Ultrathin metal foil with carrier, metal-clad laminate, wiring board, and battery

Abstract

The invention discloses an ultra-thin metal foil with a carrier, a metal-clad laminated plate, a circuit board and a battery. The ultra-thin metal foil with the carrier at least comprises a bearing layer and a metal foil layer, wherein the ratio a of the flexural rigidity of the bearing layer to the flexural rigidity of the metal foil layer is more than or equal to 1 / 50 and less than or equal to 70. The ratio a of the flexural rigidity of the bearing layer to the flexural rigidity of the metal foil layer is set to be within a proper range, so that when the metal foil is attached to the carrier layer, the situation that the attaching face is uneven and air is trapped at the wrinkles due to easy deformation of the metal foil is avoided, and the situation that local collapse and air are trapped at the recesses due to easy deformation of the bearing layer is avoided; therefore, the problem of bubbles of the attached bearing layer is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-thin metal foils, and in particular to an ultra-thin metal foil, a metal-clad laminate, a circuit board and a battery. Background Art

[0002] The low-altitude economy, an emerging comprehensive economic model, has seen rapid global development across its entire industry chain in recent years. Electric vertical take-off and landing (eVTOL) vehicles have demonstrated rapid growth. The rapid development of new energy vehicles has also placed higher demands on battery system safety, stability, lightweighting, and energy density. Copper foil, as the current collector for the negative electrode in lithium-ion batteries, plays a crucial role. Thinner, high-quality copper foil can improve battery energy density, enhance performance, and ensure safety. Currently, copper foil thickness has evolved from 8μm to 6μm, and even thinner to 4.5μm, with thicknesses below 3μm.

[0003] Secondly, IC substrates are new high-end PCB products developed based on HDI boards. They are technological innovations adapted to the rapid development of electronic packaging technology and feature high density, high precision, high performance, miniaturization, and lightweight design. The line width and line spacing of IC substrates are below 25 / 25μm, so the copper foil used is required to be thinner, ranging from 0.1 to 6 microns.

[0004] As copper foil thickness decreases, it becomes difficult to handle during preparation, post-processing, and application, and is prone to defects such as breakage and wrinkling. Therefore, existing technology involves applying a carrier film to the surface of ultra-thin copper foil. However, due to the extremely thin thickness of the copper foil, bubbles are easily generated during application of the carrier film, which is difficult to remove, affecting the quality of the ultra-thin copper foil. To ensure the widespread application of ultra-thin copper foil, it is urgently needed to develop an ultra-thin metal foil with a carrier film that facilitates the application of the carrier film. Summary of the Invention

[0005] Based on this, the main purpose of the present invention is to provide an ultra-thin metal foil with a carrier, which can solve the problem that bubbles are easily generated and difficult to discharge when the ultra-thin copper foil is applied to the carrier film.

[0006] To achieve the above objectives, a first aspect of an embodiment of the present invention provides an ultra-thin metal foil with a carrier, comprising at least a carrier layer and a metal foil layer, wherein the ratio a of the bending stiffness of the carrier layer to the metal foil layer satisfies 1 / 50≤a≤70.

[0007] In one embodiment, the bending stiffness of the bearing layer is 100-6000 mN▪cm.

[0008] In one embodiment, the bending stiffness of the metal foil layer is 25-1000 mN▪cm.

[0009] In one embodiment, a ratio b of the elastic modulus of the bearing layer to the metal foil layer satisfies 1 / 60≤b≤60.

[0010] In one embodiment, the thermal expansion coefficient T1 of the carrier layer and the thermal expansion coefficient T2 of the metal foil layer satisfy 0≤|T1-T2|≤7ppm / °C.

[0011] In one embodiment, the ultra-thin metal foil with a carrier includes a transition layer, which is arranged on a side of the carrier layer close to the metal foil layer; the bending stiffness of the transition layer is between that of the carrier layer and the metal foil layer;

[0012] The ratio c of the bending stiffness of the bearing layer to the transition layer satisfies 5<c≤15, and the ratio d of the bending stiffness of the transition layer to the metal foil layer satisfies 5<d≤10.

[0013] In one embodiment, the surface roughness Rz of the side of the carrier layer close to the metal foil layer and / or the side of the metal foil layer close to the carrier layer is 0.5-6 μm.

[0014] In one embodiment, the ultra-thin metal foil with a carrier includes a peeling layer, and the peeling layer is disposed between the carrier layer and the metal foil layer.

