High-reliability mica capacitor with completely monolithic end and preparation method thereof

Abstract

The application belongs to the field of capacitors, and particularly relates to a high-reliability mica capacitor with a completely monolithic structure and a preparation method thereof. The preparation method comprises the following steps: S1, first, mica powder is pretreated and intercalated to obtain two-dimensional nanometer mica, and then the two-dimensional nanometer mica is surface-modified by using aminoboron nitride, and after being pressed, dried and cut, a surface-modified mica sheet is obtained; S2, silver electrode layers are symmetrically printed on two surfaces of the surface-modified mica sheet by using silk screen printing, and then the surface-modified mica sheet is placed on a heating flat plate to be dried, and then is transferred to a tunnel sintering furnace to be calcined, so that a mica silver sheet is obtained; S3, the mica silver sheet is laminated and assembled, and then is placed in a high-temperature box furnace to be sintered, so that a sintered core group is obtained; and S4, the sintered core group is coated with silver at the end by using silver paste, and is dried, so that the high-reliability mica capacitor with a completely monolithic structure is obtained. The capacitor has good flame retardance and can withstand high temperature.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of capacitors, and particularly relates to a high-reliability mica capacitor with a completely monolithic end structure and a preparation method thereof. BACKGROUND

[0002] With the development of electronic information technology, electronic components gradually develop towards miniaturization, light weight, integration and high performance. As one of the basic important components in electronic components, capacitors account for a large proportion in passive components, and almost all electronic devices need to be configured with capacitors on a large scale. Capacitors store and release electrical energy in the form of static electricity, isolate the electrical energy between two conductive substances with a medium, and store the electrical energy therebetween, mainly playing the roles of charge storage, AC filtering or bypass, DC cutoff or blocking, providing tuning and oscillation, etc. According to the different types of media, capacitors mainly include mica capacitors, porcelain dielectric capacitors, glass enamel capacitors, electrolytic capacitors, paper dielectric capacitors, and thin film capacitors.

[0003] Mica capacitors are capacitors that use mica as the intermediate dielectric. They are mostly square in shape and have excellent high-voltage performance. Their working principle is based on the storage and release of electric charge. When the capacitor is in the charging state, the ions in the electrolyte will be attracted to the electrode under the action of the electric field, forming positive and negative charges. When the capacitor is in the discharging state, the stored electric charge will be released and flow back into the electrolyte. Mica capacitors have excellent electrical performance and stable physical properties, with low dielectric loss, high voltage strength, good capacity temperature and time stability, excellent high-frequency characteristics, high precision, and good heat resistance, and are widely used in various high-precision equipment and instrument industries in the fields of communication, electronics, power, aerospace, aviation, navigation, satellite electronics, etc.

[0004] Chinese patent (publication number CN115483025B) discloses a preparation process for mica sheet capacitors. The specific operation method includes the following steps: mica sheet selection and peeling: selecting and trimming thick mica sheets, then peeling the selected thick mica sheets with a peeling knife, and classifying the peeled mica sheets according to thickness; mica sheet thickness classification: classifying the thin mica sheets in the above step according to thickness with a micrometer. The invention uses green, pollution-free raw materials for silver paste preparation, which is low in production cost. After coating the silver paste on the mica sheet and performing silver printing and infiltration, the produced products are tested for voltage resistance, insulation resistance, loss tangent, capacitor temperature coefficient, and capacity stability, which can effectively avoid the defective rate of the products. However, this technology lacks research on the thermal stability and flame retardancy of mica capacitors, and cannot guarantee the reliability of the capacitors to meet the requirements.

[0005] Therefore, there is an urgent need for a mica capacitor with a completely monolithic structure, which improves the thermal stability of the capacitor by designing the mica and silver paste material, while ensuring good flame retardant performance, thereby realizing high reliability. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a high-reliability mica capacitor with a completely monolithic structure and a preparation method thereof. The present application uses a liquid-phase assisted ultrasonic exfoliation method to process mica powder in multiple steps to obtain two-dimensional nanometer mica, and cooperates with the surface modification of aminated boron nitride to process into a surface-modified mica sheet. Based on the surface-modified mica sheet, a high-reliability mica capacitor with a completely monolithic structure is obtained through multiple process treatments, which not only ensures good thermal stability, but also improves the flame retardant performance.

