Preparation method and system for low ESR tantalum capacitor anodes

Abstract

This invention belongs to the field of tantalum anode technology, specifically relating to a method and system for preparing a low-ESR tantalum capacitor anode. The method includes: during the energizing process, intermittently applying high-frequency pressure waves to the energizing solution to ensure uniform penetration of the energizing solution into the interior of the tantalum anode, improving the uniformity of the concentration of the energizing solution inside and outside the tantalum anode, making the current distribution more uniform, ensuring a consistent oxide film growth rate, and reducing ESR. The temperature of the energizing solution is 70℃-90℃, and the high-frequency pressure waves are applied every 10min-30min, each lasting 1min-5min, until the energizing process is completed. During the manganese impregnation process, intermittently applying low-frequency pressure waves to the manganese impregnation solution to increase the diffusion rate of manganese nitrate ions, allowing the manganese nitrate ions to penetrate into the pores of the tantalum anode more quickly, resulting in uniform deposition of the MnO2 layer over a wider area. This avoids the problem of an excessively thin or void MnO2 layer due to poor permeability, further reducing ESR. The temperature of the manganese impregnation solution is 35℃-45℃, and the low-frequency pressure waves are applied every 2min-4min, each lasting 20s-40s, until the manganese impregnation process is completed.

Description

Technical Field

[0001] This invention belongs to the field of tantalum anode technology, specifically relating to a method and system for preparing a low-ESR tantalum capacitor anode. Background Technology

[0002] Tantalum capacitors are high-performance electrolytic capacitors with tantalum metal as the core material. They are characterized by small size, large capacitance, and high reliability, and are widely used in electronic devices. Their manufacturing process includes tantalum powder pressing, high-temperature sintering, energizing (anodic oxidation), manganese impregnation (coating), graphite and silver coating, lead soldering, and encapsulation.

[0003] However, when energizing some large-volume high-energy tantalum anodes or high-specific-capacitance tantalum anodes, uneven penetration can lead to inconsistent solution concentrations, resulting in uneven current distribution, inconsistent oxide film growth rates, and oxygen bubbles generated by the oxygen evolution reaction adhering to the surface and interior of the tantalum anode, hindering uniform Ta2O5 deposition and causing uneven oxide film thickness. This leads to increased leakage current and ESR. In the manganese immersion process, due to the poor permeability of manganese nitrate solution, the MnO2 layer inside the porous tantalum anode is easily too thin or contains voids, failing to completely cover the Ta2O5 dielectric layer surface, also causing increased ESR. Furthermore, repeated manganese immersion can cause the MnO2 layer on the tantalum anode surface to become too thick, making it prone to cracking or detachment under stress during thermal decomposition, further increasing ESR.

[0004] In existing technologies, vacuum impregnation devices and staged pressurization techniques are used to improve the impregnation effect of solutions. However, these methods suffer from problems such as complex equipment, high cost, and long processing time, and they cannot completely solve the problem of incomplete solution impregnation. Summary of the Invention

[0005] In view of this, the present invention provides a method and system for preparing a low-ESR tantalum capacitor anode, in order to solve the technical problem of high ESR in tantalum anodes prepared by energy conversion and manganese impregnation in the prior art.

[0006] To achieve the above objectives, this application adopts the following approach: A method for preparing a low-ESR tantalum capacitor anode involves intermittently applying high-frequency pressure waves to the energizing liquid during the energizing process. This allows the energizing liquid to penetrate uniformly into the interior of the tantalum anode, improving the uniformity of the energizing liquid concentration inside and outside the tantalum anode, resulting in a more uniform current distribution, consistent oxide film growth rate, and reduced ESR. The temperature of the energizing liquid is 70℃-90℃, and the high-frequency pressure waves are applied every 10-30 minutes, each lasting 1-5 minutes, until the energizing process is completed. During the manganese immersion process, low-frequency pressure waves are intermittently applied to the manganese immersion solution to increase the diffusion rate of manganese nitrate ions. This allows the manganese nitrate ions to penetrate into the pores of the tantalum anode more quickly, resulting in uniform deposition of the MnO2 layer over a wider area. This avoids the problem of an excessively thin or void MnO2 layer due to poor permeability, thereby reducing ESR. The temperature of the manganese immersion solution is 35℃-45℃, and the low-frequency pressure waves are applied every 2-4 minutes, each lasting 20-40 seconds, until the manganese immersion process is completed.

[0007] Preferably, the enabling process specifically includes the following steps: S11. The energy-generating solution is a phosphoric acid solution or a mixed solution of phosphoric acid and ethylene glycol. The tantalum anode is immersed in the mixed solution, and a DC voltage is applied to generate a Ta2O5 dielectric layer. S12. Heat the mixed solution to 70℃-90℃; S13. When energizing the tantalum anode begins, a high-frequency pressure wave of 20KHz-100KHz is intermittently applied to the mixed solution, and the wave is turned on once every 10min-30min, with each turn lasting 1min-5min.

