Anti-oxidation treatment method for high-purity copper

Abstract

The invention provides an anti-oxidation treatment method for high-purity copper, which comprises the following steps: washing high-purity electrolytic copper by using an organic solvent after the high-purity electrolytic copper is cleaned; after washing, the high-purity electrolytic copper is sequentially subjected to drying blowing and inert gas blowing; after the purging, the high-purity electrolytic copper is subjected to standing; and the high-purity electrolytic copper is sequentially subjected to first vacuum packaging and second vacuum packaging. According to the method provided by the invention, the problem of oxidation caused by water molecule enrichment due to rough surface of the high-purity electrolytic copper is solved through a physical treatment means, a physical anti-oxidation barrier is formed, long-time non-oxidation storage of the high-purity electrolytic copper is realized, the retention period reaches more than 6 months, the influence of a drying agent and a chemical reagent on the purity of the high-purity copper is avoided, and the service life of the high-purity copper is prolonged. The method has great industrial application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrometallurgy, and particularly relates to an anti-oxidation treatment method for high-purity copper. Background Art

[0002] High-purity copper (purity ≥ 99.999%, i.e., above 5N) is an indispensable key material in the field of cutting-edge technology, and its application scenarios cover strategic industries such as the electronics industry, new energy, national defense, and aerospace. In the electronics field, high-purity copper is the core raw material for integrated circuit bonding wires, high-end PCB copper clad laminates, and high-fidelity audio and video conductors. Its conductivity and signal transmission stability directly determine the performance limit of electronic devices. In the nuclear energy and aerospace fields, due to its excellent thermal conductivity and radiation resistance, high-purity copper is used in extreme environment components such as nuclear reactor cooling pipelines and rocket engine combustion chamber linings. However, the extremely high purity of high-purity copper also makes its surface extremely active, and it is prone to react with oxygen, water vapor, and environmental pollutants during storage, generating compounds such as cuprous oxide (Cu 2 O) or copper sulfide (CuS), resulting in a decrease in conductivity, deterioration of welding performance, and even microstructural defects, severely restricting the reliability of its industrial applications.

[0003] In the process of preparing high-purity copper by electrodeposition, due to the difference in the growth rate of cathode copper grains, the microscopic morphology of the electrolytic copper surface presents uneven grain boundary protrusions and a network of microcracks. This rough surface not only increases the specific surface area but also forms local water molecule enrichment areas, and residual water is more easily adsorbed inside the microcracks (even difficult to completely remove after cleaning). Under the fluctuation of environmental temperature and humidity, these trace amounts of water interact synergistically with oxygen and carbon dioxide to gradually form basic copper carbonate (Cu 2 (OH) 2 CO 3 ), initially only forming a nanoscale oxide film that is invisible to the naked eye. However, over time, the oxidation reaction continues to spread, and the surface color gradually deepens from light yellow to brownish-black, ultimately resulting in a significant deterioration of the electrical conductivity of the material.

[0004] Traditional treatment technologies have significant limitations. For example, CN112853341A discloses a cleaning and anti-oxidation process for the surface treatment of copper foil for printed circuit boards, including: degreasing, multiple water washes, micro-etching, pickling, anti-oxidation treatment, suction drying, dry board, and other treatment steps. CN114908354A discloses a surface treatment method for soft brass wire, including pickling, one water wash, saponification liquid neutralization, two water washes, and drying treatment in an organic solvent. The organic solvent ratio is ethyl acetate, benzotriazole, dilauryl thiodipropionate, tert-butyl hydroquinone, and alkyl mercaptan.

[0005] Residual moisture or organic solvents in the conventional cleaning and drying process will accelerate the process of electrochemical corrosion. More critically, due to the strict purity requirements of high-purity electrolytic copper, it is prohibited to add passivators (such as benzotriazole) or desiccants (such as silica gel) during the cleaning and packaging process to avoid introducing exogenous impurities. This makes the control of surface oxidation completely dependent on physical isolation means, and it is difficult for existing technologies to completely block microscopic water molecules and oxygen without chemical assistance.

