Copper dissolving tank based on iron ion copper plating system

Abstract

The invention discloses a copper dissolving tank based on an iron ion copper plating system, which belongs to the field of electrolytic baths for electrolytic plating, and comprises an outer cylinder, a base, an inner cylinder and a shell, a titanium rod penetrates through the center of the inner cylinder, the top end of the titanium rod is connected with an anode, the inner cylinder is arranged in the outer cylinder, copper particles are filled between the inner cylinder and the outer cylinder, a titanium basket is arranged between the copper particles and the inner wall of the outer cylinder, a copper ring is fixedly arranged at the top of the titanium basket along the cylinder wall direction of the outer cylinder, and a cathode is connected above the copper ring; according to the method, the area of the anode is reduced, the area of the cathode is increased, and the average current density of the cathode is reduced, so that ferric ions in contact with the surfaces of the copper particles are subjected to reduction reaction, the concentration of the ferric ions is reduced, regeneration of the ferric ions is realized, and meanwhile, the reaction of metal copper and ferric ions is reduced, so that the dissolution rate of copper is controlled. Therefore, when the concentration of the copper ions in the electroplating solution is in a specified range of the copper plating solution, the concentration of the ferric ions is also in a lower range, the electroplating efficiency is improved, and the additional consumption of copper is controlled.

Description

Technical Field

[0001] The present invention belongs to the field of electrolytic cells for electrolytic plating, and relates to an electrolytic copper plating device for PCB, and particularly to a copper dissolving tank based on an iron ion copper plating system. Background Art

[0002] In the production process of PCB circuit boards, electroplating copper operation is required to improve electrical conductivity and the bonding force of the coating with other metals. According to the anode characteristics, the electroplating copper process is divided into two copper plating methods, namely soluble anode and insoluble anode. The soluble anode directly uses phosphor bronze balls as the anode. During electroplating, metallic copper dissolves to supplement copper ions, and during production, copper is supplemented by adding phosphor bronze balls. This method requires regular cleaning due to the formation of anode films and anode slime adhering to the phosphor bronze balls, increasing labor costs, reducing production efficiency, and causing waste of phosphor bronze balls.

[0003] The insoluble anode uses a titanium basket as the anode, which does not produce anode films and anode slime, does not require manual cleaning of the copper anode, and there is no waste, so the efficiency is high and the electroplating quality is good. The insoluble anode is divided into a ferric ion copper dissolving system and a copper oxide powder dissolving system according to the copper ion supplement method; in the copper oxide powder system, the control of copper ion concentration is relatively simple, and the reaction formula is: CuO + 2H + = Cu 2+ + H 2 O; however, copper oxide is prepared by oxidizing copper powder, increasing the processing cost of copper, and the copper cost is relatively high. At the same time, the titanium electrode will absorb oxygen, resulting in the need for a very thick iridium oxide coating on the insoluble titanium anode, with a high cost. At the same time, oxygen evolution will consume a large amount of electroplating brightener, increasing the cost; the ferric ion copper dissolving system generates copper ions through the reaction of ferric ions and copper, and the reaction formula is: 2Fe 3+ + Cu = Cu 2+ + 2Fe 2+ , and the anode will not have an oxygen absorption reaction, and its comprehensive cost is the lowest. However, in the current copper dissolving tanks on the market (please refer to Figure 4 shown), the electroplating solution enters from the chemical solution inlet below the copper dissolving tank, and after fully contacting with the metallic copper in the filter barrel, the ferric ions in the chemical solution oxidize the metallic copper into copper ions and then flow out from the upper part. Limited by its structural design, there are many copper particles and a large mass in the filter barrel. After one month of use, the problem of filter barrel deformation will occur, and the electroplating chemical solution dissolved by this copper dissolving tank cannot effectively regulate the ferric ion concentration and copper ion concentration. When the number of copper particles is increased or (and) the flow rate is increased, the ferric ion concentration can be controlled at a lower level, but the copper ion concentration will gradually rise beyond the upper limit. If the number of copper particles is reduced or (and) the flow rate is decreased, the copper ion concentration can be stabilized, but the ferric ions will gradually rise, resulting in a significant reduction in electroplating efficiency and insufficient electroplated copper thickness.

