Cu-Ti-Al-BASED COPPER ALLOY SHEET MATERIAL, ELECTRONIC APPARATUS COMPONENT, CURRENT-CARRYING COMPONENT, AND HEAT DISSIPATION COMPONENT

Abstract

[Problem] To provide a Cu-Ti-based copper alloy sheet material having excellent strength, bending workability, fatigue characteristics, and press-punching properties. [Solution] A copper alloy sheet material containing, in mass%, 1.00-5.00% of Ti and 0.50-3.80% of Al, and additionally containing, 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 a total of 3.00% of rare earth elements, the balance comprising Cu and inevitable impurities. The copper alloy sheet material is such that: in an observation plane parallel to the sheet surface, the number density of Cu-Ti-based coarse precipitate particles (a) having an average crystal grain size obtained through a cutting method of 2-20 μm and a major axis of 1.0 μm or greater is 7.0 × 104 per mm2 or lower, and the number density of Cu-Ti-Al-based precipitate particles (b) having a major axis of 0.3 μm or greater is 7.0 × 104 per mm 2 or higher; and the tensile strength in the rolling direction is 850-1165 MPa.

Description

Cu-Ti-Al copper alloy sheet materials, electronic equipment parts, current-carrying parts and heat-dissipating parts

[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.

[0002] Among various copper alloys, Cu-Ti-based copper alloys (copper-titanium alloys) have a high level of strength 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 device parts 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 device parts used therein. To meet this demand, it has become 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] On the other hand, there has been a growing need in recent years for weight reduction of electronic device components. In order to meet 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 the 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 was 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 particularly referred to as a "Cu-Ti-Al-based copper alloy."

[0005] JP 2006-249565 A JP 2009-242881 A JP 2023-152264 A

[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 a density reduction effect. 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-punching properties while maintaining good strength and bending workability in Cu-Ti-Al based copper alloy sheet materials.

[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 metal structure of the copper alloy sheet material disclosed in Patent Document 3 was examined, it was found that the presence of the above-mentioned Cu-Ti-Al precipitate particles was confirmed to some extent, but the amount of the particles formed was insufficient to improve press-punchability. Based on these findings, the present specification discloses the following invention.

[0009] [1] In mass%, Ti: 1.00 to 5.00%, Al: 0.50 to 3.80%, 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 ~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 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, and the balance 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 by a cutting method in accordance with JIS H0501-1986 in a plane observed parallel to the plate surface is 2 to 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 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[2] The copper alloy sheet 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 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 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) where t (μm) is the thickness of the copper alloy sheet, i is the number of rows of the measurement points in the rolling direction, and j is the number of rows in the thickness direction, and 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 at a load stress of 600 MPa and a frequency of 50 Hz, the number of repetitions N until fracture occurs is 1.0×10 ５ [4] The copper alloy sheet material according to the above [1] or [2], wherein 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[5] The copper alloy sheet according to any one of [1] to [3] above, having an electrical conductivity of 7.5% IACS or more. [6] The copper alloy sheet according to any one of [1] to [4] above, having a 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 Japan Copper and Brass Association Technical Standard JCBA T307:2007, of 2.00 or less. [7] The copper alloy sheet according to any one of [1] to [6] above, having an Al content of 0.85 mass% or more in the chemical composition. [8] An electronic device part made from the copper alloy sheet according to any one of [1] to [7] above. [9] An electric component made from the copper alloy sheet according to any one of [1] to [7] above.

[10] A heat dissipation part made from the copper alloy sheet according to any one of [1] to [7] above.

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

[11] or

[12] .

[11] A method for producing a copper alloy sheet, comprising: a solution treatment in which an intermediate product sheet having the above chemical composition is held at 770 to 910°C for 20 to 600 seconds; an aging treatment in which the sheet obtained by the solution treatment is held at 320 to 480°C for 5 to 20 hours; a finish cold rolling in which the sheet obtained by the aging treatment is cold rolled at a rolling ratio of 10 to 50%; and a final heat treatment in which the sheet obtained by the finish cold rolling is held at 400 to 500°C for 30 to 180 seconds.

