A method of manufacturing a tantalum capacitor

Abstract

The present application provides a tantalum capacitor manufacturing method, comprising the following steps: preparing a tantalum block; generating a dielectric oxide film on the surface of the tantalum block by acid solution immersion; mixing mucilage and a salt compound to prepare an electrolyte, and generating a tantalum pentoxide film on the surface of the tantalum block by electrochemical reaction; coating a cathode on the surface of the tantalum block to prepare a tantalum capacitor. The technical scheme of the present application generates a tantalum pentoxide film by electrochemical reaction, so that the thickness and compactness of the tantalum pentoxide film can be easily controlled, and the voltage resistance of the tantalum capacitor is maximally improved; the mixed solution of high-viscosity mucilage and a salt compound is used as the electrolyte, which prevents the tantalum block core material from being affected during the electrochemical reaction process, ensures the compactness of the tantalum pentoxide film, prevents the capacity of the tantalum capacitor from decreasing, and significantly improves the film generation efficiency of the tantalum pentoxide film, so that the thickness of the generated tantalum pentoxide film is thicker within the same electrochemical reaction time, and the voltage resistance of the tantalum capacitor is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of capacitor manufacturing technology, and particularly relates to a method for manufacturing tantalum capacitors. Background Technology

[0002] Tantalum capacitors are fundamental electronic components in electronic engineering, widely used in communication equipment, audio-visual systems, electrical instruments, and many other fields. In the manufacturing process of tantalum capacitors, a dielectric oxide film is first formed on the tantalum metal surface. Then, the tantalum metal surface is energized through mechanical or chemical methods to form a tantalum pentoxide film. Due to the skin effect, current concentrates on the conductor surface in tantalum capacitors, with the outer layer carrying a larger current. The thickness of the tantalum pentoxide film is directly proportional to the voltage; therefore, the thickness of the tantalum pentoxide film determines the voltage withstand capability and capacitance of the tantalum capacitor.

[0003] In the prior art, patent document CN120453064A discloses a method for improving the withstand voltage of a chip tantalum capacitor. The method includes: forming a dielectric oxide film in an acidic solution using a tantalum anode block formed by powder metallurgy; then placing it in a sputtering coating apparatus, introducing oxygen, using tantalum as the target material, and forming a tantalum pentoxide film on its surface; finally, forming a chip tantalum capacitor by coating it with manganese dioxide or a polymer cathode. This patented technology utilizes a sputtering coating apparatus to generate the tantalum pentoxide film, essentially using a mechanical method to generate the tantalum pentoxide film, improving its density. However, during the mechanical generation of the tantalum pentoxide film, the sputtering coating apparatus essentially affects the tantalum metal core material. Although this increases the thickness of the tantalum pentoxide film, it also damages the tantalum metal core material, resulting in a significant reduction in the capacitance of the manufactured tantalum capacitor. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for manufacturing a tantalum capacitor.

[0005] The present invention is achieved through the following technical solutions.

[0006] This invention provides a method for manufacturing a tantalum capacitor, comprising the following steps: Step 1: Tantalum powder is pressed and sintered using powder metallurgy to obtain tantalum blocks; Step 2: Immerse the tantalum block from Step 1 in an acidic solution to form a dielectric oxide film on the surface of the tantalum block; Step 3: First, a viscous liquid with a viscosity of not less than 1400 mPa·s is uniformly mixed with a salt compound to prepare an electrolyte. Then, the tantalum block described in Step 2 is immersed in the electrolyte, a power source is provided, and the current generated by the power source flows continuously through the tantalum block and the electrolyte. After the tantalum block undergoes an electrochemical reaction, a tantalum pentoxide film is formed on the surface of the tantalum block. Step 4: First, the surface of the tantalum block described in Step 3 is coated with a cathode, and then the tantalum block and the cathode are encapsulated together to obtain a tantalum capacitor.

[0007] The porosity of the tantalum block mentioned in step one is 20%-80%.

[0008] The acidic solution mentioned in step two is one or more of phosphoric acid, nitric acid, acetic acid, and hydrochloric acid.

[0009] The mucus described in step three is a polyol containing at least three hydroxyl groups.

