An additive for electrolytic copper foil, an electrolyte and a method for preparing electrolytic copper foil
By adding polyvinylpyrrolidone as an additive to the electrolyte, combined with other components and optimized electrodeposition conditions, the problems of insufficient surface smoothness and corrosion resistance of electrolytic copper foil were solved, enabling the preparation of high-quality electrolytic copper foil, reducing costs and simplifying the process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIUJIANG TELFORD ELECTRONICS MATERIAL CO LTD
- Filing Date
- 2026-03-30
- Publication Date
- 2026-06-05
AI Technical Summary
Existing electrolytic copper foils lack surface smoothness and corrosion resistance, have high manufacturing costs, and involve complex manufacturing processes.
Polyvinylpyrrolidone was used as an additive in the electrolyte, and electrolytic copper foil was prepared by electrodeposition process using specific concentrations of sodium 3-mercaptopropanesulfonate, polyethylene glycol, copper sulfate, sulfuric acid and chloride ions. The current density and electrode spacing were controlled and the electrolyte composition was optimized to improve the quality of the copper foil.
It significantly reduces the rough grain size of electrolytic copper foil, improves surface smoothness and corrosion resistance, reduces manufacturing costs, and simplifies the manufacturing process.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrolytic copper foil technology, and particularly relates to an additive for electrolytic copper foil, an electrolyte, and a method for preparing electrolytic copper foil. Background Technology
[0002] Copper foil is widely used in electrical and electronic component industries such as semiconductors and printed circuit boards (PCBs), including electric vehicles, drones, and robotics. With the development of these industries, the demand for copper foil is rapidly increasing. As the neural network for signal and power transmission in electronic products, copper foil materials directly affect the quality and performance of semiconductors, printed circuit boards, and batteries.
[0003] Initially, rolled copper foil was the primary material used. However, due to its complex manufacturing process, high production cost, and inconsistent quality, electrolytic copper foil has recently become the main choice. Electrolytic copper foil offers advantages such as uniform quality, simple manufacturing process, and reduced manufacturing costs. The quality of electrolytic copper foil depends on process variables, including current density, electrolyte concentration, and the distance between the cathode and anode. In particular, the composition of the electrolyte has a significant impact. Summary of the Invention
[0004] In view of this, the purpose of the present invention is to provide an additive for electrolytic copper foil, an electrolyte, and a method for preparing electrolytic copper foil, wherein polyvinylpyrrolidone is used as one of the additives in the electrolyte, which can improve the surface smoothness and corrosion resistance of the electrolytic copper foil.
[0005] The present invention provides an additive for electrolytic copper foil, comprising polyvinylpyrrolidone.
[0006] Preferably, the molecular weight of polyvinylpyrrolidone is 38,000 to 42,000.
[0007] The present invention provides an electrolyte for electrolytic copper foil, comprising 9.5~10.5 ppm sodium 3-mercaptopropanesulfonate, 28~32 ppm polyethylene glycol, 88~92 g / L copper sulfate, 97~102 g / L sulfuric acid, 48~53 ppm chloride ions and 10~40 ppm polyvinylpyrrolidone.
[0008] Preferably, the composition includes 10 ppm sodium 3-mercaptopropanesulfonate, 30 ppm polyethylene glycol, 90 g / L copper sulfate, 100 g / L sulfuric acid, and 50 ppm chloride ions.
[0009] Preferably, the polyvinylpyrrolidone is 15-25 ppm.
[0010] Preferably, the polyvinylpyrrolidone is 20-22 ppm.
[0011] This invention provides a method for preparing electrolytic copper foil, comprising the following steps:
[0012] Electrolytic copper foil is obtained by electrodepositing the electrolyte described in the above technical solution.
[0013] Preferably, the electrodeposition conditions include:
[0014] The cathode roller is made of high-purity titanium, and the anode is an IrO2-RuO2 coated titanium plate; the electrode spacing is 7.7~8.3mm.
