Shielded communication cable

Abstract

Shielded communication cable (1, 2) with: a twisted pair of conductors (10) comprising intertwined insulated wires (11), each of which comprises: a conductor (12) with a tensile strength of 400 MPa or more; and an insulating coating (13) that surrounds the conductor (12); and a shield (20) made of a conductive material and surrounding the twisted pair of conductors (10), wherein the shielded communication cable (1, 2) has a characteristic impedance of 100 ± 10 Ω, Each of the insulated wires (11) has a conductor cross-sectional area of ​​0.08 mm² 2 or more and less than 0.22 mm 2 exhibits and the insulating coating (13) of each of the insulated wires (11) has a thickness of 0.20 mm or more and 0.35 mm or less.

Description

TECHNICAL AREA

[0001] The present invention relates to a shielded communication cable and, in particular, a shielded communication cable that can be used for high-speed communication, for example in a vehicle. TECHNICAL BACKGROUND

[0002] There is a growing need for high-speed communication, for example in the field of automotive technology. The transmission characteristics of a cable used for high-speed communication, such as its characteristic impedance, must be reliably set. For example, the characteristic impedance of a cable used for Ethernet communication must be within 100 ± 10 Ω.

[0003] The characteristic impedance of a cable depends on its specific features, such as the diameter of a conductor and the type and thickness of an insulating coating. For example, Patent Document 1 discloses a shielded communication cable comprising a twisted pair of conductors with two insulated cores twisted together, each insulated core comprising a conductor and insulation surrounding the conductor. The cable further comprises a metal foil shield enclosing the twisted pair, a grounding wire electrically connected to the shield, and a jacket enclosing the twisted pair, the grounding wire, and the shield. The cable has a characteristic impedance of 100 ± 10 Ω. In the insulated cores used in Patent Document 1, each conductor has a diameter of 0.55 mm, and the insulation surrounding the conductor has a thickness of 0.35 to 0.45 mm.

[0004] Patent document 2 discloses an unshielded communication cable with a twisted pair of conductors, the conductors of which have a tensile strength of 650 N / mm². 2 or more, a conductor cross-section of 0.10 to 0.25 mm² 2 and have a dielectric coating with a thickness of 0.20 ± - 0.05 mm. The characteristic impedance of the unshielded cable is 100 ± 10 Ω.

[0005] Patent document 3 discloses a shielded communication cable with a twisted pair of conductors, the conductors of which have a conductor cross-section of 20 to 30 AWG (0.05 mm²). 2 up to 0.52 mm 2 ), and have an insulating coating with a thickness of 0.010 to 0.060 inches (0.254 to 1.52 mm). The characteristic impedance of the shielded cable is close to 100 Ω.

[0006] Patent document 4 discloses a method for manufacturing a communication cable with a twisted pair of conductors. The conductors have a cross-sectional area of ​​18 to 40 AWG (0.005 mm²). 2 up to 0.82 mm 2 ) and an insulating coating with a thickness of 0.006 mm to 3.81 mm. The cable has an impedance in the range of 100 Ω. PREVIOUSLY KNOWN TECHNICAL DOCUMENTS PATENT DOCUMENTS Patent document 1: JP 2005 - 32 583 A Patent Document 2: CN 2 04 792 164 U Patent document 3: US 6,686,537 B1 Patent document 4: EP 0 689 715 B1 OVERVIEW OF THE INVENTION TASK TO BE SOLVED BY THE INVENTION

[0007] There is a significant need to reduce the diameter of communication cables, such as those used in vehicles. To meet this need, the size of the shielded communication cable must be reduced while maintaining the required transmission characteristics, including the characteristic impedance. One possible method for reducing the diameter of a shielded communication cable with a twisted pair is to thin the insulating coatings on the insulated wires that make up the twisted pair. However, if the insulation thickness of the communication cable disclosed in patent document 1 is reduced to less than 0.35 mm, the inventors' investigation shows that the characteristic impedance falls below 90 Ω. This is outside the range of 100 ± 10 Ω required for Ethernet communication.