[12] A method for manufacturing a copper alloy sheet material, comprising: a solution treatment in which an intermediate product sheet material having the above-described chemical composition is held at 770 to 910°C for 20 to 600 seconds; an intermediate cold rolling in which the sheet material obtained by the solution treatment is cold rolled at a rolling reduction of 50% or less; an aging treatment in which the sheet material obtained by the intermediate cold rolling is held at 320 to 480°C for 5 to 20 hours; a finish cold rolling in which the sheet material obtained by the aging treatment is cold rolled at a rolling reduction of 10 to 50%; and a final heat treatment in which the sheet material obtained by the finish cold rolling is held at 400 to 500°C for 30 to 180 seconds.

[0011] In this specification, the notation "n1 to n2" indicating a numerical range means "greater than or equal to n1 and less than or equal to n2." Here, n1 and n2 are numerical values ​​that satisfy n1 < n2. "Plate" refers to a sheet-like metal material formed by utilizing the malleability of metal. Thin sheet-like metal materials are sometimes called "foils," and such "foils" are also included in the "plate" referred to here. Long sheet-like metal materials wound into a coil are also included in the "plate". In this specification, the thickness of a sheet-like metal material is referred to as the "plate thickness." "Plate surface" refers to the surface perpendicular to the thickness direction of the plate. "Plate surface" is also sometimes called "rolled surface."

[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 able to simultaneously improve fatigue properties and press-punching properties while maintaining good strength and bending workability.

[0013] 1. SEM image of an observation surface parallel to the sheet surface of the copper alloy sheet obtained in Comparative Example 45. 2. SEM image of an observation surface parallel to the sheet surface of the copper alloy sheet obtained in Example 1. 3. TEM image of an extraction replica film prepared for a cross section parallel to the sheet surface of the copper alloy sheet obtained in Example 1. 4. A cross-sectional view schematically showing the shape of a cut edge formed by press-punching a metal plate. 5. A diagram schematically showing the shape of a test piece used in a fatigue test.

[0014] [Chemical Composition] Hereinafter, "%" in relation to alloy components means "mass %" unless otherwise specified. Ti (titanium) is an element that contributes to increasing the strength of the Cu-Ti-Al-based copper alloy of the present invention by forming a modulated structure of Ti through spinodal decomposition and by forming fine second-phase particles through precipitation. It also contributes to improving stress relaxation resistance and reducing density (specific gravity). Here, alloys containing 1.00% or more of Ti are targeted. 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 increase in 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 aluminum (Al) serves as an Al supply source for generating Cu-Ti-Al 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 precipitates, which also contributes to the simultaneous improvement of fatigue properties and press-punchability. Furthermore, Al is also effective in lowering 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 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 excessively high Al content reduces electrical conductivity, the Al content is limited 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, the intermetallic compounds of these elements suppress grain coarsening, enabling solution treatment at higher temperatures in the production of copper alloy sheet materials, which is advantageous for fully dissolving Ti. Suppressing grain coarsening is also advantageous in terms of fatigue properties. Fe, in particular, is useful for improving strength and fatigue properties. Ag, Mo, Sn, and Ta have the effect of solid solution strengthening and improving stress relaxation resistance. Zn not only improves solderability and strength, but is also effective in improving castability. Mg has the effect of improving stress relaxation resistance and desulfurization. Si can form compounds with Ti, contributing to pinning during recrystallization in the production of copper alloy sheet materials and effective in preventing coarsening of crystal grains. Cr and Zr are effective for dispersion strengthening and suppressing coarsening of crystal grains. Mn and V easily form high-melting point compounds with S and the like, and B and P have the effect of refining the cast structure, so each can contribute to improving hot workability. Hf has the effect of reducing the solid solubility limit of Ti, so it is effective in increasing the amount of precipitates generated during aging and improving electrical conductivity. The rare earth elements (REM) are Sc (scandium), Y (yttrium), and lanthanoid elements (excluding Pm (promethium)) of 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 the rare earth elements.