[0008] Preferably, the manganese immersion process specifically includes the following steps: S21. The tantalum anode obtained after energy conversion is boiled and dried with deionized water; S22. The manganese immersion solution is a manganese nitrate solution. The tantalum anode is immersed in the manganese nitrate solution to undergo thermal decomposition and generate a MnO2 layer. S23. Maintain the temperature of the manganese nitrate solution at 35℃-45℃; S24. When the tantalum anode is immersed in manganese, a low-frequency pressure wave of 10KHz-40KHz is applied to the manganese nitrate solution, once every 2min-4min, and each application lasts for 20s-40s.

[0009] Preferably, the manganese immersion process includes 2 to 4 manganese immersion steps, and as the number of manganese immersion steps increases, the frequency and application time of the low-frequency pressure wave decrease sequentially.

[0010] Preferably, when the manganese immersion process includes three manganese immersion steps, in the first manganese immersion, the concentration of the manganese nitrate solution is 20%, the frequency of the low-frequency pressure wave is 35KHz, and it is applied once every 2 minutes for 30 seconds each time.

[0011] Preferably, when the manganese immersion process includes three manganese immersion steps, in the second manganese immersion, the concentration of the manganese nitrate solution is 30%, the frequency of the low-frequency pressure wave is 25KHz, and it is applied once every 2 minutes for 25 seconds each time.

[0012] Preferably, when the manganese immersion process includes three manganese immersion steps, in the third manganese immersion, the concentration of the manganese nitrate solution is 30%, the frequency of the low-frequency pressure wave is 15KHz, and it is applied once every 2 minutes for 20 seconds each time.

[0013] A system for preparing a low-ESR tantalum capacitor anode includes an energizing device and a manganese impregnation device. The energizing device is equipped with a permeation defoaming component, which can generate high-frequency pressure waves of 20KHz-100KHz. The manganese impregnation device is equipped with a cavitation shielding component, which can generate low-frequency pressure waves of 10KHz-40KHz.

[0014] Preferably, the energy-enhancing device specifically includes a first metal sheet, a circulating water pump, an energy-enhancing tank, an overflow plate, and an energy-enhancing DC power supply. The energy-enhancing tank is used to hold the energy-enhancing solution. The first metal sheet is disposed on the opening of the energy-enhancing tank through an insulating gasket. A plurality of first tantalum wires are spaced apart on the lower surface of the first metal sheet. The tantalum anode to be energized is disposed on the first tantalum wires. The positive terminal of the energy-enhancing DC power supply is connected to the first metal sheet, and the negative terminal is connected to the energy-enhancing tank. The overflow plate is vertically disposed in the energy-enhancing tank, forming a replenishment chamber between itself and one side of the energy-enhancing tank. The height of the overflow plate is higher than the height of the tantalum anode to ensure the level of the energy-enhancing solution, so that the solution just covers the upper part of the tantalum anode. The overflowing solution flows to the replenishment chamber. The circulating water pump is connected to the replenishment chamber and the energy-enhancing tank to pump the solution in the replenishment chamber back into the energy-enhancing tank to achieve solution circulation. A first heater is disposed at the lower part of the energy-enhancing tank, and the permeation defoaming assembly is disposed on the outer wall of the energy-enhancing tank.

[0015] Preferably, the manganese immersion device specifically includes a second metal sheet and a conical manganese immersion tank. The conical manganese immersion tank is used to hold the manganese immersion solution. The second metal sheet is disposed at the opening of the conical manganese immersion tank. A plurality of second tantalum wires are disposed at intervals on the lower surface of the second metal sheet. The tantalum anode to be immersed in manganese is disposed on the second tantalum wires. The conical part of the conical manganese immersion tank is provided with a discharge port. The lower part of the conical manganese immersion tank is provided with a second heater. The air-raid shelter assembly is disposed on the outer wall of the conical manganese immersion tank.

[0016] In the above-mentioned method and system for preparing the low-ESR tantalum capacitor anode, during the energizing process, the 20kHz-100kHz high-frequency pressure wave generated by the defoaming component 7 induces the generation, expansion, and violent rupture of microbubbles in the energizing solution. The jet generated by the ruptured bubbles impacts the surface and pores of the tantalum anode 1, effectively preventing gas retention. Simultaneously, it improves the permeability of phosphate ions in the solution, resulting in a more uniform current density distribution and a more consistent oxide film growth rate. Furthermore, the intermittent use of high-frequency pressure waves allows for more frequent stirring and venting of the solution, which helps maintain the homogeneity and stability of the solution and reduces oxide film formation. In cases of uneven thickness, leakage current and ESR are reduced. When using the manganese immersion device provided by this invention for manganese immersion, the 10KHz-40KHz low-frequency pressure wave generated by the anti-cavitation component 15, the micro-jet and shock wave generated by the cavitation effect can increase the turbulence of the solution, reduce the concentration gradient in the solution, and increase the diffusion rate of manganese nitrate ions. This allows manganese nitrate ions to penetrate into the pores of the tantalum anode 1 more quickly, so that the MnO2 layer after thermal decomposition is uniformly deposited in a wider area. This avoids the problem of the MnO2 layer being too thin or having voids due to poor permeability, thereby reducing ESR and improving the performance of the tantalum capacitor.

