Wire conductor and insulation wire

Abstract

To provide a wire conductor excellent in wire strength and connection strength when connecting to a connector terminal even when a conductor cross-section area is made smaller than 0.13 mm2, and an insulation wire equipped with such wire conductor.SOLUTION: A wire conductor 10 consists of a core wire 11 of single-wire made of stainless steel and a copper coating layer 12 that is made of copper or a copper alloy, covering an outer circumference of the core wire. The conductor cross-sectional area is less than 0.13 mm2, the electrical resistance is 660 mΩ / m or less, the tensile strength is between 950 MPa and 1080 MPa, and the elongation at break is 1.5% or more, and it is used in a single wire state. The insulated wire 1 has the wire conductor 10 and an insulating coating 20 that covers the outer circumference of the wire conductor 1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to electrical conductors and insulated wires. [Background technology]

[0002] In automobiles, communication wires are connected to various communication devices via connectors, but as devices become smaller, connectors are also becoming smaller and lighter. As connectors become smaller, the communication wires connected to them are also required to have smaller diameters. For example, Patent Document 1 describes a stranded conductor using wires of a Cu alloy containing Fe, with a conductor cross-sectional area of ​​0.13 mm 2 In general, smaller sizes are used. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-085344 A [Patent Document 2] JP 2018-37324 A Summary of the Invention [Problem to be solved by the invention]

[0004] The conductor used in the above Patent Document 1 has a conductor cross-sectional area of ​​0.13 mm 2 Even if the conventional copper alloy stranded wire is thinned to a certain extent, the wire strength and connection strength when connecting to a connector can be sufficiently ensured. However, with the recent miniaturization of connectors, 2 There is also a demand for communication cables that are even smaller than the conductor cross-sectional area of ​​0.13 mm. 2 In the region smaller than 100 mm, it is difficult to reduce the diameter of the stranded conductor, so it is possible to consider making the conductor into a solid wire. However, if a conventional copper alloy wire is used as a solid wire, it is difficult to ensure sufficient wire strength. In addition, the connection strength when connecting to a connector terminal is likely to be low.

[0005] Therefore, the conductor cross-sectional area is set to 0.13 mm 2 The present invention aims to provide an electric wire conductor that has excellent wire strength and connection strength when connected to a connector terminal even when the electric wire conductor is smaller than 1 mm in diameter, and an insulated electric wire including such an electric wire conductor. [Means for solving the problem]

[0006] The electric wire conductor of the present disclosure has a conductor cross-sectional area of ​​0.13 mm 2 It has an electrical resistance of 660 mΩ / m or less, a tensile strength of 950 MPa or more, and a breaking elongation of 1.5% or more, and is used in the form of a single wire.

[0007] The insulated wire of the present disclosure includes the conductor and an insulating coating that covers the outer periphery of the conductor. Effect of the Invention

[0008] The electric wire conductor and the electric wire for communication according to the present disclosure have a conductor cross-sectional area of ​​0.13 mm 2 Even if the diameter of the wire conductor is smaller than the diameter of the wire conductor, the wire conductor has excellent wire strength and excellent connection strength when connected to a connector terminal, and an insulated wire including such a wire conductor can be obtained. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing a solid insulated wire according to one embodiment of the present disclosure. [Diagram 2] 2A and 2B are cross-sectional views showing a flat electric wire, each showing a different form. [Diagram 3] Fig. 3 is a diagram showing the evaluation results of the relationship between the physical properties of the electric wire conductor and the crimping strength. As the physical properties of the electric wire conductor, the upper row shows the tensile strength of the electric wire conductor, the middle row shows the hardness of the core wire, and the lower row shows the hardness of the copper coating layer. The left column shows the case of low compression, and the right column shows the case of high compression. [Figure 4]Figure 4 shows the evaluation results of the relationship between the tensile strength and crimp strength of the electric wire conductor when SUS 304H and SUS 304L are used for the core wire. The figure also shows the breaking elongation of the electric wire conductor. The upper figure shows the case of low compression, and the lower figure shows the case of high compression. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. The electric wire conductor according to the present disclosure has a conductor cross-sectional area of ​​0.13 mm 2 It has an electrical resistance of 660 mΩ / m or less, a tensile strength of 950 MPa or more, and a breaking elongation of 1.5% or more, and is used in the form of a single wire.

[0011] The above electric wire conductor has a high tensile strength of 950 MPa or more and a breaking elongation of 1.5% or more. 2 Even though the wire conductor is small at less than 1000 mm, it has high wire strength and provides excellent connection strength when connected to a connector terminal. In addition, the electrical resistance of the wire conductor is suppressed to 660 mΩ / m or less, which is a sufficiently low level for use as a communication wire. Therefore, the above-mentioned wire conductor can be suitably used to form a communication wire to be connected to a small connector.

