JP6671434B2 - Copper alloy for electronic materials - Google Patents

Description

  The present invention relates to a Cu--Co--Si alloy which is a precipitation hardening type copper alloy suitable for use in various electronic components, and particularly proposes a technique capable of improving dimensional accuracy during bending. Is what you do.

  Copper alloys for electronic materials used in various electronic components such as connectors, switches, relays, pins, terminals, and lead frames are required to have both high strength and high conductivity (thermal conductivity) as basic characteristics. You. In recent years, high integration, miniaturization, and thinning of electronic components have rapidly progressed, and accordingly, requirements for copper alloys used for electronic device components have been further enhanced. In particular, in order not to increase the size of the connector, a 0.2% proof stress of 550 MPa or more in the rolling parallel direction and a conductivity of 55% IACS or more are desired.

  From the viewpoint of high strength and high conductivity, the use of precipitation hardening type copper alloys instead of conventional solid solution strengthened copper alloys such as phosphor bronze and brass as copper alloys for electronic materials is increasing. . In precipitation hardening type copper alloys, by aging the solution-treated supersaturated solid solution, fine precipitates are uniformly dispersed, the strength of the alloy is increased, and the amount of solid solution elements in copper is reduced. Electric conductivity is improved. For this reason, a material having excellent mechanical properties such as spring properties and good electrical and thermal conductivity can be obtained.

Among precipitation hardening type copper alloys, Cu-Ni-Si alloys, which are generally referred to as Corson alloys, are typical copper alloys having relatively high conductivity, strength, and bending workability. One of the alloys that are being actively developed. In this copper alloy, strength and conductivity can be improved by precipitating fine Ni-Si-based intermetallic compound particles in a copper matrix.
As such a Corson alloy, a Cu-Co-Si alloy in which Ni is replaced by Co has been proposed for the purpose of further improving the characteristics.

  A Cu-Co-Si alloy relates to general bending workability, and Patent Documents 1 and 2 disclose a technique of controlling the crystal orientation using a Cu-Co-Si alloy.

  Specifically, in Patent Document 1, in the crystal orientation analysis in EBSD (Electron Back-Scatter Diffraction: electron backscatter diffraction) measurement, the area ratio of Brass orientation {110} <112> is 20% or less, and Copper orientation {121 The area ratio of {<111> is 20% or less, the area ratio of Cube orientation {001} <100> is 5 to 60%, the 0.2% proof stress is 500 MPa or more, and the conductivity is 30% IACS or more. Are described. Patent Document 2 discloses a copper alloy sheet material characterized in that, in a crystal orientation analysis by EBSD measurement, an area ratio of a cube orientation {001} <100> is 7 to 47%, and further, an S orientation {231銅 <346> describes a copper alloy sheet material having an area ratio of 5 to 40%.

JP 2011-017072 A Japanese Patent No. 4875768

  However, although the copper alloy sheets according to Patent Documents 1 and 2 are excellent in bending workability, it is considered that there is still an insufficient point in springback at the time of bending. Springback is a phenomenon in which deformation of the material slightly returns when the forming tool is separated from the material in bending. Springback adversely affects the dimensional accuracy of the finished part.

  The copper alloy sheets according to Patent Documents 1 and 2 have improved bendability by developing a Cube orientation {001} <100>, but have a Young's modulus of a material having a Cube orientation {001} <100> developed. Tends to decrease. On the other hand, the amount of springback is proportional to the yield stress of the material and inversely proportional to the Young's modulus. Therefore, if the Cube orientation {001} <100> is developed, the springback increases.

As described above, the copper alloy sheets according to Patent Literatures 1 and 2 did not have sufficient dimensional accuracy of finished parts due to springback during bending.
As a countermeasure against springback, there is a method of forming a V-notch in a bent portion before bending the alloy. However, the strength of the bent portion is inevitably reduced and cracks are easily generated.

  An object of the present invention is to solve such a problem, and an object of the present invention is to provide a material having 0.2% proof stress, electrical conductivity, and bendability suitable for use in electronic materials, and at the time of bending. An object of the present invention is to provide a highly reliable copper alloy for electronic materials in which springback is suppressed.

