Copper alloy, copper alloy plastic processing material, component for electronic / electrical machine, component for flexible device, component for heat radiation, metal seal material

Abstract

To provide a copper alloy excellent in conductivity while having a sufficiently large elastic deformation amount with a low Young's modulus and unlikely to cause a plastic deformation even under a large deformation.SOLUTION: A copper alloy has a composition including 15-57 mass% Zn, 12 mass% or less Al, satisfying A+5×B≥30 and A+3.5×B≤57 in which the Zn content is A mass% and the Al content is B mass%, and a balance Cu with inevitable impurities. A volume fraction in a β phase is 50% or more. When a measurement area of 8 mm2 or more is measured at a measurement interval 8 μm step by an EBSD method and analyzed excluding a measurement point with a CI value of 0.1 or less obtained through an analysis by data analysis software OIM, and an interval between measurement points in which an orientation difference between neighboring measurement points is 5° or more is regarded as a crystal grain boundary, a ratio of each coincidence boundary length of 3≤Σ≤29 to all crystal grain boundary lengths L at which measured β phases are abutting with each other is 4% or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a copper alloy suitable for parts for electric and electronic devices such as home appliances, semiconductor parts such as lead frames, printed wiring boards, heat sinks, switch parts, bus bars, connectors, etc., a copper alloy plastic working material made of this copper alloy, parts for electronic and electric devices, parts for flexible devices, parts for heat dissipation, and metal sealing materials.

Background Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, in order to improve the usability of electronic and electrical devices, parts for electronic and electrical devices have been made flexible. Therefore, in the materials constituting parts for electronic and electrical devices, it is required that the Young's modulus is low so that elastic deformation can be easily performed, and even when a large deformation is received, plastic deformation does not occur and the material returns to its original shape, and the amount of elastic deformation is large. Here, in conventional copper alloys as described in Patent Documents 1-3, the Young's modulus does not become low, the amount of elastic deformation cannot be made sufficiently large, and there is a risk of easily undergoing plastic deformation when receiving a large deformation. In Patent Document 4, a copper-based alloy that exhibits a large pseudo-elastic deformation due to shape memory characteristics and super-elastic characteristics while maintaining excellent workability has been reported. However, the Young's modulus is not sufficiently low and deformation is not easy. In addition, the conductivity is not disclosed, and when the conductivity is low, there is a problem that heat generation is large and energy loss is large when energized.

[0005] This invention has been made in view of the above-described circumstances, and provides a copper alloy having excellent conductivity, a low Young's modulus, a sufficiently large amount of elastic deformation, and being less likely to undergo plastic deformation even when receiving a large deformation, a copper alloy plastic working material made of this copper alloy, parts for electronic and electrical devices, parts for flexible devices, parts for heat dissipation, and a metal sealing material.

Means for Solving the Problems

[0006] As a result of intensive studies by the inventors to solve the above problems, the following findings were obtained. In order to obtain a copper material with a low Young's modulus, it has become clear that it is important to "obtain many β phases" and "reduce the grain boundary energy of the β phase" by weight. Since the β phase that appears in copper alloys has a lower Young's modulus than the α phase used in ordinary copper alloys, the Young's modulus can be reduced by obtaining many β phases. Furthermore, in a random grain boundary with a large grain boundary energy, deformation inhibits each other. However, the presence of many grain boundaries with a small grain boundary energy facilitates deformation and a low Young's modulus can be obtained. Therefore, it has been found that it is important to have a β-phase structure containing many corresponding grain boundaries and grain boundaries with a small misorientation in order to lower the Young's modulus of the copper alloy.

[0007] The present invention has been made based on the above findings. The copper alloy of Aspect 1 of the present invention contains 15% by mass or more and 57% by mass or less of Zn, contains 12% by mass or less of Al, the content of Zn is A% by mass, the content of Al is B% by mass, and A + 5×B ≥ 30 and A + 3.5×B ≤ 57 are satisfied, and the balance is composed of Cu and inevitable impurities. The volume fraction of the β-phase is 50% or more, and the measurement area of 8 mm or more is measured at a measurement interval of 8 μm steps by the EBSD method, and the analysis is performed excluding the measurement points where the CI value analyzed by the data analysis software OIM is 0.1 or less. The grain boundaries are defined as the grain boundaries between the measurement points where the misorientation between adjacent measurement points is 5° or more, and the ratio of each corresponding grain boundary length of 3 ≤ Σ ≤ 29 to the total grain boundary length where the measured β-phases are in contact with each other is 4% or more. 2 According to the copper alloy of Aspect 1 of the present invention, it contains 15% by mass or more and 57% by mass or less of Zn, contains 12% by mass or less of Al, the content of Zn is A% by mass, the content of Al is B% by mass, and A + 5×B ≥ 30 and A + 3.5×B ≤ 57 are satisfied, and the balance is composed of Cu and inevitable impurities. Therefore, it is excellent in strength and conductivity and can have good thermal conductivity. In addition, the β-phase can be sufficiently formed.

