阅读说明：本技术 电子电气设备用铜合金﹑电子电气设备用铜合金板条材、电子电气设备用组件、端子及汇流排 (Copper alloy for electronic and electrical equipment, copper alloy strip for electronic and electrical equipment, module for electronic and electrical equipment, terminal, and bus bar ) 是由 松永裕隆 川崎健一郎 森广行 牧一诚 秋坂佳辉 于 2019-03-28 设计创作，主要内容包括：该电子电气设备用铜合金包含Mg：0.15质量％以上且小于0.35质量％及P：0.0005质量％以上且小于0.01质量％,剩余部分由Cu及不可避免的杂质构成,Mg量〔Mg〕与P量〔P〕以质量比计满足〔Mg〕+20×〔P〕＜0.5,晶界三重点的三个晶界全部为特殊晶界的J3与所有晶界三重点的比例NF<Sub>J3</Sub>及晶界三重点的两个晶界为特殊晶界且一个晶界为随机晶界的J2与所有晶界三重点的比例NF<Sub>J2</Sub>满足0.20＜(NF<Sub>J2</Sub>/(1-NF<Sub>J3</Sub>))<Sup>0.5</Sup>≤0.45。(The copper alloy for electronic and electrical equipment contains Mg: 0.15 mass% or more and less than 0.35 mass%, and P: 0.0005 mass% or more and less than 0.01 mass%, the remainder beingThe balance being Cu and unavoidable impurities, the mass ratio of Mg amount [ Mg ] to P amount [ P ] satisfying [ Mg ] +20 × [ P ] < 0.5, the ratio NF of J3 in which all three grain boundaries of the grain boundary triple point are special grain boundaries to all the grain boundary triple points being J3 J3 And the proportion NF of J2 with two grain boundaries of the grain boundary triple points as special grain boundaries and one grain boundary as random grain boundary to all the grain boundary triple points J2 Satisfies 0.20 < (NF) J2 /(1‑NF J3 )) 0.5 ≤0.45。)

1. A copper alloy for electronic and electrical equipment, characterized in that,

mg is contained in a range of 0.15 to less than 0.35 mass%, P is contained in a range of 0.0005 to less than 0.01 mass%, and the balance is Cu and unavoidable impurities,

the content [ Mg ] of Mg and the content [ P ] of P satisfy the following relationship in terms of mass ratio,

〔Mg〕+20×〔P〕＜0.5，

and 10000 μm was measured at a measurement interval of 0.25 μm for the parent phase by the EBSD method using a plane orthogonal to the width direction of rolling as an observation plane²The above measurement areas were analyzed by excluding the measurement points having the reliability index CI value of 0.1 or less analyzed by the data analysis software OIM, and when the grain boundaries were set between the measurement points having the misorientation between adjacent measurement points exceeding 15 °, the corresponding grain boundaries of Σ 29 or less were set as special grain boundaries, and the other grain boundaries were set as random grain boundaries, among the grain boundary triple points according to the OIM analysis,

the proportion of J3 in which all three grain boundaries constituting the grain boundary triple points are special grain boundaries to all the grain boundary triple points was NF_J3The ratio of J2 in which two grain boundaries constituting grain boundary triple points are special grain boundaries and one grain boundary is random grain boundaries to all the grain boundary triple points is NF_J2When the temperature of the water is higher than the set temperature,

0.20＜(NF_J2/(1-NF_J3))^0.5less than or equal to 0.45.

2. The copper alloy for electronic and electrical equipment according to claim 1,

the conductivity exceeded 75% IACS.

3. The copper alloy for electronic and electrical equipment according to claim 1 or 2,

the content [ Mg ] of Mg and the content [ P ] of P satisfy the following relationship in terms of mass ratio,

〔Mg〕/〔P〕≤400。

4. the copper alloy for electronic and electrical equipment according to any one of claims 1 to 3,

the 0.2% yield strength in a tensile test conducted in a direction parallel to the rolling direction is in the range of 200MPa or more and 450MPa or less.

5. The copper alloy for electronic and electrical equipment according to any one of claims 1 to 4,

the residual stress rate is 75% or more under the conditions of 150 ℃ and 1000 hours.

6. A copper alloy strip for electrical and electronic equipment, which comprises the copper alloy for electrical and electronic equipment according to any one of claims 1 to 5 and has a thickness of more than 0.5 mm.

7. The copper alloy strip for electronic and electrical equipment according to claim 6,

the surface of the glass has a tin plating layer or a silver plating layer.

8. A package for electrical and electronic equipment, comprising the copper alloy strip for electrical and electronic equipment according to claim 6 or 7.

9. A terminal comprising the copper alloy strip for electrical and electronic equipment according to claim 6 or 7.

10. A bus bar comprising the copper alloy strip for electronic/electrical equipment according to claim 6 or 7.

Technical Field

The present invention relates to a copper alloy for electronic and electrical devices suitable for terminals such as connectors and pressure-sensitive adhesives and components for electronic and electrical devices such as busbars, a copper alloy strip for electronic and electrical devices made of the copper alloy for electronic and electrical devices, a component for electronic and electrical devices, a terminal, and a busbar.

The present application claims priority based on patent application No. 2018-069095, which was filed in japan on 30/3/2018, and the contents of which are incorporated herein by reference.

Background

Conventionally, highly conductive copper or copper alloy has been used for components for electronic/electrical devices such as terminals and bus bars, such as connectors and pressure-sensitive adhesives.

