Coaxial cable

Abstract

[Problem] To provide a coaxial cable that has a good appearance and has excellent workability. [Solution] The foregoing problem was solved by providing a cable constituted of: a central conductive body 11; an insulative body 12 provided along the circumference of the central conductive body 11; an external conductive body (13, 14) provided along the circumference of the insulative body 12; and a coating body (15, 16) that coats the external conductive body (13, 14). The external conductive body (13, 14) is constituted of: a crosswise-wound shield 13, which is provided by laying fine metal wires one next to the other around the circumference of the conductive body 12; and a metal resin tape 14, which wraps around the crosswise-wound shield 13 in layers, with a metal layer side inward. The coating body (15, 16) is constituted of: a resin tape 15 which wraps around the metal resin tape 14; and an extruded sheath 16 that covers the resin tape 15. When the thickness of the metal resin tape 14 is T1 and the thickness of the resin tape 15 is T2, T2 / T1 is in a range of 0.180-0.800.

Description

Technical Field

[0001] The present invention relates to a coaxial cable. More specifically, the present invention relates to a coaxial cable used for in-device antenna wiring and semiconductor devices corresponding to the fifth-generation communication standard (5G), having a good appearance and excellent workability.

Background Art

[0002] Since coaxial cables have excellent shielding characteristics against noise and the like, they are used for transmitting high-frequency signals. Such coaxial cables have a problem that when an external force acts on the cable, the insulator deforms, the impedance fluctuates, reflection attenuation occurs, and the transmission efficiency decreases. In addition, coaxial cables used for in-device antenna wiring and semiconductor devices are required to have a smaller diameter and good bending characteristics.

[0003] In response to such requirements, Patent Document 1 proposes a coaxial cable that satisfies shielding characteristics, flexibility, a smaller diameter configuration, bending resistance, and economy, and improves terminal workability. This coaxial cable has a structure in which a center conductor, an insulator, an outer conductor having a horizontally wound shield structure, and an outer sheath are coaxially laminated in sequence. When the outer sheath is PFA, the insulator is formed of fluorinated PFA, and when the outer sheath is FEP or FTFE, the insulator is formed of any of fluorinated FEP, PFA, and fluorinated PFA. Further, it is proposed that a tape layer on which metal is vapor-deposited or plated is provided between the insulator and the outer conductor, the horizontal winding angle of the horizontal winding wire of the outer conductor is set to 70 to 85°, and the center conductor is a multi-strand or single-strand conductor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] In recent years, coaxial cables have been used to transmit high-frequency signals within electronic devices such as personal computers, smartphones, and tablet devices, which are becoming increasingly smaller, and there is a demand for even thinner cables to enable wiring within devices in tight spaces.In particular, coaxial cables used for antenna wiring within devices compatible with the fifth-generation communication standard (5G) and semiconductor devices require small diameters and good transmission characteristics.

[0006] The coaxial cable of Patent Document 1 has an outer conductor made of a horizontally wound shield, which is made of thin wires wound horizontally. This is advantageous for reducing the diameter compared to conventional outer conductors made of braided shields made of thin wires. However, horizontally wound shields tend to cause gaps between the horizontally wound thin wires during wiring, which can reduce the shielding effectiveness. To solve this problem, a metal-resin tape is wrapped around the horizontally wound shield with a specified amount of overlap to prevent the reduction in shielding effectiveness.

[0007] When metal-resin tape is wound over and over, air remains in the gaps created by the thickness of the metal-resin tape. This air expands due to the heat generated when the extrusion sheath is subsequently extruded, creating unevenness and a poor appearance. Therefore, extrusion molding is performed while using a vacuum pump to remove as much air as possible, but this has not been fully resolved. These uneven appearances change the outer diameter of the coaxial cable in the longitudinal direction, and if the same terminal processing conditions are used when connecting the terminal to a connector, the processing yield deteriorates, so the terminal processing conditions sometimes had to be changed each time.

[0008] The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a coaxial cable that has a good appearance and is easy to process, and that can be used for internal antenna wiring in devices and semiconductor devices that are compatible with the fifth-generation communication standard (5G). [Means for solving the problem]

[0009] The coaxial cable of the present invention is a coaxial cable comprising a central conductor, an insulator arranged around the central conductor, an outer conductor arranged around the insulator, and an outer jacket covering the outer conductor, wherein the outer conductor is composed of a horizontally wound shield formed by horizontally winding thin metal wires around the insulator, and a metal-resin tape wound around the horizontally wound shield with the metal layer side facing inward, and the outer jacket is composed of a resin tape wound around the metal-resin tape and an extruded sheath covering the resin tape, and wherein, when the thickness of the metal-resin tape is T1 and the thickness of the resin tape is T2, T2 / T1 is in the range of 0.180 or more and 0.800 or less.

[0010] According to this invention, since the thickness T2 of the resin tape and the thickness T1 of the metal-resin tape satisfy the above-mentioned relationship, the step difference can be reduced (approximately 0.180 to 0.800) compared to when only the metal-resin tape is used, and the appearance irregularities caused by the air present in the step can be suppressed. As a result, the change in the outer diameter in the longitudinal direction can be suppressed, allowing the terminal to be processed under the same conditions when connecting to a connector. Furthermore, since the outer conductor has a horizontally wound shield, it can be made thinner than a braided shield. Furthermore, since the metal-resin tape is provided on the horizontally wound shield, even if a gap occurs in the horizontally wound shield, the reduction in shielding effectiveness can be suppressed. Such a coaxial cable can be made thinner to enable wiring within a device in a narrow space, and is particularly suitable for use in antenna wiring within devices compatible with the fifth-generation communication standard (5G) and semiconductor devices.

