Cu-Ti copper alloy sheet material, manufacturing method thereof, spring member and autofocus camera module

Abstract

To provide a Cu-Ti copper alloy plate with a very high level of strength and reduced density (specific gravity).SOLUTION: A copper alloy plate includes, in mass%, Ti: 2.0-5.0%, Al: 0.5-3.0%, Ag: 0-0.3, B: 0-0.25%, Be: 0-0.2%, Co: 0-1.0%, Cr: 0-1.0%, Fe: 0-1.0%, Mg: 0-1.0%, Mn: 0-1.5%, Nb: 0-0.5%, Ni: 0-1.5%, P: 0-0.2%, S: 0-0.2%, Si: 0-1.0%, Sn: 0-1.5%, V: 0-1.0%, Zn: 0-2.0%, Zr: 0-1.0, and a rare earth element: 0-3.0%, with a total content of Ag, B, Be, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn and Zr of 3.0% or less, a Ti / Al ratio of 1.50 or more, and the balance of Cu and inevitable impurities. The tensile strength in the rolling direction is 1150 MPa or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a high-strength Cu—Ti-based copper alloy sheet material with reduced density (specific gravity) and a method for manufacturing the same, and also to a spring member using the sheet material as its material and an autofocus camera module using the same. [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, so they are used as spring components and current-carrying components for connectors, relays, switches, etc. For example, the spring components incorporated into the autofocus camera modules of mobile electronic devices such as smartphones must be non-magnetic and extremely strong, and Cu-Ti copper alloys are particularly useful as spring components.

[0003] An autofocus camera module is an electronic component unit that includes a lens and a drive mechanism for moving the lens to a predetermined position along the optical axis. Many compact autofocus camera modules control the lens to a predetermined position along the optical axis by balancing a driving force in one direction, such as an electromagnetic force, with a driving force in the opposite direction (a force that returns the lens to its reference position) that utilizes the elasticity of a spring member. While high strength is required for the spring member, it is also important that the spring member itself is lightweight to improve the responsiveness of the lens drive. However, reducing weight by miniaturizing components is not necessarily easy for spring members, which must maintain high strength.

[0004] On the other hand, in order to reduce the weight of metal parts, in addition to miniaturizing the parts, using metals with lower density (specific gravity) is also an effective method. To reduce the density (specific gravity) of copper alloys, it is thought that adding elements such as Al, which has a smaller atomic weight than Cu, is effective.

[0005] Patent Document 1 describes a Cu-Ti-based copper alloy material with improved discoloration resistance and solderability as a conductive spring material suitable for electronic device components such as autofocus camera modules. Al is listed as one of the elements that can be added to the alloy, and the total amount of added elements other than Ti is allowed to be up to 1.0 mass% (Claim 4). Table 1 of Patent Document 1 shows a Cu-Ti-based copper alloy with an Al content of 0.01 mass% (Example 15).

[0006] Patent Document 2 describes a Cu-Ti-based copper alloy material in which the formation of grain boundary reaction-type precipitates is suppressed to improve strength, bending workability, stress relaxation resistance, and fatigue resistance. Patent Document 3 describes a Cu-Ti-based copper alloy material in which a predetermined texture is adjusted to improve bending workability after notching. Although the techniques described in these documents also claim that Al can be added up to a maximum of 1.0 mass%, the Al contents of the materials specifically described are only 0.08% (Patent Document 2, Invention Example 6) and 0.14% (Patent Document 3, Example 9). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2017-172012 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-185370 [Patent Document 3] Japanese Patent Application Laid-Open No. 2010-126777 Summary of the Invention [Problem to be solved by the invention]

[0008] In recent years, with the increasing sophistication of electronic devices, there has been an increasing demand for weight reduction in the individual components used therein. To meet this demand, it is important to also reduce the weight of copper alloy materials used in electronic device components. As mentioned above, in the case of autofocus camera modules, reducing the density (specific gravity) of the spring members used to drive the lens is effective for improving their performance. In order to fully utilize the effect of reducing the density (specific gravity) of Cu-Ti-based copper alloys by adding Al, which has a small atomic weight, it is desirable to set the Al content to 0.5 mass% or more. The Al content of the Cu-Ti-based copper alloys specifically shown in Patent Documents 1 to 3 is at most 0.14 mass%. With this level of Al content, the effect of reducing the density (specific gravity) of Cu-Ti-based copper alloys cannot be fully utilized in electronic device components such as autofocus camera modules.

[0009] The addition of Al to Cu-Ti-based copper alloys poses a problem in that it becomes difficult to maintain a high strength level as the Al content increases. Although the techniques of Patent Documents 1 to 3 state that Al can be added up to a maximum of 1.0 mass%, when an attempt is made to manufacture a Cu-Ti alloy sheet material to which Al is added, for example, 0.5% or more, using the manufacturing methods disclosed in these documents, it is not possible to obtain a sheet material with a very high strength level, such as a tensile strength of 1150 MPa or more.

[0010] The present invention aims to provide a Cu-Ti-based copper alloy sheet material having an extremely high strength level and a reduced density (specific gravity), and also aims to provide a spring member and an autofocus camera module using the same. [Means for solving the problem]

[0011] As a result of detailed investigation, the inventors have found that by adopting a manufacturing process in which a Cu-Ti-based copper alloy containing a predetermined amount of Al to reduce its density (specific gravity) is subjected to solution treatment under predetermined temperature conditions, followed by aging treatment under predetermined temperature conditions, and then finish cold rolling at a high rolling ratio, followed by finish heat treatment (low-temperature annealing) under strictly controlled conditions, it is possible to obtain a plate material that has extremely high strength despite the inclusion of Al. In order to achieve the above object, the present specification discloses the following invention.

