Composite copper foil and method for producing the same

Abstract

The present application relates to a kind of composite copper foil and its preparation method.The composite copper foil includes substrate and the first film structure of plating on the front of substrate and the second film structure of plating on the back of substrate;The first film structure and the second film structure each independently include alloy copper layer and pure copper layer of alternative lamination.Compared with the first film structure and the second film structure of plating of pure copper layer in traditional composite copper foil, the composite copper foil of the present application has higher strength and hardness, is not easy to wrinkle deformation, is more conducive to use in subsequent processing process.

Description

Technical Field

[0001] This invention relates to the field of new energy technology, and in particular to a composite copper foil and its preparation method. Background Technology

[0002] Copper foil is a key basic material for the negative electrode of lithium batteries. In lithium-ion batteries, it serves as both a carrier of the negative electrode active material and a collector and conductor of negative electrode electrons. As composite copper foil gradually replaces traditional copper foil in the widespread application of lithium batteries, the quality requirements for the products are becoming increasingly stringent, and the manufacturing process is a crucial factor determining the quality of copper foil products. Currently, the manufacturing process of composite copper foil is relatively complex, often employing sputtering deposition as a base layer followed by electroplating to thicken the foil to achieve the required thickness. The electroplating process is an oxidation-reduction process, utilizing the electrolytic action of current and chemical solutions to deposit metallic copper onto the surface of the electroplated part, forming a metallic copper coating. Because pure copper composite foil has relatively low strength and hardness, it exhibits high plastic deformation capacity after being made into composite copper foil, making it prone to wrinkling and deformation during subsequent processing, affecting the yield and efficiency of the manufacturing process. Summary of the Invention

[0003] Therefore, it is necessary to provide a composite copper foil that can improve strength and hardness, and a method for preparing the same.

[0004] One embodiment of this application provides a composite copper foil, including a substrate, a first coating structure located on the front side of the substrate, and a second coating structure located on the back side of the substrate;

[0005] The first coating structure and the second coating structure each independently include alternating layers of alloy copper and pure copper.

[0006] In one embodiment, the composite copper foil also satisfies at least one of the following conditions:

[0007] (1) In the first coating structure, the number of alloy copper layers is at least one, the number of pure copper layers is at least one, and the layer farthest from the substrate is the alloy copper layer;

[0008] (2) In the second coating structure, the number of alloy copper layers is at least one, the number of pure copper layers is at least one, and the layer farthest from the substrate is the alloy copper layer.

[0009] In one embodiment, the composite copper foil also satisfies at least one of the following conditions:

[0010] (1) The total thickness of the first coating structure is 1μm to 2μm;

[0011] (2) The total thickness of the second coating structure is 1μm to 2μm.

[0012] In one embodiment, the first coating structure further satisfies at least one of the following conditions:

[0013] (1) The thickness of each alloy copper layer is 40nm to 110nm;

[0014] (2) The thickness of each pure copper layer is 180nm to 320nm.

[0015] (3) The total number of layers formed by the alloy copper layer and the pure copper layer is 5 to 8.

[0016] In one embodiment, the second coating structure further satisfies at least one of the following conditions:

[0017] (1) The thickness of each alloy copper layer is 40nm to 110nm;

[0018] (2) The thickness of each pure copper layer is 180nm to 320nm;

[0019] (3) The total number of layers formed by the alloy copper layer and the pure copper layer is 5 to 8.

[0020] In one embodiment, the alloy material of the alloy copper layer comprises copper and other metals in a mass ratio of (4-6):(4-6).

[0021] In one embodiment, a first adhesion layer is further provided between the substrate and the first coating structure, and / or

[0022] A second adhesion layer is further provided between the substrate and the second coating structure;

[0023] Optionally, the materials of the first and second adhesion layers are each independently selected from partially oxidized metals.

[0024] In one embodiment, the substrate material includes one or more of PET, PP, and PI.

