TWI851025B - Copper alloy material, resistor material for resistor using the copper alloy material, 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, wherein the copper alloy material has excellent stamping workability, a sufficiently high volume resistivity, and a small absolute value of copper thermoelectromotive force (EMF). The copper alloy material has 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, and containing 0 mass ppm or more and 800 mass ppm or less of O and 0 mass ppm or more and 800 mass ppm or less of C, and the total content of O and C is 60 mass ppm or more and 800 mass ppm or less, and the remainder includes Cu and unavoidable impurities.

Description

Copper alloy material, resistor material for resistor using the copper alloy material, 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.

Metal materials used for resistor materials are required to have stable resistance values even when the ambient temperature changes. In response to this requirement, Cu-Mn-Ni alloys and Cu-Mn-Sn alloys are widely used as alloy materials constituting resistor materials because their resistance values are unlikely to change even when the ambient temperature changes.

However, when these Cu-Mn-Ni alloys and Cu-Mn-Sn alloys are used as resistor materials in a resistor designed to have a predetermined resistance value by forming a circuit (pattern) using the resistor material, the volume resistivity is as small as less than ⁵⁰ × ^10-8 (Ω・m), so it is necessary to reduce the cross-sectional area of the resistor material to increase the resistance value of the resistor. In such a resistor, there is the following disadvantage: when a large current flows temporarily in the circuit or when a relatively large current flows continuously to a certain extent, the Joule heat generated in the resistor material with a small cross-sectional area becomes high and heat is generated, and as a result, the resistor material becomes easy to break (melt) due to heat.

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

For example, Patent Document 1 states that, in a copper alloy containing Mn in a range of 23 mass % to 28 mass % and Ni in a range of 9 mass % to 13 mass %, the mass fraction of Mn and the mass fraction of Ni are configured so that the thermoelectric dynamic force of copper at 20°C is less than ±1 μV/°C, thereby obtaining a copper alloy that can obtain a relatively high resistance (volume resistivity ρ) of ⁵⁰ × ^10-8 [Ω·m] or more, has a relatively small thermoelectric dynamic force of copper (thermoelectric dynamic force of copper, EMF), has a relatively low temperature coefficient of resistance, and has a relatively high stability of the inherent resistance with respect to time (time invariance).

Furthermore, Patent Document 2 states that, by setting the value x [ppm/°C] of the temperature coefficient of resistance (TCR) in the temperature range of 20°C to 60°C to within the range of -10≦x≦-2 or 2≦x≦10 in a copper alloy containing Mn in the range of 21.0 mass % to 30.2 mass % and Ni in the range of 8.2 mass % to 11.0 mass %, and setting the volume resistivity ρ to 80× ^10-8 [Ω・m] to ¹¹⁵ × ^10-8 [Ω・m], it is possible to suppress the cross-sectional area of a circuit of a resistor such as a chip resistor using a resistor material from being reduced, and at the same ^time suppress the Joule heat of the resistor material from being increased. [Prior Art Document] (Patent Document)

Patent document 1: Japanese Patent Publication No. 2016-528376 Patent document 2: Japanese Patent Publication No. 2017-053015

[The problem the invention is trying to solve]

With the miniaturization and high integration of electrical and electronic parts in recent years, resistors or resistor materials used in resistors have also been gradually miniaturized. Resistor materials used in resistors are generally formed by cutting processes such as stamping. Therefore, in order to reduce the deviation of resistance value, copper alloy materials are required to have excellent stamping processability. Here, in order to give copper alloy materials excellent stamping processability, it is necessary to improve the dimensional accuracy of the cut surface when performing stamping.

Furthermore, in recent years, in the electrical systems of electric vehicles, etc., resistors such as shunt resistors and chip resistors are being sought for high-precision resistors that have a large volume resistivity ρ and can withstand a higher temperature environment, and copper alloys used in such resistors are also being sought for high-precision copper alloys that can withstand a higher temperature environment. More specifically, a copper alloy material is being sought that has a large volume resistivity ρ, is not easy to generate electromotive force with copper even at high temperatures, and has a small absolute value of thermoelectric electromotive force (EMF) to copper.

Therefore, the object of the present invention is to provide a copper alloy material, a resistor material for a resistor using the copper alloy material, and a resistor, wherein the copper alloy material has excellent stamping workability, a sufficiently high volume resistivity, and a small absolute value of copper thermoelectromotive force (EMF). [Technical means for solving the problem]

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, and containing 0 mass ppm or more and 800 mass ppm or less of O and 0 mass ppm or more and 800 mass ppm or less of C, wherein the total content of O and C is 60 mass ppm or more and 800 mass ppm or more. 0 mass ppm or less, the remainder comprising Cu and unavoidable impurities; by utilizing the 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 at the same time, the absolute value of the copper thermoelectromotive force (EMF) in the temperature range from room temperature (e.g., 5°C to 35°C) to high temperature (e.g., 80°C) is also small, and the stamping processability is excellent, thereby completing the present invention.

