Copper alloy sheet material and method for manufacturing same

Abstract

A copper alloy sheet and a method for manufacturing the same are provided. The copper alloy sheet has high tensile strength and a low temperature coefficient of resistance (TCR), thereby improving the reliability of application products such as connectors and lead frames. The copper alloy sheet has the following alloy composition: containing at least one of Ni and Co in a total of 0.50% to 5.00% by mass, Si in a range of 0.10% to 1.50% by mass, and the remainder consisting of Cu and unavoidable impurities. When the GROD value of the copper alloy sheet is determined using the EBSD method for a cross-section including the rolling direction and the thickness direction, the area ratio of grains with a measured GROD value in the range of 0° to 5° is in the range of 20% to 82%. The tensile strength is 500 MPa or more and the temperature coefficient of resistance (TCR) in the temperature range from 20°C to 150°C is 3000 ppm / °C or less. none

Description

[Technical Field]

[0001] This invention relates to a copper alloy sheet and a method for manufacturing the same, and particularly to a copper alloy sheet that can be used in application products, such as connectors and lead frames, relays, switches, etc., for electrical and electronic machinery. [Previous Technology]

[0002] Metallic materials used in applications such as connectors and lead frames, relays, and switches are required to have a low temperature coefficient of resistance (TCR) and high tensile strength, even at operating temperatures higher than room temperature. This improves reliability.

[0003] Here, the temperature coefficient of resistance (TCR) is a numerical value representing the degree of change in resistance due to temperature in parts per million (ppm) per 1°C, which can be expressed by the following formula: TCR(×10⁻⁶ / °C) = {(R-R₀) / R₀}×{1 / (T-T₀)}×10⁶. In the formula, T represents the test temperature (°C), T₀ represents the reference temperature (°C), R represents the resistance value at the test temperature T (Ω), and R₀ represents the resistance value at the reference temperature T₀ (Ω). In particular, Cu-Mn-Ni alloys and Cu-Mn-Sn alloys are widely used as alloy materials with very small TCRs.

[0004] For example, Patent Document 1 describes a Cu-Mn-Ni alloy used in wafer resistors, and describes a copper alloy in which Mn is present in a range of 21.0% by mass or more and 30.2% by mass or less, and Ni is present in a range of 8.2% by mass or more and 11.0% by mass or less, wherein the TCR value x [ppm / °C] in the temperature range from 20°C to 60°C is set in the range of -10≦x≦-2 or 2≦x≦10, and the volume resistivity ρ is set in the range of 80×10⁻⁸ [Ω・m] or more and 115×10⁻⁸ [Ω・m] or less. The copper alloy of Patent Document 1 is believed to be able to suppress the increase of Joule heating in the resistive material by controlling the magnitude of the resistance temperature coefficient (TCR).

[0005] On the other hand, as a copper alloy used in applications such as connectors and lead frames for electrical and electronic machines, a Corson Copper Alloy (Cu-Ni-Si alloy) is known.

[0006] For example, Patent Document 2 discloses a Cu-Ni-Si alloy with excellent bending workability and stress mitigation characteristics, which contains 1.0 to 4.5% by mass of Ni and 0.2 to 1.0% by mass of Si, with the remainder consisting of copper and unavoidable impurities. Furthermore, relative to the number of grains per unit area in the rolled parallel section, the proportion of grains with a grain size of 10 μm or less is 15% or more, and the proportion of grains with a grain size of 20 μm or more is 15% or more. The copper alloy of Patent Document 2 is considered to improve stress mitigation characteristics by controlling the grain size of the Cu-Ni-Si alloy. [Prior Art Documents] (Patent Documents)

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-53015. Patent Document 2: Japanese Patent Application Publication No. 2013-95977. [Summary of the Invention]

[0008] [Problem to be solved by the invention] However, although the copper alloy of Patent Document 1 has a volume resistivity ρ of 80×10⁻⁸ [Ω・m] or more and 115×10⁻⁸ [Ω・m] or less, and has a small volume resistivity when used as a chip resistor, the volume resistivity of the copper alloy is still not low enough to sufficiently suppress Joule heating. Therefore, in parts such as connectors and lead frames, relays, and switches, where high current density current flows, it is sometimes not usable unless there are very limited conditions such as low current flow and no heat dissipation effect.

[0009] Furthermore, the copper alloy in Patent Document 2 does not address the stability of the resistance as expressed by the temperature coefficient of resistance when the ambient temperature changes, nor does it reveal how to achieve a good balance between high tensile strength and low temperature coefficient of resistance, nor does it show evaluation results of such properties.

[0010] Therefore, the present invention has been made in view of the above-mentioned problems, and its object is to provide a copper alloy sheet and a method for manufacturing the same, wherein the copper alloy sheet has high tensile strength and a small temperature coefficient of resistance (TCR), thereby improving the reliability of application products such as connectors and lead frames. [Technical Means for Solving the Problem]

[0011] The inventors discovered that in a copper alloy sheet having an alloy composition, by setting the area ratio of grains with GROD values ​​ranging from 0° to 5° as measured by the EBSD method to a range of 20% to 82%, the temperature coefficient of resistance (TCR) of the copper alloy sheet decreases. This alloy composition contains at least one component of Ni and Co, totaling 0.50% to 5.00% by mass, Si, ranging from 0.10% to 1.50% by mass, and the remainder consists of Cu and unavoidable impurities. The inventors further discovered that by setting the tensile strength of such a copper alloy sheet to 500 MPa or more, a copper alloy sheet with high tensile strength and a low temperature coefficient of resistance (TCR) can be obtained, thus completing the present invention.

[0012] (1) A copper alloy sheet having the following alloy composition: containing at least one of Ni and Co in a total of 0.50% by mass and 5.00% by mass, Si in a range of 0.10% by mass and 1.50% by mass, and the remainder consisting of Cu and unavoidable impurities, wherein when the GROD value of the aforementioned copper alloy sheet is determined by the EBSD method for a cross section including the rolling direction and the thickness direction, the area ratio of the grains in the range of 0° and 5° is 20% or more and 82% or less, the tensile strength is 500 MPa or more, and the temperature coefficient of resistance (TCR) in the temperature range from 20° to 150° is 3000 ppm / °C or less.

[0013] (2) The copper alloy sheet as described in (1) above, wherein the aforementioned alloy composition further contains at least one component selected from the group consisting of Mg, Sn, Zn, P, Cr and Zr in a total range of 0.10% by mass or more and 1.00% by mass or less.

