Copper or copper alloy conducting wire and method for manufacturing same

Abstract

A copper or copper alloy conducting wire composed of copper or a copper alloy, wherein in an X-ray diffraction chart obtained when X-rays are irradiated from a direction orthogonal to the length direction of the conducting wire, the peak intensity of the (111) plane of copper relative to the sum of the peak intensity of the (111) plane of copper and the peak intensity of the (220) plane of copper is 50% or more.

Description

Copper or copper alloy conductive wire and method for manufacturing the same

[0001] The present invention relates to a copper or copper alloy conductive wire and a method for manufacturing the same.

[0002] Conventionally, various conductive wires have been used in electronic devices and the like. In recent years, along with the miniaturization of electronic devices, high-density mounting of various circuit boards used therein has been demanded. Various conductive wires are also used in various circuit boards such as various mounting substrates and IC package substrates. Conductive wires used for various circuit boards such as various mounting substrates and IC package substrates may be required to have good workability and hardness.

[0003] Patent Document 1 describes a copper alloy wire used for coils such as micro speakers. For the copper alloy wire described in Patent Document 1, first, an ingot of copper alloy obtained by casting molten metal is drawn. Then, the obtained wire is heat-treated to produce the copper alloy wire.

[0004] Patent Document 2 describes a lead wire for an inspection device. The lead wire for an inspection device described in Patent Document 2 is manufactured by drawing a copper alloy wire having a predetermined diameter and then performing tension annealing, which is a heat treatment.

[0005] International Publication No. WO2018 / 100919, Japanese Unexamined Patent Publication No. 2019-143981

[0006] Along with the miniaturization of electronic devices, the diameter reduction of conductive wires has been progressing. When the diameter of a conductive wire is reduced, the workability of the conductive wire tends to decrease. For example, when processing into a contact probe, the elongation decreases along with the diameter reduction, which is considered to make wire breakage more likely to occur and deteriorate workability.

[0007] A main object of the present invention is to provide a copper or copper alloy conductive wire that has good workability while maintaining Vickers hardness even when the diameter is reduced, and a method for manufacturing the same.

[0008] The present invention provides a copper or copper alloy conductor, wherein, in the diffraction chart of the X-ray diffraction obtained when X-rays are irradiated from a direction perpendicular to the longitudinal direction of the conductor, the ratio of the peak intensity of the copper (111) plane to the sum of the peak intensities of the copper (111) plane and the copper (220) plane is 50% or more.

[0009] To solve the above problems, according to one aspect of the present invention, a method for manufacturing a copper or copper alloy wire is provided, comprising the steps of: preparing a wire made of copper or a copper alloy; and twisting the wire using a die to obtain a conductor, wherein in the diffraction chart of the X-ray diffraction obtained when X-rays are irradiated from a direction perpendicular to the longitudinal direction of the conductor, the peak intensity of the copper (111) plane is 50% or more of the sum of the peak intensity of the copper (111) plane and the peak intensity of the copper (220) plane.

[0010] According to the present invention, it is possible to provide copper or copper alloy wires that maintain Vickers hardness while having good workability, even when the diameter is reduced.

[0011] Figure 1 is a schematic diagram illustrating the X-ray diffraction method. Figure 2 is a flowchart showing a method for manufacturing a conductive wire according to an embodiment of the present invention. Figure 3 is a schematic diagram showing the configuration of a processing apparatus having a die for performing a twisting process. Figure 4 is a schematic diagram showing the configuration of a processing apparatus having a blade for performing a twisting process.

[0012] The following describes a conductor (referred to as "copper or copper alloy conductor" in the claims) and a method for manufacturing the conductor according to one embodiment of the present invention. The conductor and the method for manufacturing the conductor are not limited to the embodiments shown below. In this specification, the "~" indicating a numerical range includes both an upper and lower limit.

[0013] (Conductor composition) The conductor (copper or copper alloy conductor) of this embodiment is composed of copper or a copper alloy. "Composed of copper" means that it may contain unavoidable impurities. The copper content in the copper conductor is appropriately selected according to the desired properties of the conductor, but 99.9% by mass or more is preferred.