In order to achieve the above-mentioned object, the gist of the present invention is 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, and simultaneously containing 0 mass ppm or more and 800 mass ppm or less of O and 0 mass ppm or more and 800 mass ppm or less of C, wherein the total amount of O and C is 60 mass ppm or more and 800 mass ppm or less, and the remainder comprises Cu and unavoidable impurities. (2) A copper alloy material as described in (1) above, wherein, in observing a cross section of the copper alloy material perpendicular to the extension direction during processing, among the precipitated particles containing at least one of oxides and carbides observed within a field of view of ¹⁰⁰⁰⁰ μm2, the number of precipitated particles having a maximum size exceeding 20 μm, i.e., coarse precipitated particles, is 3 or less. (3) A copper alloy material as described in (1) or (2) above, wherein the alloy composition further contains at least one component selected from the group consisting of: 0.01 mass% to 0.50 mass% Fe, 0.01 mass% to 2.00 mass% Co, 0.01 mass% to 5.00 mass% Sn, 0.01 mass% to 5.00 mass% and more. % and less than 0.50 mass % of Zn, 0.01 mass % and less than 0.50 mass % and less than 0.50 mass % and less than 0.01 mass % and less than 1.00 mass % and less than 0.01 mass % and less than 0.50 ...

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 excellent stamping workability, a sufficiently high volume resistivity, and a small absolute value of copper thermoelectromotive force (EMF).

The preferred embodiment of the copper alloy material of the present invention is described in detail below. In addition, in the composition of the alloy of the present invention, "mass %" may be simply expressed as "%". Also, "mass ppm" may be simply expressed as "ppm".

The copper alloy material according to the present invention has 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, and containing 0 mass ppm or more and 800 mass ppm or less of O and 0 mass ppm or more and 800 mass ppm or less of C, wherein the total amount of O and C is 60 mass ppm or more and 800 mass ppm or less, and the remainder includes Cu and unavoidable impurities.

In the copper alloy material of the present invention, Mn is contained in a range of 20.0 mass % to 35.0 mass % and Ni is contained in a range of 6.5 mass % to 17.0 mass %, thereby increasing the volume resistivity ρ and reducing the absolute value of the thermoelectromotive force (EMF, hereinafter sometimes simply referred to as "thermoelectromotive force") to copper generated between a temperature environment of 0°C and 80°C. Therefore, even in a high temperature environment, the high performance of the resistor can be improved.

In this regard, the copper alloy described in the above-mentioned patent documents 1 and 2 is a single phase with a face-centered cubic structure that is rich in ductility. Therefore, there is a problem that the dimensional accuracy of the cut surface during the punching process is low, and the resistance value of the resistor obtained from the copper alloy varies.

However, in the copper alloy material according to the present invention, Mn is contained in a range of 20.0 mass % or more and 35.0 mass % or less, and O and C are contained in a total of 60 mass ppm or more, so that one or both of O and C are bonded with Mn to form oxides or carbides, thereby increasing the proportion of shear planes in the cross section when the copper alloy material is subjected to stamping. The larger the proportion of this shear plane, the smaller the area of the collapsed angle and the fracture surface in the cross section becomes, so that the flatness of the cut surface can be improved, and the processing accuracy of the stamping process can be improved. As a result, the resistor obtained from the copper alloy can be made with high precision.

Furthermore, in the copper alloy material according to the present invention, Mn is contained in the range of 20.0 mass % to 35.0 mass %, Ni is contained in the range of 6.5 mass % to 17.0 mass %, and O and C are contained in the range of 800 mass ppm or less in total, so that embrittlement of the copper alloy material is not likely to occur, thereby achieving high strength of the copper alloy material and making it easy to manufacture.

As a result, by utilizing the copper alloy material according to the present invention, it is possible to provide a copper alloy material, a resistor material for a resistor using the copper alloy material, and a resistor, wherein the copper alloy material has excellent stamping workability, a sufficiently high volume resistivity ρ, and a small absolute value of copper thermoelectromotive force (EMF).

[1] Composition of copper alloy material ＜Essential components＞ 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 essential components.

(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. Therefore, the Mn content is preferably set within the range of 20.0 mass % or more and 35.0 mass % or less.

(Ni: 6.5 mass% or more and 17.0 mass% or less) Ni (nickel) is an element that can adjust the thermoelectric force (EMF) to copper in the positive direction. In order to play this role, it is better to contain 6.5 mass% or more of Ni. On the other hand, if the Ni content exceeds 17.0 mass%, it becomes difficult to obtain a uniform structure, and the volume resistivity ρ and the thermoelectric force (EMF) to copper may change. In particular, from the perspective of obtaining a copper alloy material having desired characteristics or from the perspective of obtaining a copper alloy material that is easy to manufacture, the Ni content is set within the range of 6.5 mass % or more and 17.0 mass % or less, preferably within the range of 6.5 mass % or more and 12.0 mass % or less, and more preferably within the range of 6.5 mass % or more and 9.0 mass % or less.

