JP5916418B2 - Copper alloy sheet and manufacturing method thereof - Google Patents

Description

  The present invention relates to a copper alloy plate material applied to lead frames, connectors, terminal materials, relays, switches, sockets, and the like for electrical and electronic equipment, and a method for manufacturing the same.

  Characteristic items required for copper alloy sheets used in automotive parts and lead frames, connectors, terminal materials, relays, switches, sockets, etc. for electric components, electrical conductivity, yield strength, Has tensile strength, bending workability, stress relaxation resistance, and fatigue characteristics. In recent years, with the miniaturization, weight reduction, high functionality, high density mounting, and high temperature of use environment of electric / electronic devices, the required characteristic level has been increased.

  In recent years, automotive components such as lead frames and connectors, as well as electrical and electronic equipment components, have tended to be highly integrated, downsized, and lightened. At the same time, copper and copper alloy plate materials have become thinner. There is a tendency. For this reason, the strength level required for the material is more severe. In particular, automobile connectors are used in an environment where severe vibrations are repeatedly applied, so the material has a further improved property that is less susceptible to fatigue failure, that is, higher fatigue strength (excellent fatigue properties). It is required to have.

  In addition, materials used for components such as connectors, lead frames, relays, and switches that make up in-vehicle components and electrical / electronic components have high strength to withstand the stress applied during assembly and operation of electrical / electronic devices. Is required. In addition, since electric / electronic parts are generally formed by bending, further improvement in bending workability is also required.

  As a strengthening method for increasing the strength corresponding to these high requirements, there is precipitation strengthening in which a fine second phase is precipitated in the material. This strengthening method has the merit of improving the conductivity at the same time in addition to increasing the strength. However, with the recent miniaturization of parts used in electronic devices and automobiles, the copper alloy materials used are required to be able to bend a higher-strength material with a smaller radius as described above. Therefore, there is a strong demand for a copper alloy sheet material having excellent bending workability. However, it was not possible to obtain a material with sufficient bending workability by precipitation strengthening.

In addition, in the conventional Cu-Ni-Si system, in order to obtain a high strength, the rolling process rate was increased and a large work hardening was obtained. However, this method conversely deteriorated the bending workability, resulting in a high strength. And good bending workability could not be achieved at the same time.
Furthermore, it is not preferable that there is a difference in properties between the rolling direction and the vertical direction of rolling even in a plate material having high strength, high spring property and good bending workability, and it is important to show good properties in any direction. . In particular, when used as an ultra-small terminal, a pin-type and fine processing is performed with a narrow width. In such a case, it is important to show good characteristics in any direction.

Several proposals have been made to solve the demand for improvement in bending workability by controlling the crystal orientation. For example, the following disclosures have been made on Cu—Ni—Si based copper alloys. Patent Document 1 discloses that in a Cu—Ni—Si based copper alloy, the crystal grain size and the crystal orientation such that the X-ray diffraction intensity I from the {311}, {220}, and {200} planes satisfies a certain condition are satisfied. In some cases, it is disclosed that bending workability is excellent. Patent Document 2 discloses that in a Cu—Ni—Si-based copper alloy, bending workability is excellent when the crystal orientation satisfies the condition that the X-ray diffraction intensity from the {200} plane and the {220} plane is satisfied. It is disclosed. Patent Document 3 discloses that in a Cu—Ni—Si based copper alloy, bending workability is excellent by controlling the ratio of the Cube orientation {001} <100>.
In Patent Document 4, the crystal structure in a distorted state due to strong cold working is recrystallized to change to a crystal structure with small anisotropy, and the bending workability is improved by improving the elongation. It is disclosed.
Patent Document 5 shows that by integrating the Cube orientation and the Brass, S, and Copper orientations in a Cu-Ni-Si-based alloy, the strength anisotropy is small and the material has excellent bending workability. Has been.

  In the inventions described in Patent Document 1 and Patent Document 2, the analysis of crystal orientation by X-ray diffraction from a specific surface relates to a small part of a specific surface in a distribution of crystal orientations having a certain spread. is there. In the invention described in Patent Document 3, the crystal orientation is controlled by reducing the rolling rate after solution heat treatment. Further, the area of the Cube-oriented crystal grains and the distribution in the plate thickness direction are not described, and bending workability and strength anisotropy are not disclosed. In the invention described in Patent Document 4, the crystal structure in a state by strong cold rolling is recrystallized to realize a crystal structure with small anisotropy, and to realize good bending workability by improving elongation. ing. However, the characteristics are not improved by controlling the crystal orientation. In Patent Document 5, the Cube orientation is 20 to 60%, the average total area ratio of the Brass, S, and Copper orientations is 20 to 50%, the intragranular orientation difference (KAM) is defined, and the structure is controlled. Strength anisotropy is reduced. However, since the surface layer of the plate material is processed by mechanical polishing, the structure of the outermost layer portion cannot be quantified.

  Also, regarding fatigue characteristics among the above requirements, the fatigue characteristics of copper alloys have been improved by increasing the tensile strength (higher strength). There was a limit.

