Copper alloy, plastically processed copper alloy, components for electronic and electrical equipment, terminals, bus bars, lead frames, heat dissipation substrates

Abstract

One embodiment of this copper alloy contains more than 10 massppm and less than 100 massppm of Mg, with the remainder being Cu and unavoidable impurities, among which the amount of S is 10 massppm or less, the amount of P is 10 massppm or less, the amount of Se is 5 massppm or less, the amount of Te is 5 massppm or less, the amount of Sb is 5 massppm or less, the amount of Bi is 5 massppm or less, the amount of As is 5 massppm or less, the total amount of S, P, Se, Te, Sb, Bi, and As is 30 massppm or less, the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] is 0.6 to 50, the conductivity is 97% IACS or higher, and the residual stress rate is 20% or higher at 150°C and 1000 hours.

Description

Technology Field

[0001] The present invention relates to a copper alloy suitable for components for electronic and electrical devices such as terminals, bus bars, lead frames, heat dissipation members, and heat dissipation substrates, a copper alloy plastically processed material made of the copper alloy, components for electronic and electrical devices, terminals, bus bars, lead frames, and heat dissipation substrates.

[0002] The present application claims priority based on Japanese Patent Application No. 2020-112695 filed in Japan on June 30, 2020, Japanese Patent Application No. 2020-112927 filed in Japan on June 30, 2020, and Japanese Patent Application No. 2020-181734 filed in Japan on October 29, 2020, and incorporates the contents thereof herein. Background Technology

[0003] Conventionally, highly conductive copper or copper alloys are used in components for electronic and electrical devices, such as terminals, bus bars, lead frames, heat dissipation members, and heat dissipation substrates.

[0004] Here, along with the increase in current for electronic and electrical devices, the size and thickness of electronic and electrical components used in these devices are also being increased to reduce current density and dissipate heat caused by Joule heating.

[0005] Here, in order to handle high currents, pure copper materials such as oxygen-free copper with excellent conductivity are applied to the electronic and electrical equipment components described above. However, there was a problem with pure copper materials in that they could not be used in high-temperature environments because their stress relaxation resistance, which indicates the degree of permanent deformation of a spring due to heat, was poor or insufficient.

[0006] Thus, Patent Document 1 discloses a copper rolled plate containing Mg in the range of 0.005 mass% or more and less than 0.1 mass%.

[0007] In the copper rolled plate described in Patent Document 1, since it has a composition comprising Mg in the range of 0.005 mass% or more and less than 0.1 mass%, with the remainder consisting of Cu and unavoidable impurities, it was possible to improve strength and stress relaxation resistance without significantly reducing electrical conductivity by incorporating Mg into the matrix phase of copper.

[0008] However, recently, regarding copper materials constituting the electronic and electrical equipment components described above, there is a requirement to further improve the conductivity in order to sufficiently suppress heat generation when a large current flows and to enable use in applications where pure copper materials were previously used.

[0009] Furthermore, the electronic and electrical equipment components described above are often used in high-temperature environments such as engine rooms, and the copper materials constituting these components require improved stress relaxation resistance compared to conventional materials. In other words, there is a demand for copper materials that improve conductivity and stress relaxation resistance in a good balance.

[0010] In addition, by further significantly improving the conductivity, it becomes possible to use it effectively even in applications where pure copper was conventionally used. Prior art literature

[0011] Japanese Published Patent Application No. 2016-056414 The problem to be solved

[0012] This invention is made in consideration of the aforementioned circumstances and aims to provide a copper alloy having high conductivity and excellent stress relaxation resistance, a copper alloy plastically processed material, a component for electronic and electrical equipment, a terminal, a bus bar, a lead frame, and a heat dissipation substrate. means of solving the problem

[0013] In order to solve this problem, the inventors carefully examined the matter and found that in order to achieve a good balance of high conductivity and excellent stress relaxation resistance, it is necessary to add a small amount of Mg and regulate the content of elements that form compounds with Mg. That is, by regulating the content of elements that form compounds with Mg and allowing the small amount of added Mg to exist in an appropriate form within the copper alloy, it was found that it is possible to improve conductivity and stress relaxation resistance to a higher level than conventional methods and achieve a good balance.

[0014] The present invention is based on the findings described above.

[0015] A copper alloy related to the first aspect of the present invention has a composition in which the content of Mg is in the range of more than 10 massppm and less than 100 massppm, and the remainder is Cu and unavoidable impurities, wherein among the unavoidable impurities, the content of S is 10 massppm or less, the content of P is 10 massppm or less, the content of Se is 5 massppm or less, the content of Te is 5 massppm or less, the content of Sb is 5 massppm or less, the content of Bi is 5 massppm or less, and the content of As is 5 massppm or less, and the total content of S, P, Se, Te, Sb, Bi, and As is 30 massppm or less.

[0016] When the content of Mg is denoted as [Mg] and the total content of S, P, Se, Te, Sb, Bi, and As is denoted as [S + P + Se + Te + Sb + Bi + As], the mass ratio of these [Mg] / [S + P + Se + Te + Sb + Bi + As] is within the range of 0.6 to 50, and

[0017] The conductivity becomes 97% IACS or higher, and

[0018] It is characterized by having a residual stress rate of 20% or more in a direction parallel to the rolling direction at 150°C and 1000 hours.

[0019] According to the copper alloy of this composition, the content of Mg and the elements S, P, Se, Te, Sb, Bi, and As that form compounds with Mg is specified as described above, so that the trace amount of added Mg is dissolved in the matrix phase of copper, thereby improving stress relaxation resistance without significantly reducing conductivity. Specifically, conductivity can be 97% IACS or higher, and residual stress rate in the direction parallel to the rolling direction can be 20% or higher at 150°C and 1000 hours, making it possible to achieve both high conductivity and excellent stress relaxation resistance.

[0020] Here, in the copper alloy related to the first embodiment of the present invention, it is preferable that the Ag content be within the range of 5 massppm or more and 20 massppm or less.

[0021] In this case, since Ag is contained within the range described above, Ag is segregated near the grain boundaries and grain boundary diffusion is suppressed, making it possible to further improve stress relaxation properties.

[0022] In addition, in the copper alloy related to the first embodiment of the present invention, among the above unavoidable impurities, it is preferable that the content of H is 10 massppm or less, the content of O is 100 massppm or less, and the content of C is 10 massppm or less.

[0023] In this case, since the content of H, O, and C is specified as described above, it is possible to reduce the occurrence of defects such as blow holes, Mg oxides, C incorporation, or carbides, and to improve stress relaxation properties without reducing processability.

[0024] In addition, for the copper alloy related to the first embodiment of the present invention, it is preferable that the semi-softening temperature be 200°C or higher.

[0025] In this case, since the semi-softening temperature is 200°C or higher, the heat resistance is sufficiently excellent, and it can be used stably even in high-temperature environments.

[0026] In the copper alloy related to the first aspect of the present invention, 10,000 μm by the EBSD method 2 In the above measurement area, the copper alloy is measured in steps of a measurement interval of 0.25 μm, and the measurement results are analyzed by the data analysis software OIM to obtain the CI value for each measurement point. Excluding measurement points with a CI value of 0.1 or less, the orientation difference of each grain is analyzed. The boundary between measurement points where the orientation difference between adjacent measurement points is 15° or more is defined as the grain boundary. The average grain size A is calculated by the Area Fraction, and the copper alloy is measured by the EBSD method in steps of measurement intervals that are less than or equal to one-tenth of the average grain size A. The total area in multiple fields of view is 10,000 μm so that a total of 1,000 or more grains are included. 2 In the measurement area, the measurement results are analyzed by the data analysis software OIM to obtain the CI value of each measurement point, and excluding measurement points with a CI value of 0.1 or less, the orientation difference of each grain is analyzed, and the boundary between measurement points where the orientation difference between adjacent pixels is 5° or more is considered as a grain boundary, so that the average value of the KAM (Kernel Average Misorientation) is 2.4 or less.

[0027] Since the average value of the KAM is 2.4 or less, it is possible to improve stress relaxation characteristics while maintaining strength.

[0028] The copper alloy plastically processed material related to the first embodiment of the present invention is characterized by being made of the copper alloy related to the first embodiment described above.

[0029] According to the copper alloy plastically processed material of this composition, since it is composed of the copper alloy described above, it exhibits excellent conductivity and stress relaxation resistance, and is particularly suitable as a material for electronic and electrical equipment components such as terminals, bus bars, lead frames, and heat dissipation members (heat dissipation substrates) used in high-current applications and high-temperature environments.

[0030] Here, in the copper alloy plastically processed material related to the first embodiment of the present invention, it may be a rolled plate with a thickness in the range of 0.1 mm or more and 10 mm or less.

[0031] In this case, since the thickness is within the range of 0.1 mm or more and 10 mm or less, by performing stamping or bending on this copper alloy plastic workpiece (rolled plate), components for electronic and electrical equipment such as terminals, bus bars, lead frames, and heat dissipation members can be formed.

[0032] In addition, in the copper alloy plastically processed material related to the first embodiment of the present invention, it is preferable to have a Sn plating layer or an Ag plating layer on the surface.

[0033] That is, the copper alloy plastically processed material related to the first embodiment preferably comprises a main body of the copper alloy plastically processed material and a Sn plating layer or an Ag plating layer formed on the surface of the main body. The main body may be a rolled plate made of the copper alloy related to the first embodiment described above, with a thickness in the range of 0.1 mm or more and 10 mm or less. In this case, since it has a Sn plating layer or an Ag plating layer on the surface, it is particularly suitable as a material for components of electronic and electrical devices such as terminals, bus bars, lead frames, and heat dissipation members. Furthermore, in the first embodiment of the present invention, "Sn plating" includes pure Sn plating or Sn alloy plating, and "Ag plating" includes pure Ag plating or Ag alloy plating.

[0034] The electronic and electrical device component related to the first embodiment of the present invention is characterized by being made of a copper alloy plastically processed material related to the first embodiment described above. In addition, the electronic and electrical device component in the first embodiment of the present invention includes terminals, bus bars, lead frames, heat dissipation members, etc.

[0035] Since the electronic and electrical equipment component of this configuration is manufactured using the copper alloy plastically processed material described above, it can exhibit excellent characteristics even in high-current applications and high-temperature environments.

[0036] The terminal related to the first embodiment of the present invention is characterized by being made of a copper alloy plastically processed material related to the first embodiment described above.

[0037] Since the terminal of this configuration is manufactured using the copper alloy plastically processed material described above, it can exhibit excellent characteristics even in high-current applications and high-temperature environments.

[0038] The bus bar related to the first embodiment of the present invention is characterized by being made of a copper alloy plastically processed material related to the first embodiment described above.

[0039] Since the bus bar of this configuration is manufactured using the copper alloy plastically processed material described above, it can exhibit excellent characteristics even in high-current applications and high-temperature environments.

[0040] The lead frame related to the first embodiment of the present invention is characterized by being made of a copper alloy plastically processed material related to the first embodiment described above.

