Copper alloy wire, wire, and cable

Abstract

To provide a copper alloy wire improved in both strength and electrical conductivity.SOLUTION: A copper alloy wire 10 comprises a copper alloy 11 containing indium of 0.3 mass% to 0.65 mass% inclusive, and has 0.2% proof stress of 300 MPa or more, electrical conductivity of 80% IACS or more, and elongation of 7% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a copper alloy wire, a plated wire, and an electric wire and a cable using the same. [Background technology]

[0002] Patent Document 1 (JP 5-311285 A) describes a copper alloy wire containing In and Sn in addition to Cu. Patent Document 2 (JP 2014-159609 A) describes a copper alloy body before wiredrawing, which contains 0.01 atomic % or more of at least one element selected from the group consisting of Ag, In, Mg, and Sn. Patent Document 3 (WO 2014 / 007259 A) describes performing intermediate heat treatment between multiple cold working processes in the production process of a copper alloy material. Patent Document 4 (JP 2015-4118 A) describes performing annealing after drawing and then finish drawing in the production process of a drawn copper wire. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-311285 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-159609 [Patent Document 3] International Publication No. 2014 / 007259 [Patent Document 4] Japanese Patent Application Laid-Open No. 2015-4118 Summary of the Invention [Problem to be solved by the invention]

[0004] Metal wires made of copper alloys are used in a variety of applications. For example, in electric wires and cables used as internal wiring components in electronic devices, industrial robots, automobiles, etc., metal wires made of copper alloys are used as conductors. For metal wires used in such applications, improved strength and electrical conductivity are required to improve the flex life and transmission characteristics of the electric wires and cables.

[0005] An object of the present invention is to provide a technique for improving both the strength and the conductivity of a metal wire. [Means for solving the problem]

[0006] A copper alloy wire according to one embodiment is a copper alloy wire made of a copper alloy containing 0.3% by mass or more and 0.65% by mass or less of indium. The copper alloy wire has a 0.2% yield strength of 300 MPa or more, a conductivity of 80% IACS or more, and an elongation of 7% or more.

[0007] For example, it is preferable that the copper alloy contains 0.02 mass % or more and less than 0.1 mass % of tin, and the total content of the indium and the tin is 0.65 mass % or less.

[0008] Another embodiment of the electric wire includes a conductor made of a copper alloy wire and an insulator covering the conductor. The copper alloy wire is made of a copper alloy containing 0.3% by mass to 0.65% by mass of indium. The copper alloy wire has a 0.2% yield strength of 300 MPa or more, a conductivity of 80% IACS or more, and an elongation of 7% or more.

[0009] For example, it is preferable that the copper alloy in the electric wire contains 0.02 mass % or more and less than 0.1 mass % of tin, and the total content of the indium and the tin is 0.65 mass % or less.

[0010] For example, the conductor is preferably made of a plurality of copper alloy wires twisted together.

[0011] Another embodiment of the plated wire includes a copper alloy wire and a plating layer provided around the copper alloy wire, and the copper alloy wire is made of a copper alloy containing 0.3 mass % to 0.65 mass % indium, and has a 0.2% yield strength of 300 MPa or more, a conductivity of 80% IACS or more, and an elongation of 7% or more.

[0012] Another embodiment of the cable includes a plurality of core wires each having a conductor made of a copper alloy wire and an insulator covering the conductor, and a sheath covering the plurality of core wires together. The copper alloy wire contains 0.3% by mass or more and 0.65% by mass or less of indium. The copper alloy wire has a 0.2% yield strength of 300 MPa or more, a conductivity of 80% IACS or more, and an elongation of 7% or more.

[0013] For example, it is preferable that the copper alloy in the cable contains 0.02 mass % or more and less than 0.1 mass % of tin, and the total content of the indium and the tin is 0.65 mass % or less. [Effects of the Invention]

[0014] According to the representative embodiment of the present invention, it is possible to improve both the strength and the conductivity of the metal wire. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective cross-sectional view of a metal wire according to an embodiment of the present invention; [Figure 2] 2 is a flow chart showing an example of a manufacturing process of the metal wire shown in FIG. [Figure 3] FIG. 2 is a cross-sectional view of a cable including the metal wire shown in FIG. [Figure 4] 4 is a cross-sectional view of one of a plurality of electric wires included in the cable shown in FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, a metal wire made of a copper alloy and having a wire diameter (outer diameter) of 100 μm or less will be referred to as a copper alloy wire. Furthermore, a wire before being drawn into a copper alloy wire will be referred to as a roughly drawn wire. Furthermore, a copper alloy wire (metal wire) having a plating layer around it will be referred to as a plated wire.

