JP5045783B2 - Copper alloy for electronic equipment, method for producing copper alloy for electronic equipment, and rolled copper alloy material for electronic equipment - Google Patents

Description

  The present invention relates to a copper alloy for electronic devices suitable for electronic and electrical parts such as terminals, connectors and relays, a method for producing a copper alloy for electronic devices, and a rolled copper alloy material for electronic devices.

2. Description of the Related Art Conventionally, along with miniaturization of electronic devices and electrical devices, electronic electrical components such as terminals, connectors and relays used in these electronic devices and electrical devices have been miniaturized and thinned. For this reason, a copper alloy having excellent spring properties, strength, and conductivity is required as a material constituting the electronic / electrical component. In particular, as described in Non-Patent Document 1, it is desirable that the copper alloy used as an electronic component such as a terminal, a connector, or a relay has a high yield strength and a low Young's modulus.
Therefore, for example, Patent Document 1 provides a Cu—Be alloy containing Be as a copper alloy having excellent spring properties, strength, and electrical conductivity. This Cu—Be alloy is a precipitation hardening type high strength alloy in which strength is improved without decreasing the conductivity by aging precipitation of CuBe in the matrix phase.

  However, since this Cu-Be alloy contains Be which is an expensive element, the raw material cost is very high. Moreover, when manufacturing a Cu-Be alloy, a toxic Be oxide is generated. Therefore, in the manufacturing process, it is necessary to make the manufacturing equipment specially configured and strictly control so that Be oxide is not accidentally released to the outside. As described above, the Cu—Be alloy has a problem that both the raw material cost and the manufacturing cost are high and very expensive. Further, as described above, since it contains Be, which is a harmful element, it has been avoided from the viewpoint of environmental measures.

As a material that can replace the Cu—Be alloy, for example, Patent Document 2 provides a Cu—Ni—Si alloy (so-called Corson alloy). This Corson alloy is a precipitation hardening type alloy in which Ni ₂ Si precipitates are dispersed, and has relatively high electrical conductivity, strength, and stress relaxation characteristics. For this reason, it is widely used as a terminal for automobiles and signal system small terminals, and has been actively developed in recent years.

As other alloys, a Cu—Mg alloy described in Non-Patent Document 2, a Cu—Mg—Zn—B alloy described in Patent Document 3, and the like have been developed.
In these Cu-Mg alloys, as can be seen from the Cu-Mg phase diagram shown in FIG. 1, when the Mg content is 3.3 atomic% or more, solution treatment (500 ° C. to 900 ° C.), By performing the precipitation treatment, an intermetallic compound composed of Cu and Mg can be precipitated. That is, these Cu—Mg alloys can also have relatively high electrical conductivity and strength by precipitation hardening, similar to the above-described Corson alloy.

Japanese Patent Laid-Open No. 04-268033 Japanese Patent Laid-Open No. 11-036055 Japanese Patent Laid-Open No. 07-018354

Yukiya Nomura, “Technical Trends of High Performance Copper Alloy Strips for Connectors and Our Development Strategy”, Kobe Steel Technical Report Vol. 54No. 1 (2004) p. 2-8 M. Motokori and two others, “Grain boundary type precipitation in Cu—Mg alloys”, Vol. 19 (1980) p. 115-124

  However, the Corson alloy disclosed in Patent Document 2 has a relatively high Young's modulus of 125-135 GPa. Here, in a connector with a structure in which a male tab pushes up a female spring contact portion and the Young's modulus of the material constituting the connector is high, the contact pressure fluctuation at the time of insertion is severe, and the elastic limit is easily set. This is not preferable because it may cause plastic deformation.

In addition, in the Cu-Mg based alloy described in Non-Patent Document 2 and Patent Document 3, since the intermetallic compound is precipitated in the same manner as the Corson alloy, the Young's modulus tends to be high. It was not preferable as a connector.
In addition, since many coarse intermetallic compounds are dispersed in the matrix, these intermetallic compounds are the starting point during bending, and cracks are likely to occur. There was a problem that I couldn't.

  The present invention has been made in view of the above-described circumstances, has a low Young's modulus, high proof stress, high conductivity, and excellent bending workability, and is suitable for electronic and electrical parts such as terminals, connectors, and relays. It aims at providing the copper alloy for electronic devices, the manufacturing method of the copper alloy for electronic devices, and the copper alloy rolling material for electronic devices.

