WO2025105254A1 - Copper alloy, copper alloy plastic processing material, component for electronic/electrical apparatus, component for flexible device, component for heat dissipation, and metal sealing material - Google Patents

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 seal materials

The present invention relates to a copper alloy suitable for use in, for example, home appliances, semiconductor parts such as lead frames, printed wiring boards, heat sinks, switch parts, bus bars, connectors, and other electric and electronic equipment parts; and to a copper alloy plastically processed material made of this copper alloy, electronic and electric equipment parts, flexible device parts, heat dissipation parts, 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.

2. Description of the Related Art Conventionally, copper or copper alloys having excellent electrical conductivity and heat transfer properties have been used for electronic and electric device components such as terminals, bus bars, lead frames, and heat dissipation members.
As copper alloys for the above-mentioned various applications, for example, Cu-Zn based alloys (so-called brass) are used 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.

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

In recent years, efforts have been made to make electronic and electrical equipment parts more flexible in order to improve the ease of use of electronic and electrical equipment. Therefore, materials that constitute electronic and electrical equipment parts are required to have a low Young's modulus so that they can easily undergo elastic deformation, but also 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, in conventional copper alloys such as those described in Patent Documents 1 to 3, the Young's modulus is not low and the amount of elastic deformation cannot be made sufficiently large, so there is a risk that the alloys may easily undergo plastic deformation when subjected to large deformation.

Patent Document 4 reports a copper-based alloy that exhibits large pseudoelastic deformation due to its shape memory property and superelastic property while maintaining excellent workability. However, the Young's modulus is not sufficiently low, and deformation is not easy.
Furthermore, when the electrical conductivity is not disclosed and the electrical conductivity is low, there is a problem that heat is generated significantly when electricity is passed through the material, resulting in a large energy loss.

This invention was 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 of this copper alloy, electronic and electrical equipment parts, flexible device parts, heat dissipation parts, and metal sealing materials.

In order to solve the above problems, the present inventors conducted extensive research and obtained the following findings: It became clear that in order to obtain a copper material with a low Young's modulus, it is important to "obtain a large amount of β phase" and "reduce strain inside the material."
The β phase that appears in copper alloys has a lower Young's modulus than the α phase used in normal copper alloys, so by obtaining a large amount of β phase, the Young's modulus can be reduced. Furthermore, by reducing the internal strain of the β phase, deformation inside the β phase is not inhibited, making it possible to obtain an even lower Young's modulus.
Furthermore, by making the strain distribution within the material uniform, there are no locally difficult to deform areas, 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 strain and uniform dispersion is important for reducing the Young's modulus of a copper alloy.

The present invention has been made based on the above-mentioned findings, and the copper alloy of aspect 1 of the present invention contains 15 mass% or more and 57 mass% or less of Zn and 12 mass% or less of Al, where the Zn content is A mass% and the Al content is B mass%, satisfying A + 5 × B ≧ 30 and A + 3.5 × B ≦ 57, with the balance being Cu and inevitable impurities. The volume fraction of the β phase is 50% or more, and the average value of the KAM (Kernel Average Misorientation) value of the β phase measured by the EBSD method over a measurement area of 1 mm2 or more at measurement intervals of 1 ^μm , excluding measurement points where the CI value analyzed by the data analysis software OIM is 0.1 or less, is 2.0 ° or less.

According to the copper alloy of the first aspect 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, and satisfies A+5×B≧30 and A+3.5×B≦57, with the balance being Cu and inevitable impurities, so that the copper alloy has excellent strength and electrical conductivity and good thermal conductivity. Also, the β phase can be sufficiently formed.
Since 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, the proportion of the β phase is large and the strain is sufficiently small, so that the Young's modulus is sufficiently low and elastic deformation is easy. As a result, the amount of elastic deformation is sufficiently large, and even if a large deformation is received, plastic deformation is not easily caused, so that the material can be suitably used in applications where flexibility is required.

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

The copper alloy of embodiment 3 of the present invention is characterized in that, in the copper alloy of embodiment 1 or embodiment 2 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 range of 0.0005 mass% or more and 2.5 mass% or less in total.
According to the copper alloy of the third aspect of the present invention, the copper alloy 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. Therefore, the electrical conductivity can be maintained while suppressing the plastic deformation of the β phase and further increasing the elastic deformation amount.

