Coaxial flat cable

Abstract

To provide a coaxial flat cable that can suppress variation in impedance, and makes it easy to connect to a substrate while keeping a predetermined distance between coaxial cables.SOLUTION: In a coaxial flat cable 20 that comprises a plurality of coaxial cables 10 arranged spaced apart in a width direction X and a resin tape 11 for integrating at least terminal parts 21 of the coaxial cables 10 from one side or both sides, and in which each of the plurality of coaxial cables 10 is subjected to terminal processing and soldered to a substrate 30 or the like, a metal member 7 is arranged at least at a portion that becomes a coaxial structure of the coaxial cables 10 between the coaxial cables adjacent to each other, and the metal member 7 is constructed so as to be soldered to the substrate 30 or the like together with the coaxial cable 10, thereby the problem was solved. The metal member 7 is arranged such that its tip is positioned between a tip of a central conductor 1 and a tip side of a peel part or a peel-planned part of the outer conductor 3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a coaxial flat cable, and more particularly to a coaxial flat cable that is used inside or between electronic devices such as liquid crystal televisions and servers, can suppress fluctuations in impedance, and facilitates connection to a substrate with a uniform pitch of the coaxial cable.

Background Art

[0002] Flat cables are excellent in workability and flexibility and are widely used as internal wiring materials and external wiring materials for electronic devices. In particular, as a flat cable suitable for the propagation of high-frequency signals, a coaxial flat cable using a plurality of coaxial cables has been proposed. For example, Patent Document 1 proposes a coaxial flat cable having a large center conductor diameter, a small finished outer diameter, and stable high-frequency characteristics. This coaxial flat cable is a coaxial flat cable having a plurality of coaxial cables arranged in parallel at a predetermined interval and a fixing tape that integrates at least the terminal portions of the plurality of coaxial cables from one side or both sides. The coaxial cable includes at least a center conductor, a dielectric layer provided on the outer periphery of the center conductor and having a longitudinally continuous gap portion, an outer conductor provided on the outer periphery of the dielectric layer, and an insulating layer provided on the outer periphery of the outer conductor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional coaxial flat cable described above, each coaxial cable is subjected to terminal processing and connected to a substrate, a connector, or the like. The terminal processing of the coaxial cable involves peeling off the outer jacket to expose the outer conductor, and further peeling off the outer conductor and the insulator to expose the center conductor. The exposed outer conductor and center conductor are soldered to the corresponding substrate electrodes. At this time, there is a problem that impedance mismatch occurs in the portion where the outer conductor is peeled off, resulting in deteriorated transmission characteristics.

[0005] In addition, the coaxial cables are arranged according to the pitch of the substrate electrodes. However, the pitch is often larger than the outer diameter of the coaxial cable, and it is necessary to manufacture a coaxial flat cable with an appropriate gap between the coaxial cables. However, each coaxial cable is circular and is likely to shift, and it is difficult to maintain the gap between the coaxial cables at a predetermined interval so that stable soldering to the substrate electrodes is possible.

[0006] The present invention has been made to solve the above problems, and an object thereof is to provide a coaxial flat cable capable of suppressing fluctuations in impedance and maintaining a predetermined interval between coaxial cables to facilitate connection to a substrate.

Means for Solving the Problems

[0007] The coaxial flat cable according to the present invention includes a plurality of coaxial cables arranged side by side at intervals in the width direction, and a resin tape bonded to at least one side or both sides of at least the terminal portions of the plurality of coaxial cables to integrate the terminal portions. In the coaxial flat cable in which each of the plurality of coaxial cables is subjected to terminal processing and soldered to a substrate or a connector, a metal member is disposed at least in a portion having a coaxial structure of the coaxial cable between adjacent coaxial cables, and the metal member is soldered to the substrate or the connector together with the coaxial cable.

[0008] According to the present invention, since the metal member is disposed between adjacent coaxial cables and at least in a portion having a coaxial structure of the coaxial cable, it is disposed at least in a coaxial structure portion without an outer conductor (a portion where the insulator is exposed). And since such a metal member is soldered to a substrate or a connector together with the coaxial cable, it is connected as a common GND with the outer conductor of the coaxial cable. Therefore, it is possible to suppress fluctuations in impedance at the portion where the insulator is exposed. Further, since the metal member is disposed between adjacent coaxial cables, it is possible to keep a predetermined interval between the coaxial cables.

