Copper alloy sheet

Abstract

This copper alloy sheet is characterized in that: Cr is contained therein within the range from 0.05 mass% to 1.0 mass%; Zr is contained therein within the range from 0.01 mass% to 0.5 mass%; when the TD surface is observed, the ratio Gr / Gn of the maximum crystal length Gr in the rolling direction to the maximum crystal length Gn in the sheet thickness direction is 5 or more; the conductivity IGW in the rolling direction and the conductivity IBW in the sheet width direction are both 70% IACS or more; the difference (IGW – IBW) between the conductivity IGW in the rolling direction and the conductivity IBW in the sheet width direction exceeds 0.1% IACS; and the tensile strength in the rolling direction is 500 MPa or more.

Description

copper alloy plate

[0001] The present invention relates to a copper alloy sheet suitable as a material for electrical and electronic device components such as terminals, connectors, relays, switches, sockets, bus bars, lead frames, and heat sinks. This application claims priority based on Japanese Patent Application No. 2023-204885 filed on December 4, 2023, the contents of which are incorporated herein by reference.

[0002] Conventionally, copper alloy sheets, which have excellent electrical conductivity, have been used as materials for electronic and electrical device components such as terminals, connectors, relays, switches, sockets, bus bars, lead frames, and heat sinks. Conventional Cu—Cr-based alloys and Cu—Zr-based alloys have been widely used as copper alloy sheets for the above-mentioned various applications. Cu—Cr-based alloys and Cu—Zr-based alloys are precipitation-strengthened alloys that have improved strength by precipitating intermetallic compounds containing Cr or intermetallic compounds containing Zr in the copper matrix, and are widely used in a variety of applications due to their excellent strength, electrical conductivity, and thermal conductivity.

[0003] In recent years, with the expansion of applications for Cu-Cr alloys and Cu-Zr alloys and the trend toward lighter, thinner, and smaller electrical and electronic devices, there has been a demand for Cu-Cr alloys and Cu-Zr alloys with even higher strength, higher electrical conductivity, and better thermal conductivity. For example, in Patent Document 1, strength and other properties are improved by controlling the area ratio of particle groups with different crystal grain sizes.

[0004] Japanese Patent Application Publication No. 2005-298931 (A)

[0005] Among electrical and electronic components, those for which current flows in a specific direction, such as bus bars, require electrical conductivity, particularly in the longitudinal direction. However, no conventional Cu—Cr-based alloys or Cu—Zr-based alloys have been proposed in which the anisotropy of electrical conductivity has been fully considered. Patent Document 1 aims to improve properties such as strength by suppressing the increase in the anisotropy of mechanical properties, but does not pay attention to the anisotropy of electrical conductivity.

[0006] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a copper alloy sheet which is excellent in strength and electrical conductivity, has anisotropic electrical conductivity, and is particularly suitable as a material for parts of electric and electronic devices in which current flows in a specific direction.

[0007] In order to solve the above problems, a copper alloy sheet according to an aspect 1 of the present invention contains Cr in a range of 0.05 mass% or more and 1.0 mass% or less, Zr in a range of 0.01 mass% or more and 0.5 mass% or less, and when observing the TD surface, the ratio Gr / Gn of the maximum crystal length Gr in the rolling direction to the maximum crystal length Gn in the sheet thickness direction is 5 or more, and the electrical conductivity I in the rolling direction is ＧＷ and the conductivity in the plate width direction I ＢＷ are both 70% IACS or more, and the electrical conductivity I ＧＷ and the conductivity in the plate width direction I ＢＷ Difference I ＧＷ -I ＢＷ is more than 0.1% IACS, and the tensile strength in the rolling direction is 500 MPa or more.

