GB2227033A - A strip or sheet of electromagnetic-shielding material - Google Patents

A strip or sheet of electromagnetic-shielding material Download PDF

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Publication number
GB2227033A
GB2227033A GB9000423A GB9000423A GB2227033A GB 2227033 A GB2227033 A GB 2227033A GB 9000423 A GB9000423 A GB 9000423A GB 9000423 A GB9000423 A GB 9000423A GB 2227033 A GB2227033 A GB 2227033A
Authority
GB
United Kingdom
Prior art keywords
electromagnetic
shielding material
strip
sheet
conductive particles
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
GB9000423A
Other versions
GB9000423D0 (en
Inventor
Asaharu Nakagawa
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kitagawa Industries Co Ltd
Original Assignee
Kitagawa Industries Co Ltd
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 Kitagawa Industries Co Ltd filed Critical Kitagawa Industries Co Ltd
Publication of GB9000423D0 publication Critical patent/GB9000423D0/en
Publication of GB2227033A publication Critical patent/GB2227033A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B11/00—Communication cables or conductors
    • H01B11/02—Cables with twisted pairs or quads
    • H01B11/06—Cables with twisted pairs or quads with means for reducing effects of electromagnetic or electrostatic disturbances, e.g. screens
    • H01B11/10—Screens specially adapted for reducing interference from external sources
    • H01B11/1025—Screens specially adapted for reducing interference from external sources composed of a helicoidally wound tape-conductor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B11/00—Communication cables or conductors
    • H01B11/02—Cables with twisted pairs or quads
    • H01B11/06—Cables with twisted pairs or quads with means for reducing effects of electromagnetic or electrostatic disturbances, e.g. screens
    • H01B11/10—Screens specially adapted for reducing interference from external sources
    • H01B11/1008—Features relating to screening tape per se

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
  • Communication Cables (AREA)
  • Conductive Materials (AREA)