[0009] In the coaxial flat cable according to the present invention, the coaxial cable includes at least a center conductor, an insulator provided on the outer periphery of the center conductor, an outer conductor provided on the outer periphery of the insulator, and an outer covering provided on the outer periphery of the outer conductor.

[0010] According to the present invention, the coaxial structure portion where the metal member is disposed is arbitrarily disposed at the exposed portion of the center conductor that is no longer in the coaxial structure after terminal processing, but is necessarily disposed at the exposed portion of the insulator from which the outer conductor has been peeled off. As a result, it is possible to suppress fluctuations in impedance at least at the portion where the insulator is exposed.

[0011] In the coaxial flat cable according to the present invention, the metal member is disposed such that its tip is located between the tip of the center conductor and the tip side of the peeled portion or the planned peeled portion of the outer conductor.

[0012] In the coaxial flat cable according to the present invention, when the metal member is a metal wire, if the outer diameter of the metal wire is D1 and the outer diameter of the coaxial cable is D2, D1 / D2 is in the range of 0.5 to 1.5.

[0013] In the coaxial flat cable according to the present invention, the resin tape is (a) a cover tape that sandwiches the plurality of coaxial cables from both sides and integrates them, (b) a reinforcing tape provided at the terminal portions of the plurality of coaxial cables, or (c) a cover tape that sandwiches the plurality of coaxial cables from both sides and integrates them, and a reinforcing tape bonded to one side of the cover tape at the terminal portions of the plurality of coaxial cables.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a coaxial flat cable that can suppress fluctuations in impedance and facilitate connection to a substrate while maintaining a predetermined interval between coaxial cables.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

DETAILED DESCRIPTION OF THE INVENTION

[0016] Embodiments of the coaxial flat cable according to the present invention will be described with reference to the drawings. It should be noted that the present invention includes inventions having the same technical idea as the embodiments described below and the forms described in the drawings, and the technical scope of the present invention is not limited only to the descriptions of the embodiments and the drawings.

[0017] As shown in FIGS. 1 to 6, the coaxial flat cable 20 according to the present invention includes a plurality of coaxial cables 10 arranged side by side at intervals in the width direction X, and a resin tape 11 that integrates at least the terminal portions 21 of these coaxial cables 10 from one side or both sides. In the coaxial flat cable 20 in which each of the plurality of coaxial cables 10 is terminal-processed and soldered to a substrate 30 or the like, a metal member 7 is arranged at least at a portion having a coaxial structure of the coaxial cable 10 between adjacent coaxial cables, and the metal member 7 is soldered to the substrate 30 or the like together with the coaxial cable 10. This is the feature.

[0018] This coaxial flat cable 20 is arranged between adjacent coaxial cables where the metal member 7 is located at least in a portion having a coaxial structure of the coaxial cable 10, so it is at least arranged in a coaxial structure portion without an outer conductor 3 (a portion where the insulator 2 is exposed). And since such a metal member 7 is soldered to the substrate 30 or the connector together with the coaxial cable 10, it is connected as a common GND (the GND member is not shown) with the outer conductor 3 of the coaxial cable 10. Therefore, it is possible to suppress fluctuations in impedance at the portion where the insulator 2 is exposed. Further, since the metal member 7 is arranged between adjacent coaxial cables, the coaxial cables can be kept at a predetermined interval.

[0019] Hereinafter, each component of the coaxial flat cable will be described.

[0020] <Coaxial Cable> The coaxial cable 10 constitutes the coaxial flat cable 20, and as shown in FIGS. 1 to 3, a plurality of them are arranged side by side with a space in the width direction X. As shown in FIG. 5, the coaxial cable 10 includes at least a center conductor 1, an insulator 2 provided on the outer periphery of the center conductor 1, an outer conductor 3 provided on the outer periphery of the insulator 2, and an outer covering 4 provided on the outer periphery of the outer conductor 3. And as shown in FIGS. 6 to 9, after terminal processing of the terminal portion 21, the exposed center conductor 1 and outer conductor 3 are soldered to the electrodes 31, 32 of the substrate 30 or the connector.

