Cu-ti-al-based copper alloy sheet material, electronic device component, current-carrying component, and heat dissipation component

Abstract

To provide a Cu-Ti based copper alloy sheet material combining satisfactory strength, bending workability, fatigue properties and press blanking properties.SOLUTION: 1.00 to 5.00% of Ti and 0.50 to 3.80% of Al, and as necessary, 3.00% or less of one or more of Ag, B, Co, Cr, Fe, Hf, Mg, Mn, Mo, Nb, Ni, P, S, Si, Sn, Ta, V, Zn, and Zr, and 3.00% of rare earth elements in total, with the balance being Cu and inevitable impurities, in an observation plane parallel to a sheet surface, an average grain size by an intercept method is 2 to 20 μ m, a number concentration of Cu-Ti-based coarse precipitate particles a having a major diameter of 1.0 μm or more is 7.0 * 104 particles / mm2 or less, a number concentration of Cu-Ti-Al-based precipitate particles b having a major diameter of 0.3 μm or more is 7.0 * 104 particles / mm2 or more, and a tensile strength in a rolled direction is 850 to 1165MPa.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a Cu-Ti-Al based copper alloy sheet material having improved fatigue properties and press-punching properties, and to electronic equipment parts, current-carrying parts and heat-dissipating parts using the sheet material as a material. [Background technology]

[0002] Cu-Ti copper alloys (copper-titanium alloys) have a high level of strength among various copper alloys and good stress relaxation resistance, making them widely used in current-carrying spring parts and heat-dissipating parts such as connectors, relays, and switches. These electronic components are often manufactured through press working. In recent years, with the increasing sophistication of mobile devices such as smartphones and automotive electronic devices, there has been an increasing demand for miniaturization and narrower pitches in the electronic components used in them. To meet this demand, it is important for the copper alloy materials used as component materials to not only achieve both strength and bending workability, but also to improve fatigue properties and press-punching properties.

[0003] Patent Documents 1 and 2 disclose techniques for improving the press-punchability of Cu-Ti alloys by adding elements such as Fe and performing solution treatment twice, but do not describe a method for simultaneously improving fatigue properties.

[0004] Meanwhile, there has been a growing need in recent years for weight reduction in electronic device components. In response to this demand, the present applicant developed a technology in which 0.5 mass % or more of Al is added to a Cu-Ti-based copper alloy to reduce its density (specific gravity), and a process of performing solution treatment twice is employed to maintain a good balance between strength and bending workability, and this technology is disclosed in Patent Document 3. In this specification, a Cu-Ti-based copper alloy to which Al is added to such an extent that it can exert a density-reducing effect is specifically referred to as a "Cu-Ti-Al-based copper alloy." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-249565 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-242881 [Patent Document 3] Japanese Patent Application Publication No. 2023-152264 Summary of the Invention [Problem to be solved by the invention]

[0006] The technology disclosed in the above Patent Document 3 has made it possible to obtain a Cu-Ti-based copper alloy sheet material that has both good strength and bending workability and also has the effect of reducing density. However, the technology of Patent Document 3 does not intend to improve fatigue properties or press-punching properties, and there is still room for further study.

[0007] An object of the present invention is to provide a technique for simultaneously improving fatigue properties and press-punchability while maintaining good strength and bending workability in a Cu-Ti-Al based copper alloy sheet material. [Means for solving the problem]

[0008] As a result of investigations, the inventors have found that in Cu-Ti-Al copper alloys, achieving a microstructural state in which Cu-Ti-Al precipitate particles with a major axis of 0.3 μm or more are sufficiently formed is extremely effective in simultaneously improving fatigue properties and press-punchability. It has been confirmed that such a microstructural state can be achieved by a single solution treatment process in which the alloy is heated to a high temperature. When the metallographic structure of the copper alloy sheet material disclosed in Patent Document 3 was examined, the presence of the above-mentioned Cu-Ti-Al precipitate particles was confirmed to some extent, but it became clear that the amount of formation was insufficient to improve press-punchability. Based on these findings, the present specification discloses the following invention.

[0009] [1]In mass%, Ti: 1.00~5.00%, Al: 0.50~3.80%, Ag: 0~0.30%, B: 0~0.30%, Co: 0~1.00%, Cr: 0~1.00%, Fe: 0~1.00%, Hf: 0 ~1.00%, Mg:0~1.00%, Mn:0~2.00%, Mo:0~1.00%, Nb:0~0.50%, Ni:0~1.00%, P:0~0.50%, S:0~0.30%, Si:0~0.50%, S The alloy has a chemical composition consisting of n: 0-2.00%, Ta: 0-1.00%, V: 0-1.00%, Zn: 0-3.00%, Zr: 0-1.00%, rare earth elements: 0-3.00% in total, and the balance being Cu and unavoidable impurities, wherein the total content of Ag, B, Co, Cr, Fe, Hf, Mg, Mn, Mo, Nb, Ni, P, S, Si, Sn, Ta, V, Zn, and Zr among the elements is 3.00% or less, the average crystal grain size measured in a plane observed parallel to the sheet surface by a cutting method in accordance with JIS H0501-1986 is 2-20 μm, and the number density of Cu-Ti-based coarse precipitate particles a having a major axis of 1.0 μm or more in a plane observed parallel to the sheet surface is 7.0 × 10 4 pieces / mm 2 Hereinafter, the number density of Cu-Ti-Al-based precipitate particles b with a major axis of 0.3 μm or more is 7.0 × 10 4 pieces / mm 2 The copper alloy sheet material has a tensile strength in the rolling direction of 850 to 1165 MPa. [2] The copper alloy sheet material according to the above [1], having a nanoindentation index Q of 2.00 GPa or less as determined by the method according to the following (X): (X) In the region from the 1 / 4 position to the 3 / 4 position in the thickness direction of a cross section parallel to the rolling direction and the thickness direction, measurement points are set on a grid of points spaced 4 μm apart in the rolling direction and 4 μm apart in the thickness direction. At each measurement point, a Berkovich indenter is used to measure the nanoindentation hardness (GPa) under the conditions of loading up to a maximum load of 2 mN for 10 seconds, holding for 5 seconds, and unloading for 10 seconds. In the ranking of all measurement values, the arithmetic mean measurement value calculated excluding the measurement data corresponding to the top 10% and the bottom 10% of the total number of measurements is defined as A (GPa), and the arithmetic mean measurement value of only the measurement data corresponding to the bottom 10% of the total number of measurements is defined as B (GPa). The nanoindentation index Q (GPa) is determined by the following formula (1). Nanoindentation index Q = AB … (1) However, when the thickness of the copper alloy sheet material is t (μm), the number of rows of the measurement points in the rolling direction is i, and the number of rows in the thickness direction is j, the measurement points are set so that i is the largest integer that satisfies the following formula (2) and the total number of measurement points i × j satisfies the following formula (3). 4i≦t / 2 …(2) 100≦i×j≦150 …(3) [3] In a pulsating tensile fatigue test in the rolling direction under a load stress of 600 MPa and a frequency of 50 Hz, the number of cycles until fracture occurred was 1.0 × 10 5 The copper alloy sheet material according to [1] or [2] above, wherein the temperature is 1000 K or more. [4] The number density of the Cu-Ti-Al-based precipitate particles b having a major axis of 0.3 μm or more is 1.1 × 10 5 pieces / mm 2 Over 4.0 x 10 5 pieces / mm 2 The copper alloy sheet material according to any one of the above [1] to [3], which is: [5] The copper alloy sheet material according to any one of the above [1] to [4], which has an electrical conductivity of 7.5% IACS or more. [6] The copper alloy sheet material according to any one of the above [1] to [5], wherein the ratio MBR / t of the minimum bending radius MBR at which cracking does not occur to the sheet thickness t in a BW W-bend test according to the Japan Copper and Brass Association technical standard JCBA T307:2007 is 2.00 or less. [7] The copper alloy sheet material according to any one of the above [1] to [6], wherein the Al content in the chemical composition is 0.85 mass % or more. [8] An electronic device part using the copper alloy sheet material according to any one of [1] to [7] above as a material. [9] An electrical component using the copper alloy sheet material according to any one of [1] to [7] above as a material.

