Chip-type solid electrolyte tantalum capacitor capable of ensuring moisture resistance and preparation method of chip-type solid electrolyte tantalum capacitor

Abstract

The invention discloses a chip solid electrolyte tantalum capacitor capable of ensuring moisture resistance and a preparation method thereof, and belongs to the field of capacitor preparation. The tantalum capacitor comprises a tantalum anode, a dielectric layer, a solid electrolyte layer, a graphite silver paste layer, a hydrophobic moisture-proof layer, an epoxy resin shell, a lead frame, a positive lead and a negative lead. Wherein the tantalum anode is sequentially coated with the dielectric layer, the solid electrolyte layer and the graphite silver paste layer from inside to outside; the graphite silver paste layer is adhered to the lead frame through a conductive adhesive to lead out an anode lead and a cathode lead; the graphite silver paste layer is coated with a hydrophobic moisture-proof layer; and the hydrophobic moisture-proof layer is coated and packaged with an epoxy resin shell. According to the tantalum capacitor, the graphite silver paste layer is coated with the specific hydrophobic moisture-proof layer, so that the moisture-proof performance of the chip-type solid electrolyte tantalum capacitor is effectively improved on the premise that the preparation process difficulty, cost and finished product volume are not increased, and the chip-type solid electrolyte tantalum capacitor is suitable for being used in a high-temperature and high-humidity environment; and the product performance is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of tantalum capacitors, and in particular to a chip-type solid electrolyte tantalum capacitor with moisture-proof performance and a preparation method thereof. Background Art

[0002] Chip solid electrolyte tantalum capacitors are widely used in aviation, aerospace, shipbuilding and other fields because of their coupling, filtering, energy storage and other functions. At present, chip solid electrolyte tantalum capacitors have been developed, such as solid manganese dioxide or conductive polymer cathode, which are relatively mature products on the market. In order to protect the capacitor from environmental factors, the commonly used external packaging material is epoxy resin, but because the epoxy resin itself is a porous structure after cross-linking, some water vapor will penetrate when stored in a humid environment, and conductive polymer materials such as PEDT are more sensitive to water vapor. After a long period of water vapor penetration, the organic material will degrade, resulting in the deterioration of the electrical parameters of the capacitor. In addition, the capacitor that absorbs water vapor will crack the shell during the reflow soldering process, and even "popcorn" state, reducing the reliability of the capacitor during use.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The purpose of the present invention is to provide a chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance and a preparation method thereof, which can ensure the moisture-proof performance of the chip-type solid electrolyte tantalum capacitor, thereby solving the problems of poor moisture-proof performance of existing tantalum capacitors, deterioration of electrical performance after absorbing water vapor, and cracking of epoxy shells during high-temperature welding.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance comprises: a tantalum anode, a dielectric layer, a solid electrolyte layer, a graphite silver paste layer, a hydrophobic moisture-proof layer, an epoxy resin shell, a lead frame, a positive electrode lead and a negative electrode lead; wherein,

[0007] The outside of the tantalum anode is coated with a dielectric layer, a solid electrolyte layer and a graphite silver paste layer in sequence from the inside to the outside;

[0008] The graphite silver paste layer is bonded to the lead frame by conductive adhesive to lead out the positive electrode lead and the negative electrode lead;

[0009] The graphite silver paste layer is coated with a hydrophobic moisture-proof layer;

[0010] The hydrophobic moisture-proof layer is coated with an epoxy resin shell.

[0011] A method for preparing a chip-type solid electrolyte tantalum capacitor with moisture-proof performance according to the present invention comprises the following steps:

[0012] Step 1, preparing a tantalum anode: using tantalum powder with a predetermined specific volume and parameters, making a tantalum block according to a predetermined pressing density, and sintering it at a predetermined heating rate within a sintering temperature range to form a tantalum anode block with a predetermined mechanical strength as a tantalum anode;

[0013] Step 2, preparing a dielectric layer: forming a dielectric layer of desired thickness on the tantalum anode prepared in step 1 in an acid-containing anodizing solution;

[0014] Step 3, preparing a solid electrolyte layer: covering the dielectric layer obtained in step 2 with a conductive polymer in situ or in the form of a dispersion after prepolymerization to obtain a solid electrolyte layer of desired thickness;

[0015] Step 4, preparing a graphite silver paste layer: coating a graphite and silver paste layer on the solid electrolyte layer obtained in step 3 to obtain a graphite silver paste layer as a cathode lead-out transition layer;

[0016] Step 5, preparing a hydrophobic moisture-proof layer: bonding the tantalum anode coated with the graphite silver paste layer in step 4 to the lead frame through a conductive adhesive, impregnating the moisture-proof material 1 to 10 times, and thermally curing at 110° C. to 160° C. for 10 min to 60 min to form a hydrophobic moisture-proof layer of a predetermined thickness outside the graphite silver paste layer;

[0017] Step 6, encapsulate the epoxy resin shell:

[0018] The product covered with the moisture-proof layer is encapsulated by injection molding epoxy resin on the outside of the product to form an epoxy resin shell.

