JP6730784B2 - Cu-Ni-Co-Si alloy for electronic parts - Google Patents

Description

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

Conventionally, copper-based materials such as phosphor bronze, red copper, and brass, which are excellent in electrical conductivity and thermal conductivity, have been widely used as materials for electric and electronic devices in general. In recent years, there has been an increasing demand for miniaturization, weight reduction, and high functionality of electric/electronic devices, and high density packaging accompanying this, and copper-based materials applied to these are also required to have various characteristics.

With the miniaturization of parts, the material is becoming thinner, and it is required to improve the material strength. In applications such as relays, the demand for fatigue characteristics is increasing, and it is necessary to improve strength. In addition, as the size of parts is reduced, the conditions for bending are becoming stricter, and it is required to have high strength and excellent bending workability.

In Patent Document 1, in particular, 0.2% proof stress has a very high strength of 980 MPa or more, or 1000 MPa or more, and has a conductivity of 30% IACS or more, more preferably 34% or more, and stress relaxation resistance and A Cu-Ni-Co-Si-based copper alloy sheet material having good press workability has been proposed. According to Patent Document 1, this copper alloy sheet is used for heat treatment 1 for heating and holding a slab at a high temperature, hot rolling, cold rolling, solution heat treatment, and for promoting precipitation of a Co—Si compound during aging. It is manufactured through a heat treatment 2 that imparts a heat history including a pretreatment heat treatment, and an aging treatment performed in a low temperature range.

JP, 2014-156623, A JP, 2011-231393, A JP, 2009-007666, A

By the way, according to Patent Document 1, it is described that in a Cu—Ni—Co—Si alloy, a precipitate is formed by two kinds of compounds, a Ni—Si compound and a Co—Si compound, depending on the aging temperature. Therefore, it is presumed that the influence of precipitates on dislocations varies with the composition. That is, it is considered that the amount of dislocation introduced depends on the composition of the precipitate. Since the dislocations become non-uniform, stress during bending may be concentrated and bending workability may be impaired.

Therefore, in Patent Document 2, for example, bending workability can be improved by increasing the ratio of crystal grains having {100} orientation (Cube orientation) with less anisotropy, and at the same time, bending anisotropy of bending workability can be improved. It is stated that it can be remarkably improved. Specifically, a melting/casting step of melting and casting the copper alloy raw material, a hot rolling step performed after this melting/casting step, and a hot rolling step after this hot rolling step The first cold rolling step of performing cold rolling at a rolling rate of 70% or more, the intermediate annealing step of performing heat treatment at a heating temperature of 500 to 650° C. after the first cold rolling step, and the intermediate annealing step of A second cold rolling step in which cold rolling is performed at a rolling rate of 70% or more, a solution treatment step in which a solution treatment is performed after the second cold rolling step, and 400 after the solution treatment step. It is realized by a method including an aging treatment step of performing aging treatment at ˜500° C.

Further, for example, in Patent Document 3, the diffraction intensity from the {111} plane on the plate surface is I{111}, the diffraction intensity from the {200} plane is I{200}, and the diffraction intensity from the {220} plane is I{. 220}, the diffraction intensity from the {311} plane is I{311}, and the ratio of the diffraction intensity from the {200} plane among these diffraction intensities is R{200}=I{200}/(I{111} +I{200}+I{220}+I{311}), a technique for improving bending workability by setting R{200} to a certain value or more is described. Specifically, in the final recrystallization heat treatment, This has been achieved by introducing intermediate annealing to the extent that the processed structure does not completely recrystallize, and in addition, intermediate rolling.

In the future, Corson copper alloys will be required to have high strength and high conductivity as well as bendability, and it is generally difficult to achieve both strength and bendability, leaving room for improvement from the viewpoint of improving reliability. There is.

As a result of diligent research by the present inventors, in the Cu—Ni—Co—Si alloy, if the compositions of the precipitates can be made uniform, dislocations will be uniform and the stress during bending will be dispersed, From the viewpoint that improvement of bending workability is expected, optimum solution heat treatment conditions have been found, and the present invention has been completed.

