CN116246888A - Manganese dioxide cathode of anti-surge tantalum electrolytic capacitor, capacitor and preparation method thereof - Google Patents

Abstract

The invention discloses a manganese dioxide cathode of a surge-resistant tantalum electrolytic capacitor, a capacitor and a preparation method thereof. The preparation method of the manganese dioxide cathode comprises the following steps: providing a tantalum core coated with a tantalum pentoxide dielectric film anode, and put it into manganese nitrate solutions of different specific gravity for impregnation, high-temperature water vapor decomposition, and after repeated operations, the first cathode layer is formed on the tantalum pentoxide dielectric film; the first cathode layer is formed on the surface of the first cathode layer by electrochemical means The second cathode layer is then heat-treated to form the manganese dioxide cathode. The invention improves the integrity and continuity of the manganese dioxide cathode layer, greatly reduces the risk of combustion and explosion of the tantalum electrolytic capacitor while maintaining the excellent performance of the tantalum electrolytic capacitor, and improves the use safety of the tantalum electrolytic capacitor.

Description

Manganese dioxide cathode of anti-surge tantalum electrolytic capacitor, capacitor and preparation method thereof

technical field

The invention relates to the field of ceramic capacitors, in particular to a manganese dioxide cathode of a surge-resistant tantalum electrolytic capacitor, a capacitor and a preparation method thereof.

Background technique

With the rapid development of the electronic information industry, integration, miniaturization, high frequency and high density have become the main trends in the development of electronic components. Tantalum electrolytic capacitors are widely used in small complete electronic equipment such as mobile communications, notebook computers, palmtop computers, and automotive electronics because of their higher volume-specific capacity, good temperature stability, and frequency stability. , aerospace, oil drilling and other aspects also have good application prospects. However, the electrolyte layer of an ordinary chip-type solid electrolyte tantalum capacitor is composed of manganese dioxide. The manganese dioxide layer in the prior art is formed by using manganese nitrate to decompose and accumulate many times at a certain temperature. There are random and The problem of discontinuity leads to a large resistance of the tantalum capacitor, which is prone to the risk of burning and explosion due to the surge current in the circuit during actual use.

In view of this, it is very important to propose a tantalum electrolytic capacitor with excellent surge current resistance and a preparation method thereof.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, and provide a manganese dioxide cathode of a surge-resistant tantalum electrolytic capacitor, a capacitor and a preparation method thereof, which can effectively improve the surge current resistance performance of the tantalum electrolytic capacitor.

In order to achieve the above object, the technical solution of the present invention is:

A preparation method of a manganese dioxide cathode of a surge-resistant tantalum electrolytic capacitor, comprising the following steps:

1) Provide a tantalum core anode coated with a tantalum pentoxide dielectric film, and put it into manganese nitrate solutions of different specific gravity for impregnation, high-temperature water vapor decomposition, and after repeated operations, the second tantalum pentoxide dielectric film is formed. a cathode layer;

2) forming a second cathode layer on the surface of the first cathode layer by electrochemical means;

3) heat-treating the sample obtained in step 2 to form a manganese dioxide cathode.

As preferably, the electrochemical method in the step 2 specifically includes:

The tantalum core anode in the sample obtained in step 1 is connected through the external electrode as the positive electrode, and the graphite plate or stainless steel plate is used as the negative electrode, and put into the electrolyte solution with manganese soluble salt as the solute, at 0.1～20mA/cm ² Under the current density, carry out constant current energization for 5-60 minutes.

Preferably, the soluble manganese salts include manganese nitrate, manganese sulfate, manganese chloride, and manganese acetate, water is used as a solvent in the electrolyte solution, and the molar concentration of the soluble manganese salts is 0.01-1 mol/L.

Preferably, the tantalum core anode coated with a tantalum pentoxide dielectric film has a tantalum wire drawn from the tantalum core, and is connected to the external electrode through the tantalum wire.

Preferably, the temperature of the heat treatment is 250-400°C.

Preferably, the time for the heat treatment is 5-60 minutes.

