Copper alloy and electronic components

Abstract

Provided is a copper alloy with improved bend formability. 【Solution means】The copper alloy of the present disclosure contains 0.50 to 3.0% by mass of Co and 0.10 to 1.0% by mass of Si, the balance consisting of Cu and unavoidable impurities, has an elongation at break of 5% or more, and a work hardening coefficient of 0.0175 or more.

Description

Technical Field

[0001] The present invention relates to a copper alloy and an electronic component containing the same.

Background Art

[0002] In recent years, with the miniaturization of electronic devices, the requirements for materials used in electronic components such as lead frames, terminals, and connectors have become more stringent. As materials used for such electronic components, for example, a Cu-Co-Si alloy, which is a precipitation-hardening type copper alloy, may be used because it has high conductivity, strength, and workability (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to effectively ensure the high strength of the Cu-Co-Si-based copper alloy, in the manufacturing process, it is necessary to increase the degree of rolling in the finish rolling process performed after the aging treatment process in which intermetallic compounds such as Co-Si-based compounds are precipitated as fine particles. However, a high degree of working in the finish rolling process may reduce the elongation of the copper alloy. When the elongation of the copper alloy decreases, for example, during bending forming, necking, which is a phenomenon in which the cross-sectional area of the bent portion locally decreases, is likely to occur. When such necking occurs in the copper alloy, it may lead to a decrease in the yield of the electronic component containing the same.

[0005] Therefore, an object of the present disclosure is to provide a copper alloy with improved bend formability and an electronic component containing the same.

Means for Solving the Problems

[0006] The copper alloy of the present disclosure includes the following aspects. [Aspect 1] It contains 0.50 to 3.0% by mass of Co and 0.10 to 1.0% by mass of Si, and the balance is composed of Cu and unavoidable impurities. The elongation at break measured by the following method is 5% or more. A copper alloy having a work hardening coefficient calculated by the following method of 0.0175 or more. Elongation at break: Using a JIS-13B test piece, a tensile test is performed at a tensile speed of 5 mm / min. Work hardening coefficient: A tensile test is performed in accordance with JIS-Z2253 (2011). When the strain 0.005 smaller than the nominal strain (ε) at the maximum stress is defined as the initial strain (ε0), the slope of the logarithmic true stress - logarithmic true strain curve in the range of ε0 to ε is defined as the work hardening coefficient. [Aspect 2] The copper alloy according to Aspect 1, having a 0.2% proof stress of 500 MPa or more. [Aspect 3] The copper alloy according to Aspect 1 or 2, having a conductivity of 30% IACS or more. [Aspect 4] The copper alloy according to any one of Aspects 1 to 3, having a crystal grain size of 10 μm or less. [Aspect 5] The copper alloy according to any one of Aspects 1 to 4, having an elongation at break of 10% or less. [Aspect 6] The copper alloy according to Aspect 5, having an elongation at break of 5.6% or more and 9.6% or less. [Aspect 7] The copper alloy according to any one of Aspects 1 to 6, having a work hardening coefficient of 0.1000 or less. [Aspect 8] The copper alloy according to Aspect 7, having a work hardening coefficient of 0.0639 or less. [Aspect 9] The copper alloy according to any one of Aspects 1 to 8, having a thickness of 0.020 mm or more and 0.400 mm or less. [Aspect 10] A copper alloy according to any one of Aspects 1 to 9, further containing in total 0.005 to 0.80% by mass of at least one element selected from the group consisting of Mg, Fe, P, Mn, Zn, Ni, and Cr. [Aspect 11] A copper alloy according to any one of Aspects 1 to 10, wherein the arithmetic mean roughness Ra is 0.245 μm or less. [Aspect 12] The copper alloy according to Aspect 11, wherein the arithmetic mean roughness Ra is 0.200 μm or more.

[0007] An electronic component of the present disclosure is an electronic component including the copper alloy of the present disclosure described above. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a copper alloy with improved bend formability and an electronic component including the same. [Brief Description of the Drawings]

[0009]

Figure 1

[0010] Hereinafter, a copper alloy according to an embodiment of the present disclosure (hereinafter also referred to as "the present embodiment") will be described, but the present invention is not limited to the following embodiments. In the present disclosure, "A to B" means "A or more and B or less". A and B represent numerical values.

