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

Abstract

The application discloses a metal foil, a circuit board, a copper-clad laminated board, a semiconductor, a negative material and a battery, the metal foil comprising opposite first and second surfaces, the first surface being a roughening treatment surface, and the second surface satisfying the following functional relationship between the root mean square roughness Rq of the second surface and the water drop angle Y of the second surface: Y=-8273.8*Rq+5309.1*Rq-814.52, Rq>0, 0Y<90°, and the correlation coefficient R of the functional relationship being 0.9735. 2 2 By optimizing the relationship between the root mean square roughness and the water drop angle of the other side surface of the metal foil opposite to the roughening treatment surface, the water drop angle and the roughness of the surface of the metal foil are both within a most reasonable range, the hydrophilicity of the surface of the metal foil is effectively improved, and the quality of the metal foil product is improved.​

Description

Technical Field

[0001] This invention relates to the field of metal foil technology, and more particularly to a metal foil, circuit board, copper-clad laminate, semiconductor, negative electrode material, and battery. Background Technology

[0002] Metal foil is an important material widely used in the electronics industry. It is one of the key materials for products such as flexible copper-clad laminates and printed circuit boards. In printed circuit boards, metal foil plays a vital role in conducting circuits and interconnecting components, and is known as the "neural network" for signal and power transmission and communication in electronic products. At the same time, metal foil is also an important raw material in chip packaging and new energy batteries.

[0003] The rapid development of microelectronics and new energy batteries has placed higher demands on the various physical properties of metal foils, such as hydrophilicity / hydrophobicity, high strength, ductility, and low surface roughness. Due to the different processing techniques and practical needs of different sides of the metal foil, the specific requirements for its physical properties are related to the specific application scenario. For example, when metal foil is used in the circuit board field, if the surface of the metal foil used for processing circuits is not sufficiently hydrophilic, it will lead to uneven reaction between the etching solution and the metal foil during the circuit board manufacturing process. This can result in localized over-etching or incomplete etching, leading to reduced etching efficiency and quality. Furthermore, in some circuit board factories, the metal foil material needs to be surface-cleaned before processing circuits. Since most cleaning agents are hydrophilic solvents, the hydrophilicity of the metal foil surface significantly affects the cleaning effect and efficiency. Meanwhile, the dry film lamination process before metal foil etching requires a certain degree of hydrophilicity to ensure a tight and complete bond with the dry film. Otherwise, poor adhesion can lead to etching solution seeping into gaps, causing etching in areas that shouldn't be etched. The dry film fails to protect non-etched areas, resulting in decreased product etching quality and increased defect rates. Furthermore, when metal foil is used in new energy batteries, the surface needs to adhere to the battery electrolytic reaction materials. Insufficient hydrophilicity of the metal foil surface can prevent the electrolytic reaction materials from spreading evenly, leading to poor or non-firm adhesion. This makes the materials prone to detachment during battery charging and discharging, resulting in decreased battery quality, performance, and safety. Current research on the hydrophilicity of metal foil surfaces is limited, leaving those skilled in the art facing numerous adverse consequences due to poor surface hydrophilicity. Summary of the Invention

[0004] The purpose of this invention is to provide a metal foil, circuit board, copper-clad laminate, semiconductor, negative electrode material, and battery. By optimizing the relationship between the root mean square roughness and the water droplet angle of the surface opposite the roughened surface of the metal foil, the hydrophilicity of the metal foil surface is effectively improved, thereby improving the quality of the metal foil product.

[0005] To achieve the above objectives, embodiments of the present invention provide a metal foil, including a first surface and a second surface opposite to each other. The first surface is a roughened surface, and the root mean square roughness Rq of the second surface and the water droplet angle Y of the second surface satisfy the following functional relationship:

[0006] Y = -8273.8 × Rq 2 +5309.1×Rq-814.52, Rq>0, 0<Y<90°, and the

[0007] The correlation coefficient R of the functional relationship 2 It is 0.9735.

[0008] As an improvement to the above scheme, the water droplet angle Y of the second surface is in the range of 5° to 38°.

[0009] As an improvement to the above scheme, the root mean square roughness Rq of the second surface is 0.26 to 0.34 μm.

[0010] As an improvement to the above scheme, the roughness Rz of the first surface is 1.5 to 1.95 μm.

[0011] As an improvement to the above scheme, the water droplet angle X on the first surface is greater than the water droplet angle Y on the second surface, and the water droplet angle X on the first surface is less than or equal to 6 times the water droplet angle Y on the second surface.

[0012] As an improvement to the above solution, the metal foil includes a conductive layer, one side of which is the first surface and the other side of which is the second surface.

[0013] As an improvement to the above scheme, the material of the conductive layer includes at least one of the following metal elements: copper, aluminum, zinc, nickel, silver, titanium, gold, chromium, and cobalt, and / or an alloy of at least one of them.

[0014] As an improvement to the above scheme, the thickness of the conductive layer is 1 to 6 μm.

[0015] As an improvement to the above solution, the metal foil further includes a carrier layer disposed on the second surface of the conductive layer.

[0016] As an improvement to the above scheme, the material of the carrier layer includes at least one of the following metallic elements: copper, aluminum, zinc, nickel, chromium, iron, silver and gold, in which case the thickness of the carrier layer is 5 to 50 μm; or, the material of the carrier layer is an organic thin film, in which case the thickness of the carrier layer is 10 to 100 μm.

[0017] As an improvement to the above solution, the metal foil further includes a release layer disposed between the carrier layer and the conductive layer.

[0018] As an improvement to the above scheme, the material of the release layer is a metallic material, and the thickness of the release layer is 2 to 100 nm; or, the material of the release layer is a non-metallic material, and the thickness of the release layer is less than or equal to 1 μm.

[0019] This invention also provides a circuit board, including a circuit board substrate and a metal foil as described in any of the above embodiments; the roughened surface of the metal foil is pressed against the circuit board substrate.

[0020] This invention also provides a copper-clad laminate, the copper-clad laminate comprising the metal foil as described in any of the preceding claims.

[0021] This invention also provides a semiconductor material, which includes a metal foil as described in any of the preceding embodiments.

[0022] This invention also provides a negative electrode material for use in batteries, the negative electrode material comprising a metal foil as described in any of the preceding embodiments.

[0023] The present invention also provides a battery, wherein the negative electrode material of the battery comprises a metal foil as described in any of the preceding embodiments.

