CN114360911A - Method for preparing chip type solid electrolyte tantalum capacitor - Google Patents
Method for preparing chip type solid electrolyte tantalum capacitor Download PDFInfo
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- CN114360911A CN114360911A CN202111283666.9A CN202111283666A CN114360911A CN 114360911 A CN114360911 A CN 114360911A CN 202111283666 A CN202111283666 A CN 202111283666A CN 114360911 A CN114360911 A CN 114360911A
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- tantalum
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- sintering
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- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 title claims abstract description 136
- 229910052715 tantalum Inorganic materials 0.000 title claims abstract description 123
- 239000003990 capacitor Substances 0.000 title claims abstract description 41
- 238000000034 method Methods 0.000 title claims abstract description 37
- 239000007784 solid electrolyte Substances 0.000 title claims abstract description 29
- 238000005245 sintering Methods 0.000 claims abstract description 44
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims abstract description 33
- 239000002253 acid Substances 0.000 claims abstract description 32
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 238000010438 heat treatment Methods 0.000 claims abstract description 20
- 230000008569 process Effects 0.000 claims abstract description 18
- 239000008367 deionised water Substances 0.000 claims abstract description 13
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 13
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 12
- 238000000576 coating method Methods 0.000 claims abstract description 12
- 238000009835 boiling Methods 0.000 claims abstract description 10
- 239000011248 coating agent Substances 0.000 claims abstract description 10
- 239000000203 mixture Substances 0.000 claims abstract description 8
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 5
- 238000004806 packaging method and process Methods 0.000 claims abstract description 5
- 229910052709 silver Inorganic materials 0.000 claims abstract description 5
- 239000004332 silver Substances 0.000 claims abstract description 5
- 238000005406 washing Methods 0.000 claims abstract description 5
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 claims description 22
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 21
- 238000004519 manufacturing process Methods 0.000 claims description 13
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 12
- 150000003839 salts Chemical class 0.000 claims description 10
- 238000001514 detection method Methods 0.000 claims description 9
- 238000000354 decomposition reaction Methods 0.000 claims description 6
- 239000011812 mixed powder Substances 0.000 claims description 6
- 230000001502 supplementing effect Effects 0.000 claims description 6
- DSSYKIVIOFKYAU-XCBNKYQSSA-N (R)-camphor Chemical compound C1C[C@@]2(C)C(=O)C[C@@H]1C2(C)C DSSYKIVIOFKYAU-XCBNKYQSSA-N 0.000 claims description 5
- 241000723346 Cinnamomum camphora Species 0.000 claims description 5
- 229960000846 camphor Drugs 0.000 claims description 5
- 229930008380 camphor Natural products 0.000 claims description 5
- 238000002161 passivation Methods 0.000 claims description 5
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 4
- 229910019142 PO4 Inorganic materials 0.000 claims description 4
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 claims description 4
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 4
- 239000004327 boric acid Substances 0.000 claims description 4
- 239000010452 phosphate Substances 0.000 claims description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 4
- 238000003825 pressing Methods 0.000 claims description 4
- 239000001632 sodium acetate Substances 0.000 claims description 4
- 235000017281 sodium acetate Nutrition 0.000 claims description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 3
- 210000001061 forehead Anatomy 0.000 claims description 3
- DSSYKIVIOFKYAU-XVKPBYJWSA-N (1s,4r)-4,7,7-trimethylbicyclo[2.2.1]heptan-3-one Chemical compound C1C[C@@]2(C)C(=O)C[C@H]1C2(C)C DSSYKIVIOFKYAU-XVKPBYJWSA-N 0.000 claims description 2
- 238000001816 cooling Methods 0.000 claims description 2
- 238000007598 dipping method Methods 0.000 claims description 2
- 238000001035 drying Methods 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 239000002243 precursor Substances 0.000 claims description 2
- 239000008188 pellet Substances 0.000 claims 1
- 238000002360 preparation method Methods 0.000 abstract description 11
- 230000007547 defect Effects 0.000 abstract description 6
- 230000007774 longterm Effects 0.000 abstract description 6
- 239000000243 solution Substances 0.000 description 50
- 239000010410 layer Substances 0.000 description 44
- 239000000047 product Substances 0.000 description 8
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- 239000012535 impurity Substances 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 230000002829 reductive effect Effects 0.000 description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- -1 carrier Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000000306 component Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000013073 enabling process Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Inorganic materials O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
