Cleaning method for high-purity electrolytic copper

Abstract

The invention relates to a cleaning method for high-purity electrolytic copper, which comprises the following steps: sequentially carrying out pretreatment, first acid pickling, first water washing, second acid pickling, second water washing, third acid pickling, third water washing, rinsing and drying on a to-be-cleaned high-purity electrolytic copper plate to obtain the high-purity electrolytic copper, wherein the pretreatment comprises sand blasting treatment and cleaning which are carried out in sequence. According to the method, part of impurities obviously existing on the surface of the high-purity electrolytic copper plate to be cleaned are removed through sand blasting treatment, then trace impurities in residual black spots, yellow traces and microcracks are removed layer by layer in a cleaning mode of pickling and washing alternate treatment, new impurities cannot be introduced in the process, and the use requirement of high-purity copper can be met; meanwhile, the cleaned acid solution can be reused, and pollution between the acid solutions is avoided; the one-time cleaning qualification rate is high, the purity and the resistivity before cleaning are still kept stable and are not obviously increased, and the storage retention period reaches more than 6 months.

Description

Technical Field

[0001] The invention relates to the field of wet purification of metallic copper, and in particular to a cleaning method for high-purity electrolytic copper. Background Art

[0002] High-purity copper refers to metallic copper with a purity of 5N (99.999%) or above. As an emerging material, high-purity copper is used in the preparation of high-purity analytical standard samples, various connecting wires in the electronics industry, bonding wires for electronic packaging, high-quality audio lines, integrated circuits, liquid crystal displays, sputtering targets, ion plating and other high-tech fields. It is also an indispensable and valuable material in the aviation, aerospace and metallurgical industries.

[0003] In the process of using high-purity copper, the impurities on its surface are required to reach the trace level, and the cleanliness requirements are extremely high. In the existing high-purity copper preparation process, electrolytic refining is usually used. Through electrolytic refining, impurities in copper can be removed, the purity of copper can be improved, and impurity elements in copper, such as iron, nickel, zinc, etc., can be effectively removed. In the electrolytic deposition process, due to the difference in grain growth rate, the surface of electrolytic copper presents a rugged morphology. This rough surface will make the electrolytic copper prone to black spots and local yellowing after cleaning and drying. There is also a risk of trace impurities remaining in microcracks, which cannot meet the use requirements of high-purity copper. Therefore, it is usually necessary to clean the surface of the copper after electrolytic deposition before use.

[0004] CN110788061A discloses a surface cleaning device and method for ultrapure copper sheets, wherein the material to be cleaned is sequentially placed in a cleaning liquid, deionized water and ethanol zone by the device, and then rotated for cleaning and taken out, wherein the cleaning liquid includes an acid solution, ethanol and water. The cleaning method described in the device focuses on controlling the cleaning process by the device, and it can only handle problems such as black shadows on the surface, and cannot completely remove trace impurities remaining in microcracks, and does not mention whether long-term storage can still meet the use standards of high-purity copper.

[0005] CN114808043A discloses a method for cleaning high-purity electrolytic copper, wherein in a cleaning tank, a high-purity electrolytic copper sheet to be cleaned is sequentially pickled and washed with water under a vibrating state, and then rinsed and dried to obtain high-purity electrolytic copper; the pickling includes sequentially primary pickling, secondary pickling and tertiary pickling; the water washing includes sequentially primary water washing, secondary water washing and tertiary water washing. Although no new impurities are introduced during the cleaning process and the storage shelf life is long, the pickling process of different concentrations is sequentially carried out, which easily leads to mixing of pickling solutions, and after multiple cleanings, the cleaning effect gradually decreases.

[0006] Therefore, how to provide a cleaning method for high-purity electrolytic copper so that the qualified rate of high-purity copper after one cleaning is high, and the surface is clean, free of oxidation marks and has a long shelf life after cleaning is a technical problem that needs to be solved urgently. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a method for cleaning high-purity electrolytic copper, which first adopts sandblasting to remove some impurities that are obviously present on the surface of the high-purity electrolytic copper plate to be cleaned, and then adopts a cleaning method of alternating acid washing and water washing to remove residual black spots, yellowing marks and trace impurities in microcracks layer by layer. This process will not introduce new impurities and can meet the use requirements of high-purity copper; at the same time, the acid solution after cleaning can be reused and will not cause pollution between acid solutions; the qualified rate of one cleaning is high, the purity before cleaning is still maintained, the resistivity is stable, there is no obvious increase, and the storage retention period is more than 6 months.

