JP7078091B2 - Copper alloys, copper alloy plastic processed materials, parts for electronic and electrical equipment, terminals, bus bars, lead frames, heat dissipation boards - Google Patents

Description

The present invention relates to a copper alloy suitable for electronic / electrical equipment parts such as terminals, bus bars, lead frames, and heat dissipation substrates, copper alloy plastic processed materials made of this copper alloy, electronic / electrical equipment parts, terminals, bus bars, and leads. It is related to the frame and heat dissipation board.

Conventionally, copper or a copper alloy having high conductivity has been used for electronic / electrical equipment parts such as terminals, bus bars, lead frames, and heat dissipation boards.
Here, in order to reduce the current density and dissipate heat due to Joule heat generation due to the increase in current of electronic devices and electric devices, the electronic and electric device parts used in these electronic devices and electric devices are used. , Pure copper material such as oxygen-free copper having excellent conductivity is applied.
However, the pure copper material has a problem that it has insufficient stress relaxation resistance and cannot be used in a high temperature environment.
Therefore, Patent Document 1 discloses a rolled copper plate containing Mg in a range of 0.005 mass% or more and less than 0.1 mass%.

In the copper rolled plate described in Patent Document 1, Mg is contained in the range of 0.005 mass% or more and less than 0.1 mass%, and the balance is composed of Cu and unavoidable impurities. By solid-dissolving in the matrix, it was possible to improve the stress relaxation resistance without significantly reducing the conductivity.

Japanese Unexamined Patent Publication No. 2016-056414

By the way, recently, in the copper material constituting the above-mentioned electronic / electrical equipment parts, it is used in order to sufficiently suppress heat generation when a large current is passed, and also in applications where pure copper material is used. It is required to further improve the conductivity so as to be possible. Further, by sufficiently improving the conductivity, it becomes possible to satisfactorily use the material even in the applications where the pure copper material has been conventionally used.
In addition, the above-mentioned electronic / electrical equipment parts are often used in high-temperature environments such as engine rooms, and the copper materials that make up electronic / electrical equipment parts have more stress-relief characteristics than before. Need to be improved.

The present invention has been made in view of the above-mentioned circumstances, and is a copper alloy having high conductivity and excellent stress resistance relaxation characteristics, a copper alloy plastic work material, parts for electronic / electrical equipment, terminals, bus bars, leads. The purpose is to provide a frame and a heat dissipation substrate.

As a result of diligent studies by the present inventors in order to solve this problem, in order to achieve both high conductivity and excellent stress relaxation resistance in a well-balanced manner, a small amount of Mg is added and a compound is produced with Mg. It became clear that it was necessary to regulate the content of elements. That is, by regulating the content of Mg and the element that forms the compound and allowing a trace amount of Mg to be present in the copper alloy in an appropriate form, the conductivity and stress relaxation resistance can be improved to a higher level than before. We obtained the knowledge that it is possible to improve in a well-balanced manner.

The present invention has been made based on the above findings, and the copper alloy of the present invention has a composition in which the Mg content is in the range of more than 10 mass ppm and less than 100 mass ppm, and the balance is Cu and unavoidable impurities. Among the unavoidable impurities, the S content is 10 mass ppm or less, the P content is 10 mass ppm or less, the Se content is 5 mass ppm or less, the Te content is 5 mass ppm or less, the Sb content is 5 mass ppm or less, and the Bi content is Bi. Is 5 mass ppm or less, the As content is 5 mass ppm or less, and the total content of S, P, Se, Te, Sb, Bi and As is 30 mass ppm or less, and the Mg content is [Mg]. When the total content of S, P, Se, Te, Sb, Bi, and As is [S + P + Se + Te + Sb + Bi + As], these mass ratios [Mg] / [S + P + Se + Te + Sb + Bi + As] are within the range of 0.6 or more and 50 or less. Each crystal has a conductivity of 97% IACS or more and a measurement area of 10000 μm ² or more by the EBSD method, except for measurement points where the CI value is 0.1 or less at the step of the measurement interval of 0.25 μm. The grain orientation difference is analyzed, and the grain boundary is defined as the grain boundary between the measurement points where the orientation difference between adjacent measurement points is 15 ° or more. The CI value analyzed by the data analysis software OIM is 0 in the measurement area of 10000 μm ² or more in multiple fields so that the measurement is performed in steps of measurement intervals of 1 or less and a total of 1000 or more crystal grains are included. KAM (Kernel Average Measurement) value when the orientation difference of each crystal grain is analyzed except for the measurement points of 1. or less, and the boundary where the orientation difference between adjacent pixels is 5 ° or more is regarded as the crystal grain boundary. It is characterized in that the average value of is 2.4 or less.

According to the copper alloy having this configuration, the contents of Mg and the elements S, P, Se, Te, Sb, Bi, and As that form a compound with Mg are defined as described above, so a small amount is added. By solidly dissolving the magnesium in the copper matrix, the stress resistance relaxation characteristics can be improved without significantly reducing the conductivity. Specifically, the conductivity can be set to 97% IACS or higher. can.
Since it is said that the average value of the KAM values is 2.4 or less, it is possible to improve the stress relaxation resistance characteristics while maintaining the strength.

