JP7574633B2 - Copper alloy wire, plated wire, electric wire, and cable - Google Patents

Description

The present invention relates to copper alloy wire, plated wire, and electric wire and cable using the same.

Patent Document 1 (JP Patent Publication No. 5-311285) describes a copper alloy wire containing In and Sn in addition to Cu. Patent Document 2 (JP Patent Publication No. 2014-159609) describes a copper alloy body containing 0.01 atomic % or more of at least one element selected from the group consisting of Ag, In, Mg, and Sn as a copper alloy body before wire drawing. Patent Document 3 (WO 2014/007259) describes performing intermediate heat treatment between multiple cold working processes in the manufacturing process of a copper alloy material. Patent Document 4 (JP Patent Publication No. 2015-4118) describes performing annealing after drawing and then finish drawing in the manufacturing process of drawn copper wire.

Japanese Patent Application Publication No. 5-311285 JP 2014-159609 A International Publication No. 2014/007259 JP 2015-4118 A

Metal wires made of copper alloys are used for a variety of purposes. For example, there is a demand for thinner metal wires that make up the conductors and cables used in the wiring components of electronic devices. In such applications, there is a demand for thinner metal wires with improved strength and electrical conductivity.

The objective of the present invention is to provide a technology that improves both the strength and electrical conductivity of metal wires.

The copper alloy wire in one embodiment is a copper alloy wire made of a copper alloy, and the copper alloy contains 0.3% by mass or more and 0.45% by mass or less of indium. The tensile strength of the copper alloy wire is 800 MPa or more, and the electrical conductivity is 80% IACS or more.

For example, the copper alloy contains 0.02% by mass or more and less than 0.1% by mass of tin, and the total content of the indium and the tin is 0.45% by mass or less.

Another embodiment of the electric wire comprises a conductor made of a copper alloy wire and an insulator that covers the conductor. The copper alloy wire is made of a copper alloy containing 0.3% to 0.45% by mass of indium. The tensile strength of the copper alloy wire is 800 MPa or more, and the electrical conductivity of the copper alloy wire is 80% IACS or more.

For example, the copper alloy in the electric wire contains 0.02% by mass or more and less than 0.1% by mass of tin, and the total content of the indium and the tin is 0.45% by mass or less.

For example, the conductor is made of multiple copper alloy wires twisted together.

Another embodiment of the plated wire comprises a copper alloy wire and a plating layer provided around the copper alloy wire, the copper alloy wire being made of a copper alloy containing 0.3% by mass or more and 0.45% by mass or less of indium, and having a tensile strength of 750 MPa or more, a conductivity of 78% IACS or more, and an elongation of 3% or less.

Another embodiment of the cable has a conductor made of a copper alloy wire, a plurality of core wires with an insulator covering the conductor, and a sheath covering the plurality of core wires together. The copper alloy wire is made of a copper alloy containing 0.3% to 0.45% by mass of indium. The tensile strength of the copper alloy wire is 800 MPa or more, and the electrical conductivity of the copper alloy wire is 80% IACS or more.

For example, the copper alloy in the cable contains 0.02% by mass or more and less than 0.1% by mass of tin, and the total content of the indium and the tin is 0.45% by mass or less.

A typical embodiment of the present invention can improve both the strength and electrical conductivity of the metal wire.

FIG. 1 is a perspective cross-sectional view of a metal wire according to an embodiment. FIG. 2 is a flow chart showing an example of a manufacturing process of the metal wire shown in FIG. 1 . FIG. 2 is a cross-sectional view of a cable including the metal wire shown in FIG. 1 . 4 is a cross-sectional view of one of a plurality of electric wires included in the cable shown in FIG. 3.

The following describes an embodiment of the present invention with reference to the drawings. In the following description, a metal wire made of a copper alloy with a wire diameter (outer diameter) of 100 μm or less is called a copper alloy wire. Also, a copper alloy wire before being drawn into a copper alloy wire is called a roughly drawn wire. Also, a copper alloy wire having a plating layer around it is called a plated wire.

