Non-toxic sodium cyanide or potassium cyanide silver-plating electroplating solution and preparation method therefor

Description

Non-poisonous sodium cyanide or potassium cyanide silver plating solution and preparation method thereof TECHNICAL FIELD

[0001] The present application relates to a non-poisonous sodium cyanide or potassium cyanide silver plating solution and a preparation method thereof, and belongs to the technical field of plating solutions and preparation thereof. BACKGROUND

[0002] The complexing agent is a compound capable of forming a complex ion with a metal ion. In an electroplating solution, except for a few electroplating solutions such as acid solution plating iron, plating nickel, plating chromium, and plating copper, which do not use or do not need to use a complexing agent, most electroplating solutions such as alkaline solution plating silver, plating gold, plating copper, plating zinc, plating tin, and plating copper-tin alloy all need to use a complexing agent.

[0003] Silver has a wide range of uses in industry and daily life, is a high-tech metal, and is also a dual-purpose metal for military and civilian use. The electroplated silver layer has a unique silver-white luster and stable chemical properties. The electroplated silver layer has high electrical conductivity and thermal conductivity, and has good soldering performance. Electroplated silver has been widely used in printed circuit boards and electronic components in the electronic industry, important parts of instruments and meters, aircraft, optical instruments, and high-frequency components and waveguide communication equipment and devices to ensure good electrical conductivity and soldering performance. In addition, electroplated silver has a beautiful silver-white luster and is widely used as a decorative layer in household appliances, tableware, and various handicrafts.

[0004] As of now, the main non-cyanide silver plating systems that have been studied include sulfite silver plating, thiosulfate silver plating, iodide silver plating, ammonium imino disulfonate (NS) silver plating, imidazole-sulfosalicylic acid silver plating, succinimide silver plating, hydantoin silver plating, and nicotinic acid silver plating. However, the non-poisonous sodium cyanide or potassium cyanide systems currently in use generally have problems such as poor plating solution stability, low plating layer performance, and harsh allowable process conditions (narrow current density range). Therefore, it is urgent to develop a complexing agent to replace cyanide for use in non-cyanide electroplating processes.

[0005] The present application relates to a non-poisonous sodium cyanide or potassium cyanide silver plating solution and preparation method thereof, and belongs to the technical field of plating solutions and preparation thereof. 26～27, far superior to the cyanide-free complexing agent in the prior art, the plating solution prepared from the complexing agent has stable quality, good dispersibility, a wider range of process current density that can be used, and a wide range of application of the plating solution. With higher requirements for the quality of electroplated products, after meeting the higher complexing force, the deep plating capacity of the complexing agent also needs to be considered, the plating layer needs to be more compact, and the electroplating efficiency needs to be improved to achieve energy saving of the electroplating process. Based on the problems to be solved by the newly proposed cyanide-free electroplating, the inventors of the present application have developed a new non-toxic sodium cyanide or potassium cyanide silver plating solution and disclosed a preparation method thereof. SUMMARY

[0006] One of the purposes of the present application is to solve the defects of the prior art and provide a new non-toxic sodium cyanide or potassium cyanide silver plating solution. The plating solution has strong deep plating capacity, the plating layer is more delicate and compact, the electroplating efficiency is high, and energy saving of the electroplating process can be achieved.

[0007] The second purpose of the present application is to provide a new preparation method of the non-toxic sodium cyanide or potassium cyanide silver plating solution. The method is easy to realize industrial production, and the quality of the produced plating solution product is stable.

[0008] The technical scheme adopted by the present application to solve the technical problems is:

[0009] A non-toxic sodium cyanide or potassium cyanide silver plating solution, wherein the general formula of the complexing agent silver salt in the non-toxic sodium cyanide or potassium cyanide silver plating solution is Ag n [C 4n N 4n+2 S 2n O 2n H 2n+6 , and the structural formula is as follows:

[0010] Wherein, n is 1, 2, 3, …, 50.