Here, in the copper alloy of the present invention, it is preferable that the Ag content is in the range of 5 mass ppm or more and 20 mass ppm or less.
In this case, since Ag is contained in the above range, Ag segregates in the vicinity of the grain boundaries, the grain boundary diffusion is suppressed, and the stress relaxation resistance characteristics can be further improved.

Further, in the copper alloy of the present invention, it is preferable that the residual stress ratio RS _G (%) after holding at 200 ° C. for 4 hours in the direction parallel to the rolling direction is 20% or more.
In this case, the stress relaxation resistance is sufficiently excellent, and it is particularly suitable as a copper alloy constituting parts for electronic and electrical equipment used in a high temperature environment.

The copper alloy plastically processed material of the present invention is characterized by being made of the above-mentioned copper alloy.
According to the copper alloy plastic work material having this configuration, since it is composed of the above-mentioned copper alloy, it has excellent conductivity and stress resistance relaxation characteristics, and is used for high current applications, terminals and bus bars used in high temperature environments. , Especially suitable as a material for parts for electronic and electrical equipment such as lead frames and heat dissipation boards.

Here, in the copper alloy plastic working material of the present invention, a rolled plate having a thickness in the range of 0.1 mm or more and 10 mm or less may be used.
In this case, since the rolled plate has a thickness of 0.1 mm or more and 10 mm or less, the terminal, bus bar, and the like can be obtained by punching or bending the copper alloy plastically processed material (rolled plate). It is possible to mold parts for electronic and electrical equipment such as lead frames and heat dissipation boards.

Further, in the copper alloy plastic working material of the present invention, it is preferable to have a Sn plating layer or an Ag plating layer on the surface.
In this case, since it has a Sn plating layer or an Ag plating layer on the surface, it is particularly suitable as a material for parts for electronic and electrical equipment such as terminals, bus bars, lead frames, and heat dissipation boards. In the present invention, "Sn plating" includes pure Sn plating or Sn alloy plating, and "Ag plating" includes pure Ag plating or Ag alloy plating.

The parts for electronic and electrical equipment of the present invention are characterized by being made of the above-mentioned copper alloy plastic processed material. The parts for electronic / electrical equipment in the present invention include terminals, bus bars, lead frames, heat dissipation boards, and the like.
Since the parts for electronic and electrical equipment having this configuration are manufactured using the above-mentioned copper alloy plastic working material, they can exhibit excellent characteristics even in high current applications and high temperature environments.

The terminal of the present invention is characterized by being made of the above-mentioned copper alloy plastically worked material.
Since the terminal having this configuration is manufactured by using the above-mentioned copper alloy plastic working material, it can exhibit excellent characteristics even in a large current application and a high temperature environment.

The bus bar of the present invention is characterized by being made of the above-mentioned copper alloy plastically worked material.
Since the bus bar having this configuration is manufactured by using the above-mentioned copper alloy plastic working material, it can exhibit excellent characteristics even in a large current application and a high temperature environment.

The lead frame of the present invention is characterized by being made of the above-mentioned copper alloy plastically worked material.
Since the lead frame having this configuration is manufactured by using the above-mentioned copper alloy plastic working material, it can exhibit excellent characteristics even in a large current application and a high temperature environment.

The heat radiating substrate of the present invention is characterized in that it is manufactured by using the above-mentioned copper alloy.
Since the heat dissipation substrate having this configuration is manufactured by using the above-mentioned copper alloy, it can exhibit excellent characteristics even in a large current application and a high temperature environment.

According to the present invention, it is possible to provide copper alloys, copper alloy plastic processed materials, parts for electronic and electrical equipment, terminals, bus bars, lead frames, and heat dissipation substrates having high conductivity and excellent stress resistance relaxation properties. Become.

It is a flow chart of the manufacturing method of the copper alloy which is this embodiment.

Hereinafter, a copper alloy according to an embodiment of the present invention will be described.
The copper alloy of the present embodiment has a composition in which the Mg content is in the range of more than 10 mass ppm and less than 100 mass ppm, and the balance is Cu and unavoidable impurities. Among the unavoidable impurities, the S content is 10 mass ppm or less. The P content is 10 mass ppm or less, the Se content is 5 mass ppm or less, the Te content is 5 mass ppm or less, the Sb content is 5 mass ppm or less, the Bi content is 5 mass ppm or less, and the As content is 5 mass ppm or less. At the same time, the total content of S, P, Se, Te, Sb, Bi and As is 30 mass ppm or less.

When the content of Mg is [Mg] and the total content of S, P, Se, Te, Sb, Bi and As is [S + P + Se + Te + Sb + Bi + As], the mass ratios [Mg] / [S + P + Se + Te + Sb + Bi + As] are It is within the range of 0.6 or more and 50 or less.
In the copper alloy of this embodiment, the Ag content may be in the range of 5 mass ppm or more and 20 mass ppm or less.

