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CN-122013192-A - Stripping solution and method for stripping tin-containing coating

CN122013192ACN 122013192 ACN122013192 ACN 122013192ACN-122013192-A

Abstract

The invention provides a stripping solution which comprises, by weight, 10-30% of sulfuric acid, 0.5-1.5% of stannous sulfate, 0.5-2.5% of sodium sulfate, 0.5-2.5% of a complexing agent, 0.1-0.5% of an antioxidant, 1-3% of a copper protection agent, 0.1-0.5% of an additive and the balance of water, wherein the complexing agent is any one or two of sulfamic acid, methanesulfonic acid, phenolsulfonic acid and citric acid, the antioxidant is any one of resorcinol, hydroquinone and ascorbic acid, the copper protection agent is a corrosion inhibition microsphere with a core-shell structure, the corrosion inhibition microsphere with a core-shell structure takes hollow silicon dioxide as a core, the surface of the corrosion inhibition microsphere is grafted with benzotriazole, the outer layer of the corrosion inhibition microsphere is wrapped with a layer of pH sensitive polymethacrylic shell, the particle size of which is controlled to be 5-20 mu m, and the additive is any one of polyethylene glycol and gelatin. According to the invention, by optimizing the formula of the stripping solution, particularly upgrading the copper-protecting agent system, the high-efficiency and nondestructive stripping of the tin-containing plating layer is realized, the recovery purity of tin and copper is improved, and the service life of the stripping solution is prolonged.

Inventors

  • TIAN BAOLONG
  • WANG HAO
  • LIU HUI
  • YANG BAOYAN
  • YANG GUODONG

Assignees

  • 苏州金易得环保科技有限公司

Dates

Publication Date
20260512
Application Date
20260212

Claims (8)

  1. 1. The stripping solution is characterized by comprising the following components in percentage by weight: 10-30% of sulfuric acid 0.5 To 1.5 percent of stannous sulfate 0.5 To 2.5 percent of sodium sulfate Complexing agent accounting for 0.5 to 2.5 percent 0.1 To 0.5 percent of antioxidant 1-3% Of copper-protecting agent 0.1 To 0.5 percent of additive The balance being water; Wherein the complexing agent is any one or two of sulfamic acid, methanesulfonic acid, phenolsulfonic acid and citric acid; The antioxidant is any one of resorcinol, hydroquinone and ascorbic acid; The copper-protecting agent is a core-shell corrosion inhibition microsphere, the core-shell corrosion inhibition microsphere takes hollow silicon dioxide as a core, benzotriazole is grafted on the surface of the core-shell corrosion inhibition microsphere, a layer of pH sensitive polymethacrylic hydrogel shell is wrapped on the outer layer of the core-shell corrosion inhibition microsphere, and the particle size is controlled to be 5-20 mu m; The additive is any one of polyethylene glycol and gelatin.
  2. 2. The tin stripping liquid according to claim 1, wherein the preparation method of the core-shell corrosion inhibition microsphere comprises the following steps: s11, mixing tetraethoxysilane, hydrochloric acid, absolute ethyl alcohol and water according to a molar ratio of 1:1:80:4 to obtain sol, immersing pollen in the sol, taking out and drying, and performing heat treatment to obtain a hollow microsphere core; S12, adding the hollow microsphere core into water, performing ultrasonic dispersion for 5-8 min, adding 3-aminopropyl triethoxysilane, stirring at 50-60 ℃ for reaction for 1-2h, adding benzotriazole, and continuing stirring for reaction for 2-3 h to obtain BTA modified hollow microspheres; And S13, adding the BTA modified hollow microsphere into deionized water, performing ultrasonic dispersion to form a suspension, adding a polymethacrylic acid monomer, N-methylene bisacrylamide and ammonium persulfate into the suspension, introducing nitrogen to remove air, performing polymerization reaction for 1-1.5 h at 60-70 ℃, forming a layer of polymethacrylic acid hydrogel shell with the thickness of 0.1-0.5 mu m on the outer layer of the microsphere, and performing centrifugal separation, washing and vacuum drying after the reaction is finished to obtain the corrosion inhibition microsphere with the core-shell structure.
  3. 3. The tin stripping liquid according to claim 1, wherein the tin stripping liquid further comprises 0.05-0.15% of rare earth oxide and 0.03-0.08% of aminotrimethylene phosphonic acid, and the rare earth oxide is any one of cerium oxide and lanthanum oxide.
  4. 4. A method for stripping tin-containing plating layer, which is characterized in that the tin stripping liquid according to any one of claims 1-3 is used for carrying out surface tin stripping treatment on tin plating materials.
  5. 5. The method for stripping tin-containing plating layer according to claim 4, wherein tin plating materials to be stripped are placed in titanium blue, the titanium blue with tin parts to be stripped is immersed in the optimized stripping liquid to ensure that the tin parts to be stripped are completely immersed, a rectifier is connected to a positive electrode, a negative electrode is connected to an iron plate, current is controlled in a steady-flow mode, when tin-copper alloy is stripped, voltage is obviously increased, a PLC control system is used for rapidly adjusting the rectifier to a steady-pressure mode, the voltage is controlled to be 2.8-3.2V, metallic tin is finally obtained on the iron plate, and bright metallic copper is obtained in the titanium blue.
  6. 6. The tin stripping liquid according to claim 2, wherein the temperature of the heat treatment in the step S11 is 500-600 ℃ and the time is 2-3 hours.
  7. 7. The tin stripping liquid according to claim 2, wherein the 3-aminopropyl triethoxysilane in the step S12 accounts for 5-10% of the mass of the hollow microspheres, and the benzotriazole accounts for 15-25% of the mass of the hollow microspheres.
  8. 8. The tin stripping liquid according to claim 2, wherein the amount of the polymethacrylic acid monomer in the step S14 is 20-30% of the mass of the BTA modified hollow microsphere, the amount of the cross-linking agent is 1-2% of the mass of the polymethacrylic acid monomer, and the amount of the ammonium persulfate is 0.5-1% of the mass of the polymethacrylic acid monomer.

