Base metal high-voltage multilayer ceramic dielectric capacitor and preparation method thereof

Abstract

The invention relates to a base metal high-voltage multilayer ceramic dielectric capacitor and a preparation method, the base metal high-voltage multilayer ceramic dielectric capacitor is formed by stacking and firing dielectric layers, and each dielectric layer comprises a dielectric layer and an electrode printed on the dielectric layer. The dielectric layer comprises the following raw materials: a BMYT main matrix, an NN material, magnesium oxide, manganous-manganic oxide, zirconium dioxide, calcium carbonate, strontium carbonate and rare earth oxide; through the raw material composition and the preparation method of the ceramic dielectric capacitor, the prepared ceramic dielectric capacitor has excellent performances of high dielectric constant, high voltage resistance, stable dielectric-temperature characteristic curve, low loss, high insulation resistance, long-term high-voltage reliability and the like under the condition of high dielectric thickness (30 microns before firing).

Description

Technical Field

[0001] This invention belongs to the field of ceramic capacitor manufacturing, specifically relating to a base metal high-voltage multilayer ceramic capacitor and its manufacturing method. Background Technology

[0002] Multilayer ceramic capacitors (MLCCs) are a type of surface-mount capacitor whose main functions include bypassing, decoupling, filtering, and energy storage. MLCCs are manufactured using an alternating layering and co-firing process of ceramic dielectric and metal electrodes. They are characterized by their small size, high specific capacitance, high voltage resistance, high reliability, and low cost. They are the most widely used passive components globally, extensively applied in consumer electronics, 5G communications, new energy, and automotive electronics. The barium titanate ceramic powder formulation is one of their core technologies.

[0003] Multilayer ceramic capacitors (MLCCs) are fabricated using a tape-co-firing process. This involves tape casting, printing, and lamination to stack the dielectric and electrode layers, followed by debinding, sintering, and termination to create the multilayer ceramic capacitor. To reduce costs, base metals such as nickel are typically used for the internal electrodes. Since base metals oxidize when sintered in air, base metal MLCCs require co-firing in a reducing atmosphere. Pure barium titanate is easily reduced in a reducing atmosphere, generating oxygen vacancy defects. Furthermore, it fails to meet requirements in terms of temperature stability, dielectric strength, dielectric loss, and reliability. Therefore, barium titanate needs to be doped to improve its electrical properties and reliability. In addition, the breakdown electric field strength of dielectric materials often decreases with increasing dielectric thickness. High-voltage MLCCs, due to their high rated voltage, require thicker dielectric layers. The lower breakdown field strength under high dielectric thickness is insufficient to meet the voltage withstand and reliability requirements of ultra-high-voltage capacitors. Therefore, developing material formulations that maintain high breakdown field strength under high dielectric thickness is of great significance.

[0004] The technical challenge of base metal high-voltage multilayer ceramic capacitors lies in how to simultaneously achieve high withstand voltage, high dielectric constant, high insulation resistance, excellent temperature stability, and long-term high-voltage reliability under conditions of high dielectric thickness and high electric field strength. For high-voltage MLCCs to achieve superior performance, the dielectric material formulation must first possess excellent high-voltage characteristics, and a suitable MLCC manufacturing process must be employed to ultimately achieve high withstand voltage and high reliability. Therefore, the problem this invention aims to solve is how to obtain a high-performance formulation by controlling the material composition and doping process, and how to apply it to base metal, high-voltage, and highly reliable high-voltage multilayer ceramic capacitors. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a base metal high-voltage multilayer ceramic capacitor and its preparation method.

[0006] The present invention adopts the following technical solution: A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers. The dielectric layer includes a dielectric layer and electrodes printed on the dielectric layer. The dielectric layer includes the following molar parts of raw materials: 100 parts of BMYT matrix, 0.2-1.0 parts of NN material, 0.5-1.5 parts of magnesium oxide, 0.05-0.2 parts of manganese tetroxide, 0.2-1.0 parts of zirconium dioxide, 0.2-1.0 parts of calcium carbonate, 0.2-1.0 parts of strontium carbonate, and 0.2-2.0 parts of rare earth oxides. The BMYT matrix comprises the following molar amounts of raw materials: 100 parts BT material, 0.5-1.5 parts magnesium oxide, and 0.5-3.0 parts yttrium oxide; The NN material is composed of sodium carbonate and niobium pentoxide in a molar ratio of 2:1.

[0007] Furthermore, the rare earth oxide is one or more of ytterbium oxide, erbium oxide, and holmium oxide.

[0008] Furthermore, the BT material is barium titanate powder with an average particle size of 500 nm.

[0009] A method for preparing a base metal high-voltage multilayer ceramic capacitor includes the following steps: Step 1: Synthesis of BMYT host matrix using solid-state method; Step 2: Solid-state synthesis of NN materials; Step 3, Preparation of Casting Slurry: Add ethanol, toluene, and dispersant to a sand mill, then add BMYT matrix, NN material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, strontium carbonate, and rare earth oxides according to the formula. Stir for 2-4 hours and sand mill for 2-6 hours. Then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2-4 hours and sand mill for 2-6 hours to grind the average particle size to 300 nm. Filter and defoam to obtain the casting slurry. The weight ratio of BMYT matrix: ethanol: toluene: dispersant is 100:15-35:15-35:0.5-2, and the ratio of BMYT matrix: dioctyl phthalate: polyvinyl butyral resin is 100:1-5:6-10. Step 4, Green Fabrication: The slurry is cast into a dielectric layer with a thickness of 10μm. Then, nickel electrode slurry is printed onto the dielectric layer to form a dielectric layer. The dielectric layer and the dielectric layer are stacked together with a total dielectric layer thickness of 30μm. After water pressure and slicing, the green fabric is manufactured. Step 5: Degrease, sinter, and end-attach the green blank to obtain the base metal high-voltage multilayer ceramic capacitor.