[0012] [1]In mass %, Ti: 2.0~5.0%, Al: 0.5~3.0%, Ag: 0~0.3%, B: 0~0.25%, Be: 0~0.2%, Co: 0~1.0%, Cr: 0~1.0%, Fe: 0~1.0%, Mg:0~1.0%, Mn:0~1.5%, Nb:0~0.5%, Ni:0~1.5%, P:0~0.2%, S:0~0.2%, Si:0~1.0%, Sn:0~1.5%, V Zn: 0-1.0%, Zr: 0-1.0%, and among the elements, the total content of Ag, B, Be, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn and Zr is 3.0% or less, the Ti / Al ratio is 1.50 or more, and the remainder is Cu and unavoidable impurities, and the tensile strength in the rolling direction is 1150 MPa or more. [2] The copper alloy sheet material according to the above [1], further having a composition containing rare earth elements in a total amount of 3.0 mass% or less. [3] The copper alloy sheet material according to the above [1] or [2], wherein, in measurements of a measurement area provided on a cross section perpendicular to the rolling direction by EBSD (electron backscatter diffraction) with a step size of 0.02 μm, the average grain size is 1.0 μm or less when measured by the Area Fraction method, assuming that boundaries with a crystal orientation difference of 5° or more are grain boundaries. [4] The copper alloy sheet material according to any one of the above [1] to [3], having a crystal orientation such that the X-ray diffraction intensity ratio A represented by the following formula (1) is 0.50 or more in the X-ray diffraction pattern of the sheet surface: A=I{220} / (I{111}+I{200}+I{220}+I{311}+I{331}+I{420}) …(1) Here, I{hkl} is the integrated intensity of the diffraction peak of the Cu matrix {hkl} crystal plane. [5] The number density of coarse precipitate particles with a major axis of 1.0 μm or more on an observation surface parallel to the plate surface is 1.0 × 10 5 pieces / mm 2 The copper alloy sheet material according to any one of the above [1] to [4], which is: [6] In measurements of a measurement area provided on a cross section perpendicular to the rolling direction by EBSD (electron backscatter diffraction) with a step size of 0.02 μm, the average grain size by the Area Fraction method, assuming that boundaries with a crystal orientation difference of 5° or more are considered to be grain boundaries, is 1.0 μm or less, and the X-ray diffraction pattern of the sheet surface has a crystal orientation such that the X-ray diffraction intensity ratio A expressed by the following formula (1) is 0.50 or more, and the number density of coarse precipitate particles with a major axis of 1.0 μm or more on an observation surface parallel to the sheet surface is 1.0 × 10 5 pieces / mm 2 The copper alloy sheet material according to any one of the above [1] to [5], which is: A=I{220} / (I{111}+I{200}+I{220}+I{311}+I{331}+I{420}) …(1) Here, I{hkl} is the integrated intensity of the diffraction peak of the Cu matrix {hkl} crystal plane. [7] Density is 8.55g / cm 3 The copper alloy sheet material according to any one of the above [1] to [6], which is: [8] The copper alloy sheet material according to any one of the above [1] to [7], having a sheet thickness of 0.015 to 0.15 mm. [9] In a process for producing a copper alloy sheet material by subjecting an intermediate product sheet material having a composition specified in the above [1] to solution treatment, aging treatment, finish cold rolling, and finish heat treatment in the above order, Solution treatment is carried out under conditions of maintaining the temperature in the range of 750 to 970°C, Aging treatment is carried out at an aging temperature of 300 to 520°C. Finish cold rolling is performed at a rolling ratio of 90% or more, The finish heat treatment is carried out under the conditions of holding the temperature T (°C) that satisfies the following formulas (2) to (4) within a time range of t0 ± δ (seconds) determined by the reference time t0 (seconds) that satisfies the following formulas (2) to (4) and the allowable fluctuation time δ (seconds) expressed by the following formula (5-1) or the following formula (5-2), The method for producing a copper alloy sheet material according to any one of the above [1], [3] to [8]. 280≦T≦520 …(2) t0≧30 …(3) t0=125×Ti+200×Al-1.15×T…(4) When 30≦t0<100, δ=10 …(5-1) When t0≧100, δ=0.1×t0…(5-2) Here, t0 is the reference time (seconds), T is the holding temperature (°C) in the range of 280 to 520°C, and δ is the allowable fluctuation time (seconds). The element symbols Ti and Al in equation (4) are substituted with the Ti content (mass%) and Al content (mass%) of the sheet material, respectively.

[10] The method for producing a copper alloy sheet according to the above [9], wherein the intermediate product sheet further has a composition containing rare earth elements in a range of 3.0 mass% or less in total.

[11] A spring member using the copper alloy sheet material according to any one of [1] to [8] above as its material.

[12] A spring member for an autofocus camera module, which uses the copper alloy sheet material according to any one of [1] to [8] above as its material.

[13] An autofocus camera module comprising a lens, a driving force imparting means for driving the lens in the optical axis direction, and a spring member for urging the lens to a reference position in the optical axis direction, wherein the copper alloy sheet material according to any one of [1] to [8] above is used as the material of the spring member.

[0013] In this specification, the "sheet material" means a sheet-like metal material formed by utilizing the malleability of metal. A thin sheet-like metal material may also be called "foil", and such "foil" is also included in the "sheet material" referred to here. A long sheet-like metal material wound in a coil shape is also included in the "sheet material". In this specification, the thickness of the sheet-like metal material is called the "sheet thickness". Further, the "sheet surface" is a surface perpendicular to the sheet thickness direction of the sheet material. The "sheet surface" may also be called the "rolling surface". In this specification, the notation "n1~n2" indicating a numerical range means "n1 or more and n2 or less". Here, n1 and n2 are numerical values satisfying n1 < n2.

Advantages of the Invention

[0014] According to the present invention, in a Cu-Ti-based copper alloy sheet material having a very high strength with a tensile strength of 1150 MPa or more, it has become possible to reduce the density (specific gravity) of the alloy. This copper alloy sheet material is useful for weight reduction and performance improvement of electronic devices that require a non-magnetic high-strength spring material. In particular, in an autofocus camera module, it can contribute to an improvement in lens driving performance.

Brief Description of the Drawings

[0015] [Figure 1] A figure illustrating a SEM image of an observation surface showing coarse precipitates for Invention Example No. 1. [Figure 2] A figure illustrating an image obtained by binarizing the image of FIG. 1 so as to identify the presence portion of precipitate particles. [Figure 3] A figure illustrating a SEM image of an observation surface showing coarse precipitates for Comparative Example No. 35. [Figure 4] A figure illustrating an image obtained by binarizing the image of FIG. 3 so as to identify the presence portion of precipitate particles. [Figure 5] A figure illustrating X-ray diffraction patterns near the {220} peak for the sheet material before and after the final heat treatment of Invention Example No. 1. [[ID=3l]]

Embodiments for Carrying Out the Invention

[0016] [Chemical composition] Hereinafter, "%" regarding alloy components means "% by mass" unless otherwise specified.