[0011] The copper alloy of the present embodiment contains 0.50 to 3.0% by mass of Co and 0.10 to 1.0% by mass of Si, and the balance is an alloy composed of Cu and unavoidable impurities. Further, the copper alloy of the present embodiment has an elongation at break of 5% or more measured by the following method and a work hardening coefficient calculated by the following method of 0.0175 or more. Elongation at break: Using a JIS-13B test piece, a tensile test is performed at a tensile speed of 5 mm / min. Work hardening coefficient: When a tensile test is performed in accordance with JIS-Z2253 (2011), and the strain that is 0.005 less than the nominal strain (ε) at the maximum stress is defined as the initial strain (ε0), the slope of the logarithmic true stress - logarithmic true strain curve in the range of ε0 to ε is defined as the work hardening coefficient. According to the above configuration, the bend formability of the copper alloy can be improved.

[0012] As described above, in order to ensure the strength of the copper alloy, it is necessary to increase the degree of final rolling, but there is a concern that the elongation will decrease. Due to the decrease in the elongation of the copper alloy, necking, which is a phenomenon in which the cross-sectional area of the bent portion locally decreases during bending, is likely to occur. When such necking occurs in the bent portion of the copper alloy subjected to bending, it may lead to a decrease in the yield of electronic components including the same. Specifically, when insert molding is performed using the copper alloy subjected to bending, a gap may be generated between the copper alloy (especially the bent portion) and the mold. There is a risk that resin leaks from the gap (resin covering), leading to a decrease in yield. As a result of various studies by the inventors in response to such problems, in the Co - Si Corson alloy, by increasing the strength by final rolling and annealing (softening) for the purpose of recovering the elongation after final rolling, it was found that necking during bending can be suppressed and the bend formability can be improved while maintaining high strength.

[0013] The copper alloy of this embodiment can also have high strength and high conductivity. High strength means, for example, that the 0.2% proof stress is 500 MPa or more. High conductivity means, for example, that the conductivity is 67% IACS or more.

[0014] <Composition> The copper alloy of this embodiment contains 0.50 to 3.0 mass% of Co and 0.10 to 1.0 mass% of Si. Co and Si, by performing aging treatment, form fine precipitated particles of an intermetallic compound mainly composed of Co 2 Si, and the strength of the copper alloy is improved. Also, Co 2 With the precipitation of Si, the conductivity of the copper alloy is improved. When the concentration of Co is less than 0.50% by mass or the concentration of Si is less than 0.10% by mass, the desired strength cannot be obtained even if the other component is added sufficiently. Also, when the concentration of Co exceeds 3.0% by mass or the concentration of Si exceeds 1.0% by mass, although sufficient strength can be obtained, the conductivity decreases, and furthermore, coarse Co-Si-based particles that do not contribute to the improvement of strength are generated in the matrix phase, leading to a decrease in bend formability. Therefore, the Co content is set to 0.50 to 3.0% by mass and the Si content is set to 0.10 to 1.0% by mass.

[0015] In this embodiment, the concentration of Co is preferably 1.0 to 2.5% by mass, more preferably 1.8 to 2.0% by mass. Also, the concentration of Si is preferably 0.20 to 0.80% by mass, more preferably 0.38 to 0.47% by mass.

[0016] The copper alloy of this embodiment can further contain, as elements other than the above elements, at least one element selected from the group consisting of Mg, Fe, P, Mn, Zn, Ni, and Cr (hereinafter also referred to as "additive element") in a total amount of 0.005 to 0.80% by mass. Thereby, strength, heat resistance, stress relaxation resistance, etc. can be improved. The total concentration of the additive elements can be 0.005 to 0.15% by mass. If the total amount of the additive elements is 0.005% by mass or more, the above effects are likely to occur. If the total amount of the additive elements is 0.80% by mass or less, there is a tendency to obtain the above effects without degrading conductivity and bend formability.

[0017] The copper alloy of this embodiment may contain, in total, 0.20% by mass or less, or may contain 0.10% by mass or less of at least one element selected from the group consisting of Mg, Fe, P, Mn, Zn, Ni, and Cr.

[0018] The balance of the copper alloy of this embodiment (i.e., other than the elements described above) consists of Cu and inevitable impurities. An unavoidable impurity means an impurity element that cannot be avoided from being mixed into the material during the manufacturing process, and examples thereof include S and O. The content of each element included as an unavoidable impurity is not particularly limited, but for example, it is 0.001% by mass or less.

