JP2017210674A - Cu-Co-Ni-Si ALLOY FOR ELECTRONIC COMPONENT - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Cu-Co-Ni-Si alloy having improved flexure processability and a manufacturing method therefor.SOLUTION: The Cu-Co-Ni-Si alloy for electronic component contains 0.5 to 3.0 mass% of Co and 0.1 to 1.0 mass% of Ni with a mass ratio of Ni to Co, (Ni/Co), of 0.1 to 1.0 and contains Si with a mass ratio of (Co+Ni)/Si of 3 to 5 and the balance Cu with inevitable impurities and has a percentage of Σ3 coincidence boundaries in all crystal particle boundaries of 30 to 55% and a work hardening coefficient of 0.02 to 0.15.SELECTED DRAWING: None

Description

  The present invention relates to a Cu—Co—Ni—Si alloy for electronic components suitable for electronic components, particularly connectors, battery terminals, jacks, relays, switches, lead frames and the like.

  In recent years, electronic components such as lead frames and connectors used in electric / electronic devices and in-vehicle components have been miniaturized, and the tendency of narrowing the pitch and reducing the height of copper alloy members constituting the electronic components has been remarkable. The smaller the connector, the narrower the pin width and the smaller the folded shape, so that the copper alloy member to be used is required to have strength and bending workability to obtain the necessary spring properties. In addition, from the viewpoint of suppressing heat generation due to an increase in current, it is also required to increase the conductivity of the copper alloy member. In response to such demands, the Cu—Co—Ni—Si alloy has a lower electrical conductivity than the Cu—Ni—Si alloy, but has a higher electrical conductivity, whereas the Cu—Co—Si alloy has a lower electrical conductivity than the Cu—Co—Si alloy. And is excellent in the balance between strength and conductivity, and is used as a signal system terminal member.

  Some members for signal system terminals are subjected to the same bending process as before after thinning the plate thickness by striking both sides of the terminal in advance in order to secure the click feeling at the time of mounting. . In this case, a problem arises in that bending workability is impaired as compared with a state in which no knocking process is added because a processing strain is introduced by adding a knocking process. Therefore, in addition to the balance of strength and electrical conductivity that Cu—Co—Ni—Si alloys have conventionally had, it is a problem to maintain bending workability even when tapping is applied.

  Under such a background, Patent Document 1 describes a technique that achieves good bending workability and repeated bending workability by controlling the twin boundary frequency of a Cu—Co—Si alloy. According to Patent Document 1, after melt casting, homogenization annealing, hot rolling, and face cutting, a plurality of cold rolling and annealing are repeated, and further solution treatment, aging treatment, and final cold rolling are performed. Manufacturing is described. In cold rolling before solution treatment, the average degree of processing of the final pass and the pass one step before the final pass is 32 to 40%, the rolling speed is 220 to 320 mpm, and 850 to 1080 ° C. in the solution treatment. In 5 to 20 seconds.

  In Patent Document 2, the Cu-Co-Si alloy Cube orientation {001} <100>, Brass orientation {110} <112>, Copper orientation {112} <111>, and strength by controlling the work hardening index are disclosed. And a technique for improving the bending workability is described. According to the publication, it is described that the production is performed in the order of casting, hot rolling, cold rolling, pre-annealing, light rolling, solution heat treatment, cold rolling, aging treatment, cold rolling, and strain relief annealing. Yes. It is described that it is effective to adjust the softening rate of pre-annealing and the strain rate of cold rolling.

  Patent Document 3 describes a technique for improving the bending workability by controlling the crystal grain size and its aspect ratio by controlling the cooling rate after solution treatment.

  In Patent Document 4, a tension leveler is used to apply a tension corresponding to 5 to 20% of the 0.2% proof stress (MPa) of a material that has been cold-rolled 15 to 50%. However, by adopting a process in which the elongation rate is continuously repeated at 0.1 to 1.5% and then an aging treatment is adopted, the difference in the amount of precipitates in both the surface layer part and the central part in the thickness direction is obtained. Techniques for generating and improving bending workability are described.

