Copper alloy material, resistor material for resistor, and resistor

Abstract

The invention provides a copper alloy material, a resistor material for a resistor, and a resistor, the copper alloy material having a sufficiently high volume resistivity, a small absolute value of copper thermoelectromotive force and a small absolute value of a temperature coefficient of resistance, and further being capable of suppressing die loss during punching. The copper alloy material has a composition containing 20.0 mass% to 35.0 mass% (inclusive) of Mn and 6.5 mass% to 17.0 mass% (inclusive) of Ni, with the balance made up of Cu and unavoidable impurities, and in a cross section including the extension direction and the thickness direction of the copper alloy material, crystal orientation analysis by the EBSD method is performed, a tilt in a direction parallel to the thickness direction; 111gt, 111gt; the degree of accumulation of the oriented crystal grains is 0.10 or more and less than 1.00.

Description

Technical Field

[0001] The present invention relates to a copper alloy material, a resistance material for a resistor, and a resistor. Background Art

[0002] Hitherto, in order to increase the volume resistivity, a copper alloy added with Mn and Ni at a high concentration has been used as a resistance material.

[0003] For example, Patent Document 1 discloses a resistance alloy for a resistor, particularly for a low-resistance current measurement resistor. The resistance alloy has a copper component, a manganese component having a mass fraction of 23% to 28%, and a nickel component having a mass fraction of 9% to 13%. The mass fraction of the manganese component and the mass fraction of the nickel component are selected such that copper has a low thermal electromotive force of less than ±1 μV / °C in the resistance alloy at 20°C.

[0004] On the other hand, Patent Document 2 discloses an alloy for a resistor body, which is an alloy for a resistor body containing copper, manganese, and nickel, wherein manganese is 33 to 38% by mass and nickel is 8 to 15% by mass.

[0005] [Prior Art Documents]

[0006] (Patent Documents)

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-528376.

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2021-161512. Summary of the Invention

[0009] [Problems to be Solved by the Invention]

[0010] In the case of a copper alloy used for such a resistance material, when Mn and Ni are added at a high concentration, although the characteristics as a resistor body material improve, on the other hand, with solid solution strengthening, the strength and ductility also tend to increase.

[0011] Generally, a resistance material is usually processed into a plate and then subjected to punching by pressing.

[0012] Moreover, a copper alloy highly added with Mn and Ni has high strength and high ductility, so there is a problem that the die is likely to be significantly worn during punching. However, the resistance alloys described in Patent Document 1 and Patent Document 2 do not disclose anything about suppressing the wear of the die that occurs during punching.

[0013] An object of the present invention is to obtain a copper alloy material, a resistance material for a resistor, and a resistor, wherein the copper alloy material has a sufficiently high volume resistivity, a small absolute value of the thermal electromotive force with respect to copper, and a small absolute value of the temperature coefficient of resistance, and further can suppress the wear of the die during punching.

[0014] [Technical means for solving the problem]

[0015] In order to achieve the above object, the main constitution of the present invention is as follows.

[0016] [1] A copper alloy material having the following composition: containing 20.0% by mass or more and 35.0% by mass or less of Mn and 6.5% by mass or more and 17.0% by mass or less of Ni, and the remainder being composed of Cu and unavoidable impurities,

[0017] In a cross-section including the longitudinal direction and the thickness direction of the copper alloy material, when performing crystal orientation analysis by the EBSD method, the cumulative degree of grains having a <111> orientation in the direction parallel to the thickness direction is 0.10 or more and less than 1.00.

[0018] [2] The copper alloy material according to [1], wherein the cumulative degree of grains having a <111> orientation in the direction parallel to the thickness direction is 0.20 or more.

[0019] [3] The copper alloy material according to [1] or [2], wherein the composition further contains at least one of 0.01% by mass or more and 0.50% by mass or less of Fe and 0.01% by mass or more and 2.00% by mass or less of Co.

[0020] [4] The copper alloy material according to any one of [1] to [3] above, wherein the composition further contains at least one selected from the group consisting of the following components:

[0021] 0.01% by mass or more and 3.00% by mass or less of Sn,

[0022] 0.01% by mass or more and 5.00% by mass or less of Zn,

[0023] 0.01% by mass or more and 0.50% by mass or less of Cr,

[0024] 0.01% by mass or more and 0.50% by mass or less of Ag,

[0025] 0.01% by mass or more and 1.00% by mass or less of Al,

[0026] 0.01% by mass or more and 0.50% by mass or less of Mg,

[0027] Si of 0.01 mass% or more and 0.50 mass% or less and

[0028] P of 0.01 mass% or more and 0.50 mass% or less.

[0029] [5] A resistive material for a resistor, which is composed of the copper alloy material according to any one of the above [1] to [4].

[0030] [6] A resistor, which is a shunt resistor or a chip resistor, and the resistor has the resistive material for a resistor according to the above [5].

[0031] [Effects of the Invention]

[0032] According to the present invention, a copper alloy material, a resistive material for a resistor, and a resistor can be obtained. The copper alloy material has, as a prerequisite, characteristics required for a resistive material (for example, characteristics of sufficiently high volume resistivity, small absolute value of the thermal electromotive force with respect to copper, and small absolute value of the resistance temperature coefficient), and further can effectively suppress the wear of the die during punching. Description of the Drawings

[0033] FIG. 1 is a perspective view schematically showing a cut surface (machined surface) of the copper alloy material after stamping the copper alloy material of the present invention.

[0034] FIG. 2 is a schematic view for explaining a method of obtaining the thermal electromotive force (EMF) with respect to copper for each test material of the example and the comparative example of the present invention. Detailed Description of the Invention

[0035] The inventors found that by setting the composition of the copper alloy material within a specified range and having, as a prerequisite, characteristics required for a resistive material (for example, characteristics of sufficiently high volume resistivity, small absolute value of the thermal electromotive force with respect to copper, and small absolute value of the resistance temperature coefficient), and further controlling the crystal orientation by managing the manufacturing steps of the copper alloy material. As a result, breakage is likely to occur during processing in the direction parallel to the thickness direction of the copper alloy material, and a copper alloy material, a resistive material for a resistor, and a resistor can be provided. The copper alloy material can effectively suppress the wear of the die, and the present invention was completed based on the above findings.

