JP2013104096A - Copper alloy for electronic equipment, method for producing copper alloy for electronic equipment, copper alloy plastic working material for electronic equipment, and part for electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy for electronic equipment having high yield strength and excellent bendability and suitable for parts for electronic equipment such as a terminal, a connector, a relay, and a lead frame, and to provide a method for producing a copper alloy for electronic equipment, a copper alloy plastic working material for electronic equipment, and parts for electronic equipment.SOLUTION: The copper alloy for electronic equipment includes Mg in an amount of 3.3 atom% or more and 6.9 atom% or less, and further contains one or two or more of at least Pd and Ag each in an amount of 0.1 atom% or more and 5.0 atom% or less, with the balance being substantially Cu and inevitable impurities. In the scanning electron microscope observation of the alloy, the average number of intermetallic compounds essentially comprising Cu and Mg having a particle size of 0.1 μm or more is 1/μmor less.

Description

  The present invention relates to a copper alloy for electronic devices suitable for electronic device components such as terminals, connectors, relays, lead frames, etc., a method for producing a copper alloy for electronic devices, a copper alloy plastic working material for electronic devices, and an electronic device component It is about.

  2. Description of the Related Art Conventionally, along with downsizing of electronic devices and electrical devices, electronic device parts such as terminals, connectors, relays, and lead frames used in these electronic devices and electrical devices have been reduced in size and thickness. . For this reason, a copper alloy excellent in springiness, strength, and electrical conductivity is required as a material constituting electronic device parts. In particular, as described in Non-Patent Document 1, a copper alloy having high proof strength is desirable as a copper alloy used as a component for electronic equipment such as terminals, connectors, relays, and lead frames.

Here, as a copper alloy used as an electronic device component such as a terminal, a connector, a relay, or a lead frame, a Cu—Mg alloy described in Non-Patent Document 2 or a Cu alloy described in Patent Document 1 -Mg-Zn-B alloys and the like have been developed.
In these Cu-Mg based alloys, as can be seen from the Cu-Mg based phase diagram shown in Fig. 1, when the Mg content is 3.3 atomic% or more, by performing solution treatment and precipitation treatment, An intermetallic compound composed of Cu and Mg can be deposited. That is, these Cu—Mg alloys can have relatively high electrical conductivity and strength by precipitation hardening.

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, in the Cu—Mg-based alloys described in Non-Patent Document 2 and Patent Document 1, a large amount of coarse intermetallic compounds containing Cu and Mg are dispersed in the parent phase. Since these intermetallic compounds sometimes start from cracks and the like, there is a problem that electronic parts having complicated shapes cannot be formed.
In particular, electronic parts used in consumer products such as mobile phones and personal computers have been reduced in size and weight, and there is a need for copper alloys for electronic equipment that have both strength and bending workability. Yes. In addition, in electronic device parts used for automobiles and the like, there are cases where they are placed in a high-temperature environment such as an engine room, and therefore a copper alloy for electronic devices having excellent strength and conductivity is required.

  The present invention has been made in view of the above-described circumstances, and has high proof stress, excellent bending workability, and is suitable for electronic device parts such as terminals, connectors, relays, and lead frames. It is an object to provide an alloy, a method for producing a copper alloy for electronic equipment, a copper alloy plastic working material for electronic equipment, and an electronic equipment component.

  In order to solve this problem, the present inventors have conducted intensive research. As a result, in a work-saturated copper alloy of a supersaturated solid solution produced by quenching a Cu-Mg alloy after solution treatment, high yield strength and excellent The knowledge that it has bending workability was obtained. Moreover, the copper alloy which consists of this supersaturated solid solution acquired the knowledge that bending workability could be improved further by adding at least 1 sort (s) of Pd and Ag.

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 6.9 atomic%, and further includes at least Pd and Ag. 1 type or 2 types or more in a range of 0.1 atomic% or more and 5.0 atomic% or less, respectively, and the balance is substantially Cu and inevitable impurities. The average number of intermetallic compounds mainly composed of Cu and Mg of 1 μm or more is 1 piece / μm ² or less.

