Ceramic dielectric material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of ceramic materials, and particularly relates to a ceramic dielectric material and a preparation method and application thereof. The ceramic dielectric material provided by the invention is prepared from the following raw materials: barium titanate, calcium zirconate, a sintering aid and a modifier, the sintering aid is a Li-Zn-B-Si glass material; and the modifier comprises one or more of Nb2O5, MnCO3, MgO and RE2O3 (rare earth oxide). The ceramic dielectric material has the advantages of high-temperature stability, high dielectric constant, low loss and high insulating property.

Description

Technical Field

[0001] This invention belongs to the field of ceramic materials technology, specifically relating to a ceramic dielectric material, its preparation method, and its application. Background Technology

[0002] Ceramic capacitors are widely used in electronic circuits across various fields, including aerospace, medical electronics, consumer electronics, communications and radio frequency (RF), automotive electronics, and industrial and energy sectors, due to their advantages such as small size, good high-frequency characteristics, high temperature stability, and low cost. As electronic devices evolve towards higher frequencies, higher voltages, higher reliability, and smaller sizes, the technology of ceramic capacitors is also constantly evolving, thereby continuously driving the technological iteration and upgrading of capacitor dielectric materials.

[0003] The capacitance temperature coefficient (TCC) represents the rate at which capacitance changes with temperature. It is one of the key parameters of ceramic capacitors and the ceramic dielectric material used. Properly selecting the capacitance temperature coefficient can significantly improve the stability and reliability of the circuit. For capacitor products, different products can be selected for different application scenarios:

[0004] (1) High stability applications (such as C0G) have a TCC close to zero (0±30ppm / ℃). The capacitance remains almost unchanged with temperature changes and the frequency stability is good. They are mainly used in high-frequency communication, precision instruments, aerospace and other fields with high temperature sensitivity. The dielectric constant is usually ≤80. For high stability applications, the high capacitance temperature stability and high frequency temperature stability of a certain type of ceramic material are mainly used. This usually limits the dielectric constant of the selected material, which limits the capacitance range of the capacitor and restricts the miniaturization of the device.

[0005] (2) General applications (such as X7R) have a wider TCC (X7R has a tolerance of ±15%), allowing for certain fluctuations. They are mainly used in cost-sensitive scenarios such as power decoupling and consumer electronics. Typically, the dielectric constant is ≥1500. For general applications, the high dielectric constant of the second type of ceramic material is mainly used to achieve the large capacity of the capacitor. The capacitor is mainly used at low frequencies and cannot meet the requirements of high capacity temperature stability and high capacity frequency stability.

[0006] (3) High-capacity variable applications (such as Y5V) have a relatively large TCC (+22% to -82% tolerance), and the capacity decreases significantly with increasing temperature. They are mainly used in applications where temperature drift is not strictly required, such as low-frequency filtering or energy storage. Typically, the dielectric constant is ≥8000. For high-capacity variable applications, the ultra-high dielectric constant of type II ceramic materials is mainly utilized, while TCC and frequency characteristics are secondary considerations.

[0007] However, with the miniaturization of capacitor devices, the dielectric constant of the ceramic dielectric material used is required to be higher (so that the capacitance of the capacitor is larger). But generally speaking, as the dielectric constant of the ceramic dielectric material increases, the capacitance fluctuates more with temperature, that is, the capacitance temperature coefficient (TCC) is wider. This means that the miniaturization of the device has an almost unavoidable impact on the stability of the circuit.

[0008] In related technologies, ceramic dielectric materials for capacitors with dielectric constants of 110 to 400, especially those with higher dielectric constants of 300 to 400, are typically strontium-calcium-bismuth-titanium and barium-calcium-zirconium-titanium systems. Both have adjustable dielectric constants and temperature coefficients, but their capacitance temperature coefficients are very wide and severely negative (TCC ≤ -1000ppm / ℃ in the range of -55 to 125℃). This TCC limits the application of capacitors in fields where stability and reliability in circuits are critical.

