Copper alloy material, and resistive material for resistors, resistor, material for heating elements, and heating element each using said copper alloy material

Abstract

The present invention provides: a copper alloy material which has a volume resistivity within a desired range, has a thermal electromotive force against copper having a small absolute value, and has a temperature coefficient of resistance of 0 or a negative number having a small absolute value over a wide temperature range from a normal temperature (for example, 20° C) to a high temperature (for example, 150° C); and a resistive material for resistors, a resistor, a material for heating elements, and a heating element, each using said copper alloy material.　This copper alloy material has an alloy composition that contains from 7.0% by mass to 17.0% by mass of Mn, from 0.1% by mass to 3.0% by mass of Ni, and from 1.0% by mass to 5.0% by mass of Al, with the balance being made up of Cu and unavoidable impurities. The resistive material for resistors and the material for heating elements are composed of this copper alloy material. The resistor comprises this resistive material for resistors. The heating element comprises this material for heating elements.

Description

Copper alloy material, and resistance material for resistors, resistors, materials for heating elements, and heating elements using the same

[0001] The present invention relates to a copper alloy material, and a resistive material for resistors, resistors, materials for heating elements, and heating elements using the same.

[0002] Cu-Mn-Ni alloys are widely used as copper-based resistance materials for resistors. These Cu-Mn-Ni alloys are known to have a high volume resistivity ρ and a small absolute value of the temperature coefficient of resistance (TCR) due to their high manganese content. The temperature coefficient of resistance (TCR) here refers to the magnitude of the change in resistance value due to temperature, expressed in parts per million (ppm) per degree Celsius. The TCR (×10 －６ / ° C) = {(R - R ０ ) / R ０}×{1 / (T-T ０ )} x 10 ６ where T is the test temperature (°C), T ０ is the reference temperature (°C), R is the resistance value (Ω) at the test temperature T, R ０ is the reference temperature T ０ The resistance value (Ω) at

[0003] As an example of a Cu-Mn-Ni alloy, Non-Patent Document 1 describes an alloy symbolized as GCM44, which contains Mn in the range of 10.0 mass % to 13.0 mass % and Ni in the range of 1.0 mass % to 4.0 mass %, with the total amount of Cu + Mn + Ni being 98.0 mass % or more, and has an electrical resistance (volume resistivity ρ) of 44 [μΩ cm].

[0004] Japanese Industrial Standards JIS C2532; 1999

[0005] Such conventional copper alloys are used not only in resistors but also in heating elements such as heater wires, and are characterized by a small temperature dependency of electrical resistance in an operating environment of, for example, 100° C. or less, resulting in a small positive temperature coefficient of resistance (TCR). However, in an operating environment of higher temperatures, for example, 150° C., the resistance value decreases significantly, resulting in the copper alloy's temperature coefficient of resistance (TCR) becoming a large negative number.

[0006] In recent years, there has been a demand for high-precision copper alloys that can withstand larger currents and higher-temperature operating environments, and it has been desirable for the resistance value to fluctuate little over a temperature range from room temperature (e.g., 20°C) to 150°C. Conventional copper alloys are characterized by a small, positive temperature coefficient of resistance (TCR) in operating environments below 100°C, for example. However, metals commonly used for electrodes have a positive TCR due to a positive correlation with the temperature dependence of their volume resistivity ρ. Therefore, even if a copper alloy with a small, positive TCR is used in a resistor or heating element, the TCR of the resistor or heating element as a whole is affected by the electrode material, resulting in a larger, positive TCR. Therefore, a copper alloy with a material TCR of 0 or negative and a small absolute value has been sought as a copper alloy with low temperature dependence of electrical resistance even when the presence of an electrode material is taken into account.

[0007] Furthermore, copper alloys used in resistors and heating elements preferably have a high volume resistivity ρ in order to improve the precision of the resistors, but if the resistance value is made higher than necessary, there is a problem in that the power consumption of the resistor or heating element increases, and in particular, energy loss due to heat generation increases. Therefore, there has been a demand for copper alloys that can be used in resistors and heating elements and that have an appropriate volume resistivity ρ in a range that allows them to reduce energy loss due to heat generation.

[0008] In particular, copper alloys used in heating elements achieve desired resistance values ​​and heat generation amounts by changing their cross-sectional area, but if the resistance value is larger than necessary, the cross-sectional area of ​​the heating element must be increased, which can reduce the workability of the heating element and increase its weight. In addition, when the temperature coefficient of resistance (TCR) is a large positive number as described above, the resistance value increases within the operating temperature range, causing problems in temperature control. Therefore, there has been a demand for copper alloys with an appropriate volume resistivity ρ and a small absolute value of the temperature coefficient of resistance (TCR).

[0009] Furthermore, since copper alloys used in resistors and heating elements are often connected to copper, there has been a demand for copper alloys with a small electromotive force at the bonding interface with copper, i.e., copper alloys with a small absolute value of thermoelectromotive force (EMF) against copper.

[0010] Therefore, an object of the present invention is to provide a copper alloy material having a volume resistivity in a desired range, a small absolute value of thermoelectromotive force against copper, and a temperature coefficient of resistance that is 0 or a negative number with a small absolute value over a wide temperature range from room temperature (e.g., 20°C) to high temperature (e.g., 150°C), as well as a resistance material for resistors, a resistor, a material for heating elements, and a heating element using the same.

[0011] The present inventors have found that an alloy composition containing 7.0 mass % or more and 17.0 mass % or less of Mn, 0.1 mass % or more and 3.0 mass % or less of Ni, and 1.0 mass % or more and 5.0 mass % or less of Al, with the remainder being Cu and unavoidable impurities, can provide a copper alloy material having a volume resistivity ρ within a desired range, a small absolute value of copper thermoelectromotive force (EMF), and a temperature coefficient of resistance that is 0 or a negative number and has a small absolute value over a wide temperature range from room temperature (e.g., 20°C) to a high temperature (e.g., 150°C), and have thereby completed the present invention.