  As a result of intensive studies, the inventor of the present invention has determined that, in a Cu-Co-Si alloy, a predetermined position obtained by performing equal area division used for display by a vector method on a stereo triangle representing a crystal orientation in a direction perpendicular to rolling. It has been found that by controlling the degree of integration of crystal orientation, springback during bending can be suppressed. And it has been newly obtained that the control of the degree of integration of the crystal orientation can be realized by adjusting processing conditions such as homogenization annealing, hot rolling and solution treatment.

Based on the above findings, the present invention contains 0.5 to 3.0% by mass of Co, contains Si so that Co / Si is 3 to 5 by mass, and the balance is copper and inevitable. Nos. 1, 33, and 36 obtained by performing equal area division on a stereo triangle that is composed of chemical impurities and indicates the crystal orientation in the direction perpendicular to the rolling direction (TD) obtained from the EBSD measurement and used in the display by the vector method. When the degrees of integration of the crystal orientations are S ₁ , S ₃₃ , and S ₃₆ , respectively,
S = S ₃₃ / (S ₁ + S ₃₆ ) ≧ 0.5
Is a copper alloy for electronic materials that satisfies the following relationship.

  In the 90 ° Badway W bending test based on JIS H3130 (2012), the copper alloy for electronic materials of the present invention sets the actual bending deformation angle of the bent portion (the center portion among the three portions) of the bending test piece to θ (°). ), The value of θ-90 ° indicating the springback angle Δθ is preferably 5 ° or less.

  The copper alloy for electronic materials of the present invention conforms to JIS B0601 (2013) on the outer peripheral surface of a bent portion (the center portion among three locations) of a bending test piece in a 90 ° Badway W bending test based on JIS H3130 (2012). It is preferable that the compliant surface average roughness Ra is 1.0 μm or less.

  It is preferable that the copper alloy for electronic materials of the present invention further contains 0.5% by mass or less of Cr.

  The copper alloy for electronic materials of the present invention further comprises Zn and Sn in an amount of 0 to 0.5% by mass, Ni in an amount of 0 to 0.1% by mass, and Mg, Mn, Fe, Ti, Al, P and B in an amount of 0% respectively. 0.2% by mass, and the total of at least one selected from Zn, Sn, Ni, Mg, Mn, Fe, Ti, Al, P and B is 1.0% by mass or less. Is preferred.

  Further, the present invention also provides an electronic component provided with the copper alloy for electronic materials of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, while having suitable 0.2% proof stress, electrical conductivity, and bending workability, the copper alloy for electronic materials with high reliability which suppressed the springback at the time of bending can be provided.

FIG. 1 shows a stereo projection display of rotation angles in the Williams method and the vector method representing the crystal orientation. FIG. 2 shows a stereo triangle divided into 36 by equal area division.

Hereinafter, embodiments of the present invention will be described in detail.
The copper alloy for an electronic material according to one embodiment of the present invention contains 0.5 to 3.0% by mass of Co, and contains Si so that Co / Si is 3 to 5 in a mass ratio, A box number obtained by performing an equal area division using a vector method with respect to a stereo triangle representing the crystal orientation in the direction perpendicular to the rolling direction (TD) obtained from EBSD measurement, with the balance being copper and unavoidable impurities. When the integration degrees of the crystal orientations of ₁ , ₃₃ and ₃₆ are S ₁ , S ₃₃ and S ₃₆ , respectively,
S = S ₃₃ / (S ₁ + S ₃₆ ) ≧ 0.5
Satisfy the relationship.

(Co addition amount)
Co and Si are precipitated in the matrix as Co ₂ Si by performing an appropriate heat treatment, thereby increasing the strength without deteriorating the conductivity. However, when the Co concentration is less than 0.5% by mass, the precipitation hardening becomes insufficient, and the desired strength cannot be obtained even when the other component is added. When the Co concentration exceeds 3.0% by mass, sufficient strength is obtained, but conductivity, bending workability, and hot workability decrease.
Preferably, the content is 1.0 to 2.5 mass% Co.

