JP7351171B2 - Copper alloys for electronic and electrical equipment, copper alloy sheets and strips for electronic and electrical equipment, parts for electronic and electrical equipment, terminals, and bus bars - Google Patents

Description

The present invention relates to a copper alloy for electronic and electrical equipment suitable for parts for electronic and electrical equipment such as terminals such as connectors and press-fits, and bus bars, and a copper alloy plate for electronic and electrical equipment made of this copper alloy for electronic and electrical equipment. It relates to strips, parts for electronic and electrical equipment, terminals, and bus bars.

BACKGROUND ART Conventionally, highly conductive copper or copper alloy has been used for parts for electronic and electrical equipment such as terminals such as connectors and press-fits, and bus bars.
With the increase in currents in electronic devices and electrical devices, large-sized electronic and electrical equipment components used in these devices are required to reduce current density and spread heat due to Joule heating. The structure is being made thicker and thicker. For this reason, materials constituting parts for electronic and electrical equipment are required to have high electrical conductivity and punching workability during press working. In addition, stress relaxation resistance is also required for connector terminals and the like used in high-temperature environments such as the engine room of automobiles.

Here, for example, Patent Document 1 proposes a Cu--Sn alloy as a material to be used in terminals such as connectors and press-fits, and parts for electronic and electrical equipment such as bus bars.

JP2016-191088A

Here, in the Cu-Sn alloy described in Patent Document 1, the ratio (r) of the half width to the plate thickness determined from the displacement-load curve in the shear test is 0.2≦r≦0.7. By using a certain copper alloy plate, a press fracture surface is formed early on the copper alloy plate sandwiched between the punch and die during press processing, resulting in a press fracture surface with a large proportion of the fracture surface. It is said that the occurrence of burrs can be effectively suppressed, thereby greatly improving press punching properties.

However, in the above-mentioned method, when the wall thickness increases to 2.0 mm or more, for example, the burr height that occurs during punching increases, and the punching workability during press working decreases (Patent Document 1) (See paragraph number 0032).

The present invention has been made in view of the above-mentioned circumstances, and includes a copper alloy for electronic and electrical equipment, and a copper alloy for electronic and electrical equipment, which has excellent conductivity, strength, stress relaxation resistance, and punching workability. The object of the present invention is to provide a plate and strip material, and parts, terminals, and bus bars for electronic and electrical equipment made of the copper alloy plate and strip material for electronic and electrical equipment.

In order to solve this problem, the inventors of the present invention conducted extensive studies and found that by setting the content of Sn contained in the alloy within a predetermined range, the electrical conductivity, strength, and stress relaxation properties can be improved. We obtained the knowledge that this is possible.
In addition, as a result of analyzing the parent phase using the EBSD method using the plane perpendicular to the rolling width direction as the observation plane in Cu-Sn alloys, the ratio of special grain boundaries and random grain boundaries that constitute the grain boundary triple points was found. It has been found that by specifying , cracks can easily propagate along grain boundaries during press working, and it is also possible to improve punching workability during press working.

In order to solve this problem, the copper alloy for electronic and electrical equipment of the present invention contains one or more elements selected from Sn, Ni, and Zn in a total amount of 0.05 mass% or more and less than 0.4 mass%. with the remainder consisting of Cu and unavoidable impurities, and using the plane including the rolling direction and rolling direction as the observation plane, the matrix was measured using the EBSD method over a measurement area of 10,000 μm ² or more, with a measurement interval of 0.25 μm. Excluding the measurement points where the CI value is 0.1 or less in the step, analyze the orientation difference of each grain, and define the grain boundaries between measurement points where the orientation difference between adjacent measurement points is 15° or more. , the average grain ^size is determined by Area Fraction, and the grain size is measured at a measurement interval of 1/10 or less of the average grain size. With a measurement area of , when the corresponding grain boundaries of Σ29 and below are treated as special grain boundaries, and the other grain boundaries are treated as random grain boundaries, in the grain boundary triple points analyzed from OIM, all three grain boundaries constituting the grain boundary triple points are special grain boundaries. The ratio of J3 to all grain boundary triple points is NF _J3 , and the ratio of J2 to all grain boundary triple points where two grain boundaries constituting the grain boundary triple point are special grain boundaries and one is a random grain boundary is NF J3. When set to NF _J2 ,
It is characterized in that 0.23 <(NF _J2 /(1-NF _J3 )) ^0.5 ≦0.45 holds true.

Note that the EBSD method refers to the electron beam reflection diffraction method (Electron Backscatter Diffraction Patterns: EBSD) using a scanning electron microscope equipped with a backscattered electron diffraction image system, and OIM refers to the crystal orientation determination using the measurement data by EBSD. This is data analysis software (Orientation Imaging Microscopy: OIM) for analyzing. Furthermore, the CI value is a confidence index, which is a numerical value that indicates the reliability of crystal orientation determination when analyzed using the analysis software OIM Analysis (Ver. 7.3.1) of the EBSD device. (For example, "EBSD Reader: How to Use OIM (Revised 3rd Edition)" by Seiichi Suzuki, September 2009, published by TSL Solutions Co., Ltd.).
Here, if the structure at the measurement point measured by the EBSD method and analyzed by OIM is a processed structure, the crystal pattern is not clear, so the reliability of crystal orientation determination becomes low, and the CI value becomes low. In particular, when the CI value is 0.1 or less, the tissue at that measurement point is determined to be a processed tissue.