[0007] In a first aspect of the present application, a preparation method of a high-reliability mica capacitor with a completely monolithic structure is provided, comprising the following steps:

[0008] S1, first pretreat mica powder to obtain pretreated mica powder; intercalate the pretreated mica powder to obtain two-dimensional nanometer mica; use aminated boron nitride to modify the surface of the two-dimensional nanometer mica to obtain a mixture; press, dry and cut the mixture to obtain a surface-modified mica sheet;

[0009] S2, symmetrically print silver electrode layers on both sides of the surface-modified mica sheet by silk screen printing, then place it on a heating flat plate for drying, and then transfer it to a tunnel sintering furnace for calcination to obtain a mica silver sheet;

[0010] S3, stack and assemble the mica silver sheet, then place it in a high-temperature box furnace for sintering to obtain a sintered core group;

[0011] S4, use silver paste to coat the end of the sintered core group, dry it, and obtain a high-reliability mica capacitor with a completely monolithic structure.

[0012] As a preferred technical solution of the present application, the pretreatment step is as follows: 10-20 parts by weight of mica powder are kept at 750-800 DEG C for 60-80 min, then transferred to 400-600 parts of 5mol / L nitric acid solution, stirred at 85-95 DEG C for 5-7 h, washed with water to neutral, dried to obtain acid-treated mica powder; 10-20 parts of the acid-treated mica powder are added to 400-600 parts of 1mol / L sodium chloride solution, stirred at 80-90 DEG C for 4-6 h, washed with water and dried to obtain pretreated mica powder.

[0013] As a preferred technical scheme of the present application, the step of intercalation treatment is: 40-50 parts of cetyltrimethylammonium bromide is dissolved in 900-1000 parts of deionized water, then 15-25 parts of the pretreated mica powder is added, heated to 80-90 DEG C and stirred for 20-24 hours, centrifuged, the solid is washed with water and dried, then dispersed in 400-500 parts of anhydrous ethanol, ultrasonic broken for 30-40 minutes, centrifuged to obtain the supernatant containing two-dimensional nanometer mica, vacuum dried to obtain two-dimensional nanometer mica.

[0014] As a preferred technical scheme of the present application, the preparation step of the aminated boron nitride is: 6-8 parts of boron nitride, 180-200 parts of urea and 10-20 parts of deionized water are mixed and ground at a speed of 20-30 r / min for 12-16 hours, then transferred to 400-500 parts of deionized water and stirred for 20-30 minutes, filtered, and the filter residue is dried to obtain the aminated boron nitride.

[0015] The aminated boron nitride of the present application uses boron nitride and urea as raw materials, and generates a transverse shear force in the grinding process, so that the boron nitride sheet layer is continuously peeled and thinned with the assistance of urea, the urea wrapped on the surface of boron nitride reacts with B-N bond to form a new chemical bond, thereby realizing surface modification while peeling, and obtaining the aminated boron nitride.

[0016] As a preferred technical scheme of the present application, the step of surface modification is: 4-6 parts of two-dimensional nanometer mica is dispersed in 400-600 parts of deionized water, then 0.4-0.6 parts of aminated boron nitride and 0.3-0.5 parts of sodium chloride are added, stirred at 60-70 DEG C for 1-2 hours, and vacuum dried to obtain a mixture.

[0017] As a preferred technical scheme of the present application, the preparation step of the surface modified mica sheet is: the mixture is pressed, dried at 85 DEG C, and cut into a surface modified mica sheet with an area of 1*1 m 2 , and a thickness of 500 microns.

