Copper alloy sheet, electronic component, and method for producing copper alloy sheet

Abstract

The present invention provides: a copper alloy sheet which exhibits excellent heat resistance and has high hardness even after annealing; an electronic component; and a method for producing a copper alloy sheet. This copper alloy sheet contains 1.5-4.6 mass% of Ni, 0.10-0.80 mass% of Co, 0.10-1.30 mass% of Si, with the balance being made up of Cu and inevitable impurities. This copper alloy sheet has a Vickers hardness of 250 HV or more after being annealed at 450°C for 5 minutes.

Description

Copper alloy sheet, electronic component, and method for manufacturing copper alloy sheet

[0001] The present invention relates to a copper alloy sheet, an electronic component, and a method for manufacturing a copper alloy sheet.

[0002] Corson alloys are alloys in which intermetallic compounds such as Ni-Si, Co-Si, and Ni-Co-Si are precipitated in a Cu matrix. Corson alloys are used in electronic components because they have both high strength and high electrical conductivity. For example, they can be used as lead frames that support and fix semiconductor elements in semiconductor packages and form internal wiring (see, for example, Patent Document 1).

[0003] JP 2018-035437 A

[0004] Lead frames are manufactured, for example, by pressing a copper alloy sheet. Short-term annealing may be performed to reduce residual stress generated by pressing. Annealing may reduce the hardness of the copper alloy sheet. The invention described in Patent Document 1 aims to improve the strength and the surface smoothness of the etched surface, but does not adequately address the reduction in hardness associated with a decrease in heat resistance after annealing.

[0005] In view of the above problems, the present invention provides a copper alloy sheet having excellent heat resistance and high hardness even after annealing, an electronic component, and a method for manufacturing the copper alloy sheet.

[0006] In order to solve the above problems, according to one embodiment of the present invention, a copper alloy sheet containing 1.50 to 4.60 mass% Ni, 0.10 to 0.80 mass% Co, 0.10 to 1.30 mass% Si, and the balance being Cu and inevitable impurities, is provided, wherein the copper alloy sheet has a Vickers hardness of 250 HV or more after annealing at 450 ° C. for 5 minutes.

[0007] According to another embodiment of the present invention, there is provided an electronic component comprising the above copper alloy sheet.

[0008] According to yet another embodiment of the present invention, a method for producing a copper alloy sheet is provided, comprising the steps of: hot-rolling an ingot of a copper alloy containing 1.50 to 4.60 mass% Ni, 0.10 to 0.80 mass% Co, 0.10 to 1.30 mass% Si, with the balance being Cu and inevitable impurities; solution-treating the obtained copper alloy intermediate; aging the copper alloy intermediate; finish-cold-rolling the copper alloy intermediate; and stress-relief annealing the copper alloy intermediate, in this order. The copper alloy intermediate after the solution-treating step and before the aging step has a tensile strength A (MPa), a 0.2% proof stress B (MPa), and an electrical conductivity C (% IACS) of the copper alloy intermediate, the following relational formula (1): X = (A × B) / C ... (1). The method comprises producing the copper alloy intermediate so that the value of X represented by the formula is 582 or more.

[0009] According to the present invention, it is possible to provide a copper alloy sheet, an electronic component, and a method for producing a copper alloy sheet, which have excellent heat resistance and high hardness even after annealing.

[0010] FIG. 1 is a graph showing the relationship between X, which is expressed by the relational formula (1): X=(A×B) / C, using the tensile strength (A), 0.2% proof stress (B), and electrical conductivity (C), for an intermediate copper alloy sheet after solution treatment and before aging treatment, and the hardness HV after annealing the copper alloy sheet at 450° C. for 5 minutes.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail, but the present invention is not limited to the following embodiments.

[0012] (Copper alloy sheet) The copper alloy sheet according to this embodiment is a copper alloy sheet containing 1.50 to 4.60 mass% Ni, 0.10 to 0.80 mass% Co, 0.10 to 1.30 mass% Si, with the balance being Cu and inevitable impurities. That is, the copper alloy sheet according to this embodiment is a Cu—Ni—Co—Si based alloy sheet.

[0013] (Contents of Ni, Co, and Si) Ni, Co, and Si form precipitated particles of a Cu-Ni-Co-Si intermetallic compound by appropriate heat treatment, thereby improving the electrical conductivity, strength, and heat resistance of the copper alloy.

[0014] The greater the amount of Ni added, the higher the strength, but the lower the conductivity tends to be. If the Ni concentration is less than 1.50 mass%, the desired strength cannot be obtained. The Ni concentration is preferably 2.00 mass% or more, more preferably 2.30 mass% or more, even more preferably 3.00 mass% or more, and even more preferably 3.50 mass% or more. On the other hand, if the Ni concentration exceeds 4.60 mass%, the desired conductivity cannot be obtained. The Ni concentration is preferably 4.50 mass% or less, more preferably 4.30 mass% or less, even more preferably 4.00 mass% or less, and even more preferably 3.70 mass% or less.

