A flattening solution based on double pulse electrolysis power supply and a method for removing scratch defects on the surface of copper wire

Abstract

The application discloses a flattening solution based on a double-pulse electrolysis power supply and a flattening method for scratch defects on the surface of copper wire, and the flattening solution comprises copper salt, a complexing agent, a first flattening agent, a second flattening agent, a stabilizing agent and an electrolytic salt, and the solution is alkaline, wherein the first flattening agent is quaternary ammonium base or quaternary ammonium salt, and the second flattening agent is hydroxylamine sulfonate. The double-pulse electrolysis flattening solution provided by the application realizes selective electroplating pretreatment on the micron-level scratch defect area on the surface of the copper wire through the synergistic complementary function of the first flattening agent and the second flattening agent in the process of cyclic switching of the positive and negative output ends of the double-pulse electrolysis power supply, and realizes the construction method of the double-pulse electrolysis flattening solution of the effective process technology for filling the recessed and peeled protrusions and the application target.

Description

Technical Field

[0001] This invention discloses a method for leveling solutions and surface scratches on copper wires based on a dual-pulse electrolysis power supply, belonging to the field of surface treatment technology for precision semiconductor electronic products. Background Technology

[0002] In industries such as wire and cable, electronic components, new energy vehicle battery busbars, and precision connectors, high-purity, high-performance copper wire is an indispensable key material. Its surface quality directly determines the conductivity, mechanical strength, corrosion resistance, and reliability of subsequent processing. However, during the drawing, annealing, transportation, and subsequent braiding processes, various microscopic or macroscopic scratches inevitably occur on the surface of copper wire. These scratches affect the smoothness of the electronic product surface and severely impact its performance and further processing. Therefore, effectively leveling and repairing copper wire with scratches to improve its surface quality is a long-standing and urgent technical challenge in the industry.

[0003] Currently, the main methods for leveling and repairing scratches on the surface of copper wires include mechanical polishing, chemical polishing, and electroplating. Mechanical polishing, a physical method, primarily uses polishing wheels and belts to grind the surface of the copper wire. This method has limited effectiveness in leveling microscopic defects and deep, narrow scratches, and is prone to generating new scratches and thermal stress. Chemical polishing, on the other hand, suffers from poor uniformity in leveling, easily leading to over- or under-corrosion, altering the surface chemical composition and crystal structure of the copper wire, and potentially introducing new impurities or reducing surface conductivity. Electroplating, which covers defects by electroplating a new copper layer onto the surface of the copper wire, is a relatively common method. However, its inherent limitations restrict its repair effectiveness: First, traditional DC electroplating has poor dispersion capabilities. Deposition is fast at high current density points and edges, but slow or even impossible in low current density areas such as scratches and pits, resulting in a "dog-bone" phenomenon (the defect cannot be effectively filled, and the surface becomes even more uneven). Secondly, to cover deep scratches, a thicker plating layer is often required. This is not only costly and inefficient, but an excessively thick plating layer can also alter the mechanical properties of the copper wire (such as making it brittle) and may mask other defects in the substrate material. Pulse electroplating improves the density and dispersion of the plating layer by periodically switching the current on and off, which is an improvement over DC electroplating. However, it still falls short in dealing with deep and narrow microscopic scratches. Its main problems are: the adjustment freedom of single-pulse parameters is limited, its adaptability to complex defects is not strong, and its leveling ability is difficult to improve further after reaching a certain level. For precision copper wires with extremely high requirements, the leveling effect is still not ideal. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide a leveling solution based on a dual-pulse electrolytic power supply and a method for leveling scratch defects on the surface of copper wires. By adjusting the formulation of the leveling solution and the proportion of each component, and combining it with a dual-pulse electrolytic plating method, the leveling of scratch defects is achieved, thereby solving the technical problem that existing technologies cannot effectively level scratch defects.

[0005] To address the aforementioned problems, this invention first provides a leveling solution based on a dual-pulse electrolytic power supply, comprising the following components: copper salt with a concentration of 9-21 g / L (calculated as copper), complexing agent 24-36 g / L, first leveling agent 4-10 g / L, second leveling agent 9-15 g / L, stabilizer 4.5-13.5 g / L, electrolytic salt 10-20 g / L, solution temperature 40-60℃, and solution pH 12.0-14.0. The first leveling agent is a quaternary ammonium base or quaternary ammonium salt, and the second leveling agent is a hydroxylamine sulfonate.

[0006] The components used in this invention are of superior purity, which is beneficial for improving the purity of the dual-pulse electrolytic leveling solution and its performance in leveling scratch defects.

[0007] In one embodiment of the present invention, the copper salt is one or more of copper cyanide, copper phosphate, copper nitrate hydrate, cuprous cyanide, copper chloride dihydrate, water, and copper pyrophosphate, preferably cuprous cyanide.

[0008] In one embodiment of the present invention, the complexing agent is one or more of sodium cyanide, potassium cyanide, tetraethylammonium cyanide, and tetrabutylammonium cyanide, preferably sodium cyanide and potassium cyanide.

[0009] In one embodiment of the present invention, the first leveling agent is one or more of tetramethylammonium tetrafluoroborate, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, tetraoctylammonium hydroxide, trimethylphenylammonium hydroxide, and hexadecyltrimethylammonium hydroxide.

[0010] In one embodiment of the present invention, the second leveling agent is one or more of the following: sodium trihydroxymethylaminopropanesulfonate, 3-(N,N-dimethylhexadecylammonium)propanesulfonate, sodium 3-(N-ethyl-3-methylaniline)-2-hydroxypropanesulfonate, N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate, 3-[N-tri(hydroxymethyl)methylamine]-2-hydroxypropanesulfonic acid, sodium trihydroxymethylaminopropanesulfonate, N-tetradecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate, and N-[tri(hydroxymethyl)methyl]-3-aminopropanesulfonic acid.

[0011] In one embodiment of the present invention, the stabilizer is an alcoholamine containing one to five hydroxyl groups or a salt thereof, specifically one or more of ethanolamine, diethanolamine, triethanolamine, triisopropanolamine, N-butyldiethanolamine, 2-hydroxymethyl-1,3-propanediol, 2-benzylamino-2-hydroxymethyl-1,3-propanediol hydrochloride, 2-(2-hydroxyethylamino)-2-hydroxymethyl-1,3-propanediol, 2-di(2-hydroxyethyl)amino-2-hydroxymethyl-1,3-propanediol, triethanolamine borate, and N-phenyldiethanolamine, preferably an alcoholamine containing three or more hydroxyl groups, preferably one or more of triethanolamine, triisopropanolamine, 2-(2-hydroxyethylamino)-2-hydroxymethyl-1,3-propanediol, 2-di(2-hydroxyethyl)amino-2-hydroxymethyl-1,3-propanediol, triethanolamine borate, and 2-benzylamino-2-hydroxymethyl-1,3-propanediol hydrochloride.