[0008] According to the copper alloy sheet of the first aspect of the present invention, Cr is contained in the range of 0.05 mass % or more and 1.0 mass % or less, Zr is contained in the range of 0.01 mass % or more and 0.5 mass % or less, and the electrical conductivity in the rolling direction I ＧＷ and the conductivity in the plate width direction I ＢＷ Both are 70% IACS or more, and the tensile strength in the rolling direction is 500 MPa or more, so it has excellent strength and electrical conductivity. Therefore, it is possible to reduce the amount of heat generated when current is applied, and to make parts smaller and thinner. When observing the TD surface, it is found that the ratio Gr / Gn of the maximum crystal length Gr in the rolling direction to the maximum crystal length Gn in the plate thickness direction is 5 or more, and the electrical conductivity in the rolling direction I ＧＷ and the conductivity in the plate width direction I ＢＷ Difference I ＧＷ -I ＢＷ Since the conductivity exceeds 0.1% IACS, the steel has anisotropy in conductivity, with the conductivity being particularly high in the rolling direction, making it particularly suitable as a material for parts of electrical and electronic equipment that require current to flow in a specific direction.

[0009] The copper alloy sheet of Aspect 2 of the present invention is characterized in that, when the TD surface is observed in the copper alloy sheet of Aspect 1 of the present invention, the maximum crystal length Gr in the rolling direction is 8 μm or more and the maximum crystal length Gn in the sheet thickness direction is 4 μm or less. According to the copper alloy sheet of Aspect 2 of the present invention, since the maximum crystal length Gr in the rolling direction is 8 μm or more and the maximum crystal length Gn in the sheet thickness direction is 4 μm or less, the copper alloy sheet has a crystalline structure elongated in the rolling direction, and the anisotropy of the electrical conductivity can be further improved so as to further increase the electrical conductivity in the rolling direction.

[0010] The copper alloy sheet of Aspect 3 of the present invention is characterized in that, in the copper alloy sheet of Aspect 1 or Aspect 2 of the present invention, the Vickers hardness is 180 HV or more and the heat-resistant temperature at which the Vickers hardness becomes 80% of the initial Vickers hardness when heat-treated for 1 hour is 500°C or more. According to the copper alloy sheet of Aspect 3 of the present invention, the Vickers hardness is 180 HV or more and the heat-resistant temperature at which the Vickers hardness becomes 80% of the initial Vickers hardness when heat-treated for 1 hour is 500°C or more, so that the strength and heat resistance are particularly excellent.

[0011] A copper alloy sheet according to a fourth aspect of the present invention is the copper alloy sheet according to any one of the first to third aspects of the present invention, characterized in that it contains one or more additive elements selected from the group consisting of Ti, Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn, and B, and the total content of the additive elements is 0.1 mass% or less. According to the copper alloy according to the fourth aspect of the present invention, since it contains one or more additive elements selected from the group consisting of Ti, Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn, and B, the strength can be further improved. Furthermore, since the total content of the additive elements is 0.1 mass% or less, a decrease in electrical conductivity can be suppressed.

[0012] The copper alloy sheet of Aspect 5 of the present invention is characterized in that it mainly contains Cr-containing precipitates having an equivalent circle diameter of 50 nm or less and Zr-containing precipitates having an equivalent circle diameter of 1 μm or less in the copper alloy sheet of any one of Aspects 1 to 4 of the present invention. According to the copper alloy sheet of Aspect 5 of the present invention, since the copper alloy sheet mainly contains Cr-containing precipitates having an equivalent circle diameter of 50 nm or less and Zr-containing precipitates having an equivalent circle diameter of 1 μm or less, it is possible to sufficiently improve strength by precipitation strengthening and obtain high electrical conductivity.

[0013] It is possible to provide a copper alloy sheet that is excellent in strength and conductivity, has anisotropic conductivity, and is particularly suitable as a material for parts of electric and electronic devices that require current to flow in a specific direction.

[0014] 1 is a flow diagram of a method for producing a copper alloy sheet according to an embodiment of the present invention.

[0015] A copper alloy sheet according to one embodiment of the present invention will be described below. The copper alloy sheet according to this embodiment contains Cr in the range of 0.05% by mass to 1.0% by mass, Zr in the range of 0.01% by mass to 0.5% by mass, and the remainder is Cu and inevitable impurities. In addition, in the copper alloy sheet according to this embodiment, when the TD surface is observed, the ratio Gr / Gn of the maximum crystal length Gr in the rolling direction to the maximum crystal length Gn in the sheet thickness direction is 5 or more. Here, the TD surface refers to a surface perpendicular to the rolling direction (RD surface) and the rolled surface (ND surface).

