TWI521549B - Coaxial cable - Google Patents

Description

Coaxial cable

The present invention relates to a coaxial cable comprising a center conductor composed of a Cu-Ag alloy wire, and a coaxial cable bundle bundled with the plurality of coaxial cables. More particularly, the present invention relates to a coaxial cable in which the center conductor is a single-wire conductor and has excellent fatigue characteristics.

A coaxial cable is used for wiring of various electrical and electronic devices such as a mobile phone such as a mobile phone or a portable computer, a diagnostic probe for an ultrasonic diagnostic device, an endoscope, and an industrial robot. Since the wiring is often bent or screwed during use, it is desirable that it is difficult to break due to bending or screwing, that is, it is excellent in fatigue characteristics. In order to suppress the disconnection caused by bending or screwing, a method of using a stranded wire in which a plurality of wires are stranded may be cited. Therefore, the general conductor strand conductor of the center conductor of the above coaxial cable was previously used. Moreover, the above-mentioned wire is generally composed of pure copper.

In recent years, with the miniaturization of the above-mentioned electric and electronic equipment, the coaxial cable has been continuously thinned. Therefore, the wire constituting the center conductor must also be thinned, but the small diameter may cause wire breakage (linear difference) during the wire drawing process, or it may be difficult to twist even if the wire is stretched, or may be broken during stranding. Line (twist linearity difference). In addition, when the center conductor of the coaxial cable is connected to an electronic circuit board or the like, the stranded wires are scattered when the end-to-end connection process such as soldering is performed, and the wiring patterns on the substrate are short-circuited via the wires. In response to this, Patent Document 1 proposes to set the center conductor as a single-wire conductor composed of a Cu-Ag alloy. The Cu-Ag alloy has higher strength than pure copper, and by using a single-wire conductor, it is possible to improve the stretch linearity, omit the stranding step, and improve the workability of the terminal connection treatment.

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2008-258172

The coaxial cable described in Patent Document 1 is mainly for a relatively long person such as a wiring of a medical device or an industrial robot. On the other hand, wiring of relatively small electrical and electronic devices such as mobile phones and laptop computers is short. Specifically, it is 1 m (1000 mm) or less, and the length of 50 cm (500 mm) or less and 30 cm (300 mm) or less is shorter depending on the application. Further, it is desirable to develop a coaxial cable having a relatively short wiring length of 1000 mm or less.

For example, when a cable of a shorter length is applied with the same twisting of a cable having a longer length, in a shorter cable, the proportion of the area subjected to the fatigue caused by the screwing is larger than the total length, and the degree of fatigue is large. Also larger. Therefore, if only a long cable is simply shortened, it is difficult to ensure the same level or more than the longer cable. In particular, as described above, if a single-wire conductor is set in consideration of linearity or productivity, it is more likely to be fatigued than a stranded conductor. Therefore, it is desired to develop a degree equivalent to or equal to that of a coaxial cable including a stranded conductor. A coaxial cable with a single conductor of the characteristics.

Accordingly, it is an object of the present invention to provide a coaxial cable in which the center conductor is a single-wire conductor and has excellent fatigue characteristics. Still another object of the present invention is to provide a coaxial cable bundle in which a plurality of the above coaxial cables are bundled.

The inventors of the present invention have selected Ag as an additive element having a relatively low conductivity and a strength-improving effect, and a Cu-Ag alloy wire for a coaxial cable having a relatively short length as described above and having a center conductor Various studies have been conducted on the composition of the single-wire conductor in the case of excellent fatigue characteristics. As a result, it has been found that a Cu-Ag alloy wire satisfying a specific range by the content and size (diameter) of Ag constitutes a center conductor in such a manner that electrical conductivity and tensile strength satisfy a specific range, whereby relatively short strips can be obtained and The center conductor is a single-wire conductor, but the coaxial cable is still excellent in fatigue characteristics. The present invention is based on the above-mentioned insights.

The coaxial cable of the present invention comprises a center conductor, an electrical insulating layer disposed on the outer circumference of the center conductor, and an outer conductor disposed on the outer circumference of the electrical insulating layer and coaxially disposed with the center conductor, and having a length of 1000 mm or less Relatively short cable. Further, the center conductor of the coaxial cable is a single-wire conductor composed of one bare wire, and the bare wire includes a Cu-Ag alloy containing Ag 5 mass% or more and 15 mass% or less and the remainder being Cu and impurities. a Cu-Ag alloy wire; and an Ag plating layer or a Sn plating layer disposed on the periphery of the Cu-Ag alloy wire. Further, 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 satisfies 1330 MPa or more.

The coaxial cable of the present invention can improve the linearity of the extension, the omission of the stranding step, and the workability of the end-end connection processing by making the center conductor a single-wire conductor, compared with the case of a stranded conductor. Further, the coaxial cable of the present invention has a center conductor composed of a specific composition of a specific range of Ag as described above, and a Cu-Ag alloy wire satisfying a specific size (diameter) as a main component, and electrical conductivity and The tensile strength satisfies a specific range, and even if the cable is a relatively short strip of 1 m or less and the center conductor is a single-wire conductor, the resistance to screwing or bending is excellent, and the fatigue characteristics are excellent.

In one aspect of the invention, the ratio of the thickness of the electrical insulating layer to the diameter of the center conductor is 65% or more, and the attenuation of the coaxial cable at 1 GHz is 12 dB/m or less. Moreover, as one aspect of the present invention, the number of cycles of the coaxial cable in the following fatigue test is 200,000 or more.

