Cu-ag alloy wire and method for producing same

Abstract

The purpose of the present invention is to provide a Cu-Ag alloy wire that can be produced without causing disconnection and that has hardness, specific resistance, and linearity. The Cu-Ag alloy wire solving the above problem comprises: an alloy wire material containing 0.1%-30% by mass of Ag, with the balance being Cu and inevitable impurities; and a first plating layer covering the alloy wire material and including Ni and / or Pd. The alloy wire material has a Vickers hardness of 300 HV or more, a specific resistance of 3.0 μΩ·cm or less, and a radius of curvature of 300 mm or more. In a cross-section perpendicular to the longitudinal direction of the Cu-Ag alloy wire, the ratio of the area of the first plating layer to the total area of the cross-section is less than 1.1%.

Description

Cu-Ag alloy wire and its manufacturing method

[0001] The present invention relates to a Cu—Ag alloy wire and a method for producing the same.

[0002] When testing the electrical characteristics of a test object such as a semiconductor integrated circuit, a probe card with an array of multiple probe pins is generally used, and the tips of the probe pins are brought into contact with the test target location on the test object to test the electrical characteristics. Here, the probe pins are used by repeatedly contacting the test target location thousands or tens of thousands of times. Therefore, the probe pins are required to have sufficient "hardness." Furthermore, the probe pins are also required to have high linearity to prevent contact between adjacent probe pins. Such probe pins are often made of Cu alloy wire, and for example, Patent Document 1 discloses a Cu alloy wire applicable to probe pins.

[0003] Cu alloy wire for probe pins is generally manufactured by straightening the alloy wire to improve its rigidity and linearity. The Cu alloy wire is then processed into a pin shape. However, if the Cu alloy wire is used as is after being processed into a pin shape, the pin may discolor or an oxide film may form on its surface, which may peel off and contaminate the semiconductor. Therefore, it is common to further plate the Cu alloy wire after being processed into a pin shape with Ni and Au, and then use it as a probe pin.

[0004] Japanese Patent Application Laid-Open No. 2019-26921

[0005] However, when plating a Cu alloy wire after processing it into a pin shape, the plating process must be performed in a batch process. This increases costs and makes it difficult to perform the process efficiently. Furthermore, it is difficult to control the thickness of the plating layer formed on the surface of the Cu alloy wire, and the quality is likely to be unstable. Furthermore, batch plating tends to result in a thick plating layer. Therefore, it is believed that plating before processing the Cu alloy wire into a pin shape, particularly before straightening the alloy wire, is efficient and can form a stable, thin plating layer. The inventors of the present invention have extensively studied this method and found that straightening a plated alloy wire is prone to wire breakage during the process. The reason for this is unclear, but it is thought to be as follows: After plating, wiredrawing is performed to a predetermined size. However, if the area ratio of the plating layer to the total cross-sectional area of ​​the wire is large, cracks may occur in the plating layer during wiredrawing. Furthermore, wiredrawing is performed while applying a lubricant, and if the lubricant penetrates and remains in the cracks, the copper alloy substrate will corrode. In the next straightening process, a strong twist is applied to the wire in a direction perpendicular to its longitudinal direction, and the amount of change due to this twist increases the further away from the center of the wire, so the stress on the plating layer is very large. If such stress is applied to a wire with a large area ratio of the plating layer and cracks that occurred during wire drawing, it is thought that breakage will occur starting from the corroded area.

[0006] Therefore, a main object of the present invention is to provide a Cu—Ag alloy wire that can be manufactured without causing breakage and that has hardness, resistivity, and linearity, and a manufacturing method thereof.

[0007] In order to solve the above-mentioned problems, one aspect of the present invention provides a Cu-Ag alloy wire comprising: an alloy wire containing 0.1 to 30 mass% of Ag, with the balance being Cu and unavoidable impurities; and a first plating layer covering the alloy wire and containing at least one of Ni, Pd, and Ag, wherein the alloy wire has a Vickers hardness of 300 HV or more, a resistivity of 3.0 μΩ cm or less, and a radius of curvature of 300 mm or more, and in a cross section perpendicular to the longitudinal direction of the Cu-Ag alloy wire, a ratio of an area of ​​the first plating layer to a total area of ​​the cross section is less than 1.1%.