[10] A heat dissipation component using the copper alloy sheet material according to any one of [1] to [7] above as a material.

[0010] The copper alloy sheets [1] to [7] above can be produced by, for example, the following method

[11] or

[12] .

[11] Holding the intermediate product sheet having the above chemical composition at 770 to 910 °C for 20 to 600 seconds, a solution treatment, Holding the sheet obtained by the solution treatment at 320 to 480 °C for 5 to 20 hours, an aging treatment, Performing cold rolling with a rolling reduction of 10 to 50% on the sheet obtained by the aging treatment, a final cold rolling, Holding the sheet obtained by the final cold rolling at 400 to 500 °C for 30 to 180 seconds, a final heat treatment, A method for manufacturing a copper alloy sheet, comprising the steps of:

[12] Holding the intermediate product sheet having the above chemical composition at 770 to 910 °C for 20 to 600 seconds, a solution treatment, Performing cold rolling with a rolling reduction of 50% or less on the sheet obtained by the solution treatment, an intermediate cold rolling, Holding the sheet obtained by the intermediate cold rolling at 320 to 480 °C for 5 to 20 hours, an aging treatment, Performing cold rolling with a rolling reduction of 10 to 50% on the sheet obtained by the aging treatment, a final cold rolling, Holding the sheet obtained by the final cold rolling at 400 to 五00 °C for 30 to 1870 seconds, a final heat treatment, A method for manufacturing a copper alloy sheet, comprising the steps of:

[0011] 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. "Sheet" means a sheet-like metal material formed by utilizing the malleability of a metal. 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". "Sheet surface" is a surface perpendicular to the sheet thickness direction of the sheet. "Sheet surface" may also be called "rolling surface".

Advantages of the Invention

[0012] According to the present invention, in a Cu-Ti-Al based copper alloy sheet material, a novel method utilizing the formation of Al-containing precipitates has been developed, which has enabled the fatigue properties and press-punching properties to be simultaneously improved while maintaining good strength and bending workability. [Brief explanation of the drawings]

[0013] [Figure 1] 10 is an SEM image of an observation surface parallel to the sheet surface of the copper alloy sheet material obtained in Comparative Example 45. [Figure 2] 1 is an SEM image of an observation surface parallel to the sheet surface of the copper alloy sheet material obtained in Example 1. [Figure 3] 3 is a TEM image of an extraction replica film prepared on a cross section parallel to the plate surface of the copper alloy sheet material obtained in Example 1. [Figure 4] FIG. 10 is a cross-sectional view schematically showing the shape of a cut edge formed by press-punching a metal plate. [Figure 5] FIG. 2 is a diagram showing a schematic diagram of the shape of a test piece used in a fatigue test. DETAILED DESCRIPTION OF THE INVENTION

[0014] [Chemical composition] Hereinafter, "%" regarding alloy components means "% by mass" unless otherwise specified. Titanium (Ti) is an element that contributes to the formation of a Ti modulated structure by spinodal decomposition and the formation of fine second-phase particles by precipitation, thereby increasing the strength of the Cu-Ti-Al-based copper alloy of the present invention. It also contributes to improving stress relaxation resistance and reducing density (specific gravity). Here, alloys with a Ti content of 1.00% or more are considered. From the perspective of precipitation strengthening, the Ti content is preferably 1.50% or more, and even more preferably 3.00% or more. While an increased Ti content is advantageous for improving strength, excessive Ti content can reduce hot workability and cold workability, as well as bending workability. Therefore, the Ti content is limited to 5.00% or less. It may also be controlled to 4.90% or less, or 4.20% or less.

[0015] It has been found that Al (aluminum) serves as an Al supply source for generating Cu-Ti-Al-based precipitates by applying the manufacturing method described below, contributing to the simultaneous improvement of fatigue properties and press-punchability. Furthermore, Al is effective in suppressing the formation of coarse Cu-Ti-based precipitates, which also contributes to the simultaneous improvement of fatigue properties and press-punchability. Furthermore, Al is also effective in reducing the specific gravity of copper alloy sheets. To fully utilize these effects, an Al content of 0.50% or more is ensured. From the perspective of increasing Cu-Ti-Al-based precipitates and further improving press-punchability, an Al content of 0.70% or more is more effective, and an Al content of 0.85% or more is even more effective. However, since an excessive Al content reduces electrical conductivity, the Al content is set to 3.80% or less. An Al content of 3.00% or less is more preferable.

[0016] Ag (silver), B (boron), Co (cobalt), Cr (chromium), Fe (iron), Hf (hafnium), Mg (magnesium), Mn (manganese), Mo (molybdenum), Nb (niobium), Ni (nickel), P (phosphorus), S (sulfur), Si (silicon), Sn (tin), Ta (tantalum), V (vanadium), Zn (zinc), Zr (zirconium), and rare earth elements are optional elements. One or more of these elements can be added as needed. For example, Ni, Co, Fe, and Nb form intermetallic compounds with Ti, contributing to improved strength. Furthermore, these intermetallic compounds suppress grain coarsening, enabling solution treatment at higher temperatures during the production of copper alloy sheet, which is advantageous for fully dissolving Ti. Suppressing grain coarsening also has an advantage in terms of fatigue properties. Fe, in particular, is useful for improving strength and fatigue properties. Ag, Mo, Sn, and Ta have solid solution strengthening and stress relaxation resistance enhancing effects. Zn improves solderability and strength, as well as castability. Mg improves stress relaxation resistance and desulfurization. Si can form compounds with Ti, contributing to pinning during recrystallization in the production of copper alloy sheet, and is effective in preventing grain coarsening. Cr and Zr are effective in dispersion strengthening and suppressing grain coarsening. Mn and V easily form high-melting point compounds with S and other elements, and B and P have the effect of refining the cast structure, each of which can contribute to improving hot workability. Hf has the effect of reducing the solid solubility limit of Ti, thereby increasing the amount of precipitates formed during aging and improving electrical conductivity. Rare earth elements (REM) are Sc (scandium), Y (yttrium), and the lanthanoid elements (excluding Pm (promethium)) in Group 3 of the periodic table. The inclusion of rare earth elements is effective in refining crystal grains and dispersing precipitates. Misch metal (a mixture of rare earth elements) may be used as a supply source of rare earth elements.

