A copper dissolution tank based on an iron ion copper plating system

Abstract

The present invention discloses a copper dissolution tank based on an iron ion copper plating system, belonging to the field of electrolytic cells for electrolytic plating. It includes an outer cylinder and a base, and also includes an inner cylinder and an outer shell. A titanium rod is disposed through the center of the inner cylinder, and the top of the titanium rod is connected to the anode. The inner cylinder is disposed within the outer cylinder, and copper particles are filled between the inner cylinder and the outer cylinder. A titanium basket is provided between the copper particles and the inner wall of the outer cylinder. A copper ring is fixedly provided at the top of the titanium basket along the direction of the outer cylinder wall, and the cathode is connected above the copper ring. By reducing the anode area and increasing the cathode area, the present invention reduces the average current density of the cathode, enabling the trivalent iron ions in contact with the surface of the copper particles to undergo a reduction reaction, reducing the concentration of trivalent iron ions, realizing the regeneration of divalent iron ions, and simultaneously reducing the reaction between metallic copper and trivalent iron, thereby controlling the dissolution rate of copper. When the concentration of copper ions in the electroplating solution is within the specified range of the copper plating solution, the concentration of trivalent iron ions is also within a lower range, improving the electroplating efficiency and controlling the additional consumption of copper.

Description

Technical Field

[0001] The present invention belongs to the field of electrolytic cells for electrolytic plating, and relates to electrolytic copper plating equipment for PCBs. Specifically, it relates to a copper dissolution 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 anodes and insoluble anodes. The soluble anode directly uses phosphor bronze balls as the anode. During electroplating, metallic copper dissolves to replenish copper ions, and during production, copper is replenished by adding phosphor bronze balls. This method requires regular cleaning due to the formation of anode films and anode slimes 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 slimes, does not require manual cleaning of the copper anode, and there is no waste, so it has high efficiency and good electroplating quality. The insoluble anode is divided into a ferric iron copper dissolution system and a copper oxide powder dissolution system according to the method of replenishing copper ions; in the copper oxide powder system, the control of copper ion concentration is relatively simple, and the reaction formula is: CuO + 2H + = Cu 2+ + H2O; however, copper oxide is prepared by oxidizing copper powder, increasing the processing cost of copper, the copper cost is relatively high, and 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 iron copper dissolution system generates copper ions through the reaction of ferric iron ions and copper, and the reaction formula is: 2Fe 3+ + Cu = Cu 2+ + 2Fe 2+ , and the anode does not produce an oxygen absorption reaction, and its comprehensive cost is the lowest. However, in the current copper dissolution tanks on the market (please refer to Figure 4 shown), the electroplating solution enters from the chemical solution inlet below the copper dissolution tank, and after fully contacting the metallic copper in the filter barrel, the ferric iron 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 in copper by this copper dissolution tank cannot effectively regulate the ferric iron ion concentration and copper ion concentration. When the number of copper particles is increased or (and) the flow rate is increased, the ferric iron ion concentration can be controlled at a relatively low 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 iron 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 passing efficiency, and at the same time, the concentration of ferric iron cannot be controlled within a lower range (such as less than 1 g / L).

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

[0006] The above 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. The additional device needs to control the ion concentration entering the electroplating tank. During the process of generating ferric 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 concentration of ferric iron ions will correspondingly increase, resulting in a reduction in electroplating efficiency by more than 10%. When controlling the reduction of ferric iron ion concentration, the concentration of copper ions 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 electroplated copper operation, the ferric 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:

[0009] 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 an outer shell.

[0010] 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.

[0011] An outer shell is arranged outside the outer cylinder, an overflow box is arranged at the upper end of the outer shell, an overflow port is opened and communicated to the overflow box, and an outlet is arranged at the bottom of the overflow box.

[0012] Further, 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.

[0013] Further, the plastic pipe is made of a rigid insulating material, with holes on all four sides and no holes at the bottom.

[0014] Further, the titanium basket is arranged along the inner side of the outer cylinder wall, with one side in contact with the copper grains and the other side in contact with the inner wall of the outer cylinder.

[0015] Further, the inner cylinder is evenly drilled on all four sides, and a filter cloth is wrapped outside the inner cylinder.

[0016] Further, a base is fixedly arranged below the outer cylinder, a fixing plate is arranged between the outer cylinder and the base, stay plates are arranged around the lower end of the outer cylinder, the bottom of the stay plates is fixed to the fixing plate, and inlets are arranged at the bottom of the outer cylinder on both sides of the stay plates.