The copper alloy of aspect 4 of the present invention is characterized in that, in the copper alloy of any one of aspects 1 to 3 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 in the range of 0.0005 mass% or more and 2.5 mass% or less.
According to the copper alloy of the fourth aspect 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 misch metal (MM) in a total amount of 0.0005% by mass or more and 2.5% by mass or less. This makes it possible to suppress plastic deformation of the β phase and further increase the amount of elastic deformation while maintaining electrical conductivity.

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

A copper alloy according to a sixth aspect of the present invention is characterized in that, in the copper alloy according to any one of the first to fifth aspects of the present invention, when the alloy has an α phase, the average KAM value of the α phase is 2.0° or less.
According to the copper alloy of the sixth aspect of the present invention, there may be an α phase in addition to the β phase. However, since the average value of the KAM value of this α phase is set to 2.0° or less, the distortion is sufficiently small, and the Young's modulus can be kept low.

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 of the seventh aspect of the present invention, the average value of the GOS value of the β phase is set to 2.0° or less, the strain is not localized, and the Young's modulus can be further suppressed to a low value.

The copper alloy of embodiment 8 of the present invention is characterized in that in any one of the copper alloys of embodiments 1 to 7 of the present invention, the Young's modulus is 100 GPa or less.
According to the copper alloy of aspect 8 of the present invention, since the Young's modulus is set to 100 GPa or less, the Young's modulus is sufficiently low, elastic deformation is facilitated, and the copper alloy can be suitably used in applications requiring flexibility.

A copper alloy according to a ninth aspect of the present invention is the copper alloy according to any one of the first to eighth aspects of the present invention, characterized in that the maximum elastic strain is 0.4% or more.
According to the copper alloy of the ninth aspect of the present invention, the maximum elastic strain is set to be 0.4% or more, and therefore, even when subjected to a large deformation, it is difficult to undergo plastic deformation.

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

The copper alloy plastic processing material of aspect 11 of the present invention is characterized in that it is made of any one of the copper alloys of aspects 1 to 10 of the present invention.

The electronic/electrical device part of aspect 12 of the present invention is characterized in that it is made of any one of the copper alloys of aspects 1 to 10 of the present invention.

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

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

The metal sealing material of aspect 15 of the present invention is characterized in that it is made of any one of the copper alloys of aspects 1 to 10 of the present invention.

The present invention provides 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, 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.

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

Below, a copper alloy according to one embodiment of the present invention will be described. 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 seal materials.

The copper alloy of this embodiment contains 15 mass % or more and 57 mass % or less of Zn and 12 mass % or less of Al, where the Zn content is A mass % and the Al content is B mass %, and the composition satisfies A + 5 × B ≧ 30 and A + 3.5 × B ≦ 57, with the balance being Cu and unavoidable impurities.
Moreover, the copper alloy of this embodiment may further contain 0.005 mass % to 10 mass % of Ni.

In addition, 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 range of 0.0005% by mass or more and 2.5% by mass or less in total.
In addition, the copper alloy of this embodiment may further contain 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 mass% or more and 2.5 mass% or less.

In the copper alloy of the present embodiment, the volume fraction of the β phase is set to 50% or more, and the average value of the KAM (Kernel Average Misorientation) values of the β phase measured by the EBSD method over a measurement area of 1 ^mm2 or more at measurement intervals of 1 μm, excluding measurement points where the CI value analyzed by the data analysis software OIM is 0.1 or less, is set to 2.0° or less.

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, it is preferable that the average value of the GOS (grain orientation spread) value of the β phase is 2.0° or less.
In the copper alloy of the present embodiment, when the copper alloy has an α phase, the average KAM value of the α phase is preferably 2.0° or less. Also, the standard deviation of the KAM value of the α phase is preferably 0.75° or less.

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

The reasons for specifying the component composition, crystal structure, and various properties of the copper alloy of this embodiment as described above are explained below.

(Zn)
The copper alloy of this embodiment is mainly composed of Cu and Zn. If the Zn content is less than 15 mass%, the β phase is not present sufficiently, the volume fraction of the β phase is less than 50%, and the Young's modulus may be high. If the Zn content is more than 57 mass%, a very brittle γ phase appears, and the workability is greatly reduced.
Therefore, in this embodiment, the Zn content is set to the range of 15 mass % to 57 mass %, inclusive, which allows the alloy to have excellent strength and electrical conductivity as well as good thermal conductivity.
Here, the Zn content is preferably 18 mass% or more, more preferably 20 mass% or more, and is preferably 56 mass% or less, more preferably 55 mass% or less.

