KR100792653B1 - Copper alloy for electronic and electric machinery and tools, and manufacturing method thereof - Google Patents

Abstract

     (Problem) It is to provide a low-cost copper alloy which has both sufficient electrical conductivity and strength, and can cope with the miniaturization of electronic component parts.

     (Solution means) 2 to 12% by mass of Zn and 0.1 to 1.0% by mass of Sn, the relationship between the mass% concentration of Sn ([% Sn]) and the mass% concentration of Zn ([% Zn]),

0.5 ≤ [% Sn] + 0.16 [% Zn] ≤ 2.0

The grain shape and crystal orientation of the copper alloy, wherein the remainder is made of copper and its unavoidable impurities, and the S concentration is 30 mass ppm or less and the O concentration is 50 mass ppm or less. By adjusting to within an appropriate range, a copper alloy having a conductivity of 35% IACS or more and a tensile strength of 410 MPa or more and capable of 180-degree close bending of a bedway and a goodway can be obtained at a low price.

Description

Copper alloy for electrical and electronic equipment and its manufacturing method {COPPER ALLOY FOR ELECTRONIC AND ELECTRIC MACHINERY AND TOOLS, AND MANUFACTURING METHOD THEREOF}

1 is a schematic diagram of a bending test method.

2 is an invention example No. in which no elements other than Sn and Zn are added. 1 to 31 and Comparative Example No. It is a figure which shows the relationship between T and electrical conductivity using the data of 42-45.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy having both good strength, electrical conductivity and bending workability, and suitable for electric and electronic parts such as terminals, connectors, switches, and relays.

Inexpensive brass is used for various terminals, connectors, relays, switches, and the like of electrical and electronic equipments in applications where manufacturing price is important. Phosphor bronze is used for applications in which springability is important, and silver and silver are used in applications in which springability and corrosion resistance are important. These copper alloys are solid solution-reinforced alloys, and the strength and the spring property are improved by the action of the alloying elements, while the conductivity and the thermal conductivity are lowered.

On the other hand, in recent years, the amount of precipitation-reinforced copper alloys is increasing instead of the solid solution-reinforced alloys. A precipitation strengthening alloy is characterized by depositing an alloying element as fine compound particles in Cu matrix. When the alloying element precipitates, the strength increases, and at the same time, the electrical conductivity also increases. Therefore, in the precipitation strengthening alloy, higher conductivity can be obtained at the same strength with respect to the solid solution strengthening alloy. Examples of the precipitation-reinforced copper alloys include Cu-Ni-Si alloys, Cu-Be alloys, Cu-Ti alloys, and Cu-Zr alloys.

However, in the precipitation-reinforced alloy, a high temperature and a short time heat treatment (solvation treatment) for solidifying the alloying element in Cu once and a low temperature and a long time heat treatment (aging treatment) for the precipitation of the alloy element are necessary, and the manufacturing process Is complicated. In addition, since the alloying element contains active elements such as Si, Ti, Zr and Be, production of ingot quality is difficult. Therefore, the manufacturing price of a precipitation strengthening alloy is very expensive compared with the manufacturing price of a solid solution strengthening alloy.

In recent years, with the miniaturization of electronic component parts, terminals, connectors, switches, relays, and the like have been miniaturized, and the cross-sectional area of the energized portion of the copper alloy has been reduced. When the cross-sectional area of the energizing portion decreases, the amount of heat generated when the current flows increases. Use of a copper alloy having a higher electrical conductivity can suppress an increase in this calorific value.

In the case of using a conventional solid solution strengthened copper alloy, if a copper alloy having a high electrical conductivity is selected, the strength thereof is low, resulting in problems such as a lack of contact force at the electrical contact. On the other hand, when a precipitation strengthening type alloy is used, although electrical conductivity can be improved without reducing intensity | strength, price will increase. The market demand for copper alloy prices is strict, making price increases unacceptable.

In view of the above, the development of an inexpensive copper alloy having sufficient electrical conductivity and strength has been studied by improving the solid solution type alloy. Cu-Zn alloys represented by brass are alloys that are easy to manufacture and that Zn is also inexpensive, and can be produced at a particularly low price. It is attempted to improve the characteristic of this Cu-Zn alloy and to expand the use as an electronic component raw material. For example, the following patent document 1, patent document 2, and patent document 3 disclose the copper alloy which added Sn to Cu-Zn alloy.

