JP2008258172A - Coaxial cable strand, coaxial cable, and coaxial cable bundle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coaxial cable strand, a coaxial cable, and a coaxial cable bundle with enough bending resistance, capable of effectively preventing a break or a short circuit of a connecting part, and excellent in economical efficiency. <P>SOLUTION: The coaxial cable strand 1 is provided with a center conductor 11, an insulator 12 covering the center conductor 11, and an outer conductor 13 covering the insulator 12. The center conductor 11 is formed of a single wire formed of a metal material containing copper and silver with a tensile strength of 120 kgf/mm<SP>2</SP>or higher and a conductivity of 60 to 90%IACS. Moreover, the coaxial cable 2 and the coaxial cable bundle are provided with the coaxial cable strands 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coaxial cable strand, a coaxial cable, and a coaxial cable bundle, and in particular, includes a coaxial cable strand used for a coaxial cable for transmitting an electric signal, a coaxial cable including the coaxial cable strand, and the coaxial cable. Coaxial cable bundle.

Use ultrasonic diagnostic equipment such as diagnostic probes and endoscopes, medical devices such as endoscopes, signal transmission wire cables used in industrial robots, and internal connection wire cables used in information devices such as notebook computers. By being repeatedly bent in, strain may accumulate and eventually break. Therefore, as a central conductor of a coaxial cable (or an element wire) used as such an electric cable, an electric wire (so-called stranded wire) in which a large number of conductor elements are stranded is widely used in order to improve the bending resistance. ing. As an example of such a coaxial cable, Japanese Patent Laid-Open No. 9-35541 discloses an electric wire made of a fiber reinforced copper matrix composite conductor and a cable using the electric wire.
Japanese Patent Laid-Open No. 9-35541

  However, the coaxial cable having the stranded wire as the central conductor as described above is excellent in flexibility, but the contact wire failure occurs due to the collapse of the arrangement of the conductor wires at the time of the pressure contact, and there is a risk of disconnection at the time of use. . In addition, when the central conductor is soldered to a circuit board having a narrow pitch pattern, the conductor strands are scattered, which may cause a short circuit. Therefore, the connection processing work of such a coaxial cable terminal is extremely complicated including inspection. In addition to such problems, since it takes time to manufacture the stranded wire, there has been a demand for a coaxial cable that has excellent bending resistance and can reduce manufacturing and connection processing costs.

  Therefore, the present invention has been made in view of such circumstances, and while having sufficient bending resistance, it is possible to effectively prevent disconnection and short-circuiting of the connecting portion, and is excellent in economic efficiency. It aims at providing a coaxial cable strand, a coaxial cable, and a coaxial cable bundle.

In order to solve the above-mentioned problems, the present inventors have conducted extensive research and found that there is a close relationship between the material and tensile strength of the central conductor and the bending resistance of the electric wire, and reached the present invention. That is, the coaxial cable strand of the present invention is a coaxial cable strand comprising a center conductor, an insulator covering the periphery of the center conductor, and an outer conductor covering the periphery of the insulator, The central conductor is formed of a single wire made of a metal material containing copper and silver, has a tensile strength of 120 kgf / mm ² or more, and a conductivity of 60 to 90% IACS. And

  The cable strands and cables used in the above applications are required to have high bending resistance, but conventional single wires made of a metal material containing copper are required to have a short bending life (number of times of bending to break). The bending resistance cannot be sufficiently satisfied. However, according to the coaxial cable strand of the present invention configured as described above, it has been found that the bending life is extremely long even though a single wire is used as the central conductor. In general, the fatigue limit increases as the tensile strength increases, but it has also been found that the flexural properties are superior in flexural properties.

Further, the plastic elongation of the central conductor is expressed by the following formula (1);
0.2% ≦ L ≦ 2.0% (1)
[Wherein L represents plastic elongation (%). ]
It is preferable to satisfy the relationship represented by: When a coaxial cable bending test was performed using a conductor having a different tensile elongation at 120 kgf / mm ² and the same tensile strength, the plastic elongation was in the range of the above formula (1). It has been found that a coaxial cable using a center conductor has a longer bending life and superior bending characteristics than a coaxial cable using a center conductor having only a plastic elongation below the lower limit of the range. This tendency was more conspicuous in the coaxial cable in which the central conductor according to the present invention is a single wire than in the conventional coaxial cable in which the central conductor is a stranded wire. In the bending test, a strain equal to or greater than the plastic elongation is applied to the surface of the central conductor, and it is considered that the plastic elongation of the central conductor according to the present invention is larger than that of the conventional one under a special form of a coaxial cable. Therefore, under such conditions, the generation of cracks in the surface portion of the central conductor that receives the largest strain and the propagation of the cracks are more suppressed in the central conductor constituting the coaxial cable strand according to the present invention. It is estimated that.

