Method for manufacturing ultrafine copper alloy wire, ultrafine copper alloy wire, and cable

Abstract

This invention provides a method for manufacturing ultrafine copper alloy wires that are highly conductive and high-strength, at a low cost. It also provides ultrafine copper alloy wires with high conductivity and high strength obtained by this low-cost manufacturing method, and cables having such ultrafine copper alloy wires. [Solution] An ultrafine copper alloy wire 11 containing 1% by mass or more of silver and having an outer diameter of 0.10 mm or less is manufactured by a casting process in which molten copper alloy is cast to produce a wire-shaped casting material, a primary wire drawing process in which the casting material is drawn to produce a drawn wire, an intermediate annealing process in which the drawn wire produced in the primary wire drawing process is annealed, a secondary wire drawing process in which the drawn wire produced in the intermediate annealing process is further drawn to produce a small-diameter drawn wire, and an electro-annealing process in which the small-diameter drawn wire is electro-annealed.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an ultra-fine copper alloy wire, an ultra-fine copper alloy wire, and a cable.

Background Art

[0002] Conventionally, for example, in cables used in medical devices such as endoscopes having a portion to be inserted into the human body and portable electronic devices that require miniaturization, ultra-fine copper alloy wires are used as conductors. The ultra-fine copper alloy wire is desired to have an ultra-fine diameter and high conductivity. In addition, the ultra-fine copper alloy wire also needs to have high strength so that it does not break easily.

[0003] Patent Document 1 describes a multi-core cable including a plurality of thick-diameter shielded wires and thin-diameter shielded wires, a plurality of insulated wires, a holding coil for bundling these wires, a collective shield layer covering the periphery of the holding coil, and a cable jacket covering the periphery of the collective shield layer. The collective shield layer is formed by single-layer braiding a plurality of tin-plated soft copper alloy wires having a conductor diameter of 0.03 mm.

[0004] Patent Document 2 describes a composite cable including a cable core having a plurality of wires, a shield layer covering the outer periphery of the cable core, and a sheath covering the outer periphery of the shield layer, and using a semi-rigid copper alloy wire as a metallic element wire of the shield layer. This metallic element wire has an outer diameter of 0.03 mm or more and less than 0.16 mm, a tensile strength of 350 MPa or more and 500 MPa or less, and a conductivity of 85% IACS or more.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] Ultra-fine copper alloy wires are manufactured through a casting process, in which molten copper alloy is cast to produce a wire-shaped casting, and a wire drawing process, in which the casting is drawn to produce a wire. In order to produce highly conductive and high-strength ultra-fine copper alloy wires, there is a manufacturing method that includes a deposition heat treatment process in the middle of the wire drawing process. The deposition heat treatment process is a process in which additive elements added to copper as components of the copper alloy are subjected to heat treatment at approximately 450°C for approximately 5 hours. However, this manufacturing method requires a long deposition heat treatment process of approximately 5 hours, which has the problem of poor productivity and high manufacturing costs for ultra-fine copper alloy wires.

[0007] Therefore, the present invention aims to provide a method for manufacturing ultrafine copper alloy wires that are highly conductive and high-strength, at low cost. Furthermore, the objective is to provide highly conductive and high-strength ultrafine copper alloy wires obtained by this low-cost manufacturing method, and cables having such ultrafine copper alloy wires. [Means for solving the problem]

[0008] The present invention aims to solve the above problems and provides a method for manufacturing a copper alloy wire containing 1% by mass or more of silver and having an outer diameter of 0.10 mm or less, comprising: a casting step of casting molten copper alloy to produce a wire-shaped casting material; a primary drawing step of drawing the casting material to produce a drawn wire material; an intermediate annealing step of annealing the drawn wire material drawn in the primary drawing step; a secondary drawing step of further drawing the drawn wire material annealed in the intermediate annealing step to produce a small-diameter drawn wire material; and an electro-annealing step of electro-annealing the small-diameter drawn wire material.

[0009] Furthermore, the present invention aims to solve the above problems by providing an ultrafine copper alloy wire obtained by the above-described method for manufacturing ultrafine copper alloy wires, having a tensile strength of 600 MPa or more and 800 MPa or less, and an electrical conductivity of 90% IACS or more.

