TWI892375B - Copper alloy material, resistor material for resistor using the same, and resistor - Google Patents

Abstract

The present invention provides a copper alloy material, a resistor material for a resistor using the copper alloy material, and a resistor. The copper alloy material has the following characteristics: small scratches on the copper alloy material during stamping, sufficiently high volume resistivity, a negative temperature coefficient of resistance (TCR) with a small absolute value, and a small absolute value of the copper thermoelectromotive force (EMF). The copper alloy material has the following alloy composition: containing 20.0 mass% to 35.0 mass% of Mn and 6.5 mass% to 17.0 mass% of Ni, with the remainder consisting of Cu and inevitable impurities. In a longitudinal cross-section of the copper alloy material including the extension direction and the thickness direction, when the orientation distribution function (ODF) obtained by crystal orientation analysis using a SEM-EBSD method is expressed as Euler angles (φ1, Φ, φ2), the maximum orientation density is 6.0 or less when φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 = 15°, 20°, and 25°.

Description

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

The present invention relates to a copper alloy material, a resistor material for a resistor using the copper alloy material, and a resistor

The metal materials used in resistors are expected to maintain stable resistance even with changes in ambient temperature. Therefore, resistor materials are required to have a low absolute value of the temperature coefficient of resistance (TCR), an indicator of the stability of resistance with respect to temperature changes. The temperature coefficient of resistance expresses the change in resistance due to temperature in parts per million (ppm) per 1°C and can be expressed as follows: TCR (× ^10-6 /°C) = {( _RR0 )/ _R0 } × {1/( _TT0 )} × ^106. In this formula, T represents the test temperature (°C), _T0 represents the reference temperature (°C), R represents the resistance value (Ω) at the test temperature T, and _R0 represents the resistance value (Ω) at the reference temperature _T0 . In particular, Cu-Mn-Ni alloy and Cu-Mn-Sn alloy have very low TCR and are therefore widely used as alloy materials constituting resistor materials.

However, when using Cu-Mn-Ni and Cu-Mn-Sn alloys as resistor materials, for example, to design a resistor with a specified resistance value by forming a circuit (pattern) using a resistive material, the volume resistivity is as low as less than ⁵⁰ × ^10-8 (Ω·m), so the cross-sectional area of the resistive material must be reduced to increase the resistor's resistance value. Such resistors have the following disadvantage: when a large current flows temporarily in the circuit, or when a relatively large current flows continuously, the Joule heat generated in the small cross-sectional area of the resistive material increases, causing it to heat up, resulting in the resistive material becoming susceptible to thermal cracking (melting).

Therefore, in order to prevent the cross-sectional area of the resistor material from decreasing, a resistor material with a higher volume resistivity is being sought.

For example, Patent Document 1 states that, by configuring the mass fraction of Mn and the mass fraction of Ni in a copper alloy containing Mn in a range of not less than 23 mass % and not more than 28 mass % and Ni in a range of not less than 9 mass % and not more than 13 mass % so that the thermoelectric motive force relative to copper is less than ±1 μV/°C at 20°C, a copper alloy can be obtained. The copper alloy has a high electrical resistance (volume resistivity ρ) of not less than ⁵⁰ × ^10-8 [Ω·m], a low thermoelectric motive force relative to copper (EMF relative to copper), a low temperature coefficient of resistance, and high stability of inherent resistance with respect to time (time invariance).

Furthermore, Patent Document 2 states that a resistor alloy containing copper, manganese, and nickel, containing Mn in an amount ranging from 33% to 38% by mass and Ni in an amount ranging from 8% to 15% by mass, can achieve properties (particularly relative resistance) similar to those of nickel-chromium alloys while also producing a copper-manganese-nickel alloy with superior workability compared to nickel-chromium alloys. [Prior Art Document] (Patent Document)

Patent Document 1: Japanese Patent Publication No. 2016-528376 Patent Document 2: Japanese Patent Application Laid-Open No. 2021-161512

[Problem to be Solved by the Invention] With the recent trend toward miniaturization and high integration of electrical and electronic components, resistors and the resistance materials used in them have also been miniaturized. Resistor materials used in resistors are generally formed by cutting processes such as stamping. Therefore, to minimize variations in resistance values, copper alloy materials are required to have excellent stamping properties. In particular, a method is sought to minimize resistance variations by forming the cut surface, which serves as the punching surface, at a fixed position during stamping of the copper alloy material.

However, copper alloys containing high concentrations of Mn and Ni to increase their volume resistivity experience continuous solid solution strengthening, resulting in high mechanical strength and strong interactions between the atoms that make up the copper alloy. On the other hand, these copper alloys are susceptible to scratching in the cut surface, particularly the fracture surface, when punching is performed under pressure after forming the sheet. These scratches in the fracture surface partially reduce the cross-sectional area of the resistor material obtained by punching near the cut surface, potentially compromising the resistance precision of the resistor material.

Furthermore, in recent years, resistors such as shunt resistors and chip resistors in electric vehicle electronic systems have been required to have not only a high volume resistivity, ρ, but also high precision to withstand higher temperature environments. Furthermore, copper alloys used in such resistors are also required to withstand these higher temperature environments. More specifically, when considering a high volume resistivity, ρ, and operating environments over a wide temperature range from room temperature to high temperatures, a copper alloy material with a negative temperature coefficient of resistance (TCR) and a low absolute value, as well as a low absolute value of the copper thermoelectromotive force (EMF), is required.

Therefore, the present invention aims to provide a copper alloy material, a resistor material for a resistor using the copper alloy material, and a resistor. The copper alloy material has the following characteristics: minimal scratching on the punched surface during punching, a sufficiently high volume resistivity, a negative temperature coefficient of resistance (TCR) with a low absolute value, and a low absolute value of the copper thermoelectromotive force (EMF). [Solution]

The inventors have discovered a copper alloy material having the following 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 remainder being composed of Cu and unavoidable impurities, and having an alloy composition with an Euler angle ( When the orientation distribution function (ODF) is represented by (φ1, Φ, φ2), 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°. By using this copper alloy material, for example, a copper alloy material can be obtained, which has a sufficiently high volume resistivity ρ as a resistor material, and a negative temperature coefficient of resistance (TCR) with a small absolute value, taking into account the use environment within a wide temperature range from room temperature (e.g., 20°C) to high temperature (e.g., 150°C), and a small absolute value of the thermoelectromotive force (EMF) of copper. This has led to the completion of the present invention.