[0014] (3) A method for manufacturing a copper alloy sheet, which is the method for manufacturing a copper alloy sheet as described in (1) or (2) above, wherein the manufacturing method, for a copper alloy material having the same alloy composition as described above, sequentially performs the following steps: melting and casting step [step 1], homogenization step [step 2], hot rolling step [step 3], planar cutting step [step 4], first cold rolling step [step 5], first heat treatment step [step 6], second heat treatment step [step 8] and finishing step [step 9]; in the aforementioned first heat treatment step [step 6], the heating temperature is in the range of 750°C or higher and 1000°C or lower; In the second heat treatment step [step 8], the heating temperature is in the range of 450°C or higher and 550°C or lower; the aforementioned finishing step [step 9] consists of finishing cold rolling with two or more passes [step 9-1] and finishing heat treatment [step 9-2] performed after each pass of the aforementioned finishing cold rolling [step 9-1]. In the aforementioned finishing cold rolling [step 9-1], the maximum partial processing rate of each pass is in the range of 4% or higher and 10% or lower, and the total processing rate is in the range of 10% or higher and 40% or lower. In the aforementioned finishing heat treatment [step 9-2], the heating temperature is in the range of 300°C or higher and 400°C or lower.

[0015] (4) The method for manufacturing copper alloy sheet as described in (3) above, wherein a second cold rolling step [step 7] is further performed between the aforementioned first heat treatment step [step 6] and the aforementioned second heat treatment step [step 8], wherein the total processing rate in the aforementioned second cold rolling step [step 7] is set in the range of 5% or more and 70% or less. [Effects of the Invention]

[0016] According to the present invention, a copper alloy sheet and a method for manufacturing the same can be provided. The copper alloy sheet has high tensile strength and a small temperature coefficient of resistance (TCR), thereby improving the reliability of application products such as connectors and lead frames.

Implementation Method

[0018] Next, embodiments of the present invention will be described. The following description is an example illustrating embodiments of the present invention and is not intended to limit the scope of the invention claims.

[0019] The copper alloy sheet according to the present invention is a copper alloy sheet having the following alloy composition, wherein the alloy composition contains at least one component of Ni and Co in a total of 0.50% by mass and 5.00% by mass, Si in a range of 0.10% by mass and 1.50% by mass, and the remainder is composed of Cu and unavoidable impurities. When the GROD value is determined by the EBSD method for a cross section including the rolling direction and the thickness direction of the aforementioned copper alloy sheet, the area ratio of the grains with the aforementioned GROD value in the range of 0° and 5° is in the range of 20% to 82%, the tensile strength is 500 MPa or more, and the temperature coefficient of resistance (TCR) in the temperature range from 20° to 150° is 3000 ppm / °C or less.

[0020] Preferably, the copper alloy sheet of the present invention contains at least one of Ni and Co and a Si component in appropriate amounts, and when measuring the GROD value using the EBSD method for a cross-section including the rolling direction and the thickness direction, the area ratio of grains with measured GROD values ​​in the range of 0° to 5° is set to be 20% to 82% or more. In particular, by setting the area ratio of grains with GROD values ​​in the range of 0° to 5° to be 20% or more, the temperature coefficient of resistance (TCR) in the temperature range from 20°C to 150°C can be reduced. Furthermore, by setting the area ratio of grains with GROD values ​​in the range of 0° to 5° to be 82% or less, the tensile strength of the copper alloy sheet can be improved, particularly the tensile strength. In particular, when the tensile strength of the copper alloy sheet is made to be 500 MPa or more, the present invention can obtain a copper alloy sheet with high tensile strength and low temperature coefficient of resistance (TCR). Therefore, the copper alloy sheet of the present invention provides a copper alloy sheet and a method for manufacturing the same, which has high tensile strength and a low temperature coefficient of resistance (TCR). As a result, the reliability of application products such as connectors and lead frames can be improved.

[0021] [1] Alloy composition of copper alloy sheet The alloy composition of the copper alloy sheet of the present invention, as an essential component, contains: at least one of Ni and Co in a total of 0.50% by mass or more and 5.00% by mass or less, and Si in a range of 0.10% by mass or more and 1.50% by mass or less. Hereinafter, the reasons for limiting the alloy composition of the copper alloy sheet will be explained.

[0022] (Ni and Co: at least one component totaling 0.50% by mass or more and 5.00% by mass or less) Ni (nickel) and Co (cobalt) are both important components that improve the tensile strength of copper alloy sheets. Here, if the total content of Ni and Co is less than 0.50% by mass, the tensile strength of the copper alloy sheet will decrease and the temperature coefficient of resistance (TCR) will increase. Furthermore, if the total content of Ni and Co exceeds 5.00% by mass, coarse precipitates will easily form in the ingot. As a result, after the first heat treatment step [step 6] described later, the precipitates will remain in an undissolved state, and therefore, they will easily become the starting point for cracks when the copper alloy sheet is subjected to machining such as bending. Furthermore, if the total content of Ni and Co exceeds 5.00% by mass, the material cost of the copper alloy sheet will also easily increase. Therefore, it is necessary to add one or both of Ni and Co, and these components must be present in a total content of 0.50% by mass or more and 5.00% by mass or less. In particular, the combined content of Ni and Co is preferably set in the range of 1.50% by mass or more and 5.00% by mass or less, and more preferably in the range of 2.50% by mass or more and 5.00% by mass or less.

[0023] (Si: 0.10% by mass or more and 1.50% by mass or less) Si (silicon) is an important component that enhances the tensile strength of copper alloy sheets. From the viewpoint of enabling this function, the Si content needs to be set to 0.10% by mass or more. On the other hand, if the Si content exceeds 1.50% by mass, it becomes easy to generate coarse precipitates in the ingot. As a result, after the first heat treatment step [step 6] described later, the precipitates will still remain in an undissolved state. Therefore, when performing machining such as bending on the copper alloy sheet, it is easy to become the starting point of cracks. Therefore, it is necessary to contain Si in the range of 0.10% by mass or more and 1.50% by mass or less. In particular, it is preferable to set the Si content in the range of 0.20% by mass or more and 1.40% by mass or less, and more preferably in the range of 0.30% by mass or more and 1.30% by mass or less.

[0024] <Optional Additives> Furthermore, the copper alloy sheet of the present invention may contain at least one component selected from the group consisting of Mg, Sn, Zn, P, Cr and Zr as optional additives in a total range of 0.10% by mass or more and 1.00% by mass or less.

