Cu-Ni-Co-Si-BASED COPPER ALLOY, TERMINAL, AND ELECTRONIC COMPONENT

Abstract

Provided are a Cu-Ni-Co-Si-based copper alloy, a terminal, and an electronic component, which exhibit greater reductions in permanent fatigue. The Cu-Ni-Co-Si-based copper alloy according to the present disclosure contains 1.0-4.0 mass% Ni, 0.1-1.0 mass% Si, and 0.0-1.5 mass% Co, with the remainder being Cu and unavoidable impurities, and has an H / t of not more than 1.04, where H / t is the value, determined as follows, yielded by dividing the amount of permanent strain H (mm) by the plate thickness t (mm). A 5 mm-wide test specimen supported in a cantilevered manner at room temperature is subjected, at a position on the free end at a gauge length of 1 mm from the fixed part, to loading and unloading using a knife edge at a stroke displacement of 0.34 mm and a speed of 1 mm / minute. The permanent strain H (mm) is the amount of permanent deformation at the position of the gauge length when this loading and unloading has been carried out a total of ten times.

Description

Cu-Ni-Co-Si based copper alloy, terminal, and electronic component

[0001] The present disclosure relates to a Cu—Ni—Co—Si-based copper alloy, a terminal, and an electronic component.

[0002] Solid-solution-strengthened alloys such as brass and phosphor bronze have traditionally been used as materials for terminals and connectors. As electronic devices become more powerful, copper alloys used therein are required to have improved strength and electrical conductivity. Therefore, precipitation-strengthened copper alloys (e.g., Corson alloys), which have superior strength and electrical conductivity compared to conventional solid-solution-strengthened copper alloys, have been used. Precipitation-strengthened copper alloys are formed by aging a solution-treated supersaturated solid solution, which uniformly disperses fine precipitates, increasing the strength of the alloy and reducing the amount of solid-solution elements in the copper, thereby improving electrical conductivity. Therefore, precipitation-strengthened copper alloys can have excellent mechanical properties and electrical conductivity.

[0003] A Cu-Ni-Co-Si based copper alloy, a type of Corson alloy, has been developed as a precipitation-strengthened copper alloy (Patent Document 1). When a Cu-Ni-Co-Si based copper alloy is used as a spring material, there is a problem of permanent deformation known as "sag." Therefore, the technology in Patent Document 1 reduces sag by precipitating fine second-phase particles in the matrix.

[0004] International Publication No. 2010 / 064547

[0005] However, in recent years, there has been a demand for further reduction in sag that can occur in copper alloys. An object of the present disclosure is to provide a Cu-Ni-Co-Si-based copper alloy with further reduced sag, a terminal including the copper alloy, and an electronic component including the terminal.

[0006] The Cu-Ni-Co-Si-based copper alloy of the present disclosure contains 1.0 to 4.0 mass % Ni, 0.1 to 1.0 mass % Si, and 0.0 to 1.5 mass % Co, with the remainder being Cu and unavoidable impurities, and has a value of H / t of 1.04 or less, obtained by supporting a 5 mm wide test piece in a cantilever manner at room temperature, loading and unloading being performed with a knife edge at a position 1 mm in gauge length from a fixed part of a free end of the test piece at a rate of 1 mm / min with a stroke of 0.34 mm, and repeating the loading and unloading 10 times in total. The value is obtained by dividing the settling amount H (mm), which is the amount of permanent deformation at the position of the gauge length, by the plate thickness t (mm).

[0007] A terminal of the present disclosure includes the Cu—Ni—Co—Si-based copper alloy. An electronic component of the present disclosure includes the terminal.

[0008] According to the present disclosure, it is possible to provide a Cu-Ni-Co-Si based copper alloy with even further reduced settling, a terminal including the copper alloy, and an electronic component including the terminal.

[0009] 1 is a diagram illustrating a method for measuring the amount of settling, and the left-right direction of Fig. 1 corresponds to the long side direction of the test piece, and the front-rear direction of Fig. 1 corresponds to the width direction of the test piece.

[0010] Hereinafter, Cu—Ni—Co—Si-based copper alloys according to embodiments of the present disclosure will be described. In the present disclosure, “A to B” means “A or more and B or less.”

