Preparation method of ultra-thin copper foil with metal-organic disulfide as composite stripping layer

Abstract

The invention relates to a preparation method of an ultra-thin copper foil with metal-organic disulfide as a composite stripping layer, and belongs to the technical field of manufacturing of thin copper foils. The metal stripping layer is prepared through direct-current electrodeposition, and the interface of a carrier copper foil and the metal stripping layer is strongly combined; organic disulphide or organic disulphide salt is adsorbed between the metal stripping layer and the ultra-thin copper foil to form an organic stripping layer, so that a composite stripping layer with a uniform surface and stable performance is obtained, the stripping strength of the carrier copper foil is effectively reduced, and the ultra-thin copper foil is ultra-thin and uniform; and the binding force between the composite stripping layer and the carrier foil and the binding force between the composite stripping layer and the ultra-thin copper foil are different, so that the ultra-thin copper foil before and after pressing can be easily, completely and stably stripped from the carrier foil.

Description

Technical Field

[0001] The invention relates to a method for preparing an ultra-thin copper foil using a metal-organic disulfide composite peeling layer, and belongs to the technical field of manufacturing thin copper foil. Background Art

[0002] Electrolytic copper foil, a key foundational material, is widely used in modern technology, including chip packaging, printed circuit boards, and new energy devices. The trend toward higher-density integrated circuits and the growing demand for lightweight power batteries are placing higher demands on the thickness and performance of copper foil. The production of extremely thin copper foil presents numerous challenges, as thinner foil is easily affected by external forces, resulting in wrinkles and tears. To address these challenges, copper foil manufacturers and research institutions have begun using a carrier-attached method to produce ultra-thin copper foil. This method typically forms a release layer on the surface of the electrolytic copper foil, ultimately allowing for the deposition of an ultra-thin copper foil layer. The design and performance of the release layer are crucial for achieving effective separation between the carrier copper foil and the ultra-thin copper foil. Currently, peeling layers are mainly divided into three types: inorganic peeling layers, organic peeling layers, and composite peeling layers. Inorganic peeling layers are generally composed of metal layers or alloy layers. Their advantage is good stability at high temperatures, but diffusion between the metal layer and the copper foil may occur, enhancing the interfacial adhesion strength, resulting in difficulty in separation. Organic peeling layers use nitrogen-containing compounds or sulfur-containing compounds as materials. Their advantage is that separation is easy to achieve during the preparation process, but sometimes the peeling strength is insufficient, which affects the stability of extremely thin copper foil. To overcome these shortcomings, composite peeling layers combine the strengths of organic layers and alloy layers, can adjust the interface properties between the peeling layer and the copper foil, and effectively improve the controllability and stability of separation. In summary, the selection of a release layer is a critical step in producing high-quality, ultra-thin copper foil. Different types of release layers have their own advantages and disadvantages. Researchers and engineers must carefully consider specific application requirements and production conditions to optimally select the appropriate release layer type to ensure the quality and stability of copper foil products.

[0003] Using an organic layer and a metal layer as a composite release layer can achieve a better separation between the carrier copper foil and the ultra-thin copper foil. The metal layer is deposited by electrochemical deposition in a salt solution containing metal elements. Electrochemical deposition makes the thickness of the metal layer easier to control and the coating thickness more uniform. The efficiency of electrodeposition can be improved by controlling the current density.