[0017] Further, 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.

[0018] Further, external reinforcing ribs are arranged at equal intervals on the outer shell, and internal reinforcing ribs are arranged at equal intervals on the outer side of the inner cylinder.

[0019] Further, an observation window is arranged on the cover plate, a funnel is arranged on the cover plate, and the bottom opening of the funnel is arranged between the inner cylinder and the outer cylinder.

[0020] Further, 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, and the Fe 3+ concentration in the electroplating solution in the electrolytic regeneration copper dissolution tank is < 1 g / L, and the concentration of CuSO4·5H2O is 65 - 75 g / L.

[0021] Advantages of the present invention:

[0022] 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 grains), the average current density of the cathode is reduced, enabling the ferric ions in contact with the surface of the copper grains 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. This enables the ferric ion concentration to be in a lower range when the copper ion concentration in the electroplating solution is within the specified range of the copper plating solution, improving the electroplating efficiency and controlling the additional consumption of copper. Description of the Drawings

[0023] The following further describes the present invention with reference to the drawings.

[0024] Figure 1 is a schematic cross-sectional view of a copper dissolution tank based on an iron ion copper plating system of the present invention;

[0025] Figure 2 is Figure 1 The enlarged view of part A in

[0026] Figure 3 is Figure 1 The enlarged view of part B in

[0027] Figure 4 is the schematic cross-sectional view of the prior art copper melting tank;

[0028] In the figure: 1. Anode; 101. Titanium rod; 102. Plastic pipe; 2. Cathode; 201. Titanium basket; 202. Copper ring; 203. Copper granule; 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 shell. Specific embodiments

[0029] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0030] Embodiment

[0031] Please refer to Figure 1 As shown, a copper melting 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.

[0032] Please refer to Figure 1 and Figure 2 As shown, a titanium rod 101 is centrally penetrated through 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.

[0033] Please refer to Figures 1-3As shown in the figure, 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%. The outer part of the inner cylinder 4 is wrapped with filter cloth to prevent the copper particles 203 from entering the inner cylinder 4. The outer cylinder 3 is made of NPP translucent material.

[0034] 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 barrel 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 barrel 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.

[0035] 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. Diagonal bracing plates 602 are arranged around the lower end of the outer cylinder 3. The bottom of the diagonal bracing 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 diagonal bracing plates 602.

[0036] 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.

[0037] 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 without additionally arranging a special pump for the copper dissolving tank.

[0038] Working steps:

[0039] 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 inlet 303 until the electroplating solution overflows from the overflow box 504.

[0040] S2. After the copper ion concentration in the electroplating solution in the copper dissolution tank meets the requirements, continue to introduce the electroplating solution from the inlet 303, detect the copper ion concentration in the overflow box 504, adjust the speed of introducing the electroplating solution at the inlet 303 so that the copper ion concentration in the overflow box 504 is within the specified range, and transport the electroplating solution flowing out from the outlet 505 of the inner diameter of the overflow box 504 to the copper plating tank.

[0041] S3. Detect the ferric ion concentration in the copper plating tank. When the ferric ion concentration in the copper plating tank exceeds 1 g / L, energize the electrodes of the electrolytic regeneration copper dissolution tank, adjust the voltage and current density of the regeneration rectifier, and reduce the ferric ion concentration in the electroplating solution in the copper dissolution tank until the ferric ion concentration in the copper plating tank is less than 1 g / L.

[0042] 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 the electroplating solution in the copper dissolution tank based on the iron ion copper plating system, the Fe 3+ concentration < 1 g / L, and the concentration of CuSO4·5H2O is 65 - 75 g / L.

[0043] Working principle:

[0044] In the anode 1 area, 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 relatively slow. When the anode 1 is not energized, no reaction occurs. When energized, the main reactions are: 2OH - - 2e = O2 + H20, Fe 2+ - e = Fe 3 + ; Because the anode area is isolated by the dense anode cloth, the supply rate of Fe 2+ is slow, so less Fe 3+ is generated, and the diffusion rate into the solution is slow. Therefore, in the anode area, the Fe 3+ concentration is confined to the anode area and less enters the electroplating solution.

