TWI911835B - Copper alloys and electronic components - Google Patents

Abstract

The purpose of this invention is to provide a copper alloy with high conductivity and high strength, and electronic components containing the same. The copper alloy of this invention contains 2.3–4.6% by mass Ni, 0.10–0.50% by mass Co, 0.60–1.3% by mass Si, and 0.010–0.10% by mass Cr, with the remainder consisting of Cu and unavoidable impurities.

Description

Copper alloys and electronic components

This invention relates to a copper alloy and electronic components.

Carson alloys are copper-based alloys containing intermetallic compounds such as Ni-Si, Co-Si, and Ni-Co-Si, exhibiting both high strength and high conductivity. Due to these properties, Carson alloys are used as copper alloy components in electronic devices, for example, in semiconductor packages as lead frames to support and fix semiconductor devices and form internal wiring (see, for example, Patent 1). [Prior Art Documents] [Patent Documents]

[Patent Document 1] Japanese Patent Application Publication No. 2018-035437

[The problem the invention aims to solve]

With the increasing functionality of electronic components in recent years, copper alloy parts (or specific portions of copper alloy parts) made of Carson's alloy are becoming increasingly miniaturized. This necessitates that copper alloys possess high conductivity while simultaneously enhancing their properties to accommodate this miniaturization. For example, in semiconductor packages, which are electronic components, the increasing functionality and miniaturization of semiconductor package structures have led to larger package sizes. Consequently, the lead frames constructed from copper alloys within semiconductor packages, and especially the leads within those lead frames, are also continuously becoming miniaturized. Leads are the internal wiring (pins) within a semiconductor package used to connect to external wiring. Due to miniaturization, lead lengths have increased or the spacing between leads has narrowed. However, this miniaturization sometimes makes it difficult for leads to possess sufficient strength. During leadframe or semiconductor package manufacturing processes (e.g., the process of creating the desired leadframe from a copper alloy plate through semi-etching, or the wire bonding process to connect leads to semiconductor components after placing them in the leadframe), lead deformation can occur, making it difficult to maintain their shape with high precision. As a result, semiconductor packages cannot always be manufactured efficiently, and for copper alloys, further increases in strength are required.

The purpose of this invention is to provide a copper alloy with high conductivity and high strength, and electronic components containing the same. [Technical Means for Solving the Problem]

In one embodiment, the copper alloy of the present invention contains 2.3 to 4.6% by mass of Ni, 0.10 to 0.50% by mass of Co, 0.60 to 1.3% by mass of Si, and 0.010 to 0.10% by mass of Cr, with the remainder consisting of Cu and unavoidable impurities.

In one embodiment, the electronic component of the present invention comprises the copper alloy described above. [Effects of the Invention]

This invention provides a copper alloy with high conductivity and high strength, and electronic components containing the same.

The embodiments of the present invention (hereinafter also referred to as "the embodiments") are described in detail below, but the present invention is not limited to the embodiments described below. In the present invention, "A to B" means "A or more and B or less". Here, A and B represent numerical values.

[Copper Alloy] The copper alloy of this embodiment contains 2.3–4.6% by mass Ni, 0.10–0.50% by mass Co, 0.60–1.3% by mass Si, and 0.010–0.10% by mass Cr, with the remainder consisting of Cu and unavoidable impurities. That is, the copper alloy of this embodiment is a Cu-Ni-Co-Si alloy. Ni, Co, and Si can be precipitated into Ni-Co-Si intermetallic compound particles through appropriate heat treatment, achieving high conductivity and high strength.

