Copper alloy, copper alloy plastically working material, member for electronic / electrical equipment, member for flexible

Abstract

A copper alloy which has excellent conductivity, a low Young's modulus and a sufficiently large amount of elastic deformation, and which is less susceptible to plastic deformation even when subjected to a large deformation, the copper alloy having a composition containing 15-57 mass% of Zn and 12 mass% or less of Al, the content of the Zn being A mass% and the content of the Al being B mass%, the content of the Zn being A mass% or less and the content of the Al being B mass% or less, and the content of the Zn being A mass% or less and the content of the Al being B mass% or less. A + 5 * B > = 30 and A + 3.5 * B < = 57 are satisfied, the remainder is Cu and unavoidable impurities, the volume fraction of the [beta] phase is 50% or more, and the average value of the KAM value of the [beta] phase measured excluding a measurement point at which the CI value analyzed by data analysis software OIM is 0.1 or less is 2.0 DEG or less when measured at a measurement area of 1 mm2 or more at a step length of 1 [mu] m by an EBSD method.

Description

Technical Field

[0001] This invention relates to a copper alloy suitable for components of electrical and electronic equipment such as semiconductor components (e.g., home appliances, lead frames), printed circuit boards, heat sinks, switch components, busbars, and connectors; copper alloy plastic processing materials made of the copper alloy; components for electronic and electrical equipment; components for flexible devices; heat dissipation components; and metal sealing materials.

[0002] This application claims priority based on Japanese Patent Application No. 2023-193599, filed on November 14, 2023, the contents of which are incorporated herein by reference. Background Technology

[0003] In the past, copper or copper alloys with excellent electrical conductivity and thermal conductivity were used in electronic and electrical equipment components such as terminals, busbars, lead frames, and heat dissipation components.

[0004] Copper alloys used for the various purposes described above include, for example, Cu-Zn alloys (so-called brass) as shown in Patent Documents 1-3. In these Patent Documents 1-3, various elements other than Cu and Zn are added to ensure strength and workability.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2001-164328 (A)

[0006] Patent Document 2: Japanese Patent Application Publication No. 2002-088428 (A)

[0007] Patent Document 3: Japanese Patent Application Publication No. 2009-062610 (A)

[0008] Patent Document 4: Japanese Patent Application Publication No. 2000-169920 (A)

[0009] In recent years, efforts have been made to improve the usability of electronic and electrical equipment by promoting the flexibility of components used in these devices. Therefore, materials constituting these components are required to have a low Young's modulus to facilitate elastic deformation, and a large elastic deformation capacity to ensure they do not undergo plastic deformation and return to their original shape even under significant deformation.

[0010] In conventional copper alloys as described in Patent Documents 1-3, the Young's modulus does not decrease and the elastic deformation cannot be sufficiently increased, so plastic deformation may easily occur when subjected to large deformation.

[0011] Patent document 4 reports a copper-based alloy that, while maintaining excellent machinability, exhibits significant pseudoelastic deformation due to its shape memory and hyperelastic properties. However, the Young's modulus is not sufficiently reduced, making it difficult to deform.

[0012] Furthermore, the conductivity was not disclosed. With low conductivity, there are problems such as high heat generation and high energy loss when electricity is applied. Summary of the Invention

[0013] The present invention was made in view of the above circumstances, and its object is to provide a copper alloy with excellent electrical conductivity, low Young's modulus and large elastic deformation, which is not prone to plastic deformation even under large deformation, copper alloy plastic processing materials made of the copper alloy, components for electronic and electrical equipment, components for flexible devices, heat dissipation components and metal sealing materials.

[0014] To address the aforementioned issues, the inventors conducted in-depth research and obtained the following insights. It has become clear that, in order to obtain copper materials with low Young's modulus, it is important to "obtain a large amount of β phase" and "reduce the strain within the material".

[0015] The Young's modulus of the β phase found in copper alloys is lower than that of the α phase used in typical copper alloys. Therefore, the Young's modulus can be reduced by obtaining a large amount of β phase. Moreover, by reducing the strain within the β phase, deformation within the β phase is not hindered, resulting in an even lower Young's modulus.

[0016] Furthermore, by making the strain distribution within the material uniform and eliminating parts that are difficult to deform locally, the material can be deformed uniformly as a whole, thereby obtaining a lower Young's modulus.

[0017] It is clear from the above that in order to reduce the Young's modulus of copper alloys, it is important to obtain a large amount of β phase with small strain and uniform dispersion.

[0018] This invention is based on the above-mentioned insights. A copper alloy of aspect 1 of this invention is characterized in that the copper alloy has the following composition: containing 15% by mass and 57% by mass of Zn, containing 12% by mass of Al, wherein when the Zn content is set as A% by mass and the Al content as B% by mass, A+5×B≥30 and A+3.5×B≤57 are satisfied, the remainder is Cu and unavoidable impurities, the volume fraction of the β phase is 50% or more, and the composition is determined by EBSD method with a step size of 1 μm for 1 mm. 2 The above measurement areas were measured, and the average value of the KAM (Kernel Average Misorientation) of the β phase measured was 2.0° or less, excluding measurement points with a CI value of less than 0.1 as analyzed by the data analysis software OIM.