(Patent Document 1) Japanese Unexamined Patent Publication No. 1-162737

(Patent Document 2) Japanese Unexamined Patent Application Publication No. 2-170954

(Patent Document 3) Japanese Unexamined Patent Publication No. 7-258777

However, the Cu-Zn-Sn-based alloy disclosed in these documents cannot be said to have good electrical conductivity, strength, and bendability, and was not capable of miniaturizing electronic device components.

An object of the present invention is to provide a low-cost copper alloy which has both necessary sufficient conductivity and strength and can cope with miniaturization of electronic component parts.

      MEANS TO SOLVE THE PROBLEM The present inventors obtained the copper alloy which has sufficient electric conductivity, strength, and bending workability by adjusting Zn amount of Cu-Zn alloy, adding a small amount of Sn, and adjusting a metal structure.

That is, the present invention,

(1) 2-12 mass% Zn and 0.1-1.0 mass% Sn, and the relationship between the mass% concentration ([% Sn]) of Sn and the mass% concentration ([% Zn]) of Zn is The balance is made of copper and its unavoidable impurities, S concentration is 30 mass ppm or less, O concentration is 50 mass ppm or less, and has conductivity of 35% IACS or more and tensile strength of 410MPa or more. Copper alloy for electrical and electronic equipment, characterized in that the 180-degree close bending of the bed way (the direction in which the bending axis is parallel to the rolling direction) and the good way (the direction in which the bending axis is perpendicular to the rolling direction)

  0.5 ≤ [% Sn] + 0.16 [% Zn] ≤ 2.0

(2) Said (1) characterized by containing at least 1 sort (s) of Ni, Mg, Fe, P, Mn, Co, Be, Ti, Cr, Zr, Al, and Ag in 0.005-0.5 mass% in total. Copper Alloy for Electrical and Electronic Devices

(3) The copper alloy for electric and electronic equipment of (1) and (2) above, wherein the number of inclusions having a length exceeding 50 µm in the cross section parallel to the rolling direction and the thickness direction is 0.5 pieces / mm 2 or less.

(4) In the metal structure of the cross section parallel to a rolling surface, the crystal grain which comprises a metal structure has the shape extended in the rolling direction, and the average particle diameter of the direction orthogonal to the rolling direction of a crystal grain is a, and the rolling direction. When b is the average particle diameter in the parallel direction,

    a = 1.0-10.0 μm, preferably 1.0-5.0 μm

    b / a = 1.2 to 2.5

Copper alloy for electric and electronic equipment of said (1)-(3) characterized by having a dimension to become

(5) X-ray diffraction intensities from the (200) plane and the (220) plane in the rolled surface are set to I ₍₂₀₀₎ and I ₍₂₂₀₎ , _respectively , and (200) plane in the same powder. And X-ray diffraction intensities from the (220) plane, I _{0 (200)} and I _{0 (220)} , respectively.

0.2 ≤ I ₍₂₀₀₎ / I _{0 (200)} ≤ 1.0

2.0 ≤ I ₍₂₂₀₎ / I _{0 (220)} ≤ 5.0

Copper alloy for electric and electronic equipment of said (1)-(4) characterized by the above-mentioned

(6) The method for producing a copper alloy for electric and electronic equipment according to (1) to (5), wherein the following steps are performed sequentially.

    A. Intermediate recrystallization annealing to finish the crystal grain size to 1 ~ 10 ㎛

    B. Medium cold rolling with workability 35 ~ 90%

    C. Final recrystallization annealing to finish crystal grain size of 1 to 10 mu m, preferably 1 to 5 mu m

    D. Cold finish finishing 15 ~ 60%

To provide.

       The characteristics which the present invention deems necessary are as follows.

(A) Conductivity: 35% IACS or more. This conductivity is comparable to that of the Cu-Ni-Si-based alloy (Colson alloy), which is a precipitation strengthening alloy. In addition, the electrical conductivity of brass (C2600) is 28% IACS, and the phosphorous copper (C5210) has 13% IACS.

(B) Tensile strength: 410 MPa or more. This tensile strength corresponds to the tensile strength of quality H of brass (C2600) prescribed by JIS Standard (JIS H3100).

(C) Bending workability: 180 degree close bending of the good way and the bed way is possible. If no cracking or large surface roughness occurs in this bending test, the most rigorous level of bending performed on the connector is possible.