In order to achieve the above-mentioned object, the main components of the present invention are as follows. (1) A copper alloy material having the following 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 remainder consisting of Cu and unavoidable impurities, wherein in a longitudinal cross-section of the copper alloy material including the extension direction and the thickness direction, when the orientation distribution function (ODF) obtained by crystal orientation analysis by SEM-EBSD method is expressed as Euler angles (φ1, Φ, φ2), 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 as described in (1) above, wherein, in the longitudinal cross section, the average crystal grain size of the grains obtained from the crystal orientation analysis data by the SEM-EBSD method is 20 μm or less and the standard deviation of the average crystal grain size is 10 μm or less. (3) The copper alloy material as described in (1) or (2) above, wherein the alloy composition further contains one or both of 0.01 mass% to 0.50 mass% of Fe and 0.01 mass% to 2.00 mass% of Co. (4) The copper alloy material as described in any one of (1) to (3) above, wherein the alloy composition further contains at least one selected from the group consisting of: 0.01 mass% to 5.00 mass% Sn, 0.01 mass% to 5.00 mass% Zn, 0.01 mass% to 0.50 mass% Cr, 0.01 mass% to 0.50 mass% Ag, 0.01 mass% to 1.00 mass% Al, 0.01 mass% to 0.50 mass% Mg, 0.01 mass% to 0.50 mass% Si, and 0.01 mass% to 0.50 mass% P. (5) A resistor material for a resistor, which is composed of the copper alloy material described in any one of (1) to (4) above. (6) A resistor, which is a shunt resistor or a chip resistor, which has the resistor material for a resistor described in (5) above. [Effects of the Invention]

According to the present invention, a copper alloy material, a resistor material for a resistor using the copper alloy material, and a resistor can be provided. The copper alloy material has the following characteristics: small scratches on the punched surface produced during punching, a sufficiently high volume resistivity, a negative temperature coefficient of resistance (TCR) with a small absolute value, and a small absolute value of the thermoelectromotive force (EMF) of copper.

The following describes in detail the preferred embodiments of the copper alloy material of the present invention. Furthermore, regarding the composition of the alloy of the present invention, "mass %" may sometimes be expressed simply as "%.

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

Thus, in the copper alloy material according to the present invention, for a copper alloy material containing 20.0 mass% to 35.0 mass% Mn and 6.5 mass% to 17.0 mass% Ni, when the orientation distribution function (ODF) is expressed in terms of Euler angles (φ1, Φ, φ2), the maximum value of the orientation density when φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 = 15°, 20°, and 25° is set to 6.0 or less. This prevents grains having similar mechanical properties from becoming densely packed to an unnecessary degree, thereby suppressing gouges on the fracture surface generated during stamping.

In addition, the copper alloy material according to the present invention contains Mn in a range of 20.0 mass% to 35.0 mass% and Ni in a range of 5.0 mass% to 17.0 mass%. This allows the volume resistivity ρ to be increased while reducing 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 also reducing the absolute value of the thermoelectric motive force of copper. Furthermore, in the copper alloy material according to the present invention, the absolute value of the copper-copper thermoelectromotive force (EMF) (hereinafter sometimes simply referred to as "copper-copper thermoelectromotive force") generated between 20°C and 80°C is reduced, thereby enabling the high-precision manufacture of resistors even in high-temperature environments.

In this regard, in order to reduce the absolute value of the thermoelectric power of copper in the copper alloy described in Patent Document 1, it is necessary to increase the Ni content. In this case, the absolute value of the temperature coefficient of resistance (TCR) tends to increase. In addition, the temperature dependence of the resistance of the copper alloy described in Patent Document 1 is shown in Figure 3 of Patent Document 1. For example, in the temperature range of 20°C to 150°C, which includes the higher temperature range, the temperature coefficient of resistance (TCR) becomes a large and negative number. Therefore, there is a tendency for the resistance value to be easily distorted in the high temperature range. However, the copper alloy material according to the present invention can suppress the increase in the absolute value of the temperature coefficient of resistance (TCR) in the temperature range from 20°C to 150°C. Therefore, it is also excellent in the following aspects: while having a sufficiently high volume resistivity ρ as a resistor material, the absolute value of the temperature coefficient of resistance (TCR) is small when considering the usage environment within a wide temperature range from room temperature (e.g., 20°C) to high temperature (e.g., 150°C), and the absolute value of the thermoelectromotive force (EMF) to copper is small.

As a result, the copper alloy material according to the present invention can provide a copper alloy material, a resistor material for a resistor using the copper alloy material, and a resistor. The copper alloy material has the following characteristics: small scratches on the punched surface generated during punching, a sufficiently high volume resistivity ρ, a negative temperature coefficient of resistance (TCR) with a small absolute value, and a small absolute value of the thermoelectromotive force (EMF) of copper.

[1] Composition of Copper Alloy Material ＜Required Additives＞ The alloy composition of the copper alloy material of the present invention contains 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 as required additives.

(Mn: 20.0 mass% or more and 35.0 mass% or less) 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 is preferable to contain 20.0 mass % or more of Mn, more preferably 22.0 mass % or more, and still 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% by mass, the melting point of the copper alloy material will decrease, making it difficult to control the production of the copper alloy material, especially the hot processing, and it will be difficult to obtain uniform characteristics. Furthermore, if the Mn content exceeds 35.0 mass%, the absolute value of the copper thermoelectric force (EMF) tends to increase. Therefore, the Mn content is set within the range of 20.0 mass% to 35.0 mass%.

(Ni: 6.5% by mass or more and 17% by mass or less) Nickel (nickel) is an element that adjusts the EMF relative to copper toward positive values. To achieve this effect, a Ni content of 6.5% by mass or more is preferred. On the other hand, a Ni content exceeding 17% by mass makes it difficult to achieve a uniform structure, and the volume resistivity ρ and EMF relative to copper may change. Furthermore, a Ni content exceeding 17% by mass tends to increase the EMF relative to copper to a large positive value, and the absolute value of the temperature coefficient of resistance (TCR) tends to increase. Therefore, from the perspective of obtaining a copper alloy material having desired properties or from the perspective of obtaining a copper alloy material that is easily manufactured, the Ni content is set within the range of 6.5 mass% to 17.0 mass%, preferably 6.5 mass% to 12.0 mass%, and even more preferably 6.5 mass% to 9.0 mass%.

<First Optional Additive> The alloy composition of the copper alloy material of the present invention can further include, as optional additives, one or both of Fe (0.01 mass% to 0.50 mass%) and Co (0.01 mass% to 2.00 mass%). In particular, the inclusion of one or both of Fe and Co can further reduce the absolute value of the temperature coefficient of resistance (TCR).

