Non-toxic sodium cyanide or potassium-copper-tin alloy cyanide electroplating solution and preparation method therefor

Description

Non-poisonous sodium cyanide or potassium cyanide copper-tin alloy electroplating solution and preparation method thereof TECHNICAL FIELD

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

[0002] Electroplated copper-tin alloy is one of the most widely used alloy coatings. Electroplated copper-tin alloy has the advantages of good coating flatness, good brightness, low cost, realistic color, good decorative effect, good smoothness, corrosion resistance and suitable hardness, can prevent the diffusion of the underlying metal to the surface layer, prevent the discoloration of the metal coating, etc. High-cyanide and low-cyanide plating solutions are often used for electroplating copper-tin alloy. The high-cyanide electroplating copper-tin alloy process is the most mature, the plating solution has good dispersing ability, and the composition and color of the coating are easy to control. Although the copper-tin alloy electroplating solution containing cyanide (i.e. cyanide copper-tin electroplating solution) obtained has a fine copper-tin coating, good adhesion, and the plating solution also has good throwing power, leveling and stability. However, cyanide is a highly toxic chemical, and its lethal dose for humans is only 0.005g. Cyanide not only harms the health of operators, but also pollutes the environment, and the treatment of wastewater is difficult and expensive. Therefore, in order to protect the environment and reduce public hazards, it is urgent to develop a non-poisonous sodium cyanide or potassium cyanide copper-tin alloy electroplating solution.

[0003] The inventors of the present application have previously developed a non-cyanide complexing agent. The copper-tin alloy electroplating solution prepared from the complexing agent has stable quality, good dispersibility, and a wide range of process current density that can be used. However, 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 coating 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 in the newly proposed non-cyanide electroplating, the inventors of the present application have developed a new non-poisonous sodium cyanide or potassium cyanide copper-tin alloy electroplating solution and disclosed a preparation method thereof. SUMMARY

[0004] One of the purposes of the present application is to solve the defects of the prior art and provide a new non-poisonous sodium cyanide or potassium cyanide copper-tin alloy electroplating solution. The electroplating solution has strong deep plating capacity, the coating crystal is finer and more compact, the electroplating efficiency is high, and the energy saving of the electroplating process can be achieved.

[0005] The second purpose of the present application is to provide a new preparation method of non-poisonous sodium cyanide or potassium cyanide copper-tin alloy electroplating solution. The method is easy to realize industrial production, and the quality of the electroplating solution product is stable.

[0006] The technical scheme adopted by the present application to solve its technical problems is:

[0007] A non-toxic cyanide copper-tin alloy electroplating solution, comprising a complexing agent, a complexing agent copper salt, a complexing agent tin salt and water, comprising a complexing agent, a complexing agent copper salt, a tin salt and water, wherein the general formula of the complexing agent copper salt in the non-toxic cyanide copper-tin alloy electroplating solution is Cu n [C 2n N 2n+1 S n O n H n+3 , and the structural formula is as follows:

[0008] wherein n is 1, 2, 3, …, 50; the tin salt is potassium stannate or sodium stannate.

[0009] Preferably, the general formula of the complexing agent in the non-toxic cyanide copper-tin alloy electroplating solution is R m [C 2m N 2m+1 S m O m H m+3 , and the structural formula is as follows:

[0010] wherein R is K or Na, and m is 1, 2, 3, …, 50.

[0011] The foregoing technical solutions are explained below with several examples:

[0012] 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:

[0013] The structural formula of the complexing agent copper salt obtained by processing this complexing agent is Cu[C2N3SOH4], n=m, and the structural formula is as follows:

[0014] B: when R is K and n is 20, the general formula of the complexing agent is K 20 [C 40 N 41 S 20 O 20 H 23 , and the structural formula is as follows:

[0015] The structural formula of the complexing agent copper salt obtained by processing this complexing agent is as follows:

[0016] 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 O50 H 53 ],its structural formula is as follows:

[0017] The structural formula of the complexing agent copper salt processed by the complexing agent is as follows:

[0018] Preferably, R is K, n is 1, 2, 3, and the structural formula is as follows:

[0019] Preferably, in the non-toxic cyanide sodium or potassium copper tin electroplating solution, the mass fraction of the complexing agent is 15-25%, the mass fraction of the complexing agent copper salt is 0.5-1.5%, the mass fraction of the tin salt is 2-4%, and the balance is water.

