Copper alloy for electric and electronic devices, copper alloy sheet for electric and electronic devices, component for electric and electronic devices, terminal, and bus bar

Abstract

Provided are a copper alloy for electric and electronic devices, a copper alloy sheet for electric and electronic devices, a component for electric and electronic devices, a terminal, and a bus bar. The copper alloy for electric and electronic devices includes, as a composition: 0.01 mass % or higher and lower than 0.11 mass % of Zr; 0.002 mass % or higher and lower than 0.03 mass % of Si; and a balance including Cu and unavoidable impurities, in which a ratio Zr/Si of the Zr content (mass %) to the Si content (mass %) is within a range of 2 to 30.

Claims

1. A copper alloy sheet for electric and electronic devices, wherein a composition of the copper alloy sheet consists of: 0.01 mass % or higher and lower than 0.11 mass % of Zr; 0.002 mass % or higher and lower than 0.03 mass % of Si; and a balance including Cu and unavoidable impurities, a ratio Zr/Si of a mass % of Zr to a mass % of Si is within a range of 2 to 30, CuZrSi particles are dispersed in a matrix of copper, at least a part of the CuZrSi particles have a particle size of 1 nm to 500 nm, and the copper alloy sheet has a surface Vickers hardness of 153 HV or higher.

2. The copper alloy sheet for electric and electronic devices according to claim 1, wherein electrical conductivity is 80% IACS or higher.

3. The copper alloy sheet for electric and electronic devices according to claim 1, wherein 0.2% yield strength is 300 MPa or higher.

4. The copper alloy sheet for electric and electronic devices according to claim 1, wherein the copper alloy sheet is a rolled material with a thickness in a range of 0.05 mm to 1.0 mm.

5. The copper alloy sheet for electric and electronic devices according to claim 1, wherein a surface is plated with Sn or Ag.

6. A component for electric and electronic devices, the component comprising: the copper alloy sheet for electric and electronic devices according to claim 1.

7. A terminal comprising: the copper alloy sheet for electric and electronic devices according to claim 1.

8. A bus bar comprising: the copper alloy sheet for electric and electronic devices according to claim 1.

9. The copper alloy sheet for electric and electronic devices according to claim 1, wherein the copper alloy is produced from an ingot made of a molten copper alloy, and the ingot undergoes a heat treatment step where the ingot is heated at 960 C. to 1080 C. for four hours for solutionization.

10. The copper alloy sheet for electric and electronic devices according to claim 9, wherein immediately after the heat treatment step, the copper alloy undergoes a hot working step for homogenization where the copper alloy is worked to form a final shaper at 500 C. to 1050 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flow chart showing a process example of a copper alloy for electric and electronic devices according to an embodiment of the present invention.

(2) FIG. 2 is a structural image of a portion containing a precipitate in an alloy according to Example No. 5 when observed with a transmission electron microscope (TEM) at a magnification of 20,000 times.

(3) FIG. 3A is a structural image of the portion containing a precipitate in the alloy according to Example No. 5 when observed with a transmission electron microscope (TEM) at a magnification of 100,000 times.

(4) FIG. 3B is a graph showing the results of analyzing particles observed in FIG. 3A with energy dispersive X-ray spectroscopy (EDX).

DETAILED DESCRIPTION OF THE INVENTION

(5) Hereinafter, a copper alloy for electric and electronic devices according to an embodiment of the present invention will be described.

(6) The copper alloy for electric and electronic devices according to the embodiment includes, as a composition: 0.01 mass % or higher and lower than 0.11 mass % of Zr; 0.002 mass % or higher and lower than 0.03 mass % of Si; and a balance including Cu and unavoidable impurities, in which a ratio Zr/Si of the Zr content (mass %) to the Si content (mass %) is within a range of 2 to 30.

(7) The copper alloy for electric and electronic devices according to the embodiment may further include 0.005 mass % to 0.1 mass % in total of one element or two or more elements selected from the group consisting of Ag, Sn, Al, Ni, Zn, and Mg.

(8) In addition, the copper alloy for electric and electronic devices according to the embodiment may further include 0.005 mass % to 0.1 mass % in total of one element or two or more elements selected from the group consisting of Ti, Co, and Cr.

(9) Further, the copper alloy for electric and electronic devices according to the embodiment may further include 0.005 mass % to 0.1 mass % in total of one element or two or more elements selected from the group consisting of P, Ca, Te, and B.

(10) The copper alloy for electric and electronic devices according to the embodiment includes CuZrSi particles containing Cu, Zr, and Si. As the CuZrSi particles, relatively coarse particles having a particle size of 1 m to 50 m and fine particles having a particle size of 1 nm to 500 nm are present.

(11) In the copper alloy for electric and electronic devices, electrical conductivity is 80% IACS or higher, 0.2% yield strength is 300 MPa or higher, and surface Vickers hardness is 100 HV or higher.