[0010] The salt compound mentioned in step three is one or more of potassium salts, ammonium salts, and sodium salts.

[0011] The rated voltage of the power supply mentioned in step three is 220V-1760V.

[0012] The current density in the electrolyte mentioned in step three is 5-500 mg / A.

[0013] The electrochemical reaction duration of the tantalum block in step three is 5-500 min.

[0014] The cathode material mentioned in step four is manganese dioxide.

[0015] The tantalum capacitor described in step four is a surface-mount capacitor.

[0016] The beneficial effects of this invention are as follows: By employing the technical solution of this invention, an electrochemical reaction is used instead of the existing mechanical method, which avoids affecting the tantalum core material, prevents the capacitance of the tantalum capacitor from decreasing, promotes the outward growth of the dielectric oxide film, and makes it easier to control the duration and intensity of the electrochemical reaction, as well as the thickness of the tantalum pentoxide film, maximizing the thickness of the tantalum pentoxide film and thus improving the voltage withstand capability of the tantalum capacitor. Furthermore, compared to the existing methods for chemically generating tantalum pentoxide films, this invention uses a mixed solution of high-viscosity viscous liquid and salt compounds as the electrolyte. On the one hand, due to the higher viscosity of the electrolyte, it cannot penetrate into the tantalum metal core, allowing the tantalum pentoxide film to grow outward, which improves the density of the generated tantalum pentoxide film and prevents the capacitance of the tantalum capacitor from decreasing. On the other hand, the ionization of the salt compounds in the electrolyte increases the conductivity of the electrolyte, significantly improving the generation efficiency of the tantalum pentoxide film. Within the same electrochemical reaction time, the generated tantalum pentoxide film is thicker, significantly improving the voltage withstand performance of the tantalum capacitor. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of the present invention; Figure 2 The morphological photograph of the capacitor under a microscope was obtained using the technical solution of this invention; Figure 3 Ethylene glycol was used as an electrolyte component. The tantalum block was immersed in the electrolyte for 5 minutes to carry out an electrochemical reaction, and then the morphology of the capacitor was obtained under a microscope. Figure 4 Ethylene glycol is used as an electrolyte component. The tantalum block is immersed in the electrolyte for an electrochemical reaction that lasts for 35 minutes, and then a microscopic image of the capacitor is obtained. Figure 5 The method involves using glycerol as an electrolyte component, immersing a tantalum block in the electrolyte for an electrochemical reaction for 5 minutes, and then obtaining a microscopic image of the capacitor's morphology. Figure 6 The morphology of the capacitor under a microscope is obtained by immersing a tantalum block in the electrolyte and performing an electrochemical reaction for 35 minutes using glycerol as an electrolyte component. Figure 7 The capacitor was photographed under a microscope after immersing a tantalum block in the electrolyte and performing an electrochemical reaction for 65 minutes using glycerol as the electrolyte component. Detailed Implementation

[0018] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0019] like Figures 1 to 2 As shown, the present invention provides a method for manufacturing a tantalum capacitor, comprising the following steps: Step 1: Tantalum powder is pressed and sintered using powder metallurgy to obtain tantalum blocks; Step 2: Immerse the tantalum block from Step 1 in an acidic solution to form a dielectric oxide film on the surface of the tantalum block; Step 3: First, mix the viscous liquid with a viscosity of not less than 1400 mPa·s with the salt compound to obtain an electrolyte. Then, immerse the tantalum block from Step 2 into the electrolyte, provide a power source, and allow the current generated by the power source to continuously flow through the tantalum block and the electrolyte. After the tantalum block undergoes an electrochemical reaction, a tantalum pentoxide film is formed on the surface of the tantalum block. Step 4: First, the tantalum block surface in step 3 is coated with a cathode, and then the tantalum block and the cathode are encapsulated together to obtain a tantalum capacitor.