[0006] Therefore, developing a physical treatment method that can build a long-term antioxidant barrier has become the core requirement for breaking through the bottleneck of the industrial application of high-purity copper. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide an anti-oxidation treatment method for high-purity copper, which uses physical means to perform anti-oxidation treatment on high-purity electrolytic copper, enabling it to be stored without oxidation for a long time and ensuring the use performance of high-purity copper.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] The present invention provides an anti-oxidation treatment method for high-purity copper, and the anti-oxidation treatment method includes the following steps:

[0010] (1) After cleaning the high-purity electrolytic copper, wash it with an organic solvent;

[0011] (2) After the washing, blow-dry and purge the high-purity electrolytic copper with an inert gas in sequence;

[0012] (3) After the purging, let the high-purity electrolytic copper stand;

[0013] (4) Vacuum-pack the high-purity electrolytic copper in sequence with a first vacuum packaging and a second vacuum packaging.

[0014] The method provided by the present invention solves the problem that the rough surface of high-purity electrolytic copper generates water molecule enrichment and causes oxidation through physical means such as surface treatment, standing, and packaging, and forms a physical antioxidant barrier, achieving long-term oxidation-free storage of high-purity electrolytic copper with a retention period of more than 6 months, and avoiding the influence of desiccants and chemical reagents on the purity of high-purity copper.

[0015] In the present invention, the purity of the high-purity electrolytic copper is ≥5N.

[0016] Preferably, the organic solvent in step (1) includes ethanol and / or isopropanol.

[0017] Preferably, the washing time in step (1) is 3 - 5 seconds, for example, it can be 3 seconds, 3.5 seconds, 4 seconds, 4.5 seconds, or 5 seconds, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0018] Preferably, the cleaning in step (1) includes cleaning with acid and water.

[0019] Preferably, the acid used for cleaning includes any one or a combination of at least two of nitric acid, hydrochloric acid, or sulfuric acid. Typical but non-limiting combinations include a combination of nitric acid and hydrochloric acid, a combination of hydrochloric acid and sulfuric acid, a combination of nitric acid and sulfuric acid, or a combination of nitric acid, hydrochloric acid, and sulfuric acid.

[0020] Preferably, the concentration of the acid is 30-40%, for example, it can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0021] Preferably, the temperature of the gas for drying and blowing in step (2) is 80-100 °C, for example, it can be 80 °C, 85 °C, 90 °C, 95 °C, or 100 °C, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0022] Preferably, the angle between the direction of drying and blowing in step (2) and the plane to be dried and blown is 30-70°, for example, it can be 30°, 40°, 50°, 60°, or 70°, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0023] Preferably, the time for drying and blowing in step (2) is 10-20 seconds, for example, it can be 10 seconds, 12 seconds, 14 seconds, 15 seconds, 16 seconds, 18 seconds, or 20 seconds, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0024] Preferably, the inert gas in step (2) includes nitrogen and / or helium.

[0025] Preferably, the time for purging in step (2) is 5-10 seconds, for example, it can be 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds, or 10 seconds, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0026] Preferably, the environmental humidity for standing in step (3) is 10-30%, for example, it can be 10%, 15%, 20%, 25%, or 30%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0027] Preferably, the environmental temperature for standing in step (3) is 10-20 °C, for example, it can be 10 °C, 12 °C, 14 °C, 15 °C, 16 °C, 18 °C, or 20 °C, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0028] Preferably, the standing time in step (3) is 2 - 4 hours. For example, it can be 2 hours, 2.5 hours, 3 hours, 3.5 hours or 4 hours, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0029] Preferably, the anti - oxidation treatment method further includes: performing an appearance inspection on the high - purity electrolytic copper before the first vacuum packaging, and selecting the high - purity electrolytic copper with no oxidation on the surface.