[0010] Furthermore, the present invention aims to solve the above problems by providing an ultrafine copper alloy wire having an outer diameter of 0.03 mm or more and 0.10 mm or less, containing 1% by mass or more of silver, having a tensile strength of 600 MPa or more and 800 MPa or less, an electrical conductivity of 90% IACS or more, and an elongation at break of 1.0% or more and 3.0% or less.

[0011] Furthermore, the present invention aims to solve the above-mentioned problems by providing a cable having the above-mentioned ultra-fine copper alloy wire as a shielding strand. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a method for manufacturing ultrafine copper alloy wires that are highly conductive and high-strength at low cost. Furthermore, this low-cost manufacturing method can provide highly conductive and high-strength ultrafine copper alloy wires, as well as cables having these ultrafine copper alloy wires. [Brief explanation of the drawing]

[0013] [Figure 1] (a) is a cross-sectional view perpendicular to the longitudinal direction of a cable using the ultrafine copper alloy wire according to this embodiment. (b) is a cross-sectional view of the first wire. (c) is a cross-sectional view of the second wire. [Figure 2] This is a cross-sectional view of an ultrafine copper alloy wire manufactured by the manufacturing method of this embodiment. [Figure 3] This is a flowchart showing a method for manufacturing ultra-fine copper alloy wire. [Figure 4] This graph shows the relationship between annealing time, tensile strength, and electrical conductivity when the annealing temperature in the intermediate annealing process is set to 800°C. [Figure 5] This is a diagram showing an example of the configuration of the main parts of an electrolytic annealing apparatus used for electrolytic annealing. [Figure 6](a) is a graph showing the relationship between the applied voltage in the energization annealing process and the tensile strength of the ultra-fine copper alloy wire after energization annealing. (b) is a graph showing the relationship between the applied voltage in the energization annealing process and the conductivity of the ultra-fine copper alloy wire after energization annealing.

Embodiments for Carrying Out the Invention

[0014] [Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0015] (Configuration of Cable) FIG. 1(a) is a cross-sectional view showing a cross-section perpendicular to the longitudinal direction of a cable 1 in which an ultra-fine copper alloy wire according to the present embodiment is used. The cable 1 is used, for example, as internal wiring of a small industrial robot or a medical cable such as an endoscope.

[0016] The cable 1 includes a cable core 10 having a plurality of first electric wires 2 and a plurality of second electric wires 3, a tape member 4 spirally wound around the cable core 10, a shield layer 5 provided so as to cover the outer periphery of the tape member 4, a sheath 6 provided so as to cover the outer periphery of the shield layer 5, and a tensile strength fiber 7 disposed at the center of the cable 1. As this tensile strength fiber 7, for example, one made of aramid fiber can be used. Note that the cable core 10 may be composed only of the first electric wires 2, or may be composed only of the second electric wires 3. Further, the cable core 10 may include a twisted pair formed by twisting a pair of insulated electric wires.

[0017] FIG. 1(b) is a cross-sectional view of the first electric wire 2. The first electric wire 2 is an insulated electric wire having a conductor 21 and an insulator 22 provided so as to cover the periphery of the conductor 21. In the present embodiment, the first electric wire 2 is used as a power supply line for supplying power to an electronic component. In the example shown in FIG. 1(a), a structure in which four first electric wires 2 are arranged around the tensile strength fiber 7 is shown, but the number and arrangement of the first electric wires 2 are not limited to this.

[0018] The conductor 21 of the first electric wire 2 is a stranded wire made by twisting together multiple metal strands 211. As the metal strands 211, for example, copper alloy wire such as Cu-Ag alloy can be used. As the insulator 22, for example, a fluororesin such as PFA (perfluoroalkyl vinyl ether copolymer) can be suitably used.

[0019] Figure 1(c) is a cross-sectional view of the second wire 3. The second wire 3 is a coaxial cable having an inner conductor 31, an inner insulator 32 provided to cover the inner conductor 31, an outer conductor 33 provided to cover the inner insulator 32, and an outer insulator 34 provided to cover the outer conductor 33. In this embodiment, the second wire 3 is used as a signal line for signal transmission. In the example shown in Figure 1(a), eight second wires 3 are arranged around four first wires 2, but the number and arrangement of the second wires 3 are not limited to this.