(12) The upper limit value of the 0.2% yield strength is not particularly limited but can be set to 750 MPa. In addition, the upper limit value of the surface Vickers hardness is not particularly limited and can be set to be 250 HV.

(13) Hereinafter, the reason for specifying the component composition, the structure, and the like as described above will be described below.

(14) (Zr)

(15) Zr is an element that constitutes the above-described CuZrSi particle and has an effect of improving the yield strength while maintaining the electrical conductivity or an effect of improving the electrical conductivity while maintaining the yield strength. In addition, the Vickers hardness can be improved.

(16) Here, when the Zr content is lower than 0.01 mass %, the effects cannot be sufficiently exhibited. On the other hand, when the Zr content is 0.11 mass % or higher, the electrical conductivity may significantly decrease, and solutionization is difficult to perform, which may cause defects such as disconnection or cracking during hot working or cold working.

(17) From these points of view, in the embodiment, the Zr content is set to be within a range of 0.01 mass % or higher and lower than 0.11 mass %. In order to secure the number of CuZrSi particles to reliably improve the strength, the Zr content is preferably 0.04 mass % or higher, and is more preferably 0.05 mass % or higher. In addition, in order to reliably suppress, for example, an increase in the electrical conductivity and defects during working, the Zr content is preferably 0.10 mass % or lower.

(18) (Si)

(19) Si is an element that constitutes the above-described CuZrSi particle and has an effect of improving the yield strength while maintaining the electrical conductivity or an effect of improving the electrical conductivity while maintaining the yield strength. In addition, the Vickers hardness can be improved.

(20) Here, when the Si content is lower than 0.002 mass %, the effects cannot be sufficiently exhibited. On the other hand, when the Si content is 0.03 mass % or higher, the electrical conductivity may significantly decrease.

(21) From these points of view, in the embodiment, the Si content is set to be within a range of 0.002 mass % or higher and lower than 0.03 mass %. In order to secure the number of CuZrSi particles to reliably improve the strength, the Si content is preferably 0.003 mass % or higher, and is more preferably 0.004 mass % or higher. In addition, in order to reliably suppress an increase in the electrical conductivity, the Si content is preferably 0.025 mass % or lower, and is more preferably 0.02 mass % or lower.

(22) (Zr/Si)

(23) As described above, the CuZrSi particles are formed by adding Zr and Si to Cu. As a result, the yield strength can be improved while maintaining the electrical conductivity, or the electrical conductivity can be improved while maintaining the yield strength. In addition, the Vickers hardness can be improved.

(24) Here, when the ratio Zr/Si of the Zr content (mass %) to the Si content (mass %) is lower than 2, the Si content is higher than the Zr content. Therefore, the electrical conductivity may decrease due to an excess amount of Si. On the other hand, when Zr/Si is higher than 30, the Si content is lower than the Zr content. Therefore, the CuZrSi particles cannot be sufficiently formed, and the above-described effects cannot be sufficiently exhibited.

(25) From these points of view, in the embodiment, the ratio Zr/Si of the Zr content (mass %) to a Si content (mass %) is within a range of 2 to 30. In order to reliably suppress a decrease in the electrical conductivity, it is preferable that Zr/Si is set to be 3 or higher. In addition, in order to secure the number of CuZrSi particles to reliably improve the strength, Zr/Si is preferably 25 or lower, and is more preferably 20 or lower.

(26) (Ag, Sn, Al, Ni, Zn, Mg)

(27) Ag, Sn, Al, Ni, Zn, or Mg has an effect of forming a solid solution in the matrix of copper to improve the strength. Accordingly, in order to realize further improvement in the strength, it is preferable that the above elements are appropriately added.

(28) Here, when the total content of one element or two or more elements selected from the group consisting of Ag, Sn, Al, Ni, Zn, and Mg is lower than 0.005 mass %, the above-described effect may not be reliably exhibited. On the other hand, when the total amount of one element or two or more elements selected from the group consisting of Ag, Sn, Al, Ni, Zn, and Mg is higher than 0.1 mass %, the electrical conductivity may significantly decrease.

(29) From these points of view, in order to realize further improvement in the strength through the addition of Ag, Sn, Al, Ni, Zn, or Mg, it is preferable that the total content of one element or two or more elements selected from the group consisting of Ag, Sn, Al, Ni, Zn, and Mg is within a range of 0.005 mass % to 0.1 mass %.

(30) (Ti, Co, Cr)

(31) Ti, Co, or Cr constitute precipitate particles and has an effect of significantly improving the strength while maintaining the electrical conductivity. Accordingly, in order to realize further improvement in the strength, it is preferable that the above elements are appropriately added.

