Carrier of metal foil, metal foil and its application

Abstract

The present invention discloses a carrier for a metal foil, the metal foil and their applications. The carrier includes opposite first and second surfaces, the roughness Rz of the first surface is greater than the roughness Rz of the second surface, and the arithmetic mean roughness Ra of the second surface and the water contact angle Y of the second surface satisfy the following functional relationship: Y = -3894.7×Ra<supgt;2< / supgt; + 1266.6×Ra - 61.96, Ra > 0, 0 < Y < 90°, and the correlation coefficient R<supgt;2< / supgt> of the functional relationship is 1. By adopting the technical means of the present invention, by optimizing the relationship between the arithmetic mean roughness and the water contact angle of the inner surface of the carrier of the metal foil, the hydrophilicity of the inner surface of the carrier is effectively improved, and the quality of the metal foil product is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal foils, and particularly to a carrier for a metal foil, the metal foil and their applications. Background Art

[0002] With the increasing demand for miniaturization and high performance of electronic devices, the high-density installation of mounted components has been continuously developed, and metal foils are widely used in various electronic technology fields, such as printed circuit boards, battery negative electrode materials, chip packaging, etc.

[0003] In the prior art, a carrier is usually covered on the surface of a metal foil to realize the functions of carrying and protecting the conductive layer in the metal foil. This requires that the metal foil carrier not only needs to have good strength to support the extremely thin metal foil, but also requires that the physical properties and chemical properties of its two surfaces reach certain requirements to facilitate the transportation and protection of the extremely thin metal foil. Due to the different functions of different sides of the carrier of the metal foil in the processing technology and actual application scenarios, the specific requirements for the physical properties of different sides of the carrier are also different.

[0004] In the process of manufacturing a metal foil, a conductive layer is usually formed on at least one surface of the carrier by electroplating. Since the electroplating solution is hydrophilic, if the hydrophilicity of the surface of the carrier on the side where the conductive layer is plated is not high, it will cause the electroplating solution to spread unevenly, resulting in uneven deposition of the electroplated conductive layer, thereby increasing metal nodules and grain aggregates on the surface of the conductive layer, and causing local electroplating defects such as pinholes on the surface of the conductive layer. This will affect the thickness, surface roughness, adhesion performance and peel strength of the finished metal foil, resulting in a decrease in the yield rate of the metal foil. Moreover, the low hydrophilicity of this side surface of the carrier will also reduce the efficiency of the electroplating process and affect the production efficiency of the metal foil. Summary of the Invention

[0005] The purpose of the embodiments of the present invention is to provide a carrier for a metal foil, the metal foil and their applications. By optimizing the relationship between the arithmetic mean roughness and the water contact angle of the inner surface of the carrier of the metal foil, the hydrophilicity of the inner surface of the carrier is effectively improved, and the quality of the metal foil product is improved.

[0006] To achieve the above purpose, the embodiments of the present invention provide a carrier for a metal foil. The carrier includes opposite first and second surfaces. The roughness Rz of the first surface is greater than the roughness Rz of the second surface, and the arithmetic mean roughness Ra of the second surface and the water contact angle Y of the second surface satisfy the following functional relationship:

[0007] Y = -3894.7×Ra 2 +1266.6×Ra - 61.96, Ra > 0, 0 < Y < 90°, and the

[0008] The correlation coefficient R of the functional relationship 2 is 1.

[0009] As an improvement to the above solution, the water contact angle Y of the second surface is 22° to 35°.

[0010] As an improvement to the above solution, the arithmetic mean roughness Ra of the second surface is 0.06 to 0.265 μm.

[0011] As an improvement to the above solution, the roughness Rz of the second surface is 3.5 to 7 μm.

[0012] As an improvement to the above solution, the water contact angle X of the first surface is 1.6 to 5 times that of the water contact angle Y of the second surface.

[0013] As an improvement to the above solution, the root mean square roughness Rq of the first surface is 0.2 to 0.42 μm.

[0014] The embodiment of the present invention also provides a metal foil, which includes a conductive layer and a carrier of the metal foil as described in any one of the above. The first surface of the carrier is the side surface away from the conductive layer, and the second surface of the carrier is the side surface close to the conductive layer.

[0015] As an improvement to the above solution, the material of the carrier includes at least one of the following metal elements: copper, aluminum, zinc; or, the material of the carrier is an organic film.

[0016] As an improvement to the above solution, the surface of the conductive layer away from the carrier is a roughened surface, and the roughened surface has a number of roughened particles; and the roughness Rz of the roughened surface is less than or equal to 1.8 μm.

[0017] As an improvement to the above solution, the material of the conductive layer includes at least one metal element of copper, aluminum, zinc, nickel and silver and / or an alloy of at least one of them; and the thickness of the conductive layer is 1 to 5 μm.

[0018] As an improvement to the above solution, the metal foil further includes a release layer, and the release layer is provided between the carrier and the conductive layer. The material of the release layer is a metal material. At this time, the thickness of the release layer is 2 to 100 nm; or, the material of the release layer is a non-metal material. At this time, the thickness of the release layer is less than or equal to 1 μm.

[0019] As an improvement to the above solution, release layer elements remain on the second surface of the carrier.

[0020] As an improvement of the above solution, no stripping layer elements remain on the second surface of the carrier.

[0021] An embodiment of the present invention further provides a circuit board, including a circuit board substrate and the metal foil as described in any one of the above; one side of the conductive layer away from the carrier is press-fitted with the circuit board substrate.

[0022] An embodiment of the present invention further provides a copper-clad laminate, and the copper-clad laminate includes the metal foil as described in any one of the above.

[0023] An embodiment of the present invention further provides a semiconductor material, and the semiconductor material includes the metal foil as described in any one of the above.

[0024] An embodiment of the present invention further provides a negative electrode material applied to a battery, and the negative electrode material includes the metal foil as described in any one of the above.

[0025] An embodiment of the present invention further provides a battery, and the negative electrode material of the battery includes the metal foil as described in any one of the above.