[0025] An embodiment of this application also provides a method for preparing composite copper foil as described in any of the above embodiments, comprising the following steps:

[0026] A first coating structure is formed on the front side of the substrate;

[0027] A second coating structure is formed on the reverse side of the substrate;

[0028] The first coating structure and the second coating structure each independently include alternating layers of alloy copper and pure copper.

[0029] In one embodiment, the first coating structure and / or the second coating structure are formed by vacuum magnetron sputtering.

[0030] The composite copper foil provided in this application includes a first coating structure on the front side of the substrate and a second coating structure on the back side of the substrate. The first coating structure and the second coating structure each independently include alternating layers of alloy copper and pure copper. Compared with the first coating structure and the second coating structure composed of pure copper layers in traditional composite copper foil, the composite copper foil of this application has higher strength and hardness, is not easy to wrinkle and deform, and has good flexibility, which is more conducive to its use in subsequent processing. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the composite copper foil structure in Examples 1 and 2.

[0032] Figure 2 This is a schematic diagram of the composite copper foil in Example 3.

[0033] Figure 3 This is a schematic diagram of the composite copper foil in Comparative Example 1.

[0034] Explanation of reference numerals in the attached figures:

[0035] 10: Composite copper foil; 110: Substrate; 120: First adhesion layer; 130: First coating structure; 140: Second adhesion layer; 150: Second coating structure; 101: Alloy copper layer; 102: Pure copper layer. Detailed Implementation

[0036] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0037] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0039] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0040] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0042] One embodiment of this application provides a composite copper foil, including a substrate, a first coating structure located on the front side of the substrate, and a second coating structure located on the back side of the substrate;

[0043] The first and second coating structures each independently comprise alternating layers of alloy copper and pure copper.

[0044] The composite copper foil provided in this application includes a first coating structure on the front side of the substrate and a second coating structure on the back side of the substrate. The first coating structure and the second coating structure each independently include alternating layers of alloy copper and pure copper. Compared with the first coating structure and the second coating structure composed of pure copper in traditional composite copper foil, this application combines the advantages of the good flexibility of pure copper and the good strength and hardness of alloy copper. The resulting composite copper foil not only meets the performance requirements of the process in terms of flexibility and plasticity, but also has higher strength and hardness, is not easy to wrinkle and deform, and is more conducive to use in subsequent processing.

[0045] In one embodiment, in the first coating structure, the number of alloy copper layers is at least one, the number of pure copper layers is at least one, and the layer farthest from the substrate is the alloy copper layer. Compared to pure copper layers, alloy copper layers are less prone to oxidation. Therefore, setting the layer farthest from the substrate as an alloy copper layer in the first coating structure effectively prevents oxidation. Understandably, in the first coating structure, the number of alloy copper layers can be, for example, but not limited to, one, two, three, four, or even more, and the number of pure copper layers can be, for example, but not limited to, one, two, three, four, or even more. They are arranged alternately according to their distance from the substrate, from closest to farthest. The arrangement can be either alloy copper layers first, then pure copper layers, or pure copper layers first, then alloy copper layers. No particular limitation is made in this application, as long as the outermost layer is an alloy copper layer.

[0046] In one embodiment, in the second coating structure, the number of alloy copper layers is at least one, the number of pure copper layers is at least one, and the layer farthest from the substrate is the alloy copper layer. Similarly, in the second coating structure, setting the layer farthest from the substrate as an alloy copper layer is also beneficial for oxidation prevention. Understandably, in the second coating structure, the number of alloy copper layers can be, for example, but not limited to, one, two, three, four, or even more, and the number of pure copper layers can be, for example, but not limited to, one, two, three, four, or even more, arranged alternately from near to far from the substrate. The order of alloy copper layers followed by pure copper layers can be adopted, or the order of pure copper layers followed by alloy copper layers can be adopted. No particular limitation is made in this application, as long as the outermost layer is an alloy copper layer.