[0016] In the copper alloy sheet of this embodiment, the electrical conductivity I ＧＷ and the conductivity in the plate width direction I ＢＷ are both 70% IACS or more, and the electrical conductivity I ＧＷ and the conductivity in the plate width direction I ＢＷ Difference I ＧＷ -I ＢＷ exceeds 0.1% IACS. That is, the electrical conductivity I ＧＷ is the conductivity in the plate width direction I ＢＷ The copper alloy sheet according to the present embodiment has anisotropic electrical conductivity and has a tensile strength of 500 MPa or more in the rolling direction.

[0017] Here, the copper alloy plate of this embodiment contains one or more additive elements selected from Ti, Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn, and B, and the total content of these additive elements may be 0.1 mass% or less.

[0018] In addition, in the copper alloy sheet of this embodiment, when the TD surface is observed, it is preferable that the maximum crystal length Gr in the rolling direction is 8 μm or more and the maximum crystal length Gn in the sheet thickness direction is 4 μm or less. Furthermore, in the copper alloy sheet of this embodiment, it is preferable that precipitates containing Cr and having an equivalent circle diameter of 50 nm or less and precipitates containing Zr and having an equivalent circle diameter of 1 μm or less are mainly present. Furthermore, in the copper alloy sheet of this embodiment, it is preferable that the Vickers hardness is 180 Hv or more. Furthermore, it is preferable that the temperature (heat resistance temperature) at which the Vickers hardness becomes 80% of the initial value when heat-treated for 1 hour is 500 ° C. or more.

[0019] The reasons for specifying the component composition, crystalline structure, precipitates, electrical conductivity, tensile strength, Vickers hardness, and heat-resistant temperature of the copper alloy sheet of this embodiment as described above will be explained below.

[0020] (Cr) Cr is an element that has the effect of improving strength without reducing electrical conductivity by finely precipitating Cr-based precipitates (e.g., Cu—Cr) within the crystal grains of the matrix through aging treatment. Here, if the Cr content is less than 0.05 mass%, the effects of improving strength and Vickers hardness may not be sufficiently obtained. On the other hand, if the Cr content exceeds 1.0 mass%, relatively coarse Cr crystals may be generated, which may cause defects. For this reason, in this embodiment, the Cr content is set to a range of 0.05 mass% or more and 1.0 mass% or less. The Cr content is preferably 0.10 mass% or more, more preferably 0.15 mass% or more, and even more preferably 0.20 mass% or more. The Cr content is preferably 0.80 mass% or less, more preferably 0.60 mass% or less, and even more preferably 0.40 mass% or less.

[0021] (Zr) Zr is a Zr-based precipitate (e.g., Cu) formed in the crystal grains of the matrix by aging treatment. ５ Zr is an element that has the effect of improving strength without reducing electrical conductivity by finely precipitating Zr. Here, if the Zr content is less than 0.01 mass%, the effects of improving strength and Vickers hardness may not be sufficiently obtained. On the other hand, if the Zr content exceeds 0.5 mass%, relatively coarse Zr crystals may be generated, which may cause defects. For this reason, in this embodiment, the Zr content is set to a range of 0.01 mass% or more and 0.5 mass% or less. The Zr content is preferably 0.03 mass% or more, and more preferably 0.06 mass% or more. Furthermore, the Zr content is preferably 0.4 mass% or less, and more preferably 0.2 mass% or less.

[0022] (Additive Elements) One or more additive elements selected from Ti, Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn, and B have the effect of improving the strength of the copper alloy sheet. Therefore, these additive elements may be included to further improve strength. However, since these additive elements reduce electrical conductivity, it is preferable to limit the total content of the additive elements to 0.1 mass% or less. Note that the total content of one or more additive elements selected from Ti, Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn, and B is more preferably 0.08 mass% or less, and even more preferably 0.05 mass% or less.

[0023] (Ratio Gr / Gn of Maximum Crystal Length Gr in the Rolling Direction to Maximum Crystal Length Gn in the Sheet Thickness Direction) When observing the TD surface of the copper alloy sheet of this embodiment, if the ratio Gr / Gn of the maximum crystal length Gr in the rolling direction to the maximum crystal length Gn in the sheet thickness direction is large, the crystals will have a shape elongated in the rolling direction, and the precipitates will also be distributed along the rolling direction. This results in anisotropy in electrical conductivity. For this reason, in this embodiment, the ratio Gr / Gn of the maximum crystal length Gr in the rolling direction to the maximum crystal length Gn in the sheet thickness direction is specified to be 5 or more. Note that the ratio Gr / Gn of the maximum crystal length Gr in the rolling direction to the maximum crystal length Gn in the sheet thickness direction is preferably 6 or more, more preferably 7 or more.