[0015] If the Si concentration is less than 0.10 mass%, the desired strength cannot be obtained. The Si concentration is preferably 0.30 mass% or more, more preferably 0.50 mass% or more, even more preferably 0.70 mass% or more, and even more preferably 0.80 mass% or more. On the other hand, if the Si concentration is more than 1.30 mass%, the desired conductivity cannot be obtained. The Si concentration is preferably 1.20 mass% or less, more preferably 1.10 mass% or less, even more preferably 1.00 mass% or less, and even more preferably 0.90 mass% or less.

[0016] Co improves electrical conductivity and strength, and by adding an appropriate amount, it is possible to suppress a decrease in the heat resistance of the copper alloy sheet according to this embodiment, which is caused by short-time annealing when reducing residual stress after press working after press working the copper alloy sheet into a desired electronic component such as a lead frame. In order to obtain a copper alloy sheet that combines high electrical conductivity, high strength, and the effect of improving heat resistance against short-time annealing after working, the Co concentration is set to 0.10 mass% or more. The Co concentration is preferably 0.15 to 0.80 mass%, more preferably 0.15 to 0.70 mass%, even more preferably 0.20 to 0.50 mass%, and even more preferably 0.20 to 0.40 mass%.

[0017] (Ni + Co) If the content of Ni + Co is too low, the desired strength, electrical conductivity, and heat resistance improvement effect for short-time annealing after heat treatment cannot be significantly obtained, while if the amount of Ni + Co added is too large, workability deteriorates. The copper alloy sheet according to this embodiment preferably contains Ni and Co in total at 1.60 mass% or more, more preferably at 2.28 mass% or more, even more preferably at 3.00 mass% or more, and even more preferably at 3.50 mass% or more. On the other hand, the copper alloy sheet according to this embodiment preferably contains Ni and Co in total at 4.50 mass% or less, more preferably at 4.30 mass% or less, and even more preferably at 4.00 mass% or less. The ratio of Co to Ni is preferably 0.05 to 0.10, more preferably at 0.05 to 0.09, and even more preferably at 0.05 to 0.08.

[0018] ((Ni + Co) / Si mass ratio) Ni-Co-Si-based precipitates formed from Ni, Co, and Si are considered to be intermetallic compounds mainly composed of (Ni + Co) Si. However, not all of the Ni, Co, and Si in the copper alloy sheet become precipitates by the aging treatment during the manufacturing process of the copper alloy sheet, and some may exist in a solid solution state in the Cu matrix. Ni, Co, and Si in a solid solution state can improve the strength of the copper alloy sheet, but the effect is smaller than that in a precipitated state, and they may also be a factor in reducing the electrical conductivity. Therefore, it is preferable that the contents of Ni, Co, and Si are close to the composition ratio of (Ni + Co) Si. In the copper alloy sheet according to this embodiment, the mass ratio of the total of Ni and Co to Si ((Ni + Co) / Si) is preferably 3.4 to 5.4, more preferably 3.8 to 5.0, and even more preferably 4.0 to 4.5.

[0019] (Additive elements) At least one element 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 (also referred to as "additive elements" in this specification) improves manufacturability by refining the ingot structure, such as improving hot workability, and also has the effect of improving the strength, electrical conductivity, and heat resistance of the copper alloy sheet. Therefore, by adding one or more of these additive elements according to the properties required of the copper alloy sheet according to this embodiment, further improvement in the properties of the copper alloy sheet can be expected.

[0020] The copper alloy sheet according to this embodiment preferably further contains 0.01 to 2.00 mass% in total 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 total content of the additional elements is preferably 0.03 to 1.00 mass%, more preferably 0.05 to 0.50 mass%.

[0021] (Cr Content) Among the additive elements, Cr precipitates alone or as a compound with Si in the copper matrix by appropriate heat treatment, thereby improving hot rolling properties. It also has the effect of improving the strength, electrical conductivity, and heat resistance of the copper alloy sheet according to this embodiment. On the other hand, if the Cr content exceeds 0.500 mass%, coarse inclusions that do not contribute to strengthening are formed, which may impair workability. The copper alloy sheet according to this embodiment can contain 0.05 to 0.50 mass%, preferably 0.01 to 0.50 mass%, more preferably 0.20 to 0.50 mass%, and even more preferably 0.20 to 0.30 mass% of Cr in the Cu-Ni-Co-Si alloy.