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- 238000005979 thermal decomposition reaction Methods 0.000 description 1
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Abstract
The invention discloses a preparation method of a chip type solid electrolyte tantalum capacitor, which comprises the following steps: sintering a tantalum block; boiling and washing the tantalum block; putting the tantalum block into an energizing solution consisting of phosphoric acid, ethylene glycol, deionized water and weak acid components for energizing, boosting the energizing voltage to 1.3 times of the preset energizing voltage in a constant-current boosting or constant-power boosting mode at room temperature, and keeping the constant voltage for 1-5 hours; raising the temperature to high temperature, keeping the voltage constant for 2-10 h according to preset energizing voltage; carrying out heat treatment on the tantalum block at the temperature of 300-500 ℃, wherein the tantalum block after heat treatment has a constant pressure for 1-4 h, and obtaining an energized anode tantalum block; wet detecting the leakage current of the anode tantalum block, and after the leakage current passes through the anode tantalum block, performing cathode treatment to form a structure body in which the anode tantalum block is coated by a cathode layer; and coating a buffer layer on the structure, coating a cathode lead-out silver paste layer, and packaging to obtain the chip solid electrolyte tantalum capacitor. By using the energizing solution and the energizing process with specific component compositions, the defects of the generated dielectric layer are fewer, the direct current leakage current value is smaller, and the long-term reliability of the product is better.
Description
Technical Field
The invention relates to the field of tantalum capacitors, in particular to a preparation method of a chip type solid electrolyte tantalum capacitor.
Background
Dielectric layer (Ta) of tantalum electrolytic capacitor2O5) The insulating properties and long term reliability are affected by many factors, including: tantalum powder characteristics (including impurity content, tantalum powder particle type), energizing process (energizing liquid type, current density, heat treatment conditions, energizing environment, and the like), coating process (high temperature stress), and the like. However, the characteristics of tantalum powder have been mainly determined in manufacturers, and stress generated by high temperature required for thermal decomposition of manganese nitrate in the coating process is indispensable. Therefore, the improvement of the enabling process becomes the most direct process means for optimizing the state of the dielectric layer.
In the existing dielectric layer formation, the adopted energizing process is simple, and the specific steps are as follows:
preparing energizing solution from nitric acid or phosphoric acid, ethylene glycol, deionized water and the like according to different proportions, wherein the resistivity of the energizing solution is 50-2000 omega cm, the temperature is different from 10-100 ℃, the energizing voltage is different from 16V-300V, then performing energizing treatment of first constant-current boosting and then constant-voltage current reduction, and completing the energizing of the tantalum core through the process.
However, the existing process for energizing the tantalum core has at least the following problems: (1) the low-voltage product (energized voltage is less than or equal to 120V) has the defects of weak water resistance, large leakage current change and the like if the low-voltage product is placed in a long-term humidity environment because the energized liquid mostly adopts nitric acid with the volume concentration of 0.1%; (2) the conventional energized solution has impurities, so that defect points formed by the impurities become key positions for crystal nucleus formation under high field intensity, and then large-area crystallization is gradually carried out, so that the leakage current of the product is increased and the failure rate is reduced; (3) due to the fact that the proportion of acid solution used in the preparation of the energizing solution is small, the set temperature of the solution is low and the like, the forming efficiency of the medium layer in the energizing process is relatively small, and therefore the production period is increased.
From the above description, it can be seen how to energize tantalum cores to obtain MnO with better insulation and higher long term reliability2The chip type solid electrolyte tantalum capacitor is a problem to be solved.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
Based on the problems in the prior art, the invention aims to provide a preparation method of a chip type solid electrolyte tantalum capacitor, which can increase the inherent reliability of the chip type solid electrolyte tantalum capacitor and further solve the problems of weak water resistance, large leakage current, long energizing time and the like in the existing dielectric layer forming process.