[0017] Titanium (Ti) is an element that contributes to increasing the strength of Cu-Ti-based copper alloys 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, we focus on alloys with a Ti content of 2.0% or more. The Ti content is preferably 2.5% or more, and may be controlled to 3.0% or more. Excessive Ti content reduces hot workability and cold workability, so the Ti content is set to 5.0% or less. It may also be controlled to 4.5% or less, or 4.0% or less.

[0018] Aluminum (Al) is an effective element for reducing the density (specific gravity) of Cu-Ti-based copper alloys. To fully utilize this effect, an Al content of 0.5% or more is required. 0.7% or more is more effective, and 1.0% or more is even more effective. Conventionally, when Cu-Ti-based copper alloys contain 0.5% or more Al, it has been difficult to obtain high-strength sheet materials. However, this problem can be solved by the manufacturing method described below. However, if the Al content is too high, Ti-Al-based precipitates are likely to form, resulting in a large amount of coarse precipitates. Therefore, the Al content must be limited to 3.0% or less, and the Al content must be adjusted so that the Ti / Al ratio is 1.50 or more. The Ti / Al ratio is the ratio of the Ti content to the Al content expressed in mass%. Although there is no particular upper limit to the Ti / Al ratio, if Ti is excessively large relative to Al, it may lead to an increase in the production cost of the copper alloy sheet material and may reduce the effect of reducing the density (specific gravity). Therefore, the Ti / Al ratio is preferably set in the range of, for example, 9.0 or less, and may be controlled to 5.5 or less.

[0019] Ag (silver), B (boron), Be (beryllium), Co (cobalt), Cr (chromium), Fe (iron), Mg (magnesium), Mn (manganese), Nb (niobium), Ni (nickel), P (phosphorus), S (sulfur), Si (silicon), Sn (tin), V (vanadium), Zn (zinc), and Zr (zirconium) are optional elements. One or more of these may be contained as needed.

[0020] Among the optional elements listed above, Ni, Co, and Fe form intermetallic compounds with Ti, contributing to improved strength. Furthermore, these intermetallic compounds inhibit grain coarsening, enabling solution treatment at higher temperatures and favoring sufficient Ti solid solution. Ag and Sn improve stress relaxation resistance. Be is effective in improving fatigue properties. Zn improves solderability and strength, as well as castability. Mg improves stress relaxation resistance and has a desulfurizing effect. Si can form compounds with Ti. Cr, Nb, and Zr are effective in dispersion strengthening and inhibiting grain coarsening. Mn and V readily form high-melting-point compounds with S and other elements, and B and P have the effect of refining the cast structure, each contributing to improved hot workability. The inclusion of an appropriate amount of S is effective in improving press-punching properties.

[0021] The contents of the above optional elements are preferably within the ranges of Ag: 0-0.3%, B: 0-0.25%, Be: 0-0.2%, Co: 0-1.0%, Cr: 0-1.0%, Fe: 0-1.0%, Mg: 0-1.0%, Mn: 0-1.5%, Nb: 0-0.5%, Ni: 0-1.5%, P: 0-0.2%, S: 0-0.2%, Si: 0-1.0%, Sn: 0-1.5%, V: 0-1.0%, Zn: 0-2.0%, and Zr: 0-1.0%. When one or more of Ag, B, Be, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, and Zr are contained, it is more effective to set the total content thereof to 0.05% or more. However, the total content of these elements must not exceed 3.0%.

[0022] More preferred contents of the above optional elements include Ag: 0-0.25%, B: 0-0.2%, Be: 0-0.15%, Co: 0-0.3%, Cr: 0-0.5%, Fe: 0-0.4%, Mg: 0-0.4%, Mn: 0-0.5%, Nb: 0-0.25%, Ni: 0-0.25%, P: 0-0.15%, S: 0-0.02%, Si: 0-0.08%, Sn: 0-0.7%, V: 0-0.25%, Zn: 0-0.9%, and Zr: 0-0.3%. The total content of Ag, B, Be, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, and Zr is more preferably 1.5% or less.

[0023] More preferred contents of the above optional elements include Ag: 0-0.16%, B: 0-0.15%, Be: 0-0.12%, Co: 0-0.18%, Cr: 0-0.3%, Fe: 0-0.23%, Mg: 0-0.26%, Mn: 0-0.31%, Nb: 0-0.16%, Ni: 0-0.16%, P: 0-0.12%, S: 0-0.012%, Si: 0-0.05%, Sn: 0-0.42%, V: 0-0.15%, Zn: 0-0.6%, and Zr: 0-0.16%. The total content of Ag, B, Be, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, and Zr is more preferably 0.6% or less.

[0024] In addition to the above elements, rare earth elements (REM) can be contained. Rare earth elements are Sc (scandium), Y (yttrium), and lanthanoid elements of Group 3 of the periodic table. The inclusion of rare earth elements is effective in refining crystal grains and dispersing precipitates. When rare earth elements are contained, it is more effective to set the total content to 0.01% or more. However, from the standpoint of economic efficiency, the total content of rare earth elements is preferably 3.0% or less, more preferably 1.5% or less, and may be controlled to 0.8% or less, or 0.6% or less.

[0025] A specific range of rare earth element content can be, for example, a range containing, in mass %, one or more selected from La (lanthanum): 2.0% or less, Ce (cerium): 1.5% or less, Pr (praseodymium): 0.4% or less, Nd (neodymium): 0.6% or less, Sm (samarium): 1.5% or less, and Y (yttrium): 1.2% or less, with the total rare earth element content being 3.0% or less.

[0026] A preferred content range of rare earth elements taking into consideration economic efficiency and manufacturability is, for example, a range containing, in mass %, one or more elements selected from La: 0.35% or less, Ce: 0.3% or less, Pr: 0.05% or less, Nd: 0.2% or less, Sm: 1.0% or less, and Y: 1.0% or less, with the total content of rare earth elements being 1.5% or less.