[0017] The contents of the above optional elements can be set within the range of 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%, rare earth elements: total 0 to 3.00%. 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 are 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: a total of 0 to 0.80%. 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 are, for example, 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 ability). 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 (for example, ONH-836 manufactured by LECO), H (hydrogen) is quantified using a hydrogen analyzer (for example, EMGA-921 manufactured by Horiba, Ltd.), C (carbon) and S (sulfur) are quantified using a carbon-sulfur analyzer (for example, CS844 type manufactured by LECO), elements of 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 (for example, 7900 manufactured by Agilent), and F (fluorine), Cl (chlorine), and Br (bromine) are quantified using a combustion-ion chromatography apparatus (for example, DIONEX ICS-1600 manufactured by Thermo Scientific).

[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 to 5.00%, Al: 0.50 to 3.80%, 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%. A chemical composition consisting of 0%, V: 0-1.00%, Zn: 0-3.00%, Zr: 0-1.00%, rare earth elements: 0-3.00%, 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 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 each of the optional elements may be set within the more limited ranges described above. The total content of non-specified elements may be limited to 0.10% or less.

[0024] [Average grain size] In Cu-Ti-Al copper alloy sheets having the above-described chemical composition, good fatigue properties are obtained when the average grain size measured in a plane 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, an average grain size of 2 μm or more is advantageous. The cutting method specified in JIS H0501-1986 stipulates that "the average cut length (mm) is used for display," but since the grain size targeted in this invention is very small compared to this standard display unit, measurements are performed in a higher magnification field of view conforming to the method of the standard to determine the average grain size in μm units.

[0025] [Precipitates] In the present 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 more while ensuring a sufficient presence of Cu-Ti-Al precipitate particles with major axes of 0.3 μm or more. 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 with 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) equipped on 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 identified as follows based on quantitative analysis data obtained by TEM-EDS observation of precipitate particles extracted in the extraction replica film: Cu-Ti-based precipitates: Cu≧40 atomic %, Ti≧20 atomic %, Al<10 atomic % Cu-Ti-Al-based precipitates: Cu≧50 atomic %, Ti≧20 atomic %, Al≧10 atomic % The major axis of a precipitate particle is defined as the diameter (μm) of the smallest circumscribed circle surrounding the particle in the TEM image of the extraction replica film. For convenience, in this specification, Cu-Ti based precipitate particles having a major axis of 1.0 μm or more are referred to as "Cu-Ti based coarse precipitate particles a," and Cu-Ti-Al based precipitate particles having a major axis of 0.3 μm or more are referred to as "Cu-Ti-Al based precipitate particles b," and are distinguished by the symbols a and b.

[0027] (Counting of precipitates) The number density of precipitate particles a and b was measured by counting one or more non-overlapping observation areas (total area 500 μm ) randomly placed on the TEM image of the extracted replica membrane. ２ The number of particles present in the observation area is determined by counting the number of particles present in the observation area (or 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 present in the observation area is counted if it meets the precipitate particle a and b requirements. Extraction replica films can be made using the following procedure.

[0028] [Example of Extraction Replica Film Fabrication Procedure] (Step 1) The surface of a copper alloy sheet sample, which had been buffed, was electropolished using an electropolishing solution consisting of 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. The sample was then rinsed with running water for 30 seconds and dried with warm air to obtain an electropolished sample surface. (Step 2) Methyl acetate was dripped onto the sample surface, followed by the placement of an acetyl cellulose (AC) film and drying. (Step 3) The AC film was peeled off from the sample surface. This extracted the precipitate particles present on the sample surface onto the AC film, yielding an AC film with precipitate particles attached to its surface. (Step 4) A carbon vapor deposition film approximately 10 nm thick was formed on the entire surface of the peeled AC film on the side where the precipitate particles were attached. (Step 5) The side of the AC film on which the carbon vapor deposition film has been formed is placed on the surface of a glass plate via paraffin, resulting in a laminate consisting of a glass plate, paraffin layer, carbon film, and AC film. In this laminate, the carbon film simply rests on the paraffin layer and is easily separated along with the AC film. (Step 6) The laminate is immersed in a methyl acetate solution to dissolve the AC film. This leaves the carbon film (extraction replica film) carrying the precipitate particles suspended in the liquid. (Step 7) The carbon film (extraction replica film) is transferred to a new methyl acetate solution and washed, after which the carbon film is scooped up and collected with a Mo support mesh for TEM observation and dried.