[0008] It should be noted that the "high purity" in the high-purity electrolytic copper described in the present invention refers to a purity ≥ 5N (99.999%).

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a method for cleaning high-purity electrolytic copper, the cleaning method comprising the following steps:

[0011] The high-purity electrolytic copper plate to be cleaned is sequentially subjected to pretreatment, first pickling, first water washing, second pickling, second water washing, third pickling, third water washing, rinsing and drying to obtain high-purity electrolytic copper;

[0012] Wherein, the pre-treatment includes sandblasting and washing performed in sequence.

[0013] In the present invention, sandblasting is first used to remove part of the impurities obviously existing on the surface of the high-purity electrolytic copper plate to be cleaned, and then the cleaning method of acid washing and water washing is used to remove the residual black spots, yellowing marks and trace impurities in micro cracks layer by layer. This process does not introduce new impurities and can meet the use requirements of high-purity electrolytic copper; at the same time, the acid solution after cleaning can be reused and will not cause pollution between acid solutions; the qualified rate of one cleaning can reach 95% or more, and the purity before cleaning is still maintained, the resistivity is stable and has no obvious increase, and the storage retention period is more than 6 months.

[0014] As a preferred technical solution of the present invention, the pressure of the sandblasting treatment is 0.4-0.7 MPa, such as 0.4 MPa, 0.5 MPa, 0.6 MPa or 0.7 MPa.

[0015] Preferably, the angle of the sandblasting is 60 to 80 degrees, such as 60 degrees, 65 degrees, 70 degrees, 75 degrees or 80 degrees.

[0016] Preferably, the sand material for sandblasting includes white corundum or quartz sand.

[0017] Preferably, the particle size of the sand material is 20-40 mesh, such as 20 mesh, 25 mesh, 30 mesh, 35 mesh or 40 mesh.

[0018] Preferably, the washing is performed by pure water ultrasonic washing.

[0019] Preferably, the washing time is 3 to 5 minutes, for example, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes or 5 minutes.

[0020] As a preferred technical solution of the present invention, the acid used in the first pickling comprises a mixed acid solution.

[0021] Preferably, the mixed acid solution comprises electronic grade sulfuric acid, electronic grade hydrochloric acid, electronic grade nitric acid and pure water.

[0022] Preferably, the concentration of the electronic grade sulfuric acid is 96-98wt%, for example, 96wt%, 96.5wt%, 97wt%, 97.5wt% or 98wt%.

[0023] Preferably, the concentration of the electronic grade hydrochloric acid is 30-40wt%, for example, 30wt%, 32wt%, 34wt%, 36wt%, 38wt% or 40wt%.

[0024] Preferably, the concentration of the electronic grade nitric acid is 60-70wt%, for example, 60wt%, 62wt%, 64wt%, 66wt%, 68wt% or 70wt%.

[0025] Preferably, in the mixed acid solution, the mass ratio of electronic grade sulfuric acid, electronic grade hydrochloric acid, electronic grade nitric acid and pure water is 1:1:1:(5-10), for example, 1:1:1:5, 1:1:1:6, 1:1:1:7, 1:1:1:8, 1:1:1:9 or 1:1:1:10, etc.

[0026] Preferably, the first pickling time is 180 to 200 seconds, for example, 180 seconds, 185 seconds, 190 seconds, 195 seconds or 200 seconds.

[0027] As a preferred technical solution of the present invention, the acid used in the second pickling includes a nitric acid solution.

[0028] Preferably, the nitric acid solution comprises nitric acid and pure water.

[0029] Preferably, the concentration of the nitric acid is 60-70wt%, for example, 60wt%, 62wt%, 64wt%, 66wt%, 68wt% or 70wt%.

[0030] Preferably, the mass ratio of the nitric acid to pure water is 1:(0.5-5), for example, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5, etc.

[0031] Preferably, the second pickling time is 60 to 80 s, for example, 60 s, 62 s, 64 s, 66 s, 68 s, 70 s, 72 s, 74 s, 76 s, 78 s or 80 s.