The purpose of the invention is realized by the following technical scheme:
the embodiment of the invention provides a preparation method of a chip type solid electrolyte tantalum capacitor, which comprises the following steps:
sintering the pressed tantalum blank into a tantalum block;
boiling and washing the tantalum block for 30min in boiling water;
taking a mixed solution consisting of phosphoric acid, ethylene glycol, deionized water and a weak acid component as an energizing solution, wherein the weak acid component adopts weak acid or weak acid salt, and the tantalum block is placed in the energizing solution to be energized according to the following steps:
step 21) boosting the energizing voltage to 1.3 times of the preset energizing voltage by adopting a constant current boosting or constant power boosting mode at room temperature, and then keeping the constant voltage for 1-5 h;
step 22) heating the energized solution to high temperature, and keeping the energized solution at constant voltage for 2-10 h according to preset energized voltage;
step 23) carrying out heat treatment on the tantalum block obtained in the step 22 at the temperature of 300-500 ℃, wherein the heat treatment time is 10-30 min, and the constant pressure of the tantalum block after heat treatment is 1-4 h under the original energized solution and a preset energized voltage, so as to obtain an energized anode tantalum block;
carrying out wet-type leakage current detection on the energized anode tantalum block, and carrying out cathode treatment on the anode tantalum block to form a structure body of which the cathode layer covers the anode tantalum block after the leakage current detection is passed;
and coating a buffer layer on the structure body of the anode tantalum block coated by the cathode layer, coating a cathode lead-out silver paste layer outside the buffer layer, and packaging to obtain the chip solid electrolyte tantalum capacitor.
According to the technical scheme provided by the invention, the preparation method of the chip type solid electrolyte tantalum capacitor provided by the embodiment of the invention has the following beneficial effects:
by adopting energizing solution consisting of specific components, heat treatment is matched at different temperatures and an energizing mode corresponding to current density is selected, the tantalum electrolytic capacitor with fewer defects, smaller leakage current, shorter energizing time and higher long-term reliability is prepared, and thus the service reliability and the service life of the tantalum electrolytic capacitor are ensured; due to the adoption of a relatively excellent dielectric layer forming process, the defects in the prior art, such as weak water resistance, large leakage current, long energizing time and the like, can be overcome, and the inherent reliability of the chip type solid electrolyte tantalum capacitor product is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 shows MnO provided in an embodiment of the present invention2A flow chart of a preparation method of the chip type solid electrolyte tantalum capacitor;
FIG. 2 is a scanning electron microscope image of a dielectric layer of an anode tantalum block after being energized according to the preparation method provided by the embodiment of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the specific contents of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention. Details which are not described in detail in the embodiments of the invention belong to the prior art which is known to the person skilled in the art.
The terms that may be used herein are first described as follows:
the term "and/or" means that either or both can be achieved, for example, X and/or Y means that both cases include "X" or "Y" as well as three cases including "X and Y".
The terms "comprising," "including," "containing," "having," or other similar terms of meaning should be construed as non-exclusive inclusions. For example: including a feature (e.g., material, component, ingredient, carrier, formulation, material, dimension, part, component, mechanism, device, process, procedure, method, reaction condition, processing condition, parameter, algorithm, signal, data, product, or article of manufacture), is to be construed as including not only the particular feature explicitly listed but also other features not explicitly listed as such which are known in the art.
The term "consisting of … …" is meant to exclude any technical feature elements not explicitly listed. If used in a claim, the term shall render the claim closed except for the inclusion of the technical features that are expressly listed except for the conventional impurities associated therewith. If the term occurs in only one clause of the claims, it is defined only to the elements explicitly recited in that clause, and elements recited in other clauses are not excluded from the overall claims.
The term "parts by mass" is intended to indicate a mass ratio relationship between a plurality of components, for example: if X component is X parts by mass and Y component is Y parts by mass, the mass ratio of the X component to the Y component is X: Y; 1 part by mass may represent any mass, for example: 1 part by mass may be expressed as 1kg or 3.1415926 kg. The sum of the parts by mass of all the components is not necessarily 100 parts, and may be more than 100 parts, less than 100 parts, or equal to 100 parts. Parts, ratios and percentages described herein are by mass unless otherwise indicated.
Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "secured," etc., are to be construed broadly, as for example: can be fixedly connected, can also be detachably connected or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms herein can be understood by those of ordinary skill in the art as appropriate.
