Copper alloy and component for electronic and electrical equipment

Abstract

A Cu-Fe-P-based copper alloy having a composition containing 1.5 mass% or more and 2.7 mass% or less of Fe, 0.008 mass% or more and 0.20 mass% or less of P, 0.01 mass% or more and 0.5 mass% or less of Zn, 0.01 mass% or more and 0.5 mass% or less of Sn, and the balance of Cu and unavoidable impurities, the conductivity in the direction parallel to the longitudinal direction being more excellent than the conductivity in the direction orthogonal to the longitudinal direction. The ratio [sigma] P / [sigma] O between the electrical conductivity [sigma] P measured in a direction parallel to the longitudinal direction and the electrical conductivity [sigma] O measured in a direction orthogonal to the longitudinal direction is greater than 100.1% and 105.0% or less, and when precipitate particles having a particle diameter of 150 nm or more and less than 1000 nm observed in a cross section including the longitudinal direction are used as objects, the particle diameter of the precipitate particles is less than or equal to 10 [sigma] P / [sigma] O, and the particle diameter of the precipitate particles is less than or equal to 10 [sigma] P / [sigma] O. The average value of the ratio LO / LP between the particle length LO in the direction orthogonal to the longitudinal direction and the particle length LP in the direction parallel to the longitudinal direction is 0.8 or less.

Description

Technical Field

[0001] The present invention relates to a copper alloy suitable for use in electrical and electronic equipment components such as household appliances, semiconductor components such as lead frames, printed wiring boards, heat sinks, switching device components, bus bars, and connectors, and electrical and electronic equipment components composed of the copper alloy.

[0002] This application claims priority based on patent application No. 2023-053123 applied for in Japan on March 29, 2023, and uses the content here. Background Art

[0003] Conventionally, copper or copper alloys, which have excellent electrical conductivity, have been used in components for electronic and electrical devices, such as terminals, bus bars, lead frames, and heat sinks.

[0004] As copper alloys for the various uses mentioned above, in the past, Cu-Fe-P alloys containing Fe and P were widely used. Cu-Fe-P alloys are precipitation-strengthened alloys formed by precipitating intermetallic compounds such as Fe or Fe-P in a copper matrix. Due to their excellent strength, electrical conductivity and thermal conductivity, they are widely used in various applications. In recent years, with the expansion of the use of Cu-Fe-P alloys, the lightweighting, thinning, miniaturization of electronic and electrical equipment, Cu-Fe-P alloys are also required to have further high strength, high electrical conductivity and good thermal conductivity. For example, in Patent Document 1, a Cu-Fe-P alloy in which the grains of the Cu matrix are equiaxed in order to reduce the anisotropy of mechanical properties is proposed.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-057116 (A)

[0006] For example, in applications such as busbars in electrical and electronic equipment components, where current flows in a specific direction, electrical conductivity in the longitudinal direction is particularly required. However, no thorough research has been conducted on the anisotropy of electrical conductivity in conventional Cu-Fe-P alloys.

[0007] Patent Document 1 studies the anisotropy of properties, but the purpose is to reduce the anisotropy of mechanical properties and does not focus on electrical conductivity. Summary of the Invention

[0008] The present invention has been made in view of the above circumstances, and its object is to provide a Cu-Fe-P copper alloy having a higher electrical conductivity in a direction parallel to the longitudinal direction than in a direction perpendicular to the longitudinal direction, and a component for electronic and electrical equipment composed of the copper alloy.

[0009] In order to solve the above-mentioned problems, the copper alloy according to the first aspect of the present invention is characterized in that it contains 1.5 mass% to 2.7 mass% of Fe, 0.008 mass% to 0.20 mass% of P, 0.01 mass% to 0.5 mass% of Zn, and 0.01 mass% to 0.5 mass% of Sn, with the remainder being Cu and inevitable impurities, and has an electrical conductivity σ measured in a direction parallel to the longitudinal direction of the copper alloy. P and the conductivity σ measured in the direction perpendicular to the longitudinal direction O The ratio σ P / σ O When the particle diameter of the precipitate particles observed on the cross section including the longitudinal direction is 150 nm or more and less than 1000 nm, the particle length L in the direction perpendicular to the longitudinal direction is greater than 100.1% and less than 105.0%. O and the particle length L in the direction parallel to the longitudinal direction P Ratio L O / L P The average value is below 0.8.

[0010] The copper alloy according to aspect 1 of the present invention has a composition containing 1.5 mass% to 2.7 mass% of Fe, 0.008 mass% to 0.20 mass% of P, 0.01 mass% to 0.5 mass% of Zn, and 0.01 mass% to 0.5 mass% of Sn, with the remainder being Cu and unavoidable impurities. Therefore, the copper alloy has excellent strength and electrical conductivity while being able to have good thermal conductivity.

[0011] Furthermore, in the copper alloy of the first aspect of the present invention, the electrical conductivity σ measured in a direction parallel to the longitudinal direction is P and the conductivity σ measured in the direction perpendicular to the longitudinal direction O The ratio σ P / σ O Since the conductivity is greater than 100.1% and less than 105.0%, the conductive material has excellent conductivity particularly in applications where electric current is allowed to flow in the longitudinal direction.

[0012] Furthermore, the precipitate particles are an obstacle to the electrons flowing through the matrix and become a factor of resistance. O and the particle length L in the direction parallel to the longitudinal direction P When different, the conductivity becomes anisotropic.

[0013] Thus, by controlling the morphology of the precipitates, the conductivity in the longitudinal direction can be improved. On the other hand, in order to obtain the particle length L in the direction perpendicular to the longitudinal direction Oand the particle length L in the direction parallel to the longitudinal direction P Ratio L O / L P Small precipitates require coarse precipitates, which can cause surface defects. In addition, small precipitates are mostly spherical and have little effect on anisotropy.