As shown in the phase diagram of FIG. 1, the copper alloy for electronic equipment having the above-described configuration contains Mg in the range of 3.3 atomic% to 6.9 atomic% above the solid solution limit. In addition, in the observation with a scanning electron microscope, the average number of intermetallic compounds mainly composed of Cu and Mg having a particle size of 0.1 μm or more is 1 / μm ² or less. Precipitation of the intermetallic compound as the main component is suppressed, and the Mg is a supersaturated solid solution in which the matrix phase is supersaturated in the mother phase.

The average number of intermetallic compounds mainly composed of Cu and Mg having a particle size of 0.1 μm or more was 10 × at a magnification of 50,000 times and a field of view of about 4.8 μm ² using a field emission scanning electron microscope. Calculate by observing the visual field.
In addition, the particle size of the intermetallic compound containing Cu and Mg as the main components is the major axis of the intermetallic compound (the length of the straight line that can be drawn the longest in the grain under the condition of not contacting the grain boundary in the middle) and the minor axis (major axis and It is defined as an average value of the length of a straight line that can be drawn longest in a direction that intersects at right angles and does not contact the grain boundary in the middle.

In a copper alloy composed of such a supersaturated solid solution, 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 bending workability. It will be. Therefore, it is possible to mold electronic parts such as terminals, connectors, relays, and lead frames having complicated shapes.
Further, since Mg is supersaturated, the strength can be improved by work hardening.

  The copper alloy for electronic equipment of the present invention contains at least one or more of Pd and Ag within a range of 0.1 atomic% to 5.0 atomic%, respectively. Can be greatly improved. That is, even if the strength is improved, the bending workability is not greatly deteriorated, and it is possible to mold a thin and complicated electronic device part. This is presumably because Pd and Ag are elements that can increase the strength without greatly reducing the stacking fault energy.

Here, in the above-described copper alloy for electronic devices, it is preferable that the 0.2% proof stress σ _0.2 is 400 MPa or more.
When the 0.2% proof stress σ _0.2 is 400 MPa or more, plastic deformation does not easily occur, so that it is particularly suitable for electronic device parts such as terminals, connectors, relays, and lead frames.

In the above-described copper alloy for electronic devices, the minimum bending radius ratio (MBR / t) is preferably 4 or less.
In this case, since the bending workability is good, it is possible to mold an electronic device component having a complicated shape.

  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% or less And further containing at least one or more of Pd and Ag in a range of 0.1 atomic% to 5.0 atomic%, respectively, with the balance being substantially Cu and inevitable impurities. A heating process for heating the copper material to 400 ° C. or more and 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 a quenched copper material And a processing step of plastic processing.

According to the method for producing a copper alloy for electronic equipment having this configuration, a copper material made of a copper alloy containing Cu, Mg, and at least one or more of Pd and Ag having the above composition is 400 ° C. or higher and 900 ° C. or lower. The solution of Mg can be performed by a heating step of heating to a temperature. Here, when the heating temperature is less than 400 ° 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 400 ° C to 900 ° C. 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 850 degrees C or less. Furthermore, it is more preferable that the heating temperature in the heating step be in the range of 520 ° C. or higher and 800 ° C. or lower.
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 supersaturated solid solution.

Furthermore, since the process which performs plastic processing with respect to the rapidly cooled copper raw material (supersaturated solid solution) is provided, the strength improvement by work hardening can be aimed at.
Here, the plastic working method is not particularly limited. For example, when the final form is a plate or strip, rolling, when wire or bar is drawn, extrusion, groove rolling, or forging or pressing is adopted when the shape is bulk. . 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.

  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% or less And further containing at least one or more of Pd and Ag in a range of 0.1 atomic% to 5.0 atomic%, respectively, with the balance being substantially Cu and inevitable impurities. And a finish heat treatment step for plastically processing the copper material into a predetermined shape, and a finish heat treatment step for performing heat treatment after the finish work step.

  According to the method for manufacturing a copper alloy for electronic equipment having this configuration, a finishing process for plastic processing the copper material having the above-described composition into a predetermined shape, and a finishing heat treatment process for performing a heat treatment after the finishing process, Thus, by this finishing heat treatment step, it is possible to improve the yield strength, the bending workability, and the stress relaxation resistance.