(Fe: 0.01% by mass or more and 0.50% by mass or less) Fe (iron) is an element that adjusts the thermoelectric force (EMF) of copper toward a positive value. To achieve this effect, an Fe content of 0.01% by mass or more is preferred. On the other hand, if the Fe content exceeds 0.50% by mass, a uniform structure becomes difficult to achieve, and electrical properties tend to vary. In particular, to further enhance the stability of electrical properties against heat and other factors, and further improve reliability when used as resistor materials over a long period of time, the Fe content is preferably set to 0.20% by mass or less. In particular, to further enhance reliability over a long period of use, the inclusion of Co is preferable to the inclusion of Fe. That is, it is preferred to contain only the necessary amount of Co (described later) without Fe. Therefore, the Fe content is preferably within a range of 0.01 mass% to 0.50 mass%, and more preferably within a range of 0.01 mass% to 0.20 mass%.

(Co: 0.01% by mass or more and 2.00% by mass or less) Co (cobalt) is an element that adjusts the thermoelectric motive force (EMF) of copper toward a positive value. To achieve this effect, a Co content of 0.01% by mass or more is preferred. On the other hand, if the Co content exceeds 2.00% by mass, a uniform structure becomes difficult to achieve, and electrical properties tend to vary. Therefore, the Co content is preferably within the range of 0.01% by mass or more and 2.00% by mass or less.

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

(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, a Sn content of 0.01% by mass or more is preferred. On the other hand, by keeping the Sn content to 5.00% by mass or less, the reduction in manufacturability caused by embrittlement of the copper alloy material can be minimized.

(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, a Zn content of 0.01% by mass or more is preferred. However, because it can adversely affect the volume resistivity ρ and the stability of the resistor's electrical properties, such as copper thermoelectromotive force (EMF), the Zn content is preferably kept to 5.00% by 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, a Cr content of 0.01% by mass or more is preferred. However, because it can adversely affect the volume resistivity ρ and the stability of the resistor's electrical properties, such as copper thermoelectrodynamic force (EMF), the Cr content is preferably kept to 0.50% by mass or less.

(Ag: 0.01% by mass or more and 0.50% by mass or less) Ag (silver) is a component that can be used to adjust the volume resistivity ρ. To achieve this, an Ag content of 0.01% by mass or more is preferred. However, because it can adversely affect the volume resistivity ρ and the stability of the resistor's electrical properties, such as copper thermoelectromotive force (EMF), the Ag content is preferably kept to 0.50% by 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, an Al content of 0.01% by mass or more is preferred. On the other hand, since it can embrittle copper alloy materials, the Al content is preferably kept to 1.00% by 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, a Mg content of 0.01% by mass or more is preferred. On the other hand, since it can embrittle copper alloy materials, the Mg content is preferably kept to 0.50% by mass or less.

(Si: 0.01% by mass or more and 0.50% by mass or less) Silicon (Si) is a component that can be used to adjust the volume resistivity ρ. To achieve this effect, a Si content of 0.01% by mass or more is preferred. On the other hand, because it can embrittle the copper alloy material, the Si content is preferably kept to 0.50% by 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, a P content of 0.01% by mass or more is preferred. On the other hand, since it can embrittle the copper alloy material, the P content is preferably kept to 0.50% by mass or less.

(Total Amount of Second Optional Additives: 0.01% by mass or more and 5.00% by mass or less) To maximize the effects of the second optional additives consisting of at least one element selected from the group consisting of Sn, Zn, Cr, Ag, Al, Mg, Si, and P, the total amount of these second optional additives is preferably 0.01% by mass or more. However, excessive amounts of these second optional additives can destabilize electrical properties and hinder copper alloy production. Therefore, the total amount is preferably 5.00% by mass or less.

<Remainder: Cu and Unavoidable Impurities> In addition to the required components and optional additives listed above, the remainder consists of Cu (copper) and unavoidable impurities. The term "unavoidable impurities" here refers to impurities that are present in copper-based products, either in the raw materials or unavoidably introduced during the manufacturing process. These impurities are generally undesirable, but are tolerated because they are present in trace amounts and do not adversely affect the properties of the copper-based product. Examples of unavoidable impurities include non-metallic elements such as sulfur (S) and metallic elements such as antimony (Sb). Furthermore, the upper limit of the content of these ingredients can be set as: 0.05 mass% of each of the above ingredients, and the total amount of the above ingredients is 0.10 mass%.

[2] The maximum value of the orientation density when φ1 = 0-90°, Φ = 0-90°, and φ2 = 15°, 20°, and 25° when the orientation distribution function (ODF) is expressed as Euler angles The copper alloy material of the present invention, in a longitudinal cross-section including the extension direction and the thickness direction of the copper alloy material, when the orientation distribution function (ODF) is expressed as Euler angles (φ1, Φ, φ2) obtained by crystal orientation analysis using the SEM-EBSD method, the maximum value of the orientation density when φ1 = 0-90°, Φ = 0-90°, and φ2 = 15°, 20°, and 25° is 6.0 or less. Copper alloy materials containing a large amount of Mn and Ni as in the present invention tend to be oriented in specific orientations such as S orientation and copper orientation. Here, if a particular orientation becomes dominant, grains with similar mechanical characteristics become densely packed. In this case, gouges on the fracture surface during punching tend to become larger. Therefore, to suppress gouges on the fracture surface during punching, it is necessary to suppress the grains from aligning in a particular orientation. Therefore, when expressing the orientation distribution function (ODF) in terms of Euler angles (φ1, Φ, φ2), the maximum values of the orientation density are set to 6.0 or less for φ1 = 0-90°, Φ = 0-90°, and φ2 = 15°, 20°, and 25°, respectively. By setting the maximum orientation density within this range to 6.0 or less, grains oriented in specific orientations, such as S and copper, are prevented from accumulating unnecessarily. Consequently, grains with similar mechanical characteristics are less densely packed. Consequently, the chipping of the fracture surface during punching is suppressed, resulting in a flatter cut surface. As a result, even near the cut surface, the cross-sectional area of the resistor material obtained by punching is less susceptible to damage from chipping, resulting in a suitable copper alloy material that can produce resistors with higher precision.

Therefore, from the perspective of suppressing the scratches on the fracture surface generated during punching and obtaining a copper alloy material suitable for obtaining a resistor with higher precision, it is preferred that the maximum value of the orientation density when the orientation distribution function (ODF) is expressed as Euler angles (φ1, Φ, φ2) is 6.0 or less when φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 is 15°, 20°, and 25°, and is more preferably 5.7 or less.

The maximum values of the orientation density when expressing the Orientation Distribution Function (ODF) in terms of Euler angles (φ1, Φ, φ2) are obtained from crystal orientation analysis using the SEM-EBSD method, when φ1 = 0-90°, Φ = 0-90°, and φ2 = 15°, 20°, and 25°.

