JP2014055347A - Copper alloy sheet excellent in conductivity and stress relief properties - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy sheet having high strength, high conductivity and excellent in stress relief properties, to provide a method of manufacturing the copper alloy sheet and to provide an electronic component for a large current and an electronic component for heat release using the copper alloy sheet.SOLUTION: The copper alloy sheet contains Zn of 2 to 22 mass% and the remainder copper with its inevitable impurities, has a conductivity of 30% IACS or more and a 0.2% bearing force of 350 MPa or more, and a stress relief rate after adding stress of 80% of the 0.2% bearing force and maintaining at 150°C for 1000 hours of 50% or less.

Description

  The present invention relates to a copper alloy plate and electronic parts for energization or heat dissipation, and in particular, electronic devices such as terminals, connectors, relays, switches, sockets, bus bars, lead frames, heat sinks, etc. mounted on electric machines / electronic devices, automobiles, etc. The present invention relates to a copper alloy plate used as a component material and an electronic component using the copper alloy plate. Among them, copper alloys suitable for use in high current electronic parts such as connectors and terminals for large currents used in electric cars, hybrid cars, etc., or for use in electronic parts for heat dissipation such as liquid crystal frames used in smartphones and tablet PCs The present invention relates to a plate and an electronic component using the copper alloy plate.

Parts such as terminals, connectors, switches, sockets, relays, bus bars, lead frames, heat sinks, etc., that transmit electricity or heat are built into automobiles, electrical equipment, electronic devices, etc., and these parts are made of copper alloy. It is used. Here, electrical conductivity and thermal conductivity are in a proportional relationship.
In recent years, with the miniaturization of electronic components, the cross-sectional area of the copper alloy in the current-carrying part tends to be small. When the cross-sectional area becomes small, heat generation from the copper alloy when energized increases. In addition, some electronic parts used in an electric vehicle and a hybrid electric vehicle that are remarkably growing, such as a connector of a battery part, allow a very high current to flow, and heat generation of a copper alloy during energization is a problem.

In an electrical contact of an electronic component such as a connector, a deflection is given to the copper alloy plate, and a contact force at the contact is obtained by a stress generated by the deflection. When a bent copper alloy is held at a high temperature for a long time, the stress, that is, the contact force is reduced due to the stress relaxation phenomenon, and the contact electric resistance is increased.
Therefore, in order to cope with the problem of heat generation, the copper alloy is required to be superior in conductivity so that the amount of heat generation is reduced, and further to be excellent in stress relaxation characteristics so that the contact force does not decrease even if heat is generated. ing.
On the other hand, for example, a heat radiating component called a liquid crystal frame is used for a liquid crystal of a smartphone or a tablet PC. Even in such a copper alloy plate for heat dissipation, when stress relaxation characteristics are enhanced, creep deformation of the heat sink due to external force is suppressed, and the protection against liquid crystal components, IC chips, etc. disposed around the heat sink is improved. , Etc. can be expected. For this reason, it is desired that the copper alloy plate for heat dissipation also has excellent stress relaxation characteristics.

  As a copper alloy having relatively high electrical conductivity and strength and capable of being manufactured at low cost, red copper (Cu—Zn alloy) is known. For example, JSI alloy numbers C2100 (Cu-5 mass% Zn), C2200 (Cu— 10 mass% Zn), C2300 (Cu-15 mass% Zn), C2400 (Cu-20 mass% Zn), etc. are provided for practical use. Further, for example, Patent Document 1 discloses an alloy in which Sn is added to a Cu—Zn alloy to improve the strength.

JP 2007-046159 A

  The stress relaxation characteristics of the copper alloy can be improved by adding a specific alloy element. Examples of the element having a remarkable stress relaxation improving effect include Zr and Ti. However, since these elements are extremely active, some of them are oxidized during ingot melting. When this oxide is caught in an ingot, the surface of the product is damaged or the material being rolled is cut. Moreover, since these elements form precipitates in solid copper and the mechanical characteristics and stress relaxation characteristics change depending on the form of precipitation, it is necessary to strictly adjust the conditions for hot rolling and each heat treatment. As described above, the improvement of the stress relaxation characteristic by adding the alloy element generally causes a significant increase in the manufacturing cost of the copper alloy.

  Therefore, if the stress relaxation characteristics of the copper alloy can be improved by adjusting the manufacturing process without depending on the addition of alloy elements, it can be said that it is extremely significant industrially.

