Method for supplementing metal cations of plating solution in real time during electroplating

Abstract

The invention belongs to the technical field of electroplating, and particularly discloses a real-time supplementing method for plating solution metal cations during electroplating. Aiming at the problems of large concentration fluctuation of metal cations and low supplementing efficiency in the traditional electroplating process, the method realizes dynamic balance of the metal cations through an electroplating synchronous electrolysis and anion exchange membrane technology. According to the technical key points, an electroplating liquid chamber and an electrolyte chamber are separated by adopting an anion exchange membrane; ions are supplemented by electrolyzing a soluble single-metal anode corresponding to metal to be plated, and meanwhile, an electrolytic cathode is arranged in an electrolyte chamber, so that metal deposition is avoided; the ion-selective electrode is used for monitoring the concentration of metal cations in real time, and the electrolytic current is automatically adjusted when the concentration deviation exceeds + / -5%. According to the method, ions are directionally supplemented through electrolysis, plating solution pollution and component fluctuation are avoided, and the uniformity and the qualification rate of a plating layer are improved. And the method is suitable for single-metal and multi-element alloy electroplating systems, can be integrated in processes such as jet electrodeposition and bath plating, is high in adaptability, and has industrial application potential.

Description

Technical Field

[0001] The present invention belongs to the technical field of electroplating, and particularly relates to a method for real-time replenishment of metal cations in a plating solution during electroplating. Background Art

[0002] In the electroplating process, the concentration stability of metal cations (such as Cu 2+ , Ni 2+ , Sn 2+ , etc.) in the plating solution is a key factor determining the quality of the coating. In the traditional electroplating process, the replenishment of metal cations mainly relies on two methods: one is to use a soluble anode, and the cations are directly replenished by the oxidation dissolution of the anode metal. However, this method is limited by the current magnitude of the electroplating process, and the dissolution rate of the replenished cations is uncontrollable. There are often large deviations between the electroplating efficiency of the cathode and the electrolysis efficiency of the anode during electroplating, which will cause the concentration of metal cations in the plating solution to continuously decrease or increase. Especially in the jet electroplating process, the anode may also easily form insoluble residues due to compositional segregation during the dissolution process, resulting in plating solution contamination and pitting defects on the coating surface. Moreover, the non-uniform dissolution on the anode surface will change the inter-electrode gap, causing fluctuations in the current density distribution and affecting the consistency of the coating thickness, especially more significant on the surface of high-curvature workpieces; the other is to use an insoluble anode (such as a titanium-based platinum-coated electrode), and this method requires external intermittent addition of a metal salt solution to maintain the cation concentration. However, frequent manual adjustment or timed liquid replenishment is difficult to accurately match the real-time consumption, easily causing fluctuations in the plating solution composition, increasing the maintenance cost and affecting the electroplating efficiency. Summary of the Invention

[0003] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a method for real-time replenishment of metal cations in a plating solution during electroplating, which is used to solve the problem of unstable concentration of metal cations in the plating solution when using an insoluble anode for electroplating.

[0004] To achieve the above purpose, the present invention provides a method for real-time replenishment of metal cations in a plating solution during electroplating, and the method includes the following steps:

[0005] Step S1, constructing a compartmentalized electroplating-electrolysis cell: separating the plating solution tank into a plating solution chamber and an electrolysis solution chamber through an anion exchange membrane.

[0006] Specifically, the anion exchange membrane only allows anions (such as NO3 - , SO4 2- ) to migrate freely, but blocks the transmembrane diffusion of metal cations (such as Cu 2+ , Sn 2+ , Ni 2+ , etc.), ensuring that the metal cations in the plating solution chamber cannot enter the electrolysis solution chamber. At the same time, the free transmembrane migration of anions provides a current path between the plating solution chamber and the electrolysis solution chamber.

[0007] Step S2, adding electroplating solution and electrolytic solution into the compartment electroplating - electrolytic cell: adding electroplating solution into the electroplating solution chamber and adding electrolytic solution into the electrolytic solution chamber.

[0008] Specifically, the electrolytic solution should be a potassium salt or sodium salt containing a certain anion in the electroplating solution (for example, if the electroplating solution component contains nitrate ions, the electrolytic solution should be potassium nitrate solution or sodium nitrate solution), which ensures the transmembrane migration of anions without introducing new anions into the plating solution and affecting the performance of the original plating solution while ensuring conductivity.

[0009] Step S3, configuring the electroplating assembly: in the electroplating solution chamber, setting the workpiece to be plated as the cathode and connecting it to the negative pole of the electroplating power supply, and setting an insoluble electrode (such as a graphite electrode, a platinum electrode, etc.) as the anode and connecting it to the positive pole of the electroplating power supply.