[0011] In the coaxial cable according to the present invention, the metal-resin tape is configured with one or two sheets. When configured with two sheets, the first metal-resin tape and the second metal-resin tape are wound in an overlapping manner, but by winding one metal-resin tape first, the rigidity of the coaxial cable can be increased. Furthermore, the role of the two metal-resin tapes as a whole is to increase the amount of metal, thereby further improving the shielding effect of the coaxial cable.

[0012] In the coaxial cable according to the present invention, when the metal-resin tape is composed of two metal-resin tapes, the thickness of the first metal-resin tape is the same as that of the second metal-resin tape, or the thickness of the first metal-resin tape is thinner than that of the second metal-resin tape. According to this invention, by making the first and second metal-resin tapes have the above thicknesses, the strain applied to the coaxial cable when winding the metal-resin tape can be reduced. In particular, by increasing the total thickness, the shielding characteristics at higher frequencies can be improved. Furthermore, winding the thin first metal-resin tape first increases the rigidity of the coaxial cable, making it easier to wind the thick second metal-resin tape thereafter.

[0013] In the coaxial cable according to the present invention, when the metal-resin tape is composed of a single metal-resin tape, the thickness of the metal-resin tape is 8 μm or more and 18 μm or less, and the thickness of the resin tape is 4 μm or more and 9 μm or less. According to this invention, since the thickness of the metal-resin tape and the thickness of the resin tape are within the above ranges, the step can be made smaller (approximately 9 μm or less) compared to when only a metal-resin tape is used.

[0014] In the coaxial cable according to the present invention, when the metal-resin tape is composed of two metal-resin tapes, the total thickness of the two metal-resin tapes is 16 μm or more and 26 μm or less, and the thickness of the resin tape is 4 μm or more and 9 μm or less. According to this invention, since the thickness of the metal-resin tape and the thickness of the resin tape are within the above ranges, the step can be made smaller (approximately 9 μm or less) compared to when only a metal-resin tape is used. Furthermore, since the total thickness of the two metal-resin tapes is within the above range, the flexibility of the coaxial cable can be increased even when the two metal-resin tapes are overlap-wound.

[0015] In the coaxial cable according to the present invention, the metal resin tape and the resin tape are wound around each other in a range from 1 / 4 lap to 1 / 2 lap. According to this invention, the step when wound around each other in these ranges can be reduced.

[0016] In the coaxial cable according to the present invention, an adhesive layer is provided on one surface of the resin tape, and it is wound so that the adhesive layer is on the inside. According to this invention, the metal resin tape is fixed by the adhesive layer of the resin tape so as not to shift, so even when stress is applied during wiring of the coaxial cable, no shift occurs in the transverse wound shield. As a result, a decrease in the shielding effect can be suppressed.

Effects of the Invention

[0017] According to the present invention, it is possible to provide a coaxial cable that is used for in-device antenna wiring and semiconductor devices corresponding to the fifth-generation communication standard (5G), has a good appearance, and is excellent in workability. In particular, since external appearance irregularities are suppressed, a change in the outer diameter in the longitudinal direction can be suppressed, and terminals can be processed under the same conditions when connecting the terminals to the connectors. In addition, a reduction in diameter can be achieved compared to a braided shield, and even when a gap occurs in the transverse wound shield, a decrease in the shielding effect can be suppressed.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0019] The following describes embodiments of a coaxial cable according to the present invention with reference to the drawings. The present invention includes inventions based on the same technical ideas as the embodiments described below and the embodiments shown in the drawings, and the technical scope of the present invention is not limited to the descriptions of the embodiments and the descriptions in the drawings.

[0020] [Coaxial cable] 1, a coaxial cable 10 according to the present invention is a coaxial cable including a central conductor 11, an insulator 12 disposed around the central conductor 11, outer conductors (13, 14) disposed around the insulator 12, and jackets (15, 16) covering the outer conductors (13, 14). The outer conductors (13, 14) are comprised of a horizontally wound shield 13 formed by horizontally winding thin metal wires around the outer periphery of the insulator 12, and a metal-resin tape 14 wound around the horizontally wound shield 13 with the metal layer facing inward. The jackets (15, 16) are comprised of a resin tape 15 wound around the metal-resin tape 14 and an extruded sheath 16 covering the resin tape 15. When the thickness of the metal-resin tape 14 is T1 and the thickness of the resin tape 15 is T2, the ratio T2 / T1 is within a range of 0.180 to 0.800.