[0020] More preferably, in the non-toxic cyanide sodium or potassium copper tin electroplating solution, the mass fraction of the complexing agent is 20%, the mass fraction of the complexing agent copper salt is 1.0%, the mass fraction of the tin salt is 3%, and the balance is water.

[0021] In the non-toxic cyanide sodium or potassium copper tin alloy electroplating solution of the application, at least the complexing agent copper salt is prepared by reacting the complexing agent of the application with a soluble copper salt, and the complexing agent in the preparation of the electroplating solution can be selected from conventional complexing agents, the complexing agent of the application, and preferably the complexing agent of the application.

[0022] The n value in the complexing agent copper salt and the tin salt can be the same or different, and can be the same as or different from the m value in the complexing agent. For example, the complexing agent in the aforementioned A is mixed with the complexing agent copper salt in the aforementioned A or the complexing agent copper salt in the aforementioned B, which can be processed into the non-toxic cyanide sodium or potassium copper tin alloy electroplating solution of the application.

[0023] Preferably, the complexing agent is prepared from yellow blood salt, sodium or potassium thiosulfate (when R is K, potassium thiosulfate is used, and when R is Na, sodium thiosulfate is used) and urea as raw materials, in an oxygen-containing atmosphere, with rhodium and / or platinum as catalyst, after solid-state polymineral salt reaction, dissolved in water, and then separated, concentrated and dried.

[0024] The reaction formula of the complexing agent preparation method of the 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 / 4)N2+nNa2SO3+(n-1)NH3,

[0025] (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;

[0026] The application also discloses a preparation method of the complexing agent, which comprises the following steps:

[0027] The thiocyanate, sodium thiosulfate or potassium thiosulfate and urea are placed in a rotary reaction kiln, in which a catalyst rhodium and / or platinum is fixed, and reacted in an oxygen-containing atmosphere at 450-650℃ for 5-7 hours; the polymerized polymineral salt is dissolved in water, and then separated to remove insoluble substances to obtain a separated liquid, which is dried to obtain the finished complexing agent.

[0028] Preferably, the separation is performed by any one or more of suction filtration, plate-frame pressure filtration and centrifugal separation.

[0029] 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%; the concentration is performed by vacuum concentration.

[0030] Preferably, the drying is performed by spray drying, and the inlet air temperature of the spray drying is 100-200℃.

[0031] The preparation method of the complexing agent copper salt is as follows: water is added into a reactor, then a molar amount of the complexing agent and a water-soluble copper salt are added, and then a molar amount of sodium sulfite and sodium hydroxide are added, and the reaction is performed by stirring, and the precipitate obtained by filtering after the reaction is completed is rinsed and dried to obtain the complexing agent copper salt.

[0032] The preparation method of the non-toxic sodium cyanide or potassium cyanide copper-tin alloy electroplating solution of the application is as follows: the complexing agent copper salt, tin salt, complexing agent and water are mixed according to the proportion, stirred and dissolved, and then the pH value is adjusted to 12.0-13 to obtain the non-toxic sodium cyanide or potassium cyanide copper-tin electroplating solution.

[0033] The application has the following beneficial effects:

[0034] The preparation raw material of the complexing agent is widely sourced, low in price, simple in preparation process, transportation, storage and use, and low in production cost; the complexing agent is applied to the production of electroplating liquid, convenient to process, and the prepared electroplating liquid has strong complexing capacity for metals, for example, the complexing constant of the complexing agent for copper ions can reach 10 26-27 (Comparing with the cyanide-free complexing agent in the prior art), far superior to the conventional complexing agent (mainly potassium pyrophosphate, citric acid and HEDP) in the prior art, the copper-tin alloy electroplating liquid prepared from the complexing agent has stable quality, good dispersibility, a wide range of process current density that can be used, and a wide application range of the electroplating liquid (such properties are comparable to the electroplating liquid prepared from the cyanide-free complexing agent in the prior art), in addition, the complexing agent has strong plating capacity, the plating layer is more delicate and dense, the electroplating efficiency is high, and energy saving of the copper-tin alloy electroplating process can be achieved. DETAILED DESCRIPTION

[0035] 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.