[0019] Compared with the prior art, the chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance and the preparation method thereof provided by the present invention have the following beneficial effects:

[0020] By coating the graphite silver paste layer with a hydrophobic moisture-proof layer, water vapor can be blocked from penetrating into the interior of the tantalum capacitor, thus avoiding the degradation of the internal organic materials and the deterioration of the electrical parameters of the tantalum capacitor. Without increasing the difficulty of the preparation process and the volume and cost of the finished capacitor, the moisture-proof performance of the chip-type solid electrolyte tantalum capacitor is guaranteed, solving the problems of poor moisture-proof performance of existing tantalum capacitors, deterioration of electrical performance after absorbing water vapor, and cracking of the epoxy shell during high-temperature welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of a chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance provided in an embodiment of the present invention.

[0023] Figure 2 A flow chart of a method for preparing a chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance provided in an embodiment of the present invention.

[0024] In the figure: 1-tantalum anode; 2-dielectric layer; 3-solid electrolyte layer; 4-graphite silver paste layer; 5-hydrophobic moisture-proof layer; 6-lead frame; 7-epoxy resin shell. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in combination with the specific content of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0026] First, the terms that may be used in this article are explained as follows:

[0027] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0028] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0029] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0030] Unless otherwise specified or limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this article can be understood according to specific circumstances.

[0031] When concentration, temperature, pressure, size or other parameters are expressed in the form of a numerical range, the numerical range should be understood to specifically disclose all ranges formed by the pairing of any upper limit, lower limit, and preferred value in the numerical range, regardless of whether the range is explicitly stated; for example, if a numerical range of "2 to 8" is stated, the numerical range should be interpreted as including ranges such as "2 to 7", "2 to 6", "5 to 7", "3 to 4 and 6 to 7", "3 to 5 and 7", "2 and 5 to 7", etc. Unless otherwise specified, the numerical ranges stated herein include both their end values ​​and all integers and fractions within the numerical range.

[0032] The scheme provided by the present invention is described in detail below. The contents not described in detail in the embodiments of the present invention belong to the prior art known to professionals in the field. If the specific conditions are not specified in the embodiments of the present invention, they are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturers are not specified in the reagents or instruments used in the embodiments of the present invention, they are all conventional products that can be purchased commercially.

[0033] like Figure 1 As shown, the embodiment of the present invention provides a chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance, including: a tantalum anode 1, a dielectric layer 2, a solid electrolyte layer 3, a graphite silver paste layer 4, a hydrophobic moisture-proof layer 5, an epoxy resin shell 7, a lead frame, a positive electrode lead and a negative electrode lead; wherein,

[0034] The outside of the tantalum anode 1 is covered with a dielectric layer 2, a solid electrolyte layer 3 and a graphite silver paste layer 4 in sequence from the inside to the outside;

[0035] The graphite silver paste layer 4 is bonded to the lead frame by conductive adhesive to lead out the positive electrode lead and the negative electrode lead;

[0036] The graphite silver paste layer 4 is coated with a hydrophobic moisture-proof layer 5;

[0037] The hydrophobic moisture-proof layer 5 is coated with an epoxy resin shell 7 .

[0038] Preferably, in the above tantalum capacitor, the thickness of the hydrophobic moisture-proof layer 5 is 0.1 μm to 50 μm. This thickness of the hydrophobic moisture-proof layer can ensure the moisture-proof performance of the chip-type solid electrolyte tantalum capacitor without increasing the difficulty of the preparation process and the volume and cost of the finished tantalum capacitor.

[0039] Preferably, in the above tantalum capacitor, the hydrophobic moisture-proof layer 5 is a film layer made of a hydrophobic elastomer material as a moisture-proof material. Preferably, the hydrophobic elastomer material is one material selected from silicone, fluorine-containing polymer, polyacrylate, polyurethane, and polyvinyl siloxane, or a mixture of several materials in any proportion.

