WO2024135787A1 - Copper alloy material, resistive material including same for resistor, and resistor - Google Patents

Abstract

Provided are: a copper alloy material which chips little when punched with a press and which has a sufficiently high volume resistivity, a temperature coefficient of resistance (TCR) that is negative and is small in absolute value, and a small absolute value of copper electromotive force (EMF); a resistive material including the copper alloy material, for a resistor; and the resistor.　The copper alloy material has an alloy composition containing 20.0-35.0 mass% Mn and 6.5-17.0 mass% Ni, with the remainder comprising Cu and unavoidable impurities. The copper alloy material, when a longitudinal section thereof including a drawing direction and a thickness direction is analyzed for crystallographic orientation by the SEM-EBSD method, gives a crystallographic-orientation distribution function (ODF) which, when expressed by Euler angles (φ1, Φ, φ2), has a maximum orientation density of 6.0 or less in an area where φ1 is 0-90°, φ is 0-90°, and φ2 is 15°, 20°, and 25°.

Description

Copper alloy material, and resistor material and resistor using the same

The present invention relates to a copper alloy material and a resistor material and resistor using the same.

It is desirable that the metallic material of the resistive material used in a resistor has a stable resistance even when the environmental temperature changes. For this reason, the resistive material is required to have a small absolute value of the temperature coefficient of resistance (TCR), which is an index showing the characteristic of a stable resistance value against temperature changes. The temperature coefficient of resistance is expressed in parts per million (ppm) per degree Celsius, and is expressed by the formula TCR (×10 ⁻⁶ /° C.) = {(R-R ₀ )/R ₀ }×{1/(T-T ₀ )}×10 ^6. Here, in the formula, T is the test temperature (° C.), T ₀ is the reference temperature (° C.), R is the resistance value (Ω) at the test temperature T, and R ₀ is the resistance value (Ω) at the reference temperature T _0. In particular, Cu-Mn-Ni alloys and Cu-Mn-Sn alloys have a very small TCR and are therefore widely used as alloy materials constituting resistive materials.

However, when these Cu-Mn-Ni alloys or Cu-Mn-Sn alloys are used as resistive materials in resistors designed to have a predetermined resistance value by forming a circuit (pattern) using the resistive material, the volume resistivity is small, less than 50×10 ^-8 (Ω·m), so it is necessary to reduce the cross-sectional area of the resistive material to increase the resistance value of the resistor. In such resistors, when a large current flows temporarily in the circuit or when a relatively large current continues to flow all the time, Joule heat generated in the resistive material with a small cross-sectional area becomes high and heat is generated, resulting in the resistive material being easily broken (melted) by the heat.

For this reason, there is a demand for resistive materials with a higher volume resistivity to prevent the cross-sectional area of the resistive material from becoming smaller.

For example, Patent Document 1 describes a copper alloy containing Mn in the range of 23 mass % to 28 mass % and Ni in the range of 9 mass % to 13 mass %, and by configuring the mass fractions of Mn and Ni so that the thermoelectromotive force against copper is less than ±1 μV/°C at 20°C, it is possible to obtain a copper alloy having a high electrical resistance (volume resistivity ρ) of 50× ^10-8 [Ω·m] or more, a small thermoelectromotive force against copper (copper thermoelectromotive force, EMF), a low temperature coefficient of electrical resistance, and high stability over time of the intrinsic electrical resistance (time invariance).

Patent Document 2 also claims that by including 33% to 38% by mass of Mn and 8% to 15% by mass of Ni in an alloy for resistors containing copper, manganese, and nickel, it is possible to obtain a copper-manganese-nickel alloy that has properties (particularly resistivity) similar to those of nickel-chromium alloys and has superior workability compared to nickel-chromium alloys.

Special table 2016-528376 publication JP 2021-161512 A

　In recent years, as electrical and electronic components have become smaller and more highly integrated, resistors and the resistive materials used in them have also become smaller. The resistive materials used in resistors are generally formed by cutting processes such as press punching, so in order to reduce the variation in resistance value, the copper alloy material must have excellent press punching workability. In particular, when press punching is performed on copper alloy material, it is required that the cut surface, which is the punching surface, is formed in a fixed position in order to reduce the variation in resistance value.

However, copper alloys that contain high concentrations of Mn and Ni to increase the volume resistivity have high mechanical strength due to solid solution strengthening, and are characterized by strong bonding forces between the atoms that make up the copper alloy. On the other hand, such copper alloys have the characteristic that when a plate is produced and then punched using a press, the strong bonding forces between the atoms make it easy for the cut surfaces, especially the fractured surfaces, to be gouged out. When the fractured surfaces are gouged out, the cross-sectional area of the resistance material obtained by press punching is partially reduced in the vicinity of the cut surfaces, which could impair the accuracy of the electrical resistance of the resistance material.

Furthermore, in recent years, resistors such as shunt resistors and chip resistors in the electrical systems of electric vehicles are required to have a high volume resistivity ρ as well as high precision that can withstand higher temperature environments, and the copper alloys used in such resistors are also required to have high precision that can withstand higher temperature environments. More specifically, there is a demand for copper alloy materials that have a high volume resistivity ρ, and when considering the wide temperature range of use from room temperature to high temperatures, have a negative temperature coefficient of resistance (TCR) with a small absolute value, and a small absolute value of thermal electromotive force (EMF) against copper.

The object of the present invention is therefore to provide a copper alloy material that has small gouges on the punched surface during press punching, has a sufficiently high volume resistivity, has a negative temperature coefficient of resistance (TCR) with a small absolute value, and has a small absolute value of thermal electromotive force (EMF) against copper, as well as a resistor material and a resistor using the same.

The inventors have discovered that by using a copper alloy material having an alloy 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, with the remainder being Cu and unavoidable impurities, and in which the maximum value of the orientation density at φ1=0-90°, Φ=0-90°, and φ2=15°, 20°, and 25° is 6.0 or less when the crystal orientation distribution function (ODF) is expressed as Euler angles (φ1, Φ, φ2), it is possible to obtain a copper alloy material that reduces gouges that occur during press punching, has a sufficiently high volume resistivity ρ as a resistance material, and takes into account the use environment in a wide temperature range from room temperature (e.g., 20°C) to high temperature (e.g., 150°C), has a negative temperature coefficient of resistance (TCR) with a small absolute value, and also has a small absolute value of thermal electromotive force (EMF) against copper, thereby completing the present invention.

In order to achieve the above object, the gist of the present invention is as follows.
(1) A copper alloy material having an alloy composition containing 20.0 mass% or more and 35.0 mass% or less of Mn, and 6.5 mass% or more and 17.0 mass% or less of Ni, with the balance being Cu and unavoidable impurities, wherein, in a longitudinal section including an elongation direction and a thickness direction of the copper alloy material, a crystal orientation distribution function (ODF) obtained by a crystal orientation analysis by a SEM-EBSD method is expressed as Euler angles (φ1, Φ, φ2), the maximum value of the orientation density at φ1=0 to 90°, Φ=0 to 90°, and φ2 of 15°, 20°, and 25° is 6.0 or less.
(2) In the longitudinal section, an average crystal grain size of crystal grains obtained from crystal orientation analysis data by a SEM-EBSD method is 20 μm or less, and a standard deviation of the average crystal grain size is 10 μm or less. The copper alloy material according to (1) above.
(3) The copper alloy material according to (1) or (2) above, wherein the alloy composition further contains one or both of Fe: 0.01 mass% or more and 0.50 mass% or less and Co: 0.01 mass% or more and 2.00 mass% or less.
(4) The copper alloy material according to any one of (1) to (3), further comprising at least one selected from the group consisting of Sn: 0.01% by mass or more and 5.00% by mass or less, Zn: 0.01% by mass or more and 5.00% by mass or less, Cr: 0.01% by mass or more and 0.50% by mass or less, Ag: 0.01% by mass or more and 0.50% by mass or less, Al: 0.01% by mass or more and 1.00% by mass or less, Mg: 0.01% by mass or more and 0.50% by mass or less, Si: 0.01% by mass or more and 0.50% by mass or less, and P: 0.01% by mass or more and 0.50% by mass or less.
(5) A resistive material for a resistor, comprising the copper alloy material according to any one of (1) to (4) above.
(6) A resistor, which is a shunt resistor or a chip resistor, comprising the resistive material for resistors according to (5) above.