[0024] Compared with the prior art, the metal foil disclosed in the embodiments of the present invention, as well as the circuit board, copper-clad laminate, semiconductor, negative electrode material and battery using the metal foil, wherein the metal foil has a first surface that is roughened, and a second surface opposite to the first surface, and the root mean square roughness Rq of the second surface and the water droplet angle Y of the second surface satisfy the following functional relationship: Y = -8273.8 × Rq 2+5309.1×Rq-814.52, Rq>0, 0<Y<90°, gives the second surface of the metal foil excellent hydrophilicity. When the metal foil is used in the field of printed circuit boards, it needs to be bonded to a dry film for circuit etching in subsequent processes. The greater the hydrophilicity of the second surface 2 of the metal foil, the stronger the adhesion between it and the hydrophilic dry film. This effectively prevents the etching solution from seeping into the gaps due to poor adhesion between the metal foil surface and the dry film, causing etching in places that should not be etched. Thus, the protection of the circuit is better during the circuit etching process, avoiding the occurrence of defective etching and ensuring the etching yield of the circuit. At the same time, it ensures the improvement of the cleaning effect and efficiency of the metal foil before application. In addition, during the etching process, the higher the hydrophilicity of the second surface of the metal foil, the easier it is for the etching solution to spread, and the more uniform the reaction between the etching solution and the metal foil. Over-etching or incomplete etching will not occur. The faster the etching rate of the metal foil, the higher the production efficiency, and thus the lower the production cost. Furthermore, when metal foil is used in new energy batteries, its excellent hydrophilic surface ensures good adhesion between the metal foil and the electrolytic material. This prevents the electrolytic material from detaching from the metal foil surface or bubbling during battery operation, thus guaranteeing battery performance, safety, and operational stability. In addition, this embodiment of the invention further optimizes the water droplet angle Y of the second surface to 5°–38° and / or the root mean square roughness Rq of the second surface to 0.26–0.34 μm, ensuring that the water droplet angle and roughness of the second surface of the metal foil are within an optimal range. This results in superior hydrophilicity of the second surface, further optimizing the structure of the metal foil and improving its quality. When the metal foil is used in the field of new energy batteries, its good hydrophilicity helps to spread the negative electrode active material evenly, resulting in tight adhesion and preventing detachment during battery charging and discharging reactions, thereby improving the battery's reaction stability and safety. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the first type of metal foil provided in the embodiments of the present invention;

[0026] Figure 2 This is a top-view electron microscope image of the first type of metal foil provided in the embodiments of the present invention;

[0027] Figure 3 This is a schematic diagram of the structure of the second type of metal foil provided in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the structure of the third type of metal foil provided in the embodiments of the present invention;

[0029] Figure 5 This is a schematic diagram of the structure of the fourth type of metal foil provided in the embodiments of the present invention;

[0030] Figure 6 This is a schematic diagram of the structure of the fifth type of metal foil provided in the embodiments of the present invention;

[0031] Figure 7 This is a schematic diagram of the structure of the sixth type of metal foil provided in the embodiments of the present invention;

[0032] Figure 8 This is a schematic diagram of the structure of the seventh type of metal foil provided in the embodiments of the present invention;

[0033] Figure 9 This is a schematic diagram of the structure of the eighth type of metal foil provided in the embodiments of the present invention;

[0034] Figure 10 This is a schematic diagram of the structure of the ninth type of metal foil provided in the embodiments of the present invention;

[0035] Figure 11 This is a schematic diagram of the structure of the eighth type of metal foil provided in the embodiments of the present invention;

[0036] Figure 12 This is a schematic diagram of the structure of the ninth type of metal foil provided in the embodiments of the present invention;

[0037] Wherein, 1. First surface; 2. Second surface; 3. Conductive layer; 4. Carrier layer; 41. First filler particles; 5. Release layer; 51. Second filler particles; 6. Adhesive layer; 7. First anti-oxidation layer; 8. Second anti-oxidation layer; 9. Resin layer. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the description of the specification and claims, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present invention, and do not indicate or imply that the device or component 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 on the embodiments of the present invention.

[0040] Furthermore, the terms "first," "second," etc., used in the specification and claims are used only to distinguish the description of the same technical features and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated, nor necessarily the order of description or chronological sequence. Where appropriate, the terms are interchangeable. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature.

[0041] Example 1

[0042] See Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the structure of the first type of metal foil provided in the embodiments of the present invention; Figure 2 This is a top-view electron microscope image of the first type of metal foil provided in an embodiment of the present invention. The embodiment of the present invention provides a metal foil including a first surface 1 and a second surface 2 opposite to each other, wherein the first surface 1 is a roughened surface.

[0043] It should be noted that the surface of the metal foil subjected to the roughening process is called the roughened surface. In practical applications, the metal foil can be used in various fields, such as circuit boards and batteries. During application, the metal foil can be pressed against the application carrier through the roughened surface of the metal foil. In one optional embodiment, when the metal foil is used in the circuit board field, it is thermally bonded to the circuit board substrate through the roughened surface; in another optional embodiment, when the metal foil is used in the battery field, it serves as the negative electrode material of the battery, and its two side surfaces are bonded to the negative electrode active material in the negative electrode material.

[0044] On the other side opposite the roughened surface, i.e., the second surface 2, it is usually bonded to other peelable material layers, such as carrier layers or release layers, during the production process. In the application process, such as when it is applied to the circuit board field, after the peelable material layers are peeled off, subsequent circuit etching and other processes are performed on the second surface 2. At this time, if the hydrophilicity of the metal foil surface is insufficient, a series of adverse problems will occur, such as: 1) During the cleaning process before etching, the hydrophilic cleaning solvent will not be evenly spread, affecting the cleaning effect and efficiency; 2) During the dry film application process before etching, since the dry film is mostly a hydrophilic photosensitive material, if the surface of the metal foil is not hydrophilic enough, the foil and the dry film will not be able to adhere completely and tightly, the etching solution will seep into the gaps, the dry film will fail to protect the non-etched areas, and the areas that should not be etched will be etched; 3) During the etching process, the reaction between the etching solution and the metal foil will be uneven during the circuit board manufacturing process, resulting in local over-etching or incomplete etching, which will lead to a decrease in product etching quality and an increase in the defect rate. When applied in the field of new energy batteries, the second surface 2 is used to bond the battery electrolytic reaction materials. If the surface of the metal foil lacks sufficient hydrophilicity, the electrolytic reaction materials will be difficult to bond or will not bond tightly, making them prone to detachment during the battery charging and discharging process. This leads to a decrease in battery quality and performance, and a reduction in safety. Therefore, in practical applications, the hydrophilicity of the second surface 2 of the metal foil is required to be high.