[0008] One object of the present invention is to provide a shielded communication cable that has a reduced diameter while simultaneously ensuring a required amount of characteristic impedance. SOLUTION TO THE TASK

[0009] The problem is solved by a shielded communication cable according to the present invention, comprising a twisted pair of conductors with two insulated, twisted wires. Each of the insulated wires comprises a conductor with a tensile strength of 400 MPa or higher and an insulating coating enclosing the conductor. The shielded communication cable includes a shield made of a conductive material surrounding the twisted pair of conductors. The shielded communication cable has a characteristic impedance of 100 ± 10 Ω. Each of the insulated wires has a conductor cross-sectional area of ​​0.08 mm². 2or more and less than 0.22 mm 2 The insulating coating of each of the insulated wires has a thickness of 0.20 mm or more, preferably 0.30 mm or more, and 0.35 mm or less.

[0010] Preferably, each of the insulated wires has an outer diameter of 1.15 mm or less. Preferably, the conductor of each of the insulated wires has an elongation at break of 7% or more.

[0011] Preferably, the shielding is a braided shield. Otherwise, the shielding is preferably a metal foil shield, and the cable further comprises a grounding wire within an area surrounded by the shielding, which is electrically connected to the shielding. EFFECT OF INVENTION

[0012] Since the conductor of each of the insulated wires forming the twisted pair in the aforementioned shielded communication cable exhibits a high tensile strength of 400 MPa or more, the conductor diameter can be reduced while simultaneously ensuring the required strength for an electrical wire. Therefore, the distance between the two conductors forming the twisted pair is reduced, which may increase the characteristic impedance of the shielded communication cable. As a result, the characteristic impedance of the shielded communication cable can be maintained within the range of 100 ± 10 Ω and will not fall below this range even if the insulating coating of each insulated conductor is made thin to reduce the diameter of the shielded communication cable.

[0013] If each of the insulated wires has a conductor cross-sectional area of ​​less than 0.22 m² 2 The characteristic impedance of the communication cable is increased due to the effect of reducing the distance between the two insulated wires that make up the twisted pair. Reducing the thickness of the insulating coating facilitates a reduction in the diameter of the shielded communication cable while simultaneously ensuring the required characteristic impedance. Furthermore, the small diameter of each conductor allows for a reduction in the overall diameter of the shielded communication cable.

[0014] If the insulating coating of each of the insulated wires has a thickness of 0.35 mm or less, the diameter of each of the insulated wires is sufficiently small, thus efficiently reducing the diameter of the entire shielded communication cable.

[0015] Even if each of the insulated wires has an outer diameter of 1.15 mm or less, the diameter of the entire shielded communication cable can be efficiently reduced.

[0016] If the conductor of each of the insulated wires has an elongation at break of 7% or higher, the conductor has high impact resistance, which means that the conductor can withstand the shocks acting upon it well when a cable harness is made from the shielded communication cable or when the cable harness is installed.

[0017] If the shielding is formed by the braided shielding material, the shielded communication cable does not require a grounding wire because the braided shielding can be grounded directly. Therefore, the shielded communication cable can have a simple structure and a reduced diameter.

[0018] If the shielding is made of metal foil and the cable furthermore has the grounding wire within the area surrounded by the shielding, which is electrically connected to the shielding, the diameter of the shielded communication cable can be efficiently reduced by the small thickness of the metal foil shielding. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a cross-sectional view showing a shielded communication cable according to a first embodiment of the present invention. Fig.Figure 2 is a cross-sectional view showing a shielded communication cable according to a second embodiment of the present invention. DESCRIPTION OF THE EXECUTION FORMS

[0019] A shielded communication cable according to a preferred embodiment of the present invention is described in detail below. First embodiment

[0020] Fig. Figure 1 shows a cross-sectional view of the shielded communication cable according to the first embodiment of the present invention.

[0021] The shielded communication cable 1 comprises a twisted pair of conductors, each consisting of two insulated wires 11, 11, which are twisted together. Each of the insulated wires 11 comprises a conductor 12 and an insulating coating 13 that surrounds the conductor 12 on its outer surface. The shielded communication cable further comprises a braided shield 20 made of a conductive material, which surrounds the twisted pair of conductors 10. The communication cable 1 also includes a sheath 30 made of an insulating material, which encloses the braided shield 20 provided on an outer circumference of the twisted pair of conductors 10.

