A method and system for double-sided electroplating of flexible substrate

Abstract

The embodiments of the present application relate to the field of electroplating, and in particular, to a method and system for double-sided electroplating of a flexible substrate. The method and system execution steps include: setting a reservoir, injecting a mixed electrolyte into the reservoir, the mixed electrolyte including an electrolyte and an additive; connecting the reservoir and the electroplating tank through a circulation pipeline; circulating the electrolyte in the reservoir and the electroplating tank; driving the flexible substrate to continuously pass through the electroplating tank for electroplating; and replenishing the electrolyte and additives into the reservoir. The present invention ensures the uniformity and consistency of the coating thickness during continuous electroplating of the flexible substrate, and can effectively reduce the maximum thickness of the coating. At the same time, by replenishing the electrolyte and additives into the reservoir, the electrolyte and additives can be fully premixed in the reservoir with the help of the circulating water flow, so that the concentrations of various effective components in the mixed electrolyte are uniform.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of electroplating, and in particular to a method and system for double-sided electroplating of a flexible substrate. Background Art

[0002] With the development of various electronic products and battery technologies, composite copper foil products formed by copper coating on flexible substrates such as polymer films have been widely used in the industry as electronic devices. For example, they can be used as the negative electrode of the battery, wiring, and other usage scenarios that require conductivity and small thickness. Such composite copper foils are generally electroplated with bright copper layers on both sides of the polymer film. When processing such copper foil products, the existing composite copper foils first need to be coated with a metal film layer on the surface of the flexible substrate by deposition methods such as multi-arc ion plating, and then the flexible substrate with the metal film layer is electroplated by electroplating to adjust the thickness or metal material of the surface metal film layer.

[0003] Patent No. 2010105103576, entitled "Continuous electroplating device for thin film and method for continuous electroplating of thin film", discloses a device and method for continuous electroplating of thin film, which is used to solve the problem of rewinding a film roll after continuously unwinding it through the electroplating tank. The disadvantage of this method is that the effective components of the electrolyte and additives in the electroplating tank are continuously reduced as the continuous electroplating proceeds, and the concentration of the effective components needs to be continuously detected and added in time. From the beginning of electroplating to the next addition, the saturation of the electrolyte shows a dynamic downward trend. The potential returns to high saturation after addition, which is reflected in the coating thickness showing a staged change and uneven coating thickness. Therefore, in order to ensure that the thinnest part of the coating has an effective thickness, its general thickness requirement is relatively large, at least 6-7μm or more. Combined with the thickness of the substrate, the thickness of the overall copper foil product is even greater, which does not meet the existing battery miniaturization and special-shaped use needs. Moreover, directly adding electrolyte and additives to the plating tank cannot ensure that the newly added electrolyte and additives are diffused in a timely and uniform manner, resulting in uneven concentration of effective components in the electrolyte in the plating tank, which also affects the electroplating effect. Summary of the invention

[0004] In a first aspect, the embodiments of the present application provide a method for double-sided electroplating of a flexible substrate that effectively avoids periodic changes in the concentration of electroplating materials and reduces the thickness and uniformity of the coating.

[0005] The method comprises the following steps: The steps include: An electroplating tank and a liquid storage tank are provided, a mixed electrolyte is injected into the electroplating tank and the liquid storage tank, two layers of anode plates are provided in the electroplating tank, and the mixed electrolyte includes an electrolyte and an additive; Connect the liquid storage tank and the electroplating tank via a circulation pipeline; The mixed electrolyte is circulated in the storage tank and the electroplating tank at a set flow rate; The flexible substrate with negative charge on the surface is driven to pass continuously between two anode plates of the electroplating tank for electroplating; Continuously replenishing the electrolyte and the additive into the liquid storage tank according to the consumption of the electrolyte and the additive in the electroplating tank; A double-sided bright coating with a thickness of 1-2 μm, a roughness of 0.1-0.2 μm and a glossiness of 250-500 is electroplated on both sides of the flexible substrate.

