Copper alloy sheet

Abstract

A copper alloy sheet which contains 1.2-3.0 mass% of Ni, 0.10-1.0 mass% of Si, and 0.01-3.0 mass% of Zn, with the remainder comprising Cu and unavoidable impurities, and in a cross section in the thickness direction, the total area ratio of a portion having a CI value of less than 0.1 in an EBSD measurement in a range from the surface to a depth of 10% of the sheet thickness is 10.0-60.0%.

Description

Technical Field

[0001] The present invention relates to a copper alloy plate, and more particularly to a copper alloy plate having high yield strength and excellent bending workability. Background Art

[0002] Copper alloys for electrical and electronic components are required to have high electrical conductivity, high yield strength (yield stress), high tensile strength, excellent bending workability, excellent fatigue resistance, excellent stress relaxation resistance, and a high Young's modulus. To achieve these characteristics, the metallurgical structure of copper alloy sheets is controlled.

[0003] In particular, it was difficult to achieve both high strength (high yield strength and high tensile strength) and excellent bending workability, so various attempts at improvement were made.

[0004] Patent Documents 1 to 4 disclose the introduction of a KAM value as an indicator of dislocation density of a copper alloy sheet. By setting the KAM value to 1.0 to 3.0, a balance between the strength and bendability of the copper alloy sheet can be achieved.

[0005] The KAM value is the average of the dislocation density present in the metal structure within the measurement range.

[0006] Patent Document 5 discloses that by reducing shear bands near the surface of a copper alloy plate, a copper alloy plate having excellent bending workability and a wrinkle-free bent portion appearance can be obtained without reducing physical properties such as yield strength.

[0007] A shear band is a structure where deformation is locally concentrated. This means it is difficult to deform compared to the surrounding structure due to the accumulation of significant strain and increased dislocation density. Therefore, materials with shear bands are susceptible to uneven stretching from the shear bands during bending, leading to wrinkles and cracks. On the other hand, if rolling is not performed before shear bands form, work hardening will not occur, and the required alloy strength cannot be achieved.

[0008] Patent Document 5 focuses on the distribution of shear bands and proposes that the bending workability can be improved by reducing the number of shear bands near the surface of a copper alloy plate and increasing the number of shear bands in the interior.

[0009] Patent Document 6 discloses that a copper alloy plate having excellent stamping workability, bending workability, and strength can be obtained by setting the extreme density of the shear aggregate structure from the surface of the copper alloy plate to a depth of 5 μm to 2 to 8.

[0010] Typically, during cold rolling, the surface of a copper alloy sheet, which is in contact with the rolls, and the center of the sheet develop different microstructures. This is because friction with the rolls causes shear deformation in the surface. Patent Document 6 refers to this surface microstructure as surface microstructure (shear microstructure).

[0011] The extreme density of the shear aggregate structure is obtained by macroscopically measuring the crystal orientation of the copper alloy plate using X-ray diffraction.

[0012] In addition, Patent Documents 7 to 9 disclose the KAM value of copper alloy plates and the physical properties related thereto.

[0013] Patent Documents 7 and 8 describe the relationship between the KAM value, an index of dislocation density of a copper alloy plate, and corrosion due to etching.

[0014] Patent Document 9 discloses that excellent fatigue resistance can be exhibited by setting the Goss orientation density measured by the EBSD method to 2.0 to 6.0% and the average KAM value to 0.9 to 1.5°.

[0015] Prior art literature

[0016] Patent Literature

[0017] Patent Document 1: Japanese Patent No. 5690170

[0018] Patent Document 2: Japanese Patent No. 5314663

[0019] Patent Document 3: Japanese Patent No. 5476149

[0020] Patent Document 4: International Publication No. 2013 / 018228

[0021] Patent Document 5: Japanese Patent No. 5281031

[0022] Patent Document 6: Japanese Patent Application Laid-Open No. 2010-222618

[0023] Patent Document 7: Japanese Patent No. 06154565

[0024] Patent Document 8: Japanese Patent No. 06152212

[0025] Patent Document 9: Japanese Patent No. 05192536 Summary of the Invention

[0026] Problems to be solved by the invention

[0027] In the automotive field, the number of electronic devices installed is increasing, driven by compliance with environmental regulations, the pursuit of comfort and safety, and, more recently, the development of advanced driver assistance systems based on CASE (Connected, Autonomous, Shared & Services, Electric). Consequently, there is a demand for further miniaturization of components such as terminals, connectors, and relays. To manufacture these miniaturized components, it is necessary to maintain a yield strength comparable to that described in Patent Documents 1 to 6 while achieving superior bendability (particularly conformable bendability).