In this embodiment of the copper alloy, the Ni concentration is 2.3–4.6% by mass, the Co concentration is 0.10–0.50% by mass, and the Cr concentration is 0.010–0.10% by mass. This maintains the high electrical conductivity of the copper alloy while simultaneously increasing its strength. When the Ni concentration is less than 2.3% by mass, the desired strength cannot be obtained. When the Co concentration is less than 0.10% by mass, the desired strength or electrical conductivity cannot be obtained. When the Cr concentration is less than 0.010% by mass, the desired strength cannot be obtained. When the Ni concentration exceeds 4.6% by mass, sufficient strength can be obtained, but conductivity decreases. Similarly, when the Co concentration exceeds 0.50% by mass, while sufficient conductivity is obtained, high strength is difficult to achieve. When the Cr concentration exceeds 0.10% by mass, Cr forms compounds with other components, making it difficult to form the target Ni-Co-Si precipitates. As a result, the desired strength cannot be obtained. The preferred Ni concentration is 2.8–4.4% by mass, more preferably 3.0–4.0% by mass, and even more preferably 3.3–3.7% by mass. Furthermore, the Co concentration is preferably less than 0.50% by mass, more preferably 0.10–0.40% by mass, and even more preferably 0.20–0.30% by mass. The Cr concentration is preferably 0.020–0.070% by mass, and even more preferably 0.040–0.060% by mass.

In the copper alloy of this embodiment, the Si concentration is 0.6–1.3% by mass. This maintains the high conductivity of the copper alloy while simultaneously improving its strength. If the Si concentration is less than 0.60% by mass, the desired strength cannot be obtained. Furthermore, if the Si concentration exceeds 1.3% by mass, although sufficient strength is achieved, conductivity will decrease. The Si concentration is preferably 0.7–1.2% by mass, more preferably 0.8–1.0% by mass.

As mentioned above, the Ni-Co-Si precipitates formed by Ni, Co, and Si are considered to be intermetallic compounds mainly composed of (Ni+Co)Si. However, Ni, Co, and Si in copper alloys may not all become precipitates due to the aging treatment during the manufacturing process of the copper alloy sheet; they may exist to some extent in a solid-dissolved state within the Cu matrix. The solid-dissolved Ni, Co, and Si can slightly increase the strength of the copper alloy sheet, but this effect is smaller compared to the precipitated state, and may become the main cause of decreased conductivity. Therefore, the ratio of Ni, Co, and Si content is preferably close to the composition ratio of (Ni+Co)Si. Therefore, the mass ratio (RA ₎ of Ni and Co to Si is preferably 3.5–5.0, more preferably 3.5–4.5.

As mentioned above, Ni-Co-Si precipitates contribute to improving the strength and conductivity of copper alloys. Ni primarily contributes to increasing the strength of copper alloys, while Co primarily contributes to increasing their conductivity. Therefore, from the perspective of maintaining high conductivity while simultaneously improving strength, the mass ratio of Co to Ni, _RB, can be set to 0.010 to 0.155. A Co-to-Ni mass ratio _RB of 0.010 or higher maintains high conductivity in copper alloys. A Co-to-Ni mass ratio _RB of 0.155 or lower effectively improves the strength of copper alloys. A _RB ratio of 0.025 to 0.155 is preferred, and more preferably 0.056 to 0.086.

In the composition of the copper alloy of this embodiment, in addition to the elements mentioned above, one or more elements selected from the group consisting of Mg, Fe, P, Cr, Ag, Zn, Sn, Pb, Zr, Al, As, Se, Te, Sb, Bi, Au, Ti, Nb, V, Ta, W, Mo, and Mn (hereinafter also referred to as "added elements") may be included in a total of 0.010 to 1.0% by mass. This improves the strength, heat resistance, and stress mitigation properties of the copper alloy. When the total amount of added elements is 0.010% by mass or more, the desired effects are more easily obtained. Furthermore, when the amount is 1.0% by mass or less, the desired properties can be obtained while preventing a decrease in conductivity. The total amount of added elements is preferably 0.020–0.080% by mass, more preferably 0.050–0.080% by mass.