[0030] Preferably, the material for the first vacuum packaging in step (4) includes polyamide film and / or polyamide composite film.

[0031] Preferably, the thickness of the material for the first vacuum packaging in step (4) is 18 - 22 filaments. For example, it can be 18 filaments, 19 filaments, 20 filaments, 21 filaments or 22 filaments, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0032] Preferably, the vacuum degree of the first vacuum packaging in step (4) is 0.001 - 0.01 atm. For example, it can be 0.001 atm, 0.002 atm, 0.003 atm, 0.004 atm, 0.005 atm, 0.006 atm, 0.007 atm, 0.008 atm, 0.009 atm or 0.01 atm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0033] Preferably, the material for the second vacuum packaging in step (4) includes polyester film and / or polyester composite film.

[0034] Preferably, the thickness of the material for the second vacuum packaging in step (4) is 15 - 22 filaments. For example, it can be 15 filaments, 16 filaments, 18 filaments, 20 filaments or 22 filaments, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0035] Preferably, the vacuum degree of the second vacuum packaging in step (4) is 0.001 - 0.01 atm. For example, it can be 0.001 atm, 0.002 atm, 0.003 atm, 0.004 atm, 0.005 atm, 0.006 atm, 0.007 atm, 0.008 atm, 0.009 atm or 0.01 atm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0036] As a preferred technical solution of the anti - oxidation treatment method provided by the present invention, the anti - oxidation treatment method includes the following steps:

[0037] (1) After cleaning high-purity electrolytic copper successively with acid and pure water, it is shaken and washed in anhydrous ethanol with a concentration greater than 98% and / or isopropyl alcohol with a concentration greater than 99% for 3 - 5 seconds;

[0038] (2) Use hot air at 80 - 100 °C to blow-dry the high-purity electrolytic copper at an angle of 30 - 70° with the surface of the high-purity electrolytic copper. The blowing time for each surface is 10 - 20 seconds, and then use nitrogen and / or helium to purge the high-purity electrolytic copper. The purging time for each surface is 5 - 10 seconds;

[0039] (3) Place the high-purity electrolytic copper in a purification chamber. The temperature of the purification chamber is 10 - 20 °C, and the humidity of the purification chamber is 10 - 30%. Place it for 2 - 4 hours;

[0040] (4) Conduct an appearance inspection on the high-purity electrolytic copper, and select products with no oxidation on the surface for packaging. The packaging includes: first, vacuum-pack the high-purity electrolytic copper using a polyamide film and / or polyamide composite film with a film thickness of 18 - 22 filaments, and the vacuum degree is 0.001 - 0.01 atm. Then, vacuum-pack the high-purity electrolytic copper for the second time using a polyester film and / or polyester composite film with a film thickness of 15 - 22 filaments, and the vacuum degree is 0.001 - 0.01 atm.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] The method provided by the present invention solves the problem that the rough surface of high-purity electrolytic copper causes water molecule enrichment and leads to oxidation through physical treatment means, and forms a physical antioxidant barrier, realizing long-term oxidation-free storage of high-purity electrolytic copper. The preservation period reaches more than 6 months, avoiding the influence of desiccants and chemical reagents on the purity of high-purity copper, and having great industrial application value. Specific embodiments

[0043] The technical solutions of the present invention will be further described below through specific embodiments.

[0044] Example 1

[0045] This example provides an anti-oxidation treatment method for high-purity copper. The anti-oxidation treatment method includes the following steps:

[0046] (1) After successively cleaning an electrolytic copper plate with a purity of 5N with 35% nitric acid and pure water, it is placed in 99% anhydrous ethanol and shaken and washed for 4 seconds;

[0047] (2) Use hot air at 90 °C to blow-dry the surface of the electrolytic copper plate at an angle of 50° with the surface of the electrolytic copper plate. The blowing time for each surface is 15 seconds;

[0048] (3) Purge the electrolytic copper plate with nitrogen with a purity of 99.9% for 8 seconds on each surface;