[0011] The present disclosure can be embodied in the following aspects. [1] A Cu-Ni-Co-Si-based copper alloy containing 1.0 to 4.0 mass% Ni, 0.1 to 1.0 mass% Si, and 0.0 to 1.5 mass% Co, with the balance being Cu and unavoidable impurities, wherein a 5 mm-wide test piece is supported in a cantilevered manner at room temperature, and loading and unloading is performed using a knife edge at a position 1 mm in gauge length from a fixed part of a free end of the test piece at room temperature at a rate of 1 mm / min with a stroke of 0.34 mm, and the loading and unloading is performed a total of 10 times. The value of H / t is obtained by dividing the amount of permanent deformation at the position of the gauge length, H (mm), by the plate thickness t (mm), and the value is 1.04 or less. [2] A Cu-Ni-Co-Si-based copper alloy according to [1], in which the amount of permanent deformation at the position of the gauge length, H, is 0.052 mm or less. [3] A Cu-Ni-Co-Si-based copper alloy according to [1] or [2], wherein the H / t is 0.45 or more. [4] A Cu-Ni-Co-Si-based copper alloy according to any one of [1] to [3], wherein the H / t is 0.92 or less. [5] A Cu-Ni-Co-Si-based copper alloy according to any one of [1] to [4], wherein the plate thickness t is 0.04 to 0.40 mm. [6] A Cu-Ni-Co-Si-based copper alloy according to any one of [1] to [5], wherein the mass ratio of Ni to Si is 3.5 to 5.0. [7] A Cu-Ni-Co-Si-based copper alloy according to any one of [1] to [6], wherein the 0.2% proof stress in the direction parallel to the rolling measured in accordance with JIS-Z2241 is 900 MPa or more. [8] The Cu-Ni-Co-Si-based copper alloy according to any one of [1] to [7], which has an electrical conductivity of 35% IACS or more at 25°C measured in accordance with JIS-H0505. [9] The Cu-Ni-Co-Si-based copper alloy according to any one of [1] to [8], which further contains at least one element selected from the group consisting of Mg, Mn, Sn, Zn, and Cr in a total amount of 0.0050 to 1.0 mass%.

[10] The Cu-Ni-Co-Si-based copper alloy according to any one of [1] to [9], which further contains at least one element selected from the group consisting of P, B, Ti, Zr, Al, Fe, and Ag in a total amount of 0.0050 to 1.0 mass%.

[0012]

[11] A terminal comprising the Cu-Ni-Co-Si-based copper alloy according to any one of [1] to

[10] .

[12] An electronic component comprising the terminal according to

[11] .

[0013] A Cu-Ni-Co-Si-based copper alloy (hereinafter, "Cu-Ni-Co-Si-based copper alloy" may be referred to as "copper alloy") according to the present disclosure contains 1.0 to 4.0 mass% Ni, 0.1 to 1.0 mass% Si, and 0.0 to 1.5 mass% Co, with the remainder being Cu and inevitable impurities, and has a value of H / t of 1.04 or less, obtained by supporting a 5 mm wide test piece in a cantilever manner at room temperature, loading and unloading being performed with a knife edge at a position 1 mm in gauge length from a fixed part of the free end of the test piece at room temperature, at a rate of 1 mm / min with a stroke of 0.34 mm, and dividing the amount of permanent deformation H (mm) at the position of the gauge length by the plate thickness t (mm) when the loading and unloading are performed a total of 10 times.

[0014] According to the above configuration, a Cu—Ni—Co—Si-based copper alloy with further reduced settling can be obtained. In recent years, materials with high strength and high conductivity have been required, for example, along with miniaturization and increased current carrying capacity of terminals. The Cu—Ni—Co—Si-based copper alloy of the present disclosure also has high strength and conductivity. The Cu—Ni—Co—Si-based copper alloy is a type of Corson alloy. The strength of a Corson alloy is expected to improve as the total amount of Ni and Co, which contribute to precipitation strengthening, increases. In precipitation-strengthened Cu—Ni—Co—Si-based copper alloys, finish rolling and stress relief annealing are performed as necessary after aging treatment. Furthermore, polishing is performed to remove the oxide film on the surface that forms during stress relief annealing. Pickling may be performed before polishing.

[0015] However, it was found that polishing scrapes the surface of the material, causing residual stress on the surface and increasing the amount of settling. Therefore, the inventors discovered that settling can be further reduced by not polishing after stress relief annealing. The smaller the settling, the more compact the terminals and the like can be.

