Metal foil, circuit board, copper-clad laminate, negative electrode material for battery, and battery

Abstract

Disclosed in the present application are a metal foil, a circuit board, a copper-clad laminate, a negative electrode material for a battery, and a battery. The metal foil comprises a first surface and an opposing second surface, where the average grain size of a metal on the first surface is less than the average grain size of a metal on the second surface. With respect to the metal foil, circuit board, copper-clad laminate, negative electrode material for a battery, and battery of the present application, by means of sensible planning the average grain sizes of the metal foil, the metal foil has been made to possess good corrosion resistance and anti-side corrosion properties, over-etching by an etching solution causing a metal circuit to have an upside-down trapezoidal shape can be effectively prevented, the quality of the metal foil is effectively improved, and the electrical properties of a circuit board are guaranteed.

Description

Metal foil, circuit boards, copper-clad laminates, battery negative electrode materials and batteries

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the Patent Office of China on December 25, 2023, with application number 202311794923.4 and invention name “Metal foil, circuit board, copper-clad laminate, negative electrode material for battery and battery”, and the Chinese patent application filed with the Patent Office of China on February 1, 2024, with application number 202410148785.0 and invention name “Metal foil, circuit board, copper-clad laminate, negative electrode material for battery and battery”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of electrolytic copper foil, and in particular to metal foil, circuit boards, copper-clad laminates, negative electrode materials for batteries, and batteries. Background Art

[0004] Metal foil is a vital material widely used in the electronics industry, particularly in copper-clad laminates and printed circuit boards. It plays a crucial role in conducting circuits and interconnecting components within printed circuit boards, and has been called the "neural network" for signal and power transmission and communication in electronic products. It is also a crucial raw material in chip packaging and new energy batteries.

[0005] With the development of electronic information technology, the use of multi-layer, complex, or high-density, fine-circuit PCBs is increasing in high-precision, miniaturized electronic products. High-precision electronic metal foil or double-sided roughened electrolytic metal foil is typically used for the inner layers of high-density, fine-circuit PCBs or multi-layer, complex PCBs. However, it has been found that traditional metal foil is prone to excessive etching when etching circuits, resulting in an inverted trapezoidal shape. This can lead to the following problems: 1) The circuit spacing becomes wider, reducing the contact area between the circuit and the substrate, thereby weakening the bonding strength between the circuit and the substrate. The circuit is easily delaminated from the circuit substrate, resulting in circuit failure or unstable circuit performance, and reducing product yield; 2) The original circuit area is reduced, thereby reducing signal transmission efficiency.

[0006] Summary of the Invention

[0007] The present application provides metal foil, circuit board, copper-clad laminate, battery negative electrode material and battery. By rationally planning the average grain size of the metal, the metal foil has good corrosion resistance and side corrosion resistance, and can effectively prevent the etching solution from over-etching the metal circuit to form an inverted trapezoidal shape, thereby effectively improving the quality of the metal foil and ensuring the electrical performance of the circuit board.

[0008] In order to solve the above technical problems, an embodiment of the present application provides a metal foil, comprising a first surface and a second surface opposite to each other, wherein the average metal grain size of the first surface is smaller than the average metal grain size of the second surface.

[0009] As one of the optional solutions, the range of the average metal grain size a1 of the thickness H1 is 0.05≤a1<0.2μm; the range of the average metal grain size a2 of the thickness H2 is 0.2≤a2<0.3μm; the range of the average metal grain size a3 of the thickness H3 is 0.3≤a3≤2μm;

[0010] The thickness of H1 is from the first surface to 15-25% of the thickness of the entire metal foil; the thickness of H2 is from the first surface to 15-25% of the thickness of the entire metal foil and ends from the second surface to 20-40% of the thickness of the entire metal foil; the thickness of H3 is from the second surface to 20-40% of the thickness of the entire metal foil.

