An extremely thin metal foil, a metal-clad laminate, a circuit board, and a battery

Abstract

The application discloses an extremely thin metal foil, a metal-clad laminate, a circuit board and a battery, wherein a plurality of protrusions are arranged on a first surface of the extremely thin metal foil, the protrusions are in a triangular shape, a ratio d of a maximum width at 3 / 4 of a height of the protrusion to a maximum width at 1 / 4 of the height of the protrusion satisfies 1 / 8<=d<=1 / 2, and when the extremely thin metal foil is attached to a carrier film, a gap is formed between the carrier film and the extremely thin metal foil, air is easily discharged during the attachment, and thus air bubbles or wrinkles are not easily generated between the carrier film and the extremely thin metal foil. In addition, the contact area of the extremely thin metal foil and the carrier film is moderate, and the extremely thin metal foil and the carrier film are not separated from each other.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of very thin metal foil, in particular to a very thin metal foil, a metal-clad laminate, a circuit board and a battery. BACKGROUND

[0002] As a new emerging comprehensive economic form, the low-altitude economy has rapidly developed in the global range in recent years. Among them, the electric vertical take-off and landing aircraft (eVTOL) has shown a rapid development momentum. In addition, the rapid development of new energy vehicles has higher requirements for the safety, stability, lightweight and energy density of the battery system. As the current collector of the negative electrode of the lithium ion battery, the copper foil plays an important role in the battery. By using thinner copper foil with good quality, the energy density of the battery can be improved, the performance of the battery can be enhanced, and the safety of the battery can be ensured. In the prior art, the thickness of the copper foil is developed from 8 microns to 6 microns, or even thinner, such as 4.5 microns and 3 microns.

[0003] Secondly, the IC carrier board is a new type of high-end PCB product developed on the basis of the HDI board, which is a technical innovation to adapt to the rapid development of electronic packaging technology, and has excellent properties such as high density, high precision, high performance, miniaturization and light and thin. The line width and distance of the IC carrier board are below 25 / 25 microns, so the copper foil used requires a thinner thickness, which is 0.1-6 microns.

[0004] With the decrease of the thickness of the copper foil, it is difficult to operate in preparation, post-process processing and application, and it is easy to break and wrinkle. Therefore, the existing technology is to paste a bearing film on the surface of the very thin copper foil. However, due to the very thin thickness of the copper foil, air bubbles are easily generated during the pasting of the bearing film, which is difficult to discharge, affecting the quality of the very thin copper foil. In order to make the very thin copper foil be widely used, it is urgent to develop a very thin metal foil which is convenient for pasting a bearing film. SUMMARY

[0005] The purpose of the embodiment of the present application is to provide a very thin metal foil which can be smoothly pasted with a bearing film and does not generate air bubbles and other defects.

[0006] To achieve the above-mentioned purpose, the embodiment of the present application provides a very thin metal foil, which comprises opposite first and second surfaces; the first surface comprises a plurality of protrusions, the width of the protrusions decreases successively away from the first surface along the protrusion height direction;

[0007] Among them, the ratio d of the maximum width at 3 / 4 height of the protrusion to the maximum width at 1 / 4 height of the protrusion satisfies 1 / 8≤d≤1 / 2.

[0008] In one embodiment, the distance between at least a part of adjacent protrusions is 5 microns to 50 microns.

[0009] In one of the embodiments, the distance between at least 70% of the adjacent protrusions is 10-20 μm.

[0010] In one of the embodiments, the roughness Rz of the first surface is 0.5-5 μm.

[0011] In one of the embodiments, the maximum width of the protrusion at 3 / 4 of the height is 0.3-5 μm.

[0012] In one of the embodiments, the included angle α between the tangent line of any point on the surface of the protrusion at 3 / 4 of the height and the horizontal plane satisfies 10°≤α≤70°.