[0019] According to aspect 1 of the present invention, the copper alloy comprises: 15% by mass and 57% by mass of Zn, 12% by mass and 12% by mass of Al, wherein when the Zn content is set as A% by mass and the Al content is set as B% by mass, A+5×B≥30 and A+3.5×B≤57 are satisfied, and the remainder is Cu and unavoidable impurities. Therefore, it exhibits excellent strength and electrical conductivity, and also possesses good thermal conductivity. Furthermore, the β phase can be sufficiently formed.

[0020] Furthermore, the volume fraction of the β phase is over 50%, and the average KAM value of the β phase is below 2.0°. Therefore, the β phase accounts for a large proportion and the strain is sufficiently low, resulting in a sufficiently low Young's modulus and easy elastic deformation. As a result, the amount of elastic deformation is sufficiently increased, and even under large deformation, plastic deformation is not easily induced, making it suitable for applications requiring flexibility.

[0021] The copper alloy of aspect 2 of the present invention is characterized in that, in the copper alloy of aspect 1 of the present invention, it further comprises 0.005% by mass or more and 10% by mass or less of Ni.

[0022] According to aspect 2 of the present invention, the copper alloy contains 0.005% by mass and 10% by mass of Ni, and therefore its strength can be further improved by Ni-based solid solution strengthening and the generation of precipitates containing Ni and Al.

[0023] The copper alloy of aspect 3 of the present invention is characterized in that, in the copper alloy of aspect 1 or aspect 2 of the present invention, it further comprises one or more elements selected from group C of Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As and Ag in a total range of 0.0005% by mass or more and 2.5% by mass or less.

[0024] According to aspect 3 of the present invention, the copper alloy contains one or more elements selected from the group C of Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As and Ag in a total range of 0.0005% by mass or more and 2.5% by mass or less. Therefore, it is possible to suppress plastic deformation of the β phase while maintaining conductivity and further increase the amount of elastic deformation.

[0025] The copper alloy of aspect 4 of the present invention is characterized in that, in the copper alloy of any of aspects 1 to 3 of the present invention, it further comprises one or more group D elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C and mixed rare earth metals (MM) in a total range of 0.0005% by mass or more and 2.5% by mass or less.

[0026] According to aspect 4 of the present invention, the copper alloy contains one or more D group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C and mixed rare earth metals (MM) in a total range of 0.0005% by mass or more and 2.5% by mass or less. Therefore, it is possible to suppress plastic deformation of the β phase while maintaining conductivity and further increase the amount of elastic deformation.

[0027] The copper alloy of aspect 5 of the present invention is characterized in that, in the copper alloy of any one of aspects 1 to 4 of the present invention, the standard deviation of the KAM value of the β phase is less than 0.75°.

[0028] According to aspect 5 of the invention, the standard deviation of the KAM value of the β phase is less than 0.75°, so the strain is not localized and the deformation is not hindered by the strain, thus reliably reducing the Young's modulus.

[0029] The copper alloy of aspect 6 of the present invention is characterized in that, in the case of the copper alloy of any of aspects 1 to 5 of the present invention, the average value of the KAM value of the α phase is 2.0° or less.

[0030] According to aspect 6 of the invention, the copper alloy sometimes has an α phase in addition to the β phase, but since the average KAM value of the α phase is less than 2.0°, the strain is sufficiently small, and the Young's modulus can be controlled to be low.

[0031] The copper alloy of aspect 7 of the present invention is characterized in that, in the copper alloy of any of aspects 1 to 6 of the present invention, the average value of the GOS (Grain Orientation Spread) value of the β phase is 2.0° or less.

[0032] According to aspect 7 of the present invention, the average value of the GOS value of the β phase is less than 2.0°, the strain is not localized, and the Young's modulus can be controlled to be even lower.

[0033] The copper alloy of aspect 8 of the present invention is characterized in that, in the copper alloy of any one of aspects 1 to 7 of the present invention, the Young's modulus is 100 GPa or less.

[0034] According to aspect 8 of the present invention, the copper alloy has a Young's modulus of less than 100 GPa, which is sufficiently low and allows for easy elastic deformation, thus making it suitable for applications requiring flexibility.

[0035] The copper alloy of aspect 9 of the present invention is characterized in that, in the copper alloy of any one of aspects 1 to 8 of the present invention, the maximum elastic strain is 0.4% or more.

[0036] According to aspect 9 of the present invention, the copper alloy has a maximum elastic strain of 0.4% or more and is not prone to plastic deformation even under large deformation.

[0037] The copper alloy of aspect 10 of the present invention is characterized in that, in the copper alloy of any one of aspects 1 to 9 of the present invention, the conductivity is 10% IACS or higher.

[0038] According to aspect 10 of the present invention, the copper alloy has a conductivity of 10% IACS or higher, thus ensuring conductivity and making it suitable as a material for use as an electrically conductive component.

[0039] The copper alloy plastic processing material of aspect 11 of the present invention is characterized in that it is composed of a copper alloy of any one of aspects 1 to 10 of the present invention.

[0040] The component for electronic and electrical equipment of aspect 12 of the present invention is characterized in that it is made of a copper alloy of any one of aspects 1 to 10 of the present invention.

[0041] The flexible device component of aspect 13 of the present invention is characterized in that it is made of a copper alloy of any one of aspects 1 to 10 of the present invention.

[0042] The heat dissipation component of aspect 14 of the present invention is characterized in that it is made of a copper alloy of any one of aspects 1 to 10 of the present invention.

[0043] The metal sealing material of aspect 15 of the present invention is characterized in that it is composed of a copper alloy of any one of aspects 1 to 10 of the present invention.

