Aluminum-copper clad material

Abstract

To provide an aluminum-copper clad material that does not have a nickel layer, properly secures, with an easily practicable simple configuration, bonding strength between layers, and can have desired characteristics (mechanical characteristics, electrical conductivity, thermal conductivity, malleability, moldability, workability, weldability, etc.).SOLUTION: An aluminum-copper clad material includes: an aluminum layer; and a copper layer made of copper containing 98 mass% or more of Cu, wherein the aluminum layer includes a pure aluminum layer made of aluminum containing 99 mass% or more of Al and an aluminum alloy layer made of an aluminum alloy; and the pure aluminum layer is present between the aluminum alloy layer and the copper layer and is diffusion-bonded to the aluminum alloy layer and the copper layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an aluminum-copper clad material, and in particular to an aluminum-copper clad material suitable for use as a material for electrode terminals, bus bars (electrode-to-electrode connection plates), conductive cases, lead wires, and other materials that require weight reduction while maintaining electrical properties. [Background technology]

[0002] Conventionally, an aluminum copper clad material that does not have a nickel layer for suppressing a diffusion reaction due to heating has been known (see Patent Document 1).

[0003] The aluminum-copper clad material disclosed in Patent Document 1 is composed of an aluminum layer and a copper layer. This aluminum-copper clad material is diffusion annealed after pressure welding (clad rolling) of an aluminum plate and a copper plate. This aluminum-copper clad material does not have a nickel layer to suppress the diffusion reaction, so a diffusion layer is formed between the aluminum layer and the copper layer. This diffusion layer is composed of a brittle Al-Cu intermetallic compound consisting of Al diffused from the aluminum layer and Cu diffused from the copper layer. This Al-Cu intermetallic compound is generated by heating in the diffusion annealing performed after pressure welding (clad rolling).

[0004] During diffusion annealing after pressure welding, excessive heating causes excessive diffusion, resulting in excessive growth of brittle intermetallic compounds and an excessively thick diffusion layer. In addition, insufficient heating results in an inadequate diffusion, resulting in an inadequate average thickness of the diffusion layer. Therefore, excessive or insufficient heating during diffusion annealing prevents adequate bonding strength between the aluminum layer and the copper layer due to thermal diffusion. Therefore, in Patent Document 1, the average thickness of the diffusion layer is adjusted to a range of 0.5 μm to 10 μm, and the grain size in the aluminum layer and the copper layer near the diffusion layer, 0.5 μm away from the diffusion layer, is adjusted to be 0.5 times or less the grain size in the central portion. By adjusting the structural structure within each layer in this way, bonding strength between each layer is ensured even in an aluminum-copper clad material without a nickel layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2011 / 155379 Summary of the Invention [Problem to be solved by the invention]

[0006] The inventors have experimentally produced an aluminum-copper clad material without a nickel layer by performing pressure welding (clad rolling) and diffusion annealing under typical conditions using an aluminum alloy and pure copper. However, the aluminum-copper clad material obtained by the experiment did not have the expected bonding strength. One possible cause is incompatibility of the pressure welding (clad rolling) and diffusion annealing conditions. Another possible cause is the concentration of oxides produced by the thermal diffusion of aluminum alloy elements in the diffusion layer.

[0007] Patent Document 1 teaches that the surface oxide film (continuous aluminum oxide film) of the aluminum sheet is broken down and dispersed during pressure welding (clad rolling), forming gaps through which the aluminum alloy and pure copper come into direct contact, resulting in the formation of Al-Cu intermetallic compounds. Taking this into consideration, alloying elements such as Mg and Mn diffused from the aluminum alloy may combine with the remaining oxygen between the layers to form oxides in the gaps, which may then concentrate and prevent the proper formation of Al-Cu intermetallic compounds. For example, concentrated, highly hard magnesium oxide may disperse within the diffusion layer, preventing the proper formation of Al-Cu intermetallic compounds. Alternatively, concentrated, highly brittle manganese oxide may disperse within the diffusion layer, weakening its structural structure. Therefore, when using an aluminum alloy, in addition to optimizing the conditions for pressure welding (clad rolling) and diffusion annealing, it is necessary to identify appropriate structural requirements for obtaining sufficient interlayer bonding strength.