That is, the present invention is
(1) It contains 3.0 to 4.5% by mass of Ni and 0.1 to 1.0% by mass of Co, and the concentration (% by mass) ratio of Ni to Co (Ni/Co) is 3.5. At least 100 second-phase particles, the content of which is adjusted to be about 30 and which contains Si so that the (Ni+Co)/Si mass ratio is from 3 to 5 and the balance is Cu and inevitable impurities. A Cu-Ni-Co-Si alloy for electronic parts, in which the coefficient of variation of the concentration ratio of Ni to Co (Ni/Co) measured with respect to Co is 20% or less.
(2) Further, at least one selected from the group consisting of Fe, Mg, Sn, Zn, B, P, Cr, Zr, Ti, Al and Mn is contained at a maximum of 2.5% by mass in total, and the composition is described in (1). alloy.
(3) The alloy according to (1) or (2), wherein the average number of second-phase particles having a particle size of 5 to 30 nm is 0.5×10 ⁹ particles/mm ² or more.
(4) The alloy according to any one of (1) to (3), which has a 0.2% proof stress in a direction parallel to the rolling direction of 900 MPa or more and an electric conductivity of 30% IACS or more.
(5) When the bending radius (R)/thickness (t)=1.0 and the W-bending test is performed in Badway (the bending axis is in the same direction as the rolling direction), the average roughness Ra of the bent portion surface is 1.0 μm or less. The alloy according to any one of (1) to (4).
(6)-Step 1 of melting and casting an ingot of a copper alloy having the composition according to (1) or (2),
Step 2 of performing hot rolling after heating at −900° C. or more and 1050° C. or less and quenching to room temperature, and −900° C. or more and 1050° C. or less for 30 seconds while applying tension of 1 MPa or more and 10 MPa or less after cold rolling. A step 3 in which a solution treatment is performed by heating for 10 minutes, and a heating rate and a cooling rate in a temperature range between 600° C. and 700° C. before and after the solution treatment are 50° C./second or more;
-Aging treatment step 4 in which the material temperature is heated to 400 to 550°C;
A method for producing a copper alloy, which comprises performing the steps in order.
(7) An electronic component including the alloy according to any one of (1) to (5).

According to the present invention, in addition to high strength and high conductivity, Corson copper alloy, Cu-Ni-Co-Si alloy for electronic parts with improved reliability, which is also provided with bendability that is generally difficult to balance strength, is provided. Provided.

Hereinafter, an embodiment of a Cu-Ni-Co-Si alloy for electronic parts according to the present invention will be described. In the present invention,% means mass% unless otherwise specified.

(1) Composition of Base Material First, the alloy composition will be described. The copper alloy of the present invention is a Cu-Ni-Co-Si alloy. In addition, in the present specification, a copper alloy in which other alloying elements such as Fe, Mg, Sn, Zn, B, P, Cr, Zr, Ti, Al and Mn are added to the basic component of Cu—Ni—Co—Si. Is also collectively referred to as a Cu-Ni-Co-Si alloy.

Ni has the effect of forming Ni-Co-Si based precipitates together with Co and Si described later, and improving the strength and conductivity of the copper alloy sheet. If the Ni content is too small, it is difficult to sufficiently exert this effect. Therefore, the Ni content is preferably 3.0% by mass or more, more preferably 3.2% by mass or more, and further preferably 3.4% by mass or more. On the other hand, when the Ni content is too large, the strength improving effect is saturated and the conductivity is lowered. In addition, coarse precipitates are easily generated, which causes cracks during bending. Therefore, the Ni content is preferably 4.5% by mass or less, and more preferably 4.1% by mass or less.

Co forms an Ni-Co-Si based precipitate together with Ni and Si, and has the effect of improving the strength and conductivity of the copper alloy sheet material. If the Co content is too small, it is difficult to exert this effect sufficiently. Therefore, the Co content is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and further preferably 0.3% 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, it is difficult to form a complete solid solution, and the undissolved portion does not contribute to the strength. Therefore, the Co content is preferably 1.0% by mass or less, and more preferably 0.8% by mass or less.