[0020] The internal conductor 31 of the second electric wire 3 is a stranded wire made by twisting together multiple metal strands 311. The external conductor 33 is a horizontally wound shield made by spirally winding multiple metal strands 331 around the internal insulator 32. Alternatively, multiple metal strands 331 may be braided together in a grid pattern, and the external conductor 33 may be a braided shield. For the metal strands 311 and 331 used for the internal conductor 31 and external conductor 33 of the second electric wire 3, for example, copper alloy wire such as Cu-Ag alloy can be used. For the internal insulator 32 and external insulator 34, for example, fluororesin such as PFA can be suitably used.

[0021] The tape member 4 is spirally wrapped around the cable core 10. The tape member 4 may be a resin tape made of a resin such as polyimide or polyester, or a metal foil tape in which a metal foil made of copper or aluminum is laminated to the resin tape.

[0022] The shield layer 5 consists of a horizontally wound shield, which is formed by spirally winding shield wires 51 around the outer circumference of the tape member 4. Alternatively, multiple shield wires 51 may be braided together in a grid pattern, making the shield layer 5 a braided shield. However, when the shield layer 5 is a horizontally wound shield, friction between the shield wires 51 when the cable 1 is bent can be suppressed, thereby improving bending resistance.

[0023] The sheath 6 is made of a fluororesin such as PFA, and its thickness is 0.06 mm or more and less than 0.20 mm. The outer diameter of the sheath 6, i.e., the outer diameter D1 of the cable 1, is 1.0 mm or more and 2.0 mm or less. The outer diameter of the cable 1 can be determined based on the test method specified in JISC3005.

[0024] (Structure and manufacturing method of ultra-fine copper alloy wire) Next, the method for manufacturing the ultrafine copper alloy wire in this embodiment will be described. Figure 2 is a cross-sectional view of the ultrafine copper alloy wire 11 manufactured by the manufacturing method of this embodiment. The ultrafine copper alloy wire 11 has a wire body 111 and a plating layer 112 that covers the outer surface 111a of the wire body 111. The wire body 111 is made of a copper alloy mainly composed of copper (Cu) and containing 1% by mass or more and 3% by mass or less of silver (Ag). Outer diameter D of the ultrafine copper alloy wire 11 11 The thickness is between 0.03 mm and 0.10 mm. 12 The thickness is between 0.5 μm and 1.5 μm. In this embodiment, the plating layer 112 is a silver plating layer.

[0025] This ultra-fine copper alloy wire 11 is used as the shielding strand 51 of the shielding layer 5 in the cable 1. However, the ultra-fine copper alloy wire 11 may also be used as the metal strand 331 of the outer conductor 33 in the second electric wire 3. Alternatively, the ultra-fine copper alloy wire 11 may be used as the metal strand 211 of the conductor 21 in the first electric wire 2 or as the metal strand 311 of the inner conductor 31 in the second electric wire 3.

[0026] Figure 3 is a flowchart showing the manufacturing method of the ultrafine copper alloy wire 11. The manufacturing method of the ultrafine copper alloy wire 11 includes a casting process (step S1), a primary wire drawing process (step S2), an intermediate annealing process (step S3), a secondary wire drawing process (step S4), a plating process (step S5), and an electrical annealing process (step S6). In this embodiment, the secondary wire drawing process (step S4) includes a first-stage secondary wire drawing process (step S41) and a second-stage secondary wire drawing process (step S42), and a plating process (step S5) is performed between the first-stage secondary wire drawing process (step S41) and the second-stage secondary wire drawing process (step S42). In other words, in the secondary wire drawing process (step S4), wire drawing is performed before and after the plating process.

[0027] In the casting process, molten copper alloy is cast to produce a linear casting. This molten metal is, for example, a mixture of 2% by mass of silver and copper. The casting method is not particularly limited, but continuous casting methods such as twin-roll casting, twin-belt casting, belt-and-wheel casting, upcasting, and downcasting can be suitably used.