[0020] The technical solution of this invention uses an electrochemical reaction instead of the existing mechanical method, which avoids affecting the tantalum core material, prevents the capacitance of the tantalum capacitor from decreasing, promotes the outward growth of the dielectric oxide film, and allows for easy control of the electrochemical reaction duration and intensity, as well as the thickness of the tantalum pentoxide film, maximizing the thickness of the tantalum pentoxide film and thus improving the voltage withstand capability of the tantalum capacitor. Furthermore, compared to the existing method of chemically generating tantalum pentoxide film, this invention uses a mixed solution of high-viscosity viscous liquid and salt compounds as the electrolyte. On the one hand, due to the higher viscosity of the electrolyte, it cannot penetrate into the tantalum metal core, forcing the tantalum pentoxide film to grow outward, which improves the density of the generated tantalum pentoxide film and prevents the capacitance of the tantalum capacitor from decreasing. On the other hand, the ionization of the salt compounds in the electrolyte increases the conductivity of the electrolyte, significantly improving the formation efficiency of the tantalum pentoxide film. Within the same electrochemical reaction time, the generated tantalum pentoxide film is thicker, significantly improving the voltage withstand performance of the tantalum capacitor.

[0021] Specifically, the porosity of the tantalum block in step one is 20%-80%. The acidic solution in step two is one or more of phosphoric acid, nitric acid, acetic acid, and hydrochloric acid.

[0022] In addition, the viscous liquid in step three is a polyol containing at least three hydroxyl groups. In this embodiment, glycerol is used as an example. The salt compound in step three is one or more of potassium, ammonium, and sodium salts. The electrolyte temperature is 50-280℃, and the rated voltage of the power supply in step three is 220V-1760V. The current density in the electrolyte in step three is 5-500mg / A. The electrochemical reaction duration of the tantalum block in step three is 5-500min. Using the technical solution of this invention, because the electrolyte contains salt compounds, these compounds ionize within the electrolyte, increasing the electrolyte conductivity and significantly improving the tantalum pentoxide film formation efficiency. Within the same electrochemical reaction time, the generated tantalum pentoxide film is thicker, significantly improving the voltage withstand performance of the tantalum capacitor.

[0023] Specifically, the cathode material in step four is manganese dioxide. The tantalum capacitor in step four is packaged as a surface mount device.

[0024] like Figure 2 As shown, a microscopic image of the capacitor was obtained using the technical solution of this invention. The pink area in the image represents the tantalum pentoxide film. Figure 2 As can be seen, the density of the tantalum pentoxide film is significantly improved.

[0025] like Figure 3 As shown, when ethylene glycol is used as the electrolyte component, its viscosity at 20°C is 21.38 mPa·s, which is much lower than 1400 mPa·s. A tantalum block was immersed in this electrolyte for an electrochemical reaction, which lasted for 5 minutes. The tantalum block was then removed and observed under a microscope. The pink area in the photograph represents the tantalum pentoxide film. Figure 3 As can be seen, the tantalum pentoxide film thickness is still relatively shallow after the electrochemical reaction continues for 5 minutes.

[0026] like Figure 4 As shown, when ethylene glycol is used as the electrolyte component, its viscosity at 20°C is 21.38 mPa·s, which is much lower than 1400 mPa·s. A tantalum block was immersed in this electrolyte for an electrochemical reaction, which lasted for 35 minutes. The tantalum block was then removed and observed under a microscope. The pink area in the photograph represents the tantalum pentoxide film. Figure 4 As can be seen from the table, after the electrochemical reaction lasted for 35 minutes, due to the low viscosity of ethylene glycol, the electrochemical reaction range extended to the core of the tantalum block, causing the tantalum pentoxide film to extend to the core of the tantalum block, which severely damaged the core material of the tantalum block, resulting in a significant reduction in the capacitance of the tantalum capacitor. The measured data are shown in Table 1.

[0027] like Figure 5As shown, when glycerol is used as the electrolyte component, its viscosity at 20°C is 1412-1500 mPa·s. Since the viscosity of glycerol is greater than 1400 mPa·s, a tantalum block was immersed in this electrolyte for an electrochemical reaction. After the electrochemical reaction lasted for 5 minutes, the tantalum block was removed and observed under a microscope. The pink area in the photograph is the tantalum pentoxide film. Figure 5 As can be seen, after the electrochemical reaction lasted for 5 minutes, the tantalum pentoxide film was still relatively thin.

