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

Abstract

Disclosed in the present application are a metal foil, a circuit board, a copper-clad laminate, a negative-electrode material of a battery, and a battery. The metal foil comprises a first surface and a second surface opposite each other, wherein a metal average grain size of the first surface is greater than a metal average grain size of the second surface, and the ratio X of the metal average grain size of the first surface to the metal average grain size of the second surface is 1.5-20. With regard to the metal foil, circuit board, copper-clad laminate, negative-electrode material of a battery, and battery provided in the embodiments of the present application, by means of designing the structure of the metal foil and controlling the speed at which the metal foil is etched, the situation in which the electrical performance of the metal foil is affected due to the fact that a metal circuit is trapezoidal because of incomplete etching is avoided.

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 202311805408.1 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 202410148770.4 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 products such as flexible 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 advancement of electronic information technology, the use of multi-layer, complex, or high-density, fine-circuit PCBs in high-precision, miniaturized electronic products is increasing. High-precision electronic metal foil or double-sided roughened electrolytic metal foil is often used for the inner layers of these high-density, fine-circuit PCBs or multi-layer, complex PCBs. However, in actual use, the metal is not completely etched. This results in a trapezoidal metal pattern and reduced spacing between circuits. This can easily cause ion migration in high-frequency, high-speed signal transmission environments, affecting signal transmission and even causing distortion. Therefore, designing the metal foil and controlling its etching speed have become urgent technical challenges facing those skilled in the art.

[0006] Summary of the Invention

[0007] The present application provides metal foil, circuit board, copper-clad laminate, battery negative electrode material and battery. By designing the structure of the metal foil and controlling its etching speed, it is avoided that the metal circuit becomes trapezoidal due to incomplete etching, which affects the electrical performance of the metal foil.

[0008] In order to solve the above technical problems, an embodiment of the present application provides a metal foil, including a first surface and a second surface relative to each other, the average metal grain size of the first surface is larger than the average metal grain size of the second surface, and the ratio X of the average metal grain size in the first surface to the average metal grain size in the second surface is 1.5 to 20.

[0009] As one optional solution, the average metal grain size of the first surface is in the range of 0.8 to 2 μm, and the average metal grain size of the second surface is in the range of 0.1 to 0.5 μm.

[0010] As one of the optional solutions, the average metal grain size a1 of the thickness H1 is in the range of 0.8≤a1<1μm; the average metal grain size a2 of the thickness H2 is in the range of 0.4≤a2<0.8μm; the average metal grain size a3 of the thickness H3 is in the range of 0.1≤a3<0.4μm;

[0011] The thickness of H1 is from the first surface to 10-20% of the thickness of the entire metal foil; the thickness of H2 is from the first surface to 10-20% of the thickness of the entire metal foil to the second surface to 40-50% of the thickness of the entire metal foil; the thickness of H3 is from the second surface to 40-50% of the thickness of the entire metal foil.

[0012] As one optional solution, the thickness of H1 is 0.01 to 0.8 μm; or / and, the thickness of H2 is 0.5 to 4 μm; and / or, the thickness of H3 is 0.8 to 3 μm.

[0013] As an optional solution, the overall thickness of the metal foil is 1 to 15 μm.

[0014] As an optional solution, the second surface of the metal foil is a non-flat surface.

[0015] As an optional solution, the metal foil further 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 further includes a peeling layer, and the peeling layer is provided on the first surface.

[0017] As an optional solution, the metal foil further 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] Another embodiment of the present application provides a copper-clad laminate, which includes the metal foil as described above.

[0021] As an optional solution, the copper-clad laminate further includes a dielectric layer, and the dielectric layer is provided on the one side of at least one of the metal foils.

[0022] As one optional solution, the material of the dielectric layer is selected from at least one of polyimide, modified epoxy resin, modified acrylic 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, and BT resin.

[0023] As an optional solution, the copper-clad laminate further includes a second adhesive layer, and the second adhesive layer is provided on the one side of the metal foil.