In this embodiment, the remainder other than the components mentioned above consists of Cu and unavoidable impurities. Here, unavoidable impurities refer to impurity elements that cannot be avoided from being incorporated into the material during the manufacturing process. The concentration of each element as an unavoidable impurity can be, for example, set to less than 0.015% by mass, preferably 0% (undetectable). The composition of the copper alloy can also be determined by wet analysis. Ni can be determined using the copper separation dimethylglyoxime gravimetric method (JIS-H1056 (2003)), and Si can be determined using the silicon dioxide gravimetric method (JIS-H1061 (2006)). Other added elements and impurities can be analyzed using ICP-OES. The analysis of other added elements is performed using an internal standard method, with Y (yttrium) used as the internal standard. Elements other than Y can also be selected as the internal standard. ICP-OES analysis is performed using a Hitachi Advanced Technology & Science Corporation ICP-OES apparatus (ICP-OES) SPS3100 or an equivalent apparatus. In the case of ICP-OES analysis, the copper alloy sample is dissolved in a mixed acid containing hydrochloric acid and nitric acid (in a volume ratio of 2:1:2 containing hydrochloric acid, nitric acid, and water), diluted, and then used. Furthermore, the composition of the copper alloy can also be determined using fluorescent X-ray analysis. As a fluorescent X-ray analysis apparatus, Rigaku's Simultix14 or an equivalent apparatus can be used. The analysis surface can be prepared by cutting or mechanically grinding to achieve a maximum surface roughness Rz (JIS-B0601 (2013)) of 6.3 μm or less. When collecting samples for fluorescent X-ray analysis from the molten metal during melting casting, after casting to a shape of approximately 30–40 mm Φ and 50–80 mm thickness, cut the sample to a thickness of approximately 10–20 mm, and then use the cut surface as the analysis surface. Fluorescent X-ray analysis is performed based on JIS K 0119:2008, using wavelength dispersion.

The copper alloy used in this embodiment is not particularly limited, and for example, a copper alloy sheet can be manufactured by a manufacturing method including a rolling step, as described below. As a copper alloy sheet, there is no particular limitation on whether it is a three-dimensional object composed of the above-described components and having a specified thickness. The term "plate" in the context of the copper alloy sheet also includes sheets, strips, and foils. Furthermore, the copper alloy sheet includes, for example, not only copper alloy sheets before processing for use in electronic components, but also copper alloy sheets in the process of processing or after processing. The thickness of the copper alloy sheet is, for example, 0.030 to 1.2 mm. This thickness is preferably 0.050 to 0.60 mm, and more preferably 0.080 to 0.30 mm.

The copper alloy of this embodiment, due to its composition as described above, possesses high conductivity and strength. Specifically, the tensile strength of the copper alloy of this embodiment, in a copper alloy sheet manufactured through a rolling process, in the direction parallel to the rolling direction can reach 870 MPa or higher. Because of this high tensile strength, deformation that may occur during the manufacturing process of electronic components, specifically including the step of processing copper alloy sheets to manufacture copper alloy parts (e.g., lead frames), is suppressed. The tensile strength in the direction parallel to the rolling direction is preferably 930 MPa or higher, more preferably 940 MPa or higher, and even more preferably 950 MPa or higher. There is no particular upper limit to the tensile strength in the direction parallel to the rolling direction; for example, it may be 1200 MPa or lower, 1100 MPa or lower, or 1000 MPa or lower.

The tensile strength in the direction parallel to the rolling direction can be measured using a tensile testing machine according to JIS-Z2241 (2011). Specifically, JIS 13B test pieces are prepared from each sample using a pressing machine with the tensile direction parallel to the rolling direction. Regarding the tensile test conditions, the test piece width is set to 12.5 mm, the measurement temperature is set to room temperature (15–35°C), the tensile speed is set to 5 mm/min, and the gauge length is set to 50 mm. Two test pieces can be used for the test, and the average of the two data points is taken as the tensile strength in the direction parallel to the rolling direction in this invention. The above tensile speed is equivalent to the crosshead displacement speed recorded in the JIS standard. As a tensile testing machine, the AUTO COM AC-100KN-C manufactured by TSE Corporation or an equivalent device can be used. Furthermore, by setting the composition of the copper alloy to the composition of the copper alloy described in this embodiment, the tensile strength in the direction parallel to the rolling direction can be kept within the desired range.