[0012] In one embodiment of the present invention, the electrolytic salt is sodium hydroxide or potassium hydroxide.

[0013] In one embodiment of the present invention, the pH adjuster for adjusting the pH value of the solution includes pH-increasing compounds and pH-decreasing compounds; the pH-increasing compounds are sodium hydroxide and potassium hydroxide; the pH-decreasing compounds are one or more of methanesulfonic acid, ethylsulfonic acid, and 4-dodecylbenzenesulfonic acid.

[0014] This invention also provides a method for smoothing scratch defects on the surface of copper wire, comprising the following steps:

[0015] S1. The copper wire is subjected to ultrasonic degreasing, pure water cleaning, cathode electrolytic degreasing, pure water cleaning, anodic electrolytic degreasing, pure water cleaning, electrolytic acid activation, and pure water cleaning in sequence.

[0016] S2. Prepare a leveling solution, place the continuously running copper wire in the leveling solution as the cathode, and connect it to the cathode output of the bidirectional pulse electrolysis power supply; the electrolytic copper plate below the copper wire is used as the anode and connected to the anode output of the bidirectional pulse electrolysis power supply; and electrolytically level the scratches and defects on the surface of the copper wire to obtain the copper wire pretreatment product.

[0017] S3. Place the copper wire pretreatment product obtained in step S2 into a silver plating device for silver plating to obtain silver-plated copper wire.

[0018] In one embodiment of the present invention, in step S2, during electrolytic leveling, the temperature of the leveling solution is 40~60°C.

[0019] In one embodiment of the present invention, in step S2, when electrolytically leveling the scratches on the surface of the copper wire using a bidirectional pulse electrolysis power supply, the forward pulse current is set to I1 and the forward pulse electrolysis time to t1, and the reverse pulse current is set to I2 and the reverse pulse electrolysis time to t2. When the bidirectional pulse electrolysis power supply starts operating, the copper wire acts as the cathode in the electrolytic treatment process of the leveling solution. After the forward pulse output current I1 and the forward pulse electrolysis time t1 have ended, the anode output terminal of the bidirectional pulse electrolysis power supply switches to the cathode output terminal, and the cathode output terminal switches to the anode output terminal. That is, the copper wire is switched to the anode, and the electrolytic copper plate below the copper wire is switched to the cathode. The electrolysis treatment is carried out in an orderly cyclic manner according to the set reverse pulse current I2 and the reverse pulse electrolysis time t2 until the set electrolysis treatment time ends. After washing and drying, the pre-treated copper wire product with surface scratches leveled by electrolysis is obtained.

[0020] In one embodiment of the present invention, step S2, the preparation of the leveling solution, is as follows: First, 100 liters of pure water are added to the electrolytic cell. Under stirring conditions, the electrolytic salt, complexing agent, first leveling agent aqueous solution, copper salt, stabilizer, and second leveling agent are added sequentially in small amounts. After all the components are dissolved and uniformly mixed, pure water is added to a total solution volume of 200 liters. The pH value of the solution is tested and controlled between 12 and 14. Finally, pure water is added to a total solution volume of 210 liters to obtain the dual-pulse electrolytic leveling solution. When the solution pH is too high, ethylsulfonic acid solution is used to lower the pH value; when it is too low, potassium hydroxide solution is used to raise the pH value.

[0021] In one embodiment of the present invention, in step S2, the ratio of the forward pulse current I1 to the reverse pulse current I2 is in the range of 1:3 to 1:9, and the ratio of the forward pulse electrolysis time t1 to the reverse pulse electrolysis time t2 is in the range of 5 to 11:1.

[0022] In one embodiment of the present invention, in step S2, the positive pulse current I1 ranges from 2.7 to 1.6 amperes, and the reverse pulse current I2 ranges from 8.1 to 14.4 amperes.

[0023] In one embodiment of the present invention, in step S2, the forward pulse electrolysis time is 30~55ms, the reverse pulse electrolysis time is 5~6ms, and the total electrolysis time is 35~61s.

[0024] In one embodiment of the present invention, in step S3, the electroplating solution used for silver plating includes potassium silver cyanide as the main salt with a concentration of 60 g / L (calculated as silver), sodium cyanide 170 g / L, Ag-903 plating starter 35 ml / L, and pH 8.5.

[0025] In one embodiment of the present invention, in step S3, the current density during silver plating is 85 A / dm. 2 The electroplating solution temperature was 45℃, and the electroplating time was 38 seconds; the target silver film thickness was set at 3.5μm.

[0026] The principle of this invention for leveling copper wires with surface scratches is as follows:

[0027] First, during forward pulse electrolysis using a dual-pulse electrolysis power supply, the surface of the copper wire serving as the cathode, based on the principle of mutual attraction between positive and negative charges, attracts monovalent copper ions (Cu). + Ammonium ions from the first leveling agent accumulate on its surface. During operation under the set conditions of positive pulse current I1 and positive pulse electrolysis time t1, monovalent copper ions Cu... + After gaining electrons and being reduced to copper atoms, the copper ions are deposited on the surface of the copper wire to form a copper plating layer. During the reduction of copper ions, ammonium ions act as competitors and hinder the reduction of copper ions. That is, compared with the flat areas on the surface of the copper wire, the surface with scratches is more likely to attract copper ions with smaller space due to the complex morphology of the surface with scratches. This allows the copper ions to be reduced first and form a copper plating layer, so that the surface with scratches is leveled and gradually approaches the flat areas of the copper wire surface.

[0028] Secondly, hydroxymethylamine sulfonate, as the second leveling agent, has an intramolecular structure of ammonium cation and sulfonate anion. The ammonium cation will also migrate to the surface of the copper wire that presents the cathode and participate in the copper ion reduction process, competing with the copper ion reduction process. Since the ammonium cation in the second leveling agent has a larger spatial volume than the ammonium ion in the first leveling agent, after being adsorbed at the scratches on the surface of the copper wire, it will leave a larger spatial structure, making it easier to level the scratches and troughs on the surface of the copper wire. However, since the second leveling agent also has the structure of acid anion, it forms a negative-negative repulsion with the surface of the copper wire at the cathode. Therefore, its leveling function can only play a synergistic role in the second position compared with the first leveling agent, tetrabutylammonium hydroxide.