[0021] This coaxial cable 10 has the following characteristics: (1) Since the thickness T1 of the metal resin tape 14 and the thickness T2 of the resin tape 15 satisfy the relationship of "0.180 ≤ T2 / T1 ≤ 0.800", the step can be made smaller (about 0.180 to 0.800) compared to the case of only the metal resin tape 14, and the appearance unevenness caused by the air existing in the step can be suppressed. As a result, the change in the outer diameter in the longitudinal direction can be suppressed, and the terminal can be processed under the same conditions when connecting the terminal to the connector. (2) Further, since the outer conductor has the spiral shield 13, a smaller diameter can be achieved compared to the braided shield. (3) Further, since the metal resin tape 14 is provided on the spiral shield 13, even if a gap occurs in the spiral shield 13, a decrease in the shielding effect can be suppressed. Such a coaxial cable 10 can achieve a smaller diameter for in-device wiring in a narrow space, and is particularly preferable for in-device antenna wiring corresponding to the fifth-generation communication standard (5G) or for semiconductor devices.

[0022] Hereinafter, each component will be described in detail.

[0023] As shown in FIG. 1, the coaxial cable 10 is composed of a center conductor 11, an insulator 12 provided on the outer periphery of the center conductor 11, an outer conductor (13, 14) provided on the outer periphery of the insulator 12, and an outer covering (15, 16) covering the outer conductor (13, 14).

[0024] (Center Conductor) The center conductor 11 is composed of a single strand extending in the longitudinal direction of the coaxial cable 10 or a plurality of strands twisted together. The type of the strand is not particularly limited as long as it is a good conductive metal, and examples thereof preferably include good conductive metal conductors such as copper wire, copper alloy wire, aluminum wire, aluminum alloy wire, and copper-aluminum composite wire, or those with a plating layer on their surfaces. From the viewpoint of high frequency use, copper wire and copper alloy wire are particularly preferable. As the plating layer, a solder plating layer, a tin plating layer, a gold plating layer, a silver plating layer, a nickel plating layer, etc. are preferable. The cross-sectional shape of the strand is not particularly limited, and it may be a wire having a circular or substantially circular cross-sectional shape, or a rectangular shape.

[0025] The cross-sectional shape of the center conductor 11 is not particularly limited either. It may be circular (including elliptical), rectangular, or the like, but circular is preferred. The outer diameter of the center conductor 11 is desirably as large as possible so that the electrical resistance (AC resistance, conductor resistance) is small. However, in order to reduce the final outer diameter of the coaxial cable 10, for example, it can be in the range of about 0.09 to 1 mm. An insulating film (not shown) may be provided on the surface of the center conductor 11 as necessary. The type and thickness of the insulating film are not particularly limited, but for example, those that decompose well during soldering are preferred, and thermosetting polyurethane films and the like can be preferably mentioned.

[0026] (Insulator) As shown in FIGS. 1 and 2, the insulator 12 is a low dielectric constant insulating layer continuously provided in the longitudinal direction on the outer periphery of the center conductor 11. The material of the insulator 12 is not particularly limited and is arbitrarily selected according to the required impedance characteristics. For example, fluorine-based resins with a low dielectric constant of 2.0 to 2.5 such as PFA (ε2.1), ETFE (ε2.5), FEP (ε2.1), etc. are preferred, and among them, PFA resin is preferred. Note that a coloring agent may be contained in the material of the insulator 12. The thickness of the insulator 12 is not particularly limited either and is arbitrarily selected according to the required impedance characteristics, but for example, it is preferably in the range of about 0.15 to 1.5 mm. The forming method of the insulator 12 is not particularly limited, but any of a solid structure, a hollow structure, and a foamed structure can be easily formed by extrusion.

[0027] The insulator 12 may have a solid structure as shown in FIG. 2(A), a hollow structure as shown in FIG. 2(B), or a foamed structure (not shown). The hollow structure has a void portion 12' inside the structure body, and for example, the cross-sectional form of surrounding the void portion 12' with an inner annular portion 12a, an outer annular portion 12b, and a connecting portion 12c can be adopted. When a hollow structure or a foamed structure is adopted, there is an additional effect that the material density of the insulator 12 is reduced and the flexibility of the insulator 12 is enhanced.

[0028] (Outer conductor) As shown in FIG. 1 , the outer conductors (13, 14) are disposed on the outer periphery of the insulator 12. The outer conductors (13, 14) are composed of a horizontally wound shield 13, which is formed by horizontally winding thin metal wires around the outer periphery of the insulator 12, and a metal-resin tape 14, which is wound over the horizontally wound shield 13 with the metal layer facing inward. The outer conductor, which has a double structure of the horizontally wound shield 13 and the metal-resin tape 14, has a large conductor cross-sectional area and can reduce insertion loss. Furthermore, since the outer conductor has the horizontally wound shield 13, it can be made thinner than a braided shield. Furthermore, since the metal-resin tape 14 is disposed on the horizontally wound shield 13 in a manner that electrically connects the thin wires (i.e., the thin wires and the metal layer are in direct contact), a decrease in shielding effectiveness can be suppressed even if stress is applied to the horizontally wound shield 13 and gaps occur between the thin wires.

[0029] (Horizontal winding shield) As shown in Fig. 1, the spirally wound shield 13 is formed by spirally winding thin metal wires on the insulator 12. The spirally wound thin metal wires may be a single layer as shown in Fig. 1 or a multilayer structure not shown, and are not particularly limited, but a single layer is preferable. Compared to a braided structure in which thin wires are crossed to form twists, the spirally wound shield 13 can be thinner while still providing the same degree of effect (sealing effect, etc.), which is advantageous from the perspective of reducing the diameter of the coaxial cable 10.