  In order to solve this problem, the present inventors have conducted intensive research. As a result, in a work-hardening type copper alloy of a Cu—Mg supersaturated solid solution prepared by quenching a Cu—Mg alloy after forming a solution, a low Young It has been found that it has a high rate, high yield strength, high conductivity, and excellent bending workability.

This invention is made | formed based on this knowledge, Comprising: The copper alloy for electronic devices of this invention contains Mg in the range of 3.3 atomic% or more and 6.9 atomic% or less, and remainder is Cu and When it is a binary alloy of Cu and Mg consisting only of inevitable impurities, and the conductivity σ (% IACS) is Mg content A atomic%,
σ ≦ 1.7241 / (− 0.0347 × A ² + 0.6569 × A + 1.7) × 100
And is characterized by being hot, cold or warm .

The copper alloy for electronic equipment according to the present invention includes a binary alloy of Cu and Mg containing Mg in a range of 3.3 atomic% to 6.9 atomic%, with the balance being only Cu and inevitable impurities. In the observation with a scanning electron microscope, the average number of intermetallic compounds having a particle size of 0.1 μm or more is 1 piece / μm ² or less, and hot, cold or warm processing has been performed. It is a feature.

Furthermore, the copper alloy for electronic devices according to the present invention includes a binary alloy of Cu and Mg containing Mg in a range of 3.3 atomic% or more and 6.9 atomic% or less, with the balance being only Cu and inevitable impurities. When the conductivity σ (% IACS) is Mg content A atomic%,
σ ≦ 1.7241 / (− 0.0347 × A ² + 0.6569 × A + 1.7) × 100
In the scanning electron microscope observation, the average number of intermetallic compounds having a particle size of 0.1 μm or more is 1 piece / μm ² or less, and it is hot, cold or warm working. It is characterized in that is applied.

In the copper alloy for electronic devices configured as described above, in the binary alloy of Cu and Mg, Mg is contained in the range of 3.3 atomic% to 6.9 atomic% above the solid solution limit. In addition, since the conductivity σ is set within the range of the above formula when the Mg content is A atomic%, the Mg—supersaturated Cu—Mg supersaturated in the parent phase It will be a solid solution.
Alternatively, in the binary alloy of Cu and Mg, Mg is contained in the range of 3.3 atomic% or more and 6.9 atomic% or less above the solid solution limit, and in observation with a scanning electron microscope, Since the average number of intermetallic compounds having a diameter of 0.1 μm or more is 1 piece / μm ² or less, precipitation of intermetallic compounds is suppressed, and Mg is supersaturated in the parent phase. -Mg supersaturated solid solution.

  In a copper alloy composed of such a Cu-Mg supersaturated solid solution, the Young's modulus tends to be low. For example, even if the male tab is applied to a connector inserted by pushing up a female spring contact portion, the contact pressure at the time of insertion Since the fluctuation is suppressed and the elastic limit is wide, there is no risk of plastic deformation easily. Therefore, it is particularly suitable for electronic and electrical parts such as terminals, connectors and relays.

In addition, since Mg is supersaturated in solid solution, a large amount of coarse intermetallic compound that is the starting point of cracking is not dispersed in the matrix phase, and bending workability is improved. Therefore, it is possible to mold electronic and electrical parts such as terminals, connectors, and relays having complicated shapes.
Further, since Mg is supersaturated, the strength can be improved by work hardening.
Moreover, since it is set as the binary system alloy of Cu and Mg which consists of Cu, Mg, and an unavoidable impurity, the fall of the electrical conductivity by another element is suppressed and electrical conductivity becomes comparatively high.

The average number particle size 0.1μm or more intermetallic compounds, using a field emission scanning electron microscope, magnification: 50,000 times field of view: calculated performs about 4.8 .mu.m ² in 10 fields of observation .
The particle size of the intermetallic compound is such that the major axis of the intermetallic compound (the length of the straight line that can be drawn the longest in the grain without contacting the grain boundary in the middle) and the minor axis (the direction intersecting the major axis at right angles) The average value of the length of the straight line that can be drawn the longest under conditions that do not contact the grain boundary.

