Coaxial Cable, Method of Manufacturing the Coaxial Cable, and Cable Assembly

Abstract

The present invention provides a coaxial cable, a method for manufacturing the coaxial cable, and a cable assembly that are difficult to produce a shielding effect reduction and are difficult to produce a sharp attenuation within a predetermined frequency band. The coaxial cable (1) includes: a conductor (2); an insulator (3) covering the periphery of the conductor (2); a shielding layer (4) having a transverse winding shield in which a plurality of metal wires (41) are spirally wound around the periphery of the insulator (3); and a sheath (5) covering the periphery of the shielding layer (4). The insulator (3) has recesses (3a) fitting with the plurality of metal wires (41) on the surface of the portion in contact with the plurality of metal wires (41). The portion of the shielding layer (4) in contact with the insulator (3) in the circumferential direction of the plurality of metal wires (41) fits with the recesses (3a) of the insulator (3), and the plurality of metal wires (41) adjacent to each other in the circumferential direction of the shielding layer (4) are in surface contact with each other.

Description

Technical Field

[0001] The present invention relates to a coaxial cable, a method for manufacturing the coaxial cable, and a cable assembly. Background Art

[0002] As a cable for high-frequency signal transmission used for internal wiring of electronic devices such as imaging devices, smartphones, and tablet terminals used in autonomous driving or the like, or for wiring in machine tools such as industrial robots, a coaxial cable is used.

[0003] As a conventional coaxial cable, there is known a coaxial cable in which a strip member such as a copper tape having a copper foil provided on a resin layer is spirally wound around an insulator to form a shielding layer (for example, see Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2000-285747 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in the above-described conventional coaxial cable, there is a problem called a Suck Out phenomenon in which a sharp attenuation occurs in a predetermined frequency band (for example, a frequency band of several GHz such as 1.25 GHz).

[0009] On the other hand, for example, by forming a shielding layer by electroplating the outer surface of the insulator, the occurrence of suck out can be suppressed. However, when the coaxial cable is repeatedly bent, cracks may occur in the shielding layer formed by electroplating or peeling may occur from the outer surface of the insulator. If cracks occur in the shielding layer formed by electroplating or peeling occurs from the outer surface of the insulator, the shielding effect is reduced. That is, the effect of shielding the noise generated by the coaxial cable using the shielding layer is reduced.

[0010] Therefore, an object of the present invention is to provide a coaxial cable, a method for manufacturing the coaxial cable, and a cable assembly that are less likely to cause a reduction in shielding effect and are less likely to cause a sharp attenuation in a predetermined frequency band.

[0011] Means for Solving the Problems

[0012] The present invention aims to solve the above problems and provides a coaxial cable, comprising: a conductor; an insulator covering the periphery of the conductor; a shielding layer having a laterally wound shield, the laterally wound shield being spirally wound with a plurality of metal wires so as to cover the periphery of the insulator; and a sheath covering the periphery of the shielding layer. The insulator has recesses fitting with the plurality of metal wires on the surface of the portion in contact with the plurality of metal wires. The portion of the shielding layer in contact with the insulator in the circumferential direction of the plurality of metal wires fits with the recesses of the insulator, and the plurality of metal wires adjacent to each other in the circumferential direction of the shielding layer are in surface contact with each other.

[0013] Moreover, the present invention aims to solve the above problems and provides a method for manufacturing a coaxial cable, the coaxial cable comprising: a conductor; an insulator covering the periphery of the conductor; a shielding layer composed of a laterally wound shield, the laterally wound shield being spirally wound with a plurality of metal wires so as to cover the periphery of the insulator; and a sheath covering the periphery of the shielding layer. The method for manufacturing the coaxial cable comprises: a core forming step in which the insulator is coated around the conductor by extrusion molding to form a core; a wire winding step in which a plurality of metal wires are spirally wound around the core; a first heating step in which the core wound with the plurality of metal wires is heated to soften the insulator; a compression step in which the heated plurality of metal wires and the core are passed through a die, and the metal wires are compressed toward the core side, thereby forming recesses fitting with the plurality of metal wires on the surface of the portion of the insulator in contact with the plurality of metal wires, and causing the portions of the plurality of metal wires in contact with the insulator in the circumferential direction to fit with the recesses of the insulator, and causing the plurality of metal wires adjacent to each other in the circumferential direction of the shielding layer to be in surface contact with each other, thereby forming the shielding layer; a second heating step in which the shielding layer is heated to relieve the strain of the metal wires caused by the compression step; and a sheath forming step in which the sheath is coated around the shielding layer by extrusion molding.

