Cu-Ni-Si-BASED COPPER ALLOY SHEET, METHOD FOR PRODUCING THE SAME, CONDUCTIVE COMPONENT, AND HEAT-DISSIPATING COMPONENT

Abstract

To provide a Cu-Ni-Si-based copper alloy sheet that exhibits excellent bendability and fatigue properties and can be produced by a process with reduced manufacturing cost.SOLUTION: A copper alloy sheet has a chemical composition comprising, in mass%, Ni of 2.00 to 5.10%, and Si of 0.30 to 1.20%, and optionally containing one or more of Ag, Al, B, Co, Cr, Fe, Mg, Mn, Nb, P, S, Sn, Ti, Zn, Zr and rare-earth elements, with the balance being Cu and inevitable impurities. In measurement by EBSD (Electron Backscatter Diffraction) with a step size of 0.05 μm in a measurement region provided on a cross section perpendicular to the rolling direction, a KAM value is 3.00° or less when a boundary with a crystal orientation difference of 5° or more is regarded as a grain boundary. The number density of large precipitate particles having a major axis of 0.15 μm or more and 2.00 μm or less on a cross section parallel to the rolling surface is 5.0×104 particles / mm2 or more. The tensile strength in the direction perpendicular to the rolling direction is 500 MPa or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a Cu-Ni-Si alloy sheet having excellent fatigue properties, and to an electric-conducting part and a heat-dissipating part using the same, and also to a method for producing the Cu-Ni-Si alloy sheet by a process that omits solution treatment and aging treatment. [Background technology]

[0002] Cu-Ni-Si copper alloys (so-called Corson alloys) and Cu-[Ni,Co]-Si copper alloys in which part or all of the Ni is replaced with Co (hereinafter, these types of alloys will be collectively referred to as "Corson copper alloys") have a relatively good balance of strength and electrical conductivity among copper alloys, and are useful for current-carrying parts such as connectors and lead frames, and heat-dissipating parts for electronic devices, etc. To date, studies have been conducted to improve the various properties of Corson copper alloy sheets by controlling the texture and precipitate distribution, etc.

[0003] For example, Patent Document 1 discloses a technique for improving the press-punchability and etchability of a Co-containing Corson copper alloy by optimizing the texture. It also describes the use of a process that does not involve solution treatment. There is no teaching about improving bending workability or fatigue properties.

[0004] Patent Document 2 discloses a technique for improving the strength and bending workability of a Corson copper alloy containing Co by optimizing the texture, but does not teach the improvement of fatigue properties or the adoption of a process that omits solution treatment.

[0005] Patent Document 3 discloses a technique for improving the surface roughness of the outer periphery of a bent portion of a Corson copper alloy by forming a structure composed of crystal grains with little residual stress. There is no teaching about improving fatigue properties or adopting a process that omits solution treatment.

[0006] Patent Document 4 discloses a technique for improving the plating properties, pressability, heat resistance, etc. of a Corson copper alloy by optimizing the dispersion form of precipitate particles and the cross-sectional shape of crystal grains. There is no teaching about improving bending workability and fatigue properties or adopting a process that omits solution treatment. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2018-178243 A [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-95976 [Patent Document 3] Japanese Patent Application Publication No. 2023-100244 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-95185 Summary of the Invention [Problem to be solved by the invention]

[0008] Recently, there has been an increasing demand for smaller and thinner electronic components. To meet these demands and obtain highly reliable components, it is also important to improve the fatigue properties of the copper alloy sheet material used. Meanwhile, when processing copper alloy sheet material into current-carrying or heat-dissipating components, it is common for the material to go through a bending process. Therefore, when improving fatigue properties, care must be taken to ensure that bending workability is not compromised. Furthermore, in order to increase the cost competitiveness of electronic devices, it is necessary to establish technology for manufacturing high-performance materials at low cost.

[0009] In Corson copper alloys, precipitation strengthening is commonly used to increase strength. This typically requires solution treatment and aging treatment. Solution treatment generally requires the alloy to pass through the precipitation temperature range quickly during the cooling process. In the production of Corson copper alloy sheets, a high-temperature, short-time solution treatment is often performed using a continuous annealing furnace. Because operating a continuous annealing furnace at high temperatures is expensive, the production cost of the sheets can be significantly reduced by applying a process that omits the solution treatment. As shown in Patent Document 1, there are known examples of Corson copper alloy sheets that employ a manufacturing process that omits the solution treatment. However, according to the inventors' investigations, it is difficult to maintain high bending workability using the method of Patent Document 1.

[0010] The present invention aims to provide a Corson copper alloy sheet having electrical conductivity equivalent to that of conventional Corson copper alloy sheets, and also having better bending workability and fatigue properties, and also aims to provide a manufacturing method suitable for obtaining the sheet by omitting a solution treatment. [Means for solving the problem]

[0011] As a result of research, the inventors have found that when a Corson copper alloy sheet is structured in such a way that large precipitate particles with a major axis of 0.15 μm or more and 2.00 μm or less, which do not contribute much to improving strength, are dispersed at a density greater than or equal to a predetermined level, and the strength level is adjusted to a predetermined level or more and the KAM value is adjusted to a predetermined level or less, the sheet can have electrical conductivity equivalent to that of conventional Corson copper alloy sheets while also achieving good bending workability and fatigue properties. Furthermore, they have found that a simple manufacturing process that omits solution treatment and aging treatment after optimizing annealing conditions and cold rolling conditions is suitable for producing such a sheet. Based on these findings, the present specification discloses the following invention.