[0040] like Figure 2 As shown, the embodiment of the present invention also provides a method for preparing the above-mentioned chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance, comprising the following steps:

[0041] Step 1, preparing a tantalum anode: using tantalum powder with a predetermined specific volume and parameters, making a tantalum block according to a predetermined pressing density, and sintering it at a predetermined heating rate within a sintering temperature range to form a tantalum anode block with a predetermined mechanical strength as a tantalum anode;

[0042] Step 2, preparing a dielectric layer: forming a dielectric layer of desired thickness on the tantalum anode prepared in step 1 in an acid-containing anodizing solution;

[0043] Step 3, preparing a solid electrolyte layer: covering the dielectric layer obtained in step 2 with a conductive polymer in situ or in the form of a dispersion after prepolymerization to obtain a solid electrolyte layer of desired thickness;

[0044] Step 4, preparing a graphite silver paste layer: coating a graphite and silver paste layer on the solid electrolyte layer obtained in step 3 to obtain a graphite silver paste layer as a cathode lead-out transition layer;

[0045] Step 5, preparing a hydrophobic moisture-proof layer: bonding the tantalum anode coated with the graphite silver paste layer in step 4 to the lead frame through a conductive adhesive, impregnating the moisture-proof material 1 to 10 times, and thermally curing at 110° C. to 160° C. for 10 min to 60 min to form a hydrophobic moisture-proof layer of a predetermined thickness outside the graphite silver paste layer;

[0046] Step 6, encapsulate the epoxy resin shell:

[0047] The product covered with the moisture-proof layer is encapsulated by injection molding epoxy resin on the outside of the product to form an epoxy resin shell.

[0048] Preferably, in step 5 of the above preparation method, the thickness of the prepared hydrophobic moisture-proof layer is 0.1 μm to 50 μm.

[0049] Preferably, in step 5 of the above preparation method, the moisture-proof material is a hydrophobic elastomeric material. The hydrophobic elastomeric material is preferably one material selected from silicone, fluorine-containing polymer, polyacrylate, polyurethane, and polyvinyl siloxane, or a mixture of several materials in any proportion.

[0050] In summary, it can be seen that the chip-type solid electrolyte tantalum capacitor of the embodiment of the present invention can prevent water vapor from penetrating into the interior of the tantalum capacitor by coating the graphite silver paste layer with a hydrophobic moisture-proof layer, thereby avoiding the degradation of internal organic materials and the deterioration of electrical parameters of the tantalum capacitor. Without increasing the difficulty of the preparation process and the volume and cost of the finished capacitor, the moisture-proof performance of the chip-type solid electrolyte tantalum capacitor is guaranteed, and the problems of poor moisture-proof performance of existing tantalum capacitors, deterioration of electrical performance after absorbing water vapor, and cracking of the epoxy shell during high-temperature welding are solved.

[0051] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the solution provided by the embodiment of the present invention is described in detail with specific embodiments below.

[0052] Example 1

[0053] The embodiment of the present invention provides a chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance, and its structure is as follows Figure 1 As shown, the preparation method of the chip-type solid electrolyte tantalum capacitor is as follows Figure 2 As shown, the following steps are included:

[0054] Step 1) Preparation of tantalum anode 1:

[0055] Use tantalum powder with a specific capacitance of 5000μF*V / g to 100000μF*V / g and a parameter of 5.0g / cm 3 ~8.0g / cm 3 A tantalum block is made of a suitable pressing density, and the tantalum block is sintered into a tantalum anode block with a certain mechanical strength at a heating rate range of 20°C / min to 100°C / min and a temperature range of 1300°C to 1800°C, as a block tantalum anode.

[0056] Step 2) preparing dielectric layer 2:

[0057] The tantalum anode 1 is in an anodic oxidation solution containing an acid (phosphoric acid or nitric acid), the solution mass ratio is 0.01wt% to 1wt%, the solution temperature is 60°C to 90°C, the current density is 5mA / g to 50mA / g, and the power supply initially reaches the desired formation voltage under constant current conditions. Thereafter, the power supply forms a dielectric layer 2 of a certain desired thickness under constant voltage conditions.

[0058] Step 3) Preparation of solid electrolyte layer 3:

[0059] The conductive polymer on the dielectric layer 2 can be covered in situ or in the form of a dispersion after prepolymerization. The in-situ polymerization oxidant and the organic monomer are impregnated 5 to 20 times, and the dispersion is impregnated 5 to 20 times. The thermal curing conditions are 100°C to 180°C and the time is 5min to 30min. The desired thickness of the solid electrolyte layer is achieved through multiple impregnations.

[0060] Step 4) preparing graphite silver paste layer 4:

[0061] The solid electrolyte 3 is coated with a graphite and silver paste layer to serve as a cathode lead-out transition layer.