The copper alloy of this embodiment has a conductivity of 30% IACS or higher. With a conductivity of 30% IACS or higher, it can be effectively used as a copper alloy component for electronic devices. Conductivity refers to the conductivity in the direction parallel to the rolling direction. Furthermore, by setting the composition of the copper alloy as described above for the copper alloy of this embodiment, the conductivity can be made within the desired range. Conductivity (EC: %IACS) can be measured according to JIS-H0505 (1975) using the four-terminal method. Measurement can be performed using a double bridge, and resistance can be measured based on the average cross-sectional area method. Regarding conductivity, the conductivity in the direction parallel to the rolling direction can be measured at room temperature (25°C). Furthermore, for the convenience of testing samples, the gauge length (distance between resistance measurements) can be measured at 50 mm.

The following describes a method for manufacturing a copper alloy plate. In this embodiment, the copper alloy plate is not particularly limited and can be manufactured using a method that includes a rolling step. Specifically, the copper alloy plate can be manufactured by sequentially performing homogenization, hot rolling, intermediate cold rolling, solution treatment, aging treatment, fine cold rolling, and relaxation annealing on an ingot. Cold rolling before solution treatment is not necessary and can be performed as needed. Furthermore, cold rolling can be performed as needed after solution treatment and before aging treatment, or two or more solution treatments and aging treatments can be performed separately. After performing the above steps, appropriate methods such as grinding, polishing, bead blasting, and pickling can be used to remove surface oxide scale.

A more detailed example of a method for manufacturing a copper alloy plate using a method including a rolling step is provided. The method for manufacturing the copper alloy plate may include a step of first melting and casting a raw material of a copper alloy having the desired composition as described above. In this step, the raw material of the copper alloy is melted using a method similar to that used for melting conventional copper alloys, and then an ingot is manufactured by continuous casting or semi-continuous casting. For example, firstly, raw materials such as electrolytic copper, Ni, Co, Si, and Cr are melted using an atmospheric melting furnace to obtain a molten liquid with the desired composition. Then, the molten liquid is poured into a mold of any size to cast an ingot.

In this embodiment, the method for manufacturing the copper alloy plate may include a step of hot rolling an ingot that has undergone arbitrary homogenization annealing. The hot rolling of the ingot is not particularly limited; for example, it can be performed in several passes at 500–950°C. Furthermore, the overall machining degree of the hot rolling is preferably set to 90% or higher.

Solution treatment is a heat treatment process that dissolves silicides such as Ni-Si, Co-Si, and Ni-Co-Si compounds into a Cu matrix, simultaneously causing recrystallization of the Cu matrix. The heating temperature for solution treatment is not particularly limited; for example, it can be set to 650–1000°C. The heating time can be set to 1 second–10 minutes. Specifically, by setting the solution treatment temperature or time above the lower limit of the above range, even if the copper alloy contains a large amount of Ni-Co-Si compounds, they can be easily and fully dissolved in the Cu matrix, and recrystallization can be achieved. By setting the solution treatment temperature or time below the upper limit of the above range, the coarsening of recrystallized grains can be easily suppressed. The preferred heating temperature is 700–950°C, and the preferred time is 5 seconds to 5 minutes.

In this embodiment, the method for manufacturing the copper alloy plate may include an aging treatment step for the intermediate material after the aforementioned solution treatment. The heating temperature for the aging treatment is not particularly limited, but can be set to, for example, 375–625°C. Furthermore, the heating time can be set to 0.5–50 hours. By setting the aging temperature or time above the lower limit of the above range, the amount of Ni-Si compounds, Co-Si compounds, and Ni-Co-Si compounds precipitated becomes sufficient, making it easier to obtain sufficient strength. By setting the aging temperature or time below the upper limit of the above range, coarsening or re-solution of the precipitates can be prevented, making it easier to sufficiently improve strength or conductivity. To significantly improve the strength and conductivity of copper alloys, it is crucial to enhance the tensile strength and conductivity of the intermediate material after aging treatment in the direction parallel to the rolling direction. For example, to achieve a tensile strength of 870 MPa or higher for the copper alloy, the tensile strength of the intermediate material after aging treatment can be increased to 750 MPa or higher. Similarly, to achieve a tensile strength of 930 MPa or higher for the copper alloy, the tensile strength of the intermediate material after aging treatment can be increased to 830 MPa or higher. For instance, the conductivity of the intermediate material after aging treatment in the direction parallel to the rolling direction can be set to 40% IACS or higher. In order to inhibit the formation of oxide films, aging treatment is better performed in inactive environments such as Ar, _N2 , and _H2 .