[0028] Patent Documents 7 to 9 do not disclose a method for improving bending workability and yield strength.

[0029] An object of an embodiment of the present invention is to provide a copper alloy sheet capable of achieving high yield strength and excellent bending workability.

[0030] Means of solving the problem

[0031] A first aspect of the present invention is a copper alloy plate comprising:

[0032] Ni: 1.2-3.0% by mass;

[0033] Si: 0.10-1.0% by mass;

[0034] Zn: 0.01-3.0 mass%

[0035] The balance contains Cu and unavoidable impurities.

[0036] In the EBSD measurement of the range from the surface to a depth of 10% of the plate thickness in the cross section in the thickness direction, the total area ratio of the portion with a CI value less than 0.1 is 10.0 to 60.0%.

[0037] A second aspect of the present invention is the copper alloy plate according to the first aspect, further comprising one or more of Sn and Mg in the range of Sn: higher than 0 mass % and 1.0 mass % or lower, and Mg: higher than 0 mass % and 0.2 mass % or lower.

[0038] A third aspect of the present invention is a copper alloy plate according to aspect 1 or 2, further comprising one or more selected from the group consisting of Al, Mn, Cr, Ti, Zr, Fe, P, and Ag in a total amount exceeding 0 mass % and not exceeding 0.5 mass %.

[0039] Effects of the Invention

[0040] According to the embodiment of the present invention, a copper alloy sheet that can achieve high yield strength and excellent bending workability can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1A This is a schematic cross-sectional view of the jig used in the bonding bending test.

[0042] Figure 1B This is a schematic cross-sectional view of the jig used in the bonding bending test.

[0043] Figure 1C This is a schematic cross-sectional view of the jig used in the bonding bending test.

[0044] Figure 2A This is an optical microscope photograph of a cross section (observation surface) of a sample piece subjected to a bonding and bending test.

[0045] Figure 2B This is an optical microscope photograph of a cross section (observation surface) of a sample piece subjected to a bonding and bending test. DETAILED DESCRIPTION

[0046] This embodiment effectively utilizes shear bands as a processed structure to provide a Cu—Ni—Si based copper alloy sheet having high yield strength and excellent bending workability.

[0047] A "shear band" is a structure where deformation is locally concentrated, i.e., where strain accumulates significantly and dislocation density increases. Generally speaking, the development of shear bands is believed to reduce the elongation of copper alloy sheets and impair bendability. Therefore, reducing the finishing ratio during cold rolling to suppress shear bands is considered effective in improving bendability. However, low finishing ratios do not produce high yield strength, making it difficult to achieve both high yield strength and excellent bendability (in other words, improving the yield strength-bendability balance).

[0048] As a result of intensive research, the present inventors have found that in a Cu-Ni-Si copper alloy plate having a specified chemical composition, by controlling the area ratio of the portion containing the shear band in the observation area near the surface, a copper alloy plate with an excellent yield strength-bending workability balance can be obtained.

[0049] In this embodiment, the CI (Confidence Index) value of the EBSD measurement is used as an indicator of shear bands. The CI value indicates the presence of localized dislocations (the presence of shear bands) at the measurement point. By measuring the entire measurement range at multiple points and determining the presence of dislocations at each point, the proportion (area ratio) of the area containing dislocations within the measurement range can be determined.

[0050] Furthermore, as an indicator of dislocations other than the CI value, there is the KAM value used in Patent Documents 1 to 4 and 7 to 9. The KAM value in Patent Documents 1 to 4 and 7 to 9 calculates the average number of dislocations within the measurement range, rather than measuring the presence or absence of localized dislocations. Therefore, the KAM value differs significantly from the CI value of this embodiment in that it does not measure the area ratio of the portion containing dislocations.