[0015] In one embodiment, the bonding force between the carrier layer and the metal foil layer is 0.05-0.8 N / cm.

[0016] In one embodiment, at least one dielectric layer is provided on a side of the metal foil layer away from the carrier layer.

[0017] To achieve the above-mentioned object, a second aspect of an embodiment of the present invention further provides a metal-clad laminate, which comprises the ultra-thin metal foil with a carrier as described above.

[0018] To achieve the above-mentioned purpose, a third aspect of an embodiment of the present invention further provides a circuit board, which includes the ultra-thin metal foil with a carrier as described in any one of the above items.

[0019] To achieve the above-mentioned purpose, a fourth aspect of an embodiment of the present invention further provides a battery, comprising the ultra-thin metal foil with a carrier as described in any one of the above-mentioned items.

[0020] Compared with the prior art, the beneficial effect of the embodiments of the present invention is that by setting the ratio a of the bending stiffness of the carrier layer and the metal foil layer to satisfy 1 / 50≤a≤70, when the metal foil is applied to the carrier layer, the metal foil will not be easily deformed, resulting in an uneven bonding surface and air being trapped in wrinkles, nor will the carrier layer be easily deformed, resulting in local collapse and air being trapped in depressions, thereby solving the problem of bubbles in the carrier layer.

[0021] On the other hand, the thermal expansion coefficient T1 of the carrier layer and the thermal expansion coefficient T2 of the metal foil layer are controlled to satisfy 0≤|T1-T2|≤7ppm / °C, so that the thermal expansion coefficients of the carrier layer and the metal foil layer are close. When the temperature changes, the shear stress generated between the two is small, the deformation tends to be consistent, and it is not easy to generate small gaps, thereby improving quality reliability and processing efficiency.

[0022] On the other hand, a transition layer is provided on the side of the bearing layer close to the metal foil layer, so that the bending stiffness of each layer is stepped, reducing stress concentration and preventing air from being "trapped" in tiny gaps where stress is concentrated, making it difficult to discharge and forming air bubbles, which affects the quality of the subsequent ultra-thin metal foil. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following briefly introduces the drawings required for the embodiments or the prior art description. The drawings are only used to illustrate the preferred embodiments and are not considered to limit the present application. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0024] Figure 1 A schematic structural diagram of a first type of ultra-thin metal foil with a carrier provided by an embodiment of the present invention;

[0025] Figure 2 A schematic structural diagram of a second type of ultra-thin metal foil with a carrier provided by an embodiment of the present invention;

[0026] Figure 3 A schematic structural diagram of a third type of ultra-thin metal foil with a carrier provided by an embodiment of the present invention;

[0027] Figure 4 A schematic structural diagram of a fourth type of ultra-thin metal foil with a carrier provided by an embodiment of the present invention;

[0028] Figure 5 This is a schematic structural diagram of a fifth type of ultra-thin metal foil with a carrier provided by an embodiment of the present invention.

[0029] Among them, 1. bearing layer; 2. metal foil layer; 3. transition layer; 4. peeling layer; 5. dielectric layer; 6. anti-oxidation layer. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of this application more clear and to provide a more thorough and comprehensive understanding of the disclosure of this application, the following will provide a clear and complete description of the technical solutions of this application in conjunction with the specific embodiments of this application and the corresponding drawings. The described embodiments are only part of the embodiments of this application, not all of them.

[0031] The following is a detailed description of the implementation of this application in conjunction with the accompanying drawings. This embodiment is implemented based on the technical solution of this application, and provides a detailed implementation method and specific operation process, but the scope of protection of this application is not limited to the following embodiment.

[0032] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0033] It is worth noting that an embodiment of the present invention provides an ultra-thin metal foil with a carrier. In practical applications, for example, the ultra-thin metal foil is used in the field of circuit boards. The metal foil layer is pressed against the substrate of the circuit board, and the carrier layer is torn off, leaving the metal foil layer on the substrate. The desired circuit is then formed through a circuit board processing process. For example, in the field of electromagnetic shielding, the ultra-thin metal foil is composited with other materials. For example, in the field of copper-clad laminates, the ultra-thin metal foil is laminated on a base film at high temperature to make a metal-clad laminate. For example, in the field of batteries, it can be used as a negative current collector or positive current collector for lithium batteries, or composited with other base films to form a composite current collector.