[0032] As a preferred technical solution of the present invention, the third pickling is performed by immersing in a dilute sulfuric acid solution.

[0033] In the present invention, a mixed acid solution is first used for cleaning, so that a large amount of impurities on the surface of the high-purity electrolytic copper, including oxides and compounds, can be removed. A nitric acid solution is then used for cleaning, so that residual oxides that are not cleaned by the first acid washing and trace impurities in microcracks can be removed. A dilute sulfuric acid solution is then used for immersion, so that the acid remaining in the micropores and microcracks can be removed, so as to avoid the acid existing in the micropores and microcracks for a long time, thereby affecting the purity and storage period of the high-purity electrolytic copper after cleaning, and at the same time, the surface color can be made consistent.

[0034] The present invention uses the combination of three acid solutions to perform cleaning layer by layer, thereby ensuring that impurities and dirt on the surface of high-purity electrolytic copper are cleaned, and the surface color is consistent and can be preserved for a long time.

[0035] Preferably, the concentration of the dilute sulfuric acid solution is 0.0001-0.001 mol / L, for example, 0.0001 mol / L, 0.0002 mol / L, 0.0003 mol / L, 0.0004 mol / L, 0.0005 mol / L, 0.0006 mol / L, 0.0007 mol / L, 0.0008 mol / L, 0.0009 mol / L or 0.001 mol / L, etc.

[0036] Preferably, the immersion time of the third pickling is 4 to 6 hours, for example, 4 hours, 4.5 hours, 5 hours, 5.5 hours or 6 hours.

[0037] As a preferred technical solution of the present invention, the water used in the first water washing, the second water washing and the third water washing each independently comprises pure water.

[0038] Preferably, the first water washing time is 30 to 60 s, for example, 30 s, 35 s, 40 s, 45 s, 50 s, 55 s or 60 s.

[0039] Preferably, the second water washing time is 10 to 30 seconds, for example, 10 seconds, 15 seconds, 20 seconds, 25 seconds or 30 seconds.

[0040] Preferably, the third water washing time is 30 to 60 s, for example, 30 s, 35 s, 40 s, 45 s, 50 s, 55 s or 60 s.

[0041] As a preferred technical solution of the present invention, the rinsing is carried out in anhydrous ethanol.

[0042] Preferably, the rinsing time is 5 to 10 seconds, for example, 5 seconds, 6 seconds, 7 seconds, 8 seconds, 9 seconds or 10 seconds.

[0043] As a preferred technical solution of the present invention, the drying includes oven drying.

[0044] Preferably, the drying temperature is 50-100°C, for example, 50°C, 60°C, 70°C, 80°C, 90°C or 100°C.

[0045] Preferably, the drying time is 10 to 60 seconds, for example, 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds or 60 seconds.

[0046] As a preferred technical solution of the present invention, after the drying, the high-purity electrolytic copper is vacuum-packed and stored.

[0047] As a preferred technical solution of the present invention, the cleaning method comprises the following steps:

[0048] The high-purity electrolytic copper plate to be cleaned is sandblasted with sand material with a particle size of 20 to 40 meshes at 0.4 to 0.7 MPa and an angle of 60 to 80 degrees, then ultrasonically washed in pure water for 3 to 5 minutes, then first acid washed for 180 to 200 seconds with a mixed acid solution, first washed in pure water for 30 to 60 seconds, then second acid washed for 60 to 80 seconds with a nitric acid solution, second washed in pure water for 10 to 30 seconds, then immersed in a dilute sulfuric acid solution for 4 to 6 hours, third acid washed, third washed in pure water for 30 to 60 seconds, then rinsed in anhydrous ethanol for 5 to 10 seconds, dried at 50 to 100° C. for 10 to 60 seconds, to obtain high-purity electrolytic copper, and stored in vacuum packaging;

[0049] Wherein, the mixed acid solution comprises electronic grade sulfuric acid with a concentration of 96-98wt%, electronic grade hydrochloric acid with a concentration of 30-40wt%, electronic grade nitric acid with a concentration of 60-70wt% and pure water; in the mixed acid solution, the mass ratio of electronic grade sulfuric acid, electronic grade hydrochloric acid, electronic grade nitric acid and pure water is 1:1:1:(5-10); the nitric acid solution comprises nitric acid with a concentration of 60-70wt% and pure water; the mass ratio of nitric acid to pure water is 1:(0.5-5); the concentration of the dilute sulfuric acid solution is 0.0001-0.001mol / L.