[0011] Preferably, the general formula of the complexing agent in the non-toxic sodium cyanide or potassium cyanide silver plating solution is Rm[C 2m N 2m+1 S m O m H m+3 , and the structural formula is as follows:

[0012] Wherein, R is K or Na, and m is 1, 2, 3, …, 50.

[0013] The foregoing technical scheme is explained below with several examples:

[0014] A: When R is K and m is 1, the general formula of the complexing agent is K[C2N3SOH4], and the structural formula is as follows:

[0015] The structure of the complexing agent silver salt obtained by processing the complexing agent is Ag[C2N3SOH4], n=m, and the structure is as follows:

[0016] B: when R is K and n is 20, the structure of the complexing agent is as follows:

[0017] The structure of the complexing agent silver salt obtained by processing the complexing agent is as follows:

[0018] C: when R is Na and n is 50, the general formula of the complexing agent is Na 50 [C 100 N 101 S 50 O 50 H 53 ], and the structure is as follows:

[0019] The structure of the complexing agent silver salt obtained by processing the complexing agent is as follows:

[0020] Preferably, R is K, n is 1, 2, or 3, and the structures are as follows, respectively:

[0021] Preferably, in the non-toxic cyanide sodium or potassium silver plating solution, the mass fraction of the complexing agent is 10-30%, the mass fraction of the complexing agent silver salt is 0.8-2.0%, and the balance is water.

[0022] More preferably, in the non-toxic cyanide sodium or potassium silver plating solution, the mass fraction of the complexing agent is 20%, the mass fraction of the complexing agent silver salt is 1.5%, and the balance is water.

[0023] In the non-toxic cyanide sodium or potassium silver plating solution of the present application, the complexing agent silver salt is prepared by reacting the complexing agent of the present application with a soluble silver salt, and the complexing agent in the preparation of the plating solution can be selected from conventional complexing agents, the complexing agent of the present application, or preferably the complexing agent of the present application. The value of m in the complexing agent silver salt can be the same as the value of n in the complexing agent, or it can be different. For example, the complexing agent in the aforementioned A can be mixed with the complexing agent silver salt in the aforementioned A, or the complexing agent silver salt in the aforementioned B, to process the non-toxic cyanide sodium or potassium silver plating solution of the present application.

[0024] Preferably, the complexing agent is prepared from potassium ferrocyanide, sodium or potassium thiosulfate (potassium thiosulfate is used when R is K, and sodium thiosulfate is used when R is Na) and urea, in the presence of oxygen, with rhodium and / or platinum as catalyst, through solid-state polymineral salt reaction, dissolution in water, separation, concentration of the separated liquid and drying.

[0025] The reaction equation of the complexing agent preparation method of the present application is as follows: (n / 4)[K4Fe(CN)6]+nNa2S2O3+nCH4N2O+20 / nO2=K n [C 2n N 2n+1 S n O n H n+3 ]+(n / 12)Fe3C+(5n / 12)C+(n / 4)N2+nNa2SO3+(n-1)NH3,

[0026] or; (n / 4)[K4Fe(CN)6]+nK2S2O3+nCH4N2O+20 / nO2=K n [C 2n N 2n+1 S n O n H n+3 ]+(n / 12)Fe3C+(5n / 12)C+(n / 4)N2+nK2SO3+(n-1)NH3;

[0027] The present application also discloses a specific preparation method of the complexing agent, which comprises the following steps:

[0028] Potassium ferrocyanide, sodium or potassium thiosulfate and urea are placed in a rotary kiln, and rhodium and / or platinum is added as catalyst, and the reaction is carried out at 450-650℃ for 5-7 hours; the polymineral salt is dissolved in water, and the insoluble substances are removed to obtain a separated liquid, which is dried to obtain the finished complexing agent.

[0029] Preferably, the separation is carried out by any one or several of suction filtration, plate-frame pressure filtration and centrifugal separation.