[0014] Examples of unavoidable impurities include iron, tin, beryllium, zinc, nickel, magnesium, aluminum, titanium, zirconium, indium, silicon, and phosphorus. The content of unavoidable impurities in copper wires is preferably 0.1% by mass or less, and more preferably 0.01% by mass or less. If the content of unavoidable impurities exceeds 0.1% by mass, the tensile strength and other properties may decrease.

[0015] "Composed of a copper alloy" means that it may contain unavoidable impurities. In this embodiment, the copper alloy contains copper and other metals, and may further contain unavoidable impurities. The copper content in the copper alloy wire is appropriately selected according to the desired properties of the wire, but is preferably in the range of 70.0 to 99.9 mass%, and more preferably in the range of 76.0 to 99.7 mass%. When the copper content is within this range, it is easier to bring the plastic elongation of the wire within the desired range. Examples of other metals include silver, tin, titanium, magnesium, aluminum, silicon, phosphorus, chromium, iron, manganese, cobalt, nickel, zinc, zirconium, niobium, and indium. The content of other metals in the copper alloy wire is preferably in the range of 0.1 to 30.0 mass%, and more preferably in the range of 0.3 to 24.0 mass%. Examples of unavoidable impurities and their content are as described above.

[0016] The diameter of the conductor is selected appropriately depending on the application of the conductor, but it is preferably within the range of 0.01 to 0.60 mm. Note that if the cross-sectional shape of the conductor is not circular, the diameter of the conductor refers to the diameter of the circumscribed circle of the conductor. When the diameter of the conductor is within this range, for example, when used in electrical characteristic testing equipment or probe pins, the conductors can be arranged at a narrow pitch.

[0017] In the diffraction chart of X-ray diffraction obtained when X-rays are irradiated from a direction perpendicular to the length direction of the conductor, the ratio of the peak intensity of the (111) plane of copper to the sum of the peak intensities of the (111) plane and the (220) plane of copper is 50% or more, preferably 55.0% or more, and more preferably 70% or more. Furthermore, the ratio of the peak intensity of the (111) plane of copper is preferably 95% or less, and more preferably 90% or less. Thus, making the ratio of the peak intensity of the (111) plane of copper 50% or more means that the crystal orientation of the copper crystals is oriented in a predetermined direction. This results in good elongation (plastic elongation) of the conductor, as described later. Note that the method for making the ratio of the peak intensity of the (111) plane of copper 50% or more includes the twisting process described later.

[0018] In the diffraction chart of X-ray diffraction obtained when X-rays are irradiated from a direction perpendicular to the length direction of the conductor, the ratio of the peak intensity of the (220) plane of copper to the sum of the peak intensities of the (111) plane and the (220) plane of copper is less than 50%, preferably 45% or less, and more preferably 30% or less. Furthermore, the ratio of the peak intensity of the (220) plane of copper is preferably 10% or more, and more preferably 5% or more. In order to make the ratio of the peak intensity of the (220) plane of copper less than 50%, it is preferable to perform the twisting process described later.

[0019] In the diffraction chart of X-ray diffraction obtained when X-rays are irradiated from a direction perpendicular to the longitudinal direction of the wire, the ratio of the peak intensity of the (111) plane of copper to the sum of the peak intensities of the (111) plane and the (220) plane of copper differs significantly before and after twisting. Before twisting, wires can be drawn or rolled to obtain predetermined dimensions and improve tensile strength and hardness, but it is known that the structure of the copper base material undergoes a textured structure toward a specific crystal orientation. Specifically, by reducing the diameter to a desired diameter through processes such as wire drawing, the ratio of the peak intensity of the (111) plane of copper in the diffraction chart of X-ray diffraction obtained when X-rays are irradiated from a direction perpendicular to the longitudinal direction of the wire becomes smaller than the ratio of the peak intensity of the (220) plane of copper. On the other hand, in wires after twisting, the ratio of the peak intensity of the (111) plane of copper can be made larger than the ratio of the peak intensity of the (220) plane of copper. Thus, by performing this twisting process, the degree of density of the texture in the conductor reverses compared to before processing, which is thought to result in improved plastic elongation, as described later.