[0036] Hereinafter, embodiments of the present invention will be described.

[0037] [1] Composition of the Copper Alloy Material

[0038] <Necessary Constituent Elements>

[0039] The copper alloy material of the present invention contains, as necessary constituent elements: Mn of 20.0 mass% or more and 35.0 mass% or less, and Ni of 6.5 mass% or more and 17.0 mass% or less.

[0040] [Mn: 20.0 mass% or more and 35.0 mass% or less]

[0041] Mn (manganese) is an element that can increase the volume resistivity ρ. In order to exert this effect and obtain a homogeneous copper alloy material, it contains 20.0 mass% or more of Mn, preferably 22.0 mass% or more, and more preferably 24.0 mass% or more. Here, by increasing the Mn content to 22.0 mass% or more or 24.0 mass% or more, the volume resistivity ρ of the copper alloy material can be further increased. On the other hand, if the Mn content exceeds 35.0 mass%, the melting point of the copper alloy material will decrease, making it difficult to manufacture the copper alloy material, especially to control hot working, and it is difficult to obtain uniform properties. In addition, if the Mn content exceeds 35.0 mass%, the absolute value of the copper thermal electromotive force (EMF) will easily become a large negative number. Therefore, the Mn content is set in the range of 20.0 mass% or more and 35.0 mass% or less, preferably in the range of 22.0 mass% or more and 35.0 mass% or less, and more preferably in the range of 24.0 mass% or more and 35.0 mass% or less.

[0042] [Ni: 6.5 mass% or more and 17.0 mass% or less]

[0043] Ni (nickel) is an element that can adjust the copper thermal electromotive force (EMF) in the positive direction. Therefore, by adding Ni in addition to Mn which has a tendency for the copper thermal electromotive force (EMF) to be negative, the absolute value of the copper thermal electromotive force (EMF) can be reduced. In order to exert this effect, it is preferably to contain 6.5 mass% or more of Ni. On the other hand, if the Ni content exceeds 17.0 mass%, it becomes difficult to obtain a uniform metal structure, and the volume resistivity ρ and the copper thermal electromotive force (EMF), etc. may change depending on the part of the copper alloy material. In addition, if the Ni content exceeds 17.0 mass%, the copper thermal electromotive force (EMF) will easily become a large positive number, and in addition, the absolute value of the resistance temperature coefficient (TCR) will easily become larger. Therefore, from the viewpoint of obtaining a copper alloy material with desired properties or from the viewpoint of obtaining a copper alloy material that is easy to manufacture, the Ni content is set in the range of 6.5 mass% or more and 17.0 mass% or less, preferably in the range of 6.5 mass% or more and 12.0 mass% or less, and more preferably in the range of 6.5 mass% or more and 9.0 mass% or less.

[0044] <Optional additive components>

[0045] The copper alloy material of the present invention may contain the following components as optional additive components.

[0046] [At least one of Fe of 0.01% by mass or more and 0.50% by mass or less and Co of 0.01% by mass or more and 2.00% by mass or less]

[0047] Preferably, the copper alloy material of the present invention further contains at least one of Fe of 0.01% by mass or more and 0.50% by mass or less and Co of 0.01% by mass or more and 2.00% by mass or less. Thus, by further containing one or both of Fe and Co, the absolute value of the thermal electromotive force (EMF) against copper can be reduced.

[0048] (Fe: 0.01% by mass or more and 0.50% by mass or less)

[0049] Fe (iron) is an element that can adjust the thermal electromotive force (EMF) against copper in the positive direction. To exert this effect, it is preferable to contain Fe of 0.01% by mass or more. On the other hand, if the content of Fe exceeds 0.50% by mass, it becomes difficult to obtain a uniform metal structure, resulting in easy deviation of electrical properties. Therefore, the content of Fe is preferably set in the range of 0.01% by mass or more and 0.50% by mass or less. In addition, from other viewpoints, Fe is an inexpensive element, but on the other hand, it is also an element that causes large fluctuations in electrical characteristics when used over a long period of time. Therefore, from the viewpoint of further improving the stability of electrical characteristics such as heat and thereby further improving the reliability when used as a resistance material or the like over a long period of time, it is not desirable to contain a large amount. Therefore, the content of Fe is preferably set at 0.50% by mass or less, more preferably at 0.30% by mass or less, and further preferably at 0.20% by mass or less. In particular, from the viewpoint of further improving the reliability when used over a long period of time, it is preferable to contain Co rather than Fe. That is, it is preferable to contain Co described below as necessary and not to contain Fe.

[0050] (Co: 0.01% by mass or more and 2.00% by mass or less)

[0051] Co (cobalt) is an element that can adjust the thermal electromotive force (EMF) against copper in the positive direction. To exert this effect, it is preferable to contain Co of 0.01% by mass or more. On the other hand, if the content of Co exceeds 2.00% by mass, it becomes difficult to obtain a uniform metal structure, resulting in easy deviation of electrical properties. Therefore, the content of Co is preferably set in the range of 0.01% by mass or more and 2.00% by mass or less. Co is an expensive element, but different from Fe, as long as it is within the range of 2.00% by mass or less, it has the advantage that electrical characteristics are not easily changed over time.

[0052] [Other optional additive components]

[0053] The copper alloy material of the present invention, as any additional component other than Fe and Co, preferably further contains at least one selected from the group consisting of the following components: Sn of 0.01% by mass or more and 3.00% by mass or less, Zn of 0.01% by mass or more and 5.00% by mass or less, Cr of 0.01% by mass or more and 0.50% by mass or less, Ag of 0.01% by mass or more and 0.50% by mass or less, Al of 0.01% by mass or more and 1.00% by mass or less, Mg of 0.01% by mass or more and 0.50% by mass or less, Si of 0.01% by mass or more and 0.50% by mass or less, and P of 0.01% by mass or more and 0.50% by mass or less. Thereby, the volume resistivity ρ of the copper alloy material can be further improved.