JP 2012-2111377 A JP 2013-95976 A International Publication No. 2009/099198 JP 2007-231364 A

  The strength, conductivity, and bending workability of Cu-Co-Ni-Si alloys have been improved from various viewpoints. On the other hand, downsizing of electronic equipment is also progressing at the same time, and more severe bending workability is achieved. Is required. In addition to notch bending and 180-degree contact bending, a method of taping the material into a tapered shape (thinning the plate thickness) and then bending is also employed. Patent Document 1 describes twin boundary frequency, and Patent Document 2 describes controlling work hardening index, but it is difficult to cope with bending with a striking process by either method. In Patent Documents 3 and 4, it is possible to cope with notch bending and 180-degree contact bending, but it is difficult to cope with bending with tapping.

  Therefore, the main object of the present invention is to improve the bending workability of the Cu—Co—Ni—Si alloy by an approach different from the conventional one. Another object of the present invention is to provide a Cu—Co—Ni—Si alloy that is superior in bending workability to conventional methods.

  As a result of intensive studies to solve the above problems, the present inventor has controlled the twin boundary frequency described in Patent Document 1 and the work hardening index described in Patent Document 2 at the same time, so I thought I could endure it. However, even if the manufacturing processes described in Patent Documents 1 and 2 are simply combined, desired bending workability cannot be obtained. Therefore, it is particularly important to control the twin boundary frequency and work hardening index by a new process. I thought.

  When this point was examined in more detail, it was found that the twin boundary frequency, that is, the ratio of the Σ3-corresponding grain boundary in all the grain boundaries can be controlled by applying a high-temperature heat treatment after hot rolling. Moreover, it discovered that a work hardening index | exponent (n value) was controllable by adding low temperature heat processing before solution treatment. In order to provide bending workability with tapping, it is considered preferable to increase both. However, in the conventional method, if the former is increased, the latter is decreased, and if the latter is increased, the former is decreased. On the other hand, the new knowledge that it was possible to control both with a good balance by the process mentioned above was acquired. The present invention has been completed based on such findings.

  The Cu-Co-Ni-Si alloy for electronic parts of the present invention contains 0.5 to 3.0 mass% Co and 0.1 to 1.0 mass% Ni, and the mass ratio of Ni to Co (Ni / Co) is 0.1 to 1.0, Si is contained so that the mass ratio of (Co + Ni) / Si is 3 to 5, the remainder is made of Cu and inevitable impurities, and all crystal grains The proportion of the Σ3-compatible grain boundary in the boundary is 30 to 55%, and the work hardening index is 0.02 to 0.15.

  The Cu—Co—Ni—Si alloy for electronic parts of the present invention further includes at least one selected from the group consisting of Fe, Mg, Sn, Zn, B, P, Cr, Zr, Ti, Al, and Mn in total. It can contain 1.0 mass%.

  The Cu—Co—Ni—Si alloy for electronic parts of the present invention preferably has a 0.2% proof stress in a direction parallel to the rolling direction of 650 MPa or more and a conductivity of 50% IACS or more.

  In the Cu-Co-Ni-Si alloy for electronic parts of the present invention, the bending axis after rolling at a workability of 20% / plate thickness (t) = 1.0, and the bending axis is the same as the rolling direction. It is preferable that the average roughness Ra of the surface of the bent portion when the W-bending test is performed with the Badway is 1.0 μm or less.

  The manufacturing method of the Cu-Co-Ni-Si alloy for electronic components of this invention contains 0.5-3.0 mass% Co and 0.1-1.0 mass% Ni, Ni with respect to Co Concentration (mass%) ratio of Ni (Co / Ni) is 0.1 to 1.0, Si is contained so that the mass ratio of (Co + Ni) / Si is 3 to 5, with the balance being Cu and inevitable A step of casting an ingot of a Cu—Co—Ni—Si alloy made of impurities, a step of homogenizing annealing, a step of hot rolling, and a first heat treatment at 900 to 950 ° C. for 3 to 24 hours A step, a step of performing cold rolling at a workability of 90% or more, a step of applying a second heat treatment at 400 to 600 ° C. for 1 to 10 hours, a step of applying a solution treatment, a step of applying an aging treatment, And performing the final cold rolling process in this order. .

  In the method for producing a Cu—Co—Ni—Si alloy for electronic parts according to the present invention, the Cu—Co—Ni—Si alloy further comprises Fe, Mg, Sn, Zn, B, P, Cr, Zr, Ti, Al and A total of at least one selected from the group consisting of Mn can be up to 1.0% by mass.

  The copper-strengthened product of the present invention comprises any one of the above-described Cu—Co—Ni—Si alloys.

  An electronic component according to the present invention includes any one of the above-described Cu—Co—Ni—Si alloys.