Description

- 1. 11 1 1 ( 1 1 A STRIP OR SHEET OF ELECTROMAGNETIC-SHIELDING MATERIAL
This invention relates to a strip or sheet of an electromagnetic-shielding material for protecting electronic components from electromagnetic waves. The invention also relates to a process for manufacturing such a sheet or strip of material.
When electromagnetic noise leaks through gaps in the housing of electronic components or is transmitted through signal conductors to the other electronic components, the electronic components may malfunction. The electromagnetic noise from the electronic components in the housing may damage equipment outside.
To avoid trouble caused by electromagnetic waves, a strip or sheet of electromagnetic- shielding material consisting of elastomer containing conductive metallic particles or carbon black as a conductive filler is generally used.
The gaps in the housing of electronic components are covered by the electromagnetic-shielding material or the electromagn e t ic- shielding material is wound around the signal conductors. The electromagnetic-shielding material applied in this way reflects or absorbs electromagnetic noise which is generated by the electronic components in the housing, enters the gaps into the housing, or is tansmitted onto the signal conductors. The inside of the housing and the signal conductors are thus shielded from electromagnetic waves outside. 30 However, the related-art electromagnetic-shielding material cannot sufficiently shield the electronic components from electromagnetic waves and has the following problems. The electromagnetic-shielding material should have an electrical resistivity lower than 10 ohmcm. The related-art electromagneticshielding material has high 1 a 2 conductivity because the sheet contains conductive metallic particles or carbon black (referred to hereafter as "conductive particles"). The material also has elasticity because its base material is an elastomer. When the content of the conductive particles is increased to obtain the electrical resistivity of about 10 ohmcm, the elasticity of the base material deteriorates and the material becomes brittle. When the related-art electromagnet ic- shielding material is wound around a flat cable or a signal conductor with a small diameter, the material breaks or cracks at folded portions of the material.
According to the present invention there is provided a sheet or strip of an electromagnetic- shielding material comprising a non-woven fabric with conductive particles fixed thereon.
According to the present invention in another aspect there is provided a process for manufacturing a sheet or strip of an electromagneticshielding material, comprising the steps of:
soaking a non-woven fabric in a solution containing a binder, a solvent, and conductive particles; and allowing the non-woven fabric to dry to evaporate the solvent.
The base material of the electromagnetic-shielding material is a known non-woven fabric manufactured by adhering interlaced fibres. Particles of copper, silver, or other metals or carbon black are added to provide conductivity to the non-woven fabric. Gaps among interlaced fibres in the non-woven fabric preferably have a diameter larger than that of the conductive particles. The conductive particles are retained on the surface of the fibres of the non-woven fabric, without changing properties or construction of the non-woven fabric.
The electromagnetic-shielding material of this 1 ( 1 1 3 invention has flexibility of the non-woven fabric and also has conductivity of the conductive particles retained on the surface of respective fibres of the nonwoven fabric.
By covering components, the electromagneticshielding material containing the conductive particles shields the components from electromagnetic noise.
The type and amount of the conductive particles added to the non-woven fabric determine the conductivity or the electrical resistivity of the electromagneticshielding material.
Specifically, copper particles are first mixed in a solution containing a binder, a solvent and other agents, and the non-woven fabric is soaked in the solution. The soaking time and the concentration of the copper particles in the solution determine the electrical resistivity of the electromagnetic- shielding material.
The copper particles can be added during the manufacture of the non-woven fabric. The solution containing the binder and the copper particles is sprayed over the fabric. The concentration of the copper particles in the solution and the amount of the solution sprayed determine the electrical resistivity of the electromagnetic-shielding material.
Similarly, when other conductive particles such as silver particles or carbon black are used, the concentration of the conductive particles in the solution and the soaking time of the non-woven fabric in the solution determine the electrical resistivity of the electromagnetic- shielding material.
Embodiments of the invention will now be desc-ribed, by way of examples, with reference to the accompanying drawings, in which:- Figure 1A is a perspective view showing one applicaticn of a sheet embodying the present invention; 4 and Figure 1B is a perspective view showing another application of a sheet embodying the present invention.
As shown in Figures 1A and 1B, a strip of an electromagnetic-shielding material 1 can be wound around a flat cable 3 which has eight electric conductors 3a and a multiple-core cable 5 having eight electric conductors 5a.
The strip of electromagnet ic- shielding material 1 can be manufactured as follows:
First, a non-woven fabric is made through know processes such as by adhering nylon fibres to one another. The non-woven fabric is soaked for 0.2 hour in a solution containing a binder, a solvent and other agents to which 10% by volume of silver particles having a diameter of about 0.002 mm are added. Subsequently, the non-woven fabric is dried to evaporate the solvent. The silver particles thus provide conductivity to the non-woven f abric. Specifically, the non-woven fabric 2 has a surface resistivity of 1 ohm/mm By cutting the non-woven fabric " into strips, the strips of electromagnetic-shielding material 1 are obtained.
Alternatively, the silver particles can be applied to the non-woven fabric after it has been cut into strips.
The strip of electromagnet ic- shielding material 1 manufactured as aforementioned is wound around the flat cable 3 which is 1.5 mm thick and 38 mm wide or the multiple-core cable 5 with a diameter of 30 mm as follows.
First, an end of the strip of electromagnetic shielding material 1 is adhered using an adhesive tape or other adhesive materials to the outer periphery of the flat cable 3 or the multiple-core cable 5.
Subsequently, the strip of electromagnetic-shielding material 1 is wound around the flat cable 3 or the multiple-core cable 5 by pulling or tensioning the strip of electromagnetic-shielding material 1 to prevent the strip 1 from crinkling. After winding has been completed, the other end of the strip of electromagnetic-shielding material 1 is adhered onto the flat cable 3 or the multiple-core cable 5 using the adhesive tape or other adhesive materials.
The silver particles provide a low surface resistivity of 1 ohm/mm2 to the electromagneticshielding material 1 wound around the flat cable 3 or the multiple-core cable 5. The electromagneticshielding material 1 reflects and absorbs electromagnetic noise, and thus protects the electric conductors 3a and 5a, respectively, of the cables 3 and 5 from electromagnetic waves outside. Consequently, no electromagnetic noise is transmitted to the electrical conductors 3a and 5a, respectively, of the flat cable 3 and the multiple-core cable 5, preventing malfunctions from occurring due to electromagnetic noise.
Since the non-woven fabric provides flexibility to the electromagnetic-shielding material 1, the material 1 can be folded to wind around the 1.5 mm thick flat cable 3 and the multiple-core cable 5 with a diameter of 30 mm with no cracks on folded portions of the material 1. When the electromagnet ic- shielding material 1 is folded around the flat cable 3 and the multiple-core cable 5 for a long time, no cracks can be seen or no changes in the electrical resistivity of the material 1 can be seen. The e lectromagne tic- shielding material 1 can be wound again onto another flat cable or another multiplecore cable.
As shown in Figures 1A and 1B, the strip of electromagnetic-shielding material 1 protects the surfaces of the flat cable 3 and the multiplecore cable 5 from scratches or corrosion.
The shielding material 1 can be wound in layers onto the cables.
1 1 6 Although a specific embodiment of the invention has been described for the purpose of illustration, the invention is not limited to the described embodiment. The invention includes all embodiments and modifications that fall within the scope of the appended claims. For example, the adhesive can be applied completely or partially to one side of the electromagnetic-shielding material 1 or peelable paper can be placed onto the side coated with the adhesive, and removed before winding the strip of electromagnetic-shielding materi-al 1 around the cable. The electromagnetic-shielding material 1 can be used as a package for wrapping a printed circuit board equipped with IC and LSI circuit to protect the circuit board from static electricity caused by vibration and impact when the circuit board is conveyed.
j ( r I 1 7