[0014] Furthermore, the present invention aims to solve the above problems and provides a cable assembly, comprising: the above coaxial cable; and a terminal component integrally provided at at least one end of the coaxial cable.

[0015] The effects of the invention are as follows.

[0016] According to the present invention, it is possible to provide a coaxial cable, a method for manufacturing a coaxial cable, and a cable assembly in which it is difficult to reduce the shielding effect and it is difficult to generate a sharp attenuation in a predetermined frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. is a view of a coaxial cable showing an embodiment of the present invention. (a) is a cross-sectional view showing a cross-section perpendicular to the longitudinal direction, and (b) is an enlarged view of a main part thereof.

[0018] Figure 2 is a flowchart in manufacturing the coaxial cable.

[0019] Figure 3 is a view for explaining the formation of the shielding layer.

[0020] Figure 4 is a cross-sectional view showing a terminal portion of the cable assembly.

[0021] Figure 5 is a cross-sectional view showing a cross-section perpendicular to the longitudinal direction of the coaxial cable according to one mode of the present invention.

[0022] Figure 6 is a cross-sectional view showing a cross-section perpendicular to the longitudinal direction of a multi-core cable to which the present invention is applied.

[0023] Description of reference signs

[0024] 1 - coaxial cable, 2 - conductor, 3 - insulator, 3a - recess, 4 - shielding layer, 41 - metal wire, 41a - fitting portion, 41b - wire contact portion, 41c - exterior, 42 - electroplating portion together, 5 - sheath, 6 - core portion, 10 - cable assembly, 11 - terminal member. Detailed description of the preferred embodiments

[0025] [Embodiment]

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0027] Figure 1 FIG. is a view of the coaxial cable according to the present embodiment. (a) is a cross-sectional view showing a cross-section perpendicular to the longitudinal direction, and (b) is an enlarged view of a main part thereof.

[0028] As Figure 1 shown in (a) and (b) of, the coaxial cable 1 includes a conductor 2, an insulator 3 provided to cover the periphery of the conductor 2, a shielding layer 4 provided to cover the periphery of the insulator 3, and a sheath 5 provided to cover the periphery of the shielding layer 4.

[0029] The conductor 2 is composed of a stranded conductor formed by stranding a plurality of metal wires 21. However, it is not limited to this. As the conductor 2, a compressed stranded conductor can also be used, which is formed by stranding the metal wires 21 and then compressing and processing them into a circular cross-sectional shape perpendicular to the cable length direction. By using the compressed stranded conductor as the conductor 2, the conductivity can be improved, good transmission characteristics can be obtained, and the ease of bending can also be maintained. Moreover, from the viewpoints of improving conductivity and mechanical strength, the metal wire 21 can also be a copper alloy wire containing tin (Sn), silver (Ag), indium (In), titanium (Ti), magnesium (Mg), iron (Fe), etc.

[0030] The insulator 3 is composed of, for example, PFA (perfluoroalkoxy alkane), FEP (tetrafluoroethylene-hexafluoropropylene copolymer) fluorinated ethylene resin, polyethylene, polypropylene, etc. The insulator 3 can be a foamed resin or can be composed of a resin crosslinked to improve heat resistance. Moreover, the insulator 3 can also further form a multi-layer structure. For example, it can also form the following three-layer structure: a first non-foamed layer composed of non-foamed polyethylene is provided around the conductor 2, a foamed layer composed of foamed polyethylene is provided around the first non-foamed layer, and a second non-foamed layer composed of non-foamed polyethylene is provided around the foamed layer. In the present embodiment, around the conductor 2, the insulator 3 composed of PFA is formed by tube extrusion. By forming the insulator 3 by tube extrusion, it is easy to peel the insulator 3 from the conductor 2 during terminal processing, improving the terminal processability. Hereinafter, the conductor 2 and the insulator 3 are collectively referred to as the core part 6.

[0031] The shielding layer 4 is composed of a transverse winding shield formed by spirally winding a plurality of metal wires 41 around the insulator 3. In the coaxial cable 1 of the present embodiment, the shielding layer 4 is formed by burying a part of the circumferential direction of the plurality of metal wires 41 into the insulator 3. That is, in the present embodiment, on the surface of the part of the insulator 3 in contact with the plurality of metal wires 41, there are recesses 3a fitted with the plurality of metal wires 41, and the part of the shielding layer 4 in contact with the insulator 3 in the circumferential direction of the plurality of metal wires 41 is fitted with the recesses 3a of the insulator 3.