[0022] (Mg Content) Among the additive elements, when an appropriate amount of Mg is contained, it not only stably forms precipitated particles of Si contained in the copper alloy sheet according to this embodiment, but also has the effect of obtaining a copper alloy sheet that combines strength, electrical conductivity, and heat resistance. The copper alloy sheet according to this embodiment can contain 0.005 to 0.50 mass%, preferably 0.01 to 0.50 mass%, more preferably 0.05 to 0.50 mass%, and even more preferably 0.10 to 0.30 mass% of Mg in the Cu-Ni-Co-Si alloy.

[0023] The copper alloy sheet according to this embodiment is made up of Cu and inevitable impurities, the remainder being components other than those mentioned above. Here, the inevitable impurities refer to impurity elements that are unavoidably mixed into the copper alloy sheet during the manufacturing process. The concentration of each element of the inevitable impurities can be, for example, less than 0.001 mass%, and preferably 0% (undetectable).

[0024] The composition of the copper alloy can be measured using X-ray fluorescence analysis. The X-ray fluorescence analyzer used can be a Simultix 14 manufactured by Rigaku Corporation or an equivalent device. The analysis surface can be machined or mechanically polished so that the maximum surface roughness Rz (JIS B 0601:2013) is 6.3 μm or less. When collecting samples for X-ray fluorescence analysis from the molten metal during melting and casting, the sample is cast into a shape of approximately 30 to 40 mm diameter and 50 to 80 mm thick, then cut to a thickness of approximately 10 to 20 mm, and the cut surface is used as the analysis surface. X-ray fluorescence analysis is performed based on JIS K 0119:2008, and measurements are taken using a wavelength dispersive method.

[0025] The composition of copper alloys can also be measured by wet analysis. Ni may be determined using the copper-separated dimethylglyoxime nickel gravimetric method (JIS H1056:2003), and Si may be determined using the silicon dioxide gravimetric method (JIS H1061:2006). Other additive elements and impurity elements may be determined using ICP atomic emission spectroscopy. Analysis of other additive elements is performed using an internal standard method, with Y (yttrium) used as the internal standard. An element other than Y may also be selected as the internal standard. ICP atomic emission spectroscopy is performed using a Hitachi High-Tech Science Corporation ICP atomic emission spectroscopy analyzer (ICP-OES) SPS3100 or an equivalent device. For ICP atomic emission spectroscopy, a copper alloy sample is dissolved in a mixed acid containing hydrochloric acid and nitric acid (containing hydrochloric acid, nitric acid, and water in a volume ratio of 2:1:2), and then diluted.

[0026] The shape of the copper alloy sheet according to this embodiment is not particularly limited as long as it is a three-dimensional shape having a predetermined thickness. The "plate" of the copper alloy sheet also includes sheet, strip, and foil. Furthermore, the copper alloy sheet according to this embodiment includes not only copper alloy sheets before processing for use in electronic components, but also copper alloy sheets during or after processing. The thickness of the copper alloy sheet is, for example, 0.03 to 1.2 mm. The thickness is preferably 0.03 to 0.60 mm, and more preferably 0.08 to 0.30 mm.

[0027] (Vickers hardness) The copper alloy sheet according to this embodiment has a Vickers hardness of 250 HV or more after annealing the copper alloy sheet at 450°C for 5 minutes. When a copper alloy sheet is processed by pressing, residual stress may occur in the copper alloy sheet. In order to reduce this residual stress, short-term annealing may be performed, but if the heat resistance of the copper alloy sheet is low due to this annealing, the copper alloy sheet may soften and deform after processing. The copper alloy sheet according to this embodiment has heat resistance to short-term annealing for reducing residual stress, so that deformation is unlikely to occur even after short-term annealing is performed after processing the copper alloy sheet, and the target Vickers hardness can be achieved.

[0028] In one embodiment, the copper alloy according to this embodiment preferably has a Vickers hardness of 262 HV or more, more preferably 280 HV or more, and preferably 290 HV or more after annealing the copper alloy sheet at 450 ° C. for 5 minutes. The upper limit of the Vickers hardness after annealing the copper alloy sheet at 450 ° C. for 5 minutes is not particularly limited, but may be 350 HV or less, 320 HV or less, or 300 HV or less. Specifically, the copper alloy according to this embodiment may have a Vickers hardness of 262 to 350 HV, further 280 to 350 HV, or even 290 to 320 HV after annealing the copper alloy sheet at 450 ° C. for 5 minutes.

[0029] The Vickers hardness of the copper alloy sheet can be measured in accordance with JIS Z 2244-1:2020 by the method described in the Examples section below. The Vickers hardness of the copper alloy sheet after annealing can be controlled to a desired range by controlling the composition of the copper alloy sheet within the above range and manufacturing it by the manufacturing method described below. The Vickers hardness value can be adjusted to be larger by, for example, increasing the value of X in formula (1) in the manufacturing method described below.