[0026] Compared with the prior art, the carrier, the metal foil and their applications of the metal foil disclosed in the embodiments of the present invention. The carrier includes opposite first and second surfaces, the roughness Rz of the first surface is greater than the roughness Rz of the second surface, and the arithmetic mean roughness Ra of the second surface and the water contact angle Y of the second surface satisfy the following functional relationship: Y = -3894.7×Ra 2 +1266.6×Ra - 61.96, Ra > 0, 0 < Y < 90°, and the correlation coefficient R of the functional relationship 2 is 1. By adopting the technical means of the embodiments of the present invention, one side surface of the carrier of the metal foil has good hydrophilicity. When electroplating a conductive layer on this side surface of the carrier during actual application, this side surface can be in full contact with the hydrophilic electroplating solution, enabling the electroplating solution to spread more evenly, and the deposition of the electroplated conductive layer to be more uniform. Thereby, it effectively reduces the generation of metal nodules and grain aggregates on the surface of the conductive layer, reduces the occurrence of pinholes formed due to local electroplating deficiency on the surface of the conductive layer, improves the uniformity of electroplating and the uniformity of the thickness of the metal foil, effectively improves the yield rate of the metal foil, and at the same time improves the electroplating process efficiency and the production efficiency of the metal foil. At the same time, it ensures the quality stability of the extremely thin metal foil produced by this electroplating during the circuit processing in the circuit board technical field, and is not prone to problems such as open circuit, short circuit, and uneven circuit etching due to too large thickness variation; when applied to new energy batteries, the excellent surface hydrophilicity of the carrier ensures good adhesion between the metal foil and the electrolytic material, ensuring that during the operation of the battery, it is not easy for the electrolytic raw materials to fall off or separate and foam from the surface of the metal foil, ensuring the performance, safety and working stability of the battery. Brief Description of the Drawings

[0027] Figure 1 FIG. is a schematic structural view of a carrier for a metal foil provided by an embodiment of the present invention;

[0028] Figure 2 FIG. is a top-down electron microscope image of the second surface of the carrier of the metal foil in an embodiment of the present invention;

[0029] Figure 3 FIG. is a schematic structural view of a first metal foil provided by an embodiment of the present invention;

[0030] Figure 4 FIG. is a schematic structural view of a second metal foil provided by an embodiment of the present invention;

[0031] Figure 5 FIG. is a schematic structural view of a third metal foil provided by an embodiment of the present invention;

[0032] Figure 6 FIG. is a schematic structural view of a fourth metal foil provided by an embodiment of the present invention;

[0033] Figure 7 FIG. is a schematic structural view of a fifth metal foil provided by an embodiment of the present invention;

[0034] Figure 8 FIG. is a schematic structural view of a sixth metal foil provided by an embodiment of the present invention;

[0035] Figure 9 FIG. is a schematic structural view of a seventh metal foil provided by an embodiment of the present invention;

[0036] Figure 10 FIG. is a schematic structural view of an eighth metal foil provided by an embodiment of the present invention;

[0037] Figure 11 FIG. is a schematic structural view of a ninth metal foil provided by an embodiment of the present invention;

[0038] Figure 12 FIG. is a schematic structural view of a tenth metal foil provided by an embodiment of the present invention;

[0039] Wherein, 1. Carrier; 11. First surface; 12. Second surface; 13. First filler particle; 2. Conductive layer; 21. Roughened surface; 22. Roughened particle; 3. Release layer; 31. Second filler particle; 4. Adhesive layer; 5. First anti-oxidation layer; 6. Second anti-oxidation layer; 7. Resin layer. Detailed Description of the Invention

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] In the description of the specification and claims, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the embodiments of the present invention, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the embodiments of the present invention.

[0042] In addition, the terms "first", "second", etc. in the specification and claims are only used for the purpose of distinguishing the description of the same technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the technical features indicated. Nor does it necessarily describe the order or time sequence. The terms may be interchanged under appropriate circumstances. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature.

[0043] Example 1

[0044] See Figure 1 and Figure 2 , Figure 1 FIG. is a schematic structural diagram of a carrier for a metal foil provided by an embodiment of the present invention, Figure 2 FIG. is a top-down electron microscope image of the second surface of the carrier of the metal foil in the embodiment of the present invention. An embodiment of the present invention provides a carrier 1 for a metal foil. The carrier 1 includes a first surface 11 and a second surface 12 that are opposite to each other.

[0045] It should be noted that when the carrier 1 is applied to the application scenario of the metal foil, it is stacked with other material layers in the metal foil and is used to carry and protect the material layer so that the material layer is not damaged by external contact, collision, etc.

[0046] In an embodiment of the present invention, the first surface 11 of the carrier 1 is the surface on the side away from the metal foil, and the second surface 12 is the surface on the side close to the metal foil. That is, the carrier 1 is stacked with other material layers of the metal foil, such as a conductive layer, through the second surface 12. The first surface 11 and the second surface 12 of the carrier 1 have a certain roughness. Moreover, since the material layers contacted by the two side surfaces of the carrier 1 are different, their roughnesses are not the same. The roughness Rz of the first surface 11 of the carrier 1 is greater than the roughness Rz of the second surface 12.

[0047] As an alternative embodiment, a preset roughening treatment is performed on the first surface 11, while no specific roughening treatment is performed on the second surface 12, such that the roughness Rz of the first surface 11 is greater than the roughness Rz of the second surface 12. Moreover, the specific value of the roughness Rz of the first surface 11 is controlled through the preset roughening treatment process.

[0048] It should be noted that the roughness Rz is the sum of the average value of n maximum profile peak heights and the average value of n maximum 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.

[0049] It should be noted that the roughening treatment process for the surface of the carrier 1 includes: it can be achieved by setting the surface of the carrier 1 as an undulating non-planar surface, or by setting a number of micro-concavities and micro-protrusions on the surface of the carrier 1, or by setting a number of raised roughening particles on the surface of the carrier 1. Of course, it can also be a combination of at least two of the above three implementation methods, which does not affect the beneficial effects achieved by the present invention.

[0050] Moreover, the micro-concavities and micro-protrusions or the raised roughening particles provided on the surface of the carrier 1 can be in the shape of clusters, icicles, stalactites, dendrites or other shapes. Of course, the shapes of the micro-concavities and micro-protrusions or the raised roughening particles are not limited to the above shapes, as long as they have the function of providing the surface roughness of the carrier, they are within the protection scope of the present invention. Moreover, in specific implementation, the carrier 1 can be first formed, and then micro-concavities and micro-protrusions or raised roughening particles can be provided on the carrier 1 through other processes; of course, the carrier 1 can also be an integral structure formed by a one-step forming process. Moreover, the material of the micro-concavities and micro-protrusions or the raised roughening particles can be the same as or different from the material of the carrier of the metal foil, which is not limited herein.