Here, in the copper alloy for electronic devices described above, it is preferable that the Young's modulus E is 125 GPa or less and the 0.2% proof stress σ _0.2 is 400 MPa or more.
If the Young's modulus E is 125 GPa or less and the 0.2% proof stress σ _0.2 is 400 MPa or more, the elastic energy coefficient (σ _0.2 ² / 2E) increases, and plastic deformation does not easily occur. It is particularly suitable for electronic and electrical parts such as terminals, connectors and relays.

  The manufacturing method of the copper alloy for electronic devices of this invention is a manufacturing method of the copper alloy for electronic devices which produces the above-mentioned copper alloy for electronic devices, Comprising: Mg is 3.3 atomic% or more and 6.9 atomic% A heating step for heating a copper material including a Cu and Mg binary alloy including Cu and inevitable impurities only to a temperature of 500 ° C. to 900 ° C. It is characterized by comprising a rapid cooling step for cooling a copper material to 200 ° C. or less at a cooling rate of 200 ° C./min or more and a processing step for processing the rapidly cooled copper material.

According to the method for manufacturing a copper alloy for electronic equipment having this configuration, a heating process of heating a copper material, which is a binary alloy of Cu and Mg having the above-described composition, to a temperature of 500 ° C. to 900 ° C. Can be solutionized. Here, when the heating temperature is less than 500 ° C., solutionization is incomplete, and a large amount of intermetallic compounds may remain in the matrix. On the other hand, when the heating temperature exceeds 900 ° C., a part of the copper material becomes a liquid phase, and the structure and the surface state may become non-uniform. Therefore, the heating temperature is set in the range of 500 ° C. or higher and 900 ° C. or lower.
Moreover, since it has the rapid cooling process which cools the said heated copper raw material to 200 degrees C or less with the cooling rate of 200 degrees C / min or more, it can suppress that an intermetallic compound precipitates in the process of cooling. It becomes possible, and a copper raw material can be made into a Cu-Mg supersaturated solid solution.

Furthermore, since the processing process which processes with respect to the rapidly cooled copper raw material (Cu-Mg supersaturated solid solution) is provided, the intensity | strength improvement by work hardening can be aimed at. Here, the processing method is not particularly limited. For example, rolling is used when the final form is a plate or strip, drawing or extrusion is used when it is a wire or bar, and forging or pressing is used when it is a bulk shape. The processing temperature is not particularly limited, but is preferably in the range of −200 ° C. to 200 ° C. which is cold or warm so that precipitation does not occur. The processing rate is appropriately selected so as to be close to the final shape. However, when work hardening is considered, it is preferably 20% or more, and more preferably 30% or more.
Note that so-called low-temperature annealing may be performed after the processing step. This low-temperature annealing can further improve the mechanical properties.

The rolled copper alloy material for electronic equipment of the present invention is made of the above-described copper alloy for electronic equipment and is used as a copper material constituting terminals, connectors, and relays .
According to the copper alloy rolled material for electronic equipment having this configuration, the elastic energy coefficient (σ _0.2 ² / 2E) is high and plastic deformation does not easily occur.

  According to the present invention, a copper alloy for electronic equipment, a copper alloy for electronic equipment, which has a low Young's modulus, high yield strength, high electrical conductivity, and excellent bending workability, and is suitable for electronic electrical parts such as terminals, connectors and relays The manufacturing method of this and the copper alloy rolling material for electronic devices can be provided.

It is a Cu-Mg system phase diagram. It is a flowchart of the manufacturing method of the copper alloy for electronic devices which is this embodiment. 4 is a scanning electron microscope observation photograph in Example 3. FIG. 10 is a scanning electron microscope observation photograph in Comparative Example 5.

Below, the copper alloy for electronic devices which is one Embodiment of this invention is demonstrated.
The copper alloy for electronic devices according to the present embodiment includes Mg in a range of 3.3 atomic% to 6.9 atomic%, and the remainder is composed of Cu and Mg binary alloy composed of only Cu and inevitable impurities. Has been.
And, when the electrical conductivity σ (% IACS) is Mg content A atomic%,
σ ≦ 1.7241 / (− 0.0347 × A ² + 0.6569 × A + 1.7) × 100
It is within the range.
In the observation with a scanning electron microscope, the average number of intermetallic compounds having a particle diameter of 0.1 μm or more is 1 / μm ² or less.
The copper alloy for electronic equipment has a Young's modulus E of 125 GPa or less and a 0.2% proof stress σ _0.2 of 400 MPa or more.