[0012] In order to achieve the above object, the present invention provides the following essential configurations: (1) A copper alloy material having an alloy composition containing 7.0% by mass or more and 17.0% by mass or less of Mn, 0.1% by mass or more and 3.0% by mass or less of Ni, and 1.0% by mass or more and 5.0% by mass or less of Al, with the balance being Cu and unavoidable impurities. (2) The copper alloy material according to (1) above, in which the Mn content in the alloy composition is 7.0% by mass or more and 14.0% by mass or less. (3) The copper alloy material according to (1) or (2) above, in which the alloy composition further contains 0.01% by mass or more and 1.30% by mass or less of Co. (4) The copper alloy material according to (3) above, in which the alloy composition further contains 0.01% by mass or more and 0.30% by mass or less of Fe. (5) The copper alloy material according to any one of (1) to (4) above, wherein the alloy composition further contains one or more components selected from the group consisting of Sn: 0.01% by mass to 2.00% by mass, Zn: 0.01% by mass to 3.00% by mass, Cr: 0.01% by mass to 0.50% by mass, Ag: 0.01% by mass to 0.50% by mass, Mg: 0.01% by mass to 0.50% by mass, Si: 0.01% by mass to 0.50% by mass, and P: 0.01% by mass to 0.50% by mass. (6) The copper alloy material according to any one of (1) to (5) above, having a metal structure with an average crystal grain size of 40 μm or less. (7) A resistive material for a resistor, comprising the copper alloy material according to any one of (1) to (6) above. (8) A resistor, comprising the resistive material for a resistor according to (7) above. (9) A material for a heating element, comprising the copper alloy material according to any one of (1) to (6) above. (10) A heating element, comprising the material for a heating element according to (9) above.

[0013] According to the present invention, it is possible to provide a copper alloy material having a volume resistivity in a desired range, a small absolute value of thermoelectromotive force against copper, and a temperature coefficient of resistance that is 0 or a negative number with a small absolute value over a wide temperature range from room temperature (e.g., 20°C) to a high temperature (e.g., 150°C), as well as a resistance material for resistors, a resistor, a material for heating elements, and a heating element using the same.

[0014] FIG. 1 is a schematic diagram for explaining a method for determining the thermoelectromotive force (EMF) against copper for test materials of an example of the present invention and a comparative example.

[0015] Hereinafter, preferred embodiments of the copper alloy material of the present invention will be described in detail. In the component composition of the alloy of the present invention, "mass %" may be simply represented as "%".

[0016] The copper alloy material according to the present invention has an alloy composition containing 7.0 mass% or more and 17.0 mass% or less of Mn, 0.1 mass% or more and 3.0 mass% or less of Ni, and 1.0 mass% or more and 5.0 mass% or less of Al, with the balance being Cu and unavoidable impurities.

[0017] The copper alloy material of the present invention contains Mn in the range of 7.0% by mass to 17.0% by mass, Ni in the range of 0.1% by mass to 3.0% by mass, and Al in the range of 1.0% by mass to 5.0% by mass. This reduces the absolute value of the thermoelectric power (EMF) generated between 0°C and 80°C (hereinafter, sometimes simply referred to as "thermoelectric power") compared to a material not containing Al. This allows for higher precision resistors and higher performance heating elements, even in high-temperature environments. Furthermore, by containing Mn in the range of 7.0% by mass to 17.0% by mass and Ni in the range of 0.1% by mass to 3.0% by mass, the volume resistivity ρ can be adjusted within a desired range. As a result, the copper alloy material of the present invention has a volume resistivity ρ within a range useful as a resistance material or heating element material with low energy loss due to heat generation, and the absolute value of the thermoelectric power (EMF) against copper can be reduced.

[0018] Furthermore, the copper alloy material according to the present invention can also reduce the absolute value of the temperature coefficient of resistance (TCR) (hereinafter, sometimes simply referred to as "temperature coefficient of resistance") over a wide temperature range from room temperature (e.g., 20°C) to high temperature (e.g., 150°C). More specifically, by containing Mn in a range of 7.0 mass% to 17.0 mass% and Al in a range of 1.0 mass% to 5.0 mass%, the temperature coefficient of resistance (TCR) can be set to 0 or a small absolute value over a temperature range from 20°C to 150°C, including higher temperatures. This reduces the adverse effects of a high temperature coefficient of resistance of a conductor metal bonded to the copper alloy material when the copper alloy material is used as a resistive material for resistors and the like. For example, when the conductor metal is copper, the temperature coefficient of resistance of copper is large, about 4000 ppm / °C, and therefore, the resistance value varies depending on the temperature change of the conductor. Even when such a metal is used, by combining it with the copper alloy material of the present invention, it is possible to reduce the adverse effect on the resistance value of the conductor due to temperature changes.

[0019] In this regard, the copper alloy described in the above-mentioned Non-Patent Document 1 has an average temperature coefficient of +50×10 in the temperature range from 23°C to 100°C regarding the temperature dependence of electrical resistance. －６ [℃ －１ However, the copper alloy described in Non-Patent Document 1 exhibits a large decrease in electrical resistance at high temperatures close to 150°C, and therefore has a large negative temperature coefficient of resistance (TCR) in the temperature range from 20°C to 150°C, which includes higher temperatures, and therefore is prone to errors in resistance values, particularly in the high temperature range. In this regard, the copper alloy material according to the present invention can have a temperature coefficient of resistance (TCR) of 0 or a negative number with a small absolute value over a wide temperature range from room temperature (e.g., 20°C) to high temperatures (e.g., 150°C).

[0020] Therefore, the copper alloy material according to the present invention has a volume resistivity ρ in a desired range, a small absolute value of the thermoelectromotive force (EMF) against copper, and a temperature coefficient of resistance (TCR) that is 0 or a negative number with a small absolute value, and it is also possible to provide a copper alloy material, as well as a resistance material for resistors, resistors, materials for heating elements, and heating elements using the copper alloy material.

[0021] [1] Composition of copper alloy material <Essential components> The alloy composition of the copper alloy material of the present invention contains, as essential components, Mn: 7.0 mass% or more and 17.0 mass% or less, Ni: 0.1 mass% or more and 3.0 mass% or less, and Al: 1.0 mass% or more and 5.0 mass% or less.