  Furthermore, since the central conductor is a single wire, there is no pressure welding failure due to the collapse of the arrangement during pressure welding. Therefore, disconnection at the time of use of a coaxial cable strand can fully be prevented. Furthermore, when the center conductor is soldered to a circuit board having a narrow pitch pattern, the center conductor does not come apart. Therefore, it is possible to sufficiently prevent the occurrence of a short circuit. Therefore, the burden of the inspection at the time of connection can be reduced, and the work man-hours for connecting the coaxial cable strands can be significantly reduced. Furthermore, since the central conductor is a single wire, when the conditions such as pressing pressure are constant when the end of the coaxial cable strand is pressed and deformed by a press or the like, the cross-sectional shape of the central conductor is uniform, that is, uniform. It is transformed to become. Accordingly, a plurality of coaxial cable strands can be reliably and collectively connected to a connection point such as a substrate, for example, so that an integrated circuit (IC) is inserted into the substrate. As a result, it is possible to further reduce the work man-hours for connecting the coaxial cable strands.

  Furthermore, since the conductivity is in the above range, it is possible to prevent an increase in transmission loss due to Joule heat generated inside the central conductor when the signal is transmitted because the conductivity is too small. In addition, since an increase in transmission loss due to generation of Joule heat during signal transmission can be prevented, it is not necessary to increase the diameter of the central conductor in order to suppress such transmission loss. In addition, conductivity and tensile strength tend to contradict each other, but by including a predetermined amount of silver in the copper as a component of the metal material, the conductivity and tensile strength in the above range are simultaneously expressed in the central conductor. It is considered possible. In addition, if the insulator is a flexible member, the possibility of the insulator breaking when the coaxial cable strand is bent can be reduced.

  Furthermore, the silver content in the metal material is more preferably 2 to 10% by weight. By using a metal material having such a composition, for example, a central conductor is manufactured by a method similar to the manufacturing method of a normal wire, thereby obtaining a single-wire central conductor having the above tensile strength and conductivity. be able to. Therefore, it is ensured that the bending characteristics of the coaxial cable strands are remarkably improved, and the occurrence of pressure welding failure and short circuit during the connection process is surely prevented, and the work man-hours in the connection process can be significantly reduced. .

Furthermore, the present inventors have conducted research on the fracture mechanism of each of the central conductor and the outer conductor, and have found a condition for obtaining good bending resistance. That is, it is preferable that the tensile strength of the central conductor and the tensile strength of the outer conductor satisfy the relationship represented by the following formula (2).
Tg ≦ Tc ≦ Tg × 3 (2)
[In the formula, Tc represents the tensile strength of the central conductor, and Tg represents the tensile strength of the outer conductor. ]
Thus, when the value of Tc is in the above range, when the coaxial cable strand is bent, stress is prevented from concentrating on one of the bent portions of the center conductor and the outer conductor. One plastic deformation does not become larger than the other. As a result, it is possible to prevent the bending resistance of one of the center conductor and the outer conductor from becoming extremely lower than the other.

  Furthermore, the outer diameter (diameter) of the center conductor is preferably 0.010 to 0.2 mm, and more preferably 0.020 to 0.15 mm. In general, since the bending test is performed with the same load and the same mandrel diameter (the diameter of the metal rod) (see the description of the bending test method described later), if the outer diameter of the central conductor is less than 0.010 mm, Since the stress applied to the conductor increases, the bending life tends to be reduced. On the other hand, if the outer diameter exceeds 0.2 mm, the strain applied to the central conductor increases, and the flexing life tends to decrease in the same manner.

  A coaxial cable according to the present invention includes the coaxial cable strand according to the present invention and an outer covering member covering the periphery of the coaxial cable strand. As described above, the bending resistance of the coaxial cable strand of the present invention is remarkably improved, and if a member having flexibility is used for the outer skin member, a coaxial cable having sufficiently excellent bending resistance can be obtained. Can do. In addition, since the process of connecting the coaxial cable strands is extremely simple, the number of work steps for connecting the coaxial cable to the board or the connector can be significantly reduced.