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

In the following explanation, when the "tensile strength" and "elongation" of metal wire are described, a tensile test is performed on a test piece in accordance with the test method for electrical copper wire specified in the Japanese Industrial Standards (JIS C 3002:1992), and the values calculated from the measurement results are taken as the "tensile strength" and "elongation."

<Metal Wire Structure>
Fig. 1 is a perspective cross-sectional view of a metal wire according to the present 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 0.45 mass% or less of indium (In). The copper alloy 11 contains inevitable impurities as the remainder. The tensile strength of the copper alloy wire 10 is 800 MPa or more (preferably, 800 MPa or more and 900 MPa or less), and the electrical conductivity of the copper alloy wire 10 is 80% IACS or more (preferably, 80% IACS or more and 85% IACS or less).

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 or more and 30 ppm by mass or less.

The copper alloy wire 10 having the above-mentioned copper alloy 11 can achieve both high levels of tensile strength and electrical conductivity. Details will be described later as an example, but as a result of confirmation by the present inventor, a copper alloy wire 10 having a copper alloy 11 containing 0.3 mass% or more and 0.45 mass% or less of indium (In), with the remainder being copper (Cu) and unavoidable impurities, has an electrical conductivity of 80% IACS or more. In addition, the tensile strength of the copper alloy wire 10 was 872 MPa or more. The value of the tensile strength of the copper alloy wire 10 may vary depending on the manufacturing conditions, but even taking into account the variation due to the manufacturing conditions, a value of at least 800 MPa or more can be obtained.

A conductive wire that transmits electricity (hereinafter simply referred to as an electric wire) is a component that constitutes a power transmission path or an electric signal transmission path, and is widely used in various fields. Conductive materials such as various types of pure metals, alloys, or 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 a conductor in an electric wire.

As mentioned above, copper wires used as conductors in electric wires are used in various fields, but depending on the field of use, copper wires with a small wire diameter 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 wire diameter of a single copper wire may be required to be 100 μm or less. In addition, in the case of probe cables used in the medical field, they may be used for applications in which they are inserted into the patient's body, and copper wires with even smaller wire 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 ultra-fine wire.

The tensile strength 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 the conductivity of the copper alloy wire 10 decreases. In other words, there is a trade-off between increasing the tensile strength of the copper alloy wire 10 and increasing the conductivity of the copper alloy wire 10.

Therefore, in order to find a configuration that improves the electrical conductivity and tensile strength properties of the solid-solution strengthened copper alloy 11, the inventors of the present application focused on the effect of multiple types of metal elements on the decrease in electrical conductivity of the copper alloy 11 when they are solid-solved in the copper alloy 11, and the degree to which they contribute to strengthening the tensile strength. In other words, the degree of contribution to strengthening the tensile strength of the copper alloy wire 10 varies depending on the type of metal element, and the tensile strength increases proportionally as the content of the element that is solid-solved in copper increases. Tin (Sn) and indium (In) are effective additive elements because they have a large effect on increasing tensile strength when solid-solved in copper, compared to metals such as aluminum (Al), nickel (Ni), or magnesium (Mg).

On the other hand, the degree of influence on the decrease in electrical conductivity varies greatly depending on the type of metal element. In more detail, in the case of silver (Ag), indium (In), or magnesium (Mg), the decrease in electrical conductivity can be suppressed even if the concentration of the metal elements dissolved in copper is large, compared to metals such as nickel (Ni), tin (Sn), and aluminum (Al). For example, when the concentration (mass concentration) of the above metal elements dissolved in oxygen-free copper is 900 ppm, the electrical conductivity of tin (Sn) decreases to about 92% of that of pure copper (percentage), but in the case of indium (In), the decrease is limited to about 98%. In addition, in the case of silver (Ag), the decrease is limited to about 99% of that of pure copper (percentage).