Here, crystal orientation analysis data using the SEM-EBSD method can be obtained by mirror-polishing a cross-section parallel to the extension direction of the copper alloy material to create a cross-section sample. The sample is then observed using a field-emission scanning electron microscope (FE-SEM) and subjected to EBSD (electron backscatter diffraction) analysis. The EBSD measurement can be performed over an area of 0.2 ^mm² or greater, with a step size of 0.5 μm.

Based on the EBSD measurement results, the maximum orientation density can be determined using an ODF map obtained using the analysis software "OIM ANALYSIS." More specifically, intensity calculations were performed using the Harmonic Series Expansion method, with the Series Rank set to 16 and the Gaussian Half-Width set to 5°. The results were then passed to the Enforce Orthotropic Sample Symmetry option to perform a mass structure analysis. An ODF spectrum showing the intensity distribution of crystal orientations expressed in terms of Euler angles (φ1, Φ, φ2) was plotted. This spectrum allowed the maximum orientation density to be determined for φ1 = 0-90°, Φ = 0-90°, and φ2 = 15°, 20°, and 25°.

Furthermore, when the orientation distribution function (ODF) is expressed in terms of Euler angles (φ1, Φ, φ2), the maximum values of the orientation density when φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 is 15°, 20°, and 25° are expressed as relative values, which are relative to the case where the density of grains oriented at the Euler angle (φ1, Φ, φ2) is set to 1 when all grains are randomly oriented.

[3] Average grain size and standard deviation of the copper alloy material's grains The copper alloy material of the present invention preferably has an average grain size of 20 μm or less and a standard deviation of 10 μm or less. Thus, when the copper alloy material is punched, the scratches on the fracture surface of the punching process can be further reduced.

Here, the average grain size and standard deviation of the copper alloy material's grains can be obtained from the crystal orientation analysis data obtained using the SEM-EBSD method described above for a longitudinal cross-section of the copper alloy material, including the extension and thickness directions. More specifically, they can be determined from a graph of grain size (diameter) obtained using the analysis software "OIM ANALYSIS." The average grain size and standard deviation calculated using the Area Fraction (Area Fraction) can then be used as the average grain size and standard deviation.

[4] Shape of copper alloy material The shape of the copper alloy material of the present invention is not particularly limited, but from the perspective of facilitating the hot working or cold working steps described later, and cutting by press working, a plate is preferred. Here, the copper alloy material formed by rolling, such as a plate, can have the rolling direction set as the extension direction. On the other hand, the copper alloy material of the present invention can be a wire, a square wire, a strip, a bar, or a rod, and by forming such shapes using the copper alloy material of the present invention, it can be easy to perform cutting processing on the end. Here, in the copper alloy material of such shapes formed by drawing, pulling, or extrusion, any one of the drawing direction, the pulling direction, or the extrusion direction can be set as the extension direction.

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

As an example of a method for producing a copper alloy material of the present invention, a copper alloy raw material having an alloy composition substantially identical to that of 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 this order, and then the cold working step and the hot treatment step are repeated two or more times, preferably four or more times. In the homogenization heat treatment step [step 2], the heating temperature is set within a range of 750°C to 900°C, and the temperature holding time at the heating temperature is set within a range of 10 minutes to 10 hours. Furthermore, after the first heat treatment step [Step 4], the cold working step is repeated, and the total working rate is set within the range of 40% to 65%. Furthermore, after the first heat treatment step [Step 4], the hot working step is repeated, and the heating temperature is set within the range of 650°C to 850°C, and the heating is performed so that the heating temperature is reached within 15 seconds from room temperature, and the temperature holding time at the heating temperature is set within the range of 1 second to 40 seconds.

(i) Casting Step [Step 1] The casting step [Step 1] involves melting the copper alloy raw material having the above-described alloy composition in an inert gas atmosphere or in a vacuum using a high-frequency melting furnace. The material is then cast to produce an ingot of a specific shape (e.g., 30 mm to 300 mm thick, 500 mm wide, and 3000 mm long). The alloy composition of the copper alloy raw material may not always be identical to that of the copper alloy sheet due to the attachment or volatilization of additives in the melting furnace during the various manufacturing steps. However, the resulting copper alloy sheet still possesses a substantially identical alloy composition to that of the copper alloy material.

(ii) Homogenization Heat Treatment Step [Step 2] The homogenization heat treatment step [Step 2] is a step in which the casting, after the casting step [Step 1], is subjected to heat treatment for homogenization. To suppress grain coarsening, the heat treatment conditions in the homogenization heat treatment step [Step 2] are preferably set to 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.

(iii) Hot Working Step [Step 3] The hot working step [Step 3] involves heating the casting that has undergone the homogenization heat treatment step [Step 2] and performing elongation processes such as rolling and wire drawing until it reaches a specific thickness, thereby producing a hot-rolled material. The conditions for the hot working step [Step 3] are preferably a heating temperature between 700°C and 850°C, and may be the same as the heating temperature in the homogenization heat treatment step [Step 2]. Furthermore, the processing rate in the hot working step [Step 3] is preferably 50% or greater.

Here, "processing rate" is the value expressed as a percentage by subtracting the cross-sectional area after processing from the cross-sectional area before processing (e.g., rolling and drawing), dividing the result by the cross-sectional area before processing, and multiplying by 100. This value can be expressed as follows: [Processing rate] (%) = {([Cross-sectional area before processing] - [Cross-sectional area after processing]) / [Cross-sectional area before processing]} × 100

The hot rolled material in the hot working step [Step 3] is preferably cooled. Water cooling is preferred for cooling the hot rolled material, as it facilitates obtaining a fine and uniform crystalline structure with an average grain size of 50 μm or less. On the other hand, while slowing the cooling rate after the hot working step can allow grain growth to occur, it makes it difficult to maintain a uniform temperature throughout the hot rolled material, resulting in a poorly uniform structure.

(iv) First Heat Treatment Step [Step 4] Next, the water-cooled hot-rolled material is subjected to the first heat treatment step [Step 4] to adjust the average grain size. Here, the step involves heat treatment at a temperature of 650°C to 850°C for 2 to 5 hours to adjust the average grain size to over 100 μm. By using a heat treatment furnace to achieve a uniform structure with an average grain size exceeding 100 μm, the development of the aggregate structure formed by subsequent processing is inhibited, thereby reducing the maximum orientation density.

Here, the hot-rolled material after the first heat treatment step [Step 4] can be subjected to surface cutting to remove the surface. This surface cutting can remove surface oxide films and defects generated during the hot working step [Step 3]. The conditions for surface cutting are generally applicable and are not particularly limited. The amount of surface removed from the hot-rolled material by surface cutting can be appropriately set based on the conditions of the hot working step [Step 3], for example, to approximately 0.5 mm to 4 mm from the surface of the hot-rolled material.