Description

Stripping solution and method for stripping tin-containing coating Technical Field The invention relates to the technical field of metal coating stripping, in particular to a stripping solution and a method for stripping a tin-containing coating. Background The tin-containing coating is widely applied to industries such as electronics, hardware, electroplating and the like and is used for improving the corrosion resistance, weldability and decoration of products. In the production process of the product, the problems of uneven plating thickness, flaws, disqualification and the like often occur, the tin-containing plating layer needs to be removed and then electroplated again, and meanwhile, the recovery treatment of the waste tin-containing plating layer product also needs to be an efficient tin removing process, so that the recycling of noble metals such as tin, copper and the like is realized. The existing tin stripping process mainly comprises two major types of chemical tin stripping and electrochemical tin stripping, wherein the chemical tin stripping process has the advantages of low tin stripping speed, high tin-copper separation difficulty, short service life of stripping liquid, easiness in generating a large amount of tin-containing waste residues and waste liquid, easiness in corroding matrix copper and causing light loss and damage of the matrix, the electrochemical tin stripping process has the advantages of improving tin stripping efficiency, low process control precision, difficulty in accurate capturing of voltage mutation, easiness in occurrence of over-stripping (corrosion of matrix copper) or incomplete stripping, low tin deposition purity, poor brightness of the copper matrix in the process of stripping, additional separation and purification procedures for subsequent resource recovery, complicated flow and higher cost. In addition, in the existing stripping solution formula, the synergistic effect of the complexing agent, the antioxidant and the copper protection agent is insufficient, so that the stripping solution is easy to be poor in stability, turbidity and failure are easy to occur after long-term use, the copper protection effect is limited, the bright retention of a copper matrix cannot be realized, meanwhile, the existing process does not consider the dynamic matching of parameters such as temperature, current density and the like in the stripping process, and the stripping effect and the resource recovery efficiency are further influenced. The copper-protecting agent is characterized in that the existing copper-protecting agents (such as benzotriazole BTA and methylbenzotriazole) are molecular dispersion type, and have the obvious technical defects that firstly, the copper-protecting agent molecules are adhered to the surface of a copper matrix in a physical adsorption mode, desorption and loss are easy to occur under strong stirring and large current impact in a deplating process, so that the copper-protecting effect is not durable, corrosion and light loss phenomena still occur on the copper matrix after long-term deplating, secondly, the surface of the copper matrix which is slightly pitted and roughened can only be covered by the traditional molecular copper-protecting agent, the defect part cannot be repaired in a targeted way, the surface evenness of the copper matrix after deplating is insufficient, the subsequent re-electroplating quality is affected, and thirdly, the molecular dispersion copper-protecting agent is easy to be carried out by deplating liquid and is lost with waste liquid, so that the copper-protecting agent utilization rate is reduced, the production cost is increased, and the waste liquid treatment burden is increased. Aiming at the defects of the prior art, development of a process method for removing a tin-containing coating, which has high tin removing efficiency, no damage to a copper matrix, high tin and copper recovery purity, good stability of a stripping solution and strong process controllability, is needed, and particularly solves the problems that the traditional copper-protecting agent is not durable in copper protection and has weak repairing capability, improves the practicability and economy of the process, and meets the requirements of industrial mass production and resource recovery. Disclosure of Invention The invention aims to provide a tin stripping solution and a process method for stripping a tin-containing coating by using the tin stripping solution, particularly to upgrade a copper-protecting agent system, so that the tin-containing coating can be efficiently and nondestructively stripped, the recovery purity of tin and copper can be improved, the service life of the tin and copper stripping solution can be prolonged, and the problems of low stripping efficiency, easiness in corrosion of a substrate, high resource recovery difficulty, poor process controllability, non-lasting copper protection of the traditional copper-protectin