[0008] And since the volume fraction of the β-phase is 50% or more, the proportion occupied by the β-phase is large and the Young's modulus becomes sufficiently low. ​Then, in the β phase, the points where the azimuth difference between adjacent measurement points is 5° or more are defined as grain boundaries. Since the ratio of each corresponding grain boundary length with 3 ≦ Σ ≦ 29 to the total grain boundary length where the measured β phases are in contact is 4% or more, the grain boundary energy of the β phase can be reduced, the Young's modulus can be made sufficiently low, and the amount of elastic deformation can be increased. Therefore, even when subjected to large deformation, it does not easily undergo plastic deformation and can be suitably used for applications where flexibility is required.

[0009] The copper alloy of Embodiment 2 of the present invention is characterized in that, in the copper alloy of Embodiment 1 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 Embodiment 2 of the present invention, since it contains 0.005% by mass or more and 10% by mass or less of Ni, solid solution strengthening by Ni and further improvement in strength can be achieved by the formation of precipitates containing Ni and Al.

[0010] 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, Ag in a total amount in the range of 0.0005% by mass or more and 2.5% by mass or less. According to the copper alloy of Embodiment 3 of the present invention, since it contains one or more C-group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag in a total amount in the range of 0.0005% by mass or more and 2.5% by mass or less, while maintaining the conductivity, plastic deformation of the β phase can be suppressed and the amount of elastic deformation can be further increased.

[0011] The copper alloy of Embodiment 4 of the present invention is characterized in that, in any one of the copper alloys of Embodiments 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, mischmetal (MM) in a total amount in the range of 0.0005% by mass or more and 2.5% by mass or less. According to the copper alloy of Aspect 4 of the present invention, since it contains one or more Group D elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, mischmetal (MM) in a total range of 0.0005% by mass or more and 2.5% by mass or less, while maintaining the conductivity, plastic deformation of the β phase can be suppressed and the elastic deformation amount can be further increased.

[0012] The copper alloy of Aspect 5 of the present invention is characterized in that, in any one of the copper alloys of Aspect 1 to Aspect 4 of the present invention, the ratio of grain boundaries with an orientation difference of 20° or less at the grain boundaries where β phases are in contact is 10% or more. According to the copper alloy of Aspect 5 of the present invention, since the ratio of grain boundaries with an orientation difference of 20° or less is 10% or more, it is possible to suppress the adjacent crystal grains from inhibiting each other's deformation during deformation, and by being more easily deformed, the Young's modulus can be lowered.

[0013] The copper alloy of Aspect 6 of the present invention is characterized in that, in any one of the copper alloys of Aspect 1 to Aspect 5 of the present invention, the maximum value of the crystal orientation intensity plot in the processing direction of the β phase obtained from the texture analysis by the EBSD method is 2 or more. According to the copper alloy of Aspect 6 of the present invention, since the maximum value of the crystal orientation intensity plot in the processing direction of the β phase is 2 or more, it is possible to suppress the adjacent crystal grains from inhibiting each other's deformation during deformation, and by being more easily deformed, the Young's modulus can be lowered.

[0014] The copper alloy of Aspect 7 of the present invention is characterized in that, in any one of the copper alloys of Aspect 1 to Aspect 6 of the present invention, the maximum value of the crystal orientation intensity plot of the β phase exists within 30° of orientation difference from <001> or <101>. According to the copper alloy of Aspect 7 of the present invention, the maximum value of the crystal orientation intensity plot of the β phase is within 30° of orientation difference from <001> or <101>, and the crystal orientation of the β phase is aggregated to <001> or <101>, so the Young's modulus can be made lower.

[0015] The copper alloy of Aspect 8 of the present invention is characterized in that, among the copper alloys of any one of Aspects 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 100 GPa or less, the Young's modulus is sufficiently low, elastic deformation is facilitated, and it can be suitably used for applications where flexibility is required.

[0016] The copper alloy of Aspect 9 of the present invention is characterized in that, among the copper alloys of any one of Aspects 1 to 8 of the present invention, the maximum elastic strain is 0.4% or more. According to the copper alloy of Aspect 9 of the present invention, since the maximum elastic strain is 0.4% or more, it is difficult to undergo plastic deformation even when subjected to large deformation.

[0017] The copper alloy of Aspect 10 of the present invention is characterized in that, among the copper alloys of any one of Aspects 1 to 9 of the present invention, the conductivity is 10% IACS or more. According to the copper alloy of Aspect 10 of the present invention, since the conductivity is 10% IACS or more, conductivity is ensured, and it can be suitably used as a material for current-carrying members.

[0018] The copper alloy wrought product of Aspect 11 of the present invention is characterized by being made of any one of the copper alloys of Aspects 1 to 10 of the present invention.

[0019] The component for electronic and electrical equipment of Aspect 12 of the present invention is characterized by being made of any one of the copper alloys of Aspects 1 to 10 of the present invention.

[0020] The component for a flexible device of Aspect 13 of the present invention is characterized by being made of any one of the copper alloys of Aspects 1 to 10 of the present invention.

[0021] The component for heat dissipation of Aspect 14 of the present invention is characterized by being made of any one of the copper alloys of Aspects 1 to 10 of the present invention.