With the increase in current of electronic devices, electrical devices, and the like, there have been attempts to increase the size and thickness of electronic/electrical device packages used in these electronic devices, electrical devices, and the like, in order to reduce the current density and to diffuse heat due to joule heating. Therefore, materials constituting the electronic and electrical device module are required to have high electrical conductivity, punching workability in press working, and good bending workability. Further, a connector terminal or the like used in a high-temperature environment such as an engine room of an automobile is also required to have a stress relaxation resistance.

As a material used for a component for an electronic/electrical device such as a terminal and a bus bar of a connector or a pressure-bonded body, for example, a Cu — Mg alloy is proposed in patent documents 1 and 2.

In the Cu — Mg alloy described in patent document 1, since the content of P is as high as 0.08 to 0.35 mass%, cold workability and bending workability are insufficient, and it is difficult to mold a component for electronic and electrical equipment having a predetermined shape.

In the Cu — Mg alloy described in patent document 2, since the Mg content is 0.01 to 0.5 mass% and the P content is 0.01 to 0.5 mass%, coarse crystals are generated, and cold workability and bending workability are insufficient.

In the above Cu — Mg alloy, Mg increases the viscosity of the copper alloy melt, and therefore, if P is not added, the castability is lowered.

As described above, with the recent increase in current of electronic devices, electric devices, and the like, the material constituting the module for electronic and electric devices is being thickened. However, with an increase in thickness, there is a problem that the height of burrs generated at the time of punching increases and punching workability at the time of press working decreases.

Patent document 1: japanese laid-open patent publication No. 2007-056297

Patent document 2: japanese patent laid-open No. 2014-114464

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a copper alloy for electronic and electrical equipment, a copper alloy plate bar for electronic and electrical equipment, and a module for electronic and electrical equipment, a terminal, and a bus bar each of which is excellent in conductivity, strength, bending workability, stress relaxation resistance, castability, and blanking workability.

In order to solve the problem, the present inventors have conducted extensive studies and, as a result, have obtained the following findings: by setting the contents of Mg and P contained in the alloy within the range of the predetermined relational expression, coarsening of crystals containing Mg and P can be suppressed, and strength, stress relaxation resistance, and castability can be improved without lowering workability.

In the above copper alloy, the matrix phase was analyzed by the EBSD method with the surface perpendicular to the width direction of rolling as the observation surface. As a result, the following findings were obtained: by defining the ratio of the special grain boundaries and the random grain boundaries constituting the grain boundary triple point, cracks are likely to spread along the grain boundaries during press working, and punching workability during press working can be improved.

In order to solve the problem, a copper alloy for electronic and electrical equipment according to an aspect of the present invention includes Mg in a range of 0.15 mass% or more and less than 0.35 mass%, P in a range of 0.0005 mass% or more and less than 0.01 mass%, and the remainder is made up of Cu and unavoidable impurities, and the content [ Mg ] of Mg and the content [ P ] of P satisfy a relationship of [ Mg ] +20 × [ P ] < 0.5 in terms of a mass ratio, and a surface orthogonal to a width direction of rolling is used as an observation surface, and 10000 μm is measured at a step length of 0.25 μm measurement interval for a parent phase by an EBSD method²The above measurement areas were analyzed by excluding the measurement points having the reliability index CI value of 0.1 or less analyzed by the data analysis software OIM, and when the grain boundaries were set between the measurement points having the misorientation between adjacent measurement points exceeding 15 °, the corresponding grain boundaries of Σ 29 or less were special grain boundaries, and the other grain boundaries were random grain boundaries, in the grain boundary triple point according to the OIM analysis, the proportion of J3 where all three grain boundaries constituting the grain boundary triple point were special grain boundaries to all the grain boundary triple points was NF, and the proportion of all the grain boundary triple points was NF_J3The ratio of J2 in which two grain boundaries constituting grain boundary triple points are special grain boundaries and one grain boundary is random grain boundaries to all the grain boundary triple points is NF_J20.20 < (NF) > (_J2/(1-NF_J3))⁰ _. ⁵Less than or equal to 0.45.

The EBSD method is an Electron reflection Diffraction (EBSD) method using a scanning Electron microscope with a back-scattered Electron Diffraction imaging system, and OIM is data analysis software (OIM) for analyzing crystal Orientation using measurement data obtained by EBSD. The CI value is a reliability Index (Confidence Index), and is a value that is displayed as a value indicating reliability of crystal orientation when analyzed by using the Analysis software OIM Analysis (ver.7.2) of the EBSD device (for example, えば, "EBSD this: OIM を uses するにあたって (modified version 3) wood first, 9 months in 2009, and TSL ソリューションズ company [ for example," EBSD reader "in using OIM (modified version 3)" suzuki clean, 9 months in 2009, TSL Solutions gmbh ]).

Here, when the structure of the measurement point measured by the EBSD method and analyzed by OIM is a processed structure, the reliability of determining the crystal orientation is low and the CI value is low because the crystal pattern is not clear. In particular, when the CI value is 0.1 or less, the tissue at the measurement point is determined to be a processed tissue.

And, the special grain boundaries are defined as the following grain boundaries: crystallographically, the value Σ defined according to CSL theory (Kronberg et al: trans. Met. Soc. AIME,185,501(1949)) belongs to the corresponding grain boundary of 3 ≦ Σ ≦ 29, and the lattice orientation defect Dq at the inherent correspondence site in the corresponding grain boundary satisfies Dq ≦ 15 °/Σ 1/2 (D.G.Brandon: acta. Metallurgica. Vol.14, p.1479, (1966)).