[0030] The fine metal wires are not particularly limited as long as they are fine metal wires with good conductivity that can be provided around the insulator 12 as the spirally wound shield 13 constituting the coaxial cable 10. For example, various fine metal wires, such as tin-plated copper wire, can be preferably used. The outer diameter of the fine metal wires is not particularly limited and is determined in relation to the outer diameter of the insulator 12, but can be, for example, in the range of about 0.04 to 0.1 mm. The number of fine metal wires is also selected arbitrarily depending on the outer diameter of the insulator 12, the intended outer diameter of the coaxial cable 10, etc. The spiral winding pitch when the fine metal wires are spirally wound is also not particularly limited, but is usually preferably about 0.5 to 11 mm.

[0031] (Metal Resin Tape) As shown in Fig. 1, the metal resin tape 14 is provided by winding horizontally (spirally) on the horizontally wound shield 13. The metal resin tape 14 is at least composed of a resin base material and a metal layer provided on the outermost surface of one surface of the resin base material. This metal resin tape 14 is provided by winding horizontally with the side of the metal layer facing the side of the horizontally wound shield 13. By doing so, even if a gap occurs temporarily in the horizontally wound shield 13, since the fine wire of the horizontally wound shield 13 and the metal layer of the metal resin tape 14 are in direct contact, a decrease in the shielding effect can be suppressed. Note that the use of "at least" and "outermost surface" means that other layers may be optionally provided between the resin base material and the metal layer or on the other surface of the resin base material.

[0032] The metal resin tape 14 is wound in a range from 1 / 4 lap to 1 / 2 lap. By setting the lap within this range, contact between the metal layer constituting the metal resin tape 14 and the horizontally wound shield 13 can be ensured, and a stable shielding effect can be realized. If the lap is less than 1 / 4, the overlap is small, so there is a risk that the overlap will shift during horizontal winding. If the lap exceeds 1 / 2, the overlap of the metal resin tape 14 becomes large, which may be disadvantageous in terms of reducing the diameter. Note that the winding pitch of the metal resin tape 14 is not particularly limited because it can be arbitrarily set according to the width and lap of the metal resin tape 14. However, when the width of the metal resin tape 14 is within a range of, for example, about 3 to 6 mm, the winding pitch is preferably within a range of, for example, 1.5 to 10 mm. The horizontal winding direction of the metal resin tape 14 may be the same as or opposite to the horizontal winding direction of the above-described metal fine wire, but the opposite winding direction is preferred.

[0033] The horizontal winding of the metal resin tape 14 is wound in a state where the metal layer side faces the metal fine wires so that the metal layer is in direct contact with the metal fine wires of the horizontal winding shield 13. As a result, the metal fine wires and the metal layer of the metal resin tape can be brought into direct contact to make the electrical conduction more stable, and stable shielding characteristics can be ensured. By winding horizontally under the above-mentioned wrap, the metal layer can be directly and contact-arranged on the metal fine wires without creating a gap between the metal layers of the metal resin tape 14. Furthermore, since the horizontal winding state of the metal resin tape 14 itself is fixed by the adhesive layer of the resin tape 15, even if the metal fine wires shift slightly due to the stress during the wiring of the coaxial cable 10, the metal resin tape 14 provided thereon does not shift, so stable shielding characteristics can be ensured.

[0034] The resin base material constituting the metal resin tape 14 is not particularly limited, but polyester films such as polyethylene terephthalate and polyethylene naphthalate can be preferably used. The thickness of the resin base material is arbitrarily selected from those in the range of, for example, about 2 to 16 μm.

[0035] Examples of the metal layer constituting the metal resin tape 14 preferably include a copper layer and an aluminum layer. The metal layer is preferably a film formed by vapor deposition or plating on the resin base material, or a metal foil bonded through an adhesive layer (for example, a polyester-based thermoplastic adhesive resin, etc.) provided as necessary. The thickness of the metal layer is not particularly limited and varies depending on the forming means, but for those formed by vapor deposition or plating, it can be arbitrarily selected from the range of about 2 to 8 μm.

[0036] The thickness of the metal resin tape 14 is preferably in the range of about 8 to 18 μm. By setting it within this range, it can contribute to the reduction in the diameter of the coaxial cable 10.

[0037] As described above, the case where the metal resin tape 14 is composed of a single sheet as shown in FIG. 1 has been explained. However, the metal resin tape 14 may be composed of two metal resin tapes 14a and 14b as shown in FIG. 3. When the metal resin tape 14 is composed of two sheets, the first metal resin tape 14a and the second metal resin tape 14b are wound around each other. By winding the first metal resin tape first, the rigidity of the coaxial cable is increased. Then, when winding the second metal resin tape, it can be made easier to wind. Also, by increasing the amount of metal in the entire two metal resin tapes, the shielding effect of the coaxial cable can be enhanced.

[0038] Regarding the thickness, it is preferable that the thickness of the first metal resin tape is the same as the thickness of the second metal resin tape. By making the thickness the same, the metal resin tape can be wound under the same conditions, which has the advantage that the metal resin tape is easier to wind and the flexibility of the coaxial cable can be enhanced. On the other hand, the thickness of the first metal resin tape 14a can also be made thinner than the thickness of the second metal resin tape 14b. By doing so, the rigidity of the coaxial cable 10 can be increased with the first metal resin tape 14a, and when winding the second metal resin tape 14b, the distortion applied to the coaxial cable 10 can be reduced.