[0051] Furthermore, the measurement of the extreme density of the shear aggregate structure in Patent Document 6 is based on macroscopic measurement of the crystal orientation of the copper alloy plate by X-ray diffraction, and the presence or absence of local dislocations cannot be determined.

[0052] Hereinafter, the chemical composition, structure, and manufacturing method of the copper alloy plate according to the present embodiment will be described.

[0053] 1. Chemical composition

[0054] (1) Ni: 1.2-3.0 mass%

[0055] The Ni content is 1.2 to 3.0 mass %.

[0056] Ni, along with Si, precipitates Ni-Si compounds during aging, resulting in high strength and high electrical conductivity. Ni content below 1.2% by mass is inappropriate because the effect is minimal. Ni content exceeding 3.0% by mass is inappropriate because coarse compounds are formed during hot rolling or solution treatment, reducing bendability.

[0057] The lower limit of Ni is preferably 1.3% by mass, more preferably 1.35% by mass, and the upper limit of Ni is preferably 2.5% by mass, more preferably 2.0% by mass.

[0058] (2) Si: 0.10-1.0 mass%

[0059] The Si content is 0.10 to 1.0 mass %.

[0060] As mentioned above, Si, along with Ni, precipitates Ni-Si compounds during aging, thereby achieving high strength and high conductivity. A Si content of less than 0.10 mass% is inappropriate because the effect is minimal. A Si content exceeding 1.0 mass% is also inappropriate because coarse compounds are formed during hot rolling or solution treatment, reducing bendability.

[0061] The lower limit of Si is preferably 0.15 mass %, more preferably 0.20 mass %, and the upper limit of Si is preferably 0.80 mass %, more preferably 0.60 mass %.

[0062] (3) Zn: 0.01-3.0 mass%

[0063] The Zn content is 0.01 to 3.0 mass %.

[0064] The addition of Zn reduces stacking fault energy and promotes the formation of deformation twins during tensile rolling, which is expected to increase the strength of the copper alloy sheet. Furthermore, the addition of Zn improves the thermal peeling resistance of the solder and Sn plating. However, Zn additions exceeding 3.0 mass% are not recommended because they reduce solder wettability. Zn additions below 0.01 mass% are not recommended because they inadequately improve the thermal peeling resistance of the solder and Sn plating.

[0065] The lower limit of Zn is preferably 0.15 mass %, more preferably 0.30 mass %, and further preferably 0.50 mass %, and the upper limit of Zn is preferably 2.0 mass %, and more preferably 1.5 mass %.

[0066] (4) Margin

[0067] In a preferred embodiment, the balance is Cu and inevitable impurities. As inevitable impurities, the contamination of trace elements introduced due to conditions of raw materials, materials, production equipment, etc. is allowed.

[0068] The copper alloy plate is not limited to this embodiment, and may contain any other elements as long as the properties of the copper alloy plate of the present invention are maintained.

[0069] (5) Containing one or more of Sn and Mg in the following ranges: Sn: more than 0 mass% and less than 1.0 mass%, Mg: more than 0 mass% and less than 0.2 mass%

[0070] When Sn is added, the content of Sn is preferably higher than 0 mass % and 1.0 mass % or less.

[0071] The addition of Sn is expected to increase the strength of the copper alloy plate due to solid solution strengthening and improve its stress relaxation resistance. To achieve these effects, the Sn content is preferably greater than 0% by mass. Furthermore, by setting the Sn content to 1.0% by mass or less, the required electrical conductivity of the copper alloy for terminals can be maintained at a high level.

[0072] The lower limit of Sn is more preferably 0.005 mass %, further preferably 0.01 mass %, and particularly preferably 0.05 mass %, while the upper limit of Sn is more preferably 0.7 mass %, and further preferably 0.5 mass %.

[0073] When Mg is added, the Mg content is preferably higher than 0 mass % and not more than 0.2 mass %.