[0054] (Sn: 0.01% by mass or more and 3.00% by mass or less)

[0055] Sn (tin) is a component that can be used to adjust the volume resistivity ρ. To exert this effect, it is preferable to contain Sn of 0.01% by mass or more. On the other hand, by setting the Sn content to 3.00% by mass or less, it is possible to make it less likely to occur that the manufacturability is reduced due to the embrittlement of the copper alloy material.

[0056] (Zn: 0.01% by mass or more and 5.00% by mass or less)

[0057] Zn (zinc) is a component that can be used to adjust the volume resistivity ρ. To exert this effect, it is preferable to contain Zn of 0.01% by mass or more. On the other hand, if the Zn content is too high, it may have an adverse effect on the stability of the electrical properties of the resistor such as the volume resistivity ρ, the resistance temperature coefficient (TCR), and the thermal electromotive force (EMF) with respect to copper. Therefore, it is preferably set to 5.00% by mass or less.

[0058] (Cr: 0.01% by mass or more and 0.50% by mass or less)

[0059] Cr (chromium) is a component that can be used to adjust the volume resistivity ρ. To exert this effect, it is preferable to contain Cr of 0.01% by mass or more. On the other hand, if the Cr content is too high, it may have an adverse effect on the stability of the electrical properties of the resistor such as the volume resistivity ρ, the resistance temperature coefficient (TCR), and the thermal electromotive force (EMF) with respect to copper. Therefore, it is preferably set to 0.50% by mass or less.

[0060] (Ag: 0.01% by mass or more and 0.50% by mass or less)

[0061] Ag (silver) is a component that can be used to adjust the volume resistivity ρ. To play this role, it is preferably to contain 0.01 mass% or more of Ag. On the other hand, if the Ag content is too high, since it may have an adverse effect on the stability of the electrical properties of the resistor such as the volume resistivity ρ, the resistance temperature coefficient (TCR), and the thermal electromotive force against copper (EMF), it is preferably set to 0.50 mass% or less.

[0062] (Al: 0.01 mass% or more and 1.00 mass% or less)

[0063] Al (aluminum) is a component that can be used to adjust the volume resistivity ρ. To play this role, it is preferably to contain 0.01 mass% or more of Al. On the other hand, if the Al content is too high, since it may embrittle the copper alloy material, it is preferably set to 1.00 mass% or less.

[0064] (Mg: 0.01 mass% or more and 0.50 mass% or less)

[0065] Mg (magnesium) is a component that can be used to adjust the volume resistivity ρ. To play this role, it is preferably to contain 0.01 mass% or more of Mg. On the other hand, if the Mg content is too high, since it may embrittle the copper alloy material, it is preferably set to 0.50 mass% or less.

[0066] (Si: 0.01 mass% or more and 0.50 mass% or less)

[0067] Si (silicon) is a component that can be used to adjust the volume resistivity ρ. To play this role, it is preferably to contain 0.01 mass% or more of Si. On the other hand, if the Si content is too high, since it may embrittle the copper alloy material, it is preferably set to 0.50 mass% or less.

[0068] (P: 0.01 mass% or more and 0.50 mass% or less)

[0069] P (phosphorus) is a component that can be used to adjust the volume resistivity ρ. To play this role, it is preferably to contain 0.01 mass% or more of P. On the other hand, if the P content is too high, since it may embrittle the copper alloy material, it is preferably set to 0.50 mass% or less.

[0070] (Sn, Zn, Cr, Ag, Al, Mg, Si and P: the total is 0.01 mass% or more and 5.00 mass% or less)

[0071] In order to achieve the above effects, it is preferable that the total content of Sn, Zn, Cr, Ag, Al, Mg, Si and P is 0.01% by mass or more. On the other hand, if these components are contained in a large amount, embrittlement may occur due to damage to the uniformity of the metal structure. Therefore, it is preferable that the total is 5.00% by mass or less.

[0072] <The balance: Cu and unavoidable impurities>

[0073] In addition to the above-mentioned essential components and optional additive components, the balance is composed of Cu (copper) and unavoidable impurities. In addition, the so-called "unavoidable impurities" referred to herein mean impurities that are substantially present in raw materials in copper-based products or are unavoidably mixed in during the manufacturing process and are originally unnecessary, but are tolerable because they are in trace amounts and do not adversely affect the characteristics of copper-based products. Examples of components that can be cited as unavoidable impurities include non-metallic elements such as sulfur (S) and oxygen (O), and metallic elements such as antimony (Sb). In addition, the upper limit of the content of these components is preferably set to 0.05% by mass for each of the above components, and preferably 0.10% by mass in total for the above components.

[0074] [2] Metal Structure and Shape of Copper Alloy Material

[0075] [Metal Structure of Copper Alloy Material]

[0076] In the cross-section including the longitudinal direction and the thickness direction of the copper alloy material of the present invention, the cumulative degree of grains having a <111> orientation in the direction parallel to the thickness direction is 0.10 or more and less than 1.00 as determined by EBSD method.

[0077] In a copper alloy material with a high content of Mn and Ni, the β-orientation group tends to be dominant. As a result, there is a tendency that the grains having a <111> orientation in the direction parallel to the thickness direction of the copper alloy material decrease and are in a state of being almost absent. When punching is performed using a pressing die or the like, the copper alloy material is processed in the thickness direction from the surface side. However, since there are almost no grains having a <111> orientation in the thickness direction that becomes the starting point of fracture, it is not easy to cause damage to the copper alloy material during punching, that is, it is not easy to form a fracture surface. Therefore, the contact time of the copper alloy material with the die becomes longer, resulting in a larger wear of the die, and thus the service life of the die becomes shorter. In addition, when damage is not likely to occur, the proportion of the fracture surface 5 in the cut surface 2 becomes smaller, and the ratio of the shear surface 4 becomes larger (see Fig. 1).