[0032] As Figure 1 shown in (b) of, the inner part of each metal wire 41 in the cable radial direction becomes a state of being embedded in the recess 3a of the insulator 3 and being in close contact with the insulator 3 (the inner circumferential surface of the recess 3a). Hereinafter, the part of the outer circumferential surface of the metal wire 41 that is fitted with the recess 3a of the insulator 3 and is in close contact with the insulator 3 is referred to as the fitting part 41a. On the outer circumferential surface of the insulator 3, there are unevenness corresponding to the shape of the metal wire 41, and concave recesses 3a for accommodating a part of the metal wire 41 (abutting against the fitting part 41a) and convex parts 3b located between the metal wires 41 adjacent in the circumferential direction are alternately formed in the circumferential direction.

[0033] Further, in the present embodiment, the shielding layer 4 is configured such that the metal wire rods 41 adjacent to each other in the circumferential direction are in surface contact with each other. At the portion where the metal wire rods 41 adjacent to each other in the circumferential direction are in contact, the metal wire rods 41 are deformed into a substantially flat shape and the metal wire rods 41 are in contact with each other without a gap. Hereinafter, the substantially flat portion where the metal wire rods 41 are in contact with each other is referred to as a wire rod contact portion 41b.

[0034] For example, if only a plurality of metal wire rods 41 are spirally wound around the insulator 3 to form a laterally wound shielding member, when the coaxial cable is bent, a gap is generated between the metal wire rods 41, resulting in a deterioration of the noise characteristics. Further, due to the influence of the gap generated between the metal wire rods 41, an absorption phenomenon in which a sharp attenuation occurs in a predetermined frequency band (for example, a frequency band such as 10 GHz) appears. As described in the present embodiment, in the shielding layer 4, a part of the metal wire rod 41 is buried in the recess 3a of the insulator 3, and the metal wire rods 41 adjacent to each other in the circumferential direction are in surface contact with each other. Thus, when the coaxial cable 1 is bent, each metal wire rod 41 deforms following the bending motion of the insulator 3, and thus it is difficult to generate a gap between the metal wire rods 41. Further, each metal wire rod 41 fitted into the recess 3a moves in the cable length direction along the recess 3a with respect to the bending of the insulator 3. Thereby, even in the case of bending wiring, the noise characteristics can be improved, and further, the generation of absorption can be suppressed in a frequency band up to 26 GHz.

[0035] Further, by burying the metal wire rod 41 in the insulator 3, when the sheath 5 is removed at the cable terminal portion during terminal processing to expose the shielding layer 4, the metal wire rod 41 is difficult to unwind, and thus the terminal processing can be easily performed. Further, since the metal wire rod 41 is in close contact with the insulator 3, the distance between the conductor 2 and the shielding layer 4 can be constantly maintained in the length direction, and the impedance can be stably and constantly maintained in the cable length direction.

[0036] When the coaxial cable 1 is bent, each metal wire rod 41 moves in the cable length direction along the recess 3a. In order to easily deform following the motion of the insulator 3, in a cross section perpendicular to the cable length direction, it is preferable to bury 1 / 6 or more of the outer peripheral length of a plurality of metal wire rods 41 in the insulator 3 (in close contact with the inner peripheral surface of the recess 3a of the insulator 3). That is, it is sufficient that the length L in the circumferential direction of the metal wire rod 41 of the fitting portion 41a is 1 / 6 or more of the outer peripheral length of the metal wire rod 41. Further, in other words, the range where the central angle of the outer peripheral surface of each metal wire rod 41 is 60 degrees or more is the fitting portion 41a. The length L of the portion in which the metal wire rod 41 is buried is obtained, for example, by observing a cross section of the coaxial cable 1 (a cross section perpendicular to the length direction of the coaxial cable 1) using an optical microscope or an electron microscope.

[0037] When heating is performed with the metal wire 41 wound around the core 6, the metal wire 41 is compressed in the radially inner side of the cable through a die to form the shielding layer 4, which will be described in detail below. At this time, friction is generated between the metal wire 41 and the inner peripheral surface of the die, so that on the part of each metal wire 41 on the radially outer side of the cable (the part facing the fitting portion 41a), an outer portion 41c composed of a substantially flat surface is formed. In addition, since the shape of the outer portion 41c is along the shape of the inner peripheral surface of the die, it may also be a slightly curved surface, rather than a completely flat surface.

