JP2019173093A - Copper alloy for electronic and electric device, copper alloy thin sheet for electronic and electric device, conductive component and terminal for electronic and electric device - Google Patents

Abstract

To provide a copper alloy for electronic and electric device surely and sufficiently excellent in stress relaxation resistance and excellent in strength, stress corrosion crack resistance, and flexure processability.SOLUTION: An alloy contains specified amounts of Zn, Sn, Ni, Fe, and P, and the balance Cu with inevitable impurities, has Fe/Ni and (Ni+Fe)/P, Sn/(Ni+Fe) satisfying prescribed formulae, and has area percentage of a crystal particle having an aspect ratio b/a represented by major length a and minor length b of crystal particle diameter (including twin crystal) of 0.1 or less of 40% or more of measured whole area by Area fraction, when measured area of 200 μmor more by EBSD method with measurement interval of 0.03 μm steps and analyzed with excluding a measurement point with CI value of 0.1 or less analyzed by data analysis software OIM in a base phase containing Cu, Zn and Sn with a face orthogonal to a width direction of rolling as an observation face, with 0.2% yield stress of 500 MPa or more and less than 650 MPa.SELECTED DRAWING: None

Description

  The present invention is for a Cu-Zn-Sn based electronic / electrical device used as a conductive part for electronic / electrical devices such as a connector of a semiconductor device, other terminals, or a movable conductive piece of an electromagnetic relay, or a lead frame. The present invention relates to a copper alloy, a copper alloy thin plate for electronic / electric equipment, a conductive component for electronic / electric equipment, and a terminal using the copper alloy.

From the viewpoints of strength, workability, cost balance, etc., Cu—Zn alloys have been widely used as the above-mentioned electronic / electrical conductive parts.
In addition, in the case of terminals such as connectors, in order to increase the reliability of contact with the conductive member on the other side, the surface of the base material (base plate) made of a Cu—Zn alloy should be used with tin (Sn) plating. There is. Cu-Zn-Sn alloys are used for conductive parts such as connectors with a Cu-Zn alloy as the base material and Sn plating on the surface, in order to improve the recyclability of Sn plating materials and improve the strength. There is a case.

  Here, for example, conductive parts for electronic and electrical equipment such as connectors are generally formed into a predetermined shape by punching a thin plate (rolled plate) having a thickness of about 0.05 to 1.0 mm, and at least a part thereof. It is manufactured by bending. In this case, it is used to contact the mating conductive member near the bent portion to obtain an electrical connection with the mating conductive member, and to maintain the contact state with the mating conductive material by the spring property of the bent portion. .

  It is desired that the copper alloy for electronic / electric equipment used in such an electronic / electric equipment conductive component is excellent in conductivity, rollability and punching workability. Furthermore, as described above, bending workability is applied in the case of a connector used to maintain the contact state with the mating conductive material in the vicinity of the bent portion due to the bending property of the bent portion. It is required that the stress relaxation resistance is excellent.

Therefore, for example, Patent Documents 1 to 3 propose a method for improving the stress relaxation resistance of the Cu—Zn—Sn alloy.
In Patent Document 1, it is said that the stress relaxation resistance can be improved by adding Ni to a Cu—Zn—Sn alloy to produce a Ni—P compound, and the addition of Fe is also stress relaxation resistance. It has been shown to be effective in improving the characteristics.
Patent Document 2 describes that the strength, elasticity, and heat resistance can be improved by adding Ni and Fe together with P to a Cu—Zn—Sn-based alloy to form a compound. Improvement of strength, elasticity, and heat resistance means improvement of stress relaxation resistance.

Patent Document 3 describes that the stress relaxation resistance can be improved by adding Ni to the Cu-Zn-Sn alloy and adjusting the Ni / Sn ratio within a specific range. Further, it is described that the addition of a small amount of Fe is effective in improving the stress relaxation resistance.
Furthermore, in Patent Document 4 for lead frame materials, Ni and Fe are added to a Cu—Zn—Sn alloy together with P, and the atomic ratio of (Fe + Ni) / P is within a range of 0.2 to 3. It is described that the stress relaxation resistance can be improved by adjusting to the above and generating Fe-P compounds, Ni-P compounds, and Fe-Ni-P compounds.

In addition, in the above-mentioned conductive parts for electronic and electrical equipment, there is a risk of stress corrosion cracking depending on the usage environment. Therefore, the copper alloy for electronic and electrical equipment used for conductive parts for electronic and electrical equipment is used. May require improved stress corrosion cracking resistance.
Thus, for example, Patent Documents 5 and 6 propose methods for improving the stress corrosion cracking resistance of Cu—Zn—Sn alloys.
Patent Document 5 describes that the stress corrosion cracking resistance is improved by adjusting the crystal grain size of the Cu—Zn—Sn alloy.
Patent Document 6 describes that the stress corrosion cracking resistance can be improved by adding Ni and Si to a Cu-Zn alloy.

JP 05-33087 A JP 2006-283060 A Japanese Patent No. 3953357 Japanese Patent No. 3717321 JP 2007-056365 A JP 2007-182615 A

However, in Patent Documents 1 and 2, only the individual contents of Ni, Fe, and P are considered, and the adjustment of such individual contents does not necessarily ensure the stress relaxation resistance. Could not be improved.
Patent Document 3 discloses that the Ni / Sn ratio is adjusted, but the relationship between the P compound and the stress relaxation resistance is not considered at all, and sufficient and reliable stress relaxation resistance is obtained. It was not possible to improve.
Furthermore, in Patent Document 4, only the total amount of Fe, Ni, and P and the atomic ratio of (Fe + Ni) / P were adjusted, and the stress relaxation resistance could not be sufficiently improved.

In Patent Document 5, although the stress corrosion cracking resistance is improved by adjusting the crystal grain size, the stress relaxation resistance is lower than phosphor bronze (C5210) and is insufficient.
In Patent Document 6, although stress corrosion cracking resistance is improved by adding Ni or Si, the stress relaxation resistance is not considered.

As described above, the conventionally proposed methods cannot sufficiently improve the stress relaxation resistance of the Cu—Zn—Sn alloy. For this reason, in the connector having the above-described structure, the residual stress is relaxed over time or in a high-temperature environment, and the contact pressure with the counterpart conductive member is not maintained, and inconveniences such as poor contact are likely to occur at an early stage. There was a problem.
Furthermore, stress corrosion cracking may occur depending on the use environment, which may make it difficult to use. In order to avoid such a problem, conventionally, the thickness of the material has to be increased, leading to an increase in material cost and weight. In addition, expensive phosphor bronze is sometimes used.
Therefore, in the above-described Cu—Zn—Sn-based alloy, there is a strong demand for further reliable and sufficient improvement of the stress relaxation resistance and improvement of the stress corrosion cracking resistance.

  The present invention has been made in the background as described above, and is an electronic / electrical device that has excellent and sufficient stress relaxation resistance as well as strength, stress corrosion cracking resistance, and bending workability. It is an object of the present invention to provide a copper alloy for copper, a copper alloy thin plate for electronic / electric equipment, a conductive component for electronic / electric equipment and a terminal using the copper alloy.

In order to solve the above-mentioned problems, the present inventors have conducted extensive experiments and researches. As a result, an appropriate amount of Ni and Fe and an appropriate amount of P are added to a Cu—Zn—Sn alloy, and Fe and Ni are added. Fe / Ni ratio, Ni / Fe total content (Ni + Fe) and P content (Ni + Fe) / P, Sn content, Ni and Fe total content (Ni + Fe) By adjusting the ratio Sn / (Ni + Fe) to an appropriate range in terms of atomic ratio, precipitates containing Fe, Ni, and P are appropriately precipitated, and at the same time, the crystal grain size of the base material It was found that by appropriately adjusting the aspect ratio, the stress relaxation resistance can be reliably and sufficiently improved, and at the same time, the strength is excellent and the stress corrosion cracking resistance can be improved.
Furthermore, it has been found that the stress relaxation resistance and strength can be further improved by adding an appropriate amount of Co simultaneously with Ni, Fe and P described above.