[0017] The contents of the above optional elements can be set within the following ranges depending on the application and required properties: Ag: 0 to 0.30%, B: 0 to 0.30%, Co: 0 to 1.00%, Cr: 0 to 1.00%, Fe: 0 to 1.00%, Hf: 0 to 1.00%, Mg: 0 to 1.00%, Mn: 0 to 2.00%, Mo: 0 to 1.00%, Nb: 0 to 0.50%, Ni: 0 to 1.00%, P: 0 to 0.50%, S: 0 to 0.30%, Si: 0 to 0.50%, Sn: 0 to 2.00%, Ta: 0 to 1.00%, V: 0 to 1.00%, Zn: 0 to 3.00%, Zr: 0 to 1.00%, and rare earth elements: 0 to 3.00% in total. The rare earth elements may include, for example, one or more selected from La (lanthanum): 2.00% or less, Ce (cerium): 1.80% or less, Pr (praseodymium): 0.30% or less, Nd (neodymium): 0.80% or less, Sm (samarium): 2.50% or less, and Y (yttrium): 2.50% or less, with the total rare earth element content being 3.00% or less.

[0018] More preferred contents of each optional element include Ag: 0 to 0.20%, B: 0 to 0.20%, Co: 0 to 0.50%, Cr: 0 to 0.50%, Fe: 0 to 0.50%, Hf: 0 to 0.50%, Mg: 0 to 0.50%, Mn: 0 to 1.80%, Mo: 0 to 0.90%, Nb: 0 to 0.30%, Ni: 0 to 0.50%, P: 0 to 0.45%, S: 0 to 0.25%, Si: 0 to 0.20%, Sn: 0 to 0.60%, Ta: 0 to 0.50%, V: 0 to 0.50%, Zn: 0 to 2.00%, Zr: 0 to 0.50%, and rare earth elements: 0 to 0.80% in total. In this case, the content range of the rare earth elements can be, for example, a range including one or more selected from La: 0.50% or less, Ce: 0.50% or less, Pr: 0.15% or less, Nd: 0.50% or less, Sm: 0.50% or less, and Y: 0.50% or less, with the total content of the rare earth elements being 0.80% or less.

[0019] Furthermore, when emphasis is placed on economic efficiency and manufacturability, more preferred contents of each optional element can be, for example, in the ranges of Ag: 0 to 0.15%, B: 0 to 0.15%, Co: 0 to 0.15%, Cr: 0 to 0.15%, Fe: 0 to 0.15%, Hf: 0 to 0.25%, Mg: 0 to 0.25%, Mn: 0 to 0.75%, Mo: 0 to 0.75%, Nb: 0 to 0.05%, Ni: 0 to 0.40%, P: 0 to 0.30%, S: 0 to 0.16%, Si: 0 to 0.06%, Sn: 0 to 0.35%, Ta: 0 to 0.25%, V: 0 to 0.08%, Zn: 0 to 1.00%, Zr: 0 to 0.15%, and rare earth elements: 0 to 0.55% in total. In this case, the content range of the rare earth elements can be controlled to a range including, for example, one or more selected from La: 0.25% or less, Ce: 0.25% or less, Pr: 0.03% or less, Nd: 0.08% or less, Sm: 0.40% or less, and Y: 0.30% or less, with the total content of the rare earth elements being 0.55% or less.

[0020] Of the above optional elements, the total content of Ag, B, Co, Cr, Fe, Hf, Mg, Mn, Mo, Nb, Ni, P, S, Si, Sn, Ta, V, Zn, and Zr is set to 3.00% or less (including 0%). The upper limit of the total content of these optional elements is preferably set to 2.00% or less, and may be controlled to 1.20% or less, or 0.80% or less.

[0021] Elements other than those mentioned above are also permitted to be contained to the extent that they do not impair the objectives of the present invention (combining good strength, bending workability, fatigue properties, and press-punching properties). Specifically, the total content of elements other than Ti, Al, Ag, B, Co, Cr, Fe, Hf, Mg, Mn, Mo, Nb, Ni, P, S, Si, Sn, Ta, V, Zn, Zr, rare earth elements, and Cu (copper) (hereinafter sometimes referred to as "unspecified elements") may be controlled to 0.50% or less (including 0%), or may be controlled to 0.10% or less (including 0%). The contents of the elements specified in the present invention and 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.

[0022] (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).

[0023] The chemical composition of the copper alloy sheet material according to the present invention can also be specified as follows. In mass %, Ti: 1.00~5.00%, Al: 0.50~3.80%, Ag: 0~0.30%, B: 0~0.30%, Co: 0~1.00%, Cr: 0~1.00%, Fe: 0~1.00%, Hf :0~1.00%, Mg:0~1.00%, Mn:0~2.00%, Mo:0~1.00%, Nb:0~0.50%, Ni:0~1.00%, P:0~0.50%, S:0~0.30%, Si:0~ Chemical composition: 0.50%, Sn: 0-2.00%, Ta: 0-1.00%, V: 0-1.00%, Zn: 0-3.00%, Zr: 0-1.00%, rare earth elements: 0-3.00% in total, Ti, Al, Ag, B, Co, Cr, Fe, Hf, Mg, Mn, Mo, Nb, Ni, P, S, Si, Sn, Ta, V, Zn, Zr, rare earth elements, total of elements other than Cu (non-specified elements): 0.50% or less, balance Cu In this case, the contents of Ti and Al and the contents of the optional elements may be set within the more limited ranges described above, and the total content of non-specified elements may be limited to 0.10% or less.

