A multi-metal composite electroplating process

Abstract

The present invention relates to a multi-metal composite electroplating process method, comprising the following steps: step S1: pre-treatment, removing oil and impurities on the surface of the material by chemical reagents, followed by activation treatment; step S2: copper plating, placing the pre-treated material in a copper cyanide plating solution, shocking with a current density of 50-80 amperes per square decimeter for 3-5 minutes, then reducing the current density to 25 amperes per square decimeter, and electroplating for 6-10 minutes. The multi-metal composite electroplating process method significantly improves the quality and consistency of multi-metal composite electroplating products, especially in terms of uniformity and stability of gold film thickness, reduces production cycle, improves the overall efficiency of the production line, and reduces unit energy consumption and raw material consumption.

Description

Technical Field

[0001] The present invention relates to the field of electroplating technology, and specifically to a multi-metal composite electroplating process method, which is mainly suitable for surface treatment scenarios of electronic components, precision instrument parts and other metal products that require high corrosion resistance, wear resistance and electrical conductivity. Background Art

[0002] Traditional single metal electroplating can no longer meet the needs of modern industry. Multi-metal composite electroplating shows great potential in improving product performance because it can combine the advantages of various metals. However, the technical difficulties in the multi-metal composite electroplating process mainly include how to ensure good bonding between the metal layers and how to avoid mutual contamination between different metals. These problems limit the widespread application and development of this technology.

[0003] Specific solutions of existing technologies: At present, the methods commonly adopted in the industry to address the problems existing in multi-metal composite electroplating include but are not limited to: (1) strict pre-treatment process, that is, to thoroughly remove oil and oxides on the surface of the substrate through acid washing, alkaline washing, etc., to enhance the adhesion of the subsequent coating; (2) application of intermediate transition layer, such as first plating a thin layer of nickel as a transition layer, and then plating the target metal, which can improve the interlayer bonding strength to a certain extent; (3) optimizing the electrolyte formula, by adjusting the proportion of solution components to reduce the interaction between different metals. Although these methods can alleviate the problem to a certain extent, they still have problems such as low efficiency and high cost.

[0004] Although the existing multi-metal composite electroplating technology has made some progress, it still faces many challenges in the actual production process, and the following problems still exist: (1) Due to the lack of effective surface pretreatment measures, the bonding strength between the coating and the base material is poor; (2) The traditional single process is difficult to take into account the differences in the properties of multiple metals, resulting in unstable quality of the final product; (3) Equipment aging and slow technological updates cannot adapt to rapidly changing market demands. Summary of the invention

[0005] 1. Technical problems solved In order to solve the above technical problems, the present invention provides a multi-metal composite electroplating process method.

[0006] (II) Technical solution Based on this, the present invention provides the following technical solution: a multi-metal composite electroplating process method, comprising the following steps: Step S1: Pretreatment, using chemical reagents to remove oil and impurities on the surface of the material to ensure that the substrate is clean, followed by activation treatment; Step S2: copper plating, placing the pre-treated material in a copper cyanide plating solution, shocking with a current density of 50-80 A / dm2 for 3-5 minutes, then reducing the current density to 25 A / dm2, electroplating for 6-10 minutes, to form a uniform and dense copper plating layer; Step S3: nickel plating, first electroplating semi-bright nickel, then electroplating high-phosphorus nickel alloy, to generate a nickel coating with good corrosion resistance and wear resistance; Step S4: intermediate cleaning, subjecting the nickel-plated material to ultrasonic degreasing treatment, and then washing and drying it with water to thoroughly remove the pollutants remaining on the surface and maintain cleanliness; Step S5: Tin plating, in a tin plating solution with a pH value of 3.8-4.5, at a temperature of 50-60°C and a current density of 2-6A / dm 2 Tin plating treatment is performed for 40-50 minutes, the tin plating concentration is 30-50g / L tin methanesulfonate, 10-20g / L methanesulfonic acid, 2-3mg / L sodium propargyl sulfonate as softener, 1-2mg / L sodium allyl sulfonate as moving agent, and 0.2g / L-10g / L water-soluble fiber as reinforcing agent, and the length is 2-4mm; Step S6: gold plating, placing the tinned material into a spot plating mold, first performing high-speed pre-gold plating, and then performing high-speed electro-gold plating, wherein the anode water spray device inside the spot plating mold is a double water spray port; Step S7: Sealing treatment: 80 mL / L of TL-2003 sealing agent is used for sealing, and an environmentally friendly diluent is used at a temperature of 55° C. for 5 seconds to seal the micropores on the surface of the material and enhance the anti-corrosion performance; Step S8: Drying is carried out in an oven at a temperature of 70-300° C. for 30-120 min to eliminate excess moisture and chemical residues on the material.