[0039] By increasing the total thickness of the two metal resin tapes 14a and 14b, the shielding characteristics at higher frequencies can be improved. Such a total thickness is preferably 16 μm or more and 26 μm or less, and specifically, the shielding characteristics can be -50 dB or less.

[0040] When the metal-resin tape 14 is composed of two metal-resin tapes 14a and 14b, the second metal-resin tape 14b is wound laterally (spiral wound) on the first metal-resin tape 14a, just as when the metal-resin tape 14 is composed of a single metal-resin tape. Similarly to the above, each metal-resin tape 14a and 14b is structured at least with a resin base material and a metal layer formed on the outermost surface of one side of the resin base material. The second metal-resin tape 14b is also wound laterally with the metal layer facing the first metal-resin tape 14a. By making the thickness of the two metal-resin tapes 14a and 14b thicker than the thickness of a single metal-resin tape 14, the rigidity of the coaxial cable 10 can be increased, and the strain on the coaxial cable 10 when the second metal-resin tape 14b is wound can be reduced. The first metal-resin tape 14a and the second metal-resin tape 14b are overlap-wound with a 1 / 4 to 1 / 2 wrap. By wrapping the two metal-resin tapes 14a and 14b within this range, contact between the metal layer constituting the metal-resin tape 14 and the horizontally wound shield 13 can be ensured, resulting in a stable shielding effect. The winding pitch of each metal-resin tape 14a and 14b is not particularly limited and can be set arbitrarily depending on the width and wrap of each metal-resin tape 14a and 14b.

[0041] When the two metal resin tapes 14a and 14b are wound horizontally, the metal layer of the first metal resin tape 14a is in direct contact with the metal fine wires of the horizontal winding shield 13, but the metal layer of the second metal resin tape 14b is not in direct contact with the metal layer of the first metal resin tape 14a. Even in this case, there is an advantage that the total amount of metal of the entire coaxial cable can be increased. Note that it is more preferable that the winding directions of the first metal resin tape 14a and the second metal resin tape 14b are opposite to each other, which can maintain the flexibility of the coaxial cable and also make it less likely for the metal resin tape to shift. Further, since the horizontal winding state of the second metal resin tape 14b itself is fixed by the adhesive layer of the resin tape 15, even if the metal fine wires shift slightly due to the stress during the wiring of the coaxial cable 10, the metal resin tape 14 provided thereon does not shift. However, the first metal resin tape 14a is not fixed by the adhesive layer of the resin tape 15. Even in this case, however, the first metal resin tape 14a has the advantage of being fixed by the tape winding tension of the second metal resin tape 14b.

[0042] The resin base materials and their thicknesses, and the metal layers and their thicknesses that constitute each of the two metal resin tapes 14a and 14b are the same as those described above. Also, the thickness of each of the metal resin tapes 14a and 14b is preferably in the range of about 8 to 18 μm as described above. However, the total thickness of the two metal resin tapes 14a and 14b is preferably in the range of 16 to 26 μm. By doing so, the step can be made smaller (about 9 μm or less) compared to the case where only the metal resin tape is used. Further, since the total thickness of the two metal resin tapes is within the above range, the impact generated when winding the two metal resin tapes 14a and 14b can be absorbed by the elasticity of the resin tape 15.

[0043] (Outer covering) The outer coverings (15, 16) are, as shown in FIG. 1, ExternalIt is provided on the outer periphery of the conductors (13, 14), more specifically, on the metal-resin tape 14. The outer coverings (15, 16) are composed of a resin tape 15 wound on the metal-resin tape 14, and an extruded sheath 16 that covers the resin tape 15. The materials of the resin tape 15 and the extruded sheath 16 are not particularly limited as long as they are insulating. The resin tape 15 is a resin tape having an adhesive layer on one side, and is provided by being spirally wound on the metal-resin tape 14. The extruded sheath 16 is an insulating sheath provided by extruding resin.

[0044] (resin tape) As shown in FIG. 1 , the resin tape 15 is wound laterally (spiral wound) on the metal-resin tape 14. The resin tape 15 is composed of at least a resin substrate and an adhesive layer provided on the outermost surface of one side of the resin substrate. The resin tape 15 is wound laterally with the adhesive layer facing the metal-resin tape 14. This adhesive fixes the resin tape 15 and the metal-resin tape 14, preventing the metal-resin tape 14 from shifting even when stress is applied during wiring. As a result, a decrease in the shielding effect of the metal-resin tape 14 and the horizontally wound shield 13 can be suppressed. Note that the terms "at least" and "outermost surface" mean that other layers may be optionally provided between the resin substrate and the adhesive layer or on the other side of the resin substrate. Furthermore, the other side does not have an adhesive layer and is not bonded to the extruded sheath 16 formed thereon. This has the advantage that, for example, when stress is applied during wiring, slippage occurs at the interface between the resin tape 15 and the extruded sheath 16, making the cable more flexible.

