a desired shape.
  • FIG. 1 is a schematic view showing one example of a circuit board including an electromagnetic wave shielding apparatus according to the present invention
  • FIG. 2 is a perspective view, with parts partially cutaway, showing the circuit board including the electromagnetic wave shielding apparatus shown in FIG. 1;
  • FIG. 3 is an enlarged sectional view showing a shield case and an electromagnetic wave absorbing member
  • FIG. 4 is a schematic view showing one example of a method of forming a carbon layer and coil-like carbon fiber structures on a plate-like raw material of the shield case by chemical vapor deposition;
  • FIG. 5 is a perspective view showing one example of the coil-like carbon fiber structure
  • FIG. 6 is a flow chart showing one example of a method of forming coil-like carbon fiber structures on a plate-like raw material
  • FIG. 7 is a schematic view showing a circuit board including a related art shield case.
  • FIG. 8 is a schematic view showing a circuit board including a related art shield case having an electromagnetic wave absorbing member.
  • FIG. 1 shows a circuit board 12 on which an electromagnetic wave shielding apparatus 10 of the present invention is mounted.
  • the circuit board 12 has a conductor pattern of an electric or electronic circuit, and for example, electronic parts 14 , 16 and 18 are electrically connected to the conductor pattern.
  • a box-shaped shield case 20 is mounted on the circuit board 12 in such a manner as to cover the electronic parts 14 , 16 and 18 .
  • An electromagnetic wave absorbing member 30 is formed over an inner surface 22 of the shield case 20 .
  • the electromagnetic wave absorbing member 30 is formed, as shown in FIGS. 1 and 2, into a sheet composed of, as shown by the partial enlarged view of FIG. 3, a carbon layer 60 and numberless coil-like carbon fiber structures (may be called carbon coils) 40 .
  • the coil-like carbon fiber structures 40 substantially parallel to each other, are formed on the carbon layer 60 in the direction substantially perpendicular thereto.
  • one-end sides 41 of the coil-like carbon fiber structures 40 are connected to the carbon layer 60 and the other end sides thereof are taken as free ends or entangled with each other.
  • the coil-like carbon fiber structures are also called helical coil-like carbon fiber structures, which are basically composed of carbon fibers produced by thermal decomposition of a hydrocarbon gas.
  • One example of the coil-like carbon fiber structure 40 will be described with reference to FIG. 5.
  • the coil-like carbon fiber structure 40 shown in FIG. 5 is electrically conductive.
  • the fiber diameter (fiber thickness) L 1 of the fiber structure 40 is in a range of 0.05 to 5 ⁇ m.
  • the coil outside diameter L 2 of the coil structure 40 is about 2 to 10 times greater than the fiber diameter L 1 , that is, in a range of 0.1 to 50 ⁇ m.
  • the axial length of the fiber structure 40 is in a range of 3 to 30 ⁇ m.
  • the number of turns of the fiber structure 40 is in a range of about 1 to 500. Further, the number of turns ⁇ (unit length (10 ⁇ m)/coil outside diameter L 2 ) is in a range of 5 to 50.
  • the coil-like carbon fiber structures 40 having the above configuration which are essentially made from carbon, can be obtained by vapor-phase thermal decomposition of a gas containing a hydrocarbon based gas, particularly, acetylene gas, in a system in which a transition metal is present, at a temperature ranging from 700 to 800° C.
  • a gas containing a hydrocarbon based gas particularly, acetylene gas
  • hydrocarbon based gases may include an unsaturated hydrocarbon gas such as acetylene, ethylene, or propylene gas and a saturated hydrocarbon gas such as ethane, propane, or butane gas.
  • unsaturated hydrocarbon gas such as acetylene, ethylene, or propylene gas
  • a saturated hydrocarbon gas such as ethane, propane, or butane gas.
  • acetylene gas is most preferably used from the viewpoint of the catalytic action of a transition metal.
  • the above hydrocarbon gas may be mixed with hydrogen.
  • a diluting gas such as argon, nitrogen, or helium can be of course used for controlling the shape of the coil-like carbon fiber structure 40 .
  • a plate-like raw material 74 which will be taken as a flat-plate shield case 20 , is first prepared.