The present invention has been made on the basis of the above-mentioned knowledge, and the copper alloy for electronic / electric equipment according to the present invention has Zn exceeding 7 mass% and less than 13 mass%, Sn being 0.1 mass% or more and 0.9 mass%. % Or less, Ni containing 0.05 mass% or more and less than 1.0 mass%, Fe containing 0.001 mass% or more and less than 0.10 mass%, P containing 0.005 mass% or more and 0.1 mass% or less, and the balance being Cu and inevitable It is made of impurities, and the ratio Fe / Ni between the Fe content and the Ni content satisfies an atomic ratio of 0.002 ≦ Fe / Ni <1.5, and the total content of Ni and Fe (Ni + Fe ) And the content of P (Ni + Fe) / P satisfy an atomic ratio of 3 <(Ni + Fe) / P <15, and the Sn content and the total amount of Ni and Fe (Ni + F) ) And Sn / (Ni + Fe) in terms of atomic ratio satisfy 0.3 <Sn / (Ni + Fe) <5, and a plane orthogonal to the width direction of rolling is an observation plane, Cu, Zn and Sn The measurement phase of 200 μm ² or more is measured at a measurement interval of 0.03 μm step by EBSD method, except for the measurement points where the CI value analyzed by the data analysis software OIM is 0.1 or less. When analyzed, the area ratio of crystal grains in which the aspect ratio b / a represented by the major axis a and the minor axis b of the crystal grain size (including twins) is 0.1 or less is the area measured by Area fraction. It is characterized by being 40% or more of the whole and 0.2% proof stress being 500 MPa or more and less than 650 MPa.

According to the copper alloy for electronic / electric equipment having the above-described configuration, Ni and Fe are added together with P, and are precipitated from the parent phase by regulating the addition ratio among Sn, Ni, Fe, and P. [Ni, Fe] -P-based precipitates containing Fe, Ni, and P are appropriately present, and at the same time, the area ratio of the crystal grains in which the aspect ratio of the crystal grains of the parent phase is 0.1 or less is represented by Area. Since the fraction is 40% or more of the entire measured area, the stress relaxation resistance is surely and sufficiently excellent, the strength (proof stress) is high, and the stress corrosion cracking resistance is also excellent.
Here, the [Ni, Fe] -P-based precipitates are Ni—Fe—P ternary precipitates, or Fe—P or Ni—P binary precipitates. In some cases, a multi-component precipitate containing, for example, Cu, Zn, Sn as main components, O, S, C, Co, Cr, Mo, Mn, Mg, Zr, Ti, or the like as impurities is included. The [Ni, Fe] -P-based precipitates exist in the form of phosphides or alloys in which phosphorus is dissolved.

  The EBSD method means an electron beam diffraction diffraction pattern (EBSD) method using a scanning electron microscope equipped with a backscattered electron diffraction image system, and OIM is a crystal using the measurement data obtained by EBSD. Data analysis software Orienting Imaging Microscopy (OIM) for analyzing the orientation. Furthermore, the CI value is a reliability index (Confidence Index), which is displayed as a numerical value representing the reliability of crystal orientation determination when analyzed using the analysis software OIM Analysis (Ver. 7.1) of the EBSD device. (For example, “EBSD Reader: Using OIM (Revised 3rd Edition)” written by Seiichi Suzuki, September 2009, published by TSL Solutions, Inc.). Here, when the structure of the measurement point measured by EBSD and analyzed by OIM is a processed structure, since the crystal pattern is not clear, the reliability of crystal orientation determination is lowered, and the CI value is lowered. In particular, when the CI value is 0.1 or less, it is determined that the structure of the measurement point is a processed structure.

  Furthermore, in the present invention, since the 0.2% proof stress is adjusted to 500 MPa or more and less than 650 MPa, the strength is high and the bending workability is excellent. Therefore, various shapes of conductive parts for electronic and electrical equipment can be formed by bending.

The copper alloy for electronic / electrical equipment according to another aspect of the present invention is more than 7 mass% and less than 13 mass%, Sn is 0.1 mass% to 0.9 mass%, Ni is 0.05 mass% to 1.0 mass%. Fe, 0.001 mass% or more and less than 0.10 mass%, Co containing 0.001 mass% or more and less than 0.1 mass%, P containing 0.005 mass% or more and 0.1 mass% or less, the balance being Cu and inevitable impurities The ratio of the total content of Fe and Co to the content of Ni (Fe + Co) / Ni satisfies the atomic ratio of 0.002 ≦ (Fe + Co) / Ni <1.5, and Ni, Fe and The ratio (Ni + Fe + Co) / P of the total Co content (Ni + Fe + Co) to the P content is 3 <(Ni + Fe + Co) / P <15 in atomic ratio. However, the ratio Sn / (Ni + Fe + Co) between the Sn content and the total content of Ni, Fe and Co (Ni + Fe + Co) satisfies an atomic ratio of 0.3 <Sn / (Ni + Fe + Co) <5. A data analysis software for measuring a measurement area of 200 μm ² or more with a measurement interval of 0.03 μm step by EBSD method on a parent phase containing Cu, Zn and Sn with a plane orthogonal to the width direction of When the analysis is performed excluding the measurement points where the CI value analyzed by OIM is 0.1 or less, the aspect ratio b / a represented by the major axis a and the minor axis b of the crystal grain size (including twins) is 0. The area ratio of crystal grains that is less than or equal to 1 is 40% or more of the total area measured by Area fraction, and the 0.2% proof stress is 500 MPa or more and less than 650 MPa. It is characterized by a door.

According to the copper alloy for electronic and electrical equipment having the above-described configuration, by adding Ni, Fe and Co together with P, and appropriately regulating the addition ratio among Sn, Ni, Fe, Co and P, [Ni, Fe, Co] -P-based precipitates containing Fe, Ni, Co, and P precipitated from the mother phase are appropriately present, and the aspect ratio of the mother phase crystal grains is 0.1 or less. The area ratio of the crystal grains is 40% or more of the total area measured by the area fraction. Therefore, the stress relaxation resistance is reliable and sufficiently excellent, and the strength (proof stress) is high, and it is resistant to stress corrosion cracking. Also excellent.
Here, the [Ni, Fe, Co] -P-based precipitates are Ni—Fe—Co—P quaternary precipitates, or Ni—Fe—P, Ni—Co—P, or Fe—Co. -P ternary precipitates, or Fe-P, Ni-P, or Co-P binary precipitates, and other elements such as Cu, Zn, Sn, impurities It may contain multi-component precipitates containing O, S, C, Cr, Mo, Mn, Mg, Zr, Ti and the like. The [Ni, Fe, Co] -P-based precipitates exist in the form of phosphides or alloys in which phosphorus is dissolved.

  Furthermore, in the present invention, since the 0.2% proof stress is adjusted to 500 MPa or more and less than 650 MPa, the strength is high and the bending workability is excellent. Therefore, various shapes of conductive parts for electronic and electrical equipment can be formed by bending.

Moreover, in the copper alloy for electronic / electrical equipment of the present invention, it is preferable that no crack occurs even when a W-shaped bending test is performed using a W-shaped jig having a bending radius of 0 mm.
According to the copper alloy for electronic / electrical equipment having such bending workability, it is possible to form various shapes of conductive parts for electronic / electrical equipment by bending.

The copper alloy thin plate for electronic / electric equipment of the present invention is made of the above-mentioned rolled material of copper alloy for electronic / electric equipment, and has a thickness in the range of 0.05 mm or more and 1.0 mm or less.
The copper alloy thin plate for electronic / electric equipment having such a configuration can be suitably used for connectors, other terminals, movable conductive pieces of electromagnetic relays, lead frames, and the like.

Here, in the copper alloy thin plate for electronic / electrical equipment of the present invention, Sn plating may be applied to the surface.
In this case, the base material of the Sn plating is composed of a Cu—Zn—Sn alloy containing 0.1 mass% or more and 0.9 mass% or less of Sn. It can be recovered as a scrap of Cu—Zn alloy to ensure good recyclability.