[stress test]

A cable bundle sample of 30 to 40 coaxial cables was bundled, and each end portion of the sample was fixed to a jig capable of biaxial rotation, and the following opening and closing and screwing tests were performed. The two axes are arranged such that one of the axes is orthogonal to the other axis.

Opening and closing and screwing test The rotation angle of the one side is the rotation axis θ: 0° to 90°. Then, the other axis is used as the rotation axis, and the rotation angle α is rotated from 0° to 180°, and further, the rotation angle α is 180° to 0°. Then, the rotation axis θ: 90° to 0° is closed by the axis of the above one. These series of biaxial rotation operations were performed as one cycle at a speed of about 11 seconds/cycle.

According to the above aspect, the amount of attenuation can be reduced by making the thickness of the electrically insulating layer sufficiently thick, and it can be preferably used as a signal transmission line. Further, according to the above aspect, even if it is a short coaxial cable and the center conductor is a single-wire conductor, it has sufficient fatigue characteristics, so that it can be preferably used for, for example, a small-sized electric and electronic machine having a two-axis rotating mechanism. The sex is the wiring of the mobile phone. The larger the ratio of the thickness of the electrical insulating layer is, the smaller the amount of attenuation is, so it is preferably 75% or more, and more preferably 80% or more. However, if the thickness of the electrical insulating layer is too thick, the cable becomes thick, so that it is preferable. It is 100% or less. Further, the smaller the amount of attenuation, the better the signal transmission line, and therefore the lower limit is not particularly set.

According to an aspect of the present invention, the diameter of the center conductor is 90% or less of a diameter of a center conductor of the comparative cable below, and an outer diameter of the electrical insulating layer is equal to an outer diameter of an electrical insulating layer of the comparison cable. The attenuation at 1 GHz of the coaxial cable is equal to or less than the attenuation of the comparison cable. Moreover, as one aspect of the present invention, the number of cycles of the coaxial cable in the fatigue test is equal to or higher than the number of cycles of the comparison cable.

[Comparative cable]

The center conductor is a stranded conductor of a stranded bare wire formed of a Cu-Ag alloy containing 0.6% by mass of Ag and the remainder consisting of Cu and impurities, and the diameter of the bare wire for each strand is 16 μm. (Drop wire conductor diameter: 48 μm). Further, the electrical insulating layer of the comparative cable is made of the same material as that of the electrical insulating layer constituting the coaxial cable.

[stress test]

A cable bundle sample in which 30 to 40 of the coaxial cables are bundled, and a cable bundle comparison sample in which the same number of the comparison cables as the coaxial cable are bundled, and each end portion of each sample is fixed The above-mentioned opening and closing and screwing tests were carried out on a jig capable of rotating on two axes.

The coaxial cable of the above form is thinner than the comparative cable of the coaxial cable in which the analog center conductor is a common twisted conductor. Further, since the outer diameter of the electrical insulating layer of the above-described form and the electrical insulating layer of the comparative cable (the total diameter of the center conductor and the electrical insulating layer) are equal, the thickness of the electrical insulating layer of the coaxial cable of the above-described form is relatively thick. In this manner, the amount of attenuation can be reduced by making the electrically insulating layer thick enough, and therefore, according to the above aspect, it can be preferably used for a signal transmission line. Further, according to the above aspect, even if it is a short coaxial cable and the center conductor is a single-wire conductor, it has fatigue characteristics equal to or higher than that of a comparative cable including a stranded conductor. Therefore, the coaxial cable of the above-described form can be preferably used for wiring of various electric and electronic machines having a two-axis rotating mechanism, in particular, small machines such as mobile phones.

The coaxial cable of the present invention can be used as it is, or it can be used in a form in which a plurality of bundles (the coaxial cable bundle of the present invention) are bundled. Since the bundle of coaxial cables is bundled, it is very easy to handle.

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

Hereinafter, the present invention will be described in more detail. In the description of the drawings, the same components are denoted by the same reference numerals, and the description thereof will not be repeated. Moreover, the dimensional ratio of the drawings does not necessarily coincide with those described.

[coaxial cable]

<Overall composition>

As shown in FIG. 1, the coaxial cable 1 of the present invention has a typical structure including a center conductor 10, an outer conductor 14 disposed coaxially with the center conductor 10, and an electrical insulating layer 13 for insulating the two conductors 10, 14. Further, it includes a cover 15 that covers the outer periphery of the outer conductor 14. 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. As a structural feature of the coaxial cable of the present invention, as described below, the center conductor is a single-wire conductor, and the diameter of the bare wire constituting the single-wire conductor satisfies a specific range and the length is relatively short. Moreover, as a more preferable aspect, as described below, the thickness of the electrically insulating layer satisfies a specific range.

<length>

The length of the coaxial cable of the present invention is set to be 1000 mm or less. Depending on the application, a form of 500 mm or less and 300 mm or less can be cited. This length can be appropriately selected depending on the purpose. If a long coaxial cable is manufactured and cut to a desired length, the coaxial cable of the present invention can be manufactured with good productivity.

