Preparation method of ultra-thin metal foil with carrier

Abstract

The invention relates to the technical field of metal materials, and discloses a preparation method of an ultra-thin metal foil with a carrier, and the ultra-thin metal foil with the carrier comprises a carrier foil, a metal stripping layer, an organic stripping layer and an ultra-thin metal foil which are stacked in sequence, the preparation method of the ultra-thin metal foil with the carrier comprises the following steps: 1) carrying out surface treatment on at least one surface of the carrier foil; 2) performing electro-deposition on the surface of the carrier foil subjected to surface treatment to form a metal stripping layer; wherein the metal stripping layer comprises at least one element of chromium, nickel, cobalt, iron, copper and titanium; 3) immersing the carrier foil containing the metal stripping layer into an organic stripping layer solution for ultrasonic treatment to form an organic stripping layer; and 4) forming an ultra-thin metal foil on the surface of the organic stripping layer.The composite stripping layer is adopted, and ultrasonic treatment is introduced when the organic stripping layer is formed, so that the forming speed of the organic stripping layer is higher, the thickness of a film layer is more uniform, the stripping stability can be improved, and the production efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, and in particular to a method for preparing an ultra-thin metal foil with a carrier. Background Art

[0002] Electrolytic copper foil, a key foundational material, is widely used in modern technology fields such as chip packaging, printed circuit boards, and new energy devices. With the increasing demand for higher-density integrated circuits and lighter-weight power batteries, higher requirements are being placed on the thickness and performance of copper foil. In particular, the production of extremely thin copper foil is susceptible to external forces, resulting in wrinkles or tears.

[0003] To overcome these issues, the industry abandoned conventional copper foil manufacturing methods and creatively developed a technique for producing ultra-thin copper foil with a carrier. This technology, with its carrier support, can eliminate issues such as wrinkles or tears during transportation and storage. The carrier-attached method for producing ultra-thin copper foil requires a peeling layer to be formed between the carrier foil and the ultra-thin copper foil to facilitate smooth tearing after lamination.

[0004] Existing peeling layers generally include inorganic peeling layers, organic peeling layers, and composite peeling layers. The inorganic peeling layer is generally composed of a metal layer or an alloy layer. Its advantage is good stability at high temperatures, but the diffusion between the metal layer and the copper foil enhances the bonding strength of the interface, making separation difficult; the organic peeling layer can achieve good separation, but the peeling strength is uneven, affecting the stability of the extremely thin copper foil; the composite peeling layer combines the advantages of the inorganic peeling layer and the organic layer of the organic peeling layer, but the main preparation method of the organic peeling layer is still based on the static dip coating process. Because this method relies on passive diffusion and natural adsorption, the film formation speed is slow, the film formation uniformity is poor, and the preparation efficiency is low. It is difficult to meet the efficiency and quality requirements of modern production. It is urgent to improve production efficiency and quality through process innovation or equipment improvement. Summary of the Invention

[0005] Based on this, the main purpose of this application is to provide a method for preparing ultra-thin metal foil with a carrier, by using ultrasonic treatment to form an organic peeling layer to solve the current problem of uneven and inefficient organic peeling layer in the preparation process of ultra-thin metal foil with a carrier, thereby ensuring the peeling stability of the organic peeling layer and improving production efficiency.

[0006] To achieve the above objectives, an embodiment of the present invention provides a method for preparing an ultra-thin metal foil with a carrier, wherein the ultra-thin metal foil with a carrier comprises a carrier foil, a metal release layer, an organic release layer, and an ultra-thin metal foil stacked in sequence. The method for preparing the ultra-thin metal foil with a carrier comprises the following steps:

[0007] 1) forming a metal release layer by electrodeposition on a surface of a carrier foil; wherein the metal release layer comprises at least one element selected from the group consisting of chromium, nickel, cobalt, iron, copper, and titanium;

[0008] 2) immersing the carrier foil containing the metal release layer in an organic release layer solution and performing ultrasonic treatment to form an organic release layer;

[0009] 3) forming an ultra-thin metal foil on the surface of the organic release layer.

[0010] In one embodiment, before the metal release layer is formed by electrodeposition in step 1), at least one side of the carrier foil is subjected to surface treatment, wherein the surface treatment comprises at least one of polishing, oxide layer removal, and degreasing.

[0011] In one embodiment, the surface treatment of the carrier foil is performed by sequentially treating with acetone, anhydrous ethanol, and 10 vol.% dilute sulfuric acid.

