JP2018162510A - Copper alloy for electronic material, and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy for an electronic material with high reliability, having 0.2% proof stress and conductivity appropriate when used in an electronic material, while improving flexure processability and fatigue characteristics.SOLUTION: A copper alloy for an electronic material includes 0.5-3.0 mass% Co, 0.1-1.0 mass% Ni and 0.1-1.5 mass% Si with a mass ratio (Ni/Co) of Ni to Co being 0.1-1.0 and (Ni+Co)/Si being 3-5 by a mass ratio, and the balance copper with inevitable impurities. An orientation difference between neighboring measurement points (KAM value) obtained by EBSD (Electron Back Scatter Diffraction) measurement is 1.4-2.6 and a standard deviation of the KAM value is 1.2 or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a Cu—Co—Ni—Si alloy which is a precipitation hardening type copper alloy suitable for use in various electronic components, and in particular, 0.2% proof stress and conductivity suitable for electronic materials. The present invention proposes a highly reliable copper alloy for electronic materials having improved bending workability and fatigue characteristics.

  Copper alloys for electronic materials used in various electronic parts such as connectors, switches, relays, pins, terminals, and lead frames are required to have both high strength and high conductivity (or thermal conductivity) as basic characteristics. Is done. In recent years, electronic parts have been highly integrated, miniaturized and thinned, and the demand for copper alloys used in electronic equipment parts has further increased. In particular, in order not to increase the size of the connector, a 0.2% proof stress in the rolling parallel direction of 650 MPa or more and a conductivity of 50% IACS or more are desired.

  From the viewpoint of high strength and high conductivity, the amount of precipitation hardening type copper alloys used in place of solid solution strengthened copper alloys represented by conventional phosphor bronze, brass, etc. is increasing as copper alloys for electronic materials. . In precipitation-hardened copper alloys, by aging the supersaturated solid solution that has undergone solution treatment, fine precipitates are uniformly dispersed, increasing the strength of the alloy and reducing the amount of solid solution elements in the copper. Electrical conductivity is improved. For this reason, it is possible to obtain a material having excellent mechanical properties such as springiness and excellent electrical conductivity and thermal conductivity.

Of the precipitation hardening type copper alloys, Cu—Ni—Si alloys generally referred to as Corson alloys are representative copper alloys having relatively high electrical conductivity, strength, and bending workability. It is one of the actively developed alloys. In this copper alloy, strength and conductivity can be improved by precipitating fine Ni—Si intermetallic compound particles in a copper matrix.
In such a Corson alloy, a Cu—Co—Si alloy in which Co is added or Ni is replaced with Co has been proposed for the purpose of further improving the characteristics.

  For example, in patent document 1 (Unexamined-Japanese-Patent No. 2013-067849), it contains Co: 0.5-3.0 mass%, Si: 0.1-1.0 mass%, Co / Si mass ratio: 3. For Cu—Co—Si based copper alloy strips of 0 to 5.0, the balance being copper and inevitable impurities, the hardness B (Hv of the structure M1 of the thickness center C in the rolling parallel direction RD of the copper alloy strips ) Is decreased, the hardness A (Hv) of the surface tissue M2 is increased, and the ratio A / B is set to 1.03 or more. If it does in this way, the surface of a copper alloy strip will become harder than the center, and it is described that a fatigue characteristic becomes favorable.

  Patent Document 2 (Japanese Patent No. 5468798) describes a copper alloy material in which the width of a precipitate free zone (PFZ) formed in the vicinity of a grain boundary in a copper alloy during aging treatment is controlled. ing. Since this precipitation-free zone is lower in strength than in the grains, deformation occurs preferentially when bending or repeated stress is applied to the copper alloy, degrading bending workability and fatigue resistance. Based on the knowledge that narrowing the width of this precipitation-free zone can prevent these deteriorations, it has high strength by controlling the particle size of the compound present on the grain boundary and the crystal grain size together. In addition, it is described that a copper alloy sheet having excellent bending workability and excellent fatigue resistance can be obtained.