[0022] The shielded communication cable 1 has a characteristic impedance of 100 ± 10 Ω. A characteristic impedance of 100 ± 10 Ω is required for a cable used for Ethernet communication. With this required characteristic impedance, the shielded communication cable 1 is suitable for high-speed communication, such as in a vehicle.

[0023] The conductors 12 of the insulated wires 11, which form the twisted pair 10, are metal wires having a tensile strength of 400 MPa or higher. Specific examples of the metal wires, illustrated below, are copper alloy wires containing iron and titanium. The tensile strength of the conductors 12 is preferably 440 MPa or higher and particularly preferably 480 MPa or higher.

[0024] Because the conductors 12 have a tensile strength of 400 MPa or higher, they can maintain the tensile strength required for electrical conductors even if their diameter is reduced. When the diameter of the conductors 12 is reduced, the distance between the two conductors 12, 12 that form the twisted pair is reduced (i.e., the length of the line connecting the centers of conductors 12, 12 is reduced), which increases the characteristic impedance of the shielded communication cable 1. For example, the diameter of the conductors 12 can be so small that the conductor cross-sectional area is less than 0.2 mm². 2 results, and particularly preferably a conductor cross-sectional area of ​​0.15 m² 2 or smaller, or of 0.13 mm 2or smaller. The outer diameter of the conductors 12 can be 0.50 mm or smaller. However, if the diameter of the conductors 12 is too small, the conductors 12 may not have sufficient strength, and the characteristic impedance of the communication cable 1 may be too high. Therefore, the cross-sectional area of ​​the conductors 12 is preferably 0.08 mm². 2 or larger.

[0025] If the conductors 12 have a small conductor cross-sectional area that is less than 0.22 mm² 2 Therefore, a characteristic impedance of 100 ± 10 Ω can be reliably ensured for the shielded communication cable, even if the thickness of the insulating coatings 13 enclosing the conductors 12 is reduced, for example to 0.35 mm or less. Conventional electrical copper wires with a conductor cross-sectional area of ​​less than 0.22 mm² 2 They are difficult to use because the wires have a lower tensile strength.

[0026] Preferably, the conductors 12 have an elongation at break of 7% or higher. Generally, a conductor with high tensile strength has low toughness and therefore exhibits low impact resistance when a force is rapidly applied to the conductor. However, if the aforementioned conductors 12, with a tensile strength of 400 MPa or higher, have an elongation at break of 7% or higher, they exhibit excellent resistance to impacts exerted on them when a cable harness is manufactured from the communication cable or when the cable harness is installed.

[0027] The conductors 12 can each consist of individual wires; however, for high flexibility, the conductors 12 preferably consist of a wire strand comprising several individual wires twisted together. In this case, the conductors 12 can be pressed strands formed by compressing the wire strand after the individual wires have been twisted together. The outer diameter of the conductors 12 can be reduced by this compression. Furthermore, the wire strands 12 can consist of a single type of individual wire or of two or more types of individual wires, provided that the conductors 12 as a whole each have a tensile strength of 400 MPa or higher.Examples of conductors consisting of two or more types of single wires 12 are conductors comprising Fe- and Ti-containing copper alloy wires as described below and further comprising single wires made of a metallic material other than a copper alloy, such as SUS.

[0028] The insulating coatings 13 of the insulated wires 11 can be made of any type of polymer material. Preferably, the insulating coatings 13 have a relative dielectric constant of 4.0 or less to ensure the required high characteristic impedance. Examples of polymer materials exhibiting this relative dielectric constant are polyolefins, such as polyethylene and polypropylene, polyvinyl chloride, polystyrene, polytetrafluoroethylene, and polyphenylene sulfide. Furthermore, the insulating coatings 13 can contain additional additives besides the polymer material, such as a flame retardant.