In this embodiment, the manufacturing method of the copper alloy plate may include a step of fine cold rolling of the aforementioned intermediate material. Fine cold rolling is not particularly limited, and can be performed in several passes, for example. Preferably, it involves one or more rolling passes. The total machining percentage of the fine cold rolling is preferably 40% or higher. By imparting work strain to the material through fine cold rolling, the strength can be improved. The upper limit of the machining percentage of the fine cold rolling is preferably 90% or lower. By keeping the machining percentage below 90%, it is possible to prevent a decrease in conductivity due to work strain from intense processing. If the thickness of the workpiece used for rolling is TB, and the thickness of the workpiece after rolling is TA, then the machining percentage (%) is expressed as machining percentage (%) = [(TB - TA) / TB] × 100.

In this embodiment, the method for manufacturing the copper alloy plate may include a step of stress annealing of the intermediate material after the aforementioned fine cold rolling. Stress annealing can be performed under normal conditions, such as at 250°C to 550°C for a holding time of 5 seconds to 5 hours. Stress annealing can be performed in the atmosphere or in an inert environment such as nitrogen or argon. Furthermore, the copper alloy plate after stress annealing can also be cooled by air cooling.

In this embodiment, the copper alloy plate can be manufactured by a manufacturing method including the steps described above. Furthermore, in this manufacturing method, pickling, grinding, degreasing, face cutting, and finishing can be performed as needed after each rolling step or heat treatment step. Also, this manufacturing method may include rolling steps or heat treatment steps other than those described above.

[Electronic Components] The electronic component of this embodiment is an electronic component containing the copper alloy of this embodiment described above. More specifically, the electronic component of this embodiment has a copper alloy component internally manufactured from the copper alloy of this embodiment via a copper alloy plate. As an electronic component, it can be used as, for example, a semiconductor package. The miniaturized copper alloy component, which can be manufactured from the copper alloy of this embodiment, has the characteristic of suppressing deformation during the manufacturing process of the electronic component. Therefore, the copper alloy of this embodiment is suitable for manufacturing semiconductor packages with more miniaturized structures. Furthermore, when the electronic component is a semiconductor package, the semiconductor package is not particularly limited. For example, it can be manufactured by using a copper alloy plate made of the copper alloy of this embodiment to create a lead frame; then, supporting and fixing the semiconductor element to the lead frame; wire bonding the semiconductor element and leads to form internal wiring; and finally, sealing the semiconductor element with a specified resin component. As described above, the electronic component of this embodiment may also contain the copper alloy of this embodiment.

The above describes the embodiments of the present invention, but the copper alloys and electronic components of the present invention are not limited to the examples described above, and appropriate modifications may be made.

(State of the Invention) The first state of the invention is a copper alloy containing 2.3–4.6% by mass Ni, 0.10–0.50% by mass Co, 0.60–1.3% by mass Si, and 0.010–0.10% by mass Cr, with the remainder consisting of Cu and unavoidable impurities.

The second state of the present invention is a copper alloy as described in the first state, which contains less than 0.50% by mass of Co.

The third state of the present invention is a copper alloy as described in the first or second state, containing 0.10 to 0.40% by mass of Co.

The fourth state of the present invention is a copper alloy as described in any one of the first to third states, containing 0.20 to 0.30% by mass of Co.

The fifth state of the present invention is a copper alloy as described in any one of states 1 to 4, containing 0.020 to 0.070% by mass of Cr.

The sixth state of the present invention is a copper alloy as described in any one of the states 1 to 5, containing 3.0 to 4.0% by mass of Ni.

The seventh state of the present invention is a copper alloy as described in any one of the first to sixth states, wherein the mass ratio of the total mass of Ni and Co to Si, _RA, is 3.5 to 5.0.

The eighth aspect of the present invention is a copper alloy as described in the seventh aspect, wherein the ratio _RA is 3.5 to 4.5.

The ninth state of the present invention is a copper alloy as described in any one of states 1 to 8, wherein the mass ratio of Co to Ni, _RB, is 0.010 to 0.155.