[0038] In the present embodiment, the metal wire 41 is buried and fixed in the insulator 3 (that is, the metal wire 41 is fitted into the recess 3a, and a state where a part of the inner peripheral surface of the recess 3a is in close contact with the outer peripheral surface of the metal wire 41). Moreover, in order to maintain this state and ensure the bendability of the coaxial cable 1, it is preferable to use a wire made of a material that is easily plastically deformed and has a low yield strength as the metal wire 41. More specifically, as the metal wire 41, a metal wire having a tensile strength of 200 MPa or more and 380 Pa or less and an elongation rate of 7% or more and 20% or less can be used.

[0039] In the present embodiment, as the metal wire 41, a silver-plated soft copper wire having a plating layer 412 made of silver around a metal wire 411 made of soft copper wire is used. In addition, the metal wire 411 is not limited to a soft copper wire, and a copper alloy wire, an aluminum wire, an aluminum alloy wire, or a wire having a low softening temperature with a small amount of impurities added to pure copper can be used. Moreover, the metal constituting the plating layer 412 is not limited to silver, and for example, it can also be tin or gold, and the plating layer 412 can also be omitted.

[0040] Moreover, when the metal wire 41 is a soft copper wire, the conductivity of the metal wire 41 can be 98% IACS, and when the metal wire 41 is a copper alloy wire, the conductivity can be 80% IACS or more. In the present embodiment, improvement of the conductivity is achieved by performing heat treatment (second heating process) after the compression process. The details of the manufacturing method of the coaxial cable 1 will be described below.

[0041] The sheath 5 is made of, for example, a fluorinated ethylene resin such as PFA or FEP, polyvinyl chloride, crosslinked polyolefin, or the like. In order to improve the terminal processability, the sheath 5 is preferably formed into a tubular shape by tube extrusion or insert extrusion, and is preferably formed so as not to enter between the metal wires 41 of the shielding layer 4. In the present embodiment, the sheath 5 made of a fluorinated ethylene resin is formed by tube extrusion.

[0042] The sheath 5 is used to protect the core 6 and the shielding layer 4. However, in this embodiment, it also functions to fasten the metal wire 41 from the radially outer side to the inner side of the cable and hold the metal wire 41 in a state where it is pressed against the insulator 3. Therefore, the sheath 5 is preferably arranged to fasten the shielding layer 4 from the radially outer side to the inner side of the cable.

[0043] (Manufacturing method of coaxial cable 1)

[0044] Figure 2 is a flowchart in the manufacturing of the coaxial cable 1. As Figure 2 shown, when manufacturing the coaxial cable 1, first, in step S1, a core forming process is performed. In the core forming process, an insulator 3 is coated around the conductor 2 composed of a stranded conductor by extrusion molding to form the core 6. In order to easily peel the insulator 3 from the conductor 2 during terminal processing, it is preferable to form the insulator 3 by tube extrusion or insert extrusion.

[0045] After that, in step S2, a wire winding process is performed. In the wire winding process, a plurality of metal wires 41 are wound around the core 6 in a spiral shape. If the metal wires 41 are wound without gaps in the wire winding process, even if the metal wires 41 are pressed inward in the radial direction of the cable in the following compression process, it is difficult for the metal wires 41 to move inward in the radial direction of the cable, and there is a concern that the metal wires 41 cannot be buried in the insulator 3. Therefore, in the wire winding process, it is preferable to wind a plurality of metal wires 41 in such a way that a certain degree of gap can be formed between the metal wires 41. Specifically, in a cross-section perpendicular to the axial direction of the cable, the total value of the distances (the lengths of the gaps) between adjacent metal wires 41 in the circumferential direction is preferably 1 times or more and 1.5 times or less the outer diameter of the metal wire 41.

[0046] After that, in step S3, a first heating process is performed. In the first heating process, as Figure 3 shown, the core 6 wound with the metal wires 41 is heated by the heater 71. At this time, it is heated to a temperature above the softening temperature of the insulator 3 to soften the insulator 3. At this time, it is preferably heated to a temperature at which the insulator 3 will not melt.

[0047] After that, in step S4, a compression process is performed. In the compression process, as Figure 3 shown, the metal wires 41 and the core 6 heated in the first heating process are passed through the die 72, and the metal wires 41 are compressed toward the core 6 side (radially inward of the cable). The aperture of the die 72 is formed smaller than the outer diameter when the metal wires 41 are wound around the core 6, and by passing the core 6 and the metal wires 41 through the die 72, the metal wires 41 are compressed radially inward of the cable.

