JP6218325B2 - Copper alloy for electronic and electrical equipment, copper alloy sheet for electronic and electrical equipment, conductive parts and terminals for electronic and electrical equipment - Google Patents

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 so as to obtain electrical connection with the mating conductive member by bringing it into contact with the mating conductive member in the vicinity of the bent portion and to maintain the contact state with the mating conductive member due to 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, in the case of a connector or the like used to maintain a contact state with the mating conductive member in the vicinity of the bent portion by applying the bending process and the spring property of the bent portion, the bending workability, It is required that the stress relaxation resistance is excellent.

Thus, for example, Patent Documents 1 to 4 propose methods for improving the stress relaxation resistance of Cu—Zn—Sn alloys.
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. An improvement in strength, elasticity, and heat resistance is considered to mean an improvement in 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.

JP-A-5-33087 JP 2006-283060 A Japanese Patent No. 3953357 Japanese Patent No. 3717321

Recently, electronic and electrical devices have been further reduced in size and weight, and in copper alloys for electronic and electrical devices used for conductive parts for electronic and electrical devices, further strength, bending workability, There is a need for improved stress relaxation properties.
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.

  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. 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. Therefore, further reliable and sufficient improvement of the stress relaxation resistance is strongly desired.

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

As a result of intensive experiments and researches, the inventors of the present invention have added a proper amount of Ni to a Cu—Zn—Sn alloy, and added a proper amount of P, and the ratio Ni between the Ni content and the P content is Ni. Ni / P-based precipitates containing Ni and P can be obtained by adjusting the Sn / Ni ratio of Sn / Ni and the ratio Sn / Ni between the Sn content and the Ni content within appropriate ranges. At the same time, Ni-P-based precipitates having an average particle size of 10 or more per 1 μm ³ and a particle size of more than 100 nm and less than 500 nm are deposited at the same time. Precipitates exist in an average of 0.005 or more and 10 or less per 1 μm ³ , and the average grain size of α-phase crystal grains containing Cu, Zn and Sn is within a range of 0.1 μm or more and 50 μm or less. Ensures stress relaxation resistance At the same time be sufficiently improved, strength, bending workability excellent copper alloy has been found to be obtained.

Further, appropriate amounts of Fe and Co are added simultaneously with the above Ni and P, the ratio of the total content of Ni, Fe and Co to the content of P (Ni + Fe + Co) / P, the Sn content and the Ni, Fe content The ratio Sn / (Ni + Fe + Co) to the total content of Co and Co and the ratio (Fe + Co) / Ni of the total content of Fe and Co to the content of Ni (Fe + Co) / Ni are adjusted within appropriate ranges in terms of atomic ratios. Thus, a [Ni, (Fe, Co)]-P-based precipitate containing at least one element selected from the group consisting of Fe, Co, and Ni and P is appropriately deposited, and at the same time, the particle diameter is 1 nm. More than 10 [Ni, (Fe, Co)]-P-based precipitates in the range of 100 nm or more on average, and [Ni, (Fe, Co) in the range of particle diameters exceeding 100 nm and less than 500 nm per 1 μm ^3. )]-P-based precipitates With there 0.005 or more 10 or less on average per 1 [mu] m ^3, Cu, by an average grain size of crystal grains of α phase containing Zn and Sn is in the range of 0.1μm or more 50μm or less, resistance It has been found that the stress relaxation characteristics and strength can be further improved.
The present invention has been made based on these findings.

The copper alloy for electronic / electrical equipment according to the present invention is more than 2.0 mass% Zn and 36.5 mass% or less, Sn is 0.10 mass% or more and 0.90 mass% or less, Ni is 0.15 mass% or more and 1.00 mass%. %, P is contained in an amount of 0.005 mass% to 0.100 mass%, the balance is made of Cu and inevitable impurities, and the ratio of Ni content to P content Ni / P is 3 in atomic ratio. 0.0 <Ni / P <100.0, and the ratio Sn / Ni between the Sn content and the Ni content satisfies 0.10 <Sn / Ni <2.90 in atomic ratio, Furthermore, it has Ni-P-based precipitates containing Ni and P, and the average particle size of the Ni-P-based precipitates in the range of 1 nm to 100 nm is 10 or more per 1 μm ^3. The diameter exceeds 100nm With Ni-P-based precipitates within the range of less than 00nm is present in average per 1 [mu] m ³ 0.005 or more 10 or less, Cu, average particle diameter of the crystal grains of the α phase containing Zn and Sn 0. It is characterized by being in the range of 1 μm or more and 50 μm or less.

According to the copper alloy for electronic and electrical equipment having the above-described configuration, Ni is added together with P, and the addition ratio of Sn, Ni, and P is regulated, and Ni precipitated from the parent phase (mainly α phase) has a Ni-P-based precipitates containing a P, the particle diameter of the Ni-P-based precipitates in a range of 1nm or 100nm or less on average per 1 [mu] m ³ 10 or more, than the 100nm particle size In addition, 0.005 or more and 10 or less Ni-P-based precipitates within a range of less than 500 nm are present on an average per 1 μm ³ , and the average grain size of α-phase crystal grains containing Cu, Zn and Sn is 0 Since the thickness is in the range of 1 μm or more and 50 μm or less, the stress relaxation resistance is surely and sufficiently excellent, and the strength (proof strength) is high.
Here, the Ni-P-based precipitates are Ni-P binary precipitates, and other elements such as Cu, Zn, Sn as main components, O, S, C as impurities, It may contain multi-component precipitates containing Co, Cr, Mo, Mn, Mg, Zr, Ti and the like. Further, the Ni-P-based precipitate exists in the form of a phosphide or an alloy in which phosphorus is dissolved.

Moreover, the copper alloy for electronic / electrical equipment according to the present invention has Zn exceeding 2.0 mass% to 36.5 mass% or less, Sn from 0.10 mass% to 0.90 mass%, and Ni from 0.15 mass% to 1 0.001 mass% or less and P containing 0.005 mass% or more and 0.100 mass% or less, and either Fe of 0.001 mass% or more and less than 0.100 mass% and Co of 0.001 mass% or more and less than 0.100 mass% Or both of which are composed of Cu and inevitable impurities, and the ratio of the total content of Ni, Fe and Co (Ni + Fe + Co) to the content of P (Ni + Fe + Co) / P is 3.0 by atomic ratio. <(Ni + Fe + Co) / P <100.0, and Sn content and total content of Ni, Fe and Co The ratio Sn / (Ni + Fe + Co) to (Ni + Fe + Co) satisfies an atomic ratio of 0.10 <Sn / (Ni + Fe + Co) <2.90, and the ratio of the total content of Fe and Co to the content of Ni ( (Fe + Co) / Ni satisfies an atomic ratio of 0.002 ≦ (Fe + Co) / Ni <1.500, and further contains at least one element selected from the group consisting of Fe, Co, and Ni and P. It has [Ni, (Fe, Co)]-P-based precipitates, and the [Ni, (Fe, Co)]-P-based precipitates having a particle diameter in the range of 1 nm to 100 nm per 1 μm ³ [Ni, (Fe, Co)]-P-based precipitates having an average of 10 or more and a particle diameter of more than 100 nm and less than 500 nm exist on an average of 0.005 or more and 10 or less per 1 μm ^3. , C , And wherein the average particle diameter of the crystal grains of the α phase containing Zn and Sn is in the range of 0.1 to 50μm or less.