[0009] According to GB / T 5596-1996 Ceramic Dielectric Materials for Capacitors, for ceramic materials with a dielectric constant of 300-400, the TCC (Total Dielectric Capacitance) typically meets Group D (-3300±500ppm / ℃) within the temperature range of -55 to 125℃. However, in actual literature reviews, the TCC is usually (-3000 to -2000) ppm / ℃ or lower, while the TCC of imported ceramic materials of the same type is -2200±250ppm / ℃. In summary, the relevant technology has the following drawbacks:

[0010] 1) Existing ceramic dielectric materials often have poor temperature stability while meeting the requirements of high dielectric constant. Their dielectric properties vary greatly over a wide temperature range. When selecting them, both dielectric constant and TCC must be considered. It is impossible to simultaneously meet the requirements of high dielectric constant and high temperature stability.

[0011] 2) The room temperature and high temperature insulation resistivity of existing ceramic dielectric materials are not high enough; typically, the insulation resistivity at 125℃ is ≤10. 12 Ω·cm. Summary of the Invention

[0012] In view of this, the purpose of this invention is to provide a ceramic dielectric material, its preparation method and application. The ceramic dielectric material provided by this invention has high temperature stability, high dielectric constant, low loss and high insulation performance.

[0013] To achieve the above objectives, the present invention provides the following technical solution:

[0014] This invention provides a ceramic dielectric material, the raw materials for which include barium titanate, calcium zirconate, sintering aids and modifiers;

[0015] The sintering aid is Li-Zn-B-Si glass frit;

[0016] The modifier includes one or more of Nb2O5, MnCO3, MgO and RE2O3.

[0017] Preferably, RE in the RE2O3 is one or more of Y, La, Nd and Sm.

[0018] Preferably, the mass ratio of barium titanate to calcium zirconate is 100:19-26; the mass ratio of barium titanate to sintering aid is 100:2.5-3.3; and the mass ratio of barium titanate to modifier is 100:6.1-8.6.

[0019] Preferably, the mass ratio of barium titanate to Nb2O5 is 100:5.5-8; the mass ratio of barium titanate to MnCO3 is 100:0.1-0.3; the mass ratio of barium titanate to MgO is 100:0.1-0.2; and the mass ratio of barium titanate to RE2O3 is 100:0-0.25.

[0020] The present invention also provides a method for preparing the ceramic dielectric material described in the above technical solution, comprising the following steps:

[0021] Barium titanate, calcium zirconate, sintering aids and modifiers are mixed and sintered to obtain the ceramic dielectric material.

[0022] Preferably, the sintering temperature is 1120–1170°C, and the holding time is 2–3 hours.

[0023] Preferably, the mixing is ball milling; the ball milling is wet ball milling; the reagent used in the wet ball milling is water; the ratio of the total mass of barium titanate, calcium zirconate, sintering aid and modifier to the mass of the reagent used in the wet ball milling is 20:70-90; the ball milling time is 4-8 hours; and the ball milling speed is 300-380 rpm.

[0024] Preferably, the mixing process further includes: granulating and molding the mixture obtained by mixing barium titanate, calcium zirconate, sintering aid, and modifier in sequence; removing the binder from the resulting green body and then sintering it; the granulation involves mixing the mixture obtained by mixing barium titanate, calcium zirconate, sintering aid, and modifier with a binder and then grinding it to allow the solvent to evaporate, thereby obtaining granules; the binder is polyvinyl butyral and / or polyvinyl alcohol.

[0025] The present invention also provides the application of the ceramic dielectric material described in the above technical solution or the ceramic dielectric material prepared by the preparation method described in the above technical solution in capacitors.

[0026] The present invention also provides a capacitor, comprising a ceramic substrate and electrodes coated on the ceramic substrate; the material of the ceramic substrate is the ceramic dielectric material described in the above technical solution or the ceramic dielectric material prepared by the preparation method described in the above technical solution.