[0022] (Mn: 7.0% by mass or more and 17.0% by mass or less) Mn (manganese) is an element that increases the volume resistivity ρ and adjusts the temperature coefficient of resistance (TCR) in the negative direction, making it easier to obtain a large absolute negative value for the temperature coefficient of resistance (TCR). Therefore, the Mn content is preferably 7.0% by mass or more, more preferably 9.0% by mass or more, and even more preferably 10.0% by mass or more. In particular, the effect of making the temperature coefficient of resistance (TCR) negative is greatly influenced by increasing the Mn content. On the other hand, if the Mn content exceeds 17.0% by mass, the volume resistivity ρ becomes too high, and it becomes difficult to reduce the absolute values ​​of the thermoelectric power (EMF) and the temperature coefficient of resistance (TCR). For this reason, the Mn content is 17.0% by mass or less, and preferably 14.0% by mass or less. More specifically, the Mn content in the alloy composition is preferably in the range of 7.0% by mass or more and 14.0% by mass or less. In particular, when the first optional additional component described below is not contained, the Mn content is preferably 14.0 mass % or less from the viewpoint of further reducing the absolute value of the thermoelectromotive force (EMF) against copper.

[0023] (Ni: 0.1% by mass or more and 3.0% by mass or less) Ni (nickel) is an element that reduces the absolute value of the thermoelectromotive force (EMF) against copper, and can adjust the thermoelectromotive force (EMF) against copper, which becomes a large negative number due to the addition of Mn, in the positive direction. To exert this effect, Ni is preferably contained in an amount of 0.1% by mass or more. On the other hand, if the Ni content exceeds 3.0% by mass, it is likely to form a compound with aluminum, as described below, and therefore the effect of reducing the absolute value of the thermoelectromotive force (EMF) against copper cannot be sufficiently obtained. For this reason, the Ni content is in the range of 0.1% by mass or more and 3.0% by mass or less.

[0024] (Al: 1.0% by mass or more and 5.0% by mass or less) Al (aluminum) is an element that reduces the absolute value of the temperature coefficient of resistance (TCR). To achieve this effect, it is preferable to contain 1.0% by mass or more of Al. On the other hand, if the Al content exceeds 5.0% by mass, Al is likely to form compounds with Mn and Ni, and therefore the effect of reducing the absolute value of the temperature coefficient of resistance (TCR) and the effect of reducing the absolute value of the thermoelectric power (EMF) against copper cannot be sufficiently obtained. For this reason, the Al content is in the range of 1.0% by mass or more and 5.0% by mass or less.

[0025] <First optional additional component> The alloy composition of the copper alloy material of the present invention may further contain, as a first optional additional component, one or both of Co: 0.01 mass% or more and 1.30 mass% or less and Fe: 0.01 mass% or more and 0.30 mass% or less.

[0026] (Co: 0.01 mass% or more and 1.30 mass% or less) In particular, the alloy composition of the copper alloy material of the present invention preferably further contains Co (cobalt) in a range of 0.01 mass% or more and 1.30 mass% or less as a first optional added component, in addition to the above-mentioned Mn, Ni, and Al.

[0027] Cobalt is unlikely to form compounds with other elements and to precipitate, so even when used for a long period of time as a resistance material, it can stably reduce the absolute value of the thermoelectric power (EMF) against copper. To achieve this effect, Co is preferably contained in an amount of 0.01% by mass or more, more preferably 0.10% by mass or more. In particular, in the copper alloy material of the present invention, the effect of containing Co is similar to the effect of containing Ni, but the amount of Co required to reduce the absolute value of the thermoelectric power (EMF) against copper is smaller than that of Ni. Furthermore, the addition of Co reduces the amount of Ni required to obtain the desired thermoelectric power (EMF) against copper, thereby suppressing the formation of Ni and Al compounds, and as a result, improving the electrical performance of the copper alloy material. On the other hand, if the Co content exceeds 1.30% by mass, the properties of the copper alloy material tend to vary greatly. Therefore, the Co content is preferably 1.30% by mass or less. In order to obtain a copper alloy material having a particularly small absolute value of the thermoelectromotive force (EMF) against copper, the Co content may be 0.80 mass% or less. Therefore, the Co content is preferably in the range of 0.01 mass% to 1.30 mass%, more preferably in the range of 0.10 mass% to 1.30 mass%.

[0028] (Fe: 0.01 mass% or more and 0.30 mass% or less) The alloy composition of the copper alloy material of the present invention preferably further contains, as a first optional added component, Fe (iron) in a range of 0.01 mass% or more and 0.30 mass% or less in addition to the above-mentioned Co.

[0029] Fe is an element that reduces the absolute value of the thermoelectric power (EMF) against copper. To achieve this effect, Fe is preferably contained in an amount of 0.01% by mass or more. In the copper alloy material of the present invention, the addition of Fe can achieve the same effect as Co, and adding Fe is particularly effective from the viewpoint of reducing costs. However, when Fe is contained as the first optional additive component, Fe is an element that easily forms compounds with other elements and easily precipitates, so that changes in electrical properties such as volume resistivity and thermoelectric power (EMF) against copper may occur when used for a long period of time as a resistance material, etc. Therefore, from the viewpoint of minimizing changes in electrical properties due to heat, etc., and thereby improving reliability when used for a long period of time as a resistance material, etc., the Fe content is preferably 0.30% by mass or less, more preferably 0.15% by mass or less. Therefore, the Fe content is preferably in the range of 0.01% by mass or more to 0.30% by mass or less, more preferably 0.01% by mass or more to 1.50% by mass or less.

[0030] Furthermore, from the viewpoint of further improving reliability when used for a long period of time as a resistance material, the Fe content is preferably less than the Co content, and in this case the Fe content may be 0.

[0031] <Second Optionally Added Component> The alloy composition of the copper alloy material of the present invention may further contain, as a second optional added component, one or more components selected from the group consisting of Sn: 0.01 mass% or more and 2.00 mass% or less, Zn: 0.01 mass% or more and 3.00 mass% or less, Cr: 0.01 mass% or more and 0.50 mass% or less, Ag: 0.01 mass% or more and 0.50 mass% or less, Mg: 0.01 mass% or more and 0.50 mass% or less, Si: 0.01 mass% or more and 0.50 mass% or less, and P: 0.01 mass% or more and 0.50 mass% or less.