[0029] [Number Density of Cu-Ti Coarse Precipitate Particles a] Cu-Ti coarse precipitate particles a are mainly present within crystal grains, and when their number increases, they adversely affect fatigue properties and press-punching properties. As a result of investigation, it was found that in the Cu-Ti-Al copper alloy sheet material of the present invention, the number density of Cu-Ti coarse precipitate particles a having 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 coarse precipitate particles a is usually 10.0 μm or less in major axis.

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

[0031] [Number Density of Cu-Ti-Al Precipitate Particles b] It was found that Cu-Ti-Al precipitate particles b are mainly present at grain boundaries and contribute to the simultaneous improvement of fatigue properties and press-punching properties. As a result of investigation, it was found that in the Cu-Ti-Al copper alloy sheet material of the present invention, the number of Cu-Ti-Al precipitate particles b having a major axis of 0.3 μm or more was 7.0 × 10 ４ pieces / mm ２ 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 or more. 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 to be described later, is 2.0 μm or less. 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 a manufacturing process described below in which the solution treatment (high-temperature heat treatment) is limited to one execution. The size of the resulting Cu-Ti-Al-based precipitate particles b is usually 5.0 μm or less in major axis.

[0032] Figure 2 shows an example of an SEM image (secondary electron image) of a sample surface obtained by electropolishing the copper alloy sheet material obtained in Example 1 described below. Numerous Cu-Ti-Al-based precipitate particles b, as indicated by arrows b, are observed. Figure 3 shows an example of a TEM image of an extraction replica film prepared by the above-described procedure for the copper alloy sheet material obtained in Example 1 described below. TEM-EDS observation of this extraction replica film confirmed that the particles indicated by arrows in Figure 2 are 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 too high, bending workability may be impaired. The present invention targets sheet materials 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 can indicate the degree of strength reduction in local strength variations within a cross section near the center of the plate thickness. The smaller the nanoindentation index Q, the smaller the structure is evaluated to have a smaller degree of local strength reduction, which is particularly advantageous for improving fatigue properties. According to studies by the inventors, 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 means a region in which 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 as the maximum integer that satisfies the above formula (2), and j can be set in the range of 15 to 21 points according to the above formula (3).

[0036] [Fatigue Properties] Fatigue properties can be evaluated by performing 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 counting the number of cycles N until fracture occurs. In this case, as shown in Figure 5, the test piece has a longitudinal direction in the rolling direction, a total length of 60 mm, a gripping portion width of 9 mm, a parallel portion length of 2 mm, a parallel portion width of 1 mm, and a radius of the transition from the parallel portion to the gripping portion (a total of four shoulders) of 1 mm. The test piece is prepared by cutting the copper alloy sheet material as the test material by laser processing and then removing burrs by grinding with a router. In the fatigue test, the gripping portion (lower) in Figure 5 is fixed, and the gripping portion (upper) is repeatedly pulled. The number of cycles 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 realize excellent fatigue properties of 1000 cycles or more, the Al content is 3.10% or less, the strength is 900 MPa or more, and the number density of precipitate particles b is 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] [Electrical Conductivity] In consideration of the applications of Cu-Ti-Al based copper alloy sheets, 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 a range of 20.0% IACS or less.

[0038] [Bending workability] Bending is often required when fabricating current-carrying components, etc. Considering the applications of Cu-Ti-Al alloy sheets, 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 in accordance with the Japan Copper and Brass Association Technical Standard JCBA T307:2007, high reliability can be achieved when fabricating many current-carrying components and heat-dissipating components. BW MBR / t is 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 having 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 copper alloy sheets having a thickness of less than 0.1 mm by the W-bend test method described in the standard. Therefore, in the present invention, the B.W. W-bend test method shown in JCBA T307:2007 is extended to sheets having 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] [Punchability] 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 at 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 at the cut edge of press-punching, which has been a problem. Here, the press-punchability is 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-punchability in addition to strength, bending workability, and fatigue properties. Specifically, it exhibits good press-punchability, 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 steps: Melting / casting → heating of the cast slab → hot working → rough cold rolling → solution treatment → (intermediate cold rolling) → aging treatment → finish cold rolling → final annealing Although not described in the above steps, facing is performed as needed after the 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 described below.