[0029] The stabilizer, based on its three hydrophilic hydroxyl groups, easily adheres to the surface of the electrolytic copper plate presenting the anode, thus preventing and controlling the electrolytic stripping of the anode copper plate. At the same time, the sulfonate anions in the second leveling agent have a positive-negative attraction with the surface of the electrolytic copper plate presenting the anode, which also plays a synergistic role in preventing and controlling the electrolytic stripping of the anode copper plate. This efficiently eliminates the side reaction of unnecessary electrolytic stripping of the anode copper plate.

[0030] The cathode output of the bidirectional pulse electrolysis power supply is connected to the copper wire. During the operation of the closed electrolysis circuit, after the set positive pulse current I1 and positive pulse electrolysis time t1 are completed, the anode output of the bidirectional pulse electrolysis power supply 500 switches to the cathode output, and simultaneously, its cathode output switches to the anode output. That is, when the copper wire is switched to the anode, the surface of the copper wire, which serves as the anode, also has an intramolecular structure of ammonium cations and sulfonate anions, based on the principle of positive and negative attraction. The sulfonate anion RSO3 - The adsorption is uniform and orderly on the surface of the copper wire, which exhibits anodic function. However, in areas with scratches or defects, the uneven surface makes it difficult to form a uniform and orderly adsorption state. Therefore, during the operation of the bidirectional pulse electrolysis power supply under the set reverse pulse current I2 and reverse pulse electrolysis time t2, the copper on the surface of the copper wire is electrolytically stripped. During the electrolytic stripping process, the second leveling agent hinders the electrolytic stripping of copper from the surface of the copper wire. That is, compared with the flat areas, the scratched areas of the copper wire have a more complex surface morphology and a larger volume of sulfonate anions RSO3. - The strength of the attraction is weakened. Therefore, the low point of the scratched surface is more likely to be positively and negatively attracted to the copper ions with small space volume. The copper on the surface of the copper wire is electrolytically stripped first, so that the low point of the scratched surface of the copper wire is leveled and gradually approaches the flat area of ​​the copper wire surface.

[0031] Secondly, the stabilizer, based on its three hydrophilic hydroxyl groups, easily adheres to the surface of the copper wire that presents the anode, thus preventing the electrolytic stripping of the anode copper wire in the flat area. Similarly, the adsorption state in the flat areas of the copper wire surface is uniform and orderly, while the scratched areas, due to their uneven surface, are difficult to form a uniform and orderly adsorption state. Therefore, the low points of the scratched surface are more likely to attract copper ions with small spatial volume, thus preferentially completing the electrolytic stripping of copper from the surface of the copper wire. This makes the low points of the scratched surface of the copper wire leveled and gradually approach the flat areas of the copper wire surface.

[0032] Beneficial effects:

[0033] 1. This invention selects quaternary ammonium base or quaternary ammonium salt as the first leveling agent and hydroxymethylamine sulfonate, which has a larger spatial volume, as the second leveling agent. A leveling solution is prepared by combining copper salt, complexing agent, stabilizer, and electrolytic salt. This solution is then used in conjunction with a dual-pulse electrolytic plating process to electrolytically level copper wires with surface scratches. The dual-pulse electrolytic leveling solution provided by this invention, through the synergistic and complementary functions of the first and second leveling agents during the cyclic switching of the positive and negative output terminals of the dual-pulse electrolytic power supply, selectively pre-treats micron-level scratch defect areas on the surface of the copper wire for electroplating pretreatment. This comprehensive technology of electrolytic leveling solution preferentially electrolytically removes copper from concave areas and electrolytically strips copper from convex areas, achieving an effective process technology for filling concave areas and stripping convex areas. This invention provides a method for constructing a dual-pulse electrolytic power supply leveling solution and its application objectives.

[0034] 2. The present invention selects alkanolamines with three or more hydroxyl groups as stabilizers, which can effectively prevent the anode from being electrolytically stripped. The stabilizers, together with the first leveling agent and the second leveling agent, can effectively improve the surface scratch defects of the copper wire. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the existing electroplating pretreatment process.

[0036] Figure 2 This is a schematic diagram of the dual-pulse electrolytic leveling pretreatment process for electroplating according to the present invention.

[0037] Figure 3 This is a schematic diagram of the dual-pulse electrolytic leveling device of the present invention, wherein 600 is the electrolytic leveling device; 200 is the electrolytic leveling solution mother tank; 210 is the upper electrolytic leveling solution reaction tank; 220 is the lower electrolytic leveling solution reaction tank; 300a is the inlet winding copper wire conductive wheel of the electrolytic leveling device; 300b is the outlet winding copper wire conductive wheel of the electrolytic leveling device; and 500 is the dual-pulse electrolytic power supply.

[0038] Figure 4 This is a schematic diagram of the copper wire winding power supply wheel of the dual-pulse electrolytic leveling device of the present invention, wherein 300a is the inlet winding copper wire conductive wheel of the electrolytic leveling device; and 300b is the outlet winding copper wire conductive wheel of the electrolytic leveling device.

[0039] Figure 5 This is a schematic diagram of the copper wire winding power supply wheel of the silver plating device of the present invention, wherein 700 is the silver plating device; 710a is the copper wire winding conductive wheel at the inlet of the silver plating device; and 710b is the copper wire winding conductive wheel at the outlet of the silver plating device.

[0040] Figure 6 This is a schematic diagram of the silver-plated copper wire winding sample of the present invention.

[0041] Figure 7This is a schematic diagram of the inspection of a silver-plated copper wire winding sample using an HK830 optical microscope according to the present invention.

[0042] Figure 8 This is a schematic diagram of the detection of a single metal needle and a wound sample in Embodiment 4 of the present invention.

[0043] Figure 9 This is a schematic diagram of the detection of a single metal needle and a wound sample in Comparative Example 1 of the present invention. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0045] Test method:

[0046] 1. Testing the adhesion of metal coatings:

[0047] The adhesion of the metal coating was tested in accordance with the national standard GB / T 5270-2005 "Review of test methods for adhesion strength of metal coatings by electrodeposition and chemical deposition on metal substrates".

[0048] Test methods: such as Figure 6 As shown, after the silver-plated copper wire is bent and wound fourteen times, the condition of the bent surface is observed under 150x magnification. The judgment criterion is based on the proportion of the area where the plating has peeled off.

[0049] At 镀层脱落面积 / At 镀层总面积 =0 Excellent

[0050] 0 < At 镀层脱落面积 / At 镀层总面积 ≤1% Good

[0051] 1% < At 镀层脱落面积 / At 镀层总面积 <5% qualified

[0052] 5% ≤ At 镀层脱落面积 / At 镀层总面积 Unqualified

[0053] 2. Visual inspection of silver-plated copper wire;

[0054] Smooth and flat surface

[0055] Surface scratches are unacceptable.