[0017] In addition, the high-frequency pressure wave is used intermittently during the energizing time, which can achieve a better energizing effect without the need for a staged pressure boosting energizing process, avoiding the problem of long energizing time in multiple stages and improving efficiency; the low-frequency pressure wave is used intermittently during the manganese immersion time, which can reduce the number of manganese immersions, thereby avoiding problems such as excessive MnO2 layer thickness, cracking or peeling during thermal decomposition caused by multiple manganese immersions, thus improving the quality and performance of the product. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the energy-generating device in this invention.

[0019] Figure 2 This is a schematic diagram of the manganese leaching device in this invention.

[0020] In the figure, 1 is a tantalum anode, 2 is a tantalum wire, 3 is a first metal sheet, 4 is an insulating gasket, 5 is a replenishment tank, 6 is a circulating water pump, 7 is a permeation defoaming assembly, 8 is a first heater, 9 is an energizing tank, 10 is an overflow plate, 13 is a second metal sheet, 14 is a manganese immersion tank, 15 is an air-raid shelter assembly, 16 is a discharge port, 17 is a second heater, and 18 is an energizing DC power supply. Detailed Implementation

[0021] To facilitate understanding of this application, a more comprehensive description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are also given. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to enable a more thorough and complete understanding of the disclosure of this application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0023] This application provides a method for preparing the anode of a low-ESR tantalum capacitor, comprising the following steps: During the energizing process, high-frequency pressure waves are intermittently applied to the energizing solution to ensure uniform penetration of the energizing solution into the interior of the tantalum anode, thereby improving the uniformity of the concentration of the energizing solution inside and outside the tantalum anode, making the current distribution more uniform, the oxide film growth rate consistent, and reducing ESR. The temperature of the energizing solution is 70℃-90℃, and the high-frequency pressure waves are applied once every 10min-30min, each time lasting 1min-5min, until the energizing process ends. During the manganese immersion process, low-frequency pressure waves are intermittently applied to the manganese immersion solution to increase the diffusion rate of manganese nitrate ions. This allows the manganese nitrate ions to penetrate more quickly into the pores of the tantalum anode, resulting in a more uniform deposition of the MnO2 layer over a wider area. This avoids the problem of an excessively thin or void MnO2 layer due to poor permeability, thus reducing ESR. The temperature of the manganese immersion solution is 35℃-45℃. The low-frequency pressure waves are applied every 2-4 minutes, each lasting 20-40 seconds, until the manganese immersion process is completed. The high-frequency and low-frequency pressure waves can be generated using a shock wave generator, a pulsed pneumatic generator, a cavitation jet generator, etc. In this embodiment, an ultrasonic generator is preferred.

[0024] In the preparation process, the tantalum anode 1 is first subjected to high-temperature vacuum sintering to obtain the tantalum anode 1 of the required specifications. Then, it is energized using an energizing device. During energizing, the energizing solution is generally a phosphoric acid solution or a mixture of phosphoric acid and ethylene glycol. The tantalum anode 1 is immersed in the energizing solution and heated. At the same time, a high-frequency pressure wave is applied to the energizing solution, which is turned on every 10-30 minutes, and the time of each turn is 1-5 minutes, until the energizing process is completed. After the energizing process is completed, the tantalum anode 1 is pretreated by cleaning, and then the manganese nitrate solution required for the manganese immersion process is prepared and placed in the manganese immersion device. The tantalum anode 1 is immersed in the manganese nitrate solution, and the heating device required for the manganese immersion process is turned on. The relevant parameters of the manganese immersion process (temperature 35℃-45℃) are controlled. At the same time, a low-frequency pressure wave is applied to the manganese nitrate solution, which is turned on every 2-4 minutes, and the time of each turn is 20-40 seconds, until the manganese immersion process is completed.