[0027] A more preferable content range of rare earth elements that takes economical efficiency and manufacturability into further consideration is, for example, a range that includes, in mass %, one or more elements selected from La: 0.30% or less, Ce: 0.25% or less, Pr: 0.03% or less, Nd: 0.10% or less, Sm: 0.5% or less, and Y: 0.45% or less, with the total content of rare earth elements being 0.6% or less.

[0028] [Tensile strength] In order to stably exert a high elastic force in spring members used in autofocus camera modules and the like, the present invention targets a high-strength Cu-Ti-based copper alloy sheet material having an extremely high rolling direction tensile strength of 1150 MPa or more. The rolling direction tensile strength can be adjusted to 1200 MPa or more, or 1300 MPa or more, more preferably 1350 MPa or more, even more preferably 1400 MPa or more, and particularly preferably 1450 MPa or more. There is no particular upper limit to the tensile strength, but it may be adjusted to, for example, a range of 1800 MPa or less.

[0029] [Average grain size] In order to achieve extremely high strength, the copper alloy sheet material of the present invention is adjusted to a microstructure state with fine crystal grains by, for example, applying high-reduction cold rolling in the finish cold rolling described below. Specifically, the present invention is suitable for copper alloy sheets having an average crystal grain size of 1.0 μm or less, as measured by the Area Fraction method using EBSD (electron backscatter diffraction) with a step size of 0.02 μm in a measurement area on a cross section perpendicular to the rolling direction, where boundaries with a crystal orientation difference of 5° or more are considered to be crystal grain boundaries. From the viewpoint of strength, the average crystal grain size is more preferably 0.8 μm or less, and particularly preferably 0.7 μm or less. Since extremely fine crystal grains increase production costs, the average crystal grain size may be adjusted to, for example, a range of 0.1 μm or more, or may be adjusted to a range of 0.2 μm or more. The average crystal grain size can be determined by the following method.

[0030] (How to determine the average grain size) A cross section perpendicular to the rolling direction of the sheet material was buffed and then smoothed by ion milling to obtain an observation surface. The observation surface was observed using a field emission scanning electron microscope (FE-SEM) at 10,000x magnification. A measurement area including the center of the sheet thickness was randomly selected, and the crystal orientation of that measurement area was measured using electron backscatter diffraction (EBSD) with a step size (measurement pitch) of 0.02 μm. Using EBSD data analysis software, boundaries with a misorientation of 5° or more were considered grain boundaries. The grain size of all grains within the measurement area was determined using a diameter chart, and the average grain size was calculated using the area fraction method. For grains that partially extend beyond the boundaries of the measurement area, the area of ​​the portion within the measurement area was used to calculate the average grain size. This procedure was performed on five randomly selected, non-overlapping measurement areas, and the arithmetic mean of the average grain size values ​​obtained in the five fields was determined as the average grain size (μm). Note that twin boundaries are also considered grain boundaries.

[0031] [X-ray diffraction intensity ratio A] Furthermore, the present invention is preferably directed to a material having a crystal orientation in which the X-ray diffraction intensity ratio A, expressed by the following formula (1), is 0.50 or more in the X-ray diffraction pattern of the plate surface. A=I{220} / (I{111}+I{200}+I{220}+I{311}+I{331}+I{420}) …(1) Here, I{hkl} is the integrated intensity of the diffraction peak of the Cu matrix {hkl} crystal plane. Since the copper alloy sheet of the present invention exhibits a metal structure in which a precipitate phase exists in the Cu matrix, which is the metal base, the diffraction peak of the precipitate phase is also detected in the X-ray diffraction pattern. When determining the above X-ray diffraction intensity ratio A, attention is paid to the diffraction peak of the Cu matrix crystal.

[0032] In crystal orientations where the peak intensity of the {220} crystal plane is relatively high as described above, it is believed that even finer subgrains are formed within the crystal grains identified by the EBSD analysis described above, and the formation of these subgrains is presumed to contribute to the significant improvement in strength. Furthermore, the {220} crystal plane itself suppresses slip deformation, which is presumed to also contribute to the improvement in strength. From the perspective of increasing strength, it is more effective for the X-ray diffraction intensity ratio A to be 0.55 or higher, and even more effective for it to be 0.60 or higher. There is no particular upper limit for the X-ray diffraction intensity ratio A, but it can be controlled to, for example, 0.90 or lower. The X-ray diffraction intensity ratio A can be determined by the following method.

[0033] (How to calculate the X-ray diffraction intensity ratio A) For the sheet surface (rolled surface), an X-ray diffraction pattern covering the diffraction angle 2θ range of 40° to 150° is measured using an X-ray diffractometer under the following conditions: Cu-Kα radiation, tube voltage 30 kV, tube current 10 mA, measurement step 0.04°, and measurement time per step 0.1 seconds. The measurement is performed while rotating the sample at 15 revolutions per minute, with the sheet thickness direction as the axis of rotation. Based on the obtained X-ray diffraction pattern data, X-ray diffraction pattern analysis software is used to fit the pseudo-Voigt function to determine the integrated intensity I{hkl} of each {hkl} peak. The obtained I{hkl} values ​​are substituted into the above equation (1) to calculate the X-ray diffraction intensity ratio A value. The 2θ ranges corresponding to {111}, {200}, {220}, {311}, {331}, and {420} are 38° to 48°, 45° to 55°, 68° to 78°, 75° to 80°, 132° to 142°, and 142° to 150°, respectively.

[0034] [Number density of coarse precipitate particles] If the amount of coarse precipitates is large, it may be difficult to stably achieve the above-mentioned extremely high strength level. In the present invention, the number density of coarse precipitate particles with a major axis of 1.0 μm or more on an observation surface parallel to the sheet surface is 1.0 × 10 5 pieces / mm 2 From the viewpoint of increasing strength, the number density of coarse precipitate particles is 1.0 × 10 4 pieces / mm 2 It is more effective that the number of coarse precipitate particles is less than 5.0 × 10. However, it is difficult to completely prevent the generation of coarse precipitate particles in manufacturing. 2 pieces / mm 2 That's all. The number density of the coarse precipitate particles can be determined by the following method.