  According to the present invention, it is possible to obtain a Cu—Co—Ni—Si alloy excellent in the three characteristics of strength, conductivity, and bending workability. Such a copper alloy can be particularly suitably used for electronic parts such as connectors and battery terminals that are manufactured by bending after tapping, and can contribute to improving the reliability of these electronic parts.

(Co concentration)
Co has the effect of improving the strength and conductivity of the copper alloy sheet by forming a Co—Ni—Si based precipitate together with Ni and Si described later. When the Co content is too small, it becomes difficult to sufficiently exhibit this effect. Therefore, the Co content is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and even more preferably 1.1% by mass or more. On the other hand, since the melting point of Co is higher than that of Ni, if the Co content is too large, complete solid solution is difficult, and the undissolved portion does not contribute to the strength. Therefore, the Co content is preferably 3.0% by mass or less, and more preferably 2.0% by mass or less.

(Ni concentration)
Ni, together with Co and Si, forms a Co—Ni—Si based precipitate and has the effect of improving the strength and conductivity of the copper alloy sheet. When the Ni content is too small, it becomes difficult to sufficiently exhibit this effect. Therefore, the Ni content is 0.1% by mass or more, preferably 0.2% by mass or more, and more preferably 0.3% by mass or more. On the other hand, if the Ni content is too large, not only the strength improvement effect is saturated, but also the conductivity is lowered. In addition, coarse precipitates are easily generated and cause cracks during bending. Therefore, the Ni content is 1.0% by mass or less, and more preferably 0.8% by mass or less.

(Si concentration)
Si produces Co—Ni—Si based precipitates together with Ni and Co. However, Ni, Co, and Si in the alloy are not necessarily all precipitated by the aging treatment, and to some extent exist in a solid solution state in the Cu matrix. Ni, Co, and Si in the solid solution state slightly improve the strength of the copper alloy sheet, but the effect is smaller than that in the precipitated state, and causes a decrease in conductivity. Therefore, in general, the Si content is preferably as close to the composition ratio of precipitates (Ni + Co) ₂ Si as possible. That is, it is common to adjust the (Ni + Co) / Si mass ratio within a range of 3 to 5 centering around 4.2, and Si has a (Ni + Co) / Si mass ratio within this range. Add as follows. The mass ratio of (Ni + Co) / Si is preferably 3.7 to 4.7.

(Mass 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.

(Additive elements)
If necessary, at least one of Fe, Mg, Sn, Zn, B, P, Cr, Zr, Ti, Al, and Mn may be added. For example, Sn and Mg have the effect of improving the stress relaxation resistance, Zn has the effect of improving the solderability and castability of the copper alloy sheet, and Fe, Cr, Mn, Ti, Zr, Al, etc. have the strength. Has the effect of improving. In addition, P has a deoxidizing effect, B has an effect of refining a cast structure, and has an effect of improving hot workability. However, if the amount of these additive elements is too large, the productivity and conductivity are greatly impaired. Therefore, the additive elements can be 0 to 1.0% by mass in total. In consideration of the balance of strength, electrical conductivity, and bendability, it is preferable to contain one or more of the above elements in a total amount of 0.1 to 0.7% by mass.

  In addition, for each additive element, in consideration of the balance of stress relaxation resistance, strength, solderability, castability, hot workability, etc., Zn is 0.1 mass within a range not exceeding the total amount. % And 1.0 mass% or less, Sn and Cr can be contained 0.1 mass% or more and 0.8 mass% or less, Fe, Mg and Mn are 0.1 mass% or more And 0.5 mass% or less can be contained, B, P, Zr, Ti, and Al can be contained 0.01 mass% or more and 0.2 mass% or less.

(Percentage of grain boundaries corresponding to Σ3 in all grain boundaries)
According to the corresponding grain boundary theory, the Σ3 corresponding grain boundary refers to the twin boundary. Because twin boundaries have good atomic alignment between the boundaries, non-uniform deformation is unlikely to occur near the boundaries, and cracks and wrinkles starting from the boundaries are less likely to occur during bending deformation. Workability is improved.

  The ratio of the Σ3 corresponding grain boundary to the total crystal grain boundary can be measured by an EBSD (Electron Back Scatter Diffraction Pattern) method. More specifically, after analyzing the crystal orientation by the EBSD method, the orientation difference between adjacent crystal orientations can be obtained, and the ratio (grain boundary character distribution) of random grain boundaries and corresponding grain boundaries can be determined. The ratio of the Σ3-corresponding grain boundary in all the grain boundaries can be calculated by (total length of corresponding grain boundaries Σ3) / (total sum of crystal grain lengths) × 100.