[0008] According to another aspect of the present invention, there is provided a method for manufacturing a Cu-Ag alloy wire, the method comprising the steps of: preparing an alloy wire containing 0.1 to 30 mass% Ag and the remainder being Cu and unavoidable impurities; plating a surface of the alloy wire with at least one of Ni, Pd, and Ag; and straightening the alloy wire after plating.

[0009] According to the present invention, there are provided a Cu—Ag alloy wire that can be manufactured without causing breakage and that has hardness, resistivity, and linearity, and a method for manufacturing the same.

[0010] 1 is a schematic cross-sectional view of a Cu—Ag alloy wire according to one embodiment of the present invention; 2 is a flowchart showing a method for manufacturing a Cu—Ag alloy wire according to one embodiment of the present invention; 3 is a diagram showing a schematic straightening method in a straightening step; 4 is a diagram showing a schematic straightening method in a straightening step; 5 is a diagram showing a schematic straightening method in a straightening step;

[0011] A Cu—Ag alloy wire according to one embodiment of the present invention and a method for manufacturing the same will be described below. However, the Cu—Ag alloy wire and the method for manufacturing the same of the present invention are not limited to the following embodiment. In this specification, the term "to" indicating a range of values ​​includes both the upper and lower limits of the range.

[0012] [Cu—Ag alloy wire] The Cu—Ag alloy wire of this embodiment can be used, for example, as a conductor for electrical characteristic testing. The Cu—Ag alloy wire is particularly suitable for probe pins used when testing the electrical characteristics of test objects such as semiconductor integrated circuits. However, the uses of the Cu—Ag alloy wire are not limited to this. The Cu—Ag alloy wire can also be used for wiring electronic components, and can be used for any purpose including electrical connection.

[0013] A schematic diagram of a cross section perpendicular to the longitudinal direction of a Cu—Ag alloy wire is shown in Figure 1. As shown in Figure 1, a Cu—Ag alloy wire 10 has an alloy wire 12, a first plating layer 14 covering the alloy wire 12, and a second plating layer 16 covering the first plating layer.

[0014] The alloy wire 12 contains 0.1 to 30 mass%, preferably 10 to 15 mass%, of Ag, with the remainder consisting of Cu and inevitable impurities. The structure of the alloy wire 12 is not particularly limited, but it is preferable from the viewpoint of Vickers hardness, resistivity, and the like that the alloy wire 12 has a structure in which the Cu-based solid solution phase, the Cu-Ag eutectic phase, and the Ag precipitate phase are stretched into a fibrous form by cold working. The Vickers hardness of the alloy wire 12 measured in accordance with JIS Z 2244 may be 300 HV or more, preferably 300 HV to 450 HV. Furthermore, the resistivity of the alloy wire 12 measured and calculated by the double bridge method may be 3.0 μΩ·cm or less, preferably 2.0 μΩ·cm to 3.0 μΩ·cm. Furthermore, the radius of curvature may be 300 mm or more, more preferably 1,000 mm or more. When the Vickers hardness of the alloy wire 12 is 300 HV or higher, wear is unlikely to occur when the Cu—Ag alloy wire 10 is used as a probe. Furthermore, when the resistivity of the alloy wire 12 is 3.0 μΩ·cm or less, accurate testing can be performed. Furthermore, when the radius of curvature is 300 mm or more, contact or entanglement between adjacent probe pins can be prevented when the Cu—Ag alloy wire 10 is used as a probe pin of an electrical characteristic testing device, for example. The above-mentioned radius of curvature was calculated using a Keyence VHX-6000 digital microscope, where three points were arbitrarily selected from the arc of the sample. Here, the diameter of the alloy wire 12 is preferably 10 μm or more and 100 μm or less, and more preferably 10 μm or more and 80 μm or less. When the diameter of the alloy wire 12 is within this range, the diameter of the Cu—Ag alloy 10 is likely to fall within the desired range, making the Cu—Ag alloy 10 easy to use as a conductor for electrical characteristic testing. The properties of the alloy wire 12 are basically maintained even after the first plating layer 14 and the second plating layer 16 are formed.