[0012] In one embodiment, the metal stripping layer in step 1) is metal nickel.

[0013] In one embodiment, the electrolyte for the electrodeposition of metallic nickel includes nickel sulfate hexahydrate at a concentration of 50-300 g / L, boric acid at a concentration of 20-120 g / L, and chloride at a concentration of 20-120 g / L; the electrolyte temperature is 20-70°C, and the current density is 5-30 A / dm 2 , electrolysis time 10-200s.

[0014] In one embodiment, the organic release layer in step 2) comprises at least one substance selected from the group consisting of purine organic compounds and derivatives of purine organic compounds.

[0015] In one embodiment, the organic release layer includes at least one substance selected from the group consisting of adenine, guanine, xanthine, hypoxanthine, caffeine, and theophylline.

[0016] In one embodiment, the concentration of the organic stripping layer is 0.1 g / L-10 g / L.

[0017] In one embodiment, the ultrasonic frequency of the ultrasonic treatment in step 2) is 10-150 kHz, the ultrasonic power is 10-150 W, and the dipping time is 10-3000 s.

[0018] In one embodiment, in step 2), the carrier foil containing the metal release layer is 2-20 cm away from the bottom of the organic release layer solution.

[0019] In one embodiment, the ultra-thin metal foil in step 3) is an ultra-thin copper foil, which is formed by electrodeposition using an electrolyte having a copper concentration of 50-110 g / L, a sulfuric acid concentration of 80-120 g / L, a chloride concentration of 20-50 ppm, a hydroxyethyl cellulose concentration of ≤20 ppm, and a gelatin concentration of ≤40 ppm; the electrolyte temperature is 20-70°C, and the current density is 5-30 A / dm 2 , electrolysis time 10-200s.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: a composite peeling layer is prepared by electrodeposition on the surface of a carrier foil, and an organic peeling layer solution is dip-coated on the surface of the metal peeling layer to form an organic peeling layer, so that the metal peeling layer forms a strong interface bond with the carrier foil, and the organic peeling layer forms a weak interface bond with the ultra-thin metal foil, thereby achieving differentiated control of the interface strength and enabling the ultra-thin metal foil to be peeled off; at the same time, in the preparation process of the dip-coated organic peeling layer, ultrasonic treatment is introduced to promote the formation of the organic peeling layer, so that the organic peeling layer is formed faster, the film layer is thicker and more uniform, the production efficiency is high, the peeling stability can be improved, and the production efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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:

[0022] Figure 1 This is a flow chart of the steps of a method for preparing an ultra-thin metal foil with a carrier according to an embodiment of the present invention;

[0023] Figure 2 This is a flow chart of the surface treatment steps of a carrier foil according to an embodiment of the present invention;

[0024] Figure 3 This is a schematic structural diagram of an ultra-thin metal foil with a carrier according to an embodiment of the present invention.

[0025] Among them, 1. carrier foil; 2. composite peeling layer; 21. metal peeling layer; 22. organic peeling layer; 3. ultra-thin metal foil; 4. anti-oxidation layer. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] In the description of the specification and claims, it should be understood that the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are 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 therefore cannot be understood as a limitation on the embodiments of the present invention.

[0028] Furthermore, the terms "first," "second," and so on, in the specification and claims, are used solely for descriptive purposes to distinguish between identical technical features and are not to be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referenced, nor do they necessarily describe a sequential or chronological order. The terms are interchangeable where appropriate. Thus, a feature qualified as "first" or "second" may explicitly or implicitly include at least one of those features.

[0029] See Figure 1 , Figure 1 A flowchart showing the steps of a method for preparing an ultra-thin metal foil with a carrier according to an embodiment of the present invention is provided. An embodiment of the present invention provides a method for preparing an ultra-thin metal foil with a carrier, wherein the ultra-thin metal foil with a carrier comprises a carrier foil 1, a metal peeling layer 21, an organic peeling layer 22 and an ultra-thin metal foil 3 (such as Figure 3 ), the preparation method of the ultra-thin metal foil with a carrier comprises the following steps:

[0030] S10: Electrodepositing a metal release layer 21 on the surface of the carrier foil 1; wherein the metal release layer 21 includes at least one element selected from the group consisting of chromium, nickel, cobalt, iron, copper, and titanium;

[0031] S20: immersing the carrier foil containing the metal release layer in an organic release layer solution and performing ultrasonic treatment to form an organic release layer 22;

[0032] S30: forming an ultra-thin metal foil 3 on the surface of the organic release layer.

