JP2012216526A - Metal-coated carbon fiber wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide metal-coated carbon fibers exhibiting excellent flexibility, and to provide a wire (including a cable) in which high strength and lightweight are attained while satisfying the conductivity as a wire, by fully utilizing the characteristics of the metal-coated carbon fibers.SOLUTION: In the metal-coated carbon fiber wire, an insulation coating layer is provided around a conductor, i.e. metal-coated carbon fibers where one or a plurality of metal layers are provided on an underlying metal layer consisting of one kind selected from nickel, a nickel alloy, palladium, and cobalt provided on the surface of carbon fibers.

Description

  The present invention relates to a metal-coated carbon fiber electric wire that reduces the weight of the electric wire and is excellent in characteristics such as heat resistance, flexibility and strength.

Electric wires have been widely used for wiring in electrical equipment, wiring between communication equipment, wiring of moving bodies, and the like. In recent years, with the improvement in performance of various devices, there is an increasing demand for higher performance on the wires themselves, such as improvement in heat resistance, flexibility, strength, and conductivity.
In addition, in electric wires for mobile objects such as automobiles, railway vehicles, and aircraft, the amount of wires used increases as safety, comfort, and functionality improve, while reducing the weight of the wires is essential to improve fuel efficiency. There is a strong demand for weight reduction of electric wires.

In order to meet such demands, Patent Documents 1 and 2 have a light weight and high strength by covering the surface of carbon fiber having conductivity, high strength and high elastic modulus with a metal such as copper and aluminum. There has been proposed a method of manufacturing an electric wire without metal fatigue. However, when a copper or aluminum film is provided directly on the carbon fiber, the wettability and affinity between the carbon fiber and these metals are poor, and it is extremely difficult to obtain a copper or aluminum film layer that adheres well on the carbon fiber. It was.
If the adhesion between the carbon fiber and the metal film is poor, when the metal-coated carbon fiber is twisted to make a stranded conductor, the metal coating is peeled off by friction, and a very advanced technique is required to make a stranded conductor. .

JP-A-2-189811 JP-A-6-20522

  The present invention provides a metal-coated carbon fiber having excellent flexibility, and further makes use of the characteristics of the metal-coated carbon fiber to achieve high strength and light weight while satisfying the electrical conductivity of the wire. (Including cables, and so on).

  The present invention uses, as a conductor, a metal-coated carbon fiber in which one or more metal layers are provided on a base metal layer made of one selected from nickel, nickel alloy, palladium, and cobalt provided on the surface of the carbon fiber. A metal-coated carbon fiber electric wire in which an insulating coating layer is provided around the conductor.

  The present invention is an electric wire in which an outer conductor, an outer conductor, and a protective insulating layer are provided in this order on the outer periphery of the inner conductor, and either or both of the inner conductor and the outer conductor are carbon A metal-coated carbon fiber wire comprising a metal-coated carbon fiber wire in which one or more metal layers are provided on a base metal layer made of one selected from nickel, nickel alloy, palladium, and cobalt provided on the surface of the fiber. is there.

  The conductor is a single wire of a metal-coated carbon fiber, a bundle of a plurality of the metal-coated carbon fibers, or a plurality of the metal-coated carbon fibers that are concentrically twisted, unilay twisted, collective twisted, or rope twisted It is preferably any one of stranded wires twisted by a method.

  The present invention is a metal-coated carbon fiber electric wire in which the metal-coated carbon fiber electric wire is a conductor, a plurality of metal-coated carbon fiber electric wires provided with an insulating layer around the conductor are bundled, and a protective insulating layer is provided around the bundle. .

  The present invention is an electric wire in which an outer conductor, an outer conductor, and a protective insulating layer are provided in this order on the outer periphery of the inner conductor, and either or both of the inner conductor and the outer conductor are carbon A metal-coated carbon fiber electric wire comprising a metal-coated carbon fiber wire in which one or more metal layers are provided on a base metal layer made of one selected from nickel, nickel alloy, palladium, and cobalt provided on the surface of the fiber. It is a metal-coated carbon fiber electric wire bundled in plural and provided with a protective insulating layer around it.