Claims (13)

1. A sheet or strip of an electromagnetic- shielding material comprising a non-woven fabric with conductive particles fixed thereon.
2. A sheet or strip of electromagnetic-shielding material as claimed in claim 1, in which the conductive particles are chosen from the group of conductive particles consisting of metal particles and carbon black.
3. A sheet or strip of electromagnetic-shielding material as claimed in claim 1 or claim 2, in which the conductive particles are fixed on the non-woven fabric by soaking the non- woven fabric in a solution containing a binder, a solvent, and the conductive particles and allowing the solvent to evaporate.
4. A sheet of electromagnetic- shielding material as claimed in claim 3, in which the solution contains 10% by volume of silver particles having an average diameter of 0.002 mm.
5. A sheet or strip of electromagnetic-shielding material as claimed in any preceding claim, further comprising adhesive means provided on one side of the sheet or strip of electromagnetic-shielding material for adhering the sheet or strip to a surface..
6. A sheet or strip of electromagnetic-shielding material as claimed in any preceding claim, in which the electromagnetic-shielding material is formed into an envelope for containing an electronic part.
a a 6 8
7. A process for manufacturing a sheet or strip of an electromagnetic- shielding-material, comprising the steps of:
soaking a non-woven f abric in a solution containing a binder, a solvent, and conductive particles; and allowing the non-woven fabric to dry to evaporate the solvent.
8. A process as claimed in claim 7, in which the soaking time and the concentration of conductive particles in the solution are varied to vary the conductivity of the electromagnetic- shielding material.
9. A process as claimed in claim 7 or claim 8, further comprising the step of cutting the electromagnet ic- shielding material into strips so that they may be wound around a cable.
10. A process as claimed in any one of claims 7 to 9, further comprising the step of forming the electromagnetic- shielding material into an envelope for holding an electronic part.
11. A process as claimed in any one of claims 7 to 10, wherein the conductive particles are chosen from the group of conductive particles consisting of metal particles and carbon black.
12. A sheet or strip or an electromagnetic- shielding material substantially as hereinbefore described with reference to the accompanying drawings.
13. A process for manufacturing a sheet or strip of an electromagneticshielding material substantially as hereinbefore described with reference to the accompanying drawings.
Published 1990atThe Patent Office.State House. 6671 Iligh Holborn. LondonWC1R4TP.Furthe.- copies maybe obtainedfrorr The PwentOEicc Sales Branch, St Mary Cray. Orpington. Kent BR5 3RD Printed by Multiplex techniques ltd. St Mary Cray. Kent. Con. 187
GB9000423A 1989-01-12 1990-01-09 A strip or sheet of electromagnetic-shielding material Withdrawn GB2227033A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP247289U JPH0292997U (en) 1989-01-12 1989-01-12

Publications (2)

Publication Number Publication Date
GB9000423D0 GB9000423D0 (en) 1990-03-07
GB2227033A true GB2227033A (en) 1990-07-18

Family

ID=11530265

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9000423A Withdrawn GB2227033A (en) 1989-01-12 1990-01-09 A strip or sheet of electromagnetic-shielding material

