Copper alloy sheet material and its manufacturing method

Abstract

To provide a copper alloy plate having high conductivity and high tensile strength and excellent also in wet etching processability, even when an addition amount of Ag is scarce and its manufacturing method.SOLUTION: A copper alloy sheet material 10 has an alloy composition containing Ag in a range of 1.0 mass% or more and 4.0 mass% or less, the balance being Cu and inevitable impurities, and has a dual phase structure containing a first phase 11 which is a Cu mother phase and the second phase which is a plurality of Ag phases extending along a rolling direction x at intervals, wherein when viewed in a vertical cross-section containing a rolling direction x and a plate thickness direction y, among the two phases, the second phase having a length of 1 μm or more when measured along the rolling direction x is defined as the specific second phase 12, and when a phase interval d between specific second phases 12 adjacent along the plate thickness direction y is measured, an average phase interval that is an average value of the phase interval d is in the range of 10 nm or more and 200 nm or less, and the number of the phase intervals d that become 10 times or more the average phase interval is 1.0% or less by a ratio occupying in the total number of the measured phase intervals d.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a copper alloy sheet material and a method for producing the same, and more particularly to a copper alloy sheet material suitable for use in lead frames, connectors, terminal materials, etc. for electric and electronic devices and in-vehicle parts, and a method for producing the same. [Background technology]

[0002] Conventionally, Cu-Ni-Si alloys (Corson alloys), which are high-strength copper alloys strengthened mainly by precipitation strengthening and work hardening, have been widely used as copper alloy sheet materials, for example, for use in electrical and electronic components and automotive components.

[0003] However, Cu-Ni-Si alloys have a maximum electrical conductivity of about 50% IACS, and when a large current is passed through them, the amount of heat generated by resistance increases. This heat can reduce the springiness of the contact points and deteriorate the mold that secures the terminals, which can significantly reduce the functionality of the terminals, making them unsuitable for use as terminal materials for large currents.

[0004] For this reason, there is a demand for the development of terminal materials that can replace Cu-Ni-Si alloys. For example, alloys with a multi-phase structure in which a second phase containing other elements is crystallized in a Cu matrix (multi-phase alloys) can be produced by performing severe cold rolling after heat treatment, which disperses the second phase into fibers, giving them strength equivalent to that of phosphor bronze, and because the matrix is ​​Cu, they also have high electrical conductivity. Known examples of this multi-phase alloy system include Cu-Cr, Cu-Fe, Cu-Nb, Cu-Ag, and Cu-Zr.

[0005] For example, Patent Document 1 describes a copper alloy containing Cr in the range of 5% by weight or more and 30% by weight or less, and one or two of Zr and Ti in the range of 0.05% by weight or more and 0.5% by weight or less in total, with the remainder being Cu and unavoidable impurities, and claims that by setting the thickness of the Cu matrix separated by fibrous Cr phases to 5 μm or less, a copper alloy material having excellent tensile strength and electrical conductivity can be obtained.

[0006] Furthermore, Patent Document 2 discloses that in a copper alloy containing one or more elements selected from the group consisting of Cr, Fe, and Nb in a total range of 7% by mass to 20% by mass, or containing 7% by mass to 20% by mass of Ag, with the balance being Cu and unavoidable impurities, by setting the average aspect ratio (At) of the second phase containing one or more elements selected from the group consisting of Cr, Fe, and Nb, or containing 60% or more of Ag, in the range of 10 to 80, as viewed in a cross section perpendicular to the rolling direction, excellent strength, electrical conductivity, and bending workability can be obtained, and anisotropy of strength and bending workability can be suppressed.

[0007] Furthermore, Patent Document 3 describes a copper alloy containing Zr in the range of 3.0 atomic % to 7.0 atomic % both inclusive, with the remainder being Cu and unavoidable impurities, in which a Cu matrix and a composite phase consisting of a Cu-Zr compound phase and a copper phase form a matrix-composite phase lamellar structure, and when viewed in a cross section perpendicular to the width direction, the Cu matrix and the composite phase are alternately arranged parallel to the rolling direction, and the copper-Zr compound phase and the copper phase arranged in the rolling direction are alternately stacked in the sheet thickness direction with a phase thickness of 50 nm or less, thereby achieving a higher tensile strength.

[0008] Furthermore, Patent Document 4 describes that in a copper alloy containing Ag in the range of 7% by mass or more and 15% by mass or less, and containing one or more trace elements selected from the group consisting of Cr, Fe, Nb, Co, Ni, Mg, Sn, Zr, Cd, Ti, P, In, and Si in a total range of 0.05% by mass or more and 1% by mass or less, with the remainder being Cu and unavoidable impurities, by setting the average aspect ratio (At) of the second phase containing Ag in the range of 10 or more and 80 or less when viewed in a cross section perpendicular to the rolling direction, excellent tensile strength (0.2% proof stress) can be obtained.

[0009] Furthermore, Patent Document 5 describes that in a copper alloy thin wire containing Ag in the range of 2 mass % to 10 mass % and the remainder being Cu and unavoidable impurities, the entire structure of the Cu solid solution is made up of a recrystallized texture, and therefore, a copper alloy thin wire having excellent tensile strength can be obtained.

[0010] Patent Document 6 also describes that in a copper alloy wire containing Ag in the range of 0.5% by mass to 6.0% by mass, one or more selected from the group consisting of Mg, Cr, and Zr in a total amount of 0.01% by mass to 1.5% by mass, with the remainder being Cu and unavoidable impurities, by setting the average nearest-neighbor spacing of second-phase particles having a particle size of 200 nm or less to 580 nm or less when viewed in a cross section perpendicular to the longitudinal direction, excellent tensile strength (0.2% proof stress), flexibility, electrical conductivity, and vibration durability can be obtained. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Patent No. 3490853 [Patent Document 2] Patent No. 4302579 [Patent Document 3] Patent No. 5800301 [Patent Document 4] Patent No. 5048046 [Patent Document 5] Patent No. 5051647 [Patent Document 6] Patent No. 6407484 Summary of the Invention [Problem to be solved by the invention]

[0012] Copper alloys for electronic materials, such as lead frames, connectors, and terminal materials for electrical and electronic devices and automotive components, are required to have excellent mechanical strength and electrical conductivity, as well as good wet-etching processability, in order to meet the demands of increasingly complex component shapes and improved reliability in assembly and packaging. In particular, wet-etching processability requires uniform etching of the etched surface, even when second phases such as precipitates or crystallized particles are present on the etched surface, resulting in minimal protrusions on the etched surface (e.g., the end face of a lead) after wet etching. However, when conventional rolled materials such as plate materials are wet-etched for thickness reduction, coarse precipitates or crystal grains of the parent phase remain after wet etching, or the precipitate distribution becomes uneven, resulting in surface roughness greater than before wet etching. In this regard, Patent Documents 1 to 6 make no mention of protrusions on the end face of a lead after wet etching, let alone wet-etching processability.

[0013] Furthermore, the copper alloys described in Patent Documents 1 to 4 contain elements such as Cr, Fe, Nb, Ag, and Zr in amounts significantly exceeding their solid solubility limits in the Cu matrix to increase tensile strength by densely dispersing second phases containing these elements in the Cu matrix. They also require high-processing rates, such as wiredrawing and lap-roll bonding (ARB). Elements such as Nb, Ag, and Zr are significantly more expensive than Cu, and increasing their content significantly increases raw material costs. Furthermore, copper alloys containing large amounts of elements such as Cr, Fe, Nb, Ag, and Zr tend to have reduced electrical conductivity. Therefore, there has been a demand for copper alloys that have high electrical conductivity and high tensile strength, even when containing only small amounts of additional elements such as Ag.

[0014] Furthermore, the copper alloys described in Patent Documents 5 and 6 are subjected to a large degree of working by obtaining wire rods through wire drawing during cold working, and no description is given of a method for obtaining foils or plates through rolling.