The present invention provides a copper alloy material that has small gouges on the punched surface during press punching, has a sufficiently high volume resistivity, has a negative temperature coefficient of resistance (TCR) with a small absolute value, and has a small absolute value of thermal electromotive force (EMF) against copper, as well as a resistor material and resistors using the same.

FIG. 1 is a schematic diagram of the punched copper alloy material of the present invention when viewed from a direction parallel to the cut surface in order to understand the contour shape (right edge portion) of the cut surface when the punched copper alloy material is subjected to press punching. FIG. 2 is a schematic diagram for explaining a method for determining the thermoelectromotive force (EMF) against copper for each of the test materials of the invention examples and the comparative examples. FIG. 3 is a graph showing the crystal orientation distribution function (ODF) of the copper alloy material of Example 14 of the present invention, expressed as Euler angles (φ1, Φ, φ2), with φ1 on the horizontal axis and Φ on the vertical axis, showing the orientation density in the ranges of φ1=0 to 90° and Φ=0 to 90°, where FIG. 3(a) is a graph when φ2=15°, FIG. 3(b) is a graph when φ2=20°, and FIG. 3(c) is a graph when φ2=25°. FIG. 4 shows scanning electron microscope (SEM) photographs of the punched copper alloy materials observed from a direction parallel to the cut surface in order to understand the contour shape (right edge portion) of the cut surface of the punched copper alloy materials of the present invention and comparative examples, in which FIG. 4( a) shows the copper alloy material of Present Invention Example 5 and FIG. 4( b) shows the copper alloy material of Comparative Example 1.

Below, a preferred embodiment of the copper alloy material of the present invention will be described in detail. Note that in the component composition of the alloy of the present invention, "mass %" may be simply indicated as "%."

The copper alloy material according to the present invention has an alloy composition containing Mn: 20.0% by mass to 35.0% by mass, Ni: 6.5% by mass to 17.0% by mass, with the remainder being Cu and unavoidable impurities, and when the crystal orientation distribution function (ODF) obtained from crystal orientation analysis by SEM-EBSD method in a longitudinal section including the elongation direction and thickness direction of the copper alloy material is expressed in terms of Euler angles (φ1, Φ, φ2), the maximum orientation density at φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 of 15°, 20°, and 25° is 6.0 or less.

In this way, in the copper alloy material according to the present invention, for a copper alloy material 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, when the crystal orientation distribution function (ODF) is expressed as Euler angles (φ1, Φ, φ2), the maximum value of the orientation density at φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 = 15°, 20°, and 25° is set to 6.0 or less, so that grains having crystal orientations with similar mechanical properties are not unnecessarily densely packed, and gouging of the fracture surface that occurs during press punching can be suppressed.

In addition, the copper alloy material according to the present invention contains Mn in the range of 20.0 mass% to 35.0 mass% and Ni in the range of 5.0 mass% to 17.0 mass%, which increases the volume resistivity ρ, reduces the absolute value of the temperature coefficient of resistance (TCR) (hereinafter sometimes simply referred to as "temperature coefficient of resistance") in the temperature range of 20°C to 150°C, and reduces the absolute value of the thermoelectromotive force against copper. Also, in the copper alloy material according to the present invention, the absolute value of the thermoelectromotive force against copper (EMF) (hereinafter sometimes simply referred to as "thermoelectromotive force against copper") generated between temperature environments of 20°C and 80°C is reduced, so that resistors can be manufactured with high precision even in high-temperature environments.

In this regard, in the copper alloy described in the above-mentioned Patent Document 1, in order to reduce the absolute value of the copper thermoelectromotive force (EMF), it is necessary to increase the Ni content, and in that case, the absolute value of the temperature coefficient of resistance (TCR) tends to increase. In addition, in the copper alloy described in the above-mentioned Patent Document 1, the temperature coefficient of resistance (TCR) becomes a large negative number in the temperature range from 20°C to 150°C, including the higher temperature range, as shown in, for example, FIG. 3 of Patent Document 1, with respect to the temperature dependence of the electrical resistance, so that the resistance value tends to be prone to errors in the high temperature range. However, in the copper alloy material according to the present invention, it is possible to suppress the absolute value of the temperature coefficient of resistance (TCR) from increasing in the temperature range from 20°C to 150°C, so that it has a sufficiently high volume resistivity as a resistance material, and is also excellent in that it has a small absolute value of the temperature coefficient of resistance and a small absolute value of the thermoelectromotive force against copper, taking into account the use environment in a wide temperature range from room temperature (e.g., 20°C) to high temperature (e.g., 150°C).

As a result, by using the copper alloy material according to the present invention, it is possible to provide a copper alloy material that has small gouges on the punched surface during press punching, has a sufficiently high volume resistivity ρ, has a negative temperature coefficient of resistance (TCR) with a small absolute value, and has a small absolute value of thermal electromotive force (EMF) against copper, as well as a resistor material for resistors and resistors using the same.

[1] Composition of copper alloy material <Essential additive components>
The alloy composition of the copper alloy material of the present invention contains, as essential additive components, Mn: 20.0 mass % or more and 35.0 mass % or less, and Ni: 6.5 mass % or more and 17.0 mass % or less.

(Mn: 20.0 mass% or more and 35.0 mass% or less)
Mn (manganese) is an element that increases the volume resistivity ρ. In order to exert this effect and obtain a homogeneous copper alloy material, the Mn content is preferably 20.0 mass% or more, and 22.0 mass% or more. It is more preferable that the Mn content is 22.0 mass% or more, and further preferably 24.0 mass% or more. Here, by increasing the Mn content to 22.0 mass% or more or 24.0 mass% or more, On the other hand, when the Mn content exceeds 35.0 mass%, the melting point of the copper alloy material is lowered, which may cause problems in the production and In particular, it becomes difficult to control hot working, and therefore it becomes difficult to obtain uniform properties. Also, when the Mn content exceeds 35.0 mass %, the absolute value of the thermoelectromotive force (EMF) against copper becomes For this reason, the Mn content is set to the range of 20.0 mass % or more and 35.0 mass % or less.