[0027] This invention provides a ceramic dielectric material, the raw materials of which include barium titanate, calcium zirconate, sintering aids, and modifiers; the sintering aid is Li-Zn-B-Si glass frit; the modifier includes one or more of Nb₂O₅, MnCO₃, MgO, and RE₂O₃. In this invention, the Ca in calcium zirconate... 2+ Replacement of barium titanate Ba 2+ Position, due to Ca 2+ The small ionic radius of Zr causes lattice contraction; 4+ Replace Ti 4+ Site, Zr 4+ The large ionic radius leads to local expansion; CaZrO3 reacts with BaTiO3 to form Ba 1- x Ca x Zr y Ti 1-y O3 solid solution, through stress coupling, broadens the phase transition temperature range and induces random distribution of polar nanoregions. The phase transition temperature in different regions is dispersed due to local stress differences, resulting in overall broadened dielectric peaks and exhibiting characteristics similar to "relaxed ferroelectric" materials. The addition of Nb2O5 further disrupts long-range ferroelectric order, broadens the phase transition temperature range, enhances relaxor ferroelectric properties, and further reduces the temperature sensitivity of the dielectric constant. MnCO3 can reduce dielectric loss, and low-cost Mn... 2+ Replace Ti 4+ The A-site and B-site of the MgO-B-site in perovskite ceramics form defect dipoles, pinning ferroelectric domain wall motion, suppressing dielectric relaxation loss, and reducing remanent polarization. MgO can effectively regulate the A-site and B-site in perovskite ceramics, reducing oxygen vacancies and preventing their movement, maintaining high reliability, and improving temperature characteristics. The introduction of rare earth elements enhances temperature stability and improves material reliability through synergistic optimization of crystal structure, microstructure, and polarization behavior. Li-Zn-B-Si glass frit, as a sintering aid, can form a liquid phase layer at grain boundaries, lowering the sintering temperature and promoting dense sintering. Therefore, the ceramic dielectric material provided by this invention possesses high-temperature stability, high dielectric constant, low loss, and high insulation performance.

[0028] The test results of the examples show that the dielectric constant of the disc capacitor prepared using the ceramic dielectric material of the present invention is 230-350, the loss is no higher than 0.0042, and the capacitance temperature coefficient is controlled within (-500 to +150) ppm / ℃ in the temperature range of -55 to 125℃, with extremely narrow capacitance temperature variation; the insulation resistivity of the disc capacitor can reach 10 at both room temperature and high temperature of 125℃.13 The capacitance is at the Ω·cm level, meeting the high reliability requirements of capacitors. The single-layer ceramic capacitor prepared using the ceramic dielectric material of this invention has a capacitance-to-dielectric constant of 370, a loss of 0.0038, an insulation resistance in the TΩ level, and a capacitance-temperature variation range (TCC) of (-248 to -43) ppm / ℃. It exhibits excellent temperature stability and high reliability.

[0029] The present invention also provides a method for preparing the ceramic dielectric material. The raw materials used in the present invention are conventional industrial raw materials, which do not contain toxic or harmful substances and are environmentally friendly materials. The preparation process adopts ball milling technology, which is simple and easy to realize industrial production. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the manufacturing process of a single-layer ceramic capacitor in an application example of the present invention.

[0031] Figure 2 The image shows a cross-sectional SEM image of the monolayer ceramic capacitor prepared in Example 13. Detailed Implementation

[0032] This invention provides a ceramic dielectric material, the raw materials for which include barium titanate, calcium zirconate, sintering aids and modifiers;

[0033] The sintering aid is Li-Zn-B-Si glass frit;

[0034] The modifier includes one or more of Nb2O5, MnCO3, MgO and RE2O3.

[0035] Unless otherwise specified, the present invention does not have special requirements on the source of raw materials used, and commercially available products well known to those skilled in the art can be used.

[0036] In one embodiment, the barium titanate (BaTiO3) is a commercially available product; the barium titanate has a grain size of 200–350 nm and a particle size D. 50 ≤0.7μm, D 90 ≤1.0μm; Barium titanate has good crystallinity.

[0037] As one embodiment, the calcium zirconate (CaZrO3) has a particle size of D50 ≤ 1.0 μm and D90 ≤ 5.0 μm; the calcium zirconate is synthesized by a solid-phase method; the solid-phase synthesis preparation process of the calcium zirconate is as follows: CaCO3 and ZrO2 are mixed and wet-milled, and the resulting slurry is successively dried, sieved, and sintered to obtain calcium zirconate; the molar ratio of CaCO3 to ZrO2 is 1 to 1.05:1, and in a specific embodiment it is 1:1; the reagent used for wet-milling is water; the wet-milling time is... The drying time is 4-8 hours, specifically 5 hours in this embodiment; the wet ball milling speed is 300-380 rpm, specifically 350 rpm in this embodiment; the drying temperature is 120-130℃, specifically 125℃ in this embodiment, and the drying time is 6-12 hours, specifically 10 hours in this embodiment; the sieve mesh size used for sieving is 40-80 mesh, specifically 40 mesh in this embodiment; the sintering temperature is 1200±50℃, specifically 1230℃ in this embodiment, and the holding time is 2-3 hours, specifically 3 hours in this embodiment.