[0050] Compared with the prior art, the present invention has at least the following beneficial effects:

[0051] 1) The cleaning method of high-purity electrolytic copper provided by the present invention first uses sandblasting to remove some impurities that are obviously present on the surface of the high-purity electrolytic copper plate to be cleaned, and then uses a cleaning method of alternating acid washing and water washing to remove black spots on the surface, local yellowing marks, and trace impurity residues in microcracks. This process will not introduce new impurities and can meet the use requirements of high-purity copper.

[0052] 2) The cleaning method of high-purity electrolytic copper provided by the present invention avoids mixed contamination between acid solutions, and the acid solution after cleaning can be reused.

[0053] 3) The cleaning method of the high-purity electrolytic copper provided by the present invention has a one-time cleaning pass rate of 95% or more, and still maintains the purity before cleaning, the resistivity is stable, there is no obvious increase, and the storage retention period is more than 6 months. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The present invention is a schematic flow chart of a method for cleaning high-purity electrolytic copper. DETAILED DESCRIPTION

[0055] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0056] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0057] In order to demonstrate the effectiveness of the cleaning method of the present invention, the high-purity electrolytic copper plate to be cleaned in the specific embodiment of the present invention is the same electrolytic copper plate, the purity is 6N (99.9999%), and the resistivity is 0.0175Ω·mm 2 / m.

[0058] Figure 1The schematic flow diagram of the cleaning method of high-purity electrolytic copper of the present invention is shown, and the cleaning method comprises the following steps:

[0059] The high-purity electrolytic copper plate to be cleaned is sequentially subjected to pretreatment, first pickling, first water washing, second pickling, second water washing, third pickling, third water washing, rinsing and drying to obtain high-purity electrolytic copper;

[0060] Wherein, the pre-treatment includes sandblasting and washing performed in sequence.

[0061] Example 1

[0062] This embodiment provides a method for cleaning high-purity electrolytic copper, the cleaning method comprising the following steps:

[0063] The high-purity electrolytic copper plate to be cleaned is sandblasted with quartz sand with a particle size of 30 mesh at an angle of 70 degrees at 0.6Mpa, then ultrasonically washed in pure water for 5 minutes, and then a mixed acid solution prepared by 96wt% electronic-grade sulfuric acid, 35wt% electronic-grade hydrochloric acid, 65wt% electronic-grade nitric acid and pure water (mass ratio 1:1:1:7) is used for the first pickling for 185s, and a first water washing for 45s in pure water is performed, and then a nitric acid solution prepared by 65wt% nitric acid and pure water (mass ratio 1:1) is used for the second pickling for 70s, and a second water washing for 20s in pure water is performed, and then immersed in a dilute sulfuric acid solution with a concentration of 0.0005mol / L for 5h, a third pickling is performed, and a third water washing for 45s in pure water is performed, and then rinsed in anhydrous ethanol for 10s, and dried at 80°C for 30s to obtain high-purity electrolytic copper, and the high-purity electrolytic copper is put into a vacuum packaging film and vacuum-sealed for preservation.

[0064] The cleaned high-purity electrolytic copper provided in this embodiment has no yellowing or blackening on its surface after being unpacked for 6 months.

[0065] Example 2

[0066] This embodiment provides a method for cleaning high-purity electrolytic copper, the cleaning method comprising the following steps:

[0067] The high-purity electrolytic copper plate to be cleaned is sandblasted with quartz sand with a particle size of 25 mesh at an angle of 60 degrees at 0.5Mpa, then ultrasonically washed in pure water for 4 minutes, and then a mixed acid solution prepared by 97wt% electronic-grade sulfuric acid, 32wt% electronic-grade hydrochloric acid, 68wt% electronic-grade nitric acid and pure water (mass ratio 1:1:1:5) is used for the first pickling for 180s, and a first water washing for 35s in pure water is performed, and then a nitric acid solution prepared by 68wt% nitric acid and pure water (mass ratio 1:0.5) is used for the second pickling for 65s, and a second water washing for 30s in pure water is performed, and then immersed in a dilute sulfuric acid solution with a concentration of 0.0001mol / L for 6h, a third pickling is performed, and a third water washing for 35s in pure water is performed, and then rinsed in anhydrous ethanol for 8s, and dried at 60°C for 40s to obtain high-purity electrolytic copper, and the high-purity electrolytic copper is put into a vacuum packaging film and vacuum-sealed for preservation.