[0008] One object of the present invention is to provide an aluminum-copper clad material that does not have a nickel layer, and that has a simple and easily practical structure that ensures appropriate bonding strength between layers and has desired properties (mechanical properties, electrical conductivity, thermal conductivity, ductility, formability, workability, weldability, etc.). [Means for solving the problem]

[0009] The aluminum copper clad material according to the present invention includes an aluminum layer and a copper layer made of copper containing 98% or more by mass of Cu, wherein the aluminum layer is composed of a pure aluminum layer made of aluminum containing 99% or more by mass of Al, and an aluminum alloy layer made of an aluminum alloy, and the pure aluminum layer is located between the aluminum alloy layer and the copper layer and is diffusion bonded to the aluminum alloy layer and the copper layer.

[0010] In the aluminum copper clad material according to the present invention, the pure aluminum layer preferably has an average thickness of 10 μm or more.

[0011] The aluminum copper clad material according to the present invention preferably satisfies t1a / t1b≦10, where t1a is the average thickness of the pure aluminum layer and t1b is the average thickness of the aluminum alloy layer. [Effects of the Invention]

[0012] According to this invention, it is possible to provide an aluminum copper clad material that has a simple and easily practical structure, has appropriate bonding strength between layers, and has desired properties (mechanical properties, electrical conductivity, thermal conductivity, ductility, formability, workability, weldability, etc.). [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing an example of the structure of an aluminum copper clad material according to the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] The aluminum copper clad material according to the present invention will be described below by giving examples of configurations that are considered to be preferred embodiments, with reference to the drawings as needed.

[0015] 1 shows an example of the configuration of an aluminum copper clad material 10 (hereinafter referred to as "clad material 10") according to the present invention. Clad material 10 is particularly suitable as a material for electrode terminals that require lightweight construction while maintaining electrical properties, such as bus bars (interelectrode connection plates), conductive cases, and lead wires.

[0016] As shown in FIG. 1, the clad material 10 (average thickness t) includes an aluminum layer 11 (average thickness t1) and a copper layer 12 (average thickness t2). The aluminum layer 11 is composed of a pure aluminum layer 11a (average thickness t1a) and an aluminum alloy layer 11b (average thickness t1b). The pure aluminum layer 11a is located between the aluminum alloy layer 11b and the copper layer 12 and is diffusion-bonded to the aluminum alloy layer 11b and the copper layer 12. A diffusion layer 11c (average thickness t1c) that is much thinner than both the layers 11a and 11b is formed at the joint between the pure aluminum layer 11a and the aluminum alloy layer 11b. Furthermore, a diffusion layer 13 (average thickness t3) that is much thinner than both the layers 11a and 11b is formed at the joint between the pure aluminum layer 11a and the copper layer 12. Therefore, the clad material 10 shown in FIG. 1 is an aluminum-copper clad material having a three-layer structure (excluding diffusion layers 11c and 13) in which an aluminum alloy layer 11b, a pure aluminum layer 11a, and a copper layer 12 are laminated in this order.

[0017] The clad material 10 and aluminum-copper clad materials having a similar layer structure can be manufactured by a manufacturing method including a material preparation process, a pressure-welding process (clad rolling process), and a diffusion annealing process. In the material preparation process, a pure aluminum plate for forming the pure aluminum layer 11a, an aluminum alloy plate for forming the aluminum alloy layer 11b, and a copper plate for forming the copper layer 12 are prepared. In the pressure-welding process (clad rolling process), the aluminum alloy plate, the pure aluminum plate, and the copper plate are rolled in this order while stacked together, and the three plates are pressure-welded. This pressure-welding process results in a three-layer pressure-welded material in which the aluminum alloy plate, the pure aluminum plate, and the copper plate are stacked and pressure-welded in this order. In the diffusion annealing process, the three-layer pressure-welded material is heated to cause a diffusion reaction between Al and Cu between the layers. This diffusion annealing process ensures appropriate diffusion bonding strength between the aluminum alloy layer 11b, the pure aluminum layer 11a, and the copper layer 12.