(Ni: 6.5% by mass or more and 17.0% by mass or less)
Ni (nickel) is an element that adjusts the thermal electromotive force (EMF) relative to copper in a positive direction. To exert this effect, it is preferable that Ni is contained in an amount of 6.5 mass % or more. If the Ni content exceeds 17.0 mass %, it becomes difficult to obtain a uniform structure, and there is a risk that the volume resistivity ρ and the thermoelectromotive force (EMF) against copper may change. If the Ni content exceeds 17.0 mass %, the thermal electromotive force (EMF) against copper tends to be a large positive number, and the absolute value of the temperature coefficient of resistance (TCR) tends to be large. From the viewpoint of obtaining a copper alloy material having desired characteristics and from the viewpoint of obtaining a copper alloy material that is easy to manufacture, the range of 6.5 mass % or more and 17.0 mass % or less is set to 6.5 mass % or more and 12.0 mass % or less. % or less, and more preferably in the range of 6.5 mass % or more and 9.0 mass % or less.

<First optional added component>
The alloy composition of the copper alloy material of the present invention may further contain, as optional additive components, one or both of Fe: 0.01 mass% or more and 0.50 mass% or less and Co: 0.01 mass% or more and 2.00 mass% or less. In particular, by containing one or both of Fe and Co, the absolute value of the temperature coefficient of resistance (TCR) can be made smaller.

(Fe: 0.01% by mass or more and 0.50% by mass or less)
Fe (iron) is an element that adjusts the thermoelectromotive force (EMF) with respect to copper in a positive direction. To exert this effect, it is preferable that Fe is contained in an amount of 0.01 mass % or more. However, when the Fe content exceeds 0.50 mass %, it becomes difficult to obtain a uniform structure, and the electrical performance is likely to vary. In particular, it is necessary to further improve the stability of the electrical properties against heat, etc. From the viewpoint of improving the reliability when used for a long period of time as a resistance material, the Fe content is more preferably 0.20 mass % or less. From the viewpoint of further increasing the content of Co, it is preferable to contain Co rather than Fe. In other words, it is preferable not to contain Fe, and to contain Co, which will be described later, if necessary. Therefore, the Fe content is 0. The content of the Cr-based alloy is preferably in the range of 0.01% by mass or more and 0.50% by mass or less, and more preferably in the range of 0.01% by mass or more and 0.20% by mass or less.

(Co: 0.01% by mass or more and 2.00% by mass or less)
Co (cobalt) is an element that adjusts the thermoelectromotive force (EMF) with respect to copper in a positive direction. To exert this effect, it is preferable that Co is contained in an amount of 0.01 mass % or more. If the Co content exceeds 2.00 mass%, it becomes difficult to obtain a uniform structure, and the electrical performance tends to vary. Therefore, the Co content is set to 0.01 mass% or less. It is preferable to set the content in the range of 1.00 mass % or more and 2.00 mass % or less.

<Second Optional Added Component>
The alloy composition of the copper alloy material of the present invention may further contain, as an optional additive component, at least one selected from the group consisting of Sn: 0.01% by mass or more and 5.00% by mass or less, Zn: 0.01% by mass or more and 5.00% by mass or less, Cr: 0.01% by mass or more and 0.50% by mass or less, Ag: 0.01% by mass or more and 0.50% by mass or less, Al: 0.01% by mass or more and 1.00% by mass or less, Mg: 0.01% by mass or more and 0.50% by mass or less, Si: 0.01% by mass or more and 0.50% by mass or less, and P: 0.01% by mass or more and 0.50% by mass or less.

(Sn: 0.01% by mass or more and 5.00% by mass or less)
Sn (tin) is a component that can be used to adjust the volume resistivity ρ. To achieve this effect, it is preferable to contain 0.01 mass % or more of Sn. On the other hand, the Sn content is By making the content of C 5.00 mass % or less, it is possible to make it difficult for the copper alloy material to become brittle, which can lead to a decrease in manufacturability.

(Zn: 0.01% by mass or more and 5.00% by mass or less)
Zn (zinc) is a component that can be used to adjust the volume resistivity ρ. To achieve this effect, it is preferable to contain Zn in an amount of 0.01 mass % or more. On the other hand, the Zn content is However, since there is a risk of adversely affecting the stability of the electrical performance of the resistor, such as the volume resistivity ρ and the thermal electromotive force (EMF) against copper, it is preferable to keep the content at 5.00 mass % or less.

(Cr: 0.01% by mass or more and 0.50% by mass or less)
Cr (chromium) is a component that can be used to adjust the volume resistivity ρ. To achieve this effect, it is preferable to contain 0.01 mass % or more of Cr. On the other hand, the Cr content is However, since there is a risk of adversely affecting the stability of the electrical performance of the resistor, such as the volume resistivity ρ and the thermal electromotive force (EMF) against copper, it is preferable to keep the content at 0.50 mass % or less.

(Ag: 0.01% by mass or more and 0.50% by mass or less)
Silver (Ag) is a component that can be used to adjust the volume resistivity ρ. To achieve this effect, it is preferable to contain 0.01 mass % or more of Ag. On the other hand, the Ag content is However, since there is a risk of adversely affecting the stability of the electrical performance of the resistor, such as the volume resistivity ρ and the thermal electromotive force (EMF) against copper, it is preferable to keep the content at 0.50 mass % or less.

(Al: 0.01% by mass or more and 1.00% by mass or less)
Al (aluminum) is a component that can be used to adjust the volume resistivity ρ. To achieve this effect, it is preferable to contain 0.01 mass % or more of Al. On the other hand, the Al content is However, since there is a risk of embrittlement of the copper alloy material, it is preferable to set the content to 1.00 mass % or less.

(Mg: 0.01% by mass or more and 0.50% by mass or less)
Mg (magnesium) is a component that can be used to adjust the volume resistivity ρ. To achieve this effect, it is preferable to contain 0.01 mass % or more of Mg. On the other hand, the Mg content is However, since there is a risk of embrittlement of the copper alloy material, the content is preferably 0.50 mass % or less.

(Si: 0.01% by mass or more and 0.50% by mass or less)
Si (silicon) is a component that can be used to adjust the volume resistivity ρ. To achieve this effect, it is preferable to contain 0.01 mass % or more of Si. On the other hand, the Si content is However, since there is a risk of embrittlement of the copper alloy material, the content is preferably 0.50 mass % or less.

(P: 0.01% by mass or more and 0.50% by mass or less)
P (phosphorus) is a component that can be used to adjust the volume resistivity ρ. To achieve this effect, it is preferable to contain P in an amount of 0.01 mass % or more. On the other hand, the P content is However, since there is a risk of embrittlement of the copper alloy material, the content is preferably 0.50 mass % or less.

(Total amount of second optional added components: 0.01% by mass or more and 5.00% by mass or less)
In order to obtain the effects of the second optional additive components, the second optional additive components composed of at least one component selected from the group consisting of Sn, Zn, Cr, Ag, Al, Mg, Si, and P are preferably contained in a total amount of 0.01 mass% or more. On the other hand, if these second optional additive components are contained in a large amount, the electrical characteristics become unstable and it becomes difficult to manufacture the copper alloy material, so that the total amount of these second optional additive components is preferably 5.00 mass% or less.

<Balance: Cu and inevitable impurities>
Other than the above-mentioned essential components and optional additive components, the remainder is composed of Cu (copper) and inevitable impurities. The "unavoidable impurities" referred to here are generally those present in raw materials in copper-based products or those inevitably mixed in during the manufacturing process, and are essentially unnecessary impurities that are allowed because they are in small amounts and do not affect the properties of copper-based products. Examples of components that can be cited as inevitable impurities include nonmetallic elements such as sulfur (S) and metallic elements such as antimony (Sb). The upper limit of the content of these components can be 0.05 mass% for each of the above components, and 0.10 mass% for the total amount of the above components.