(32) Here, when the total amount of one element or two or more elements selected from the group consisting of Ti, Co, and Cr is lower than 0.005 mass %, the above-described effect may not be reliably exhibited. On the other hand, when the total content of one element or two or more elements selected from the group consisting of Ti, Co, and Cr is higher than 0.1 mass %, the electrical conductivity may decrease.

(33) From these points of view, in order to realize further improvement in the strength through the addition of Ti, Co, or Cr, it is preferable that the total content of one element or two or more elements selected from the group consisting of Ti, Co, and Cr is within a range of 0.005 mass % to 0.1 mass %.

(34) (P, Ca, Te, B)

(35) P, Ca, Te, or B constitutes relatively coarse particles through crystallization and segregation during melting and casting and has an effect of significantly improving the shearing performance. Accordingly, in order to further improve the shearing performance, it is preferable that the above elements are appropriately added.

(36) Here, when the total content of one element or two or more elements selected from the group consisting of P, Ca, Te, and B is lower than 0.005 mass %, the above-described effect may not be reliably exhibited. On the other hand, when the total content of one element or two or more elements selected from the group consisting of P, Ca, Te, and B is higher than 0.1 mass %, the electrical conductivity may decrease.

(37) From these points of view, in order to realize further improvement in the shearing performance through the addition of P, Ca, Te, or B, it is preferable that the total content of one element or two or more elements selected from the group consisting of P, Ca, Te, and B is within a range of 0.005 mass % to 0.1 mass %.

(38) (Unavoidable Impurities)

(39) Examples of the unavoidable impurities other than the above-described elements include Fe, Mn, Sr, Ba, Sc, Y, Hf, V, Nb, Ta, Mo, W, Re, Ru, Os, Se, Rh, Ir, Pd, Pt, Au, Cd, Ga, In, Li, Ge, As, Sb, Tl, Pb, C, Be, N, H, Hg, Tc, Na, K, Rb, Cs, O, S, Po, Bi, and lanthanoid elements. It is preferable that the total amount of these unavoidable impurities is preferably 0.3 mass % or lower.

(40) (CuZrSi Particles)

(41) When Zr and Si are added to Cu, CuZrSi particles containing Cu, Zr, and Si are present. In the embodiment, as described above, as the CuZrSi particles, relatively coarse particles having a particle size of 1 m to 50 m and fine particles having a particle size of 1 nm to 500 nm are present.

(42) Here, it is presumed that the coarse CuZrSi particles having a particle size of 1 m to 50 m are crystallized or segregated during melting and casting. In addition, it is presumed that the fine CuZrSi particles having a particle size of 1 nm to 500 nm are precipitated during a subsequent heat treatment or the like.

(43) The coarse CuZrSi particles having a particle size of 1 m to 50 m do not contribute to the improvement of the strength but can significantly improve the shearing performance by functioning as a fracture origin when shearing represented by press punching is performed.

(44) On the other hand, the fine CuZrSi particles having a particle size of 1 nm to 500 nm contribute to the improvement of the strength and can improve the yield strength while maintaining high electrical conductivity. Alternatively, the electrical conductivity can be further improved while maintaining high yield strength. In addition, the Vickers hardness can be improved.

(45) (Electrical Conductivity: 80% IACS or Higher)

(46) When Zr and Si form a solid solution in the matrix of Cu, the electrical conductivity significantly decreases. Therefore, in the embodiment, the electrical conductivity is defined to be 80% IACS or higher. Thus, the above-described CuZrSi particles are sufficiently present, and the strength and the shearing performance can be reliably improved.

(47) In order to reliably exhibit the above-described effects, the electrical conductivity is preferably 85% IACS or higher, and is more preferably 88% IACS or higher. In addition, the upper limit value of the electrical conductivity of the copper alloy for electric and electronic devices according to the embodiment is not particularly limited but may be lower than 100% IACS.

(48) Next, a method of manufacturing the copper alloy for electric and electronic devices according to the embodiment having the above-described configuration will be described with reference to a flow chart shown in FIG. 1.

(49) (Melting and Casting Step S01)

(50) First, Zr and Si are added to molten copper obtained by melting a copper raw material to adjust the components. As a result, molten copper alloy is prepared. During the addition of Zr and Si, for example, elemental Zr, elemental Si, a CuZr master alloy, or a CuSi master alloy can be used. In addition, a raw material containing Zr and Si may be melted together with a copper raw material. In addition, a recycled material or a scrap material of the alloy may be used. When an element other than Zr and Si (for example, Ag, Sn, Al, Ni, Zn, Mg, Ti, Co, Cr, P, Ca, Te, or B) is added, various raw materials can be used as described above.

(51) It is preferable that the molten copper is a so-called 4NCu having a purity of 99.99 mass % or higher. In addition, during the preparation of the molten copper alloy, it is preferable that a vacuum furnace or a furnace in an atmosphere such as an inert gas atmosphere, or a reducing atmosphere is used in order to suppress, for example, oxidation of Zr and Si.