[0047] In one embodiment, the total thickness of the first coating structure is 1 μm to 2 μm, and the total thickness of the second coating structure is 1 μm to 2 μm. The total thickness of both the first and second coating structures, each between 1 μm and 2 μm, ensures that the resulting composite copper foil meets the conventional thickness requirements for its application scenarios, making it particularly suitable for lithium battery manufacturing processes. Understandably, the total thickness of the first and second coating structures can, for example, but not limited to, be independently 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, etc.

[0048] In one embodiment, the thickness of each alloy copper layer in the first coating structure is 40 nm to 110 nm. It is understood that the thickness of each alloy copper layer in the first coating structure may be, for example, but not limited to, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, etc.

[0049] In one embodiment, the thickness of each pure copper layer in the first coating structure is 180 nm to 320 nm. It is understood that the thickness of each pure copper layer in the first coating structure can be, for example, but not limited to, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, 310 nm, 320 nm, etc.

[0050] In one embodiment, the total number of layers consisting of the alloy copper layer and the pure copper layer in the first coating structure is 5 to 8. It is understood that the total number of layers consisting of the alloy copper layer and the pure copper layer in the first coating structure can be, for example, but not limited to, 5, 6, 7, 8, etc. Preferably, the total number of layers consisting of the alloy copper layer and the pure copper layer in the first coating structure is 6.

[0051] In one embodiment, in the first coating structure, the thickness of each alloy copper layer is 40nm to 110nm, the thickness of each pure copper layer is 180nm to 320nm, and the total number of layers consisting of alloy copper layers and pure copper layers is 5 to 8. Pure copper has lower hardness but better flexibility, while alloy copper has higher hardness but poorer flexibility. By controlling the thickness of each alloy copper layer and each pure copper layer, and controlling the total number of layers, and using an alternating layering method of pure copper layers and alloy copper layers, the requirements of subsequent processes such as lithium battery manufacturing for the flexibility and plasticity of the composite copper foil material can be met, while effectively improving the hardness and strength of the composite copper foil and reducing wrinkling and deformation during subsequent use.

[0052] In one embodiment, the thickness of each alloy copper layer in the second coating structure is 40 nm to 110 nm. It is understood that the thickness of each alloy copper layer in the second coating structure can be, for example, but not limited to, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, etc.

[0053] In one embodiment, in the second coating structure, the thickness of each pure copper layer is 180nm to 320nm. It is understood that in the second coating structure, the thickness of each pure copper layer can be, for example, but not limited to, 180nm, 190nm, 200nm, 210nm, 220nm, 230nm, 240nm, 250nm, 260nm, 270nm, 280nm, 290nm, 300nm, 310nm, 320nm, etc.

[0054] In one embodiment, the total number of layers consisting of the alloy copper layer and the pure copper layer in the second coating structure is 5 to 8. It is understood that the total number of layers consisting of the alloy copper layer and the pure copper layer in the second coating structure can be, for example, but not limited to, 5, 6, 7, 8, etc. Preferably, the total number of layers consisting of the alloy copper layer and the pure copper layer in the second coating structure is 6.

[0055] Based on similar reasons, it is understood that in one embodiment, in the second coating structure, the thickness of each alloy copper layer is 40nm to 110nm, the thickness of each pure copper layer is 180nm to 320nm, and the total number of layers composed of alloy copper layers and pure copper layers is 5 to 8. It is understood that in the first and second coating structures, the thickness of each alloy copper layer can be the same or different, and the thickness of each pure copper layer can be the same or different; this application does not impose any particular limitation.

[0056] In one embodiment, the alloy material of the copper alloy layer comprises copper and other metals in a mass ratio of (4-6):(4-6). The copper alloy material composed of copper and other metals in the above-mentioned mass ratio possesses suitable strength and flexibility. The resulting copper alloy layer and pure copper layer are alternately layered, resulting in a composite copper foil that simultaneously possesses good flexibility and strength. Understandably, the mass ratio of copper to other metals in the copper alloy can be, for example, but not limited to, 4:6, 5:5, 6:4, etc., and preferably, the mass ratio of copper to other metals in the copper alloy is 6:4. Further, other metals can be, for example, but not limited to, zinc, silver, chromium, tin, etc.