[0030] (Tensile strength) The copper alloy sheet according to this embodiment may have a tensile strength of 870 MPa or more in a direction parallel to the rolling direction. A tensile strength of 870 MPa or more can suppress deformation of the copper alloy sheet when electronic components are manufactured using the copper alloy sheet. The copper alloy sheet according to this embodiment more preferably has a tensile strength of 930 MPa or more in a direction parallel to the rolling direction. The upper limit of the tensile strength in the direction parallel to the rolling direction is not particularly limited, but the tensile strength may be, for example, 1200 MPa or less or 1100 MPa or less. The copper alloy sheet according to this embodiment may have a tensile strength in a direction perpendicular to the rolling direction of preferably 900 MPa or more, more preferably 950 MPa, and even more preferably 977 MPa or more. The tensile strength of the copper alloy sheet can be measured in accordance with JIS Z 2241:2011 by the method described in the Examples section below.

[0031] (0.2% Yield Strength) The copper alloy sheet according to this embodiment may have a 0.2% yield strength of 850 MPa or more in a direction parallel to the rolling direction. This makes it possible to more effectively suppress deformation of the copper alloy sheet during the manufacture of electronic components. The 0.2% yield strength in a direction parallel to the rolling direction is preferably 870 MPa or more, more preferably 900 MPa or more, and even more preferably 936 MPa or more. The upper limit of the 0.2% yield strength in a direction parallel to the rolling direction is not particularly limited, but the 0.2% yield strength may be, for example, 1200 MPa or less, 1100 MPa or less, or 1000 MPa or less. The 0.2% yield strength can be measured in accordance with JIS Z 2241:2011 by the method described in the Examples section below.

[0032] (Electrical Conductivity) The copper alloy sheet according to this embodiment may have an electrical conductivity of 35.0% IACS or more. With an electrical conductivity of 35.0% IACS or more, the copper alloy sheet can be effectively used as a copper alloy part for electronic components. The electrical conductivity is preferably 37.0% IACS or more, more preferably 40.0% IACS or more, and even more preferably 40.2% IACS or more. The upper limit of the electrical conductivity is not particularly limited, but may be, for example, 90.0% IACS or less, or 80.0% IACS or less.

[0033] The electrical conductivity can be measured by the four-terminal method in accordance with JIS H 0505:1975. A double bridge is used for the measurement, and the resistance can be measured based on the average cross-sectional area method. The electrical conductivity can be measured at room temperature (25°C) in a direction parallel to the rolling direction. The gage length (distance between electrical resistance measurements) can be 50 mm.

[0034] (Method for manufacturing copper alloy sheet) Hereinafter, a method for manufacturing a copper alloy sheet according to this embodiment will be described. The method for manufacturing a copper alloy sheet according to this embodiment includes the steps of hot-rolling an ingot of a copper alloy containing 1.50 to 4.60 mass% Ni, 0.10 to 0.80 mass% Co, 0.10 to 1.30 mass% Si, with the balance being Cu and inevitable impurities, solution-treating the obtained copper alloy intermediate, aging-treating the copper alloy intermediate, finish-cold-rolling the copper alloy intermediate, and stress-relief annealing the copper alloy intermediate, in this order, and also includes manufacturing a copper alloy intermediate such that the value of X, represented by the following relational expression: X = (A × B) / C ... (1), is 582 or more for the tensile strength A (MPa), 0.2% proof stress B (MPa), and electrical conductivity C (% IACS) of the copper alloy intermediate after the solution-treating step and before the aging step. According to the method for producing a copper alloy sheet according to this embodiment, attention is paid to the heat resistance of the copper alloy sheet after forming, and by adjusting the production conditions so that the value of X in formula (1) is 582 or more during the production of a copper alloy intermediate, a copper alloy can be obtained that is resistant to a decrease in hardness even after the copper alloy sheet is formed into a predetermined shape and then annealed for a short time.

[0035] Specifically, the copper alloy sheet according to this embodiment can be manufactured by the following method. First, a step of melting and casting a copper alloy raw material having the desired composition described above is performed. In this step, the copper alloy raw material is melted using a method similar to that of a general copper alloy melting method, and then an ingot is produced by continuous casting, semi-continuous casting, or the like. That is, an atmospheric melting furnace is used to melt raw materials such as electrolytic copper, Ni, Co, and Si to obtain a molten metal with the desired composition. This molten metal is then poured into a mold of any desired size to cast an ingot. Thereafter, homogenization annealing is performed at 800 to 1000°C, and further hot rolling is performed.