[0041] Since the lead frame of this configuration is manufactured using the copper alloy plastically processed material described above, it can exhibit excellent characteristics even in high-current applications and high-temperature environments.

[0042] The heat dissipation substrate related to the first embodiment of the present invention is characterized by being manufactured using the copper alloy related to the first embodiment described above.

[0043] Since the heat dissipation substrate of this configuration is manufactured using the copper alloy described above, it can exhibit excellent characteristics even in high-current applications and high-temperature environments.

[0044] A copper alloy related to the second aspect of the present invention has a composition in which the content of Mg is in the range of greater than 10 massppm and less than 100 massppm, and the remainder is Cu and unavoidable impurities, wherein among the unavoidable impurities, the content of S is 10 massppm or less, the content of P is 10 massppm or less, the content of Se is 5 massppm or less, the content of Te is 5 massppm or less, the content of Sb is 5 massppm or less, the content of Bi is 5 massppm or less, and the content of As is 5 massppm or less, and the total content of S, P, Se, Te, Sb, Bi, and As is 30 massppm or less.

[0045] When the content of Mg is denoted as [Mg] and the total content of S, P, Se, Te, Sb, Bi, and As is denoted as [S + P + Se + Te + Sb + Bi + As], the mass ratio of these [Mg] / [S + P + Se + Te + Sb + Bi + As] is within the range of 0.6 to 50, and

[0046] The conductivity becomes 97% IACS or higher, and

[0047] 10,000 µm by EBSD method 2 In the above measurement area, the copper alloy is measured in steps with a measurement interval of 0.25 μm, and the measurement results are analyzed by the data analysis software OIM to obtain the CI value for each measurement point. Excluding measurement points with a CI value of 0.1 or less, the orientation difference of each grain is analyzed. The boundary between measurement points where the orientation difference between adjacent measurement points is 15° or more is defined as the grain boundary. The average grain size A is calculated by the Area Fraction, and the copper alloy is measured by the EBSD method in steps with a measurement interval that is 1 / 10 or less of the average grain size A. The total area in multiple fields of view is 10,000 μm so that a total of 1,000 or more grains are included. 2 In the measurement area, the measurement results are analyzed by the data analysis software OIM to obtain the CI value of each measurement point, and excluding measurement points with a CI value of 0.1 or less, the orientation difference of each grain is analyzed, and the boundary between measurement points where the orientation difference between adjacent pixels is 5° or more is considered as a grain boundary, the average value of the KAM (Kernel Average Misorientation) is 2.4 or less.

[0048] According to the copper alloy of this composition, the content of Mg and the elements S, P, Se, Te, Sb, Bi, and As that form compounds with Mg is specified as described above, so that the trace amount of added Mg is dissolved in the matrix phase of copper, thereby improving stress relaxation resistance without significantly reducing conductivity, and specifically, the conductivity can be made 97% IACS or higher.

[0049] Also, since the average value of the KAM is 2.4 or less, it is possible to improve stress relaxation characteristics while maintaining strength.

[0050] Here, in the copper alloy related to the second embodiment of the present invention, it is preferable that the Ag content be within the range of 5 massppm or more and 20 massppm or less.

[0051] In this case, since Ag is contained within the range described above, Ag is segregated near the grain boundaries and grain boundary diffusion is suppressed, making it possible to further improve stress relaxation properties.

[0052] In addition, in the copper alloy related to the second aspect of the present invention, the residual stress rate RS after holding at 200°C for 4 hours in a direction parallel to the rolling direction. G It is desirable that (%) be 20% or more.

[0053] In this case, the stress relaxation resistance is sufficiently excellent, and it is particularly suitable as a copper alloy for constituting components of electronic and electrical equipment used in high-temperature environments.

[0054] The copper alloy plastically processed material related to the second aspect of the present invention is characterized by being made of the copper alloy related to the second aspect described above.

[0055] According to the copper alloy plastically processed material of this composition, since it is composed of the copper alloy described above, it exhibits excellent conductivity and stress relaxation resistance, and is particularly suitable as a material for electronic and electrical equipment components such as terminals, bus bars, lead frames, and heat dissipation substrates used in high-current applications and high-temperature environments.

[0056] Here, in the copper alloy plastically processed material related to the second aspect of the present invention, it may be a rolled plate with a thickness in the range of 0.1 mm or more and 10 mm or less.

[0057] In this case, since the thickness is within the range of 0.1 mm or more and 10 mm or less, by performing stamping or bending on this copper alloy plastically processed material (rolled plate), components for electronic and electrical devices such as terminals, bus bars, lead frames, and heat dissipation substrates can be formed.

[0058] In addition, in the copper alloy plastically processed material related to the second aspect of the present invention, it is preferable to have a Sn plating layer or an Ag plating layer on the surface.

[0059] That is, the copper alloy plastically processed material related to the second embodiment preferably comprises a main body of the copper alloy plastically processed material and a Sn plating layer or an Ag plating layer formed on the surface of the main body. The main body may be a rolled plate made of the copper alloy related to the second embodiment described above, with a thickness in the range of 0.1 mm or more and 10 mm or less. In this case, since it has a Sn plating layer or an Ag plating layer on the surface, it is particularly suitable as a material for components of electronic and electrical devices such as terminals, bus bars, lead frames, and heat dissipation substrates. Furthermore, in the second embodiment of the present invention, "Sn plating" includes pure Sn plating or Sn alloy plating, and "Ag plating" includes pure Ag plating or Ag alloy plating.

[0060] The electronic and electrical device component related to the second embodiment of the present invention is characterized by being made of a copper alloy plastically processed material related to the second embodiment described above. In addition, the electronic and electrical device component in the second embodiment of the present invention includes terminals, bus bars, lead frames, heat dissipation substrates, etc.

[0061] Since the electronic and electrical equipment component of this configuration is manufactured using the copper alloy plastically processed material described above, it can exhibit excellent characteristics even in high-current applications and high-temperature environments.

[0062] The terminal related to the second aspect of the present invention is characterized by being made of a copper alloy plastically processed material related to the second aspect described above.

[0063] Since the terminal of this configuration is manufactured using the copper alloy plastically processed material described above, it can exhibit excellent characteristics even in high-current applications and high-temperature environments.

[0064] The bus bar related to the second embodiment of the present invention is characterized by being made of a copper alloy plastically processed material related to the second embodiment described above.

[0065] Since the bus bar of this configuration is manufactured using the copper alloy plastically processed material described above, it can exhibit excellent characteristics even in high-current applications and high-temperature environments.

[0066] The lead frame related to the second aspect of the present invention is characterized by being made of a copper alloy plastically processed material related to the second aspect described above.

[0067] Since the lead frame of this configuration is manufactured using the copper alloy plastically processed material described above, it can exhibit excellent characteristics even in high-current applications and high-temperature environments.

[0068] The heat dissipation substrate related to the second aspect of the present invention is characterized by being manufactured using the copper alloy related to the second aspect described above.

[0069] Since the heat dissipation substrate of this configuration is manufactured using the copper alloy described above, it can exhibit excellent characteristics even in high-current applications and high-temperature environments. Effects of the invention

[0070] According to the first and second embodiments of the present invention, it is possible to provide a copper alloy, a copper alloy plastically processed material, a component for electronic and electrical equipment, a terminal, a bus bar, a lead frame, and a heat dissipation substrate having high conductivity and excellent stress relaxation resistance. Brief explanation of the drawing

[0071] FIG. 1 is a flowchart of a method for manufacturing a copper alloy according to the present embodiment. Specific details for implementing the invention

[0072] (First embodiment)

[0073] Below, a copper alloy that is an embodiment of the present invention will be described.

[0074] The copper alloy of the present embodiment has a composition in which the content of Mg is in the range of more than 10 massppm and less than 100 massppm, and the remainder is Cu and unavoidable impurities, and among the unavoidable impurities, the content of S is 10 massppm or less, the content of P is 10 massppm or less, the content of Se is 5 massppm or less, the content of Te is 5 massppm or less, the content of Sb is 5 massppm or less, the content of Bi is 5 massppm or less, and the content of As is 5 massppm or less, and the total content of S, P, Se, Te, Sb, Bi, and As is 30 massppm or less.

[0075] And, when the content of Mg is [Mg] and the total content of S, P, Se, Te, Sb, Bi, and As is [S + P + Se + Te + Sb + Bi + As], the mass ratio of [Mg] / [S + P + Se + Te + Sb + Bi + As] is within the range of 0.6 to 50.

[0076] In addition, in the copper alloy of the present embodiment, the Ag content may be within the range of 5 massppm or more and 20 massppm or less.

[0077] In addition, in the copper alloy of the present embodiment, among the above unavoidable impurities, the content of H may be 10 massppm or less, the content of O may be 100 massppm or less, and the content of C may be 10 massppm or less.

[0078] In addition, in the copper alloy of the present embodiment, the electrical conductivity is 97% IACS or higher, and the residual stress rate in the direction parallel to the rolling direction is 20% or higher at 150°C and 1000 hours.

[0079] In addition, in the copper alloy of the present embodiment, it is preferable that the semi-softening temperature be 200°C or higher.

[0080] Herein, regarding the copper alloy of the present embodiment, the reason for specifying the component composition and various properties as described above is explained below.

[0081] (Mg)

[0082] Mg is an element that, when dissolved in the matrix phase of copper, has the effect of improving stress relaxation resistance without significantly reducing conductivity. In addition, by dissolving Mg in the matrix phase, the semi-softening temperature is improved, thereby enhancing heat resistance.

[0083] Here, if the Mg content is 10 massppm or less, there is a concern that the effect may not be fully exerted. On the other hand, if the Mg content is 100 massppm or more, there is a concern that the conductivity may decrease.

[0084] From the above, in this embodiment, the Mg content is set to a range of more than 10 massppm and less than 100 massppm.

[0085] In addition, to further improve the stress relaxation properties, it is desirable to set the lower limit of the Mg content to 20 massppm or more, more desirable to set it to 30 massppm or more, and more desirable to set it to 40 massppm or more.

[0086] In addition, to further increase the conductivity, it is desirable to set the upper limit of the Mg content to less than 90 massppm. In order to achieve a balance between conductivity, heat resistance, and stress relaxation characteristics when increasing conductivity, it is more desirable to set the upper limit of the Mg content to less than 80 massppm, and even more desirable to set it to less than 70 massppm.

[0087] (S, P, Se, Te, Sb, Bi, As)

[0088] The elements described above, such as S, P, Se, Te, Sb, Bi, and As, are generally elements that are easily incorporated into copper alloys. Furthermore, these elements are prone to reacting with Mg to form compounds, and there is a concern that they may reduce the solid solution effect of trace amounts of Mg. For this reason, it is necessary to strictly control the content of these elements.

[0089] Therefore, in the present embodiment, the content of S is limited to 10 massppm or less, the content of P to 10 massppm or less, the content of Se to 5 massppm or less, the content of Te to 5 massppm or less, the content of Sb to 5 massppm or less, the content of Bi to 5 massppm or less, and the content of As to 5 massppm or less.

[0090] In addition, the total content of S, P, Se, Te, Sb, Bi, and As is limited to 30 massppm or less.

