JP2012064543A - Coaxial cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coaxial cable having a central conductor composed of a single wire and excellent fatigue characteristics, and to provide a coaxial cable bundle.SOLUTION: A coaxial cable 1 is a short material with length of 1000 mm or less, and a central conductor 10 is a single wire conductor mainly composed of one Cu-Ag alloy wire 11. The Cu-Ag alloy wire 11: consists of Cu-Ag alloys containing Ag of 5 mass % or more and 15 mass % or less; has a diameter of 15 μm or more and 50 μm or less; and includes a plating layer 12 on the outer periphery. The central conductor 10 satisfies conductivity of 50% IACS or more and tensile strength of 1330 MPa or more. The coaxial cable 1 is protected from disconnection by bending or twisting, and has excellent fatigue characteristics, by comprising the Cu-Ag alloy wire 11 containing Ag in a specified range and having a specified size, and the central conductor 10 satisfying conductivity and tensile strength in the specified range.

Description

  The present invention relates to a coaxial cable having a central conductor made of a Cu-Ag alloy wire, and a coaxial cable bundle in which a plurality of coaxial cables are bundled. In particular, the present invention relates to a coaxial cable in which the central conductor is a single wire conductor and has excellent fatigue characteristics.

  Coaxial cables are used for wiring of various electric / electronic devices such as portable devices such as mobile phones and portable computers, medical devices such as diagnostic probes and endoscopes of ultrasonic diagnostic apparatuses, and industrial robots. Since the wiring is often bent or twisted in use, it is desired that the wiring is not easily broken by bending or twisting, that is, excellent in fatigue characteristics. In order to suppress disconnection due to bending or twisting, use of a twisted wire obtained by twisting a plurality of wire materials can be mentioned. Therefore, conventionally, a stranded conductor is widely used as the central conductor of the coaxial cable. Moreover, what consists of pure copper is used widely for the said wire.

  Recently, along with the miniaturization of the above-mentioned electric / electronic devices, the coaxial cable has also become thinner. Therefore, it is necessary to make the wire constituting the central conductor thin, but it is easy to break in the middle of wire drawing due to its thinness (the wire drawability is bad), it is difficult to twist even if it can be drawn, or when twisting Disconnection (poor twisting). Also, when connecting the central conductor of the coaxial cable to an electronic circuit board or the like, the wire materials twisted together when performing terminal connection processing such as soldering are scattered, and the wiring patterns on the substrate are short-circuited via these wire materials. There is a fear. On the other hand, Patent Document 1 proposes that the central conductor is a single wire conductor made of a Cu—Ag alloy. The Cu-Ag alloy has higher strength than pure copper, and can be made as a single wire conductor, thereby improving the wire drawing property, omitting the stranded wire process, and improving the workability of the terminal connection process.

JP 2008-258172 A

  The coaxial cable described in Patent Document 1 is mainly intended for relatively long cables such as medical equipment and industrial robot wiring. On the other hand, the wiring of relatively small electric / electronic devices such as mobile phones and portable computers is short. Specifically, the length may be even shorter, such as 1 m (1000 mm) or less, 50 cm (500 mm) or less, or 30 cm (300 mm) or less depending on the application. Further, it is desired to develop a coaxial cable having excellent fatigue characteristics for a coaxial cable used for such a relatively short wiring having a length of 1000 mm or less.

  For example, when the same twist is applied to a cable having a short length and a cable having a long length, the short cable has a large proportion of a region subjected to fatigue due to the twist with respect to the entire length, and the degree of fatigue is also large. For this reason, simply shortening a long cable makes it difficult to secure the same or better characteristics than a long cable. In particular, as described above, a single wire conductor is easier to be fatigued than a stranded wire conductor in consideration of wire drawability and productivity, and therefore has characteristics equivalent to or better than a coaxial cable having a stranded wire conductor. The development of a single-conductor coaxial cable is desired.

  Accordingly, one of the objects of the present invention is to provide a coaxial cable having a central conductor that is a single conductor and excellent in fatigue characteristics. Another object of the present invention is to provide a coaxial cable bundle in which a plurality of the coaxial cables are bundled.

  The inventors of the present invention select Ag as an additive element that has a relatively low conductivity and is effective in improving strength, and is intended for Cu-Ag alloy wires and has a relatively short length as described above. A variety of configurations with excellent fatigue characteristics when the center conductor is a single-wire conductor were studied. As a result, by using a Cu-Ag alloy wire satisfying a specific range in the content and size (diameter) of Ag, by configuring the central conductor so that the electrical conductivity and tensile strength satisfy a specific range, It was found that a coaxial cable having excellent fatigue characteristics can be obtained even though it is a relatively short coaxial cable and the central conductor is a single conductor. The present invention is based on the above findings.

  The coaxial cable of the present invention comprises a central conductor, an electrical insulating layer provided on the outer periphery of the central conductor, and an outer conductor provided on the outer periphery of the electrical insulating layer and disposed coaxially with the central conductor. It is a relatively short cable with a length of 1000mm or less. Further, the central conductor of this coaxial cable is a single wire conductor composed of one strand. The element wire includes a Cu-Ag alloy wire composed of a Cu-Ag alloy containing 5 mass% to 15 mass% of Ag and the balance being Cu and impurities, and an outer periphery of the Cu-Ag alloy wire. And an Ag plating layer or Sn plating layer. The diameter of the Cu—Ag alloy wire is 15 μm or more and 50 μm or less, the conductivity of the center conductor is 50% IACS or more, and the tensile strength of the center conductor is 1330 MPa or more.