[0025] (Mg: 0.10% by mass or more and 0.30% by mass or less) Mg (magnesium) is a component that enhances stress-relieving properties. To achieve this effect, it is preferable to set the Mg content to 0.10% by mass or more. On the other hand, if the Mg content exceeds 0.30% by mass, the electrical conductivity tends to decrease. Therefore, the Mg content is preferably in the range of 0.10% by mass or more and 0.30% by mass or less.

[0026] (Sn: 0.10% by mass or more and 0.30% by mass or less) Sn (tin) is a component that enhances stress-relieving properties. To achieve this effect, it is preferable to set the Sn content to 0.10% by mass or more. On the other hand, if the Sn content exceeds 0.30% by mass, the conductivity tends to decrease. Therefore, the Sn content is preferably in the range of 0.10% by mass or more and 0.30% by mass or less.

[0027] (Zn: 0.10% by mass or more and 0.50% by mass or less) Zn (zinc) is a component that improves the adhesion and migration properties of Sn plating. To achieve this effect, it is preferable to set the Zn content to 0.10% by mass or more. On the other hand, if the Zn content exceeds 0.50% by mass, the conductivity tends to decrease. Therefore, the Zn content is preferably in the range of 0.10% by mass or more and 0.50% by mass or less.

[0028] (P: 0.10% by mass or more and 0.30% by mass or less) Phosphorus (P) is a component that can suppress the precipitation of Si compounds at grain boundaries and improve the tensile strength of copper alloy sheets. For this effect to be effective, the P content is preferably 0.10% by mass or more. On the other hand, if the P content exceeds 0.30% by mass, the conductivity tends to decrease. Therefore, the P content is preferably in the range of 0.10% by mass or more and 0.30% by mass or less.

[0029] (Cr: 0.10% by mass or more and 0.30% by mass or less) Cr (chromium) is a component that inhibits grain roughening during molten heat treatment. For this effect to be effective, the Cr content is preferably 0.10% by mass or more. On the other hand, if the Cr content exceeds 0.30% by mass, coarse Cr-containing precipitates become more likely to form during casting, thus increasing the likelihood of crack initiation. Therefore, the Cr content is preferably in the range of 0.10% by mass or more and 0.30% by mass or less.

[0030] (Zr: 0.10% by mass or more and 0.20% by mass or less) Zr (zirconium) is a component that helps to suppress grain roughening during molten heat treatment. To achieve this effect, it is preferable to set the Zr content to 0.10% by mass or more. On the other hand, if the Zr content exceeds 0.20% by mass, coarse Zr-containing precipitates will easily form during casting, which will make it easier to form the initiation point of cracks. Therefore, the Zr content is preferably in the range of 0.10% by mass or more and 0.20% by mass or less.

[0031] (Total content of any added ingredients: 0.10% by mass or more and 1.00% by mass or less) These added ingredients can achieve the effects produced by the above-mentioned added ingredients, so it is preferable that they contain a total of 0.10% by mass or more. On the other hand, if these added ingredients are contained in large quantities, they will easily form compounds with the required ingredients, so it is preferable that they contain a total of 1.00% by mass or less.

[0032] (Remaining portion: Cu and unavoidable impurities) The copper alloy constituting the copper alloy sheet, in addition to the above-mentioned components, has an alloy composition consisting of Cu (copper) and unavoidable impurities as the remaining portion. Furthermore, the "unavoidable impurities" referred to here are permissible impurities, which are components present in the raw materials in most metal products, or components that are unavoidably mixed in during the manufacturing process and are originally unwanted, but are present in trace amounts and do not affect the properties of the metal product, and are therefore permissible. Examples of unavoidable impurities include, for example, non-metallic elements such as S (sulfur), C (carbon), and O (oxygen), and metallic elements such as Sb (antimony). Furthermore, the upper limit of the content of these components, for example, can be set to 0.05% by mass for each of the above components, and 0.20% by mass for the total amount of the above components.

[0033] [2] The GROD value and its area ratio GROD (Grain Reference Orientation Deviation) value of the copper alloy sheet are values ​​obtained based on the crystal orientation analysis data of the EBSD method, and show the value of misorientation within the same grain relative to a reference point. Here, the reference point is the measurement point where the KAM value is the smallest within the grain. In addition, the KAM (Kernel Average Misorientation) value is the average value of the crystallographic misorientation between the measurement point and all measurement points adjacent to that measurement point.

[0034] In the copper alloy sheet of the present invention, when the GROD value is measured using the EBSD method for a cross-section including the rolling direction and the thickness direction, the area ratio of grains with a measured GROD value in the range of 0° to 5° is in the range of 20% to 82%. This allows for sufficient stabilization of dislocations in the copper alloy sheet, thereby reducing the temperature coefficient of resistance (TCR). Here, if this area ratio is less than 20%, the temperature coefficient of resistance (TCR) will increase. Furthermore, if this area ratio is greater than 82%, the tensile strength of the copper alloy sheet will decrease. Therefore, the area ratio of grains with a GROD value in the range of 0° to 5° needs to be set in the range of 20% to 82%. In particular, the area ratio of grains with a GROD value in the range of 0° to 5° is preferably set in the range of 30% to 70%, and more preferably in the range of 40% to 60%.

[0035] The GROD value can be obtained from crystal orientation analysis data. This data is obtained by continuously measuring crystal orientation data using an EBSD detector attached to a high-resolution scanning analytical electron microscope (manufactured by JEOL Ltd., JSM-7001FA), and then calculating it using analysis software (manufactured by TSL Ltd., OIM Analysis). Here, "EBSD" is an abbreviation for Electron BackScatter Diffraction, a crystal orientation analysis technique that utilizes reflected electron Kikuchi line diffraction, which is generated when electron beams are irradiated onto the sample within a scanning electron microscope (SEM). "OIM Analysis" is the software used to analyze the data measured by EBSD. The measurements are performed in a field of view of approximately 400 μm × 800 μm, with a distance between measurement points (hereinafter also referred to as step size) of 0.5 μm. The measurement area can be performed on a cross-section along the rolling direction, which is formed by embedding a copper alloy sheet in resin and then finishing it with mechanical grinding and polishing (silicone). Here, when the sheet thickness is less than 800 μm, the measurement range along the rolling direction can be increased to create a measurement surface with the same dimensions as 400 μm × 800 μm. Here, measurement points with a reliability index (CI) value of 0.1 or higher are selected as the analysis targets.