  • the plate-like raw material 74 is made from a conductive material such as iron, nickel, copper or permalloy and has a thickness ranging from 0.1 to 0.5 mm.
  • the plate-like raw material 74 for forming the shield case 20 is coated with powder 76 of nickel as nuclei for growth of coil-like carbon fiber structures 40 on the conductive plate-like raw material 74 .
  • the powder 76 of nickel has an average particle size of about 5 ⁇ m.
  • the plate-like raw material 74 coated with the powder 76 of nickel is mounted on a susceptor 72 in a reactor 70 shown in FIG. 4.
  • the plate-like raw material 74 coated with the powder 76 of nickel is heated in the reactor 70 at a temperature ranging from 700 to 800° C., and at the same time, a reaction gas 80 is uniformly supplied to the plate-like raw material 74 from a gas inlet 78 .
  • a mixed gas of acetylene, hydrogen and chiophene as the reaction gas is allowed to flow to the powder 76 of nickel on the plate-like raw material 74 through a special shower head.
  • the mixed gas (reaction gas) thus supplied is decomposed on the surface of the plate-like raw material 74 .
  • a carbon component is deposited as a carbon layer 60 shown in FIG. 3.
  • part of the carbon component is grown in vapor-phase, with crystal grains of nickel taken as nuclei, on the carbon layer 60 formed on the plate-like raw material 74 in the direction substantially perpendicular thereto, to form coil-like carbon fiber structures 40 .
  • the coil-like carbon fiber structures 40 grow toward the flow-in direction of the reaction gas 80 .
  • the numberless coil-like carbon fiber structures 40 grow in such a manner as to be arranged along a specific direction as shown in FIGS. 3 and 4. In this case, it is important that the reaction gas 80 uniformly flows in the direction R, that is, in the direction perpendicular, or substantially perpendicular to the plate-like metal raw material 74 .
  • step SP 6 the plate-like raw material 74 formed as shown in FIG. 4, which is removed from the reactor 70 , is cut into a specific dimension and is bent to form a shield case 20 shown in FIGS. 1 and 2. In this way, the electromagnetic wave absorbing member 30 is formed over the inner surface 22 of the shield case 20 .
  • the electromagnetic wave absorbing member 30 can be formed over the inner surface 22 of the shield case 20 , it can absorb the electromagnetic waves 90 without leakage thereof to the outside. That is to say, the electromagnetic wave absorbing member 30 is desirable to be formed on a widest first surface 22 a and four side surfaces 22 b of the inner surface 22 as shown in FIGS. 1 and 2.
  • the electromagnetic wave absorbing member 30 can be formed over the inner surface of the shield case 20 by chemical vapor deposition, the present invention has the following merits:
  • the electromagnetic wave absorbing member 30 is formed over the inner surface 22 of the shield case 20 by chemical vapor deposition, and accordingly, it is possible to thinly form the electromagnetic wave absorbing member 30 and to eliminate the fear that the member 30 is peeled from the inner surface of the shield case 20 .
  • the electromagnetic wave absorbing member 30 can be formed at a time over the inner surface 22 of the shield case 20 , it is possible to increase the ability of preventing the leakage of the electromagnetic waves 90 to the outside.
  • the coil-like carbon fiber structures 40 are formed in the directions perpendicular or substantially perpendicular to the inner surface of the shield case 20 ; however, the present invention is not limited thereto.
  • the coil-like carbon fiber structures 40 may be slightly tilted with respect to the inner surface of the shield case 20 . In this case, the same effect can be obtained.
  • the electromagnetic wave absorbing member 30 may be formed by tightening the coil-like carbon fiber structures by means of a non-conductive material such as rubber or plastic.

Abstract

Disclosed is an electromagnetic wave shielding apparatus for shielding electromagnetic waves generated from a circuit so as to prevent the electromagnetic waves from being leaked to the outside of the circuit. The apparatus includes a metal member disposed in such a manner as to be opposed to the circuit, and an electromagnetic wave absorbing member disposed on the metal member, wherein the electromagnetic absorbing member is composed of a carbon layer and coil-like carbon fiber structures. The apparatus is allowed to simply obtain an electromagnetic wave absorbing function without increasing the weight of the apparatus.