[0022] The metal sealing material of Embodiment 15 of the present invention is characterized by being made of any one of the copper alloys of Embodiments 1 to 10 of the present invention.

Effects of the Invention

[0023] According to the present invention, there can be provided a copper alloy having excellent conductivity, a low Young's modulus, a sufficiently large elastic deformation amount, and being less likely to undergo plastic deformation even when subjected to large deformation, a copper alloy plastic working material made of this copper alloy, parts for electronic and electrical equipment, parts for flexible devices, parts for heat dissipation, and a metal sealing material.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0025] Hereinafter, a copper alloy which is an embodiment of the present invention will be described. The copper alloy of this embodiment is used, for example, 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. The copper alloy of this embodiment contains 15% by mass or more and 57% by mass or less of Zn, contains 12% by mass or less of Al, sets the content of Zn as A% by mass and the content of Al as B% by mass, and satisfies A + 5×B ≧ 30 and A + 3.5×B ≦ 57, with the balance being Cu and inevitable impurities. Further, in the copper alloy of this embodiment, it may further contain 0.005% by mass or more and 10% by mass or less of Ni.

[0026] Further, in the copper alloy of this embodiment, it may further contain one or more C group elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag in a total range of 0.0005% by mass or more and 2.5% by mass or less. Further, in the copper alloy of the present embodiment, one or more Group D elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, misch metal (MM) may be contained in a total amount of 0.0005 mass% or more and 2.5 mass% or less.

[0027] And, in the copper alloy of the present embodiment, the volume fraction of the β phase is 50% or more, and the CI value analyzed by data analysis software OIM after measuring a measurement area of 8 mm or more at a measurement interval of 8 μm step by the EBSD method is excluded from the measurement points where the CI value is 0.1 or less, and the grain boundary between the measurement points where the azimuth difference between adjacent measurement points in the β phase is 5° or more is defined as the grain boundary, and the ratio of each corresponding grain boundary length of 3 ≦ Σ ≦ 29 to the total grain boundary length where the measured β phases are in contact is 4% or more. 2 And, in the copper alloy of the present embodiment, the volume fraction of the β phase is 50% or more, and the CI value analyzed by data analysis software OIM after measuring a measurement area of 8 mm or more at a measurement interval of 8 μm step by the EBSD method is excluded from the measurement points where the CI value is 0.1 or less, and the grain boundary between the measurement points where the azimuth difference between adjacent measurement points in the β phase is 5° or more is defined as the grain boundary, and the ratio of each corresponding grain boundary length of 3 ≦ Σ ≦ 29 to the total grain boundary length where the measured β phases are in contact is 4% or more.

[0028] Also, in the copper alloy of the present embodiment, it is preferable that the ratio of the grain boundaries with an azimuth difference of 20° or less at the grain boundaries where the β phases are in contact is 10% or more. Furthermore, in the copper alloy of the present embodiment, it is preferable that the maximum value of the intensity plot of the crystal orientation of the β phase in the processing direction obtained from the texture analysis by the EBSD method is 2 or more. Also, in the copper alloy of the present embodiment, it is preferable that the maximum value of the intensity plot of the crystal orientation of the β phase exists within 30° of the azimuth difference from <001> or <101>.

[0029] Here, in the copper alloy of the present embodiment, it is preferable that the Young's modulus is 100 GPa or less. Also, in the copper alloy of the present embodiment, it is preferable that the maximum elastic strain is 0.4% or more. Furthermore, in the copper alloy of the present embodiment, it is preferable that the conductivity is 10% IACS or more.

[0030] In the copper alloy of the present embodiment, the reasons for defining the component composition, crystal structure, and various properties as described above will be explained below.

[0031] (Zn) The copper alloy of this embodiment contains Cu and Zn as the main components. Here, when the Zn content is less than 15% by mass, the β-phase does not sufficiently exist, the volume fraction of the β-phase is less than 50%, and there is a risk that the Young's modulus will increase. Also, when it exceeds 57% by mass, a very brittle γ-phase appears and the workability greatly deteriorates. Therefore, in this embodiment, the Zn content is set within the range of 15% by mass or more and 57% by mass or less. Thereby, it can be excellent in strength and conductivity and can have good thermal conductivity. Here, the Zn content is preferably 18% by mass or more, and more preferably 20% by mass or more. Also, the Zn content is preferably 56% by mass or less, and more preferably 55% by mass or less.

[0032] (Al) By adding an appropriate amount of Al to the Cu-Zn alloy, it becomes possible to further improve the strength. Here, in order to sufficiently present the β-phase while improving the strength, the Al content is set to 12% by mass or less, the Zn content is set to A% by mass, the Al content is set to B% by mass, and it is preferable to satisfy A + 5×B ≥ 30 and A + 3.5×B ≤ 57. When A + 5×B is less than 30, a sufficient β-phase cannot be obtained and the Young's modulus increases. When A + 3.5×B exceeds 57, the proportion of the brittle γ-phase increases and processing becomes difficult. The Al content is more preferably 11% by mass or less, and even more preferably 10% by mass or less. Also, 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.

