A chromium-free oxidation prevention method for electrolytic copper foil

Abstract

The present application belongs to the technical field of electrolytic copper foil, and provides a chromium-free anti-oxidation method for electrolytic copper foil, which solves the problem of copper foil oxidation under chromium-free condition. The electrolytic copper foil is sequentially subjected to pickling, roughening I, roughening II, electroplating, passivation, silane coupling and drying to complete the treatment of the electrolytic copper foil. In the process of treating the copper foil, a Ni-Cu-Sn alloy layer is deposited on the surface of the copper foil through a specific composition of electroplating solution, so as to achieve the purpose of preliminary protection. Then, passivation is carried out in a passivation solution, and the passivation solution can effectively form an organic adsorption film to inhibit the oxidation of the electrolytic copper foil. On the basis of abandoning the addition of chromate, the present application can still well improve the anti-oxidation property of the electrolytic copper foil, and there is no oxidation discoloration under high-temperature and high-humidity conditions, and the electrolytic copper foil is resistant to chemical reagents, and the tensile strength under high temperature reaches 406 MPa, and has excellent mechanical properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrolytic copper foil, and particularly relates to a chromium-free anti-oxidation method for electrolytic copper foil. BACKGROUND

[0002] Electrolytic copper foil is an important material for manufacturing copper-clad plate, printed circuit board and lithium ion battery. With the rapid development of electronic information, the demand for electrolytic copper foil is increasing. In the production, storage and transportation of a large amount of electrolytic copper foil, it is found that the surface of the electrolytic copper foil is damaged and corroded due to changes in the environment (such as changes in humidity and temperature), friction of the contact surface (such as ground contact and collision) and corrosion of organic liquids (such as fingerprints and sweat), and the degree of oxidation is rapidly increased, thereby causing the performance of the copper foil to decrease. In order to solve the above problems, more and more manufacturers have begun to study the surface protection technology of electrolytic copper foil. At present, the most effective and widely used technology is to plate a layer of chromium on the surface of the copper foil. This chromium plating technology can greatly improve the surface performance of the copper foil, thereby achieving the purpose of protection. However, with the development of environmental protection, it is found that chromium can cause irreparable damage to the environment and human body, so the use of chromium salt is also on the agenda. Therefore, there is an urgent need for a protection process for electrolytic copper foil. SUMMARY

[0003] The present application aims to overcome the problems in the prior art and provide a chromium-free anti-oxidation method for electrolytic copper foil.

[0004] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0005] The present application provides a chromium-free anti-oxidation method for electrolytic copper foil, comprising the following steps:

[0006] The electrolytic copper foil is sequentially subjected to acid pickling, roughening I, roughening II, electroplating, passivation, silane coupling and drying to complete the treatment of the electrolytic copper foil.

[0007] Preferably, the acid pickling is carried out in a sulfuric acid solution, and the concentration of the sulfuric acid solution is 200-230 g / L.

[0008] The temperature of the acid pickling is 30-40℃, and the time is 30-40 s.

[0009] Preferably, the roughening I is carried out in a roughening I solution, and the concentration of copper sulfate in the roughening I solution is 60-70 g / L, and the concentration of sulfuric acid is 170-180 g / L.

[0010] The current density of the roughening I is 20-70 A / dm 2 , the temperature is 25-35℃, and the time is 6-10 s.

[0011] Preferably, the roughening II is carried out in a roughening II solution with a copper sulfate concentration of 90-110 g / L and a sulfuric acid concentration of 140-160 g / L;

[0012] The current density of the roughening II is 30-50 A / dm 2 , the temperature is 25-35℃, and the time is 10-15 s.

[0013] Preferably, the plating is carried out in a plating solution with a nickel sulfate concentration of 30-40 g / L, a copper sulfate concentration of 20-30 g / L, a tin tetrachloride concentration of 10-15 g / L, and a potassium pyrophosphate concentration of 50-60 g / L.

[0014] Preferably, the current density of the plating is 40-60 A / dm 2 , the temperature is 30-40℃, and the time is 10-15 s.

[0015] Preferably, the passivation is carried out in a passivation solution with a sodium citrate concentration of 10-15 g / L, a tartaric acid concentration of 10-15 g / L, a mercaptoacetic acid concentration of 1-5 g / L, and a sodium molybdate concentration of 20-23 g / L.