(v) Repeated Cold Working and Heat Treatment Steps After the first heat treatment step [Step 4], the hot-rolled material is subjected to two or more repeated cold working and heat treatment steps until the thickness and dimensions of the product are achieved. The cold working step involves stretching processes such as rolling and drawing while cooling, and the heat treatment step involves heat treatment. More specifically, for the hot-rolled material that has been subjected to the first heat treatment step [step 4] after hot working, at least the first cold working step, the first heat treatment step, the second cold working step, and the second heat treatment step are performed, and the cold working step and the heat treatment step at this time can be sequentially set as 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]. Furthermore, a third cold working step and a heat treatment step can be performed on the cold rolled material after the third heat treatment step [step 8], and the cold working step and the heat treatment step at this time can be set as the third cold working step [step 9] and the fourth heat treatment step [step 10], respectively. Furthermore, a fourth cold working step and a heat treatment step can be performed on the cold rolled material after the fourth heat treatment step [step 10], and the cold working step and the heat treatment step at this time can be set as the fourth cold working step [step 11] and the fifth heat treatment step [step 12], respectively. By repeating the cold working and heat treatment steps two or more times on the hot-rolled material after the first heat treatment step [Step 4], the maximum orientation density when expressing the Orientation Distribution Function (ODF) in terms of Euler angles (φ1, Φ, φ2) is reduced when φ1 = 0-90°, Φ = 0-90°, and φ2 = 15°, 20°, and 25°. This reduces the risk of gouges on the punched surface during punching.

At this time, the total working ratio 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] is set to be within the range of 40% or more and 65% or less. Here, when the cold working steps after the second cold working step [step 7] are not performed, or when the total working ratio in at least any 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] is less than 40%, recrystallization becomes difficult to occur, and thus it is difficult to obtain a uniform structure. Furthermore, if the total working ratio in 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 value of the orientation density when the orientation distribution function (ODF) is expressed as Euler angles (φ1, φ, φ2) at φ1 = 0 to 90°, φ = 0 to 90°, and φ2 of 15°, 20°, and 25° becomes unnecessarily large. It is particularly preferred 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] be 60% or less.

In addition, 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: the heating temperature is set in the range of 650°C to 850°C, and the heating is performed in a manner such that the heating temperature is reached within 15 seconds from room temperature and the temperature holding time at the heating temperature is set in the range of 1 second to 40 seconds. Here, if the heat treatment time exceeds 1 minute, the standard deviation of the grain size may become larger. Therefore, from the perspective of adjusting the grain size to an appropriate range and obtaining a uniform crystal structure, it is better to shorten the time to reach the heating temperature and also shorten the temperature holding time at the heating temperature.

[6] Application of copper alloy materials The copper alloy material of the present invention is extremely useful as a resistor material for resistors such as shunt resistors or chip resistors. That is, the resistor material for the resistor is preferably composed of the above-mentioned copper alloy material. In addition, the resistor such as the shunt resistor or chip resistor preferably has a resistor material for the resistor composed of the above-mentioned copper alloy material.

While the embodiments of the present invention have been described above, the present invention is not limited to the aforementioned embodiments. It encompasses all aspects encompassing the concepts of the present invention and the scope of the invention application, and various modifications are possible within the scope of the present invention. [Examples]

Next, in order to further clarify the effects of the present invention, examples of the present invention and comparative examples are described, but the present invention is not limited to these embodiments.

(Examples 1 to 17 of the present invention and Comparative Examples 1 to 6) A casting having a thickness of 30 mm was obtained by performing the casting step [1] by melting a copper alloy raw material having the alloy composition shown in Table 1 and then cooling it from the molten metal. Here, the alloy composition of Comparative Example 1 is the same as that of the copper alloy described in the above-mentioned Patent Document 1 and Example 2 of the above-mentioned Patent Document 2.

The casting was subjected to a homogenization heat treatment step [Step 2] at a heating temperature of 800°C and a holding time of 5 hours. Subsequently, a hot working step [Step 3] was performed, followed by cooling to room temperature by water cooling to obtain a hot rolled material. The hot working step [Step 3] was performed at a heating temperature of 800°C and along the longitudinal direction until the total processing rate reached 67% (the thickness before processing was 30 mm and the thickness after processing was 10 mm).

In Examples 1 to 17 of the present invention and Comparative Examples 1, 3 to 6, a first heat treatment step [Step 4] was performed on the hot-rolled material after water cooling to promote grain growth. This first heat treatment step [Step 4] was performed at a heating temperature of 800°C and a holding time of 4 hours. On the other hand, in 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 formed on the surface, face cutting was performed, removing 1 mm from each side. The thickness of the hot-rolled material after face cutting was 8 mm.

The hot-rolled material after the hot working step is subjected to a first cold working step [Step 5], in which the material is rolled along the length direction until the total working ratio reaches 62.5% (the thickness before working is 8 mm, and the thickness after working is 3 mm). Subsequently, the cold-rolled material after the first cold working step [Step 5] is subjected to a second heat treatment step [Step 6], in which the material is heat treated under specific 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 the material was rolled in the longitudinal direction at the total working rate listed in Table 2. Subsequently, the cold-rolled material after the second cold working step [Step 7] was subjected to a third heat treatment step [Step 8] in which the material was heat treated under the heat treatment conditions listed 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 the material was rolled in the longitudinal direction at the total working ratio listed in Table 2. Subsequently, the cold-rolled material after the third cold working step [Step 9] was subjected to a fourth heat treatment step [Step 10] in which the material was heat treated under the heat treatment conditions listed in Table 2.

In addition, for Examples 1 to 17 of the present invention 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 material was rolled in the longitudinal direction at the total working ratio described in Table 2. Subsequently, the cold-rolled material after the fourth cold working step [Step 11] was subjected to a fifth heat treatment step [Step 12] in which the material was heat treated under the heat treatment conditions described 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 undergoing the fourth cold working step [Step 11]. Furthermore, for Comparative Example 6, the time until the heating temperature is reached in the fifth heat treatment step [Step 12] is set to 600 seconds. In this manner, the copper alloy materials (copper alloy plates) of Examples 1 to 17 and Comparative Examples 1 to 6 of the present invention are produced.

Furthermore, in Table 1, a horizontal line "-" is written in the column for a component not contained in the alloy composition of the copper alloy raw material, clearly indicating that the component is not contained or, even if it is contained, the content of the component is less than the detection limit.

[Various Measurement and Evaluation Methods] The copper alloy materials (copper alloy plates) described in the present invention and comparative examples were used to conduct the following property evaluations. The evaluation conditions for each property were as follows.