[0034] See also Figure 1 , Figure 1 Schematic diagram of the structure of an ultra-thin metal foil with a carrier provided by an embodiment of the present invention. In this embodiment of the present invention, the ultra-thin metal foil with a carrier includes at least a carrier layer 1 and a metal foil layer 2, and the ratio of the bending stiffness of the carrier layer 1 to the metal foil layer 2 satisfies 1 / 50≤a≤70.

[0035] In the embodiment of the present invention, because the metal foil layer 2 is too thin to be processed independently, the carrier layer 1 is composited with the metal foil layer 2, with the carrier layer 1 acting as a support for the metal foil 2. By limiting the ratio a of the flexural rigidity of the carrier layer 1 to that of the metal foil layer 2 to 1 / 50≤a≤70, on the one hand, an excessively small ratio a will prevent the carrier layer 1 from having low flexural rigidity and being easily deformed when composited with the carrier layer 1, thereby causing local collapse of the carrier layer 1 and trapping air in the depressions, resulting in air bubbles and affecting the quality and reliability of the metal foil; on the other hand, an excessively large ratio a will prevent the metal foil layer 2 from deforming when composited with the carrier layer 1, resulting in an uneven bonding surface and air trapped in wrinkles. Therefore, by limiting the flexural stiffness ratio a of the carrier layer 1 to the metal foil layer 2 to the above range, when the metal foil is applied to the carrier layer, deformation of the carrier layer 1 will not cause local collapse of the carrier layer 1, trapping air in the depressions. Deformation of the metal foil layer 2 will also prevent unevenness of the bonding surface, trapping air in wrinkles, thereby solving the problem of air bubbles when applying the carrier layer. Alternatively, the ratio a can be any one of 1 / 50, 1 / 20, 1 / 10, 1, 5, 10, 20, 30, 40, 50, 60, and 70, or an interval consisting of any two of these values.

[0036] It should be noted that flexural stiffness is the ability of an object to resist its bending deformation. The sample size is 25cm×2.5cm, and there are 10 samples. First, test the mass of the 10 samples, calculate the mass per unit area, and take the average value; then adjust the level of the instrument, place the prepared sample horizontally on the test bench, and make the front of the sample coincide with the edge of the test bench, and the pressure plate completely clamp the test sample. The pressure plate drives the sample forward until the sample sags and blocks the detection line. The instrument stops automatically, and the extended length of the 10 samples tested is recorded separately, and the average value is taken. Calculate the flexural stiffness according to the flexural stiffness calculation formula. The formula for flexural stiffness is as follows: G=m*C 3 *10 -2 , where G is the bending stiffness per unit width, in mN / cm, and m is the average mass per unit area of ​​10 specimens, in g / m 2 , C is the average extension length of 10 specimens, in cm.

[0037] In this embodiment of the present invention, the extremely thin metal foil layer 2 is too thin to be directly processed and cannot be used directly in an application. Therefore, a carrier film is required. Therefore, the carrier layer 1 serves as a support for the metal foil layer 2. The thickness of the carrier layer 1 is 7 to 100 μm. The material of the carrier layer 1 can be a metal film or an organic polymer film. The carrier layer 1 can be selected from at least one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold, or at least one of PET (polyethylene terephthalate), PI (polyimide), PVC (polyvinyl chloride), PP (polypropylene), PEN (polyethylene terephthalate-2,6-naphthalate), TPU (thermoplastic polyurethane elastomer), PE (polyethylene), PA (polyamide), and PLA (polylactic acid, a biodegradable plastic).

[0038] In an embodiment of the present invention, the metal foil layer 2 is used to fabricate circuits or as a battery current collector. The thickness of the metal foil layer 2 is 0.5-18 μm. The metal foil layer 2 is selected from at least one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold. For example, the ultra-thin metal foil used for an IC substrate is copper; the ultra-thin metal foil used for the negative electrode current collector is copper; and the ultra-thin metal foil used for the positive electrode current collector is aluminum.

[0039] Preferably, the bending stiffness of the bearing layer 1 is 100-6000 mN▪cm.

[0040] It is worth noting that the supporting layer 1 is made of metal, and the required bending stiffness can be achieved by adjusting the metal forming process, controlling the grain size and the type, proportion, and size of the reinforcing phase; the supporting layer 1 is an organic polymer film, and the required bending stiffness can be achieved by adjusting the film forming process parameters, controlling the molecular chain length, crystallinity, or adding fillers to the organic polymer film.