(Amount of Si added)
Si is adjusted so that Co / Si is 3 to 5 in mass ratio. With the above ratio, both strength and conductivity after precipitation hardening can be improved. If the above ratio exceeds 5, the precipitation of Co ₂ Si in the aging treatment becomes insufficient, and the strength decreases. If the above ratio is less than 3, Si that does not precipitate as Co ₂ Si will form a solid solution in the mother phase, and the conductivity will decrease.

(Cr addition amount)
Cr precipitates preferentially at the crystal grain boundaries in the cooling process at the time of melting casting, so that the grain boundaries can be strengthened, cracks are less likely to occur at the time of hot working, and a reduction in yield can be suppressed. Cr precipitated at the grain boundary during melt casting is re-dissolved by solution treatment or the like, but precipitates particles having a bcc structure containing Cr as a main component or a compound with Si during the subsequent aging precipitation. In a normal Cu-Co-Si-based alloy, of the amount of Si added, Si that did not contribute to aging precipitation suppresses an increase in electrical conductivity while being dissolved in the mother phase. By adding and further precipitating silicide, the amount of solid solution Si can be reduced, and the conductivity can be increased without impairing the strength. However, when the Cr concentration exceeds 0.5% by mass, coarse second phase particles are easily formed, which impairs product characteristics. Therefore, in the present invention, Cr can be added at a maximum of 0.5% by mass. However, if the content is less than 0.03% by mass, the effect is small. Therefore, it is preferable to add 0.03 to 0.5% by mass, more preferably 0.09 to 0.3% by mass.

(Amount of Sn and Zn added)
Addition of a small amount of Sn and Zn also improves the product characteristics such as strength, stress relaxation characteristics and plating properties without impairing the conductivity. The effect of addition is exerted mainly by solid solution in the parent phase. However, when the respective concentrations of Sn and Zn exceed 0.5% by mass, the effect of improving characteristics is saturated, and the productivity is impaired. In addition, the desired orientation cannot be obtained in the product, and the bending workability decreases. Therefore, in the present invention, Sn and Zn can each be added at a maximum of 0.5% by mass. However, since the effect is small when the total of Sn and Zn is less than 0.05% by mass, the total of Sn and Zn is preferably 0.05 to 1.0% by mass, more preferably 0.1 to 0.5%. % By mass.

(Addition amount of Ni)
Ni is precipitated in the mother phase as Ni ₂ Si by performing an appropriate heat treatment, thereby improving the strength of the alloy. However, if the concentration of Ni exceeds 0.1% by mass, the conductivity is impaired, so the amount of Ni added is preferably 0.02 to 0.1% by mass.

(Addition amounts of Mg, Mn, Fe, Ti, Al, P and B)
Mg, Mn, Fe, Ti, and Al, when added in small amounts, improve product properties such as strength and stress relaxation properties without impairing conductivity. P has a deoxidizing effect, B has an effect of refining the cast structure, and has an effect of improving hot workability. The effect of the addition is mainly exhibited by the solid solution in the mother phase, but further effects can be exhibited by being contained in the second phase particles. However, when the respective concentrations of Mg, Mn, Fe, Ti, Al, P and B exceed 0.2% by mass, the effect of improving characteristics is saturated, and the productivity is impaired. Therefore, in the present invention, Mg, Mn, Fe, Ti, Al, P and B can be added in a maximum of 0.2% by mass. However, since the effect is small when the total of Mg, Mn, Fe, Ti, Al, P and B is less than 0.01% by mass, the total of Mg, Mn, Fe, Ti, Al, P and B is preferably It can be 0.01 to 0.5% by mass, more preferably 0.04 to 0.2% by mass.

  When containing Zn, Sn, Ni, Mg, Mn, Fe, Ti, Al, P and B described above, they are selected from those Zn, Sn, Ni, Mg, Mn, Fe, Ti, Al, P and B. The total of at least one type is 1.0% by mass or less. By setting the total to 1.0% by mass or less, the electric conductivity can be favorably maintained.