Description

    BACKGROUND OF THE INVENTION
  • The present invention relates to an electromagnetic wave shielding apparatus and an electromagnetic wave shielding method used for electric circuits, electronic circuits and the like. [0001]
  • In electric circuit arrangements, electronic circuit arrangements and the like, it is necessary to prevent electromagnetic waves generated from electronic parts and the like installed in the circuit arrangement from being leaked to the outside. For example, a [0002] circuit board 100 of a related art electronic circuit arrangement shown in FIG. 7 has electronic parts 101 and 102 which generate electromagnetic waves 103 in the directions shown by the arrows, and which circuit board 100 is covered with a case 104. In this case, the electromagnetic waves 103 are reflected from the inner surfaces of the case 104 and leaked to the outside through a small gap 105 and/or wiring. The case 104, if being made from a metal, produces a high-frequency current when it is exposed to the electromagnetic waves, and therefore, the case 104 becomes a re-generating source of electromagnetic wave noise.
  • To cope with such an inconvenience, in the related art electronic circuit arrangement, as shown in FIG. 8, an electromagnetic [0003] wave absorbing member 110 is fixed on a surface, facing to the electronic parts, of the inner wall of the case 104. The electromagnetic wave absorbing member 110 functions to absorb or attenuate the electromagnetic waves 103 and prevent leakage of the electromagnetic waves 103 to the outside as much as possible, to reduce the degree of reflection of the electromagnetic waves 103 and decay the electromagnetic waves 103, and to prevent re-generating of electromagnetic wave noise from the case 104.
  • The related art electromagnetic [0004] wave absorbing member 110, however, has disadvantages that it takes a lot of time to lay out the member 110 because the member 110 must be stuck on the inner surface of the shield case 104 with an adhesive double coated tape or the like by an operator in such a manner as to ensure the optimum absorption of electromagnetic waves, and that the weight of the circuit board 100 becomes very large because the member 110 having a large thickness is stuck on the inner surface of the case 104 with an adhesive double coated tape or the like.
  • SUMMARY OF THE INVENTION
  • An object of the present invention is to provide an electromagnetic wave shielding apparatus and an electromagnetic wave shielding method, which are capable of simply obtaining an electromagnetic wave shielding function without increasing the weight of the apparatus. [0005]
  • To achieve the above object, according to a first aspect of the present invention, there is provided an electromagnetic wave shielding apparatus for shielding electromagnetic waves generated from a circuit so as to prevent the electromagnetic waves from being leaked to the outside of the circuit, including: a metal member disposed in such a manner as to be opposed to the circuit; and an electromagnetic wave absorbing member disposed on the metal member; wherein the electromagnetic absorbing member is composed of a carbon layer and coil-like carbon fiber structures. [0006]
  • With this configuration, since the electromagnetic wave absorbing member is composed of the carbon layer and the coil-like carbon fiber structures which are formed on the metal member, it can be made lighter than that of the related art electromagnetic wave absorbing member, and since the coil-like carbon fiber structures are electrically conductive, the electromagnetic wave absorbing member is capable of efficiently absorb electromagnetic waves generated from an electromagnetic wave generating source through the coil-like carbon fiber structures. [0007]
  • In the above apparatus, preferably, the carbon layer is formed on a surface, facing to the circuit, of the metal members; one-end portions of the coil-like carbon fiber structures are connected to the carbon layer; and the axial directions of the coil-like carbon fiber structures are substantially perpendicular to an electromagnetic wave generating source. With this configuration, electromagnetic waves generated from an electromagnetic wave generating source can be efficiently absorbed in the carbon layer through the coil-like carbon fiber structures. [0008]
  • According to a second aspect of the present invention, there is provided an electromagnetic wave shielding method for shielding electromagnetic waves generated from a circuit so as to prevent the electromagnetic waves from being leaked to the outside of the circuit, including the steps of: forming an electromagnetic wave absorbing member on a metal member; and disposing the metal member in such a manner that the metal member is opposed to the circuit; wherein the electromagnetic wave member is composed of a carbon layer and coil-like carbon fiber structures produced by a chemical vapor deposition process based on thermal decomposition. [0009]