[0016] Preferably, the current density of the passivation is 8-15 A / dm 2 , the temperature is 20-30℃, and the time is 10-20 s.

[0017] Preferably, the silane coupling is carried out in a coupling solution with a volume ratio of KH550, propyltrimethoxysilane, and water of 1-1.5:0.6-0.8:2.5-3.5.

[0018] The temperature of the silane coupling is 20-30℃, and the time is 4-6 s.

[0019] Preferably, the temperature of the drying is 120-150℃, and the time is 1-1.5 h.

[0020] The present application provides a chromium-free anti-oxidation method for electrolytic copper foil, comprising the following steps: sequentially carrying out pickling, roughening I, roughening II, plating, passivation, silane coupling, and drying on the electrolytic copper foil to complete the treatment of the electrolytic copper foil. In the process of treating the copper foil, a Ni-Cu-Sn alloy layer is deposited on the surface of the copper foil by using a plating solution with a specific composition, thereby achieving the purpose of preliminary protection. Then, passivation is carried out in a passivation solution, which can effectively form an organic adsorption film to inhibit the oxidation of the electrolytic copper foil. The present application protects the electrolytic copper foil from oxidation by the combined action of multiple steps without using chromate, and has low process requirements and is suitable for large-scale processing. DETAILED DESCRIPTION

[0021] The present application provides a chromium-free anti-oxidation method for electrolytic copper foil, comprising the following steps:

[0022] The electrolytic copper foil is sequentially subjected to pickling, roughening I, roughening II, electroplating, passivation, silane coupling and drying to complete the treatment of the electrolytic copper foil.

[0023] In the present application, the pickling is carried out in a sulfuric acid solution, and the concentration of the sulfuric acid solution is preferably 200-230 g / L, further preferably 205-225 g / L, and more preferably 210-220 g / L.

[0024] In the present application, the temperature of the pickling is preferably 30-40℃, further preferably 32-38℃, and more preferably 34-36℃; and the time is preferably 30-40 s, further preferably 32-38 s, and more preferably 34-36 s.

[0025] In the present application, the roughening I is carried out in a roughening I solution, and the concentration of copper sulfate in the roughening I solution is preferably 60-70 g / L, further preferably 62-68 g / L, and more preferably 64-66 g / L; and the concentration of sulfuric acid is preferably 170-180 g / L, further preferably 172-178 g / L, and more preferably 174-176 g / L.

[0026] In the present application, the current density of the roughening I is preferably 20-70 A / dm 2 , further preferably 30-60 A / dm 2 , and more preferably 40-50 A / dm 2 ; the temperature is preferably 25-35℃, further preferably 26-34℃, and more preferably 28-32℃; and the time is preferably 6-10 s, further preferably 7-9 s, and more preferably 7.5-8.5 s.

[0027] In the present application, the roughening II is carried out in a roughening II solution, and the concentration of copper sulfate in the roughening II solution is preferably 90-110 g / L, further preferably 95-105 g / L, and more preferably 98-102 g / L; and the concentration of sulfuric acid is preferably 140-160 g / L, further preferably 145-155 g / L, and more preferably 148-152 g / L.

[0028] In the present application, the current density of the roughening II is preferably 30-50 A / dm 2 , further preferably 35-45 A / dm 2 , and more preferably 38-42 A / dm 2temperature is preferably 25 to 35°C, further preferably 26 to 34°C, and more preferably 28 to 32°C; and the time is preferably 10 to 15 seconds, further preferably 11 to 14 seconds, and more preferably 12 to 13 seconds.

[0029] In the present application, the plating is performed in a plating solution having a nickel sulfate concentration of preferably 30 to 40 g / L, further preferably 32 to 38 g / L, and more preferably 34 to 36 g / L; a copper sulfate concentration of preferably 20 to 30 g / L, further preferably 22 to 28 g / L, and more preferably 24 to 26 g / L; a tin tetrachloride concentration of preferably 10 to 15 g / L, further preferably 11 to 14 g / L, and more preferably 12 to 13 g / L; and a potassium pyrophosphate concentration of preferably 50 to 60 g / L, further preferably 52 to 58 g / L, and more preferably 54 to 56 g / L.