[0038] In calcium zirconate, Ca 2+ Replacement of barium titanate Ba 2+ Position, due to Ca 2+ The small ionic radius of Zr causes lattice contraction; 4+ Replace Ti 4+ Site, Zr 4+ The large ionic radius leads to local expansion; CaZrO3 reacts with BaTiO3 to form Ba 1-x Ca x Zr y Ti 1-y O3 solid solution, through stress coupling, broadens the phase transition temperature range and induces random distribution of polar nanoregions. The phase transition temperature of different regions is dispersed due to local stress differences, and the overall dielectric peak is broadened, exhibiting a similar appearance to "relaxed ferroelectric" materials.

[0039] In one embodiment, the Li-Zn-B-Si glass frit was purchased from Foshan Jinggu Materials Technology Co., Ltd., model number FJB1722. As a sintering aid, the Li-Zn-B-Si glass frit can form a liquid phase layer at the grain boundaries, lowering the sintering temperature and promoting dense sintering.

[0040] In one embodiment, the modifier includes one or more of Nb₂O₅, MnCO₃, MgO, and RE₂O₃, specifically Nb₂O₅, MnCO₃, and MgO, or Nb₂O₅, MnCO₃, MgO, and Nd₂O₃, or Y₂O₃, La₂O₃, or Sm₂O₃; wherein RE₂O₃ is one or more of Y, La, Nd, and Sm, specifically Y, La, Nd, or Sm. The modifier used in this invention is a commercially available product.

[0041] In this invention, the modifier functions to: further reduce the temperature sensitivity of the dielectric constant; reduce dielectric loss; enhance insulation performance; regulate microstructure, and enhance reliability. The addition of Nb₂O₅ further disrupts long-range ferroelectric order, broadens the phase transition temperature range, enhances relaxation ferroelectric properties, and further reduces the temperature sensitivity of the dielectric constant. MnCO₃ can reduce dielectric loss, and low-cost Mn... 2+ Replace Ti 4+ The A-site and B-site of a perovskite ceramic form a defect dipole, pinning ferroelectric domain wall motion, suppressing dielectric relaxation loss, and reducing remanent polarization. MgO can effectively modulate the A-site and B-site of perovskite ceramics, reducing oxygen vacancies and preventing their movement, maintaining high reliability, and improving temperature characteristics. The introduction of rare earth elements, through synergistic optimization of crystal structure, microstructure, and polarization behavior, can enhance temperature stability and improve material reliability.

[0042] In one embodiment, the mass ratio of barium titanate to calcium zirconate is 100:19–26, specifically 100:19, 100:20, 100:21, 100:22, 100:24, or 100:26; the mass ratio of barium titanate to sintering aid is 100:2.5–3.3, specifically 100:2.75, 100:2.8, 100:2.85, 100:3, 100:3.1, or 100: 3.2 or 100:3.3; the mass ratio of barium titanate to modifier is 100:6.1 to 8.6, specifically 100:6.1, 100:6.3, 100:6.56, 100:6.71, 100:6.91, 100:7.15, 100:7.3, 100:7.5, 100:7.53, 100:7.8, or 100:8.6 in the embodiments; the mass ratio of barium titanate to Nb₂O₅ is 100:5.5. ~8, specifically 100:5.5, 100:6, 100:6.3, 100:6.4, 100:6.5, 100:7, 100:7.2, 100:7.5 or 100:8; the mass ratio of barium titanate to MnCO3 is 100:0.1 to 0.3, specifically 100:0.1, 100:0.11, 100:0.13, 100:0.15, 100:0.2 or 100:0. 3; The mass ratio of barium titanate to MgO is 100:0.1 to 0.2, and in specific embodiments it is 100:0.1, 100:0.11, 100:0.13, 100:0.15 or 100:0.2; The mass ratio of barium titanate to RE2O3 is 100:0 to 0.25, and in specific embodiments it is 100:0, 100:0.05, 100:0.1, 100:0.15, 100:0.2 or 100:0.25.