[0010] Further, step one specifically includes: preparing BT material, magnesium oxide, and yttrium oxide according to the formula, and sand milling with zirconia balls as the grinding medium and deionized water as the dispersion medium for 2-12 hours. Then, drying, pulverizing, and sieving are carried out, and solid-state synthesis is performed at a synthesis temperature of 1000-1200℃ and a holding time of 1-4 hours to obtain the BMYT matrix.

[0011] Further, step two specifically includes: preparing sodium carbonate and niobium pentoxide according to the formula, and sand milling with zirconia balls as the grinding medium and deionized water as the dispersion medium for 2-12 hours, followed by drying, pulverizing, and sieving, and then synthesizing using the solid-state method at a synthesis temperature of 900-1100℃ and a holding time of 1-4 hours to obtain NN material.

[0012] Furthermore, in step five, sintering specifically includes: sintering the degreased green body in a reducing atmosphere, introducing H2 / N2 during the sintering process, humidifying simultaneously, raising the temperature to 1200-1300℃ at a rate of 2-10℃ / min and holding for 1-5 hours; subsequently, reoxygenating at 800-1000℃ with an oxygen content of 5-50ppm and holding for 1-6 hours.

[0013] Furthermore, in step five, the end-attachment specifically includes: chamfering the sintered green blank and attaching it with copper electrodes at a sintering temperature of 750-900℃, using nitrogen protection, holding it at that temperature for 0.5-2 hours, and then cooling it to obtain the base metal high-voltage multilayer ceramic capacitor.

[0014] Furthermore, in step five, the environment for degreasing the green body is: 270-400℃, under a nitrogen atmosphere, for 6-30 hours.

[0015] As can be seen from the above description of the present invention, compared with the prior art, the beneficial effects of the present invention are: First, this invention, through the raw material composition and preparation method of ceramic capacitors, enables the prepared ceramic capacitors to possess excellent properties such as high dielectric constant (≥3000), high withstand voltage (breakdown electric field ≥80V / μm), stable dielectric temperature characteristic curve (meeting X7R requirements), low loss (≤2%), high insulation resistance (RC@25℃≥3000 MΩ·μF, RC@125℃≥300 MΩ·μF), and long-term high voltage reliability under high dielectric thickness (30μm before firing). Second, using BMYT material as the main substrate improves the uniformity of the structure and electrical properties. By pre-doping barium titanate with Mg and Y elements with low diffusion rates, a shell can be pre-formed on the barium titanate grains. In the subsequent secondary doping and sintering process, it is ensured that the grains can form a uniform "shell-core" structure, preventing abnormal grain growth. It has a more stable capacitance-temperature curve, higher withstand voltage and insulation resistance than traditional barium titanate. Third, NN material was used as the doping phase, which promoted the sintering of the system and improved the performance of the formulation. NN material has the characteristics of high breakdown field strength, low sintering temperature and high Curie temperature. When combined with the pre-doped BMYT matrix with a "shell-core" structure, NN material forms a sodium niobate second phase at the grain boundary during the sintering process, which can effectively reduce the sintering temperature, improve the voltage resistance and improve the long-term high voltage reliability. Fourth, by employing multi-element synergistic doping and limiting the doping elements and their amounts, targeted A / B site substitution was performed on the host matrix, achieving the system's resistance to reduction and excellent electrical properties. Specifically, Sr and Ca elements primarily underwent A-site substitution, resulting in a dispersed phase transition that improved the material's temperature stability. Particularly in barium titanate, the addition of Sr caused a partial lattice transformation to a cubic crystal system, allowing the material to withstand higher electric field strengths with minimal sacrifice in dielectric constant. Mn and Zr elements primarily underwent B-site substitution, suppressing the presence of Ti in the crystal. 4+ The reduction of ions gives the system good resistance to reduction and reduces losses; while rare earth elements can act as zwitterions to perform adaptive substitution at the A / B sites in the doping system, improve the stability of the formulation, and further enhance the voltage and temperature stability. Fifth, the use of a sintering aid-free system forms a grain structure with closed micropores, achieving high voltage resistance of the system. Although the addition of sintering aids such as SiO2 can effectively reduce the sintering temperature, it can easily lead to uneven grain growth, SiO2 segregation, and phase transformation stress, which is not conducive to voltage resistance and long-term reliability. The formulation system does not add traditional sintering aids such as SiO2 or glass frit, and retains a certain number of closed micropores during sintering, which can avoid abnormal grain growth, reduce ceramic stress, and thus improve voltage resistance and long-term reliability. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the internal structure of the base metal plaster multilayer ceramic capacitor prepared according to the present invention. Figure 2 This is a graph showing the dielectric constant of a base metal high-voltage multilayer ceramic capacitor as a function of temperature, as shown in Example 1. Figure 3 This is a graph showing the capacitance change rate as a function of temperature for a base metal high-voltage multilayer ceramic capacitor, as shown in Example 1. Figure 4 This is a SEM image of the microstructure of a cross-section of a base metal high-voltage multilayer ceramic capacitor in Example 1. In the figure, 1-dielectric layer, 2-electrode. Detailed Implementation

[0017] The present invention will be further described below through specific embodiments.