[0021] (Center Conductor) As shown in FIGS. 5(A) and 5(B), the central conductor 1 is composed of a single strand extending in the longitudinal direction Y of the coaxial cable 10, or is composed of a plurality of strands twisted together. The type of the strand is not particularly limited as long as it is made of a highly conductive metal, but examples thereof preferably include highly conductive metal conductors such as copper wires, copper alloy wires, aluminum wires, aluminum alloy wires, and copper-aluminum composite wires, or those with a plating layer on their surfaces. From the perspective of high frequency, copper wires and copper alloy wires are particularly preferred. 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 preferred. The cross-sectional shape of the strand is not particularly limited either, and it may be circular or substantially circular, or may be square.

[0022] The cross-sectional shape of the central conductor 1 is not particularly limited either. It may be circular (including elliptical), rectangular, etc., but circular is preferred. The outer diameter of the central conductor 1 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 0.1 to 0.4 mm. In addition, each coaxial cable 10 is preferably within the range of 2.5 times or more and 10 times or less the outer diameter of the central conductor 1. An insulating coating (not shown) may be provided on the surface of the central conductor 1 as necessary. The type and thickness of the insulating coating are not particularly limited, but for example, those that decompose well during soldering are preferred, and a thermosetting polyurethane coating, etc. can be preferably cited.

[0023] (Insulator) As shown in Fig. 5, the insulator 2 is a low dielectric constant insulating layer continuously provided in the longitudinal direction on the outer periphery of the center conductor 1. The material of the insulator 2 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 colorant may be contained in the material of the insulator 2. The thickness of the insulator 2 is not particularly limited and is arbitrarily selected according to the required impedance characteristics, but it is preferably in the range of about 0.15 to 1.5 mm, for example. The forming method of the insulator 2 is not particularly limited, but any of a solid structure, a hollow structure, and a foamed structure can be easily formed by extrusion.

[0024] The insulator 2 may have a solid structure shown in Fig. 5(A), a hollow structure shown in Fig. 5(B), or a foamed structure (not shown). The hollow structure has a void portion 2A inside the structure body. For example, the void portion 2A can have a cross-sectional form surrounded by an inner annular portion 2B, an outer annular portion 2C, and a connecting portion 2D. When the hollow structure or the foamed structure is adopted, there is an additional effect that the material density of the insulator 2 becomes small and the insulator 2 can be made soft. The void portion 2A is continuously provided in the insulator 2, and its form may be circular or rectangular and is not particularly limited. Such a hollow-structured insulator 2 is excellent in side pressure strength, so it is not easily crushed during the manufacture of the coaxial cable 10 and the coaxial flat cable 20 or during the wiring operation of the coaxial flat cable 20, etc., and the high-frequency characteristics can be made stable. Note that the hollow-structured insulator 2 can be formed by resin extrusion on the outer periphery of the center conductor 1 running through the extrusion die. The thicknesses of the inner annular portion 2B, the outer annular portion 2C, and the connecting portion 2D are not particularly limited, but are, for example, in the range of about 0.01 mm to 0.05 mm, and the outer diameter of the formed hollow-structured insulator 2 can be, for example, in the range of about 0.4 mm to 1.0 mm.

[0025] (Outer Conductor) The outer conductor 3 is provided on the outer periphery of the insulator 2, and may be a braided thin wire, a horizontally wound one, a metal layer-attached insulating tape (such as a polyethylene terephthalate film with a copper layer, etc.), or a combination of both. In the example of Fig. 5, a horizontally wound thin wire 3A is provided on the outer periphery of the insulator 2, and an insulating tape 3B with a metal layer is further provided to cover it, but it is not limited to such a configuration. The thickness of the outer conductor 3 is not particularly limited, but is, for example, in the range of about 0.01 mm to 0.15 mm.