[0030] Preferably, the separated liquid is concentrated before drying, and the separated liquid is concentrated to a water content of 30-40%, and the concentrated material is dried to a water content of less than 5%, and the concentration is carried out by vacuum concentration.

[0031] Preferably, the drying is carried out by spray drying, and the inlet air temperature of the spray drying is 100-200℃.

[0032] The preparation method of the complexing agent silver salt is as follows: water is added into a reactor, and a soluble silver salt and a complexing agent are added into a reaction device, and then the reaction is stirred at normal temperature and pressure, after the reaction is completed, the precipitate is separated, rinsed and dried to obtain the complexing agent silver salt.

[0033] The preparation method of the non-poisonous sodium cyanide or potassium cyanide silver plating solution of the present application is as follows: a complexing agent silver salt, a complexing agent and water are mixed according to the proportion, stirred and dissolved, and then the pH value is adjusted to 10.0-11.5 to obtain the non-poisonous sodium cyanide or potassium cyanide silver plating solution.

[0034] The present application has the following advantages:

[0035] The raw material of the complexing agent of the present application is widely available, low in price, simple in preparation process, transportation, storage and use, and low in production cost; the complexing agent of the present application is applied to the production of plating solution, convenient to process, and the prepared plating solution has strong complexing ability to metal, for example, the complexing constant of the complexing agent of the present application to copper ion can reach 10 26-27 (comparable to the existing non-cyanide complexing agent), much better than the conventional complexing agent (mainly potassium pyrophosphate, citric acid and HEDP) in the prior art), the plating solution prepared from the complexing agent of the present application is stable in quality, has good dispersibility, a wide range of process current density can be used, and has a wide application range (such properties are comparable to the plating solution prepared from the existing non-cyanide complexing agent), in addition, the plating solution has strong deep plating ability, the plated layer is more delicate and dense, the plating efficiency is high, and energy saving of the plating process can be realized. DETAILED DESCRIPTION

[0036] The technical solutions of the present application are further described below through specific examples. The reagents, raw materials and devices and facilities used in the following examples are all commercially available conventional reagents, raw materials, devices and facilities.

[0037] Example 1:

[0038] A complexing agent, the structural formula of which is as follows:

[0039] The reaction formula of the polymineral salt of the complexing agent is as follows:

[0040] (1 / 4)[K4Fe(CN)6]+K2S2O3+CH4N2O+20O2=K[C2N3SOH4]+(1 / 12)Fe3C+(5 / 12)C+(1 / 4)N2+K2SO3; the preparation method steps are as follows:

[0041] The yellow prussiate, sodium or potassium thiosulfate and urea are placed in a rotary reaction kiln, which is fixed with catalyst rhodium and / or platinum, and reacted for 7 hours at 450-460℃ in an oxygen-containing atmosphere; the polymerized polymineral salt is dissolved in water, separated, and the insoluble matter is removed to obtain a separated liquid, which is dried to obtain the finished complexing agent.

[0042] In Example 1, the separation is performed by suction filtration, and the separated liquid is concentrated before drying, and the separated liquid is concentrated to a water content of 30%, and the concentrated material is dried to a water content of less than 5%, the concentration is performed by vacuum concentration, and the drying is performed by spray drying, and the inlet air temperature of the spray drying is 100-110℃.

[0043] Example 2

[0044] A complexing agent, the structural formula of which is as follows:

[0045] The polymineral salt reaction formula of the complexing agent is as follows:

[0046] (1 / 2)[K4Fe(CN)6]+2K2S2O3+2CH4N2O+10O2=K2[C4N5S2O2H5]+(1 / 6)Fe3C+(5 / 6)C+(1 / 2)N2+2K2SO3+NH3; the preparation method steps are as follows:

[0047] The yellow prussiate, sodium or potassium thiosulfate and urea are placed in a rotary reaction kiln, which is fixed with catalyst rhodium and / or platinum, and reacted for 5 hours at 640-650℃ in an oxygen-containing atmosphere; the polymerized polymineral salt is dissolved in water, separated, and the insoluble matter is removed to obtain a separated liquid, which is dried to obtain the finished complexing agent.