[0012] Here, it is preferable that the tensile strength of the electric conductor is 1300 MPa or less, which can prevent a situation in which the strength of the terminal material is reduced or the electric conductor is not sufficiently compressed to be in close contact with the terminal material when connecting to a connector terminal by crimping, due to the strength of the electric conductor being too high, thereby preventing a decrease in the crimping strength of the crimped portion.

[0013] The electric wire conductor may have a solid core wire made of stainless steel and a copper coating layer made of copper or a copper alloy and coating the outer periphery of the core wire. The electric wire conductor having a core wire made of stainless steel and a copper coating layer is likely to achieve a tensile strength of 950 MPa or more and a breaking elongation of 1.5% or more as a whole electric wire conductor. In addition, the contribution of the copper coating layer makes it easy to suppress the electrical resistance of the electric wire conductor to 660 mΩ / m or less.

[0014] In the cross section of the electric wire conductor, the hardness of the core wire is preferably 650 Hv or more and 750 Hv or less, and the hardness of the copper coating layer is preferably 80 Hv or more and 120 Hv or less. If the core wire and the copper coating layer constituting the electric wire conductor have hardnesses in these ranges, the electric wire conductor as a whole will have particularly excellent tensile strength and crimping strength.

[0015] The tensile strength of the core wire is preferably 2400 MPa or more and 2800 MPa or less, so that the electric conductor has particularly excellent tensile strength and crimping strength.

[0016] The stainless steel constituting the core wire preferably has a breaking elongation of 1.7% or more when heat-treated at a temperature of 150°C to 400°C for 1 hour. By using a core wire having high tensile strength and elongation, the electric wire conductor tends to exhibit high crimping strength as a whole. In addition, even if the tensile strength of the electric wire conductor varies slightly due to fluctuations in heat treatment conditions, the electric wire conductor can provide a stable high crimping strength.

[0017] The stainless steel constituting the core wire is preferably SUS 304H, which is a material that exhibits high tensile strength and breaking elongation and can be suitably used as a constituent material of the core wire.

[0018] The insulated wire according to the present disclosure includes the conductor and an insulating coating that covers the outer circumference of the conductor. 2The wire has a small conductor cross-sectional area of ​​less than 100 mm and has excellent small diameter, but by using a wire conductor having the above-mentioned specified physical properties, it exhibits high wire strength and terminal connection strength. Therefore, it can be suitably used in automobiles, etc. as a communication wire connected to a small connector.

[0019] Here, it is preferable that a plurality of the electric wire conductors are arranged in parallel, the outer circumference of each of the electric wire conductors is covered with the insulating coating to form a coating portion, and the coating portions are connected to each other by a connecting portion that is integrated with the insulating coating of the coating portion. By arranging a plurality of electric wire conductors in parallel, the strength of the insulated electric wire as a whole is further improved. Furthermore, by arranging a plurality of electric wire conductors in parallel and stably maintaining the distance between the electric wire conductors by the connecting portion, the insulated electric wire can be used as a communication electric wire with stable communication characteristics.

[0020] In this case, it is preferable that the distance between at least one pair of adjacent conductors is 0.2 mm or more and 1.2 mm or less, so that the two conductors can be suitably used as a pair of wires for transmitting differential signals while maintaining sufficient insulation between the conductors.

[0021] [Details of the embodiment of the present disclosure] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. In this specification, the terms "parallel" and "perpendicular" that indicate the shape and arrangement of the components include not only a strict geometrical concept but also an error range that is generally acceptable for a communication cable. In addition, in this specification, various physical properties are values ​​measured in the atmosphere at room temperature (approximately 15 to 25°C).

[0022] <Outline of Electric Wire Conductors and Communication Wires> The communication wire according to the embodiment of the present disclosure has a conductor cross-sectional area of ​​0.13 mm 2The insulated wire according to the embodiment of the present disclosure has the above-mentioned conductor and an insulating coating that covers the outer periphery of one piece of the conductor.

[0023] The electric wire conductor according to the embodiment of the present disclosure is used in a solid wire state. In other words, the electric wire conductor is used in a state in which each electric wire is individually insulated, and a plurality of uninsulated electric wire conductors are not used in a state of being bundled together by twisting or forming a bundle. The electric wire conductor has a conductor cross-sectional area of ​​0.13 mm 2 The wire conductor has such a small cross-sectional area that the insulated wire can be made thinner, making it suitable for use in connecting to small connectors in automobiles. 2 A thin electric wire conductor having a cross-sectional area of ​​less than 0.10 mm can be used more suitably for communication purposes than for electrical current carrying purposes. 2 Although there is no particular lower limit to the conductor cross-sectional area, from the viewpoint of suppressing a decrease in strength due to excessive thinning, it is preferable that the conductor cross-sectional area is, for example, 0.02 mm 2 It is recommended to set it at 0.05mm or more. 2 The conductor cross-sectional area of ​​660 mΩ / m or less can be particularly preferably used. Furthermore, the electric wire conductor has an electric resistance of 660 mΩ / m or less. If the electric wire conductor has an electric resistance of 660 mΩ / m or less, it has sufficient conductivity as an electric wire for communication. More preferably, the electric wire conductor has an electric resistance of 600 mΩ / m or less.