[0024] [Average grain size] In Cu-Ti-Al-based copper alloy sheets having the above-described chemical composition, good fatigue properties are obtained when the average grain size measured on an observation surface parallel to the sheet surface by a cutting method conforming to JIS H0501-1986 is 2 to 20 μm. The average grain size is preferably 10 μm or less, and more preferably 5 μm or less. In a structural state where the average grain size is less than 2 μm, unrecrystallized grains may be present. From the viewpoint of maintaining stable and good bending workability, it is advantageous for the average grain size to be 2 μm or more. The cutting method specified in JIS H0501-1986 stipulates that "the average cutting length (mm) is used for the measurement," but since the grain size targeted in this invention is very small compared to this standard unit of measurement, measurements conforming to the method of the standard are performed using a higher magnification observation field to determine the average grain size in μm units.

[0025] [Precipitate] In this invention, simultaneous improvements in fatigue properties and press-punchability are achieved by controlling the metal structure to minimize the presence of coarse Cu-Ti precipitate particles with major axes of 1.0 μm or larger while ensuring a sufficient presence of Cu-Ti-Al precipitate particles with major axes of 0.3 μm or larger. These precipitates can be identified and their number density measured by observing a carbon replica film (hereinafter referred to as an "extraction replica film") extracted from the surface of a sheet material sample using a transmission electron microscope (TEM) and then examining the Cu, Al, and Ti contents of the particles using an energy dispersive X-ray spectroscopy (EDS) analyzer attached to the TEM. Hereinafter, this type of analytical electron microscope will be abbreviated as "TEM-EDS," and observations and measurements using a TEM-EDS will be referred to as "TEM-EDS observations."

[0026] (Identification of precipitates) Cu-Ti-based precipitates and Cu-Ti-Al-based precipitates are distinguished as follows based on quantitative analysis data obtained by TEM-EDS observation of precipitate particles extracted in extraction replica films. Cu-Ti precipitates: Cu≧40 atomic %, Ti≧20 atomic %, Al<10 atomic % Cu-Ti-Al precipitates: Cu≧50 atomic %, Ti≧20 atomic %, Al≧10 atomic % The major axis of a precipitate particle is the diameter (μm) of the smallest circumscribed circle surrounding the particle in a TEM image of the extraction replica film. For convenience, in this specification, Cu-Ti precipitate particles with a major axis of 1.0 μm or more are referred to as "Cu-Ti coarse precipitate particles a," and Cu-Ti-Al precipitate particles with a major axis of 0.3 μm or more are referred to as "Cu-Ti-Al precipitate particles b," and are distinguished by the symbols a and b.

[0027] (Count of precipitates) The number density of precipitate particles a and b was measured by randomly selecting one or multiple non-overlapping observation areas (total area 500 μm) on the TEM image of the extracted replica membrane. 2 The particle size is determined by counting the number of particles present in the observation area (above). For particles that are partially cut off by the boundary of the observation area, the boundary that cuts the particle is considered to be part of the particle's outline, and the particle portion that exists within the observation area is counted if it meets the conditions for precipitate particles a and b. The extraction replica membrane can be prepared by the following procedure.

[0028] [Example of the procedure for preparing an extraction replica membrane] (Step 1) The surface of a copper alloy sheet sample, which has been buffed, is electropolished using an electropolishing solution made by mixing distilled water, phosphoric acid, ethanol, and 2-propanol in a volume ratio of 10:5:5:1, at a solution temperature of 20°C, a voltage of 15 V, and a time of 20 seconds.Then, the sample is rinsed with running water for 30 seconds and dried with warm air to obtain an electropolished sample surface. (Step 2) After dropping methyl acetate onto the surface of the sample, place an acetyl cellulose (AC) film on top and let it dry. (Step 3) The AC film is peeled off from the sample surface. This extracts the precipitate particles that were on the sample surface onto the AC film side, and an AC film with precipitate particles attached to its surface is obtained. (Step 4) A carbon vapor deposition film with a thickness of approximately 10 nm is formed on the entire surface of the peeled AC film on the side where the precipitate particles are attached. (Step 5) The carbon-deposited side of the AC film is placed on the surface of a glass plate with paraffin between, to obtain a laminate consisting of a glass plate, a paraffin layer, a carbon film, and an AC film. In this laminate, the carbon film is simply placed on the paraffin layer and can be easily separated together with the AC film. (Step 6) The laminate is immersed in a methyl acetate solution to dissolve the AC film, leaving a carbon film (extraction replica film) carrying precipitate particles suspended in the solution. (Step 7) The carbon film (extraction replica film) is transferred to a new methyl acetate solution and washed, and then the carbon film is collected by scooping it up with a Mo support mesh for TEM observation and dried.

[0029] [Number density of Cu-Ti coarse precipitate particles a] The Cu-Ti coarse precipitate particles a are mainly present within crystal grains, and as their number increases, they adversely affect fatigue properties and press-punchability. As a result of investigation, it was found that in the Cu-Ti-Al alloy sheet material of the present invention, the number density of the Cu-Ti coarse precipitate particles a with a major axis of 1.0 μm or more is 7.0 × 10 4 pieces / mm 2 Limited to 6.5 x 10 4 pieces / mm 2 The size of the resulting Cu-Ti based coarse precipitate particles a is usually 10.0 μm or less in terms of major axis.

[0030] 1 shows an example of an SEM image (secondary electron image) of the electrolytically polished surface of the copper alloy sheet material obtained in Comparative Example 45. Coarse Cu-Ti precipitate particles a are observed at the location indicated by the arrow a.

[0031] [Number density of Cu-Ti-Al precipitate particles b] It was found that Cu-Ti-Al based precipitate particles b are mainly present at the grain boundaries and contribute to the simultaneous improvement of fatigue properties and press-punching properties. As a result of the investigation, it was found that in the Cu-Ti-Al based copper alloy sheet material of the present invention, Cu-Ti-Al based precipitate particles b with a major axis of 0.3 μm or more are present in an amount of 7.0 × 10 4 pieces / mm2 From the viewpoint of press punching properties, the number density of precipitate particles b is 9.0 × 10 4 pieces / mm 2 More preferably, it is 1.1 × 10 5 pieces / mm 2 It is particularly preferable that the ratio is 1.1×10 or more. 5 pieces / mm 2 When the number density is higher than this, the burr height, which is an index of press-punching property described later, is 2.0 μm or less. In addition, the precipitate particle b is usually 4.0 × 10 5 pieces / mm 2 It is sufficient that the precipitate particles b are present within the following range. Conventionally, precipitate particles b containing Al are not present in sheets of ordinary Cu-Ti-based copper alloys (so-called titanium copper). Furthermore, even in known Cu-Ti-Al-based copper alloy sheets, a structural state in which this type of precipitate particles b is present in sufficient amounts has not been obtained. A predetermined amount of precipitate particles b can be formed by the manufacturing process described below, in which the solution treatment (high-temperature heat treatment) is limited to one run. The size of the Cu-Ti-Al-based precipitate particles b thus generated is usually 5.0 μm or less in major axis.

