JP7051029B1 - Copper alloy plate material, manufacturing method of copper alloy plate material and contact parts - Google Patents

Abstract

Provided is a copper alloy plate material or the like, which suppresses a decrease in strength due to an increase in temperature, has high strength at high temperatures, and has excellent conductivity. At least one of Ni and Co is contained in a total of 0.5% by mass or more and 5.0% by mass or less, and Si is contained in an amount of 0.10% by mass or more and 1.50% by mass or less, and Ni and Co are contained with respect to the Si content. A copper alloy plate having a total content mass ratio (Ni + Co) / Si of 2.00 or more and 6.00 or less and an alloy composition consisting of copper and unavoidable impurities as the balance, and Ni and Co in the matrix. A diffusion containing at least one of Ni and Co and Cu and Si as observed by a three-dimensional atom probe field ion microscope in the boundary region between the Si compound and the matrix, which contains a Si compound containing at least one of Ni and Si. It has a layer, and the average thickness of the diffusion layer is 0.5 nm or more and 5.0 nm or less.

Description

The present invention relates to a copper alloy plate material, a method for manufacturing a copper alloy plate material, and contact parts.

Copper alloy plates are used for electric / electronic devices such as smartphones, tablets, notebook PCs, action cameras, automobiles, industrial devices, and parts such as robots, for example, contact parts such as connectors.

As such a copper alloy plate material, for example, in Patent Document 1, in a Cu—Fe—P alloy, the interatomic distance of Fe and P measured by a three-dimensional atom probe electric field ion microscope is shortened, and Cu. A technique for producing a copper alloy plate material having excellent strength and heat resistance in heat treatment during production by increasing the aggregate density of Fe and P is disclosed.
Further, in Patent Document 2, in a Cu—Ni—Sn—P alloy, the interatomic distance of Ni and P measured by a three-dimensional atom probe field ion microscope is shortened, and an aggregate of Cu, Ni and P is obtained. A technique for producing a copper alloy plate material having excellent stress resistance relaxation characteristics by increasing the density is disclosed.
Further, in Patent Document 3, in a Cu—Ni—Co—Si based alloy, a copper alloy plate material that improves conductivity, stress relaxation resistance characteristics, and formability by controlling the component composition, spring limit value, and crystal orientation is used. The technology is disclosed.

Japanese Unexamined Patent Publication No. 2009-263690 Japanese Unexamined Patent Publication No. 2009-179864 Japanese Unexamined Patent Publication No. 2016-53220

Here, in recent years, with the increase in high-speed communication, high-speed power supply, increase in the number of sensors, etc., the internal circuit has increased in current and the amount of heat generated has also increased. Since the above-mentioned electric / electronic equipment, automobiles, industrial equipment, robots, etc. are continuously used for a certain period of time in a state of heat generation, their parts may be used at a high temperature. In particular, spring electrical contact components such as connectors tend to have high temperatures during high-speed communication and high-speed charging. If such parts are continuously used in a high temperature environment, the strength will be lower than the strength at room temperature (for example, 25 ° C) when new, and problems such as material breakage due to stress due to fitting will occur. There is a risk. In order to prevent this, it is desired that the strength decrease due to the temperature rise is suppressed and the strength at a high temperature (for example, 100 ° C.) is high.

On the other hand, the above-mentioned parts are required to have excellent conductivity.

However, with the conventional techniques such as Patent Documents 1 to 3, it is difficult to obtain a copper alloy plate material having high strength at high temperature and excellent conductivity by suppressing a decrease in strength due to a temperature rise. In Patent Documents 1 to 3, no attention is paid to the strength when used at a high temperature.

The present invention has been made in view of the above circumstances, and is a copper alloy plate material, a method for producing a copper alloy plate material, and copper, which suppresses a decrease in strength due to a temperature rise, has high strength at high temperatures, and has excellent conductivity. It is an object of the present invention to provide contact parts using an alloy plate material.

As a result of diligent studies, the present inventors have made a total of 0.5% by mass or more and 5.0% by mass or less of at least one of Ni and Co, and 0.10% by mass or more and 1 of Si in the copper alloy plate material. An alloy containing 5.5% by mass or less, having a mass ratio (Ni + Co) / Si of the total content of Ni and Co to the Si content of 2.0 or more and 6.0 or less, and the balance being copper and unavoidable impurities. A copper alloy plate having a composition, in which a Si compound containing at least one of Ni and Co and Si is contained in the matrix, and a three-dimensional atom probe electric field ion microscope is provided in the boundary region between the Si compound and the matrix. It has a diffusion layer containing at least one of Ni and Co and Cu and Si, and the average thickness of the diffusion layer is 0.5 nm or more and 5.0 nm or less, so that the strength decreases with increasing temperature. Suppressed, high strength at high temperature, and excellent conductivity, and such a copper alloy plate material is melt-cast into a copper alloy material having an alloy composition similar to the alloy composition of the copper alloy plate material [Step 1]. ], Homogenization [Step 2], Hot Rolling [Step 3], Face Milling [Step 4], First Cold Rolling [Step 5], First Temporary Heat Treatment [Step 6], Solution Heat Treatment [Step 7] , Second aging heat treatment [Step 8], second cold rolling [Step 9], and tempering annealing [10] in this order. In the first temporary aging heat treatment [Step 6], the temperature is 500 to 700 ° C. Hold for ~ 240 minutes, and in the solution heat treatment [Step 7], after the first temporary effect heat treatment [Step 6], the temperature is raised from room temperature, and the temperature is reached at 750 to 980 ° C. for 0.10 to 10 seconds before cooling. It was found that it can be manufactured by the above-mentioned manufacturing method, and the present invention was completed based on such knowledge.