[0006] Due to the adoption of the above-mentioned scheme, the double-sided electroplating method for a flexible substrate in an embodiment of the present application allows the electrolyte to circulate between the liquid reservoir and the electroplating tank during the electroplating process through the liquid reservoir, the circulation pipeline and the electroplating tank, and the effective components of the electrolyte in the electrolytic tank are maintained in a constant range by adding electrolyte and additives to the liquid reservoir, thereby ensuring the uniformity and consistency of the coating thickness during continuous electroplating of the flexible substrate, and can effectively reduce the maximum thickness of the coating. At the same time, by adding electrolyte and additives to the liquid reservoir, the electrolyte and additives can be fully premixed in the liquid reservoir with the help of circulating water flow, so that the concentrations of various effective components in the mixed electrolyte are uniform.

[0007] In a possible implementation, the copper ion concentration in the mixed electrolyte in the electroplating tank and the liquid storage tank is 30-70 g / L; the sulfuric acid concentration is 80-150 g / L.

[0008] In a possible implementation, the additives include a first additive, a second additive, a third additive and a fourth additive, the first additive is a polyether compound containing a -(CH2OCH2)n- structure in its molecular structure, the second additive is an organic sulfide, the third additive is a heterocyclic sulfide, and the fourth additive is a phenazine organic dye, and the concentration of the first additive in the mixed electrolyte is 20-150 mg / L; the concentration of the second additive in the mixed electrolyte is 0.5-10 mg / L; the concentration of the third additive in the mixed electrolyte is 0.5-10 mg / L; the concentration of the fourth additive in the mixed electrolyte is 2-20 mg / L.

[0009] In a possible implementation, the circulation pipeline includes an inlet pump for conveying the mixed electrolyte from the liquid storage tank to the electroplating tank, an inlet pipe connected to the inlet pump, and a reflux pipe for returning the electrolyte from the electroplating tank to the liquid storage tank.

[0010] In a possible implementation, the step of driving the flexible substrate to continuously pass through the electroplating tank for electroplating further comprises: The conductive roller makes the surfaces of both sides of the flexible substrate passing through the mixed electrolyte in the electroplating tank be negatively charged.

[0011] In a possible implementation, the step of driving the flexible substrate to continuously pass through the electroplating tank for electroplating further comprises: The flexible substrate is driven by a conductive roller to pass through the electroplating tank at a line speed of 2-10m / min to mix the electrolyte.

[0012] In a possible implementation, replenishing the electrolyte and additives into the liquid storage tank includes: An electrolyte replenishing tank for storing copper sulfate solution is provided, and the electrolyte replenishing tank enters the liquid storage tank to replenish the Cu ions consumed by electrolysis according to the copper ion consumption in the electroplating process, and the electrolyte is replenished into the liquid storage tank according to the copper ion concentration and replenishment speed in the electrolyte replenishing tank; An additive storage tank is provided for storing additives, and the additive storage tank enters the liquid storage tank at a flow rate of 2-10 ml / min to replenish the additive consumed by electrolysis. The first additive, the second additive, the third additive and the fourth additive in the additive storage tank are mixed in a ratio of 90:4:1:6.

[0013] In a possible implementation, the electrolyte replenishing tank and the additive storage tank replenish the electrolyte or the additive into the storage tank respectively through a peristaltic pump.

[0014] In a second aspect, an embodiment of the present application further provides a flexible substrate double-sided electroplating system, characterized in that the system comprises: The substrate conveying mechanism comprises a feed conductive roller and a discharge conductive roller, wherein the feed conductive roller and the discharge conductive roller work synchronously to convey and make the A side and the B side of the flexible substrate negatively charged; The electroplating tank is used to store the mixed electrolyte for electroplating, and is arranged between the feeding conductive roller and the discharging conductive roller, and comprises a first tank body for storing the mixed electrolyte and a first anode plate and a second anode plate arranged in the first tank body, wherein the first anode plate and the second anode plate are arranged in parallel and a gap is arranged between them for the flexible substrate to pass through; A liquid storage tank, used for storing a mixed electrolyte for circulation, comprising a second tank body; The circulation pipeline includes a liquid inlet pipeline and a reflux pipeline connected with the electroplating tank and the liquid storage tank. The liquid inlet pipeline includes a liquid inlet pump arranged in the liquid storage tank.