(0.2% proof stress)
In order to satisfy the characteristics required for a predetermined electronic material such as a connector, the 0.2% proof stress in the rolling parallel direction is preferably 550 MPa or more, more preferably 580 MPa or more. Although the upper limit of the 0.2% proof stress is not particularly limited, it is typically 800 MPa or less to achieve a conductivity of 55% IACS or more.
The 0.2% proof stress is measured using a tensile tester according to JIS Z2241.

(conductivity)
The conductivity is 55% IACS or more. Thereby, it can be effectively used as an electronic material. The conductivity can be measured by a four-terminal method according to JIS H0505. The conductivity is preferably 60% IACS or more.

(Degree of integration of crystal orientation)
The degree of integration of the crystal orientations of box numbers 1, 33, and 36 obtained by performing equal area division used in the display by the vector method on the stereo triangle indicating the crystal orientation in the direction perpendicular to the rolling direction (TD) is S _1. , S ₃₃ and S ₃₆ ,
S = S ₃₃ / (S ₁ + S ₃₆ ) ≧ 0.5
Is satisfied, the bending workability is improved, and springback during bending can be effectively suppressed.
Here, S ₁ corresponds to the <001> direction, S ₃₃ corresponds to the <221> direction, and S ₃₆ corresponds to the <111> direction.
Although the reason is not always clear and is presumed to the last, the Schmid factor representing the easiness of plastic deformation of the crystal is 0.41 in S ₃₃ : <221>, and in the S ₃₆ : <111> direction. Since it is 0.27, it is considered that the bendability can be improved by reducing the degree of integration of S _{36 having} a small Schmid factor and increasing the degree of integration of S _{33 having} a large Schmid factor. The S _1: <001> is to increase according to the accumulation of Cube orientation {001} <100> to bring an adverse effect on the spring-back is believed to be reduce spring back by reducing the degree of integration S _1. In this respect, S is preferably set to 1.0 or more, and more preferably 2.0 or more.
The degree of integration of the crystal orientation is obtained from the EBSD measurement. FIG. 1 is a stereo projection display of a rotation angle of a vector method (biaxial pole diagram) representing a crystal orientation of a copper alloy. In FIG. 1, a point TD representing the rolling perpendicular direction (TD) on the surface of the copper alloy sheet is indicated by coordinates (ψ, λ) on the stereo triangle (T1) on which the point TD is placed. FIG. 2 shows this stereo triangle divided into 36 by equal area division (by Ruer et al.). Among the crystal orientations in the stereo triangle of FIG. 2, the one in the region indicated by number 1 is “the crystal orientation of box number 1” (Furubayashi, “Recrystallization and Material Structure”, 1st edition, Ryo Uchida) Crane field, see pages 88-89). Further, “the degree of integration of the crystal orientation of box number 1” represents the average intensity of the section on the pole figure represented by the orientation corresponding to box number 1. The crystal orientations of box numbers 33 and 36 are similarly defined.

(Spring back angle Δθ)
The fact that the springback angle Δθ is small indicates that springback during bending is effectively suppressed. From this viewpoint, the springback angle Δθ is set to 5 ° or less, preferably 4.0 ° or less, and more preferably 3.5 ° or less.
The springback angle Δθ is defined as θ (°) in a 90 ° Badway W bending test based on JIS H3130 (2012), where the actual bending deformation angle of a bent portion (the center portion among three locations) of a bending test piece is defined as θ (°). , Θ-90 °.

(Round surface roughness Ra of the bent part)
Since there is a phenomenon in which minute irregularities on the surface of the material start to grow into cracks, if the surface roughness Ra of the outer peripheral surface of the bent portion is small, growth into cracks is difficult and bending is easy. From this viewpoint, the outer peripheral surface roughness Ra of the bent portion is set to 1.0 μm or less, preferably 0.8 μm or less, and more preferably 0.6 μm or less.
In the 90 ° BadwayW bending test based on JIS H3130 (2012), the outer peripheral surface roughness Ra of the bent portion is JIS B0601 (2013) for the outer peripheral surface of the bent portion (the center portion among three places) in the bent test piece. Can be measured in accordance with

(Production method)
As described above, the Cu-Co-Si-based alloy is formed by sequentially performing an ingot manufacturing process, a homogenizing annealing process, a hot rolling process, a cold rolling process, a solution treatment process, an aging treatment process, and a final cold rolling process. Can be produced. In addition, after hot rolling, it is possible to perform facing as needed.