[0026] (Outer covering) The outer covering 4 is provided on the outer periphery of the outer conductor 3, and its material is not particularly limited as long as it is insulating. Preferably, as illustrated in Fig. 5, it can be configured by spirally winding an insulating tape 4A provided with an adhesive layer 4B on one side, but it is not limited to this form. As the adhesive layer 4B, various ones applied to the coaxial cable 10 can be used, and preferably, for example, a polyester-based thermoplastic adhesive resin, etc. can be mentioned. As the insulating tape 4A, polyester films such as polyethylene terephthalate films can be preferably mentioned. In particular, it is preferable to select a material with good adhesiveness to the resin tape 11 described later. For example, when the adhesive layer constituting the resin tape 11 is a polyester-based thermoplastic adhesive layer, the outer covering 4 is also preferably a polyester film. The overall thickness of the insulating tape 4A provided with the adhesive layer 4B on one side is preferably in the range of 0.03 mm or more and 0.1 mm or less.

[0027] (Others) The coaxial flat cable 20 may be provided with a shield layer (not shown) as necessary. The shield layer is provided, for example, on the resin tape 11 as shown in FIG. 1. Examples of the shield layer include a tape composed of at least a metal foil and a conductive adhesive layer provided on one surface of the metal foil, but the layer configuration is not particularly limited as long as it can exhibit a shielding function. Further, the shield layer can also act to keep the capacitance and external inductance between the center conductor and the shield layer uniform, and can prevent impedance mismatch in this portion.

[0028] <Metal member> As shown in FIGS. 1 to 4, the metal member 7 is an essential member constituting the coaxial flat cable 20. A plurality of coaxial cables 10 are arranged side by side at intervals in the width direction X, and the "interval" is ensured by the metal member 7. That is, the metal members 7 are arranged side by side in the width direction X between the coaxial cables 10, so that the coaxial cables 10 are provided at intervals. "At intervals" means that, as shown in FIGS. 1, 2, and 4(A)(B), when the metal members (metal wires) 7 are arranged side by side between the coaxial cables 10, and as shown in FIGS. 3 and 4(C), the two coaxial cables 10, 10 are a pair of closely adhered wires 10a, and the metal members (metal wires) 7 are arranged side by side between the pairs of wires 10a, 10a. It includes both cases. As long as there is a space provided through the metal member 7, other configurations may be used. For example, from one side in the width direction X, a coaxial flat cable 20 including single wires and pairs of the coaxial cable 10 such as a pair of wires 10a, a metal member 7, a coaxial cable 10, a metal member 7, a pair of wires 10a, a metal member 7,... may be used. Note that the metal member 7 may be located in the middle of the upper and lower cover tapes 11a as shown in FIG. 4(A), or may be in contact with the lower reinforcing tape 11b or the cover tape 11a as shown in FIGS. 4(B)(C). The metal member 7 thus arranged can keep a predetermined interval between the coaxial cables and facilitate connection to the substrate 30 or the like.

[0029] As shown in FIGS. 1 to 3, the metal member 7 is a metal wire. The cross-sectional shape of the metal wire is not particularly limited, but as shown in FIG. 4, it is preferably a circular round wire. When the outer diameter of the metal wire with a circular cross-section is D1 and the outer diameter of the coaxial cable 10 is D2, it is preferable that D1 / D2 is within the range of 0.5 to 1.5. By setting it within this range, the coaxial cable 10 and the metal wire can be adhered and fixed to the resin tape 11. On the other hand, when D1 / D2 is less than 1 / 2, the metal wire cannot adhere to the resin tape 11, and the interval between the coaxial cables may become unstable. When D1 / D2 exceeds 1.5, the resin tape 11 and the coaxial cable 10 do not adhere, and the necessary adhesive force may not be obtained.