[0091] Although the lower limit of the content of the above elements is not specifically limited, since manufacturing costs increase in order to significantly reduce the content of the above elements, it is preferable that the content of each of S, P, Sb, Bi, and As be 0.1 massppm or more, the content of Se be 0.05 massppm or more, and the content of Te be 0.01 massppm or more.

[0092] Although the lower limit of the total content of S, P, Se, Te, Sb, Bi, and As is not specifically limited, since manufacturing costs increase in order to significantly reduce this total content, it is desirable that the total content of S, P, Se, Te, Sb, Bi, and As be 0.6 massppm or higher.

[0093] In addition, the S content is preferably 9 massppm or less, and more preferably 8 massppm or less.

[0094] The content of P is preferably 6 mass ppm or less, and more preferably 3 mass ppm or less.

[0095] The Se content is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.

[0096] The Te content is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.

[0097] The content of Sb is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.

[0098] The Bi content is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.

[0099] The content of As is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.

[0100] In addition, the total content of S, P, Se, Te, Sb, Bi, and As is preferably 24 massppm or less, and more preferably 18 massppm or less.

[0101] (〔Mg〕 / 〔S + P + Se + Te + Sb + Bi + As〕)

[0102] As described above, elements such as S, P, Se, Te, Sb, Bi, and As are prone to reacting with Mg to form compounds; therefore, in this embodiment, the form in which Mg exists is controlled by defining the ratio of the content of Mg to the total content of S, P, Se, Te, Sb, Bi, and As.

[0103] When the content of Mg is [Mg] and the total content of S, P, Se, Te, Sb, Bi, and As is [S + P + Se + Te + Sb + Bi + As], if the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] exceeds 50, there is a risk that the conductivity will decrease because Mg exists in an excess solid solution state in copper. On the other hand, if the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] is less than 0.6, there is a risk that the stress relaxation resistance will not be sufficiently improved because Mg is not sufficiently solid solution.

[0104] Accordingly, in this embodiment, the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] is set to a range of 0.6 or more and 50 or less.

[0105] In addition, the unit of the content of each element in the above mass ratio is mass ppm.

[0106] In addition, to further increase the conductivity, it is desirable to set the upper limit of the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] to 35 or less, and it is even more desirable to set it to 25 or less.

[0107] In addition, to further improve the internal stress relaxation characteristics, it is desirable to set the lower limit of the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] to 0.8 or higher, and it is even more desirable to set it to 1.0 or higher.

[0108] (Ag: 5 massppm or more, 20 massppm or less)

[0109] Ag cannot be dissolved in the matrix phase of Cu in the operating temperature range of typical electronic and electrical devices below 250°C. For this reason, Ag added in trace amounts to copper becomes segregated near the grain boundaries. As a result, the movement of atoms at the grain boundaries is hindered, and since grain boundary diffusion is suppressed, the stress relaxation resistance is improved.

[0110] Here, when the Ag content is 5 massppm or more, it becomes possible to fully exert the effect. On the other hand, when the Ag content is 20 massppm or less, conductivity is secured while the increase in manufacturing costs can be suppressed.

[0111] From the above, in this embodiment, the Ag content is set within the range of 5 massppm or more and 20 massppm or less.

[0112] In addition, to further improve the stress relaxation resistance, it is desirable to set the lower limit of the Ag content to 6 massppm or more, more desirable to set it to 7 massppm or more, and even more desirable to set it to 8 massppm or more. In addition, to reliably suppress the decrease in conductivity and the increase in cost, it is desirable to set the upper limit of the Ag content to 18 massppm or less, more desirable to set it to 16 massppm or less, and even more desirable to set it to 14 massppm or less.

[0113] In cases where Ag is included as an unavoidable impurity rather than intentionally included, the Ag content may be less than 5 mass ppm.

[0114] (H: 10 massppm or less)

[0115] H is an element that combines with O during casting to become water vapor, causing blowhole defects in the ingot. These blowhole defects cause cracking during casting and defects such as blistering and spalling during rolling. It is known that these defects, such as cracking, blistering, and spalling, deteriorate strength and resistance to stress corrosion cracking because they cause stress concentration and serve as the starting point for fracture.

[0116] Here, by keeping the H content at 10 massppm or less, the occurrence of the blowhole defect described above is suppressed, making it possible to suppress the deterioration of cold workability.

[0117] In addition, to further suppress the occurrence of blowhole defects, it is desirable to keep the H content at 4 mass ppm or less, and even more desirable to keep it at 2 mass ppm or less.

[0118] Although the lower limit of the H content is not specifically limited, since manufacturing costs increase in order to significantly reduce the H content, the H content is preferably 0.01 massppm or higher.

[0119] (O : 100 massppm or less)

[0120] O is an element that reacts with each constituent element in copper alloys to form oxides. Since these oxides serve as starting points for fracture, workability is reduced, making manufacturing difficult. In addition, as excess O reacts with Mg, Mg is consumed, which reduces the solid solution capacity of Mg in the matrix phase of Cu, and there is a risk that cold workability will deteriorate.

[0121] Here, by keeping the O content at 100 mass ppm or less, it is possible to suppress the formation of oxides or the consumption of Mg, thereby improving processability.

[0122] In addition, the O content is particularly preferably 50 massppm or less within the above range, and more preferably 20 massppm or less.

[0123] Although the lower limit of the O content is not specifically limited, since manufacturing costs increase in order to significantly reduce the O content, the O content is preferably 0.01 massppm or more.

[0124] (C: 10 massppm or less)

[0125] C is an element used to coat the surface of the molten metal during melting and casting for the purpose of deoxidizing the molten metal, and there is a risk of it being inevitably incorporated. As the C content increases, the incorporation of C during casting increases. The segregation of these C, complex carbides, and solid solutions of C degrades cold workability.

[0126] Here, by keeping the C content at 10 mass ppm or less, the segregation of C, complex carbides, and solid solutions of C can be suppressed, making it possible to improve cold workability.

[0127] In addition, the content of C is preferably 5 massppm or less within the above range, and more preferably 1 massppm or less.

[0128] Although the lower limit of the C content is not specifically limited, since manufacturing costs increase in order to significantly reduce the C content, the C content is preferably 0.01 massppm or higher.

[0129] (Other unavoidable impurities)

[0130] Other unavoidable impurities other than the elements described above include Al, B, Ba, Be, Ca, Cd, Cr, Sc, rare earth elements, V, Nb, Ta, Mo, Ni, W, Mn, Re, Ru, Sr, Ti, Os, Co, Rh, Ir, Pb, Pd, Pt, Au, Zn, Zr, Hf, Hg, Ga, In, Ge, Y, Tl, N, Si, Sn, Li, etc. These unavoidable impurities may be contained within a range that does not affect the properties.

[0131] Here, since these unavoidable impurities may reduce conductivity, it is desirable to keep the content of unavoidable impurities low.

[0132] (Challenge rate: 97% IACS or higher)

[0133] In the copper alloy of the present embodiment, the conductivity is 97% IACS or higher. By making the conductivity 97% IACS or higher, heat generation during current flow is suppressed, making it possible to use it well as a component for electronic and electrical equipment, such as terminals, bus bars, lead frames, and heat dissipation members, as a substitute for pure copper material.

[0134] In addition, it is desirable that the conductivity be 97.5% IACS or higher, more desirable that it be 98.0% IACS or higher, more desirable that it be 98.5% IACS or higher, and even more desirable that it be 99.0% IACS or higher.

[0135] The upper limit of the conductivity is not specifically limited, but it is preferable to be 103.0 %IACS or less.

[0136] (Residual stress rate (150 ℃, 1000 hours): 20% or more)

[0137] In the copper alloy of the present embodiment, the residual stress rate in the direction parallel to the rolling direction is 20% or more at 150°C for 1000 hours. That is, the residual stress rate after holding at 150°C for 1000 hours is 20% or more. When the residual stress rate under these conditions is high, permanent deformation can be suppressed to a small extent even when used in a high-temperature environment, and the decrease in contact pressure can be suppressed.

[0138] Accordingly, the copper rolled plate of the present embodiment can be applied as a terminal, etc., used in high-temperature environments such as around the engine room of an automobile.

[0139] In addition, the residual stress rate in the direction parallel to the rolling direction is preferably 30% or more at 150°C and 1000 hours, more preferably 40% or more, and even more preferably 50% or more.

[0140] The upper limit of the residual stress rate in the direction parallel to the rolling direction is not particularly limited, but it is preferably 95% or less.

[0141] (Semi-softening temperature: 200 ℃ or higher)

[0142] In the copper alloy of the present embodiment, when the semi-softening temperature is high, it is difficult for softening phenomena caused by the recovery and recrystallization of the copper material to occur even at high temperatures, so it becomes possible to apply it to conductive members used in high-temperature environments.

[0143] For this reason, in the present embodiment, it is preferable that the semi-softening temperature during a 1-hour heat treatment be 200°C or higher. In the present embodiment, the semi-softening temperature is evaluated by measuring Vickers hardness.

[0144] In addition, the semi-softening temperature during 1 hour of heat treatment is more preferably 225 ℃ or higher, more preferably 250 ℃ or higher, and even more preferably 275 ℃ or higher.

[0145] The upper limit of the semi-softening temperature is not specifically limited, but is preferably 600 ℃ or lower.

[0146] (Average KAM value: 2.4 or less)

[0147] Details regarding the average value of the KAM value are explained in the second embodiment. As with the second embodiment, it is preferable that the average value of the KAM value be 2.4 or less. It is preferable that the average value of the KAM value be 2.2 or less, more preferable that it be 2.0 or less, more preferable that it be 1.8 or less, and even more preferable that it be 1.6 or less. It is preferable that the average value of the KAM value be 0.2 or more, more preferable that it be 0.4 or more, even more preferable that it be 0.6 or more, and most preferable that it be 0.8 or more.

[0148] Next, a method for manufacturing a copper alloy of the present embodiment having such a configuration will be explained with reference to the flowchart shown in FIG. 1.

[0149] (Melting and Casting Process S01)

[0150] First, the aforementioned elements are added to the molten copper obtained by melting the copper raw material to adjust the composition, thereby producing a molten copper alloy. Additionally, elemental elements or master alloys may be used for adding various elements. Furthermore, raw materials containing the elements described above may be melted together with the copper raw material. Additionally, recycled and scrap materials of this alloy may be used.

[0151] Here, it is preferable that the copper raw material be so-called 4 N Cu with a purity of 99.99 mass% or higher, or so-called 5 N Cu with a purity of 99.999 mass% or higher. When the content of H, O, and C is specified as described above, raw materials with low content of these elements are selected and used. Specifically, it is preferable to use raw materials with an H content of 0.5 massppm or less, an O content of 2.0 massppm or less, and a C content of 1.0 massppm or less.

[0152] In order to suppress the oxidation of Mg and to reduce the hydrogen concentration, it is desirable to carry out the dissolution in an atmosphere of an inert gas atmosphere (e.g., Ar gas) with a low vapor pressure of H2O, and to keep the holding time during dissolution to a minimum.