[0033] The above-mentioned method for preparing an ultra-thin metal foil with a carrier comprises electrodepositing a metal release layer 21 on the surface of a carrier foil 1, then dip-coating an organic release layer solution on the surface of the metal release layer 21 to form an organic release layer 22, thereby forming a composite release layer 2. This method ensures a strong interfacial bond between the metal release layer 21 and the carrier foil 1, while a weak interfacial bond between the organic release layer 22 and the ultra-thin metal foil 3 is achieved, achieving differentiated control of the interfacial strength and enabling release of the ultra-thin metal foil 3. Furthermore, during the dip-coating process of the organic release layer 22, ultrasonic treatment is introduced. The ultrasonic waves induce high-frequency vibrations in the liquid, generating microscale turbulence, breaking the surface tension constraints of the solution and spreading it into a film. Ultrasonic waves produce periodic pressure changes in the liquid, forming tiny vacuum bubbles. These bubbles expand during negative pressure periods and collapse violently during positive pressure periods, generating localized high pressure and high-speed microjets that scour the carrier foil surface, removing adsorbed bubbles and contaminants and enhancing the uniformity of the release material's adhesion. Furthermore, cavitation energy breaks down the oxide layer on the carrier foil surface, exposing fresh active sites and promoting chemical bonding between the release layer molecules. This further promotes the formation of the organic peeling layer, makes the organic peeling layer faster to form, makes the film thicker and more uniform, increases production efficiency, improves peeling stability, and increases production efficiency.

[0034] It should be noted that carrier foil 1 serves as a support for the ultra-thin metal foil 3. The thickness of carrier foil 1 is 12 to 50 microns. The material of carrier foil 1 can be any one of zinc, iron, aluminum, cobalt, copper, titanium, nickel, chromium, silver, and gold.

[0035] In one embodiment, before electrodeposition of the metal release layer 21, at least one side of the carrier foil 1 is surface treated. The surface treatment includes at least one of polishing, oxide layer removal, and degreasing. The surface treatment of the carrier foil 1 is intended to optimize the surface condition of the carrier foil 1 and facilitate the preparation of a uniform and dense release layer. Polishing involves mechanical grinding to remove surface material or electrolytic polishing to selectively dissolve microscopic protrusions, achieving atomic-level flatness. Oxide layer removal involves direct removal of the oxide layer through acid etching or electrochemical reduction, removing the insulating barrier and improving the conductivity of the carrier foil, facilitating the electrodeposition of the metal release layer. Furthermore, the newly formed metal surface is chemically active, making it easier to form chemical bonds with the metal release layer. Degreasing involves dissolving non-polar contaminants with organic solvents or saponifying grease with alkaline degreasing solutions to form water-soluble substances, eliminating organic contaminants and removing organic matter such as grease, fingerprints, and rust inhibitors adsorbed during production, transportation, or storage. This increases surface energy and prevents the formation of a weak interface between the carrier foil and the metal release layer, which can easily lead to delamination. The above treatment methods may also be used in combination to form a uniform metal release layer on the surface of the carrier foil.

[0036] See Figure 2 , Figure 2The following is a flow chart showing the surface treatment steps of a carrier foil according to an embodiment of the present invention. The surface of the carrier foil is treated in sequence using acetone, anhydrous ethanol, and 10 vol.% dilute sulfuric acid, specifically including:

[0037] S111: Immerse the carrier foil in acetone for cleaning, take it out and blow dry it with nitrogen;

[0038] S112: Immerse the carrier foil in anhydrous ethanol for cleaning;

[0039] S113: Soak in 10 vol.% dilute sulfuric acid at room temperature, rinse with plenty of deionized water, and blow dry with nitrogen or vacuum dry.

[0040] In an embodiment of the present invention, the carrier foil 1 is immersed in acetone for 5–10 minutes to remove organic contaminants. Acetone, as a non-polar solvent, can effectively dissolve most organic impurities; the foil is then removed and blown dry with nitrogen. To remove acetone residue and polar contaminants, the carrier foil is immersed in anhydrous ethanol for 3–5 minutes to further clean the surface. Ethanol has both polar and non-polar groups, which can remove residual organic matter and dehydrate it. Finally, it is immersed in 10 vol.% dilute sulfuric acid at room temperature for 10–60 seconds to remove the oxide layer and activate the metal surface. After removal, it is rinsed with a large amount of deionized water to terminate the reaction, and then blown dry with nitrogen or vacuum dried at 80°C for 1 hour to avoid re-oxidation. Through this treatment method, a clean, low-oxidation, and highly active carrier foil 1 surface can be efficiently prepared, which is suitable for the stable and uniform deposition of the metal release layer 21.