[0044] According to the present invention, it is possible to provide a copper alloy with excellent electrical conductivity, low Young's modulus, and sufficiently large elastic deformation, which is not prone to plastic deformation even under large deformation; a copper alloy plastic processing material made of the copper alloy; a component for electronic and electrical equipment; a component for flexible devices; a component for heat dissipation; and a metal sealing material. Attached Figure Description

[0045] Figure 1 This is a flowchart of the copper alloy manufacturing method according to this embodiment.

[0046] Figure 2 This is an explanatory diagram of the maximum elastic strain in the embodiment. Detailed Implementation

[0047] The following describes a copper alloy according to one embodiment of the present invention. Furthermore, the copper alloy of this embodiment can be used as a material for various components such as parts for electronic and electrical equipment, parts for flexible devices, heat dissipation components, and metal sealing materials.

[0048] The copper alloy of this embodiment has the following composition: containing 15% by mass and 57% by mass of Zn, containing 12% by mass and 12% by mass of Al, wherein when the content of Zn is set as A% by mass and the content of Al is set as B% by mass, A+5×B≥30 and A+3.5×B≤57 are satisfied, and the remaining part is Cu and unavoidable impurities.

[0049] Furthermore, the copper alloy of this embodiment may further contain 0.005% by mass and 10% by mass of Ni.

[0050] Furthermore, in the copper alloy of this embodiment, one or more elements selected from the group C of Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As and Ag may be included in a total range of 0.0005% by mass or more and 2.5% by mass or less.

[0051] Furthermore, in the copper alloy of this embodiment, one or more group D elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C and mixed rare earth metals (MM) may be further included in a total range of 0.0005% by mass or more and 2.5% by mass or less.

[0052] Furthermore, in the copper alloy of this embodiment, the volume fraction of the β phase is 50% or more, and the β phase is measured by the EBSD method with a step size of 1 μm for 1 mm. 2 The above measurement areas were used to measure the average KAM (Kernel Average Misorientation) value of the β phase measured at measurement points with a CI value of less than 0.1 as analyzed by the data analysis software OIM. The average value of the KAM value was less than 2.0°.

[0053] Furthermore, in the copper alloy of this embodiment, the standard deviation of the KAM value of the β phase is preferably 0.75° or less.

[0054] Furthermore, in the copper alloy of this embodiment, it is preferable that the average value of the GOS (Grain Orientation Spread) value of the β phase is 2.0° or less.

[0055] Furthermore, in the copper alloy of this embodiment, when an α phase is present, it is preferable that the average value of the KAM value of the α phase is 2.0° or less. Also, it is preferable that the standard deviation of the KAM value of the α phase is 0.75° or less.

[0056] In this embodiment, the copper alloy preferably has a Young's modulus of 100 GPa or less.

[0057] Furthermore, in the copper alloy of this embodiment, the maximum elastic strain is preferably 0.4% or more.

[0058] Furthermore, in the copper alloy of this embodiment, a conductivity of 10% IACS or higher is preferred.

[0059] The reasons for specifying the composition, crystal structure, and various properties of the copper alloy in this embodiment as described above will be explained below.

[0060] (Zn)

[0061] The copper alloy of this embodiment is mainly composed of Cu and Zn. Here, if the Zn content is less than 15% by mass, the β phase will not be sufficiently present, and the volume fraction of the β phase will be less than 50%, potentially leading to an increase in Young's modulus. Furthermore, if the Zn content exceeds 57% by mass, a very brittle γ phase will appear, resulting in a significant reduction in machinability.

[0062] Therefore, in this embodiment, the Zn content is set within the range of 15% by mass or more and 57% by mass or less. This results in excellent strength, electrical conductivity, and good thermal conductivity.

[0063] Here, the Zn content is preferably 18% by mass or more, more preferably 20% by mass or more. Furthermore, the Zn content is preferably 56% by mass or less, more preferably 55% by mass or less.

[0064] (Al)

[0065] The strength can be further improved by adding an appropriate amount of Al to Cu-Zn alloys.

[0066] Here, in order to suppress the brittle γ phase and ensure sufficient β phase, the Al content is set to 12% by mass or less, and when the Zn content is set to A% by mass and the Al content to B% by mass, the following conditions must be met: A + 5 × B ≥ 30 and A + 3.5 × B ≤ 57. When A + 5 × B is less than 30, sufficient β phase cannot be obtained, leading to an increase in Young's modulus. When A + 3.5 × B exceeds 57, the proportion of the brittle γ phase increases, making it difficult to process.

[0067] Furthermore, the Al content is more preferably 11% by mass or less, more preferably 10% by mass or less. Moreover, the Al content is more preferably 0.005% by mass or more, more preferably 0.01% by mass or more.

[0068] Furthermore, A+5×B is more preferably 31 or more, and more preferably 32 or more.

[0069] Furthermore, A+3.5×B is more preferably 56 or less, and more preferably 55 or less.

[0070] (Ni)

[0071] By adding an appropriate amount of Ni to Cu-Zn alloys, in addition to solid solution strengthening, it can also be added together with Al to produce precipitates containing Ni and Al, thereby achieving further improvement in strength.

[0072] In order to achieve the effect of increasing strength based on Ni without significantly reducing conductivity, it is preferable to set the Ni content in the range of 0.005% by mass or more and 10% by mass or less.

