JP5703975B2 - 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, as a copper alloy having excellent spring properties, strength, and electrical conductivity, for example, Patent Document 1 provides a Cu—Ni—Si based 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 resistance. 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 2, 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. 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 1 has a relatively high Young's modulus of 126 to 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.

Further, in the Cu-Mg based alloy described in Non-Patent Document 2 and Patent Document 2, since an intermetallic compound composed of Cu and Mg is precipitated, the Young's modulus tends to be high, and as described above, It was not preferable as a connector.
In addition, since a large amount of coarse intermetallic compounds of Cu and Mg are dispersed in the matrix phase, these intermetallic compounds are likely to be the starting point during bending, so that complex shapes are likely to occur. There is a problem that the connector cannot be molded.

  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 conducted extensive research, and as a result, added at least one or more of Cr and Zr to a Cu-Mg alloy, followed by solution treatment, processing, heat treatment, and low-temperature annealing. In a work-hardening type copper alloy in which second-phase particles containing one or more of Cr and Zr are dispersed in a Cu-Mg supersaturated solid solution, low Young's modulus, high proof stress, high conductivity, and excellent bending workability The knowledge that it has was obtained.

The present invention has been made based on such knowledge, and the copper alloy for electronic equipment of the present invention contains Mg in a range of 3.3 atomic% to less than 6.9 atomic%, and at least Cr and One or more kinds of Zr are included in the range of 0.001 atomic% or more and 0.15 atomic% or less, respectively, and the balance is Cu and inevitable impurities,
When the conductivity σ (% IACS) is Mg concentration A atom%,
σ ≦ 1.7241 / (− 0.0347 × A ² + 0.6569 × A + 1.7) × 100
It is characterized by being within the range of.

In the copper alloy for electronic devices having the above-described configuration, Mg is contained in the range of 3.3 atomic% or more and less than 6.9 atomic% above the solid solution limit, and the conductivity σ is Mg. When the content of is set to A atomic%, it is set within the range of the above formula, so that it is a Cu—Mg supersaturated solid solution in which Mg is supersaturated in the parent phase.
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.
Further, since Mg is supersaturated, the strength can be improved by work hardening.
In addition, a large amount of coarse intermetallic compounds mainly composed of Cu and Mg, which are the starting points of cracks, are not dispersed in the matrix phase, which improves the bending workability. Therefore, it is possible to mold electronic and electrical parts such as terminals, connectors, and relays having complicated shapes.

Furthermore, the copper alloy for electronic equipment of the present invention contains at least one or more of Cr and Zr in a range of 0.001 atomic% or more and 0.15 atomic% or less, respectively. Further, it is possible to improve workability and strength.
Further, Cr and Zr are precipitated in the matrix as dispersed particles containing them, so that the strength can be improved without lowering the electrical conductivity. In addition, if it is in the said range, since the dispersed particle containing Cr and Zr is very fine or a small amount, there is no possibility of adversely affecting the bending workability.

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.
Furthermore, in the above-described copper alloy for electronic devices, the average crystal grain size is preferably 20 μm or less. By setting the average crystal grain size to 20 μm or less, the 0.2% yield strength σ _0.2 can be further increased.

  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 less than 6.9 atomic% A copper material containing at least one of Cr and Zr in a range of 0.001 atomic% to 0.15 atomic%, with the balance being Cu and inevitable impurities, 300 ° C. A heating process for heating to a temperature of 900 ° C. or less, a quenching process for cooling the heated copper material to 200 ° C. or less at a cooling rate of 200 ° C./min or more, and processing the quenched copper material And a processing step to be performed.

According to the method for producing a copper alloy for electronic equipment having this configuration, a copper material composed of a copper alloy containing Cu, Mg, and at least one of Cr and Zr having the above composition is heated to a temperature of 300 ° C. or higher and 900 ° C. or lower. The solution of Mg can be formed by the heating step of heating. Here, when the heating temperature is less than 300 ° C., solutionization is incomplete, and a large amount of intermetallic compounds mainly containing Cu and Mg may remain in the matrix phase. 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 300 ° C. or higher and 900 ° C. or lower. In addition, in order to achieve such an effect reliably, it is preferable to make the heating temperature in a heating process into the range of 500 degreeC or more and 800 degrees C or less.
In addition, since the heated copper material is provided with a rapid cooling process that cools the heated copper material to 200 ° C. or less at a cooling rate of 200 ° C./min or more, an intermetallic compound containing Cu and Mg as main components in the course of cooling is provided. It becomes possible to suppress precipitation, 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, and drawing or extrusion, groove rolling, or forging or pressing is adopted when the shape is a wire or bar. 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 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. Yes.
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.
Moreover, it is preferable that the above-mentioned copper alloy rolled material for electronic devices is used as a copper material constituting a terminal, a connector, and a relay.