In Patent Document 3 (Patent No. 5224415), in order to satisfy all of high conductivity, high strength, and good bending workability, the value of the crystal grain size of the Cu—Co—Si based copper alloy is within a predetermined range. The controlled copper alloy material is described. Specifically, it has a composition comprising 0.7 to 2.0% by mass of Co (cobalt) and 0.1 to 0.5% by mass of Si (silicon), and the balance Cu (copper) and inevitable impurities. A copper alloy material for electrical and electronic parts having a mass ratio of Co to Si (Co / Si) of 3 or more and 5 or less, wherein the arithmetic average of the crystal grain size of the base copper alloy is 3 to 20 μm, the standard deviation Is 8 μm or less, the standard deviation is smaller than the arithmetic mean, the particle diameter of the precipitate composed of Co and Si is 5 to 50 nm, and the density of the precipitate is 1 × 10 ⁸ to 1 × 10 ¹⁰ / Mm ² , and the tensile strength as a copper alloy material is 570 MPa or more, and the conductivity is 60% IACS or more.

  Patent Document 4 (Japanese Patent Laid-Open No. 2013-095976) focuses on Cu—Co—Si based alloys as an alloy, and controls not only the crystal orientation but also the work hardening index (n value). It is described that excellent bending workability can be obtained. Specifically, it contains 0.5 to 3.0% by mass of Co and 0.1 to 1.0% by mass of Si, and the balance is made of copper and inevitable impurities. EBSD (Electron Back-Scatter Diffraction: When the electron orientation is analyzed and the crystal orientation is analyzed, the area ratio of the Cube orientation {0 0 1} <1 0 0> is 5% or more, and the Brass orientation {1 1 0} <1 1 2> The area ratio is 20% or less, the Copper azimuth {1 1 2} <1 1 1> is 20% or less, and the work hardening index is 0.2 or less.

JP 2013-067849 A Japanese Patent No. 5468798 Japanese Patent No. 5224415 JP 2013-095976 A

  However, electronic parts are becoming lighter and shorter, and accordingly, bending workability and fatigue characteristics required for metal parts for electronic materials are also increasing. Therefore, there is a demand for a copper alloy sheet material that further improves bending workability and fatigue characteristics while maintaining 0.2% proof stress and conductivity at a high level.

Although the copper alloy strip according to Patent Document 1 is certainly excellent in fatigue characteristics, it is expected that demands for fatigue characteristics will become more stringent in the future, which is not sufficient to cope with this. In addition, no specific proposal has been made regarding the maintenance and improvement of bending workability.
Although the copper alloy sheet according to Patent Document 2 is improved in bending workability and fatigue characteristics, it is considered that the copper alloy sheet material cannot sufficiently cope with a higher strength material when both bending workability and fatigue characteristics are required.
In Patent Document 3 and Patent Document 4, no specific proposal is made regarding the maintenance and improvement of the fatigue properties of copper alloy materials, and there is a possibility that future requirements regarding bending workability may not be sufficiently met. .

The reason why it is difficult to achieve both strength and fatigue characteristics of the copper alloy material is considered as follows.
The fatigue properties of the material improve as the static tensile strength increases. On the other hand, if a stress concentration source exists near the surface layer, the fatigue cracks start from there and the fatigue strength of the material decreases. Micro-defects, precipitates, and microscopic surface irregularities in the material can be a source of such stress concentration. Even when the metal structure is non-uniform, the fatigue strength of the material decreases due to stress concentration at a specific location.
Since a material having high strength is greatly affected by the above-described factors that can become a stress concentration source, it is difficult to effectively improve the fatigue strength only by increasing the static strength of the material. Cu-Co-Si alloys and Cu-Co-Ni-Si alloys have relatively high conductivity, strength, and bending workability, but the high solubility limit temperature of the composition of the second phase particles is high. Solution treatment must be performed, and a non-uniform metal structure is likely to occur. Therefore, in the prior art, a Cu—Co—Si alloy or a Cu—Co—Ni—Si alloy excellent in conductivity, strength, bending workability, and fatigue characteristics could not be obtained.