[0048] Due to the first heating process, the insulator 3 becomes in a softened state. Therefore, by performing the compression process, a part of the circumferential direction of the metal wire 41 is buried in the insulator 3. By burying the metal wire 41, a recess 3a is formed on the outer peripheral surface of the insulator 3, and a part of the metal wire 41 is fitted into the recess 3a. Moreover, by the flow of the material when forming the recess 3a, a bulge is generated at the position between the metal wires 41 adjacent in the circumferential direction, thereby forming a convex portion 3b. Since the convex portion 3b is formed to block the gap formed between the metal wires 41 adjacent in the circumferential direction and the insulator 3, it contributes to the improvement of the electrical characteristics when transmitting high-frequency signals.

[0049] Moreover, in the compression process, the metal wires 41 arranged in the circumferential direction are pressed inward in the radial direction of the cable, and the metal wires 41 adjacent in the circumferential direction are flattened against each other to be in a surface contact state, forming a wire contact portion 41b. Furthermore, at this time, by causing friction between the metal wire 41 and the inner peripheral surface of the die 72, an outer portion 41c composed of a substantially flat surface is formed on each metal wire 41.

[0050] After that, in step S5, a second heating process is performed. In the second heating process, as Figure 3 shown, the metal wire 41 is heated by the heater 73 to perform annealing of the metal wire 41. Thereby, the strain (residual strain) of the metal wire 41 caused by the compression process is alleviated. And by alleviating the strain (residual strain) of the metal wire 41, the force by which the metal wire 41 tends to return to a straight shape is alleviated. Since the shape wound around the core 6 is maintained, when the sheath 5 is removed, the metal wire 41 is difficult to unwind, which contributes to the improvement of the terminal workability. Through steps S2 to S5 like this, the shielding layer 4 is formed. In addition, when it is not necessary to alleviate the strain (stress strain) of the metal wire 41, step S5 can also be omitted.

[0051] After that, in step S6, a sheath forming process is performed. In the sheath forming process, the sheath 5 is covered around the shielding layer 4 by extrusion molding. In order to improve the terminal workability, the sheath 5 is preferably formed by tube extrusion or insert extrusion. Through the above processes, the coaxial cable 1 is obtained.

[0052] (Other manufacturing methods)

[0053] In the present embodiment, the metal wire 41 is buried in the insulator 3 in the compression process, but it is not limited thereto. The insulator 3 having the recess 3a can also be pre-formed by extrusion molding or the like. After that, a plurality of metal wires 41 are spirally wound in a manner fitted to the recess 3a, and then the lateral winding shield is compressed so that the plurality of metal wires 41 are in surface contact with each other, thereby forming the shielding layer 4. From the viewpoint of manufacturing ease, the manufacturing method preferably composed of the above steps S1 to S6 is preferred.

[0054] (Cable assembly)

[0055] Next, the cable assembly using the coaxial cable 1 will be described. Figure 4 It is a cross-sectional view showing the terminal portion of the cable assembly of the present embodiment.

[0056] As Figure 4 shown, the cable assembly 10 includes the coaxial cable 1 of the present embodiment and a terminal member 11 integrally provided at at least one end of the coaxial cable 1.

[0057] The terminal member 11 is, for example, a connector, a sensor, a substrate mounted in the connector or the sensor, or a substrate in an electronic device. Figure 4 The case where the terminal member 11 is the substrate 11a is shown. A signal electrode 12 to which the conductor 2 is to be connected and a ground electrode 13 to which the shielding layer 4 is to be connected are formed on the substrate 11a. The substrate 11a is composed of a printed circuit board, and a conductor pattern including the signal electrode 12 and the ground electrode 13 is printed on a base material 16 made of resin.

[0058] In the terminal portion of the coaxial cable 1, a part of the sheath 5 having a predetermined length is removed from the terminal to expose the shielding layer 4, and the terminal portions of the exposed shielding layer 4 and the insulator 3 are removed to expose the conductor 2. The exposed conductor 2 is fixed to the signal electrode 12 by a connecting material 14 such as solder, and the conductor 2 is electrically connected to the signal electrode 12. Further, the exposed shielding layer 4 is fixed to the ground electrode 13 by a connecting material 15 such as solder, and the shielding layer 4 is electrically connected to the ground electrode 13. In addition, the connection of the conductor 2 and the shielding layer 4 may not use the connecting materials 14 and 15 such as solder. For example, the conductor 2 and the shielding layer 4 may be connected by fixing the conductor 2 and the shielding layer 4 to a fixing metal part by riveting or the like. And, when the terminal member 11 is a connector or a sensor, the structure may be such that the conductor 2 and the shielding layer 4 are directly connected to the electrodes and elements.