[0025] During the energizing process, the 20kHz-100kHz high-frequency pressure wave generated by the defoaming component 7 induces the generation, expansion, and violent rupture of microbubbles in the energizing solution. The jet generated by the ruptured bubbles impacts the surface and pores of the tantalum anode 1, effectively preventing gas retention. Simultaneously, it improves the permeability of phosphate ions in the solution, resulting in a more uniform current density distribution and a more consistent oxide film growth rate. Furthermore, the intermittent use of high-frequency pressure waves allows for more frequent stirring and venting of the solution, which helps maintain the uniformity and stability of the solution, reduces uneven oxide film thickness, and minimizes leakage. Current and ESR; When using the manganese immersion device provided by this invention for manganese immersion, the 10KHz-40KHz low-frequency pressure wave generated by the anti-cavitation component 15, the micro-jet and shock wave generated by the cavitation effect can increase the turbulence of the solution, reduce the concentration gradient in the solution, and increase the diffusion rate of manganese nitrate ions, so that manganese nitrate ions can penetrate into the pores of the tantalum anode 1 more quickly, so that the MnO2 layer after thermal decomposition can be uniformly deposited in a wider area, avoiding the problem of the MnO2 layer being too thin or void due to poor permeability, thereby reducing ESR and improving the performance of the tantalum capacitor.

[0026] In addition, the high-frequency pressure wave is used intermittently during the energizing time, which can achieve a better energizing effect without the need for a staged pressure boosting energizing process, avoiding the problem of long energizing time in multiple stages and improving efficiency; the low-frequency pressure wave is used intermittently during the manganese immersion time, which can reduce the number of manganese immersions, thereby avoiding problems such as excessive MnO2 layer thickness, cracking or peeling during thermal decomposition caused by multiple manganese immersions, thus improving the quality and performance of the product.

[0027] Specifically, the enabling process includes the following steps: S11. The energy-generating solution is a phosphoric acid solution or a mixed solution of phosphoric acid and ethylene glycol. The tantalum anode is immersed in the mixed solution, and a DC voltage is applied to generate a Ta2O5 dielectric layer. S12. Heat the mixed solution to 70℃-90℃; S13. When energizing the tantalum anode begins, a high-frequency pressure wave of 20KHz-100KHz is intermittently applied to the mixed solution, and the wave is turned on once every 10min-30min, with each turn lasting 1min-5min.

[0028] In the preparation process, specifically, the tantalum anode 1, which has undergone pretreatment (such as high-temperature vacuum sintering after pre-embedding tantalum powder and tantalum wire 2), is carefully immersed in the mixed solution to ensure that the tantalum anode 1 is completely covered by the solution. After the tantalum anode 1 is immersed in the mixed solution, a DC power supply is connected, and a DC voltage is applied to the tantalum anode 1. Under the action of the electric field, phosphate ions in the solution migrate to the surface of the tantalum anode 1 and react chemically with the tantalum anode 1, gradually forming a Ta2O5 dielectric layer on the surface and inside the pores of the tantalum anode 1. The solution temperature in the container containing the tantalum anode 1 and the mixed solution is heated to 70℃-90℃ using a heating device (such as a heater) to improve the fluidity of the solution, reduce the surface tension of the solution, and help the solution better penetrate into the porous structure of the tantalum anode 1. After the tantalum anode 1 is energized, a high-frequency pressure wave of 20KHz-100KHz is applied every 10min-30min, with each application lasting 1min-5min. When high-frequency pressure waves propagate in the mixed solution, they can impact the surface and pores of tantalum anode 1, expelling trapped gas and ensuring uniform growth of the Ta2O5 dielectric layer. By improving solution permeability and preventing gas retention, phosphate ions in the solution can react more uniformly with tantalum anode 1, thereby ensuring uniform deposition of the Ta2O5 dielectric layer on the surface and within the pores of tantalum anode 1, avoiding defects such as voids and cracks.

[0029] With improved solution permeability and the resolution of gas retention issues, the Ta2O5 dielectric layer has a more uniform thickness and higher density, reducing defects in the dielectric layer and thus improving its quality. Furthermore, the uniform and dense Ta2O5 dielectric layer can reduce the resistance to electron transport within the dielectric layer, lowering the equivalent series resistance (ESR) of the tantalum capacitor and improving its performance.

[0030] Specifically, the manganese immersion process includes the following steps: S21. The tantalum anode obtained after energy conversion is boiled and dried with deionized water; S22. The manganese immersion solution is a manganese nitrate solution. The tantalum anode is immersed in the manganese nitrate solution to undergo thermal decomposition and generate a MnO2 layer. S23. Maintain the temperature of the manganese nitrate solution at 35℃-45℃; S24. When the tantalum anode is immersed in manganese, a low-frequency pressure wave of 10KHz-40KHz is applied to the manganese nitrate solution, and the wave is turned on once every 2min-4min, with each turn lasting 20s-40s.

