A method for preparing an extremely thin copper foil with a metal-organic disulfide as a composite exfoliation layer

Abstract

The present application relates to a kind of preparation method of extremely thin copper foil with metal-organic disulfide as composite stripping layer, belong to the manufacturing technical field of thin thickness copper foil, the present application uses direct current deposition to prepare metal stripping layer, the interface of carrier copper foil and metal stripping layer is stronger combined, then organic disulfide or organic disulfide salt is adsorbed between metal stripping layer and extremely thin copper foil, form organic stripping layer, obtain the composite stripping layer of surface uniformity, stable performance, effectively reduce the stripping strength of carrier copper foil, extremely thin copper foil is extremely thin and uniform, and the bonding force between composite stripping layer and carrier foil and extremely thin copper foil is different, can make the extremely thin copper foil before and after pressing be easily completely, stably and with carrier foil stripping.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing an ultra-thin copper foil with a metal-organic disulfide composite release layer, belonging to the technical field of thin copper foil manufacturing. BACKGROUND

[0002] Electrolytic copper foil, as a key basic material, is widely used in modern technology fields, including chip packaging, printed circuit boards, and new energy equipment. With the development of integrated circuits towards high density, and the increasing demand for lightweight power batteries, higher requirements are placed on the thickness and performance of copper foil. Especially in the preparation of ultra-thin copper foil, there are many challenges, because thinner copper foil is easily affected by external forces, causing wrinkles, tears, and other problems.

[0003] To address these challenges, copper foil enterprises and research institutions have begun to use the carrier method to prepare ultra-thin copper foil. This method usually forms a release layer on the surface of the electrolytic copper foil to finally deposit an ultra-thin copper foil layer. The design and performance of the release layer are crucial for effective separation between the carrier copper foil and the ultra-thin copper foil.

[0004] Currently, the release layer is mainly divided into three types: inorganic release layer, organic release layer, and composite release layer. The inorganic release layer is generally composed of a metal layer or an alloy layer, which has the advantage of good stability at high temperatures, but may cause diffusion between the metal layer and the copper foil, enhancing the interfacial adhesion strength and leading to difficulty in separation. The organic release layer uses nitrogen-containing compounds or sulfur-containing compounds as materials, which has the advantage of easy separation during preparation, but sometimes the release strength is insufficient, which may affect the stability of the ultra-thin copper foil. To overcome these defects, the composite release layer combines the advantages of organic layers and alloy layers, and can adjust the interfacial properties between the release layer and the copper foil, effectively improving the controllability and stability of separation.

[0005] In summary, the selection of the release layer is a key step in the preparation of high-quality ultra-thin copper foil. Different types of release layers have their own advantages and disadvantages, and researchers and engineers need to consider the specific application requirements and preparation conditions to reasonably select the type of release layer, thereby ensuring the quality and stability of the copper foil product.

[0006] Using an organic layer and a metal layer as a composite release layer can achieve better separation between the carrier copper foil and the ultra-thin copper foil, where the metal layer is obtained by electrochemical deposition in a salt solution containing metal elements. The electrochemical deposition method can make the thickness of the metal layer more easily controlled and the plating thickness more uniform, and by controlling the current density, the efficiency of electro-deposition can be improved.

[0007] Currently, nitrogen-containing organic compounds dominate the production of ultra-thin copper foil release layers, with imidazole and triazole compounds being the most widely used. Due to their excellent chemical stability and controllable release properties, there is an urgent need to develop new organic compounds with superior chemical stability and easy release properties to replace imidazole and triazole compounds. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a method for preparing an ultrathin copper foil with a metal-organic disulfide composite release layer. Invention Overview:

[0010] This invention employs direct current electrodeposition to prepare a pure metal or alloy layer as the metal release layer component, and uses organic disulfides or organic disulfide salts as the organic release layer component, forming a metal-organic disulfide composite release layer. Its release performance is comparable to, or even superior to, nitrogen-containing organic materials, breaking through the technical barrier of traditional release layer materials being limited to nitrogen-containing compounds. The organic layer forms a weak interfacial bond with the ultra-thin copper foil, while the metal release layer forms a strong interfacial bond with the carrier foil, achieving differentiated control of interfacial strength. It features easy release and a pure interface. Unlike the currently mainstream imidazole and triazole nitrogen-containing organic materials, this invention is the first to use organic disulfides or organic disulfide salts as the key component of the organic release layer. Experiments show that this novel organic release layer exhibits superior release stability and lower release strength compared to commonly used nitrogen-containing organic materials. This innovation not only provides a completely new material option for the production of ultra-thin copper foil but also opens up new directions for industry development. Invention Details:

[0012] The technical solution of the present invention is as follows:

[0013] A method for preparing an ultrathin copper foil with a metal-organic disulfide composite release layer includes the following steps:

[0014] (1) Using a carrier copper foil as the cathode and a ruthenium-iridium-titanium plate as the anode, a metal release layer is deposited on the pretreated cathode carrier copper foil by direct current electrodeposition to obtain a carrier copper foil with a metal release layer.

[0015] (2) The carrier copper foil with the metal stripping layer is treated 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 with a composite stripping layer.

[0016] (3) The carrier copper foil with composite release layer is used as the cathode and immersed in the copper plating solution at 20-70℃. A ruthenium-iridium-titanium plate is used as the anode to perform copper electrodeposition, and an extremely thin copper foil is obtained on the composite release layer.

[0017] According to a preferred embodiment of the present invention, in step (1), the thickness of the carrier copper foil is 30-40 μm.

[0018] According to a preferred embodiment of the present invention, in step (1), the pretreatment of the carrier copper foil is as follows: polishing the carrier copper foil, removing the oxide layer and removing oil stains, wherein the oxide layer and removing oil stains are performed by sequentially applying acetone, anhydrous ethanol and 10 vol.% dilute sulfuric acid to the surface of the copper foil to remove grease and pickling.

[0019] According to a preferred embodiment of the present invention, in step (1), the metal stripping layer is one of chromium, nickel, cobalt, iron, copper or titanium, or an alloy layer of two of chromium, nickel, cobalt, iron, copper or titanium.

[0020] According to a preferred embodiment of the present invention, in step (1), the metal stripping layer is a nickel layer, and the specific method for direct current electrodeposition of the metal stripping layer is as follows:

[0021] A copper foil carrier and a ruthenium-iridium-titanium plate were immersed in a nickel electrodeposition solution at 20-70℃ for direct current electrodeposition to prepare a copper foil carrier with a metal release layer; the current density during the electrodeposition process was 5-30 A / dm³. 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.

[0022] According to a preferred embodiment of the present invention, in step (1), the metal stripping layer is a copper layer, and the specific method for direct current electrodeposition of the metal stripping layer is as follows:

[0023] A copper foil carrier with a metal release layer is prepared by immersing a copper foil carrier and a ruthenium-iridium-titanium plate in a copper deposition solution at 20-70℃ using direct current electrodeposition; the current density during the electrodeposition process is 5-30 A / dm³. 2 The electrodeposition time is 10-200s, and the composition of the copper electrodeposition solution is: 100-400g / L copper sulfate pentahydrate, 20-200g / L sulfuric acid with a mass concentration of 98%, and 0.01-0.5g / L sodium chloride.

[0024] According to a preferred embodiment of the present invention, 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.

[0025] According to a preferred embodiment of the present invention, in step (2), the organic disulfide salt in the organic disulfide salt solution is sodium polydisulfide dipropane sulfonate (C3H6S2O3Na), the concentration of the organic disulfide salt is 0.1g / L-10g / L, and the solvent is deionized water.

[0026] According to a preferred embodiment of the present invention, in step (2), the treatment using an organic disulfide solution or an organic disulfide salt solution is as follows:

[0027] The carrier copper foil with a metal release layer is immersed in an organic disulfide solution or an organic disulfide salt solution for impregnation, or the carrier copper foil with a metal release layer is sprayed with an organic disulfide solution or an organic disulfide salt solution.

[0028] According to a preferred embodiment of the present invention, in step (2), the immersion or spraying temperature is 10-60°C and the time is 30-350s.

[0029] According to a preferred embodiment of the present invention, in step (3), the composition of the electroplating copper solution is: copper sulfate pentahydrate 50-110 g / L, 98% sulfuric acid 80-120 g / L, chloride ions 20-50 ppm, hydroxyethyl cellulose ≤20 ppm; bone glue ≤40 ppm.