[0013] In one of the embodiments, the ratio b of the maximum width of the protrusion at 2 / 3 of the height to the height of the protrusion at 2 / 3 of the height satisfies 1 / 20≤b≤1.

[0014] In one of the embodiments, the glossiness of the first surface is ≤300.

[0015] To achieve the above object, the embodiment of the present application further provides an attached carrier ultrathin metal foil, which comprises the ultrathin metal foil according to any one of the above.

[0016] To achieve the above object, the embodiment of the present application further provides a metal-clad laminate, which comprises the ultrathin metal foil according to any one of the above.

[0017] To achieve the above object, the embodiment of the present application further provides a circuit board, which comprises the ultrathin metal foil according to any one of the above.

[0018] To achieve the above object, the embodiment of the present application further provides a battery, which comprises the ultrathin metal foil according to any one of the above.

[0019] Compared with the prior art, the embodiment of the present application has the beneficial effect that by setting protrusions on the surface of the ultrathin metal foil and limiting the shape and size of the protrusions, there is a gap between the carrier film and the ultrathin metal foil, and the carrier film can be smoothly attached without air bubbles and falling-off phenomenon. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structural schematic diagram of a first ultrathin metal foil provided by the embodiment of the present application;

[0021] Figure 2 is a structural schematic diagram of a second ultrathin metal foil provided by the embodiment of the present application;

[0022] Figure 3is a second kind of partial enlarged view of the included angle a of the extremely thin metal foil provided by the embodiment of the present application;

[0023] Figure 4 is a structural schematic view of the first kind of extremely thin metal foil with a carrier provided by the embodiment of the present application.

[0024] wherein, 1, extremely thin metal foil; 2, protrusion; 3, carrier film; 4, anti-oxidation layer; 11, first surface; 12, second surface. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0026] Please refer to Figure 1 , Figure 1 is a structural schematic view of an extremely thin metal foil according to an embodiment of the present application. The embodiment of the present application provides an extremely thin metal foil, wherein the extremely thin metal foil 1 comprises opposite first and second surfaces 11 and 12; the first surface 11 comprises a plurality of protrusions 2, and the widths of the protrusions 2 gradually decrease away from the first surface 11 along the height direction of the protrusions.

[0027] wherein, the ratio d of the maximum width at 3 / 4 height of the protrusion 2 to the maximum width at 1 / 4 height of the protrusion 2 satisfies 1 / 8≤d≤1 / 2.

[0028] In the embodiment of the present application, by arranging a plurality of protrusions 2 on the first surface 11 of the extremely thin metal foil 1, and the protrusions 2 are in a "triangular shape", the ratio d of the maximum width at 3 / 4 height of the protrusion 2 and the maximum width at 1 / 4 height of the protrusion 2 satisfies 1 / 8≤d≤1 / 2, so that when the bearing film 3 is attached, there is a gap between the bearing film 3 and the extremely thin metal foil 1, which is beneficial for air to be discharged when attached, and further, the bearing film 3 and the extremely thin metal foil 1 are not prone to produce bubbles or wrinkles and other defects. By limiting the ratio d of the maximum width at 3 / 4 height of the protrusion 2 and the maximum width at 1 / 4 height of the protrusion 2 to be within the range of 1 / 8≤d≤1 / 2, the shape and size of the protrusion 2 are within a suitable range, and the protrusion 2 will not be in a sharp state due to the too large ratio d, although there is enough gap between the bearing film 3 and the extremely thin metal foil 1, but due to the protrusion 2 in a sharp state, the contact area with the bearing film 3 is small, and abnormal phenomena such as attachment separation and delamination occur; and the protrusion 2 will not be too flat due to the too small ratio d, so that the gap between the bearing film 3 and the extremely thin metal foil 1 is too small, which is not conducive to the discharge of air when attached, and further, bubbles and wrinkles and other defects are produced. Therefore, in the embodiment of the present application, by arranging a plurality of protrusions 2 on the first surface 11 of the extremely thin metal foil 1, and the protrusions 2 are in a "triangular shape", and further limiting the ratio d of the maximum width at 3 / 4 height of the protrusion 2 and the maximum width at 1 / 4 height of the protrusion 2 to satisfy 1 / 8≤d≤1 / 2, so that when the extremely thin metal foil 1 is attached with the bearing film 3, there is a gap between the bearing film 3 and the extremely thin metal foil 1, which is beneficial for air to be discharged when attached, and further, the bearing film 3 and the extremely thin metal foil 1 are not prone to produce bubbles or wrinkles and other defects, and at the same time, the contact area of the extremely thin metal foil 1 and the bearing film 3 is moderate, and the phenomenon of separation and delamination of the extremely thin metal foil 1 and the bearing film 3 will not occur. Optionally, the ratio d of the maximum width at 3 / 4 height of the protrusion 2 and the maximum width at 1 / 4 height of the protrusion 2 can be any one of 1 / 8, 2 / 7, 3 / 8 or 1 / 2 or an interval composed of any two values.