[0015] Among these, the copper alloy thin wire described in Patent Document 5 is subjected to a recrystallization heat treatment after cold wiredrawing to maximize the precipitation of Ag solid-solved in the matrix, and then the Ag is drawn out by a high degree of cold wiredrawing, thereby achieving high strength. However, it is known that in Cu-Ag alloys, Ag precipitates discontinuously in the Cu matrix and disperses unevenly. In particular, when the amount of Ag added is small, the distribution of precipitated Ag becomes more uneven, which in turn results in a more uneven distribution of Ag fibers after wiredrawing. In this regard, the copper alloy thin wire described in Patent Document 5 has not been examined at all for the distribution of Ag precipitated by heat treatment or the distribution of Ag fibers after wiredrawing.

[0016] Furthermore, in the copper alloy wire described in Patent Document 6, Ag is precipitated by casting, then the wire is drawn, and then a final heat treatment is performed, thereby obtaining a copper alloy wire with a controlled density distribution of the Ag phase, which is said to have excellent tensile strength, flexibility, electrical conductivity, and vibration durability.However, since the copper alloy wire is softened by the final heat treatment, there is room for improvement in terms of tensile strength.

[0017] Therefore, an object of the present invention is to provide a copper alloy sheet material that has high electrical conductivity and high tensile strength and also has excellent wet etching workability even when the amount of Ag added is small, and a method for producing the same. [Means for solving the problem]

[0018] The present inventors have found that by observing a longitudinal cross section of a rolled copper alloy sheet, including the rolling direction and the thickness direction, which has been smoothed by electrolytic polishing, with a transmission electron microscope (TEM), it is possible to clearly observe the structure of a second phase, which has not been clearly observable in the past. The present inventors have also found that by subjecting a copper alloy material to a hot rolling process, followed by heat treatment and rolling under specific conditions in the following order: a first cold rolling process, a solution treatment process, a second cold rolling process, an aging heat treatment process, and a third cold rolling process, the second phase (the white striped portion in the photograph of FIG. 1) having a length of 1 μm or more extends fibrously in the rolling direction when viewed in a longitudinal cross section including the rolling direction and the thickness direction, as shown in FIG. 1, and the number of locations where the spacing between the second phases is widened is relatively small, thereby not only obtaining high tensile strength but also improving wet etching processability, even with a small amount of Ag added. As a result, they found that even with a small amount of Ag added, it is possible to obtain a copper alloy sheet material that has high electrical conductivity, high tensile strength, and excellent wet etching workability, and they have completed the present invention.

[0019] In order to achieve the above object, the gist of the present invention is as follows. (1) A copper alloy sheet having an alloy composition containing 1.0 mass% or more and 4.0 mass% or less of Ag, with the remainder being Cu and unavoidable impurities, and having a multi-phase structure including a first phase which is a Cu matrix phase and a second phase which is a plurality of Ag phases extending at intervals along the rolling direction, wherein, when viewed in a longitudinal section including the rolling direction and the thickness direction of the copper alloy sheet, among the second phases, a second phase having a length of 1 μm or more when measured along the rolling direction is defined as a specific second phase, and when the phase spacing between adjacent specific second phases is measured along the thickness direction of the copper alloy sheet, the average phase spacing, which is the average value of the phase spacings, is in the range of 10 nm or more and 200 nm or less, and the proportion of the number of phase spacings which are 10 times or more the average phase spacing to the total number of measured phase spacings is 1.0% or less. (2) In the crystal orientation analysis performed by measuring the longitudinal section using the EBSD method, {011} <100> Goss direction of {011} <211> Brass orientation and {123} <634> the total area, calculated by adding up the areas of the crystal grains oriented in the Goss orientation, the Brass orientation, and the S orientation, accounts for 30% or less of the total area of ​​all the crystal grains; and the crystal grains oriented in the Goss orientation, the Brass orientation, and the S orientation all have an average aspect ratio, which is the average value of the aspect ratios of the crystal grains, of 5 or more and 100 or less. (3) The copper alloy sheet material according to (1) or (2) above, wherein the alloy composition further contains at least one optional additive component selected from the group consisting of 0.05% by mass or more and 1.0% by mass or less of Cr, 0.05% by mass or more and 1.0% by mass or less of Zr, 0.05% by mass or more and 1.0% by mass or less of Fe, 0.05% by mass or more and 0.5% by mass or less of Mg, and 0.05% by mass or more and 1.0% by mass or less of Zn, in an amount of 0.05% by mass or more and 1.0% by mass or less. (4) The copper alloy sheet material according to any one of (1) to (3) above, having a sheet thickness in the range of 0.03 mm or more and 0.20 mm or less. (5) A method for producing a copper alloy sheet material according to any one of (1) to (4) above, comprising the steps of: casting a copper alloy material having the alloy composition (step 1), homogenizing heat treatment (step 2), hot rolling (step 3), water cooling (step 4), facing (step 5), first cold rolling (step 6), solution treatment (step 7), second cold rolling (step 8), aging heat treatment (step 9), and third cold rolling (step 10) in that order; in the casting (step 1), the copper alloy material is melted to produce an ingot; and in the hot rolling (step 3), the rolling temperature in the final pass is set to 700°C or more and 800°C or less, and the rolling temperature in the final pass is set to 100°C or more. a working ratio of 20% or more; a total working ratio of 70% or more and 95% or less in the first cold rolling step [step 6]; a final temperature of 550°C or more and 750°C or less and a holding time of 0.1 hour or more and 10 hours or less in the solution treatment step [step 7]; a total working ratio of 20% or more and 80% or less in the second cold rolling step [step 8]; a final temperature of 325°C or more and 500°C or less and a holding time of 0.1 hour or more and 100.0 hours or less in the aging heat treatment step [step 9]; and a total working ratio of 95.0% or more and 99.0% or less in the third cold rolling step [step 10]. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a copper alloy sheet material that has high electrical conductivity and high tensile strength and also has excellent wet etching workability even when the amount of Ag added is small, and a method for producing the same. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a transmission electron microscope (TEM) photograph of a copper alloy sheet material of the present invention, viewed in a longitudinal section including the rolling direction and the thickness direction. [Figure 2] FIG. 1 is a schematic diagram for explaining a method for determining the phase spacing between adjacent specific second phases from a transmission electron microscope (TEM) photograph of a plurality of specific second phases contained in the copper alloy material of the present invention viewed in a vertical cross section including the rolling direction of the copper alloy material. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, preferred embodiments of the copper alloy sheet material of the present invention will be described in detail.

[0023] The copper alloy sheet according to the present invention has an alloy composition containing 1.0 mass % or more and 4.0 mass % or less of Ag, with the remainder being Cu and unavoidable impurities, and has a multi-phase structure including a first phase which is a Cu matrix and a second phase which is a plurality of Ag phases extending at intervals along the rolling direction, wherein, when viewed in a longitudinal cross section including the rolling direction and the thickness direction of the copper alloy sheet, among the second phases, a second phase having a length of 1 μm or more when measured along the rolling direction is defined as a specific second phase, and when the phase spacing between adjacent specific second phases is measured along the thickness direction of the copper alloy sheet, the average phase spacing, which is the average value of the phase spacings, is in the range of 10 nm or more and 200 nm or less, and the proportion of the number of phase spacings which are 10 times or more the average phase spacing to the total number of measured phase spacings is 1.0% or less.

[0024] As shown in Fig. 1, when viewed in a longitudinal cross section including the rolling direction and the sheet thickness direction, among the second phases (white striped portions in the photograph of Fig. 1) extending fibrously at intervals along the rolling direction, specific second phases having lengths of 1 µm or more when measured along the rolling direction are included, and the number of locations where the phase spacing between adjacent specific second phases is wide is relatively small. This not only enables high tensile strength to be obtained even with a small amount of Ag added, but also improves wet etching workability. Furthermore, by adding Ag in an amount ranging from 1.0% by mass to 4.0% by mass, a decrease in electrical conductivity due to excessive addition of Ag is unlikely to occur. As a result, by using the copper alloy sheet according to the present invention, it is possible to obtain a copper alloy sheet having high electrical conductivity, high tensile strength, and excellent wet etching workability, even with a small amount of Ag added.