  In the present invention, in the crystal orientation analysis in the EBSD measurement with respect to the material surface (rolled surface), the ratio of the Σ3-corresponding grain boundary in all the grain boundaries is 30 to 55%. In both cases where this ratio is less than 30% and more than 55%, the bendability after the hitting process is deteriorated. From this viewpoint, the proportion is preferably 35 to 50%, and more preferably 40 to 50%.

  In the measurement of the ratio of the Σ3-compatible grain boundary in the total grain boundary, for the stability of the measurement result, five fields of 400 μm × 400 μm per field are measured, and each field occupies all the grain boundaries. The ratio of the grain boundary corresponding to Σ3 is obtained, and the average value of the five fields of view is calculated as the measured value.

As measurement conditions in the EBSD measurement, the following can be employed.
(A) SEM conditions ・ Beam conditions: acceleration voltage 15 kV, irradiation current amount 5 × 10 ⁻⁸ A
・ Work distance: 25mm
Observation field: 400 μm × 400 μm
・ Observation surface: Rolling surface ・ Pretreatment of observation surface: Electropolishing in a solution of phosphoric acid 67% + sulfuric acid 10% + water under conditions of 15 V × 60 seconds (b) EBSD conditions ・ Measurement program : OIM Data Collection
Data analysis program: OIM Analysis (Ver. 5.3)
・ Step width: 0.5μm

(Work hardening index (n value))
When a test piece is pulled and a load is applied in a tensile test, each part of the test piece is uniformly extended (uniform elongation) in the plastic deformation region exceeding the elastic limit and reaching the maximum load point. In the plastic deformation region where the uniform elongation occurs, the relationship of the following formula (1) is established between the true stress σ _t and the true strain ε _t , which is called the n-th power hardening law.
σ _t = Kε _t ⁿ (1)
Here, in formula (1), n is referred to as a work hardening index (Kazuto Sudo, material test method, Uchida Otsuru Farm Co., (1976), p. 34), and takes a value of 0 ≦ n ≦ 1. . The higher the work hardening index, the better the bending workability.

In a material satisfying the n-th power hardening law, the true strain at the highest load point of the stress-strain curve matches the work hardening coefficient. Therefore, in the present invention, the true strain at the highest load point is expressed by the work hardening index (n value). (Kazuto Sudo, “Materials Testing Method”, Uchida Otsuru Farm, 1976, p. 35). Specifically, a tensile test in the rolling parallel direction is performed according to JIS Z2241 (2011) by the same method as measuring 0.2% proof stress described later, and a stress-strain curve is obtained. The true strain ε _t is calculated by substituting the nominal strain ε at the highest load point read from the obtained stress-strain curve into the following equation (2).
ε _t = ln (1 + ε) (2)

  In obtaining a Cu—Co—Ni—Si alloy excellent in strength, electrical conductivity and bending workability, the ratio of Σ3 corresponding grain boundaries in the total grain boundaries is controlled and the n value is set within a predetermined range. is important. Specifically, the work hardening index (n value) in a direction parallel to the rolling direction is 0.02 to 0.15. n value becomes like this. Preferably it is 0.05-0.14, More preferably, it is 0.08-0.13.

(0.2% yield strength)
The 0.2% yield strength in the direction parallel to the rolling direction is measured according to JIS Z2241 (2011) (metal material tensile test method). In the Cu—Co—Ni—Si alloy according to the present invention, in one embodiment, the 0.2% proof stress in the direction parallel to the rolling direction can achieve 650 MPa or more. Preferably it is 700 MPa or more, More preferably, it is 750 MPa or more. The upper limit value of the 0.2% proof stress is not particularly limited, but is 850 MPa or less, and typically 800 MPa or less in order to obtain a conductivity of 50% IACS or more.

(conductivity)
Measured by the 4-terminal method in accordance with JIS H0505. In one embodiment, the Cu—Co—Ni—Si alloy according to the present invention can achieve a conductivity of 50% IACS or more. Preferably it is 55% IACS or more, More preferably, it is 60% IACS or more. The upper limit value of the electrical conductivity is not particularly limited, but is 70% IACS or less, and typically 65% IACS or less to achieve a 0.2% proof stress of 650 MPa or more.