The conductive component for electronic / electric equipment of the present invention is characterized by comprising the above-described copper alloy for electronic / electric equipment.
The terminal of the present invention is characterized by comprising the above-described copper alloy for electronic / electric equipment.
Furthermore, the conductive component for electronic / electrical equipment of the present invention is characterized by comprising the above-described copper alloy thin plate for electronic / electrical equipment.
The terminal of the present invention is characterized by comprising the above-described copper alloy thin plate for electronic / electrical equipment.

  According to the conductive parts and terminals for electronic and electrical equipment having these configurations, since the stress relaxation resistance and stress corrosion cracking resistance are particularly excellent, the residual stress is less likely to be relaxed over time or in a high temperature environment. Furthermore, since stress corrosion cracking in a wet environment is also suppressed, the contact pressure with the counterpart conductive member can be maintained. Moreover, it is excellent in strength and electrical conductivity, and it is possible to reduce the thickness of conductive parts and terminals for electronic and electrical equipment. Furthermore, since it is excellent in bending workability, it can be formed into various shapes.

  According to the present invention, a copper alloy for electronic / electric equipment having excellent stress relaxation resistance and sufficient strength and strength, stress corrosion cracking resistance, bending workability, and electronic / electric equipment using the same It is possible to provide a copper alloy thin plate, a conductive component for electronic / electrical equipment, and a terminal.

It is a flowchart which shows the process example of the manufacturing method of the copper alloy for electronic and electric apparatuses of this invention.

Below, the copper alloy for electronic and electric apparatuses which is one Embodiment of this invention is demonstrated.
The copper alloy for electronic and electrical equipment according to the present embodiment is more than 7 mass% Zn and less than 13 mass%, Sn is 0.1 mass% or more and 0.9 mass% or less, Ni is 0.05 mass% or more and less than 1.0 mass%, Fe is contained in an amount of 0.001 mass% to less than 0.10 mass%, P is contained in an amount of 0.005 mass% to 0.1 mass%, and the balance is composed of Cu and inevitable impurities.

And as content ratio between each alloy element, ratio Fe / Ni of content of Fe and content of Ni is atomic ratio, following (1) Formula 0.002 <= Fe / Ni <1 .5 (1)
And the ratio of the total content of Ni and Fe (Ni + Fe) to the content of P (Ni + Fe) / P is an atomic ratio expressed by the following formula (2) 3 <(Ni + Fe) / P <15 (2)
Further, the ratio Sn / (Ni + Fe) between the Sn content, the Ni content and the total Fe content (Ni + Fe) is an atomic ratio, and the following equation (3): 0.3 <Sn / (Ni + Fe) <5 (3)
It is determined to satisfy.

Furthermore, the copper alloy for electronic / electrical equipment which is this embodiment contains Co in the range of 0.001 mass% or more and less than 0.10 mass% in addition to the above Zn, Sn, Ni, Fe, P. Also good.
The ratio of the total content of Fe and Co to the content of Ni (Fe + Co) / Ni is the atomic ratio as the content ratio between the alloy elements. ≦ (Fe + Co) / Ni <1.5 (1 ′)
Further, the ratio (Ni + Fe + Co) / P of the total content of Ni, Fe and Co (Ni + Fe + Co) to the content of P is an atomic ratio, and the following (2 ′) formula 3 <(Ni + Fe + Co) / P < 15 ... (2 ')
Further, the ratio Sn / (Ni + Fe + Co) of the Sn content and the total content of Ni, Fe and Co (Ni + Fe + Co) is expressed by the following formula (3 ′): 0.3 <Sn / (Ni + Fe + Co) ) <5 ... (3 ')
It is determined to satisfy.

  Furthermore, in the copper alloy for electronic / electrical equipment which is this embodiment, Preferably, content of S is restrict | limited to less than 20 massppm.

  Here, the reason for defining the component composition as described above will be described below.

(Zn: more than 7 mass% and less than 13 mass%)
Zn is a basic alloy element in the copper alloy which is the subject of this embodiment, and is an element effective in improving strength and springiness. Moreover, since Zn is cheaper than Cu, it is effective in reducing the material cost of the copper alloy.
Here, when the Zn content is 7 mass% or less, the effect of reducing the material cost cannot be sufficiently obtained. On the other hand, when the Zn content is 13 mass% or more, the corrosion resistance is lowered and the cold rolling property is also lowered.
Therefore, in the present embodiment, the Zn content is within the range of more than 7 mass% and less than 13 mass%.
In addition, it is preferable that the minimum of content of Zn shall be over 8 mass%. Moreover, it is preferable that the upper limit of Zn content shall be 12 mass% or less.

(Sn: 0.1 mass% or more and 0.9 mass% or less)
The addition of Sn is effective in improving the strength and is advantageous for improving the recyclability of the Cu-Zn alloy material with Sn plating. Furthermore, it has been found by the present inventors that if Sn coexists with Ni and Fe, it contributes to the improvement of stress relaxation resistance.
Here, if the Sn content is less than 0.1 mass%, these effects may not be sufficiently obtained. On the other hand, if the Sn content exceeds 0.9 mass%, the hot workability and the cold rollability are deteriorated, and there is a possibility that cracking may occur in hot rolling or cold rolling, and the electrical conductivity is also lowered. Resulting in.
Therefore, in the present embodiment, the Sn content is in the range of 0.1 mass% to 0.9 mass%.
In addition, it is preferable to set it as 0.2 mass% or more, and, as for the minimum of content of Sn, it is more preferable to set it as 0.3 mass% or more. Further, the upper limit of the Sn content is preferably 0.8 mass% or less, and more preferably 0.7 mass% or less.

(Ni: 0.05 mass% or more and less than 1.0 mass%)
When Ni is added together with Fe and P, [Ni, Fe] -P-based precipitates can be precipitated from the parent phase, and when added together with Fe, Co and P, [Ni, Fe, P Co] -P-based precipitates can be precipitated from the parent phase. The average grain size can be reduced by the effect of pinning the grain boundaries during recrystallization by these [Ni, Fe] -P-based precipitates or [Ni, Fe, Co] -P-based precipitates. Strength, bending workability, and stress corrosion cracking resistance can be improved. Furthermore, the presence of these precipitates can greatly improve the stress relaxation resistance. In addition, Ni can be improved by solid solution strengthening by coexisting with Sn, Fe, Co, and P.
Here, if the Ni content is less than 0.05 mass%, the stress relaxation resistance may not be sufficiently improved. On the other hand, if the Ni content is 1.0 mass% or more, the amount of solid solution Ni increases and the electrical conductivity decreases, and the use amount of expensive Ni raw materials increases, resulting in an increase in cost.
Therefore, in the present embodiment, the Ni content is in the range of 0.05 mass% or more and less than 1.0 mass%.
Note that the lower limit of the Ni content is preferably 0.2 mass% or more, and more preferably 0.3 mass% or more. Further, the upper limit of the Ni content is preferably less than 0.8 mass%, and more preferably 0.7 mass% or less.

(Fe: 0.001 mass% or more and less than 0.10 mass%)
Fe can be precipitated together with Ni and P to precipitate [Ni, Fe] -P-based precipitates from the parent phase, and by adding together with Ni, Co and P, [Ni, Fe, Co] -P-based precipitates can be precipitated from the parent phase. The average grain size can be reduced by the effect of pinning the grain boundaries during recrystallization by these [Ni, Fe] -P-based precipitates or [Ni, Fe, Co] -P-based precipitates. Strength, bending workability, and stress corrosion cracking resistance can be improved. Furthermore, the presence of these precipitates can greatly improve the stress relaxation resistance. Some also act as solid solution strengthening.
Here, if the Fe content is less than 0.001 mass%, the effect of pinning the crystal grain boundaries cannot be obtained sufficiently, and sufficient strength may not be obtained. On the other hand, if the Fe content is 0.10 mass% or more, no further improvement in strength is observed, the amount of solid solution Fe increases, the conductivity decreases, and the cold rolling property also decreases.
Therefore, in the present embodiment, the Fe content is set in the range of 0.001 mass% or more and less than 0.10 mass%.
The lower limit of the Fe content is preferably 0.002 mass% or more, and more preferably 0.005 mass% or more. The upper limit of the Fe content is preferably 0.08 mass% or less, more preferably 0.07 mass% or less, and even more preferably 0.04 mass% or less.