(One or two of O and C: a total of 60 mass ppm or more and 800 mass ppm or less) O (oxygen) and C (carbon) have the following effects: by forming oxides or carbides with Mn, the proportion of shear planes in the cross section of the copper alloy material during stamping is increased, thereby improving the stamping workability; therefore, at least one of these elements is required. In order to exert this effect, O and C preferably contain a total of 60 mass ppm or more, and more preferably a total of 100 mass ppm or more. On the other hand, if the total amount of one or two of O and C exceeds 800 mass ppm, the copper alloy material will become brittle and difficult to manufacture. Therefore, from the perspective of seeking high strength and improving stamping workability, the content of one or both of O and C is set within a range of 60 mass ppm or more and 800 mass ppm or less, and more preferably, within a range of 100 mass ppm or more and 800 mass ppm or less. In addition, the content of one or both of O and C may also be set within a range of 60 mass ppm or more and 600 mass ppm or less, or within a range of 100 mass ppm or more and 600 mass ppm or less.

(O and C: 0 mass ppm or more and 800 mass ppm or less, respectively) Here, from the perspective of seeking high strength without embrittlement of the copper alloy material, the O content is set in the range of 0 mass ppm or more and 800 mass ppm or less. From the same perspective, the C content is also set in the range of 0 mass ppm or more and 800 mass ppm or less. One or both of the O content and the C content may also be set in the range of 0 mass ppm or more and 600 mass ppm or less.

＜Optional added ingredients＞ The copper alloy material of the present invention can further contain at least one component selected from the group consisting of 0.01 mass% to 0.50 mass% Fe, 0.01 mass% to 2.00 mass% Co, 0.01 mass% to 3.00 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.

(Fe: 0.01 mass% or more and 0.50 mass% or less) Fe (iron) is an element that can adjust the thermoelectric motive force (EMF) of copper toward a positive value. In order to exert this effect, it is better to contain 0.01 mass% or more of Fe. On the other hand, if the Fe content exceeds 0.50 mass%, it becomes difficult to obtain a uniform structure, and the electrical performance is prone to deviation. Therefore, the Fe content is preferably set in the range of 0.01 mass% or more and 0.50 mass% or less.

(Co: 0.01 mass% or more and 2.00 mass% or less) Co (cobalt) is an element that can adjust the thermoelectric motive force (EMF) of copper toward a positive value. In order to exert this effect, it is better to contain 0.01 mass% or more of Co. On the other hand, if the Co content exceeds 2.00 mass%, it becomes difficult to obtain a uniform structure, and the electrical performance is prone to deviation. Therefore, the Co content is preferably set in the range of 0.01 mass% or more and 2.00 mass% or less.

(Sn: 0.01 mass% or more and 5.00 mass% or less) Sn (tin) is a component that can be used to adjust the volume resistivity ρ. In order to play this role, it is better to contain 0.01 mass% or more of Sn. On the other hand, the Sn content is set to 5.00 mass% or less, so that the situation in which the manufacturability is reduced due to the embrittlement of the copper alloy material is not likely to occur.

(Zn: 0.01 mass% or more and 5.00 mass% or less) Zn (zinc) is a component that can be used to adjust the volume resistivity ρ. In order to play this role, it is better to contain 0.01 mass% or more of Zn. On the other hand, since it may have an adverse effect on the volume resistivity ρ and the stability of the electrical properties of the resistor such as copper thermoelectromotive force (EMF), the Zn content is preferably set to 5.00 mass% or less.

(Cr: 0.01 mass% or more and 0.50 mass% or less) Cr (chromium) is a component that can be used to adjust the volume resistivity ρ. In order to play this role, it is better to contain 0.01 mass% or more of Cr. On the other hand, since it may have an adverse effect on the volume resistivity ρ and the stability of the electrical properties of the resistor such as copper thermoelectromotive force (EMF), the Cr content is preferably set to 0.50 mass% or less.

(Ag: 0.01 mass% or more and 0.50 mass% or less) Ag (silver) is a component that can be used to adjust the volume resistivity ρ. In order to play this role, it is better to contain 0.01 mass% or more of Ag. On the other hand, since it may have an adverse effect on the volume resistivity ρ and the stability of the electrical properties of the resistor such as copper thermoelectromotive force (EMF), the Ag content is preferably set to 0.50 mass% or less.

(Al: 0.01 mass% or more and 1.00 mass% or less) Al (aluminum) is a component that can be used to adjust the volume resistivity ρ. In order to play this role, it is better to contain 0.01 mass% or more of Al. On the other hand, since it may make the copper alloy material embrittled, the Al content is preferably set to 1.00 mass% or less.

(Mg: 0.01 mass% or more and 0.50 mass% or less) Mg (magnesium) is a component that can be used to adjust the volume resistivity ρ. In order to play this role, it is better to contain 0.01 mass% or more of Mg. On the other hand, since it may make the copper alloy material embrittled, the Mg content is preferably set to 0.50 mass% or less.

(Si: 0.01 mass% or more and 0.50 mass% or less) Si (silicon) is a component that can be used to adjust the volume resistivity ρ. In order to play this role, it is better to contain 0.01 mass% or more of Si. On the other hand, since it may make the copper alloy material embrittled, the Si content is preferably set to 0.50 mass% or less.

(P: 0.01 mass% or more and 0.50 mass% or less) P (phosphorus) is a component that can be used to adjust the volume resistivity ρ. In order to play this role, it is better to contain 0.01 mass% or more of P. On the other hand, since it may make the copper alloy material embrittled, the P content is preferably set to 0.50 mass% or less.