Preferably, the second cathode layer is uniform and dense manganese dioxide, and the grain surface roughness of the second cathode layer is smaller than that of the first cathode layer.

A manganese dioxide cathode for a surge-resistant tantalum electrolytic capacitor is prepared by the above-mentioned preparation method for a manganese dioxide cathode for a surge-resistant tantalum electrolytic capacitor.

A method for preparing a solid chip tantalum electrolytic capacitor, comprising a preparation step of a tantalum core anode, a preparation step of a tantalum pentoxide dielectric film, and a preparation method of the manganese dioxide cathode of the surge-resistant tantalum electrolytic capacitor.

A solid chip tantalum electrolytic capacitor is prepared by the above-mentioned preparation method of the solid chip tantalum electrolytic capacitor.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The present invention performs strengthening treatment on the basis of the first cathode layer obtained by impregnation and high-temperature water vapor decomposition, and prepares a second cathode layer with uniform density and good consistency on the first cathode layer by electrochemical means, and passes Heat treatment makes manganese dioxide perform better.

(2) The grain surface roughness of the second cathode layer of the solid chip tantalum electrolytic capacitor prepared by the present invention is less than the grain surface roughness of the manganese dioxide cathode formed by impregnating pyrolysis, and the surface is smoother and denser manganese dioxide The cathode layer ensures the continuity of the conductive layer of the film layer and plays a key role in improving the surge current performance. The invention not only improves the integrity and continuity of the manganese dioxide cathode layer, but also avoids the heating and burning caused by large local resistance while maintaining the excellent performance of the tantalum electrolytic capacitor, and avoids the risk of tip discharge caused by surface protrusions , It can also greatly reduce the risk of burning and explosion of tantalum capacitors, and improve the safety of tantalum electrolytic capacitors.

(3) The finished product of the solid chip tantalum electrolytic capacitor prepared by the present invention has a higher pass rate after aging, and the product has no leakage current increase or short-circuit failure after the surge current test, effectively improving the pass rate and product safety after the surge current test sex.

Description of drawings

The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments and together with the description serve to explain principles of the invention. Other embodiments and many intended advantages of the embodiments will readily be appreciated as they become better understood by reference to the following detailed description.

Fig. 1 is the scanning electron microscope image of the manganese dioxide cathode of the solid chip tantalum electrolytic capacitor prepared by embodiment 1 of the present application;

Fig. 2 is the scanning electron microscope image of the manganese dioxide cathode of the solid chip tantalum electrolytic capacitor prepared by comparative example 1 of the present application;

Fig. 3 is the scanning electron microscope image of the manganese dioxide cathode of the solid chip tantalum electrolytic capacitor prepared by comparative example 3 of the present application;

FIG. 4 is a scanning electron microscope image of the manganese dioxide cathode of the solid chip tantalum electrolytic capacitor prepared in Comparative Example 4 of the present application.

Detailed ways

The application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain related inventions, rather than to limit the invention. It should also be noted that, for the convenience of description, only the parts related to the related invention are shown in the drawings.

It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and embodiments.

A method for preparing a manganese dioxide cathode of a surge-resistant tantalum electrolytic capacitor is proposed in an embodiment of the present invention, comprising the following steps:

1) Provide a tantalum core anode coated with a tantalum pentoxide dielectric film, and put it into manganese nitrate solutions of different specific gravity for impregnation, high-temperature water vapor decomposition, and after repeated operations, the second tantalum pentoxide dielectric film is formed. a cathode layer;

2) The second cathode layer is formed on the surface of the first cathode layer by electrochemical means. Specifically, the external electrode is connected to the tantalum core anode in the sample obtained in step 1 as the positive electrode, and the graphite plate or stainless steel plate is used as the negative electrode. And put it into the electrolytic solution with the soluble salt of manganese as the solute, and carry out constant current charging for 5-60 minutes under the current density of 0.1-20mA/cm ² .

3) heat-treating the sample in step 2 at a temperature of 250-400° C. for 5-60 minutes to form a manganese dioxide cathode.