[0028] In the primary wire drawing process, the cast material created in the casting process is subjected to wire drawing to produce drawn wire. This wire drawing process is, for example, a drawing process using multiple dies. The diameter of the cast material before wire drawing in the primary wire drawing process is, for example, 8.0 mm. The diameter of the drawn wire after wire drawing is, for example, 0.9 mm.

[0029] In the intermediate annealing process, the drawn wire material, which has been drawn in the primary drawing process, is annealed to create fine crystal grains within the wire material and to reduce the processing strain that occurred in the primary drawing process. This increases the conductivity that was reduced by the processing strain. The annealing temperature in the intermediate annealing process is between 700°C and 900°C, and the annealing time is, for example, 10 to 45 seconds. By performing this relatively short intermediate annealing process, the deposition of silver in the drawn wire material is suppressed.

[0030] Figure 4 is a graph showing the relationship between annealing time (heat treatment time), tensile strength, and electrical conductivity when the annealing temperature in the intermediate annealing process is 800°C. As shown in this graph, when the heat treatment time is between 10 seconds and 45 seconds, the electrical conductivity becomes 93% IACS or higher, and when it is between 20 seconds and 45 seconds, the electrical conductivity becomes 94% IACS or higher. Furthermore, when the heat treatment time is extended to 45 seconds or more, the electrical conductivity gradually decreases. On the other hand, the tensile strength gradually decreases until the heat treatment time is about 28 seconds, and then becomes almost constant above 28 seconds. Note that the flexibility of the drawn wire gradually increases as the heat treatment time increases, or in other words, as the tensile strength decreases. The desirable range for annealing time when the annealing temperature is 800°C is 28 to 36 seconds.

[0031] Figure 4 shows photographs of cross-sections of the drawn wire at heat treatment times T0 (0 seconds), T1 (28 seconds), and T2 (84 seconds). In these photographs, the left-right direction in the drawing corresponds to the longitudinal direction of the drawn wire. The dark, striped areas extending horizontally in the photographs at T0 and T1 represent the Ag-rich phase, which has a high proportion of silver. As shown in these photographs, as the heat treatment progresses, fine crystal grains are formed up to T1, and as the heat treatment time increases further, the crystal grains grow and become coarser. Also, between T0 and T1, the internal stress generated in the drawn wire during the primary drawing process is relieved, reducing hardness and improving ductility.

[0032] In the secondary wire drawing process (first-stage secondary wire drawing process and second-stage secondary wire drawing process), the drawn wire material annealed in the intermediate annealing process is further drawn to produce a small-diameter drawn wire material. In the first-stage secondary wire drawing process, the wire diameter is reduced to, for example, 0.6 mm. In the second-stage secondary wire drawing process, the wire diameter is reduced to, for example, 0.03 mm. In the first-stage and second-stage secondary wire drawing processes, the wire material is subjected to cold drawing by, for example, a drawing process using multiple dies.

[0033] In the plating process, a plating layer is formed on the surface of the base material between the intermediate annealing process and the electro-annealing process, more specifically between the first-stage secondary wire drawing process and the second-stage secondary wire drawing process. This base material is the wire drawn in the first-stage secondary wire drawing process after being annealed in the intermediate annealing process. However, the plating process may be performed after the intermediate annealing process and before the secondary wire drawing process, or after the secondary wire drawing process and before the electro-annealing process. The plating layer formed in the plating process is a silver plating layer corresponding to the plating layer 112 of the ultra-fine copper alloy wire 11 shown in Figure 2.

[0034] In the electro-annealing process, electro-annealing is performed on a small-diameter drawn wire that has been drawn in the secondary drawing process, or more specifically, a small-diameter drawn wire that has been drawn in the secondary drawing process and has a plating layer formed in the plating process. In this embodiment, electro-annealing is performed by applying a voltage of 20V to 21V to the small-diameter drawn wire for a time of 0.2 seconds to 0.4 seconds, with the aim of improving conductivity and ensuring high strength characteristics.