(Total amount of optional additives: 0.01 mass% or more and 5.00 mass% or less) In order to obtain the effects obtained by the above-mentioned optional additives, at least one (optional additive) component selected from the group consisting of Fe, Co, Sn, Zn, Cr, Ag, Al, Mg, Si and P is preferably contained in a total amount of 0.01 mass% or more. On the other hand, if the content of these optional additives is included in large amounts, the electrical properties become unstable and it is difficult to manufacture copper alloy materials, so it is preferably set to a total of 5.00 mass% or less.

<Remainder: Cu and unavoidable impurities> In addition to the above-mentioned essential components and optional additives, the remainder is composed of Cu (copper) and unavoidable impurities. In addition, the so-called "unavoidable impurities" referred to here refer to a type of impurity that is generally present in the raw materials of copper-based products, or is inevitably mixed in the manufacturing process and is originally unnecessary, but is allowed because it is a trace amount and does not adversely affect the characteristics of copper-based products. Components that can be listed as unavoidable impurities include, for example: non-metallic elements such as sulfur (S); and metal elements such as antimony (Sb). Furthermore, the upper limit of the content of these components can be set as: 0.05 mass % for each of the above components, and 0.10 mass % for the total amount of the above components.

[2] Shape and metal structure of copper alloy material The shape of the copper alloy material of the present invention is not particularly limited. From the perspective of facilitating the following hot or cold stretching process or cutting process such as punching, a plate is preferred. Here, in a copper alloy material formed by rolling such as a plate, the rolling direction can be set as the stretching direction. On the other hand, in addition to a plate or a rod, the copper alloy material of the present invention can also be in the form of a strip such as a strip, or a wire such as a rectangular wire and a round wire. By forming the copper alloy material of the present invention into these shapes, it is possible to facilitate cutting of the ends. In particular, in copper alloy materials of these shapes formed by wire drawing, stretching, or extrusion, any one of the wire drawing direction, stretching direction, and extrusion direction can be set as the extension direction.

Here, the copper alloy material is preferably: in the cross-section observation orthogonal to the extension direction (wire drawing direction, extension direction, extrusion direction) during processing, among the precipitated particles containing at least one of oxides and carbides observed within a field of view of ^10000μm2 , the number of precipitated particles with a maximum size exceeding 20μm, i.e., coarse precipitated particles, is 3 or less. Thereby, the oxide or carbide of manganese is more evenly dispersed in the copper alloy material, thereby being able to further increase the proportion of the shear plane in the cross-section of the copper alloy material subjected to stamping, thereby being able to improve the stamping workability, and being able to further improve the dimensional accuracy of the copper alloy material after stamping. In particular, precipitated particles with a maximum size exceeding 20 μm tend to form a region with sparse oxides or carbides around the particles, which tends to make the cross-section during stamping uneven, so the amount contained in the copper alloy material is preferably small. Therefore, from the perspective of making the cross-section during stamping uniform to improve the processing accuracy of stamping, the number of coarse precipitated particles observed within a viewing area of 10,000 μm ² is preferably 3 or less, more preferably 1 or less, and most preferably 0.

The determination of the number of coarse precipitated particles containing oxides or carbides in this specification can be carried out in the following manner: after preparing a test material by embedding the material in a resin in such a way that a cross section of a copper alloy material perpendicular to the extension direction during processing is exposed, the cross section perpendicular to the extension direction is ground, and then an optical microscope is used to observe the exposed crystals with a 100 μm×100 μm square as a field of view, thereby measuring the particle size of the precipitated particles containing oxides or carbides represented by black in the microscope image.

[3] An example of a method for producing a copper alloy material The copper alloy material can be produced by controlling the alloy composition and the process in combination, and the process is not particularly limited. An example of a process for producing the copper alloy material can be the following method.

An example of a method for producing a copper alloy material of the present invention is to sequentially perform at least the following steps on a copper alloy material having an alloy composition substantially the same as the alloy composition of the above-mentioned copper-based material: a casting step [step 1], a homogenization heat treatment step [step 2], a hot working step [step 3], a first cold working step [step 4], and a first annealing step [step 5].

(i) Casting step [step 1] The casting step [step 1] is to use a high-frequency melting furnace to melt the copper-based material having the above alloy composition in an inert gas atmosphere as a non-oxidizing atmosphere or in a vacuum to cast a casting block (ingot) of a specified shape (for example, 30 mm thick, 50 mm wide, and 300 mm long). In addition, the alloy composition of the copper-based material may not be completely consistent with the alloy composition of the copper alloy material being manufactured due to the addition of components in each step of the manufacturing process, but it has an alloy composition that is substantially the same as the alloy composition of the copper alloy material.

Here, the casting step [step 1] is to melt and cast a copper-based material of copper, manganese, nickel, graphite and copper oxide, or a copper-based material containing copper, manganese, nickel, graphite, copper oxide, and at least one of the above-mentioned optional additives. Here, manganese has the characteristic of easily forming oxides and carbides, so by reacting with carbon constituting graphite or oxygen contained in copper oxide, precipitation particles containing oxides or carbides with fewer coarse precipitation particles can be obtained. Therefore, the copper alloy material obtained by the above-mentioned manufacturing method can contain oxides or carbides within the range of the above-mentioned alloy composition, so that the obtained copper alloy material can be strengthened and the punching workability can be improved.