[0074] The addition of Mg is expected to increase the strength of the copper alloy sheet due to solid solution strengthening and improve stress relaxation resistance. To achieve these effects, the Mg content is preferably higher than 0% by mass. Furthermore, by setting the Mg content to 0.2% by mass or less, the required electrical conductivity of the copper alloy for terminals can be maintained at a high level.

[0075] The lower limit of Mg is more preferably 0.005 mass %, further preferably 0.01 mass %, and particularly preferably 0.05 mass %. The upper limit of Mg is preferably 0.17 mass %, and more preferably 0.15 mass %.

[0076] (6) One or more selected from the group consisting of Al, Mn, Cr, Ti, Zr, Fe, P and Ag, with the total amount exceeding 0% by mass and not exceeding 0.5% by mass

[0077] The addition of these elements is expected to increase the strength of the copper alloy plate due to solid solution strengthening and improve its stress relaxation resistance. To achieve these effects, the total content of these elements is preferably greater than 0% by mass. Furthermore, by keeping the total content of these elements below 0.5% by mass, the required electrical conductivity of the copper alloy for terminals can be maintained at a high level.

[0078] 2. Organization

[0079] The copper alloy plate of this embodiment is characterized by having a high number of shear bands in the metallurgical structure near the surface (high shear band number density). Specifically, when EBSD is performed on a cross-section in the thickness direction, from the surface of the copper alloy plate to a depth of 10% of the plate thickness, the total area ratio of portions with a CI value below 0.1 is controlled to be between 10.0 and 60.0%.

[0080] The metal structure of the outermost surface of a copper alloy plate is significantly affected by bending strain, which in turn affects its bendability. Therefore, the present inventors believe that measuring the shallow layer near the surface can help understand the bendability of the copper alloy plate. In this embodiment, the measurement range is from the surface of the copper alloy plate to a depth of 10% of the plate thickness.

[0081] The CI value obtained by EBSD is used as a method for evaluating the number density of shear bands. The CI value (Confidence Index) is a confidence index that indicates the reliability of crystal orientation and takes a value between 0 and 1. The CI value can be used to evaluate the quality of crystallinity at the observation point. Locations with concentrated deformation, such as shear bands, have lower CI values.

[0082] In this embodiment, when the CI value of a measurement point is less than 0.1, it is determined that a shear band has formed at this measurement point. EBSD measurement is performed over the entire measurement range, and the total area of ​​the portion with a CI value less than 0.1 is calculated (total area S2 (μm 2 )). Furthermore, the total area S2 (μm) in the measurement range for EBSD measurement is 2 ) relative to area S1 (μm 2 ) ratio (S2 / S1) is called the "total area ratio of the portion with a CI value lower than 0.1" or the "shear band amount".

[0083] The total area ratio (S2 / S1) of the portion with a CI value less than 0.1 ranges from 0 to 100%, with 0% being 0% when no shear band exists within the measurement range and 100% being 100% when shear bands exist in the metal structure throughout the measurement range.

[0084] In this embodiment, the bending workability is improved by controlling the total area ratio of the portion with a CI value less than 0.1 from the surface of the copper alloy plate to a depth of 10% of the plate thickness to 10.0 to 60.0%. The reason why the bending workability can be improved by controlling the total area ratio is uncertain, but the following mechanism is presumed.

[0085] During bending, tiny wrinkles form starting from shear bands. Since a large number of wrinkles occur, they are distributed to the bending strain. In other words, the concentration of bending strain on specific wrinkles is suppressed, which can prevent the growth of wrinkles and lead to cracking.

[0086] If the total area ratio of the portions with CI values ​​below 0.1 is less than 10.0%, the effect of suppressing the concentration of bending strain in individual wrinkles becomes weak, and cracks are more likely to occur. On the other hand, if the total area ratio exceeds 60.0%, shear bands become too dense, thereby reducing bending workability.

[0087] The total area ratio of the portion having a CI value of less than 0.1 is preferably 20.0% or more, more preferably 30.0% or more, and preferably 50.0% or less.

[0088] The measurement of the CI value is performed as follows.