[0030] According to a preferred embodiment of the present invention, in step (3), the current density during the electrodeposition process is 5-30 A / dm². 2 The electrodeposition time is 10-200s.

[0031] An ultrathin copper foil with a metal-organic disulfide composite release layer was prepared by the above method.

[0032] An ultrathin copper foil with a metal-organic disulfide composite release layer includes a carrier copper foil layer, a composite release layer, and an ultrathin copper foil layer. The composite release layer includes a metal release layer and an organic disulfide release layer.

[0033] Technical features and advantages of the present invention:

[0034] This invention provides a method for preparing an ultrathin copper foil with a metal-organic disulfide composite release layer. The composite release layer is obtained through direct current electrodeposition and organic adsorption. This composite release layer is extremely thin, uniform, and environmentally friendly. Furthermore, the bonding strength between the composite release layer and the carrier foil, as well as the ultrathin copper foil, varies, enabling the ultrathin copper foil to be easily and completely peeled off from the carrier foil before and after lamination. The metal release layer is prepared by direct current electrodeposition, resulting in a strong bond between the carrier copper foil and the metal release layer. To further prevent atomic diffusion between the metal release layer and the ultrathin copper foil, which could affect the quality of the ultrathin copper foil, an organic release layer is adsorbed between the metal release layer and the ultrathin copper foil. This results in a weaker interfacial bond between the metal release layer and the ultrathin copper foil, while the metal layer and the carrier foil form a stronger interfacial bond. This allows for differentiated control of the interfacial strength, achieving easily peelable ultrathin copper foil. This invention innovatively utilizes the mechanism by which organic disulfides form specific chemical adsorption with the surface of the metal stripping layer through disulfide bonds (SS) to prepare the organic stripping layer. This breaks through the limitation of traditional nitrogen-containing organic compounds relying solely on the interaction between nitrogen atoms (N) and the metal surface, and provides a completely new molecular design approach for the development of novel and efficient metal stripping agents. Attached Figure Description

[0035] Figure 1 This is a morphological image of the ultrathin copper foil prepared on the composite release layer in Embodiment 1 of the present invention;

[0036] Figure 2 This is a diagram showing the peeling of the carrier copper foil and the ultra-thin copper foil in Embodiment 1 of the present invention. Detailed Implementation

[0037] The present invention will be further illustrated by the following embodiments, but is not limited thereto.

[0038] Example 1:

[0039] A method for preparing an ultrathin copper foil with a metal-organic disulfide composite release layer, comprising the following steps:

[0040] (1) The carrier copper foil is polished, deoxidized and degreased. In order to remove the grease and oxide 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.

[0041] Using pretreated copper foil as the cathode and a ruthenium-iridium-titanium plate as the anode, the copper foil was immersed in a 45°C nickel electrodeposition solution for direct current electrodeposition to prepare a copper foil with a metal release layer; the current density during the electrodeposition process was 5 A / dm³. 2The electrodeposition time was 75 s; the composition of the electrodeposition nickel layer solution was: nickel sulfate hexahydrate 150 g / L, boric acid 40 g / L, chloride 20 g / L;

[0042] (2) The carrier copper foil with the metal release layer is immersed in the sodium polydisulfide dipropane sulfonate (C3H6S2O3Na) solution for adsorption to obtain the carrier copper foil with the composite release layer; the adsorption treatment temperature is 20℃, the time is 30s, and the concentration of sodium polydisulfide dipropane sulfonate (C3H6S2O3Na) in the sodium polydisulfide dipropane sulfonate (C3H6S2O3Na) solution is 10g / L;

[0043] (3) The carrier copper foil with the composite release layer is used as the cathode and immersed in the copper plating solution at 25°C. A ruthenium-iridium-titanium plate is used as the anode for electrodeposition to obtain an extremely thin copper foil on the composite release layer. The current density during the electrodeposition process is 5A / dm³. 2 The electrodeposition time was 200s, and the composition of the copper plating solution was: 50g / L copper sulfate pentahydrate, 80g / L 98% sulfuric acid, 20ppm chloride ions, 20ppm hydroxyethyl cellulose, and 40ppm bone glue.