[0017] In the following description, an index called "IACS (International Annealed Copper Standard)" is used as an evaluation index for electrical conductivity. The electrical conductivity using IACS is calculated based on the volume resistivity of annealed standard soft copper (volume resistivity: 1.7241 × 10 -2 The electrical conductivity of 100% IACS is defined as the electrical conductivity of annealed standard soft copper, and the percentage of this relative to the conductivity of annealed standard soft copper is expressed as "xx% IACS." The electrical conductivity described below is calculated based on the results of measuring the electrical resistance and diameter of a test piece in accordance with the test method for electrical copper wire specified in the Japanese Industrial Standard (JIS C 3002:1992).

[0018] In the following description, when the "elongation" of a metal wire or plated wire is described, a tensile test of a test piece is conducted in accordance with the test method for electrical copper wire specified in the Japanese Industrial Standard (JIS C 3002:1992), and the value calculated from the measurement results is referred to as "elongation." Furthermore, in the following description, when the "0.2% yield strength" of a metal wire or plated wire is described, a tensile test of a test piece is conducted in accordance with the tensile test method for metallic materials specified in the Japanese Industrial Standard (JIS Z 2241:2011), and the value calculated from the measurement results is referred to as "0.2% yield strength."

[0019] <New findings discovered by the present inventors> For example, electric wires and cables are used as internal wiring components wired inside industrial robots installed in factories, etc. Electric wires and cables used for such applications are required to have improved flex life and transmission characteristics. In response to this, the inventors discovered that the problems of improving the flex life and transmission characteristics of electric wires and cables can be solved by improving the 0.2% yield strength, which is one of the strength indicators of metal wires and plated wires used as conductors of electric wires and cables, and also improving the electrical conductivity, which is in a trade-off relationship with improving the 0.2% yield strength, and thus completed the present invention.

[0020] <Metal wire structure> Fig. 1 is a perspective cross-sectional view of a metal wire according to this embodiment. The copper alloy wire 10 shown in Fig. 1 is a copper alloy wire made of a copper alloy 11, which contains 0.3 mass % or more and 0.65 mass % or less of indium (In). The copper alloy 11 contains inevitable impurities as the remainder. The copper alloy wire 10 has a 0.2% yield strength of 300 MPa or more (preferably, 300 MPa or more and 350 MPa or less), a conductivity of 80% IACS or more (preferably, 80% IACS or more and 90% IACS or less), and an elongation of 7% or more (preferably, 7% or more and 18% or less).

[0021] Examples of the unavoidable impurities contained in the copper alloy 11 include aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), chromium (Cr), iron (Fe), nickel (Ni), arsenic (As), selenium (Se), silver (Ag), antimony (Sb), lead (Pb), and bismuth (Bi). The unavoidable impurities contained in the copper alloy 11 are contained in a range of, for example, 20 ppm by mass to 30 ppm by mass.

[0022] The copper alloy wire 10 having the above-described copper alloy 11 can achieve both high levels of 0.2% proof stress and electrical conductivity. As will be described in detail later as an example, the inventors of the present application have confirmed that a copper alloy wire 10 having a copper alloy 11 containing 0.3 mass % or more and 0.65 mass % or less of indium (In), with the remainder consisting of copper (Cu) and unavoidable impurities, has electrical conductivity of 80% IACS or more and a 0.2% proof stress of 300 MPa or more.

[0023] Conductive wires that transmit electricity (hereinafter simply referred to as electric wires) are components that constitute power transmission paths or electric signal transmission paths, and are widely used in various fields. Conductive materials such as various types of pure metals, alloys, and composite materials are used as conductors in electric wires. In this embodiment, a copper alloy wire 10 made of a copper alloy 11 having high conductivity will be described as the conductor of the electric wire.

[0024] Copper wires used as conductors in electric wires are used in various fields as described above, but depending on the field of use, copper wires with small wire diameters may be required. For example, in electronic devices such as portable terminals, electric wires with conductors made of copper wires are used as internal wiring components. In this case, the diameter of a single copper wire may be required to be 100 μm or less. Furthermore, in the case of probe cables used in the medical field, they may be used for insertion into a patient's body, and copper wires with even smaller diameters are required. In this embodiment, a copper alloy wire 10 with a wire diameter 10D of 80 μm will be described as an example of an ultrafine wire.