[0028] like Figure 6 As shown, when glycerol is used as part of the electrolyte, its viscosity at 20°C is 1412-1500 mPa·s. Since the viscosity of glycerol is greater than 1400 mPa·s, a tantalum block was immersed in this electrolyte for an electrochemical reaction. After the electrochemical reaction lasted for 35 minutes, the tantalum block was removed, and a photograph was taken under a microscope. The pink area in the photograph is the tantalum pentoxide film. Figure 6 As can be seen, after the electrochemical reaction lasted for 35 minutes, the tantalum pentoxide film was relatively thick, but the tantalum pentoxide film did not penetrate the core material of the tantalum block, and the boundary line between the tantalum pentoxide film and the core material of the tantalum block was obvious.

[0029] like Figure 7 As shown, when glycerol is used as the electrolyte component, its viscosity at 20°C is 1412-1500 mPa·s. Since the viscosity of glycerol is greater than 1400 mPa·s, a tantalum block was immersed in this electrolyte for an electrochemical reaction. After the electrochemical reaction lasted for 65 minutes, the tantalum block was removed and observed under a microscope. The pink area in the photograph is the tantalum pentoxide film. Figure 6 As can be seen, after the electrochemical reaction lasted for 65 minutes, the tantalum pentoxide film was relatively thick, but the tantalum pentoxide film did not penetrate into the tantalum block core material. The boundary between the tantalum pentoxide film and the tantalum block core material was obvious. Due to the low viscosity of glycerol, the electrochemical reaction range could not extend to the tantalum block core, so the tantalum pentoxide film could only grow outward to avoid damage to the tantalum block core material. The measured capacitance data of the obtained tantalum capacitor was basically consistent with the rated data. The measured data are shown in Table 1.

[0030] Table 1. Comparison of measured capacitance data of tantalum capacitors prepared with different electrolyte compositions

Claims

1. A method for manufacturing a tantalum capacitor, characterized in that: Includes the following steps: Step 1: Tantalum powder is pressed and sintered using powder metallurgy to obtain tantalum blocks; Step 2: Immerse the tantalum block from Step 1 in an acidic solution to form a dielectric oxide film on the surface of the tantalum block; Step 3: First, a viscous liquid with a viscosity of not less than 1400 mPa·s is uniformly mixed with a salt compound to prepare an electrolyte. Then, the tantalum block described in Step 2 is immersed in the electrolyte, a power source is provided, and the current generated by the power source is continuously flowing through the tantalum block and the electrolyte. After the tantalum block undergoes an electrochemical reaction, a tantalum pentoxide film is formed on the surface of the tantalum block. Step 4: First, the surface of the tantalum block described in Step 3 is coated with a cathode, and then the tantalum block and the cathode are encapsulated together to obtain a tantalum capacitor.

2. The method for manufacturing a tantalum capacitor as described in claim 1, characterized in that: The porosity of the tantalum block mentioned in step one is 20%-80%.

3. The method for manufacturing a tantalum capacitor as described in claim 1, characterized in that: The acidic solution mentioned in step two is one or more of phosphoric acid, nitric acid, acetic acid, and hydrochloric acid.

4. The method for manufacturing a tantalum capacitor as described in claim 1, characterized in that: The mucus described in step three is a polyol containing at least three hydroxyl groups.

5. The method for manufacturing a tantalum capacitor as described in claim 1, characterized in that: The salt compound mentioned in step three is one or more of potassium salts, ammonium salts, and sodium salts.

6. The method for manufacturing a tantalum capacitor as described in claim 1, characterized in that: The rated voltage of the power supply mentioned in step three is 220V-1760V.

7. The method for manufacturing a tantalum capacitor as described in claim 1, characterized in that: The current density in the electrolyte mentioned in step three is 5-500 mg / A.

8. The method for manufacturing a tantalum capacitor as described in claim 1, characterized in that: The electrochemical reaction duration of the tantalum block in step three is 5-500 min.

9. The method for manufacturing a tantalum capacitor as described in claim 1, characterized in that: The cathode material mentioned in step four is manganese dioxide.

10. The method for manufacturing a tantalum capacitor as described in claim 1, characterized in that: The tantalum capacitor described in step four is a surface mount type.

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