[0036] Example 1

[0037] A complexing agent, the structural formula of which is as follows:

[0038] The reaction formula of the polymeric inorganic salt of the complexing agent is as follows:

[0039] (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:

[0040] The yellow prussiate, sodium or potassium thiosulfate and urea are placed in a rotary reaction kiln, the rotary reaction kiln is fixed with a catalyst rhodium and / or platinum, in an oxygen-containing atmosphere, at 450-460℃, and reacted for 7 hours; the polymeric inorganic salt is dissolved in water, insoluble substances are removed through separation to obtain a separation liquid, and the separation liquid is dried to obtain the finished complexing agent.

[0041] In Example 1, the separation is performed by suction filtration, and the separation liquid is concentrated before drying, the separation liquid is concentrated to a water content of 30%, 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℃.

[0042] Example 2

[0043] A complexing agent, the structural formula of which is as follows:

[0044] The polymineral salt reaction formula of the complexing agent is as follows:

[0045] (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:

[0046] 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, in an oxygen-containing atmosphere, at 640-650℃, for 5 hours; 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 complexing agent finished product.

[0047] In Example 1, the separation uses plate-frame pressure filtration, and the separated liquid is concentrated before drying, to a water content of 40%; the concentrated material is dried to a water content of less than 5%; the concentration uses vacuum concentration, and the drying uses spray drying, with an air inlet temperature of 190-200℃.

[0048] Example 3

[0049] A complexing agent, the structural formula of which is as follows:

[0050] 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:

[0051] 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, in an oxygen-containing atmosphere, at 590-600℃, for 6 hours; 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 complexing agent finished product.

[0052] In Example 3, the separation uses centrifugal separation, and the separated liquid is concentrated before drying, to a water content of 35%; the concentrated material is dried to a water content of less than 5%; the concentration uses vacuum concentration, and the drying uses spray drying, with an air inlet temperature of 160-170℃.

[0053] Example 4

[0054] A complexing agent, the structural formula of which is the same as that of Example 3, except that n = 50.

[0055] Example 5

[0056] A complexing agent, the structural formula of which is the same as that of Example 1, except that Na is used instead of K.

[0057] Example 6

[0058] A complexing agent, the structural formula of which is the same as that of Example 2, except that Na is used instead of K.

[0059] Example 7

[0060] A complexing agent, the structural formula of which is the same as that of Example 3, except that Na is used instead of K.

[0061] Example 8

[0062] A complexing agent, the structural formula of which is the same as that of Example 4, except that Na is used instead of K.

[0063] The complexing agents of Examples 1-8 of the present application are used for electroplating. Taking an electroplating solution for pre-plating copper-tin as an example, the amount of the complexing agent in the electroplating solution is 1-40%, preferably 20%. The application of the complexing agents of the present application is illustrated by taking the amount of 20% as an example.

[0064] The reaction formula for preparing a complexing agent copper salt from the complexing agent is as follows, taking n = 2 and R = K as an example.

[0065] 2CuSO4+ K2[C4N5S2O2H5] + Na2SO3 + 2NaOH = K2SO4 + 2Na2SO4 + H2O + Cu2[C4N5S2O2H5]. The reaction condition is a reaction at normal temperature and pressure.

[0066] Example 9: The complexing agent of Example 1 is used in an electroplating solution for pre-plating copper-tin

[0067] Water is added to a reaction kettle, the complexing agent of Example 1 is added in a molar amount, a copper salt (copper sulfate or copper chloride) is added in a molar amount, and sodium sulfite and sodium hydroxide are added in a molar amount. The mixture is stirred to react. After the reaction is completed, the precipitate is filtered, rinsed, and dried to obtain a complexing agent copper salt.

[0068] The electroplating solution is prepared as follows: the complexing agent is 20%, the complexing agent copper salt is 1.0%, potassium stannate is 3.0%, and the rest is water. The mixture is mixed uniformly, and the pH is adjusted to 11.0 by sodium hydroxide.

[0069] Example 10: Electroplating solution for pre-plating copper using the complexing agent of Example 2

[0070] Water was added to a reaction kettle, the complexing agent of Example 2 was added in a molar ratio, a molar amount of copper salt (copper sulfate or copper chloride) was added, and a molar amount of sodium sulfite and sodium hydroxide was added. The mixture was stirred and reacted. After the reaction was completed, the precipitate was filtered, rinsed, and dried to obtain a complexing agent copper salt.