[0025] The 0.2% proof stress of the copper alloy wire 10 made of the copper alloy 11 can be improved by inducing strain in the copper alloy 11. Methods for inducing strain in the copper alloy 11 include increasing the content of metal elements other than copper contained in the copper alloy 11, and performing wire drawing. However, when strain is generated in the copper alloy wire 10 by these methods, the resistivity of the copper alloy 11 as a conductive member increases, and therefore the conductivity of the copper alloy wire 10 decreases. In other words, there is a trade-off between increasing the 0.2% proof stress of the copper alloy wire 10 and increasing the conductivity of the copper alloy wire 10.

[0026] Therefore, in order to find a configuration that improves the electrical conductivity and 0.2% proof stress of a solid-solution strengthened copper alloy 11, the inventors focused on the effect of several types of metal elements on the decrease in electrical conductivity of the copper alloy 11 when solid-solubilized in the copper alloy 11 and the degree to which they contribute to strengthening the 0.2% proof stress. That is, the degree of contribution to improving the 0.2% proof stress of the copper alloy wire 10 varies depending on the type of metal element, and the 0.2% proof stress increases proportionally as the content of the element solid-solubilized in copper increases. Tin (Sn) and indium (In) are effective additive elements because they have a greater effect on increasing the 0.2% proof stress when solid-solubilized in copper than metals such as aluminum (Al), nickel (Ni), or magnesium (Mg).

[0027] On the other hand, the degree of influence on the decrease in conductivity varies greatly depending on the type of metal element. Specifically, compared to metals such as nickel (Ni), tin (Sn), and aluminum (Al), silver (Ag), indium (In), and magnesium (Mg) can suppress the decrease in conductivity even when their concentration in copper is high. For example, when the concentration (mass concentration) of the above metal elements dissolved in oxygen-free copper is 900 ppm, the conductivity of tin (Sn) decreases to about 92% of that of pure copper (taken as 100% (percentage)), while the conductivity of indium (In) decreases to only about 98%. Furthermore, the conductivity of silver (Ag) decreases to only about 99% of that of pure copper (taken as 100% (percentage)).

[0028] From the above-mentioned characteristics, the copper alloy 11 obtained by dissolving indium in copper has high levels of electrical conductivity and 0.2% proof stress. In the case of a copper alloy in which silver (Ag) is dissolved in copper, an even higher electrical conductivity than the copper alloy wire 10 of the present embodiment can be obtained. However, at the same concentration, silver has a smaller effect of increasing the 0.2% proof stress than indium, and therefore, increasing the silver content increases the raw material cost of the copper alloy wire 10, so it is preferable to dissolve indium.

[0029] Furthermore, it is preferable that the oxygen content in the copper alloy is small in order to improve the 0.2% proof stress of the copper alloy 11. In the present embodiment, the oxygen content in the copper alloy 11 is 0.002% by mass or less. If the oxygen content in the copper alloy 11 is 0.002% by mass or less, it is possible to prevent the 0.2% proof stress of the copper alloy 11 from decreasing due to oxygen.

[0030] 1, the copper alloy wire 10 may be modified such that the copper alloy 11 contains 0.3 mass% or more and less than 0.65 mass% indium (In) and 0.02 mass% or more and less than 0.1 mass% tin (Sn), with the remainder being copper (Cu) and unavoidable impurities. However, the total content of indium and tin contained in the copper alloy 11 is 0.65 mass% or less.

[0031] In the case of the modified copper alloy wire 10, since the copper alloy 11 contains tin in a solid solution, the electrical conductivity is relatively low compared to the above-mentioned copper alloy wire 10 that does not contain tin. However, by making the tin content less than 0.1 mass % and adding 0.3 mass % or more of indium, it is possible to maintain an electrical conductivity of 80% IACS or more. However, it is desirable that the total content of indium and tin contained in the copper alloy 11 is 0.65 mass % or less. In this way, in the case of the modified copper alloy wire 10, by making tin in a solid solution at a predetermined content, it is possible to maintain an electrical conductivity of 80% IACS or more and reduce the raw material cost of the copper alloy wire 10.

[0032] <Metal Wire Manufacturing Method> Next, a method for manufacturing the copper alloy wire 10 shown in Fig. 1 will be described. The above-mentioned copper alloy wire 10 may or may not contain tin in the copper alloy, but the manufacturing method is the same. Fig. 2 is a flow chart showing an example of a manufacturing process for the metal wire shown in Fig. 1.

[0033] In the following, a method for manufacturing a metal wire will be described, in which a wire rod having a certain diameter (for example, about 8 mm to 12 mm) is manufactured by a continuous casting and rolling method, and then the wire rod is drawn to manufacture a metal wire. The continuous casting and rolling method may be, for example, a continuous casting and rolling method called the SCR system (Southwire Continuous Rod system).