[0042] [Melting and Casting] A cast 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 melting in an inert gas atmosphere or a vacuum melting furnace.

[0043] [Heating of Cast Slab] The heating of the cast slab before hot working can be carried out by, for example, holding it at 900 to 1000° C. for 0.5 to 5 hours.

[0044] [Hot working, 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 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 carried out. In this specification, cold rolling at this stage is called "rough cold rolling". The rolling reduction 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 reduction is expressed by the following formula (4) (the same applies to each of the following steps): Rolling reduction (%) = 100 × (t ０ -t １ ) / t ０ …(4) t ０ t: thickness of plate material to be rolled (mm) １ : Plate thickness (mm) of plate material after final rolling pass

[0045] [Solution Treatment] The intermediate product sheet material is subjected to solution treatment. This solution treatment utilizes the strain introduced by hot working and rough cold rolling to recrystallize, sufficiently 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 this solution treatment, which refines the grains through recrystallization. However, improving press-punchability in such a manufacturing process has been difficult. Therefore, the inventors conducted extensive research. As a result, they discovered that in Cu-Ti-Al copper alloys, a single solution treatment 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 ensure a stable and sufficient production of Cu-Ti-Al-based precipitate particles b during aging treatment when high-temperature heat treatment accompanied by recrystallization is performed multiple times before aging treatment. Therefore, the high-temperature heat treatment accompanied by recrystallization 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 become coarse due to recrystallization, which can adversely affect fatigue properties.

[0046] [Intermediate cold rolling] After the solution treatment, the material can be subjected to cold rolling 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 becomes 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 employed, it is effective to ensure a reduction ratio of 5% or more from the viewpoint 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 produces sufficient 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 the 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 produced may be insufficient, resulting in insufficient improvements in fatigue properties and press-punching properties.

[0048] [Finish Cold Rolling] After the aging treatment, finish cold rolling is performed at a rolling ratio of 10 to 50% to adjust to the final target plate thickness. If the rolling ratio in this process is too high, hardening may occur, hindering bending workability. On the other hand, if the rolling ratio is too low, sufficient strength may not be obtained. The Ti content has a significant effect on strength improvement, but the rolling ratio in this cold rolling process can also be used to control the strength to a predetermined level. The final plate thickness of the Cu-Ti-Al based copper alloy plate 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 in which it is held at 400 to 500°C for 30 to 180 seconds. This adjusts the strain distribution within the structure and improves bending workability.

[0050] [Electronic device components, current-carrying components, heat-dissipating components] The copper alloy sheet material of the present invention described above has good strength, bending workability, electrical conductivity, fatigue properties, and press-punching ability, and also has a reduced density (specific gravity). Therefore, electronic device components, current-carrying components, and heat-dissipating components 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.

[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 in a proportion of 0.30 mass% of the total amount of copper alloy raw material. 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 shown in Tables 1 to 5 using the method described in the above-mentioned "Example of a method for quantifying alloying elements."

[0052] The obtained cast pieces 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, among these, was 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 processes and the final sheet thickness are shown in Tables 1 to 5. The sheets that had undergone the final heat treatment were used as test materials for the following investigations.