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

In addition, in order to improve the tensile strength of copper alloy 11, it is preferable that the oxygen content in the copper alloy is low. In the present embodiment, the oxygen content in copper alloy 11 is 0.002 mass% or less. If the oxygen content in copper alloy 11 is 0.002 mass% or less, it is possible to suppress a decrease in the tensile strength of copper alloy 11 due to oxygen.

As a modified example of the copper alloy wire 10 shown in FIG. 1, the copper alloy 11 may contain 0.3 mass% or more and less than 0.43 mass% indium (In), 0.02 mass% or more and less than 0.1 mass% tin (Sn), and the remainder may be copper (Cu) and unavoidable impurities. However, the total content of indium and tin contained in the copper alloy 11 is 0.45 mass% or less.

In the case of the modified copper alloy wire 10, the copper alloy 11 contains tin in solid solution, so 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 containing 0.3 mass% or more of indium, it is possible to maintain an electrical conductivity of 80% IACS or more. However, it is preferable that the total content of indium and tin contained in the copper alloy 11 is 0.45 mass% or less. According to the experimental results described below, within the range of the above-mentioned conditions, the tensile strength of the modified copper alloy wire 10 was 872 MPa or more. Thus, in the case of the modified copper alloy wire 10, by making the tin in solid solution, 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.

<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 of the metal wire shown in Fig. 1.

The following describes a method for manufacturing metal wire, in which a rough wire with a certain wire diameter (e.g., about 8 mm to 12 mm) is manufactured by a continuous casting and rolling method, and then the rough wire is drawn to manufacture metal wire. The continuous casting and rolling method can be, for example, a continuous casting and rolling method called the SCR method (Southwire Continuous Rod system).

First, in the raw material preparation step shown in FIG. 2, the raw material is prepared. The raw material is a metal whose main component is copper. 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 whose main component is copper within a range that satisfies the above-mentioned content conditions.

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 capable of continuously melting the raw materials, and the molten copper melted in the melting furnace is transferred sequentially to a heat-retaining furnace (not shown).

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 sent sequentially 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 rough wire 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.

Next, in the rolling process shown in Figure 2, the casting is rolled to form a roughly drawn wire with a wire diameter of about 8 mm to 12 mm. In the rolling process, the rolling process may be performed multiple times. Note that if the casting obtained in the casting process is used as a roughly drawn wire as is, this rolling process can be omitted.

Next, in the winding process shown in FIG. 2, the wire is wound by a winding device (not shown) to obtain a roughly drawn wire. The roughly drawn wire wound by the winding device has a tensile strength of 250 MPa or more and 300 MPa or more, and a conductivity of more than 85% IACS and approximately 90% IACS or less.

Next, in the wire drawing 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 the copper alloy wire 10 shown in FIG. 1. The wire drawing process is performed at room temperature (for example, 25° C.), so-called cold processing. In the wire drawing process, the roughly drawn wire is extended in the extension direction, but the wire drawing process is divided into multiple processes (a first wire drawing process and a second wire drawing process), and a heat treatment process (sometimes called an annealing process) is performed between the wire drawing processes to apply heat treatment to the drawn wire material during the wire drawing process. In the first wire drawing process, it is preferable to draw the roughly drawn wire (for example, a wire diameter of about 8 mm to 12 mm) to the desired wire diameter (for example, a wire diameter of 0.5 mm to 3.0 mm) by one wire drawing process. This type of wire drawing process is effective in bringing the electrical conductivity, tensile strength, and elongation of the metal wire into the desired range after the heat treatment process, and in ensuring that the copper alloy wire 10 obtained through the second wire drawing process has an electrical conductivity of 80% IACS or more and a tensile strength of 800 MPa or more.

During the wire drawing process, distortion occurs in the metal wire, which increases the tensile strength of the metal wire, but decreases the electrical conductivity of the metal wire. If heat treatment (sometimes called annealing) is performed during the wire drawing process, the distortion in the metal wire is reduced. As a result, the tensile strength of the heat-treated metal wire decreases, but its electrical conductivity increases. According to the research of the present inventors, it has been found that the tensile strength and electrical conductivity of the finally obtained hard metal wire (copper alloy wire 10) can be maintained at a high level by performing a heat treatment process during the wire drawing process (between the first wire drawing process and the second wire drawing process) so as to satisfy the following conditions. Note that the hard copper alloy wire referred to here is a metal wire with an elongation of 0.5% to 3%.