[0051] By adopting the technical means of the embodiments of the present invention, the first surface 11 of the carrier has a relatively large roughness, so that during the transmission of the metal foil, due to the existence of the rough surface of the carrier, the metal foil has better adhesion, and can avoid the problem that the metal foil is very likely to slip and skew during the conveying process due to the very smooth surface of the conveying roller, which in turn leads to wrinkles in the winding, and further leads to the scrapping of the entire roll of copper foil. It can also avoid the influence on the product stability under the condition of high-temperature baking during the subsequent application process, and reduce the occurrence of problems such as blistering and cracking. The second surface 12 of the carrier is relatively smooth, so that the metal foil replicates the rough morphology of the second surface of the carrier, and generates a more appropriate roughness, which is not too large, thus avoiding the problem of excessive transmission loss during the application of the metal foil.

[0052] Further, the arithmetic mean roughness Ra of the second surface 12 and the water contact angle Y of the second surface satisfy the following functional relationship:

[0053] Y = -3894.7×Ra 2 +1266.6×Ra - 61.96, Ra > 0, 0 < Y < 90°, and the

[0054] correlation coefficient R of the functional relationship 2 is 1.

[0055] It should be noted that the arithmetic mean roughness Ra is specifically the arithmetic mean of the absolute values of the profile ordinate values Z(x) within a sampling length, and the ordinate value Z(x) refers to the distance from each point on the profile to the profile center line. The arithmetic mean roughness Ra is used to evaluate the arithmetic mean deviation of the surface profile, and it can fully reflect the characteristics of the surface microgeometry in terms of height.

[0056] In practical applications, the hydrophilic property required by the second surface 12 of the carrier 1 is related to the size of the water contact angle Y and the roughness of this surface. Generally, the smaller the water contact angle Y, the stronger the hydrophilicity; the larger the water contact angle Y, the weaker the hydrophilicity; the smaller the roughness, the stronger the hydrophilicity; the larger the roughness, the weaker the hydrophilicity. In the embodiments of the present invention, by fitting the functional relationship between the arithmetic mean roughness Ra and the water contact angle Y, the arithmetic mean roughness Ra of the second surface 12 of the carrier 1 and the water contact angle Y of this surface have a certain functional correlation. When the water contact angle Y and the arithmetic mean roughness Ra of the second surface 12 of the carrier 1 simultaneously satisfy the above functional relationship, it can make the second surface 12 have a reasonable roughness range and a reasonable range value of the water contact angle at the same time, so that the hydrophilic property presented by the second surface 12 is better, meeting the hydrophilicity requirements for the inner surface of the carrier. And, the correlation coefficient R of the functional relationship 2is 1, indicating a good fitting regression effect and a strong linear relationship between the arithmetic mean roughness Ra and the water contact angle Y.

[0057] By adopting the technical means of the embodiment of the present invention, one side surface of the carrier of the metal foil has good hydrophilicity. When electroplating a conductive layer on this side surface of the carrier in actual application, this side surface can be in full contact with the hydrophilic electroplating solution, enabling the electroplating solution to spread more evenly, and the deposition of the electroplated conductive layer to be more uniform. Thereby, it effectively reduces the generation of metal nodules and grain aggregates on the surface of the conductive layer, reduces the occurrence of pinholes formed due to local electroplating deficiency on the surface of the conductive layer, improves the uniformity of electroplating and the uniformity of the metal foil thickness, effectively improves the yield rate of the metal foil, and at the same time improves the electroplating process efficiency and the production efficiency of the metal foil. Meanwhile, it ensures that when the extremely thin metal foil produced by this electroplating is applied to the field of circuit board technology, the quality is stable during the circuit processing, and it is not easy to generate problems such as open circuit, short circuit, and uneven circuit etching due to too large thickness variation; when applied to new energy batteries, the excellent surface hydrophilicity of the carrier ensures good adhesion between the metal foil and the electrolytic material, ensuring that during the operation of the battery, it is not easy for the electrolytic raw material to fall off or separate and form bubbles from the surface of the metal foil, ensuring the performance, safety, and working stability of the battery.

[0058] As a preferred embodiment, the water contact angle Y of the second surface is 22° - 35°.

[0059] In the embodiment of the present invention, based on the functional relationship of Y = -3894.7×Ra 2 +1266.6×Ra - 61.96 between the water contact angle Y and the arithmetic mean roughness Ra of the second surface 12 of the carrier, the numerical range of the water contact angle Y of the second surface 12 is further optimized. The water contact angle of the second surface 12 is between 22° and 35°, for example, it can be 22°, 23°, 24°, 24.5°, 25°, 25.5°, 26°, 26.5°, 27°, 27.5°, 28°, 28.5°, 29°, 29.5°, 30°, 30.5°, 31°, 32°, 33°, 34° or 35°, etc. Of course, the specific value of the water contact angle Y of the second surface 12 can be set according to actual usage requirements and will not be elaborated further here.

[0060] By adopting the technical means of the embodiments of the present invention, the water contact angle Y of the second surface 12 is within a reasonable range. Moreover, based on the above functional relationship, the roughness of the second surface 12 is also within a reasonable range, endowing the second surface 12 with excellent hydrophilicity. When electroplating a conductive layer on the second surface 12, the electroplating solution can spread more evenly, and the deposition of the electroplated conductive layer is also more uniform. Thus, the generation of metal nodules and grain aggregates on the surface of the conductive layer is effectively reduced, and the formation of pinholes on the surface of the conductive layer is reduced. The electroplating uniformity and the uniformity of the metal foil thickness are improved, effectively increasing the yield rate of the metal foil. At the same time, the electroplating process efficiency is increased, and the production efficiency of the metal foil is improved.

[0061] As a preferred embodiment, the arithmetic mean roughness Ra of the second surface is 0.06 - 0.265 μm.

[0062] In the embodiments of the present invention, based on the functional relationship that the water contact angle Y and the arithmetic mean roughness Ra of the second surface 12 of the carrier satisfy Y = -3894.7×Ra 2 +1266.6×Ra - 61.96, the numerical range of the arithmetic mean roughness Ra of the second surface 12 is further optimized. The arithmetic mean roughness Ra of the second surface 12 is between 0.06 - 0.265 μm, and can be, for example, 0.06 μm, 0.08 μm, 0.09 μm, 0.1 μm, 0.11 μm, 0.12 μm, 0.13 μm, 0.14 μm, 0.15 μm, 0.16 μm, 0.17 μm, 0.18 μm, 0.19 μm, 0.2 μm, 0.21 μm, 0.23 μm, 0.25 μm or 0.265 μm, etc. Of course, the specific value of the arithmetic mean roughness Ra of the second surface 12 can be set according to actual usage requirements and will not be elaborated further here.