[0025] Furthermore, in the crystal orientation analysis performed by measuring the longitudinal section of the copper alloy sheet, which is a rolled material, by the electron backscatter diffraction method (EBSD method), the area ratio and average aspect ratio of crystal grains oriented in a specific orientation are within a predetermined range, so that the tensile strength and wet etching workability can be further improved.

[0026] In addition, the copper alloys described in Patent Documents 1 to 4 contain an amount of elements that significantly exceeds the solid solubility limit in the Cu matrix in order to densely disperse the second phase containing elements such as Cr, Fe, Nb, Ag, and Zr in the Cu matrix, and it is necessary to perform cold working with a high working ratio such as wire drawing or accumulative roll bonding method (ARB method). Here, since elements such as Nb and Ag are extremely expensive compared to Cu, the raw material cost significantly increases as the content increases. Also, when a large amount of elements with high melting points such as Cr, Fe, Nb, and Zr are contained, the molten metal temperature required during casting becomes very high (above 1400 °C depending on the composition), and it becomes difficult to manufacture with general copper alloy casting equipment (1100 - 1400 °C), resulting in high manufacturing costs. Regarding this, in the copper alloy sheet of the present invention, since the content of Cr, Fe, Nb, Ag, Zr, which are components contained in the second phase, can be reduced, it is also possible to obtain an excellent copper alloy sheet from the viewpoints of raw material cost and manufacturing cost.

[0027] [1] Composition of Copper Alloy Sheet First, the reasons for limiting the alloy composition of the copper alloy sheet of the present invention will be explained. The copper alloy sheet of the present invention has an alloy composition containing Ag in the range of 1.0 mass% or more and 4.0 mass% or less.

[0028] <Ag: 1.0 mass% or more and 4.0 mass% or less> Ag (silver) is a single Ag phase that does not dissolve in the first phase, the Cu matrix, and is finely precipitated in the form of precipitates, for example, approximately 1 to 100 nm in size. These precipitates are elongated and fiberized in the rolling direction by rolling, forming a multi-phase structure containing an Ag phase as a specific second phase, thereby improving the tensile strength of the multi-phase alloy. To achieve this effect, the Ag content must be 1.0 mass% or more. On the other hand, an Ag content exceeding 4.0 mass% leads to an increase in raw material costs. Therefore, in the present invention, the Ag content is limited to 4.0 mass% or less. Furthermore, an Ag content exceeding 4.0 mass% is undesirable because the second phase, which is an Ag phase with different etching processability from the first phase, becomes coarse or the number of second phases increases, thereby deteriorating wet etching processability. Therefore, the Ag content is in the range of 1.0 mass% to 4.0 mass%, preferably 1.8 mass% to 3.8 mass%.

[0029] <Optional addition ingredients> The copper alloy sheet of the present invention may contain components other than Ag as optional additives. More specifically, the alloy composition of the copper alloy sheet may further contain at least one optional additive selected from the group consisting of 0.05% by mass to 1.0% by mass of Cr, 0.05% by mass to 1.0% by mass of Zr, 0.05% by mass to 1.0% by mass of Fe, 0.05% by mass to 0.5% by mass of Mg, and 0.05% by mass to 1.0% by mass of Zn, in a total amount of 0.05% by mass to 1.0% by mass.

[0030] (Cr: 0.05 mass% or more and 1.0 mass% or less) Cr (chromium) is a component that precipitates finely in the first phase, which is the Cu matrix, as a compound or as an element, in the form of precipitates with a size of, for example, about 50 nm to 500 nm. The fine precipitates inhibit dislocation movement during aging heat treatment, thereby promoting hardening of the copper alloy sheet, and inhibit grain growth to promote the precipitation of fine crystals. This component therefore has the effect of improving the tensile strength and bending workability of the copper alloy sheet. To achieve this effect, the Cr content is preferably 0.05% by mass or more. On the other hand, by limiting the Cr content to 1.0% by mass or less, the electrical conductivity of the copper alloy sheet is less likely to decrease, making it easier to achieve a desired high electrical conductivity. Therefore, the Cr content is preferably in the range of 0.05% by mass to 1.0% by mass, and more preferably in the range of 0.1% by mass to 0.5% by mass.

[0031] (Zr: 0.05 mass% or more and 1.0 mass% or less) Zr (zirconium) is a component that mainly functions to refine crystal grains and improve the tensile strength and bending workability of copper alloy sheets. To achieve this function, the Zr content is preferably 0.05% by mass or more. On the other hand, if the Zr content is greater than 1.0% by mass, Zr forms a compound with Ag, reducing the number of Ag phases, which in turn reduces the number of specific second phases, tending to reduce the tensile strength of the copper alloy sheets. For this reason, the Zr content is preferably in the range of 0.05% by mass to 1.0% by mass, more preferably in the range of 0.1% by mass to 0.5% by mass.

[0032] (Fe: 0.05 mass% or more and 1.0 mass% or less) Iron (Fe) is a component that increases the electrical conductivity and tensile strength of copper alloy sheets and improves properties such as stress relaxation resistance and plating ability. To achieve this effect, the Fe content is preferably 0.05% by mass or more. On the other hand, by setting the Fe content to 1.0% by mass or less, the electrical conductivity is less likely to decrease, making it easier to obtain a desired high electrical conductivity. For this reason, the Fe content is preferably in the range of 0.05% by mass or more and 1.0% by mass or less, and more preferably in the range of 0.1% by mass or more and 0.5% by mass or less.

[0033] (Mg: 0.05 mass% or more and 0.5 mass% or less) Magnesium (Mg) is a component that improves the stress relaxation resistance of copper alloy sheets. To achieve this effect, the Mg content is preferably 0.05% by mass or more. Furthermore, by setting the Mg content to 0.5% by mass or less, the electrical conductivity is less likely to decrease, making it easier to obtain a desired high electrical conductivity. For this reason, the Mg content is preferably set in the range of 0.05% by mass or more and 0.5% by mass or less.

[0034] (Zn: 0.05 mass% or more and 1.0 mass% or less) Zn (zinc) is a component that improves the bending workability of copper alloy sheets and also improves the adhesion and migration properties of Sn plating and solder plating. To achieve this effect, the Zn content is preferably 0.05% by mass or more. On the other hand, by keeping the Zn content at 1.0% by mass or less, the electrical conductivity is less likely to decrease, making it easier to obtain a desired high electrical conductivity. Therefore, the Zn content is preferably in the range of 0.05% by mass or more and 1.0% by mass or less.

[0035] (At least one optional added component selected from the group consisting of Cr, Zr, Fe, Mg, and Zn: 0.05% by mass or more and 1.0% by mass or less in total) When at least one component selected from the group consisting of Cr, Zr, Fe, Mg, and Zn is contained as an optional component other than Ag, the total content of these optional components is preferably 0.05% by mass or more and 1.0% by mass or less. Here, by containing these optional components in a total content of 0.05% by mass or more, the tensile strength, stress relaxation property, heat resistance, etc. of the copper alloy sheet can be improved. On the other hand, by containing these optional components in a total content of 1.0% by mass or less, the decrease in electrical conductivity of the copper alloy sheet can be minimized. Therefore, the total content of these optional components is preferably 0.05% by mass or more and 1.0% by mass or less, and more preferably 0.05% by mass or more and 0.5% by mass or less.

[0036] <Remainder: Cu and unavoidable impurities> The copper alloy sheet material 10 of the present invention has an alloy composition consisting of the above-mentioned components, with the remainder being Cu (copper) and inevitable impurities. The term "unavoidable impurities" as used herein generally refers to impurities present in the raw materials of metal products or unavoidably mixed in during the manufacturing process. These impurities are essentially unnecessary but are tolerated in trace amounts because they do not affect the properties of the metal product. Examples of inevitable impurities include tin (Sn) and oxygen (O). The upper limit of the content of these components can be, for example, 0.05% by mass for each of the above components, or 0.20% by mass for the total amount of the above components.