[0044] The morphology of the ultrathin copper foil obtained on the composite release layer is shown in the figure. Figure 1 ,Depend on Figure 1 It can be seen that the layers are distinct, with the ultrathin copper foil on the upper side of the carrier copper foil and the boundary between the two is clear and easy to separate. That is, the composite stripping layer can effectively separate the carrier copper foil and the ultrathin copper foil. Figure 2 This is a schematic diagram of the 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.

[0045] Example 2:

[0046] The preparation method is the same as that described in Example 1, except that:

[0047] In step (2), the concentration of sodium didisulfide dipropane sulfonate (C3H6S2O3Na) in the sodium didisulfide dipropane sulfonate (C3H6S2O3Na) solution is 5 g / L, and the rest is carried out according to Example 1.

[0048] Example 3:

[0049] The preparation method is the same as that described in Example 1, except that:

[0050] In step (2), the concentration of sodium didisulfide dipropane sulfonate (C3H6S2O3Na) in the sodium didisulfide dipropane sulfonate (C3H6S2O3Na) solution is 1 g / L, and the rest is carried out according to Example 1.

[0051] Example 4:

[0052] The preparation method is the same as that described in Example 1, except that:

[0053] In step (1), the electrolyte temperature is 45°C and the electrolysis time is 75s. Other steps are carried out as in Example 1.

[0054] Example 5:

[0055] The preparation method is the same as that described in Example 1, except that:

[0056] In step (1), a pretreated carrier copper foil is used as the cathode, and a ruthenium-iridium-titanium plate is used as the anode. The cathode carrier copper foil is immersed in a copper layer electrodeposition solution at 45°C for direct current electrodeposition to prepare a carrier copper foil with a metal release layer. The current density during the electrodeposition process is 5 A / dm³. 2 The electrodeposition time was 75 s; the concentration of copper sulfate pentahydrate in the electrodeposition copper solution was 200 g / L, 98% sulfuric acid was 100 g / L, and sodium chloride was 0.02 g / L; other procedures were carried out as in Example 1.

[0057] Comparative Example 1:

[0058] The method described in the same way as in Example 1 differs in that:

[0059] (1) The carrier copper foil is polished, deoxidized and degreased. In order to remove the grease and oxide 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.

[0060] Using pretreated copper foil as the cathode and a ruthenium-iridium-titanium plate as the anode, the copper foil was immersed in a 45°C nickel electrodeposition solution for direct current electrodeposition to prepare a copper foil with a metal release layer; the current density during the electrodeposition process was 5 A / dm³. 2 The electrodeposition time was 75 s; the concentration of nickel sulfate hexahydrate in the electrodeposition nickel solution was 150 g / L, the concentration of boric acid was 40 g / L, and the concentration of chloride was 20 g / L.

[0061] (2) A copper foil with a metal stripping layer is used as the cathode and immersed in a copper plating solution at 25°C. A ruthenium-iridium-titanium plate is used as the anode for electrodeposition to obtain an extremely thin copper foil on the copper foil with the metal stripping layer. The current density during the electrodeposition process is 5 A / dm³. 2 The electrolysis time is 200s. The composition of the copper plating solution is: 50g / L copper sulfate pentahydrate, 80g / L 98% sulfuric acid, 20ppm chloride ions, 20ppm hydroxyethyl cellulose, and 40ppm bone glue.

[0062] The release layer of the ultra-thin carrier copper foil prepared in Comparative Example 1 consists of only a single metal layer. Compared with the composite release layer prepared in the embodiment of the present invention, the ultra-thin carrier copper foil in Comparative Example 1 has poor high temperature resistance and heat resistance, and has a large peeling force, making it difficult for the ultra-thin copper foil to peel off from the carrier copper foil.

[0063] Comparative Example 2:

[0064] The preparation method is the same as that described in Example 1, except that:

[0065] In step (2), benzimidazole is used to replace sodium polydisulfide dipropane sulfonate (C3H6S2O3Na), and the rest is carried out as in Example 1.