According to the copper alloy for electronic and electrical devices having the above-described configuration, Ni is added together with P, and furthermore, an appropriate amount of Fe and Co is added to regulate the addition ratio among Sn, Ni, Fe, Co and P. And [Ni, (Fe, Co)]-P-based precipitates containing at least one element selected from the group consisting of Fe, Co, and Ni, and P precipitated from the parent phase (mainly α-phase) The average particle size of 10 or more [Ni, (Fe, Co)]-P-based precipitates in the range of 1 nm to 100 nm in particle size is 1 μm ³ or more, and the particle size is in the range of more than 100 nm and less than 500 nm. [Ni, (Fe, Co)]-P-based precipitates in an average of 0.005 or more and 10 or less per 1 μm ³ and the average grain size of α-phase crystal grains containing Cu, Zn and Sn Within the range of 0.1 μm to 50 μm Since it is, and stress relaxation resistance superior reliably and sufficiently, yet strength (yield strength) is high.
Here, [Ni, (Fe, Co)]-P-based precipitates are Ni-P, Fe-P or Co-P binary precipitates, Ni-Fe-P, Ni-Co-P. Alternatively, it is a ternary precipitate of Fe—Co—P or a quaternary precipitate of Ni—Fe—Co—P, and further, other elements such as Cu, Zn, Sn, and O as impurities. , S, C, Cr, Mo, Mn, Mg, Zr, Ti, and the like may be included. Moreover, this [Ni, (Fe, Co)]-P-based precipitate exists in the form of a phosphide or an alloy in which phosphorus is dissolved.

The copper alloy thin plate for electronic / electrical equipment of the present invention is made of the above-mentioned rolled material of copper alloy for electronic / electrical equipment and has a thickness in the range of 0.05 mm to 1.0 mm.
The rolled sheet thin plate (strip material) having such a thickness 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 Sn of 0.10 mass% or more and 0.90 mass% or less. It can be recovered as a scrap of Cu—Zn alloy to ensure good recyclability.

The conductive component for electronic / electrical equipment of the present invention is characterized by comprising the above-described copper alloy for electronic / electrical 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 conductive parts for electronic / electrical equipment in the present invention include terminals, connectors, relays, lead frames and the like.

The terminal of the present invention is characterized by comprising the above-described copper alloy for electronic and electrical equipment.
Furthermore, the terminal of the present invention is characterized by comprising the above-described copper alloy thin plate for electronic and electrical equipment.
The terminals in the present invention include connectors and the like.

  According to the conductive parts and terminals for electronic / electrical equipment having these configurations, since the stress relaxation resistance is particularly excellent, the residual stress is hardly relaxed over time or in a high temperature environment, and the reliability is excellent.

  According to the present invention, a copper alloy for electronic / electric equipment that has excellent and sufficient stress relaxation resistance and has excellent strength and bending workability, a copper alloy thin plate for electronic / electric equipment using the same, an electronic -It is possible to provide conductive parts and terminals for electrical equipment.

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. 2 is a TEM (transmission electron microscope) observation photograph (magnification of 150,000 times) showing an observation example of precipitates in an example, and an image obtained by binarizing the observation photograph. 2 is a TEM (transmission electron microscope) observation photograph (magnification 15,000 times) showing an example of observation of precipitates in an example, and an image obtained by binarizing the observation photograph.

Below, the copper alloy for electronic and electric apparatuses which is one Embodiment of this invention is demonstrated.
The copper alloy for electronic / electrical equipment according to the present embodiment is more than 2.0 mass% Zn and 36.5 mass% or less, Sn is 0.10 mass% or more and 0.90 mass% or less, Ni is 0.15 mass% or more and 1. Less than 00 mass%, P is contained in 0.005 mass% or more and 0.100 mass% or less, and the balance is composed of Cu and inevitable impurities.

And as content ratio between each alloy element, ratio Ni / P of content of Ni and content of P is atomic ratio, following (1) Formula 3.0 <Ni / P <100 0.0 (1) is satisfied, and the ratio Sn / Ni between the Sn content and the Ni content is an atomic ratio expressed by the following formula (2): 0.10 <Sn / Ni <2.90 ... is defined to satisfy (2).

  Furthermore, the copper alloy for electronic / electrical equipment which is this embodiment is further 0.001 mass% or more and less than 0.100 mass% Fe in addition to said Zn, Sn, Ni, and P, and 0.001 mass% or more 0.00. You may contain any one or both of Co below 100 mass%.

In this case, as the content ratio between the alloy elements, the ratio (Ni + Fe + Co) / P of the total content of Ni, Fe and Co (Ni + Fe + Co) to the content of P (Ni + Fe + Co) / P is the following (1 ′) The expression 3.0 <(Ni + Fe + Co) / P <100.0 (1 ′) is satisfied, and the ratio Sn / (Sn) and the total content of Ni, Fe and Co (Ni + Fe + Co) is Sn / ( Ni + Fe + Co) satisfies the following formula (2 ′) in the atomic ratio: 0.10 <Sn / (Ni + Fe + Co) <2.90 (2 ′), and the total content of Fe and Co and the content of Ni The ratio to the amount (Fe + Co) / Ni is determined so as to satisfy the following formula (3 ′): 0.002 ≦ (Fe + Co) / Ni <1.500 (3 ′) as an atomic ratio. .

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

(Zn: more than 2.0 mass% and 36.5 mass% or less)
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. If Zn is 2.0 mass% or less, the effect of reducing the material cost cannot be sufficiently obtained. On the other hand, if Zn exceeds 36.5 mass%, corrosion resistance will fall and cold rolling property will also fall.
Therefore, the Zn content is within the range of more than 2.0 mass% and not more than 36.5 mass%. The Zn content is preferably in the range of 5.0 mass% to 33.0 mass%, and more preferably in the range of 7.0 mass% to 27.0 mass%.