[0018] The present application uses liquid phase assisted ultrasonic peeling method to pretreat the mica powder, including heat activation, acid treatment, and salt washing, then uses a cationic surfactant for intercalation and ultrasonic peeling, and finally obtains two-dimensional nanometer mica; then the two-dimensional nanometer mica is surface modified by aminated boron nitride, the amino group of boron nitride is tightly connected with the two-dimensional nanometer mica through hydrogen bond and electrostatic interaction, and finally is processed into a surface modified mica sheet.

[0019] As a preferred technical scheme of the present application, the preparation method of the silver paste is as follows: 80-90 parts of silver powder and 4-8 parts of glass powder are added into 20-30 parts of solvent to mix and then high-speed dispersed, and then transferred into a three-roll mill to grind, to obtain the silver paste.

[0020] As a preferred technical scheme of the present application, the silver powder is nano silver powder and hybrid silver particles; and the mass ratio of the nano silver powder and the hybrid silver particles is (2-3):1.

[0021] By selecting the nano silver powder and the hybrid silver particles as the compounded silver powder and controlling the mass ratio of the two, the present application can avoid the insufficient conductivity of the silver paste caused by too little nano silver powder, and can avoid the performance decline of the capacitor caused by too little hybrid silver particles.

[0022] As a preferred technical scheme of the present application, the preparation method of the hybrid silver particles is as follows: an intermediate product is prepared by using 4-aminobenzonitrile, p-phenylenedimethylene and DOPO as raw materials, and the intermediate product and silver nitrate are hybridized to obtain the hybrid silver particles.

[0023] As a preferred technical scheme of the present application, the preparation step of the intermediate product is as follows: 15-25 parts of trifluoromethanesulfonic acid and 7-9 parts of 4-aminobenzonitrile are mixed and stirred for 30-40 min under ice bath condition, and then the temperature is increased to 20-30℃ for stirring reaction for 12-14 h, and after adjusting the pH to neutral, centrifugation is performed to obtain yellow precipitate; 2-4 parts of the yellow precipitate and 3-5 parts of DOPO are added into 200-300 parts of anhydrous ethanol, and then 1-3 parts of p-phenylenedimethylene is added for stirring for 24-30 h, centrifugation, anhydrous ethanol washing of the precipitate, and vacuum drying, to obtain the intermediate product.

[0024] As a preferred technical scheme of the present application, the hybridization step is as follows: 2-4 parts of the intermediate product and 0.1-0.3 parts of polyvinylpyrrolidone are added into 500-600 parts of anhydrous ethanol for ultrasonic dispersion for 2-4 h, and then 24-30 parts of silver nitrate solution with a molar concentration of 0.02 mol / L is added for stirring for 4-6 h in dark, and then 0.2-0.4 parts of sodium borohydride is added for stirring for 2-4 h, centrifugation, anhydrous ethanol washing of the precipitate, and vacuum drying, to obtain the hybrid silver particles.

[0025] As a preferred technical scheme of the present application, the solvent is selected from one or more of cyclohexanone, n-butyl ether and ethylene glycol ethyl ether.

[0026] The application takes 4-aminobenzonitrile, p-phenylenedimethylene and DOPO as monomer raw materials, forms polymer microspheres as an intermediate product through reaction, then takes the intermediate product polymer microspheres as a carrier, takes silver nitrate as a metal source, utilizes the adsorption coordination and hydrogen bond effect of the Schiff base on the surface of the microspheres, and reduces and synthesizes silver nanoparticles on the surface of the microspheres, so that hybrid silver particles are prepared.

[0027] As a preferred technical scheme of the application, the drying condition in step S2 is that the temperature is 180-220 DEG C and the time is 3-5 min.

[0028] As a preferred technical scheme of the application, the calcining condition in step S2 is that the calcining is carried out at a temperature of 400-600 DEG C for 20-30 min.

[0029] As a preferred technical scheme of the application, the sintering condition in step S3 is that the temperature is 520-540 DEG C and the time is 60-70 min.

[0030] The second aspect of the application provides a high-reliability mica capacitor with a complete monolithic structure of the end, which is prepared by the preparation method of the first aspect.