[0068] The cleaned high-purity electrolytic copper provided in this embodiment has no yellowing or blackening on its surface after being unpacked for 6 months.

[0069] Example 3

[0070] This embodiment provides a method for cleaning high-purity electrolytic copper, the cleaning method comprising the following steps:

[0071] The high-purity electrolytic copper plate to be cleaned is sandblasted with quartz sand with a particle size of 35 meshes at an angle of 75 degrees at 0.4Mpa, then ultrasonically washed in pure water for 3min, and then a mixed acid solution prepared by 98wt% electronic-grade sulfuric acid, 38wt% electronic-grade hydrochloric acid, 62wt% electronic-grade nitric acid and pure water (mass ratio 1:1:1:9) is used for the first pickling for 200s, and a first water washing for 60s in pure water is performed, and then a nitric acid solution prepared by 62wt% nitric acid and pure water (mass ratio 1:2) is used for the second pickling for 75s, and a second water washing for 25s in pure water is performed, and then immersed in a dilute sulfuric acid solution with a concentration of 0.001mol / L for 4h, a third pickling is performed, and a third water washing for 60s in pure water is performed, and then rinsed in anhydrous ethanol for 5s, and dried at 50°C for 60s to obtain high-purity electrolytic copper, and the high-purity electrolytic copper is put into a vacuum packaging film and vacuum-sealed for preservation.

[0072] The cleaned high-purity electrolytic copper provided in this embodiment has no yellowing or blackening on its surface after being unpacked for 6 months.

[0073] Example 4

[0074] This embodiment provides a method for cleaning high-purity electrolytic copper, the cleaning method comprising the following steps:

[0075] The high-purity electrolytic copper plate to be cleaned is sandblasted with quartz sand with a particle size of 20 mesh at an angle of 80 degrees under 0.7Mpa, then ultrasonically washed in pure water for 4min, and then a mixed acid solution prepared by 97wt% electronic-grade sulfuric acid, 40wt% electronic-grade hydrochloric acid, 60wt% electronic-grade nitric acid and pure water (mass ratio 1:1:1:8) is used for the first pickling for 190s, and a first water washing for 30s in pure water is performed, and then a nitric acid solution prepared by 60wt% nitric acid and pure water (mass ratio 1:1) is used for the second pickling for 80s, and a second water washing for 10s in pure water is performed, and then immersed in a dilute sulfuric acid solution with a concentration of 0.0003mol / L for 5h, a third pickling is performed, and a third water washing for 30s in pure water is performed, and then rinsed in anhydrous ethanol for 7s, and dried at 100°C for 10s to obtain high-purity electrolytic copper, and the high-purity electrolytic copper is put into a vacuum packaging film and vacuum-sealed for preservation.

[0076] The cleaned high-purity electrolytic copper provided in this embodiment has no yellowing or blackening on its surface after being unpacked for 6 months.

[0077] Example 5

[0078] This embodiment provides a method for cleaning high-purity electrolytic copper. The cleaning method differs from that in Embodiment 1 in that a nitric acid solution is used in the first pickling and a mixed acid solution is used in the second pickling. The remaining preparation methods and parameters are consistent with those in Embodiment 1.

[0079] After the cleaned high-purity electrolytic copper provided in this embodiment is unpacked after being stored for 6 months, a large area of ​​the surface becomes obviously yellow and black.

[0080] Example 6

[0081] This embodiment provides a method for cleaning high-purity electrolytic copper. The cleaning method differs from that of Embodiment 1 in that a dilute sulfuric acid solution is used in the first pickling and a mixed acid solution is used in the third pickling. The remaining preparation methods and parameters are consistent with those of Embodiment 1.

[0082] After the cleaned high-purity electrolytic copper provided in this embodiment is unpacked after being stored for 6 months, a large area of ​​the surface becomes obviously yellow and black.

[0083] Example 7

[0084] This embodiment provides a method for cleaning high-purity electrolytic copper. The cleaning method differs from that in Example 1 in that, in the second pickling, the nitric acid solution is replaced by a hydrochloric acid solution prepared by hydrochloric acid having a concentration of 65wt% and pure water (mass ratio 1:1), and the remaining preparation methods and parameters are consistent with those in Example 1.