The 10th aspect of this invention is a copper alloy as described in the 9th aspect, wherein the ratio _RB is 0.025 to 0.155.

The 11th aspect of this invention is a copper alloy as described in the 9th aspect, wherein the ratio _RB is 0.056 to 0.086.

The 12th state of the present invention is a copper alloy as described in any one of states 1 to 11, further containing a total of 0.010 to 1.0% by mass of one or more elements selected from the group consisting of Mg, Fe, P, Cr, Ag, Zn, Sn, Pb, Zr, Al, As, Se, Te, Sb, Bi, Au, Ti, Nb, V, Ta, W, Mo and Mn.

The 13th state of the present invention is a copper alloy as described in any of the 1st to 12th states, having a conductivity of 30% IACS or higher.

The 14th property of the present invention is a copper alloy as described in any one of the 1st to 13th properties, having a tensile strength of 870 MPa or more in a direction parallel to the rolling direction.

The 15th property of the present invention is a copper alloy as described in any of the 1st to 14th properties, having a tensile strength of 930 MPa or more in a direction parallel to the rolling direction.

The 16th aspect of this invention is an electronic component comprising a copper alloy as described in any one of aspects 1 through 15. [Example]

The present invention will now be described in detail by way of embodiments, but the present invention is not limited to any of the embodiments described below. In Embodiment 1, a copper alloy plate is manufactured from a desired copper alloy in the following manner: Electrolytic copper is used as raw material, and the copper alloy with the composition shown in Table 1 is melted and cast using an atmospheric melting furnace. The ingot is hot-rolled at 950°C until the plate thickness is 10.0 mm. After hot rolling, face cutting is performed, followed by intermediate cold rolling until the plate thickness is 0.167 mm. Then, solution treatment and aging treatment are performed under the conditions shown in Table 1, respectively. Next, fine cold rolling is performed with the machining degree shown in Table 1 until the plate thickness is 0.1 mm to obtain the copper alloy plate. Furthermore, in Embodiment 2, the copper alloy sheet of Embodiment 1, which underwent precision cold rolling, was then subjected to stress annealing in the atmosphere under the conditions shown in Table 2. The copper alloy sheet after stress annealing was cooled by air cooling, thereby obtaining the copper alloy sheet of Embodiment 2.

In Comparative Examples 1 and 2, the copper alloy plates were manufactured in the same manner as in Example 1, except that the composition of the copper alloy or the solution treatment conditions were changed to those shown in Table 1. Specifically, in Comparative Example 1, the composition of the copper alloy was changed to that shown in Table 1, and the solution treatment temperature was changed to 900°C or 925°C as shown in Table 1. Otherwise, two samples as copper alloy plates were manufactured using the same manufacturing method as in Example 1. Then, the evaluations of the copper alloy in Comparative Example 1 were plotted with the numerical values of the evaluation results of the two samples (as shown in Table 1, regarding the tensile strength or conductivity of the copper alloy sheet after aging treatment or fine cold rolling) on the vertical axis and the solution treatment temperature on the horizontal axis. The straight line connecting the plot was calculated and determined. Then, the value of the solution treatment temperature of 915°C was substituted into the formula representing the straight line, thereby obtaining the estimated evaluation results of the copper alloy and its intermediates when solution treatment was performed at 915°C. Furthermore, in Comparative Example 2, similar to Comparative Example 1, the composition of the copper alloy was changed to that shown in Table 1, and the solution treatment temperatures were changed to 910°C, 935°C, and 950°C as shown in Table 1. Apart from this, three samples as copper alloy plates were manufactured using the same manufacturing method as in Example 1. Then, the evaluations of the copper alloy in Comparative Example 2 were plotted with the evaluation results of the three samples on the vertical axis and the solution treatment temperature on the horizontal axis. An approximate straight line connecting the plot was calculated and determined (using the approximate straight line function of Microsoft Excel). Then, the value of the solution treatment temperature of 915°C was substituted into the formula representing the approximate straight line, thereby obtaining the estimated evaluation results of the copper alloy and its intermediates when solution treatment was performed at 915°C.