  Furthermore, the coaxial cable of the present invention preferably includes a plurality of the coaxial cable strands according to the present invention, and each coaxial cable strand is preferably arranged in parallel inside the outer skin member. If it does in this way, the coaxial cable excellent in the bending resistance with respect to the bending around the axis along the parallel direction of a coaxial cable strand can be obtained. Further, the thickness of the coaxial cable can be reduced as compared with the case where the coaxial cable strands are not arranged in parallel, and therefore, it can be installed in a narrow part in the device.

  The coaxial cable bundle of the present invention includes a plurality of coaxial cables according to the present invention, and each coaxial cable is disposed inside the outer cover member. In this way, the bending resistance of the coaxial cable according to the present invention is sufficiently excellent, and the coaxial cables can be assembled and arranged. Therefore, if a flexible member is used for the outer cover member, A coaxial cable bundle having the same or higher bending resistance is obtained. In addition, since the end of the coaxial cable strand can be processed into a uniform shape, the coaxial cable bundle can be reliably and easily connected to the connection point of the board or the connector. Therefore, it is possible to reduce the work man-hours required for the coaxial cable bundle connection process.

The “tensile strength” and “plastic elongation” in the present invention are defined in JIS C 3002 and are sometimes referred to as “tensile strength”. The unit conversion of “tensile strength” can be performed, for example, according to the relationship shown in the following formula (3).
1 kgf / mm ² = 9.807 MPa (3)
“Conductivity” is a value defined in JIS C 3001, and “IACS” is an abbreviation for International Annealed Copper Standard. Furthermore, the “bending test” is performed according to the following method.

<Bending test method 1>
FIG. 5 is a schematic diagram for explaining a bending test (so-called left / right bending test) in the present invention. First, the center portion of the test body 100 of the central conductor is sandwiched between two metal rods 51 (outer diameter 2 mm), and a 5 g weight 52 is attached to the lower end of the test body 100. Next, in this state, the upper half of the test body 100 is bent so as to be wound around each metal rod 51 by 90 °. It should be noted that one bend on each of the left and right sides is taken as one time, bent at a frequency of 30 times / minute, and the number of times that the test specimen is bent is measured.

<Bending test method 2>
Except that a multi-core coaxial cable (coaxial cable bundle) is used as the test body 100, the outer diameter of the metal rod 51 is 25.4 mm, and the weight of the weight 52 is 500 g, the same as in the bending test 1 described below. Measure for the item.
(1) Number of bends until center conductor or outer conductor breaks (2) Presence or absence of dielectric breakdown after 300,000 bends: When a DC voltage of 1000 V is applied between the center conductor and outer conductor of test body 100 Evaluation is based on the current value.

  According to the present invention, a coaxial cable strand, a coaxial cable, and a coaxial cable bundle that are capable of effectively preventing disconnection and short-circuiting of a connecting portion while having sufficient bending resistance, and excellent in economic efficiency. Obtainable.

  Hereinafter, preferred embodiments of a coaxial cable strand, a coaxial cable, and a coaxial cable bundle according to the present invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted.

<Coaxial cable strand and coaxial cable>
FIG. 1 is a perspective view showing an embodiment of the coaxial cable of the present invention, and FIG. 2 is a sectional view thereof. As shown in the figure, the coaxial cable 2 is configured such that the coaxial cable element 1 is coaxially arranged inside a cylindrical outer skin 21 (outer skin member). In this coaxial cable element 1, the periphery of a central conductor 11 formed of a single wire made of a metal material is covered with an insulator 12, and the periphery of the insulator 12 is covered with an external conductor 13. . Hereinafter, each of these components will be described in detail.

The center conductor 11 is a single wire made of a metal material mainly containing copper and containing silver. The silver content in the metal material is preferably 2 to 10% by weight, more preferably 2 to 6% by weight, and particularly preferably 3 to 5% by weight. The metal material having such a composition is excellent in conductivity, and in the above preferred composition range, it is possible to reliably achieve a tensile strength of 120 kgf / mm ² or more and an electrical conductivity of 60 to 90% IACS. .