  The object of the present invention is to solve such problems, and its purpose is to have 0.2% proof stress and conductivity suitable for use in electronic materials, and to provide bending workability and fatigue characteristics. An object is to provide an improved and highly reliable copper alloy for electronic materials.

  As a result of intensive studies, the inventor of the Cu-Co-Ni-Si-based alloy in which a part of Co in the Cu-Co-Si-based alloy is replaced with Ni is measured from EBSD (Electron Back Scatter Diffraction) measurement. By controlling the azimuth difference (KAM value) and the standard deviation between adjacent measurement points obtained, it is possible to improve bending workability and fatigue characteristics while maintaining 0.2% proof stress and conductivity at a high level. I found out that I can do it. And the new knowledge that such control of such KAM value and its standard deviation was realizable by adjusting processing conditions, such as the time of aging treatment, buffing, and strain relief annealing was acquired.

  The present invention contains 0.5 to 3.0 mass% Co, 0.1 to 1.0 mass% Ni, 0.1 to 1.5 mass% Si, and the mass ratio of Ni to Co ( (Ni / Co) is 0.1 to 1.0, (Ni + Co) / Si is 3 to 5 by mass ratio, the balance is made of copper and inevitable impurities, and EBSD (Electron Back Scatter Diffraction: electron backscattering) This is a copper alloy for electronic materials in which the azimuth difference (KAM value) between adjacent measurement points obtained from diffraction) measurement is 1.4 to 2.6, and the standard deviation of the KAM value is 1.2 or less. .

  In the copper alloy for electronic materials according to the present invention, the total of at least one selected from Cr, Zr, Zn, Sn, Mg, Mn, Fe, Ti, Al, P and B is 1.0% by mass or less. Preferably there is.

  Furthermore, this invention also provides the electronic component provided with the copper alloy for electronic materials of this invention.

  It is possible to provide a highly reliable copper alloy for electronic materials having 0.2% proof stress and electrical conductivity suitable for use in electronic materials and having improved bending workability and fatigue characteristics.

FIG. 1 shows a schematic diagram relating to the definition of KAM values.

Hereinafter, embodiments of the present invention will be described in detail.
The copper alloy for electronic materials according to one embodiment of the present invention includes 0.5 to 3.0 mass% Co, 0.1 to 1.0 mass% Ni, and 0.1 to 1.5 mass% Si. The mass ratio of Ni to Co (Ni / Co) is 0.1 to 1.0, the mass ratio is (Ni + Co) / Si is 3 to 5, and the balance is made of copper and inevitable impurities. , The azimuth difference (KAM value) between adjacent measurement points obtained from EBSD (Electron Back Scatter Diffraction) measurement is 1.4 to 2.6, and the standard deviation of the KAM value is 1. 2 or less.

(Addition amount of Co, Ni, Si)
Co, Ni, and Si are precipitated in the parent phase as Co ₂ Si or Ni ₂ Si by performing an appropriate heat treatment, and the strength can be increased without deteriorating the conductivity. However, when the Ni concentration is less than 0.1% by mass, the Co concentration is less than 0.5% by mass, or the Si concentration is less than 0.1% by mass, the precipitation hardening becomes insufficient, and the other component However, the desired strength cannot be obtained even with the addition of. Further, when the Ni concentration exceeds 1.0% by mass, the Co concentration exceeds 3.0% by mass, or the Si concentration exceeds 1.5% by mass, sufficient strength can be obtained. Bending workability and hot workability are reduced.
Preferably, Ni is 0.2 to 0.8 mass%, Co is 1.0 to 2.5 mass%, and Si is 0.3 to 1.0 mass%.