[0033] (Ni) By adding an appropriate amount of Ni to the Cu-Zn alloy, in addition to solid solution strengthening, precipitates containing Ni and Al are formed by adding it together with Al, making it possible to further improve the strength. Here, in order to obtain the effect of strength improvement by Ni without significantly reducing the conductivity, it is preferable that the content of Ni is in the range of 0.005% by mass or more and 10% by mass or less. In addition, the content of Ni is more preferably 0.01% by mass or more, and even more preferably 0.1% by mass or more. Also, the content of Ni is more preferably 9% by mass or less, and even more preferably 8% by mass or less. Also, when Ni is not intentionally added, the content of Ni may be less than 0.005% by mass.

[0034] (Group C elements: one or more selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag) In the copper alloy of this embodiment, by containing one or more Group C elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag, the plastic deformation of the β phase is suppressed and the elastic deformation amount becomes even larger. On the other hand, if a large amount of these Group C elements is contained, there is a risk of a decrease in conductivity. Therefore, in the copper alloy of this embodiment, it is preferable that the total content of one or more Group C elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag is in the range of 0.0005% by mass or more and 2.5% by mass or less. Co, Fe, Sn, Mg, Ag are elements suitable for strengthening the β phase, and their optimal composition is 0.0005% by mass to 1% by mass in total. Mn, Si, Be are effective elements for obtaining more β phase in addition to strengthening the β phase, and their optimal composition is 0.0005% by mass to 1% by mass in total. Sb, Cd, As are elements suitable for strengthening the β phase, and their optimal composition is 0.0005% by mass to 0.5% by mass in total. In addition, the total content of Group C elements is more preferably 0.001% by mass or more, and even more preferably 0.005% by mass or more. Further, the total content of Group C elements is more preferably 2.0% by mass or less, and even more preferably 1.5% by mass or less. Also, when Group C elements are not intentionally added, the total content of Group C elements may be less than 0.0005% by mass.

[0035] (Group D elements: one or more selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, mischmetal) In the copper alloy of the present embodiment, by containing one or more Group D elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, and mischmetal (MM), precipitates and compounds are formed, suppressing the plastic deformation of the β phase and further increasing the elastic deformation amount. On the other hand, if a large amount of these Group D elements is contained, there is a risk of a decrease in conductivity. Therefore, in the copper alloy of the present embodiment, it is preferable that the total content of one or more Group D elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, and mischmetal (MM) is in the range of 0.0005% by mass or more and 2.5% by mass or less. 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 0.0005% by mass to 0.8% by mass in total. Nb, Mo, and W are elements suitable for strengthening the β phase, and their optimal composition is 0.0005% by mass to 0.5% by mass in total. 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 0.0005% by mass to 1% by mass in total. B is an element suitable for suppressing the embrittlement of the material and forming compounds with other elements to strengthen the β phase, and its optimal composition is 0.0005% by mass to 1% by mass. In addition, the total content of Group D elements is more preferably 0.001% by mass or more, and even more preferably 0.005% by mass or more. Further, the total content of Group D elements is more preferably 2.0% by mass or less, and even more preferably 1.5% by mass or less. Also, when Group D elements are not intentionally added, the total content of Group D elements may be less than 0.0005% by mass.

[0036] Incidentally, examples of inevitable impurities other than the above-described 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 within a range that does not affect the properties. Since these inevitable impurities may reduce the conductivity, the total amount is preferably 1% by mass or less, more preferably 0.7% by mass or less, and even more preferably 0.5% by mass or less.

[0037] (Volume fraction of β-phase) In a Cu-Zn alloy, in addition to the β-phase, an α-phase and a γ-phase may appear. Here, since the Young's modulus decreases when the β-phase is deformed, when the volume fraction of the β-phase is less than 50%, the β-phase cannot be deformed sufficiently and the Young's modulus becomes high. Therefore, in the copper alloy of the present embodiment, the volume fraction of the β-phase is set to 50% or more. In addition, the volume fraction of the β-phase is preferably 60% or more, and more preferably 70% or more.

[0038] (Ratio of corresponding grain boundary length where 3 ≦ Σ ≦ 29) When the corresponding grain boundaries with 3≦Σ≦29 have low grain boundary energy, if the ratio of the length of the corresponding grain boundaries with 3≦Σ≦29 (Σ3,5,7,9,11,13a,13b,15,17a,17b,19a,19b,21a,21b,23,25a,25b,27a,27b,29a,29b) to the total grain boundary length where the measured β-phases are in contact is 4% or more, the deformation inhibition between adjacent grains is reduced, and the deformation becomes easier, resulting in a decrease in Young's modulus. Therefore, in this embodiment, the ratio of the length of the corresponding grain boundaries with 3≦Σ≦29 to the total grain boundary length where the measured β-phases are in contact is set to 4% or more. Note that the ratio of the length of the corresponding grain boundaries with 3≦Σ≦29 to the total grain boundary length where the measured β-phases are adjacent is preferably 5% or more. More preferably, it is 6% or more.

