Tinned copper wire with tinned layer not falling off and production process thereof

Abstract

This invention relates to the field of metal surface treatment technology, specifically to tin-plated copper wire for preventing tin plating layer peeling and its production process. The production process of the tin-plated copper wire for preventing tin plating layer peeling includes: preparing a nano-alumina-pillared nano-graphene sheet composite material; pretreatment; pulse electroplating; post-plating washing; and passivation sealing. This invention first disperses carboxyl-modified graphene in anhydrous ethanol, then adds an aluminum source precursor. Electrostatic self-assembly allows the aluminum source to be adsorbed onto the graphene sheet surface. After acid-catalyzed gelation, aging, and calcination heat treatment, a nano-alumina-pillared nano-graphene sheet composite material is obtained. This composite material is then added together with polytetrafluoroethylene (PTFE) particles to a mixed tin plating solution. After pulse electroplating of the pretreated copper wire, the nano-alumina-pillared nano-graphene sheets and PTFE particles synergistically improve the bonding force between the tin plating layer and the copper wire substrate, thereby effectively preventing tin plating layer peeling.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, specifically to tin-plated copper wire and its production process for preventing tin plating layer peeling. Background Technology

[0002] Tin-plated copper wire is a composite wire made of high-purity copper wire as the base material. Through processes such as electroplating, hot-dip plating, and chemical plating, a uniform, dense, and firmly bonded tin plating layer is formed on its surface. With its excellent conductivity, solderability, and corrosion resistance, it is widely used in automotive wiring harnesses, precision electronic components, industrial connectors, and other fields. As a key basic material in electronic components, power equipment, and precision connecting wires, the performance of the tin plating layer on the surface of tin-plated copper wire directly determines the conductivity reliability, corrosion resistance life, and long-term stability of the product.

[0003] Traditional tin-plated copper wires rely primarily on simple physical contact at the copper-tin interface, lacking a strong metallurgical bond and mechanical anchoring. Furthermore, the entire electroplating process suffers from incomplete interface activation, internal stress concentration, numerous plating defects, and easy interface failure. These shortcomings at each stage overlap, ultimately resulting in weak interfacial adhesion between the plating layer and the substrate. This makes the plating layer prone to peeling under bending, friction, and other conditions. The exposed copper substrate oxidizes rapidly, causing a surge in contact resistance, leading to localized overheating. This can result in signal distortion, circuit breaks, and even electrical fires under high-load conditions.

[0004] Furthermore, ordinary tin plating uses a direct current electroplating process, resulting in uneven tin ion deposition rates and significant concentration polarization. This leads to coarse tin grains, large grain boundary gaps, and low plating density. The surface inevitably contains microscopic defects such as pinholes, microcracks, and pitting, which become "rapid penetration channels" for corrosive media such as water molecules and oxygen. Corrosive media do not need to break through the physical shield of the tin layer and can directly reach the copper-tin interface through the defects, causing a large number of corrosion products to be generated at the interface. These products gradually replace the physical contact and the small amount of weak metallurgical bonding between the plating layer and the substrate. The adhesion of the plating layer drops rapidly as the bonding base is destroyed, resulting in the tin plating layer peeling off. Moreover, the core component of the tin plating solution, divalent tin ions, is easily oxidized and hydrolyzed. At the same time, there are many electrochemical side reactions and rapid accumulation of impurities, which ultimately lead to turbidity of the plating solution, formation of tin sludge, and a sharp drop in the effective concentration of tin ions, resulting in a significant decline in plating quality.

[0005] Therefore, it is necessary to propose a corrosion-resistant and solution-stable tin-plated copper wire and its production process to prevent tin plating layer peeling. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a tin-plated copper wire and its production process to prevent the tin plating layer from peeling off.

[0007] This invention provides a manufacturing process for tin-plated copper wire that prevents tin plating layer peeling, comprising the following steps: S1: Preparation of nano-alumina pillared nano-graphene sheet composite material S1.1: After vacuum drying, carboxyl-modified graphene sheets are added to anhydrous ethanol along with polyethylene glycol 400, ultrasonically stirred for 20-30 min, and preheated to 55-60℃ to obtain a carboxyl-modified graphene sheet dispersion. S1.2: Add aluminum isopropoxide to anhydrous ethanol at a ratio of 1 g: (2.9-3.1) mL, stir until completely dissolved, then add an aqueous ethanol solution, and continue stirring for 10-20 min to obtain the precursor solution. The amount of aqueous ethanol solution added is 28-30% of the volume of anhydrous ethanol, and the aqueous ethanol solution is prepared by mixing anhydrous ethanol and deionized water at a volume ratio of (6.2-6.4):1. S1.3: While stirring, the above precursor solution is added dropwise to the above carboxyl-modified graphene sheet dispersion at a rate of 2 mL / min. During this process, the mixture is kept warm and refluxed. After the addition is complete, the pH is adjusted to 3-3.5 with dilute hydrochloric acid solution. Then, the mixture is kept warm, stirred, and refluxed for 2-3 hours. Subsequently, it is allowed to stand at room temperature for 10-12 hours to obtain a gel. S1.4: Wash the above gel with anhydrous ethanol 2-3 times, air dry, freeze dry, then place it in a muffle furnace, heat it to 450-500℃ at 5℃ / min, and keep it at the temperature for 2-3 hours. Cool it to room temperature with the furnace, then grind it and pass it through a 100-mesh sieve to obtain a nano-alumina pillar-supported nano-graphene sheet composite material. S2: Preprocessing The copper wire substrate is immersed in degreasing solution, heated and stirred at 55-65℃ for 10-20 minutes, then rinsed with deionized water for 3-5 minutes, then immersed in pickling solution, ultrasonically treated for 3-5 minutes, and then rinsed with deionized water again for 3-5 minutes to obtain pretreated copper wire. S3: Pulse electroplating A mixed tin plating solution was prepared using stannous methanesulfonate, methanesulfonic acid, polytetrafluoroethylene particles, the above-mentioned nano-alumina pillar-supported nano-graphene sheet composite material, resveratrol solution, polyethylene glycol 400 and 2-mercaptobenzimidazole as raw materials. Then, the above-pretreated copper wire was subjected to pulse electroplating to obtain tin-plated copper wire. S4: Post-plating washing The tin-plated copper wire was immersed in deionized water for 3-5 minutes, then immersed in 1% dilute sulfuric acid for 3-5 seconds, and then immersed in deionized water for 3-5 minutes to obtain the washed copper wire. S5: Passivation sealing A passivation solution is prepared by dissolving sodium molybdate and disodium hydrogen phosphate in deionized water. A sealing solution is prepared by adding vinyltriethoxysilane to an ethanol solution. The washed copper wire is then dipped in the passivation solution and then dipped in the sealing solution to obtain tin-plated copper wire.