[0004] Currently, nitrogen-containing organic compounds dominate the production of ultra-thin copper foil peeling layers, with imidazole and triazole compounds being the most widely used. Due to their excellent chemical stability and controllable peeling properties, there is a pressing need to develop new, chemically stable, and easily peelable alternatives to imidazole and triazole compounds. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for preparing an ultra-thin copper foil using a metal-organic disulfide composite peeling layer. Summary of the invention: The present invention uses direct current electrodeposition to prepare a pure metal or alloy layer as a component of the metal stripping layer, and uses an organic disulfide or organic disulfide salt as a component of the organic stripping layer, forming a metal-organic disulfide composite stripping layer. Its stripping performance is comparable to, or even better than, that of nitrogen-containing organic compounds, breaking through the technical barrier that traditional stripping layer materials are limited to nitrogen-containing compounds. The organic layer forms a weak interface bond with the ultra-thin copper foil, while the metal stripping layer forms a strong interface bond with the carrier foil, achieving differentiated control of the interface strength and having the significant characteristics of easy stripping and a pure interface. Unlike the currently mainstream nitrogen-containing organic compounds such as imidazoles and triazoles, the present invention is the first to use organic disulfide or an organic disulfide salt as a key component of the organic stripping layer. Experiments have shown that this new organic stripping layer exhibits superior stripping stability and lower peel strength compared to commonly used nitrogen-containing organic compounds in terms of stripping performance. This innovation not only provides a new material option for the production of ultra-thin copper foil, but also opens up a new direction for industry development. Detailed description of the invention: The technical solutions of the present invention are as follows: A method for preparing an ultra-thin copper foil with a metal-organic disulfide composite peeling layer comprises the following steps: (1) Using a carrier copper foil as a cathode and a ruthenium-iridium-titanium plate as an anode, a metal stripping layer is deposited on the pretreated cathode carrier copper foil by direct current electroplating to obtain a carrier copper foil having a metal stripping layer; (2) treating the carrier copper foil having the metal stripping layer with an organic disulfide solution or an organic disulfide salt solution to form an organic stripping layer adsorption layer on the metal stripping layer, thereby obtaining a carrier copper foil having a composite stripping layer; (3) The carrier copper foil with the composite peeling layer is immersed in a copper electroplating solution at 20-70°C as the cathode, and a ruthenium-iridium-titanium plate is used as the anode to electro-deposit copper to obtain an extremely thin copper foil on the composite peeling layer.

[0008] Preferably, according to the present invention, in step (1), the thickness of the carrier copper foil is 30-40 μm.

[0009] Preferably, according to the present invention, in step (1), the pretreatment of the carrier copper foil is: polishing the carrier copper foil, removing the oxide layer and degreasing the carrier copper foil, and the degreasing the oxide layer is performed by sequentially degreasing and pickling the surface of the copper foil with acetone, anhydrous ethanol, and 10 vol.% dilute sulfuric acid.

[0010] According to the present invention, preferably, in step (1), the metal stripping layer is a metal stripping layer of one of chromium, nickel, cobalt, iron, copper or titanium, or an alloy layer of two of chromium, nickel, cobalt, iron, copper or titanium.

[0011] According to the preferred embodiment of the present invention, in step (1), the metal stripping layer is a nickel layer, and the specific method of direct current electrodeposition of the metal stripping layer is as follows: The carrier copper foil and the ruthenium-iridium-titanium plate are immersed in a 20-70°C electroplated nickel layer solution for direct current electroplating to prepare a carrier copper foil with a metal stripping layer; the current density during the electroplating process is 5-30A / dm 2 The electrodeposition time is 10-200s, and the composition of the electrodeposited nickel layer solution is: nickel sulfate hexahydrate 50-300g / L, boric acid 20-120g / L, and chloride 20-120g / L.

[0012] According to the preferred embodiment of the present invention, in step (1), the metal stripping layer is a copper layer, and the specific method of direct current electrodeposition of the metal stripping layer is as follows: The carrier copper foil and the ruthenium-iridium-titanium plate are immersed in a 20-70°C electroplated copper layer solution for direct current electroplating to prepare a carrier copper foil with a metal stripping layer; the current density during the electroplating process is 5-30A / dm 2 The electrodeposition time is 10-200s, and the composition of the electrodeposited copper layer solution is: 100-400g / L of copper sulfate pentahydrate, 20-200g / L of 98% sulfuric acid, and 0.01-0.5g / L of sodium chloride.