[0041] It should be noted that the composite release layer 2 employed in the present embodiment comprises an inorganic release layer and an organic release layer. The inorganic release layer, typically composed of a metal layer or alloy layer, offers excellent stability at high temperatures. However, diffusion between the metal layer and the copper foil enhances the interfacial adhesion strength, making separation difficult. The organic release layer achieves good separation, but its peel strength is uneven, affecting the stability of the extremely thin metal foil. The composite release layer combines the advantages of both the inorganic and organic release layers.

[0042] In one embodiment, step S10: the metal release layer 21 is nickel. Nickel exhibits moderate and easily controllable interfacial adhesion to the ultra-thin metal foil 3. Adjusting the nickel plating process allows for precise control of the bond strength between the nickel layer and the ultra-thin metal foil, ensuring it remains intact during processing while allowing for easy mechanical or chemical removal during use. This resolves the conflict between durability and ease of removal. Furthermore, nickel has a high melting point, preventing it from softening or oxidizing during high-temperature processing of the ultra-thin metal foil with a carrier.

[0043] Furthermore, the electrolyte for the electrodeposition of metallic nickel includes nickel sulfate hexahydrate at a concentration of 50-300 g / L, boric acid at a concentration of 20-120 g / L, and chloride at a concentration of 20-120 g / L; the electrolyte temperature is 20-70°C, and the current density is 5-30 A / dm 2 , electrolysis time 10-200s. Through this process condition, dense and uniform thickness of metallic nickel is deposited on the surface of the carrier foil, forming a stable peeling.

[0044] In one embodiment, the organic release layer 22 in step S20 comprises at least one substance selected from the group consisting of purine organic compounds and their derivatives. Purine organic compounds and their derivatives can be used as the organic release layer, achieving a gentle release effect with a single or multiple molecular layers, minimizing damage to the extremely thin metal foil. The amino groups of purines form weak hydrogen bonds with the carrier foil, rather than strong chemical bonds, facilitating mechanical separation. Preferably, the organic release layer comprises at least one substance selected from the group consisting of adenine, guanine, xanthine, hypoxanthine, caffeine, and theophylline.

[0045] In one embodiment, the concentration of the organic stripping layer 22 is 0.1g / L-10g / L. By limiting the concentration of the organic stripping layer 22 to the above range, the stripping effect is improved. The organic stripping layer 22 will not have poor film-forming properties due to a too low concentration, resulting in incomplete stripping and damage to the extremely thin metal foil; nor will it have low peeling strength due to a too high concentration, resulting in easy delamination and detachment, which is not conducive to processing and use. Therefore, limiting the concentration of the organic stripping layer to 0.1g / L-10g / L can ensure smooth stripping without falling off. Optionally, the concentration of the organic stripping layer can be any one of 0.1g / L, 0.5g / L, 1g / L, 2g / L, 3g / L, 5g / L, 7g / L, 8g / L or 10g / L, or an interval consisting of any two values.

[0046] It is worth noting that in this embodiment of the present invention, the organic release layer 22 is formed by dip coating. This involves immersing the carrier foil 1 in a solution containing the organic release layer 22 and then slowly pulling it out. The wet film is then dried to evaporate the solvent, leaving a uniform organic release layer 22. During the dip-coating process for the organic release layer 22, ultrasonic treatment is introduced. Ultrasonic waves induce high-frequency vibrations in the liquid, generating microscale turbulence that breaks the surface tension constraints of the solution and spreads it into a film. Ultrasonic waves produce periodic pressure fluctuations in the liquid, forming tiny vacuum bubbles. These bubbles expand during negative pressure periods and collapse dramatically during positive pressure periods, generating localized high pressure and high-speed microjets that flush the carrier foil surface, remove adsorbed bubbles and contaminants, and enhance the uniformity of the release material's adhesion. Simultaneously, cavitation energy breaks down the oxide layer on the carrier foil surface, exposing fresh active sites and promoting chemical bonding between the release layer molecules. This further promotes the formation of the organic release layer 22, resulting in faster formation, thicker, more uniform films, and higher production efficiency. This improves release stability and production efficiency.