The method for producing the metal material is not particularly limited. For example, a predetermined amount of copper and silver bullion are melted and cast into an ingot, and the ingot is hot or cold processed. The center conductor 11 which is a single wire having a tensile strength of 120 to 160 kgf / mm ² can be obtained by performing linear heat treatment and further performing heat treatment and cold working.

  On the other hand, the electrical conductivity of the central conductor 11 is 60 to 90% IACS, similar to the metal material. If this conductivity is less than 60% IACS, the Joule heat generated inside the central conductor during signal transmission tends to increase and transmission loss tends to become significant. On the other hand, if the conductivity exceeds the above upper limit, It is necessary to change the composition of the metal material, particularly the silver content, and as a result, it tends to be difficult to maintain the tensile strength of the central conductor 11 in the above range. Further, as described above, the electrical conductivity and the tensile strength tend to conflict with each other. However, by setting the metal material composition to the above preferable range, the high electrical conductivity and the large tensile strength in the central conductor 11 are obtained. This can be achieved simultaneously and reliably.

The plastic elongation of the center conductor 11 is preferably the following formula (1);
0.2% ≦ L ≦ 2.0% (1)
[Wherein L represents plastic elongation (%). ]
The relationship represented by is satisfied. When a material having the same tensile strength is used for the central conductor, a coaxial cable strand and a coaxial cable having better bending resistance can be obtained when the plastic elongation is larger. In particular, in the coaxial cable strand 1 and the coaxial cable 2 in which the central conductor 11 is a single wire, this tendency is more significant than in a coaxial cable in which the central conductor is a stranded wire. In general, the bending test is often performed under the condition that the strain applied to the central conductor is 0.2% or more, and the strain applied to the single wire is larger than that of the conventional stranded wire. It is estimated that.

  Furthermore, the outer diameter of the center conductor 11 is preferably 0.010 to 0.2 mm, particularly preferably 0.020 to 0.15 mm. If the outer diameter is less than 0.010 mm, the stress applied to the central conductor 11 increases, and the flex life of the coaxial cable strand 1 and the coaxial cable 2 tends to be reduced. On the other hand, when the outer diameter exceeds 0.2 mm, the strain applied to the center conductor 11 increases, and the flexing life tends to decrease in the same manner.

  The insulator 12 is made of a material having flexibility and insulation, and the material is not particularly limited. For example, the epoxy resin, the polyester resin, the polyurethane resin, and the polyvinyl alcohol type are used. Resins, vinyl chloride resins, vinyl ester resins, acrylic resins, epoxy acrylate resins, diallyl phthalate resins, phenol resins, polyamide resins, polyimide resins, melamine resins, and other organic materials Fibers or inorganic fibers made of inorganic substances can be used, and these can be used alone or in combination of two or more. Specifically, a fluorine-based resin such as polyethylene terephthalate is preferably used. The insulator 12 is formed by, for example, arranging the center conductor 11 in a mold having a cylindrical hollow portion and extruding the resin material around the center conductor 11 to form the insulator 12 as shown in FIG. It is formed into a shape.

  The outer conductor 13 can be appropriately selected from flexible outer conductors (so-called shields) that are generally used in thin coaxial cables. Such an external conductor 13 can be formed, for example, by laterally winding a thin and thin tape-like conductor or a thin conductor wire around the outer periphery of the insulator 12 covered around the center conductor 11. Moreover, you may twist together the thin wire (for example, litz wire) twisted along the outer periphery of the insulator 12, as shown in FIG. In the present invention, as shown in FIG. 1, a state in which an insulator 12 and an outer conductor 13 are provided around the center conductor 11 (outer peripheral surface) is referred to as a coaxial cable element 1.

  In addition, the outer skin 21 can be appropriately selected and used from outer skin members generally used in coaxial cables. For example, the outer resin 21 has the thermoplasticity among the above-described resin materials, or is made of another thermoplastic material. It is formed by sandwiching or winding the element wire 1 and then heat welding. Further, similarly to the method for forming the insulator 12 described above, a resin material may be extruded around the coaxial cable strand 1. Further, it is possible to use a thermosetting material processed into a cylindrical shape as the outer skin 21, and the coaxial cable strand 1 can be accommodated in the outer skin 21. However, the coaxial cable strand 1 of the present invention has a thin wire diameter. In some cases, the two methods are simple and preferable.