(52) The molten copper alloy whose components are adjusted is poured into a casting mold to prepare an ingot. In consideration of mass production, it is preferable that a continuous casting method or a semi-continuous casting method is used.

(53) (Heat Treatment Step S02)

(54) Next, a heat treatment is performed for the homogenization and solutionization of the obtained ingot. By performing a heat treatment of heating the ingot at 800 C. to 1080 C., Zr and Si are homogeneously dispersed in the ingot and form a solid solution in the matrix. It is preferable that the heat treatment step S02 is performed in a non-oxidizing or reducing atmosphere.

(55) A cooling method after heating is not particularly limited, but a method such as water quenching in which the cooling rate is 200 C./min or higher is preferably adopted.

(56) (Hot Working Step S03)

(57) Next, hot working is performed for the optimization of rough processing and the homogenization of the structure. A working method is not particularly limited. However, when it is desired that the final shape is a sheet or a strip, rolling is preferably adopted. When it is desired that the final shape is a wire or a rod, extrusion or groove rolling is preferably adopted. When it is desired that the final shape is a bulk shape, forging or pressing is preferably adopted. The temperature during the hot working is not particularly limited but is preferably within a range of 500 C. to 1050 C.

(58) A cooling method after the hot working is not particularly limited, but a method such as water quenching in which the cooling rate is 200 C./min or higher is preferably adopted.

(59) (Intermediate Working Step S04/Intermediate Heat Treatment Step S05)

(60) In addition, after the hot working, intermediate working and an intermediate heat treatment may be performed for softening in order to strictly perform solutionization or to recrystallize the structure, or to improve workability. Temperature conditions in the intermediate working step S04 are not particularly limited but are preferably within a range of 200 C. to 200 C. in which cold working is performed. In addition, a working ratio in the intermediate working step S04 is appropriately selected so as to obtain a shape close to the final shape. In order to reduce the number of times of the intermediate heat treatment step S05 until the final shape is obtained, the working ratio is preferably 20% or higher. In addition, the working ratio is more preferably 30% or higher. A plastic working method is not particularly limited. For example, rolling, wire drawing, extrusion, groove rolling, forging, or pressing can be adopted.

(61) A heat treatment method in the intermediate heat treatment step S05 is not particularly limited, but it is preferable that the heat treatment is performed in a non-oxidizing atmosphere or a reducing atmosphere under a condition of 500 C. to 1050 C. The intermediate working step S04 and the intermediate heat treatment step S05 may be repeated.

(62) (Finishing Step S06)

(63) Next, the material which has undergone the above-described steps is optionally cut, and a surface thereof is optionally polished to remove an oxide film or the like formed on the surface. Cold working is performed at a predetermined working ratio. Temperature conditions in the finishing step S06 are not particularly limited but are preferably within a range of 200 C. to 200 C. In addition, a working ratio is appropriately selected so as to obtain a shape close to the final shape. In order to improve the strength through work hardening, the working ratio is preferably 30% or higher. In order to realize further improvement in the strength, the working ratio is preferably 50% or higher. A plastic working method is not particularly limited. However, when it is desired that the final shape is a sheet or a strip, rolling is preferably adopted. When it is desired that the final shape is a wire or a rod, extrusion or groove rolling is preferably adopted. When it is desired that the final shape is a bulk shape, forging or pressing is preferably adopted.

(64) (Aging Heat Treatment Step S07)

(65) Next, an aging heat treatment is performed on the finished material obtained in the finishing step S06 in order to improve the strength and the electrical conductivity. In the aging heat treatment step S07, fine CuZrSi particles having a particle size of 1 nm to 500 nm are precipitated.

(66) Here, a heat treatment temperature is not particularly limited but is preferably within a range of 250 C. to 600 C. such that CuZrSi particles having the optimum size are uniformly dispersed and precipitated. Since the precipitation state can be recognized based on the electrical conductivity, it is preferable that heat treatment conditions (temperature, time) are appropriately set so as to obtain a predetermined electrical conductivity.

(67) Here, the finishing step S06 and the aging heat treatment step S07 described above may be repeated. In addition, after the aging heat treatment step S07, cold working may be performed at a working ratio of 1% to 70% in order to correct the shape and to improve the strength. Further, a heat treatment may be performed in order to perform thermal refining or to remove residual strain. A cooling method after the heat treatment is not particularly limited, but a method such as water quenching in which the cooling rate is 200 C./min or higher is preferably adopted.

(68) Through the above-describes steps, the copper alloy for electronic and electric devices having the CuZrSi particles is prepared. In the copper alloy for electric and electronic devices, the 0.2% yield strength is 300 MPa or higher, and the Vickers hardness is 100 HV or higher.