[0073] Furthermore, the Ni content is more preferably 0.01% by mass or more, and more preferably 0.1% by mass or more. Additionally, the Ni content is more preferably 9% by mass or less, and more preferably 8% by mass or less.

[0074] Furthermore, without the intentional addition of Ni, the Ni content can be less than 0.005 by mass.

[0075] (Group C elements: selected from one or more of Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, and Ag)

[0076] In the copper alloy of this embodiment, by including one or more C group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, and Ag, the plastic deformation of the β phase is suppressed, and the elastic deformation is further increased. On the other hand, if these C group elements are included in large quantities, the electrical conductivity may decrease.

[0077] Therefore, in the copper alloy of this embodiment, it is preferable that the content of one or more C group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As and Ag is set in a range of 0.0005% by mass or more and 2.5% by mass or less.

[0078] Co, Fe, Sn, Mg, and Ag are suitable elements for strengthening the β phase, with an optimal combined composition of 0.0005% to 1% by mass. Mn, Si, and Be are effective elements that, in addition to strengthening the β phase, also contribute to obtaining more of the β phase, with an optimal combined composition of 0.0005% to 1% by mass. Sb, Cd, and As are suitable elements for strengthening the β phase, with an optimal combined composition of 0.0005% to 0.5% by mass.

[0079] Furthermore, the total content of elements in group C is preferably 0.001% by mass or more, more preferably 0.005% by mass or more. Moreover, the total content of elements in group C is preferably 2.0% by mass or less, more preferably 1.5% by mass or less.

[0080] Furthermore, without the intentional addition of elements from group C, the total content of elements from group C can be less than 0.0005 by mass.

[0081] (Group D elements: selected from one or more of Ti, V, Cr, Nb, Mo, W, P, Zr, B, C and MM)

[0082] In the copper alloy of this embodiment, by including one or more D-group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, and MM, precipitates or compounds are formed, thereby suppressing the plastic deformation of the β phase and further increasing the elastic deformation. On the other hand, if these D-group elements are included in large quantities, the electrical conductivity may decrease.

[0083] Therefore, in the copper alloy of this embodiment, it is preferable that the content of one or more D group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C and MM is set in a range of 0.0005% by mass or more and 2.5% by mass or less.

[0084] Ti, V, Cr, Zr, and MM are elements suitable for forming compounds with oxygen, sulfur, P, B, and C in materials to strengthen the β phase, with an optimal combined composition of 0.0005% to 0.8% by mass. Nb, Mo, and W are elements suitable for strengthening the β phase, with an optimal combined composition of 0.0005% to 0.5% by mass. P and C are elements suitable for forming compounds with other elements to strengthen the β phase, in addition to deoxidation of the material, with an optimal combined composition of 0.0005% to 1% by mass. B is an element suitable for forming compounds with other elements to strengthen the β phase, in addition to inhibiting embrittlement of the material, with an optimal composition of 0.0005% to 1% by mass.

[0085] Furthermore, the total content of elements in group D is preferably 0.001% by mass or more, more preferably 0.005% by mass or more. Moreover, the total content of elements in group D is preferably 2.0% by mass or less, more preferably 1.5% by mass or less.

[0086] Furthermore, without the intentional addition of elements from group D, the total content of elements from group D can be less than 0.0005 by mass.

[0087] In addition to the elements mentioned above, unavoidable impurities include Ba, Ca, rare earth elements, Ta, Re, Ru, Sr, Os, Rh, Ir, Pb, Pd, Pt, Au, Hf, Hg, Ga, In, Ge, Tl, N, and Li. These impurity elements can be included within a range that does not affect the properties.

[0088] Since these unavoidable impurities may reduce conductivity, the total amount is preferably 2.5% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.5% by mass or less.

[0089] (Volume fraction of β phase)

[0090] In Cu-Zn alloys, in addition to the β phase, α and γ phases may also appear. Here, due to the deformation of the β phase, the Young's modulus decreases. Therefore, when the volume fraction of the β phase is less than 50%, the β phase cannot be fully deformed, resulting in an increase in the Young's modulus.

[0091] Therefore, in the copper alloy of this embodiment, the volume fraction of the β phase is set to 50% or more.

[0092] In addition, the volume fraction of the β phase is preferably 60% or more, and more preferably 70% or more.

[0093] Although there are no specific limitations, the volume fraction of the β phase can be less than 100%, less than 98%, or less than 95%.

[0094] (Average KAM values ​​of the β phase)

[0095] The KAM (Kernel Average Misorientation) value, determined by EBSD, is calculated by averaging the orientation differences between a pixel and its surrounding pixels. Since pixels are hexagonal in shape, the average of the orientation differences with the six nearest neighbor pixels is calculated as the KAM value, with the nearest neighbor order set to 1. Using this KAM value, the local orientation difference, i.e., the strain distribution, can be visualized. The less strain within the material, the weaker the resistance to strain-induced deformation, and the lower the Young's modulus.

[0096] Therefore, the average value of the KAM value of the β phase is preferably 2.0° or less, more preferably 1.75° or less, and even more preferably 1.50° or less.

[0097] Although there are no specific limitations, the average value of the KAM value of the β phase can be above 0.01°, above 0.10°, or above 0.20°.

[0098] (Standard deviation of KAM values ​​for the β phase)

[0099] If strain is localized, the standard deviation of the aforementioned KAM values ​​increases. In regions of strain localization, deformation is hindered by strain, thus leading to an increase in Young's modulus.