[0030] In the longitudinal direction Y, as shown in FIGS. 6 and 8, the metal member 7 is disposed at least in a portion having a coaxial structure between adjacent coaxial cables. Since the "coaxial structure" does not refer to the coaxial structure only by the center conductor 1, the statement that "the metal member 7 is disposed at least in a portion having a coaxial structure" means that it is necessarily disposed in a portion where the insulator 2 is provided on the outer periphery of the center conductor 1. Therefore, the entire intermediate portion 22 of the coaxial cable 10 is included. In the terminal portion 21, as shown in FIGS. 6 and 8, the metal member 7 is necessarily disposed in a portion where the outer conductor 3 is exposed and a portion where the insulator 2 is exposed by terminal processing. Also, as shown in FIG. 8, it is not essential to dispose the metal member 7 in a portion of only the center conductor 1 that is not in the coaxial structure, but it may be optionally disposed. That is, the tip 7a of the metal member 7 is disposed so as to be located between the tip 1a of the center conductor 1 exposed after terminal processing and the tip side 3a of the tip peeling portion or the planned peeling portion of the insulator 2 exposed after terminal processing.

[0031] In this way, the metal member 7 is at least arranged in the coaxial structure portion (the portion having a coaxial structure) without the external conductor 3, and is soldered to the substrate 30 or the connector together with the external conductor 3 of the coaxial cable 10. By doing so, as shown in FIGS. 7 and 9, the metal member 7 is connected as a common GND (the GND member is not shown) with the external conductor 3 of the coaxial cable 10. Therefore, it is possible to suppress fluctuations in impedance at the portion where the insulator 2 is exposed.

[0032] The metal member 7 may be a single metal wire extending in the longitudinal direction Y of the coaxial cable 10, or may be a stranded wire formed by twisting a plurality of strands. In the case of a stranded wire, it is desirable that the strands do not fray and the outer diameter does not fluctuate. For example, it is preferable that fine wires coated with a solderable fused layer are twisted and then fused so as not to fray. The type of the strand is not particularly limited as long as it is made of a highly conductive metal, but highly 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 can be preferably mentioned. 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. An insulating coating (not shown) that can be soldered may be provided on the surface of the metal member 7 as necessary. The reason for using an insulating coating that can be soldered is to perform soldering together with the external conductor 3 of the coaxial cable 10m as shown in FIGS. 9 and 11. The type and thickness of the insulating coating that can be soldered are not particularly limited, but for example, those that decompose well during soldering are preferable, and a thermosetting polyurethane coating, etc. can be preferably mentioned. The outer diameter of the metal member 7 when the insulating coating is provided includes the thickness of the insulating coating.

[0033] As described above, the outer diameter of the coaxial cable 10 configured in this way is preferably in the range of about 0.1 to 0.4 mm, and preferably in the range of 2.5 times or more and 10 times or less the outer diameter of the center conductor 1.

[0034] <Resin tape> The resin tape 11 constitutes the coaxial flat cable 20. As shown in FIGS. 1 to 4, at least the terminal portions 21 of a plurality of coaxial cables 10 arranged at intervals in the width direction X are bonded together from one side or both sides to integrate the terminal portions 21. Examples of the resin tape 11 include the cover tape 11a shown in FIG. 1, the reinforcing tape 11b shown in FIG. 2, and the bonding of the cover tape 11a and the reinforcing tape 11b shown in FIG. 3, but it is not limited thereto. "At least" means that the resin tape 11 (11a, 11b, 11a and 11b) is always provided at the terminal portion 21, but the resin tape 11 (11a) may also be provided at the intermediate portion 22 other than the terminal portion. In addition, "both sides" refers to the upper and lower surfaces of a plurality of coaxial cables 10 arranged at intervals in the width direction X as shown in FIGS. 4(A) and 4(C), and "one side" refers to one surface (for example, the lower surface) of a plurality of coaxial cables 10 arranged at intervals in the width direction X as shown in FIG. 4(B).

[0035] (A) The resin tape 11 shown in FIGS. 1 and 4(A) is a cover tape 11a that sandwiches and integrates the entire plurality of coaxial cables from both sides. As shown in FIG. 1 and the like, the cover tape 11a is preferably bonded to all of the longitudinal direction Y of the plurality of coaxial cables 10, but it may be bonded only to the terminal portions 21 on both sides in the longitudinal direction Y and the intermediate portion 22 may be a non-integrated portion. The non-integrated portion allows the intermediate portion 22 to be easily deformed and can improve the degree of freedom during wiring in the electronic device. In the example of FIG. 1 and the like, two cover tapes 11a are sandwiched and bonded together from both sides to be integrated, but it may also be a structure in which one cover tape 11a is folded back and sandwiched and bonded together from both sides to be integrated.