  The metal layer is preferably a copper layer or a silver layer provided on the copper layer or a tin layer provided on the copper layer.

The carbon fiber diameter X of the metal-coated carbon fiber, the thickness Y of the base metal layer, and the copper layer of the metal-coated carbon fiber wire in which the diameter of the carbon fiber is 3 μm or more and 20 μm or less and the metal layer is a copper layer The ratio of the thickness to the thickness Z is X: Y: Z = 1: (0.004 to 0.071) :( 0.005 to 1.314)
It is preferable that

  The present invention is an electric wire by providing a metal layer with good conductivity on the surface of carbon fiber, which has excellent tensile strength and heat resistance, and is very lightweight. Therefore, a metal-coated carbon fiber electric wire excellent in flexibility can be provided.

FIG. 1 is a cross-sectional view showing one embodiment of a metal-coated carbon fiber wire. FIG. 2 is a sectional view showing a first example of the metal-coated carbon fiber electric wire of the present invention. FIG. 3 is a cross-sectional view showing a second example of the metal-coated carbon fiber electric wire of the present invention. FIG. 4 is a sectional view showing a third example of the metal-coated carbon fiber electric wire of the present invention.

An embodiment of a metal-coated carbon fiber electric wire of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a metal-coated carbon fiber wire 1 serving as a conductor of a metal-coated carbon fiber wire 10 of the present invention is a base metal made of a kind selected from nickel, nickel alloy, palladium, and cobalt on the surface of the carbon fiber wire 2. A layer (coating) 3 is formed, a highly conductive copper layer (coating) 4 is formed thereon, and a silver layer or a tin layer 5 is provided on the copper layer 4 as necessary. In the present invention, the copper layer 4 alone or a combination of the copper layer 4 and the silver layer or tin layer 5 is expressed as a metal layer.

  The metal-coated carbon fiber electric wire of the present invention is an electric wire using the metal-coated carbon fiber wire 1 as a conductor. As the conductor of the electric wire, the metal-coated carbon fiber wire 1 is a single wire, a bundle of a plurality of wires, or a stranded wire twisted by various twisting methods to form the wire conductor 11 (see FIG. 2).

  FIG. 2 shows a metal-coated carbon fiber electric wire 10 using a metal-coated carbon fiber wire as a conductor. The conductor 11 is the wire conductor 11 as a single wire, a bundle of bundles of the metal-coated carbon fiber wires 1 or a twisted wire twisted by various twisting methods. In FIG. 2, a bundle of 1000 metal-coated carbon fiber wires is used as the wire conductor 11. An insulating layer 12 is provided on the outer periphery of the conductor (bundle wire) 11 to constitute a metal-coated carbon fiber electric wire 10.

  A metal-coated carbon fiber electric wire 20 shown in FIG. 3 is a metal-coated carbon fiber electric wire 20 in which three metal-coated carbon fiber electric wires 10 are twisted with three ropes and a protective coating layer 21 is provided on the outer periphery thereof.

  A metal-coated carbon fiber electric wire 30 shown in FIG. 4 is an electric wire 30 in which an inner conductor 31 and an outer periphery of the inner conductor 31 are provided with an insulating layer 32, an outer conductor 33, and a protective covering layer 34 in this order. The inner conductor 31 is constituted by a single wire, bundled wire or stranded wire of the metal-coated carbon fiber wire 1 or is formed by a copper wire (including a copper alloy wire). The outer conductor 33 is composed of a bundle of the metal-coated carbon fiber wire 1, a twisted wire, or a mesh wire assembled in a net shape, or is formed of a copper wire (including a copper alloy wire) or a copper mesh wire. Any one or both of the outer conductors 33 are composed of the metal-coated carbon fiber wire 1.