[0030] In the present application, the plating is performed at a current density of preferably 40 to 60 A / dm 2 , further preferably 45 to 55 A / dm 2 , and more preferably 48 to 52 A / dm 2 ; a temperature of preferably 30 to 40°C, further preferably 32 to 38°C, and more preferably 34 to 36°C; and a time of preferably 10 to 15 seconds, further preferably 11 to 14 seconds, and more preferably 12 to 13 seconds.

[0031] In the present application, the passivation is performed in a passivation solution having a sodium citrate concentration of preferably 10 to 15 g / L, further preferably 11 to 14 g / L, and more preferably 12 to 13 g / L; a tartaric acid concentration of preferably 10 to 15 g / L, further preferably 11 to 14 g / L, and more preferably 12 to 13 g / L; a mercaptoacetic acid concentration of preferably 1 to 5 g / L, further preferably 2 to 4 g / L, and more preferably 2.5 to 3.5 g / L; and a sodium molybdate concentration of preferably 20 to 23 g / L, further preferably 21 to 22 g / L, and more preferably 21.4 to 21.6 g / L.

[0032] In the present application, the passivation is performed at a current density of preferably 8 to 15 A / dm 2 , further preferably 9 to 14 A / dm 2 , and more preferably 10 to 12 A / dm 2 ; a temperature of preferably 20 to 30°C, further preferably 22 to 28°C, and more preferably 24 to 26°C; and a time of preferably 10 to 20 seconds, further preferably 12 to 18 seconds, and more preferably 14 to 16 seconds.

[0033] In the present application, the silane coupling is carried out in a coupling solution; the volume ratio of KH550, propyl trimethoxysilane and water in the coupling solution is preferably 1-1.5:0.6-0.8:2.5-3.5, further preferably 1.1-1.4:0.65-0.75:2.6-3.4, more preferably 1.2-1.3:0.68-0.72:2.8-3.2.

[0034] In the present application, the temperature of the silane coupling is preferably 20-30℃, further preferably 22-28℃, more preferably 24-26℃; the time is preferably 4-6s, further preferably 4.5-5.5s, more preferably 4.8-5.2s.

[0035] In the present application, the temperature of the drying is preferably 120-150℃, further preferably 125-145℃, more preferably 130-140℃; the time is preferably 1-1.5h, further preferably 1.1-1.4h, more preferably 1.2-1.3h.

[0036] The technical solutions provided by the present application are described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0037] Example 1

[0038] The electrolytic copper foil is placed in a sulfuric acid solution with a concentration of 210g / L, and pickled at 35℃ for 30s; then placed in roughening I solution (in which the concentration of copper sulfate is 65g / L, the concentration of sulfuric acid is 175g / L, and water is used for configuration), the current density is controlled at 50A / dm 2 , roughened at 30℃ for 10s; then placed in roughening II solution (in which the concentration of copper sulfate is 98g / L, the concentration of sulfuric acid is 150g / L, and water is used for configuration), the current density is controlled at 40A / dm 2 , roughened at 30℃ for 15s to complete roughening II; then placed in plating solution (the concentration of nickel sulfate is 35g / L, the concentration of copper sulfate is 25g / L, the concentration of tin tetrachloride is 12g / L, the concentration of potassium pyrophosphate is 55g / L, and water is used for configuration), the current density is controlled at 50A / dm 2 , and the temperature is 35℃, and plated for 10s to form an alloy layer on the surface of the copper foil; then placed in passivation solution (in which the concentration of sodium citrate is 14g / L, the concentration of tartaric acid is 12g / L, the concentration of mercaptoacetic acid is 5g / L, and the concentration of sodium molybdate is 22g / L, and water is used for configuration), the current density is controlled at 11A / dm 2, temperature 25°C for 15s; the passivated copper foil was placed in coupling solution (volume ratio of KH550, propyl trimethoxysilane and water is 1:0.8:3) at 25°C for 5s; after the coupling was completed, it was dried at 130°C for 1.5h to complete the anti-oxidation treatment of the electrolytic copper foil.

[0039] The electrolytic copper foil prepared in this example was subjected to performance test, and the results are recorded in Table 1.