[0031] During operation, the tantalum anode 1 obtained through the energy-enhancing process is placed in deionized water for boiling and washing. During the boiling and washing process, a certain temperature and time are maintained (the specific temperature can be set according to the actual situation, with a temperature of 90℃-100℃ and a boiling and washing time of 15min-30min) to remove the residual energy-enhancing solution and other impurities on the surface of the tantalum anode 1. After boiling and washing, the tantalum anode 1 is taken out and placed in a drying equipment for drying treatment (drying temperature of 110℃-120℃ and drying time of 20min-40min) to remove surface moisture and ensure that the tantalum anode 1 is dry. Prepare a manganese nitrate solution as the solution for the manganese immersion process. Carefully immerse the dried tantalum anode 1 into the manganese nitrate solution, ensuring that the tantalum anode 1 is completely covered by the solution. Use a heating device or a constant temperature water bath to maintain the solution temperature in the container containing the tantalum anode 1 and the manganese nitrate solution at 35℃-45℃. When the manganese immersion of the tantalum anode 1 begins, apply a low-frequency pressure wave of 10KHz-40KHz to the solution, once every 2min-4min, with each application lasting 20s-40s. During the manganese immersion process, manganese ions in the manganese nitrate solution will gradually adsorb onto the surface of the tantalum anode 1, and then undergo a thermal decomposition reaction at a certain temperature to generate a MnO2 layer.

[0032] Due to the suitable solution temperature and the effect of low-frequency pressure waves, the MnO2 layer has a more uniform thickness and higher density, reducing defects in the dielectric layer and thus improving the quality of the MnO2 layer. The uniform and dense MnO2 layer can reduce the resistance to electron transport in the electrolyte, lower the equivalent series resistance (ESR) of the tantalum capacitor, and improve the performance of the tantalum capacitor.

[0033] Preferably, the manganese immersion process includes 2 to 4 manganese immersion steps, and as the number of manganese immersion steps increases, the frequency and application time of the low-frequency pressure wave decrease sequentially.

[0034] The tantalum anode 1 has a porous structure. Multiple manganese immersions allow the manganese nitrate solution to gradually penetrate into the deeper pores of the tantalum anode 1, enabling the MnO2 layer to grow uniformly inside and on the surface of the tantalum anode 1, filling more pores and increasing the density of the MnO2 layer. During each manganese immersion process, a new MnO2 layer can grow on the surface of the previously formed MnO2 layer, repairing any minor defects that may have existed in the previous layer, such as voids and cracks, thereby improving the overall quality of the MnO2 layer.

[0035] In the initial stage of manganese immersion, using a higher low-frequency pressure wave and a longer application time can generate a strong cavitation effect and mechanical stirring. Intense stirring can quickly break the surface tension of the solution, allowing the manganese nitrate solution to rapidly penetrate into the pores of the tantalum anode 1, while simultaneously expelling gas from the pores, creating favorable conditions for the uniform deposition of MnO2. As the number of manganese immersion cycles increases, the low-frequency pressure wave and application time are appropriately reduced. At this point, the main function of the low-frequency pressure wave is to optimize the growth process of the MnO2 layer, enabling the MnO2 crystals to grow more uniformly on the existing foundation, reducing grain agglomeration and uneven growth.

[0036] Preferably, when the manganese immersion process includes three manganese immersion steps, in the first manganese immersion, the concentration of the manganese nitrate solution is 20%, the frequency of the low-frequency pressure wave is 35 kHz, and it is applied once every 2 minutes for 30 seconds each time; in the second manganese immersion, the concentration of the manganese nitrate solution is 30%, the frequency of the low-frequency pressure wave is 25 kHz, and it is applied once every 2 minutes for 25 seconds each time; in the third manganese immersion, the concentration of the manganese nitrate solution is 30%, the frequency of the low-frequency pressure wave is 15 kHz, and it is applied once every 2 minutes for 20 seconds each time.

[0037] For further details, please refer to Figure 1 and Figure 2 This application also provides a system for preparing a low-ESR tantalum capacitor anode, including an energizing device and a manganese impregnation device. The energizing device is equipped with a permeation defoaming component 7, which can generate high-frequency pressure waves of 20kHz-100kHz. The manganese impregnation device is equipped with a cavitation-proof component 15, which can generate low-frequency pressure waves of 10kHz-40kHz. The defoaming component 7 and the cavitation-proof component 15 can be shock wave generators, pulse pneumatic generators, cavitation jet generators, etc. In this embodiment, an ultrasonic generator is preferred.

[0038] Specifically, the energy-enhancing device includes a first metal sheet 3, a circulating water pump 6, an energy-enhancing tank 9, an overflow plate 10, and an energy-enhancing DC power supply 18. The energy-enhancing tank 9 is used to hold the energy-enhancing solution. The first metal sheet 3 is disposed on the opening of the energy-enhancing tank 9 through an insulating gasket 4. A plurality of first tantalum wires 2 are spaced apart on the lower surface of the first metal sheet 3. The tantalum anode 1 to be energized is disposed on the first tantalum wires 2. The positive terminal of the energy-enhancing DC power supply 18 is connected to the first metal sheet 3, and the negative terminal is connected to the energy-enhancing tank 9. The overflow plate 10 is vertically disposed on the first metal sheet 3. Inside the energizing tank 9, a replenishment tank 5 is formed between the tank and one side. The overflow plate 10 is higher than the height of the tantalum anode 1 to ensure the energizing solution level, so that the solution just covers the upper part of the tantalum anode 1. The overflowing solution flows to the replenishment tank 5. The circulating water pump 6 is connected to the replenishment tank 5 and the energizing tank 9 to pump the solution in the replenishment tank 5 back into the energizing tank 9 to achieve solution circulation. A first heater 8 is provided at the lower part of the energizing tank 9, and a permeation defoaming component 7 is provided on the outer wall of the energizing tank 9.