(Co: 0.001 mass% or more and less than 0.10 mass%)
Co is not necessarily an essential additive element, but if a small amount of Co is added together with Ni, Fe, and P, [Ni, Fe, Co] -P-based precipitates are generated, and the stress relaxation resistance is further improved. Can be made. For this reason, it is preferable to add suitably according to a required characteristic.
Here, if the Co content is less than 0.001 mass%, the effect of further improving the stress relaxation resistance by adding Co may not be obtained. On the other hand, if the Co content is 0.10 mass% or more, the amount of solid solution Co increases and the electrical conductivity decreases, and the use amount of expensive Co raw materials increases, resulting in an increase in cost.
Therefore, when Co is intentionally added, the Co content is set within a range of 0.001 mass% or more and less than 0.10 mass%.
In addition, it is preferable that the minimum of content of Co shall be 0.002 mass% or more. The upper limit of the Co content is preferably 0.08 mass% or less.
Even when Co is not actively added, Co of less than 0.001 mass% may be contained as an impurity.

(P: 0.005 mass% or more and 0.10 mass% or less)
P has a high bondability with Fe, Ni, and Co, and if it contains an appropriate amount of P together with Fe and Ni, a [Ni, Fe] -P-based precipitate can be precipitated. If an appropriate amount of P is contained together with Ni and Co, [Ni, Fe, Co] -P-based precipitates can be precipitated, and the stress relaxation resistance can be improved by the presence of these precipitates. . Some of them also act as solid solution strengthening, and by acting with solid solution Ni, Fe, Co, the stress relaxation resistance is improved.
Here, if the content of P is less than 0.005 mass%, it will be difficult to sufficiently precipitate [Ni, Fe] -P-based precipitates or [Ni, Fe, Co] -P-based precipitates. There is a possibility that the stress relaxation resistance cannot be improved. On the other hand, if the content of P exceeds 0.10 mass%, the amount of P solid solution increases, and the electrical conductivity is lowered and the rollability is lowered, so that cold rolling cracks are likely to occur.
Therefore, in the present embodiment, the content of P is set in the range of 0.005 mass% or more and 0.10 mass% or less.
In addition, it is preferable that the minimum of content of P shall be 0.01 mass% or more. The upper limit of the P content is preferably 0.08 mass% or less.
Note that P is an element that is inevitably mixed in from the melting material of the copper alloy. Therefore, in order to regulate the amount of P as described above, it is desirable to appropriately select the melting material.

(S: less than 20 massppm)
S reacts with Zn in each step such as melting / casting and heat treatment to generate ZnS. When ZnS is generated, residual stress tends to be generated in the vicinity of ZnS, and since it acts as a local battery, the stress corrosion cracking resistance may deteriorate.
Therefore, in order to further improve the stress corrosion cracking resistance, the S content is preferably less than 20 massppm.
The upper limit of the S content is more preferably 15 massppm or less, and more preferably 10 massppm or less. Further, the lower limit of the content of S is not particularly defined, but if it is less than 0.1 ppm, the cost is substantially increased, so 0.1 ppm or more is preferable, and 0.5 ppm or more is preferable. More preferably, it is more preferably 1 ppm or more.

  The balance of the above elements may be basically Cu and inevitable impurities. Here, inevitable impurities include Mg, Al, Mn, Si, (Co), Cr, Ag, Ca, Sr, Ba, Sc, Y, Hf, V, Nb, Ta, Mo, W, Re, Ru. , Os, Se, Te, Rh, Ir, Pd, Pt, Au, Cd, Ga, In, Li, Ge, As, Sb, Ti, Tl, Pb, Bi, (S), O, C, Be, N , H, Hg, B, Zr, rare earth, and the like. These inevitable impurities are desirably 0.1 mass% or less in total amount.

  Furthermore, in the copper alloy for electronic and electrical equipment according to the present embodiment, not only the individual addition amount ranges of the respective alloy elements are adjusted as described above, but the mutual ratio of the content of each element is an atomic ratio. It is important to regulate the ratio so as to satisfy the expressions (1) to (3) or the expressions (1 ′) to (3 ′). Therefore, the reasons for limiting the expressions (1) to (3) and (1 ′) to (3 ′) will be described below.

(1) Formula: 0.002 ≦ Fe / Ni <1.5
As a result of detailed experiments, the present inventors not only adjusted the respective contents of Fe and Ni as described above, but also their ratio Fe / Ni in terms of atomic ratio of 0.002 or more and 1 It has been found that sufficient stress relaxation resistance can be improved when it is within the range of less than .5.
Here, when Fe / Ni is 1.5 or more, the stress relaxation resistance may be lowered. When Fe / Ni is less than 0.002, the strength is lowered and the amount of expensive Ni raw material used is relatively increased, leading to an increase in cost.
Therefore, in the present embodiment, the above-mentioned Fe / Ni is regulated within the range of 0.002 or more and less than 1.5.
In addition, it is preferable that the minimum of Fe / Ni shall be 0.005 or more. Further, the upper limit of Fe / Ni is preferably 1 or less, and more preferably 0.5 or less.

(2) Formula: 3 <(Ni + Fe) / P <15
When (Ni + Fe) / P is 3 or less, the stress relaxation resistance decreases as the proportion of the solid solution P increases, and at the same time, the electrical conductivity decreases due to the solid solution P, and the rollability decreases and cold rolling is performed. Cracking is likely to occur, and bending workability may also be reduced. On the other hand, if (Ni + Fe) / P is 15 or more, the conductivity decreases due to the increase of the ratio of Ni and Fe dissolved in solid, and the amount of expensive Ni raw material used is relatively increased, leading to an increase in cost.
Therefore, in this embodiment, (Ni + Fe) / P is regulated within a range of more than 3 and less than 15.
The upper limit of (Ni + Fe) / P is preferably 12 or less.

(3) Formula: 0.3 <Sn / (Ni + Fe) <5
If Sn / (Ni + Fe) is 0.3 or less, there is a possibility that a sufficient stress relaxation resistance improving effect is not exhibited. On the other hand, when Sn / (Ni + Fe) is 5 or more, the amount of (Ni + Fe) is relatively decreased, the amount of [Ni, Fe] -P-based precipitates is decreased, and the stress relaxation resistance is deteriorated. There is a fear.
Therefore, in the present embodiment, Sn / (Ni + Fe) is regulated within the range of more than 0.3 and less than 5.
The lower limit of Sn / (Ni + Fe) is preferably more than 0.3. The upper limit of Sn / (Ni + Fe) is preferably 1.5 or less.

(1 ′) Formula: 0.002 ≦ (Fe + Co) / Ni <1.5
When Co is added, it can be considered that a part of Fe is replaced by Co, and the formula (1 ′) basically conforms to the formula (1).
Here, when (Fe + Co) / Ni is 1.5 or more, the stress relaxation resistance is lowered, and an increase in the amount of expensive Co raw material used causes an increase in cost. When (Fe + Co) / Ni is less than 0.002, the strength is lowered and the amount of expensive Ni raw material used is relatively increased, resulting in an increase in cost.
Therefore, in the present embodiment, (Fe + Co) / Ni is regulated within the range of 0.002 or more and less than 1.5.
The lower limit of (Fe + Co) / Ni is preferably 0.005 or more. Further, the upper limit of (Fe + Co) / Ni is preferably 1 or less, and more preferably 0.5 or less.