The copper alloy plastic working material for electronic equipment of the present invention is made of the above-mentioned copper alloy for electronic equipment, and is characterized in that 0.2% proof stress σ _0.2 is 400 MPa or more.
According to the copper alloy plastic working material for electronic equipment having this configuration, the 0.2% proof stress σ _0.2 is high and it is not easily plastically deformed, so that it is suitable as a material for constituting electronic equipment parts.
In this specification, the plastic working material refers to a copper alloy that has undergone plastic working in any manufacturing process.

Moreover, the copper alloy plastic working material for electronic devices of this invention consists of the above-mentioned copper alloy for electronic devices, and minimum bending radius ratio (MBR / t) is 4 or less, It is characterized by the above-mentioned.
According to the copper alloy plastic working material for electronic equipment having this configuration, the minimum bending radius ratio (MBR / t) is 4 or less and the bending workability is improved. Can be formed.

  Moreover, it is preferable that the above-mentioned copper alloy plastic working material for electronic devices is used as a copper material constituting components for electronic devices such as terminals, connectors, relays, and lead frames.

Furthermore, the electronic device component of the present invention is characterized by comprising the above-described copper alloy for electronic devices.
Electronic device parts with this configuration (for example, terminals, connectors, relays, and lead frames) have high yield strength and excellent bending workability, so there is no cracking even in complex shapes, and reliability is high. Will improve.

  According to the present invention, high yield strength, excellent bending workability, suitable for electronic equipment parts such as terminals, connectors, relays, lead frames, etc., a copper alloy for electronic equipment, a method for producing a copper alloy for electronic equipment, The copper alloy plastic working material for electronic devices and the components 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.

Embodiments of the present invention will be described below with reference to the drawings.
The component composition of the copper alloy for electronic devices according to this embodiment includes Mg in the range of 3.3 atomic% to 6.9 atomic%, and further includes at least one or more of Pd and Ag, each of 0 In the range of 1 atomic% to 5.0 atomic%, the balance is substantially Cu and inevitable impurities.

And the copper alloy for electronic devices which is this embodiment WHEREIN: In scanning electron microscope observation, the average number of the intermetallic compound which has a particle size of 0.1 micrometer or more and which has Cu and Mg as a main component is 1 piece / micrometer < ² > or less. It is said that.
That is, the intermetallic compound which has Cu and Mg as the main components is hardly precipitated, Mg is solid-solved in the matrix, and the copper alloy for electronic devices according to this embodiment is a supersaturated solid solution. It is.

Moreover, in the copper alloy for electronic devices which is this embodiment, 0.2% yield strength (sigma) _0.2 is 400 Mpa or more.
Furthermore, in the copper alloy for electronic devices which is this embodiment, the minimum bending radius ratio (MBR / t) is 4 or less.

(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, excellent bending workability can be obtained by dissolving Mg in the matrix.
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, when there is little content of Mg, intensity | strength will not fully improve. 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%.

Pd and Ag are elements having an effect of improving the bending workability of a copper alloy made into a supersaturated solid solution. Since Pd and Ag are elements that can increase the strength without greatly reducing the stacking fault energy, even if the strength is improved, the bending workability does not decrease.
Here, when the content of at least one of Pd and Ag is less than 0.1 atomic%, the effect cannot be achieved. On the other hand, if the content of at least one or more of Pd and Ag exceeds 5.0 atomic%, it is not preferable because the grounding cost increases remarkably.
For these reasons, the content of at least one of Pd and Ag is set within the range of 0.1 atomic% to 5.0 atomic%.

Inevitable impurities include Ni, Si, Mn, Li, Ti, Fe, Co, Zn, Sn, Al, 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, Pt, Au, Cd, Ga, In, Ge, As, Sb, Tl, Pb, Bi, S, O, C, Be, N, H, Hg, etc. are mentioned. These inevitable impurities are desirably 0.3% by mass or less in total.
In particular, Sn is preferably less than 0.1% by mass and Zn is preferably less than 0.01% by mass. This is because when Sn is added in an amount of 0.1% by mass or more, precipitation of an intermetallic compound mainly composed of Cu and Mg is likely to occur, and when Zn is added in an amount of 0.01% by mass or more, melt casting is performed. This is because fumes are generated in the process and adhere to the furnace and mold members to deteriorate the surface quality of the ingot and the stress corrosion cracking resistance.