[0018] A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers together. (See also...) Figure 1 As shown, the dielectric layer includes a dielectric layer 1 and electrodes 2 printed on the dielectric layer 1.

[0019] The dielectric layer comprises the following molar amounts of raw materials: 100 parts of BMYT matrix, 0.2-1.0 parts of NN material, 0.5-1.5 parts of magnesium oxide, 0.05-0.2 parts of manganese tetroxide, 0.2-1.0 parts of zirconium dioxide, 0.2-1.0 parts of calcium carbonate, 0.2-1.0 parts of strontium carbonate, and 0.2-2.0 parts of rare earth oxides; wherein the rare earth oxides are one or more of ytterbium oxide, erbium oxide, and holmium oxide.

[0020] The BMYT matrix comprises the following molar amounts of raw materials: 100 parts of BT material, 0.5-1.5 parts of magnesium oxide, and 0.5-3.0 parts of yttrium oxide; wherein the BT material is barium titanate powder with an average particle size of 500 nm.

[0021] The NN material is composed of sodium carbonate and niobium pentoxide in a molar ratio of 2:1.

[0022] Its preparation method includes the following steps: Step 1: Solid-state synthesis of BMYT matrix: BT material, magnesium oxide, and yttrium oxide are prepared according to the formula. They are then sand-milled using zirconia balls as the grinding medium and deionized water as the dispersion medium for 2-12 hours. After that, the mixture is dried, pulverized, and sieved. The solid-state synthesis is then carried out at a temperature of 1000-1200℃ and a holding time of 1-4 hours to obtain the BMYT matrix. Step 2: Solid-state synthesis of NN material; Sodium carbonate and niobium pentoxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 2-12 hours. Then, the mixture is dried, pulverized, and sieved. The solid-state synthesis is carried out at a synthesis temperature of 900-1100℃ and a holding time of 1-4 hours to obtain NN material. Step 3, Preparation of Casting Slurry: Add ethanol, toluene, and dispersant to a sand mill, then add BMYT matrix, NN material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, strontium carbonate, and rare earth oxides according to the formula. Stir for 2-4 hours and sand mill for 2-6 hours. Then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2-4 hours and sand mill for 2-6 hours to grind the average particle size to 300 nm. Filter and defoam to obtain the casting slurry. The weight ratio of BMYT matrix: ethanol: toluene: dispersant is 100:15-35:15-35:0.5-2, and the ratio of BMYT matrix: dioctyl phthalate: polyvinyl butyral resin is 100:1-5:6-10. Step 4, Green Fabrication: The slurry is cast into a dielectric layer with a thickness of 10μm. Then, nickel electrode slurry is printed onto the dielectric layer to form a dielectric layer. The dielectric layer and the dielectric layer are stacked together with a total dielectric layer thickness of 30μm. After water pressure and slicing, the green fabric is manufactured. Step 5, Degreasing: Degrease the green body. The degreasing environment for the green body is: 270-400℃, under nitrogen atmosphere, for 6-30 hours. Step 6, sintering: Sinter the degreased green body in a reducing atmosphere, introducing H2 / N2 and humidifying it during the sintering process, raising the temperature to 1200-1300℃ at a rate of 2-10℃ / min and holding it for 1-5 hours; then re-oxygenating at 800-1000℃ with an oxygen content of 5-50ppm and holding for 1-6 hours. Step 7, End Attachment: The sintered green blank is chamfered and copper electrodes are attached. The sintering temperature is 750-900℃, nitrogen protection is used, and the temperature is maintained for 0.5-2 hours. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained.

[0023] Example 1 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers together. (See also...) Figure 1 The dielectric layer includes a dielectric layer 1 and electrodes 2 printed on the dielectric layer 1.

[0024] The dielectric layer comprises the following molar amounts of raw materials: 100 parts of BMYT matrix, 0.5 parts of NN material, 1.0 part of magnesium oxide, 0.1 parts of manganese tetroxide, 0.5 parts of zirconium dioxide, 0.5 parts of calcium carbonate, 0.5 parts of strontium carbonate, and 0.5 parts of erbium oxide.

[0025] The BMYT matrix comprises the following molar amounts of raw materials: 100 parts of BT material, 1.0 part of magnesium oxide, and 1.0 part of yttrium oxide; wherein the BT material is barium titanate powder with an average particle size of 500 nm.

[0026] The NN material is composed of sodium carbonate and niobium pentoxide in a molar ratio of 2:1.