[0013] According to the present invention, preferably, in step (2), the organic disulfide in the organic disulfide solution is dimethyl disulfide, diphenyl disulfide, cystine or sodium cystine, the concentration of the organic disulfide is 0.1 g / L-10 g / L, and the solvent is ethanol.

[0014] According to the preferred embodiment of the present invention, in step (2), the organic disulfide salt in the organic disulfide salt solution is sodium polydisulfide bis(propane disulfide) (C3H6S2O3Na), the organic disulfide salt concentration is 0.1 g / L-10 g / L, and the solvent is deionized water.

[0015] According to the present invention, preferably, in step (2), the treatment with an organic disulfide solution or an organic disulfide salt solution is as follows: The carrier copper foil with the metal peeling layer is immersed in an organic disulfide solution or an organic disulfide salt solution for immersion, or the organic disulfide solution or the organic disulfide salt solution is sprayed on the carrier copper foil with the metal peeling layer.

[0016] According to the preferred embodiment of the present invention, in step (2), the dipping or spraying temperature is 10-60° C. and the time is 30-350 s.

[0017] According to the preferred embodiment of the present invention, in step (3), the copper electroplating solution comprises: 50-110 g / L of copper sulfate pentahydrate, 80-120 g / L of 98% sulfuric acid, 20-50 ppm of chloride ions, ≤20 ppm of hydroxyethyl cellulose, and ≤40 ppm of bone glue.

[0018] According to the preferred embodiment of the present invention, in step (3), the current density during the electrodeposition process is 5-30A / dm 2 , the electrodeposition time is 10-200s.

[0019] An ultra-thin copper foil with a metal-organic disulfide composite peeling layer is prepared by the method.

[0020] An ultra-thin copper foil with a metal-organic disulfide composite peeling layer comprises a carrier copper foil layer, a composite peeling layer and an ultra-thin copper foil layer. The composite peeling layer comprises a metal peeling layer and an organic disulfide peeling layer.

[0021] The technical features and advantages of the present invention are as follows: The present invention provides a method for preparing an ultra-thin copper foil having a metal-organic disulfide composite stripping layer. The composite stripping layer is obtained by direct current electrodeposition and organic adsorption. The composite stripping layer is extremely thin, uniform, and environmentally friendly. The bonding forces between the composite stripping layer, the carrier foil, and the ultra-thin copper foil are different, enabling the ultra-thin copper foil to be easily and completely and stably stripped from the carrier foil before and after lamination. The metal stripping layer is prepared by direct current electrodeposition, and a strong bond is formed at the interface between the carrier copper foil and the metal stripping layer. In order to further prevent atomic diffusion between the metal stripping layer and the ultra-thin copper foil, thereby affecting the quality of the ultra-thin copper foil, an organic stripping layer is adsorbed between the metal stripping layer and the ultra-thin copper foil, so that the metal stripping layer forms a weaker interface bond with the ultra-thin copper foil, while the metal layer forms a stronger interface bond with the carrier foil, thereby achieving differentiated control of the interface strength and realizing an ultra-thin copper foil that is easy to strip. This invention pioneers the mechanism of using organic disulfides to form specific chemical adsorption with the metal stripping layer surface through disulfide bonds (SS) to prepare the organic stripping layer, breaking through the limitation of traditional nitrogen-containing organic compounds that only rely on nitrogen atoms (N) to interact with the metal surface, and provides a new molecular design idea for the development of new and efficient metal stripping agents. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a morphology image of the ultra-thin copper foil prepared on the composite peeling layer in Example 1 of the present invention; Figure 2 This is a diagram showing the peeling of the carrier copper foil and the ultra-thin copper foil in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described below by way of examples, but is not limited thereto.