[0014] Therefore, in the copper alloy of the first aspect of the present invention, when the precipitate particles having an observed particle size of 150 nm or more and less than 1000 nm are taken as objects, the particle length L in the direction perpendicular to the longitudinal direction is O and the particle length L in the direction parallel to the longitudinal direction P Ratio L O / L P The average value of is 0.8 or less, which can improve the electrical conductivity in the longitudinal direction and suppress surface defects.

[0015] In addition, the particle size of the precipitate particles in the present invention is the diameter of a circle having an area equal to the area of ​​the precipitate particles in microstructure observation (equivalent circle diameter), and the precipitate particle length in the direction parallel to the longitudinal direction and the direction perpendicular to the longitudinal direction is the length of the precipitate particles measured in these directions.

[0016] The copper alloy of the second aspect of the present invention is characterized in that, in the copper alloy of the first aspect of the present invention, the electrical resistance ratio R P The resistance ratio R measured in the direction perpendicular to the longitudinal direction O Ratio R P / R O More than 100.1% and 105.0% or less.

[0017] According to the copper alloy of aspect 2 of the present invention, the electrical resistance ratio R measured in a direction parallel to the longitudinal direction is P The resistance ratio R measured in the direction perpendicular to the longitudinal direction O R P / R O When the content is greater than 100.1% and less than 105.0%, the electrical conductivity in the longitudinal direction is excellent even at low temperatures.

[0018] The resistance ratio (R) was calculated by measuring the resistivity at 293 K (ρ293 K) and the resistivity at liquid nitrogen temperature (77 K) (ρ77 K) and using R=ρ293 K / ρ77 K.

[0019] The copper alloy according to claim 3 of the present invention is characterized by further containing one or both of 0.005 mass % to 0.5 mass % of Mg and 0.005 mass % to 0.5 mass % of Co in the copper alloy according to claim 1 or 2 of the present invention.

[0020] According to aspect 3 of the present invention, the copper alloy also contains either or both of 0.005 mass % and less than 0.5 mass % of Mg and 0.005 mass % and less than 0.5 mass % of Co, so that Mg and Co are solid-dissolved in the parent phase and partially solid-dissolved in Fe-based and Fe-P-based precipitates, thereby improving heat resistance and strength through solid solution strengthening and partial precipitation strengthening.

[0021] 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, any one or two or more of 0.005 mass % to 0.5 mass % of Ni, 0.005 mass % to 0.5 mass % of Al, and 0.005 mass % to 0.5 mass % of Si are further contained.

[0022] According to the copper alloy of aspect 4 of the present invention, since it further contains any one or two or more of 0.005 mass % to 0.5 mass % of Ni, 0.005 mass % to 0.5 mass % of Al, and 0.005 mass % to 0.5 mass % of Si, heat resistance and strength can be further improved.

[0023] The copper alloy according to claim 5 of the present invention is the copper alloy according to any one of claims 1 to 4 of the present invention, wherein the electrical conductivity in a direction parallel to the longitudinal direction is 55% IACS or higher.

[0024] According to the copper alloy of the fifth aspect of the present invention, since the electrical conductivity in the direction parallel to the longitudinal direction is 55% IACS or higher, it can be suitably used also in applications requiring high electrical conductivity.

[0025] The copper alloy according to aspect 6 of the present invention is characterized in that, in the copper alloy according to any one of aspects 1 to 5 of the present invention, the content of C contained as the unavoidable impurities is less than 5 mass ppm, the content of Cr is less than 7 mass ppm, the content of Mo is less than 5 mass ppm, the content of W is less than 1 mass ppm, the content of V is less than 1 mass ppm, and the content of Nb is less than 1 mass ppm.

[0026] According to the copper alloy of the sixth aspect of the present invention, since the elements that promote liquid phase separation during melting and casting are reduced, the formation of coarse Fe-based crystals in the ingot can be suppressed and the number of generated surface defects can be reduced.

[0027] A seventh aspect of the present invention provides an electrical and electronic device component comprising the copper alloy according to any one of the first to sixth aspects of the present invention.

[0028] According to the seventh aspect of the present invention, the component for an electronic or electrical device is composed of the copper alloy according to any one of the first to sixth aspects of the present invention, and therefore can exhibit excellent characteristics even in a high-temperature environment.

[0029] The present invention can provide a Cu-Fe-P based copper alloy having a higher electrical conductivity in a direction parallel to the longitudinal direction than in a direction perpendicular to the longitudinal direction, and a component for electronic and electrical devices comprising the copper alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is an observation photograph showing an example of precipitate particles of the copper alloy according to the present embodiment.

[0031] Figure 2 This is a flowchart of the method for producing a copper alloy according to the present embodiment. DETAILED DESCRIPTION

[0032] Hereinafter, a copper alloy according to an embodiment of the present invention will be described.

[0033] The copper alloy of this embodiment contains 1.5% to 2.7% by mass of Fe, 0.008% to 0.20% by mass of P, 0.01% to 0.5% by mass of Zn, and 0.01% to 0.5% by mass of Sn, with the remainder being Cu and unavoidable impurities.

[0034] Furthermore, the copper alloy of the present embodiment may further contain either or both of 0.005 mass % to 0.5 mass % of Mg and 0.005 mass % to 0.5 mass % of Co.

[0035] Furthermore, the copper alloy of the present embodiment may further contain any one or two or more of 0.005 mass % to 0.5 mass % Ni, 0.005 mass % to 0.5 mass % Al, and 0.005 mass % to 0.5 mass % Si.

[0036] Moreover, in the copper alloy of this embodiment, it is preferred that the content of C contained as the unavoidable impurities is less than 5 mass ppm, the content of Cr is less than 7 mass ppm, the content of Mo is less than 5 mass ppm, the content of W is less than 1 mass ppm, the content of V is less than 1 mass ppm, and the content of Nb is less than 1 mass ppm.

[0037] Furthermore, in the copper alloy of this embodiment, the electrical conductivity σ measured in a direction parallel to the longitudinal direction is P and the conductivity σ measured in the direction perpendicular to the longitudinal direction O The ratio σ P / σ O More than 100.1% and 105.0% or less.