[0034] First, in the raw material preparation step shown in FIG. 2, a raw material is prepared. The raw material is a metal containing copper as a main component. In addition to copper, the raw material may contain impurity elements that are inevitably mixed in, as described above. The raw material also contains additive elements including indium. In the method for manufacturing a metal wire described as a modified example of the copper alloy wire 10 shown in FIG. 1, the additive elements are indium and tin. These additive elements are added to the raw material containing copper as a main component within a range that satisfies the above-mentioned content conditions.

[0035] Next, in the melting process shown in Fig. 2, the raw materials are melted in a melting furnace (not shown). The melting furnace is a heating furnace that can continuously melt the raw materials, and the molten copper melted in the melting furnace is transferred sequentially to a heat-retaining furnace (not shown).

[0036] Next, in the casting process shown in FIG. 2, the molten copper in the heat-retaining furnace is poured into a mold (not shown) and then cooled to solidify. The solidified casting is removed from the mold and sequentially sent to a rolling mill. The melting process to the casting process shown in FIG. 2 are carried out in an inert gas atmosphere (e.g., a nitrogen atmosphere). There is almost no oxygen in the inert gas atmosphere, and at least the oxygen concentration (volume concentration) is 10 ppm or less. In this way, by manufacturing the wire rod in an inert gas atmosphere with an extremely low oxygen concentration, it is possible to suppress the inclusion of oxygen in the copper during the casting process.

[0037] Next, in the rolling step shown in Fig. 2, the cast product is rolled to form a wire rod having a wire diameter of about 8 mm to 12 mm. In the rolling step, the rolling treatment may be performed multiple times. Note that if the cast product obtained in the casting step is used as a wire rod as is, this rolling step can be omitted. Furthermore, the wire rod may be subjected to a surface cleaning treatment such as oxide removal after the rolling step.

[0038] Next, in the winding process shown in Fig. 2, the wire is wound by a winding device (not shown) to obtain a roll of wire rod. The wire rod wound by the winding device has a 0.2% yield strength of about 50 MPa to 150 MPa and an electrical conductivity of more than 85% IACS and about 95% IACS or less.

[0039] Next, in the wiredrawing process shown in FIG. 2, the roughly drawn wire is drawn until the wire diameter is 100 μm or less (for example, about 50 μm to 80 μm) to obtain a drawn wire material of a hard material. The wiredrawing process is carried out at room temperature (for example, 25°C), so-called cold working. In the wiredrawing process, the roughly drawn wire is elongated in the extension direction, but the wiredrawing process is divided into multiple steps (a first wiredrawing process and a second wiredrawing process), and a heat treatment process (sometimes called an annealing process) is performed between the wiredrawing processes to apply heat treatment to the drawn wire material during the wiredrawing process. Note that the first wiredrawing process is preferably carried out by drawing the roughly drawn wire (for example, about 8 mm to 12 mm in diameter) to the desired wire diameter (for example, 0.5 mm to 3.0 mm in diameter) in a single wiredrawing process.

[0040] During wiredrawing, strain occurs in the metal wire, which increases the 0.2% yield strength of the metal wire, but decreases the electrical conductivity of the metal wire. Heat treatment during wiredrawing reduces strain in the metal wire. Therefore, the 0.2% yield strength of the heat-treated metal wire decreases, but its electrical conductivity increases. According to the inventors' studies, it has been found that the 0.2% yield strength and electrical conductivity of the final semi-hard metal wire (copper alloy wire 10) can be maintained at a high level by performing a heat treatment process during the wiredrawing process (between the first wiredrawing process and the second wiredrawing process) so as to satisfy the following conditions. The semi-hard copper alloy wire referred to here is a metal wire with an elongation of 7% or more and 18% or less.

[0041] Assuming that the 0.2% proof stress of the metal wire before heat treatment (after the wiredrawing process immediately before heat treatment) is A, the 0.2% proof stress of the metal wire after heat treatment (immediately after heat treatment) is B, and C = B / A, heat treatment is performed so that the 0.2% proof stress ratio C is 0.5 to 0.8. Furthermore, assuming that the elongation of the metal wire before heat treatment (after the wiredrawing process immediately before heat treatment) is D, the elongation of the metal wire after heat treatment (immediately after heat treatment) is E, and F = E / D, heat treatment is performed so that the elongation ratio F is 10 to 50. Note that, as shown in FIG. 2, because further wiredrawing is performed after the heat treatment, it is preferable that the heat treatment be performed so that the electrical conductivity of the metal wire immediately after the heat treatment is 86% IACS or higher (preferably 88% IACS or higher). Furthermore, it is preferable that the 0.2% proof stress of the metal wire immediately after the heat treatment is 60 MPa to 200 MPa, and the elongation of the metal wire immediately after the heat treatment is 20% to 40%. This allows the electrical conductivity to be 80% IACS or higher after the wire drawing process (second wire drawing process) that follows the heat treatment process. Note that the heat treatment process described above is preferably performed at a temperature of 400°C or higher and 900°C or lower.