[0045] The resin tape 15 is wound around in the range from 1 / 4 lap to 1 / 2 lap, similar to the above-mentioned metal resin tape 14. By setting the lap within this range, the adhesive layer constituting the resin tape 15 can fix the resin tape 15 itself and adhere to the metal resin tape 14 to fix the metal resin tape 14. If the lap is less than 1 / 4, the overlap is small, so there is a risk that the overlap may shift during lateral winding. If the lap exceeds 1 / 2, the overlapping thickness of the resin tape 15 becomes thick, which may be disadvantageous in terms of reducing the diameter. The winding pitch of the resin tape 15 can be arbitrarily set according to the width and lap of the resin tape 15. However, when the width of the resin tape 15 is within a range of about 3 to 6 mm, for example, the winding pitch is preferably within a range of 1.5 to 10 mm. The lateral winding direction of the resin tape 15 may be the same as or opposite to the lateral winding direction of the above-mentioned metal resin tape 14, but the opposite direction is preferred.

[0046] In the coaxial cable 10 according to the present invention, when the thickness of the metal resin tape 14 is T1 and the thickness of the resin tape 15 is T2, T2 / T1 is within the range of 0.180 or more and 0.800 or less. By doing so, the step can be made smaller (about 7 μm or less) compared to the case where only the metal resin tape 14 is used. Therefore, it is possible to suppress the appearance irregularities caused by the air present in the step. As a result, the change in the outer diameter in the longitudinal direction can be suppressed, and the terminal can be processed under the same conditions when connecting the terminal to the connector.

[0047] When T2 / T1 is larger than 〇.8〇〇, a step will occur even in the resin tape 15, so a sufficient improvement effect may not be obtained. When T2 / T1 is smaller than 〇.18〇, the resin tape 15If it is too thin, the degree of the step of the metal resin tape 14 may remain as it is, and a sufficient improvement effect may not be obtained. The size of the step that affects the appearance varies depending on the overall outer diameter. For example, when a step of 10 μm or more occurs, the unevenness of the appearance becomes prominent, so it is preferable that the step is less than 10 μm. In addition, the thickness T2 of the resin tape 15 satisfies the relationship of "0.180 or more and 0.800 or less of T2 / T1", and specifically, it is preferably a thickness of 4 μm or more and less than 10 μm, more specifically 4 μm or more and 9 μm or less.

[0048] The resin base material constituting the resin tape 15 is not particularly limited. For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide (PA), polyimide (PI), polyphenylene sulfide (PPS), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), fluorinated resin copolymer (perfluoroalkoxy fluororesin: PFA), polyetheretherketone (PEEK), etc. can be mentioned. In particular, polyester films such as polyethylene terephthalate and polyethylene naphthalate can be preferably used. The thickness of the resin base material is arbitrarily selected from those in the range of about 2 to 6 μm, for example.

[0049] The adhesive layer constituting the resin tape 15 is provided on one side of the resin base material, and examples of its material include urethane-based adhesives, epoxy-based adhesives, acrylic-based adhesives, etc. The thickness of the adhesive layer is not particularly limited either, but it can be about 1 to 3 μm.

[0050] (Extrusion sheath) The extruded sheath 16 is provided on the resin tape 15 by extrusion molding. Various resins that are used in resin extrusion for jackets can be used as the constituent resin of the extruded sheath 16. For example, it may be a fluororesin such as PFA, ETFE, or FEP, a vinyl chloride resin, a polyolefin resin such as polyethylene, or a polyester resin such as polyethylene terephthalate. In the coaxial cable 10 according to the present invention, a fluororesin is preferred.

[0051] When providing the extrusion sheath 16, it is preferable to perform extrusion molding while suctioning with a vacuum pump so as to leave as little air as possible between the extrusion sheath 16 and the resin tape 15. The total thickness of the outer jacket formed by the extrusion sheath 16 and the resin tape 15 can be set within the range of about 0.1 to 1.0 mm, for example.

[0052] The final outer diameter of the obtained coaxial cable 10 is preferably within a range of approximately 0.6 to 3.5 mm. Such a coaxial cable 10 has reduced external irregularities and thus minimizes changes in outer diameter in the longitudinal direction, allowing the terminals to be processed under the same conditions when connected to a connector. Furthermore, it can achieve a smaller diameter than a braided shield, and even if gaps occur in a horizontally wound shield, it can suppress a decrease in shielding effectiveness. As a result, it can achieve a small diameter that allows wiring within a device in a narrow space, and is particularly suitable for use in antenna wiring within devices compatible with the fifth-generation communication standard (5G) and semiconductor devices. [Example]

[0053] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0054] [Example 1] First, a coaxial cable 10 in the form shown in FIG. 1 was fabricated. As the center conductor 11, a silver-plated soft copper wire with an outer diameter of 0.203 mm was used. Next, a PFA resin (manufactured by DuPont, dielectric constant 2.1) with a thickness of 0.21 mm was extruded and formed around the outer circumference of the center conductor 11 to have a solid structure as shown in FIG. 2(A), and the outer diameter was made 0.623 mm. Next, a horizontally wound shield 13 and a metal resin tape 14 were provided as the outer conductor. The horizontally wound shield 13 was formed as a single layer on the insulator 12. Specifically, it was formed by winding 38 silver-plated soft copper wires with an outer diameter of 0.05 mm in a left-handed direction at a pitch of 6.5 mm. The outer diameter after formation was 0.723 mm. Next, the metal resin tape 14 was wound on the horizontally wound shield 13. As the metal resin tape 14, a tape with a total thickness of 12 μm and a width of 3 mm, in which a copper foil with a thickness of 4 μm was provided on one surface of a PET substrate with a thickness of 8 μm, was used. This metal resin tape 14 was wound in a 1 / 3 lap (overlapping by a width of 1 mm) with the copper foil side on the inside (the side of the horizontally wound shield 13) in the opposite direction to the horizontally wound shield 13.