[0063] By adopting the technical means of the embodiments of the present invention, the roughness of the second surface 12 is within a reasonable range, and this roughness range is relatively small, making the second surface 12 relatively smooth. During the production process of the metal foil, the conductive layer replicates the rough morphology of the second surface of the carrier, generating a more suitable roughness, thereby avoiding the problem of excessive transmission loss during the application of the metal foil. Moreover, based on the above functional relationship, the contact angle Y of water droplets on the second surface 12 is also within a reasonable range, endowing the second surface 12 with excellent hydrophilicity. When electroplating the conductive layer on the second surface 12, the electroplating solution can spread more evenly, and the deposition of the electroplated conductive layer is also more uniform. As a result, the generation of metal nodules and grain aggregates on the surface of the conductive layer is effectively reduced, and the occurrence of pinholes on the surface of the conductive layer is reduced, improving the uniformity of electroplating and the uniformity of the thickness of the metal foil, effectively increasing the yield rate of the metal foil, while also improving the efficiency of the electroplating process and the production efficiency of the metal foil.

[0064] As a preferred embodiment, the roughness Rz of the second surface is 3.5 - 7 μm.

[0065] In the embodiments of the present invention, on the basis that the contact angle Y of water droplets and the arithmetic mean roughness Ra of the second surface 12 of the carrier satisfy the above functional relationship, the numerical range of the roughness Rz of the second surface 12 is further optimized. The roughness Rz of the roughened surface is between 3.5 - 7 μm. For example, it can be 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm or 7 μm, etc. Of course, it can also be set to other values within 3.5 - 7 μm according to the actual situation, which will not be elaborated here.

[0066] By adopting the technical means of the embodiments of the present invention, the rough characteristics of the second surface 12 are characterized by the combination of the arithmetic mean roughness Ra and the roughness Rz. This not only fully reflects the characteristics of the microscopic geometric shape of the second surface in terms of height but also fully reflects the peak height of the profile of the second surface, making the roughness of the second surface more reasonable, improving the hydrophilic performance of the second surface, and making the surface morphology, roughness and other properties of the conductive layer electroplated on this surface more excellent, thus improving the quality of the metal foil.

[0067] As a preferred embodiment, the contact angle X of water droplets on the first surface is 1.6 - 5 times that of the contact angle Y of water droplets on the second surface.

[0068] In an embodiment of the present invention, the water contact angle X of the first surface 11 of the carrier is greater than the water contact angle Y of the second surface 12, and the water contact angle X of the first surface 11 is 1.6 to 5 times that of the water contact angle Y of the second surface 12. When the water contact angle Y of the second surface 12 is within the range of 22° to 35°, the water contact angle X of the first surface 11 is delimited according to this ratio, so that the first surface 11 of the carrier has a certain hydrophobicity. Since the first surface of the carrier is the outer surface in practical applications, the hydrophobic surface can well overcome various adverse problems caused by the adsorption of pollutants such as moisture in the air on the outer surface of the carrier, such as the surface moisture and air oxidation of the carrier. When the carrier is used as a carrier for metal foil, it can avoid the adverse effects on the extremely thin metal foil carried due to the oxidation of the carrier itself. For example, during high-temperature lamination, due to the high hardness of the oxidation points, surface unevenness problems such as pits and protrusions may occur on the surface of the laminated extremely thin metal foil, and even cause the carrier to crack from the oxidation points, resulting in wrinkles and bubbles of the extremely thin metal foil. At the same time, it also avoids the adhesion of the oxidation points to the surface of the press plate during the lamination process, which pollutes the press and further affects the subsequent lamination process. It can effectively play the role of carrying and protecting the metal foil, simplify the environmental requirements for the transportation and storage of the metal foil, and reduce the cleaning process before the application of the metal foil. At the same time, when the carrier is recycled, the surface in contact with the outside air has good hydrophobicity, which can further ensure that the subsequent reuse process is simpler and more convenient.

[0069] As a preferred embodiment, the root mean square roughness Rq of the first surface is 0.2 to 0.42 μm.

[0070] It should be noted that the root mean square roughness Rq is specifically the root mean square value of the profile ordinate value Z(x) within a sampling length, and the ordinate value Z(x) refers to the distance from each point on the profile to the profile center line, which can fully reflect the characteristics of the surface microgeometry in terms of height.

[0071] In an embodiment of the present invention, the root mean square roughness Rq of the first surface 11 is further optimized. The root mean square roughness Rq of the first surface is between 0.2 and 0.42 μm. For example, it can be 0.2 μm, 0.25 μm, 0.3 μm, 0.32 μm, 0.34 μm, 0.35 μm, 0.36 μm, 0.37 μm, 0.38 μm, 0.39 μm, 0.4 μm or 0.42 μm. Of course, the specific value of the root mean square roughness Rq of the first surface 11 can be set according to actual usage requirements, and no more details will be elaborated here.

[0072] By adopting the technical means of the embodiments of the present invention, a reasonable roughness is provided on the first surface, improving the good adhesion strength between the metal foil and the surface of the transmission roller during the transmission process, and effectively meeting the requirements of the appropriate peeling strength between the metal foil and the carrier during the application process.

[0073] Example 2

[0074] As a preferred embodiment, refer to Figure 3 , which is a schematic structural diagram of the first metal foil provided by the embodiments of the present invention. The metal foil includes a carrier 1 and a conductive layer 2. Among them, the carrier 1 is the carrier 1 provided by any of the above embodiments, that is, the carrier 1 includes opposite first surface 11 and second surface 12, and the roughness Rz of the first surface is greater than the roughness Rz of the second surface; the arithmetic mean roughness Ra of the second surface and the water contact angle Y of the second surface satisfy the following functional relationship: Y = -3894.7×Ra 2 +1266.6×Ra - 61.96, Ra > 0, 0 < Y < 90°. And, the first surface 11 of the carrier 1 is the side surface away from the conductive layer 2, and the second surface 12 of the carrier 1 is the side surface close to the conductive layer 2.