[0019] The composition of the copper alloy can be confirmed by ICP emission spectrometry (internal standard method). As the ICP emission spectrometer (ICP-OES, inductively coupled plasma optical emission spectrometer), measurement is performed using SPS3100 manufactured by Hitachi High-Tech Sciences Corporation or an equivalent device. In the case of ICP emission spectrometry (internal standard method), a sample of the copper alloy dissolved in a mixed acid containing hydrochloric acid and nitric acid (hydrochloric acid, nitric acid, and water in a volume ratio of 2:1:2) is diluted and used. As the internal standard element, Y (yttrium) is used.

[0020] <Elongation at break> The copper alloy of the present embodiment has an elongation at break of 5% or more measured by the following method. When the elongation at break is 5% or more, the occurrence of necking and bending wrinkles during bending forming can be reduced or suppressed. The elongation at break is preferably 5.6% or more. The upper limit of the elongation at break is not particularly limited, but for example, it can be 10% or less, and can also be 9.6% or less. The elongation at break is calculated by performing a tensile test at a tensile speed of 5 mm / min using a JIS-13B test piece. More specifically, the elongation at break is calculated by performing a tensile test under the following conditions in accordance with JIS-Z2241 with the above test piece such that the tensile direction is perpendicular to the rolling direction. The conditions for the tensile test are: test piece width: 12.7 mm, room temperature: 15 to 35 °C, tensile speed: 5 mm / min, gauge length: 50 mm.

[0021] <0.2% proof stress> The 0.2% proof stress of the copper alloy of the present embodiment may be 500 MPa or more, preferably 550 MPa or more. When the 0.2% proof stress is 500 MPa or more, parts obtained from the copper alloy can be more suitably used for various applications, for example, for electronic parts. In particular, when the copper alloy is used for the plug of a connector as an electronic part (for example, a portion that slides against other electronic parts), it is possible to prevent shaving when fitting with other parts. The upper limit of the 0.2% proof stress of the copper alloy of the present embodiment is not particularly limited, but the 0.2% proof stress may be, for example, 800 MPa or less, or 700 MPa or less. The 0.2% proof stress is calculated by performing a tensile test in accordance with JIS-Z2241 using a JIS-13B test piece with the tensile direction perpendicular to the rolling direction. The conditions of the tensile test are the same as those of the tensile test at the above-mentioned elongation at break.

[0022] <Conductivity> The conductivity of the copper alloy of the present embodiment may be 30% IACS or more. The conductivity of the copper alloy of the present embodiment may be 50% IACS or more, preferably 67% IACS or more, and more preferably 69% IACS or more. When the conductivity is 30% IACS or more, it can be used more effectively for electronic parts. The upper limit of the conductivity of the copper alloy of the present embodiment is not particularly limited, but the conductivity may be, for example, 90% IACS or less, or 80% IACS or less. The conductivity can be measured by the four-terminal method in accordance with JIS-H0505. A double bridge is used for the measurement, and the resistance can be measured based on the average cross-sectional area method. The conductivity can be measured at room temperature (25 °C) in the direction parallel to the rolling direction. The gauge distance (distance between electrical resistance measurements) is 50 mm.

[0023] <Crystal grain size> The copper alloy of the present embodiment can be manufactured through a solution treatment as described later, but the crystal grain size after the final solution treatment is preferably 10 μm or less. When the crystal grain size is 10 μm or less, the dimensional error during press working can be suppressed. More preferably, the crystal grain size is 8.0 μm or less. Also, the crystal grain size may be 2.0 μm or more. The crystal grain size is measured by the following method. First, after mirror-polishing the rolling parallel cross-section of the copper alloy plate, a metal structure is revealed using a solution composed of ferric chloride (10 g), hydrochloric acid (3 mL, concentration: 35 - 37%), and distilled water (120 mL). Next, it is calculated by the cutting method in accordance with JIS-H0501.

[0024] <Work hardening coefficient (n value)> In the copper alloy of the present embodiment, the work hardening coefficient (hereinafter, also referred to as "n value") calculated by the following method is 0.0175 or more. When the n value is 0.0175 or more, the workability (mainly the flanging formability) is good, and the bending formability is improved. Preferably, the n value is 0.0340 or more. Also, the n value may be 0.1000 or less, or may be 0.0639 or less.