  Specifically, first, raw materials such as electrolytic copper, Co, and Si are melted using an air melting furnace or the like to obtain a molten metal having a desired composition. And this molten metal is cast into an ingot. After that, hot rolling is performed, and solution treatment, aging treatment (450 to 550 ° C. for 1 to 24 hours), and final cold rolling (deformation degree of 10 to 50%) are performed. After the final cold rolling, strain relief annealing may be performed. The strain relief annealing can be usually performed in an inert atmosphere such as Ar at 400 to 600 ° C. for 0.5 to 5 minutes. After the solution treatment, cold rolling and aging may be performed in this order.

Here, in this manufacturing method, it is important to perform homogenizing annealing, hot rolling and solution treatment under predetermined conditions after manufacturing the ingot. In the prior art, since the conditions of these steps were not optimized, characteristics such as those of the present invention could not be obtained, and in particular, springback could not be significantly suppressed.
Hereinafter, the respective steps of the homogenization annealing, hot rolling, and solution treatment will be described in detail. Note that the other steps can be performed under the conditions usually employed in the manufacturing process of the Cu—Co—Si alloy.

<Ingot production>
Melt casting is generally performed in an atmospheric melting furnace, but can be performed in a vacuum or in an inert gas atmosphere. After dissolving the electrolytic copper, raw materials are added according to the composition of each sample such as Co, Si, etc., and the mixture is kept for a certain period of time after stirring to obtain a molten metal having a desired composition. Then, after the molten metal is adjusted to 1250 ° C. or higher, it is cast into an ingot. Other than Co and Si, Cr is 0.5% by mass or less, and at least one selected from Zn, Sn, Ni, Mg, Mn, Fe, Ti, Al, P and B is 1.0% by mass or less in total. Can also be added.

<Homogenizing annealing>
By performing the homogenization annealing at an appropriate temperature and for an appropriate time, coarse Co—Si particles generated at the time of casting can be solid-dissolved in the matrix and the stacking fault energy can be reduced. A material having low stacking fault energy is difficult to cross-slip, so that dynamic recovery hardly occurs and dislocations are easily accumulated. In the subsequent hot rolling, dynamic recrystallization occurs using the accumulated dislocations as a driving force, and the crystal grains are refined. In order to obtain a desired degree of crystal orientation (S ₃₃ / (S ₁ + S ₃₆ ) ≧ 0.5) in the product, it is preferable that the crystal grain size at the end of the hot rolling be small. If the temperature of the homogenization annealing is too high, the material may be melted, and the dynamic recrystallization proceeds too much and the crystal grains at the end of hot rolling become coarse, resulting in the accumulation of the desired crystal orientation in the product. I can not get the degree. If the temperature of the homogenization annealing is too low, coarse Co—Si particles cannot be dissolved in the matrix, and the desired orientation cannot be obtained in the product. Specifically, the homogenization temperature is preferably 950 to 1025 ° C, and the time is preferably 1 to 24 hours.

<Hot rolling>
The ingot after the completion of the homogenization annealing is extracted from the furnace and subjected to hot rolling. By increasing the rolling strain rate ε (sec ⁻¹ ) in the final pass of hot rolling, it is possible to perform strong working with larger energy, and to reduce the crystal grain size at the end of hot rolling by dynamic recrystallization. be able to. Here, the rolling strain rate ε is expressed by the following equation.
In the formula, n: roll rotation speed (rpm), r: reduction ratio, R: roll radius (mm), H ₀ : entry side plate thickness (mm). If the strain rate ε is too low, the crystal grains at the end of the hot rolling are insufficiently refined, and the product cannot have the desired degree of integration of the crystal orientation. If the strain rate ε is too high, the load applied to the rolling mill becomes excessive, which is not practical. Specifically, the strain rate is 30 to 60 sec ^-1 , preferably 40 to 60 sec ^-1 .
The cooling rate from the end of hot rolling to 400 ° C. is preferably 7 to 15 ° C./sec. If this is not satisfied, the bending workability of the product will decrease, and the springback will increase. The cooling rate is more preferably 10 to 15 ° C./sec.