(69) In addition, when rolling is used as the working method in the finishing step S06, a copper alloy sheet (strip) for electric and electronic devices having a thickness of about 0.05 mm to 1.0 mm can be obtained. This sheet can be used for a component for electric and electronic devices without any change. However, a single surface or both surfaces of the sheet may be plated with Sn or Ag to form a film having a thickness of about 0.1 m to 10 m, thereby obtaining a plated copper alloy strip.

(70) Further, for example, a component for electric and electronic devices such as a terminal (for example, a connector), a relay, a lead frame, or a bus bar can be formed by punching or bending the copper alloy for electronic and electric devices (copper alloy sheet for electric and electronic devices) according to the embodiment as a raw material.

(71) In the copper alloy for electronic and electric devices according to the embodiment having the above-described configuration, the Zr content is 0.01 mass % or higher and lower than 0.11 mass %, the Si content is 0.002 mass % or higher and lower than 0.03 mass %, and the ratio Zr/Si of the Zr content (mass %) to the Si content (mass %) is within a range of 2 to 30. Therefore, the above-described CuZrSi particles are formed and are dispersed in the matrix of copper. As a result, the yield strength can be improved while maintaining the electrical conductivity, or the electrical conductivity can be improved while maintaining the yield strength. In addition, the Vickers hardness can be improved.

(72) Here, the copper alloy for electric and electronic devices according to the embodiment includes the fine CuZrSi particles having a particle size of 1 nm to 500 nm. Therefore, the yield strength can be improved while maintaining high electrical conductivity.

(73) Alternatively, the electrical conductivity can be further improved while maintaining high yield strength. In addition, the Vickers hardness can be improved.

(74) Further, the copper alloy for electric and electronic devices according to the embodiment includes the coarse CuZrSi particles having a particle size of 1 m to 50 m. Therefore, the shearing performance can be significantly improved by the coarse CuZrSi particles functioning as a fracture origin during shearing.

(75) In addition, in the copper alloy for electric and electronic devices according to the embodiment, the electrical conductivity is 80% IACS or higher. Therefore, Zr and Si do not form a solid solution in the matrix of copper, and the CuZrSi particles are sufficiently dispersed in the matrix. As a result, the strength can be reliably improved. In addition, the copper alloy for electric and electronic devices according to the embodiment can be used as a material of a component for electric and electronic devices in which particularly high electrical conductivity is required.

(76) Here, when the copper alloy for electric and electronic devices according to the embodiment further includes 0.005 mass % to 0.1 mass % in total of one element or two or more elements selected from the group consisting of Ag, Sn, Al, Ni, Zn, and Mg, the yield strength can be further improved by the above elements forming a solid solution in the matrix of copper. That is, the strength can be improved through solid solution strengthening.

(77) In addition, when the copper alloy for electric and electronic devices according to the embodiment further includes 0.005 mass % to 0.1 mass % in total of one element or two or more elements selected from the group consisting of Ti, Co, and Cr, these elements are precipitated alone or as a compound. As a result, the yield strength can be further improved without a decrease in the electrical conductivity. That is, the strength can be improved through precipitation strengthening.

(78) Further, when the copper alloy for electric and electronic devices according to the embodiment further includes 0.005 mass % to 0.1 mass % in total of one element or two or more elements selected from the group consisting of P, Ca, Te, and B, relatively coarse particles are formed by the crystallization and segregation of the above elements during melting and casting. As a result, the shearing performance can be significantly improved by the coarse particles functioning as a fracture origin during shearing.

(79) Further, the copper alloy for electric and electronic devices according to the embodiment has mechanical characteristics in which the 0.2% yield strength is 300 MPa or higher. Therefore, the copper alloy for electric and electronic devices according to the embodiment is suitable for a component in which particularly high strength is required, for example, for a movable contact of an electromagnetic relay or a spring portion of a terminal.

(80) The copper alloy sheet for electric and electronic devices according to the embodiment includes a rolled material of the above-described copper alloy for electric and electronic devices. Therefore, the copper alloy for electric and electronic devices according to the embodiment has superior stress relaxation resistance and can be suitably used for a connector, other terminals, a movable contact of an electromagnetic relay, a lead frame, or a bus bar. In addition, according to the intended use, a Sn plating film or an Ag plating film may be formed on the surface of the copper alloy.

(81) The component for electric and electronic devices, the terminal, and the bus bar according to the embodiment includes the above-described copper alloy for electric and electronic devices according to the embodiment. Therefore, the dimensional accuracy is superior, and superior characteristics can be exhibited even when the size and thickness are reduced.

(82) Hereinabove, the copper alloy for electronic and electric devices according to the embodiment of the present invention has been described. However, the present invention is not limited to the embodiment and can be modified in various ways within a scope not departing from the technical idea of the present invention.

(83) For example, in the above-described embodiment, an example of the method of manufacturing the copper alloy for electronic and electric devices has been described. However, the manufacturing method is not limited to the embodiment, and may be appropriately selected from existing manufacturing methods.