[0018] Here, the clad material 10 has diffusion layers 11c and 13 formed by a thermal diffusion reaction during diffusion annealing between the aluminum layer 11b, the pure aluminum layer 11a, and the copper layer 12. The average thickness of these diffusion layers 11c and 13 is extremely small compared to the other three layers. For example, the average thickness of the diffusion layer between the pure aluminum layer and the copper layer is approximately 0.5 μm to 10 μm (see Patent Document 1).

[0019] Regarding the diffusion layer, Patent Document 1 teaches that within the diffusion layer between the pure aluminum layer and the copper layer, an extremely thin, discontinuous oxide film made of aluminum oxide exists along the bonding interface between the diffusion layer and the pure aluminum layer and the bonding interface between the diffusion layer and the copper layer. It is believed that this discontinuous oxide film originates from a natural oxide film formed on the surface of the pure aluminum plate that constitutes the pure aluminum layer. Even if the oxide film on the surface of the pure aluminum plate is removed by polishing or the like, it immediately regenerates upon contact with the air. Therefore, a continuous oxide film exists on the surface of the pure aluminum plate immediately before pressure welding (clad rolling).

[0020] During pressure welding (clad rolling), the oxide film on the surface of a pure aluminum sheet is broken up and dispersed, becoming discontinuous, due to the large plastic deformation of the pure aluminum sheet. Immediately after pressure welding (clad rolling), the surface of the pure aluminum sheet (layer) is not exposed to the air, so the broken up and dispersed oxide film remains. During diffusion annealing, fine Al-Cu intermetallic compounds with random crystal orientations are generated near the pressure-welded interface between the pure aluminum layer and the copper layer by a thermal diffusion reaction (see Patent Document 1). Because these fine intermetallic compounds grow with random orientations, the discontinuous oxide film is further broken up and dispersed, forming many gaps in the oxide film. The many gaps in the oxide increase the opportunities for direct contact between the pure aluminum and copper, which facilitates the formation of Al-Cu intermetallic compounds and ensures the proper formation of an intermetallic compound layer (diffusion layer). This is believed to enable the proper diffusion bonding strength to be obtained between the pure aluminum layer and the copper layer.

[0021] <Aluminum layer> In the clad material 10 shown in FIG. 1 , the aluminum layer 11 is composed of a pure aluminum layer 11a and an aluminum alloy layer 11b. The aluminum layer 11 composed of the pure aluminum layer 11a and the aluminum alloy layer 11b has a simple structure in which the pure aluminum layer 11a and the aluminum alloy layer 11b are made of a homogeneous Al-based metallic material, making it easily practical. Because the pure aluminum layer 11a and the aluminum alloy layer 11b are made of a homogeneous Al-based metallic material, a homogeneous diffusion layer 11c is formed between the pure aluminum layer 11a and the aluminum alloy layer 11b by a thermal diffusion reaction (self-diffusion) of Al. This homogeneous diffusion layer 11c ensures adequate bonding strength between the pure aluminum layer 11a and the aluminum alloy layer 11b. Furthermore, if the pure aluminum layer 11a is substantially free of alloying elements or impurity elements, a thermal diffusion reaction between Al and Cu occurs appropriately between the pure aluminum layer 11a and the copper layer 12. Therefore, an intermetallic compound layer (diffusion layer 13) made of an Al-Cu based intermetallic compound is properly formed between the pure aluminum layer 11a and the copper layer 12. Therefore, by employing the aluminum layer 11 made up of the pure aluminum layer 11a and the aluminum alloy layer 11b, it is possible to properly form the clad material 10 (aluminum copper clad material) that does not have a nickel layer.