  • With this configuration, the electromagnetic wave absorbing member can be simply formed on the metal member by chemical vapor deposition, being made lightweight, and is capable of efficiently absorb electromagnetic waves. [0010]
  • In the above method, preferably, the carbon layer is formed on a surface, facing to the circuit, of the metal members; one-end portions of the coil-like carbon fiber structures are connected to the carbon layer; and the axial directions of the coil-like carbon fiber structures are substantially perpendicular to an electromagnetic wave generating source. [0011]
  • With this configuration, since the electromagnetic wave absorbing member is composed of the carbon layer and the coil-like carbon fiber structures which are formed on the metal member, it can be made lighter than that of the related art electromagnetic wave absorbing member, and since the coil-like carbon fiber structures are electrically conductive, the electromagnetic wave absorbing member is capable of efficiently absorb electromagnetic waves generated from an electromagnetic wave generating source through the coil-like carbon fiber structures. [0012]
  • According to the present invention, a shield case for shielding a circuit can be simply prepared by working the metal member on which the electromagnetic wave absorbing member has been formed, into a desired shape.[0013]
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a schematic view showing one example of a circuit board including an electromagnetic wave shielding apparatus according to the present invention; [0014]
  • FIG. 2 is a perspective view, with parts partially cutaway, showing the circuit board including the electromagnetic wave shielding apparatus shown in FIG. 1; [0015]
  • FIG. 3 is an enlarged sectional view showing a shield case and an electromagnetic wave absorbing member; [0016]
  • FIG. 4 is a schematic view showing one example of a method of forming a carbon layer and coil-like carbon fiber structures on a plate-like raw material of the shield case by chemical vapor deposition; [0017]
  • FIG. 5 is a perspective view showing one example of the coil-like carbon fiber structure; [0018]
  • FIG. 6 is a flow chart showing one example of a method of forming coil-like carbon fiber structures on a plate-like raw material; [0019]
  • FIG. 7 is a schematic view showing a circuit board including a related art shield case; and [0020]
  • FIG. 8 is a schematic view showing a circuit board including a related art shield case having an electromagnetic wave absorbing member.[0021]
  • DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
  • Hereinafter, one preferred embodiment of the present invention will be described with reference to the accompanying drawings. [0022]
  • FIG. 1 shows a [0023] circuit board 12 on which an electromagnetic wave shielding apparatus 10 of the present invention is mounted. The circuit board 12 has a conductor pattern of an electric or electronic circuit, and for example, electronic parts 14, 16 and 18 are electrically connected to the conductor pattern.
  • A box-[0024] shaped shield case 20 is mounted on the circuit board 12 in such a manner as to cover the electronic parts 14, 16 and 18.
  • An electromagnetic [0025] wave absorbing member 30 is formed over an inner surface 22 of the shield case 20. The electromagnetic wave absorbing member 30 is formed, as shown in FIGS. 1 and 2, into a sheet composed of, as shown by the partial enlarged view of FIG. 3, a carbon layer 60 and numberless coil-like carbon fiber structures (may be called carbon coils) 40. The coil-like carbon fiber structures 40, substantially parallel to each other, are formed on the carbon layer 60 in the direction substantially perpendicular thereto. To be more specific, one-end sides 41 of the coil-like carbon fiber structures 40 are connected to the carbon layer 60 and the other end sides thereof are taken as free ends or entangled with each other. The coil-like carbon fiber structures are also called helical coil-like carbon fiber structures, which are basically composed of carbon fibers produced by thermal decomposition of a hydrocarbon gas. One example of the coil-like carbon fiber structure 40 will be described with reference to FIG. 5.
  • The coil-like [0026] carbon fiber structure 40 shown in FIG. 5 is electrically conductive. The fiber diameter (fiber thickness) L1 of the fiber structure 40 is in a range of 0.05 to 5 μm. The coil outside diameter L2 of the coil structure 40 is about 2 to 10 times greater than the fiber diameter L1, that is, in a range of 0.1 to 50 μm. The axial length of the fiber structure 40 is in a range of 3 to 30 μm. The number of turns of the fiber structure 40 is in a range of about 1 to 500. Further, the number of turns×(unit length (10 μm)/coil outside diameter L2) is in a range of 5 to 50.