[0056] Surface unevenness is unacceptable.

[0057] 3. Surface roughness test of silver-plated copper wire

[0058] The inspection was conducted in accordance with the national standard GB / T3505-2000 and using the VR-6000 3D profile measuring instrument manufactured by Keyence.

[0059] Surface arithmetic mean roughness Ra determination:

[0060] 110nm≤Ra<125nm Excellent

[0061] 125nm≤Ra<135nm is acceptable

[0062] 135nm≤Ra is unqualified

[0063] 4. Comprehensive evaluation of silver-plated copper wire;

[0064] Smooth and flat surface + no exposed copper + excellent performance (110nm≤Ra<125nm)

[0065] Surface scratches + (no) exposed copper + regardless of grade Ra, unqualified

[0066] Surface unevenness + (no) exposed copper + regardless of grade Ra, it is unqualified.

[0067] In summary, the comprehensive judgment can only be considered excellent if the bonding strength is excellent, the surface is smooth and flat without exposed copper, and the surface arithmetic mean roughness Ra meets the condition of 110nm≤Ra<125nm.

[0068] Any other permutation or combination is deemed unqualified based on the overall criteria.

[0069] Example 1

[0070] A leveling solution based on a dual-pulse electrolysis power supply comprises the following components: 15 g / L potassium hydroxide (electrolytic salt), 25.8 g / L potassium cyanide (complexing agent), 10.5 g / L cuprous cyanide (calculated as copper), 7.5 g / L triethanolamine (stabilizer), 5.3 g / L tetraethylammonium hydroxide (first leveling agent), 10.5 g / L N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate (second leveling agent), and a solution pH of 13. The alkali used to adjust the pH is a 20% sodium hydroxide solution, and the acid used to adjust the pH is a 5% ethylsulfonic acid solution.

[0071] A method for electrolytically leveling scratches on the surface of copper wire includes the following steps:

[0072] Step 1: For copper wires with surface scratches, perform the following steps sequentially: ultrasonic degreasing, pure water cleaning, cathode electrolytic degreasing, pure water cleaning, anodic electrolytic degreasing, pure water cleaning, electrolytic acid activation, and pure water cleaning, referring to... Figure 2The process preceding the electrolytic leveling process;

[0073] Step 2: Place the leveling solution based on the dual-pulse electrolysis power supply in... Figure 3 In the electrolytic cell 200 of the electrolytic equipment shown, the temperature is raised to 50°C. A titanium blue containing a copper plate is connected to the anode output terminal of a bidirectional pulse electrolytic power supply 500 via a conductive connecting rod. The inlet conductive wheel 300a and outlet conductive wheel 300b, with copper wire wound with surface scratches, are connected to the cathode output terminal of the bidirectional pulse electrolytic power supply 500 via a negative conductive connecting rod. The bidirectional pulse electrolytic power supply is used to electrolytically level the scratches on the copper wire surface. The forward pulse current is set to I1, the forward pulse electrolysis time to t1, and the reverse pulse current is set to I2, the reverse pulse electrolysis time to t2. When the bidirectional pulse electrolytic power supply 500 starts operating, the copper in the upper electrolytic cell 210... The copper wire material in the lower electrolytic cell 220 is wound and contacted with the inlet conductive wheel 300a and the outlet conductive wheel 300b. In the electrolytic cells 210 and 220, the copper wire acts as the cathode in the electrolytic treatment process of the leveling solution. Simultaneously, after the positive pulse output current I1 and the positive pulse electrolysis time t1 are completed, the anode output terminal of the bidirectional pulse electrolysis power supply 500 switches to the cathode output terminal, and vice versa. That is, the copper wire is switched to the anode, and the titanium blue containing the copper plate is switched to the cathode. Electrolysis is then performed in an orderly cyclic manner according to the set reverse pulse current I2 and reverse pulse electrolysis time t2 until the set electrolysis treatment time ends. After washing and drying, the pre-treated copper wire product with surface scratches and defects leveled by electrolysis is obtained.

[0074] Among them, the electrolytic equipment for leveling the copper wire to be processed is simple as follows: Figure 4 As shown, the copper wire has a diameter of 1.18 mm. During the leveling process for copper wire with surface scratches, eight turns of copper wire are wound around the inlet conductive wheel 300a and outlet conductive wheel 300b in the equipment's transport direction. This forms two layers of eight copper wires wound on each side in the leveling electrolytic solution tank; therefore, a total of 16 copper wires, each 1500 mm in diameter, are immersed in the solution. Thus, the total area D of the copper wires immersed in the leveling solution is: 16 × 1500 × (1.18 / 2). 2 ×3.14 = 26232.816 mm 2 =2.623dm 2 .

[0075] Step 3: Place the copper wire pretreatment product obtained in Step 2 in a container such as... Figure 5The silver plating process is carried out in the silver plating apparatus 700 shown. In the silver plating apparatus, the solvent in the electroplating solution is pure water, including the main salt potassium silver cyanide with a concentration of 60 g / L (based on silver), sodium cyanide 170 g / L, Ag-903 plating starter (Dongguan Cuyu New Materials Co., Ltd.) 35 mL / L, and pH 8.5. The silver plating conditions are a current of 85 A / dm². 2 Solution temperature 45℃, electroplating time 38 seconds; target silver film thickness set at 3.5μm;

[0076] Among them, copper wire pretreatment products pass Figure 5 The inlet conductive wheel 710a and outlet conductive wheel 710b shown are wound 19 times, forming two layers of 19 copper wires wound simultaneously in the silver plating solution bath; that is, a total of 38 copper wires, each 3500mm in diameter, are immersed in the silver plating solution. Therefore, the total area of ​​the copper wires immersed in the silver plating solution is... S The result is: 38 × 3500 × (1.18 / 2) 2 ×3.14 = 145373.522 mm 2 =14.537dm 2 .

[0077] In step 2 of Example 1, the forward pulse current I1 is 2.7 amperes, the forward pulse electrolysis time is t1 and 36 ms, the reverse pulse current I2 is 8.1 amperes, the reverse pulse electrolysis time is t2 and 6 ms; the electrolysis leveling time is 40 s.

[0078] The silver-plated copper wire product prepared in Example 1 was observed and evaluated. The winding test sample of the silver-plated copper wire was used to detect the defects. Figure 6 As shown, each strand was wound an average of fourteen times. After three sets of winding for each example sample, the samples were inspected using an HK830 optical microscope at 150° magnification. Figure 7 As shown.