(Sn: 0.10 mass% or more and 0.90 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, it contributes to the improvement of stress relaxation resistance. If Sn is less than 0.10 mass%, these effects cannot be sufficiently obtained. On the other hand, if Sn exceeds 0.90 mass%, hot workability and cold rollability are deteriorated, and hot rolling and cold rolling are performed. May cause cracking, and the electrical conductivity is also lowered.
Therefore, the Sn content is set in the range of 0.10 mass% to 0.90 mass%. The Sn content is particularly preferably in the range of 0.20 mass% to 0.80 mass% even within the above range.

(Ni: 0.15 mass% or more and less than 1.00 mass%)
Ni can be added together with P to precipitate Ni—P-based precipitates from the matrix (mainly α-phase), and by adding together with one or both of Fe and Co and P, [Ni , (Fe, Co)]-P-based precipitates can be precipitated from the matrix (mainly α-phase). The average grain size can be reduced by the effect of pinning the grain boundaries during recrystallization by these Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates, and the strength Further, 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, by coexisting Ni with Sn, (Fe, Co), and P, it can be improved by solid solution strengthening. Here, if the addition amount of Ni is less than 0.15 mass%, the stress relaxation resistance cannot be sufficiently improved. On the other hand, if the amount of Ni added is 1.00 mass% or more, the amount of solid solution Ni increases and the electrical conductivity decreases, and the amount of expensive Ni raw material used increases, leading to an increase in cost.
Therefore, the Ni content is in the range of 0.15 mass% or more and less than 1.00 mass%. Note that the Ni content is preferably within a range of 0.20 mass% or more and less than 0.80 mass%, and more preferably within a range of more than 0.50 mass% and less than 0.80 mass%. . More preferably, it exists in the range of 0.55 mass% or more and less than 0.80 mass%.

(P: 0.005 mass% or more and 0.100 mass% or less)
P has a high bonding property with Ni, and if an appropriate amount of P is contained together with Ni, a Ni-P-based precipitate can be precipitated, and it is added together with one or both of Fe and Co and P. Thus, [Ni, (Fe, Co)]-P-based precipitates can be precipitated from the matrix phase (mainly α-phase). The stress relaxation resistance can be improved by the presence of these Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates. Here, if the amount of P is less than 0.005 mass%, it becomes difficult to sufficiently deposit Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates. Cannot be improved. On the other hand, if the amount of P exceeds 0.10 mass%, the amount of P solid solution increases, the electrical conductivity is lowered, and the rollability is lowered to cause cold rolling cracks.
Therefore, the content of P is set in the range of 0.005 mass% to 0.100 mass%. The content of P is particularly preferably in the range of 0.010 mass% to 0.080 mass% even within the above range.
In addition, since P is an element which is inevitably mixed from the melting raw material of the copper alloy, it is desirable to appropriately select the melting raw material in order to regulate the P content as described above. .

(Fe: 0.001 mass% or more and less than 0.100 mass%)
Fe is not necessarily an essential additive element, but if a small amount of Fe is added together with Ni and P, [Ni, Fe] -P-based precipitates can be precipitated from the matrix phase (mainly α-phase). By adding a small amount of Co, [Ni, (Fe, Co)]-P-based precipitates can be precipitated from the parent phase (mainly α-phase). The average grain size can be reduced by the effect of pinning the grain boundaries during recrystallization with 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. Here, if the addition amount of Fe is less than 0.001 mass%, the effect of further improving the stress relaxation resistance due to the addition of Fe cannot be obtained. On the other hand, if the amount of Fe added is 0.100 mass% or more, the amount of solid solution Fe increases, the electrical conductivity decreases, and the cold rollability also decreases.
Therefore, in the present embodiment, when Fe is added, the content of Fe is set in the range of 0.001 mass% or more and less than 0.100 mass%. In addition, it is preferable to make especially content of Fe into the range of 0.002 mass% or more and 0.080 mass% or less also in said range. Even when Fe is not actively added, Fe of less than 0.001 mass% may be contained as an impurity.

(Co: 0.001 mass% or more and less than 0.100 mass%)
Co is not necessarily an essential additive element, but if a small amount of Co is added together with Ni and P, a [Ni, Co] -P-based precipitate can be precipitated from the matrix (mainly α-phase). By adding a small amount of Fe, [Ni, (Fe, Co)]-P-based precipitates can be precipitated from the parent phase (mainly α-phase). These [Ni, Co] -P based precipitates or [Ni, (Fe, Co)]-P based precipitates can further improve the stress relaxation resistance. Here, if the Co addition amount is less than 0.001 mass%, a further improvement effect of the stress relaxation resistance due to Co addition cannot be obtained. On the other hand, if the Co addition amount is 0.100 mass% or more, solid solution Co As a result, the conductivity decreases, and the cost increases due to an increase in the amount of expensive Co raw materials used.
Therefore, in the present embodiment, when Co is added, the Co content is set in a range of 0.001 mass% or more and less than 0.100 mass%. Even within the above range, the Co content is preferably in the range of 0.002 mass% to 0.080 mass%. Even when Co is not actively added, Co of less than 0.001 mass% may be contained as an impurity.

  The balance of the above elements may be basically Cu and inevitable impurities. Here, as inevitable impurities, (Fe), (Co), Mg, Al, Mn, Si, 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 0.3 mass% or less in total.

  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), (2), or (1 ′) to (3 ′). Therefore, the reasons for limiting the expressions (1), (2), and (1 ′) to (3 ′) will be described below.

(1) Formula: 3.0 <Ni / P <100.0
When the Ni / P ratio is 3.0 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, resulting in coldness. Rolling cracks are likely to occur, and bending workability is also reduced. On the other hand, if the Ni / P ratio is 100.0 or more, the conductivity decreases due to an increase in the proportion of Ni dissolved, and the amount of expensive Ni raw material used is relatively increased, leading to an increase in cost. Therefore, the Ni / P ratio is regulated within the above range. The upper limit of the Ni / P ratio is 50.0 or less, preferably 40.0 or less, more preferably 20.0 or less, even less than 15.0, optimally 12.0, even within the above range. The following is desirable.