[0024] The electric wire conductor according to the present embodiment has a tensile strength of 950 MPa or more. If the tensile strength of the electric wire conductor is 950 MPa or more, a sufficiently high electric wire strength can be obtained in the electric wire conductor, which is a thin single wire, and insulated electric wire including the electric wire conductor. In addition, when the electric wire conductor is crimped and connected to a connector terminal, a high connection strength can be obtained at the crimped portion. In other words, the electric wire conductor compressed at the crimped portion is less likely to break. From the viewpoint of further enhancing these effects, it is more preferable that the tensile strength of the electric wire conductor is 970 MPa or more, 1000 MPa or more, or 1050 MPa or more. The tensile strength of the electric wire conductor can be evaluated as the tensile strength at break by a tensile test in accordance with JIS Z 2241.

[0025] Although the upper limit of the tensile strength of the electric wire conductor is not particularly set, if the tensile strength is too high, the connection strength at the connection part with the connector terminal may be lowered. If the electric wire conductor has high strength and becomes too hard, when the electric wire conductor is crimped to the connector terminal, the strength of the material on the connector terminal side may decrease, or the electric wire conductor may not be sufficiently deformed, so that the connector terminal may not be able to hold the electric wire conductor firmly, and the connection strength may be lowered. In order to avoid such situations and to ensure high connection strength, it is preferable to keep the tensile strength of the electric wire conductor at 1300 MPa or less, 1180 MPa or less, or 1080 MPa or less.

[0026] Furthermore, the electric wire conductor according to the present embodiment has a breaking elongation of 1.5% or more. Since the electric wire conductor has a breaking elongation of 1.5% or more in addition to a tensile strength of 950 MPa or more, when the electric wire conductor is connected to a crimp terminal, a high crimping strength can be obtained at the crimping portion by utilizing the elongation of the electric wire conductor. Furthermore, if the electric wire conductor has a sufficiently high breaking elongation, even if the tensile strength of the electric wire conductor varies due to fluctuations in heat treatment conditions, etc., a high crimping strength can be stably obtained. From the viewpoint of further enhancing these effects, it is more preferable that the breaking elongation of the electric wire conductor is 1.8% or more, 2.0% or more, or 2.2% or more. The breaking elongation of the electric wire conductor can be evaluated by a tensile test in accordance with JIS Z 2241.

[0027] When the electric wire conductor has a tensile strength of 950 MPa or more and a breaking elongation of 1.5% or more, a high crimp strength, for example, 30 N or more, can be obtained at the crimped portion. This allows high connection strength to be obtained when the electric wire conductor is connected to a connector terminal. It is more preferable that the crimp strength is 40 N or more. The crimp strength of the electric wire conductor can be evaluated as the maximum force applied until the electric wire conductor breaks at the crimped portion when the electric wire conductor is pulled in a state in which the electric wire conductor is crimped and connected to the crimp terminal. Breakage at the crimped portion of the electric wire conductor according to this embodiment occurs not due to separation of the joint between the crimp terminal and the electric wire conductor, but due to breakage of the electric wire conductor itself inside the crimp terminal, so the crimp strength is determined as a parameter that is less dependent on the type of crimp terminal and the crimping method. As an example, a tensile test may be performed by clamping and compressing the electric wire conductor from opposing directions using a copper alloy crimp terminal in an axial region having a length of 1.6 to 3.0 mm, and crimping the electric wire conductor to perform a tensile test.

[0028] <Example of electric wire conductor and insulated wire: When electric wire conductor has two-layer structure> Next, as described above, the conductor cross-sectional area is reduced to 0.13 mm 2As an example of a single-wire electric conductor that has an electrical resistance of 660 mΩ / m or less, a tensile strength of 950 MPa or more, and an elongation at break of 1.5% or more when the thickness is less than 1.5 mm, an electric conductor having a two-layer structure of a core wire and a coating layer, and an insulated electric wire including such an electric conductor will be described. Fig. 1 shows a cross section of an insulated electric wire 1 including such an electric conductor 10. In the insulated electric wire 1, an insulating coating 20 is formed by coating the outer periphery of a single electric conductor 10.