Furthermore, in the coaxial cable strand 1, the tensile strength of the center conductor 11 and the tensile strength of the outer conductor 13 satisfy the relationship represented by the following formula (2).
Tg ≦ Tc ≦ Tg × 3 (2)
[In the formula, Tc represents the tensile strength of the center conductor 11, and Tg represents the tensile strength of the outer conductor 13. ]
When the value of Tc is in the above range, when the coaxial cable strand 1 is bent, stress is prevented from concentrating on one of the bent portions of the center conductor 11 and the outer conductor 13, and either One plastic deformation does not become larger than the other. Therefore, the bending resistance of one of the center conductor 11 and the outer conductor 13 is prevented from becoming extremely lower than the other. As a result, the bending resistance of the coaxial cable strand 1 can be further improved.

  According to the coaxial cable strand 1 and the coaxial cable 2 configured as described above, the following operational effects are exhibited. That is, since the metal material forming the central conductor 11 contains copper as a main component and silver, a phase containing copper as a main component and a phase containing silver as a main component are generated during casting. The center conductor 11 manufactured by the above-described method or the like exhibits a very thin fibrous structure in both of the two types of phases described above. As a result, the mechanical strength of the center conductor 11 is increased, and the tensile strength of the center conductor 11 is significantly increased. Therefore, the center conductor 11 having both high tensile strength and high conductivity, which are usually contradictory properties, can be obtained. And since the tensile strength of the center conductor 11 is fully raised (tensile strength is the above-mentioned range), while a fatigue limit becomes large, a bending characteristic can be improved. Therefore, although the center conductor 11 is a single wire, the coaxial cable strand 1 and the coaxial cable 2 having sufficient bending resistance can be obtained. When the silver content in the metal material is 2 to 10% by weight, the high tensile rigidity and high conductivity of the central conductor 11 tend to be surely exhibited. 2 can be reliably and sufficiently improved in bending resistance and conductivity.

  Further, since the conductivity of the center conductor 11 is sufficiently increased (the conductivity is in the above range), an increase in transmission loss due to Joule heat generated inside the center conductor 11 during signal transmission is prevented. . Therefore, the coaxial cable strand 1 and the coaxial cable 2 having excellent transmission characteristics can be obtained. Furthermore, since an increase in transmission loss due to generation of Joule heat during signal transmission can be prevented, there is no need to increase the diameter of the central conductor 11 in order to suppress such transmission loss. Therefore, the coaxial cable strand 1 and the coaxial cable 2 can be thinned, and the installation in a narrow part in the device and the installation density thereof can be increased. In addition, the coaxial cable element 1 and the coaxial cable 2 can be reduced in weight.

  Further, since the central conductor 11 is a single wire, there is no pressure contact failure due to the collapse of the arrangement at the time of pressure contact, and disconnection during use of the coaxial cable strand 1 and the coaxial cable 2 is prevented. Further, when the center conductor 11 is soldered to the circuit board having a narrow pitch pattern, the center conductor 11 does not come apart, so that a short circuit is prevented from occurring at this connection portion. Therefore, since the work man-hour when connecting the coaxial cable element 1 or the coaxial cable 2 can be significantly reduced, it is possible to improve the economics related to the connecting process. Furthermore, since the central conductor 11 is a single wire, the cross-sectional shape of the central conductor 11 is uniform if the conditions such as pressure are constant when the end of the coaxial cable strand 1 or the coaxial cable 2 is subjected to pressure deformation. Transformed into Therefore, it becomes possible to connect a plurality of coaxial cable strands 1 or coaxial cables 2 to a connection point such as a substrate reliably and extremely easily in a lump. As a result, the man-hours for connecting the coaxial cable element 1 and the coaxial cable 2 can be further reduced, so that the economy related to the connecting process can be further improved.

  Furthermore, since the plastic elongation of the center conductor 11 preferably satisfies the relationship represented by the above formula (1), the occurrence of cracks in the center conductor 11 and its propagation are suppressed. Therefore, the bending resistance of the coaxial cable strand 1 and the coaxial cable 2 can be further enhanced.

  Furthermore, when the outer diameter of the center conductor 11 is preferably 0.010 to 0.2 mm, particularly preferably 0.020 to 0.15 mm, an increase in stress applied to the center conductor 11 can be suppressed. The increase in strain applied to the central conductor 11 can be suppressed. Therefore, the bending resistance of the coaxial cable strand 1 and the coaxial cable 2 can be further improved. Further, even when a constant tension is applied to the coaxial cable strand 1 and the coaxial cable 2, the coaxial cable strand 1 and the coaxial cable 2 can be prevented from being broken sufficiently against the tension.