[0015] A 52000A DC current is used, with a current density of 4950~5050A / m. 2 .
[0016] Preferably, the electrodeposition temperature is 55~58°C.
[0017] Preferably, the thickness of the electrolytic copper foil is 15~20μm.
[0018] This invention provides an additive for electrolytic copper foil, comprising polyvinylpyrrolidone (PVP). This invention also provides an electrolyte for electrolytic copper foil, comprising 9.5-10.5 ppm sodium 3-mercaptopropanesulfonate, 28-32 ppm polyethylene glycol, 88-92 g / L copper sulfate, 97-102 g / L sulfuric acid, 48-53 ppm chloride ions, and 10-40 ppm PPV. The presence of PPV as an additive in this electrolyte significantly reduces the rough grain size of the electrolytic copper foil, improving its surface smoothness and corrosion resistance. Attached Figure Description
[0019] Figure 1 SEM images of copper foils prepared with electrolytes of different PVP concentrations;
[0020] Figure 2 The rough surface electron microscope images of the electrolytic copper foils prepared for Comparative Examples 2, 3 and 4 are shown.
[0021] Figure 3 Corrosion potential and corrosion permeability diagrams of electrolytic copper foils prepared with electrolytes of different PVP concentrations. Detailed Implementation
[0022] The present invention provides an additive for electrolytic copper foil, comprising polyvinylpyrrolidone.
[0023] This invention uses polyvinylpyrrolidone as one of the additive components in the electrolyte of electrolytic copper foil: a leveling agent, which has an inhibitory effect on the grains of electrolytic copper foil, thereby improving the surface corrosion resistance.
[0024] In this invention, the molecular weight of the polyvinylpyrrolidone is 38,000 to 42,000.
[0025] The present invention also provides an electrolyte for electrolytic copper foil, comprising sodium 3-mercaptopropanesulfonate (MPSA) 9.5~10.5ppm, polyethylene glycol 28~32ppm, copper sulfate 88~92g / L, sulfuric acid 97~102g / L, chloride ions 48~53ppm and polyvinylpyrrolidone 10~40ppm.
[0026] The electrolyte for electrolytic copper foil in this invention comprises 9.5~10.5 ppm of sodium 3-mercaptopropanesulfonate, specifically 9.5 ppm, 10.0 ppm, or 10.5 ppm. The sodium 3-mercaptopropanesulfonate acts as a brightener; its molecules adsorb onto highly active areas (such as protrusions) on the cathode surface, inhibiting the reduction rate of copper ions in these areas, resulting in a smoother and brighter copper foil surface and reducing roughness and pinhole defects.
[0027] The electrolytic copper foil electrolyte of this invention includes 28-32 ppm of polyethylene glycol, specifically 28 ppm, 30 ppm, or 32 ppm; the molecular weight of the polyethylene glycol is 400. Polyethylene glycol acts as a leveling agent to improve the uniformity of the copper foil. By adsorbing onto the cathode surface, it regulates the copper deposition rate in different areas, preventing excessively rapid deposition at edges or uneven surfaces.
[0028] The electrolytic copper foil electrolyte of this invention comprises 88-92 g / L copper sulfate, specifically 88 g / L, 90 g / L, or 92 g / L. It is used to provide copper ions (Cu... 2 ⁺) is the direct source of copper deposition during the electrolysis process.
[0029] The electrolytic copper foil electrolyte of this invention comprises 97-102 g / L sulfuric acid, specifically 97 g / L, 98 g / L, 99 g / L, 100 g / L, 101 g / L, or 102 g / L. It is used to enhance the conductivity of the electrolyte, reduce the cell voltage, reduce energy consumption, and prevent Cu... 2 ⁺ Hydrolysis produces copper hydroxide precipitate; promotes Cu 2 ⁺ It exists in a free state to avoid the formation of CuSO4 complexes and ensure uniform deposition.