    In other words, the copper alloy provided by the present invention has the strength of brass, the conductivity of Kohlson alloy, the bending workability equal to or higher than that of brass or Kohlson alloy, and is said to be a copper alloy suitable as a raw material for electronic equipment parts miniaturized. Can be.

Among conventional Cu-Zn-Sn alloys, there was no alloy that satisfies all of the above (A) (B) (C). For example, in the alloy disclosed in Patent Document 3, although (A) and (B) are satisfied, structure control (optimization of inclusion distribution, grain shape, crystal orientation, etc.) necessary for achieving (C) Since it is not done, the bending workability is the level of 90 degree W bending (where R is a bending radius and t is a sample plate thickness) of R / t = 0.8.

  Here, the outline of the two types of bending test methods is shown in FIG.

 In this invention, in order to acquire the said characteristic, the component, structure, and manufacturing method of the alloy of this invention are limited as follows.

(1) Zn and Sn concentration

 The copper alloy of this invention uses Zn and Sn as a basic component, and produces | generates a mechanical characteristic by action of both elements. The ranges of Zn concentration and Sn concentration are 2-12 mass% and 0.1-1.0 mass%, respectively. If Zn is less than 2%, good manufacturability characteristic of the Cu-Zn alloy is lost. If Zn exceeds 12%, the desired conductivity cannot be obtained even if the Sn concentration is adjusted. It is preferable to make Zn into 7 mass% or less when an electrical conductivity is important as a product characteristic, and to make Zn more than 7 mass% when emphasis is given to strength.

Sn has the effect | action which accelerates work hardening at the time of rolling, and when Sn is less than 0.1%, strength is insufficient. On the other hand, when Sn exceeds 1.0%, the manufacturability of an alloy will fall.

 The total concentration T of Sn and Zn is adjusted as follows.

  0.5 ≤ T ≤ 2.0

  T = [% Sn] + 0.16 [% Zn]

 Here, [% Sn] and [% Zn] are the mass% concentrations of Sn and Zn, respectively. When T is 2.0 or less, a conductivity of 35% IACS or more can be obtained. When T is 0.5 or more, a tensile strength of 410 MPa or more can be obtained by appropriately adjusting the metal structure. There, T is prescribed | regulated to 0.5-2.0. The more preferable range of T is 1.0 to 1.7, and by adjusting in this range, the conductivity of 35% IACS or more and the tensile strength of 410 MPa or more can be more stably obtained.

(2) Ni, Mg, Fe, P, Mn, Co, Be, Ti, Cr, Zr, Al, Ag

 In the alloy of the present invention, at least one of Ni, Mg, Fe, P, Mn, Co, Be, Ti, Cr, Zr, Al, and Ag is used for the purpose of improving the strength, heat resistance, stress relaxation resistance, etc. of the alloy. It can add 0.005-0.5 mass% in total. However, addition of an alloying element causes a decrease in electrical conductivity, a decrease in manufacturability, an increase in raw material price, and the like.

 If the total amount of the above elements is less than 0.005% by mass, the effect of improving the characteristics is not expressed. On the other hand, when the total amount of the said element exceeds 0.5 mass%, electrical conductivity fall will become remarkable. There, the total amount is prescribed | regulated as 0.005-0.5 mass%.

(3) inclusion count, S concentration, O concentration

 The number of inclusions exceeding 50 micrometers in length observed in the cross section parallel to a rolling direction and parallel to a thickness direction is regulated to 0.5 piece / mm <2> or less. When inclusions exceed 0.5 piece / mm <2>, bending workability will fall remarkably and 180 degree close bending will become impossible.

 In order to adjust an inclusion to the said range, S and O concentration are prescribed | regulated to 30 mass ppm or less and 50 mass ppm or less, respectively. If the S or O concentration exceeds this range, the inclusions exceed 0.5 pieces / mm 2.

(4) grain shape

 When the metal structure of the cross section parallel to the rolling surface of the alloy of this invention is observed, the crystal grain of the shape extended in the rolling direction is observed. A value and b / a value correlate with the strength and bending workability of the alloy when a mean particle diameter in a direction orthogonal to the rolling direction of this crystal grain is a and b a mean particle diameter in a direction parallel to the rolling direction. Therefore, the properties of the alloy can be adjusted using these as parameters.