  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. It is a scanning electron microscope observation photograph in Example 3 of the present invention. It is a scanning electron microscope observation photograph in Example 10 of the present invention.

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 contains Mg in a range of 3.3 atomic% to less than 6.9 atomic%, and at least one of Cr and Zr is 0.001 atomic% or more, respectively. It is contained in the range of 0.15 atomic% or less, and the balance consists of Cu and inevitable impurities.
And, when the conductivity σ (% IACS) is Mg concentration A atom%,
σ ≦ 1.7241 / (− 0.0347 × A ² + 0.6569 × A + 1.7) × 100
It is within the range.
The copper alloy for electronic devices 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, when the Mg content is 6.9 atomic% or more, 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 less than 6.9 atomic%.

  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%.

  Cr and Zr are elements having an effect of easily refining the crystal grain size after the intermediate heat treatment. This is presumably because the second phase particles containing Cr and Zr are dispersed in the parent phase, and the second phase particles have an effect of suppressing the growth of crystal grains of the parent phase during the heat treatment. The effect of crystal grain refinement becomes more remarkable by repeating intermediate processing → intermediate heat treatment. Further, the dispersion of such fine second-phase particles and the refinement of crystal grains have the effect of further improving the strength without greatly reducing the electrical conductivity.

Here, if the content of Cr and Zr is less than 0.001 atomic%, the effect cannot be achieved. On the other hand, if the content of Cr and Zr exceeds 0.15 atomic%, there is a risk that ear cracks may occur during rolling.
For these reasons, the Cr and Zr contents are set to 0.001 atomic% or more and 0.15 atomic% or less, respectively.

Furthermore, if the contents of Cr and Zr are small, there is a possibility that the effect of improving the strength and refining the crystal grains cannot be achieved with certainty. Moreover, when there is much content of Cr and Zr, it will have a bad influence on rolling property and bending workability.
Therefore, it is more preferable that the contents of Cr and Zr are in the range of 0.005 atomic% or more and 0.12 atomic% or less, respectively.

  Inevitable impurities include Zn, Sn, Fe, Co, Al, Ag, Mn, B, P, Ca, Sr, Ba, Sc, Y, rare earth elements, Hf, V, Nb, Ta, 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 copper alloy having the above composition, when the conductivity σ (% IACS) is Mg concentration of 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, the amount of solid solution of Mg is reduced, and the Young's modulus is also increased. Therefore, the Young's modulus can be suppressed low and the workability can be improved by adjusting the manufacturing conditions so that the electrical conductivity σ is within the range of the above formula.

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. For addition of Mg, Cr, Zr, Mg, Cr, Zr alone or a mother alloy can be used. Moreover, you may melt | dissolve the raw material containing Mg, Cr, Zr 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, more preferably an atmosphere furnace having an inert gas atmosphere or a reducing atmosphere, in order to suppress oxidation of Mg, Cr, and Zr.
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 mainly composed of Cu and Mg generated by the concentration of Mg by segregation during the solidification process. Therefore, in order to eliminate or reduce these segregation and intermetallic compounds, etc., heat treatment is performed to heat the ingot to 300 ° C. or more and 900 ° C. or less, so that 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 300 ° 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. By this rapid cooling step S03, Mg dissolved in the matrix phase is prevented from being precipitated as an intermetallic compound.

  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 hot working method, for example, rolling when the final form is a plate or strip, drawing, extruding or grooving when the wire or bar is used, forging or pressing when the bulk shape is used. , 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.

The temperature condition in the processing step S04 is not particularly limited, but it is preferable that the temperature is in a range of −200 ° C. to 200 ° C. that is cold or warm processing so that precipitation does not occur. 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 for the purpose of thorough solution, recrystallization structure, refinement of crystal grains, precipitation of second phase particles containing Cr and Zr, and softening for improving workability. It becomes that. Moreover, it is not an ingot but a processed material.