[0042] 2 illustrates an embodiment in which a rough wire is drawn to a desired wire diameter (for example, a wire diameter of 0.5 mm or more and 3.0 mm or less) in a wiredrawing process (first wiredrawing process), the drawn wire is then subjected to a heat treatment process under the conditions described above, and the drawn wire is then drawn to a desired wire diameter (for example, a wire diameter of 0.1 mm or less) in a wiredrawing process (second wiredrawing process). However, various modifications are also applicable. For example, the second wiredrawing process may be divided into multiple wiredrawing processes, and the drawn wire may be drawn stepwise to the desired wire diameter in each of the multiple wiredrawing processes. By drawing the drawn wire stepwise through multiple wiredrawing processes in the second wiredrawing process, the hard drawn wire described above can be obtained more reliably than when the second wiredrawing process is composed of a single wiredrawing process. In addition, when the second wiredrawing process is composed of multiple wiredrawing processes, the above-mentioned heat treatment process may be performed between the multiple wiredrawing processes as needed. The hard drawn wire material referred to here is a metal wire with an elongation of 0.5% to 3% and a wire diameter of 100 μm or less.

[0043] Next, the hard wire drawn material having a wire diameter of 100 μm or less obtained in the wiredrawing process is subjected to a semi-hardening treatment. By subjecting the hard wire drawn material to the semi-hardening treatment, a metal wire (copper alloy wire 10) in a semi-hard state is obtained. For the semi-hardening treatment, it is preferable to heat the hard wire drawn material obtained in the wiredrawing process under heating conditions such as a heating temperature of 520°C to 580°C and a heating time of 0.3 seconds to 0.8 seconds. This results in a copper alloy wire 10 having a 0.2% proof stress of 300 MPa to 350 MPa, an electrical conductivity of 80% IACS to 90% IACS, an elongation of 7% to 18%, and a wire diameter of 100 μm or less.

[0044] <Alloy composition and property evaluation> Next, a description will be given of the results of an experiment on the relationship between the alloy composition and properties of the copper alloy wire 10 shown in Fig. 1. Table 1 shows the relationship between the alloy composition and properties of the metal wire.

[0045] [Table 1]

[0046] In Table 1, Samples Nos. 1 to 3 are examples that meet the requirements for the copper alloy wire 10, and Samples Nos. 4 to 7 are comparative examples that do not meet the requirements for the copper alloy wire 10. Each of Samples Nos. 1 to 7 was manufactured through the manufacturing process described with reference to FIG. 2. In Table 1, the samples used for the 0.2% proof stress test and elongation test were metal wires processed to have a wire diameter of approximately 80 μm. The elongation was measured at a tension speed of 50 mm / min and a gauge length of 250 mm. The 0.2% proof stress was measured by a tensile test in accordance with JIS Z2241. More specifically, the tensile test (offset method, gauge length: 250 mm, tension speed: 50 m / min) was performed to measure the 0.2% proof stress. The cross-sectional area of ​​the sample was calculated as the area of ​​a perfect circle from the wire diameter measured to 1 / 1000 mm using a micrometer. The elongation value is the total elongation at break (the sum of the elastic elongation and plastic elongation of the extensometer) and is expressed as a percentage of the extensometer gauge length. Although not shown in Table 1, each of Samples Nos. 1 to 7 was prepared in an environment where oxygen was unlikely to be mixed in, and the oxygen content of the copper alloy of each sample was 0.002 mass% or less.

[0047] In Table 1, the flex life was measured by hanging a 20g weight from the sample and bending it 90 degrees left and right around a jig with a bending radius of 5mm as a fulcrum until it broke. Each 90 degree bend was counted as one cycle.

[0048] As can be seen from samples Nos. 1 and 2 in Table 1, when only indium is added to a copper alloy, a good flex life (flexing times of 3,000 or more) can be obtained by making the indium content 0.30 mass% or more, the 0.2% yield strength of the sample 300 MPa or more, and the elongation 7% or more.