[0036] Furthermore, a boundary with a misalignment of 15° or more is defined as a grain boundary. When the grain outline is drawn based on this grain boundary, the measurement point with the smallest KAM value in the same grain is used as the reference point. For all measurement points set as the analysis object, the misalignment relative to the reference point in each grain is calculated, thereby allowing the GROD value of the measurement points set as the analysis object to be calculated separately. At this time, the area ratio of grains with GROD values ​​in the range of 0° to 5° can be calculated from the ratio of the number of measurement points with GROD values ​​in the range of 0° to 5° to the total number of measurement points with calculated GROD values.

[0037] [3] Tensile strength of copper alloy sheet The copper alloy sheet of the present invention must have a tensile strength of 500 MPa or more when stretched in a direction parallel to the rolling direction. In this way, even when the copper alloy sheet is used in applications such as connectors and lead frames, relays, switches, etc., the desired tensile strength can still be obtained, thereby improving the reliability of the copper alloy sheet in such applications.

[0038] Here, the tensile strength is measured on two test pieces, and the average value of the tensile strength obtained from the two test pieces when stretched in the length direction is set as the measured value of the tensile strength. The test pieces are cut in a direction parallel to the rolling direction as the length direction, and are of No. 13B as specified in Japanese Industrial Standard JIS Z2241:2011.

[0039] [4] Temperature Coefficient of Resistance (TCR) of Copper Alloy Sheet The copper alloy sheet of the present invention must have a temperature coefficient of resistance (TCR) of less than 3000 ppm / ℃ over a temperature range from 20℃ to 150℃. This allows for a narrowing of the temperature coefficient of resistance over a wider temperature range from room temperature (e.g., 20℃) to high temperature (e.g., 150℃), thereby ensuring that the copper alloy sheet has the same resistance at both room temperature and operating temperature, thus improving the reliability of using the copper alloy sheet in applications such as connectors and lead frames, relays, and switches.

[0040] Here, the temperature coefficient of resistance (TCR) is expressed as the magnitude of the change in resistance due to temperature in parts per million per 1°C. The temperature coefficient of resistance (TCR) can be measured by the following method: using the four-terminal method specified in Japanese Industrial Standard JIS C2526, the resistance value R150°C [mΩ] at 150°C and the resistance value R20°C [mΩ] at 20°C are obtained. Then, using these values ​​of R150°C and R20°C, the temperature coefficient of resistance (ppm / °C) is calculated using the formula TCR = {(R150°C [mΩ] - R20°C [mΩ]) / R20°C [mΩ]} × {1 / (150°C - 20°C])} × 10⁶. Here, R150 ℃ and R20 ℃ can be determined by cutting a copper alloy plate into test materials with a width of 10 mm and a length of 300 mm, setting the distance between voltage terminals to 200 mm and the measuring current to 100 mA, and using the four-terminal method specified in Japanese Industrial Standard JIS C2526, measuring the voltage when the temperature of the test material is set to 20℃ and 150℃ respectively.

[0041] [5] An example of a method for manufacturing copper alloy sheet The copper alloy sheet described above can be achieved by combining and controlling the alloy composition and manufacturing process, and the manufacturing process is not particularly limited. Among these, the following method can be cited as an example of a manufacturing process that can obtain such a copper alloy sheet having high tensile strength and a small temperature coefficient of resistance (TCR).

[0042] One example of the method for manufacturing the copper alloy sheet of the present invention involves performing at least the following steps sequentially on a copper alloy material having an alloy composition having the same degree of alloy composition as the copper alloy sheet described above: a melting and casting step [Step 1], a homogenization step [Step 2], a hot rolling step [Step 3], a planar cutting step [Step 4], a first cold rolling step [Step 5], a first heat treatment step [Step 6], a second heat treatment step [Step 8], and a finishing step [Step 9]. In the first heat treatment step [Step 6], the heating temperature is set to a range of 750°C or higher and 1000°C or lower. Furthermore, in the second heat treatment step [Step 8], the heating temperature is set to a range of 450°C or higher and 550°C or lower. Furthermore, the finishing step [Step 9] consists of two or more passes of finishing cold rolling [Step 9-1] and finishing heat treatment [Step 9-2] performed after each pass of finishing cold rolling [Step 9-1]. In the finishing cold rolling [step 9-1], the maximum partial processing rate for each pass is set between 4% and 10%, and the total processing rate is set between 10% and 40%. Furthermore, in the finishing heat treatment [step 9-2], the heating temperature is set between 300°C and 400°C.

[0043] (i) Melting and Casting Step [Step 1] The melting and casting step [Step 1] is the following step: melting a copper alloy material having an alloy composition with the same degree as the above-mentioned alloy composition, and then casting it to produce an ingot of a specific shape (e.g., 30 mm thick, 100 mm wide, and 150 mm long). The melting and casting step [Step 1] is preferably performed by melting and casting the copper alloy material in an atmosphere, an inert gas atmosphere, or a vacuum, for example, using a high-frequency melting furnace. Furthermore, the alloy composition of the copper alloy material may not be completely consistent with the alloy composition of the manufactured copper alloy sheet due to the adhesion or volatilization of added components in the melting furnace during the various manufacturing steps, but it still has an alloy composition substantially the same as the alloy composition of the copper alloy sheet.

[0044] (ii) Homogenization Step [Step 2] The homogenization step [Step 2] is a heat treatment step performed on the ingot after the melting and casting step [Step 1]. The conditions for the heat treatment in the homogenization step [Step 2] are not particularly limited, as long as they are the normally performed conditions. As an example of the heat treatment conditions here, it is a heating temperature in the range of 850°C or higher and 1000°C or lower, and a heating time in the range of 1 hour or higher and 6 hours or lower.

[0045] (iii) Hot rolling step [Step 3] The hot rolling step [Step 3] is a step of producing hot-rolled material by hot rolling the ingot that has undergone the homogenization step [Step 2] until it reaches a specified thickness. In the hot rolling step [Step 3], for example, it is preferable to set the rolling temperature to 700°C or higher and the total reduction rate (total shrinkage rate) to 50% or higher.