If the tensile strength of the metal wire before heat treatment (after the wire drawing process immediately before heat treatment) is A, the tensile strength of the metal wire after heat treatment (immediately after heat treatment) is B, and C = B/A, heat treatment is performed so that the tensile strength ratio C is 0.5 to 0.8. If the elongation of the metal wire before heat treatment (after the wire drawing 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. As shown in Figure 2, in order to further perform wire drawing after the heat treatment process, it is preferable to perform heat treatment in the heat treatment process so that the conductivity of the metal wire immediately after the heat treatment process is 86% IACS or more (preferably 88% IACS or more). In addition, it is preferable that the tensile strength of the metal wire immediately after the heat treatment process is 200 MPa to 300 MPa, and the elongation of the metal wire immediately after the heat treatment process 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 should be performed at a temperature of, for example, 400°C or higher and 900°C or lower.

In FIG. 2, the rough wire is drawn to a desired wire diameter (e.g., 0.5 mm to 3.0 mm) by a wire drawing process (first wire drawing process), and then the heat treatment process is performed to heat treat the metal wire under the above-mentioned conditions, and the wire is drawn to a desired wire diameter (e.g., 0.1 mm or less) by a wire drawing process (second wire drawing process). However, various modified examples are applicable. For example, the second wire drawing process may be divided into multiple wire drawing processes, and the metal wire may be drawn stepwise to the desired wire diameter by each step in the multiple wire drawing processes. In the second wire drawing process, the metal wire is drawn stepwise by multiple wire drawing processes, so that the above-mentioned hard metal wire (copper alloy wire 10) can be obtained more stably than when the second wire drawing process is composed of a single wire drawing process. In addition, when the second wiredrawing process is composed of multiple wiredrawing processes, the above-mentioned heat treatment process may be provided between the multiple wiredrawing processes as necessary. In addition, after the second wiredrawing process, heat treatment may be performed so that the metal wire maintains its hard state.

<Evaluation of alloy composition and properties>
Next, the results of an experiment will be described regarding the relationship between the alloy composition and characteristics of the copper alloy wire 10 shown in Fig. 1. Table 1 shows the relationship between the alloy composition and characteristics of the metal wire.

In Table 1, Samples No. 1 to 7 are examples that meet the conditions of the copper alloy wire 10 described above, and Samples No. 8 to 14 are comparative examples that do not meet the conditions of the copper alloy wire 10 described above. Each of Samples No. 1 to 14 was manufactured by the manufacturing method described using FIG. 2. In addition, in Table 1, the samples used in the tensile strength test and elongation test are metal wires processed to have a wire diameter of about 80 μm. The copper alloy wires used in Samples No. 1 to 14 are composed of copper alloys containing indium (In) and tin (Sn) with the contents shown in Table 1, and the balance being copper (Cu) and unavoidable impurities. In addition, the tensile speed was 20 mm/min, and the gauge length when measuring the elongation was 100 mm. The tensile strength was determined by dividing the maximum breaking load value by the cross-sectional area of the sample. 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 with a micrometer. The elongation value is the total elongation at break (the combined elastic 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 No. 1 to 14 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.

As can be seen by comparing samples No. 1, 5, 6, 8, 11, and 12 in Table 1, if the indium content is 0.30 mass% or more, the tensile strength of the sample can be 800 MPa or more and the electrical conductivity can be 80% IACS or more. Also, as can be seen by comparing samples No. 3, 4, and 10, if tin is not added as an additive element and the indium content is 0.45 mass% or less, the tensile strength of the sample can be 800 MPa or more and the electrical conductivity can be 80% IACS or more.