The casting step [step 1] is preferably: after the molten metal of the copper-based material is kept at a melting temperature in the range of 1100°C to 1250°C for a holding time of less than 2 hours, it is cooled to 600°C or less at an average cooling rate of 0.5°C or more per second to obtain a casting. Thereby, fine oxides or carbides can be dispersed in the casting with high uniformity. On the other hand, when the melting temperature is increased and when the holding time at the melting temperature is prolonged, or when the cooling rate during casting is slow, coarse oxides or carbides may increase. Therefore, from the viewpoint of improving the stamping workability by reducing the precipitation of coarse oxides or carbides and dispersing the oxides or carbides with higher uniformity, the melting temperature in the casting step [step 1], or the holding time at the melting temperature, and the cooling rate during casting are preferably within the above range. In particular, the holding time at the melting temperature is more preferably within 1 hour.

(ii) Homogenization heat treatment step [step 2] The homogenization heat treatment step [step 2] is a step of performing heat treatment for homogenization on the casting after the casting step [step 1]. Here, from the viewpoint of suppressing grain coarsening, the heat treatment conditions in the homogenization heat treatment step [step 2] are preferably: the heating temperature is set within the range of 750°C or more and 900°C or less, and the holding time at the heating temperature is set within the range of 10 minutes or more and 10 hours or less.

(iii) Hot working step [step 3] The hot working step [step 3] is a step of producing a hot worked material by applying heat to the homogenized casting until it reaches a specified thickness and size by performing stretching processes such as rolling and wire drawing. Here, the hot working step [step 3] includes both a hot rolling step and a hot stretching (wire drawing) step. The conditions of the hot working step [step 3] are preferably: the processing temperature is within the range of 750°C or more and 900°C or less, which can be the same as the heating temperature in the homogenization step [step 2]. In addition, the processing rate in the hot working step [step 3] is preferably 10% or more.

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

The hot-worked material after the hot-working step [step 3] is preferably cooled. Here, the means for cooling the hot-worked material is not particularly limited. For example, from the perspective of making it difficult for grain coarsening to occur, it is preferred to increase the cooling rate as much as possible. It is preferred to set the cooling rate to more than 10°C/second by means such as water cooling.

Here, the hot-working material after cooling can be subjected to plane cutting to remove the surface plane. By performing plane cutting, the oxide film and defects on the surface generated in the hot working step [step 3] can be removed. The conditions for plane cutting are not particularly limited as long as they are the conditions usually performed. The amount of the surface plane removed from the hot-working material by plane cutting can be appropriately adjusted according to the conditions of the hot working step [step 3], and can be set to, for example, about 0.5 to 4 mm from the surface plane of the hot working material.

(v) First cold working step [step 4] The cold working step [step 4] is a step of cold-working the hot-worked material after the hot working step [step 3] to perform stretching processing such as rolling and wire drawing at an arbitrary processing rate in accordance with the thickness or size of the product. Here, the first cold working step [step 4] includes both the cold rolling step and the cold stretching (wire drawing) step. The conditions of the stretching processing such as rolling and wire drawing in the first cold working step [step 4] can be set in accordance with the size of the hot-worked material. In particular, in the first annealing step [step 5] described below, from the viewpoint of promoting uniform precipitation of grains by recrystallization, it is preferred that the total processing rate in the first cold working step [step 4] be set to 50% or more.

(vi) First annealing step [step 5] The first annealing step [step 5] is a step of annealing for recrystallizing the cold rolled material after the first cold working step [step 4]. Here, in the first annealing step [step 5], the heat treatment conditions are: the heating temperature is in the range of 600°C to 800°C, and the holding time at the heating temperature is in the range of 1 minute to 2 hours. On the other hand, when the heating temperature is less than 600°C and when the holding time is less than 1 minute, it is difficult to recrystallize the copper alloy material. In addition, when the heating temperature exceeds 800°C and when the holding time exceeds 2 hours, the grains may coarsen, thereby reducing the workability.

Here, it is preferred to repeat the cold working step and annealing step more than once for the cold rolled material after the first annealing step [step 5]. For example, the cold working step and annealing step may be performed for the cold rolled material after the first annealing step [step 5], and the cold working step and annealing step at this time may be set as the second cold working step [step 6] and the second annealing step [step 7], respectively. In this way, by repeating the cold working step and the annealing step more than once, the copper alloy material becomes a plate or rod, bar, or wire having a desired shape, and coarse grains are not easily formed, so that a copper alloy material showing desired characteristics in terms of processability, volume resistivity, and thermoelectric potential of copper can be obtained.

At this time, the total processing rate in the second cold working step [step 6] can be set to 50% or more. In addition, the conditions of the heat treatment in the second annealing step [step 7] are: the heating temperature is within the range of 600°C to 800°C, and the holding time at the heating temperature is within the range of 1 minute to 2 hours.