  • The coil-like [0027] carbon fiber structures 40 having the above configuration, which are essentially made from carbon, can be obtained by vapor-phase thermal decomposition of a gas containing a hydrocarbon based gas, particularly, acetylene gas, in a system in which a transition metal is present, at a temperature ranging from 700 to 800° C.
  • Examples of the above hydrocarbon based gases may include an unsaturated hydrocarbon gas such as acetylene, ethylene, or propylene gas and a saturated hydrocarbon gas such as ethane, propane, or butane gas. In particular, acetylene gas is most preferably used from the viewpoint of the catalytic action of a transition metal. [0028]
  • The above hydrocarbon gas may be mixed with hydrogen. In addition to this, a diluting gas such as argon, nitrogen, or helium can be of course used for controlling the shape of the coil-like [0029] carbon fiber structure 40.
  • One example of a method of forming the electromagnetic [0030] wave absorbing member 30, which is composed of the carbon layer 60 and the coil-like carbon fiber structures 40 as shown in FIG. 3, on the inner surface 22 of the shield case 20 will be described with reference to FIGS. 4 and 6.
  • A plate-like [0031] raw material 74, which will be taken as a flat-plate shield case 20, is first prepared. The plate-like raw material 74 is made from a conductive material such as iron, nickel, copper or permalloy and has a thickness ranging from 0.1 to 0.5 mm.
  • Next, at step SP[0032] 1 in FIG. 6, the plate-like raw material 74 for forming the shield case 20 is coated with powder 76 of nickel as nuclei for growth of coil-like carbon fiber structures 40 on the conductive plate-like raw material 74. The powder 76 of nickel has an average particle size of about 5 μm. The plate-like raw material 74 coated with the powder 76 of nickel is mounted on a susceptor 72 in a reactor 70 shown in FIG. 4. At step SP2, the plate-like raw material 74 coated with the powder 76 of nickel is heated in the reactor 70 at a temperature ranging from 700 to 800° C., and at the same time, a reaction gas 80 is uniformly supplied to the plate-like raw material 74 from a gas inlet 78. To be more specific, a mixed gas of acetylene, hydrogen and chiophene as the reaction gas is allowed to flow to the powder 76 of nickel on the plate-like raw material 74 through a special shower head.
  • The mixed gas (reaction gas) thus supplied is decomposed on the surface of the plate-like [0033] raw material 74. Thus, at step SP3, a carbon component is deposited as a carbon layer 60 shown in FIG. 3. At step SP4, part of the carbon component is grown in vapor-phase, with crystal grains of nickel taken as nuclei, on the carbon layer 60 formed on the plate-like raw material 74 in the direction substantially perpendicular thereto, to form coil-like carbon fiber structures 40. To be more specific, the coil-like carbon fiber structures 40 grow toward the flow-in direction of the reaction gas 80.
  • At step SP[0034] 5, the numberless coil-like carbon fiber structures 40 grow in such a manner as to be arranged along a specific direction as shown in FIGS. 3 and 4. In this case, it is important that the reaction gas 80 uniformly flows in the direction R, that is, in the direction perpendicular, or substantially perpendicular to the plate-like metal raw material 74.
  • At step SP[0035] 6, the plate-like raw material 74 formed as shown in FIG. 4, which is removed from the reactor 70, is cut into a specific dimension and is bent to form a shield case 20 shown in FIGS. 1 and 2. In this way, the electromagnetic wave absorbing member 30 is formed over the inner surface 22 of the shield case 20.
  • Electromagnetic waves generated from the [0036] electronic parts 14, 16 and 18 shown in FIG. 1, which are the electromagnetic wave generating sources, is made incident on each of the coil-like carbon fiber structures 40 shown in FIG. 3 in the axial direction thereof. At this time, the coil-like carbon fiber structure 40 produces an induction current “i”. Since the coil-like carbon fiber structure 40 is positioned substantially perpendicularly to the electronic parts 14, 16 and 18 as the electromagnetic wave generating sources, it receives the electromagnetic waves (variable magnetic filed) in the axial direction and introduces these electromagnetic wavers to the carbon layer 60. The carbon layer 60 absorbs the electromagnetic waves thus introduced by the coil-like carbon fiber structures 40.