[0020] Here, the ratio of the peak intensity of the (110) plane of copper and the ratio of the peak intensity of the (220) plane of copper can be determined as follows. Figure 1 is a schematic diagram illustrating the X-ray diffraction method. First, as shown in Figure 1, X-rays are irradiated from a direction perpendicular to the length direction of the wire 130 using an X-ray rotating pair cathode generator (Ag source) 100 in the concentrated beam method, and the diffraction peaks are detected by the X-ray detector 120 in the 2θ-θ method. It is preferable to rotate the wire 130 to obtain the average diffraction peak of the entire wire 130. Next, the phase of the diffraction peak is identified, and the intensity (height) of the (111) plane of copper and the (220) plane of copper are determined, respectively. Then, the ratio of the peak intensity of the (110) plane of copper and the ratio of the peak intensity of the (220) plane of copper to the sum of the peak intensity of the (111) plane of copper and the peak intensity of the (220) plane of copper are calculated. In other words, the peak intensities of the (110) plane and the (220) plane of copper are ratios to the sum of the peak intensities of the (111) plane and the (220) plane of copper, with the sum set to 100. X-ray diffraction by the 2θ-θ method is measured using, for example, a test wire 50 mm in length, while rotating the test wire. However, the size of the test wire is not limited to the shape described above; the test wire just needs to be large enough to be placed in the X-ray diffractometer.

[0021] The wire drawing pitch in the twisting process of the conductor is not particularly limited, but is preferably 2.0 mm or less. Here, "wire drawing pitch" refers to the distance that a wire with unavoidable shallow scratches that occur parallel to the longitudinal direction during the wire drawing process (described later) advances in the longitudinal direction when it completes one rotation after twisting. If the wire drawing pitch is 2.0 mm or less, the diffraction peak intensity falls within the desired range and plastic elongation is improved.

[0022] In this embodiment, the Vickers hardness of the conductor's cross-section is in the range of 100 to 350 HV. Here, "cross-section" refers to the cross-section in a direction perpendicular to the longitudinal direction of the conductor. When the Vickers hardness is within the above range, it becomes easier to use for probe pins and the like. Also, the ratio of the Vickers hardness of the center to the Vickers hardness of the outer circumference of the conductor's cross-section is in the range of 0.90 to 1.10. Here, "cross-section" refers to the cross-section in a direction perpendicular to the longitudinal direction of the conductor. "Center" refers to the region near the center of the conductor, for example, the region on the center side when the radius of the conductor is divided in two from the center of the conductor. The center is the centroid of the conductor's cross-section. Also, "outer circumference" refers to the region near the circumferential surface of the conductor, for example, the region from the outer circumference of the conductor to a depth of half the radius of the conductor. Furthermore, when the Vickers hardness is within the above range, if the tip shape of the conductor is flat, it will wear uniformly, and if the tip shape of the conductor is needle-shaped, the tip will not easily be crushed. In this specification, Vickers hardness refers to values ​​measured in accordance with JIS Z 2244-1 2020. Alternatively, hardness may be measured by nanoindentation, and a relationship of Vickers hardness, a general indicator of hardness, is known, for example, Vickers hardness = (76.2 × nanoindentation hardness) + 6.3 (Non-patent Literature 1: Metals, Vol. 78 (2008) No. 9, p. 47).

[0023] The elongation (plastic elongation) of the conductor is preferably between 1.0% and 3.0%. This elongation can be determined using a precision universal testing machine (for example, one manufactured by Shimadzu Corporation). If the elongation (plastic elongation) of the conductor is 1.0% or more, the occurrence of breakage or cracking during subsequent processes such as wire drawing, pressing, and bending can be suppressed. However, if the elongation (plastic elongation) of the conductor exceeds 3.0%, sagging is likely to occur, for example, when the conductor is cut. Plastic elongation can be measured by the following method: Divide the strain at the break of the tensile test by the strain at the 0.2% yield strength. The value obtained in this way is taken as the elongation (plastic elongation) of the conductor.