[0039] (Ratio of grain boundary length with misorientation angle of 20° or less) When the ratio of the grain boundary length with a misorientation angle of 20° or less at the grain boundaries where the β-phases are in contact is 10% or more, it is possible to suppress the adjacent grains from inhibiting each other's deformation during deformation, and by making the deformation easier, the Young's modulus can be made lower. Therefore, the ratio of the grain boundary length with a misorientation angle of 20° or less is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more.

[0040] (Maximum value of intensity plot of crystal orientation of β-phase) The intensity plot of the crystal orientation of the β-phase is a plot of the orientation distribution of the observed sample on an inverse pole figure, and its intensity represents how many times the intensity of each orientation is compared to the state where all orientations appear with the same probability (set to 1). By setting the maximum value of the intensity plot of the crystal orientation of the β-phase to 2 or more, it is possible to suppress the adjacent grains from inhibiting each other's deformation during deformation, and by making the deformation easier, the Young's modulus can be made lower. Therefore, in the present embodiment, the maximum value of the intensity plot of the crystal orientation of the β-phase in the working direction obtained from the texture analysis by the EBSD method is preferably 2 or more, more preferably 2.5 or more. Even more preferably, it is 3 or more.

[0041] (Orientation of the maximum value of the intensity plot of the crystal orientation of the β-phase) By aggregating the crystal orientation of the β-phase to <001> or <101>, the Young's modulus can be made lower. If it deviates greatly from <001> or <101>, the Young's modulus will increase. Therefore, it is preferable that the maximum value of the intensity plot of the crystal orientation of the β-phase exists within 30° from <001> or <101>, more preferably within 25°. Even more preferably, it is within 20°.

[0042] (Young's modulus) In the copper alloy of the present embodiment, a low Young's modulus is required so that it can be easily elastically deformed. Specifically, in the copper alloy of the present embodiment, the Young's modulus is preferably 100 GPa or less. In addition, the Young's modulus is more preferably 90 GPa or less, and even more preferably 80 GPa or less.

[0043] (Maximum elastic strain) In the copper alloy of the present embodiment, it is required to ensure the elastic deformation amount so that it does not plastically deform easily even when subjected to large deformation. Specifically, in the copper alloy of the present embodiment, the maximum elastic strain is preferably 0.4% or more. In addition, the maximum elastic strain is more preferably 0.45% or more, and even more preferably 0.5% or more.

[0044] (Conductivity) In the copper alloy of the present embodiment, when the conductivity is 10% IACS or more, it is particularly suitable as a material for the current-carrying member which is a component for electric and electronic equipment. Note that the conductivity of the copper alloy according to this embodiment is preferably 12% IACS or more, and more preferably 14% IACS or more.

[0045] Next, an example of a method for manufacturing the copper alloy according to this embodiment will be described with reference to the flowchart shown in FIG. 1.

[0046] (Melting and casting process S01) First, the above-described elements are added to the molten copper obtained by melting the oxygen-free copper raw material to adjust the components, thereby producing a molten copper alloy. Note that for the addition of various elements, elemental substances, master alloys, etc. can be used. Further, a raw material containing the above-described elements may be melted together with the copper raw material. Here, each element is preferably so-called 3N with a purity of 99.9 mass% or more, or so-called 4N with a purity of 99.99 mass% or more. In the melting process, for the reduction of the hydrogen concentration, atmosphere melting is performed in an inert gas atmosphere (for example, Ar gas) with a low vapor pressure of H 2 2O, and it is preferable to minimize the holding time during melting. Then, the molten copper alloy with adjusted components is poured into a mold to produce an ingot. Note that in consideration of mass production, it is preferable to use a continuous casting method or a semi-continuous casting method.

[0047] (Hot working process S02) Hot working is performed on the obtained ingot in order to homogenize the structure and deform the shape into a predetermined size. In hot working, by introducing strain, high strain can be applied to the state where the crystals are coarse, so that the homogeneity of the material can be improved. In the hot working process S02, since it is necessary to break the casting structure, a certain processing rate is required, and the total processing rate needs to be 50% or more, preferably 55% or more, and more preferably 60% or more. Note that the plastic working method is not particularly limited, but when the final shape is a plate or strip, it is preferable to adopt rolling. When it is a wire or rod, it is preferable to adopt extrusion, groove rolling, and when it is a bulk shape, it is preferable to adopt forging or pressing.

[0048] (Low processing step S03) Next, low processing with a total processing rate of 40% or less is performed. Here, the processing method is not particularly limited. However, when the final form is a plate or strip, rolling is adopted. Otherwise, forging, pressing, or groove rolling may be adopted. The temperature is not particularly limited, but it is preferably within the range of -200°C to 400°C, which can be either cold or warm. Here, by setting the processing rate to 40% or less, a large amount of strain is introduced into the easily processed crystal grains, and the strain distribution becomes non-uniform. Due to this strain non-uniformity, it is possible to suppress all crystal grains from growing simultaneously and grow crystal grains with similar crystal orientations, resulting in a structure with a high frequency of existence in a specific crystal orientation.