  Moreover, since the insulator 12 has flexibility, the possibility that the insulator 12 breaks when the coaxial cable strand 1 is bent is reduced. Therefore, the possibility that the center conductor 11 and the outer conductor 13 are electrically connected is reduced, and the electromagnetic shield characteristics of the coaxial cable element 1 and the coaxial cable 2 can be maintained well even if the bending is repeated. In addition, since the outer skin 21 has flexibility, the coaxial cable 2 can maintain the excellent bending resistance of the coaxial cable strand 1 and obtain sufficient bending resistance.

  Next, FIG. 3 is a sectional view showing another embodiment according to the coaxial cable of the present invention. As shown in FIG. 3, in the coaxial cable 3, a plurality of coaxial cable strands 1 are arranged in parallel inside a flexible outer skin 31 (outer skin member). The material used for the outer skin 31 can be appropriately selected from the same materials as those used for the outer skin 21 described above. The outer skin 31 can be formed in the same manner as the outer skin 21 except for covering the periphery of the plurality of coaxial cable strands 1.

  In the coaxial cable 3 configured in this way, since the outer sheath 31 has flexibility, the flexibility of the coaxial cable strand 1 is maintained, and bending around the axis along the parallel direction of the coaxial cable strand 1 is maintained. The resistance to bending is excellent. Further, the thickness of the coaxial cable 3 can be reduced as compared with the case where the coaxial cable strands 1 are not arranged in parallel. Therefore, it can be installed in a narrow part in the device. In addition, since the end of the coaxial cable strand 1 can be processed into a uniform shape, the coaxial cable 3 can be reliably and easily connected to the connection point of the board or the connector. Therefore, the work man-hours required for the connection process of the coaxial cable 3 can be reduced.

<Multi-core coaxial cable>
FIG. 4 is a cross-sectional view showing an embodiment of the coaxial cable bundle of the present invention. The multi-core coaxial cable 4 as a coaxial cable bundle is arranged such that a plurality of coaxial cables 2 are gathered inside a flexible outer jacket 41 (outer jacket member). The outer cannula 41 is formed by covering a cylindrical inner outer cannula 41a having electromagnetic shielding characteristics with a cylindrical outer outer cannula 41b made of a resin material. The inner jacket 41a can be formed in the same manner as the outer conductor 13 (see FIGS. 1 and 2) constituting the coaxial cable strand 1, while the outer jacket 41b is a jacket 31 (see FIG. 1) constituting the coaxial cable 3. 3) and the same material and method.

  In the multi-core coaxial cable 4 configured in this way, since the outer jacket 41 has flexibility, the flexibility of the coaxial cable 2 is maintained. Therefore, the bending resistance equal to or higher than that of the coaxial cable 2 is maintained. Can be expressed. Moreover, since the end of the coaxial cable strand 1 can be processed into a uniform shape, the multi-core coaxial cable 4 can be reliably and easily connected to the connection point of the substrate or the connector. Therefore, it is possible to reduce the number of work steps required for the connection process of the multicore coaxial cable 4.

  Further, the coaxial cable strand 1, coaxial cables 2, 3 and multi-core coaxial cable 4 according to the present invention described above are, for example, a cable for connecting a diagnostic probe and a signal processing apparatus in an ultrasonic diagnostic apparatus, an endoscope On the cable connecting the imaging unit and the signal processing unit, or on a bent part such as an arm joint of an industrial robot, such as a cable of another medical device in which the sensor or probe and the signal processing unit are connected by a cable The cable used to connect the display unit such as a display in a notebook computer and the main body unit in which the memory, the calculation unit and the storage unit are arranged, and is also subjected to mechanical vibrations of a vibration device, a power unit, etc. Connected to a part exposed to fluid vibration, such as a cable connected to the part, an instrumentation sensor or probe installed in the fluid piping It can be suitably used for such Buru.

  Note that the surfaces of the center conductor 11 and the outer conductor 13 may be plated with a metal such as tin or silver and solder. Further, the outer jacket 41 constituting the multi-core coaxial cable 4 may be formed by only the outer jacket 41b. Furthermore, the insulator 12 may be formed by applying an insulating organic and / or inorganic material, or coating it by thermal spraying or vapor deposition.