(Bending workability)
The Cu—Co—Ni—Si alloy according to the present invention can have excellent bending workability. In one embodiment of the Cu—Co—Ni—Si alloy according to the present invention, after applying 20% rolling simulating the tapping process, according to JIS H3130 (2012), the W bend test is performed with a bend radius (R ) / Plate thickness (t) = 1.0, the average roughness Ra on the outer peripheral surface of the bent portion is 1.0 μm or less. The average roughness Ra is calculated according to JIS B0601 (2013). The fact that the average roughness Ra of the bent part is small even after the bending process means that harmful cracks that may cause breakage are unlikely to enter the bent part. Generally, the average roughness Ra of the surface of the Cu—Co—Ni—Si alloy according to the present invention before the bending test is 0.2 μm or less.
From the viewpoint of preventing the occurrence of cracks described above, the surface roughness of the bent portion is preferably 0.8 μm or less, and more preferably 0.6 μm or less. On the other hand, there is no particularly preferred lower limit, but the surface roughness of the bent portion is typically 0.1 μm or more, more typically 0.2 μm or more.

(Use)
The Cu-Co-Ni-Si alloy according to the present invention can be processed into various copper products, such as plates, strips, tubes, bars and wires. The Cu—Co—Ni—Si alloy according to the present invention is preferably used for a conductive material and a spring material in electronic parts such as a switch, a connector, a jack, a terminal (particularly a battery terminal), and a relay, although not limited thereto. be able to. These electronic components can be used, for example, as vehicle-mounted components or components for electric / electronic devices.

(Production method)
The example of the suitable manufacturing method of the Cu-Co-Ni-Si alloy which concerns on this invention is demonstrated for every process.

<Ingot casting>
Using an atmospheric melting furnace, raw materials such as electrolytic copper, Ni, Co, and Si are melted to obtain a molten metal having a desired composition as described above. Then, this molten metal is cast into an ingot. The additive elements other than Ni, Co, and Si are one or two or more selected from the group consisting of Fe, Mg, Sn, Zn, B, P, Cr, Zr, Ti, Al, and Mn. Add to contain 0% by weight.

<Homogenization annealing and hot rolling>
Since the solidified segregation and crystallized matter produced during the production of the ingot are coarse, it is desirable to make it as small as possible by dissolving it in the parent phase as much as possible by homogenization annealing. This is because it is effective in preventing bending cracks. Specifically, after ingot casting, it is preferable to perform hot rolling after heating to 900 to 1050 ° C. and performing homogenization annealing for 3 to 24 hours. In hot rolling, it is preferable that the pass from the original thickness to the overall reduction rate of 90% is 700 ° C. or higher. Thereafter, it is rapidly cooled to room temperature with water cooling.

<First heat treatment>
After the hot rolling, a first heat treatment is performed at a high temperature. By re-dissolving coarse precipitates precipitated during hot rolling, the stacking fault energy can be reduced, and the proportion of Σ3-corresponding grain boundaries in the solution treatment described later can be increased. The conditions for the first heat treatment are typically 900 to 950 ° C. for 3 hours to 24 hours, preferably 900 ° C. to 950 ° C. for 7 hours to 20 hours, more preferably 910 hours to 940 ° C. for 7 hours to 20 hours. Time and heat-cool after heating. If this step is not carried out, the proportion of the Σ3-compatible grain boundaries in the total grain boundaries will be small even if the solution treatment and the subsequent steps are carried out appropriately. Moreover, even if it performs 1st heat processing at less than 900 degreeC, it becomes small similarly. On the other hand, when the first heat treatment is performed at a temperature exceeding 950 ° C., the ratio of the grain boundary corresponding to Σ3 increases, but the crystal grain size increases, so that the bending workability decreases.

<Cold rolling and second heat treatment>
After the first heat treatment, cold rolling is performed under a condition of a workability (rolling rate) of 90% or more, preferably 93% or more, and then a second heat treatment is performed at a low temperature. Although the mechanism has not been elucidated, by adding a low-temperature second heat treatment here, the work hardening index can be increased while maintaining the proportion of the grain boundaries corresponding to Σ3 in the total grain boundaries. The conditions for the second heat treatment are typically 400 to 600 ° C. for 1 hour to 10 hours, preferably 450 to 550 ° C. for 1 hour to 10 hours, more preferably 450 to 550 ° C. for 3 hours to 8 hours, Cool with water after heating. If this step is not carried out, the work hardening index becomes small even if the solution treatment and the subsequent steps are carried out appropriately. Moreover, it becomes small similarly, when not performing 2nd heat processing on appropriate conditions. The work hardening index is also reduced when the degree of cold rolling work before the second heat treatment is too small. The degree of processing (%) is defined by {((thickness before rolling−thickness after rolling) / thickness before rolling) × 100}.