[0010] Step S4, configuring the electrolysis assembly: in the electroplating solution chamber, setting a soluble single - metal anode corresponding to the metal cation to be plated (such as a pure copper rod, a pure nickel rod, etc.), the composition of which is consistent with the metal cation to be supplemented; in the electrolytic solution chamber, setting a titanium - based cathode (such as a titanium sheet plated with platinum on the surface), where only the hydrogen evolution reaction occurs to avoid metal ion deposition.

[0011] Specifically, the soluble single - metal anode and the titanium - based cathode are respectively connected to the positive and negative poles of the electrolysis power supply. When there are multiple soluble single - metal anodes, multiple electrolysis power supplies need to be set for independent control, and a multi - power independent control architecture is formed with the electroplating system.

[0012] Step S5, configuring the feedback regulation system: putting an ion - selective electrode corresponding to the metal cation to be plated into the electroplating solution. Through the ion - selective electrode, the concentration of the corresponding metal cation in the electroplating solution can be measured, and the concentration signal is input into the corresponding electrolysis power supply. When the concentration fed back to the electrolysis power supply increases or decreases by 5% compared with the initial concentration, the size of the electrolysis current starts to be adjusted.

[0013] Specifically, when the concentration of the metal cation to be plated in the plating solution increases by 5%, the size of the corresponding electrolysis current is automatically reduced; when the concentration of the metal cation to be plated in the plating solution decreases by 5%, the size of the corresponding electrolysis current is automatically increased, so that the fluctuation of the concentration of the metal cation to be plated in the electroplating solution is maintained within 5%.

[0014] Step S6, synchronously operating the electroplating and electrolysis systems: synchronously turning on the electroplating power supply and the electrolysis power supply, adjusting the size of the electroplating current to appropriate parameters, and adjusting the size of the electrolysis current to 20% of the size of the electroplating current.

[0015] The method can be implemented by adapting different electroplating devices, such as jet electroplating devices, tank plating devices, etc. Taking jet electroplating as an example, the device includes a compartmentalized electroplating - electrolytic cell, an electrolysis system, and an electroplating system. The specific device structure is described in detail in the embodiments. Description of the Drawings

[0016] The present invention will be further described below in conjunction with the drawings and embodiments.

[0017] Figure 1 It is a flowchart of a method for real - time replenishment of metal cations in the plating solution during electroplating provided in the present invention.

[0018] Figure 2 It is a schematic diagram of the overall structure of a device for real - time replenishment of metal cations in the plating solution during electroplating provided in an embodiment of the present invention.

[0019] Figure 2 Among them: potassium nitrate electrolysis chamber 1, second titanium - based cathode 2, first titanium - based cathode 3, anion - exchange membrane 4, copper - ion selective electrode 5, tin - ion selective electrode 6, first electrolysis power supply 7, second electrolysis power supply 8, liquid inlet pipeline 9, bolt hole 10, bronze plating solution chamber 11, pure copper rod 12, pure tin rod 13, pump 14, plating solution return pipeline 15, plating solution collection tank 16, workpiece to be plated 17, insoluble anode jet nozzle 18, electroplating power supply 19, flowmeter 20. Detailed Embodiments

[0020] The method in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0021] Embodiment 1

[0022] As Figure 2As shown in the figure, this embodiment provides a real-time replenishment device for metal cations in the plating solution during electroplating. The device includes a compartmentalized electroplating - electrolytic cell, an electrolysis system, and a jet electroplating system. Among them, the compartmentalized electroplating - electrolytic cell is separated into a bronze plating solution chamber 11 and a potassium nitrate electrolysis chamber 1 by an anion exchange membrane 4. The bronze plating solution chamber 11 and the potassium nitrate electrolysis chamber 1 are bolted together through bolt holes 10; the electrolysis system consists of a pure copper rod 12, a first electrolysis power supply 7, a first titanium-based cathode 3, a copper ion selective electrode 5, a pure tin rod 13, a second electrolysis power supply 8, a second titanium-based cathode 2, and a tin ion selective electrode 6; the jet electroplating system consists of a pump 14, a liquid inlet pipe 9, a flow meter 20, an insoluble anode jet nozzle 18, a workpiece to be plated 17, an electroplating power supply 19, a plating solution collection tank 16, and a plating solution return pipe 15.