[0062] Step 5) preparing a hydrophobic moisture-proof layer 5:

[0063] The product coated with the graphite silver paste layer 4 is bonded to the lead frame 6 by conductive adhesive, and then impregnated with a moisture-proof material 1 to 10 times. The moisture-proof material is usually composed of a hydrophobic elastomer, such as one or more of silicone, fluoropolymer, polyacrylate, polyurethane, and polyvinyl siloxane mixed in any proportion. The thermal curing conditions are 110°C to 160°C and the time is 10min to 60min to achieve the desired moisture-proof layer thickness of 0.1μm to 50μm.

[0064] Step 6) Encapsulating epoxy resin shell 7:

[0065] The product covered with the moisture-proof layer 5 is encapsulated by injecting epoxy resin on the outside of the product through high-temperature molding.

[0066] Example 2

[0067] This embodiment provides a method for preparing a chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance, which is used to prepare a solid electrolyte tantalum capacitor used in a high temperature and high humidity environment. The example specification of the solid electrolyte tantalum capacitor used in a high temperature and high humidity environment is 63V 47uF. The structure of the capacitor is as follows: Figure 1 The manufacturing process is shown in Figure 2 , the steps are as follows:

[0068] Step 1) Preparation of tantalum anode 1, using tantalum powder with a specific capacity of 23000uF.V / g, in a size of 5.0×5.20×2.60mm and a density of 7.0g / cm 3 The anode blank with tantalum wire lead wire is pressed into the design, and the pressed anode blank is subjected to high temperature vacuum sintering at 1450°C for 30 minutes, and passivation treatment is performed when it is taken out of the furnace after sintering to ensure that the number of folding of tantalum wire on the blank after sintering is not less than 4 times, and to ensure that the oxidation of tantalum block and tantalum wire is within an acceptable level;

[0069] Step 2) The tantalum anode 1 is coated with a dielectric layer 2, and the sintered tantalum anode 1 is spot welded to a stainless steel bar, which is then placed in a forming tank containing a mixed electrolyte of phosphoric acid and ethylene glycol at a temperature of 85°C and a resistivity of 800 to 1500Ω·cm (the phosphoric acid concentration in the electrolyte is 0.1% by volume, and the ethylene glycol concentration is 50% by volume), and the dielectric layer 2 is electrochemically formed at a forming voltage of 120V and a current density of 40mA / g.

[0070] Step 3) The solid electrolyte 3 is produced on the dielectric layer 2 by using an organic dispersion polymerization method. The main process is: immersing it in a dispersion of poly 3,4-ethylenedioxythiophene particles with a solid content of 3% and a particle size of 50 to 100 nm at a speed of 0.15 mm / s under vacuum for 5 minutes, and drying it at a vacuum environment of 50 to 150°C for 30 minutes. After that, the dried tantalum block is immersed in a cross-linking agent for 5 minutes and dried at 120°C for 20 minutes. This step is repeated alternately 10 times.

[0071] Step 4) The solid electrolyte layer 3 is coated with a graphite silver paste layer 4, and the tantalum anode 1 coated with the dielectric layer 2 and the solid electrolyte layer 3 is immersed in the hydrolyzed coupling agent solution for 10 min-2 h (the immersion process cannot be submerged to ensure that the solvent can enter the tantalum porous body), and then dried at 125 ° C for 10 min;

[0072] The tantalum block is then immersed in an oily graphite solution and a silver paste solution in turn, and then dried at 160°C / 30min to finally form a graphite layer and a silver paste layer, namely a graphite silver paste layer 4, which is mainly used for cathode lead-out.

[0073] Step 5) The tantalum block covered with the graphite silver paste layer 4 is first bonded to the lead frame 6 by conductive silver glue, and then immersed in a moisture-proof material under vacuum conditions, the immersion time is 90s, the heat treatment conditions are 150°C / 30min, and the number of immersions is 8 times, to generate a hydrophobic moisture-proof layer 5 that wraps the entire tantalum block.

[0074] The moisture-proof material is a mixture of one or more of polyacrylate, polyurethane and polyvinyl siloxane in any proportion.

[0075] Step 6) Encapsulate the epoxy resin shell 7 by molding, and encapsulate the epoxy resin layer outside the body to form the epoxy resin shell 7. The finished product has an outer size of 7.3mm×6.0mm×4.1mm, and then forms a complete finished product through printing, trimming, aging screening, etc.

[0076] The tantalum capacitor product prepared in the embodiment of the present invention and the tantalum capacitor product normally produced by the prior art are both subjected to a 125°C / 24h drying treatment, and after the electrical performance parameters are tested, they are placed in an environment under 85°C / 85% RH conditions for 168h. After being taken out, the electrical performance parameters are tested, and high-temperature welding is performed. The welding conditions are a peak temperature of 255°C and not less than 6s. After welding, the surface state of the epoxy resin shell 7 of the product is observed using a microscope.