That is, the gist structure of the present invention is as follows.
(1) A total of 0.5% by mass or more and 5.0% by mass or less of at least one of Ni and Co,
In addition, it contains Si in an amount of 0.10% by mass or more and 1.50% by mass or less.
Moreover, the mass ratio (Ni + Co) / Si of the total content of Ni and Co to the Si content is 2.00 or more and 6.00 or less.
A copper alloy plate having an alloy composition in which the balance is composed of copper and unavoidable impurities.
The matrix contains a Si compound containing at least one of Ni and Co and Si.
The boundary region between the Si compound and the matrix has a diffusion layer containing at least one of Ni and Co and Cu and Si as observed by a three-dimensional atom probe electric field ion microscope.
A copper alloy plate having an average thickness of 0.5 nm or more and 5.0 nm or less.
(2) The copper alloy plate material according to (1) above, wherein the alloy composition contains only Co among Ni and Co, and the Co content is 0.5% by mass or more and 5.0% by mass or less.
(3) The copper alloy plate material according to (1) above, wherein the alloy composition contains only Ni among Ni and Co, and the Ni content is 0.5% by mass or more and 5.0% by mass or less.
(4) The alloy composition contains both Ni and Co, the Ni content is 0.5% by mass or more and 4.5% by mass or less, and the Co content is 0.4% by mass or more and 2.5% by mass. % Or less, the copper alloy plate material according to (1) above.
(5) The alloy composition further contains at least one selected from the group consisting of Mg, Sn, Zn, P, Cr, Zr and Fe in a total amount of 0.1% by mass or more and 1.0% by mass or less. The copper alloy plate material according to any one of (1) to (4) above.
(6) The method for manufacturing a copper alloy plate according to any one of (1) to (5) above.
Melting casting [step 1], homogenization [step 2], hot rolling [step 3], face milling [step 4], and first One cold rolling [step 5], first temporary heat treatment [step 6], solution heat treatment [step 7], second aging heat treatment [step 8], second cold rolling [step 9], and tempering annealing [step 9]. 10] is applied in this order, and in the first temporary heat treatment [step 6], the temperature is maintained at 500 to 700 ° C. for 1 to 240 minutes.
The solution heat treatment [step 7] is characterized in that after the first temporary effect heat treatment [step 6], the temperature is raised from room temperature, held at an ultimate temperature of 750 to 980 ° C. for 0.10 to 10 seconds, and then cooled. Manufacturing method of copper alloy plate material.
(7) A contact component formed by using the copper alloy plate material according to any one of (1) to (5) above.

The copper alloy plate material of the present invention suppresses a decrease in strength due to an increase in temperature, has high strength at high temperatures, and is excellent in conductivity. Therefore, it is suitable as a copper alloy plate material for electrical / electronic equipment, automobiles, industrial equipment, and contact parts such as connectors in robots, which can be used at high temperatures.

FIG. 1 is a diagram showing an example of observation with a three-dimensional atom probe electric field ion microscope.

(1) Copper Alloy Plate Material Hereinafter, preferred embodiments of the copper alloy plate material of the present invention will be described in detail.
The copper alloy plate material according to the present invention contains at least one of Ni and Co in a total amount of 0.5% by mass or more and 5.0% by mass or less, and Si in an amount of 0.10% by mass or more and 1.50% by mass or less, and A copper alloy plate having an alloy composition in which the mass ratio (Ni + Co) / Si of the total content of Ni and Co to the Si content is 2.00 or more and 6.00 or less, and the balance is copper and unavoidable impurities. The matrix contains a Si compound containing at least one of Ni and Co and Si, and is observed by a three-dimensional atom probe field ion microscope in the boundary region between the Si compound and the matrix, and at least one of Ni and Co. It has a diffusion layer containing Cu and Si, and is characterized in that the average thickness of the diffusion layer is 0.5 nm or more and 5.0 nm or less.
Hereinafter, the alloy composition of the copper alloy plate material of the present invention, the Si compound contained in the copper alloy plate material, and the reasons for limiting the diffusion layer will be described.

<Alloy composition of copper alloy plate material>
[Ni and Co components]
The copper alloy plate material of the present invention contains at least one of Ni and Co in a total amount of 0.5% by mass or more and 5.0% by mass or less. When the total of Ni and Co is less than 0.5% by mass, the strength is lowered, and when it is higher than 5.0% by mass, the conductivity is lowered. The total content of Ni and Co is preferably 0.8% by mass or more from the viewpoint of strength, and preferably 4.0% by mass or less from the viewpoint of conductivity. The total content of Ni and Co is more preferably 1.0% by mass or more and 3.5% by mass or less.
When only Co is contained among Ni and Co, the Co content is preferably 0.5% by mass or more and 5.0% by mass or less.
When only Ni is contained among Ni and Co, the Ni content is preferably 0.5% by mass or more and 5.0% by mass or less.
When both Ni and Co are contained, the Ni content is 0.5% by mass or more and 4.5% by mass or less, and the Co content is 0.4% by mass or more and 2.5% by mass or less. Is preferable.
It should be noted that the content of Co in an amount of 0.4% by mass or more has the effect of increasing the conductivity as compared with the case of Ni alone, but if it exceeds 2.0% by mass, the conductivity may decrease conversely. The Co content is preferably 0.5% by mass or more and 2.0% by mass or less.