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

The above describes the implementation form of the present invention, but the present invention is not limited to the above implementation form, including the concept of the present invention and various aspects included in the scope of the patent application, and various changes can be made within the scope of the present invention. [Example]

Next, in order to make the effects of the present invention more clear, 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) Copper, manganese, nickel, graphite, copper oxide and any additional components as copper-based materials are mixed in the proportion of the alloy composition shown in Table 1, and the following casting step [Step 1] is performed to obtain a casting: melted in a non-oxidizing atmosphere using a high-frequency melting furnace, and then cooled from the molten metal to 600°C for casting. Here, the optional additional components with a horizontal line "-" among the components listed in Table 1 are not added to the copper-based material as a raw material. In addition, the temperature (melting temperature) at which the copper-based material is melted, the holding time at the melting temperature, and the cooling rate of the molten metal after the holding time are as shown in Table 1.

This casting was subjected to a homogenization heat treatment step [Step 2] of heat treatment at a heating temperature of 800°C and a holding time of 5 hours, and then a hot working step [Step 3] of elongation in the longitudinal direction at a processing temperature of 800°C to achieve a total processing rate of 67% (thickness before processing: 30 mm, thickness after processing: 10 mm), to obtain a hot-worked material. After cooling to room temperature by water cooling, plane cutting was performed to remove the oxide film formed on the surface. The thickness of the hot-worked material after plane cutting was 8 mm.

For the hot-worked material after the hot-work step [step 3], a first cold-working step [step 4] of rolling along the long side direction with a total working rate of 88% (thickness before working is 8 mm, thickness after working is 1 mm) is performed. Then, for the cold-rolled material after the first cold-working step [step 4], a first annealing step [step 5] of heat treatment is performed by setting the holding time at a heating temperature of 600°C or more and 800°C or less to be within the range of 1 minute or more and 2 hours or less is performed.

Furthermore, for the hot-worked material after the first annealing step [step 5], a second cold working step [step 6] of rolling along the long side direction with a total working rate of 70% (thickness before working is 1 mm, thickness after working is 0.3 mm) is performed. Subsequently, for the cold-rolled material after the second cold working step [step 6], a second annealing step [step 7] of heat treatment is performed by setting the holding time at a heating temperature of 600°C or more and 800°C or less to a range of 1 minute or more and 2 hours or less. The copper alloy plates of Examples 1 to 17 of the present invention and Comparative Examples 1 to 6 are manufactured in the above manner.

Furthermore, in Table 1, a horizontal line "-" is written in the column of the component not contained in the alloy composition of the copper-based material, so as to make it clearer that the corresponding component is not contained or even if it is contained, the detection limit value is not reached.

[Various measurement and evaluation methods] The copper alloy materials (copper alloy plates) of the above-mentioned invention examples and comparative examples were used to perform the following property evaluations. The evaluation conditions for each property are as follows.

[1] Determination of the number of coarse precipitated particles containing oxides or carbides For the copper alloy material to be produced, a test material is prepared by embedding the material in a resin so that a cross section perpendicular to the extension direction of the copper alloy material during processing is exposed, and then the cross section perpendicular to the extension direction is polished. Next, the cross section of the polished test material is observed using an optical microscope (manufactured by Olympus, model: GX71) with a 100μm×100μm square as a field of view, and the precipitated particles containing at least one of oxides and carbides represented by black in the microscope image, i.e., coarse precipitated particles with a maximum size exceeding 20μm, are counted. In the present invention and comparative examples, after observing the cross section of the sample material after grinding, the cross section perpendicular to the extension direction of the sample material is further ground to expose the cross section of the sample material at different positions in the extension direction, and then the coarse precipitated particles in the cross section are counted repeatedly to obtain the average value of the number of coarse precipitated particles in 5 fields of view, and the obtained average value is set as the number of coarse precipitated particles. The results are shown in Table 2.

[2] Method for evaluating punching workability The punching workability of the produced copper alloy material is a shear test performed according to 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. That is, the gap between the upper die (punch) and the lower die (die) is adjusted to 10 μm, and the copper alloy material is punched in a rectangular shape with a size of 2 mm along the stretching direction y and a size of 10 mm along the direction intersecting the stretching direction y at right angles (the x direction in Figure 1), thereby producing a copper alloy material 1 having a cut surface 2 on the outer edge.

FIG. 1 is a schematic diagram showing a cross-section when the copper alloy material of the present invention is subjected to a punching process. The copper alloy material 1 shown in FIG. 1 shows a cross-section 2 after the punching process, and the punching process is performed by lowering the upper die (punch) while being fixed on a lower die (punch) not shown. Here, the cross-section 2 is formed with a collapsed angle 3, a shear surface 4, and a fracture surface 5 in sequence from the top surface 1a side of the copper alloy material 1 after the punching process. In addition, burrs 6 are mostly formed at the lower edge of the cross-section 2 in a manner extending outward from the fracture surface 5. Therefore, the cross-section of the copper alloy material 1 including the thickness direction and the width direction includes the collapsed angle 3, the shear surface 4, the fracture surface 5, and the burrs 6.

In this embodiment, the surface of the formed cross-sectional surface 2 along the direction intersecting the extension direction y at right angles, that is, the cross-sectional surface including the thickness direction z and the width direction x, was observed at a magnification of 200 times using a scanning electron microscope (SEM) (SSX-550 (trade name) manufactured by Shimadzu Corporation). Then, based on the scanning electron microscope (SEM) photograph of the cross-sectional surface 2, the ratio of the cross-sectional area of the shear surface 4 to the cross-sectional area of the cross-sectional surface including the thickness direction and the width direction was calculated.