[0015] A supplement component, comprising an electrolyte supplement component and an additive supplement component, wherein: The electrolyte replenishing assembly comprises an electrolyte replenishing tank and an electrolyte replenishing pipeline connecting the electrolyte replenishing tank and the liquid storage tank, and a first peristaltic pump is provided on the electrolyte replenishing pipeline; The additive supplement component comprises an additive storage tank and an additive supplement pipeline connecting the additive storage tank and the liquid storage tank, and a second peristaltic pump is arranged on the additive pipeline.

[0016] In a possible implementation, the length of the anode plate is 0.5 m-10 m. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A system structure diagram of an embodiment of the present invention; Figure 2 This is a surface appearance diagram of a thin film surface electroplated copper product according to an embodiment of the present invention; Figure 3 This is the scanning electron microscope surface morphology of the thin film surface electroplated copper product according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail by way of implementation methods with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, but not all of the embodiments. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0020] It should be noted that: in the accompanying drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions; in the description of the present application, the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; in the description of the present application, "first", "second", etc. are only used to distinguish elements of the same type from each other, rather than to indicate their importance and order, etc.

[0021] The purpose of the embodiment of the present application is to produce a composite copper foil product for battery negative electrode, electroplating a 1-2μm bright copper layer on both sides of a 4-6μm polymer film, requiring the electroplated copper layer to have a uniform thickness of ±0.1μm, a surface roughness of Ra0.1-1.3μm, and a glossiness of 250-500.

[0022] The first embodiment of the present application provides a method for double-sided electroplating of a flexible substrate, which effectively avoids periodic changes in the concentration of electroplating materials and reduces the thickness and uniformity of the plating layer.

[0023] The method comprises the following steps: An electroplating tank and a liquid storage tank are provided, a mixed electrolyte is injected into the electroplating tank and the liquid storage tank, two layers of anode plates are provided in the electroplating tank, and the mixed electrolyte includes an electrolyte and an additive; Connect the liquid storage tank and the electroplating tank via a circulation pipeline; The electrolyte is made to circulate in the storage tank and the electroplating tank at a set flow rate; The flexible substrate with negative charge on the surface is driven to pass continuously between two anode plates of the electroplating tank for electroplating; Continuously replenishing the electrolyte and the additive into the liquid storage tank according to the consumption of the electrolyte and the additive in the electroplating tank; A double-sided bright coating with a thickness of 1-2 μm, a roughness of 0.1-0.2 μm and a glossiness of 250-500 is electroplated on both sides of the flexible substrate.

[0024] Among them, in the initial state of this embodiment, the length of the anode plate in the electroplating tank is 3m and the width is 0.3m. A mixed solution of copper sulfate solution and sulfuric acid is injected into the electroplating tank and the liquid storage tank as an electrolyte, and the copper ion concentration in the mixed electrolyte is 70g / L; the sulfuric acid concentration is 150g / L. Under the electroplating layer specifications required by this embodiment, if the copper ion concentration is too high, copper sulfate crystals will be formed at room temperature, and if the copper ion concentration is too low, the number of copper crystal particles will be small, and the copper film will be incomplete; sulfuric acid is used to adjust the crystallization speed of electroplated copper, and if the sulfuric acid concentration is low, the copper crystallization speed will be low and the surface will be uneven, and if the sulfuric acid concentration is too high, hydrogen precipitation will cause bubbles to form in the copper film.