<Solution treatment>
The purpose of the solution treatment is to increase the age hardening ability after the solution treatment by dissolving the Co-Si particles precipitated during hot rolling. If the temperature of the solution treatment is too low, these precipitates cannot be sufficiently solid-dissolved, and a predetermined strength cannot be obtained. In addition, the degree of integration in the direction corresponding to the box number 33 does not sufficiently develop, and the bending workability decreases. If the temperature of the solution treatment is too high, the effect of pinning the grain boundaries by the precipitates is lost, and the crystal grains become coarse and the strength decreases. In addition, the degree of integration in the direction corresponding to box number 1 is increased, and the springback during bending is increased. As the temperature of the solution treatment, it is preferable to heat the copper alloy material before the solution treatment to a temperature near the solid solubility limit of the second phase particle composition. Specifically, it heats at 850-1000 degreeC for 0.5 to 10 minutes. Further, from the viewpoint of preventing precipitation of the second phase particles and coarsening of recrystallized grains, it is preferable that the cooling rate after the solution treatment is as high as possible. Specifically, the average cooling rate when the material temperature decreases from the solution treatment temperature to 400 ° C. is preferably 15 ° C./sec or more, and more preferably 50 ° C./sec or more.

<Aging treatment>
Subsequent to the solution treatment, a desired strength and electrical conductivity can be obtained by performing an aging treatment so that precipitates of an appropriate size are uniformly distributed. When the temperature of the aging treatment is lower than 450 ° C., the conductivity is low, and when the temperature is higher than 550 ° C., the strength is low. The time of the aging treatment is preferably 1 to 24 hours. The aging treatment is preferably performed in an inert atmosphere of Ar, N ₂ , H ₂ or the like in order to suppress the formation of an oxide film.

<Final cold rolling>
By performing final cold rolling after the aging treatment, dislocations are introduced to increase the strength. The higher the degree of rolling, the higher the strength of the material. However, if the degree of rolling is too high, the proportion of crystal grains having shear bands increases, and the bending workability deteriorates. Therefore, in order to obtain a good balance between strength and bending workability, the final degree of cold rolling is set to 10 to 50%, preferably 20 to 40%.

<Strain removal annealing>
By performing strain relief annealing subsequent to the final cold rolling, residual stress generated in the material during processing can be removed, and the spring property is improved. If the holding temperature of the strain relief annealing is too high, or if the holding time is too long, coarse Co—Si particles are precipitated and the strength is reduced. The holding temperature is 400 to 600 ° C, preferably 450 to 550 ° C. The holding time is 0.5 to 5 min, preferably 1 to 3 min.

  In addition, steps such as grinding, polishing, and shot blast pickling for removing oxide scale on the surface can be appropriately performed between the above steps.

  The Cu-Co-Si-based alloy of the present invention can be processed into various copper products, for example, plates, strips, tubes, rods, and wires. , Pins, terminals, relays, switches, and electronic components such as foil materials for secondary batteries. In particular, high dimensional accuracy can be obtained at the time of pressing when manufacturing a connector.

  Next, a copper alloy for an electronic material according to the present invention was experimentally manufactured and its performance was confirmed. However, the description here is for the purpose of illustration only, and is not intended to be limiting.

A copper alloy having a component composition shown in Table 1 was melted at 1300 ° C. using a high-frequency melting furnace, and cast into an ingot having a thickness of 30 mm. Next, the ingot was homogenized under the conditions shown in Table 1, and then hot-rolled to a thickness of 10 mm at a rolling strain rate shown in Table 1, and the hot-rolling termination temperature was set to 900 ° C. After the completion of the hot rolling, the material was cooled with water at an average cooling rate shown in Table 1 until the material temperature reached 400 ° C., and then left standing in air for cooling. After removing the surface to 9 mm in thickness for scale removal, cold rolling was performed, solution treatment was performed under the conditions shown in Table 1, and then aging treatment was performed at 500 ° C. for 12 hours. A plate having a thickness of 0.1 mm was obtained by performing final cold rolling at a working ratio of ５０50%. Finally, strain relief annealing was performed at 500 ° C. for 1 minute.
The following characteristics were evaluated for each of the test pieces thus obtained. Table 2 shows the results.