  Therefore, an object of the present invention is to provide a copper alloy having high strength, high conductivity, and excellent stress relaxation properties. Specifically, the present invention is an inexpensive Cu-Zn alloy that is excellent in conductivity and strength. It is an object to improve stress relaxation characteristics. Furthermore, another object of the present invention is to provide a method for producing the copper alloy plate and an electronic component suitable for high current use or heat dissipation use.

The present inventors have found that, in a Cu—Zn-based alloy, the stress relaxation characteristics are improved by adjusting the metal structure using the spring limit value as an index and controlling the orientation of crystal grains oriented on the rolling surface. It was.
Based on the above findings, the following invention has been completed.
(1) It contains 2 to 22% by mass of Zn, the balance is made of copper and its inevitable impurities, has a conductivity of 30% IACS or more, a 0.2% proof stress of 350 MPa or more, and 0. A copper alloy sheet, wherein a stress relaxation rate after applying 80% stress of 2% proof stress and holding at 150 ° C. for 1000 hours is 50% or less.
(2) The copper alloy according to (1), wherein the relationship between the spring limit value Kb (MPa) and the 0.2% yield strength σ (MPa) is given by Kb ≧ (σ−100) Board.
(3) When the integrated diffraction intensities of the (111) plane and (311) plane obtained in the thickness direction on the rolled surface using the X-ray diffraction method are I ₍₁₁₁₎ and I ₍₃₁₁₎ , respectively, I ₍₁₁₁₎ The copper alloy sheet according to (1) or (2), wherein / I ₍₃₁₁₎ is 5.0 or less.
(4) The copper alloy plate according to any one of (1) to (3), characterized by containing 1.0 mass% or less of Sn.
(5) Any one of (1) to (4) containing 1.0% by mass or less of at least one of Ag, Fe, Co, Ni, Cr, Mn, Mg, Si, P and B A copper alloy plate according to any one of the above.
(6) An electronic component for high current using the copper alloy plate according to any one of (1) to (5).
(7) A heat dissipating electronic component using the copper alloy plate according to any one of (1) to (5).
(8) After hot rolling the ingot at a temperature of 800 to 1000 ° C. to a thickness of 3 to 30 mm, the cold rolling and the recrystallization annealing are repeated, and after the final cold rolling, the copper alloy sheet is subjected to strain relief annealing. Manufacturing process,
(A) In the recrystallization annealing before the final cold rolling, the furnace temperature is 350 to 800 ° C., the average crystal grain size of the copper alloy plate is adjusted to 2 to 50 μm,
(B) In the final cold rolling, the total working degree is 25 to 99%, the rolling work degree per pass is 20% or less,
(C) In the strain relief annealing, using a continuous annealing furnace, the furnace temperature is 300 to 700 ° C., the tension applied to the copper alloy sheet in the furnace is 1 to 5 MPa, and the copper alloy sheet is passed through, 0 .2% yield strength is reduced by 10-50 MPa,
The method for producing a copper alloy plate according to any one of (1) to (5).

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the copper alloy board which has high intensity | strength, high electroconductivity, and the outstanding stress relaxation characteristic, its manufacturing method, and an electronic component suitable for a large current use or a heat dissipation use. This copper alloy can be suitably used as a material for electronic parts such as terminals, connectors, switches, sockets, relays, bus bars, lead frames, heat sinks, etc., especially for electronic parts that carry a large current or a large amount of heat. It is useful as a material for electronic parts that dissipate the energy.

It is a figure explaining the measurement principle of a stress relaxation rate. It is a figure explaining the measurement principle of a stress relaxation rate.

The present invention will be described below.
(Characteristic)
In this invention, it aims at adjusting the electrical conductivity and 0.2% yield strength of a copper alloy board to 30% IACS or more and 350MPa or more, respectively. If the electrical conductivity is 30% IACS or more, heat generation during energization is reduced, and a reduction in contact force due to stress relaxation is reduced. In addition, if the 0.2% proof stress is 350 MPa or more, it can be said that the material has the strength necessary for a material for a component that conducts a large current or a material for a component that dissipates a large amount of heat.
Regarding stress relaxation characteristics, the stress relaxation rate when 80% stress of 0.2% proof stress is applied and held at 150 ° C. for 1000 hours is reduced to 50% or less, more preferably 40% or less, and even more preferably 30%. The goal is to do. The stress relaxation rate of a normal Cu—Zn alloy is about 70 to 80%, and by making this 50% or less, contact electricity accompanying a decrease in contact force even when a large current is applied after processing into a connector. Resistance does not easily increase, and creep deformation does not easily occur even if heat and external force are applied simultaneously after processing to a heat sink.
The copper alloy plate of the present invention having the above characteristics is suitable for use in high-current electronic components.