[0041] Preferably, the bending stiffness of the metal foil layer 2 is 25-1000 mN·cm.

[0042] In an embodiment of the present invention, the ratio b of the elastic moduli of the carrier layer 1 and the metal foil layer 2 satisfies 1 / 60 ≤ b ≤ 60. By limiting the ratio b of the elastic moduli of the carrier layer 1 to the metal foil layer 2 to the above range, the difference in elastic moduli between the two layers, which may occur due to an excessively large or small ratio b, is avoided. This could lead to asynchronous deformation of the carrier layer 1 and the metal foil layer 2 during application, resulting in a small gap between the layers and the formation of air bubbles between the carrier layer 1 and the metal foil layer 2, thus affecting quality reliability and processing efficiency. Therefore, limiting the ratio b of the elastic moduli of the carrier layer 1 to the metal foil layer 2 to the above range ensures that the elastic moduli of the two layers are close and that deformation tends to be synchronous. This reduces the likelihood of small gaps between the layers during application, thus preventing the formation of air bubbles and improving quality reliability and processing efficiency. Alternatively, the ratio b can be any one of 1 / 60, 1 / 20, 1 / 10, 1, 5, 10, 20, 30, 40, 50, and 60, or an interval consisting of any two of these values.

[0043] Preferably, the elastic modulus of the bearing layer 1 is 150-6000 MPa.

[0044] Preferably, the elastic modulus of the metal foil layer 2 is 100-2000 MPa.

[0045] In an embodiment of the present invention, the thermal expansion coefficient T1 of the carrier layer 1 and the thermal expansion coefficient T2 of the metal foil layer 2 satisfy 0≤|T1-T2|≤7ppm / °C. This allows the dimensional change rate of the carrier layer 1 and the metal foil layer 2 to be within a controllable range when the temperature changes during application of the carrier layer 1. The shear stress generated between the carrier layer 1 and the metal foil layer 2 is small, the deformation tends to be consistent, and it is unlikely that small gaps will be generated when applying the carrier layer 1, thus avoiding the generation of air bubbles, thereby improving quality reliability and processing efficiency. Optionally, the absolute value of the difference between the thermal expansion coefficient T1 of the carrier layer 1 and the thermal expansion coefficient T2 of the metal foil layer 2 can be any one of 0, 1, 1.5, 3, 4, 4.5, 5, 5.5, 6, and 7ppm / °C, or an interval consisting of any two values.

[0046] Preferably, the thermal expansion coefficient of the carrier layer 1 is 10 ppm / °C to 22 ppm / °C.

[0047] Preferably, the thermal expansion coefficient of the metal foil layer 2 is 12 ppm / °C to 29 ppm / °C.

[0048] See also Figure 2 , Figure 2This is a schematic structural diagram of another ultra-thin metal foil with a carrier provided by an embodiment of the present invention. The ultra-thin metal foil with a carrier also includes a transition layer 3, which is arranged on the side of the carrier layer 1 close to the metal foil layer 2; the flexural stiffness of the transition layer 3 is between that of the carrier layer 1 and the metal foil layer 2; wherein, the ratio c of the flexural stiffness of the carrier layer 1 to the transition layer 3 satisfies 5<c≤15, and the ratio d of the flexural stiffness of the transition layer 3 to the metal foil layer 2 satisfies 5<d≤10. By arranging the transition layer 3 on the side of the carrier layer 1 close to the metal foil layer 2, the flexural stiffness of each layer is stepped, which reduces stress concentration and prevents air from being "trapped" in tiny gaps where stress is concentrated, making it difficult to discharge and forming air bubbles, which affects the quality of the subsequent ultra-thin metal foil.