[0032] 2 shows an example of an SEM image (secondary electron image) of the surface of a sample obtained by electrolytically polishing the copper alloy sheet material obtained in Example 1 described later. Numerous Cu-Ti-Al-based precipitate particles b, as indicated by arrows b, are observed. Figure 3 shows a TEM image of the extraction replica film prepared by the above-mentioned procedure for the copper alloy sheet material obtained in Example 1 described later. TEM-EDS observation of this extraction replica film confirmed that the particles indicated by the arrows in Figure 2 were Cu-Ti-Al-based precipitate particles b.

[0033] [Tensile strength] The tensile strength in the rolling direction (LD) of the copper alloy sheet material of the present invention is preferably 850 MPa or more, more preferably 870 MPa or more. It is also possible to adjust the tensile strength in the rolling direction to a strength level of 1000 MPa or more. However, if the tensile strength is made too high, bending workability may be impaired. The present invention is directed to a sheet material having a tensile strength in the rolling direction of 1165 MPa or less.

[0034] [Nanoindentation index Q] The nanoindentation index Q determined by the method according to (X) above is an index that indicates the degree of strength reduction in local strength variations within a cross section near the center of the sheet thickness. The smaller the nanoindentation index Q, the smaller the degree of local strength reduction in the structure, which is particularly advantageous for improving fatigue properties. According to the inventors' studies, the nanoindentation index Q is preferably 2.00 GPa or less, more preferably 1.50 GPa or less, and even more preferably 1.00 GPa or less.

[0035] The "region from the 1 / 4 position to the 3 / 4 position in the thickness direction" specified in (X) above refers to the region where the distance from one surface of the plate is between t / 4 and 3t / 4, where t is the plate thickness. Regarding the number of rows of measurement points i in the rolling direction and the number of rows j in the thickness direction, for example, in the case of a plate material with a plate thickness of 60 μm, i is 7 points, which is the maximum integer that satisfies the above formula (2), and j can be set in the range of 15 to 21 points using the above formula (3).

[0036] [Fatigue properties] Fatigue properties can be evaluated by conducting a pulsating tensile fatigue test in which a test piece is subjected to repeated stress in the rolling direction at a load stress of 600 MPa (minimum load is 1 / 10 of the maximum load, uncompressed) and a frequency of 50 Hz (sine wave), and by measuring the number of repetitions N until fracture occurs. In this case, as shown in Figure 5, the test piece is 60 mm long, with the longitudinal direction in the rolling direction, a 9 mm width at the gripping section, a 2 mm length at the parallel section, a 1 mm width at the parallel section, and a 1 mm radius at the transition point from the parallel section to the gripping section (a total of four shoulders). The test piece is prepared by cutting it out of the copper alloy sheet material used as the test material using laser processing and then removing burrs using a router. In the fatigue test, the gripping section (bottom) in Figure 5 is fixed, and the gripping section (top) is repeatedly pulled. The number of repetitions N until fracture under these fatigue test conditions is 1.0 x 10 5 It is preferable that the fatigue characteristic is 4.5×10 5 It is more preferable that the number of cycles N until fracture under the fatigue test conditions is 4.5 × 10 5 In order to stably achieve excellent fatigue properties of ≥ 1000 cycles, the Al content must be 3.10% or less, the strength must be 900 MPa or more, and the number density of precipitate particles b must be 9.0 × 10 4 pieces / mm 2 The number of cycles N until fracture under the fatigue test conditions is usually 1.0 × 10 8 The range will be less than times.

[0037] [conductivity] Considering the use of the Cu-Ti-Al-based copper alloy sheet material, the electrical conductivity is preferably 7.5% IACS or more, more preferably 8.0% IACS or more, and even more preferably 10.0% IACS or more. The upper limit of the electrical conductivity is not particularly limited, but it is usually adjusted to be within the range of 20.0% IACS or less.

[0038] [Bending workability] Bending is often required when processing electrical components, etc. Considering the applications of Cu-Ti-Al alloy sheet materials, if they have bending workability in which the ratio of the minimum bending radius (MBR) at which cracks do not occur to the sheet thickness (t) (MBR / t) is 2.00 or less in a BW W-bend test according to the Japan Copper and Brass Association technical standard JCBA T307:2007, high reliability can be achieved when processing many electrical components and heat-dissipating components. MBR / t at BW is more preferably 1.0 or less, and even more preferably 0.70 or less. It is also possible to obtain a BW MBR / t of 0.0 (no cracks occurring in tight bending). BW (Bad Way) means that the bending axis is parallel to the rolling direction.

[0039] 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 confirmed that it is possible to evaluate the bending workability of Cu-Ti-Al-based 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.

[0040] [Press punching ability] Figure 4 shows a schematic diagram of the shape of the cut edge of the remaining material (the material that was in contact with the die) formed by press-punching a metal sheet. Burrs (also called burrs) generally occur on the cut edge. Materials that are less likely to produce burrs when punched with an appropriate clearance are easier to maintain after punching, which is advantageous for improving part productivity. For Cu-Ti-based copper alloy sheets, when aiming for a good balance between strength and bending workability, there is no established method for consistently reducing the amount of burrs generated on the cut edge of press-punching, which has been a problem. Here, press-punching properties are evaluated based on the burr height shown in Figure 4. The Cu-Ti-Al-based copper alloy sheet of the present invention stably maintains good press-punching properties in addition to strength, bending workability, and fatigue properties. Specifically, it exhibits good press-punching properties, with the burr height on the press-punched surface measured by the method described below being 3.0 μm or less, or even 2.0 μm or less. Note that the burr height measured by the method described below is usually 0.4 μm or more.

[0041] [Manufacturing method] The copper alloy sheet material described above can be manufactured, for example, by the following manufacturing process. Melting and casting → Slab heating → Hot working → Rough cold rolling → Solution treatment → (Intermediate cold rolling) → Aging treatment → Finishing cold rolling → Final annealing Although not described in the above steps, facing is performed as needed after hot working, and pickling, polishing, or further degreasing is performed as needed after each heat treatment. The intermediate cold rolling can be omitted. Each of the above steps will be explained below.

[0042] [Melting and Casting] A cast slab having the chemical composition specified in the present invention may be produced using a crucible furnace, etc. To prevent oxidation of Ti and Al, it is preferable to carry out the process in an inert gas atmosphere or a vacuum melting furnace.

[0043] [Slab heating] The slab can be heated before hot working by, for example, holding it at 900 to 1000°C for 0.5 to 5 hours.