Regarding the ratio of the calculated cross-sectional area of the shear surface 4 to the cross-sectional area of the cross section including the thickness direction and the width direction, the case of 40% or more was set as excellent punching workability and evaluated as "◎". In addition, the case of the cross-sectional area of the shear surface 4 to the cross-sectional area of the cross section including the thickness direction and the width direction was 35% or more but less than 40%, which was set as good punching workability and evaluated as "○". On the other hand, the case of less than 35% was set as poor punching workability and evaluated as "×". The results are shown in Table 2.

[3] Measurement 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.

The volume resistivity ρ is measured by setting the voltage terminal distance to 200 mm and the measuring current to 100 mA at room temperature 20°C using the four-terminal method in accordance with the method specified in JIS C2525, and the volume resistivity ρ [μΩ・cm] is calculated from the obtained value.

For the measured volume resistivity ρ, the case where the volume resistivity ρ is 80μΩ·cm or more is set as a resistor material with sufficiently large volume resistivity ρ and excellent, and is evaluated as "◎". In addition, the case where the volume resistivity ρ is 70μΩ·cm or more and less than 80μΩ·cm is set as a resistor material with large volume resistivity ρ and good, and is evaluated as "○". On the other hand, the case where the volume resistivity ρ is less than 70μΩ·cm is set as a resistor material with small volume resistivity ρ and poor, and is evaluated as "×". In this embodiment, "◎" and "○" are evaluated as qualified grades. The results are shown in Table 2.

[4] 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 material was carried out in accordance with JIS C2527. More specifically, as shown in FIG. 2 , the device 10 for measuring the thermoelectromotive force (EMF) of the sample material 11 with respect to copper uses a fully annealed pure copper wire with a diameter of less than 1 mm as the standard copper wire 21, and uses a voltage measuring device 43 to measure the electromotive force when: the temperature measuring junction _P1 connecting the sample material 11 and one end of the standard copper wire 21 is immersed in warm water kept at 80°C in a constant temperature bath 41, and the reference junctions _P21 and _P22 connecting the other ends of the sample material 1 and the standard copper wire 2 to the copper wires 31 and 32, respectively, are immersed in ice water at 0°C kept in an ice point device 42. The obtained electromotive force was divided by the temperature difference, 80[℃], to obtain the thermoelectric force (EMF) (μV/℃) on copper.

For the measured EMF to copper, the case where the absolute value was 0.6 μV/℃ or less was regarded as a good resistor material with a small absolute value of EMF to copper and was evaluated as "○". On the other hand, the case where the absolute value of EMF to copper was greater than 0.6 μV/℃ was regarded as a poor resistor material with a large absolute value of EMF to copper and was evaluated as "×". The results are shown in Table 2.

[5] Comprehensive evaluation The following cases were evaluated as excellent in the three characteristics of press workability, volume resistivity ρ, and copper thermoelectrodynamic force (EMF) and were rated as "◎": Among the three evaluation results related to press workability, volume resistivity ρ, and copper thermoelectrodynamic force (EMF), both the evaluation results of press workability and volume resistivity ρ were rated as "◎", and the evaluation results of copper thermoelectrodynamic force (EMF) were rated as "○". In addition, the following cases are set as at least good and evaluated as "○": among the three evaluation results, one or both of the evaluation results of the punching workability and the volume resistivity ρ and the thermoelectric dynamic force (EMF) of copper are evaluated as "○", and the rest are evaluated as "◎". On the other hand, the following cases are set as at least any one of the three characteristics is unqualified and evaluated as "×": the evaluation result of at least any one of the punching workability, the volume resistivity ρ and the thermoelectric dynamic force (EMF) of copper is "×". The results are shown in Table 2.

[Table 1]

[Table 2]

According to the results of Table 1 and Table 2, the copper alloy materials of Examples 1 to 17 of the present invention have alloy compositions within the appropriate and correct range of the present invention, and the number of coarse precipitated particles containing at least one of oxides and carbides when observed in a cross section perpendicular to the stretching direction is 3 or less, and therefore are evaluated as "◎" or "0" in the evaluation of volume resistivity ρ and punching workability. In addition, regarding the thermoelectric force (EMF) of copper, the copper alloy materials of Examples 1 to 17 of the present invention are all evaluated as "0".

On the other hand, the copper alloy material of Comparative Example 1 has a small total amount of O and C, and the alloy composition is outside the appropriate and correct range of the present invention. Therefore, the copper alloy material of Comparative Example 1 is evaluated as "×" with respect to the punching workability.

In addition, the total amount of O and C in the copper alloy material of Comparative Example 2 is large and outside the appropriate and correct range of the present invention. Therefore, the copper alloy material of Comparative Example 2 cracks during the press delay in the hot working step [Step 3].

Furthermore, the Mn content of the copper alloy material of Comparative Example 3 is small, and the alloy composition is outside the appropriate and correct range of the present invention. Therefore, regarding the volume resistivity ρ, the copper alloy material of Comparative Example 3 is evaluated as "×".