[0047] Preferably, the ultrasonic frequency of the ultrasonic treatment in step S20 is 10-150kHz, the ultrasonic power is 10-150W, and the dipping time is 10-3000s. By setting the process parameters of the ultrasonic treatment within the above range, on the one hand, the ultrasonic frequency or ultrasonic power will not be too low, resulting in insufficient ultrasonic-induced liquid vibration frequency and intensity, making it difficult to break the surface tension constraints of the solution, resulting in difficulty in spreading the organic peeling layer into a film, thereby affecting the smooth peeling of the ultra-thin metal foil with a carrier. On the other hand, the ultrasonic frequency or ultrasonic power will not be too high, resulting in difficulty in adhering the organic peeling layer to the surface of the metal peeling layer, resulting in low peel strength and easy delamination and detachment, affecting the subsequent processing and application of the ultra-thin metal foil. Therefore, setting the process parameters of the ultrasonic treatment within the above range ensures a fast film-forming speed for the organic peeling layer, ensures that the organic peeling layer is evenly spread on the surface of the metal peeling layer, forms a uniform and stable composite peeling layer, ensures complete peeling of the ultra-thin metal foil with a carrier, and achieves high production efficiency, meeting quality and efficiency requirements.

[0048] Furthermore, in step S20, the carrier foil 1 containing the metal stripping layer 21 is 2-20 cm away from the bottom of the organic stripping layer solution. When preparing the organic stripping layer by dip coating, controlling the distance between the carrier foil and the bottom of the solution within the above range is conducive to forming a uniform organic stripping layer. On the one hand, because the distance is too close to the bottom, the organic stripping layer solution will not form a precipitate at the bottom of the container due to density or solubility differences, touching the carrier foil and making the organic stripping layer uneven, or because the bubbles generated by the ultrasound will float up and affect the uniformity of the organic stripping layer. On the other hand, because the distance is too far from the bottom, the ultrasound will not induce the high-frequency vibration of the liquid to generate micro-scale turbulence and it will be difficult to act on the surface of the carrier foil, making it difficult to break the surface tension of the solution, resulting in difficulty in spreading the organic stripping layer into a film, thereby affecting the smooth stripping of the ultra-thin metal foil with the carrier. Therefore, the distance between the carrier foil and the bottom of the solution is 2-20 cm, which allows the organic release layer to spread evenly on the surface of the metal release layer, forming a uniform and stable composite release layer. This ensures a strong interfacial bond between the metal release layer and the carrier foil, while a weaker interfacial bond between the organic release layer and the ultra-thin metal foil forms. This achieves differentiated control of the interfacial strength and enables the release of the ultra-thin metal foil. Preferably, in step S20, the carrier foil containing the metal release layer is 5-15 cm from the bottom of the organic release layer solution.

[0049] It should be noted that the ultra-thin metal foil 3 is used to make circuits. The thickness of the ultra-thin metal foil 3 is 1 to 6 microns, and the material of the ultra-thin metal foil 3 can be any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.

[0050] In one embodiment, the ultra-thin metal foil 3 in step S30 is an ultra-thin copper foil, which is formed by electrodeposition using an electrolyte having a copper concentration of 50-110 g / L, a sulfuric acid concentration of 80-120 g / L, a chloride concentration of 20-50 ppm, a hydroxyethyl cellulose concentration of ≤20 ppm, and a gelatin concentration of ≤40 ppm; the electrolyte temperature is 20-70° C., and the current density is 5-30 A / dm 2 , electrolysis time 10-200s. Through this electrolyte formula and electrodeposition process, multi-component coordinated regulation and wide parameter window adaptation, precise control of the thickness of ultra-thin copper foil is achieved. The ultra-thin copper foil has high strength, low internal stress, and is pinhole-free, better meeting the high-end needs of lithium batteries, electronic circuits and other fields.

[0051] It is worth noting that the ultra-thin metal foil with carrier further comprises an anti-oxidation layer 4 (such as Figure 3), the anti-oxidation layer 4 is disposed between the organic release layer 22 and the ultra-thin metal foil 3. This prevents the ultra-thin metal foil 3 from undergoing oxidation reactions and affecting its quality when the carrier foil 1 is removed after lamination. It is understood that without the anti-oxidation layer 4, the side of the ultra-thin metal foil 3 closest to the carrier foil 1 would be susceptible to oxidation under conditions such as temperature, moisture, and corrosive gases, leading to abnormal circuit processing. Therefore, in this embodiment of the present invention, the anti-oxidation layer 4 is disposed between the organic release layer 22 and the ultra-thin metal foil 3 to prevent oxidation reactions between the side of the ultra-thin metal foil 3 closest to the carrier foil 1 and substances such as temperature, moisture, and corrosive gases, thereby improving the quality and performance of the metal foil.