[0029] Preferably, the maximum width at 3 / 4 height of the protrusion 2 is 0.3-5 μm.

[0030] It should be noted that the thickness of the extremely thin metal foil 1 is 0.5-9 μm. The extremely thin metal foil 1 can be at least one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, the protrusion 2 can be at least one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the material of the extremely thin metal foil 1 and the protrusion 2 can be the same or different. Preferably, the material of the extremely thin metal foil 1 and the protrusion 2 is the same, and is at least one of aluminum, titanium, iron, nickel, chromium or copper.

[0031] In the embodiments of the present application, the forming method of the protrusion 2 comprises at least one of a green foil technology, a green foil and post-processing technology, a chemical etching method, a laser micro-nano processing technology, and a polishing technology.

[0032] Specifically, in the embodiments of the present application, the forming method of the protrusion 2 adopts the green foil technology, mainly by adjusting the formula of the green foil plating solution and adjusting the additives to make the protrusion 2 on the non-titanium roller surface in a suitable range. For example, the plating solution contains Cu with a concentration of 50-80 g / L, H2SO4 with a concentration of 100-160 g / L, chloride ions with a concentration of 1-10 mg / L, collagen with a concentration of 100 mg / L, modified hydroxyethyl fiber with a concentration of 15-20 mg / L, polysulfur organic sulfonic acid with a concentration of 1-10 mg / L, and pure water, the electrolytic green foil electrolyte temperature is 52°C, the current density is 10 A / dm 2+ 2 .

[0033] Further, the forming method of the protrusion 2 is the green foil and post-processing technology, which forms a copper foil through the green foil technology and forms a specific protrusion 2 on the surface of the copper foil through the post-processing technology. The protrusion 2 can be formed on the titanium roller surface or on the non-titanium roller surface. The shape and size of the protrusion 2 are formed by the joint action of the green foil and the post-processing.

[0034] Further, the forming method of the protrusion 2 is the chemical etching method, which immerses or sprays an extremely thin metal foil in chemical medicine water and performs directional etching through the type of etching liquid to form the protrusion 2 provided in the present application. The etching liquid can be an iron chloride system, an ammonium persulfate system, an acidic copper chloride system, etc.

[0035] Further, the forming of the protrusion 2 adopts the micro-nano processing technology, which is a physical method for manufacturing a micro-size technology on the surface of an extremely thin metal foil. It includes electron beam lithography technology or ion beam etching technology. The electron beam lithography technology is to use a high-energy electron beam to scan and expose on the surface of the copper foil, and to realize accurate drawing of the pattern by controlling the scanning path and dose of the electron beam. The ion beam etching technology is to focus the high-energy ion beam generated by the ion source to the surface of the copper foil, and to remove the copper atoms from the surface by the collision between the ions and the copper atoms, so as to realize the etching processing of the copper foil surface, and to accurately control the depth and shape of the etching.