[0016] (Composition) [Ni and Si] The copper alloy of the present disclosure contains 1.0 to 4.0 mass% Ni and 0.1 to 1.0 mass% Si, based on 100 mass% of the copper alloy. Ni and Si form an intermetallic compound by appropriate heat treatment. This allows the strength of the copper alloy to be improved without degrading its electrical conductivity. In the copper alloy of the present disclosure, the mass ratio of Ni to Si (hereinafter referred to as the "Ni / Si ratio") may be 3.5 to 5.0. If the Ni or Si content is less than the above range, the effect of improving strength cannot be obtained, and if it exceeds the above range, electrical conductivity and hot workability decrease. If the Ni / Si ratio is less than 3.5 or more than 5.0, electrical conductivity may decrease. [Co] The copper alloy of the present disclosure contains 0.0 to 1.5 mass% Co. If the Co content exceeds 1.5 mass %, the Co that is unable to form intermetallic compounds with Ni and Si acts to reduce electrical conductivity, thereby deteriorating hot workability.

[0017] [Other Additional Elements] The copper alloy of the present disclosure may further contain at least one element selected from the group consisting of Mg, Mn, Sn, Zn, and Cr (hereinafter referred to as the "first additional element") in a total amount of 0.0050 to 1.0 mass%. The copper alloy of the present disclosure may preferably contain 0.050 mass% or more and / or 0.50 mass% or less of the first additional element. Mg can improve the strength and stress relaxation resistance of the copper alloy. Mn can improve the strength and hot workability of the copper alloy. Sn can improve the strength of the copper alloy. Zn can improve the heat resistance of solder joints. Like Ni, Cr forms a compound with Si and undergoes precipitation hardening, thereby improving strength without degrading electrical conductivity. If the total amount of the first additional element is less than the above range, the above-mentioned effects are difficult to achieve. Furthermore, if the total amount of the first additional element exceeds the above range, electrical conductivity may be reduced. The copper alloy of the present disclosure may preferably contain 0.010% by mass or more and / or 0.2% by mass or less of the first additional element.

[0018] The copper alloy of the present disclosure may further contain at least one element selected from the group consisting of P, B, Ti, Zr, Al, Fe, and Ag (hereinafter referred to as the "second additional element") in a total amount of 0.0050 to 1.0 mass %, which can improve product properties such as electrical conductivity, strength, stress relaxation properties, and plating properties.

[0019] If the total amount of the second additive element is less than the above range, the above-mentioned effect cannot be obtained, and if the total amount exceeds the above range, the electrical conductivity may be reduced. The copper alloy of the present disclosure may preferably contain 0.010 mass % or more and / or 0.2 mass % or less of the second additive element.

[0020] [Balance] The balance of the copper alloy of the present disclosure (i.e., other than the above-mentioned elements) consists of Cu and inevitable impurities. Examples of inevitable impurities include S and O. The content of each element contained as an inevitable impurity is not particularly limited, but is, for example, 100 ppm by mass or less. The lower limit of each element of the inevitable impurities is not particularly limited, but is typically 0 ppm by mass or more.

[0021] (Composition Measurement) The composition of the copper alloy can be measured by X-ray fluorescence analysis. A Rigaku Simultix 14 or equivalent can be used as the X-ray fluorescence analyzer. The analysis surface can be machined or mechanically polished so that the maximum surface roughness Rz (JIS-B0601 (2013)) is 6.3 μm or less. When collecting an analysis sample from the molten metal during melting and casting, the sample can be cast into a shape of approximately 30 to 40 mm diameter and approximately 50 to 80 mm thick, then cut to a thickness of approximately 10 to 20 mm, and the cut surface can be used as the analysis surface. The composition of the copper alloy can also be measured by wet analysis. Ni can be measured using the copper separation dimethylglyoxime gravimetric method (JIS-H1056 (2003)), and Si can be measured using the silicon dioxide gravimetric method (JIS-H1061 (2006)). Other additive elements and impurity elements can be measured using ICP atomic emission spectroscopy. In the case of ICP optical emission spectroscopy, the measurement may be performed using an ICP optical emission spectroscopy analyzer (ICP-OES) SPS3100 manufactured by Hitachi High-Tech Science Corporation or an equivalent device. In the case of ICP optical emission spectroscopy, a copper alloy sample may be dissolved in a mixed acid containing hydrochloric acid, nitric acid, and water in a volume ratio of 2:1:2, and then diluted and used.