(Concentration ratio of Ni to Co (Ni / Co))
By adjusting Ni / Co, both strength and electrical conductivity are achieved. Increasing the Ni ratio (lowering the Co ratio) increases the strength and decreases the conductivity. On the other hand, when the Co ratio is increased (Ni ratio is decreased), the strength decreases and the conductivity increases. In order to set the 0.2% proof stress in the direction parallel to the rolling direction to 650 MPa or more and the conductivity to 50% IACS or more, Ni / Co is 0.1 to 1.0, preferably 0.2. It is good to adjust so that it may be set to -0.7.

Co, Ni, and Si are (Ni + Co) / Si in a mass ratio of 3 to 5. If it is set as the said ratio, both the intensity | strength and electrical conductivity after precipitation hardening can be improved. When the ratio exceeds 5, the precipitation of Co ₂ Si and Ni ₂ Si in the aging treatment becomes insufficient and the strength is lowered. When the ratio is less than 3, Si that does not precipitate as Co ₂ Si or Ni ₂ Si is solid-solved in the matrix phase and the electrical conductivity is lowered.

(Addition amount of Cr, Zr, Zn, Sn, Mg, Mn, Fe, Ti, Al, P and B)
Cr, Zr, Zn, Sn, Mg, Mn, Fe, Ti, and Al improve the product characteristics such as strength and stress relaxation characteristics without adding a small amount of addition by adding a small amount. 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 addition is exhibited mainly by solid solution in the matrix phase, but further effects can be exhibited by inclusion in the second phase particles. However, if the concentration of Cr, Zr, Zn, Sn, Mg, Mn, Fe, Ti, Al, P, and B exceeds 1.0% by mass in total, bending characteristics and fatigue characteristics are deteriorated and manufacturability is also impaired. Therefore, in this invention, it is preferable to add Cr, Zr, Zn, Sn, Mg, Mn, Fe, Ti, Al, P, and B in total 1.0 mass% or less. The total of Cr, Zr, Zn, Sn, Mg, Mn, Fe, Ti, Al, P and B is more preferably 0.7% by mass or less, and further preferably 0.5% by mass or less. However, since the effect is small if the total of Cr, Zr, Zn, Sn, Mg, Mn, Fe, Ti, Al, P and B is less than 0.01% by mass, Cr, Zr, Zn, Sn, Mg, Mn , Fe, Ti, Al, P and B are preferably 0.01% by mass or more. Moreover, 0.05 mass% or more is more preferable, and 0.1 mass% or more is further more preferable.

(0.2% yield strength)
In order to satisfy characteristics required for a predetermined electronic material such as a connector, the 0.2% proof stress in the rolling parallel direction is preferably 650 MPa or more, more preferably 680 MPa or more. The upper limit value of the 0.2% proof stress is not particularly limited, but is typically 850 MPa or less in order to obtain a conductivity of 50% IACS or more.
The 0.2% proof stress is measured according to JIS Z2241 using a tensile tester.

(conductivity)
The conductivity is preferably 50% IACS or more. Thereby, it can use effectively as an electronic material. The conductivity can be measured by a four-terminal method in accordance with JIS H0505. The conductivity is preferably 55% IACS or more.

(KAM value)
The hexagonal pixel illustrated in FIG. 1 indicates each measurement point of EBSD (Electron Back Scatter Diffraction) measurement, and the KAM value is an azimuth difference between measurement point A and adjacent measurement points 1 to 6. Is defined as the average value of This KAM value has a correlation with the dislocation density, and the higher the KAM value, the greater the change in orientation due to dislocation. As a result of intensive studies by the present inventors, when the KAM value of the material is 1.4 to 2.6 and the standard deviation of the KAM value is 1.2 or less, the 0.2% proof stress is high and the fatigue characteristics, It has been found that bending workability is excellent.
The reason why the standard deviation of the KAM value is in the above range is not intended to limit the present invention by a specific theory. However, when the standard deviation of the KAM value is large, a portion where the distortion is accumulated and the distortion As the fatigue crack propagates starting from these non-uniform strain bands, the fatigue characteristics will be improved by reducing the standard deviation of the KAM value. It is done.
From the above viewpoint, the standard deviation of the KAM value is preferably 1.0 or less, and more preferably 0.9 or less. When the above range is not satisfied, fatigue characteristics and bending workability are deteriorated. The KAM value is preferably 1.5 to 2.5, and more preferably 1.6 to 2.4. When the KAM value is lower than the above range, the 0.2% yield strength decreases. Further, when the KAM value is higher than the above range, the fatigue characteristics and the bending workability are deteriorated.