[0027] Its preparation method includes the following steps: Step 1, solid-state synthesis of BMYT matrix: BT material, magnesium oxide and yttrium oxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized and sieved. Solid-state synthesis is carried out at a synthesis temperature of 1100℃ and a holding time of 2 hours to obtain the BMYT matrix. Step 2, solid-state synthesis of NN material: Sodium carbonate and niobium pentoxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized, and sieved. The solid-state method is used for synthesis at a temperature of 1000℃ and a holding time of 2 hours to obtain NN material. Step 3, Preparation of Casting Slurry: Ethanol, toluene, and dispersant are added to a sand mill. Then, BMYT matrix, NN material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, strontium carbonate, and rare earth oxides are added according to the formula. Stir for 2 hours and sand mill for 4 hours. Then, dioctyl phthalate and polyvinyl butyral resin are added according to the weight ratio. Stir for 2 hours and sand mill for 4 hours to grind the average particle size to 300 nm. Filter and defoam to obtain the casting slurry. The weight ratio of BMYT matrix: ethanol: toluene: dispersant is 100:30:30:1, and the ratio of BMYT matrix: dioctyl phthalate: polyvinyl butyral resin is 100:3:7.5. Step 4, Green Fabrication: The slurry is cast into a dielectric layer with a thickness of 10μm. Then, nickel electrode slurry is printed onto the dielectric layer to form a dielectric layer. The dielectric layer and the dielectric layer are stacked together with a total dielectric layer thickness of 30μm. After water pressure and slicing, the green fabric is manufactured. Step 5, Degreasing: Degrease the green body in an environment of 350℃ under nitrogen atmosphere for 10 hours. Step 6, sintering: The degreased green body is sintered in a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1250℃ at a rate of 5℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 10ppm and held for 4 hours. Step 7, End attachment: The sintered green blank is chamfered and copper electrodes are used for attachment. The attachment temperature is 850℃, nitrogen protection is used, and the temperature is maintained for 1 hour. After cooling, the base metal high voltage multilayer ceramic capacitor is obtained.

[0028] Example 2 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers together. (See also...) Figure 1 The dielectric layer includes a dielectric layer 1 and electrodes 2 printed on the dielectric layer 1.

[0029] The dielectric layer comprises the following molar amounts of raw materials: 100 parts of BMYT matrix, 0.2 parts of NN material, 0.5 parts of magnesium oxide, 0.05 parts of manganese tetroxide, 0.2 parts of zirconium dioxide, 0.2 parts of calcium carbonate, 0.2 parts of strontium carbonate, and 0.5 parts of holmium oxide.

[0030] The BMYT matrix comprises the following molar amounts of raw materials: 100 parts of BT material, 0.5 parts of magnesium oxide, and 0.5 parts of yttrium oxide, wherein the BT material is barium titanate powder with an average particle size of 500 nm.

[0031] The NN material is composed of sodium carbonate and niobium pentoxide in a molar ratio of 2:1.

[0032] Its preparation method includes the following steps: Step 1, solid-state synthesis of BMYT matrix: BT material, magnesium oxide and yttrium oxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized and sieved. Solid-state synthesis is carried out at a synthesis temperature of 1100℃ and a holding time of 2 hours to obtain the BMYT matrix. Step 2, solid-state synthesis of NN material: Sodium carbonate and niobium pentoxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized, and sieved. The solid-state method is used for synthesis at a temperature of 1000℃ and a holding time of 2 hours to obtain NN material. Step 3, Preparation of Casting Slurry: Ethanol, toluene, and dispersant are added to a sand mill. Then, BMYT matrix, NN material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, strontium carbonate, and rare earth oxides are added according to the formula. Stir for 2 hours and sand mill for 4 hours. Then, dioctyl phthalate and polyvinyl butyral resin are added according to the weight ratio. Stir for 2 hours and sand mill for 4 hours to grind the average particle size to 300 nm. Filter and defoam to obtain the casting slurry. The weight ratio of BMYT matrix: ethanol: toluene: dispersant is 100:30:30:1, and the ratio of BMYT matrix: dioctyl phthalate: polyvinyl butyral resin is 100:3:7.5. Step 4, Green Fabrication: The slurry is cast into a dielectric layer with a thickness of 10μm. Then, nickel electrode slurry is printed onto the dielectric layer to form a dielectric layer. The dielectric layer and the dielectric layer are stacked together with a total dielectric layer thickness of 30μm. After water pressure and slicing, the green fabric is manufactured. Step 5, Degreasing: Degrease the green body in an environment of 350℃ under nitrogen atmosphere for 10 hours. Step 6, sintering: The degreased green body is sintered in a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1250℃ at a rate of 5℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 10ppm and held for 4 hours. Step 7, End attachment: The sintered green blank is chamfered and copper electrodes are used for attachment. The attachment temperature is 850℃, nitrogen protection is used, and the temperature is maintained for 1 hour. After cooling, the base metal high voltage multilayer ceramic capacitor is obtained.

[0033] Example 3 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers together. (See also...) Figure 1 The dielectric layer includes a dielectric layer 1 and electrodes 2 printed on the dielectric layer 1.

[0034] The dielectric layer comprises the following molar amounts of raw materials: 100 parts of BMYT matrix, 1.0 part of NN material, 1.5 parts of magnesium oxide, 0.2 parts of manganese tetroxide, 1.0 part of zirconium dioxide, 1.0 part of calcium carbonate, 1.0 part of strontium carbonate, and 0.5 parts of ytterbium oxide.

[0035] The BMYT matrix comprises the following molar amounts of raw materials: 100 parts of BT material, 1.5 parts of magnesium oxide, and 1.5 parts of yttrium oxide, wherein the BT material is barium titanate powder with an average particle size of 500 nm.