[0030] The electrolyte for electrolytic copper foil in this invention contains 48-53 ppm of chloride ions, specifically 48 ppm, 49 ppm, 50 ppm, 51 ppm, 52 ppm, or 53 ppm. It is used to refine the grains and form an adsorption layer on the copper surface, inhibiting excessive crystal growth, resulting in finer copper foil grains and improved ductility. It also improves surface quality by reducing defects such as pinholes and pits, and enhancing the flatness of the copper foil surface.
[0031] The electrolyte for electrolytic copper foil in this invention comprises 10-40 ppm of polyvinylpyrrolidone, specifically 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, or 40 ppm. Polyvinylpyrrolidone at an optimal concentration of 20 ppm exhibits the best grain-suppressing effect on electrolytic copper foil.
[0032] In this invention, the electrolyte for electrolytic copper foil is preferably prepared according to the following steps:
[0033] Step 1: Add copper sulfate, hydrochloric acid, and additives to deionized water to prepare an electrolyte solution according to the appropriate solubility.
[0034] The second step: The prepared electrolyte undergoes multi-stage filtration and deep purification to remove impurities from the solution, ensuring the ultra-high purity of the electrolyte and laying the foundation for high-quality copper foil.
[0035] Step 3: Mixing and Testing: The concentrations of copper ions and sulfuric acid are adjusted, and specific additives (such as chloride ions, sodium saccharin, cellulose, etc.) are added according to product performance (e.g., lithium battery copper foil requires high ductility and high modulus). After uniform mixing, it is tested again to ensure that all indicators meet the requirements.
[0036] This invention provides a method for preparing electrolytic copper foil, comprising the following steps:
[0037] Electrolytic copper foil is obtained by electrodepositing the electrolyte described in the above technical solution.
[0038] In this invention, the electrodeposition conditions include:
[0039] The cathode roller is made of high-purity titanium, and the anode is an IrO2-RuO2 coated titanium plate; the electrode spacing is 7.7~8.3mm.
[0040] It uses 52000A DC power; the current density is 4950~5050A / m 2 Specifically, 4950 A / m 2 5000 A / m 2 Or 5050 A / m 2 .
[0041] In this invention, the electrodeposition temperature is 55~58°C.
[0042] In the process of generating electrolytic copper foil, this invention uses a metering pump to dynamically add additives to maintain the stability of the solubility of each additive in the electrolyte. Single additive solutions are prepared as follows: 10g of MPSA (or 7.5g of PEG, or 5g of PVP) is added to 50L of room temperature deionized water and stirred for 1 hour to obtain corresponding single additive solutions with concentrations of 200ppm, 150ppm, and 100ppm, respectively. The dynamic addition flow rate of MPSA during the foil formation process is 5L / h, that of PEG is 2L / h, and that of PVP is 1L / h (PVP is not added to electrolyte formulations without PVP).
[0043] The thickness of the electrolytic copper foil obtained by this invention is 15~20μm, specifically 15μm, 16μm, 17μm, 18μm, 19μm or 20μm.
[0044] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, of an additive for electrolytic copper foil, an electrolyte, and a method for preparing electrolytic copper foil provided by the present invention, should not be construed as limiting the scope of protection of the present invention.
[0045] The PVP molecular weight used in the following cases is 40,000.
[0046] Example 1
[0047] The electrolyte C comprises the following raw materials in the following mass concentrations: sodium 3-mercaptopropanesulfonate (MPSA) 10 ppm, polyethylene glycol (PEG400) 30 ppm, copper sulfate 90 g / L, sulfuric acid 100 g / L, chloride ions 50 ppm, and PVP concentration 20 ppm.