[0049] Furthermore, as can be seen from a comparison of Samples Nos. 3 to 7 in Table 1, when indium and tin are added to a copper alloy, the indium content is 0.30 mass% or more and less than 0.65 mass%, the tin content is 0.02 mass% or more and less than 0.1 mass%, and the 0.2% yield strength of the sample is 300 MPa or more and the elongation is 7% or more, thereby achieving a good flex life (for example, 3,000 or more flex cycles).

[0050] <Application examples of copper alloy wire> Next, an application example of the copper alloy wire 10 shown in Fig. 1 will be described. Fig. 3 is a cross-sectional view of a cable including the copper alloy wire 10 shown in Fig. 1. Fig. 4 is a cross-sectional view of one of the electric wires included in the cable shown in Fig. 3.

[0051] The cable 60 shown in FIG. 3 includes multiple electric wires (core wires) 70 and a sheath 61 that collectively covers the multiple electric wires 70. A filler (not shown) is disposed around each of the multiple electric wires 70, separating the multiple electric wires 70 from one another. The filler is made of, for example, a linear member formed of fiber or resin. The sheath 61 is made of, for example, a resin composition or a fluororesin composition whose main component (base resin) is a resin such as chlorinated polyethylene or polyvinyl chloride. The multiple electric wires 70 may be in contact with one another. The cable 60 is used, for example, as an internal wiring material for portable electronic devices such as smartphones, industrial robots installed in factories, or automobiles. The cable 60 includes multiple electric wires 70, each of which has a small outer diameter. For example, in the example shown in FIGS. 3 and 4, the outer diameter of the electric wire 70 is, for example, approximately 0.86 mm (860 μm).

[0052] As shown in Fig. 4, the electric wire 70 has a central conductor 71 made of a plurality of copper alloy wires 10 twisted together, and an insulator 72 covering the central conductor 71. Each of the plurality of copper alloy wires 10 constituting the central conductor 71 is made of the copper alloy 11 described with reference to Fig. 1. That is, the copper alloy 11 constituting this copper alloy wire 10 contains 0.3 mass % to 0.65 mass % indium. Each of the plurality of copper alloy wires 10 has a wire diameter of, for example, 0.08 mm (80 µm). The insulator 72 is made of, for example, a resin such as polyethylene or polypropylene, or a fluororesin.

[0053] In this way, the electric wire 70 using a plurality of copper alloy wires 10 and the cable 60 using the same can improve the transmission characteristics of electric signals or power within portable electronic devices. Alternatively, the electric wire 70 using a large number of ultra-fine copper alloy wires 10 and the cable 60 using the same can have a small wire diameter, which allows the size of the housing of portable electronic devices to be reduced and industrial robots and the like to be miniaturized.

[0054] While Fig. 4 exemplarily illustrates the electric wire 70, there are various modifications to the electric wire to which the copper alloy wire 10 shown in Fig. 1 is applied. For example, the present invention can be applied to an electric wire comprising a conductor made of a single copper alloy wire 10 and an insulator covering the conductor. Furthermore, Figs. 3 and 4 exemplify the central conductor 71 of the electric wire 70 as being formed by twisting together a plurality of copper alloy wires 10, but the present invention is not limited to this, and the central conductor 71 may be formed of a plated wire, as described below.

[0055] <Plated wire> The plated wire is constructed by having a plating layer on the periphery (outer surface) of the copper alloy wire 10 shown in Fig. 1. The plated wire has a 0.2% yield strength of 300 MPa or more, a conductivity of 80% IACS or more, and an elongation of 7% or more. That is, when the plated wire is provided with a plating layer on the periphery of the copper alloy wire shown in Fig. 1, the plated wire has a 0.2% yield strength of 300 MPa or more (preferably, 300 MPa or more and 340 MPa or less), a conductivity of 80% IACS or more (preferably, 80% IACS or more and 89% IACS or less), and an elongation of 7% or more (preferably, 7% or more and 18% or less). The plated wire is a semi-hard wire.

[0056] As described above, the copper alloy wire is made of a copper alloy containing 0.3 mass% or more and 0.65 mass% or less of indium (In). In particular, the copper alloy wire is preferably made of a copper alloy containing 0.3 mass% or more and 0.65 mass% or less of indium (In), with the balance being copper (Cu) and unavoidable impurities. Alternatively, the copper alloy wire may be made of a copper alloy containing 0.3 mass% or more and less than 0.65 mass% of indium (In) and 0.02 mass% or more and less than 0.1 mass% of tin (Sn), with the balance being copper (Cu) and unavoidable impurities. In this case, the total content of indium and tin contained in the copper alloy is 0.65 mass% or less.