[0066] The organic layer is an imidazole compound commonly used in the preparation of nitrogen-containing organic materials during the organic release layer process. The peel strength between the extremely thin copper foil and the carrier copper foil is similar to the peel strength of the release layer prepared by the sulfur-containing organic material sodium polydisulfide dipropane sulfonate (C3H6S2O3Na) of this invention.

[0067] Experimental Example

[0068] The concentration of sodium polydisulfide dipropane sulfonate (C3H6S2O3Na) in Example 1 was changed to 1.5 g / L, 3 g / L, 5 g / L and 10 g / L, respectively, and extremely thin copper foils were obtained on the composite release layer. The peel strength before and after pressing was compared, as shown in Table 1.

[0069] Table 1 Peel strength before and after pressing

[0070]

[0071] As can be seen from Table 1, the concentration of the organic disulfide salt, sodium polydisulfide dipropane sulfonate (C3H6S2O3Na), has almost no effect on the peel strength of the ultra-thin carrier copper foil, indicating that the organic disulfide salt, sodium polydisulfide dipropane sulfonate (C3H6S2O3Na), has stable performance in peel strength for the preparation of ultra-thin copper foil.

Claims

1. A method for preparing an ultrathin copper foil with a metal-organic disulfide composite release layer, characterized in that, The steps include the following: (1) Using a carrier copper foil as the cathode and a ruthenium-iridium-titanium plate as the anode, a metal release layer is deposited on the pretreated cathode carrier copper foil by direct current electrodeposition to obtain a carrier copper foil with a metal release layer. (2) The carrier copper foil with the metal stripping layer is treated 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 with a composite stripping layer. 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. The organic disulfide salt in the organic disulfide salt solution is sodium polydisulfide dipropane sulfonate (C3H6S2O3Na), the concentration of the organic disulfide salt is 0.1 g / L-10 g / L, and the solvent is deionized water. Treatment with organic disulfide solutions or organic disulfide salt solutions is as follows: The carrier copper foil with the metal release layer is immersed in an organic disulfide solution or an organic disulfide salt solution for impregnation, or the carrier copper foil with the metal release layer is sprayed with an organic disulfide solution or an organic disulfide salt solution. In step (2), the immersion or spraying temperature is 10-60℃ and the time is 30-350s; (3) The carrier copper foil with the composite release layer is immersed in the copper plating solution at 20-70℃ as the cathode, and copper is electrodeposited using a ruthenium-iridium titanium plate as the anode to obtain an extremely thin copper foil on the composite release layer. Composition of copper plating solution: copper sulfate pentahydrate 50-110g / L, 98% sulfuric acid 80-120g / L, chloride ions 20-50ppm, hydroxyethyl cellulose ≤20ppm; bone glue ≤40ppm; The current density during electrodeposition is 5-30 A / dm2, and the electrodeposition time is 10-200 s.

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

3. The preparation method according to claim 1, characterized in that, In step (1), the metal stripping layer is 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 for direct current electrodeposition of the metal stripping layer is as follows: A copper foil carrier and a ruthenium-iridium-titanium plate are immersed in an electrodeposition nickel layer solution at 20-70℃ for direct current electrodeposition to prepare a copper foil carrier with a metal release layer. The current density during the electrodeposition process is 5-30 A / dm2, the electrodeposition time is 10-200 s, and the composition of the electrodeposition nickel layer solution is: nickel sulfate hexahydrate 50-300 g / L, boric acid 20-120 g / L, and chloride 20-120 g / L. In step (1), the metal stripping layer is a copper layer, and the specific method for direct current electrodeposition of the metal stripping layer is as follows: A copper foil carrier and a ruthenium-iridium-titanium plate are immersed in an electrodeposition copper layer solution at 20-70℃ to prepare a copper foil carrier with a metal release layer by direct current electrodeposition. The current density during the electrodeposition process is 5-30 A / dm2, the electrodeposition time is 10-200 s, and the composition of the electrodeposition copper layer solution is: 100-400 g / L copper sulfate pentahydrate, 20-200 g / L sulfuric acid with a mass concentration of 98%, and 0.01-0.5 g / L sodium chloride.

5. An ultrathin copper foil with a metal-organic disulfide composite release layer, characterized in that, It is prepared by any of the methods described in claims 1-4.

Images