[2] Maximum orientation density at φ1=0-90°, Φ=0-90°, and φ2=15°, 20°, and 25° when the crystal orientation distribution function (ODF) is expressed as Euler angles In the copper alloy material of the present invention, when the crystal orientation distribution function (ODF) obtained by crystal orientation analysis by SEM-EBSD method is expressed as Euler angles (φ1, Φ, φ2) in a longitudinal section including the extension direction and thickness direction of the copper alloy material, the maximum value of the orientation density at φ1=0-90°, Φ=0-90°, and φ2=15°, 20°, and 25° is 6.0 or less. In a copper alloy material containing a large amount of Mn and Ni as in the present invention, crystal grains tend to be easily oriented in a specific orientation such as S orientation or Copper orientation. Here, when the orientation in a specific direction becomes dominant, crystal grains having similar mechanical characteristics are densely packed, and in such a case, when press punching is performed, the gouging of the fracture surface at the fracture surface is likely to become large. Therefore, in order to suppress the gouging of the fracture surface when press punching is performed, it is necessary to suppress the orientation of the crystal grains in a specific direction, and for this purpose, when the crystal orientation distribution function (ODF) is expressed by Euler angles (φ1, Φ, φ2), the maximum values of the orientation density at φ1 = 0 to 90 °, Φ = 0 to 90 °, and φ2 = 15, 20, and 25 ° are set to 6.0 or less, respectively. By setting the maximum value of the orientation density in this range to 6.0 or less, crystal grains oriented in a specific direction such as S orientation or Copper orientation will not accumulate more than necessary, so that grains having crystal orientations with similar mechanical properties will not be densely packed. Therefore, the gouging of the fracture surface that occurs when press punching is performed can be suppressed, and a flatter cut surface can be obtained. As a result, the cross-sectional area of the resistive material obtained by the press punching process is less likely to be damaged by gouging of the fracture surface, even in the vicinity of the cut surface, so that a copper alloy material suitable for producing a resistor with higher precision can be obtained.

Therefore, from the viewpoint of obtaining a copper alloy material suitable for obtaining resistors with higher precision by suppressing the gouging of the fracture surface that occurs during press punching, when the crystal orientation distribution function (ODF) is expressed as Euler angles (φ1, Φ, φ2), the maximum orientation density (orientation) at φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 = 15, 20, and 25° is 6.0 or less, and preferably 5.7 or less.

When the crystal orientation distribution function (ODF) is expressed in terms of Euler angles (φ1, Φ, φ2), the maximum orientation density at φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 = 15, 20, and 25° is the value obtained from the crystal orientation analysis data using the SEM-EBSD method.

Here, the crystal orientation analysis data of the SEM-EBSD method can be obtained by preparing a cross-sectional sample by mirror-polishing a cross-section parallel to the elongation direction of the copper alloy material, observing the cross-sectional sample using a field emission scanning electron microscope (FE-SEM), and performing EBSD measurement (measurement by electron backscatter diffraction method). The area to be measured in the EBSD measurement can be ^0.02 mm2 or more, and the measurement step can be 0.5 μm.

From the EBSD measurement results, the maximum orientation density can be obtained using an ODF map obtained using the data analysis software "OIM ANALYSIS". More specifically, the strength is calculated using the harmonic series expansion, with the series rank set to 16 and the Gaussian half-width set to 5° when fitting to a Gaussian distribution, and texture analysis is performed on the calculation results obtained by selecting Enforce Orthotropic Sample Symmetry to create an ODF map showing the intensity distribution of the crystal orientation when expressed in Euler angles (φ1, Φ, φ2). Using this, the maximum orientation density can be obtained for φ1 = 0-90°, Φ = 0-90°, and φ2 = 15°, 20°, and 25°.

When the crystal orientation distribution function (ODF) is expressed in terms of Euler angles (φ1, Φ, φ2), the maximum orientation density at φ1 = 0-90°, Φ = 0-90°, and φ2 = 15, 20, and 25° is expressed as a relative value when the density of crystal grains oriented at the corresponding Euler angles (φ1, Φ, φ2) when the crystal grains are completely randomly oriented is set to 1.

[3] Average grain size and standard deviation of crystal grains of copper alloy material In the copper alloy material of the present invention, it is preferable that the average grain size of the crystal grains is in the range of 20 μm or less and the standard deviation of the average grain size is 10 μm or less. This makes it possible to reduce the gouging of the fracture surface, which is the punched surface, when the copper alloy material is subjected to press punching.

The average grain size and its standard deviation of the crystal grains of the copper alloy material can be obtained from the crystal orientation analysis data of the SEM-EBSD method described above for a longitudinal section including the elongation direction and thickness direction of the copper alloy material, and more specifically, can be determined from a Grain Size (diameter) graph obtained using the data analysis software "OIM ANALYSIS." In this case, the average diameter and standard deviation determined from the Area Fraction can be regarded as the average grain size and its standard deviation of the crystal grains.

[4] Shape of copper alloy material The shape of the copper alloy material of the present invention is not particularly limited, but is preferably a plate material from the viewpoint of facilitating the hot or cold processing step described below and cutting processing such as press punching. Here, in the copper alloy material formed by rolling, such as a plate material, the rolling direction can be the stretching direction. On the other hand, the copper alloy material of the present invention may be a wire material, a rectangular wire material, a ribbon material, a strip material, or a bar material, and by forming these shapes with the copper alloy material of the present invention, it is possible to facilitate cutting processing of the terminal. Here, in the copper alloy material of these shapes formed by wire drawing, drawing, or extrusion, any of the wire drawing direction, drawing direction, and extrusion direction can be the stretching direction.

[5] An example of a manufacturing method for a copper alloy material The above-mentioned copper alloy material can be realized by controlling a combination of an alloy composition and a manufacturing process, and the manufacturing process is not particularly limited. Among them, the following method can be cited as an example of a manufacturing process that can obtain the above-mentioned copper alloy material.

As an example of a method for producing the copper alloy material of the present invention, a copper alloy material having substantially the same alloy composition as the copper alloy material described above is subjected to at least a casting step [step 1], a homogenization heat treatment step [step 2], a hot working step [step 3], and a first heat treatment step [step 4] in sequence, and then a cold working step and a heat treatment step are repeated two or more times, more preferably four or more times. Of these, in the homogenization heat treatment step [step 2], the heating temperature is in the range of 750°C or more and 900°C or less, and the temperature holding time at the heating temperature is in the range of 10 minutes or more and 10 hours or less. In addition, the cold working steps repeated after the first heat treatment step [step 4] each have a total working rate in the range of 40% or more and 65% or less. In addition, the heat treatment steps repeated after the first heat treatment step [step 4] are performed at a heating temperature in the range of 650°C to 850°C, with heating from room temperature to the heating temperature within 15 seconds, and the temperature holding time at the heating temperature is in the range of 1 second to 40 seconds.

(i) Casting process [Process 1]
In the casting step [step 1], a copper alloy material having the above-mentioned alloy composition is melted in an inert gas atmosphere or in vacuum using a high-frequency melting furnace, and the melt is cast into a desired shape (for example, a thick Ingots with dimensions of 30-300 mm in length, 500 mm in width, and 3000 mm in length are produced. Note that the alloy composition of the copper alloy material varies depending on the additives, as they may adhere to the melting furnace or volatilize during each manufacturing process. Although the alloy composition of the copper alloy material produced by the above-mentioned method may not be completely identical to that of the copper alloy material produced by the above-mentioned method, the alloy composition of the copper alloy material produced by the above-mentioned method is substantially the same as that of the copper alloy material.