[0036] Hot rolling is performed in several passes at, for example, 500 to 900°C. The total reduction ratio of the hot rolling is preferably 90% or more. The reduction ratio (%) of the rolling is expressed as reduction ratio (%) = [(TB - TA) / TB] x 100, where TB is the thickness of the workpiece before rolling and TA is the thickness of the workpiece after rolling.

[0037] In the solution treatment after hot rolling, silicides (silicides) such as Ni-Si compounds, Co-Si compounds, and Cr-Si compounds are dissolved in the Cu matrix, and at the same time, heat treatment is performed to recrystallize the Cu matrix. In the method for producing a copper alloy sheet according to this embodiment, by adjusting the value of X in formula (1) of the copper alloy intermediate after the solution treatment to be 582 or more, a copper alloy sheet and electronic parts having excellent heat resistance and a high hardness of 250 HV or more even after annealing can be obtained.

[0038] The value of X represented by formula (1) is preferably 3000 or more, more preferably 5000 or more, and even more preferably 8000 or more. The upper limit of X is not particularly limited, but is typically preferably 17000 or less, more preferably 15000 or less, and even more preferably 13000 or less. By adjusting the value of X in formula (1) to a large value, the Vickers hardness value after annealing the copper alloy sheet at 450 ° C. for 5 minutes can be made larger.

[0039] FIG. 1 is a graph showing the relationship between X in the above formula (1) and the Vickers hardness (HV) of a copper alloy sheet after stress relief annealing (described later) at 450 ° C. for 5 minutes. Here, the tensile strength (A), 0.2% proof stress (B), and electrical conductivity (C) are all values ​​obtained by measuring in a direction parallel to the rolling direction. By setting the value of X in formula (1) to 582 or more, a copper alloy sheet having excellent heat resistance and high hardness even after annealing can be obtained. Note that the values ​​of electrical conductivity (A (% IACS)), 0.2% proof stress (B (MPa)), and tensile strength (C (MPa)) of the copper alloy intermediate after solution treatment in formula (1) can be measured by the method described in the Examples section below.

[0040] In this embodiment, in order to improve the heat resistance of the copper alloy sheet, the value of X in the solution treatment step is adjusted by adjusting the heating temperature, material temperature, heating time, etc. during the solution treatment. The heating temperature during the solution treatment can be appropriately selected from the range of 800 to 1100°C, for example. The heating temperature during the solution treatment may be 900 to 1100°C, or may be 950 to 1100°C. The material temperature can be appropriately selected from the range of 750 to 950°C, for example. After the solution treatment, the material temperature is slowly cooled to 400 to 500°C. The heating time can be appropriately selected from the range of 1 second to 10 minutes. By setting the heating temperature and material temperature during the solution treatment relatively high in the range of 800 to 1100°C and setting the heating time in the range of 1 second to 10 minutes, the value of X in formula (1) can be adjusted to 582 or more.

[0041] By appropriately selecting and combining the heating temperature, material temperature, heating time, etc. during the solution treatment, it is possible to dissolve the Ni-Co-Si compound in the Cu matrix and simultaneously recrystallize the Cu matrix, and during the aging treatment, precipitates that contribute to hardness are appropriately precipitated, thereby increasing the strength, electrical conductivity, and heat resistance. This makes it possible to increase the Vickers hardness of the copper alloy after stress relief annealing at 450°C for 5 minutes.

[0042] The heating temperature of the aging treatment for the copper alloy intermediate after the solution treatment may be, for example, 375 to 625°C, 400 to 550°C, or 450 to 500°C. The heating time of the aging treatment may be 1 to 50 hours, 1.5 to 25 hours, or 10 to 15 hours. By appropriately adjusting the heating temperature and heating time of the aging treatment, the amount of precipitated Ni-Co-Si compounds becomes sufficient, the desired strength is obtained, coarsening of the precipitates and re-dissolution can be prevented, strength and electrical conductivity can be easily improved, and heat resistance can be improved. The aging treatment is preferably performed in an inert atmosphere such as Ar, N2, or H2 to suppress the formation of an oxide film.

[0043] The finish cold rolling after the aging treatment may be performed in several passes. The total reduction ratio of the finish cold rolling may be 40% or more. This allows the copper alloy intermediate to be subjected to processing strain and improve its strength. By setting the total reduction ratio of the finish cold rolling to 40% or more, it is possible to improve the strength in various directions relative to the rolling direction. The reduction ratio of the finish cold rolling is preferably 55% or more, and more preferably 60% or more. The reduction ratio of the finish cold rolling may be 90% or less. This prevents a decrease in electrical conductivity due to processing strain caused by a high reduction ratio.