[0008] Furthermore, S3 specifically includes the following steps: S3.1: While stirring, add stannous methanesulfonate and methanesulfonic acid to deionized water and stir thoroughly until completely dissolved. Then add polytetrafluoroethylene particles and the nano-alumina pillar-supported nano-graphene sheet composite material prepared in step S1.4. After ultrasonic dispersion for 30-40 min, add resveratrol solution, polyethylene glycol 400 and 2-mercaptobenzimidazole. After stirring thoroughly to dissolve, adjust the pH to 1.1-1.3 with a pH adjuster, stir for 10-20 min, and then let stand for 1-2 h to obtain a mixed tin plating solution. S3.2: Using the pretreated copper wire obtained in step S2 as the cathode and the high-purity tin plate as the anode, the electroplating temperature is 30-34℃ and the current density is 3-3.5A / dm³. 2 The stirring speed is 300-400 rpm and the traction speed is 5-10 m / min. Pulse electroplating is performed on the surface of the pretreated copper wire to form a tin plating layer with a thickness of 8-10 μm, thus obtaining tin-plated copper wire.

[0009] Furthermore, S5 includes the following steps: S5.1: Add sodium molybdate and disodium hydrogen phosphate to deionized water at a ratio of (8-10)g:1g:(700-800)mL, stir thoroughly until completely dissolved, then add glacial acetic acid to adjust the pH to 4-4.5 to obtain the passivation solution; S5.2: Add vinyltriethoxysilane to a 10% ethanol solution at a volume ratio of 1:(40-45), stir and mix thoroughly, then add glacial acetic acid to adjust the pH to 4-4.5, continue stirring and hydrolyzing for 30-40 minutes, and then let stand for 10-20 minutes to obtain the sealing solution. S5.3: Immerse the washed copper wire obtained in step S4 into the above passivation solution, apply at 10 m / min for 5-7 s, rinse with water for 1 s and drain, then immerse in the above sealing solution, apply at 10 m / min for 6-8 s, drain for 4-6 min, and after drying, obtain tin-plated copper wire.

[0010] Furthermore, the carboxyl-modified graphene sheets have 5-10 layers, a sheet diameter of 0.5-2 μm, a carboxyl content ≥1.5 mmol / g, and a purity ≥99%.

[0011] Furthermore, the ratio of carboxyl-modified graphene sheets to anhydrous ethanol is 1g:(70-80)mL, and the amount of polyethylene glycol 400 added is 5-6% of the mass of the carboxyl-modified graphene sheets.

[0012] Furthermore, the volume ratio of the carboxyl-modified graphene sheet dispersion to the precursor solution is (3.3-3.5):1, and the dilute hydrochloric acid solution is prepared by mixing concentrated hydrochloric acid and anhydrous ethanol at a volume ratio of 1:25.

[0013] Furthermore, the degreasing solution includes 40 g / L sodium hydroxide, 20 g / L sodium carbonate, and the remainder is deionized water.

[0014] Furthermore, the pickling solution is prepared by mixing phosphoric acid with a mass concentration of 85% and concentrated sulfuric acid in a volume ratio of 1:3.

[0015] Furthermore, the mixed tin plating solution includes: 80-100 g / L stannous methanesulfonate, 120-150 g / L methanesulfonic acid, 2-3 g / L polytetrafluoroethylene particles, 4-5 g / L nano-alumina pillar-supported nano-graphene sheet composite material, 20-30 mg / L resveratrol solution, 6-8 g / L polyethylene glycol 400 and 0.1-0.3 g / L 2-mercaptobenzimidazole, wherein the resveratrol solution is prepared by mixing resveratrol and anhydrous ethanol at a ratio of 1 g: (90-100) mL.

[0016] The tin-plated copper wire for preventing tin plating from peeling off is produced by the manufacturing process of the tin-plated copper wire for preventing tin plating from peeling off as described in any of the above-mentioned items.