[0036] ​Further, the forming of the protrusions 2 employs polishing techniques, including mechanical polishing, abrasive blasting polishing, etc. Mechanical polishing is to cover the surface of the copper foil with a mask having a specific pattern, which can be photoresist, polymer film, etc. Using photolithography or other plate-making techniques, the pattern of the protrusions to be formed is made on the mask. Then, using mechanical polishing tools such as sandpaper, grinding wheels, etc., the copper foil area not covered by the mask is polished. The covered area is not polished due to the protection of the mask, while the copper in the uncovered area is gradually polished off, so that the area under the mask is relatively protruding, thereby forming the protrusion pattern. Abrasive blasting polishing is to shoot high-speed abrasive particles at the surface of the copper foil. A template with protrusion pattern is placed under the copper foil, with a certain gap between the template and the copper foil. When the abrasive is sprayed onto the surface of the copper foil, the abrasive polishing effect on the copper foil area corresponding to the protruding part of the template is relatively weak due to the obstruction of the template, while the other areas are quickly polished by the abrasive to remove the material. As the polishing proceeds, the copper foil area corresponding to the protruding part of the template gradually forms a relatively protruding structure. By adjusting the type of abrasive, the spraying pressure, the spraying angle, and the shape and size of the template, etc., the shape and height of the protrusions can be controlled.

[0037] Further, in the embodiments of the present application, the distance between at least part of the adjacent protrusions 2 is 5-50 μm. By limiting the distance between the adjacent protrusions 2 to 5-50 μm, the extremely thin metal foil 1 cannot penetrate between the adjacent protrusions 2 when it is pressed with other materials, thereby reducing the peeling strength, and the rivet effect is weakened when the extremely thin metal foil 1 is pressed with other materials, thereby reducing the peeling strength. Therefore, limiting the distance between the adjacent protrusions 2 to 5-50 μm is beneficial to the adhesion of the surface of the extremely thin metal foil 1. Optionally, the distance between the adjacent protrusions 2 is any one of 5, 7, 10, 20, 30, 40 or 50 μm or an interval formed by any two of them.

[0038] Preferably, the distance between adjacent protrusions 2 is 10-20 μm, and the proportion of the distance between adjacent protrusions 2 being 10-20 μm is greater than 70%. In the embodiment, the proportion of the distance between adjacent protrusions 2 being 10-20 μm is greater than 70%, so that the number of protrusions 2 with a distance of 10-20 μm per unit area is in a suitable range. If the number is too small, the riveting effect of the protrusions 2 is not obvious when the ultra-thin metal foil 1 is pressed with other materials, and the effect of improving the peeling strength is not great. Therefore, the proportion of the distance between adjacent protrusions 2 being 10-20 μm is limited to greater than 70%, which is beneficial to improve the riveting effect of the protrusions 2 and further improve the adhesion of the surface of the ultra-thin metal foil 1. Alternatively, the proportion of the distance between adjacent protrusions 2 being 10-20 μm can be any one of 70%, 80%, 85%, 90%, or 100% or an interval formed by any two of them.