  Specific examples according to the present invention will be described below, but the present invention is not limited thereto.

<Example 1>
(1) Production of coaxial cable strand: First, a metal material having a silver content of 5% by weight and the balance being copper and inevitable impurities was cast to obtain an ingot. Next, after cold rolling the ingot, heat treatment and wire drawing are performed to produce a strand having an outer diameter of 0.08 mm, and the surface of the strand is plated with tin to obtain a central conductor. It was. Next, an insulator made of polyethylene terephthalate is extruded around the center conductor so that the outer diameter becomes 0.23 mm, and further, an outer diameter of 0.03 mm made of a copper alloy having a tensile strength of 55 kg / mm ² . A tin-plated copper alloy wire was subjected to a horizontal winding shield treatment to form an outer conductor to obtain a coaxial cable strand. Table 1 shows the measurement results of the tensile strength and plastic elongation of the central conductor and the tensile strength of the outer conductor.
(2) Preparation of coaxial cable: The coaxial cable strand is sandwiched between strips of polyvinyl chloride (hereinafter referred to as “PVC”), and the strip is heated and welded to the entire surface of the coaxial cable by a heating device. A single-core coaxial cable having an outer diameter of 0.33 mm was obtained.
(3) Production of multi-core coaxial cable: The above-mentioned 192 coaxial cables were bundled so that the central axes of the coaxial cables coincided with each other so that the outer shape was circular, thereby obtaining an assembly of coaxial cables. A multi-core coaxial cable is obtained as a coaxial cable bundle having an outer diameter of 8.2 mm by braiding a small-diameter tin-plated conductor on the outer periphery of the assembly, and further applying a PVC outer jacket on the outer periphery. It was.

<Example 2>
A tin-plated copper alloy wire made of a copper alloy having a silver content of 3% by weight for the central conductor, the balance being copper and inevitable impurities, and a tensile strength of 80 kg / mm ² for the outer conductor A multi-core coaxial cable was obtained in the same manner as in Example 1 except that was used. Table 1 shows the measurement results of the tensile strength and plastic elongation of the center conductor and the tensile strength of the outer conductor.

<Comparative example 1>
The above embodiment except that the central conductor is a stranded wire having an outer diameter of 0.09 mm formed by twisting a tin-plated copper alloy wire having an outer diameter of 0.03 mm made of a copper alloy having a tensile strength of 80 kg / mm ^2. In the same manner as in Example 1, a multicore coaxial cable was obtained. Table 1 shows the measurement results of the tensile strength and plastic elongation of the center conductor and the tensile strength of the outer conductor.

<Comparative example 2>
Except that a single wire of a tin-plated copper wire having an outer diameter of 0.08 mm obtained by processing an electrical roughing copper wire defined in JIS C 3106 was used as the central conductor, the same as in Example 1 above. A multi-core coaxial cable was obtained. Table 1 shows the measurement results of the tensile strength and plastic elongation of the center conductor and the tensile strength of the outer conductor.

<Comparative Example 3>
Except having used the single wire of the tin-plated copper wire of outer diameter 0.08mm obtained by processing the rough wire for electrical use specified in JIS C3106 as a central conductor, it carried out similarly to the said Example 2 above. A multi-core coaxial cable was obtained. Table 1 shows the measurement results of the tensile strength and plastic elongation of the center conductor and the tensile strength of the outer conductor.

<Bending test 1>
The center conductor used in Examples 1 and 2 and Comparative Examples 1 to 3 was used as a test body, and a bending test was performed according to the method shown in the bending test method 1 described above. As a result, the central conductor used in the present invention used in the examples withstands the number of bendings three to four times that of Comparative Example 1 and 10 times or more that of Comparative Examples 2 and 3, and has a high bending life. It has been confirmed that it has bending resistance. Therefore, the coaxial cable strand, the coaxial cable, and the coaxial cable bundle of the present invention use a center conductor having excellent bending resistance as the center conductor, which is compared with the conventional one using a twisted wire as the center conductor. Thus, it is understood that it has excellent bending resistance.