[0048] The process includes the following steps: electrodeposition in an electrolyte to obtain electrolytic copper foil. Specifically, the cathode roller used for electrodeposition is made of high-purity titanium (TA1 / TA2 grade), with a diameter of Ø2500mm and a surface roughness Ra≤0.05μm; the anode is an IrO2-RuO2 coated titanium plate, the electrode spacing is 7mm, a 52000A DC current is applied, and the current density is 5000A / m. 2 The electrodeposition temperature was 55-58℃. 18μm electrolytic copper foil was prepared in an electrolyte with a PVP concentration of 20ppm.
[0049] Comparative Example 1
[0050] The difference from Example 1 is that PVP was not added to electrolyte A; specifically, the electrolyte includes the following raw materials in the following mass concentrations: sodium 3-mercaptopropanesulfonate (MPSA) 10 ppm, polyethylene glycol (PEG) 30 ppm, copper sulfate 90 g / L, sulfuric acid 100 g / L, and chloride ions 50 ppm.
[0051] Comparative Example 2
[0052] The difference from Example 1 is that PVP was not added to the electrolyte; instead, SO (Safranin O) was added. Specifically, the electrolyte contains the following raw materials at the following mass concentrations: sodium 3-mercaptopropanesulfonate (MPSA) 10 ppm, polyethylene glycol (PEG) 30 ppm, copper sulfate 90 g / L, sulfuric acid 100 g / L, chloride ions 50 ppm, and SO 20 ppm.
[0053] Comparative Example 3
[0054] The difference from Example 1 is that PVP was not added to the electrolyte; instead, MV (methylene violet) was added. Specifically, the electrolyte contains the following raw materials at the following mass concentrations: sodium 3-mercaptopropanesulfonate (MPSA) 10 ppm, polyethylene glycol (PEG) 30 ppm, copper sulfate 90 g / L, sulfuric acid 100 g / L, chloride ions 50 ppm, and MV 20 ppm.
[0055] Comparative Example 4
[0056] The difference from Example 1 is that PVP was not added to the electrolyte; instead, JGB (Janus Green B) was added. Specifically, the electrolyte contains the following raw materials in the following mass concentrations: sodium 3-mercaptopropanesulfonate (MPSA) 10ppm, polyethylene glycol (PEG) 30ppm, copper sulfate 90g / L, sulfuric acid 100g / L, chloride ions 50ppm, and JGB 20ppm.
[0057] Example 2
[0058] The difference from Example 1 is that the concentration of PVP added to electrolyte B is different; specifically, the electrolyte includes the following raw materials in the following mass concentrations: sodium 3-mercaptopropanesulfonate (MPSA) 10 ppm, polyethylene glycol (PEG) 30 ppm, copper sulfate 90 g / L, sulfuric acid 100 g / L, chloride ions 50 ppm, and PVP 10 ppm.
[0059] Example 3
[0060] The difference from Example 1 is that the concentration of PVP added to electrolyte D is different; specifically, the electrolyte includes the following raw materials in the following mass concentrations: sodium 3-mercaptopropanesulfonate (MPSA) 10 ppm, polyethylene glycol (PEG) 30 ppm, copper sulfate 90 g / L, sulfuric acid 100 g / L, chloride ions 50 ppm, and PVP 30 ppm.
[0061] Example 4
[0062] The difference from Example 1 is that the concentration of PVP added to electrolyte E is different; specifically, the electrolyte includes the following raw materials in the following mass concentrations: sodium 3-mercaptopropanesulfonate (MPSA) 10 ppm, polyethylene glycol (PEG) 30 ppm, copper sulfate 90 g / L, sulfuric acid 100 g / L, chloride ions 50 ppm, and PVP 40 ppm.
[0063] Example 5
[0064] The difference from Example 1 is that the concentration of PVP added to electrolyte F is different; specifically, the electrolyte includes the following raw materials in the following mass concentrations: sodium 3-mercaptopropanesulfonate (MPSA) 10 ppm, polyethylene glycol (PEG) 30 ppm, copper sulfate 90 g / L, sulfuric acid 100 g / L, chloride ions 50 ppm, and PVP 50 ppm.