[0011] As one optional solution, the thickness of H1 is 0.01 to 1 μm; or / and, the thickness of H2 is 0.2 to 2 μm; and / or, the thickness of H3 is 0.5 to 3 μm.

[0012] As an optional solution, the second surface is a non-flat surface.

[0013] As an optional solution, the roughness Rz of the non-flat surface is 0.4-3 μm.

[0014] As an optional solution, the overall thickness of the metal foil is 1 to 15 μm.

[0015] As an optional solution, the metal foil includes an anti-oxidation layer, and the anti-oxidation layer is provided on the first surface and / or the second surface.

[0016] As an optional solution, the metal foil includes a peeling layer, and the peeling layer is provided on the first surface.

[0017] As an optional solution, the metal foil includes a carrier layer, and the carrier layer is provided on a side of the release layer away from the first surface.

[0018] As one optional solution, the metal material of the metal foil is any one of nickel, titanium, copper, silver, gold, platinum, iron, cobalt, chromium, tungsten, molybdenum, aluminum, magnesium, potassium, sodium, calcium, strontium, barium, germanium, antimony, lead, indium and zinc; or,

[0019] The metal material is an alloy formed by any two of nickel, titanium, copper, silver, gold, platinum, iron, cobalt, chromium, tungsten, molybdenum, aluminum, magnesium, potassium, sodium, calcium, strontium, barium, germanium, antimony, lead, indium and zinc.

[0020] As an optional solution, the metal foil further includes a dielectric layer, and the dielectric layer is disposed on the surface of at least one of the metal foils.

[0021] As one of the optional options, the material of the dielectric layer is selected from at least one of polyimide, epoxy resin, modified epoxy resin, modified acrylic resin, cyanate resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polyethylene naphthalate, polystyrene, polyvinyl chloride, polysulfone, polyphenylene sulfide, polyetheretherketone, polyphenylene oxide, polytetrafluoroethylene, liquid crystal polymer, polyoxadiazole, epoxy glass cloth, BT resin, metal, and ceramics.

[0022] As an optional solution, the metal foil further includes an adhesive layer, and the adhesive layer is provided on the surface of at least one of the metal foils.

[0023] As one optional solution, the material of the adhesive layer is selected from at least one of polystyrene, vinyl acetate, polyester, polyethylene, polyamide, rubber or acrylic thermoplastic resins, phenolic, epoxy, thermoplastic polyimide, urethane, melamine or alkyd thermosetting resins, BT resin, and ABF resin.

[0024] Another embodiment of the present application provides a copper-clad laminate comprising the metal foil as described above.

[0025] Another embodiment of the present application provides a circuit board, which includes the metal foil as described above or the copper-clad laminate as described above.

[0026] Another embodiment of the present application provides a semiconductor material, which is prepared from the metal foil as described above.

[0027] Yet another embodiment of the present application provides a negative electrode material for a battery, the negative electrode material comprising the metal foil as described above and an electrode active material coated on a surface of the metal foil.

[0028] Yet another embodiment of the present application provides a battery, comprising the negative electrode material as described above.

[0029] Compared with the prior art, the embodiments of the present application have the following advantages:

[0030] (1) In order to prevent the etching solution from over-etching the circuit to form an inverted trapezoidal structure, the present application improves the metal foil for preparing the circuit, adjusts the metal grain size in the metal foil, sets the distribution of metal grains of different average grain sizes at different positions, and sets the average metal grain size of the first surface to be smaller than the average metal grain size of the second surface, thereby controlling the etching speed of the etching solution and preventing the metal foil from being over-etched to form an inverted trapezoidal structure of the circuit. On the one hand, it avoids the separation of the circuit and the substrate and improves the peeling strength between the circuit and the substrate. On the other hand, it ensures the stability of the circuit signal transmission;