[0037] [2] Metal structure of copper alloy sheet Fig. 1 is a transmission electron microscope (TEM) photograph of a copper alloy sheet 10 of the present invention, taken in a longitudinal section including the rolling direction x and the sheet thickness direction y. Fig. 2 is a schematic diagram for explaining a method for determining the phase spacing d between adjacent specific second phases 12a, 12b from a transmission electron microscope (TEM) photograph of a plurality of specific second phases 12a, 12b contained in the copper alloy sheet 10 of the present invention, taken in a longitudinal section including the rolling direction x and the sheet thickness direction y of the copper alloy sheet 10.

[0038] The copper alloy sheet 10 of the present invention has a multi-phase structure including a first phase 11, which is a Cu matrix phase, and a second phase, which is a plurality of Ag phases extending at intervals along the rolling direction x. Here, Ag constituting the second phase is finely precipitated as a single Ag phase that is not solid-dissolved in the Cu matrix phase, for example, in the form of precipitates having a size of about 1 to 100 nm, so that the metal structure of the copper alloy sheet 10 is a multi-phase structure in which the second phase composed of Ag phases is precipitated in the first phase 11, which is a Cu matrix phase.

[0039] Furthermore, in the copper alloy sheet 10 of the present invention, when viewed in a longitudinal section including the rolling direction x and the sheet thickness direction y, among the multiple second phases, second phases having a total length L of 1 μm or more as measured along the rolling direction x are designated as specific second phases 12a, 12b. When the phase spacing d between adjacent specific second phases 12a, 12b is measured along the sheet thickness direction y of the copper alloy sheet 10, the average phase spacing, which is the average value of the measured phase spacings d, is in the range of 10 nm to 200 nm (requirement (I)). Here, by making the average phase spacing 10 nm or more, a decrease in electrical conductivity due to the accumulation of dislocations caused by cold rolling is less likely to occur, and a desired high electrical conductivity can be obtained. Therefore, the average phase spacing, which is the average value of the measured phase spacings d, is 10 nm or more, preferably 15 nm or more. On the other hand, by making the average phase spacing 200 nm or less, the specific second phases 12 are densely formed, which improves the tensile strength due to cold rolling, and therefore a desired high tensile strength can be obtained. Therefore, the average interphase spacing, which is the average value of the interphase spacings d measured, is 200 nm or less, and preferably 100 nm or less.

[0040] The average interphase spacing, which is the average value of the interphase spacings d between adjacent specific second phases 12a, 12b, which is the requirement (I), can be determined, for example, by using a transmission electron microscope (TEM). In this case, a longitudinal section of the copper alloy sheet 10, including the rolling direction x and the sheet thickness direction y, is wet-polished, and then a partial region (for example, a region of 40 μm in the rolling direction × 15 μm in the sheet thickness direction) is micro-sampled by a focused ion beam (FIB), and a TEM sample is prepared by thinning and Ar ion milling, and one or more portions of the sample are observed by a transmission electron microscope (TEM). For the obtained TEM image, ten lines (perpendicular lines E) each 5 μm long are drawn along the thickness direction y at intervals of 5 μm in the rolling direction x, and the number of specific second phases 12 that cross the perpendicular lines E is counted. The sum of the lengths of the perpendicular lines E drawn along the thickness direction y is then divided by the total number of specific second phases 12 that cross each line segment plus 1, thereby allowing the average phase spacing of the specific second phases 12 along the thickness direction y to be calculated.

[0041] Furthermore, in the copper alloy sheet 10 of the present invention, when viewed in a longitudinal section including the rolling direction x and the sheet thickness direction y, the number of phase spacings d that are 10 times or more the average phase spacing accounts for 1.0% or less of the total number of measured phase spacings d (requirement (II)). Here, even if the requirement (I) regarding the average phase spacing is satisfied, if the number of phase spacings d that are 10 times or more the average phase spacing is large, it becomes difficult to increase the tensile strength even by cold rolling, and the surface roughness of the copper alloy sheet 10 is likely to increase by wet etching. This is thought to be because when regions with large phase spacings d occur, dislocation pinning due to cold working is reduced, thereby reducing tensile strength, and when the phase spacings d are non-uniform, the etching rate during wet etching varies depending on the location, thereby increasing surface roughness. Therefore, from the viewpoint of increasing the tensile strength and wet etching processability of the copper alloy sheet material 10, the number of phase spacings d that are 10 times or more the average phase spacing when viewed in a longitudinal section is 1.0% or less of the total number of measured phase spacings d, and preferably 0.8% or less.

[0042] The ratio of the number of phase spacings d that are 10 times or more the average phase spacing, which is requirement (II), to the total number of measured phase spacings d can be calculated by dividing the number of phase spacings that are 10 times or more the average phase spacing, which is obtained by measuring the phase spacings d between the specific second phases 12a, 12b that are adjacent to each other along the thickness direction y and cross the line segment (perpendicular line E) from the above-mentioned TEM image, by the total number of phase spacings d, and then multiplying the result by 100.

[0043] In addition, when the value of the average phase spacing of requirement (I) is large, the proportion of phase spacings d having a value equal to or greater than a certain value inevitably tends to be large. Therefore, in the present invention, the proportion of phase spacings d whose multiplication factor with respect to the average phase spacing is equal to or greater than a certain value, rather than the absolute value of the phase spacing d, is set as requirement (II).

[0044] In the copper alloy sheet material 10 of the present invention, a crystal orientation analysis was performed by measuring a longitudinal section including the rolling direction x and the sheet thickness direction y by electron backscatter diffraction (EBSD) method, and it was found that the {011} <100> Goss direction of {011} <211> Brass orientation and {123} <634> It is preferable that the ratio of the total area of ​​the crystal grains, calculated by adding up the areas of the crystal grains oriented in the S-orientation of each of the above, to the total area of ​​all the crystal grains, is 30% or less (requirement (III)). As a result, the ratio of these crystal orientations, which are typical crystal orientations of copper alloys, to the crystal phases exposed in the longitudinal cross section of the copper alloy sheet 10 is reduced, and the crystal orientations of the exposed crystal phases become nearly random, so that crystal phases with various crystal orientations and different etching rates are exposed in a balanced manner. As a result, the surface roughness (particularly the arithmetic mean roughness (Ra)) of the surface of the copper alloy sheet 10 after wet etching can be reduced.

[0045] The ratio of the total area of ​​the Goss orientation, the Brass orientation, and the S orientation to the total area of ​​the entire crystal grain, which is requirement (III), can be determined by, for example, performing crystal orientation analysis by electron backscatter diffraction (EBSD) using a scanning electron microscope (SEM). In this case, crystal orientation analysis can be performed using EBSD on a region observed using a scanning electron microscope (SEM) of a sample prepared by mechanically polishing and finish-polishing a longitudinal section of the copper alloy sheet material 10. Then, from the results of the crystal orientation analysis of the above region, the {011} <100> Goss direction of {011} <211> Brass orientation and {123} <634> The ratio of the total area of ​​the Goss orientation, Brass orientation, and S orientation to the total area of ​​all crystal grains can be calculated by adding up the areas of the crystal grains oriented in each of the S orientations and dividing the total area by the area of ​​the above region.

[0046] In addition, in the copper alloy sheet material 10 of the present invention, a crystal orientation analysis was performed by measuring a longitudinal section including the rolling direction x and the sheet thickness direction y by electron backscatter diffraction (EBSD) method, and it was found that the {011} <100> Goss direction of {011} <211> Brass orientation and {123} <634> It is preferable that the average aspect ratio, which is the average value of the aspect ratios of the crystal grains oriented in the S orientation, is 5 or more and 100 or less (requirement (IV)). In particular, by making the average aspect ratio of these crystal grains 5 or more, it is thought that the variation in etching rate due to the crystal grains oriented in these orientations is suppressed, and the surface roughness after etching can be reduced. Therefore, the average aspect ratio of the crystal grains oriented in the Goss orientation, Brass orientation, and S orientation is preferably 5 or more, and more preferably 10 or more. On the other hand, the upper limit of the average aspect ratio of the crystal grains oriented in the Goss orientation, Brass orientation, and S orientation is not particularly limited, but it may be set to 100 or less from the viewpoint of feasibility.

