Copper alloy, copper alloy plastic processing material, component for electronic / electrical apparatus, component for flexible device, component for heat dissipation, and metal sealing material

Abstract

Provided is a copper alloy having a composition containing 15 to 57 mass% of Zn, containing 12 mass% or less of Al, and having a Zn content of A mass% and an Al content of B mass% where A + 5 × B ≥ 30 and A + 3.5 × B ≤ 57 are satisfied, with the balance being Cu and unavoidable impurities. The copper alloy has a β-phase volume fraction of 50% or greater, the average value of Kernel average misorientation (KAM) values of the β phase is 2.0° or less, said average value having been obtained by measuring a measurement area of 1 mm2 or greater using an EBSD method at measurement intervals of 1-μm steps and excluding measurement points at which a CI value obtained by being analyzed using data analysis software OIM is 0.1 or less. The copper alloy has excellent conductivity, a low Young's modulus, and a sufficiently large elastic deformation amount, and is not likely to plastically deform even when subjected to significant deformation.

Description

Copper alloys, copper alloy plastic processing materials, electronic and electrical equipment parts, flexible device parts, heat dissipation parts, metal sealing materials

[0001] The present invention relates to a copper alloy suitable for electrical and electronic equipment components such as semiconductor components (e.g., home appliances and lead frames), printed wiring boards, heat sinks, switch components, bus bars, and connectors, as well as to a copper alloy plastically processed material made of this copper alloy, components for electronic and electrical equipment, components for flexible devices, heat dissipation components, and metal sealing materials. 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.

[0002] Conventionally, copper or copper alloys having excellent electrical and thermal conductivity have been used for electronic and electrical equipment components such as terminals, bus bars, lead frames, and heat dissipation members. For example, Cu-Zn alloys (so-called brass) have been used as copper alloys for the above-mentioned various applications, as shown in Patent Documents 1 to 3. In these Patent Documents 1 to 3, various elements other than Cu and Zn are added to ensure strength and workability.

[0003] Japanese Unexamined Patent Publication No. 2001-164328 (A) Japanese Unexamined Patent Application No. 2002-088428 (A) Japanese Unexamined Patent Application No. 2009-062610 (A) Japanese Unexamined Patent Application No. 2000-169920 (A)

[0004] In recent years, efforts have been made to make electronic and electric device components more flexible in order to improve the ease of use of electronic and electric devices. Therefore, materials constituting electronic and electric device components are required to have a low Young's modulus so that they can easily undergo elastic deformation, and a large amount of elastic deformation so that they can return to their original shape without undergoing plastic deformation even when subjected to large deformation. Here, conventional copper alloys such as those described in Patent Documents 1 to 3 do not have a low Young's modulus and cannot sufficiently increase the amount of elastic deformation, so there is a risk that they will easily undergo plastic deformation when subjected to large deformation.

[0005] Patent Document 4 reports a copper-based alloy that exhibits large pseudoelastic deformation due to its shape memory properties and superelastic properties while maintaining excellent workability. However, the Young's modulus is not sufficiently low, making it difficult to deform. Furthermore, the electrical conductivity is not disclosed, and when the electrical conductivity is low, there is a problem of large heat generation and large energy loss when electricity is applied.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a copper alloy that has excellent electrical conductivity, a low Young's modulus, a sufficiently large amount of elastic deformation, and is resistant to plastic deformation even when subjected to large deformation, as well as a copper alloy plastically processed material made from this copper alloy, a component for electronic and electrical equipment, a component for flexible devices, a heat dissipation component, and a metal sealing material.

[0007] To solve the above problems, the inventors conducted extensive research and obtained the following findings. It became clear that obtaining a copper material with a low Young's modulus requires both "obtaining a large amount of β phase" and "reducing strain within the material." The β phase that appears in copper alloys has a lower Young's modulus than the α phase used in conventional copper alloys, so obtaining a large amount of β phase can reduce the Young's modulus. Furthermore, by reducing the strain within the β phase, deformation within the β phase is not inhibited, making it possible to obtain an even lower Young's modulus. Furthermore, by uniformly distributing strain within the material, localized areas that are difficult to deform are eliminated, and the entire material deforms uniformly, resulting in a lower Young's modulus. From the above, it became clear that obtaining a large amount of β phase with small and uniformly dispersed strain is important for reducing the Young's modulus of a copper alloy.

[0008] The present invention has been made based on the above findings, and a copper alloy according to a first aspect of the present invention contains 15% by mass or more and 57% by mass or less of Zn, 12% by mass or less of Al, and has a composition that satisfies A+5×B≧30 and A+3.5×B≦57, where A is A% by mass of Zn and B is B% by mass of Al, with the balance being Cu and inevitable impurities, and has a volume fraction of β phase of 50% or more, and has a thickness of 1 mm or less measured by an EBSD method. ２The above measurement area is measured at measurement intervals of 1 μm, and the average value of the KAM (Kernel Average Misorientation) value of the β phase measured excluding measurement points where the CI value analyzed by data analysis software OIM is 0.1 or less is 2.0° or less.