  In Patent Document 6, fatigue properties are improved by controlling the alloy composition and precipitates, but there is a limit to the increase in mechanical strength due to the alloy composition and precipitates. In addition, there is a limit in terms of improving mechanical strength and fatigue characteristics while balancing with bending workability and conductivity.

  Furthermore, a low Young's modulus (longitudinal elastic modulus) is required as one of the characteristic items required for copper alloy materials used for electrical and electronic equipment. In recent years, with the progress of miniaturization of electronic parts such as connectors, the dimensional accuracy of terminals and the tolerance of press working have become severe. By reducing the Young's modulus of the material, the influence of dimensional variation on the contact contact pressure can be reduced, so that the design becomes easy. The Young's modulus is measured by the method of calculating from the slope of the elastic region of the stress-strain diagram by tensile test, and from the slope of the elastic region of the stress-strain diagram when the beam (cantilever) is bent. There are two ways to do this.

JP 2006-009137 A JP 2008-013836 A JP 2006-283059 A JP 2005-350695 A JP 2011-162848 A JP 2004-225112 A

  Thus, there is a demand for a copper alloy material that achieves both bending workability and high strength, has a low Young's modulus, higher fatigue characteristics, and less anisotropy in the parallel and perpendicular directions of each characteristic.

  In view of the above problems, the problem of the present invention is that it is excellent in bending workability as well as strength, has excellent fatigue strength, and has little anisotropy between the rolling parallel direction and the vertical direction of each characteristic. An object of the present invention is to provide a copper alloy plate material suitable for connectors, terminal materials, relays, switches, and the like for lead frames, connectors, terminal materials, and the like for automobiles.

  The present inventors have studied copper alloys suitable for electrical / electronic component applications, and have repeatedly studied to greatly improve bending workability, strength, and conductivity in Cu-Ni-Si based copper alloys. As a result, it was found that there is a correlation between the Cube orientation accumulation ratio and the bending workability. Conventionally, details of the structure of the outermost layer portion in the plate thickness direction have not been shown. When bending a plate material, the deformation amount of the double-sided surface layer of the plate is the largest, so it is expected that the Cube orientation is preferably accumulated on the outermost layer of the plate according to the conventional concept of crystal orientation control. However, as a result of studies by the present inventors, it has been found that if a certain amount of Cube orientation is accumulated inside, even if the Cube orientation of the outermost layer is small, it has excellent bending workability and exhibits a low Young's modulus. . The present invention has been made based on this finding.

That is, the said subject was solved by the following invention.
(1) A copper alloy plate material containing 1.0 to 5.0 mass% Ni, 0.1 to 2.0 mass% Si, and the balance consisting of copper and inevitable impurities, and in crystal orientation analysis in EBSD measurement, The area ratio of the BR orientation {3 6 2} <8 −5 3> in the thickness direction surface layer portion (0t to 1 / 8t) is 5 to 30%, and the thickness inside (1 / 8t to 1 / 2t) Cube azimuth | direction area ratio {1 0 0} <0 0 1> in this is 5% or more, The copper alloy board | plate material characterized by the above-mentioned.
(2) Ni The 1.0~5.0mass%, the Si containing 0.1~2.0mass%, further 0.4 mass% of Sn or less, Zn and 0.5 mass% or less, Ag and 0.2 mass% Hereinafter , Mn is 0.1 mass% or less , B is 0.1 mass% or less , P is 0.01 mass% or less , Mg is 0.1 mass% or less , Cr is 0.2 mass% or less , Zr is 0.01 mass% or less , A copper alloy plate material containing 0.005 to 1.0 mass% in total of at least one selected from the group consisting of 0.01 mass% or less of Fe and 0.005 mass% or less of Hf , with the balance being made of copper and inevitable impurities In the crystal orientation analysis in the EBSD measurement, the area ratio of BR orientation {3 6 2} <8 −5 3> in the thickness direction surface layer portion (0t to 1 / 8t) is 5 to 30%. A copper alloy sheet having a Cube orientation area ratio {1 0 0} <0 0 1> within the sheet thickness (1 / 8t to 1 / 2t) of 5% or more.
(3) The copper alloy sheet according to (1) or (2), wherein, in a plate spring fatigue test of the sheet, the number of repetitions until breakage is 10 ⁷ or more when the applied stress to the material is 500 MPa.
(4) The copper alloy sheet according to any one of (1) to (3), wherein in the 180 ° U bending test of the sheet, bending can be performed without cracks in both the rolling parallel direction and the vertical direction.
(5) A method for producing a copper alloy sheet according to any one of (1) to (4), wherein the copper alloy sheet is cast into a copper alloy material having an alloy composition that gives the copper alloy sheet (Step 1). , Homogenization heat treatment [step 2], hot rolling [step 3], water cooling [step 4], cold rolling 1 [step 6], intermediate annealing [step 7], cold rolling 2 [step 8] and intermediate solution and facilities for heat treatment [step 9] in this order,
Here, the intermediate annealing [Step 7] is performed at a heat treatment temperature of 400 to 600 ° C., and the cold rolling 2 [Step 8] is performed with a surface roughness Ra of 0.5 μm or more and a rolling tension of 100 to A method for producing a copper alloy sheet material, which is performed at 300 MPa .