Further, in the copper alloy of this embodiment, the conductivity is 97% IACS or more.
Further, in the copper alloy of the present embodiment, it is preferable that the residual stress ratio RS _G (%) after holding at 200 ° C. for 4 hours in the direction parallel to the rolling direction is 20% or more.

Then, in the copper alloy of the present embodiment, each crystal grain has a measurement area of 10,000 μm ² or more by the EBSD method, except for measurement points where the CI value is 0.1 or less in the step of the measurement interval of 0.25 μm. The average particle size A is obtained by Area Fraction, with the crystal grain boundary between the measurement points where the orientation difference between adjacent measurement points is 15 ° or more, and 1/10 of the average particle size A. The CI value analyzed by the data analysis software OIM is ⁰ . The KAM (Kernel Area Measurement) value when the orientation difference of each crystal grain is analyzed except for the measurement points of 1 or less and the boundary where the orientation difference between adjacent pixels is 5 ° or more is regarded as the crystal grain boundary. The average value is 2.4 or less.

Here, in the copper alloy of the present embodiment, the reasons for defining the component composition, structure, and various characteristics as described above will be described below.

(Mg)
Mg is an element having an action effect of improving strength and stress relaxation resistance characteristics by being solid-solved in the parent phase of copper without significantly lowering the conductivity. Further, by dissolving Mg in the matrix phase, the heat resistance is also improved.
Here, when the Mg content is 10 mass ppm or less, there is a possibility that the action and effect cannot be fully exerted. On the other hand, when the Mg content is 100 mass ppm or more, the conductivity may decrease.
From the above, in the present embodiment, the Mg content is set within the range of more than 10 mass ppm and less than 100 mass ppm.

In order to further improve the stress relaxation resistance, the lower limit of the Mg content is preferably 20 mass ppm or more, more preferably 30 mass ppm or more, and even more preferably 40 mass ppm or more.
Further, in order to further suppress the decrease in conductivity, the upper limit of the Mg content is preferably less than 90 mass ppm, more preferably less than 80 mass ppm, and even more preferably less than 70 mass ppm.

(S, P, Se, Te, Sb, Bi, As)
The above-mentioned elements such as S, P, Se, Te, Sb, Bi, and As are generally elements that are easily mixed in the copper alloy. Then, these elements easily react with Mg to form a compound, and there is a possibility that the solid solution effect of Mg added in a small amount may be reduced. Therefore, it is necessary to strictly control the content of these elements.
Therefore, in the present embodiment, the S content is 10 mass ppm or less, the P content is 10 mass ppm or less, the Se content is 5 mass ppm or less, the Te content is 5 mass ppm or less, the Sb content is 5 mass ppm or less, and Bi. The content is limited to 5 mass ppm or less, and the content of As is limited to 5 mass ppm or less.
Further, the total content of S, P, Se, Te, Sb, Bi and As is limited to 30 mass ppm or less.

The content of S is preferably 9 mass ppm or less, and more preferably 8 mass ppm or less.
The content of P is preferably 6 mass ppm or less, and more preferably 3 mass ppm or less.
The content of Se is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.
The content of Te is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.
The content of Sb is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.
The Bi content is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.
The content of As is preferably 4 mass ppm or less, and more preferably 2 mass ppm or less.
Further, the total content of S, P, Se, Te, Sb, Bi and As is preferably 24 mass ppm or less, and more preferably 18 mass ppm or less.

([Mg] / [S + P + Se + Te + Sb + Bi + As])
As described above, elements such as S, P, Se, Te, Sb, Bi, and As easily react with Mg to form a compound. Therefore, in the present embodiment, the Mg content and S and P are used. By defining the ratio of Se, Te, Sb, Bi, and the total content of As, the existence form of Mg is controlled.
When the content of Mg is [Mg] and the total content of S, P, Se, Te, Sb, Bi and As is [S + P + Se + Te + Sb + Bi + As], these mass ratios [Mg] / [S + P + Se + Te + Sb + Bi + As] are 50. If it exceeds, Mg is present in the copper in an excessively solid-dissolved state, and the conductivity may decrease. On the other hand, if the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] is less than 0.6, Mg is not sufficiently dissolved and the stress relaxation resistance may not be sufficiently improved.
Therefore, in the present embodiment, the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] is set within the range of 0.6 or more and 50 or less.

In order to further suppress the decrease in conductivity, the upper limit of the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] is preferably 35 or less, and more preferably 25 or less.
Further, in order to further improve the stress relaxation resistance, the lower limit of the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] is preferably 0.8 or more, and more preferably 1.0 or more.

(Ag: 5 mass ppm or more and 20 mass ppm or less)
Ag can hardly be dissolved in the parent phase of Cu in the operating temperature range of ordinary electronic / electrical equipment of 250 ° C. or lower. Therefore, Ag added in a small amount to copper will segregate in the vicinity of the grain boundaries. As a result, the movement of atoms at the grain boundaries is hindered and the grain boundary diffusion is suppressed, so that the stress relaxation resistance characteristics are improved.
Here, when the content of Ag is 5 mass ppm or more, the action and effect can be fully exerted. On the other hand, when the Ag content is 20 mass ppm or less, the conductivity can be ensured and the increase in manufacturing cost can be suppressed.
From the above, in the present embodiment, the Ag content is set within the range of 5 mass ppm or more and 20 mass ppm or less.