[0079] Examples 2-7

[0080] The difference between Examples 2-7 and Example 1 is that the forward pulse current I1 and the reverse pulse current I2 are different, and their specific parameters are shown in Table 1.

[0081] Table 1. Ratio conditions of forward pulse current I1 and reverse pulse current I2 of electrolytic power supply 500 ohms and their test results in Examples 1-7

[0082]

[0083] The area ratio is the ratio of the area of ​​coating peeling off to the total area of ​​the coating. The calculation formula is: At 银层脱落面积 / At 银层总面积

[0084] Table 1 shows the ratio of forward pulse current I1 to reverse pulse current I2 and the test results of the electrolytic power supply 500 for Examples 1-7. As shown in Table 1, the forward pulse current I1 ranges from 2.7 to 1.6 amperes, and the reverse pulse current I2 ranges from 8.1 to 14.4 amperes, i.e., the I1 / I2 ratio is 1:3 to 1:9. Under these conditions, the copper wire samples obtained by electrolytic leveling have an arithmetic mean surface roughness Ra ranging from 113 to 121 nm. After further silver plating, the leveled copper wire samples, under a stable silver plating film thickness of 3.522 to 3.546 μm, were examined using an electron microscope at 140x magnification for both single needles and wound samples. The results showed that the surfaces were smooth and flat with no exposed copper, and the ratio of the plating peel area to the total area was... At 镀层脱落面积 / At 镀层总面积 The value was 0.0%; therefore, the overall judgment result was excellent. Example 4 shows a single copper wire and a wound sample magnified 140 times for testing. Figure 8 As shown, its silver-plated surface is smooth and flat with no exposed copper, and the ratio of the area of ​​plating peeling off to the total area of ​​plating is... At 镀层脱落面积 / At 镀层总面积 It is 0.0%.

[0085] Comparative Examples 1-6

[0086] The difference between Comparative Examples 1-6 and Example 1 is that the forward pulse current I1 and the reverse pulse current I2 are different, and their specific parameters are shown in Table 2.

[0087] Table 2. Ratio conditions and test results of forward pulse current I1 and reverse pulse current I2 in Comparative Examples 1-6

[0088]

[0089] The area ratio is the ratio of the area of ​​coating peeling off to the total area of ​​the coating. The calculation formula is: At 银层脱落面积 / At 银层总面积

[0090] The ratio conditions and test results of the forward pulse current I1 and reverse pulse current I2 for Comparative Examples 1-6 are shown in Table 2. Table 2 shows that the forward pulse current I1 ranges from 3.0 to 2.8 amps for Comparative Examples 1-3, and the reverse pulse current I2 ranges from 1.5 to 5.6 amps; the forward pulse current I1 ranges from 1.5 to 1.3 amps for Comparative Examples 4-6, and the reverse pulse current I2 ranges from 15 to 15.6 amps. That is, the I1 / I2 ratio for Comparative Examples 1-3 is 1:0.5 to 1:2, and the I1 / I2 ratio for Comparative Examples 4-6 is 1:10 to 1:12. Under these conditions, the arithmetic mean surface roughness Ra of the copper wire samples obtained through electrolytic treatment ranges from 129 to 137 nm. After further silver plating of the leveled copper wire samples, the silver-plated film thickness is 3.529 to 3.537 μm. The single needle and the wrapped sample were examined using an electron microscope at 140x magnification. The results showed that their surfaces had varying degrees of scratches and exposed copper. The ratio of the area of ​​plating loss to the total area was... At 镀层脱落面积 / At 镀层总面积 The percentage was 0.2% to 1.3%; therefore, the overall judgment result was unqualified; compared with the copper wire samples obtained from Example 1, both single strands and wound samples magnified 140 times, the results were as follows: Figure 9 As shown.

[0091] Examples 8-14

[0092] The difference between Examples 8-14 and Example 4 is that the forward pulse time t1 and the reverse pulse time t2 are different, and their specific parameters are shown in Table 3.

[0093] Table 3. Forward pulse time and reverse pulse time parameters and sample test results for Examples 8-14

[0094]

[0095] The area ratio is the ratio of the area of ​​coating peeling off to the total area of ​​the coating. The calculation formula is: At 银层脱落面积 / At 银层总面积

[0096] Table 3 shows that the forward pulse electrolysis time t1 in Examples 8-14 ranged from 5 to 6 milliseconds, and the reverse pulse electrolysis time t2 ranged from 30 to 55 milliseconds, i.e., the t1 / t2 ratio ranged from 5:1 to 11:1. Under these conditions, the arithmetic mean surface roughness Ra of the copper wire samples obtained ranged from 112 to 120 nm. After further silver plating on the leveled copper wire samples, the silver-plated film thickness was 3.522 to 3.546 μm. After the samples were wound, the single needle and the wound samples were examined using an electron microscope at 140x magnification. The results showed that the surface was smooth and flat with no exposed copper, and the ratio of the area of ​​plating peeling off to its total area was... At 镀层脱落面积 / At 镀层总面积 The value is 0.0%; therefore, its overall assessment result is excellent.

[0097] Comparative Examples 7-12

[0098] The difference between Comparative Examples 7-12 and Example 4 is that the forward pulse time t1 and the reverse pulse time t2 are different, and their specific parameters are shown in Table 4.

[0099] Table 4. Ratio of forward pulse electrolysis time t1 to reverse pulse electrolysis time t2 and test results for Comparative Example 7-12

[0100]

[0101] The area ratio is the ratio of the area of ​​coating peeling off to the total area of ​​the coating. The calculation formula is: At 银层脱落面积 / At 银层总面积

[0102] The ratios of forward pulse electrolysis time t1 to reverse pulse electrolysis time t2 in Comparative Examples 7-12 and the test results are shown in Table 4. Table 4 shows that the forward pulse electrolysis time t1 in Comparative Examples 7-9 ranges from 16 to 24 milliseconds, and the reverse pulse electrolysis time t2 ranges from 8 to 6 milliseconds; the forward pulse electrolysis time t1 in Comparative Examples 10-12 ranges from 16 to 24 milliseconds, and the reverse pulse electrolysis time t2 ranges from 8 to 6 milliseconds. That is, the t1 / t2 ratio in Comparative Examples 7-9 ranges from 2:1 to 4:1. In Examples 10-12, the t1 / t2 ratio ranged from 12:1 to 14:1. Under these conditions, the arithmetic mean surface roughness Ra of the copper wire samples obtained by electrolytic treatment ranged from 129 to 137 nm. After further silver plating on the leveled copper wire samples, the silver-plated film thickness was 3.529 to 3.537 μm. Electron microscopy at 140x magnification was used to examine single needles and wound samples, revealing varying degrees of scratches and exposed copper on their surfaces. The ratio of the area of ​​plating peeling off to its total area was... At 镀层脱落面积 / At 镀层总面积 The percentage is between 0.2% and 1.2%; therefore, the overall assessment result is unqualified.