[0024] As one optional solution, the material of the second 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.

[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] Another embodiment of the present application provides a negative electrode material for a battery, wherein the negative electrode material includes the metal foil as described above and an electrode active material coated on a surface of the metal foil.

[0028] Another embodiment of the present application provides a battery, which includes 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) The present application has conducted research on the average grain size of the metal foil and found that within a certain etching time, larger grains can control the etching speed of the etching solution to prevent excessive etching, while smaller grains can prevent the bottom of the circuit from being incompletely etched by the etching solution, causing the circuit to be trapezoidal, which affects the spacing between the circuits. Therefore, the embodiment of the present application designs the structure of the metal foil to control its etching speed, thereby avoiding incomplete etching causing the metal circuit to be trapezoidal, which affects the electrical performance of the metal foil; the applicant's research found that when the ratio X of the average metal grain size in the first surface to the average metal grain size in the second surface is 1.5 to 20, the circuit can be effectively prevented from being trapezoidal.

[0031] (2) With respect to the etching speed, the present application sets different metal grain sizes as follows: when the average metal grain size of the first surface is in the range of 0.8 to 2 μm and the average metal grain size of the second surface is in the range of 0.1 to 0.5 μm, it prevents the etching from being too fast and slows down the etching speed.

[0032] (3) The present application sets the grain size of the metal foil at different positions as follows: the average metal grain size a1 of the thickness H1> the average grain size a2 of H2> the average grain size a3 of H3, so that the etching speed of the solution is reduced when it contacts the metal foil H1 to prevent excessive corrosion. When the solution reaches H2, the corrosion speed can be accelerated due to its smaller grain size. When the solution reaches H3, its grain size is even smaller and is more susceptible to corrosion. However, since the contact time between H3 and the solution is shorter, excessive corrosion will not occur, and side corrosion will occur.

[0033] In summary, the circuits prepared using the metal foil of the present application will not be completely etched, resulting in the circuits being trapezoidal, thereby ensuring the standard spacing between the etched circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic diagram of a metal foil in one embodiment of the present application;

[0035] FIG2 is a schematic diagram of a metal foil in one embodiment of the present application;

[0036] FIG3 is a schematic diagram of a metal foil in one embodiment of the present application;

[0037] Reference numerals:

[0038] Wherein: 1. metal foil; 11. second surface; 111. metal grains; 2. anti-oxidation layer; 3. peeling layer; 4. carrier layer. DETAILED DESCRIPTION

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Example 1

[0044] 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 .

[0045] It should be noted that the average grain size of the above-mentioned metal can be measured by average distribution statistics through EBSD (electron backscatter diffraction), and the grain size in the thickness direction can be measured by EBSD (electron backscatter diffraction). The thickness ranges of H1, H2, and H3 are calculated based on the ratio of the overall thickness of the metal foil cross section measured by projection electron microscopy (TEM); the roughness of the subsequent second surface, which is a non-flat surface, can be measured by a roughness meter.

[0046] To avoid incomplete metal etching, the present applicant conducted extensive experiments on the average grain size of the metal foil. They found that within a certain etching time, larger grains can control the etching rate of the etching solution and prevent excessive etching, while smaller grains can prevent the bottom of the circuit from being completely etched by the etching solution, resulting in a trapezoidal shape and affecting the spacing between circuits. Based on the above conclusions, the embodiments of the present application set the metal grain size at different locations so that the average metal grain size on the first surface is larger than the average metal grain size on the second surface, and the ratio X of the average metal grain size on the first surface to the average metal grain size on the second surface is between 1.5 and 20. The applicant found that when the ratio of the grain size at the first and second surfaces is within this range, it can prevent the etching solution from being too rapid. When the ratio is less than 1.5, the grain size on the second surface is too large, resulting in incomplete etching of the circuit, leaving metal residue and forming a trapezoidal shape. When the ratio is greater than 20, the grain size on the second surface is too small, resulting in excessive etching and forming a trapezoidal shape.