 When a falls below 1 micrometer, bending workability will fall and 180 degree close bending will become impossible. When a exceeds 10 micrometers, intensity | strength falls and it becomes difficult to obtain tensile strength of 410 Mpa or more, and when surface bending is performed, big surface roughness arises. There, a is prescribed | regulated to 1-10 micrometers, More preferably, it is 1-5 micrometers.

 When b / a exceeds 2.5, bending workability will fall and 180 degree close bending will become impossible. When b / a is less than 1.2, the strength decreases, and it becomes difficult to obtain a tensile strength of 410 MPa or more. There, b / a is prescribed | regulated as 1.2-2.5.

 In addition, in the case where the rolled structure is left in the final annealing without completely recrystallization, when the workability of the finish cold rolling is extremely high, deformation of the crystal grains becomes remarkable, and measurement of a and b / a becomes difficult. Bending workability of the alloy having a structure is very bad, 180-degree close bending is impossible.

(5) crystal orientation of the rolled surface

 By performing X-ray diffraction on the rolled surface of the copper alloy, the degree of integration of the (200), (220), (111), and (311) planes on the rolled surface can be obtained. In the case of the alloy of the present invention, the degree of integration of the (200) face and the (220) face has a correlation with the strength and bending workability of the alloy. Therefore, the characteristics of the alloy can be adjusted using these as parameters.

X-ray diffraction intensities from the (200) plane and the (220) plane on the rolled surface of the alloy are set to I ₍₂₀₀₎ and I ₍₂₂₀₎ , _respectively , and the (200) plane and (220) plane in the same powder. X-ray diffraction intensities are set to I _{0 (200)} and I _{0 (220} ), respectively, and the integration degree of each surface is evaluated by the ratio of I and I ₀ (I / I ₀ ). Here, the copper powder is used as a standard sample of random orientation, and by dividing the diffraction intensity (I) of the sample by the diffraction intensity (I ₀ ) of the same powder, You can get the value.

When I ₍₂₀₀₎ / I _{0 (200)} exceeds 1.0, the surface roughness of the bent surface becomes large when 180 degrees of close bending of the goodway is performed. On the other hand, if it is less than 0.2, the surface roughness of a bending surface will become large at the time of 180 degree close bending of a bedway. Therein, I ₍₂₀₀₎ / I _{0 (200)} is defined as 0.2 to 1.0.

If I ₍₂₂₀₎ / I _{0 (220)} is less than 2.0, the strength decreases, and it becomes difficult to obtain a tensile strength of 410 MPa or more. On the other hand, when it exceeds 5.0, bending workability will fall and 180 degree close bending will become impossible. There, I ₍₂₂₀₎ / I0 ₍₂₂₀₎ is defined as 2.0-5.0.

(6) manufacturing method

 The alloy of this invention performs the following process one by one, and finishes it with the raw material for electrical and electronic equipment.

(A) Intermediate recrystallization annealing: The crystal grain size is adjusted to 1 to 10 mu m.

(B) Medium cold rolling: Workability 35 to 90%.

(C) Final recrystallization annealing: The crystal grain size is adjusted to 1 to 10 mu m, preferably 1 to 5 mu m.

(D) Finish cold rolling: Workability 15 to 60%.

 Here, the workability R is defined by the following equation.

R = (t ₀ -t) / t ₀ (t ₀ : thickness before rolling, t: thickness after rolling)

When the workability of finish cold rolling becomes less than 15%, b / a is less than 1.2, and I ₍₂₂₀₎ / I _{0 (220)} is less than 2.0. On the other hand, when the workability of finish cold rolling exceeds 60%, b / a will exceed 2.5 and I ₍₂₂₀₎ / I0 ₍₂₂₀₎ will exceed 5.0. There, the workability of finish cold rolling is prescribed | regulated to 15 to 60%.

 If the crystal grain size in the final annealing is less than 1 µm, a is less than 1 µm. On the other hand, when the crystal grain size in final annealing exceeds 10 m, a exceeds 10 m. There, the crystal grain size in final annealing is defined to be 1 to 10 m, preferably 1 to 5 m.

When the workability of the intermediate cold rolling is less than 35%, I ₍₂₀₀₎ / I _{0 (200)} is less than 0.2. On the other hand, when the workability of the intermediate cold rolling exceeds 90%, I ₍₂₀₀₎ / I _{0 (200)} exceeds 1.0. There, the workability of intermediate cold rolling is prescribed | regulated as 35 to 90%.