[0039] It is worth noting that in the embodiment, the roughness Rz of the first surface 11 is 0.5-5 μm. The roughness Rz of the first surface 11 of the ultra-thin metal foil 1 is limited to a suitable range, so that when the ultra-thin metal foil 1 is attached to the carrier film 3, the roughness is not too small, which causes insufficient gap between the carrier film 3 and the ultra-thin metal foil 1 to better exhaust air, resulting in a small amount of air bubbles or wrinkles. At the same time, the roughness is not too large, which causes the carrier film 3 to mainly contact the protrusions 2, resulting in poor attachment and falling off. When the ultra-thin metal foil 1 is used in a circuit board, if the roughness of the first surface 11 of the ultra-thin metal foil 1 is too large, the dry film cannot be completely removed during the circuit board manufacturing process, which affects the processing of the next process and causes circuit quality problems. Therefore, the roughness Rz of the first surface 11 of the ultra-thin metal foil 1 is limited to 0.5-5 μm, so that when the carrier film 3 is attached, there is a gap between the carrier film 3 and the ultra-thin metal foil 1, which facilitates better air exhaust and avoids a small amount of air bubbles or wrinkles. At the same time, it ensures that the carrier film 3 does not fall off abnormally during attachment. When the ultra-thin metal foil 1 is used in a circuit board, the dry film can be smoothly removed after the dry film is attached, which ensures the quality of the circuit processing. Alternatively, the roughness of the first surface 11 of the ultra-thin metal foil 1 can be any one of 0.5 μm, 1 μm, 1.5 μm, 1.8 μm, 2 μm, 3 μm, 3.5 μm, or 5 μm or an interval formed by any two of them.

[0040] It is worth mentioning that the ratio b of the maximum width at 2 / 3 height of the protrusion 2 to the height at 2 / 3 height of the protrusion 2 satisfies 1 / 20≤b≤1. By further limiting the ratio b of the maximum width at 2 / 3 height of the protrusion 2 to the height at 2 / 3 height of the protrusion 2 satisfies 1 / 20≤b≤1, the shape and size of the protrusion 2 are more conducive to solving the technical problems of the present application. If the ratio b is too small, the protrusion 2 will be too narrow and sharp, which on the one hand is easy to scratch the carrier film 3, and even the protrusion 2 is deformed or broken, on the other hand makes the gap between the extremely thin metal foil 1 and the carrier film 3 too large, resulting in delamination and falling off during the lamination of the carrier film 3. At the same time, if the ratio b is too large, the protrusion 2 will be too wide and short, which results in that the gap between the extremely thin metal foil 1 and the carrier film 3 is not large enough during the lamination of the carrier film 3, and the air exhaust effect is not good during the lamination of the carrier film 3, resulting in that some bubbles or wrinkles are generated. Therefore, by limiting the ratio b of the maximum width at 2 / 3 height of the protrusion 2 to the height at 2 / 3 height of the protrusion 2 in the range of 1 / 20≤b≤1, it can be ensured that no bubbles or wrinkles or even falling off phenomenon occurs during the lamination of the carrier film 3, and the lamination quality and reliability are improved.

[0041] Reference Figure 2 , Figure 2 is another extremely thin metal foil provided by the embodiment of the present application. In the embodiment of the present application, the horizontal angle α of the tangent at any point on the surface at 3 / 4 height of the protrusion 2 satisfies 10°≤α≤70°( Figure 3is the local enlargement of the included angle a). When the ultra-thin metal foil 1 is attached to the carrier film 3, the shape and size of the top region of the protrusion 2 are very critical. The top region of the protrusion 2 needs to be relatively rounded so that the bonding force between the ultra-thin metal foil 1 and the carrier film 3 is controlled within a suitable range. In the embodiment of the present application, the tangent line of any point on the surface of the protrusion 2 at 3 / 4 height is limited to a range of 10°≤a≤70° with respect to the horizontal. On the one hand, if the included angle a is too small, the top region of the protrusion 2 is relatively sharp, which is not conducive to attaching the carrier film 3, resulting in too weak bonding force between the ultra-thin metal foil 1 and the carrier film 3, which is easy to fall off and delaminate. On the other hand, if the included angle a is too large, the top region of the protrusion 2 is too rounded, resulting in too large bonding force between the ultra-thin metal foil 1 and the carrier film 3, which is difficult to peel off or causes peeling wrinkles or damage in subsequent processing or application, thereby limiting the use of the ultra-thin metal foil 1. Therefore, limiting the tangent line of any point on the surface of the protrusion 2 at 3 / 4 height to 10°≤a≤70° with respect to the horizontal controls the bonding force between the ultra-thin metal foil 1 and the carrier film 3 within a suitable range, avoids the phenomenon of falling off or peeling off in subsequent processing, and ensures the use reliability of the ultra-thin metal foil 1. Optionally, the tangent line of any point on the surface of the protrusion 2 at 3 / 4 height can be any one of 10°, 20°, 25°, 35°, 45°, 60° or 70° or an interval formed by any two of them.