[0009] According to the copper alloy of aspect 1 of the present invention, the copper alloy contains 15% by mass or more and 57% by mass or less of Zn and 12% by mass or less of Al, where the Zn content is A% by mass and the Al content is B% by mass, satisfying A + 5 × B ≥ 30 and A + 3.5 × B ≤ 57, with the remainder being Cu and inevitable impurities. This composition provides excellent strength and electrical conductivity, as well as good thermal conductivity. Furthermore, the β phase can be sufficiently formed. Furthermore, the volume fraction of the β phase is 50% or more, and the average KAM value of the β phase is 2.0° or less. This results in a large proportion of the β phase, and sufficiently low strain, resulting in a sufficiently low Young's modulus and easy elastic deformation. This results in a sufficiently large amount of elastic deformation, making the alloy less susceptible to plastic deformation even when subjected to large deformation, making it suitable for applications requiring flexibility.

[0010] A copper alloy according to a second aspect of the present invention is characterized in that, in the copper alloy according to the first aspect of the present invention, it further contains 0.005% by mass or more and 10% by mass or less of Ni. Since the copper alloy according to the second aspect of the present invention contains 0.005% by mass or more and 10% by mass or less of Ni, the strength can be further improved by solid solution strengthening due to Ni and the formation of precipitates containing Ni and Al.

[0011] A copper alloy according to a third aspect of the present invention is characterized in that, in the copper alloy according to the first or second aspect of the present invention, it further contains one or more C-group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, and Ag in a total amount of 0.0005% by mass or more and 2.5% by mass or less. Since the copper alloy according to the third aspect of the present invention contains one or more C-group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, and Ag in a total amount of 0.0005% by mass or more and 2.5% by mass or less, it is possible to suppress plastic deformation of the β phase and further increase the amount of elastic deformation while maintaining electrical conductivity.

[0012] A copper alloy according to a fourth aspect of the present invention is characterized in that, in the copper alloy according to any one of the first to third aspects of the present invention, it further contains one or more D-group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, and misch metal (MM) in a total amount of 0.0005% by mass to 2.5% by mass. Since the copper alloy according to the fourth aspect of the present invention contains one or more D-group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, and misch metal (MM) in a total amount of 0.0005% by mass to 2.5% by mass, it is possible to suppress plastic deformation of the β phase and further increase the amount of elastic deformation while maintaining electrical conductivity.

[0013] A copper alloy according to a fifth aspect of the present invention is characterized in that the standard deviation of the KAM value of the β phase is 0.75° or less in the copper alloy according to any one of the first to fourth aspects of the present invention. According to the copper alloy according to the fifth aspect of the present invention, since the standard deviation of the KAM value of the β phase is 0.75° or less, strain is not localized, deformation is not inhibited by strain, and the Young's modulus can be reliably reduced.

[0014] The copper alloy of Aspect 6 of the present invention is characterized in that, when an α phase is present in the copper alloy of any one of Aspects 1 to 5 of the present invention, the average KAM value of the α phase is 2.0° or less. According to the copper alloy of Aspect 6 of the present invention, an α phase may be present in addition to the β phase, but since the average KAM value of this α phase is 2.0° or less, strain is sufficiently small and the Young's modulus can be kept low.

[0015] A copper alloy according to a seventh aspect of the present invention is the copper alloy according to any one of the first to sixth aspects of the present invention, characterized in that the average value of the GOS (Grain Orientation Spread) value of the β phase is 2.0° or less. According to the copper alloy according to the seventh aspect of the present invention, the average value of the GOS value of the β phase is 2.0° or less, strain is not localized, and the Young's modulus can be further reduced.

[0016] The copper alloy of Aspect 8 of the present invention is characterized in that the Young's modulus is 100 GPa or less in the copper alloy of any one of Aspects 1 to 7 of the present invention. According to the copper alloy of Aspect 8 of the present invention, since the Young's modulus is 100 GPa or less, the Young's modulus is sufficiently low, elastic deformation is easy, and the copper alloy can be suitably used in applications where flexibility is required.

[0017] A copper alloy according to Aspect 9 of the present invention is characterized in that the copper alloy according to any one of Aspects 1 to 8 of the present invention has a maximum elastic strain of 0.4% or more. According to the copper alloy according to Aspect 9 of the present invention, the maximum elastic strain is set to 0.4% or more, and the copper alloy is resistant to plastic deformation even when subjected to large deformation.

[0018] A copper alloy according to a tenth aspect of the present invention is characterized in that the copper alloy according to any one of the first to ninth aspects of the present invention has an electrical conductivity of 10% IACS or more. Since the copper alloy according to the tenth aspect of the present invention has an electrical conductivity of 10% IACS or more, electrical conductivity is ensured and the copper alloy can be suitably used as a material for current-carrying members.