[0031] Compared with the prior art, the application has the following beneficial effects:

[0032] (1) The surface modified mica sheet of the application has an excellent layered silicate structure, and the mica is stable at high temperature. Boron nitride forms a continuous or semi-continuous heat conduction path in the composite system, which avoids local heat accumulation and ensures good thermal stability of the capacitor. When the material is exposed to flame, two-dimensional nano mica and boron nitride will migrate to the surface. Two-dimensional nano mica provides a structural framework, boron nitride fills micropores and improves the thermal stability of the carbon layer, and the two form a dense, continuous and strong ceramic protective layer, which improves the flame retardant performance.

[0033] (2) The hybrid silver particles in the silver paste of the application have a triazine ring structure and DOPO. The rigid planar structure of the triazine ring and the strong intermolecular force make it stable at high temperature. The high thermal conductivity of the silver particles helps to evenly dissipate heat and avoid local overheating, improving the high temperature resistance of the material. DOPO decomposes to generate phosphorus-oxygen free radicals when heated, which capture active free radicals in the combustion chain reaction. The triazine ring decomposes to release nitrogen, which dilutes oxygen and combustible gases, and cooperates with DOPO to promote the formation of a dense carbon layer, which insulates heat and oxygen, significantly improving the flame retardant performance of the material. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments. Obviously, the drawings in the following description only some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0035] Figure 1 The XRD diagram of mica powder and two-dimensional nanometer mica in the embodiment 1 of the present application.

[0036] Figure 2 The FTIR diagram of boron nitride and amino boron nitride in the embodiment 1 of the present application. DETAILED DESCRIPTION

[0037] In order to facilitate the understanding of the present application, the present application lists the following embodiments. Those skilled in the art should understand that the embodiments are only to help understand the present application, and should not be regarded as a specific limitation on the present application.

[0038] Embodiment 1

[0039] The present embodiment provides a preparation method of a high-reliability mica capacitor with a complete monolithic structure, comprising the following steps:

[0040] S1, 20 parts of mica powder are kept at 800℃ for 60 min, then transferred into 600 parts of 5mol / L nitric acid solution, stirred at 95℃ for 5h, washed with water to neutral, dried, to obtain acid-treated mica powder; 20 parts of the acid-treated mica powder are added into 600 parts of 1mol / L sodium chloride solution, stirred at 90℃ for 4h, washed with water, dried, to obtain pretreated mica powder; 50 parts of cetyltrimethylammonium bromide is dissolved in 1000 parts of deionized water, then 25 parts of the pretreated mica powder is added, heated to 90℃ and stirred for 20h, centrifuged, the solid is washed with water and dried, then dispersed in 500 parts of anhydrous ethanol, ultrasonically broken for 40min, centrifuged to obtain supernatant containing two-dimensional nanometer mica, vacuum dried, to obtain two-dimensional nanometer mica; 6 parts of two-dimensional nanometer mica is dispersed in 600 parts of deionized water, then 0.6 parts of amino boron nitride and 0.5 parts of sodium chloride are added, stirred at 70℃ for 1h, vacuum dried, to obtain a mixture; the mixture is pressed, dried at 85℃, cut into surface modified mica sheets with an area of 1×1m 2 , and a thickness of 500μm;

[0041] S2, printing silver electrode layer on both sides of the surface modified mica sheet by screen printing, then placing on a heating plate for drying (temperature is 220℃, time is 3min), and then transferring to a tunnel sintering furnace for calcination, and obtaining mica silver sheet by calcining at a temperature of 600℃ for 20min;

[0042] S3, laminating and assembling the mica silver sheet, and then placing in a high-temperature box furnace for sintering (temperature is 540℃, time is 60min), and obtaining sintered core group;

[0043] S4, coating silver on the end of the sintered core group by using silver paste, and obtaining high-reliability mica capacitor with complete monolithic structure at the end after air drying.

[0044] Preparation of the aminated boron nitride: 8 parts of boron nitride, 200 parts of urea and 20 parts of deionized water are mixed and ground at a speed of 30r / min for 16h, then transferred to 500 parts of deionized water for stirring for 30min, and then filtered, and the filter residue is dried to obtain aminated boron nitride.