(ii) Homogenization heat treatment step [Step 2]
The homogenization heat treatment step [step 2] is a step of performing a homogenizing heat treatment on the ingot after the casting step [step 1]. Here, the conditions of the heat treatment in the homogenization heat treatment step [step 2] are preferably a heating temperature in the range of 750°C to 900°C and a holding time in the range of 10 minutes to 10 hours from the viewpoint of suppressing the coarsening of crystal grains.

(iii) Hot working step [Step 3]
The hot working step [step 3] is a step in which the ingot that has been subjected to the homogenization heat treatment is subjected to hot rolling or drawing such as wire drawing until it has a predetermined thickness, thereby producing a hot-rolled material. The conditions of the hot working step [step 3] are that the working temperature is preferably in the range of 700°C to 850°C, and may be the same as the heating temperature in the homogenization heat treatment step [step 2]. In addition, the working rate in the hot working step [step 3] is preferably 50% or more.

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

The hot-rolled material is preferably cooled after the hot working step [Step 3]. Here, it is preferable to use water cooling as a means for cooling the hot-rolled material, from the viewpoint of obtaining a fine and uniform crystal structure with an average crystal grain size of 50 μm or less. On the other hand, it is possible to cause grain growth by slowing down the cooling rate after the hot working step, but this is not appropriate because it is difficult to maintain a uniform temperature throughout the hot-rolled material, and as a result, it is difficult to obtain a uniform structure.

(iv) First heat treatment step [Step 4]
Next, the water-cooled hot-rolled material is subjected to a first heat treatment step [step 4] to adjust the average grain size. Here, the step of adjusting the average grain size to more than 100 μm is performed by performing heat treatment at a temperature of 650° C. to 850° C. for 2 hours to 5 hours. By using a heat treatment furnace to obtain a uniform structure with an average grain size of more than 100 μm, the development of the texture formed by subsequent processing is inhibited, and the maximum value of the orientation density can be reduced.

Here, facing may be performed on the hot-rolled material after the first heat treatment step [step 4] to remove the surface. By performing facing, it is possible to remove the oxide film and defects on the surface that occurred in the hot working step [step 3]. The conditions for facing can be any conditions that are normally used, and are not particularly limited. The amount of material removed from the surface of the hot-rolled material by facing can be appropriately adjusted based on the conditions of the hot working step [step 3], and can be, for example, about 0.5 mm to 4 mm from the surface of the hot-rolled material.

(v) Repeated cold working and heat treatment steps The hot-rolled material after the first heat treatment step [step 4] is subjected to a cold working step of performing elongation such as cold rolling and wire drawing until the thickness and size of the product is reached, and a heat treatment step of performing heat treatment is repeated two or more times. More specifically, the hot-rolled material after the first heat treatment step [step 4] after hot working is subjected to at least a first cold working step, a first heat treatment step, a second cold working step, and a second heat treatment step, and the cold working steps and heat treatment steps at this time can be the first cold working step [step 5], the second heat treatment step [step 6], the second cold working step [step 7], and the third heat treatment step [step 8], in that order. Furthermore, the cold-rolled material after the third heat treatment step [step 8] can be subjected to a third cold working step and a heat treatment step, and the cold working step and the heat treatment step at this time can be respectively designated as the third cold working step [step 9] and the fourth heat treatment step [step 10]. Furthermore, the cold-rolled material after the fourth heat treatment step [step 10] can be subjected to a fourth cold working step and a heat treatment step, and the cold working step and the heat treatment step at this time can be respectively designated as the fourth cold working step [step 11] and the fifth heat treatment step [step 12]. In this way, by repeating the cold working step and the heat treatment step two or more times on the hot-rolled material after the first heat treatment step [step 4], the maximum value of the orientation density when the crystal orientation distribution function (ODF) is expressed as Euler angles and at φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 is 15°, 20°, and 25° becomes small, so that the gouges on the punched surface that occur during press punching can be reduced.

In this case, the total working ratios in the first cold working step [step 5], the second cold working step [step 7], the third cold working step [step 9] and the fourth cold working step [step 11] are each in the range of 40% to 65%. If the cold working steps after the second cold working step [step 7] are not performed, or if the total working ratio in at least any of the first cold working step [step 5], the second cold working step [step 7], the third cold working step [step 9] and the fourth cold working step [step 11] is less than 40%, recrystallization is unlikely to occur, making it difficult to obtain a uniform structure. In addition, if the total working ratio of at least one of the first cold working step [step 5], the second cold working step [step 7], the third cold working step [step 9], and the fourth cold working step [step 11] exceeds 65%, the maximum values of the orientation density at φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 = 15°, 20°, and 25° when the crystal orientation distribution function (ODF) is expressed as Euler angles become larger than necessary. In particular, it is preferable that the total working ratio in each of the first cold working step [step 5], the second cold working step [step 7], the third cold working step [step 9], and the fourth cold working step [step 11] is 60% or less.

The heat treatment conditions in the second heat treatment step [step 6], the third heat treatment step [step 8], the fourth heat treatment step [step 10] and the fifth heat treatment step [step 12] are preferably such that the heating temperature is in the range of 650°C or more and 850°C or less, heating is performed so as to reach the heating temperature within 15 seconds from room temperature, and the temperature holding time at the heating temperature is in the range of 1 second or more and 40 seconds or less. Here, if the heat treatment time exceeds 1 minute, there is a risk that the standard deviation of the crystal grain size will become large. Therefore, from the viewpoint of adjusting the crystal grain size to an appropriate range and obtaining a uniform crystal structure, it is preferable to shorten the time to reach the heating temperature and also to shorten the temperature holding time at the heating temperature.

[6] Uses of copper alloy material The copper alloy material of the present invention is extremely useful as a resistor material for resistors, for example, shunt resistors or chip resistors. That is, the resistor material is preferably made of the above-mentioned copper alloy material. Moreover, resistors such as shunt resistors or chip resistors preferably have the resistor material made of the above-mentioned copper alloy material.

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and includes all aspects included in the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention.

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

(Inventive Examples 1 to 17 and Comparative Examples 1 to 6)
A copper alloy material having the alloy composition shown in Table 1 was melted, and the molten copper alloy material was cooled and cast in a casting step [Step 1] to obtain an ingot having a thickness of 30 mm. Here, the alloy composition of Comparative Example 1 has the same alloy composition as the copper alloy described in the above-mentioned Patent Document 1 and Example 2 of the above-mentioned Patent Document 2.

The ingot was subjected to a homogenization heat treatment process [Step 2] in which it was heated to 800°C and held for 5 hours, and then to a hot processing process [Step 3] in which it was rolled in the longitudinal direction at a processing temperature of 800°C so that the total processing rate was 67% (thickness before processing: 30 mm, thickness after processing: 10 mm), and then cooled to room temperature by water cooling to obtain a hot-rolled material.

For invention examples 1 to 17 and comparative examples 1 and 3 to 6, the hot-rolled material after water cooling was subjected to a first heat treatment step [step 4] at a heating temperature of 800°C and a holding time of 4 hours to grow crystal grains. On the other hand, for comparative example 2, the first heat treatment step [step 4] was not performed on the hot-rolled material after water cooling.