[1] When the orientation distribution function (ODF) is expressed in terms of the Euler angle, the maximum value of the orientation density is determined when φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 is 15°, 20°, and 25°. For the copper alloy plates obtained in the present invention and the comparative example, a cross-section parallel to the rolling direction (extension direction) is mirror-polished to prepare a cross-sectional sample. EBSD measurement (measurement by electron backscattering diffraction) is then performed using a field emission scanning electron microscope (FE-SEM) to obtain crystal orientation analysis data using the SEM-EBSD method. In this case, the EBSD measurement is performed with an area of 0.2 mm ² and a step size of 0.5 μm. Based on the EBSD measurement results, the intensity calculation was performed using the data analysis software "OIM ANALYSIS" using the Harmonic Series Expansion, setting the Series Rank to 16 and the Gaussian Half-Width to 5°. The calculated results were then entered into the Enforce Orthotropic Sample Symmetry option was used to perform a cluster structure analysis. An ODF spectrum showing the intensity distribution of crystal orientations expressed in terms of Euler angles (φ1, Φ, φ2) was plotted. For conditions where φ2 was set to 15°, 20°, and 25°, a graph showing the orientation density in the ranges of φ1 = 0 to 90° and Φ = 0 to 90° was plotted with φ1 as the horizontal axis and Φ as the vertical axis. The maximum orientation density was determined for φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 = 15°, 20°, and 25°.

[2] Average grain size and standard deviation of copper alloy materials The average grain size and standard deviation of copper alloy materials were obtained from the grain size (diameter) graph obtained using the data analysis software "OIM ANALYSIS" using the crystal orientation analysis data of the SEM-EBSD method mentioned above. At this time, the average diameter and standard deviation obtained from the area fraction (area fraction) can be set 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 the scratches produced on copper alloy materials during stamping In order to evaluate the size of the scratches produced on the copper alloy materials during stamping, the shear test described in the shear test method for copper and copper alloy thin strips specified in the technical standard JCBA T310:2019 of the Japan Copper and Copper Alloy Association was carried out. Specifically, the mold was adjusted so that the gap between the upper mold (punch) and the lower mold (die) was within a range of 20 μm to 30 μm, and the ratio of the fracture surface to the shear surface was within a range of 30% to 50%. The copper alloy material was then punched into a square shape to produce a copper alloy material sample having a shear surface on the outer edge. The square had a dimension of 10 mm along the extension direction and another 10 mm along the sheet width direction, which intersects the extension direction at right angles.

FIG1 is a schematic diagram showing the copper alloy material of the present invention, viewed from above from a direction parallel to the cross-section, to facilitate identification of the outline of the cross-section (right edge) when the material is subjected to a stamping process. FIG1 schematically illustrates the outline of a cross-section 2 represented by a plane, which includes a direction X perpendicular to the cross-section 2 and a thickness direction Y. The copper alloy material 1 shown in FIG1 shows the cross-section 2 after being subjected to a stamping process. This stamping process is performed by lowering an upper die (punch) while the upper die (punch) is fixed to a lower die (punch) (not shown). Here, the cut surface 2 is formed with a collapsed angle 3, a shear surface 4, and a fracture surface 5, sequentially formed from the top surface 1a of the copper alloy material 1 after punching. The fracture surface 5 is formed in a chiseled shape relative to the shear surface 4, and a chisel 6 is often formed on the cut surface 2, which serves as the punching surface. Furthermore, a burr 7 is often formed at the lower edge of the cut surface 2, extending outward from the fracture surface 5.

In this embodiment, in order to make the outline 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 stamping visible, the sample material composed of the stamped copper alloy material 1 was observed using an optical microscope (manufactured by Olympus Corporation, model: GX71) at a magnification of 300 times from a direction parallel to the cut surface 2. Then, with respect to the scanning electron microscope (SEM) photograph, as shown in FIG. 1 , an imaginary line drawn parallel to the copper alloy material plate surface (along the direction X in FIG. 1 ) from the front end of the burr 7 and a boundary line 8 drawn at a position considered to be the boundary between the shear plane 4 and the fracture plane 5 are set as opposite sides. The vertices of the 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 ratio of the area of the copper alloy material 1 at that time to the area divided by the rectangle R is calculated as a percentage (%).

When the ratio of the area of the portion 9 where the copper alloy material 1 overlaps with the rectangle R relative to the calculated area of the rectangle R is 42% or more, the chisel 6 formed on the cut surface 2, which is the punching surface, is sufficiently small, and is evaluated as excellent. Furthermore, when the ratio of the area of the portion 9 where the copper alloy material 1 overlaps with the rectangle R relative to the area of the rectangle R is 30% or more and less than 42%, the chisel 6 on the punching surface is small, and is evaluated as good. On the other hand, when the ratio of the area of the portion 9 where the copper alloy material 1 overlaps with the rectangle R to the area of the rectangle R is less than 30%, the size of the chisel 6 on the punched surface is not within the appropriate range and is evaluated as "poor". The results are shown in Table 3.

[4] Determination of volume resistivity For the copper alloy material produced, the obtained plate with a thickness of 0.3 mm was cut into pieces with a width of 10 mm and a length of 300 mm to produce the test material.

Volume resistivity ρ is measured at room temperature (20°C) using the four-terminal method specified in Japanese Industrial Standards JIS C2525, with the voltage terminals set at a distance of 200 mm and a current of 100 mA. The volume resistivity ρ (μΩ·cm) is calculated from the voltage measured.

Regarding the measured volume resistivity ρ, a volume resistivity ρ of 80 μΩ·cm or more was considered sufficiently large and excellent as a resistor material, and was evaluated as "◎". Furthermore, a volume resistivity ρ of 70 μΩ·cm or more and less than 80 μΩ·cm was considered large and good as a resistor material, and was evaluated as "○". On the other hand, a volume resistivity ρ of less than 70 μΩ·cm was considered small and poor as a resistor material, and was evaluated as "×". In this embodiment, "◎" and "○" were evaluated as acceptable grades. The results are shown in Table 3.

[5] Method for measuring the electromotive force (EMF) of copper For the copper alloy material produced, the obtained plate with a thickness of 0.3 mm was cut into pieces with a width of 10 mm and a length of 1000 mm to produce the test material.

The measurement of the copper electromotive force (EMF) of the test materials is carried out in accordance with the Japanese Industrial Standard JIS C2527. More specifically, as shown in FIG2 , the copper thermoelectromotive force (EMF) of the test material 11 is measured by using a fully annealed pure copper wire with a diameter of 1 mm or less as the standard copper wire 21. The temperature measuring junction _P1, which connects the test material 11 to one end of the standard copper wire 21, is immersed in warm water maintained at 80°C in a constant temperature bath 41. Furthermore, the reference junctions _P21 and _P22, which connect the other ends of the test material 11 and the standard copper wire 21 to copper wires 31 and 32, respectively, are immersed in ice water at 0°C maintained in an ice point device 42. The electromotive force at this time is then measured using a voltage meter 43. The obtained electromotive force was divided by the temperature difference, 80°C, to determine the thermoelectric force (EMF) (μV/°C) on copper.