(Heat treatment step S05)
Next, heat treatment is performed on the processed material obtained in the processing step S04 in order to improve the low temperature annealing hardening and the stress relaxation resistance. 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 to set the temperature at 200 ° C. for about 1 minute to 1 hour, at 300 ° C. for about 1 second to 5 minutes, and at 350 ° C. for about 1 second to 3 minutes. 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, when the conductivity σ (% IACS) is set to Mg concentration of A atom%,
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 of the present embodiment configured as described above, Mg is included in a range of 3.3 atomic% or more and less than 6.9 atomic%, and at least one of Cr and Zr When the above is included in the range of 0.001 atomic% or more and 0.15 atomic% or less, the balance is Cu and inevitable impurities, and the conductivity σ (% IACS) is Mg concentration of A atomic%,
σ ≦ 1.7241 / (− 0.0347 × A ² + 0.6569 × A + 1.7) × 100
It is within the range. 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, there is not a large amount of coarse intermetallic compounds mainly composed of Cu and Mg that are the starting points of cracks during bending. As a result, bending workability is improved. Therefore, it becomes possible to mold terminals, connectors and the like 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 at least one or more of Cr and Zr are further contained in the copper alloy in which Mg is dissolved, crystal grains can be refined and workability can be improved.
Furthermore, when the second phase particles containing Cr and Zr are dispersed, the strength can be further improved without lowering the electrical conductivity.

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 terminals, connectors and the like.
Moreover, 0.2% yield strength (sigma) _0.2 can be made high by making an average crystal grain diameter into 20 micrometers or less.

In addition, according to the method for manufacturing a copper alloy for electronic devices according to the present embodiment, an ingot or processed material made of a copper alloy containing at least one of Cu and Mg and at least one of Cr and Zr having the above-described composition is 300 ° C. The solution treatment of Mg can be performed by the heating step S02 in which heating is performed to a temperature of 900 ° C. or lower.
In addition, since the ingot or work material heated to 300 ° C. or more and 900 ° C. or less in the heating step S02 is provided with a rapid cooling 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 an intermetallic compound mainly composed of Cu and Mg in 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, to remove residual strain, and to improve the stress relaxation resistance, further improvement in mechanical properties. Can be achieved.

  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 Tables 1 and 2, and poured into a carbon mold to produce an ingot. The size of the ingot was about 20 mm thick x about 30 mm wide x about 100 to 120 mm long.

The obtained ingot was subjected to a heating step (homogenization / solution) for 4 hours under the temperature conditions shown in Table 1 in an Ar gas atmosphere, and then water quenching was performed. .
The ingot after the heat treatment was cut and surface grinding was performed to remove the oxide film. Thereafter, intermediate rolling was performed at a rolling rate described in Table 1 at room temperature, and the obtained strip material was subjected to intermediate heat treatment under the conditions described in Table 1, and as shown in Table 1, Repeated once or multiple times. Further, finish rolling was performed at room temperature, and finally heat treatment was performed. Surface grinding was performed as needed during the process to remove the oxide film by heat treatment. The final shape was a strip with a thickness of about 0.5 mm and a width of about 30 mm.

(Processability evaluation)
As an evaluation of workability, the presence or absence of ear cracks was observed after final finish rolling. 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 a length of 3 mm The case where the above-mentioned big ear crack generate | occur | produced was made into x, and the thing which fractured in the middle of rolling due to the ear crack was made into x.
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 obtained from the slope of the stress-strain curve obtained by attaching a strain gauge to the above-mentioned test piece, measuring the load and elongation.
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 in accordance with four test methods of Japan Copper and Brass Association Technical Standard JCBA-T307: 2007. 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 perpendicular to each other, and 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 at 10,000 to 100,000 times using an FE-SEM (Field Emission Scanning Electron Microscope).
Further, Example 3 and Example 10 of the strips for property evaluation were observed at about 40,000 times, and the components of the precipitates were confirmed using EDX (energy dispersive X-ray spectroscopy). The observation results are shown in FIGS.