[0029] By reducing the diameter of the conductors 12 and consequently arranging the two conductors 12, 12 closer together, the characteristic impedance of the shielded communication cable 1 is increased. As a result, the thickness of the insulating coatings 13 required to ensure the desired characteristic impedance can be reduced. For example, the thickness of the insulating coatings 13 is preferably 0.35 mm or less, more preferably 0.3 mm or less, and most preferably 0.25 mm or less. However, if the insulating coatings 13 are too thin, it can be difficult to ensure the required characteristic impedance. Therefore, the thickness of the insulating coatings 13 is preferably 0.20 mm or more.

[0030] By reducing the diameter of the conductors 12 and the thickness of the insulating coatings 13, the overall diameter of the insulated wires 11 is reduced. The outer diameter of the insulated wires 11 can be, for example, 1.15 mm or less, and particularly preferably 1.05 mm or less. Reducing the diameter of the insulated wires 11 serves to reduce the overall diameter of the communication cable 1.

[0031] The shielding braid 20 is made of thin metallic individual wires woven in the form of a hollow cylinder. The individual wires are made of a metallic material, such as copper, a copper alloy, aluminum, or an aluminum alloy, or of a material having a plated layer on the surface of the metallic material. The shielding braid 20 serves to shield the twisted pair of conductors 10 from external interference and to block interference emitted by the twisted pair of conductors 10. The design of the shielding braid 20 (such as the number of plies, the number of wires per ply, and the lay length) can be selected according to the required shielding properties.

[0032] The sheath 30, like the insulating coatings 13 of the insulated wires, can be made of any polymer material. Examples of polymer materials include polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polystyrene, polytetrafluoroethylene, and polyphenylene sulfide. Depending on requirements, the sheath 30 may contain additives in addition to the polymer material, such as a flame retardant. The sheath 30 serves to protect the shielding braid 20 and to maintain the twisted structure of the twisted pair. However, the sheath 30 is not strictly necessary for the communication cable 1; it can be omitted if no problems arise from its absence.

[0033] As previously described, since the conductors 12 of the insulated wires 11 forming the twisted pair have a tensile strength of 400 MPa or higher, sufficient strength of the communication cable 1 for use in a vehicle can be better ensured even if the diameter of the conductors 12 is reduced. When the conductors 12 have a reduced diameter, the distance between the two conductors 12, 12 in the twisted pair 10 is reduced. When the distance between the two conductors 12, 12 is reduced, the characteristic impedance of the shielded communication cable 1 is increased.If the insulated wires 11 forming the twisted pair have thinner insulating coatings 13, the shielded communication cable 1 has a lower characteristic impedance; however, in the present embodiment, the reduced distance between the conductors 12, 12, achieved by their reduced diameter, can ensure the characteristic impedance of 100 ± 10 Ω of the shielded communication cable 1 even with a small thickness of the insulating coating 13 of, for example, 0.35 mm or less.

[0034] Making the insulating coatings 13 of the insulated conductors 11 thinner leads to a reduction in the diameter (i.e., the final diameter) of the shielded communication cable 1 as a whole. The shielded communication cable 1, which has the reduced diameter and can simultaneously ensure the required characteristic impedance, can be used effectively for high-speed communication within a limited installation space, such as in a vehicle.

[0035] In the second embodiment, shown next, a metal foil shield 40 is used instead of the braided shield 20, which is made of a conductive material. The thickness of the shield tends to be greater when the braided shield 20 is used, as in the present first embodiment, than when the metal foil shield 40 is used. However, the braided shield 20 can be directly grounded by expanding it, whereas the metal foil shield 40 cannot be directly grounded and therefore requires a grounding wire 50. The grounding wire 50 can be omitted when the braided shield 20 is used. The overall structure of the shielded communication cable 1 is simplified by omitting the grounding wire 50, which allows the diameter of the entire shielded communication cable 1 to be reduced. Second embodiment

[0036] Fig. Figure 2 shows a cross-sectional view of the communication cable 2 according to the second embodiment of the present invention.