[0015] On the other hand, the first plating layer 14 may be a layer formed by plating and containing Ni and / or Pd and / or Ag. The first plating layer 14 may contain only one of Ni, Pd, and Ag, or may contain two or more of them. Furthermore, the first plating layer 14 may contain metals other than Ni and Pd. For example, the first plating layer 14 may be composed of an alloy of Ni and various metals, or an alloy of Pd and various metals. However, the total amount of Ni and Pd in ​​the first plating layer 14 relative to the total amount of metals constituting the first plating layer 14 is preferably 90 mass% or more, more preferably 95 mass% or more. It is particularly preferable that the first plating layer 14 be a layer primarily containing Ni. The thickness of the first plating layer 14 is appropriately selected depending on the diameter of the Cu—Ag alloy wire 10. Specifically, the thickness of the first plating layer 14 is adjusted so that, in a cross section perpendicular to the longitudinal direction of the alloy wire 12 Cu—Ag alloy wire 10, the ratio of the area of ​​the first plating layer 14 to the total area of ​​the cross section (the area of ​​the entire Cu—Ag alloy 10) is 1.0% or less. This area ratio is preferably 0.1% or more and less than 1.1%, and more preferably 0.1% or more and 1.0% or less. Plating layers containing Ni or Pd are relatively hard. Therefore, if the first plating layer 14 is thick, cracks are likely to occur during the manufacturing of the Cu—Ag alloy wire 10 (e.g., during the wiredrawing process described below). In contrast, if the ratio of the first plating layer 14 is 1.0% or less, cracks are less likely to occur in the first plating layer 14 during manufacturing. Therefore, a high-quality Cu—Ag alloy wire 10 can be obtained, with no cracks in the first plating layer 14. The area ratio of the first plating layer 14 in the cross section may be measured by observing a cross section perpendicular to the longitudinal direction of the Cu—Ag alloy wire 10 using a microscope or the like. Alternatively, it may be calculated from the diameter of the alloy wire 12 and the thickness of the first plating layer 14. Alternatively, the plating thickness may be calculated from the weight per unit length of the wire before plating, the weight per unit length of the wire after plating, and the specific gravity of the plating material. The specific thickness of the first plating layer 14 is not particularly limited as long as it satisfies the above ratio, but is typically 10 nm or more and 2000 nm or less. The thickness of the first plating layer 14 can be determined by measuring the plating thickness by observing a cross section perpendicular to the longitudinal direction.

[0016] On the other hand, the second plating layer 16 may be any layer containing a metal and formed by plating, and is preferably a layer made of Au or an alloy thereof. However, the second plating layer 16 is not essential to the Cu—Ag alloy wire 10 of this embodiment. For example, if the first plating layer 14 is a layer containing mainly Pd or Ag, the second plating layer 16 may be omitted. On the other hand, if the first plating layer 14 is a layer containing mainly Ni, the second plating layer 16 is preferably included. The thickness of the second plating layer 16 is also appropriately selected depending on the diameter of the Cu—Ag alloy wire 10. Specifically, the thickness of the second plating layer 16 is preferably adjusted so that the ratio of the area of ​​the second plating layer 16 to the total area of ​​the cross section (total area of ​​the Cu—Ag alloy 10) in a cross section perpendicular to the longitudinal direction of the Cu—Ag alloy wire 10 is 10% or less. The area ratio is more preferably 0.1% or more and 10% or less, and even more preferably 0.1% or more and 9.8% or less. In this embodiment, the second plating layer 16 is composed of Au or an alloy thereof, and therefore has a relatively low hardness. Therefore, even if a large load is applied to the second plating layer 16 during wire drawing, cracks are unlikely to occur. Therefore, the thickness of the second plating layer 16 can be made thicker than the thickness of the first plating layer 14. The method for determining the area proportion of the second plating layer 16 in the cross section is the same as the method for determining the area proportion of the first plating layer 14. The specific thickness of the second plating layer 16 is not particularly limited as long as the above proportion can be satisfied, but is typically 10 nm or more and 3000 nm or less. The thickness of the second plating layer 16 can be determined by measuring the plating thickness by observing a cross section perpendicular to the longitudinal direction.