[0046] Here, the [processing rate] (rolling reduction rate) is a percentage value calculated by subtracting the cross-sectional area after rolling from the cross-sectional area before rolling, dividing by the cross-sectional area before rolling, multiplying by 100, and then expressing it as a percentage. It can be expressed by the following formula: [Processing Rate] = {([Cross-sectional area before rolling] - [Cross-sectional area after rolling]) / [Cross-sectional area before rolling] × 100 (%)}

[0047] The hot-rolled material after the hot rolling step [step 3] is preferably cooled. Here, there is no particular limitation on the means of cooling the hot-rolled material, but from the viewpoint that it is less likely to cause grain roughening, it is preferable to increase the cooling rate as much as possible, for example, by means of water cooling, to set the cooling temperature to 10°C / second or more.

[0048] (iv) Planar cutting step [Step 4] The plane cutting step [Step 4] is a step for removing the surface of the hot-rolled material. By performing the plane cutting step [Step 4], the oxide film and defects generated on the surface in the hot rolling step [Step 3] can be removed. The plane cutting conditions for the plane cutting step [Step 4] are not particularly limited, as long as they are the conditions normally performed. The amount removed from the surface of the hot-rolled material by plane cutting can be appropriately adjusted based on the conditions of the hot rolling step [Step 3] and the oxidation state of the surface of the hot-rolled material. For example, it can be set to about 0.5 mm to 5 mm from both sides of the hot-rolled material.

[0049] (v) First Cold Rolling Step [Step 5] The first cold rolling step [Step 5] is a step of cold rolling the hot-rolled material after the planar cutting step [Step 4]. The rolling in the first cold rolling step [Step 5] can be carried out with any shrinkage rate according to the thickness of the product plate, for example, the total processing rate can be set in the range of 50% or more and 99.9% or less.

[0050] (vi) First heat treatment step [step 6] The first heat treatment step [step 6] is a step of performing heat treatment on the cold-rolled material after the first cold rolling step [step 5] according to the alloy composition.

[0051] In the heat treatment of the first heat treatment step [step 6], by setting the heating temperature to a range of 750°C or higher and 1000°C or lower, the added element components can be dissolved, thereby increasing the precipitation hardening amount in the second heat treatment step [step 8] described later, and as a result, the tensile strength of the obtained copper alloy sheet can be improved. In particular, in the heat treatment of the first heat treatment step [step 6], by setting the heating time at the above-mentioned heating temperature to a range of 1 second or higher and 60 seconds or lower, more added element components can be dissolved, and the precipitation hardening amount in the second heat treatment step [step 8] can be further improved. On the other hand, when the heating temperature of the heat treatment of the first heat treatment step [step 6] is lower than 750°C, the Ni and Si components cannot be sufficiently dissolved, so the precipitation amount in the second heat treatment step [step 8] will be insufficient, and thus the precipitation hardening amount in the second heat treatment step [step 8] will be less, and the tensile strength of the obtained copper alloy sheet will become less than 500 MPa. Furthermore, when the heating temperature of the heat treatment in the first heat treatment step [step 6] is higher than 1000°C, the tensile strength of the obtained copper alloy plate will become less than 500 MPa due to the roughening of the grain size, etc.

[0052] (vii) Second Cold Rolling Step [Step 7] The second cold rolling step [Step 7] is a step of further cold rolling the cold-rolled material after the first heat treatment step [Step 6], and is an arbitrary step. That is, in the method for manufacturing copper alloy sheet of the present invention, it is preferable to further perform the second cold rolling step [Step 7] between the first heat treatment step [Step 6] and the second heat treatment step [Step 8]. This can further increase the precipitation hardening amount in the second heat treatment step [Step 8]. On the other hand, in the method for manufacturing copper alloy sheet of the present invention, the second heat treatment step [Step 8] can also be performed without performing the second cold rolling step [Step 7] after performing the first heat treatment step [Step 6].

[0053] Here, the rolling in the second cold rolling step [step 7] can be carried out at any processing rate (rolling rate) to match the desired product thickness, for example, the total processing rate can be set in the range of 5% or more and 70% or less.

[0054] (viii) Second heat treatment step [step 8] The second heat treatment step [step 8] is a heat treatment step that performs heat treatment on the cold-rolled material after the second cold rolling step [step 7] to make it age harden.

[0055] Here, the heating temperature in the second heat treatment step [step 8] is set to a range of 450°C or higher and 550°C or lower. When the heating temperature is below 450°C, insufficient precipitation will result in less precipitation hardening, and the tensile strength of the obtained copper alloy sheet will be less than 500 MPa. Furthermore, when the heating temperature is above 550°C, roughening of the precipitates will reduce the precipitation hardening energy, and the tensile strength of the obtained copper alloy sheet will also be less than 500 MPa. Therefore, the heat treatment temperature in the second heat treatment step [step 8] needs to be set to a range of 450°C or higher and 550°C or lower. In particular, from the viewpoint of obtaining higher tensile strength, the heat treatment temperature in the second heat treatment step [step 8] is preferably set to 470°C or higher and 530°C or lower.

[0056] Furthermore, the heating time in the second heat treatment step [step 8] is preferably a holding time of 1 hour or more and 7 hours or less. In this case, if the heating time is less than 1 hour or more than 7 hours, the amount of precipitation hardening will decrease due to the roughening of the precipitates, resulting in a decrease in the tensile strength of the obtained copper alloy sheet. Therefore, the heating time in the second heat treatment step [step 8] is preferably a holding time of 1 hour or more and 7 hours or less.

[0057] The cold-rolled material after the second heat treatment step [step 8] is preferably cooled immediately. Here, there are no particular limitations on the means of cooling the hot-rolled material; water cooling, air cooling, natural cooling, etc., can be used. For example, when cooling by water cooling, the cooling rate can be set to 50°C / second or more. Furthermore, when cooling by natural cooling, the cooling rate can be set in the range of 50°C / hour or more and 100°C / hour or less.

[0058] (ix) Finishing Step [Step 9] The finishing step [Step 9] is a finishing step that adjusts the tensile strength and temperature coefficient of resistance (TCR) of the sheet material by performing two or more sets of cold rolling and heat treatment as a single process on the cooled cold-rolled material. More specifically, the finishing step [Step 9] consists of two or more passes of finishing cold rolling [Step 9-1] and finishing heat treatment [Step 9-2] performed after each pass of finishing cold rolling [Step 9-1]. By performing two or more sets of such finishing cold rolling [Step 9-1] and finishing heat treatment [Step 9-2], the dislocations introduced by cold rolling can be stabilized by the finishing heat treatment, thereby enabling the dislocations to be dispersed at a high density. By dispersing the misalignments at a high density in this way, the area ratio of grains with GROD values ​​between 0° and 5° can be controlled to be between 20% and 82%, thereby increasing the tensile strength of the obtained copper alloy sheet and reducing the temperature coefficient of resistance (TCR). On the other hand, when only one set of finishing cold rolling [step 9-1] and finishing heat treatment [step 9-2] is performed, the misalignments cannot be dispersed at a high density, and therefore the tensile strength of the obtained copper alloy sheet becomes less than 500 MPa.