In addition, as can be seen by comparing samples No. 5, 8, 9, and 14 in Table 1, when indium and tin are added to a copper alloy, if the tin content is 0.02 mass% or more and less than 0.1 mass%, the tensile strength of the sample can be 800 MPa or more and the electrical conductivity can be 80% IACS or more. However, as can be seen by comparing samples No. 7 and 13, it is preferable that the total content of indium and tin is 0.45 mass% or less.

<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 multiple electric wires included in the cable shown in Fig. 3.

The cable 60 shown in FIG. 3 has multiple electric wires (core wires) 70 and a sheath 61 that covers the multiple electric wires 70 together. The cable 60 is a cable used in, for example, portable electronic devices or industrial robots. The outer diameter of the cable 60 is, for example, about 4.8 mm. The cable 60 has multiple electric wires 70, and each of the multiple electric wires 70 has a small outer diameter. For example, in the example shown in FIG. 3 and FIG. 4, the outer diameter of the electric wire 70 is, for example, about 0.86 mm (860 μm).

As shown in FIG. 4, the electric wire 70 has a central conductor 71 made of multiple copper alloy wires 10 twisted together, and an insulator 72 covering the central conductor 71. Each of the multiple copper alloy wires 10 constituting the central conductor 71 is made of the copper alloy 11 described with reference to FIG. 1. The copper alloy 11 constituting this copper alloy wire 10 contains 0.3 mass % or more and 0.45 mass % or less of indium, and tin whose total content with indium is 0.45 mass % or less. The wire diameter of each of the multiple copper alloy wires 10 is, for example, 0.08 mm (80 μm).

In this way, the electric wire 70 using multiple copper alloy wires 10 and the cable 60 using the same can improve the transmission characteristics of electrical signals or power sources within portable electronic devices. Alternatively, the electric wire 70 using multiple copper alloy wires 10, which are extremely fine wires, and the cable 60 using the same can have a small wire diameter, making it possible to reduce the size of the housing of portable electronic devices and to miniaturize industrial robots, etc.

In FIG. 4, the electric wire 70 is shown as an example, but there are various modified examples of the electric wire to which the copper alloy wire 10 shown in FIG. 1 is applied. For example, it can be applied to an electric wire consisting of a conductor made of one copper alloy wire 10 and an insulator that covers the conductor. In addition, in FIG. 3 and FIG. 4, the central conductor 71 of the electric wire 70 is shown as being made of a plurality of twisted copper alloy wires 10, but this is not limited thereto, and the central conductor 71 may be made of a plated wire, which will be described later.

<Plated wire>
The plated wire is configured with a plating layer around (on the outer surface of) the copper alloy wire 10 shown in Fig. 1. The plated wire has a tensile strength of 750 MPa or more, a conductivity of 78% IACS or more, and an elongation of 3% or less. That is, in a state where the plating layer is provided around the copper alloy wire 10 shown in Fig. 1, the plated wire has a tensile strength of 750 MPa or more (preferably, 750 MPa or more and 900 MPa or less), a conductivity of 78% IACS or more (preferably, 78% IACS or more and 85% IACS or less), and an elongation of 3% or less (preferably, 0.5% or more and 3% or less). The plated wire 30 is a hard wire.

As described above, the copper alloy wire 10 is made of a copper alloy containing 0.3 mass% or more and 0.45 mass% or less of indium (In). In particular, the copper alloy wire 10 is preferably made of a copper alloy containing 0.3 mass% or more and 0.45 mass% or less of indium (In), with the remainder being copper (Cu) and unavoidable impurities.

The plating layer is provided around the copper alloy wire 10 so as to contact the outer 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.