Furthermore, the copper alloy material of Comparative Example 4 has a high Mn content and the alloy composition is outside the appropriate and correct range of the present invention. Therefore, the copper alloy material of Comparative Example 4 is evaluated as "×" with respect to the copper thermoelectric force (EMF).

Furthermore, the content of Ni in the copper alloy material of Comparative Example 5 was relatively high, and the alloy composition was outside the appropriate and correct range of the present invention. Therefore, the copper alloy material of Comparative Example 5 was evaluated as "×" with respect to the copper thermoelectric force (EMF).

Furthermore, the Ni content of the copper alloy material of Comparative Example 6 was small, and the alloy composition was outside the appropriate and correct range of the present invention. Therefore, the copper alloy material of Comparative Example 6 was evaluated as "×" with respect to the copper thermoelectric force (EMF).

Based on this result, it was confirmed that the copper alloy material of the present invention example has at least good volume resistivity ρ and copper thermoelectric motive force (EMF) when the alloy composition is within the appropriate and correct range of the present invention. At the same time, it was confirmed that the copper alloy material of the present invention example also has at least good stamping workability.

FIG3 shows an example of an optical microscope photograph of a cross section perpendicular to the extension direction during processing of the copper alloy material of Example 9 of the present invention observed within a field of view of 10000 μm ^2. In this optical microscope photograph, precipitated particles containing at least one of oxides and carbides are represented as black dots. According to the optical microscope photograph of FIG3, it is confirmed that precipitated particles with a maximum size exceeding 20 μm, i.e., coarse precipitated particles, are not precipitated within the field of view as precipitated particles containing at least one of oxides and carbides.

In addition, Fig. 4 and Fig. 5 show scanning electron microscope (SEM) photographs of the cross-section when the copper alloy materials of the present invention and the comparative example are punched and processed, and the cross-section observation includes the thickness direction and the width direction. Here, Fig. 4 is a SEM photograph of the cross-section when the copper alloy material of the present invention example 11 is punched and processed, and Fig. 5 is a SEM photograph of the cross-section when the copper alloy material of the comparative example 1 is punched and processed. Furthermore, in Fig. 4 and Fig. 5, the boundaries of the shear plane 4, 400 and the fracture plane 5, 500 are indicated by dotted lines. From these SEM images, it is confirmed that the ratio of the cross-sectional area of the shear plane 400 in the copper alloy material 100 of the comparative example is larger than that of the cross-sectional area of the shear plane 4 in the copper alloy material 1 of the present invention example relative to the cross-sectional area of the cross section including the thickness direction and the width direction.

1: Copper alloy material 1a: Top surface of copper alloy material 1b: Bottom surface of copper alloy material 2,200: Cut surface 3,300: Collapse angle 4,400: Shear surface 5,500: Fracture surface 6,600: Burr 7: Boundary line 10: Copper thermoelectromotive force (EMF) measuring device 11: Test material 21: Standard copper wire 31,32: Copper wire 41: Constant temperature bath 42: Freezing point device 43: Voltage measuring device 100: Comparative example copper alloy material 100a: Top surface of comparative example copper alloy material 100b: Bottom surface of comparative example copper alloy material _P1 : Temperature measurement junction _P21 , _P22 : Reference junction x: Width direction y: Extension direction z: Thickness direction

FIG1 is a schematic diagram showing a cross section of the copper alloy material of the present invention when punching is performed. FIG2 is a schematic diagram of an apparatus for measuring the thermoelectric force (EMF) of copper for the test materials of the present invention and the comparative example. FIG3 shows an example of an optical microscope photograph of the cross section of the copper alloy material of Example 9 of the present invention, which is perpendicular to the extension direction during processing, when observed within a field of view of 10,000 μm ^2. FIG4 shows a scanning electron microscope (SEM) photograph of the cross section of the copper alloy material of Example 11 of the present invention when the cross section is observed in the thickness direction and the width direction when punching is performed. FIG. 5 shows a scanning electron microscope (SEM) photograph of a cross-section of the copper alloy material of Comparative Example 1 when the copper alloy material is subjected to stamping, taken in a cross-sectional observation including the thickness direction and the width direction.

Domestic storage information (please note in the order of storage institution, date, and number) None Foreign storage information (please note in the order of storage country, institution, date, and number) None

Claims (5)

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, and simultaneously containing 0 mass ppm or more and 800 mass ppm or less of O and 0 mass ppm or more and 800 mass ppm or less of C, wherein the total amount of O and C is 60 mass ppm or more and 800 mass ppm or less, and the remainder includes Cu and unavoidable impurities. The copper alloy material as described in claim 1, wherein, in a cross-section observation of the copper alloy material perpendicular to the extension direction during processing, among the precipitated particles containing at least one of oxides and carbides observed within a field of view of ¹⁰⁰⁰⁰ μm2, the number of precipitated particles having a maximum size exceeding 20 μm, i.e., coarse precipitated particles, is 3 or less. The copper alloy material as described in claim 1, wherein the alloy composition further contains at least one component selected from the group consisting of: 0.01 mass% to 0.50 mass% Fe, 0.01 mass% to 2.00 mass% Co, 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 comprises the copper alloy material described in any one of claims 1 to 3. A resistor having the resistor material for the resistor as described in claim 4.