[0153] Then, the molten copper alloy with adjusted composition is poured into a mold to produce an ingot. Additionally, when considering mass production, it is preferable to use a continuous casting or semi-continuous casting method.

[0154] (Homogenization / Solution Process S02)

[0155] Next, a heat treatment is performed to homogenize and solution the obtained ingot. Inside the ingot, there may be intermetallic compounds, such as those mainly composed of Cu and Mg, which are generated by the concentration of Mg as segregation during the solidification process. Therefore, to eliminate or reduce these segregations and intermetallic compounds, a heat treatment is performed by heating the ingot to a temperature of 300°C or higher and 1080°C or lower. This causes Mg to diffuse homogeneously within the ingot or to dissolve Mg into the matrix phase. Furthermore, it is preferable to carry out this homogenization / solution process S02 in a non-oxidizing or reducing atmosphere.

[0156] Here, if the heating temperature is below 300 ℃, solution treatment becomes incomplete, and there is a risk that a large amount of intermetallic compounds with Cu and Mg as main components will remain in the matrix. On the other hand, if the heating temperature exceeds 1080 ℃, some of the copper material becomes liquid, and there is a risk that the structure or surface condition will become non-uniform. Therefore, the heating temperature is set to a range of 300 ℃ or higher and 1080 ℃ or lower.

[0157] In addition, to improve the efficiency of the roughing process described later and to ensure uniformity of the structure, hot working may be performed after the aforementioned homogenization / solution process S02. In this case, there are no particular limitations on the processing method, and for example, rolling, drawing, extrusion, groove rolling, forging, pressing, etc., may be employed. Also, it is preferable that the hot working temperature be within the range of 300°C or higher and 1080°C or lower.

[0158] (Rough processing process S03)

[0159] In order to process into a predetermined shape, rough processing is performed. In addition, there are no specific limitations on the temperature conditions in this rough processing process S03, but in order to suppress recrystallization or to improve dimensional accuracy, it is preferable to set the processing temperature within the range of -200°C to 200°C, which is cold or hot processing (e.g., rolling), and room temperature is particularly preferred. Regarding the reduction rate, 20% or more is preferred, and 30% or more is more preferred. In addition, regarding the processing method, there are no specific limitations, and for example, rolling, drawing, extrusion, groove rolling, forging, pressing, etc., may be employed.

[0160] (Intermediate heat treatment process S04)

[0161] After the roughing process S03, heat treatment is performed to soften the material for improved machinability or to create a recrystallized structure.

[0162] At this time, short-term heat treatment by a continuous annealing furnace is preferable, and if Ag is added, localization of segregation of Ag at grain boundaries can be prevented. In addition, the intermediate heat treatment process S04 and the finishing process S05 described later may be repeated.

[0163] (Finishing Process S05)

[0164] In order to process the copper material after the intermediate heat treatment process S04 into a predetermined shape, a finishing process is performed. In addition, although there are no specific limitations on the temperature conditions in this finishing process S05, in order to suppress recrystallization or softening during processing, it is preferable to set the processing temperature within the range of -200°C to 200°C, which is cold or hot processing, and room temperature is particularly preferred. In addition, the reduction rate is appropriately selected to approximate the final shape, but it is preferable to set it to 5% or more to improve strength through work hardening. In addition, if rolling processing is selected, in order to prevent coil marks when wound into a coil and to keep the yield strength at 450 MPa or less, it is preferable to set the reduction rate to 90% or less.

[0165] In addition, regarding the processing method, there are no particular limitations, and, for example, rolling, drawing, extrusion, groove rolling, forging, pressing, etc., can be employed.

[0166] (Mechanical surface treatment process S06)

[0167] After the finishing process S05, mechanical surface treatment is performed. Mechanical surface treatment is a process that applies compressive stress near the surface after the desired shape has been nearly achieved, and it has the effect of improving stress relaxation resistance.

[0168] Mechanical surface treatment can use various commonly used methods such as shot peening, blasting, lapping, polishing, buffing, grinding, sandpaper polishing, tension leveler treatment, and light rolling with a low reduction rate per pass (repeated three or more times with a reduction rate of 1 to 10 percent per pass).

[0169] By applying this mechanical surface treatment to a copper alloy with added Mg, the stress relaxation resistance is significantly improved.

[0170] (Finishing heat treatment process S07)

[0171] Next, for the plastic material obtained by the mechanical surface treatment process S06, a finishing heat treatment may be performed to remove segregation of contained elements into grain boundaries and residual deformation.

[0172] It is preferable that the heat treatment temperature be within the range of 100°C to 500°C. Furthermore, in this finishing heat treatment process S07, it is necessary to set the heat treatment conditions (temperature, time) to avoid a significant decrease in strength due to recrystallization. For example, it is preferable to maintain the temperature at 450°C for about 0.1 seconds to 10 seconds, and at 250°C for 1 minute to 100 hours. It is preferable to perform this heat treatment in a non-oxidizing atmosphere or a reducing atmosphere. Although there are no particular limitations on the method of heat treatment, short-duration heat treatment using a continuous annealing furnace is preferred for the effect of reducing manufacturing costs.

[0173] In addition, the finishing process S05, mechanical surface treatment process S06, and finishing heat treatment process S07 described above may be repeated.

[0174] In this way, the copper alloy (copper alloy plastically processed material) of the present embodiment is provided. Additionally, the copper alloy plastically processed material provided by rolling is referred to as a copper alloy rolled plate.

[0175] Here, when the thickness of the copper alloy plastically processed material (copper alloy rolled plate) is 0.1 mm or more, it is suitable for use as a conductor in high-current applications. In addition, by making the thickness of the copper alloy plastically processed material 10.0 mm or less, the increase in the load of the press machine can be suppressed, thereby ensuring productivity per unit time and reducing manufacturing costs.

[0176] For this reason, it is desirable to have a plate thickness of the copper alloy plastically processed material (copper alloy rolled plate) within the range of 0.1 mm or more and 10.0 mm or less.

[0177] In addition, it is preferable that the lower limit of the plate thickness of the copper alloy plastically processed material (copper alloy rolled plate) be 0.5 mm or more, and more preferable that it be 1.0 mm or more. Meanwhile, it is preferable that the upper limit of the plate thickness of the copper alloy plastically processed material (copper alloy rolled plate) be less than 9.0 mm, and more preferable that it be less than 8.0 mm.

[0178] In the copper alloy of the present embodiment having the above composition, the content of Mg is within the range of more than 10 massppm and less than 100 massppm, and the content of S, an element that forms a compound with Mg, is limited to 10 massppm or less, the content of P is limited to 10 massppm or less, the content of Se is limited to 5 massppm or less, the content of Te is limited to 5 massppm or less, the content of Sb is limited to 5 massppm or less, the content of Bi is limited to 5 massppm or less, and the total content of S, P, Se, Te, Sb, Bi, and As is limited to 30 massppm or less. Therefore, the trace amount of added Mg can be dissolved in the matrix phase of copper, making it possible to improve stress relaxation resistance without significantly reducing electrical conductivity.

[0179] And, when the content of Mg is set to [Mg] and the total content of S, P, Se, Te, Sb, Bi, and As is set to [S + P + Se + Te + Sb + Bi + As], the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] is set within the range of 0.6 to 50, so it is possible to sufficiently improve the stress relaxation properties without reducing the conductivity by excessively dissolving Mg.

[0180] Accordingly, according to the copper alloy of the present embodiment, the conductivity can be 97% IACS or higher, and the residual stress rate in the direction parallel to the rolling direction can be 20% or higher at 150°C and 1000 hours, making it possible to achieve both high conductivity and excellent stress relaxation resistance.

[0181] Specifically, the conductivity can be 97% IACS or higher, and the residual stress rate in the direction parallel to the rolling direction can be 20% or higher at 150°C and 1000 hours, making it possible to achieve both high conductivity and excellent stress relaxation resistance.

[0182] In addition, in the copper alloy of the present embodiment, if the Ag content is within the range of 5 massppm or more and 20 massppm or less, Ag is segregated near the grain boundaries, and grain boundary diffusion is suppressed by this Ag, making it possible to further improve stress relaxation resistance.

[0183] In addition, in the copper alloy of the present embodiment, if the H content is 10 massppm or less, the O content is 100 massppm or less, and the C content is 10 massppm or less, the occurrence of defects such as blow holes, Mg oxides, C incorporation, or carbides can be reduced, and it is possible to improve stress relaxation resistance without reducing processability.

[0184] In addition, in the copper alloy of the present embodiment, if the semi-softening temperature is 200°C or higher, the heat resistance is sufficiently excellent, and it can be used stably even in a high-temperature environment.

[0185] The copper alloy plastically processed material of the present embodiment is composed of the copper alloy described above, and thus has excellent conductivity and stress relaxation resistance, and is particularly suitable as a material for electronic and electrical equipment components such as terminals, bus bars, lead frames, and heat dissipation members.

[0186] In addition, when the copper alloy plastic workpiece of the present embodiment is made into a rolled plate with a thickness in the range of 0.1 mm or more and 10 mm or less, electronic and electrical equipment components such as terminals, bus bars, lead frames, and heat dissipation members can be formed relatively easily by performing stamping or bending processes on the copper alloy plastic workpiece (rolled plate).

[0187] In addition, when a Sn plating layer or an Ag plating layer is formed on the surface of the copper alloy plastically processed material of the present embodiment, it is particularly suitable as a material for electronic and electrical equipment components such as terminals, bus bars, and heat dissipation members.

[0188] In addition, the electronic and electrical equipment components (terminals, bus bars, lead frames, heat dissipation members, etc.) of this embodiment are composed of the copper alloy plastically processed material described above, so they can exhibit excellent characteristics even in high-current applications and high-temperature environments.

[0189] In addition, the heat dissipation member (heat dissipation substrate) may be manufactured using the copper alloy described above.

[0190] Although copper alloys, copper alloy plastic processed materials, and electronic and electrical equipment components (terminals, bus bars, lead frames, etc.) that are embodiments of the present invention have been described above, the present invention is not limited thereto and can be appropriately modified within the scope of not deviating from the technical requirements of the invention.

[0191] For example, in the embodiments described above, an example of a method for manufacturing a copper alloy (a copper alloy plastically processed material) was explained, but the method for manufacturing a copper alloy is not limited to that described in the embodiments, and it may be manufactured by appropriately selecting existing manufacturing methods.

[0192] (Second embodiment)

[0193] Below, a copper alloy that is an embodiment of the present invention will be described.

[0194] The copper alloy of the present embodiment has a composition in which the content of Mg is in the range of more than 10 massppm and less than 100 massppm, and the remainder is Cu and unavoidable impurities, and among the unavoidable impurities, the content of S is 10 massppm or less, the content of P is 10 massppm or less, the content of Se is 5 massppm or less, the content of Te is 5 massppm or less, the content of Sb is 5 massppm or less, the content of Bi is 5 massppm or less, and the content of As is 5 massppm or less, and the total content of S, P, Se, Te, Sb, Bi, and As is 30 massppm or less.