(Production method)
The Cu—Co—Ni—Si alloy as described above is a process for producing an ingot, a homogenization annealing process, a hot rolling process, a first aging treatment process, an intermediate cold rolling process, a buff polishing process, and a solution treatment. It can manufacture by performing a process, a 2nd aging treatment process, a final cold rolling process, and a strain relief annealing process one by one. In addition, after hot rolling, it is possible to chamfer as necessary. In addition, between the above steps, grinding, polishing, shot blast pickling and the like for removing oxide scale on the surface can be appropriately performed.

  Specifically, first, raw materials such as electrolytic copper, Co, Ni, and Si are melted using an air melting furnace or the like to obtain a molten metal having a desired composition. This molten metal is cast into an ingot. Then, homogenization annealing and hot rolling are performed, the first aging treatment (350 to 450 ° C. for 4 to 8 hours), intermediate cold rolling, buffing, solution treatment, second aging treatment, final cold rolling, Perform strain relief annealing.

Here, in this manufacturing method, it is important to perform the first aging treatment step, buffing and strain relief annealing under predetermined conditions after manufacturing the ingot. In the prior art, the conditions of these processes are not optimized, the characteristics as in the present invention cannot be obtained, and particularly the bending workability and fatigue characteristics are not sufficient.
Hereinafter, the first aging treatment process, the buffing process, and the strain relief annealing process will be described in detail. Note that the other steps can be the conditions normally employed in the manufacturing process of the Cu—Co—Ni—Si alloy.

<Ingot manufacturing>
Melting and casting is generally performed in an atmospheric melting furnace, but can also be performed in a vacuum or in an inert gas atmosphere. After the electrolytic copper is melted, raw materials are added according to the composition of each sample such as Co, Ni, Si, and held for a certain time after stirring to obtain a molten metal having a desired composition. And after adjusting this molten metal to 1250 degreeC or more, it casts to an ingot. In addition to Ni, Co, and Si, at least one selected from Cr, Zr, Zn, Sn, Mg, Mn, Fe, Ti, Al, P, and B is added so that the total amount is 1.0% by mass or less. You can also

<Homogenization annealing>
Coarse crystals are produced during the solidification process during casting, and coarse precipitates are produced during the cooling process. These second phase particles are re-dissolved in the matrix phase by performing hot rolling after performing homogenization annealing at an appropriate temperature and time. When the homogenization annealing temperature is too low, coarse second-phase particles cannot be re-dissolved in the parent phase, and product strength and bending workability are impaired. If the homogenization annealing temperature is too high, the material may be dissolved, which is not preferable. Specifically, the homogenization temperature is preferably 950 to 1025 ° C., and the time is preferably 1 to 24 hours.

<Hot rolling>
The ingot after completion of homogenization annealing is extracted from the furnace and hot rolled. In order to prevent liquid metal embrittlement, it is preferable to start hot rolling in a temperature range of 960 ° C. or lower. Moreover, it is desirable to cool rapidly after hot rolling. When the cooling rate is low, coarse second-phase particles are precipitated. By rapid cooling (= water cooling) to 400 ° C. or less after the hot rolling is completed, precipitation of the second phase particles can be suppressed. Specifically, the cooling rate to 400 ° C. is preferably 15 ° C./sec or more.