[0017] Here, the electrical conductivity of the Cu—Ag alloy wire 10 is preferably 57% IACS or more. If the electrical conductivity of the Cu—Ag alloy wire 10 is 60% IACS or more, the Cu—Ag alloy wire 10 can be easily used for the various applications described above. There is no particular upper limit to the electrical conductivity of the Cu—Ag alloy wire 10, but the upper limit for a typical Cu—Ag alloy wire 10 is about 85% IACS.

[0018] The elongation of the Cu—Ag alloy wire 10 is preferably 1 to 5%. The elongation can be determined using a precision universal testing machine (for example, manufactured by Shimadzu Corporation). If the elongation of the Cu—Ag alloy wire 10 is 5% or less, for example, when the Cu—Ag alloy wire 10 is used as a probe pin, the end of the probe pin is less likely to sag even if it repeatedly comes into contact with other members.

[0019] Furthermore, the diameter of the Cu—Ag alloy wire 10 is preferably 10 μm or more and 100 μm or less, more preferably 30 μm or more and 70 μm or less, and even more preferably 30 μm or more and 50 μm or less. When the diameter of the Cu—Ag alloy wire 10 is within this range, the Cu—Ag alloy wire 10 can be easily used for various applications, and can particularly be easily used as a conductor for electrical property testing.

[0020] [Method for Manufacturing Cu—Ag Alloy Wire] The above-mentioned Cu—Ag alloy wire can be manufactured by, for example, the following method. However, the manufacturing method of the Cu—Ag alloy wire is not limited to this method. A flowchart of the manufacturing method of this embodiment is shown in Figure 2. This manufacturing method includes a step S1 of preparing an alloy wire containing 0.1 to 30 mass% Ag, with the remainder being Cu and unavoidable impurities (hereinafter also simply referred to as the "preparation step"), a step S2 of plating the surface of the alloy wire with at least one of Ni and Pd (hereinafter also simply referred to as the "first plating step"), a step S3 of further plating with Au (hereinafter also simply referred to as the "second plating step"), a step S4 of drawing the plated alloy wire (hereinafter also simply referred to as the "wiredrawing step"), and a step S5 of straightening the drawn alloy wire (hereinafter also simply referred to as the "straightening step"). As described above, when the first plating layer is Pd or Ag, the second plating layer containing Au may not be necessary, and therefore, in this case, the second plating step S3 may be omitted.

[0021] In the preparation step S1, an alloy wire containing 0.1 to 30 mass% Ag and the remainder consisting of Cu and inevitable impurities is prepared. A more preferred composition of the alloy wire is the same as that of the alloy wire contained in the Cu-Ag alloy wire described above. The alloy wire can be manufactured by any method. For example, the alloy wire may be obtained by drawing a wire manufactured with any casting diameter. The diameter of the prepared alloy wire is usually preferably 1.0 mm or less, more preferably 0.1 mm to 0.6 mm.

[0022] In the first plating step S2, the surface of the alloy wire is plated with at least one of Ni, Pd, and Ag. The plating method used in the first plating step S2 is not particularly limited as long as it can form a plating layer (first plating layer) containing Ni and / or Pd and / or Ag such that the area ratio of the first plating layer to the total area of ​​the cross section of the desired Cu—Ag alloy wire is less than 1.1%, preferably 1.0% or less. However, a method that allows continuous plating of the alloy wire is preferred. Furthermore, the thickness of the resulting plating layer can be adjusted by, for example, the moving speed of the alloy wire during plating. Examples of plating methods include wet plating methods such as electroplating using a known Watts bath, sulfamic acid bath, or citric acid bath, and known electroless plating methods, as well as dry plating methods using sputtering or vapor deposition.