[0057] In one embodiment, a first adhesion layer is further disposed between the substrate and the first coating structure. In another embodiment, a second adhesion layer is further disposed between the substrate and the second coating structure. The first and second adhesion layers help to improve the adhesion between the first and second coating structures and the substrate.

[0058] Furthermore, the materials of the first and second adhesion layers are each independently selected from partially oxidized metals. Partially oxidized metals refer to metal semi-oxides; for example, in magnetron sputtering, using a metal as the target and introducing a certain amount of oxygen during sputtering, partially oxidized metals can be formed after deposition. The aforementioned metals can be, but are not limited to, titanium, niobium, silver, molybdenum, zinc, etc.

[0059] Furthermore, the thickness of the first adhesion layer can be, for example, 15 μm to 25 μm. Preferably, the thickness of the first adhesion layer is 20 μm.

[0060] Furthermore, the thickness of the second adhesion layer can be, for example, 15 μm to 25 μm. Preferably, the thickness of the second adhesion layer is 20 μm.

[0061] In one embodiment, the substrate is made of a polymer material, such as one or more of PET, PP, and PI. Further, the thickness of the substrate is 4 μm to 5 μm, preferably 4.5 μm.

[0062] An embodiment of this application also provides a method for preparing composite copper foil as described in any of the above embodiments, comprising the following steps:

[0063] A first coating structure is formed on the front side of the substrate, and a second coating structure is formed on the back side of the substrate; the first coating structure and the second coating structure each independently include alternating layers of alloy copper and pure copper.

[0064] In one embodiment, a first and / or second coating structure is formed by vacuum magnetron sputtering. Vacuum magnetron sputtering coating refers to filling a vacuum with a reactive inert gas (e.g., argon) to induce a glow discharge. The glow discharge generates charged ions, which are accelerated by an electric field and collide with argon atoms under vacuum conditions, ionizing them to produce argon ions and new ions. These ions are then accelerated by the electric field and the magnetic field behind the target material, bombarding the target surface and ejecting target atoms. Simultaneously, secondary ions are generated, which collide with argon ions again, forming even more ions. The target atoms, carrying sufficient kinetic energy, fly to the substrate surface to deposit and form a film. Vacuum magnetron sputtering coating forms the first and / or second coating structures. This method is relatively simple to operate and allows for easier control of the thickness of each layer. By using multiple pairs of targets for magnetron sputtering coating, composite copper foils with both good toughness and improved strength can be obtained through alternating layers of alloy copper and pure copper without affecting the conductivity of the composite copper foil. Understandably, the first and / or second coating structures can also be formed by other methods such as electroplating. In comparison, the vacuum magnetron sputtering process is easier to control.

[0065] Furthermore, the vacuum magnetron sputtering target has multiple pairs, and the target includes at least an alloy copper target and a pure copper target.

[0066] Understandably, in this application, the process conditions of magnetron sputtering can be adaptively adjusted according to the parameter requirements of the composite copper foil. For example, in one embodiment, the process conditions of vacuum magnetron sputtering for forming the first coating structure and / or the second coating structure include at least: using a DC power supply with a current of 20A to 35A, a voltage of 425V to 470V, and a power supply quantity of 1 to 2 units.

[0067] The following are specific examples.

[0068] Example 1

[0069] Composite copper foil 10 was prepared by magnetron sputtering deposition. The structure of composite copper foil 10 is as follows: Figure 1 As shown, the substrate 110 uses a PET film with a thickness of 4.5 μm, and the target materials include alloy copper target (copper to nickel mass ratio of 6:4), pure copper target, and metallic titanium target. Specific steps include:

[0070] (1) A first adhesion layer 120 with a thickness of 20 nm is formed on the front side of the substrate 110 by magnetron sputtering. The material of the first adhesion layer 120 is a partially oxidized titanium metal layer. The magnetron sputtering conditions include: the sputtering target is titanium metal, oxygen is introduced at 5 sccm; a medium frequency power supply is used, with a current of 20A and a voltage of 500V, and one power supply is used.