[Si component]
The copper alloy plate material of the present invention contains Si in an amount of 0.10% by mass or more and 1.50% by mass or less. When the Si content is less than 0.10% by mass, the strength is lowered. If it is higher than 1.50% by mass, the conductivity is lowered, coarse crystallization is likely to occur in the ingot, and it remains as an unsolid solution after the solution heat treatment, and is the starting point of cracks during bending. It is easy to become. The Si content is preferably 1.25% by mass or less, more preferably 1.10% by mass or less, from the viewpoint of conductivity.

[(Ni + Co) / Si ratio]
In the copper alloy plate material of the present invention, the mass ratio of the total content of Ni and Co to the Si content, that is, the (Ni + Co) / Si ratio is 2.00 or more and 6.00 or less. When the (Ni + Co) / Si ratio is less than 2.00, Si is excessively present with respect to Ni and Co, the residual amount of Si in the matrix phase increases during the aging heat treatment, and the conductivity decreases. When the (Ni + Co) / Si ratio is higher than 6.00, the residual amount of Ni and Co increases, and the conductivity decreases. From the viewpoint of conductivity, it is preferably 3.00 to 5.00, more preferably 3.30 to 4.70.

[Arbitrary additive component]
The copper alloy plate material of the present invention further contains at least one selected from the group consisting of Mg, Sn, Zn, P, Cr, Zr and Fe in an amount of 0.1% by mass or more and 1.0% by mass or less in total. May be.

(Mg)
While Mg has the effect of improving the strength at high temperatures, it tends to lower the conductivity. Therefore, the content of Mg is preferably 0.1% by mass or more and 0.3% by mass.

(Sn)
While Sn has the effect of improving the strength at high temperatures, it tends to lower the conductivity. Therefore, the Sn content is preferably 0.1% by mass or more and 0.3% by mass or less.

(Zn)
Zn has an effect of improving Sn plating property and migration characteristics, but tends to lower the conductivity. Therefore, the Zn content is preferably 0.1% by mass or more and 0.5% by mass or less. ..

(P)
P has the effect of suppressing the precipitation of Si compounds on the grain boundaries and increasing the strength, but tends to decrease the conductivity, so the content of P is 0.1% by mass or more and 0.3% by mass. % Or less is preferable.

(Cr)
Cr has the effect of suppressing the coarsening of crystal grains during solution heat treatment, but it tends to generate coarse crystal grains during casting and tends to create crack origins, so the Cr content is 0. It is preferably 1% by mass or more and 0.3% by mass or less.

(Zr)
Zr has the effect of suppressing the coarsening of crystal grains during solution heat treatment, but it tends to generate coarse crystal grains during casting and tends to create crack origins, so the Zr content is 0. It is preferably 1% by mass or more and 0.2% by mass.

(Fe)
Fe has the effect of suppressing the coarsening of crystal grains during solution heat treatment, but coarse crystallized products are likely to be generated during casting, and crack origins are likely to be formed. Therefore, the Fe content is 0.1% by mass. It is preferably 0.2% by mass or less.

[Remaining: Copper and unavoidable impurities]
Except for the above-mentioned essential components and optional additives, the balance consists of Cu (copper) and unavoidable impurities. The "unavoidable impurities" referred to here are generally copper-based products that are present in raw materials or are inevitably mixed in the manufacturing process, and are originally unnecessary, but are in trace amounts. It is an acceptable impurity because it does not affect the properties of copper-based products. Examples of the components listed as unavoidable impurities include non-metal elements such as sulfur (S) and oxygen (O) and metal elements such as aluminum (Al) and antimony (Sb). The upper limit of the content of these components may be 0.05% by mass for each of the above components and 0.20% by mass for the total amount of the above components.

<Si compound>
The copper alloy plate material of the present invention contains a Si compound in the matrix phase.
The Si compound is a compound containing at least one of Ni and Co and Si. The Si compound may contain other elements contained in the copper alloy plate material in addition to Ni, Co and Si, and may contain, for example, Cu, Mg, Sn, Zn, P, Cr, Zr and Fe. good.

The Si compound is a precipitate formed by precipitating during the production of a copper alloy plate material. The Si compound is, for example, precipitated and formed in the first temporary heat treatment [step 6], and then undergoes solution heat treatment [step 7], second aging heat treatment [step 8], and the like to finally produce a copper alloy plate material. include.

<Diffusion layer>
The copper alloy plate material of the present invention has a diffusion layer containing at least one of Ni and Co and Cu and Si, which is observed by a three-dimensional atom probe field ion microscope in the boundary region between the Si compound and the matrix. The average thickness of the diffusion layer is 0.5 nm or more and 5.0 nm or less. The diffusion layer is defined as a region in which the concentration of Cu is 20 at% or more and 90 at% or less, which is observed with a three-dimensional atom probe field ion microscope for the copper alloy plate material. Details of the three-dimensional atom probe electric field ion microscope will be described later.

The present inventors have the above alloy composition, and the average thickness of the diffusion layer observed by the three-dimensional atom probe field ion microscope in the boundary region between the Si compound and the matrix is set to 0.5 nm or more and 5 nm or less. By doing so, it has been found that a copper alloy plate material having high strength at high temperature and excellent conductivity can be obtained by suppressing a decrease in strength due to an increase in temperature.