[0085] After the cleaned high-purity electrolytic copper provided in this embodiment is unpacked after being stored for 6 months, a large area of ​​the surface becomes obviously yellow and black.

[0086] Example 8

[0087] This embodiment provides a method for cleaning high-purity electrolytic copper. The cleaning method differs from that in Embodiment 1 in that the dilute sulfuric acid solution is replaced by a dilute hydrochloric acid solution of equal concentration in the third acid wash, and the remaining preparation methods and parameters remain the same as those in Embodiment 1.

[0088] After the cleaned high-purity electrolytic copper provided in this embodiment is unpacked after being stored for 6 months, a large area of ​​the surface becomes obviously yellow and black.

[0089] Example 9

[0090] This embodiment provides a method for cleaning high-purity electrolytic copper. The cleaning method is different from that in Embodiment 1 in that the first pickling time is 160 seconds, and the other preparation methods and parameters are consistent with those in Embodiment 1.

[0091] After cleaning, the high-purity electrolytic copper provided in this embodiment still has impurities on its surface, and is not cleaned thoroughly.

[0092] Example 10

[0093] This embodiment provides a method for cleaning high-purity electrolytic copper. The cleaning method is different from that in Embodiment 1 in that the second pickling time is 50 seconds, and the other preparation methods and parameters are consistent with those in Embodiment 1.

[0094] After cleaning, the high-purity electrolytic copper provided in this embodiment still has impurities on its surface, and is not cleaned thoroughly.

[0095] Embodiment 11

[0096] This embodiment provides a method for cleaning high-purity electrolytic copper. The cleaning method is different from that in Embodiment 1 in that the immersion time of the third pickling is 3 hours, and the other preparation methods and parameters are consistent with those in Embodiment 1.

[0097] The surface of the cleaned high-purity electrolytic copper provided in this embodiment is yellow.

[0098] Example 12

[0099] This embodiment provides a method for cleaning high-purity electrolytic copper. The cleaning method is different from that in Embodiment 1 in that the immersion time of the third pickling is 7 hours, and the other preparation methods and parameters are consistent with those in Embodiment 1.

[0100] Black spots appear on the surface of some of the high-purity electrolytic copper after cleaning provided in this embodiment.

[0101] Example 13

[0102] This embodiment provides a method for cleaning high-purity electrolytic copper. The cleaning method is different from that in Embodiment 1 in that the time for the third water washing is 20 seconds, and the other preparation methods and parameters are consistent with those in Embodiment 1.

[0103] The cleaned high-purity electrolytic copper provided in this embodiment has black spots on its surface after drying.

[0104] Embodiment 14

[0105] This embodiment provides a method for cleaning high-purity electrolytic copper. The cleaning method is different from that in Embodiment 1 in that the time for the third water washing is 70 seconds, and the other preparation methods and parameters are consistent with those in Embodiment 1.

[0106] The surface of the cleaned high-purity electrolytic copper provided in this embodiment turns yellow and oxidized after drying.

[0107] Comparative Example 1

[0108] This comparative example provides a method for cleaning high-purity electrolytic copper. The cleaning method is different from Example 1 in that the pretreatment process is omitted, and the remaining preparation methods and parameters are consistent with Example 1.

[0109] The surface of the high-purity electrolytic copper after cleaning provided in this comparative example still has impurities and is not cleaned thoroughly.

[0110] Comparative Example 2

[0111] This comparative example provides a method for cleaning high-purity electrolytic copper. The cleaning method differs from Example 1 in that the first acid wash and the first water wash are omitted, and the remaining preparation methods and parameters are consistent with those of Example 1.

[0112] The surface of the high-purity electrolytic copper after cleaning provided in this comparative example still has impurities such as oxides, and is not cleaned thoroughly.

[0113] Comparative Example 3

[0114] This comparative example provides a method for cleaning high-purity electrolytic copper. The cleaning method differs from that in Example 1 in that the second acid wash and the second water wash are omitted, and the remaining preparation methods and parameters are consistent with those in Example 1.

[0115] The high-purity electrolytic copper provided in this comparative example still has impurities on its surface after cleaning, and is not cleaned thoroughly.