[0071] A first coating structure 130 with a total thickness of 1100 nm is formed on the first adhesion layer 120 through the following steps (2) to (8):

[0072] (2) An alloy copper layer 101 with a thickness of 50 nm is formed on the first adhesion layer 120 formed in step (1) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 20A, voltage of 425V, number of power supplies: 1.

[0073] (3) A pure copper layer 102 with a thickness of 200 nm is formed on the alloy copper layer 101 formed in step (2) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 35A, voltage of 470V, number of power supplies: 2.

[0074] (4) An alloy copper layer 101 with a thickness of 100 nm is formed on the pure copper layer 102 formed in step (3) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 35A, voltage of 470V, number of power supplies: 1.

[0075] (5) A pure copper layer 102 with a thickness of 300 nm is formed on the alloy copper layer 101 formed in step (4) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 35A, voltage of 470V, number of power supplies: 2.

[0076] (6) An alloy copper layer 101 with a thickness of 100 nm is formed on the pure copper layer 102 formed in step (5) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 35A, voltage of 470V, number of power supplies: 1.

[0077] (7) A pure copper layer 102 with a thickness of 300 nm is formed on the alloy copper layer 101 formed in step (6) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 35A, voltage of 470V, number of power supplies: 2.

[0078] (8) An alloy copper layer 101 with a thickness of 50 nm is formed on the pure copper layer 102 formed in step (7) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 20A, voltage of 425V, number of power supplies: 1.

[0079] (9) Referring to step (1), a second adhesion layer 140 with a thickness of 20 nm is formed on the reverse side of the substrate 110. The material of the second adhesion layer 140 is partially titanium oxide. Referring to steps (2) to (8), a second coating structure 150 with a total thickness of 1100 nm is formed on the second adhesion layer 140.

[0080] Example 2

[0081] Composite copper foil 10 was prepared by magnetron sputtering deposition. The structure of composite copper foil 10 is as follows: Figure 1 As shown, the substrate 110 uses a PET film with a thickness of 4.5 μm, and the target materials include alloy copper target (copper to nickel mass ratio of 6:4), pure copper target, and metallic titanium. Specific steps include:

[0082] (1) A first adhesion layer 120 with a thickness of 20 nm is formed on the front side of the substrate 110 by magnetron sputtering. The material of the first adhesion layer 120 is a partially oxidized titanium metal layer. The magnetron sputtering conditions include: the sputtering target is titanium metal, oxygen is introduced at 5 sccm; a medium frequency power supply is used, with a current of 20A and a voltage of 500V, and one power supply is used.

[0083] A first coating structure 130 with a total thickness of 1100 nm is formed on the first adhesion layer 120 through the following steps (2) to (8):

[0084] (2) An alloy copper layer 101 with a thickness of 50 nm is formed on the first adhesion layer 120 formed in step (1) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 20A, voltage of 425V, number of power supplies: 1.

[0085] (3) A pure copper layer 102 with a thickness of 200 nm is formed on the alloy copper layer 101 formed in step (2) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 35A, voltage of 470V, number of power supplies: 2.

[0086] (4) An alloy copper layer 101 with a thickness of 50 nm is formed on the pure copper layer 102 formed in step (3) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 35A, voltage of 470V, number of power supplies: 1.

[0087] (5) A pure copper layer 102 with a thickness of 350 nm is formed on the alloy copper layer 101 formed in step (4) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 35A, voltage of 470V, number of power supplies: 2.

[0088] (6) An alloy copper layer 101 with a thickness of 50 nm is formed on the pure copper layer 102 formed in step (5) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 35A, voltage of 470V, number of power supplies: 1.

[0089] (7) A pure copper layer 102 with a thickness of 350 nm is formed on the alloy copper layer 101 formed in step (6) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 35A, voltage of 470V, number of power supplies: 2.

[0090] (8) An alloy copper layer 101 with a thickness of 50 nm is formed on the pure copper layer 102 formed in step (7) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 20A, voltage of 425V, number of power supplies: 1.