[0029] The electric wire conductor 10 has a core wire 11 and a copper coating layer 12 that coats the outer circumference of the core wire 11. The core wire 11 and the copper coating layer 12 are bonded together. The core wire 11 is made of stainless steel (SUS). The type of SUS is not particularly limited, but austenitic SUS, particularly SUS 304H and SUS 304L, can be preferably used. The copper coating layer 12 is made of copper or a copper alloy. It is preferably made of pure copper that does not contain any additive elements except for unavoidable impurities. Other types of layers may be arranged between the core wire 11 and the copper coating layer 12 for the purpose of increasing the bonding between the core wire 11 and the copper coating layer 12, but it is preferable that the copper coating layer 12 is formed in direct contact with the surface of the core wire 11.

[0030] The chemical compositions of SUS 304H and SUS 304L are summarized in Table 1 below. The two differ from each other in the C and Ni contents. [Table 1]

[0031] The electric wire conductor 10 according to the present embodiment includes a core wire 11 made of SUS, and due to the high material strength of SUS, the electric wire conductor 10 as a whole has a high tensile strength of 950 MPa or more. Therefore, even in a solid wire state or when the diameter is reduced, the electric wire conductor 10 has a higher conductor strength than a conventional conductor made entirely of a copper alloy. The connection strength when connecting a connector can also be increased. The specific characteristics of the core wire 11 will be described in detail later, but in order to exert sufficient strength in the electric wire conductor 10, the outer diameter of the core wire 11 is preferably 0.11 mm or more, more preferably 0.12 mm or more. On the other hand, in order to ensure a sufficient thickness of the copper coating layer 12 while maintaining the thinness of the electric wire conductor 10, the outer diameter of the core wire 11 is preferably 0.17 mm or less.

[0032] In the electric wire conductor 10, the copper coating layer 12 is responsible for electrical conduction. Although the SUS constituting the core wire 11 is not a metal having a particularly high electrical conductivity, in order to ensure sufficient electrical conductivity of the electric wire conductor 10 as a whole, the copper coating layer 12 made of copper or a copper alloy, which is a metal having a high electrical conductivity, is provided on the outer periphery of the core wire 11. The thickness of the copper coating layer 12 is determined so that the electric resistance of the electric wire conductor 10 as a whole is 660 mΩ / m or less, preferably 600 mΩ / m or less. There is no particular lower limit for the electric resistance of the electric wire conductor 10, but it is preferable to set it to, for example, 500 mΩ / m or more from the viewpoint of preventing the copper coating layer 12 from becoming too thick. Generally, the thickness of the copper coating layer 12 may be set to 40 μm or more and 70 μm or less.

[0033] The insulating coating 20 is made of an organic polymer as a base material. The type of organic polymer is not particularly limited, and olefin-based polymers such as polyolefins and olefin-based copolymers, halogen-based polymers such as polyvinyl chloride, various elastomers, rubbers, etc. can be used. Various additives may be added to the organic polymer as appropriate. The thickness of the insulating coating 20 is not particularly limited, but from the viewpoint of providing sufficient insulation, it is preferable to set it to, for example, 0.1 mm or more. On the other hand, from the viewpoint of increasing the thinness of the insulated wire 1, it is preferable to keep it to 0.25 mm or less.

[0034] <Characteristics of two-layered electric wire conductor> Next, the characteristics of the electric wire conductor 10 having the above-mentioned two-layer structure of the SUS core wire 11 and the copper coating layer 12 will be described in detail.

[0035] The electric wire conductor 10 has high strength due to the core wire 11 made of SUS. Specifically, as described above, the electric wire conductor 10 as a whole has a tensile strength of 950 MPa or more. The tensile strength of the electric wire conductor 10 is preferably 970 MPa or more, more preferably 1000 MPa or more, and even more preferably 1050 MPa or more. Moreover, the tensile strength of the electric wire conductor 10 is preferably restricted to 1300 MPa or less, more preferably 1180 MPa or less, and even more preferably 1080 MPa or less.

[0036] The breaking elongation of the electric wire conductor 10 as a whole is mainly governed by the breaking elongation of the core wire 11 made of SUS, but the copper coating layer 12 is made of copper or a copper alloy, which is a metal more flexible than SUS, and thus contributes to increasing the breaking elongation of the electric wire conductor 10. As a whole composite of the core wire 11 and the copper coating layer 12, the breaking elongation of the electric wire conductor 10 is 1.5% or more, as described above. It is more preferable that the breaking elongation of the electric wire conductor 10 is 1.8% or more, 2.0% or more, or 2.2% or more.