[0043] The present invention also provides a method for preparing the ceramic dielectric material described in the above technical solution, comprising the following steps:

[0044] Barium titanate, calcium zirconate, sintering aids and modifiers are mixed and sintered to obtain the ceramic dielectric material.

[0045] In one embodiment, the mixing is ball milling; the ball milling is wet ball milling; the reagent used in the wet ball milling is water, specifically deionized water in this embodiment; the ratio of the total mass of barium titanate, calcium zirconate, sintering aid, and modifier to the mass of the reagent used in the wet ball milling is 20:70-90, specifically 20:80 in this embodiment; the ball milling media used is zirconia balls; the diameter of the zirconia balls is 3-5 mm, specifically 3 mm and 5 mm in this embodiment; the ball-to-material ratio during the ball milling process is 6-10:1, specifically 8:1 in this embodiment; the ball milling time is 4-8 hours, specifically 4 hours in this embodiment; the ball milling speed is 300-380 rpm, specifically 350 rpm in this embodiment; the particle size of the powder obtained from the ball milling is D. 50 ≤1.0μm and D 90 ≤2.0μm, specifically D in the embodiment 50 ≤0.8μm and D 90 ≤1.5μm; after the wet ball milling, the process further includes: drying the slurry after wet ball milling; the drying temperature is 120~130℃, specifically 125℃ in this embodiment, and the drying time is 6~12h, specifically 8h in this embodiment. This invention uses ball milling to mix the materials evenly and grind large particles into finer particles.

[0046] In one embodiment, the mixing process further includes: granulating and molding the mixture obtained by mixing barium titanate, calcium zirconate, sintering aid, and modifier sequentially; debinding the resulting green body before sintering; the granulation involves mixing the mixture obtained by mixing barium titanate, calcium zirconate, sintering aid, and modifier with a binder, followed by grinding to evaporate the solvent and obtain granules; the binder is polyvinyl butyral (PVB) and / or polyvinyl alcohol (PVA), specifically polyvinyl butyral in this embodiment; the binder is used in the form of an alcoholic solution of the binder; The alcoholic solution of the binder contains 10±2% by mass, specifically 10% in this embodiment; the amount of the alcoholic solution of the binder added to the mixture obtained by mixing barium titanate, calcium zirconate, sintering aid, and modifier is 1±0.2 mL / g, specifically 1 mL / g in this embodiment; the grinding is carried out in a mortar; the mortar is an agate mortar; the molding is performed by pressing in a mold; the pressing pressure is 330±30 MPa, specifically 330 MPa in this embodiment, and the holding time is 30-90 s, specifically 60 s in this embodiment. This invention does not have a special limitation on the shape of the green blank obtained by pressing, and can be selected as needed. In this embodiment, the green blank obtained by pressing is a circular green blank with a diameter of 10±1 mm; the equipment used for debinding is a box furnace; the debinding temperature is 400-500℃, specifically 450℃ in this embodiment, and the holding time is 3-5 h, specifically 4 h in this embodiment; the debinding is carried out in an air atmosphere.

[0047] In this invention, the binder enhances the adhesion and plasticity between powder particles, improves powder flowability, and allows the powder to fill the mold uniformly and quickly. This invention uses a mold to press the granulated material into shape.

[0048] In one embodiment, the sintering temperature is 1120–1170°C, specifically 1150°C, and the holding time is 2–3 hours, specifically 2 hours; the heating rate to the sintering temperature is 3–4°C / min, specifically 3.5°C / min; the sintering is carried out in an air atmosphere; after sintering, the process further includes cooling the sintered product to room temperature with the furnace.

[0049] The present invention also provides the application of the ceramic dielectric material described in the above technical solution or the ceramic dielectric material prepared by the preparation method described in the above technical solution in capacitors.

[0050] The present invention also provides a capacitor, comprising a ceramic substrate and electrodes coated on the ceramic substrate; the material of the ceramic substrate is the ceramic dielectric material described in the above technical solution or the ceramic dielectric material prepared by the preparation method described in the above technical solution.