[0019] A plastically worked copper alloy material according to an eleventh aspect of the present invention is characterized in that it is made of the copper alloy according to any one of the first to tenth aspects of the present invention.

[0020] A part for an electronic / electrical device according to a twelfth aspect of the present invention is characterized in that it is made of the copper alloy according to any one of the first to tenth aspects of the present invention.

[0021] A flexible device component according to a thirteenth aspect of the present invention is characterized in that it is made of the copper alloy according to any one of the first to tenth aspects of the present invention.

[0022] A heat dissipation component according to a fourteenth aspect of the present invention is characterized in that it is made of the copper alloy according to any one of the first to tenth aspects of the present invention.

[0023] A metal sealing material according to a fifteenth aspect of the present invention is characterized in that it is made of the copper alloy according to any one of the first to tenth aspects of the present invention.

[0024] According to the present invention, it is possible to provide a copper alloy that has excellent electrical conductivity, a low Young's modulus, a sufficiently large amount of elastic deformation, and is resistant to plastic deformation even when subjected to large deformation, as well as a copper alloy plastically processed material made of this copper alloy, components for electronic and electrical equipment, components for flexible devices, heat dissipation components, and metal sealing materials.

[0025] 1 is a flow diagram of a method for producing a copper alloy according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of maximum elastic strain in an example.

[0026] A copper alloy according to one embodiment of the present invention will be described below. The copper alloy according to this embodiment is used as a material for various parts, such as parts for electronic and electrical equipment, parts for flexible devices, parts for heat dissipation, and metal sealing materials.

[0027] The copper alloy of this embodiment contains 15% by mass or more and 57% by mass or less of Zn and 12% by mass or less of Al, where the Zn content is A% by mass and the Al content is B% by mass, satisfying A + 5 × B ≥ 30 and A + 3.5 × B ≤ 57, with the balance being Cu and unavoidable impurities. The copper alloy of this embodiment may further contain 0.005% by mass or more and 10% by mass or less of Ni.

[0028] The copper alloy of this embodiment may further contain one or more C group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, and Ag in a total amount of 0.0005% by mass to 2.5% by mass, or one or more D group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, and misch metal (MM) in a total amount of 0.0005% by mass to 2.5% by mass.

[0029] In the copper alloy of this embodiment, the volume fraction of the β phase is set to 50% or more, and the EBSD method is used to measure the thickness of 1 mm ２ The above measurement areas are measured at measurement intervals of 1 μm, and the average value of the KAM (Kernel Average Misorientation) values ​​of the β phase measured excluding measurement points where the CI value analyzed by the data analysis software OIM is 0.1 or less is 2.0° or less.

[0030] In the copper alloy of this embodiment, the standard deviation of the KAM value of the β phase is preferably 0.75° or less. Furthermore, in the copper alloy of this embodiment, the average value of the GOS (Grain Orientation Spread) value of the β phase is preferably 2.0° or less. Furthermore, in the copper alloy of this embodiment, if an α phase is present, the average value of the KAM value of this α phase is preferably 2.0° or less. Furthermore, the standard deviation of the KAM value of the α phase is preferably 0.75° or less.

[0031] Here, in the copper alloy of this embodiment, it is preferable that the Young's modulus is 100 GPa or less, the maximum elastic strain is 0.4% or more, and the electrical conductivity is 10% IACS or more.

[0032] The reasons for specifying the component composition, crystalline structure, and various properties of the copper alloy of this embodiment as described above will be explained below.

[0033] (Zn) The copper alloy of this embodiment is composed primarily of Cu and Zn. If the Zn content is less than 15% by mass, the β phase may be insufficient, the volume fraction of the β phase may be less than 50%, and the Young's modulus may be high. If the Zn content exceeds 57% by mass, a very brittle γ phase may appear, significantly reducing workability. Therefore, in this embodiment, the Zn content is set within the range of 15% by mass to 57% by mass. This allows for excellent strength, electrical conductivity, and good thermal conductivity. The Zn content is preferably 18% by mass or more, and more preferably 20% by mass or more. The Zn content is preferably 56% by mass or less, and more preferably 55% by mass or less.

[0034] (Al) Adding an appropriate amount of Al to a Cu-Zn alloy can further improve strength. Here, to suppress the formation of brittle γ phase and ensure sufficient β phase, the Al content must be 12 mass% or less, and the Zn content must be A mass%, the Al content must be B mass%, and the following conditions must be satisfied: A + 5 × B ≥ 30, and A + 3.5 × B ≤ 57. If A + 5 × B is less than 30, sufficient β phase cannot be obtained, resulting in a high Young's modulus. If A + 3.5 × B exceeds 57, the proportion of brittle γ phase increases, making processing difficult. The Al content is more preferably 11 mass% or less, and even more preferably 10 mass% or less. The Al content is more preferably 0.005 mass% or more, and even more preferably 0.01 mass% or more. Furthermore, A + 5 × B is more preferably 31 or more, and even more preferably 32 or more. Furthermore, A+3.5×B is more preferably 56 or less, and even more preferably 55 or less.