(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 mainly composed of Cu and Mg having a particle diameter of 0.1 μm or more is 1 / μm ^2. It is as follows. That is, almost no intermetallic compound mainly composed of Cu and Mg is precipitated, and Mg is dissolved in the matrix.
Here, when the solution formation is incomplete, or when an intermetallic compound mainly composed of Cu and Mg is precipitated after solution formation, a large amount of intermetallic compounds exist in a large size. It becomes a starting point of cracking, cracking occurs during processing, and bending workability is greatly deteriorated.

As a result of investigating the structure, when the intermetallic compound containing Cu and Mg as main components having a particle size of 0.1 μm or more is 1 / μm ² or less in the alloy, that is, the intermetallic compound containing Cu and Mg as main components. When there is no or a small amount, good bending workability can be obtained.
Furthermore, in order to ensure that the above-described effects are achieved, the number of intermetallic compounds mainly composed of Cu and Mg having a particle diameter of 0.05 μm or more is 1 / μm ² or less in the alloy. More preferred.

The average number of intermetallic compounds mainly composed of Cu and Mg was observed using a field emission scanning electron microscope with 10 fields of view at a magnification of 50,000 times and a field of view of about 4.8 μm ^2. The average value is calculated.
In addition, the particle size of the intermetallic compound containing Cu and Mg as the main components is the major axis of the intermetallic compound (the length of the straight line that can be drawn the longest in the grain under the condition of not contacting the grain boundary in the middle) and the minor axis (major axis and It is defined as an average value of the length of a straight line that can be drawn longest in a direction that intersects at right angles and does not contact the grain boundary in the middle.

Here, the intermetallic compound containing Cu and Mg as main components has a crystal structure represented by the chemical formula MgCu ₂ , prototype MgCu ₂ , Pearson symbol cF24, and space group number Fd-3m.

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.
In the following manufacturing method, when rolling is used as the processing step, the processing rate corresponds to the rolling rate.

(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, the raw material containing Mg may be dissolved together with the 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. Further, in the melting step, it is preferable to use a vacuum furnace or an atmosphere furnace having 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. In consideration of mass production, 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 400 ° C. or more and 900 ° C. or less, so that Mg can be uniformly diffused in the ingot. Mg is dissolved in the matrix. The heating step S02 is preferably performed in a non-oxidizing or reducing atmosphere.
Here, when the heating temperature is less than 400 ° 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 400 ° C. or higher and 900 ° C. or lower. More preferably, it is 500 degreeC or more and 850 degrees C or less, More preferably, you may be 520 degreeC or more and 800 degrees C or less.

(Rapid cooling step S03)
And the copper raw material heated to 400 degreeC or more and 900 degrees C or less in heating process S02 is cooled by the cooling rate of 200 degrees C / min or more to the temperature of 200 degrees C or less. This rapid cooling step S03 suppresses the precipitation of Mg dissolved in the matrix as an intermetallic compound containing Cu and Mg as main components. In observation with a scanning electron microscope, Cu having a particle diameter of 0.1 μm or more is suppressed. The average number of intermetallic compounds containing Mg and Mg as main components can be 1 / μm ² or less. That is, the copper material can be made into a supersaturated solid solution.
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.

(Intermediate processing step S04)
The copper material 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, plastic working is performed into a predetermined shape.
In addition, the temperature condition in the intermediate processing step S04 is not particularly limited, but it is preferable to be within 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. However, in order to reduce the number of intermediate heat treatment steps S05 until the final shape is obtained, the processing rate is preferably set to 20% or more. Moreover, it is more preferable that the processing rate is 30% or more. The plastic working method is not particularly limited, but when the final shape is a plate or strip, it is preferable to employ rolling. It is preferable to employ extrusion or groove rolling in the case of a wire or bar, and forging or pressing in the case of a bulk shape. Further, S02 to S04 may be repeated for thorough solution.