  • Since the electromagnetic [0037] wave absorbing member 30 can be formed over the inner surface 22 of the shield case 20, it can absorb the electromagnetic waves 90 without leakage thereof to the outside. That is to say, the electromagnetic wave absorbing member 30 is desirable to be formed on a widest first surface 22 a and four side surfaces 22 b of the inner surface 22 as shown in FIGS. 1 and 2.
  • Since the electromagnetic [0038] wave absorbing member 30 can be formed over the inner surface of the shield case 20 by chemical vapor deposition, the present invention has the following merits:
  • (1) Unlike the related art electromagnetic wave absorbing member stuck on the metal member with an adhesive double coated tape, the electromagnetic [0039] wave absorbing member 30 is formed over the inner surface 22 of the shield case 20 by chemical vapor deposition, and accordingly, it is possible to thinly form the electromagnetic wave absorbing member 30 and to eliminate the fear that the member 30 is peeled from the inner surface of the shield case 20.
  • (2) The period of time required for layout of the electromagnetic [0040] wave absorbing member 30 can be shortened. That is to say, since the leakage level of electromagnetic waves to the outside is lowered, the margin of the circuit design is increased and thereby the final adjustment of the circuit can be omitted.
  • (3) Since the electromagnetic [0041] wave absorbing member 30 is stuck on the metal member by chemical vapor deposition (CVD) based on thermal decomposition, it is possible to thinly form the member 30, to eliminate the sticking work using an adhesive double coated tape, and to reduce the weight of the member 30.
  • (4) Since the electromagnetic [0042] wave absorbing member 30 can be formed at a time over the inner surface 22 of the shield case 20, it is possible to increase the ability of preventing the leakage of the electromagnetic waves 90 to the outside.
  • In the above embodiment, description is made by way of the example in which the box-shaped [0043] shield case 20 is disposed on an electric or electronic circuit board; however, the shape of the shield case 20 and the shape of the electromagnetic wave absorbing member 30 formed on the shield case 20 are not limited to those shown in the figures.
  • In the example shown in the figures, the coil-like [0044] carbon fiber structures 40 are formed in the directions perpendicular or substantially perpendicular to the inner surface of the shield case 20; however, the present invention is not limited thereto. For example, the coil-like carbon fiber structures 40 may be slightly tilted with respect to the inner surface of the shield case 20. In this case, the same effect can be obtained.
  • The electromagnetic [0045] wave absorbing member 30 may be formed by tightening the coil-like carbon fiber structures by means of a non-conductive material such as rubber or plastic.
  • While the preferred embodiment has been described using specific terms, such description is illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims. [0046]

Claims (5)

What is claimed is:
1. An electromagnetic wave shielding apparatus for shielding electromagnetic waves generated from a circuit so as to prevent the electromagnetic waves from being leaked to the outside of the circuit, comprising:
a metal member disposed in such a manner as to be opposed to the circuit; and
an electromagnetic wave absorbing member disposed on said metal member;
wherein said electromagnetic absorbing member is composed of a carbon layer and coil-like carbon fiber structures.
2. An electromagnetic wave shielding apparatus according to claim 1, wherein said carbon layer is formed on a surface, facing to said circuit, of said metal members; one-end portions of said coil-like carbon fiber structures are connected to said carbon layer; and the axial directions of said coil-like carbon fiber structures are substantially perpendicular to an electromagnetic wave generating source.
3. An electromagnetic wave shielding method for shielding electromagnetic waves generated from a circuit so as to prevent the electromagnetic waves from being leaked to the outside of the circuit, comprising the steps of:
forming an electromagnetic wave absorbing member on a metal member; and
disposing said metal member in such a manner that said metal member is opposed to the circuit;
wherein said electromagnetic wave member is composed of a carbon layer and coil-like carbon fiber structures produced by a chemical vapor deposition process based on thermal decomposition.
4. An electromagnetic wave shielding method according to claim 3, wherein said carbon layer is formed on a surface, facing to said circuit, of said metal members; one-end portions of said coil-like carbon fiber structures are connected to said carbon layer; and the axial directions of said coil-like carbon fiber structures are substantially perpendicular to an electromagnetic wave generating source.
5. An electromagnetic wave shielding method according to claim 3, further comprising the step of working said metal member on which said electromagnetic wave absorbing member has been formed, to form a shield case for shielding the circuit.