Further, the present invention is characterized in that Ni-Co-Si based precipitates are generated to exert the effect of improving the strength and conductivity of the copper alloy sheet at a higher level. Therefore, unlike the case of producing a normal Co-Si-based precipitate and a Ni-Si-based precipitate, the coefficient of variation of the concentration ratio of Ni to Co (Ni/Co) is reduced to some extent in the composition of each precipitate. Required to do so. From this viewpoint, the variation coefficient of the concentration ratio of Ni to Co (Ni/Co), that is, “standard deviation/average value×100” is set to 20% or less, preferably 16% or less. The coefficient of variation of Ni/Co is a value that can be measured and estimated for 100 or more second phase particles that are precipitates.
Further, in order to keep the coefficient of variation of the Ni/Co concentration ratio in such a precipitate at a predetermined value or less, the Ni/Co concentration (mass %) ratio in the alloy material before the precipitation of the second phase particles is 3.5. It is good to adjust so as to be -30, preferably 5-15.

Si produces Ni-Co-Si based precipitates together with Ni and Co. However, Ni, Co, and Si in the alloy do not all become precipitates by the aging treatment, and exist to some extent 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 material, but their effect is smaller than that in the precipitated state, and they also become a factor to lower the conductivity. Therefore, it is generally preferable that the Si content be as close as possible to the composition ratio of the precipitate (Ni+Co) ₂ Si. That is, the (Ni+Co)/Si mass ratio is generally adjusted to 3 to 5 with a center of about 4.2, and Si is added so that the (Ni+Co)/Si mass ratio falls within this range. ..

If necessary, Fe, Mg, Sn, Zn, B, P, Cr, Zr, Ti, Al, Mn and the like may be added to the copper alloy sheet material of the present invention. For example, Sn and Mg have the effect of improving the stress relaxation resistance property, Zn have the effect of improving the solderability and castability of the copper alloy sheet material, and Fe, Cr, Mn, Ti, Zr, Al, etc. Has the effect of improving. In addition, P has a deoxidizing effect, B has a refining effect of the cast structure, and has an effect of improving hot workability. However, if the amount of these additional elements is too large, the productivity is greatly impaired. Therefore, 0 to 2.5 mass% can be contained in total. Further, considering the balance of strength, conductivity, and bendability, it is preferable to contain one or more of the above elements in a total amount of 0.2 to 1.0 mass %. In addition, in consideration of the balance of stress relaxation resistance, strength, solderability, castability, hot workability, etc., for each additive element, Zn is 0.1 mass in a range not exceeding the total amount. % Or more and 2.0 mass% or less, Sn and Cr can be contained in 0.1 mass% or more and 1.0 mass% or less, and Fe, Mg, and Mn are 0.1 mass% or more and 0.1 mass% or more. 5 mass% or less can be contained, and B, P, Zr, Ti and Al can be contained by 0.01 mass% or more and 0.3 mass% or less.

(2) Strength and Electric Conductivity The alloy of the present invention has high strength and high electric conductivity, and is suitable for electronic parts, particularly connectors, battery terminals, jacks, relays, switches, lead frames and the like.
Here, the strength of rolling was measured by producing a JIS 13B test piece using a press so that the tensile direction was parallel to the rolling direction and performing a tensile test on this test piece in accordance with JIS-Z2241. Direction 0.2% proof stress (YS). From the viewpoint of the above-mentioned application, the 0.2% proof stress is preferably 900 MPa or more, and particularly 950 MPa or more.
Further, the electrical conductivity is evaluated as the electrical conductivity (EC:%IACS) measured by the four-terminal method according to JIS H 0505. From the viewpoint of the above-mentioned use, this conductivity is preferably 30% IACS or more, and particularly 35% IACS or more.