[0039] Specifically, the manganese immersion device includes a second metal sheet 13 and a conical manganese immersion tank 14. The conical manganese immersion tank 14 is used to hold the manganese immersion solution. The second metal sheet 13 is disposed on the opening of the conical manganese immersion tank 14. A plurality of second tantalum wires 2 are disposed at intervals on the lower surface of the second metal sheet 13. The tantalum anode 1 to be immersed in manganese is disposed on the second tantalum wires 2. The conical part of the conical manganese immersion tank 14 is provided with a discharge port 16. The lower part of the conical manganese immersion tank 14 is provided with a second heater 17. An air-raid shelter assembly 15 is provided on the outer wall of the conical manganese immersion tank 14.

[0040] The tantalum anode 1, pre-embedded with tantalum powder and tantalum wire 2, is subjected to high-temperature vacuum sintering. Multiple tantalum anodes 1 obtained after sintering are then evenly spot-welded onto a first metal sheet 3. The first metal sheet 3 is placed on an energy-enhancing tank 9 and insulated by an insulating pad 4. The energy-enhancing tank 9 contains a 0.01%-0.5% phosphoric acid solution or a mixture of phosphoric acid and ethylene glycol. An overflow plate 10 in the energy-enhancing tank 9 ensures the energy-enhancing solution level is maintained, just covering the top of the tantalum anode 1. The overflowing solution flows to a replenishment tank 5, and a circulating water pump 6 pumps the solution from the replenishment tank 5 back into the energy-enhancing tank 9, thus circulating the solution. Then, the second heater 17 is activated to heat the solution in the energy-enhancing tank 9 to 70℃-90℃. The positive terminal of the DC power supply 18 is connected to a metal sheet, and the negative terminal of the DC power supply 18 is connected to the charging tank 9 to ensure that it is energized. When the charging of the tantalum anode 1 begins, the defoaming component 7 is turned on every 10-30 minutes, with each turn lasting 1-5 minutes, to generate a high-frequency pressure wave. The tantalum anode 1 obtained after the charging process is cleaned and dried to remove residual charging solution and other impurities from the surface of the tantalum anode 1. Manganese nitrate solution is added to the manganese immersion tank 14. The tantalum anode 1 is evenly spot-welded onto the second metal sheet 13. The second metal sheet 13 is placed on the manganese immersion tank 14, so that the dried tantalum anode 1 is immersed in the manganese nitrate solution, ensuring that the tantalum anode 1 is completely covered by the solution. The second heater 17 is turned on to maintain the solution temperature in the manganese immersion tank 14 at 35℃-45℃. When the manganese immersion of the tantalum anode 1 begins, the air-raid shelter component 15 is activated to generate a low-frequency pressure wave. It is activated once every 2min-4min, and each activation lasts for 20s-40s. During the manganese immersion process, manganese ions in the manganese nitrate solution will gradually adsorb onto the surface of the tantalum anode 1, and then undergo a thermal decomposition reaction at a certain temperature to generate a MnO2 layer.

[0041] When using the energy-generating device provided by this invention, the 20kHz-100kHz high-frequency pressure wave generated by the permeation and defoaming component 7 induces the generation, expansion, and violent rupture of microbubbles in the energy-generating liquid. The jet generated by the rupture of bubbles impacts the surface and pores of the tantalum anode 1, effectively preventing gas retention. Simultaneously, it improves the permeability of phosphate ions in the solution, resulting in a more uniform current density distribution and a more consistent oxide film growth rate. Furthermore, the intermittent use of high-frequency pressure waves allows for more frequent stirring and venting of the solution, which helps maintain the uniformity and stability of the solution and reduces uneven oxide film thickness. In cases where leakage current and ESR are reduced, the low-frequency pressure wave of 10KHz-40KHz generated by the anti-cavitation component 15, the micro-jet and shock wave generated by the cavitation effect can increase the turbulence of the solution, reduce the concentration gradient in the solution, and increase the diffusion rate of manganese nitrate ions, so that manganese nitrate ions can penetrate into the pores of the tantalum anode 1 more quickly, and the MnO2 layer after thermal decomposition can be uniformly deposited in a wider area, avoiding the problem of the MnO2 layer being too thin or having voids due to poor permeability, thereby reducing ESR and improving the performance of the tantalum capacitor.