(2) Formula: 0.10 <Sn / Ni <2.90
When the Sn / Ni ratio is 0.10 or less, a sufficient effect of improving the stress relaxation resistance is not exhibited. On the other hand, when the Sn / Ni ratio is 2.90 or more, the amount of Ni becomes relatively small, and Ni− The amount of the P-based precipitate is reduced, and the stress relaxation resistance is deteriorated. Therefore, the Sn / Ni ratio is regulated within the above range. The lower limit of the Sn / Ni ratio is desirably 0.20 or more, preferably 0.25 or more, and optimally more than 0.30, even within the above range. Also, the upper limit of the Sn / Ni ratio is desirably 2.50 or less, preferably 2.00 or less, more preferably 1.50 or less, even within the above range.

(1 ') Formula: 3.0 <(Ni + Fe + Co) / P <100.0
When one or both of Fe and Co are added, it may be considered that a part of Ni is replaced by Fe and Co, and the formula (1 ′) basically conforms to the formula (1). Here, when the (Ni + Fe + Co) / P ratio is 3.0 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 is reduced. The cold rolling cracking is likely to occur and the bending workability is also lowered. On the other hand, if the (Ni + Fe + Co) / P ratio is 100.0 or more, the conductivity decreases due to an increase in the proportion of Ni, Fe, and Co dissolved, and the amount of expensive Co and Ni raw materials used is relatively large. This increases costs. Therefore, the (Ni + Fe + Co) / P ratio is regulated within the above range. The upper limit of the (Ni + Fe + Co) / P ratio is 50.0 or less, preferably 40.0 or less, more preferably 20.0 or less, even less than 15.0, optimally 12 even within the above range. 0.0 or less is desirable.

(2 ′) Formula: 0.10 <Sn / (Ni + Fe + Co) <2.90
The formula (2 ′) in the case where one or both of Fe and Co are added also conforms to the formula (2). When the Sn / (Ni + Fe + Co) ratio is 0.10 or less, a sufficient effect of improving the stress relaxation property is not exhibited. On the other hand, when the Sn / (Ni + Fe + Co) ratio is 2.90 or more, the (Ni + Fe + Co) amount is relatively large. Decreases, the amount of [Ni, (Fe, Co)]-P-based precipitates decreases, and the stress relaxation resistance decreases. Therefore, the Sn / (Ni + Fe + Co) ratio is regulated within the above range. The lower limit of the Sn / (Ni + Fe + Co) ratio is desirably 0.20 or more, preferably 0.25 or more, and optimally more than 0.30, even within the above range. In addition, the upper limit of the Sn / (Ni + Fe + Co) ratio is desirably 2.50 or less, preferably 2.00 or less, and more preferably 1.50 or less even within the above range.

(3 ′) Formula: 0.002 ≦ (Fe + Co) / Ni <1.500
When one or both of Fe and Co are added, the ratio of the total content of Ni and Fe and Co to the content of Ni is also important. When the (Fe + Co) / Ni ratio is 1.500 or more, the stress relaxation resistance is lowered, and the cost is increased due to an increase in the amount of expensive Co raw material used. When the (Fe + Co) / Ni ratio is less than 0.002, the strength decreases and the amount of expensive Ni raw material used is relatively increased, leading to an increase in cost. Therefore, the (Fe + Co) / Ni ratio is regulated within the above range. Note that the (Fe + Co) / Ni ratio is preferably in the range of 0.002 to 1.200, even within the above range. More preferably, it is in the range of 0.002 to 0.700.

  As described above, not only the individual contents but also the proportions of the respective elements adjusted to satisfy the equations (1), (2) or (1 ′) to (3 ′) -In copper alloys for electrical equipment, Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates are dispersed and precipitated from the parent phase (mainly α-phase). It is considered that the stress relaxation resistance is improved by the dispersion precipitation of the material.

Moreover, in the copper alloy for electronic and electrical equipment of the present invention, not only the component composition is adjusted as described above, but also a Ni—P based precipitate or a [Ni, (Fe, Co)] — P based precipitate. The number of is defined. Specifically, the average particle size is 10 or more per 1 μm ³ of Ni—P based precipitates or [Ni, (Fe, Co)] — P based precipitates having a particle size in the range of 1 nm to 100 nm. Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates in the range of more than 100 nm and less than 500 nm are present on average from 0.005 to 10 per 1 μm ^3. ing. The reason why the number of precipitates is defined as described above will be described below.

(Number of precipitates)
Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates precipitated from the parent phase (mainly α-phase) have a high number density per unit volume and are fine with respect to dislocations. It exhibits a pinning effect and improves strength and stress relaxation resistance.
Here, if the particle diameter of the Ni—P-based precipitate or [Ni, (Fe, Co)]-P-based precipitate is larger than 100 nm, the number density per unit volume is lowered, and the pin is sufficient for dislocation. If the particle size is less than 1 nm, the pinning effect cannot be exhibited and the strength and stress relaxation resistance cannot be improved.

The number per unit volume of Ni—P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates having a particle diameter of more than 100 nm and less than 500 nm is 1 nm to 100 nm. It affects the density distribution of Ni—P based precipitates or [Ni, (Fe, Co)] — P based precipitates within the following range. That is, if the average particle size is less than 0.005 per 1 μm ³ of Ni—P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates having a particle diameter of more than 100 nm and less than 500 nm, In the base material, a high-density region and a low-density region of Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates having a particle diameter in the range of 1 nm to 100 nm are generated, resulting in a sample. Depending on the sampling position, the stress relaxation resistance is not sufficiently improved in the portion where the precipitate density is low. Further, when Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates having a particle diameter of more than 100 nm and less than 500 nm are present in an average of more than 10 per 1 μm ³ , Since the density of precipitates having a diameter of 1 nm or more and 100 nm or less is relatively low, the stress relaxation resistance is reduced in that region.

Therefore, in the present embodiment, 10 or more Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates having a particle diameter in the range of 1 nm or more and 100 nm or less are averaged per 1 μm ^3. Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates having a diameter of more than 100 nm and less than 500 nm are deposited in an average of 0.005 or more and 10 or less per 1 μm ^3. The number of objects is specified. In this way, by defining the number of Ni—P based precipitates or [Ni, (Fe, Co)] — P based precipitates, the stress relaxation resistance is surely and sufficiently excellent, and the strength (proof strength) is also high. This makes it possible to obtain a copper alloy for electronic and electrical equipment that is high and has uniform properties.
In addition, it is preferable that 30 or more Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates having a particle diameter in the range of 1 nm to 100 nm are present on average per 1 μm ³ . Further, it is preferably 50 or more per 1 μm ^{3 on} average, and more preferably 100 or more per 1 μm ^{3 on} average. In addition, Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates having a particle diameter in the range of more than 100 nm and less than 500 nm average 0.005 or more per 5 μm ^3. It is preferably present below, and more preferably 0.010 or more and 3 or less per 1 μm ^{3 on} average.