[0012] [1] In mass%, Ni: 2.00-5.10%, Si: 0.30-1.20%, Ag: 0-0.30%, Al: 0-1.00%, B: 0-0.20%, Co: 0-1.0%, Cr: 0-0.50%, Fe: 0-1.00%, Mg: 0-0.50%, Mn: 0-1.00%, Nb: 0-1.00%, P: 0-0.20%, S: 0-0.20%, Sn: 0-1.00%, Ti: 0-0.50%, Zn: 0-1.00%, Zr: 0-0.30%, rare earth elements: 0-3.00% in total, the balance being Cu and unavoidable impurities. The chemical composition is such that the total content of Ag, Al, B, Co, Cr, Fe, Mg, Mn, Nb, P, S, Sn, Ti, Zn, Zr, and rare earth elements is 4.00% or less, and when a measurement area is measured on a cross section perpendicular to the rolling direction using EBSD (electron backscatter diffraction) with a step size of 0.05 μm, the KAM value is 3.00° or less when boundaries with a crystal orientation difference of 5° or more are considered to be grain boundaries, and the number density of large-diameter precipitate particles with a major axis of 0.15 μm or more and 2.00 μm or less on a cross section parallel to the rolling surface is 5.0 × 10 4 pieces / mm 2 and a copper alloy sheet material having a tensile strength of 500 MPa or more in a direction perpendicular to the rolling direction. [2] The number density of small precipitate particles with a major axis of 0.005 μm or more and less than 0.050 μm in a cross section parallel to the rolling surface is 5.0 × 10 6 pieces / mm 2 The copper alloy sheet material according to [1] above. [3] The copper alloy sheet material according to the above [1] or [2], wherein in the measurement by the EBSD with a step size of 0.05 μm, the average grain size is 4.00 μm or less by the Area Fraction method when boundaries with a crystal orientation difference of 5° or more are considered to be grain boundaries. [4] In a cross section parallel to the rolling surface, the number density of the large diameter precipitate particles is a (pieces / mm 2 ), and the number density of medium-sized precipitate particles with a major axis of 0.05 μm or more and less than 0.15 μm is defined as b (particles / mm 2 ) the copper alloy sheet material according to any one of the above [1] to [3], which satisfies the following formula (1): 0.01≦a / b≦0.30 …(1) [5] In the measurement by the EBSD with a step size of 0.05 μm, the KAM value when a boundary with a crystal orientation difference of 5° or more is considered to be a grain boundary is 1.50° or less, and the average crystal grain size by the Area Fraction method is 1.60 μm or more and 3.60 μm or less, and the number density of the large diameter precipitate particles in a cross section parallel to the rolled surface is 7.0 × 10 4 pieces / mm 2 and the number density of small-diameter precipitate particles with a major axis of 0.005 μm or more and less than 0.050 μm is 10.0 × 10 6 pieces / mm 2 The copper alloy sheet material according to the above [1] or [4].

[0013] [6] The copper alloy sheet material according to any one of the above [1] to [5], which has an electrical conductivity of 45% IACS or more. [7] The copper alloy sheet material according to any one of the above [1] to [6], wherein the ratio MBR / t of the minimum bending radius MBR at which cracking does not occur to the sheet thickness t in a 90°W bending test at BW in accordance with the Japan Copper and Brass Association technical standard JCBA T307:2007 is 2.0 or less. [8] In a reversed-swing fatigue test using a cantilever resonance method with a test piece whose longitudinal direction was perpendicular to the rolling direction, the fatigue limit at a load stress of 300 MPa was 1.0 × 10 5 The copper alloy sheet material according to any one of the above [1] to [7], which is 100 cycles or more.

[0014] [9] A method for producing a copper alloy sheet material according to any one of [1] to [8] above, When an unannealed hot-rolled material having the above chemical composition that has not been subjected to heat treatment after hot rolling is subjected to hot-rolled material annealing, intermediate cold rolling, intermediate annealing, finish cold rolling, and finish annealing in the above order to obtain a plate product, The hot-rolled material is annealed at a temperature of 400°C or higher and 650°C or lower for 5 hours or longer and 20 hours or shorter. Intermediate cold rolling is performed at a rolling reduction rate of 25% or more. The intermediate annealing is carried out under conditions of holding the temperature at 400°C or higher and 650°C or lower for 5 hours or higher and 20 hours or lower, The finish cold rolling is carried out under the condition of a rolling ratio of 39% or more and 95% or less, The final annealing is performed under the condition of heating to a temperature of 300°C or higher and 500°C or lower. Method for manufacturing a copper alloy sheet.

[10] The method for manufacturing a copper alloy sheet according to any one of [1] to [8] above, When obtaining a sheet product by subjecting an as-annealed hot-rolled material or as-annealed cold-rolled material having the above chemical composition, which has not been heat-treated after hot rolling, to intermediate annealing, final cold rolling, and final annealing in this order, The intermediate annealing is performed under the condition of holding at a temperature of 400°C or higher and 650°C or lower for 5 hours or more and 20 hours or less. The final cold rolling is performed under the condition of a rolling ratio of 34% or more and 90% or less. The final annealing is performed under the condition of heating to a temperature of 300°C or higher and 500°C or lower. Method for manufacturing a copper alloy sheet.

[0015]

[11] An electrical component using the copper alloy sheet according to any one of [1] to [8] above as a material.

[12] A heat radiating component using the copper alloy sheet according to any one of [1] to [8] above as a material.

[0016] In this specification, "sheet" means a sheet-like metal material. A thin sheet-like metal material may also be called "foil", and such "foil" is also included in the "sheet" referred to here. A long sheet-like metal material wound in a coil shape is also included in the "sheet". In this specification, the thickness of the sheet-like metal material is called "sheet thickness". Also, "sheet surface" means a surface perpendicular to the sheet thickness direction of the sheet. The sheet surface may also be called "rolling surface". In this specification, the notation "n₁~n₂" indicating a numerical range means "n₁ or more and n₂ or less". Here, n₁ and n₂ are numerical values satisfying n₁ < n₂.

[0017] The "major axis" of a particle is the length of the major axis when the particle is approximated as an ellipse on the image plane for large-diameter and medium-diameter precipitate particles, and is the maximum possible length of the line segment (limited to those with no portion extending outside the particle) connecting two points on the particle's outline on the image plane for small-diameter precipitate particles.

[0018] The rolling ratio (%) in a certain rolling process is determined by the following formula (2). Rolling ratio (%) = 100 × (h0 - h1) / h0…(2) h0: Plate thickness before the first pass of the rolling process (mm) h1: Plate thickness at the end of the final rolling pass of the rolling process (mm) [Effects of the Invention]

[0019] According to the present invention, it has been possible to realize a Corson copper alloy sheet material that has electrical conductivity equivalent to that of conventional Corson copper alloy sheets and that further achieves both good bending workability and fatigue properties. Since this sheet material can be produced by a simple process that omits solution treatment and aging treatment, the present invention can also contribute to reducing the production cost of the Corson copper alloy sheet material. DETAILED DESCRIPTION OF THE INVENTION

[0020] [Chemical composition] Hereinafter, "%" regarding the composition of components means "% by mass" unless otherwise specified.