[0036] The NN material is composed of sodium carbonate and niobium pentoxide in a molar ratio of 2:1.

[0037] Its preparation method includes the following steps: Step 1, solid-state synthesis of BMYT matrix: BT material, magnesium oxide and yttrium oxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized and sieved. Solid-state synthesis is carried out at a synthesis temperature of 1100℃ and a holding time of 2 hours to obtain the BMYT matrix. Step 2, solid-state synthesis of NN material: Sodium carbonate and niobium pentoxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized, and sieved. The solid-state method is used for synthesis at a temperature of 1000℃ and a holding time of 2 hours to obtain NN material. Step 3, Preparation of Casting Slurry: Ethanol, toluene, and dispersant are added to a sand mill. Then, BMYT matrix, NN material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, strontium carbonate, and rare earth oxides are added according to the formula. Stir for 2 hours and sand mill for 4 hours. Then, dioctyl phthalate and polyvinyl butyral resin are added according to the weight ratio. Stir for 2 hours and sand mill for 4 hours to grind the average particle size to 300 nm. Filter and defoam to obtain the casting slurry. The weight ratio of BMYT matrix: ethanol: toluene: dispersant is 100:30:30:1, and the ratio of BMYT matrix: dioctyl phthalate: polyvinyl butyral resin is 100:3:7.5. Step 4, Green Fabrication: The slurry is cast into a dielectric layer with a thickness of 10μm. Then, nickel electrode slurry is printed onto the dielectric layer to form a dielectric layer. The dielectric layer and the dielectric layer are stacked together with a total dielectric layer thickness of 30μm. After water pressure and slicing, the green fabric is manufactured. Step 5, Degreasing: Degrease the green body in an environment of 350℃ under nitrogen atmosphere for 10 hours. Step 6, sintering: The degreased green body is sintered in a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1250℃ at a rate of 5℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 10ppm and held for 4 hours. Step 7, End attachment: The sintered green blank is chamfered and copper electrodes are used for attachment. The attachment temperature is 850℃, nitrogen protection is used, and the temperature is maintained for 1 hour. After cooling, the base metal high voltage multilayer ceramic capacitor is obtained.

[0038] Comparative Example 1 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers together. (See also...) Figure 1 The dielectric layer includes a dielectric layer 1 and electrodes 2 printed on the dielectric layer 1.

[0039] The dielectric layer comprises the following molar amounts of raw materials: 100 parts of BT material, 0.5 parts of NN material, 1.0 part of magnesium oxide, 0.1 parts of manganese tetroxide, 0.5 parts of zirconium dioxide, 0.5 parts of calcium carbonate, 0.5 parts of strontium carbonate, and 0.5 parts of erbium oxide; wherein the BT material is barium titanate powder with an average particle size of 500 nm.

[0040] The NN material is composed of sodium carbonate and niobium pentoxide in a molar ratio of 2:1.

[0041] Its preparation method includes the following steps: Step 1, solid-state synthesis of NN material: Sodium carbonate and niobium pentoxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized, and sieved. The solid-state method is used for synthesis at a temperature of 1000℃ and a holding time of 2 hours to obtain NN material. Step 2, Preparation of Casting Slurry: Ethanol, toluene, and dispersant are added to a sand mill. Then, BT material, NN material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, strontium carbonate, and rare earth oxides are added according to the formula. The mixture is stirred for 2 hours and sand milled for 4 hours. Next, dioctyl phthalate and polyvinyl butyral resin are added according to the weight ratio. The mixture is stirred for 2 hours and sand milled for 4 hours to grind the average particle size to 300 nm. The mixture is then filtered and defoamed to obtain the casting slurry. The weight ratio of BT material: ethanol: toluene: dispersant is 100:30:30:1, and the weight ratio of BT material: dioctyl phthalate: polyvinyl butyral resin is 100:3:7.5. Step 3, green body manufacturing: The slurry is cast into a dielectric layer with a thickness of 10μm. Then, nickel electrode slurry is printed onto the dielectric layer to form a dielectric layer. The dielectric layer and the dielectric layer are stacked together with a total dielectric layer thickness of 30μm. After water pressing and slicing, the green body is manufactured. Step 4, Degreasing: Degrease the green body in an environment of 350℃ under nitrogen atmosphere for 10 hours. Step 5, sintering: The degreased green body is sintered in a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1250℃ at a rate of 5℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 10ppm and held for 4 hours. Step 6, End attachment: The sintered green blank is chamfered and copper electrodes are used for attachment. The attachment temperature is 850℃, nitrogen protection is used, and the temperature is maintained for 1 hour. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained.

[0042] Comparative Example 2 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers together. (See also...) Figure 1 The dielectric layer includes a dielectric layer 1 and electrodes 2 printed on the dielectric layer 1.

[0043] The dielectric layer comprises the following molar amounts of raw materials: 100 parts of BT material, 0.5 parts of NN material, 2.0 parts of magnesium oxide, 1.0 part of yttrium oxide, 0.1 parts of manganese tetroxide, 0.5 parts of zirconium dioxide, 0.5 parts of calcium carbonate, 0.5 parts of strontium carbonate, and 0.5 parts of erbium oxide; wherein the BT material is barium titanate powder with an average particle size of 500 nm.