(composition)
Mg is an element that has the effect of improving the strength and raising the recrystallization temperature without greatly reducing the electrical conductivity. Further, by dissolving Mg in the matrix, the Young's modulus can be kept low and excellent bending workability can be obtained.
Here, if the content of Mg is less than 3.3 atomic%, the effect cannot be achieved. On the other hand, if the Mg content exceeds 6.9 atomic%, an intermetallic compound containing Cu and Mg as main components remains when heat treatment is performed for solution treatment. There is a risk of cracking.
For these reasons, the Mg content is set to 3.3 atomic% or more and 6.9 atomic% or less.

  Furthermore, if the content of Mg is small, the strength is not sufficiently improved and the Young's modulus cannot be sufficiently reduced. Moreover, since Mg is an active element, when it is added excessively, there is a possibility that Mg oxide generated by reacting with oxygen is involved during melt casting. Therefore, it is more preferable that the Mg content is in the range of 3.7 atomic% to 6.3 atomic%.

  Inevitable impurities include Sn, Fe, Co, Al, Ag, Mn, B, P, Ca, Sr, Ba, Sc, Y, rare earth elements, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Re, Ru, Os, Se, Te, Rh, Ir, Pd, Pt, Au, Cd, Ga, In, Li, Si, Ge, As, Sb, Ti, Tl, Pb, Bi, S, O, C, Ni, Be, N, H, Hg, etc. are mentioned. These inevitable impurities are desirably 0.3% by mass or less in total.

(Conductivity σ)
In the binary alloy of Cu and Mg, when the electrical conductivity σ is Mg content A atomic%,
σ ≦ 1.7241 / (− 0.0347 × A ² + 0.6569 × A + 1.7) × 100
If it is within the range, there will be almost no intermetallic compound mainly composed of Cu and Mg.
That is, when the electrical conductivity σ exceeds the above formula, a large amount of intermetallic compounds mainly composed of Cu and Mg are present and the size is relatively large, so that bending workability is greatly deteriorated. . In addition, since an intermetallic compound containing Cu and Mg as main components is generated and the amount of Mg solid solution is small, the Young's modulus is also increased. Therefore, the manufacturing conditions are adjusted so that the electrical conductivity σ is within the range of the above formula.
In order to ensure that the above-described effects are achieved, the conductivity σ (% IACS) is
σ ≦ 1.7241 / (− 0.0292 × A ² + 0.6797 × A + 1.7) × 100
It is preferable to be within the range. In this case, since the amount of the intermetallic compound mainly composed of Cu and Mg is smaller, the bending workability is further improved.

(Organization)
In the copper alloy for electronic devices according to this embodiment, as a result of observation with a scanning electron microscope, the average number of intermetallic compounds having a particle diameter of 0.1 μm or more is 1 / μm ² or less. That is, almost no intermetallic compound mainly composed of Cu and Mg is precipitated, and Mg is dissolved in the matrix.
Here, if the solution formation is incomplete or the intermetallic compound is precipitated after the solution formation, and there is a large amount of a large intermetallic compound, these intermetallic compounds will be the starting point of cracking and cracking during processing. Or bending workability is greatly deteriorated. Further, if the amount of the intermetallic compound containing Cu and Mg as main components is large, the Young's modulus increases, which is not preferable.

As a result of investigating the structure, when the intermetallic compound having a particle size of 0.1 μm or more is 1 / μm ² or less in the alloy, that is, the intermetallic compound mainly composed of Cu and Mg does not exist or is in a small amount Good bending workability and a low Young's modulus can be obtained.
Furthermore, in order to ensure that the above-described effects are achieved, it is more preferable that the number of intermetallic compounds having a particle size of 0.05 μm or more is 1 / μm ² or less in the alloy.

The average number of intermetallic compounds is calculated by observing 10 visual fields using a field emission scanning electron microscope at a magnification of 50,000 times and a visual field of about 4.8 μm ² and calculating the average value.
The particle size of the intermetallic compound is such that the major axis of the intermetallic compound (the length of the straight line that can be drawn the longest in the grain without contacting the grain boundary in the middle) and the minor axis (the direction intersecting the major axis at right angles) The average value of the length of the straight line that can be drawn the longest under conditions that do not contact the grain boundary.