[0049] (Heat treatment step S04) Heat treatment is performed to achieve homogenization and obtain a large amount of β-phase. Here, the heat treatment method is not particularly limited, but it is preferably performed in a non-oxidizing or reducing atmosphere. Here, it is necessary to perform the heat treatment at a high temperature. When the temperature is low, a sufficient amount of β-phase cannot be obtained. Therefore, the heat treatment temperature is preferably 600°C or higher, more preferably 700°C or higher. Also, if the temperature becomes too high, it will exceed the melting point of the material, so the heat treatment temperature needs to 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, it is possible to suppress all crystal grains from growing simultaneously and grow crystal grains with similar crystal orientations, resulting in a structure with a high frequency of existence in a specific crystal orientation. The cooling method requires a method with a cooling rate of 200°C / min or higher, such as water quenching. When the cooling rate is slow, there is a possibility that phases other than the β-phase will appear during cooling, and the β-phase fraction will decrease. Also, for the purpose of improving the efficiency of rough processing and homogenizing the structure, hot processing may be performed after the heat treatment. The processing method is not particularly limited. However, when the final form is a plate or strip, rolling is adopted, and for wires or bars, extrusion or groove rolling is adopted. The combination of low processing and heat treatment is repeated three or more times to obtain many corresponding grain boundaries.

[0050] (Quenching and tempering process S05) Quenching and tempering may be performed on the recrystallized heat-treated copper material to adjust the material strength. If low material strength is required, quenching and tempering may not be necessary. The final thickness and wire diameter are not particularly limited. In this quenching and tempering process S05, the processing method is not particularly limited, and for example, rolling, wire drawing, extrusion, groove rolling, forging, pressing, etc. can be adopted.

[0051] Through the above processes, the copper alloy (copper alloy plastic processed material) of this embodiment is manufactured. The means for adjusting the volume fraction of the β-phase and the ratio of each corresponding grain boundary length of 3≤Σ≤29 within the above range is not limited to a specific method. For example, it is possible by controlling the total processing rate of low processing, the heating rate, the cooling rate of heat treatment, the number of repetitions of low rolling and heat treatment, etc. as described above.

[0052] According to the copper alloy of this embodiment configured as described above, it contains 15% by mass or more and 57% by mass or less of Zn, contains 12% by mass or less of Al, the content of Zn is A% by mass, the content of Al is B% by mass, and satisfies A + 5×B≥30 and A + 3.5×B≤57, with the balance being Cu and inevitable impurities. Therefore, it has excellent strength and conductivity and can have good thermal conductivity. And, the measurement points with an azimuth difference of 5° or more between adjacent measurement points in the β-phase are defined as grain boundaries, and the ratio of each corresponding grain boundary length of 3≤Σ≤29 to the total grain boundary length where the measured β-phases are in contact is 4% or more. Therefore, the grain boundary energy of the β-phase can be reduced, the Young's modulus can be made sufficiently low, and the elastic deformation amount can be increased. Therefore, even when subjected to large deformation, it does not easily become plastically deformed and can be suitably used for applications where flexibility is required.

[0053] In this embodiment, when further containing 0.005% by mass or more and 10% by mass or less of Ni, in addition to solid solution strengthening, precipitates containing Ni and Al are formed, so that the strength can be further improved.

[0054] In this embodiment, when further containing a total of 0.0005% by mass or more and 2.5% by mass or less of one or more Group C elements selected from Co, Fe, Mn, Si, Sn, Mg, Be, Sb, Cd, As, Ag, while maintaining the conductivity, the plastic deformation of the β phase can be suppressed and the elastic deformation amount can be further increased.

[0055] In this embodiment, when further containing a total of 0.0005% by mass or more and 2.5% by mass or less of one or more Group D elements selected from Ti, V, Cr, Nb, Mo, W, P, Zr, B, C, mischmetal (MM), while maintaining the conductivity, the plastic deformation of the β phase can be suppressed and the elastic deformation amount can be further increased.

[0056] In this embodiment, when the ratio of grain boundaries with an orientation difference of 20° or less at the grain boundaries where β phases are in contact is 10% or more, it is possible to suppress the adjacent crystal grains from inhibiting each other's deformation during deformation, and by making it easier to deform, the Young's modulus can be further lowered.

[0057] In this embodiment, when the maximum value of the intensity plot of the crystal orientation of the β phase in the processing direction obtained from the texture analysis by the EBSD method is 2 or more, it is possible to suppress the adjacent crystal grains from inhibiting each other's deformation during deformation, and by making it easier to deform, the Young's modulus can be further lowered.

[0058] In this embodiment, when the maximum value of the intensity plot of the crystal orientation of the β phase exists within 30° of the azimuth difference from <001> or <101>, since the crystal orientation of the β phase is aggregated to <001> or <101>, the Young's modulus can be made lower.

[0059] In this embodiment, when the Young's modulus is 100 GPa or less, the Young's modulus is sufficiently low and it can be easily elastically deformed, and it can be suitably used for applications that require flexibility, such as flexible devices, printed wirings used therein, and further metal sealing materials.

[0060] In this embodiment, when the maximum elastic strain is 0.4% or more, the elastic deformation amount is sufficiently ensured, and even when it is subjected to large deformation, it does not easily undergo plastic deformation, and it can be suitably used for applications that require flexibility.