[0023] Specifically, the anion exchange membrane 4 is a gel polystyrene membrane crosslinked with divinylbenzene, with an ion exchange capacity of 1.3 ± 0.1 meq / g and a membrane thickness of 0.45 ± 0.025 mm. The anion exchange membrane 4 allows anions (such as NO3 - ) to migrate freely, but blocks the transmembrane diffusion of cations (such as Cu 2+ , Sn 2+ ).

[0024] Specifically, the copper ion selective electrode 5 and the tin ion selective electrode 6 are placed in the bronze plating solution chamber.

[0025] Specifically, the pure copper rod 12 and the pure tin rod 13 are placed in the bronze plating solution chamber, and the second titanium-based cathode 2 and the first titanium-based cathode 3 are placed in the potassium nitrate electrolysis chamber.

[0026] Furthermore, the pure copper rod 12 is connected to the positive electrode of the first electrolysis power supply 7, and the pure tin rod 13 is connected to the positive electrode of the second electrolysis power supply 8.

[0027] Furthermore, the first titanium-based cathode 3 is connected to the negative electrode of the first electrolysis power supply 7, and the second titanium-based cathode 2 is connected to the negative electrode of the second electrolysis power supply 8.

[0028] Furthermore, both the first titanium-based cathode 3 and the second titanium-based cathode 2 of the electrolysis system are titanium sheets plated with platinum on the surface. The purity of the titanium sheets is 99.999%, and the thickness of the platinum coating is 1 - 3 μm.

[0029] Furthermore, during electroplating, the electrolysis system is turned on synchronously. The Cu 2+ , Sn 2+ consumed during electroplating is replenished by electrolyzing the pure copper rod 12 and the pure tin rod 13. Only hydrogen evolution reactions occur at the second titanium-based cathode 2 and the first titanium-based cathode 3 of the electrolysis system, avoiding the deposition of metal ions.

[0030] Further, the copper ion selective electrode 5 can measure the concentration of Cu in the bronze plating solution 2+ and feed back the concentration signal of Cu 2+ to the first electrolysis power supply 7. The first electrolysis power supply 7 can dynamically adjust the magnitude of the corresponding electrolysis current according to the concentration signal of Cu 2+ so as to dynamically adjust the replenishment rate of Cuu 2+ and maintain the concentration of Cu in the bronze plating solution chamber 11 2+ at 8 - 12 g / L.

[0031] Further, the tin ion selective electrode 6 can measure the concentration of Sn in the bronze plating solution 2+ and feed back the concentration signal of Sn 2+ to the second electrolysis power supply 8. The second electrolysis power supply 8 can dynamically adjust the magnitude of the corresponding electrolysis current according to the concentration signal of Sn 2+ so as to dynamically adjust the replenishment rate of Sn 2+ and maintain the concentration of Sn in the bronze plating solution chamber 11 2+ at 25 - 35 g / L.

[0032] Specifically, the insoluble anode jet nozzle 18 of the jet electroplating system is made of pure titanium with a platinum coating on the surface. The titanium purity is 99.999%, and the thickness of the platinum coating is 1 - 3 μm. The cathode of the jet electroplating system is the workpiece 17 to be plated.

[0033] Specifically, the plating solution components contained in the bronze plating solution chamber 11 include 18 - 22 g / L of copper pyrophosphate, 50 - 60 g / L of sodium stannate, 250 - 270 g / L of potassium pyrophosphate, 35 - 45 g / L of potassium nitrate, 18 - 22 g / L of potassium sodium tartrate, 28 - 32 g / L of sodium citrate, the pH value is 9.0 - 10.0, and the temperature is 30 - 50 °C. The potassium nitrate concentration contained in the potassium nitrate electrolysis chamber 1 is 50 - 100 g / L, and the pH value is 6.5 - 7.5.

[0034] This embodiment also provides a real - time replenishment method for metal cations in the plating solution during electroplating, including the following steps:

[0035] Step S1, constructing a compartmentalized electroplating - electrolytic cell: using the anion exchange membrane 4 to separate the electroplating - electrolytic cell into a bronze plating solution chamber 11 and a potassium nitrate electrolysis chamber 1, and connecting the bronze plating solution chamber 11 and the potassium nitrate electrolysis chamber 1 by bolts through the bolt holes 10.

[0036] Step S2, adding electroplating solution and electrolytic solution into the compartmentalized electroplating - electrolytic cell.

[0037] Specifically, the bronze plating solution chamber 11 prepares the plating solution components: copper pyrophosphate (Cu2P2O7·4H2O): 20 g / L, sodium stannate (Na2SnO3·3H2O): 55 g / L, potassium pyrophosphate (K4P2O7·H2O): 260 g / L, potassium nitrate (KNO3): 40 g / L, potassium sodium tartrate (C4H4KNaO6·4H2O): 20 g / L, sodium citrate (C6H5Na3O7·2H2O): 30 g / L, pH value: 9.5 (adjusted with phosphoric acid), temperature: 35 °C

[0038] Specifically, the concentration of the potassium nitrate solution prepared in the potassium nitrate electrolysis chamber 1 is 50 g / L, and the pH is 7.0.