[0035] (How to determine the number density of coarse precipitate particles) The plate surface was electrolytically polished under the following electrolytic polishing conditions to dissolve only the Cu base of the copper alloy plate material, thereby exposing the precipitate particles. The surface was then ultrasonically cleaned in ethanol for 20 minutes using an ultrasonic cleaner. The surface was then observed using a field emission scanning electron microscope (FE-SEM) at an acceleration voltage of 15 kV and a magnification of 5000x. The total number of precipitate particles with a major axis of 1.0 μm or more observed on the FE-SEM image was calculated based on the total observation area (mm 2 ) is the number density of coarse precipitate particles (particles / mm 2 ) for the secondary electron image of the FE-SEM. After focusing at a magnification of 5000x, the color tone is adjusted using auto-contrast. At this time, the image in the same field of view may be burned by the electron beam, causing a change in color tone, so the observation is carried out in a different field of view from the one used for auto-contrast. This is done to prevent variations in the precipitate number density results due to brightness threshold adjustment in the binarization process of coarse precipitates, which will be described later. The total observation area is 0.1 mm2 in total, using multiple randomly set, non-overlapping observation fields. 2 That is all. Precipitate particles that partially protrude from the observation field are counted if the portion that appears within the observation field is assumed to be the entire particle and its major axis is 1.0 μm or more. To measure the major axis of precipitate particles, SEM images (secondary electron images) are binarized using image analysis software to identify the areas where precipitate particles exist, the outline of each precipitate particle is approximated as an ellipse, and the length of the major axis of this ellipse (however, if the ellipse is a perfect circle, the diameter of the circle) can be used as the major axis.

[0036] (Electrolytic polishing conditions) Electrolyte: Distilled water, phosphoric acid, ethanol, and 2-propanol mixed in a volume ratio of 10:5:5:1 Liquid temperature: 20℃ Voltage: 15V ·Electrolysis time: 20 seconds

[0037] [density] A copper alloy sheet with a very high strength level of 1150 MPa or more in the rolling direction and a density of 8.55 g / cm 3If the density is reduced to or below 8.55 g / cm, the spring member obtained by processing it is considered to be highly effective in improving the performance of equipment as a part involved in the operation of equipment that requires accurate and quick response, such as an autofocus camera module. Since the atomic weight order of Cu, Ti, and Al is Cu>Ti>Al, increasing the Al content is the most effective way to reduce the density (specific gravity) of Cu-Ti-based copper alloys, but the effect of the Ti content cannot be ignored. Although the contents of Al and Ti are limited in order to adjust to the extremely high strength level mentioned above, according to the present invention, it is possible to reduce the density at 20°C to 8.55 g / cm. 3 In Cu-Ti alloys, the density can be reduced to 8.55 g / cm3 or less while the tensile strength in the rolling direction is increased to 1150 MPa or more. 3 It has been difficult to reduce the density to 8.43 g / cm or less using conventional techniques. 3 Adjust to below 8.39g / cm 3 The density can be adjusted to the following value: The lower limit of the density is not particularly limited, but for example, it can be adjusted to 7.7 g / cm 3 The adjustment may be made within the above range.

[0038] [Manufacturing method] The copper alloy sheet material described above can be manufactured, for example, by the following manufacturing process. Melting and casting → heating of cast slabs → hot working → rough cold rolling → solution treatment → aging treatment → finish cold rolling → finish heat treatment 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. Each of the above steps will be described below.

[0039] [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 process in an inert gas atmosphere or a vacuum melting furnace.

[0040] [Slab heating] The slab can be heated before hot working by, for example, holding it at 900 to 970°C for 0.5 to 5 hours.

[0041] [Hot processing, rough cold rolling] The hot working method is not particularly limited. Usually, hot forging or hot rolling is adopted. In the case of hot rolling, the total hot rolling reduction ratio may be, for example, 60 to 97%. 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". Rough cold rolling can be a process in which the process of "intermediate annealing + cold rolling" is added multiple times as needed. The rolling reduction ratio of rough cold rolling (the rolling reduction ratio of the final cold rolling when multiple cold rollings are performed) can be, for example, 50 to 99%. In this way, an intermediate product sheet material to be subjected to solution treatment can be obtained.

[0042] Here, the rolling ratio is expressed by the following formula (6). Rolling ratio (%) = 100 × (h0 - h1) / h0…(6) h0: Plate thickness before rolling (mm) h1: thickness after rolling (mm)

[0043] [Solution treatment] The intermediate product sheet material is subjected to solution treatment under conditions of holding in the temperature range of 750 to 970°C. If the solution treatment temperature is too low, it becomes difficult to sufficiently solidify the coarse precipitates present after hot working, and the number density of coarse precipitates becomes high in the final copper alloy sheet material. If the solution treatment temperature is too high, coarsening of recrystallized grains occurs, making it difficult to sufficiently refine the crystal grains in the process described below. In either case, high strength cannot be obtained in the end. The holding time in the temperature range of 750 to 970°C may be set, for example, in the range of 60 to 1200 seconds.

[0044] [Aging treatment] After the solution treatment, the material is subjected to aging treatment at 300 to 520°C, preferably 320 to 500°C, to form fine precipitates that contribute to strength. The aging treatment time (holding time at 300 to 520°C) can usually be set within the range of 1 to 24 hours to obtain a sufficient effect.

[0045] [Finishing cold rolling] In the present invention, cold rolling is performed at a rolling reduction of 90% or more after the above-mentioned aging treatment. Cold rolling at this stage is referred to as "finish cold rolling" in this specification. If the rolling reduction in the finish cold rolling is too low, the crystal grains are likely to be insufficiently refined, and it becomes difficult to obtain a texture with the above-mentioned predetermined crystal orientation. In this case, high strength cannot be achieved. It is more effective to set the rolling reduction in the finish cold rolling to 95% or more. There is no particular upper limit to the rolling reduction in the finish cold rolling, but it may be set to, for example, a range of 99.5% or less depending on the capacity of the rolling mill.

[0046] [Finishing heat treatment] After the finish cold rolling, the material is subjected to a final heat treatment in which the temperature is maintained in the range of 280 to 520°C. This heat treatment is referred to as "finish heat treatment" in this specification. In order to stably achieve a high strength of tensile strength of 1150 MPa or more in a Cu-Ti-based copper alloy sheet material to which a predetermined amount of Al is added, it is important to strictly control the conditions of the finish heat treatment according to the contents of Ti and Al. This allows a copper alloy sheet material to be obtained whose X-ray diffraction intensity ratio A is within the range described above.