On the other hand, the random grain boundaries mean grain boundaries other than special grain boundaries satisfying Dq ≦ 15 °/Σ 1/2, which belong to a corresponding orientation relationship in which Σ is 29 or less. That is, the special grain boundaries are grain boundaries satisfying Dq ≦ 15 °/Σ 1/2 in the corresponding orientation relationship in which Σ is 29 or less, and the grain boundaries other than the special grain boundaries are random grain boundaries.

In addition, as the grain boundary triple point, there are four types as follows: j0 with all three grain boundaries being random grain boundaries, J1 with one grain boundary being a special grain boundary and two grain boundaries being random grain boundaries, J2 with two grain boundaries being special grain boundaries and one grain boundary being random grain boundaries, and J3 with all three grain boundaries being special grain boundaries.

Therefore, all of the three grain boundaries constituting the grain boundary triple point are characterizedProportion NF of J3 with great grain boundary and triple points with all grain boundaries_J3(the ratio of the number of J3 to the number of all grain boundary triple points) was determined from NF_J3J3/(J0+ J1+ J2+ J3).

Further, the proportion NF of J2 in which two grain boundaries constituting the grain boundary triple points are special grain boundaries and one grain boundary is a random grain boundary to all the grain boundary triple points_J2(the ratio of the number of J2 to the number of all grain boundary triple points) was determined from NF_J2J2/(J0+ J1+ J2+ J3).

According to the copper alloy for electronic and electrical equipment having the above configuration, since the content of Mg is set to be in the range of 0.15 mass% or more and less than 0.35 mass%, the strength and the stress relaxation resistance can be improved without significantly decreasing the electrical conductivity by solid-dissolving Mg in the parent phase of copper.

Further, since P is contained in a range of 0.0005 mass% or more and less than 0.01 mass%, the viscosity of the copper alloy melt containing Mg can be reduced, and castability can be improved.

Further, since the content [ Mg ] of Mg and the content [ P ] of P satisfy the relationship of [ Mg ] +20 × [ P ] < 0.5 in terms of mass ratio, the generation of coarse crystals containing Mg and P can be suppressed, and the reduction of cold workability and bending workability can be suppressed.

Then, 10000 μm were measured at a measurement interval of 0.25 μm for the parent phase by the EBSD method using a plane orthogonal to the width direction of rolling as an observation plane²The above measurement areas were analyzed by excluding the measurement points having CI values of 0.1 or less analyzed by the data analysis software OIM, and when the grain boundaries were set between the measurement points having a misorientation of more than 15 ° between adjacent measurement points, the corresponding grain boundaries of Σ 29 or less were special grain boundaries, and the other grain boundaries were random grain boundaries, in the grain boundary triple point by the OIM analysis, the proportion of J3, in which all three grain boundaries constituting the grain boundary triple point were special grain boundaries, to all the grain boundary triple points was NF 3, and the proportion of all the grain boundary triple points was NF_J3The ratio of J2 in which two grain boundaries constituting grain boundary triple points are special grain boundaries and one grain boundary is random grain boundaries to all the grain boundary triple points is NF_J2When it is used, 0.20 < (NF) is satisfied_J2/(1-NF_J3))^0.5Less than or equal to 0.45. Therefore, cracks are likely to spread along the grain boundaries, and the punching workability during the press working can be improved.

Here, in the copper alloy for electronic and electrical equipment according to the aspect of the present invention, the electrical conductivity is preferably more than 75% IACS.

In this case, since the conductivity is sufficiently high, the copper alloy can be applied to applications in which pure copper has been conventionally used.

In the copper alloy for electronic and electrical equipment according to one aspect of the present invention, it is preferable that the content [ Mg ] of Mg and the content [ P ] of P satisfy the relationship of [ Mg ]/[ P ] ≦ 400 in terms of a mass ratio.

In this case, by defining the ratio of the content of Mg that decreases the castability to the content of P that increases the castability as described above, the castability can be reliably improved.

In the copper alloy for electronic and electrical equipment according to one aspect of the present invention, the 0.2% proof stress in the tensile test performed in the direction parallel to the rolling direction is preferably in a range of 200MPa to 450 MPa.

In this case, since the 0.2% proof stress in the tensile test in the direction parallel to the rolling direction is set to be in the range of 200MPa or more and 450MPa or less, even if a strip having a thickness of more than 0.5mm is wound in a coil shape, the coil is not scratched, the handling is easy, and high productivity can be achieved. Therefore, the copper alloy is particularly suitable for use as a component for electronic/electrical equipment such as a terminal and a bus bar of a connector or a pressure-sensitive adhesive for large current and high voltage.

In the copper alloy for electronic and electrical equipment according to one aspect of the present invention, the residual stress ratio is preferably 75% or more under the conditions of 150 ℃ and 1000 hours.

In this case, since the residual stress ratio is defined as described above, even when the connector is used in a high-temperature environment, the permanent deformation can be suppressed to a small level, and a decrease in contact pressure of the connector terminal or the like, for example, can be suppressed. Therefore, the resin composition can be suitably used as a material for electronic device modules used in high-temperature environments such as engine rooms.

A copper alloy strip for electrical and electronic equipment according to an aspect of the present invention is characterized by being made of the copper alloy for electrical and electronic equipment and having a thickness exceeding 0.5 mm.

The copper alloy strip for electronic/electrical equipment having such a structure is excellent in conductivity, strength, bending workability, stress relaxation resistance, and punching workability because it is made of the above copper alloy for electronic/electrical equipment, and is particularly suitable as a material for electronic/electrical equipment components such as terminals and bus bars of thick connectors and laminates.