<First aging treatment>
By performing the first aging treatment at an appropriate temperature and time after hot rolling, fine Co—Ni—Si particles can be precipitated in the alloy. In the next intermediate cold rolling, more strain is introduced into the alloy in a form trapped by the Co—Ni—Si particles, and uniform recrystallized grains using this strain energy as a driving force later during solution treatment. Is obtained. Under such recrystallized grains, non-uniform strain accumulation is unlikely to occur, so the standard deviation of the KAM value in the product is small. As described above, since the metal structure after solution treatment, and hence the strain distribution of the product, changes depending on the precipitation state of Co-Ni-Si particles before intermediate rolling, it is important to perform the first aging treatment at an appropriate temperature and time. is there. The conditions for the first aging treatment are 350 to 450 ° C. for 4 to 8 hours, more preferably 375 to 425 ° C. for 4 to 8 hours. If this aging treatment is not performed, the standard deviation of the KAM value of the product is increased, and the fatigue characteristics and bending workability are impaired. If the aging treatment temperature is too low or the aging time is too short, the fatigue characteristics and bending workability are similarly impaired. When the aging temperature is too high or the aging time is too long, coarse Co—Ni—Si particles are precipitated in the alloy. These coarse particles cannot be made into a solid solution by the solution treatment described later, and strain cannot be sufficiently accumulated. Therefore, the average KAM value of the product is lowered, and the strength and fatigue characteristics of the product are lowered.
The first aging treatment is preferably performed in an inert atmosphere such as Ar, N ₂ , H ₂ or the like.

<Intermediate cold rolling>
Intermediate cold rolling is performed on the ingot after completion of the first aging treatment. Here, in order to accumulate sufficient work distortion, the workability of intermediate cold rolling is desirably 95% or more.

<Buffing>
By buffing after intermediate cold rolling, a larger amount of processing strain can be accumulated near the surface layer of the material, and uniform recrystallized grain formation during solution treatment can be excited. Further, since the surface roughness of the material is increased by performing the buffing, there is an advantage in that the heating efficiency at the time of the solution treatment is increased. The buffing material used for buffing was a nylon fiber nonwoven fabric containing alumina abrasive grains. The number of the abrasive grains is preferably # 1500 to # 4000. Here, the count of the abrasive grains is determined by a method defined in JIS R6001. Immediately after polishing, wash with water.

<Solution treatment>
The purpose of the solution treatment is to solidify crystallization particles during melt casting and Co—Ni—Si particles precipitated during hot rolling to enhance age hardening ability after the solution treatment. If the temperature is too low, these precipitates cannot be sufficiently dissolved, and a predetermined strength cannot be obtained. If the temperature is too high, the grain boundary pinning effect due to precipitates is lost, the crystal grains become coarse and the strength decreases. In the solution treatment, it is preferable to heat until the copper alloy material before the solution treatment reaches a temperature near the solid solution limit of the second phase particle composition. Specifically, heating is performed at 850 to 1000 ° C. for 0.5 to 10 minutes. Further, from the viewpoint of preventing the precipitation of the second phase particles and the coarsening of the recrystallized grains, the cooling rate after the solution treatment is preferably as fast 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.

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

<Final cold rolling>
By performing the final cold rolling after the aging treatment, dislocation is introduced and the strength is increased. The higher the rolling degree is, the higher the strength of the material is obtained. However, when the rolling degree is too high, a portion having a non-uniform strain distribution is generated, and bending cracks and fatigue fracture tend to progress from a portion having a large strain. In order to obtain a good balance between strength and bending workability, the rolling degree is set to 10 to 50%, preferably 20 to 40%.