[0004] The Chinese patent application with the publication number CN117488390A discloses a device for controlling the concentration of electrolytic ions and its usage method. By setting an anode workpiece, including a non-oxygen-evolving insoluble titanium basket anode basket and pure copper grains filled in the non-oxygen-evolving insoluble titanium basket anode basket, and an ion membrane is set on the cathode, it can eliminate the additional copper dissolution tank equipment in the electroplating area, improve the copper dissolution efficiency, reduce energy consumption, and ensure the stability of the metal copper ion concentration in the electroplating area. However, anode mud is likely to be generated on the surface of the ion membrane, affecting the ion passage efficiency, and at the same time, the trivalent iron concentration cannot be controlled within a lower range (such as less than 1 g / L).

[0005] A trivalent iron copper dissolution circulation replenishment device with the publication number CN115478309A, through an electroplating solution circulation mechanism, a trivalent iron ion generation mechanism, and an electroplated copper ion generation mechanism, converts divalent iron ions in the electroplating solution into trivalent iron ions, makes pure copper react with trivalent iron ions in the electroplating solution to generate divalent iron ions and electroplated copper ions, and then transports them into the electroplating main tank.

[0006] The above-mentioned solution dissolves copper through an external device and transports it to the electroplating area for electroplating to improve the copper dissolution efficiency and copper plating efficiency of copper ions. The additional device needs to control the ion concentration entering the electroplating tank. During the process of generating trivalent iron ions and copper ions, when the copper ion concentration is controlled within the specified range of the copper plating solution, as the copper plating process progresses, the trivalent iron ion concentration will correspondingly increase, resulting in a reduction in electroplating efficiency by more than 10%. When controlling the reduction of the trivalent iron ion concentration, the copper ion concentration will increase, causing the copper ion concentration to be outside the specified range of the copper plating solution and requiring dilution, resulting in copper waste and an increase in the workload of wastewater treatment. Summary of the Invention

[0007] The purpose of the present invention is to provide a copper dissolution tank based on an iron ion copper plating system, so that when the copper ion concentration is within the specified range of the copper plating solution during the electroplating copper operation, the trivalent iron ion concentration is also within a lower concentration range, improving the electroplating efficiency.

[0008] The purpose of the present invention can be achieved through the following technical solutions: A copper dissolution tank based on an iron ion copper plating system includes an outer cylinder and a base, and also includes an inner cylinder and a housing.

[0009] A titanium rod is centrally penetrated through the inner cylinder, the top of the titanium rod is connected to the anode, the inner cylinder is arranged inside the outer cylinder, copper grains are filled between the inner cylinder and the outer cylinder, a titanium basket is arranged between the copper grains and the inner wall of the outer cylinder, a copper ring is fixedly arranged at the top of the titanium basket along the direction of the outer cylinder wall, and the cathode is connected above the copper ring.

[0010] A housing is arranged outside the outer cylinder, an overflow box is arranged at the upper end of the housing, an overflow port is opened and communicated to the overflow box, and an outlet is arranged at the bottom of the overflow box.

[0011] Furthermore, the titanium rod is coated with iridium dioxide, a plastic pipe is sleeved outside the titanium rod, and a filter cloth is wrapped outside the plastic pipe.

[0012] Furthermore, the plastic pipe is made of a rigid insulating material, with holes on its four sides and no holes at the bottom.

[0013] Furthermore, the titanium basket is arranged along the inner side of the outer cylinder wall, with one side in contact with the copper particles and the other side in contact with the inner wall of the outer cylinder.

[0014] Furthermore, the inner cylinder is evenly drilled on its four sides, and a filter cloth is wrapped outside the inner cylinder.

[0015] Furthermore, a base is fixedly arranged below the outer cylinder, a fixing plate is arranged between the outer cylinder and the base, diagonal bracing plates are arranged around the lower end of the outer cylinder, the bottom of the diagonal bracing plates is fixed to the fixing plate, and inlets are arranged at the bottom of the outer cylinder on both sides of the diagonal bracing plates.

[0016] Furthermore, a cover plate is arranged at the top of the outer shell, and the cover plate seals the tops of the inner cylinder, the outer cylinder, and the outer shell.

[0017] Furthermore, external reinforcing ribs are equidistantly arranged on the outer shell, and internal reinforcing ribs are equidistantly arranged on the outside of the inner cylinder.

[0018] Furthermore, an observation window is arranged on the cover plate, and a funnel is arranged on the cover plate. The bottom opening of the funnel is arranged between the inner cylinder and the outer cylinder.

[0019] Furthermore, the voltage of the regeneration rectifier externally connected to the cathode and the anode is 0 - 6V, the anode current density is 5 - 10 ASD, the Fe concentration in the plating solution in the electrolytic regeneration copper dissolution tank is < 1 g / L, and the concentration of CuSO₄·5H₂O is 65 - 75 g / L. 3+ concentration < 1 g / L, CuSO₄ 4 ·5H₂ 2 O is 65 - 75 g / L.