(2 ′) Formula: 3 <(Ni + Fe + Co) / P <15
The formula (2 ′) in the case of adding Co is also in accordance with the formula (2). When (Ni + Fe + Co) / P is 3 or less, the stress relaxation resistance decreases as the proportion of the solid solution P increases, and at the same time, the conductivity decreases due to the solid solution P, and the rollability decreases and cold rolling is performed. Cracking is likely to occur, and bending workability may also be reduced. On the other hand, if (Ni + Fe + Co) / P is 15 or more, the conductivity decreases due to an increase in the ratio of solid solution Ni, Fe, Co, and the amount of expensive Co and Ni raw materials used is relatively increased and the cost is increased. Invite rise.
Therefore, in the present embodiment, (Ni + Fe + Co) / P is regulated within the range of more than 3 and less than 15.
The upper limit of (Ni + Fe + Co) / P is preferably 12 or less.

(3 ′) Formula: 0.3 <Sn / (Ni + Fe + Co) <5
The formula (3 ′) in the case of adding Co is also in accordance with the formula (3). When Sn / (Ni + Fe + Co) is 0.3 or less, there is a possibility that a sufficient stress relaxation resistance improving effect is not exhibited. On the other hand, when Sn / (Ni + Fe + Co) is 5 or more, the amount of (Ni + Fe + Co) is relatively decreased, the amount of [Ni, Fe, Co] -P-based precipitates is decreased, and the stress relaxation resistance is reduced. There is a risk that.
Therefore, in the present embodiment, Sn / (Ni + Fe + Co) is regulated within the range of more than 0.3 and less than 5.
The lower limit of Sn / (Ni + Fe + Co) is preferably more than 0.3. The upper limit of Sn / (Ni + Fe + Co) is preferably 1.5 or less.

  As described above, each alloy element is adjusted not only for individual contents but also as a ratio between each element so as to satisfy the expressions (1) to (3) or (1 ′) to (3 ′). -In a copper alloy for electrical equipment, [Ni, Fe] -P-based precipitates or [Ni, Fe, Co] -P-based precipitates are dispersed and precipitated from the parent phase, and such precipitates are dispersed. Precipitation is considered to improve the stress relaxation resistance.

In addition, in the copper alloy for electronic / electric equipment which is this embodiment, as described above, [Ni, Fe] -P-based precipitates or [Ni, Fe, Co] -P-based precipitates exist. This is very important. According to the inventors' research, these precipitates have a Fe ₂ P crystal structure, that is, a hexagonal (space group: P-62m (189)) or orthorhombic (space group: P-nma). (62)). And it is desirable that these precipitates have a fine average particle diameter of 100 nm or less. Due to the presence of such fine precipitates, excellent stress relaxation characteristics can be secured, and at the same time, strength and bending workability can be improved through crystal grain refinement. Here, if the average particle size of such precipitates exceeds 100 nm, the contribution to the improvement of strength and stress relaxation resistance becomes small.

And in the copper alloy for electronic and electrical equipment which is this embodiment, the surface orthogonal to the width direction of rolling is made into an observation surface, and the parent phase containing Cu, Zn and Sn is 200 μm ² or more by EBSD method. The area of the crystal grains with an aspect ratio b / a of 0.1 or less when the major axis of the crystal grain size is a and the minor axis is b is measured at a measurement interval of 0.03 μm step. The ratio is 40% or more in the area fraction.

(aspect ratio)
By controlling the area ratio with respect to the measurement area of the crystal grains having the aspect ratio b / a of 0.1 or less to 40% or more by Area fraction, the stress corrosion cracking resistance is maintained while maintaining the stress relaxation resistance characteristics. The characteristics can be improved.
In a material subjected to rolling or the like, stress corrosion cracking generally progresses along grain boundaries in a direction perpendicular to the longitudinal direction. The major axis a of the crystal grains coincides with the longitudinal direction of the material, and the minor axis b coincides with the orthogonal direction. For this reason, when the area of the crystal grains in which the aspect ratio b / a is 0.1 or less is 40% or more in the area fraction, there are few grain boundaries along the direction perpendicular to the longitudinal direction of the material. This makes it possible to suppress stress corrosion cracking.
Here, the area ratio with respect to the measurement area of the crystal grains having the aspect ratio b / a of 0.1 or less is preferably 50% or more, and more preferably 55% or more. The upper limit is not particularly defined, but if the area ratio of the crystal grains in which the aspect ratio b / a is 0.1 or less exceeds 80% in the area fraction, the substantial rolling cost increases. It is preferable. More preferably, it is 75% or less.

Furthermore, in the copper alloy for electronic / electrical equipment which is this embodiment, 0.2% yield strength is adjusted in the range of 500 MPa or more and less than 650 MPa.
In the copper alloy for electronic / electric equipment according to this embodiment, the strength is also improved by work hardening by plastic working. When the contribution of strength by this work hardening increases, a work structure is substantially formed, so that workability such as ductility and bending workability is lowered. For this reason, by setting the 0.2% proof stress to 500 MPa or more and less than 650 MPa, the area ratio with respect to the measurement area of the crystal grain having an aspect ratio b / a of 0.1 or less is controlled to 40% or more by Area fraction. At the same time, the strength and bending workability can be improved.
The lower limit of the 0.2% proof stress is preferably 520 MPa or more, and more preferably 550 MPa or more.

  Next, a preferred example of a method for producing a copper alloy for electronic / electric equipment according to the above-described embodiment will be described with reference to the flowchart shown in FIG.

[Melting / Casting Process: S01]
First, a molten copper alloy having the above-described component composition is melted. As the copper raw material, it is desirable to use 4NCu (oxygen-free copper or the like) having a purity of 99.99 mass% or more, but scrap may be used as a raw material. In addition, an atmospheric furnace may be used for melting, but an atmosphere furnace having a vacuum furnace, an inert gas atmosphere, or a reducing atmosphere may be used in order to suppress oxidation of the additive element.
Next, the ingot is obtained by casting the adjusted copper alloy molten metal by an appropriate casting method, for example, a batch casting method such as die casting, or a continuous casting method, a semi-continuous casting method, a horizontal continuous casting method, or the like. .

[Homogenization heat treatment step: S02]
Thereafter, if necessary, homogenization heat treatment is performed to eliminate segregation of the ingot to make the ingot structure uniform, or to dissolve inclusions and precipitates. The conditions for this homogenization heat treatment are not particularly limited, but it may be usually heated at a temperature of 600 ° C. to 1000 ° C. for 1 hour to 24 hours. If the heat treatment temperature is less than 600 ° C. or the heat treatment time is less than 1 hour, a sufficient homogenization effect or solution effect may not be obtained. On the other hand, if the heat treatment temperature exceeds 1000 ° C., a part of the segregation site may be dissolved, and if the heat treatment time exceeds 24 hours, only the cost increases. The cooling conditions after the heat treatment may be determined as appropriate, but usually water quenching may be performed. After the heat treatment, chamfering is performed as necessary.

[Hot working process: S03]
Next, hot working may be performed on the ingot in order to increase the efficiency of roughing and make the structure uniform. The conditions for this hot working are not particularly limited, but it is usually preferable that the start temperature is 600 ° C. or higher and 1000 ° C. or lower, the end temperature is 550 ° C. or higher and 850 ° C. or lower, and the processing rate is 50% or higher. The ingot heating up to the hot working start temperature may be combined with the above-described homogenization heat treatment step S02. Cooling conditions after hot working may be determined as appropriate, but usually water quenching may be performed. In addition, after hot processing, it chamfers as needed. Although it does not specifically limit about the processing method of hot processing, What is necessary is just to apply hot rolling, when a final shape is a board or a strip. If the final shape is a wire or a rod, extrusion or groove rolling may be applied, and if the final shape is a bulk shape, forging or pressing may be applied. When the end temperature is less than 550 ° C., coarse [Ni, Fe] -P-based precipitates or [Ni, Fe, Co] -P-based precipitates are present during hot working. For this reason, the temperature at the end of hot rolling should be 550 ° C. or higher, preferably 600 ° C. or higher, and water-cooled.

[Coarse plastic working step: S04]
Next, rough plastic working is performed on the ingot homogenized in the homogenizing heat treatment step S02 or the hot work material subjected to the hot working step S03 such as hot rolling. The temperature condition in the rough plastic working step S04 is not particularly limited, but is preferably less than 200 ° C. The processing rate of the intermediate plastic processing is not particularly limited, but is usually about 10 to 99%. Although the processing method is not particularly limited, rolling may be applied when the final shape is a plate or strip. When the final shape is a wire or a rod, extrusion or groove rolling can be applied, and when the final shape is a bulk shape, forging or pressing can be applied.