<Strain relief annealing>
By performing strain relief annealing, residual stress generated in the material during processing can be removed, and the spring property is improved. The strain relief annealing of the present invention is performed using a continuous annealing furnace. In the case of a batch furnace, since the material is heated in a state of being wound in a coil shape, the material is deformed during the heating and the material is warped, which is not preferable.
The holding temperature during strain relief annealing is 450 to 550 ° C, more preferably 460 to 530 ° C. The holding time is 0.5 to 5 minutes, more preferably 1 to 3 minutes. If the holding temperature is too high, or if the holding time is too long, coarse Co—Ni—Si particles are precipitated, the average KAM value of the product is lowered, and the strength and fatigue characteristics are lowered. If the holding temperature is too low, or if the holding time is too short, bending workability and fatigue characteristics will be reduced.
The rate of temperature rise during strain relief annealing also has a significant effect on material properties. The heating rate is preferably 60 ° C./sec or less, and more preferably 50 ° C./sec or less. When it exceeds 60 ° C./sec, the uneven strain distribution is not eliminated, and the standard deviation of the KAM value of the product is increased, so that the bending workability and the fatigue characteristics are deteriorated. The lower limit of the rate of temperature increase is not particularly limited, but if the rate of temperature increase is too slow, the production efficiency is lowered, and therefore generally 20 ° C./sec or more is preferable.
The furnace tension of the material is 5 to 10 MPa. Under conditions that do not satisfy this range, bending workability and fatigue characteristics may be reduced.
The atmosphere in the furnace is preferably an inert atmosphere such as Ar.

  The Cu—Co—Ni—Si based alloy of the present invention can be processed into various copper products, such as plates, strips, tubes, bars and wires, and this Cu—Co—Ni—Si based copper alloy It can be used for electronic components such as lead frames, connectors, pins, terminals, relays, switches, and foil materials for secondary batteries.

  Next, a copper alloy for electronic materials according to the present invention was prototyped and its performance was confirmed, which will be described below. However, the description here is for illustrative purposes only and is not intended to be limiting.

Copper alloys having the component compositions shown in Table 1 were melted at 1300 ° C. using a high-frequency melting furnace, and cast into 30 mm thick ingots. Next, the ingot was subjected to homogenization annealing at 950 ° C. for 3 hours, and then hot-rolled to a plate thickness of 10 mm and quickly cooled in water. Then, after chamfering to a thickness of 9 mm to remove the scale on the surface, the first aging treatment was performed under the conditions shown in Table 1, and after intermediate cooling rolling, a part of the buffing was performed as shown in Table 1. After the treatment, a solution treatment at 900 ° C. for 5 minutes and a second aging treatment at 500 ° C. for 12 hours were performed, and a plate having a thickness of 0.1 mm was obtained by final cold rolling. Finally, strain relief annealing was performed under the conditions shown in Table 1.
The following characteristics evaluation was performed on each test piece thus obtained. The results are shown in Table 2.