[0047] Specifically, the control is performed under the condition that the temperature is maintained at a holding temperature T (°C) that satisfies the following formulas (2) to (4) within a time range of t0±δ (seconds) that is determined by a reference time t0 (seconds) that satisfies the following formulas (2) to (4) and an allowable fluctuation time δ (seconds) that is expressed by the following formula (5-1) or (5-2). 280≦T≦520 …(2) t0≧30 …(3) t0=125×Ti+200×Al-1.15×T…(4) When 30≦t0<100, δ=10 …(5-1) When t0≧100, δ=0.1×t0…(5-2) Here, t0 is the reference time (seconds), T is the holding temperature (°C) in the range of 280 to 520°C, and δ is the allowable fluctuation time (seconds). The element symbols Ti and Al in equation (4) are substituted with the Ti content (mass%) and Al content (mass%) of the sheet material, respectively.

[0048] The holding temperature T (°C) can be the furnace temperature, and the holding time represented by t0±δ (seconds) can be the time the material stays in the furnace at temperature T (°C) (furnace time). When the holding temperature is not constant (for example, when the material is passed through a continuous annealing furnace having zones with different set temperatures), the time-average furnace temperature while the material stays in the temperature range of 280 to 520°C can be used as the holding temperature T.

[0049] In this way, a high-strength Cu—Ti-based copper alloy sheet material with reduced density (specific gravity) can be obtained. The thickness of this sheet material can be, for example, 0.015 to 0.15 mm, and may also be controlled in the range of 0.020 to 0.100 mm, or 0.03 to 0.06 mm.

[0050] [Spring member] The above Cu-Ti based copper alloy sheet material can be used as a material and processed by press forming, etching, etc. to obtain a spring member for use in an autofocus camera module or the like.

[0051] [Autofocus camera module] An example of an autofocus camera module that is expected to have particularly improved performance due to a spring member made from the copper alloy sheet material of the present invention is one that includes a lens, a driving force applying means for driving the lens in the optical axis direction, and a spring member (manufactured by press molding or the like using the copper alloy sheet material of the present invention as a material) for urging the lens to a reference position in the optical axis direction. [Example]

[0052] Copper alloys having the chemical compositions shown in Table 1 were melted and cast. In Inventive Example No. 15, misch metal (a mixture of rare earth elements) was added as a source of rare earth elements in a proportion of 0.25 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.

[0053] The cast slabs obtained by casting were heated at the temperatures and times shown in Tables 2 and 3, and then removed from the heating furnace and hot-rolled to the thicknesses shown in Tables 2 and 3, followed by water quenching. The total hot-rolling reduction was 90%. Except for some examples (Comparative Examples Nos. 31 and 45), the surface oxide layer was removed (face milled) by mechanical polishing after hot rolling, and each hot-rolled material was subjected to rough cold rolling to the thicknesses shown in the "Rough Cold Rolling" column in Tables 2 and 3. For Nos. 31 and 45, cracks occurred in the material during hot rolling, so the subsequent process was discontinued.

[0054] After rough cold rolling, the intermediate product sheets were subjected to solution treatment, aging treatment, and finish cold rolling in the order shown in Tables 2 and 3. The aging treatment was carried out in a nitrogen atmosphere using a batch-type heat treatment furnace. Then, except for some examples (Comparative Example No. 39), the sheets were subjected to finish heat treatment under the conditions shown in Tables 2 and 3. Finish heat treatment was omitted for No. 39. Tables 2 and 3 show the thickness of the final sheets. These sheets were used as test materials for the following investigations. The density (specific gravity) was measured using block samples cut from the material after the slab heating stage.

[0055] (Average grain size) According to the "Method for determining average grain size" mentioned above, the observation surface formed on the cross section perpendicular to the rolling direction of the test material was observed using an FE-SEM (JSM-7200F manufactured by JEOL Ltd.), and the average grain size was determined using an EBSD device (Symmetry manufactured by Oxford Instruments) installed in the FE-SEM. The EBSD data analysis software used was OIM-Analysis 7.3.1 manufactured by TSL Solutions Co., Ltd.

[0056] (Number density of coarse precipitate particles) The number density of coarse precipitate particles was determined according to the "Method for determining the number density of coarse precipitate particles" mentioned above. Image-J (Ver. 1.52a) was used as image analysis software. For SEM images (secondary electron images), the brightness was inverted using a threshold setting so that the lowest brightness pixel of all pixels was 255 and the highest brightness pixel was 0. The gradation was then binarized so that pixels with a brightness of 125 or less were black and pixels with a brightness of more than 125 were white, and the matrix (white areas) and precipitates (black areas) were distinguished. Ellipses was selected in particle analysis, and the major axis of each particle was determined by approximating the outline of each precipitate particle with an ellipse.

[0057] Figure 1 shows an example of an SEM image of the observation surface revealing coarse precipitates for Inventive Example No. 1. Figure 2 shows an example of an image obtained by binarizing the image of Figure 1 so that the areas where precipitate particles exist can be identified. Figure 3 shows an example of an SEM image of the observation surface revealing coarse precipitates for Comparative Example No. 35. Figure 4 shows an example of an image obtained by binarizing the image of Figure 3 so that the areas where precipitate particles exist can be identified.

[0058] (X-ray diffraction intensity ratio A) According to the "Method for Determining the X-ray Diffraction Intensity Ratio A" described above, the X-ray diffraction patterns of the plate surfaces (rolled surfaces) of samples (20 mm × 20 mm) cut from each test material were measured using an X-ray diffractometer (D2 Phaser 2nd Generation, manufactured by Burker AXS) under conditions of Cu-Kα radiation, tube voltage of 30 kV, and tube current of 10 mA. The X-ray diffraction pattern analysis software used was Topas (Ver. 5) manufactured by Burker AXS, and the integrated intensity I{hkl} of each {hkl} peak was determined, and the X-ray diffraction intensity ratio A was calculated using the above-mentioned formula (1).