Here, in the copper alloy strip for electronic and electrical equipment according to one aspect of the present invention, the surface preferably has a tin plating layer or a silver plating layer.

In this case, since the surface has a tin-plated layer or a silver-plated layer, it is particularly suitable as a material for a module for an electronic/electrical device such as a terminal or a bus bar of a connector or a laminate. In addition, in one embodiment of the present invention, "tin plating" includes pure tin plating or tin alloy plating, and "silver plating" includes pure silver plating or silver alloy plating.

A module for an electrical and electronic device according to an aspect of the present invention is characterized by being formed from the copper alloy strip for an electrical and electronic device. The module for an electrical/electronic device according to an embodiment of the present invention includes a terminal such as a connector or a pressure-sensitive adhesive, a bus bar, and the like.

Since the module for an electrical and electronic device having this structure is manufactured using the copper alloy strip for an electrical and electronic device, excellent characteristics can be exhibited even when the module is enlarged and thickened in accordance with a large current application.

A terminal according to one aspect of the present invention is characterized by being made of the copper alloy strip for electronic and electrical equipment.

The terminal having this structure is manufactured using the copper alloy strip for electronic and electrical equipment, and therefore can exhibit excellent characteristics even when the terminal is enlarged and thickened in accordance with the use of a large current.

A bus bar according to an aspect of the present invention is characterized by being made of the copper alloy strip material for an electrical and electronic device.

The bus bar having this structure is manufactured using the copper alloy strip for electronic and electrical equipment, and therefore can exhibit excellent characteristics even when the bus bar is enlarged or thickened in accordance with the use of a large current.

According to an aspect of the present invention, it is possible to provide a copper alloy for electronic and electrical equipment, a copper alloy strip for electronic and electrical equipment, and a module for electronic and electrical equipment, a terminal, and a bus bar each of which is composed of the copper alloy strip for electronic and electrical equipment, the copper alloy having excellent conductivity, strength, bending workability, stress relaxation resistance, castability, and punching workability.

Drawings

Fig. 1 is a flowchart of a method for producing a copper alloy for electronic and electrical devices according to the present embodiment.

Detailed Description

Hereinafter, a copper alloy for electronic and electrical equipment according to an embodiment of the present invention will be described.

The copper alloy for electronic and electrical equipment of the present embodiment has the following composition: mg is contained in a range of 0.15 mass% or more and less than 0.35 mass%, P is contained in a range of 0.0005 mass% or more and less than 0.01 mass%, and the remainder is composed of Cu and unavoidable impurities.

Further, the content [ Mg ] of Mg and the content [ P ] of P have the following relationship in terms of mass ratio,

〔Mg〕+20×〔P〕＜0.5。

in the present invention, it is preferable that the content [ Mg ] of Mg and the content [ P ] of P have the following relationship in terms of mass ratio,

〔Mg〕/〔P〕≤400。

in the copper alloy for electronic and electrical equipment according to the embodiment of the present invention, 0.20 < (NF)_J2/(1-NF_J3))^0.5Less than or equal to 0.45.

The measurement interval for the parent phase was 0 by the EBSD method with the surface perpendicular to the width direction of rolling as the observation surface.Step size of 25 μm was determined to be 10000 μm²The above measurement area. Next, measurement points having CI values of 0.1 or less analyzed by the data analysis software OIM were removed and analyzed, and a grain boundary was defined between measurement points where the difference in orientation between adjacent measurement points exceeded 15 °. The corresponding grain boundaries below Σ 29 are special grain boundaries, and the other grain boundaries are random grain boundaries. In the grain boundary triple points by the OIM analysis, the ratio of J3, in which all three grain boundaries constituting the grain boundary triple points are special grain boundaries, to all the grain boundary triple points was NF_J3The ratio of J2 in which two grain boundaries constituting grain boundary triple points are special grain boundaries and one grain boundary is random grain boundaries to all the grain boundary triple points is NF_J2. For these NF_J3And NF_J2，0.20＜(NF_J2/(1-NF_J3))^0.5Less than or equal to 0.45.

In the copper alloy for electronic and electrical devices according to the present embodiment, the electrical conductivity is preferably set to more than 75% IACS.

In the copper alloy for electronic and electrical equipment according to the present embodiment, the 0.2% proof stress in the tensile test in the direction parallel to the rolling direction is preferably in the range of 200MPa to 450 MPa. That is, in the present embodiment, a rolled material of a copper alloy for electronic and electrical equipment is used, and the 0.2% proof stress when a tensile test is performed in a direction parallel to the rolling direction in the final step of rolling is defined as described above.

In the copper alloy for electronic and electrical equipment according to the present embodiment, the residual stress ratio is preferably 75% or more under the conditions of 150 ℃ and 1000 hours.

The reason why the composition, crystal structure, and various properties are defined as described above will be described below.

(Mg: 0.15 mass% or more and less than 0.35 mass%)

Mg is an element having the following effects: the copper alloy is dissolved in the mother phase of the copper alloy, so that the strength and the stress relaxation resistance are improved under the condition of keeping higher conductivity.

When the Mg content is less than 0.15 mass%, the effects may not be sufficiently exhibited. On the other hand, if the Mg content is 0.35 mass% or more, the electric conductivity may be greatly reduced, and the viscosity of the copper alloy melt may be increased, resulting in a reduction in castability.

From the above, in the present embodiment, the content of Mg is set in the range of 0.15 mass% or more and less than 0.35 mass%.