[0055] Next, a resin tape 15 with a total thickness of 4 μm and a width of 3 mm, having an adhesive layer with a thickness of 1 μm provided on one side, was wound with the adhesive layer side on the inside (the side of the metal resin tape 14). The winding form was a 1 / 3 lap (overlapping by a width of 1 mm) in the opposite direction to the metal resin tape 14. During the winding process, heating was applied to bond the adhesive layer and the metal resin tape 14. Then, as the extrusion sheath 16, a PFA resin (manufactured by DuPont) layer was extruded and formed with a thickness of 50 μm while being sucked by a vacuum pump, and a coaxial cable 10 with an outer diameter of 0.871 mm was fabricated. In this coaxial cable 10, the thickness T1 of the metal resin tape 14 and the thickness T2 of the resin tape 15 are such that T2 / T1 = 4 / 12 = 0.333.

[0056] [Example 2] In Example 1, a resin tape having a total thickness of 6 μm and a width of 3 mm, with a 1 μm thick adhesive layer provided on one side, was used as resin tape 15. A coaxial cable of Example 2 having an outer diameter of 0.877 mm was fabricated in the same manner as in Example 1 except for the above. In this coaxial cable 10, the thickness T1 of metal-resin tape 14 and the thickness T2 of resin tape 15 are such that T2 / T1=6 / 12=0.500.

[0057] [Example 3] In Example 1, a resin tape having a total thickness of 3 μm and a width of 3 mm, with a 1 μm thick adhesive layer provided on one side, was used as the resin tape 15. A coaxial cable of Example 3 having an outer diameter of 0.868 mm was fabricated in the same manner as in Example 1 except for the above. In this coaxial cable 10, the thickness T1 of the metal-resin tape 14 and the thickness T2 of the resin tape 15 are such that T2 / T1=3 / 12=0.250.

[0058] [Example 4] In Example 1, a resin tape having a total thickness of 8 μm and a width of 3 mm, with a 1 μm thick adhesive layer provided on one side, was used as resin tape 15. Otherwise, a coaxial cable 10 of Example 4 having an outer diameter of 0.883 mm was produced in the same manner as in Example 1. In this coaxial cable, the thickness T1 of metal-resin tape 14 and the thickness T2 of resin tape 15 are expressed as T2 / T1=8 / 12=0.667.

[0059] [Example 5] In Example 1, the metal-resin tape 14 used was a 12 μm-thick PET substrate with a 4 μm-thick copper foil provided on one side thereof, resulting in a total thickness of 16 μm and a width of 3 mm. A coaxial cable of Example 5 having an outer diameter of 0.883 mm was fabricated in the same manner as in Example 1 except for the above. In this coaxial cable 10, the thickness T1 of the metal-resin tape 14 and the thickness T2 of the resin tape 15 are such that T2 / T1=4 / 16=0.250.

[0060] [Example 6] In Example 1, the metal-resin tape 14 used was a 6 μm-thick PET substrate with a 4 μm-thick copper foil provided on one side thereof, resulting in a total thickness of 10 μm and a width of 3 mm. A coaxial cable of Example 6 having an outer diameter of 0.865 mm was fabricated in the same manner as in Example 1. In this coaxial cable 10, the thickness T1 of the metal-resin tape 14 and the thickness T2 of the resin tape 15 were such that T2 / T1=4 / 10=0.400.

[0061] [Example 7] In Example 1, the insulator 12 was a hollow structure. The hollow structure was formed by extruding PFA resin (manufactured by DuPont) at 350°C using a die nipple for forming hollow structures, to form a hollow structure having a cross-sectional shape in which a void was surrounded by an inner annular portion 12a having a thickness of 0.05 mm, an outer annular portion 12b having a thickness of 0.05 mm, and a connecting portion 12c having a thickness of 0.05 mm, and the void ratio was 54%. Except for this, the coaxial cable 10 of Example 7 was produced in the same manner as in Example 1.

[0062] [Example 8] In Example 1, two metal-resin tapes 14a and 14b were used as the metal-resin tape 14. The first metal-resin tape 14a had a total thickness of 10 μm and a width of 3 mm, with a 6 μm-thick PET base material and a 4 μm-thick copper foil provided on one side. Furthermore, a second metal-resin tape 14b had a total thickness of 12 μm and a width of 3 mm, with a 6 μm-thick PET base material and a 6 μm-thick copper foil provided on one side, and these were wound in reverse on top of the first. Otherwise, a coaxial cable of Example 8 having an outer diameter of 0.901 mm was fabricated in the same manner as in Example 1. In this coaxial cable 10, the thickness T1 (total: 22 μm) of the metal-resin tape 14 (two metal-resin tapes 14a and 14b) and the thickness T2 (4 μm) of the resin tape 15 were such that T2 / T1 = 4 / 22 = 0.182.