In a specific embodiment, the soluble salt of manganese includes manganese nitrate, manganese sulfate, manganese chloride, and manganese acetate, water is used as a solvent in the electrolyte solution, and the molar concentration of the soluble salt of manganese is 0.01˜1 mol/L.

Specifically, the tantalum core anode coated with the tantalum pentoxide dielectric film has a tantalum wire drawn from the tantalum core, and is connected to the external electrode through the tantalum wire. The second cathode layer is uniform and dense manganese dioxide with a smooth grain surface, and the grain surface roughness of the second cathode layer is smaller than that of the first cathode layer.

A manganese dioxide cathode for a surge-resistant tantalum electrolytic capacitor is prepared by the above-mentioned preparation method for a manganese dioxide cathode for a surge-resistant tantalum electrolytic capacitor.

A method for preparing a solid chip tantalum electrolytic capacitor, comprising a preparation step of a tantalum core anode, a preparation step of a tantalum pentoxide dielectric film, a preparation method of the manganese dioxide cathode of the surge-resistant tantalum electrolytic capacitor, and a packaging step. The preparation method of the tantalum core anode and the preparation method of the tantalum pentoxide dielectric film adopt the existing conventional method, and the tantalum core anode is formed by pressing and sintered under high temperature and vacuum conditions. The tantalum pentoxide dielectric film is prepared electrochemically.

A solid chip tantalum electrolytic capacitor is basically the same in structure as the traditional chip solid electrolytic tantalum capacitor, and is prepared by the above-mentioned preparation method of the solid chip tantalum electrolytic capacitor. That is, first press the tantalum powder particles according to the design, and carry out vacuum sintering to obtain a tantalum core anode, then electrochemically form a tantalum pentoxide dielectric film, and then cover it with manganese dioxide as a cathode, and finally assemble the pellets. Epoxy resin molded and sealed products. However, because it is a high-safety product, in the preparation process of the manganese dioxide cathode, the above-mentioned preparation method of the manganese dioxide cathode of the surge-resistant tantalum electrolytic capacitor is adopted, and a new preparation process and solution formula are adopted, and finally the surge Tantalum electrolytic capacitors with excellent current performance.

The present invention will be further described below in conjunction with specific examples, but the scope and application of the present invention will not be limited.

Example 1

This embodiment proposes a method for preparing a solid chip tantalum electrolytic capacitor, comprising the following steps:

1) Anode design: select tantalum metal powder with uniform particle size, calculate the weight of the required tantalum powder, insert tantalum wire into it and press it into a square shape, and then sinter it into a porous matrix tantalum core anode under high temperature and vacuum conditions.

2) Dielectric film formation: use nitric acid as an electrolyte to prepare an aqueous solution as a forming liquid, and electrochemically form the above-mentioned tantalum core anode in the forming liquid to form a tantalum pentoxide medium with uniform thickness and good consistency on the surface of the tantalum core anode membrane.

3) Preparation of the first cathode layer: put the above-mentioned tantalum pentoxide dielectric film-formed tantalum core anode into manganese nitrate solutions of different specific gravity for immersion, high-temperature water vapor decomposition, and repeated operations to form the first cathode layer. The first cathode layer is manganese dioxide.

4) Strengthening treatment of the first cathode layer: Put the above-mentioned tantalum core anode with the first cathode layer into the electrolyte with manganese nitrate (Mn(NO ₃ ) ₂ ) to prepare an aqueous solution with a molar concentration of 0.1 mol/L. The external electrode is connected to the tantalum core anode as the positive electrode, and the graphite plate is used as the negative electrode, and a constant current is applied for 30 minutes at a current density of 20mA/cm ² , and a layer is prepared on the surface of the first cathode layer formed in the preparation step of the first cathode layer. A uniform and dense layer of manganese dioxide is used as the second cathode layer, and then heat-treated at 250° C. for 20 minutes to finally obtain a manganese dioxide cathode.