[0103] Examples 15-21

[0104] The difference between Examples 15-21 and Example 11 is that the concentrations of cuprous cyanide, potassium cyanide, and triethanolamine in the leveling solution are different, and the specific parameters are shown in Table 5.

[0105] Table 5. Concentrations of cuprous cyanide, potassium cyanide, and triethanolamine in the leveling solutions of Examples 15-21, and sample test results.

[0106]

[0107] The area ratio is the ratio of the area of ​​coating peeling off to the total area of ​​the coating. The calculation formula is: At 银层脱落面积 / At 银层总面积

[0108] Table 5 shows that the copper content of cuprous cyanide in Examples 15-21 ranged from 9 to 21 g / L (calculated as copper), the complexing agent potassium cyanide ranged from 24 to 36 g / L, and the stabilizer triethanolamine ranged from 4.5 to 13.5 g / L. Under these conditions, the arithmetic mean surface roughness Ra of the copper wire samples obtained ranged from 113 to 121 nm. After further silver plating on the leveled copper wire samples, the silver plating film thickness was 3.528 to 3.543 μm. After the copper wire was wound, the single needle and the wound sample were examined using an electron microscope at 140x magnification. The results showed that the surface was smooth and flat with no exposed copper, and the ratio of the area of ​​plating peeling off to its total area was... At 镀层脱落面积 / At 镀层总面积 The value is 0.0%; therefore, its overall assessment result is excellent.

[0109] Comparative Examples 13-18

[0110] The difference between Comparative Examples 13-18 and Example 11 is that the concentrations of cuprous cyanide, potassium cyanide, and triethanolamine in the leveling solution are different, and the specific parameters are shown in Table 6.

[0111] Table 6. Concentrations of cuprous cyanide, potassium cyanide, and triethanolamine in the leveling solutions of Comparative Examples 13-18 and the test results of the samples.

[0112]

[0113] The area ratio is the ratio of the area of ​​coating peeling off to the total area of ​​the coating. The calculation formula is: At银层脱落面积 / At 银层总面积

[0114] Table 6 shows that the copper content of cuprous cyanide in Comparative Examples 13-15 ranged from 6 to 8 g / L, and that in Comparative Examples 16-18 ranged from 23 to 25 g / L; the amount of potassium cyanide used as a complexing agent in Comparative Examples 13-15 ranged from 18 to 22 g / L, and that in Comparative Examples 16-18 ranged from 38 to 42 g / L; the amount of triethanolamine used as a stabilizer in Comparative Examples 13-15 ranged from 3 to 4 g / L, and that in Comparative Examples 16-18 ranged from 14 to 15 g / L; under these conditions, the arithmetic mean surface roughness Ra of the copper wire samples obtained ranged from 134 to 141 nm; after further silver plating on the leveled copper wire samples, the silver-plated film thickness was 3.534 to 3.542 μm. Electron microscopy at 140x magnification was used to examine single copper wires and wound samples, revealing varying degrees of scratches and exposed copper on the surface. The ratio of the area of ​​plating peeling off to its total area was... At 镀层脱落面积 / At 镀层总面积 The percentage is 0.1% to 1.0%; therefore, the overall judgment result is unqualified.

[0115] Examples 22-28

[0116] The difference between Examples 22-28 and Example 18 is that the concentrations of the first leveling agent and the second leveling agent in the leveling solution are different.

[0117] Table 7. Concentrations of the first and second leveling agents in the leveling solutions of Examples 22-28 and test results of the samples.

[0118]

[0119] The area ratio is the ratio of the area of ​​coating peeling off to the total area of ​​the coating. The calculation formula is: At 银层脱落面积 / At 银层总面积

[0120] Table 5 shows that the dosage of the first leveling agent in Examples 22-28 was 4-10 g / L, and the dosage of the second leveling agent was 9-15 g / L. Under these conditions, the arithmetic mean surface roughness Ra of the copper wire samples obtained ranged from 113 to 122 nm. After further silver plating on the leveled copper wire samples, the silver plating film thickness was 3.531-3.542 μm. After the copper wire was wound, the results of the single needle and the wound sample were examined by electron microscopy at 140x magnification. The surface was smooth and flat with no exposed copper, and the ratio of the area of ​​plating peeling off to its total area was [missing information]. At 镀层脱落面积 / At镀层总面积 The value is 0.0%; therefore, its overall assessment result is excellent.

[0121] Comparative Examples 19-24

[0122] The difference between Comparative Examples 19-24 and Example 18 is that the concentrations of the first leveling agent and the second leveling agent in the leveling solution are different.

[0123] Table 8. Concentrations of the first and second leveling agents in the leveling solutions of Comparative Examples 19-24 and test results of the samples.

[0124]

[0125] The area ratio is the ratio of the area of ​​coating peeling off to the total area of ​​the coating. The calculation formula is: At 银层脱落面积 / At 银层总面积

[0126] Table 8 shows that the concentration range of the first leveling agent in the leveling solutions of Comparative Examples 19-21 was 1-3 g / L, and that of Comparative Examples 22-24 was 11-13 g / L; the concentration range of the second leveling agent in the leveling solutions of Comparative Examples 19-21 was 6-8 g / L, and that of Comparative Examples 22-24 was 16-18 g / L; the arithmetic mean surface roughness Ra of the copper wire samples obtained under these conditions ranged from 134 to 141 nm; after further silver plating on the leveled copper wire samples, the thickness of the silver-plated samples was 3.534-3.542 μm. Electron microscopy at 140x magnification was used to examine the single copper wire and the wound samples, revealing varying degrees of scratches and exposed copper on their surfaces. The ratio of the area of ​​plating peeling off to its total area was... At 镀层脱落面积 / At 镀层总面积 The percentage is between 0.2% and 1.3%; therefore, the overall judgment result is unqualified.

[0127] Example 29

[0128] The difference between Example 29 and Example 25 is that sodium cyanide is used instead of potassium cyanide.

[0129] Example 30

[0130] The difference between Example 30 and Example 25 is that 2-(2-hydroxyethylamino)-2-hydroxymethyl-1,3-propanediol with four hydroxyl groups is used as a stabilizer instead of triethanolamine, and tetramethylammonium hydroxide is used instead of tetraethylammonium hydroxide as the first leveling agent.

[0131] Example 31

[0132] The difference between Example 31 and Example 25 is that triisopropanolamine is used instead of the stabilizer triethanolamine, tetraoctylammonium hydroxide is used instead of the first leveling agent tetraethylammonium hydroxide, and N-tetradecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate is used instead of the second leveling agent N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate.