[0025] In this embodiment, the additives include a first additive, a second additive, a third additive and a fourth additive, the first additive is a polyether compound containing a -(CH2OCH2)n- structure in its molecular structure, the second additive is an organic sulfide, the third additive is a heterocyclic sulfide, and the fourth additive is a phenazine organic dye. The concentration of the first additive in the mixed electrolyte in the plating tank and the liquid storage tank is 20 mg / L, the concentration of the second additive is 0.5 mg / L, the concentration of the third additive is 0.5 mg / L, and the concentration of the fourth additive is 2 mg / L.

[0026] In this embodiment, the first additive includes at least one of polyethylene glycol, aliphatic polyethylene glycol ether, and aromatic polyethylene ether, the second additive includes at least one of sodium polydisulfide propane sulfonate, sodium polydisulfide propane sulfonate, and sodium phenyl polydisulfide propane sulfonate, the third additive includes at least one of 2-mercaptothiazole, 2-tetrahydroimidazolethione, 2-mercaptobenzimidazole, and 2-mercaptopyridine, and the fourth additive includes at least one of Janus Green and Janus Black.

[0027] In this embodiment, the first additive improves cathode polarization during electroplating, reduces pinholes and gauze, and plays a leveling role; the second additive plays a grain refinement role and improves the tensile strength of the copper layer; the third additive improves the surface gloss of the copper film; and the fourth additive is used to improve the brightness and leveling of the low current density area.

[0028] In this embodiment, when the flexible substrate is driven to continuously pass through the electroplating tank for electroplating, the surface of the flexible substrate passing through the mixed electrolyte in the electroplating tank is negatively charged by the conductive roller, and the current density is maintained at 5A / dm 2 The flexible substrate is driven by a conductive roller to pass through the electroplating tank at a line speed of 2m / min to mix the electrolyte.

[0029] In order to automatically replenish the electrolyte and additives into the liquid storage tank, an electrolyte replenishing tank and an additive storage tank are provided in this embodiment.

[0030] Due to the adoption of the above-mentioned scheme, the double-sided electroplating method for a flexible substrate of the first embodiment allows the electrolyte to circulate between the liquid reservoir and the electroplating tank during the electroplating process through the liquid reservoir, the circulation pipeline and the electroplating tank. The effective components of the electrolyte in the electrolytic tank are kept in a constant range by adding electrolyte and additives to the liquid reservoir, thereby ensuring the uniformity and consistency of the coating thickness during continuous electroplating of the flexible substrate, and can effectively reduce the maximum thickness of the coating. At the same time, by adding electrolyte and additives to the liquid reservoir, the electrolyte and additives can be fully premixed in the liquid reservoir with the help of circulating water flow, so that the concentrations of various effective components in the mixed electrolyte are uniform.

[0031] Based on the steps in the above first embodiment, a second embodiment is further proposed.

[0032] In the second embodiment, a mixture of copper sulfate solution and sulfuric acid is still used as the electrolyte. The anode plate in the electroplating tank is 10m long and 0.75m wide. The copper ion concentration in the mixed electrolyte is 30g / L; the sulfuric acid concentration is 80g / L.

[0033] The additives include a first additive, a second additive, a third additive and a fourth additive, wherein the first additive is a polyether compound containing a -(CH2OCH2)n- structure in its molecular structure, the second additive is an organic sulfide, the third additive is a heterocyclic sulfide, and the fourth additive is a phenazine organic dye. The concentration of the first additive in the mixed electrolyte in the electroplating tank and the liquid storage tank is 150 mg / L, the concentration of the second additive is 10 mg / L, the concentration of the third additive is 10 mg / L, and the concentration of the fourth additive is 20 mg / L.

[0034] Similar to the first embodiment, in the second embodiment, the first additive includes at least one of polyethylene glycol, aliphatic polyethylene glycol ether, and aromatic polyethylene ether, the second additive includes at least one of sodium polydisulfide propane sulfonate, sodium polydisulfide propane sulfonate, and sodium phenyl polydisulfide propane sulfonate, the third additive includes at least one of 2-mercaptothiazole, 2-tetrahydroimidazolethione, 2-mercaptobenzimidazole, and 2-mercaptopyridine, and the fourth additive includes at least one of Janus Green and Janus Black.