[0059] (Functions and effects of the embodiment)

[0060] As described above, in the coaxial cable 1 of the present embodiment, the shielding layer 4 is composed of a laterally wound shield, and the surface of the portion of the insulator 3 in contact with the plurality of metal wires 41 has recesses 3a fitted to the plurality of metal wires 41. The portion of the shielding layer 4 in contact with the insulator 3 in the circumferential direction of the plurality of metal wires 41 is fitted to the recesses 3a of the insulator 3, and the plurality of metal wires 41 adjacent to each other in the circumferential direction of the shielding layer 4 are in surface contact with each other.

[0061] It is configured such that a part of the metal wire 41 is fitted into the recess 3a of the insulator 3, and the metal wires 41 adjacent to each other in the circumferential direction are in surface contact with each other. Thus, even when the coaxial cable 1 is repeatedly bent, it is difficult for gaps to be generated between the metal wires 41. By suppressing the gaps between the metal wires 41, the noise characteristics can be improved, and the generation of suction can be suppressed. That is, according to the present embodiment, it is possible to realize a coaxial cable 1 in which it is difficult for the shielding effect to be reduced and it is difficult for a sharp attenuation to occur in a predetermined frequency band.

[0062] For example, when the coaxial cable 1 is used as internal wiring of an electronic device, the coaxial cable 1 is mostly wired in a state bent in an S shape or an L shape. In the coaxial cable 1 of the present embodiment, since the metal wire 41 is buried in the insulator 3, the metal wire 41 deforms following the bending of the insulator 3. That is, in the present embodiment, even when the coaxial cable 1 is bent in an S shape or an L shape, the state where the metal wire 41 is buried in the insulator 3 is maintained, and the state where the metal wires 41 are in surface contact with each other is maintained. As a result, even when the coaxial cable 1 is bent and laid, it is difficult for gaps to be generated between the metal wires 41, and thus deterioration of the noise characteristics and electrical characteristics can be suppressed.

[0063] Moreover, by burying the metal wire 41 in the insulator 3, when the sheath 5 is removed, the metal wire 41 is difficult to come loose, the terminal processability can be improved, and the disorder of the shielding layer 4 at the cable terminal portion can be suppressed to improve the electrical characteristics. Further, the distance between the conductor 2 and the shielding layer 4 can be constantly maintained in the length direction, and the impedance can be stably and constantly maintained in the cable length direction.

[0064] (Other Embodiments)

[0065] Figure 5 It is a cross-sectional view showing a cross-section perpendicular to the length direction of a coaxial cable according to another embodiment of the present invention. Figure 5 The shown coaxial cable 1 and Figure 1 the coaxial cables 1 in (a) and (b) of

[0066] differ only in that they have a co-plating portion 42. The co-plating portion 42 is provided to cover the entire periphery of the laterally wound shield (laterally wound shield portion) together, and together with the laterally wound shield portion, constitutes the shielding layer 4 as an outer conductor. The co-plating portion 42 is composed of a conductive plating portion that connects adjacent metal wires 41 to each other. By providing the co-plating portion 42, the gaps between the metal wires 41 can be blocked by the co-plating portion 42, and thus the noise characteristics can be further improved. Moreover, since there are no gaps between the metal wires 41, the generation of suction can be further suppressed in the frequency band up to 26 GHz.

[0067] In this embodiment, as the co - plating part 42, a component made of tin is used. However, it is not limited thereto. As the co - plating part 42, for example, components made of silver, gold, copper, etc. can be used. Among them, from the viewpoint of ease of manufacturing, it can be said that it is more preferable to use the co - plating part 42 made of tin.

[0068] After forming a horizontally wound shield by spirally winding a plurality of metal wires 41 around the insulator 3, the horizontally wound shield is passed through a bath storing molten tin, thereby forming a co - plating part 42 composed of a molten plating part. At this time, in order for tin to easily adhere to the periphery of the horizontally wound shield, it is preferable to apply a flux to the periphery of the horizontally wound shield and then pass the horizontally wound shield through the bath storing molten tin. As the flux, for example, a rosin - based flux can be used.