Next, to remove the oxide film that had formed on the surface, 1 mm was removed from both sides. The thickness of the hot-rolled material after facing was 8 mm.

The hot-rolled material after the hot working process [step 3] was subjected to a first cold working process [step 5] in which it was rolled along the longitudinal direction so that the total working ratio was 62.5% (thickness before working: 8 mm, thickness after working: 3 mm). Next, the cold-rolled material after the first cold working process [step 5] was subjected to a second heat treatment process [step 6] in which it was heat-treated under specified heat treatment conditions.

Furthermore, the cold-rolled material after the second heat treatment step [step 6] was subjected to a second cold working step [step 7] in which it was rolled in the longitudinal direction at the total working ratio shown in Table 2. Next, the cold-rolled material after the second cold working step [step 7] was subjected to a third heat treatment step [step 8] in which it was heat-treated under the heat treatment conditions shown in Table 2.

Furthermore, the cold-rolled material after the third heat treatment step [step 8] was subjected to a third cold working step [step 9] in which it was rolled in the longitudinal direction at the total working ratio shown in Table 2. Next, the cold-rolled material after the third cold working step [step 9] was subjected to a fourth heat treatment step [step 10] in which heat treatment was performed under the heat treatment conditions shown in Table 2.

Furthermore, for present invention examples 1 to 17 and comparative examples 2 to 6, the cold-rolled material after the fourth heat treatment step [step 10] was subjected to a fourth cold working step [step 11], in which the cold-rolled material was rolled in the longitudinal direction at the total working ratio shown in Table 2. Next, the cold-rolled material after the fourth cold working step [step 11] was subjected to a fifth heat treatment step [step 12], in which heat treatment was performed under the heat treatment conditions shown in Table 2. On the other hand, for comparative example 1, the cold-rolled material after the fourth heat treatment step [step 10] was subjected to a fifth heat treatment step [step 12] without performing the fourth cold working step [step 11]. For comparative example 6, the time until the heating temperature was reached in the fifth heat treatment step [step 12] was set to 600 seconds. In this manner, the copper alloy materials (copper alloy sheet materials) of present invention examples 1 to 17 and comparative examples 1 to 6 were produced.

In addition, in Table 1, the columns for components that are not included in the alloy composition of the copper alloy material are marked with a horizontal line "-" to indicate that the corresponding component is not contained, or if it is contained, it is below the detection limit.

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

[1] Measurement of maximum orientation density when crystal orientation distribution function (ODF) is expressed in Euler angles at φ1=0-90°, Φ=0-90°, and φ2=15°, 20°, and 25°. For the copper alloy sheets obtained in the present invention and comparative examples, a cross section parallel to the rolling direction (stretching direction) was mirror-polished to prepare a cross-sectional sample, which was then observed using a field emission scanning electron microscope (FE-SEM) and subjected to EBSD measurement (measurement by electron backscatter diffraction method) to obtain crystal orientation analysis data by the SEM-EBSD method. Here, the area to be measured in the EBSD measurement was 0.02 ^mm2 , and the step during measurement was 0.5 μm. From the EBSD measurement results, the data analysis software "OIM ANALYSIS" was used to perform intensity calculations using the harmonic series expansion, with the series rank set to 16 and the Gaussian half-width set to 5° when fitting to a Gaussian distribution. Symmetry was selected to perform texture analysis, and an ODF map showing the intensity distribution of the crystal orientation when expressed in Euler angles (φ1, Φ, φ2) was plotted. For each of φ2 being 15°, 20°, and 25°, the intensity distribution of the crystal orientation was displayed on a graph showing the orientation density in the ranges of φ1=0 to 90° and Φ=0 to 90°, with φ1 on the horizontal axis and Φ on the vertical axis, thereby determining the maximum values of the orientation density when φ1=0 to 90°, Φ=0 to 90°, and when φ2 was 15°, 20°, and 25°.

[2] Average grain size and standard deviation of copper alloy material The average grain size and standard deviation of copper alloy material were obtained from the graph of grain size (diameter) obtained from the crystal orientation analysis data of the SEM-EBSD method described above using the data analysis software "OIM ANALYSIS". At this time, the average diameter and standard deviation obtained from the area fraction were taken as the average grain size and standard deviation of the grains. The results are shown in Table 1.

[3] Method for evaluating the size of gouges generated in copper alloy material during press punching In order to evaluate the size of gouges generated when the prepared copper alloy material is subjected to press punching, a shear test was performed according to the shear test method for copper and copper alloy thin plate strips specified in the Japan Copper and Brass Association Technical Standard JCBA T310:2019. That is, the mold was adjusted so that the clearance between the upper mold (punch) and the lower mold (die) was in the range of 20 μm to 30 μm, and the ratio of the fracture surface to the cut surface was adjusted to be in the range of 30% to 50%, and the copper alloy material was punched into a square shape having a size of 10 mm along the stretching direction and a size of 10 mm along the plate width direction perpendicular to the stretching direction, to prepare a copper alloy material specimen having a cut surface on the outer periphery.

1 is a schematic diagram of the punched copper alloy material of the present invention when viewed from a direction parallel to the cut surface in order to understand the outline shape (right edge portion) of the cut surface at that time when the copper alloy material is subjected to press punching processing. FIG. 1 shows a schematic outline shape of the cut surface 2 that appears on a plane including a direction X perpendicular to the cut surface 2 and a thickness direction Y. The copper alloy material 1 shown in FIG. 1 shows the cut surface 2 after press punching processing, which is performed by lowering an upper die (punch) while the copper alloy material 1 is fixed on a lower die (die) not shown. Here, the cut surface 2 is formed with a sag 3, a shear surface 4, and a fracture surface 5 in this order from the upper surface 1a side of the press-punched copper alloy material 1. Here, the fracture surface 5 is hollowed out relative to the shear surface 4, and a hollow 6 is often formed on the cut surface 2, which is the punched surface. In addition, a burr 7 is often formed on the lower edge of the cut surface 2 so as to extend outward from the fracture surface 5.

In this embodiment, in order to understand the contour shape (right edge portion) of the cut surface 2 when the copper alloy material 1 of the present invention and the comparative example was subjected to press punching, the punched copper alloy material 1 was observed at a magnification of 300 times from a direction parallel to the cut surface 2 using an optical microscope (Olympus Corporation, model number: GX71) for the test material made of the punched copper alloy material 1. Then, in this scanning electron microscope (SEM) photograph, as shown in FIG. 1, an imaginary line drawn parallel to the plate surface of the copper alloy material (along the direction X in FIG. 1) from the tip of the burr 7 and a boundary line 8 drawn at a position considered to be the boundary between the shear surface 4 and the fracture surface 5 are taken as opposite sides, and the vertices of these opposite sides are connected by a pair of opposite sides drawn in the thickness direction Y to form an imaginary rectangle R having four sides. The proportion of the area of the copper alloy material 1 to the area partitioned by this rectangle R was calculated as a percentage (%).

When the ratio of the area of the overlapping portion 9 of the copper alloy material 1 and the rectangle R to the calculated area of the rectangle R was 42% or more, it was evaluated as excellent in that the gouge 6 formed on the cut surface 2, which is the punched surface, was sufficiently small, and was evaluated as "◎". When the ratio of the area of the overlapping portion 9 of the copper alloy material 1 and the rectangle R to the area of the rectangle R was 30% or more and less than 42%, it was evaluated as good in that the gouge 6 on the punched surface was small, and was evaluated as "○". On the other hand, when the ratio of the area of the overlapping portion 9 of the copper alloy material 1 and the rectangle R to the area of the rectangle R was less than 30%, it was evaluated as poor in that the size of the gouge 6 on the punched surface was not within the appropriate range, and was evaluated as "×". The results are shown in Table 3.