[0037] According to the second embodiment, the shielded communication cable 2 has a metal foil shield 40 instead of the braided shield 20 of the shielded communication cable 1 as described above. The shielded communication cable 2 further comprises, within the area surrounded by the metal foil shield 40, a grounding wire 50 together with the twisted pair of conductors 10. The shielded communication cable 2 has the same structure as the shielded communication cable 1 as described above, except that the cable 2 has the metal foil shield 40 and the grounding wire 50; the explanation of the structure is omitted.

[0038] The metal foil shield 40 is a foil made of a material such as copper, a copper alloy, aluminum, or an aluminum alloy. The metal foil surrounds both the twisted pair of conductors 10 and the grounding wire 50. The thickness of the metal foil shield 40 can be selected according to the required shielding properties.

[0039] The grounding wire 50 is made of electrically conductive wire or wires. The grounding wire 50 is twisted with the two insulated wires 11, 11 in the twisted pair of conductors 10 or can run along the twisted pair of conductors 10. The individual wire or wires forming the grounding wire 50 are made of a metallic material, such as copper, a copper alloy, aluminum, or an aluminum alloy, or of a material having a plated layer, such as a tinned layer, on the surface of the metallic material. The grounding conductor 50 can consist of a single wire, but preferably, with regard to sufficient strength, the grounding conductor 50 consists of a twisted wire with several individual wires twisted together.

[0040] The grounding wire 50 is in contact with the metal foil shield 40 and is electrically connected to it. When the shielded communication cable 2 is used, the metal foil shield 40 can be grounded via the grounding wire 50.

[0041] The metal foil shield 40 has a smaller thickness and can be positioned closer to the twisted pair of conductors 10 than the braided shield 20 of the shielded communication cable 1 according to the first embodiment. Therefore, the overall diameter of the shielded communication cable 2 can be reduced more efficiently by incorporating the metal foil shield 40 instead of the braided shield 20. Ladder material

[0042] Specific examples of the copper alloy wires that can be used as conductors 12 of the insulated wires 11 in the shielded communication cable 1 according to the aforementioned first and second embodiments are described below.

[0043] Copper alloy wires of the first and second embodiments have the following composition: Fe: 0.05 wt.% or more and 2.0 wt.% or less; Ti: 0.02 wt.% or more and 1.0 wt.% or less; Mg: 0 wt.% or more and 0.6 wt.% or less (including a case where the alloy contains no Mg); and for the material balance, copper and unavoidable impurities.

[0044] The copper alloy wires with the aforementioned composition exhibit very high tensile strength. In particular, especially high tensile strength is achieved when the copper alloy wires contain 0.8 wt.% or more Fe, or 0.2 wt.% or more Ti. Furthermore, the tensile strength of the wires can be further improved by reducing the wire diameter by increasing the drawing ratio, or by subjecting the wires to heat treatment after drawing. In this way, conductors 12 exhibiting a tensile strength of 400 MPa or higher can be obtained. EXAMPLES

[0045] The present invention will now be described in detail with reference to examples, however, the present invention is not limited to these examples. Preparation of samples(1) Preparation of a conductor

[0046] In each of the examples, a conductor for the insulated wires was fabricated. Specifically, electrolytic copper with a purity of 99.99% or higher, as well as master alloys containing iron and titanium, were placed in a crucible made of high-purity carbon and vacuum-melted to provide a molten metal mixture containing 1.0 wt% Fe and 0.4 wt% Ti. The molten metal mixture was continuously poured into a casting with a diameter of 12.5 mm. The casting was extruded and selected to a diameter of 8 mm and then drawn into a single wire with a diameter of 0.165 mm. Seven single wires produced in this manner were stranded with a lay length of 14 mm, and the stranded wire was compressed. The compressed wire was then subjected to heat treatment, with the wire temperature held at 500°C for 8 hours.In this way, a conductor was produced which has a cross-sectional area of ​​0.13 mm. 2 and has an outer diameter of 0.45 mm.

[0047] The tensile strength and elongation at break of the copper alloy conductor produced in this manner were evaluated according to JISZ2241. For the evaluation, the distance between the evaluation points was set at 250 mm, and the tensile speed was set at 50 mm / min. According to the evaluation results, the copper alloy conductor exhibited a tensile strength of 490 MPa and an elongation at break of 8%.