[0023] In the second plating step S3, Au is plated onto the first plating layer. The plating method in the second plating step S3 is not particularly limited as long as it can form an Au-containing plating layer (second plating layer) with the above-mentioned area ratio, i.e., the ratio of the area of ​​the second plating layer to the total area of ​​the cross section of the desired Cu—Ag alloy wire is 10% or less, preferably 9.8% or less. However, a method that allows continuous plating of the alloy wire is preferred. The thickness of the resulting plating layer can be adjusted by, for example, the moving speed of the alloy wire during plating. In the second plating step S3, as in the first plating step S2, the plating layer may be formed by either a wet plating method or a dry plating method.

[0024] In the wiredrawing process S4, the plated alloy wire is drawn to the required wire diameter. In the straightening process S5, the drawn alloy wire is straightened. The straightening process method is not particularly limited as long as it can process the alloy wire so that it satisfies the above-mentioned Vickers hardness, resistivity, and radius of curvature. An example of the straightening process is shown in FIG. 3 . In this method, a master bobbin 100 (supply bobbin) is prepared, on which an alloy wire 10a that has been subjected to the second plating process S3 (or the first plating process S2 if the second plating process S3 is not performed) is wound. Then, while rotating the bobbin 100 forward, the alloy wire 10a is moved in a predetermined direction, and the alloy wire 10a is wound onto a recovery bobbin 200 (first process). Then, in the second process, while rotating the recovery bobbin 200 backward, the previously wound alloy wire 10b is moved in a predetermined direction and wound onto another recovery bobbin 300. This allows the plated alloy wire 10a to be straightened without heat treatment, thereby increasing the radius of curvature and increasing the Vickers hardness, thereby obtaining the Cu—Ag alloy wire 10 described above.

[0025] Another example of straightening is shown in Figures 4 and 5. In this method, the alloy wire 10a that has been subjected to the second plating step S3 (or the first plating step S2 if the second plating step S3 is not performed) is twisted using a processing device 600 shown in Figure 4. In this method, the alloy wire 10a is first supported by a first support portion 612a, a second support portion 612b, and a third support portion 612c of the processing device 600. At this time, the heights and positions of the first support portion 612a, the second support portion 612b, and the third support portion 612c are adjusted so that the angle (α and β in Figure 4) between the alloy wire 10a pressed by the second support portion 612b and the conveying direction is 10 to 70 degrees. Next, while the alloy wire 10a is transported at a predetermined speed from one bobbin 400 side to the other bobbin 500 side, the rotating plates (first rotating plate 611a, second rotating plate 611b) of the processing device 600 are rotated at a predetermined speed in the circumferential direction of the alloy wire 10a, and the alloy wire 10a is wound around the bobbin 500. Next, as shown in FIG. 5 , the alloy wire 10b wound around the bobbin 500 is moved in a predetermined direction, while the (supply) bobbin 500 is rotated in a direction opposite to the direction in which the alloy wire 10b was twisted by the processing device. Then, the alloy wire 10b is wound around the recovery bobbin 700, and the alloy wire 10b is untwisted. This allows the plated alloy wire 10a to be straightened without heat treatment, thereby increasing the radius of curvature and increasing the Vickers hardness. In other words, the above-mentioned Cu—Ag alloy wire 10 is obtained. Although there is a method of improving the radius of curvature by applying heat to the wire (tension annealing), in this case, the alloy wire softens due to the heat and cannot meet the Vickers hardness requirement. Furthermore, the heat generated during tension annealing may cause metal atoms contained in the plating layer and the alloy wire to diffuse into each other, forming a new alloy layer between the plating layer and the alloy wire. In this case, the alloy layer may increase resistivity or reduce the inherent properties of the plating (such as oxidation resistance). Therefore, cold straightening without applying heat is recommended. In the manufacturing method of this embodiment, the thickness of the plating layer (first plating layer) containing Ni, Pd, or Ag formed in the first plating step S2 described above is made sufficiently thin.Therefore, in the wire drawing process S4, cracks are unlikely to occur in the plating layer (particularly the first plating layer), and a high-quality Cu—Ag alloy wire that does not break during straightening is produced.