[0069] Here, a silver - plated soft copper wire is used as the metal wire 41, and a plating layer 412 made of silver is provided on the surface of the metal wire 41. When forming the co - plating part 42, silver in the plating layer 412 forming the part in contact with the molten tin diffuses into the tin in the bath, thereby forming an intermetallic compound 413 containing copper and tin between the metal wire 41 and the co - plating part 42. The inventors et al. performed EDX analysis (analysis based on energy - dispersive X - ray spectroscopy) using SEM (scanning electron microscope) and were able to confirm the presence of the intermetallic compound 413 composed of copper and tin on the surface of the metal wire 41. In addition, it is considered that silver constituting the plating layer 412 is contained in the intermetallic compound 413, but the content of silver in the intermetallic compound 413 is an extremely small amount that is difficult to detect in EDX analysis.

[0070] On the metal wire 41 of the part not in contact with the co - plating part 42 (the metal wire 41 of the part not in contact with the molten tin during electroplating), the plating layer 412 made of silver still remains. That is, in the fitting part 41a, the wire contact part 41b, and the part between the fitting part 41a and the wire contact part 41b, the plating layer 412 made of silver remains. In the transmission of high - frequency signals, since the current concentrates on the insulator 3 side in the shield layer 4, by the presence of the plating layer 412 made of silver, a decrease in the conductivity of the shield layer 4 can be suppressed, and good attenuation characteristics can be maintained.

[0071] (Application in a multi - core cable)

[0072] Moreover, the present invention can also be applied to a multi - core cable. Figure 6 The multi - core cable 100 shown is Figure 1In the coaxial cable 1, the conductor 2 and the insulator 3 are replaced with a cable core 103. The cable core 103 has: a plurality of (here, four) insulated wires 101 having a conductor 101a and an insulator 101b covering the periphery of the conductor 101a; and an inner sheath 103 covering the periphery of the stranded insulated wires 101. On the surface of the part of the inner sheath 103 that contacts the plurality of metal wires 41, there are recesses 103a that fit with the plurality of metal wires 41. The portions of the plurality of metal wires 41 of the shielding layer 4 that contact the inner sheath 103 in the circumferential direction fit into the recesses 103a of the inner sheath 103, and the plurality of metal wires 41 adjacent to each other in the circumferential direction of the shielding layer 4 are in surface contact with each other. The inner sheath 103 can also be formed by tube extrusion, for example. Thus, compared with the case where the inner sheath 103 is formed by filling extrusion, it is easier to remove the inner sheath 103 during terminal processing to expose the insulated wires 101, thereby improving the workability of terminal processing. In addition, in the multi-core cable 100, the shielding layer 4 can also be the same as the Figure 5 coaxial cable 1 shown, and is structured with a plating portion that integrally covers the entire periphery of the horizontally wound shielding member composed of a plurality of metal wires 41.

[0073] In addition, a plurality of Figure 1 coaxial cables 1 can be bundled, and a sleeve can be provided to cover their periphery as a whole, thereby forming a multi-core cable. Furthermore, a Figure 1 coaxial cable 1 and other wires can be bundled, and a sheath can be provided to cover their periphery as a whole, thereby forming a multi-core cable.

[0074] (Summary of the Embodiment)

[0075] Next, the technical idea grasped from the above-described embodiment will be described by referring to the symbols in the embodiment. Among them, the symbols and the like in the following description do not limit the components in the claims to the components specifically shown in the embodiment.

[0076] [1] A coaxial cable 1, comprising: a conductor 2; an insulator 3 covering the periphery of the conductor 2; a shielding layer 4 composed of a horizontally wound shielding member that spirally winds a plurality of metal wires 41 to cover the periphery of the insulator 3; and a sheath 5 covering the periphery of the shielding layer 4. On the surface of the part of the insulator 3 that contacts the plurality of metal wires 41, there are recesses 3a that fit with the plurality of metal wires 41. The portions of the shielding layer 4 that contact the insulator 3 in the circumferential direction of the plurality of metal wires 41 fit into the recesses 3a of the insulator 3, and the plurality of metal wires 41 adjacent to each other in the circumferential direction of the shielding layer 4 are in surface contact with each other.

[0077] [2] For the coaxial cable 1 described in [1], in a cross-section perpendicular to the cable length direction, more than 1 / 6 of the outer circumference length of the plurality of metal wires 41 is fitted into the recess 3a of the insulator 3.

[0078] [3] For the coaxial cable 1 described in [1] or [2], the tensile strength of the plurality of metal wires 41 is 200 MPa or more and 380 Pa or less, and the elongation rate is 7% or more and 20% or less.