  In the coaxial cable of the present invention, since the central conductor is a single wire conductor, it is possible to improve the wire drawing property, omit the twisting step, and improve the workability of the terminal connection process as compared with the case where it is a stranded wire conductor. it can. In addition, the coaxial cable of the present invention is mainly composed of a Cu-Ag alloy wire that has a specific composition in which the center conductor has a specific Ag content as described above and satisfies a specific size (diameter). In addition, by satisfying specific ranges of conductivity and tensile strength, it is a relatively short cable of 1 m or less and is a single wire conductor, but has excellent resistance to twisting and bending, and fatigue characteristics. Excellent.

As an embodiment of the present invention, there is an embodiment in which the ratio of the thickness of the electrical insulating layer to the diameter of the central conductor is 65% or more and the attenuation amount of the coaxial cable at 1 GHz is 12 dB / m or less. Moreover, as one form of this invention, the form whose cycle number of the said coaxial cable in the following fatigue tests is 200,000 times or more is mentioned.
[Fatigue test]
A bundle sample in which 30 to 40 coaxial cables are bundled is prepared, each end of the sample is fixed to a jig capable of biaxial rotation, and the following opening / closing and twisting tests are performed. The two axes are arranged so that one axis and the other axis are orthogonal to each other.
Opening / Closing / Torsion Test Using one axis as the rotation axis, the opening angle is rotated from 0 ° to 90 °. Subsequently, with the other axis as a rotation axis, a rotation operation is performed from a rotation angle α of 0 ° to 180 °, and a reverse rotation operation is further performed from a rotation angle α: 180 ° to 0 °. Subsequently, the closing operation is performed from the rotation angle θ of 90 ° to 0 ° with the one axis as a rotation axis. A series of these biaxial rotation operations is defined as one cycle, and is performed at about 11 seconds / cycle.

  According to the said form, since the thickness of an electric insulation layer is thick enough, there is little attenuation amount and it can utilize suitably as a signal transmission path. In addition, according to the above-described embodiment, even a short coaxial cable and a single wire conductor have sufficient fatigue characteristics. -It can be suitably used for wiring of electronic devices, typically mobile phones. The greater the ratio of the thickness of the electrical insulation layer, the less the attenuation, so 75% or more, more preferably 80% or more. However, if the thickness of the electrical insulation layer is too thick, the cable becomes thick, so 100% or less Is preferred. Further, since the smaller the attenuation, the better for the signal transmission path, there is no particular lower limit.

As one aspect of the present invention, the diameter of the center conductor is 90% or less of the diameter of the center conductor of the following comparison cable, and the outer diameter of the electric insulation layer is equal to the outer diameter of the electric insulation layer of the comparison cable. A form in which the attenuation amount of the coaxial cable at 1 GHz is equal to or less than the attenuation amount of the comparison cable can be mentioned. Moreover, as one form of this invention, the form whose cycle number of the said coaxial cable in the following fatigue tests is more than equivalent to the cycle number of the said comparison cable is mentioned.
[Comparison cable]
The central conductor is a stranded conductor made by twisting seven strands of strands composed of a Cu-Ag alloy containing 0.6% by mass of Ag and the balance being Cu and impurities. Has a diameter of 16 μm (diameter of stranded conductor: 48 μm). In addition, the electrical insulation layer of the comparison cable is made of the same material as that constituting the electrical insulation layer of the coaxial cable.
[Fatigue test]
A bundle sample in which 30 to 40 coaxial cables are bundled and a bundle comparison sample in which the same number of comparison cables are bundled with the coaxial cable are produced, and each end of each sample can be rotated biaxially. And open / close and twist tests as described above.

  The coaxial cable of the said form has a thin center conductor compared with the comparison cable which imitated the general purpose coaxial cable whose center conductor is a stranded conductor. And since the outer diameter of the electrical insulation layer (the total diameter of the center conductor and the electrical insulation layer) is equal between the coaxial cable of the above form and the comparison cable, the thickness of the electrical insulation layer of the coaxial cable of the above form is relatively Thick. In this way, since the electrical insulation layer is sufficiently thick, the amount of attenuation is small. Therefore, according to the above embodiment, it can be suitably used for a signal transmission line. Moreover, according to the said form, even if it is a short coaxial cable and is a single wire conductor, it has the fatigue characteristic equivalent to or more than the comparison cable which provides a twisted wire conductor. Therefore, the coaxial cable of the above-described form can be suitably used for wiring of various electric / electronic devices having a biaxial rotation mechanism, particularly a small device such as a mobile phone.

  The coaxial cable of the present invention can be used as it is, but can be used in a bundled form (coaxial cable bundle of the present invention). Coaxial cable bundles are very easy to handle because they are bundled together.

  The coaxial cable and coaxial cable bundle of the present invention are excellent in fatigue characteristics.

FIG. 1 is a cross-sectional view of the coaxial cable of the present invention. FIG. 2 is a schematic explanatory view illustrating the configuration of a biaxially rotatable jig used for a fatigue test and a fixed state of a coaxial cable, FIG. 2 (A) is a front view, and FIG. 2 (B) is a side view. FIG. FIG. 3 is a schematic explanatory view illustrating the procedure of a fatigue test. FIG. 4 is an attenuation characteristic graph showing the relationship between frequency and attenuation in a Cu—Ag alloy wire.