[0045] Preparation of the silver paste: 90 parts of silver powder (60 parts of nano-silver powder and 30 parts of hybrid silver particles) and 8 parts of glass powder are added to 30 parts of solvent cyclohexanone and mixed and then dispersed at high speed, and then transferred to a three-roll grinding machine for grinding to obtain silver paste.

[0046] Preparation of the hybrid silver particles: 25 parts of trifluoromethanesulfonic acid and 9 parts of 4-aminobenzonitrile are mixed and stirred for 40min under ice bath condition, and then the temperature is increased to 30℃ for stirring for 12h, and then the pH is adjusted to neutral, and then centrifuged to obtain yellow precipitate; 4 parts of the yellow precipitate and 5 parts of DOPO are added to 300 parts of anhydrous ethanol, and then 3 parts of p-phenylenedimethylene is added and stirred for 30h, and then centrifuged, and the precipitate is washed with anhydrous ethanol and vacuum dried to obtain intermediate product; 4 parts of the intermediate product and 0.3 parts of polyvinylpyrrolidone are added to 600 parts of anhydrous ethanol and ultrasonically dispersed for 4h, and then 30 parts of silver nitrate solution with a molar concentration of 0.02mol / L is added and stirred for 4h in dark, and then 0.4 parts of sodium borohydride is added and stirred for 4h, and then centrifuged, and the precipitate is washed with anhydrous ethanol and vacuum dried to obtain hybrid silver particles.

[0047] Example 2

[0048] The embodiment provides a preparation method of high-reliability mica capacitor with complete monolithic structure at the end, comprising the following steps:

[0049] S1, 10 parts of mica powder was kept at 750℃ for 60 min, then transferred into 400 parts of 5 mol / L nitric acid solution, stirred at 85℃ for 7 h, washed with water until neutral, dried to obtain acid-treated mica powder; 10 parts of the acid-treated mica powder was added into 400 parts of 1 mol / L sodium chloride solution, stirred at 80℃ for 6 h, washed with water, dried to obtain pretreated mica powder; 40 parts of cetyltrimethylammonium bromide was dissolved in 900 parts of deionized water, then 15 parts of the pretreated mica powder was added, heated to 80℃ and stirred for 24 h, centrifuged, washed with water, dried, then dispersed in 400 parts of anhydrous ethanol, ultrasonically broken for 30 min, centrifuged to obtain supernatant containing two-dimensional nanometer mica, vacuum dried to obtain two-dimensional nanometer mica; 4 parts of two-dimensional nanometer mica was dispersed in 400 parts of deionized water, then 0.4 parts of aminated boron nitride and 0.3 parts of sodium chloride were added, stirred at 60℃ for 2 h, vacuum dried to obtain a mixture; the mixture was pressed, dried at 85℃, cut into surface-modified mica sheets with an area of 1*1 m 2 , and a thickness of 500 μm;

[0050] S2, silver electrode layers were printed on both sides of the surface-modified mica sheets by screen printing, then placed on a heating flat plate for drying (temperature was 180℃, time was 5 min), then transferred into a tunnel sintering furnace for calcination, calcined at 400℃ for 30 min to obtain mica silver sheets;

[0051] S3, the mica silver sheets were assembled in layers, then placed into a high-temperature box furnace for sintering (temperature was 520℃, time was 70 min) to obtain a sintered core group;

[0052] S4, the sintered core group was coated with silver at the end using silver paste, dried to obtain a high-reliability mica capacitor with a complete monolithic structure at the end.

[0053] Preparation of the aminated boron nitride: 6 parts of boron nitride, 180 parts of urea and 10 parts of deionized water were mixed, then ground at a speed of 20 r / min for 12 h, then transferred into 400 parts of deionized water and stirred for 20 min, filtered, and the filter residue was dried to obtain aminated boron nitride.