[0024] Example 1: A method for preparing an ultra-thin copper foil with a metal-organic disulfide composite peeling layer, comprising the following steps: (1) The carrier copper foil is polished, deoxidized and degreased. In order to remove the grease and oxidation layer on the surface of the carrier copper foil, the carrier copper foil is pickled. Acetone, anhydrous ethanol and 10 vol.% dilute sulfuric acid are used to degrease and pickle the copper foil surface in sequence; The pretreated carrier copper foil was used as the cathode and the ruthenium-iridium-titanium plate was used as the anode. The cathode carrier copper foil was immersed in a 45°C electroplated nickel layer solution for direct current electrodeposition to prepare a carrier copper foil with a metal stripping layer. The current density during the electroplating process was 5A / dm 2 , electrodeposition time 75s; the composition of the electrodeposited nickel layer solution is: nickel sulfate hexahydrate 150g / L, boric acid 40g / L, chloride 20g / L; (2) Immersing the carrier copper foil with the metal stripping layer in a sodium polydisulfide dipropane sulfonate (C3H6S2O3Na) solution for adsorption to obtain a carrier copper foil with a composite stripping layer; the adsorption treatment temperature is 20°C, the time is 30s, and the concentration of sodium polydisulfide dipropane sulfonate (C3H6S2O3Na) in the sodium polydisulfide dipropane sulfonate (C3H6S2O3Na) solution is 10g / L; (3) The carrier copper foil with the composite peeling layer is immersed in a 25°C electroplating copper solution as the cathode, and the ruthenium-iridium-titanium plate is used as the anode for electroplating to obtain an extremely thin copper foil on the composite peeling layer; the current density during the electroplating process is 5A / dm 2 The electroplating time is 200s, and the composition of the electroplating copper solution is: 50g / L copper sulfate pentahydrate, 80g / L 98% sulfuric acid, 20ppm chloride ion, 20ppm hydroxyethyl cellulose; 40ppm bone glue.

[0025] The morphology of the ultra-thin copper foil obtained on the composite peeling layer is shown in Figure 1 ,Depend on Figure 1 It can be seen that the layers are distinct, with the ultra-thin copper foil on the upper side of the carrier copper foil and a clear boundary between the two, making them easy to separate. That is, the composite peeling layer can effectively separate the carrier copper foil from the ultra-thin copper foil. Figure 2 Schematic diagram of actual peeling of the carrier copper foil and the ultra-thin copper foil in the ultra-thin carrier copper foil of the present invention. It can be seen that the ultra-thin copper foil can be easily peeled off from the carrier copper foil.

[0026] Example 2: The same preparation method as described in Example 1, except that: In step (2), the concentration of sodium disulfide bis(propylene disulfide) (C3H6S2O3Na) in the sodium disulfide bis(propylene disulfide) (C3H6S2O3Na) solution is 5 g / L, and the rest is carried out as in Example 1.

[0027] Example 3: The same preparation method as described in Example 1, except that: In step (2), the concentration of sodium disulfide bis(propane disulfide) sodium sulfonate (C3H6S2O3Na) in the sodium disulfide bis(propane disulfide) sodium sulfonate (C3H6S2O3Na) solution is 1 g / L, and the rest is carried out as in Example 1.

[0028] Example 4: The same preparation method as described in Example 1, except that: In step (1), the electrolyte temperature is 45° C., the electrolysis time is 75 s, and the rest is carried out as in Example 1.

[0029] Example 5: The same preparation method as described in Example 1, except that: In step (1), the pretreated carrier copper foil is used as the cathode and the ruthenium-iridium-titanium plate is used as the anode. The cathode carrier copper foil is immersed in a 45°C electroplated copper layer solution to perform direct current electroplating to prepare a carrier copper foil with a metal stripping layer; the current density during the electroplating process is 5A / dm 2 , electrodeposition time 75s; the concentration of copper sulfate pentahydrate in the electrodeposition copper solution is 200g / L, 98% sulfuric acid is 100g / L, and sodium chloride is 0.02g / L; other steps are carried out as in Example 1.