[0059] Figure 5 shows the X-ray diffraction pattern near the {220} peak measured for the specimen of Invention Example No. 1 (sheet material after finish heat treatment) as an example, shown by the dashed line. This figure also shows the X-ray diffraction pattern measured in the same manner for the sheet material of Invention Example No. 1 before finish heat treatment (after finish cold rolling), shown by the solid line. It can be seen that the finish heat treatment increased the integrated intensity of the {220} plane. Furthermore, this finish heat treatment increased the X-ray diffraction intensity ratio A.

[0060] (tensile strength) Tensile test pieces (JIS No. 13B) were taken from each test material in the rolling direction, 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.

[0061] (density) The density at room temperature (20°C) was measured by the Archimedes method (underwater gravitational method) using a block sample with a mass of 10 g cut out from the material after the slab heating. The above results are shown in Tables 4 and 5.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] [Table 4]

[0066] [Table 5]

[0067] All of the plate materials of the present invention, in which the chemical composition and manufacturing conditions were strictly controlled in accordance with the above-mentioned regulations, exhibited extremely high strength levels and were also excellent in reducing density (specific gravity).

[0068] In contrast, the comparative example No. 31 had an excessively high Ti content, which caused cracks in the material during hot rolling. No. 32 had too little Ti content, resulting in low strength and an insufficient effect in reducing density (specific gravity). No. 33 had too much Al, which resulted in a large number of coarse precipitates and low strength. No. 34 had an insufficient effect in reducing density (specific gravity) because the Al content was too low. No. 35 had a small Ti / Al ratio, resulting in a large number of coarse precipitates and low strength. In No. 36, the rolling ratio in the finish cold rolling was low, so the average crystal grain size was large and the strength was low. For No. 37, the holding temperature in the finish heat treatment was high, resulting in a large amount of coarse precipitates and low strength. For No. 38, the holding temperature in the finish heat treatment was low, resulting in a texture with a low X-ray diffraction intensity ratio A of the {220} plane, and low strength. No. 39 was not subjected to finish heat treatment, and therefore had a texture with a low X-ray diffraction intensity ratio A of the {220} plane, resulting in low strength. For No. 40, the finish heat treatment time was too long, outside the range of "reference time t0 ± allowable fluctuation time δ," resulting in a large number of coarse precipitates and low strength. For No. 41, the finish heat treatment time was too short, outside the range of "reference time t0 ± allowable fluctuation time δ," resulting in a texture with a low X-ray diffraction intensity ratio A of the {220} plane and low strength. In No. 42, the solution treatment temperature was too high, causing the recrystallized grains to coarsen during the solution treatment, and even after going through the subsequent processes, the final average crystal grain size remained large, resulting in low strength. In No. 43, the solution treatment temperature was too low, so the precipitates present in the copper alloy structure after hot rolling were not sufficiently dissolved during the solution treatment and remained. Even after the subsequent processes, the final structure was one with many coarse precipitates, resulting in low strength. In No. 44, the aging temperature was too high, resulting in a large number of coarse precipitates and low strength. In No. 45, the total amount of optional elements other than Ti and Al was too high, causing cracks in the material during hot rolling. In No. 46, the rolling ratio in the finish cold rolling was low, so the average crystal grain size was large and the strength was low.

Claims

1. In mass%, Ti: 2.0 to 5.0%, Al: 0.5 to 3.0%, Ag: 0 to 0.3%, B: 0 to 0.25%, Be: 0 to 0.2%, Co: 0 to 1.0%, Cr: 0 to 1.0%, Fe: 0 to 1.0%, Mg: 0 to 1.0%, Mn: 0 to 1.5%, Nb: 0 to 0.5%, Ni: 0 to 1.5%, P: 0 to 0.2%, S: 0 to 0.2%, Si: 0 to 1.0%, Sn: 0 to 1.5%, V: 0 to 1.0%, Zn: 0 to 2.0%, Zr: 0 to 1.0%, and among the above elements, Ag, B, Be, C a copper alloy sheet material having a composition in which the total content of O, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, and Zr is 3.0% or less, the Ti / Al ratio is 1.50 or more, the balance being Cu and unavoidable impurities, the tensile strength in the rolling direction is 1150 MPa or more, and the average grain size is 1.0 μm or less, as determined by the area fraction method when boundaries with a crystal orientation difference of 5° or more are considered to be grain boundaries, in measurement by EBSD (electron backscatter diffraction) with a step size of 0.02 μm in a measurement region provided on a cross section perpendicular to the rolling direction.

2. In mass%, Ti: 2.0 to 5.0%, Al: 0.5 to 3.0%, Ag: 0 to 0.3%, B: 0 to 0.25%, Be: 0 to 0.2%, Co: 0 to 1.0%, Cr: 0 to 1.0%, Fe: 0 to 1.0%, Mg: 0 to 1.0%. , Mn: 0-1.5%, Nb: 0-0.5%, Ni: 0-1.5%, P: 0-0.2%, S: 0-0.2%, Si: 0-1.0%, Sn: 0-1.5%, V: 0-1.0%, Zn: 0-2.0%, Zr: 0-1.0%. and a copper alloy sheet material having a composition in which the total content of Ag, B, Be, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, and Zr among the elements is 3.0% or less, the Ti / Al ratio is 1.50 or more, and the balance is Cu and unavoidable impurities, the tensile strength in the rolling direction is 1150 MPa or more, and the X-ray diffraction pattern of the sheet surface has a crystal orientation in which the X-ray diffraction intensity ratio A represented by the following formula (1) is 0.50 or more. A=I{220} / (I{111}+I{200}+I{220}+I{311}+I{331}+I{420})...(1) Here, I{hkl} is the integrated intensity of the diffraction peak of the Cu parent phase {hkl} crystal plane.

3. In mass%, Ti: 2.0-5.0%, Al: 0.5-3.0%, Ag: 0-0.3%, B: 0-0.25%, Be: 0-0.2%, Co: 0-1.0%, Cr: 0-1.0%, Fe: 0-1.0%, Mg: 0- 1.0%, Mn: 0-1.5%, Nb: 0-0.5%, Ni: 0-1.5%, P: 0-0.2%, S: 0-0.2%, Si: 0-1.0%, Sn: 0-1.5%, V: 0-1.0%, Zn: 0-2.0%, Zr : 0 to 1.0%, and among the elements, the total content of Ag, B, Be, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, and Zr is 3.0% or less, the Ti / Al ratio is 1.50 or more, and the balance is Cu and unavoidable impurities, the tensile strength in the rolling direction is 1150 MPa or more, and the number density of coarse precipitate particles with a major axis of 1.0 μm or more in an observation plane parallel to the sheet surface is 1.0 × 10 ５ pieces / mm ２ The following is a copper alloy sheet material.