[0077] The electrical performance results of the tantalum capacitor product prepared according to the embodiment of the present invention are unchanged, as shown in Table 1 and Table 2, and the epoxy resin shell has no cracking phenomenon. The ESR value of the product normally produced by the prior art increases by 120%, and cracking occurs on the surface of the epoxy resin shell.

[0078] Table 1 shows the electrical properties of existing chip solid electrolyte tantalum capacitor products

[0079]

[0080] Table 2 Electrical properties of chip-type solid electrolyte tantalum capacitor products of the present invention

[0081]

[0082]

[0083] In summary, it can be seen that the chip-type solid electrolyte tantalum capacitor in the embodiment of the present invention effectively improves the moisture-proof performance of the chip-type solid electrolyte tantalum capacitor by coating the graphite silver paste layer with a specific hydrophobic moisture-proof layer without increasing the difficulty, cost and volume of the preparation process, so that the chip-type solid electrolyte tantalum capacitor is suitable for use in high temperature and high humidity environments, ensuring product performance.

[0084] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance, characterized in that: include: Tantalum anode (1), dielectric layer (2), solid electrolyte layer (3), graphite silver paste layer (4), hydrophobic moisture-proof layer (5), epoxy resin shell (7), lead frame, positive electrode lead and negative electrode lead; wherein, The outside of the tantalum anode (1) is coated with a dielectric layer (2), a solid electrolyte layer (3) and a graphite silver paste layer (4) in sequence from the inside to the outside; The graphite silver paste layer (4) is bonded to the lead frame by conductive adhesive to lead out the positive electrode lead and the negative electrode lead; The graphite silver paste layer (4) is coated with a hydrophobic moisture-proof layer (5); The hydrophobic moisture-proof layer (5) is coated with an epoxy resin shell (7).

2. The chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance according to claim 1, characterized in that: The thickness of the hydrophobic moisture-proof layer (5) is 0.1 μm to 50 μm.

3. The chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance according to claim 1 or 2, characterized in that: The hydrophobic moisture-proof layer (5) is a thin film layer made of a hydrophobic elastic material as a moisture-proof material.

4. The chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance according to claim 3, characterized in that: The hydrophobic elastomer material is made of one material selected from the group consisting of organic silicon, fluorine-containing polymer, polyacrylate, polyurethane, and polyvinyl siloxane, or a mixture of several materials in any proportion.

5. A method for preparing a chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1, preparing a tantalum anode: using tantalum powder with a predetermined specific volume and parameters, making a tantalum block according to a predetermined pressing density, and sintering it at a predetermined heating rate within a sintering temperature range to form a tantalum anode block with a predetermined mechanical strength as a tantalum anode; Step 2, preparing a dielectric layer: forming a dielectric layer of desired thickness on the tantalum anode prepared in step 1 in an acid-containing anodizing solution; Step 3, preparing a solid electrolyte layer: covering the dielectric layer obtained in step 2 with a conductive polymer in situ or in the form of a dispersion after prepolymerization to obtain a solid electrolyte layer of desired thickness; Step 4, preparing a graphite silver paste layer: coating a graphite and silver paste layer on the solid electrolyte layer obtained in step 3 to obtain a graphite silver paste layer as a cathode lead-out transition layer; Step 5, preparing a hydrophobic moisture-proof layer: bonding the tantalum anode coated with the graphite silver paste layer in step 4 to the lead frame through a conductive adhesive, impregnating the moisture-proof material 1 to 10 times, and thermally curing at 110° C. to 160° C. for 10 min to 60 min to form a hydrophobic moisture-proof layer of a predetermined thickness outside the graphite silver paste layer; Step 6, encapsulate the epoxy resin shell: The product covered with the moisture-proof layer is encapsulated by injection molding epoxy resin on the outside of the product to form an epoxy resin shell.

6. The method for preparing a chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance according to claim 5, characterized in that: The thickness of the hydrophobic moisture-proof layer is 0.1 μm to 50 μm.

7. The method for preparing a chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance according to claim 5 or 6, characterized in that: In step 5, the moisture-proof material is a hydrophobic elastomer material.

8. The method for preparing a chip-type solid electrolyte tantalum capacitor with guaranteed moisture-proof performance according to claim 7, characterized in that: The hydrophobic elastic material is one material selected from the group consisting of organic silicon, fluorine-containing polymer, polyacrylate, polyurethane, and polyvinyl siloxane, or a mixture of several materials in any proportion.

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