[0075] Preferably, the conductive layer 2 is formed on the second surface 12 of the above carrier 1 by means of vacuum sputtering, evaporation plating, electroplating or the like.

[0076] Preferably, the material of the carrier includes at least one of the following metal elements: copper, aluminum, zinc; or, the material of the carrier is an organic film.

[0077] In the embodiments of the present invention, the metal foil is a multi-layer structure, including a conductive layer 2 and a carrier 1 stacked in sequence. The carrier 1 is used to carry and protect the conductive layer 2 so that the conductive layer 2 is not damaged by external contact or collision, etc. After the metal foil is hot-pressed with the circuit board, the carrier 1 needs to be peeled off.

[0078] The carrier 1 is separated from the carrier 1 in a peelable removal manner or a non-peelable removal manner. When the carrier 1 is removed in a non-peelable removal manner, the non-peeling methods are such as: laser etching, chemical etching, grinding, plasma removal, etc. When the carrier 1 is removed by peeling, the peeling methods are such as: manually peeling off directly, or peeling off with the aid of mechanical equipment.

[0079] Preferably, the conductive layer 2 is an extremely thin conductive layer, and the surface of the conductive layer 2 away from the carrier 1 is a roughened surface 21 with a certain roughness. It should be noted that the roughness of the roughened surface of the conductive layer 2 can be achieved by setting the surface of the conductive layer 2 as an uneven surface with undulations, or by setting a number of minute concavities and convexities on the surface of the conductive layer 2, or by setting a number of raised roughening particles on the surface of the conductive layer 2. Of course, it can also be a combination of at least two of the above three implementation methods, which does not affect the beneficial effects achieved by the present invention.

[0080] As an alternative embodiment, refer to Figure 4 , which is a schematic structural diagram of the second metal foil provided by the embodiment of the present invention. The roughened surface 21 has a number of roughening particles 22; and the roughness Rz of the roughened surface 21 is less than or equal to 1.8 μm, preferably 1 - 1.6 μm.

[0081] Adopting this preferred roughness can ensure good substrate adhesion strength while reducing the occurrence of the skin effect and reducing the loss of line transmission signals.

[0082] Preferably, the material of the conductive layer includes at least one metal element among copper, aluminum, zinc, nickel, silver, and gold and / or an alloy of at least one of them; and the thickness of the conductive layer is 1 - 5 μm, preferably 1.5 - 4.5 μm.

[0083] Adopting this ultra-thin conductive layer with a preferred thickness broadens its application, making it convenient to be applied in special applications such as fine circuits, and it can also be applied to ordinary circuits, reducing costs, reducing the weight for smart devices, and better meeting the design and application requirements of current smart devices.

[0084] In the embodiment of the present invention, in practical applications of the metal foil, for example, when applied in the field of circuit boards, the conductive layer 2 is thermally pressed and bonded to the substrate of the circuit board. And for example, when applied in the field of batteries, the metal foil serves as the negative electrode material of the battery, and the conductive layer 2 is thermally pressed and bonded to the negative electrode active material in the negative electrode material. The surface of the conductive layer 2 for bonding to materials such as the substrate of the circuit board or the negative electrode active material is set as the roughened surface 21, thereby increasing the adhesiveness of the conductive layer 2 and reducing the occurrence of problems such as blistering, wrinkling, and cracking during bonding.

[0085] The conductive layer 2 is made of a metal with good conductivity and low resistivity. The constituent materials of the conductive layer 2 include single metals and / or alloys; among them, the single metal is made of any one of copper, aluminum, zinc, nickel, silver, and gold, and the alloy is made of any two or more of copper, aluminum, zinc, nickel, silver, and gold, or can also be made by mixing any two or more of copper, aluminum, zinc, nickel, silver, and gold with other materials.

[0086] In the specific implementation process, the conductive layer 2 of the metal foil can be formed first, and then the roughened particles 22 can be formed on one surface of the conductive layer 2 through other processes. Of course, the conductive layer 2 of the metal foil and the roughened particles 22 can also be an integral structure formed by a one-step forming process. It should be noted that the material of the roughened particles 22 can be the same as that of the conductive layer 2, or partially the same or different, and no limitation is made here.

[0087] Preferably, referring to Figure 5 , it is a schematic structural diagram of the third metal foil provided by the embodiment of the present invention. The metal foil includes a carrier 1 and a conductive layer 2, and further includes a release layer 3. The release layer 3 is disposed between the carrier 1 and the conductive layer 2, that is, the metal foil includes the carrier 1, the release layer 3, and the conductive layer 2 stacked in sequence. The side of the carrier 1 away from the release layer 3 is the first surface 11, the side of the carrier 1 close to the release layer 3 is the second surface 12, and the surface of the conductive layer 2 away from the release layer 3 is the roughened surface 21.

[0088] In the embodiment of the present invention, when the carrier 1 is removed by peeling, the peeling method is: removing it by peeling the release layer 3, that is, separating the carrier 1 from the conductive layer 2 by the peeling of the release layer 3.

[0089] At the same time, due to the existence of the release layer, it can block the metal migration between the conductive layer 2 and the carrier 1. Moreover, the release layer 3 can cover or fill the uneven surface of the carrier 1, making the conductive layer 2 formed on the other surface of the release layer 3 more flat, uniform, and dense, reducing the occurrence of pinholes, and thus being beneficial to the subsequent circuit manufacturing.

[0090] Preferably, the release layer 3 is made of a metallic material or a non-metallic material. The metallic materials include any one or more of zinc, nickel, cadmium, copper, molybdenum, titanium, and niobium; the non-metallic materials include oxygen, silicon, graphite, organic polymer materials, etc. When the release layer is a non-metallic material, it may be in the form of a release layer. The release layer includes a non-silicon release agent release layer, a silicone oil release layer, or a nitrogen release layer. Among them, 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 the above two release agents are used, the mass ratio of HDPE:PMA is preferably (1-5):7. In another embodiment, the release agent may include a fluorine release agent and a solvent; among them, the volume ratio of the fluorine release agent to the solvent is preferably (5-30):1. It can be understood that the types of the above solvents are not particularly limited, and conventional release agent solvents in the art can be selected, such as methyl ethyl ketone, which does not constitute a limitation to the present invention.

[0091] Preferably, when the material of the release layer 3 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 3 can be set according to actual use requirements, and no more details will be described here.