[0195] And, when the content of Mg is [Mg] and the total content of S, P, Se, Te, Sb, Bi, and As is [S + P + Se + Te + Sb + Bi + As], the mass ratio of [Mg] / [S + P + Se + Te + Sb + Bi + As] is within the range of 0.6 to 50.

[0196] In addition, in the copper alloy of the present embodiment, the Ag content may be within the range of 5 massppm or more and 20 massppm or less.

[0197] In addition, in the copper alloy of the present embodiment, the conductivity is 97% IACS or higher.

[0198] In addition, in the copper alloy of the present embodiment, the residual stress rate RS after holding at 200°C for 4 hours in a direction parallel to the rolling direction G It is desirable that (%) be 20% or more.

[0199] And, in the copper alloy of the present embodiment, 10,000 μm by the EBSD method 2 In the above measurement area, the copper alloy is measured in steps with a measurement interval of 0.25 μm. The measurement results are analyzed using the data analysis software OIM to obtain the CI value for each measurement point. Measurement points with a CI value of 0.1 or less are excluded. The orientation difference of each grain is analyzed using the data analysis software OIM, and the boundaries between adjacent measurement points where the orientation difference is 15° or more are defined as grain boundaries. The average grain size A is calculated using the Area Fraction with the data analysis software OIM. The copper alloy is measured by the EBSD method in steps with a measurement interval that is less than or equal to one-tenth of the average grain size A. To include a total of 1,000 or more grains, the total area across multiple fields of view is 10,000 μm. 2 In the measurement area, the measurement results are analyzed by the data analysis software OIM to obtain the CI value for each measurement point. Measurement points with a CI value of 0.1 or less are excluded. The orientation difference of each grain is analyzed by the data analysis software OIM, and the boundary between measurement points where the orientation difference between adjacent pixels (measurement points) is 5° or more is considered as a grain boundary. In this case, the average value of the KAM (Kernel Average Misorientation) is 2.4 or less.

[0200] Herein, regarding the copper alloy of the present embodiment, the reasons for specifying the composition, structure, and various properties as described above are explained below.

[0201] (Mg)

[0202] Mg is an element that, when dissolved in the matrix phase of copper, has the effect of improving strength and stress relaxation resistance without significantly reducing conductivity. In addition, by dissolving Mg in the matrix phase, heat resistance is also improved.

[0203] Here, if the Mg content is 10 massppm or less, there is a concern that the effect may not be fully exerted. On the other hand, if the Mg content is 100 massppm or more, there is a concern that the conductivity may decrease.

[0204] From the above, in this embodiment, the Mg content is set to a range of more than 10 massppm and less than 100 massppm.

[0205] In addition, to further improve the stress relaxation properties, it is desirable to set the lower limit of the Mg content to 20 massppm or more, more desirable to set it to 30 massppm or more, and more desirable to set it to 40 massppm or more.

[0206] In addition, to further increase the conductivity, it is desirable to set the upper limit of the Mg content to less than 90 massppm. In order to achieve a balance between conductivity, heat resistance, and stress relaxation characteristics when increasing conductivity, it is more desirable to set the upper limit of the Mg content to less than 80 massppm, and even more desirable to set it to less than 70 massppm.

[0207] (S, P, Se, Te, Sb, Bi, As)

[0208] The elements described above, such as S, P, Se, Te, Sb, Bi, and As, are generally elements that are easily incorporated into copper alloys. Furthermore, these elements are prone to reacting with Mg to form compounds, and there is a concern that they may reduce the solid solution effect of trace amounts of Mg. For this reason, it is necessary to strictly control the content of these elements.

[0209] Therefore, in the present embodiment, the content of S is limited to 10 massppm or less, the content of P to 10 massppm or less, the content of Se to 5 massppm or less, the content of Te to 5 massppm or less, the content of Sb to 5 massppm or less, the content of Bi to 5 massppm or less, and the content of As to 5 massppm or less.

[0210] In addition, the total content of S, P, Se, Te, Sb, Bi, and As is limited to 30 massppm or less.

[0211] Although the lower limit of the content of the above elements is not specifically limited, since manufacturing costs increase in order to significantly reduce the content of the above elements, it is preferable that the content of each of S, P, Sb, Bi, and As be 0.1 massppm or more, the content of Se be 0.05 massppm or more, and the content of Te be 0.01 massppm or more.

[0212] Although the lower limit of the total content of S, P, Se, Te, Sb, Bi, and As is not specifically limited, since manufacturing costs increase in order to significantly reduce this total content, it is desirable that the total content of S, P, Se, Te, Sb, Bi, and As be 0.6 massppm or higher.

[0213] In addition, the S content is preferably 9 massppm or less, and more preferably 8 massppm or less.

[0214] The content of P is preferably 6 mass ppm or less, and more preferably 3 mass ppm or less.

[0215] The Se content is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.

[0216] The Te content is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.

[0217] The content of Sb is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.

[0218] The Bi content is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.

[0219] The content of As is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.

[0220] In addition, the total content of S, P, Se, Te, Sb, Bi, and As is preferably 24 massppm or less, and more preferably 18 massppm or less.

[0221] (〔Mg〕 / 〔S + P + Se + Te + Sb + Bi + As〕)

[0222] As described above, elements such as S, P, Se, Te, Sb, Bi, and As are prone to reacting with Mg to form compounds; therefore, in this embodiment, the form in which Mg exists is controlled by defining the ratio of the content of Mg to the total content of S, P, Se, Te, Sb, Bi, and As.

[0223] When the content of Mg is [Mg] and the total content of S, P, Se, Te, Sb, Bi, and As is [S + P + Se + Te + Sb + Bi + As], if the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] exceeds 50, there is a risk that Mg exists in an excess solid solution state in copper and the conductivity may decrease. On the other hand, if the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] is less than 0.6, there is a risk that Mg is not sufficiently solidified and the stress relaxation resistance may not be sufficiently improved.

[0224] Accordingly, in this embodiment, the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] is set to a range of 0.6 or more and 50 or less.

[0225] In addition, the unit of the content of each element in the above mass ratio is mass ppm.

[0226] In addition, to further suppress the decrease in conductivity, it is desirable to set the upper limit of the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] to 35 or less, and it is even more desirable to set it to 25 or less.

[0227] In addition, to further improve the internal stress relaxation characteristics, it is desirable to set the lower limit of the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] to 0.8 or higher, and it is even more desirable to set it to 1.0 or higher.

[0228] (Ag: 5 massppm or more, 20 massppm or less)

[0229] Ag cannot be dissolved in the matrix phase of Cu in the operating temperature range of typical electronic and electrical devices at 250°C or lower. For this reason, Ag added in trace amounts to copper becomes segregated near the grain boundaries. As a result, the movement of atoms at the grain boundaries is hindered, and since grain boundary diffusion is suppressed, the stress relaxation resistance is improved.

[0230] Here, when the Ag content is 5 massppm or more, it becomes possible to fully exert the effect. On the other hand, when the Ag content is 20 massppm or less, conductivity is secured while the increase in manufacturing costs can be suppressed.

[0231] From the above, in this embodiment, the Ag content is set within the range of 5 massppm or more and 20 massppm or less.

[0232] In addition, to further improve the stress relaxation resistance, it is desirable to set the lower limit of the Ag content to 6 massppm or more, more desirable to set it to 7 massppm or more, and even more desirable to set it to 8 massppm or more. In addition, to reliably suppress the decrease in conductivity and the increase in cost, it is desirable to set the upper limit of the Ag content to 18 massppm or less, more desirable to set it to 16 massppm or less, and even more desirable to set it to 14 massppm or less.

[0233] In addition, if Ag is included as an unavoidable impurity rather than intentionally included, the Ag content may be less than 5 mass ppm.

[0234] (Other unavoidable impurities)

[0235] Other unavoidable impurities other than the elements described above include Al, B, Ba, Be, Ca, Cd, Cr, Sc, rare earth elements, V, Nb, Ta, Mo, Ni, W, Mn, Re, Ru, Sr, Ti, Os, Co, Rh, Ir, Pb, Pd, Pt, Au, Zn, Zr, Hf, Hg, Ga, In, Ge, Y, Tl, N, Si, Sn, Li, etc. These unavoidable impurities may be contained within a range that does not affect the properties.

[0236] Here, since these unavoidable impurities may reduce conductivity, it is desirable to keep the content of unavoidable impurities low.

[0237] (Challenge rate: 97% IACS or higher)

[0238] In the copper alloy of the present embodiment, the conductivity is 97% IACS or higher. By making the conductivity 97% IACS or higher, heat generation during current flow is suppressed, making it possible to use it well as a component for electronic and electrical equipment, such as terminals, bus bars, lead frames, and heat dissipation substrates, as a substitute for pure copper material.

[0239] In addition, it is desirable that the conductivity be 97.5% IACS or higher, more desirable that it be 98.0% IACS or higher, more desirable that it be 98.5% IACS or higher, and even more desirable that it be 99.0% IACS or higher.

[0240] The upper limit of the conductivity is not specifically limited, but it is preferable to be 103.0 %IACS or less.

[0241] (Residual stress rate RS after holding at 200°C for 4 hours in a direction parallel to the rolling direction G (%) : 20% or more)

[0242] In the copper alloy of the present embodiment, the residual stress rate RS after holding at 200°C for 4 hours in a direction parallel to the rolling direction GIt is desirable that (%) be 20% or more.

[0243] When the residual stress rate is high under these conditions, permanent deformation can be minimized and the drop in contact pressure can be suppressed even when used in a high-temperature environment. Therefore, the copper alloy of this embodiment is particularly suitable as a terminal used in high-temperature environments, such as around the engine room of an automobile.

[0244] In addition, the residual stress rate RS after holding at 200°C for 4 hours in a direction parallel to the rolling direction G (%) is more preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more.

[0245] (Average KAM value: 2.4 or less)

[0246] The Kernel Average Misorientation (KAM) value measured by EBSD is a value calculated by averaging the orientation difference between a single pixel and the surrounding pixels. Since the shape of a pixel is a regular hexagon, when the order of proximity is set to 1 (1st), the average of the orientation differences with six adjacent pixels is calculated as the KAM value. By using this KAM value, the distribution of local orientation differences, i.e., deformation, can be visualized.

[0247] This region with a high KAM value is a region with a high density of dislocations (GN dislocations) introduced during processing, so high-speed diffusion of atoms along the dislocations is likely to occur, and stress relaxation is likely to occur.

[0248] Therefore, by controlling the average value of this KAM value to 2.4 or less, it becomes possible to improve stress relaxation characteristics while maintaining strength.

[0249] In addition, within the above range, the average value of the KAM is preferably 2.2 or less, more preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.6 or less. Meanwhile, although there is no particular limit on the lower limit of the average value of the KAM, in order to secure work hardening amount and obtain sufficient strength, the average value of the KAM is more preferably 0.2 or higher, more preferably 0.4 or higher, even more preferably 0.6 or higher, and most preferably 0.8 or higher.