[0045] In the cathode 2 area, 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 extremely large, the average current density of the cathode 2 is very small, so that Fe 3+ is quickly reduced to Fe 2+ after contacting with the copper particles 203, realizing the regeneration of Fe 2+ , and reducing the Fe 3+ concentration. At the same time, as the cathode 2, the copper particles 203 will cause some copper ions to be reduced and deposited on the copper particles 203 when energized, reducing the copper ion concentration. When not energized, the copper particles 203 and Fe 3+ react to generate Cu 2+ , increasing the copper ion concentration. The reaction occurring at the cathode 2 when not energized is: 2Fe 3+ + Cu = + 2Fe2+ When powered on, the reaction is: the main reaction Fe 3+ + e = Fe 2+ , and a small amount of side reaction Cu 2+ + 2e + 2Cu.

[0046] 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 contact the copper particles 203, copper ions and ferrous ions are generated, increasing the copper ion concentration and decreasing the ferric ion concentration. When the copper ion concentration 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 ferric ion concentration is too high and affects the electroplating efficiency, power is applied to reduce the ferric ions to ferrous ions. Moreover, the amount of ferric ions generated by the anode 1 is small and it is not easy to diffuse into the cathode 2 area. As a result, the ferric ion concentration in the electroplating solution is reduced, the rising speed of copper ions is controlled, the electroplating efficiency is improved, and there is no waste of metallic copper.

[0047] It should be noted that in this article, 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 further includes elements inherent to such process, method, article or device.

[0048] 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 principles 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 dissolution 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 cylinder (4) and an outer shell (5); A titanium rod (101) runs through the center of the inner cylinder (4). The top of the titanium rod (101) is connected to the anode (1). The inner cylinder (4) is arranged inside the outer cylinder (3). Copper grains (203) are filled between the inner cylinder (4) and the outer cylinder (3). A titanium basket (201) is arranged between the copper grains (203) and 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 outer wall of the outer cylinder (3). The cathode (2) is connected above the copper ring (202); An outer shell (5) is arranged outside the outer cylinder (3). An overflow box (504) is arranged at the upper end of the outer shell (5). An overflow port (503) is opened and communicated with the overflow box (504). An outlet (505) is arranged at the bottom of the overflow box (504); The voltage of the external regenerative rectifier connected to the cathode (2) and the anode (1) is 0 - 6V, the current density of the anode (1) is 5 - 10 ASD, and the Fe 3+ concentration in the electroplating solution in the electrolytic regeneration copper dissolution tank is < 1 g / L, and the concentration of CuSO4·5H2O is 65 - 75 g / L; The area ratio of the cathode (2) to the anode (1) exceeds 1000:1; Working steps: S1. Add copper grains (203) between the inner cylinder (4) and the outer cylinder (3) through a funnel, and introduce electroplating solution from the inlet until the electroplating solution overflows from the overflow box (504); S2. After the concentration of copper ions in the electroplating solution in the copper dissolution tank meets the requirements, continue to introduce electroplating solution from the inlet, detect the concentration of copper ions in the overflow box (504), adjust the speed of the electroplating solution introduced from the inlet, 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; S3. Detect the concentration of ferric ions in the copper plating tank. When the concentration of ferric ions in the copper plating tank exceeds 1 g / L, energize the electrodes of the electrolytic regeneration copper dissolution tank, 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 tank until the concentration of ferric ions in the copper plating tank is less than 1 g / L.

2. The copper dissolution tank based on the 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 sleeved outside the titanium rod (101), and a filter cloth is wrapped outside the plastic pipe (102).

3. A copper dissolution tank based on an iron ion copper plating system according to claim 2, characterized in that, The plastic pipe (102) is made of a hard insulating material. The plastic pipe (102) is perforated around. The perforated area accounts for 70 - 80% of the side wall area of the plastic pipe (102), and there are no holes at the bottom.

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

5. A copper dissolution tank based on an iron ion copper plating system according to claim 1, characterized in that, The inner cylinder (4) is evenly perforated around, and a filter cloth is wrapped outside the inner cylinder (4).

6. The copper dissolution tank based on an iron ion copper plating system according to claim 1, characterized in that, 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). Diagonal bracing plates (602) are arranged around the lower end of the outer cylinder (3). The bottom of the diagonal bracing plates (602) is fixed to the fixing plate (601). Inlets (303) are arranged at the bottom of the outer cylinder (3) on both sides of the diagonal bracing plates (602).

7. A copper dissolution tank based on an iron ion copper plating system according to claim 1, wherein, A cover plate (501) is arranged at 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. A copper dissolution tank based on an 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 outside the inner cylinder (4).

9. A copper dissolution tank based on an 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 arranged between the inner cylinder (4) and the outer cylinder (3).

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