[0047] As an optional embodiment of the present application, the ratio X of the average metal grain size in the first surface to the average metal grain size in the second surface can also range from 2 to 18, 4 to 15, or 6 to 10, and the ratio X can also be any value in the range of 1.5 to 20.

[0048] The present application is optimized within the above-mentioned ratio range, and it is found that when the ratio X range is 4 to 10, a better effect is achieved. Within this ratio range, the decreasing trend of the metal grains from the first surface to the second surface is more gradual, the etching speed of the solution is more uniform, and the etched metal surface is smoother, which is conducive to the electroplating of subsequent circuits.

[0049] In another embodiment, the present application defines a specific range of metal grain sizes on the first surface and the second surface. Experiments have shown that when the average metal grain size range of the first surface is 0.8 to 2 μm and the average metal grain size range of the second surface is 0.1 to 0.5 μm, the etching speed can be better controlled and the circuit will not form a trapezoid.

[0050] In another embodiment, the grain size at different thicknesses of the metal foil is set to: average grain size a1 at H1 > average grain size a2 at H2 > average grain size a3 at H3. That is, in the metal foil provided by the embodiment of the present application, the closer to the first surface, the larger the average grain size of the metal, and the closer to the second surface, the smaller the average grain size of the metal. This structure of the metal foil reduces the etching rate when the solution contacts the metal foil with a thickness of H1, preventing excessive etching. When the solution reaches the metal foil with a thickness of H2, the smaller grain size accelerates the etching rate. When the solution reaches the metal foil with a thickness of H3, the grain size is even smaller and more susceptible to etching. However, since the metal foil with a thickness of H3 is in contact with the solution for a shorter period of time, excessive etching does not occur. Therefore, circuits prepared using the metal foil of the embodiment of the present application will not be incompletely etched, resulting in a trapezoidal circuit shape. This ensures standard spacing between etched circuits and protects the electrical performance of subsequent circuit boards.

[0051] It can be understood that the average grain size of the metal at each thickness position needs to be ensured to decrease in the thickness direction in order to achieve the above-mentioned technical effects. Therefore, the specific values ​​of the average grain size of each thickness need to be randomly selected to ensure that it decreases gradiently in the thickness direction. No further details will be given here.

[0052] During the grain size screening process, it was discovered that if the grain size is too large, the etching time required is longer, which is detrimental to the efficiency of the production process; if the grain size is too small, especially for metal grains within the thickness H1, it cannot slow down the etching rate. Therefore, the grain size of the metal foil of this application gradually decreases along the thickness direction. In the early stage of etching, the grain size within the thickness H1 is larger, which slows down the etching rate and prevents excessive etching. In the middle stage of etching, the grains within the thickness H2 are smaller than those within the thickness H1 to facilitate the transition, which can speed up the etching rate. In the late stage of etching, due to the shorter etching time, the grain size within the thickness H3 is smaller, making it easier to etch, speeding up the etching of residual metal between the circuits, and preventing metal residue and incomplete etching that can cause circuit short circuits.

[0053] To ensure the ultimate etching effect of the etching solution, this embodiment of the present application optimizes and screens the grain size at each thickness. The final screened sizes are as follows: the average grain size a1 at thickness H1 in this embodiment is in the range of 0.8 ≤ a1 < 1 μm, and can be, for example, 0.8 μm, 0.85 μm, 0.87 μm, 0.88 μm, 0.9 μm, etc. Similarly, to ensure the effectiveness of the metal foil, the average grain size a2 at thickness H2 in this embodiment is in the range of 0.4 ≤ a2 < 0.8 μm, and can be, for example, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.78 μm, etc. Similarly, to ensure the effectiveness of the metal foil, the average grain size a3 at thickness H3 in this embodiment is in the range of 0.1 ≤ a3 < 0.4 μm, and can be, for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.35 μm, 0.39 μm, etc. Of course, the average grain size a1 of the thickness H1, the average grain size a2 of the thickness H2, and the average grain size a3 of the thickness H3 can be set according to actual product requirements, and no further details are given here.