[0250] In addition, in this embodiment, the KAM value is calculated by excluding measurement points where the CI (Confidence Index) value, which is a value measured by the EBSD device analysis software OIM Analysis (Ver. 7.3.1), is 0.1 or less. The CI value is calculated by using the Voting method when indexing the EBSD pattern obtained from a given analysis point, and takes a value between 0 and 1. Since the CI value is a value that evaluates the reliability of indexing and orientation calculation, if the CI value is low, that is, if a clear determination pattern of the analysis point is not obtained, it can be said that deformation (processed structure) exists in the structure. In particular, if the deformation is large, the CI value takes a value of 0.1 or less.

[0251] Next, a method for manufacturing a copper alloy of the present embodiment having such a configuration will be explained with reference to the flowchart shown in FIG. 1.

[0252] (Melting and Casting Process S01)

[0253] First, the composition is adjusted by adding the aforementioned elements to the molten copper obtained by melting the copper raw material, thereby producing a molten copper alloy. Additionally, for the addition of various elements, pure elements or master alloys may be used. Furthermore, a raw material containing the elements described above may be melted together with the copper raw material. Additionally, recycled and scrap materials of this alloy may be used.

[0254] Here, it is preferable that the copper raw material be so-called 4 N Cu with a purity of 99.99 mass% or higher, or so-called 5 N Cu with a purity of 99.999 mass% or higher.

[0255] In order to suppress the oxidation of Mg and to reduce the hydrogen concentration, it is desirable to carry out the dissolution in an atmosphere of an inert gas atmosphere (e.g., Ar gas) with a low vapor pressure of H2O, and to keep the holding time during dissolution to a minimum.

[0256] Then, the molten copper alloy with adjusted composition is poured into a mold to produce an ingot. Additionally, when considering mass production, it is preferable to use a continuous casting or semi-continuous casting method.

[0257] (Homogenization / Solution Process S02)

[0258] Next, a heat treatment is performed to homogenize and solution the obtained ingot. Inside the ingot, there may be intermetallic compounds, such as those mainly composed of Cu and Mg, which are generated by the concentration of Mg as segregation during the solidification process. Therefore, to eliminate or reduce these segregations and intermetallic compounds, a heat treatment is performed by heating the ingot to a temperature of 300°C or higher and 1080°C or lower. This causes Mg to diffuse homogeneously within the ingot or to dissolve Mg into the matrix phase. Furthermore, it is preferable to carry out this homogenization / solution process S02 in a non-oxidizing or reducing atmosphere.

[0259] Here, if the heating temperature is below 300 ℃, solution treatment becomes incomplete, and there is a risk that a large amount of intermetallic compounds with Cu and Mg as main components will remain in the matrix. On the other hand, if the heating temperature exceeds 1080 ℃, some of the copper material becomes liquid, and there is a risk that the structure or surface condition will become non-uniform. Therefore, the heating temperature is set to a range of 300 ℃ or higher and 1080 ℃ or lower.

[0260] In addition, to improve the efficiency of the roughing process described later and to ensure uniformity of the structure, hot working may be performed after the aforementioned homogenization / solution process S02. In this case, there are no particular limitations on the processing method, and for example, rolling, drawing, extrusion, groove rolling, forging, pressing, etc., may be employed. Also, it is preferable that the hot working temperature be within the range of 300°C or higher and 1080°C or lower.

[0261] (Rough processing process S03)

[0262] In order to process into a predetermined shape, rough processing is performed. In addition, there are no specific limitations on the temperature conditions in this rough processing process S03, but in order to suppress recrystallization or to improve dimensional accuracy, it is preferable to set the processing temperature within the range of -200°C to 200°C, which is cold or hot processing (e.g., rolling), and room temperature is particularly preferred. Regarding the reduction rate, 20% or more is preferred, and 30% or more is more preferred. In addition, regarding the processing method, there are no specific limitations, and for example, rolling, drawing, extrusion, groove rolling, forging, pressing, etc., may be employed.

[0263] (Intermediate heat treatment process S04)

[0264] After the roughing process S03, heat treatment is performed to obtain a recrystallized structure. Additionally, the intermediate heat treatment process S04 and the finishing process S05 described later may be repeated.

[0265] Here, since this intermediate heat treatment process S04 is substantially the final recrystallization heat treatment, the crystal grain size of the recrystallized structure obtained in this process becomes almost identical to the final crystal grain size. Therefore, in this intermediate heat treatment process S04, it is desirable to appropriately select heat treatment conditions so that the average crystal grain size is 5 μm or more. For example, it is desirable to maintain the temperature at 700 ℃ for about 1 second to 120 seconds.

[0266] (Finishing Process S05)

[0267] In order to process the copper material after the intermediate heat treatment process S04 into a predetermined shape, a finishing process is performed. In addition, although there are no specific limitations on the temperature conditions in this finishing process S05, in order to suppress recrystallization or softening during processing, it is preferable to set the processing temperature within the range of -200°C to 200°C, which is cold or hot processing, and room temperature is particularly preferred. Furthermore, the reduction rate is appropriately selected to approximate the final shape, but it is preferable to set it to 5% or more to improve strength through work hardening. On the other hand, to suppress an excessive increase in the KAM value, it is preferable to set the reduction rate to 85% or less, and it is more preferable to set the reduction rate to 80% or less.

[0268] In addition, regarding the processing method, there are no particular limitations, and, for example, rolling, drawing, extrusion, groove rolling, forging, pressing, etc., can be employed.

[0269] (Mechanical surface treatment process S06)

[0270] After the finishing process S05, mechanical surface treatment is performed. Mechanical surface treatment is a process that applies compressive stress near the surface after the desired shape has been nearly obtained, and it has the effect of improving stress relaxation resistance.

[0271] Mechanical surface treatment can use various commonly used methods such as shot peening, blasting, lapping, polishing, buffing, grinding, sandpaper polishing, tension leveler treatment, and light rolling with a low reduction rate per pass (repeated three or more times with a reduction rate of 1 to 10 percent per pass).

[0272] By applying this mechanical surface treatment to a copper alloy with added Mg, the stress relaxation resistance is significantly improved.

[0273] (Finishing heat treatment process S07)

[0274] Next, for the plastic material obtained by the mechanical surface treatment process S06, a finishing heat treatment is performed to remove segregation of contained elements into grain boundaries and residual deformation.

[0275] It is preferable that the heat treatment temperature be within the range of 100°C to 500°C. Furthermore, in this finishing heat treatment process S07, it is necessary to set heat treatment conditions to avoid a significant decrease in strength due to recrystallization, and to optimize the dislocation arrangement by removing residual strain to reduce the excessively increased KAM value. For example, it is preferable to maintain the temperature at 450°C for about 0.1 seconds to 10 seconds, and at 250°C for 1 minute to 100 hours. It is preferable to perform this heat treatment in a non-oxidizing or reducing atmosphere. Although there are no particular limitations on the method of heat treatment, short-duration heat treatment using a continuous annealing furnace is preferred due to the effect of reducing manufacturing costs.

[0276] In addition, the finishing process S05, mechanical surface treatment process S06, and finishing heat treatment process S07 described above may be repeated.

[0277] In this way, the copper alloy (copper alloy plastically processed material) of the present embodiment is provided. Additionally, the copper alloy plastically processed material provided by rolling is referred to as a copper alloy rolled plate.

[0278] Here, when the thickness of the copper alloy plastically processed material (copper alloy rolled plate) is 0.1 mm or more, it is suitable for use as a conductor in high-current applications. In addition, by making the thickness of the copper alloy plastically processed material 10.0 mm or less, the increase in the load of the press machine can be suppressed, thereby ensuring productivity per unit time and reducing manufacturing costs.

[0279] For this reason, it is desirable to have a plate thickness of the copper alloy plastically processed material (copper alloy rolled plate) within the range of 0.1 mm or more and 10.0 mm or less.

[0280] In addition, it is preferable that the lower limit of the plate thickness of the copper alloy plastically processed material (copper alloy rolled plate) be 0.5 mm or more, and more preferable that it be 1.0 mm or more. Meanwhile, it is preferable that the upper limit of the plate thickness of the copper alloy plastically processed material (copper alloy rolled plate) be less than 9.0 mm, and more preferable that it be less than 8.0 mm.

[0281] In the copper alloy of the present embodiment having the above composition, the content of Mg is within the range of more than 10 massppm and less than 100 massppm, and the content of S, an element that forms a compound with Mg, is limited to 10 massppm or less, the content of P is limited to 10 massppm or less, the content of Se is limited to 5 massppm or less, the content of Te is limited to 5 massppm or less, the content of Sb is limited to 5 massppm or less, the content of Bi is limited to 5 massppm or less, and the total content of S, P, Se, Te, Sb, Bi, and As is limited to 30 massppm or less. Therefore, the trace amount of added Mg can be dissolved in the matrix phase of copper, making it possible to improve stress relaxation resistance without significantly reducing electrical conductivity.

[0282] Furthermore, when the Mg content is set to [Mg] and the total content of S, P, Se, Te, Sb, Bi, and As is set to [S + P + Se + Te + Sb + Bi + As], the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] is set within the range of 0.6 to 50, thereby making it possible to sufficiently improve stress relaxation resistance without reducing conductivity due to excessive dissolution of Mg. Accordingly, according to the copper alloy of the present embodiment, conductivity is 97% IACS or higher, and the residual stress rate RS after holding at 200°C for 4 hours in a direction parallel to the rolling direction G (%) can be made 20% or more, making it possible to achieve both high conductivity and excellent stress relaxation properties.

[0283] In addition, in this embodiment, since the average value of the KAM is 2.4 or less, it is possible to improve stress relaxation characteristics while maintaining strength.

[0284] In this embodiment, when the Ag content is within the range of 5 massppm or more and 20 massppm or less, Ag is segregated near the grain boundary, and grain boundary diffusion is suppressed by this Ag, making it possible to further improve stress relaxation properties.

[0285] The copper alloy plastically processed material of the present embodiment is composed of the copper alloy described above, and thus has excellent conductivity and stress relaxation resistance, and is particularly suitable as a material for components of electronic and electrical devices such as terminals, bus bars, lead frames, and heat dissipation substrates.

[0286] In addition, when the copper alloy plastic workpiece of the present embodiment is made into a rolled plate with a thickness in the range of 0.1 mm or more and 10 mm or less, by performing stamping or bending on the copper alloy plastic workpiece (rolled plate), components for electronic and electrical devices such as terminals, bus bars, lead frames, and heat dissipation substrates can be formed relatively easily.

[0287] In addition, when a Sn plating layer or an Ag plating layer is formed on the surface of the copper alloy plastically processed material of the present embodiment, it is particularly suitable as a material for electronic and electrical equipment components such as terminals, bus bars, lead frames, and heat dissipation substrates.

[0288] In addition, the electronic and electrical equipment components (terminals, bus bars, lead frames, heat dissipation substrates, etc.) of this embodiment are composed of the copper alloy plastically processed material described above, so they can exhibit excellent characteristics even in high-current applications and high-temperature environments.

[0289] In addition, the heat dissipation member (heat dissipation substrate) may be manufactured using the copper alloy described above.