[0054] Preparation of the silver paste: 80 parts of silver powder (60 parts of nano-silver powder and 20 parts of hybrid silver particles) and 4 parts of glass powder were added into 20 parts of solvent n-butyl ether, mixed and high-speed dispersed, then transferred into a three-roll grinder for grinding to obtain a silver paste.

[0055] Preparation of hybrid silver particles: 15 parts of trifluoromethanesulfonic acid and 7 parts of 4-aminobenzonitrile were mixed and stirred under ice bath conditions for 30 min, then warmed to 20℃ and stirred for 14 h. After adjusting the pH to neutral, centrifugation was performed to obtain a yellow precipitate; 2 parts of the yellow precipitate and 3 parts of DOPO were added to 200 parts of anhydrous ethanol, then 1 part of p-xylylene glycol was added and stirred for 24 h. Centrifugation was performed, the precipitate was washed with anhydrous ethanol, and vacuum drying was performed to obtain an intermediate product; 2 parts of the intermediate product and 0.1 parts of polyvinylpyrrolidone were added to 500 parts of anhydrous ethanol and ultrasonic dispersion was performed for 2 h. Then 24 parts of a silver nitrate solution with a molar concentration of 0.02 mol / L was added, and stirring was performed in the dark for 4 h. Then 0.2 parts of sodium borohydride was added and stirring was performed for 2 h. Centrifugation was performed, the precipitate was washed with anhydrous ethanol, and vacuum drying was performed to obtain hybrid silver particles.

[0056] Example 3

[0057] The embodiment provides a preparation method of a high-reliability mica capacitor with a complete monolithic structure, and the method comprises the following steps:

[0058] S1, 15 parts of mica powder were kept at 780℃ for 70 min, then transferred into 500 parts of 5 mol / L nitric acid solution, stirred at 90℃ for 6 h, washed with water to neutral, and dried to obtain acid-treated mica powder; 15 parts of the acid-treated mica powder were added into 500 parts of 1 mol / L sodium chloride solution, stirred at 85℃ for 5 h, washed with water, and dried to obtain pretreated mica powder; 45 parts of cetyltrimethylammonium bromide was dissolved in 950 parts of deionized water, then 20 parts of the pretreated mica powder was added, warmed to 85℃ and stirred for 22 h, centrifuged, washed with water, dried, then dispersed in 450 parts of anhydrous ethanol, ultrasonic broken for 35 min, centrifuged to obtain supernatant containing two-dimensional nanometer mica, and vacuum dried to obtain two-dimensional nanometer mica; 5 parts of the two-dimensional nanometer mica was dispersed in 500 parts of deionized water, then 0.5 parts of aminoboron nitride and 0.4 parts of sodium chloride were added, stirred at 65℃ for 1.5 h, and vacuum dried to obtain a mixture; the mixture was pressed, dried at 85℃, and cut into surface-modified mica sheets with an area of 1*1 m 2 , and a thickness of 500μm;

[0059] S2, silver electrode layers were printed on both sides of the surface-modified mica sheets by screen printing, then placed on a heating flat plate for drying (temperature: 200℃, time: 4 min), and then transferred into a tunnel sintering furnace for calcination, and calcined at 500℃ for 25 min to obtain mica silver sheets;

[0060] S3, the mica silver flake is stacked and assembled, and then is placed into a high-temperature box furnace for sintering (temperature is 530℃, time is 65min), to obtain a sintered core group;

[0061] S4, the sintered core group is coated with silver at the end using silver paste, and is dried, to obtain a high-reliability mica capacitor with a complete monolithic structure at the end.

[0062] The preparation of the aminated boron nitride: 7 parts of boron nitride, 190 parts of urea and 15 parts of deionized water are mixed and ground at a speed of 25r / min for 14h, and then are transferred into 450 parts of deionized water for stirring for 25min, and are extracted and filtered, and the filter residue is dried, to obtain aminated boron nitride.

[0063] The preparation of the silver paste: 85 parts of silver powder (60 parts of nano silver powder and 25 parts of hybrid silver particles) and 6 parts of glass powder are added into 25 parts of solvent ethylene glycol ether for mixing and high-speed dispersion, and are transferred into a three-roll grinding machine for grinding, to obtain a silver paste.