[0054] It is understood that factors affecting the etching rate of the solution include not only the size of the metal particles 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 of grains of different sizes is particularly important. In an optional embodiment, to ensure the effectiveness of the metal foil, the thickness of H1 in this embodiment is 0.01 to 0.8 μm, for example, 0.01 micron, 0.02 micron, 0.5 micron, 0.7 micron, 0.8 micron, etc. Regarding the thickness of H2, to ensure the effectiveness of the metal foil, the thickness of H2 in this embodiment is 0.5 to 4 μm, for example, 0.5 micron, 0.7 micron, 1 micron, 2 micron, 3 micron, 4 micron, etc. Regarding the thickness of H3, to ensure the effectiveness of the metal foil, the thickness of H4 in this embodiment is 0.8 to 3 μm, for example, 0.8 micron, 1 micron, 2 micron, 3 micron, etc. The metal foil of the present embodiment has different metal particle sizes in different electroplated layers, and the thickness of each electroplated layer also varies. As described above, when the thickness of H1 is 0.01-0.8 μm, the thickness of H2 is 0.5-4 μm, and the thickness of H3 is 0.8-3 μm, the etching speed of the solution can be well controlled, ensuring that the circuit is not over-etched and maintains a good shape.

[0055] Illustratively, in one embodiment, the metal foil of the present application can be obtained by the following method: forming a layer of metal with a total thickness of 0.1 to 10 μm on a titanium roller by chemical deposition (for example, electroplating), and the average grain size a1 of the metal from the first surface to 10 to 20% of the thickness of the entire metal foil (H1 thickness) is in the range of 0.8 ≤ a1 < 1 μm; depositing another layer of metal on the aforementioned metal by chemical deposition (for example, electroplating), and the average grain size a2 of the metal from the first surface to 10 to 20% of the thickness of the entire metal foil to the second surface to 40 to 50% of the thickness of the entire metal foil (H2 thickness) is in the range of 0.4 ≤ a2 < 0.8 μm; depositing another layer of metal on the second metal by chemical deposition (for example, electroplating), and the average grain size a3 of the metal from the second surface to 40 to 50% of the thickness of the entire metal foil (H3 thickness) is in the range of 0.1 ≤ a3 < 0.4 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. The parameters of each metal sample are shown in Table 1 below:

[0056] Table 1: Parameters of various metal samples

[0057] Note: In this example, the thickness of the metal foil H2 is the distance from the first surface to the thickness of the entire metal foil (%) for each sample, and from the second surface to the thickness of the entire metal foil (%). The average metal grain size in this example was determined by measuring the area-weighted mean grain size within the thicknesses H1, H2, and H3 at any length on the cross-section of the metal foil using EBSD or SEM. This represents the average metal grain size for the entire distribution of thicknesses H1, H2, and H3.

[0058] Metal foil samples A and B were fabricated into 50cm x 60cm circuit board test panels. Fine lines with a line width and spacing of 25μm / 25μm and a line height of 25μm were produced using a modified semi-additive process (mSAP). Metallographic sections were used to examine the prepared lines to see if they exhibited trapezoidal shapes. The test results are shown in the table below:

[0059] Table 2: Circuit etching results of various metal samples

[0060] As can be seen from the above table, the present application adjusts the distribution of the metal foil grain size and the thickness in the metal foil to prevent the metal foil from being completely etched when preparing fine circuits, resulting in the metal circuits being trapezoidal and the circuit spacing being smaller, thereby affecting the high-frequency and high-speed signal transmission environment, easily causing ion migration, affecting signal transmission and even distortion.

[0061] Furthermore, in an embodiment of the present application, to enhance the bonding strength between the metal foil and the substrate, the second surface is configured as a non-flat surface, thereby increasing the contact area between the metal foil and the substrate. To more intuitively understand the non-flat surface, several irregular raised structures are optionally highlighted on one side of the second surface. These raised structures are provided with multiple extensions that radiate outward from the outer contour of the raised structures. The non-flat surface formed by these raised structures and extensions increases the contact area between the metal foil and the substrate, thereby enabling subsequent functions such as puncture, thereby 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 an example of a structure; magnifying the second surface several times will reveal it as a non-flat surface.