[0038] Furthermore, in the copper alloy of this embodiment, Figure 1 As shown, when the precipitate particles 12 having a particle diameter of 150 nm or more and less than 1000 nm observed in a cross section including the longitudinal direction are taken as the object, the particle length in the direction perpendicular to the longitudinal direction (particle diameter in the longitudinal direction perpendicular to the longitudinal direction) L O and the particle length in the direction parallel to the longitudinal direction (particle diameter in the direction parallel to the longitudinal direction) L P Ratio L O / L P The average value is below 0.8.

[0039] That is, in the copper alloy of this embodiment, if Figure 1 As shown, precipitate particles 12 such as Fe and Fe-P are dispersed in the matrix 11, and the particle size of the precipitate particles 12 is determined as described above. The matrix 11 refers to a phase other than the precipitate particles 12 such as Fe and Fe-P, and is a phase having Cu as the main component (Cu content exceeding 97% by mass) and having a portion of Fe, Zn, P, Sn, etc. solid-dissolved therein.

[0040] Here, small precipitates with a particle size of less than 150 nm are mostly spherical and have little effect on anisotropy, so they are excluded. In addition, precipitate particles 12 with a particle size of more than 1000 nm may become the cause of surface defects and are therefore excluded. In addition, the particle size of the precipitate particles 12 in this embodiment is the diameter of a circle having an area equal to the area of ​​the precipitate particles 12 in the microstructure observation (equivalent circle diameter), and the particle length L in the direction perpendicular to the length direction is O and the particle length L in the direction parallel to the length direction P These are the lengths of the precipitate particles 12 measured in these directions.

[0041] Here, in the copper alloy of the present embodiment, the electrical conductivity in the direction parallel to the longitudinal direction is preferably 55% IACS or higher.

[0042] Furthermore, in the copper alloy of this embodiment, the strength is preferably 480 MPa or more.

[0043] Furthermore, in the copper alloy of the present embodiment, the Vickers hardness is preferably 100 HV or higher.

[0044] In the copper alloy of the present embodiment, the reasons why the component composition, various properties, and crystal structure are specified as described above will be described below.

[0045] (Fe)

[0046] While Fe is dissolved in the matrix 11, Fe or Fe-P precipitate particles 12 are generated. The dispersion of these Fe or Fe-P precipitate particles 12 in the matrix 11 improves strength, hardness, and heat resistance without reducing electrical conductivity. Here, when the Fe content is less than 1.5% by mass, the effect of improving strength is insufficient. On the other hand, if the Fe content exceeds 2.7% by mass, larger crystals may be generated, impairing surface cleanliness. Furthermore, this may lead to a decrease in electrical conductivity and workability.

[0047] Therefore, in the present embodiment, the Fe content is set to 1.5 mass % or more and 2.7 mass % or less.

[0048] In order to reliably exert the above-mentioned effects, the lower limit of the Fe content is preferably set to 1.8 mass% or more, more preferably 2.1 mass% or more. Furthermore, in order to reliably suppress the formation of large crystals, the upper limit of the Fe content is preferably set to 2.6 mass% or less, more preferably 2.4 mass% or less.

[0049] (P)

[0050] P is an element with a deoxidizing effect. Furthermore, as described above, it forms Fe-P precipitate particles 12 together with Fe, improving strength, hardness, and heat resistance without reducing electrical conductivity. However, if the P content is less than 0.008 mass%, the effect of improving strength and other properties is insufficient. On the other hand, if the P content exceeds 0.20 mass%, electrical conductivity and workability are reduced.

[0051] Therefore, in the present embodiment, the P content is set to 0.008 mass % or more and 0.20 mass % or less.

[0052] In order to reliably exert the above-mentioned effects, the lower limit of the P content is preferably set to 0.01 mass% or more, more preferably 0.02 mass% or more. Furthermore, in order to reliably suppress the reduction of electrical conductivity and processability, the upper limit of the P content is preferably set to 0.19 mass% or less, more preferably 0.15 mass% or less, and particularly preferably 0.12 mass% or less.

[0053] (Zn)

[0054] Zn is an element that improves solder wettability and solder weathering resistance. When the Zn content is less than 0.01% by mass, these effects are not fully realized. On the other hand, even when the Zn content exceeds 0.5% by mass, these effects are saturated.

[0055] Therefore, in the present embodiment, the Zn content is set to 0.01 mass % or more and 0.5 mass % or less.

[0056] In order to reliably exert the above-mentioned effects, the lower limit of the Zn content is preferably set to 0.02 mass% or more, more preferably 0.05 mass% or more, and particularly preferably 0.07 mass% or more. Furthermore, the upper limit of the Zn content is preferably set to 0.44 mass% or less, more preferably 0.35 mass% or less, and particularly preferably 0.20 mass% or less.

[0057] (Sn)

[0058] Sn is an element that improves heat resistance and strength by forming a solid solution in the matrix 11. When the Sn content is less than 0.01 mass%, these effects cannot be fully realized. On the other hand, when the Sn content exceeds 0.5 mass%, the electrical conductivity decreases significantly.

[0059] Therefore, in this embodiment, the content of Sn is set to 0.01 mass % or more and 0.5 mass % or less.

[0060] In addition, in order to reliably exert the above-mentioned effects, the lower limit of the Sn content is preferably set to 0.02 mass % or more, more preferably set to 0.03 mass % or more. Moreover, in order to further suppress the reduction of electrical conductivity, the upper limit of the Sn content is preferably set to 0.3 mass % or less, more preferably set to 0.2 mass % or less.

[0061] (Mg, Co)

[0062] Mg and Co have the effect of solid-solution strengthening in the matrix 11, thereby improving heat resistance and strength. Therefore, they can be appropriately added according to the required characteristics. Here, when the Mg content is less than 0.005 mass% or the Co content is less than 0.005 mass%, the above-mentioned effects cannot be fully exerted. On the other hand, when the Mg content exceeds 0.5 mass% or the Co content exceeds 0.5 mass%, the electrical conductivity will be significantly reduced.