Effect of phase transformation of copper alloy on changes in strength in the range of operating temperature of electrical / electronic equipment, automobiles, industrial equipment, robots, etc., specifically room temperature (for example, 25 ° C) to high temperature (for example, 100 ° C). Is almost negligible, and it is considered that the change in strength is affected by the mobility of dislocations, which is a thermal activation phenomenon. Therefore, in order to suppress the decrease in strength due to temperature rise and increase the strength at high temperature, it is effective to inhibit dislocation movement by increasing the number of second phase particles such as solid solution elements and precipitates. It is believed that there is. On the other hand, if the amount of the solute element added is simply increased in order to increase the amount of the solid solution atom or the second phase, there arises a problem that the conductivity decreases. Therefore, the present inventors consider that a method of not increasing the amount of added elements is required in order to suppress the decrease in strength due to the temperature rise, increase the strength at high temperature, and improve the conductivity. By forming a diffusion layer of a predetermined thickness at the interface between the Si compound, which is a precipitate, and the parent phase, the decrease in strength due to an increase in temperature is suppressed, the strength at high temperatures is high, and copper has excellent conductivity. It was found that it would be an alloy plate material. Since the copper alloy plate has high strength at high temperature, it also has high strength at room temperature.

The diffusion layer is a state in which Ni atoms, Co atoms, and Si atoms are locally present in a high concentration in the Cu matrix phase, and this diffusion layer suppresses the movement of dislocations. It is presumed that this is one of the reasons why the copper alloy plate material has high strength at high temperature and excellent conductivity by suppressing the decrease in strength due to the temperature rise.

The average thickness of the diffusion layer needs to be 0.5 nm or more and 5.0 nm or less. When the thickness of the diffusion layer is smaller than 0.5 nm, the strength is greatly reduced as the temperature rises, or the strength at a high temperature is lowered. When the thickness of the diffusion layer is larger than 5.0 nm, the amount of solid solution increases and the conductivity decreases. The thickness of the diffusion layer is preferably 1.0 nm or more and 4.0 nm or less, and more preferably 2.0 nm or more and 3.0 nm or less.

(3D atom probe electric field ion microscope)
The three-dimensional atom probe method (3DAP method) is an analysis method capable of three-dimensional composition analysis of nanoprecipitates and clusters in metals and semiconductors. The principle is as follows.
A needle-shaped sample having a tip of about 100 nm is prepared, carried into a 3DAP device (three-dimensional atom probe electric field ion microscope), and then a high voltage is applied in a pulse to evaporate the electric field one atom at a time from the tip of the sample. Further, by irradiating the tip of the needle with a pulsed laser having a specific wavelength to assist electric field evaporation, it is possible to reduce the probability of sample destruction, improve the mass resolution, and measure semiconductors and insulators. The two-dimensional position detector detects the flight time and position measurement of the ions that have been electro-evaporated by the pulse voltage and laser irradiation, and measures the two-dimensional coordinate position of each ion. By measuring the time from the time of evaporation at the tip of the needle to the time of reaching the detector, analysis as time-of-flight mass spectrometry is also possible, so the reached ion species can be identified. Since laser irradiation is repeated to obtain information on the two-dimensional coordinate position of the ion and information on the depth direction of the sample, three-dimensional composition information can be obtained by performing data analysis considering the shape of the tip of the needle. Is possible.

As the 3DAP device, for example, EIKOS-X manufactured by CAMECA can be used.
The thickness of the diffusion layer is determined by observing from the matrix to the Si compound and using a proxygram, which is a concentration profile of each component (Cu, Si, Ni, Co, etc.) of the obtained copper alloy plate material. If there is unevenness in the boundary region between the Si compound that is the second phase and the parent phase, creating a one-dimensional concentration profile across the boundary region will superimpose the effects of the unevenness and define an accurate diffusion layer. I can't. For this reason, a proxygram based on the equiconcentration plane of a specific element is used. The proxygram is a one-dimensional concentration profile in which the concentration is calculated in the direction perpendicular to the plane of the equal concentration of a specific element as a reference. IVAS, which is a 3D atom probe software provided by CAMECA, can be used for the calculation of the proxygram. For example, FIG. 1 is a proxygram based on an equal concentration surface having a Ni concentration of 5 at%. FIG. 1 is an example of observation with a three-dimensional atom probe field ion microscope of a copper alloy plate having an alloy composition of Ni: 2.3% by mass and Si: 0.55% by mass with the balance of Cu. From this proxygram, it can be seen that in the copper alloy plate material of the present invention, Co, Ni, Cu and the like are diffused at the interface between the Si compound and the parent phase.
In the proxygram, as shown in FIG. 1, the region where the Cu concentration is 20 at% or more and 90 at% or less is the diffusion layer, and the thickness of the diffusion layer is the region where the Cu concentration is 20 at% or more and 90 at% or less. , The length in the horizontal axis (distance) direction.

The average thickness of the diffusion layer was sampled at five locations at even intervals in the direction perpendicular to the rolling direction in the copper alloy plate material, and the diffusion layer obtained from the proxygram measured for each sample (sample). It is the average value of the thickness of.