When concentrations, temperatures, pressures, dimensions, or other parameters are expressed as ranges of values, the ranges are to be understood as specifically disclosing all ranges formed from any pair of upper, lower, and preferred values within the range, regardless of whether ranges are explicitly recited; for example, if a numerical range of "2 ~ 8" is recited, then the numerical range should be interpreted to include ranges of "2 ~ 7", "2 ~ 6", "5 ~ 7", "3 ~ 4 and 6 ~ 7", "3 ~ 5 and 7", "2 and 5 ~ 7", and the like. Unless otherwise indicated, the numerical ranges recited herein include both the endpoints thereof and all integers and fractions within the numerical range.
The terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like are used in an orientation or positional relationship that is indicated based on the orientation or positional relationship shown in the drawings for ease of description and simplicity of description only, and are not intended to imply or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting herein.
The method for manufacturing the chip-type solid electrolyte tantalum capacitor provided by the present invention is described in detail below. Details which are not described in detail in the embodiments of the invention belong to the prior art which is known to the person skilled in the art. Those not specifically mentioned in the examples of the present invention were carried out according to the conventional conditions in the art or conditions suggested by the manufacturer. The reagents or instruments used in the examples of the present invention are not specified by manufacturers, and are all conventional products available by commercial purchase.
Referring to fig. 1, an embodiment of the present invention provides a method for manufacturing a chip-type solid electrolyte tantalum capacitor, including:
sintering the pressed tantalum blank into a tantalum block;
boiling and washing the tantalum block for 30min in boiling water; preferably, the boiling water is deionized water at 100 ℃;
taking a mixed solution consisting of phosphoric acid, ethylene glycol, deionized water and a weak acid component as an energizing solution, wherein the weak acid component adopts weak acid or weak acid salt, and the tantalum block is placed in the energizing solution to be energized according to the following steps:
step 21) boosting the energizing voltage to 1.3 times of the preset energizing voltage by adopting a constant current boosting or constant power boosting mode at room temperature, and then keeping the constant voltage for 1-5 h;
step 22) heating the energized solution to high temperature, and keeping the energized solution at constant voltage for 2-10 h according to preset energized voltage;
step 23) carrying out heat treatment on the tantalum block obtained in the step 22 at the temperature of 300-500 ℃, wherein the heat treatment time is 10-30 min, and the energized anode tantalum block is obtained after heat treatment;
carrying out wet detection leakage current on the energized anode tantalum block, and carrying out cathode treatment on the anode tantalum block to form a structure body of which the cathode layer covers the anode tantalum block after the detection is passed;
and coating a buffer layer on the structure body of the anode tantalum block coated by the cathode layer, coating a cathode lead-out silver paste layer outside the buffer layer, and packaging to obtain the chip solid electrolyte tantalum capacitor.
In the method, the pressed tantalum billet is as follows: selecting a specific volume B corresponding to the voltage of the capacitorsAdding camphor into the tantalum powder, and uniformly mixing to form mixed powderDrying the mixed powder, and pressing into tantalum blanks with corresponding sizes, wherein the camphor is a mixture of camphor powder and absolute ethyl alcohol;
sintering the pressed tantalum billet into a tantalum block by three-stage sintering, comprising:
the first stage sintering is sintering from room temperature to 1000 ℃, and the temperature rise speed is 20 ℃/min to 100 ℃/min;
the second stage sintering is sintering at 1000-1450 ℃ with the heating rate of 20-100 ℃/min;
the third stage of sintering is sintering at any temperature between 1500 ℃ and 1800 ℃ (the sintering temperature in the third stage is preferably any temperature of 1550 ℃, 1600 ℃, 1650 ℃, 1700 ℃ and 1800 ℃) for 20-40 min at constant temperature;
after the sintering, the temperature is reduced to 400 ℃ from any temperature between 1500 ℃ and 1800 ℃ (the sintering temperature in the section is preferably any temperature of 1550 ℃, 1600 ℃, 1650 ℃, 1700 ℃ and 1800 ℃), the temperature is kept for 20-60 min, then the temperature is continuously cooled to the room temperature, air is gradually introduced for passivation, and the passivation time is 2-12 hours.