[0032] (Sn: 0.01 mass% or more and 2.00 mass% or less) Sn (tin) is a component that can be used to adjust the volume resistivity ρ. To exert this effect, it is preferable to contain 0.01 mass% or more of Sn. On the other hand, by setting the Sn content to 2.00 mass% or less, it is possible to make it difficult for a decrease in the manufacturability of the copper alloy material to occur.

[0033] (Zn: 0.01% by mass or more and 3.00% by mass or less) Zn (zinc) is a component that can be used to adjust the volume resistivity ρ. To achieve this effect, it is preferable to contain Zn at 0.01% by mass or more. On the other hand, the Zn content may adversely affect the long-term stability of electrical performance such as the volume resistivity ρ, temperature coefficient of resistance (TCR), and thermoelectric power (EMF) against copper, so it is preferable to keep it at 3.00% by mass or less.

[0034] (Cr: 0.01% by mass or more and 0.50% by mass or less) Cr (chromium) is a component that can be used to adjust the volume resistivity ρ. To achieve this effect, it is preferable to contain 0.01% by mass or more of Cr. On the other hand, the Cr content may adversely affect the long-term stability of electrical performance such as the volume resistivity ρ, temperature coefficient of resistance (TCR), and thermoelectric power (EMF) against copper, so it is preferable to keep it at 0.50% by mass or less.

[0035] (Ag: 0.01% by mass or more and 0.50% by mass or less) Silver (Ag) is a component that can be used to adjust the volume resistivity ρ. To achieve this effect, it is preferable to contain 0.01% by mass or more of Ag. On the other hand, the Ag content may adversely affect the long-term stability of electrical performance such as the volume resistivity ρ, temperature coefficient of resistance (TCR), and thermoelectric power (EMF) against copper, so it is preferable to keep it at 0.50% by mass or less.

[0036] (Mg: 0.01% by mass or more and 0.50% by mass or less) Mg (magnesium) is a component that can be used as a deoxidizer during casting. To achieve this effect, it is preferable to contain 0.01% by mass or more of Mg. On the other hand, the Mg content may adversely affect the long-term stability of electrical performance such as volume resistivity ρ, temperature coefficient of resistance (TCR), and thermoelectric power (EMF) against copper, so it is preferable to keep it at 0.50% by mass or less.

[0037] (Si: 0.01% by mass or more and 0.50% by mass or less) Si (silicon) is a component that can be used as a deoxidizer during casting. To exert this effect, it is preferable to contain 0.01% by mass or more of Si. On the other hand, the Si content may adversely affect the long-term stability of electrical performance such as volume resistivity ρ, temperature coefficient of resistance (TCR), and thermoelectric power (EMF) against copper, so it is preferable to keep it at 0.50% by mass or less.

[0038] (P: 0.01% by mass or more and 0.50% by mass or less) P (phosphorus) is a component that can be used as a deoxidizer during casting. To exert this effect, it is preferable to contain 0.01% by mass or more of P. On the other hand, the P content may adversely affect the long-term stability of electrical performance such as volume resistivity ρ, temperature coefficient of resistance (TCR), and thermoelectric power (EMF) against copper, so it is preferable to keep it at 0.50% by mass or less.

[0039] (Total Amount of Second Optional Additive Components: 0.01% by Mass or More and 3.00% by Mass or Less) In order to obtain the effects of the second optional additive components, the second optional additive components composed of one or more components selected from the group consisting of Sn, Zn, Cr, Ag, Mg, Si, and P are preferably contained in a total amount of 0.01% by mass or more. On the other hand, the content of these second optional additive components may adversely affect the stability of electrical performance such as volume resistivity ρ, temperature coefficient of resistance (TCR), and thermoelectric power (EMF) over a long period of time, and may also reduce the manufacturability of the copper alloy material, so the total content is preferably 3.00% by mass or less.

[0040] <Balance: Cu and Inevitable Impurities> Apart from the essential components and optional components described above, the balance consists of Cu (copper) and inevitable impurities. The term "inevitable impurities" as used herein generally refers to impurities present in raw materials or unavoidably mixed in during the manufacturing process of copper-based products. These impurities are essentially unnecessary but tolerated in trace amounts because they do not affect the properties of the copper-based product. Examples of components that can be cited as inevitable impurities include nonmetallic elements such as sulfur (S), carbon (C), and oxygen (O), and metallic elements such as antimony (Sb). The upper limit of the content of these components can be 0.05% by mass for each component, or 0.10% by mass for the total amount of the components.

[0041] [2] Shape and Metallographic Structure of Copper Alloy Material The shape of the copper alloy material of the present invention is not particularly limited, and can be various forms such as plate, wire, rectangular wire, ribbon, and tube. However, from the viewpoint of facilitating the hot or cold processing steps described below, plate, bar, strip, or wire is preferred. Among these, in copper alloy materials formed by rolling, such as plate and strip, the rolling direction can be the elongation direction. Furthermore, in copper alloy materials formed by wire drawing, drawing, or extrusion, such as wire such as rectangular wire and round wire, or rod, any of the wire drawing direction, drawing direction, and extrusion direction can be the elongation direction.

[0042] Furthermore, the copper alloy material of the present invention preferably has a metal structure having an average crystal grain size of 40 μm or less. Here, by setting the average crystal grain size of the crystals contained in the metal structure of the copper alloy material to 40 μm or less, the yield strength of the alloy can be increased, thereby making the copper alloy material less likely to break. Note that the average crystal grain size of the crystals is measured in a plane perpendicular to the stretching direction when the crystals are not formed equiaxed and there is anisotropy in the crystal grain size due to processing such as rolling or wire drawing along the stretching direction.

[0043] Here, the measurement of the average grain size in this specification can be performed in accordance with the grain size test method for drawn copper products described in JIS H0501. More specifically, a test material is prepared by embedding the copper alloy material in a resin so that the cross section is exposed, and then the cross section perpendicular to the stretching direction is polished, followed by wet etching using a chromic acid aqueous solution, and the exposed grains are observed with a scanning electron microscope (SEM) to measure the grain size (or grain size). In particular, when measuring the average grain size in a plane perpendicular to the stretching direction, the copper alloy material is embedded in a resin so that the cross section perpendicular to the stretching direction is exposed to prepare a test material.