  The copper alloy sheet of the present invention is excellent in bending workability, exhibits excellent strength, excellent fatigue characteristics, and has little anisotropy in the rolling parallel direction and perpendicular direction of the characteristics, and a lead frame for electrical and electronic equipment, It has properties particularly suitable for connectors, terminal materials, connectors for automobiles, terminal materials, relays, switches, and the like. According to the configuration of the present invention, a copper alloy having excellent strength, bending workability, and electrical conductivity and suitable for use in electrical / electronic equipment can be provided. Moreover, according to the manufacturing method of this invention, the said copper alloy board | plate material can be manufactured suitably.

It is explanatory drawing of the test method of a fatigue characteristic.

  A preferred embodiment of the copper alloy sheet material of the present invention will be described in detail. The “plate material” in the present invention includes “strip material”. Although there is no restriction | limiting in particular in the thickness of the copper alloy board | plate material of this invention, Preferably it is 0.03-0.5 mm. In the present invention, the thickness of the thin plate is not particularly limited, but is preferably 0.04 to 0.3 mm, more preferably 0.05 to 0.25 mm.

  In order to clarify the cause of the occurrence of cracks during bending of the material, the present inventors analyzed the metal structure of the cross section after bending deformation by an electron microscope and electron backscatter diffraction measurement (hereinafter also referred to as EBSD). We investigated in detail. As a result, it was observed that the base material was not uniformly deformed, but non-uniform deformation progressed, in which the deformation was concentrated only in a region having a specific crystal orientation. Then, it was found that due to the non-uniform deformation, wrinkles and cracks having a depth of several μm were generated on the surface of the base material after bending.

  Further, in the 90 ° bending process, strain is applied to the outermost layer in the plate thickness direction, whereas in the 180 ° bending, not only the outermost layer in the plate thickness direction of the thin plate but also the plate thickness 1/8 position (from the plate surface to the plate thickness). 1/8 position, also referred to as 1 / 8t), and not only the crystal grains in the vicinity of the surface layer but also the grains up to the depth of the plate thickness 1/8 position with respect to the local deformation region developed from the surface layer. I found out that I was involved. And the local deformation | transformation zone | band was not observed so much in Cube direction grain, and it turned out that Cube direction has the effect which suppresses nonuniform deformation. As a result, it was found that wrinkles generated on the plate surface were reduced and cracks were suppressed. In addition, it was found that the Brass orientation is often accompanied by local deformation after bending deformation, and adversely affects bendability.

  Up to now, it has been difficult to measure the texture of the outermost layer 0t to the inner 1 / 8t in the thickness direction, but detailed investigation has become possible by improving the polishing method. Since the Cube orientation area ratio in the vicinity of the surface layer (0t to 1 / 8t) could not be analyzed in detail so far, it was difficult to evaluate the influence of the texture here. In the present invention, a method for controlling the texture in the vicinity of the surface layer has been found, and its measurement method and effect have been grasped.

[Area ratio of Cube orientation]
In order to improve the bending workability of the copper alloy sheet material, the present inventors examined the cause of the occurrence of cracks in the bent portion. As a result, the plastic deformation was locally developed to form a shear deformation band, and the generation and connection of microvoids occurred due to local work hardening, resulting in reaching the forming limit. Therefore, as a countermeasure, it has been found that it is effective to increase the proportion of crystal orientation in which work hardening is unlikely to occur in bending deformation. That is, it was found that when the area ratio of the Cube orientation {001} <100> is 5% or more, good bending workability is exhibited. More specifically, the Cube azimuth area ratio may be controlled only inside the plate thickness inside 1 / 8t to 1 / 2t, and the outermost layer does not necessarily have Cube orientation accumulated. When the area ratio of the Cube orientation within the plate thickness is equal to or greater than the lower limit value, the above-described effects are sufficiently exhibited. Moreover, it is preferable that it is more than the said lower limit, since the cold rolling after a recrystallization process does not need to be performed with a low processing rate, and an intensity | strength does not fall remarkably. From the above viewpoint, the preferred range of the area ratio of the (Cube orientation {001} <100> inside the plate thickness (1 / 8t to 1 / 2t) is 5% or more, more preferably 8% or more. The upper limit of the area ratio is not particularly limited, but is practically 50% or less.

  The fact that the bending workability is improved when the Cube orientation area ratio inside the plate thickness (1 / 8t to 1 / 2t) is not less than the above lower limit value has been found by the examination of the present inventors. One of the main reasons is that it was found that 180 ° bending also involved the crystal grains in this region. Furthermore, although it is not certain yet, the reason why the effect of the present invention can be achieved even if the Cube orientation area ratio of the surface layer portion (0t to 1 / 8t) is low is that the suppression of shear band generation that occurs during bending is the thickness of the plate It is presumed that the internal (1 / 8t to 1 / 2t) Cube-oriented grains can bear.