In the method, in the three-stage sintering, the temperature rising speed of the first stage sintering is 20 ℃/min;
the temperature rise rate of the second stage sintering is 40 ℃/min.
In the energization process of the above method, the predetermined energization voltage UfBy the formula Uf＝K×Bs×M/CForehead (forehead)Calculating to obtain K which is a proportional coefficient determined according to the sintering shrinkage and the pressing density;
in the step 21, the room temperature is 10-45 ℃;
in the step 22, the high temperature is 55-95 ℃.
In the energizing solution of the method, the phosphoric acid accounts for 0.1-2% of the total volume of the energizing solution;
the ethylene glycol accounts for 9% -90% of the total volume of the energized solution;
the deionized water accounts for 9% -90% of the total volume of the energized solution;
the weak acid component accounts for 0.01-1% of the total volume of the energized solution.
In the energizing solution, the weak acid component is weak acid or weak acid salt, or a mixture of weak acid and weak acid salt.
In the energized solution, the weak acid is any one of citric acid, boric acid and acetic acid;
the weak acid salt is any one of phosphate, borate and sodium acetate;
the mixture of weak acid and weak acid salt is: any two or more of citric acid, boric acid, acetic acid, phosphate, borate and sodium acetate. The weak acid component is added to play a role in inhibiting crystallization and improve the pressure resistance of the dielectric layer.
In the energized solution, the current density of the constant current boosting is as follows: 1 mA/g-150 mA/g. Preferably, a current density of 5mA/g to 100mA/g is used. When energized in the current density range, a dielectric layer with fewer crystallization points and better pressure resistance can be formed.
In the above method, cathodically treating the anode tantalum block to form a structure in which the anode tantalum block is coated with a cathode layer comprises:
manganese nitrate solution with the concentration of 1.10 g/ml-1.80 g/ml is adopted as the precursor solution of the cathode layer;
and repeatedly immersing the anode tantalum block in the manganese nitrate solution for 10 times to decompose, supplementing the manganese nitrate solution for 20min according to 1/2 times of a preset energizing voltage after the decomposition, immersing the anode tantalum block in the manganese nitrate solution for 6 times to decompose, supplementing the manganese nitrate solution for 10min according to 1/2 times of the preset energizing voltage, and forming the structure body of the anode tantalum block coated by the cathode layer after the treatment.
In the method, the anode tantalum block is repeatedly immersed in the manganese nitrate solution for 10 times of decomposition, and the concentration of the manganese nitrate solution is 1.30 g/ml; because the concentration of the manganese nitrate solution of 1.30g/ml is relatively low, MnO which can permeate into the inner part of the anode tantalum block and be decomposed can be obtained2The coverage area on the dielectric layer is larger and more compact, and finally the cathode extraction rate is higher.
The manganese nitrate solution used for decomposing 6 times by dipping the manganese nitrate solution again has the concentration of 1.58 g/ml. Impregnating the solution to makeFaster growth of MnO of thickness on the outer surface of the anode tantalum block2And the layer effectively prevents the breakdown phenomenon caused by point discharge.
Preferably, in the energizing process, the energizing solution is phosphoric acid, ethylene glycol, deionized water and citric acid, and the temperature of the energizing liquid chamber is 30 +/-10 ℃; the high temperature of the energized solution was 85 ℃. + -. 5 ℃.
MnO of the present invention2Due to the advantages of the specific energizing solution, the preparation method of the chip type solid electrolyte tantalum capacitor enables the formed anode tantalum block to have a good dielectric layer, avoids the problem of increased leakage current in subsequent use caused by dielectric layer defects, and improves the use reliability and service life of the high-voltage tantalum electrolytic capacitor.
The embodiments of the present invention are described in further detail below.