[0063] Therefore, in the present embodiment, when Mg and Co are added, it is preferable to set the Mg content to 0.005 mass % or more and 0.5 mass % or less, and the Co content to 0.005 mass % or more and 0.5 mass % or less.

[0064] Here, when Mg and Co are added, the lower limit of the Mg content is preferably set to 0.01 mass% or more, and the lower limit of the Co content is preferably set to 0.01 mass% or more. Furthermore, the lower limit of the Mg content is preferably set to 0.02 mass% or more, and the lower limit of the Co content is preferably set to 0.02 mass% or more. Furthermore, the upper limit of the Mg content is preferably set to 0.2 mass% or less, and the upper limit of the Co content is preferably set to 0.2 mass% or less.

[0065] When Mg and Co are contained as impurities, they may be contained in an amount lower than the above-mentioned lower limit.

[0066] (Ni, Al, Si)

[0067] Ni, Al, and Si have the effect of further improving heat resistance and strength. Therefore, they can be added appropriately according to the required characteristics. Here, when the Ni content is less than 0.005 mass%, the Al content is less than 0.005 mass%, or the Si content is less than 0.005 mass%, the above effects cannot be fully exerted. On the other hand, when the Ni content is greater than 0.5 mass%, the Al content is greater than 0.5 mass%, or the Si content is greater than 0.5 mass%, the electrical conductivity will be significantly reduced.

[0068] Therefore, in this embodiment, when Ni, Al, and Si are added, it is preferred to set the Ni content to 0.005 mass% or more and 0.5 mass% or less, the Al content to 0.005 mass% or more and 0.5 mass% or less, and the Si content to 0.005 mass% or more and 0.5 mass% or less.

[0069] Here, when Ni, Al, and Si are added, the lower limit of the Ni content is preferably set to 0.01 mass % or more, the lower limit of the Al content is preferably set to 0.01 mass % or more, and the lower limit of the Si content is preferably set to 0.01 mass % or more. Furthermore, the upper limit of the Ni content is preferably set to 0.1 mass % or less, the upper limit of the Al content is preferably set to 0.1 mass % or less, and the upper limit of the Si content is preferably set to 0.1 mass % or less.

[0070] When Ni, Al, and Si are contained as impurities, they may be contained in an amount less than the above-mentioned lower limit.

[0071] (C, Cr, Mo, W, V, Nb as unavoidable impurities)

[0072] The copper alloys described above contain C, Cr, Mo, W, V, and Nb as unavoidable impurities. High levels of C, Cr, Mo, W, V, and Nb significantly increase surface defects in the copper alloy sheet. These surface defects are caused by iron alloy particles containing at least one of Cr, Mo, W, V, and Nb, as well as Fe and C.

[0073] Usually, when smelting and casting the above-mentioned copper alloy, the Fe element exists in the state of being dissolved in the liquid phase based on Cu. However, when C, Cr, Mo, W, V, Nb exist in a certain amount or more, the copper alloy melt is separated into a liquid phase based on Cu and a liquid phase based on Fe and containing at least one of C and Cr, Mo, W, V and Nb. As a result, there is a coarse crystallized substance containing at least one of Cr, Mo, W, V and Nb, Fe and C in the ingot. It is believed that by rolling the ingot thereafter, the iron alloy particles are exposed and produce the above-mentioned surface defects on the surface of the copper alloy sheet. And, the iron alloy particles can cause poor shape when punching, etching or silver plating.

[0074] From the above, it can be seen that surface defects and poor product shape caused by iron alloy particles can be suppressed by reducing C, Cr, Mo, W, V, and Nb.

[0075] Therefore, in this embodiment, in order to suppress the formation of coarse crystals, it is preferred to limit the content of C as an inevitable impurity to less than 5 mass ppm, the content of Cr to less than 7 mass ppm, the content of Mo to less than 5 mass ppm, the content of W to less than 1 mass ppm, the content of V to 1 mass ppm, and the content of Nb to less than 1 mass ppm.

[0076] Furthermore, in order to further suppress the generation of coarse crystals, the content of C as an inevitable impurity is preferably set to less than 4 mass ppm, more preferably to 3 mass ppm or less, and even more preferably to 2 mass ppm or less.

[0077] Furthermore, the content of Mo as an unavoidable impurity is preferably set to less than 1 mass ppm, and more preferably set to less than 0.6 mass ppm.

[0078] Furthermore, it is preferable that the content of Cr as an inevitable impurity be set to less than 5 mass ppm, the content of W be set to less than 0.6 mass ppm, the content of V be set to less than 0.6 mass ppm, and the content of Nb be set to less than 0.6 mass ppm.

[0079] In addition, examples of inevitable impurities other than the above-mentioned elements and C, Cr, Mo, W, V, and Nb include Ca, Sr, Ba, rare earth elements, Zr, Be, Ti, H, Li, B, N, O, F, Na, S, Cl, K, Mn, Ga, Ge, As, Se, Br, Rb, Tc, Ru, Rh, Pd, Ag, Cd, In, Sb, Te, I, Cs, Hf, Ta, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, and Bi. These inevitable impurities may be contained within a range that does not affect the characteristics.

[0080] Since these inevitable impurities may reduce the electrical conductivity, the total amount is preferably set to 0.1 mass % or less, more preferably to 0.05 mass % or less, more preferably to 0.03 mass % or less, and even more preferably to 0.01 mass % or less.

[0081] (Ratio of particle length of precipitate particles)

[0082] The precipitate particles 12 become an obstacle for the electrons flowing through the matrix 11. Therefore, the particle length L in the direction perpendicular to the longitudinal direction is O and the particle length L in the direction parallel to the longitudinal direction P On the other hand, in order to obtain the particle length L in the direction perpendicular to the longitudinal direction, O and the particle length L in the direction parallel to the longitudinal direction P Ratio L O / L P Small precipitates require coarse precipitates, which can cause surface defects. In addition, small precipitates are mostly spherical and have little effect on anisotropy.