[0045] In this embodiment of the invention, the root mean square roughness Rq of the second surface and the water droplet angle Y of the second surface satisfy the following functional relationship: Y = -8273.8 × Rq 2 +5309.1×Rq-814.52, Rq>0, 0<Y<90°, and the correlation coefficient R of the functional relationship. 2 It is 0.9735.

[0046] It should be noted that the root mean square roughness Rq is specifically the root mean square value of the profile ordinate Z(x) within a sampling length. The ordinate Z(x) refers to the distance from each point on the profile to the profile centerline, which can fully reflect the height characteristics of the surface micro-geometry.

[0047] Since the hydrophilicity of a metal foil surface is related to the size of the droplet angle γ and the surface roughness, generally, the smaller the droplet angle γ, the stronger the hydrophilicity, and the larger the droplet angle γ, the weaker the hydrophilicity; similarly, the smaller the roughness, the stronger the hydrophilicity, and the larger the roughness, the weaker the hydrophilicity. In this embodiment of the invention, by fitting the functional relationship between the root mean square roughness Rq and the droplet angle γ, the root mean square roughness Rq of the second surface 2 has a certain functional correlation with the droplet angle γ. When the droplet angle γ and the root mean square roughness Rq of the second surface 2 of the metal foil simultaneously satisfy the above functional relationship, the second surface 2 can simultaneously have a reasonable roughness range and a reasonable droplet angle range, resulting in better hydrophilicity of the second surface 2, which meets the requirements for the hydrophilicity of the metal foil surface. Furthermore, the correlation coefficient R of the functional relationship... 2 The correlation coefficient is 0.9735, which is close to 1, indicating that the regression fit is good and the linear relationship between the root mean square roughness Rq and the teardrop angle Y is strong.

[0048] Using the technical means of this invention, the second surface 2 of the metal foil has excellent hydrophilicity. When the metal foil is applied in the field of printed circuit boards, it needs to be bonded to a dry film for circuit etching in subsequent processes. The greater the hydrophilicity of the second surface 2 of the metal foil, the stronger the bonding strength with the hydrophilic dry film. This effectively prevents the etching solution from seeping into the gaps due to poor bonding between the metal foil surface and the dry film, causing etching in places that should not be etched. Thus, the protection of the circuit is better during the circuit etching process, avoiding the occurrence of defective etching and ensuring the etching yield of the circuit. At the same time, during the etching process, the higher the hydrophilicity of the second surface 2 of the metal foil, the easier it is for the etching solution to spread, and the more uniform the reaction between the etching solution and the metal foil. Over-etching or incomplete etching will not occur, and the etching rate of the metal foil will be faster, improving production efficiency and reducing production costs. Moreover, when metal foil is used in new energy batteries, its excellent hydrophilic surface ensures good adhesion between the metal foil and the electrolytic material. This prevents the electrolytic material from falling off or separating and bubbling during battery operation, thus ensuring the battery's performance, safety, and operational stability.

[0049] In a preferred embodiment, the water droplet angle Y of the second surface is 5° to 38°.

[0050] In this embodiment of the invention, based on the fact that the water droplet angle Y and the root mean square roughness Rq of the second surface of the metal foil satisfy the above functional relationship, the numerical range of the water droplet angle Y of the second surface 2 is further optimized. The water droplet angle Y of the second surface is between 5° and 38°, for example, it can be 5°, 6°, 8°, 10°, 12°, 15°, 18°, 20°, 21°, 22°, 23°, 24°, 25°, 26°, 27°, 28°, 29°, 30°, 31°, 32°, 33°, 34°, 35° or 38°. Of course, the specific value of the water droplet angle Y of the second surface can be set according to the actual application requirements, which will not be elaborated further here. This makes the second surface 2 have excellent hydrophilicity, which is very suitable for application in different technical fields where hydrophilicity is required, and enables the metal foil to adhere well to different application carriers through the second surface 2. Meanwhile, the second surface 2 has a reasonable surface roughness. The roughness of the second surface 2 is not too high, thereby avoiding unnecessary transmission loss when the metal foil is applied to the circuit board field. It also simplifies the manufacturing process of the metal foil products and improves the quality of the metal foil products in all aspects.

[0051] In a preferred embodiment, the root mean square roughness Rq of the second surface is 0.26–0.34 μm.

[0052] In this embodiment of the invention, based on the above-mentioned functional relationship between the water droplet angle Y and the root mean square roughness Rq of the second surface 2 of the metal foil, the numerical range of the root mean square roughness Rq of the second surface 2 is further optimized. The root mean square roughness Rq of the second surface 2 is between 0.26 and 0.34 μm, for example, it can be 0.26 μm, 0.27 μm, 0.28 μm, 0.29 μm, 0.30 μm, 0.31 μm, 0.32 μm, 0.33 μm or 0.34 μm. Of course, the specific value of the root mean square roughness Rq of the second surface 2 can be set according to the actual usage requirements, which will not be elaborated further here.

[0053] By employing the technical means of this invention, the second surface 2 of the metal foil is controlled within a reasonable roughness range. The roughness of the second surface 2 is not too high, thereby avoiding unnecessary transmission losses when the metal foil is applied to circuit boards and simplifying the manufacturing process of the metal foil products. Furthermore, within this roughness range, while satisfying the functional relationship between the root mean square roughness Rq and the droplet angle Y, the second surface 2 also possesses a reasonable droplet angle Y, giving it excellent hydrophilicity. This makes it highly suitable for applications requiring hydrophilicity in various technical fields, allowing the metal foil to adhere well to different application carriers through the second surface 2.

[0054] In a preferred embodiment, the roughness Rz of the first surface is 1.5 to 1.95 μm.