[0031] (2) When the average metal grain size a1 from the first surface to 15% to 25% of the overall metal foil thickness (H1) is in the range of 0.05 ≤ a1 < 0.2 μm, the average metal grain size a2 from the first surface to 15% to 25% of the overall metal foil thickness and from the second surface to 20% to 40% of the overall metal foil thickness (H2) is in the range of 0.2 ≤ a2 < 0.3 μm, and the average metal grain size a3 from the second surface to 20% to 40% of the overall metal foil thickness (H3) is in the range of 0.3 ≤ a3 ≤ 2 μm, the metal foil of the present application can have good corrosion resistance and side corrosion resistance;

[0032] (3) When the metal foil provided by the present application is selected, during the etching process, the etching solution will first contact the first surface. Due to the grain size limitation of the first surface, the grains with small size are easily etched. When the solution reaches the middle position of the metal foil, the etching speed of the solution is slowed down due to the larger grain size. Similarly, when the etching solution reaches the second surface, the etching speed of the solution is further slowed down due to the larger grain size. Therefore, side etching of the metal foil during the etching process is avoided, thereby effectively improving the quality of the metal foil and ensuring the electrical performance of the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a schematic diagram of a metal foil in one embodiment of the present application;

[0034] FIG2 is a schematic diagram of a metal foil in one embodiment of the present application;

[0035] FIG3 is a schematic diagram of a metal foil in one embodiment of the present application;

[0036] Reference numerals:

[0037] Among them, 1. metal foil; 11. second surface; 111. metal grains; 2. anti-oxidation layer; 3. peeling layer; 4. carrier layer. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. The purpose of providing these embodiments is to make the disclosure of this application more thorough and comprehensive. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0039] In the description of this application, the terms "first," "second," "third," etc. are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first," "second," "third," etc. may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0040] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the two elements. The terms "vertical", "horizontal", "left", "right", "up", "down" and similar expressions used herein are for illustrative purposes only, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. The term "and / or" used herein includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood by those skilled in the art in specific circumstances.

[0042] Example 1

[0043] Please refer to FIG. 1 , which conceptually shows a schematic structural diagram of a metal foil provided in an embodiment of the present application. The metal foil includes a first surface and a second surface 11 opposite to each other, and metal grains 111 .

[0044] In an embodiment of the present application, in order to prevent the etching solution from over-etching the circuit to make it an inverted trapezoid, resulting in the widening of the circuit spacing, reducing the contact area between the circuit and the substrate, reducing the bonding force between the circuit and the substrate, and easily causing delamination from the circuit substrate, reducing the efficiency of signal transmission, and reducing the yield rate of the product, the present application has made improvements to the metal foil for preparing the circuit. Specifically, the metal grain size in the metal foil is set so that the average metal grain size of the first surface is smaller than the average metal grain size of the second surface, that is, the closer to the first surface, the smaller the average metal grain size, and the closer to the second surface, the larger the average metal grain size.

[0045] After a large number of experiments and analyses, the applicant found that when the average grain size a1 of the metal from the first surface to 15% to 25% of the thickness of the entire metal foil (H1) is in the range of 0.05≤a1<0.2μm, for example, the average grain size a1 of the metal can be 0.05μm, 0.06μm, 0.08μm, 0.09μm, 0.1μm, 0.19μm or a range formed by any of the above values, and the average grain size a1 from the first surface to 1% of the thickness of the entire metal foil is in the range of 0.05≤a1<0.2μm. 5%, 18%, 20%, 22%, 24%, 25% or a numerical range formed by any of the foregoing values; from the first surface to 15-25% of the thickness of the entire metal foil to the second surface to 20-40% of the thickness of the entire metal foil (H2), the average grain size a2 of the metal is in the range of 0.2≤a2<0.3μm, for example, the average grain size a2 can be 0.2μm, 0.25μm, 0.26μm, 0.28μm , 0.29 μm or a numerical range formed by any of the foregoing values; the average grain size a3 of the metal from the second surface to 20-40% of the thickness of the entire metal foil (H3) is in the range of 0.3≤a3≤2 μm, for example, the average grain size a3 can be 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 When the thickness of the metal foil is 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 35%, 38%, 40% or any of the above values, and the thickness of the metal foil is from the second surface to 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 35%, 38%, 40% or any of the above values, the metal foil can have good corrosion resistance and side corrosion resistance, thereby effectively preventing the etching solution from over-etching and causing the metal circuit to become an inverted trapezoid, effectively improving the quality of the metal foil and ensuring the electrical performance of the circuit board.