(3) Bendability Surface Roughness In the present invention, bendability is evaluated as the average roughness Ra of the bent portion surface when a W bending test is performed.
That is, when the bending radius (R)/plate thickness (t)=1.0 and the W-bending test is performed in Badway (the bending axis is the same direction as the rolling direction), the smaller the average roughness Ra of the bent portion surface is, the smaller the bending work is. The stress at the time is dispersed, and improvement of bending workability is expected. From this viewpoint, the average roughness Ra of the bent portion surface is preferably 1.0 μm or less.
(4) Number Concentration of Precipitates In the present invention, it is an object to improve the strength, conductivity and bendability by controlling the precipitates. Therefore, it is preferable to evaluate the number of the precipitates. That is, the number concentration of precipitates is counted by counting the number of second-phase particles having a particle size of 5 to 30 nm, divided by the observation area, and the number concentration (×10 ⁹ particles/mm ² ) is calculated. The visual field (each visual field 1 μm×1 μm) is calculated and evaluated as an average value.
Specifically, a cross section parallel to the rolling direction is cut by a focused ion beam (FIB) to expose the cross section, and then a scanning transmission electron microscope (JEOL Model: JEM-2100F) is used. Determine the number concentration of the precipitate to be measured. The number concentration of the precipitates is preferably 0.5×10 ⁹ pieces/mm ² or more, and more preferably 1.5×10 ⁹ pieces/mm ² from the viewpoint of ensuring sufficient strength (0.2% proof stress). It is preferably at least mm ² .
Here, the second phase particles, the crystallized product generated in the solidification process of melt casting and the precipitate generated in the subsequent cooling process, the precipitate generated in the cooling process after hot rolling, in the cooling process after the solution treatment. It refers to a precipitate formed and a precipitate formed in an aging treatment process, and usually has a Co—Si system or Ni—Si system composition, but in the case of the present invention, it has a Ni—Co—Si system composition. Is typical. The size of the second phase particles is defined as the diameter of the largest circle that can be surrounded by the precipitate when the cross section parallel to the rolling direction is microscopically observed with an electron microscope.

(5) Applications The Cu-Ni-Co-Si alloy according to the present invention can be processed into various copper products such as plates, strips, tubes, rods and wires. The copper alloy of the present invention is suitable as, but not limited to, a material for electronic parts such as connectors, battery terminals, jacks, relays, switches and lead frames.

(6) Manufacturing method The Cu-Ni-Co-Si alloy for electronic parts according to the embodiment of the present invention is melt cast of ingot (step 1)-homogeneous annealing, hot rolling, quenching (step 2)-cold rolling. , Solution treatment (step 3)-aging treatment (step 4).

<Ingot manufacturing>
Using an air melting furnace, raw materials such as electrolytic copper, Ni, Co and Si are melted to obtain a molten metal having a desired composition. Then, this molten metal is cast into an ingot. The additive elements other than Ni, Co, and Si are 0 to 2.5 mass in total of 1 or 2 or more selected from the group consisting of Fe, Mg, Sn, Zn, B, P, Cr, Zr, Ti, Al and Mn. % To be added.

<Homogenized annealing and hot rolling>
Since solidification segregation and crystallized substances produced during the production of ingots are coarse, it is desirable to make them as small as possible by forming a solid solution in the mother phase by homogenizing annealing to reduce them. This is because these have an adverse effect on bending workability and are effective in preventing bending cracks by forming a solid solution in the matrix phase.
Specifically, after the ingot manufacturing step, hot rolling is performed after heating to 900 to 1050° C. and homogenizing annealing for 3 to 24 hours. The pass from the original thickness to the overall reduction rate of 90% is preferably 700° C. or higher. Then, it is rapidly cooled to room temperature with water.

<Cold rolling and solution treatment>
After that, cold rolling is performed under the condition that the workability (reduction rate) is 50% or more, preferably 70% or more, and then the solution treatment is performed. Specifically, it is heated to 900 to 1050° C. and heated for 30 seconds to 10 minutes. The solution treatment is intended to form a solid solution of additional elements such as Ni, Co and Si. Therefore, it is important to control the heating rate and the cooling rate in addition to the heating temperature and the heating time. During the temperature rise before the solution treatment, the temperature rise rate of 600 to 700° C., which influences the precipitation of Co-containing second phase particles, is controlled to 50° C./sec or more. On the other hand, the cooling rate in the same temperature range after the solution treatment is also controlled to 50° C./sec or more. Also in other temperature regions, it is preferable that the temperature rising rate and the cooling rate be as high as possible. Further, by adjusting the tension applied to the material at this time to 1 MPa or more and 10 MPa or less, the precipitation of the second phase particles can be controlled more conveniently, and the coefficient of variation of the Ni/Co concentration ratio in the precipitate can be controlled. Of 20% or less, a sufficient number concentration of precipitates having a particle size of 5 to 30 nm can be secured, and sufficient strength can be imparted.