[0100] Therefore, the standard deviation of the KAM value of the β phase is preferably 0.75° or less, more preferably 0.65° or less, and even more preferably 0.6° or less.

[0101] Although there are no specific limitations, the standard deviation of the KAM value of the β phase can be greater than 0.01°, greater than 0.03°, or greater than 0.05°.

[0102] (Average GOS values ​​of the β phase)

[0103] The GOS (grain orientation spread) value, measured by EBSD, is calculated by: taking the average angular difference θ between each pixel in the crystal, then calculating the difference between each pixel and the average θ, and finally averaging these differences for all pixels within the grain. This average value is the GOS value. Here, the average value is calculated using the number of crystals, not the size of the region in each crystal. This indicates that a large GOS value suggests localized strain within the grain. Therefore, a high GOS value, meaning non-uniform strain, creates areas difficult to deform locally, thus increasing the Young's modulus.

[0104] Therefore, the average GOS value of the β phase is preferably 2.0° or less, more preferably 1.75° or less, and even more preferably 1.50° or less. Furthermore, the average value is calculated using the number of grains.

[0105] Although there are no specific limitations, the average GOS value of the β phase can be greater than 0.01°, greater than 0.10°, or greater than 0.15°.

[0106] (Average and standard deviation of KAM values ​​for the α phase)

[0107] In the copper alloy of this embodiment, an α phase is sometimes present in addition to the β phase. When an α phase is present, it is preferable that the strain in this α phase is also low. Furthermore, it is preferable that the strain is not localized in the α phase.

[0108] Therefore, the average value of the KAM value of the α phase is preferably 2.0° or less, more preferably 1.75° or less, and even more preferably 1.50° or less.

[0109] Although there are no specific limitations, the average value of the KAM value of the α phase can be above 0.01°, above 0.10°, or above 0.20°.

[0110] Furthermore, the standard deviation of the KAM value of the α phase is preferably 0.75° or less, more preferably 0.65° or less, and even more preferably 0.6° or less.

[0111] Although there are no specific limitations, the standard deviation of the KAM value of the α phase can be greater than 0.01°, greater than 0.03°, or greater than 0.05°.

[0112] (Young's modulus)

[0113] In the copper alloy of this embodiment, a low Young's modulus is required so that it can easily undergo elastic deformation.

[0114] Specifically, in the copper alloy of this embodiment, the Young's modulus is preferably 100 GPa or less.

[0115] Furthermore, the Young's modulus is preferably below 90 GPa, and more preferably below 80 GPa.

[0116] Although there are no specific limitations, the Young's modulus can be above 10 GPa, above 15 GPa, or above 20 GPa.

[0117] (Maximum elastic strain)

[0118] In the copper alloy of this embodiment, it is required to ensure the amount of elastic deformation so that it is not prone to plastic deformation even when subjected to large deformation.

[0119] Specifically, in the copper alloy of this embodiment, the maximum elastic strain is preferably 0.4% or more.

[0120] Furthermore, the maximum elastic strain is preferably 0.45% or more, and more preferably 0.5% or more.

[0121] Although there are no specific limitations, the maximum elastic strain can be below 8%, below 6.5%, or below 5.5%.

[0122] (Conductivity)

[0123] In the copper alloy of this embodiment, when the conductivity is 10% IACS or higher, it is particularly suitable as a material for the energized component of electrical and electronic equipment.

[0124] Furthermore, the conductivity of the copper alloy in this embodiment is preferably 12% IACS or higher, and more preferably 14% IACS or higher.

[0125] Although there are no particular limitations, the conductivity of the copper alloy in this embodiment can be 80% IACS or less, 70% IACS or less, or 60% IACS or less.

[0126] Next, refer to Figure 1 The flowchart shown illustrates an example of a method for manufacturing the copper alloy of this embodiment.

[0127] (Smelting / casting process S01)

[0128] First, the aforementioned elements are added to the copper molten liquid obtained by smelting oxygen-free copper raw materials to adjust the composition, thereby producing a copper alloy molten liquid. Furthermore, elemental elements, master alloys, etc., can be used when adding various elements. The raw materials containing the aforementioned elements can be smelted together with the copper raw materials. Here, each element is preferably a so-called 3N with a purity of 99.9% by mass or higher, or a so-called 4N with a purity of 99.99% by mass or higher. In the smelting process, to reduce the hydrogen concentration, it is preferable to use an inert gas atmosphere (e.g., Ar gas) with low vapor pressure of H2O for atmosphere smelting, and the holding time during smelting is kept to a minimum. Then, the composition-adjusted copper alloy molten liquid is poured into a mold to produce an ingot. Furthermore, considering mass production, continuous casting or semi-continuous casting methods are preferred.

[0129] (Hot working process S02)

[0130] To introduce strain and deform the shape to a specified size, the obtained ingot is hot-worked. During hot working, by introducing strain, high strain can be applied in a coarse-grained state, thus improving the uniformity of the material.

[0131] In the hot working process S02, it is necessary to destroy the casting structure, so a certain processing rate is required. The total processing rate needs to be set to 50% or more, preferably 55% or more, and even more preferably 60% or more.

[0132] Furthermore, there are no particular limitations on the plastic forming method, but rolling is preferred when the final shape is sheet or strip. Extrusion or die rolling is preferred when the final shape is wire or bar, and forging or stamping is preferred when the final shape is block.