[0021] Ni (nickel) and Si (silicon) form precipitates mainly composed of Ni2Si, which contribute to improving strength and electrical conductivity. They also contribute to improving fatigue properties. The Ni content can be set in the range of 2.00 to 5.10%, and the Si content can be set in the range of 0.30 to 1.20%. Within these ranges, appropriate strength, electrical conductivity, and fatigue properties, as described below, can be achieved. The mass ratio of Ni to Si, Ni / Si, is preferably 3.0 to 6.0, and more preferably 4.0 to 5.1.

[0022] As optional elements, one or more of Ag (silver), Al (aluminum), B (boron), Co (cobalt), Cr (chromium), Fe (iron), Mg (magnesium), Mn (manganese), Nb (niobium), P (phosphorus), S (sulfur), Sn (tin), Ti (titanium), Zn (zinc), Zr (zirconium), and rare earth elements may be contained as needed. The contents of these optional elements can be set within the following ranges: Ag: 0-0.30%, Al: 0-1.00%, B: 0-0.20%, Co: 0-1.0%, Cr: 0-0.50%, Fe: 0-1.00%, Mg: 0-0.50%, Mn: 0-1.00%, Nb: 0-1.00%, P: 0-0.20%, S: 0-0.20%, Sn: 0-1.00%, Ti: 0-0.50%, Zn: 0-1.00%, Zr: 0-0.30%, and rare earth elements: 0-3.00% in total. The total content of these optional elements is preferably 4.00% by mass or less to achieve a good balance of bending workability, strength, electrical conductivity, and fatigue properties.

[0023] Here, the rare earth elements are Sc (scandium), Y (yttrium), and lanthanoid elements (excluding Pm (promethium)) of Group 3 of the periodic table. Misch metal (a mixture of rare earth elements) may be used as a supply source of the rare earth elements.

[0024] Considering economic efficiency and manufacturability, the contents of the above optional elements are more preferably in the ranges of Ag: 0-0.20%, Al: 0-0.60%, B: 0-0.10%, Co: 0-0.60%, Cr: 0-0.30%, Fe: 0-0.60%, Mg: 0-0.40%, Mn: 0-0.75%, Nb: 0-0.60%, P: 0-0.10%, S: 0-0.10%, Sn: 0-0.60%, Ti: 0-0.30%, Zn: 0-0.75%, Zr: 0-0.20%, and rare earth elements: 0-2.00% in total. In this case, the total content of these elements is more preferably 2.50% by mass or less.

[0025] The contents of the above optional elements may be controlled within the following ranges: Ag: 0-0.10%, Al: 0-0.20%, B: 0-0.05%, Co: 0-0.40%, Cr: 0-0.15%, Fe: 0-0.30%, Mg: 0-0.30%, Mn: 0-0.50%, Nb: 0-0.40%, P: 0-0.05%, S: 0-0.02%, Sn: 0-0.30%, Ti: 0-0.10%, Zn: 0-0.50%, Zr: 0-0.10%, and rare earth elements: 0-0.70% in total. In this case, the total content of these elements is preferably controlled to 1.20% by mass or less.

[0026] The inclusion of elements other than those mentioned above is also permitted within a range that does not impair the objective of the present invention (achieving both good bending workability and fatigue properties). Specifically, the total content of elements other than Ni, Si, Ag, Al, B, Co, Cr, Fe, Mg, Mn, Nb, P, S, Sn, Ti, Zn, Zr, rare earth elements, and Cu (copper) (hereinafter sometimes referred to as "unspecified elements") is preferably 0.50% or less, and may be controlled to 0.10% or less. The content of unspecified elements can be determined, for example, by quantifying substantially all elements that may be contained in the copper alloy sheet material using the following analytical method.

[0027] (Example of a method for quantifying alloying elements) O (oxygen) and N (nitrogen) are quantified using an oxygen / nitrogen / hydrogen analyzer (e.g., LECO ONH-836), H (hydrogen) is quantified using a hydrogen analyzer (e.g., HORIBA EMGA-921), C (carbon) and S (sulfur) are quantified using a carbon-sulfur analyzer (e.g., LECO CS844), elements from the second to sixth periods (excluding C, N, O, Group 17 elements, Group 18 elements, Tc (technetium), Po (polonium), and Pm (promethium)) are quantified using ICP-MS (e.g., Agilent 7900), and F (fluorine), Cl (chlorine), and Br (bromine) are quantified using a combustion-ion chromatography system (e.g., Thermo Scientific DIONEX ICS-1600).

[0028] The chemical composition of the copper alloy sheet material according to the present invention can also be specified as follows. In mass%, Ni: 2.00~5.10%, Si: 0.30~1.20%, Ag: 0~0.30%, Al: 0~1.00%, B: 0~0.20%, Co: 0~1.0%, Cr:0~0.50%, Fe:0~1.00%, Mg:0~0.50%, Mn:0~1.00%, Nb:0~1.00%, P:0~0.20%, S:0~0.20%, Chemical composition: Sn: 0-1.00%, Ti: 0-0.50%, Zn: 0-1.00%, Zr: 0-0.30%, rare earth elements: 0-3.00% in total, Ni, Si, Ag, Al, B, Co, Cr, Fe, Mg, Mn, Nb, P, S, Sn, Ti, Zn, Zr, rare earth elements, elements other than Cu (non-specified elements): 0.50% in total or less, balance Cu In this case, the total content of the above non-specified elements is more preferably 0.10% or less, and may be controlled to 0.05% or less.

[0029] [Precipitate particles] In this specification, precipitate particles observed in the metal matrix (parent phase) of a Corson copper alloy are classified by size and defined as the following three types. Large precipitate particles: major axis 0.15 μm to 2.00 μm Medium-sized precipitate particles: major axis 0.05 μm or more and less than 0.15 μm Small diameter precipitate particles: major axis 0.005 μm or more and less than 0.050 μm Particles larger than the large diameter precipitate particles and particles smaller than the small diameter precipitate particles are not discussed here.

[0030] Large-sized precipitate particles contribute little to improving strength but do contribute to improving fatigue properties. Medium-sized precipitate particles are usually present at a higher number density than large-sized precipitate particles, but do not contribute much to improving strength or fatigue properties. Small-sized precipitate particles significantly contribute to improving strength, and their strength-improving effect can indirectly contribute to improving fatigue properties. In addition, for both of these particles, the greater the amount of precipitation, the greater the effect of improving electrical conductivity due to the reduction in solute atoms in the matrix.