[0048] In Example 1, the separation is performed by plate and frame pressure filtration, and the separated liquid is concentrated before drying, and the separated liquid is concentrated to a water content of 40%, and the concentrated material is dried to a water content of less than 5%, the concentration is performed by vacuum concentration, and the drying is performed by spray drying, and the inlet air temperature of the spray drying is 190-200℃.

[0049] Example 3

[0050] A complexing agent, the structural formula of which is as follows:

[0051] The polymineral salt reaction formula of the complexing agent is as follows: (3 / 4)[K4Fe(CN)6]+3K2S2O3+3CH4N2O+20 / 3O2=K3[C6N7S3O3H6]+(1 / 4)Fe3C+(5 / 4)C+(3 / 4)N2+3K2SO3+2NH3; the preparation method steps are as follows:

[0052] The yellow prussiate, sodium or potassium thiosulfate and urea are placed in a rotary reaction kiln, in which rhodium and / or platinum catalysts are fixed, and reacted for 6 hours at 590-600℃ in an oxygen-containing atmosphere; the polymerized polymineral salt is dissolved in water, separated, and the insoluble matter is removed to obtain a separation liquid, which is dried to obtain the complexing agent product.

[0053] In Example 3, the separation is performed by centrifugal separation, and the separation liquid is concentrated before drying, and the separation liquid is concentrated to a water content of 35%, and the concentrated material is dried to a water content of less than 5%, the concentration is performed by vacuum concentration, and the drying is performed by spray drying, and the inlet air temperature of the spray drying is 160-170℃.

[0054] Example 4

[0055] A complexing agent, the structural formula and preparation method of which are the same as those of Example 3, except that n=50.

[0056] Example 5

[0057] A complexing agent, the structural formula and preparation method of which are the same as those of Example 1, except that Na is used instead of K.

[0058] Example 6

[0059] A complexing agent, the structural formula and preparation method of which are the same as those of Example 2, except that Na is used instead of K.

[0060] Example 7

[0061] A complexing agent, the structural formula and preparation method of which are the same as those of Example 3, except that Na is used instead of K.

[0062] Example 8

[0063] A complexing agent, the structural formula and preparation method of which are the same as those of Example 4, except that Na is used instead of K.

[0064] The complexing agents of Examples 1-8 of the present application are used for electroplating, and the use amount of the complexing agent in the electroplating solution for pre-plating silver is 1-40%, preferably 20%. The use of the complexing agent of the present application is illustrated by taking the use amount of 20% as an example.

[0065] The reaction formula for preparing the silver salt of the complexing agent from the complexing agent is as follows:

[0066] AgNO3+K[C2N3SOH4]=KNO3+Ag[C2N3SOH4]. The reaction condition is normal temperature and pressure.

[0067] Example 9: Electroplating solution for pre-plating silver using the complexing agent of Example 1

[0068] To a reaction vessel was added water, the complexing agent of Example 1 was added in a molar ratio, and a molar amount of silver salt solution (silver nitrate solution) was added to react. After the reaction was completed, the precipitate was rinsed and dried to obtain a complexing agent silver salt;

[0069] The electroplating solution was prepared by mixing 20% of the complexing agent, 2.0% of the complexing agent silver salt, and the balance of water, and adjusting the pH to 10.0 using sodium hydroxide.

[0070] Example 10: Electroplating solution for pre-plating silver using the complexing agent of Example 2

[0071] To a reaction vessel was added water, the complexing agent of Example 2 was added in a molar ratio, and a molar amount of silver salt solution (silver nitrate solution) was added to react. After the reaction was completed, the precipitate was rinsed and dried to obtain a complexing agent silver salt;

[0072] The electroplating solution was prepared by mixing 20% of the complexing agent, 2.0% of the complexing agent silver salt, and the balance of water, and adjusting the pH to 11.0 using sodium hydroxide.