Example 1
Referring to fig. 1, in this embodiment, a flow of the preparation method of the present invention is illustrated by taking an E-shell tantalum electrolytic capacitor product of 50V15 μ F as an example, and includes:
firstly, tantalum powder with STA180 as tantalum powder is selected to be uniformly mixed with 2 percent (mass percentage) of camphor (anhydrous ethanol mixed powder), and after the mixed powder is dried, the mixed powder is pressed into a tantalum blank with the size of 3.50mm multiplied by 3.00mm multiplied by 3.30mm and the powder amount M of 201 mg;
performing three-stage sintering on the tantalum blank:
the first stage sintering is sintering from room temperature to 1000 ℃, and the temperature rise speed is 20 ℃/min;
the second stage sintering is sintering at 1000-1450 ℃ with the heating rate of 40 ℃/min;
the third stage of sintering is sintering at the constant temperature of 1500 ℃ for 20-40 min;
after the sintering, the temperature is reduced from 1500 ℃ to 400 ℃, the temperature is kept for 30min, then the cooling is continued to the room temperature, air is gradually introduced for passivation, and the passivation time is 4 hours.
After sintering, obtaining a tantalum block with certain strength (as shown in figure 2), energizing the tantalum block after sintering, and calculating a preset energizing voltage Uf，Uf＝M×15000μF*V/g÷CForehead (forehead)≈200V；
Wherein 15000 muF V/g is the specific volume of the tantalum powder STA180 at about 200V. The energizing solution is a mixed solution of phosphoric acid, ethylene glycol, deionized water and citric acid, and the mixed solution comprises the following components in percentage by weight: 100ml of phosphoric acid, 13L of ethylene glycol, 37L of deionized water and 60ml of citric acid; the enabling mode is as follows: boosting the voltage to 1.3 times of the preset energized voltage at room temperature (less than or equal to 45 ℃) with the current density of 30mA/g, and keeping the voltage constant for 3 hours; then increasing the current density to energized voltage at 85 +/-5 ℃ according to 15mA/g, and then keeping the voltage constant for 2 hours; then boiling and washing the energized anode tantalum block in boiling water (deionized water at 100 ℃) for 30min, then carrying out heat treatment in a drying oven at 400 ℃ for 15min, and finally carrying out constant voltage for 2 hours under the original energized solution and preset energized voltage to obtain the anode tantalum block with the dielectric layer with uniform thickness;
performing wet detection on the leakage current of the anode tantalum block with the dielectric layer with uniform thickness obtained after energization, wherein a 10% Wt phosphoric acid solution is adopted as a wet detection solution, and the test voltage is a predetermined energization voltage which is 0.7 times; the leakage current of the anode tantalum blocks of the 50V tantalum capacitor and the 63V tantalum capacitor manufactured in the energizing manner is detected in a wet mode, and if the leakage current of the anode tantalum blocks produced by the general energizing process is about 1/3, the qualified anode tantalum blocks are obtained;
performing cathode forming treatment on the energized anode tantalum block, repeatedly immersing the anode tantalum block in a manganese nitrate solution with the concentration of 1.30g/ml for decomposition for 10 times, supplementing the solution according to 1/2 times of a preset energizing voltage for 20min after the decomposition is finished, immersing the anode tantalum block in the manganese nitrate solution with the concentration of 1.58g/ml for decomposition for 6 times, and finally supplementing the solution according to 1/2 times of the preset energizing voltage for 30min to obtain a structure of the anode tantalum block wrapped by the cathode layer;
coating a buffer layer (namely a graphite layer) on a structure body of which the cathode layer wraps the anode tantalum block, coating a cathode lead-out silver paste layer on the outer layer, and then carrying out subsequent packaging treatment according to the flow in the figure 1 to prepare the finished product of the high-voltage chip type solid electrolyte tantalum capacitor. In the manufactured tantalum capacitor, the outer surface of the tantalum block of the anode tantalum block is a dielectric layer, and MnO is arranged outside the dielectric layer2Electrolyte layer, MnO2The electrolyte layer is used as a cathode layer, and the electrolyte layer and the cathode layer are encapsulated in the epoxy resin protective layer and are led out from the cathode through the lead frame,the anode is led out by connecting a tantalum wire with an anode tantalum block, and a polytetrafluoroethylene pad is arranged at the joint of the tantalum wire and the anode tantalum block.
Comparative examples
The core of this example was prepared in a similar manner to example 1, with reference to example 1, except that the energizing process of this example was: the energizing solution was a mixed solution of 50ml of phosphoric acid, 20L of ethylene glycol and 30L of deionized water, a constant current at a current density of 30mA/g was selected at 85 ℃ to raise the voltage to a predetermined energizing voltage, and then a constant voltage was applied for 5 hours, after which the same operation as in example 1 was carried out, and finally a capacitor was produced.