In addition, special grain boundaries are defined based on crystallographic CSL theory (Kronberg et al: Trans.Met.Soc.AIME, 185, 501 (1949)), and correspond to a correspondence that belongs to 3≦Σ≦29. It is a grain boundary, and the specific corresponding site lattice orientation defect Dq in the corresponding grain boundary is Dq≦15°/Σ ^1/2 (D.G. Brandon: Acta.Metallurgica.Vol.14, p.1479, (1966)).
On the other hand, random grain boundaries are grain boundaries other than special grain boundaries that have a corresponding orientation relationship with a Σ value of 29 or less and satisfy Dq≦15°/Σ1/2.

The grain boundary triple points are J0, where all three grain boundaries are random grain boundaries, J1, where one grain boundary is a special grain boundary and two grain boundaries are random grain boundaries, and J1, where two grain boundaries are random grain boundaries. There are four types: J2, where one is a special grain boundary and one is a random grain boundary, and J3, where all three grain boundaries are special grain boundaries.
Therefore, the ratio NF _J3 of J3, in which all three grain boundaries constituting the grain boundary triple point are special grain boundaries, to all the grain boundary triple points is ΣJ0 for the total number of J0, ΣJ1 for the total number of J1, and ΣJ2 for the total number of J2. , J3 is defined as ΣJ3, NF _J3 =ΣJ3/(ΣJ0+ΣJ1+ΣJ2+ΣJ3).
In addition, two grain boundaries constituting the grain boundary triple point are special grain boundaries, and one is a random grain boundary. The ratio NF _J2 of J2 to all grain boundary triple points is defined as NF _J2 = ΣJ2/(ΣJ0 + ΣJ1 + ΣJ2 + ΣJ3) be done.

According to the copper alloy for electronic/electrical equipment having the above-mentioned configuration, it contains one or more elements selected from Sn, Ni, and Zn in a total amount of 0.05 mass% or more and less than 0.4 mass%. Therefore, it is possible to improve the strength and stress relaxation properties without significantly reducing the electrical conductivity.

In addition, using the plane including the rolling direction and the rolling direction as the observation surface, the matrix was measured using the EBSD method over a measurement area of 10,000 μm ² or more in steps with a measurement interval of 1/10 or less of the average grain size, and the data was analyzed. The measurement points analyzed by soft OIM with a CI value of 0.1 or less are analyzed, and the grain boundaries are defined as grain boundaries between the measurement points where the orientation difference between adjacent measurements is 15° or more, and the corresponding grain boundaries are Σ29 or less. is a special grain boundary, and the others are random grain boundaries. At the grain boundary triple point analyzed from OIM, all three grain boundaries that make up the grain boundary triple point are special grain boundaries. When the ratio to the triple point is NF _J3 , and the ratio of J2 to the total grain boundary triple points, where two grain boundaries constituting the grain boundary triple point are special grain boundaries and one is a random grain boundary, is NF _J2 , Since it satisfies 0.23 <(NF _J2 / (1-NF _J3 )) ^0.5 ≦0.45, cracks tend to grow along the grain boundaries, improving punching workability during press working. becomes possible.

Here, in the copper alloy for electronic/electrical equipment of the present invention, it is preferable that the conductivity is 75% IACS or more.
In this case, the electrical conductivity is sufficiently high and it becomes possible to apply it to applications that require high electrical conductivity.

Furthermore, in the copper alloy for electronic/electrical equipment of the present invention, it is preferable that the 0.2% proof stress is in the range of 200 MPa or more and 500 MPa or less when a tensile test is conducted in a direction parallel to the rolling direction.
In this case, since the 0.2% yield strength when performing a tensile test in the direction parallel to the rolling direction is within the range of 200 MPa or more and 500 MPa or less, coiled Even if it is wound up, it does not become curly, making it easy to handle and achieving high productivity. Therefore, it is particularly suitable as a copper alloy for parts for electronic and electrical equipment such as connectors for large currents and high voltages, press-fit terminals, and bus bars.

Further, in the copper alloy for electronic/electrical equipment of the present invention, it is preferable that the residual stress rate is 70% or more at 150° C. for 500 hours.
In this case, since the residual stress rate is regulated as described above, permanent deformation can be suppressed to a small level even when used in a high temperature environment, and for example, a decrease in contact pressure of connector terminals etc. can be suppressed. be able to. Therefore, it can be applied as a material for parts for electronic devices used in high-temperature environments such as engine rooms.

The copper alloy plate strip material for electronic/electrical equipment of the present invention is made of the above-mentioned copper alloy for electronic/electrical equipment, and is characterized by having a thickness of more than 0.5 mm.
According to the copper alloy sheet material for electronic and electrical equipment having this configuration, since it is composed of the above-mentioned copper alloy for electronic and electrical equipment, it has excellent conductivity, strength, stress relaxation properties, and punching workability. Therefore, it is particularly suitable as a material for parts for electronic and electrical equipment such as thick connectors, press-fit terminals, and bus bars.

Here, in the copper alloy plate strip for electronic/electrical equipment of the present invention, it is preferable to have a Sn plating layer or an Ag plating layer on the surface.
In this case, since it has a Sn plating layer or an Ag plating layer on the surface, it is particularly suitable as a material for parts for electronic and electrical equipment such as terminals such as connectors and press-fits, and bus bars. In the present invention, "Sn plating" includes pure Sn plating or Sn alloy plating, and "Ag plating" includes pure Ag plating or Ag alloy plating.