(Crystal grain size measurement)
Each sample was mirror-polished and etched, photographed with an optical microscope so that the rolling direction was beside the photograph, and observed with a 1000 × field of view (about 300 μm × 200 μm). Next, according to the cutting method of JIS H 0501, the crystal grain size is drawn in 5 vertical and horizontal line segments, counting the number of crystal grains to be completely cut, and the average value of the cutting length is calculated. The crystal grain size was used.

  The conditions and evaluation results are shown in Tables 1, 2, 3, and 4.

In Comparative Examples 1 and 4 in which the Mg content was lower than the range of the present invention, Young's modulus was as high as 126 GPa and 127 GPa.
Further, in Comparative Examples 2 and 5 in which the Mg content is higher than the range of the present invention, large ear cracks were generated during cold rolling, and fractured during the rolling. could not. Further, in Comparative Example 3 in which the Cr content is higher than the range of the present invention and in Comparative Example 6 in which the Zr content is higher than the range of the present invention, although not reaching breakage during cold rolling, Large ear cracks occurred during hot rolling, and it was impossible to perform subsequent characteristic evaluation.

Furthermore, the contents of Mg and the contents of Cr and Zr are within the scope of the present invention, but in Comparative Examples 7, 8, 9, and 10, where the electrical conductivity deviates from the scope of the present invention, the bending workability is inferior. Is confirmed. This is presumably because coarse intermetallic compounds mainly composed of Cu and Mg serve as starting points for cracking.
Moreover, in the conventional example made into the copper alloy containing Ni, Si, Zn, Sn, what is called a Corson alloy, the temperature of the heating process for solution treatment shall be 980 degreeC, and the heat processing conditions shall be 400 degreeC x 4h, and it is between metals. Compound precipitation treatment is performed. In this conventional example, the occurrence of ear cracks is suppressed, and the bending workability is ensured because the precipitates are fine. However, it is confirmed that the Young's modulus is as high as 131 GPa.

On the other hand, in Inventive Example 1-18, the Young's modulus is set as low as 119 GPa or less, and the elasticity is excellent. In addition, when Invention Example 3-5 and Invention Example 10-12 having the same composition and different processing rates are compared, 0.2% proof stress can be improved by repeating intermediate rolling and intermediate heat treatment. It is confirmed that In Example 7 of the present invention, the ear cracks are indicated by Δ, but this is of a practically acceptable level. In addition, the inventive examples 7, 13-15, and 18 have a bending workability of Δ, but it has been confirmed that this is also a practically no problem.
Moreover, as shown in FIG. 3, in the present invention example 3 containing Cr, although coarse precipitate particles are observed, coarse precipitates containing Mg are not observed. Moreover, as shown in FIG. 4, in the present invention example 10 containing Zr, although coarse particles of Zr and Cu are confirmed, coarse precipitates containing Mg are not observed.
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 the range of 3.3 atomic% to less than 6.9 atomic%, and at least one of Cr and Zr is included in the range of 0.001 atomic% to 0.15 atomic%, respectively, and the balance Cu and inevitable impurities,
When the conductivity σ (% IACS) is Mg concentration A atom%,
σ ≦ 1.7241 / (− 0.0347 × A ² + 0.6569 × A + 1.7) × 100
The copper alloy for electronic devices characterized by being in the range of. In the copper alloy for electronic devices according to claim 1,
A copper alloy for electronic equipment, wherein Young's modulus E is 125 GPa or less and 0.2% proof stress σ _0.2 is 400 MPa or more. In the copper alloy for electronic devices according to claim 1 or 2,
A copper alloy for electronic equipment, wherein the average crystal grain size is 20 μm or less. 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 1-3,
Mg is included in the range of 3.3 atomic% to less than 6.9 atomic%, and at least one of Cr and Zr is included in the range of 0.001 atomic% to 0.15 atomic%, respectively, and the balance Heating the copper material in which Cu and inevitable impurities are heated to a temperature of 300 ° C. or higher and 900 ° C. or lower,
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 1-3, Young's modulus E of a rolling direction is 125 GPa or less, 0.2% yield strength (sigma) _0.2 of a rolling direction is 400 Mpa or more, A rolled copper alloy material for electronic equipment. A copper alloy rolled material for electronic equipment according to claim 5,
A copper alloy rolled material for electronic equipment, characterized by being used as a copper material constituting terminals, connectors, and relays.