Comparison of the wet leakage current values of example 1 and comparative example:
TABLE 1 comparison table for wet-type detection of leakage current
It can be seen from the comparison that by adopting the novel energizing process of the preparation method, a dielectric layer with a good micro-morphology is formed on the surface of the anode tantalum, fig. 2 is a comparison graph before and after improvement, fig. 2a in fig. 2 is a dielectric layer morphology graph formed by the prior energizing process, and fig. 2b is a dielectric layer morphology graph formed by adopting the novel energizing process of the invention, so that the characteristics of reducing leakage current, shortening energizing period and the like are realized, and meanwhile, the long-term reliability is improved.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. A method for preparing a chip type solid electrolyte tantalum capacitor is characterized by comprising the following steps:
sintering the pressed tantalum blank into a tantalum block;
boiling and washing the tantalum block for 30min in boiling water;
placing the tantalum block into an energizing solution composed of phosphoric acid, ethylene glycol, deionized water and a weak acid component as the energizing solution, and energizing according to the following steps:
step 21) boosting the energizing voltage to 1.3 times of the preset energizing voltage by adopting a constant current boosting or constant power boosting mode at room temperature, and then keeping the constant voltage for 1-5 h;
step 22) heating the energized solution to high temperature, and keeping the energized solution at constant voltage for 2-10 h according to preset energized voltage;
step 23) carrying out heat treatment on the tantalum block obtained in the step 22 at the temperature of 300-500 ℃, wherein the heat treatment time is 10-30 min, and the constant pressure of the tantalum block after heat treatment is 1-4 h under the original energized solution and a preset energized voltage, so as to obtain an energized anode tantalum block;
carrying out wet-type leakage current detection on the energized anode tantalum block, and carrying out cathode treatment on the anode tantalum block to form a structure body of which the cathode layer covers the anode tantalum block after the leakage current detection is passed;
and coating a buffer layer on the structure body of the anode tantalum block coated by the cathode layer, coating a cathode lead-out silver paste layer outside the buffer layer, and packaging to obtain the chip solid electrolyte tantalum capacitor.
2. The method for manufacturing a chip solid electrolyte tantalum capacitor according to claim 1, wherein the pressed tantalum pellet is: selecting a specific volume B corresponding to the voltage of the capacitorsAdding camphor into the tantalum powder, uniformly mixing to form mixed powder, drying the mixed powder, and pressing into tantalum blanks with corresponding sizes, wherein the camphor is a mixture of camphor powder and absolute ethyl alcohol;
sintering the pressed tantalum billet into a tantalum block by three-stage sintering, comprising:
the first stage sintering is sintering from room temperature to 1000 ℃, and the temperature rise speed is 20 ℃/min to 100 ℃/min;
the second stage sintering is sintering at 1000-1450 ℃ with the heating rate of 20-100 ℃/min;
the third stage of sintering is constant temperature sintering at any temperature of 1500-1800 ℃ for 20-40 min;
and after sintering, reducing the temperature from any temperature of 1500-1800 ℃ to 400 ℃, preserving the heat for 20-60 min, then continuously cooling to room temperature, and gradually introducing air for passivation for 2-12 hours.
3. The method for producing a chip solid electrolyte tantalum capacitor according to claim 2, wherein in the three-stage sintering, the temperature rise rate in the first stage sintering is 20 ℃/min;
the temperature rise speed of the second-stage sintering is 40 ℃/min;
the third stage sintering temperature is preferably: any one temperature of 1550 ℃, 1600 ℃, 1650 ℃, 1700 ℃ and 1800 ℃;
the sintering temperature from any temperature between 1500 ℃ and 1800 ℃ down to 400 ℃ is preferably: 1550 deg.C, 1600 deg.C, 1650 deg.C, 1700 deg.C, 1800 deg.C.