(Alloy component concentration)
The Zn concentration is 2 to 22% by mass, preferably 2 to 12% by mass. When Zn exceeds 22% by mass, it becomes difficult to obtain a conductivity of 30% IACS or more, and when Zn is less than 2%, it becomes difficult to obtain a 0.2% proof stress of 350 MPa or more.

1 mass% or less of Sn can be added to the Cu-Zn type alloy of this invention. Sn has the effect of promoting work hardening of the alloy during rolling and improving the strength of the alloy. Further, although not as much as Zr and Ti described above, Sn also has an effect of improving stress relaxation characteristics.
When Sn exceeds 1% by mass, the decrease in conductivity is increased. In order to acquire the effect of Sn addition, it is preferable to make the addition amount of Sn 0.001 mass% or more. A more preferable range of the Sn concentration is 0.1 to 0.6% by mass.
In addition, since it is difficult for Sn to form an oxide in molten copper, as long as it is added at a concentration of 1% or less, Sn addition does not deteriorate the manufacturability and quality of the alloy. Further, since Sn is stably dissolved in solid copper, the effect of Sn on the product characteristics is stably exhibited as long as it is added at a concentration of 1% or less.

  In order to improve strength and heat resistance, the Cu—Zn alloy of the present invention may contain one or more of Ag, Fe, Co, Ni, Cr, Mn, Mg, Si, P and B. it can. However, if the addition amount is too large, the electrical conductivity is lowered or the productivity is deteriorated, so the addition amount is 1.0% by mass or less, more preferably 0.1% by mass or less, more preferably, in total. It is limited to 0.05% by mass or less. Moreover, in order to acquire the effect by addition, it is preferable to make addition amount 0.001 mass% or more in total amount.

(Spring limit value)
When the spring limit value of the product is Kb (MPa) and the 0.2% proof stress is σ (MPa), the relationship is Kb ≧ (σ−100), more preferably the relationship Kb ≧ (σ−50). The stress relaxation property is improved by adjusting to. In the case of Kb <(σ-100), the stress relaxation rate exceeds 50%. The upper limit value of Kb is not particularly restricted, but normally it is rare that it exceeds σ.

(Crystal orientation of rolling surface)
By adjusting I ₍₁₁₁₎ / I ₍₃₁₁₎ to 5.0 or less, preferably 2.0 or less on the rolled surface of the product, the stress relaxation characteristics are improved. Here, I ₍₁₁₁₎ and I ₍₃₁₁₎ are diffraction integrated intensities of the (111) plane and the (311) plane obtained in the thickness direction using the X-ray diffraction method, respectively. When I ₍₁₁₁₎ / I ₍₃₁₁₎ exceeds 5.0, the stress relaxation rate exceeds 50%. Although the lower limit of _{I (111) / I (311} ) is not limited in terms of the stress relaxation characteristics _{improved, I (111) / I (} 311) typically takes a value of more than 0.01.

(Thickness)
The thickness of the product is preferably 0.1 to 2.0 mm. If the thickness is too small, the cross-sectional area of the current-carrying part will decrease and heat generation will increase during energization, making it unsuitable as a connector or other material that carries a large current. It is also unsuitable as a material. On the other hand, if the thickness is too thick, bending becomes difficult. From such a viewpoint, a more preferable thickness is 0.2 to 1.5 mm. When the thickness is in the above range, the bending workability can be improved while suppressing heat generation during energization.

(Use)
The copper alloy plate according to the embodiment of the present invention is suitably used for applications of electronic parts such as terminals, connectors, relays, switches, sockets, bus bars, lead frames, heat sinks, etc. used in electric / electronic devices, automobiles, etc. In particular, applications of high-current electronic components such as connectors and terminals for large currents used in electric vehicles, hybrid vehicles, etc., or uses of electronic components for heat dissipation such as liquid crystal frames used in smartphones and tablet PCs Useful for.

(Production method)
As a pure copper raw material, electrolytic copper or the like is dissolved, Zn and other alloy elements are added as required, and cast into an ingot having a thickness of about 30 to 300 mm. After this ingot is made into a plate having a thickness of about 3 to 30 mm by hot rolling at 800 to 1000 ° C., for example, cold rolling and recrystallization annealing are repeated, and finally finished to a predetermined product thickness by cold rolling. Apply strain relief annealing. The spring limit value after the final cold rolling is so low that it does not reach 100 MPa, but rises by subsequent strain relief annealing.