[0073] Example 11: Electroplating solution for pre-plating silver using the complexing agent of Example 3

[0074] To a reaction vessel was added water, the complexing agent of Example 3 was added in a molar ratio, and a molar amount of silver salt solution (silver nitrate solution) was added to react. After the reaction was completed, the precipitate was rinsed and dried to obtain a complexing agent silver salt;

[0075] The electroplating solution was prepared by mixing 20% of the complexing agent, 2.0% of the complexing agent silver salt, and the balance of water, and adjusting the pH to 11.5 using sodium hydroxide.

[0076] Examples 12-16: Electroplating solution for pre-plating silver using the complexing agents of Examples 4-8, respectively

[0077] To a reaction vessel was added water, the complexing agents of Examples 4-8 were added in a molar ratio, and a molar amount of silver salt solution (silver nitrate solution) was added to react. After the reaction was completed, the precipitate was rinsed and dried to obtain a complexing agent silver salt;

[0078] The electroplating solution was prepared by mixing 20% of the complexing agent, 2.0% of the complexing agent silver salt, and the balance of water, and adjusting the pH to 11.0 using sodium hydroxide.

[0079] Comparative Example 17: Potassium pyrophosphate complexing agent

[0080] The plating solution was prepared by mixing 20% of the complexing agent, 2.0% of the silver salt of pyrophosphoric acid, and the rest of water, and adjusting the pH to 11.0 with sodium hydroxide.

[0081] Comparative Example 18: Complexing agent of Patent No. 2014100151872

[0082] The plating solution was prepared by mixing 20% of the complexing agent, 2.0% of the silver salt of pyrophosphoric acid, and the rest of water, and adjusting the pH to 11.0 with sodium hydroxide.

[0083] Performance test:

[0084] The above Examples 9-16 and Comparative Examples 17-18 were subjected to performance tests according to the following methods.

[0085] The cyanide-free pre-plating silver plating solutions prepared from Examples 9-16 and Comparative Examples 17-18 were subjected to the following studies:

[0086] 1. Hull cell test (267 ml)

[0087] 1.1 Preliminary test: The cyanide-free pre-plating silver plating solutions prepared from Examples 9-16 and Comparative Examples 17-18 were subjected to sheet plating under the conditions of temperature 25°C, circuit 1A (constant current), air agitation, and time 5 min. During the sheet plating of the plating solutions of Examples 9-16, it was observed that the cell voltage was relatively stable under the constant current condition, and the plated sheets showed the characteristics of semi-spot, fine crystals on a large area. Examples 9-16 were all superior to Comparative Example 18, and Comparative Example 18 was superior to Comparative Example 17.

[0088] 1.2 Hull cell test to determine the current density range:

[0089] The cyanide-free pre-plating silver plating solutions prepared from Examples 9-16 and Comparative Examples 17-18 were subjected to sheet plating by Hull to determine the optimal current density range under the conditions of temperature 55°C, current 1A, and time 10 min. The sheet material selected for sheet plating was A3 steel sheet of 0.5*70*100, which was polished with 600# water sandpaper. The current density of each point of the test sheet was calculated according to the empirical formula Jk = I (5.1-5.24LgL). Through sheet plating and current density calculation, it was found that the current density range of the plating solution prepared from Examples 9-16 was 0.5 A / dm 2 to 5 A / dm 2 .

[0090] 2. Test of plating solution and plating performance

[0091] 2.1 Measurement of current efficiency: The current efficiency of the plating solution prepared from Examples 9-16 was 94.6% on average, the current efficiency of the plating solution prepared from Example 17 was 89.8%, and the current efficiency of the plating solution prepared from Example 18 was 92.8%.