[0042] In addition, when using the energy-enhancing device provided by the present invention, a good energy-enhancing effect can be achieved without a staged pressure-boosting energy-enhancing process, avoiding the problem of long time for multi-stage energy-enhancing and improving efficiency; when using the manganese immersion device provided by the present invention, the number of manganese immersions can be reduced, thereby avoiding problems such as excessive MnO2 layer thickness, cracking or peeling during thermal decomposition caused by multiple manganese immersions, thus improving the quality and performance of the product.

[0043] The following specific experimental examples further illustrate the technical solution and effects of the present invention. It should be noted that the following experimental examples are only for further explanation of the present invention and do not limit the technical solution of the present invention. Example

[0044] Tantalum powder with a specific volume of 70000 μF·V / g was formed into several portions with a weight of 160 mg, a diameter of Ø3 mm, and a pressing density of 5.0 g / cm³. 3 The tantalum billet is heated to 1340℃ and held in a vacuum high-temperature sintering furnace for 25 minutes to obtain sintered tantalum anodes 1. Several tantalum anodes 1 are evenly spot-welded onto a first metal sheet 3 and placed as follows: Figure 1 The tantalum anode 1 was placed in the charging tank 9 shown. A 0.1% concentration of phosphoric acid was used as the charging solution. The heating temperature was 80℃, the charging voltage was 30V, the current density was 80mg / g, and the constant pressure time was 2h. A high-frequency pressure wave with a frequency of 50kHz was applied at 15-minute intervals, with each application lasting 2 minutes, until the charging was completed. The tantalum anode 1 obtained after charging was then placed in a deionized water bath and boiled for 30 minutes, followed by drying in a drying oven at 100℃ for 20 minutes.

[0045] First manganese leaching: Pour a 20% manganese nitrate solution (density approximately 1.22 g / cm³) into manganese leaching tank 14. 3 The tantalum anode 1 is heated to 40°C and then placed in a fixed clamp in the manganese immersion tank 14, so that the manganese nitrate solution just covers the upper part of the tantalum anode 1. The total immersion time is 20 minutes. The frequency of the low-frequency pressure wave is 35KHz, applied once every 2 minutes for 30 seconds each time. After the immersion is completed, the tantalum anode 1 is placed in the coating furnace for thermal decomposition deposition of MnO2 layer. The temperature is set to 220°C and the coating time is 20 minutes.

[0046] Second manganese leaching: Pour a 30% manganese nitrate solution (density approximately 1.34 g / cm³) into manganese leaching tank 14. 3 The solution is heated to 40°C, and the tantalum anode 1, after its first manganese immersion, is placed in a clamp within the manganese immersion tank 14, ensuring the manganese nitrate solution just covers the top of the tantalum anode 1. The immersion time is 20 minutes, with a low-frequency pressure wave at a frequency of 25 kHz applied every 2 minutes for 25 seconds each time. After the manganese immersion is complete, the tantalum anode 1 is placed in a coating furnace for thermal decomposition deposition of a MnO2 layer at a temperature of 220°C for 20 minutes.

[0047] Third manganese leaching: Pour a 30% manganese nitrate solution (density approximately 1.34 g / cm³) into manganese leaching tank 14. 3 The solution is heated to 40°C, and the tantalum anode 1, after its second manganese immersion, is placed in a clamp within the manganese immersion tank 14, ensuring the manganese nitrate solution just covers the top of the tantalum anode 1. The total immersion time is 15 minutes, with a low-frequency pressure wave applied at 15 kHz intervals for 20 seconds each time. After the manganese immersion is complete, the tantalum anode 1 is placed in a coating furnace for thermal decomposition deposition of a MnO2 layer at a temperature of 220°C for 20 minutes.

[0048] The equivalent series resistance of the anode of the prepared tantalum capacitor was measured, and the number of energizing cycles, manganese immersion cycles, and total duration were counted. The results are shown in Table 1.

[0049] Comparative Example The difference between this comparative example and the above embodiments is that it uses the traditional energy-enhancing and manganese-impregnation process, that is, it does not require the use of high-frequency pressure waves and low-frequency pressure waves. The equivalent series resistance of the anode of the prepared tantalum capacitor is detected, and the number of energy-enhancing times, the number of manganese-impregnation times and the total duration are counted. The results are shown in Table 1.

[0050] Table 1. Data Comparison Table of Examples and Comparative Examples

[0051] As can be seen from the data in Table 1, the number of energizing and manganese immersion times in the embodiment is reduced by 2 compared with the comparative example, thereby reducing the energizing time and manganese immersion time. Using the method provided by the present invention, the total energizing time and manganese immersion time in the entire process is reduced by 95 minutes, which improves work efficiency.