[0025] 〔Measurement method〕 A tensile test is conducted in accordance with JIS-Z2253 (2011). When the strain 0.005 smaller than the nominal strain (ε) at the maximum stress is defined as the initial strain (ε0), the slope of the logarithmic true stress - logarithmic true strain curve in the range of ε0 to ε is defined as the work hardening coefficient. More specifically, for the tensile test, a JIS-13B test piece is obtained using a copper alloy plate having a thickness of 0.03 mm to 0.1 mm, and the test is conducted in accordance with JIS-Z2241 such that the tensile direction is perpendicular to the rolling direction. The difference between the length L between the gauge points when the test piece breaks and the gauge distance L0 before the test is obtained as a percentage. The conditions for the tensile test for calculating the n value are the same as the measurement conditions for the elongation at break described above. The n value is calculated in the region from when the straight line starts to curve to when necking occurs in the stress - strain curve. On the other hand, the elongation at break is calculated including the region from when necking occurs to when fracture occurs.

[0026] <Arithmetic mean roughness Ra> The copper alloy of this embodiment may have an arithmetic mean roughness Ra (hereinafter, also referred to as "Ra") measured by the following method of 0.245 μm or less. When the Ra measured by the following measurement method is 0.245 μm or less, parts obtained from the copper alloy can be more preferably used for various applications, for example, for electronic parts. Further, Ra may be 0.220 μm or less. Ra may be 0.200 μm or more. The lower limit of Ra is not limited. For example, Ra may be 0.200 μm or more.

[0027] 〔Measurement method〕 With the inner radius r being 0 mm and the sample width being 10 mm, a W-bending test is performed in accordance with JBMA T307:1999. As the testing machine, an AutoCom C-type universal testing machine (AC-100KN-C) is used. The bending direction is perpendicular to the rolling direction. The test load is 50 kN and the test speed is 5 m / min. As the mold, a CES M0002-B type is used. Ra is measured on the surface of the bent portion of the sample with a laser microscope (Keyence, VK-X) or a device equivalent thereto. The observation magnification is 500 times, the measurement location is the center of the plate width, the correction is to approximate the horizontal plane by quadratic surface correction after setting the reference plane to the bending apex, and the measurement range is ±60 μm in the long side direction from the bending apex. Ra is measured with a plurality of line roughnesses (number of lines: 10, interval: 15 μm) in accordance with JIS-B0601:2001. The measurement ambient temperature is 20 to 25°C. The main setting conditions in the laser microscope and analysis software are as follows.

[0028] 〔Measurement settings〕 Measurement mode: Basic setting Scan mode: Laser confocal Measurement size: Standard (1024×768) Measurement quality: High precision Measurement pitch: 0.13 μm RPD: ON Brightness 1: About 6500 - 7500 (varies with fine focus adjustment) Brightness 2: Automatic (9500) Illumination Filter 1: Approximately 10 - 30% (varies with fine focus adjustment) Illumination Filter 2: Automatic (approximately 10 - 30% (varies with fine focus adjustment)) Double Scan: OFF Average Number of Times: 1 time Do Not Acquire Color Image: OFF Fine Mode: ON Enable Processing of Noise Region: OFF 〔Illumination〕 Coaxial Incidence: 100 Ring Illumination: OFF 〔Z - axis〕 Z - axis Mode: Recommended Setting Measurement Upper Limit: Approximately 9900 - 10100 μm (varies with fine focus adjustment) Measurement Lower Limit: Approximately 10000 - 10100 μm (varies with fine focus adjustment) Z - measurement Distance Fixed: ON Z - measurement Distance: Approximately 20 μm (varies with fine focus adjustment) Automatic Upper and Lower Limits · Automatic Brightness: OFF 〔Head〕 Head: R Objective Lens Name: Plan (CF IC EPI Plan 50X) Objective Lens Magnification: 50X Lens NA: 0.800 WD: 0.54 mm Field Curvature Correction: ON Light Quantity Eccentricity Correction: ON Ring Illumination Correction: ON XY Calibration: 268.846 nm / pixel Z Calibration: 1.000 (0.100 nm / digit) 〔Camera Settings〕 Brightness Mode: Auto Brightness (Auto): Approximately 27 (varies with fine focus adjustment) Brightness (Manual): 1 Edge Enhancement: 5 〔Laser Settings〕 γ Coefficient (γ Correction Value): 0.45 γ Offset: 0% Black and White Inversion: OFF Edge Enhancement Type: None Edge Enhancement Direction: Vertical Edge Enhancement Strength: Weak 〔Other condition settings shown on the worksheet〕 Measurement Mode: Surface Shape Optical Zoom Magnification: 1.0x Filter: OFF Camera Gain: 0 dB Shutter Speed: Auto White Balance Mode: Manual White Balance R: 0 White Balance B: 0 Received Light Quantity Correction Mode: γ Correction Head Type: VK-X105 Vividness: 5 Contrast: 5 Brightness: 0 AI Noise Reduction: OFF Slope Noise Filter: OFF 〔Analysis Conditions〕 Image Processing: Surface Shape Correction Performed (Cutoff Wavelength 0.08 mm) Surface Roughness Setting (Filter Setting) Filter Type: Gaussian S-Filter (Low Pass Filter): None F-Operation (Shape Correction): None L-Filter (High Pass Filter): None Correction of End Effect: ON