In order to further improve the strength and the stress relaxation resistance, the lower limit of the Mg content is preferably 0.16 mass% or more, more preferably 0.17 mass% or more, and still more preferably 0.18 mass% or more. In order to reliably suppress the decrease in conductivity and the decrease in castability, the upper limit of the Mg content is preferably 0.32 mass% or less, more preferably 0.30 mass% or less, and still more preferably 0.28 mass% or less.

(P: 0.0005 mass% or more and less than 0.01 mass%)

P is an element having an action effect of improving castability.

When the content of P is less than 0.0005 mass%, the effects may not be sufficiently exhibited. On the other hand, if the content of P is 0.01 mass% or more, coarse crystals containing Mg and P are generated, and therefore the crystals become starting points of fracture, and there is a possibility that cracks are generated at the time of cold working or bending.

From the above, in the present embodiment, the content of P is set in the range of 0.0005 mass% or more and less than 0.01 mass%. In order to reliably improve castability, the lower limit of the content of P is preferably 0.001 mass% or more, and more preferably 0.002 mass% or more. In order to reliably suppress the generation of coarse crystals, the upper limit of the content of P is preferably less than 0.009 mass%, more preferably less than 0.008 mass%, and still more preferably 0.0075 mass% or less.

(〔Mg〕+20×〔P〕＜0.5)

As described above, Mg and P coexist, and thus a crystal including Mg and P is generated.

Here, when the content of Mg is [ Mg ] and the content of P is [ P ] in terms of mass ratio, if the value of [ Mg ] +20 × [ P ] is 0.5 or more, the total amount of Mg and P is large, crystals including Mg and P are coarsened and distributed at high density, and there is a possibility that cracks are easily generated at cold working or bending working.

As described above, in the present embodiment, the value of [ Mg ] +20 × [ P ] is set to be less than 0.5. Further, in order to reliably suppress the occurrence of cracks during cold working or bending by suppressing the coarsening and densification of the crystal, the value of [ Mg ] +20 × [ P ] is preferably less than 0.48, more preferably less than 0.46.

(〔Mg〕/〔P〕≤400)

Mg is an element having an action of increasing the viscosity of the copper alloy melt and reducing the castability, and therefore, in order to reliably improve the castability, the ratio of the content of Mg to the content of P needs to be appropriate.

Here, when the content of Mg is [ Mg ] and the content of P is [ P ] in terms of mass ratio, the ratio of the content of Mg to the content of P can be made appropriate by setting the value of [ Mg ]/[ P ] to 400 or less, and the effect of improving castability by the addition of P can be reliably exhibited.

As described above, in the present embodiment, the value of [ Mg ]/[ P ] is set to 400 or less. In order to further improve castability, the value of [ Mg ]/[ P ] is preferably 350 or less, more preferably 300 or less.

If the value of [ Mg ]/[ P ] is too low, Mg is consumed as a crystal, and the effect of solid solution of Mg may not be obtained. In order to suppress the formation of crystals containing Mg and P and to reliably improve the yield strength and the stress relaxation resistance by solid solution of Mg, the lower limit of the value of [ Mg ]/[ P ] is preferably set to more than 20, more preferably more than 25.

(inevitable impurities)

Examples of the other inevitable 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, Ni, Pd, Pt, Au, Zn, Cd, Hg, Al, Ga, In, Ge, Sn, As, Sb, Tl, Pb, Bi, Be, N, C, Si, Li, H, O, and S. Since these unavoidable impurities have an effect of lowering the conductivity, it is preferable to reduce the amount of the unavoidable impurities.

In addition, Ag, Zn, and Sn are easily mixed into copper to lower the conductivity, and therefore the total amount of Ag, Zn, and Sn is preferably less than 500 mass ppm.

In addition, Si, Cr, Ti, Zr, Fe, and Co greatly reduce the electric conductivity in particular, and deteriorate the bending workability by the formation of inclusions, so it is preferable that the total amount of these elements (Si, Cr, Ti, Zr, Fe, and Co) is less than 500 mass ppm.

(ratio of grain boundary triple points)

The punching workability in press working is more excellent as the burr height at the time of fracture is smaller. Here, the relative burr height tends to be higher as the thickness of the material subjected to the press working increases.

In order to reduce the burr height during press working, it is sufficient to rapidly cause fracture along the grain boundary during press working. If the network of random grain boundaries becomes long, fracture along the grain boundaries tends to occur. In order to extend the network length of random grain boundaries, it is important to control the proportion of J3 of a special grain boundary having all grain boundaries equal to or smaller than Σ 29 among three grain boundaries constituting the grain boundary triple point, or the proportion of J2 of two grain boundaries among the three grain boundaries which are special grain boundaries.