[0049] (4) Let the electrolytic copper plate stand in the purification chamber, control the temperature of the purification chamber to be 15°C and the humidity to be 15%, and let it stand for 3 hours;

[0050] (5) Conduct an appearance inspection on the electrolytic copper plate and select the electrolytic copper plate with no oxidation on the surface;

[0051] (6) Use a polyamide film (PA film) with a film thickness of 20 filaments to conduct the first-layer vacuum packaging on the electrolytic copper plate selected in step (5), and the packaging vacuum degree is 0.005 atm;

[0052] (7) Use a polyester film (PET film) with a film thickness of 18 filaments to conduct the second-layer vacuum packaging on the electrolytic copper plate with the first layer packaged, and the packaging vacuum degree is 0.005 atm.

[0053] Example 2

[0054] This example provides an anti-oxidation treatment method for high-purity copper, and the anti-oxidation treatment method includes the following steps:

[0055] (1) After washing the electrolytic copper plate with a purity of 5N successively with nitric acid with a concentration of 35% and pure water, place it in anhydrous ethanol with a concentration of 99% and shake it for washing for 3 seconds;

[0056] (2) Use hot air at 80°C to blow-dry the surface of the electrolytic copper plate at an angle of 70° with the surface of the electrolytic copper plate, and the blowing time for each surface is 20 seconds;

[0057] (3) Purge the electrolytic copper plate with nitrogen with a purity of 99.9% for 5 seconds on each surface;

[0058] (4) Let the electrolytic copper plate stand in the purification chamber, control the temperature of the purification chamber to be 20°C and the humidity to be 10%, and let it stand for 4 hours;

[0059] (5) Conduct an appearance inspection on the electrolytic copper plate and select the electrolytic copper plate with no oxidation on the surface;

[0060] (6) Use a polyamide film (PA film) with a film thickness of 22 filaments to conduct the first-layer vacuum packaging on the electrolytic copper plate selected in step (5), and the packaging vacuum degree is 0.001 atm;

[0061] (7) Use a polyester film (PET film) with a film thickness of 15 filaments to conduct the second-layer vacuum packaging on the electrolytic copper plate with the first layer packaged, and the packaging vacuum degree is 0.01 atm.

[0062] Example 3

[0063] This embodiment provides an anti-oxidation treatment method for high-purity copper. The anti-oxidation treatment method includes the following steps:

[0064] (1) After sequentially cleaning the electrolytic copper plate with a purity of 5N with nitric acid with a concentration of 35% and pure water, place it in anhydrous ethanol with a concentration of 99% and shake and wash for 5 seconds;

[0065] (2) Use hot air at 100 °C to blow-dry the surface of the electrolytic copper plate at an angle of 30° with the surface of the electrolytic copper plate, and the blowing time for each surface is 10 seconds;

[0066] (3) Use nitrogen with a purity of 99.9% to purge the electrolytic copper plate, and purge each surface for 10 seconds;

[0067] (4) Let the electrolytic copper plate stand still in the purification room, control the temperature of the purification room to be 10 °C, the humidity to be 30%, and let it stand still for 2 hours;

[0068] (5) Conduct an appearance inspection on the electrolytic copper plate and select the electrolytic copper plate without oxidation on the surface;

[0069] (6) Use a polyamide film (PA film) with a film thickness of 18 filaments to conduct the first-layer vacuum packaging on the electrolytic copper plate selected in step (5), and the packaging vacuum degree is 0.01 atm;

[0070] (7) Use a polyester film (PET film) with a film thickness of 22 filaments to conduct the second-layer vacuum packaging on the electrolytic copper plate packaged in the first layer, and the packaging vacuum degree is 0.001 atm.

[0071] Example 4

[0072] This embodiment provides an anti-oxidation treatment method for high-purity copper. Compared with Example 1, the blowing angle in step (2) is set to be perpendicular to the surface of the electrolytic copper plate, that is, the angle with the surface of the electrolytic copper plate is 90°, and the rest are the same as in Example 1.