(Al)
By adding an appropriate amount of Al to the Cu--Zn alloy, it is possible to further improve the strength.
Here, in order to suppress the brittle γ phase and ensure that the β phase is sufficiently present, the Al content is set to 12 mass% or less, and the Zn content is set to A mass%, the Al content is set to B mass%, and A+5×B≧30 and A+3.5×B≦57 are satisfied. If A+5×B is less than 30, sufficient β phase cannot be obtained and the Young's modulus becomes high. If A+3.5×B exceeds 57, the proportion of the brittle γ phase increases, making processing difficult.
The Al content is more preferably 11% by mass or less, and even more preferably 10% by mass or less. The Al content is more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more.
Furthermore, A+5×B is more preferably 31 or greater, and even more preferably 32 or greater.
Furthermore, A+3.5×B is more preferably 56 or less, and even more preferably 55 or less.

(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 improving strength due to Ni without significantly decreasing electrical conductivity, the Ni content is preferably set within the range of 0.005 mass % or more and 10 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. The Ni content is more preferably 9% by mass or less, and even more preferably 8% by mass or less.
When Ni is not intentionally added, the Ni content may be less than 0.005 mass %.

(C group elements: one or more selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, and Ag)
In the copper alloy of the present embodiment, by containing 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 amount of elastic deformation is further increased. On the other hand, if the copper alloy contains a large amount of these C group elements, the electrical conductivity may decrease.
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 within the range of 0.0005 mass% or more and 2.5 mass% or less in total.
Co, Fe, Sn, Mg, and Ag are elements suitable for strengthening the β phase, and their optimum composition is a total of 0.0005 to 1 mass%. Mn, Si, and Be are elements effective for strengthening the β phase as well as obtaining a larger amount of the β phase, and their optimum composition is a total of 0.0005 to 1 mass%. Sb, Cd, and As are elements suitable for strengthening the β phase, and their optimum composition is a total of 0.0005 to 0.5 mass%.
The total content of the C group elements is more preferably 0.001% by mass or more, and even more preferably 0.005% by mass or more, and is more preferably 2.0% by mass or less, and even more preferably 1.5% by mass or less.
When no C group elements are intentionally added, the total content of C group elements may be less than 0.0005 mass %.

(D group element: one or more selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, and MM)
In the copper alloy of the present embodiment, by containing one or more D group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, and 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 the copper alloy contains a large amount of these D group elements, the electrical conductivity may decrease.
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 within the range of 0.0005 mass% or more and 2.5 mass% or less in total.
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 a compound, and their optimal composition is 0.0005 mass% to 0.8 mass% in total. Nb, Mo, and W are elements suitable for strengthening the β phase, and their optimal composition is 0.0005 mass% to 0.5 mass% in total. P and C are elements suitable for deoxidizing the material and forming a compound with other elements to strengthen the β phase, and their optimal composition is 0.0005 mass% to 1 mass% in total. B is an element suitable for suppressing the embrittlement of the material and forming a compound with other elements to strengthen the β phase, and its optimal composition is 0.0005 mass% to 1 mass% in total.
The total content of the D group elements is more preferably 0.001% by mass or more, and even more preferably 0.005% by mass or more, and 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 mass %.

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, Li, etc. These impurity elements may be contained to the extent that they do not affect the characteristics.
Since these unavoidable impurities may reduce electrical 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.

(Volume fraction of β phase)
In Cu-Zn alloys, in addition to the β phase, the α phase and the γ phase may appear. Since the Young's modulus decreases as the β phase deforms, when the volume fraction of the β phase is less than 50%, the β phase cannot deform sufficiently, 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.

(Average value of 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 degree of proximity is set to 1, the average misorientation between six adjacent pixels is calculated as the KAM value. By using this KAM value, the local misorientation, that is, 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.
For this reason, 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.
Although not particularly limited, the average value of the KAM value of the β phase may be 0.01° or more, 0.10° or more, or 0.20° or more.