[0022] Furthermore, by configuring the aluminum layer 11 with the pure aluminum layer 11a and the aluminum alloy layer 11b, the properties of the pure aluminum layer 11a (electrical conductivity, thermal conductivity, formability, workability, weldability, etc.) can be efficiently utilized. At the same time, the properties of the aluminum alloy layer 11b (mechanical properties such as tensile strength, yield strength, and hardness, ductility, formability, workability, weldability, etc.) can be efficiently utilized. Furthermore, compared to a layer structure consisting of a nickel layer and a pure aluminum layer or a layer structure consisting of a nickel layer and an aluminum alloy layer, the difference between the nickel and aluminum-based materials results in a reduced specific electrical resistance of the clad material (improved electrical conductivity), an increased thermal conductivity (improved thermal conductivity), and improved formability and workability.

[0023] <Pure aluminum layer> In the clad material 10 shown in FIG. 1 , the pure aluminum layer 11a is made of aluminum containing 99% or more by mass of Al. Aluminum containing 99% or more by mass is classified as a non-heat-treatable aluminum alloy, such as the JIS A1000 series, but is generally classified as pure aluminum. Pure aluminum has better malleability than pure nickel and is suitable for rolling and press processing, which plastically deforms the aluminum using compressive force. Therefore, pure aluminum sheets can be easily pressure-bonded to both copper sheets and aluminum alloy sheets by clad rolling. Furthermore, pure aluminum has a lower hardness and work-hardening coefficient (n value) than aluminum alloys and pure copper. Therefore, the degree of work-hardening during pressure welding (clad rolling) is relatively small, allowing the pure aluminum sheet to be smoothly spread between the aluminum alloy sheet and the copper sheet. As a result, the pure aluminum layer 11a can be easily pressure-bonded to both the aluminum alloy layer 11b and the copper layer 12.

[0024] The pure aluminum suitable for the pure aluminum layer 11a is preferably the JIS A1000 series or a series having a composition similar thereto, taking into consideration mechanical properties such as tensile strength, yield strength, elongation, and hardness, electrical conductivity, thermal conductivity, ductility, formability, workability, and weldability. For example, A1050, A1070, A1080, A1085, A1100, and A1200 may be used, which have good electrical conductivity, thermal conductivity, formability, workability, and weldability.

[0025] <Aluminum alloy layer> In the clad material 10 shown in FIG. 1, the aluminum alloy layer 11b is made of an aluminum alloy. Compared to pure aluminum, aluminum alloys have excellent mechanical properties, particularly tensile strength, yield strength, and hardness. These unique properties of aluminum alloys can be utilized by forming the aluminum alloy layer 11b from an aluminum alloy. Furthermore, by forming the clad material 10 so that the aluminum alloy layer 11b using an aluminum alloy with desired properties is dominant, it is possible to impart the desired properties attributable to the aluminum alloy to the clad material 10. For example, by using aluminum alloys such as A3003 and A5052, which will be described later, it is possible to form the clad material 10 including the aluminum alloy layer 11b, which has excellent mechanical properties, ductility, formability, workability, and weldability.

[0026] The aluminum alloy suitable for the aluminum alloy layer 11b is preferably a non-heat-treatable aluminum alloy, from the viewpoint of obtaining pressure bonding strength by pressure welding and diffusion bonding strength by diffusion annealing between the layers of the clad material 10. Non-heat-treatable aluminum alloys are alloys that obtain a predetermined strength mainly through cold working, such as rolling, such as the JIS A3000 series, A4000 series, and A5000 series. On the other hand, heat-treatable aluminum alloys are alloys that obtain a predetermined strength through heat treatment, such as quenching and tempering, such as the JIS A2000 series, A6000 series, and A7000 series. Note that the JIS A1000 series, which belongs to the non-heat-treatable aluminum alloys, and those having compositions similar thereto, are treated as pure aluminum in this invention.