[0046] It should be noted that the average grain size of the metal foil can be measured by EBSD (electron backscatter diffraction) for average distribution statistics, and the grain size in the thickness direction can be measured by EBSD (electron backscatter diffraction). The grain sizes a1, a2, and a3 described in this application are the average grain sizes obtained by measuring the cross-sectional view of the metal foil. The thickness ranges H1, H2, and H3 are calculated based on the ratio of the total thickness of the metal foil cross-sectional view measured by scanning electron microscopy (SEM); the roughness of the subsequent second surface, which is a non-flat surface, can be measured using a roughness meter. Specifically, when the etching process is carried out, the etching solution will first contact the first surface. Due to the grain size limitation of the first surface, the small grain size is easily etched. When the solution reaches the middle position of the metal foil, the grain size is larger than that of the first surface, which slows down the etching speed of the solution. Similarly, when the etching solution reaches the second surface position, the larger grain size further slows down the etching speed of the solution. Thus, side etching of the metal foil during the etching process is avoided, thereby effectively improving the yield rate of the product.

[0047] It is understood that factors affecting the etching rate of the solution include not only the metal particle size but also the thickness of the metal foil. Furthermore, the overall thickness of the metal foil affects its use in high-precision, small, or lightweight electronic products. Therefore, the thickness distribution of grains of different grain sizes is particularly important. In an optional embodiment, to ensure the effectiveness of the metal foil, the thickness from the first surface to the point (H1) that accounts for 15-25% of the overall metal foil thickness in this embodiment is 0.01-1 μm, for example, 0.01 micron, 0.02 micron, 0.5 micron, 0.7 micron, 1 micron, etc., or a range of values ​​formed between any of the aforementioned values. In this embodiment, the thickness from the first surface to a point where the metal foil accounts for 15-25% of the total thickness, and from the second surface to a point where the metal foil accounts for 20-40% of the total thickness (H2) is 0.2-2 μm, and can be, for example, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.7 μm, 1 μm, 2 μm, or any range of values ​​between the aforementioned values. In this embodiment, the thickness from the second surface to a point where the metal foil accounts for 20-40% of the total thickness (H3) is 0.5-3 μm, and can be, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, or any range of values ​​between the aforementioned values. Through the above configuration, it was found that the combination of grain size and thickness can effectively control the etching rate of the solution, ensuring that the circuit is not over-etched and maintains a good shape.

[0048] For example, in one embodiment, the metal foil of the present application can be obtained by the following method: forming a metal foil having a total thickness of 0.1 to 10 μm on a titanium roller by chemical deposition (e.g., electroplating), wherein the average metal grain size a1 from the first surface to 15% to 25% of the total metal foil thickness (i.e., thickness H1) is in the range of 0.05 ≤ a1 < 0.2 μm; the average metal grain size a2 from the first surface to 15% to 25% of the total metal foil thickness to the second surface to 20% to 40% of the total metal foil thickness (i.e., thickness H2) is in the range of 0.2 ≤ a2 < 0.3 μm; and the average metal grain size a3 from the second surface to 20% to 40% of the total metal foil thickness (i.e., thickness H3) is in the range of 0.3 ≤ a3 ≤ 2 μm. A represents the metal foil product of the embodiment of the present application, and four metal foil samples, A1, A2, A3, and A4, are randomly selected for comparison with comparative example B. Among them, the parameters of each metal sample are as follows:

[0049] Table 1: Parameters of various metal samples

[0050] Note: In this embodiment, the thickness of the metal foil H2 is the thickness from the first surface to the percentage (%) of the overall metal foil thickness to the second surface to the percentage (%) of the overall metal foil thickness in each sample. In this embodiment, the average grain size of the metal is obtained by the following method: take any length on the cross-sectional view of the metal foil, and measure the average grain size (area-weighted mean) within the thickness of H1, H2, and H3 respectively by EBSD or SEM, that is, the average grain size of the metal distributed as a whole in the thickness of H1, H2, and H3. Metal foil samples A and B are prepared into 50cm×60cm circuit board test boards, and the modified semi-additive method (mSAP) is used to produce fine lines with a line width and line spacing of 25μm / 25μm and a line height of 25μm. The shape of the prepared circuit is observed by metallographic sectioning to see if an inverted trapezoidal circuit appears. The test results are shown in the following table:

[0051] Table 2: Circuit etching results of various metal samples

[0052] As can be seen from the table above, by adjusting the distribution of metal foil grain size and thickness, this method prevents excessive etching by the chemical solution when fabricating fine circuits, preventing the circuits from forming an inverted trapezoidal shape. This reduces the contact area between the circuits and the substrate, resulting in a weakened bonding strength between the circuits and the substrate, making them more susceptible to delamination. In an embodiment of this application, to improve the bonding strength between the metal foil and the substrate, the second surface is made uneven, thereby increasing the contact area between the metal foil and the substrate.

[0053] In order to more intuitively understand the non-flat surface, optionally, a number of irregular raised structures are highlighted on one side of the second surface. The raised structure is provided with a plurality of extensions, and the extensions are raised and divergent outward relative to the outer contour of the raised structure. The non-flat surface formed by the raised structure and the extensions increases the contact area between the metal foil and the substrate, thereby realizing subsequent functions such as piercing, and thus ensuring the electrical performance of the circuit board. Of course, the non-flat surface formed by the above-mentioned raised structures and extensions is only a structural example. After the second surface is magnified several times, it can be displayed as a non-flat surface.

[0054] Furthermore, in the above embodiment, the roughness Rz of the non-flat surface is 0.4 to 3 μm. After a large number of experimental analyses, the applicant found that when the roughness Rz of the non-flat surface is in the range of 0.4 to 3 μm, the bonding force between the metal foil and the substrate is better. If the roughness Rz of the non-flat surface is less than 0.4 μm, the roughness is too low, the contact area is small, the bonding force between the metal foil and the substrate is low, and the metal foil is easy to fall off from the substrate; if the roughness Rz of the non-flat surface is greater than 3 μm, the roughness is too high, which increases the skin effect of the circuit and causes circuit signal transmission loss. Therefore, the roughness Rz of the non-flat surface can be 0.4 microns, 0.5 microns, 2 microns, 3 microns, etc., which is set according to the actual product design requirements and will not be further elaborated here.

[0055] Optionally, the metal foil of the application example is suitable for high-frequency circuits. The overall thickness of the metal foil will affect its use in high-precision, small, or lightweight electronic products, so it should not be too thick. In an optional embodiment, to ensure the performance of the metal foil, the overall thickness of the metal foil in this embodiment is 1 to 8 μm, for example, 1 micron, 2 microns, 3 microns, 7 microns, 8 microns, etc. Of course, the overall thickness of the metal foil can be adjusted according to actual product requirements, and further details will not be provided here.