[0049] It is worth noting that the ratio c of the flexural stiffness of the bearing layer 1 to the transition layer 3 satisfies 5<c≤15, and the ratio d of the flexural stiffness of the transition layer 3 to the metal foil layer 2 satisfies 5<d≤10. By limiting the ratio c of the flexural stiffness of the bearing layer 1 to the transition layer 3 to 5<c≤15, on the one hand, the ratio c is not too small, causing the flexural stiffness of the bearing layer 1 and the transition layer 3 to be close, thereby failing to achieve the stress buffering effect; on the other hand, the ratio c is not too large, causing the flexural stiffness of the transition layer 3 to be too low, making it difficult to release stress laterally and thus failing to achieve the stress buffering effect. At the same time, by ensuring that the ratio d of the flexural stiffness of the transition layer 3 to the metal foil layer 2 satisfies 5<d≤10, the flexural stiffness of the transition layer 3 and the metal foil layer 2 will not be too close due to the ratio d being too small, thus failing to buffer stress. On the other hand, the flexural stiffness difference between the transition layer 3 and the metal foil layer 2 will not be too large due to d being too large, which could cause the metal foil layer 2 to deform when laminated with the carrier layer 1, resulting in an uneven bonding surface and air being trapped in wrinkles. Therefore, by limiting the flexural stiffness ratio of the carrier layer 1, transition layer 3, and metal foil layer 2 to the above range, the flexural stiffness shows a gradient downward trend, reducing stress concentration and preventing air from being "trapped" in tiny gaps where stress concentrates, making it difficult to expel and forming air bubbles, which could affect the quality of the subsequent ultra-thin metal foil. Optionally, the ratio c can be any one of 5, 6, 7, 8, 8.8, 9, 10, 12, 13 and 15, or an interval consisting of any two values; the ratio c can be any one of 5, 5.5, 6, 7, 7.4, 8, 9 and 10, or an interval consisting of any two values.

[0050] Furthermore, transition layer 3 is selected from at least one of a PPS film layer, a PEN film layer, a polyester film layer, a polyimide film layer, a film layer formed by curing an epoxy resin ink, a film layer formed by curing a polyurethane ink, a film layer formed by curing a modified acrylic resin, or a film layer formed by curing a polyimide resin. The thickness of transition layer 3 is 0.5-5 μm, preferably 0.5-2 μm.

[0051] In one embodiment, the surface roughness Rz of the side of the carrier layer 1 close to the metal foil layer 2 and / or the side of the metal foil layer 2 close to the carrier layer 1 is 0.5-6 μm. The surface roughness Rz of the side of the carrier layer 1 close to the metal foil layer 2 and / or the side of the metal foil layer 2 close to the carrier layer 1 is limited to 0.5-6 μm, so that when the metal foil layer 2 and the carrier film 1 are attached, there is a gap between the carrier layer 1 and the metal foil layer 2, which is conducive to air discharge during attachment and ensures that defects such as bubbles or wrinkles are not easily generated between the carrier layer 1 and the metal foil layer 2. The surface roughness Rz is too small, which will cause the gap between the carrier layer 1 and the metal foil layer 2 to be too small, making it difficult for air to be discharged in time during bonding, thereby causing defects such as bubbles and wrinkles, and affecting the bonding quality. In addition, the surface roughness Rz is too large, which will cause the surface of the metal foil layer 2 to be uneven during bonding or use, making it difficult to meet high-frequency requirements, and even the uneven surface of the metal foil layer 2 will cause etching residue or uneven etching, affecting the quality reliability of the metal foil layer 2. Or the surface roughness Rz is too large, which will reduce the contact area between the carrier layer 1 and the metal foil layer 2, resulting in abnormal delamination and shedding of the carrier layer 1 and the metal foil layer 2. Therefore, the surface roughness Rz of the side of the carrier layer 1 close to the metal foil layer 2 and / or the side of the metal foil layer 2 close to the carrier layer 1 is limited to the above range. When laminating, air can be discharged to ensure that bubbles or wrinkles are not easily generated between the carrier layer 1 and the metal foil layer 2, and the surface of the metal foil layer 2 can be flat. It is ensured that the contact area between the carrier layer 1 and the metal foil layer 2 is large enough to avoid the abnormal delamination and shedding of the carrier layer 1 and the metal foil layer 2. Optionally, the surface roughness Rz can be any one of 0.5, 0.8, 1, 2, 2.5, 3, 4, 5 and 6 μm, or an interval consisting of any two values. Preferably, the surface roughness Rz of the side of the carrier layer 1 close to the metal foil layer 2 and / or the side of the metal foil layer 2 close to the carrier layer 1 is 1-1.5 μm.

[0052] See also Figure 3 , Figure 3 This is another ultra-thin metal foil with a carrier provided by an embodiment of the present invention. The ultra-thin metal foil with a carrier also includes a release layer 4 disposed between the carrier layer 1 and the metal foil layer 2. Release layer 4 acts as a release layer, further improving the release stability of the metal foil with a carrier. Release layer 4 can be an organic release layer, an inorganic release layer, or a combination of both.