[0052] The present invention provides a method for preparing an ultra-thin metal foil with a carrier. The method has the following beneficial effects: a metal stripping layer is prepared by electrodeposition on the surface of the carrier foil, and an organic stripping layer solution is dip-coated on the surface of the metal stripping layer to form an organic stripping layer, thereby preparing a composite stripping layer. This allows the metal stripping layer to form a strong interfacial bond with the carrier foil, while the organic stripping layer forms a weak interfacial bond with the ultra-thin metal foil, achieving differentiated control of the interfacial strength and enabling stripping of the ultra-thin metal foil. Furthermore, during the preparation of the dip-coated organic stripping layer, ultrasonic treatment is introduced. Ultrasonic waves induce high-frequency vibrations in the liquid, generating microscale turbulence, breaking the surface tension constraints of the solution and spreading it into a film. Ultrasonic waves produce periodic pressure changes in the liquid, forming tiny vacuum bubbles. The bubbles expand during negative pressure periods and collapse violently during positive pressure periods, generating localized high pressure and high-speed microjets that flush the surface of the carrier foil, remove adsorbed bubbles and contaminants, and enhance the uniformity of the stripping material's adhesion. Furthermore, cavitation energy can break the oxide layer on the surface of the carrier foil, exposing fresh active sites and promoting chemical bonding of the stripping layer molecules. This further promotes the formation of the organic peeling layer, makes the organic peeling layer faster to form, makes the film thicker and more uniform, increases production efficiency, improves peeling stability, and increases production efficiency.

[0053] In order to demonstrate the beneficial effects of the method for preparing an ultra-thin metal foil with a carrier provided by an embodiment of the present invention, several embodiments and comparative examples are described below.

[0054] Example 1:

[0055] An ultra-thin copper foil with a carrier comprises a carrier foil, a metal release layer, an organic release layer and an ultra-thin copper foil stacked in sequence, and a preparation method thereof comprises the following steps:

[0056] 1) The carrier copper foil is polished, and then the surface of the copper foil is degreased and pickled with acetone, anhydrous ethanol, and 10 vol.% dilute sulfuric acid in sequence;

[0057] 2) Using the carrier copper foil treated in step 1) as the cathode and the ruthenium-iridium-titanium plate as the anode, immerse the carrier copper foil in a 45°C nickel electroplating solution for direct current electroplating to form a metal stripping layer. The electroplating current density is 5A / dm 2 , electrolysis time 75s; the nickel electrodeposition solution system is 150g / L nickel sulfate hexahydrate, 40g / L boric acid, and 20g / L chloride;

[0058] 3) immersing the carrier copper foil containing the metal release layer in step 2) into an organic release layer solution of adenine at a concentration of 10 g / L for adsorption, wherein sulfuric acid at a concentration of 150 g / L is added to the organic release layer solution and the temperature of the organic release layer solution is 20° C.; ultrasonic treatment is performed at an ultrasonic frequency of 100 kHz, an ultrasonic power of 150 W, and a dipping time of 120 seconds to form an organic release layer, thereby obtaining a composite release layer;

[0059] 4) The carrier copper foil containing the composite peeling layer in step 3) is immersed in a 25°C electroplating copper solution as the cathode, and a ruthenium-iridium-titanium plate is used as the anode to form an extremely thin copper foil by electroplating at a current density of 5A / dm 2 The electrolysis time is 200s, the electrolyte temperature is 25°C, and the plating solution system contains 50g / L copper, 80g / L sulfuric acid, 20ppm chloride, 20ppm hydroxyethyl cellulose, and 40ppm gelatin.

[0060] Example 2:

[0061] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that in step 3), the temperature of the organic release layer solution is 50°C.

[0062] Example 3:

[0063] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that in step 3), the concentration of adenine in the organic stripping layer solution is 5 g / L.

[0064] Example 4:

[0065] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that in step 3), the ultrasonic power is 120W.

[0066] Example 5:

[0067] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that in step 3), the ultrasonic power is 90W.

[0068] Example 6:

[0069] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that in step 3), the ultrasonic power is 30W.

[0070] Example 7:

[0071] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that in step 3), the ultrasonic frequency is 80 kHz.