<Method of manufacturing plated wire>
The plated wire is obtained by forming a plating layer on the copper alloy wire 10 obtained by the manufacturing method of the copper alloy wire 10 shown in FIG. 2. The copper alloy wire 10 before forming the plating layer is a metal wire in a hard state having a tensile strength of 800 MPa or more and an electrical conductivity of 80% IACS or more. The copper alloy wire 10 is immersed in a plating tank in which a molten plating material (e.g., Sn) having a predetermined temperature (e.g., 250°C or more and 300°C or less) is stored. In this way, the hot-dip plating is applied to the entire outer surface of the copper alloy wire 10. Thereafter, the copper alloy wire 10 in a state in which the hot-dip plating is applied is passed through a plating die to adjust the thickness of the hot-dip plating applied to the surface of the copper alloy wire 10, and a plating layer having a predetermined thickness is formed. In particular, the conditions for applying the hot-dip plating to the surface of the copper alloy wire 10 are preferably a line speed of 100 m/min or more and an immersion time in the hot-dip plating of 0.1 seconds to 1.0 seconds. The plated wire on which the plating layer is formed in this manner maintains a hard state, and the elongation of the plated wire is 0.5% to 3.0%. Before applying hot-dip plating to the surface of the copper alloy wire 10, the copper alloy wire 10 may be heat-treated at a predetermined temperature (e.g., 300°C to 500°C). The heat treatment time when the copper alloy wire 10 is heat-treated is, for example, 0.1 seconds to 1.0 seconds, and the copper alloy wire 10 is immersed in the hot-dip plating of the next process while maintaining the hard state. This heat treatment may be performed in the same production line as the process of forming the plating layer, or may be performed in a production line different from the process of forming the plating layer.

<Characteristics of plated wire>
Next, the results of an experiment on the characteristics of the plated wire will be described. Table 2 shows the relationship between the alloy composition of the copper alloy wire constituting the plated wire and the characteristics of the plated wire.

In Table 2, Samples No. 15 to 20 are examples that meet the above-mentioned conditions for plated wire. Each of Samples No. 15 to 20 is a copper alloy wire manufactured by the manufacturing method described with reference to FIG. 2, with a plating layer formed around it. Specifically, the copper alloy wire manufactured by the manufacturing method described with reference to FIG. 2 is immersed in a plating tank containing molten Sn (temperature: 250°C to 300°C), and then the copper alloy wire with the hot-dip coating applied thereto is 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 having a predetermined thickness. In addition, in Table 2, the samples used in the tensile strength test and elongation test of plated wire are copper alloy wires processed to have a wire diameter of about 80 μm (Samples No. 15 to 17) or about 50 μm (Samples No. 18 to 20), with a plating layer (thickness: about 0.5 μm) formed around them. Sample No. The copper alloy wires used in Nos. 15 to 20 are composed of a copper alloy containing indium (In) and tin (Sn) with the contents shown in Table 2, with the remainder being copper (Cu) and unavoidable impurities. The tensile speed was 20 mm/min, and the gauge length when measuring the elongation was 100 mm. The tensile strength was determined by dividing the maximum breaking load value by the cross-sectional area of the sample. 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 with a micrometer. The elongation value is the total elongation at break (the combination of the elastic elongation and plastic elongation of the extensometer) expressed as a percentage of the extensometer gauge length. Although not shown in Table 2, each of Samples Nos. 15 to 20 was prepared in an environment where oxygen was unlikely to be mixed in, and the oxygen contained in the copper alloy wire of each sample was 0.002 mass% or less.

As can be seen by comparing samples No. 15 to 20 in Table 2, if the indium content is 0.30 mass% or more, the tensile strength of the sample can be 750 MPa or more and the electrical conductivity can be 78% IACS or more. Also, as can be seen by comparing samples No. 15 and 16, even if tin is added as an added element, the tensile strength of the sample can be 750 MPa or more and the electrical conductivity can be 78% IACS or more, just like when tin is not added. The indium content of the copper alloy constituting the copper alloy wire is preferably 0.30 mass% or more and 0.45 mass% or less. Also, when indium and tin are added to the copper alloy constituting the copper alloy wire, if the tin content is 0.02 mass% or more and less than 0.1 mass%, the tensile strength of the sample can be 750 MPa or more and the electrical conductivity can be 78% IACS or more.