[0092] 2.2 Dispersion ability of plating solution

[0093] The dispersion ability of the plating solution was measured by the bending cathode method, with a current of 1 A, air agitation without oil, a temperature of 55°C, a time of 30 min, and a test material of 0.5*70*100 A3 copper sheet polished with 600# water sandpaper.

[0094] The average dispersion ability of the plating solution of Examples 9-16 was measured to be 94.5%, the dispersion ability of the plating solution of Example 17 was 90.1%, and the dispersion ability of the plating solution of Example 18 was 92.1%.

[0095] 2.3 Measurement of covering ability

[0096] The covering ability of the plating solution was measured by the inner hole method, with a copper pipe size of 10mm*100mm, a through hole and blind hole method, a plating solution temperature of 55°C, a cathode current density of 0.5A / dm 2 , and a time of 5 min. After the experiment, the iron pipe was cut open and the pipe coating was observed.

[0097] The cyanide-free pre-plated silver plating solution prepared from Examples 9-16 and Comparative Examples 17-18 was used as the experimental plating solution, and after the experiment, it was found that the through hole and blind hole were all plated with copper layer, indicating that the covering ability of the plating solution prepared from Examples 9-16 was excellent, better than Example 18, and much better than Example 17.

[0098] 2.4 Bonding force test

[0099] 2.4.1 Bending experiment: polished iron sheet (A3) with a thickness of 0.5mm was used, the temperature of the plating solution was 55°C, the cathode current density was 2A / dm 2 , and the time was 15 min.

[0100] The cyanide-free pre-plated silver plating solution prepared from Examples 9-16 and Comparative Examples 17-18 was used as the experimental plating solution, and after the experiment, the plated test piece was repeatedly bent until it broke, and there was no peeling phenomenon at the crack, proving that the coating and the substrate were not separated.

[0101] 2.4.2 Thermal shock experiment: polished iron sheet (A3) with a thickness of 0.5mm was used, the temperature of the plating solution was 55°C, the cathode current density was 2A / dm 2 , and the time was 15 min.

[0102] The cyanide-free pre-plated silver plating solution prepared from Examples 9-16 and Comparative Examples 17-18 was used as the experimental plating solution, and after the experiment, the plated test piece was placed in an oven and baked to 200°C for 1h, and then immediately immersed in 0°C water for quenching. No blistering and peeling of the coating was found.

[0103] 2.5 Test of plating layer flexibility: 1 mm thick A3 steel sheet was passivated with chromium acid, washed and directly hung in the plating solution of Examples 9-16 and Comparative Examples 17-18, and after the thickness of the plating layer reached 20 μm, the plating layer was peeled off, bent 180°, and the plating layer was not broken, indicating that the plating layer was flexible. Among them, Examples 9-16 were better than Example 18, and much better than Example 17.

[0104] 2.6 Test of plating layer porosity: polished iron sheet (A3) with a thickness of 0.5 mm was used, the temperature of the plating solution was 55°C, the cathode current density was 1 A / dm 2 , the time was 20 min, and the porosity test was performed using the filter paper test method with potassium ferricyanide solution.

[0105] Potassium ferricyanide 10 g / L; sodium chloride 20 g / L.

[0106] The experimental results showed that the plating layer formed by the plating solution prepared in Examples 9-16 as the experimental object had a porosity of ≤0.5 / dm 2 , which was better than 1 / dm 2 of Example 18, and much better than 2 / dm 2 of Example 17.

[0107] 2.7 Measurement of deposition rate: the current was set to 1 A, the temperature was 55°C, and the time was 30 min, and the measurement results showed that the deposition rate of the plating solution prepared in Examples 9-16 was 0.75 μm / min, the deposition rate of the plating solution prepared in Example 17 was 0.55 μm / min, and the deposition rate of the plating solution prepared in Example 18 was 0.62 μm / min.