[0055] In this embodiment of the invention, the first surface 1 is a roughened surface that has undergone a roughening process. The roughening process includes setting a plurality of roughening particles 11 on the first surface 1. The roughening particles 11 refer to protrusions formed on the corresponding surface of the metal foil after the roughening process. It should be noted that due to differences in process methods and parameters, the roughening particles 11 can also be in other shapes such as clusters, ice-like structures, stalactite-like structures, or dendritic structures, and are not limited to the above shapes. Any roughening particles 11 that provide surface roughness to the metal foil are within the scope of protection of this invention. Furthermore, in specific implementations, a material layer of the metal foil can be formed first, and then the roughening particles 11 can be formed on the material layer through other processes. Of course, the material layer of the metal foil and the roughening particles 11 can also be an integral structure formed by a one-time molding process. It should be noted that the material of the roughening particles 11 can be the same as or different from the material of the metal foil, and is not limited here.

[0056] Of course, the roughening process also includes setting the surface of the metal foil as an undulating, non-flat surface, or setting several tiny bumps and depressions on the surface of the metal foil, or a combination of at least two of the above three implementation methods, none of which constitute a limitation of the present invention.

[0057] It should be noted that the roughness Rz is the sum of the average of the n largest profile peak heights and the average of the n largest profile valley depths within the sampling length, where n ≥ 1; preferably, n = 5. The roughness Rz can fully reflect the peak height of the profile.

[0058] After the roughening process, the roughness Rz of the first surface 1 is between 1.5 and 1.95 μm, for example, it can be 1.5 μm, 1.55 μm, 1.6 μm, 1.65 μm, 1.7 μm, 1.75 μm, 1.8 μm, 1.85 μm, 1.9 μm or 1.95 μm. Of course, the specific value of the roughness Rz of the first surface 1 can be set according to the actual usage requirements, which will not be elaborated further here.

[0059] By employing the technical means of this invention, the first surface 1 has a reasonable roughness range, thereby effectively improving the roughened surface of the metal foil. This effectively enhances the adhesion of the metal foil to the circuit board substrate or the negative electrode active material and other application carriers during subsequent applications. At the same time, it ensures a reasonable peel strength between the metal foil and the circuit board substrate or the negative electrode active material and other application carriers, reducing the occurrence of blistering and cracking on the metal foil surface, while avoiding increasing the high-frequency signal transmission loss of the roughened surface.

[0060] In a preferred embodiment, the water droplet angle X on the first surface is greater than the water droplet angle Y on the second surface, and the water droplet angle X on the first surface is less than or equal to 6 times the water droplet angle Y on the second surface, that is, X≤6Y.

[0061] In this embodiment of the invention, the water droplet angle X of the first surface 1 is much larger than the water droplet angle Y of the second surface 2. When X is greater than 90°, the first surface 1 is hydrophobic relative to the second surface 2. That is, the roughened surface of the metal foil is hydrophobic. When the metal foil is applied to printed circuit boards and other applications requiring hydrophobicity, it can effectively prevent pollutants such as moisture in the air from adsorbing onto the roughened surface. This effectively solves various problems caused by oxidation of the roughened surface of the metal foil due to the adsorption of pollutants such as moisture in the air onto the roughened surface, which can lead to a decrease in circuit conductivity or even insulation. It also reduces the oxidation and contamination of the metal foil surface, simplifies the environmental requirements for the transportation and storage of the metal foil, and reduces the cleaning process before the application of the metal foil. Meanwhile, by optimizing the hydrophobicity of the roughened surface, problems such as poor bonding and loose adhesion between the roughened surface and the resin adhesive during the subsequent lamination process of the metal foil and the circuit board substrate can be avoided, which would lead to reduced adhesion to the substrate. This ensures excellent bonding between the metal foil and the circuit board substrate, as well as full adhesion with the adhesive, reducing the possibility of blistering and board bursting, increasing the yield of products, and saving production costs.

[0062] When X is less than 90°, the metal foil can be well applied to lithium-ion batteries and used as a current collector for their negative electrode material. Specifically, by optimizing the surface hydrophilicity, the hydrophilic negative electrode active material can be well spread on the surface of the metal foil, promoting good adhesion between the active material and the metal foil, reducing the shedding of the negative electrode active material, ensuring its stability and reliability in subsequent electrochemical reactions, and improving the battery's lifespan and safety.

[0063] Specific examples were used to test the etching rate of ordinary metal foil and the metal foil with the structure of the present invention, the protection of the metal foil surface by the dry film, and the scrap rate of the etched lines.

[0064] In this embodiment of the invention, the specific methods for testing the root mean square roughness Rq and water droplet angle Y of the second surface of the metal foil are as follows:

[0065] The metal foil sample was cut into 100mm × 150mm pieces. After pressing the first surface 1 of the metal foil onto the adhesive surface of the cover film, the carrier layer on the second surface 2 was peeled off. The roughness Rq on the second surface was measured using a contact roughness tester or a white light interferometer, and recorded as the root mean square roughness Rq value of the second surface. The water droplet angle value of the second surface of the metal foil sample was measured using a water droplet angle tester and recorded as the water droplet angle Y value of the second surface.

[0066] Let A represent the metal foil product of this invention. Four metal foil samples (A1, A2, A3, and A4) were randomly selected and compared with commercially available ordinary metal foil product B.

[0067] Metal foil A1: Water droplet angle Y = 34.021° on the second surface, root mean square roughness Rq = 0.34;

[0068] Metal foil A2: Water droplet angle on the second surface Y = 37.024°, root mean square roughness Rq = 0.328;

[0069] Metal foil A3: The water droplet angle on the second surface is Y = 35.7°, and the root mean square roughness is Rq = 0.31;

[0070] Metal foil A4: Water droplet angle on the second surface Y = 6.537°, root mean square roughness Rq = 0.26;

[0071] Metal foil B: The water droplet angle Y on the side opposite to the roughened surface is 89.65°, and the root mean square roughness Rq is 0.332.

[0072] The test data and comparison results are shown in Table 1:

[0073] Table 1

[0074]

[0075]

[0076] Therefore, compared with ordinary metal foils sold on the market, the metal foil using the structure of the present invention has a lower etching rate when performing line etching on the second surface, better protection of the second surface of the metal foil by the dry film, and a lower scrap rate of the etched lines. All its performance is superior to ordinary commercially available products.