[4] Measurement of Volume Resistivity The prepared copper alloy material was cut into a plate having a thickness of 0.3 mm into a width of 10 mm and a length of 300 mm to prepare a test material.

The volume resistivity ρ was measured by measuring the voltage at a room temperature of 20°C using the four-terminal method in accordance with the method specified in JIS C2525, with the distance between the voltage terminals set at 200 mm and the measurement current at 100 mA, and the volume resistivity ρ [μΩ cm] was calculated from the obtained value.

When the measured volume resistivity ρ was 80 μΩ·cm or more, the volume resistivity ρ was evaluated as being sufficiently large and excellent as a resistive material, with a rating of "◎". When the volume resistivity ρ was 70 μΩ·cm or more but less than 80 μΩ·cm, the volume resistivity ρ was evaluated as being large and good as a resistive material, with a rating of "○". On the other hand, when the volume resistivity ρ was less than 70 μΩ·cm, the volume resistivity ρ was evaluated as being small and poor as a resistive material, with a rating of "×". In this example, the evaluations were made with "◎" and "○" as pass levels. The results are shown in Table 3.

[5] Method for measuring thermoelectromotive force (EMF) against copper For the prepared copper alloy material, the obtained plate material having 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.

The copper thermoelectromotive force (EMF) of the test material was measured according to JIS C2527. More specifically, as shown in FIG. 2, the copper thermoelectromotive force (EMF) of the test material 11 was measured by using a fully annealed pure copper wire with a diameter of 1 mm as a standard copper wire 21, immersing a temperature measuring junction _P1 , to which one end of the test material 11 and the standard copper wire 21 were connected, in hot water kept warm in a thermostatic bath 41 at 80° C., and measuring the electromotive force when the reference junctions _P21 and _P22 , to which the other ends of the test material 11 and the standard copper wire 21 were connected to copper wires 31 and 32, respectively, were immersed in ice water at 0° C. kept cold in a freezing point device 42, using a voltage measuring device 43. The obtained electromotive force was divided by the temperature difference of 80° C. to obtain the copper thermoelectromotive force EMF (μV/° C.).

When the absolute value of the measured copper thermoelectromotive force (EMF) was 0.5 μV/℃ or less, the absolute value of the copper thermoelectromotive force (EMF) was evaluated as "◎", since the absolute value was sufficiently small and the material was deemed to be good as a resistive material. When the absolute value of the copper thermoelectromotive force (EMF) was greater than 0.5 μV/℃ and less than 1.0 μV/℃, the absolute value of the copper thermoelectromotive force (EMF) was small and the material was deemed to be good as a resistive material, since the absolute value was evaluated as "○". On the other hand, when the absolute value of the copper thermoelectromotive force (EMF) was greater than 1.0 μV/℃, the absolute value of the copper thermoelectromotive force (EMF) was large and the material was deemed to be poor as a resistive material, since the absolute value was evaluated as "×". The results are shown in Table 3.

[6] Method for measuring temperature coefficient of resistance (TCR) The prepared copper alloy material was cut into a plate having a thickness of 0.3 mm into a width of 10 mm and a length of 300 mm to prepare a test material.

The temperature coefficient of resistance (TCR) was measured by a four-terminal method according to the method specified in JIS C2525 and JIS C2526, with a voltage terminal distance of 200 mm and a measurement current of 100 mA, and the voltage was measured when the temperature of the test material was heated to 150 ° C., and the resistance value R _{150 ° C.} [μΩ] at 150 ° C. was obtained from the obtained value. Next, the voltage was measured when the temperature of the test material was cooled to 20 ° C., and the resistance value R _{20 ° C.} [μΩ] at 20 ° C. was obtained from the obtained value. Then, from the obtained resistance values R _{150 ° C.} and R _{20 ° C.} , the temperature coefficient of resistance (ppm / ° C.) was calculated from the formula TCR = {(R _{150 ° C.} [μΩ] - R _{20 ° C.} [μΩ]) / R _{20 ° C.} [μΩ]} × {1 / (150 [° C.] - 20 [° C.])} × 10 ⁶ .

When the absolute value of the measured temperature coefficient of resistance (TCR) was less than 50 ppm/℃, the absolute value of the temperature coefficient of resistance (TCR) was evaluated as "◎", since the absolute value of the temperature coefficient of resistance (TCR) was sufficiently small and the material was excellent as a resistive material. When the absolute value of the temperature coefficient of resistance (TCR) was between 50 ppm/℃ and 60 ppm/℃, the absolute value of the temperature coefficient of resistance (TCR) was evaluated as "◯", since the absolute value of the temperature coefficient of resistance (TCR) was small and the material was good as a resistive material. On the other hand, when the absolute value of the temperature coefficient of resistance (TCR) was greater than 60 ppm/℃, the absolute value of the temperature coefficient of resistance (TCR) was evaluated as "×", since the absolute value of the temperature coefficient of resistance (TCR) was too large and the material was poor as a resistive material. The results are shown in Table 3.

[7] Evaluation of reliability Furthermore, for the present invention examples 1 to 17 and the comparative examples 1 to 6, in order to examine the reliability when the copper alloy material is used as a resistance material for a long period of time, particularly the stability of electrical properties against heat, an accelerated test was performed on the test material after the volume resistivity was measured in the above-mentioned [4] Measurement of volume resistivity, by heating at 400 ° C for 2 hours. After the accelerated test by heating, the volume resistivity of the test material was measured in the same manner as in the above-mentioned [4] Measurement of volume resistivity, and the difference in volume resistivity obtained by subtracting the volume resistivity after heating from the volume resistivity before heating was obtained. Here, when the difference in volume resistivity obtained by subtracting the volume resistivity after heating from the volume resistivity before heating was 1.0 μΩ cm or less, the decrease in volume resistivity due to heating was small and the reliability was evaluated as "◎". Furthermore, when the difference in volume resistivity obtained by subtracting the volume resistivity after heating from the volume resistivity before heating exceeded 1.0 μΩ cm, the drop in volume resistivity due to heating was large, and the reliability was evaluated as relatively poor, and the evaluation was given as “○”. The results are shown in Table 3.

[8] Overall Evaluation Among these evaluation results, the size of the gouge generated in the copper alloy material during press punching, the volume resistivity ρ, the thermoelectromotive force against copper (EMF) and the temperature coefficient of resistance (TCR) were all evaluated as "◎", and the four characteristics of the size of the gouge generated in the copper alloy material during press punching, the volume resistivity ρ, the thermoelectromotive force against copper (EMF) and the temperature coefficient of resistance (TCR) were evaluated as "◎". In addition, when at least one of these four evaluation results was evaluated as "○" and the remaining was evaluated as "◎", these four characteristics were at least good and evaluated as "○". On the other hand, when the evaluation result of at least one of the press punching workability, the volume resistivity ρ, the thermoelectromotive force against copper (EMF) and the temperature coefficient of resistance (TCR) was "×", at least one of these four characteristics was evaluated as "×" as failing. The results are shown in Table 3.