[0047] The average aspect ratio of the crystal grains oriented in the Goss, Brass and S orientations, which is requirement (IV), is determined as follows from the results of the crystal orientation analysis using the EBSD method described above: <100> Goss direction of {011} <211> Brass orientation and {123} <634> The aspect ratio (a / b) is the ratio of the maximum length of the crystal grain (a) along the rolling direction x to the maximum length of the crystal grain (b) along the thickness direction y, and is calculated for each of the crystal grains oriented in the S direction.

[0048] The copper alloy sheet material 10 of the present invention may contain a second phase that does not fall under the specific second phase 12, that is, a second phase whose total length L measured along the rolling direction x is less than 1 μm.

[0049] The thickness of the copper alloy sheet 10 of the present invention is not particularly limited, but is preferably in the range of 0.03 mm or more and 0.20 mm or less. In particular, from the viewpoint of not increasing the rolling processing rate more than necessary when producing the copper alloy sheet 10, the thickness of the copper alloy sheet 10 is preferably 0.03 mm or more. Furthermore, from the viewpoint of reducing the thickness of the ingot to facilitate hot rolling, the thickness of the copper alloy sheet 10 is preferably 0.20 mm or less.

[0050] [3] Tensile strength The copper alloy sheet 10 of the present invention preferably has a tensile strength of 700 MPa or more, more preferably 750 MPa or more, even more preferably 800 MPa or more, and even more preferably 900 MPa or more, when pulled in a direction parallel to the rolling direction x. This ensures that the desired spring properties are obtained, even when the copper alloy sheet 10 is used for applications such as disc springs and connectors, and high connectivity with connected electrical devices can be achieved. Here, the tensile strength is measured using three test pieces of type 13B as specified in JIS Z2241:2011, cut out so that the longitudinal direction is parallel to the rolling direction x. The average tensile strength value obtained from the three test pieces is taken as the measured tensile strength.

[0051] [4] Electrical conductivity (EC) The copper alloy sheet material 10 of the present invention preferably has an electrical conductivity of more than 70% IACS. This allows the copper alloy material to reduce heat generation during current flow even when used in applications such as high-current connectors. Here, the electrical conductivity can be calculated from the resistivity measured by a four-terminal method in a thermostatic chamber maintained at 20°C (±0.5°C).

[0052] [5] Wet etching processability The copper alloy sheet 10 of the present invention preferably has high wet etching workability. More specifically, when the copper alloy sheet 10 is wet etched using a ferric chloride (FeCl3) aqueous solution along the thickness direction y to a thickness of 10 μm, the arithmetic mean roughness (Ra) of the cross section perpendicular to the rolling direction x is preferably 0.4 μm or less, and the maximum height (Ry) of this cross section is preferably 1.8 μm or less. This allows the surface of the copper alloy sheet 10 to be flat even when formed by wet etching. This allows for high electrical connectivity to connected electrical devices and the like in applications such as lead frames, connectors, and terminal materials for electrical and electronic devices and automotive components. Furthermore, when the copper alloy sheet 10 is plated, peeling, swelling, protrusions, stains, and the like of the plating can be made less likely to occur. Furthermore, when the copper alloy sheet 10 is bent, cracks can be made less likely to occur. Therefore, it is more preferable that the arithmetic mean roughness (Ra) in the cross section is 0.4 μm or less. It is also more preferable that the maximum height (Ry) in the cross section is 1.5 μm or less. Here, the arithmetic mean roughness (Ra) and maximum height (Ry) are measured in accordance with JIS-B0601 (2001), and the average values ​​measured at three different locations are used as the measured values ​​of the arithmetic mean roughness (Ra) and maximum height (Ry).

[0053] [6] An example of a manufacturing method for copper alloy sheet materials The above-mentioned copper alloy sheet material can be realized by controlling the alloy composition and the manufacturing process in combination, and the manufacturing process is not particularly limited. Among them, the following method can be mentioned as an example of a manufacturing process that can generate such a multi-phase structure.

[0054] In one example of a method for producing a copper alloy sheet according to the present invention, a copper alloy material having substantially the same alloy composition as that of the copper alloy sheet described above is sequentially subjected to at least the following steps: casting (step 1), homogenization heat treatment (step 2), hot rolling (step 3), water cooling (step 4), facing (step 5), first cold rolling (step 6), solution treatment (step 7), second cold rolling (step 8), aging heat treatment (step 9), and third cold rolling (step 10). In the casting (step 1), the copper alloy material is melted to produce an ingot. In the hot rolling (step 3), the rolling temperature in the final pass is set to 700°C or higher and 800°C or lower, and the rolling reduction ratio in the final pass is set to 20% or higher. In the first cold rolling (step 6), the total reduction ratio is set to 70% or higher and 95% or lower. In the solution treatment process [Step 7], the ultimate temperature is set to a range of 550°C to 750°C and the holding time is set to a range of 0.1 to 10 hours. In the second cold rolling process [Step 8], the total working ratio is set to a range of 20% to 80%. In the aging heat treatment process [Step 9], the ultimate temperature is set to a range of 325°C to 500°C and the holding time is set to a range of 0.1 to 100.0 hours. In the third cold rolling process [Step 10], the total working ratio is set to a range of 95.0% to 99.0%.

[0055] (i) Casting process [Process 1] In the casting process [Step 1], a copper alloy material having the above-described alloy composition is melted and cast to produce an ingot of a predetermined shape (e.g., 300 mm thick, 500 mm wide, and 3000 mm long). In the casting process [Step 1], the copper alloy material is preferably melted and cast using a high-frequency melting furnace. Note that the alloy composition of the copper alloy material may not necessarily be completely identical to that of the copper alloy sheet material produced due to the addition of certain components that adhere to or volatilize in the melting furnace during each manufacturing process, but the copper alloy material has substantially the same alloy composition as that of the copper alloy sheet material.

[0056] In this casting step [Step 1], the molten copper alloy material is cast, whereby the second phase is crystallized in the ingot, and the growth of the crystallized second phase can be suppressed.

[0057] (ii) Homogenization heat treatment process [Process 2] The homogenization heat treatment step (step 2) is a step in which heat treatment is performed on the ingot after the casting step (step 1). The homogenization heat treatment step (step 2) is performed to homogenize the metal structure of the ingot and promote the formation of a fibrous second phase in a subsequent step. The conditions for the homogenization heat treatment are not particularly limited as long as they are commonly used conditions. An example of the conditions for the homogenization heat treatment is a holding temperature in the range of 800°C to 1000°C and a holding time in the range of 0.5 hours to 10 hours.

[0058] (iii) Hot rolling process [Process 3] The hot rolling process (Step 3) is a process in which the ingot that has undergone homogenization heat treatment is hot rolled to a predetermined thickness to produce a hot-rolled material. In the hot rolling process (Step 3), the rolling temperature in the final pass is set to 700°C or higher and 800°C or lower, and the rolling reduction rate in the final pass is set to 20% or higher.

[0059] In particular, if the rolling temperature of 700°C to 800°C and the rolling reduction ratio of 20% or more are not satisfied in the final pass of the hot rolling step [step 3], the grain size of the crystals becomes coarse after the hot rolling step [step 3], making it difficult to obtain a desired metal structure after the solution heat treatment step [step 7] and the aging heat treatment step [step 9] described below, and therefore making it difficult to uniformly disperse the second phase in the first phase 11 in the copper alloy sheet material 10. As a result, even after the cold rolling step described below is performed, the distribution of the second phase becomes non-uniform, making it difficult to obtain sufficient tensile strength and wet etching workability.

[0060] In the hot rolling step [step 3], the rolling temperature other than the final pass is preferably 700° C. or higher, and the total rolling processing rate (total processing rate) is preferably 90% or higher.