[0083] Therefore, in the present embodiment, when the precipitate particles 12 having a particle diameter of 150 nm or more and less than 1000 nm observed in a cross section including the longitudinal direction are taken as the object, the particle length L of the precipitate particles 12 in a direction perpendicular to the longitudinal direction is taken as O and the particle length L in the direction parallel to the longitudinal direction P Ratio L O / L P The average value is set to be less than 0.8.

[0084] In order to achieve the above-mentioned effects, the particle length ratio L of the precipitate particles 12 should be O / L P The average value of is preferably set to 0.75 or less, more preferably to 0.7 or less.

[0085] (Conductivity)

[0086] The copper alloy of this embodiment, when having an electrical conductivity of 55% IACS or greater in a direction parallel to the longitudinal direction, is particularly suitable as a material for components of electrical and electronic equipment such as busbars. Furthermore, the copper alloy of this embodiment preferably has an electrical conductivity of 57% IACS or greater in a direction parallel to the longitudinal direction, and more preferably has an electrical conductivity of 60% IACS or greater.

[0087] Furthermore, in the copper alloy of this embodiment, the electrical conductivity σ measured in a direction parallel to the longitudinal direction is P and the conductivity σ measured in the direction perpendicular to the longitudinal direction O The ratio σ P / σ O When the conductivity is greater than 100.1%, it is particularly suitable as a material for components of electrical and electronic equipment such as busbars that allow current to flow in a specific direction. On the other hand, in order to increase the conductivity σ measured in the direction parallel to the longitudinal direction, P and the conductivity σ measured in the direction perpendicular to the longitudinal direction O The ratio σ P / σ O , precipitates with high aspect ratios are required, but such precipitates are coarse and may cause surface defects.

[0088] Therefore, in the copper alloy of this embodiment, the electrical conductivity σ measured in the direction parallel to the longitudinal direction is P and the conductivity σ measured in the direction perpendicular to the longitudinal direction O The ratio σ P / σ O More than 100.1% and 105.0% or less.

[0089] In addition, the electrical conductivity σ measured in the direction parallel to the longitudinal direction P and the conductivity σ measured in the direction perpendicular to the longitudinal direction O The ratio σ P / σ O The lower limit of is preferably 100.2% or more, more preferably 100.3% or more. The electrical conductivity σ measured in the direction parallel to the longitudinal direction is P and the conductivity σ measured in the direction perpendicular to the longitudinal direction O The ratio σ P / σ O The upper limit of is preferably 103.0% or less, more preferably 102.0% or less.

[0090] (Resistance ratio (R))

[0091] In the copper alloy of this embodiment, if the resistance ratio (R), which is an indicator of electrical conductivity at low temperatures, is higher when measured in a direction parallel to the longitudinal direction than when measured in a direction perpendicular to the longitudinal direction, the copper alloy is particularly suitable as a material for components of electrical and electronic equipment such as busbars that allow current to flow in a specific direction even at low temperatures. That is, the resistance ratio R measured in a direction parallel to the longitudinal direction is higher than the value measured in a direction perpendicular to the longitudinal direction. P The resistance ratio R measured in the direction perpendicular to the longitudinal direction O Ratio R P / R O On the other hand, in order to increase the resistance ratio R measured in the direction parallel to the longitudinal direction, P The resistance ratio R measured in the direction perpendicular to the longitudinal direction O Ratio R P / R O , precipitates with high aspect ratios are required, but such precipitates are coarse and may cause surface defects.

[0092] Therefore, it is preferable that the resistance R measured in a direction parallel to the longitudinal direction is P The resistance ratio R measured in the direction perpendicular to the longitudinal direction O Ratio R P / R O More than 100.1% and 105.0% or less.

[0093] In addition, the resistance R measured in the direction parallel to the longitudinal direction is P The resistance ratio R measured in the direction perpendicular to the longitudinal direction O Ratio R P / R O The lower limit of is preferably 100.2% or more, more preferably 100.3% or more. The resistance ratio R measured in the direction parallel to the longitudinal direction is P The resistance ratio R measured in the direction perpendicular to the longitudinal direction O Ratio R P / R O The upper limit of is preferably 103.0% or less, more preferably 102.0% or less.

[0094] (Tensile Strength)

[0095] The copper alloy of this embodiment has excellent strength when the tensile strength is 400 MPa or more, and is particularly suitable as a material for components of electrical and electronic equipment such as busbars. In this embodiment, the tensile strength when subjected to a tensile test in a direction parallel to the rolling direction is 400 MPa or more.

[0096] Furthermore, the tensile strength of the copper alloy of the present embodiment is more preferably 415 MPa or more, and more preferably 430 MPa or more.

[0097] (Vickers hardness)

[0098] The copper alloy of the present embodiment has a Vickers hardness of 100 HV or higher and is less likely to deform, and is particularly suitable as a material for components of electrical and electronic equipment such as bus bars.

[0099] Furthermore, the Vickers hardness of the copper alloy of the present embodiment is preferably 110 HV or higher, and more preferably 120 HV or higher.

[0100] Next, refer to Figure 2 An example of the method for producing the copper alloy according to the present embodiment will be described with reference to the flowchart shown in FIG.

[0101] (Melting / Casting Process S01)

[0102] First, the aforementioned elements are added to the copper melt obtained by smelting the copper raw material to adjust the composition and produce a copper alloy melt. Furthermore, when adding various elements, simple elements, master alloys, etc. can be used. Furthermore, raw materials containing the aforementioned elements can be smelted together with the copper raw material. Furthermore, recycled materials and scrap of the alloy can also be used. Here, the copper melt is preferably so-called 4NCu with a purity of 99.99% by mass or more, or so-called 5NCu with a purity of 99.999% by mass or more. Furthermore, the composition-adjusted copper alloy melt is poured into a casting mold to produce an ingot. Furthermore, considering mass production, a continuous casting method or a semi-continuous casting method is preferably used.