[0039] Step S3, configure the electroplating assembly: Connect the workpiece to be plated 17 to the negative electrode of the electroplating power supply 19, connect the insoluble anode jet nozzle 18 to the positive electrode of the electroplating power supply 19, heat the plating solution to 35 °C, start the jet system, and adjust the jet speed to 5 m / s.

[0040] Step S4, configure the electrolysis assembly: Place the pure copper rod 12 and the pure tin rod 13 in the bronze plating solution chamber, place the second titanium-based cathode 2 and the first titanium-based cathode 3 in the potassium nitrate electrolysis chamber, connect the pure copper rod 12 to the positive electrode of the first electrolysis power supply 7, connect the pure tin rod 13 to the positive electrode of the second electrolysis power supply 8, connect the first titanium-based cathode 3 to the negative electrode of the first electrolysis power supply 7, and connect the second titanium-based cathode 2 to the negative electrode of the second electrolysis power supply 8.

[0041] Step S5, configure the feedback adjustment system: Place the copper ion selective electrode 5 and the tin ion selective electrode 6 in the bronze plating solution chamber, connect the copper ion selective electrode 5 to the first electrolysis power supply 7, and connect the tin ion selective electrode 6 to the second electrolysis power supply 8.

[0042] Step S6, synchronously operate the electroplating and electrolysis systems: Control the electroplating cathode current density at 5 A / dm 2 , the plating solution circulation flow rate at 10 L / min, the deposition time at 30 min, and adjust the initial electrolysis current density at 1 A / dm 2 .

[0043] Furthermore, after electroplating, take out the workpiece, ultrasonically clean it with deionized water for 5 min, and then dry it with hot air at 80 °C to obtain a bronze coating.

[0044] Furthermore, test the bronze coating obtained by the device and method in this embodiment and compare it with the bronze coatings obtained using traditional soluble anodes and traditional insoluble anodes under the same electroplating parameters. The results are as follows in the table:

[0045] Example 2

[0046] This embodiment uses a real-time replenishment device for metal cations in the plating solution described in Embodiment 1, and provides a real-time replenishment method for metal cations in the plating solution during electroplating, including the following steps:

[0047] Step S1, construct a compartmentalized electroplating - electrolytic cell: Separate the electroplating - electrolytic cell into a bronze plating solution chamber 11 and a potassium nitrate electrolysis chamber 1 with an anion exchange membrane 4. The bronze plating solution chamber 11 and the potassium nitrate electrolysis chamber 1 are bolt - connected through bolt holes 10.

[0048] Step S2, add electroplating solution and electrolytic solution to the compartmentalized electroplating - electrolytic cell.

[0049] Specifically, the plating solution components in the bronze plating solution chamber 11 are prepared as follows: Copper pyrophosphate (Cu2P2O7·4H2O): 18 g / L, Sodium stannate (Na2SnO3·3H2O): 60 g / L, Potassium pyrophosphate (K4P2O7·H2O): 260 g / L, Potassium nitrate (KNO3): 40 g / L, Potassium sodium tartrate (C4H4KNaO6·4H2O): 20 g / L, Sodium citrate (C6H5Na3O7·2H2O): 30 g / L, pH value: 9.5 (adjusted with phosphoric acid), temperature: 45 °C

[0050] Specifically, the concentration of the potassium nitrate solution configured in the potassium nitrate electrolysis chamber 1 is 50 g / L, and pH is 7.0.

[0051] Step S3, configure the electroplating assembly: Connect the workpiece to be plated 17 to the negative electrode of the electroplating power supply 19, connect the insoluble anode jet nozzle 18 to the positive electrode of the electroplating power supply 19, heat the plating solution to 45 °C, start the jet system, and adjust the jet speed to 5 m / s

[0052] Step S4, configure the electrolysis assembly: Place the pure copper rod 12 and the pure tin rod 13 in the bronze plating solution chamber, place the second titanium - based cathode 2 and the first titanium - based cathode 3 in the potassium nitrate electrolysis chamber. Connect the pure copper rod 12 to the positive electrode of the first electrolysis power supply 7, connect the pure tin rod 13 to the positive electrode of the second electrolysis power supply 8, connect the first titanium - based cathode 3 to the negative electrode of the first electrolysis power supply 7, and connect the second titanium - based cathode 2 to the negative electrode of the second electrolysis power supply 8.