[0029] <Shape> The shape of the copper alloy of this embodiment is not particularly limited as long as it is an object having a three-dimensional shape with a certain thickness, and it may be plate-shaped. That is, the copper alloy of this embodiment may be a copper alloy plate.

[0030] In the present disclosure, the "plate" means a shape having a certain thickness and a substantially rectangular cross-section, and may also have a shape with a curved surface. Further, the "plate" may be a flat shape having a substantially uniform thickness and a substantially rectangular cross-section. A plate having a thin thickness (for example, less than 0.1 mm) may also be referred to as "foil".

[0031] The thickness of the copper alloy of the present embodiment is, for example, 0.020 mm or more and 0.400 mm or less. The lower limit of the thickness of the copper alloy may be, for example, 0.030 mm or more, or may be 0.059 mm or more. The upper limit of the thickness of the copper alloy may be, for example, 0.100 mm or less, or may be 0.079 mm or less.

[0032] In the present disclosure, the "thickness of the plate" may also be referred to as "plate thickness". The plate thickness of the copper alloy is measured using a micrometer in accordance with JIS-B7502. As the micrometer, BMS-25MX manufactured by Mitutoyo Corporation or a device equivalent thereto is used.

[0033] <Manufacturing method of copper alloy> The copper alloy of the present embodiment can be manufactured by the following method. The copper alloy of the present embodiment is usually hot-rolled from an ingot, and then annealing and rolling are repeated on the obtained intermediate to adjust it to a desired plate thickness. Next, solution treatment, aging treatment, finish rolling, and stress relief annealing are performed on the intermediate with the adjusted plate thickness in this order. Thus, the copper alloy of the present embodiment can be manufactured.

[0034] During each of the above steps, grinding, polishing, shot blasting, pickling, etc. for removing the oxide scale on the surface of the intermediate can be appropriately performed. Further, annealing may be added as necessary during each of the above steps.

[0035] In the solution treatment, silicides such as Co-Si compounds are dissolved in the Cu matrix of the intermediate, and at the same time, the Cu matrix is recrystallized. The solution treatment may be performed under general conditions. The conditions of the solution treatment are not particularly limited, but for example, the material temperature is 900 °C or higher and 1 second to 10 minutes.

[0036] In the aging treatment, the silicide solid-dissolved in the Cu matrix of the intermediate during the solution treatment is precipitated as fine particles of an intermetallic compound mainly composed of Co 2 Si. As a result, the strength and conductivity increase. The conditions for the aging treatment are not particularly limited, but for example, they are 375 to 625 °C and 0.5 to 50 hours, and can also be 400 to 550 °C.

[0037] The finish rolling is a process of generating Orowan loops around the fine particles precipitated in the Cu matrix of the intermediate to increase the strength. The rolling reduction (%) is the thickness of the intermediate before rolling as T 0、 The thickness of the intermediate after rolling as T 1 When doing so, (T 0 - T 1 ) / T 0 × 100. The rolling reduction of the finish rolling is, for example, 10 to 50%. When the rolling reduction of the finish rolling is lowered, a decrease in the n value can be suppressed. When the rolling reduction of the finish rolling is increased, the 0.2% proof stress can be improved. Also, when the rolling reduction of the finish rolling is increased, the conductivity tends to decrease. The rolling reduction can also be 10 to 40%.

[0038] The stress relief annealing can be carried out continuously, for example, by passing a copper strip as an intermediate through a furnace at a line speed of 10 m / min or more. The temperature of the stress relief annealing is, for example, 400 to 600 °C. The time of the stress relief annealing is, for example, 3 to 30 seconds.

[0039] The conditions for the stress relief annealing need to be adjusted according to the rolling reduction of the finish rolling. For example, when the rolling reduction of the finish rolling is high, it is necessary to adjust by raising the treatment temperature or lengthening the treatment time. When the treatment temperature of the stress relief annealing is raised or the treatment time is lengthened, the n value and the elongation at break can be increased. Also, when either or both of the adjustment of raising the treatment temperature of the stress relief annealing and the adjustment of lengthening the treatment time are carried out, although the conductivity increases, the 0.2% proof stress tends to decrease.