[0040] Example 2

[0041] The electrolytic copper foil was placed in a sulfuric acid solution with a concentration of 200g / L and pickled at 38°C for 40s; then it was placed in roughening I solution (in which the concentration of copper sulfate is 62g / L and the concentration of sulfuric acid is 176g / L, configured with water) to control the current density at 65A / dm 2 , roughened at 33°C for 8s; then it was placed in roughening II solution (in which the concentration of copper sulfate is 95g / L and the concentration of sulfuric acid is 145g / L, configured with water) to control the current density at 35A / dm 2 , roughened at 25°C for 10s to complete roughening II; then it was placed in plating solution (in which the concentration of nickel sulfate is 38g / L, the concentration of copper sulfate is 22g / L, the concentration of tin tetrachloride is 14g / L, and the concentration of potassium pyrophosphate is 52g / L, configured with water) to control the current density at 60A / dm 2 , and plated at a temperature of 38°C for 12s to form an alloy layer on the surface of the copper foil; then it was placed in passivation solution (in which the concentration of sodium citrate is 11g / L, the concentration of tartaric acid is 14g / L, the concentration of mercaptoacetic acid is 4g / L, and the concentration of sodium molybdate is 20g / L, configured with water) to control the current density at 9A / dm 2 , passivated at a temperature of 30°C for 20s; the passivated copper foil was placed in coupling solution (volume ratio of KH550, propyl trimethoxysilane and water is 1.3:0.65:2.8) at 30°C for 6s; after the coupling was completed, it was dried at 140°C for 1.3h to complete the anti-oxidation treatment of the electrolytic copper foil.

[0042] The electrolytic copper foil prepared in this example was subjected to performance test, and the results are recorded in Table 1.

[0043] Example 3

[0044] The electrolytic copper foil was placed in a sulfuric acid solution with a concentration of 225g / L and pickled at 30°C for 35s; then it was placed in roughening I solution (in which the concentration of copper sulfate is 65g / L and the concentration of sulfuric acid is 171g / L, configured with water) to control the current density at 40A / dm 2, roughening for 6s at 26°C; then placed in a roughening II solution (in which the copper sulfate concentration is 105 g / L and the sulfuric acid concentration is 158 g / L, configured with water), and the current density is controlled at 40 A / dm 2 , roughening for 11s at 30°C, and roughening II is completed; then placed in a plating solution (in which the nickel sulfate concentration is 32 g / L, the copper sulfate concentration is 25 g / L, the tin tetrachloride concentration is 10 g / L, and the potassium pyrophosphate concentration is 60 g / L, configured with water), and the current density is controlled at 45 A / dm 2 , and the temperature is 30°C, and plating is carried out for 15s to form an alloy layer on the surface of the copper foil; then placed in a passivation solution (in which the sodium citrate concentration is 12 g / L, the tartaric acid concentration is 15 g / L, the mercaptoacetic acid concentration is 1 g / L, and the sodium molybdate concentration is 21 g / L, configured with water), and the current density is controlled at 14 A / dm 2 , and the temperature is 22°C, and passivation is carried out for 16s; the passivated copper foil is placed in a coupling solution (KH550, propyltrimethoxysilane, and water in a volume ratio of 1:0.7:3.4), and coupling is carried out for 5s at 25°C; after the coupling is completed, drying is carried out at 120°C for 1h to complete the anti-oxidation treatment of the electrolytic copper foil.

[0045] The electrolytic copper foil prepared in this example is subjected to performance testing, and the results are recorded in Table 1.

[0046] Example 4

[0047] The electrolytic copper foil is placed in a sulfuric acid solution with a concentration of 208 g / L, and pickling is carried out for 40s at 36°C; then placed in a roughening I solution (in which the copper sulfate concentration is 70 g / L and the sulfuric acid concentration is 175 g / L, configured with water), and the current density is controlled at 40 A / dm 2 , and roughening is carried out for 10s at 32°C; then placed in a roughening II solution (in which the copper sulfate concentration is 98 g / L and the sulfuric acid concentration is 152 g / L, configured with water), and the current density is controlled at 50 A / dm 2 , and roughening is carried out for 15s at 30°C to complete roughening II; then placed in a plating solution (in which the nickel sulfate concentration is 40 g / L, the copper sulfate concentration is 28 g / L, the tin tetrachloride concentration is 11 g / L, and the potassium pyrophosphate concentration is 54 g / L, configured with water), and the current density is controlled at 53 A / dm 2 , and the temperature is 40°C, and plating is carried out for 12s to form an alloy layer on the surface of the copper foil; then placed in a passivation solution (in which the sodium citrate concentration is 11 g / L, the tartaric acid concentration is 14 g / L, the mercaptoacetic acid concentration is 3 g / L, and the sodium molybdate concentration is 22 g / L, configured with water), and the current density is controlled at 12 A / dm 2, the passivation is completed at 25℃ for 18s; the passivated copper foil is placed in coupling solution (volume ratio of KH550, propyl trimethoxysilane and water is 1.2:0.8:2.7) at 28℃ for 6s; after the coupling is completed, the copper foil is dried at 145℃ for 1.2h, and the anti-oxidation treatment of the electrolytic copper foil is completed.