[0054] (Average grain size) After polishing the plate surface of the test material, the observation surface obtained by electrolytic polishing under the conditions described in the above-mentioned "Example of the procedure for preparing an extraction replica film (Procedure 1)" was observed at a magnification of 2000 times using an optical microscope (Keyence Corporation digital microscope VHX-5000), and an observation image was obtained. A square measurement area of ​​100 μm x 100 μm was randomly set in the observation image, and a total of three straight lines parallel to the rolling direction were drawn in the measurement area. The average grain size was calculated by counting the number of grain boundaries cut by each straight line using a cutting method in accordance with JIS H0501-1986. This operation was performed on 10 randomly selected, non-overlapping fields, and the arithmetic mean value (value in μm units rounded to the nearest whole number) of the average grain size obtained in each field was adopted as the average grain size of the plate material. Those with an average grain size of 2 to 20 μm were judged to be 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 preparation procedure for 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 membrane was observed by TEM-EDS (TOPCON EM-002B 200 kV), and randomly set 500 μm ２ The Cu-Ti-based precipitates and Cu-Ti-Al-based precipitates present in the observation area were identified based on the EDS quantitative analysis values ​​of Cu, Ti, and Al according to the criteria described in "Identification of Precipitates" above. For each identified precipitate, the number of Cu-Ti-based precipitate particles a with a major axis of 1.0 μm or more and the number of Cu-Ti-Al-based 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 the counted number was 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] For the measurement of the major axis of the precipitate particles (the diameter of the smallest circumscribed circle surrounding the particle), Image J (National Institutes of Health (NIH), Version 1.52a) was used as image analysis software. Analysis using this software was performed under the following conditions. On the "Set Scale" screen displayed by sequentially selecting Analyze and Set Scale, the number of pixels of the scale bar length of the captured TEM image was measured and entered into "Distance in pixels." Next, the length of the scale bar (μm) was entered into "Known distance," the pixel aspect ratio was set to 1.0, and the unit of length was set to μm, so that the size of the precipitate could be recognized on the software. Thereafter, on the "Resize Image Canvas" screen, the Width was set to 2048 pixels, the Height to 1800 pixels, and the Position to Top-Center, and an image of the TEM image portion excluding the scale bar was displayed. After setting this scale and deleting the scale bar display portion, the "Threshold" screen, which is displayed by sequentially selecting Image, Adjust, and Threshold, was used to invert the brightness 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 value was set to a value that would make the proportion of pixels below that value closest to 3% of all pixels, and the presence of precipitate particles was binarized and identified. Thereafter, on the "Analyze Particles" screen of the same software, the area of ​​one independent precipitate region was determined to be 0.00006 μm ２ As a condition for excluding particles with a diameter less than 1.0 μm, Size was set to "0.00006-Infinity." Furthermore, particle analysis was performed under the conditions of Circularity being set to 0.00-1.00 and Fit Ellipse being 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 more and the number density b of precipitate particles with a major axis of 0.3 μm or more in the field of view were determined.

[0057] (Nanoindentation hardness) A sample cut from the test material was embedded in resin so that a cross section parallel to the rolling direction and the thickness direction could be measured, and the measurement surface was prepared by mechanical polishing and colloidal silica mirror polishing. The nanoindentation hardness (GPa) of this measurement surface was measured using the method specified in (X) above to determine the values ​​A and B, and the nanoindentation index Q shown in the formula (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 at 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 the formulas (2) and (3).

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

[0059] (Electrical Conductivity) The electrical conductivity of each test material was measured by the double bridge average cross-sectional area method in accordance with JIS H 0505. Test materials with electrical conductivity of 7.5% IACS or more were judged to be acceptable.

[0060] (MBR / t in 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 in a W-bend test at BW in accordance with the Japan Copper and Brass Association technical standard JCBA T307:2007. The test specimen size was 30 mm in length in the direction perpendicular to the rolling direction and 10 mm in length in the rolling direction. A bending test in which the bending radius was changed in stages was conducted with n = 3 tests for one bending radius, and the minimum bending radius at which no cracks were observed on the surface of the bent portion in all three test specimens was taken as the MBR for that test material. The presence or absence of cracks on the surface of the bent portion was determined in accordance with JCBA T307:2007. For samples judged as having "large wrinkles" in the appearance observation of the bent surface, a specimen was cut perpendicular to the bending axis direction at the deepest wrinkle, and the polished cross section was observed with an optical microscope to check for cracks that propagate into the thickness of the plate. If no such cracks were found, the specimen was judged as having "no cracks observed." A specimen with an MBR / t of 2.00 or less was judged as passing.