<Center conductor>

[composition]

The main wire constituting the center conductor is a Cu-Ag alloy wire composed of a binary alloy (Cu-Ag alloy) containing a specific amount of Ag. When the content of Ag is 5% by mass or more, it is easy to obtain an improvement in strength due to precipitation strengthening of Ag, and an effect of improving fatigue characteristics, and the more the Ag is, the more excellent the fatigue characteristics are. However, in the case of more than 15% by mass, the interfacial resistance between Cu-Ag increases due to excessive precipitation of Ag, and thus the electrical conductivity is lowered. Therefore, in order to achieve excellent fatigue characteristics and high electrical conductivity, in the present invention, the content of Ag is set to 5 mass% or more and 15 mass% or less.

[wire diameter]

The above 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 be 15 μm (0.015 mm) or more and 50 μm (0.05 mm) or less as a size sufficient for use as a single-wire conductor. By setting it to 15 μm or more, it is possible to suppress a decrease in electrical conductivity due to excessive processing at the time of wire drawing, thereby having a conductivity of a specific size, and it is difficult to cause wire breakage during wire drawing, excellent linearity, and production of wire. Excellent sex. Further, by setting it to 50 μm or less, a narrow-diameter cable in which the cable diameter does not become excessive can be obtained. More preferably, it is 45 μm (0.045 mm) or less, and further preferably 40 μm (0.04 mm) or less. The diameter of the center conductor including the Cu-Ag alloy wire and the plating layer described below is also preferably 50 μm or less, more preferably 45 μm or less, still more preferably 40 μm or less. Further, if the diameter of the center conductor is 90% or less of the diameter of the center conductor of the comparison cable of the above-mentioned general-purpose coaxial cable, the effect of reducing the diameter of the coaxial cable which is more common can be obtained. However, as described above, if it is too fine, the conductivity is lowered or the productivity is lowered. Therefore, the diameter of the center conductor is preferably 30% or more of the diameter of the center conductor of the cable. The diameter of the Cu-Ag alloy wire can be changed by appropriately changing the degree of processing during the wire drawing process, and the diameter of the center conductor including the Cu-Ag alloy wire can be appropriately changed by the diameter of the above Cu-Ag alloy wire, and The thickness of the plating layer changes.

[characteristic]

Here, in the Cu-Ag alloy, the tensile strength and the electrical conductivity are in a trade-off relationship, and the content of Ag is approximately proportional to the tensile strength. The present inventors have found from these relationships that the center conductor has a range of sufficient fatigue characteristics when it is set as a single-wire conductor, and the present invention defines the range. Specifically, the conductivity of the center conductor including the Cu-Ag alloy wire is set to 50% IACS or more, and the tensile strength is set to 1330 MPa or more. The electric conductivity and the tensile strength are preferably as high as possible, and the electric conductivity is preferably 55% IACS or more, more preferably 60% IACS or more, and the tensile strength is preferably 1400 MPa or more. It is preferably 1500 MPa or more. The tensile strength tends to increase by increasing the content of Ag, or increasing the degree of processing at the time of stretching, or by adjusting the existence state of precipitates of Ag by heat treatment, and the conductivity is decreased by reducing the content of Ag or by heat treatment. The tendency of the precipitate of Ag to be analyzed and increased. In order to form desired characteristics, it is only necessary to adjust the content of Ag or the manufacturing conditions.

[plating layer]

When a coaxial cable is connected to a circuit board or the like, solder is usually used. By including 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. The thickness of the plating layer can be appropriately selected, and even if it is 1 μm or less, especially 0.3 μm or less, the wettability with the solder can be sufficiently improved, and the center conductor of the small diameter of the center conductor does not become excessive, and the center conductor can be obtained. Therefore, it is better. The plating layer is easy to use when the thickness is from 0.8 μm to 0.2 μm.

<Electrical insulation layer>

The constituent material of the electrical insulating layer formed on the outer periphery of the center conductor is preferably an insulating resin which is excellent in electrical insulating properties and flexibility, and is typically an insulating resin. Specific examples thereof include an epoxy resin, a polyester resin, a polyurethane resin, a polyvinyl alcohol resin, a vinyl chloride resin, a vinyl ester resin, an acrylic resin, and an epoxy acrylate resin. A diallyl phthalate-based resin, a phenol-based resin, a polyamine-based resin, a polyimide-based resin, or a melamine-based resin. More preferably, it is a fluorine-based resin such as a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA, Polyfluoroalkoxy).

The above-mentioned electrically insulating layer tends to reduce the amount of attenuation as the thickness thereof is thicker. In order to obtain this effect, the thickness of the electrically insulating layer is preferably such that the ratio of the thickness of the electrically insulating layer to the diameter of the center conductor is 65% or more, and more preferably 75% or more. Moreover, the diameter of the center conductor of the coaxial cable is less than 90% of the diameter of the center conductor of the comparison cable, and the outer diameter of the electrical insulation layer of the coaxial cable is equal to the outer diameter of the electrical insulation layer of the comparison cable. The thinner the center conductor of the coaxial cable, the thicker the electrical insulation layer is than the comparative cable. Therefore, in this aspect, as the diameter of the center conductor is made smaller, the amount of attenuation can be reduced. As described above, since the Cu-Ag alloy wire has a finer diameter of 40 μm or less, the electrically insulating layer can be formed relatively thickly, so that the amount of attenuation can be reduced. Further, in the case where the electrically insulating layer is formed of a material having a low dielectric constant (for example, 50 pF/m or less), it is expected that the amount of attenuation can be reduced even if the thickness is somewhat thin.