(Standard deviation of KAM value of β phase)
When strain is localized, the standard deviation of the KAM value described above increases. In the region where strain is localized, deformation is hindered by the strain, resulting in a high Young's modulus.
For this reason, 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.

(Average value of GOS value of β phase)
The GOS (Grain Orientation Spread) value measured by EBSD is the average value of the difference between each pixel and the average value θ of the angle difference of each pixel in the crystal, calculated for all pixels in the crystal grain. Here, the average value is calculated using the number of each crystal, not the size of the region of each crystal. In other words, a large GOS value indicates that the strain present in the crystal grain is localized. Therefore, if the GOS value is high, that is, if the strain is present non-uniformly, there will be parts that are difficult to deform locally, resulting in a high Young's modulus.
Therefore, the average value of the 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.

(Average value and standard deviation of α-phase KAM value)
In the copper alloy of this embodiment, an α phase may exist in addition to a β phase. When an α phase exists, it is preferable that the amount of strain is small in the α phase. It is also preferable that the strain is not localized in the α phase.
For this reason, 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 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.

(Young's Modulus)
The copper alloy of this embodiment is required to have a low Young's modulus so as to facilitate elastic deformation.
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.

(Maximum elastic strain)
In the copper alloy of this embodiment, it is required to ensure an amount of elastic deformation so that it does not easily undergo plastic deformation even when subjected to a 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.

(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 electrically conductive 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.

Next, an example of a method for producing the copper alloy of this embodiment will be described with reference to the flow diagram shown in Figure 1.

(Melting and casting process S01)
First, the above-mentioned elements are added to the molten copper obtained by melting the oxygen-free copper raw material to adjust the composition, and a molten copper alloy is produced. In addition, a single element or a mother alloy can be used to add various elements. In addition, a raw material containing the above-mentioned elements may be melted together with the copper raw material. Here, each element is preferably so-called 3N, which has a purity of 99.9 mass% or more, or so-called 4N, which has a purity of 99.99 mass% or more. In the melting process, in order to reduce the hydrogen concentration, it is preferable to perform atmospheric melting in an inert gas atmosphere (e.g., Ar gas) with a low vapor pressure of H ₂ O, and to minimize the holding time during melting. Then, the molten copper alloy with the adjusted composition is poured into a mold to produce an ingot. In addition, when considering mass production, it is preferable to use a continuous casting method or a semi-continuous casting method.

(Hot working step S02)
The resulting ingot is then hot worked to introduce strain and to change its shape to a desired size. By introducing strain during hot working, it is possible to impart high strain to the material while the crystals are still coarse, which makes it possible to increase the homogeneity of the material.
In the hot working step S02, a certain processing rate is necessary because it is necessary to destroy the cast structure, and the total processing rate needs to be 50% or more, preferably 55% or more, and more preferably 60% or more.
The plastic processing method is not particularly limited, but it is preferable to adopt rolling when the final shape is a plate or strip, extrusion or groove rolling when the final shape is a wire or rod, and forging or pressing when the final shape is a bulk shape.

(Warm processing step S03)
Next, the hot-worked material is subjected to warm working in order to introduce strain while causing a phase transformation and to change the shape to a predetermined size.
In this warm working step S03, multiple passes of working are performed in a temperature range of 200°C or higher and 600°C or lower, in which the α+β phase is stable and a sufficient diffusion rate can be obtained, with the average working rate per pass being 20% or less, so that strain is preferentially applied to the β phase, which is easily deformed.
Moreover, 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.
The plastic processing method is not particularly limited, but it is preferable to adopt rolling when the final shape is a plate or strip, extrusion or groove rolling when the final shape is a wire or rod, and forging or pressing when the final shape is a bulk shape.

(First heat treatment step S04)
Next, the alloy is subjected to a heat treatment in the temperature range of the α+β phase in order to homogenize and/or solutionize the alloy and cause recrystallization while precipitating fine α phase and obtaining a uniformly dispersed β phase.
Here, the heat treatment method is not particularly limited, but it is preferable to carry out the heat treatment in a non-oxidizing or reducing atmosphere.
The heat treatment temperature must be 600° C. or less, and is preferably 550° C. or less. On the other hand, if the temperature is too low, diffusion becomes insufficient, so the heat treatment temperature must be 350° C. or more.
The cooling method after the heat treatment is carried out by a method such as water quenching at a cooling rate of 200° C./min or more.
The warm working step S03 and the first heat treatment step S04 may be repeated multiple times.