[0061] In this embodiment, when the conductivity is 10% IACS or more, the conductivity is ensured, and it can be suitably used as a material for parts for electronic and electrical equipment, such as terminals, current-carrying members, probe needles, thermal interface materials, and heat radiating parts.

[0062] The copper alloy which is an embodiment of the present invention has been described above. However, the present invention is not limited thereto, and it can be appropriately changed without departing from the technical idea of the invention. In the above embodiment, an example of the manufacturing method of the copper alloy has been described. However, the manufacturing method of the copper alloy is not limited to that described in the above embodiment, and an existing manufacturing method may be appropriately selected for manufacturing.

Examples

[0063] The results of the confirmation experiments conducted to confirm the effects of the present invention will be described below.

[0064] First, raw materials made of pure copper with a purity of 99.999 mass% or more and each additive element of 99.9% or more were prepared, loaded into a high-purity graphite crucible, and high-frequency melted in an atmosphere furnace with an Ar gas atmosphere. It was adjusted to the component composition shown in Table 1 and poured into a heat insulating material (isowool) mold to produce an ingot. The size of the ingot was about 20 mm in thickness × about 100 mm in width × about 150 to 200 mm in length.

[0065] Next, the obtained ingot was hot-worked (hot-rolled) under the conditions shown in Table 2 in an Ar gas atmosphere. After hot working, surface grinding was performed to remove the oxide film on the surface, and cutting was carried out to a predetermined size. Then, the size was adjusted as appropriate to obtain the final shape. Then, under the conditions shown in Table 2, cold working, heat treatment, and tempering were carried out to produce strip-shaped materials for property evaluation made of the copper alloys of the inventive examples and comparative examples with a plate thickness of 1 mm to 5 mm.

[0066] The copper alloys of the inventive examples and comparative examples obtained as described above were evaluated as follows. The evaluation results are shown in Table 3.

[0067] (Composition analysis) Measurement samples were taken from the obtained ingots and measured using a high-frequency inductively coupled plasma optical emission spectrometer (ICP). The measurement was performed at two locations, the central part of the sample and the end part in the width direction, and the content with the higher content was taken as the content of the sample.

[0068] (Volume fraction of β phase) Samples of 10 mm × 20 mm were cut out from the strip-shaped materials for property evaluation. After mechanical polishing of the cross-section in the direction perpendicular to the processing using waterproof abrasive paper and diamond abrasive grains, finish polishing was performed using a colloidal silica solution. This sample was measured with 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 acceleration voltage of the electron beam of 15 kV and a measurement interval of 1 μm step over a measurement area of 1 mm 2 or more. Excluding the measurement points with a CI value of 0.1 or less, the analysis of the orientation difference of each crystal grain was performed, the crystal phase was identified, and the ratio of the area identified as the β phase in each measurement field of view was taken as the area ratio of the β phase. Measurements were performed in 3 or more fields of view, and the average value of the area ratios was taken as the volume fraction of the β phase.

[0069] (Ratio of corresponding grain boundary length) A 10 mm × 20 mm sample was cut out from the strip for property evaluation. After mechanical polishing of the cross-section in the direction perpendicular to the machining using waterproof abrasive paper and diamond abrasive grains, finish polishing was performed using a colloidal silica solution. This sample was measured with an EBSD measuring device (Quanta FEG 450 manufactured by FEI, OIM Data Collection manufactured by EDAX / TSL (currently AMETEK)) and analysis software (OIM Data Analysis ver. 8.6 manufactured by EDAX / TSL (currently AMETEK)) at an acceleration voltage of 15 kV of the electron beam and a measurement interval of 8 μm step over a measurement area of 8 mm 2 or more. Excluding the measurement points where the CI value was 0.1 or less, the misorientation of each grain was analyzed. The measurement points where the misorientation between adjacent measurement points was 5° or more were regarded as grain boundaries, and the correspondence relationship between adjacent grains was measured. Measurements were made in 3 or more fields of view, and the average value was taken as the ratio of the corresponding grain boundaries.

[0070] (Ratio of grain boundary length with misorientation of 20° or less) Similar to the ratio of the corresponding grain boundaries, measurement and analysis were performed by SEM-EBSD and OIM (registered trademark). The measurement points where the misorientation between adjacent measurement points was 5° or more were regarded as grain boundaries, and the misorientation between adjacent grains was measured. Measurements were made in 3 or more fields of view, the ratio of the grain boundary length with misorientation of 20° or less was determined for each field of view, and the average value was taken as the ratio of the grain boundaries with misorientation of 20° or less.

[0071] (Intensity plot of crystal orientation of β phase) at an acceleration voltage of 15 kV of the electron beam and a measurement interval of 8 μm step over a measurement area of 8 mm 2 or more. The direction perpendicular to the machining was measured, and excluding the measurement points where the CI value was 0.1 or less, the misorientation of each grain of the β phase was analyzed. The crystal orientation in the machining direction of each measurement point was plotted on an inverse pole figure, and an intensity plot was created. Measurements were made in 3 or more fields of view, and the maximum value was taken as the value of the intensity plot.