[0007] Preferably, the operation of removing oil and impurities on the surface of the material is as follows: ultrasonic degreasing, using an alkaline solution, the composition of which is: 2%-6% by mass of fatty acid methyl ester ethoxylate sulfonate, 15%-25% by mass of sodium hydroxide, and the rest is water, and the ultrasonic degreasing time is 3-5 minutes; electrolytic degreasing, using the plated piece as the anode and the stainless steel plate as the cathode, in a solution environment with a pH value of 8-14, passing direct current, and the current density is 5-15A / dm 2 The solution temperature is 60-80°C, and an alkaline solution is used, the ingredients are: 1%-5% by mass of fatty acid methyl ester ethoxylate sulfonate, 20%-30% by mass of sodium hydroxide, and the rest is water. The electrolytic degreasing time is 3-5 minutes.

[0008] Preferably, the specific operation of the activation treatment is: pickling activation uses a sulfuric acid solution with a mass fraction of 10%-20%, and immersion treatment at room temperature for 6-10 minutes for activation.

[0009] Preferably, the composition of the copper cyanide plating solution is: copper content 15-20 g / L; sodium cyanide (free) 7-13 g / L; potassium sodium tartrate 20-30 g / L; disodium EDTA 5-10 g / L.

[0010] Preferably, the semi-bright nickel electroplating is Ni 2+ , 80g / L; NiCl2.6H2O, 13g / L; H3BO3, 40g / L; RamTechNicka WA311 wetting agent, 15mL / L; RamTech Nicka BR311 brightener, 5mL / L; pH value 4.5; current density 10A / dm 2 , temperature 60℃, time 1min, thickness not less than 1μm; electroplating high phosphorus nickel alloy uses Ni 2+ , 110g / L; NiCl2.6H2O, 15g / L,; H3BO3, 20g / L; RamTech Nicka 1225SA additive, 15mL / L; RamTech Nicka 1225BR brightener, 11mL / L; RamTech Nicka 1225R2 additive, 30mL / L; pH 1.5; current density 10A / dm 2 ; Temperature 60℃; Time 1min; Thickness not less than 0.5μm.

[0011] Preferably, the ultrasonic degreasing treatment is specifically as follows: using an alkaline solution, the ingredients of which are 1-5% by mass of the sulfonate of the surfactant fatty acid methyl ester ethoxylate, 20-30% of sodium hydroxide, and the rest of water, and the ultrasonic degreasing time is 3-5 minutes.

[0012] Preferably, high-speed pre-gold plating uses Au + , 0.5g / L; MetGold (HS) aquarium salt, 1.5kg / L; MetGold (HS) aquarium organic additive, 5g / L; pH value 4.7, current density 10A / dm 2 , temperature 55℃, time 7.5s, thickness not less than 0.075μm.

[0013] Preferably, high-speed electroplating gold is Au + , 8g / L; MetGold (HS) aquarium salt, 1.5kg / L; MetGold (HS) aquarium cobalt brightener, 5g / L; MetGold (HS) aquarium organic additive, 5g / L; pH value 4.7, current density 10A / dm 2, temperature 55℃, time 23s, thickness not less than 0.381μm.

