Preparation method of ultra-thin copper foil with carrier

Abstract

The invention discloses a preparation method of an ultra-thin copper foil with a carrier, and belongs to the technical field of copper foil manufacturing. The method comprises the steps that S1, a titanium plate is adopted as a cathode, an iridium-plated titanium plate is adopted as an anode, the washed titanium plate is immersed in a copper electroplating solution at the temperature of 30-70 DEG C, and after electro-deposition is conducted, a carrier copper foil is prepared; s2, immersing the carrier copper foil prepared in the step S1 into an organic solution containing ionic liquid for adsorption to obtain a carrier copper foil with a stripping layer; and S3, taking the carrier copper foil with the stripping layer prepared in the step S2 as a cathode, carrying out water washing treatment, then immersing the carrier copper foil into another copper electroplating solution at the temperature of 30-70 DEG C, and carrying out electro-deposition by taking an iridium-plated titanium plate as an anode, so as to prepare the ultra-thin copper foil. The ultrathin and uniform single organic stripping layer is prepared in an organic adsorption mode, the method is simple in preparation process, and the stripping layer enables the ultrathin copper foil to be stably and completely stripped from the carrier copper foil by regulating and controlling the binding force between the carrier copper foil and the ultrathin copper foil.

Description

Technical Field

[0001] The present invention relates to the technical field of copper foil manufacturing, and particularly relates to a method for preparing a carrier-attached ultra-thin copper foil. Background Art

[0002] Electrolytic copper foils are widely used in high-tech fields such as printed circuit boards (PCBs), chip packaging, and new energy. With the continuous development of PCBs towards being thinner, denser, flatter, and chip packaging technologies, the requirements for the performance and thickness of electrolytic copper foils are getting higher and higher. However, during the production and application of ultra-thin copper foils, due to the small thickness of the ultra-thin copper foils, wrinkling and tearing are likely to occur. To solve this problem, relevant researchers have proposed the solution of carrier-attached ultra-thin copper foils. This method uses a conductive material with a certain thickness as a carrier, electro-deposits an ultra-thin copper foil on the carrier, and adds a release layer between the carrier copper foil and the ultra-thin copper foil, so that the ultra-thin copper foil can be well peeled off from the carrier.

[0003] Currently, release layers are mainly divided into three categories: inorganic release layers, organic release layers, and composite release layers. In the application of inorganic release layers, if a single metal layer is used, there is often a strong bonding force between it and the ultra-thin copper foil. This characteristic leads to metal residue on the ultra-thin copper foil after high-temperature lamination, which has an adverse effect on the subsequent application of the ultra-thin copper foil and may even cause the ultra-thin copper foil to not be smoothly peeled off from the carrier in severe cases. In the use of organic release layers, when a single organic layer is used, due to its low bonding strength, the ultra-thin copper foil is likely to fall off from the carrier during the preparation process of the ultra-thin copper foil.

[0004] Although the organic-inorganic composite release layer can effectively solve many problems faced by a single release layer, this technology has obvious limitations. On the one hand, its process flow is cumbersome and the uniformity problem of inorganic layer electroplating needs to be considered; on the other hand, the adsorption of the organic release layer to the inorganic layer must also be taken into account. To sum up, in the prior art, there are problems that the peeling strength between the release layer on the carrier copper foil and the interface of the ultra-thin copper foil is difficult to accurately control, and the process flow is complex.