[0031] In the present invention, the number density of large-diameter precipitate particles is set to 5.0 × 104 pieces / mm 2 or more. When the strength level is sufficiently high, the fatigue properties can be improved by adjusting the number density of large-diameter precipitate particles to the above range. Even if the number density of large-diameter precipitate particles is lower than the above range, it is possible to improve the fatigue properties by creating a structure with many small-diameter precipitate particles and large lattice strain. However, in this case, bending workability will be deteriorated. The number density of large-diameter precipitate particles is 5.1 × 10 4 pieces / mm 2 Over 55.0 x 10 4 pieces / mm 2 More preferably, it is:

[0032] The number density of small precipitate particles is 5.0 × 10 6 pieces / mm 2 In the case where the microstructure is in a state where an appropriate degree of processing strain has been introduced, high strength can be obtained by adjusting the number density to the above range. From the viewpoint of strength, the number density of small-diameter precipitate particles is preferably 7.5 × 10 6 pieces / mm 2 Over 500.0 x 10 6 pieces / mm 2 It is more preferable that the KAM value is 0.50° or more.

[0033] In a cross section parallel to the rolling surface, the number density of large-diameter precipitate particles is defined as a (particles / mm 2 ), and the number density of medium-sized precipitate particles is b (particles / mm 2 ), it is preferable that the structure state satisfies the following formula (1). 0.01≦a / b≦0.30 …(1) Within this range, a good balance between electrical conductivity and fatigue properties is easily achieved.

[0034] [How to determine the number density of large and medium-sized precipitate particles] The plate surface was electrolytically polished under the following electrolytic polishing conditions to dissolve only the Cu base of the copper alloy plate material, thereby exposing the precipitate particles, and then ultrasonically cleaned in ethanol for 20 minutes using an ultrasonic cleaner. The surface obtained was then observed using an FE-SEM (field emission scanning electron microscope) at an acceleration voltage of 15 kV and a magnification of 20,000 times, and the number of large-diameter precipitate particles (major diameter of 0.15 μm or more and 2.00 μm or less) and medium-diameter precipitate particles (major diameter of 0.05 μm or more and less than 0.15 μm) observed on the FE-SEM image was counted. The total number of large-diameter precipitate particles and medium-diameter precipitate particles counted was calculated based on the total observation area (mm 2 ) were divided by the number density (particles / mm 2 ) The total observation area is the sum of the areas of five randomly selected, non-overlapping observation fields. Precipitate particles that partially extend outside the observation field are counted if the portion that appears within the observation field is the entire particle and if their major diameter corresponds to a large-diameter precipitate particle or a medium-diameter precipitate particle. Measurement of the major diameter of the particles and counting the number of particles can be performed using image processing software (e.g., ImageJ). (Electrolytic polishing conditions) Electrolyte: Distilled water, phosphoric acid, ethanol, and 2-propanol mixed in a volume ratio of 10:5:5:1 Liquid temperature: 20℃ Voltage: 15V ·Electrolysis time: 20 seconds

[0035] [How to determine the number density of small diameter precipitate particles] The plate surface was electrolytically polished under the following electrolytic polishing conditions, and then ultrasonically cleaned in ethanol for 20 minutes using an ultrasonic cleaner. The surface was then observed using a FE-SEM (field emission scanning electron microscope) at an acceleration voltage of 15 kV and a magnification of 100,000 times. An observation field was randomly selected in which some or all of the particles with a major axis of 1.0 μm or more were not included. Within the observation field, the number of particles whose entire outlines were visible that fell under the category of small-diameter precipitate particles (major axis of 0.005 μm or more but less than 0.050 μm) was counted. The total number of particles counted was divided by the total area of ​​the observation field to determine the number density (particles / mm 2 ) (Electrolytic polishing conditions) Electrolyte: Distilled water, phosphoric acid, ethanol, and 2-propanol mixed in a volume ratio of 10:5:5:1 Liquid temperature: 20℃ Voltage: 15V ·Electrolysis time: 20 seconds

[0036] [KAM value] The copper alloy sheet material of the present invention is required to have a KAM value of 3.00° or less when a boundary with a crystal orientation difference of 5° or more is considered to be a grain boundary, as measured by EBSD (electron backscatter diffraction) with a step size of 0.05 μm in a measurement area provided on a cross section perpendicular to the rolling direction. The KAM value is an index that provides a clue to the extent of local lattice strain (residual stress) present in the sheet material as a whole. If the KAM value exceeds 3.00°, it becomes difficult to stably obtain good bending workability. The KAM value is more preferably 2.50° or less, and even more preferably 1.50° or less.

[0037] (How to calculate KAM value) Based on the above EBSD measurement data measured at a step size (measurement pitch) of 0.05 μm on a cross section perpendicular to the rolling direction, EBSD data analysis software is used to calculate the KAM (Kernel Average Misorientation) value, assuming that boundaries with a misorientation of 5° or more (including twin boundaries) are considered to be grain boundaries. This KAM value corresponds to the average value obtained by measuring all crystal orientation misorientations between adjacent electron beam irradiation spots arranged at a pitch of 0.05 μm (hereinafter referred to as "adjacent spot misorientation"), extracting only the measurements of adjacent spot misorientations that are less than 5°. Note that twin boundaries are also considered to be grain boundaries in calculating the KAM value.

[0038] [Average grain size] In the copper alloy sheet material of the present invention, the average grain size is preferably 4.00 μm or less when measured by the Area Fraction method in the above-mentioned EBSD measurement, assuming that boundaries with a crystal orientation difference of 5° or more are regarded as grain boundaries. The smaller this average grain size, the more advantageous it is for improving strength. There is no particular lower limit for the average grain size, but excessive refinement can lead to an increase in process load, so it is usually sufficient to control it to a range of 0.20 μm or more. A particularly preferred range for this average grain size is 1.40 μm or more and 3.60 μm or less.

[0039] (How to determine the average grain size) Based on the above EBSD measurement data, measured at a step size (measurement pitch) of 0.05 μm on a cross section perpendicular to the rolling direction, EBSD data analysis software was used to consider boundaries with a misorientation of 5° or more as grain boundaries. The grain sizes of all grains within the measurement area were determined using a diameter chart, and the average grain size was calculated using the area fraction method. For grains that partially extend beyond the boundaries of the measurement area, the area of ​​the portion within the measurement area was used to calculate the average grain size. Note that twin boundaries ({111} / Σ3 coincidence boundary, {110} / Σ9 coincidence boundary) were ignored and not considered as grain boundaries when calculating the average grain size.