[0044] [3] Example of a manufacturing method for a copper alloy material The above-mentioned copper alloy material can be realized by controlling a combination of alloy composition and manufacturing process, and the manufacturing process is not particularly limited. Among them, the following method can be cited as an example of a manufacturing process that can obtain the above-mentioned copper alloy material.

[0045] In one example of a method for producing a copper alloy material according to the present invention, a copper alloy material having substantially the same alloy composition as that of the copper alloy material described above is sequentially subjected to at least a casting step (step 1), a homogenization heat treatment step (step 2), a hot working step (step 3), a cold working step (step 4), and an annealing step (step 5). In the casting step (step 1), the copper alloy material is melted in an inert gas atmosphere or in a vacuum to produce an ingot. In the homogenization heat treatment step (step 2), the heating temperature is set to a range of 750°C to 900°C, and the holding time at the heating temperature is set to a range of 10 minutes to 10 hours. In the annealing step (step 5), the heating temperature is set to a range of 600°C to 800°C, and the holding time at the heating temperature is set to a range of 1 minute to 2 hours.

[0046] (i) Casting step [Step 1] In the casting step [Step 1], a copper alloy material having the above-described alloy composition is melted in an inert gas atmosphere or in a vacuum using a high-frequency melting furnace, and then cast into an ingot of a predetermined shape (e.g., thickness 30 mm, width 50 mm, length 300 mm). Note that the alloy composition of the copper alloy material may not always be completely identical to that of the copper alloy material produced due to the adhesion or volatilization of added components in the melting furnace in each manufacturing step, but it has substantially the same alloy composition as that of the copper alloy material.

[0047] (ii) Homogenization Heat Treatment Step [Step 2] The homogenization heat treatment step [Step 2] is a step of performing a heat treatment for homogenization on the ingot after the casting step [Step 1]. Here, the conditions for the heat treatment in the homogenization heat treatment step [Step 2] are preferably a heating temperature in the range of 750°C to 900°C and a holding time at the heating temperature in the range of 10 minutes to 10 hours, from the viewpoint of suppressing coarsening of crystal grains.

[0048] (iii) Hot Working Step [Step 3] The hot working step [Step 3] is a step in which the ingot that has undergone homogenization heat treatment is subjected to hot rolling or wire drawing until it reaches a predetermined thickness and dimensions, thereby producing a hot-rolled material. Here, the hot working step [Step 3] includes both a hot rolling step and a hot drawing (wire drawing) step. Furthermore, the conditions for the hot working step [Step 3] are that the working temperature is preferably in the range of 750°C or higher and 900°C or lower, and may be the same as the heating temperature in the homogenization heat treatment step [Step 2]. Furthermore, the working rate in the hot working step [Step 3] is preferably 10% or higher.

[0049] Here, the "processing rate" is a value obtained by subtracting the cross-sectional area after processing such as rolling or wire drawing from the cross-sectional area before processing, dividing the result by the cross-sectional area before processing, and multiplying the result by 100, and expressed as a percentage, and is expressed by the following formula: [Processing rate] = {([Cross-sectional area before processing] - [Cross-sectional area after processing]) / [Cross-sectional area before processing]} x 100 (%)

[0050] The hot-rolled material is preferably cooled after the hot working step [Step 3]. Here, the means for cooling the hot-rolled material is not particularly limited, but from the viewpoint of, for example, making it difficult for crystal grains to become coarse, it is preferable to use a means for increasing the cooling rate as much as possible, and for example, it is preferable to set the cooling rate to 10°C / second or more by means such as water cooling.

[0051] Here, the cooled hot-rolled material may be subjected to facing, in which the surface is scraped off. By performing facing, it is possible to remove the oxide film and defects on the surface that occurred in the hot working step [Step 3]. The conditions for facing may be any conditions that are normally used, and are not particularly limited. The amount of material scraped off from the surface of the hot-rolled material by facing can be appropriately adjusted based on the conditions of the hot working step [Step 3], and can be, for example, about 0.5 mm to 4 mm from the surface of the hot-rolled material.

[0052] (iv) Cold Working Step [Step 4] The cold working step [Step 4] is a step in which the hot-rolled material after the hot working step [Step 3] is subjected to cold rolling, wire drawing, or other processing at an arbitrary processing rate according to the plate thickness, wire diameter, or dimensions of the product. Here, the cold working step [Step 4] includes both a cold rolling step and a cold drawing (wire drawing) step. Furthermore, the conditions for rolling, wire drawing, and the like in the cold working step [Step 4] can be set according to the size of the hot-rolled material. In particular, from the viewpoint of promoting the generation of uniform crystal grains by recrystallization in the annealing step [Step 5] described below, it is preferable that the total processing rate in the cold working step [Step 4] be 50% or more.

[0053] (v) Annealing Step [Step 5] The annealing step [Step 5] is a step of annealing by heat treatment of the cold-rolled material after the cold working step [Step 4] to recrystallize it. Here, the conditions for the heat treatment in the annealing step [Step 5] are that the heating temperature is in the range of 500 ° C or higher and 800 ° C or lower, and the holding time at the heating temperature is in the range of 1 minute or higher and 2 hours or lower. On the other hand, if the heating temperature is lower than 600 ° C or the holding time is shorter than 1 minute, it becomes difficult to recrystallize the copper alloy material. Furthermore, if the heating temperature exceeds 800 ° C or the holding time exceeds 2 hours, the crystal grains become coarse, and the absolute values ​​of the temperature coefficient of resistance (TCR) and the thermoelectric power (EMF) against copper tend to increase.

[0054] Here, the cold-rolled material after the annealing step [step 5] may be subjected to the cold working step [step 4] and the annealing step [step 5] one or more times. For example, the cold-rolled material after the annealing step [step 5] may be subjected to a second cold working step and annealing step. This allows the copper alloy material to be formed into a plate, bar, strip, or wire having a desired shape, and coarse crystal grains are less likely to be formed, so that a copper alloy material exhibiting desired characteristics in volume resistivity, temperature coefficient of resistance, and thermoelectric power against copper can be obtained.