[0133] (Warm processing step S03)

[0134] Next, in order to introduce strain and deform the shape to the specified size while the phase transformation occurs, the obtained hot-working material is subjected to warm working.

[0135] In this warm processing step S03, within a temperature range of 200°C to 600°C where the α+β phase is stable and sufficient diffusion rate can be obtained, the average processing rate per pass is set to 20% or less and multiple processing operations are performed, thereby preferentially applying strain to the easily deformable β phase.

[0136] Furthermore, the total processing rate in the warm processing step S03 needs to be set to 20% or more, preferably 25% or more, and even more preferably 30% or more.

[0137] Furthermore, there are no particular limitations on the plastic forming method, but rolling is preferred when the final shape is sheet or strip. Extrusion or die rolling is preferred when the final shape is wire or bar, and forging or stamping is preferred when the final shape is block.

[0138] (First heat treatment process S04)

[0139] Next, in order to homogenize and / or dissolve, and to induce recrystallization while precipitating fine α phase to obtain a uniformly dispersed β phase, heat treatment is performed in the temperature range of α+β phase.

[0140] The heat treatment method is not particularly limited, but it is preferred to be carried out in a non-oxidizing or reducing atmosphere.

[0141] Furthermore, the heat treatment temperature needs to be below 600°C, preferably below 550°C. On the other hand, if the temperature becomes too low, diffusion will be insufficient, so it needs to be set to 350°C or higher.

[0142] Furthermore, the cooling method after heat treatment is implemented by water quenching or other methods with a cooling rate of 200°C / min or higher.

[0143] In addition, the warm working process S03 and the first heat treatment process S04 can be repeated multiple times.

[0144] (Cold processing step S05)

[0145] After the first heat treatment step S04, cold working is performed. The working temperature is in the range of -200°C to 400°C. Furthermore, the total machining rate is 30% or more, and a uniform strain distribution is obtained by applying high strain.

[0146] Furthermore, there are no particular limitations on the processing method in this cold working step S05; for example, rolling, drawing, extrusion, die rolling, forging, stamping, etc., can be used. In this embodiment, drawing is performed.

[0147] (Second heat treatment process S06)

[0148] Next, in order to form a large amount of β phase, the cold-worked material is heat-treated. For cold-worked materials subjected to high strain, by slowing down the heating rate and accelerating the cooling rate under high temperature conditions, the proportion of β phase can be increased, and the microstructure with an average KAM value of β phase below 2.0° can be frozen.

[0149] The heat treatment method is not particularly limited, but it is preferred to be carried out in a non-oxidizing or reducing atmosphere.

[0150] Furthermore, the heat treatment needs to be performed at a high temperature. At low temperatures, a sufficient amount of β phase cannot be obtained; therefore, the heat treatment temperature is preferably 600°C or higher, more preferably 700°C or higher. On the other hand, if the heat treatment temperature becomes too high, it will exceed the melting point of the material; therefore, the heat treatment temperature needs to be set below 1000°C.

[0151] Furthermore, the heating rate needs to be slow, below 10℃ / min. By slowing down the heating rate, tissues with an average KAM value of less than 2.0 in the β phase can be obtained.

[0152] On the other hand, the cooling method needs to employ a cooling rate of 200°C / min or higher, such as water quenching. With a slow cooling rate, a large number of phases other than the β phase may appear during the cooling process, potentially reducing the proportion of the β phase.

[0153] In addition, to improve the efficiency of rough machining and to achieve a more uniform microstructure, hot working can be performed after heat treatment.

[0154] (Tempering and conditioning process S07)

[0155] To adjust the material strength, recrystallized heat-treated copper can be quenched and tempered. If lower material strength is required, quenching and tempering can be omitted. There are no particular limitations on the final thickness or wire diameter.

[0156] In addition, there are no special restrictions on the processing method in the heat treatment process S07. For example, rolling, drawing, extrusion, die rolling, forging, stamping, etc. can be used.

[0157] The copper alloy (copper alloy plastic processing material) of this embodiment is manufactured through the process described above.

[0158] Furthermore, the method of adjusting the volume fraction of the β phase or the average value of KAM within the above range is not limited to a specific method. For example, it can be achieved by controlling the temperature of the warm processing step S03, the temperature of the second heat treatment step S06, the heating rate, the cooling temperature, etc., as described above.

[0159] According to the copper alloy of this embodiment having the above-described structure, it has the following composition: containing 15% by mass and 57% by mass of Zn, containing 12% by mass and 12% by mass of Al, and when the content of Zn is set as A% by mass and the content of Al is set as B% by mass, it satisfies A+5×B≥30 and A+3.5×B≤57, with the remainder being Cu and unavoidable impurities. Therefore, it has excellent strength and electrical conductivity, and can also have good thermal conductivity.

[0160] Furthermore, the volume fraction of the β phase is over 50%, and the average KAM value of this β phase is below 2.0°. Therefore, the β phase accounts for a large proportion and the strain is sufficiently low, resulting in a sufficiently low Young's modulus and easy elastic deformation. As a result, the amount of elastic deformation is sufficiently increased, and even under large deformation, plastic deformation is not easily induced, making it suitable for applications requiring flexibility.

[0161] In this embodiment, the strength can be further improved by further including 0.005% by mass and 10% by mass of Ni.

[0162] In this embodiment, when the total content is 0.0005% by mass or more and 2.5% by mass or less, and further includes one or more C group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As and Ag, it is possible to maintain conductivity while suppressing plastic deformation of the β phase and further increasing elastic deformation.