  In the present invention, the base metal layer 3 is first provided on the carbon fiber 2 because when the carbon fiber is directly plated with copper, the affinity (wetability) between the carbon fiber and copper is poor and the copper is difficult to adhere to the carbon fiber. This is because when the carbon fiber plated with copper is bent, the copper layer peels off. Therefore, in the present invention, first, a kind selected from nickel, nickel alloy, palladium, and cobalt having high affinity with the carbon fiber 2 is applied to the surface of the carbon fiber 2 as the base metal layer 3, and the copper layer 4 is provided thereon. ing.

In the present invention, the ratio of (carbon fiber diameter X) :( underlying metal layer thickness Y) is preferably 1: (0.004-0.071).
If the thickness Y of the base metal layer is less than 0.004 times the diameter X of the carbon fiber, sufficient adhesion of the copper layer (copper plating film) provided on the base metal layer cannot be obtained. This is because if the metal layer thickness ratio is higher than 0.071, the finished metal-coated carbon fiber has poor flexibility and is not preferable.

In the present invention, the ratio of (carbon fiber diameter X) :( copper layer coating thickness Z) is preferably 1: (0.005 to 1.314).
The present invention is a metal-coated carbon fiber electric wire in which a metal-coated carbon fiber wire is used as a conductor and an insulating layer is provided around the conductor. Since the thermal expansion coefficient of the carbon fiber is very small and the resin of the insulating layer provided on the outer periphery of the carbon fiber has a large thermal expansion coefficient, the difference between the thermal expansion coefficients of both is very large. For this reason, in an electric wire using a metal-coated carbon fiber as a conductor, when the electric wire is energized and the electric wire is heated (heated), a phenomenon occurs in which the insulating coating layer is peeled off from the conductor due to a difference in thermal expansion.
The difference in coefficient of thermal expansion is not a problem for an electric wire with a small amount of heat generation, but the difference in coefficient of thermal expansion is a problem for an electric wire with a large amount of heat generation. In the present invention, this difference in coefficient of thermal expansion is solved by adjusting the thickness of the copper layer.
That is, if the thickness of the copper layer is less than 0.005 times the diameter of the carbon fiber, the difference in coefficient of thermal expansion between the carbon fiber and the insulating layer cannot be relaxed, and the metal-coated carbon fiber is increased due to the temperature rise during energization. This causes a problem of peeling between the insulating layer and the insulating layer. On the other hand, when the film thickness ratio of the copper layer is higher than 1.314, the copper layer becomes a relaxation layer for the coefficient of thermal expansion between the carbon fiber and the insulating layer, and the thermal history characteristics are improved. However, as the copper layer becomes thicker, the flexibility becomes poor, and the merit of making the copper layer film thicker is lost.

A metal-coated carbon fiber wire is used as a conductor, and the insulating layer provided thereon can be adopted regardless of the type as long as it is an insulating resin generally used as an electric wire.
The insulating layer is generally formed by extrusion, but can also be formed on the metal-coated carbon fiber by coating.

  In the present invention, a silver layer or a tin layer may be provided on the copper layer provided on the surface of the carbon fiber. The coating of silver or tin is to improve solder wettability, and there is no need to provide it when solder wettability is not a problem. The thickness of the silver or tin layer that improves solder wettability is 0.5 μm or less.

Hereinafter, the present invention will be described in detail with reference to examples.
A metal-coated carbon fiber wire is formed by applying an underlayer (0.2 μm thickness) of nickel, nickel alloy, palladium, or cobalt to carbon fiber by electrolysis or electroless plating, and then forming a copper plating layer (2 μm thickness). Was made.
1,000 metal-coated carbon fiber wires were bundled and twisted to form a conductor, and the conductor was coated with a fluororesin (thickness: 0.3 mm) to obtain a metal-coated carbon fiber electric wire.
In this example, polyacrylonitrile (PAN) carbon fiber having a diameter of 7 μm was used as the carbon fiber.