[0290] Although copper alloys, copper alloy plastic processed materials, and electronic and electrical equipment components (terminals, bus bars, lead frames, heat dissipation substrates) that are embodiments of the present invention have been described above, the present invention is not limited thereto and can be appropriately modified within the scope of not deviating from the technical requirements of the invention.

[0291] For example, in the embodiments described above, an example of a method for manufacturing a copper alloy (a copper alloy plastically processed material) was explained, but the method for manufacturing a copper alloy is not limited to that described in the embodiments, and it may be manufactured by appropriately selecting existing manufacturing methods.

[0292] Examples

[0293] (Example 1)

[0294] Below, the results of a verification experiment conducted to confirm the effects of the first embodiment will be described.

[0295] Copper raw materials were prepared with an H content of 0.1 massppm or less, an O content of 1.0 massppm or less, an S content of 1.0 massppm or less, a C content of 0.3 massppm or less, and a Cu purity of 99.99 mass% or more. In addition, high-purity copper of 6 N (purity 99.9999 mass%) or higher and pure metal having a purity of 2 N (purity 99 mass%) or higher were used to manufacture and prepare master alloys containing 1 mass% of various additive elements.

[0296] The copper raw material described above was loaded into a high-purity alumina crucible and melted using a high-frequency melting furnace in a high-purity Ar gas atmosphere (dew point -80°C or lower).

[0297] In the obtained molten copper, the master alloy described above was used to prepare the compositional compositions shown in Tables 1 and 2. When H and O were introduced, the atmosphere during melting was set to an Ar-N2-H2 and Ar-O2 mixed gas atmosphere by using high-purity Ar gas (dew point -80°C or lower), high-purity N2 gas (dew point -80°C or lower), high-purity O2 gas (dew point -80°C or lower), and high-purity H2 gas (dew point -80°C or lower). When C was introduced, C particles were coated onto the surface of the molten metal during melting and brought into contact with the molten metal.

[0298] Thus, a molten alloy with the compositional components shown in Tables 1 and 2 was melted and poured into an insulating material (isosol) mold to produce an ingot. In addition, the thickness of the ingot was set to approximately 30 mm.

[0299] For the obtained ingot, heating was performed at 900°C for 1 hour in an Ar gas atmosphere to solve Mg, surface grinding was performed to remove the oxide film, and the ingot was cut to a predetermined size.

[0300] Afterwards, cutting was performed by adjusting the thickness to achieve the appropriate final thickness. Each cut sample was rough rolled under the conditions listed in Tables 3 and 4. Subsequently, an intermediate heat treatment was performed under conditions where the crystal grain size became approximately 30 μm through recrystallization.

[0301] Next, finish rolling (finishing process) was performed under the conditions listed in Tables 3 and 4.

[0302] Then, a mechanical surface treatment process was performed on these samples using the method described in Tables 3 and 4.

[0303] In addition, buffing was performed using #800 abrasive paper.

[0304] A tension leveler equipped with multiple φ10 mm rolls was used, and the tension was performed with a line tension of 100 N / mm².

[0305] Light rolling (rolling with a low reduction rate per pass) was carried out with a final 5 passes at a reduction rate of 5% per pass.

[0306] Afterwards, finishing heat treatment was performed under the conditions listed in Tables 3 and 4, and strips with a thickness × width of approximately 60 mm, as listed in Tables 3 and 4, were submitted.

[0307] Regarding the obtained materials, an evaluation was conducted on the following items.

[0308] (Composition Analysis)

[0309] Measurement samples were taken from the obtained ingot, and the amount of Mg was measured by inductively coupled plasma emission spectroscopy, and the amounts of other elements were measured using a glow discharge mass spectrometer (GD-MS). In addition, the quantitative analysis of H was performed by thermal conductivity, and the quantitative analysis of O, S, and C was performed by infrared absorption.

[0310] In addition, measurements were taken at two points, one at the center of the sample and the other at the end in the width direction, and the one with the higher content was taken as the content of that sample. As a result, it was confirmed that the component composition was as shown in Tables 1 and 2.

[0311] (Challenge Rate)

[0312] A test specimen with a width of 10 mm × a length of 60 mm was taken from the material for characteristic evaluation, and its electrical resistance was determined using the four-terminal method. Additionally, the dimensions of the test specimen were measured using a micrometer, and its volume was calculated. Then, the conductivity was calculated from the measured electrical resistance values ​​and volume. Furthermore, the test specimen was taken such that its length direction was parallel to the rolling direction of the material for characteristic evaluation. The evaluation results are shown in Tables 3 and 4.

[0313] (Internal stress relaxation characteristics)

[0314] For the stress relaxation resistance test, stress was applied according to the method of the cantilever screw type of the Japan Copper Association Technical Standard JCBA-T309:2004, and the residual stress rate was measured after maintaining at a temperature of 150°C for 1,000 hours. The evaluation results are shown in Tables 3 and 4.

[0315] For the test method, a test specimen (width 10 mm) was taken from each material for characteristic evaluation in a direction parallel to the rolling direction, the initial bending displacement was set to 2 mm and the span length was adjusted so that the maximum surface stress of the test specimen was 80% of the yield strength. The maximum surface stress is determined by the following formula.

[0316] Maximum surface stress (MPa) = 1.5Etδ0 / L s 2

[0317] However, each symbol represents the following values.

[0318] E : Young's modulus (MPa)

[0319] t : Thickness of sample (mm)

[0320] δ0: Initial bending displacement (mm)

[0321] L s : Span length (mm)

[0322] The residual stress rate in the direction parallel to the rolling direction was measured from the bending mark after holding for 1,000 hours at a temperature of 150 ℃, and the stress relaxation resistance was evaluated. In addition, the residual stress rate was calculated using the following formula.

[0323] Residual stress rate (%) = (1 - δ t / δ0) × 100

[0324] However, each symbol represents the following values.

[0325] δ t : (Permanent bending displacement after holding at 150 ℃ for 1,000 hours (mm)) - (Permanent bending displacement after holding at room temperature for 24 hours (mm))

[0326] δ0: Initial bending displacement (mm)

[0327] (Semi-softening temperature)

[0328] The semi-softening temperature (the heat treatment temperature at which the hardness value is intermediate between the initial hardness value and the hardness value after full heat treatment) was evaluated by obtaining an isochronous softening curve based on Vickers hardness during a 1-hour heat treatment, with reference to JCBA T325:2013 of the Japan Copper Industry Association. In addition, the measurement surface for Vickers hardness was the rolled surface. The evaluation results are shown in Tables 3 and 4.

[0329] (Mechanical properties)

[0330] Test specimen No. 13B as specified in JIS Z 2241 was taken from the material for characteristic evaluation, and the 0.2% yield strength was measured by the offset method of JIS Z 2241. In addition, the test specimen was taken in a direction parallel to the rolling direction. The evaluation results are shown in Tables 3 and 4.

[0331] (Number of fractures in tensile test)

[0332] Tensile tests were performed 10 times using the above No. 13B test specimen, and the number of tensile test specimens that fractured in the elastic region before reaching 0.2% yield strength was defined as the number of fractures in the tensile test, and measurements were taken. The evaluation results are shown in Tables 3 and 4.

[0333] Furthermore, the elastic zone refers to the region of the stress-strain curve that satisfies a linear relationship. As the number of fractures increases, workability deteriorates due to inclusions.

[0334]

[0335]

[0336]

[0337]

[0338] Comparative Example 1-1 had a lower residual stress rate and insufficient stress relaxation resistance because the Mg content was lower than that of the first embodiment.

[0339] Comparative Examples 1-2 have a Mg content that exceeds the range of the first embodiment, and the conductivity has decreased.

[0340] Comparative Examples 1-3 had a total content of S, P, Se, Te, Sb, Bi, and As exceeding 30 massppm, a low residual stress rate, and insufficient stress relaxation resistance.

[0341] Comparative Examples 1-4 had a mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] of less than 0.6, a low residual stress rate, and insufficient stress relaxation resistance.

[0342] In this regard, in Examples 1-1 to 1-23 of the present invention, it was confirmed that the conductivity and stress relaxation resistance characteristics were improved in a good balance. In addition, processability was also excellent.

[0343] From the above, it has been confirmed that, according to the embodiments of the present invention, it is possible to provide a copper alloy having high conductivity and excellent stress relaxation resistance, as well as excellent processability.

[0344] (Example 2)

[0345] Below, the results of a verification experiment conducted to confirm the effects of the second embodiment will be described.

[0346] A raw material consisting of pure copper with a purity of 99.999 mass% or higher obtained by the band melting and refining method was loaded into a high-purity graphite crucible and melted at high frequency in an atmosphere of Ar gas.

[0347] A master alloy containing 0.1 mass% of various additive elements was prepared using high-purity copper of 6 N (99.9999 mass%) or higher and pure metal having a purity of 2 N (99 mass%) or higher. The composition was adjusted by adding the master alloy to the obtained molten copper, and an ingot with the compositional composition shown in Tables 5 and 6 was produced by pouring the molten copper into an insulating material (isoul) mold. In addition, the size of the ingot was set to a thickness of approximately 30 mm × a width of approximately 60 mm × a length of approximately 150 to 200 mm.

[0348] For the obtained ingot, heating was performed at 900°C for 1 hour in an Ar gas atmosphere for the solution of Mg, surface grinding was performed to remove the oxide film, and the ingot was cut to a predetermined size.

[0349] Afterwards, cutting was performed by adjusting the thickness to achieve the appropriate final thickness. Each cut sample was rough rolled under the conditions listed in Tables 7 and 8. Subsequently, intermediate heat treatment was performed under conditions where the crystal grain size became approximately 30 μm through recrystallization.

[0350] Next, finish rolling (finishing process) was performed under the conditions listed in Tables 7 and 8.

[0351] Then, a mechanical surface treatment process was performed on these samples using the method described in Tables 7 and 8.

[0352] In addition, sandpaper polishing was performed using #240 abrasive paper.

[0353] Lapping treatment was performed using SiC-based abrasive grains and a cast iron lap.

[0354] Shot peening treatment was performed using stainless steel shots with a diameter of 0.2 mm at a projection speed of 10 m / sec and a projection time of 5 seconds.

[0355] Afterwards, finishing heat treatment was performed under the conditions listed in Tables 7 and 8, and materials with a thickness × width of approximately 60 mm, as listed in Tables 7 and 8, were submitted.

[0356] Regarding the obtained materials, an evaluation was conducted on the following items.

[0357] (Composition Analysis)

[0358] Measurement samples were taken from the obtained ingot, and the amount of Mg was measured by inductively coupled plasma emission spectroscopy, while the amounts of other elements were measured using a glow discharge mass spectrometer (GD-MS). In addition, measurements were taken at two points, one in the center of the sample and the other in the width direction, and the one with the higher content was taken as the content of that sample. As a result, it was confirmed that the composition was as shown in Tables 5 and 6.