[0044] After the finish cold rolling, a step of performing stress relief annealing may be included. The heating temperature of stress relief annealing may be, for example, 300 to 600°C, preferably 400 to 600°C, and more preferably 420 to 550°C. The heating time of stress relief annealing may be, for example, 5 to 900 seconds, or 200 to 650 seconds. Stress relief annealing may be performed in air or in an inert atmosphere such as nitrogen or argon gas. Furthermore, the copper alloy sheet after stress relief annealing may be cooled by air cooling.

[0045] In the method for producing a copper alloy sheet according to this embodiment, cold rolling may be performed before the solution treatment, or after the solution treatment but before the aging treatment, or the solution treatment and the aging treatment may each be performed two or more times. Furthermore, after each of the above production steps, grinding, pickling, polishing, degreasing, facing, shot blasting, trimming, etc. may be appropriately performed as necessary to remove oxide scale from the surface.

[0046] Furthermore, the method for manufacturing a copper alloy sheet according to this embodiment may include a step of annealing the copper alloy sheet after the stress relief annealing step at 300°C or higher for 1 second or more. In particular, by carrying out this annealing step after performing processing such as pressing on the copper alloy sheet after the stress relief annealing step, residual stress in the copper alloy sheet generated by processing can be reduced. The copper alloy sheet after processing that has been subjected to such processing is less likely to deform and has both high electrical conductivity and strength.

[0047] The heating temperature in this annealing step may be 300 to 600° C., or 400 to 500° C. The heating time may be 1 second to 60 minutes, 30 seconds to 20 minutes, or 1 minute to 10 minutes.

[0048] (Electronic component) The electronic component of this embodiment is an electronic component including the copper alloy sheet according to this embodiment. More specifically, the electronic component according to this embodiment includes a copper alloy part manufactured from the above-mentioned copper alloy sheet. An example of the electronic component is a semiconductor package. The miniaturized copper alloy part that can be manufactured from the copper alloy sheet according to this embodiment has improved hardness after processing in the manufacturing process of the electronic component, and therefore it is suitable to use the copper alloy sheet according to this embodiment for manufacturing a semiconductor package having many miniaturized structures.

[0049] When the electronic component is a semiconductor package, the semiconductor package can be manufactured, for example, without being particularly limited thereto, by manufacturing a lead frame using the copper alloy sheet according to this embodiment, then supporting and fixing a semiconductor element on the lead frame, wire-bonding the semiconductor element to the leads to form internal wiring, and then sealing the semiconductor element with a predetermined resin member. As described above, the electronic component of this embodiment may include the copper alloy sheet of the above-mentioned embodiment.

[0050] Although the embodiments of the present disclosure have been described in detail above, the copper alloy sheet, electronic component, and method for manufacturing a copper alloy sheet according to the present disclosure are not limited to the above examples and can be modified as appropriate.

[0051] (Aspects of the Present Disclosure) A first aspect of the present disclosure is a copper alloy sheet containing 1.50 to 4.60 mass% Ni, 0.10 to 0.80 mass% Co, 0.10 to 1.30 mass% Si, and the balance being Cu and unavoidable impurities, wherein the copper alloy sheet has a Vickers hardness of 250 HV or more after annealing at 450°C for 5 minutes.

[0052] A second aspect of the present disclosure is the copper alloy sheet according to the first aspect, further containing 0.01 to 2.00 mass% in total 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.

[0053] A third aspect of the present disclosure is the copper alloy sheet according to the first or second aspect, further containing 0.01 to 0.50 mass% of Cr.

[0054] A fourth aspect of the present disclosure is the copper alloy sheet according to any one of the first to third aspects, containing 0.20 to 0.50 mass% Co.

[0055] A fifth aspect of the present disclosure is the copper alloy sheet according to any one of the first to fourth aspects, containing Ni and Co in total at 1.60 mass% or more.

[0056] A sixth aspect of the present disclosure is the copper alloy sheet according to any one of the first to fifth aspects, containing Ni and Co in total at 2.28 mass% or more.

[0057] A seventh aspect of the present disclosure is the copper alloy sheet according to any one of the first to sixth aspects, containing Ni and Co in total at 4.50 mass% or less.

[0058] An eighth aspect of the present disclosure is the copper alloy sheet according to any one of the first to seventh aspects, having a Vickers hardness of 262 HV or more.

[0059] A ninth aspect of the present disclosure is the copper alloy sheet according to any one of the first to eighth aspects, wherein the Vickers hardness is 350 HV or less.

[0060] A tenth aspect of the present disclosure is the copper alloy sheet according to any one of the first to ninth aspects, wherein the tensile strength in a direction parallel to the rolling direction is 870 MPa or more.

[0061] An eleventh aspect of the present disclosure is the copper alloy sheet according to any one of the first to tenth aspects, wherein the tensile strength in a direction parallel to the rolling direction is 930 MPa or more.