As described above, the copper alloy plate material of the present invention suppresses a decrease in strength due to an increase in temperature, has high strength at high temperatures, and has excellent conductivity. Therefore, parts such as electric / electronic equipment, automobiles, industrial equipment, and robots formed by using the copper alloy plate material of the present invention are highly reliable in terms of strength and conductivity. For example, even when the operating temperature is from room temperature to high temperature, there is little change in strength, the strength exceeds a certain level, and the conductivity is excellent, so that the component is highly reliable. In particular, even a spring electric contact component such as a connector whose terminal tends to become hot during high-speed communication or high-speed charging can be highly reliable by using the copper alloy plate material of the present invention.

The tensile strength of the copper alloy plate material at 100 ° C. is, for example, 500 MPa or more. The tensile strength of the copper alloy plate material at 100 ° C. can be 600 MPa or more or 690 MPa or more.
Further, since the copper alloy plate material of the present invention has high strength at high temperature, it also has high strength at room temperature. The tensile strength of the copper alloy plate material at 25 ° C. is, for example, 500 MPa or more, and usually 505 MPa or more.

In the copper alloy plate material of the present invention, the decrease in strength due to temperature rise is suppressed, and the difference between the strength at room temperature and the strength at high temperature, for example, the difference between the tensile strength at 25 ° C. and the tensile strength at 100 ° C. is 100 MPa or less. , 70 MPa or less, 55 MPa or less, or 35 MPa or less.
For example, when the tensile strength of the copper alloy plate material at 25 ° C. is 500 MPa or more and less than 600 MPa, the difference between the tensile strength at 25 ° C. and the tensile strength at 100 ° C. is 100 MPa or less, preferably 70 MPa or less, more preferably. Is 55 MPa or less.
When the tensile strength of the copper alloy plate material at 25 ° C. is 600 MPa or more and less than 700 MPa, the difference between the tensile strength at 25 ° C. and the tensile strength at 100 ° C. is 100 MPa or less, preferably 70 MPa or less, and more preferably 55 MPa. It is as follows.
When the tensile strength of the copper alloy plate material at 25 ° C. is 700 MPa or more and less than 800 MPa, the difference between the tensile strength at 25 ° C. and the tensile strength at 100 ° C. is 100 MPa or less, preferably 90 MPa or less, and more preferably 70 MPa. It is less than or equal to, more preferably 55 MPa or less, and particularly preferably 35 MPa.
When the tensile strength of the copper alloy plate material at 25 ° C. is 800 MPa or more and less than 900 MPa, the difference between the tensile strength at 25 ° C. and the tensile strength at 100 ° C. is 100 MPa or less, preferably 95 MPa or less, and more preferably 55 MPa. It is as follows.
The tensile strength of the copper alloy plate material in the present specification can be measured based on JIS Z 2241: 2011, for example, using a JIS 13B test piece.

The conductivity of the copper alloy plate material of the present invention is, for example, 45% IACS or more, and may be 50% IACS or more or 55% IACS or more.
The conductivity of the copper alloy plate material in the present specification is calculated by measuring the specific resistance by the 4-terminal method in a constant temperature bath kept at 20 ° C. (± 0.5 ° C.), for example, when the distance between terminals is 100 mm. can do.

The copper alloy plate material of the present invention is also excellent in basic bending workability required for connectors and the like. On the other hand, in Patent Document 1 and Patent Document 2, in order to increase the strength and conductivity, the solid solution to the matrix is small, and the strength largely depends on the dislocation strengthening by cold working of 60% or more. Therefore, it is presumed that the copper alloy plates of Patent Document 1 and Patent Document 2 sacrifice the basic bending workability required for the connector.

The diffusion layer may contain other elements contained in the copper alloy plate material in addition to Ni, Co, Cu and Si, and may contain, for example, Mg, Sn, Zn, P, Cr, Zr and Fe. May be good.

(2) Method for Manufacturing Copper Alloy Plate Material A method for producing a copper alloy plate material according to the above embodiment of the present invention will be described in detail. In this manufacturing method, melt casting [step 1], homogenization [step 2], hot rolling [step 3], and surface milling [step 1] are performed on a copper alloy material having an alloy composition similar to that of the copper alloy plate. 4], first cold rolling [step 5], first temporary heat treatment [step 6], solution heat treatment [step 7], second aging heat treatment [step 8], second cold rolling [step 9], and The tempering and annealing [10] is performed in this order, and the first temporary heat treatment [step 6] is held at a temperature of 500 to 700 ° C. for 1 to 240 minutes, and the solution heat treatment [step 7] is the first temporary heat treatment [step 6]. ] Later, the temperature is raised from room temperature, and the temperature is maintained at an reached temperature of 750 to 980 ° C. for 0.10 to 10 seconds before cooling. Hereinafter, each step will be described.

<Dissolution casting [Step 1]>
In the melt casting step [step 1], an alloy component is melted in a high frequency melting furnace in the atmosphere, and the alloy component is cast to produce an ingot having a predetermined shape (for example, thickness 30 mm, width 100 mm, length 150 mm).

<Homogenization [Step 2]>
In the homogenization step [step 2], the homogenization heat treatment is performed by heating in the atmosphere or in an inert gas atmosphere at a predetermined temperature (for example, 1000 ° C.) for about 1 hour.

<Hot rolling [process 3]>
The hot rolling step [step 3] is performed immediately after the homogenization heat treatment, and is cooled immediately after the plate thickness is set to a predetermined value (for example, 10 mm).

<Surface cutting [process 4]>
In the face-cutting step [step 4], a face-cutting of a predetermined thickness (for example, about 1 mm to 2 mm) is performed from the surface of the hot-rolled plate to remove the oxide layer.