[0020] Advantages of the present invention: By increasing the area ratio of the cathode region to the anode region in the present invention, the area ratio of the cathode to the anode exceeds 1000:1. By increasing the cathode area (the sum of the surface areas of all copper particles), the average current density of the cathode is reduced, enabling the ferric ions in contact with the surface of the copper particles to undergo a reduction reaction, reducing the ferric ion concentration, realizing the regeneration of ferrous ions, and at the same time reducing the reaction between metallic copper and ferric ions, thereby controlling the dissolution rate of copper. When the copper ion concentration in the plating solution is within the specified range of the copper plating solution, the ferric ion concentration is also in a relatively low range, improving the electroplating efficiency and controlling the additional consumption of copper. Description of the drawings

[0021] The following further describes the present invention with reference to the drawings.

[0022] Figure 1It is a schematic cross-sectional view of a copper dissolution tank based on an iron ion copper plating system according to the present invention; Figure 2 It is Figure 1 The enlarged view at position A in Figure 3 It is Figure 1 The enlarged view at position B in Figure 4 It is a schematic cross-sectional view of a copper dissolution tank in the prior art; In the figure: 1. Anode; 101. Titanium rod; 102. Plastic pipe; 2. Cathode; 201. Titanium basket; 202. Copper ring; 203. Copper particles; 3. Outer cylinder; 301. External reinforcing rib; 303. Inlet; 4. Inner cylinder; 401. Internal reinforcing rib; 5. Outer shell; 501. Cover plate; 502. Funnel; 503. Overflow port; 504. Overflow box; 505. Outlet; 6. Base; 601. Fixed plate; 602. Diagonal stay plate; 7. Metallic copper; 8. Filter barrel; 9. Pressure gauge; 10. Chemical solution outlet; 11. PP mesh plate; 12. Support frame; 13. Chemical solution inlet; 14. External housing. Detailed implementation manners

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described 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. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] Embodiment Please refer to Figure 1 As shown, a copper dissolution tank based on an iron ion copper plating system is composed of an inner cylinder 4, an outer cylinder 3, an outer shell 5 and a base 6.

[0025] Please refer to Figure 1 And Figure 2 As shown, a titanium rod 101 is centrally penetrated in the inner cylinder 4. The surface of the titanium rod 101 is coated with iridium dioxide. The top end of the titanium rod 101 is connected to the anode 1. A plastic pipe 102 is sleeved outside the titanium rod 101. The plastic pipe 102 is made of HPVC hard insulating material. The plastic pipe 102 is perforated around and not perforated at the bottom. A filter cloth is wrapped outside the plastic pipe 102 to allow the oxygen generated by the titanium rod 101 to leave the surface of the titanium rod 101.

[0026] Please refer to Figures 1-3 As shown, the inner cylinder 4 is arranged inside the outer cylinder 3. Copper particles 203 are filled between the inner cylinder 4 and the outer cylinder 3. The inner cylinder 4 is made of PP material. The inner cylinder 4 is evenly perforated around, and the perforated area is 70-80%. A filter cloth is wrapped outside the inner cylinder 4 to prevent the copper particles 203 from entering the inner cylinder 4. The outer cylinder 3 is made of NPP translucent material.

[0027] A titanium basket 201 is arranged between the copper particles 203 and the inner wall of the outer cylinder 3. The titanium basket 201 is arranged around the inner side of the wall of the outer cylinder 3. One side of the titanium basket 201 is in contact with the copper particles 203, and the other side is in contact with the inner wall of the outer cylinder 3. A copper ring 202 is fixedly arranged at the top of the titanium basket 201 along the direction of the wall of the outer cylinder 3 to improve the conductivity of the titanium basket 201 of the lifting cathode 2. The copper ring 202 is connected to the cathode 2 above.

[0028] A base 6 is fixedly arranged below the outer cylinder 3. A fixing plate 601 is arranged between the outer cylinder 3 and the base 6. The outer cylinder 3 and the base 6 are fixed together through the fixing plate 601. Stay plates 602 are arranged around the lower end of the outer cylinder 3. The bottom of the stay plates 602 is fixed to the fixing plate 601 to prevent the fixing plate 601 from moving horizontally. Inlets 303 are arranged at the bottom of the outer cylinder 3 on both sides of the stay plates 602.