[0064] The preparation of the hybrid silver particles: 20 parts of trifluoromethane sulfonic acid and 8 parts of 4-aminobenzonitrile are mixed and stirred for 35min under ice bath conditions, and then are warmed to 25℃ for stirring for 13h, and after adjusting the pH to neutral, are centrifuged to obtain yellow precipitate; 3 parts of the yellow precipitate and 4 parts of DOPO are added into 250 parts of anhydrous ethanol, and then 2 parts of p-xylylene glycol is added for stirring for 27h, and is centrifuged, and the precipitate is washed with anhydrous ethanol and vacuum dried, to obtain an intermediate product; 3 parts of the intermediate product and 0.2 parts of polyvinylpyrrolidone are added into 550 parts of anhydrous ethanol for ultrasonic dispersion for 3h, and then 26 parts of a silver nitrate solution with a molar concentration of 0.02mol / L is added for stirring for 5h in the dark, and then 0.3 parts of sodium borohydride is added for stirring for 3h, and is centrifuged, and the precipitate is washed with anhydrous ethanol and vacuum dried, to obtain hybrid silver particles.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 1 is that commercially available mica powder is used instead of the mixed material to prepare mica flakes.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 1 is that the silver powder is all nano silver powder.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 1 is that the silver powder is all hybrid silver particles.

[0071] The performance of the capacitors provided by the above examples and comparative examples is tested,

[0072] Thermal stability of the capacitor: the capacitor is placed in a temperature chamber, the temperature chamber is heated to 130℃ at a rate of 5℃ / min and kept for 30min, the retention rate of the tested capacitor is measured; the flame retardancy test: the relevant requirements in the standard of GB / T 6346.1-2024 Fixed Capacitors for Electronic Equipment are referred to.

[0073] The performance test data are shown in Table 1.

[0074]

[0075] From the above, the two-dimensional nanometer mica is prepared by using liquid phase assisted ultrasonic exfoliation method to perform multi-step treatment on mica powder, and the surface of the two-dimensional nanometer mica is modified by amino boron nitride to process surface modified mica sheets, and based on the surface modified mica sheets, a high-reliability mica capacitor with a complete monolithic structure at the end is obtained through multiple processes (Examples 1-3), and the comprehensive performance is best.

[0076] Compared with Example 1, the commercially available mica powder is used to replace the mixture to prepare the mica sheet, and the effect of amino boron nitride is lacking, so that the thermal stability of the capacitor is poor, and the flame retardancy is reduced (Comparative Example 1); compared with Example 1, the silver powder material is all nano silver powder, and the effect of hybrid silver particles is lacking, so that the thermal stability of the capacitor is poor, and the flame retardancy is reduced (Comparative Example 2); compared with Example 1, the silver powder material is all hybrid silver particles, and the effect of nano silver powder is lacking, so that the conductivity of the silver paste is insufficient, resulting in unqualified conduction of the capacitor (Comparative Example 3).