[0053] Furthermore, the release layer 4 is an organic release layer, comprising at least one of a nitrogen-containing compound and a sulfur-containing compound, and may also be a low-viscosity resin. Preferably, multiple organic release layers are compounded to further improve the release stability of the carrier metal foil.

[0054] Furthermore, the bonding force between the carrier layer 1 and the metal foil layer 2 is 0.05-0.8N / cm. By limiting the bonding force between the carrier layer 1 and the metal foil layer 2 to an appropriate range, the reliability of the peeling of the carrier metal foil can be guaranteed. It will not fall off during the processing process due to too low bonding force, nor will it be impossible to peel off the entire piece normally due to too high bonding force, thereby improving the use reliability and processing efficiency of the carrier metal foil. Therefore, by limiting the bonding force between the carrier layer 1 and the metal foil layer 2 to 0.05-0.8N / cm, it can be guaranteed that the metal foil can be peeled off smoothly during processing and use, and the reliability of the peeling of the carrier metal foil can be guaranteed. Optionally, the bonding force between the carrier layer 1 and the metal foil layer 2 can be any one of 0.05, 0.1, 0.15, 0.2, 0.25, 0.35, 0.45, 0.6, 0.7 and 0.8N / cm or an interval consisting of any two values.

[0055] See also Figure 4 , Figure 4 It is another ultra-thin metal foil with a carrier provided by an embodiment of the present invention. At least one dielectric layer 5 is provided on the side of the metal foil layer 2 away from the carrier layer 1. The dielectric layer 5 serves as a dielectric layer or a bonding layer. As a dielectric layer, it can be used in the field of shielded cables to provide insulation protection. As an adhesive layer, it can be compounded with other structures to increase the peel strength between the metal foil layer 2 and the other structures. The dielectric layer 5 is selected from at least one substance selected from polyester, polyimide film, epoxy resin, polyurethane, acrylic, rubber, phenolic resin, and hot melt adhesive. The thickness of the dielectric layer 5 is 0.5-25 μm, preferably 0.5-2 μm.

[0056] It should be noted that the dielectric layer 5 is formed on the ultra-thin metal foil layer 2 by coating; alternatively, the dielectric layer 5 may be formed and then composited with the ultra-thin metal foil layer 2 .

[0057] See also Figure 5 , Figure 5This is another ultra-thin metal foil with a carrier provided by an embodiment of the present invention. In the embodiment of the present invention, the ultra-thin metal foil with a carrier further comprises an anti-oxidation layer 6, which is arranged between the carrier layer 1 and the metal foil layer 2 and / or on the side of the metal foil layer 2 away from the carrier layer 1. It is used to prevent the metal foil layer 2 from undergoing an oxidation reaction when the carrier layer 1 is torn off, thereby affecting the quality, or to prevent the metal foil layer 2 from undergoing an oxidation reaction on the side away from the carrier layer 1 during storage, thereby affecting the use of the product. It is understandable that if the anti-oxidation layer 5 is not present, the metal foil layer 2 is easily oxidized under conditions such as temperature, water vapor, and corrosive gases, resulting in abnormal circuit processing; therefore, in the embodiment of the present invention, the anti-oxidation layer 6 is arranged between the carrier layer 1 and the metal foil layer 2 and / or on the side of the metal foil layer 2 away from the carrier layer 1, which can prevent substances such as temperature, water vapor, and corrosive gases from undergoing oxidation reactions with the metal foil layer 2, thereby improving the quality and performance of the metal foil.

[0058] To achieve the above-mentioned object, a second aspect of an embodiment of the present invention further provides a metal-clad laminate, which comprises the ultra-thin metal foil with a carrier as described above.

[0059] To achieve the above-mentioned purpose, a third aspect of an embodiment of the present invention further provides a circuit board, which includes the ultra-thin metal foil with a carrier as described in any one of the above items.

[0060] To achieve the above-mentioned purpose, a fourth aspect of an embodiment of the present invention further provides a battery, comprising the ultra-thin metal foil with a carrier as described in any one of the above-mentioned items.

[0061] Compared with the prior art, the beneficial effect of the embodiments of the present invention is that by setting the ratio a of the bending stiffness of the carrier layer and the metal foil layer to satisfy 1 / 50≤a≤70, when the metal foil is applied to the carrier layer, the metal foil will not be easily deformed, resulting in an uneven bonding surface and air being trapped in wrinkles, nor will the carrier layer be easily deformed, resulting in local collapse and air being trapped in depressions, thereby solving the problem of bubbles in the carrier layer.