[0035] (Ni) Adding an appropriate amount of Ni to a Cu-Zn alloy not only strengthens the solid solution, but also produces precipitates containing Ni and Al when added together with Al, making it possible to further improve strength. Here, in order to obtain the effect of Ni improving strength without significantly reducing electrical conductivity, it is preferable that the Ni content be in the range of 0.005% by mass or more and 10% by mass or less. The Ni content is more preferably 0.01% by mass or more, and even more preferably 0.1% by mass or more. Furthermore, the Ni content is more preferably 9% by mass or less, and even more preferably 8% by mass or less. Furthermore, when Ni is not intentionally added, the Ni content may be less than 0.005% by mass.

[0036] (C-group element: one or more selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, and Ag) In the copper alloy of this embodiment, by containing one or more C-group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, and Ag, plastic deformation of the β phase is suppressed and the amount of elastic deformation is further increased. On the other hand, if these C-group elements are contained in large amounts, electrical conductivity may be reduced. Therefore, in the copper alloy of this embodiment, it is preferable that the total content of one or more C-group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, and Ag is within the range of 0.0005% by mass to 2.5% by mass. Co, Fe, Sn, Mg, and Ag are elements suitable for strengthening the β phase, and their optimal composition is 0.0005% to 1% by mass in total. Mn, Si, and Be are elements effective not only for strengthening the β phase but also for obtaining a larger amount of the β phase, and their optimal composition is 0.0005% to 1% by mass in total. Sb, Cd, and As are elements suitable for strengthening the β phase, and their optimal composition is 0.0005% to 0.5% by mass in total. The total content of C-group elements is preferably 0.001% by mass or more, and more preferably 0.005% by mass or more. The total content of C-group elements is preferably 2.0% by mass or less, and more preferably 1.5% by mass or less. If C-group elements are not intentionally added, the total content of C-group elements may be less than 0.0005% by mass.

[0037] (D-group element: one or more selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, MM) In the copper alloy of this embodiment, by containing one or more D-group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, MM, precipitates and compounds are formed, thereby suppressing plastic deformation of the β phase and further increasing the amount of elastic deformation. On the other hand, if these D-group elements are contained in large amounts, electrical conductivity may be reduced. Therefore, in the copper alloy of this embodiment, it is preferable that the total content of one or more D-group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, MM is within the range of 0.0005% by mass to 2.5% by mass. Ti, V, Cr, Zr, and MM are elements suitable for strengthening the β phase by reacting with oxygen, sulfur, P, B, C, etc. in the material to form compounds, and their optimal composition is a total of 0.0005 to 0.8 mass%. Nb, Mo, and W are elements suitable for strengthening the β phase, and their optimal composition is a total of 0.0005 to 0.5 mass%. P and C are elements suitable for deoxidizing the material and forming compounds with other elements to strengthen the β phase, and their optimal composition is a total of 0.0005 to 1 mass%. B is an element suitable for suppressing embrittlement of the material and forming compounds with other elements to strengthen the β phase, and its optimal composition is 0.0005 to 1 mass%. The total content of D group elements is preferably 0.001 mass% or more, and more preferably 0.005 mass% or more. The total content of the D group elements is more preferably 2.0% by mass or less, and even more preferably 1.5% by mass or less. When the D group elements are not intentionally added, the total content of the D group elements may be less than 0.0005% by mass.

[0038] In addition, examples of inevitable impurities other than the above-mentioned elements 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 may be contained to the extent that they do not affect the characteristics. Since these inevitable impurities may reduce the conductivity, the total amount is preferably 2.5 mass% or less, more preferably 2.0 mass% or less, and even more preferably 1.5 mass% or less.

[0039] (Volume Fraction of β Phase) In Cu—Zn alloys, in addition to the β phase, there is a possibility that the α phase and the γ phase may appear. Here, since the Young's modulus decreases due to deformation of the β phase, if the volume fraction of the β phase is less than 50%, the β phase cannot be sufficiently deformed, resulting in a high Young's modulus. Therefore, in the copper alloy of this embodiment, the volume fraction of the β phase is set to 50% or more. The volume fraction of the β phase is preferably 60% or more, and more preferably 70% or more. Although not particularly limited, the volume fraction of the β phase may be 100% or less, 98% or less, or 95% or less.