[0079] [4] A method for manufacturing a coaxial cable 1, the coaxial cable comprising: a conductor 2; an insulator 3 covering the periphery of the conductor 2; a shielding layer 4 composed of a laterally wound shield, the laterally wound shield being spirally wound with a plurality of metal wires 41 so as to cover the periphery of the insulator 3; and a sheath 5 covering the periphery of the shielding layer 4. The method for manufacturing the coaxial cable includes: a core forming step in which the insulator 3 is coated around the conductor 2 by extrusion molding to form a core 6; a wire winding step in which a plurality of metal wires 41 are spirally wound around the core 6; a first heating step in which the core 6 wound with the plurality of metal wires 41 is heated to soften the insulator 6; a compression step in which the heated plurality of metal wires and the core 6 are passed through a die 72, and the metal wires 41 are compressed toward the core 6 side, whereby the insulator 3 forms a recess 3a fitted with the plurality of metal wires 41 on the surface of the portion in contact with the plurality of metal wires 41, and the portions of the plurality of metal wires 41 in contact with the insulator 3 in the circumferential direction are fitted into the recess 3a of the insulator 3, and the plurality of metal wires 41 adjacent to each other in the circumferential direction of the shielding layer 4 are in surface contact with each other to form the shielding layer 4; a second heating step in which the shielding layer 4 is heated to relieve the strain of the metal wires 41 caused by the compression step; and a sheath forming step in which the sheath 5 is coated around the shielding layer 4 by extrusion molding.

[0080] [5] A cable assembly 10, comprising: the coaxial cable 1 described in any one of [1] to [3]; and a terminal member 11 integrally provided at at least one end of the coaxial cable 1.

[0081] Above, the embodiments of the present invention have been described, but the embodiments described above do not limit the invention of the claims. And it should be noted that the combination of all features described in the embodiments is not limited to being necessary for the solution to solve the problems of the invention. Furthermore, the present invention can be appropriately modified and implemented without departing from its gist.

Claims

1. A coaxial cable, characterized in that, Comprising: A conductor; An insulator covering the periphery of the above conductor; A shielding layer having a laterally wound shield, the laterally wound shield being spirally wound with a plurality of metal wires so as to cover the periphery of the above insulator; And A sheath covering the periphery of the above shielding layer, The above insulator has recesses engaging with the respective metal wires of the above plurality of metal wires on the surface of the portion in contact with each metal wire of the above plurality of metal wires, The portion of the above shielding layer in contact with the above insulator in the circumferential direction of the above plurality of metal wires engages with the above recesses of the above insulator, and the above plurality of metal wires adjacent to each other in the circumferential direction of the above shielding layer are in surface contact with each other, Each metal wire fitted into the above recess moves in the cable length direction along the above recess in a manner following the bending of the above insulator with respect to the above insulator.

2. The coaxial cable according to claim 1, characterized in that In a cross section perpendicular to the cable length direction, 1 / 6 or more of the outer peripheral length of the above plurality of metal wires engages with the above recesses of the above insulator.

3. The coaxial cable according to claim 1 or 2, characterized in that The elongation rate of the above plurality of metal wires is 7% or more and 20% or less.

4. A method for manufacturing a coaxial cable, the coaxial cable comprising: A conductor; An insulator covering the periphery of the above conductor; A shielding layer formed of a laterally wound shield, the laterally wound shield being spirally wound with a plurality of metal wires so as to cover the periphery of the above insulator; and A sheath covering the periphery of the above shielding layer, The method for manufacturing the above coaxial cable is characterized by comprising: A core forming step in which the above insulator is coated around the above conductor by extrusion molding to form a core; A wire winding step in which a plurality of metal wires are spirally wound around the above core in such a manner as to form a certain degree of gap between the above metal wires; A first heating step in which the above core wound with the above plurality of metal wires is heated to soften the above insulator; A compression step in which the heated above plurality of metal wires and the above core are passed through a die, and the above metal wires are compressed toward the above core side, whereby recesses engaging with the respective metal wires of the above plurality of metal wires are formed on the surface of the portion of the above insulator in contact with the plurality of metal wires, and the portion of the plurality of metal wires in contact with the above insulator in the circumferential direction engages with the above recesses of the above insulator, and the above plurality of metal wires adjacent to each other in the circumferential direction of the above shielding layer are in surface contact with each other, thereby forming the above shielding layer; A second heating step in which the above shielding layer is heated to relieve the strain of the above metal wires caused by the above compression step; and A sheath forming step in which the above sheath is coated around the above shielding layer by extrusion molding.

5. A cable assembly, characterized in that, Comprising: The coaxial cable according to any one of claims 1 to 3; and Terminal components integrally provided at at least one end of the above coaxial cable.

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