[0037] As long as the electric wire conductor 10 as a whole exhibits the above-mentioned tensile strength and breaking elongation, each of the core wire 11 and the copper coating layer 12 made of SUS may have any material properties. However, in the cross section of the electric wire conductor 10, the core wire 11 preferably has a hardness of 650 Hv or more, and even 670 Hv or more. The tensile strength of the core wire 11 alone is preferably 2400 MPa or more, and even 2500 MPa or more. If the core wire 11 has a hardness and tensile strength equal to or greater than these values, the strength of the electric wire conductor 10 as a whole is easily increased. On the other hand, the hardness of the core wire 11 is preferably 750 Hv or less, and even 700 Hv or less. The tensile strength of the core wire 11 alone is preferably 2800 MPa or less, and even 2600 MPa or less. If the hardness and tensile strength of the SUS core wire 11 are suppressed to be equal to or less than these values, it is easy to suppress a decrease in crimping strength due to an excessive increase in the strength of the electric wire conductor 10.

[0038] Furthermore, when the core wire 11 made of SUS is subjected to heat treatment (annealing after drawing) at a temperature of 150°C to 400°C for 1 hour alone, the breaking elongation is preferably 1.7% or more, and further preferably 2.2% or more. This makes it easier to obtain the above breaking elongation for the entire electric wire conductor 10. An example of a SUS material that gives the core wire 11 a breaking elongation of 1.7% or more, and further preferably 2.2% or more under the above heat treatment conditions is SUS 304H.

[0039] The hardness of the copper coating layer 12 is preferably 80Hv or more. It is also preferably 160Hv or less, and further preferably 120Hv or less. The strength of the electric wire conductor 10 as a whole is greatly affected by the strength of the core wire 11, but the strength of the copper coating layer 12 also contributes to a certain extent. If the hardness of the copper coating layer 12 is set within the above range, the tensile strength and crimping strength of the electric wire conductor 10 as a whole can be effectively increased. The hardness of the SUS core wire 11 and the copper coating layer 12 can be measured using a micro Vickers hardness tester or the like on a cross section of the electric wire conductor 10 cut perpendicularly to the axial direction. In this case, the measurement is performed at about five points for each and the average value is taken.

[0040] <Manufacturing method for two-layered electric wire conductor> As a method for manufacturing the electric wire conductor 10 having the above-mentioned two-layer structure, for example, a SUS core wire 11 having a predetermined diameter may be manufactured by wire drawing, and then a copper coating layer 12 may be formed by plating or vapor deposition on the surface of the core wire 11. Alternatively, the electric wire conductor 10 may be manufactured by fitting a ring-shaped copper material that will become the copper coating layer 12 around the SUS material that will become the core wire 11, and drawing the two together to a predetermined diameter.

[0041] The electric wire conductor 10 having the copper coating layer 12 on the surface of the SUS core wire 11 thus obtained may be subjected to heat treatment (annealing). Through the heat treatment, mainly the copper coating layer 12 is softened. The heat treatment conditions may be set so that the electric wire conductor 10 as a whole has the desired tensile strength, hardness, and breaking elongation. The heat treatment temperature may be in the range of 100°C or more and 400°C or less. More preferably, the heat treatment may be performed at 250°C or more and 400°C or less. The heat treatment may be performed by a continuous softening method in which the electric wire conductor 10 is heated by passing electricity through it, or by a batch type softening method in which the electric wire conductor 10 is heated in a batch furnace at a predetermined temperature.

[0042] <Another form of insulated wire – flat wire> The electric wire conductor according to the embodiment of the present disclosure, such as the electric wire conductor 10 having a two-layer structure, may be used in any form and is not limited to a form constituting a simple insulated electric wire 1 in which the entire circumference of a single electric wire conductor 10 is covered with an insulating covering 20 as shown in Fig. 1. As an example of a case in which an insulated electric wire of another form is constituted using the electric wire conductor 10 according to the above embodiment, a flat electric wire will be briefly described.

[0043] Cross sections of the flat electric wire 2 are shown in Fig. 2A and Fig. 2B. Fig. 2A and Fig. 2B show different forms. The flat electric wire 2 includes a plurality of electric wire conductors 10 according to the embodiment of the present disclosure described above. The number of electric wire conductors 10 is not particularly specified, but a number of 2 or more and 8 or less can be preferably adopted. In particular, it is sufficient that the number is an even number so that a pair wire can be formed.

[0044] In the flat electric wire 2, a plurality of electric wire conductors 10 are arranged in parallel in one direction with their axial directions aligned in parallel. The outer periphery of each arranged electric wire conductor 10 is individually covered with an insulating coating 20, and a plurality of covering parts 30 each consisting of the electric wire conductor 10 and the insulating coating 20 are formed. The covering parts 30 are connected to each other by a connecting part 25. The insulating coating 20 and the connecting part 25 constituting the covering part 30 are integrally formed using the same material. In the embodiment shown in FIG. 2A, the connecting part 25 is formed by connecting the covering parts 30 having a substantially circular cross section. On the other hand, in the embodiment shown in FIG. 2B, adjacent covering parts 30 are directly joined so that the substantially circular cross-sectional shapes are overlapped with each other, and a part of the insulating coating 20 constituting the covering parts 30 functions as the connecting part 25. In either form, from the viewpoints of ensuring the flexibility of the flat electric wire 2 and ease of tearing during terminal processing, it is preferable that the thickness of the connecting portion 25 (the dimension perpendicular to the parallel direction of the electric wire conductor 10) is smaller than the diameter of the covering portion 30.