[0042] Further, in the embodiment of the present application, the glossiness of the first surface 11 is ≤300. If the glossiness of the first surface 11 is too large, it is easy to slip during production or processing, and running or wrinkling occurs. Therefore, limiting the glossiness of the first surface 11 of the ultra-thin metal foil 1 to ≤300 can avoid slipping or wrinkling during production or processing, thereby improving the processability of the ultra-thin metal foil 1. Preferably, the glossiness of the first surface 11 is 100-250, which can avoid production slipping and also meet the smooth attachment of the carrier film 3.

[0043] It is worth noting that in combination Figure 2 , the first surface 11 and / or the second surface 12 are provided with an anti-oxidation layer 4. It is used to prevent the ultra-thin metal foil 1 from oxidizing and affecting the quality. It can be understood that if the anti-oxidation layer 4 is not provided, the surface of the metal layer 1 is easy to oxidize under the conditions of temperature, water vapor, corrosive gas, etc., resulting in abnormal use in the subsequent use; therefore, in the embodiment of the present application, the anti-oxidation layer 4 is provided on the surface of the ultra-thin metal foil 1, which can hinder the oxidation reaction of temperature, water vapor, corrosive gas and other substances with the ultra-thin metal foil 1, thereby protecting the ultra-thin metal foil 1 and improving the quality performance.

[0044] Specifically, the type of the anti-oxidation layer 4 is not limited by the material of the ultra-thin metal foil 1, and the anti-oxidation layer 4 is selected from at least one of organic anti-oxidation layer, inorganic anti-oxidation layer, and metal anti-oxidation layer.

[0045] See Figure 4 , Figure 4 The second aspect of the present invention provides an ultrathin metal foil with a carrier, wherein the ultrathin metal foil with a carrier includes the ultrathin metal foil described in any embodiment of the first aspect.

[0046] It should be noted that, in this embodiment of the invention, the bonding force between the ultra-thin metal foil 1 and the carrier film 3 is 0.05-0.3 N / cm. Controlling the bonding force between the ultra-thin metal foil 1 and the carrier film 3 within 0.05-0.3 N / cm ensures that the bonding force is within a suitable range. Too low a bonding force would prevent the ultra-thin metal foil 1 from delaminating from the carrier film 3, leading to contamination of the first surface 11 of the ultra-thin metal foil 1 or severe delamination, making subsequent processing impossible. Conversely, too high a bonding force would prevent the carrier film 3 from being difficult to peel off during use, affecting the quality of the ultra-thin metal foil 1 and processing efficiency. Therefore, by controlling the bonding force between the ultra-thin metal foil 1 and the carrier film 3 to 0.05-0.3 N / cm, delamination between the ultra-thin metal foil 1 and the carrier film 3 can be prevented, and the film can be easily peeled off, ensuring the processing stability of the ultra-thin metal foil 1. Preferably, the bonding force between the ultra-thin metal foil 1 and the carrier film 3 is 0.08-0.15 N / cm.

[0047] A third aspect of the present invention also provides a metal-clad laminate, wherein the metal-clad laminate comprises the ultrathin metal foil described in any of the above embodiments.

[0048] A fourth aspect of the present invention also provides a circuit board comprising the ultrathin metal foil described in any of the above embodiments.

[0049] A fifth aspect of the present invention also provides a battery comprising the ultrathin metal foil described in any of the above embodiments.