5) Assembling chip tantalum capacitors: Prepare a graphite layer and a silver layer successively on the outside of the tantalum core anode after step 4 by dipping, and then mount the tantalum core anode on the negative electrode of the lead frame with silver paste, and weld The tantalum wire of the tantalum core anode is connected to the positive lead frame by the method, and then molded and packaged, aged and tested by epoxy resin.

Example 2

This embodiment proposes a method for preparing a solid chip tantalum electrolytic capacitor, comprising the following steps:

1) Anode design: select tantalum metal powder with uniform particle size, calculate the weight of the required tantalum powder, insert tantalum wire into it and press it into a square shape, and then sinter it into a porous matrix tantalum core anode under high temperature and vacuum conditions;

2) Dielectric film formation: the aqueous solution prepared with nitric acid as the electrolyte is used as the forming liquid, and the above-mentioned tantalum core anode is electrochemically formed on the surface of the tantalum core anode in the forming liquid to form a tantalum pentoxide dielectric film with uniform thickness and good consistency ;

3) Preparation of the first cathode layer: put the above-mentioned tantalum pentoxide dielectric film-formed tantalum core anode into manganese nitrate solutions of different specific gravity for immersion, high-temperature water vapor decomposition, and repeated operations to form the first cathode layer. The first cathode layer is manganese dioxide.

4) Strengthening treatment of the first cathode layer: put the above-mentioned tantalum core anode formed with the first cathode layer into an aqueous solution with a molar concentration of 0.01 mol/L using manganese chloride (MnCl ₂ ) as electrolyte. The external electrode is connected to the tantalum core anode as the positive electrode, and the graphite plate is used as the negative electrode, and a constant current is applied for 60 minutes at a current density of 10mA/cm ² , and a layer is prepared on the surface of the first cathode layer formed in the preparation step of the first cathode layer. A uniform and dense layer of manganese dioxide is used as the second cathode layer, and then heat-treated at 350° C. for 10 minutes to finally obtain a manganese dioxide cathode.

5) Assembling chip tantalum capacitors: Prepare a graphite layer and a silver layer successively on the outside of the tantalum core anode after step 4 by dipping, and then mount the tantalum core anode on the negative electrode of the lead frame with silver paste, and weld The tantalum wire of the tantalum core anode is connected to the positive lead frame by the method, and then molded and packaged, aged and tested by epoxy resin.

Example 3

This embodiment proposes a method for preparing a solid chip tantalum electrolytic capacitor, comprising the following steps:

1) Anode design: select tantalum metal powder with uniform particle size, calculate the weight of the required tantalum powder, insert tantalum wire into it and press it into a square shape, and then sinter it into a porous matrix tantalum core anode under high temperature and vacuum conditions;

2) Dielectric film formation: the aqueous solution prepared with nitric acid as the electrolyte is used as the forming liquid, and the above-mentioned tantalum core anode is electrochemically formed on the surface of the tantalum core anode in the forming liquid to form a tantalum pentoxide dielectric film with uniform thickness and good consistency ;

3) Preparation of the first cathode layer: put the above-mentioned tantalum pentoxide dielectric film-formed tantalum core anode into manganese nitrate solutions of different specific gravity for immersion, high-temperature water vapor decomposition, and repeated operations to form the first cathode layer. The first cathode layer is manganese dioxide.

4) Strengthening treatment of the first cathode layer: Put the above-mentioned tantalum core anode with the first cathode layer into the electrolyte with manganese sulfate (MnSO ₄ ) to prepare an aqueous solution with a molar concentration of 1 mol/L. The external electrode is connected to the tantalum core anode as the positive electrode, and the graphite plate is used as the negative electrode, and the current density of 0.1mA/ ^cm2 is energized at a constant current for 5 minutes, and the surface of the first cathode layer formed in the preparation step of the first cathode layer is prepared. A layer of uniform and dense manganese dioxide is used as the second cathode layer, and then heat-treated at 400° C. for 5 minutes to finally obtain the manganese dioxide cathode.