<Solution treatment>
Thereafter, a solution treatment is performed. Specifically, it is heated to 900 to 1050 ° C., heated for 30 seconds to 10 minutes, and cooled with water after heating.

<Aging treatment>
An aging treatment is performed following the solution treatment. Heating at a material temperature of 450 to 600 ° C. for 5 to 25 hours is preferable, and heating at a material temperature of 480 to 570 ° C. for 10 to 20 hours is more preferable. The 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>
Following the aging treatment, the final cold rolling is performed. Although the strength can be increased by the final cold working, in order to obtain a good balance between strength and bending workability as intended in the present invention, the rolling reduction is 5 to 40%, preferably 10 to 35%. Is desirable.

<Strain relief annealing>
Following the final cold rolling, strain relief annealing is performed. Heating is preferably performed at a material temperature of 350 to 650 ° C. for 1 second to 3600 seconds, a material temperature of 350 to 450 ° C. for 1500 seconds to 3600 seconds, a material temperature of 450 to 550 ° C. for 500 seconds to 1500 seconds, a material temperature of 550 to 650 It is more preferable to heat at 1 ° C. for 1 second to 500 seconds.

  A person skilled in the art will understand that steps such as grinding, polishing, and shot blast pickling for removing oxide scale on the surface can be appropriately performed between the above steps.

  Examples of the present invention are shown below together with comparative examples, which are provided for a better understanding of the present invention and its advantages, and are not intended to limit the invention.

  A copper alloy containing each element shown in Table 1 and the balance consisting of copper and impurities was melted at 1300 ° C. in a high frequency melting furnace and cast into a 30 mm thick ingot. Next, the ingot was heated at 1000 ° C. for 5 hours, and then hot-rolled to a thickness of 1 to 10 mm, and cooled quickly after the hot rolling was completed. Next, the first heat treatment was performed under the conditions shown in Table 1 and immediately cooled with water. Thereafter, cold rolling shown in Table 1 was performed to obtain a plate having a thickness of 0.125 mm. Next, the second heat treatment and solution treatment under the conditions shown in Table 1 were performed. Thereafter, the plate thickness was set to 0.1 mm by aging treatment at 500 ° C. for 15 hours and rolling at a workability of 20%, and strain relief annealing was performed at 450 ° C. for 1500 seconds.

The following evaluation was performed about the produced test piece.
(A) Ratio of grain boundary corresponding to Σ3 in all crystal grain boundaries After electrolytic polishing of the plate surface (rolled surface) of each test piece, EBSD measurement was performed. The total grain boundary length and the length of the grain boundary corresponding to Σ3 were determined, and the ratio was calculated.
(B) Work hardening index (n value)
A tensile test in a direction parallel to the rolling direction was performed to obtain a stress-strain curve, and the n value was obtained by the method described above.
(C) 0.2% yield strength A JIS No. 13B test piece was prepared, and 0.2% yield strength in a direction parallel to the rolling direction was measured using a tensile tester according to the measurement method described above.
(D) Conductivity Conductivity (EC:% IACS) was measured by the 4-terminal method in accordance with JIS H0505.
(E) Surface roughness of the bent part after rolling at a working degree of 20% After rolling each test piece at a working degree of 20% (plate thickness of 0.08 mm) simulating a test piece, in accordance with JIS H3130 (2012). A W bending test was performed with Badway (bending axis being in the same direction as the rolling direction) and R / t = 1.0, and the outer peripheral surface of the bent portion of the test piece was observed. As an observation method, the outer peripheral surface of the bent portion was photographed using a laser tech confocal microscope HD100, and the average roughness Ra (conforming to JIS B0601: 2013) was measured using the attached software and compared. In addition, when the sample surface before a bending process was observed using the confocal microscope, the unevenness | corrugation was not able to be confirmed but all average roughness Ra was 0.2 micrometer or less. 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 “×”.