[0108] Further pilot experiments were performed on the plating solutions prepared in Examples 9-16, and the pilot process parameters were as follows:

[0109] Process flow: steel workpiece → ultrasonic oil removal → water washing 1 → water washing 2 → anode electrolytic oil removal → water washing 1 → water washing 2 → acid pickling oil removal → water washing 1 → water washing 2 → hydrochloric acid washing → water washing 1 → water washing 2 → terminal electrolytic oil removal → water washing 1 → water washing 2 → acid activation → water washing 1 → water washing 2 → the plating solution of Examples 9-16 → recovery → water washing 1 → water washing 2 → acid activation → acid copper, and then further plating as needed.

[0110] Ultrasonic oil removal: oil removal powder concentration 50±5 g / L, temperature 70±5°C, current density 1-5 A / dm 2 , time 5 minutes.

[0111] Cathode electrolytic oil removal: electrolytic oil removal powder concentration 50±5 g / L, temperature 70±5°C, current density 1-5 A / dm 2 , time 5-7 minutes.

[0112] Anodic electrolytic degreasing: electrolytic degreasing powder concentration 50±5g / L, temperature 70±5°C, current density 1-5A / dm 2 , time 3-5 minutes.

[0113] Pickling: industrial hydrochloric acid concentration 15-20%, time 8-10 min, room temperature.

[0114] Activation: industrial hydrochloric acid concentration 5-10%, time 3-5 min, room temperature.

[0115] Electroplating solution of Examples 9-16: Baume 32-36, pH 8.0, temperature 50-55°C, current density 0.5-5A / dm 2 , time 5 min to several hours, and it has been proved that the plating to 100 μm is very good in flatness and brightness, better than Comparative Example 18, and much better than Comparative Example 17.

[0116] The electroplating solution prepared in Examples 9-16 has been verified to have reliability and stable performance by continuous running of a 50 L pilot electroplating production line for 20 months and a 350 L pilot electroplating production line for 11 months, and the consumption of the electroplating solution is 10-50 ml / KAH. On the basis of the above-mentioned pilot experiments, the process conditions for industrial production of the electroplating solution prepared in Examples 9-16 are obtained.

[0117] 1. Steel workpiece:

[0118] Process flow: steel workpiece → ultrasonic degreasing → water washing 1 → water washing 2 → anodic electrolytic degreasing → water washing 1 → water washing 2 → pickling degreasing → water washing 1 → water washing 2 → hydrochloric acid washing → water washing 1 → water washing 2 → terminal electrolytic degreasing → water washing 1 → water washing 2 → acid activation → water washing 1 → water washing 2 → pre- immersion → electroplating solution of Examples 9-16 → recovery → water washing 1 → water washing 2 → acid activation → acid copper, and then further electroplating as required.

[0119] Process conditions:

[0120] Electroplating solution density: Baume 32-36

[0121] Temperature 45-60°C

[0122] pH 10-11.5

[0123] Stirring: air stirring plus cathode movement

[0124] Anode: electrolytic copper or oxygen-free electrolytic copper

[0125] Cathode / anode area ratio: 1:1.5-2.

[0126] Current: 0.5-2.5 A / dm 2

[0127] 2. Zinc alloy workpiece:

[0128] Process flow: Zinc alloy workpiece → hot dip wax removal → ultrasonic wax removal → water wash 1 → water wash 2 → ultrasonic oil removal → water wash 1 → water wash 2 → anodic electrolytic oil removal → water wash 1 → water wash 2 → acid salt activation → water wash 1 → water wash 2 → ultrasonic pre-dip pre-dip for 30 seconds → plating solution of Examples 9-16 (charged into tank at 25-35°C) → recovery → water wash 1 → water wash 2 → acid activation → acid copper, and further plating as desired.

[0129] Process conditions:

[0130] Density of plating solution: 32-38 Baume

[0131] Temperature: 25-35°C

[0132] pH: 10-11.5

[0133] Agitation: air agitation plus cathode movement

[0134] Anode: electrolytic copper or oxygen-free electrolytic copper

[0135] Anode to cathode area ratio: 1:1.5-2.