[0017] The present invention has the following advantages: 1. In this invention, carboxyl-modified graphene is first dispersed in anhydrous ethanol, then an aluminum source precursor is added. Electrostatic self-assembly allows the aluminum source to be adsorbed onto the graphene sheet surface. After acid-catalyzed gelation, aging, and calcination heat treatment, a nano-alumina-pillared graphene sheet composite material is obtained. Because the nano-alumina pillars increase the interlayer spacing of the graphene sheets, preventing aggregation, the nano-alumina-pillared graphene sheets can adhere parallel or obliquely to the copper wire surface during electroplating co-deposition, forming a nano-transition layer. During tin atom deposition, this transition layer is encapsulated and fills the interlayer gaps, forming a "tooth-like interlocking" mechanical structure. This significantly increases the contact area between the coating and the substrate, improving interfacial peel resistance. Furthermore, the nanoparticles can act as nucleation sites, refining tin grains, making the coating denser, reducing interfacial defects, and improving bonding strength. The polytetrafluoroethylene (PTFE) particles are low-modulus, flexible polymer particles with an extremely low coefficient of friction. After embedding into the coating, these particles can reduce friction during the deposition process. The internal friction of the nano-alumina-pillared graphene sheet composite material and polytetrafluoroethylene (PTFE) particles is released to relieve internal stress and prevent the coating from peeling off due to stress concentration. After pulse electroplating of the pretreated copper wire, the rigid support of the nano-alumina-pillared graphene sheet composite material bears the main internal stress during the electroplating process, avoiding overall deformation of the coating. The flexible buffer of the PTFE particles releases local stress concentration and eliminates the risk of microcracks in the rigid skeleton. The combination of the two can achieve "overall dispersion + local release" of the internal stress of the coating, fundamentally solving the problem of decreased adhesion of the electroplated coating caused by internal stress. In addition, the PTFE particles can be combined with the nano-alumina-pillared graphene sheet composite material through van der Waals forces, which helps the nano-alumina-pillared graphene sheet composite material to be stably dispersed in the plating solution and promotes uniform deposition of the coating. This achieves the effect of synergistically improving the bonding force between the tin plating layer and the copper wire substrate, thereby effectively preventing the tin plating layer from peeling off.

[0018] 2. In this invention, resveratrol is dissolved in anhydrous ethanol and then added to the mixed tin plating solution. Because the resveratrol molecule contains multiple phenolic hydroxyl groups, it has strong surface activity and can preferentially adsorb onto the active sites on the surface of the copper wire, temporarily blocking the rapid and disordered deposition of tin ions. This significantly refines the tin grains in the plating layer, increases the number of grain boundaries, and makes the plating layer more dense and uniform. This effectively reduces defects such as pinholes and microcracks, and allows the plating layer to more effectively block corrosive media from penetrating into the interior, thereby improving the corrosion resistance of the tin plating layer. In addition, as a natural antioxidant, resveratrol can help slow down the rate at which divalent tin ions in the plating solution are oxidized to tetravalent tin ions by air, thus helping to maintain the stability of the plating solution and extend its service life.

[0019] 3. In this invention, after tin plating and washing the copper wire surface, it is first immersed in a passivation solution containing sodium molybdate and disodium hydrogen phosphate. Under weakly acidic conditions, the tin plating surface will undergo slight dissolution, and subsequently, the molybdate ions react with the dissolved Sn²⁻. + The reaction, in conjunction with phosphate ions, generates a dense, amorphous composite passivation film on the coating surface. This film not only significantly improves the chemical corrosion resistance of the coating but also fills and covers microscopic defects, micropores, and grain boundaries in the tin plating layer, providing a more uniform and stable surface for subsequent silane treatment. Then, vinyltriethoxysilane hydrolysis sealing solution is applied to the passivation layer. The silanol groups generated by hydrolysis form strong covalent bonds with the metal hydroxyl groups on the passivation layer surface. The resulting silane film is a dense organic-inorganic hybrid layer that effectively blocks the penetration of corrosive media such as water molecules, oxygen, and chloride ions, preventing the intrusion of corrosive media at the interface between the coating and the copper wire substrate and causing copper corrosion, thereby achieving long-term anti-peeling of the coating. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the production process of the tin-plated copper wire used in an embodiment of the present invention to prevent the tin plating layer from peeling off. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention.