[0092] Adopting the structural setting of the release layer in the embodiment of the invention can ensure appropriate adhesion strength. At the same time, it also retains a certain adhesion ability, so that the metal foil will not delaminate during the hot pressing process.

[0093] As a preferred embodiment, in the metal foil, a heat-absorbing medium is filled in the carrier 1 and / or the release layer 3. By adding the heat-absorbing medium, when the metal foil is hot-pressed onto the circuit board substrate or hot-pressed and bonded as the negative electrode material of a new energy battery with the negative electrode active material, the heat-absorbing medium can absorb heat, reduce the heat of the bonding surface of the conductive layer 2, and further reduce the occurrence of blistering, wrinkling, cracking, etc. during the bonding of the metal foil.

[0094] Preferably, the heat-absorbing medium is filler particles.

[0095] See Figures 6 to 8 , which is a schematic structural diagram of the fourth to sixth metal foils provided by the embodiment of the present invention. In the metal foil, there are three filling methods for the filler particles: one is to fill only the first filler particles 13 in the carrier 1, and specifically, reference can be made to Figure 6 ; the second is to fill only the second filler particles 31 in the release layer 3, and specifically, reference can be made to Figure 7 ; the third is to fill the first filler particles 13 in the carrier 1 and fill the second filler particles 31 in the release layer 3, and specifically, reference can be made toFigure 8 。

[0096] Understandably, Figures 6 to 8 the shape of the filler particles in [[]] is merely exemplary. Due to differences in process means and parameters, the filler particles can also be in other shapes such as cluster shape, icicle shape, stalactite shape, dendritic shape, etc. In addition, the medium for heat absorption in the embodiments of the present invention is not limited to filler particles, nor is it limited by the illustration and the above shapes. As long as it is a medium filled in the carrier or the release layer and has a heat absorption effect, it is within the protection scope of the present invention.

[0097] As a preferred embodiment, referring to Figure 9 , it is a schematic structural diagram of the seventh metal foil provided by the embodiment of the present invention. The metal foil includes a conductive layer 2, a carrier 1, and a release layer 3, and further includes an adhesive layer 4. The adhesive layer 4 is disposed between the carrier 1 and the release layer 3. That is, the metal foil includes the carrier 1, the adhesive layer 4, the release layer 3, and the conductive layer 2 which are sequentially stacked, and the surface of the conductive layer 2 away from the release layer 3 is the roughened surface 1.

[0098] By adopting the technical means of the embodiment of the present invention, an adhesive layer 4 is added between the carrier 1 and the release layer 3, the adhesion between the carrier 1 and the release layer 3 is improved, and the two will not separate during peeling, and the peeling force is increased, which can effectively improve the peeling effect. At the same time, due to the presence of the adhesive layer 4 and the release layer 3, the uneven surface of the carrier 1 can be covered, so that the conductive layer 2 formed on the other side of the release layer 3 is more flat, uniform and dense, reducing the occurrence of pinholes, which is beneficial to the subsequent circuit production.

[0099] Preferably, the adhesive layer can be a metal adhesive layer or a non-metal adhesive layer. When it is a metal adhesive layer, the metal adhesive layer is made of any one or more of copper, zinc, nickel, iron and manganese; or, the metal adhesive layer is made of one of copper or zinc and one of nickel, iron and manganese. When it is a non-metal adhesive layer, its material is selected from at least one of thermoplastic resins such as polystyrene series, vinyl acetate series, polyester series, polyethylene series, polyamide series, rubber series or acrylate series, thermosetting resins such as phenolic series, epoxy series, thermoplastic polyimide, urethane series, melamine series or alkyd series, BT resin, and ABF resin.

[0100] As a preferred embodiment, referring to Figure 10 , it is a schematic structural diagram of the eighth metal foil provided by the embodiment of the present invention. The metal foil further includes a first anti-oxidation layer 5, and the first anti-oxidation layer 5 is disposed on the surface of the conductive layer 2 close to the release layer 3. That is, the metal foil includes the carrier 1, the release layer 3, the first anti-oxidation layer 5, and the conductive layer 2 which are sequentially stacked.

[0101] In the embodiment of the present invention, a first anti-oxidation layer 5 is provided between the release layer 3 and the conductive layer 2, which can improve the anti-oxidation performance of the conductive layer 2, prevent the formation of an oxide film due to oxidation, affect the conductive and heat-conductive effects, and at the same time reduce the number of pinholes on the surface of the metal foil, ensuring the integrity of the etching circuit conduction after subsequent bonding to the circuit board substrate. Moreover, since the adhesion between the first anti-oxidation layer 5 and the release layer 3 is weak, the release effect can also be improved.

[0102] Optionally, the first anti-oxidation layer 5 is made of at least one of metals such as nickel, copper, chromium, zinc, etc. and / or an alloy including at least one of them. Exemplarily, the first anti-oxidation layer 5 is formed on the surface of the conductive layer 2 through processes including electroless plating, chemical microelectroplating, etc.

[0103] As a preferred embodiment, referring to Figure 11 , it is a schematic structural diagram of the ninth type of metal foil provided by the embodiment of the present invention. The metal foil further includes a second anti-oxidation layer 6, and the second anti-oxidation layer 6 is provided on the surface of the conductive layer 2 away from the release layer 3. That is, the metal foil includes a carrier 1, a release layer 3, a first anti-oxidation layer 5, a conductive layer 2, and a second anti-oxidation layer 6 which are sequentially stacked.

[0104] In the embodiment of the present invention, adding a second anti-oxidation layer 6 on the roughened surface 21 of the conductive layer 2 can effectively protect the anti-oxidation property of the bonding surface between the conductive layer 2 and the circuit board substrate, and by selecting a suitable material, the bonding performance between the conductive layer 2 and the substrate can be synergistically improved.

[0105] Optionally, the second anti-oxidation layer 6 is made of at least one of metals such as nickel, copper, chromium, zinc, etc. and / or an alloy of at least one of them. Exemplarily, the second anti-oxidation layer 6 is formed on the roughened surface 21 of the conductive layer 2 through processes including electroless plating, chemical microelectroplating, etc.

[0106] As a preferred embodiment, referring to Figure 12 , it is a schematic structural diagram of the tenth type of metal foil provided by the embodiment of the present invention. The metal foil further includes a resin layer 7, and the resin layer 7 is provided on the surface of the conductive layer 2 away from the release layer 3. That is, the metal foil includes a carrier 1, a release layer 3, a conductive layer 2, and a resin layer 7 which are sequentially stacked.