The electronic/electrical equipment component of the present invention is characterized by being made of the above-mentioned copper alloy plate strip material for electronic/electrical equipment. Note that the electronic/electrical equipment components in the present invention include terminals such as connectors and press-fits, bus bars, and the like.
Since parts for electronic and electrical equipment with this configuration are manufactured using the above-mentioned copper alloy sheet material for electronic and electrical equipment, they cannot be made larger and thicker to accommodate high-current applications. can also exhibit excellent properties.

The terminal of the present invention is characterized in that it is made of the above-mentioned copper alloy plate strip material for electronic and electrical equipment.
Terminals with this configuration are manufactured using the above-mentioned copper alloy sheet material for electronic and electrical equipment, so they maintain excellent characteristics even when made larger and thicker for high-current applications. able to demonstrate.

The bus bar of the present invention is characterized in that it is made of the above-mentioned copper alloy plate strip material for electronic and electrical equipment.
Bus bars with this configuration are manufactured using the above-mentioned copper alloy sheet material for electronic and electrical equipment, so they maintain excellent characteristics even when made larger and thicker for high current applications. able to demonstrate.

According to the present invention, there is provided a copper alloy for electronic/electrical equipment having excellent conductivity, strength, stress relaxation resistance, and punching workability, a copper alloy plate/strip material for electronic/electrical equipment, and a copper alloy for electronic/electrical equipment. It is possible to provide electronic/electrical device parts, terminals, and bus bars made of alloy plate strips.

FIG. 1 is a flow diagram of a method for manufacturing a copper alloy for electronic/electrical equipment according to the present embodiment.

Below, a copper alloy for electronic and electrical equipment, which is one embodiment of the present invention, will be described.
The copper alloy for electronic and electrical equipment according to the present embodiment contains one or more elements selected from Sn, Ni, and Zn in a total amount of 0.05 mass% or more and less than 0.4 mass%, The remainder has a composition consisting of Cu and unavoidable impurities.

In the copper alloy for electronic and electrical equipment, which is an embodiment of the present invention, the parent phase is measured by the EBSD method using a surface perpendicular to the rolling width direction as the observation surface, ^and the average grain Measurements are taken at measurement intervals of 1/10 or less of the diameter, and the data analysis software OIM is used to analyze the measurement points excluding the CI value of 0.1 or less, and calculate the orientation difference between adjacent measurements. When grain boundaries are defined as grain boundaries between measurement points where The ratio of J3, in which all three grain boundaries constituting the important points are special grain boundaries, to the total grain boundary triple points is NF _J3 , and two grain boundaries constituting the grain boundary triple points are special grain boundaries, and one is random. When the ratio of grain boundary J2 to all grain boundary triple points is NF _J2 ,
0.20<(NF _J2 /(1-NF _J3 )) ^0.5 ≦0.45
is assumed to hold true.

Further, in the copper alloy for electronic/electrical equipment according to this embodiment, it is preferable that the conductivity is greater than 75% IACS.
Furthermore, in the copper alloy for electronic and electrical equipment according to the present embodiment, it is preferable that the 0.2% proof stress is in the range of 200 MPa or more and 500 MPa or less when a tensile test is conducted in a direction parallel to the rolling direction. . That is, in this embodiment, the rolled material is a copper alloy for electronic and electrical equipment, and the 0.2% yield strength when a tensile test is performed in the direction parallel to the rolling direction in the final step of rolling is the above-mentioned value. It is stipulated as follows.
Further, in the copper alloy for electronic/electrical equipment according to the present embodiment, it is preferable that the residual stress rate is 70% or more at 150° C. for 500 hours.

Here, the reason for specifying the component composition, crystal structure, and various properties as described above will be explained below.

(Total content of one or more elements selected from Sn, Ni, and Zn: 0.05 mass% or more and less than 0.4 mass%)
Sn, Ni, and Zn are elements that have the effect of improving strength and stress relaxation properties while maintaining electrical conductivity by being dissolved in the parent phase of a copper alloy.
Here, if the total content of one or more elements selected from Sn, Ni, and Zn is less than 0.05 mass%, there is a possibility that the action and effect cannot be achieved sufficiently. . On the other hand, if the total content of one or more elements selected from Sn, Ni, and Zn is 0.4 mass% or more, the electrical conductivity may decrease.
From the above, in this embodiment, the total content of one or more elements selected from Sn, Ni, and Zn is set within the range of 0.05 mass% or more and less than 0.4 mass%. .
In addition, in order to further improve the strength and stress relaxation resistance, the lower limit of the total content of one or more elements selected from Sn, Ni, and Zn is preferably 0.07 mass% or more. , more preferably 0.10 mass% or more. In addition, in order to reliably suppress the decrease in electrical conductivity, it is preferable that the upper limit of the total content of one or more elements selected from Sn, Ni, and Zn is 0.37 mass% or less, More preferably, it is 0.35 mass% or less.

(Unavoidable impurities: 0.1 mass% or less)
Other unavoidable impurities include Ag, B, Ca, Sr, Ba, Sc, Y, rare earth elements, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru. , Os, Co, Se, Te, Rh, Ir, Pd, Pt, Au, Cd, Hg, Al, Ga, In, Ge, Mg, As, Sb, Tl, Pb, Bi, Be, N, C, Si , Li, H, O, S, P, etc. Since these unavoidable impurities have the effect of lowering the electrical conductivity, the total amount is set to 0.1 mass% or less.
Further, since Si, Cr, Ti, Zr, Fe, and Co significantly reduce the electrical conductivity and deteriorate bending workability due to the formation of inclusions, the total amount of these elements is preferably less than 500 mass ppm.