Hereinafter, the present invention will be described in more detail.
〔coaxial cable〕
≪Overall structure≫
As shown in FIG. 1, the coaxial cable 1 of the present invention includes a center conductor 10, an outer conductor 14 arranged coaxially with the center conductor 10, and an electric insulation layer 13 that insulates between the two conductors 10 and 14. Further, a configuration including an exterior 15 covering the outer periphery of the outer conductor 14 is representative. The center conductor 10 includes a Cu—Ag alloy wire 11 and a plating layer 12 provided on the surface of the Cu—Ag alloy wire 11. The coaxial cable of the present invention has structural features that the center conductor is a single wire conductor as described later, the diameter of the strands constituting the single wire conductor satisfies a specific range, and the length is relatively short. Can be mentioned. Moreover, as a more preferable form, it is mentioned that the thickness of an electrical insulating layer satisfy | fills a specific range so that it may mention later.

≪Length≫
The coaxial cable of the present invention has a length of 1000 mm or less. Depending on the application, forms such as 500 mm or less and 300 mm or less can be mentioned. This length can be appropriately selected according to the application. When a long coaxial cable is manufactured and cut to a desired length, the coaxial cable of the present invention can be manufactured with high productivity.

≪Center conductor≫
[composition]
The main wire constituting the central conductor is a Cu—Ag alloy wire made of a binary alloy (Cu—Ag alloy) containing a specific amount of Ag. When the Ag content is 5% by mass or more, the strength is improved by precipitation strengthening of Ag, and the effect of improving the fatigue characteristics is easily obtained, and the fatigue characteristics tend to be further improved as the amount of Ag increases. However, in the case of more than 15% by mass, excessive precipitation of Ag increases the interfacial resistance between Cu and Ag, so that the conductivity decreases. Therefore, in order to achieve both excellent fatigue characteristics and high electrical conductivity, the content of Ag is set to 5% by mass or more and 15% by mass or less in the present invention.

[Wire diameter]
The Cu-Ag alloy wire is typically a round wire having a circular cross section. In particular, in the present invention, the diameter of the Cu—Ag alloy wire is set to 15 μm (0.015 mm) or more and 50 μm (0.05 mm) or less as a size that can be sufficiently used as a single wire conductor. By setting the thickness to 15 μm or more, it is possible to suppress a decrease in conductivity due to an excessively high degree of workability at the time of wire drawing, and to have a specific size of conductivity, and it is difficult to cause disconnection at the time of wire drawing. Excellent linearity and excellent wire productivity. In addition, when the thickness is 50 μm or less, the cable diameter does not become too large, and a thin cable can be obtained. More preferably, it is 45 μm (0.045 mm) or less, and more preferably 40 μm (0.04 mm) or less. The diameter of the central conductor including the Cu-Ag alloy wire and the plating layer described later is also preferably 50 μm or less, particularly 45 μm or less, and more preferably 40 μm or less. Further, the diameter of the center conductor is 90% or less of the diameter of the center conductor of the comparative cable imitating the above-described general-purpose coaxial cable, which is thinner than the general-purpose coaxial cable, and the effect of reducing the diameter can be obtained. However, if it is too thin as described above, the conductivity and the productivity are lowered, and therefore the diameter of the center conductor is preferably 30% or more of the diameter of the center conductor of the comparison cable. The diameter of the Cu-Ag alloy wire can be changed by appropriately changing the degree of processing at the time of wire drawing, and the diameter of the central conductor comprising this Cu-Ag alloy wire is the same as the diameter of the Cu-Ag alloy wire. The thickness can be changed by appropriately changing the thickness of the plating layer described later.

[Characteristic]
Here, in the Cu-Ag alloy, the tensile strength and the electrical conductivity are generally in a trade-off relationship, and the Ag content and the tensile strength are in a generally proportional relationship. From these relationships, the present inventors have found a range having sufficient fatigue characteristics when the central conductor is a single wire conductor, and the present invention defines the range. Specifically, the conductivity of the central conductor including the Cu-Ag alloy wire is 50% IACS or more and the tensile strength is 1330 MPa or more. The conductivity and tensile strength are preferably as high as the above lower limit values are satisfied. The conductivity is preferably 55% IACS or more, more preferably 60% IACS or more, and the tensile strength is preferably 1400 MPa or more, more preferably 1500 MPa or more. Tensile strength tends to increase by increasing the Ag content, increasing the degree of processing during wire drawing, or adjusting the presence of Ag precipitates by heat treatment. , The content of Ag tends to be increased by reducing the Ag content or sufficiently precipitating the Ag precipitate by heat treatment. It is preferable to adjust the Ag content and production conditions so as to obtain desired characteristics.

[Plating layer]
When connecting a coaxial cable to a circuit board or the like, solder is generally used. By providing a plating layer on the outer periphery of the Cu-Ag alloy wire, the wettability with solder can be improved and the corrosion resistance of the Cu-Ag alloy wire can be improved. The material of the plating layer is preferably Ag or Sn. Although the thickness of the plating layer can be selected as appropriate, the wettability with the solder can be sufficiently enhanced even with a thickness of 1 μm or less, particularly 0.3 μm or less, and the center conductor is not excessively large and has a small diameter. A center conductor is preferable. The thickness of the plating layer is easily 0.8 μm to 0.2 μm.