[0005] Therefore, it is necessary to provide a method for preparing a carrier-attached ultra-thin copper foil. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing a carrier-attached ultra-thin copper foil to solve the problems in the prior art that the peeling strength between the release layer on the carrier copper foil and the interface of the ultra-thin copper foil is difficult to control, and the process flow is complex.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A method for preparing a carrier-attached ultra-thin copper foil includes the following steps:

[0009] S1, Preparation of the carrier copper foil

[0010] Using a titanium plate as the cathode and an iridium-coated titanium plate as the anode, immerse the washed titanium plate in an electroplating copper solution at 30 - 70°C, and after electro-deposition, obtain the carrier copper foil; perform a water washing treatment on the carrier copper foil;

[0011] S2, Preparation of the release layer

[0012] Immerse the carrier copper foil obtained in step S1 in an organic solution containing an ionic liquid for adsorption to obtain a carrier copper foil with a release layer; perform a water washing treatment on the carrier copper foil with the release layer;

[0013] S3, Preparation of the ultra-thin copper foil

[0014] After performing a water washing treatment on the carrier copper foil with the release layer obtained in step S2 as the cathode, immerse it in another electroplating copper solution at 30 - 70°C, with an iridium-coated titanium plate as the anode, and after electro-deposition, obtain the ultra-thin copper foil, and perform a water washing treatment on the ultra-thin copper foil.

[0015] Further, in step S1, the copper concentration in the electroplating copper solution is 40 - 100 g / L, the sulfuric acid concentration is 100 - 120 g / L, the polyethylene glycol concentration is 2 - 50 mg / L, and the sodium polydithiopropane sulfonate concentration is 1 - 10 mg / L; the current density during the electro-deposition process is 3.5 - 10 A / dm 2 , and the electrolysis time is 15 - 40 min.

[0016] Further, the ionic liquid in step S2 is a thiol-functionalized ionic liquid.

[0017] Further, the ionic liquids in step S2 are 1-(2-mercaptoethyl)-3-methylimidazolium bromide and 1-(4-mercaptobutyl)-3-methylimidazolium bromide.

[0018] Further, the concentration of 1-(2-mercaptoethyl)-3-methylimidazolium bromide and 1-(4-mercaptobutyl)-3-methylimidazolium bromide is 1 g / L - 5 g / L.

[0019] Further, the adsorption temperature in step S2 is 20 - 30°C, and the adsorption time ≥ 4 h.

[0020] Further, the electroplating copper solution in step S1 is the same as the electroplating copper solution in step S3.

[0021] Further, the current density during the electro-deposition process in step S3 is 3.5 - 10 A / dm 2 , and the electrolysis time is 2 - 6 min.

[0022] The present invention has the following beneficial effects:

[0023] 1. The present invention prepares an extremely thin and uniform single organic release layer through organic adsorption. The preparation process of this method is simple, and by regulating the bonding force between the carrier copper foil and the extremely thin copper foil, the extremely thin copper foil can be stably and completely peeled off from the carrier copper foil.

[0024] 2. In the present invention, the release layer is composed of ionic liquid. Due to the stability of the ionic liquid, the extremely thin copper foil can still be stably peeled off from the carrier copper foil after hot pressing. Moreover, the release layer is bonded to the extremely thin copper foil and the carrier copper foil through atomic bonding. By controlling the adsorption time of the release layer, the controllable adjustment of the peeling strength from high to low can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is the structural formula of 1-(2-mercaptoethyl)-3-methylimidazolium bromide in the embodiment of the present application;

[0026] Figure 2 is the structural formula of 1-(4-mercaptobutyl)-3-methylimidazolium bromide in the embodiment of the present application;

[0027] Figure 3 is the cross-sectional view of the carrier-attached extremely thin copper foil prepared in Example 3 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] In order to better understand the content of the present invention, the following specific embodiments will be used to further elaborate the present invention. The following embodiments are based on the technology of the present invention and give detailed implementation methods and operation steps, but the protection scope of the present invention is not limited to the following embodiments.