[0059] In the finishing cold rolling [step 9-1], the maximum value of the partial processing rate of each pass is in the range of 4% to 10%, and the total processing rate is in the range of 10% to 40%. Here, the "partial processing rate of each pass" is a value obtained by subtracting the cross-sectional area of ​​the sheet material after the rolling pass before the finishing cold rolling [step 9-1] from the cross-sectional area of ​​the sheet material after the rolling pass, dividing the obtained value by the cross-sectional area of ​​the sheet material before the rolling pass, and then multiplying by 100. In addition, the "total processing rate" is a value obtained by subtracting the cross-sectional area of ​​the cold-rolled material after the final finishing cold rolling [step 9-1] from the cross-sectional area of ​​the cold-rolled material before the initial finishing cold rolling [step 9-1], dividing the obtained value by the cross-sectional area of ​​the cold-rolled material before the initial finishing cold rolling [step 9-1], and then multiplying by 100. In this process, partial processing can be performed in at least one of two or more passes with a partial processing rate of 4% to 10%, while other passes can have a processing rate of less than 4%. However, if the maximum partial processing rate in each pass is less than 4%, even repeated heat treatment will reduce the effect on improving tensile strength, resulting in a copper alloy sheet with a tensile strength of less than 500 MPa. On the other hand, in the finishing cold rolling [step 9-1], rolling with a partial processing rate exceeding 10% in each pass is not performed. If a partial processing rate exceeding 10% in each pass is performed, the misalignment will increase, making sufficient stabilization impossible. Consequently, the area ratio of grains with a GROD value between 0° and 5° will be less than 20%, and the temperature coefficient of resistance (TCR) will be greater than 3000 ppm / °C. In particular, from the viewpoint of improving tensile strength by reducing the number of finishing heat treatments [step 9-2], finishing cold rolling [step 9-1] is preferably carried out in 5 passes or less, and more preferably in 2 passes.

[0060] Furthermore, when the total processing rate in finishing cold rolling [step 9-1] is less than 10%, the work hardening amount decreases, thus failing to sufficiently improve the tensile strength of the copper alloy sheet, resulting in a tensile strength of less than 500 MPa. On the other hand, when the total processing rate in finishing cold rolling [step 9-1] exceeds 40%, the area ratio of grains with GROD values ​​between 0° and 5° is less than 20%, causing the temperature coefficient of resistance (TCR) to exceed 3000 ppm / °C. Therefore, the total processing rate in finishing cold rolling [step 9-1] needs to be set within the range of 10% to 40%. In particular, from the viewpoint of balancing tensile strength and temperature coefficient of resistance, the total processing rate in finishing cold rolling [step 9-1] is preferably set within the range of 10% to 30%, and more preferably within the range of 17% to 30%.

[0061] The finishing heat treatment [step 9-2] involves heating temperatures ranging from 300°C to 400°C. Specifically, from the viewpoint of obtaining higher tensile strength, the heating temperature in the finishing heat treatment [step 9-2] is preferably in the range of 300°C to 380°C. At this temperature, when the heating temperature is below 300°C, the area ratio of grains with a GROD value between 0° and 5° will be less than 20%, and thus the temperature coefficient of resistance (TCR) will become greater than 3000 ppm / °C. On the other hand, if the heating temperature is above 400°C, the tensile strength of the obtained copper alloy sheet will become less than 500 MPa due to the slow recovery of dislocations and roughening of precipitates. Furthermore, if the heating temperature in the first heat treatment step [step 6] is above 1000°C and the heating temperature in the finishing heat treatment [step 9-2] is above 400°C, the area ratio of grains with a GROD value between 0° and 5° will become greater than 82%. Furthermore, there is no particular limitation on the heating time in the finishing heat treatment [step 9-2], for example, it can be set to a range of more than 10 seconds and less than 60 seconds.

[0062] [6] Applications of Copper Alloy Sheets The copper alloy sheets of the present invention are applicable to electrical and electronic parts, etc. More specifically, they are suitable for use in applications where high current density currents flow through them, such as connectors, lead frames, relays, switches, etc., for electrical and electronic equipment.

[0063] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, but also includes all embodiments contained in the concept and scope of the present invention, and various changes can be made within the scope of the present invention. [Example]

[0064] Next, in order to further clarify the effects of the present invention, examples and comparative examples of the present invention will be described, but the present invention is not limited to these examples.

[0065] (Examples 1-17 of the present invention and Comparative Examples 1-13) Various copper alloy materials having the alloy composition shown in Table 1 were melted in a high-frequency melting furnace, and then cooled in the atmosphere and cast [Step 1] to obtain an ingot. This ingot was then subjected to a homogenization heat treatment at a heating temperature of 850°C or higher and 1000°C or lower for a heating time of 1 hour [Step 2], followed immediately by hot rolling treatment with the length direction of the ingot aligned with the rolling direction at a total processing rate of 50% or higher [Step 3], to obtain a hot-rolled material. Afterwards, it was cooled to room temperature by water cooling.

[0066] After the cooled hot-rolled material is subjected to a planar cutting step [step 4] to remove the oxide film on the surface by cutting off about 0.5 mm to 5 mm from both sides by planar cutting, a first cold rolling step [step 5] is performed with the length direction of the hot-rolled material becoming the rolling direction under the condition that the total processing rate is 90%.

[0067] For the rolled material after the first cold rolling step [step 5], a first heat treatment step [step 6] is performed with heat treatment under the conditions recorded in Table 2, and then a second cold rolling step [step 7] is performed with the length direction of the rolled material becoming the rolling direction under the conditions of the total processing rate [%] recorded in Table 2.

[0068] For the rolled material after the second cold rolling step [step 7], a second heat treatment step [step 8] is performed under the conditions of heating temperature and heating time as recorded in Table 2, and then immediately cooled to room temperature by water cooling.