In order to further improve the stress relaxation resistance, the lower limit of the Ag content is preferably 6 mass ppm or more, more preferably 7 mass ppm or more, and even more preferably 8 mass ppm or more. Further, in order to surely suppress the decrease in conductivity and the increase in cost, the upper limit of the Ag content is preferably 18 mass ppm or less, more preferably 16 mass ppm or less, and more preferably 14 mass ppm or less. preferable.
Further, when Ag is not intentionally contained but contained as an impurity, the content of Ag may be less than 5 mass ppm.

(Other unavoidable impurities)
Other unavoidable impurities other than the above-mentioned elements include Al, B, Ba, Be, Ca, Cd, Cr, Sc, rare earth elements, V, Nb, Ta, Mo, Ni, W, Mn, Re, Ru, Examples thereof include Sr, Ti, Os, Co, Rh, Ir, Pb, Pd, Pt, Au, Zn, Zr, Hf, Hg, Ga, In, Ge, Y, Tl, N, Si, Sn, Li and the like. These unavoidable impurities may be contained within a range that does not affect the characteristics.
Here, since these unavoidable impurities may lower the conductivity, the total amount is preferably 0.1 mass% or less, more preferably 0.05 mass% or less, and 0.03 mass% or less. It is more preferable to set it to 0.01 mass% or less.
The upper limit of the content of each of these unavoidable impurities is preferably 10 mass ppm or less, more preferably 5 mass ppm or less, and even more preferably 2 mass ppm or less.

(Conductivity: 97% IACS or higher)
In the copper alloy of this embodiment, the conductivity is 97% IACS or more. By setting the conductivity to 97% IACS or higher, it is possible to suppress heat generation during energization and use it as a substitute for pure copper materials as parts for electronic and electrical equipment such as terminals, bus bars, lead frames, and heat dissipation boards. It becomes.
The conductivity is preferably 97.5% IACS or higher, more preferably 98.0% IACS or higher, more preferably 98.5% IACS or higher, and 99.0% IACS or higher. It is even more preferable to have.

(Residual stress rate RS _G (%): 20% or more after holding at 200 ° C. for 4 hours in the direction parallel to the rolling direction)
In the copper alloy of the present embodiment, it is preferable that the residual stress ratio RS _G (%) after holding at 200 ° C. for 4 hours in the direction parallel to the rolling direction is 20% or more.
When the residual stress ratio under this condition is high, the permanent deformation can be suppressed to a small value even when used in a high temperature environment, and the decrease in contact pressure can be suppressed. Therefore, the copper alloy of the present embodiment is particularly suitable as a terminal used in a high temperature environment such as around the engine room of an automobile.
The residual stress ratio RS _G (%) after holding at 200 ° C. for 4 hours in the direction parallel to the rolling direction is more preferably 30% or more, more preferably 40% or more, and more preferably 50% or more. Is even more preferable.

(Average value of KAM value: 2.4 or less)
The KAM (Kernel Average Measurement) value measured by EBSD is a value calculated by averaging the azimuth difference between one pixel and the pixels surrounding it. Since the shape of the pixel is a regular hexagon, when the proximity order is 1 (1st), the average value of the directional differences with the six adjacent pixels is calculated as the KAM value. By using this KAM value, it is possible to visualize the local directional difference, that is, the distribution of strain.

Since this region having a high KAM value is a region where the density of dislocations (GN dislocations) introduced during processing is high, high-speed diffusion of atoms through the dislocations is likely to occur, and stress relaxation is likely to occur. Therefore, by controlling the average value of the KAM value to 2.4 or less, it is possible to improve the stress relaxation resistance while maintaining the strength.
The average value of the KAM value is preferably 2.2 or less, more preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.6 or less, even within the above range. On the other hand, the lower limit of the average value of the KAM value is not particularly limited, but in order to secure the work hardening amount and obtain sufficient strength, the average value of the KAM value is more preferably 0.2 or more, and is 0. It is more preferably 0.4 or more, further preferably 0.6 or more, and most preferably 0.8 or more.

In this embodiment, the KAM value is used except for the measurement points where the CI (Confidence Index) value, which is the value measured by the analysis software OIM Analysis (Ver. 7.3.1) of the EBSD device, is 0.1 or less. It is calculated. The CI value is calculated by using the Voting method when indexing the EBSD pattern obtained from a certain analysis point, and takes a value of 0 to 1. Since the CI value is a value that evaluates the reliability of indexing and orientation calculation, strain (processed structure) exists in the structure when the CI value is low, that is, when a clear crystal pattern at the analysis point cannot be obtained. It can be said that it is doing. When the strain is particularly large, the CI value is 0.1 or less.

Next, a method for manufacturing a copper alloy according to the present embodiment having such a configuration will be described with reference to the flow chart shown in FIG.