5) Assembling chip tantalum capacitors: Prepare a graphite layer and a silver layer successively on the outside of the tantalum core anode after step 4 by dipping, and then mount the tantalum core anode on the negative electrode of the lead frame with silver paste, and weld The tantalum wire of the tantalum core anode is connected to the positive lead frame by the method, and then molded and packaged, aged and tested by epoxy resin.

Comparative example 1

This comparative example proposes a preparation method of a solid chip tantalum electrolytic capacitor, comprising the following steps:

1) Anode design: select tantalum metal powder with uniform particle size, calculate the weight of the required tantalum powder, insert tantalum wire into it and press it into a square shape, and then sinter it into a porous matrix tantalum core anode under high temperature and vacuum conditions;

2) Dielectric film formation: the aqueous solution prepared with nitric acid as the electrolyte is used as the forming liquid, and the above-mentioned tantalum core anode is electrochemically formed in the forming liquid to form a tantalum pentoxide medium with uniform thickness and good consistency on the surface of the tantalum core anode membrane;

3) Manufacturing of manganese dioxide cathode: Put the above-mentioned tantalum core anode formed with tantalum pentoxide dielectric film into manganese nitrate solutions of different specific gravity for immersion, high temperature water vapor decomposition, and form manganese dioxide cathode after repeated operations.

4) Assembling chip tantalum capacitors: Prepare a graphite layer and a silver layer successively on the outside of the tantalum core anode after step 3 by dipping, then mount the tantalum core anode on the negative electrode of the lead frame with silver paste, and weld The tantalum wire of the tantalum core anode is connected to the positive lead frame by the method, and then molded and packaged, aged and tested by epoxy resin.

Comparative example 2

This comparative example proposes a preparation method of a solid chip tantalum electrolytic capacitor, comprising the following steps:

1) Anode design: select tantalum metal powder with uniform particle size, calculate the weight of the required tantalum powder, insert tantalum wire into it and press it into a square shape, and then sinter it into a porous matrix tantalum core anode under high temperature and vacuum conditions;

2) Dielectric film formation: the aqueous solution prepared with nitric acid as the electrolyte is used as the forming liquid, and the above-mentioned tantalum core anode is electrochemically formed on the surface of the tantalum core anode in the forming liquid to form a tantalum pentoxide dielectric film with uniform thickness and good consistency ;

3) Preparation of the first cathode layer: put the above-mentioned tantalum pentoxide dielectric film-formed tantalum core anode into manganese nitrate solutions of different specific gravity for immersion, high-temperature water vapor decomposition, and repeated operations to form the first cathode layer. The first cathode layer is manganese dioxide.

4) Strengthening treatment of the first cathode layer: Put the above-mentioned tantalum core anode with the first cathode layer into the electrolyte with manganese sulfate (MnSO ₄ ) to prepare an aqueous solution with a molar concentration of 1 mol/L. The external electrode is connected to the tantalum core anode as the positive electrode, and the graphite plate is used as the negative electrode, and the current density of 0.1mA/ ^cm2 is energized at a constant current for 5 minutes, and the surface of the first cathode layer formed in the preparation step of the first cathode layer is prepared. A layer of uniform and dense manganese dioxide is used as the second cathode layer to obtain a manganese dioxide cathode.

5) Assembling chip tantalum capacitors: Prepare a graphite layer and a silver layer successively on the outside of the tantalum core anode after step 4 by dipping, and then mount the tantalum core anode on the negative electrode of the lead frame with silver paste, and weld The tantalum wire of the tantalum core anode is connected to the positive lead frame by the method, and then molded and packaged, aged and tested by epoxy resin.

Comparative example 3

This comparative example proposes a preparation method of a solid chip tantalum electrolytic capacitor, comprising the following steps:

1) Anode design: select tantalum metal powder with uniform particle size, calculate the weight of the required tantalum powder, insert tantalum wire into it and press it into a square shape, and then sinter it into a porous matrix tantalum core anode under high temperature and vacuum conditions;

2) Dielectric film formation: the aqueous solution prepared with nitric acid as the electrolyte is used as the forming liquid, and the above-mentioned tantalum core anode is electrochemically formed on the surface of the tantalum core anode in the forming liquid to form a tantalum pentoxide dielectric film with uniform thickness and good consistency ;

3) Preparation of the cathode layer: put the above-mentioned tantalum core anode formed with the tantalum pentoxide dielectric film into manganese nitrate solutions of different specific gravity for immersion, high-temperature water vapor decomposition, and form a manganese dioxide layer after repeated operations. The manganese dioxide was heat-treated at 400° C. for 10 minutes to finally obtain the manganese dioxide cathode.