<Strength (0.2% yield strength)>
A JIS No. 13B test piece was prepared so that the tensile direction was parallel to the rolling direction, and a tensile test was performed in parallel with the rolling direction using a tensile tester in accordance with JIS Z2241, and 0.2% yield strength was measured.
<Conductivity>
The test piece was collected so that the longitudinal direction of the test piece was parallel to the rolling direction, and the conductivity (EC:% IACS) was measured by a four-terminal method in accordance with JIS H0505.
<KAM value>
The KAM value was calculated using EBSD (Electron Back Scatter Diffraction) measurement. First, a test piece was cut into a 20 mm square, and the rolled surface was electropolished in a 67% phosphoric acid + 10% sulfuric acid solution at a voltage of 15 V for 60 seconds to reveal a structure. JXA8500F manufactured by JEOL Ltd. was used for the measurement, the rolling surface normal direction (ND: Normal Direction) of the test piece was tilted by 70 ° with respect to the incident electron beam, and the rolling parallel direction (RD: Rolling Direction) was set on the sample holder. It was installed according to the inclination direction, and the focused electron beam was irradiated onto the inclined surface. Acceleration voltage: 20 kV, irradiation current amount: 5 × 10 ⁻⁸ A, working distance 25 mm, measurement with observation field of 200 μm × 200 μm (step width 0.5 μm), n = 5, average value and standard deviation of KAM values Was calculated. The measurement program was TSL OIM data collection, and the analysis program was TSL OIM Analysis.
<Fatigue properties>
According to JIS Z2273, each sample was tested by repeatedly applying a swinging stress of 200 MPa 10 ⁷ times in the direction parallel to the rolling.
<Bending workability>
Since cracks at the time of bending progress from a portion where the strain distribution is not uniform as in the case of fatigue failure, controlling the standard deviation of the KAM value within a specific range is also effective in improving the bending workability. In the present invention, bending workability was evaluated by a 180 ° bending test, assuming bending work under more severe conditions.
180 ° bending workability was evaluated using a test piece cut to a width of 10 mm and a length of 30 mm. After bending about 170 ° in the Badway (bending axis is parallel to the rolling direction) direction with a predetermined bending radius (R) such that R / t = 1.0, the thickness is twice the bending inner radius (R) The both ends of the test piece were pressed and bent at 180 ° and bent. The presence or absence of cracks on the outer surface of the bent portion was visually determined and evaluated according to the following criteria. If evaluation is (circle), bending workability is favorable.
○: No cracks on the outer surface of the bent part are observed ×: Cracks on the outer surface of the bent part are observed

  As shown in Tables 1 and 2, all of Invention Examples 1 to 21 have a suitable 0.2% proof stress and conductivity by performing the first aging treatment step, buffing and strain relief annealing under predetermined conditions. The bending workability and fatigue characteristics could be improved.

In Comparative Example 1, since the first aging treatment was not performed, the standard deviation of the KAM value was out of the predetermined range, and the fatigue characteristics and the bending workability were deteriorated.
In Comparative Example 2, the first aging treatment was performed, but since the temperature was too high, the KAM value was out of the predetermined range, the 0.2% proof stress was lowered, and the fatigue characteristics were deteriorated.
In Comparative Example 3, since the buffing was not performed, the standard deviation of the KAM value was out of the predetermined range, and the fatigue characteristics and the bending workability were deteriorated.
In Comparative Examples 4 to 8, since the strain removing process was not performed under a predetermined condition, the KAM value or the standard deviation of the KAM value was out of the predetermined range, and the fatigue characteristics and the bending workability were deteriorated.
In Comparative Examples 9 to 18, since the amount of the additive element was out of the predetermined range, the required characteristics could not be sufficiently achieved.
Comparative Example 19 was manufactured according to the process described in Patent Document 1, Comparative Example 20 was Patent Document 2, Comparative Example 21 was Patent Document 3, and Comparative Example 22 was manufactured according to the process described in Patent Document 4, both of which were fatigue characteristics and bending. Workability deteriorated.

  As described above, according to the present invention, a highly reliable copper alloy for electronic materials having 0.2% proof stress and electrical conductivity suitable for electronic materials and improved bending workability and fatigue characteristics can be obtained. I understood it.

Claims (3)

  0.5-3.0 mass% Co, 0.1-1.0 mass% Ni, 0.1-1.5 mass% Si, Ni mass ratio to Ni (Ni / Co) Is 0.1 to 1.0, (Ni + Co) / Si is 3 to 5 by mass ratio, the balance is made of copper and inevitable impurities, and from EBSD (Electron Back Scatter Diffraction) measurement. The copper alloy for electronic materials whose azimuth | direction difference (KAM value) between the adjacent measurement points obtained is 1.4-2.6, and the standard deviation of the said KAM value is 1.2 or less.   2. The electronic material according to claim 1, wherein the total of at least one selected from Cr, Zr, Zn, Sn, Mg, Mn, Fe, Ti, Al, P and B is 1.0% by mass or less. Copper alloy.   The electronic component provided with the copper alloy for electronic materials of Claim 1 or 2.