[0040] (Average KAM Value of β Phase) The KAM (Kernel Average Misorientation) value measured by EBSD is a value calculated by averaging the misorientation between one pixel and the pixels surrounding it. Since the shape of a pixel is a regular hexagon, when the proximity order is set to 1, the average misorientation between six adjacent pixels is calculated as the KAM value. By using this KAM value, local misorientation, i.e., the distribution of strain, can be visualized. The smaller the amount of strain inside the material, the weaker the inhibition of deformation due to strain and the lower the Young's modulus. Therefore, the average 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. Although not particularly limited, the average KAM value of the β phase may be 0.01° or more, 0.10° or more, or 0.20° or more.

[0041] (Standard deviation of KAM value of β phase) When strain is localized, the standard deviation of the above-mentioned KAM value becomes large. In the region where strain is localized, deformation is inhibited by the strain, resulting in a high Young's modulus. 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. Although not particularly limited, the standard deviation of the KAM value of the β phase may be 0.01° or more, 0.03° or more, or 0.05° or more.

[0042] (Average GOS Value of β Phase) The GOS (Grain Orientation Spread) value measured by EBSD represents the average value of the difference between each pixel and the average angle difference θ of each pixel in the crystal, calculated for all pixels within the crystal grain. Here, the average value is calculated using the number of crystals, not the size of each crystal region. In other words, a large GOS value indicates that strain present in the crystal grain is localized. Therefore, if the GOS value is high, that is, if strain is present unevenly, localized areas that are difficult to deform will occur, resulting in a high Young's modulus. For this reason, 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. Note that the average value is calculated using the number of crystal grains. Although not particularly limited, the average value of the GOS value of the β phase may be 0.01° or more, 0.10° or more, or 0.15° or more.

[0043] (Average value and standard deviation of KAM value of α phase) In the copper alloy of this embodiment, an α phase may be present in addition to the β phase. When an α phase is present, it is preferable that the amount of strain is small even in this α phase. It is also preferable that strain is not localized in the α phase. 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. Although not particularly limited, the average value of the KAM value of the α phase may be 0.01° or more, 0.10° or more, or even 0.20° or more. 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. Although not particularly limited, the standard deviation of the KAM value of the α phase may be 0.01° or more, 0.03° or more, or 0.05° or more.

[0044] (Young's modulus) In the copper alloy of this embodiment, a low Young's modulus is required so that elastic deformation can be easily performed. Specifically, in the copper alloy of this embodiment, the Young's modulus is preferably 100 GPa or less. The Young's modulus is more preferably 90 GPa or less, and even more preferably 80 GPa or less. Although not particularly limited, the Young's modulus may be 10 GPa or more, 15 GPa or more, or 20 GPa or more.

[0045] (Maximum Elastic Strain) In the copper alloy of this embodiment, it is required to ensure an elastic deformation amount so that plastic deformation does not easily occur even when subjected to large deformation. Specifically, in the copper alloy of this embodiment, the maximum elastic strain is preferably 0.4% or more. The maximum elastic strain is more preferably 0.45% or more, and even more preferably 0.5% or more. Although not particularly limited, the maximum elastic strain may be 8% or less, 6.5% or less, or 5.5% or less.

[0046] (Electrical Conductivity) In the copper alloy of this embodiment, when the electrical conductivity is 10% IACS or more, it is particularly suitable as a material for current-carrying members that are parts for electric and electronic devices. The electrical conductivity of the copper alloy of this embodiment is preferably 12% IACS or more, and more preferably 14% IACS or more. Although not particularly limited, the electrical conductivity of the copper alloy of this embodiment may be 80% IACS or less, 70% IACS or less, or 60% IACS or less.

[0047] Next, an example of a method for producing the copper alloy according to this embodiment will be described with reference to the flow chart shown in FIG.

[0048] (Melting and Casting Step S01) First, the above-mentioned elements are added to the molten copper obtained by melting an oxygen-free copper raw material to adjust the composition, thereby producing a molten copper alloy. Note that, for adding various elements, single elements or master alloys, etc. can be used. Furthermore, raw materials containing the above-mentioned elements may be melted together with the copper raw material. Here, it is preferable that each element has a purity of 99.9 mass% or more, so-called 3N, or 99.99 mass% or more, so-called 4N. In the melting step, in order to reduce the hydrogen concentration, H ２ It is preferable to perform atmospheric melting in an inert gas atmosphere (e.g., Ar gas) with a low O vapor pressure, and to minimize the holding time during melting. The molten copper alloy with the adjusted composition is then poured into a mold to produce an ingot. Note that, when mass production is taken into consideration, it is preferable to use a continuous casting method or a semi-continuous casting method.

[0049] (Hot Working Step S02) The obtained ingot is subjected to hot working to introduce strain and to deform the shape to a predetermined size. By introducing strain during hot working, high strain can be applied to the coarse crystals, thereby improving the homogeneity of the material. In the hot working step S02, a certain processing rate is required to destroy the cast structure, and the total processing rate must be 50% or more, preferably 55% or more, and more preferably 60% or more. While the plastic processing method is not particularly limited, rolling is preferred when the final shape is a plate or strip. For wire or rod, extrusion or groove rolling is preferred, and forging or pressing is preferred for bulk shapes.