[0022] Example 1: Production process of tin-plated copper wire to prevent tin plating layer peeling, as follows: Figure 1 As shown, it includes the following steps: S1: Preparation of nano-alumina pillared nano-graphene sheet composite material S1.1: After vacuum drying, carboxyl-modified graphene sheets are added together with polyethylene glycol 400 to anhydrous ethanol, ultrasonically stirred for 20 min, and preheated to 55℃ to obtain a dispersion of carboxyl-modified graphene sheets. The ratio of carboxyl-modified graphene sheets to anhydrous ethanol is 1 g: 70 mL, and the amount of polyethylene glycol 400 added is 5% of the mass of carboxyl-modified graphene sheets. S1.2: Add aluminum isopropoxide to anhydrous ethanol at a ratio of 1g:2.9mL, stir until completely dissolved, then add an aqueous ethanol solution, and continue stirring for 10min to obtain a precursor solution. The amount of aqueous ethanol solution added is 28% of the volume of anhydrous ethanol, and the aqueous ethanol solution is prepared by mixing anhydrous ethanol and deionized water at a volume ratio of 6.2:1. S1.3: While stirring, the above precursor solution was added dropwise to the above carboxyl-modified graphene sheet dispersion at a rate of 2 mL / min. During this process, the mixture was kept warm and refluxed. After the addition was completed, the pH was adjusted to 3 with dilute hydrochloric acid solution. Then, the mixture was kept warm, stirred, and refluxed for 2 hours. Subsequently, it was allowed to stand at room temperature for 10 hours to obtain a gel. The volume ratio of the carboxyl-modified graphene sheet dispersion to the precursor solution was 3.3:1, and the dilute hydrochloric acid solution was prepared by mixing concentrated hydrochloric acid and anhydrous ethanol at a volume ratio of 1:25. S1.4: The above gel was washed twice with anhydrous ethanol, dried, freeze-dried, and then placed in a muffle furnace. The temperature was increased to 450°C at 5°C / min and kept at the temperature for 2 hours. The mixture was then cooled to room temperature in the furnace and then ground and passed through a 100-mesh sieve to obtain a nano-alumina pillar-supported nano-graphene sheet composite material. S2: Preprocessing The copper wire substrate is immersed in a degreasing solution, heated and stirred at 55°C for 10 minutes, then rinsed with deionized water for 3 minutes, then immersed in an acid pickling solution, ultrasonically treated for 3 minutes, and rinsed again with deionized water for 3 minutes to obtain pretreated copper wire. The degreasing solution includes 40 g / L sodium hydroxide, 20 g / L sodium carbonate, and the remainder is deionized water. The acid pickling solution is prepared by mixing 85% phosphoric acid and concentrated sulfuric acid in a volume ratio of 1:3. S3: Pulse electroplating S3.1: While stirring, add stannous methanesulfonate and methanesulfonic acid to deionized water and stir thoroughly until completely dissolved. Then add polytetrafluoroethylene particles and the nano-alumina pillared nano-graphene sheet composite material prepared in step S1.4. After ultrasonic dispersion for 30 min, add resveratrol solution, polyethylene glycol 400 and 2-mercaptobenzimidazole. After stirring thoroughly to dissolve, adjust the pH to 1.1 with a pH adjuster, stir for 10 min, and then let stand for 1 h to obtain a mixed tin plating solution. The mixed tin plating solution includes: 80 g / L stannous methanesulfonate, 120 g / L methanesulfonic acid, 2 g / L polytetrafluoroethylene particles, 4 g / L nano-alumina pillared nano-graphene sheet composite material, 20 mg / L resveratrol solution, 6 g / L polyethylene glycol 400 and 0.1 g / L 2-mercaptobenzimidazole. The resveratrol solution is prepared by mixing resveratrol and anhydrous ethanol at a ratio of 1 g: 90 mL. S3.2: Using the pretreated copper wire obtained in step S2 as the cathode and the high-purity tin plate as the anode, the electroplating temperature is 30℃ and the current density is 3A / dm³. 2 The stirring speed is 300 rpm and the traction speed is 5 m / min. Pulse electroplating is performed on the surface of the pretreated copper wire to form a tin plating layer with a thickness of 8 μm, thus obtaining tin-plated copper wire. S4: Post-plating washing The tin-plated copper wire was immersed in deionized water for 3 minutes, then immersed in 1% dilute sulfuric acid for 3 seconds, and then immersed in deionized water for 3 minutes to obtain the washed copper wire. S5: Passivation sealing S5.1: Add sodium molybdate and disodium hydrogen phosphate to deionized water at a ratio of 8g:1g:700mL, stir thoroughly until completely dissolved, then add glacial acetic acid to adjust the pH to 4 to obtain the passivation solution; S5.2: Add vinyltriethoxysilane to a 10% ethanol solution at a volume ratio of 1:40, stir and mix thoroughly, add glacial acetic acid to adjust the pH to 4, continue stirring and hydrolyzing for 30 min, and then let stand for 10 min to obtain the sealing solution. S5.3: Immerse the washed copper wire obtained in step S4 into the above passivation solution, apply it at 10 m / min for 5 s, rinse it with water for 1 s and drain it, then immerse it in the above sealing solution, apply it at 10 m / min for 6 s, drain it for 4 min, and after drying, tin-plated copper wire is obtained.