(Intermediate heat treatment step S05)
After the intermediate processing step S04, heat treatment is performed for the purpose of thorough solution, recrystallization structure, or softening for improving workability.
The heat treatment method is not particularly limited, but the heat treatment is preferably performed in a non-oxidizing atmosphere or a reducing atmosphere under conditions of 400 ° C. to 900 ° C. More preferably, it is 500 degreeC or more and 850 degrees C or less, More preferably, you may be 520 degreeC or more and 800 degrees C or less.

Here, in the intermediate heat treatment step S05, the copper material heated to 400 ° C. or more and 900 ° C. or less is cooled to a temperature of 200 ° C. or less at a cooling rate of 200 ° C./min or more. Such rapid cooling suppresses the precipitation of Mg dissolved in the matrix as an intermetallic compound containing Cu and Mg as main components. The average number of intermetallic compounds mainly composed of Cu and Mg of 1 μm or more can be 1 / μm ² or less. That is, the copper material can be made into a supersaturated solid solution.

(Finishing process S06)
The copper material after the intermediate heat treatment step S05 is finished into a predetermined shape. The temperature condition in the finishing process S06 is not particularly limited, but it is preferably performed at room temperature. 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. The plastic working method is not particularly limited, but when the final shape is a plate or strip, it is preferable to employ rolling. It is preferable to employ extrusion or groove rolling in the case of a wire or bar, and forging or pressing in the case of a bulk shape.

(Finish heat treatment step S07)
Next, a finishing heat treatment is performed on the plastic workpiece obtained in the finishing step S06 in order to improve the stress relaxation resistance and perform low-temperature annealing hardening or to remove residual strain. .
The heat treatment temperature is preferably in the range of 200 ° C to 800 ° C. In the finish heat treatment step S07, it is necessary to set heat treatment conditions (temperature, time, cooling rate) so that solutionized Mg does not precipitate. For example, it is preferable to set at 250 ° C. for about 10 seconds to 24 hours, 300 ° C. for about 5 seconds to 4 hours, and 500 ° C. for about 0.1 seconds to 60 seconds. This heat treatment is preferably performed in a non-oxidizing atmosphere or a reducing atmosphere.

Moreover, it is preferable that a cooling method cools the said copper raw material heated, such as water quenching, to 200 degrees C or less with the cooling rate of 200 degrees C / min or more. Such rapid cooling suppresses the precipitation of Mg dissolved in the matrix as an intermetallic compound containing Cu and Mg as main components. The average number of intermetallic compounds mainly composed of Cu and Mg of 1 μm or more can be 1 / μm ² or less. That is, the copper material can be made into a supersaturated solid solution.
Furthermore, the above-described finishing processing step S06 and finishing heat treatment step S07 may be repeated. The intermediate heat treatment step and the finish heat treatment step can be distinguished by whether or not the purpose is to recrystallize the structure after plastic working in the intermediate processing step or the finishing step.

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, 0.2% yield strength (sigma) _0.2 shall be 400 Mpa or more. The minimum bending radius ratio (MBR / t) is 4 or less.

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% to 6.9 atomic%, and at least one of Pd and Ag or Two or more types are included in the range of 0.1 atomic% or more and 5.0 atomic% or less, respectively, and the balance is substantially Cu and inevitable impurities. In observation with a scanning electron microscope, Cu having a particle diameter of 0.1 μm or more The average number of intermetallic compounds mainly composed of Mg and Mg is 1 / μm ² or less.

That is, the copper alloy for electronic devices according to this embodiment is a supersaturated solid solution in which Mg is supersaturated in the matrix phase.
In a copper alloy composed of such a supersaturated solid solution, 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 parent phase, and bending workability is improved. become. Therefore, it is possible to mold electronic device parts such as terminals, connectors, relays, and lead frames 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 the copper alloy for electronic devices which is this embodiment contains at least 1 type or 2 types of Pd and Ag in the range of 0.1 atomic% or more and 5.0 atomic% or less, respectively, it is a bending process. The sex can be greatly improved. That is, even if the strength is improved, the bending workability is not greatly deteriorated, and it is possible to mold a thin and complicated electronic device part.