[0091] (9) Referring to step (1), a second adhesion layer 140 with a thickness of 20 nm is formed on the reverse side of the substrate 110. The material of the second adhesion layer 140 is partially titanium oxide. Referring to steps (2) to (8), a second coating structure 150 with a total thickness of 1100 nm is formed on the second adhesion layer 140.

[0092] Example 3

[0093] Composite copper foil 10 was prepared by magnetron sputtering deposition. The structure of composite copper foil 10 is as follows: Figure 2 As shown, the substrate 110 uses a PET film with a thickness of 4.5 μm, and the target materials include alloy copper target (copper to nickel mass ratio of 6:4), pure copper target, and metallic titanium. Specific steps include:

[0094] (1) A first adhesion layer 120 with a thickness of 20 nm is formed on the front side of the substrate 110 by magnetron sputtering. The material of the first adhesion layer 120 is a partially oxidized titanium metal layer. The magnetron sputtering conditions include: the sputtering target is titanium metal, oxygen is introduced at 5 sccm; a medium frequency power supply is used, with a current of 20A and a voltage of 500V, and one power supply is used.

[0095] A first coating structure 130 with a total thickness of 1100 nm is formed on the first adhesion layer 120 through the following steps (2) to (4):

[0096] (2) An alloy copper layer 101 with a thickness of 50 nm is formed on the first adhesion layer 120 formed in step (1) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 20A, voltage of 425V, number of power supplies: 1.

[0097] (3) A pure copper layer 102 with a thickness of 1000 nm is formed on the alloy copper layer 101 formed in step (2) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 35A, voltage of 470V, number of power supplies: 2.

[0098] (4) An alloy copper layer 101 with a thickness of 50 nm is formed on the pure copper layer 102 formed in step (3) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 20A, voltage of 425V, number of power supplies: 1.

[0099] (5) Referring to step (1), a second adhesion layer 140 with a thickness of 20 nm is formed on the reverse side of the substrate 110. The material of the second adhesion layer 140 is partially titanium oxide. Referring to steps (2) to (4), a second coating structure 150 with a total thickness of 1100 nm is formed on the second adhesion layer 140.

[0100] Comparative Example 1

[0101] Composite copper foil 10 was prepared by magnetron sputtering deposition. The structure of composite copper foil 10 is as follows: Figure 3 As shown, the substrate 110 uses a PET film with a thickness of 4.5 μm, and the target materials include alloy copper target (copper to nickel mass ratio of 6:4), pure copper target, and metallic titanium. Specific steps include:

[0102] (1) A first adhesion layer 120 with a thickness of 20 nm is formed on the front side of the substrate 110 by magnetron sputtering. The material of the first adhesion layer 120 is a partially oxidized titanium metal layer. The magnetron sputtering conditions include: the sputtering target is titanium metal, oxygen is introduced at 5 sccm; a medium frequency power supply is used, with a current of 20A and a voltage of 500V, and one power supply is used.

[0103] A first coating structure 130 with a total thickness of 1100 nm is formed on the first adhesion layer 120 by the following step (2):

[0104] (2) A pure copper layer 102 with a thickness of 1100 nm is formed on the first adhesion layer 120 formed in step (1) by magnetron sputtering. Magnetron sputtering conditions: DC power supply, current of 35A, voltage of 470V, number of power supplies 2.

[0105] (3) Referring to step (1), a second adhesion layer 140 with a thickness of 20 nm is formed on the reverse side of the substrate 110. The material of the second adhesion layer 140 is partially titanium oxide. Referring to step (2), a second coating structure 150 with a total thickness of 1100 nm is formed on the second adhesion layer 140.

[0106] The composite copper foils prepared in Examples 1 to 3 and Comparative Example 1 were subjected to sheet resistance, tensile strength and puncture strength tests. The test results are shown in Table 1 below.