(Melting / Casting Step S01)
First, the above-mentioned elements are added to the molten copper obtained by melting the copper raw material to adjust the components to produce a molten copper alloy. In addition, a simple substance of an element, a mother alloy, or the like can be used for adding various elements. Further, the raw material containing the above-mentioned elements may be dissolved together with the copper raw material. Further, the recycled material and the scrap material of the present alloy may be used.
Here, the copper raw material is preferably a so-called 4NCu having a purity of 99.99 mass% or more, or a so-called 5 NCu having a purity of 99.999 mass% or more.

At the time of dissolution, in order to suppress the oxidation of Mg and to reduce the hydrogen concentration, the atmosphere is dissolved in an inert gas atmosphere (for example, Ar gas) in which the vapor pressure of _H2O is low, and the retention time at the time of dissolution is the minimum. It is preferable to keep it to the limit.
Then, a molten copper alloy whose composition has been adjusted is injected 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.

(Homogenization / solutionization step S02)
Next, heat treatment is performed for homogenization and solution formation of the obtained ingot. Inside the ingot, there may be an intermetallic compound containing Cu and Mg as main components, which is generated by the concentration of Mg by segregation in the process of solidification. Therefore, in order to eliminate or reduce these segregation and intermetallic compounds, Mg is uniformly diffused in the ingot by performing a heat treatment in which the ingot is heated to 300 ° C. or higher and 1080 ° C. or lower. , Mg is dissolved in the matrix. The homogenization / solution step S02 is preferably carried out in a non-oxidizing or reducing atmosphere.

Here, if the heating temperature is less than 300 ° C., solution formation may be incomplete, and a large amount of intermetallic compounds containing Cu and Mg as main components may remain in the matrix phase. On the other hand, if the heating temperature exceeds 1080 ° C., a part of the copper material becomes a liquid phase, and the structure and surface condition may become non-uniform. Therefore, the heating temperature is set in the range of 300 ° C. or higher and 1080 ° C. or lower.
In order to improve the efficiency of rough rolling and to make the structure uniform, which will be described later, hot working may be performed after the above-mentioned homogenization / solutionization step S02. In this case, the processing method is not particularly limited, and for example, rolling, drawing, extrusion, groove rolling, forging, pressing, or the like can be adopted. The hot working temperature is preferably in the range of 300 ° C. or higher and 1080 ° C. or lower.

(Roughing process S03)
Roughing is performed in order to process into a predetermined shape. The temperature conditions in this roughing step S03 are not particularly limited, but are within the range of −200 ° C. to 200 ° C. for cold or warm rolling in order to suppress recrystallization or improve dimensional accuracy. Is preferable, and room temperature is particularly preferable. The processing rate is preferably 20% or more, more preferably 30% or more. The processing method is not particularly limited, and for example, rolling, drawing, extrusion, groove rolling, forging, pressing, or the like can be adopted.

(Intermediate heat treatment step S04)
After the roughing step S03, a heat treatment is performed to obtain a recrystallized structure. The intermediate heat treatment step S04 and the upper preprocessing step S05, which will be described later, may be repeated.
Here, since this intermediate heat treatment step S04 is substantially the final recrystallization heat treatment, the crystal grain size of the recrystallized structure obtained in this step is substantially equal to the final crystal grain size. Therefore, in this intermediate heat treatment step S04, it is preferable to appropriately select the heat treatment conditions so that the average crystal grain size is 5 μm or more. For example, at 700 ° C., it is preferably held for about 1 to 120 seconds.

(Upper pre-processing process S05)
In order to process the copper material after the intermediate heat treatment step S04 into a predetermined shape, upper preprocessing is performed. The temperature conditions in the pre-processing step S05 are not particularly limited, but cold or warm processing is performed in order to suppress recrystallization during processing or to suppress softening, and the temperature is −200 ° C. to 200 ° C. It is preferable that the temperature is within the above range, and room temperature is particularly preferable. The work ratio is appropriately selected so as to be close to the final shape, but is preferably 5% or more in order to improve the strength by work hardening. On the other hand, in order to suppress an excessive increase in the KAM value, the processing rate is preferably 85% or less, and more preferably 80% or less.
The processing method is not particularly limited, and for example, rolling, drawing, extrusion, groove rolling, forging, pressing, or the like can be adopted.

(Mechanical surface treatment step S06)
After the upper pre-processing step S05, a mechanical surface treatment is performed. The mechanical surface treatment is a treatment in which compressive stress is applied to the vicinity of the surface after a desired shape is almost obtained, and has an effect of improving stress relaxation resistance.
Mechanical surface treatment includes shot peening treatment, blasting treatment, lapping treatment, polishing treatment, buffing, grinder polishing, sandpaper polishing, tension leveler treatment, and light rolling with low reduction rate per pass (reduction rate per pass). Various commonly used methods such as 1 to 10% and repeated 3 times or more can be used.
By adding this mechanical surface treatment to the copper alloy to which Mg is added, the stress relaxation resistance characteristics are greatly improved.