(Ratio of grain boundary triple points)
The punching workability during press working is better as the burr height at break is smaller. Here, as the thickness of the material to be pressed increases, the burr height tends to increase relatively.
In order to reduce the burr height during press working, fractures should occur quickly along the grain boundaries during press working. As the network of random grain boundaries becomes longer, fractures along the grain boundaries are more likely to occur. In order to increase the network length of random grain boundaries, all of the three grain boundaries constituting the grain boundary triple point must be J3, which is a special grain boundary expressed by Σ29 or less, or two of the three must be special grain boundaries. It is important to control the proportion of J2.

Therefore, in this embodiment, using the plane orthogonal to the rolling width direction as the observation plane, the matrix is measured using the EBSD method to measure an area of 10,000 μm ² or more at a measurement interval of 1/10 or less of the average grain size. Measurement is performed in steps, excluding measurement points with a CI value of 0.1 or less analyzed using the data analysis software OIM, and identifying grain boundaries between measurement points where the orientation difference between adjacent measurements is 15° or more. When the corresponding grain boundaries of Σ29 and below are treated as special grain boundaries, and the other grain boundaries are treated as random grain boundaries, at the grain boundary triple points analyzed from OIM, all three grain boundaries constituting the grain boundary triple points are special grains. The ratio of J3, which is a boundary, to all grain boundary triple points is NF _J3 , and two grain boundaries that constitute the grain boundary triple point are special grain boundaries, and one is a random grain boundary. When the ratio is NF _J2 ,
0.20<(NF _J2 /(1-NF _J3 )) ^0.5 ≦0.45
shall be satisfied.

Here, when (NF _J2 / (1 - NF _J3 )) ^0.5 exceeds 0.45, the network length of random grain boundaries becomes relatively short and the network length of special grain boundaries becomes long. The burr height during machining increases. On the other hand, if (NF _J2 / (1 - NF _J3 )) ^0.5 is less than 0.20, it will essentially become a processed structure, the yield strength will exceed 500 MPa, and the curling tendency of the coil will deteriorate when the plate is made thicker. This may lead to a decrease in productivity. Therefore, in the present embodiment, (NF _J2 /(1-NF _J3 )) ^0.5 is set to be within the range of more than 0.20 and less than or equal to 0.45.
Note that the lower limit of (NF _J2 / (1-NF _J3 )) ^0.5 is preferably 0.21 or more, more preferably 0.22 or more, and even more preferably 0.23 or more. preferable. On the other hand, the upper limit of (NF _J2 /(1-NF _J3 )) ^0.5 is preferably 0.40 or less, more preferably 0.35 or less.

(Conductivity: 75% IACS or higher)
By setting the electrical conductivity of the copper alloy for electronic/electrical equipment of this embodiment to 75% IACS or higher, it can be used satisfactorily as parts for electronic/electrical equipment such as connectors, press-fit terminals, bus bars, etc. I can do it.
Note that the conductivity is preferably 77% IACS or more, more preferably 80% IACS or more, and even more preferably 85% IACS or more.

(0.2% proof stress: 200MPa or more and 500MPa or less)
The copper alloy for electronic and electrical equipment of this embodiment has a 0.2% yield strength of 200 MPa or more, making it particularly suitable as a material for parts for electronic and electrical equipment such as terminals such as connectors and press-fits, and bus bars. Become something. In addition, in this embodiment, the 0.2% proof stress when performing a tensile test in a direction parallel to the rolling direction is 200 MPa or more. When manufacturing connectors, press-fit terminals, bus bars, etc. by pressing, coil-wound strips are used to improve productivity, but if the 0.2% proof stress exceeds 500 MPa, the coil winding is Habits develop and productivity declines. Therefore, the 0.2% proof stress is preferably 500 MPa or less.
The lower limit of the above-mentioned 0.2% proof stress is preferably 220 MPa or more, more preferably 250 MPa or more. Further, the upper limit of the 0.2% proof stress is preferably 470 MPa or less, more preferably 460 MPa or less, and even more preferably 450 MPa or less.

(Residual stress rate: 70% or more)
As mentioned above, in the copper alloy for electronic and electrical equipment according to this embodiment, the residual stress rate is 70% or more at 150° C. for 500 hours.
When the residual stress rate under these conditions is high, permanent deformation can be suppressed to a small level even when used in a high-temperature environment, and a decrease in contact pressure can be suppressed. Therefore, the copper alloy for electronic/electrical equipment according to this embodiment can be applied as a terminal used in a high-temperature environment such as around the engine room of an automobile. In this embodiment, the residual stress rate in a stress relaxation test conducted in a direction parallel to the rolling direction is 70% or more at 150° C. for 500 hours.
The residual stress rate is preferably 75% or more at 150°C for 500 hours, and more preferably 80% or more at 150°C for 500 hours.

Next, a method for manufacturing a copper alloy for electronic and electrical equipment according to this embodiment having such a configuration will be described with reference to the flowchart shown in FIG. 1.

(melting/casting process S01)
First, the above-mentioned elements are added to a molten copper obtained by melting a copper raw material to adjust the composition, thereby producing a molten copper alloy. Note that for the addition of various elements, simple elements, mother alloys, etc. can be used. Moreover, a raw material containing the above-mentioned elements may be melted together with a copper raw material. Additionally, recycled materials and scrap materials of this alloy may be used. Here, the molten copper is preferably so-called 4NCu with a purity of 99.99 mass% or more, or so-called 5NCu with a purity of 99.999 mass% or more. In the melting process, in order to suppress the oxidation of Sn, Ni, and Zn and to reduce the hydrogen concentration, atmospheric melting is performed in an inert gas atmosphere (e.g. Ar gas) with a low vapor pressure of H ₂ O, and the retention during melting is It is preferable to keep the time to a minimum.