[0116] Comparative Example 4

[0117] This comparative example provides a method for cleaning high-purity electrolytic copper. The cleaning method differs from that in Example 1 in that the third acid wash and the third water wash are omitted, and the remaining preparation methods and parameters are consistent with those in Example 1.

[0118] The surface of the cleaned high-purity electrolytic copper provided in this comparative example turns yellow, oxidized and black after being dried.

[0119] Comparative Example 5

[0120] This comparative example provides a method for cleaning high-purity electrolytic copper. The cleaning method differs from Example 1 in that a first acid wash, a second acid wash and a third acid wash are performed in sequence, and then a first water wash, a second water wash and a third water wash are performed in sequence. The remaining preparation methods and parameters are consistent with Example 1.

[0121] The surface of the cleaned high-purity electrolytic copper provided in this comparative example turns yellow and oxidizes.

[0122] The cleaned high-purity electrolytic copper provided in Examples 1 to 14 and Comparative Examples 1 to 5 was tested for resistivity and purity. The specific test results are shown in Table 1.

[0123] Table 1

[0124]

[0125]

[0126] The test results show that:

[0127] (1) It can be seen from Examples 1 to 4 that the present invention sequentially performs pre-treatment, first pickling, first water washing, second pickling, second water washing, third pickling, third water washing, rinsing and drying on the high-purity electrolytic copper plate, and the obtained high-purity electrolytic copper has a one-time cleaning pass rate of 95% or more, and still maintains the purity before cleaning, and the resistivity remains stable without obvious increase, and the storage retention period is more than 6 months. After unpacking, the surface does not turn yellow or black.

[0128] (2) It can be seen from Examples 1 and 5-8 that the present invention matches the acid solutions used in the first pickling, the second pickling and the third pickling, respectively, so that the high-purity electrolytic copper plate can be cleaned layer by layer, thereby ensuring that the impurities and dirt on the surface of the high-purity electrolytic copper are cleaned, the qualified rate of one cleaning is high, and the surface color is consistent, and it can be preserved for a long time.

[0129] (3) It can be seen from Example 1 and Examples 9-14 that the first pickling time of the present invention is 180-200s, the second pickling time is 60-80s, the third pickling immersion time is 4-6h, and the third water washing time is 30-60s, which can ensure that the cleaning at each stage is thorough and will not further cause the purity of the high-purity electrolytic copper to decrease and the resistivity to increase. The storage retention period is more than 6 months. After unpacking, the surface does not turn yellow or black.

[0130] (4) It can be seen from Example 1 and Comparative Examples 1-5 that the present invention first uses sandblasting to remove some impurities that are obviously present on the surface of the high-purity electrolytic copper plate to be cleaned, and then adopts a cleaning method of alternating pickling and water washing to remove black spots on the surface, traces of local yellowing, and trace impurity residues in microcracks, and will not introduce new impurities. If any of the cleaning processes is omitted, the cleaning effect of Example 1 cannot be achieved, and the qualified rate and purity of one-time cleaning will be reduced, and the resistivity will be significantly increased. If pickling is performed first and then water washing is performed in sequence, different acids will interfere with each other during the pickling process, resulting in the product being unable to be cleaned, and black spots and obvious pickling marks will be generated.

[0131] In summary, in the present invention, sandblasting is first used to remove some impurities that are obviously present on the surface of the high-purity electrolytic copper plate to be cleaned, and then a cleaning method of alternating acid washing and water washing is used to remove residual black spots, yellowing marks and trace impurities in microcracks layer by layer. This process will not introduce new impurities and can meet the use requirements of high-purity electrolytic copper; at the same time, the acid solution after cleaning can be reused without causing pollution between acid solutions; the qualified rate of one cleaning can reach 95% or more, and the purity before cleaning is still maintained, the resistivity is stable, there is no obvious increase, and the storage retention period is more than 6 months.

[0132] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for cleaning high-purity electrolytic copper, characterized in that: The cleaning method comprises the following steps: The high-purity electrolytic copper plate to be cleaned is sequentially subjected to pretreatment, first pickling, first water washing, second pickling, second water washing, third pickling, third water washing, rinsing and drying to obtain high-purity electrolytic copper; Wherein, the pre-treatment includes sandblasting and washing performed in sequence.