[0089] The copper alloy plate is cut along a plane perpendicular to the plate width near the center of the plate width, and the microstructure of this cut surface is observed. The EBSD measurement is performed on the area between the surface of the copper alloy plate and a depth of 10% of the plate thickness from the surface, with a dimension (width) of approximately 150 μm in the rolling direction. For example, if the plate thickness is 150 μm, the measurement area is 15 μm in the depth direction × 150 μm in the width direction = approximately 2250 μm. 2 .

[0090] BSD measurements were performed with a measurement step size of 0.05 μm or 0.025 μm over the aforementioned measurement range. EBSD data were analyzed using image analysis software to determine the CI value, and the shear band density was evaluated (calculation of the total area ratio of portions with a CI value less than 0.1).

[0091] 3. Manufacturing method

[0092] Next, the method for producing the copper alloy plate of the present invention will be described.

[0093] Copper alloy sheets can be manufactured by sequentially performing hot rolling, cold rolling, solution treatment, aging treatment, finish cold rolling, and low-temperature annealing. Cold rolling is not performed between solution treatment and aging treatment.

[0094] The copper alloy plate of the present invention is basically a rolled copper alloy plate, and strips obtained by slitting the rolled copper alloy plate in the width direction and coiling the rolled copper alloy plate and the like are also included in the copper alloy plate of the present invention.

[0095] (hot rolled, cold rolled)

[0096] First, a copper alloy ingot with the desired chemical composition is prepared. The ingot is heated at 900-1000°C for 30-300 minutes and then hot-rolled. It is then cold-rolled to the target thickness (e.g., 0.2-1 mm). The target thickness can be adjusted appropriately based on the finish rolling ratio and final thickness of the copper alloy sheet.

[0097] (Solution treatment)

[0098] Next, in solution treatment, the copper alloy plate is heated to 700-850°C at a heating rate of 80°C / s or higher, held at this temperature for 10-120 seconds, and then cooled at a cooling rate of 80°C / s or higher.

[0099] The conditions for the solution treatment are different from those in Patent Document 2 in that the heating rate is extremely fast and the holding time is short.

[0100] (Aging treatment)

[0101] After solution treatment, the copper alloy plate is heated to 400-500°C at a heating rate of 40-80°C / hour and held at this temperature for 2-7 hours (hr). The plate is then cooled at a cooling rate of 20-60°C / hour. This treatment causes Ni-Si aging precipitation (aging treatment).

[0102] Furthermore, this method differs from Patent Document 7 in that no rolling is performed between the solution treatment and the aging treatment, and that the heat treatment time for the aging treatment is short.

[0103] (Fine cold rolling)

[0104] After the aging treatment, the copper alloy sheet produced under the above conditions is subjected to finish cold rolling at a reduction ratio of 40 to 80%.

[0105] When metal materials are deformed by finish cold rolling, they experience slip and shear deformation. The formation of precipitates in the matrix increases the material's resistance to deformation and suppresses slip deformation. Therefore, by performing finish cold rolling after aging precipitation occurs during the aging treatment, shear deformation is accelerated, effectively introducing shear bands. If the reduction ratio during finish cold rolling (referred to as the "finishing ratio") is less than 40%, the introduction of shear bands is insufficient, reducing bendability.

[0106] On the other hand, if the finishing rate exceeds 80%, excessive shear bands are introduced, thereby reducing bendability. By setting the finishing rate to 40-80%, appropriate shear bands can be introduced, improving bendability.

[0107] The lower limit of the finishing rate is preferably 45%, more preferably 50%, and is preferably appropriately set depending on the solutionizing conditions and aging conditions before finish cold rolling.

[0108] (Low temperature annealing)

[0109] After finish cold rolling, low-temperature annealing is performed to reduce the residual stress of the sheet and improve the elastic limit and stress relaxation resistance. The heating temperature at this time is preferably 250-450°C. By annealing at such a low temperature, the residual stress inside the sheet can be reduced, and the bending workability and elongation at break can be improved with almost no reduction in strength. In addition, the electrical conductivity can also be increased. In addition, if the heating temperature during low-temperature annealing is higher than the upper limit temperature of the heating temperature for aging treatment (500°C), it will soften significantly. Therefore, the upper limit of the heating temperature during low-temperature annealing is set to 450°C. On the other hand, when the heating temperature is lower than 250°C, the improvement effect of the above-mentioned various characteristics is difficult to fully manifest.