[0073] Example 5

[0074] This embodiment provides an anti-oxidation treatment method for high-purity copper. Compared with Example 1, the blowing uses normal-temperature gas in step (2), that is, the temperature of the blowing gas is 30 °C, and the rest are the same as in Example 1.

[0075] Example 6

[0076] This embodiment provides an anti-oxidation treatment method for high-purity copper. Compared with Example 1, the materials used for vacuum packaging in steps (6) and (7) are swapped, that is, the first-layer vacuum packaging uses a polyester film (PET film), and the second-layer vacuum packaging uses a polyamide film (PA film), and the rest are the same as in Example 1.

[0077] Comparative Example 1

[0078] This comparative example provides a method for treating high-purity copper. The treatment method includes the following steps:

[0079] The high-purity electrolytic copper is washed with pure water and then dried at 50°C, and then placed in a natural state.

[0080] Comparative Example 2

[0081] This comparative example provides a method for treating high-purity copper. The treatment method includes the following steps:

[0082] The high-purity electrolytic copper is washed with pure water and then dried at 50°C, and then vacuum-packed using a polyester film (PET film).

[0083] Comparative Example 3

[0084] This comparative example provides an anti-oxidation treatment method for high-purity copper. Compared with Example 1, the blowing in step (2) is not carried out, and the rest are the same as in Example 1.

[0085] Comparative Example 4

[0086] This comparative example provides an anti-oxidation treatment method for high-purity copper. Compared with Example 1, the purging in step (3) is not carried out, and the rest are the same as in Example 1.

[0087] Comparative Example 5

[0088] This comparative example provides an anti-oxidation treatment method for high-purity copper. Compared with Example 1, the standing in step (4) is not carried out, and the rest are the same as in Example 1.

[0089] Comparative Example 6

[0090] This comparative example provides an anti-oxidation treatment method for high-purity copper. Compared with Example 1, the first-layer vacuum packaging in step (6) is not carried out, and the rest are the same as in Example 1.

[0091] The oxygen content in the high-purity copper treated in the examples and comparative examples is measured by X-ray fluorescence spectroscopy (XRF) at the 3rd month, 6th month, 7th month, and 8th month after treatment to illustrate its oxidation situation. The obtained results are listed in Table 1.

[0092] Table 1

[0093]

[0094]

[0095] As can be seen from Table 1, the anti-oxidation treatment method provided by the present invention realizes the anti-oxidation storage of high-purity electrolytic copper through surface treatment and encapsulation process, and the storage period is more than 6 months, ensuring the good use performance of high-purity electrolytic copper.

[0096] Compared with Example 1, in Examples 4 and 5, after adjusting the drying and blowing angle and temperature, it is difficult to completely remove the enriched water molecules remaining microscopically on the surface of electrolytic copper, resulting in slight oxidation after long-term placement; in Example 6, compared with the PET film, the PA film has better hygroscopicity, and the PET film has better water vapor barrier property. Exchanging the PA film with the PET film affects the water vapor permeability and barrier effect, and the anti-oxidation effect decreases.

[0097] Compared with Example 1, in the comparative example, only drying, single packaging or lacking any one treatment step, the treatment effect deteriorates significantly. It can be seen that the process steps of the treatment method of the present invention are crucial for the oxidation treatment and storage of high-purity copper and are indispensable.

[0098] In summary, the method provided by the present invention solves the problem of oxidation caused by the enrichment of water molecules on the surface of high-purity electrolytic copper due to surface roughness through physical treatment means, forms a physical anti-oxidation barrier, realizes the long-term oxidation-free storage of high-purity electrolytic copper, and the storage period reaches more than 6 months, avoiding the influence of desiccants and chemical reagents on the purity of high-purity copper, and has great industrial application value.