The copper alloy plates of Examples 1 and 2 and Comparative Examples 1 and 2 were subjected to the following measurements. The results are shown in Tables 1 and 2. [Composition] The composition of the obtained copper alloys was confirmed by fluorescent X-ray analysis. A Rigaku Simultix14 fluorescent X-ray analysis apparatus was used. The analysis surface was machined or mechanically ground to achieve a maximum surface roughness Rz (JIS-B0601 (2013)) of 6.3 μm or less. The fluorescent X-ray analysis was performed based on JIS K 0119:2008, using wavelength dispersion.

[Tensive Strength (TS)] The tensile strength (TS) of the obtained copper alloy plates was measured using a tensile testing machine in a direction parallel to the rolling direction, according to JIS-Z2241 (2011). Specifically, JIS 13B test pieces were prepared from each sample using a pressing machine with the stretching direction parallel to the rolling direction. Regarding the tensile test conditions, the test piece width was set to 12.5 mm, the measurement temperature was set to room temperature (15–35°C), the tensile speed (crosshead displacement speed) was set to 5 mm/min, and the gauge length was set to 50 mm. Two test pieces were used for the test, and the average values of the two data points are shown in Tables 1 and 2.

[Conductivity] Conductivity (EC: %IACS) is measured according to JIS-H0505 (1975) using the four-terminal method. The measurement uses a double bridge, and resistance is measured based on the average cross-sectional area method. Conductivity is measured at room temperature (25°C) in the direction parallel to the rolling direction. Furthermore, the gauge length (distance between resistance measurements) is measured at 50 mm.

[Table 1] Composition (mass %) Mass ratio R_{_A} (Ni+Co)/Si Mass ratio R _B Co/Ni Steps Characteristics of intermediates after aging treatment Characteristics of copper alloy plates after precision cold rolling Ni Co Si Cr Cu Solution treatment Timeliness processing Precision cold rolling Tensile strength (MPa) Conductivity (%IACS) Tensile strength (MPa) Conductivity (%IACS) Implementation Example 1 3.55 0.25 0.87 0.05 The remaining part 4.37 0.07 915℃, 1 minute 375~625℃ 0.5~50 hours Processing degree 40% 856 40.3 958 40.1 Comparative example 1 3.17 0.63 0.87 0.05 The remaining part 4.37 0.20 900℃ or 925℃, 1 minute 852 41.2 919 40.1 Comparative example 2 2.80 1.00 0.87 0.05 The remaining part 4.37 0.36 910℃, 935℃ or 950℃, 1 minute 832 42.2 911 41.1

[Table 2] Composition (mass %) Mass ratio R_{_A} (Ni+Co)/Si Mass ratio _RB Co/Ni Steps Characteristics of intermediates after aging treatment Characteristics of copper alloy plates Ni Co Si Cr Cu Solution treatment Timeliness processing Precision cold rolling Relaxation annealing Tensile strength (MPa) Conductivity (%IACS) Tensile strength (MPa) Conductivity (%IACS) Implementation Example 2 3.55 0.25 0.87 0.05 The remaining part 4.37 0.07 915℃ for 1 minute 375～625℃ 0.5～50 hours Processing degree 40% 300℃ for 3 hours 856 40.3 975 41.0