[0044] The NN material is composed of sodium carbonate and niobium pentoxide in a molar ratio of 2:1.

[0045] Its preparation method includes the following steps: Step 1, solid-state synthesis of NN material: Sodium carbonate and niobium pentoxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized, and sieved. The solid-state method is used for synthesis at a temperature of 1000℃ and a holding time of 2 hours to obtain NN material. Step 2, Preparation of Casting Slurry: Ethanol, toluene, and dispersant are added to a sand mill. Then, BT material, NN material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, strontium carbonate, and rare earth oxides are added according to the formula. The mixture is stirred for 2 hours and sand milled for 4 hours. Next, dioctyl phthalate and polyvinyl butyral resin are added according to the weight ratio. The mixture is stirred for 2 hours and sand milled for 4 hours to grind the average particle size to 300 nm. The mixture is then filtered and defoamed to obtain the casting slurry. The weight ratio of BT material: ethanol: toluene: dispersant is 100:30:30:1, and the weight ratio of BT material: dioctyl phthalate: polyvinyl butyral resin is 100:3:7.5. Step 3, green body manufacturing: The slurry is cast into a dielectric layer with a thickness of 10μm. Then, nickel electrode slurry is printed onto the dielectric layer to form a dielectric layer. The dielectric layer and the dielectric layer are stacked together with a total dielectric layer thickness of 30μm. After water pressing and slicing, the green body is manufactured. Step 4, Degreasing: Degrease the green body in an environment of 350℃ under nitrogen atmosphere for 10 hours. Step 5, sintering: The degreased green body is sintered in a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1250℃ at a rate of 5℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 10ppm and held for 4 hours. Step 6, End attachment: The sintered green blank is chamfered and copper electrodes are used for attachment. The attachment temperature is 850℃, nitrogen protection is used, and the temperature is maintained for 1 hour. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained.

[0046] Comparative Example 3 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers together. (See also...) Figure 1 The dielectric layer includes a dielectric layer 1 and electrodes 2 printed on the dielectric layer 1.

[0047] The dielectric layer comprises the following molar amounts of raw materials: 100 parts of BMYT matrix, 1.0 part of magnesium oxide, 0.1 part of manganese tetroxide, 0.5 parts of zirconium dioxide, 0.5 parts of calcium carbonate, 0.5 parts of strontium carbonate, and 0.5 parts of erbium oxide.

[0048] The BMYT matrix comprises the following molar amounts of raw materials: 100 parts of BT material, 1.0 part of magnesium oxide, and 1.0 part of yttrium oxide; wherein the BT material is barium titanate powder with an average particle size of 500 nm.

[0049] Its preparation method includes the following steps: Step 1, solid-state synthesis of BMYT matrix: BT material, magnesium oxide and yttrium oxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized and sieved. Solid-state synthesis is carried out at a synthesis temperature of 1100℃ and a holding time of 2 hours to obtain the BMYT matrix. Step 2, Preparation of Casting Slurry: Ethanol, toluene, and dispersant are added to a sand mill. Then, BMYT matrix, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, strontium carbonate, and rare earth oxides are added according to the formula. The mixture is stirred for 2 hours and sand milled for 4 hours. Then, dioctyl phthalate and polyvinyl butyral resin are added according to the weight ratio. The mixture is stirred for 2 hours and sand milled for 4 hours to grind the average particle size to 300 nm. The mixture is then filtered and defoamed to obtain the casting slurry. The weight ratio of BMYT matrix: ethanol: toluene: dispersant is 100:30:30:1, and the ratio of BMYT matrix: dioctyl phthalate: polyvinyl butyral resin is 100:3:7.5. Step 3, green body manufacturing: The slurry is cast into a dielectric layer with a thickness of 10μm. Then, nickel electrode slurry is printed onto the dielectric layer to form a dielectric layer. The dielectric layer and the dielectric layer are stacked together with a total dielectric layer thickness of 30μm. After water pressing and slicing, the green body is manufactured. Step 4, Degreasing: Degrease the green body in an environment of 350℃ under nitrogen atmosphere for 10 hours. Step 5, sintering: The degreased green body is sintered in a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1250℃ at a rate of 5℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 10ppm and held for 4 hours. Step 6, End attachment: The sintered green blank is chamfered and copper electrodes are used for attachment. The attachment temperature is 850℃, nitrogen protection is used, and the temperature is maintained for 1 hour. After cooling, the base metal high-voltage multilayer ceramic capacitor is obtained.

[0050] Comparative Example 4 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers together. (See also...) Figure 1 The dielectric layer includes a dielectric layer 1 and electrodes 2 printed on the dielectric layer 1.

[0051] The dielectric layer comprises the following molar amounts of raw materials: 100 parts of BMYT matrix, 0.5 parts of NN material, 1.0 part of magnesium oxide, 0.1 parts of manganese tetroxide, 0.5 parts of zirconium dioxide, 0.5 parts of calcium carbonate, 0.5 parts of strontium carbonate, 0.5 parts of erbium oxide, and 0.5 parts of silicon dioxide.

[0052] The BMYT matrix comprises the following molar amounts of raw materials: 100 parts of BT material, 1.0 part of magnesium oxide, and 1.0 part of yttrium oxide; wherein the BT material is barium titanate powder with an average particle size of 500 nm.