[0048] For comparative purposes, conventional stranded wire made of pure copper was used as the conductor. The tensile strength, elongation at break, cross-sectional area, and outer diameter of the conductors were measured in the same manner as described above and are shown in Tables 1 and 2. The cross-sectional area and outer diameter values ​​chosen for the conductors can essentially be considered lower limits for an electrical wire made of pure copper, with these lower limits resulting from the limited strength of the conductors. (2) Production of insulated wires

[0049] Insulated wires were produced by forming, via extrusion, insulating coatings of polyethylene resin around conductors made of copper alloy and pure copper as described above. The thicknesses of the insulating coatings for the individual examples and comparative examples are shown in Tables 1 and 2. (3) Manufacture of shielded communication cables with braided shielding.

[0050] In examples A1 to A4 and comparison examples A1 and A2, two insulated wires produced as described above with a stranding length of 25 mm were twisted together to provide a twisted pair of conductors.

[0051] The twisted conductors were then surrounded with braided shielding. The braided shielding was made from tinned, annealed copper wires with a diameter of 0.12 mm (i.e., 0.12TA – stress-relieved annealing). The number of plies, the number of wires per ply, and the lay length were selected as shown in Table 1. Sheaths were then formed around the braided shielding by extruding a polyethylene resin. The sheaths have a thickness of 0.4 mm. This completed the shielded communication cables of examples A1 to A4 and the comparison examples A1 and A2. (4) Manufacture of shielded communication cables with metal foil shielding

[0052] For examples B1 to B4 and comparison examples B1 and B2, a conductive wire was manufactured as a grounding wire by twisting together nine tinned copper strands with a diameter of 0.18 mm. Two insulated wires, manufactured as described above, were twisted together with the grounding wire, with a lay length of 25 mm, to form twisted pairs. These twisted pairs were then enclosed in metal foil shields. Aluminum foil with a thickness of 0.05 mm was used for the metal foil shields. Sheaths with a thickness of 0.4 mm were formed by extruding a polyethylene resin around the metal foil shields. In this way, the shielded communication cables of examples B1 to B4 and comparison examples B1 and B2 were manufactured. Evaluation of finished outer diameter

[0053] To evaluate whether the cable diameters had been successfully reduced, the outer diameters of the manufactured communication cables were measured. Wave resistance

[0054] The characteristic impedances of the manufactured communication cables were measured. The measurement was performed using an LCR meter, with the cable end electrically open in one case and electrically short-circuited in the other. Results

[0055] Table 1 shows the configurations and evaluation results of the shielded communication cables with the braided shielding of examples A1 to A4 and the comparison examples A1 and A2. Table 2 shows the configurations and evaluation results of the shielded communication cables with the metal foil shielding of examples B1 to B4 and the comparison examples B1 and B2. Table 1 Insulated wires shielding mesh Final outer diameter [mm] Impedance [Ω] Director Thickness of insulating coating [mm] Outer diameter [mm] °C °W Stranding length [mm] material Tensile strength [MPa] Elongation[%] Cross-sectional area [mm²] 2 ] Outer diameter [mm] Example A1 copper alloy 490 8 0,13 0,45 0,35 1,15 12 8 25 3,5 109 Example A2 0,30 1,05 7 3,3 101 Example A3 0,25 0,95 7 3,1 94 Example A4 0,20 0,85 6 2,9 90 Comparison example A1 Pure copper 220 24 0,22 0,55 0,35 1,25 12 8 25 3,7 89 Comparison example A2 0,30 1,15 8 3,5 86 *C: Number of compartments *W: Number of wires per strand Table 2 Insulated wires metal foil Final outer diameter [mm] Impedance [Ω] Director Thickness of insulating coating [mm] Outer diameter [mm] material Tensile strength [MPa] Elongation[%] Cross-sectional area [mm²] 2 ] Outer diameter [mm] Example B1 copper alloy 490 8 0,13 0,45 0,35 1,15 Al, 0.05mm (using a grounding wire) 3,2 109 Example B2 0,30 1,05 3,0 102 Example B3 0,25 0,95 2,8 96 Example B4 0,20 0,85 2,6 90 Comparison example B1 Pure copper 220 24 0,22 0,55 0,35 1,25 Al, 0.05mm (Without using a grounding wire) 3,4 90 Comparative example B2 0,30 1,15 3,2 87