In the recrystallization annealing before the final cold rolling, the average crystal grain size of the copper alloy sheet is adjusted to 2 to 50 μm. If the average grain size is too small, it becomes difficult to adjust I ₍₁₁₁₎ / I ₍₃₁₁₎ to 5.0 or less. On the other hand, if the average crystal grain size is too large, it is difficult to adjust the 0.2% proof stress to 350 MPa or more.

  The recrystallization annealing before the final cold rolling is performed at a furnace temperature of 350 to 800 ° C., and a batch furnace or a continuous annealing furnace may be used. In a batch furnace, by appropriately adjusting the heating time in the range of 30 minutes to 30 hours at an in-furnace temperature of 350 to 600 ° C., and in a continuous annealing furnace, a range of 5 seconds to 10 minutes at an in-furnace temperature of 450 to 800 ° C. By appropriately adjusting the heating time, the average crystal grain size can be adjusted to 2 to 50 μm.

In the final cold rolling, the material is repeatedly passed between a pair of rolling rolls to finish the target plate thickness. The total workability of final cold rolling and the workability per pass are controlled.
The total workability R (%) is given by R = (t ₀ −t) / t ₀ × 100 (t ₀ : plate thickness before final cold rolling, t: plate thickness after final cold rolling). Further, the processing degree r (%) per pass is a sheet thickness reduction rate when the rolling roll passes once, and r = (T ₀ −T) / T ₀ × 100 (T ₀ : rolling roll) Thickness before passing, T: Thickness after passing the rolling roll).
The total processing degree R is 25 to 99%. If R is too small, it is difficult to adjust the 0.2% proof stress to 350 MPa or more. When R is too large, the edge of the rolled material may be broken.

The degree of processing r per pass is 20% or less. If r is too large increases _{I (111) / I (311} ), the path that r is more than 20% among all paths include even one I a _{(111) / I (311)} 5.0 It becomes difficult to adjust to the following.

  The strain relief annealing of the present invention is performed using a continuous annealing furnace. In the case of a batch furnace, the material is heated in a coiled state, so that the material undergoes plastic deformation during the heating, and the material is warped. Therefore, the batch furnace is not suitable for the strain relief annealing of the present invention.

In the continuous annealing furnace, the furnace temperature is set to 300 to 700 ° C., the heating time is appropriately adjusted in the range of 5 seconds to 10 minutes, and the 0.2% proof stress (σ) after the stress relief annealing is 0 before the stress relief annealing. Adjust to a value 10 to 50 MPa lower, preferably 15 to 45 MPa lower than 2% proof stress (σ ₀ ). Thereby, Kb which was low in the final cold rolling is sufficiently increased. If (σ ₀ −σ) is too small or too large, Kb does not rise sufficiently, and it becomes difficult to obtain the relationship of Kb ≧ (σ−100).

Further, the tension applied to the material in the continuous annealing furnace is adjusted to 1 to 5 MPa, more preferably 1 to 4 MPa. If the tension is too large, it becomes difficult to adjust I ₍₁₁₁₎ / I ₍₃₁₁₎ to 5.0 or less. Further, the increase in Kb tends to be insufficient. On the other hand, if the tension is too small, the material in the passing plate of the annealing furnace may come into contact with the furnace wall, and the surface or edge of the material may be damaged.

One aspect of the present invention is to improve stress relaxation characteristics by imparting a feature of Kb ≧ (σ−100) and a feature of I ₍₁₁₁₎ / I ₍₃₁₁₎ ≦ 5.0 to a Cu—Zn alloy. It is a feature, but if you organize and show the manufacturing conditions for that,
(1) For Kb ≧ σ−100,
a. In the strain relief annealing, (σ ₀ −σ) = 10 to 50 MPa is adjusted.
b. The furnace tension in the strain relief annealing is adjusted to 5 MPa or less.
(2) For I ₍₁₁₁₎ / I ₍₃₁₁₎ ≦ 5.0,
a. In the recrystallization annealing before the final cold rolling, the average crystal grain size is adjusted to 2 μm or more.
b. In the final cold rolling, the degree of processing per pass is adjusted to 20% or less.
c. The furnace tension in the strain relief annealing is adjusted to 5 MPa or less.