EXAMPLES

(84) Hereinafter, the results of an experiment which was performed in order to verify the effects of the present invention will be described.

(85) A copper raw material formed of oxygen-free copper (ASTM F68-Class1) having a purity of 99.99 mass % or higher was prepared. This copper raw material was charged into a high-purity graphite crucible and was melted using high-frequency induction heating in an atmosphere furnace having an Ar gas atmosphere. The component composition in the obtained molten copper was adjusted as shown in Tables 1 and 2 by adding various additional elements. Next, the molten copper was poured into a water-cooling copper mold to prepare an ingot. The size of the ingot was thickness: about 20 mm, width: about 20 mm, and length: about 100 mm to 120 mm.

(86) A heat treatment step was performed on the obtained ingot in which the ingot was heated in an Ar gas atmosphere for 4 hours under temperature conditions shown in Tables 3 and 4 for homogenization and solutionization. Next, water quenching was performed. The heat-treated ingot was cut, and a surface thereof was polished to remove an oxide film.

(87) Next, hot rolling was performed at a working ratio and a temperature shown in Tables 3 and 4, water quenching was performed, and cold rolling as a finishing step was performed under conditions shown in Tables 3 and 4. As a result, a strip having a thickness of about 0.5 mm was prepared.

(88) An aging heat treatment was performed on the obtained strip at a temperature shown in Tables 3 and 4 until the electrical conductivity shown in Tables 5 and 6 was obtained. As a result, a strip for evaluating characteristics thereof was prepared.

(89) (Evaluation of Workability)

(90) In order to evaluate workability, whether or not edge cracking (cold rolling cracking) occurred during the above-described finishing step (during cold rolling) was observed. A strip where edge cracking did not occur in all the regions or substantially all the regions was evaluated as A, a strip where a small edge crack having a length of less than 1 mm was formed was evaluated as B, a strip where an edge crack having a length of 1 mm or more and less than 3 mm was formed was evaluated as C, and a strip where a large edge crack having a length of more than 3 mm was formed was evaluated as D. It was determined that C in which the length of the edge crack was 1 mm or more and less than 3 mm had no problems in practice.

(91) The length of the edge crack refers to the length of an edge crack formed from an end to the center of the rolled material in a width direction thereof. The evaluation results are shown in Tables 5 and 6.

(92) (Particle Observation)

(93) In order to verify CuZrSi particles containing Cu, Zr, and Si, particles were observed using a transmission electron microscope (TEM: JEM-2010F, manufactured by JEOL Ltd.) and were analyzed by energy dispersive X-ray spectroscopy (EDX).

(94) First, as shown in FIG. 2, the particles were observed using a TEM at 20,000 times (observation visual field: 210.sup.7 nm.sup.2). As shown in FIG. 3A, the observed particles were observed at 100,000 times (observation visual field: 710.sup.5 nm.sup.2). In addition, particles having a particle size of less than 10 nm were observed at 500,000 times (observation visual field: 310.sup.4 nm.sup.2).

(95) In addition, the composition of the observed particles was analyzed by energy dispersive X-ray spectroscopy (EDX), and it was verified that these particles were CuZrSi particles. An example of the EDX analysis results is shown in FIG. 3B.

(96) As the particle size of the CuZrSi particles, an average value of a long diameter (the length of the longest line in a particle in non-contact with a grain boundary) and a short diameter (the length of the longest line in a direction perpendicular to the long diameter in non-contact with a grain boundary) was set.

(97) A case where the CuZrSi particles having a particle size of 1 nm to 500 nm were observed by the structure observation was evaluated as A, and a case where the CuZrSi particles having a particle size of 1 nm to 500 nm were not observed by the structure observation was evaluated as D. The evaluation results are shown in Tables 5 and 6.

(98) (Electrical Conductivity)

(99) A specimen having a width of 10 mm and a length of 60 mm was collected from the strip for evaluating characteristics thereof, and the electrical resistance thereof was obtained using a four-terminal method. In addition, the dimensions of the specimen were measured using a micrometer to calculate the volume of the specimen. The electrical conductivity was calculated based on the measured electrical resistance value and the volume. The specimen was collected from the strip for evaluating characteristics thereof using a method in which a longitudinal direction of the specimen was perpendicular to a rolling direction of the strip for evaluating characteristics thereof. The measurement results are shown in Tables 5 and 6.

(100) (Mechanical Characteristics)

(101) 13B specimen defined in JIS Z 2241 (ISO 6892-1: 2009, Metallic materials-Tensile testing-Part 1: Method of test at room temperature (MOD)) was collected from the strip for evaluating characteristics thereof, and the 0.2% yield strength and tensile strength thereof were measured using an offset method. The specimen was collected from the strip for evaluating characteristics thereof using a method in which a tensile direction of the tensile test was perpendicular to a rolling direction of the strip for evaluating characteristics thereof.