[0014] (III) Beneficial effects Compared with the prior art, the present invention provides a multi-metal composite electroplating process method, which has the following beneficial effects: This multi-metal composite electroplating process method significantly improves the quality and consistency of multi-metal composite electroplating products, especially in terms of the uniformity and stability of gold film thickness, shortens the production cycle, improves the overall efficiency of the production line, reduces unit energy consumption and raw material consumption, and upgrades the anode water nozzle device inside the spot plating mold to a double water nozzle, which improves the stability of the gold film thickness and prevents the risk of gold leakage when the nozzle is blocked by foreign matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a flow chart of the specific steps of the present invention; DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] See also Figure 1 , a multi-metal composite electroplating process method, comprising the following steps: step S1: first check whether all equipment are operating normally, and start the electroplating procedure only after confirming that they are correct, pre-treatment, remove oil and impurities on the surface of the material by chemical reagents to ensure that the substrate is clean, and then perform activation treatment; step S2: copper plating, place the pre-treated material in a copper cyanide plating solution, use a current of 50-80 A / dm2 for 3-5 minutes, then reduce the current density to 25 A / dm2, electroplate for 6-10 minutes, and form a uniform and dense copper plating layer; step S3: nickel plating, first electroplate semi-bright nickel, then electroplate high-phosphorus nickel alloy, to generate a nickel plating layer with good corrosion resistance and wear resistance; step S4: intermediate cleaning, ultrasonic degreasing treatment of the material after nickel plating, then water washing and drying, thoroughly remove the pollutants remaining on the surface, and maintain cleanliness; step S5: tin plating, in a tin plating solution with a pH value of 3.8-4.5, the temperature is 50-60°C and the current density is 2-6A / dm 2Tin plating is performed for 40-50 minutes, and the tin plating concentration is 30-50g / L of tin methanesulfonate, 10-20g / L of methanesulfonic acid, 2-3mg / L of softener sodium propargyl sulfonate, 1-2mg / L of displacement agent sodium allyl sulfonate, and reinforcing agent water-soluble fiber, with a content of 0.2g / L-10g / L and a length of 2-4mm; Step S6: Gold plating, placing the tinned material into a spot plating mold, first performing high-speed pre-gold plating, and then performing high-speed electroplating of gold, and the anode water nozzle device inside the spot plating mold is a double water nozzle; Step S7: Sealing treatment, sealing the holes with TL-2003 sealing agent 80mL / L, using an environmentally friendly diluent, a temperature of 55°C, a time of 5s, sealing the micropores on the surface of the material, and enhancing the anti-corrosion performance; Step S8: Drying, which is performed in an oven at a temperature of 70-300°C for 30-120min to eliminate excess moisture and chemical residues on the material.

[0018] In some embodiments, the operations for removing oil and impurities from the surface of the material are as follows: ultrasonic degreasing, using an alkaline solution, the ingredients of which are: 2%-6% by mass of fatty acid methyl ester ethoxylate sulfonate, 15%-25% by mass of sodium hydroxide, and the rest is water, and the ultrasonic degreasing time is 3-5 minutes; electrolytic degreasing, using the workpiece to be plated as the anode and the stainless steel plate as the cathode, in a solution environment with a pH value of 8-14, passing direct current with a current density of 5-15A / dm 2 The solution temperature is 60-80℃, and an alkaline solution is used. The ingredients are: 1%-5% fatty acid methyl ester ethoxylate sulfonate by mass, 20%-30% sodium hydroxide by mass, and the rest is water. The electrolytic degreasing time is 3-5min. The specific operation of the activation treatment is: acid pickling activation uses a 10%-20% sulfuric acid solution by mass, and the activation is carried out by soaking at room temperature for 6-10min. Fatty acid methyl ester ethoxylate sulfonate FMES has both anionic / non-ionic properties and is an anionic-non-amphoteric surfactant. Among anionic surfactants, it is the product with the highest cleaning ability.

[0019] In some embodiments, the composition of the copper cyanide plating solution is: copper content 15-20 g / L; sodium cyanide (free) 7-13 g / L; potassium sodium tartrate 20-30 g / L; disodium EDTA 5-10 g / L, sodium cyanide (free) refers to sodium cyanide that is not combined with other substances, its chemical formula is NaCN, it is a white crystalline powder, it is easily deliquescent, has a faint smell of bitter almonds, and is highly toxic. Free sodium cyanide is easily soluble in water and easily hydrolyzed to generate hydrogen cyanide. The aqueous solution is strongly alkaline. Sodium potassium tartrate is also called potassium sodium tartrate, Roche salt, and Rochelle salt. It is a complex salt formed by sodium tartrate and potassium tartrate. Disodium EDTA can be used as a stabilizer, coagulant, antioxidant and preservative. It can protect color, resist oxidation, and prevent corrosion synergistically and stabilize. Its complexation can prevent harmful reactions such as discoloration, deterioration, turbidity and oxidation loss of vitamin C caused by metal ions. It can quickly perform copper plating operations on the surface of the substrate, and the formed coating will not bubble, peel, or produce defects such as black stripes and black spots.