[0069] For the cooled rolled material, finishing cold rolling [step 9-1] and finishing heat treatment [step 9-2] are performed as finishing steps [step 9]. The finishing cold rolling [step 9-1] is performed with the number of passes and the partial processing rate of each pass as recorded in Table 2. The finishing heat treatment [step 9-2] is performed after each pass of finishing cold rolling [step 9-1] with the heating temperature and heating time recorded in Table 2. At this time, the total processing rate in finishing cold rolling [step 9-1] is as recorded in Table 2.

[0070] Furthermore, in Table 1, components other than copper (Cu), nickel (Ni), cobalt (Co), and silicon (Silicon) are listed as optional additives. In addition, in Table 1, the columns for components not included in the alloy composition of copper alloy materials are marked with a horizontal line "-", which clearly indicates that the component is not present or that even if the component is present, it is below the detection limit value.

[0071] [Various Measurement and Evaluation Methods] Using the copper alloy plates from the above-described examples and comparative examples of the present invention, the following characteristic evaluations were performed. The evaluation conditions for each characteristic are as follows.

[0072] [1] GROD value and area ratio of copper alloy sheet The GROD value of copper alloy sheet was obtained from crystal orientation analysis data. The crystal orientation analysis data was obtained from the copper alloy sheet obtained by the present invention and the comparative example. The measurements were continuously performed using an EBSD detector attached to a high-resolution scanning analytical electron microscope (manufactured by Nippon Electronics Co., Ltd., JSM-7001FA). The measured crystal orientation data was then calculated using analysis software (manufactured by TSL Corporation, OIM Analysis). The measurements were performed in a field of view of approximately 400 μm × 800 μm with a distance between measurement points (hereinafter also referred to as step size) of 0.5 μm. The measurement area was a cross section including the rolling direction and the thickness direction. The cross section including the rolling direction and the thickness direction was finished by mechanical grinding and polishing (silicone) of the copper alloy sheet embedded in resin. Here, even when the plate thickness is less than 800 μm, the measurement range can be increased along the rolling direction by making the measurement surface the same size as 400 μm × 800 μm. The analysis based on the analysis software sets measurement points with a reliability index (CI) value of 0.1 or higher as the analysis object. Furthermore, boundaries with a misalignment of 15° or more are defined as grain boundaries. When the grain outline is drawn based on these grain boundaries, the measurement point with the smallest KAM value in the grain is considered the reference point for each grain. Then, for all measurement points set as the analysis object, the misalignment relative to these reference points is calculated, thereby calculating the GROD value for each measurement point set as the analysis object. The area ratio of grains with GROD values ​​in the range of 0° to 5° is calculated from the proportion of measurement points with GROD values ​​in the range of 0° to 5° relative to the total number of measurement points obtained in this operation. Furthermore, in this embodiment, grains with a GROD value between 0° and 5° and an area ratio between 20% and 82% are classified as qualified. The results are shown in Table 3.

[0073] [2] Determination of the tensile strength of copper alloy sheet The tensile strength was determined using two test pieces of No. 13B as specified in Japanese Industrial Standard JIS Z2241. The average tensile strength obtained from the two test pieces was then taken as the measured value. The test pieces were sample materials cut in a direction parallel to the rolling direction as the length direction. Here, the test pieces were made of sheet material with a thickness of 0.3 mm. Furthermore, in this embodiment, a tensile strength of 500 MPa or above for the copper alloy sheet was set as the qualified grade. The results are shown in Table 3.

[0074] [3] Measurement of temperature coefficient of resistance (TCR) For Examples 1 to 17 of the present invention and Comparative Examples 1 to 13, the obtained copper alloy plate with a thickness of 0.3 mm was cut into a width of 10 mm and a length of 300 mm to prepare sample materials.

[0075] The temperature coefficient of resistance (TCR) is determined by setting the distance between the voltage terminals to 200 mm and the measurement current to 100 mA, using a four-terminal method as specified in Japanese Industrial Standard JIS C2526. The voltage is measured when the sample material is heated to 150°C, and the resistance value R150 [mΩ] at 150°C is calculated from the obtained value. Then, the voltage is measured when the sample material is cooled to 200°C, and the resistance value R20 [mΩ] at 20°C is calculated from the obtained value. Then, using the obtained resistance values, namely R150℃ and R20℃, the temperature coefficient of resistance (ppm / ℃) for the temperature range from 20℃ to 150℃ is calculated based on the formula TCR = {(R150℃[mΩ]-R20℃[mΩ]) / R20℃[mΩ]}×{1 / (150[℃]-20[℃])}×10 6. Furthermore, in this embodiment, a temperature coefficient of resistance (TCR) of 3000ppm / ℃ or lower is considered acceptable. The results are shown in Table 3.

[0076] [Table 1]

[0077] [Table 2]

[0078] [Table 3]

[0079] Based on the results in Tables 1 to 3, the copper alloy plates of Examples 1 to 17 of the present invention have an alloy composition within the appropriate range of the present invention, and the area ratio of grains with GROD values ​​measured by the EBSD method in the range of 0° to 5° is 20% to 82%. In this case, they are evaluated as having a tensile strength of 500 MPa or more and a temperature coefficient of resistance (TCR) of 3000 ppm / °C or less in the temperature range from 20°C to 150°C.

[0080] Thus, the copper alloy plates of Examples 1 to 17 of the present invention have high tensile strength and a small temperature coefficient of resistance (TCR).

[0081] In particular, it is believed that, compared with the copper alloy sheet of Example 4 of the present invention, the copper alloy sheet of Example 5 of the present invention has a higher maximum value of partial processing rate in each pass of finishing cold rolling [step 9-1] and a reduced number of finishing heat treatments [step 9-2], thereby further improving tensile strength.

[0082] Furthermore, the copper alloy sheet of Example 6 of the present invention, when heated at 500°C in the second heat treatment step [step 8], can obtain higher tensile strength than the copper alloy sheets of Examples 5 and 7 of the present invention, which are heated at 450°C and 550°C respectively. Therefore, from the viewpoint of obtaining higher tensile strength, it is considered preferable to set the heating temperature in the second heat treatment step [step 8] at around 500°C.

[0083] Furthermore, the copper alloy sheet of Example 8 of the present invention, when the total processing rate in the finishing cold rolling [step 9-1] is 17%, can obtain higher tensile strength than the copper alloy sheet of Example 6 of the present invention with a total processing rate of 13%, and the temperature coefficient of resistance (TCR) is smaller than that of the copper alloy sheet of Example 9 of the present invention with a total processing rate of 38%. Therefore, from the viewpoint of obtaining a copper alloy sheet with a better balance between tensile strength and temperature coefficient of resistance, it is considered preferable to set the total processing rate at around 17%.