[Cube orientation distribution in the plate thickness direction]
As described above, the distribution of the area ratio in the plate thickness direction of the Cube orientation is controlled to be 5% or more in the plate thickness direction inside (1 / 8t to 1 / 2t), whereby bending workability, low Young's modulus characteristics, Anisotropy can be improved. By controlling the Cube orientation area ratio inside the plate thickness (1 / 8t to 1 / 2t) to 5% or more, generation of shear bands due to bending can be suppressed. Even if the amount of Cube in the surface layer is lower than the inside, the generation of cracks due to the formation of a shear band during bending can be suppressed by the internal structure. That is, even when crystal orientation grains other than the Cube orientation are accumulated on the plate thickness surface layer portion (0 to 1/8 t), the suppression of the shear band generated during bending is suppressed within the plate thickness (1/8 t to 1/2 t). ) Cube orientation grains.

  When a copper alloy sheet is used as a connector, the beam having a spring property and the bending direction are processed in both parallel and vertical directions. Therefore, by reducing the strength in the rolling parallel / vertical direction and the anisotropy of the bending workability, there is an advantage that the mold design and the spring force of the connector are stabilized in any direction. Crystal orientations other than the Cube orientation have different crystal faces in the rolling parallel direction (LD) and the rolling vertical direction (TD). On the other hand, since the Cube orientation preferentially grown in the thickness (1 / 8t to 1 / 2t) of the example of the present invention is directed to the (100) plane of both LD and TD, the strength and bending workability are different. The direction becomes smaller.

[BR orientation]
In the present invention, in addition to the Cube orientation, the BR orientation {3 6 2} <8 −5 3> of the outermost layer (0t to 1 / 8t) is also controlled.
The BR orientation is the orientation that preferentially grows during recrystallization, like the Cube orientation, but the Schmid factor is close to 0.5 in both the rolling parallel direction and the vertical direction compared to the other orientations, reducing the strength of the material. There is a difficulty. However, it can be seen that the BR orientation is a crystal orientation in which the strain difference (KAM value) in the crystal grains is higher than that of other crystal orientations and the average grain area is large, and the accumulation of strain in the elastic region is suppressed. It was confirmed experimentally. Furthermore, it was confirmed that the BR orientation could be accumulated only in the surface layer portion of the plate thickness, and it was found that this improves the fatigue characteristics. The BR orientation is preferably 5 to 30%, more preferably 7 to 25%, in terms of the area ratio of the outermost layer (0t to 1 / 8t) from the balance between reducing strength and excellent fatigue characteristics. .

[Thickness direction distribution of BR orientation]
As described above, the fatigue characteristics can be improved by controlling the distribution of the area ratio in the plate thickness direction of the BR orientation to 5 to 30% in the surface layer portion (0t to 1 / 8t). When the surface area portion (0t to 1 / 8t) has an azimuth area ratio exceeding 30%, the strength is lowered, and further, inhibition of shear band generation that contributes to bending workability is hindered. descend. However, the fatigue characteristics of the material can be improved by accumulating 5 to 30% of the BR orientation in the surface layer portion (0t to 1 / 8t).

[Cube orientation, orientation other than BR orientation]
In addition to the above-mentioned Cube orientation and BR orientation, S orientation {3 2 1} <3 4 6>, Copper orientation {1 2 1} <1 −1 1>, D orientation {4 11 4} <11 −8 11>, Brass orientation {1 1 0} <1 −1 2>, Goss orientation {1 1 0} <0 0 1>, R1 orientation {2 3 6} <3 8 5>, RDW orientation {1 0 2} <0 −1 0> or the like occurs. In the present invention, if the area ratio of the BR orientation and the Cube orientation is within the above range with respect to the observed area of all orientations, it is allowed to include these orientation components.

[EBSD method]
The EBSD method was used for the analysis of the crystal orientation in the present invention. The EBSD method is an abbreviation for Electron BackScatter Diffraction, and is a crystal orientation analysis technique using reflected electron Kikuchi line diffraction that occurs when a sample is irradiated with an electron beam in a scanning electron microscope (SEM). A sample area of 1 micron square containing 200 or more crystal grains was scanned in 0.1 μm steps, and the orientation was analyzed. The measurement area and scan step were set to 300 × 300 μm and 0.1 μm from the size of the crystal grains of the sample. The area ratio of each azimuth is within ± 10 ° from the ideal azimuth of the Cube azimuth {0 0 1} <1 0 0>, and within 10 ° from the ideal azimuth of the BR azimuth {3 6 2} <8 −5 3>. It is a ratio with respect to the total measurement area. The information obtained in the azimuth analysis by EBSD includes azimuth information up to a depth of several tens of nanometers at which the electron beam penetrates into the sample. It was described as an area ratio. Further, since the azimuth distribution changes in the plate thickness direction, it is preferable that the azimuth analysis by EBSD takes an average for any number of points in the plate thickness direction.