[0024] (Method for manufacturing conductors) Next, the method for manufacturing conductors will be described. Figure 2 is a flowchart of the method for manufacturing conductors according to an embodiment of the present invention.

[0025] As shown in Figure 2, the process includes a step of preparing a wire made of copper or a copper alloy (S110) (hereinafter also simply referred to as the "preparation step") and a step of twisting the wire (S120) (hereinafter also simply referred to as the "twisting step").

[0026] In the preparation step (S110), wires made of copper or a copper alloy are prepared. The composition of the wires is the same as that of the copper or copper alloy described above. The wires may be manufactured by any method, for example, by drawing or rolling wires made of a wire rod of any casting diameter using grooved rolls, or by a combination of drawing and rolling. The diameter of the wires to be prepared is preferably in the range of 0.01 to 0.60 mm.

[0027] In the twisting process (S120), the wires prepared in the preparation process are twisted. The configuration of the twisting processing apparatus is not particularly limited. Figure 3 is a schematic diagram showing an example of the configuration of the processing apparatus 200 that performs the twisting process.

[0028] As shown in Figure 3, the processing apparatus 200 has a die 230 positioned between one bobbin 210 and the other bobbin 220, with a reduction ratio of 0.5 to 25.0% of the diameter of the wire 140. The wire 140 is wound onto the other bobbin 220 while the first bobbin 210 is rotated at a constant speed in the circumferential direction of the wire 140. At this time, it is preferable that the rotation speed of the bobbin 210 relative to the transport speed is within a range in which the wire drawing pitch is 2.0 mm or less. If the reduction ratio of the die hole diameter is 0.5% or less, twisting cannot be efficiently applied to the wire, and if it is 25.0% or more, the risk of wire breakage increases. In addition, the die may be rotated as needed, and the linearity of the conductor can be adjusted by rotating the die.

[0029] When the wire is twisted, the ratio of the peak intensity of the copper (111) plane to the sum of the peak intensities of the copper (111) plane and the copper (220) plane in the X-ray diffraction chart of the wire becomes 50% or more, resulting in good plastic elongation.

[0030] (Effects) As described above, in the conductor of this embodiment, as shown in Figure 1, in the diffraction chart of X-ray diffraction when X-rays are irradiated from a direction perpendicular to the length direction of the conductor, the ratio of the peak intensity of the (111) plane of copper to the sum of the peak intensity of the (111) plane of copper and the peak intensity of the (220) plane of copper is 50% or more. Since the crystal orientation of the copper crystals is oriented in a predetermined direction, it exhibits excellent plastic elongation.

[0031] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited in any way by these examples, and the embodiments can be modified without departing from the spirit of the invention.

[0032] 1. Manufacturing of Conductors (1) The raw materials for manufacturing Conductor 1 were heated to 1000-1400°C and melted to prepare a molten metal consisting of 10% by mass of Ag and the remainder being Cu and unavoidable impurities. The molten metal was poured into a mold and cooled to room temperature within 10 minutes to cast a rod with a diameter of 12 mm. Next, the cast rod was N ２ The rod was heated at 500°C for 10 hours in a gas atmosphere. Afterward, the heated rod was drawn from a diameter of 12 mm to a diameter of 2.0 mm to produce wire. The resulting wire was then processed using N ２ The wire was heated again at 350°C for 30 hours in a gas atmosphere. After that, the reheated 2.0 mm diameter wire was drawn down to a diameter of 0.05 mm to produce conductor 1.

[0033] (2) Using the processing apparatus shown in Figure 3, which incorporates a die with a manufacturing hole diameter of 0.048 mm for the conductor 2, the conductor 1 was twisted to have a drawing pitch of 0.5 mm to produce the conductor 2.

[0034] (3) Using the processing apparatus shown in Figure 3, which incorporates a die with a manufacturing hole diameter of 0.048 mm, the wire 1 was twisted to have a drawing pitch of 1.5 mm to produce the wire 3.