2. The cleaning method according to claim 1, characterized in that: The pressure of the sandblasting treatment is 0.4-0.7 MPa; Preferably, the angle of the sandblasting is 60 to 80 degrees; Preferably, the sand material for sandblasting comprises white corundum or quartz sand; Preferably, the particle size of the sand material is 20 to 40 meshes; Preferably, the washing is performed by pure water ultrasonic washing; Preferably, the washing time is 3 to 5 minutes.

3. The cleaning method according to claim 1 or 2, characterized in that: The acid used in the first pickling comprises a mixed acid solution; Preferably, the mixed acid solution comprises electronic grade sulfuric acid, electronic grade hydrochloric acid, electronic grade nitric acid and pure water; Preferably, the concentration of the electronic grade sulfuric acid is 96-98 wt %; Preferably, the concentration of the electronic grade hydrochloric acid is 30-40wt%; Preferably, the concentration of the electronic grade nitric acid is 60-70wt%; Preferably, in the mixed acid solution, the mass ratio of electronic grade sulfuric acid, electronic grade hydrochloric acid, electronic grade nitric acid and pure water is 1:1:1:(5-10); Preferably, the first pickling time is 180 to 200 seconds.

4. The cleaning method according to any one of claims 1 to 3, characterized in that: The acid used in the second pickling comprises a nitric acid solution; Preferably, the nitric acid solution comprises nitric acid and pure water; Preferably, the concentration of the nitric acid is 60-70wt%; Preferably, the mass ratio of the nitric acid to pure water is 1:(0.5-5); Preferably, the second pickling time is 60 to 80 seconds.

5. The cleaning method according to any one of claims 1 to 4, characterized in that: The third pickling is soaking in a dilute sulfuric acid solution; Preferably, the concentration of the dilute sulfuric acid solution is 0.0001 to 0.001 mol / L; Preferably, the immersion time of the third pickling is 4 to 6 hours.

6. The cleaning method according to any one of claims 1 to 5, characterized in that: The water used in the first water washing, the second water washing and the third water washing each independently comprises pure water; Preferably, the first washing time is 30 to 60 seconds; Preferably, the second water washing time is 10 to 30 seconds; Preferably, the third water washing time is 30 to 60 seconds.

7. The cleaning method according to any one of claims 1 to 6, characterized in that: The rinsing is carried out in anhydrous ethanol; Preferably, the rinsing time is 5 to 10 seconds.

8. The cleaning method according to any one of claims 1 to 7, characterized in that: The drying includes drying; Preferably, the drying temperature is 50-100°C; Preferably, the drying time is 10 to 60 seconds.

9. The cleaning method according to any one of claims 1 to 8, characterized in that: After the drying, the high-purity electrolytic copper is vacuum packaged and stored.

10. The cleaning method according to claim 1, characterized in that: The cleaning method comprises the following steps: The high-purity electrolytic copper plate to be cleaned is sandblasted with sand material with a particle size of 20 to 40 meshes at 0.4 to 0.7 MPa and an angle of 60 to 80 degrees, then ultrasonically washed in pure water for 3 to 5 minutes, then first acid washed for 180 to 200 seconds with a mixed acid solution, first washed in pure water for 30 to 60 seconds, then second acid washed for 60 to 80 seconds with a nitric acid solution, second washed in pure water for 10 to 30 seconds, then immersed in a dilute sulfuric acid solution for 4 to 6 hours, third acid washed, third washed in pure water for 30 to 60 seconds, then rinsed in anhydrous ethanol for 5 to 10 seconds, dried at 50 to 100° C. for 10 to 60 seconds, to obtain high-purity electrolytic copper, and stored in vacuum packaging; Wherein, the mixed acid solution comprises electronic grade sulfuric acid with a concentration of 96-98wt%, electronic grade hydrochloric acid with a concentration of 30-40wt%, electronic grade nitric acid with a concentration of 60-70wt% and pure water; in the mixed acid solution, the mass ratio of electronic grade sulfuric acid, electronic grade hydrochloric acid, electronic grade nitric acid and pure water is 1:1:1:(5-10); the nitric acid solution comprises nitric acid with a concentration of 60-70wt% and pure water; the mass ratio of nitric acid to pure water is 1:(0.5-5); the concentration of the dilute sulfuric acid solution is 0.0001-0.001mol / L.

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