  Furthermore, in the copper alloy for electronic and electrical equipment of the present invention, not only the component composition is adjusted as described above, but also the parent phase of the alloy, that is, the α phase in which Zn and Sn are mainly dissolved in Cu. It is also important to regulate the average grain size of the crystal grains within the range of 0.1 to 50 μm. The reason why the average grain size of the α-phase crystal grains in which Zn and Sn are mainly dissolved is mainly composed of Cu will be described below.

(Average grain size of α phase crystal grains)
It is known that the crystal grain size of the material also has some influence on the stress relaxation resistance. Generally, the stress relaxation resistance decreases as the crystal grain size decreases. On the other hand, strength and bending workability improve as the crystal grain size decreases. In the case of the alloy of the present invention, good stress relaxation resistance can be ensured by appropriate adjustment of the component composition and the ratio of each alloy element, so that the crystal grain size can be reduced to improve the strength and bending workability. it can. Here, at the stage after the finish heat treatment for recrystallization and precipitation during the manufacturing process, if the average grain size of the α phase crystal grains is 0.1 μm or more and 50 μm or less, while ensuring the stress relaxation resistance, Strength and bending workability can be improved. If the average particle diameter of the α-phase crystal grains exceeds 50 μm, sufficient strength and bending workability cannot be obtained. On the other hand, if the average particle diameter of the α-phase crystal grains is less than 0.1 μm, the component composition and Even if the ratio of each alloy element is adjusted appropriately, it is difficult to ensure the stress relaxation resistance. The average grain size of the α phase crystal grains is preferably in the range of 0.5 μm or more and 20 μm or less, and more preferably 0.5 μm or more, in order to improve the balance between the stress relaxation resistance and the strength and bending workability. More preferably within the range of 10 μm or less.

  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 copper alloy melt whose components are adjusted is cast by an appropriate casting method, for example, a batch casting method such as die casting, a continuous casting method, a semi-continuous casting method, or the like to obtain an ingot.

[Heating step: S02]
Thereafter, if necessary, a homogenization heat treatment is performed in order to eliminate segregation of the ingot and make the ingot structure uniform. Alternatively, a solution heat treatment is performed to dissolve the crystallized product and the precipitate. The conditions for this heat treatment are not particularly limited, but usually it may be heated at 600 ° C. to 1000 ° C. for 5 minutes to 24 hours. When the heat treatment temperature is less than 600 ° C. or the heat treatment time is less than 5 minutes, there is a possibility that a sufficient homogenization effect or solution effect cannot be obtained. On the other hand, if the heat treatment temperature exceeds 1000 ° C., a part of the segregated part 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, in order to increase the efficiency of rough machining and make the structure uniform, hot working may be performed on the ingot after the heating step S02 described above. The conditions for this hot working are not particularly limited, but it is usually preferable that the starting temperature is 600 ° C. or higher and 1000 ° C. or lower, the end temperature is 300 ° C. or higher and 850 ° C. or lower, and the processing rate is 10% or higher and 99% or lower. The ingot heating up to the hot working start temperature may also serve as the heating step S02 described above. That is, the hot working may be started at the above-described hot working start temperature without cooling to near room temperature after heating in the heating 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. The hot working method is not particularly limited, but when the final shape is a plate or strip, hot rolling may be applied and rolled to a thickness of about 0.5 mm to 50 mm. Further, extrusion or groove rolling may be applied when the final shape is a wire or bar, and forging or pressing may be applied when the final shape is a bulk shape.

[Roughing process: S04]
Next, roughing is performed on the ingot subjected to the homogenization treatment in the heating step S02 or the hot-worked material subjected to the hot working step S03 such as hot rolling. The temperature condition in this roughing is not particularly limited, but is preferably in the range of −200 ° C. to + 200 ° C., which is cold or warm working. The processing rate of the roughing is not particularly limited, but is usually about 50% to 99%. Although the processing method is not particularly limited, rolling may be applied when the final shape is a plate or strip. Further, when the final shape is a wire or a rod, extrusion or groove rolling, and when the final shape is a bulk shape, forging or pressing can be applied. It should be noted that S02 to S04 may be repeated for thorough solution.

[Intermediate heat treatment step: S05]
After the rough or warm roughing step S04, an intermediate heat treatment that serves as a solution heat treatment and a recrystallization treatment is performed. Here, in the intermediate heat treatment, a batch-type heating furnace may be used, or a continuous annealing line may be used. And when implementing intermediate heat processing using a batch type heating furnace, it is preferable to heat for 5 minutes or more and 24 hours or less at the temperature of 200 to 800 degreeC. In addition, when the intermediate heat treatment is performed using the continuous annealing line, the heating ultimate temperature is 350 ° C. or higher and 800 ° C. or lower, and the temperature within this range is not maintained or is maintained for 1 second or more and 5 minutes or less. It is more preferable that the temperature reached by heating is 400 ° C. or higher and 800 ° C. or lower, and it is more preferable that the temperature within this range is not held or is maintained for about 1 second to 5 minutes. Furthermore, it is preferable to set it as 650 degreeC or more and 800 degrees C or less. As described above, the heat treatment conditions in the intermediate heat treatment step S05 vary depending on the specific means for performing the heat treatment.
The atmosphere for the intermediate heat treatment is preferably a non-oxidizing atmosphere (nitrogen gas atmosphere, inert gas atmosphere, or 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 100 ° C./hour to 2000 ° C./second. When performing the intermediate heat treatment using a continuous annealing line, it is preferable to cool at a cooling rate of about 100 ° C./min to 2000 ° C./sec until the temperature reaches 150 ° C. or lower.

[Intermediate processing step: S06]
Next, intermediate processing is performed on the intermediate heat treatment material that has undergone the intermediate heat treatment step S05. In the intermediate processing step S06, the processing rate is preferably 45% or more. By increasing the processing rate to 45% or more, the dislocation density is increased by processing, and by increasing the number of precipitation nucleation sites, fine precipitates can be generated in the parent phase at high density. Here, the processing method is not particularly limited, but rolling is employed when the final form is a plate or a strip. In addition, forging, pressing, and groove rolling may be employed. Although processing temperature is not specifically limited, It is preferable to set it as -200-200 degreeC used as cold or warm.