[0036] (a) The resin tape 11 shown in FIGS. 2 and 4(B) is a reinforcing tape 11b provided at the terminal portion 21 of a plurality of coaxial cables 10. As shown in FIG. 2 and the like, the reinforcing tape 11b is provided only at the terminal portion 21 in the longitudinal direction Y of the plurality of coaxial cables 10, and the intermediate portion 22 is a non-integrated part. The non-integrated part allows the intermediate portion 22 to be easily deformed, improving the degree of freedom during wiring within the electronic device. Note that the length of the reinforcing tape 11b in the longitudinal direction Y is preferably about 5 to 20 mm, for example.

[0037] (b) The resin tape 11 shown in FIGS. 3 and 4(C) is composed of a cover tape 11a that sandwiches and integrates the entire plurality of coaxial cables from both sides, and a reinforcing tape 11b that is bonded to one side of the cover tape 11a at the terminal portion 21 of the plurality of coaxial cables 10. The cover tape 11a and the reinforcing tape 11b are the same as the structures described in (a) and (i).

[0038] (a) to (b), the above-mentioned cover tape 11a and reinforcing tape 11b are usually composed of a base material and an adhesive layer. For the cover tape 11a, the base material is not particularly limited, but a polyester film such as polyethylene terephthalate or polyethylene naphthalate can be preferably used. The thickness of the base material is arbitrarily selected within the range of about 0.025 mm to 0.1 mm. The adhesive layer is also not particularly limited, but it is preferably a material that can be adhesively bonded to the outer covering 4 to be bonded, and for example, a polyester-based thermoplastic adhesive resin layer can be preferably mentioned. The thickness of the adhesive layer is arbitrarily selected within the range of about 0.02 mm to 0.035 mm.

[0039] Regarding the reinforcing tape 11b, the base material is not particularly limited, and polyester films such as polyethylene terephthalate and polyethylene naphthalate, and polycarbonate films can be preferably used. These base materials are also excellent in dimensional stability, and have the advantage that dimensional changes are unlikely to occur even when subjected to fitting forces applied during connection to the connector, or when the temperature changes or time elapses. The thickness of the base material is arbitrarily selected within the range of about 0.025 mm to 0.3 mm. The adhesive layer is not particularly limited either, but it is preferably a material that can be adhesively bonded to the outer cover 4 to be bonded, and examples thereof include a polyester-based thermoplastic adhesive resin layer. The thickness of the adhesive layer is arbitrarily selected within the range of about 0.02 mm to 0.05 mm.

[0040] The bonding by the cover tape 11a and the reinforcing tape 11b is the combination of the cover tape 11a and the reinforcing tape 11b as shown in FIGS. 3 and 4(C), so the description thereof is omitted here.

Example

[0041] Hereinafter, the present invention will be described more specifically with reference to examples. Note that the present invention is not limited to the following examples.

[0042] [Fabrication of Coaxial Cable] For the coaxial cable 10, as the center conductor 1, an AWG32 (outer diameter of about 0.24 mm) obtained by twisting 7 silver-plated soft copper wires with a diameter of 0.08 mm was used. The insulator 2 was formed by extruding PFA resin (manufactured by DuPont) at 350°C using a die nipple for a hollow structure body, and as shown in FIG. 8(B), a hollow structure body having a cross-sectional shape in which the void portion 2A is surrounded by the inner annular portion 2B, the outer annular portion 2C, and the connecting portion 2D was formed. In this hollow structure body, the thickness of the inner annular portion 2B is 0.05 mm, the thickness of the outer annular portion 2C is 0.05 mm, the thickness of the connecting portion 2D is 0.05 mm, the outer diameter of the hollow structure body (insulator 2) is 0.60 mm, and the porosity of the void portion 2A is 30% with respect to the area of the entire insulator (entire hollow structure body). The dielectric constant ε was about 1.6.