[0055] [8] Uses of Copper Alloy Material The copper alloy material of the present invention can be in the form of a sheet material or a bar material, or a strip material such as a ribbon material, or a wire material such as a rectangular wire material or a round wire material, and is extremely useful as a resistor material used in resistors, for example, shunt resistors and chip resistors. That is, the resistor material is preferably made of the above-mentioned copper alloy material. Furthermore, resistors such as shunt resistors or chip resistors preferably have a resistor material made of the above-mentioned copper alloy material. Furthermore, since the copper alloy material of the present invention has a relatively high resistance value, it is also suitable as a heater material used in heater elements, for example, heater wires. That is, the heater material is preferably made of the above-mentioned copper alloy material. Furthermore, heater elements such as heater wires preferably have a heater material made of the above-mentioned copper alloy material.

[0056] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, but includes all aspects encompassed by the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention.

[0057] Next, in order to further clarify the effects of the present invention, examples of the present invention and comparative examples will be described, but the present invention is not limited to these examples.

[0058] (Inventive Examples 1 to 13, 19 and Comparative Examples 1 to 5) A casting step [Step 1] was performed in which a copper alloy material having the alloy composition shown in Table 1 was melted and cast to obtain an ingot having a thickness of 30 mm. This ingot was then subjected to a homogenization heat treatment step [Step 2] in which heat treatment was performed at a heating temperature of 800°C for a holding time of 5 hours, and then to a hot working step [Step 3] in which the ingot was rolled along the longitudinal direction at a temperature of 800°C so that the total working ratio was 67%, to obtain a hot-rolled material having a thickness of 10 mm. Thereafter, the ingot was cooled to room temperature by water cooling, and then face-milled to remove the oxide film formed on the surface.

[0059] Next, the hot-rolled material was subjected to a cold-working process [Step 4] in which it was rolled in the longitudinal direction at a total working ratio of 90% to obtain a cold-rolled material with a thickness of 1 mm. Thereafter, the cold-rolled material was subjected to an annealing process [Step 5] in which it was heat-treated by holding it at a heating temperature of 500°C or higher and 750°C or lower for 1 minute.

[0060] After the annealing step [Step 5], a second cold working step [Step 4] was performed in which the material was rolled along the longitudinal direction at a total working ratio of 70%, to obtain a cold-rolled material with a thickness of 0.3 mm. After the second cold working step [Step 4], a second annealing step [Step 5] was performed in which heat treatment was performed at a heating temperature in the range of 500°C to 750°C for a holding time of 1 minute to 2 hours. In this way, copper alloy sheets of Examples 1 to 13 and 19 of the present invention and Comparative Examples 1 to 5 with adjusted crystal grain sizes were produced.

[0061] In Table 1, a horizontal line "-" is entered in the column for components not contained in the alloy composition of the copper alloy material, to indicate that the corresponding component is not contained, or even if it is contained, it is below the detection limit.

[0062] (Invention Examples 14 and 15) A casting step [Step 1] was performed in which a copper alloy material having the alloy composition shown in Table 1 was melted and cast to obtain an ingot having a diameter of 30 mm. This ingot was subjected to a homogenization heat treatment step [Step 2] in which heat treatment was performed at a heating temperature of 800°C for a holding time of 5 hours, and then to a hot working step [Step 3] in which the ingot was extruded at a temperature of 800°C so that the total working ratio was 67%, to obtain a hot-rolled rod having a diameter of 10 mm. Thereafter, the rod was cooled to room temperature by water cooling, and then subjected to facing to remove the oxide film formed on the surface.

[0063] Next, the rod material was subjected to a cold working process [Step 4] in which the rod material was drawn through a circular die to a total working ratio of 80.5%, thereby obtaining a round wire material with a diameter of 1.95 mm. Thereafter, the round wire material was subjected to an annealing process [Step 5] in which the round wire material was heat treated at a heating temperature in the range of 500°C to 750°C for a holding time of 1 minute to 2 hours. In this way, copper alloy wire materials of Examples 14 and 15 of the present invention with adjusted crystal grain sizes were produced.

[0064] (Invention Examples 16 to 18) The rod material obtained in the same manner as in Invention Examples 14 and 15 after the hot working process [Step 3] was drawn through a rectangular die with a curvature radius of 0.1 mm at the four corners to obtain a 96.3% total working ratio. This was followed by a cold working process [Step 4] in which the rod material was drawn to obtain a rectangular wire material having a thickness of 1 mm and a width of 3 mm. The rectangular wire material was then subjected to an annealing process [Step 5] in which the wire material was heat-treated at a heating temperature in the range of 500°C to 750°C for a holding time of 1 minute to 2 hours. In this way, the copper alloy wire material of Invention Examples 16 to 18 with adjusted crystal grain size was produced.

[0065] [Measurement and Evaluation Methods] The copper alloy materials (copper alloy sheets and copper alloy wires) according to the above-mentioned invention examples and comparative examples were used to carry out the following characteristic evaluations. The evaluation conditions for each characteristic were as follows.

[0066] [1] Measurement of average crystal grain size The copper alloy material thus prepared was embedded in resin so that a cross section perpendicular to the stretching direction of the copper alloy material (the longitudinal direction, which is the rolling direction of the sheet material, and the drawing and extrusion directions of the rectangular wire and round wire) was exposed, and then the cross section perpendicular to the stretching direction was polished. Next, the polished specimen was wet-etched using a chromic acid aqueous solution, and the exposed crystal grains were observed in three fields of view at magnifications of 50 to 2000 times depending on the average crystal grain size using a scanning electron microscope (SEM) (Shimadzu Corporation, model number: SSX-550). The crystal grain size was measured using the intercept method of the grain size test method for copper products described in JIS H 0501, and the average crystal grain size was calculated as the average of the crystal grain sizes in the three fields of view. The results are shown in Table 2.