  As shown in Tables 1 and 2, each of Invention Examples 1 to 20 contains each element in a predetermined amount and is manufactured under conditions satisfying a predetermined range, so that the Σ3 corresponding grain boundary occupying in all the crystal grain boundaries can be obtained. The ratio was 30 to 55%, the work hardening index was 0.02 to 0.15, and 0.2% proof stress, conductivity, and bending workability were good.

On the other hand, in Comparative Examples 1 to 3, when the temperature condition of the first heat treatment is out of the predetermined range, or the first heat treatment is not performed, the ratio of the Σ3-compatible grain boundaries does not fall within the predetermined range. As a result, bending workability deteriorated.
Comparative Example 4 had a small degree of cold rolling after the first heat treatment, Comparative Examples 5 and 6 performed the second heat treatment under temperature conditions outside the predetermined range, and Comparative Example 7 did not perform the second heat treatment. As a result, in any of Comparative Examples 4 to 7, the work hardening index decreased and the bending workability deteriorated.

  In Comparative Examples 8 and 9, due to the Co content, the strength in Comparative Example 8 and the conductivity and bending workability in Comparative Example 9 deteriorated.

In Comparative Examples 10 and 11, due to the Ni content, the bending workability in Comparative Example 10 and the conductivity and bending workability in Comparative Example 11 deteriorated. In Comparative Examples 12 and 13, since the Ni / Co ratio was outside the predetermined range, the strength or the conductivity decreased. In Comparative Examples 14 and 15, the ratio of (Co + Ni) / Si was too small or too large, resulting in a decrease in strength or conductivity. In Comparative Example 16, the conductivity was lowered by adding the additive element in excess of the predetermined amount.
Comparative Example 17 was manufactured according to the steps described in Patent Document 1, Comparative Example 18 was Patent Document 2, Comparative Example 19 was Patent Document 3, and Comparative Example 20 was described in Patent Document 4, but the bending workability deteriorated. .

Claims (8)

  0.5 to 3.0% by mass of Co and 0.1 to 1.0% by mass of Ni, and the mass ratio of Ni to Co (Ni / Co) is 0.1 to 1.0, Si is contained so that the mass ratio of (Co + Ni) / Si is 3 to 5, the balance is made of Cu and inevitable impurities, and the proportion of Σ3 corresponding grain boundaries in the total grain boundaries is 30 to 55%. And the Cu-Co-Ni-Si alloy for electronic components whose work hardening index is 0.02-0.15.   Furthermore, Cu-Co of Claim 1 which contains at least 1 type chosen from the group which consists of Fe, Mg, Sn, Zn, B, P, Cr, Zr, Ti, Al, and Mn in total up to 1.0 mass%. -Ni-Si alloy.   The Cu-Co-Ni-Si alloy according to claim 1 or 2, wherein the 0.2% yield strength in a direction parallel to the rolling direction is 650 MPa or more, and the electrical conductivity is 50% IACS or more.   Bending radius (R) / sheet thickness (t) after rolling at a workability of 20% = 1.0, and the average roughness of the surface of the bending portion when a W-bending test is performed with a Badway in which the bending axis is the same as the rolling direction. Ra is 1.0 micrometer or less, The Cu-Co-Ni-Si alloy as described in any one of Claims 1-3.   It contains 0.5 to 3.0% by mass of Co and 0.1 to 1.0% by mass of Ni, and the concentration ratio (Ni / Co) of Ni to Co is 0.1 to 1. A step of casting an ingot of a Cu—Co—Ni—Si alloy containing 0 and Si such that the mass ratio of (Co + Ni) / Si is 3 to 5 and the balance being Cu and inevitable impurities; A step of performing homogenization annealing, a step of performing hot rolling, a step of performing a first heat treatment at 900 to 950 ° C. for 3 to 24 hours, a step of performing cold rolling with a workability of 90% or more, and 400 to 400 An electronic component comprising performing a second heat treatment at 600 ° C. for 1 to 10 hours, a solution treatment step, an aging treatment step, and a final cold rolling step in this order. For producing Cu-Co-Ni-Si alloy for use.   The Cu-Co-Ni-Si alloy further contains at least one selected from the group consisting of Fe, Mg, Sn, Zn, B, P, Cr, Zr, Ti, Al, and Mn in a total of up to 1.0 mass% The method for producing a Cu—Co—Ni—Si alloy according to claim 5.   The copper-stretched article provided with the Cu-Co-Ni-Si alloy as described in any one of Claims 1-4.   The electronic component provided with the Cu-Co-Ni-Si alloy as described in any one of Claims 1-4.