[0022] (Shape) The shape of the copper alloy of the present disclosure is not particularly limited, and can be, for example, a copper alloy sheet obtained by a manufacturing method including a rolling step as described below. The copper alloy sheet is not particularly limited as long as it is an object having a three-dimensional shape with a certain thickness, and also includes, for example, strip, plate, and foil as defined in JIS H 0500. The copper alloy of the present disclosure may be in the form of a plate. That is, the copper alloy of the present disclosure may be a copper alloy sheet. A "strip" (or "ribbon") may mean "a slit coil shape having a substantially uniform thickness and a rectangular cross section." A "sheet" (or "plate") may mean "a sheared or sawed shape having a substantially uniform thickness and a rectangular cross section," and may be in a flat shape. A plate having a thin thickness (e.g., less than 0.1 mm) can also be called a "foil." The thickness of the copper alloy of the present disclosure may be 0.04 to 0.40 mm. In the present disclosure, the thickness of the copper alloy plate may be referred to as the "plate thickness."

[0023] (H / t) In the copper alloy of the present disclosure, H / t, which is the value obtained by dividing the amount of sag H (mm) measured by the method described below by the sheet thickness t (mm) of the copper alloy, is 1.04 or less. FIG. 1 is a diagram illustrating a method for measuring the amount of sag. First, a rectangular test piece 2 having a short side length of 5 mm and a long side length of 100 mm is prepared using the copper alloy of the present disclosure. The long side of the test piece 2 is parallel to the rolling direction of the copper alloy. Hereinafter, the "short side length" may also be referred to as "width." Next, the test piece 2 is clamped and supported in a cantilever manner by a vise 10 or the like, and the tip of the knife edge 20 is placed at a position (also referred to as position P) at the center of the short side direction, where the gauge length L from the fixed part of the free end (the part of the test piece 2 not clamped) is 1 mm. The knife edge 20 is displaced in the thickness direction of the copper alloy at a speed of 1 mm / min so that the stroke S is 0.34 mm, and an external force is applied, and then the external force is released. The permanent deformation of the test piece 2 caused by repeating the loading and unloading of an external force 10 times as one set is the amount of permanent deformation H (mm) measured from the initial state at position P. The amount of permanent deformation is measured, for example, at room temperature (25°C).

[0024] A precision load testing machine can be used to measure the amount of sag. When H / t is 1.04 or less, it can be said that the amount of sag is further reduced. H / t is preferably 0.92 or less. Although the lower limit of H / t is not limited to the following, H / t is preferably 0.45 or more. The amount of sag H is preferably 0.052 mm or less. The amount of sag H of the copper alloy of the present disclosure is smaller in gauge length L and stroke S than those in Patent Document 1. Furthermore, a higher load is applied in measuring the amount of sag H than in Patent Document 1, and the measurement is performed under conditions that make the amount of sag more likely to increase.

[0025] (0.2% Proof Stress and Electrical Conductivity) The copper alloy of the present disclosure may have a 0.2% proof stress in the direction parallel to the rolling direction of 900 MPa or more, measured in accordance with JIS-Z2241. The copper alloy of the present disclosure may have an electrical conductivity at 25°C of 35% IACS or more, measured in accordance with JIS-H0505. In order to accommodate further miniaturization and thinning of electrical and electronic components using Cu-Ni-Co-Si-based copper alloys, a strength level of 0.2% proof stress in the direction parallel to the rolling direction (LD) of 900 MPa or more is desired. Therefore, the copper alloy of the present disclosure is suitable for use in small and thin-walled electrical and electronic components. In the copper alloy of the present disclosure, the 0.2% proof stress in the direction parallel to the rolling direction is more preferably 950 MPa or more, and may be, for example, 980 MPa or more. The 0.2% proof stress in the direction parallel to the rolling direction is even more preferably 1000 MPa or more. The upper limit is not particularly limited, but may typically be 1200 MPa or less. In the copper alloy of the present disclosure, the 0.2% proof stress in the direction parallel to the rolling may be 942 MPa or more and 1007 MPa or less, or 980 MPa or more and 1007 MPa or less.

[0026] Specific conditions for the tensile test to measure 0.2% proof stress and specific conditions for measuring electrical conductivity can be the conditions described in the Examples section below. As a tensile tester used for the tensile test, an Autocom AC-100KN-C manufactured by TSE Co., Ltd. or an equivalent device can be used. In the copper alloy of the present disclosure, the electrical conductivity is more preferably 40% IACS or more, and may be, for example, 40.2% IACS or more. In the copper alloy of the present disclosure, the electrical conductivity may be 40.2% IACS or more and 43.7% IACS or less.