[0026] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited by these examples, and modifications of the embodiments are possible without departing from the spirit of the present invention.

[0027] (1) Preparation of Cu—Ag Alloy Wire [Example 1] A plurality of alloy wires containing 10% by mass of silver, with the remainder being copper and unavoidable impurities, and having a diameter of 0.6 mm were prepared (preparation step). Subsequently, a 0.8 μm thick Ni plating layer was formed on the surface of the alloy wire by electroplating. Then, a 2.6 μm thick Au plating layer was further formed on the Ni plating layer by electroplating. The thickness of each plating layer was determined by measuring the plating thickness by observing a cross section perpendicular to the longitudinal direction. After plating layer formation, the ratio of the area of ​​the Ni plating layer to the total area of ​​the wire was 0.5% and the ratio of the area of ​​the Au plating layer to the total area was 1.7%, as confirmed by measuring the plating thickness by observing a cross section perpendicular to the longitudinal direction.

[0028] Thereafter, the plated alloy wire was subjected to wire drawing to reduce the diameter from 0.6 mm to 0.05 mm.

[0029] Then, using the processing device 600 shown in FIG. 4, the alloy wire 10a after the Ni plating layer and the Au plating layer were moved at a constant speed, while the alloy wire 10a was pressed 4.0 mm perpendicular to the longitudinal direction and rotated at a speed of 6000 rpm in the circumferential direction of the alloy wire 10a. That is, the angles α and β between the alloy wire 10a pressed by the second support portion 612b and the conveying direction of the alloy wire 10a were set to 30°, and the twisting amount was adjusted to 1 to 15 turns / mm. Then, as shown in FIG. 5, the alloy wire 10b was untwisted and wound on a bobbin. The untwisting amount was adjusted to about 0.7% of the twisting amount (0.01 to 0.11 turns / mm), and a Cu—Ag alloy wire was obtained.

[0030] Comparative Examples 1 and 2 The alloy wire was subjected to the straightening process in the same manner as in Example 1, without forming the Ni plating layer and the Au plating layer.

[0031] [Examples 2 to 4 and Comparative Example 3] Cu—Ag alloy wires were obtained in the same manner as in Example 1, except that the thicknesses of the Ni plating layer and the Au plating layer were changed as shown in Table 1. The thicknesses of the Ni plating layer and the Au plating layer were adjusted by adjusting the plating speed and current density.

[0032] (2) Evaluation of Samples (2.1) Presence or Absence of Breakage Whether or not breakage occurred in the alloy wire during the straightening process was visually determined.

[0033] (2.2) Presence or absence of oxidation The presence or absence of oxidation of the Cu-Ag alloy wire was evaluated by energy dispersive X-ray analysis (EDX) using a scanning electron microscope (SEM). The oxygen concentration on the sample surface, displayed on the entire screen at 10,000x magnification, was quantitatively measured at an acceleration voltage of 10 kV. When the measured oxygen concentration was 5 mass% or more, it was determined that oxidation had occurred. The results are shown in Table 1.

[0034] (2.3) Measurement of Vickers Hardness The hardness (Vickers hardness) of each sample (Cu-Ag alloy wire) was measured using a Vickers hardness tester in accordance with JIS Z 2244. A Vickers hardness tester (AMT-X7AFS) manufactured by Matsuzawa Co., Ltd. was used as the measuring device. The measurement conditions were as follows: Load: 25 gf (10 gf for φ0.03 mm) Holding time: 15 seconds The measurement results are shown in Table 1.