[0045] The interval between the electric wire conductors 10 arranged in parallel is not particularly limited, but it is preferable that the distance d between adjacent electric wire conductors 10 (the distance between the centers of the electric wire conductors 10) is 0.2 mm or more, further 0.4 mm or more, or 0.8 mm or more. In this way, the insulation between the electric wire conductors 10 can be sufficiently ensured. In particular, in the embodiment of FIG. 2A, the distance d between adjacent electric wire conductors 10 is preferably 0.4 mm or more. On the other hand, it is preferable that the distance d between at least one pair of adjacent electric wire conductors 10 is 1.2 mm or less, further 1.0 mm or less. In this way, the two electric wire conductors 10 can be suitably used as a pair wire for transmitting a differential signal while ensuring a required characteristic impedance. Note that, when the flat electric wire 2 includes three or more electric wire conductors 10, the distance d between the electric wire conductors 10 may be longer than 1.2 mm at a location other than between the two electric wire conductors 10 constituting the pair, or all the electric wire conductors 10 may be arranged at equal intervals of 1.2 mm or less.

[0046] By using the flat electric wire 2, it becomes possible to connect a plurality of electric wire conductors 10 at once to a connector having a plurality of terminals arranged in a row. As described above, the electric wire conductor 10 according to the embodiment of the present disclosure has high strength, but by arranging a plurality of electric wire conductors 10 in parallel, the strength of the flat electric wire 2 as a whole can be further increased. In addition, since the electric wire conductor 10 has high strength, if independent insulated electric wires 1 as shown in FIG. 1 are twisted together to form a twisted pair wire, it is difficult to stably maintain the twisted structure due to the high rigidity of the electric wire conductor 10. However, by forming the flat electric wire 2 in which a plurality of electric wire conductors 10 are arranged horizontally and further by maintaining a constant distance d between the electric wire conductors 10 by the connecting portion 25, it becomes possible to stably transmit differential signals. EXAMPLES

[0047] Examples are shown below. Note that the present invention is not limited to these examples. Unless otherwise specified, the preparation and evaluation of samples were carried out in air at room temperature.

[0048] [1] Relationship between strength of two-layered electric wire conductor and crimp strength First, for a two-layered conductor having a SUS core wire and a copper coating layer, the relationship between the tensile strength of the entire conductor, the hardness of each part, and the crimp strength at the terminal crimp part was examined.

[0049] <Sample preparation> An electric wire conductor having a core wire made of SUS 304H material and a copper coating layer made of pure copper was produced. The outer diameter of the core wire was φ0.16 mm, and the thickness of the copper coating layer was 45 μm. The electric wire conductor as a whole had an outer diameter of φ0.25 mm and a conductor cross-sectional area of ​​0.05 mm. 2The obtained electric wire conductor was subjected to heat treatment by continuous softening. The heat treatment conditions were set so as to obtain the specified tensile strengths shown on the horizontal axis in the upper part of Fig. 3. The heating temperature was generally within the range of 100°C to 400°C. Separately, samples were prepared by batch heating and heat treatment at multiple temperatures between 100°C and 400°C for one hour. The electric resistance of the electric wire conductor was 660 mΩ / m or less regardless of the heat treatment conditions. In addition, a conductor with a conductor cross-sectional area of ​​0.05 mm2 was prepared as a reference sample. 2 A copper alloy conductor (tensile strength: 740 MPa, breaking elongation: 2.1%) was also prepared.

[0050] <Evaluation method> - Tensile strength of electric wire conductor The tensile strength at break of each of the produced electric wire conductors was evaluated by a tensile test conforming to JIS Z 2241. In this case, the time when the electric wire conductor broke as a whole was regarded as the time of break. In the measurement, the distance between marks was 250 mm, and the pulling speed was 50 mm / min.

[0051] Hardness of each part Each of the produced electric wire conductors was cut perpendicular to the axial direction, and the hardness of the core wire and the copper coating layer was measured on the cross section. The hardness was measured using a micro Vickers hardness tester. The core wire and the copper coating layer were each measured at five points, and the average value was recorded.

[0052] Crimping strength The prepared electric wire conductor was cut to a length of 104 mm and crimped with a crimp terminal to obtain a conductor with terminal. The crimp terminal was made of a copper alloy, and during crimping, the electric wire conductor was sandwiched and compressed from opposite directions in a region of 1.6 to 3.0 mm in length along the axial direction of the electric wire conductor. The degree of compression of the conductor was changed to form two types of crimped parts, low compression and high compression. The low compression state is employed in a connection between a normal connector terminal and an electric wire conductor, and the high compression state corresponds to a state in which the electric wire conductor is compressed under conditions that are harsher than normal.