[0027] (Manufacturing Method) The copper alloy of the present disclosure can be produced, for example, by the following manufacturing process. Melting and casting, homogenization annealing, hot rolling, facing, cold rolling, solution treatment, aging treatment, finish rolling, stress relief annealing, and degreasing are performed in this order. Polishing is not performed between stress relief annealing and degreasing. Heat treatment may be performed, if necessary, between hot rolling and solution treatment.

[0028] In the melting and casting process, a copper alloy ingot is produced. Specifically, electrolytic copper is melted in an atmospheric melting furnace, and a predetermined amount of additive elements is added. The molten metal is stirred and then cooled to obtain a copper alloy ingot. Hot rolling may be performed in several passes. The total reduction ratio of the hot rolling can be, for example, 85% or more. The reduction ratio (%) is expressed as follows: [(TB - TA) / TB] x 100, where TB is the thickness of the target to be rolled before rolling and TA is the thickness of the target after rolling. Aging treatment is performed to improve precipitation hardening and electrical conductivity. The aging treatment conditions are preferably 400 to 600°C and 8 to 48 hours. If the temperature or time exceeds the upper limit, softening occurs, and if it falls below the lower limit, strength or electrical conductivity is insufficient. Finish rolling is performed to achieve work hardening. The reduction ratio is preferably 10 to 95%. If the working ratio is 10% or more, the copper alloy can have sufficient strength. If the working ratio is 95% or less, rolling can be performed without saturating the strength, and the rolling time can be prevented from becoming extremely long. Strain relief annealing is performed to improve low-temperature annealing hardening and electrical conductivity. The conditions for strain relief annealing are preferably 250 to 900°C and 1 second to 36 hours. The conditions for strain relief annealing can be, for example, 300°C and 16 hours. If the temperature or time exceeds the upper limit, softening occurs, and if it falls below the lower limit, strength or electrical conductivity will be insufficient. In this way, by not polishing after strain relief annealing, it is possible to prevent the material surface from being scraped by polishing. This suppresses the generation of residual stress on the material surface, further reducing sag.

[0029] (Terminals and Electronic Components) Terminals can be manufactured using the Cu—Ni—Co—Si-based copper alloy of the present disclosure, and more preferably, terminals are manufactured using the copper alloy as a spring material. Electronic components can be manufactured using the terminals. Examples of electronic components include CPU sockets, type C connectors, lead frames, and FPC connectors.

[0030] Using the above-described manufacturing method, solution-treated copper alloys containing the additive elements shown in Table 1 were obtained. Next, aging treatment and finish rolling were performed in this order. After finish rolling, stress relief annealing was performed. Furthermore, after stress relief annealing, degreasing was performed without polishing. The aging treatment was performed at 450 to 520°C for 10 to 20 hours. The degree of reduction in the finish rolling was 20 to 60%. Strain relief annealing was performed at 280°C for 8 hours, at 300°C for 8 hours, or at 600°C for 20 seconds. As a result, copper alloys of the examples having the thicknesses listed in Table 1 were obtained. In Comparative Example 1, pickling and polishing were performed in this order between stress relief annealing and degreasing. Except for this, the copper alloy of Comparative Example 1 was obtained in the same manner as in Example 5. The composition of the obtained copper alloy was confirmed by X-ray fluorescence. A Rigaku Simultix 14 X-ray fluorescence analyzer was used. The analyzed surface was cut or mechanically polished so that the maximum surface roughness Rz (JIS-B0601 (2013)) was 6.3 μm or less. The copper alloys of the examples and comparative examples contained 0.50 mass% or less of Cr, Mg, Zn, Fe, and Mn in total.

[0031] <Evaluation> The following items were evaluated using the obtained copper alloys. [Electrical Conductivity] For samples in the direction parallel to the rolling direction, electrical conductivity (% IACS) was calculated from the volume resistivity determined at 25°C by the four-terminal method using a double bridge device in accordance with JIS-H0505. [0.2% Yield Strength] JIS No. 13B test pieces were prepared using a press so that the tensile direction was parallel to the rolling direction. A tensile test was performed on these test pieces in accordance with JIS-Z2241 to measure the 0.2% yield strength. A tensile test was performed in the rolling direction of the copper foil under the following tensile test conditions. Test piece width: 12.5 mm Room temperature: 15 to 35°C Tensile speed: 5 mm / min Load cell rating: 10 kN Load range: 5% Return speed: 500 mm / min Gauge length L: 50 mm