[0053] The NN material is composed of sodium carbonate and niobium pentoxide in a molar ratio of 2:1.

[0054] Its preparation method includes the following steps: Step 1, solid-state synthesis of BMYT matrix: BT material, magnesium oxide and yttrium oxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized and sieved. Solid-state synthesis is carried out at a synthesis temperature of 1100℃ and a holding time of 2 hours to obtain the BMYT matrix. Step 2, solid-state synthesis of NN material: Sodium carbonate and niobium pentoxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized, and sieved. The solid-state method is used for synthesis at a temperature of 1000℃ and a holding time of 2 hours to obtain NN material. Step 3, Preparation of Casting Slurry: Ethanol, toluene, and dispersant are added to a sand mill. Then, BMYT matrix, NN material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, strontium carbonate, rare earth oxides, and silicon dioxide are added according to the formula. Stir for 2 hours and sand mill for 4 hours. Then, dioctyl phthalate and polyvinyl butyral resin are added according to the weight ratio. Stir for 2 hours and sand mill for 4 hours to grind the average particle size to 300 nm. Filter and defoam to obtain the casting slurry. The weight ratio of BMYT matrix: ethanol: toluene: dispersant is 100:30:30:1, and the ratio of BMYT matrix: dioctyl phthalate: polyvinyl butyral resin is 100:3:7.5. Step 4, Green Fabrication: The slurry is cast into a dielectric layer with a thickness of 10μm. Then, nickel electrode slurry is printed onto the dielectric layer to form a dielectric layer. The dielectric layer and the dielectric layer are stacked together with a total dielectric layer thickness of 30μm. After water pressure and slicing, the green fabric is manufactured. Step 5, Degreasing: Degrease the green body in an environment of 350℃ under nitrogen atmosphere for 10 hours. Step 6, sintering: The degreased green body is sintered in a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1250℃ at a rate of 5℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 10ppm and held for 4 hours. Step 7, End attachment: The sintered green blank is chamfered and copper electrodes are used for attachment. The attachment temperature is 850℃, nitrogen protection is used, and the temperature is maintained for 1 hour. After cooling, the base metal high voltage multilayer ceramic capacitor is obtained.

[0055] Comparative Example 5 A base metal high-voltage multilayer ceramic capacitor is formed by stacking and firing dielectric layers together. (See also...) Figure 1 The dielectric layer includes a dielectric layer 1 and electrodes 2 printed on the dielectric layer 1.

[0056] The dielectric layer comprises the following molar amounts of raw materials: 100 parts of BMYT matrix, 0.5 parts of NN material, 1.0 part of magnesium oxide, 0.1 parts of manganese tetroxide, 0.5 parts of zirconium dioxide, 0.5 parts of calcium carbonate, and 0.5 parts of erbium oxide.

[0057] The BMYT matrix comprises the following molar amounts of raw materials: 100 parts of BT material, 1.0 part of magnesium oxide, and 1.0 part of yttrium oxide; wherein the BT material is barium titanate powder with an average particle size of 500 nm.

[0058] The NN material is composed of sodium carbonate and niobium pentoxide in a molar ratio of 2:1.

[0059] Its preparation method includes the following steps: Step 1, solid-state synthesis of BMYT matrix: BT material, magnesium oxide and yttrium oxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized and sieved. Solid-state synthesis is carried out at a synthesis temperature of 1100℃ and a holding time of 2 hours to obtain the BMYT matrix. Step 2, solid-state synthesis of NN material: Sodium carbonate and niobium pentoxide are prepared according to the formula, and sand milled with zirconia balls as grinding media and deionized water as dispersion media for 6 hours. Then, the mixture is dried, pulverized, and sieved. The solid-state method is used for synthesis at a temperature of 1000℃ and a holding time of 2 hours to obtain NN material. Step 3, Preparation of Casting Slurry: Ethanol, toluene, and dispersant are added to a sand mill. Then, BMYT matrix, NN material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, and rare earth oxides are added according to the formula. Stir for 2 hours and sand mill for 4 hours. Then, dioctyl phthalate and polyvinyl butyral resin are added according to the weight ratio. Stir for 2 hours and sand mill for 4 hours to grind the average particle size to 300 nm. Filter and defoam to obtain the casting slurry. The weight ratio of BMYT matrix: ethanol: toluene: dispersant is 100:30:30:1, and the ratio of BMYT matrix: dioctyl phthalate: polyvinyl butyral resin is 100:3:7.5. Step 4, Green Fabrication: The slurry is cast into a dielectric layer with a thickness of 10μm. Then, nickel electrode slurry is printed onto the dielectric layer to form a dielectric layer. The dielectric layer and the dielectric layer are stacked together with a total dielectric layer thickness of 30μm. After water pressure and slicing, the green fabric is manufactured. Step 5, Degreasing: Degrease the green body in an environment of 350℃ under nitrogen atmosphere for 10 hours. Step 6, sintering: The degreased green body is sintered in a reducing atmosphere. During the sintering process, H2 / N2 is introduced and humidified at the same time. The temperature is increased to 1250℃ at a rate of 5℃ / min and held for 2 hours. Then, oxygen is restored at 900℃ with an oxygen content of 10ppm and held for 4 hours. Step 7, End attachment: The sintered green blank is chamfered and copper electrodes are used for attachment. The attachment temperature is 850℃, nitrogen protection is used, and the temperature is maintained for 1 hour. After cooling, the base metal high voltage multilayer ceramic capacitor is obtained.