[0043] The outer conductor 3 was formed by using 38 tinned soft copper wires with a diameter of 0.05 mm, and was wound around the outer periphery of the insulator 2 at a pitch of 12 mm using a horizontal winding shield machine to form a horizontally wound thin wire horizontal winding 3A. Further, a polyethylene terephthalate film with a copper layer having a thickness of 0.008 mm (insulating tape 3B with a metal layer) having a thickness of 0.004 mm was cut into a width of 2.5 mm, and using a tape winding machine, the copper layer was wound around the horizontally wound thin wire horizontal winding 3A side with a 1 / 3.5 lap. Next, a polyester tape (insulating tape 4A) having a thickness of 0.004 mm with a polyester thermoplastic resin (adhesive layer 4B) having a thickness of 0.001 mm provided on one side was cut into a width of 3.0 mm, and using a tape winding machine, the adhesive layer 4B was wound around the outer conductor side with a 1 / 3 lap.

[0044] [Coaxial flat cable] (Example 1) Sixteen coaxial cables 10 were prepared. Between each coaxial cable 10, as shown in FIGS. 1 and 4(A), after arranging them side by side via a copper wire with a diameter of 0.5 mm as the metal member 7, as shown in FIG. 1, the cover tape 11a was used to bond and integrate the entire surface from both sides to form the coaxial flat cable 20 shown in FIG. 4(A). The cover tape 11a was a polyethylene terephthalate film substrate with a thickness of 0.025 mm having a polyester thermoplastic resin (adhesive layer) with a thickness of 0.035 mm provided on one side, which was cut into a width of 25 mm. The coaxial flat cable 20 was cut to a predetermined length, and the terminal portion 21 was processed as shown in FIG. 6 to expose the center conductor 1, the insulator 2, and the outer conductor 3. Note that the longitudinal direction Y of the metal member 7 was arranged such that its tip 7a was at the same length as the tip 1a of the center conductor 1, as shown in FIG. 6.

[0045] The obtained coaxial flat cable 20 was attached to the substrate 30 as shown in FIG. 9. The attachment was performed by soldering the center conductor 1 to the solder connection portion 41 and soldering the outer conductor 3 and the metal member 7 to the solder connection portion 42.

[0046] (Example 2) Sixteen of the obtained coaxial cables 10 were prepared. As shown in FIGS. 2 and 4(B), between each of the coaxial cables 10, they were arranged side by side via a copper wire with a diameter of 0.5 mm as the metal member 7, and then the reinforcing tape 11b was bonded to one side on the terminal portion 21 side to be integrated, resulting in the coaxial flat cable 20 shown in FIG. 4(B). The reinforcing tape 11b used was a polyethylene terephthalate film substrate with a thickness of 0.125 mm provided with a polyester thermoplastic resin (adhesive layer) with a thickness of 0.042 mm on one side, which was cut in the width direction X of 25 mm and the longitudinal direction Y of 10 mm. The coaxial flat cable 20 was cut to a predetermined length, and the terminal portion 21 was processed as shown in FIG. 8, exposing the center conductor 1, the insulator 2, and the outer conductor 3 respectively. Note that the longitudinal direction Y of the metal member 7 was arranged such that its tip 7a was at the same length as the tip 2a of the insulator 2, as shown in FIG. 8.

[0047] The obtained coaxial flat cable 20 was attached to the substrate 30 as shown in FIG. 9. The attachment was performed by soldering the center conductor 1 to the solder connection portion 41 and soldering the outer conductor 3 and the metal member 7 to the solder connection portion 42.

[0048] (Example 3) Sixteen of the obtained coaxial cables 10 were prepared. As shown in FIGS. 3 and 4(C), the coaxial cables 10 were made into pairs of two as pair wires 10a, and between the pair wires 10a, they were arranged side by side via a copper wire with a diameter of 0.5 mm as the metal member 7. Then, as shown in FIG. 3, the cover tape 11a was bonded to the entire surface from both sides to be integrated, and further the reinforcing tape 11b was bonded to the terminal portion 21 on one side of the cover tape 11a, resulting in the coaxial flat cable 20 shown in FIG. 4(C). The cover tape 11a and the reinforcing tape 11b used were the same as those in Example 1 and Example 2 respectively. The coaxial flat cable 20 was cut to a predetermined length, and the terminal portion 21 was processed in the same manner as in FIGS. 6 and 8, exposing the center conductor 1, the insulator 2, and the outer conductor 3 respectively. Note that the longitudinal direction Y of the metal member 7 was arranged such that its tip 7a was at the same length as the tip 1a of the center conductor 1, as in FIG. 6.