As described above, the precipitation of the Co—Si compound is suppressed by increasing the temperature rising and cooling rates at 600 to 700° C. during the solution treatment, and as a result, the precipitate of the Ni—Co—Si compound is generated. It is believed that Further, the strength of the material during the solution heat treatment was increased by lowering the tension of the material from the conventional level of about 20 MPa. Although this mechanism is unknown, the strain introduced during cold rolling in the previous step was uniformly released by controlling the temperature rising rate, and the strength was increased by the subsequent aging treatment. It is thought that it is.

<Aging treatment>
An aging treatment is performed subsequent to the solution treatment. It is preferable to heat at a material temperature of 400 to 550° C. for 5 to 25 hours, and it is more preferable to heat at a material temperature of 420 to 500° C. for 10 to 20 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 generation of an oxide film.

<Final cold rolling>
After the aging treatment, the final cold rolling is performed. The final cold working can increase the strength, but in order to obtain a good balance of high strength and bendability as intended in the present invention, the reduction ratio is 15 to 45%, preferably 20 to 40. It is desirable to set it as %.

<Strain relief annealing>
Following the final cold rolling, strain relief annealing is performed. It is preferable to heat at a material temperature of 350 to 650° C. for 1 to 3600 seconds, a material temperature of 350 to 450° C. for 1500 to 3600 seconds, a material temperature of 450 to 550° C. for 500 to 1500 seconds, and a material temperature of 550 to 650° C. for 1 to 3. It is more preferable to heat for 500 seconds.

It will be understood by those skilled in the art 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.

Hereinafter, examples of the present invention (examples of the invention) will be shown together with comparative examples, but these are provided for better understanding of the present invention and its advantages, and are not intended to limit the invention. ..

A copper alloy containing each additive element shown in Table 1 and the balance of copper and impurities was melted at 1300° C. in a high frequency melting furnace and cast into an ingot having a thickness of 30 mm. Next, this ingot was heated at 1000° C. for 3 hours, then hot-rolled to a plate thickness of 10 mm, and immediately cooled after completion of hot-rolling. Then, after removing the scale on the surface, chamfering was performed to a thickness of 9 mm, and then cold rolling was performed to obtain a plate having a thickness of 0.120 to 0.175 mm. Next, solution treatment was performed at 950° C. for 120 seconds. Table 1 shows the heating rate, cooling rate, and tension in the temperature range of 600 to 700° C. at this time. After that, aging treatment and cold rolling were added under the conditions of Table 1 to obtain a plate thickness of 0.1 mm. Finally, strain relief annealing was performed at a material temperature of 400° C. for 2000 seconds.

The following evaluation was performed about the produced product sample. The results of evaluation are shown in Table 2.
(1) 0.2% proof stress A JIS 13B test piece was produced using a pressing machine so that the tensile direction was parallel to the rolling direction. The tensile test of this test piece was performed according to JIS-Z2241, and the 0.2% proof stress (YS) in the rolling parallel direction was measured.

(2) Conductivity Based on JIS H 0505, the conductivity (EC:%IACS) was measured by the 4-terminal method.

(3) Surface Roughness of Bent Section According to JIS-H3130 (2012), a W bending test is performed with Badway (the bending axis is the same direction as the rolling direction) and r/t=1.0 (t=0.1 mm), The outer peripheral surface of the bent portion of this test piece was observed. As for the observation method, the outer peripheral surface of the bent portion was photographed using a confocal microscope HD100 manufactured by Lasertec Co., and the average roughness Ra (based on JIS-B0601:2013) was measured using the attached software for comparison. When the surface of the sample before bending was observed with a confocal microscope, no unevenness was confirmed, and 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.