[0051] In one embodiment, the capacitor is prepared by coating both sides of a surface-treated ceramic substrate with electrode paste, followed by drying and sintering to obtain the capacitor. The surface treatment involves sanding with sandpaper to remove adhering impurities from the ceramic substrate surface and to make the surface relatively smooth. The drying temperature is 110–130°C, specifically 120°C in this embodiment, and the drying time is 10–20 min, specifically 15 min in this embodiment. The sintering temperature is 750–800°C, specifically 780°C in this embodiment, and the holding time is 0.5–1 h, specifically 0.6 h in this embodiment. The sintering is carried out in an air atmosphere.

[0052] In one embodiment, the capacitor is a single-layer ceramic capacitor; the method for preparing the single-layer ceramic capacitor includes the following steps:

[0053] The raw materials, solvents and dispersants for preparing ceramic media materials are mixed and formulated. The resulting slurry is then cast and coated onto a base tape to obtain a green ceramic tape.

[0054] After the green ceramic strips are stacked into green blocks, they are uniformly pressed and cut to obtain square green blocks;

[0055] The square green body is sintered into porcelain. After the surface of the sintered porcelain body is ground smooth, it is cleaned and dried. Then, a metal layer is sputtered and deposited on both ends of the dried sintered porcelain body.

[0056] After spin-coating photoresist onto the metal layer, an end electrode pattern mask is formed by exposure and development. Excess metal areas are removed by photolithography to pattern the metal electrode pattern.

[0057] The patterned material is sequentially diced, tested, and packaged to obtain the single-layer ceramic capacitor.

[0058] In one embodiment, the solvent is toluene and / or ethanol, specifically toluene and ethanol; the dispersant is JM508, purchased from Hubei Jiaming New Material Co., Ltd.; the mass ratio of the ceramic medium material to the solvent is 1:1; the mass ratio of the ceramic medium material to the dispersant is 100:1; the casting equipment is a casting machine; the base tape is polyethylene terephthalate (PET) base tape; the uniform pressing is an isostatic pressing treatment; the isostatic pressing pressure is 40 MPa, and the holding time is 15 min; the square... The side length of the green blank is 5cm; the sintering temperature is 1100~1150℃, specifically 1140℃ in this embodiment, and the holding time is 2h; the sintering is carried out in an air atmosphere; the metal layer is a stepwise sputtered transition layer 2, transition layer 1 and gold electrode layer, which correspond to TiW, Ni and Au respectively; the dicing is to cut the patterned material into 1.5mm×1.5mm units; the testing includes capacity, loss, insulation and temperature characteristics; the packaging is to sequentially tape, reel and seal the qualified products obtained after testing and sorting.

[0059] The ceramic dielectric material of this invention is suitable for industrial production and is compatible with the manufacturing process of single-layer ceramic capacitors. Furthermore, the capacitors exhibit excellent performance and are suitable for the design, development, and application of further miniaturized, high-temperature stable single-layer capacitors.

[0060] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0061] Examples 1-12

[0062] The formulations of barium titanate, calcium zirconate, sintering aids, and modifiers in the raw materials for preparing ceramic dielectric materials are shown in Table 1.

[0063] The preparation method of the ceramic media material is as follows: Weigh 20g of the main material, auxiliary material, modifier, and sintering aid according to the weight ratio designed in Table 1 into a 250mL ball mill jar. Use zirconia balls with diameters of 3mm and 5mm as the ball milling media, with a ball-to-material ratio of 8:1. Add 80g of deionized water and then wet-mill at 350rpm for 4 hours to mix. The resulting slurry (where the particle size of the solid powder is D) is obtained. 50 ≤0.8μm and D 90≤1.5μm) and then placed in an oven to dry at a constant temperature of 125℃ for 8h; take 2g of dried powder and add 2mL of PVB alcohol solution (PVB mass content is 10%) to grind and granulate. Place the granulated material in a mold and press it into shape at 330MPa for 60s to obtain a round green blank with a diameter of 10mm. Place the green blank in a box furnace and hold it at 450℃ for 4h to remove the glue according to the set curve. Then, heat it to 1150℃ at a heating rate of 3.5℃ / min and hold it for 2h for sintering. Then, cool it to room temperature with the furnace to obtain ceramic dielectric material, i.e. dielectric ceramic disc.