Then, the molten copper alloy whose composition has been adjusted is poured into a mold to produce an ingot. Note that when considering mass production, it is preferable to use a continuous casting method or a semi-continuous casting method.
The cooling rate of the molten metal is preferably 0.1°C/sec or more, more preferably 0.5°C/sec or more.

(Homogenization step S02)
Next, heat treatment is performed to homogenize the obtained ingot. Sn, Ni, and Zn may segregate and concentrate inside the ingot during the solidification process.
Therefore, in order to eliminate or reduce these segregations, the ingot is heated to a temperature of 300°C or more and 900°C or less. Two or more elements are homogeneously diffused, or one or more elements selected from Sn, Ni, and Zn are dissolved in the matrix. Note that this homogenization step S02 is preferably carried out in a non-oxidizing or reducing atmosphere.

(Hot working process S03)
Since segregation of Sn, Ni, and Zn tends to occur at grain boundaries, the presence of Sn, Ni, and Zn segregation makes it difficult to control the grain boundary triple point.
Therefore, in order to thoroughly homogenize the structure, hot working is performed after the above-mentioned homogenization step S02. The total processing rate of hot working is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. The processing method in this hot working step S03 is not particularly limited, and for example, rolling, wire drawing, extrusion, groove rolling, forging, pressing, etc. can be adopted. Further, the hot working temperature is preferably within a range of 400°C or more and 900°C or less.

(Solution step S04)
In order to thoroughly eliminate the segregation of Sn, Ni, and Zn at grain boundaries, solution heat treatment is performed after the above-mentioned hot working step S03. The conditions for the solution treatment step S04 are preferably such that the heating temperature is in the range of 500° C. or more and 900° C. or less, and the holding time at the heating temperature is in the range of 1 second or more and 10 hours or less. This solution treatment step S04 may also serve as the above-mentioned hot working step S03. In that case, the end temperature of hot working may be set to exceed 500°C.

(Rough processing step S05)
Rough machining is performed to process into a predetermined shape. In addition, in this rough processing step S05, warm processing at 100° C. or higher and 350° C. or lower is performed at least once. By performing warm working at 100°C or more and 350°C or less, it is possible to increase the extremely small recrystallized area during processing, and the structure is randomized during recrystallization in the subsequent intermediate heat treatment step S06. At the same time, the total number of random grain boundaries can be increased. When warm working is performed once, it is performed in the final step of the rough working step S05. Furthermore, instead of warm working, heat generated during processing may be utilized by increasing the processing rate per processing step. In that case, for example, rolling is preferably carried out at a processing rate of 15% or more per pass, preferably 20% or more, and more preferably 30% or more. It is preferable to carry out the warm working two or more times. The temperature of the warm working is preferably 150°C or more and 350°C or less, more preferably more than 200°C and 350°C or less.

(Intermediate heat treatment step S06)
After the rough processing step S05, heat treatment is performed for the purpose of recrystallization structure to increase the number of random grain boundaries and softening to improve workability. The heat treatment method is not particularly limited, but the heat treatment is preferably performed at a holding temperature of 400° C. or more and 900° C. or less and a holding time of 10 seconds or more and 10 hours or less in a non-oxidizing atmosphere or a reducing atmosphere. Further, the cooling method after heating is not particularly limited, but it is preferable to adopt a method such as water quenching that has a cooling rate of 200° C./min or more.
Note that the rough processing step S05 and the intermediate heat treatment step S06 may be performed repeatedly.

(Finishing process S07)
Finishing is performed to process the copper material after the intermediate heat treatment step S06 into a predetermined shape. In this finishing step S07, warm working at 50° C. or more and less than 300° C. is performed at least once in order to improve stress relaxation resistance. By performing warm working at a temperature of 50° C. or more and less than 300° C., the stress relaxation resistance improves because the dislocations introduced during the working are rearranged. In the finishing step S07, the processing method and processing rate vary depending on the final shape, but rolling may be performed when forming a strip or a plate. Further, steps other than one or more warm working steps may be performed by normal cold working. Instead of warm working at 50° C. or more and less than 300° C., the processing rate per processing step may be increased and the heat generated during processing may be utilized. In that case, for example, in rolling, the processing rate per pass may be set to 10% or more.
In addition, the processing rate will be appropriately selected so as to approximate the final shape, but in order to increase the tensile strength between 200 MPa and 500 MPa by work hardening in the finishing process S07, the upper limit of the processing rate must be set to 90 MPa. % or less, more preferably 85% or less, and most preferably 80% or less.

(Final heat treatment step S08)
Next, the plastically worked material obtained in the finishing step S07 is subjected to finishing heat treatment in order to improve stress relaxation resistance and harden by low-temperature annealing, or to remove residual strain. The heat treatment temperature is preferably within a range of 100°C or higher and 800°C or lower. In this finishing heat treatment step S08, it is necessary to set heat treatment conditions (temperature, time, cooling rate) in order to suppress the number of special grain boundaries at grain boundary triple points due to recrystallization. For example, in the range of 200°C to 350°C, the holding time is preferably 10 seconds or more and 10 hours or less. This heat treatment is preferably performed in a non-oxidizing atmosphere or a reducing atmosphere. The method of heat treatment is not particularly limited, but from the viewpoint of reducing manufacturing costs, high temperature and short time heat treatment using a continuous annealing furnace is preferred.
Furthermore, the above-mentioned finish processing step S07 and finish heat treatment step S08 may be repeatedly performed.