4. In mass%, Ti: 2.0 to 5.0%, Al: 0.5 to 3.0%, Ag: 0 to 0.3%, B: 0 to 0.25%, Be: 0 to 0.2%, Co: 0 to 1.0%, Cr: 0 to 1.0%, Fe: 0 to 1.0%, Mg: 0 to 1.0%, Mn: 0 to 1.5%, Nb: 0 to 0.5%, Ni: 0 to 1.5%, P: 0 to 0.2%, S: 0 to 0.2%, Si: 0 to 1.0%, Sn: 0 to 1.5%, V: 0 to 1.0%, Zn: 0 to 2.0%, Zr: 0 to 1.0%, and among the above elements, Ag, B, Be, C The steel sheet has a composition in which the total content of Ti, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn, and Zr is 3.0% or less, the Ti / Al ratio is 1.50 or more, and the balance is Cu and unavoidable impurities, the tensile strength in the rolling direction is 1150 MPa or more, and in measurement of a measurement area provided on a cross section perpendicular to the rolling direction by EBSD (electron backscatter diffraction) with a step size of 0.02 μm, the average crystal grain size is 1.0 μm or less as determined by the Area Fraction method when boundaries with a crystal orientation difference of 5° or more are considered to be crystal grain boundaries, and the steel sheet has a crystal orientation in which the X-ray diffraction intensity ratio A expressed by the following formula (1) is 0.50 or more in the X-ray diffraction pattern of the sheet surface, and the number density of coarse precipitate particles with a major axis of 1.0 μm or more is 1.0 × 10 ５ pieces / mm ２ The following is a copper alloy sheet material. A=I{220} / (I{111}+I{200}+I{220}+I{311}+I{331}+I{420})...(1) Here, I{hkl} is the integrated intensity of the diffraction peak of the Cu parent phase {hkl} crystal plane.

5. The copper alloy sheet material according to any one of claims 1 to 4, further having a composition containing rare earth elements in a total amount of 3.0 mass% or less.

6. Density is 8.55 g / cm ３ The copper alloy sheet material according to any one of claims 1 to 4, wherein:

7. The copper alloy sheet material according to claim 6, further comprising rare earth elements in a total amount of 3.0 mass% or less.

8. The copper alloy sheet material according to any one of claims 1 to 4, having a sheet thickness of 0.015 to 0.15 mm.

9. The copper alloy sheet according to claim 8, further comprising rare earth elements in a total amount of 3.0 mass% or less.

10. In mass%, Ti: 2.0 to 5.0%, Al: 0.5 to 3.0%, Ag: 0 to 0.3%, B: 0 to 0.25%, Be: 0 to 0.2%, Co: 0 to 1.0%, Cr: 0 to 1.0%, Fe: 0 to 1.

0. %, Mg: 0-1.0%, Mn: 0-1.5%, Nb: 0-0.5%, Ni: 0-1.5%, P: 0-0.2%, S: 0-0.2%, Si: 0-1.0%, Sn: 0-1.5%, V: 0-1.0 %, Zn: 0 to 2.0%, Zr: 0 to 1.0%, and among the elements, the total content of Ag, B, Be, Co, Cr, Fe, Mg, Mn, Nb, Ni, P, S, Si, Sn, V, Zn and Zr is 3.0% or less, the Ti / Al ratio is 1.50 or more, and the balance is Cu and unavoidable impurities, and a tensile strength in the rolling direction is 1150 MPa or more, A process for producing a copper alloy sheet material by subjecting an intermediate product sheet material having the composition to solution treatment, aging treatment, finish cold rolling, and finish heat treatment in the aforementioned order, The solution treatment is carried out under the condition of maintaining the temperature in the range of 750 to 970°C, Aging treatment is carried out at an aging temperature of 300 to 520°C, Finish cold rolling is performed at a rolling ratio of 90% or more, The final heat treatment is carried out at a holding temperature T (°C) that satisfies the following formulas (2) to (4), for a reference time t ０ (seconds) and the allowable fluctuation time δ (seconds) expressed by the following formula (5-1) or (5-2): ０ ±δ (seconds) Manufacturing method of copper alloy sheet material. 280≦T≦520 ... (2) t ０ ≧30 …(3) t ０ =125×Ti+200×Al-1.15×T …(4) 30≦t ０ <100, δ = 10 ... (5-1) t ０ When ≧100, δ=0.1×t ０ …(5-2) Here, t ０ is the reference time (seconds), T is the holding temperature (°C) within the range of 280 to 520°C, and δ is the allowable fluctuation time (seconds). The element symbols Ti and Al in formula (4) are substituted with the values ​​of the Ti content (mass%) and Al content (mass%) of the sheet material, respectively.

11. 11. The method for producing a copper alloy sheet according to claim 10, further comprising the step of: adding rare earth elements in a total amount of 3.0 mass% or less; and wherein the intermediate product sheet has the composition.

12. A spring member made from the copper alloy sheet material according to any one of claims 1 to 4.

13. The spring member according to claim 12, wherein the spring member is made of a copper alloy sheet having a composition further containing rare earth elements in a total amount of 3.0 mass % or less.

14. A spring member for an autofocus camera module, which uses the copper alloy sheet material according to any one of claims 1 to 4 as its material.

15. 15. The spring member for an autofocus camera module according to claim 14, wherein the spring member is made of a copper alloy sheet having a composition further containing rare earth elements in a total amount of 3.0 mass % or less.

16. An autofocus camera module comprising a lens, a driving force imparting means for driving the lens in an optical axis direction, and a spring member for urging the lens to a reference position in the optical axis direction, wherein the copper alloy sheet material according to any one of claims 1 to 4 is used as a material for the spring member.

17. 17. The autofocus camera module according to claim 16, wherein the spring member is made of a copper alloy sheet having a composition further containing rare earth elements in a total amount of 3.0 mass % or less.

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