[0064] Table 1 Formulation Design Table for Examples 1-12

[0065]

[0066] Application Examples 1-12

[0067] After the dielectric ceramic discs prepared in Examples 1 to 12 were sanded, electrode paste was coated on both sides of the sanded discs. After drying at 120°C for 15 min, they were sintered at 780°C for 0.6 h in air to obtain disc capacitors.

[0068] Application Example 13

[0069] like Figure 1 As shown, the production process of a single-layer ceramic capacitor is as follows: The raw materials for preparing the ceramic dielectric material in Example 4 are mixed uniformly with solvents (toluene and ethanol, with a mass ratio of 1:1) and dispersant (JM508, with a mass ratio of 100:1) to obtain a slurry; the slurry is uniformly coated onto a PET base tape using a casting machine to obtain a green ceramic tape; the green ceramic tape is stacked into a green block; the green block is subjected to isostatic pressing at 40 MPa to achieve dense interlayer bonding, with a holding time of 15 min; the uniformly pressed green block is then cut into pieces with a side length of… A 5cm square green blank is prepared; the cut green blank is then sintered in air at 1140℃ for 2 hours to form a ceramic; the ceramic surface is ground smooth, cleaned, and dried; a metal layer (TiW / Ni / Au) is then sputtered and deposited on both ends of the ceramic body; photoresist is spin-coated onto the metal layer, and after exposure and development, an end electrode pattern mask is formed; excess metal areas are etched by photolithography to retain the metal electrode pattern; the patterned material is cut into 1.5mm×1.5mm units; various performance tests (capacity, loss, insulation, temperature characteristics) are then performed to sort out qualified products, and finally, tape, reel, and moisture-proof packaging are carried out.

[0070] Comparative Example 1

[0071] The difference from Example 4 is that the sintering aid is removed.

[0072] Comparative Example 2

[0073] The difference from Example 4 is that the modifier is removed.

[0074] Comparative Example 3

[0075] The difference from Example 4 is that Nb2O5 in the modifier is removed.

[0076] Comparative Example 4

[0077] The difference from Example 4 is that Nb2O5 and MnCO3 in the modifier are removed.

[0078] Comparative Examples 1-4 have the same raw material composition and preparation process as Examples 1-12. The difference lies in the raw material ratio, modifier and sintering aid. For specific parameters, please refer to Table 2.

[0079] Table 2 Formulation Design Table for Comparative Examples 1-4

[0080]

[0081] Comparative Application Examples 1-4

[0082] The difference from Application Example 4 is that the dielectric ceramic discs prepared in Example 4 are replaced with the dielectric ceramic discs prepared in Comparative Examples 1 to 4 to make disc capacitors.

[0083] Performance testing

[0084] (1) The disc capacitors prepared in comparative application examples 1 to 4 and application examples 1 to 12 were tested under the test condition of 1V / 1MHz. The results are shown in Tables 3 and 4.

[0085] Table 3 compares the performance of disc capacitors in Application Examples 1-4 (test conditions: 1V / 1MHz).

[0086]

[0087] Table 3 shows that, by comparing the performance of Application Example 4 with that of Comparative Application Example 1, it is evident that without the presence of sintering aids, many properties of the disc capacitor deteriorate significantly. Although the TCC increases substantially, the dielectric constant drops to 171, nearly halved, the loss increases dramatically to 0.0313, and the insulation performance deteriorates drastically. This demonstrates that suitable sintering aids play a crucial role in the sintering of dielectric materials and the excellent performance of the capacitor. By comparing the performance of Application Example 4 with Comparative Application Examples 2, 3, and 4, it is clear that even with sintering aids, without the presence of modifiers, or without Nb₂O₅ and MnCO₃ in the modifiers, although the dielectric constant increases substantially, the TCC becomes severely negative, and the insulation resistance decreases sharply. This shows that each component in the modifier plays a key role in the performance of the dielectric material and the capacitor. Only with the synergistic effect of the components in the dielectric material formulation can the capacitor exhibit excellent comprehensive performance, thus meeting the requirements of applications with high stability and reliability in circuits.