[0062] On the other hand, the thermal expansion coefficient T1 of the carrier layer and the thermal expansion coefficient T2 of the metal foil layer are controlled to satisfy 0≤|T1-T2|≤7ppm / °C, so that the thermal expansion coefficients of the carrier layer and the metal foil layer are close. When the temperature changes, the shear stress generated between the two is small, the deformation tends to be consistent, and it is not easy to generate small gaps, thereby improving quality reliability and processing efficiency.

[0063] On the other hand, a transition layer is provided on the side of the bearing layer close to the metal foil layer, so that the bending stiffness of each layer is stepped, reducing stress concentration and preventing air from being "trapped" in tiny gaps where stress is concentrated, making it difficult to discharge and forming air bubbles, which affects the quality of the subsequent ultra-thin metal foil.

[0064] In order to demonstrate the beneficial effects of the ultra-thin metal foil with carrier, metal-clad laminate, circuit board and battery provided by the embodiments of the present invention, several embodiments and comparative examples are described below.

[0065] Example 1:

[0066] An ultra-thin metal foil with a carrier comprises a bearing layer and a metal foil layer, wherein a ratio a of the bending stiffness of the bearing layer to the metal foil layer is 1 / 20, the bending stiffness of the bearing layer is 2000 mN / cm, the bending stiffness of the metal foil layer is 100 mN / cm, and a ratio b of the elastic modulus of the bearing layer to the metal foil layer is 2.

[0067] Example 2:

[0068] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that the ratio a of the bending stiffness of the carrier layer to the metal foil layer is 20.

[0069] Example 3:

[0070] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that the ratio a of the bending stiffness of the carrier layer to the metal foil layer is 70.

[0071] Example 4:

[0072] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that the ratio b of the elastic modulus of the carrier layer to the metal foil layer is 60.

[0073] Example 5:

[0074] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that the thermal expansion coefficient T1 of the carrier layer and the thermal expansion coefficient T2 of the metal foil layer satisfy 0≤|T1-T2|≤7ppm / °C.

[0075] Example 6:

[0076] The ultra-thin metal foil with a carrier in this embodiment is the same as that in Example 1, except that: the ultra-thin metal foil with a carrier includes a transition layer, and the transition layer is arranged on the side of the bearing layer close to the metal foil layer; the bending stiffness of the transition layer is between the bearing layer and the metal foil layer; wherein, the ratio c of the bending stiffness of the bearing layer to the transition layer is 5, and the ratio d of the bending stiffness of the transition layer to the metal foil layer is 10.

[0077] Example 7:

[0078] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that the surface roughness Rz of the side of the carrier layer close to the metal foil layer and / or the side of the metal foil layer close to the carrier layer is 0.5 μm.

[0079] Example 8:

[0080] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that the surface roughness Rz of the side of the carrier layer close to the metal foil layer and / or the side of the metal foil layer close to the carrier layer is 6 μm.

[0081] Example 9:

[0082] The ultra-thin metal foil with a carrier of this embodiment is the same as that of the embodiment 1, except that the ultra-thin metal foil with a carrier includes a peeling layer, and the peeling layer is provided between the carrier layer and the metal foil layer.

[0083] Comparative Example 1:

[0084] An ultra-thin metal foil with a carrier comprises a bearing layer and a metal foil layer, wherein a ratio a of the bending stiffness of the bearing layer to the metal foil layer is 1 / 300, the bending stiffness of the bearing layer is 30,000 mN / cm, and the bending stiffness of the metal foil layer is 10 mN / cm.

[0085] Comparative Example 2:

[0086] The ultra-thin metal foil with a carrier in this comparative example is the same as that in Example 1, except that the thermal expansion coefficient T1 of the carrier layer and the thermal expansion coefficient T2 of the metal foil layer satisfy 70≤|T1-T2|≤100ppm / °C.

[0087] Comparative Example 3:

[0088] The ultra-thin metal foil with a carrier in this comparative example is the same as that in Example 1, except that the surface roughness Rz of the side of the carrier layer close to the metal foil layer and / or the side of the metal foil layer close to the carrier layer is 10 μm.

[0089] The ultra-thin metal foils with carriers of Examples 1 to 9 and Comparative Examples 1 to 3 were subjected to a lamination test to observe appearance such as bubbles and wrinkles. The test was carried out using the same lamination process and equipment, and the test data are shown in Table 1.