[0071] The electroplating solution was prepared by mixing 20% of the complexing agent, 1.0% of the complexing agent copper salt, 3.0% of potassium stannate, and the rest water, and adjusting the pH to 13.0 using sodium hydroxide.

[0072] Example 11: Electroplating solution for pre-plating copper using the complexing agent of Example 3

[0073] Water was added to a reaction kettle, the complexing agent of Example 3 was added in a molar ratio, a molar amount of copper salt (copper sulfate or copper chloride) was added, and a molar amount of sodium sulfite and sodium hydroxide was added. The mixture was stirred and reacted. After the reaction was completed, the precipitate was filtered, rinsed, and dried to obtain a complexing agent copper salt.

[0074] The electroplating solution was prepared by mixing 20% of the complexing agent, 1.0% of the complexing agent copper salt, 3.0% of potassium stannate, and the rest water, and adjusting the pH to 12.0 using sodium hydroxide.

[0075] Examples 12-16: Electroplating solution for pre-plating copper-tin using the complexing agents of Examples 4-8, respectively

[0076] Water was added to a reaction kettle, the complexing agents of Examples 4-8 were added in a molar ratio, a molar amount of copper salt (copper sulfate or copper chloride) was added, and a molar amount of sodium sulfite and sodium hydroxide was added. The mixture was stirred and reacted. After the reaction was completed, the precipitate was filtered, rinsed, and dried to obtain a complexing agent copper salt.

[0077] The electroplating solution was prepared by mixing 20% of the complexing agent, 1.0% of the complexing agent copper salt, 3.0% of potassium stannate, and the rest water, and adjusting the pH to 12.0 using sodium hydroxide.

[0078] Comparative Example 17: Potassium pyrophosphate complexing agent

[0079] The electroplating solution was prepared by mixing 20% of the complexing agent, 1.0% of copper pyrophosphate, 3.0% of potassium stannate, and the rest water, and adjusting the pH to 12.0 using sodium hydroxide.

[0080] Comparative Example 18: Complexing agent of Patent No. 2014100151872

[0081] The plating bath was prepared by mixing the following ingredients: complexing agent 20%, complexing agent copper salt 1.0%, complexing agent tin salt 3.0%, and the balance water, and adjusting the pH to 12.0 with sodium hydroxide.

[0082] Performance tests:

[0083] The above examples 9-16, comparative examples 17-18 were subjected to performance tests according to the following methods.

[0084] The non-toxic cyanide copper-tin plating baths prepared from examples 9-16 and comparative examples 17-18 were subjected to the following studies:

[0085] 1. Hull cell test (267 ml)

[0086] 1.1 Preliminary test: The non-toxic cyanide copper-tin plating baths prepared from examples 9-16 and comparative examples 17-18 were subjected to sheet plating at a temperature of 25°C, circuit 1A (constant current), air agitation, for a time of 5 minutes. During sheet plating, it was observed that the bath voltage was relatively stable under constant current conditions and the plated sheets exhibited semi-spots and fine crystals over a large area. Examples 9-16 were superior to comparative example 18, which was superior to comparative example 17.

[0087] 1.2 Hull cell test to determine the current density range:

[0088] The non-toxic cyanide copper-tin plating baths prepared from examples 9-16 and comparative examples 17-18 were subjected to sheet plating in a Hull cell at a temperature of 55°C, current 1A, for a time of 10 minutes, to determine the optimum current density range. The sheet material used for sheet plating was A3 steel sheet of 0.5*70*100, polished with 600# water sandpaper. The current density at each point of the test sheet was calculated using the empirical formula Jk = I (5.1-5.24 LgL). Through sheet plating and current density calculation, it was found that the current density range of the plating bath prepared from examples 9-16 was between 0.5 A / dm 2 and 5 A / dm 2 .

[0089] 2. Plating bath and plating performance tests

[0090] 2.1 Measurement of current efficiency: The current efficiency of the plating baths prepared from examples 9-16 was 94.2% on average, the current efficiency of the plating bath prepared from example 17 was 90.8%, and the current efficiency of the plating bath prepared from example 18 was 92.8%.