[0035] (4) Instead of using a manufacturing die for the wire 4, the wire 1 was twisted using a processing device having a blade as shown in Figure 4 to manufacture the wire 4. Figure 4 is a diagram showing the configuration of the processing device having a blade. As shown in Figure 4, the processing device 300 has a pair of rotating plates (first rotating plate 311a, second rotating plate 311b) that are arranged opposite each other with the wire 140 in between. The pair of rotating plates (first rotating plate 311a, second rotating plate 311b) are connected to a motor (not shown) and are configured to rotate together at a predetermined speed in the circumferential direction of the wire 140 with the wire 140 as the central axis. The first rotating plate 311a has a first support portion 312a and a third support portion 312c for supporting the wire 140 at a predetermined height. The second rotating plate 311b has a second support portion 312b for pushing the wire 140 to a predetermined position. Each end of the support parts 312a, 312b, and 312c has a groove (not shown) for supporting the wire strand 140. First, the wire strand 140 is supported by the first support part 312a, the second support part 312b, and the third support part 312c of the processing device 300, respectively. At this time, the height and position of the first support part 312a, the second support part 312b, and the third support part 312c are adjusted so that the angle (α and β in Figure 4) between the wire strand 140 pushed in by the second support part 312b and the transport direction is 10 to 70°. The angles α and β between the wire strand 140 and the transport direction are preferably 20 to 50°, and more preferably 20 to 40°. The angles α and β may be different values, but it is preferable that they be the same value. Next, while the wire strands 140 are transported from one bobbin 350 to the other bobbin 360 at a constant speed, the rotating plates of the processing device 300 (first rotating plate 311a, second rotating plate 311b) are rotated at a constant speed in the circumferential direction of the wire strands 140. In the twisting process, the wire was twisted so that the twisting amount shown below was 20 rotations / mm. Twisting amount = rotational speed (rpm) / transport speed [mm / min]

[0036] (5) Manufacturing of conductor 5 Conductor 5 was manufactured in the same manner as conductor 1, except that a copper alloy wire containing 3.0 mass% silver was used.

[0037] (6) Production of conductive wire 6 Using the processing apparatus shown in Fig. 3 incorporating a die with a hole diameter of 0.048 mm, the conductive wire 5 was twisted to obtain a wire drawing pitch of 0.5 mm, thereby producing the conductive wire 6.

[0038] (7) Production of conductive wire 7 The conductive wire 7 was produced in the same manner as the conductive wire 1, except that a copper alloy raw wire containing 24.0 mass% of silver was used.

[0039] (8) Production of conductive wire 8 Using the processing apparatus shown in Fig. 3 incorporating a die with a hole diameter of 0.048 mm, the conductive wire 7 was twisted to obtain a wire drawing pitch of 0.5 mm, thereby producing the conductive wire 8.

[0040] (9) Production of conductive wire 9 A copper alloy raw wire containing 0.3 mass% of tin was prepared. Then, the conductive wire 9 was produced by wire drawing.

[0041] (10) Production of conductive wire 10 Using the processing apparatus shown in Fig. 3 incorporating a die with a hole diameter of 0.048 mm, the conductive wire 8 was twisted to obtain a wire drawing pitch of 0.5 mm, thereby producing the conductive wire 10.

[0042] (11) Production of conductive wire 11 A raw material was heated to 1300 to 1500°C and melted by a high-frequency melting furnace to prepare a molten material (molten metal) containing 3.2 mass% of Ti, with the balance being Cu and unavoidable impurities, and the molten material was cast into a cylindrical shape with a diameter of 15 mm. The cast material was homogenized at 900°C for 1 hour and then quenched, and a bar material with a diameter of 3 mm was obtained through hot / cold groove rolling. Then, the 3 mm bar material was subjected to solution treatment at 900°C for 10 minutes and then quenched, followed by multi-stage overaging treatment at 600°C for 3 hours, 550°C for 3 hours, 500°C for 3 hours, and 450°C for 12 hours. The bar material was drawn to a diameter of 0.1 mm to produce the conductive wire 11.

[0043] (12) Production of conductive wire 12 Using the processing apparatus shown in Fig. 3 incorporating a die with a hole diameter of 0.094 mm, the conductive wire 11 was twisted to obtain a wire drawing pitch of 1.0 mm, thereby producing the conductive wire 12.