[0053] A crimp terminal was fixed to the obtained conductor with terminal, and the electric wire conductor was pulled. The maximum force applied until the electric wire conductor broke at the crimped portion was recorded as the crimp strength. The pulling speed was 100 mm / min. Note that in all samples, the breakage of the crimped portion occurred not because the electric wire conductor separated from the crimp terminal and came out, but because the electric wire conductor itself broke inside the crimp terminal.

[0054] <Test Results> Figure 3 shows the relationship between various properties (horizontal axis) and crimp strength (vertical axis) for electric wire conductors that have undergone heat treatment by continuous softening. The properties shown on the horizontal axis are the tensile strength of the entire electric wire conductor at the top, the hardness of the SUS core wire at the middle, and the hardness of the copper coating layer at the bottom. The left column shows the cases of low compression, and the right column shows the cases of high compression. In each figure, the crimp strength level of 30N is shown with a solid line.

[0055] First, we will consider the results for low compression. Looking at the relationship between the tensile strength and crimp strength of the electric wire conductor, a crimp strength of 30N or more was obtained in the entire range of tensile strengths of 950MPa or more. In this case, the corresponding hardness of the SUS core wire and copper coating layer was 650Hv or more and 80Hv or more, respectively. Also, although a graph is not included, a crimp strength of 30N or more was obtained in the range of conductor tensile strengths from 1050MPa to 1300MPa in the samples that were heat treated by batch softening.

[0056] Next, we will consider the results in the case of high compression. In this case, a crimp strength of 30N or more was obtained in the range where the tensile strength of the electric wire conductor was generally between 950MPa and 1080MPa. In the range where the tensile strength was higher than 1080MPa, the crimp strength decreased. This is thought to be because the hardness of the electric wire conductor reduced the material strength of the crimp terminal, making it impossible to firmly hold the electric wire conductor with the crimp terminal. The crimp strength of the copper alloy conductor used as the reference sample was 23.6N in the case of low compression and 25.4N in the case of high compression.

[0057] [2] Consideration of the constituent materials of the core wire in a two-layered electric conductor Here, we examined the effect that the elongation of the SUS that constitutes the core wire has on the characteristics of the wire conductor in a two-layered structure.

[0058] <Sample preparation> In the above test [1], a core wire made of SUS 304H was used, but instead, a core wire made of SUS 304L was used to fabricate a conductor in the same manner. The conditions for the heat treatment by continuous softening were set so that the tensile strengths of the cases using SUS 304H and SUS 304L were roughly the same. In addition, SUS 304H and SUS 304L core wires without the copper coating layer were separately subjected to heat treatment by batch softening under the same conditions as the conductor with the copper coating layer.

[0059] <Evaluation method> Tensile strength and crimp strength For each sample that had been heat-treated by continuous softening, the tensile strength and crimp strength of the wire conductor were evaluated in the same manner as in test [1] above.

[0060] Elongation at break The elongation at break of each sample that had been heat-treated by continuous softening and batch-type softening was evaluated by a tensile test in accordance with JIS Z 2241. In addition, the electrical resistance was measured by the four-terminal method.

[0061] <Evaluation Results> Figure 4 shows the relationship between the tensile strength and crimp strength of the entire conductor when SUS 304H and SUS 304L are used for the core wire. In addition, the breaking elongation value of the entire conductor is displayed near each data point in the figure. The upper figure shows the case of low compression, and the lower figure shows the case of high compression. The data for SUS 304H shown in Figure 4 is the same as that shown in Figure 3.

[0062] According to Fig. 4, in a low compression state, a crimp strength of 30N or more is obtained in a region where the tensile strength of the electric wire conductor is 950MPa or more and the breaking elongation is 1.5% or more, whether the core wire is SUS 304H or SUS 304L. From this, it can be said that a sufficiently high crimp strength can be achieved in a normal terminal connection by using an electric wire conductor having a tensile strength of 950MPa or more and a breaking elongation of 1.5% or more. It is considered that the crimp strength is improved by the electric wire conductor showing high elongation during crimping.

[0063] Furthermore, a detailed comparison of the results for SUS 304H and SUS304L shows that in the case of low compression, SUS304H achieves a crimp strength of 30N or more at all data points, whereas SUS 304L has a lower crimp strength in the region of high tensile strength. In other words, SUS 304H has a wider region where a crimp strength of 30N or more can be achieved than SUS 304L. Similarly, in the case of high compression ratio, SUS 304H achieves a crimp strength of 30N or more in a wider region.