[0044] [Hot processing, rough cold rolling] The method of hot working is not particularly limited. Usually, hot rolling or hot forging is adopted. In the case of hot rolling, the total hot rolling reduction ratio may be, for example, 60 to 99%. After the hot working is completed, it is preferable to rapidly cool the material by water cooling or the like. Then, cold rolling is performed. In this specification, the cold rolling at this stage is called "rough cold rolling". The rolling reduction ratio in rough cold rolling can be, for example, 50 to 99%. In this way, an intermediate product sheet material to be subjected to solution treatment can be obtained. Here, the rolling ratio is expressed by the following formula (4) (the same applies to each of the following steps). Rolling ratio (%) = 100 × (t0 - t1) / t0…(4) t0: thickness of plate material to be rolled (mm) t1: Plate thickness after the final rolling pass (mm)

[0045] [Solution treatment] The intermediate product sheet material is subjected to a solution treatment. This solution treatment utilizes the strain introduced by hot working and rough cold rolling to recrystallize the material, fully dissolving the coarse grain boundary reaction precipitates and granular precipitates formed after casting or during hot working. Conventional manufacturing methods for Cu-Ti-Al copper alloy sheets include intermediate cold rolling and a second solution treatment in addition to the solution treatment, which refines the grains through recrystallization. However, improving the press-punchability of such a manufacturing process is difficult. The inventors therefore conducted extensive research. As a result, they discovered that a single solution treatment in Cu-Ti-Al copper alloys results in the formation of many Cu-Ti-Al precipitate particles (b) during subsequent aging treatment, and that these precipitate particles (b) are extremely effective in improving press-punchability. They also found that precipitate particles (b) are effective in improving fatigue properties. It has been confirmed that it is difficult to consistently ensure the production of sufficient Cu-Ti-Al-based precipitate particles b during aging treatment when high-temperature recrystallization heat treatment is performed multiple times before aging treatment. Therefore, the high-temperature recrystallization heat treatment performed after hot working is limited to this single solution treatment. This solution treatment can be performed by holding the intermediate product sheet material at 770 to 910°C for 20 to 600 seconds. If the solution treatment temperature is higher than 910°C, the crystal grains are likely to coarsen due to recrystallization, which can adversely affect fatigue properties.

[0046] [Intermediate cold rolling] After solution treatment, the material can be cold-rolled as needed to reduce the thickness. Cold rolling at this stage is called intermediate cold rolling. If the reduction ratio in intermediate cold rolling is too large, the strength will be excessively high, which may impair bending workability. The reduction ratio in intermediate cold rolling is limited to 50% or less. When intermediate cold rolling is used, it is effective to ensure a reduction ratio of 5% or more from the perspective of reducing the thickness.

[0047] [Aging treatment] Aging treatment is performed on materials that have undergone solution treatment or intermediate cold rolling. The aging treatment can be performed by holding the material at 320 to 480°C for 5 to 20 hours. As described above, this aging treatment sufficiently generates Cu-Ti-Al-based precipitate particles b with a major axis of 0.3 μm or more, which are effective in improving press-punching properties. If the holding temperature for the aging treatment is too high, the generated precipitate particles may coalesce, making it difficult to keep the number density of precipitate particles b within the specified range. Furthermore, localized hardness fluctuations may occur, increasing the nanoindentation index Q and deteriorating fatigue properties. On the other hand, if the holding temperature for the aging treatment is too low, insufficient precipitation may result in insufficient strength improvement. Furthermore, the amount of precipitate particles b generated may be insufficient, resulting in insufficient improvements in fatigue properties and press-punching properties.

[0048] [Finishing cold rolling] After the aging treatment, the sheet is subjected to finish cold rolling at a rolling reduction of 10 to 50% to adjust to the final target thickness. If the rolling reduction in this process is too high, the sheet may become hard and hinder bending workability. On the other hand, if the rolling reduction is too low, sufficient strength may not be obtained. The Ti content has a significant effect on improving strength, but the rolling reduction in this cold rolling process can also be used to control the strength to a predetermined level. The final thickness of the Cu-Ti-Al-based copper alloy sheet material can be, for example, in the range of 0.02 to 0.50 mm.

[0049] [Final heat treatment] After the finish cold rolling, the material is subjected to a final heat treatment at 400-500°C for 30-180 seconds. This adjusts the strain distribution within the structure and improves bending workability.

[0050] [Electronic components, current-carrying components, heat-dissipating components] The copper alloy sheet material of the present invention as described above has good strength, bending workability, electrical conductivity, fatigue properties, and press-punching properties, and also has a reduced density (specific gravity). Therefore, electronic device parts, current-carrying parts, and heat-dissipating parts formed by processes including pressing and bending using this sheet material as a material meet the demands for high functionality in recent years for mobile terminals and electronic devices for automobiles. [Example]

[0051] Copper alloys having the chemical compositions shown in Tables 1 to 5 were melted and cast slabs (50 mm thick) were obtained. In No. 14, 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 5 using the method described in the above section "Example of a method for quantifying alloying elements."

[0052] The obtained slabs were heated at the temperatures and times shown in Tables 1 to 5, then hot rolled to the thicknesses shown in Tables 1 to 5, and water-cooled. After hot rolling, the surface oxide layer was removed (face milled) by mechanical polishing, and each hot-rolled material was subjected to rough cold rolling at the rolling ratios shown in Tables 1 to 5 to obtain intermediate product sheets for solution treatment.

[0053] The intermediate product sheets were subjected to solution treatment, followed by aging treatment, finish cold rolling, and final heat treatment in that order. Examples 8, 9, 11, and 12 and Comparative Examples 42, 47, 52, and 54 were subjected to intermediate cold rolling between the solution treatment and the aging treatment. Comparative Example 54 was further subjected to a second solution treatment and a second intermediate rolling between the intermediate cold rolling and the aging treatment. The conditions for each of these steps and the final sheet thickness are shown in Tables 1 to 5. The plate material that had undergone the final heat treatment was used as a test material for the following investigation.

[0054] (Average grain size) The test specimen surface was polished and then electropolished under the conditions described in "Example of Extraction Replica Film Preparation Procedure (Procedure 1)" above. The resulting surface was observed at 2000x magnification using an optical microscope (Keyence VHX-5000 Digital Microscope) to capture an image. A 100 μm × 100 μm square measurement area was randomly selected within the image. Three lines parallel to the rolling direction were drawn within the measurement area. The number of grain boundaries cut by each line was counted using a cutting method in accordance with JIS H0501-1986 to calculate the average grain size. This procedure was performed on 10 randomly selected, non-overlapping fields. The arithmetic mean (rounded to the nearest μm) of the average grain size values ​​obtained in each field was used as the average grain size for the sheet. Sheets with an average grain size between 2 and 20 μm were deemed acceptable.