[0078] In the copper alloy material of the present invention, by controlling the manufacturing method as described above, the grains having a <111> orientation in the direction parallel to the thickness direction are increased (accumulated). Thus, during punching, it becomes easier to break the copper alloy material, that is, fracture is likely to occur. Therefore, by shortening the contact time between the copper alloy material and the die, wear of the die can be suppressed, and as a result, the service life of the die can be increased. When it is easy to cause damage to the copper alloy material, at the cut surface 2, the ratio of the fracture surface 5 becomes larger and the ratio of the shear surface 4 becomes smaller. From the viewpoint of making the copper alloy material easily broken during punching and suppressing die wear, the degree of accumulation of grains having a <111> orientation in the direction parallel to the thickness direction of the copper alloy material needs to be 0.10 or more, preferably 0.20 or more. In the copper alloy material of the present invention, from the tendency that the β orientation group is likely to become dominant due to the large contents of Mn and Ni, it is difficult to make the degree of accumulation of grains having a <111> orientation in the direction parallel to the thickness direction of the copper alloy material 1.00 or more. Therefore, the upper limit of the degree of accumulation of grains having a <111> orientation in the direction parallel to the thickness direction is set to be less than 1.00.

[0079] The crystal orientation analysis data by the SEM-EBSD method can be obtained, for example, from the following crystal orientation analysis data. The crystal orientation data is continuously measured using an EBSD detector (manufactured by TSL Co., Ltd., OIM5.0 HIKARI) attached to a high-resolution scanning analytical electron microscope (manufactured by JEOL Ltd., JSM-7001FA), and then the measured crystal orientation data is calculated (processed) using analysis software (manufactured by TSL Co., Ltd., OIM Analysis). The so-called "EBSD" is an abbreviation of Electron BackScatter Diffraction, which means a crystal orientation analysis technique using the diffraction of backscattered electron Kikuchi lines generated when an electron beam is irradiated onto an aluminum-based wire as a measurement sample in a scanning electron microscope (SEM). The measurement object is the surface of the copper alloy material polished to a mirror surface by polishing, and the measurement area is, for example, 0.1 mm 2As described above, the measurement is performed, for example, with a step size of 0.5 μm. Using analysis software called OIM ANALYSIS, the harmonic series expansion is used, the series rank is set to 16, the half-width when fitting a Gaussian distribution is set to 5°, and the sample symmetry is set to orthotropic for the calculation. From the obtained texture, an inverse pole figure in the direction parallel to the thickness direction of the copper alloy material is plotted, and thus the cumulative degree of grains with a <111> orientation can be obtained.

[0080] [Shape of the copper alloy material]

[0081] The shape of the copper alloy material of the present invention is not particularly limited. However, from the viewpoint of facilitating subsequent processing steps such as hot working or cold working, and cutting processing such as stamping, a sheet material is preferred. Here, for a copper alloy material formed by rolling such as a sheet material, the rolling direction can be set as the elongation direction. On the other hand, the copper alloy material of the present invention can be a square wire, a strip, a bar, etc. By forming these shapes using the copper alloy material of the present invention, it becomes easier to perform cutting processing for the ends. Here, for these shaped copper alloy materials formed by wire drawing, drawing, or extrusion, any one of the wire drawing direction, the drawing direction, and the extrusion direction can be set as the elongation direction.

[0082] [3] Manufacturing method of the copper alloy material

[0083] As an example of the manufacturing process for obtaining the above copper alloy material, the following method can be cited. The following manufacturing method can be applied not only to sheet materials but also to the end treatment of square wires.

[0084] As an example of the manufacturing method of the copper alloy material of the present invention, a copper alloy raw material having an alloy composition substantially the same as that of the above copper alloy material is subjected to at least a casting step, a homogenization heat treatment step, a hot working (elongation) step, a cold working step, a first annealing step, and a second annealing step in sequence. Thereby, the copper alloy material of the present invention can be obtained, that is, a copper alloy material in which the cumulative degree of grains with a <111> orientation in the direction parallel to the thickness direction is in the range of 0.10 or more and less than 1.00. In addition, by repeating the cycle of the cold working step, the first annealing step, and the second annealing step one or more times, it is possible to maintain the cumulative <111> orientation in the direction parallel to the thickness direction and to progress the processing of the copper alloy material.

[0085] [Casting step]

[0086] The casting step is to use a high-frequency melting furnace to melt the copper alloy raw material with the above alloy composition in an inert gas atmosphere or in a vacuum, and then cast it to form an ingot of a specific shape (for example, thickness 30 mm to 300 mm, width 500 mm, length 3000 mm). In addition, the alloy composition of the copper alloy raw material may not always be exactly the same as the alloy composition of the copper alloy sheet produced due to the adhesion or volatilization of the added components in the melting furnace during each manufacturing step, but it still has an alloy composition substantially the same as that of the copper alloy material.

[0087] [Homogenization heat treatment step]

[0088] The homogenization heat treatment step is as follows: performing heat treatment for homogenization on the ingot after the casting step. Here, from the viewpoint of suppressing the coarsening of crystal grains, the heat treatment conditions in the homogenization heat treatment step are preferably such that the heating temperature is in the range of 750 °C or higher and 900 °C or lower, and the heat treatment time is in the range of 10 minutes or longer and 10 hours or shorter.

[0089] The homogenization heat treatment step can be carried out, for example, by using a known method such as batch heat treatment, high-frequency heating, current heating, continuous heat treatment such as in-transit heating, etc.