4) Assembling chip tantalum capacitors: Prepare a graphite layer and a silver layer successively on the outside of the tantalum core anode after step 3 by dipping, then mount the tantalum core anode on the negative electrode of the lead frame with silver paste, and weld The tantalum wire of the tantalum core anode is connected to the positive lead frame by the method, and then molded and packaged, aged and tested by epoxy resin.

Comparative example 4

This comparative example proposes a preparation method of a solid chip tantalum electrolytic capacitor, comprising the following steps:

1) Anode design: select tantalum metal powder with uniform particle size, calculate the weight of the required tantalum powder, insert tantalum wire into it and press it into a square shape, and then sinter it into a porous matrix tantalum core anode under high temperature and vacuum conditions;

2) Dielectric film formation: the aqueous solution prepared with nitric acid as the electrolyte is used as the forming liquid, and the above-mentioned tantalum core anode is electrochemically formed on the surface of the tantalum core anode in the forming liquid to form a tantalum pentoxide dielectric film with uniform thickness and good consistency ;

3) Preparation of the first cathode layer: put the tantalum core anode formed with the tantalum pentoxide dielectric film above into manganese nitrate solutions of different specific gravity for immersion, high-temperature water vapor decomposition, and form a manganese dioxide layer after repeated operations. Finally, the first cathode layer of manganese dioxide is obtained.

4) Strengthening treatment of the first cathode layer: put the above-mentioned tantalum core anode that has formed the first cathode layer into the ammonium acetate containing 0.03wt% nonylphenol polyoxyethylene ether as a viscosity reducer, and 0.1wt% ethanol as a dispersant The manganese nitrate solution with specific gravity of 1.3g/cm ³ is immersed once, and then the tantalum core is decomposed for 6 minutes at a temperature of 260°C, a water vapor pressure of 0.05MPa, and an oxygen mass percentage concentration of 9% to obtain carbon dioxide manganese cathode.

5) Assembling chip tantalum capacitors: Prepare a graphite layer and a silver layer successively on the outside of the tantalum core anode after step 4 by dipping, and then mount the tantalum core anode on the negative electrode of the lead frame with silver paste, and weld The tantalum wire of the tantalum core anode is connected to the positive lead frame by the method, and then molded and packaged, aged and tested by epoxy resin.

The solid chip tantalum electrolytic capacitors prepared in Examples 1-3 and Comparative Example were subjected to aging test and surge current test, and the results shown in Table 1 were obtained.

Table 1 comparative example and the surge current test qualified rate statistics of embodiment

As shown in Figure 1, it is a scanning electron microscope image of the second cathode layer prepared by electrochemical means in step 4 of Example 1, and as shown in Figure 2-4, it is prepared by Comparative Example 1 and Comparative Examples 3 and 4 respectively Scanning electron microscope image of a manganese dioxide cathode. It can be seen from the figure that the embodiment of the present application adopts electrochemical strengthening treatment on the basis of the first cathode layer to obtain a manganese dioxide layer with a smaller grain surface roughness, and is uniform and dense, and the manganese dioxide layer It is more coherent and complete, so it can make the surge current resistance performance more excellent. However, the manganese dioxide cathodes prepared in Comparative Example 1 and Comparative Examples 3 and 4 had relatively rough grain surfaces, resulting in poor surge current resistance. However, in comparative example 2, the conductivity of the manganese dioxide layer prepared only electrochemically is relatively poor, and the conductivity can be significantly improved by heat treatment. The ESR of the solid chip tantalum electrolytic capacitor can be effectively reduced and the electrical performance can be improved by combining the electrochemical method with heat treatment.