Therefore, in the present embodiment, 0.20 < (NF) is satisfied_J2/(1-NF_J3))^0.5≤0.45。

The surface perpendicular to the width direction of rolling was used as an observation surface, and 10000 μm was measured at a measurement interval of 0.25 μm for the parent phase by the EBSD method²The above measurement area. Next, measurement points having CI values of 0.1 or less analyzed by the data analysis software OIM were removed and analyzed, and a grain boundary was defined between measurement points where the difference in orientation between adjacent measurement points exceeded 15 °. The corresponding grain boundaries below Σ 29 are special grain boundaries, and the other grain boundaries are random grain boundaries. In the grain boundary triple point by the OIM analysis, all three grain boundaries constituting the grain boundary triple point are specifiedThe proportion of J3 with very grain boundaries to all grain boundary triple points is set as NF_J3The ratio of J2 in which two grain boundaries constituting grain boundary triple points are special grain boundaries and one grain boundary is random grain boundaries to all the grain boundary triple points is NF_J2. These NF_J3And NF_J2The following relationship is satisfied,

0.20＜(NF_J2/(1-NF_J3))^0.5≤0.45。

herein, if (NF)_J2/(1-NF_J3))^0.5When the value of (2) exceeds 0.45, the network length of random grain boundaries becomes relatively short, and the network length of special grain boundaries becomes long. Therefore, the burr height during press working becomes high. On the other hand, (NF)_J2/(1-NF_J3))^0.5When the value of (d) is 0.20 or less, the bending workability is lowered because the worked structure is substantially formed. Thus, in this embodiment, (NF) is_J2/(1-NF_J3))^0.5The value of (b) is in the range of more than 0.20 and 0.45 or less.

In addition, (NF)_J2/(1-NF_J3))^0.5The lower limit of the value of (b) is preferably 0.21 or more, more preferably 0.22 or more, and further preferably 0.23 or more. On the other hand, (NF)_J2/(1-NF_J3))^0.5The upper limit of the value of (b) is preferably 0.40 or less, more preferably 0.35 or less.

(conductivity: more than 75% IACS)

In the copper alloy for electronic/electric devices according to the present embodiment, when the electrical conductivity is set to exceed 75% IACS, the copper alloy can be suitably used as a component for electronic/electric devices such as a terminal and a bus bar of a connector or a pressure-bonded body.

The conductivity is preferably more than 76% IACS, more preferably more than 77% IACS, and still more preferably more than 78% IACS.

(0.2% yield strength: 200MPa or more and 450MPa or less)

The copper alloy for electronic/electrical equipment according to the present embodiment is particularly suitable as a material for electronic/electrical equipment components such as terminals and busbars such as connectors and pressure-sensitive adhesives, by having a 0.2% proof stress of 200MPa or more. In the present embodiment, the 0.2% proof stress in the tensile test conducted in the direction parallel to the rolling direction is 200MPa or more. When terminals such as connectors and laminates, busbars, and the like are manufactured by pressing, a strip material wound into a coil is used to improve productivity, but if the 0.2% proof stress exceeds 450MPa, a coil is formed, and productivity is lowered. Therefore, the 0.2% yield strength is preferably 450MPa or less.

The lower limit of the 0.2% yield strength is preferably 220MPa or more, and more preferably 250MPa or more. The upper limit of the 0.2% yield strength is preferably 420MPa or less, more preferably 400MPa or less, still more preferably 380MPa or less, and most preferably 350MPa or less.

(residual stress ratio: 75% or more)

In the copper alloy for electronic and electrical equipment of the present embodiment, the residual stress ratio is set to 75% or more under the conditions of 150 ℃ and 1000 hours, as described above.

When the residual stress ratio under such conditions is high, the permanent strain can be controlled to be small even when used in a high-temperature environment, and the decrease in contact pressure can be suppressed. Therefore, the copper alloy for electronic and electrical equipment according to the present embodiment can be suitably used as a terminal used in a high-temperature environment such as around an engine room of an automobile. In the present embodiment, the residual stress ratio in the stress relaxation test performed in the direction parallel to the rolling direction is set to 75% or more under the conditions of 150 ℃ and 1000 hours.

The residual stress ratio is preferably 77% or more under the conditions of 150 ℃ and 1000 hours, and more preferably 80% or more under the conditions of 150 ℃ and 1000 hours.

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

(melting and casting step S01)

First, the above elements are added to a copper melt obtained by melting a copper raw material to adjust the composition, thereby producing a copper alloy melt. In addition, for addition of various elements, an element sheet can be usedA prime or master alloy, and the like. Further, the raw material containing the above-mentioned elements may be melted together with the copper raw material. Furthermore, recycled materials and scraps of the alloy (the copper alloy of the present embodiment) may also be used. Here, the molten copper is preferably so-called 4NCu having a purity of 99.99 mass% or more, or so-called 5NCu having a purity of 99.999 mass% or more. In the melting step, it is preferable that H is added to suppress the oxidation of Mg and to reduce the hydrogen concentration₂The melting is performed in an inert gas atmosphere (e.g., Ar gas) having a low vapor pressure of O, and the holding time during the melting is minimized.

Then, the copper alloy melt adjusted in composition is poured into a mold to form an ingot. In addition, in view of mass production, it is preferable to use a continuous casting method or a semi-continuous casting method.

In this case, since a crystal including Mg and P is formed when the melt solidifies, the crystal size can be made finer by increasing the solidification speed. Therefore, the cooling rate of the melt is preferably 0.1 ℃/sec or more, more preferably 0.5 ℃/sec or more.

(homogenizing step S02)

Next, the obtained ingot is subjected to a heat treatment for homogenization. In some cases, an intermetallic compound containing Cu and Mg as main components, which is generated by segregation and concentration of Mg during solidification, exists inside the ingot.

Therefore, in order to eliminate or reduce these segregation and intermetallic compounds, a heating treatment of heating the ingot to 300 ℃ or more and 900 ℃ or less is performed. This causes Mg to be uniformly diffused into the ingot or causes Mg to be dissolved in the matrix phase. The homogenization step S02 is preferably performed in a non-oxidizing or reducing atmosphere.

(Hot working Process S03)

Since Mg segregation is likely to occur in the grain boundary, if Mg segregation is present, it is difficult to control the grain boundary triple point.