If the grain size in the intermediate annealing is less than 1 µm, I ₍₂₀₀₎ / I _{0 (200)} exceeds 1.0. On the other hand, when the grain size in the intermediate annealing exceeds 10 µm, I ₍₂₀₀₎ / I _{0 (200)} is less than 0.2. There, the grain size in the intermediate annealing is defined to be 1 to 10 m.

Moreover, even after finishing cold rolling, even if annealing annealing is performed for the purpose of improving a spring limit value, stress corrosion cracking sensitivity, stress relaxation resistance, etc., the said of this invention The effect is the same. Moreover, even if plating of reflow Sn (tin) etc. is performed on the surface after finish cold rolling, the said effect of this invention will be acquired similarly if the thickness of a plating layer is within 5 micrometers.

(Example)

A high frequency induction furnace was used to melt 2 kg of electric copper in a graphite crucible having an inner diameter of 60 mm and a depth of 200 mm. After the molten metal surface was covered with charcoal pieces, Zn and Sn were added. Moreover, CuS was added as needed in order to adjust S concentration, and CuO was added as needed in order to adjust O concentration. After adjusting the molten metal temperature to 1200 degreeC, molten metal was inject | poured into the metal mold | die, the ingot of width 60mm and thickness 30mm was manufactured, and it processed to the thickness 0.3mm using the following process as a standard process.

(Process 1) After heating at 850 degreeC for 3 hours, it hot-rolls (hot rolled) to thickness 8mm.

(Step 2) The oxidation scale on the surface of the hot rolled sheet is ground and removed with a grinder.

(Step 3) Cold rolling (small rolling) to a plate thickness of 1.5 mm.

(Step 4) As recrystallization annealing (intermediate annealing), heating is performed at 400 ° C. for 30 minutes in the air, and the crystal grain diameter is adjusted to about 3 μm.

(Step 5) Pickling with a 10% by mass sulfuric acid-1% by mass hydrogen peroxide solution and mechanical polishing with # 1200 emery are carried out sequentially to remove the surface oxide film produced by the annealing.

(Process 6) By cold rolling (medium rolling), it rolls to 71% of workability to 0.43mm in thickness.

(Step 7) As recrystallization annealing (final annealing), heating is carried out at 400 ° C. for 30 minutes in the air, and the crystal grain diameter is adjusted to about 3 μm.

(Step 8) Pickling with a 10% by mass sulfuric acid-1% by mass hydrogen peroxide solution and mechanical polishing with # 1200 emery are carried out sequentially to remove the surface oxide film produced by the annealing.

(Step 9) Cold rolling (finishing rolling) is carried out to a workability of 30% to 0.3 mm.

 The following evaluation was performed about the obtained sample.

Measurement of inclusions

A cross section parallel to the rolling direction and the thickness direction was polished to mirror surface by mechanical polishing, and observed with a magnification of 400 times using an optical microscope, and the number of inclusions having a length (width in the rolling direction) of 50 µm or more. Measured. Regarding the inclusions (입자 -based inclusions) composed of particles connected in the rolling direction, the particle group distributed at intervals of 10 μm or less was regarded as one inclusion. The measurement of the inclusion was performed for an area of 100 mm 2, and the number of the included inclusions was converted into the number per 1 mm 2.

Grain shape

 The structure of the cross section parallel to the rolling surface was observed about the sample of intermediate | middle annealing completion, final annealing completion, and finish rolling completion.

 After the rolled surface was polished to mirror surface by mechanical polishing and electropolishing, a grain boundary appeared by etching, and the structure | photography photograph was taken. As etching liquid, the aqueous solution which mixed the ammonia water and the hydrogen peroxide solution was used, and the optical microscope and the scanning electron microscope were used suitably for the image | photograph of a tissue photograph. On the other hand, when the crystal grain size is small and it is difficult to determine the grain boundary by chemical etching, an azimuth map image is photographed by the Electron Backscattering Pattern (EVS) method using a mirror sample of electropolishing finish. The crystal shape was measured.

On the structure, the straight line was drawn in the direction orthogonal to the rolling direction, and the number of crystal grains cut | disconnected by the straight line was calculated | required. And the value which divided the length of the straight line by this crystal grain number was made into a. Similarly, the straight line was drawn in the direction parallel to the rolling direction, the number of crystal grains cut | disconnected by the straight line was calculated | required, and the value which divided the length of the straight line by this number of crystal grains was made into b.