In this way, the copper alloy for electronic and electrical equipment (copper alloy plate and strip material for electronic and electrical equipment) of this embodiment is produced. There is no particular upper limit for the thickness of copper alloy sheet strips for electronic and electrical equipment, but when pressing copper alloy sheet strips for electronic and electrical equipment into connectors, terminals, and bus bars, the thickness must be 5.0 mm. Exceeding this will significantly increase the load on the press and reduce productivity per unit time, resulting in higher costs. For this reason, in this embodiment, it is preferable that the thickness of the copper alloy plate strip for electronic/electrical equipment is greater than 0.5 mm and less than or equal to 5.0 mm. Note that the lower limit of the thickness of the copper alloy plate strip for electronic and electrical equipment is preferably greater than 1.0 mm, and more preferably greater than 2.0 mm.

Here, the copper alloy sheet strip for electronic and electrical equipment of this embodiment may be used as is for parts for electronic and electrical equipment, but it should be noted that the film thickness of 0.1 to A Sn plating layer or Ag plating layer with a thickness of about 100 μm may be formed.
Furthermore, by using the copper alloy for electronic/electrical equipment (copper alloy sheet material for electronic/electrical equipment) of this embodiment as a material and performing punching, bending, etc., terminals such as connectors and press-fits, etc. Parts for electronic and electrical equipment such as bus bars are molded.

According to the copper alloy for electronic/electrical equipment of this embodiment configured as above, the total content of one or more elements selected from Sn, Ni, and Zn is 0.05 mass%. Since it is within the range of less than 0.4 mass%, one or more elements selected from Sn, Ni, and Zn are dissolved in the copper matrix, resulting in a significant decrease in electrical conductivity. It is possible to improve strength and stress relaxation resistance without causing

Then, using the plane perpendicular to the rolling width direction as the observation plane, the matrix is measured by the EBSD method over a measurement area of 10,000 μm ² or more in steps with a measurement interval of 1/10 or less of the average grain size, The measurement points analyzed by the data analysis software OIM with a CI value of 0.1 or less are analyzed, and the grain boundaries are defined as grain boundaries between the measurement points where the orientation difference between adjacent measurements is 15° or more, and the correspondence is Σ29 or less. When grain boundaries are special grain boundaries and other grain boundaries are random grain boundaries, at the grain boundary triple points analyzed from OIM, all three grain boundaries constituting the grain boundary triple points are special grain boundaries. NF _J3 is the ratio to the grain boundary triple points, and NF _J2 is the ratio of J2 to the total grain boundary triple points, where two grain boundaries constituting the grain boundary triple point are special grain boundaries and one is a random grain boundary. When,
0.20<(NF _J2 /(1-NF _J3 )) ^0.5 ≦0.45
Since the following holds true, the length of the random grain boundary network is long, and fractures along the grain boundaries occur quickly during press processing, resulting in excellent press punching workability.

Furthermore, in the copper alloy for electronic and electrical equipment according to the present embodiment, the 0.2% yield strength when subjected to a tensile test in a direction parallel to the rolling direction is within the range of 200 MPa or more and 500 MPa or less, Since the conductivity is said to be 75% IACS or higher, it is suitable for thick-walled electronic and electrical equipment parts for high voltage and large current applications, and is suitable for electronic parts such as connectors, press-fit terminals, bus bars, etc.・Particularly suitable as a material for parts for electrical equipment.

In addition, the copper alloy for electronic and electrical equipment of this embodiment has a residual stress rate of 70% or more at 150°C for 500 hours, so even when used in a high-temperature environment, there is no permanent deformation. For example, it is possible to suppress a decrease in contact pressure of a connector terminal or the like. Therefore, it can be applied as a material for parts for electronic devices used in high-temperature environments such as engine rooms.

Furthermore, since the copper alloy sheet strip for electronic/electrical equipment of this embodiment is composed of the above-mentioned copper alloy for electronic/electrical equipment, it is possible to use this copper alloy plate/strip for electronic/electrical equipment. It is possible to manufacture parts for electronic and electrical equipment such as connectors, press-fit terminals, bus bars, etc.
In addition, when a Sn plating layer or an Ag plating layer is formed on the surface, it is particularly suitable as a material for parts for electronic and electrical equipment such as terminals such as connectors and press-fits, and bus bars.

Furthermore, the parts for electronic and electrical equipment (terminals such as connectors and press-fits, bus bars, etc.) of this embodiment are made of the above-mentioned copper alloy for electronic and electrical equipment, so they are larger and thicker. can also exhibit excellent properties.

The embodiments of the present invention have been described above, such as copper alloys for electronic and electrical equipment, copper alloy sheets and strips for electronic and electrical equipment, and parts for electronic and electrical equipment (terminals, bus bars, etc.). There is no limitation, and changes can be made as appropriate without departing from the technical idea of the invention.
For example, in the above-described embodiment, an example of a method for manufacturing a copper alloy for electronic and electrical equipment has been described, but the method for manufacturing a copper alloy for electronic and electrical equipment is not limited to that described in the embodiment. , or may be manufactured by appropriately selecting an existing manufacturing method.

Below, the results of a confirmation experiment conducted to confirm the effects of the present invention will be explained.
A copper raw material made of oxygen-free copper (ASTM B152 C10100) with a purity of 99.99 mass% or more was prepared, placed in a high-purity graphite crucible, and high-frequency melted in an atmosphere furnace with an Ar gas atmosphere. One or more elements selected from Sn, Ni, and Zn are added to the obtained molten copper to prepare the composition shown in Table 1, and the molten metal is poured into a carbon mold to produce an ingot. I put it out. Thereafter, a part of the ingot was cut and machined to obtain an ingot with a thickness of 50 mm, a width of 100 mm, and a length of 100 mm.
Thereafter, in an Ar gas atmosphere, heating was performed at 800° C. for 4 hours using an electric furnace to perform a homogenization treatment.