[0048] The electrolytic copper foil prepared in the example is subjected to performance test, and the results are recorded in Table 1.

[0049] Table 1 test results

[0050]

[0051]

[0052] It can be seen from the above examples that the present application provides a chromium-free anti-oxidation method for electrolytic copper foil, comprising the following steps: sequentially performing acid pickling, roughening I, roughening II, electroplating, passivation, silane coupling and drying on the electrolytic copper foil to complete the treatment of the electrolytic copper foil. In the process of treating the copper foil, the present application deposits a Ni-Cu-Sn alloy layer on the surface of the copper foil through a specific composition of electroplating solution, thereby achieving the purpose of preliminary protection; then passivation is performed in a passivation solution, and the passivation solution can effectively form an organic adsorption film, thereby inhibiting the oxidation of the electrolytic copper foil. On the basis of abandoning the addition of chromate, the present application can still well improve the anti-oxidation property of the electrolytic copper foil, and there is no oxidation discoloration under high temperature and high humidity conditions, and the electrolytic copper foil is resistant to chemical reagents, and the tensile strength under high temperature reaches 406MPa, having excellent mechanical properties.

[0053] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A chromium-free oxidation prevention method for electrolytic copper foil, characterized by, The method comprises the following steps: The electrolytic copper foil is sequentially subjected to acid pickling, roughening I, roughening II, electroplating, passivation, silane coupling and drying to complete the treatment of the electrolytic copper foil; The electroplating is performed in an electroplating solution, the concentration of nickel sulfate in the electroplating solution is 30-40 g / L, the concentration of copper sulfate is 20-30 g / L, the concentration of tin tetrachloride is 10-15 g / L, and the concentration of potassium pyrophosphate is 50-60 g / L; The current density of the electroplating is 40-60 A / dm 2 at a temperature of 30-40 °C for 10-15 s.

2. The method of claim 1, wherein, The acid pickling is performed in a sulfuric acid solution, the concentration of the sulfuric acid solution is 200-230 g / L; The temperature of the acid pickling is 30-40 ℃, and the time is 30-40 s.

3. The method of claim 1 or 2, wherein, The roughening I is performed in a roughening I solution, the concentration of copper sulfate in the roughening I solution is 60-70 g / L, and the concentration of sulfuric acid is 170-180 g / L; The current density of the roughening I is 20-70 A / dm 2 at a temperature of 25-35°C for 6-10 seconds.

4. The method of claim 3, wherein, The roughening II is performed in a roughening II solution, the concentration of copper sulfate in the roughening II solution is 90-110 g / L, and the concentration of sulfuric acid is 140-160 g / L; The current density of the roughening II is 30-50 A / dm 2 at a temperature of 25-35°C for 10-15 seconds.

5. The method of claim 4, wherein, The passivation is performed in a passivation solution, the concentration of sodium citrate in the passivation solution is 10-15 g / L, the concentration of tartaric acid is 10-15 g / L, the concentration of mercaptoacetic acid is 1-5 g / L, and the concentration of sodium molybdate is 20-23 g / L.

6. The method of claim 5, wherein, The current density of the passivation is 8-15 A / dm 2 at a temperature of 20-30 °C for 10-20 s.

7. The method of claim 1 or 6, wherein, The silane coupling is performed in a coupling solution, the volume ratio of KH550, propyltrimethoxysilane and water in the coupling solution is 1-1.5:0.6-0.8:2.5-3.5; The temperature of the silane coupling is 20-30 ℃, and the time is 4-6 s.

8. The method of claim 7, wherein, The temperature of the drying is 120-150 ℃, and the time is 1-1.5 h.

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