[0024] (Maximum crystal length Gr in the rolling direction, maximum crystal length Gn in the thickness direction) When observing the TD surface of the copper alloy sheet of this embodiment, if the maximum crystal length Gr in the rolling direction is 8 μm or more and the maximum crystal length Gn in the thickness direction is 4 μm or less, the crystals extend in the rolling direction to form a relatively fine crystal structure, thereby further improving the anisotropy of electrical conductivity and further improving the strength. The maximum crystal length Gr in the rolling direction is more preferably 9 μm or more, and even more preferably 10 μm or more. The maximum crystal length Gn in the thickness direction is more preferably 3 μm or less, and even more preferably 2 μm or less.

[0025] (Precipitates containing Cr and precipitates containing Zr) In the copper alloy sheet of this embodiment, when precipitates containing Cr and having an equivalent circle diameter of 50 nm or less and precipitates containing Zr and having an equivalent circle diameter of 1 μm or less are mainly present, the strength is further improved by precipitation strengthening by these precipitates. Note that "mainly present" specifically means that the number ratio of precipitates containing Cr and having an equivalent circle diameter of 50 nm or less and precipitates containing Zr and having an equivalent circle diameter of 1 μm or less to the total number of precipitates observed in the observation field of view is 60% or more.

[0026] (Conductivity in the rolling direction I ＧＷ , conductivity in the plate width direction I ＢＷIn electrical and electronic equipment components, excellent electrical conductivity is required to suppress heat generation during current flow. For this reason, the copper alloy sheet of this embodiment has a rolling direction electrical conductivity I ＧＷ and the conductivity in the plate width direction I ＢＷ The electrical conductivity in the rolling direction I ＧＷ , conductivity in the plate width direction I ＢＷ is preferably 73% IACS or more, and more preferably 76% IACS or more.

[0027] (Conductivity in the rolling direction I ＧＷ and the conductivity in the plate width direction I ＢＷ Difference I ＧＷ -I ＢＷ In the copper alloy sheet of this embodiment, the electrical conductivity I in the rolling direction ＧＷ and the conductivity in the plate width direction I ＢＷ Difference I ＧＷ -I ＢＷ The electrical conductivity I in the rolling direction is anisotropic, so that the electrical conductivity I in the rolling direction exceeds 0.1% IACS. This makes it possible to suppress heat generation when electricity is passed through electrical and electronic equipment components that pass electricity in a specific direction. ＧＷ and the conductivity in the plate width direction I ＢＷ Difference I ＧＷ -I ＢＷ is preferably 0.2% IACS or more, and more preferably 0.4% IACS or more.

[0028] (Tensile strength) In the copper alloy sheet of this embodiment, by increasing the strength, it is possible to reduce the weight and thickness of parts for electric and electronic devices. For this reason, in this embodiment, the tensile strength in the rolling direction of the copper alloy sheet is specified to be 500 MPa or more. The tensile strength in the rolling direction is preferably 550 MPa or more, and more preferably 600 MPa or more.

[0029] (Vickers hardness) In the copper alloy sheet of this embodiment, if the Vickers hardness is sufficiently high, the copper alloy sheet will not easily deform during use or handling, and it will be possible to further reduce the weight and thickness of electrical and electronic equipment components. Therefore, in this embodiment, the Vickers hardness of the copper alloy sheet is preferably 180 HV or more. The Vickers hardness of the copper alloy sheet of this embodiment is more preferably 190 HV or more, and even more preferably 200 HV or more.

[0030] (Heat resistance temperature) Heat resistance may be required depending on the use of parts for electric and electronic devices. Therefore, in the copper alloy sheet of this embodiment, the heat resistance temperature at which the Vickers hardness becomes 80% of the initial hardness when heat-treated at a specific temperature for 1 hour is preferably 500°C or higher. The heat resistance temperature of the copper alloy sheet of this embodiment is more preferably 520°C or higher, and even more preferably 540°C or higher.