[0023] Example 2, the production process of tin-plated copper wire to prevent tin plating layer peeling, as follows: Figure 1 As shown, it includes the following steps: S1: Preparation of nano-alumina pillared nano-graphene sheet composite material S1.1: After vacuum drying, carboxyl-modified graphene sheets were added together with polyethylene glycol 400 to anhydrous ethanol, ultrasonically stirred for 25 min, and preheated to 57.5℃ to obtain a dispersion of carboxyl-modified graphene sheets. The ratio of carboxyl-modified graphene sheets to anhydrous ethanol was 1 g: 75 mL, and the amount of polyethylene glycol 400 added was 5.5% of the mass of the carboxyl-modified graphene sheets. S1.2: Add aluminum isopropoxide to anhydrous ethanol at a ratio of 1g:3mL, stir until completely dissolved, then add an aqueous ethanol solution, and continue stirring for 15min to obtain a precursor solution. The amount of aqueous ethanol solution added is 29% of the volume of anhydrous ethanol, and the aqueous ethanol solution is prepared by anhydrous ethanol and deionized water at a volume ratio of 6.3:1. S1.3: While stirring, the above precursor solution was added dropwise to the above carboxyl-modified graphene sheet dispersion at a rate of 2 mL / min. During this process, the mixture was kept warm and refluxed. After the addition was completed, the pH was adjusted to 3.3 with dilute hydrochloric acid solution. Then, the mixture was kept warm, stirred, and refluxed for 2.5 h. Subsequently, it was allowed to stand at room temperature for 11 h to obtain a gel. The volume ratio of the carboxyl-modified graphene sheet dispersion to the precursor solution was 3.4:1, and the dilute hydrochloric acid solution was prepared by mixing concentrated hydrochloric acid and anhydrous ethanol at a volume ratio of 1:25. S1.4: The above gel was washed twice with anhydrous ethanol, dried, freeze-dried, and then placed in a muffle furnace. The temperature was increased to 475°C at 5°C / min and calcined for 2.5 hours. The mixture was then cooled to room temperature in the furnace and then ground and passed through a 100-mesh sieve to obtain a nano-alumina pillar-supported nano-graphene sheet composite material. S2: Preprocessing The copper wire substrate is immersed in a degreasing solution, heated and stirred at 60°C for 15 minutes, then rinsed with deionized water for 4 minutes, then immersed in an acid pickling solution, ultrasonically treated for 4 minutes, and rinsed again with deionized water for 4 minutes to obtain pretreated copper wire. The degreasing solution consists of 40 g / L sodium hydroxide, 20 g / L sodium carbonate, and the remainder is deionized water. The acid pickling solution is prepared by mixing 85% phosphoric acid and concentrated sulfuric acid in a volume ratio of 1:3. S3: Pulse electroplating S3.1: While stirring, add stannous methanesulfonate and methanesulfonic acid to deionized water and stir thoroughly until completely dissolved. Then add polytetrafluoroethylene particles and the nano-alumina pillared nano-graphene sheet composite material prepared in step S1.4. After ultrasonic dispersion for 35 min, add resveratrol solution, polyethylene glycol 400 and 2-mercaptobenzimidazole. After stirring thoroughly to dissolve, adjust the pH to 1.2 with a pH adjuster, stir for 15 min, and then let stand for 1.5 h to obtain a mixed tin plating solution. The mixed tin plating solution includes: 90 g / L stannous methanesulfonate, 135 g / L methanesulfonic acid, 2.5 g / L polytetrafluoroethylene particles, 4.5 g / L nano-alumina pillared nano-graphene sheet composite material, 25 mg / L resveratrol solution, 7 g / L polyethylene glycol 400 and 0.2 g / L... 2-Mercaptobenzimidazole, resveratrol solution is prepared by mixing resveratrol and anhydrous ethanol at a ratio of 1g:95mL; S3.2: Using the pretreated copper wire obtained in step S2 as the cathode and the high-purity tin plate as the anode, the electroplating temperature is 32℃ and the current density is 3.3A / dm². 2 The stirring speed is 350 rpm and the traction speed is 7.5 m / min. Pulse electroplating is performed on the surface of the pretreated copper wire to form a tin plating layer with a thickness of 9 μm, thus obtaining tin-plated copper wire. S4: Post-plating washing The tin-plated copper wire was immersed in deionized water for 4 minutes, then immersed in 1% dilute sulfuric acid for 4 seconds, and then immersed in deionized water for 4 minutes to obtain the washed copper wire. S5: Passivation sealing S5.1: Add sodium molybdate and disodium hydrogen phosphate to deionized water at a ratio of 9g:1g:750mL, stir thoroughly until completely dissolved, then add glacial acetic acid to adjust the pH to 4.3 to obtain the passivation solution; S5.2: Add vinyltriethoxysilane to a 10% ethanol solution at a volume ratio of 1:42.5, stir and mix thoroughly, add glacial acetic acid to adjust the pH to 4.3, continue stirring and hydrolyzing for 35 min, and then let stand for 15 min to obtain the sealing solution. S5.3: Immerse the washed copper wire obtained in step S4 into the above passivation solution, apply it at 10 m / min for 6 s, rinse it with water for 1 s and drain it, then immerse it in the above sealing solution, apply it at 10 m / min for 7 s, drain it for 5 min, and after drying, you will get tin-plated copper wire.