[0103] (Homogenization Step S02)

[0104] Next, the resulting ingot is heat treated to homogenize it. The ingot is preferably held at a temperature between 850°C and 1050°C for at least one hour. While there is no upper limit on the holding time in the homogenization step ( S02 ), it is preferably set to 24 hours or less for cost and manufacturing efficiency considerations. Furthermore, the cooling rate in the homogenization step ( S02 ) is not particularly limited; air cooling or water cooling may be employed.

[0105] (Hot working process S03)

[0106] Next, hot working is performed. This hot working step can also be combined with the homogenization step S02. After holding at 850°C to 1050°C for at least 1 hour, hot working is performed at 850°C to 1050°C, followed by water cooling.

[0107] Furthermore, in the hot working step S03 , the working method is not particularly limited, and for example, rolling, wire drawing, extrusion, groove rolling, forging, stamping, etc. can be employed. In the present embodiment, rolling is performed.

[0108] (Rough machining process S04)

[0109] After the hot working step S03, low-temperature rough machining is performed. During this machining process, the hot-worked material is immersed in liquid nitrogen for at least one minute, and machining is performed while the machining tool is cooled by the liquid nitrogen. The machining rate is preferably set within a range of 10% to 95%. This eliminates the heat generated by machining and performs machining at extremely low temperatures, suppressing recovery or recrystallization caused by machining heat. This allows precipitates to be machined at low temperatures, thereby reducing the particle length ratio of the precipitate particles 12.

[0110] In the rough working step S04 , the working method is not particularly limited, and for example, rolling, wire drawing, extrusion, groove rolling, forging, punching, etc. can be employed. In the present embodiment, rolling is performed.

[0111] (First Precipitation Heat Treatment Step S05)

[0112] Next, a heat treatment is performed at a temperature of 450°C to 600°C for more than 1 hour and less than 24 hours. Preferably, the holding time is shortened when the heat treatment is performed at a high temperature, and extended when the heat treatment is performed at a low temperature. This first precipitation heat treatment step S05 improves electrical conductivity.

[0113] The heating rate or cooling rate in the first precipitation heat treatment step S05 may be appropriately set. Preferably, the heating rate is set to 1°C / min or more, and the cooling rate is set to 0.1°C / min or more up to 300°C.

[0114] (First Cold Working Step S06)

[0115] After the first precipitation heat treatment step S05, the first cold working is implemented. In the processing at this time, the first precipitation heat treatment material is immersed in liquid nitrogen for more than 1 minute, and the processing tool is processed while being cooled by liquid nitrogen. The processing rate is preferably set in the range of more than 10% and less than 95%. Moreover, the processing rate is preferably set in the range of more than 20% and less than 95%, further preferably set in the range of more than 30% and less than 95%, and more preferably set in the range of more than 40% and less than 95%. By removing the heat caused by processing and processing at extremely low temperatures, the recovery or recrystallization caused by the processing heat is suppressed, and therefore the precipitate can be processed at low temperatures, so that the average value of the ratio of the particle length of the precipitate particles 12 can be made to be less than 0.8.

[0116] In the first cold working step S06 , the working method is not particularly limited, and for example, rolling, wire drawing, extrusion, groove rolling, forging, stamping, etc. can be employed. In the present embodiment, rolling is performed.

[0117] (Second Precipitation Heat Treatment Step S07)

[0118] Next, a heat treatment is performed at a temperature of 450°C to 600°C for more than 1 hour and less than 24 hours. Preferably, the hold time is shortened when performing heat treatment at high temperatures, and extended when performing heat treatment at low temperatures. This second precipitation heat treatment step S07 further improves electrical conductivity. Considering the conditions of subsequent steps, it is preferred that the electrical conductivity of the final product be set to 55% IACS or higher.

[0119] The heating rate or cooling rate in the second precipitation heat treatment step S07 may be appropriately set. Preferably, the heating rate is set to 1°C / min or more, and the cooling rate is set to 0.1°C / min or more up to 300°C.

[0120] (Finishing process S08)

[0121] After the second precipitation heat treatment step S07, finishing is performed, and the processing rate at this time is preferably set within the range of 10% to 95%.

[0122] In the finishing step S08 , the processing method is not particularly limited, and for example, rolling, wire drawing, extrusion, groove rolling, forging, punching, etc. can be employed. In the present embodiment, rolling is performed.

[0123] (Stress relief heat treatment step S09)

[0124] Next, if necessary, a stress relief heat treatment is performed at a temperature of 200°C to less than 700°C for a period of 1 second to less than 24 hours to eliminate residual stress generated in the finishing step S08. Preferably, the holding time is shortened when the heat treatment is performed at a high temperature, and extended when the heat treatment is performed at a low temperature.

[0125] The copper alloy of this embodiment is manufactured by the above-described steps. In this embodiment, rolling is performed as the working method in the finishing step S08, so that a copper alloy plate strip material having a predetermined plate thickness can be manufactured.

[0126] According to the copper alloy of the present embodiment constructed as described above, its composition contains 1.5 mass% to 2.7 mass% of Fe, 0.008 mass% to 0.20 mass% of P, 0.01 mass% to 0.5 mass% of Zn, and 0.01 mass% to 0.5 mass% of Sn, with the remainder being Cu and unavoidable impurities. Therefore, it has excellent strength and electrical conductivity and can have good thermal conductivity.

[0127] Furthermore, the electrical conductivity σ measured in the direction parallel to the longitudinal direction is P and the conductivity σ measured in the direction perpendicular to the longitudinal direction O The ratio σ P / σ O Since the conductivity is greater than 100.1% and less than 105.0%, the conductive material has excellent conductivity particularly in applications where electric current is allowed to flow in the longitudinal direction.