The plating bath used in this example is as follows.
<Electrolytic nickel plating>
Bath composition (sulfamic acid plating bath)
Nickel sulfamate 320g / L
Nickel chloride 20g / L
Boric acid 30g / L
Plating conditions:
Bath temperature: 50 ° C
Current density: 0.3 A / dm ²
Time: 2min

<Electrolytic nickel-zinc alloy plating>
Bath composition Nickel sulfate 220g / L
Zinc sulfate 3g / L
Ammonium sulfate 15g / L
Plating conditions:
Liquid temperature: 60 ℃
Current density: 0.5 A / dm ²
Time: 3min

<Electrolytic palladium plating>
Bath group:
Diaminopalladium nitrite 9g / L
Ammonium nitrate 110g / L
Sodium nitrite 5g / L
Plating conditions:
Bath temperature: 50 ° C
Current density: 0.3 A / dm ²
Time: 2min

<Electrolytic cobalt plating>
Bath composition:
Cobalt chloride 200g / L
Cobalt carbonate 40g / L
Phosphorous acid 60g / L
Phosphoric acid 50ml / L
Plating conditions:
Bath temperature: 70 ° C
Current density: 0.8 A / dm ²
Time: 2min

<Electrolytic copper plating>
Bath composition (cyan-based copper plating bath)
Copper cyanide 45g / L
Potassium cyanide 100g / L
Potassium carbonate 10g / L
Plating conditions:
Bath temperature: 40 ° C
Current density: 0.4 A / dm ²
Time: 3min

<Electrolytic tin plating>
Bath composition:
Stannous sulfate 45g / L
Sulfuric acid 70g / L
Gelatin 3g / L
Cresol sulfonic acid 100g / L
Plating conditions:
Bath temperature: 25 ° C
Current density: 0.3 A / dm ²
Time: 2min

<Electrolytic silver plating>
Bath composition:
Silver cyanide 40g / L
Potassium cyanide 40g / L
Sodium carbonate 55g / L
Plating conditions:
Bath temperature: 25 ° C
Current density: 0.3 A / dm ²
Time: 3min

Measurement of Plating Thickness Metal-coated carbon fibers were filled with resin, a cross section was taken out with a cross section polisher (CP), and the thickness of the plating layer was measured with a scanning electron microscope (SEM). Regarding the plating thickness, the film thickness at 10 points was measured on the sample, and the average value was defined as the plating thickness.

Evaluation of adhesion of metal film A wire conductor is wound around a φ1 mm metal rod around a twisted wire (before insulation coating) made by twisting metallic carbon fiber fibers, and then a scanning electron microscope and a microscope are used. The surface was observed and the presence or absence of peeling of the plating film on the surface was confirmed. The evaluation was shown in Tables 1 and 2 with ◯ indicating that the sample was not peeled off, Δ when peeling was less than 10%, and x indicating samples where peeling was observed 10% or more.

Production of electric wires, Examples 1 to 29, Comparative Examples 1 to 8, Conventional Examples 1 to 5
The metal-coated carbon fiber electric wire 10 having the configuration shown in FIG. 2 is a bundle of 1000 metal-coated carbon fiber wires, or a twisted wire in which 1000 wires are twisted. It was prepared by coating (0.3 mm thickness). In addition, about how to twist the conductor 11, it describes in Table 1 and Table 2 for every Example.

Production of electric wires, Examples 30 to 34
The metal-coated carbon fiber electric wire 20 having the configuration shown in FIG. 3 is formed by bundling three electric wires 11 created in Examples 1 to 5, and the periphery is covered with a protective insulating layer (polyvinyl alcohol, 0.7 mm thickness) 21. A carbon fiber electric wire (multi-core cable) (hereinafter sometimes referred to as cable A) was produced.