<Strength (0.2% proof stress)>
Each test piece was subjected to a tensile test in the rolling parallel direction based on JIS Z2241 to measure a 0.2% proof stress (YS: MPa).
<Conductivity>
The conductivity (EC:% IACS) was determined by measuring the volume resistivity using a double bridge in accordance with JIS H0505.
<Degree of integration of crystal orientation>
The degree of integration of crystal orientation was evaluated using EBSD measurement. First, a test piece was cut into a square of 20 mm, and the surface of the rolled surface was electropolished in a solution of 67% phosphoric acid + 10% sulfuric acid at a voltage of 15 V for 60 seconds to reveal a structure. JXA8500F manufactured by JEOL Ltd. was used for the measurement. The normal direction (ND) of the rolling surface of the test piece was inclined by 70 ° with respect to the incident electron beam, and the perpendicular direction (TD) of the test piece was set according to the tilt direction of the sample holder. Then, the focused electron beam was irradiated on the inclined surface. Acceleration voltage: 15.0 kV, irradiation current amount: 5 × 10 ⁻⁸ A, working distance: 15 mm, measurement is performed at n = 5 in an observation visual field of 500 μm × 500 μm (step width: 1 μm), and the average value is calculated. Measured values. The measurement program used TSL OIM data collection, and the analysis program used TSL OIM Analysis. Integration of crystal orientations of box numbers 1, 33, and 36 obtained by performing equal area division used for display by the vector method on a stereo triangle obtained when an inverse pole figure is photographed from the direction perpendicular to the rolling direction (TD). The degrees were S ₁ , S ₃₃ and S ₃₆ , respectively, and the value of S = S ₃₃ / (S ₁ + S ₃₆ ) was evaluated.
<Bendability (surface average roughness Ra after bending)>
According to JIS H3130 (2012), a W bending test was performed with Badway (bending axis parallel to the rolling direction) and R / t = 1.0 (t = 0.1 mm), and the outer peripheral surface of the bending portion of the test piece was observed. did. As the observation method, the outer peripheral surface of the bent portion was photographed using a confocal microscope HD100 manufactured by Lasertec, and the average roughness Ra (based on JIS B0601 (2013)) was measured using attached software, and compared. When the sample surface before bending was observed using a confocal microscope, the average roughness Ra was 0.2 μm or less in all cases.
The case where the surface average roughness Ra after bending was 1.0 μm or less was evaluated as ○, and the case where Ra exceeded 1.0 μm was evaluated as x.
<Spring back angle Δθ>
With respect to a test piece subjected to 90 ° W bending in the Badway direction in accordance with JIS H3130 (2012), a bending section was observed using a microscope VW-6000 manufactured by KEYENCE, and a bending angle θ (deg) was measured. The difference [theta] -90 [deg.] Between this bending angle and the bending angle (= 90 [deg.]) When a load was applied by the mold was defined as the springback angle [Delta] [theta] (deg).

As shown in Tables 1 and 2, in all of Invention Examples 1 to 20, S = S ₃₃ / (S ₁ + S ₃₆₎ by performing homogenization annealing, hot rolling, solution treatment, and the like under predetermined conditions. ) ≧ 0.5. As a result, it was possible to obtain a material having good bending workability in the BW direction and small springback.