[0072] Example 8:

[0073] The ultra-thin metal foil with a carrier in this embodiment is the same as that in embodiment 1, except that in step 3), the ultrasonic frequency is 20 kHz.

[0074] Comparative Example 1:

[0075] An ultra-thin copper foil with a carrier comprises a carrier foil, a metal peeling layer and an ultra-thin copper foil stacked in sequence, and a preparation method thereof comprises the following steps:

[0076] 1) The carrier copper foil is polished, and then the surface of the copper foil is degreased and pickled with acetone, anhydrous ethanol, and 10 vol.% dilute sulfuric acid in sequence;

[0077] 2) Using the carrier copper foil treated in step 1) as the cathode and the ruthenium-iridium-titanium plate as the anode, immerse the carrier copper foil in a 45°C nickel electroplating solution for direct current electroplating to form a metal stripping layer. The electroplating current density is 5A / dm 2 , electrolysis time 75s; the nickel electrodeposition solution system is 150g / L nickel sulfate hexahydrate, 40g / L boric acid, and 20g / L chloride;

[0078] 3) The carrier copper foil containing the metal stripping layer in step 2) is immersed in a 25°C electroplating copper solution as the cathode, and a ruthenium-iridium-titanium plate is used as the anode to form an extremely thin copper foil by electroplating at a current density of 5A / dm 2 The electrolysis time is 200s, the electrolyte temperature is 25°C, and the plating solution system contains 50g / L copper, 80g / L sulfuric acid, 20ppm chloride, 20ppm hydroxyethyl cellulose, and 40ppm gelatin.

[0079] Comparative Example 2:

[0080] An ultra-thin copper foil with a carrier comprises a carrier foil, a metal release layer, an organic release layer and an ultra-thin copper foil stacked in sequence, and a preparation method thereof comprises the following steps:

[0081] 1) The carrier copper foil is polished, and then the surface of the copper foil is degreased and pickled with acetone, anhydrous ethanol, and 10 vol.% dilute sulfuric acid in sequence;

[0082] 2) Using the carrier copper foil treated in step 1) as the cathode and the ruthenium-iridium-titanium plate as the anode, immerse the carrier copper foil in a 45°C nickel electroplating solution for direct current electroplating to form a metal stripping layer. The electroplating current density is 5A / dm 2 , electrolysis time 75s; the nickel electrodeposition solution system is 150g / L nickel sulfate hexahydrate, 40g / L boric acid, and 20g / L chloride;

[0083] 3) immersing the carrier copper foil containing the metal release layer in step 2) into an organic release layer solution of adenine at a concentration of 10 g / L for adsorption, wherein sulfuric acid at a concentration of 150 g / L is added to the organic release layer solution at a temperature of 20° C., thereby forming an organic release layer to obtain a composite release layer;

[0084] 4) The carrier copper foil containing the composite peeling layer in step 3) is immersed in a 25°C electroplating copper solution as the cathode, and a ruthenium-iridium-titanium plate is used as the anode to form an extremely thin copper foil by electroplating at a current density of 5A / dm 2 The electrolysis time is 200s, the electrolyte temperature is 25°C, and the plating solution system contains 50g / L copper, 80g / L sulfuric acid, 20ppm chloride, 20ppm hydroxyethyl cellulose, and 40ppm gelatin.

[0085] Peel strength testing and peel strength uniformity calculation were performed on the ultra-thin metal foils with carriers in Examples 1-8 and Comparative Examples 1-2. The ultra-thin metal foils with carriers to be tested were laminated onto a base film (25μm TPI film) (pressure transmission, holding stage: lamination temperature 220°C * duration 2 hours * pressure 25kg). Test strips were cut using a strip cutting machine. Ten test strips were cut from each set of test samples, each with a width of 15mm and a length of 150mm. The strips were stretched at a rate of 50mm / min. The peel strength between the ultra-thin metal foil and the carrier foil was measured and the average value was calculated. The upper limit of the variation rate was (maximum value - average value) / average value, and the lower limit of the variation rate was (minimum value - average value) / average value. The test data are shown in Table 1.

[0086] Table 1. Average peel strength and uniformity of peel strength of ultra-thin metal foils with carriers of Examples 1-8 and Comparative Examples 1-2.

[0087]

[0088] As can be seen from Table 1, by using the ultra-thin metal foil with a carrier and the preparation method thereof of the present invention, a composite peeling layer is formed and stable peeling is achieved, thereby solving the problem of uneven and inefficient organic peeling layer in the current preparation process of ultra-thin copper foil with a carrier, thereby ensuring the peeling stability of the organic peeling layer and improving production efficiency.