[Evaluation of texture distribution in the thickness direction]
In order to investigate the distribution in the sheet thickness direction of the Cube orientation and BR orientation area ratio in the alloy, the measurement was performed by changing the polishing amount. In order to see the structure of the outermost layer portion in the plate thickness direction, the back surface of the test piece is masked and only the surface is electropolished. At this time, polishing is performed while paying attention to the point that the surface of the test piece is mirror-finished and the amount of polishing is minimal. Actually, the polishing amount on the surface of the test piece is 3 μm, which is the outermost layer structure. By fine adjustment of the polishing amount by electrolytic polishing here, it becomes possible to accurately grasp the structure of 0t to 1 / 8t, and detailed analysis can be performed by EBSD analysis. For the internal structure in the thickness direction, the surface of the test piece is mechanically polished and finished to a mirror surface by electrolytic polishing. Thereby, the structure | tissue of 1 / 8t-1 / 2t is obtained, and the measurement in each plate | board thickness direction is attained. The measurement of the prepared test piece was performed by scanning the range of 300 × 300 μm by 0.1 μm step by orientation analysis by EBSD, and measuring the area ratio of Cube orientation and BR orientation.

[Sub-additive elements]
Next, the effect of the secondary additive element on this alloy will be described. Preferred secondary additive elements include Sn, Zn, Ag, Mn, B, P, Mg, Cr, Zr and Hf. The total amount of these elements is preferably 1% by mass or less because no adverse effect of decreasing the electrical conductivity occurs. When these are contained, the total amount is preferably 0.005 to 1.0% by mass and 0.01 to 0.9% by mass in order to fully utilize the additive effect and not lower the electrical conductivity. % Is more preferable, and 0.03 mass% to 0.8 mass% is particularly preferable. The effect of adding each element is shown below.

(Mg, Sn, Zn)
Addition of Mg, Sn and Zn improves the stress relaxation resistance. The stress relaxation resistance is further improved by the synergistic effect when added together than when they are added. In addition, the solder embrittlement is remarkably improved.

(Mn, Ag, B, P)
When Mn, Ag, B, and P are added, the hot workability is improved and the strength is improved.

(Cr, Zr, Fe, Hf)
Cr, Zr, Fe, and Hf are finely precipitated as a compound or simple substance, and contribute to precipitation hardening. Moreover, it precipitates with the magnitude | size of 50-500 nm as a compound, and there exists an effect which makes a crystal grain size fine by suppressing grain growth, and makes bending workability favorable.

[Method for producing copper alloy sheet]
Next, preferable production conditions for the copper alloy sheet of the present invention will be described. In the conventional method for producing a precipitation-type copper alloy, a copper alloy material is cast [Step 1] to obtain an ingot, which is subjected to homogenization heat treatment [Step 2], hot rolling [Step 3], and water cooling [Step] 4], chamfering [Step 5], cold rolling [Step 6] in this order to make a thin plate, intermediate solution heat treatment [Step 9] in a temperature range of 700-1000 ° C. to re-solidify solute atoms After that, the required strength is satisfied by aging precipitation heat treatment [Step 10] and finish cold rolling [Step 11]. In this series of steps, the texture of the material is roughly determined by recrystallization that occurs during the intermediate solution heat treatment, and finally determined by the orientation rotation that occurs during finish rolling.

  In the present embodiment, after hot rolling [Step 3], water cooling [Step 4], chamfering [Step 5], cold rolling 1 [Step 6] is rolled to a rolling rate of 80% or more, and is not recrystallized. Preferably, intermediate annealing [Step 7] is performed at 400 ° C. to 600 ° C. for 5 seconds to 20 hours. Further, moderate strain is applied by cold rolling 2 [Step 8]. By these treatments, the BR orientation of the surface layer portion and the internal Cube orientation area ratio increase in the recrystallization texture of the intermediate solution heat treatment [Step 9]. Further, after the intermediate solution heat treatment [Step 9], an aging precipitation heat treatment [Step 10], finish cold rolling [Step 11], and temper annealing [Step 12] are performed.

Hereinafter, embodiments in which preferable conditions for each step are set in more detail will be described.
An alloy having the target alloy composition is melted in a high-frequency melting furnace, and this is cast at a cooling rate of 0.1 to 100 ° C./second [Step 1] to obtain an ingot. This was subjected to homogenization heat treatment [Step 2] at 800 to 1020 ° C. for 3 minutes to 10 hours, followed by hot working [Step 3], followed by water quenching (corresponding to water cooling [Step 4]) to remove oxide scale. Therefore, chamfering [Step 5] is performed. Then, the cold rolling 1 [process 6] with a processing rate of 80 to 99.8% is performed. Next, intermediate annealing [Step 7] is performed at 400 to 600 ° C. for 5 s to 20 h. Further, in the cold rolling 2 [Step 8], the tension is set to 100 to 300 MPa, the roll roughness Ra of the rolling mill is set to 0.5 μm or more, the rolling rate is set to 5 to 30%, and the entire plate material is strained. Thereafter, heat treatment is performed at 600 to 1000 ° C. for 5 seconds to 1 hour in the intermediate solution heat treatment [Step 9]. In the aging precipitation heat treatment [Step 10], an aging treatment is performed at 400 to 700 ° C. for 5 minutes to 10 hours. Finish cold rolling with a processing rate of 3 to 25% [Step 11] and temper annealing at 200 to 600 ° C. for 5 seconds to 10 hours [Step 12] to obtain the copper alloy sheet of the present invention.