[0029] Referring to Figures 1 - 3 , the embodiment of the present application provides a method for preparing a carrier-attached extremely thin copper foil. Among them, the carrier-attached extremely thin copper foil includes a carrier copper foil layer, a release layer, and an extremely thin copper foil layer. The release layer is a new type of release layer - an ionic liquid release layer. The ionic liquid is a thiol-functionalized ionic liquid including 1-(2-mercaptoethyl)-3-methylimidazolium bromide and 1-(4-mercaptobutyl)-3-methylimidazolium bromide. The surface of the ionic liquid release layer is uniform and its performance is stable. Under its action, the extremely thin copper foil can be peeled off from the carrier copper foil with a stable and small force before and after hot pressing, and the specific strength can be controlled within 0.01 - 0.05 N / mm. It solves the problem that it is difficult to regulate the peeling strength between the release layer on the carrier copper foil and the interface of the extremely thin copper foil, and at the same time simplifies the process flow. Among them, the ionic liquid release layer exists on the carrier copper foil through simple adsorption and forms van der Waals force with the carrier copper foil.

[0030] It includes the following steps:

[0031] S1, Preparation of the carrier copper foil

[0032] Using a titanium plate as the cathode and an iridium-plated titanium plate as the anode, immerse the washed titanium plate in an electroplating copper solution at 30 - 70°C, and after electro-deposition, obtain the carrier copper foil. Specifically, in the electroplating copper solution, the copper concentration is 40 - 100 g / L, the sulfuric acid concentration is 100 - 120 g / L, the polyethylene glycol concentration is 2 - 50 mg / L, and the sodium polydithiopropane sulfonate concentration is 1 - 10 mg / L; the current density during electro-deposition is 3.5 - 10 A / dm 2 , and the electrolysis time is 15 - 40 min.

[0033] S2, Preparation of the release layer

[0034] After washing the carrier copper foil obtained in step S1, immerse it in an organic solution containing an ionic liquid for adsorption to obtain a carrier copper foil with a release layer. Specifically, the ionic liquid is a functionalized ionic liquid, preferably 1-(2-mercaptoethyl)-3-methylimidazolium bromide and 1-(4-mercaptobutyl)-3-methylimidazolium bromide, and the concentration of 1-(2-mercaptoethyl)-3-methylimidazolium bromide and 1-(4-mercaptobutyl)-3-methylimidazolium bromide is 1 g / L - 5 g / L. The adsorption temperature is 20 - 30°C, and the adsorption time is ≥4 h.

[0035] This embodiment is based on the advantages of ionic liquids being odorless, non-flammable, having a low vapor pressure, being usable in a high-vacuum system, reducing environmental pollution problems caused by volatilization, having a wide operable temperature range (-40 - 300°C), having good thermal stability and chemical stability, being designable and synthesizable according to the required functional groups, and having strong conductivity. The present invention synthesizes a thiol-functionalized ionic liquid. When using this ionic liquid as the release layer, after the extremely thin copper foil attached to the carrier is hot-pressed into a copper-clad laminate at high temperature, the purpose of easy peeling between the extremely thin copper foil and the carrier copper foil can be achieved.

[0036] S3, Preparation of the extremely thin copper foil

[0037] After washing the carrier copper foil with a release layer obtained in step S2 as the cathode, immerse it in another electroplating copper solution at 30 - 70°C, with an iridium-plated titanium plate as the anode, and after electro-deposition, obtain the extremely thin copper foil. Specifically, the current density during electro-deposition is 3.5 - 10 A / dm 2 , and the electrolysis time is 2 - 6 min.

[0038] Among them, polyethylene glycol and sodium bis(3-sulfopropyl) disulfide are additives in the process of depositing carrier copper foil. Polyethylene glycol is usually used as an inhibitor, which adsorbs on the surface of copper foil to slow down the deposition efficiency and improve the uniformity and dendritic structure of the coating. Sodium bis(3-sulfopropyl) disulfide acts as an accelerator to promote the reduction of copper ions, and cooperates with polyethylene glycol to balance the deposition kinetics and prevent dendritic growth.

[0039] Specifically, the components and the concentrations of each component of the electroplated copper solution in step S1 are the same as those of the electroplated copper solution in step S3.