[0020] In some embodiments, the semi-bright nickel electroplating is Ni 2+ , 80g / L; NiCl2.6H2O, 13g / L; H3BO3, 40g / L; RamTech Nicka WA311 wetting agent, 15mL / L; RamTech Nicka BR311 brightener, 5mL / L; pH value 4.5; current density 10A / dm 2 , temperature 60℃, time 1min, thickness not less than 1μm, semi-bright nickel coating contains sulfur, which can concentrate corrosion on the semi-bright nickel coating; taking WA311 wetting agent volume fraction, BR311 brightener volume fraction, current density and electroplating time as factors, the semi-bright nickel electroplating process was optimized through DOE of Minitab software, and a partial factorial scheme of four factors, three levels, three center points and one experiment was adopted. A total of 19 experiments were carried out, and the results are shown in Tables 1 and 2.

[0021] Table 1 Orthogonal test scheme and results of semi-bright nickel electroplating Table 2 Variance analysis of orthogonal test for electroplating ordinary semi-bright nickel From Table 1 and Table 2, we can see that the four first-order factors and the interaction of one second-order factor are all significant, and the P values ​​for bending and lack of fit are > 0.05, indicating that the model is effective and has a good linear relationship. The optimal combination is: WA311 wetting agent 15mL / L, BR311 brightener 5mL / L, current density 10A / dm 2, electroplating time 0.665min. The coatings obtained in the three tests (4, 8 and 12) under the optimal conditions were semi-bright, with an average thickness of 1.06μm, which was within the 95% confidence interval (1.024, 1.071), indicating that the test results were normal and highly reliable.

[0022] Electroplating high phosphorus nickel alloy uses Ni 2+ , 110g / L; NiCl2.6H2O, 15g / L,; H3BO3, 20g / L; RamTechNicka 1225SA additive, 15mL / L; RamTech Nicka 1225BR brightener, 11mL / L; RamTech Nicka1225R2 additive, 30mL / L; pH value 1.5; current density 10A / dm 2 ; Temperature 60℃; Time 1min; Thickness not less than 0.5μm, the high-phosphorus nickel alloy coating is finely crystallized, bright and smooth, and has good corrosion resistance. The standard potential of the high nickel-phosphorus alloy coating is more positive than that of the nickel coating. When corrosion occurs from the pores of the nickel-phosphorus alloy, the nickel coating is the anode relative to the nickel-phosphorus alloy coating. Affected by the lateral galvanic cell effect, corrosion mainly occurs in the nickel coating, and the electrochemical corrosion reaction directed to the copper substrate is delayed. In addition, since the standard potentials of the nickel-phosphorus alloy and nickel are close, when there are pores in the coating and a corrosion cell is formed, the nickel coating is little affected by the electrochemical corrosion of the galvanic cell, so the nickel coating can protect the copper substrate from electrochemical corrosion for a long time.

[0023] In this application, RamTech Nicka WA311 wetting agent, RamTech Nicka BR311 brightener, RamTech Nicka 1225SA additive, RamTech Nicka 1225BR brightener, and RamTech Nicka 1225R2 additive are all from Yongbao Technology Company.

[0024] Minitab software DOE was used to optimize the electroplating process of high-phosphorus nickel. A partial factorial scheme with five factors, three levels, three center points, and one test was used, and a total of 19 tests were conducted. As shown in Tables 3 and 4, the five first-order factors and one second-order factor interaction were significant, and the P values ​​for bending and lack of fit were > 0.05, indicating that the model was effective and had a good linear relationship. The optimal parameter combination was: 1225SA additive volume fraction 15 mL / L, 1225BR brightener volume fraction 11.5 mL / L, 1225R2 additive volume fraction 30.0 mL / L, current density 10 A / dm 2, electroplating time 0.585min. The coatings obtained in the three tests (7, 14 and 16) under the optimal conditions have bright appearance, P mass fraction within the required range, and average thickness of 0.508μm, within the 95% confidence interval (0.501, 0.512), indicating that the test results are normal and have high credibility.

[0025] Table 3 Orthogonal test scheme and results of electroplating high phosphorus nickel Table 4 Variance analysis of orthogonal test for high phosphorus nickel electroplating In some embodiments, the ultrasonic degreasing treatment is specifically as follows: using an alkaline solution, the ingredients of which are 1-5% by mass of the sulfonate of the surfactant fatty acid methyl ester ethoxylate, 20-30% sodium hydroxide, and the rest is water, and the ultrasonic degreasing time is 3-5 minutes.