<Other composition>

The external conductor or the exterior can be suitably constructed using a coaxial cable of a known small diameter. The external conductive system functions as a shielding layer, and the constituent material thereof can preferably utilize a wire composed of Cu or a Cu-Ag alloy. The form in which the strip wire or the round wire is wound around the outer circumference of the electrical insulating layer (wound in a spiral shape) or the knitted component obtained by knitting the wire is placed on the outer periphery of the electrically insulating layer, etc. . The constituent material of the exterior can also preferably utilize a resin excellent in electrical insulation and flexibility as described in the electrical insulating layer, particularly a thermoplastic resin.

[coaxial cable bundle]

The coaxial cable bundle of the present invention includes a plurality of coaxial cables of the fundamental invention and a bundle member for integrating the cables. For example, a state in which a plurality of coaxial cables are arranged in parallel and wound around a belt to be integrated, a plurality of coaxial cables are arranged in parallel, and a resin or the like is extruded to the outer periphery thereof to be integrated. . Moreover, as one form of the coaxial cable bundle, a connection member such as a connector is attached to both end portions. According to this aspect, since a plurality of coaxial cables can be attached to an electric or electronic device at one time, the connection workability is excellent. A typical form includes a connector in which a coaxial cable group integrated by a bundling member has a connector. In a form in which the connecting member such as the connector is not provided, solder is directly applied to the end portion of the coaxial cable group to be connected to the substrate or the like. A known technique can be suitably used for the material, the forming method, the mounting method, and the like of the connecting member or the bundling member.

[use]

Since the coaxial cable and the coaxial cable bundle of the present invention have a relatively short length of 1000 mm or less, they can be preferably used for wiring of small electric and electronic equipment, and are typically portable such as a mobile phone or a portable computer. Machines, especially those with a two-axis rotating mechanism. Furthermore, when the length exceeds 1000 mm, it can also be used for wiring of medical equipment or industrial robots.

[Characteristics of Coaxial Cable]

In the case where the coaxial cable having the above-described configuration is subjected to the above-described fatigue test, the number of cycles is 200,000 times or more, or the number of cycles of the comparison cable or more is equal to or higher than that of the comparative cable. Further, the above-mentioned electrically insulating layer has a specific thickness of a coaxial cable having an attenuation of 12 dB/m or less at 1 GHz, or is equal to or less than that of a comparative cable, and is difficult to be attenuated. Therefore, the coaxial cable or coaxial cable bundle of the present invention can be preferably used for signal transmission lines.

[Production method]

The coaxial cable of the present invention is typically manufactured by a manufacturing process such as manufacture of a central conductor, formation of an electrically insulating layer, formation of an outer conductor, and formation of an exterior. In particular, the basic manufacturing steps of the center conductor include the manufacture of the cast material and the wire drawing process. Intermediate heat treatment can also be carried out during the wire drawing process. The timing of carrying out the intermediate heat treatment may be appropriately selected or may not be performed in the intermediate heat treatment.

The inventors of the present invention obtained the following findings when producing a Cu-Ag alloy wire having a content of Ag within the above specific range and having a specific size, specific conductivity, and tensile strength. In other words, when the content of Ag is relatively small in the range of 5 mass% or more and 15 mass% or less (5 mass% or more and 10 mass% or less), even if the intermediate heat treatment is not performed during the wire drawing process, A Cu-Ag alloy wire having a conductivity of 50% IACS or more and a tensile strength of 1330 MPa or more can be obtained. In a relatively large case (about 10% by mass or more), it is preferred to carry out an intermediate heat treatment during the wire drawing process. Further, the more the content of Ag is, the more the timing of performing the intermediate heat treatment is delayed (the intermediate heat treatment is performed after the wire diameter becomes small). In the present invention, the range of the content of Ag is specified to a certain extent, and the specific Cu-Ag alloy wire can be produced with good productivity by establishing the manufacturing step based on the content of Ag as described above, and industrially The words are significant.

When a cast material is produced, the raw material is prepared in such a manner as to become a specific composition. When the raw material Cu or the raw material Ag is used in a high purity such as four nine (purity: 99.99%) or more, the amount of impurities is small, and when a wire having a small diameter is produced, foreign matter that may participate in disconnection can be reduced.

The cast material may be subjected to a heat treatment such as a solution treatment or a homogenization treatment before the wire drawing process. The conditions of the solution treatment include a heating temperature of 600 ° C or more and 850 ° C or less, a holding time of 0.5 hours or more, and a cooling rate of 1.5 ° C/sec or more. By performing the solution treatment under the conditions, Ag can be sufficiently dissolved in Cu. The longer the retention time is, the more the Ag tends to be sufficiently dissolved in Cu, and therefore it is preferable to appropriately select it within a range that does not cause a decrease in productivity. The faster the cooling rate is, the more the precipitation of Ag can be suppressed. Therefore, it is preferable to set the rapid cooling to 1.5 ° C / sec or more and further 3 ° C / sec or more. Such rapid cooling can be achieved by appropriately utilizing a forced cooling means, for example, direct cooling using a fluid refrigerant such as water or oil, sand, blast using a blower or the like, or other water-cooled copper block. When the above-described solution treatment is carried out, if an intermediate heat treatment is performed during the wire drawing to precipitate the solid solution Ag, the strength (fatigue property) due to precipitation strengthening can be improved. The conditions of the homogenization treatment include a heating temperature of 500 ° C or higher, a holding time of 0.5 hour or more, and a cooling rate of 50 ° C / sec or less.