[0089] In summary, the ultra-thin metal foil with a carrier includes a carrier foil, a metal stripping layer, an organic stripping layer and an ultra-thin metal foil stacked in sequence. The metal stripping layer is prepared by electroplating on the surface of the surface-treated carrier foil, and the organic stripping layer solution is dip-coated on the surface of the metal stripping layer to form an organic stripping layer to prepare a composite stripping layer. The metal stripping layer forms a strong interface bond with the carrier foil, and the organic stripping layer forms a weak interface bond with the ultra-thin metal foil, thereby achieving differentiated control of the interface strength and enabling the ultra-thin metal foil to be stripped. At the same time, in the preparation process of the dip-coated organic stripping layer, ultrasonic treatment is introduced to promote the formation of the organic stripping layer, so that the organic stripping layer is formed faster, the film layer is thicker and more uniform, the production efficiency is high, the stripping stability can be improved, and the production efficiency can be increased.

[0090] 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.

[0091] 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. A method for preparing an ultra-thin metal foil with a carrier, characterized in that: The ultra-thin metal foil with a carrier comprises a carrier foil, a metal release layer, an organic release layer and an ultra-thin metal foil stacked in sequence. The preparation method of the ultra-thin metal foil with a carrier comprises the following steps: 1) forming a metal release layer by electrodeposition on a surface of a carrier foil; wherein the metal release layer comprises at least one element selected from the group consisting of chromium, nickel, cobalt, iron, copper, and titanium; 2) immersing the carrier foil containing the metal release layer in an organic release layer solution and performing ultrasonic treatment to form an organic release layer; 3) forming an ultra-thin metal foil on the surface of the organic release layer.

2. The method for preparing an ultra-thin metal foil with a carrier according to claim 1, wherein: Before the metal release layer is formed by electrodeposition in step 1), at least one side of the carrier foil is subjected to surface treatment, wherein the surface treatment includes at least one of polishing, deoxidation and degreasing.

3. The method for preparing an ultra-thin metal foil with a carrier according to claim 2, wherein: The surface treatment of the carrier foil is carried out by sequentially treating with acetone, anhydrous ethanol, and 10 vol.% dilute sulfuric acid.

4. The method for preparing an ultra-thin metal foil with a carrier according to claim 1, wherein: The metal stripping layer in step 1) is metal nickel.

5. The method for preparing an ultra-thin metal foil with a carrier according to claim 4, wherein: The electrolyte for the electroplating of metallic nickel includes nickel sulfate hexahydrate at a concentration of 50-300 g / L, boric acid at a concentration of 20-120 g / L, and chloride at a concentration of 20-120 g / L; the electrolyte temperature is 20-70° C., and the current density is 5-30 A / dm 2 , electrolysis time 10-200s.

6. The method for preparing an ultra-thin metal foil with a carrier according to claim 1, wherein: The organic stripping layer in step 2) comprises at least one substance selected from the group consisting of purine organic matter and derivatives of purine organic matter.

7. The method for preparing an ultra-thin metal foil with a carrier according to claim 6, wherein: The organic peeling layer includes at least one substance selected from adenine, guanine, xanthine, hypoxanthine, caffeine and theophylline.

8. The method for preparing an ultra-thin metal foil with a carrier according to claim 6, wherein: The concentration of the organic stripping layer is 0.1 g / L-10 g / L.

9. The method for preparing an ultra-thin metal foil with a carrier according to claim 1, wherein: The ultrasonic frequency of the ultrasonic treatment in step 2) is 10-150 kHz, the ultrasonic power is 10-150 W, and the dipping time is 10-3000 s.

10. The method for preparing an ultra-thin metal foil with a carrier according to claim 1, wherein: In step 2), the carrier foil containing the metal release layer is 2-20 cm away from the bottom of the organic release layer solution.

11. The method for preparing an ultra-thin metal foil with a carrier according to any one of claims 1 to 10, characterized in that: The ultra-thin metal foil in step 3) is an ultra-thin copper foil, which is formed by electrodeposition using an electrolyte having a copper concentration of 50-110 g / L, a sulfuric acid concentration of 80-120 g / L, a chloride concentration of 20-50 ppm, a hydroxyethyl cellulose concentration of ≤20 ppm, and a gelatin concentration of ≤40 ppm; the electrolyte temperature is 20-70°C, and the current density is 5-30 A / dm 2 , electrolysis time 10-200s.

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