[0026] In some embodiments, high-speed pre-gold plating uses Au + , 0.5g / L; MetGold (HS) aquarium salt, 1.5kg / L; MetGold (HS) aquarium organic additive, 5g / L; pH value 4.7, current density 10A / dm 2 , temperature 55℃, time 7.5s, thickness not less than 0.075μm, high-speed electroplating gold using Au + , 8g / L; MetGold (HS) aquarium salt, 1.5kg / L; MetGold (HS) aquarium cobalt brightener, 5g / L; MetGold (HS) aquarium organic additive, 5g / L; pH value 4.7, current density 10A / dm 2 , temperature 55℃, time 23s, thickness not less than 0.381μm, MetGold (HS) opening salt, MetGold (HS) opening organic additives, MetGold (HS) opening cobalt brightener are all from Suzhou Metalor Company. The spot plating mold design is optimized, and a double water nozzle system is introduced to increase the stability of the gold film thickness and anti-clogging performance, thereby significantly improving product quality and reliability.

[0027] Taking the mass concentration of organic additives in MetGold (HS) tank, the mass concentration of cobalt brightener in MetGold (HS) tank, current density, electroplating time as factors, and whether it is double water spraying or single water spraying for spot plating mold, the DOE of Minitab software was used to optimize the electroplating gold process. A partial factorial scheme with four factors and three levels plus three center points and one experiment was adopted. A total of 19 experiments were carried out. The results are shown in Tables 5 and 6.

[0028] Table 5 Orthogonal test scheme and results of electroplating gold Table 6 Analysis of variance of orthogonal test of electroplating gold source Degrees of Freedom Standard Deviation Mean square error F P Main Effect 2 2.89460 1.44730 28018.70 0.000 Linear 1 0.006997 0.006997 86.33 0.000 Two-factor interaction 1 0.45563 0.45563 8820.58 0.000 error 14 0.0072 0.0072 \ \ bending 1 0.002586 0.002586 500.56 0.633 Lack of Fit 2 0.0009110 0.000911 240.98 0.299 Pure Error 14 0.00004 0.000003 \ \ From Table 10 and Table 11, it can be seen that the four first-order factors and the interaction of one second-order factor are all significant, and the P values ​​corresponding to bending and lack of fit are > 0.05, indicating that the model is effective and has a good linear relationship. The optimal parameter combination is: MetGold (HS) organic additive mass concentration 0.5g / L, MetGold (HS) cobalt brightener mass concentration 0.95g / L, current density 25A / dm 2 , electroplating time 0.1639min, with dual water spraying device for plating mold. Under this condition, three tests (8, 9 and 14) all obtained gold layers with good appearance, qualified gold layer thickness and nitric acid corrosion resistance, with an average thickness of 0.447μm, within the 95% confidence interval (0.43743, 0.45523), indicating that the test results are normal and highly reliable.

[0029] To summarize, this technology mainly solves the following technical problems: the anode water nozzle device inside the spot plating mold is upgraded to a double water nozzle, which improves the stability of the gold film thickness and prevents the risk of gold leakage when the nozzle is blocked by foreign objects, thereby achieving efficient and stable copper plating-nickel plating-tin plating-gold plating continuous operation, improving the overall efficiency of the production line, and reducing unit energy consumption and raw material consumption.

[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A multi-metal composite electroplating process, characterized in that: The following steps are involved: Step S1: Pretreatment, using chemical reagents to remove oil and impurities on the surface of the material, followed by activation treatment; Step S2: copper plating, placing the pre-treated material in a copper cyanide plating solution, shocking with a current density of 50-80 A / dm2 for 3-5 minutes, then reducing the current density to 25 A / dm2, and electroplating for 6-10 minutes; Step S3: nickel plating, first electroplating semi-bright nickel, then electroplating high-phosphorus nickel alloy; Step S4: intermediate cleaning, subjecting the nickel-plated material to ultrasonic degreasing treatment, followed by water washing and air drying; Step S5: Tin plating, in a tin plating solution with a pH value of 3.8-4.5, at a temperature of 50-60°C and a current density of 2-6A / dm 2 Tin plating treatment is performed for 40-50 minutes, the tin plating concentration is 30-50g / L tin methanesulfonate, 10-20g / L methanesulfonic acid, 2-3mg / L sodium propargyl sulfonate as softener, 1-2mg / L sodium allyl sulfonate as moving agent, and 0.2g / L-10g / L water-soluble fiber as reinforcing agent, and the length is 2-4mm; Step S6: gold plating, placing the tinned material into a spot plating mold, first performing high-speed pre-gold plating, and then performing high-speed electro-gold plating, wherein the anode water spray device inside the spot plating mold is a double water spray port; Step S7: Sealing treatment: 80 mL / L of TL-2003 sealing agent, environmentally friendly diluent, temperature 55°C, time 5s; Step S8: Drying is carried out in an oven at a temperature of 70-300° C. for 30-120 min to eliminate excess moisture and chemical residues on the material.