[0035] Similar to the first embodiment, in the second embodiment, the first additive improves cathode polarization during electroplating, reduces pinholes and gauze, and plays a leveling role; the second additive plays a grain refinement role and improves the tensile strength of the copper layer; the third additive improves the surface gloss of the copper film; and the fourth additive is used to improve the brightness and leveling of the low current density area.

[0036] In this embodiment, when the flexible substrate is driven to continuously pass through the electroplating tank for electroplating, the surface of the flexible substrate passing through the mixed electrolyte in the electroplating tank is negatively charged by the conductive roller, and the current density is maintained at 0.5A / dm 2 The flexible substrate is driven by a conductive roller to pass through the electroplating tank at a line speed of 2m / min to mix the electrolyte.

[0037] Furthermore, a third embodiment is proposed based on the process steps of the first embodiment.

[0038] In the third embodiment, a mixture of copper sulfate solution and sulfuric acid is still used as the electrolyte. The anode plate in the electroplating tank is 10 m long and 0.3 m wide. The copper ion concentration in the mixed electrolyte is 50 g / L; the sulfuric acid concentration is 100 g / L.

[0039] The additives include a first additive, a second additive, a third additive and a fourth additive, wherein the first additive is a polyether compound containing a -(CH2OCH2)n- structure in its molecular structure, the second additive is an organic sulfide, the third additive is a heterocyclic sulfide, and the fourth additive is a phenazine organic dye. The concentration of the first additive in the mixed electrolyte in the electroplating tank and the liquid storage tank is 90 mg / L, the concentration of the second additive is 1 mg / L, the concentration of the third additive is 1 mg / L, and the concentration of the fourth additive is 6 mg / L.

[0040] In this embodiment, the first additive is polyethylene glycol, the second additive includes sodium polydisulfide dipropane sulfonate, the third additive includes 2-mercaptobenzimidazole, and the fourth additive includes Janus Green.

[0041] In this embodiment, the first additive improves cathode polarization during electroplating, reduces pinholes and gauze, and plays a leveling role; the second additive plays a grain refinement role and improves the tensile strength of the copper layer; the third additive improves the surface gloss of the copper film; and the fourth additive is used to improve the brightness and leveling of the low current density area.

[0042] In this embodiment, when the flexible substrate is driven to continuously pass through the electroplating tank for electroplating, the surface of the flexible substrate passing through the mixed electrolyte in the electroplating tank is negatively charged by the conductive roller, and the current density is maintained at 3A / dm 2 The flexible substrate is driven by a conductive roller to pass through the electroplating tank at a line speed of 2m / min to mix the electrolyte.

[0043] Through the above process, copper is electroplated on the surface of the polymer film. Figure 2 and Figure 3 As shown, the copper film thickness on the surface of the polymer film is 1 μm, the surface roughness Ra is 0.16 μm, and the glossiness is 456.

[0044] The fourth embodiment of the present application provides an implementation scheme for automatically adding electrolyte and additives to the storage tank through the electrolyte replenishment tank and the additive storage tank in the above-mentioned first to third embodiments.

[0045] The electrolyte replenishing tank replenishes the electrolyte to the storage tank according to the concentration of copper ions consumed by electroplating. So, let the electroplating area be M (dm 2 ), current density is i(A / dm 2 ), the current required for electroplating is 2Mi (A). Under this current, the amount of copper metal deposited per hour is 1.186×2Mi (g / h). If the copper ion concentration in the electrolyte in the electrolyte replenishing tank is N (g / L), then the flow rate of replenishing the electrolyte from the electrolyte replenishing tank to the reservoir is 1.186×2Mi / N (L / h).

[0046] In view of the electroplating parameters in the first to second embodiments mentioned above, the copper ion concentration of the copper sulfate solution in the electrolyte replenishing tank in this embodiment is 90-180 g / L, and it is replenished at a flow rate of 2-10 L / h. The copper ion concentration of the copper sulfate solution in the electrolyte replenishing tank in the third embodiment is 120 g / L and the flow rate is 5 L / h.