[0030] Comparative Example 1: The method is the same as that described in Example 1, except that: (1) The carrier copper foil is polished, deoxidized and degreased. In order to remove the grease and oxidation layer on the surface of the carrier copper foil, the carrier copper foil is pickled. Acetone, anhydrous ethanol and 10 vol.% dilute sulfuric acid are used to degrease and pickle the copper foil surface in sequence; The pretreated carrier copper foil was used as the cathode and the ruthenium-iridium-titanium plate was used as the anode. The cathode carrier copper foil was immersed in a 45°C electroplated nickel layer solution for direct current electrodeposition to prepare a carrier copper foil with a metal stripping layer. The current density during the electroplating process was 5A / dm 2 , electrodeposition time 75s; nickel sulfate hexahydrate concentration in the electrodeposition nickel solution is 150g / L, boric acid concentration is 40g / L, and chloride concentration is 20g / L; (2) The carrier copper foil with the metal stripping layer is immersed in a 25°C copper electroplating solution as the cathode, and the ruthenium-iridium-titanium plate is used as the anode for electroplating to obtain an extremely thin copper foil on the carrier copper foil with the metal stripping layer; the current density during the electroplating process is 5A / dm 2 The electrolysis time is 200s, and the composition of the copper electroplating solution is: 50g / L copper sulfate pentahydrate, 80g / L 98% sulfuric acid, 20ppm chloride ion, 20ppm hydroxyethyl cellulose; 40ppm bone glue.

[0031] The peeling layer of the ultra-thin carrier copper foil prepared in Comparative Example 1 is composed of only a single metal layer. Compared with the composite peeling layer prepared in the embodiment of the present invention, the ultra-thin carrier copper foil in Comparative Example 1 has poor high temperature and heat resistance, and has a large peeling force, so the ultra-thin copper foil is not easily peeled off from the carrier copper foil.

[0032] Comparative Example 2: The same preparation method as described in Example 1, except that: In step (2), the sulfur-containing organic compound sodium polydisulfide dipropane sulfonate (C3H6S2O3Na) is replaced by benzimidazole, and the rest is carried out as in Example 1.

[0033] The organic layer is an imidazole compound commonly used in nitrogen-containing organic matter in the preparation process of the organic peeling layer. The peeling strength between the ultra-thin copper foil and the carrier copper foil is similar to the peeling strength of the peeling layer prepared from the sulfur-containing organic matter polydisulfide dipropylene sulfonate sodium (C3H6S2O3Na) of the present invention.

[0034] Experimental example The concentration of sodium polydipropylene disulfide sulfonate (C3H6S2O3Na) in Example 1 was varied to 1.5 g / L, 3 g / L, 5 g / L, and 10 g / L, respectively, to obtain an extremely thin copper foil on the composite peeling layer. The peel strengths before and after lamination were compared, as shown in Table 1.

[0035] Table 1 Peel strength before and after lamination

[0036] It can be seen from Table 1 that the concentration of the organic disulfide salt, sodium polydisulfide bis(propane disulfide) (C3H6S2O3Na), has almost no effect on the peel strength of the ultra-thin carrier copper foil, indicating that the organic disulfide salt, sodium polydisulfide bis(propane disulfide) (C3H6S2O3Na), has stable performance in the peel strength preparation of the ultra-thin copper foil.

Claims

1. A method for preparing an ultra-thin copper foil with a metal-organic disulfide composite peeling layer, characterized in that: The steps are as follows: (1) Using a carrier copper foil as a cathode and a ruthenium-iridium-titanium plate as an anode, a metal stripping layer is deposited on the pretreated cathode carrier copper foil by direct current electroplating to obtain a carrier copper foil having a metal stripping layer; (2) treating the carrier copper foil having the metal stripping layer with an organic disulfide solution or an organic disulfide salt solution to form an organic stripping layer adsorption layer on the metal stripping layer, thereby obtaining a carrier copper foil having a composite stripping layer; (3) The carrier copper foil with the composite peeling layer is immersed in a copper electroplating solution at 20-70°C as the cathode, and a ruthenium-iridium-titanium plate is used as the anode to electro-deposit copper to obtain an extremely thin copper foil on the composite peeling layer.