[0091] 2.2 Measurement of plating bath throwing power

[0092] The dispersing power 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, which was polished with 600# water sandpaper.

[0093] The average dispersing power of the plating solution of Examples 9-16 was measured to be 94.4%, the dispersing power of the plating solution of Example 17 was 90.1%, and the dispersing power of the plating solution of Example 18 was 92.4%.

[0094] 2.3 Measurement of covering power

[0095] The covering power 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 plating layer inside the pipe was observed.

[0096] The non-toxic sodium cyanide or potassium cyanide copper-tin 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 a copper-tin alloy layer, indicating that the covering power of the plating solution prepared from Examples 9-16 was excellent, better than that of Example 18, and much better than that of Example 17.

[0097] 2.4 Bonding force test

[0098] 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.

[0099] The non-toxic sodium cyanide or potassium cyanide copper-tin 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 plating layer and the substrate did not separate.

[0100] 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.

[0101] The non-toxic sodium cyanide or potassium cyanide copper-tin 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 1 h, and then immediately immersed in 0°C water for quenching. No blistering and peeling of the plating layer was found.

[0102] 2.5 Test of plating layer flexibility: A 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. After the thickness of the plating layer reached 20 μm, the plating layer was peeled off, bent 180°, and pressed at the bent part. The plating layer did not break, indicating that the plating layer was flexible. Examples 9-16 were superior to Example 18, and Example 18 was superior to Example 17.

[0103] 2.6 Test of plating layer porosity: A 0.5 mm thick polished iron sheet (A3) 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.

[0104] Potassium ferricyanide 10 g / L; sodium chloride 20 g / L.

[0105] The test results showed that the plating layer formed from the plating solution of Examples 9-16 as the test object had a porosity of ≤0.5 / dm 2 , which was superior to 1 / dm 2 of Example 18, and superior to 2 / dm 2 of Example 17.

[0106] 2.7 Measurement of deposition rate: The current was set to 1 A, the temperature was 55°C, and the time was 30 min. The results showed that the deposition rate of the plating solution of Examples 9-16 was 0.76 μm / min, the deposition rate of the plating solution of Example 17 was 0.55 μm / min, and the deposition rate of the plating solution of Example 18 was 0.64 μm / min.

[0107] Further pilot test was performed on the plating solution of Examples 9-16. The pilot process parameters were as follows:

[0108] 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 further plating treatment as needed.

[0109] Ultrasonic oil removal: oil removal powder concentration 50±5 g / L, temperature 70±5°C, current density 1-5 A / dm 2 , time 5 min.

[0110] 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 min.

[0111] Anodic electrolytic degreasing: electrolytic degreasing powder concentration 50±5g / L, temperature 70±5℃, current density 1-5A / dm 2 , time 3-5 minutes.

[0112] Pickling: industrial hydrochloric acid concentration 15-20%, time 8-10 min, room temperature.

[0113] Activation: industrial hydrochloric acid concentration 5-10%, time 3-5 min, room temperature.

[0114] Electroplating solution of Examples 9-16: Baume 32-36, pH 8.0, temperature 50-55℃, current density 0.5-5A / dm 2 , time 5 min to several hours, and it has been proved that the plating to 100μm is very good in flatness and brightness, better than Comparative Example 18, and much better than Comparative Example 17.

[0115] The electroplating solution prepared in Examples 9-16 has been verified to be reliable and stable in performance by continuous running of 50L pilot electroplating production line for 20 months and 350L pilot electroplating production line for 11 months, and the consumption of the electroplating solution is 10-50ml / 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.

[0116] 1. Steel workpiece:

[0117] 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 further electroplating treatment as required.

[0118] Process conditions:

[0119] Electroplating solution density: Baume 32-36

[0120] Temperature 45-60℃

[0121] pH 11-13

[0122] Stirring: air stirring plus cathode movement

[0123] Anode: electrolytic copper or oxygen-free electrolytic copper

[0124] Anode / cathode area ratio: 1:1.5-2.