[0029] A housing 5 is arranged outside the outer cylinder 3. A cover plate 501 is arranged at the top of the housing 5. The cover plate 501 seals the tops of the inner cylinder 4, the outer cylinder 3 and the housing 5. External reinforcing ribs 301 are arranged equidistantly on the housing 5 to prevent the outer cylinder 3 from deforming. Internal reinforcing ribs 401 are arranged equidistantly outside the inner cylinder 4 to prevent the inner cylinder 4 from deforming due to the extrusion of the copper particles 203 on the inner cylinder 4; An observation window is arranged on the cover plate 501. A funnel 502 is arranged on the cover plate 501. The bottom opening of the funnel 502 is arranged between the inner cylinder 4 and the outer cylinder 3. The copper particles 203 are added between the inner cylinder 4 and the outer cylinder 3 through the funnel 502. An overflow port 503 is arranged on the outer cylinder 3 between the bottom opening of the funnel 502 and the copper particles 203. An overflow box 504 is arranged at the upper end of the housing 5. The overflow port 503 communicates with the overflow box 504. An outlet 505 is arranged at the bottom of the overflow box 504.

[0030] By arranging the overflow port 503 and the overflow box 504, the electroplating solution can overflow from the top of a copper dissolving tank of an iron ion-based copper plating system to the electroplating tank, and there is no need to additionally arrange a special pump for the copper dissolving tank.

[0031] Working steps: S1. Add the copper particles 203 between the inner cylinder 4 and the outer cylinder 3 through the funnel 502, and introduce the electroplating solution from the inlets 303 until the electroplating solution overflows from the overflow box 504.

[0032] S2. After the concentration of copper ions in the electroplating solution in the copper dissolving tank meets the requirements, continue to introduce the electroplating solution from the inlets 303, detect the concentration of copper ions in the overflow box 504, adjust the speed of introducing the electroplating solution at the inlets 303 so that the concentration of copper ions in the overflow box 504 is within the specified range, and transport the electroplating solution flowing out of the outlet 505 of the inner diameter of the overflow box 504 to the copper plating tank.

[0033] S3. Detect the concentration of ferric ions in the copper plating bath. When the concentration of ferric ions in the copper plating bath exceeds 1 g / L, energize the electrodes of the electrolytic regeneration copper dissolution bath, adjust the voltage and current density of the regeneration rectifier, and reduce the concentration of ferric ions in the electroplating solution in the copper dissolution bath until the concentration of ferric ions in the copper plating bath is less than 1 g / L.

[0034] The voltage of the regeneration rectifier externally connected to the cathode 2 and the anode 1 is 0 - 6 V, and the current density of the anode 1 is 5 - 10 ASD. In an electroplating solution in a copper dissolution bath based on an iron ion copper plating system, the Fe 3+ concentration < 1 g / L, and the concentration of CuSO 4 ·5H 2 O is 65 - 75 g / L.

[0035] Working principle: In the anode 1 region, due to the small area and high current density, the main reaction occurring at the anode 1 is the oxygen evolution reaction, and the solution exchange rate is slow. When the anode 1 is not energized, no reaction occurs. When energized, the main reactions are: 2OH - - 2e = O 2 + H 2 0, Fe 2+ - e = Fe 3 + ; Because the anode region is isolated by a dense anode cloth, the supply rate of Fe 2+ is slow, so the generation of Fe 3+ is small, and the diffusion rate into the solution is slow. Therefore, the concentration of Fe 3+ is confined in the anode region and less enters the electroplating solution.

[0036] In the cathode 2 region, since the copper particles 203 are connected to the cathode 2 and all the copper particles 203 are the cathode 2, and the surface area of the cathode 2 is huge, the average current density of the cathode 2 is very small, which enables Fe 3+ to be quickly reduced to Fe 2+ after contacting with the copper particles 203, realizing the regeneration of Fe 2+ , and reducing the concentration of Fe 3+ . At the same time, as the cathode 2, the copper particles 203 will reduce and deposit some copper ions on the copper particles 203 when energized, reducing the concentration of copper ions. When not energized, the copper particles 203 react with Fe 3+ to generate Cu 2+ , increasing the copper ion concentration. The reaction occurring at the cathode 2 when not energized is: 2Fe 3+ + Cu = + 2Fe 2+ . The reaction when energized is: the main reaction Fe 3+ + e = Fe 2+ , and a small amount of side reaction Cu 2+ + 2e + 2Cu.