2. The preparation method according to claim 1, characterized in that In step (1), the thickness of the carrier copper foil is 30-40 μm, and the pretreatment of the carrier copper foil is as follows: polishing the carrier copper foil and removing the oxide layer and oil stains. The oxide layer and oil stains removal treatment is to use acetone, anhydrous ethanol, and 10 vol.% dilute sulfuric acid to sequentially remove grease and pickle the surface of the copper foil.

3. The preparation method according to claim 1, characterized in that In step (1), the metal stripping layer is a metal stripping layer of one of chromium, nickel, cobalt, iron, copper or titanium, or an alloy layer of two of chromium, nickel, cobalt, iron, copper or titanium.

4. The preparation method according to claim 3, characterized in that In step (1), the metal stripping layer is a nickel layer, and the specific method of direct current electrodeposition of the metal stripping layer is as follows: The carrier copper foil and the ruthenium-iridium-titanium plate are immersed in a 20-70°C electroplated nickel layer solution for direct current electroplating to prepare a carrier copper foil with a metal stripping layer; the current density during the electroplating process is 5-30A / dm 2 , the electrodeposition time is 10-200s, and the composition of the electrodeposited nickel layer solution is: nickel sulfate hexahydrate 50-300g / L, boric acid 20-120g / L, chloride 20-120g / L; In step (1), the metal stripping layer is a copper layer, and the specific method of direct current electrodeposition of the metal stripping layer is as follows: The carrier copper foil and the ruthenium-iridium-titanium plate are immersed in a 20-70°C electroplated copper layer solution for direct current electroplating to prepare a carrier copper foil with a metal stripping layer; the current density during the electroplating process is 5-30A / dm 2 The electrodeposition time is 10-200s, and the composition of the electrodeposited copper layer solution is: 100-400g / L of copper sulfate pentahydrate, 20-200g / L of 98% sulfuric acid, and 0.01-0.5g / L of sodium chloride.

5. The preparation method according to claim 1, characterized in that In step (2), the organic disulfide in the organic disulfide solution is dimethyl disulfide, diphenyl disulfide, cystine or sodium cystine, the organic disulfide concentration is 0.1 g / L-10 g / L, the solvent is ethanol, the organic disulfide salt in the organic disulfide salt solution is sodium polydisulfide dipropane sulfonate (C3H6S2O3Na), the organic disulfide salt concentration is 0.1 g / L-10 g / L, and the solvent is deionized water.

6. The preparation method according to claim 3, characterized in that In step (2), the organic disulfide solution or organic disulfide salt solution is used for treatment: The carrier copper foil with the metal peeling layer is immersed in an organic disulfide solution or an organic disulfide salt solution for immersion, or the organic disulfide solution or the organic disulfide salt solution is sprayed on the carrier copper foil with the metal peeling layer.

7. The preparation method according to claim 6, characterized in that In step (2), the dipping or spraying temperature is 10-60°C and the time is 30-350s.

8. The preparation method according to claim 3, characterized in that In step (3), the copper electroplating solution comprises: 50-110 g / L of copper sulfate pentahydrate, 80-120 g / L of 98% sulfuric acid, 20-50 ppm of chloride ion, ≤20 ppm of hydroxyethyl cellulose, and ≤40 ppm of bone glue.

9. The preparation method according to claim 3, characterized in that In step (3), the current density during the electrodeposition process is 5-30A / dm 2 , the electrodeposition time is 10-200s.

10. An ultra-thin copper foil with a metal-organic disulfide composite peeling layer, characterized in that: The method is prepared by any one of claims 1 to 9.

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