4. The production method for a chip solid electrolyte tantalum capacitor according to any one of claims 1 to 3, wherein a predetermined energization voltage U is used in the energization process of the methodfBy the formula Uf＝K×Bs×M/CForehead (forehead)Calculating to obtain K which is a proportional coefficient determined according to the sintering shrinkage and the pressing density;
in the step 21, the room temperature is 10-45 ℃;
in the step 22, the high temperature is 55-95 ℃.
5. The method for producing a chip solid electrolyte tantalum capacitor according to any one of claims 1 to 3, wherein said phosphoric acid is contained in said energizing solution in an amount of 0.1 to 2% by volume based on the total volume of the energizing solution;
the ethylene glycol accounts for 9% -90% of the total volume of the energized solution;
the deionized water accounts for 9% -90% of the total volume of the energized solution;
the weak acid component accounts for 0.01-1% of the total volume of the energized solution.
6. The method for manufacturing a chip solid electrolyte tantalum capacitor as claimed in claim 5, wherein said weak acid component is a weak acid or a weak acid salt, or a mixture of a weak acid and a weak acid salt.
7. The method for manufacturing a chip solid electrolyte tantalum capacitor according to claim 4, wherein said weak acid is any one of citric acid, boric acid and acetic acid;
the weak acid salt is any one of phosphate, borate and sodium acetate;
the mixture of weak acid and weak acid salt is: any two or more of citric acid, boric acid, acetic acid, phosphate, borate and sodium acetate.
8. The production method of a chip solid electrolyte tantalum capacitor according to any one of claims 1 to 3, wherein the constant current and voltage boosting current density is: 1 mA/g-150 mA/g.
9. The method for manufacturing a chip solid electrolyte tantalum capacitor according to any one of claims 1 to 3, wherein the anode tantalum block is cathodically processed to form a structure in which the anode tantalum block is coated with a cathode layer by:
manganese nitrate solution with the concentration of 1.10 g/ml-1.80 g/ml is adopted as the precursor solution of the cathode layer;
and repeatedly immersing the anode tantalum block in the manganese nitrate solution for 10 times to decompose, supplementing the manganese nitrate solution for 20min according to 1/2 times of a preset energizing voltage after the decomposition, immersing the anode tantalum block in the manganese nitrate solution for 6 times to decompose, supplementing the manganese nitrate solution for 10min according to 1/2 times of the preset energizing voltage, and forming the structure body of the anode tantalum block coated by the cathode layer after the treatment.
10. The method for manufacturing a chip solid electrolyte tantalum capacitor according to claim 9, wherein the concentration of manganese nitrate solution used for repeatedly immersing said anode tantalum block in said manganese nitrate solution to decompose 10 times is 1.30 g/ml;
the manganese nitrate solution used for decomposing 6 times by dipping the manganese nitrate solution again has the concentration of 1.58 g/ml.
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| CN115223798A (en) * | 2022-07-29 | 2022-10-21 | 长春维鸿东光电子器材有限公司 | Manufacturing method of axially-led organic polymer tantalum fixed capacitor |
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| CN105810459A (en) * | 2016-04-05 | 2016-07-27 | 电子科技大学 | Energizing process for preventing positive electrode crystallization of tantalum capacitor |
| CN105977030A (en) * | 2016-06-14 | 2016-09-28 | 东莞市联洲知识产权运营管理有限公司 | Preparation method for ultra-high-capacity tantalum capacitor |
| CN106057468A (en) * | 2016-06-14 | 2016-10-26 | 东莞市联洲知识产权运营管理有限公司 | Preparation process of chip type niobium electrolytic capacitor |
| CN111696786A (en) * | 2020-05-19 | 2020-09-22 | 北京七一八友益电子有限责任公司 | Preparation method of high-voltage chip type solid electrolyte tantalum capacitor |
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| CN105810459A (en) * | 2016-04-05 | 2016-07-27 | 电子科技大学 | Energizing process for preventing positive electrode crystallization of tantalum capacitor |
| CN105977030A (en) * | 2016-06-14 | 2016-09-28 | 东莞市联洲知识产权运营管理有限公司 | Preparation method for ultra-high-capacity tantalum capacitor |
| CN106057468A (en) * | 2016-06-14 | 2016-10-26 | 东莞市联洲知识产权运营管理有限公司 | Preparation process of chip type niobium electrolytic capacitor |
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