Creation of electric wires, Examples 35-49
As shown in FIG. 4, an inner conductor 31, an insulating resin layer (polyethylene 0.03 mm thickness) 32 around the inner conductor 31, an outer conductor 33, and a protective coating layer (polyethylene terephthalate, 0.23 mm around the outer conductor 33). A metal-coated carbon fiber electric wire (coaxial cable) 30 (hereinafter sometimes referred to as cable B) having a thickness 34 was prepared.
In Examples 35 to 39, the inner conductor was composed of 1000 carbon-coated carbon fiber wires 1 and stranded carbon fiber wires twisted by concentric twisting, and the outer conductor was knitted in a net shape with a copper alloy wire having a diameter of 0.1 mm. It consists of copper mesh wire.
In Examples 40 to 44, the inner conductor is composed of a copper stranded wire prepared by combining seven copper alloy wires having a diameter of 0.1 mm, and the outer conductor is a mesh wire obtained by weaving 1000 metal-coated carbon fiber wires. It is composed.
In Examples 45 to 49, both the inner conductor and the outer conductor are made of metal-coated carbon fiber wires. The inner conductor and the outer conductor are the same as those in the above embodiment (see Table 3).

  The following evaluation was performed with respect to the metal-coated carbon fiber electric wire of the example produced by the above method.

Heat cycle test A heat cycle test was performed on the metal-coated carbon fiber electric wires.
For the test, a sample cut to a length of 10 cm was put into a heat tester, and left in a heating / cooling cycle of −20 ° C./100° C. × 100 (temperature increase 1 h, temperature decrease 2 h) in 30 minutes per cycle, before and after the test. The close contact state with the wire conductor / insulating resin layer was confirmed.
The results are shown in Tables 1 and 2 where the results indicate that no peeling between the resin and the copper layer was observed after the test, that the peeling was less than 10%, and that the peeling was 10% or more. .

Tensile strength measurement Tensile strength was measured according to JIS L 1015 for a stranded wire using a metal-coated carbon fiber wire as a conductor. The cross-sectional area of the metal-coated carbon fiber conductor is calculated by conducting a resin-embedded cross-section observation of an electric wire or cable using a scanning electron microscope (SEM), obtaining four diameters, and taking the average as the sample diameter. Asked.
The evaluation is described in Tables 1 and 2 with respect to the metal-coated carbon fiber electric wire, with 1500 MPa or more being ◯, less than 1500 MPa 900 Pa or more being Δ, and 900 Pa or less being x.
For the electric cables A and B, the results are shown in Table 3, with 950 MPa or more as ◯, less than 950 MPa as 850 MPa or more as Δ, and less than 850 MPa as x.

Flexibility test A flexibility test using a flexibility test apparatus was performed on a stranded wire, an electric wire, and a cable using a metal-coated carbon fiber wire produced by the above method as a conductor. In the test, a twisted wire of a metal-coated carbon fiber bundle and an electric wire using the metal-coated carbon fiber wire were used as samples, and sandwiched with a mandrel, and a load was applied by hanging a 100 g weight at the lower end to suppress the deflection of the wire bundle. The upper end is fixed with a fixing tool, and in this state, the wire bundle is bent 90 degrees to the left and right along the outer periphery of the mandrel, one reciprocation is performed at a rate of 100 times per minute, and the stranded wire is disconnected. The number of times to do was measured. Evaluation is as follows. For metal-coated carbon fiber electric wires, the ones disconnected at 30000 times or more are indicated as “◯”, the ones disconnected at less than 30000 times at 20000 times or more are indicated as Δ, the ones disconnected at less than 20000 times are indicated as “x”, Described. Moreover, about the cable A, what was cut | disconnected by 500,000 times or more was set to (circle), what was cut | disconnected in less than 500,000 times and 30000 times or more is set to (triangle | delta), and what was disconnected in less than 30000 times was set to x. For cable B, the cable disconnected at 100,000 times or more was marked as “◯”, the cable disconnected at less than 100,000 times at 10000 times or more was Δ, the cable disconnected at less than 10000 times was marked as “x”, and listed in Table 3.