[0024] Example 3, the production process of tin-plated copper wire to prevent tin plating layer peeling, as follows: Figure 1 As shown, it includes the following steps: S1: Preparation of nano-alumina pillared nano-graphene sheet composite material S1.1: After vacuum drying, carboxyl-modified graphene sheets are added together with polyethylene glycol 400 to anhydrous ethanol, ultrasonically stirred for 30 min, and preheated to 60℃ to obtain a carboxyl-modified graphene sheet dispersion. The ratio of carboxyl-modified graphene sheets to anhydrous ethanol is 1 g: 80 mL, and the amount of polyethylene glycol 400 added is 6% of the mass of the carboxyl-modified graphene sheets. S1.2: Add aluminum isopropoxide to anhydrous ethanol at a ratio of 1g:3.1mL, stir until completely dissolved, then add an aqueous ethanol solution, and continue stirring for 20min to obtain a precursor solution. The amount of aqueous ethanol solution added is 30% of the volume of anhydrous ethanol, and the aqueous ethanol solution is prepared by anhydrous ethanol and deionized water at a volume ratio of 6.4:1. S1.3: While stirring, the above precursor solution was added dropwise to the above carboxyl-modified graphene sheet dispersion at a rate of 2 mL / min. During this process, the mixture was kept warm and refluxed. After the addition was completed, the pH was adjusted to 3.5 with dilute hydrochloric acid solution. Then, the mixture was kept warm, stirred, and refluxed for 3 hours. Subsequently, it was allowed to stand at room temperature for 12 hours to obtain a gel. The volume ratio of the carboxyl-modified graphene sheet dispersion to the precursor solution was 3.5:1, and the dilute hydrochloric acid solution was prepared by mixing concentrated hydrochloric acid and anhydrous ethanol at a volume ratio of 1:25. S1.4: The above gel was washed three times with anhydrous ethanol, dried, freeze-dried, and then placed in a muffle furnace. The temperature was increased to 500°C at 5°C / min and kept at that temperature for 3 hours. The mixture was then cooled to room temperature in the furnace and then ground and passed through a 100-mesh sieve to obtain a nano-alumina pillar-supported nano-graphene sheet composite material. S2: Preprocessing The copper wire substrate is immersed in a degreasing solution, heated and stirred at 65°C for 20 minutes, then rinsed with deionized water for 5 minutes, then immersed in an acid pickling solution, ultrasonically treated for 5 minutes, and rinsed again with deionized water for 5 minutes to obtain pretreated copper wire. The degreasing solution consists of 40 g / L sodium hydroxide, 20 g / L sodium carbonate, and the remainder is deionized water. The acid pickling solution is prepared by mixing 85% phosphoric acid and concentrated sulfuric acid in a volume ratio of 1:3. S3: Pulse electroplating S3.1: While stirring, add stannous methanesulfonate and methanesulfonic acid to deionized water and stir thoroughly until completely dissolved. Then add polytetrafluoroethylene particles and the nano-alumina pillared nano-graphene sheet composite material prepared in step S1.4. After ultrasonic dispersion for 40 min, add resveratrol solution, polyethylene glycol 400 and 2-mercaptobenzimidazole. After stirring thoroughly to dissolve, adjust the pH to 1.3 with a pH adjuster, stir for 20 min, and then let stand for 2 h to obtain a mixed tin plating solution. The mixed tin plating solution includes: 100 g / L stannous methanesulfonate, 150 g / L methanesulfonic acid, 3 g / L polytetrafluoroethylene particles, 5 g / L nano-alumina pillared nano-graphene sheet composite material, 30 mg / L resveratrol solution, 8 g / L polyethylene glycol 400 and 0.3 g / L 2-mercaptobenzimidazole. The resveratrol solution is prepared by mixing resveratrol and anhydrous ethanol at a ratio of 1 g: 100 mL. S3.2: Using the pretreated copper wire obtained in step S2 as the cathode and the high-purity tin plate as the anode, the electroplating temperature is 34℃ and the current density is 3.5A / dm³. 2 The stirring speed is 400 rpm and the traction speed is 10 m / min. Pulse electroplating is performed on the surface of the pretreated copper wire to form a tin plating layer with a thickness of 10 μm, thus obtaining tin-plated copper wire. S4: Post-plating washing The tin-plated copper wire was immersed in deionized water for 5 minutes, then immersed in 1% dilute sulfuric acid for 5 seconds, and then immersed in deionized water for 5 minutes to obtain the washed copper wire. S5: Passivation sealing S5.1: Add sodium molybdate and disodium hydrogen phosphate to deionized water at a ratio of 10g:1g:800mL, stir thoroughly until completely dissolved, then add glacial acetic acid to adjust the pH to 4.5 to obtain the passivation solution; S5.2: Add vinyltriethoxysilane to a 10% ethanol solution at a volume ratio of 1:45, stir and mix thoroughly, add glacial acetic acid to adjust the pH to 4.5, continue stirring and hydrolyzing for 40 min, and then let stand for 20 min to obtain the sealing solution. S5.3: Immerse the washed copper wire obtained in step S4 into the above passivation solution, apply it at 10 m / min for 7 s, rinse it with water for 1 s and drain it, then immerse it in the above sealing solution, apply it at 10 m / min for 8 s, drain it for 6 min, and after drying, tin-plated copper wire is obtained.

[0025] Comparative Example 1 differs from Example 1 in that the nano-alumina pillar-supported nano-graphene sheet composite material in step S3.1 is removed.

[0026] Comparative Example 2 differs from Example 1 in that the nano-alumina pillar-supported nano-graphene sheet composite material in step S3.1 is replaced with an equal amount of polytetrafluoroethylene particles.

[0027] Comparative Example 3 differs from Example 1 in that the polytetrafluoroethylene particles in step S3.1 are replaced with an equal amount of nano-alumina pillar-supported nano-graphene sheet composite material.

[0028] Comparative Example 4 differs from Example 1 in that the polytetrafluoroethylene particles and nano-alumina pillar-supported nano-graphene sheet composite material in step S3.1 are removed.

[0029] Comparative Example 5 differs from Example 1 in that the resveratrol solution in step S3.1 is removed.

[0030] Comparative Example 6 differs from Example 1 in that: in step S5.3, only the passivation liquid is applied, and the sealing liquid is not applied.

[0031] Comparative Example 7 differs from Example 1 in that: in step S5.3, only the sealing liquid is applied, and the passivation liquid is not applied.

[0032] Comparative Example 8 differs from Example 1 in that step S5 is removed, i.e., the passivation solution and sealing solution are not applied.

[0033] Test example: Test 1: The tin-plated surfaces of the washed copper wires prepared in Examples 1-3 and Comparative Examples 1-4 were tightly adhered with 3M strong adhesive tape, and then quickly peeled off. The surface of the tape was observed to see if there was any tin-plated residue. The rating was: 0 (no residue), 1 (slight residue), 2 (obvious residue), and 3 (large amount of residue). The results are shown in Table 1.

[0034] Table 1: Adhesion Test Results

[0035] As shown in Table 1, the bonding strength of the tin plating layer of the washed copper wire obtained in Comparative Example 1 without the addition of nano-alumina pillar-supported nano-graphene sheet composite material is worse than that in Example 1. It can be seen that by first dispersing carboxyl-modified graphene in anhydrous ethanol, then adding aluminum source precursor, using electrostatic self-assembly to adsorb the aluminum source onto the surface of the graphene sheet, and then undergoing acid-catalyzed gelation, aging and calcination heat treatment, nano-alumina pillar-supported nano-graphene sheet composite material is obtained. After adding it to the mixed tin plating solution, the bonding strength between the plating layer and the substrate can be greatly increased. In Comparative Examples 2 and 3, when only one of the polytetrafluoroethylene (PTFE) or nano-alumina-pillared nano-graphene sheet composite materials was added to the mixed tin plating solution, the adhesion of the tin plating layer of the prepared washed copper wire was stronger than that of Comparative Example 4, but still worse than that of Example 1. This shows that when the nano-alumina-pillared nano-graphene sheet composite material and PTFE particles are added together to the mixed tin plating solution and the pretreated copper wire is pulsed electroplated, the nano-alumina pillars can synergistically improve the adhesion between the nano-graphene sheet and the PTFE particles, thereby effectively preventing the tin plating layer from peeling off.