(Finishing heat treatment step S07)
Next, the plastic processed material obtained in the mechanical surface treatment step S06 is subjected to a finish heat treatment in order to segregate the contained elements into the grain boundaries and remove residual strain.
The heat treatment temperature is preferably in the range of 100 ° C. or higher and 500 ° C. or lower. In this finish heat treatment step S07, the heat treatment conditions are such that the dislocation arrangement is optimized by removing the residual strain and the excessively increased KAM value is reduced so as to avoid a significant decrease in strength due to recrystallization. Need to be set. For example, it is preferably held at 450 ° C. for about 0.1 to 10 seconds, and at 250 ° C. for 1 minute to 100 hours. This heat treatment is preferably performed in a non-oxidizing atmosphere or a reducing atmosphere. The heat treatment method is not particularly limited, but a short-time heat treatment using a continuous annealing furnace is preferable from the viewpoint of reducing the manufacturing cost.
Further, the above-mentioned upper pre-processing step S05, mechanical surface treatment step S06, and finish heat treatment step S07 may be repeatedly performed.

In this way, the copper alloy (copper alloy plastically processed material) according to the present embodiment is produced. The copper alloy plastically processed material produced by rolling is called a copper alloy rolled plate.
Here, when the plate thickness of the copper alloy plastic working material is 0.1 mm or more, it is suitable for use as a conductor in a large current application. Further, by setting the plate thickness of the copper alloy plastic working material to 10.0 mm or less, it is possible to suppress an increase in the load of the press machine, secure productivity per unit time, and suppress manufacturing costs. ..
Therefore, the plate thickness of the plastically processed copper alloy material (rolled copper alloy material) is preferably in the range of 0.1 mm or more and 10.0 mm or less.
The lower limit of the plate thickness of the copper alloy plastically worked material (copper alloy rolled material) is preferably 0.5 mm or more, and more preferably 1.0 mm or more. On the other hand, the upper limit of the plate thickness of the copper alloy plastically worked material (copper alloy rolled material) is preferably less than 9.0 mm, more preferably less than 8.0 mm.

In the copper alloy of the present embodiment having the above-mentioned structure, the Mg content is in the range of more than 10 mass ppm and less than 100 mass ppm, and the content of S, which is an element that forms a compound with Mg, is 10 mass ppm or less. The P content is 10 mass ppm or less, the Se content is 5 mass ppm or less, the Te content is 5 mass ppm or less, the Sb content is 5 mass ppm or less, the Bi content is 5 mass ppm or less, the As content is 5 mass ppm or less, and further. Since the total content of S, P, Se, Te, Sb, Bi and As is limited to 30 mass ppm or less, Mg added in a small amount can be dissolved in the copper matrix, and the conductivity is greatly reduced. It is possible to improve the stress resistance relaxation characteristics without causing the problem.

When the content of Mg is [Mg] and the total content of S, P, Se, Te, Sb, Bi and As is [S + P + Se + Te + Sb + Bi + As], these mass ratios [Mg] / [S + P + Se + Te + Sb + Bi + As] are set. Since it is set in the range of 0.6 or more and 50 or less, it is possible to sufficiently improve the stress relaxation resistance characteristics without excessively dissolving Mg in a solid solution and lowering the conductivity. Therefore, according to the copper alloy of the present embodiment, the conductivity is 97% IACS or more, and the residual stress rate RS _G (%) after holding at 200 ° C. for 4 hours in the direction parallel to the rolling direction is 20% or more. It is possible to achieve both high conductivity and excellent stress relaxation resistance.
Further, in the present embodiment, since the average value of the KAM values is 2.4 or less, it is possible to improve the stress relaxation resistance characteristics while maintaining the strength.

In the present embodiment, when the Ag content is in the range of 5 mass ppm or more and 20 mass ppm or less, Ag segregates in the vicinity of the grain boundaries, the grain boundary diffusion is suppressed, and the stress relaxation resistance is improved. It will be possible.

Since the copper alloy plastic working material of the present embodiment is composed of the above-mentioned copper alloy, it has excellent conductivity and stress relaxation resistance, and is electronically and electrically used for terminals, bus bars, lead frames, heat dissipation substrates, and the like. Especially suitable as a material for equipment parts.
Further, when the copper alloy plastically processed material of the present embodiment is a rolled plate having a thickness of 0.1 mm or more and 10 mm or less, the copper alloy plastically processed material (rolled plate) is punched or punched. By bending, parts for electronic and electrical equipment such as terminals, bus bars, lead frames, and heat dissipation boards can be molded relatively easily.
When a Sn plating layer or an Ag plating layer is formed on the surface of the copper alloy plastically processed material of the present embodiment, it is particularly used as a material for electronic / electrical equipment parts such as terminals, bus bars, lead frames, and heat dissipation substrates. Are suitable.

Further, since the electronic / electrical equipment parts (terminals, bus bars, lead frames, heat dissipation boards, etc.) of the present embodiment are made of the above-mentioned copper alloy plastic processed material, they can be used in high currents and in high temperature environments. , Can exhibit excellent characteristics.

Although the copper alloy, the copper alloy plastic processed material, and the parts for electronic / electrical equipment (terminals, bus bars, lead frames, heat dissipation boards) which are the embodiments of the present invention have been described above, the present invention is not limited thereto. It can be changed 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 (copper alloy plastic processed material) has been described, but the method for manufacturing a copper alloy is not limited to that described in the embodiment, and is not limited to the existing method. The production method may be appropriately selected for production.