[0040] [Tensile strength] For copper alloy sheet materials used in current-carrying components such as connectors and heat-dissipating components of electronic devices, it is desirable that the tensile strength in the direction perpendicular to the rolling direction be at a strength level of 500 MPa or more. Furthermore, when the tensile strength in the direction perpendicular to the rolling direction is 500 MPa or more, fatigue properties can be improved without impairing bending workability by optimizing the KAM value and the number density of large-diameter precipitate particles as described above. Therefore, the present invention targets sheet materials having a tensile strength in the direction perpendicular to the rolling direction of 500 MPa or more. It is also possible to adjust the tensile strength to 600 MPa or more, or 650 MPa or more. There is no particular upper limit for the tensile strength in the direction perpendicular to the rolling direction, but from the viewpoint of balance with bending workability, it is preferable to set it to, for example, 950 MPa or less, or 900 MPa or less. The direction perpendicular to the rolling direction is the direction perpendicular to the rolling direction and the sheet thickness direction.

[0041] [conductivity] Considering the use as a current-carrying part of an electronic device, the electrical conductivity is preferably 45% IACS or more, and more preferably 50% IACS or more. The electrical conductivity of the copper alloy sheet according to the present invention is usually in the range of 70% IACS or less.

[0042] [Bending workability] To ensure high reliability when processed into current-carrying or heat-dissipating components, it is desirable for the steel to have bending workability such that the ratio MBR / t of the minimum bending radius MBR at which cracks do not occur to the sheet thickness t is 2.0 or less in a BW W-bend test according to the Japan Copper and Brass Association technical standard JCBA T307:2007. It is more preferable for the MBR / t at BW to be 1.5 or less, and even more preferable for it to be 1.0 or less. It is also possible to obtain steel with an MBR / t at BW of 0.0 (no cracks occurring in tight bending). BW (Bad Way) means that the bending axis is parallel to the rolling direction.

[0043] JCBA T307:2007 states that "This standard applies to the evaluation of the bending workability of copper and copper alloy thin sheet strips with a thickness of 0.1 mm or more and 0.8 mm or less." The inventors' studies have confirmed that it is possible to evaluate the bending workability of Corson copper alloy sheets with a thickness of less than 0.1 mm by the W-bend test method described in the standard. Therefore, in the present invention, the BW W-bend test method described in JCBA T307:2007 is extended to cases with a thickness of less than 0.1 mm (for example, 0.02 mm or more and less than 0.1 mm) and is applied as is.

[0044] In addition, in measurements using EBSD with a step size of 0.05 μm, the KAM value when a boundary with a crystal orientation difference of 5° or more is considered to be a grain boundary is 1.50° or less, and the average grain size measured by the Area Fraction method is 1.60 μm or more and 3.60 μm or less, and the number density of the large-diameter precipitate particles in a cross section parallel to the rolled surface is 7.0 × 10 4 pieces / mm 2 and the number density of small-diameter precipitate particles with a major axis of 0.005 μm or more and less than 0.050 μm is 10.0 × 10 6 pieces / mm 2 The copper alloy sheet material of the present invention having the above-described properties is particularly excellent in balance of strength, electrical conductivity, and bending workability. 6 pieces / mm 2 It may be managed as follows:

[0045] [Fatigue properties] Since current-carrying parts such as connectors may be subjected to repeated stress, the use of a sheet material with good fatigue properties is advantageous for improving the reliability of the parts. Considering the applications of the copper alloy sheet material according to the present invention, in a reversed-swing fatigue test using a cantilever resonance method with a test piece whose longitudinal direction is the transverse direction (TD) of the rolling, the fatigue limit at a load stress of 300 MPa was 1.0 × 10 5 It is desirable that the fatigue limit is 5.0 × 10 cycles or more. 5 cycles or more, or 10.0 x 10 5It is also possible to adjust the fatigue limit to more than 70.0 × 10 cycles. The "fatigue" can be determined by monitoring the decrease in resonance frequency that accompanies the decrease in Young's modulus. In the copper alloy sheet material of the present invention, the fatigue limit is usually 70.0 × 10 5 cycles or less.

[0046] [Manufacturing method] The copper alloy sheet material described above can be typically produced by the following production process. Casting → Hot rolling → (annealing of hot-rolled material) → Intermediate cold rolling → Intermediate annealing → Finishing cold rolling → Finishing annealing Annealing of the hot-rolled material can be omitted. Although not described in the above steps, facing is performed as needed after hot rolling, and pickling, polishing, or further degreasing is performed as needed after each heat treatment. Each of the above steps will be explained below.

[0047] [Melting, Casting, Hot Rolling] A slab having the above-mentioned chemical composition is produced by continuous casting, semi-continuous casting, or the like. Hot rolling can be performed according to a conventional method. The slab can be heated before hot rolling, for example, by holding it at 900 to 1050°C for 1 to 5 hours. The total hot rolling reduction can be, for example, 70 to 97%.

[0048] [Hot-rolled material annealing] The hot-rolled material obtained by hot rolling, i.e., "unannealed hot-rolled material" that has not been subjected to any heat treatment after hot rolling, can be annealed as needed before being subjected to intermediate cold rolling. This annealing is called "hot-rolled material annealing." Hot-rolled material annealing can be omitted. When hot-rolled material annealing is performed, it is performed under conditions of holding the material at a temperature of 400°C to 650°C for 5 hours to 20 hours. Depending on the alloy composition and hot-rolling conditions, for example, if the hot-rolled material is relatively hard, adopting this process is advantageous from the perspective of reducing the load on the rolling mill during intermediate cold rolling.

[0049] [Intermediate cold rolling] Unannealed hot-rolled material or material that has undergone hot-rolled annealing can be cold-rolled at a reduction ratio of 25% or more. In this process, processing strain is imparted and the plate thickness is adjusted so that the formation of precipitates is promoted in the intermediate annealing described below. The cold-rolling reduction ratio in this process is preferably set in the range of 50% to 99%, and may also be controlled in the range of 70% to 99%. If sufficient processing strain remains in the hot-rolled material and the target product thickness can be adjusted by finish cold rolling alone, the hot-rolled annealing and this intermediate cold rolling may be omitted. In addition, when the material to be subjected to this intermediate cold rolling is an unannealed hot-rolled material, the cold-rolled material obtained by this intermediate cold rolling has never been subjected to heat treatment after hot rolling. Therefore, such a cold-rolled material is called an "unannealed cold-rolled material."