[0036] Test 2: According to GB / T10125-2021, the washed copper wires prepared in Examples 1-3 and Comparative Example 5 were subjected to a neutral salt spray test. The salt spray concentration was 5% sodium chloride solution, the pH was 6.5-7.2, and the temperature was 35℃. The spraying was continuous, and the time when the first white rust appeared on the coating was recorded. Each group was tested 3 times, and the average value was taken. The results are shown in Table 2.

[0037] Table 2: Test results of time to first appearance of white rust on the coating

[0038] Test 3: Slowly add 30wt% hydrogen peroxide solution to the mixed tin plating solution prepared in Examples 1-3 and Comparative Example 5. Record the volume of hydrogen peroxide solution consumed when the mixed tin plating solution becomes turbid. The more volume of hydrogen peroxide solution consumed, the better the stability of the mixed tin plating solution. Repeat the test 3 times for each group and take the average value. The results are shown in Table 3.

[0039] Table 3: Stability Test Results of Mixed Tin Plating Solution

[0040] As shown in Tables 2 and 3, in Comparative Example 5 without the addition of resveratrol solution, the time for the first appearance of white rust on the tin-plated layer of the washed copper wire was significantly faster than in Example 1. Furthermore, the volume of hydrogen peroxide solution consumed in the mixed tin plating solution in Comparative Example 5 was also smaller than that in Example 1. This demonstrates that by dissolving resveratrol in anhydrous ethanol and then adding it to the mixed tin plating solution, the plating layer can be made denser and more uniform, effectively reducing defects such as pinholes and microcracks. This allows the plating layer to more effectively block corrosive media from penetrating into the interior, thereby improving the corrosion resistance of the tin plating layer. In addition, it helps maintain the stability of the plating solution and extends its service life.

[0041] Test 4: According to GB / T10125-2021, the tin-plated copper wires prepared in Examples 1-3 and Comparative Examples 6-8 were subjected to neutral salt spray tests. The salt spray concentration was 5% NaCl solution, the pH was 6.5-7.2, and the temperature was 35℃. Continuous spraying was carried out, and the time of first appearance of red rust (corrosion of copper substrate and failure of coating) was recorded. The test was repeated 3 times, and the average value was taken. The results are shown in Table 4.

[0042] Table 4: Test Results of Time to First Appearance of Red Rust

[0043] As shown in Table 4, in Comparative Example 8, where neither passivation nor sealing was performed, the time for the first appearance of red rust on the tin-plated copper wire was significantly faster than in Example 1. While in Comparative Example 6, where only passivation was performed without sealing, and in Comparative Example 7, where only sealing was performed without passivation, the time for the first appearance of red rust on the tin-plated copper wire was slower than in Comparative Example 8, it was still faster than in Comparative Example 1. This demonstrates that after tin plating and washing the copper wire surface, immersing it in a passivation solution containing sodium molybdate and disodium hydrogen phosphate generates a dense, amorphous composite compound passivation film on the plating surface. It can not only significantly improve the chemical corrosion resistance of the coating, but also fill and cover the microscopic defects, micropores and grain boundaries of the tin plating layer, providing a more uniform and stable surface for subsequent silane treatment. Then, vinyltriethoxysilane hydrolytic sealing solution is applied to the passivation layer. The resulting silane film is a dense organic-inorganic hybrid layer that can effectively block the penetration of corrosive media such as water molecules, oxygen, and chloride ions, preventing the corrosive media from invading at the interface between the coating and the copper wire substrate and causing copper corrosion, thereby achieving long-term anti-peeling of the coating.

[0044] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Parts not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A manufacturing process for tin-plated copper wire to prevent tin plating layer peeling, characterized in that, Includes the following steps: S1: Preparation of nano-alumina pillared nano-graphene sheet composite material S1.1: After vacuum drying, carboxyl-modified graphene sheets are added to anhydrous ethanol along with polyethylene glycol 400, ultrasonically stirred for 20-30 min, and preheated to 55-60℃ to obtain a carboxyl-modified graphene sheet dispersion. S1.2: Add aluminum isopropoxide to anhydrous ethanol at a ratio of 1 g: (2.9-3.1) mL, stir until completely dissolved, then add an aqueous ethanol solution, and continue stirring for 10-20 min to obtain the precursor solution. The amount of aqueous ethanol solution added is 28-30% of the volume of anhydrous ethanol, and the aqueous ethanol solution is prepared by mixing anhydrous ethanol and deionized water at a volume ratio of (6.2-6.4):