[0056] In the embodiment of the present application, it is considered that during the application process, the outer surface of the metal foil is easily contaminated by objects such as moisture and dust in the air, and then an oxidation reaction occurs. For example, when the metal foil is in a high-temperature pressing process, the oxidation reaction causes pits and protrusions to form on the surface of the extremely thin metal foil during the pressing process, resulting in an uneven surface of the metal foil. This may lead to large line transmission losses in subsequent applications, and may also cause poor adhesion between the metal foil and application carriers such as circuit substrates when pressed, causing problems such as the metal foil tilting, blistering, and wrinkling. In addition, it is also possible that oxidation points fall off during the pressing process and adhere to the surface of the pressing plate of the press, causing contamination to the press, thereby affecting the subsequent pressing process. Therefore, in the embodiment of the present application, the metal foil also includes an anti-oxidation layer, and the anti-oxidation layer is provided on the first surface or / and the second surface. The anti-oxidation layer protects the outer surface of the metal foil from contamination by moisture, dust, and other particles in the air, maintaining a relatively dry and clean surface. It is also less susceptible to oxidation, effectively protecting the foil and simplifying environmental requirements for its transportation and storage, reducing the number of pre-use cleaning steps. The anti-oxidation layer is made of at least one of nickel, copper, zinc, and / or an alloy of at least one of these metals.

[0057] In an embodiment of the present application, the metal foil further includes a release layer disposed on the first surface. The release layer is designed to separate the metal foil from the metal foil by peeling, facilitating subsequent circuit fabrication. The release layer is made of a metallic material or a non-metallic material. The metallic material includes any one or more of molybdenum, titanium, and niobium; the non-metallic material includes silicon, graphite, an organic polymer material, etc. When the release layer is a non-metallic material, it may be in the form of a release layer. The release layer may include a silicone-free release agent release layer, a silicone oil release layer, or a nitrogen release layer. The release layer may be formed by applying and drying a release agent. In one embodiment, the release agent may include HDPE (high-density polyethylene) and PMA (propylene glycol methyl ether acetate) solvent. When using the two aforementioned release agents, the mass ratio of HDPE:PMA may be (1-5):7. In another embodiment, the release agent may include a fluorine-based release agent and a solvent; the volume ratio of the fluorine-based release agent:solvent may be (5-30):1. It can be understood that there is no special restriction on the types of the above solvents, and conventional release agent solvents in the field can be selected, such as butanone, which does not constitute a limitation on the present application. Optionally, when the material of the peeling layer is a metal material, the thickness of the peeling layer is 2 to 100 nm; or, when the material of the peeling layer is a non-metallic material, the thickness of the peeling layer is less than or equal to 1 μm. The specific thickness of the peeling layer can be set according to actual use requirements, and no further details are given here. The structural setting of the peeling layer in the embodiment of the application can ensure appropriate adhesive strength, while retaining a certain adhesive ability so that the metal foil will not be delaminated during the hot pressing process. In the embodiment of the present application, the metal foil also includes a carrier layer, which is arranged on the side of the peeling layer away from the first surface of the metal foil, and the carrier layer mainly plays a bearing role. The carrier layer is made of a metal material, and the metal material includes at least one of metal elements such as copper, aluminum, zinc, nickel, chromium, iron, silver, and gold.

[0058] It can be understood that the thickness of the carrier layer will affect the overall thickness of the metal foil. In order to ensure the overall performance of the metal foil and prevent the metal foil from being too thick, in the embodiment of the present application, the thickness of the carrier layer needs to be set according to actual usage requirements, and no further details will be given here.

[0059] In an embodiment of the present application, the metal material of the metal foil is a single metal material, which can be selected from any one of nickel, titanium, copper, silver, gold, platinum, iron, cobalt, chromium, tungsten, molybdenum, aluminum, magnesium, potassium, sodium, calcium, strontium, barium, germanium, antimony, lead, indium and zinc; in addition, the metal material of the metal foil can also be an alloy, for example, an alloy formed by any two of nickel, titanium, copper, silver, gold, platinum, iron, cobalt, chromium, tungsten, molybdenum, aluminum, magnesium, potassium, sodium, calcium, strontium, barium, germanium, antimony, lead, indium and zinc, which is set according to actual product design requirements and is not specifically limited here.

[0060] In an embodiment of the present application, the metal foil further includes a dielectric layer, and the dielectric layer is disposed on the surface of at least one of the metal foils.