US09/292,833 1998-04-27 1999-04-16 Apparatus and method for shielding electromagnetic wave Expired - Fee Related US6426457B1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040001299A1 (en) * 2001-12-14 2004-01-01 Laird Technologies, Inc. EMI shield including a lossy medium
WO2005055321A2 (en) * 2003-12-04 2005-06-16 Qinetiq Limited Electronical circuit package with cavity resonance cut off member
US20050257370A1 (en) * 2003-06-30 2005-11-24 Nokia Corporation Electromagnetic interference shield and method of making the same
US20060141555A1 (en) * 2002-11-19 2006-06-29 C-Tech Innovation Limited Control of biocatalysis reactions
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US10978790B2 (en) * 2017-09-12 2021-04-13 Mark P Kramer Electromagnetic radiation attenuating device for laptop computers

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE520785C2 (en) * 2000-05-22 2003-08-26 Ericsson Telefon Ab L M Cover for an electronic device
DE10026353A1 (en) * 2000-05-27 2001-11-29 Mannesmann Vdo Ag Shielded electronic circuit
KR100363688B1 (en) * 2000-07-28 2002-12-05 이형주 Blocking Device of Electromagnetic Wave Radiation
DE102005034166A1 (en) * 2005-07-21 2007-02-01 Osram Opto Semiconductors Gmbh Housing for an electromagnetic radiation-emitting optoelectronic component, electromagnetic radiation-emitting component and method for producing a housing or a component
TW200803067A (en) * 2006-06-16 2008-01-01 Inventec Corp Connector structure
KR100829754B1 (en) * 2007-03-02 2008-05-15 삼성에스디아이 주식회사 Structure of combining a chassis with a circuit board and display apparatus comprising the same
WO2009008525A1 (en) * 2007-07-12 2009-01-15 Imagineering, Inc. Exhaust gas substance purifier
US20090290319A1 (en) * 2008-05-20 2009-11-26 Apple Inc. Electromagnetic shielding in small-form-factor device

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4684020A (en) * 1985-09-20 1987-08-04 Conductive Container, Inc. Conductive container
JPH0719995B2 (en) * 1987-04-24 1995-03-06 日本ピラ−工業株式会社 Electromagnetic shield material
US4848566A (en) * 1987-10-23 1989-07-18 W. R. Grace & Co. Antistatic/conductive container
JPH01155691A (en) * 1987-12-14 1989-06-19 Yokohama Rubber Co Ltd:The Radio wave absorbing composite material
JPH0824227B2 (en) * 1990-10-20 1996-03-06 富士通株式会社 Case structure
JP3011378B2 (en) * 1991-07-16 2000-02-21 北川工業株式会社 Electromagnetic shielding composite material
JP2641359B2 (en) * 1991-08-31 1997-08-13 富士通株式会社 Frame structure of communication device
JP3097343B2 (en) * 1992-08-04 2000-10-10 ティーディーケイ株式会社 Thin radio wave absorber
US5700342A (en) * 1993-06-30 1997-12-23 Simmonds Precision Products Inc. Composite enclosure for electronic hardware
JPH0818265A (en) * 1994-06-29 1996-01-19 Molex Inc Method of shielding electromagnetic wave, etc. on printed circuit board and shield cover therefor
JP3215656B2 (en) * 1997-09-01 2001-10-09 栖二 元島 Method and apparatus for producing coiled carbon fiber

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US7135643B2 (en) 2001-12-14 2006-11-14 Laird Technologies, Inc. EMI shield including a lossy medium
US20060141555A1 (en) * 2002-11-19 2006-06-29 C-Tech Innovation Limited Control of biocatalysis reactions
US20050257370A1 (en) * 2003-06-30 2005-11-24 Nokia Corporation Electromagnetic interference shield and method of making the same
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US7820919B2 (en) 2003-12-04 2010-10-26 Qinetiq Limited Electronic circuit packages
US7310067B1 (en) 2006-05-23 2007-12-18 Research In Motion Limited Mobile wireless communications device with reduced interfering RF energy into RF metal shield secured on circuit board
US20080007475A1 (en) * 2006-05-23 2008-01-10 Research In Motion Limited Mobile wireless communications device with reduced interfering rf energy into rf metal shield secured on circuit board
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