Therefore, in order to thoroughly homogenize the structure, the homogenization step S02 is followed by hot working. The total reduction ratio in hot working is preferably 50% or more, more preferably 60% or more, and still more preferably 70% or more. The processing method in the hot working step S03 is not particularly limited, and rolling, drawing, extrusion, groove rolling, forging, pressing, or the like can be used, for example. The hot working temperature is preferably in the range of 400 ℃ to 900 ℃.

(solutionizing step S04)

In order to completely eliminate Mg segregation in the grain boundaries, a solution heat treatment is performed after the hot working step S03. The conditions of the solutionizing step S04 are preferably such that the heating temperature is in the range of 500 ℃ to 900 ℃ inclusive, and the holding time at the heating temperature is in the range of 1 second to 10 hours inclusive. The solutionizing step S04 may be performed as the hot working step S03. In this case, the temperature at the end of the hot working may be set to be higher than 500 ℃, and the steel sheet may be kept at a temperature of 500 ℃ or higher for 10 seconds or longer after the end of the hot working.

Here, when the heating temperature is less than 500 ℃, the solutionizing is incomplete, and a large amount of intermetallic compounds containing Cu and Mg as main components may remain in the matrix phase. On the other hand, if the heating temperature exceeds 900 ℃, part of the copper raw material becomes a liquid phase, and the texture and surface state may be uneven. Therefore, the heating temperature is set in the range of 500 ℃ to 900 ℃.

(crude processing step S05)

Rough machining is performed to form a predetermined shape. In the rough processing step S05, warm processing at 100 to 350 ℃ is performed at least once. By performing warm working at 100 ℃ to 350 ℃, it is possible to increase the size of the extremely small recrystallized region during the working, randomize the structure at the time of recrystallization in the intermediate heat treatment step S06, which is a subsequent step, and increase the total number of random grain boundaries. When warm working is performed once, it is performed in the final step of the rough working step S05. In addition, instead of warm working, heat generated by working by increasing the working rate in each working step may be used. In this case, for example, the rolling is preferably performed with a reduction ratio per pass of 15% or more, preferably 20% or more, and more preferably 30% or more. The warm working is preferably performed twice or more. The temperature for warm working is preferably 150 ℃ to 350 ℃, and more preferably more than 200 ℃ to 350 ℃.

(intermediate Heat treatment Process S06)

After the rough machining step S05, heat treatment is performed for the purpose of recrystallization texturing to increase the number ratio of random grain boundaries and softening to improve workability. The method of heat treatment is not particularly limited, but heat treatment is preferably performed in a non-oxidizing atmosphere or a reducing atmosphere at a holding temperature of 400 ℃ to 900 ℃ inclusive and a holding time of 10 seconds to 10 hours inclusive. Further, the cooling method after heating is not particularly limited, but a method of setting a cooling rate to 200 ℃/min or more such as water quenching is preferably employed.

Further, the rough processing step S05 and the intermediate heat treatment step S06 may be repeatedly performed.

(finishing step S07)

The copper material after the intermediate heat treatment step S06 is finished to be worked into a predetermined shape. In the finishing step S07, warm working at 50 ℃ or more and less than 300 ℃ is performed at least once in order to improve the stress relaxation resistance. By performing warm working at 50 ℃ or higher and less than 300 ℃, the dislocations introduced during the working are rearranged, and thus the stress relaxation resistance is improved. The finishing step S07 differs in the processing method and the processing rate depending on the final shape, but rolling may be performed when a bar or a plate is produced. In addition, the steps other than the warm working at least once may be ordinary cold working. Instead of warm working at 50 ℃ or higher and less than 300 ℃, heat generation by working can be utilized by increasing the working ratio in each working step. In this case, for example, in the rolling, the reduction ratio per pass may be set to 10% or more.

Further, although the working ratio is appropriately selected so as to approach the final shape, in order to set the tensile strength between 200MPa and 450MPa by work hardening in the finishing step S07, the upper limit of the working ratio is preferably 75% or less, more preferably 65% or less, further preferably 60% or less, and most preferably less than 40%.

(Final Heat treatment Process S08)

Next, the plastic worked material obtained in the finishing step S07 is subjected to a final heat treatment for the purpose of improving the stress relaxation resistance and the hardening due to low-temperature annealing, or for the purpose of removing residual strain. The heat treatment temperature is preferably in the range of 100 ℃ to 800 ℃. In the final heat treatment step S08, in order to suppress the number ratio of the special grain boundaries to the grain boundary triple points by recrystallization, it is necessary to set heat treatment conditions (temperature, time, and cooling rate).

For example, the holding time is preferably set to 10 seconds or more and 10 hours or less in the range from 200 ℃ to 300 ℃. The heat treatment is preferably performed in a non-oxidizing atmosphere or a reducing atmosphere. The method of heat treatment is not particularly limited, but heat treatment at high temperature for a short time by a continuous annealing furnace is preferable from the viewpoint of the effect of reducing the production cost.

The finishing step S07 and the final heat treatment step S08 may be repeatedly performed.

The copper alloy for electronic and electrical equipment (copper alloy strip for electronic and electrical equipment) of the present embodiment is produced in this manner. The upper limit of the thickness of the copper alloy strip for electrical and electronic equipment is not particularly limited, but when the copper alloy strip for electrical and electronic equipment is formed into a connector, a terminal, and a bus bar by press working, if the thickness exceeds 5.0mm, the load of the press machine is significantly increased, and the productivity per unit time is lowered, thereby increasing the cost. Therefore, in the present embodiment, it is preferable that the thickness of the copper alloy strip for electronic and electrical equipment is more than 0.5mm and 5.0mm or less. The lower limit of the thickness of the copper alloy strip for electronic and electrical equipment is preferably more than 1.0mm, and more preferably more than 3.0 mm.