[0056] According to Table 1, which shows the evaluation results of the examples for the communication cables with braided shields, examples A1 and A2, which are conductors made of copper alloy with conductor cross-sectional areas smaller than 0.22 mm², exhibit 2 include higher characteristic impedances than the comparison examples A1 and A2, which are conductors made of pure copper with a conductor cross-sectional area of ​​0.22 mm² 2Examples A1 and A2 have the same thickness as the comparison examples A1 and A2, respectively. Examples A1 and A2 each exhibit the characteristic impedances required for Ethernet communication in the range of 100 ± 10 Ω, whereas comparison examples A1 and A2 each have particularly low characteristic impedances outside the range of 100 ± 10 Ω. Examples A3 and A4 each maintain a characteristic impedance in the range of 100 ± 10 Ω, even though the insulating coating is thinner.

[0057] The observed trend in characteristic impedances can be interpreted as a result of the smaller diameter of the copper alloy conductors and the smaller spacing between them compared to conductors made of pure copper. Consequently, the copper alloy conductors can have a thinner insulating coating of less than 0.35 mm while still ensuring characteristic impedances of 100 ± 10 Ω; the thickness can be reduced to a minimum of 0.2 mm. This reduction in insulating coating thickness, like the reduction in conductor diameter, thus serves to reduce the final outer diameter of the shielded communication cable.

[0058] For the cables with metal foil shielding shown in Table 2, when comparing examples B1 to B4 with the comparison examples B1 and B2, the same trend is observed as when comparing the braided shielding cables of examples A1 to A4 with the comparison examples A1 and A2. The cables with metal foil shielding have slightly smaller final outer diameters than the braided shielding cables. This is because the metal foil shields are thinner and can be positioned closer to the twisted pairs than the braided shields.

[0059] In Example B4, where copper alloy wires are used, and in comparison Example B1, where pure copper wires are used, the same characteristic impedance is observed. Comparing the final outer diameters in the two cases, the shielded communication cable according to Example B4 has a 24% smaller outer diameter because the conductor diameter is reduced. LIST OF REFERENCE MARKS 1, 2 communication cables 10 twisted pairs of wires 11 insulated wires 12 ladders 13 insulating coating 20 shielding braid 30 sheathing 40 Shielding made of metal foil

Claims

[1] Shielded communication cable (1, 2) with: a twisted pair of conductors (10) comprising intertwined insulated wires (11), each of which comprises: a conductor (12) with a tensile strength of 400 MPa or more; and an insulating coating (13) that surrounds the conductor (12); and a shield (20) made of a conductive material and surrounding the twisted pair of conductors (10), wherein the shielded communication cable (1, 2) has a characteristic impedance of 100 ± 10 Ω, Each of the insulated wires (11) has a conductor cross-sectional area of ​​0.08 mm² 2 or more and less than 0.22 mm 2 exhibits and the insulating coating (13) of each of the insulated wires (11) has a thickness of 0.20 mm or more and 0.35 mm or less. [2] Shielded communication cable (1, 2) according to claim 1, wherein the insulating coating (13) of each of the insulated wires (11) has a thickness of 0.30 mm or more and 0.35 mm or less. [3] Shielded communication cable (1, 2) according to one of claims 1 to 2, wherein each of the insulated wires (11) has an outer diameter of 1.15 mm or less. [4] Shielded communication cable (1, 2) according to any one of claims 1 to 3, wherein the conductor (12) of each of the insulated wires (11) has an elongation at break of 7% or higher. [5] Shielded communication cable (1) according to any one of claims 1 to 4, wherein the shielding is a shielding braid (20). [6] Shielded communication cable (2) according to any one of claims 1 to 4, wherein the shielding (40) is a shield made of metal foil and the shielded communication cable (2) further comprises within an area surrounded by the shielding (40) an earthing wire (50) which is electrically connected to the shielding (40).

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