[0099] The specific embodiments described above further elaborate on the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for anti-oxidation treatment of high-purity copper, characterized in that: The anti-oxidation treatment method comprises the following steps: (1) After cleaning the high-purity electrolytic copper, washing it with an organic solvent; (2) After the washing, the high-purity electrolytic copper is sequentially dried and purged with an inert gas; (3) After the purging, the high-purity electrolytic copper is allowed to stand; (4) The high-purity electrolytic copper is subjected to a first vacuum packaging and a second vacuum packaging in sequence.

2. The anti-oxidation treatment method according to claim 1, characterized in that: The organic solvent in step (1) comprises ethanol and / or isopropanol; Preferably, the washing time in step (1) is 3-5 seconds; Preferably, the cleaning in step (1) comprises cleaning with acid and water.

3. The anti-oxidation treatment method according to claim 1 or 2, characterized in that: The temperature of the gas used in step (2) is 80-100°C; Preferably, the angle between the drying and blowing direction in step (2) and the drying and blowing plane is 30-70°; Preferably, the drying and blowing time in step (2) is 10-20 seconds.

4. The anti-oxidation treatment method according to any one of claims 1 to 3, characterized in that: The inert gas in step (2) includes nitrogen and / or helium; Preferably, the purging time in step (2) is 5-10 seconds.

5. The anti-oxidation treatment method according to any one of claims 1 to 4, characterized in that: The humidity of the static environment in step (3) is 10-30%; Preferably, the ambient temperature of the static state in step (3) is 10-20°C.

6. The anti-oxidation treatment method according to any one of claims 1 to 5, characterized in that: The standing time in step (3) is 2-4 hours.

7. The anti-oxidation treatment method according to any one of claims 1 to 6, characterized in that: The anti-oxidation treatment method further comprises: performing an appearance inspection on the high-purity electrolytic copper before the first vacuum packaging, and selecting high-purity electrolytic copper with no oxidation on the surface.

8. The anti-oxidation treatment method according to any one of claims 1 to 7, characterized in that: Step (4) the material of the first vacuum packaging includes a polyamide film and / or a polyamide composite film; Preferably, the thickness of the first vacuum-packed material in step (4) is 18-22 filaments; Preferably, the vacuum degree of the first vacuum packaging in step (4) is 0.001-0.01atm.

9. The anti-oxidation treatment method according to any one of claims 1 to 8, characterized in that: Step (4) the material of the second vacuum packaging includes a polyester film and / or a polyester composite film; Preferably, the thickness of the second vacuum-packed material in step (4) is 15-22 filaments; Preferably, the vacuum degree of the second vacuum packaging in step (4) is 0.001-0.01atm.

10. The anti-oxidation treatment method according to any one of claims 1 to 9, characterized in that: The anti-oxidation treatment method comprises the following steps: (1) After the high-purity electrolytic copper is washed with acid and pure water in sequence, it is shaken and washed for 3-5 seconds in anhydrous ethanol with a concentration greater than 98% and / or isopropanol with a concentration greater than 99%; (2) using hot air at 80-100°C to dry the high-purity electrolytic copper at an angle of 30-70° to the surface of the high-purity electrolytic copper, and the drying time for each surface is 10-20 seconds, and then using nitrogen and / or helium to purge the high-purity electrolytic copper, and the purge time for each surface is 5-10 seconds; (3) placing the high-purity electrolytic copper in a clean room at a temperature of 10-20° C. and a humidity of 10-30% for 2-4 hours; (4) Performing an appearance inspection on the high-purity electrolytic copper and selecting products without surface oxidation for packaging, wherein the packaging comprises: firstly performing a first layer of vacuum packaging on the high-purity electrolytic copper, wherein the first layer of vacuum packaging uses a polyamide film and / or a polyamide composite film with a film thickness of 18-22 filaments and a vacuum degree of 0.001-0.01 atm, and then performing a second layer of vacuum packaging on the high-purity electrolytic copper, wherein the second layer of vacuum packaging uses a polyester film and / or a polyester composite film with a film thickness of 15-22 filaments and a vacuum degree of 0.001-0.01 atm.

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