≪Electrical insulation layer≫
As the constituent material of the electrical insulating layer formed on the outer periphery of the central conductor, an appropriate material excellent in electrical insulation and flexibility, typically an insulating resin, can be suitably used. Specifically, epoxy resins, polyester resins, polyurethane resins, polyvinyl alcohol resins, vinyl chloride resins, vinyl ester resins, acrylic resins, epoxy acrylate resins, diallyl phthalate resins, phenol resins, Polyamide resin, polyimide resin, and melamine resin are listed. In particular, a fluororesin such as tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) is suitable.

  The electrical insulating layer tends to reduce the attenuation as the thickness thereof increases. In order to obtain this effect, the thickness of the electrical insulating layer is preferably 65% or more, more preferably 75% or more, with respect to the diameter of the central conductor. Further, the diameter of the central conductor of the coaxial cable is 90% or less of the diameter of the central conductor of the comparison cable, and the outer diameter of the electric insulation layer of the coaxial cable is equal to the outer diameter of the electric insulation layer of the comparison cable. In the same form, the thinner the central conductor of the coaxial cable, the thicker the electrical insulation layer is than the comparative cable. Therefore, in this embodiment, the attenuation can be reduced as the diameter of the central conductor is reduced. As described above, even when the Cu-Ag alloy wire has a smaller diameter of 40 μm or less, the attenuation can be reduced by forming the electrical insulating layer relatively thick. Note that when the electrical insulating layer is made of a material having a low dielectric constant (for example, 50 pF / m or less), it is expected that the attenuation can be reduced even if the thickness is somewhat thin.

≪Other composition≫
As the outer conductor and the exterior, a known thin coaxial cable configuration can be used as appropriate. The outer conductor is a part that functions as a shield layer, and a wire made of Cu or a Cu—Ag alloy can be suitably used as a constituent material thereof. Examples include a form in which a tape-shaped wire or a round wire is laterally wound around the outer periphery of the electrical insulating layer (a spirally wound form), a form in which a braided material knitting the wire is disposed on the outer periphery of the electrical insulating layer, etc. It is done. As the constituent material of the exterior, a resin excellent in electrical insulation and flexibility described in the electrical insulation layer, in particular, a thermoplastic resin can be suitably used.

(Coaxial cable bundle)
The coaxial cable bundle of the present invention includes a plurality of coaxial cables of the present invention and a bundling member that integrates these cables. The integrated state by the bundling member is, for example, a form in which a plurality of coaxial cables are arranged in parallel and wound with an adhesive tape, and a form in which a plurality of coaxial cables are arranged in parallel and extruded with resin or the like on its outer periphery Etc. In addition, as one form of the coaxial cable bundle, a form in which connection members such as connectors are attached to both ends can be cited. According to this embodiment, since a plurality of coaxial cables can be attached to an electric / electronic device at a time, the connection workability is excellent. A typical form includes a form in which one connector is provided for a coaxial cable group integrated by a bundling member. In a form that does not include a connecting member such as the connector, solder is applied directly to the end of the coaxial cable group and connected to a substrate or the like. Known materials can be used as appropriate for the material, forming method, attaching method, and the like of the connecting member and the binding member.

[Use]
The coaxial cable and the coaxial cable bundle of the present invention have a relatively short length of 1000 mm or less. Therefore, the wiring of a small electric / electronic device, typically a portable device such as a mobile phone or a portable computer, particularly a biaxial It can be suitably used for the wiring of equipment having a rotating mechanism. In addition, when the length exceeds 1000 mm, it can also be used for wiring of medical equipment and industrial robots.

[Characteristics of coaxial cable]
The coaxial cable having the above configuration has a cycle number of 200,000 times or more when the above-described fatigue test is performed, or a cycle number equal to or greater than that of the comparative cable, and has excellent fatigue characteristics. Further, the coaxial cable having the specific thickness of the electrical insulating layer has an attenuation amount of 1 dB / m or less at 1 GHz or equal to or less than that of the comparative cable, and is not easily attenuated. Therefore, the coaxial cable and coaxial cable bundle of the present invention can be suitably used for a signal transmission path.

〔Production method〕
The coaxial cable of the present invention can be typically manufactured by a manufacturing process in which a central conductor is formed, an electrical insulating layer is formed, an external conductor is formed, and an exterior is formed. In particular, the basic manufacturing process of the center conductor includes the production of cast material ⇒ wire drawing. An intermediate heat treatment may be performed during the wire drawing. The timing for performing the intermediate heat treatment can be selected as appropriate, and the intermediate heat treatment may not be performed.

  The inventors of the present invention have obtained the following knowledge in manufacturing a Cu-Ag alloy wire having a specific content, specific conductivity, and tensile strength in which the Ag content is in the specific range described above. . When the Ag content is relatively low in the range of 5% to 15% by mass (5% to 10% by mass or less), the conductivity is 50% even without intermediate heat treatment in the middle of wire drawing. Cu-Ag alloy wire with IACS or higher and tensile strength of 1330 MPa or higher is obtained. When the amount is relatively high (about 10% by mass or more), intermediate heat treatment is performed during wire drawing, especially with high Ag content. It was found that it is preferable to delay the time for performing the intermediate heat treatment (intermediate heat treatment is performed after the wire diameter is reduced). In the present invention, the range of the Ag content is specified to some extent, but by establishing the manufacturing process based on the Ag content as described above, the specific Cu-Ag alloy wire can be produced with high productivity. It can be manufactured and has high industrial significance.