[0044] (13) Production of conductive wire 13 A copper raw wire was prepared. Then, the conductive wire 13 was produced by wire drawing.

[0045] (14) The conducting wire 14 was manufactured by subjecting the conducting wire 13 to twisting processing using the processing apparatus shown in Fig. 3 incorporated with a die having a manufacturing hole diameter of 0.048 mm for the conducting wire 14, such that the wire drawing pitch was 0.5 mm.

[0046] The metal composition of each conducting wire and the manufacturing conditions of the conducting wires are shown in Table 1.

[0047]

[0048] 2. Various Measurements (1) Measurement of Vickers Hardness Vickers hardness was measured in accordance with JIS Z 2244-1 2020.

[0049] (2) Measurement of Plastic Elongation Plastic elongation was measured using a precision universal testing machine. Specifically, the strain at break in the tensile test is divided by the strain at 0.2% proof stress. The value obtained in this manner was taken as the elongation (plastic elongation) of the conducting wire. Plastic elongation was evaluated according to the following criteria. Evaluation Criteria ○: Plastic elongation was 1.0% or more. ×: Plastic elongation was less than 1.0%.

[0050] (3) Measurement of Peak Intensity Ratio For measurement of peak intensity, first, X-rays were irradiated from a direction orthogonal to the length direction of the conducting wire by the focused beam method, and diffraction peaks were detected by the 2θ-θ method. Next, the phases of the diffraction peaks were identified, and the intensities (heights) of the (111) plane of copper and the (220) plane of copper were obtained respectively. Next, the ratio of the peak intensity of the (110) plane of copper to the total value of the peak intensity of the (111) plane of copper and the peak intensity of the (220) plane of copper was calculated.

[0051] The metal composition of the conducting wires, the diameters of the conducting wires, and the measurement results are shown in Table 2.

[0052]

[0053] As shown in Tables 1 and 2, in the diffraction chart of X-ray diffraction when irradiated with X-rays from a direction perpendicular to the length direction of the wire, wires 2, 3, 6, 8, 10, 12, and 14, in which the ratio of the peak intensity of the copper (111) plane to the sum of the peak intensities of the copper (111) plane and the copper (220) plane was 50% or more, had the same Vickers hardness as comparative examples wires 1, 4, 5, 7, 9, 11, and 13, which were not subjected to twisting, and maintained Vickers hardness while also exhibiting good plastic elongation.

[0054] On the other hand, wires 1, 4, 5, 7, 9, 11, and 13, in which the proportion of peak strength of the (111) plane of the copper was less than 50%, exhibited poor plastic elongation. This is thought to be because they were not twisted using a die.

[0055] The conductor (copper or copper alloy conductor) of the present invention can be used, for example, in probe pins, suspension wires, medical guide wires, and the like.

[0056] 100 Rotating X-ray pair cathode generator (Ag ray source) 120 Detector 130 Conductor wire 140 Strand wire 200, 300 Processing equipment 210, 220, 350, 360 Bobbin 230 Die 311a First rotating plate 311b Second rotating plate 312a First support part 312b Second support part 312c Third support part

Claims

1. A copper or copper alloy conductor, wherein, in the diffraction chart of X-ray diffraction obtained when X-rays are irradiated from a direction perpendicular to the longitudinal direction of the conductor, the ratio of the peak intensity of the copper (111) plane to the sum of the peak intensities of the copper (111) plane and the copper (220) plane is 50% or more.

2. A copper or copper alloy wire according to claim 1, characterized in that the wire is composed of the copper alloy.

3. A copper or copper alloy wire according to claim 2, characterized in that the copper content in the copper alloy is in the range of 70.0 to 99.9% by mass.

4. A method for manufacturing a copper or copper alloy wire, comprising the steps of: preparing a wire made of copper or a copper alloy; and twisting the wire using a die to obtain a copper or copper alloy wire, wherein, in the diffraction chart of the X-ray diffraction obtained when X-rays are irradiated from a direction perpendicular to the longitudinal direction of the wire, the peak intensity of the copper (111) plane is 50% or more of the sum of the peak intensities of the copper (111) plane and the copper (220) plane.

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