  In the present embodiment, in the hot rolling [Step 3], in the temperature range from the reheating temperature to 700 ° C., the processing for breaking the cast structure and segregation into a uniform structure and the dynamic recrystallization are performed. Processing for miniaturization is performed. In the intermediate annealing [Step 7], after heat treatment to such an extent that the structure in the alloy is not completely recrystallized, in cold rolling 2 [Step 8], in order to control the processing strain in the sheet thickness direction, rolling is performed. In the recrystallized texture in the intermediate solution [Step 9], strain is applied while adjusting the tension and roll roughness in the cuvette, and the Cube-oriented crystal grains within the plate thickness (1 / 8t to 1 / 2t), the plate thickness The BR-oriented crystal grains in the surface layer portion (0t to 1 / 8t) increase.

  Here, if the heat treatment temperature in the intermediate annealing [Step 7] before the intermediate solution [Step 9] is too high, an oxide scale is formed, which is not preferable. Therefore, the heat treatment temperature here is preferably 400 to 600 ° C. Cold rolling 1 [Step 6] is used to add further processing strain, and intermediate annealing [Step 7] is preferably performed at 400 to 600 ° C. for 5 minutes to 20 hours, so that an intermediate solution treatment [Step 9], the Cube orientation area ratio increases in the recrystallized texture. The purpose of the intermediate annealing [Step 7] is to obtain a sub-annealed structure that is not completely recrystallized but partially recrystallized.

  In particular, it is difficult to determine unambiguously, but by specifying the annealing temperature in the intermediate annealing [Step 7], the Cube orientation area ratio tends to increase. In the cold rolling 2 [Step 8], the BR orientation area ratio tends to increase by controlling the roughness Ra of the rolling roll and the tension of the plate during rolling. In this cold rolling 2 [Step 8], preferably, the roughness Ra of the rolling roll is 0.5 μm or more and the tension is 100 MPa or more, so that shear strain is generated in the surface layer portion (0 t to 1/8 t). be introduced. Here, when the roll roughness is too small and the tension is too low, the shear strain is not sufficiently introduced into the surface layer portion (0t to 1 / 8t). When recrystallization is performed in the intermediate solution heat treatment [Step 9] in a state where shear strain is introduced into the surface layer portion, BR orientation grows in the surface layer portion (0t to 1 / 8t). On the other hand, the inside (1 / 8t to 1 / 2t) is subjected to compressive strain in cold rolling 2 [Step 8], and a rolling texture is formed, so that strain-induced grain boundary movement causes intermediate solution. In the chemical heat treatment [Step 9], the Cube orientation grows.

In cold rolling 2 [Step 8], strain is preferably introduced with a tension of 100 to 300 MPa. Here, if the tension is too low, the processing strain is small, the crystal grain size becomes coarse in the intermediate solution heat treatment [Step 9], the bending wrinkles become large, and the characteristics are inferior. If the tension is too high, release of the working strain proceeds and recrystallization occurs, and the development of the Cube-oriented grains in the thickness direction due to strain-induced grain boundary movement becomes non-uniform, resulting in a decrease in bending workability.
After the intermediate solution heat treatment [Step 9], an aging precipitation heat treatment [Step 10], finish cold rolling [Step 11], and temper annealing [Step 12] are performed. In the recrystallized texture, processing is performed to increase the area ratio of the Cube orientation due to strain-induced grain boundary movement. In addition, it contributes to the development of the Cube orientation by controlling the crystal orientation to a certain direction.

[Characteristics of copper alloy sheet]
The copper alloy sheet of the present invention can satisfy the characteristics required for a copper alloy sheet for connectors, for example. In the present invention, the copper alloy sheet preferably has the following characteristics.
-It is preferable that 0.2% yield strength is 700 Mpa or more. More preferably, it is 750 MPa or more. The detailed measurement conditions are as described in the examples unless otherwise specified.
-The bending workability is preferably 180 ° contact U-bend adhesion test, and there is no crack in the bending surface portion in both the rolling parallel and vertical directions. The detailed conditions are as described in the examples unless otherwise specified.
· Fatigue characteristics, at leaf spring fatigue test, it is preferred number of repetitions to failure at the load stress 500MPa is more than 10 ⁷ times. The detailed measurement conditions are as described in the examples unless otherwise specified.
-It is preferable that electrical conductivity is 5% IACS or more. The detailed measurement conditions are as described in the examples unless otherwise specified.
-The Young's modulus is preferably 130 GPa or less. The detailed conditions are as described in the examples unless otherwise specified.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