[0067] [2] Measurement of volume resistivity For Examples 1 to 13 and 19 of the present invention and Comparative Examples 1 to 5, in which plate materials were obtained, the obtained 0.3 mm thick plate materials were cut to a width of 10 mm and a length of 300 mm to prepare test materials. For Examples 14 and 15 of the present invention, in which round wire materials were obtained, and Examples 16 to 18 of the present invention, in which rectangular wire materials were obtained, the obtained round wires or rectangular wires were cut to a length of 300 mm to prepare test materials.

[0068] The volume resistivity ρ was measured by measuring the voltage by the four-terminal method in accordance with the method specified in JIS C2525 at a room temperature of 20°C, with a distance between voltage terminals of 200 mm and a measurement current of 100 mA, and the volume resistivity ρ [μΩ cm] was calculated from the obtained value.

[0069] Regarding the measured volume resistivity ρ, when it was 40 μΩ·cm or more and 60 μΩ·cm or less, it was evaluated as "◎" because it had a volume resistivity ρ in an excellent range for a resistance material or a material for a heating element with low energy loss due to heat generation. Furthermore, when the volume resistivity ρ was 25 μΩ·cm or more and less than 40 μΩ·cm, it was evaluated as "○" because it was excellent in terms of low energy loss due to heat generation and had a volume resistivity ρ in a good range for a resistance material or a material for a heating element. Furthermore, when the volume resistivity ρ was more than 60 μΩ·cm and 70 μΩ·cm or less, it was evaluated as "○" because it was excellent as a resistance material or a material for a heating element and had a volume resistivity ρ in a good range for low energy loss due to heat generation. On the other hand, when the volume resistivity ρ was less than 25 μΩ·cm, it was evaluated as "×" because it was poor as a resistance material or a material for a heating element. Furthermore, when the volume resistivity ρ was more than 70 μΩ·cm, it was evaluated as "×" because it was poor because of large energy loss due to heat generation. In this example, the evaluation was conducted with "A" and "B" as pass levels. The results are shown in Table 2.

[0070] [3] Method for measuring thermoelectromotive force (EMF) against copper For Examples 1 to 13 and 19 of the present invention and Comparative Examples 1 to 5, in which plate materials were obtained, the obtained 0.3 mm thick plate materials were cut to a width of 3 mm and a length of 1000 mm to prepare test materials. For Examples 14 and 15 of the present invention, in which round wire materials were obtained, and Examples 16 to 18 of the present invention, in which rectangular wire materials were obtained, the obtained round wires or rectangular wires were cut to a length of 1000 mm to prepare test materials.

[0071] The copper thermoelectromotive force (EMF) of the test material was measured in accordance with JIS C2527. More specifically, as shown in FIG. 2, the copper thermoelectromotive force (EMF) of the test material 1 was measured using a fully annealed pure copper wire with a diameter of 1 mm or less as the standard copper wire 2, and connecting one end of the test material 1 and the standard copper wire 2 to a hot-measuring junction P. １ The other ends of the test material 1 and the standard copper wire 2 are connected to the copper wires 31 and 32, respectively. ２１ , P ２２The electromotive force when the sample was immersed in ice water at 0°C kept cold by a freezing point device 42 was measured by a voltage measuring device 43. The obtained electromotive force was divided by the temperature difference of 80°C to obtain the thermal electromotive force EMF (μV / °C) against copper.

[0072] When the absolute value of the measured thermoelectric power (EMF) against copper was 0.6 μV / °C or less, the absolute value of the thermoelectric power (EMF) against copper was sufficiently small and the material was evaluated as "◎", indicating an excellent resistance material. When the absolute value of the thermoelectric power (EMF) against copper was greater than 0.6 μV / °C and less than 1.0 μV / °C, the absolute value of the thermoelectric power (EMF) against copper was small and the material was evaluated as "◯", indicating a good resistance material. On the other hand, when the absolute value of the thermoelectric power (EMF) against copper was greater than 1.0 μV / °C, the absolute value of the thermoelectric power (EMF) against copper was large and the material was evaluated as "×", indicating a poor resistance material. The results are shown in Table 2.

[0073] [4] Method for measuring temperature coefficient of resistance (TCR) For Examples 1 to 13 and 19 of the present invention and Comparative Examples 1 to 5, in which plate materials were obtained, the obtained 0.3 mm thick plate materials were cut to a width of 10 mm and a length of 300 mm to prepare test materials. For Examples 14 and 15 of the present invention, in which round wire materials were obtained, and Examples 16 to 18 of the present invention, in which rectangular wire materials were obtained, the obtained round wires or rectangular wires were cut to a length of 300 mm to prepare test materials.

[0074] The temperature coefficient of resistance (TCR) was measured by the four-terminal method according to JIS C2526, with the distance between voltage terminals set to 200 mm and the measurement current set to 100 mA. The voltage was measured when the temperature of the test material was heated to 150°C, and the resistance value R at 150°C was calculated from the obtained value. １５０℃ Next, the voltage was measured when the temperature of the test material was cooled to 20°C, and the resistance value R at 20°C was calculated from the obtained value. ２０℃ The resistance value R １５０℃ and R ２０℃ From the value of TCR = {(R １５０℃ [mΩ]-R ２０℃ [mΩ] / R ２０℃ [mΩ]}×{1 / (150[℃]-20[℃])}×10 ６The temperature coefficient of resistance (ppm / °C) was calculated from the formula:

[0075] Regarding the measured temperature coefficient of resistance (TCR), when it was -30 ppm / °C or more and 0 ppm / °C or less, the temperature coefficient of resistance (TCR) was 0 or a negative number and the absolute value was small, which meant that it was excellent and was evaluated as "◎". On the other hand, when the temperature coefficient of resistance (TCR) was less than -30 ppm / °C, the temperature coefficient of resistance (TCR) was a negative number, but the absolute value was large, which meant that it was not excellent and was evaluated as "×". Furthermore, when the temperature coefficient of resistance (TCR) was more than 0 ppm / °C, it was also evaluated as "×" because it was a positive value and was not excellent. The results are shown in Table 2.