Solder test Solder wettability test based on meniscograph method on stranded wire with silver or tin plating on the surface of metal-coated carbon fiber wire with nickel plating and copper plating on carbon fiber. (Lead-free solder, 245 ° C., flux rosin 25%, immersion depth 1 mm, immersion time 10 s) was performed, and the zero cross time was measured. In the evaluation, a case where the zero crossing time was 2.5 s or less was evaluated as “good” when the solder was wet, and a case where the crossing time was less than 2.5 s was evaluated as “poor”. As apparent from Table 4, the solder wettability was good in all examples.

Table 1 shows a metal-coated carbon fiber bundle in which nickel (Ni), nickel alloy (Ni—Zn), palladium (Pd), or cobalt (Co) is used for the base metal layer, and a copper layer is provided on the base metal layer. As a result of various evaluations on the electric wire produced by coating a fluorinated resin on a stranded wire by twisting together with a single fiber bundle, concentric twisting, unilay twisting, collective twisting, and rope twisting (However, the evaluation of the adhesion between the copper film and the carbon fiber is evaluated before coating with the fluororesin).
From Table 1, the conventional examples 1 to 5 in which the copper layer is directly plated without providing the base metal layer have very poor adhesion between the carbon fiber and the copper layer, and the copper film is easily peeled off in the adhesion confirmation test, which is not preferable. It is the result.
On the other hand, in the example using nickel, nickel alloy, palladium, and cobalt as the base metal, the property evaluation results are good when any metal is used as the base metal, and these metals are preferable as the base metal. It was proved. In addition, regarding a single fiber bundle or a stranded wire produced by any twisting method of concentric twisting, unilay twisting, collective twisting, and rope twisting, favorable results are shown in various evaluations. As a result, in the metal-coated carbon fiber electric wire in the present invention, these various twisting methods can be preferably used.

Table 2 shows various evaluation results for Examples prepared by changing the thickness of the nickel layer and the thickness of the copper plating layer using a twisted wire manufactured by concentric twisting using nickel for the base metal layer as a conductor. . Table 2 also shows the ratio of the thicknesses when the carbon fiber diameter is 1.
From this result, if the nickel layer thickness ratio is less than 0.004 with respect to the diameter of the carbon fiber, sufficient adhesion of the copper plating film cannot be obtained, and if the nickel plating thickness is greater than 0.071, the flexibility The result is poor.
As for the thickness of the copper layer, if the copper thickness ratio is less than 0.005, peeling between the insulating resin and the electric wire conductor (metal surface) is likely to occur after the heat cycle test, and if the copper layer is thicker than 1.314, the copper layer is bent. The result is also unfavorable because it is poor in nature.
From this evaluation result, considering the adhesion between the copper film / carbon fiber, the insulating resin coating layer, and the conductor wire, the base metal plating thickness is 0.004 to 0.071 with respect to the diameter of the carbon fiber, copper plating Preferred properties are obtained when the thickness is 0.005 to 1.314 relative to the diameter of the carbon fiber.
In Table 2, metal-coated carbon fiber wires having two or more items evaluated as Δ were judged as comprehensive evaluation Δ, and were designated as Comparative Examples 1-8. However, the metal-coated carbon fiber wires of Comparative Examples 1 to 8 are sufficiently practical depending on the method of use.

Table 3 shows the results of investigating the bendability and tensile strength of an electric wire produced using a metal-coated carbon fiber electric wire with a base metal layer made of nickel. In cable B, the results when used for the inner conductor, the outer conductor, and both the inner and outer conductors are shown.
As a result, the flexibility and tensile strength were satisfactory in any configuration of the cables A and B. Moreover, it was demonstrated that various twisting methods such as single fiber bundles, concentric twisting, unilay twisting, collective twisting, and rope twisting can be preferably used for twisting the metal-coated carbon fiber wire conductor to be used.