[0110] Those skilled in the art who have come into contact with the method for producing the copper alloy plate according to the embodiment of the present invention described above may be able to obtain the copper alloy plate of the present invention by a production method different from the above-described production method through repeated trials.

[0111] Example

[0112] (Production of copper alloy plates)

[0113] Copper alloy ingots (45 mm thick) were produced using an induction furnace, targeting the composition shown in Table 1. After heating the ingots at 950°C for at least 30 minutes, they were hot-rolled to a thickness of approximately 20 mm and water-cooled to produce hot-rolled plates. The hot-rolled plates were then surface-milled to remove surface oxide scale and cold-rolled to a thickness of approximately 2 mm. Subsequently, pre-rolling (cold rolling), solution treatment, aging treatment, finish cold rolling, and low-temperature annealing were performed in this order under the processing and heat treatment conditions shown in Table 2, yielding copper alloy plate samples with a thickness of approximately 0.15 mm (150 μm).

[0114] In addition, the heating rate of the solution treatment is 80°C / second or more, and the cooling rate is 80°C / second or more. The heating rate of the aging treatment is 40-80°C / hour, and the cooling rate is 20-60°C / hour.

[0115] (Organization Observation)

[0116] The copper alloy plate sample was sectioned near the center of the plate width and perpendicular to the plate width, and the microstructure of this cut surface was observed. The copper alloy plate was first sectioned, then embedded in resin and prepared for observation. The observation surface was prepared using a cross-section polisher (SM-09010, manufactured by JEOL Ltd.) after mechanical grinding and cloth wheel grinding. EBSD was used to measure the surface of the prepared observation surface, from the surface of the copper alloy plate to a depth of 15 μm (equivalent to 10% of the plate thickness), with a measurement range of approximately 150 μm in the rolling direction (width).

[0117] EBSD measurements were performed using a ZEISS Ultra55 within the aforementioned measurement range, with a measurement step size of 0.05 μm or 0.025 μm. Assuming a grid with grid points as measurement points, the total area ratio (%) was calculated as the ratio (X2 / X1) of the number of measurement points (grid points) with a CI value less than 0.1 (X2) to the total number of measurement points (grid points) within the measurement range (X1). The resulting total area ratio is reported as "shear band amount" in Table 3.

[0118] The CI value at each measurement point was determined by analyzing EBSD data using image analysis software (OIM, manufactured by TSL Solutions). When analyzing EBSD data using OIM, the measurement parameter (Number of Bands) / (Maximum Number of Bands) was converted into a CI value for analysis.

[0119] (Characteristics evaluation)

[0120] The copper alloy sheet samples were evaluated by measuring tensile strength (0.2% yield strength in the TD direction), electrical conductivity, and lamination flexibility.

[0121] Tensile test:

[0122] Test pieces for tensile testing were made from copper alloy plate samples and used for tensile testing.

[0123] Tensile testing was conducted using JIS No. 5 test pieces with the longitudinal direction perpendicular to the rolling direction. Shimadzu Corporation's AG-IS (100 kN) was used at room temperature, a test speed of 5 mm / min, and a test point distance of 50 mm to measure the 0.2% yield strength (MPa). Tensile test results indicated that a 0.2% yield strength (YS) in the direction perpendicular to rolling (TD) of 670 MPa or greater was considered acceptable, 720 MPa or greater was considered good, and 750 MPa or greater was considered excellent.

[0124] Electrical conductivity:

[0125] A test piece for measuring conductivity was prepared from the copper alloy plate sample, and the conductivity was measured.

[0126] Electrical conductivity was calculated using a test piece measuring 10 mm wide by 180 mm long, with the vertical length perpendicular to the rolling direction, using a double-arm bridge resistance meter (Huanghe Measurement Co., Ltd., 275200). The conductivity was then calculated using the average cross-sectional area method. A conductivity of 37% IACS or higher was considered high.

[0127] Fitting flexure:

[0128] The bonding bending test of the copper alloy plate samples was carried out by the following method.