[Solution heat treatment step: S05]
Subsequent to the rough plastic working step S04, reduction of Zn segregation in the matrix phase and solution heat treatment for dissolving inclusions and precipitates are performed. Usually, it is carried out at a temperature of 600 ° C. to 1000 ° C. for 0.1 seconds to 24 hours. When heat treatment is performed at a high temperature, the heat treatment is performed for a short time. When heat treatment is performed at a low temperature, the heat treatment is performed for a long time. After solution heat treatment, it is preferable to cool to 300 ° C. or less at a cooling rate of 1 ° C./min or more. More preferably, it is 10 ° C./min or more. For thorough solution, the rough plastic working step S04 and the solution heat treatment step S05 may be repeated.

[Intermediate plastic working process: S06]
Next, after the solution heat treatment step S05, intermediate plastic working is performed. The temperature condition in the intermediate plastic working step S06 is not particularly limited, but is preferably less than 200 ° C. The processing rate of the intermediate plastic processing is not particularly limited, but is usually about 10 to 99%. Although the processing method is not particularly limited, rolling may be applied when the final shape is a plate or strip. When the final shape is a wire or a rod, extrusion or groove rolling can be applied, and when the final shape is a bulk shape, forging or pressing can be applied.

[Intermediate heat treatment step: S07]
After the cold or warm intermediate plastic working step S06, an intermediate heat treatment that serves both as a recrystallization process and as a precipitation process is performed. This intermediate heat treatment is a process performed to recrystallize the structure and simultaneously disperse and precipitate [Ni, Fe] -P-based precipitates or [Ni, Fe, Co] -P-based precipitates. The conditions of the heating temperature and the heating time at which the precipitates are generated may be applied, and the conditions are usually maintained at a temperature of 400 ° C. to 800 ° C. for 1 second to 24 hours. However, since the crystal grain size has some influence on the stress relaxation resistance, it is desirable to measure the recrystallized grains by the intermediate heat treatment and appropriately select the heating temperature and heating time conditions. That is, when the heat treatment temperature is high, the heat treatment time is short, and when the heat treatment temperature is low, the heat treatment time is long. In addition, since the intermediate heat treatment and subsequent cooling affect the final average crystal grain size, these conditions are selected so that the average crystal grain size of the parent phase is in the range of 0.5 μm to 20 μm. It is preferable to select such that it is within a range of 1 μm or more and 15 μm or less.

As a specific method of the intermediate heat treatment, a batch-type heating furnace may be used, or continuous heating may be performed using a continuous annealing line. When using a batch-type heating furnace, it is desirable to heat at a temperature of 400 ° C. or higher and 600 ° C. or lower for 1 hour or longer and 24 hours or shorter, and when using a continuous annealing line, a heating ultimate temperature of 600 ° C. or higher and 900 ° C. or lower is used. It is preferable that the temperature be kept below and maintained at a temperature within the range for about 1 second to 5 minutes. The atmosphere for the intermediate heat treatment is preferably a non-oxidizing atmosphere (nitrogen gas atmosphere, inert gas atmosphere, reducing atmosphere).
Although the cooling conditions after the intermediate heat treatment are not particularly limited, the cooling is usually performed at a cooling rate of about 2000 ° C./second to 100 ° C./hour.
If necessary, the intermediate plastic processing step S06 and the intermediate heat treatment step S07 may be repeated a plurality of times.

[Finishing plastic working process: S08]
After the intermediate heat treatment step S07, finishing is performed to the final dimensions and the final shape. The processing method is not particularly limited, but rolling (cold rolling) may be applied when the final product form is a plate or a strip. In addition, forging, pressing, groove rolling, or the like may be applied depending on the final product form. The processing rate of the finish plastic working is an important process in which the area ratio with respect to the measurement area of the crystal grains having an aspect ratio b / a of 0.1 or less is 40% or more in the area fraction. When the processing rate is 70% or less, the area ratio with respect to the measurement area of the crystal grains having an aspect ratio b / a of 0.1 or less is not sufficiently increased. Further, when the processing rate is 98% or more, the rolling cost increases. For this reason, the processing rate is preferably in the range of more than 70% and less than 98%. More preferably, it is 75% or more and less than 98%. In order to reliably increase the area ratio of the crystal grains with an aspect ratio b / a of 0.1 or less to the measurement area, it is preferable to apply a tension of 1 MPa or more in the rolling direction.

[Finish heat treatment step: S09]
After the finish plastic working, the finish heat treatment step S09 is performed for the purpose of improving the stress relaxation resistance, improving the stress corrosion cracking characteristics by removing the residual strain, and improving the bending workability. This finish heat treatment is desirably performed at a temperature in the range of 200 ° C. to 800 ° C. for 1 second to 24 hours. If the finish heat treatment temperature is less than 200 ° C. or the finish heat treatment time is less than 0.1 seconds, there is a risk that sufficient distortion removal effects may not be obtained. There is a fear of crystallizing, and the fact that the finishing heat treatment time exceeds 24 hours only increases the cost.

Here, in the finish heat treatment step S09, when the heat treatment temperature is high, the heat treatment time is short, and when the heat treatment temperature is low, the heat treatment time is long.
In this finishing heat treatment step S09, when the Vickers hardness Hv_CR at room temperature after the finishing plastic processing step S08 and the Vickers hardness at room temperature after the finishing heat treatment step S09 are Hv_HT, Hv_CR−Hv_HT which is the difference between them is 5Hv. With the above, the 0.2% proof stress is within the range of 500 MPa to less than 650 MPa without reducing the area ratio with respect to the measurement area of the crystal grains having an aspect ratio b / a of 0.1 or less. Aims to improve ductility and bendability.
Note that the value of Hv_CR-Hv_HT is preferably 7 Hv or more. More preferably, it is 10HV or more, More preferably, it is 15Hv or more.

As described above, the copper alloy for electronic / electric equipment according to the present embodiment can be obtained. In this copper alloy for electronic / electric equipment, cracks do not occur even when a W-shaped bending test is performed using a W-shaped jig having a bending radius of 0 mm.
Moreover, when rolling is applied as a processing method, a copper alloy thin plate (strip material) for electronic and electrical equipment having a plate thickness of 0.05 mm or more and 1.0 mm or less can be obtained. Such a thin plate may be used as it is for a conductive part for electronic / electric equipment, but Sn plating with a film thickness of about 0.1 to 10 μm is applied to one or both sides of the plate surface, and Sn plating is provided. The copper alloy strip is usually used for conductive parts for electronic and electrical equipment such as connectors and other terminals. In this case, the Sn plating method is not particularly limited. In some cases, a reflow treatment may be performed after electrolytic plating.

  In the copper alloy for electronic / electric equipment according to the present embodiment configured as described above, [Ni, Fe] -P-based precipitates or [Ni, Fe, Co] -P-based precipitates are formed from the parent phase. At the same time, the area ratio of the crystal grains where the aspect ratio b / a of the parent phase is 0.1 or less is 40% or more in the area fraction, so that the stress relaxation resistance is ensured. In addition, it is sufficiently excellent and has excellent stress corrosion cracking resistance, high strength (proof stress), and other characteristics such as electrical conductivity.

  Furthermore, in the copper alloy for electronic / electric equipment according to the present embodiment, the 0.2% proof stress is adjusted to 500 MPa or more and less than 650 MPa, and has excellent mechanical properties and excellent bending workability. This is particularly suitable for conductive parts that require high strength, such as a movable conductive piece or a spring part of a terminal.

  In addition, in the copper alloy for electronic and electrical equipment according to the present embodiment, a W-shaped jig having a bending radius of 0 mm is used, and cracks do not occur even when a W bending test is performed. Therefore, it is possible to form various shapes of conductive parts for electronic and electrical equipment by bending.