[0061] Optionally, the material of the dielectric layer is selected from at least one of polyimide, epoxy resin, modified epoxy resin, modified acrylic resin, cyanate resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polyethylene naphthalate, polystyrene, polyvinyl chloride, polysulfone, polyphenylene sulfide, polyetheretherketone, polyphenylene oxide, polytetrafluoroethylene, liquid crystal polymer, polyoxadiazole, epoxy glass cloth, BT resin, metal, and ceramic.

[0062] In an embodiment of the present application, the metal foil further includes an adhesive layer, and the adhesive layer is disposed on the surface of at least one of the metal foils.

[0063] Optionally, the material of the adhesive layer is selected from at least one of polystyrene, vinyl acetate, polyester, polyethylene, polyamide, rubber or acrylic thermoplastic resins, phenolic, epoxy, thermoplastic polyimide, urethane, melamine or alkyd thermosetting resins, BT resin, and ABF resin.

[0064] It is understood that when the metal foil of the present application contains an anti-oxidation layer, the dielectric layer or adhesive layer can be provided on the anti-oxidation layer; when the metal foil of the present application contains a release layer and / or a carrier layer, the dielectric layer or adhesive layer can be provided on the surface of the metal foil away from the release layer and / or the carrier layer.

[0065] This embodiment provides a copper-clad laminate, which includes the metal foil described above.

[0066] Example 3

[0067] This embodiment provides a circuit board, which includes the metal foil or copper-clad laminate as described above.

[0068] Example 4

[0069] This embodiment provides a semiconductor material, which is prepared from the metal foil described above.

[0070] Example 5

[0071] This embodiment provides a negative electrode material for a battery. The negative electrode material includes the metal foil as described above and an electrode active material coated on a surface of the metal foil.

[0072] Example 6

[0073] This embodiment provides a battery, which includes the negative electrode material described above.

[0074] The metal foil, circuit board, copper-clad laminate, semiconductor material, negative electrode material for battery, and battery provided in the embodiments of the present application have the beneficial effects of at least one of the following:

[0075] (1) In order to prevent the etching solution from over-etching the circuit to form an inverted trapezoidal structure, the present application improves the metal foil for preparing the circuit, adjusts the metal grain size in the metal foil, sets the distribution of metal grains of different average grain sizes at different positions, and sets the average metal grain size of the first surface to be smaller than the average metal grain size of the second surface, thereby controlling the etching speed of the etching solution and preventing the metal foil from being over-etched to form an inverted trapezoidal structure of the circuit. On the one hand, it avoids the separation of the circuit and the substrate, thereby improving the peeling strength between the circuit and the substrate, and on the other hand, it ensures the stability of the circuit signal transmission;

[0076] (2) When the average grain size a1 of the metal in the thickness H1 is in the range of 0.05≤a1<0.2μm, the average grain size a2 of the metal in the thickness H2 is in the range of 0.2≤a2<0.3μm, and the average grain size a3 of the metal in the thickness H3 is in the range of 0.3≤a3≤2μm, the metal foil of the present application can have good corrosion resistance and side corrosion resistance;

[0077] (3) When the metal foil provided by the present application is selected, during the etching process, the etching solution will first come into contact with the H1 thickness. Due to the grain size limitation of the H1 thickness, the H1 thickness grain size is small and is easily etched. When the solution reaches the H2 thickness, the grain size of the H2 thickness is larger than that of the H2 thickness, which slows down the etching speed of the solution. Similarly, when the etching solution reaches the H3 thickness, the larger grain size of the H3 thickness further slows down the etching speed of the solution. Thus, side etching of the metal foil during the etching process is avoided, thereby effectively improving the quality of the metal foil and ensuring the electrical performance of the circuit board.

[0078] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A metal foil, characterized in that, It includes opposite first and second surfaces, and the average grain size of the metal on the first surface is smaller than that of the metal on the second surface.