[0035] Figure 5 is a diagram showing an example of the configuration of the main parts of an energized annealing apparatus 8 that performs energized annealing. The energized annealing apparatus 8 includes a first power supply sheave 81 and a second power supply sheave 82, a guide pulley 83, a power supply sheave temperature holding tube 84 positioned between the first power supply sheave 81 and the second power supply sheave 82, a cooling tube 85 positioned between the second power supply sheave 82 and the guide pulley 83, and a DC power supply 86 that supplies power to the first power supply sheave 81 and the second power supply sheave 82. The small diameter drawn wire 110 is wrapped around the first power supply sheave 81, the second power supply sheave 82, and the guide pulley 83 and moves in the direction of the arrows shown in the figure.

[0036] As the thin-diameter drawn wire 110 moves between the first power supply sheave 81 and the second power supply sheave 82, a current corresponding to the applied voltage from the DC power supply 86 flows longitudinally, and it is heated by Joule heating to a high temperature. Subsequently, the temperature decreases between the second power supply sheave 82 and the guide pulley 83, and it becomes an ultra-fine copper alloy wire 11. The applied voltage applied between the first power supply sheave 81 and the second power supply sheave 82 is 20V or more and 21V or less. The time it takes for the thin-diameter drawn wire 110 to move between the first power supply sheave 81 and the second power supply sheave 82 (energy annealing time) is 0.2 seconds or more and 0.4 seconds or less.

[0037] Figure 6(a) is a graph showing the relationship between the applied voltage during the current annealing process and the tensile strength of the ultrafine copper alloy wire 11 after current annealing. As shown in this graph, the tensile strength of the ultrafine copper alloy wire 11 decreases as the applied voltage increases. Figure 6(b) is a graph showing the relationship between the applied voltage during the current annealing process and the conductivity of the ultrafine copper alloy wire 11 after current annealing. As shown in this graph, the conductivity of the ultrafine copper alloy wire 11 gradually increases as the applied voltage increases from 0V to about 20V, and remains almost constant from 20V to about 23V. Thus, with respect to the applied voltage during the current annealing process, the tensile strength and conductivity of the ultrafine copper alloy wire 11 are inversely related.

[0038] The above applied voltage range (20V to 21V) was determined to be a range that does not excessively reduce tensile strength while obtaining high conductivity. To elaborate on this point, when heat is applied during the energized annealing process, a process called "recovery" occurs as a preliminary step to recrystallization, in which the strain generated by the wire drawing process in the secondary wire drawing process is released without causing a major change in the metal structure. By capturing this recovery process, it is possible to remove the strain without significantly reducing strength and to increase conductivity.

[0039] In other words, in this embodiment, high strength and high conductivity are obtained by ending the heat treatment in the recovery process during the energized annealing process. The ultrafine copper alloy wire 11 according to this embodiment has a tensile strength of 600 MPa to 800 MPa, an conductivity of 90% IACS or higher, and an elongation of 1.0% to 3.0%. Here, "tensile strength" and "elongation" refer to the "tensile strength" and "elongation at break" determined by the test method specified in JIS Z 2241.

[0040] (Effects of the embodiment) According to the embodiments described above, by performing electric annealing on the small-diameter drawn wire obtained through the primary wire drawing process, intermediate annealing process, and secondary wire drawing process, an ultra-fine copper alloy wire 11 with high tensile strength and conductivity and an outer diameter of 0.10 mm or less can be obtained. Furthermore, the time required for electric annealing is short, and it can be performed in line in parallel with the secondary wire drawing process, thereby suppressing manufacturing costs.

[0041] (Summary of the embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals and other symbols from the embodiments. However, the reference numerals in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0042] [1] A method for manufacturing a copper alloy wire containing 1% by mass or more of silver and having an outer diameter of 0.10 mm or less, comprising: a casting step of casting molten copper alloy to produce a wire-shaped casting material; a primary drawing step of drawing the casting material to produce a drawn wire material; an intermediate annealing step of annealing the drawn wire material drawn in the primary drawing step; a secondary drawing step of further drawing the drawn wire material annealed in the intermediate annealing step to produce a fine-diameter drawn wire material; and an electro-annealing step of electro-annealing the fine-diameter drawn wire material.