And in the copper alloy for electronic devices which is this embodiment, since 0.2% yield strength (sigma) _0.2 is 400 MPa or more, since it does not easily plastically deform, a terminal, a connector, a relay, a lead | read | reed It is particularly suitable for electronic parts of frames. More preferably, the 0.2% proof stress σ _0.2 is 500 MPa or more.
Moreover, in the copper alloy for electronic devices which is this embodiment, since the minimum bending radius ratio (MBR / t) is 4 or less, it becomes possible to shape | mold the electronic device component of a complicated shape.

According to the method for producing a copper alloy for electronic devices according to this embodiment, the ingot of the above-described composition or processed material is heated to 400 ° C. or higher and 900 ° C. or lower to heat Mg to form a solution. be able to.
In addition, since the ingot or work material heated to 400 ° C. or more and 900 ° C. or less in the heating step S02 is provided with a rapid cooling step S03 that cools 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 containing Cu and Mg as main components in the process, and the ingot or processed material after rapid cooling can be made into a supersaturated solid solution.

Furthermore, since the intermediate processing step S04 for processing the quenching material (supersaturated solid solution) is provided, a shape close to the final shape can be easily obtained.
In addition, since the intermediate heat treatment step S05 is provided after the intermediate processing step S04 for the purpose of thorough solution, recrystallization structure or softening for improving workability, the characteristics and workability are improved. be able to.
In addition, in the intermediate heat treatment step S05, the copper material heated to 400 ° C. or more and 900 ° C. or less is cooled to 200 ° C. or less at a cooling rate of 200 ° C./min or more. Precipitation of the intermetallic compound as a main component can be suppressed, and the copper material after quenching can be made into a supersaturated solid solution.

And in the manufacturing method of the copper alloy for electronic devices which is this embodiment, after the finishing process S06 for processing the strength improvement by work hardening and processing into a predetermined shape, improvement in stress relaxation resistance and low temperature annealing hardening are performed. Since the finishing heat treatment step S07 is performed to perform the heat treatment for removing the residual strain, the yield strength can be improved and the bending workability can be improved.
In the finish heat treatment step S07, heat treatment is performed in the range of 200 ° C. or higher and 800 ° C. or lower, and then the heated copper material is cooled to 200 ° C. or lower at a cooling rate of 200 ° C./min or higher. Therefore, it becomes possible to suppress precipitation of an intermetallic compound containing Cu and Mg as main components in the course of cooling, and the copper alloy for electronic equipment after the finish heat treatment step S07 can be made into a supersaturated solid solution.

As mentioned above, although the manufacturing method of the copper alloy for electronic devices which is embodiment of this invention, the copper alloy plastic processing material for electronic devices, the copper alloy for electronic devices was demonstrated, this invention is not limited to this, The Modifications can be made as appropriate without departing 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, intermediate rolling was performed at room temperature at a rolling rate described in Table 1. And the intermediate heat processing was implemented in the salt bath on the conditions of the temperature described in Table 1 with respect to the obtained strip. Thereafter, water quenching was performed.

Next, finish rolling was performed at the rolling rates shown in Table 1 to produce strips having a thickness of 0.25 mm and a width of about 20 mm.
And after finishing rolling, finishing heat processing was implemented in the salt bath on the conditions shown in the table | surface, and then water quenching was implemented and the strip for characteristic evaluation was created.

(Processability evaluation)
As an evaluation of workability, the presence or absence of ear cracks during the above-described intermediate rolling 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 a length of 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.

Using the above-mentioned strips 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 test piece was collected in a direction parallel to the rolling direction.

(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 parallel, and a W-shaped jig having a bending angle of 90 degrees and a bending radius R A W-bending test was conducted.
And the crack in that case is evaluated according to 5 evaluation methods of Japan Copper and Brass Association technical standard JCBA-T307: 2007, and R / is the ratio of the bending radius R and the sheet thickness t when the judgment is AC. The evaluation was performed by defining the minimum value of t as the minimum bending radius ratio (MBR / t).