Here, the copper alloy strip for electronic and electrical equipment of the present embodiment can be used as it is for components for electronic and electrical equipment, but a tin-plated layer or a silver-plated layer having a film thickness of about 0.1 to 100 μm may be formed on one surface or both surfaces of the plate surface.

Further, the copper alloy for electronic and electrical equipment (copper alloy plate bar for electronic and electrical equipment) of the present embodiment is used as a raw material, and punching, bending, or the like is performed to mold a module for electronic and electrical equipment, such as a terminal, a bus bar, or the like of a connector, a pressure-bonded body, or the like.

According to the copper alloy for electronic and electrical equipment having the above-described configuration, since the content of Mg is set to be in the range of 0.15 mass% or more and less than 0.35 mass%, Mg is dissolved in the matrix phase of copper, so that the strength and the stress relaxation resistance can be improved without significantly lowering the electrical conductivity.

Further, since P is contained in a range of 0.0005 mass% or more and less than 0.01 mass%, castability can be improved.

Further, since the content [ Mg ] of Mg and the content [ P ] of P satisfy the relationship of [ Mg ] +20 × [ P ] < 0.5 in terms of mass ratio, the formation of coarse crystals of Mg and P can be suppressed, and the reduction of cold workability and bending workability can be suppressed.

In addition, in the present embodiment, since the content [ Mg ] of Mg and the content [ P ] of P satisfy the relationship of [ Mg ]/[ P ] of not more than 400 in terms of mass ratio, the ratio of the content of Mg that decreases the castability to the content of P that increases the castability can be made appropriate, and the castability can be reliably improved by the effect of the addition of P.

Then, 10000 μm were measured at a measurement interval of 0.25 μm for the parent phase by the EBSD method using a plane orthogonal to the width direction of rolling as an observation plane²The above measurement area. Next, measurement points having CI values of 0.1 or less analyzed by the data analysis software OIM were removed and analyzed, and a grain boundary was defined between measurement points where the difference in orientation between adjacent measurement points exceeded 15 °. The corresponding grain boundaries below Σ 29 are special grain boundaries, and the other grain boundaries are random grain boundaries. In the grain boundary triple points by the OIM analysis, the ratio of J3, in which all three grain boundaries constituting the grain boundary triple points are special grain boundaries, to all the grain boundary triple points was NF_J3The ratio of J2 in which two grain boundaries constituting grain boundary triple points are special grain boundaries and one grain boundary is random grain boundaries to all the grain boundary triple points is NF_J2. For these NF_J3And NF_J2，0.20＜(NF_J2/(1-NF_J3))^0.5Not more than 0.45, so the random grain boundary network length is long, the press processing rapidly along the grain boundary damage, therefore the punching processability is also excellent.

In the copper alloy for electronic and electrical equipment according to the present embodiment, the 0.2% proof stress in the tensile test in the direction parallel to the rolling direction is 200MPa or more and 450MPa or less, and the electrical conductivity is more than 75% IACS. Therefore, the copper alloy for electronic/electrical equipment according to the present embodiment is suitable for use in electronic/electrical equipment components that are thickened in accordance with the use of high voltage and large current, and is particularly suitable for use as a material for electronic/electrical equipment components such as terminals and bus bars, such as connectors and pressure-bonded bodies.

In the copper alloy for electronic and electrical equipment according to the present embodiment, the residual stress ratio is 75% or more under the conditions of 150 ℃ and 1000 hours. Therefore, even when used in a high-temperature environment, the permanent deformation can be suppressed to a small level, and a decrease in contact pressure of, for example, a connector terminal or the like can be suppressed. Therefore, the copper alloy for electronic and electrical equipment according to the present embodiment can be suitably used as a material for electronic equipment components used in a high-temperature environment such as an engine room.

The copper alloy strip for electrical and electronic equipment according to the present embodiment is made of the above copper alloy for electrical and electronic equipment. Therefore, by bending the copper alloy sheet for electrical and electronic equipment, it is possible to manufacture a module for electrical and electronic equipment such as a terminal and a bus bar of a connector or a pressure-bonded body.

In addition, when the tin-plated layer or the silver-plated layer is formed on the surface, the copper alloy sheet bar for electronic/electrical equipment according to the present embodiment is particularly suitable as a material for a component for electronic/electrical equipment such as a terminal and a bus bar of a connector or a laminate.

Further, since the electronic/electrical device module (the terminal such as the connector or the pressure-bonded body, the bus bar, and the like) of the present embodiment is made of the above-described copper alloy for electronic/electrical devices, the electronic/electrical device module can exhibit excellent characteristics even if the electronic/electrical device module is made large or thick.

The above description has been made of the copper alloy for electronic and electrical equipment, the copper alloy plate bar for electronic and electrical equipment, and the module for electronic and electrical equipment (terminal, bus bar, etc.) according to the embodiments of the present invention, but the present invention is not limited thereto, and modifications can be made as appropriate within the scope not departing from the technical requirements of the present invention.

For example, although the above embodiment describes an example of the method for producing a copper alloy for electronic and electrical devices, the method for producing a copper alloy for electronic and electrical devices is not limited to the method described in the embodiment, and a conventional production method may be appropriately selected and produced.