[0055] (Number density of precipitate particles a and b) Extraction replica membranes were prepared according to steps 1 to 7 shown in the above-mentioned "Example of the procedure for preparing extraction replica membranes." For the electrolytic polishing in step 1, an electrolytic polishing device (Electropolisher Power Supply, Electropolisher Cell Module) manufactured by BUEHLER was used. The obtained extraction replica membranes were observed by TEM-EDS (TOPCON EM-002B 200 kV), and randomly set 500 μm 2 The Cu-Ti and Cu-Ti-Al precipitates present in the observation area were identified based on the EDS quantitative analysis values ​​of Cu, Ti, and Al, using the criteria described in "Identification of Precipitates" above. For each identified precipitate, the number of Cu-Ti precipitate particles a with a major axis of 1.0 μm or more and Cu-Ti-Al precipitate particles b with a major axis of 0.3 μm or more were counted under the conditions described in "Counting of Precipitates" above, and these counts were divided into particles with an area of ​​1 mm. 2 By converting it into the number of pieces, the number density (pieces / mm 2 ) was calculated.

[0056] The major axis of the precipitate particles (the diameter of the smallest circumscribed circle surrounding the particle) was measured using Image J (National Institutes of Health (NIH), Version 1.52a) image analysis software. Analysis using this software was performed under the following conditions: Select Analyze, then Set Scale. On the "Set Scale" screen, measure the number of pixels along the scale bar of the captured TEM image and enter the value in the "Distance in pixels" field. Next, enter the length of the scale bar (μm) in the "Known distance" field, set the "Pixel aspect ratio" to 1.0, and set the "Unit of length" to μm, so that the software can identify the size of the precipitates. Then, on the "Resize Image Canvas" screen, set the Width to 2048 pixels, the Height to 1800 pixels, and the Position to Top-Center to display the TEM image excluding the scale bar. After setting this scale and deleting the scale bar display, select Image, Adjust, and Threshold. On the "Threshold" screen, invert the brightness so that the lowest and highest brightness pixels are 255 and 0, respectively. Then, set the threshold value so that the percentage of pixels below that value is closest to 3% of the total pixels. This binarized and identified the areas where precipitate particles existed. After that, on the "Analyze Particles" screen of the software, the area of ​​one independent precipitate region was found to be 0.00006 μm 2 To exclude particles with a major axis of 1.0 μm or larger, the size was set to "0.00006-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 density a of precipitate particles with a major axis (displayed as the "Major" item name) of 1.0 μm or larger and the number density b of precipitate particles with a major axis of 0.3 μm or larger were determined for that field of view.

[0057] (nanoindentation hardness) To enable measurement of cross sections parallel to the rolling direction and thickness direction, samples cut from the test material were embedded in resin and prepared by mechanical polishing and colloidal silica mirror polishing. The nanoindentation hardness (GPa) of this test surface was measured using the method specified in (X) above to determine the values ​​of A and B, and the nanoindentation index Q shown in equation (1) was calculated. The measurement device used was an ENT-5YM manufactured by Elionix. The number of rolling rows (i) and the number of rows (j) in the thickness direction of the measurement points, arranged in a grid pattern with 4 μm intervals, were set to i = 10 and j = 10 for the test material with a thickness of 0.080 mm, and i = 7 and j = 15 for the test material with a thickness of 0.060 mm, so as to satisfy the requirements of equations (2) and (3).

[0058] (tensile strength) Tensile test pieces (JIS No. 5) were taken from each test material in the rolling direction (LD), and tensile tests were performed in accordance with JIS Z2241 with the number of tests (n = 3) to measure the tensile strength. The average value of n = 3 was used as the performance value for the test material.

[0059] (conductivity) The electrical conductivity of each test material was measured by the double bridge average cross-sectional area method in accordance with JIS H0505. Test materials with a conductivity of 7.5% IACS or higher were judged to pass.

[0060] (MBR / t for 90°W bend) The ratio (MBR / t) of the minimum bending radius (MBR) at which cracks did not occur to the sheet thickness (t) was determined using a W-bend test in accordance with the Japan Copper and Brass Association technical standard JCBA T307:2007. The test specimen size was 30 mm in the transverse direction and 10 mm in the rolling direction. Three bending tests were conducted at each bending radius, with the bending radius gradually varied. The minimum bending radius at which cracks were not observed on the bent surface in all three specimens was defined as the MBR for that specimen. The presence or absence of cracks on the bent surface was determined according to JCBA T307:2007. For samples that were 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. The polished cross section was examined using an optical microscope to check for cracks extending into the sheet thickness. If no cracks were observed, the specimen was judged to have "no cracks observed." A specimen with an MBR / t of 2.00 or less was judged to pass.

[0061] (Fatigue test) A tensile fatigue test was conducted with a load stress of 600 MPa using the method described in the "Fatigue Properties" section above, and the number of cycles N until fracture occurred was determined. A Shimadzu Servo Pulser (EHF-EM100k1-020-1A) tensile fatigue tester was used. Five tests were conducted, and the average value expressed to two significant figures was used as the performance of the test material. When the performance of the number of cycles N was 1.0 x 10 5 Those with a value of 100 times or more were judged to be acceptable.

[0062] (burr height on press punched surface) A rectangular plate measuring 5 mm x 6 mm with a corner radius of 0.4 mm was punched out of the test material with a clearance of 5% so that the long sides of the rectangle were parallel to the rolling direction. The maximum burr height (the maximum burr height shown in Figure 4 at the two opposing cut edges) of the remaining blank (the material that had been in contact with the die) was measured using a laser microscope. This measurement was performed on three punched sections, and the arithmetic mean of the maximum burr heights at each punched section was calculated. This was used as the burr height (μm) for the test material. A burr height of 3.00 μm or less was deemed acceptable. The results are shown in Tables 1 to 5.

[0063] [Table 1]

[0064] [Table 2]

[0065] [Table 3]

[0066] [Table 4]

[0067] [Table 5]

[0068] The copper alloy sheets of the examples, in which the chemical composition, average crystal grain size, number density of the Cu-Ti coarse precipitate particles a and the Cu-Ti-Al precipitate particles b, and tensile strength were controlled within the ranges of the present invention, had high levels of strength as well as bending workability, fatigue properties, and press-punching properties, and also had good electrical conductivity. In all of the examples, the major axis of the Cu-Ti-Al based precipitate particles b was 5 μm or less.

[0069] In contrast, the comparative examples gave the following results. In No. 41, the Ti content was too high, resulting in an excessively high strength level and insufficient bending workability. In No. 42, the Ti content was insufficient, resulting in a low strength level and insufficient fatigue properties. In No. 43, the Al content was insufficient, resulting in an insufficient amount of precipitate particles b formed and insufficient suppression of the formation of coarse precipitate particles a, resulting in insufficient improvement in fatigue properties and press-punchability. No. 44 is a Cu-Ti-based copper alloy (so-called titanium copper) containing no Al. When the manufacturing process disclosed herein was applied to this alloy, the Al effect of suppressing the formation of coarse precipitate particles a was not exhibited, resulting in a metal structure with a large amount of coarse precipitate particles a, resulting in poor fatigue properties. Furthermore, the absence of precipitate particles b prevented any improvement in press-punching properties.