Since the copper alloy thin plate for electronic / electric equipment according to the present embodiment is made of the above-described rolled material of copper alloy for electronic / electric equipment, it has excellent stress relaxation resistance, stress corrosion cracking resistance, and bending workability. , Connectors, other terminals, movable conductive pieces of electromagnetic relays, lead frames, and the like.
Moreover, when Sn plating is given to the surface, components, such as a used connector, are collect | recovered as scraps of Sn plating Cu-Zn type alloy, and favorable recyclability can be ensured.

  The conductive member for electronic / electric equipment according to the present embodiment is made of the above-described copper alloy thin plate for electronic / electrical equipment, and is a conductive material for obtaining electrical connection with the counterpart conductive member by contacting with the counterpart conductive member. It is a member, and at least a part of the plate surface is subjected to a bending process, and is configured to maintain contact with the mating conductive material by the spring property of the bent portion, so that the stress relaxation resistance is improved. It is excellent and the residual stress is less likely to be relaxed over time or in a high temperature environment, and the contact pressure with the counterpart conductive member can be maintained.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.
For example, although an example of the manufacturing method has been described, the present invention is not limited thereto, and the finally obtained copper alloy for electronic / electric equipment has a composition within the scope of the present invention, and Cu, Zn The aspect ratio and the yield strength of the parent phase containing Sn and Sn may be set within the scope of the present invention.

  Below, the result of the confirmation experiment conducted in order to confirm the effect of this invention is shown. The following examples are for explaining the effects of the present invention, and the configurations, processes, and conditions described in the examples do not limit the technical scope of the present invention.

First, a raw material consisting of Cu-40 mass% Zn master alloy and oxygen-free copper (ASTM B152 C10100) with a purity of 99.99 mass% or more was prepared, charged in a high-purity graphite crucible, and N ₂ gas atmosphere. It melt | dissolved using the electric furnace. Various additive elements were added to the molten copper alloy to melt the molten alloy having the composition shown in Table 1, and poured into a carbon mold to produce an ingot. The size of the ingot was about 40 mm thick × about 70 mm wide × about 100 mm long.
Subsequently, each ingot was subjected to water quenching as a homogenization treatment after being held for a predetermined time at a temperature shown in Table 2 in an N ₂ gas atmosphere.

  Next, hot rolling was performed. Reheating so that the hot rolling start temperature becomes the temperature shown in Table 2, the width direction of the ingot becomes the rolling direction, and the rolling end temperature is 600 ° C. or higher while appropriately performing the reheating. It was made to become. After the hot rolling, water quenching was performed, and after cutting and surface grinding, a hot rolled material having a thickness of about 20 mm, a width of about 160 mm, and a length of about 100 mm was produced.

Thereafter, rough plastic working and solution heat treatment were performed.
Specifically, after cold rolling at a rolling rate of about 20% or more, solution heat treatment was performed for 1 hour to 4 hours at a temperature shown in Table 2, and water quenching was performed.
After solution heat treatment, after cutting and surface grinding, cold working was performed at a rolling rate of 70% or more, and intermediate heat treatment was performed at a temperature shown in Table 2 for 1 minute to 4 hours. After the intermediate heat treatment, it was cut and surface grinding was performed to remove the oxide film. In addition, the crystal grain size was measured from the sample after the intermediate heat treatment, and it was confirmed that any of the inventive examples and the comparative examples had an average grain size in the range of 3 to 10 μm.

The average crystal grain size after the intermediate heat treatment was examined as follows.
A surface orthogonal to the width direction of rolling, that is, a TD (Transverse Direction) surface is used as an observation surface, mirror polishing, etching, and then taking an optical microscope so that the rolling direction is next to the photograph, Observation was performed with a 1000 × field of view (approximately 300 × 200 μm ² ). Then, according to the cutting method of JIS H 0501, the crystal grain size is drawn by 5 lines each having a predetermined length in the vertical and horizontal directions, the number of crystal grains to be completely cut is counted, and the average value of the cutting lengths is averaged. Calculated as the crystal grain size.

  Thereafter, finish rolling was performed at the rolling rates shown in Table 2. In finish rolling, Example No. of the present invention. In the present invention example and comparative example Nos. 1, 2 and 4 except 2, when the thickness becomes about 1 mm, the rolling is temporarily stopped for each rolling pass, and 10 kg weights are suspended at both ends. After rolling, when the vicinity of the rear end was reached, the rolling was stopped and the weight was removed. This operation was repeated until the thickness was about 0.25 mm. The part rolled with a weight was left, and the others were cut.

Finally, after finishing heat treatment is performed for 1 to 5 minutes at the temperature shown in Table 2, water quenching, cutting and surface polishing are performed, and then a strip for property evaluation having a thickness of 0.25 mm and a width of about 160 mm Was produced.
At this time, the hardness Hv_CR of the rolled surface before the finish heat treatment, that is, the ND surface (Normal Direction), and the hardness Hv_HT of the ND surface after the finish heat treatment were measured, and the hardness difference Hv_CR−Hv_HT was calculated. The Vickers hardness was measured at a test load of 1.96 N (= 0.2 kgf) or 0.98 N (= 0.1 kgf) in accordance with the microhardness test method defined in JIS-Z2248. The hardness difference is shown in Table 2.

  These strips for property evaluation were subjected to structure observation to evaluate the aspect ratio of the parent phase. In addition, the electrical conductivity, mechanical properties (yield strength), stress relaxation properties, stress corrosion cracking properties, and bending workability were evaluated. The test method and measurement method for each evaluation item are as follows, and the results are shown in Table 3.

〔aspect ratio〕
Using the surface perpendicular to the rolling width direction, that is, the TD surface (Transverse direction) as the observation surface, mechanical polishing is performed using water-resistant abrasive paper and diamond abrasive grains, and then final polishing is performed using a colloidal silica solution. It was. And an EBSD measuring device (Quanta FEG 450 made by FEI, EDAX / TSL (current AMETEK) OIM Data Collection), and analysis software (EDAX / TSL (current AMETEK) OIM Data Analysis ver. 7.1). ), The orientation of each crystal grain (including twins) except for the measurement point where the acceleration value of the electron beam is 20 kV, the measurement area is 200 μm ² or more at a measurement interval of 0.03 μm, and the CI value is 0.1 or less. The difference is analyzed, and when the major axis of the crystal grain size of each crystal grain is a and the minor axis is b and b / The area fraction of the aspect ratio represented by a was measured. In the measurement of the aspect ratio, Grain Size on EBSD was measured with Grain Tolerance Angle of 5 ° and Minimum Grain Size of 2 pixels.

〔conductivity〕
A test piece having a width of 10 mm and a length of 60 mm was taken from the strip for characteristic evaluation, and the electrical resistance was determined by a four-terminal method. Moreover, the dimension of the test piece was measured using the micrometer, and the volume of the test piece was calculated. And electrical conductivity was computed from the measured electrical resistance value and volume. In addition, the test piece was extract | collected so that the longitudinal direction might become parallel with the rolling direction of the strip for characteristic evaluation.

(Mechanical properties)
A No. 13B test piece defined in JIS Z 2201 was taken from the strip for characteristic evaluation, and 0.2% proof stress σ _0.2 was measured by an offset method of JIS Z 2241. In addition, the test piece was extract | collected so that the tension direction of a tension test might become a direction orthogonal to the rolling direction of the strip for characteristic evaluation.

[Stress relaxation resistance]
In the stress relaxation resistance test, stress was applied by a method according to the cantilever screw method of Japan Copper and Brass Association Technical Standard JCBA-T309: 2004, and the residual stress ratio after holding for a predetermined time at a temperature of 180 ° C. was measured. .
As a test method, a specimen (width 10 mm) is taken from each characteristic evaluation strip in a direction parallel to the rolling direction, and the initial deflection displacement is set so that the maximum surface stress of the specimen is 80% of the proof stress. The span length was adjusted to 2 mm. The maximum surface stress is determined by the following equation.
Maximum surface stress (MPa) = 1.5 Etδ ₀ / L _s ²
However,
E: Deflection coefficient (MPa)
t: sample thickness (t = 0.25 mm)
δ ₀ : Initial deflection displacement (2 mm)
L _s : Span length (mm)
It is.