[0061] Here, the "rolling reduction rate" is a value obtained by subtracting the cross-sectional area after rolling from the cross-sectional area before rolling, dividing the value by the cross-sectional area before rolling, and multiplying the result by 100, expressed as a percentage, and is expressed by the following formula. [Rolling reduction rate] = {([Cross-sectional area before rolling] - [Cross-sectional area after rolling]) / [Cross-sectional area before rolling]} x 100 (%)

[0062] (iv) Water cooling process [Process 4] The water cooling step is a step of cooling the hot-rolled material by water after the hot rolling step [step 3]. By cooling the hot-rolled material by water, the hot-rolled material can be cooled at a high cooling rate of, for example, 50°C / second or more, which makes it difficult for the second phase to coarsen.

[0063] (v) Facing process [Process 5] The facing step [step 5] is a step of scraping off the surface of the hot-rolled material after the cooling step [step 4]. By performing the facing step, it is possible to remove the oxide film and defects on the surface that occurred in the hot-rolling step [step 3]. The conditions for the facing step are not particularly limited as long as they are commonly used conditions. The amount of material scraped off from the surface of the hot-rolled material can be adjusted appropriately based on the conditions of the hot-rolling step [step 3], and can be, for example, about 0.5 mm to 4 mm from the surface of the hot-rolled material.

[0064] (vi) First cold rolling process [Process 6] The first cold rolling process [Step 6] involves cold rolling the hot-rolled material after the facing process at a rolling reduction ratio appropriate for the product thickness. The rolling conditions in the first cold rolling process [Step 6] require a total reduction ratio of 70% or more to refine the crystal grains contained in the cold-rolled material after the solution heat treatment process [Step 7] described below, thereby promoting the precipitation of a second phase that is uniformly dispersed in the first phase in the aging heat treatment process [Step 9] described below. On the other hand, if the total reduction ratio is too high, it becomes difficult to increase the rolling reduction ratio in the third cold rolling process [Step 10] described below, so the total reduction ratio must be 95% or less.

[0065] (vii) Solution treatment process [Step 7] The solution treatment step (step 7) is a step of heat treating the cold-rolled material after the first cold rolling step (step 6). The conditions for the heat treatment in the solution treatment step (step 7) are that the ultimate temperature is in the range of 550°C to 750°C, and that the holding time at this ultimate temperature is in the range of 0.1 to 10 hours.

[0066] If the temperature reached in the solution treatment step [Step 7] is less than 550°C, the second phase will precipitate in the solution treatment step [Step 7] and the second phase crystals will coarsen in the aging treatment step [Step 9] described below, making it difficult to precipitate a uniform second phase. If the temperature reached in the solution treatment step [Step 7] is more than 750°C, the first phase crystals will coarsen, making it difficult to precipitate a uniform second phase in the aging treatment step [Step 9] described below.

[0067] Furthermore, if the holding time at the above-mentioned temperature in the solution treatment step [Step 7] is less than 0.1 hours, the recrystallization of the first phase will not progress sufficiently, making it difficult to obtain a uniform second phase in the aging treatment step [Step 9] described later.If the holding time at the above-mentioned temperature in the solution treatment step [Step 7] exceeds 10 hours, the crystals of the first phase will become coarse, making it difficult to precipitate a uniform second phase in the aging treatment step [Step 9] described later.

[0068] Thus, the heat treatment conditions in the solution treatment step [step 7] are such that the ultimate temperature is in the range of 550°C to 750°C and the holding time at this ultimate temperature is in the range of 0.1 to 10 hours, which allows a uniform second phase to precipitate in the aging treatment step [step 9] described later. As a result, in the third cold rolling step [step 10] described later, the second phase extending in a fibrous form along the rolling direction x can be formed with uniform phase spacing, thereby improving the tensile strength and wet etching workability of the copper alloy sheet material.

[0069] (viii) Second cold rolling process [Process 8] The second cold rolling step [Step 8] is a step in which the cold-rolled material after the solution treatment step [Step 7] is further cold-rolled. The total processing rate in the second cold rolling step [Step 8] is in the range of 20% to 80%.

[0070] Here, if the total working ratio in the second cold rolling step [Step 8] is less than 20%, the second phase is difficult to precipitate in the aging heat treatment step [Step 9] described below, making it difficult to obtain a second phase with the desired phase spacing in the third cold rolling step [Step 10] described below. Also, even if the total working ratio in the second cold rolling step [Step 8] exceeds 80%, it is difficult to obtain a second phase with the desired phase spacing. This is thought to be due to the increase in extremely fine second phase crystals, which are difficult to fiberize by rolling, in the aging heat treatment step [Step 9].

[0071] In this way, by setting the total working ratio in the second cold rolling step [step 8] to be in the range of 20% to 80%, a sufficient amount of second phase can be uniformly precipitated in the aging treatment step [step 9] described later. As a result, in the third cold rolling step [step 10] described later, the second phase extending in a fibrous form can be formed with uniform phase spacing, thereby improving the tensile strength and wet etching processability of the copper alloy sheet material.

[0072] (ix) Aging heat treatment process [Step 9] The aging heat treatment step [Step 9] is a step of heat treating the cold-rolled material after the second cold rolling step [Step 8]. In the aging heat treatment step [Step 9], heat treatment is performed at a temperature of 325°C or higher and 500°C or lower for a holding time of 0.1 hours or higher and 100.0 hours or lower. If the temperature is lower than 325°C or the holding time is shorter than 0.1 hours, the specific second phase 12 is not sufficiently generated, resulting in a decrease in tensile strength and electrical conductivity. If the temperature is higher than 500°C or the holding time is longer than 100 hours, the second phase coarsens and its proportion decreases, making it difficult to generate the specific second phase 12 extending fibrously along the rolling direction x in the first phase 11, resulting in a decrease in tensile strength and electrical conductivity.

[0073] (x) Third cold rolling process [Process 10] In the third cold rolling step [step 10], the cold-rolled material after the aging heat treatment step [step 9] is further subjected to cold rolling. Here, in the third cold rolling step [step 10], the total working ratio is adjusted to a range of 95.0% to 99.0%. By setting the total working ratio to 95.0% or more, a large number of specific second phases 12 having a long length along the rolling direction x are generated, thereby reducing the spacing of the specific second phases along the sheet thickness direction y, thereby increasing the tensile strength of the copper alloy sheet material 10. On the other hand, by setting the total working ratio in the third cold rolling step [step 10] to 99.0% or less, a decrease in electrical conductivity due to the accumulation of dislocations caused by cold rolling is less likely to occur, and a desired high electrical conductivity can be obtained.

[0074] Here, it is preferable that the rolling direction of the third cold rolling step [step 10] is substantially the same as the rolling direction of the first cold rolling step [step 6] and the second cold rolling step [step 8]. In this case, the Ag phase, which is the second phase, can be extended along the rolling direction x, which is the rolling direction of these steps.

[0075] [8] Uses of copper alloy sheets The copper alloy sheet material of the present invention is suitable for use as lead frames, connectors, terminal materials, etc. for electric and electronic equipment and vehicle-mounted parts.

[0076] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, but includes all aspects encompassed by the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention. [Example]

[0077] Next, in order to further clarify the effects of the present invention, examples of the present invention and comparative examples will be described, but the present invention is not limited to these examples of the present invention.

[0078] (Invention Examples 1 to 12 and Comparative Examples 1 to 8) A copper alloy material having the alloy composition shown in Table 1 was melted, and then cooled from the molten metal to 300°C in the atmosphere to obtain an ingot through a casting process [Step 1]. This ingot was then subjected to a homogenization heat treatment process [Step 2] in which heat treatment was performed at a holding temperature of 800°C to 1000°C for a holding time of 0.5 to 10 hours. Next, a hot rolling process [Step 3] was performed in which the ingot was rolled so that the longitudinal direction was the rolling direction, and the rolling temperature and rolling reduction ratio in the final pass were the values ​​shown in Table 2, to obtain a hot-rolled material. This was followed by a cooling process [Step 4] in which the ingot was cooled to room temperature by water cooling.