The drawing line (typically a cold room) is machined through a plurality of channels until the final wire diameter is formed. The degree of processing of each channel may be appropriately adjusted in consideration of the composition (content of Ag), the final wire diameter, and the like. By stretching the wire, one part of the precipitated Ag is stretched into a fiber shape, and it is considered that the strength (fatigue property) can be improved by the strengthening of the fibrous Ag.

The intermediate heat treatment carried out during the processing of the wire is mainly for the purpose of precipitating Ag to obtain an effect of improving the strength of precipitation strengthening. We believe that by this heat treatment, one part of the precipitated Ag can be changed into a very fine grain of the nanometer order. It is considered that a Cu-Ag alloy wire having high conductivity and high strength can be produced by the presence of the fibrous Ag or by uniformly dispersing Ag in the above-mentioned ultrafine particles or by coexisting the two.

The intermediate heat treatment may be carried out plural times, and if it is carried out only once, the number of production steps is small and the productivity is excellent. In the case where the plurality of times are performed, it is expected that the Ag can be sufficiently precipitated to increase the strength or the electrical conductivity, or the processing deformation introduced by the wire drawing process can be removed to improve the electrical conductivity, or the wire drawing process after the heat treatment can be easily performed.

The conditions of the above intermediate heat treatment include a heating temperature of 300 ° C or more and a holding time of 0.5 hour or more. By setting the heating temperature to 300 ° C or higher and the holding time to 0.5 hour or longer, Ag can be sufficiently precipitated or the processing deformation can be sufficiently removed. The higher the heating temperature and the longer the holding time, the easier it is to precipitate Ag. Further, by setting the heating temperature to 600 ° C or lower, it is possible to suppress a decrease in electrical conductivity due to the solid solution of Ag again in Cu. Therefore, the heating temperature is preferably 600 ° C or lower, more preferably 350 ° C or higher and 550 ° C or lower, further preferably 400 ° C or higher and 450 ° C or lower, and the holding time is preferably 0.5 hour or longer and 10 hours or shorter. The cooling method in the intermediate heat treatment is, for example, a furnace which is placed in a heat treatment furnace and cooled by natural cooling.

A plating layer is formed on the wire of the final wire diameter during the wire drawing process. The plating method is typically exemplified by electroplating or electroless plating.

The formation of the outer conductor and the exterior, and the formation of the coaxial cable bundle can be appropriately determined by a known method.

[Test example]

A Cu-Ag alloy wire was produced under various conditions, and a coaxial cable using the Cu-Ag alloy wire as a center conductor was produced, and the obtained coaxial cable was investigated for mechanical properties, fatigue characteristics, attenuation characteristics, and state at the time of terminal treatment.

The Cu-Ag alloy wire system was produced in the following manner. An electrolytic copper having a purity of 99.99% or more is prepared as a raw material Cu, and silver particles (Ag) having a purity of 99.99% or more are prepared as a raw material Ag, and are put into a high-purity carbon crucible and vacuum-melted in a continuous casting apparatus to form a molten Cu. And mixed molten metal of Ag. As shown in Table 1, the amount of silver particles added was 0.6% by mass (sample No. 100) and 5% by mass to 15% by mass (sample No. 1) with respect to the Ag content (concentration) of the mixed molten metal. Adjust to the method of ~5).

Using the obtained mixed molten metal, continuous casting is performed in a high-purity carbon mold to thereby produce a cross-sectional circular shape of the casting size ( Φ 22 mm, Φ 16 mm, Φ 8.0 mm) shown in Table 1. Casting material.

The obtained cast material was subjected to cold-stretching processing, and the bare wire of the wire diameter (final wire diameter) shown in Table 1 was obtained (sample No. 100 was a bare wire for stranded wire). When Sample Nos. 2 to 5 were formed into the wire diameter (size) shown in Table 1 during the wire drawing process, the intermediate heat treatment was carried out under the conditions shown in Table 1. Further, in any of the samples, when the wire diameter was Φ 0.36 mm during the wire drawing process, the plating layer of the material shown in Table 1 was formed by electroplating, and then the wire drawing process was continued. Therefore, with respect to the obtained bare wire, any of the samples contained a plating layer on the outer periphery of the Cu-Ag alloy wire. Here, the thickness of the plating layer of any of the samples is 0.3 μm or less.

Sample Nos. 1 to 5 did not break once until 2 kg of the bare wire of the above final wire diameter was produced, but sample No. 100 was broken 13 times as shown in Table 1.

The tensile strength (MPa) and electrical conductivity (% IACS) of the obtained bare wire including the plating layer were measured. The results are shown in Table 1. The tensile strength was measured in accordance with the regulations of JIS Z 2241 (1998) (punctuation distance GL: 250 mm). The conductivity was measured by the bridge method. Further, when the tensile strength or electrical conductivity of the center conductor is measured for the coaxial cable including the center conductor, the electrical insulating layer, the outer conductor, and the outer casing, the center conductor may be appropriately taken out as long as the coaxial cable is disassembled.