Next, the manufacturing method of the copper alloy for electronic devices which is this embodiment configured as above will be described with reference to the flowchart shown in FIG.
(Melting / Casting Process S01)
First, the above-described elements are added to a molten copper obtained by melting a copper raw material to adjust the components, thereby producing a molten copper alloy. In addition, Mg simple substance, Cu-Mg master alloy, etc. can be used for addition of Mg. Moreover, you may melt | dissolve the raw material containing Mg with a copper raw material. Moreover, you may use the recycling material and scrap material of this alloy.
Here, the molten copper is preferably so-called 4NCu having a purity of 99.99% by mass or more. In the melting step, it is preferable to use a vacuum furnace or an atmosphere furnace in an inert gas atmosphere or a reducing atmosphere in order to suppress oxidation of Mg.
Then, the copper alloy molten metal whose components are adjusted is poured into a mold to produce an ingot. When mass production is considered, it is preferable to use a continuous casting method or a semi-continuous casting method.

(Heating step S02)
Next, heat treatment is performed for homogenization and solution of the obtained ingot. Inside the ingot, there are intermetallic compounds and the like generated by the concentration of Mg due to segregation during the solidification process. Therefore, in order to eliminate or reduce these segregation and intermetallic compounds, etc., by performing a heat treatment to heat the ingot to 500 ° C. or more and 900 ° C. or less, Mg can be uniformly diffused in the ingot. Mg is dissolved in the matrix. In addition, it is preferable to implement this heating process S02 in a non-oxidizing or reducing atmosphere.

(Rapid cooling step S03)
Then, the ingot heated to 500 ° C. or higher and 900 ° C. or lower in the heating step S02 is cooled to a temperature of 200 ° C. or lower at a cooling rate of 200 ° C./min or higher. This rapid cooling step S03 suppresses the precipitation of Mg dissolved in the matrix as an intermetallic compound, and the average number of intermetallic compounds having a particle diameter of 0.1 μm or more in a scanning electron microscope observation. Is 1 piece / μm ² or less.

  In addition, in order to increase the efficiency of roughing and make the structure uniform, it is possible to perform a hot working after the heating step S02 and perform the rapid cooling step S03 after the hot working. In this case, there is no particular limitation on the processing method, for example, rolling when the final form is a plate or strip, drawing, extruding, groove rolling, etc. for a wire or bar, forging or pressing for a bulk shape. Can be adopted.

(Processing step S04)
The ingot that has undergone the heating step S02 and the rapid cooling step S03 is cut as necessary, and surface grinding is performed as necessary to remove the oxide film and the like generated in the heating step S02, the rapid cooling step S03, and the like. Then, processing is performed into a predetermined shape.
Here, there is no particular limitation on the processing method. For example, rolling is used when the final form is a plate or strip, drawing, extrusion or groove rolling is used when it is a wire or bar, and forging or pressing is used when it is a bulk shape. can do.

In addition, the temperature condition in this processing step S04 is not particularly limited, but is preferably in a range of −200 ° C. to 200 ° C. which is cold or warm processing. The processing rate is appropriately selected so as to approximate the final shape, but is preferably 20% or more in order to improve the strength by work hardening. Also. In order to further improve the strength, the processing rate is more preferably 30% or more.
Furthermore, as shown in FIG. 2, the above-described heating step S02, quenching step S03, and processing step S04 may be repeated. Here, the second and subsequent heating steps S02 are intended for thorough solutionization, recrystallization texture formation, or softening for improving workability. Moreover, it is not an ingot but a processed material.

(Heat treatment step S05)
Next, heat treatment is performed on the workpiece obtained in the machining step S04 in order to perform low-temperature annealing hardening or to remove residual strain. About this heat processing condition, it will set suitably according to the characteristic calculated | required by the product manufactured.
In the heat treatment step S05, it is necessary to set the heat treatment conditions (temperature, time, cooling rate) so that the solutionized Mg does not precipitate. For example, it is preferable that the temperature is about 1 minute to 1 hour at 200 ° C. and about 1 second to 1 minute at 300 ° C. The cooling rate is preferably 200 ° C./min or more.