[0128] Furthermore, when the observed precipitate particles having a particle size of 150 nm or more and less than 1000 nm are taken as objects, the particle length L in the direction perpendicular to the longitudinal direction is O and the particle length L in the direction parallel to the longitudinal direction P Ratio L O / L P The average value of is 0.8 or less, so the electrical conductivity in the longitudinal direction can be improved.

[0129] Furthermore, in the copper alloy of this embodiment, the electrical resistance R P The resistance ratio R measured in the direction perpendicular to the longitudinal direction O R P / R O When the content is greater than 100.1% and less than 105.0%, the electrical conductivity in the longitudinal direction is excellent even at low temperatures. Therefore, the material is particularly suitable as a material for components of electronic and electrical devices used in low-temperature environments.

[0130] Furthermore, when the copper alloy of the present embodiment further contains either or both of 0.005 mass % to 0.5 mass % of Mg and 0.005 mass % to 0.5 mass % of Co, heat resistance and strength can be improved by solid solution strengthening.

[0131] Furthermore, when the copper alloy of this embodiment further contains any one or two or more of 0.005 mass % to 0.5 mass % Ni, 0.005 mass % to 0.5 mass % Al, and 0.005 mass % to 0.5 mass % Si, the heat resistance and strength can be further improved.

[0132] Moreover, in the copper alloy of the present embodiment, when the content of C included as an inevitable impurity is set to less than 5 mass ppm, the content of Cr is set to less than 7 mass ppm, the content of Mo is set to less than 5 mass ppm, the content of W is set to less than 1 mass ppm, the content of V is set to less than 1 mass ppm, and the content of Nb is set to less than 1 mass ppm, the elements that have the effect of promoting liquid phase separation in the melting / casting step S01 are reduced, the formation of coarse Fe-based crystals in the ingot can be suppressed, and the number of surface defects generated can be reduced.

[0133] Furthermore, in the copper alloy of the present embodiment, when the electrical conductivity in the direction parallel to the longitudinal direction is 55% IACS or higher, the copper alloy can also be used in applications requiring high electrical conductivity.

[0134] Furthermore, in the copper alloy of the present embodiment, when the tensile strength is 400 MPa or more, the copper alloy can be suitably used in applications requiring high strength.

[0135] Furthermore, the copper alloy of the present embodiment is less likely to deform when its Vickers hardness is 100 HV or higher, and is particularly suitable as a component for electrical and electronic equipment.

[0136] While the copper alloy according to the embodiment of the present invention has been described above, the present invention is not limited thereto and can be appropriately modified without departing from the technical concept of the present invention. In the above embodiment, an example of a method for manufacturing a copper alloy has been described, but the method for manufacturing a copper alloy is not limited to the method described in the embodiment, and an existing manufacturing method can be appropriately selected for manufacturing.

[0137] For example, in the present embodiment, rolling is performed as a processing method to obtain a copper alloy sheet and strip material composed of the copper alloy of the present invention, but when wire drawing, extrusion, groove rolling, etc. are performed as a processing method, a copper alloy wire rod composed of the copper alloy of the present invention can be obtained, and when forging or stamping is performed as a processing method, copper alloy parts of various shapes composed of the copper alloy of the present invention can be obtained.

[0138] Example

[0139] First, as part of the melting / casting process, a copper raw material composed of oxygen-free copper (ASTM B152C10100) with a purity of 99.99% or greater by mass was prepared. This raw material was placed in an alumina crucible and melted in a high-frequency melting furnace set to an Ar gas atmosphere. Fe, P, Zn, Sn, Mg, Al, Si, Co, and Ni were added to the resulting copper melt. These elements were added using a Cu master alloy. Thus, a copper alloy melt with the composition shown in Table 1 was melted and cast into a carbon mold to produce an ingot. The ingot size was set to approximately 25 mm thick, 70 mm wide, and 100 mm long.

[0140] Next, as a hot working step, the resulting ingot was heat treated at the hot rolling temperature listed in Table 2 for 4 hours, and then hot worked at 900°C until the thickness reached 12 mm. Reheating was performed as needed. After hot rolling, the ingot was water-cooled. Face milling was performed to remove the surface oxide film formed after hot rolling.

[0141] Next, as a rough working step, after being immersed in liquid nitrogen for 10 minutes or more, the obtained hot-rolled material was cold-rolled while the roll surface was cooled with liquid nitrogen until the thickness became 2 mm.

[0142] Next, as the first precipitation heat treatment step, an electric furnace was used to maintain a predetermined time between 1 hour and 24 hours at the heat treatment temperature described in Table 2, followed by air cooling, furnace cooling, or water cooling. Then, polishing was performed to remove the surface oxide film formed after the heat treatment.

[0143] Next, as a first cold working step, the sample was immersed in liquid nitrogen for 10 minutes or longer, and then cold rolled while the roll surface was cooled with liquid nitrogen until the thickness became 0.7 mm.

[0144] Next, as a second precipitation heat treatment step, an electric furnace was used to maintain the heat treatment temperature listed in Table 2 for a predetermined time period of 1 to 24 hours. After the heat treatment, the furnace was cooled to 300° C. and then air-cooled or water-cooled.

[0145] As a finishing step, cold rolling was performed until the thickness became 0.5 mm in Inventive Examples 1 to 11 and Comparative Examples 1 and 2, and cold rolling was performed until the thickness became 0.2 mm in Inventive Examples 12 to 22, thereby preparing samples for evaluation and measurement.

[0146] Thereafter, as shown in Table 2, some of the samples were subjected to stress relief heat treatment for 1 minute at the temperature described using a salt bath furnace to prepare samples for evaluation and measurement.

[0147] The copper alloys of Inventive Examples 1 to 22 and Comparative Examples 1 and 2 obtained as described above were evaluated as follows.