[0079] After the cooling process [Step 4], the hot-rolled material was subjected to a facing process [Step 5] to remove both the front and back surfaces and the oxide film on the surface. After that, the first cold rolling process [Step 6] was carried out, in which the material was rolled so that the longitudinal direction was the rolling direction under the total processing rate conditions shown in Table 2.

[0080] After the first cold rolling step [step 6], the rolled material was subjected to a solution treatment step [step 7] under the conditions of the temperature reached and the holding time shown in Table 2, and then a second cold rolling step [step 8] was performed in which the material was rolled so that the longitudinal direction was the rolling direction under the conditions of the total processing rate shown in Table 2.

[0081] The rolled material after the second cold rolling step [step 8] was subjected to an aging heat treatment step [step 9] under the conditions of the ultimate temperature and holding time shown in Table 2, and then a third cold rolling step [step 10] was performed in which the material was rolled so that the longitudinal direction was the rolling direction under the conditions of the total working ratio shown in Table 2. In this way, the copper alloy sheet material of the present invention was produced.

[0082] In Table 1, components other than copper (Cu) and silver (Ag), which is a second phase component, are listed as optional added components. Also, in Table 1, a horizontal line "-" is entered in the column for components that are not included in the alloy composition of the copper alloy material, indicating that the corresponding component is not included, or if it is included, it is below the detection limit.

[0083] [Various measurement and evaluation methods] The copper alloy sheets according to the above-mentioned invention examples and comparative examples were used to carry out the following characteristic evaluations. The evaluation conditions for each characteristic were as follows.

[0084] [1] Observations and measurements of specific phase 2 For each test material (copper alloy sheet material 10), a longitudinal cross section including the rolling direction x and the sheet thickness direction y was wet polished. Then, a region of 40 μm in the rolling direction × 15 μm in the sheet thickness direction was microsampled using a focused ion beam (FIB), and thin-sectioned and Ar ion milled to prepare TEM samples. The samples were observed at an accelerating voltage of 200 kV using a transmission electron microscope (TEM) (manufactured by JEOL Ltd., product name: JEM-2100Plus). A portion appearing in one field of view that had a different color tone from the Cu matrix (first phase 11) was designated as a second phase, and a portion of the second phase with a length of 1 μm or more in the rolling direction x was designated as a specific second phase 12.

[0085] The cross section including the rolling direction x and the thickness direction y was observed by a transmission electron microscope (TEM) at several randomly selected locations within the cross section in a field of view of 800 nm horizontal x 600 nm vertical. Next, for each TEM photograph, ten 5-μm-long line segments (perpendicular lines E) were drawn along the thickness direction y at intervals of 5 μm in the rolling direction x, and the total number of specific second phases 12 intersecting these line segments was counted. The sum of the lengths of the line segments drawn in the thickness direction y was then divided by the total number of specific second phases 12 intersecting each line segment plus 1 to calculate the average interphase spacing d between adjacent specific second phases 12a, 12b along the thickness direction y, which is requirement (I).

[0086] Furthermore, from these transmission electron microscope (TEM) photographs, the phase spacing d between the specific second phases 12a, 12b adjacent to each other along the thickness direction y, crossing the line segment (perpendicular line E), was measured to determine the number of phase spacings that were 10 times or more the average phase spacing. The number of phase spacings that were 10 times or more the average phase spacing that was determined was then divided by the total number of measured phase spacings d, and the result was multiplied by 100 to calculate the proportion of the number of phase spacings that were 10 times or more the average phase spacing to the total number of measured phase spacings, which is requirement (II).

[0087] [2] Analysis of crystal orientation and measurement of average aspect ratio For each of the prepared test materials (copper alloy sheet materials 10), the longitudinal section including the rolling direction x and the sheet thickness direction y was mechanically polished using waterproof abrasive paper and diamond abrasive grains, and then finish-polished using a colloidal silica solution. Then, using a scanning electron microscope (SEM), 4 μm 2 A measurement area (800 μm wide x 800 μm long) was observed, and crystal orientation analysis was performed using the EBSD method with a scan step of 0.1 μm. The crystal orientation analysis using the EBSD method was performed using OIM5.0 (product name) manufactured by TSL Solutions, Inc., and a W filament of a scanning electron microscope (manufactured by JEOL Ltd., model number: JSM-700FA) was used as the electron beam source. The scan step for the EBSD analysis was set to 0.1 μm to analyze fine crystal grains.

[0088] From the results of crystal orientation analysis of the above measured area, {011} <100> Goss direction of {011} <211> Brass orientation and {123} <634> The total area was calculated by adding up the areas of the crystal grains oriented in each of the S orientations. The total area of ​​the Goss orientation, Brass orientation, and S orientation was then divided by the above measured area to calculate the ratio of the total area of ​​the Goss orientation, Brass orientation, and S orientation to the total area of ​​all crystal grains, which is requirement (III).

[0089] In addition, the {011} <100> Goss direction of {011} <211> Brass orientation and {123} <634> For each of the crystal grains oriented in the S-orientation, the aspect ratio (a / b) was calculated, which is the ratio of the maximum length (a) of the crystal grain along the rolling direction x to the maximum length (b) of the crystal grain along the sheet thickness direction y. The total of the aspect ratios (a / b) calculated was then divided by the number of crystal grains to calculate the average aspect ratio, which is the average value of the aspect ratios of the crystal grains and is required in accordance with requirement (IV). The results of these requirements (I) to (IV) are shown in Table 1.

[0090] [3] Tensile strength measurement method The tensile strength was measured using three test pieces of No. 13B specified in JIS Z2241:2011, cut out from the test material so that the longitudinal direction was parallel to the rolling direction x. The average value of the tensile strength obtained from the three test pieces was recorded as the measured value. In this example, a tensile strength of 700 MPa or more was considered to be acceptable. The results are shown in Table 3.

[0091] [4] Electrical conductivity (EC) measurement method The electrical conductivity was calculated from the resistivity measured by the four-terminal method in a thermostatic chamber maintained at 20°C (±0.5°C). The distance between the terminals was 100 mm. In this example, a measured electrical conductivity of 70% IACS or higher was considered to be acceptable. The results are shown in Table 3.

[0092] [5] Wet etching processability measurement method Each copper alloy sheet was immersed in a ferric chloride (FeCl3) solution and wet-etched to a thickness of 10 μm along the sheet thickness direction (y). The arithmetic mean roughness (Ra) and maximum height (Ry) of the cross section perpendicular to the rolling direction (x) were measured. The arithmetic mean roughness (Ra) and maximum height (Ry) were measured using a surface roughness measuring instrument (Surfcorder SE3500) manufactured by Kosaka Laboratory Co., Ltd., in accordance with JIS-B0601 (2001). The measurement distance for the arithmetic mean roughness (Ra) and maximum height (Ry) was 4 mm, the cutoff value was 0.8 mm (in accordance with the JIS), and the scanning speed was 0.1 mm / sec. The arithmetic mean roughness (Ra) and maximum height (Ry) were measured at three different locations on the cross section, and the average of these measurements was used as the arithmetic mean roughness (Ra) and maximum height (Ry) measurements.

[0093] When the measured value of the arithmetic mean roughness (Ra) was 0.30 μm or less, the arithmetic mean roughness (Ra) of the cross section of the copper alloy sheet after wet etching was evaluated as "◎", indicating that the arithmetic mean roughness (Ra) was excellent. When the arithmetic mean roughness (Ra) was greater than 0.30 μm and less than 0.40 μm, the arithmetic mean roughness (Ra) of the cross section of the copper alloy sheet after wet etching was evaluated as "○", indicating that the arithmetic mean roughness (Ra) of the cross section of the copper alloy sheet after wet etching was at an acceptable level. On the other hand, when the arithmetic mean roughness (Ra) was greater than 0.40 μm, the arithmetic mean roughness (Ra) of the cross section of the copper alloy sheet after wet etching was evaluated as "×", indicating that the arithmetic mean roughness (Ra) was unacceptable. The results are shown in Table 3.