  In producing a cast material, raw materials are prepared so as to have a predetermined composition. When the raw material Cu or the raw material Ag has a high purity, for example, one having four nines (purity 99.99%) or more is used, there are few impurities, and foreign matter that can be involved in disconnection can be reduced when manufacturing a thin wire.

  The cast material may be subjected to heat treatment such as solution treatment or homogenization treatment before wire drawing. The conditions for the solution treatment include heating temperature: 600 ° C. or more and 850 ° C. or less, holding time: 0.5 hour or more, and cooling rate: 1.5 ° C./sec or more. By performing solution treatment under these conditions, Ag can be sufficiently dissolved in Cu. As the holding time is longer, Ag tends to be sufficiently dissolved in Cu, and it is preferable to select appropriately within a range not causing a decrease in productivity. As the cooling rate is higher, the precipitation of Ag can be suppressed, and it is preferable to perform rapid cooling at 1.5 ° C./sec or more, and further 3 ° C./sec or more. For such rapid cooling, use forced cooling means as appropriate, such as direct cooling using a fluid refrigerant such as water, oil, sand, blast using a fan, etc., or using a water-cooled copper block. Can be realized. In the case of performing the solution treatment, the strength (fatigue property) can be improved by precipitation strengthening by precipitating Ag that has been subjected to intermediate heat treatment in the middle of wire drawing to cause solid solution. The conditions for the homogenization treatment include heating temperature: 500 ° C. or more, holding time: 0.5 hour or more, and cooling rate: 50 ° C./sec or less.

  The wire drawing (typically cold) is performed over a plurality of passes until the final wire diameter is reached. The degree of processing of each pass may be appropriately adjusted in consideration of the composition (Ag content), the final wire diameter, and the like. A part of the precipitated Ag is drawn into a fibrous shape by the wire drawing process, and it is considered that an effect of improving the strength (fatigue property) can be obtained by strengthening with the fibrous Ag.

  The intermediate heat treatment performed in the middle of wire drawing mainly aims at the effect of improving the strength by precipitation strengthening of Ag. It is considered that a part of the precipitated Ag by this heat treatment is in the form of very fine particles such as nano-order. Cu-Ag alloy wire with high electrical conductivity and strength can be produced by the presence of the above-mentioned fibrous Ag, the presence of the above-mentioned ultrafine Ag uniformly dispersed, or the coexistence of both. it is conceivable that.

  The intermediate heat treatment may be performed a plurality of times, but if it is performed once, the number of manufacturing steps is small and the productivity is excellent. When applied multiple times, Ag is sufficiently precipitated to increase strength and electrical conductivity, to improve the electrical conductivity by removing processing strain introduced by wire drawing, or to make wire drawing after heat treatment easier. It is expected that you can.

  The conditions for the intermediate heat treatment include heating temperature: 300 ° C. or higher and holding time: 0.5 hour or longer. By setting the heating temperature to 300 ° C. or more and the holding time to 0.5 hours or more, Ag can be sufficiently precipitated or processing strain can be sufficiently removed. The higher the heating temperature and the longer the holding time, the easier it is to precipitate Ag. Moreover, the fall of the electroconductivity by Ag solid-dissolving in Cu again can be suppressed by making heating temperature 600 degrees C or less. Therefore, the heating temperature is preferably 600 ° C. or less, particularly 350 ° C. or more and 550 ° C. or less, more preferably 400 ° C. or more and 450 ° C. or less, and the holding time is preferably 0.5 hours or more and 10 hours or less. The cooling method during the intermediate heat treatment includes, for example, furnace cooling in which it is left in a heat treatment furnace and cooled by natural cooling.

  A plating layer is formed during the wire drawing process or on the wire having the final wire diameter. The plating method typically includes electroplating, but electroless plating may be used.

  A known method can be used as appropriate for the formation of the outer conductor and the exterior and the formation of the coaxial cable bundle.

[Test example]
Manufacture Cu-Ag alloy wire under various conditions, manufacture coaxial cable using this Cu-Ag alloy wire as the central conductor, and for each coaxial cable obtained, mechanical characteristics, fatigue characteristics, damping characteristics, The state at the time of terminal processing was examined.

  The Cu-Ag alloy wire was produced as follows. Prepare copper as the raw material Cu with a purity of 99.99% or more, and silver grains (Ag) with a purity of 99.99% or more as the raw material Ag, put them in a high-purity carbon crucible, and vacuum-melt them in a continuous casting machine. Cu and Ag A mixed molten metal was dissolved. As shown in Table 1, the amount of silver grains added is 0.6 mass% (sample No. 100), 5 mass% to 15 mass% (sample No. 1 to 5) with respect to the mixed molten metal. It adjusted so that it might become.

  Using the obtained molten metal, a cast material having a circular cross section having a casting size (any one of φ22 mm, φ16 mm, and φ8.0 mm) shown in Table 1 was manufactured by continuous casting with a high-purity carbon mold.