[0035] (2.4) Measurement of specific resistance For each sample (Cu-Ag alloy wire), the electrical resistance was measured for five samples using the double bridge method in a room controlled at 20°C (±2°C), and the average value of the specific resistance (μΩ cm) was calculated. The distance between the voltage terminals was 500 mm. The calculation results are shown in Table 1.

[0036] (2.5) Evaluation of linearity To evaluate linearity, the radius of curvature of each sample (Cu-Ag alloy wire) was measured. Specifically, using a digital microscope VHX-6000 manufactured by Keyence Corporation, three points were arbitrarily selected from the arc of the sample, and the radius of curvature (mm) was calculated. The calculation results are shown in Table 1.

[0037]

[0038] As shown in Table 1 above, when no plating layer was formed, oxidation occurred in the alloy wire (Comparative Examples 1 and 2). In contrast, by forming a first plating layer containing Ni around the alloy wire, oxidation of the alloy wire could be suppressed (Examples 1 to 4 and Comparative Example 1). However, when the ratio of the area of ​​the first plating layer (Ni plating layer) to the total area of ​​the cross section perpendicular to the longitudinal direction of the Cu—Ag alloy wire exceeded 1%, wire breakage was likely to occur (Comparative Example 1). It is believed that cracks occurred in the first plating layer during straightening processing, and wire breakage occurred from these cracks. In contrast, when the area ratio of the first plating layer (Ni plating layer) was less than 1.1%, wire breakage did not occur in either the case where the diameter of the alloy wire was 0.05 mm or 0.03 mm (Examples 1 to 4). Furthermore, oxidation did not occur in the Cu—Ag alloy wire.

[0039] The present invention provides a Cu—Ag alloy wire that can be manufactured without breakage and has hardness, resistivity, and linearity. The Cu—Ag alloy wire can be used for various applications, such as contact probes and lead wires for electrical characteristic testing devices.

[0040] REFERENCE SIGNS LIST 10 Cu—Ag alloy wire 10a Alloy wire after plating 10b Alloy wire after twisting 12 Alloy wire 14 First plating layer 16 Second plating layer 100, 200, 300, 400, 500, 700 Bobbin 600 Processing device 611a First rotating plate 611b First rotating plate 612a First support portion 612b Second support portion 612c Third support portion

Claims

1. A Cu-Ag alloy wire comprising: an alloy wire containing 0.1 to 30 mass% Ag with the remainder being Cu and unavoidable impurities; and a first plating layer covering the alloy wire and containing at least one of Ni, Pd, and Ag, wherein the Cu-Ag alloy wire has a Vickers hardness of 300 HV or more, a resistivity of 3.0 μΩ·cm or less, and a radius of curvature of 300 mm or more; and in a cross section perpendicular to the longitudinal direction of the Cu-Ag alloy wire, the ratio of an area of ​​the first plating layer to a total area of ​​the cross section is less than 1.1%.

2. The Cu-Ag alloy wire according to claim 1, wherein the first plating layer contains Ni, and the Cu-Ag alloy wire further comprises a second plating layer containing Au on the first plating layer.

3. The Cu-Ag alloy wire according to claim 2, wherein in a cross section perpendicular to the longitudinal direction of said Cu-Ag alloy wire, the ratio of the area of ​​said second plating layer to the total area of ​​said cross section is 9.8% or less.

4. A method for manufacturing a Cu-Ag alloy wire, comprising: a step of preparing an alloy wire containing 0.1 to 30 mass% Ag with the remainder being Cu and unavoidable impurities; a step of plating a surface of the alloy wire with at least one of Ni, Pd, and Ag; and a step of straightening the alloy wire after plating.

5. The method for producing a Cu-Ag alloy wire according to claim 4, wherein the plating step is a step of plating the surface of the alloy wire with Ni, and the method further comprises a step of plating the Ni-plated surface with Au before the straightening step.

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