 In the intermediate annealing completion and final annealing completion samples, the value of (a + b) / 2 was calculated | required and this was made into the crystal grain size of annealing completion. About the finish rolling completed sample, the value of b / a was calculated | required.

X-ray diffraction intensity

 Using the Co., Ltd. RINT2500 made by Rigaku Corporation as an X-ray diffraction apparatus, the integrated intensity | strength of the (200) plane and (220) plane was measured in the rolling surface of a sample. In addition, the same measurement was performed about the copper powder sample of 325 mesh.

Conductivity

 Based on JIS H 0505, it measured by the 4-probe method.

The tensile strength

 JIS 13B test piece was produced using the press machine so that the tension direction may become parallel to a rolling direction. The tensile test of this test piece was done according to JIS Z 2241, and the tensile strength was calculated | required.

Bending workability

 Using a 10 mm wide sample, adheres 180 degrees to the good way (direction in which the bending axis is orthogonal to the rolling direction) and bedway (direction in which the bending axis is parallel to the rolling direction) based on JIS Z 2248. A bending test was done. About the sample after bending, the presence or absence of a crack and the magnitude | size of surface roughness were observed in the surface and cross section of a bending part.

 (Circle) and the case where a crack generate | occur | produces (circle) and the case where a crack generate | occur | produced the case where a crack did not generate | occur | produce and a surface roughness was small, but a surface roughness was large.

 In addition to the 180-degree close bending test, the 90-degree W bending test of R = 0.24 mm (R / t = 0.8) was also performed based on JIS H 3110. , Goodway, Bedway, the evaluation result of ○ was obtained.

Example 1

The influence of Sn and Zn concentration on the conductivity and the tensile strength will be described. Samples having a thickness of 0.3 mm having Sn and Zn concentrations in Table 1 were prepared by the above standard process. The S concentrations of these samples were adjusted in the range of 10 to 15 mass ppm, and the O concentration was adjusted in the range of 20 to 30 mass ppm. It was. Moreover, the number of inclusions 50 micrometers in length or more was 0.1 piece / mm <2> or less. In addition, a is 1.4 is approximately 3 ㎛ _{degree, b / a, I (200} ) / I 0 (200) is in a range of _{0.4~0.6, I (220) / I} 0 (220) was in the range of 4.0 to 4.5 _is . Moreover, in all the alloys, the result of the 180-degree close bending test of the goodway and the bedway was (circle).

Table 1 shows the measured data of electrical conductivity and tensile strength. Sn and Zn concentrations,

  [% Zn] = 2-12, [% Sn] = 0.1-1.0

   0.5 ≤ T ≤ 2.0

   T = [% Sn] + 0.16 [% Zn]

In Inventive Examples Nos. 1 to 41 adjusted to the above range, target electrical conductivity of 35% IACS or more and tensile strength of 410 MPa or more are obtained.

 Inventive example No. 1-4 and comparative example No. 42,43 made Zn 8% and changed Sn density | concentration. As Sn increased, the conductivity decreased and the tensile strength increased. The tensile strength of No. 42 with less than 0.1% of Sn was less than 410 MPa. In No. 43, T exceeded 2 and the electrical conductivity fell below 35% IACS.

 Inventive example No. 2, 5-10, and comparative example No. 45 made Sn into 0.3%, and changed Zn density | concentration. As Zn increased, the conductivity decreased and the tensile strength increased. In No. 45 where Zn exceeded 12%, T exceeded 2 and the electrical conductivity fell below 35% IACS.

No. T becomes less than 0.5 At 44, the tensile strength was less than 410 MPa.

2 shows invention examples Nos. 1 to 31 and Comparative Examples No. 1 to which elements other than Sn and Zn were not added. The relationship between T and electrical conductivity is shown using the data of 42-45. It can be seen that there is a good correlation between T and conductivity.

Example 2

The influence of S, O concentration, and the number of inclusions on bending workability is demonstrated. Cu-Zn-Sn alloy ingots having different S and O shown in Table 2 were produced by the above method. However, when producing an ingot of 5 ppm or less in S concentration, desulfurization treatment was performed by adding sodium carbonate. In addition, when the ingot having an O concentration of 5 ppm or less was prepared, the raw material was dissolved in an argon stream. These ingots were processed to a thickness of 0.3 mm in the above standard process. A of these samples is about 3 μm, b / a is about 1.4, and I ₍₂₀₀₎ / I _{0 (200)} is in the range of 0.4 to 0.6, I _{( 220)} / I _{0 (220)} ranged from 4.0 to 4.5.