  The obtained cast material was subjected to cold drawing to obtain strands having the wire diameters (final wire diameters) shown in Table 1 (sample No. 100 was a strand for strands). Samples Nos. 2 to 5 were subjected to intermediate heat treatment under the conditions shown in Table 1 when the wire diameters (sizes) shown in Table 1 were in the middle of the wire drawing. In addition, in each sample, when the wire diameter was φ0.36 mm in the middle of wire drawing, a plating layer having the material shown in Table 1 was formed by electroplating, and subsequently wire drawing was performed. Therefore, all the obtained strands have a plating layer on the outer periphery of the Cu-Ag alloy wire. Here, in any sample, the thickness of the plating layer is 0.3 μm or less.

  Sample Nos. 1 to 5 were never disconnected until 2 kg of the strand having the final wire diameter was produced, but sample No. 100 was disconnected 13 times as shown in Table 1.

  The tensile strength (MPa) and electrical conductivity (% IACS) of the wire comprising the obtained plating layer were measured. The results are shown in Table 1. The tensile strength was measured in accordance with the provisions of JIS Z 2241 (1998) (marking distance GL: 250 mm). The conductivity was measured by the bridge method. When measuring the tensile strength and conductivity of the center conductor for a coaxial cable with a center conductor, electrical insulation layer, outer conductor, and sheath, disassembling the coaxial cable and taking out the center conductor as appropriate Good.

  Using the wire with the plating layer of sample No. 1 to 5 as the central conductor and using the material shown in Table 1 on the outer periphery of this central conductor, the electrical insulation layer is formed by extrusion to the thickness shown in Table 1. Furthermore, an outer conductor and an exterior were formed in that order on the outer periphery to produce a coaxial cable. For the outer conductor and the exterior, a known material was used, and the same material was used for any sample. Sample No. 100 was prepared by twisting and twisting 7 strands for stranded wire with a diameter of φ16μm, and using the same materials as Sample No. 1 to 5, using the same material as the insulation layer, external conductor, and exterior A coaxial cable (hereinafter referred to as a comparative cable) was produced. The electrical insulation layers of the coaxial cables of Sample Nos. 1 to 5 have a uniform thickness over the entire circumference of the center conductor. On the other hand, in the comparative cable of sample No. 100, since the outer shape of the center conductor is uneven, the electrical insulating layer has a nonuniform thickness over the entire circumference of the center conductor. Therefore, in the comparative cable of sample No. 100, Table 1 shows the thickness of the portion where the thickness of the electric insulating layer is the thinnest (the portion covering the crown portion of the stranded wire). Note that the electrical insulating layers of Samples Nos. 1 to 5 and 100 are all made of the same material, and thus have the same dielectric constant. The diameter (wire diameter) of the central conductor of the coaxial cable and the thickness of the electrical insulating layer can be easily measured by observing the cross section under a microscope.

  For each of the obtained coaxial cables of sample Nos. 1 to 5 and the comparative cable of sample No. 100, using a commercially available device (here, Network Analyzer Agilent Technologies, Inc. HP8753ES), the attenuation (dB / m) was measured. Table 1 shows the attenuation when the frequency is 1 GHz. In addition, FIG. 4 shows attenuation amounts at various frequencies in sample Nos. 2, 3, and 100. Here, in measuring the attenuation, the cable length of each sample is set to 1 m so that the calculation is easy, but it may be shortened.

  A fatigue test simulating a mobile phone having a biaxial rotation mechanism was performed on the obtained coaxial cables of Sample Nos. 1 to 5 and the comparative cable of Sample No. 100, and the number of cycles was measured. This fatigue test was performed by preparing the following bundle samples and bundle comparison samples, and fixing each bundle sample and bundle comparison sample to a jig described later.

  Prepare 40 coaxial cables of sample Nos. 1 to 5 and a comparative cable of sample No. 100 (both length: approx. 200 mm). A bundle sample (sample Nos. 1 to 5) and a bundle comparison sample (sample No. 100) were produced by winding and bundling (registered trademark of Sumitomo Electric Industries, Ltd.) tape).

  Next, the jig used in the fatigue test will be described with reference to FIG. The jig 100 has a mechanism capable of biaxial rotation, and is movable with respect to the support leg 101, the movable plate 102 pivotally supported with respect to the support leg 101, and the support leg 101. A first rotating shaft 103 and a second rotating shaft 105 that support the plate 102 rotatably are provided. The second rotation shaft 105 is disposed so that the respective axis directions are orthogonal to the first rotation shaft 103, and the movable plate 102 is rotatably mounted on the support frame 104. Here, the movable plate 102 is pivotally supported by the first rotation shaft 103 so as to be able to rotate at a rotation angle θ: 0 ° to 180 ° about the first rotation shaft 103. This rotation operation is an operation of drawing an arc from left to upper to right in FIG. 2 (B), and is performed by the shaft portion 110 (a first rotation axis and a second rotation axis are schematically shown) shown in FIG. This is an operation simulating a state in which the pair of plate-like portions 111 and 112 supported to be opened and closed performs an opening and closing operation with the shaft portion 110 (first rotation shaft) as an axis. Further, in the state where the movable plate 102 is rotated at the rotation angle θ: 90 ° about the first rotation shaft 103 (the state shown in FIGS. 2 (B) and 3 (B)), the movable plate 102 is further The rotary shaft 105 is pivotally supported by the second rotary shaft 105 so as to be able to rotate at a rotation angle α of 0 ° to 180 °. This rotating motion is a motion of drawing an arc from left to front to right in FIG. 2 (B), and as shown in FIGS. 3 (B) to 3 (D), one plate-like portion 112 is supported by the support leg. 101, the shaft portion 110 (first rotation axis) is used as an axis, and the rotation angle θ: 0 ° to 90 ° is opened to make the other plate-like portion 111 orthogonal to the plate-like portion 112. , With the shaft portion 110 (second rotation axis) as an axis, the plate-like portion 111 is rotated at a rotation angle α of 0 ° to 180 °, or the rotation angle α is rotated at a rotation angle of 180 ° to 0 °. It imitates the state. Here, the inner diameters of the hinge cylinders constituting the first rotating shaft 103 and the second rotating shaft 105 are both 2 mm, and the thickness of the movable plate 102 is 1 mm.