[0107] In the embodiment of the present invention, adding a resin layer 7 on the roughened surface 21 of the conductive layer 2, that is, setting a resin layer 7 on the surface where the conductive layer 2 is bonded to the circuit board substrate, can not only achieve functions such as anti-oxidation, moisture-proof, and waterproof, but also improve the bonding performance with the substrate.

[0108] The resin layer 7 is made of at least one of thermoplastic resin, thermosetting resin, BT resin, and ABF resin. Among them, thermoplastic resins include polystyrene-based, vinyl acetate-based, polyester-based, polyethylene-based, polyamide-based, rubber-based, or acrylate-based thermoplastic resins; thermosetting resins include phenolic-based, epoxy-based, thermoplastic polyimide, urethane-based, melamine-based, or alkyd-based thermosetting resins.

[0109] 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 also be added according to requirements, which do not constitute a limitation to the present invention.

[0110] In the embodiments of the present invention, the test methods for the arithmetic mean roughness Ra and the water contact angle Y of the second surface of the carrier are specifically as follows:

[0111] Measurement method of arithmetic mean roughness Ra: Cut the sample into a size of 200mm×250mm. After pressing the roughened surface of the conductive layer onto the adhesive surface of the cover film, peel off the carrier, and use a contact roughness tester or a white light interferometer to measure the values of the arithmetic mean roughness Ra at different positions (at least 20 test points) on the second surface of the carrier, and calculate the average value respectively as the arithmetic mean roughness Ra and the root mean square roughness Rq of the first surface.

[0112] Test method for water contact angle Y: Cut the metal foil sample into a size of 100mm×150mm. After pressing the roughened surface of the conductive layer onto the adhesive surface of the cover film, peel off the carrier, and use a water contact angle test device to measure the water contact angle values at different positions (at least 20 test points) on the second surface of the carrier, and calculate the average value as the water contact angle Y of this surface.

[0113] Specific examples were used to test and compare the electroplating deposition rate, the number of pinholes per unit area, and the thickness uniformity of the ordinary metal foil and the metal foil with the structure of the embodiments of the present invention.

[0114] Among them, A represents the metal foil product of the embodiments of the present invention. A total of 3 metal foil samples, A1, A2, and A3, were randomly selected. B represents a commercially available ordinary metal foil product. Then, the test data of the water contact angle Y and the arithmetic mean roughness Ra of the second surface 12 of the carriers of the metal foil products A1, A2, A3 of the embodiments of the present invention and the commercially available ordinary metal foil product B are shown in Table 1:

[0115] Table 1

[0116] Metal foil product Contact angle (°) Arithmetic mean roughness Ra (μm) A1 0.016 0.06 A2 39.523 0.143 A3 40.942 0.167 B 84.36 0.36

[0117] The comparison results of the performance of the metal foil products A1, A2, and A3 in the embodiments of the present invention and the commercially available ordinary metal foil product B are shown in Table 2 as follows:

[0118] Table 2

[0119]

[0120]

[0121] It can be seen from this that compared with the ordinary metal foil sold on the market, the metal foil adopting the structure of the embodiment of the present invention optimizes the structure of the surface of the carrier in contact with the conductive layer, so that the electroplating deposition rate of the metal foil is higher than that of the ordinary metal foil, the number of pinholes per unit area of the metal foil is less, the thickness uniformity of the metal foil is better, and all performances are superior to those of ordinary commercially available products.

[0122] It should be noted that all the roughness parameters and water contact angles of the second surface 12 of the carrier measured in the embodiments of the present invention are the data of the carrier peeled from the finished metal foil. Therefore, the carrier includes (part of) the peeling layer.

[0123] By adopting the technical means of the embodiments of the present invention, the metal foil adopts a multi-layer structure. Among them, the carrier includes opposite first and second surfaces. By optimizing the relationship between the roughness Rz of the two opposite surfaces of the carrier, the roughness of the second surface and the water contact angle, the side surface can be fully contacted with the hydrophilic electroplating solution, so that the electroplating solution can spread more evenly, and the deposition of the electroplated conductive layer is also more uniform. Thereby, the generation of metal nodules and crystal aggregates on the surface of the conductive layer is effectively reduced, and the occurrence of pinholes formed due to local electroplating deficiency on the surface of the conductive layer is reduced, improving the electroplating uniformity and the thickness uniformity of the metal foil, effectively improving the yield rate of the metal foil, and at the same time improving the electroplating process efficiency and the production efficiency of the metal foil. At the same time, it is ensured that when the extremely thin metal foil produced by this electroplating is applied to the field of circuit board technology, the quality is stable during the circuit processing process, and problems such as open circuit, short circuit, and uneven circuit etching caused by too large thickness change are not likely to occur; when applied to new energy batteries, the excellent surface hydrophilicity of the carrier ensures good adhesion between the metal foil and the electrolytic material, ensuring that during the battery operation process, the electrolytic raw materials are not likely to fall off or separate and foam from the surface of the metal foil, ensuring the performance, safety, and working stability of the battery. And, in cooperation with the structural optimization of other material layers of the metal foil, the quality of the metal foil is further improved, better meeting the actual application requirements.

[0124] Example 3

[0125] An embodiment of the present 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 carrier 1 and a conductive layer 2, and one side of the conductive layer 2 away from the carrier 1 is press-fitted with the circuit board substrate.

[0126] 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 elaborated here.

[0127] By adopting the technical means of the embodiment of the present invention, through optimizing the relationship among the roughness Rz of the opposite two surfaces of the carrier of the metal foil, the arithmetic mean roughness Ra of the second surface, and the water contact angle, the surface of the carrier in contact with the conductive layer has better hydrophilicity, so that there are fewer metal nodules and pinholes on the conductive layer formed on this surface, and the performance such as the thickness uniformity and roughness of the metal foil is better, which is suitable for the production of high-frequency and high-density circuit boards, and the quality is stable during the circuit processing, and it is not easy to generate problems such as open circuit, short circuit, and uneven circuit etching due to too large thickness variation.

[0128] Example 4

[0129] An embodiment of the present invention also provides a copper-clad laminate, specifically a flexible copper-clad laminate (FCCL), also known as a flexible copper-clad laminate, and the flexible copper-clad laminate includes the metal foil as described in any of the above embodiments.