For the measured EMF against copper, an absolute value of 0.5 μV/°C or less was considered sufficiently low, indicating a good resistance material and was rated "◎." Furthermore, an absolute value greater than 0.5 μV/°C but less than 1.0 μV/°C was considered low, indicating a good resistance material and was rated "○." On the other hand, an absolute value greater than 1.0 μV/°C was considered high, indicating a poor resistance material and was rated "×." The results are shown in Table 3.

[6] Method for determining the temperature coefficient of resistance (TCR) For the copper alloy material produced, the obtained plate with a thickness of 0.3 mm was cut into pieces with a width of 10 mm and a length of 300 mm to produce the test material.

The temperature coefficient of resistance (TCR) is measured using the four-terminal method specified in Japanese Industrial Standards JIS C2525 and JIS C2526, with the voltage terminals set at 200 mm and the current at 100 mA. The voltage applied when the test material is heated to 150°C is measured, and the resistance value at 150°C (R _{150 °C} [μΩ]) is calculated from the obtained value. The voltage applied when the test material is cooled to 20°C is then measured, and the resistance value at 20°C (R _{20 °C} [μΩ]) is calculated from this value. Based on the obtained values of R _{150 ℃} and R _{20 ℃} , the temperature coefficient of resistance (ppm/℃) was calculated using the formula TCR = {(R _{150 ℃} [μΩ] - R _{20 ℃} [μΩ]) / R _{20 ℃} [μΩ]} × {1/(150[℃] - 20[℃])} × 10 ⁶ .

For the measured temperature coefficient of resistance (TCR), an absolute value of less than 50 ppm/°C was considered sufficiently low, indicating that the resistor material was excellent and was rated "◎." Furthermore, an absolute value of 50 ppm/°C or higher and 60 ppm/°C or lower was considered low, indicating that the resistor material was good and was rated "○." On the other hand, an absolute value greater than 60 ppm/°C was considered high, indicating that the resistor material was poor and was rated "×." The results are shown in Table 3.

[7] Evaluation of reliability Furthermore, in order to investigate the reliability of copper alloy materials used as resistor materials for a long time, especially the stability of electrical properties under heat, etc., for Examples 1 to 17 of the present invention and Comparative Examples 1 to 6, the test materials whose volume resistivity was measured in the above-mentioned measurement of volume resistivity [4] were heated at 400°C for 2 hours to conduct an accelerated test for the stability of electrical properties under heat. After the accelerated heating test, the volume resistivity of the test materials was measured using the same method as the above-mentioned measurement of volume resistivity [4], and the difference in volume resistivity was calculated by subtracting the volume resistivity after heating from the volume resistivity before heating. Here, if the difference in volume resistivity (the volume resistivity before heating minus the volume resistivity after heating) is 1.0 μΩ·cm or less, the decrease in volume resistivity due to heating is considered small, indicating excellent reliability, and is evaluated as "◎". Furthermore, if the difference in volume resistivity (the volume resistivity before heating minus the volume resistivity after heating) exceeds 1.0 μΩ·cm, the decrease in volume resistivity due to heating is considered large, and from a reliability perspective, it is relatively unsatisfactory, and is evaluated as "○". The results are shown in Table 3.

[8] Comprehensive evaluation Among the evaluation results, the evaluation results of the size of the scratches generated on the copper alloy material during stamping, the volume resistivity ρ, the thermoelectrodynamic force (EMF) of copper, and the temperature coefficient of resistance (TCR) are evaluated as "◎". If all four characteristics are evaluated as "◎", it is considered that the four characteristics of the size of the scratches generated on the copper alloy material during stamping, the volume resistivity ρ, the thermoelectrodynamic force (EMF) of copper, and the temperature coefficient of resistance (TCR) are excellent and are evaluated as "◎". In addition, if at least one of the four evaluation results is evaluated as "○" and the rest are evaluated as "◎", it is considered that the four characteristics are at least good and are evaluated as "○". On the other hand, if at least one of the evaluation results for stamping workability, volume resistivity ρ, thermoelectromotive force (EMF) relative to copper, and temperature coefficient of resistance (TCR) was rated "×," it was considered that at least one of these four characteristics was unacceptable and was rated "×." The results are shown in Table 3.

[Table 1]

[Table 2]

[Table 3]

Based on the results in Tables 1 to 3, the copper alloy materials of Examples 1 to 17 of the present invention have alloy compositions and maximum orientation densities within the appropriate ranges of the present invention. Furthermore, the ratios of the area of the portion 9 where the copper alloy material 1 overlaps with the rectangle R relative to the area of the rectangle R were all rated "◎" or "○," indicating that the gouges formed on the punched surface were small. Furthermore, the copper alloy materials of Examples 1 to 17 of the present invention were all rated "◎" or "○" for volume resistivity ρ, thermoelectromotive force (EMF) relative to copper, and temperature coefficient of resistance (TCR).

On the other hand, when the orientation distribution function (ODF) of the copper alloy materials of Comparative Examples 1 and 2 is expressed in terms of the Euler angle, the maximum values of the orientation density are large when φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 = 15°, 20°, and 25°, which are outside the appropriate range of the present invention. Therefore, the copper alloy materials of Comparative Examples 1 and 2 were rated "Poor" for the size of the gouges produced in the copper alloy materials during stamping.

Furthermore, the copper alloy material of Comparative Example 3 has a low Ni content and an alloy composition outside the appropriate range of the present invention. Therefore, the copper alloy material of Comparative Example 3 was evaluated as "×" in terms of copper thermoelectric force (EMF).

Furthermore, the copper alloy material of Comparative Example 4 has low Mn and Ni contents, resulting in an alloy composition outside the appropriate range of the present invention. Therefore, the copper alloy material of Comparative Example 4 was rated "Poor" for volume resistivity ρ. In particular, the copper alloy material of Comparative Example 4 was rated "Poor" for volume resistivity ρ due to its low Mn content.

Furthermore, the copper alloy material of Comparative Example 5 has a high Mn content and the alloy composition is outside the appropriate range of the present invention. Therefore, the copper alloy material of Comparative Example 5 was evaluated as "×" in terms of copper thermoelectric force (EMF).

Furthermore, the copper alloy material of Comparative Example 6 has a high Ni content and the alloy composition is outside the appropriate range of the present invention. Therefore, the copper alloy material of Comparative Example 6 was evaluated as "×" in terms of copper thermoelectromotive force (EMF) and temperature coefficient of resistance (TCR).