The bare wires including the plating layers of Sample Nos. 1 to 5 were used as the center conductor, and the materials shown in Table 1 were used for the outer circumference of the center conductor, and the electrical properties were formed by extrusion to have the thickness shown in Table 1. The insulating layer is further formed on the outer circumference of the outer conductor and the outer casing to form a coaxial cable. The external conductor and the exterior are made of the same materials, and the same materials are used in any of the samples. After preparing the sample No.100 line 7 of diameter Φ 16 μm with bare twisted strands performed, and the sample No.1 ~ 5 in the same manner using the same material forming the electrically insulating layer, an outer conductor, an exterior, A coaxial cable (hereinafter referred to as a comparison cable) is produced. The electrical insulating layers of the coaxial cables of Sample Nos. 1 to 5 were uniform in thickness throughout the entire circumference of the center conductor. On the other hand, the comparative cable of the sample No. 100 has a concavo-convex shape due to the center conductor, and therefore the electrically insulating layer has a non-uniform thickness throughout the entire circumference of the center conductor. Therefore, the thickness of the portion where the thickness of the electrical insulating layer in the comparative cable of the sample No. 100 is the thinnest (the portion covering the crown portion of the strand) is shown in Table 1. Further, since the electrical insulating layers of Sample Nos. 1 to 5 and 100 were all made of the same material, the dielectric constants were equal. The diameter (wire diameter) of the center conductor of the coaxial cable and the thickness of the electrical insulating layer can be easily measured by observing the cross section by a microscope.

The comparative cable of each of the obtained sample Nos. 1 to 5 and the sample No. 100 was measured using a commercially available device (here, Network Analyzer, HP8753ES of Agilent Technology Co., Ltd.). Attenuation amount (dB/m). The attenuation amount at a frequency of 1 GHz is shown in Table 1. Further, the attenuation amounts of the sample Nos. 2, 3, and 100 at various frequencies are shown in Fig. 4 . Here, when the amount of attenuation is measured, the length of the cable of each sample is set to 1 m in order to facilitate calculation, and the length can also be shortened.

The obtained coaxial cable of sample Nos. 1 to 5 and the comparative cable of sample No. 100 were subjected to a fatigue test of a mobile phone including a two-axis rotating mechanism, and the number of cycles was measured. In the fatigue test, the following cable bundle samples and cable bundle comparison samples were prepared, and each cable bundle sample and the cable bundle comparative sample were fixed to the following jig.

A coaxial cable of 40 sample Nos. 1 to 5 and a comparison cable of sample No. 100 (each having a length of about 200 mm) were prepared, and a foamed fluororesin tape was wound around the cable group which was juxtaposed (here A bundle of cable bundles (sample Nos. 1 to 5) and a cable bundle comparison sample (sample No. 100) were produced by binding to Poreflon (registered trademark of Sumitomo Electric Industries Co., Ltd.).

Next, the jig used in the fatigue test will be described with reference to Fig. 2 . The jig 100 includes a mechanism capable of biaxial rotation, and includes a support leg 101, a movable plate 102 rotatably supported relative to the support leg 101, and a first support capable of rotating the movable plate 102 with respect to the support leg 101. The rotating shaft 103 and the second rotating shaft 105. The second rotating shaft 105 is disposed to be orthogonal to each other with respect to the first rotating shaft 103, and the movable plate 102 is rotatably attached to the support frame 104. Here, the movable plate 102 is pivoted on the first rotating shaft 103 with the first rotating shaft 103 as an axis and the rotation angle θ: 0° to 180°. This rotation operation is an operation of drawing an arc along the left side to the upper side to the right side in FIG. 2(B), and is a shaft portion 110 shown in FIG. 3 (schematically showing the first rotation axis and the second rotation) The shafts are openably and closably supported by the pair of plate-like portions 111 and 112 with the shaft portion 110 (first rotating shaft) as an axis, and the operation of the opening and closing operation is simulated. Further, the movable plate 102 can be rotated in a state where the rotation angle θ is 90° on the first rotation axis 103 (the state shown in the part of FIG. 2(B) and the part of FIG. 3(B)), and further The second rotating shaft 105 is pivoted to the second rotating shaft 105 by a rotation angle α of the shaft: 0° to 180°. This rotation operation is an operation of drawing an arc along the left side to the front side to the right side in FIG. 2(B), and as shown in part (B) to FIG. 3 (D), one of the plate-like portions 112 is provided. The support leg 101 is pivoted by the rotation angle θ: 0° to 90° with the shaft portion 110 (first rotation axis) as an axis, and the other plate portion 111 is orthogonal to the plate portion 112. In this state, the shaft portion 110 (second rotation axis) is used as an axis to simulate a state in which the plate-like portion 111 is rotated by a rotation angle α: 0° to 180°, or a rotation angle α: 180° to 0°. The state of the rotation action. Here, the inner diameters of the hinge cylinders constituting the first rotating shaft 103 and the second rotating shaft 105 are both set to 2 mm, and the thickness of the movable plate 102 is set to 1 mm.

One end of the prepared cable bundle sample 20 or the cable bundle comparative sample is fixed to the support leg 101 as shown in part (A) of FIG. 2, and the other end is fixed to the surface of the movable plate 102. The cable bundle sample 20 or the cable bundle comparative sample is appropriately bent when introduced into the hinge cylinder (support frame 104) constituting the first rotary shaft 103 or the hinge cylinder. Here, as shown in part (A) of Fig. 2, the bending radius R ₁ = 5 mm and the bending radius R ₂ = 3 mm are set, from the fixed portion of the cable bundle sample 20 or one end of the cable bundle comparison sample to The distance L1 = 3 mm from the center of the first rotating shaft 103 (indicated by a dotted line in Fig. 2(A)), and the distance L2 = 5 from the center of the first rotating shaft 103 to the surface of the movable plate 102 Mm, the distance L3 = 10 mm from the fixed portion of the cable bundle sample 20 or the cable bundle comparison sample to the center of the second rotating shaft 105.