[0130] 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 elaborated here.

[0131] The structure of the flexible copper-clad laminate includes: a metal foil layer, an adhesive layer, a metal foil layer, or includes: a metal foil layer, an adhesive layer. The material of the adhesive layer can be polyimide (PI), thermoplastic polyimide (TPI), resin, etc.

[0132] Compared with the prior art, the application of the metal foil with an improved carrier as the material of the above flexible copper-clad laminate has the following advantages: by optimizing the relationship among the roughness Rz of the opposite two surfaces of the carrier of the metal foil, the arithmetic mean roughness Ra of the second surface, and the water contact angle, the surface of the carrier in contact with the conductive layer has better hydrophilicity, so that there are fewer metal nodules and pinholes on the conductive layer formed on this surface, and the performance such as the thickness uniformity and roughness of the metal foil is better, which improves the finished product yield of the manufactured copper-clad laminate product, and the performance of the product is more stable and reliable during the subsequent specific use process, and the high-frequency signal transmission loss is smaller, and the production cost is reduced.

[0133] In addition, the copper-clad laminate can also be resin-coated copper foil (RCC), which is mainly used for high-density circuits. At this time, the roughened surface of the conductive layer of the metal foil faces away from the side where the resin is coated on the copper foil.

[0134] Example 5

[0135] An embodiment of the present invention also provides a semiconductor material, which includes the metal foil described in any of the above embodiments.

[0136] 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 elaborated here.

[0137] By using the technical means of the embodiment of the present invention, when the metal foil is used as an application of the semiconductor material, by optimizing the relationship between the roughness Rz of the two opposite surfaces of the carrier of the metal foil, the arithmetic mean roughness Ra of the second surface, and the water contact angle, the surface of the carrier in contact with the conductive layer has better hydrophilicity, so that there are fewer metal nodules and pinholes in the conductive layer formed on this surface, and the performance such as the thickness uniformity and roughness of the metal foil is better. Furthermore, the quality of the metal foil product is improved, which is suitable for manufacturing semiconductor devices and integrated circuits, improving the quality and processing efficiency of semiconductor devices and integrated circuits, and reducing the defective rate of semiconductor devices and integrated circuits.

[0138] Example 6

[0139] An embodiment of the present invention also provides a negative electrode material for a battery, which includes the metal foil described in any of the above embodiments.

[0140] 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 elaborated here.

[0141] An embodiment of the present invention also provides a battery, the negative electrode material of which includes the metal foil described in any of the above embodiments.

[0142] Compared with the prior art, the application of using the metal foil as the negative electrode carrier or current collector of the above battery has the following advantages: By optimizing the relationship between the roughness Rz of the two opposite surfaces of the carrier of the metal foil, the arithmetic mean roughness Ra of the second surface, and the water contact angle, the surface of the carrier in contact with the conductive layer has better hydrophilicity, so that there are fewer metal nodules and pinholes in the conductive layer formed on this surface, and the performance of the metal foil such as thickness uniformity and roughness is better, improving the quality of the metal foil product, which is beneficial to improving the service life and safety of new energy batteries. The metal foil can be applied to the negative electrode materials of new energy batteries, such as lithium batteries and sodium-ion batteries, as the negative electrode current collector and carrier material.

[0143] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A carrier for a metal foil, characterized in that, The carrier includes opposite first and second surfaces. The roughness Rz of the first surface is greater than that of the second surface, and the arithmetic mean roughness Ra of the second surface and the water contact angle Y of the second surface satisfy the following functional relationship: Y = -3894.7×Ra 2 + 1266.6×Ra - 61.96, Ra > 0, 0 < Y < 90°, and the correlation coefficient R 2 of the functional relationship is 1.

2. The carrier for the metal foil according to claim 1, characterized in that, The water contact angle Y of the second surface is 22° to 35°.

3. The carrier of the metal foil according to claim 1, characterized in that, The arithmetic mean roughness Ra of the second surface is 0.06 to 0.265 μm.

4. The carrier of the metal foil according to any one of claims 1 to 3, characterized in that, The roughness Rz of the second surface is 3.5 to 7 μm.

5. The carrier of the metal foil according to claim 2, characterized in that, The water contact angle X of the first surface is 1.6 to 5 times that of the water contact angle Y of the second surface.

6. The carrier for the metal foil according to claim 1, characterized in that, The root mean square roughness Rq of the first surface is 0.2 to 0.42 μm.

7. A metal foil, characterized in that, A carrier including a conductive layer and the metal foil according to any one of claims 1 to 6, wherein the first surface of the carrier is the surface on the side away from the conductive layer, and the second surface of the carrier is the surface on the side close to the conductive layer.

8. The metal foil according to claim 7, wherein The material of the carrier includes at least one of the following metal elements: copper, aluminum, zinc; or, the material of the carrier is an organic film.

9. The metal foil according to claim 7, characterized in that, The surface of the conductive layer away from the carrier is a roughened surface, and the roughened surface has a number of roughened particles; and the roughness Rz of the roughened surface is less than or equal to 1.8 μm.

10. The metal foil according to claim 9, characterized in that, The material of the conductive layer includes at least one metal element among copper, aluminum, zinc, nickel, and silver and / or an alloy of at least one of them; and the thickness of the conductive layer is 1 to 5 μm.

11. The metal foil according to claim 7, characterized in that, The metal foil further includes a release layer, and the release layer is provided between the carrier and the conductive layer. The material of the release layer is a metal material, and at this time, the thickness of the release layer is 2 to 100 nm; or, the material of the release layer is a non-metal material, and at this time, the thickness of the release layer is less than or equal to 1 μm.

12. The metal foil according to claim 11, wherein, There are release layer elements remaining on the second surface of the carrier.

13. The metal foil according to claim 11, wherein There are no release layer elements remaining on the second surface of the carrier.

14. A circuit board, characterized in that, Including a circuit board substrate and the metal foil according to any one of claims 7 to 13; the surface of the conductive layer away from the carrier is pressed against the circuit board substrate.

15. A copper-clad laminate, characterized in that, The copper-clad laminate includes the metal foil according to any one of claims 7 to 13.

16. A semiconductor material, characterized in that, The semiconductor material includes the metal foil according to any one of claims 7 to 13.

17. 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 7 to 13.

18. A battery, characterized in that, The negative electrode material of the battery includes the metal foil according to any one of claims 7 to 13.

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