[0031] Next, an example of a method for producing a copper alloy sheet according to this embodiment will be described with reference to the flow chart shown in FIG.

[0032] (Melting and Casting Step S01) First, the aforementioned elements are added to the molten copper obtained by melting a copper raw material to adjust the composition, thereby producing a molten copper alloy. The various elements can be added using simple elements or master alloys. Raw materials containing the aforementioned elements may also be melted together with the copper raw material. Recycled or scrap materials of this alloy may also be used. Here, the molten copper is preferably so-called 4NC Cu, which has a purity of 99.99% by mass or more, or so-called 5NC Cu, which has a purity of 99.999% by mass or more. The molten copper alloy with the adjusted composition is then poured into a mold to produce an ingot. When considering mass production, it is preferable to use a continuous casting method or a semi-continuous casting method.

[0033] (Homogenization step S02) Next, a heat treatment is performed to homogenize the obtained ingot. The ingot is preferably held at 850°C or higher and 1050°C or lower for 1 hour or longer. There is no upper limit to the holding time in the homogenization step S02, but considering costs and manufacturing efficiency, it is preferably 24 hours or shorter. There is also no particular limit to the cooling rate in the homogenization step S02, and air cooling or water cooling may be used.

[0034] (Hot working step S03) Next, hot working is performed. This hot working step S03 may also serve as the homogenization step S02. After holding at 850°C or higher and 1050°C or lower for at least one hour, hot working is performed at 600°C or higher and 1050°C or lower. When the temperature drops below 600°C, the temperature is raised again, and when it reaches 800°C, hot working is performed again. This process is repeated multiple times until the working rate reaches 90% or higher, and then the material temperature is rapidly reduced by water cooling.

[0035] (Cold working step S04) After the hot working step S03, cold working is performed. The working ratio at this time is not particularly limited, but the total working ratio of the cold working performed after the hot working is preferably 90% or more.

[0036] (Heat Treatment Step S05) After the hot working step S03, a heat treatment is carried out in which the temperature is held at 200°C or higher and 600°C or lower for 1 minute or more. This heat treatment step S05 serves to relieve strain and perform aging precipitation. Heat treatment at a high temperature above 600°C is undesirable because it destroys the desired crystalline structure due to recrystallization. In the case of aging treatment, it is preferable to hold the temperature at 400°C or higher and 600°C or lower for 1 hour or more. The heat treatment step S05 and the cold working step S04 can be freely combined without any problems.

[0037] The copper alloy sheet of this embodiment is manufactured through the above-mentioned steps. In this embodiment, the temperature increase and processing are repeated multiple times in the hot working step S03, and the processed structure is continued until the final step, thereby improving the electrical conductivity in a specific direction and achieving high strength. By repeating the temperature increase and processing multiple times during hot rolling, crystalline substances and precipitates that could not be solid-dissolved during homogenization are refined by elongation or shear in the rolling direction, forming a metal structure in which the crystalline substances and precipitates are likely to be continuously arranged, resulting in anisotropic electrical conductivity. Furthermore, some of the crystalline substances and precipitates that could not be solid-dissolved in the homogenization step S02 are re-dissolved, and precipitation is promoted by the subsequent heat treatment step S05, thereby promoting high strength due to the fine precipitates.

[0038] According to the copper alloy sheet of this embodiment having the above-described configuration, Cr is contained in the range of 0.05 mass % or more and 1.0 mass % or less, Zr is contained in the range of 0.01 mass % or more and 0.5 mass % or less, and the electrical conductivity in the rolling direction I ＧＷ and the conductivity in the plate width direction I ＢＷ The tensile strength in the rolling direction is 500 MPa or more, which means that the strength and electrical conductivity are excellent. This allows for a reduction in the amount of heat generated when current is applied, and allows for the miniaturization and thinning of electrical and electronic equipment parts.

[0039] When the TD surface is observed, the ratio Gr / Gn of the maximum crystal length Gr in the rolling direction to the maximum crystal length Gn in the thickness direction is 5 or more, and the electrical conductivity I ＧＷ and the conductivity in the plate width direction I ＢＷ Difference I ＧＷ -I ＢＷ Since the conductivity exceeds 0.1% IACS, the steel has anisotropy in conductivity, with the conductivity being particularly high in the rolling direction, making it particularly suitable as a material for parts of electrical and electronic equipment that require current to flow in a specific direction.