[0040] In the present invention, an extremely thin and uniform single organic release layer is prepared by an organic adsorption method. The preparation process of this method is simple, and the release layer enables the extremely thin copper foil to be stably and completely peeled off from the carrier copper foil by regulating the bonding force between the carrier copper foil and the extremely thin copper foil.

[0041] In the present invention, the release layer is composed of ionic liquid. Due to the stability of the ionic liquid, the extremely thin copper foil can also be stably peeled off from the carrier copper foil after hot pressing. The release layer is bonded to the extremely thin copper foil and the carrier copper foil through atomic bonding. By controlling the adsorption time of the release layer, the controllable adjustment of the peeling strength from high to low can be achieved.

[0042] Example 1

[0043] This example provides a method for preparing a carrier-attached extremely thin copper foil, which includes the following steps:

[0044] S1, Preparation of carrier copper foil

[0045] Using an iridium-plated titanium plate as the anode, a titanium sheet as the cathode, and an acidic copper sulfate system as the electrolyte, where the concentration of copper sulfate is 110 g / L, the concentration of sulfuric acid is 100 g / L, the concentration of polyethylene glycol is 20 mg / L, the concentration of sodium bis(3-sulfopropyl) disulfide is 2 mg / L, the solution temperature is 35 °C, the current density is 4.5 A / dm 2 and the electrolysis time is 35 min. The obtained carrier copper foil is washed 3 times with deionized water. After the washing is completed, it is dried with cold air.

[0046] S2, Preparation of release layer

[0047] The electroplated carrier copper foil is immersed in a 1 g / L solution of 1-(2-mercaptoethyl)-3-methylimidazolium bromide, and after adsorbing for 5 h at 25 °C, an organic release layer is formed. Then, a water washing treatment is carried out.

[0048] S3, Preparation of extremely thin copper foil

[0049] The carrier copper foil after adsorption treatment is immersed as the cathode in the same solution as the electroplated copper solution in step S1 for electrodeposition to prepare an ultra-thin copper foil, with a current density of 4.5 A / dm 2 , and after electrolysis for 5 minutes, an ultra-thin copper foil is obtained, and the finally obtained ultra-thin copper foil is subjected to a water washing treatment.

[0050] Example 2

[0051] This example provides a method for preparing a carrier-attached ultra-thin copper foil, including the following steps:

[0052] S1, Preparation of the carrier copper foil

[0053] Using an iridium-plated titanium plate as the anode, a titanium sheet as the cathode, and an acidic copper sulfate system as the electrolyte, where the copper sulfate concentration is 110 g / L, the sulfuric acid concentration is 100 g / L, the polyethylene glycol concentration is 20 mg / L, the sodium poly(dithiopropane sulfonate) concentration is 2 mg / L, the solution temperature is 35 °C, and the current density is 4.5 A / dm 2 and the electrolysis time is 35 minutes. The obtained carrier copper foil is washed 3 times with deionized water, and after the washing is completed, it is dried with cold air.

[0054] S2, Preparation of the stripping layer

[0055] The carrier copper foil after electroplating treatment is immersed in a 1 g / L solution of 1-(2-mercaptoethyl)-3-methylimidazole bromide, and after adsorption at 25 °C for 10 h, an organic stripping layer is formed. Then, a water washing treatment is carried out.

[0056] S3, Preparation of the ultra-thin copper foil

[0057] The carrier copper foil after adsorption treatment is immersed as the cathode in the same solution as the electroplated copper solution in step S1 for electrodeposition to prepare an ultra-thin copper foil, with a current density of 4.5 A / dm 2 , and after electrolysis for 5 minutes, an ultra-thin copper foil is obtained, and the finally obtained ultra-thin copper foil is subjected to a water washing treatment.