<First cold rolling [process 5]>
In the first cold rolling step [step 5], cold rolling is performed to, for example, 0.25 mm to 1 mm.

<First temporary heat treatment [step 6]>
In the first temporary heat treatment [step 6], the temperature is maintained at 500 to 700 ° C. for 1 to 240 minutes. After holding at a temperature of 500 to 700 ° C. for 1 to 240 minutes, the mixture is cooled to room temperature.
In the matrix of the first cold-rolled sheet obtained by the first cold rolling [step 5] by the first temporary heat treatment [step 6], a Si compound having an average size of 50 nm or more and 120 nm or less and containing Si is contained. , Precipitated and formed. When the temperature is less than 500 ° C., the average size of the precipitated Si compound becomes less than 50 nm, and homogenization by solidification and diffusion of Ni, Co and Si progresses in the solution heat treatment [step 7], and the second aging heat treatment [ In step 9], a Si compound having a narrow diffusion layer is likely to be produced, and the average thickness of the diffusion layer of the produced copper alloy plate becomes thin. Further, when the temperature exceeds 700 ° C., the average size of the Si compound becomes larger than 120 nm, the unsolidified Si compound in the solution heat treatment [step 7] increases, and the aging strength decreases. By performing the solution heat treatment [step 7] after the first temporary heat treatment [step 6] under appropriate conditions, even if the Si compound is once solid-dissolved by the solution heat treatment [step 7], the second aging heat treatment [step 9] is performed. ] It is considered that the precipitation state with wide diffusion was formed at times, the decrease in strength due to the temperature rise could be suppressed, and the difference between the room temperature strength and the high temperature strength could be reduced. On the other hand, conventionally, for example, Patent Document 3 does not pay attention to controlling the diffusion layer by the precipitation state before the solution heat treatment, and in the pre-annealing before the solution heat treatment, pays attention to the softening of the material and heat-treats for a short time. It is considered that an appropriate precipitation state cannot be created because of the heat treatment, and a precipitation state having a diffusion layer cannot be created.

For the average size of the Si compound, the cross section including the rolling parallel direction and the plate thickness direction is observed by TEM (Transmission Electron Microscope), and each Si compound observed from the obtained bright field image connects two outer edges. The average value of the longest straight line and the shortest straight line.
The Si compound precipitated and formed in the matrix of the first cold-rolled sheet obtained by the first cold rolling [step 5] by the first temporary heat treatment [step 6] is subjected to the solution heat treatment [step 7]. Since it undergoes the second aging heat treatment [step 8] and the like, the average size and the like are often different from those of the Si compound contained in the finally produced copper alloy plate material.

<Solution heat treatment [step 7]>
In the solution heat treatment [step 7], after the first temporary effect heat treatment [step 6], the temperature is raised from room temperature, held at an ultimate temperature of 750 to 980 ° C. for 0.10 to 10 seconds, and then cooled.
The solution heat treatment [step 7] dissolves the second phase particles (Si compound) produced by the first temporary effect heat treatment [step 6], but if the temperature is lower than 750 ° C., the solid dissolution does not proceed. Since it becomes difficult to form the diffusion layer in the second aging heat treatment [step 9], the average thickness of the diffusion layer becomes thin. When the temperature is higher than 980 ° C., the homogenization by diffusion progresses, and it becomes difficult to form the diffusion layer, so that the average thickness of the diffusion layer becomes thin. When the holding time is longer than 10 seconds, the solid solution atom is diffused and homogenized, and the diffusion layer precipitated and formed in the second aging heat treatment [step 8] becomes thin. If it is less than 0.10 seconds, the diffusion layer becomes thick. The holding time is preferably 1 to 5 seconds, more preferably 1 to 2 seconds.

In the solution heat treatment [step 7], the temperature rising rate is preferably 30 ° C./sec or more. If it is less than 30 ° C./sec, precipitates may grow during the temperature rise and the average thickness of the diffusion layer may become thin. The upper limit of the temperature rising rate is preferably 200 ° C./sec or less from the viewpoint of controlling the ultimate temperature. The cooling rate is preferably 50 ° C./sec or higher. If it is less than 50 ° C./sec, cooling from a high temperature may generate coarse precipitates and reduce the average thickness of the diffusion layer.

<Second aging heat treatment [process 8]>
The second aging heat treatment [step 8] is performed after the solution heat treatment [step 7].
As the second aging heat treatment [step 8], it is preferable to adopt a condition of holding the heat treatment at a temperature of 450 to 500 ° C. for about 3 to 5 hours, for example.

If necessary, additional cold rolling [step 11] may be further performed between the solution heat treatment [step 7] and the second aging heat treatment [step 8].
In the additional cold rolling [step 11], for example, cold rolling with a rolling processing ratio of about 80% or less is performed to make the thickness about 0.1 mm to 0.4 mm. The rolling processing ratio (%) is a value obtained by (plate thickness before rolling (mm) -plate thickness after rolling (mm)) / plate thickness before rolling (mm) × 100.

<Second cold rolling [process 9]>
In the second cold rolling [step 9], for example, cold rolling is performed to a thickness of about 0.09 to 0.36 mm.

<Temperature annealing [10]>
The temper annealing [10] is a step for reducing the anisotropy of mechanical properties including elongation. For example, heat treatment is performed in a salt bath at a temperature of about 400 ° C. for about 15 seconds to 1 minute. conduct.