<Application examples of plated wire>
As described above, the plated wire can be used as a central conductor for constituting an electric wire or cable. Specifically, the electric wire has a central conductor made of a plurality of plated wires twisted together and an insulator covering the central conductor. In addition, the electric wire may be provided with a shield layer or sheath around it to form a cable.

The present invention is not limited to the above-described embodiments and examples, and various modifications are possible without departing from the spirit of the invention.

The above embodiment includes the following:

[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 elongate it to 0.1 mm or less;
Including,
The roughly drawn wire is made of a copper alloy and contains 0.3 mass% or more and 0.45 mass% or less of indium, and tin whose total content with the indium is 0.45 mass% or less.

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

[Appendix 3]
In Appendix 1 or 2,
In the step (d),
The heat treatment is performed so that the value of C is 0.5 or more and 0.8 or less, where A is the tensile strength of the metal wire that has been drawn after the step (c), B is the tensile strength of the metal wire that has been subjected to the heat treatment after the step (d), and C is the tensile strength ratio of B/A.
a tensile strength of the metal wire that has been subjected to the heat treatment after the step (d) is E, and an elongation ratio F=E/D is set to be 10 or more and 50 or less.

[Appendix 4]
In Appendix 3, in the (d) step, a heat treatment is performed so that the electrical conductivity of the metal wire immediately after the heat treatment in the (d) step is 86% IACS or more.

The present invention can be used for copper alloy wires that are used as conductors in internal wiring cables (e.g., ultra-fine coaxial cables) for small electronic devices (e.g., digital cameras, surveillance cameras, personal computers, smartphones, etc.) and in flexible cables (e.g., endoscope cables, probe cables, etc.) used in industrial robots and medical devices (e.g., gastroscopes, ultrasound diagnostic devices, etc.).

10 Copper alloy wire 10D Wire diameter 11 Copper alloy 60 Cable 61, 74 Sheath (insulator)
70 Electric wire (core wire, coaxial cable)
71 central conductor 72 insulator 73 outer conductor

Claims (5)

A copper alloy wire made of a copper alloy,
The copper alloy contains 0.3 mass% or more and 0.45 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 0.45 mass% or less, and the balance being copper and unavoidable impurities ;
The tensile strength is 800 MPa or more,
A copper alloy wire having a conductivity of 80% IACS or more. A conductor made of a copper alloy wire;
and an insulator covering the conductor.
The copper alloy wire is made of a copper alloy having a composition containing 0.3 mass% or more and 0.45 mass% or less of indium and 0.02 mass% or more and less than 0.1 mass% of tin, a total content of the indium and the tin being 0.45 mass% or less, and the remainder being copper and unavoidable impurities ;
The copper alloy wire has a tensile strength of 800 MPa or more,
The electrical conductivity of the copper alloy wire is 80% IACS or more. The electric wire according to claim 2 ,
The conductor is an electric wire formed by twisting together a plurality of the copper alloy wires. A plurality of core wires each including a conductor made of a copper alloy wire and an insulator covering the conductor;
a sheath that collectively covers the plurality of core wires;
A cable having
The copper alloy wire is made of a copper alloy having a composition containing 0.3 mass% or more and 0.45 mass% or less of indium and 0.02 mass% or more and less than 0.1 mass% of tin, a total content of the indium and the tin being 0.45 mass% or less, and the remainder being copper and unavoidable impurities ;
The copper alloy wire has a tensile strength of 800 MPa or more,
A cable, wherein the electrical conductivity of the copper alloy wire is 80% IACS or more. A copper alloy wire and a plating layer provided around the copper alloy wire,
The copper alloy wire is made of a copper alloy having a composition containing 0.3 mass% or more and 0.45 mass% or less of indium and 0.02 mass% or more and less than 0.1 mass% of tin, a total content of the indium and the tin being 0.45 mass% or less, and the remainder being copper and unavoidable impurities ;
A plated wire having a tensile strength of 750 MPa or more, a conductivity of 78% IACS or more, and an elongation of 3% or less.