[0058] Example 3

[0059] This example provides a method for preparing a carrier-attached ultra-thin copper foil, including the following steps:

[0060] S1, Preparation of the carrier copper foil

[0061] Using an iridium-plated titanium plate as the anode, a titanium sheet as the cathode, and an acidic copper sulfate system as the electrolyte, where the copper sulfate concentration is 110 g / L, the sulfuric acid concentration is 100 g / L, the polyethylene glycol concentration is 20 mg / L, the sodium poly(dithiopropane sulfonate) concentration is 2 mg / L, the solution temperature is 35 °C, and the current density is 4.5 A / dm 2And the electrolysis time is 35 min. The obtained carrier copper foil is washed 3 times with deionized water. After washing, it is dried with cold air.

[0062] S2, Preparation of the stripping layer

[0063] The electroplated carrier copper foil is immersed in a 1 g / L solution of 1-(2-mercaptoethyl)-3-methylimidazole bromide. After adsorbing for 15 h at 25 °C, an organic stripping layer is formed. Then, a water washing treatment is carried out.

[0064] S3, Preparation of the ultra-thin copper foil

[0065] The carrier copper foil after the adsorption treatment is used as the cathode and immersed in the same solution as the electroplating copper solution in step S1 for electrodeposition to prepare the ultra-thin copper foil. The current density is 4.5 A / dm 2 , and the ultra-thin copper foil is obtained after electrolysis for 5 min. Finally, the obtained ultra-thin copper foil is subjected to a water washing treatment.

[0066] Example 4

[0067] This example provides a method for preparing a carrier-attached ultra-thin copper foil, which includes the following steps:

[0068] S1, Preparation of the carrier copper foil

[0069] Using an iridium-plated titanium plate as the anode, a titanium sheet as the cathode, and an acidic copper sulfate system as the electrolyte, where the copper sulfate concentration is 110 g / L, the sulfuric acid concentration is 100 g / L, the polyethylene glycol concentration is 20 mg / L, the sodium polydithiopropanesulfonate concentration is 2 mg / L, the solution temperature is 35 °C, and the current density is 4.5 A / dm 2 And the electrolysis time is 35 min. The obtained carrier copper foil is washed 3 times with deionized water. After washing, it is dried with cold air.

[0070] S2, Preparation of the stripping layer

[0071] The electroplated carrier copper foil is immersed in a 1 g / L solution of 1-(2-mercaptoethyl)-3-methylimidazole bromide. After adsorbing for 20 h at 25 °C, an organic stripping layer is formed. Then, a water washing treatment is carried out.

[0072] S3, Preparation of the ultra-thin copper foil

[0073] The carrier copper foil after the adsorption treatment is used as the cathode and immersed in the same solution as the electroplating copper solution in step S1 for electrodeposition to prepare the ultra-thin copper foil. The current density is 4.5 A / dm 2 , and the ultra-thin copper foil is obtained after electrolysis for 5 min. Finally, the obtained ultra-thin copper foil is subjected to a water washing treatment.

[0074] Example 5

[0075] This embodiment provides a method for preparing a carrier ultra-thin copper foil, which includes the following steps:

[0076] S1. Preparation of the carrier copper foil

[0077] Using an iridium-plated titanium plate as the anode, a titanium sheet as the cathode, and an acidic copper sulfate system as the electrolyte, where the concentration of copper sulfate is 110 g / L, the concentration of sulfuric acid is 100 g / L, the concentration of polyethylene glycol is 20 mg / L, the concentration of sodium 3,3'-dithiodipropanesulfonate is 2 mg / L, the solution temperature is 35 °C, the current density is 4.5 A / dm 2 and the electrolysis time is 35 min. The obtained carrier copper foil is washed 3 times with deionized water. After washing, it is dried with cold air.

[0078] S2. Preparation of the stripping layer

[0079] The carrier copper foil after electroplating treatment is immersed in 1-(4-mercaptobutyl)-3-methylimidazolium bromide with a concentration of 1 g / L. After adsorbing for 20 h at 25 °C, an organic stripping layer is formed. Then, a water washing treatment is carried out.