[0062] It is understandable that the metal foil of the present embodiment is suitable for high-density fine circuit boards and high-precision, small, or lightweight electronic products. Therefore, the thickness of the metal foil will affect its use in high-precision, small, or lightweight electronic products. 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 15 μm, for example, 1 micron, 2 microns, 3 microns, 4 microns, 5 microns, 6 microns, 10 microns, 11 microns, 12 microns, 13 microns, 14 microns, or 15 microns. Of course, the overall thickness of the metal foil can be set according to actual product requirements, and further details will not be given here.

[0063] 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.

[0064] In an embodiment of the present application, the metal foil further includes a release layer, which is disposed on the first surface. The function of the release layer is to separate 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, organic polymer materials, etc. When the release layer is a non-metallic material, it can be in the form of a release layer. The release layer includes a silicone-free release layer, a silicone oil release layer, or a nitrogen release layer. The release layer can be formed by applying and drying a release agent. In one embodiment, the release agent can 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 can be (1-5):7. In another embodiment, the release agent can include a fluorine-based release agent and a solvent; the volume ratio of the fluorine-based release agent:solvent can 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 application embodiment 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.

[0065] In an embodiment of the present application, the metal foil further comprises a carrier layer, which is disposed on a side of the release layer away from the first surface and primarily serves as a support. The carrier layer is made of a metal material, and the metal material comprises at least one of metal elements such as copper, aluminum, zinc, nickel, chromium, iron, silver, and gold.

[0066] 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.

[0067] Example 2

[0068] This embodiment provides a circuit board, which includes the metal foil or the copper-clad laminate of the present application.

[0069] This embodiment provides a copper-clad laminate, which includes the metal foil described above.

[0070] Furthermore, the copper-clad laminate further includes a dielectric layer, and the dielectric layer is provided on the one side of at least one of the metal foils.

[0071] Furthermore, the material of the dielectric layer is selected from at least one of polyimide, modified epoxy resin, modified acrylic 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, and BT resin.

[0072] Furthermore, the copper-clad laminate further includes a second adhesive layer, and the second adhesive layer is provided on the one side of the metal foil.

[0073] Furthermore, the material of the second 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.

[0074] Example 4

[0075] This embodiment provides a semiconductor material, which is prepared from the metal foil described above.

[0076] Example 5

[0077] 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.

[0078] Example 6

[0079] This embodiment provides a battery, which includes the negative electrode material described above.

[0080] 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:

[0081] (1) The present application has conducted research on the average grain size of the metal foil and found that within a certain etching time, larger grains can control the etching speed of the etching solution to prevent excessive etching, while smaller grains can prevent the bottom of the circuit from being incompletely etched by the etching solution, causing the circuit to be trapezoidal, which affects the spacing between the circuits. Therefore, the embodiment of the present application designs the structure of the metal foil to control its etching speed, thereby avoiding incomplete etching causing the metal circuit to be trapezoidal, which affects the electrical performance of the metal foil; the applicant's research found that when the ratio X of the average metal grain size in the first surface to the average metal grain size in the second surface is 1.5 to 20, the circuit can be effectively prevented from being trapezoidal.

[0082] (2) With respect to the etching speed, the present application sets different metal grain sizes as follows: when the average metal grain size of the first surface is in the range of 0.8 to 2 μm and the average metal grain size of the second surface is in the range of 0.1 to 0.5 μm, it prevents the etching from being too fast and slows down the etching speed.