[0050] [Intermediate annealing] A cold-rolled material (including unannealed cold-rolled material) that has undergone intermediate cold rolling, or an unannealed hot-rolled material, is annealed by holding it at a temperature of 400°C or higher and 650°C or lower for 5 hours or longer and 20 hours or shorter. This allows large-diameter precipitate particles, medium-diameter precipitate particles, and small-diameter precipitate particles to be sufficiently generated.

[0051] [Finishing cold rolling] After intermediate annealing, the material is subjected to final cold rolling to achieve the desired thickness and to impart appropriate processing strain. In this process, the material that has undergone the hot-rolled annealing is cold-rolled at a rolling reduction of 39% to 95%, more preferably 40% to 90%. For materials that have not undergone the hot-rolled annealing, cold rolling is performed at a rolling reduction of 34% to 90%. If the rolling reduction is too low in this cold-rolling process, even if the abundance of large-diameter precipitate particles and small-diameter precipitate particles falls within the appropriate range, the final residual processing strain may be insufficient, resulting in insufficient improvement in strength and fatigue properties. Conversely, if the rolling reduction is too high, the final residual processing strain may be so great that the KAM value of the final product may exceed 3.00°. In this case, bending workability may be insufficient.

[0052] [Finishing annealing] After the finish cold rolling, the material is subjected to final annealing at a temperature of 300°C to 500°C in order to remove strain and improve bending workability. The holding time at this temperature can be set within the range of 5 seconds to 3600 seconds, for example. This heat treatment can be carried out using a continuous annealing furnace.

[0053] [About solution treatment] The method for producing a copper alloy sheet material of the present invention employs a process that can omit the solution treatment as described above, and is therefore more cost-effective than conventional methods for producing Corson copper alloy sheets. While solution treatment is usually followed by aging treatment (pre-aging cold rolling may be performed before aging treatment), the present invention does not require pre-aging cold rolling or aging treatment. Solution treatment is a heat treatment that dissolves precipitates in a material into the matrix, removes strain within the material, and induces recrystallization. For the alloy composition targeted by the present invention, the effect of solution treatment can be achieved by heating to a temperature range exceeding 650°C. By undergoing the above-described steps, the copper alloy sheet material of the present invention can be produced without heating to a temperature range exceeding 650°C in processes subsequent to hot rolling.

[0054] [Electrical and heat-dissipating parts] The copper alloy sheet material of the present invention obtained as described above has sufficient bending workability for processing into current-carrying parts such as connectors and heat-dissipating parts for electronic devices. In addition, the obtained parts also have good fatigue properties and achieve a good balance between strength and electrical conductivity equivalent to that of conventional techniques. [Example]

[0055] Copper alloys having the chemical compositions shown in Tables 1 to 4 were melted and cast slabs were obtained using a vertical semi-continuous casting machine. In No. 8, misch metal (a mixture of rare earth elements) was added as a source of rare earth elements at a ratio of 0.30 mass% of the total amount of copper alloy raw materials. The mass ratio of the main rare earth elements contained in this misch metal was La:Ce:Pr:Nd=28:50:5:17. Analysis samples taken from the cast slabs were analyzed for the elements listed in Tables 1 to 4 using the method described in the above section "Example of a method for quantifying alloying elements."

[0056] The slabs were held at the temperatures and times shown in Tables 1 to 4, and then hot-rolled at a final rolling temperature of 700°C or higher and water-cooled to obtain hot-rolled materials with thicknesses shown in Tables 1 to 4. The total reduction ratio in hot rolling was in the range of 89 to 96%. After hot rolling, the surface oxide layer was removed (face milled) by mechanical polishing and cutting, and then the steps shown in Tables 1 to 4 were carried out in order from top to bottom to obtain copper alloy sheet products with a thickness of 0.15 mm (except for No. 56, which had a thickness of 0.10 mm). Specifically, Nos. 1 to 10 and 41 to 48 adopted the process of hot rolling → hot-rolled material annealing → intermediate cold rolling → intermediate annealing → finish cold rolling → finish annealing. Nos. 11 to 18 and 49 to 54 adopted the process described above, omitting the hot-rolled material annealing. No. 55 was subjected to an aging treatment process, while Nos. 56 and 57 were subjected to a solution treatment and aging treatment process. The sheet products after finish annealing (except No. 57, which was a sheet product after finish cold rolling) were used as test materials and subjected to the following investigation.

[0057] (Measurement of the number density of large and medium-sized precipitate particles) The number densities of large and medium-sized precipitate particles were measured according to the "Method for determining the number density of large and medium-sized precipitate particles" mentioned above. The FE-SEM used was a JEOL JSM-7200F. Each measurement area was a rectangular area of ​​300 μm × 400 μm. The measurement of the particle's major axis and the counting of the number of particles with major axes within a specified range were performed using the image analysis software ImageJ (National Institutes of Health (NIH), Version 1.52a) as follows:

[0058] To set the analysis conditions for the above software, select Analyze, then Set Scale, and on the "Set Scale" screen that appears, measure the number of pixels for the scale bar length of the captured FE-SEM image and enter it in "Distance in pixels." Next, enter the length of the scale bar (μm) in "Known distance," set the Pixel aspect ratio to 1.0, and the Unit of length to μm, so that the size of the precipitates can be recognized in the software. Then, on the "Resize Image Canvas" screen, set the Width to 1280 pixels, the Height to 950 pixels, and the Position to Top-Center, and display the FE-SEM image portion excluding the scale bar. After setting this scale and deleting the scale bar display, the "Threshold" screen was displayed by selecting Image, Adjust, and Threshold in that order, and the brightness was inverted so that the lowest brightness pixel of all pixels had a brightness of 255 and the highest brightness pixel had a brightness of 0. The threshold was then set to a value that would bring the proportion of pixels below that value to all pixels closest to 5%, and the areas where precipitate particles existed were binarized and identified. After that, on the "Analyze Particles" screen of the same software, the area of ​​one independent precipitate region was determined to be 0.0019 μm 2 To exclude particles with a major axis smaller than this, the size was set to "0.0019-Infinity." Furthermore, particle analysis was performed with the circularity set to 0.00-1.00 and the Fit Ellipse item checked on the "Set Measurements" screen, and the number of large precipitate particles with a major axis (displayed as the "Major" item name) in the field of view was counted, including those with a major axis in the range of 0.15 μm to 2.00 μm, and those with a medium diameter in the range of 0.05 μm to less than 0.15 μm.