[0107] The tensile strength test method is as follows: a composite copper foil with a width of 50 mm and a length of 200 mm is used. Both ends are fixed on a precision pull-out force testing instrument. One end of the instrument is fixed and the other end is stretched outward at a speed of 100 mm / min. At this time, a tensile value will be generated. When the composite copper foil is stretched and broken, there will be a tensile peak value, which is the peak tensile strength.

[0108] The puncture strength test method is as follows: A high-precision pressure tester is used. The composite copper foil is fixed on a 50mm*50mm base. There is a 6mm diameter through hole in the center of the base. A 1.5mm diameter spherical metal probe is used to test the puncture strength. The probe runs at a speed of 50mm / min. When the probe touches the composite copper foil, a pressure value is generated. As the probe continues to run downward, the pressure value will increase. When the composite copper foil is punctured, a peak pressure value is generated, which is the peak puncture strength.

[0109] Table 1 Performance test results of composite copper foil

[0110]

[0111] As shown in Table 1, the first film structure and the second coating structure of Examples 1 to 3 are each composed of alternately stacked alloy copper layers and pure copper layers. Compared with the first film structure and the second coating structure of Comparative Example 1, which are composed of only pure copper layers, the composite copper foils obtained by magnetron sputtering coating in Examples 1 to 3 have higher drawing strength and puncture strength. The composite copper foils have higher strength and hardness and are less prone to wrinkling and deformation in subsequent processing.

[0112] A comparison between Examples 1 to 3 also shows that, for the first or second film layer structure, the smaller the difference between the thickness of the alloy copper layer and the thickness of the pure copper layer, the more beneficial it is to obtain composite copper foil with higher comprehensive performance such as drawing strength and puncture strength.

[0113] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0114] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A composite copper foil, characterized by, The substrate and a first coating structure on the front side of the substrate and a second coating structure on the back side of the substrate are provided. The first coating structure and the second coating structure each independently comprise alternating layers of alloy copper layers and pure copper layers. In the first coating structure, each of the alloy copper layers has a thickness of 40-110 nm, each of the pure copper layers has a thickness of 180-320 nm, the total number of layers of the alloy copper layers and the pure copper layers is 5-8, and the layer farthest from the substrate is the alloy copper layer.

2. The composite copper foil according to claim 1, characterized by, In the second coating structure, the number of layers of the alloy copper layers is at least one, the number of layers of the pure copper layers is at least one, and the layer farthest from the substrate is the alloy copper layer.

3. The composite copper foil according to claim 1, characterized by, The total thickness of the first coating structure is 1-2 μm.

4. The composite copper foil according to claim 1, characterized by, The total thickness of the second coating structure is 1-2 μm.

5. The composite copper foil according to claim 1, wherein The second coating structure further satisfies at least one of the following conditions: (1) each of the alloy copper layers has a thickness of 40-110 nm; (2) each of the pure copper layers has a thickness of 180-320 nm; (3) the total number of layers of the alloy copper layers and the pure copper layers is 5-8.

6. The composite copper foil according to any one of claims 1 to 5, characterized by The alloy material of the alloy copper layer comprises copper and other metals in a mass ratio of 4-6:4-6.

7. The composite copper foil according to any one of claims 1 to 5, characterized by A first adhesion layer is further provided between the substrate and the first coating structure, and / or A second adhesion layer is further provided between the substrate and the second coating structure.

8. The composite copper foil according to claim 7, characterized by The material of the first adhesion layer and the second adhesion layer is each independently selected from partially oxidized metals.

9. The composite copper foil according to any one of claims 1 to 5, characterized by The material of the substrate comprises one or more of PET, PP and PI.

10. A method for producing the composite copper foil according to any one of claims 1 to 9, characterized by, The method comprises the following steps: forming a first coating structure on the front side of the substrate; forming a second coating structure on the back side of the substrate; The first coating structure and the second coating structure each independently comprise alternating layers of alloy copper layers and pure copper layers.

11. The method of producing a composite copper foil according to claim 10, wherein The first coating structure and / or the second coating structure are formed by vacuum magnetron sputtering.

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