Claims

1.A method for preparing a high-reliability mica capacitor with a complete monolithic structure, characterized in that, comprising the following steps: S1, pretreating mica powder to obtain pretreated mica powder, intercalating the pretreated mica powder to obtain two-dimensional nanometer mica, and surface-modifying the two-dimensional nanometer mica with aminated boron nitride to obtain a mixture, and then pressing, drying and cutting the mixture to obtain surface-modified mica sheets; S2, printing silver electrode layers on both sides of the surface-modified mica sheets by screen printing, and then placing the mica sheets on a heating plate to dry, and then transferring the mica sheets to a tunnel sintering furnace to calcine, to obtain mica silver sheets; S3, stacking and assembling the mica silver sheets, and then placing the mica silver sheets in a high-temperature box furnace to sinter, to obtain a sintered core group; S4, coating the sintered core group with silver at the ends using silver paste, and then drying to obtain a high-reliability mica capacitor with a complete monolithic structure; the preparation steps of the aminated boron nitride are: mixing 6-8 parts of boron nitride, 180-200 parts of urea and 10-20 parts of deionized water, and then grinding at a speed of 20-30 r / min for 12-16 h, and then transferring to 400-500 parts of deionized water and stirring for 20-30 min, and then filtering, and then drying the filter residue to obtain the aminated boron nitride; the preparation method of the silver paste is: mixing 80-90 parts of silver powder and 4-8 parts of glass powder into 20-30 parts of solvent, and then high-speed dispersing, and then transferring to a three-roll grinding machine to grind, to obtain the silver paste; the silver powder is nano silver powder and hybrid silver particles; the mass ratio of the nano silver powder to the hybrid silver particles is (2-3) : 1; the preparation method of the hybrid silver particles is: using 4-aminobenzonitrile, p-phenylenedimethylene and DOPO as raw materials to prepare an intermediate product, and then hybridizing the intermediate product with silver nitrate to obtain the hybrid silver particles; the preparation steps of the intermediate product are: mixing 15-25 parts of trifluoromethanesulfonic acid and 7-9 parts of 4-aminobenzonitrile under ice bath conditions, and then stirring for 30-40 min, and then increasing the temperature to 20-30℃ and stirring for 12-14 h, and then adjusting the pH to neutral, and then centrifuging to obtain yellow precipitate; adding 2-4 parts of the yellow precipitate and 3-5 parts of DOPO into 200-300 parts of anhydrous ethanol, and then adding 1-3 parts of p-phenylenedimethylene and stirring for 24-30 h, and then centrifuging, and then washing the precipitate with anhydrous ethanol, and then vacuum drying to obtain the intermediate product; the hybridization steps are: adding 2-4 parts of the intermediate product and 0.1-0.3 parts of polyvinylpyrrolidone into 500-600 parts of anhydrous ethanol and ultrasonic dispersing for 2-4 h, and then adding 24-30 parts of a silver nitrate solution with a molar concentration of 0.02 mol / L and stirring for 4-6 h in the dark, and then adding 0.2-0.4 parts of sodium borohydride and stirring for 2-4 h, and then centrifuging, and then washing the precipitate with anhydrous ethanol, and then vacuum drying to obtain the hybrid silver particles. 2.The method for preparing a high-reliability mica capacitor with a complete monolithic structure according to claim 1, characterized in that, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The pre-treatment step is: 10-20 parts of mica powder is kept at 750-800℃ for 60-80 min, then transferred into 400-600 parts of 5 mol / L nitric acid solution, stirred at 85-95℃ for 5-7 h, washed with water until neutral, dried to obtain acid-treated mica powder; 10-20 parts of the acid-treated mica powder is added into 400-600 parts of 1 mol / L sodium chloride solution, stirred at 80-90℃ for 4-6 h, washed with water, dried to obtain pre-treated mica powder. 3.The preparation method of the high-reliability mica capacitor with the end in the complete monolithic structure according to claim 1, characterized in that, The intercalation treatment step is: 40-50 parts of cetyltrimethylammonium bromide is dissolved in 900-1000 parts of deionized water, then 15-25 parts of the pre-treated mica powder is added, heated to 80-90℃ and stirred for 20-24 h, centrifuged, washed with water, dried, then dispersed in 400-500 parts of anhydrous ethanol, ultrasonically broken for 30-40 min, centrifuged to obtain supernatant containing two-dimensional nanometer mica, vacuum dried to obtain two-dimensional nanometer mica. 4.The preparation method of the high-reliability mica capacitor with the end in the complete monolithic structure according to claim 1, characterized in that, The surface modification step is: 4-6 parts of two-dimensional nanometer mica is dispersed in 400-600 parts of deionized water, then 0.4-0.6 parts of aminoboron nitride and 0.3-0.5 parts of sodium chloride are added, stirred at 60-70℃ for 1-2 h, vacuum dried to obtain a mixture. 5.A high-reliability mica capacitor with the end in the complete monolithic structure, characterized in that, Prepared according to the preparation method of any one of claims 1-4.

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