(102) In addition, the Young's modulus E was obtained by attaching a strain gauge to the above-described specimen to obtain a gradient of a load-elongation curve. The evaluation results are shown in Tables 5 and 6.

(103) (Vickers Hardness)

(104) The Vickers hardness was measured at a test load of 0.98 N in a micro-Vickers hardness test method defined in JIS Z 2244 (ISO 6507-4). The evaluation results are shown in Tables 5 and 6.

(105) TABLE-US-00001 TABLE 1 Component Composition (mass %) Zr Si Zr/Si Other Elements Cu Ex- 1 0.107 0.023 4.7 Balance ample 2 0.107 0.023 4.7 Balance 3 0.073 0.021 3.5 Balance 4 0.073 0.021 3.5 Balance 5 0.051 0.022 2.3 Balance 6 0.051 0.022 2.3 Balance 7 0.097 0.016 6.1 Balance 8 0.097 0.016 6.1 Balance 9 0.057 0.009 6.3 Balance 10 0.057 0.009 6.3 Balance 11 0.018 0.009 2.0 Balance 12 0.018 0.009 2.0 Balance 13 0.085 0.003 28.3 Balance 14 0.085 0.003 28.3 Balance 15 0.050 0.003 16.7 Balance 16 0.050 0.003 16.7 Balance 17 0.034 0.004 8.5 Balance 18 0.034 0.004 8.5 Balance 19 0.069 0.023 3.0 Ag: 0.034 Zn: 0.036 Balance 20 0.071 0.023 3.1 Ag: 0.030 Zn: 0.025 Co: Balance 0.01 21 0.086 0.029 3.0 Sn: 0.039 Balance 22 0.083 0.028 3.0 Sn: 0.042 B: 0.005 Balance 23 0.073 0.020 3.7 Al: 0.006 Balance 24 0.071 0.019 3.7 Al: 0.008 Ti: 0.008 Balance

(106) TABLE-US-00002 TABLE 2 Component Composition (mass %) Zr Si Zr/Si Other Elements Cu Ex- 25 0.073 0.021 3.5 Ni: 0.043 Balance ample 26 0.075 0.020 3.8 Ni: 0.022 Cr: Balance 0.02 27 0.063 0.022 2.9 Mg: 0.046 Balance 28 0.066 0.024 2.8 Mg: 0.040 Te: Balance 0.007 29 0.059 0.021 2.8 Sn: 0.065 Mg: Balance 0.027 30 0.059 0.024 2.5 Sn: 0.048 Mg: Co: Balance 0.011 0.008 31 0.053 0.025 2.1 Ti: 0.008 Balance 32 0.050 0.021 2.4 Ti: 0.006 Ca: Balance 0.005 33 0.074 0.020 3.7 Co: 0.028 Balance 34 0.072 0.021 3.4 Co: 0.020 Mg: Te: Balance 0.017 0.005 35 0.096 0.010 9.6 Cr: 0.075 Balance 36 0.092 0.009 10.2 Cr: 0.060 Zn: Ca: Balance 0.007 0.010 37 0.076 0.019 4.0 P: 0.006 Balance 38 0.078 0.021 3.7 P: 0.006 Al: Balance 0.007 39 0.065 0.015 4.3 Ca: 0.006 Balance 40 0.064 0.015 4.3 Ca: 0.006 Ag: Balance 0.010 41 0.070 0.016 4.4 Te: 0.015 Balance 42 0.072 0.018 4.0 Te: 0.010 Zn: Balance 0.007 43 0.091 0.012 7.6 B: 0.005 Balance 44 0.093 0.012 7.8 B: 0.007 Al: Balance 0.010 Com- 1 0.187 0.007 26.7 Balance parative 2 0.003 0.001 3.0 Balance Ex- 3 0.055 0.041 1.3 Balance ample

(107) TABLE-US-00003 TABLE 3 Heat Treatment Hot Working Step Finishing Step Aging Heat Step Rolling Start End Rolling Treatment Step Temperature Reduction Temperature Temperature Reduction Temperature C. % C. C. % C. Example 1 960 60 900 700 94 400 2 960 60 900 700 94 450 3 960 60 900 700 94 400 4 960 60 900 700 94 450 5 960 60 900 700 94 400 6 960 60 900 700 94 450 7 960 60 900 700 94 400 8 960 60 900 700 94 450 9 960 60 900 700 94 400 10 960 60 900 700 94 450 11 960 60 900 700 94 400 12 960 60 900 700 94 450 13 960 60 900 700 94 400 14 960 60 900 700 94 450 15 960 60 900 700 94 400 16 960 60 900 700 94 450 17 960 60 900 700 94 400 18 960 60 900 700 94 450 19 960 60 900 700 94 400 20 960 60 900 700 94 450 21 960 60 900 700 94 400 22 960 60 900 700 94 450 23 960 60 900 700 94 400 24 960 60 900 700 94 450