The copper alloy plate material of the present invention is extremely useful as a material for forming contact parts such as connectors.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, but includes all aspects included in the concept of the present invention and claims, and varies within the scope of the present invention. Can be modified to.

Next, in order to further clarify the effect of the present invention, Examples and Comparative Examples will be described, but the present invention is not limited to these Examples.

(Examples 1 to 23 and Comparative Examples 1 to 8)
The alloy components shown in Tables 1 and 2 were melted in an atmosphere in a high-frequency melting furnace and cast by a mold to obtain ingots having a thickness of 30 mm, a width of 100 mm and a length of 150 mm (melting casting). [Step 1]). Next, after homogenization [step 2] at 1000 ° C. for 1 hour in the atmosphere, hot rolling [step 3] was carried out, and the hot-rolled plate having a thickness of 10 mm was immediately cooled. Next, 1 mm was surface-cut from the surface in the face-cutting [step 4] to remove the oxide film, and then the thickness was 0.4 mm in the first cold rolling [step 5]. Next, in the first temporary heat treatment [step 6], the heat treatment was performed at the temperatures and times shown in Tables 3 and 4 under an argon atmosphere, and then the mixture was cooled to room temperature. In both Examples and Comparative Examples, the Si compound was precipitated in the matrix of the first cold-rolled sheet obtained by the first cold rolling [step 5] by the first temporary heat treatment [step 6]. ..
Next, in the solution heat treatment [step 7], the temperature was raised from room temperature, the heat treatment was performed at the reached temperature and the holding time shown in Tables 3 and 4, and the mixture was immediately cooled with water. Next, the thickness was made 0.1 to 0.38 mm by additional cold rolling [step 11]. In Example 17, the additional cold rolling [step 11] was not performed. Next, in the second aging heat treatment [step 8], the heat treatment was performed at the temperatures and times shown in Tables 3 and 4 under an argon atmosphere. Next, in the second cold rolling [step 9], the thickness was 0.09 to 0.36 mm. Finally, in the temper annealing [step 10], heat treatment was performed at 400 ° C. for 30 seconds in a salt bath. From the above, a copper alloy plate material was produced.

By the following method, the average size of the Si compound formed by the first temporary heat treatment [Step 6], the average thickness of the diffusion layer, the tensile strength at 25 ° C. and 100 ° C., and the conductivity were determined. The results are shown in Tables 1 to 4.

[Average size of Si compound]
The Si compound precipitated and formed by the first temporary heat treatment [step 6] is subjected to the following method.
The average size of the Si compound was determined.
For the copper alloy plate material cooled to room temperature in the first temporary heat treatment [step 6], a square region having a rolling parallel direction dimension and a plate thickness dimension of 100 μm was observed by TEM in a cross section including the rolling parallel direction and the plate thickness direction. For each Si compound observed from the obtained bright field image, the average value of the longest straight line and the shortest straight line connecting the two outer edges was defined as the average size of the Si compound.

[Average thickness of diffusion layer]
(Preparation of sample)
A FIB (Focused Ion Beam) was used to prepare a needle-shaped sample for observation with a three-dimensional atom probe field ion microscope. For the preparation of the needle-shaped sample by FIB, Helios G4 manufactured by FEI was used.
A small sample of several μm was extracted from the copper alloy plate by the lift-out method, and then the sample was adhered to the support base. Next, the annular processing region was irradiated with a Ga ion beam having an acceleration voltage of 30 kV to form a needle shape. When the sample is scraped with a 30 kV Ga ion beam, a damaged layer of several tens of nm is formed on the irradiated surface. Therefore, by removing this damaged layer with a 5 kV Ga ion beam, which is a low acceleration, about 200 nm is finally formed. Needle-shaped sample was obtained.
In the copper alloy plate material, sampling was performed at 5 points at equal intervals in the direction perpendicular to the rolling direction to obtain 5 needle-shaped samples.

(Conditions for 3D atom probe electric field ion microscope)
As a three-dimensional atom probe electric field ion microscope (3DAP device), EIKOS-X manufactured by CAMECA was used. The sample was cooled to 50 K and measured. The wavelength of the irradiated laser was 532 nm, and the energy of the laser pulse was 20 nJ. The voltage applied to the needle was 1 to 5 kV.
In each needle-shaped sample, three Si compounds were selected and observed from the parent phase to the Si compound.

(Calculation of average thickness of diffusion layer)
The thickness of the diffusion layer was determined using a proxygram. For the calculation of the proxygram, IVAS, which is the software of the three-dimensional atom probe provided by CAMECA, was used.
Examples 1 to 3, 10 and Comparative Example 4 containing only Ni among Ni and Co were proxy grams based on an equal concentration surface having a Ni concentration of 5 at%. Further, Examples 7 to 9 and 13 containing only Co among Ni and Co were used as proxy grams based on an equal concentration surface having a Co concentration of 5 at%. Examples 4 to 6, 11, 12, 14 to 23 and Comparative Examples 1 to 3, 5 to 11 containing both Ni and Co were proxy grams based on an equal concentration surface having a Co concentration of 5 at%.
In this proxygram, the length in the horizontal axis direction of the region where the Cu concentration is 20 at% or more and 90 at% or less is determined as the thickness of the diffusion layer. The average value of the thickness of the diffusion layer was calculated by averaging the thicknesses of a total of 15 diffusion layers obtained for 3 Si compounds in each of the 5 needle-shaped samples.