(Cold working step S05)
After the first heat treatment step S04, cold working is performed. The working temperature is within 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 addition, in this cold working step S05, the processing method is not particularly limited, and for example, rolling, wire drawing, extrusion, groove rolling, forging, pressing, etc. can be adopted. In this embodiment, wire drawing is performed.

(Second heat treatment step S06)
Next, in order to form a large amount of β phase, the cold-worked material is subjected to heat treatment. By subjecting the cold-worked material to a large strain, to high temperature conditions, slowing the heating rate, and speeding up the cooling rate, it is possible to increase the proportion of β phase and freeze a structure in which the average KAM value of the β phase is 2.0° or less.
Here, the heat treatment method is not particularly limited, but it is preferable to carry out the heat treatment in a non-oxidizing or reducing atmosphere.
In addition, the heat treatment temperature must be high. If the temperature is low, a sufficient amount of β phase cannot be obtained, so the heat treatment temperature is preferably 600° C. or higher, and 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 lower.
Furthermore, the heating rate needs to be slow, at 10° C./min or less. By slowing down the heating rate, a structure with a high average KAM value of the β phase of 2.0 or less can be obtained.
On the other hand, the cooling method needs to be a method with a cooling rate of 200° C./min or more, such as water quenching. If the cooling rate is slow, there is a possibility that many phases other than the β phase will appear during cooling, and the proportion of the β phase may decrease.
In order to improve the efficiency of rough processing and to make the structure uniform, hot working may be carried out after the heat treatment.

(Refining process S07)
The copper material that has been subjected to the recrystallization heat treatment may be subjected to a tempering process in order to adjust the material strength. If a lower material strength is required, tempering process may not be performed. There are no particular restrictions on the final thickness and wire diameter.
In addition, in this thermal refining step S07, the processing method is not particularly limited, and for example, rolling, wire drawing, extrusion, groove rolling, forging, pressing, etc. can be adopted.

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

The copper alloy of this embodiment having the above-described configuration contains 15 mass % or more and 57 mass % or less of Zn and 12 mass % or less of Al, where the Zn content is A mass %, the Al content is B mass %, and the composition satisfies A + 5 × B ≧ 30 and A + 3.5 × B ≦ 57, with the balance being Cu and unavoidable impurities. Therefore, the copper alloy has excellent strength and electrical conductivity as well as good thermal conductivity.
Since 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, the proportion of the β phase is large and the strain is sufficiently small, so that the Young's modulus is sufficiently low and elastic deformation is easy. As a result, the amount of elastic deformation is sufficiently wide, and even if a large deformation is applied, plastic deformation does not easily occur, and the material can be suitably used in applications where flexibility is required.

In this embodiment, if the material further contains 0.005% by mass or more and 10% by mass or less of Ni, the strength can be further improved.

In this embodiment, when the alloy 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 ranging from 0.0005% by mass to 2.5% by mass, the electrical conductivity can be maintained while suppressing the plastic deformation of the β phase and further increasing the amount of elastic deformation.

In this embodiment, if the alloy further contains one or more D group elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, and MM in a total amount ranging from 0.0005% by mass to 2.5% by mass, the electrical conductivity can be maintained while suppressing plastic deformation of the β phase and further increasing the amount of elastic deformation.

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 a large deformation, the material does not easily undergo plastic deformation, making it suitable for use in applications where flexibility is required.

In this embodiment, when the material has an α phase and the average KAM value of this α phase is 2.0° or less, the material has an α phase in addition to the β phase. However, since the average KAM value of this α phase is set to 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 a large deformation, the material does not easily undergo plastic deformation, making it suitable for use in applications where flexibility is required.

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

In this embodiment, when the maximum elastic strain is 0.4% or more, the amount of elastic deformation is sufficiently ensured, and even if a large deformation occurs, the material does not easily undergo plastic deformation, making it suitable for use in applications where flexibility is required.

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 material can be suitably used in applications requiring flexibility, such as flexible devices and the printed wiring used therein, as well as metal sealing materials.

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, conductive members, probe needles, thermal interface materials, and heat dissipation components.