[0077] This invention provides a metal foil having a first surface that has been roughened, and a second surface opposite to the first surface. The root mean square roughness Rq of the second surface and the water droplet angle Y of the second surface satisfy the following functional relationship: Y = -8273.8 × Rq 2 +5309.1×Rq-814.52, Rq>0, 0<Y<90°, gives the second surface of the metal foil excellent hydrophilicity. When the metal foil is used in the field of printed circuit boards, it needs to be bonded to a dry film for circuit etching in subsequent processes. The greater the hydrophilicity of the second surface 2 of the metal foil, the stronger the bonding strength with the hydrophilic dry film. This effectively prevents the etching solution from seeping into the gaps due to poor bonding between the metal foil surface and the dry film, causing etching in places that should not be etched. Thus, the circuit is better protected during the etching process, avoiding the occurrence of defective etching and ensuring the etching yield of the circuit. At the same time, during the etching process, the higher the hydrophilicity of the second surface of the metal foil, the easier it is for the etching solution to spread, and the more uniform the reaction between the etching solution and the metal foil. Over-etching or incomplete etching will not occur. The etching rate of the metal foil is faster, improving production efficiency and reducing production costs. Furthermore, when metal foil is used in new energy batteries, its excellent hydrophilic surface ensures good adhesion between the metal foil and the electrolytic material. This prevents the electrolytic material from detaching from the metal foil surface or bubbling during battery operation, thus guaranteeing battery performance, safety, and operational stability. In addition, this embodiment of the invention further optimizes the water droplet angle Y of the second surface to 5°–38° and / or the root mean square roughness Rq of the second surface to 0.26–0.34 μm. This ensures that the water droplet angle and roughness of the second surface of the metal foil are within an optimal range, resulting in superior hydrophilicity, optimized metal foil structure, and improved metal foil quality.

[0078] For a preferred embodiment, see Figure 3 This is a schematic diagram of the structure of a second type of metal foil provided in an embodiment of the present invention. The metal foil includes a conductive layer 3, one side of which is the first surface 1, i.e., the roughened surface, and the other side of which is the second surface 2.

[0079] In this embodiment of the invention, the main structure of the metal foil includes a conductive layer 3. In practical applications, such as in the field of circuit boards, the conductive layer 3 is thermally bonded to the substrate of the circuit board. Similarly, in the field of batteries, the metal foil serves as the negative electrode material, and the conductive layer 3 is thermally bonded to the negative electrode active material. The side of the conductive layer 3 used for bonding to the substrate of the circuit board or the negative electrode active material is configured as the roughened surface, thereby increasing the adhesion of the conductive layer 3 and reducing bubbling, wrinkling, and cracking during bonding.

[0080] The conductive layer 3 is composed of a metal with good conductivity and low resistivity. The conductive layer 3 includes a single-metal conductive layer and / or an alloy conductive layer; wherein the single-metal conductive layer is made of any one of copper, aluminum, zinc, nickel, silver, gold, chromium and cobalt, and the alloy conductive layer is made of any two or more of copper, aluminum, zinc, nickel, silver, titanium, gold, chromium and cobalt, or it can be made of any two or more of copper, aluminum, zinc, nickel, silver, titanium, gold, chromium and cobalt and other materials.

[0081] Preferably, the conductive layer 3 is an ultra-thin metal layer with a thickness of 1–6 μm. More preferably, it is 1–5 μm, making the metal foil product thinner and lighter, and more practical.

[0082] In practice, a conductive layer 3 of a metal foil can be formed first, and then coarsened particles 11 can be formed on the conductive layer 3 through other processes. Alternatively, the conductive layer 3 of the metal foil and the coarsened particles 11 can be formed as a single integral structure through a one-step molding process. It should be noted that the material of the coarsened particles 11 can be the same as, partially the same as, or different from, the material of the conductive layer 3; this is not limited here.

[0083] For a preferred embodiment, see Figure 4 This is a schematic diagram of the structure of a third type of metal foil provided in an embodiment of the present invention. The metal foil includes a conductive layer 3 and a carrier layer 4, wherein the carrier layer 4 is disposed on the side of the conductive layer 3 that is not the first surface 1.

[0084] In this embodiment of the invention, the metal foil has a multilayer structure, including a conductive layer 3 and a carrier layer 4 stacked sequentially. One side of the conductive layer 3 is the first surface 1, which is the roughened surface, and the other side of the conductive layer 3 is the second surface 2. The carrier layer 4 is disposed on the second surface 2 of the conductive layer 3.

[0085] The carrier layer 4 can be used to support and protect the conductive layer 3, so that the conductive layer 3 is not damaged by external contact or collision. After the metal foil is pressed with the circuit board at high temperature, the carrier layer 4 needs to be peeled off.

[0086] The carrier layer 4 is made of metallic or non-metallic materials. The metallic materials include at least one of the following metallic elements: copper, aluminum, zinc, nickel, chromium, iron, silver, and gold; the non-metallic materials include organic thin films, etc. Since the carrier layer 4 mainly serves a load-bearing function, it needs a certain thickness. When the carrier layer 4 is a metallic material, the thickness of the carrier layer is preferably 5-50 μm, more preferably 8-35 μm, for example, it can be 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm, 35 μm, etc. When the carrier layer is a non-metallic material such as an organic thin film, the thickness of the carrier layer is preferably 10-100 μm, for example, it can be 10 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc. Of course, the specific thickness of the carrier layer 4 can be set according to the actual usage requirements, which will not be elaborated further here.

[0087] The carrier layer 4 can be separated from the conductive layer 3 by a peelable or non-peelable method. When the carrier layer 4 is removed by a non-peelable method, such as laser etching, chemical etching, polishing, or plasma removal, the method can be such as manual peeling or removal using mechanical equipment.

[0088] Preferably, see Figure 5 This is a schematic diagram of the structure of a fourth type of metal foil provided in an embodiment of the present invention. The metal foil includes a conductive layer 3 and a carrier layer 4, and further includes a release layer 5, which is disposed between the carrier layer 4 and the conductive layer 3. That is, the metal foil includes a carrier layer 4, a release layer 5, and a conductive layer 3 stacked sequentially, and the side of the conductive layer 3 away from the release layer 5 is the first surface 1, and the side of the conductive layer 3 close to the release layer 5 is the second surface 2.

[0089] In this embodiment of the invention, when the carrier layer 4 is removed by peeling, the peeling method is: to remove it by peeling off the peeling layer 5, that is, to separate the carrier layer 4 from the conductive layer 3 by peeling off the peeling layer 5.