[0049] The obtained coaxial flat cable 20 was attached to the substrate 30 in the same manner as in FIG. 6. The attachment was performed by soldering the center conductor 1 to the solder connection portion 41 and soldering the outer conductor 3 and the metal member 7 to the solder connection portion 42.

[0050] (Comparative Example 1) Sixteen obtained coaxial cables 10 were prepared. As shown in FIG. 10, each coaxial cable 10 was arranged in parallel at regular intervals and then integrated by laminating the entire surface from both sides with a cover tape 11a to form a coaxial flat cable 20. The cover tape 11a used was the same as that in Example 1. The coaxial flat cable 20 was cut to a predetermined length, and the terminal portion 21 was processed as shown in FIG. 10 to expose the center conductor 1, the insulator 2, and the outer conductor 3, respectively.

[0051] The obtained coaxial flat cable 20 was attached to the substrate 30 as shown in FIG. 11. The attachment was performed by soldering the center conductor 1 to the solder connection portion 41 and soldering the outer conductor 3 to the solder connection portion 42.

Explanation of Reference Numerals

[0052] 1 Center conductor 1a Center conductor tip 2 Insulator 2a Insulator tip 2A Gap portion 2B Inner annular portion 2C Outer annular portion 2D Connecting portion 2E Gap portion 3 Outer conductor 3a Outer conductor tip 3A Fine wire spiral winding 3B Insulating tape with metal layer 4 Outer covering 4A Insulating tape 4B Adhesive layer 7 Metal member 7a Metal member tip 9 Impedance mismatch portion 10 Coaxial cable 10a Pair wire 11 Resin tape 11a Cover tape 11b Reinforcing tape 20 Coaxial flat cable 21 Terminal part 22 Intermediate part 30 Substrate 31 Electrode 32 Electrode 41 Solder connection part of center conductor 42 Solder connection part of outer conductor X Width direction Y Longitudinal direction

Claims

1. A coaxial flat cable having a plurality of coaxial cables arranged at intervals in the width direction, and a resin tape bonded to at least one side or both sides of at least the terminal side of the intermediate portion other than the terminal portions of the coaxial cables to integrate at least the terminal side. In the coaxial flat cable in which each of the coaxial cables is terminated and soldered to a substrate or a connector, a metal member is disposed between each of the plurality of coaxial cables in a form in contact with adjacent coaxial cables to secure the interval. The metal member is disposed at least in a portion having a coaxial structure in the longitudinal direction of the coaxial cable, and the metal member is soldered to the common GND of the substrate or the connector together with the outer conductor of the coaxial cable. A coaxial flat cable characterized by the above.

2. The coaxial cable according to claim 1, further comprising at least 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 an outer covering provided on the outer periphery of the outer conductor.

3. The coaxial flat cable according to claim 2, wherein the metal member is disposed at least in a portion where the insulator is provided on the outer periphery of the central conductor, and the tip thereof is disposed between the tip of the central conductor and the tip side of the peeled portion or the planned peeled portion of the outer conductor.

4. When the metal member is a metal wire, when the outer diameter of the metal wire is D1 and the outer diameter of the coaxial cable is D2, D1 / D2 is in the range of 0.5 to 1.

5. The coaxial flat cable according to any one of claims 1 to 3.

5. The resin tape is (a) a cover tape that sandwiches and integrates the intermediate portion of the coaxial cable from both sides, (b) a reinforcing tape provided on the terminal side of the intermediate portion of the coaxial cable, or (c) a cover tape that sandwiches and integrates the intermediate portion of the coaxial cable from both sides, and a reinforcing tape bonded to one side of the cover tape on the terminal side of the intermediate portion of the coaxial cable. The coaxial flat cable according to any one of claims 1 to 4.

Images