[0027] Suitable non-heat-treatable aluminum alloys for the aluminum alloy layer 11b are those with compositions similar to those specified by the JIS A3000 and A5000 series, taking into consideration mechanical properties such as tensile strength, yield strength, elongation, and hardness, as well as electrical conductivity, thermal conductivity, ductility, formability, workability, and weldability. Examples include A3003, A3103, A3203, A5005, A5052, A5154, and A5454, which offer excellent mechanical properties, ductility, formability, workability, and weldability. Other suitable alloys include A3004, A3104, A3105, A5021, A5042, A5082, and A5182, which offer excellent mechanical properties, ductility, formability, and workability. Other suitable alloys include A5083 and A5086, which offer excellent mechanical properties and weldability.

[0028] <Copper layer> In the clad material 10 shown in FIG. 1 , the copper layer 12 is made of copper containing 98% or more by mass of Cu. Copper containing 98% or more by mass of Cu is generally classified as pure copper. Pure copper contains 98% or more by mass of Cu, which has low specific electrical resistivity and high thermal conductivity, and therefore has excellent electrical and thermal conductivity. These unique properties of pure copper can be utilized by constructing the copper layer 12 from pure copper. Furthermore, by constructing the clad material 10 so that the copper layer 12 using pure copper with desired properties is dominant, it is possible to impart the desired properties attributable to pure copper to the clad material 10. For example, by using C1020 or C1100, described below, it is possible to construct a clad material 10 including a copper layer 12 with excellent mechanical properties, electrical conductivity, thermal conductivity, ductility, formability, workability, and weldability.

[0029] The pure copper suitable for the copper layer 12 is preferably C1000 series copper as specified by JIS or copper with a composition similar thereto, taking into consideration mechanical properties such as tensile strength, yield strength, elongation, and hardness, as well as properties such as electrical conductivity, thermal conductivity, ductility, formability, workability, and weldability. Examples of suitable pure copper include C1020, C1100, C1201, C1220, C1441, C1510, C1921, and C1940.

[0030] <Average thickness of pure aluminum layer> In the clad material 10 shown in FIG. 1, when the aluminum layer 11 is made up of the pure aluminum layer 11a and the aluminum alloy layer 11b, the average thickness of the pure aluminum layer 11a is preferably 10 μm or more.

[0031] When an aluminum alloy is used in an aluminum-copper clad material, there is a motivation to effectively utilize the properties unique to that aluminum alloy. For example, if the average thickness of the pure aluminum layer 11a is configured to be excessively large relative to the average thickness of the aluminum alloy layer 11b, pure aluminum will become dominant in the aluminum layer 11, and properties unique to aluminum alloys, such as tensile strength and yield strength, will not be effectively exhibited. When pure aluminum becomes dominant, the properties attributable to the aluminum alloy will not reach their expected values. Therefore, the average thickness of the pure aluminum layer 11a is preferably set taking into consideration the proportion of aluminum alloy in the aluminum layer 11 and the properties to be utilized.

[0032] In the clad material 10, if the softer pure aluminum layer 11a is excessively thick, the harder aluminum alloy layer 11b and the copper layer 12 become relatively thin. If the harder aluminum alloy layer 11b and the copper layer 12 are excessively thin compared to the soft pure aluminum layer 11a, the aluminum alloy layer 11b and the copper layer 12 cannot follow the large plastic deformation of the pure aluminum layer 12a during pressure welding (clad rolling). This causes distortion of the aluminum alloy layer 11b and the copper layer 12, resulting in quality defects such as waviness, wrinkles, surface cracks (cracks on the surface of the aluminum alloy layer 11b), longitudinal warpage, and wavy edges. Therefore, when the average thickness of the pure aluminum layer 11a is t1a and the average thickness of the aluminum alloy layer 11b is t1b, the average thickness of the pure aluminum layer 11a is preferably set to satisfy t1a / t1b≦10, taking into consideration the ductility of the aluminum alloy layer 11b and the copper layer 12.