[0090] Meanwhile, the presence of the release layer can prevent metal migration between the conductive layer 3 and the carrier layer 4. Moreover, the release layer 5 can cover or fill the uneven surface of the carrier layer 4, making the conductive layer 3 formed on the other surface of the release layer 5 more flat, uniform and dense, reducing the occurrence of pinholes, which is beneficial to the fabrication of subsequent circuits.

[0091] Preferably, the release layer 5 is made of a metallic or non-metallic material. The metallic material includes any one or more of molybdenum, titanium, and niobium; the non-metallic material includes silicon, graphite, organic polymers, 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 agent release layer, a silicone oil release layer, or a nitrogen-based release layer. The release layer can be formed by coating 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, etc. When using the above two release agents, the mass ratio of HDPE to PMA is preferably (1-5):7. In another embodiment, the release agent may include a fluorinated release agent and a solvent; wherein the volume ratio of fluorinated release agent to solvent is preferably (5-30):1. It is understood that there are no special limitations on the types of solvents mentioned above; conventional release agent solvents in the art can be used, such as butanone, which does not constitute a limitation of the present invention.

[0092] Preferably, when the material of the release layer 5 is a metallic material, the thickness of the release layer is 2–100 nm; or, when the material of the release layer is a non-metallic material, the thickness of the release layer is less than or equal to 1 μm. The specific thickness of the release layer 5 can be set according to actual usage requirements, and will not be elaborated further here.

[0093] The structure of the release layer in the embodiment of the invention can ensure appropriate adhesive strength while retaining a certain degree of adhesiveness, so that the metal foil will not delaminate during the hot pressing process.

[0094] In a preferred embodiment, the carrier layer 4 and / or the release layer 5 of the metal foil are filled with a heat-absorbing medium. By adding the heat-absorbing medium, when the metal foil is hot-pressed onto the circuit board substrate or hot-pressed together with the negative electrode active material as a negative electrode material in a new energy battery, the heat-absorbing medium can absorb heat, reducing the heat on the bonding surface of the conductive layer 3, and further reducing the occurrence of blistering, wrinkling, cracking, etc. during the bonding of the metal foil.

[0095] Preferably, the heat-absorbing medium is filler particles.

[0096] See Figures 6 to 8 This is a schematic diagram of the structure of the fifth to seventh types of metal foil provided in the embodiments of the present invention. In the metal foil, the filler particles are filled in three ways: one is to fill only the carrier layer 4 with the first filler particle 31, as detailed in [reference needed]. Figure 6 Secondly, the second filler particles 41 are filled only in the peeling layer 5, as detailed in [reference needed]. Figure 7 Third, the carrier layer 4 is filled with first filler particles 31, and the release layer 5 is filled with second filler particles 41. For details, please refer to [link to relevant documentation]. Figure 8.

[0097] Understandably, Figures 6 to 8 The shape of the filler particles described herein is merely exemplary. Due to differences in processing methods and parameters, the filler particles may also be in other shapes such as clusters, ice-like structures, stalactite-like structures, or dendritic structures. Furthermore, the heat-absorbing medium in the embodiments of the present invention is not limited to filler particles, nor is it limited to the shapes shown in the figures and described above. Any medium that fills the carrier layer or the release layer and has a heat-absorbing effect is within the protection scope of the present invention.

[0098] For a preferred embodiment, see Figure 9 This is a schematic diagram of the structure of the eighth type of metal foil provided in this embodiment of the invention. The metal foil includes a conductive layer 3, a carrier layer 4, and a release layer 5, and also includes an adhesive layer 6, which is disposed between the carrier layer 4 and the release layer 5. That is, the metal foil includes a carrier layer 4, an adhesive layer 6, a release layer 5, and a conductive layer 3 stacked sequentially, and the side of the conductive layer 3 away from the release layer 5 is the first surface 1, and the side of the conductive layer 3 close to the release layer 5 is the second surface 2.

[0099] In this embodiment of the invention, an adhesive layer 6 is added between the carrier layer 4 and the release layer 5 to improve the adhesion between them. During peeling, the two layers will not separate, and the increased peeling force effectively improves the peeling effect. Simultaneously, the presence of the adhesive layer 6 and the release layer 5 covers the uneven surface of the carrier layer 4, making the conductive layer 3 formed on the other side of the release layer 5 smoother, more uniform, and denser, reducing pinholes and facilitating subsequent circuit fabrication.

[0100] Preferably, the adhesive layer can be a metallic adhesive layer or a non-metallic adhesive layer. When it is a metallic adhesive layer, the metallic adhesive layer is made of any one or more materials selected from copper, zinc, nickel, iron, and manganese; or, the metallic adhesive layer is made of one of copper or zinc and one of nickel, iron, and manganese. When it is a non-metallic adhesive layer, its material is selected from at least one of polystyrene-based, vinyl acetate-based, polyester-based, polyethylene-based, polyamide-based, rubber-based or acrylate-based thermoplastic resins, phenolic resins, epoxy resins, thermoplastic polyimides, urethane-based, melamine-based or alkyd thermosetting resins, BT resins, and ABF resins.

[0101] For a preferred embodiment, see Figure 10This is a schematic diagram of the structure of a ninth type of metal foil provided in an embodiment of the present invention. The metal foil includes a conductive layer 3, a carrier layer 4, and a release layer 5, and also includes a first anti-oxidation layer 7, which is disposed on the second surface 2 of the conductive layer 3. That is, the metal foil includes a carrier layer 4, a release layer 5, a first anti-oxidation layer 7, and a conductive layer 3 stacked sequentially, and the side of the conductive layer 3 away from the release layer 5 is the first surface 1, and the side of the conductive layer 3 close to the release layer 5 is the second surface 2.

[0102] In this embodiment of the invention, a first anti-oxidation layer 7 is provided between the release layer 5 and the conductive layer 3. This improves the anti-oxidation performance of the conductive layer 3, prevents it from oxidizing and forming an oxide film that would affect its conductivity and thermal conductivity, and reduces the number of pinholes on the metal foil surface, ensuring the integrity of the etched circuitry after subsequent bonding to the circuit board substrate. Furthermore, since the adhesion between the first anti-oxidation layer 7 and the release layer 5 is relatively weak, it also improves the release effect.