[0064] Thus, when the core wire is made of SUS 304H, a high crimp strength is stably obtained over a wide range of tensile strength compared to when it is made of SUS 304L. The difference in crimp strength between SUS 304H and SUS304L can be related to the difference in elongation between the two materials. Looking at the breaking elongation values ​​shown in Figure 4, SUS 304H tends to have a higher breaking elongation than SUS 304L, even though the tensile strengths are similar. In order to examine the difference in breaking elongation between the two types of SUS in more detail, Table 2 below summarizes the breaking elongation values ​​measured after batch softening at each temperature for both materials, for the core wire alone and with a copper coating layer. The electrical resistance measured with the copper coating layer is also shown.

[0065] [Table 2]

[0066] According to Table 2, the breaking elongation obtained after heat treatment of the core wire alone is larger for SUS 304H than for SUS 304L. When heat treated for 1 hour at 150°C to 400°C, the breaking elongation of SUS 304L remains at 2.0% or less, while that of SUS 304H is 2.2% or more. Even when a copper coating layer is formed on the outer circumference of the core wire, the tendency for SUS 304H to show a larger elongation continues, and when heat treated for 1 hour at 200°C to 400°C, the breaking elongation of SUS 304L remains at 1.9% or less, while that of SUS 304H is 2.0% or more throughout the entire range.

[0067] Thus, it is presumed that the fact that SUS 304H exhibits a larger breaking elongation after heat treatment than SUS 304L is related to the phenomenon seen in Figure 4, where SUS 304H provides higher crimp strength over a wider range of tensile strength. Furthermore, it is also confirmed from Table 2 that regardless of whether SUS 304H or SUS 304L is used, the electrical resistance of the resulting electric wire conductor is kept below 660 mΩ / m under all heat treatment conditions.

[0068] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0069] The above-described configuration of the flat electric wire can be applied to the case where any electric wire conductor other than the electric wire conductor according to the embodiment of the present disclosure is used. For example, even when a conventionally used copper alloy wire such as a Cu-Sn alloy wire is used, the conductor cross-sectional area of ​​0.32 mm 2 By arranging thin electric conductors having a diameter of less than 1 mm in parallel, it is possible to obtain the effect of reducing the diameter of the electric conductors and improving the strength. That is, in an insulated electric wire including a plurality of electric conductors, the insulated electric wire can be configured as follows, with the objective of ensuring the strength of the electric wire when the diameter of the electric conductors is reduced.

[0070] Conductor cross-sectional area is 0.32 mm 2A single wire conductor of less than 100 mm is arranged in parallel. The outer periphery of each of the electric wire conductors is covered with an insulating covering to form a covering portion, An insulated wire, wherein the covering portions are connected to each other by connecting portions that are integral with the insulating covering of the covering portions.

[0071] In the insulated electric wire, it is preferable that the distance between at least one pair of adjacent two of the electric conductors is 0.2 mm or more and 1.2 mm or less. It is particularly preferable that the distance is 1.0 mm or less. In addition, the above-described configurations can be suitably applied to the configuration of the flat electric wire. [Explanation of symbols]

[0072] 1. Insulated wire 2 Flat Wire 10 Electrical Wire Conductors 11 Core Wire 12 Copper coating layer 20 Insulation coating 25 Connecting part 30 Covering section d Distance between conductors

Claims

1. A solid core wire made of stainless steel; A copper coating layer is made of copper or a copper alloy and coats the outer periphery of the core wire. Conductor cross-sectional area is 0.13 mm ２ is less than The electrical resistance is 660 mΩ / m or less, The tensile strength is 950 MPa or more and 1080 MPa or less, The breaking elongation is 1.5% or more, An electric wire conductor used in a solid wire state.

2. In the cross section of the electric wire conductor, The hardness of the core wire is 650 Hv or more and 750 Hv or less, The conductor according to claim 1 , wherein the copper coating layer has a hardness of 80 Hv or more and 120 Hv or less.

3. The conductor according to claim 1 or 2, wherein the core wire has a tensile strength of 2400 MPa or more and 2800 MPa or less.

4. 4. The electric wire conductor according to claim 1, wherein the stainless steel constituting the core wire has a breaking elongation of 1.7% or more when heat treated at a temperature of 150° C. or more and 400° C. or less for one hour.

5. The conductor according to any one of claims 1 to 4, and an insulating coating covering an outer periphery of the electric conductor.

6. A plurality of the electric wire conductors are arranged in parallel, The outer periphery of each of the electric wire conductors is covered with the insulating covering to form a covering portion, The insulated wire according to claim 5 , wherein the covering portions are connected to each other by connecting portions that are integral with the insulating covering of the covering portions.

7. 7. The insulated wire according to claim 6, wherein a distance between at least one pair of adjacent conductors is 0.2 mm or more and 1.2 mm or less.

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