[0076] [5] Evaluation of Reliability Furthermore, for Inventive Examples 5, 9, and 19, in order to examine the reliability of the copper alloy material when used for a long period of time as a resistance material, etc., particularly the stability of electrical properties against heat, an accelerated test was performed on the test materials after measuring the volume resistivity in the above-mentioned [2] Measurement of Volume Resistivity, by heating them in a non-oxidizing atmosphere at 450 °C for 10 hours to evaluate the stability of electrical properties against heat. After the accelerated test by heating, the volume resistivity of the test materials was measured using the same method as in the above-mentioned [2] Measurement of Volume Resistivity, and the difference in volume resistivity obtained by subtracting the volume resistivity after heating from the volume resistivity before heating was calculated. Here, when the difference in volume resistivity obtained by subtracting the volume resistivity after heating from the volume resistivity before heating was 0.5 μΩ cm or less, the decrease in volume resistivity due to heating was sufficiently small and the test material was evaluated as "Excellent". This indicated excellent reliability. Furthermore, when the difference in volume resistivity obtained by subtracting the volume resistivity after heating from the volume resistivity before heating was more than 0.5 μΩ cm and 2.0 μΩ cm or less, the decrease in volume resistivity due to heating was small and the reliability was evaluated as "○". When the difference in volume resistivity obtained by subtracting the volume resistivity after heating from the volume resistivity before heating was more than 2.0 μΩ cm, the decrease in volume resistivity due to heating was large and the reliability was evaluated as "△". The results are shown in Table 3.

[0077] [6] Overall Evaluation Among these evaluation results, for the three evaluation results regarding volume resistivity ρ, copper thermoelectromotive force (EMF), and temperature coefficient of resistance (TCR), if all three were evaluated as "◎," the volume resistivity ρ, copper thermoelectromotive force (EMF), and temperature coefficient of resistance (TCR) were all excellent and evaluated as "◎." Furthermore, if one or two of these three evaluation results were evaluated as "◎" and the remaining were evaluated as "○," the volume resistivity ρ, copper thermoelectromotive force (EMF), and temperature coefficient of resistance (TCR) properties were good and evaluated as "○." On the other hand, if any of the three evaluation results regarding volume resistivity ρ, copper thermoelectromotive force (EMF), and temperature coefficient of resistance (TCR) was evaluated as "×," the volume resistivity ρ, copper thermoelectromotive force (EMF), and temperature coefficient of resistance (TCR) properties were insufficient and evaluated as "×." The results are shown in Table 2.

[0078]

[0079]

[0080]

[0081] From the results of Tables 1 and 2, the copper alloy materials of Inventive Examples 1 to 19 had alloy compositions within the appropriate range of the present invention, and the three evaluation results regarding volume resistivity ρ, thermoelectromotive force (EMF) against copper, and temperature coefficient of resistance (TCR) were all evaluated as "◎" or "◯", and the overall evaluation was also evaluated as "◎" or "◯".

[0082] Therefore, all of the copper alloy materials of Inventive Examples 1 to 19 were evaluated as "◎" or "◯" in the comprehensive evaluation, and therefore had a volume resistivity ρ within a desired range, a small absolute value of the thermoelectromotive force (EMF) against copper, and a temperature coefficient of resistance in a wide temperature range from room temperature (e.g., 20°C) to a high temperature (e.g., 150°C) that was either 0 or a negative number with a small absolute value.

[0083] On the other hand, the alloy compositions of all of the copper alloy materials of Comparative Examples 1 to 5 were outside the appropriate range of the present invention. Therefore, the copper alloy materials of Comparative Examples 1 to 5 were evaluated as "x" in at least one of the volume resistivity ρ, thermoelectromotive force (EMF) against copper, and temperature coefficient of resistance (TCR).

[0084] Furthermore, from the reliability evaluation results for Inventive Examples 5, 9, and 19 shown in Table 3, it was found that the copper alloy materials of Inventive Examples 5 and 19, which have an Fe content of 0.15 mass% or less, showed a change in volume resistivity before and after heating that was half or less of that of Inventive Example 9, which had an Fe content of 0.30 mass% and was evaluated as "△" in reliability, and therefore had improved stability of electrical properties against heat, etc., and were therefore evaluated as "◎" or "◯" in reliability evaluation results. Furthermore, it was found that the copper alloy material of Inventive Example 5, which does not contain Fe, showed almost no change in volume resistivity before and after heating, and particularly improved stability of electrical properties against heat, etc., and therefore was evaluated as "◎" in reliability evaluation results.

[0085] 1 Test material 2 Standard copper wire 31, 32 Copper wire 41 Constant temperature chamber 42 Freezing point device 43 Voltage measuring device P １ Temperature measurement contact P ２１ , P ２２ Reference Junction

Claims

1. A copper alloy material having an alloy composition containing Mn: 7.0 mass% or more and 17.0 mass% or less, Ni: 0.1 mass% or more and 3.0 mass% or less, and Al: 1.0 mass% or more and 5.0 mass% or less, with the remainder being Cu and unavoidable impurities.

2. The copper alloy material according to claim 1, wherein the Mn content in the alloy composition is 7.0 mass% or more and 14.0 mass% or less.

3. The copper alloy material according to claim 1, wherein the alloy composition further contains Co: 0.01 mass % or more and 1.30 mass % or less.

4. The copper alloy material according to claim 3, wherein the alloy composition further contains Fe: 0.01 mass % or more and 0.30 mass % or less.

5. The copper alloy material according to any one of claims 1 to 4, wherein the alloy composition further contains one or more components selected from the group consisting of Sn: 0.01 mass% or more and 2.00 mass% or less, Zn: 0.01 mass% or more and 3.00 mass% or less, Cr: 0.01 mass% or more and 0.50 mass% or less, Ag: 0.01 mass% or more and 0.50 mass% or less, Mg: 0.01 mass% or more and 0.50 mass% or less, Si: 0.01 mass% or more and 0.50 mass% or less, and P: 0.01 mass% or more and 0.50 mass% or less.

6. The copper alloy material according to claim 1, having a metal structure with an average crystal grain size of 40 μm or less.

7. A resistance material for resistors, comprising the copper alloy material according to claim 1.

8. A resistor comprising the resistive material according to claim 7.

9. A material for a heating element, comprising the copper alloy material according to claim 1.

10. A heating element comprising the material for heating elements according to claim 9.

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