[Finish heat treatment step: S07]
After the intermediate processing step S06, a finish heat treatment is performed which serves as both a recrystallization process and a precipitation process. By performing this finishing heat treatment, fine Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates are precipitated at a high density.
As a specific method for the finish heat treatment, a batch-type heating furnace may be used. Or you may heat continuously using a continuous annealing line. When using a batch type heating furnace, it is preferable to heat at a temperature of 300 ° C. to 800 ° C. for 5 minutes to 24 hours, and at a temperature of 350 ° C. to 700 ° C. for 5 minutes to 24 hours. More preferably.
When a continuous annealing line is used, it is preferable that the temperature reached by heating is 350 ° C. or higher and 800 ° C. or lower, and that the temperature within that range is not held or is maintained for about 1 second to 5 minutes. It is more preferable that the temperature is 400 ° C. or higher and 800 ° C. or lower, and that the temperature is within the range and is not held or is held for about 1 second to 5 minutes.
The atmosphere for the finish heat treatment is preferably a non-oxidizing atmosphere (nitrogen gas atmosphere, inert gas atmosphere, reducing atmosphere).
In addition, in order to increase the number density of precipitates, S06 to S07 may be repeated.

[Finishing process: S08]
Next, the finishing process may be performed on the material subjected to the finishing heat treatment step S07 to the final dimension and the final shape. The plastic working method in finishing is not particularly limited, but when the final product form is a plate or a strip, rolling (cold rolling) may be applied. In addition, forging, pressing, groove rolling, or the like may be applied depending on the final product form. The processing rate may be appropriately selected according to the final plate thickness and final shape, but is preferably in the range of 1% to 95%, particularly 5% to 90%. Further, when the Zn content is less than 20 mass%, it is more preferable that the content is 35% or more and 85% or less, and when the Zn content is 20 mass% or more, 20% or more and 80% or less. If the processing rate is less than 1%, the effect of improving the yield strength cannot be obtained sufficiently. On the other hand, if the processing rate exceeds 95%, the recrystallized structure is lost, and the bending workability is deteriorated by forming the processed structure. After finishing, this may be used as a product as it is, but it is usually preferable to perform low-temperature annealing.

[Low temperature annealing process: S09]
After finishing, if necessary, low-temperature annealing is performed for improving stress relaxation resistance and low-temperature annealing hardening, or for removing residual strain. This low-temperature annealing is desirably performed at a temperature in the range of 150 ° C. to 800 ° C. for 0.1 seconds to 24 hours. Note that heat treatment may be performed for a long time when the heat treatment temperature is low, and for a short time when the heat treatment temperature is high. If the heat treatment temperature is less than 50 ° C. or the heat treatment time is less than 0.1 seconds, there is a possibility that a sufficient strain relief effect may not be obtained. On the other hand, if the heat treatment temperature exceeds 800 ° C., recrystallization may occur. Further, if the heat treatment time exceeds 24 hours, only the cost increases. In addition, when finishing process S08 is not performed, low temperature annealing process S09 may be abbreviate | omitted.

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, the 0.2% proof stress is 300 MPa or more.
Moreover, when rolling is applied as a processing method, a copper alloy thin plate (strip material) for electronic / electric equipment having a thickness of about 0.05 to 1.0 mm 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 and electrical equipment according to the present embodiment configured as described above, Ni—P based precipitates or [Ni, (Fe, Co)] — P based precipitations from the parent phase mainly composed of α phase. And at least 10 Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates having an average particle size of 1 nm or more and 100 nm or less on average per 1 μm ^3. The number of Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates having a particle diameter exceeding 100 nm and less than 500 nm is 0.005 or more and 10 on average per 1 μm ^3. In addition, since the average grain size of the α phase crystal grains containing Cu, Zn and Sn is within the range of 0.1 to 50 μm, the stress relaxation resistance is uniform and reliable and sufficient. Excellent and high strength (proof strength) Bendability will be excellent.

  Furthermore, since the copper alloy for electronic and electrical equipment according to the present embodiment has a mechanical property of 0.2% proof stress of 300 MPa or more, it has a particularly high strength such as a movable conductive piece of an electromagnetic relay or a spring part of a terminal. Suitable for conductive parts that require More preferably, the 0.2% proof stress is 450 MPa or more.

Since the copper alloy thin plate for electronic / electric equipment according to the present embodiment is made of the above-mentioned copper alloy rolled sheet for electronic / electric equipment, it has excellent stress relaxation resistance, and is suitable for connectors, other terminals, and electromagnetic relays. It can be suitably used for a movable conductive piece, a lead frame, 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.
Furthermore, since the conductive member and terminal for electronic and electrical equipment according to the present embodiment are composed of the above-described copper alloy thin plate for electronic and electrical equipment, it is excellent in stress relaxation resistance, and with time or high temperature. Residual stress is difficult to relax in the environment.

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 and electrical equipment has a composition within the scope of the present invention, and further has a particle size. Of Ni—P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates in the range of 1 nm to 100 nm, the average number per 1 μm ³ , the range of particle diameters exceeding 100 nm and less than 500 nm The average number of Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates per 1 μm ³ , and the average particle diameter of α-phase crystal grains containing Cu, Zn and Sn are It suffices if it is set within the scope of the present invention.

  Hereinafter, the result of the confirmation experiment conducted to confirm the effect of the present invention will be 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, prepare the raw material consisting of Cu-40% Zn mother alloy and pure 99.99Mass% or more oxygen-free copper (ASTM B152 C10100), and was charged with this high-purity graphite crucible, a _{N 2} gas atmosphere It melt | dissolved using the electric furnace. Various additive elements were added into the molten copper alloy to melt the molten alloy having the composition shown in Tables 1, 2, and 3, and poured into a carbon mold to produce an ingot. The size of the ingot was about 30 mm thick × about 50 mm wide × about 200 mm long.
Subsequently, each ingot was subjected to water quenching as a homogenization treatment in an Ar gas atmosphere at a temperature described in Tables 4, 5, and 6 for a predetermined time (1 to 24 hours).

  Next, roughing and intermediate heat treatment were performed. Specifically, in the roughing, cold rolling was performed at a rolling rate of 50% or more so that the width direction of the ingot was the rolling direction. Thereafter, an intermediate heat treatment for recrystallization was carried out at the temperatures shown in Tables 4, 5, and 6 for 1 to 24 hours, followed by water quenching. Thereafter, the rolled material was cut, and surface grinding was performed to remove the oxide film.