[0080] S3. Preparation of the ultra-thin copper foil

[0081] The carrier copper foil after adsorption treatment is used as the cathode and immersed in the same solution as the electroplating copper solution in step S1 for electrodeposition to prepare the ultra-thin copper foil. The current density is 4.5 A / dm 2 , and the ultra-thin copper foil is obtained after electrolysis for 5 min. Finally, the obtained ultra-thin copper foil is subjected to a water washing treatment.

[0082] Comparative Example 1 (the stripping layer between the carrier copper foil and the ultra-thin copper foil is a single organic stripping layer)

[0083] S1. Preparation of the carrier copper foil

[0084] Using an iridium-plated titanium plate as the anode, a titanium sheet as the cathode, and an acidic copper sulfate system as the electrolyte, where the concentration of copper sulfate is 110 g / L, the concentration of sulfuric acid is 100 g / L, the additive is polyethylene glycol with a concentration of 20 mg / L, the concentration of sodium 3,3'-dithiodipropanesulfonate is 2 mg / L, the solution temperature is 35 °C, the current density is 4.5 A / dm 2 and the electrolysis time is 35 min. The obtained carrier copper foil is washed 3 times with deionized water. After washing, it is dried with cold air.

[0085] S2. Preparation of the organic stripping layer

[0086] The carrier copper foil after electro-deposition treatment is immersed in an organic solution with a concentration of 1 g / L for adsorption to form an organic layer, and finally the obtained organic stripping layer is subjected to the water washing treatment in step S1. The organic solution is preferably 2-mercaptobenzimidazole; the adsorption temperature is 30 °C and the adsorption time is 60 s.

[0087] S3, Preparation of ultra-thin copper foil

[0088] The carrier copper foil after adsorption treatment is used as the cathode and immersed in the same solution as the electroplating copper solution in step S1 for the electro-deposition preparation of ultra-thin copper foil, with a current density of 4.5 A / dm 2 , the electrolysis time is 5 min, and finally the obtained ultra-thin copper foil is subjected to water washing treatment.

[0089] The stripping layer of the carrier-attached ultra-thin copper foil prepared in Comparative Example 1 is composed of only a single organic layer. Compared with the stripping layer prepared in any embodiment of the present invention, the stripping strength of the carrier-attached ultra-thin copper foil before hot pressing in Comparative Example 1 is smaller, the ultra-thin copper foil is prone to fall off from the carrier copper foil, and the high-temperature and heat resistance is poor. After hot pressing, the ultra-thin copper foil cannot be peeled off from the carrier copper foil.

[0090] Comparative Example 2 (the stripping layer between the carrier copper foil and the ultra-thin copper foil is a single metal stripping layer)

[0091] S1, Preparation of carrier copper foil

[0092] Using an iridium-plated titanium plate as the anode, a titanium plate as the cathode, and an acidic copper sulfate system as the electrolyte, where the copper sulfate concentration is 110 g / L, the sulfuric acid concentration is 100 g / L, the additive is polyethylene glycol with a concentration of 20 mg / L, the sodium poly(dithiopropanesulfonate) concentration is 2 mg / L, the solution temperature is 35 °C, the current density is 4.5 A / dm 2 and the electrolysis time is 35 min. The obtained carrier copper foil is washed 3 times with deionized water. After the washing is completed, it is dried with cold air.

[0093] S2, Preparation of metal stripping layer

[0094] The carrier copper foil after electro-deposition treatment is used as the cathode and placed in an electroplating bath with an electroplating solution temperature of 30 °C for electroplating to obtain a metal stripping layer, and the obtained metal stripping layer is subjected to water washing treatment. The components of the electroplating solution are 4 g / L of zinc sulfate, 4 g / L of nickel sulfate, 0.02 g / L of sodium dodecyl sulfate, and the current density is 1.7 A / dm 2 , and the electroplating time is 10 s.