[0040] In the copper alloy sheet of the present embodiment, when the maximum crystal length Gr in the rolling direction is 8 μm or more and the maximum crystal length Gn in the sheet thickness direction is 4 μm or less when the TD surface is observed, the crystal structure is elongated in the rolling direction, and the anisotropy of the conductivity can be further improved so that the conductivity in the rolling direction is further increased.

[0041] In the copper alloy sheet of this embodiment, when the Vickers hardness is 180 HV or more, the copper alloy sheet does not easily deform during use or handling, and it is possible to further reduce the weight and thickness of electrical and electronic equipment parts. Furthermore, in the copper alloy sheet of this embodiment, when the heat-resistant temperature at which the Vickers hardness becomes 80% of the initial Vickers hardness when heat-treated for 1 hour is 500°C or more, the copper alloy sheet has sufficient heat resistance and can be used as a material for electrical and electronic equipment parts used in high-temperature environments.

[0042] In the copper alloy plate of the present embodiment, when one or more additive elements selected from Ti, Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn, and B are contained and the total content of the additive elements is 0.1 mass% or less, the strength can be further improved while maintaining high electrical conductivity.

[0043] In the copper alloy plate of the present embodiment, when precipitates containing Cr and having an equivalent circle diameter of 50 nm or less and precipitates containing Zr and having an equivalent circle diameter of 1 μm or less are mainly present, the strength can be sufficiently improved by precipitation strengthening, and high electrical conductivity can be obtained.

[0044] Although the copper alloy and the part for electronic / electrical equipment according to the embodiment of the present invention have been described above, the present invention is not limited thereto and can be appropriately modified within the scope of the technical idea of ​​the invention. In the above embodiment, an example of a method for manufacturing a copper alloy has been described, but the method for manufacturing a copper alloy is not limited to that described in the embodiment and an existing manufacturing method may be appropriately selected for manufacturing the copper alloy.

[0045] The results of confirmation experiments conducted to confirm the effects of the present invention will be described below.

[0046] A copper raw material consisting of oxygen-free copper with a purity of 99.99% by mass was prepared and placed in a high-purity graphite crucible. It was then high-frequency melted in an atmospheric furnace containing an Ar gas atmosphere. Various additive elements were added to the resulting molten copper to adjust the composition shown in Table 1. The molten copper was then poured into a water-cooled copper mold to produce an ingot. The size of the ingot was approximately 50 mm thick, 80 mm wide, and 150 mm long.

[0047] The resulting ingot was subjected to a heat treatment process in which it was heated to 1000 to 1050 ° C for 4 hours in an Ar gas atmosphere for homogenization and solution treatment, and then hot rolling was performed. In hot rolling, the material temperature was measured each time rolling was performed at a temperature of 600 ° C or higher and 1050 ° C or lower, and the temperature was increased again when the temperature was below 600 ° C. After the material temperature reached 800 ° C or higher, rolling was performed again. This was repeated multiple times, and after the processing rate reached 90% or higher, the material temperature was rapidly reduced by water cooling, completing the hot rolling process and producing plates with a thickness of 2 to 4 mm. Table 1 lists the number of times hot processing was repeated.

[0048] As an intermediate processing step, 90 to 95% cold rolling was performed, followed by intermediate heat treatment at 400 to 600°C for 2 to 8 hours. The heat treatment temperatures are shown in Table 1. Next, as a finishing processing step, cold rolling was performed to produce strip material with a thickness of approximately 0.1 mm. The obtained strip material was then heat treated at 200°C for 1 minute to produce strip material for property evaluation.

[0049] The copper alloy sheets of the present invention and comparative examples obtained as described above were evaluated as follows.

[0050] (Alloy composition) Measurement samples were taken from the resulting ingots and subjected to component analysis. Cr and Zr were measured using an inductively coupled plasma optical emission spectrometer (ICPAES). Other elements were measured using a glow discharge mass spectrometer (GD-MS).