One end of the produced bundle sample 20 or bundle comparison sample is fixed to the support leg 101 as shown in FIG. 2 (A), and the other end is fixed to the surface of the movable plate. When being introduced into the hinge cylinder (support frame 104) constituting the first rotation shaft 103 or into the hinge cylinder, the bundle sample 20 and the bundle comparison sample are appropriately bent. Here, as shown in FIG. 2 (A), the bending radius R ₁ = 5 mm, the bending radius R ₂ = 3 mm, the center of the first rotating shaft 103 from the fixed position of one end of the bundle sample 20 or the bundle comparison sample (FIG. 2 ( The distance L1 from the center of the first rotating shaft 103 to the surface of the movable plate 102 is 5 mm, and the second distance from the fixed position at one end of the bundle sample 20 or the bundle comparison sample The distance L3 to the center of the rotating shaft 105 is 10 mm.

  The following opening / closing / twisting test simulating the opening / closing operation of the mobile phone and the rotation operation of the screen of the mobile phone is performed by fixing the bundle sample 20 and the bundle comparison sample to the jig 100, respectively. Specifically, as shown in FIG. 3 (A), a state in which the pair of plate-like portions 111 and 112 are closed is set as a start state, and as shown in FIG. 3 (B), the shaft portion 110 (first rotating shaft) is moved. An opening operation is performed to rotate the plate-like portion 111 from the rotation angle θ: 0 ° to 90 ° using the rotation axis as a rotation axis, and then the plate-like portion 111 is set to the rotation angle α: By rotating from 0 ° to 180 °, the front surface f and the back surface b of the plate-like portion 111 are opposite to each other as shown in FIG. Subsequently, the plate-like portion 111 is reversely rotated from a rotation angle α: 180 ° to 0 °, and the back surface b and the front surface f are rotated as shown in FIG. 3D (the same direction as that in FIG. 3B). 3), the plate portion 111 is rotated from the rotation angle θ: 90 ° to 0 ° around the shaft portion 110 (first rotation shaft) as shown in FIG. The pair of plate-like portions 111 and 112 are returned to the closed state. A series of these biaxial rotation operations is defined as one cycle of the fatigue test, and is performed at about 11 seconds / cycle, and the number of times until disconnection occurs in at least one of 40 cables in each sample is measured.

  The sample No. 1 and 3 bundle sample and the sample No. 100 bundle comparison sample were subjected to a process simulating an actual terminal connection process, and the deformation processability and the connectivity to the substrate were examined. The results are shown in Table 1. Deformability is achieved by sandwiching the end of each bundle sample and the end of the bundle comparison sample in a mold, and applying loads from two different directions, that is, compressing and deforming the ends by applying two loads. Before and after, the cross-sectional shape of the central conductor included in each sample is evaluated by observing with a microscope. Before applying the load twice in total (before compressive deformation), the central conductor of each sample (element No. 100, which forms a stranded wire) had a substantially circular cross section. The connectivity to the substrate was examined after solder compression on the substrate after the compression deformation.

  As shown in Table 1, a Cu-Ag alloy wire with a diameter of 15 μm to 50 μm is used as the central conductor in the Ag content range of 5% to 15% by mass, and the conductivity of the central conductor is 50%. Sample Nos. 1 to 3 and 5 with IACS or more and tensile strength of 1330 MPa or more have excellent fatigue characteristics even if the center conductor is a single wire and the number of cycles in the fatigue test is 200,000 or more. I understand. In addition, it can be seen that Samples Nos. 1 to 3 and 5 have better fatigue characteristics than the comparative cable of Sample No. 100 having a stranded conductor and Sample No. 4 with less Ag.

  Furthermore, it can be seen that when the thickness of the electrical insulating layer is 65% or more with respect to the diameter (wire diameter) of the central conductor, the attenuation is small and the attenuation characteristics are excellent. In addition, when the wire diameter of the single wire conductor is 90% or less of the wire diameter of the stranded wire conductor and the outer diameter of the electrical insulating layer is the same as that of the comparison cable including the stranded wire conductor, the coaxial cable including the single wire conductor is It turns out that it is excellent in the attenuation | damping characteristic because the thickness of an electrically insulating layer becomes relatively thick. Specifically, the attenuation of these coaxial cables is about the same as or less than that of the comparative cables. Furthermore, as shown in Fig. 4, sample Nos. 2 and 3 are both less attenuated than sample No. 100 up to about 2.5 GHz, the attenuation at 600 MHz is 9 dB / m or less, and the attenuation at 750 MHz is 10 dB. It can be seen that the attenuation characteristics are excellent. In particular, Sample No. 2 has an attenuation of approximately 15 dB / m or less at 2 GHz, and 20 dB / m or less even at 3 GHz.