Based on these results, it was confirmed that the copper alloy material of the present invention exhibits minimal chipping during stamping when the alloy composition and the maximum orientation density (ODF) expressed as the Euler angles (φ1, φ, φ2) are within the appropriate ranges of the present invention. Furthermore, it was confirmed that the copper alloy material of the present invention exhibits at least good performance in terms of volume resistivity ρ, thermoelectromotive force (EMF) relative to copper, and temperature coefficient of resistance (TCR).

In addition, Figure 3 is the following graph, which represents the orientation distribution function (ODF) of the copper alloy material of Example 14 of the present invention using the Euler angle (φ1, Φ, φ2) and sets φ1 as the horizontal axis and Φ as the vertical axis. It represents the orientation density at φ1 = 0 to 90° and Φ = 0 to 90° at this time. Figure 3 (a) is a graph when φ2 = 15°, Figure 3 (b) is a graph when φ2 = 20°, and Figure 3 (c) is a graph when φ2 = 25°. Based on this graph, it can be seen that the maximum orientation density of the copper alloy material of Example 14 of the present invention when φ1 = 0 to 90°, Φ = 0 to 90°, and φ2 is 15°, 20°, and 25° is 3.1 (the value after rounding off to the second decimal place is set as the measured value of the maximum orientation density).

FIG4 shows a scanning electron microscope (SEM) photograph of the copper alloy material of the present invention and comparative examples, taken from a direction parallel to the cross-section to facilitate identification of the cross-sectional profile (right edge) of the copper alloy material subjected to punching. FIG4(a) is an SEM photograph of the cross-sectional profile of the copper alloy material of Example 5 of the present invention, and FIG4(b) is an SEM photograph of the cross-sectional profile of the copper alloy material of Comparative Example 1. The SEM images show that the copper alloy material of the present invention has smaller scratches on the fracture surface during stamping than the copper alloy material of the comparative example.

Furthermore, it can be seen that, compared to Examples 5, 8, and 12 of the present invention, which had an Fe content of 0.30 mass% or more and were rated "○" in the reliability evaluation results, Examples 1 to 4, 6, 7, 9 to 11, and 13 to 17 of the present invention had improved stability of electrical characteristics under heat by setting the Fe content to 0.20 mass% or less, and thus were rated "◎" in the reliability evaluation results.

Furthermore, it can be seen that compared to Examples 1 to 3 of the present invention, whose evaluation results of the temperature coefficient of resistance (TCR) were evaluated as "○", Examples 4 to 17 of the present invention have smaller absolute values of the temperature coefficient of resistance (TCR) by containing one or both of Fe and Co, and therefore were evaluated as "◎" in the evaluation results of the temperature coefficient of resistance (TCR).

1: Copper alloy material 1a: Top surface of copper alloy material 1b: Bottom surface of copper alloy material 2: Cut surface 3: Collapse 4: Shear surface 5: Fracture surface 6: Chisel on punched surface 7: Burr 8: Boundary line 9: Overlapping portion of rectangle and copper alloy material 11: Test material 21: Standard copper wire 31, 32: Copper wire 41: Constant temperature bath 42: Freezing point device ₄₃ : Voltage meter P1: Temperature measurement junction _P21 , _P22 : Reference junction R: Rectangle X: Perpendicular to cut surface Y: Thickness direction

Figure 1 is a schematic diagram showing a copper alloy material subjected to stamping, viewed from above from a direction parallel to the cut surface, to facilitate identification of the outline of the cut surface (right edge) of the copper alloy material subjected to stamping. Figure 2 is a schematic diagram illustrating the method for determining the thermoelectromotive force (EMF) of copper for each sample material of the present invention and comparative examples. Figure 3 is a graph showing the 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. The graph shows the orientation density in the ranges of φ1 = 0 to 90° and Φ = 0 to 90°. Figure 3(a) shows the graph when φ2 = 15°, Figure 3(b) shows the graph when φ2 = 20°, and Figure 3(c) shows the graph when φ2 = 25°. Figure 4 shows scanning electron microscope (SEM) photographs of the copper alloy materials of the present invention and comparative examples, taken from a direction parallel to the cross-section to facilitate identification of the outline of the cross-section (right edge) of the copper alloy materials subjected to the punching process. Figure 4(a) shows the copper alloy material of Example 5 of the present invention, and Figure 4(b) shows the copper alloy material of Comparative Example 1.

Domestic Storage Information (Please enter in order by institution, date, and number) None International Storage Information (Please enter in order by country, institution, date, and number) None

1: Copper alloy material

1a: Top surface of copper alloy material

1b: Bottom surface of copper alloy material

2: Cross-section

3: Corner collapse

4: Shear plane

5: Fracture surface

6: Chisel damage on punching surface

7: Rough Edges

8: Boundary Line

9: The overlapping portion of the rectangle and the copper alloy material

R: Rectangle

X: Direction perpendicular to the cross section

Y: thickness direction

Claims (6)

A copper alloy material having the following alloy composition: Contains 20.0 mass% to 35.0 mass% Mn and 6.5 mass% to 17.0 mass% Ni, The remainder consisting of Cu and unavoidable impurities. In a longitudinal cross-section of the copper alloy material, including the extension direction and the thickness direction, when the orientation distribution function (ODF) obtained by crystal orientation analysis using SEM-EBSD is expressed as Euler angles (φ1, φ, φ2), the maximum orientation density is 6.0 or less when φ1 = 0 to 90°, φ = 0 to 90°, and φ2 = 15°, 20°, and 25°. The copper alloy material as described in claim 1, wherein, in the aforementioned longitudinal cross-section, the average grain size of the grains obtained from the crystal orientation analysis data using the SEM-EBSD method is less than 20 μm and the standard deviation of the aforementioned average grain size is less than 10 μm. The copper alloy material as described in claim 1, wherein the alloy composition further contains one or both of 0.01 mass% to 0.50 mass% of Fe and 0.01 mass% to 2.00 mass% of Co. The copper alloy material as described in claim 1, wherein the alloy composition further contains at least one selected from the group consisting of: 0.01 mass% to 5.00 mass% Sn, 0.01 mass% to 5.00 mass% Zn, 0.01 mass% to 0.50 mass% Cr, 0.01 mass% to 0.50 mass% Ag, 0.01 mass% to 1.00 mass% Al, 0.01 mass% to 0.50 mass% Mg, 0.01 mass% to 0.50 mass% Si, and 0.01 mass% to 0.50 mass% P. A resistor material for a resistor, comprising the copper alloy material described in any one of claims 1 to 4. A resistor, which is a shunt resistor or a chip resistor, has the resistor material for the resistor described in claim 5.