[0051] (Maximum crystal length Gr in the rolling direction and maximum crystal length Gn in the plate thickness direction) A test piece with a width of 20 mm x length of 20 mm was cut out from the obtained copper alloy plate, and the surface perpendicular to the width direction of rolling, i.e., the TD surface (Transverse Direction), was used as the observation surface and embedded in resin to obtain an observation sample. The crystal grain size was measured using an SEM-EBSD (Electron Backscatter Diffraction Patterns) measurement device as follows. The surface perpendicular to the width direction of rolling, i.e., the TD surface (Transverse Direction), was used as the observation surface, and mechanical polishing was performed using waterproof abrasive paper and diamond abrasive grains. Next, finish polishing was performed using a colloidal silica solution to obtain a measurement sample. Thereafter, an EBSD measurement device (SU7000 manufactured by Hitachi High-Tech Corporation, APEX manufactured by EDAX / TSL (now AMETEK)) and analysis software (OIM Data Analysis ver. 8.6.109 manufactured by EDAX / TSL (now AMETEK)) were used to measure the EBSD at 1000 μm. ２ The observation surface was measured using the EBSD method at 0.07 μm measurement intervals over the above measurement area. The measurement results were analyzed using data analysis software OIM to obtain the CI value for each measurement point. Except for measurement points with a CI value of 0.1 or less, the misorientation of each crystal grain was analyzed using data analysis software OIM. The boundaries between adjacent measurement points where the misorientation between the measurement points was 5° or more were defined as grain boundaries. A grain boundary map was created from the results of the obtained orientation analysis. In accordance with the cutting method of JIS H 0501, 10 or more lines of predetermined length were drawn on the grain boundary map, and the maximum grain cut length was determined, which were defined as the maximum crystal length Gr in the rolling direction and the maximum crystal length Gn in the thickness direction.

[0052] (Precipitates containing Cr and having an equivalent circle diameter of 50 nm or less, and precipitates containing Zr and having an equivalent circle diameter of 1 μm or less were mainly present.) The above-mentioned measurement sample was used to observe the precipitates as follows. Precipitates smaller than 100 nm were observed using a high-resolution scanning transmission electron microscope (S / TEM), and the precipitate composition was confirmed by an energy dispersive X-ray spectrometer (EDS: Energy Dispersive X-ray Spectroscope). Precipitates larger than 100 nm were observed using a scanning electron microscope (SEM), and the precipitate composition was confirmed by EDS. S / TEM was used for 10,000 nm. ２ Above field of view, magnification × 376k, SEM is 100 μm ２ At least five visual fields were observed under the above conditions of visual field and magnification × 10k, and the longest shear length of the precipitates was taken as the particle size of the precipitates. The percentage of the number of Cr-containing precipitates with an equivalent circle diameter of 50 nm or less was calculated using the numerator "number of Cr-containing precipitates with an equivalent circle diameter of 50 nm or less (A)" and the denominator "number of precipitates less than 100 nm observed by S / TEM (X)." The percentage of the number of Zr-containing precipitates with an equivalent circle diameter of 1 μm or less was calculated using the numerator "Zr-containing precipitates with an equivalent circle diameter of 1 μm or less (B)" and the denominator "number of precipitates of 100 nm or more observed by SEM (Y)." Furthermore, when both (A / X) × 100, which is the number ratio (%) of the above-mentioned Cr-containing precipitates, and (B / Y) × 100, which is the number ratio (%) of the above-mentioned Zr-containing precipitates, were 60% or more, the evaluation was made as "Good", and when either or both were less than 60%, the evaluation was made as "Poor".

[0053] (Electrical Conductivity) Test pieces measuring 10 mm in width and 100 mm in length were taken from the obtained copper alloy sheets, and the electrical resistance was determined by a four-terminal method. A test piece having a length of 100 mm in the rolling direction and a test piece having a length of 100 mm in the sheet width direction were taken, and the electrical resistance in the rolling direction and the sheet width direction were measured, respectively. The dimensions of the test pieces were also measured using a micrometer, and the volume of the test pieces was calculated. The electrical conductivity I in the rolling direction was calculated from the measured electrical resistivity and the calculated volume. ＧＷ and the conductivity in the plate width direction I ＢＷwas measured.