[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 Servo Pulser (EHF-EM100k1-020-1A) manufactured by Shimadzu Corporation was used as the tensile fatigue tester. The number of tests (n = 5) was conducted, and the average value expressed with 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] (Burri Height on Punched Surface) A rectangular plate measuring 5 mm x 6 mm with a corner radius of 0.4 mm was punched from 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 burr height at the portion of the two opposing cut edges where the "cut edge normal direction" shown in Figure 4 was parallel to the rolling direction, i.e., the cut edge corresponding to the short side of the rectangle) of the remaining material after punching (the material that had been in contact with the die) was measured using a laser microscope. This measurement was performed on three punched areas, and the arithmetic mean value of the maximum burr heights at each punched area was calculated. This was used as the burr height (μm) for the test material. Burr heights of 3.00 μm or less were judged to pass the test. The results are shown in Tables 1 to 5.

[0063]

[0064]

[0065]

[0066]

[0067]

[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 examples, the major axis of the Cu-Ti-Al precipitate particles b was 5 μm or less.

[0069] In contrast, the comparative examples showed the following results. In No. 41, the Ti content was too high, resulting in excessively high strength and insufficient bending workability. In No. 42, the Ti content was insufficient, resulting in low strength and therefore 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 improvements in fatigue properties and punchability. In No. 44, an Al-free Cu-Ti-based copper alloy (so-called titanium copper) was used. In this case, when the manufacturing process disclosed herein was applied, the Al effect of suppressing the formation of coarse precipitate particles a was not exerted, 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 improvement in punchability.

[0070] In No. 45, the solution treatment temperature was too high, resulting 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. This prevented sufficient strengthening by aging, resulting in a low strength level. Furthermore, the coarse second phase in the cast structure was not solidified sufficiently, resulting in an increased amount of coarse precipitate particles a. However, the amount of precipitate particles b was also large, resulting in acceptable fatigue properties. In No. 47, the reduction ratio in the intermediate cold rolling was too high, resulting in excessive strength and poor bending workability. In No. 48, the aging treatment temperature was too high, resulting in accelerated coalescence of precipitate particles and a decrease in the number density of precipitate particles b. Furthermore, the structure was thought to have been locally weak, resulting in a high indentation index Q. As a result, the fatigue properties and press-punchability were not sufficiently improved. In No. 49, the aging temperature was too low, resulting in insufficient formation of fine precipitates, which are effective in improving strength, and thus the strength level was low. Furthermore, the amount of precipitate particles b formed was insufficient, resulting in poor fatigue properties and press-punchability. Furthermore, the amounts of Ti and Al dissolved in solid solution were large, resulting in low electrical conductivity.

[0071] In No. 50, the reduction ratio of the finish cold rolling was too high, resulting in excessively high strength and poor bending workability. In No. 51, the reduction ratio of the finish cold rolling was too low, resulting in little introduction of processing strain and low strength. In No. 52, the aging treatment temperature was too low, resulting in insufficient generation of precipitate particles b, resulting in poor fatigue properties and press-punchability. Compared to No. 49, this example had high strength due to the introduction of strain by performing intermediate cold rolling, and also had high electrical conductivity due to the low Al content. In No. 53, the reduction ratio of the finish cold rolling was very high, resulting in a higher strength level than No. 1, but on the other hand, the bending workability was poor. In No. 54, the conventional manufacturing process of a 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 the 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-punching properties 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 a grid point at intervals of 4 μm in the rolling direction and 4 μm in the thickness direction, and at each measurement point, nanoindentation hardness (GPa) is measured using a Berkovich indenter under conditions of loading up to a maximum load of 2 mN for 10 seconds, holding for 5 seconds, and unloading for 10 seconds, and the arithmetic mean measurement value calculated excluding the measurement data corresponding to the top 10% and bottom 10% of the total number of measurements in the ranking of all measurement values ​​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) where t (μm) is the thickness of the copper alloy sheet, i is the number of rows of the measurement points in the rolling direction, and j is the number of rows in the thickness direction. 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 at 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 system 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. The copper alloy sheet material according to claim 1, having an electrical conductivity of 7.5% IACS or more.

6. The copper alloy sheet material according to claim 1, 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 in accordance with 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 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 claims 1 to 7 as its material.

9. An electric component using the copper alloy sheet material according to any one of claims 1 to 7 as its material.

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

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