[0148] (Observation of precipitate particles)

[0149] The observation of the precipitate particles was carried out by the following method. The rolled surface, i.e., the ND surface, of the sample for evaluation and measurement was mechanically polished and finished to a mirror finish. Then, the surface was ion-milled using an IM-5000 manufactured by Hitachi High-Technologies Corporation using Ar ions at an accelerating voltage of 4.0 kV. The precipitate particles were observed using a field emission scanning electron microscope (SU7000 manufactured by Hitachi High-Technologies Corporation). The precipitate particles were observed at a viewing angle of 5000 times (approximately 450 μm). 2 ) were imaged, and only the precipitates were contrast-enhanced after image processing. From the contrast-enhanced images, the image analysis software "Win ROOF" was used to calculate the equivalent circle diameter based on the area of ​​the precipitates. Precipitate particles with a particle size of 150 nm or more and less than 1000 nm were selected as the subjects. The aspect ratio of each particle was calculated based on the length of the precipitate particle size in a direction perpendicular to the longitudinal direction and in a direction parallel to the longitudinal direction. The average value of the aspect ratios of the target particles was used as the ratio of the precipitate particle length. Observation was performed in three or more viewing fields.

[0150] (Conductivity)

[0151] A test piece measuring 10 mm wide and 350 mm long was collected from the evaluation sample, and the resistance was determined using the four-terminal method. Furthermore, the dimensions of the test piece were measured using a micrometer, and the volume of the test piece was calculated. Furthermore, the conductivity was determined based on the measured resistivity and the calculated volume. Furthermore, the test piece was collected so that its length direction was parallel to and perpendicular to the rolling direction. The measurement results are shown in Table 3.

[0152] (Resistance ratio (R))

[0153] Test pieces measuring 5 mm wide and 200 mm long were collected from the evaluation samples. The resistivity at 293 K (ρ293 K) and the resistivity at liquid nitrogen temperature (77 K) (ρ77 K) were measured using the four-probe method. R = ρ293 K / ρ77 K was calculated. The test pieces were collected with their longitudinal direction parallel to and perpendicular to the rolling direction. The evaluation results are shown in Table 3.

[0154] (Tensile Strength)

[0155] In accordance with JIS Z 2241, a No. 13B test piece was collected from the sample and its tensile strength was measured. The test piece was collected so that the tensile direction was parallel to the rolling direction. The evaluation results are shown in Table 3.

[0156] (Vickers hardness)

[0157] The Vickers hardness was measured in accordance with the micro Vickers hardness test method specified in JIS Z 2244 at a test load of 0.98 N. The evaluation results are shown in Table 3.

[0158]

[0159] [Table 2]

[0160]

[0161] [Table 3]

[0162]

[0163] In Comparative Example 1, the first cold working step was performed at room temperature, so the average value of the particle length ratio was large, 0.86, and the anisotropy was also small.

[0164] Since the rough processing step was performed at room temperature in Comparative Example 2, the average value of the particle length ratio was large, 0.88, and the anisotropy was also small.

[0165] In contrast, in the examples of the present invention, it was confirmed that the electrical conductivity in the direction parallel to the longitudinal direction was superior to the electrical conductivity in the direction perpendicular to the longitudinal direction. Furthermore, the tensile strength, electrical conductivity, and Vickers hardness were also excellent. Based on the above, according to the examples of the present invention, it was confirmed that a Cu-Fe-P copper alloy having an electrical conductivity in the direction parallel to the longitudinal direction was superior to the electrical conductivity in the direction perpendicular to the longitudinal direction could be provided.

[0166] Industrial applicability

[0167] According to the present invention, it is possible to provide a Cu-Fe-P based copper alloy having electrical conductivity in a direction parallel to the longitudinal direction that is superior to electrical conductivity in a direction perpendicular to the longitudinal direction.

[0168] Explanation of symbols

[0169] 11 Mother Phase

[0170] 12 precipitate particles

[0171] L O Particle size in the length-orthogonal direction

[0172] L P Particle diameter parallel to the length

Claims

1. A copper alloy, characterized in that The copper alloy comprises 1.5% to 2.7% by mass of Fe, 0.008% to 0.20% by mass of P, 0.01% to 0.5% by mass of Zn, and 0.01% to 0.5% by mass of Sn, with the remainder being Cu and unavoidable impurities. The electrical conductivity σ measured in the direction parallel to the longitudinal direction P and the conductivity σ measured in the direction perpendicular to the longitudinal direction O The ratio σ P / σ O Greater than 100.1% and less than 105.0%, When the precipitate particles with a particle size of 150 nm or more and less than 1000 nm observed in a cross section including the longitudinal direction are taken as the object, the particle length L in the direction perpendicular to the longitudinal direction is O and the particle length L in the direction parallel to the longitudinal direction P Ratio L O / L P The average value is below 0.

8.

2. The copper alloy according to claim 1, characterized in that The resistance ratio R measured in the direction parallel to the length direction P The resistance ratio R measured in the direction perpendicular to the longitudinal direction O Ratio R P / R O More than 100.1% and 105.0% or less.

3. The copper alloy according to claim 1, wherein It further contains either or both of 0.005 mass % to 0.5 mass % of Mg and 0.005 mass % to 0.5 mass % of Co.

4. The copper alloy according to claim 1, wherein It further contains any one or two or more of 0.005 mass % to 0.5 mass % of Ni, 0.005 mass % to 0.5 mass % of Al, and 0.005 mass % to 0.5 mass % of Si.

5. The copper alloy according to claim 1, wherein The electrical conductivity in the direction parallel to the longitudinal direction is 55% IACS or higher.

6. The copper alloy according to claim 1, characterized in that The unavoidable impurities include C content less than 5 mass ppm, Cr content less than 7 mass ppm, Mo content less than 5 mass ppm, W content less than 1 mass ppm, V content less than 1 mass ppm, and Nb content less than 1 mass ppm.

7. A component for electronic and electrical equipment, characterized in that: Composed of the copper alloy according to any one of claims 1 to 6.

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