[0032] [Sag H] Using the obtained copper alloy, the sag H was measured as shown in FIG. 1 , and H / t was calculated. Specifically, a rectangular test piece 2 with a short side length of 5 mm and a long side length of 100 mm was prepared using the obtained copper alloy. The long side of the test piece 2 was parallel to the rolling direction of the copper alloy. Next, the test piece 2 was clamped in a cantilever manner by a vise 10 or the like, and the tip of the knife edge 20 was placed at a position (also referred to as position P) at the center of the short side direction, where the gauge length L from the fixed part of the free end (the part of the test piece 2 not clamped) was 1 mm. The knife edge 20 was displaced in the thickness direction of the copper alloy at a speed of 1 mm / min so that the stroke S was 0.34 mm, and an external force was applied, and then the external force was released. The loading and unloading of the external force was repeated 10 times as one set, and the permanent deformation of the test piece 2, measured at position P, was taken as the sag H (mm). The amount of settling was measured twice at room temperature (25°C), and the maximum value was used. Note that a precision load testing machine was used to measure the amount of settling.

[0033] [Socket settling strength] Socket settling strength is measured by processing a material into a specified socket, measuring the height of the pin after it is pressed in, and judging whether the height is above the manufacturing target value or not, and whether it is below the manufacturing target value or not. In the example, a test socket of 200 pin class was created, and the original terminal height was 0.3 mm. The terminal was pressed in five times to the full height (0.3 mm), and the height after pressing was measured. Since the terminal height after the test must be 0.2 mm or more, a height above that is good, and a height below that is bad.

[0034] The results obtained are shown in Table 1. Although the socket set strength of Examples 3 and 4 was not actually evaluated, it is presumed that the socket set strength would be better because the H / t values ​​were smaller than those of Examples 1 and 2. For Example 5, polishing was not performed as in Examples 1 and 2, and therefore it is presumed that the socket set strength would be better than that of Comparative Example 1, which was polished.

[0035]

[0036] As is clear from Table 1, in the cases of the examples in which polishing was not performed after stress relief annealing, H / t was 1.04 or less, and settling was reduced.

[0037] On the other hand, in the case of Comparative Example 1 in which polishing was performed after stress relief annealing, H / t exceeded 1.04, and settling could not be reduced.

Claims

1. A Cu-Ni-Co-Si system copper alloy containing 1.0 to 4.0 mass% Ni, 0.1 to 1.0 mass% Si, and 0.0 to 1.5 mass% Co, with the remainder being Cu and unavoidable impurities, in which a test piece 5 mm wide is supported in a cantilever manner at room temperature, and loading and unloading is performed at a position 1 mm in gauge length from a fixed part of the free end of the test piece at a speed of 1 mm / min and a stroke of 0.34 mm, with the load and unloading being performed a total of 10 times, and the value of H / t, which is the value obtained by dividing the amount of permanent deformation, H (mm), at the position of the gauge length, by the plate thickness t (mm), is 1.04 or less.

2. A Cu-Ni-Co-Si based copper alloy according to claim 1, wherein the amount of settling H is 0.052 mm or less.

3. The Cu-Ni-Co-Si based copper alloy according to claim 1, wherein the H / t is 0.45 or more.

4. A Cu-Ni-Co-Si based copper alloy according to claim 1 or 3, wherein the H / t is 0.92 or less.

5. A Cu-Ni-Co-Si based copper alloy according to claim 1 or 2, wherein the plate thickness t is 0.04 to 0.40 mm.

6. A Cu-Ni-Co-Si based copper alloy according to claim 1 or 2, wherein the mass ratio of Ni to Si is 3.5 to 5.

0.

7. A Cu-Ni-Co-Si based copper alloy according to claim 1 or 2, which has a 0.2% yield strength in a direction parallel to the rolling direction measured in accordance with JIS-Z2241 of 900 MPa or more.

8. A Cu-Ni-Co-Si based copper alloy according to claim 1 or 2, which has an electrical conductivity of 35% IACS or more at 25° C. as measured in accordance with JIS-H0505.

9. A Cu-Ni-Co-Si based copper alloy according to claim 1 or 2, further containing at least one element selected from the group consisting of Mg, Mn, Sn, Zn and Cr in a total amount of 0.0050 to 1.0 mass%.

10. A Cu-Ni-Co-Si based copper alloy according to claim 1 or 2, further containing at least one element selected from the group consisting of P, B, Ti, Zr, Al, Fe and Ag in a total amount of 0.0050 to 1.0 mass%.

11. A terminal comprising the Cu-Ni-Co-Si based copper alloy according to claim 1 or 2.

12. An electronic component comprising the terminal according to claim 11.

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