In Comparative Example 1, since the strain rate of the hot rolling was too low, S = S ₃₃ / (S ₁ + S ₃₆ ) was small, and the outer peripheral surface roughness Ra and the springback angle Δθ of the bent portion were deteriorated.
In Comparative Example 2, since the strain rate of hot rolling was too high, cracks occurred in the hot plate, and a product could not be obtained.
In Comparative Example 3, since the temperature in the homogenization treatment was too low, coarse Co—Si particles could not be dissolved in the matrix, and S = S ₃₃ / (S ₁ + S ₃₆ ) was reduced to 0. .2% proof stress, the surface roughness Ra of the outer periphery of the bent portion and the springback angle Δθ were deteriorated.
In Comparative Example 4, since the temperature in the homogenization treatment was too high, the crystal grains after hot rolling became coarse, S = S ₃₃ / (S ₁ + S ₃₆ ) became small, and the outer peripheral surface roughness of the bent portion was reduced. Ra and the springback angle Δθ deteriorated.
In Comparative Examples 5 and 6, since the cooling rate after hot rolling was not appropriate, S = S ₃₃ / (S ₁ + S ₃₆ ) was reduced, and the 0.2% proof stress and the outer peripheral surface roughness Ra of the bent portion were reduced. And the springback angle Δθ deteriorated.
In Comparative Example 7, since the temperature in the solution treatment was too high, the 0.2% proof stress was deteriorated, S = S ₃₃ / (S ₁ + S ₃₆ ) was reduced, and the springback angle Δθ was deteriorated.
In Comparative Example 8, since the temperature in the solution treatment was too low, the 0.2% proof stress deteriorated, S = S ₃₃ / (S ₁ + S ₃₆ ) became small, and the outer peripheral surface roughness Ra of the bent portion deteriorated. did.
In Comparative Examples 9 and 10, the Co content deviated from the predetermined range, and thus the 0.2% proof stress, the electrical conductivity, or the surface roughness Ra of the bent portion deteriorated.
In Comparative Examples 11 and 12, 0.2% proof stress or electrical conductivity was low due to Co / Si falling out of a predetermined range in mass ratio.
In Comparative Example 13, the conductivity was deteriorated because the mass of the additional element other than Co and Si was too large. In addition, S = S ₃₃ / (S ₁ + S ₃₆ ) became small, and the outer peripheral surface roughness Ra of the bent portion deteriorated.

  As described above, according to the present invention, a highly reliable copper alloy for electronic materials having 0.2% proof stress, electrical conductivity, and bendability suitable for use in electronic materials and suppressing springback during bending. Was obtained.

Claims (6)

It contains 0.5 to 3.0% by mass of Co, contains Si so that Co / Si becomes 3 to 5 by mass, and the balance consists of copper and unavoidable impurities, and EBSD (Electron Back Scatter). (Diffraction: electron backscatter diffraction) Box numbers 1 and 33 obtained by performing equal area division on a stereo triangle representing the crystal orientation in the direction perpendicular to the rolling direction (TD) obtained from the measurement, using the vector method. Assuming that the degrees of integration of the crystal orientations of 36 are S ₁ , S ₃₃ , and S ₃₆ respectively,
S = S ₃₃ / (S ₁ + S ₃₆ ) ≧ 0.5
Copper alloys for electronic materials that satisfy the following relationship.   In a 90 ° Badway W bending test based on JIS H3130 (2012), when an actual bending deformation angle of a bending portion (center portion among three places) of a bending test piece is defined as θ (°), a springback angle Δθ is defined as: The copper alloy for electronic materials according to claim 1, wherein the value of θ-90 ° shown is 5 ° or less.   In the 90 ° Badway W bending test based on JIS H3130 (2012), the surface average roughness Ra based on JIS B0601 (2013) on the outer peripheral surface of the bent portion (the center part among three places) of the bending test piece is 1. The copper alloy for electronic materials according to claim 1, wherein the thickness is 0 μm or less.   The copper alloy for an electronic material according to any one of claims 1 to 3, further containing 0.5% by mass or less of Cr.   Furthermore, Zn and Sn are each contained in an amount of 0 to 0.5% by mass, Ni is contained in an amount of 0 to 0.1% by mass, and Mg, Mn, Fe, Ti, Al, P and B are each contained in an amount of 0 to 0.2% by mass. The total of at least one selected from Zn, Sn, Ni, Mg, Mn, Fe, Ti, Al, P and B is 1.0% by mass or less according to any one of claims 1 to 4. The copper alloy for an electronic material according to the above.   An electronic component comprising the copper alloy for an electronic material according to claim 1.