[0070] In No. 45, the solution treatment temperature was too high, which resulted in coarsening of the crystal grains and insufficient improvement in fatigue properties. In No. 46, the solution treatment temperature was too low, resulting in insufficient solute atom solid solution and insufficient strengthening by aging treatment, resulting in a low strength level. Furthermore, the coarse second phase in the cast structure was not solidified sufficiently, resulting in an increase in the amount of coarse precipitate particles A, but the amount of precipitate particles B was also large, so the fatigue properties were within the acceptable level. In No. 47, the reduction ratio of the intermediate cold rolling was too high, resulting in an excessively high strength level and poor bending workability. In No. 48, the aging temperature was too high, which led to the coalescence of precipitate particles and a decrease in the number density of precipitate particles b. It is also thought that this resulted in a structure with locally weak areas, resulting in a high indentation index Q. As a result, improvements in fatigue properties and press-punchability were insufficient. In No. 49, the aging temperature was too low, resulting in insufficient formation of fine precipitates, which are effective in improving strength, and thus low strength. Furthermore, the amount of precipitate particles b formed was insufficient, resulting in poor fatigue properties and press-punchability. Furthermore, the amount of Ti and Al dissolved in solid solution was high, resulting in low electrical conductivity.

[0071] In No. 50, the reduction ratio in the finish cold rolling was too high, resulting in an excessively high strength level and poor bending workability. In No. 51, the reduction ratio in the finish cold rolling was too low, resulting in little processing strain being introduced and a low strength level. In No. 52, the aging temperature was too low, resulting in an insufficient amount of precipitate particles b, and the fatigue properties and press-punchability were poor. Compared to the above No. 49, in this example, intermediate cold rolling was performed, which introduced strain, resulting in higher strength, and the low Al content also resulted in high electrical conductivity. In No. 53, the reduction ratio in the finish cold rolling was very high, so the strength level was higher than that of No. 1, but the bending workability was reduced. For No. 54, the conventional manufacturing process of Cu-Ti-Al-based copper alloy sheet material disclosed in Patent Document 3 was adopted. That is, before the aging treatment, a set of solution treatment and intermediate cold rolling was performed twice, and finish cold rolling and final heat treatment were omitted. In this case, the amount of precipitate particles b generated was small, and improvement in press-punchability could not be achieved. Furthermore, since the strength was sufficiently high and the nanoindentation index Q was low, it is considered that the structure was in a state with almost no locally weak parts, and the fatigue properties were acceptable.

Claims

1. In mass%, Ti: 1.00-5.00%, Al: 0.50-3.80%, Ag: 0-0.30%, B: 0-0.30%, Co: 0-1.00%, Cr: 0-1.00%, Fe: 0-1.00%, Hf: 0-1 .00%, Mg: 0-1.00%, Mn: 0-2.00%, Mo: 0-1.00%, Nb: 0-0.50%, Ni: 0-1.00%, P: 0-0.50%, S: 0-0.30%, Si: 0-0.50%, Sn : 0 to 2.00%, Ta: 0 to 1.00%, V: 0 to 1.00%, Zn: 0 to 3.00%, Zr: 0 to 1.00%, rare earth elements: 0 to 3.00% in total, the balance being Cu and unavoidable impurities, wherein the total content of Ag, B, Co, Cr, Fe, Hf, Mg, Mn, Mo, Nb, Ni, P, S, Si, Sn, Ta, V, Zn, and Zr among the elements is 3.00% or less, the average crystal grain size in a plane observed parallel to the plate surface is 2 to 20 μm according to a cutting method in accordance with JIS H0501-1986, and the number density of Cu-Ti-based coarse precipitate particles a having a major axis of 1.0 μm or more in a plane observed parallel to the plate surface is 7.0 × 10 ４ pieces / mm ２ Hereinafter, the number density of Cu-Ti-Al based precipitate particles b having a major axis of 0.3 μm or more is 7.0 × 10 ４ pieces / mm ２ The copper alloy sheet material has a tensile strength of 850 to 1165 MPa in the rolling direction.

2. The copper alloy sheet according to claim 1, wherein the nanoindentation index Q determined by the method according to the following (X) is 2.00 GPa or less. (X) In a region from the 1 / 4 position to the 3 / 4 position in the thickness direction of a cross section parallel to the rolling direction and the thickness direction, measurement points are set on lattice points spaced 4 μm apart in the rolling direction and 4 μm apart in the thickness direction. At each measurement point, a Berkovich indenter is used to measure the nanoindentation hardness (GPa) under the conditions of loading up to a maximum load of 2 mN for 10 seconds, holding for 5 seconds, and unloading for 10 seconds. In the ranking of all measurement values, the arithmetic mean measurement value calculated excluding the measurement data corresponding to the top 10% and the measurement data corresponding to the bottom 10% of the total number of measurements is defined as A (GPa), and the arithmetic mean measurement value of only the measurement data corresponding to the bottom 10% of the total number of measurements is defined as B (GPa). The nanoindentation index Q (GPa) is determined by the following formula (1): Nanoindentation index Q = A - B ... (1) However, when the thickness of the copper alloy sheet material is t (μm), the number of rows of the measurement points in the rolling direction is i, and the number of rows in the thickness direction is j, the measurement points are set so that i is the largest integer that satisfies the following formula (2) and the total number of measurement points i × j satisfies the following formula (3). 4i≦t / 2 ... (2) 100≦i×j≦150 ... (3)

3. In a pulsating tensile fatigue test in the rolling direction under a load stress of 600 MPa and a frequency of 50 Hz, the number of repetitions N until fracture occurred was 1.0 x 10 ５ The copper alloy sheet material according to claim 1, wherein the temperature is 1000°C or more.

4. The number density of the Cu-Ti-Al-based precipitate particles b having a major axis of 0.3 μm or more is 1.1 × 10 ５ pieces / mm ２ Above 4.0 x 10 ５ pieces / mm ２ The copper alloy sheet material according to claim 1, wherein:

5. 2. The copper alloy sheet material according to claim 1, having an electrical conductivity of 7.5% IACS or more.

6. 2. The copper alloy sheet 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 B.W. W-bend test according to Japan Copper and Brass Association Technical Standard JCBA T307:2007 is 2.00 or less.

7. The copper alloy sheet material according to claim 1, wherein the chemical composition contains 0.85 mass% or more of Al.

8. An electronic device part using the copper alloy sheet material according to any one of claims 1 to 7 as a material.

9. A current-carrying part using the copper alloy sheet material according to any one of claims 1 to 7 as a material.

10. A heat dissipation part using the copper alloy sheet material according to any one of claims 1 to 7 as a material.

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