Examples of the present invention will be described below together with comparative examples, but these examples are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention.
After adding the alloy element to the molten copper, it was cast into an ingot having a thickness of 200 mm. The ingot was heated at 850 ° C. for 3 hours and formed into a plate having a thickness of 15 mm by hot rolling. After grinding and removing the oxide scale on the surface of the hot rolled plate with a grinder, annealing and cold rolling were repeated, and the product was finished to a predetermined product thickness by final cold rolling. Finally, strain relief annealing was performed using a continuous annealing furnace.

  The annealing before the final cold rolling (final recrystallization annealing) was performed using a batch furnace when the thickness during annealing exceeded 2 mm, and a continuous annealing furnace when the thickness was 2 mm or less. In the case of a batch furnace, the heating time was 5 hours, the furnace temperature was adjusted in the range of 300 to 700 ° C., and the crystal grain size after annealing was changed. In the case of a continuous annealing furnace, the furnace temperature was set to 700 ° C., and the heating time was appropriately adjusted between 1 second and 15 minutes to change the crystal grain size after annealing. In the measurement of the crystal grain size after annealing, a cross section perpendicular to the rolling direction was subjected to chemical corrosion after mirror polishing, and the average crystal grain size was determined by a cutting method (JIS H0501 (1999)).

In the final cold rolling, the total workability and the workability per pass were controlled. Moreover, the 0.2% yield strength of the material after final cold rolling was calculated | required.
In strain relief annealing using a continuous annealing furnace, the furnace temperature was 500 ° C., the heating time was adjusted between 1 second and 15 minutes, and the 0.2% proof stress after annealing was variously changed. In addition, various tensions were added to the material in the furnace. In some cases, strain relief annealing was not performed.
The following measurement was performed on the material in the process of manufacturing and the material after strain relief annealing.

(component)
The alloy element concentration of the material after strain relief annealing was analyzed by ICP-mass spectrometry.

(0.2% yield strength)
For the material after the final cold rolling and strain relief annealing, sample No. 13B specified in JIS Z2241 was taken so that the tensile direction was parallel to the rolling direction, and pulled in parallel with the rolling direction in accordance with JIS Z2241. Tests were performed to determine 0.2% yield strength.

(Spring limit value)
A strip-shaped test piece having a width of 10 mm and a length of 100 mm was taken from the material after strain relief annealing so that the longitudinal direction of the test piece was parallel to the rolling direction, and was subjected to a moment type test specified in JIS H3130. The spring limit value in the direction parallel to the rolling direction was measured.

(conductivity)
A test piece was taken from the material after strain relief annealing so that the longitudinal direction of the test piece was parallel to the rolling direction, and the conductivity at 20 ° C. was measured by a four-terminal method in accordance with JIS H0505.

(Crystal orientation)
The X-ray diffraction integrated intensity of the (111) plane and (311) plane was measured in the thickness direction with respect to the surface of the material after strain relief annealing. RINT 2500 manufactured by Rigaku Corporation was used as the X-ray diffractometer, and measurement was performed with a Cu tube bulb at a tube voltage of 25 kV and a tube current of 20 mA.

(Stress relaxation rate)
A strip-shaped test piece having a width of 10 mm and a length of 100 mm was collected from the material after strain relief annealing so that the longitudinal direction of the test piece was parallel to the rolling direction. As shown in FIG. 1, with the position of l = 50 mm as the working point, a deflection of y ₀ was given to the test piece, and a stress (s) corresponding to 80% of the 0.2% proof stress in the rolling direction was applied. y ₀ was determined by the following equation.
y ₀ = (2/3) · l ² · s / (E · t)
Here, E is the Young's modulus in the rolling direction, and t is the thickness of the sample. Unloading after heating at 150 ° C. for 1000 hours, and measuring the amount of permanent deformation (height) y as shown in FIG. 2, stress relaxation rate {[y (mm) / y ₀ (mm)] × 100 (%) } Was calculated.

Table 1 shows the evaluation results. Here, in the final cold rolling, a plurality of passes were performed, and the maximum value of the degree of processing of each pass is shown.
The Zn concentration is adjusted to 2 to 22%, the crystal grain size is adjusted to 2 to 50 μm in the recrystallization annealing before the final cold rolling, and the total workability is set to 25 to 99% in the final cold rolling. The copper according to the present invention, in which the workability per pass was adjusted to 20% or less, and in strain relief annealing, the material was passed through a continuous annealing furnace at a tension of 1 to 5 MPa to reduce the 0.2% proof stress by 10 to 50 MPa. In the alloy plate, a relationship of Kb ≧ (σ−100) and a relationship of I ₍₁₁₁₎ / I ₍₃₁₁₎ ≦ 5.0 are obtained, conductivity of 30% IACS or more, 0.2% proof stress of 350 MPa or more, A stress relaxation rate of 50% or less was achieved.