(4) Number concentration of precipitates having a grain size of 5 to 30 nm After a cross section parallel to the rolling direction is cut by a focused ion beam (FIB) to expose the cross section, a scanning transmission electron microscope (JEOL Ltd.) , Model: JEM-2100F) was used to measure the number concentration of precipitates.
Specifically, the acceleration voltage is 200 kV, the observation magnification is 1,000,000 times, the number of the second phase particles having a particle size of 5 to 30 nm is counted, and divided by the observation area to obtain the number concentration (×10 ⁹ particles/mm ² ). Was calculated. Similarly, 20 fields of view were measured, and the average value was used as the number density.

(5) Coefficient of Variation of Ni/Co Concentration Ratio in Precipitate Ni/Co of precipitate using an energy dispersive X-ray analyzer (EDX, manufactured by JEOL Ltd., model: JED-2300) as a detector of STEM. The ratio was measured. The acceleration voltage and the observation magnification were the same as the above conditions, and the electron beam spot diameter was 0.2 nm. The Ni/Co ratio was measured for 100 or more second phase particles. After that, the average value and the standard deviation were calculated to obtain the coefficient of variation (standard deviation/average value×100).

In each of Inventive Examples 1 to 24, the 0.2% proof stress is 900 MPa or more, the electrical conductivity is 30% IACS or more, the surface roughness of the bent portion is 1.0 μm or less, which is good, and The coefficient of variation of the Ni/Co concentration ratio was 20% or less, which was well balanced. It can be said that these copper alloy materials have an excellent balance of high strength, high conductivity, and high bending workability.

Comparative Examples 1 to 18 are specific examples in which the precipitation of the second phase particles could not be sufficiently controlled.
Comparative Example 1 is a specific example in which the temperature rising rate during solution treatment is lower than 50° C./s, and Comparative Example 2 is a specific example in which the cooling rate during solution treatment is lower than 50° C./s. In each of Comparative Examples 1 and 2, it was found that the coefficient of variation of the Ni/Co concentration ratio in the precipitate was 20% or more, and it was difficult to exhibit sufficient bendability.

Comparative Examples 3 and 4 are a specific example (Comparative Example 3) and a specific example (Comparative Example 4) in which the tension applied to the alloy material during the solution treatment is too low and too high, respectively. As a result, a sufficient amount cannot be secured in the number concentration of the precipitates having a grain size of 5 to 30 nm, which is considered to contribute to the strength, and the variation coefficient of the Ni/Co concentration ratio in the precipitate is 20% or more, which is sufficient. It turns out that it is difficult to exert strength.

Comparative Examples 5 and 6 are specific examples in which the heating condition in the aging treatment after the solution treatment deviates from 400 to 550°C. As a result, a sufficient amount cannot be secured in the number concentration of the precipitates having a particle size of 5 to 30 nm that is considered to contribute to the strength, it is difficult to exert sufficient strength, and it is sufficient if the temperature of the aging treatment is too low. It has been found that it is also difficult to exert the conductivity.

Comparative Example 7 is a specific example in which the Ni content in the components of the copper alloy is smaller than 3.0% by mass. It has been found that when the Ni content is small, it is difficult to exert sufficient strength.
Comparative Example 8 is a specific example in which the Ni content in the components of the copper alloy exceeds 4.5 mass %. If the Ni content was high, cracks occurred during hot rolling, and a product could not be obtained.

Comparative Example 9 is a specific example in which Co is not contained in the copper alloy, and Comparative Example 10 is a specific example in which the Co content in the components of the copper alloy exceeds 1.0 mass %. It has been found that it is difficult to exert sufficient bending workability if the Co content is not within the proper range.

Comparative Examples 11 and 12 are a specific example in which the (Ni+Co)/Si mass ratio in the copper alloy is too large (Comparative Example 11) and an excessively small specific example (Comparative Example 12). If the (Ni+Co)/Si mass ratio is not within the proper range, the number concentration of precipitates having a particle size of 5 to 30 nm will not be sufficient, resulting in poor strength and conductivity.