[0163] In this embodiment, when the total content is 0.0005% by mass or more and 2.5% by mass or less, and further includes one or more D group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C and MM, it is possible to maintain conductivity while suppressing plastic deformation of the β phase and further increasing elastic deformation.

[0164] In this embodiment, when the standard deviation of the KAM value of the β phase is less than 0.75°, the strain is not localized, and deformation is not hindered by strain, thus reliably reducing the Young's modulus. This further increases the amount of elastic deformation, making it less prone to plastic deformation even under large deformations, and suitable for applications requiring flexibility.

[0165] In this embodiment, an α phase is present, and when the average KAM value of the α phase is 2.0° or less, an α phase is present in addition to the β phase. However, since the average KAM value of the α phase is 2.0° or less, the strain is sufficiently small, and the Young's modulus can be controlled to be low. As a result, the elastic deformation is further increased, and plastic deformation is not easily caused even under large deformation, making it suitable for applications requiring flexibility.

[0166] In this embodiment, when the average value of the β phase GOS (Grain Orientation Spread) is below 2.0°, the strain is not localized, and the Young's modulus can be controlled to be low. This further increases the amount of elastic deformation, making it less prone to plastic deformation even under large deformations, thus making it suitable for applications requiring flexibility.

[0167] In this embodiment, when the maximum elastic strain is 0.4% or more, the amount of elastic deformation is sufficiently ensured, and plastic deformation is not easily caused even when subjected to large deformation, making it suitable for applications requiring flexibility.

[0168] In this embodiment, when the Young's modulus is below 100 GPa, the Young's modulus is sufficiently low, allowing for easy elastic deformation, making it suitable for applications requiring flexibility, such as flexible devices or printed wiring used in them, and metal sealing materials.

[0169] In this embodiment, the conductivity is ensured to be 10% IACS or higher, making the material suitable for use as a component in electronic and electrical equipment such as a terminal or energized part, probe, thermal interface material, heat dissipation part, etc.

[0170] The copper alloy according to embodiments of the present invention has been described above, but the present invention is not limited thereto, and appropriate modifications can be made without departing from the technical concept of the present invention. In the above embodiments, an example of a method for manufacturing the copper alloy has been described, but the method for manufacturing the copper alloy is not limited to the method described in the above embodiments, and existing manufacturing methods can be appropriately selected for manufacturing.

[0171] Example

[0172] The results of the confirmation experiments conducted to verify the effectiveness of the present invention will be described below.

[0173] First, raw materials consisting of pure copper with a purity of 99.999% by mass or higher and various additive elements with a purity of 99.9% or higher were prepared and placed in a high-purity graphite crucible. High-frequency melting was then carried out in an atmosphere furnace under an Ar gas atmosphere. The resulting composition was prepared as shown in Table 1 and then poured into an insulating material (Iso wool) mold to produce an ingot. The ingot's size was approximately 100 mm in diameter and approximately 150–200 mm in length.

[0174] Next, the obtained ingot was hot-processed (hot extrusion) in an Ar gas atmosphere under the conditions shown in Table 2.

[0175] Surface turning is performed to remove the oxide film on the surface after heat treatment, and the material is machined to a specified size. Then, the dimensions are adjusted appropriately to achieve the final shape.

[0176] Then, under the conditions shown in Table 2, warm working, primary heat treatment, cold working, secondary heat treatment, and quenching and tempering were performed to manufacture characteristic evaluation wires made of copper alloys of the present invention and comparative examples with a final wire diameter of 1 mm to 5 mm.

[0177] The copper alloys of the present invention and comparative examples obtained in the above manner were evaluated as follows. The evaluation results are shown in Table 3.

[0178] (Composition Analysis)

[0179] Test samples were collected from the obtained ingots and measured using inductively coupled plasma atomic emission spectrometry (ICP).

[0180] (Volume fraction of β phase)

[0181] A 10 mm sample was cut from the wire used for characteristic evaluation. The cross-section perpendicular to the machining direction was mechanically polished using water-resistant sandpaper and diamond abrasive, followed by fine polishing with colloidal silica solution. For this sample, an EBSD measurement device (FEI Quanta FEG 450, EDAX / TSL (now AMETEK, Inc.) OIM Data Collection) and analysis software (EDAX / TSL (now AMETEK, Inc.) OIM Data Analysis ver. 8.6) were used, with an electron beam accelerating voltage of 15 kV, a measurement interval of 1 μm, and a measurement depth of 1 mm. 2 Under the above conditions of measured area, the orientation difference of each grain is analyzed and the crystal phase is identified after excluding the measurement points with CI value below 0.1. The proportion of the area identified as β phase in each measurement field of view is set as the area ratio of β phase, and the average area ratio of three or more fields of view is taken as the volume fraction of β phase.

[0182] (KAM value, GOS value)

[0183] Similar to the method described above for the volume fraction of the β phase, the KAM values ​​of all pixels in the β phase were analyzed using an EBSD measurement device and analysis software, and the average value and standard deviation were calculated. Furthermore, the average GOS value was also calculated.

[0184] In addition, when the α phase exists, the KAM values ​​of all pixels are also calculated for the α phase, and the average value and standard deviation are calculated.