The ingot after the homogenization heat treatment was hot forged to obtain a plate material with a height of about 25 mm and a width of about 150 mm. Hot forging should be carried out at a temperature of 500°C or higher, and when the surface temperature falls below 500°C, it is reheated in an electric furnace maintained at 800°C, and when the surface temperature reaches approximately 600°C, it is heated again. Interval forging was carried out. The temperature at the end of hot forging was 500°C or higher. After the hot forging was completed, solution heat treatment was performed for 1 min in an electric furnace heated to 800°C.
Thereafter, the rolling roll was heated to 300° C., and rough rolling was performed until the thickness shown in Table 1 was achieved.

After rough rolling, intermediate heat treatment was performed using an electric furnace and a salt bath furnace under the temperature conditions listed in the table. The heat treatment using an electric furnace was performed in an Ar atmosphere. The average grain size after the intermediate heat treatment was adjusted to fall between 10 μm and less than 30 μm for those conducted at heat treatment temperatures of 500° C. and 600° C. Further, those heat-treated at 700°C and 800°C were adjusted to have a thickness of 30 μm or more and less than 50 μm.
Note that the average crystal grain size after the intermediate heat treatment was investigated as follows. The surface perpendicular to the rolling width direction, that is, the TD (Transverse Direction) surface, is used as the observation surface, and after mirror polishing and etching, the photograph is taken with an optical microscope so that the rolling direction is on the side of the photograph, Observation was performed with a 1000x field of view (approximately 300 x 200 μm ² ). Then, according to the cutting method of JIS H 0501, the crystal grain size is determined by drawing 5 line segments of a predetermined length in the vertical and horizontal directions of the photo, counting the number of crystal grains that can be completely cut, and averaging the average value of the cut lengths. It was calculated as the crystal grain size.

The plate material that had been subjected to intermediate heat treatment was cut and surface ground to remove the oxide film. Thereafter, the rolling rolls were heated to 200° C., and finish rolling (finishing) was performed at the rolling rate shown in Table 1 to produce thin plates having the thickness shown in Table 1.
After finishing rolling (finishing), finish heat treatment was performed using a hot plate or a salt bath furnace under the conditions listed in Table 1, followed by water quenching to produce a thin plate for property evaluation.

Then, the following items were evaluated. The evaluation results are shown in Table 2.

(Grain boundary triple point ratio)
Using a cross section perpendicular to the rolling width direction, that is, the TD plane (Transverse direction) as the observation plane, grain boundaries (special grain boundaries and random grain boundaries) and grain boundaries were determined as follows using an EBSD measurement device and OIM analysis software. The three points of the field were measured. After mechanical polishing was performed using waterproof abrasive paper and diamond abrasive grains, final polishing was performed using colloidal silica solution. And EBSD measurement devices (FEI QUANTA FEG 450, EDAX / TSL (currently AMETEK) Oim Data Colection) and analysis software (EDAX / TSL (currently AMETEK) Oim DATA A) Nalysis Ver.7.3 1), the orientation difference of each crystal grain is analyzed except for measurement points where the CI value is 0.1 or less at an electron beam acceleration voltage of 20 kV and a measurement interval of 0.25 μm, and adjacent measurement A grain boundary was defined as a grain boundary between measurement points where the orientation difference between the points was 15° or more. Then, the average particle size was determined by Area Fraction. After that, at the measurement interval step where the average grain size is 1/10 or less, the CI value is 0.1 at a measurement area of 10000 μm ² or more in multiple fields of view so that a total of 1000 or more crystal grains are included. The orientation difference of each crystal grain was analyzed except for the following measurement points, and grain boundaries were defined between measurement points where the orientation difference between adjacent measurement points was 15° or more. Further, for the three grain boundaries constituting each grain boundary triple point, special grain boundaries and random grain boundaries were identified using the value of the CSL signma value calculated at the neighbor grid point. Corresponding grain boundaries exceeding Σ29 were regarded as random grain boundaries.

(mechanical properties)
A No. 13B test piece specified in JIS Z 2241 was taken from the strip material for property evaluation, and the 0.2% proof stress was measured by the offset method of JIS Z 2241. Note that the test piece was taken in a direction parallel to the rolling direction.

(conductivity)
A test piece with a width of 10 mm and a length of 150 mm was taken from the strip for characteristic evaluation, and its electrical resistance was determined by a four-terminal method. In addition, the dimensions of the test piece were measured using a micrometer, and the volume of the test piece was calculated. Then, the conductivity was calculated from the measured electrical resistance value and volume. In addition, the test piece was taken so that its longitudinal direction was parallel to the rolling direction of the strip material for characteristic evaluation.