The cable bundle sample 20 and the cable bundle comparison sample are respectively fixed to the jig 100, and the opening and closing operation of the analog mobile phone and the following opening and closing and screwing tests of the screen rotation operation of the mobile phone are performed. Specifically, as shown in part (A) of FIG. 3, the state in which the pair of plate-like portions 111, 112 are closed is the initial state, as shown in the portion of FIG. 3(B), the shaft portion 110 (the first rotation axis) The rotation axis is an opening operation for rotating the plate-like portion 111 from the rotation angle θ: 0° to 90°, and secondly, the shaft portion 110 (second rotation axis) is the axis, and the plate-like portion 111 is rotated from the rotation angle α. :0° is rotated to 180°, and as shown in part (C) of FIG. 3, the surface f of the plate-like portion 111 and the back surface b are opposite to each other. Then, the plate-like portion 111 is reversely rotated from the rotation angle α:180° to 0°, as shown in part (D) of FIG. 3, to restore the back surface b and the surface f to the orientation before the rotation (Fig. 3(B) After the portion is in the same direction, the closing operation of rotating the plate portion 111 from the rotation angle θ: 90° to 0° is performed with the shaft portion 110 (first rotation axis) as an axis, as shown in part (E) of FIG. 3 . The state returns to the state in which the pair of plate-like portions 111, 112 are closed. These series of biaxial rotation operations were used for one cycle of the fatigue test, and the test was performed at a speed of about 11 seconds/cycle, and the number of times until at least one of the 40 cables of each sample was broken was measured.

The cable bundle samples of the samples No. 1 and 3 and the cable bundle comparison sample of the sample No. 100 were subjected to a simulation of the actual end-to-end connection treatment, and the deformation workability and the connectivity to the substrate were examined. The results are shown in Table 1. Deformation processability is carried out by clamping the end of each cable bundle sample and the end of the cable bundle comparison sample into the metal mold, and applying a load from two different directions, that is, applying two load weights to compress and deform the end. Before and after the compression, the cross-sectional shape of the center conductor contained in each sample was observed by a microscope and evaluated. Further, before the application of the total weight twice (before compression deformation), the cross-section of the center conductor of any sample (the bare line constituting the strand in sample No. 100) was substantially rounded. The connectivity to the substrate was examined by bonding the solder to the substrate after the compression deformation described above.

As shown in Table 1, a Cu-Ag alloy wire having a content of Ag of 5 mass% or more and 15 mass% or less and a diameter of 15 μm to 50 μm is used as a center conductor, and the center conductor is electrically conductive. Among the samples No. 1 to 3 and 5 having a rate of 50% IACS or more and a tensile strength of 1,330 MPa or more, even if the center conductor was a single wire, the number of cycles in the above-described fatigue test was 200,000 or more, and the fatigue characteristics were excellent. Further, it was found that Sample Nos. 1 to 3 and 5 were superior in fatigue characteristics to the comparative cable No. 100 containing the stranded conductor or the sample No. 4 having less Ag.

Further, when the thickness of the electrically insulating layer is 65% or more with respect to the diameter (wire diameter) of the center conductor, the amount of attenuation is small and the attenuation characteristics are excellent. It can also be seen that when the wire diameter of the single-wire conductor is less than 90% of the wire diameter of the stranded conductor, and the outer diameter of the electrical insulating layer is the same as that of the comparative cable including the stranded conductor, the coaxial cable containing the single-wire conductor is electrically insulated. Since the thickness of the layer is relatively thick, the attenuation characteristics are excellent. Specifically, the attenuation amount of the coaxial cables is equal to or less than the same degree of the comparison cable. Further, as shown in FIG. 4, it is found that the attenuation amounts of the samples No. 2 and 3 before 2.5 GHz are smaller than the sample No. 100, and the attenuation at 600 MHz is 9 dB/m or less, and the attenuation at 750 MHz. It is 10 dB/m or less and has excellent attenuation characteristics. In particular, Sample No. 2 has an attenuation of about 15 dB/m at 2 GHz and an attenuation of 20 dB/m at 3 GHz, which is superior in attenuation characteristics.

Further, as shown in Table 1, it is understood that when the content of Ag is in the range of 5% by mass or more and 15% by mass or less, and Ag is relatively small, the conductivity is 50% IACS even if the intermediate heat treatment is omitted. The above bare wire with tensile strength of 1330 MPa or more, in the case of relatively large Ag, the more Ag, the smaller the wire diameter for performing the intermediate heat treatment during the wire drawing process, thereby obtaining a conductivity of 50%. A bare wire having an IACS or more and a tensile strength of 1330 MPa or more.