[0103] Optionally, the first anti-oxidation layer is made of at least one of metals such as nickel, copper, chromium, and zinc, and / or an alloy including at least one of them. Exemplarily, the first anti-oxidation layer 7 is formed on the surface of the conductive layer 3 by processes including chemical plating, chemical micro-electroplating, etc.

[0104] For a preferred embodiment, see Figure 11 This is a schematic diagram of the tenth type of metal foil provided in this embodiment of the invention. The metal foil includes a conductive layer 3, a carrier layer 4, a release layer 5, and a first anti-oxidation layer 7, and also includes a second anti-oxidation layer 8, which is disposed on the side of the conductive layer 3 away from the release layer 5. That is, the metal foil includes a carrier layer 4, a release layer 5, a first anti-oxidation layer 7, a conductive layer 3, and a second anti-oxidation layer 8 stacked sequentially, and the side of the conductive layer 3 away from the release layer 5 is the first surface 1, and the side of the conductive layer 3 close to the release layer 5 is the second surface 2.

[0105] In this embodiment of the invention, a second anti-oxidation layer 8 is added to the first surface 1 of the conductive layer 3, which can effectively protect the anti-oxidation properties of the bonding surface between the conductive layer 3 and the circuit board substrate, and by selecting a suitable material, the bonding performance between the conductive layer 3 and the substrate can be improved synergistically.

[0106] Optionally, the second anti-oxidation layer is made of at least one of metals such as nickel, copper, chromium, and zinc, and / or an alloy of at least one of them. Exemplarily, the second anti-oxidation layer 8 is formed on the first surface 1 of the conductive layer 3 by processes including chemical plating, chemical micro-electroplating, etc.

[0107] For a preferred embodiment, see Figure 12This is a schematic diagram of the eleventh type of metal foil provided in this embodiment of the invention. The metal foil includes a conductive layer 3, a carrier layer 4, and a release layer 5, and also includes a resin layer 9, which is disposed on the first surface 1 of the conductive layer 3. That is, the metal foil includes the carrier layer 4, the release layer 5, the conductive layer 3, and the resin layer 9 stacked sequentially, and the side of the conductive layer 3 away from the release layer 5 is the first surface 1, and the side of the conductive layer 3 close to the release layer 5 is the second surface 2.

[0108] In this embodiment of the invention, a resin layer 9 is added to the first surface 1 of the conductive layer 3, that is, a resin layer 9 is provided on the surface where the conductive layer 3 is bonded to the circuit board substrate, which can achieve functions such as anti-oxidation, moisture-proof, and waterproof, and can also improve the bonding performance with the substrate.

[0109] The resin layer 9 is made of at least one of thermoplastic resin, thermosetting resin, BT resin, and ABF value, wherein the thermoplastic resin includes polystyrene-based, vinyl acetate-based, polyester-based, polyethylene-based, polyamide-based, rubber-based, or acrylate-based thermoplastic resins; the thermosetting resin includes phenolic, epoxy, thermoplastic polyimide, urethane-based, melamine-based, or alkyd-based thermosetting resins.

[0110] It should be noted that the structure of the metal foil provided in the embodiments of the present invention is not limited to the multi-layer structure of the above embodiments. In practical applications, other material layers and additional structures can be added as needed, which do not constitute a limitation of the present invention.

[0111] Using the technical means of this invention, the metal foil adopts a multi-layer structure. By optimizing the functional relationship between the water droplet angle Y and the root mean square roughness Rq of the second surface (the side opposite to the roughened surface of the metal foil), the water droplet angle and roughness of the second surface are both within an optimal range. The second surface of the metal foil has excellent hydrophilicity. When the metal foil is applied in the field of printed circuit boards, it needs to be bonded to a dry film for circuit etching in subsequent processes. The greater the hydrophilicity of the second surface 2 of the metal foil, the stronger the bonding strength with the hydrophilic dry film. This effectively prevents the etching solution from seeping into the gaps due to poor bonding between the metal foil surface and the dry film, resulting in etching in places that should not be etched. Therefore, the protection of the circuit is better during the circuit etching process, avoiding the occurrence of defective etching and ensuring the etching yield of the circuit. At the same time, during the etching process, the higher the hydrophilicity of the second surface of the metal foil, the easier it is for the etching solution to spread, and the more uniform the reaction between the etching solution and the metal foil. Over-etching or incomplete etching will not occur, and the etching rate of the metal foil will be faster, improving production efficiency and reducing production costs. Moreover, when metal foil is used in new energy batteries, its excellent hydrophilic surface ensures good adhesion between the metal foil and the electrolytic material. This prevents the electrolytic material from falling off or separating and bubbling during battery operation, thus ensuring the battery's performance, safety, and operational stability.

[0112] Example 2

[0113] This invention provides a circuit board, which includes a circuit board substrate and a metal foil as described in any of the above embodiments; the metal foil includes a first surface 1, which is pressed together with the circuit board substrate.

[0114] It should be noted that the structure of the metal foil can refer to the structure of the metal foil described in any of the above embodiments, and will not be repeated here.

[0115] By employing the technical means of this invention, the functional relationship between the water droplet angle Y and the root mean square roughness Rq of the side of the metal foil opposite to the roughened surface is optimized. This controls the surface roughness and water droplet angle within a reasonably optimal range, giving it excellent hydrophilic properties. This makes it suitable for the fabrication of high-frequency, high-density circuit boards. In subsequent processes, a dry film is laminated for circuit etching. The greater the adhesion strength between the metal foil surface and the hydrophilic dry film, the better it can prevent the etching solution from seeping into gaps due to poor adhesion between the metal foil surface and the dry film. This provides better protection for the circuit during etching, avoids defective etching, and ensures a high etching yield. Simultaneously, during etching, the easier the etching solution spreads, the more uniform the reaction between the etching solution and the metal foil, and the faster the etching rate of the metal foil, improving production efficiency and reducing production costs. Moreover, when metal foil is used in new energy batteries, its excellent hydrophilic surface ensures good adhesion between the metal foil and the electrolytic material. This prevents the electrolytic material from falling off or separating and bubbling during battery operation, thus ensuring the battery's performance, safety, and operational stability.

[0116] Example 3

[0117] The present invention also provides a copper clad laminate, specifically a flexible copper clad laminate (FCCL), also known as a flexible copper clad laminate, wherein the flexible copper clad laminate includes the metal foil as described in any of the above embodiments.