[0043] [2] The method for manufacturing an ultrafine copper alloy wire (11) according to [1], wherein in the energizing annealing step, a voltage of 20V or more and 21V or less is applied to the thin diameter drawn wire for a time of 0.2 seconds or more and 0.4 seconds or less.

[0044] [3] A method for manufacturing an ultrafine copper alloy wire (11) according to [1], comprising a plating step between the intermediate annealing step and the energized annealing step, wherein a plating layer (112) is formed on the surface of the base material.

[0045] [4] A method for manufacturing an ultrafine copper alloy wire (11) as described in [3] above, wherein the wire drawing process is performed before and after the plating process in the secondary wire drawing process.

[0046] [5] An ultrafine copper alloy wire (11) obtained by a method for manufacturing an ultrafine copper alloy wire (11) as described in any of [1] to [4] above, having a tensile strength of 600 MPa or more and 800 MPa or less, and an electrical conductivity of 90% IACS or more.

[0047] [6]Outer diameter (D 11 An ultrafine copper alloy wire (11) with a diameter of 0.03 mm or more and 0.10 mm or less, containing 1 mass% or more of silver, having a tensile strength of 600 MPa or more and 800 MPa or less, an electrical conductivity of 90% IACS or more, and an elongation at break of 1.0% or more and 3.0% or less.

[0048] [7] The ultrafine copper alloy wire (11) according to [6] above, comprising a wire body (111) made of a copper alloy containing 1% by mass or more and 3% by mass or less of silver, and a silver plating layer (112) formed on the surface of the wire body (111).

[0049] [8] A cable (1) having the ultrafine copper alloy wire (11) described in [6] or [7] above as a shielding strand (51).

[0050] Although embodiments of the present invention have been described above, these embodiments do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. [Explanation of symbols]

[0051] 1…Cable 51…Shielded strand 110...Small diameter drawn wire material 111...Wire strand body 112…Plating layer D 11 ...outer diameter

Claims

1. A method for manufacturing a copper alloy wire containing 1% by mass or more of silver and having an outer diameter of 0.10 mm or less, The casting process involves casting molten copper alloy to produce a linear casting material, A primary wire drawing process is performed on the aforementioned cast material to produce a drawn wire, An intermediate annealing step is performed to anneal the drawn wire material that has been drawn in the primary wire drawing step, A secondary drawing process is performed to produce a small-diameter drawn wire by further drawing the drawn wire annealed in the intermediate annealing process, An energized annealing step is performed on the aforementioned small-diameter drawn wire, A method for manufacturing ultra-fine copper alloy wires equipped with [a specific feature / feature].

2. In the energizing annealing process, a voltage of 20V to 21V is applied to the small diameter drawn wire for a period of 0.2 seconds to 0.4 seconds. A method for manufacturing an ultrafine copper alloy wire according to claim 1.

3. Between the intermediate annealing step and the current-induced annealing step, there is a plating step in which a plating layer is formed on the surface of the base material. A method for manufacturing an ultrafine copper alloy wire according to claim 1.

4. In the aforementioned secondary wire drawing process, wire drawing is performed before and after the aforementioned plating process. A method for manufacturing an ultrafine copper alloy wire according to claim 3.

5. Obtained by the method for manufacturing ultrafine copper alloy wire according to any one of claims 1 to 4, The tensile strength is between 600 MPa and 800 MPa. The conductivity is 90% IACS or higher. Ultra-fine copper alloy wire.

6. An ultra-fine copper alloy wire with an outer diameter of 0.03 mm or more and 0.10 mm or less, Contains 1% or more by mass of silver, Tensile strength of 600 MPa or more and 800 MPa or less, Conductivity of 90% IACS or higher, The elongation at break is between 1.0% and 3.0%. Ultra-fine copper alloy wire.

7. The wire has a main body made of a copper alloy containing 1% to 3% by mass of silver, and a silver plating layer formed on the surface of the main body. The ultra-fine copper alloy wire according to claim 6.

8. The ultrafine copper alloy wire described in claim 6 or 7 is used as the shielding wire. cable.

Images