Inventive example No. 1-15 S is 30 mass ppm or less, O is 50 mass ppm or less, and the number of inclusions of 50 micrometers or more in length is 0.5 piece / mm <2> or less. In these samples, in the 180-degree close bending test, cracks did not occur in both the Good Way and the Bad Way, and the surface roughness was small.

 Invention Examples No. 1 to 5 and Comparative Examples No. 16 and 17 change O concentration to 25 to 30 mass ppm with respect to 8% Zn-0.3% Sn alloy. In No. 16 and 17 in which S exceeded 30 mass ppm, the number of inclusions exceeded 0.5 pieces / mm 2, and cracking occurred due to the 180 degree close bending.

 Inventive example No. 3, 6-10, and comparative example No. 18 make S into 12-15 mass ppm with respect to 8% Zn-0.3% Sn alloy, and change O concentration. In No. 18 in which O exceeded 50 mass ppm, the number of inclusions exceeded 0.5 pieces / mm 2, and cracks occurred at 180 degree close bending.

Example 3

 The influence of the grain shape, the crystal orientation of the rolled surface, and the manufacturing method on the tensile strength and the bending workability will be described. The Cu-Zn-Sn alloy ingot of Table 3 was produced by the above method, and processed to 0.3 mm in thickness. In this processing, the thickness at the completion of the small rolling (step 3) and the intermediate rolling (step 6) was changed with respect to the standard step. In the recrystallization annealing (step 4) and the final annealing (step 7), the heating time was set to 30 minutes and the heating temperature was changed.

Nos. 1 to 8 in Table 3 change the finish rolling workability by changing the plate thickness at the time of intermediate rolling completion. In addition, these intermediate rolling work drawing is in the scope of the present invention. As finish-rolling workability increases, b / a becomes large, I ₍₂₂₀₎ / I _{0 (220)} is high, and I ₍₂₀₀₎ / I _{0 (200)} is low.

In No. 1 having a finish rolling workability of less than 15%, b / a was less than 1.2, and I ₍₂₂₀₎ / I _{0 (220)} was less than 2.0. The tensile strength of No. 1 was less than 410 MPa.

Nos. 7 and 8 have a finish rolling workability exceeding 60%. In No. 7, b / a exceeded 2.5. In No. 8, the deformation of crystal grains was large, and measurement of a and b / a was impossible, and I ₍₂₂₀₎ / I _{0 (220)} exceeded 5.0. In close contact bending at 180 degrees, cracks occurred in the bedway in No. 7 and cracks occurred in both the good way and the bedway in No. 8.

 Nos. 9 to 15 in Table 3 change the crystal grain diameter of final annealing completion by changing the final annealing temperature. As a crystal grain size of final annealing completion increases, a increases.

In No. 9 in which the crystal grain size of the final annealing completion exceeded 10 µm, a exceeded 10 µm. The tensile strength of No. 9 was less than 410 MPa, and large surface roughness occurred by the close bending of 180 degrees. On the other hand, for No. 10 in which the crystal grain size of the final annealing completion was adjusted to 7.8 µm and a became 7.3 µm, the surface roughness of the 180 degree close bending was slightly larger than that of No. 11 to 13, but there was no practical problem. It was judged by the level (○). However, when the appearance of bending is particularly important, it can be said that it is preferable to adjust the crystal grain size of the final annealing completion to 5 µm or less and to make a to 5 µm or less.

In No. 14 whose crystal grain size of final annealing completion was less than 1 µm, a was less than 1 µm. In No. 14, the crack generate | occur | produced in the 180 degree close bending of the bedway.

 In No. 15, in the final annealing completion, an uncrystallized recrystallization unit (rolled structure) remained, and a and b / a could not be measured. In No. 15, the crack occurred in the goodway and the bedway at 180 degree close bending.

No. 16-20 of Table 3 changed the intermediate rolling workability by changing the plate | board thickness of the small rolling completion.

As the intermediate rolling workability increases, I ₍₂₀₀₎ / I _{0 (200)} increases, and I ₍₂₂₀₎ / I _{0 (220)} decreases slightly.