Country Status (3)

Country Link
JP (1) JPH0292997U (en)
DE (2) DE8915264U1 (en)
GB (1) GB2227033A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994002949A1 (en) * 1992-07-15 1994-02-03 W.L. Gore & Associates, Inc. Signal cable having metal-plated polymer shielding
US5455383A (en) * 1993-01-26 1995-10-03 Sumitomo Electric Industries, Ltd. Shield flat cable
WO2000041190A1 (en) * 1998-12-30 2000-07-13 Square D Company Winding transient suppression technique
WO2013138284A3 (en) * 2012-03-13 2013-12-19 Cable Components Group Llc Compositions, methods, and devices providing shielding in communications cables
US9245669B2 (en) 2004-11-06 2016-01-26 Cable Components Group, Llc High performance support-separators for communications cables providing shielding for minimizing alien crosstalk

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102012018055A1 (en) 2012-09-13 2014-03-13 Daimler Ag Sealing of an electrical and / or electronic components receiving housing
DE102019110878B4 (en) * 2019-04-26 2023-12-07 Leoni Kabel Gmbh Combination cable for electrical energy and data transmission
DE202021106822U1 (en) 2021-12-15 2022-01-10 Certoplast Technische Klebebänder Gmbh Electromagnetically shielding cable wrapping tape

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1365895A (en) * 1972-06-21 1974-09-04 Pirelli General Cable Works Electric cable semiconducting sheet material
GB1417394A (en) * 1971-10-18 1975-12-10 Ici Ltd Conductive textile materials
GB1459590A (en) * 1973-04-06 1976-12-22 Filzfabrik Fulda Gmbh Electrically-conductive gas filter medium
GB1565696A (en) * 1975-09-17 1980-04-23 Westinghouse Electric Corp Semiconducting tape
GB2096194A (en) * 1981-04-03 1982-10-13 Lantor Uk Ltd Non-woven electrically conductive sheet material

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE8613035U1 (en) * 1986-05-14 1986-07-24 The Zippertubing Co., Los Angeles, Calif. Shielding jacket for cabling

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1417394A (en) * 1971-10-18 1975-12-10 Ici Ltd Conductive textile materials
GB1365895A (en) * 1972-06-21 1974-09-04 Pirelli General Cable Works Electric cable semiconducting sheet material
GB1459590A (en) * 1973-04-06 1976-12-22 Filzfabrik Fulda Gmbh Electrically-conductive gas filter medium
GB1565696A (en) * 1975-09-17 1980-04-23 Westinghouse Electric Corp Semiconducting tape
GB2096194A (en) * 1981-04-03 1982-10-13 Lantor Uk Ltd Non-woven electrically conductive sheet material

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994002949A1 (en) * 1992-07-15 1994-02-03 W.L. Gore & Associates, Inc. Signal cable having metal-plated polymer shielding
US5455383A (en) * 1993-01-26 1995-10-03 Sumitomo Electric Industries, Ltd. Shield flat cable
WO2000041190A1 (en) * 1998-12-30 2000-07-13 Square D Company Winding transient suppression technique
US9245669B2 (en) 2004-11-06 2016-01-26 Cable Components Group, Llc High performance support-separators for communications cables providing shielding for minimizing alien crosstalk
US10204719B2 (en) 2004-11-06 2019-02-12 Cable Components Group, Llc High performance support-separators for communications cables providing shielding for minimizing alien crosstalk
US10204720B2 (en) 2004-11-06 2019-02-12 Cable Components Group, Llc High performance support-separators for communications cables providing shielding for minimizing alien crosstalk
WO2013138284A3 (en) * 2012-03-13 2013-12-19 Cable Components Group Llc Compositions, methods, and devices providing shielding in communications cables
US9711261B2 (en) 2012-03-13 2017-07-18 Cable Components Group, Llc Compositions, methods, and devices providing shielding in communications cables
US9875825B2 (en) 2012-03-13 2018-01-23 Cable Components Group, Llc Compositions, methods and devices providing shielding in communications cables

Also Published As

Publication number Publication date
GB9000423D0 (en) 1990-03-07
DE3943295C2 (en) 2000-01-05
DE3943295A1 (en) 1990-07-19
DE8915264U1 (en) 1990-03-22
JPH0292997U (en) 1990-07-24

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)