From the results in Tables 1 to 3, the copper alloy materials of Examples 1 to 17 of the present invention have alloy composition and maximum orientation density values within the appropriate ranges of the present invention, and the ratio of the area of the overlapping portion 9 of the copper alloy material 1 and the rectangle R to the area of the rectangle R is all evaluated as "◎" or "◯", so that the gouge formed on the punched surface is evaluated as small. In addition, the copper alloy materials of Examples 1 to 17 of the present invention were also evaluated as "◎" or "◯" for the volume resistivity ρ, thermoelectromotive force to copper (EMF), and temperature coefficient of resistance (TCR).

On the other hand, the copper alloy materials of Comparative Examples 1 and 2 had large maximum orientation densities at φ1 = 0-90°, Φ = 0-90°, and φ2 = 15°, 20°, and 25° when the crystal orientation distribution function (ODF) was expressed as Euler angles, which were outside the appropriate range of the present invention. Therefore, the copper alloy materials of Comparative Examples 1 and 2 were evaluated as "X" for the size of the gouge that occurred in the copper alloy material during press punching.

In addition, the copper alloy material of Comparative Example 3 had a low Ni content and the alloy composition was outside the appropriate range of the present invention. Therefore, the copper alloy material of Comparative Example 3 was rated as "X" in terms of thermal electromotive force (EMF) against copper.

In addition, the copper alloy material of Comparative Example 4 had low contents of both Mn and Ni, and the alloy composition was outside the appropriate range of the present invention. Therefore, the copper alloy material of Comparative Example 4 was evaluated as "x" for volume resistivity ρ. In particular, the copper alloy material of Comparative Example 4 had a low Mn content, and therefore the evaluation result of volume resistivity ρ was "x".

In addition, the copper alloy material of Comparative Example 5 had a high Mn content and the alloy composition was outside the appropriate range of the present invention. Therefore, the copper alloy material of Comparative Example 5 was rated as "X" in terms of copper thermoelectromotive force (EMF).

In addition, the copper alloy material of Comparative Example 6 had a high Ni content, and the alloy composition was outside the appropriate range of the present invention. Therefore, the copper alloy material of Comparative Example 6 was rated as "X" in terms of copper thermoelectromotive force (EMF) and temperature coefficient of resistance (TCR).

From these results, it was confirmed that the copper alloy material of the present invention has small gouges during press punching when the maximum orientation density of the alloy composition and the crystal orientation distribution function (ODF) expressed as Euler angles (φ1, Φ, φ2) is within the appropriate range of the present invention. At the same time, it was confirmed that the volume resistivity ρ, thermoelectromotive force (EMF) to copper, and temperature coefficient of resistance (TCR) of the copper alloy material of the present invention are at least good.

FIG. 3 shows a graph of the crystal orientation distribution function (ODF) of the copper alloy material of Example 14 of the present invention, expressed as Euler angles (φ1, Φ, φ2), with φ1 on the horizontal axis and Φ on the vertical axis, showing the orientation density in the ranges of φ1=0-90° and Φ=0-90°, where FIG. 3(a) shows the graph when φ2=15°, FIG. 3(b) shows the graph when φ2=20°, and FIG. 3(c) shows the graph when φ2=25°. From this graph, it can be seen that the maximum orientation density of the copper alloy material of Example 14 of the present invention is 3.1 when φ1=0-90°, Φ=0-90°, and φ2 is 15°, 20°, and 25° (the measured value of the maximum orientation density was rounded off to one decimal place).

FIG. 4 shows scanning electron microscope (SEM) photographs of the punched copper alloy materials of the present invention and comparative examples, observed in a direction parallel to the cut surface as in FIG. 1, after press punching to show the outline shape of the cut surface (right edge portion) of the punched copper alloy materials. Here, FIG. 4(a) is an SEM photograph of the outline shape of the cut surface of the copper alloy material of present invention example 5, and FIG. 4(b) is an SEM photograph of the outline shape of the cut surface of the copper alloy material of comparative example 1. From these SEM photographs, it was confirmed that the copper alloy material of the present invention has smaller gouges on the fracture surface that occur during press punching compared to the copper alloy material of the comparative example.

Furthermore, in invention examples 1 to 4, 6, 7, 9 to 11, and 13 to 17, the Fe content was set to 0.20 mass% or less, which improved the stability of the electrical characteristics against heat, etc., and resulted in a reliability evaluation result of "◎" compared to invention examples 5, 8, and 12, which had an Fe content of 0.30 mass% or more and were evaluated as "◯" in the reliability evaluation result.

In addition, in invention examples 4 to 17, the absolute value of the temperature coefficient of resistance (TCR) was smaller due to the inclusion of one or both of Fe and Co, compared to invention examples 1 to 3, which were evaluated as "good" for the temperature coefficient of resistance (TCR), and therefore the temperature coefficient of resistance (TCR) was evaluated as "◎".

REFERENCE SIGNS LIST 1 Copper alloy material 1a Upper surface of copper alloy material 1b Lower surface of copper alloy material 2 Cut surface 3 Sagging 4 Shear surface 5 Fracture surface 6 Gouge on punched surface 7 Burr 8 Boundary 9 Overlapping portion of copper alloy material and rectangle 11 Test material 21 Standard copper wire 31, 32 Copper wire 41 Thermostatic chamber 42 Freezing point device 43 Voltage measuring instrument _P1 Temperature measuring junction _P21 , _P22 Reference junction X Direction perpendicular to cut surface Y Thickness direction

Claims (6)

1. A copper alloy material having an alloy composition containing Mn: 20.0 mass% or more and 35.0 mass% or less, and Ni: 6.5 mass% or more and 17.0 mass% or less, with the balance being Cu and unavoidable impurities,
   The copper alloy material has a maximum orientation density of 6.0 or less when a crystal orientation distribution function (ODF) obtained by crystal orientation analysis by a SEM-EBSD method is expressed in terms of Euler angles (φ1, Φ, φ2) in a longitudinal section including the stretching direction and thickness direction of the copper alloy material, and the maximum value of the orientation density is 6.0 or less when φ1=0 to 90°, Φ=0 to 90°, and φ2 is 15°, 20°, and 25°.
2. The copper alloy material according to claim 1, wherein the average grain size of the grains in the longitudinal section obtained from crystal orientation analysis data by the SEM-EBSD method is 20 μm or less, and the standard deviation of the average grain size is 10 μm or less.
3. The alloy composition is
   The copper alloy material according to claim 1, further containing one or both of Fe: 0.01 mass% or more and 0.50 mass% or less, and Co: 0.01 mass% or more and 2.00 mass% or less.
4. The alloy composition is
   Sn: 0.01% by mass or more and 5.00% by mass or less,
   Zn: 0.01% by mass or more and 5.00% by mass or less,
   Cr: 0.01% by mass or more and 0.50% by mass or less,
   Ag: 0.01% by mass or more and 0.50% by mass or less,
   Al: 0.01% by mass or more and 1.00% by mass or less,
   Mg: 0.01% by mass or more and 0.50% by mass or less,
   The copper alloy material according to claim 1, further comprising at least one selected from the group consisting of Si: 0.01 mass% or more and 0.50 mass% or less, and P: 0.01 mass% or more and 0.50 mass% or less.
5. A resistor material for resistors, comprising the copper alloy material according to any one of claims 1 to 4.
6. A resistor that is a shunt resistor or a chip resistor, comprising the resistor material according to claim 5.

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