[0050] (Warm Working Step S03) Next, the resulting hot-worked material is subjected to warm working to introduce strain while causing phase transformation and to deform the shape to a predetermined size. In this warm working step S03, multiple passes are performed at a temperature range of 200°C to 600°C, where the α+β phase is stable and a sufficient diffusion rate can be obtained, with an average working rate per pass of 20% or less, to preferentially apply strain to the easily deformable β phase. Furthermore, the total working rate in the warm working step S03 must be 20% or more, preferably 25% or more, and more preferably 30% or more. While the plastic working method is not particularly limited, rolling is preferred when the final shape is a plate or strip. For wire or rod, extrusion or groove rolling is preferred, while forging or pressing is preferred for bulk shapes.

[0051] (First heat treatment step S04) Next, heat treatment is performed in the α+β phase temperature range to homogenize and / or solutionize the material, precipitate a fine α phase, and obtain a uniformly dispersed β phase while causing recrystallization. The heat treatment method is not particularly limited, but it is preferably performed in a non-oxidizing or reducing atmosphere. The heat treatment temperature must be 600°C or lower, preferably 550°C or lower. On the other hand, if the temperature is too low, diffusion becomes insufficient, so it must be 350°C or higher. The cooling method after heat treatment is performed using a method such as water quenching, which provides a cooling rate of 200°C / min or higher. The warm working step S03 and the first heat treatment step S04 may be repeated multiple times.

[0052] (Cold working step S05) After the first heat treatment step S04, cold working is performed. The working temperature is in the range of -200°C to 400°C. The total working rate is 30% or more, and a uniform strain distribution is obtained by applying a large strain. In this cold working step S05, there are no particular limitations on the working method, and for example, rolling, wire drawing, extrusion, groove rolling, forging, pressing, etc. can be used. In this embodiment, wire drawing is performed.

[0053] (Second heat treatment step S06) Next, the cold-worked material is heat-treated to form a large amount of β phase. For highly strained cold-worked material, high-temperature conditions, a slow heating rate, and a fast cooling rate can increase the proportion of β phase and freeze a structure with an average β phase KAM value of 2.0° or less. While the heat treatment method is not particularly limited, it is preferable to perform the heat treatment in a non-oxidizing or reducing atmosphere. Furthermore, the heat treatment temperature must be high. Since a sufficient amount of β phase cannot be obtained at a low temperature, 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 is too high, it will exceed the melting point of the material, so the heat treatment temperature must be 1000°C or less. Furthermore, the heating rate must be slow, at 10°C / min or less. By slowing the heating rate, a structure with a high β phase KAM value of 2.0 or less can be obtained. On the other hand, the cooling method must be a method such as water quenching, with a cooling rate of 200°C / min or more. If the cooling rate is slow, there is a possibility that many phases other than the β phase will appear during cooling, which could result in a decrease in the proportion of the β phase. Note that hot working may be performed after the heat treatment to improve the efficiency of rough processing and to homogenize the structure.

[0054] (Tempering Process Step S07) The copper material after the recrystallization heat treatment may be subjected to tempering process to adjust the material strength. If a low material strength is required, tempering process may not be performed. The final thickness and wire diameter are not particularly limited. In this tempering process step S07, there is no particular limitation on the processing method, and for example, rolling, wire drawing, extrusion, groove rolling, forging, pressing, etc. can be used.

[0055] The copper alloy (plastically worked copper alloy material) of this embodiment is manufactured by the steps described above. The means for adjusting the volume fraction of the β phase, the average value of the KAM value, and the like to fall within the above ranges is not limited to a specific method, but can be achieved, for example, by controlling the temperature in the warm working step S03, the temperature in the second heat treatment step S06, the heating rate, the cooling temperature, and the like, as described above.

[0056] The copper alloy of this embodiment, configured as described above, contains 15% by mass or more and 57% by mass or less of Zn and 12% by mass or less of Al, where the Zn content is A% by mass and the Al content is B% by mass, satisfying A + 5 × B ≥ 30 and A + 3.5 × B ≤ 57, with the remainder being Cu and inevitable impurities. This composition provides excellent strength and electrical conductivity, as well as good thermal conductivity. Furthermore, the volume fraction of the β phase is 50% or more, and the average KAM value of this β phase is 2.0° or less. This results in a large proportion of the β phase, and sufficiently low strain, resulting in a sufficiently low Young's modulus and easy elastic deformation. This provides a sufficiently wide range of elastic deformation, preventing easy plastic deformation even when subjected to large deformation, making the alloy suitable for applications requiring flexibility.

[0057] In this embodiment, when the alloy further contains 0.005 mass % to 10 mass % of Ni, the strength can be further improved.