The stress relaxation resistance was evaluated by measuring the residual stress rate after holding for 24 hours at a temperature of 180 ° C. to evaluate the stress relaxation characteristics. The residual stress rate was calculated using the following formula.
Residual stress rate (%) = (1−δ _t / δ ₀ ) × 100
However,
δ _t : Permanent deflection displacement after holding for 24 h at 180 ° C. (mm) −Permanent deflection displacement after holding for 24 h at room temperature (mm)
δ ₀ : Initial deflection displacement (mm)
It is.
Those having a residual stress rate of 70% or more were evaluated as “◯”, and those having a residual stress ratio of less than 70% were evaluated as “X”.

[Stress corrosion cracking resistance]
The stress corrosion cracking resistance is H. Investigation was performed according to the stress corrosion cracking test method of THOMPSON (Materials, Res. And Stds. 1 (1961), P108-111). That is, a test piece having a width of 10 mm and a length of 60 mm was taken in parallel with the rolling direction, and the central portion in the length direction was bent at a radius of curvature R: 2 mm, and both ends were constrained in a loop shape, and stress was applied. After applying and holding at room temperature for 24 hours, once the restraint was removed, the initial displacement δ _RT was measured, both ends were restrained again, and this was stored in a 10 L volume containing about 1% of about 5% ammonia water. The test piece restrained in a loop shape was placed in the gas phase, held at 25 ° C., and after 96 hours, the loop-like restraint was removed and the displacement δ _96h of the test piece was measured. Were measured to calculate the initial amount of displacement [delta] _RT and displacement [delta] residual stress rate from the following equation using the _96h (%).
Residual stress rate (%) = (1-δ _96h / δ _RT ) × 100
Measured at n = 5 from the samples of the examples and comparative examples of the respective compositions, the average residual stress ratio is 90% or more “◎”, 80% or more “○” less than 80% Was evaluated as “×”.

[Bending workability]
Bending was performed in accordance with four test methods of JCBA (Japan Copper and Brass Association Technical Standard) T307-2007. W bending was performed so that the bending axis was orthogonal to the rolling direction. A plurality of test pieces of width 10 mm x length 30 mm x thickness 0.25 mm are taken from the strip for characteristic evaluation, and a W-bending test is performed using a W-shaped jig having a bending angle of 90 degrees and a bending radius of 0 mm. It was. Each of the three samples was subjected to a cracking test, and “◯” indicates that no crack was observed in the four visual fields of each sample, and “X” indicates that the crack was observed in one or more visual fields.

In Comparative Example 1 in which the Zn content was 14.2 mass%, the stress corrosion cracking resistance was insufficient. For this reason, bending workability was not evaluated.
In Comparative Example 2 that does not contain Ni, Fe, or P, the stress relaxation resistance was insufficient. For this reason, stress corrosion cracking resistance and bending workability were not evaluated.
In Comparative Example 3 in which the proportion of crystal grains having an aspect ratio of 0.1 or less was 3%, the stress corrosion cracking resistance was insufficient. For this reason, bending workability was not evaluated.
In Comparative Example 4 in which the proof stress was 716 MPa, the stress relaxation resistance and the stress corrosion cracking resistance were good, but the bending workability was insufficient.

On the other hand, In Invention Example 1-12, the stress relaxation resistance, the stress corrosion cracking resistance, and the bending workability were excellent. Moreover, it was excellent also in electrical conductivity and yield strength.
From the above, according to the examples of the present invention, a copper alloy for electronic / electric equipment having excellent stress relaxation resistance and sufficient strength, excellent strength, stress corrosion cracking resistance, and excellent bending workability. It was confirmed that it could be provided.

Claims (9)

Zn is more than 7 mass% and less than 13 mass%, Sn is 0.1 mass% or more and 0.9 mass% or less, Ni is 0.05 mass% or more and less than 1.0 mass%, Fe is 0.001 mass% or more and less than 0.10 mass%, P 0.005 mass% or more and 0.1 mass% or less, and the balance consists of Cu and inevitable impurities,
The ratio Fe / Ni between the Fe content and the Ni content is the atomic ratio,
0.002 ≦ Fe / Ni <1.5
The filling,
And the ratio of the total content of Ni and Fe (Ni + Fe) to the content of P (Ni + Fe) / P is the atomic ratio,
3 <(Ni + Fe) / P <15
The filling,
Furthermore, the ratio Sn / (Ni + Fe) between the Sn content and the total amount of Ni and Fe (Ni + Fe) is the atomic ratio,
0.3 <Sn / (Ni + Fe) <5
While satisfying
Using a plane perpendicular to the width direction of rolling as an observation plane, a parent phase containing Cu, Zn, and Sn is measured by measuring the measurement area of 200 μm ² or more by the EBSD method at a measurement interval of 0.03 μm. When the analysis is performed except for the measurement point where the CI value analyzed by the soft OIM is 0.1 or less, the aspect ratio b / a represented by the major axis a and the minor axis b of the crystal grain size (including twins) is The area ratio of the crystal grains that is 0.1 or less is 40% or more of the total area measured by Area fraction,
A copper alloy for electronic and electrical equipment, wherein the 0.2% proof stress is 500 MPa or more and less than 650 MPa. Zn is more than 7 mass% and less than 13 mass%, Sn is 0.1 mass% or more and 0.9 mass% or less, Ni is 0.05 mass% or more and less than 1.0 mass%, Fe is 0.001 mass% or more and less than 0.10 mass%, Co 0.001 mass% or more and less than 0.1 mass%, P is contained 0.005 mass% or more and 0.1 mass% or less, and the balance consists of Cu and inevitable impurities,
The ratio of the total content of Fe and Co to the content of Ni (Fe + Co) / Ni is the atomic ratio,
0.002 ≦ (Fe + Co) / Ni <1.5
The filling,
And the ratio (Ni + Fe + Co) / P of the total content of Ni, Fe and Co (Ni + Fe + Co) to the content of P is an atomic ratio,
3 <(Ni + Fe + Co) / P <15
The filling,
Furthermore, the ratio Sn / (Ni + Fe + Co) between the Sn content and the total content of Ni, Fe and Co (Ni + Fe + Co) is the atomic ratio,
0.3 <Sn / (Ni + Fe + Co) <5
The filling,
Using a plane perpendicular to the width direction of rolling as an observation plane, a parent phase containing Cu, Zn, and Sn is measured by measuring the measurement area of 200 μm ² or more by the EBSD method at a measurement interval of 0.03 μm. When the analysis is performed except for the measurement point where the CI value analyzed by the soft OIM is 0.1 or less, the aspect ratio b / a represented by the major axis a and the minor axis b of the crystal grain size (including twins) is The area ratio of the crystal grains that is 0.1 or less is 40% or more of the total area measured by Area fraction,
A copper alloy for electronic and electrical equipment, wherein the 0.2% proof stress is 500 MPa or more and less than 650 MPa. In the copper alloy for electronic and electrical equipment according to claim 1 or claim 2,
A copper alloy for electronic and electrical equipment, wherein a crack is not generated even when a W-bending test is performed using a W-shaped jig having a bending radius of 0 mm.   It consists of a rolled material of the copper alloy for electronic and electrical equipment as described in any one of Claims 1-3, and thickness exists in the range of 0.05 mm or more and 1.0 mm or less, Copper alloy sheet for electrical equipment. In the copper alloy thin plate for electronic and electrical equipment according to claim 4,
A copper alloy thin plate for electronic and electrical equipment, characterized by Sn plating on the surface.   A conductive component for electronic / electric equipment comprising the copper alloy for electronic / electric equipment according to claim 1.   A terminal comprising the copper alloy for electronic and electrical equipment according to claim 1 or 2.   An electrically conductive component for electronic / electric equipment comprising the copper alloy thin plate for electronic / electric equipment according to claim 4 or 5.   A terminal comprising the copper alloy thin plate for electronic and electrical equipment according to claim 4 or 5.

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