[0125] Current: 0.5-5A / dm 2

[0126] 2. Tin alloy workpiece:

[0127] Process flow: Tin alloy workpiece → Hot dip de-waxing → Ultrasonic de-waxing → Water wash 1 → Water wash 2 → Ultrasonic de-oiling → Water wash 1 → Water wash 2 → Anodic electrolytic de-oiling → Water wash 1 → Water wash 2 → Acid salt activation → Water wash 1 → Water wash 2 → Ultrasonic pre-dip pre-dipping for 30 seconds → Electroplating solution of Examples 9-16 (charged into tank at 25-35°C) → Recovery → Water wash 1 → Water wash 2 → Acid activation → Acid copper, further electroplating treatment as required.

[0128] Process conditions:

[0129] Density of electroplating solution: 32-38 Baume

[0130] Temperature: 25-35°C

[0131] pH: 11-13

[0132] Agitation: air agitation plus cathode movement

[0133] Anode: electrolytic copper or oxygen-free electrolytic copper

[0134] Ratio of anode to cathode area: 1:1.5-2.

[0135] Current: 0.5-1.5 A / dm 2 .

[0136] The above-described examples are only a preferred embodiment of the present application, and do not limit the present application in any form, and 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 copper-tin alloy electroplating solution characterized in that: The non-poisonous sodium cyanide or potassium cyanide copper-tin alloy electroplating solution comprises a complexing agent, a complexing agent copper salt, a tin salt and water, and the general formula of the complexing agent copper salt is Cu 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; tin salt is potassium stannate or sodium stannate.

2. The non-venomous sodium or potassium cyanide copper-tin alloy electroplating solution according to claim 1, characterized in that: The general formula for the complexing agent in the non-toxic sodium cyanide or potassium cyanide copper-tin alloy electroplating solution is R. m [C 2m N 2m+1 S m O m H m+3 Its 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 copper-tin alloy electroplating 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 copper-tin alloy electroplating solution is 15-25%, the mass fraction of the complexing agent copper salt is 0.5-1.5%, the mass fraction of the tin salt is 2-4%, and the rest is water.

4. The non-poisonous sodium or potassium cyanide copper-tin alloy electroplating solution according to claim 3, characterized in that: The mass fraction of the complexing agent in the non-toxic cyanide sodium or potassium copper-tin alloy electroplating solution is 20%, the mass fraction of the complexing agent copper salt is 1.0%, the mass fraction of the tin salt is 3%, and the rest is water.

5. The non-poisonous sodium or potassium cyanide copper-tin alloy electroplating solution according to claim 1 or 2, characterized in that: The preparation method of the complexing agent copper salt is as follows: a reactor is added with water, then added with a molar amount of the complexing agent and a water-soluble copper salt, and then added with a molar amount of sodium sulfite and sodium hydroxide, and stirred to react, and after the reaction is completed, the precipitate is obtained by filtration, rinsing and drying to obtain the complexing agent copper salt.

6. The non-poisonous sodium or potassium cyanide copper-tin alloy electroplating solution according to claim 2, wherein The preparation method of the complexing agent is as follows: hemin, sodium or potassium thiosulfate and urea are used as raw materials, rhodium and / or platinum is used as a catalyst in an oxygen-containing atmosphere, and after a solid-state 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-violent cyanide sodium or potassium copper-tin alloy electroplating solution of claim 6, characterized in that: The preparation method of the complexing agent is as follows: Hemin, sodium or potassium thiosulfate and urea are placed in a rotary kiln, the rotary kiln is fixed with a catalyst rhodium and / or platinum, and in an oxygen-containing atmosphere, the reaction is carried out at 450-650℃ for 5-7 hours; the polymerized polymineral salt is dissolved in water, the insoluble substances are removed by separation to obtain a separation liquid, and the separation liquid is dried to obtain the finished complexing agent.

8. The non-poisonous sodium or potassium cyanide copper-tin alloy electroplating 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-toxic sodium cyanide or potassium cyanide copper-tin alloy electroplating solution according to claim 6 or 7, characterized in that: The separation liquid is concentrated before drying, the separation liquid is concentrated to a water content of 30-40%, 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℃.

10. The process for the preparation of the non- violent cyanide sodium or potassium copper-tin alloy electroplating solution according to any one of claims 1 to 9, characterized in that: The complexing agent copper salt, the tin salt, the complexing agent and water are mixed according to the proportion, stirred and dissolved, and then the pH value is adjusted to 12.0-13 to obtain the non-toxic cyanide sodium or potassium copper-tin alloy electroplating solution.

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