[0053] Step S5, configure the feedback regulation system: Place the copper ion - selective electrode 5 and the tin ion - selective electrode 6 in the bronze plating solution chamber, connect the copper ion - selective electrode 5 to the first electrolysis power supply 7, and connect the tin ion - selective electrode 6 to the second electrolysis power supply 8.

[0054] Step S6, synchronously operate the electroplating and electrolysis systems: Control the electroplating cathode current density at 2.5 A / dm 2, the plating solution circulation flow rate is 10 L / min, the deposition time is 60 min, and the initial electrolysis current density is adjusted to 0.5 A / dm 2 .

[0055] Furthermore, after electroplating is completed, the workpiece is taken out, ultrasonically cleaned with deionized water for 5 min, and then dried with hot air at 80 °C to obtain a bronze coating.

[0056] Furthermore, the bronze coating obtained by using the device and method described in this embodiment is tested and compared with the bronze coatings obtained by using traditional soluble anodes and traditional insoluble anodes under the same electroplating parameters. The results are as follows in the table:

Claims

1. A real-time replenishment method for metal cations in plating solution during electroplating, characterized in that, It includes the following steps: Step S1: Construct a compartmentalized electroplating - electrolytic cell; Step S2: Add electroplating solution and electrolytic solution into the compartmentalized electroplating - electrolytic cell; Step S3: Configure the electroplating assembly; Step S4: Configure the electrolysis assembly; Step S5: Configure the feedback regulation system; Step S6: Synchronously operate the electroplating and electrolysis systems.

2. The real-time replenishment method of metal cations in the plating solution during electroplating according to claim 1, characterized in that The compartmentalized electroplating - electrolytic cell is separated into an electroplating solution chamber and an electrolytic solution chamber by an anion exchange membrane.

3. The real-time replenishing method of metal cations in plating solution during electroplating according to claim 2, characterized in that, The electroplating solution chamber contains the electroplating solution, and the electrolytic solution chamber contains the electrolytic solution.

4. A real-time replenishment method for metal cations in the plating solution during electroplating according to claim 2, characterized in that, The anion exchange membrane only allows anions (such as NO3 - , SO4 2- ) to migrate freely, but blocks the transmembrane diffusion of metal cations (such as Cu 2+ , Sn 2+ , Ni 2+ , etc.), ensuring that the metal cations in the electroplating solution chamber cannot enter the electrolyte chamber. At the same time, the free transmembrane migration of anions provides a current path between the electroplating solution chamber and the electrolyte chamber.

5. The real-time replenishing method of metal cations in plating solution during electroplating according to claim 1, characterized in that, The electrolytic solution is a potassium salt or sodium salt containing a certain anion in the electroplating solution (for example, if the electroplating solution component contains nitrate ions, the electrolytic solution should be potassium nitrate solution or sodium nitrate solution), which ensures that the transmembrane migration of anions does not introduce new anions into the electroplating solution and affect the performance of the original plating solution while ensuring conductivity.

6. A real-time replenishment method for metal cations in the plating solution during electroplating according to claim 1, characterized in that, The anode of the electrolysis assembly is a soluble single - metal anode corresponding to the metal cation to be plated (such as if the metal cation to be plated is copper ion, the electrolysis anode uses a pure copper rod), which is placed in the electroplating solution chamber; the cathode of the electrolysis assembly is a titanium - based cathode (such as a titanium sheet plated with platinum on the surface), which is placed in the electrolytic solution chamber.

7. A real-time replenishment method for metal cations in plating solution during electroplating according to claim 6, characterized in that, The soluble single - metal anode and the titanium - based cathode are respectively connected to the positive and negative electrodes of the electrolysis power supply. When there are multiple soluble single - metal anodes, multiple electrolysis power supplies need to be set up for independent control, and a multi - power - supply independent control architecture is formed with the electroplating system.

8. A real-time replenishment method for metal cations in plating solution during electroplating according to claim 1, characterized in that, The feedback regulation system uses an ion - selective electrode corresponding to the metal cation to be plated. The ion - selective electrode can measure the concentration of the corresponding metal cation in the electroplating solution and input the concentration signal into the corresponding electrolysis power supply. When the concentration fed back to the electrolysis power supply increases or decreases by 5% compared with the initial concentration, the size of the electrolysis current is adjusted.

9. A real-time replenishment method for metal cations in plating solution during electroplating according to claim 1, characterized in that, Synchronously operate the electroplating and electrolysis systems, and the initial size of the electrolysis current is 20% of the electroplating current.

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