[0185] (Conductivity)

[0186] A 60mm long test piece was taken from the wire used for performance evaluation, and its resistance was determined using the four-terminal method. Furthermore, the dimensions of the test piece were measured using a micrometer, and its volume was calculated. Then, the conductivity was calculated based on the measured resistance and volume. The test piece was taken with its length parallel to the processing direction of the wire used for performance evaluation.

[0187] (Young's modulus)

[0188] Regarding Young's modulus E, a contact extensometer was installed on the aforementioned test piece, and mechanical testing was conducted according to JIS Z 2241. The modulus was then determined based on the slope of the elastic region of the stress-elongation curve. The strain rate was 5 × 10⁻⁶. -4 s -1 .

[0189] (Maximum elastic strain)

[0190] In the same tensile test as described above, such as Figure 2 As shown, stress is repeatedly applied and unloaded by increasing the applied strain by 0.5% each time. The difference between the applied strain and the residual strain at the first occurrence of residual strain during unloading is set as the maximum elastic strain.

[0191] Maximum elastic strain = Loaded strain - Residual strain

[0192] [Table 1]

[0193]

[0194] [Table 2]

[0195]

[0196] [Table 3]

[0197]

[0198] In Comparative Example 1, the composition was inappropriate, with a β phase volume fraction of 0%, a high Young's modulus of 110 GPa, and a low maximum elastic strain of 0.1%.

[0199] In Comparative Example 2, the composition was inappropriate and the volume fraction of the β phase was 0%, the Young's modulus was high at 115 GPa, and the maximum elastic strain was small at 0.1%.

[0200] In Comparative Example 3, the volume fraction of the β phase was 45%, the average KAM value of the β phase was 2.12°, the Young's modulus was relatively high at 120 GPa, and the maximum elastic strain was relatively small at 0.2%.

[0201] In Comparative Example 4, the volume fraction of the β phase was 70%, but the average KAM value of the β phase was 2.11°, the Young's modulus was high at 112 GPa, and the maximum elastic strain was small at 0.3%.

[0202] In Comparative Example 5, the volume fraction of the β phase was 95%, but the average KAM value of the β phase was 2.33°, the Young's modulus was relatively high at 105 GPa, and the maximum elastic strain was relatively small at 0.3%.

[0203] In Comparative Examples 6, 7, and 8, A+3.5×B exceeded 57, resulting in poor processability and making it impossible to prepare wires for characteristic evaluation.

[0204] In contrast, in Examples 1-17 of this invention, the volume fraction of the β phase is 50% or more, the average KAM value of the β phase is 2.0° or less, the maximum elastic strain is relatively large, and it is 0.4% or more. Furthermore, the conductivity is 10% IACS or more, exhibiting excellent conductivity.

[0205] The results of the above-mentioned experiments confirm that, according to the present invention, a copper alloy with excellent electrical conductivity, low Young's modulus, sufficiently large elastic deformation, and is not prone to plastic deformation even under large deformation conditions can be provided.

[0206] Industrial availability

[0207] According to the present invention, a copper alloy with excellent electrical conductivity, low Young's modulus, and sufficiently large elastic deformation can be provided, which is not prone to plastic deformation even under large deformation.

Claims

1. A copper alloy, characterized in that, The copper alloy has the following composition: containing 15% by mass and 57% by mass of Zn, containing 12% by mass and 12% by mass of Al, wherein when the Zn content is set as A% by mass and the Al content is set as B% by mass, A+5×B≥30 and A+3.5×B≤57, the remainder being Cu and unavoidable impurities. The volume fraction of the β phase is over 50%. The EBSD method was used to determine the step size of 1 mm with a step size of 1 μm. 2 The above measurement areas were measured, excluding measurement points with a CI value of less than 0.1 as analyzed by the data analysis software OIM. The average value of the nuclear average orientation difference KAM value of the β phase measured was less than 2.0°.

2. The copper alloy according to claim 1, characterized in that, It further contains 0.005% by mass and less than 10% by mass of Ni.

3. The copper alloy according to claim 1 or 2, characterized in that, The content further includes one or more C group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As and Ag, within a range of more than 0.0005% by mass and less than 2.5% by mass.

4. The copper alloy according to claim 1 or 2, characterized in that, The content further includes one or more group D elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C and mixed rare earth metals, within a range of more than 0.0005% by mass and less than 2.5% by mass.

5. The copper alloy according to claim 1, characterized in that, The standard deviation of the KAM value of the β phase is below 0.75°.

6. The copper alloy according to claim 1 or 2, characterized in that, In the case of an α phase, the average KAM value of the α phase is below 2.0°.

7. The copper alloy according to claim 1 or 2, characterized in that, The average GOS value of the grain orientation distribution of the β phase is below 2.0°.

8. The copper alloy according to claim 1 or 2, characterized in that, The Young's modulus is below 100 GPa.

9. The copper alloy according to claim 1 or 2, characterized in that, The maximum elastic strain is above 0.4%.

10. The copper alloy according to claim 1 or 2, characterized in that, The conductivity is above 10% IACS.

11. A copper alloy plastic processing material, characterized in that, It is composed of the copper alloy as described in claim 1 or 2.

12. A component for electronic and electrical equipment, characterized in that, It is composed of the copper alloy as described in claim 1 or 2.

13. A component for a flexible device, characterized in that, It is composed of the copper alloy as described in claim 1 or 2.

14. A heat dissipation component, characterized in that, It is composed of the copper alloy as described in claim 1 or 2.

15. A metallic sealing material, characterized in that, It is composed of the copper alloy as described in claim 1 or 2.

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