The manganese dioxide cathode of the tantalum electrolytic capacitor proposed by the present invention, the tantalum electrolytic capacitor and the preparation method thereof, the manganese dioxide layer on the surface of the tantalum capacitor is uniform and dense, the consistency is good, and the qualified rate of the finished product after aging is higher, reaching more than 90%. , After the surge current test, the product has no leakage current increase or short-circuit failure, and the pass rate after the surge current test can be as high as 100%, which effectively improves the safety of tantalum electrolytic capacitors.

The specific implementation of the present application has been described above, but the protection scope of the present application is not limited thereto. Anyone familiar with the technical field can easily think of changes or replacements within the technical scope disclosed in the present application, and should be included in the scope of the present application. Within the protection scope of this application. Therefore, the protection scope of the present application should be determined by the protection scope of the claims.

Claims (10)

1. a preparation method of the manganese dioxide negative electrode of anti-surge tantalum electrolytic capacitor, is characterized in that, comprises the following steps: 1) Provide a tantalum core anode coated with a tantalum pentoxide dielectric film, and put it into manganese nitrate solutions of different specific gravity for impregnation, high-temperature water vapor decomposition, and after repeated operations, the second tantalum pentoxide dielectric film is formed. a cathode layer; 2) forming a second cathode layer on the surface of the first cathode layer by electrochemical means; 3) heat-treating the sample obtained in step 2 to form a manganese dioxide cathode. 2. the preparation method of the manganese dioxide negative electrode of anti-surge tantalum electrolytic capacitor according to claim 1, is characterized in that, the electrochemical mode in described step 2 specifically comprises: The tantalum core anode in the sample obtained in step 1 is connected through the external electrode as the positive electrode, and the graphite plate or stainless steel plate is used as the negative electrode, and put into the electrolyte solution with manganese soluble salt as the solute, at 0.1～20mA/cm ² Under the current density, carry out constant current energization for 5-60 minutes. 3. the preparation method of the manganese dioxide negative electrode of anti-surge tantalum electrolytic capacitor according to claim 2, is characterized in that, the soluble salt of described manganese comprises manganese nitrate, manganese sulfate, manganese chloride, manganese acetate, described Water is used as a solvent in the electrolyte solution, and the molar concentration of the soluble manganese salt is 0.01˜1 mol/L. 4. the preparation method of the manganese dioxide negative electrode of anti-surge tantalum electrolytic capacitor according to claim 2 is characterized in that, the tantalum core anode that described has been coated with tantalum pentoxide dielectric film has the tantalum core anode that draws from tantalum core A tantalum wire connected to the external electrode through the tantalum wire. 5 . The method for preparing the manganese dioxide cathode of a surge-resistant tantalum electrolytic capacitor according to claim 1 , wherein the temperature of the heat treatment is 250-400° C. 6 . The method for preparing the manganese dioxide cathode of a surge-resistant tantalum electrolytic capacitor according to claim 1 , wherein the heat treatment time is 5 to 60 minutes. 7. the preparation method of the manganese dioxide negative electrode of anti-surge tantalum electrolytic capacitor according to claim 1, is characterized in that, described second cathode layer is the manganese dioxide of uniform density, and the manganese dioxide of described second cathode layer The grain surface roughness is smaller than the grain surface roughness of the first cathode layer. 8. A manganese dioxide cathode of a surge-resistant tantalum electrolytic capacitor, characterized in that it is prepared by the preparation method of the manganese dioxide cathode of a surge-resistant tantalum electrolytic capacitor according to any one of claims 1-7 . 9. A method for preparing a solid chip tantalum electrolytic capacitor, characterized in that it comprises a preparation step of a tantalum core anode, a preparation step of a tantalum pentoxide dielectric film, and the wave-resistant method described in any one of claims 1-7. A method for preparing a manganese dioxide cathode of a tantalum electrolytic capacitor. 10. A solid chip tantalum electrolytic capacitor, characterized in that it is prepared by the method for preparing a solid chip tantalum electrolytic capacitor according to claim 9.

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