[0129] Samples cut from copper alloy plate samples with dimensions of 10 mm in the rolling direction x 10 mm in the plate width were ground to a thickness of approximately 0.1 mm by single-side grinding. GoodWay (bending axis at right angles to the rolling direction) bonding bending tests were performed with the ground surface facing the inside of the bend.

[0130] In the fitting bending test, a V-shaped bending fixture ( Figure 1A Symbols 11, 12, and Figure 1B Symbols 21, 22), and block fixtures ( Figure 1C First, clamp the ground test piece S between Figure 1A The clamps 11 and 12 are bent to R = 0.05, θ = 90° with a load of 200N, and then clamped. Figure 1B The test piece S bent into a V-shape is clamped between the clamps 21 and 22 as shown in the figure. Figure 1CThe block-shaped jigs 31 and 32 shown above are compressed with a load of 200 N to be bent in contact with each other.

[0131] The bending properties of the bend are determined by observing the cross section of the bend to see if there are any cracks. Among the surfaces of the bend, the surface facing each other when the bend is bent is the "inner surface" and the surface opposite to the inner surface is the "outer surface" (see Figure 2A 、 Figure 2B ). Fitting the bendability, according to the bend ( Figure 2A 、 Figure 2B The determination is made by checking whether there are cracks on the outer side of the sample (the part surrounded by the dotted line in the figure).

[0132] A test piece subjected to bonded bending (bend test piece) was embedded in resin and prepared by mechanical grinding and polishing with a cloth wheel, with the cross section (observation surface) perpendicular to the bending axis. The cross section (observation surface) was observed using an optical microscope (magnification: ×200) to determine the presence of cracks on the outer surface of the bent portion. "Cracks" are observed as fine cracks extending from the outer surface of the bent portion toward the interior of the specimen.

[0133] Figure 2A In the example shown (sample No. 1), no cracks were observed on the outer side surface of the bent portion, and the sample was judged as "bonding is acceptable (○)". Figure 2B In the example shown (sample No. 7), cracks were observed on the outer side of the bent portion, resulting in a judgment of "bonding bending failure (×)". The judgment results are shown in the "GW bonding bending performance" column in Table 3.

[0134]

Table 1

[0135]

[0136]

Table 2

[0137]

[0138]

Table 3

[0139]

[0140] Samples No. 1 to 6, as examples of the invention, possessed the chemical composition and sufficient shear banding specified in this embodiment, resulting in high yield strength and excellent GW bonding bendability, resulting in copper alloy sheets with an excellent yield strength-bendability balance. Furthermore, the copper alloy sheets of Samples No. 1 to 6 possessed high electrical conductivity, making them suitable for use in electrical and electronic components without any problems.

[0141] In Comparative Examples, Samples No. 7 and 8 had shear band amounts outside the range specified in the present embodiment, resulting in low GW bonding bendability and cracking.

[0142] Industrial applicability

[0143] The copper alloy sheet of the present invention has high strength and excellent GW bonding bendability, and is therefore suitable for mating terminals and other terminal materials for automotive applications, as well as current-carrying parts of electrical and electronic components such as relays, switches, and sockets.

[0144] This application claims priority based on Japanese Patent Application No. 2023-027680, filed on February 24, 2023, which is incorporated herein by reference.

Claims

1. A copper alloy plate comprising Ni: 1.2-3.0 mass%, Si: 0.10-1.0 mass%, Zn: 0.01-3.0 mass% The balance contains Cu and unavoidable impurities. In EBSD measurement of a range from the surface to a depth of 10% of the plate thickness in a cross section in the thickness direction, the total area ratio of portions having a CI value of less than 0.1 is 10.0 to 60.0%.

2. The copper alloy plate according to claim 1, wherein Furthermore, Sn: more than 0 mass % and less than 1.0 mass %, Mg: One or more of Sn and Mg is contained in a range of more than 0 mass % and 0.2 mass % or less.

3. The copper alloy plate according to claim 1 or 2, wherein Furthermore, at least one selected from the group consisting of Al, Mn, Cr, Ti, Zr, Fe, P, and Ag is contained in a total amount in a range of more than 0 mass % and 0.5 mass % or less.

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