[0133] Example 32

[0134] The difference between Example 31 and Example 25 is that 2-di(2-hydroxyethyl)amino-2-hydroxymethyl-1,3-propanediol with five hydroxyl groups is used instead of the stabilizer triethanolamine, and hexadecyltrimethylammonium hydroxide is used instead of the first leveling agent tetraethylammonium hydroxide.

[0135] Example 33

[0136] The difference between Example 33 and Example 25 is that 2-hydroxymethyl-1,3-propanediol is used instead of the stabilizer triethanolamine, tetrabutylammonium hydroxide is used instead of the first leveling agent tetraethylammonium hydroxide, and N-[tris(hydroxymethyl)methyl]-3-aminopropanesulfonic acid is used instead of the second leveling agent N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate.

[0137] Example 34

[0138] The difference between Example 34 and Example 25 is that 2-benzylamino-2-hydroxymethyl-1,3-propanediol hydrochloride is used instead of the stabilizer triethanolamine, trimethylphenylammonium hydroxide is used instead of the first leveling agent tetraethylammonium hydroxide, and 3-[N-tris(hydroxymethyl)methylamine]-2-hydroxypropanesulfonic acid is used instead of the second leveling agent N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonic acid.

[0139] Table 9 Composition of the leveling solutions in Examples 29-34

[0140]

[0141] Table 10 Test results of silver-plated copper wire samples in Examples 29-34

[0142]

[0143] The area ratio is the ratio of the area of ​​coating peeling off to the total area of ​​the coating. The calculation formula is: At 银层脱落面积 / At 银层总面积

[0144] As shown in Table 10, the arithmetic mean surface roughness Ra of the copper wire samples obtained in Examples 29-34 ranges from 114 to 121 nm. After further silver plating on the leveled copper wire samples, the thickness of the silver-plated film obtained is 3.533-3.541 μm. Electron microscopy at 140x magnification was used to examine the single needle and the wound sample, respectively. The surface was smooth and flat with no exposed copper, and the ratio of the area of ​​plating peeling off to its total area was [not specified]. At 镀层脱落面积 / At 镀层总面积 The value was 0.0%; therefore, the overall assessment result was excellent.

[0145] Specifically, as can be seen below:

[0146] Example 29, using sodium cyanide instead of potassium cyanide in Example 25, achieved an excellent overall evaluation result, confirming that structurally similar complexing agents have the same function. Example 30, using 2-(2-hydroxyethylamino)-2-hydroxymethyl-1,3-propanediol (with four hydroxyalkyl groups) instead of the three-hydroxyalkyl stabilizer triethanolamine, and using tetramethylammonium hydroxide instead of the first leveling agent tetraethylammonium hydroxide, achieved an excellent overall evaluation result, confirming that stabilizers with more than three hydroxyalkyl groups in the compound have equivalent or better effects; it also confirms that structurally similar first leveling agents have equivalent functions. Example 31 uses triisopropanolamine instead of triethanolamine, tetraoctylammonium hydroxide instead of the first leveling agent tetraethylammonium hydroxide, and N-tetradecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate instead of the second leveling agent N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate. The overall evaluation result is excellent, confirming that stabilizers with similar structures have the same or better effects; it also confirms that the second leveling agent with similar structures has the same or better functions.

[0147] Example 32 uses 2-di(2-hydroxyethyl)amino-2-hydroxymethyl-1,3-propanediol with five hydroxyalkyl groups instead of the stabilizer triethanolamine, and hexadecyltrimethylammonium hydroxide instead of the first leveling agent tetraethylammonium hydroxide. The overall evaluation result is excellent, confirming that stabilizers with more than three hydroxyalkyl groups in the compound have equivalent or better effects; it also confirms that structurally similar first leveling agents have equivalent functions. Example 33 uses 2-hydroxymethyl-1,3-propanediol instead of the stabilizer triethanolamine, tetrabutylammonium hydroxide instead of the first leveling agent tetraethylammonium hydroxide, and N-[tris(hydroxymethyl)methyl]-3-aminopropanesulfonic acid instead of the second leveling agent N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate. The overall evaluation result is excellent, confirming that stabilizers with more than three hydroxyalkyl groups in the compound have equivalent or better effects; it also confirms that structurally similar second leveling agents have equivalent functions. Example 34 uses 2-benzylamino-2-hydroxymethyl-1,3-propanediol hydrochloride instead of the stabilizer triethanolamine, trimethylphenylammonium hydroxide instead of the first leveling agent tetraethylammonium hydroxide, and 3-[N-tris(hydroxymethyl)methylamine]-2-hydroxypropanesulfonic acid instead of the second leveling agent N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonic acid. The overall evaluation result is excellent, confirming that stabilizers with three or more hydroxyalkyl groups have equivalent or better effects; it also confirms that structurally similar first leveling agents have equivalent functions; furthermore, structurally similar second leveling agents have equivalent functions.

[0148] Comparative Example 25

[0149] The difference between Comparative Example 25 and Example 25 is that copper sulfate pentahydrate is used instead of cuprous cyanide.

[0150] Comparative Example 26

[0151] The difference between Comparative Example 26 and Example 25 is that tetraethylammonium cyanide is used instead of potassium cyanide.

[0152] Comparative Example 27

[0153] The difference between Comparative Example 27 and Example 25 is that tetraethylammonium hydroxide is used instead of the second leveling agent N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate.

[0154] Comparative Example 28

[0155] The difference between Comparative Example 28 and Example 25 is that diethanolamine is used instead of triethanolamine.

[0156] Comparative Example 29

[0157] The difference between Comparative Example 29 and Example 25 is that ammonium hydroxide is used instead of the first leveling agent, tetraethylammonium hydroxide.

[0158] Comparative Example 30

[0159] The difference between Comparative Example 30 and Example 25 is that sodium dodecyl sulfonate was used instead of the second leveling agent N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate.

[0160] Table 11 Composition of the leveling solutions in Comparative Examples 25-30

[0161]

[0162] Table 12 Test results of silver-plated copper wire samples in Comparative Examples 25-30

[0163]

[0164] The area ratio is the ratio of the area of ​​coating peeling off to the total area of ​​the coating. The calculation formula is: At 银层脱落面积 / At 银层总面积

[0165] Table 12 shows that the arithmetic mean surface roughness Ra of the copper wire samples obtained under the dual-pulse electrolytic leveling solution conditions in Comparative Examples 25-30 ranges from 133 to 141 nm. After further silver plating, the silver-plated samples have a film thickness of 3.533 to 3.540 μm. Electron microscopy at 140x magnification for both single copper wires and wound samples revealed varying degrees of scratches and exposed copper on their surfaces. The ratio of the area of ​​plating peeling off to its total area... At 镀层脱落面积 / At 镀层总面积 The percentages ranged from 2.7% to 3.5%; therefore, the overall assessment results were all unqualified.