[0050] The thin metal foil, metal-clad laminate, circuit board and battery provided by the embodiment of the present application have the beneficial effects that: by arranging a plurality of protrusions 2 on the first surface 11 of the thin metal foil 1, and the protrusions 2 are in a triangular shape, when the bearing film 3 is attached to the thin metal foil 1, there is a gap between the bearing film 3 and the thin metal foil 1, which is beneficial to air exhaust when the bearing film 3 is attached to the thin metal foil 1, and further, the bearing film 3 and the thin metal foil 1 are not prone to produce bubbles or wrinkles and other defects. Further, the ratio d of the maximum width at 3 / 4 height of the protrusion 2 and the maximum width at 1 / 4 height of the protrusion 2 satisfies 1 / 8≤d≤1 / 2, the contact area of the thin metal foil 1 and the bearing film 3 is moderate, and the thin metal foil 1 and the bearing film 3 are not prone to fall off and delaminate, and when the bearing film 3 is attached to the thin metal foil 1, there is a gap between the bearing film 3 and the thin metal foil 1, which is beneficial to air exhaust when the bearing film 3 is attached to the thin metal foil 1, and further, the bearing film 3 and the thin metal foil 1 are not prone to produce bubbles or wrinkles and other defects.

[0051] In order to embody the beneficial effects of the thin metal foil, metal-clad laminate, circuit board and battery provided by the embodiment of the present application, the following will be described in combination with several examples and comparative examples.

[0052] Example 1:

[0053] A thin metal foil, a plurality of protrusions 2 are arranged on the first surface 11 of the thin metal foil 1, the ratio d of the maximum width at 3 / 4 height of the protrusion 2 and the maximum width at 1 / 4 height of the protrusion 2 is 1 / 8, the distance between 70% adjacent protrusions 2 is 15-20 μm, the roughness Rz of the first surface 11 is 2-2.5 μm, and the thickness of the thin metal foil is 2-3 μm.

[0054] Example 2:

[0055] The thin metal foil structure of the present embodiment is the same as that of Example 1, except that the ratio d of the maximum width at 3 / 4 height of the protrusion 2 and the maximum width at 1 / 4 height of the protrusion 2 is 3 / 7.

[0056] Example 3:

[0057] The thin metal foil structure of the present embodiment is the same as that of Example 1, except that the ratio d of the maximum width at 3 / 4 height of the protrusion 2 and the maximum width at 1 / 4 height of the protrusion 2 is 1 / 2.

[0058] Example 4:

[0059] The thin metal foil structure of the present embodiment is the same as that of Example 1, except that the distance between 80% adjacent protrusions 2 is 15-20 μm.

[0060] Example 5:

[0061] The ultra-thin metal foil structure of the present embodiment is the same as that of Embodiment 1, except that the distance between 90% of the adjacent protrusions 2 is 15-20 μm.

[0062] Embodiment 6:

[0063] The ultra-thin metal foil structure of the present embodiment is the same as that of Embodiment 1, except that the distance between 100% of the adjacent protrusions 2 is 15-20 μm.

[0064] Comparative Example 1:

[0065] An ultra-thin metal foil, wherein no protrusion is provided on the first surface 11 of the ultra-thin metal foil.

[0066] Comparative Example 2:

[0067] The ultra-thin metal foil structure of the present comparative example is the same as that of Embodiment 1, except that the ratio d of the maximum width at 3 / 4 of the height of the protrusion 2 to the maximum width at 1 / 4 of the height of the protrusion 2 is 1 / 20.

[0068] Comparative Example 3:

[0069] The ultra-thin metal foil structure of the present comparative example is the same as that of Embodiment 1, except that the ratio d of the maximum width at 3 / 4 of the height of the protrusion 2 to the maximum width at 1 / 4 of the height of the protrusion 2 is 2.

[0070] As shown in Table 1 below, the lamination quality results of the ultra-thin metal foils of Embodiments 1-6 and Comparative Examples 1-3 described above are shown.