Comparative Examples 13 and 14 are a specific example in which the Ni/Co concentration ratio before the precipitation of the second phase particles in the copper alloy is too small (Comparative Example 13) and an excessively large specific example (Comparative Example 14). In Comparative Examples 13 and 14, it was found that the coefficient of variation of the Ni/Co concentration ratio in the precipitate was 20% or more, and it was difficult to exhibit sufficient bendability.

Comparative Example 15 is a specific example in which the total amount of the third additional elements other than Ni, Co, and Si exceeds 2.5. When the amount of the third additive element is too large, the variation coefficient of the Ni/Co concentration ratio in the precipitate is 20% or more, resulting in inferior bending workability and conductivity.

Comparative Examples 16 to 18 are specific examples in which the tension applied to the alloy material during the solution treatment is large.
Comparative Example 18 is a specific example representing the aspect of Patent Document 3. It was found that the coefficient of variation of the Ni/Co concentration ratio in the precipitate was 20% or more and the number concentration of the precipitates having a particle size of 5 to 30 nm was small, so that it was difficult to exert sufficient strength.
Comparative Example 17 is a specific example that represents the aspect of Patent Document 2 in which the cooling rate during solution treatment is further set to less than 50° C./s. It was found that the coefficient of variation of the Ni/Co concentration ratio in the precipitate was 20% or more, and it was difficult to exhibit sufficient bendability.
In Comparative Example 16, the cooling rate during the solution heat treatment was further reduced to less than 50° C./s, and the aging treatment after the solution heat treatment was performed under a temperature condition lower than a predetermined range. This is a typical example. Also in this case, it was found that the coefficient of variation of the Ni/Co concentration ratio in the precipitate was 20% or more, and it was difficult to exhibit sufficient bendability.

Claims (6)

It contains Ni of 3.0 to 4.5 mass% and Co of 0.1 to 1.0 mass %, and the ratio of Ni to Co (mass %) (Ni/Co) is 3.5 to 30. The second phase particles having a particle size of 5 to 30 nm, which is adjusted so as to contain Si so that the (Ni+Co)/Si mass ratio is 3 to 5, and the balance is Cu and inevitable impurities. Is 0.5×10 ⁹ particles /mm ² or more, and the coefficient of variation of the concentration ratio of Ni to Co (Ni/Co) measured for at least 100 second-phase particles is 20% or less. A Cu-Ni-Co-Si alloy for electronic components. The alloy according to claim 1, further containing at least one selected from the group consisting of Fe, Mg, Sn, Zn, B, P, Cr, Zr, Ti, Al and Mn at a maximum of 2.5 mass% in total. The alloy according to claim 1 or 2 , which has a 0.2% proof stress in a direction parallel to the rolling direction of 900 MPa or more and an electric conductivity of 30% IACS or more. When the bending radius (R)/plate thickness (t)=1.0 and the W-bending test is performed in Badway (the bending axis is in the same direction as the rolling direction), the average roughness Ra of the bent portion surface is 1.0 μm or less. An alloy as claimed in any one of claims 1-3. -Step 1 of melting and casting an ingot of a copper alloy having the composition according to claim 1 or 2;
Step 2 of performing hot rolling after heating at −900° C. or more and 1050° C. or less and quenching to room temperature, and −900° C. or more and 1050° C. or less for 30 seconds while applying tension of 1 MPa or more and 10 MPa or less after cold rolling. A step 3 of performing a solution heat treatment for heating for 10 minutes, and setting a heating rate and a cooling rate in a temperature range between 600° C. and 700° C. to 50° C./second or more before and after the solution heat treatment;
-Aging treatment step 4 in which the material temperature is heated to 400 to 550°C;
Look including to carry out the order,
Thereby, in the copper alloy, the average number of the second phase particles having a particle size of 5 to 30 nm was 0.5×10 ⁹ particles /mm ² or more, and at least 100 second phase particles were measured. A method for producing a copper alloy, wherein the coefficient of variation of the concentration ratio of Ni to Co (Ni/Co) is 20% or less . Electronic component having an alloy according to any one of claims 1-4.