[0037] In the copper dissolution tank of the present invention, the effect of "double low" concentrations of copper ions and ferric ions can be achieved. When not powered on, after ferric ions come into contact with copper particles 203, copper ions and ferrous ions are generated, increasing the concentration of copper ions and decreasing the concentration of ferric ions. When the concentration of copper ions reaches the specified range of the copper plating solution, the electroplating solution is pumped to the copper plating tank through the overflow port 503 and the outlet 505 via a pipeline. When the concentration of ferric ions is too high and affects the electroplating efficiency, power is applied to reduce ferric ions to ferrous ions, and the amount of ferric ions generated by the anode 1 is small and not easily diffused to the cathode 2 area. As a result, the concentration of ferric ions in the electroplating solution is reduced, the rising rate of copper ions is controlled, the electroplating efficiency is improved, and no waste of metallic copper is caused.

[0038] It should be noted that in this text, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0039] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A copper dissolving tank based on an iron ion copper plating system, comprising an outer cylinder (3) and a base (6), characterized in that: It also includes an inner tube (4) and an outer shell (5); A titanium rod (101) is provided through the center of the inner cylinder (4), the top end of the titanium rod (101) is connected to the anode (1), the inner cylinder (4) is arranged inside the outer cylinder (3), copper particles (203) are filled between the inner cylinder (4) and the outer cylinder (3), a titanium basket (201) is provided between the copper particles (203) and the inner wall of the outer cylinder (3), a copper ring (202) is fixedly provided on the top of the titanium basket (201) along the wall direction of the outer cylinder (3), and the top of the copper ring (202) is connected to the cathode (2); An outer shell (5) is provided outside the outer cylinder (3); an overflow box (504) is provided at the upper end of the outer shell (5); the overflow port (503) is opened and connected to the overflow box (504); and an outlet (505) is provided at the bottom of the overflow box (504).

2. A copper dissolving tank based on an iron ion copper plating system according to claim 1, characterized in that: The surface of the titanium rod (101) is coated with iridium dioxide, a plastic pipe (102) is disposed outside the titanium rod (101), and a filter cloth is wrapped outside the plastic pipe (102).

3. A copper dissolving tank based on an iron ion copper plating system according to claim 2, characterized in that: The plastic pipe (102) is a hard insulating material. The plastic pipe (102) has holes on all sides, the perforated area accounts for 70-80% of the side wall area of ​​the plastic pipe (102), and the bottom has no holes.

4. The copper dissolving tank based on the iron ion copper plating system according to claim 1, characterized in that: The titanium basket (201) is arranged around the inner side of the wall of the outer cylinder (3); one side of the titanium basket (201) is in contact with the copper particles (203), and the other side is in contact with the inner wall of the outer cylinder (3).

5. The copper dissolving tank based on the iron ion copper plating system according to claim 1, characterized in that: The inner cylinder (4) is evenly perforated on all sides, and the outside of the inner cylinder (4) is wrapped with filter cloth.

6. The copper dissolving tank based on the iron ion copper plating system according to claim 1, characterized in that: A base (6) is fixedly arranged below the outer cylinder (3), a fixed plate (601) is arranged between the outer cylinder (3) and the base (6), inclined plates (602) are arranged around the lower end of the outer cylinder (3), the bottom of the inclined plates (602) is fixed to the fixed plate (601), and inlets (303) are arranged at the bottom of the outer cylinder (3) on both sides of the inclined plates (602).

7. The copper dissolving tank based on the iron ion copper plating system according to claim 1, characterized in that: A cover plate (501) is provided on the top of the outer shell (5), and the cover plate (501) seals the tops of the inner cylinder (4), the outer cylinder (3) and the outer shell (5).

8. The copper dissolving tank based on the iron ion copper plating system according to claim 7, characterized in that: External reinforcing ribs (301) are arranged at equal intervals on the outer shell (5), and internal reinforcing ribs (401) are arranged at equal intervals on the outer side of the inner cylinder (4).

9. The copper dissolving tank based on the iron ion copper plating system according to claim 7, characterized in that: An observation window is provided on the cover plate (501), and a funnel (502) is provided on the cover plate (501). The bottom opening of the funnel (502) is provided between the inner cylinder (4) and the outer cylinder (3).

10. The copper dissolving tank based on the iron ion copper plating system according to claim 1, characterized in that: The voltage of the regeneration rectifier externally connected to the cathode (2) and the anode (1) is 0-6V, the current density of the anode (1) is 5-10ASD, and the Fe 3+ The concentration is <1g / L, and the concentration of CuSO4·5H2O is 65-75g / L.

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