[0059] (Measurement of the number density of small precipitate particles) The number density of small diameter precipitate particles was measured according to the above-mentioned "Method for determining the number density of small diameter precipitate particles." The FE-SEM used was a JSM-7200F manufactured by JEOL Ltd. Here, a rectangular measurement area of ​​0.8 μm × 1.2 μm was set for a secondary electron image taken at 100,000 magnification, and the number of all particles with a major axis of 0.005 μm or more and less than 0.050 μm present in that measurement area was counted, and the number was rounded to two significant digits to 1 mm. 2 The density was converted to number density per particle.

[0060] (EBSD measurement) A cross section perpendicular to the rolling direction of a sample taken from the test material was polished using a cross-section polisher (JEOL Ltd., IB-19530CP) at an accelerating voltage of 4 kV to prepare the sample surface for EBSD (electron backscatter diffraction) measurement. The sample surface was observed using a field emission scanning electron microscope (FE-SEM) (JEOL Ltd., JSM-7200F) at an accelerating voltage of 15 kV and a magnification of 5000x. Crystal orientation data were collected using the EBSD method with a step size of 0.05 μm using an EBSD instrument (Oxford Instruments, Symmetry) installed in the FE-SEM. The KAM value and average grain size were measured based on the crystal orientation data measured in two non-overlapping measurement areas according to the "Calculation of KAM value" and "Calculation of average grain size" methods described above. The EBSD data analysis software used was OIM-Analysis 7.3.1 (TSL Solutions, Inc.).

[0061] (tensile strength) Tensile test pieces (JIS No. 5) were taken from each test material in the direction perpendicular to the rolling direction, and tensile tests were conducted in accordance with JIS Z2241 with n = 3 tests to measure the tensile strength. The average value of n = 3 was used as the performance value for the test material.

[0062] (conductivity) The electrical conductivity of each test material was measured using the double bridge, average cross-sectional area method in accordance with JIS H0505. Considering the electrical conductivity required for current-carrying parts such as small connectors, materials with a conductivity of 45% IACS or higher were judged to pass.

[0063] (bending workability) In accordance with the Japan Copper and Brass Association technical standard JCBA T307:2007, a 90°W bending test was performed on the blank wall to determine the ratio (MBR / t) of the minimum bending radius (MBR) at which cracks did not occur to the sheet thickness (t). The test specimen size was 30 mm in the direction perpendicular to the rolling direction on the sheet surface and 10 mm in the rolling direction (width of the test specimen). The presence or absence of cracks on the bent surface was determined according to JCBA T307:2007. For samples judged to have "large wrinkles" in the appearance observation of the bent surface, a specimen was cut perpendicular to the bending axis at the deepest wrinkle, and the polished cross section was observed under an optical microscope to check for cracks extending into the sheet thickness. If no cracks were found, the specimen was judged to have "no cracks observed." Considering the intended use of the material of the present invention, a specimen with an MBR / t of 2.0 or less in this test was judged to pass.

[0064] (Fatigue properties) Test pieces 3 mm wide and 20 mm long, with the width direction in the rolling direction (LD) and the length direction transverse to the rolling direction (TD), were cut out from the test material, and a reversed fatigue test was carried out using the cantilever resonance method with a fatigue testing device (Nippon Technoplus Co., Ltd., RF-RT) at a load stress of 300 MPa. The change in the resonance frequency was monitored during the test, and the number of cycles at which the resonance frequency reached 98% of the initial value was taken as the fatigue limit of the test piece. This procedure was carried out on five test pieces made from one test material, and the average value of their fatigue limits was adopted as the fatigue limit of the test material. When this fatigue limit was 10 5 cycle or more was judged to be acceptable. The results are shown in Tables 1 to 4.

[0065] [Table 1]

[0066] [Table 2]

[0067] [Table 3]

[0068] [Table 4]

[0069] The copper alloy sheets of the examples, which had chemical compositions, number densities of large-diameter precipitate particles, KAM values, and tensile strengths within the ranges specified by the present invention, were able to achieve both good bending workability and good fatigue properties, and also had good electrical conductivity.

[0070] In contrast, the comparative examples Nos. 41 and 49 had poor electrical conductivity because the Ni and Si contents were too high. In Nos. 42 and 50, the Ni and Si contents were insufficient, which resulted in a low density of small precipitate particles and low strength. Furthermore, the low strength resulted in insufficient improvement in fatigue properties. In No. 43, the holding temperature during hot-rolled annealing was too high, which led to recrystallization and a large average grain size. Furthermore, the precipitates redissolved, resulting in a low density of small-diameter precipitate particles. This resulted in low strength and electrical conductivity, and the fatigue properties were also poorly improved. In No. 44, the holding temperature during hot-rolled annealing was low, resulting in the formation of a large amount of small-diameter precipitate particles, resulting in a hard structure. In addition, recrystallization was insufficient, resulting in large lattice distortion and a high KAM value. As a result, bending workability was poor.

[0071] In Nos. 45 and 51, the holding temperature during intermediate annealing was too high, which led to recrystallization and a larger average grain size. Furthermore, the precipitates redissolved, resulting in a lower number density of small-diameter precipitate particles. Since there was no process for sufficient small-diameter precipitate particles to form after intermediate annealing, the final sheet material had low strength and poor electrical conductivity. However, No. 45 had many large-diameter precipitate particles, so its fatigue properties were good. On the other hand, No. 51 did not have as many large-diameter precipitate particles as No. 45, and its strength was slightly lower than No. 45, so the improvement in fatigue properties was insufficient. In Nos. 46 and 52, the holding temperature during intermediate annealing was low, so few particles grew to the size of large-diameter precipitate particles, resulting in a hard structure with a high number density of small-diameter precipitate particles. Furthermore, insufficient recrystallization resulted in large lattice distortion and a high KAM value. As a result, bending workability was poor. However, fatigue properties were good due to the increased strength. In Nos. 47 and 53, the reduction ratio in the finish cold rolling was too high, resulting in a large amount of processing strain and an increase in the KAM value. As a result, bending workability was poor. In Nos. 48 and 54, the reduction ratio in the finish cold rolling was low, which resulted in insufficient introduction of processing strain and low strength. In addition, these samples did not contain as many large-diameter precipitate particles as No. 45, so the improvement in fatigue properties was also insufficient.