The heat treatment method is not particularly limited, but preferably heat treatment at 100 to 500 ° C. for 0.1 second to 24 hours is performed in a non-oxidizing or reducing atmosphere. In addition, the cooling method is not particularly limited, but a method such as water quenching that allows the cooling rate to be 200 ° C./min or more is preferable.
Further, the above-described processing step S04 and heat treatment step S05 may be repeatedly performed.

Thus, the copper alloy for electronic devices which is this embodiment is produced. And as for the copper alloy for electronic devices which is this embodiment, the Young's modulus E shall be 125 GPa or less, and 0.2% yield strength (sigma) _0.2 shall be 400 Mpa or more.
Further, the conductivity σ (% IACS) is determined when the Mg content is A atomic%.
σ ≦ 1.7241 / (− 0.0347 × A ² + 0.6569 × A + 1.7) × 100
It will be set within the range.

According to the copper alloy for electronic devices according to the present embodiment configured as described above, in the binary alloy of Cu and Mg, Mg is 3.3 atomic% or more and 6.9 atoms or more which is not less than the solid solution limit. % And the conductivity σ (% IACS) is, when the Mg content is A atomic%,
σ ≦ 1.7241 / (− 0.0347 × A ² + 0.6569 × A + 1.7) × 100
It is set within the range. Further, in the observation with a scanning electron microscope, the average number of intermetallic compounds having a particle diameter of 0.1 μm or more is 1 piece / μm ² or less.

That is, the copper alloy for electronic devices according to this embodiment is a Cu—Mg supersaturated solid solution in which Mg is supersaturated in the matrix.
In a copper alloy composed of such a Cu-Mg supersaturated solid solution, the Young's modulus tends to be low. For example, even if the male tab is applied to a connector inserted by pushing up a female spring contact portion, the contact pressure at the time of insertion Since the fluctuation is suppressed and the elastic limit is wide, there is no risk of plastic deformation easily. Therefore, it is particularly suitable for electronic and electrical parts such as terminals, connectors and relays.

In addition, since Mg is supersaturated in solid solution, a large amount of coarse intermetallic compound that is the starting point of cracking is not dispersed in the matrix phase, and bending workability is improved. Therefore, it is possible to mold electronic and electrical parts such as terminals, connectors, and relays having complicated shapes.
Furthermore, since Mg is super-saturated, the strength is improved by work hardening, and a relatively high strength can be obtained.
Moreover, since it is set as the binary system alloy of Cu and Mg which consists of Cu, Mg, and an unavoidable impurity, the fall of the electrical conductivity by another element is suppressed and electrical conductivity can be made comparatively high.

And in the copper alloy for electronic devices, since Young's modulus E is 125 GPa or less and 0.2% yield strength σ _0.2 is 400 MPa or more, the elastic energy coefficient (σ _0.2 ² / 2E) is Since it becomes high and does not easily undergo plastic deformation, it is particularly suitable for electronic and electrical parts such as terminals, connectors, and relays.

Moreover, according to the manufacturing method of the copper alloy for electronic devices which is this embodiment, the ingot or processed material made into the binary system alloy of Cu and Mg of the above-mentioned composition is made into the temperature of 500 to 900 degreeC. The Mg solution can be formed by the heating step S02 for heating.
In addition, since the ingot or work material heated to 500 ° C. or more and 900 ° C. or less by the heating step S02 is provided with a quenching step S03 for cooling to 200 ° C. or less at a cooling rate of 200 ° C./min or more, cooling It is possible to suppress the precipitation of intermetallic compounds during the process, and the ingot or processed material after quenching can be made into a Cu-Mg supersaturated solid solution.

Furthermore, since the processing step S04 for processing the quenching material (Cu-Mg supersaturated solid solution) is provided, the strength can be improved by work hardening.
In addition, since the heat treatment step S05 is performed after the processing step S04 in order to perform low-temperature annealing hardening or to remove residual strain, it is possible to further improve the mechanical characteristics.

  As described above, according to the copper alloy for electronic devices according to the present embodiment, it has a low Young's modulus, high proof stress, high conductivity, and excellent bending workability, and is suitable for electronic and electrical parts such as terminals, connectors and relays. A suitable copper alloy for electronic equipment can be provided.