[0062] A twelfth aspect of the present disclosure is the copper alloy sheet according to any one of the first to eleventh aspects, having a conductivity of 35.0% IACS or more.

[0063] A thirteenth aspect of the present disclosure is the copper alloy sheet according to any one of the first to twelfth aspects, having a conductivity of 40.2% IACS or more.

[0064] A fourteenth aspect of the present disclosure is an electronic component including the copper alloy sheet according to any one of the first to thirteenth aspects.

[0065] A fifteenth aspect of the present disclosure is a method for producing a copper alloy sheet, comprising the steps of: hot-rolling an ingot of a copper alloy containing 1.50 to 4.60 mass% Ni, 0.10 to 0.80 mass% Co, 0.10 to 1.30 mass% Si, with the balance being Cu and inevitable impurities; solution-treating the obtained copper alloy intermediate; aging-treating the copper alloy intermediate; finish-cold-rolling the copper alloy intermediate; and stress-relief annealing the copper alloy intermediate, in this order, wherein the copper alloy intermediate after the solution-treating step and before the aging-treating step has a tensile strength A (MPa), a 0.2% proof stress B (MPa), and an electrical conductivity C (% IACS) as expressed by the following relational formula (1): X = (A × B) / C ... (1). The method includes producing a copper alloy intermediate so that the value of X is 582 or more.

[0066] A sixteenth aspect of the present disclosure is the method for producing a copper alloy sheet according to the fifteenth aspect, comprising annealing the copper alloy sheet after the stress relief annealing step at 300 ° C. or more for 1 second or more.

[0067] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to the following examples.

[0068] Using electrolytic copper as a raw material, copper alloys according to Examples and Comparative Examples having the compositions shown in Table 1 were melted and cast using an atmospheric melting furnace. The resulting ingots were subjected to homogenization annealing at 980°C for 25 minutes. Next, the ingots were hot rolled to a thickness of 10 mm, followed by facing. Then, solution treatment and aging treatment were performed in this order under the conditions shown in Table 1. Next, the resulting intermediates were pickled and polished, and then subjected to finish cold rolling to a thickness of 0.151 mm with the working ratio shown in Table 1. Next, stress relief annealing was performed in the atmosphere under the conditions shown in Table 1. The copper alloy sheets after stress relief annealing were air-cooled to obtain copper alloy sheets of Example 1 and Comparative Example 1.

[0069]

[0070] The physical properties of the obtained copper alloy sheets of Example 1 and Comparative Example 1 were measured by the following methods. The measurement results are shown in Table 2.

[0071] (Composition) The compositions of the obtained copper alloys were confirmed by X-ray fluorescence analysis. A Simultix 14 manufactured by Rigaku Corporation was used as the X-ray fluorescence analyzer. The copper alloy sheets of Example 1 and Comparative Example 1 were cut or mechanically polished to have a maximum surface roughness Rz (JIS B 0601:2013) of 6.3 μm or less, and the analysis surfaces were used. X-ray fluorescence analysis was performed based on JIS K 0119:2008, and measurements were made using a wavelength dispersive method.

[0072] (Tensile Strength) The tensile strength in the direction parallel to the rolling direction was measured using a tensile testing machine (Autocom AC-100KN-C, manufactured by TSE Co., Ltd.) in accordance with JIS Z 2241:2011. Specifically, a JIS Z 2241 No. 13B test piece was prepared from each sample using a press so that the tensile direction was parallel to the rolling direction. The tensile test conditions were as follows: test piece width: 12.5 mm, measurement temperature: room temperature (15 to 35°C), tensile speed (crosshead displacement speed): 5 mm / min, and gauge length (gauge length): 50 mm. The test was performed using two test pieces, and the average of the two data was calculated.

[0073] (0.2% Proof Stress) The 0.2% proof stress in the direction parallel to the rolling direction was measured using a tensile testing machine (Autocom AC-100KN-C, manufactured by TSE Co., Ltd.) in accordance with JIS Z 2241:2011 (offset method, 0.2%). Specifically, test pieces were prepared in the same manner as for the tensile strength described above, and tests were conducted under the same conditions as for the tensile strength described above.

[0074] (Conductivity) The conductivity was measured by a four-terminal method in accordance with JIS H 0505:1975. A double bridge was used for the measurement, and the resistance was measured based on the average cross-sectional area method. The conductivity was measured at room temperature (25°C) in a direction parallel to the rolling direction. The gage length (distance between electrical resistance measurements) was 50 mm.