2. The metal foil according to claim 1, characterized in that the range of the average metal grain size a1 of the H1 thickness is 0.05 ≤ a1 < 0.2 μm; the range of the average metal grain size a2 of the H2 thickness is 0.2 ≤ a2 < 0.3 μm; the range of the average metal grain size a3 of the H3 thickness is 0.3 ≤ a3 ≤ 2 μm; the H1 thickness is from the first surface to the position accounting for 15 - 25% of the overall thickness of the metal foil; the H2 thickness is from the position starting from the first surface accounting for 15 - 25% of the overall thickness of the metal foil to the position ending at the second surface accounting for 20 - 40% of the overall thickness of the metal foil; the H3 thickness is from the second surface to the position accounting for 20 - 40% of the overall thickness of the metal foil.

3. The metal foil according to claim 2, wherein The H1 thickness is 0.01 - 1 μm; or / and, the H2 thickness is 0.2 - 2 μm; and / or, the H3 thickness is 0.5 - 3 μm.

4. The metal foil according to claim 3, wherein, The second surface is an uneven surface.

5. The metal foil according to claim 4, wherein The roughness Rz of the uneven surface is 0.4 - 3 μm.

6. The metal foil according to claim 1, characterized in that, The metal foil includes an antioxidant layer, and the antioxidant layer is provided on the first surface or / and the second surface.

7. The metal foil according to claim 1, characterized in that, The metal foil further includes a release layer, and the release layer is provided on the first surface.

8. The metal foil according to claim 7, characterized in that, The metal foil further includes a carrier layer, and the carrier layer is provided on the side of the release layer away from the first surface.

9. The metal foil according to claim 8, characterized in that, The metal material of the metal foil is any one of nickel, titanium, copper, silver, gold, platinum, iron, cobalt, chromium, tungsten, molybdenum, aluminum, magnesium, potassium, sodium, calcium, strontium, barium, germanium, antimony, lead, indium, and zinc; or, the metal material is an alloy formed by any two of nickel, titanium, copper, silver, gold, platinum, iron, cobalt, chromium, tungsten, molybdenum, aluminum, magnesium, potassium, sodium, calcium, strontium, barium, germanium, antimony, lead, indium, and zinc.

10. The metal foil according to any one of claims 1 to 9, characterized in that, The metal foil further includes a dielectric layer, and the dielectric layer is provided on at least one of the surfaces of the metal foil.

11. The metal foil according to claim 10, wherein The material of the dielectric layer is selected from at least one of polyimide, epoxy resin, modified epoxy resin, modified acrylic resin, cyanate resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polyethylene naphthalate, polystyrene, polyvinyl chloride, polysulfone, polyphenylene sulfide, polyether ether ketone, polyphenylene ether, polytetrafluoroethylene, liquid crystal polymer, polyoxalylurea, epoxy glass cloth, BT resin, metal, and ceramic.

12. The metal foil according to any one of claims 1 to 9, characterized in that, The metal foil further includes an adhesive layer, and the adhesive layer is provided on at least one of the surfaces of the metal foil.

13. The metal foil according to claim 12, wherein The material of the adhesive layer is selected from at least one of styrene - based, vinyl acetate - based, polyester - based, polyethylene - based, polyamide - based, rubber - based, or acrylate - based thermoplastic resins, phenolic - based, epoxy - based, thermoplastic polyimide, urethane - based, melamine - based, or alkyd - based thermosetting resins, BT resin, and ABF resin.

14. A copper-clad laminate, characterized in that, It includes the metal foil according to any one of claims 1 - 13.

15. A circuit board, characterized in that, The circuit board includes the metal foil according to any one of claims 1 - 13 or the copper - clad laminate according to claim 14.

16. A semiconductor material, characterized in that, The semiconductor material is prepared from the metal foil described in any one of claims 1 to 13.

17. A negative electrode material applied to a battery, characterized in that, The negative electrode material includes the metal foil described in any one of claims 1 to 13 and an electrode active material coated on the surface of the metal foil.

18. A battery, characterized in that, The battery includes the negative electrode material according to claim 17.

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