[Tensile strength]
The tensile strength of the copper alloy plate was measured by performing a tensile test in the atmosphere at room temperature (25 ° C.) and high temperature (100 ° C.) based on JIS Z 2241: 2011 using a JIS 13B test piece.

[conductivity]
The conductivity of the copper alloy plate material was calculated by measuring the specific resistance by the 4-terminal method in a constant temperature bath kept at 20 ° C. (± 0.5 ° C.) with the distance between terminals set to 100 mm.

[evaluation]
Those having a tensile strength of 500 MPa or more at 100 ° C., a difference between the tensile strength at 25 ° C. and the tensile strength at 100 ° C. of 100 MPa or less, and a conductivity of 45% IACS or more were accepted.

From the results of Tables 1 to 4, all of the copper alloy plates of Examples 1 to 23 have an alloy composition within the range of the present invention, and a three-dimensional atom probe electric field ion is formed in the boundary region between the Si compound and the matrix. Since the average thickness of the diffusion layer observed by a microscope is 0.5 nm or more and 5.0 nm or less, the difference in tensile strength between 25 ° C and 100 ° C is as small as 100 MPa or less, and the tensile strength at 100 ° C is 500 MPa or more. It was high and the conductivity was as high as 45% IACS or more.

On the other hand, in Comparative Example 1 in which the solution heat treatment temperature is low and Comparative Example 2 in which the solution heat treatment temperature is high, the average thickness of the diffusion layer is less than 0.5 nm, and the difference in tensile strength between 25 ° C and 100 ° C is large. , The tensile strength at 100 ° C. was low. In Comparative Example 3 in which the holding time of the solution heat treatment was long, the average thickness of the diffusion layer was less than 0.5 nm, and the difference in tensile strength between 25 ° C. and 100 ° C. was large. In Comparative Example 4, in which the total amount of Ni and Co was small, the tensile strength at 100 ° C. was low. Comparative Example 5 having a low (Ni + Co) / Si ratio had a low conductivity. Comparative Example 6 having a high (Ni + Co) / Si ratio had a low conductivity. In Comparative Example 7 in which the first-time treatment time is long and the average size of the Si compound precipitated and formed by the first-time treatment is large, the average thickness of the diffusion layer is less than 0.5 nm, and the tensile strength between 25 ° C and 100 ° C is reached. The difference in strength was large, and the tensile strength at 100 ° C. was low. In Comparative Example 8 in which the temperature of the first-time treatment was low and the average size of the Si compound precipitated and formed by the first-time treatment was small, the average thickness of the diffusion layer was 0.5 nm, probably because homogenization was advanced by the solution treatment. It became less than, and the difference in tensile strength between 25 ° C. and 100 ° C. was large. Comparative Example 9 having a large total amount of Ni and Co and Comparative Example 10 having a large amount of Si had low conductivity. In Comparative Example 11 in which the holding time of the solution heat treatment was short, the average thickness of the diffusion layer was more than 5.0 nm, and the conductivity was low.

Claims (7)

At least one of Ni and Co in total 0.5% by mass or more and 5.0% by mass or less,
In addition, it contains Si in an amount of 0.10% by mass or more and 1.50% by mass or less.
Moreover, the mass ratio (Ni + Co) / Si of the total content of Ni and Co to the Si content is 2.00 or more and 6.00 or less.
A copper alloy plate having an alloy composition in which the balance is composed of copper and unavoidable impurities.
The matrix contains a Si compound containing at least one of Ni and Co and Si.
The boundary region between the Si compound and the matrix has a diffusion layer containing at least one of Ni and Co and Cu and Si as observed by a three-dimensional atom probe electric field ion microscope.
A copper alloy plate having an average thickness of 0.5 nm or more and 5.0 nm or less. The alloy composition contains only Co among Ni and Co, and contains only Co.
The copper alloy plate material according to claim 1, wherein the Co content is 0.5% by mass or more and 5.0% by mass or less. The alloy composition contains only Ni among Ni and Co, and contains only Ni.
The copper alloy plate material according to claim 1, wherein the Ni content is 0.5% by mass or more and 5.0% by mass or less. The alloy composition contains both Ni and Co and contains.
The Ni content is 0.5% by mass or more and 4.5% by mass or less.
The copper alloy plate material according to claim 1, wherein the Co content is 0.4% by mass or more and 2.5% by mass or less. The alloy composition further contains at least one selected from the group consisting of Mg, Sn, Zn, P, Cr, Zr and Fe in a total amount of 0.1% by mass or more and 1.0% by mass or less. The copper alloy plate material according to any one of 4 to 4. The method for manufacturing a copper alloy plate according to any one of claims 1 to 5.
Melting casting [step 1], homogenization [step 2], hot rolling [step 3], face milling [step 4], and first One cold rolling [step 5], first temporary heat treatment [step 6], solution heat treatment [step 7], second aging heat treatment [step 8], second cold rolling [step 9], and tempering annealing [step 9]. 10] is applied in this order,
In the first temporary heat treatment [step 6], the temperature was maintained at 500 to 700 ° C. for 1 to 240 minutes.
In the solution heat treatment [step 7], after the first temporary effect heat treatment [step 6], the temperature is raised from room temperature.
A method for producing a copper alloy plate, which comprises holding at an ultimate temperature of 750 to 980 ° C. for 0.10 to 10 seconds and then cooling. A contact component formed by using the copper alloy plate material according to any one of claims 1 to 5.

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