[0094] In addition, for the measured values ​​of the maximum height (Ry), if the maximum height (Ry) was 1.50 μm or less, the maximum height (Ry) in the cross section of the copper alloy sheet after wet etching was evaluated as "◎", indicating that it was excellent. If the maximum height (Ry) was greater than 1.50 μm and less than 1.80 μm, the maximum height (Ry) in the cross section of the copper alloy sheet after wet etching was evaluated as "○", indicating that it was at an acceptable level. On the other hand, if the maximum height (Ry) was greater than 1.80 μm, the maximum height (Ry) in the cross section of the copper alloy sheet after wet etching was evaluated as "×", indicating that it was unacceptable. The results are shown in Table 3.

[0095] Furthermore, for the evaluation results of the arithmetic mean roughness (Ra) and maximum height (Ry), if both the arithmetic mean roughness (Ra) and maximum height (Ry) were rated as "◎," the wet etching processability was deemed excellent, and the overall wet etching processability was rated as "◎." Furthermore, if one of the arithmetic mean roughness (Ra) and maximum height (Ry) was rated as "◎" and the other was rated as "〇," or if both the arithmetic mean roughness (Ra) and maximum height (Ry) were rated as "〇," the wet etching processability was deemed acceptable, and the overall wet etching processability was rated as "〇." On the other hand, if either or both of the arithmetic mean roughness (Ra) and maximum height (Ry) were rated as "×," the wet etching processability was deemed unacceptable, and the overall wet etching processability was rated as "×." The results are shown in Table 3.

[0096] [Table 1]

[0097] [Table 2]

[0098] [Table 3]

[0099] From the results of Tables 1 to 3, the copper alloy sheets 10 of Examples 1 to 12 have alloy compositions within the appropriate range of the present invention, and when viewed in a cross section including the rolling direction x and the sheet thickness direction y of the copper alloy sheet 10, the average phase spacing, which is the average value when the phase spacings d between adjacent specific second phases 12 are measured along the sheet thickness direction y, is in the range of 10 nm to 200 nm, thereby satisfying requirement (I). Furthermore, the proportion of the number of phase spacings d that are 10 times or more the average phase spacing to the total number of measured phase spacings d is 1.0% or less, thereby satisfying requirement (II). Therefore, the tensile strength is 700 MPa or more, the electrical conductivity is 70% IACS or more, and the overall evaluation of wet etching processability is evaluated as "◎" or "◯".

[0100] Therefore, the copper alloy sheet materials 10 of Examples 1 to 12 satisfied both the requirements (I) and (II), and therefore had a high tensile strength of 700 MPa or more, a high electrical conductivity of 70% IACS or more, and the overall evaluation of the wet etching processability was evaluated as "◎" or "◯", and therefore had excellent wet etching processability.

[0101] On the other hand, in the copper alloy sheets of Comparative Examples 1 to 8, at least one of the requirements (I) and (II) was outside the appropriate range of the present invention, and therefore at least one of the tensile strength, electrical conductivity, and wet etching processability did not reach an acceptable level. Among these, in Comparative Examples 1 and 2, precipitation of the specific second phase was not observed or the precipitation of the specific second phase was small, so that the average phase spacing in the obtained copper alloy sheet could not be measured, or the average phase spacing was a value exceeding 1000 nm. Therefore, in Comparative Example 2, the average phase spacing was extremely large, so the proportion of phase spacings d that were 10 times or more the average phase spacing was not calculated. [Explanation of symbols]

[0102] 10 Copper alloy plate material 11 Phase 1 12, 12a, 12b Specified Phase 2 d Phase spacing between adjacent specific second phases E perpendicular L is the total length of the second phase measured along the rolling direction x rolling direction y Thickness direction

Claims

1. The alloy has an alloy composition containing Ag in a range of 1.0 mass % to 4.0 mass % and the balance being Cu and unavoidable impurities, A copper alloy sheet material having a multi-phase structure including a first phase which is a Cu matrix phase and a second phase which is a plurality of Ag phases extending at intervals along the rolling direction, When viewed in a longitudinal section including the rolling direction and the plate thickness direction of the copper alloy plate material, Among the second phases, a second phase having a length of 1 μm or more when measured along the rolling direction is defined as a specific second phase, and when the phase spacing between adjacent specific second phases is measured along the sheet thickness direction of the copper alloy sheet, The average phase spacing, which is the average value of the phase spacings, is in the range of 10 nm to 200 nm, and the ratio of the number of phase spacings that are 10 times or more the average phase spacing to the total number of measured phase spacings is 1.0% or less, The average phase spacing is an average value of the phase spacing between adjacent specific second phases along the thickness direction, which is obtained by drawing 10 lines having a length of 5 μm along the thickness direction at intervals of 5 μm in the rolling direction on a transmission electron microscope (TEM) photograph of the longitudinal section viewed in a field of view of 800 nm horizontally × 600 nm vertically, measuring the total number of the specific second phases crossing these lines, and dividing the sum of the lengths of the lines drawn in the thickness direction by the total number of the specific second phases crossing each line, and The number of phase spacings that are 10 times or more the average phase spacing is determined by measuring the phase spacings between the specific second phases in the transmission electron microscope (TEM) photograph along which 10 line segments are drawn.

2. In a crystal orientation analysis performed by measuring the longitudinal section by an EBSD method at a scan step of 0.1 μm, the total area calculated by adding up the areas of crystal grains oriented in the {011}<100> Goss orientation, the {011}<211> Brass orientation, and the {123}<634> S orientation is 30% or less of the total area of ​​all crystal grains, and 2. The copper alloy sheet according to claim 1, wherein the crystal grains oriented in the Goss orientation, the Brass orientation, and the S orientation have an average aspect ratio, which is an average value of the aspect ratios of the crystal grains, of 5 or more and 100 or less.

3. The alloy composition further contains at least one optional additional component selected from the group consisting of 0.05 mass% or more and 1.0 mass% or less of Cr, 0.05 mass% or more and 1.0 mass% or less of Zr, 0.05 mass% or more and 1.0 mass% or less of Fe, 0.05 mass% or more and 0.5 mass% or less of Mg, and 0.05 mass% or more and 1.0 mass% or less of Zn, in a total amount of 0.05 mass% or more and 1.0 mass% or less of the copper alloy sheet material according to claim 1 or 2.

4. The copper alloy sheet material according to any one of claims 1 to 3, having a sheet thickness in the range of 0.03 mm or more and 0.20 mm or less.

5. A method for producing the copper alloy sheet material according to any one of claims 1 to 4, A copper alloy material having the alloy composition is sequentially subjected to a casting step [step 1], a homogenization heat treatment step [step 2], a hot rolling step [step 3], a water cooling step [step 4], a facing step [step 5], a first cold rolling step [step 6], a solution treatment step [step 7], a second cold rolling step [step 8], an aging heat treatment step [step 9], and a third cold rolling step [step 10]; In the casting step [Step 1], the copper alloy material is melted to prepare an ingot, In the hot rolling step [step 3], the rolling temperature in the final pass is set to 700°C or more and 800°C or less, and the rolling reduction rate in the final pass is set to 20% or more, In the first cold rolling step [step 6], the total processing rate is set to a range of 70% or more and 95% or less, In the solution treatment step [step 7], the ultimate temperature is set to a range of 550°C or more and 750°C or less, and the holding time is set to a range of 0.1 hours or more and 10 hours or less, In the second cold rolling step [step 8], the total processing rate is set to a range of 20% or more and 80% or less, In the aging heat treatment step [step 9], the ultimate temperature is set to a range of 325°C or more and 500°C or less, and the holding time is set to a range of 0.1 hours or more and 100.0 hours or less, A method for producing a copper alloy sheet material, characterized in that in the third cold rolling step [step 10], a total working ratio is set to a range of 95.0% or more and 99.0% or less.

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