(108) TABLE-US-00004 TABLE 4 Heat Finishing Aging Heat Treatment Hot Working Step Step Treatment Step Rolling Start End Rolling Step Temperature Reduction Temperature Temperature Reduction Temperature C. % C. C. % C. Example 25 960 60 900 700 94 400 26 960 60 900 700 94 450 27 960 60 900 700 94 400 28 960 60 900 700 94 450 29 960 60 900 700 94 400 30 960 60 900 700 94 450 31 960 60 900 700 94 400 32 960 60 900 700 94 450 33 960 60 900 700 94 400 34 960 60 900 700 94 450 35 960 60 900 700 94 400 36 960 60 900 700 94 450 37 960 60 900 700 94 400 38 960 60 900 700 94 450 39 960 60 900 700 94 400 40 960 60 900 700 94 450 41 960 60 900 700 94 400 42 960 60 900 700 94 450 43 960 60 900 700 94 400 44 960 60 900 700 94 450 Comparative 1 960 60 900 700 94 Example 2 960 60 900 700 94 350 3 960 60 900 700 94 400

(109) TABLE-US-00005 TABLE 5 Electrical 0.2% Yield Vickers Cold Rolling CuZrSi Particles having Conductivity Strength Hardness Cracking Size of 1 nm to 500 nm % IACS MPa HV Example 1 C A 82.9 525 177 2 C A 84.5 500 173 3 A A 85.8 479 162 4 A A 89.2 446 155 5 A A 87.6 456 153 6 A A 91.4 420 145 7 C A 83.9 514 173 8 C A 85.1 498 174 9 A A 89.8 446 149 10 A A 93.8 405 140 11 A A 91.3 425 143 12 A A 92.9 400 138 13 A A 88.6 481 161 14 A A 90.0 448 154 15 A A 91.0 444 148 16 A A 92.5 425 147 17 A A 91.3 437 146 18 A A 94.3 311 102 19 A A 84.1 500 168 20 A A 87.3 465 160 21 B A 86.8 503 170 22 B A 91.1 475 162 23 A A 85.2 479 162 24 A A 87.9 460 159

(110) TABLE-US-00006 TABLE 6 CuZrSi Particles Electrical 0.2% Yield Vickers Cold Rolling having Size of 1 nm to Conductivity Strength Hardness Cracking 500 nm % IACS MPa HV Example 25 A A 83.9 489 165 26 A A 87.3 461 160 27 A A 86.3 481 162 28 A A 89.5 450 157 29 A A 86.3 493 165 30 A A 90.3 473 164 31 A A 86.6 482 162 32 A A 90.2 455 158 33 A A 84.3 495 165 34 A A 87.7 458 158 35 C A 81.5 526 179 36 C A 84.0 504 174 37 B A 90.0 470 157 38 B A 92.1 448 155 39 C A 88.8 469 157 40 C A 92.3 440 153 41 C A 87.2 472 157 42 C A 90.0 442 152 43 C A 89.8 465 157 44 C A 93.0 432 150 Comparative 1 D Example 2 A D 97.5 218 96 3 A A 75.6 475 153

(111) In Comparative Example 1 in which the Zr content is higher the range of the present invention, a large edge crack was formed during finishing (cold rolling). Therefore, the subsequent step was not evaluated.

(112) In Comparative Example 2 in which the Zr content is lower than the range of the present invention, the CuZrSi particles having a particle size of 1 nm to 500 nm were not observed, the 0.2% yield strength was lower than 218 MPa, and the Vickers hardness was insufficient. Here, the reason why the electrical conductivity was high in Comparative Example 2 although the CuZrSi particles were not present is as follows. Since the addition amounts of Zr and Si were excessively small, Zr and Si were not precipitated, and the amount of a solid solution in copper is small.

(113) In Comparative Example 3 in which the ratio Zr/Si of the Zr content (mass %) to the Si content (mass %) is lower than the range of the present invention, the electrical conductivity significantly decreased. Here, the reason why the electrical conductivity was low in Comparative Example 3 although the CuZrSi particles were present is as follows. Although the CuZrSi particles were precipitated, an excess amount of Si was added and thus formed a solid solution in copper.

(114) On the other hand, in Examples 1 to 44, a large edge crack having a length of 3 mm or more was not formed during finishing (cold rolling). In addition, in all of the Examples 1 to 44, the CuZrSi particles having a particle size of 1 nm to 500 nm were observed, and the electrical conductivity and the yield strength were high. Further, the Vickers hardness was high.

(115) It was verified from the above results that, according to Examples, a copper alloy for electric and electronic devices can be provided which has high electrical conductivity, high yield strength, and high Vickers hardness and is suitable for a component for electric and electronic devices.