[0054] (Tensile strength) No. 13B test pieces were taken from the obtained copper alloy sheets, and the tensile strength was measured in accordance with JIS Z 2241. The test pieces were taken so that the tensile direction was parallel to the rolling direction.

[0055] (Vickers Hardness) Vickers hardness was measured at a test load of 0.98 N in accordance with the micro Vickers hardness test method specified in JIS Z 2244.

[0056] (Heat resistance evaluation) The heat resistance temperature was measured in accordance with JCBA T325: 2013 of the Japan Copper and Brass Association. The Vickers hardness of the sample before the heat resistance test was defined as HvRT. The heat resistance test involved heat treatment at 10°C intervals between 450 and 650°C for 1 hour, followed by rapid cooling. The temperature at which the measured Vickers hardness was 80% of the Vickers hardness at HvRT was determined as the heat resistance temperature.

[0057]

[0058]

[0059]

[0060] In Comparative Example 1, the electrical conductivity I ＧＷ and the conductivity in the plate width direction I ＢＷ Difference I ＧＷ -I ＢＷ The electrical conductivity in the rolling direction was low at 0.1% IACS, and the anisotropy was insufficient. Furthermore, the strength was low at 492 MPa. In Comparative Example 2, the ratio Gr / Gn of the maximum crystal length Gr in the rolling direction to the maximum crystal length Gn in the thickness direction was low at 2.2, and the electrical conductivity in the rolling direction I ＧＷ and the conductivity in the plate width direction I ＢＷ Difference I ＧＷ -I ＢＷ No anisotropy was observed in the conductivity.

[0061] In Comparative Example 3, the electrical conductivity I ＧＷ and the conductivity in the plate width direction I ＢＷ Difference I ＧＷ -I ＢＷIn Comparative Example 4, the electrical conductivity I in the rolling direction was small at 0.1% IACS, and the anisotropy of the electrical conductivity was insufficient. ＧＷ and the conductivity in the plate width direction I ＢＷ Difference I ＧＷ -I ＢＷ The anisotropy was as small as 0.1% IACS, and the anisotropy was not sufficient for electrical conductivity.

[0062] In contrast, in Examples 1 to 11 of the present invention, the electrical conductivity I ＧＷ and the conductivity in the plate width direction I ＢＷ Difference I ＧＷ -I ＢＷ It was confirmed that the material has sufficient anisotropy in conductivity, making it particularly suitable as a material for parts in electrical and electronic devices that require current to flow in a specific direction.

[0063] It is possible to provide a copper alloy sheet that is excellent in strength and conductivity, has anisotropic conductivity, and is particularly suitable as a material for parts of electric and electronic devices in which current flows in a specific direction.

Claims

1. The steel contains Cr in the range of 0.05 mass% or more and 1.0 mass% or less, and Zr in the range of 0.01 mass% or more and 0.5 mass% or less. When observing the TD surface, the ratio Gr / Gn of the maximum crystal length Gr in the rolling direction to the maximum crystal length Gn in the sheet thickness direction is 5 or more, and the electrical conductivity I in the rolling direction is ＧＷ and the electrical conductivity I in the plate width direction ＢＷ Both are 70% IACS or more, and the electrical conductivity I ＧＷ and the electrical conductivity I in the plate width direction ＢＷ Difference I ＧＷ -I ＢＷ A copper alloy sheet having a tensile strength in the rolling direction of 500 MPa or more.

2. A copper alloy sheet according to claim 1, characterized in that, when observed on the TD surface, the maximum crystal length Gr in the rolling direction is 8 μm or more and the maximum crystal length Gn in the sheet thickness direction is 4 μm or less.

3. A copper alloy sheet according to claim 1 or 2, characterized in that it has a Vickers hardness of 180 HV or more and a heat-resistant temperature at which it becomes 80% of its initial Vickers hardness when heat-treated for one hour is 500°C or more.

4. A copper alloy sheet according to claim 1 or 2, characterized in that it contains one or more additive elements selected from the group consisting of Ti, Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn and B, and the total content of the additive elements is 0.1 mass% or less.

5. A copper alloy sheet according to claim 1 or 2, characterized in that it mainly contains precipitates containing Cr and having an equivalent circle diameter of 50 nm or less, and precipitates containing Zr and having an equivalent circle diameter of 1 μm or less.

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