The results of the confirmation experiment conducted to confirm the effect of the present invention will be described below.
By the band melting purification method, a raw material made of pure copper having a purity of 99.999 mass% or more was charged into a high-purity graphite crucible and melted at high frequency in an atmosphere furnace having an Ar gas atmosphere.

Various 0.1 mass% mother alloys prepared using high-purity copper having a purity of 6N (purity 99.9999 mass%) or more and a pure metal having a purity of 2N (purity 99 mass%) or more are added to the obtained molten copper. The components were adjusted and poured into a heat insulating material (isowool) mold to produce ingots having the component compositions shown in Tables 1 and 2. The size of the ingot was about 30 mm in thickness × about 60 mm in width × about 150 to 200 mm in length.

The obtained ingot was heated at 900 ° C. for 1 hour in an Ar gas atmosphere to dissolve Mg, and surface grounded to remove the oxide film to a predetermined size. I made a disconnection.
Then, the thickness was adjusted so as to be the final thickness as appropriate, and cutting was performed. Each of the cut samples was roughly rolled under the conditions shown in Tables 3 and 4, and then subjected to an intermediate heat treatment under the condition that the crystal grain size was about 30 μm by recrystallization.

Next, the upper pre-rolling (upper pre-machining step) was carried out under the conditions shown in Tables 3 and 4.
Then, these samples were subjected to a mechanical surface treatment step by the methods shown in Tables 3 and 4.
The sandpaper polishing was performed using # 240 polishing paper.
The lapping process was carried out using SiC-based abrasive grains and a cast iron wrap.
The shot peening treatment was carried out using a stainless steel shot having a diameter of 0.2 mm at a projection speed of 10 m / sec and a projection time of 5 seconds.
Then, the finish heat treatment was performed under the conditions shown in Tables 3 and 4, and the strips having a thickness × width of about 60 mm shown in Tables 3 and 4, respectively, were produced.

The following items were evaluated for the obtained strips.

(Composition analysis)
A measurement sample was taken from the obtained ingot, Mg was measured by inductively coupled plasma emission spectroscopy, and other elements were measured using a glow discharge mass spectrometer (GD-MS). The measurement was performed at two points, the center of the sample and the end in the width direction, and the one with the higher content was taken as the content of the sample. As a result, it was confirmed that the composition was as shown in Tables 1 and 2.

(conductivity)
A test piece having a width of 10 mm and a length of 60 mm was sampled from a strip for character evaluation, and the electrical resistance was determined by the 4-terminal method. In addition, the dimensions of the test piece were measured using a micrometer, and the volume of the test piece was calculated. Then, the conductivity was calculated from the measured electric resistance value and volume. The test pieces were collected so that the longitudinal direction thereof was parallel to the rolling direction of the strip material for character evaluation. The evaluation results are shown in Tables 3 and 4.

(KAM value)
With the rolled surface, that is, the ND surface (Normal direction) as the observation surface, the average value of the KAM values was obtained as follows by the EBSD measuring device and the OIM analysis software.
After mechanical polishing using water-resistant abrasive paper and diamond abrasive grains, finish polishing was performed using a colloidal silica solution. Then, the EBSD measuring device (Quanta FEG 450 manufactured by FEI, OIM Data Collection manufactured by EDAX / TSL (currently AMETEK)) and the analysis software (EDAX / TSL (currently AMETEK) OIM Data Analysis ver.7.3). According to 1), the measurement area of the electron beam acceleration voltage of 15 kV, 10,000 μm ² or more, and the orientation difference of each crystal grain except for the measurement points where the CI value is 0.1 or less at the step of the measurement interval of 0.25 μm. The average particle size A by Area Fraction was determined using the data analysis software OIM, with the crystal grain boundary between the measurement points where the orientation difference between the adjacent measurement points is 15 ° or more. After that, measurement is performed at a measurement interval step of 1/10 or less of the average particle size A, and data analysis is performed with a measurement area of 10000 μm ² or more in a plurality of visual fields so that a total of 1000 or more crystal grains are included. KAM of all pixels analyzed except for measurement points where the CI value analyzed by soft OIM is 0.1 or less, and the boundary where the orientation difference between adjacent pixels is 5 ° or more is regarded as a grain boundary. The value was calculated, and the average value was calculated.

(Stress relaxation resistance)
The stress relaxation resistance property test conforms to the Japan Copper and Brass Association technical standard JCBA-T309: 2004, stress is applied by a method conforming to the cantilever beam type, and the residual stress rate after holding at a temperature of 200 ° C. for 4 hours. Was measured. The evaluation results are shown in Tables 3 and 4.
As a test method, a test piece (width 10 mm) is collected from each characteristic evaluation strip in a direction parallel to the rolling direction, and the initial deflection displacement is set so that the maximum surface stress of the test piece is 80% of the proof stress. The span length was adjusted by setting it to 2 mm. The maximum surface stress is determined by the following equation.
Maximum surface stress (MPa) = 1.5Etδ ₀ / L _s ²
however,
E: Young's modulus (MPa)
t: Sample thickness (mm)
δ ₀ : Initial deflection displacement (mm)
L _s : Span length (mm)
Is.
The proof stress used here was determined by collecting the No. 13B test piece specified in JIS Z 2241 from the characterization material and measuring the 0.2% proof stress by the offset method of JIS Z 2241.