[0090] [Hot working step]

[0091] The hot working step is as follows: performing rolling, stretching and other stretching processes on the ingot that has undergone the homogenization heat treatment step under heating until it reaches a specific thickness to form a hot-rolled material. The conditions of the hot working step are preferably such that the heating temperature is in the range of 750 °C or higher and 900 °C or lower, and it can be the same as the heating temperature in the homogenization heat treatment step. In addition, from the viewpoint of obtaining a uniform metal structure, the processing rate in the hot working step is preferably 50% or higher and 99% or lower.

[0092] Here, the "processing rate" is a value obtained by subtracting the cross-sectional area after processing from the cross-sectional area before performing processes such as rolling and stretching, dividing the result by the cross-sectional area before processing, and multiplying by 100 to express it as a percentage, and can be represented by the following formula.

[0093] [Processing rate] = {([Cross-sectional area before processing] - [Cross-sectional area after processing]) / [Cross-sectional area before processing]} × 100

[0094] The hot working step can be carried out, for example, by using a known method using rolling rolls, etc. The hot working step can be carried out once, or can be carried out multiple times until the target thickness is obtained.

[0095] The hot-rolled material in the hot working step is preferably cooled. Here, the means for cooling the hot-rolled material is not particularly limited. From the viewpoint of, for example, making it difficult for grain coarsening to occur, the means for increasing the cooling rate as much as possible is preferred, and for example, the cooling rate is preferably set to 50 °C / second or more by means such as water cooling.

[0096] Here, surface cutting for removing the surface can be performed on the cooled hot-rolled material. By performing surface cutting, the surface oxide film and defects generated in the hot working step can be removed. The conditions for surface cutting can be the generally practiced conditions and are not particularly limited. The amount removed from the surface of the hot-rolled material by surface cutting can be appropriately set based on the conditions of the hot working step, and can be, for example, about 0.5 mm to 4.0 mm from the surface of the hot-rolled material.

[0097] [Cold working step]

[0098] The cold working step is a step in which the hot-rolled material after the hot working step is subjected to processing such as stretching and rolling under cooling under the conditions of a processing rate of 40% or more and 65% or less. If the processing rate is less than 40%, the driving force for recrystallization will be insufficient and it will tend to be difficult to obtain a uniform metal structure. On the other hand, if the processing rate exceeds 65%, the degree of accumulation of grains having a <111> orientation in the direction parallel to the thickness direction may decrease. In particular, from the viewpoint of preventing the degree of accumulation of grains having a <111> orientation in the direction parallel to the thickness direction from decreasing due to the cold working step, when performing multiple cold working steps, it is preferred that the processing rate after the second time is 60% or less.

[0099] The cold working step can be performed, for example, by a known method using rolling rolls or the like. The cold working step can be performed once, or can be performed multiple times until the target thickness is obtained.

[0100] [First annealing step]

[0101] The first annealing step is as follows: a heat treatment is performed on the cold-rolled material after the cold working step to adjust the strain of the crystal grains. Here, the conditions of the heat treatment in the first annealing step are: the heating temperature is in the range of above 300°C and below 400°C, and the annealing time is in the range of above 60 minutes and below 180 minutes. By performing the first annealing step under the conditions of the above range, the strain can be adjusted. Therefore, after performing the subsequent second annealing step, a large number of crystal nuclei of crystal grains with a <111> orientation in the direction parallel to the thickness direction can be formed, and as a result, the accumulation degree of crystal grains with a <111> orientation in the direction parallel to the thickness direction can be improved. If the heating temperature in the first annealing step is less than 300°C, the strain cannot be adjusted. On the other hand, if the heating temperature exceeds 400°C, the strain will become too small, resulting in insufficient driving force for recrystallization.

[0102] The first annealing step can be performed, for example, by using a conventional method, such as batch heat treatment, high-frequency heating, current heating, continuous heat treatment such as in-transit heating, etc.

[0103] [Second annealing step]

[0104] The second annealing step is an annealing step as follows: a heat treatment is performed on the sheet material with adjusted strain after the first annealing step to cause it to recrystallize. Here, the conditions of the heat treatment in the second annealing step are: the heating temperature is in the range of above 600°C and below 800°C, and the annealing time is in the range of above 1 minute and below 120 minutes.

[0105] The second annealing step can be performed, for example, by using a conventional method, such as batch heat treatment, high-frequency heating, current heating, continuous heat treatment such as in-transit heating, etc.

[0106] The copper alloy material after the second annealing step can obtain a sheet material or the like with a target thickness in a state where the accumulation degree of crystal grains with a <111> orientation in the direction parallel to the thickness direction is maintained within a desired range by performing one or more cycles of the above cold working step, first annealing step, and second annealing step until the target thickness is reached.

[0107] [4] Use of the copper alloy material

[0108] The copper alloy material of the present invention is a copper alloy material having a sufficiently high volume resistivity, a small absolute value of the thermal electromotive force with respect to copper, and a small absolute value of the temperature coefficient of resistance. Furthermore, the loss of the die during punching can be suppressed, so it is extremely useful as a resistance material for resistors. The resistance material for resistors of the present invention can be used for resistors, preferably shunt resistors or chip resistors.

[0109] The above has described the embodiments of the present invention. However, the present invention is not limited to the above embodiments and also includes all aspects within the concept of the present invention and the scope of the patent application for the invention, and various changes can be made within the scope of the present invention.

[0110] [Examples]

[0111] Subsequently, examples and comparative examples will be described. However, the present invention is not limited to these examples.

[0112] (1) Experiment 1: Manufacture and evaluation of copper alloy materials

[0113] Copper alloy materials of Examples 1 to 17 and Comparative Examples 1 to 6 were manufactured from copper alloy raw materials having the compositions shown in Table 1, and their properties were tested. In addition, in Table 1, when the content of a component is less than 0.001% by mass, it is at the level of unavoidable impurities, so it is regarded as not containing the component and is recorded as "-" in the table.