[0040] <Electronic component> The electronic component of the present embodiment contains the copper alloy of the present embodiment. More specifically, the electronic component of the present embodiment has a copper alloy component obtained by processing the copper alloy of the present embodiment inside the electronic component.

[0041] According to the above configuration, since the copper alloy of the present embodiment is excellent in bend formability, in the present embodiment, for example, it is possible to manufacture an electronic component in which the occurrence of constriction or the like is suppressed and the yield is improved. Further, since the copper alloy of the present embodiment can have high strength and high conductivity in addition to excellent bend formability, in the present embodiment, the electronic component can be miniaturized and space saving can be realized. Examples of the electronic component include a terminal and a connector. The terminal is, for example, a power terminal. The connector is, for example, a board-to-board connector. Such electronic components such as terminals and connectors can be manufactured, for example, by a manufacturing method including a step of bending a copper alloy, disposing the copper alloy component in a mold, and performing insert molding with a predetermined resin composition.

[0042] As described above, the embodiments of the present disclosure have been described. However, the copper alloy and the electronic component of the present disclosure are not limited to the above examples, and can be appropriately modified.

Example

[0043] The copper alloys of each example and each comparative example were prepared as follows. In Example 1, electrolytic copper was used as a raw material, and a copper alloy having the composition shown in Table 1 was melted using an air melting furnace and cast into an ingot. Hot rolling was performed on this ingot. After hot rolling, heat treatment and rolling for the purpose of softening the intermediate were repeated, solution treatment, aging treatment, and finish rolling were performed, and then stress relief annealing was performed under the conditions shown in Table 1. In finish rolling, Examples 1 and 2 were finish rolled in the range of 10 to 50%. Here, Example 1 had a higher degree of working than Example 2. In Examples 5 to 7 and Comparative Example 2, the degree of working in finish rolling was the same as that in Example 1. In Examples 3 to 4 and Comparative Example 1, the degree of working in finish rolling was the same as that in Example 2. In addition, the copper alloys of Examples 2 to 7 and Comparative Examples 1 and 2 were produced by the same method as the production method of the copper alloy of Example 1, except for the degree of working in finish rolling and the conditions of strain relief annealing. As described above, copper alloy sheets of Examples and Comparative Examples having the thicknesses shown in Table 1 were obtained.

[0044]

Table 1

[0045] For the obtained copper alloys of Example 1 and Comparative Example 1 and their intermediates, each physical property was measured by the following method. The measurement results are shown in Table 1. <Thickness> The thickness of the copper alloy was measured using a BMS-25MX manufactured by Mitutoyo Corporation.

[0046] <Composition> The composition of the obtained copper alloy was confirmed by ICP emission spectrometry (internal standard method). As the ICP emission spectrometer, an SPS3100 (34HV) manufactured by Hitachi High-Technologies Corporation was used. A sample of the copper alloy dissolved in a mixed acid containing hydrochloric acid and nitric acid (hydrochloric acid, nitric acid, and water in a volume ratio of 2:1:2) was diluted and used as a measurement sample. As the internal standard element, Y (yttrium) was used.

[0047] In the copper alloys of Examples and Comparative Examples, Mg, Fe, P, Mn, Zn, Ni, and Cr were contained in a total amount of 0.15% by mass or less.

[0048] <Elongation at break, 0.2% proof stress> The elongation at break and 0.2% proof stress were calculated by measuring in accordance with JIS-Z2241 using JIS-13B test pieces obtained from each copper alloy sheet with the tensile direction perpendicular to the rolling direction. The conditions of the tensile test were as follows: specimen width: 12.7 mm, room temperature: 15 to 35°C, tensile speed: 5 mm / min, gauge length: 50 mm.

[0049] <Work hardening coefficient (n value)> The n value was obtained by using each copper alloy plate to obtain a JIS-13B test piece, and then a tensile test was conducted in accordance with JIS-Z2241 with the tensile direction perpendicular to the rolling direction. The conditions of the tensile test were as follows: specimen width: 12.7 mm, room temperature: 15 - 35 °C, tensile speed: 5 mm / min, gauge length: 50 mm. The difference between the length L between the marks when the test piece broke and the gauge distance L0 before the test was determined as a percentage.

[0050] When the strain 0.005 smaller than the nominal strain (ε) at the maximum stress was defined as the initial strain (ε0), the slope of the logarithmic true stress - logarithmic true strain curve in the range of ε0 to ε was defined as the work hardening coefficient.