The residual stress ratio RS _G (%) was measured from the bending habit after holding for 4 hours at a temperature of 200 ° C., and the stress relaxation resistance characteristics were evaluated. The residual stress rate RS _G (%) was calculated using the following equation.
Residual stress rate RS _G (%) = (1-δ _t / δ ₀ ) × 100
however,
δ _t : Permanent deflection displacement after holding at 200 ° C for 4 hours (mm) -Permanent deflection displacement after holding at room temperature for 24 hours (mm)
δ ₀ : Initial deflection displacement (mm)
Is.

(Mechanical characteristics)
The No. 13B test piece specified in JIS Z 2241 was collected from the characterization material, and the tensile strength was measured by the offset method of JIS Z 2241. The test piece was collected in a direction parallel to the rolling direction. The evaluation results are shown in Tables 3 and 4.

In Comparative Example 1, since the Mg content was less than the range of the present invention, the residual stress ratio was low and the stress relaxation resistance was insufficient.
In Comparative Example 2, the Mg content was beyond the range of the present invention, and the conductivity was low.
In Comparative Example 3, the total contents of S, P, Se, Te, Sb, Bi, and As exceeded 30 mass ppm, the residual stress ratio was low, and the stress relaxation resistance was insufficient.
In Comparative Example 4, the mass ratio [Mg] / [S + P + Se + Te + Sb + Bi + As] was less than 0.6, the residual stress ratio was low, and the stress relaxation resistance was insufficient.
In Comparative Example 5, the average value of KAM values exceeded 2.4, the residual stress rate was low, and the stress relaxation resistance characteristics were insufficient.

On the other hand, in Examples 1 to 24 of the present invention, it was confirmed that the conductivity and the stress relaxation resistance were improved in a well-balanced manner.

Claims (11)

The composition has a composition in which the Mg content is in the range of more than 10 mass ppm and less than 100 mass ppm, and the balance is Cu and unavoidable impurities. Among the unavoidable impurities, the S content is 10 mass ppm or less, the P content is 10 mass ppm or less, and Se. The content is 5 mass ppm or less, the Te content is 5 mass ppm or less, the Sb content is 5 mass ppm or less, the Bi content is 5 mass ppm or less, the As content is 5 mass ppm or less, and S, P, Se, and Te. The total content of Sb, Bi and As is 30 mass ppm or less.
When the content of Mg is [Mg] and the total content of S, P, Se, Te, Sb, Bi and As is [S + P + Se + Te + Sb + Bi + As], the mass ratios [Mg] / [S + P + Se + Te + Sb + Bi + As] are 0. It is said to be within the range of 6 or more and 50 or less.
Conductivity is 97% IACS or higher,
By the EBSD method, the measurement area of 10000 μm ² or more is analyzed for the orientation difference of each crystal grain except for the measurement points where the CI value is 0.1 or less in the step of the measurement interval of 0.25 μm, and the adjacent measurement points are analyzed. The crystal grain boundary is defined as the measurement point where the orientation difference between them is 15 ° or more, the average particle size A is obtained by Area Fraction, and the measurement is performed at the step of the measurement interval which is 1/10 or less of the average particle size A. Each crystal grain except for the measurement points where the CI value analyzed by the data analysis software OIM is 0.1 or less in the measurement area of 10,000 μm ² or more in multiple fields so that a total of 1000 or more crystal grains are included. The average value of the KAM (Kernel Average Measurement) value is 2.4 or less when the boundary where the orientation difference between adjacent pixels is 5 ° or more is regarded as the crystal grain boundary. A copper alloy characterized by. The copper alloy according to claim 1, wherein the content of Ag is in the range of 5 mass ppm or more and 20 mass ppm or less. The copper alloy according to claim 1 or 2, wherein the residual stress ratio RS _G (%) after holding at 200 ° C. for 4 hours in a direction parallel to the rolling direction is 20% or more. A copper alloy plastically worked material comprising the copper alloy according to any one of claims 1 to 3. The copper alloy plastically worked material according to claim 4, wherein the rolled plate has a thickness of 0.1 mm or more and 10 mm or less. The copper alloy plastic working material according to claim 4 or 5, wherein the surface thereof has a Sn plating layer or an Ag plating layer. A component for electronic / electrical equipment, which comprises the copper alloy plastic working material according to any one of claims 4 to 6. A terminal made of the copper alloy plastically worked material according to any one of claims 4 to 6. A bus bar made of the copper alloy plastically worked material according to any one of claims 4 to 6. A lead frame made of the copper alloy plastically worked material according to any one of claims 4 to 6. A heat-dissipating substrate made by using the copper alloy according to any one of claims 1 to 3.

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