[0065] Figure 1 SEM images of electrolytic copper foils prepared with electrolytes of different PVP concentrations are shown. The surface characteristics of electrolytic copper foils with different PVP concentrations can be observed using electron microscopy. SEM observations of the rough surface of electrolytic copper foils with a coating thickness of 18 μm achieved by adding 0-50 ppm PVP are also shown. Figure 1As shown, in the absence of PVP, the copper foil surface exhibits small, dense peaks and valleys in the presence of brightener MPSA, leveling agent PEG, and chloride ions. The addition of PVP prevents copper ion electrodeposition and produces a uniform overall coating thickness. However, even with 30 ppm PEG added to electrolyte A, a uniform layer without protrusions and depressions could not be formed. In electrolyte B, protrusions or depressions were observed when 10 ppm PVP was added. This is attributed to the function of PVP as a leveling agent. PVP preferentially adsorbs onto the protruding areas of the coating, prior to the promoter MPSA and leveling agent PEG, effectively smoothing the coating. Therefore, it is speculated that even a small amount of PVP, such as 10 ppm, contributes to surface uniformity. Smooth coating surfaces were also observed in electrolyte C with 20 ppm PVP and electrolyte D with 30 ppm PVP. This phenomenon can be attributed to the selective adsorption of PVP on protruding areas, leading to electroplating starting from the valleys towards the protrusions, thus ensuring uniform coverage across the entire surface. Therefore, previous studies have also achieved smooth plating surfaces by adding PVP. However, in electrolyte E, agglomeration was observed on the plating surface after adding 40 ppm PVP. Surface agglomeration occurs when the amount of smoothing agent added exceeds a certain threshold, causing the plating surface to become uneven. In electrolyte F with 50 ppm PVP, the plating agglomeration phenomenon was further exacerbated. Excessive PVP addition leads to uneven plating surfaces. When the amount of leveling agent is excessive, it dominates in competition with the accelerator and leveling agent. Therefore, the amount of leveling agent adsorbed on the copper plating surface is increased, thereby reducing the area available for brightener deposition. This phenomenon hinders the adsorption of MPSA in the valleys where copper plating should be promoted, which inhibits crystal growth. In addition, a relatively large amount of accelerator is adsorbed in areas that excessively promote crystal growth, resulting in agglomeration and unevenness. During electroplating, the brightener MPSA and the leveling agent PEG are adsorbed on the cathode surface before copper ions. Specifically, PEG is adsorbed on prominent electroplating surface areas before copper ions and MPSA.
[0066] Figure 2 The images shown are rough-surface electron microscope (SEM) images of the electrolytic copper foils prepared in Comparative Examples 2, 3, and 4. In Comparative Example 2, A is a rough-surface electron microscope (SEM) image of the electrolytic copper foil prepared in Comparative Example 2, B is a rough-surface electron microscope (SEM) image of the electrolytic copper foil prepared in Comparative Example 2, and C is a rough-surface electron microscope (SEM) image of the electrolytic copper foil prepared in Comparative Example 3. Figure 2 Electron microscopy revealed the surface characteristics of different additives on the same electrolytic copper foil. JGB showed better results in improving the smoothness of the copper foil surface, while MV at a concentration of 20 ppm had a poorer smoothing effect, and SO at 20 ppm had the worst effect. However, compared to PVP at a concentration of 20 ppm, the smoothness of the copper foil surface was significantly worse, clearly inferior to that of PVP.