As shown in Tables 1 and 2, it can be seen that by manufacturing with the desired composition, high conductivity is achieved while tensile strength is simultaneously increased. Therefore, the miniaturized copper alloy parts for electronic components manufactured from the copper alloys of Examples 1 and 2 can suppress deformation during the manufacturing process of electronic components. The characteristics (tensile strength and conductivity) of the copper alloys of Example 1, Comparative Examples 1 and 2 are plotted against the Co content (mass%), and the results of plotting a linear approximate curve are shown in Figure 1. As the Co content increases, Co-Si precipitates or Ni-Co-Si precipitates are generated, thus the conductivity is considered to increase. Therefore, a linear approximate curve is plotted from the experimental values obtained in the examples to predict the conductivity at various Co contents. Based on these results, it can be seen that if the Co content is 0.10% by mass or more, a conductivity of 39.7% IACS or higher can be achieved. It can be seen that if the Co content is 0.20% by mass or more, a conductivity of 39.8% IACS or higher can be achieved. It can be seen that if the Co content is 0.25% by mass or more, a conductivity of 40.1% IACS or higher can be achieved. The properties (tensile strength and conductivity) of the copper alloys of Example 1, Comparative Examples 1 and 2 are plotted relative to the Co/Ni mass ratio _RB (Co/Ni (mass ratio)). The result of plotting a linear approximate curve is shown in Figure 2. With increasing _RB , Co-Si or Ni-Co-Si precipitates are formed; therefore, it is considered that conductivity is easily obtained but strength is difficult to obtain. Therefore, a linear approximate curve was constructed from the experimental values obtained in the embodiment to predict the strength and conductivity at each R_{_B}. According to the results, it can be seen that if the R_{_B} is 0.010 or higher, a conductivity of 39.7% IACS or higher can be achieved. It can be seen that if the R_{_B} is 0.025 or higher, a conductivity of 39.7% IACS or higher can be achieved. It can be seen that if the R_{_B} is 0.056 or higher, a conductivity of 39.8% IACS or higher can be achieved. Furthermore, it can be seen that if the R_{_B} is 0.155 or lower, a tensile strength of 938 MPa or higher can be achieved. It can be seen that if the R_{_B} is 0.086 or lower, a tensile strength of 949 MPa or higher can be achieved. [Industrial Applicability]

According to the present invention, a copper alloy with high conductivity and high strength and electronic components containing the same can be provided.

without

[Figure 1] is a graph plotting the properties of the copper alloys of Embodiment 1 and Comparative Examples 1 and 2 relative to the Co content (mass %), depicting a linear approximate curve. The first axis represents tensile strength, and the second axis represents conductivity. Squares represent tensile strength, and circles represent conductivity. [Figure 2] is a graph plotting the properties of the copper alloys of Embodiment 1 and Comparative Examples 1 and 2 relative to the Co to Ni mass ratio _RB , depicting a linear approximate curve. The first axis represents tensile strength, and the second axis represents conductivity. Squares represent tensile strength, and circles represent conductivity.

Claims (15)

A copper alloy containing 2.3 to 4.6% by mass of Ni, 0.10 to 0.50% by mass of Co, 0.60 to 1.3% by mass of Si, and 0.010 to 0.10% by mass of Cr, with the remainder consisting of Cu and unavoidable impurities, has a tensile strength of 870 MPa or more in a direction parallel to the rolling direction. For example, the copper alloy in claim 1 contains less than 0.50% by mass of Co. For example, the copper alloy in claim 2 contains 0.10 to 0.40% by mass of Co. For example, the copper alloy in claim 3 contains 0.20 to 0.30% by mass of Co. The copper alloy of any of the claims 1 to 4 contains 0.020 to 0.070% by mass of Cr. The copper alloy of any one of claims 1 to 4 contains 3.0 to 4.0% by mass of Ni. For any of the copper alloys in claims 1 to 4, the mass ratio of the total amount of Ni and Co to Si, _RA, is 3.5 to 5.0. For example, the copper alloy in claim 7, wherein the ratio _RA is 3.5 to 4.5. For example, in any of the copper alloys in claims 1 to 4, the mass ratio of Co to Ni, _RB, is 0.010 to 0.155. For example, in the copper alloy of claim 9, the ratio _RB is 0.025 to 0.155. For example, in the copper alloy of claim 9, the ratio _RB is 0.056 to 0.086. The copper alloy of any one of claims 1 to 4 further contains a total of 0.010 to 1.0% by mass of one or more elements selected from the group consisting of Mg, Fe, P, Cr, Ag, Zn, Sn, Pb, Zr, Al, As, Se, Te, Sb, Bi, Au, Ti, Nb, V, Ta, W, Mo and Mn. For example, the copper alloys in any of the requests 1 to 4 have a conductivity of 30% IACS or higher. The copper alloy of any of the claims 1 to 4 has a tensile strength of 930 MPa or more in the direction parallel to the rolling direction. An electronic component comprising a copper alloy of any one of claims 1 to 14.