[0033] As the value of "t1a / t1b" increases, pure aluminum, which has better electrical conductivity than aluminum alloys and is softer, becomes dominant within the aluminum layer 11. Therefore, an aluminum-copper clad material with a large value of t1a / t1b is advantageous for applications that prioritize electrical conductivity or applications that prioritize processability and formability. On the other hand, as the value of "t1a / t1b" decreases, aluminum alloys, which have better mechanical strength than pure aluminum, become dominant within the aluminum layer 11. Therefore, an aluminum-copper clad material with a small value of t1a / t1b is advantageous for applications that prioritize mechanical strength.

[0034] When manufacturing an aluminum-copper clad material having a configuration satisfying the above-mentioned "t1a / t1b≦10," pressure welding (clad rolling) of the two materials is fully possible in view of the difference in deformation resistance between a typical pure aluminum sheet and an aluminum alloy sheet used as the base material, and the above-mentioned quality defects such as wrinkles and surface cracks are unlikely to occur. Note that if the average thickness of the aluminum alloy layer is excessively small (e.g., less than 30 μm), there is a risk of insufficient mechanical strength of the aluminum layer 11 and, depending on the application, defects. For example, when an aluminum-copper clad material is used as a battery terminal component, the aluminum alloy may penetrate into the underlying pure aluminum layer during welding with a connecting component such as a bus bar. In this case, the average thickness of the aluminum alloy layer is preferably 100 μm or more. This reduces the risk of instability in the mechanical properties and quality of the weld, spatter scattering, and other problems caused by the aluminum alloy penetrating into the pure aluminum layer during welding. Furthermore, in applications where the aluminum alloy layer ensures the mechanical strength of the aluminum-copper clad material, the average thickness of the aluminum alloy layer is preferably 30 μm or more. Furthermore, when the average thickness of the aluminum alloy layer is set to 30 μm or more, it is expected that the above-mentioned quality defects caused by pressure welding (clad rolling) will be reduced.

[0035] The above "t1a / t1b" refers to the ratio (layer thickness ratio) of the average thickness of the pure aluminum layer 11a to the average thickness of the aluminum alloy layer 11b. This layer thickness ratio can also be expressed in the form of "t1a:t1b." For example, "t1a / t1b=10" and "10:1," "t1a / t1b=1" and "1:1," and "t1a / t1b=0.1" and "1:10" are equivalent.

[0036] Furthermore, when using an aluminum alloy in an aluminum-copper clad material, attention must be paid to the thermal diffusion reaction of the alloying elements contained in the aluminum alloy. Depending on the material, aluminum alloys contain alloying elements such as Mg, Mn, Cu, and Cr with Al. Regarding the thermal diffusion of aluminum alloying elements, it is known that the diffusion coefficient of Cu (impurity diffusion) in the aluminum base material is larger than that of Al (self-diffusion), and that Mg (impurity diffusion) is larger than that of Cu. For example, consider an aluminum-copper clad material using an aluminum alloy, such as the general-purpose A5052, in which one of the alloying elements is Mg. Typical diffusion annealing for pressure-welded materials involves passing the pressure-welded material through a temperature range of approximately 450°C to 530°C for 1 to 3 minutes. In this case, the diffusion distance of Mg diffusing from the aluminum alloy layer 11b through the pressure-welded interface (the bonding interface after pressure-welding and before thermal diffusion) into the pure aluminum layer 11a is thought to be approximately 4 μm to 12 μm (1 minute to 3 minutes) at 450°C, and approximately 11 μm to 32 μm (1 minute to 3 minutes) at 530°C.

[0037] Considering the above-mentioned diffusion distance of Mg, if the average thickness of the pure aluminum layer 11a is excessively small, alloying elements such as Mg diffused from the aluminum alloy layer 11b may pass through the pure aluminum layer 11a and reach the bonded interface with the copper layer 12. If alloying elements such as Mg contained in the aluminum alloy reach the bonded interface with the copper layer 12, they may combine with the remaining oxygen at the bonded interface to form oxides such as magnesium oxide. If such oxides are formed, the bonding strength between the pure aluminum layer 11a and the copper layer 12 will be inadequate, as described above. Therefore, the lower limit of the average thickness of the pure aluminum layer 11a is preferably set to 10 μm or more, as described above, taking into account the type of alloying elements in the aluminum alloy and the diffusion annealing conditions (holding temperature, holding time). However, in this invention, the lower limit of the average thickness of the pure aluminum layer 11a is not limited to 10 μm or more. In the present invention, the lower limit of the average thickness of the pure aluminum layer 11a can be set, for example, to 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, or 40 μm, taking into consideration the proportion of pure aluminum in the aluminum layer 11 and the properties to be utilized.