[0075] (Elongation) Elongation was measured by conducting a tensile test in accordance with JIS Z 2241:2011. Test specimens were No. 5 or No. 13B test specimens specified in JIS Z 2241:2011, taken in a direction parallel to the rolling direction, with a gauge length of 50 mm. The measurement conditions for the tensile test were the same as those for measuring tensile strength described above. The length of the test specimen after fracture was measured by applying a caliper to the gauge length. The elongation was measured using the following formula: "Fracture elongation (%) = (final gauge length - original gauge length) ÷ original gauge length × 100". The definitions of the final gauge length and the original gauge length were the same as those in JIS-Z2241 (2011).

[0076] (Hardness after annealing) In accordance with JIS Z 2244-1:2020, the copper alloy sheets of Example 1 and Comparative Example 1 were annealed for 5 minutes at 450°C in a nitrogen atmosphere in a tubular furnace. The annealed copper alloy sheets were cooled to room temperature by air cooling. The Vickers hardness of the cooled copper alloy sheets was measured using a Vickers hardness tester. The Vickers hardness tester used was a Mitutoyo HM-103. The copper alloy sheets were cut into 20 mm x 20 mm pieces, embedded in resin, mechanically polished, and the thickness center of the rolled parallel cross section of the sample was measured. When embedding the resin, an epoxy resin (Epikote #828) manufactured by Mitsubishi Chemical Corporation was used as the resin, and a curing agent (Acmex H-89) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. was used as the curing agent, and these were heated to 100°C for 60 minutes to harden. The test force was 490.3 mN, the indenter approach speed was 60 μm / s, and the holding time was 15 seconds. The average value of the values ​​measured at three points was calculated. A 50x objective lens was used for the measurement, and the indentations were spaced at least 3d apart from the average diagonal length d of the indentations.

[0077]

[0078] According to Example 1, compared with Comparative Example 1, a copper alloy material having an excellent balance of strength, electrical conductivity and heat resistance and having a hardness after annealing suitable for use in electronic parts can be obtained.

[0079] (Potential Contribution to SDGs) According to one embodiment of the present disclosure, a copper alloy sheet having excellent heat resistance and high strength even after annealing, and an electronic component including the same, can be provided, which may contribute to improving the operational stability and reliability of electronic devices. Therefore, one embodiment of the present disclosure may contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation."

Claims

1. A copper alloy sheet containing 1.50 to 4.60 mass% Ni, 0.10 to 0.80 mass% Co, 0.10 to 1.30 mass% Si, with the balance being Cu and unavoidable impurities, wherein the copper alloy sheet has a Vickers hardness of 250 HV or more after annealing at 450°C for 5 minutes.

2. The copper alloy sheet according to claim 1, further containing 0.01 to 2.00 mass% in total 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.

3. The copper alloy sheet according to claim 1, further containing 0.01 to 0.50 mass% of Cr.

4. The copper alloy sheet according to claim 1, containing 0.20 to 0.50 mass % Co.

5. The copper alloy sheet according to claim 1, containing Ni and Co in a total amount of 1.60 mass% or more.

6. The copper alloy sheet according to claim 1, containing Ni and Co in a total amount of 2.28 mass% or more.

7. The copper alloy sheet according to claim 1, containing Ni and Co in a total amount of 4.50 mass% or less.

8. The copper alloy sheet according to claim 1, wherein the Vickers hardness is 262 HV or more.

9. The copper alloy sheet according to claim 1, wherein the Vickers hardness is 350 HV or less.

10. The copper alloy sheet according to claim 1, having a tensile strength in a direction parallel to the rolling direction of 870 MPa or more.

11. The copper alloy sheet according to claim 1, having a tensile strength in a direction parallel to the rolling direction of 930 MPa or more.

12. The copper alloy sheet according to claim 1, having an electrical conductivity of 35.0% IACS or more.

13. The copper alloy sheet according to claim 1, having an electrical conductivity of 40.2% IACS or more.

14. An electronic component comprising the copper alloy sheet according to any one of claims 1 to 13.

15. A method for producing a copper alloy sheet, comprising the steps of: hot rolling an ingot of a copper alloy containing 1.50 to 4.60 mass% Ni, 0.10 to 0.80 mass% Co, 0.10 to 1.30 mass% Si, with the balance being Cu and unavoidable impurities; solution treating the obtained copper alloy intermediate; aging treating the copper alloy intermediate; finish cold rolling the copper alloy intermediate; and stress relief annealing the copper alloy intermediate, in this order; and producing the copper alloy intermediate such that the tensile strength A (MPa), 0.2% proof stress B (MPa), and electrical conductivity C (% IACS) of the copper alloy intermediate after the solution treating step and before the aging treating step satisfy the following relationship (1): X = (A × B) / C ... (1) is 582 or more.

16. The method for producing a copper alloy sheet according to claim 15, further comprising a step of annealing the copper alloy sheet after the stress relief annealing step at 300° C. or higher for 1 second or more.

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