[0071] Table 1. Lamination quality results of the ultra-thin metal foils of Embodiments 1-6 and Comparative Examples 1-3

[0072]

[0073] As can be seen, by applying the ultra-thin metal foil of the present embodiment, there is a gap between the carrier film and the ultra-thin metal foil when the carrier film is laminated, which facilitates air discharge when lamination, and thus air bubbles or wrinkles and other defects are less likely to occur between the carrier film and the ultra-thin metal foil.

[0074] In summary, by providing a plurality of protrusions on the first surface of the ultra-thin metal foil, and the protrusions being in a "triangular shape", the ratio d of the maximum width at 3 / 4 of the height of the protrusion to the maximum width at 1 / 4 of the height of the protrusion satisfies 1 / 8≤d≤1 / 2 (1 / 8, 3 / 7, 1 / 2), which facilitates air discharge when lamination, and thus air bubbles or wrinkles and other defects are less likely to occur between the carrier film and the ultra-thin metal foil; and the contact area of the ultra-thin metal foil and the carrier film is moderate, and the phenomenon of delamination of the ultra-thin metal foil and the carrier film does not occur.

[0075] Any combination of the technical features in the above-described embodiments can be made. For the sake of brevity, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combination of the technical features does not exist in contradiction, it should be considered as within the scope of the present disclosure.

[0076] The above-described embodiments only express several implementation manners of the present application, facilitate specific and detailed understanding of the technical solutions of the present application, but should not be understood as a limitation on the patent protection scope of the present application. It should be pointed out that, for ordinary skilled persons in the art, a number of modifications and improvements can be made without departing from the concept of the present application, which are all within the protection scope of the present application. It should be understood that, the technical solutions obtained by the skilled person in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided by the present application are all within the protection scope of the appended claims of the present application. Therefore, the patent protection scope of the present application should be subject to the contents of the appended claims, and the description can be used to explain the contents of the claims.

Claims

1. An ultrathin metal foil, characterized in that, The ultrathin metal foil includes a first surface and a second surface opposite to each other; the first surface includes a plurality of protrusions, the width of which decreases sequentially away from the first surface along the height direction of the protrusions; The ratio d of the maximum width at 3 / 4 of the height of the protrusion and the maximum width at 1 / 4 of the height of the protrusion satisfies 1 / 8 ≤ d ≤ 1 / 2.

2. The ultrathin metal foil as described in claim 1, characterized in that, At least some of the adjacent protrusions are 5 μm to 50 μm apart.

3. The ultrathin metal foil as described in claim 2, characterized in that, At least 70% of the adjacent protrusions are 10 μm to 20 μm apart.

4. The ultrathin metal foil as described in claim 1, characterized in that, The roughness Rz of the first surface is 0.5μm~5μm.

5. The ultrathin metal foil as described in claim 1, characterized in that, The maximum width at 3 / 4 of the height of the protrusion is 0.3~5μm.

6. The ultrathin metal foil as described in claim 1, characterized in that, The angle α between the tangent at any point on the surface at 3 / 4 of the height of the protrusion and the horizontal satisfies 10°≤α≤70°.

7. The ultrathin metal foil as described in claim 1, characterized in that, The ratio b of the maximum width at 2 / 3 of the height of the protrusion to the height at 2 / 3 of the height of the protrusion satisfies 1 / 20 ≤ b ≤ 1.

8. The ultrathin metal foil as described in any one of claims 1-7, characterized in that, The gloss level of the first surface is ≤300.

9. An extremely thin metal foil with a carrier, characterized in that, Including the ultrathin metal foil as described in any one of claims 1-8.

10. A metal-clad laminate, characterized in that, Including the ultrathin metal foil as described in any one of claims 1-8.

11. A circuit board, characterized in that, Including the ultrathin metal foil as described in any one of claims 1-8.

12. A battery, characterized in that, Including the ultrathin metal foil as described in any one of claims 1-8.

Images