[0051] <Crystal grain size> The crystal grain size was measured by the following method. First, after mirror-polishing the rolling parallel cross-section of each copper alloy plate, the metal structure was revealed using a solution composed of ferric chloride (10 g), hydrochloric acid (3 mL, concentration: 35 - 37%) and distilled water (120 mL). Then, it was calculated by the cutting method in accordance with JIS-H0501. It was measured under the above conditions. The crystal grain sizes in the copper alloys of Examples 1 - 7 and Comparative Examples 1 - 2 were all 5.5 μm.

[0052] <Conductivity> The conductivity was measured by the four-terminal method in accordance with JIS-H0505. A double bridge was used for the measurement, and the resistance measurement was performed based on the average cross-sectional area method. The conductivity was measured at room temperature (25 °C) in the direction parallel to the rolling direction. The gauge distance (distance between electrical resistance measurements) was 50 mm.

[0053] <Arithmetic mean roughness Ra> By measuring the arithmetic mean roughness (hereinafter also referred to as "Ra") after the bending test, it is possible to evaluate the occurrence tendency of bending wrinkles, and thus constriction, as well as the bending formability. Specifically for the Ra measurement, with the inner radius r being 0 mm and the sample width being 10 mm, a W-bending test was conducted in accordance with JBMA T307:1999. As the testing machine, an AutoCom C-type universal testing machine (AC-100KN-C) was used. The bending direction was set to be perpendicular to the rolling direction. The test load was 50 kN and the test speed was 5 m / min. As the mold, a CES M0002-B type was used.

[0054] Ra was measured on the surface of the bent part of the sample using a laser microscope (Keyence, VK-X). The observation magnification was 500 times, the measurement location was the center of the plate width, the correction was to approximate the horizontal plane by quadratic surface correction after setting the reference plane to the bending apex, and the measurement range was ±60 μm in the long side direction from the bending apex. Ra was measured in accordance with JIS-B0601:2001 with multiple line roughness (number of lines: 10, interval: 15 μm). The measurement environmental temperature was set to 20 - 25 °C. The main setting conditions for the laser microscope and analysis software were as follows.

[0055] 〔Measurement settings〕 Measurement mode: Basic settings Scan mode: Laser confocal Measurement size: Standard (1024×768) Measurement quality: High precision Measurement pitch: 0.13 μm RPD: ON Brightness 1: Approximately 6500 - 7500 (varying with fine focus adjustment) Brightness 2: Automatic (9500) Illumination filter 1: Approximately 10 - 30% (varying with fine focus adjustment) Illumination filter 2: Automatic (approximately 10 - 30% (varying with fine focus adjustment)) Double scan: OFF Average number of times: 1 time Do not acquire color image: OFF Fine mode: ON Enable noise area processing: OFF 〔Illumination〕 Coaxial Incidence: 100 Ring Illumination: OFF 〔Z - axis〕 Z - axis Mode: Recommended Setting Measurement Upper Limit: Approximately 9900 - 10100 μm (varies with fine focus adjustment) Measurement Lower Limit: Approximately 10000 - 10100 μm (varies with fine focus adjustment) Z - Measurement Distance Fixed: ON Z - Measurement Distance: Approximately 20 μm (varies with fine focus adjustment) Auto Upper / Lower Limit · Auto Brightness: OFF 〔Head〕 Head: R Objective Lens Name: Plan (CF IC EPI Plan 50X) Objective Lens Magnification: 50X Lens NA: 0.800 WD: 0.54 mm Image Plane Curvature Correction: ON Light Quantity Eccentricity Correction: ON Ring Illumination Correction: ON XY Calibration: 268.846 nm / pixel Z Calibration: 1.000 (0.100 nm / digit) 〔Camera Settings〕 Brightness Mode: Auto Brightness (Auto): Approximately 27 (varies with fine focus adjustment) Brightness (Manual): 1 Edge Enhancement: 5 〔Laser Settings〕 γ Coefficient (γ Correction Value): 0.45 γ Offset: 0% Black - and - White Inversion: OFF Edge Enhancement Type: None Edge Enhancement Direction: Vertical Edge Enhancement Strength: Weak 〔Other Condition Settings Shown in the Worksheet〕 Measurement Mode: Surface Shape Optical Zoom Magnification: 1.0x Filter: OFF Camera Gain: 0 dB Shutter speed: Auto White balance mode: Manual White balance R: 0 White balance B: 0 Light reception light quantity correction mode: Gamma correction Head type: VK-X105 Vividness: 5 Contrast: 5 Brightness: 0 AI noise reduction: OFF Inclined surface noise filter: OFF 〔Analysis conditions〕 Image processing: Surface shape correction implemented (cutoff wavelength 0.08 mm) Surface roughness setting (filter setting) Filter type: Gaussian S-filter (low-pass filter): None F-operation (shape correction): None L-filter (high-pass filter): None Correction of end effect: ON