In No. 16 of which the intermediate rolling workability is less than 15%, I ₍₂₀₀₎ / I _{0 (200)} is less than 0.2. In No. 16, the big surface roughness generate | occur | produced in the 180 degree close bending of the bedway.

In No. 20 in which the intermediate rolling workability exceeds 90%, I ₍₂₀₀₎ / I _{0 (200)} exceeds 1.0. In No. 20, the big surface roughness generate | occur | produced in the 180 degree close bending of a goodway.

Nos. 21 to 25 in Table 3 change the grain size of the intermediate annealing completion by changing the intermediate annealing temperature. As the grain size of the intermediate annealing completion is smaller, I ₍₂₀₀₎ / I _{0 (200)} is higher and I ₍₂₂₀₎ / I _{0 (220)} is slightly lower.

In No. 21 in which the crystal grain size of the intermediate annealing completion exceeded 10 µm, I ₍₂₀₀₎ / I _{0 (200)} is less than 0.2. In No. 21, the big surface roughness generate | occur | produced in the 180 degree close bending of the bedway.

No. 25 indicates that an unrecrystallized portion (rolled structure) remained in the intermediate annealing and the average grain size could not be adjusted to 1 µm or more, and I ₍₂₀₀₎ / I _{0 (200)} exceeded 1.0. In No. 25, the big surface roughness generate | occur | produced in the 180 degree close bending of a goodway.

It is possible to produce a copper alloy that can be miniaturized in electronic device parts with sufficient conductivity and strength as required, at a low price.

Claims (8)

Zn of 2-12% by mass and 0.1-1.0% by mass of Sn, and the relation between the mass% concentration of Sn ([% Sn]) and the mass% concentration of Zn ([% Zn]) in the range of the following formula The balance is made of copper and its unavoidable impurities, and the S concentration is 30 mass ppm or less and the O concentration is 50 mass ppm or less in the unavoidable impurities and observed in the cross section parallel to the rolling direction and the thickness direction. The number of inclusions having a length exceeding 50 μm is 0.5 pieces / mm 2 or less, and has a conductivity of 35% IACS or more and a tensile strength of 410 MPa or more, and a bed way (direction in which the bending axis is parallel to the rolling direction). And a copper alloy for an electric and electronic device, characterized in that a 180 degree close bending process of a good way (a direction in which the bending axis is orthogonal to the rolling direction) is possible.   0.5 ≤ [% Sn] + 0.16 [% Zn] ≤ 2.0 The method of claim 1, wherein at least one of Ni, Mg, Fe, P, Mn, Co, Be, Ti, Cr, Zr, Al, and Ag is contained in a range of 0.005 to 0.5 mass% in total. Copper alloy for electronic devices. delete The metal structure of the cross section parallel to the rolling surface, When the crystal grain which comprises a metal structure has the shape extended in the rolling direction, and the average particle diameter of the direction orthogonal to the rolling direction of a crystal grain is a and the average particle diameter of the direction parallel to a rolling direction is b,  a = 1.0-10.0 μm  b / a = 1.2 to 2.5 Copper alloy for electrical and electronic equipment, characterized by having a dimension of. The copper alloy for electrical and electronic equipment according to claim 4, wherein a = 1.0 to 5.0 µm. The X-ray diffraction intensities from the (200) plane and the (220) plane in the rolled surface are referred to as I ₍₂₀₀₎ and I ₍₂₂₀₎ , respectively _, and _{(200) in the} same powder. The X-ray diffraction intensities from the plane and (220) plane are I _{0 (200)} and I _{0 (220)} , _respectively . When you do, 0.2 ≤ I ₍₂₀₀₎ / I _{0 (200)} ≤ 1.0 2.0 ≤ I ₍₂₂₀₎ / I _{0 (220)} ≤ 5.0 Copper alloy for electrical and electronic equipment, characterized in that the.       The following process is performed sequentially, The manufacturing method of the copper alloy for electrical and electronic equipment of Claim 1 or 2 characterized by the above-mentioned. A. Intermediate recrystallization annealing to finish the crystal grain size to 1 ~ 10 ㎛ B. Medium cold rolling with a workability of 35 to 90% C. Final recrystallization annealing to finish the crystal grain size to 1 ~ 10 ㎛ D. Cold drawn finish 15 ~ 60% finish   8. The method for producing a copper alloy for electrical and electronic equipment according to claim 7, wherein the crystal grain size of the step C is 1 to 5 mu m.

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