[0067] This invention calculates corrosion permeability using the following formula:
[0068] Corrosion permeability (CPR, μm / year) = (0.327 M × i corr ) / ( m × ρ);
[0069] Where M: atomic weight, 63.54 (g / mol);
[0070] i corr Current density (mA / cm²) 2 );
[0071] m: valence state, +2;
[0072] ρ: Density, 8.92 g / cm³ 3 ;
[0073] The corrosion potential, corrosion permeability, and roughness test results of the examples and comparative examples are shown in Table 1:
[0074] Table 1
[0075]
[0076] Figure 3 Corrosion potential and corrosion permeability diagrams of electrolytic copper foils prepared with electrolytes of different PVP concentrations; Figure 3 It can be seen that the corrosion potential of electrolyte A without PVP is relatively high, reaching -580mV. When the PVP concentration increases to 20 ppm, the corrosion potential (negative potential) decreases significantly to -637mV, indicating improved corrosion resistance. However, it was observed that when the PVP addition exceeds 20 ppm to 50 ppm, the corrosion potential gradually increases from -637mV to -576mV. According to the corrosion theory of copper foil, the smaller the grain size, the larger the grain boundary area; therefore, the corrosion resistance decreases, and localized corrosion (such as pitting and crevice corrosion) is affected by the grain size. In this invention, after adding 20 ppm PVP, as the PVP concentration increases, the grain size decreases, and then the corrosion potential increases, which is consistent with the trend of corrosion potential change. The corrosion rate increases, which can be considered that as the grain size decreases, the corrosion resistance decreases due to the increased fraction of grain boundaries (which are high-energy regions compared to grains). The corrosion permeability of each type is very low, and the difference between each type of corrosion permeability is not significant, less than 1 μm / year, indicating that the treated copper foil has strong corrosion resistance.
[0077] As can be seen from the above embodiments, the present invention provides an additive for electrolytic copper foil, including polyvinylpyrrolidone (PVP). The present invention also provides an electrolyte for electrolytic copper foil, comprising 9.5-10.5 ppm sodium 3-mercaptopropanesulfonate, 28-32 ppm polyethylene glycol, 88-92 g / L copper sulfate, 97-102 g / L sulfuric acid, 48-53 ppm chloride ions, and 10-40 ppm PPV. The presence of PPV as an additive in this electrolyte significantly reduces the rough grain size of the electrolytic copper foil, improving its surface smoothness and corrosion resistance. Experimental results show that the roughness of the electrolytic copper foil is 1.8-4.0 μm; the corrosion potential is -576 to -637 mV; and the corrosion penetration rate is 0.2-0.9 μm / year.
[0078] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. An additive for electrolytic copper foil, characterized in that, Including polyvinylpyrrolidone.
2. The additive for electrolytic copper foil according to claim 1, characterized in that, The molecular weight of polyvinylpyrrolidone is 38,000 to 42,000.
3. An electrolyte for electrolytic copper foil, characterized in that, It includes sodium 3-mercaptopropanesulfonate 9.5~10.5ppm, polyethylene glycol 28~32ppm, copper sulfate 88~92g / L, sulfuric acid 97~102g / L, chloride ions 48~53ppm and polyvinylpyrrolidone 10~40ppm.
4. The electrolyte for electrolytic copper according to claim 3, characterized in that, Sodium 3-mercaptopropanesulfonate 10 ppm, polyethylene glycol 30 ppm, copper sulfate 90 g / L, sulfuric acid 100 g / L, chloride ions 50 ppm.
5. The electrolyte according to claim 3, characterized in that, The polyvinylpyrrolidone content is 15-25 ppm.
6. The electrolyte according to claim 3, characterized in that, The polyvinylpyrrolidone content is 20-22 ppm.
7. A method for preparing electrolytic copper foil, comprising the following steps: Electrolytic copper foil is obtained by electrodepositing the electrolyte according to any one of claims 3 to 6.
8. The preparation method according to claim 7, characterized in that, The electrodeposition conditions include: The cathode roller is made of high-purity titanium, and the anode is an IrO2-RuO2 coated titanium plate; the electrode spacing is 7.7~8.3mm. A 52000A DC current is used, with a current density of 4950~5050A / m. 2 .
9. The preparation method according to claim 8, characterized in that, The electrodeposition temperature is 55~58℃.
10. The preparation method according to claim 7, characterized in that, The thickness of the electrolytic copper foil is 15~20μm.