[0047] Accordingly, the additives in the additive storage tank are mixed in a ratio of A:B:C:D=90:4:1:6, and a proper amount of water is added to dissolve them, and the mixture enters the liquid storage tank at a flow rate of 6 ml / min to replenish the additives consumed by electrolysis.

[0048] The fourth embodiment of the present application provides a flexible substrate double-sided electroplating system, such as Figure 1 As shown, the system includes: The substrate conveying mechanism 1 comprises a feed conductive roller 11 and a discharge conductive roller 12, wherein the feed conductive roller 11 and the discharge conductive roller 12 work synchronously to convey and make the A surface and the B surface of the flexible substrate negatively charged; The electroplating tank 2 is used to store the mixed electrolyte for electroplating, and is disposed between the feeding conductive roller and the discharging conductive roller, and includes a first tank body for storing the mixed electrolyte and a first anode plate 21 and a second anode plate 22 disposed in the first tank body. The first anode plate and the second anode plate are disposed in parallel and a gap is disposed between them for the flexible substrate to pass through. A liquid storage tank 3, used for storing a mixed electrolyte for circulation, comprising a second tank body; The circulation pipeline 4 includes a liquid inlet pipeline 41 and a reflux pipeline 42 connected to the electroplating tank and the liquid storage tank. The liquid inlet pipeline includes a liquid inlet pump 43 arranged in the liquid storage tank.

[0049] A supplement component, comprising an electrolyte supplement component and an additive supplement component, wherein: The electrolyte replenishing assembly comprises an electrolyte replenishing tank 5 and an electrolyte replenishing pipeline 51 connecting the electrolyte replenishing tank 5 and the liquid storage tank 3, and a first peristaltic pump 52 is provided on the electrolyte replenishing pipeline 51; The additive replenishing assembly includes an additive storage tank 6 and an additive replenishing pipeline 61 connecting the additive storage tank 6 and the liquid storage tank 3 . A second peristaltic pump 62 is disposed on the additive pipeline 61 .

[0050] The flexible substrate double-sided electroplating system in this embodiment performs the processing steps in the first to third embodiments described above.

[0051] A 70nm thick copper film is deposited on the surface of a 4-6μm polymer film by a substrate conveying mechanism 1. The polymer film is a coil with a diameter of 200mm, a length of about 5000m and a width of 350mm. The copper film is thickened from 70nm to 1μm.

[0052] The above description is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for double-sided electroplating of a flexible substrate, characterized in that: The steps include: An electroplating tank and a liquid storage tank are provided, a mixed electrolyte is injected into the electroplating tank and the liquid storage tank, two layers of anode plates are provided in the electroplating tank, and the mixed electrolyte includes an electrolyte and an additive; Connect the liquid storage tank and the electroplating tank via a circulation pipeline; The mixed electrolyte is circulated in the storage tank and the electroplating tank at a set flow rate; The flexible substrate with negative charge on the surface is driven to pass continuously between two anode plates of the electroplating tank for electroplating; Continuously replenishing the electrolyte and the additive into the liquid storage tank according to the consumption of the electrolyte and the additive in the electroplating tank; A double-sided bright coating with a thickness of 1-2 μm, a roughness of 0.1-0.2 μm and a glossiness of 250-500 is electroplated on both sides of the flexible substrate.

2. A method and system for double-sided electroplating of a flexible substrate as claimed in claim 1, characterized in that: The copper ion concentration in the mixed electrolyte in the electroplating tank and the liquid storage tank is 30-70 g / L; the sulfuric acid concentration is 80-150 g / L.

3. A method and system for double-sided electroplating of a flexible substrate as claimed in claim 1, characterized in that: The additives include a first additive, a second additive, a third additive and a fourth additive, wherein the first additive is a polyether compound containing a -(CH2OCH2)n- structure in its molecular structure, the second additive is an organic sulfide, the third additive is a heterocyclic sulfide, and the fourth additive is a phenazine organic dye; The concentration of the first additive in the mixed electrolyte is 20-150 mg / L, the concentration of the second additive in the mixed electrolyte is 0.5-10 mg / L, the concentration of the third additive in the mixed electrolyte is 0.5-10 mg / L, and the concentration of the fourth additive in the mixed electrolyte is 2-20 mg / L.