[0063] [Example 9] In Example 8, the first metal-resin tape 14a and the second metal-resin tape 14b were identical tapes with a total thickness of 10 μm and a width of 3 mm, each consisting of a 6 μm-thick PET substrate with a 4 μm-thick copper foil provided on one side. The two metal-resin tapes were wound in opposite directions. A coaxial cable of Example 9 with an outer diameter of 0.895 mm was fabricated in the same manner as in Example 1. In this coaxial cable 10, the thickness T1 (total of 20 μm) of the metal-resin tape 14 (two metal-resin tapes 14a and 14b) and the thickness T2 (4 μm) of the resin tape 15 were expressed as T2 / T1 = 4 / 20 = 0.200.

[0064] [Comparative Example 1] In Example 1, the resin tape 15 was not provided. Otherwise, the coaxial cable of Comparative Example 1 was produced in the same manner as in Example 1.

[0065] Comparative Example 2 In Example 1, a resin tape having a total thickness of 10 μm and a width of 3 mm, with a 1 μm thick adhesive layer provided on one side, was used as resin tape 15. A coaxial cable of Comparative Example 2 having an outer diameter of 0.889 mm was fabricated in the same manner as in Example 1. In this coaxial cable, the thickness T1 of metal-resin tape 14 and the thickness T2 of resin tape 15 were such that T2 / T1=10 / 12=0.833.

[0066] Comparative Example 3 In Example 1, a resin tape having a total thickness of 2 μm and a width of 3 mm, with a 1 μm thick adhesive layer provided on one side, was used as resin tape 15. A coaxial cable of Comparative Example 3 having an outer diameter of 0.856 mm was fabricated in the same manner as in Example 1. In this coaxial cable, the thickness T1 of metal-resin tape 14 and the thickness T2 of resin tape 15 were such that T2 / T1=2 / 12=0.166.

[0067] [evaluation] The step and appearance were visually evaluated. The step was mainly formed by the top layer tape, and was 4 μm in Examples 1, 5, 6, 7, 8, and 9, 6 μm in Example 2, 3 μm in Example 3, and 8 μm in Example 4, and 12 μm in Comparative Example 1 and 10 μm in Comparative Example 2. In Comparative Example 3, the top layer resin tape 15 was thin at 2 μm, and the underlying metal resin tape 14, which was 12 μm thick, had a large effect, resulting in an overall step of approximately 8 to 7 μm. In addition, in the results of Examples 1 to 9, T2 / T1 was within the range of 0.182 to 0.667.

[0068] The final appearance of the coaxial cable after the extruded sheath 16 was provided showed small variations in appearance in Examples 1 to 9, but these were smaller than those in Comparative Examples 1 to 3, and the terminal processing could be performed under the same conditions. In this way, it was visually confirmed that by reducing the step, the air layer was reduced, the appearance was improved, and the waviness in the longitudinal direction (variation in outer diameter) was reduced.

[0069] The flexibility of the coaxial cable was evaluated using the method shown in Figure 4. In the flexibility test, both ends of a 700 mm long coaxial cable 10 were fixed with fixtures 31, and the maximum width W was measured when no weight 32 was attached, and when a 2 g weight 32 was attached to the lowest point of the coaxial cable 10. The smaller the maximum width W, the more flexible the cable. When Examples 8 and 9 were evaluated, both were judged to have good flexibility. [Explanation of symbols]

[0070] 10 Coaxial Cable 11 Center conductor 12 Insulators 12a Inner ring 12b Outer ring 12c connection part 12' void 13 Horizontally wound shield 14 Metal-resin tape 14a First metal-resin tape 14b Second metal-resin tape 15 Resin tape 16 Extruded sheath 31 Fixtures 32 weight

Claims

1. A coaxial cable comprising a central conductor, an insulator provided on the outer periphery of the central conductor, an outer conductor provided on the outer periphery of the insulator, and a jacket covering the outer conductor, wherein the outer conductor is composed of a horizontally wound shield provided by horizontally winding metal fine wires around the outer periphery of the insulator, and a metal resin tape wound with the metal layer side facing inward on the horizontally wound shield, and the jacket is composed of a resin tape wound on the metal resin tape and an extrusion sheath covering the resin tape. When the thickness of the metal resin tape is T1 and the thickness of the resin tape is T2, T2 / T1 is in the range of 0.180 or more and 0.800 or less (excluding the case where T2 / T1 is 0.333). A coaxial cable characterized by this.

2. The coaxial cable according to claim 1, wherein the metal resin tape is composed of one or two sheets.

3. The coaxial cable according to claim 2, wherein when the metal resin tape is composed of two metal resin tapes, the thickness of the first metal resin tape is thinner than the thickness of the second metal resin tape.

4. The coaxial cable according to claim 2, wherein when the metal resin tape is composed of one metal resin tape, the thickness of the metal resin tape is 8 μm or more and 18 μm or less, and the thickness of the resin tape is 4 μm or more and 9 μm or less.

5. The coaxial cable according to claim 2 or 3, wherein when the metal resin tape is composed of two metal resin tapes, the total thickness of the two metal resin tapes is 16 μm or more and 26 μm or less, and the thickness of the resin tape is 4 μm or more and 9 μm or less.

6. The coaxial cable according to any one of claims 1 to 5, wherein the metal resin tape and the resin tape are wound around each other in the range of 1 / 4 lap to 1 / 2 lap.

7. The coaxial cable according to any one of claims 1 to 6, wherein an adhesive layer is provided on one surface of the resin tape, and the resin tape is wound so that the adhesive layer is on the inner side.

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