[0084] Furthermore, the copper alloy sheet of Example 10 of the present invention, when heated at 300°C in the finishing heat treatment [step 9-2], achieves higher tensile strength than the copper alloy sheet of Example 6 of the present invention, which is heated at 350°C, and the copper alloy sheet of Example 11 of the present invention, which is heated at 400°C. The reason for the sluggish tensile strength of the copper alloy sheets of Examples 6 and 11 of the present invention is believed to be due to the slight softening of the cold-rolled material caused by the high heating temperature in the finishing heat treatment [step 9-2]. Therefore, from the viewpoint of obtaining higher tensile strength, it is considered preferable to set the heating temperature in the finishing heat treatment [step 9-2] to around 300°C.

[0085] Furthermore, the copper alloy sheet of Example 11 of the present invention, when heated at 400°C in the finishing heat treatment [step 9-2], has a smaller temperature coefficient of resistance (TCR) than the copper alloy sheet of Example 6 of the present invention, which was heated at 350°C, and the copper alloy sheet of Example 6 of the present invention, which was heated at 300°C. Therefore, from the viewpoint of obtaining a smaller temperature coefficient of resistance (TCR), it is considered preferable to set the heating temperature in the finishing heat treatment [step 9-2] at around 400°C.

[0086] Furthermore, in the copper alloy plates of Examples 14 and 15 of the present invention, the total content of Ni and Co, the heating temperature in the second heat treatment step [step 8], and the total processing rate in the finishing cold rolling [step 9-1] are all within a good range. Therefore, it is believed that copper alloy plates with better tensile strength and temperature coefficient of resistance can be obtained.

[0087] On the other hand, the copper alloy plates of Comparative Examples 1 to 13 are outside the appropriate range of the present invention in at least one of the alloy composition, tensile strength and GROD value in the range of 0° and 5°, so they are all those whose tensile strength and temperature coefficient of resistance (TCR) or both do not meet the qualified level.

[0088] In particular, the heating temperature of the copper alloy sheet of Comparative Example 1 in the second heat treatment step [step 8] was lower than that of the present invention, so the tensile strength did not reach the qualified level.

[0089] Furthermore, the heating temperature of the copper alloy sheet in Comparative Example 2 in the second heat treatment step [step 8] was higher than the range of the present invention, so the tensile strength did not reach the qualified level.

[0090] Furthermore, the copper alloy plate of Comparative Example 3 had a total Ni and Co content less than that of the present invention, and therefore the temperature coefficient of resistance (TCR) did not meet the acceptable level.

[0091] In addition, the copper alloy sheet of Comparative Example 4 had a Si content less than that of the present invention, so its tensile strength did not reach the qualified level.

[0092] Furthermore, the total processing rate of the copper alloy sheet of Comparative Example 5 in the finishing cold rolling [step 9-1] was lower than that of the present invention, so the tensile strength did not reach the qualified level.

[0093] Furthermore, since the total processing rate of the copper alloy sheet of Comparative Example 6 in the finishing cold rolling [step 9-1] is higher than that of the present invention, the area ratio of grains with GROD values ​​in the range of 0° and 5° is lower than that of the present invention. As a result, the temperature coefficient of resistance (TCR) does not reach the qualified level.

[0094] Furthermore, since the heating temperature of the copper alloy sheet in Comparative Example 7 during the finishing heat treatment [step 9-2] was lower than the range of the present invention, the area ratio of grains with GROD values ​​in the range of 0° and 5° was lower than the range of the present invention. As a result, the temperature coefficient of resistance (TCR) did not reach the qualified level.

[0095] Furthermore, since the heating temperature of the copper alloy sheet of Comparative Example 8 in the finishing heat treatment [step 9-2] was higher than the range of the present invention, the tensile strength did not reach the qualified level.

[0096] Furthermore, since the maximum value of the partial processing rate of the copper alloy sheet of Comparative Example 9 in each pass of the finishing cold rolling [step 9-1] is higher than the range of the present invention, the area ratio of grains with GROD values ​​in the range of 0° and 5° is lower than the range of the present invention, as a result, the temperature coefficient of resistance (TCR) does not reach the qualified level.

[0097] Furthermore, since the maximum value of the partial processing rate of the copper alloy sheet in Comparative Example 10 in each pass of finishing cold rolling [step 9-1] is lower than that of the present invention, the number of finishing heat treatments [step 9-2] is large, and as a result, the tensile strength does not reach the qualified grade.

[0098] Furthermore, since the heating temperature of the copper alloy sheet in Comparative Example 11 in the first heat treatment step [step 6] is lower than the range of the present invention, it is considered that the aging strength cannot be obtained, and as a result, the tensile strength does not reach the qualified level.

[0099] Furthermore, since the heating temperature of the copper alloy sheet in Comparative Example 12 in the first heat treatment step [step 6] is higher than the range of the present invention, it is believed that this resulted in grain roughening, and as a result, the tensile strength did not reach the qualified level.

[0100] In addition, since the heating temperature of the copper alloy sheet of Comparative Example 13 in the first heat treatment step [step 6] is higher than the range of the present invention, the total processing rate in the finishing cold rolling [step 9-1] is lower than the range of the present invention, and the heating temperature in the finishing heat treatment [step 9-2] is higher than the range of the present invention, the area ratio of grains with GROD values ​​in the range of 0° and 5° is higher than the range of the present invention. As a result, the tensile strength does not reach the qualified grade. [Simplified Explanation of the Diagram]

[0017] None [Biomaterial Storage]

[0102] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A copper alloy sheet having the following alloy composition: containing at least one of Ni and Co in a total of 0.50% to 5.00% by mass, Si in a range of 0.10% to 1.50% by mass, and the remainder consisting of Cu and unavoidable impurities; when the GROD value of the aforementioned copper alloy sheet is determined using the EBSD method for a cross-section including the rolling direction and the thickness direction, the area ratio of grains with the aforementioned GROD value in the range of 0° to 5° is in the range of 20% to 82%; the tensile strength is 500 MPa or more and the temperature coefficient of resistance (TCR) in the temperature range from 20°C to 150°C is 3000 ppm / °C or less.

2. The copper alloy sheet as described in claim 1, wherein, The aforementioned alloy composition further contains at least one component selected from the group consisting of Mg, Sn, Zn, P, Cr and Zr, in a total range of more than 0.10% by mass and less than 1.00% by mass.