[0114] (Examples 1 to 17)

[0115] The copper alloy raw materials having the compositions shown in Table 1 were melted and cast to obtain ingots with a thickness of 30 mm. Subsequently, after homogenization heat treatment at 800°C for 5 hours, at the same temperature, a hot working step (hot rolling) was performed starting from a thickness of 30 mm until it became 10 mm, and then the surface oxide film was removed by face cutting 1 mm from each of the two surfaces to make the thickness 8 mm. After that, a cycle of cold working step (cold rolling), first annealing step, and second annealing step was performed 4 times under the conditions shown in Table 2 to obtain the copper alloy materials of Examples 1 to 17.

[0116] (Comparative Examples 1, 2, 4)

[0117] The copper alloy raw materials having the compositions shown in Table 1 were melted and cast to obtain ingots with a thickness of 30 mm. Subsequently, after homogenization heat treatment at 800°C for 5 hours, at the same temperature, a hot working step (hot rolling) was performed starting from a thickness of 30 mm until it became 10 mm, and then the surface oxide film was removed by face cutting 1 mm from each of the two surfaces to make the thickness 8 mm. After that, a cycle of cold working step (cold rolling) and second annealing step was performed 3 or 4 times under the conditions shown in Table 2 to obtain the copper alloy materials of Comparative Examples 1, 2, and 4. The first annealing step was not performed in Comparative Examples 1, 2, and 4.

[0118] (Comparative Examples 3, 5, 6)

[0119] A copper alloy raw material having the composition shown in Table 1 was melted and cast to obtain an ingot with a thickness of 30 mm. Subsequently, after homogenization heat treatment at 800 °C for 5 hours, at the same temperature, a hot working step (hot rolling) was performed starting from a thickness of 30 mm until it became 10 mm, and then the surface oxide film was removed by face cutting 1 mm from each of the two side surfaces to make the thickness 8 mm. After that, under the conditions shown in Table 2, a cycle of cold working step (cold rolling), first annealing step, and second annealing step was performed 4 times to obtain the copper alloy materials of Comparative Examples 3, 5, and 6.

[0120] [Table 1]

[0121]

[0122] [Table 2]

[0123]

[0124] [Various measurement and evaluation methods]

[0125] Using the copper alloy materials (test materials) of the above Examples 1 to 17 and Comparative Examples 1 to 6, the following property evaluations were performed. The evaluation conditions for each property are as follows.

[0126] [1] Cumulative degree of grains having a <111> orientation in the direction parallel to the thickness direction

[0127] The crystal orientation analysis data by the SEM-EBSD method can be obtained from the crystal orientation analysis data calculated (processed) in the following manner: After mirror-polishing the cross-section parallel to the rolling direction of the copper alloy sheet to prepare a cross-section specimen, the crystal orientation data is continuously measured using an EBSD detector (OIM5.0 HIKARI manufactured by TSL Co., Ltd.) attached to a high-resolution scanning analytical electron microscope (JSM-7001FA manufactured by JEOL Ltd.), and then the measured crystal orientation data is calculated (processed) using analysis software (OIM Analysis manufactured by TSL Co., Ltd.). The area to be measured in the EBSD measurement is set to a total of 0.1 mm 2Above, the step size during measurement was set to 0.5 μm. Based on the measurement results obtained by EBSD, using analysis software called OIM ANALYSIS, with the Harmonic Series Expansion, the Series Rank was set to 16, the Gaussian Half-Width when fitting the Gaussian distribution was set to 5°, and the Sample Symmetry was set to Orthotropic for calculation. From the obtained Texture, an inverse pole figure showing the intensity distribution of crystal orientations was obtained. The inverse pole figure in the direction parallel to the thickness direction was plotted to obtain the cumulative degree of grains with a <111> orientation. The cumulative degree obtained at this time has the random state set to 1, and the larger the number, the more strongly oriented to this orientation. That is, when the cumulative degree is less than 1, it means that the number of grains oriented to this orientation is less than the random state.

[0128] [2] Evaluation of stamping processability

[0129] In this evaluation, the stamping processability (ease of fracture) of the copper alloy material was evaluated by measuring the ratio of the fracture surface to the cut surface after stamping.

[0130] The stamping processability of the produced copper alloy material was carried out according to the shear test method described in the Technical Standard JCBA T310:2019 of the Japan Copper Development Association for copper and copper alloy sheet strips. That is, the gap between the upper die (punch) and the lower die (die) was adjusted to be 10 μm, and the copper alloy material was punched to form a rectangular shape with a size of 2 mm along the extending direction y and 10 mm along the direction intersecting the extending direction y at a right angle (the x direction in Figure 1) to produce a test material of the copper alloy material 10 with a cut surface 2 on the outer edge.

[0131] Figure 1 is a schematic diagram showing the cut surface during stamping of the copper alloy material of the present invention. The copper alloy material 10 shown in Figure 1 shows the cut surface 2 after stamping, and the stamping is carried out by lowering the upper die (punch) while being fixed on the lower die (die) (not shown). Here, the cut surface 2 is sequentially formed with a corner break 3, a shear surface 4, and a fracture surface 5 from the top surface 10a side of the copper alloy material 10 after stamping. Also, a burr is mostly formed at the lower edge of the cut surface 2 extending outward from the fracture surface 5. In addition, a boundary line 7 is formed at the boundary between the shear surface 4 and the fracture surface 5.

[0132] In this evaluation, for the surface in the formed cut surface 2 along the direction (x direction in Figure 1) intersecting at a right angle with the extending direction y, observation was carried out at a magnification of 200 times using a scanning electron microscope (SEM) (SSX-550 manufactured by Shimadzu Corporation). Then, based on the scanning electron microscope (SEM) photograph of the cut surface 2, the gap between the burr tip 6 and the linear fracture surface that becomes the shear surface 4 was set as the fracture surface 5, and then the length of the cross-section was measured. The measurement was carried out at three locations in the cut surface, and the average value of the three locations was set as the length t3 of the fracture surface. Then, the ratio of the length t3 of the fracture surface to the thickness t of the copper alloy material was calculated, thereby obtaining the ratio of the fracture surface in the cut surface. When the ratio of this fracture surface is 50% or more, it is regarded as excellent and evaluated as "◎". In addition, when the ratio of this fracture surface is 40% or more and less than 50%, it is regarded as good and evaluated as "〇". On the other hand, when the ratio of this fracture surface is less than 40%, it is regarded as poor and evaluated as "×". The results are shown in Table 3. all For the ratio of the fracture surface to the thickness t of the copper alloy material, the ratio of the fracture surface in the cut surface was obtained. When the ratio of this fracture surface is 50% or more, it is regarded as excellent and evaluated as "◎". In addition, when the ratio of this fracture surface is 40% or more and less than 50%, it is regarded as good and evaluated as "〇". On the other hand, when the ratio of this fracture surface is less than 40%, it is regarded as poor and evaluated as "×". The results are shown in Table 3.