Then, after carrying out cold rolling with a rolling rate of 50% or more as an intermediate process, the process of finishing heat treatment was repeated twice, and carried out for a predetermined time (1 second to 24 hours) at the temperatures shown in Tables 4, 5, and 6. did. In the case of a heat treatment time of less than 1 hour, the heat treatment was performed using a salt bath furnace. In addition, Example 16 and Comparative Example 105 were gradually quenched to 150 ° C. after finishing heat treatment at 1 ° C./hour, and then quenched with water. Next, finish rolling was carried out at the rolling rates shown in Tables 4, 5, and 6.
Finally, low temperature annealing was performed. Low-temperature annealing was carried out by water quenching after holding for a predetermined time (1 second to 24 hours) at the temperatures shown in Tables 4, 5, and 6. In the case of a heat treatment time of less than 1 hour, the heat treatment was performed using a salt bath furnace. Then, after cutting and surface polishing, a strip for characteristic evaluation having a thickness of 0.2 mm and a width of about 160 mm was produced.

  These strips for property evaluation were examined for electrical conductivity and mechanical properties (yield strength), as well as stress relaxation resistance properties, and further subjected to structure observation. The test method and measurement method for each evaluation item are as follows, and the results are shown in Tables 7, 8, and 9.

[Observation of crystal grain size]
Using a plane perpendicular to the rolling width direction, that is, a TD plane (Transverse direction) as an observation plane, the grain boundary and the crystal orientation difference distribution were measured as follows using an EBSD measuring apparatus and OIM analysis software.
After mechanical polishing using water-resistant abrasive paper and diamond abrasive grains, finish polishing was performed using a colloidal silica solution. 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. 5.3). ), The orientation difference of each crystal grain was analyzed with an electron beam acceleration voltage of 20 kV and a measurement area of 1000 μm ² or more at a measurement interval of 0.1 μm step. The CI value of each measurement point was calculated by the analysis software OIM, and those having a CI value of 0.1 or less were excluded from the analysis of the crystal grain size. As a result of two-dimensional cross-sectional observation, a crystal grain boundary map is created with a crystal grain boundary as a crystal grain boundary between measurement points where the orientation difference between two adjacent crystals is 15 ° or more, and the cutting method of JIS H 0501 In accordance with the above, draw 5 vertical and horizontal line segments at a time from the grain boundary map, count the number of crystal grains to be completely cut, and calculate the average value of the cut length as the average grain size. It was.

[Observation of precipitates]
About each strip for characteristic evaluation, using a transmission electron microscope (TEM: manufactured by Hitachi, H-800, HF-2200) and an EDX analyzer (manufactured by Noran, EDX analyzer SYSTEM SIX), precipitation was performed as follows. Object observation was performed.
After mechanical polishing using water-resistant abrasive paper and diamond abrasive grains from the front and back surfaces of the rolled material, a TEM observation sample was prepared by a twin jet method using an electrolytic solution. The TEM observation sample was produced from two places which entered 1/4 in the thickness direction from each of two places on the front and back surfaces of the rolled material.
Electron beam diffraction is performed on precipitates having a particle diameter of about 20 nm to 50 nm, and these precipitates are hexagonal crystals (space group: P-62m (189)) having a Fe ₂ P-based or Ni ₂ P-based crystal structure. Alternatively, it was confirmed to be a Co ₂ P-based or Fe ₂ P-based orthorhombic crystal (space group: P-nma (62)). Furthermore, as a result of analyzing the composition of the precipitate using EDX (energy dispersive X-ray spectroscopy), the precipitate contains at least one element selected from the group consisting of Fe, Co, and Ni and P. It was confirmed that it was contained, that is, a kind of [Ni, (Fe, Co)]-P-based precipitate already defined.

[Number of precipitates per 1 μm ³ ]
The number of precipitates per 1 μm ³ of precipitates having a particle diameter of 1 nm to 100 nm and precipitates having a particle diameter of more than 100 nm and 500 nm or less was calculated as follows.
In the observation of precipitates having a particle diameter of 1 nm or more and 100 nm or less, only the precipitates were binarized from a TEM photograph taken with a 150,000-fold field of view (about 0.5 μm ² ). An example of a TEM photograph and its binarized image are shown in FIG. From the binarized image, the image equivalent software “Win ROOF” was used to determine the equivalent circle diameter from the area of the precipitate, and this was used as the particle diameter.
In order to obtain the volume of the observation field, the sample film thickness was measured using a contamination method. In the contamination method, contamination was attached to a part of the sample, and the sample thickness t was determined from the increase ΔL in the length of the contamination when the sample was tilted by θ using the following equation.
t = ΔL / sin θ
The observation field volume was calculated by multiplying the thickness t thus determined and the observation field area. The number of precipitates was measured so that the observation field volume was 0.5 μm ³ or more for each sample collected from the front and back surfaces.

For observation of precipitates having a particle diameter exceeding 100 nm and not more than 500 nm, only the precipitates were binarized from a TEM photograph taken with a 15,000-fold field of view (about 50 μm ² ). An example of a TEM photograph and its binarized image are shown in FIG. From the binarized image, image analysis software “Win ROOF” was used to determine the equivalent circle diameter from the area of the precipitate, which was used as the particle diameter, and the sample film thickness was measured using the above-described contamination method. The number of precipitates was measured such that the observation field volume was 50 μm ³ or more for each of the samples collected from the front and back surfaces.

(Mechanical properties)
A No. 13B test piece defined in JIS Z 2201 was collected from the strip for characteristic evaluation, and Young's modulus E and 0.2% proof stress σ _0.2 were measured by the 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.

〔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.

[Stress relaxation resistance]
In the stress relaxation resistance test, a stress was applied by a method according to the Japan Copper and Brass Association Technical Standard JCBA-T309: 2004 cantilevered screw type, and the Zn content exceeded 2.0 mass% and was less than 15 mass% ( Samples having a Zn content of 15.0 mass% or more and 36.5 mass% or less after being held at a temperature of 150 ° C. for 500 hours with respect to “2-15 Zn evaluation” in Tables 7, 8, and 9) For Tables 7, 8 and 9, the value of “15-36.5Zn evaluation” was measured, and the residual stress ratio after holding at 120 ° C. for 500 hours was measured.
As a test method, test pieces (width 10 mm) were sampled in the direction perpendicular to the rolling direction from the front end portion, the central portion, and the rear end portion in the rolling direction of each strip for property evaluation, and the maximum surface of the test piece was obtained. The initial deflection displacement was set to 2 mm and the span length was adjusted so that the stress was 80% of the proof stress. The maximum surface stress is determined by the following equation.
Maximum surface stress (MPa) = 1.5 Etδ ₀ / L _s ²
However,
E: Young's modulus (MPa)
t: sample thickness (t = 0.20 mm)
δ ₀ : Initial deflection displacement (2 mm)
L _s : Span length (mm)
It is.
The residual stress rate was calculated from each test piece using the following formula.
Residual stress rate (%) = (1−δ _t / δ ₀ ) × 100
However,
δ _t : Permanent deflection displacement after holding at 120 ° C. for 500 h or after holding at 150 ° C. for 500 h (mm) −Permanent deflection displacement after holding for 24 h at room temperature (mm)
δ ₀ : Initial deflection displacement (mm)
It is.
With respect to the rolling direction, the average values of the residual stress ratios of the test pieces collected from the front end portion, the central portion, and the rear end portion were evaluated as ◯, and those having less than 80% were evaluated as x.