[0058] In the present embodiment, when one or more C group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, and Ag are further contained in a range of 0.0005 mass % or more and 2.5 mass % or less in total, it is possible to suppress plastic deformation of the β phase and further increase the amount of elastic deformation while maintaining electrical conductivity.

[0059] In the present embodiment, when one or more D group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, and MM are further contained in a range of 0.0005 mass % or more and 2.5 mass % or less in total, it is possible to suppress plastic deformation of the β phase and further increase the amount of elastic deformation while maintaining electrical conductivity.

[0060] In this embodiment, when the standard deviation of the KAM value of the β phase is 0.75° or less, the strain is not localized, deformation is not hindered by the strain, and the Young's modulus can be reliably reduced. This further increases the amount of elastic deformation, and even when subjected to large deformation, the material does not easily undergo plastic deformation, making it suitable for use in applications requiring flexibility.

[0061] In this embodiment, when the α phase has an average KAM value of 2.0° or less, the α phase is present in addition to the β phase, but 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 kept low. This further increases the amount of elastic deformation, and even when subjected to large deformation, the material does not easily undergo plastic deformation, making it suitable for use in applications requiring flexibility.

[0062] In this embodiment, when the average value of the GOS (Grain Orientation Spread) value of the β phase is 2.0° or less, strain is not localized and the Young's modulus can be kept low. This further increases the amount of elastic deformation, and even when subjected to large deformation, the material does not easily undergo plastic deformation, making it suitable for use in applications requiring flexibility.

[0063] In this embodiment, when the maximum elastic strain is 0.4% or more, the amount of elastic deformation is sufficiently secured, and even if subjected to a large deformation, the material will not easily undergo plastic deformation, making it suitable for use in applications requiring flexibility.

[0064] In this embodiment, when the Young's modulus is 100 GPa or less, the Young's modulus is sufficiently low to facilitate elastic deformation, and the film can be suitably used in applications requiring flexibility, such as flexible devices and printed wiring used therein, as well as metal sealing materials.

[0065] In this embodiment, when the electrical conductivity is 10% IACS or more, the electrical conductivity is ensured, and the material can be suitably used as a material for electronic and electrical device components such as terminals, current-carrying members, probe needles, thermal interface materials, and heat dissipation components.

[0066] Although the copper alloy according to the embodiment of the present invention has been described above, the present invention is not limited thereto and can be appropriately modified within the scope of the technical concept of the invention. In the above embodiment, an example of a method for manufacturing a copper alloy has been described, but the method for manufacturing a copper alloy is not limited to that described in the above embodiment and may be manufactured by appropriately selecting an existing manufacturing method.

[0067] The results of confirmation experiments conducted to confirm the effects of the present invention will be described below.

[0068] First, raw materials consisting of pure copper with a purity of 99.999% by mass or higher and each additive element with a purity of 99.9% or higher were prepared. These were then placed in a high-purity graphite crucible and subjected to high-frequency melting in an atmospheric furnace with an Ar gas atmosphere. The resulting mixture was adjusted to the composition shown in Table 1, and poured into a mold made of insulating material (Isowool) to produce an ingot. The size of the ingot was approximately 100 mm in diameter and approximately 150 to 200 mm in length.

[0069] Next, the obtained ingot was subjected to hot working (hot extrusion) in an Ar gas atmosphere under the conditions shown in Table 2. After the thermal working, surface lathing was performed to remove the oxide film on the surface, and the ingot was processed to a predetermined size. Thereafter, the size was appropriately adjusted to obtain the final shape. Then, under the conditions shown in Table 2, warm working, primary heat treatment, cold working, secondary heat treatment, and thermal refining were performed to produce wire rods for property evaluation made of the copper alloys of the present invention examples and comparative examples, each having a final wire diameter of 1 mm to 5 mm.

[0070] The copper alloys of the present invention and comparative examples obtained as described above were evaluated as follows. The evaluation results are shown in Table 3.

[0071] (Composition Analysis) Measurement samples were taken from the obtained ingots and measured using a high frequency induction catalytic luminescence analyzer (ICP).

[0072] (Volume fraction of β phase) A sample of 10 mm in length was cut out from the wire for characteristic evaluation, and the cross section in the vertical direction of processing was mechanically polished using waterproof polishing paper and diamond abrasive grains, and then finished by polishing using colloidal silica solution. This sample was analyzed by an EBSD measuring device (Quanta FEG 450 manufactured by FEI, OIM Data Collection manufactured by EDAX / TSL (now AMETEK)) and analysis software (OIM Data Analysis ver. 8.6 manufactured by EDAX / TSL (now AMETEK)) at an electron beam acceleration voltage of 15 kV, a measurement interval of 1 μm, and a measurement interval of 1 mm. ２ In the above measurement areas, except for measurement points where the CI value was 0.1 or less, the misorientation of each crystal grain was analyzed to identify the crystalline phase. The proportion of the area identified as β phase in each measurement field was taken as the area fraction of β phase, and the average area fraction of three or more fields was taken as the volume fraction of β phase.