[0088] Table 4 shows the performance of disc capacitors in Application Examples 1-12 (test conditions: 1V / 1MHz).

[0089]

[0090] As shown in Table 4, the disc capacitors in the application examples listed in this invention have a dielectric constant of 230 to 350 under test conditions of 1V / 1MHz, and the TCC is controlled within the range of (-500 to +150)ppm / ℃, exhibiting excellent temperature stability; the insulation resistivity at both room temperature and high temperature is above 10¹³Ω·cm, demonstrating excellent insulation performance.

[0091] (2) The performance of the single-layer ceramic capacitor prepared in Example 13 was tested under the test conditions of 1V / 1MHz. The results are shown in Table 5.

[0092] Table 5 shows the performance of the single-layer ceramic capacitor prepared in Application Example 13 (test conditions: 1V / 1MHz).

[0093]

[0094] As shown in Table 5, the single-layer ceramic capacitor prepared using the ceramic material of Example 4 has a capacitance-to-dielectric constant of 370 and a loss of only 0.0038. The TCC is in the range of -220±30ppm / ℃, which meets the RG characteristic requirements.

[0095] (3) Figure 2 The cross-sectional SEM image of the single-layer ceramic capacitor prepared in Example 13 shows that the sintering of the ceramic body, transition layer and electrode layer is good.

[0096] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A ceramic dielectric material, characterized in that, The raw materials for preparation include barium titanate, calcium zirconate, sintering aids, and modifiers; The sintering aid is Li-Zn-B-Si glass frit; The modifier includes one or more of Nb2O5, MnCO3, MgO and RE2O3.

2. The ceramic dielectric material according to claim 1, characterized in that, In the RE2O3, RE is one or more of Y, La, Nd, and Sm.

3. The ceramic dielectric material according to claim 1, characterized in that, The mass ratio of barium titanate to calcium zirconate is 100:19-26; the mass ratio of barium titanate to sintering aid is 100:2.5-3.3; and the mass ratio of barium titanate to modifier is 100:6.1-8.

6.

4. The ceramic dielectric material according to claim 1, characterized in that, The mass ratio of barium titanate to Nb2O5 is 100:5.5-8; the mass ratio of barium titanate to MnCO3 is 100:0.1-0.3; the mass ratio of barium titanate to MgO is 100:0.1-0.2; and the mass ratio of barium titanate to RE2O3 is 100:0-0.

25.

5. The method for preparing the ceramic dielectric material according to any one of claims 1 to 4, characterized in that, Includes the following steps: Barium titanate, calcium zirconate, sintering aids and modifiers are mixed and sintered to obtain the ceramic dielectric material.

6. The preparation method according to claim 5, characterized in that, The sintering temperature is 1120–1170℃, and the holding time is 2–3 hours.

7. The preparation method according to claim 5, characterized in that, The mixing is ball milling; the ball milling is wet ball milling; the reagent used in the wet ball milling is water; the ratio of the total mass of barium titanate, calcium zirconate, sintering aid and modifier to the mass of the reagent used in the wet ball milling is 20:70-90; the ball milling time is 4-8 hours; the ball milling speed is 300-380 rpm.

8. The preparation method according to claim 5 or 7, characterized in that, The process after mixing further includes: granulating and molding the mixture obtained by mixing barium titanate, calcium zirconate, sintering aid and modifier in sequence; removing the binder from the resulting green body and then sintering it; the granulation involves mixing the mixture obtained by mixing barium titanate, calcium zirconate, sintering aid and modifier with a binder and then grinding it to allow the solvent to evaporate, thereby obtaining granules; the binder is polyvinyl butyral and / or polyvinyl alcohol.

9. The application of the ceramic dielectric material according to any one of claims 1 to 4 or the ceramic dielectric material prepared by the preparation method according to any one of claims 5 to 8 in a capacitor.

10. A capacitor, characterized in that, It includes a ceramic substrate and an electrode covering the ceramic substrate; the material of the ceramic substrate is the ceramic dielectric material according to any one of claims 1 to 4 or the ceramic dielectric material prepared by the preparation method according to any one of claims 5 to 8.

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