[0056] <Evaluation of necking occurrence> Using the test pieces of Example 5 and Comparative Example 2 after measuring the above-mentioned "arithmetic mean roughness Ra", it was evaluated whether necking occurred by bending forming (Figure 1). Specifically, a cross-section parallel to the rolling direction of the bent test piece after the measurement (the side surface of the test piece) was observed at a magnification of 500 times using a digital microscope (Keyence, VHX-6000) and photographed. Using the photographed photo, it was confirmed whether the contour of the outer part of the bent portion of the test piece was arc-shaped, and it was judged that necking occurred when the contour of the test piece was significantly depressed toward the arc center with respect to the arc.

[0057] As is clear from Table 1, in the case of each example where strain relief annealing was performed after finish rolling, the elongation at break was 5% or more and the n value was 0.0175 or more. On the other hand, in the case of Comparative Examples 1 and 2 where strain relief annealing was not performed after finish rolling, the elongation at break was less than 5% and the n value was less than 0.0175. The copper alloy of the example having such characteristics had a lower Ra than the copper alloy of the comparative example, and the bending streak (the surface of the bent portion of the sample) was smoother. Also, in the evaluation of the occurrence of necking, no necking was confirmed in the copper alloy of Example 5, but necking was confirmed in the copper alloy of Comparative Example 2. That is, it can be said that the copper alloy of the example has good bend formability. Furthermore, the copper alloy of each example had a 0.2% proof stress of 500 MPa or more and a conductivity of 67% IACS or more. Therefore, the copper alloy of each example had good bend formability while maintaining high strength and high conductivity.

Industrial Applicability

[0058] According to the present disclosure, it is possible to provide a copper alloy with improved bend formability and an electronic component containing the same.

Claims

1. Contains 0.50 to 3.0 mass % Co, 0.10 to 1.0 mass % Si, and the balance being Cu and unavoidable impurities; The 0.2% yield strength is 500 MPa or more and 623 MPa or less, The breaking elongation measured by the following method is 5% or more, A copper alloy having a work hardening coefficient of 0.0175 or more and 0.0639 or less, as calculated by the following method. Breaking elongation: A tensile test is carried out using a JIS-13B test piece at a tensile speed of 5 mm / min. Work hardening coefficient: A tensile test is performed in accordance with JIS-Z2253 (2011). When a strain that is 0.005 smaller than the nominal strain (ε) at the maximum stress is defined as the initial strain (ε0), the slope of the log true stress - log true strain curve in the range of ε0 to ε is defined as the work hardening coefficient.

2. The copper alloy according to claim 1, having a 0.2% yield strength of 550 MPa or more and 623 MPa or less.

3. 3. The copper alloy according to claim 1 or 2, having an electrical conductivity of 30% IACS or more.

4. 3. The copper alloy according to claim 1, wherein the crystal grain size is 10 μm or less.

5. 3. The copper alloy according to claim 1, wherein the elongation at break is 10% or less.

6. 6. The copper alloy of claim 5, wherein the elongation to break is greater than or equal to 5.6% and less than or equal to 9.6%.

7. The copper alloy according to claim 1 or 2, having a thickness of 0.020 mm or more and 0.400 mm or less.

8. The copper alloy according to claim 1 or 2, further containing 0.005 to 0.80 mass% in total of at least one element selected from the group consisting of Mg, Fe, P, Mn, Zn, Ni and Cr.

9. A copper alloy as described in claim 1 or 2, having an arithmetic mean roughness Ra of 0.245 μm or less after the bending test described below. Bending test: A W-bending test is performed in accordance with JBMA T307: 1999, with an inner radius r of 0 mm and a sample width of 10 mm. The bending direction is perpendicular to the rolling direction, the test load is 50 kN, and the test speed is 5 m / min.

10. The copper alloy according to claim 9, wherein the arithmetic mean roughness Ra is 0.200 μm or more.

11. An electronic component comprising the copper alloy according to claim 1 or 2.

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