[0166] Comparative Example 25, which used copper sulfate pentahydrate instead of cuprous cyanide, was deemed unqualified due to its use of a divalent copper salt instead of a monovalent copper salt, failing to achieve the expected results. Comparative Example 26, which used tetraethylammonium cyanide instead of potassium cyanide, was also deemed unqualified due to its use of an ammonium salt cyanide instead of an inorganic potassium cyanide, failing to achieve the expected results. Comparative Example 27, which used tetraethylammonium hydroxide as the first leveling agent instead of N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate as the second leveling agent, was deemed unqualified due to its use of an amine compound without hydroxyl groups instead of a hydroxylamine compound, failing to achieve the expected results. Comparative Example 28, which used diethanolamine instead of triethanolamine, was deemed unqualified due to its use of a compound containing two hydroxylamines instead of three, failing to achieve the expected results. Comparative Example 29, which used ammonium hydroxide instead of tetraethylammonium hydroxide as the first leveling agent, was deemed unqualified due to its use of ammonium hydroxide with a simpler molecular structure instead of four ethylammonium salts, failing to achieve the expected results. Comparative Example 30 used sodium dodecyl sulfonate to replace the second leveling agent N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate. The overall judgment result was unqualified, that is, the use of a sulfonate without hydroxymethyl groups to replace a sulfonate with three hydroxymethyl groups did not achieve the expected effect.

[0167] In summary, the copper wire leveling process based on the dual-pulse electrolytic power supply leveling solution of the present invention, i.e., the surface scratch defect leveling process, solves the difficult problem of micron-level scratch defects on the surface of metallic copper wires that is difficult to solve in existing electroplating pretreatment technologies.

[0168] The dual-pulse electrolytic leveling solution provided by this invention, through the synergistic and complementary functions of the first leveling agent and the second leveling agent during the cyclic switching of the positive and negative output terminals of the dual-pulse electrolytic power supply, selectively treats the micron-level scratch defect areas on the surface of the copper wire for pre-plating treatment. That is, it is a comprehensive technology of electrolytic leveling solution that preferentially electrolytically desorbs copper from concave areas and electrolytically strips copper from convex areas. This invention realizes the construction method and application objectives of the dual-pulse electrolytic power supply leveling solution, which is an effective process technology for filling concave areas and stripping convex areas.

[0169] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A leveling solution based on a dual-pulse electrolysis power supply, characterized in that, The solution comprises the following components: a copper salt with a concentration of 9-21 g / L (calculated as copper), a complexing agent of 24-36 g / L, a first leveling agent of 4-10 g / L, a second leveling agent of 9-15 g / L, a stabilizer of 4.5-13.5 g / L, and an electrolytic salt of 10-20 g / L. The solution pH is 12.0-14.

0. The copper salt is cuprous cyanide, the complexing agent is sodium cyanide and / or potassium cyanide, the first leveling agent is one or more of tetramethylammonium tetrafluoroborate, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, tetraoctylammonium hydroxide, trimethylphenylammonium hydroxide, and hexadecyltrimethylammonium hydroxide, and the second leveling agent is sodium trimethylolpropanesulfonate, 3-(N,N) The stabilizer comprises one or more of the following: N-dimethylhexadecylammonium) propanesulfonate, 3-(N-ethyl-3-methylaniline)-2-hydroxypropanesulfonate sodium salt, N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate, 3-[N-tris(hydroxymethyl)methylamine]-2-hydroxypropanesulfonic acid, tris(hydroxymethyl)methylaminopropanesulfonate sodium salt, N-tetradecyl-N,N-dimethyl-3-ammonium-1-propanesulfonate, and N-[tris(hydroxymethyl)methyl]-3-aminopropanesulfonic acid; the stabilizer comprises one or more of the following: triethanolamine, triisopropanolamine, 2-(2-hydroxyethylamino)-2-hydroxymethyl-1,3-propanediol, 2-di(2-hydroxyethyl)amino-2-hydroxymethyl-1,3-propanediol, triethanolamine borate, and 2-benzylamino-2-hydroxymethyl-1,3-propanediol hydrochloride; the electrolytic salt is sodium hydroxide or potassium hydroxide.

2. A method for smoothing scratch defects on the surface of copper wire, characterized in that, Includes the following steps: S1. The copper wire is subjected to ultrasonic degreasing, pure water cleaning, cathode electrolytic degreasing, pure water cleaning, anodic electrolytic degreasing, pure water cleaning, electrolytic acid activation, and pure water cleaning in sequence. S2. Prepare the leveling solution according to claim 1, place the continuously running copper wire in the leveling solution as the cathode, and connect it to the cathode output of the bidirectional pulse electrolysis power supply. The electrolytic copper plate below the copper wire serves as the anode and is connected to the anode output of the bidirectional pulse electrolysis power supply. The surface scratches of the copper wire are then electrolytically leveled. During electrolytic leveling, the ratio of the forward pulse current I1 to the reverse pulse current I2 is in the range of 1:3 to 1:9, and the ratio of the forward pulse electrolysis time t1 to the reverse pulse electrolysis time t2 is in the range of 5 to 11:1, thus obtaining the pre-treated copper wire product. S3. Place the copper wire pretreatment product obtained in step S2 into a silver plating device for silver plating to obtain silver-plated copper wire.

3. The leveling method according to claim 2, characterized in that, In step S2, the temperature of the leveling solution is 40~60℃.

4. The leveling method according to claim 2, characterized in that, In step S2, the forward pulse current I1 is 2.7~1.6 amperes and the reverse pulse current I2 is 8.1~14.4 amperes.

5. The leveling method according to claim 2, characterized in that, In step S2, the forward pulse electrolysis time is 30~55ms, the reverse pulse electrolysis time is 5~6ms, and the total electrolysis time is 35~61s.

6. The leveling method according to claim 2, characterized in that, In step S3, the electroplating solution for the silver plating process includes potassium silver cyanide as the main salt, with a concentration of 60 g / L (based on silver), sodium cyanide 170 g / L, Ag-903 plating starter 35 ml / L, pH 8.5, and a current density of 85 A / dm³ during silver plating. 2 The electroplating solution temperature was 45℃, and the electroplating time was 38 seconds; the target silver film thickness was set at 3.5μm.

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