The above describes the copper alloy as an embodiment of the present invention, but the present invention is not limited to this, and can be modified as appropriate without departing from the technical concept of the invention. In the above embodiment, an example of a method for manufacturing a copper alloy is described, but the method for manufacturing a copper alloy is not limited to that described in the above embodiment, and the copper alloy may be manufactured by appropriately selecting an existing manufacturing method.

Below, we explain the results of the confirmation experiments conducted to confirm the effectiveness of the present invention.

First, a raw material consisting of pure copper with a purity of 99.999% by mass or more and each additive element with a purity of 99.9% or more was prepared, and then placed in a high-purity graphite crucible and melted by high-frequency induction in an atmospheric furnace with an Ar gas atmosphere. The composition of the components was adjusted as shown in Table 1, and the molten metal was 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 150 to 200 mm in length.

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 processing, the surface was turned on a lathe to remove the oxide film on the surface, and the piece was machined to a specified size. After that, 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 carried out to produce wire rods for characteristic evaluation made of the copper alloys of the present invention and comparative examples and having final wire diameters of 1 mm to 5 mm.

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.

(composition analysis)
Measurement samples were taken from the resulting ingot and were measured using a high-frequency induction catalytic emission spectrometer (ICP).

(Volume fraction of β phase)
A sample having a length of 10 mm was cut out from the wire for characteristic evaluation, and the cross section perpendicular to the processing direction was mechanically polished using waterproof abrasive paper and diamond abrasive grains, and then finish-polished using a colloidal silica solution. This sample was analyzed for the orientation difference of each crystal grain using an EBSD measurement 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, measurement intervals of 1 μm, and a measurement area of 1 ^mm2 or more, excluding measurement points where the CI value was 0.1 or less, to identify the crystal phase. The proportion of the area identified as β phase in each measurement field was defined as the area fraction of β phase, and the average area fraction of three or more fields was defined as the volume fraction of β phase.

(KAM value, GOS value)
In the same manner as described above for the volume fraction of the β phase, the EBSD measurement device and analysis software were used to analyze the sample, and the KAM values of all pixels of the β phase were calculated, 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 values of all pixels of the α phase were also determined, and the average value and standard deviation were calculated.

(conductivity)
A test piece having 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.

(Young's Modulus)
The 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-mentioned test piece and carrying out a mechanical test in accordance with JIS Z 2241. The strain rate was 5×10 ⁻⁴ s ⁻¹ .

(Maximum elastic strain)
In the same tensile test as described above, as shown in FIG. 2, stress was repeatedly applied and unloaded so that the applied strain increased by 0.5% at a time, and the difference between the applied strain and the residual strain when the first residual strain occurred upon unloading was defined as the maximum elastic strain.
Maximum elastic strain = applied strain - residual strain

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 low 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 low 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 maximum elastic strain was small at 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 maximum elastic strain was small at 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.

In contrast, in Example 1-17 of the present invention, 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, and the electrical conductivity was excellent.

The results of the above confirmation experiments 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.

The present invention makes it 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.

Claims (15)

The alloy has a composition containing 15 mass % or more and 57 mass % or less of Zn and 12 mass % or less of Al, where the Zn content is A mass % and the Al content is B 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,
A copper alloy characterized in that an average value of KAM (Kernel Average Misorientation) value of the β phase measured by an EBSD method over a measurement area of 1 ^mm2 or more at a measurement interval of 1 μm, excluding measurement points where the CI value analyzed by data analysis software OIM is 0.1 or less, is 2.0 ° or less. The copper alloy according to claim 1, further comprising 0.005% by mass to 10% by mass of Ni. The 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 ranging from 0.0005% to 2.5% by mass. 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 range of 0.0005% by mass to 2.5% by mass in total. 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. The 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. 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. The copper alloy according to claim 1 or 2, characterized in that the Young's modulus is 100 GPa or less. The copper alloy according to claim 1 or 2, characterized in that the maximum elastic strain is 0.4% or more. The copper alloy according to claim 1 or 2, characterized in that the electrical conductivity is 10% IACS or more. A copper alloy plastic processing material comprising the copper alloy described in claim 1 or claim 2. A component for electronic or electrical equipment, characterized by being made of the copper alloy described in claim 1 or claim 2. A flexible device component made of the copper alloy described in claim 1 or claim 2. A heat dissipation component made of the copper alloy described in claim 1 or claim 2. A metal sealing material comprising the copper alloy described in claim 1 or claim 2.

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