1. S1.3: While stirring, the above precursor solution is added dropwise to the above carboxyl-modified graphene sheet dispersion at a rate of 2 mL / min. During this process, the mixture is kept warm and refluxed. After the addition is complete, the pH is adjusted to 3-3.5 with dilute hydrochloric acid solution. Then, the mixture is kept warm, stirred, and refluxed for 2-3 hours. Subsequently, it is allowed to stand at room temperature for 10-12 hours to obtain a gel. S1.4: Wash the above gel with anhydrous ethanol 2-3 times, air dry, freeze dry, then place it in a muffle furnace, heat it to 450-500℃ at 5℃ / min, and keep it at the temperature for 2-3 hours. Cool it to room temperature with the furnace, then grind it and pass it through a 100-mesh sieve to obtain a nano-alumina pillar-supported nano-graphene sheet composite material. S2: Preprocessing The copper wire substrate is immersed in degreasing solution, heated and stirred at 55-65℃ for 10-20 minutes, then rinsed with deionized water for 3-5 minutes, then immersed in pickling solution, ultrasonically treated for 3-5 minutes, and then rinsed with deionized water again for 3-5 minutes to obtain pretreated copper wire. S3: Pulse electroplating A mixed tin plating solution was prepared using stannous methanesulfonate, methanesulfonic acid, polytetrafluoroethylene particles, the above-mentioned nano-alumina pillar-supported nano-graphene sheet composite material, resveratrol solution, polyethylene glycol 400 and 2-mercaptobenzimidazole as raw materials. Then, the above-pretreated copper wire was subjected to pulse electroplating to obtain tin-plated copper wire. S4: Post-plating washing The tin-plated copper wire was immersed in deionized water for 3-5 minutes, then immersed in 1% dilute sulfuric acid for 3-5 seconds, and then immersed in deionized water for 3-5 minutes to obtain the washed copper wire. S5: Passivation sealing A passivation solution is prepared by dissolving sodium molybdate and disodium hydrogen phosphate in deionized water. A sealing solution is prepared by adding vinyltriethoxysilane to an ethanol solution. The washed copper wire is then dipped in the passivation solution and then dipped in the sealing solution to obtain tin-plated copper wire.

2. The production process of the tin-plated copper wire for preventing tin plating layer peeling according to claim 1, characterized in that, S3 includes the following steps: S3.1: While stirring, add stannous methanesulfonate and methanesulfonic acid to deionized water and stir thoroughly until completely dissolved. Then add polytetrafluoroethylene particles and the nano-alumina pillar-supported nano-graphene sheet composite material prepared in step S1.

4. After ultrasonic dispersion for 30-40 min, add resveratrol solution, polyethylene glycol 400 and 2-mercaptobenzimidazole. After stirring thoroughly to dissolve, adjust the pH to 1.1-1.3 with a pH adjuster, stir for 10-20 min, and then let stand for 1-2 h to obtain a mixed tin plating solution. S3.2: Using the pretreated copper wire obtained in step S2 as the cathode and the high-purity tin plate as the anode, the electroplating temperature is 30-34℃ and the current density is 3-3.5A / dm³. 2 The stirring speed is 300-400 rpm and the traction speed is 5-10 m / min. Pulse electroplating is performed on the surface of the pretreated copper wire to form a tin plating layer with a thickness of 8-10 μm, thus obtaining tin-plated copper wire.

3. The production process of the tin-plated copper wire for preventing tin plating layer peeling according to claim 2, characterized in that, S5 includes the following steps: S5.1: Add sodium molybdate and disodium hydrogen phosphate to deionized water at a ratio of (8-10)g:1g:(700-800)mL, stir thoroughly until completely dissolved, then add glacial acetic acid to adjust the pH to 4-4.5 to obtain the passivation solution; S5.2: Add vinyltriethoxysilane to a 10% ethanol solution at a volume ratio of 1:(40-45), stir and mix thoroughly, then add glacial acetic acid to adjust the pH to 4-4.5, continue stirring and hydrolyzing for 30-40 minutes, and then let stand for 10-20 minutes to obtain the sealing solution. S5.3: Immerse the washed copper wire obtained in step S4 into the above passivation solution, apply at 10 m / min for 5-7 s, rinse with water for 1 s and drain, then immerse in the above sealing solution, apply at 10 m / min for 6-8 s, drain for 4-6 min, and after drying, obtain tin-plated copper wire.

4. The production process of the tin-plated copper wire for preventing tin plating layer peeling according to claim 1, characterized in that, The carboxyl-modified graphene sheets have 5-10 layers, a sheet diameter of 0.5-2 μm, a carboxyl content ≥1.5 mmol / g, and a purity ≥99%.

5. The production process of the tin-plated copper wire for preventing tin plating layer peeling according to claim 1, characterized in that, The ratio of carboxyl-modified graphene sheets to anhydrous ethanol is 1g:(70-80)mL, and the amount of polyethylene glycol 400 added is 5-6% of the mass of the carboxyl-modified graphene sheets.

6. The production process of the tin-plated copper wire for preventing tin plating layer peeling according to claim 1, characterized in that, The volume ratio of the carboxyl-modified graphene sheet dispersion to the precursor solution is (3.3-3.5):1, and the dilute hydrochloric acid solution is prepared by mixing concentrated hydrochloric acid and anhydrous ethanol at a volume ratio of 1:

25.

7. The production process of the tin-plated copper wire for preventing tin plating layer peeling according to claim 1, characterized in that, The degreasing solution consists of 40 g / L sodium hydroxide, 20 g / L sodium carbonate, and the remainder is deionized water.

8. The production process of the tin-plated copper wire for preventing tin plating layer peeling according to claim 1, characterized in that, The pickling solution is prepared by mixing phosphoric acid (85% by mass) and concentrated sulfuric acid in a volume ratio of 1:

3.

9. The production process of the tin-plated copper wire for preventing tin plating layer peeling according to claim 2, characterized in that, The mixed tin plating solution includes: 80-100 g / L stannous methanesulfonate, 120-150 g / L methanesulfonic acid, 2-3 g / L polytetrafluoroethylene particles, 4-5 g / L nano-alumina pillar-supported nano-graphene sheet composite material, 20-30 mg / L resveratrol solution, 6-8 g / L polyethylene glycol 400 and 0.1-0.3 g / L 2-mercaptobenzimidazole, wherein the resveratrol solution is prepared by mixing resveratrol and anhydrous ethanol at a ratio of 1 g: (90-100) mL.

10. A tin-plated copper wire for preventing tin plating layer peeling, characterized in that, It is produced by the manufacturing process of tin-plated copper wire for preventing tin plating layer peeling as described in any one of claims 1-9.

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