[0083] (3) The present application sets the grain size of the metal foil at different locations to be: the average grain size a1 at thickness H1 > the average grain size a2 at thickness H2 > the average grain size a3 at thickness H3, so that the etching speed is reduced when the solution contacts the metal foil H1, preventing excessive etching. When the solution reaches the thickness H2, the etching speed is accelerated due to its smaller grain size. When the solution reaches the thickness H3, its grain size is even smaller and more susceptible to etching. However, since the contact time between the thickness H3 and the solution is shorter, the phenomenon of excessive etching will not occur. In summary, the circuits prepared using the metal foil of the present application will not be incompletely etched, resulting in the circuit being trapezoidal, thereby ensuring the standard spacing between the etched circuits.

[0084] 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, the average grain size of the metal on the first surface is larger than that on the second surface, and the ratio X of the average grain size of the metal in the first surface to that in the second surface is 1.5 to 20.

2. The metal foil according to claim 1, characterized in that, The average metal grain size range of the first surface is 0.8 to 2 μm, and the average metal grain size range of the second surface is 0.1 to 0.5 μm.

3. The metal foil according to claim 2, wherein the average metal grain size a1 of the H1 thickness ranges from 0.8 ≤ a1 < 1 μm; the average metal grain size a2 of the H2 thickness ranges from 0.4 ≤ a2 < 0.8 μm; the average metal grain size a3 of the H3 thickness ranges from 0.1 ≤ a3 < 0.4 μm; the H1 thickness is from the first surface to the position accounting for 10 to 20% of the overall thickness of the metal foil; the H2 thickness is from the position starting from the first surface accounting for 10 to 20% of the overall thickness of the metal foil to the position from the second surface accounting for 40 to 50% of the overall thickness of the metal foil; the H3 thickness is from the second surface to the position accounting for 40 to 50% of the overall thickness of the metal foil.

4. The metal foil according to claim 3, wherein The H1 thickness is 0.01 to 0.8 μm; or / and, the H2 thickness is 0.5 to 4 μm; and / or, the H3 thickness is 0.8 to 3 μm.

5. The metal foil according to claim 4, characterized in that, The overall thickness of the metal foil is 1 to 15 μm.

6. The metal foil according to claim 5, characterized in that, The second surface of the metal foil is a non-planar surface.

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

8. 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.

9. The metal foil according to claim 1, wherein 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.

10. The metal foil according to claim 9, wherein, 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.

11. A copper-clad laminate, characterized in that, The copper-clad laminate includes the metal foil according to any one of claims 1 to 10.

12. The copper-clad laminate according to claim 11, characterized in that, The copper-clad laminate further includes a dielectric layer, and the dielectric layer is provided on at least one of the surfaces of the metal foil.

13. The copper-clad laminate according to claim 12, wherein, The dielectric layer material is selected from at least one of polyimide, modified epoxy resin, modified acrylic resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polyethylene naphthalate, polystyrene, polyvinyl chloride, polysulfone, polyphenylene sulfide, polyether ether ketone, polyphenylene ether, polytetrafluoroethylene, liquid crystal polymer, polyoxalyl urea, epoxy glass cloth, and BT resin.

14. The copper-clad laminate according to claim 11, wherein, The copper-clad laminate further includes a second adhesive layer, and the second adhesive layer is provided on the surface of the metal foil.

15. The copper-clad laminate according to claim 14, wherein, The material of the second adhesive layer is selected from at least one of thermoplastic resins such as polystyrene-based, vinyl acetate-based, polyester-based, polyethylene-based, polyamide-based, rubber-based or acrylate-based, thermosetting resins such as phenolic-based, epoxy-based, thermoplastic polyimide, urethane-based, melamine-based or alkyd-based, BT resin, and ABF resin.

16. A circuit board, characterized in that, The circuit board includes the metal foil according to any one of claims 1 to 10 or the copper-clad laminate according to any one of claims 11 to 15.

17. A semiconductor material, characterized in that, The semiconductor material is prepared from the metal foil according to any one of claims 1 to 10.

18. A negative electrode material applied to a battery, characterized in that, The negative electrode material includes the metal foil according to any one of claims 1 to 10 and an electrode active material coated on the surface of the metal foil.

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

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