[Uniformity]
In the stress relaxation resistance test described above, uniform when the difference between the maximum value and the minimum value is within 5% of the residual stress rate of the test specimen taken from each of the front end, center and rear end in the rolling direction When the property was good, it was rated as x when it was higher than 5%.

[Bending workability]
Bending was performed in accordance with four test methods of JCBA (Japan Copper and Brass Association Technical Standard) T307-2007. A plurality of test pieces having a width of 10 mm and a length of 30 mm are sampled from the strip for characteristic evaluation so that the rolling direction and the longitudinal direction of the test piece are orthogonal to each other. A W bending test was performed using a jig.

  Tables 7, 8, and 9 show the results of the observation of each structure and the evaluation results.

In Comparative Example 101, the amount of Sn exceeded the range of the present invention, Ni and P were not added, and [Ni, (Fe, Co)]-P of 1 nm to 100 nm per 1 μm ³ Since the number of system precipitates was out of the range of the present invention, the stress relaxation resistance evaluation was “x” evaluation.
In Comparative Example 102, the number of [Ni, (Fe, Co)]-P-based precipitates of 1 nm or more and 100 nm or less per 1 μm ³ was outside the range of the present invention. "Evaluation. Furthermore, the bending workability was also evaluated as “×”.
In Comparative Example 103, Ni was not added, and the number of [Ni, (Fe, Co)]-P-based precipitates of 1 nm to 100 nm per 1 μm ³ was outside the scope of the present invention. The stress relaxation resistance evaluation was “x” evaluation.

In Comparative Example 104, the average number of Ni—P based precipitates and [Ni, (Fe, Co)] — P based precipitates exceeding 100 nm and less than 500 nm per 1 μm ³ was outside the scope of the present invention. The stress relaxation resistance evaluation and the uniformity evaluation were “x” evaluations.
In Comparative Example 105, the average number of Ni—P based precipitates and [Ni, (Fe, Co)] — P based precipitates exceeding 100 nm and less than 500 nm per 1 μm ³ was outside the scope of the present invention. The uniformity evaluation was an “x” evaluation.

On the other hand, as shown in Tables 7 and 8, not only the individual content of each alloy element is within the range defined by the present invention, but also the ratio of each alloy component to each other in the present invention. The average number of particles per 1 μm ³ of Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates having a particle diameter within the range of 1 nm to 100 nm. Contains an average number per 1 μm ³ of Ni-P-based precipitates or [Ni, (Fe, Co)]-P-based precipitates having a diameter exceeding 100 nm and less than 500 nm, Cu, Zn and Sn Invention Example No. in which the average grain size of the α-phase crystal grains is within the scope of the present invention. Nos. 1 to 31 are all excellent in stress relaxation resistance, and also excellent in proof stress, bending workability, and uniformity, and were confirmed to be sufficiently applicable to connectors and other terminals.

Claims (8)

Zn exceeds 2.0 mass% to 36.5 mass% or less, Sn ranges from 0.10 mass% to 0.90 mass%, Ni ranges from 0.15 mass% to less than 1.00 mass%, and P ranges from 0.005 mass% to 0.100 mass%. % Or less, with the balance consisting of Cu and inevitable impurities,
The ratio Ni / P between the Ni content and the P content is the atomic ratio,
3.0 <Ni / P <100.0
The filling,
And the ratio Sn / Ni between the Sn content and the Ni content is the atomic ratio,
0.10 <Sn / Ni <2.90
The filling,
Furthermore, Ni-P based precipitates containing Ni and P are included,
Particle size the Ni-P-based precipitates in a range of 1nm or 100nm or less 1 [mu] m ³ per average 10 or more, the Ni-P-based precipitates within the range of less than 500nm particle size beyond 100nm is 1 [mu] m The average particle size of α phase crystal grains containing Cu, Zn and Sn is 0.005 or more and 10 or less per ^{3 on} average, and is characterized by being in the range of 0.1 or more and 50 μm or less Copper alloy for electronic and electrical equipment. Zn exceeds 2.0 mass% to 36.5 mass% or less, Sn ranges from 0.10 mass% to 0.90 mass%, Ni ranges from 0.15 mass% to less than 1.00 mass%, and P ranges from 0.005 mass% to 0.100 mass%. % Or less,
Containing one or both of Fe of 0.001 mass% or more and less than 0.100 mass% and Co of 0.001 mass% or more and less than 0.100 mass%, with the balance consisting of Cu and inevitable impurities,
The ratio of the total content of Ni, Fe and Co (Ni + Fe + Co) to the content of P (Ni + Fe + Co) / P is the atomic ratio,
3.0 <(Ni + Fe + Co) / P <100.0
The filling,
And the ratio Sn / (Ni + Fe + Co) of the content of Sn and the total content of Ni, Fe and Co (Ni + Fe + Co) is an atomic ratio,
0.10 <Sn / (Ni + Fe + Co) <2.90
While satisfying
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 <1.500
The filling,
Furthermore, it has [Ni, (Fe, Co)]-P-based precipitates containing at least one element selected from the group consisting of Fe, Co, and Ni and P,
The [Ni, (Fe, Co)]-P-based precipitates having a particle diameter of 1 nm or more and 100 nm or less on average are 10 or more per 1 μm ³ , and the particle diameter is more than 100 nm and less than 500 nm. [Ni, (Fe, Co)]-P-based precipitates exist in an average of 0.005 or more and 10 or less per 1 μm ³ , and the average grain size of α-phase crystal grains containing Cu, Zn and Sn is A copper alloy for electronic and electrical equipment, characterized by being in the range of 0.1 to 50 μm.   A copper alloy for electronic / electric equipment comprising the rolled material of the copper alloy for electronic / electric equipment according to claim 1 or 2, wherein the thickness is in a range of 0.05 mm to 1.0 mm. Thin plate.   The copper alloy thin plate for electronic / electric equipment according to claim 3, wherein the surface is plated with Sn.   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.   5. A conductive component for electronic / electric equipment comprising the copper alloy thin plate for electronic / electric equipment according to claim 3 or 4.   A terminal comprising the copper alloy thin plate for electronic / electrical equipment according to claim 3 or 4.