[0090] Table 1. Appearance of ultra-thin metal foil with carrier for Examples 1-9 and Comparative Examples 1-3

[0091]

[0092] As can be seen from Table 1, by applying the ultra-thin metal foil with a carrier of this embodiment, it can be ensured that bubbles, wrinkles and poor appearance are not easily generated when the ultra-thin metal foil is attached to the carrier layer, thereby improving quality reliability and processing efficiency.

[0093] In summary, by setting the ratio of the flexural stiffness of the carrier layer to the metal foil layer to satisfy 1 / 50 ≤ a ≤ 70 (1 / 20, 20, 70), the metal foil is applied to the carrier layer without causing an uneven surface due to the metal foil's easy deformation, trapping air in wrinkles. It also prevents the carrier layer from collapsing locally due to its easy deformation, trapping air in depressions, thereby resolving the issue of bubbles forming during the application of the carrier layer. Furthermore, by further controlling the thermal expansion coefficients T1 of the carrier layer and T2 of the metal foil layer to satisfy 0 ≤ |T1-T2| ≤ 7ppm / °C, the thermal expansion coefficients of the carrier layer and the metal foil layer are similar. When the temperature changes, the shear stress generated between the two layers is reduced, deformation tends to be consistent, and micro-gaps are less likely to form, further improving quality reliability and processing efficiency. Furthermore, by providing a transition layer on the side of the carrier layer near the metal foil layer, the flexural stiffness of each layer is stepped, reducing stress concentration and preventing air from being trapped in micro-gaps where stress concentrates, making it difficult to expel and forming air bubbles, which can affect the quality of the subsequent ultra-thin metal foil.

[0094] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. An ultra-thin metal foil with a carrier, characterized in that It comprises at least a bearing layer and a metal foil layer, and the ratio a of the bending stiffness of the bearing layer to the metal foil layer satisfies 1 / 50≤a≤70.

2. The ultra-thin metal foil with a carrier according to claim 1, wherein: The bending stiffness of the bearing layer is 100-6000 mN▪cm.

3. The ultra-thin metal foil with a carrier according to claim 1, wherein: The bending stiffness of the metal foil layer is 25-1000 mN▪cm.

4. The ultra-thin metal foil with a carrier according to claim 1, wherein: The ratio b of the elastic modulus of the bearing layer and the metal foil layer satisfies 1 / 60≤b≤60.

5. The ultra-thin metal foil with a carrier according to claim 1, wherein: The thermal expansion coefficient T1 of the carrier layer and the thermal expansion coefficient T2 of the metal foil layer satisfy 0≤|T1-T2|≤7ppm / °C.

6. The ultra-thin metal foil with a carrier according to claim 1, wherein: The ultra-thin metal foil with a carrier includes a transition layer, which is arranged on a side of the carrier layer close to the metal foil layer; the bending stiffness of the transition layer is between that of the carrier layer and the metal foil layer; The ratio c of the bending stiffness of the bearing layer to the transition layer satisfies 5<c≤15, and the ratio d of the bending stiffness of the transition layer to the metal foil layer satisfies 5<d≤10.

7. The ultra-thin metal foil with a carrier according to any one of claims 1 to 6, characterized in that: The surface roughness Rz of the side of the carrier layer close to the metal foil layer and / or the side of the metal foil layer close to the carrier layer is 0.5-6 μm.

8. The ultra-thin metal foil with a carrier according to any one of claims 1 to 6, characterized in that: The ultra-thin metal foil with a carrier includes a peeling layer, and the peeling layer is arranged between the carrier layer and the metal foil layer.

9. The ultra-thin metal foil with a carrier according to claim 8, characterized in that The bonding force between the bearing layer and the metal foil layer is 0.05-0.8 N / cm.

10. The ultra-thin metal foil with a carrier according to any one of claims 1 to 6, characterized in that: At least one dielectric layer is provided on a side of the metal foil layer away from the carrier layer.

11. A metal-clad laminate, characterized in that: The invention comprises the ultra-thin metal foil with a carrier as claimed in any one of claims 1 to 10.

12. A circuit board, characterized in that: The invention comprises the ultra-thin metal foil with a carrier as claimed in any one of claims 1 to 10.

13. A battery, characterized in that: The invention comprises the ultra-thin metal foil with a carrier as claimed in any one of claims 1 to 10.

Images