As mentioned above, although the copper alloy for electronic devices which is embodiment of this invention was demonstrated, 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, in the above-described embodiment, an example of a method for manufacturing a copper alloy for electronic devices has been described. However, the manufacturing method is not limited to this embodiment, and an existing manufacturing method may be selected as appropriate. Good.

Below, the result of the confirmation experiment performed in order to confirm the effect of this invention is demonstrated.
A copper raw material made of oxygen-free copper (ASTM B152 C10100) having a purity of 99.99% by mass or more was prepared, charged in a high-purity graphite crucible, and melted at high frequency in an atmosphere furnace having an Ar gas atmosphere. . Various additive elements were added to the obtained molten copper to prepare the component compositions shown in Table 1, and poured into a carbon mold to produce an ingot. The size of the ingot was about 20 mm thick x about 20 mm wide x about 100 to 120 mm long.

The obtained ingot was subjected to a heating process in which heating was performed for 4 hours under the temperature conditions shown in Table 1 in an Ar gas atmosphere, followed by water quenching.
The ingot after the heat treatment was cut and surface grinding was performed to remove the oxide film. Thereafter, cold rolling was performed at a processing rate shown in Table 1 to produce a strip having a thickness of about 0.5 mm and a width of about 20 mm.
And the heat treatment was implemented with respect to the obtained strip material on the conditions described in Table 1, and the strip material for characteristic evaluation was created.

(Processability evaluation)
As an evaluation of workability, the presence or absence of ear cracks during the cold rolling described above was observed. The case where no or almost no ear cracks were visually observed was ◎, the case where a small ear crack of less than 1 mm in length occurred was ○, the case where an ear crack of 1 mm or more and less than 3 mm occurred was Δ, and the length was 3 mm The case where the above-mentioned big ear crack generate | occur | produced was made into x, and what was fractured | ruptured in the middle of rolling due to the ear crack was made into xx.
In addition, the length of an ear crack is the length of the ear crack which goes to the width direction center part from the width direction edge part of a rolling material.

In addition, using the above-described strip for property evaluation, the mechanical properties and conductivity were measured,
(Mechanical properties)
A No. 13B test piece defined in JIS Z 2201 was taken from the strip for characteristic evaluation, and 0.2% proof stress σ _0.2 was measured by an offset method of JIS Z 2241.
The Young's modulus E was determined from the gradient of the load-elongation curve by attaching a strain gauge to the above-mentioned test piece.
In addition, the test piece was extract | collected so that the tension direction of a tension test might become parallel with 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.

(Bending workability)
Bending was performed according to three test methods of JBMA (Japan Copper and Brass Association Technical Standard) T307. A plurality of test pieces having a width of 10 mm and a length of 30 mm are taken from the strip for characteristic evaluation so that the rolling direction and the longitudinal direction of the test piece are parallel to each other, a W-type having a bending angle of 90 degrees and a bending radius of 0.5 mm. The W-bending test was performed using the jig.
Then, visually check the outer periphery of the bent portion, x if it breaks, △ if only a portion breaks, ◯ if it does not break and only a minute crack occurs, rupture or a minute crack Judgment was made as ◎ when the case cannot be confirmed.

(Tissue observation)
Mirror polishing and ion etching were performed on the rolled surface of each sample. In order to confirm the precipitation state of the intermetallic compound, observation was performed using a FE-SEM (Field Emission Scanning Electron Microscope) with a 10,000 × field of view (approximately 120 μm ² / field of view).
Next, in order to investigate the density of the intermetallic compound (pieces / μm ² ), a 10,000 times field of view (about 120 μm ² / field of view) in which the precipitation state of the intermetallic compound is not unique is selected. Ten continuous visual fields (approximately 4.8 μm ² / visual field) were taken at 10,000 times magnification. As for the particle size of the intermetallic compound, the major axis of the intermetallic compound (the length of the straight line that can be drawn the longest in the grain without contact with the grain boundary in the middle) and the minor axis (in the direction perpendicular to the major axis, the grain in the middle The average value of the length of the straight line that can be drawn the longest under conditions that do not contact the boundary). And the density (pieces / micrometer < ² >) of the intermetallic compound with a particle size of 0.1 micrometer and 0.05 micrometer was calculated | required.

  Tables 1 and 2 show the conditions and evaluation results. Moreover, as an example of the above-described structure observation, SEM observation photographs of Example 3 and Comparative Example 5 are shown in FIGS. 3 and 4, respectively.