[0057] The plating layer is provided around the copper alloy wire so as to contact the surface of the copper alloy wire. The thickness of the plating layer is, for example, 0.1 μm or more and 1.5 μm or less. The plating layer is made of, for example, tin (Sn), silver (Ag), nickel (Ni), etc.

[0058] <Method of manufacturing plated wire> The plated wire is obtained by forming a plating layer on a copper alloy wire obtained by the copper alloy wire manufacturing method shown in FIG. 2. The copper alloy wire before the plating layer is formed is a semi-hard metal wire with a 0.2% proof stress of 300 MPa or more and a conductivity of 80% IACS or more. The copper alloy wire is immersed in a plating tank containing a molten plating material (e.g., Sn) at a predetermined temperature (e.g., 250°C to 300°C). This applies a hot-dip coating to the entire outer surface of the copper alloy wire. The copper alloy wire coated with the hot-dip coating is then passed through a plating die to adjust the thickness of the hot-dip coating applied to the surface of the copper alloy wire, thereby forming a plating layer with a predetermined thickness. In particular, the hot-dip coating is preferably applied to the surface of the copper alloy wire at a linear speed of 100 m / min or more for an immersion time in the hot-dip coating of 0.1 to 1.0 seconds. The copper alloy wire on which the plating layer is formed in this manner maintains a semi-hard state and has an elongation of 7 to 18%.

[0059] <Characteristics of plated wire> Next, the results of experiments on the properties of plated wires will be described. Tables 2 and 3 show the relationship between the alloy composition of the copper alloy wires that make up the plated wires and the properties of the plated wires.

[0060] [Table 2]

[0061] [Table 3]

[0062] In Tables 2 and 3, Samples Nos. 8, 13, and 14 are examples that meet the above-mentioned conditions for plated wire, and Samples Nos. 9 to 12, and 15 to 16 are comparative examples that do not meet the above-mentioned conditions for plated wire. Each of Samples Nos. 8 to 12 shown in Table 2 and Samples Nos. 13 to 16 shown in Table 3 is a copper alloy wire manufactured through the manufacturing process described with reference to Fig. 2, with a plating layer formed around it. Specifically, the copper alloy wire manufactured through the manufacturing process described with reference to Fig. 2 was immersed in a plating tank containing molten Sn (temperature: 250°C or higher and 300°C or lower), and then the copper alloy wire with the hot-dip coating applied thereto was passed through a plating die, thereby adjusting the thickness of the hot-dip coating applied to the surface of the copper alloy wire and forming a plating layer having a predetermined thickness. In Tables 2 and 3, the samples used for the 0.2% proof stress test and elongation test of plated wire were copper alloy wires processed to a wire diameter of approximately 80 μm and then coated with a plating layer (thickness: approximately 0.5 μm). The copper alloy wires used in Samples 8 to 16 contained indium (In) and tin (Sn) in the amounts shown in Tables 2 and 3, with the remainder being copper (Cu) and unavoidable impurities. The elongation was measured at a tension speed of 50 mm / min and a gauge length of 250 mm. The 0.2% proof stress was measured by a tensile test in accordance with JIS Z2241. More specifically, the 0.2% proof stress was measured by the above-mentioned tensile test (offset method, gauge length: 250 mm, tension speed: 50 m / min). The cross-sectional area of ​​the sample was calculated as the area of ​​a perfect circle from the wire diameter measured to 1 / 1000 mm using a micrometer. The elongation value is the total elongation at break (the sum of the elastic elongation and plastic elongation of the extensometer) and is expressed as a percentage of the extensometer gauge length. Although not shown in Tables 2 and 3, each of Samples Nos. 8 to 16 was prepared in an environment where oxygen was unlikely to be mixed in, and the oxygen content of the copper alloy of each sample was 0.002 mass% or less.

[0063] In Tables 2 and 3, the flex life was measured by hanging a 20g weight from the sample and bending it 90 degrees left and right around a jig with a bending radius of 5mm as a fulcrum until it broke. Each 90 degree bend was counted as one cycle.

[0064] As can be seen from Samples 8, 13, and 14 in Tables 2 and 3, the plated wires have a plating layer provided around a copper alloy wire made of a copper alloy with an indium content of 0.30% by mass or more, a 0.2% proof stress of 300 MPa or more, and an elongation of 7% or more, thereby achieving a good flex life (3,000 or more flexes). In particular, the plated wires have a plating layer provided around a copper alloy wire made of a copper alloy with an indium content of 0.30% by mass or more but less than 0.65% by mass, the balance being copper and unavoidable impurities, or a copper alloy wire with an indium content of 0.30% by mass or more but less than 0.65% by mass, a tin content of 0.02% by mass or more but less than 0.1% by mass, the balance being copper and unavoidable impurities, and a 0.2% proof stress of 300 MPa or more and an elongation of 7% or more, thereby achieving a good flex life (e.g., 3,000 or more flexes).