Example 1
An alloy containing Ni and the like shown in Table 1 and the balance consisting of Cu and inevitable impurities is melted in a high-frequency melting furnace, and this is cast at a cooling rate of 0.1 to 100 ° C./second [Step 1]. An ingot was obtained. This was subjected to a homogenization heat treatment [Step 2] at 800 to 1020 ° C. for 3 minutes to 10 hours, followed by hot working [Step 3] at 1020 to 500 ° C. Thereafter, water quenching (corresponding to water cooling [step 4]) was performed, and chamfering [step 5] was performed to remove oxide scale. Then, cold rolling 1 with a processing rate of 80 to 99.8% [Step 6], then heat treatment at 400 to 600 ° C. for 5 seconds to 20 hours, intermediate annealing [Step 7], and further cold rolling 2 [ Step 8] Apply processing strain at (roll surface roughness 0.5 μm or more, rolling tension 100 to 300 MPa). An intermediate solution treatment [Step 9] was performed at 600 to 1000 ° C. for 5 seconds to 1 hour. Next, an aging precipitation heat treatment [Step 10] is performed at 400 to 700 ° C. for 5 minutes to 1 hour, finish cold rolling at a rolling rate of 3 to 25% [Step 11], and 200 to 600 ° C. for 5 seconds to 10 seconds. Tempering annealing [Step 12] was performed to obtain a specimen. The compositions and properties of these test materials are shown in Tables 1 and 2 for the invention examples and comparative examples. After each heat treatment and rolling, acid cleaning and surface polishing were performed according to the state of oxidation and roughness of the material surface, and correction with a tension leveler was performed according to the shape. In addition, the processing temperature in the hot processing [Step 3] was measured with a radiation thermometer installed on the entry side and the exit side of the rolling mill.

The following property investigation was conducted on this specimen. Here, the final thickness of the test material was 0.08 mm.
a. Cube orientation area ratio Measurement was carried out by EBSD method under the conditions of a measurement area of 9 × 10 ⁴ μm ² and a scan step of 0.5 μm. The scan step was performed in 0.5 μm steps in order to measure fine crystal grains. In the analysis, the 300 × 300 μm EBSD measurement result was divided into 25 blocks, and the Cube orientation area ratio, average crystal grain area, and number of crystal grains in each block were confirmed. The electron beam was generated from thermionic electrons from the W filament of the scanning electron microscope.
Further, in the polishing before the EBSD measurement, the surface layer portion (0t) and the structure of 1 / 8t, 1 / 4t and 1 / 2t are observed. Was observed with EBSD.

b. 180 ° adhesion U-bend test The punch was punched by a press so that the width was 0.25 mm perpendicular to the rolling direction and the length was 1.5 mm. This is W bent so that the bending axis is perpendicular to the rolling direction, GW (Good Way), W bent so as to be parallel to the rolling direction is BW (Bad Way), and 90 ° W bending processing Thereafter, 180 ° contact bending was performed with a compression tester. The bent surface was observed with a 100-fold scanning electron microscope to investigate the presence or absence of cracks. The thing without a crack was judged as O, and the thing with a crack was judged as x.

c. Young's modulus Test pieces were cut out from the rolling parallel direction and the vertical direction, respectively, and processed so that the width was 20 mm, the length was 160 mm, and the parallelism was 0.05 mm or less per 50 mm. The Young's modulus is a value calculated from the slope of the elastic region of the stress-strain diagram obtained by a tensile test.

d. Yield strength [YS]
In the measurement of the deflection coefficient, the yield strength [MPa] was calculated from the indentation amount (displacement) up to the elastic limit of each test piece, and the strength was obtained.
Yield strength (MPa) Y = {(3E / 2) × t × (f / L) × 1000} / L
E: Deflection coefficient, t: Plate thickness, L: Distance between fixed end and load point, f: Displacement (indentation depth)
Here, the anisotropy of a rolling parallel direction and a perpendicular direction was confirmed.

e. Fatigue properties Fatigue properties were measured in the rolling parallel and vertical directions in accordance with JCBA T308; 2001 (Fatigue property test method for copper and copper alloy thin strips). FIG. 1 shows an explanatory diagram (plate spring fatigue test). 1 is a test piece, 2 is a knife edge. The width of the test piece is 10 mm ± 0.2 mm, and the fixing torque of the test piece is 2 N · m at the bottom and 3 N · m at the top. The load stress value of the test piece was obtained by the following formula (a).
The test was performed with a load stress of 500 MPa, and the number of repetitions until the material broke was determined. The case where the number of repetitions until breakage was 10 ⁷ or more in both the rolling parallel and vertical directions was evaluated as “◯”, and either the rolling parallel and vertical directions or both were less than 10 ⁷ times.

σ = (3 × E × t × δ) / (2 × l ² ) (a)
σ: Maximum bending stress (N / mm ² )
δ: Deflection (mm)
l: Test piece set length (mm)
t: Test piece thickness (mm)
E: Deflection coefficient (N / mm ² )

f. Conductivity [EC]
The specific resistance was measured by a four-terminal method in a thermostat kept at 20 ° C. (± 0.5 ° C.) to calculate the conductivity. In addition, the distance between terminals was 100 mm.