<Bending test 2>
Each multi-core coaxial cable produced in Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3 was subjected to a bending test according to the method shown in the bending test method 2 described above. The results are summarized in Table 1. As a result, the multicore coaxial cables of Examples 1 and 2 did not break the center conductor even when bent more than 600,000 times and 300,000 times, respectively. It was confirmed that it has sufficient bending resistance equal to or better than that of the core coaxial cable. On the other hand, the multi-core coaxial cables of Comparative Examples 2 and 3 in which the central conductor is a single wire are broken by 12000 times of bending, and the bending resistance of the multi-core coaxial cables of Examples 1 and 2 is Comparative Example 2 and It was confirmed that it was 20 times or more than the number 3 multi-core coaxial cable. From these facts, it is understood that the coaxial cable bundle according to the present invention has sufficient bending resistance even though a single wire is used as the central conductor.

<Terminal compression test>
The terminal of each coaxial cable strand produced in Example 1 and Comparative Example 1 was sandwiched between molds, and the terminal was compressed and deformed by applying a load from two directions. Before and after such compression deformation, the cross-sectional shape of the central conductor constituting each coaxial cable was observed with a microscope. As a result, before compressive deformation, the cross sections of all the central conductors were substantially perfect circles. Further, after the compressive deformation, the cross section of the central conductor used in Example 1 had a flat elliptical shape, and the shape was reproducible. On the other hand, the central conductor made of the stranded wire used in Comparative Example 1 was scattered with the fine wires constituting the stranded wire, and the cross-sectional shape changed every time the compression deformation occurred. Next, when the coaxial cable strands after compression deformation were joined to the substrate by soldering, the coaxial cable strand of Example 1 in which the cross-sectional shape of the central conductor was deformed into a uniform elliptical shape was an elliptical flat surface. As a contact, it was well connected to the substrate. On the other hand, the coaxial cable strand of Comparative Example 1 is difficult to connect due to the influence of the scattered fine wires, and preliminary soldering is applied to the tip of the coaxial cable strand to fix the thin wires together. It was necessary to apply. From this, it is understood that the coaxial cable strand of the present invention is extremely excellent in the workability of the terminal, and therefore, the connection to the substrate or the like is extremely simple.

It is a perspective view showing one embodiment concerning a coaxial cable of the present invention. It is sectional drawing which shows one Embodiment which concerns on the coaxial cable of this invention. It is sectional drawing which shows other embodiment which concerns on the coaxial cable of this invention. It is sectional drawing which shows one Embodiment which concerns on the coaxial cable bundle of this invention. It is a schematic diagram for demonstrating the bending test method in this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Coaxial cable strand, 2, 3 ... Coaxial cable, 4 ... Multi-core coaxial cable (coaxial cable bundle), 11 ... Center conductor, 12 ... Insulator, 13 ... External conductor, 21, 31 ... Outer skin (outer skin member) 41 ... Outer jacket (outer member).

Claims (8)

A coaxial cable comprising a center conductor, an insulator covering the periphery of the center conductor, and an outer conductor covering the periphery of the insulator,
The center conductor is formed of a single wire made of a metal material containing copper and silver, has a tensile strength of 120 kgf / mm ² or more, and an electrical conductivity of 60 to 90% IACS. A featured coaxial cable strand. The coaxial cable strand according to claim 1, wherein the plastic elongation of the center conductor satisfies a relationship represented by the following formula (1).
0.2% ≦ L ≦ 2.0% (1)
[Wherein L represents plastic elongation (%). ]   The coaxial cable strand according to claim 1 or 2, wherein a silver content in the metal material is 2 to 10% by weight. The coaxial cable element according to any one of claims 1 to 3, wherein the tensile strength of the central conductor and the tensile strength of the outer conductor satisfy a relationship represented by the following formula (2). line.
Tg ≦ Tc ≦ Tg × 3 (2)
[In the formula, Tc represents the tensile strength of the central conductor, and Tg represents the tensile strength of the outer conductor. ]   5. The coaxial cable strand according to claim 1, wherein an outer diameter of the center conductor is 0.010 to 0.2 mm.   A coaxial cable comprising: the coaxial cable strand according to any one of claims 1 to 5; and a sheath member covering a periphery of the coaxial cable strand.   The coaxial cable according to claim 6, wherein a plurality of the coaxial cable strands are provided, and the coaxial cable strands are arranged in parallel inside the outer skin member.   A coaxial cable bundle comprising a plurality of the coaxial cables according to claim 6 or 7, wherein each of the coaxial cables is disposed inside a jacket member.

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