[0133] [3] Measurement of volume resistivity

[0134] For the manufactured copper alloy material, the obtained plate with a thickness of 0.3 mm was cut into a width of 10 mm and a length of 300 mm to prepare a test material.

[0135] The measurement of the volume resistivity ρ was carried out by setting the distance between the voltage terminals to 200 mm, setting the measurement current to 100 mA, and measuring the voltage at room temperature of 20°C by the four-terminal method according to the method specified in Japanese Industrial Standard JIS C2525, and the volume resistivity ρ [μΩ·cm] was obtained from the measured value.

[0136] For the measured volume resistivity ρ, when it is 80 μΩ·cm or more, it is regarded as having a sufficiently large volume resistivity ρ and being excellent as a resistance material, and evaluated as "◎". In addition, when the volume resistivity ρ is 70 μΩ·cm or more and less than 80 μΩ·cm, it is regarded as having a large volume resistivity ρ and being good as a resistance material, and evaluated as "〇". On the other hand, when the volume resistivity ρ is less than 70 μΩ·cm, it is regarded as having a small volume resistivity ρ and having poor characteristics as a resistance material, and evaluated as "×". In this example, "◎" and "〇" were evaluated as the qualified grades. The results are shown in Table 3.

[0137] [4] Measurement method of thermoelectromotive force (EMF) against copper

[0138] For the manufactured copper alloy material, the obtained plate with a thickness of 0.3 mm was cut into a width of 10 mm and a length of 1000 mm to prepare a test material.

[0139] The measurement of the thermal electromotive force (EMF) of the test material against copper is carried out in accordance with Japanese Industrial Standard JIS C2527. More specifically, as shown in Fig. 2, for the measurement of the thermal electromotive force (EMF) of the test material 11 against copper, a pure copper wire with a diameter of 1 mm or less that has been fully annealed is used as the standard copper wire 21. The temperature measurement contact point P1 where one end of the test material 11 and the standard copper wire 21 are connected is immersed in warm water that has been kept warm in a constant temperature bath 41 at 80 °C, and the reference contact points P 21 , P 22 where the other ends of the test material 11 and the standard copper wire 21 are respectively connected to copper wires 31 and 32 are immersed in ice water at 0 °C that has been kept cold in an ice point device 42, and then a voltage measuring device 43 is used to measure the electromotive force at this time. For the obtained electromotive force, it is divided by the temperature difference, that is, 80 [°C], to obtain the thermal electromotive force (EMF) (μV / °C) against copper.

[0140] Regarding the measured thermal electromotive force (EMF) against copper, when the absolute value is 0.5 μV / °C or less, it is regarded as having a small absolute value of the thermal electromotive force (EMF) and excellent characteristics as a resistance material, and is evaluated as "◎". In addition, when the absolute value exceeds 0.5 μV / °C and is 1.0 μV / °C or less, it is regarded as having good characteristics as a resistance material and is evaluated as "○". On the other hand, when the absolute value of the thermal electromotive force (EMF) is greater than 1.0 μV / °C, it is regarded as having a large absolute value of the thermal electromotive force (EMF) and poor characteristics as a resistance material, and is evaluated as "×". The results are shown in Table 3.

[0141] [5] Method for measuring the temperature coefficient of resistance (TCR)

[0142] For the fabricated copper alloy material, a sheet with a thickness of 0.3 mm is cut into a width of 10 mm and a length of 300 mm to make a test material.

[0143] The measurement of the temperature coefficient of resistance (TCR) is carried out by setting the distance between the voltage terminals to 200 mm and the measurement current to 100 mA. By the four-terminal method according to the methods specified in Japanese Industrial Standards JIS C2525 and JIS C2526, the voltage when the test material is heated to 150 °C is measured, and the resistance value R 150℃ [μΩ] at 150 °C is obtained from the obtained value. Subsequently, the voltage when the temperature of the test material is cooled to 20 °C is measured, and the resistance value R 20℃ [μΩ] at 20 °C is obtained from the obtained value. And, based on R 150℃ and R 20℃ as the obtained values, according to the formula TCR = {(R 150℃[μΩ] - R 20℃ [μΩ]) / R 20℃ [μΩ]} × {1 / (150[°C] - 20[°C])} × 106, calculate the temperature coefficient of resistance (ppm / °C).

[0144] Regarding the measured temperature coefficient of resistance (TCR), when the absolute value is 50 ppm / °C or less, it is regarded as the absolute value of the temperature coefficient of resistance (TCR) being sufficiently small and the resistance material being excellent, and it is evaluated as "◎". In addition, when the absolute value is more than 50 ppm / °C and 60 ppm / °C or less, it is evaluated as "○". On the other hand, when the absolute value of the temperature coefficient of resistance (TCR) is greater than 60 ppm / °C, it is regarded as the absolute value of the temperature coefficient of resistance (TCR) being large and the characteristics of the resistance material being poor, and it is evaluated as "×". The results are shown in Table 3.