2. A multi-metal composite electroplating process according to claim 1, characterized in that: The operation of removing oil and impurities on the surface of the material in step S1 is as follows: Ultrasonic degreasing uses an alkaline solution with the following ingredients: 2%-6% by mass of fatty acid methyl ester ethoxylate sulfonate, 15%-25% by mass of sodium hydroxide, and the rest is water. The ultrasonic degreasing time is 3-5 minutes. Electrolytic degreasing, with the plated piece as the anode and the stainless steel plate as the cathode, in a solution environment with a pH value of 8-14, with direct current and a current density of 5-15A / dm 2 The solution temperature is 60-80°C, and an alkaline solution is used, the ingredients are: 1%-5% by mass of fatty acid methyl ester ethoxylate sulfonate, 20%-30% by mass of sodium hydroxide, and the rest is water. The electrolytic degreasing time is 3-5 minutes.

3. A multi-metal composite electroplating process according to claim 1, characterized in that: The specific operation of the activation treatment in step S1 is: pickling activation uses a sulfuric acid solution with a mass fraction of 10%-20%, and immersion treatment at room temperature for 6-10 minutes for activation.

4. The multi-metal composite electroplating process according to claim 1, characterized in that: In step S2, the composition of the copper cyanide plating solution is: copper content 15-20 g / L; sodium cyanide (free) 7-13 g / L; potassium sodium tartrate 20-30 g / L; disodium EDTA 5-10 g / L.

5. The multi-metal composite electroplating process according to claim 1, characterized in that: In step S3, the semi-bright nickel electroplating is carried out using Ni 2+ , 80g / L; NiCl2ꞏ6H2O, 13g / L; H3BO3, 40g / L; RamTech Nicka WA311 wetting agent, 15mL / L; RamTech Nicka BR311 brightener, 5mL / L; pH value 4.5; current density 10A / dm 2 , temperature 60°C, time 1min, thickness not less than 1μm; Electroplating high phosphorus nickel alloy uses Ni 2+ , 110g / L; NiCl2ꞏ6H2O, 15g / L,; H3BO3, 20g / L; RamTech Nicka1225SA additive, 15 mL / L; RamTech Nicka 1225BR brightener, 11 mL / L; RamTech Nicka 1225R2 additive, 30 mL / L; pH 1.5; current density 10A / dm 2 ; Temperature 60°C; Time 1min; Thickness not less than 0.5μm.

6. The multi-metal composite electroplating process according to claim 1, characterized in that: In step S4, the ultrasonic degreasing treatment is specifically as follows: using an alkaline solution, the components of which are 1-5% by mass of sulfonate of surfactant fatty acid methyl ester ethoxylate, 20-30% of sodium hydroxide, and the rest of water, and the ultrasonic degreasing time is 3-5 minutes.

7. The multi-metal composite electroplating process according to claim 1, characterized in that: In step S6, high-speed pre-gold plating is performed using Au + , 0.5g / L; MetGold (HS) aquarium salt, 1.5kg / L; MetGold (HS) aquarium organic additive, 5g / L; pH value 4.7, current density 10A / dm 2 , temperature 55°C, time 7.5s, thickness not less than 0.075μm.

8. The multi-metal composite electroplating process according to claim 1, characterized in that: In step S6, high-speed electroplating of Au + , 8 g / L; MetGold (HS) aquarium salt, 1.5 kg / L; MetGold (HS) aquarium cobalt brightener, 5 g / L; MetGold (HS) aquarium organic additive, 5 g / L; pH value 4.7, current density 10 A / dm 2 , temperature 55°C, time 23s, thickness not less than 0.381μm.

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