4. A method and system for double-sided electroplating of a flexible substrate as claimed in claim 1, characterized in that: The circulation pipeline includes a liquid inlet pump for conveying mixed electrolyte from the liquid storage tank to the electroplating tank, a liquid inlet pipe connected to the liquid inlet pump, and a reflux pipe for reflux from the electroplating tank to the liquid storage tank.

5. A method and system for double-sided electroplating of a flexible substrate as claimed in claim 1, characterized in that: The driving of the flexible substrate to continuously pass through the electroplating tank for electroplating further comprises: The flexible substrate is driven to run continuously by a conductive roller so that the surfaces of both sides of the flexible substrate passing through the mixed electrolyte in the electroplating tank are negatively charged.

6. A method and system for double-sided electroplating of a flexible substrate as claimed in claim 1, characterized in that: The driving of the flexible substrate to continuously pass through the electroplating tank for electroplating further comprises: The flexible substrate is driven by a conductive roller to pass through the electroplating tank at a line speed of 2-10m / min to mix the electrolyte.

7. A method and system for double-sided electroplating of a flexible substrate as claimed in claim 1, characterized in that: The replenishing of electrolyte and additives into the liquid storage tank comprises: An electrolyte replenishing tank for storing copper sulfate solution is provided, and the electrolyte replenishing tank enters the liquid storage tank to replenish the Cu ions consumed by electrolysis according to the copper ion consumption in the electroplating process, and the electrolyte is replenished into the liquid storage tank according to the copper ion concentration and replenishment speed in the electrolyte replenishing tank; An additive storage tank is provided for storing additives, and the additive storage tank enters the liquid storage tank at a flow rate of 2-10 ml / min to replenish the additive consumed by electrolysis. The first additive, the second additive, the third additive and the fourth additive in the additive storage tank are mixed in a ratio of 90:4:1:

6.

8. A method and system for double-sided electroplating of a flexible substrate as claimed in claim 7, characterized in that: The electrolyte replenishing tank and the additive storage tank replenish the electrolyte or the additive into the storage tank respectively through the peristaltic pump.

9. A flexible substrate double-sided electroplating system, characterized in that: The system includes: The substrate conveying mechanism comprises a feed conductive roller and a discharge conductive roller, wherein the feed conductive roller and the discharge conductive roller work synchronously to convey and make the A side and the B side of the flexible substrate negatively charged; The electroplating tank is used to store the mixed electrolyte for electroplating, and is arranged between the feeding conductive roller and the discharging conductive roller, and comprises a first tank body for storing the mixed electrolyte and a first anode plate and a second anode plate arranged in the first tank body, wherein the first anode plate and the second anode plate are arranged in parallel and a gap is arranged between them for the flexible substrate to pass through; A liquid storage tank, used for storing a mixed electrolyte for circulation, comprising a second tank body; A circulation pipeline, including a liquid inlet pipeline and a reflux pipeline connected to the electroplating tank and the liquid storage tank, wherein the liquid inlet pipeline includes a liquid inlet pump disposed in the liquid storage tank; A supplement component, comprising an electrolyte supplement component and an additive supplement component, wherein: The electrolyte replenishing assembly comprises an electrolyte replenishing tank and an electrolyte replenishing pipeline connecting the electrolyte replenishing tank and the liquid storage tank, and a first peristaltic pump is provided on the electrolyte replenishing pipeline; The additive supplement component comprises an additive storage tank and an additive supplement pipeline connecting the additive storage tank and the liquid storage tank, and a second peristaltic pump is arranged on the additive pipeline.

10. A flexible substrate double-sided electroplating system as claimed in claim 9, characterized in that: The length of the anode plate is 0.5m-10m.

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