[0095] S3, Preparation of ultra-thin copper foil

[0096] The electroplated carrier copper foil is used as the cathode and immersed in the same solution as the electroplating copper solution in step S1 to prepare an extremely thin copper foil by electrodeposition. The current density is 4.5 A / dm 2 , the electrolysis time is 5 min, and finally the obtained extremely thin copper foil is washed with water.

[0097] The release layer of the carrier-attached extremely thin copper foil prepared in Comparative Example 2 is composed of only a single zinc-nickel alloy metal layer. Compared with the composite release layer prepared in any embodiment of the present invention, the release strength of the carrier-attached extremely thin copper foil in Comparative Example 2 is too high, and the complete separation of the extremely thin copper foil from the carrier copper foil cannot be achieved.

[0098] The specific release strength data of Examples 1-4 are as follows in the table:

[0099]

[0100]

[0101] Figure 3 FIG. is a cross-sectional view of the carrier-attached extremely thin copper foil prepared in Example 3 of the present invention. It can be seen from the figure that the extremely thin copper foil is on the upper side of the carrier copper foil, and the boundary between the two is clear and easy to separate, that is, the ionic liquid release layer can effectively separate the carrier copper foil from the extremely thin copper foil.

[0102] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A preparation method of a carrier-attached extremely thin copper foil, characterized in that, It includes the following steps: S1. Preparation of carrier copper foil Using a titanium plate as the cathode and an iridium-plated titanium plate as the anode, immersing the washed titanium plate in an electroplating copper solution at 30 - 70 °C, and after electro-deposition, obtaining the carrier copper foil; performing a water washing treatment on the carrier copper foil; S2. Preparation of the release layer Immersing the carrier copper foil obtained in step S1 in an organic solution containing an ionic liquid for adsorption to obtain a carrier copper foil with a release layer; performing a water washing treatment on the carrier copper foil with the release layer; S3. Preparation of ultra-thin copper foil Taking the carrier copper foil with a release layer obtained in step S2 as the cathode, performing a water washing treatment and then immersing it in another electroplating copper solution at 30 - 70 °C, using an iridium-plated titanium plate as the anode, and after electro-deposition, obtaining the ultra-thin copper foil, and performing a water washing treatment on the ultra-thin copper foil.

2. The preparation method of the carrier extremely thin copper foil according to claim 1, characterized in that In step S1, the copper concentration in the copper electroplating solution is 40 - 100 g / L, the sulfuric acid concentration is 100 - 120 g / L, the polyethylene glycol concentration is 2 - 50 mg / L, and the sodium polydithiopropane sulfonate concentration is 1 - 10 mg / L; the current density during the electrodeposition process is 3.5 - 10 A / dm 2 , and the electrolysis time is 15 - 40 min.

3. The preparation method of the carrier extremely thin copper foil according to claim 1, characterized in that, The ionic liquid in step S2 is a thiol-functionalized ionic liquid.

4. The preparation method of the carrier extremely thin copper foil according to claim 1, characterized in that The ionic liquids in step S2 are 1-(2-mercaptoethyl)-3-methylimidazolium bromide and 1-(4-mercaptobutyl)-3-methylimidazolium bromide.

5. The preparation method of the carrier extremely thin copper foil according to claim 4, characterized in that, The concentration of 1-(2-mercaptoethyl)-3-methylimidazolium bromide and 1-(4-mercaptobutyl)-3-methylimidazolium bromide is 1 g / L - 5 g / L.

6. The preparation method of the carrier ultra-thin copper foil according to claim 1, wherein, The adsorption temperature in step S2 is 20 - 30 °C, and the adsorption time is ≥ 4 h.

7. The manufacturing method of the carrier extremely thin copper foil according to claim 1, characterized in that The electroplating copper solution in step S1 is the same as the electroplating copper solution in step S3.

8. The method for preparing a carrier extremely thin copper foil according to claim 1, characterized in that, In step S3, the current density during the electroplating process is 3.5 - 10 A / dm 2 , and the electrolysis time is 2 - 6 minutes.

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