[0073] (KAM value, GOS value) In the same manner as described above for the volume fraction of the β phase, analysis was performed using an EBSD measurement device and analysis software to determine the KAM value of all pixels of the β phase, and the average value and standard deviation were calculated. The average value of the GOS value was also calculated. When the α phase was present, the KAM value of all pixels of the α phase was also determined, and the average value and standard deviation were calculated.

[0074] (Conductivity) A test piece with a length of 60 mm was taken from the wire for characteristic evaluation, and the electrical resistance was measured by a four-terminal method. The dimensions of the test piece were measured using a micrometer, and the volume of the test piece was calculated. The electrical conductivity was calculated from the measured electrical resistance value and volume. The test piece was taken so that its longitudinal direction was parallel to the processing direction of the wire for characteristic evaluation.

[0075] (Young's Modulus) Young's modulus E was determined from the gradient in the elastic region of the stress-elongation curve by attaching a contact type extensometer to the above test piece and conducting a mechanical test in accordance with JIS Z 2241. The strain rate was 5×10 ―４ s ―１ It was decided.

[0076] (Maximum Elastic Strain) In the same tensile test as above, as shown in Figure 2, stress was repeatedly applied and unloaded so that the applied strain increased by 0.5%, and the difference between the applied strain and the residual strain when the residual strain first occurred upon unloading was taken as the maximum elastic strain. Maximum Elastic Strain = Applied Strain - Residual Strain

[0077]

[0078]

[0079]

[0080] In Comparative Example 1, the composition was inappropriate, and the volume fraction of the β phase was 0%, resulting in a high Young's modulus of 110 GPa and a small maximum elastic strain of 0.1%. In Comparative Example 2, the composition was inappropriate, and the volume fraction of the β phase was 0%, resulting in a high Young's modulus of 115 GPa and a small maximum elastic strain of 0.1%. 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 high at 120 GPa, and the small maximum elastic strain was 0.2%. 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 small maximum elastic strain was 0.3%. 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 high at 105 GPa, and the maximum elastic strain was small at 0.3%. In Comparative Examples 6, 7, and 8, A + 3.5 × B exceeded 57, and wire rods for characteristic evaluation could not be produced due to poor workability.

[0081] In contrast, in Inventive Example 1-17, the volume fraction of the β phase was 50% or more, the average KAM value of the β phase was 2.0° or less, and the maximum elastic strain was large, at 0.4% or more. In addition, the electrical conductivity was 10% IACS or more, indicating excellent electrical conductivity.

[0082] As a result of the above confirmatory experiments, it was confirmed that the present invention can provide a copper alloy that has excellent electrical conductivity, a low Young's modulus, a sufficiently large amount of elastic deformation, and is resistant to plastic deformation even when subjected to large deformation.

[0083] According to the present invention, it is possible to provide a copper alloy that is excellent in electrical conductivity, has a low Young's modulus, a sufficiently large amount of elastic deformation, and is resistant to plastic deformation even when subjected to large deformation.

Claims

1. A composition containing 15% by mass or more and 57% by mass or less of Zn and 12% by mass or less of Al, where the Zn content is A% by mass and the Al content is B% by mass, A + 5 × B ≧ 30 and A + 3.5 × B ≦ 57, with the balance being Cu and unavoidable impurities; the volume fraction of the β phase is 50% or more; and the EBSD method is used to measure the thickness of 1 mm ２ The above measurement area is measured at measurement intervals of 1 μm, and the average value of the KAM (Kernel Average Misorientation) value of the β phase measured excluding measurement points where the CI value analyzed by data analysis software OIM is 0.1 or less is 2.0 ° or less. Copper alloy characterized by the above.

2. The copper alloy according to claim 1, further comprising 0.005% by mass or more and 10% by mass or less of Ni.

3. A copper alloy according to claim 1 or 2, further comprising one or more C group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As and Ag in a total amount of 0.0005% by mass or more and 2.5% by mass or less.

4. The copper alloy according to claim 1 or 2, further comprising one or more D group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C and misch metals in a total amount of 0.0005% by mass or more and 2.5% by mass or less.

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

6. A copper alloy according to claim 1 or 2, characterized in that when it has an α phase, the average KAM value of the α phase is 2.0° or less.

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

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

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

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

11. A plastically worked copper alloy material comprising the copper alloy according to claim 1 or 2.

12. A part for electronic or electrical equipment, comprising the copper alloy according to claim 1 or 2.

13. A part for a flexible device, comprising the copper alloy according to claim 1 or 2.

14. A heat dissipation part made of the copper alloy according to claim 1 or 2.

15. A metal sealing material comprising the copper alloy according to claim 1 or 2.

Images