[0038] As described above, according to the present invention, an aluminum copper clad can be provided which includes an aluminum layer and a copper layer made of copper containing 98% or more by mass of Cu, and the aluminum layer is composed of a pure aluminum layer made of aluminum containing 99% or more by mass of Al, and an aluminum alloy layer made of an aluminum alloy, and the pure aluminum layer is between the aluminum alloy layer and the copper layer and is diffusion bonded to the aluminum alloy layer and the copper layer.This makes it possible to provide an aluminum copper clad which has an appropriate bonding strength between layers with a simple and easily practical configuration and which has desired properties (mechanical properties, electrical conductivity, thermal conductivity, ductility, formability, workability, weldability, etc.).

[0039] Furthermore, by making the average thickness of the pure aluminum layer preferably 10 μm or more, or by making the average thickness of the pure aluminum layer and the average thickness of the aluminum alloy layer preferably satisfy the above-mentioned relationship "t1a / t1b≦10," it is possible to provide a more preferable aluminum-copper clad material that has an appropriate bonding strength between layers with a simple and easily practical configuration and has desired properties (mechanical properties, electrical conductivity, thermal conductivity, ductility, formability, workability, weldability, etc.).

[0040] <Modification> The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0041] For example, in this embodiment, the aluminum copper clad material is suitable as a material for electrode terminals that require lightweight construction while maintaining electrical properties, and applications of the material for bus bars (electrode connection plates), conductive cases, lead wires, etc. have been exemplified, but the present invention is not limited thereto. The aluminum copper clad material according to the present invention may also be used as a heat dissipation member for heat diffusion in electronic circuit boards, resistors, power modules, MCUs (microcontrollers), and other packaged products.

[0042] In this embodiment, Mg is exemplified as an alloying element contained in the aluminum alloy, and magnesium oxide is exemplified as an oxide produced by a heating diffusion reaction during diffusion annealing, but the present invention is not limited thereto. In this invention, examples of alloying elements or impurity elements other than Cu contained in the aluminum alloy include Mg, Mn, Cr, Si, Fe, Zn, Ti, Ga, V, Ni, V, and Zr. [Explanation of symbols]

[0043] 10: Clad material 11: Aluminum layer 11a: Pure aluminum layer 11b: Aluminum alloy layer 11c: Diffusion layer (intermetallic compound layer) 12: Copper layer 13: Diffusion layer (intermetallic compound layer) t: average thickness of aluminum copper clad material t1: average thickness of the aluminum layer t1a: average thickness of the pure aluminum layer t1b: average thickness of the aluminum alloy layer t1c: average thickness of the diffusion layer t2: average thickness of copper layer t3: average thickness of the diffusion layer

Claims

1. an aluminum layer and a copper layer made of copper containing 98 mass % or more of Cu, the aluminum layer is composed of a pure aluminum layer made of aluminum containing 99 mass % or more of Al, and an aluminum alloy layer made of an aluminum alloy, The aluminum copper clad material, wherein the pure aluminum layer is located between the aluminum alloy layer and the copper layer and is pressure-welded to the aluminum alloy layer and the copper layer by diffusion bonding.

2. 2. The aluminum copper clad material according to claim 1, wherein the pure aluminum layer has an average thickness of 10 μm or more.

3. 3. The aluminum copper clad material according to claim 1, wherein t1a is an average thickness of the pure aluminum layer and t1b is an average thickness of the aluminum alloy layer, and t1a / t1b≦10 is satisfied.

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