[0072] Nos. 55, 56, and 57 are examples of alloys manufactured using a conventional manufacturing process that involves aging treatment. Of these, No. 55 omitted solution treatment, resulting in a high level of residual lattice strain, resulting in a high KAM value and poor bending workability. Nos. 56 and 57 underwent solution treatment, resulting in a good balance of strength, electrical conductivity, and bending workability, but at a high manufacturing cost. Regarding fatigue properties, the heat treatment after solution treatment did not sufficiently form large-diameter precipitate particles, resulting in a low number density, leaving further improvement desirable.

Claims

1. In mass%, the alloy consists of Ni: 2.00 to 5.10%, Si: 0.30 to 1.20%, Ag: 0 to 0.30%, Al: 0 to 1.00%, B: 0 to 0.20%, Co: 0 to 1.0%, Cr: 0 to 0.50%, Fe: 0 to 1.00%, Mg: 0 to 0.50%, Mn: 0 to 1.00%, Nb: 0 to 1.00%, P: 0 to 0.20%, S: 0 to 0.20%, Sn: 0 to 1.00%, Ti: 0 to 0.50%, Zn: 0 to 1.00%, Zr: 0 to 0.30%, rare earth elements: 0 to 3.00% in total, with the balance being Cu and unavoidable impurities; The steel has a chemical composition in which the total content of Ag, Al, B, Co, Cr, Fe, Mg, Mn, Nb, P, S, Sn, Ti, Zn, Zr, and rare earth elements is 4.00% or less, and in measurements of a measurement area provided on a cross section perpendicular to the rolling direction by EBSD (electron backscatter diffraction) with a step size of 0.05 μm, the KAM value is 3.00° or less when boundaries with a crystal orientation difference of 5° or more are considered to be grain boundaries, and the number density of large-diameter precipitate particles with a major axis of 0.15 μm or more and 2.00 μm or less on a cross section parallel to the rolling surface is 5.0 × 10 ４ pieces / mm ２ The copper alloy sheet material has a tensile strength of 500 MPa or more in a direction perpendicular to the rolling direction.

2. The number density of small-diameter precipitate particles having a major axis of 0.005 μm or more and less than 0.050 μm in a cross section parallel to the rolled surface is 5.0 × 10 ６ pieces / mm ２ The copper alloy sheet material according to claim 1 .

3. 2. The copper alloy sheet according to claim 1, wherein, in the measurement by EBSD with a step size of 0.05 μm, an average crystal grain size measured by an Area Fraction method when a boundary having a crystal orientation difference of 5° or more is considered to be a crystal grain boundary is 4.00 μm or less.

4. In a cross section parallel to the rolling surface, the number density of the large diameter precipitate particles is a (pieces / mm ２ ), and the number density of medium-sized precipitate particles with a major axis of 0.05 μm or more and less than 0.15 μm is defined as b (particles / mm ２ 2. The copper alloy sheet according to claim 1, wherein the following formula (1) is satisfied: 0.01≦a / b≦0.30 ... (1)

5. In the measurement by EBSD with a step size of 0.05 μm, the KAM value is 1.50° or less when a boundary with a crystal orientation difference of 5° or more is considered to be a grain boundary, and the average crystal grain size is 1.60 μm or more and 3.60 μm or less by the Area Fraction method, and the number density of the large diameter precipitate particles is 7.0 × 10 in a cross section parallel to the rolled surface. ４ pieces / mm ２ and the number density of small-diameter precipitate particles having a major axis of 0.005 μm or more and less than 0.050 μm is 10.0×10 ６ pieces / mm ２ The copper alloy sheet material according to claim 1 .

6. 2. The copper alloy sheet material according to claim 1, having an electrical conductivity of 45% IACS or more.

7. 2. The copper alloy sheet material according to claim 1, wherein a ratio MBR / t of a minimum bending radius MBR at which cracking does not occur to a sheet thickness t in a 90° W bending test at B.W. in accordance with Japan Copper and Brass Association Technical Standard JCBA T307:2007 is 2.0 or less.

8. In a reversed-swing fatigue test using a cantilever resonance method with a test piece whose longitudinal direction is perpendicular to the rolling direction, the fatigue limit at a load stress of 300 MPa was 1.0 x 10 ５ The copper alloy sheet material according to claim 1, wherein the temperature is 1000 to 2000 sintered bodies.

9. A method for producing a copper alloy sheet material according to claim 1, When an unannealed hot-rolled material having the above chemical composition that has not been subjected to heat treatment after hot rolling is subjected to hot-rolled material annealing, intermediate cold rolling, intermediate annealing, finish cold rolling, and finish annealing in the above order to obtain a plate product, The hot-rolled material is annealed at a temperature of 400°C or higher and 650°C or lower for 5 hours or higher and 20 hours or lower, The intermediate cold rolling is performed under the condition of a rolling ratio of 25% or more, The intermediate annealing is carried out under conditions of holding the temperature at 400°C or higher and 650°C or lower for 5 hours or higher and 20 hours or lower, The finish cold rolling is carried out under the condition of a rolling ratio of 39% or more and 95% or less, The finish annealing is performed under the condition of heating to a temperature of 300°C or more and 500°C or less. Manufacturing method of copper alloy sheet material.

10. A method for producing a copper alloy sheet material according to claim 1, When an unannealed hot-rolled material or an unannealed cold-rolled material having the above-mentioned chemical composition that has not been subjected to heat treatment after hot rolling is subjected to intermediate annealing, finish cold rolling, and finish annealing in the above-mentioned order to obtain a plate product, The intermediate annealing is carried out under conditions of holding the temperature at 400°C or higher and 650°C or lower for 5 hours or higher and 20 hours or lower, The finish cold rolling is carried out under the condition of a rolling ratio of 34% or more and 90% or less, The finish annealing is performed under the condition of heating to a temperature of 300°C or more and 500°C or less. Manufacturing method of copper alloy sheet material.

11. The method for producing a copper alloy sheet according to claim 9 or 10, wherein the temperature is not increased to a temperature range exceeding 650°C in steps subsequent to the hot rolling.

12. A current-carrying part using the copper alloy sheet material according to any one of claims 1 to 8 as a material.

13. A heat dissipation part using the copper alloy sheet material according to any one of claims 1 to 8 as a material.

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