[0052] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A method for preparing the anode of a low-ESR tantalum capacitor, characterized in that, During the empowerment process, pressure waves of 20KHz-100KHz are applied intermittently to the empowerment liquid, wherein the temperature of the empowerment liquid is 70℃-90℃, and the 20KHz-100KHz pressure waves are applied once every 10min-30min, each time lasting 1min-5min, until the empowerment process ends. During the manganese immersion process, a pressure wave of 10KHz-40KHz is applied intermittently to the manganese immersion solution, wherein the temperature of the manganese immersion solution is 35℃-45℃, and the 10KHz-40KHz pressure wave is applied once every 2min-4min, and each time it is held for 20s-40s until the manganese immersion process is completed.

2. The method for preparing the anode of a low-ESR tantalum capacitor according to claim 1, characterized in that, The empowerment process specifically includes the following steps: S11. The energy-generating solution is a phosphoric acid solution or a mixed solution of phosphoric acid and ethylene glycol. The tantalum anode is immersed in the mixed solution, and a DC voltage is applied to generate a Ta2O5 dielectric layer. S12. Heat the temperature of the mixed solution to 70℃-90℃.

3. The method for preparing the anode of a low-ESR tantalum capacitor according to claim 1, characterized in that, The manganese immersion process specifically includes the following steps: S21. The tantalum anode obtained after being charged is boiled and dried with deionized water; S22. The manganese immersion solution is a manganese nitrate solution. The tantalum anode is immersed in the manganese nitrate solution to undergo thermal decomposition and generate a MnO2 layer. S23. Maintain the temperature of the manganese nitrate solution at 35℃-45℃.

4. The method for preparing the anode of a low-ESR tantalum capacitor according to claim 3, characterized in that, The manganese immersion process includes 2 to 4 manganese immersion steps, and as the number of manganese immersion steps increases, the frequency and application time of the pressure wave decrease sequentially.

5. The method for preparing the anode of a low-ESR tantalum capacitor according to claim 4, characterized in that, When the manganese immersion process includes three manganese immersion steps, in the first manganese immersion, the concentration of the manganese nitrate solution is 20%, the frequency of the pressure wave is 35KHz, and it is applied once every 2 minutes for 30 seconds each time.

6. The method for preparing the anode of a low-ESR tantalum capacitor according to claim 5, characterized in that, When the manganese immersion process includes three manganese immersion steps, in the second manganese immersion, the concentration of the manganese nitrate solution is 30%, the frequency of the pressure wave is 25KHz, and it is applied once every 2 minutes for 25 seconds each time.

7. The method for preparing the anode of a low-ESR tantalum capacitor according to claim 6, characterized in that, When the manganese immersion process includes three manganese immersion steps, in the third manganese immersion, the concentration of the manganese nitrate solution is 30%, the frequency of the pressure wave is 15KHz, and it is applied once every 2 minutes for 20 seconds each time.

8. A system for fabricating a low-ESR tantalum capacitor anode, characterized in that, The device includes an energy-generating device and a manganese-immersion device. The energy-generating device is equipped with a permeation defoaming component, which can generate pressure waves of 20KHz-100KHz. The manganese-immersion device is equipped with an air-raid shelter component, which can generate pressure waves of 10KHz-40KHz.

9. The fabrication system for the low ESR tantalum capacitor anode according to claim 8, characterized in that, The energy-enhancing device specifically includes a first metal sheet, a circulating water pump, an energy-enhancing tank, an overflow plate, and an energy-enhancing DC power supply. The energy-enhancing tank is used to hold the energy-enhancing solution. The first metal sheet is set on the opening of the energy-enhancing tank through an insulating gasket. A plurality of first tantalum wires are spaced apart on the lower surface of the first metal sheet. The tantalum anode to be energized is set on the first tantalum wires. The positive terminal of the energy-enhancing DC power supply is connected to the first metal sheet, and the negative terminal is connected to the energy-enhancing tank. The overflow plate is vertically set in the energy-enhancing tank, forming a replenishment chamber between itself and one side of the energy-enhancing tank. The height of the overflow plate is higher than the height of the tantalum anode to ensure the level of the energy-enhancing solution, so that the solution just covers the upper part of the tantalum anode. The overflowing solution flows to the replenishment chamber. The circulating water pump is connected to the replenishment chamber and the energy-enhancing tank to pump the solution in the replenishment chamber back into the energy-enhancing tank to achieve solution circulation. A first heater is set at the lower part of the energy-enhancing tank, and the permeation defoaming component is set on the outer wall of the energy-enhancing tank.

10. The fabrication system for the low ESR tantalum capacitor anode according to claim 8, characterized in that, The manganese immersion device specifically includes a second metal sheet and a conical manganese immersion tank. The conical manganese immersion tank is used to hold the manganese immersion solution. The second metal sheet is disposed at the opening of the conical manganese immersion tank. Several second tantalum wires are spaced apart on the lower surface of the second metal sheet. The tantalum anode to be immersed in manganese is disposed on the second tantalum wires. The conical part of the conical manganese immersion tank is provided with a discharge port. The lower part of the conical manganese immersion tank is provided with a second heater. The air-raid shelter assembly is disposed on the outer wall of the conical manganese immersion tank.

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