Further, in Sample Nos. 1 and 3, the cross section after the above-described compression deformation was deformed into an elliptical shape, and the shape thereof was reproducible (the unevenness of the cross-sectional shape of each compression deformation was small). On the other hand, in sample No. 100, the bare wires constituting the strands were scattered, and the cross-sectional shape was different each time the compression was deformed. Further, in the sample Nos. 1 and 3, since the cross section of the center conductor was deformed into a flat elliptical shape, the flat surface of the ellipse can be satisfactorily connected to the substrate as a contact. On the other hand, in the sample No. 100, since the bare wires constituting the strands are scattered, it is difficult to connect, and in order to be uniformly fixed to the substrate, it is necessary to perform preliminary welding at the tip end portion. From this result, it is understood that the center conductor is set to be a single-wire conductor, and the end of the coaxial cable is excellent in workability and connectivity to a substrate or the like.

As a result of the above test, it is understood that the Cu-Ag alloy wire containing Ag and having a specific size in a specific range is used, and the electrical conductivity and the tensile strength are in a specific range, whereby the center conductor is a single-wire conductor, and excellent fatigue properties can be obtained. Coaxial cable or coaxial cable bundle. Further, it is expected that the coaxial cable or the coaxial cable bundle has fatigue characteristics equal to or higher than the sample No. 100 in which the center conductor is a stranded conductor, and the center conductor can be made thinner, contributing to weight reduction.

It is to be noted that the above-described embodiments can be appropriately modified without departing from the spirit and scope of the invention, and are not limited to the above configuration. For example, the length of the coaxial cable can be appropriately changed, the diameter of the Cu-Ag alloy wire constituting the center conductor, the conductivity of the center conductor, the tensile strength, the thickness of the electrical insulating layer, the material, the forming method, and other manufacturing conditions (middle) Heating temperature during heat treatment, holding time, timing of performing intermediate heat treatment, etc.).

[Industrial availability]

The coaxial cable and the coaxial cable bundle of the present invention can be preferably used for wiring of relatively short strips such as small electronic and electrical equipment wiring such as mobile phones and portable computers.

1. . . Coaxial cable

10. . . Center conductor

11. . . Cu-Ag alloy wire

12. . . Plating layer

13. . . Electrical insulation

14. . . External conductor

15. . . Exterior

20. . . Cable bundle sample

100. . . Fixture

101. . . Support foot

102. . . Movable plate

103. . . First axis of rotation

104. . . Support box

105. . . Second axis of rotation

110. . . Shaft

111, 112. . . Plate

f. . . Surface of the plate portion 111

b. . . The back of the plate portion 111

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of a coaxial cable of the present invention.

Fig. 2 is a schematic explanatory view showing the constitution of a biaxially rotatable jig for fatigue test and the state in which the coaxial cable is fixed. Fig. 2(A) is a front view, and Fig. 2(B) is a side view.

Fig. 3 is a schematic explanatory view showing the steps of the fatigue test.

Fig. 4 is a graph showing the attenuation characteristics of the relationship between the frequency and the attenuation amount in the Cu-Ag alloy wire.

1. . . Coaxial cable

10. . . Center conductor

11. . . Cu-Ag alloy wire

12. . . Plating layer

13. . . Electrical insulation

14. . . External conductor

15. . . Exterior

Claims (6)

A coaxial cable comprising a center conductor, an electrical insulating layer disposed on an outer circumference of the center conductor, and an outer conductor disposed on a periphery of the electrical insulating layer and coaxially disposed with the center conductor, wherein the coaxial cable The length is 1000 mm or less; the center conductor is a single-wire conductor composed of one bare wire; and the bare wire includes a Cu-Ag alloy containing Ag 5 mass% or more and 15 mass% or less and the balance being Cu and impurities. a Cu-Ag alloy wire formed; and an Ag plating layer or a Sn plating layer provided on the outer periphery of the Cu-Ag alloy wire; the Cu-Ag alloy wire has a diameter of 15 μm or more and 50 μm or less; and the conductivity of the center conductor is 50% IACS or more; the tensile strength of the center conductor is 1400 MPa or more; and the number of cycles of the coaxial cable in the fatigue test for performing the biaxial rotation operation is 200,000 times or more. The coaxial cable according to claim 1, wherein a ratio of a thickness of the electrical insulating layer to a diameter of the center conductor is 65% or more; and an attenuation of the coaxial cable at 1 GHz is 12 dB/m or less. The coaxial cable of claim 1 or 2, wherein the diameter of the center conductor is less than 90% of the diameter of the center conductor of the comparison cable, and the outer diameter of the electrical insulation layer is outside the electrical insulation layer of the comparison cable The diameter of the center conductor of the comparative cable is twisted by a Cu-Ag alloy consisting of 0.6% by mass of Ag and the remainder consisting of Cu and impurities. The stranded conductor of the stranded strand is formed, and the diameter of each stranded strand is 16 μm, and the electrical insulating layer of the comparative cable is made of the same material as the material of the electrical insulating layer constituting the coaxial cable. The outer diameter is 0.108 mm; the attenuation of the coaxial cable at 1 GHz is equal to or less than the attenuation of the comparison cable; and the number of cycles of the coaxial cable in the fatigue test of the biaxial rotation operation is the number of cycles of the comparison cable Equal or above. The coaxial cable according to claim 1 or 2, wherein the Cu-Ag alloy wire contains 5% by mass or more and 15% by mass or less of Ag, but does not contain Ag of 5% by mass. The coaxial cable according to claim 3, wherein the Cu-Ag alloy wire contains 5% by mass or more and 15% by mass or less of Ag, but does not contain Ag of 5% by mass. A coaxial cable bundle characterized by a bundle of a plurality of coaxial cables as claimed in any one of claims 1 to 5.