(Stress relaxation properties)
In the stress relaxation property test, stress was applied using a method similar to the cantilever screw method of the Japan Copper Brass Association technical standard JCBA-T309:2004, and the residual stress rate was measured after holding at a temperature of 150°C for 500 hours. .
The test method was to take a test piece (width 10 mm) from each strip for characteristic evaluation in a direction parallel to the rolling direction, and adjust the initial deflection displacement so that the maximum stress on the surface of the test piece was 80% of the proof stress. was set to 2 mm, and the span length was adjusted. The above maximum surface stress is determined by the following formula.
Maximum surface stress (MPa) = 1.5Etδ ₀ /L _s ²
however,
E: Young's modulus (MPa)
t: Thickness of sample (mm)
δ ₀ : Initial deflection displacement (2mm)
_Ls : Span length (mm)
It is.
The residual stress rate was measured from the bending tendency after being held at a temperature of 150° C. for 500 hours, and the stress relaxation resistance was evaluated. Note that the residual stress rate was calculated using the following formula.
Residual stress rate (%) = (1-δ _t /δ ₀ ) × 100
however,
_δt : Permanent deflection displacement (mm) after being held at 150°C for 500 hours - Permanent deflection displacement (mm) after being kept at room temperature for 24 hours
δ ₀ : Initial deflection displacement (mm)
It is.

(Punching workability)
A large number of circular holes (φ8 mm) were punched out from the strip material for characteristic evaluation using a mold, and evaluation was performed by measuring the burr height.
The die clearance was approximately 3% relative to the plate thickness, and punching was performed at a punching speed of 50 spm (stroke per minute). The burr height was measured by observing the cut surface on the punched side, measuring at 10 or more points, and evaluating it as a percentage of the plate thickness.
If the highest burr height is 1.0% or less of the plate thickness, it is evaluated as "◎", if it exceeds 1.0% and is 3.0% or less, it is evaluated as "○", and if it is 3.0%, it is evaluated as "◎". Those that exceeded the criteria were rated "×".

In Comparative Example 1, the Sn content was higher than the range of the present invention, and the conductivity was low. Therefore, stress relaxation resistance and punchability were not evaluated.
In Comparative Example 2, the Ni content was lower than the range of the present invention, so the stress relaxation resistance was low. Therefore, evaluation of punchability was not performed.
In Comparative Example 3, (NF _J2 /(1-NF _J3 )) ^0.5 was 0.50, which was larger than the range of the present invention, and the network length of random grain boundaries was shortened, resulting in poor punching workability.
In Comparative Example 4, (NF _J2 /(1-NF _J3 )) ^0.5 was 0.19, which was smaller than the range of the present invention, and the 0.2% proof stress was higher than necessary. Therefore, evaluation of electrical conductivity, stress relaxation resistance, and punching workability was not performed.

On the other hand, it is confirmed that the examples of the present invention are excellent in 0.2% yield strength, electrical conductivity, stress relaxation resistance, and punching workability.
From the above, according to the examples of the present invention, it is possible to provide a copper alloy for electronic/electrical equipment and a copper alloy plate/strip material for electronic/electrical equipment that has excellent conductivity, strength, stress relaxation resistance, and punching workability. confirmed.

Claims (9)

Contains one or more elements selected from Sn, Ni, and Zn in a total amount of 0.05 mass% or more and less than 0.4 mass%, the remainder consisting of Cu and inevitable impurities,
Using the plane including the rolling direction and the rolling direction as the observation surface, the matrix was measured using the EBSD method over a measurement area of 10,000 μm ² or more, excluding measurement points where the CI value was 0.1 or less at a measurement interval of 0.25 μm. , analyze the orientation difference of each crystal grain, define the grain boundary between the measurement points where the orientation difference between adjacent measurement points is 15 degrees or more, calculate the average grain size by Area Fraction, and calculate the average grain size by 10 minutes of the average grain size. The CI value analyzed by the data analysis software OIM is measured in steps with a measurement interval of 1 or less, and the measurement area is 10,000 μm ² or more in multiple fields of view so that a total of 1,000 or more crystal grains are included. Analysis is performed excluding measurement points where the orientation difference is 0.1 or less, and grain boundaries are defined between measurement points where the orientation difference between adjacent measurements is 15° or more, corresponding grain boundaries with Σ29 or less are defined as special grain boundaries, and other points are defined as special grain boundaries. When random grain boundaries are used, at the grain boundary triple points analyzed from OIM,
All three grain boundaries constituting the grain boundary triple point are special grain boundaries.The ratio of J3 to the total grain boundary triple point is NF _J3 , and two grain boundaries constituting the grain boundary triple point are special grain boundaries, When the ratio of J2, one of which is a random grain boundary, to the total grain boundary triple points is NF _J2 ,
A copper alloy for electronic and electrical equipment, characterized in that 0.23 < (NF _J2 / (1-NF _J3 )) ^0.5 ≦0.45. The copper alloy for electronic and electrical equipment according to claim 1, characterized in that the conductivity is 75% IACS or higher. 2. The electronic/electrical device according to claim 1 or 2, wherein the 0.2% yield strength when subjected to a tensile test in a direction parallel to the rolling direction is within the range of 200 MPa or more and 500 MPa or less. Copper alloy. The copper alloy for electronic and electrical equipment according to any one of claims 1 to 3, characterized in that the residual stress rate is 70% or more at 150°C for 500 hours. A copper alloy sheet strip for electronic and electrical equipment, which is made of the copper alloy for electronic and electrical equipment according to any one of claims 1 to 4, and has a thickness of more than 0.5 mm. Material. The copper alloy plate strip for electronic/electrical equipment according to claim 5, having a Sn plating layer or an Ag plating layer on the surface. A component for electronic/electrical equipment, characterized by being made of the copper alloy plate strip material for electronic/electrical equipment according to claim 5 or 6. A terminal comprising the copper alloy plate strip material for electronic/electrical equipment according to claim 5 or 6. A bus bar comprising the copper alloy plate strip material for electronic/electrical equipment according to claim 5 or 6.

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