[0145] [6] Comprehensive evaluation

[0146] Among the five evaluation results of stamping processability, volume resistivity ρ, thermal electromotive force (EMF) against copper, and evaluation of the temperature coefficient of resistance (TCR), when all four characteristics are evaluated as "◎", it is regarded as all characteristics being excellent and evaluated as "◎". In addition, when there is no "×" among these four evaluation results and at least one is evaluated as "○", it is regarded as at least these four characteristics being good and evaluated as "○". On the other hand, when at least one of the evaluation results of stamping processability, volume resistivity ρ, thermal electromotive force (EMF) against copper, and temperature coefficient of resistance (TCR) is "×", it is regarded as at least one of these four characteristics being unqualified and evaluated as "×". The results are shown in Table 3.

[0147] [Table 3]

[0148]

[0149] As shown in Tables 1 to 3, for the copper alloy materials of Examples 1 to 17 having a specific composition and with the cumulative degree of <111>-oriented grains in the direction parallel to the thickness direction being 0.10 or more and less than 1.00, a copper alloy material can be obtained, which has a sufficiently high volume resistivity, a small absolute value of the thermal electromotive force against copper, and a small absolute value of the temperature coefficient of resistance, and further a copper alloy material with excellent punching processability can be obtained. On the other hand, for the copper alloy materials of Comparative Examples 1 and 2, although they have a specific composition, they cannot obtain sufficient stamping processability because the cumulative degree of <111>-oriented grains in the direction parallel to the thickness direction is less than 0.10.

[0150] In addition, the copper alloy materials of Comparative Examples 3, 5, and 6 that do not contain a specific composition are inferior in any one of stamping processability, volume resistivity ρ, thermoelectromotive force (EMF) with respect to copper, and temperature coefficient of resistance (TCR) in terms of the characteristics of a resistance material. In addition, the copper alloy material of Comparative Example 4 that does not contain a specific composition and has a cumulative degree of <111> oriented grains of less than 0.10 in the direction parallel to the thickness direction cannot obtain sufficient stamping processability and has poor volume resistivity in terms of the characteristics of a resistance material.

[0151] (2) Experiment 2: Evaluation of reliability

[0152] For the copper alloy materials of Examples 1 to 17 prepared in Experiment 1, the reliability was further evaluated.

[0153] [1] Evaluation of reliability

[0154] In order to investigate the reliability when the copper alloy material is used as a resistance material or the like for a long time, especially the stability of electrical characteristics such as heat, for the test material after measuring the volume resistivity in the measurement of [3] volume resistivity in Experiment 1 above, heating was carried out at 400 °C for 2 hours to perform an accelerated test on the stability of electrical characteristics with respect to heat. After the accelerated test by heating, the volume resistivity of the test material was measured using the same method as the measurement of [3] volume resistivity in Experiment 1 above, and then the difference in volume resistivity obtained by subtracting the volume resistivity after heating from the volume resistivity before heating (the difference in volume resistivity before and after heating) was obtained.

[0155] [Table 4]

[0156]

[0157] As shown in Tables 1 and 4, in Examples 1 to 17 where the Fe content is 0.5 mass% or less, the difference in volume resistivity before and after heating is all 2.6 μΩ·cm or less, and it was confirmed that the reliability is good when used as a resistance material for a long time. Further, in Examples 1 to 3, 6, 9, 10, 13 to 15, and 17 that do not contain Fe, the difference in volume resistivity before and after heating is all less than 0.1 μΩ·cm, and it was confirmed that the reliability is particularly excellent when used as a resistance material for a long time.

[0158] Reference numerals

[0159] 10: Copper alloy material

[0160] 10a: Top surface of the copper alloy material

[0161] 10b: Bottom surface of the copper alloy material

[0162] 2: Cut surface

[0163] 3: Collapsed corner

[0164] 4: Shearing surface

[0165] 5: Fracture surface

[0166] 6: Front end of burr

[0167] 7: Boundary line

[0168] 11: Test material

[0169] 21: Standard copper wire

[0170] 31, 32: Copper wire

[0171] 41: Constant temperature bath

[0172] 42: Ice point device

[0173] 43: Voltage detector

[0174] P1: Temperature measurement contact point

[0175] P 21 , P 22 : Reference contact point

[0176] t all : Thickness of copper alloy material

[0177] t1: Length of collapsed corner

[0178] t2: Length of shearing surface

[0179] t3: Length of fracture surface

[0180] x: Width direction

[0181] y: Extension direction

[0182] z: Thickness direction

Claims

1. A copper alloy material having the following composition: containing Mn of 20.0 mass% or more and 35.0 mass% or less and Ni of 6.5 mass% or more and 17.0 mass% or less, the balance being composed of Cu and unavoidable impurities, In a cross-section including the rolling direction and the thickness direction of the copper alloy material, when performing crystal orientation analysis by the EBSD method, the cumulative degree of grains having a <111> orientation in the direction parallel to the thickness direction is 0.10 or more and less than 1.

00.

2. The copper alloy material according to claim 1, wherein, The cumulative degree of grains having a <111> orientation in the direction parallel to the thickness direction is 0.20 or more.

3. The copper alloy material according to claim 1, wherein, The composition further contains at least one of Fe of 0.01 mass% or more and 0.50 mass% or less and Co of 0.01 mass% or more and 2.00 mass% or less.

4. The copper alloy material according to claim 1, wherein, The composition further contains at least one selected from the group consisting of the following components: Sn of 0.01 mass% or more and 3.00 mass% or less, Zn of 0.01 mass% or more and 5.00 mass% or less, Cr of 0.01 mass% or more and 0.50 mass% or less, Ag of 0.01 mass% or more and 0.50 mass% or less, Al of 0.01 mass% or more and 1.00 mass% or less, Mg of 0.01 mass% or more and 0.50 mass% or less, Si of 0.01 mass% or more and 0.50 mass% or less and P of 0.01 mass% or more and 0.50 mass% or less.

5. A resistive material for a resistor, which is composed of the copper alloy material according to any one of claims 1 to 4.

6. A resistor, which is a shunt resistor or a chip resistor, and the resistor has the resistive material for a resistor according to claim 5.

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