[0359] (Challenge Rate)

[0360] A test specimen with a width of 10 mm × a length of 60 mm was taken from the material for characteristic evaluation, and its electrical resistance was determined using the four-terminal method. Additionally, the dimensions of the test specimen were measured using a micrometer, and its volume was calculated. Then, the conductivity was calculated from the measured electrical resistance values ​​and volume. Furthermore, the test specimen was taken such that its length direction was parallel to the rolling direction of the material for characteristic evaluation. The evaluation results are shown in Tables 7 and 8.

[0361] (KAM value)

[0362] With the rolled surface, i.e., the ND surface (Normal direction), as the observation surface, the average value of the KAM was calculated as follows using an EBSD measuring device and OIM analysis software.

[0363] Mechanical polishing was performed using water-resistant abrasive paper and diamond abrasives. Subsequently, finishing polishing was performed using a colloidal silica solution. Then, using an EBSD measurement device (Quanta FEG 450 manufactured by FEI, OIM Data Collection manufactured by EDAX / TSL (currently AMETEK)) and analysis software (OIM Data Analysis ver. 7.3.1 manufactured by EDAX / TSL (currently AMETEK)), electron beam acceleration voltage of 15 kV and 10,000 μm 2 In the above measurement area, the observation surface was measured by the EBSD method in steps of 0.25 μm intervals. The measurement results were analyzed using the data analysis software OIM to obtain the CI value for each measurement point. Excluding measurement points with a CI value of 0.1 or less, the orientation difference of each grain was analyzed using the data analysis software OIM. The boundary between adjacent measurement points where the orientation difference was 15° or more was defined as the grain boundary. Then, the average grain size A was calculated using the Area Fraction with the data analysis software OIM. Subsequently, the observation surface was measured by the EBSD method in steps of measurement intervals that were less than or equal to one-tenth of the average grain size A. To include a total of at least 1,000 grains, the total area across multiple fields of view was 10,000 μm. 2 In the measurement area exceeding the threshold, the measurement results were analyzed using the data analysis software OIM to obtain the CI value for each measurement point. Excluding measurement points with a CI value of 0.1 or less, the orientation difference of each grain was analyzed using the data analysis software OIM. The boundary between measurement points where the orientation difference between adjacent pixels (measurement points) was 5° or greater was considered as a grain boundary, and the measurement results were analyzed. Then, the KAM value for all pixels was calculated, and the average value was determined.

[0364] (Internal stress relaxation characteristics)

[0365] For the stress relaxation resistance test, stress was applied by a method based on the cantilever screw type in accordance with the Japan Copper Association Technical Standard JCBA-T309:2004, and the residual stress rate was measured after holding at a temperature of 200°C for 4 hours. The evaluation results are shown in Tables 7 and 8.

[0366] For the test method, a test specimen (width 10 mm) was taken from each material for characteristic evaluation in a direction parallel to the rolling direction, the initial bending displacement was set to 2 mm and the span length was adjusted so that the maximum surface stress of the test specimen was 80% of the yield strength. The maximum surface stress is determined by the following formula.

[0367] Maximum surface stress (MPa) = 1.5Etδ0 / L s 2

[0368] However, each symbol represents the following values.

[0369] E : Young's modulus (MPa)

[0370] t : Thickness of sample (mm)

[0371] δ0: Initial bending displacement (mm)

[0372] L s : Span length (mm)

[0373] In addition, the yield strength used here was obtained by taking a No. 13B test specimen specified in JIS Z 2241 from a material for characteristic evaluation and measuring the 0.2% yield strength by the offset method of JIS Z 2241.

[0374] Residual stress rate RS from bending marks after holding at a temperature of 200 ℃ for 4 hours G (%) was measured, and internal stress relaxation characteristics were evaluated. In addition, the residual stress rate RS G (%) was calculated using the following formula.

[0375] Residual stress rate RS G (%) = (1 - δ t / δ0) × 100

[0376] However, each symbol represents the following values.

[0377] δ t : (Permanent bending displacement after holding at 200 ℃ for 4 hours (mm)) - (Permanent bending displacement after holding at room temperature for 24 hours (mm))

[0378] δ0: Initial bending displacement (mm)

[0379] (Mechanical properties)

[0380] Test specimens of No. 13B as specified in JIS Z 2241 were taken from the material for characteristic evaluation, and the tensile strength was measured by the offset method of JIS Z 2241. In addition, the test specimens were taken in a direction parallel to the rolling direction. The evaluation results are shown in Tables 7 and 8.

[0381]

[0382]

[0383]

[0384]

[0385] Comparative Example 2-1 had a lower residual stress rate and insufficient stress relaxation resistance because the Mg content was lower than that of the second embodiment.

[0386] Comparative Example 2-2 has a Mg content that exceeds the range of the second embodiment, and the conductivity has decreased.

[0387] Comparative Examples 2-3 had a total content of S, P, Se, Te, Sb, Bi, and As exceeding 30 massppm, a low residual stress rate, and insufficient stress relaxation resistance.

[0388] Comparative Examples 2-4 had a mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] of less than 0.6, a low residual stress rate, and insufficient stress relaxation resistance.

[0389] Comparative Examples 2-5 had an average KAM value exceeding 2.4, a low residual stress rate, and insufficient stress relaxation resistance.

[0390] In this regard, it was confirmed that in Examples 2-1 to 2-23 of the present invention, conductivity and stress relaxation resistance were improved in a good balance.

[0391] Industrial applicability

[0392] The copper alloy of the present embodiment (copper alloy plastic processing material) is preferably applied to electronic and electrical equipment components such as terminals, bus bars, lead frames, and heat dissipation substrates.

Claims

Claim 1 A composition having a Mg content within the range of more than 10 massppm and less than 100 massppm, with the remainder being Cu and unavoidable impurities, wherein among the unavoidable impurities, the S content is 10 massppm or less, the P content is 10 massppm or less, the Se content is 5 massppm or less, the Te content is 5 massppm or less, the Sb content is 5 massppm or less, the Bi content is 5 massppm or less, and the As content is 5 massppm or less, and the total content of S, P, Se, Te, Sb, Bi, and As is 30 massppm or less, and when the Mg content is [Mg] and the total content of S, P, Se, Te, Sb, Bi, and As is [S + P + Se + Te + Sb + Bi + As], the mass ratio of these is [Mg] / [S + P + Se + Te + A copper alloy characterized by [Sb + Bi + As] being in the range of 0.6 to 50, having a conductivity of 97% IACS or higher, and having a residual stress rate of 20% or higher in a direction parallel to the rolling direction at 150°C and 1000 hours. Claim 2 A copper alloy according to claim 1, characterized in that the Ag content is within the range of 5 massppm or more and 20 massppm or less. Claim 3 A copper alloy according to claim 1 or 2, characterized in that among the unavoidable impurities, the content of H is 10 massppm or less, the content of O is 100 massppm or less, and the content of C is 10 massppm or less. Claim 4 A copper alloy according to claim 1 or 2, characterized in that the semi-softening temperature is 200 ℃ or higher. Claim 5 In claim 1 or 2, 10,000 μm by the EBSD method 2 In the above measurement area, the copper alloy is measured in steps of a measurement interval of 0.25 μm, and the measurement results are analyzed by the data analysis software OIM to obtain the CI value for each measurement point. Excluding measurement points with a CI value of 0.1 or less, the orientation difference of each grain is analyzed. The boundary between measurement points where the orientation difference between adjacent measurement points is 15° or more is defined as the grain boundary. The average grain size A is calculated by the Area Fraction, and the copper alloy is measured by the EBSD method in steps of measurement intervals that are less than or equal to one-tenth of the average grain size A. The total area in multiple fields of view is 10,000 μm so that a total of 1,000 or more grains are included. 2 A copper alloy characterized by having an average KAM (Kernel Average Misorientation) value of 2.4 or less when, in a measurement area, the measurement results are interpreted by data interpretation software OIM to obtain CI values ​​for each measurement point, and excluding measurement points with CI values ​​of 0.1 or less, the orientation difference of each grain is analyzed, and the boundary between measurement points where the orientation difference between adjacent pixels is 5° or more is considered as a grain boundary. Claim 6 A composition having a Mg content in the range of greater than 10 massppm and less than 100 massppm, with the remainder being Cu and unavoidable impurities, wherein among the unavoidable impurities, the S content is 10 massppm or less, the P content is 10 massppm or less, the Se content is 5 massppm or less, the Te content is 5 massppm or less, the Sb content is 5 massppm or less, the Bi content is 5 massppm or less, and the As content is 5 massppm or less, and the total content of S, P, Se, Te, Sb, Bi, and As is 30 massppm or less; wherein the Mg content is [Mg] and the total content of S, P, Se, Te, Sb, Bi, and As is [S + P + Se + Te + Sb + Bi + As], the mass ratio of these is [Mg] / [S + P + Se + Te + Sb] [+ Bi + As] is within the range of 0.6 to 50, the conductivity is 97% IACS or higher, and 10,000 µm by the EBSD method 2 In the above measurement area, the copper alloy is measured in steps with a measurement interval of 0.25 μm, and the measurement results are analyzed by the data analysis software OIM to obtain the CI value for each measurement point. Excluding measurement points with a CI value of 0.1 or less, the orientation difference of each grain is analyzed. The boundary between measurement points where the orientation difference between adjacent measurement points is 15° or more is defined as the grain boundary. The average grain size A is calculated by the Area Fraction, and the copper alloy is measured by the EBSD method in steps with a measurement interval that is 1 / 10 or less of the average grain size A. The total area in multiple fields of view is 10,000 μm so that a total of 1,000 or more grains are included. 2 A copper alloy characterized by having an average KAM (Kernel Average Misorientation) value of 2.4 or less when, in a measurement area, the measurement results are interpreted by data interpretation software OIM to obtain CI values ​​for each measurement point, and excluding measurement points with CI values ​​of 0.1 or less, the orientation difference of each grain is analyzed, and the boundary between measurement points where the orientation difference between adjacent pixels is 5° or more is considered as a grain boundary. Claim 7 A copper alloy according to claim 6, characterized in that the Ag content is within the range of 5 massppm or more and 20 massppm or less. Claim 8 In claim 6 or 7, the residual stress rate RS after holding at 200°C for 4 hours in a direction parallel to the rolling direction G A copper alloy characterized by having (%) of 20% or more. Claim 9 A copper alloy plastic material characterized by being made of the copper alloy described in claim 1 or claim 6. Claim 10 A copper alloy plastically processed material according to claim 9, characterized in that it is a rolled plate with a thickness in the range of 0.1 mm or more and 10 mm or less. Claim 11 A copper alloy plastically processed material characterized by having a Sn plating layer or an Ag plating layer on its surface in claim 9. Claim 12 A component for electronic or electrical equipment characterized by being made of a copper alloy plastically processed material as described in claim 9. Claim 13 A terminal characterized by being made of a copper alloy plastically processed material as described in claim 9. Claim 14 A bus bar characterized by being made of a copper alloy plastically processed material as described in claim 9. Claim 15 A lead frame characterized by being made of a copper alloy plastically processed material as described in claim 9. Claim 16 A heat dissipation substrate characterized by being manufactured using the copper alloy described in claim 1 or claim 6.

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