About this invention 1-invention example 11 and comparative example 1- comparative example 10, the main raw material Cu, Ni, and Si were mix | blended so that it might become a composition shown in Table 1, and it melt | dissolved and casted.
As shown in Table 2, cold rolling 2 [Step 8] in the production methods of Invention Example 1 to Invention Example 11 had a roll roughness of 0.5 μm or more and a tension of 100 to 300 MPa. As for the structure, the BR orientation area ratio of the surface layer (0t to 1 / 8t) of Invention Example 1 to Invention Example 11 is 5 to 30%, and the Cube orientation area ratio of the inside (1 / 8t to 1 / 2t) is 5%. The above is shown.
In Comparative Examples 1 to 10, a case where the structure (BR orientation, Cube orientation area ratio) defined by the present invention is not satisfied was shown.

As shown in Table 2, Invention Examples 1 to 11 were good in each characteristic. That is, when the Cube orientation area ratio inside the plate thickness (1 / 8t to 1 / 2t) showed 5% or more, all of the 180 ° U-bend, Young's modulus, and yield strength characteristics were good. Furthermore, the BR orientation area ratio in the vicinity of the surface layer (0t to 1 / 8t) was 5 to 30%, and when this was satisfied, the fatigue characteristics were good. Further, the anisotropy of the proof stress in the direction parallel to the rolling direction is within 10 GPa, and the anisotropy is small.
Therefore, the copper alloy plate material of the present invention can be provided as a copper alloy plate material suitable for connectors, terminal materials, relays, switches, etc., such as lead frames, connectors, terminal materials, etc. for automobiles and terminals, etc. it can.

On the other hand, as shown in Table 2, in the sample of the comparative example, one of the characteristics was inferior.
That is, Comparative Examples 1, 5, 7, and 10 have inferior characteristics of 180 ° U bending, Young's modulus, and proof stress anisotropy because the internal Cube orientation area ratio is 5% or less, which is lower than the specified value.
In Comparative Examples 1, 3, 4, 8, and 9, since the BR orientation area ratio of the surface layer portion is 5% or less, the fatigue characteristics are inferior. Since Comparative Example 2, 6, and 7 have the BR orientation of the surface layer part of 30% or more, although fatigue properties are partially excellent, all are inferior because the 180 ° U-bending and the proof stress are lower than the specified values.
In addition, all showed 30 to 45% of electrical conductivity.

1 Test piece 2 Knife edge

Claims (5)

  It is a copper alloy plate material containing 1.0 to 5.0 mass% Ni, 0.1 to 2.0 mass% Si, and the balance consisting of copper and inevitable impurities, and in the crystal orientation analysis in EBSD measurement, the plate thickness direction The area ratio of the BR orientation {3 6 2} <8 −5 3> in the surface layer portion (0t to 1 / 8t) is 5 to 30%, and the Cube inside the plate thickness (1 / 8t to 1 / 2t) A copper alloy sheet characterized by having an orientation area ratio {1 0 0} <0 0 1> of 5% or more. Ni is contained in an amount of 1.0 to 5.0 mass%, Si is contained in an amount of 0.1 to 2.0 mass%, Sn is 0.4 mass% or less , Zn is 0.5 mass% or less , Ag is 0.2 mass% or less , Mn Is 0.1 mass% or less , B is 0.1 mass% or less , P is 0.01 mass% or less , Mg is 0.1 mass% or less , Cr is 0.2 mass% or less , Zr is 0.01 mass% or less , and Fe is 0 .01 mass% or less and Hf containing at least one selected from the group consisting of 0.005 mass% or less in a total of 0.005 to 1.0 mass%, the balance being a copper alloy sheet material made of copper and inevitable impurities, In the crystal orientation analysis in the EBSD measurement, the area ratio of the BR orientation {3 6 2} <8 −5 3> in the thickness direction surface layer portion (0t to 1 / 8t) is 5 to 30%, and the plate thickness A copper alloy sheet having a Cube orientation area ratio {1 0 0} <0 0 1> in the interior (1 / 8t to 1 / 2t) of 5% or more. The copper alloy plate material according to claim 1 or 2, wherein, in a plate spring fatigue test of the plate material, the number of repetitions until breakage is 10 ⁷ times or more when the applied stress to the material is 500 MPa.   The copper alloy sheet according to any one of claims 1 to 3, which can be bent without cracking in both the rolling parallel and vertical directions in a 180 ° U bending test of the sheet. A method for producing a copper alloy sheet according to any one of claims 1 to 4, wherein a copper alloy material comprising an alloy component composition giving the copper alloy sheet is cast [step 1], homogenized heat treatment [ Step 2], hot rolling [Step 3], water cooling [Step 4], cold rolling 1 [Step 6], intermediate annealing [Step 7], cold rolling 2 [Step 8] and intermediate solution heat treatment [Step 9]. ] to facilities in this order,
Here, the intermediate annealing [Step 7] is performed at a heat treatment temperature of 400 to 600 ° C., and the cold rolling 2 [Step 8] is performed with a surface roughness Ra of 0.5 μm or more and a rolling tension of 100 to A method for producing a copper alloy sheet material, which is performed at 300 MPa .

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