In Comparative Example 1 in which the Mg content was lower than the range of the present invention, the Young's modulus remained relatively high at 127 GPa.
Moreover, in Comparative Examples 2 and 3 in which the Mg content is higher than the range of the present invention, large ear cracks occurred during cold rolling, and it was impossible to perform subsequent characteristic evaluation.

  Further, in Comparative Example 4 in which a copper alloy containing Ni, Si, Zn, and Sn, that is, a so-called Corson alloy, the temperature of the heating step for solution treatment was set to 980 ° C., and the heat treatment conditions were set to 400 ° C. × 4 h. Precipitation treatment of intermetallic compounds is performed. In Comparative Example 4, the occurrence of ear cracks is suppressed, and bending workability is ensured because the precipitates are fine. However, it is confirmed that the Young's modulus is as high as 131 GPa.

  Further, although the Mg content is within the range of the present invention, it is confirmed that in Comparative Example 5 in which the conductivity and the number of intermetallic compounds are out of the range of the present invention, the bending workability is inferior. The bending deterioration is presumed to be because a coarse intermetallic compound becomes the starting point of cracking.

On the other hand, in Inventive Example 1-10, the Young's modulus is set as low as 115 GPa or less, and the elasticity is excellent. In addition, when Invention Examples 3 and 8-10 having the same composition but different processing rates are compared, it is confirmed that 0.2% proof stress can be improved by increasing the processing rate.
From the above, according to the present invention example, a copper alloy for electronic equipment having a low Young's modulus, high yield strength, high electrical conductivity, and excellent bending workability, and suitable for electronic and electrical parts such as terminals, connectors and relays. It was confirmed that we can provide.

S02 Heating step S03 Rapid cooling step S04 Processing step

Claims (6)

Mg is included in a range of 3.3 atomic% to 6.9 atomic%, and the balance is a binary alloy of Cu and Mg consisting of only Cu and inevitable impurities,
When the electrical conductivity σ (% IACS) is Mg content A atomic%,
σ ≦ 1.7241 / (− 0.0347 × A ² + 0.6569 × A + 1.7) × 100
A copper alloy for electronic equipment, characterized in that it is within the range and is hot, cold or warm worked . Mg is included in a range of 3.3 atomic% to 6.9 atomic%, and the balance is a binary alloy of Cu and Mg consisting of only Cu and inevitable impurities,
In scanning electron microscope observation, the average number of intermetallic compounds having a particle size of 0.1 μm or more is 1 piece / μm ² or less, and hot, cold or warm processing is performed. Copper alloy for electronic equipment. Mg is included in a range of 3.3 atomic% to 6.9 atomic%, and the balance is a binary alloy of Cu and Mg consisting of only Cu and inevitable impurities,
When the electrical conductivity σ (% IACS) is Mg content A atomic%,
σ ≦ 1.7241 / (− 0.0347 × A ² + 0.6569 × A + 1.7) × 100
Is within the scope of
In scanning electron microscope observation, the average number of intermetallic compounds having a particle size of 0.1 μm or more is 1 piece / μm ² or less, and hot, cold or warm processing is performed. Copper alloy for electronic equipment. In the copper alloy for electronic devices as described in any one of Claims 1-3,
A copper alloy for electronic equipment, wherein Young's modulus E is 125 GPa or less and 0.2% proof stress σ0.2 is 400 MPa or more. It is a manufacturing method of the copper alloy for electronic devices which produces the copper alloy for electronic devices as described in any one of Claims 1-4,
A copper material containing Mg in a range of 3.3 atomic% to 6.9 atomic% with the balance being Cu and Mg consisting only of Cu and unavoidable impurities is 500 ° C. or higher and 900 ° C. or lower. A heating step of heating to a temperature of
A rapid cooling step of cooling the heated copper material to 200 ° C. or less at a cooling rate of 200 ° C./min or more;
A processing step for processing a rapidly cooled copper material;
The manufacturing method of the copper alloy for electronic devices characterized by the above-mentioned. It consists of the copper alloy for electronic devices as described in any one of Claims 1-4,
A copper alloy rolled material for electronic equipment, characterized by being used as a copper material constituting terminals, connectors, and relays.