(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 containing Cu and Mg as main components, the observation was performed using a FE-SEM (Field Emission Scanning Electron Microscope) with a 10,000 × field of view (about 120 μm ² / field of view). .
Next, in order to investigate the density of intermetallic compounds mainly composed of Cu and Mg (pieces / μm ² ), a 10,000 times field of view (about 120 μm ² / field of view) where the precipitation state of intermetallic compounds is not unique In this region, 10 fields of view (about 4.8 μm ² / field of view) were taken at a magnification of 50,000 times. 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 (piece / micrometer < ² >) of the intermetallic compound which has Cu and Mg as a main component with a particle size of 0.1 micrometer or more was calculated | required.

  Tables 1 and 2 show the conditions and evaluation results.

In Comparative Example 1 in which the Mg content is lower than the range of the present invention, the 0.2% proof stress was as low as 443 MPa or less.
In Comparative Example 2 in which the Mg content is higher than the range of the present invention, large ear cracks occurred during intermediate rolling, and it was impossible to perform subsequent characteristic evaluation.
Further, in Comparative Example 3 in which the content of at least one element of Pd and Ag is lower than the range of the present invention, the minimum bending radius ratio is 1.0, which is inferior in bending workability. That is confirmed.
Furthermore, in Comparative Example 4 in which the number of intermetallic compounds containing Cu and Mg as main components but not containing Pd and Ag is outside the scope of the present invention, the 0.2% proof stress is low, and the minimum bending radius The ratio is 4.0, confirming that the bending workability is greatly inferior.

  On the other hand, in Examples 1-8 of the present invention, 0.2% proof stress is 600 MPa or more and high proof stress, and the minimum bending radius ratio is 0.8 or less. Is good.

  From the above, according to the example of the present invention, there is provided a copper alloy for electronic equipment having high yield strength and excellent bending workability and suitable for electronic equipment parts such as terminals, connectors, relays, lead frames and the like. It was confirmed that

Claims (9)

Mg is included in the range of 3.3 atomic% to 6.9 atomic%, and at least one or more of Pd and Ag are included in the range of 0.1 atomic% to 5.0 atomic%, respectively. The balance is substantially Cu and inevitable impurities,
A copper alloy for electronic equipment, characterized in that, in observation with a scanning electron microscope, the average number of intermetallic compounds mainly composed of Cu and Mg having a particle diameter of 0.1 μm or more is 1 / μm ² or less . In the copper alloy for electronic devices according to claim 1,
A copper alloy for electronic equipment, characterized in that 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 minimum bending radius ratio (MBR / t) is 4 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 6.9 atomic%, and at least one or more of Pd and Ag are included in the range of 0.1 atomic% to 5.0 atomic%, respectively. A heating step of heating a copper material having a composition of which the balance is substantially Cu and inevitable impurities to 400 ° C. or more and 900 ° C. or less;
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 plastic processing of a rapidly cooled copper material;
The manufacturing method of the copper alloy for electronic devices characterized by the above-mentioned. 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 6.9 atomic%, and at least one or more of Pd and Ag are included in the range of 0.1 atomic% to 5.0 atomic%, respectively. A finishing process that plastically processes a copper material having a composition that is substantially Cu and inevitable impurities in a balance into a predetermined shape, and a finishing heat treatment process that performs a heat treatment after the finishing process. The manufacturing method of the copper alloy for electronic devices characterized by these. It consists of the copper alloy for electronic devices as described in any one of Claims 1-3, 0.2% yield strength (sigma) _0.2 shall be 400 Mpa or more, The copper alloy plasticity for electronic devices characterized by the above-mentioned Processed material.   A copper alloy plastic working material for electronic equipment, comprising the copper alloy for electronic equipment according to any one of claims 1 to 3 and having a minimum bending radius ratio (MBR / t) of 4 or less. . It consists of the copper alloy for electronic devices as described in any one of Claims 1-3,
A copper alloy plastic working material for electronic equipment, characterized in that it is used as a copper material constituting electronic equipment parts such as terminals, connectors, relays, and lead frames.   An electronic device component comprising the copper alloy for electronic devices according to any one of claims 1 to 3.

Images