In Comparative Example 3, strain relief annealing was not performed, and the stress relaxation rate was extremely large.
In Comparative Examples 1 and 2, although strain relief annealing was performed, since the material tension in the furnace exceeded 5 MPa, I ₍₁₁₁₎ / I ₍₃₁₁₎ exceeded 5.0 and the comparatively high tension. 2 (σ−Kb) also exceeded 100. The stress relaxation rate of Comparative Examples 1 and 2 exceeded 50%.
In Comparative Examples 5 and 6, the amount of decrease in 0.2% proof stress during strain relief annealing was too small and too large, and (σ ₀ −σ) deviated from the range of 10 to 50 MPa. For this reason, (σ−Kb) exceeded 100 and the stress relaxation rate exceeded 50%.

In Comparative Example 4, since the degree of work per pass in the final cold rolling exceeded 20%, I ₍₁₁₁₎ / I ₍₃₁₁₎ exceeded 5.0 and the stress relaxation rate exceeded 50%.
In Comparative Example 11, the total work degree in the final cold rolling was less than 25%, so the 0.2% yield strength after strain relief annealing was less than 350 MPa.
In Comparative Example 7, since the crystal grain size after recrystallization annealing before the final cold rolling was less than 2 μm, I ₍₁₁₁₎ / I ₍₃₁₁₎ exceeded 5.0 and the stress relaxation rate exceeded 50%. It was.

In Comparative Example 8, since the crystal grain size after recrystallization annealing before the final cold rolling exceeded 50 μm, the 0.2% proof stress after strain relief annealing was less than 350 MPa.
In Comparative Example 9, since the Zn concentration was less than 2% by mass, the 0.2% proof stress after strain relief annealing was less than 350 MPa.
In Comparative Example 10, since the Zn concentration exceeded 22% by mass, the conductivity was less than 30% IACS.

Claims (8)

  It contains 2 to 22% by mass of Zn, the balance is made of copper and its inevitable impurities, has a conductivity of 30% IACS or more, a 0.2% proof stress of 350 MPa or more, and a 0.2% proof stress A copper alloy sheet characterized by having a stress relaxation rate of 50% or less after being applied at 80 ° C. and holding at 150 ° C. for 1000 hours.   The copper alloy sheet according to claim 1, wherein the relationship between the spring limit value Kb (MPa) and the 0.2% yield strength σ (MPa) is given by Kb ≧ (σ−100). When the integrated diffraction intensities of the (111) plane and (311) plane obtained in the thickness direction on the rolled surface using the X-ray diffraction method are I ₍₁₁₁₎ and I ₍₃₁₁₎ , respectively, I ₍₁₁₁₎ / I ₍ The copper alloy sheet according to claim 1 or 2, wherein ₃₁₁₎ is 5.0 or less.   The copper alloy sheet according to any one of claims 1 to 3, comprising 1.0 mass% or less of Sn.   5. One or more of Ag, Fe, Co, Ni, Cr, Mn, Mg, Si, P, and B are contained in an amount of 1.0% by mass or less. 5. Copper alloy plate.   The electronic component for high currents using the copper alloy plate of any one of Claims 1-5.   The electronic component for heat dissipation using the copper alloy plate of any one of Claims 1-5. In the process of manufacturing a copper alloy sheet, after ingot is hot-rolled at a temperature of 800 to 1000 ° C. to a thickness of 3 to 30 mm, cold rolling and recrystallization annealing are repeated, and after final cold rolling, strain relief annealing is performed. There,
(A) In the recrystallization annealing before the final cold rolling, the furnace temperature is 350 to 800 ° C., the average crystal grain size of the copper alloy plate is adjusted to 2 to 50 μm,
(B) In the final cold rolling, the total working degree is 25 to 99%, the rolling work degree per pass is 20% or less,
(C) In the strain relief annealing, using a continuous annealing furnace, the furnace temperature is 300 to 700 ° C., the tension applied to the copper alloy sheet in the furnace is 1 to 5 MPa, and the copper alloy sheet is passed through, 0 .2% yield strength is reduced by 10-50 MPa,
The method for producing a copper alloy plate according to any one of claims 1 to 5, wherein

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