  In Examples 50 to 59 shown in Table 4, silver plating or tin plating (0.5 μm thickness or less) was further applied to the surface (on the copper plating layer) of the metal-coated carbon fiber wire produced using nickel as the base metal. The result of having performed various evaluation using the produced strand wire is shown. From this, even when two or more metal film layers are formed, good results in various properties are shown, and furthermore, by forming a silver or tin plating layer on the surface, good solder wettability It was demonstrated to show. Therefore, it was shown that by forming two or more metal layers on the carbon fiber, it is possible to impart solderability and environmental resistance without degrading various characteristics.

  In the present invention, a copper layer having a good conductivity is formed on the surface of a carbon fiber which is excellent in tensile strength and heat resistance and is very light, and if necessary, a silver layer or a tin layer is provided on the copper layer. Therefore, it is possible to provide a metal-coated carbon fiber electric wire that is high in strength and light weight while satisfying conductivity, and is excellent in flexibility and solder wettability.

DESCRIPTION OF SYMBOLS 1 Metal-coated carbon fiber wire 2 Carbon fiber 3 Underlayer 4 Copper layer 5 Tin layer or silver layer 10 Metal-coated carbon fiber electric wire 11 Electric wire conductor 12 Insulating layer 20 Metal-coated carbon fiber electric wire 21 Protective coating layer 30 Metal-coated carbon fiber electric wire 31 Inner conductor 32 Insulating layer 33 Outer conductor 34 Protective coating layer

Claims (9)

  A metal-coated carbon fiber wire in which one or more metal layers are provided on a base metal layer made of one selected from nickel, nickel alloy, palladium, and cobalt provided on the surface of carbon fiber is used as a conductor. A metal-coated carbon fiber electric wire provided with an insulating coating layer around it.   2. The metal according to claim 1, wherein the conductor is one of a metal-coated carbon fiber wire, a bundle of a plurality of bundles, a concentric twist, a unilay twist, a collective twist, or a twisted twisted rope. Coated carbon fiber wire.   An inner conductor, an electric wire in which an outer layer, an outer conductor, and a protective insulating layer are provided in this order on the outer periphery of the inner conductor, and either or both of the inner conductor and the outer conductor are on the surface of the carbon fiber A metal-coated carbon fiber electric wire comprising a metal-coated carbon fiber wire in which one or more metal layers are provided on a base metal layer made of one selected from nickel, nickel alloy, palladium and cobalt.   The said internal conductor is either the single wire of a metal-coated carbon fiber wire, or the bundle wire which bundled two or more, the concentric twist, the unilay twist, the collective twist, or the twisted wire twisted by the rope twist. Metal-coated carbon fiber wire.   The said outer conductor is either the single wire of a metal-coated carbon fiber wire, or the bundle wire which bundled two or more, the concentric twist, the unilay twist, the collective twist, or the twisted wire twisted by the rope twist. Metal-coated carbon fiber wire.   A metal-coated carbon fiber electric wire in which a plurality of the metal-coated carbon fiber electric wires according to claim 1 or 2 are bundled and a protective insulating layer is provided around the bundle.   A metal-coated carbon fiber electric wire in which a plurality of the metal-coated carbon fiber electric wires according to any one of claims 3 to 5 are bundled and a protective insulating layer is provided around the bundle.   The metal-coated carbon fiber electric wire according to any one of claims 1 to 7, wherein the metal layer is a copper layer or a silver layer provided on the copper layer or a tin layer provided on the copper layer. The carbon fiber has a diameter of 3 μm or more and 20 μm or less, and the ratio of the diameter X of the carbon fiber wire to the thickness Y of the base metal layer and the thickness Z of the metal layer is X: Y: Z = 1: (0 .004-0.071): (0.005-1.314)
The metal-coated carbon fiber electric wire according to any one of claims 1 to 8, wherein

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