[0136] Current: 0.5-1.5 A / dm 2 .

[0137] The above-described examples are only a preferred embodiment of the present application, and do not limit the present application in any form. Other variations and modifications are possible without departing from the technical solutions recited in the claims.

Claims

1. A non-virulent sodium or potassium cyanide silver plating electroplating solution, characterized in that: The general formula of the silver salt of the complexing agent in the non-toxic cyanide silver plating solution comprising the complexing agent, silver salt of the complexing agent and water is Ag n [C 2n N 2n+1 S n O n H n+3 ] and the structural formula is as follows: Wherein, n is 1, 2, 3, 50.

2. The non-poisonous sodium cyanide or potassium cyanide silver plating solution according to claim 1, characterized in that: The general formula of the complexing agent in the non-poisonous sodium cyanide or potassium cyanide silver plating solution is Rm[C 2m N 2m+1 S m O m H m+3 ] and the structural formula is as follows: Wherein, R is K or Na, m is 1, 2, 3, 50.

3. The non-poisonous sodium or potassium cyanide silver plating solution according to claim 1 or 2, characterized in that: The mass fraction of the complexing agent in the non-toxic cyanide sodium or potassium silver plating solution is 10-30%, the mass fraction of the complexing agent silver salt is 0.8-2.0%, and the rest is water.

4. The non-poisonous sodium or potassium cyanide silver plating solution according to claim 3, characterized in that: The mass fraction of the complexing agent in the non-toxic cyanide sodium or potassium silver plating solution is 20%, the mass fraction of the complexing agent silver salt is 1.5%, and the rest is water.

5. The non-poisonous sodium or potassium cyanide silver plating solution according to claim 1 or 2, characterized in that: The preparation method of the complexing agent silver salt is as follows: water is added to a reactor, and the soluble silver salt and the complexing agent are added to the reaction device, and stirred and reacted at normal temperature and pressure, and after the reaction is completed, the precipitate is rinsed and dried to obtain the complexing agent silver salt.

6. The non-poisonous sodium or potassium cyanide silver plating solution according to claim 2, wherein The preparation method of the complexing agent is as follows: the yellow blood salt, sodium or potassium thiosulfate and urea are used as raw materials, rhodium and / or platinum is used as catalyst in an oxygen-containing atmosphere, and after the solid polymineral salt is reacted and dissolved in water, the complexing agent is obtained by separation, concentration and drying of the separation liquid.

7. The non-vigorous cyanide sodium or potassium silver plating solution of claim 6, characterized in that: The preparation method of the complexing agent is as follows: The yellow blood salt, sodium or potassium thiosulfate and urea are placed in a rotary kiln, and the catalyst rhodium and / or platinum is added, and reacted at 450-650 DEG C for 5-7 hours; the polymerized polymineral salt is dissolved in water, and after separation, the insoluble substances are removed to obtain the separation liquid, and the separation liquid is dried to obtain the finished complexing agent.

8. The non-poisonous sodium cyanide or potassium cyanide silver plating solution according to claim 6 or 7, characterized in that: The separation is any one or several of suction filtration, plate and frame pressure filtration and centrifugal separation.

9. The method for preparing the non-poisonous sodium cyanide or potassium cyanide silver plating solution according to claim 6 or 7, characterized in that: The separation liquid is concentrated before drying, and the separation liquid is concentrated to a water content of 30-40%, and the concentrated material is dried to a water content of less than 5%, the concentration is vacuum concentration, and the drying is spray drying with an air inlet temperature of 100-200 DEG C.

10. The method for preparing the non-poisonous sodium cyanide or potassium cyanide silver plating solution according to any one of claims 1-9, characterized in that: The complexing agent silver salt, the complexing agent and water are mixed according to the proportion, stirred and dissolved, and then the pH value is adjusted to 10.0-11.5 to obtain the non-toxic cyanide sodium or potassium silver plating solution.

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