[0072] (Conductivity) Test pieces with a width of 10 mm and a length of 60 mm were taken from the strips for property evaluation, and the electrical resistance was determined by the four-terminal method. Also, the dimensions of the test pieces were measured using a micrometer, and the volume of the test pieces was calculated. Then, the conductivity was calculated from the measured electrical resistance value and volume. The test pieces were taken such that their longitudinal direction was parallel to the processing direction of the strips for property evaluation.

[0073] (Young's modulus) The Young's modulus E was determined from the slope in the elastic region of the stress-strain curve by attaching a contact extensometer to a test piece with the same shape as described above and performing a mechanical test in accordance with JIS Z 2241. The strain rate was 5×10 ―4 s ―1 The test pieces were taken and tested such that the tensile direction of the tensile test was parallel and perpendicular to the processing direction of the strips for property evaluation, and the lower value was shown in the table.

[0074] (Maximum elastic strain) In the tensile test similar to the above, as shown in Fig. 2, the application and removal of stress were repeated so that the applied strain increased by 0.5% each time, and the difference between the applied strain and the residual strain when residual strain first occurred was defined as the maximum elastic strain. For the maximum elastic strain, the test pieces were taken and tested such that they were parallel and perpendicular to the processing direction, and the larger value was shown in the table. Maximum elastic strain = Applied strain - Residual strain

[0075]

Table 1

[0076]

Table 2

[0077]

Table 3

[0078] In Comparative Example 1, the volume fraction of the β-phase was 100%, but the ratio of the corresponding grain boundary length was as low as 3.8%, the Young's modulus was as high as 112 GPa, and the maximum elastic strain was as small as 0.3%. In Comparative Example 2, the composition was not appropriate and the volume fraction of the β-phase was 0%. The Young's modulus was as high as 110 GPa, and the maximum elastic strain was as small as 0.1%. In Comparative Example 3, the volume fraction of the β-phase was 100%, but the ratio of the corresponding grain boundary length was as low as 3.2%, the Young's modulus was as high as 120 GPa, and the maximum elastic strain was as small as 0.2%. In Comparative Example 4, the volume fraction of the β-phase was 95%, but the ratio of the corresponding grain boundary length was as low as 3.5%, the Young's modulus was as high as 105 GPa, and the maximum elastic strain was as small as 0.3%. In Comparative Example 5, the composition was not appropriate and the volume fraction of the β-phase was 0%. The Young's modulus was as high as 115 GPa, and the maximum elastic strain was as small as 0.1%. In Comparative Examples 6, 7, and 8, since the composition was not appropriate and a large amount of γ-phase appeared, both hot working and cold working were difficult, and it was impossible to fabricate the material.

[0079] On the other hand, in Examples 1-18 of the present invention, the volume fraction of the β-phase was 50% or more, the ratio of the corresponding grain boundary length was 4% or more, the Young's modulus was 100 GPa or less, and the maximum elastic strain was 0.4% or more and became large.

[0080] As a result of the above confirmation experiments, it was confirmed that according to the present invention, it is possible to provide a copper alloy that is excellent in conductivity, has a low Young's modulus, a sufficiently large elastic deformation amount, and is less likely to undergo plastic deformation even when subjected to a large deformation.

Claims

1. It contains Zn of 15% by mass or more and 57% by mass or less, contains Al of 12% by mass or less, sets the content of Zn as A% by mass and the content of Al as B% by mass, and satisfies A + 5×B ≥ 30 and A + 3.5×B ≤ 57, and the balance is made up of Cu and inevitable impurities, the volume fraction of the β phase is 50% or more, Measuring an area of 8 mm or more by the EBSD method at a measurement interval step of 8 μm, analyzing excluding measurement points where the CI value analyzed by data analysis software OIM is 0.1 or less, defining grain boundaries as the points where the azimuth difference between adjacent measurement points is 5° or more, and a copper alloy characterized in that the ratio of each corresponding grain boundary length of 3 ≦ Σ ≦ 29 to the total grain boundary length where the measured β phases are in contact is 4% or more. ２ ​

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

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

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

5. The copper alloy according to claim 1 or claim 2, wherein the ratio of the grain boundary length with an orientation difference of 20° or less at the grain boundary where β phases are in contact is 10% or more.

6. The copper alloy according to claim 1 or claim 2, wherein the maximum value of the intensity plot of the crystal orientation of the β phase in the processing direction obtained from the texture analysis by the EBSD method is 2 or more.

7. The copper alloy according to claim 1 or claim 2, wherein the maximum value of the intensity plot of the crystal orientation of the β phase exists within 30° of the azimuth from <001> or <101>.

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

9. The copper alloy according to claim 1 or claim 2, wherein the maximum elastic strain is 0.4% or more.

10. The copper alloy according to claim 1 or claim 2, wherein the conductivity is 10% IACS or more.

11. A copper alloy plastic working material, characterized by being made of the copper alloy according to claim 1 or claim 2.

12. Parts for electronic and electrical equipment, characterized by being made of the copper alloy according to claim 1 or claim 2.

13. Parts for flexible devices, characterized by being made of the copper alloy according to claim 1 or claim 2.

14. A heat dissipating component made of the copper alloy according to claim 1 or claim 2.

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

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