[0118] It should be noted that the structure of the metal foil can refer to the structure of the metal foil described in any of the above embodiments, and will not be repeated here.

[0119] The flexible copper-clad laminate structure includes: a metal foil layer, an adhesive layer, and another metal foil layer, or includes: a metal foil layer and an adhesive layer. The adhesive layer material can be polyimide (PI), thermoplastic polyimide (TPI), resin, etc.

[0120] Compared to existing technologies, using metal foil with an improved carrier layer as the material for the above flexible copper clad laminate has the following advantages: By optimizing the functional relationship between the water droplet angle Y and the root mean square roughness Rq of the side of the metal foil opposite to the roughened surface, the surface roughness and water droplet angle are controlled within a reasonable and optimal range, giving it excellent hydrophilic properties. This ensures greater adhesion to the hydrophilic adhesive layer in subsequent applications, thereby improving the yield of the manufactured copper clad laminate products. In subsequent specific applications, the product performance is more stable and reliable, with less high-frequency signal transmission loss and reduced production costs.

[0121] In addition, the copper-clad laminate can also be resin-coated copper foil (RCC), which is mainly used for high-density circuits. In this case, the roughened surface of the metal foil is away from the side of the copper foil coated with resin.

[0122] Example 4

[0123] This invention also provides a semiconductor material, which includes the metal foil described in any of the above embodiments.

[0124] It should be noted that the structure of the metal foil can refer to the structure of the metal foil described in any of the above embodiments, and will not be repeated here.

[0125] By employing the technical means of this invention, and using the metal foil as a semiconductor material, the functional relationship between the water droplet angle Y and the root mean square roughness Rq of the side of the metal foil opposite to the roughened surface is optimized. This controls the surface roughness and water droplet angle within a reasonably preferred range, giving it excellent hydrophilic properties. This ensures the adhesion strength with hydrophilic materials in subsequent applications, improves the quality of the metal foil product, and makes it suitable for manufacturing semiconductor devices and integrated circuits. This improves the quality and processing efficiency of semiconductor devices and integrated circuits, and reduces the defect rate of semiconductor devices and integrated circuits.

[0126] Example 5

[0127] This invention also provides a negative electrode material for use in batteries, the negative electrode material comprising the metal foil described in any of the above embodiments.

[0128] It should be noted that the structure of the metal foil can refer to the structure of the metal foil described in any of the above embodiments, and will not be repeated here.

[0129] This invention also provides a battery, wherein the negative electrode material of the battery includes a metal foil as described in any of the above embodiments.

[0130] Compared to existing technologies, using the aforementioned metal foil as the negative electrode carrier or current collector in the above-mentioned batteries has the following advantages: By optimizing the functional relationship between the water droplet angle Y and the root mean square roughness Rq of the side of the metal foil opposite to the roughened surface, the surface roughness and water droplet angle are controlled within a reasonably optimal range, giving it excellent hydrophilic properties. This ensures the adhesion strength with hydrophilic materials in subsequent applications, improving the quality of the metal foil product. Simultaneously, due to its rough surface, the battery's negative electrode active material is tightly bonded to the metal foil, making it less prone to detachment during battery use. Under strong impacts or during battery charging and discharging, the metal foil material is less likely to break or deform, which is beneficial for improving the service life and safety of new energy batteries. Therefore, the aforementioned metal foil is very suitable for use as a negative electrode current collector and carrier material in new energy batteries, such as lithium-ion batteries and sodium-ion batteries.

[0131] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A metal foil, characterized in that, This includes a first surface and a second surface, which are roughened surfaces. The root mean square roughness Rq of the second surface and the water droplet angle Y of the second surface satisfy the following functional relationship: Rq > 0, 0 < Y < 90°, and the correlation coefficient R² of the functional relationship is 0.9735, and the unit of the root mean square roughness Rq is μm.

2. The metal foil as described in claim 1, characterized in that, The water droplet angle Y on the second surface is 5°~38°.

3. The metal foil as described in claim 1, characterized in that, The root mean square roughness Rq of the second surface is 0.26~0.34μm.

4. The metal foil as described in claim 1, characterized in that, The roughness Rz of the first surface is 1.5~1.95μm.

5. The metal foil as described in claim 2, characterized in that, The water droplet angle X on the first surface is greater than the water droplet angle Y on the second surface, and the water droplet angle X on the first surface is less than or equal to 6 times the water droplet angle Y on the second surface.

6. The metal foil as described in claim 1, characterized in that, The metal foil includes a conductive layer, one side of which is the first surface and the other side of which is the second surface.

7. The metal foil as described in claim 6, characterized in that, The conductive layer is made of at least one of the following metallic elements: copper, aluminum, zinc, nickel, silver, titanium, gold, chromium, and cobalt, and / or an alloy thereof.

8. The metal foil as described in claim 7, characterized in that, The thickness of the conductive layer is 1~6μm.

9. The metal foil as described in claim 7, characterized in that, The metal foil further includes a carrier layer disposed on the second surface of the conductive layer.

10. The metal foil as claimed in claim 9, characterized in that, The carrier layer is made of at least one of the following metallic elements: copper, aluminum, zinc, nickel, chromium, iron, silver, and gold, and the thickness of the carrier layer is 5 to 50 μm; or, the carrier layer is made of an organic thin film, and the thickness of the carrier layer is 10 to 100 μm.

11. The metal foil as claimed in claim 9, characterized in that, The metal foil further includes a release layer disposed between the carrier layer and the conductive layer.

12. The metal foil as claimed in claim 11, characterized in that, The material of the release layer is a metallic material, and the thickness of the release layer is 2~100nm; or, the material of the release layer is a non-metallic material, and the thickness of the release layer is less than or equal to 1μm.

13. A circuit board, characterized in that, It includes a circuit board substrate and a metal foil as described in any one of claims 1 to 12; the roughened surface of the metal foil is pressed against the circuit board substrate.

14. A copper-clad laminate, characterized in that, The copper-clad laminate comprises the metal foil as described in any one of claims 1 to 12.

15. A semiconductor material, characterized in that, The semiconductor material includes the metal foil as described in any one of claims 1 to 12.

16. A negative electrode material for use in batteries, characterized in that, The negative electrode material includes the metal foil as described in any one of claims 1 to 12.

17. A battery, characterized in that, The negative electrode material of the battery includes the metal foil as described in any one of claims 1 to 12.

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