  Also, as shown in Table 1, in the range where the Ag content is 5% by mass or more and 15% by mass or less, when the Ag is relatively small, even if the intermediate heat treatment is omitted, the conductivity is 50% IACS or more and When a strand with a tensile strength of 1330 MPa or more is obtained and there is a relatively large amount of Ag, the greater the Ag, the smaller the wire diameter that is subjected to intermediate heat treatment during the wire drawing process, resulting in a conductivity of 50%. It can be seen that a wire having an IACS or higher and a tensile strength of 1330 MPa or higher can be obtained.

  In addition, in each of sample Nos. 1 and 3, the section after the above-described compression deformation was deformed into an ellipse, and the shape was reproducible (the variation in the cross-sectional shape for each compression deformation was small). . On the other hand, in sample No. 100, the strands constituting the stranded wire were scattered and the cross-sectional shape was different for each compression deformation. In addition, in each of Sample Nos. 1 and 3, the cross section of the central conductor was deformed into a flat oval shape, so that the flat surface of the ellipse could be satisfactorily connected to the substrate. On the other hand, sample No. 100 is difficult to connect because the strands constituting the stranded wire are scattered, and preliminary soldering is applied to the tip in order to fix them together on the substrate. There was a need. From this result, it can be seen that the coaxial cable having the single conductor as the center conductor is excellent in the processability of the terminal and the connectivity to the substrate.

  From the above test results, Ag is contained in a specific range, a Cu-Ag alloy wire of a specific size is used, and the conductivity and tensile strength are within a specific range, so that the central conductor is a single wire conductor. Even if it exists, it turns out that the coaxial cable and coaxial cable bundle which are excellent in a fatigue characteristic are obtained. In addition, these coaxial cables and coaxial cable bundles have fatigue characteristics equivalent to or better than those of Sample No. 100, where the center conductor is a stranded conductor, but the center conductor can be made thinner, contributing to weight reduction. It is expected to be possible.

  The above-described embodiment can be appropriately changed without departing from the gist of the present invention, and is not limited to the above-described configuration. For example, the length of the coaxial cable, the diameter of the Cu-Ag alloy wire constituting the center conductor, the conductivity / tensile strength of the center conductor, the thickness / material / formation method of the electrical insulation layer, and other manufacturing conditions (during intermediate heat treatment) The heating temperature, the holding time, the timing for performing the intermediate heat treatment, etc.) can be appropriately changed.

  The coaxial cable and the coaxial cable bundle of the present invention can be suitably used for relatively short wiring such as wiring of small electronic / electric equipment such as a mobile phone and a portable computer.

1 Coaxial cable
10 Center conductor 11 Cu-Ag alloy wire 12 Plating layer 13 Electrical insulation layer
14 Outer conductor 15 Exterior
20 Bundle samples
100 Jig 101 Support leg 102 Movable plate 103 First rotating shaft 104 Support frame
105 Second rotation axis
110 Shaft 111,112 Plate-shaped part f Front surface of plate-shaped part 111 b Back surface of plate-shaped part 111

Claims (4)

A coaxial cable comprising a central conductor, an electrical insulating layer provided on the outer periphery of the central conductor, and an outer conductor provided on the outer periphery of the electrical insulating layer and disposed coaxially with the central conductor,
The coaxial cable has a length of 1000 mm or less,
The central conductor is a single wire conductor composed of one strand,
The element wire contains 5 mass% or more and 15 mass% or less of Ag, and a Cu-Ag alloy wire composed of a Cu-Ag alloy with the balance being Cu and impurities,
Ag plating layer provided on the outer periphery of the Cu-Ag alloy wire, or Sn plating layer,
The diameter of the Cu-Ag alloy wire is 15 μm or more and 50 μm or less,
The conductivity of the central conductor is 50% IACS or more,
A coaxial cable, wherein the central conductor has a tensile strength of 1330 MPa or more. The ratio of the thickness of the electrical insulating layer to the diameter of the central conductor is 65% or more,
The attenuation of the coaxial cable at 1 GHz is 12 dB / m or less,
2. The coaxial cable according to claim 1, wherein the number of cycles of the coaxial cable in the fatigue test is 200,000 times or more. The diameter of the center conductor is 90% or less of the diameter of the center conductor of the following comparison cable, and the outer diameter of the electric insulation layer is equal to the outer diameter of the electric insulation layer of the comparison cable,
The attenuation of the coaxial cable at 1 GHz is equal to or less than the attenuation of the comparison cable,
3. The coaxial cable according to claim 1, wherein the number of cycles of the coaxial cable in the fatigue test is equal to or greater than the number of cycles of the comparative cable.
[Comparison cable]
The central conductor is a stranded conductor made by twisting seven strands of strands composed of a Cu-Ag alloy containing 0.6% by mass of Ag and the balance being Cu and impurities. Has a diameter of 16 μm. The electrical insulation layer of the comparison cable is made of the same material as that constituting the electrical insulation layer of the coaxial cable.   A coaxial cable bundle in which a plurality of the coaxial cables according to any one of claims 1 to 3 are bundled.

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