[0065] <Application examples of plated wire> As described above, the plated wire can be used as the central conductor of the electric wire or cable shown in Figures 3 and 4. Specifically, the electric wire has a central conductor made of multiple plated wires twisted together and an insulator covering the central conductor. Also, the electric wire may be surrounded by a shielding layer or sheath to form a cable.

[0066] The present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit and scope of the present invention.

[0067] The above embodiment includes the following aspects.

[0068] [Appendix 1] (a) preparing a raw material containing copper and an additive element other than copper; (b) melting the raw material and then casting it to form a wire rod; (c) drawing the wire into a metal wire; (d) after the step (c), a step of subjecting the drawn metal wire to a heat treatment; (e) after the step (d), further drawing the heat-treated metal wire to form a copper alloy wire having an outer diameter of 0.1 mm or less; (f) after the step (e), a step of subjecting the copper alloy wire to semi-hardening treatment; Including, The method for manufacturing a copper alloy wire, wherein the roughly drawn wire is made of a copper alloy containing 0.3 mass % or more and 0.65 mass % or less of indium.

[0069] [Appendix 2] In Appendix 1, The copper alloy contains 0.02 mass% or more and less than 0.1 mass% tin.

[0070] [Appendix 3] In Appendix 1 or 2, In the step (d), where A denotes the 0.2% yield strength of the metal wire that has been drawn after the step (c), B denotes the 0.2% yield strength of the metal wire that has been heat-treated after the step (d), and the ratio of the 0.2% yield strengths is C=B / A, the heat treatment is performed so that the value of C is 0.5 or more and 0.8 or less; a heat treatment is performed so that the value of F becomes 10 or more and 50 or less, where D is the elongation of the metal wire that has been drawn after the step (c), E is the 0.2% yield strength of the metal wire that has been heat treated after the step (d), and F is the elongation ratio F / D.

[0071] [Appendix 4] In Appendix 3, in the method for manufacturing a copper alloy wire, in the step (d), a heat treatment is performed so that the conductivity of the metal wire immediately after the heat treatment in the step (d) is 86% IACS or more. [Industrial Applicability]

[0072] The present invention can be used in copper alloy wires used as conductors in cables (e.g., micro-coaxial cables) used in internal wiring components of small electronic devices (e.g., digital cameras, surveillance cameras, personal computers, smartphones, etc.), flexible cables (e.g., endoscope cables, probe cables, etc.) used in industrial robots and medical devices (e.g., gastroscopes, ultrasound diagnostic devices, etc.), and automotive cables. [Explanation of symbols]

[0073] 10 Copper alloy wire 10D wire diameter 11 Copper alloys 60 Cable 61,74 Sheath (insulator) 70 Electric wires (core wires, coaxial cables) 71 Center conductor 72 Insulators 73 Outer conductor

Claims

1. A copper alloy containing 0.3% by mass or more and 0.65% by mass or less of indium and 0.02% by mass or more and less than 0.1% by mass of tin, wherein the total content of said indium and said tin is 0.65% by mass or less, and the remainder is copper and unavoidable impurities; A copper alloy wire having a 0.2% yield strength of 300 MPa or more, a conductivity of 80% IACS or more, and an elongation of 7% or more.

2. A device comprising: a conductor; and an insulator covering the conductor; the conductor is a copper alloy wire containing 0.3 mass % or more and 0.65 mass % or less of indium and 0.02 mass % or more and less than 0.1 mass % of tin, the total content of the indium and the tin being 0.65 mass % or less, and the remainder being a copper alloy containing copper and unavoidable impurities; The copper alloy wire has a 0.2% yield strength of 300 MPa or more, a conductivity of 80% IACS or more, and an elongation of 7% or more.

3. In the electric wire according to claim 2, The conductor is an electric wire formed by twisting together a plurality of the copper alloy wires.

4. A cable having a plurality of core wires each made of an electric wire with a conductor covered with an insulator, and a sheath covering the plurality of core wires together, the conductor is a copper alloy wire containing 0.3 mass % or more and 0.65 mass % or less of indium and 0.02 mass % or more and less than 0.1 mass % of tin, the total content of the indium and the tin being 0.65 mass % or less, and the remainder being copper and unavoidable impurities; The copper alloy wire has a 0.2% yield strength of 300 MPa or more, a conductivity of 80% IACS or more, and an elongation of 7% or more.

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