[0060] The capacitors prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to various performance tests, and the results are shown in Table 1. Simultaneously, the base metal high-voltage multilayer ceramic capacitor obtained in Example 1 was subjected to corresponding tests. Figure 2 This is a graph showing the dielectric constant of a base metal high-voltage multilayer ceramic capacitor as a function of temperature, as shown in Example 1. Figure 3 This is a graph showing the capacitance change rate as a function of temperature for a base metal high-voltage multilayer ceramic capacitor, as shown in Example 1. Figure 4 This is a SEM image of the microstructure of a cross-section of a base metal high-voltage multilayer ceramic capacitor in Example 1. Table 1 Test Results of Each Embodiment Through the above table and appendix Figure 2 , 3As can be seen from section 4, the base metal high-voltage multilayer ceramic capacitor prepared in this application is synthesized by solid-state method with BMYT main matrix and NN material, and doped with NN material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, strontium carbonate and rare earth oxides in BMYT main matrix. Under the condition of high dielectric thickness, it has obtained high dielectric constant, low loss, high withstand voltage, high insulation resistance, good temperature stability and long-term high voltage reliability.

[0061] A comparison of Example 1 and Comparative Examples 1-5 shows that by limiting the synthesis of the BMYT substrate and coordinating the various dopants, it is possible to obtain superior performances such as a high dielectric constant (≥3000), a stable dielectric temperature characteristic curve (meeting X7R requirements), low loss (≤2%), high withstand voltage (breakdown electric field ≥80V / μm), high insulation resistance (RC@25℃≥3000 MΩ·μF, RC@125℃≥300 MΩ·μF), and good long-term high voltage reliability (RC@25℃≥2000 MΩ·μF after HALT, RC@125℃≥200 MΩ·μF after HALT) under the premise of high dielectric thickness (30μm before calcination).

[0062] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A base metal high-voltage multilayer ceramic capacitor, formed by stacking and firing dielectric layers, wherein each dielectric layer includes a dielectric layer and electrodes printed on the dielectric layer, characterized in that: The dielectric layer comprises the following molar amounts of raw materials: 100 parts of BMYT matrix, 0.2-1.0 parts of NN material, 0.5-1.5 parts of magnesium oxide, 0.05-0.2 parts of manganese tetroxide, 0.2-1.0 parts of zirconium dioxide, 0.2-1.0 parts of calcium carbonate, 0.2-1.0 parts of strontium carbonate, and 0.2-2.0 parts of rare earth oxides; The BMYT matrix comprises the following molar amounts of raw materials: 100 parts BT material, 0.5-1.5 parts magnesium oxide, and 0.5-3.0 parts yttrium oxide; The NN material is composed of sodium carbonate and niobium pentoxide in a molar ratio of 2:

1.

2. The base metal high-voltage multilayer ceramic capacitor according to claim 1, characterized in that: The rare earth oxide is one or more of ytterbium oxide, erbium oxide, and holmium oxide.

3. The base metal high-voltage multilayer ceramic capacitor according to claim 1, characterized in that: The BT material is barium titanate powder with an average particle size of 500 nm.

4. A method for preparing a base metal high-voltage multilayer ceramic capacitor according to any one of claims 1 to 3, characterized in that: Includes the following steps: Step 1: Solid-state synthesis of BMYT matrix; Step 2: Solid-state synthesis of NN materials; Step 3, Preparation of Casting Slurry: Add ethanol, toluene, and dispersant to a sand mill, then add BMYT matrix, NN material, magnesium oxide, manganese tetroxide, zirconium dioxide, calcium carbonate, strontium carbonate, and rare earth oxides according to the formula. Stir for 2-4 hours and sand mill for 2-6 hours. Then add dioctyl phthalate and polyvinyl butyral resin according to the weight ratio, stir for 2-4 hours and sand mill for 2-6 hours to grind the average particle size to 300 nm. Filter and defoam to obtain the casting slurry. The weight ratio of BMYT matrix: ethanol: toluene: dispersant is 100:15-35:15-35:0.5-2, and the ratio of BMYT matrix: dioctyl phthalate: polyvinyl butyral resin is 100:1-5:6-10. Step 4, Green Fabrication: The slurry is cast into a dielectric layer with a thickness of 10μm. Then, nickel electrode slurry is printed onto the dielectric layer to form a dielectric layer. The dielectric layer and the dielectric layer are stacked together with a total dielectric layer thickness of 30μm. After water pressure and slicing, the green fabric is manufactured. Step 5: Degrease, sinter, and end-attach the green blank to obtain the base metal high-voltage multilayer ceramic capacitor.

5. The method for preparing a base metal high-voltage multilayer ceramic capacitor according to claim 4, characterized in that: Step one specifically includes: preparing BT material, magnesium oxide, and yttrium oxide according to the formula, and sand milling with zirconia balls as the grinding medium and deionized water as the dispersion medium for 2-12 hours. Then, drying, pulverizing, and sieving are carried out, and solid-state synthesis is performed at a synthesis temperature of 1000-1200℃ and a holding time of 1-4 hours to obtain the BMYT matrix.

6. The method for preparing a base metal high-voltage multilayer ceramic capacitor according to claim 4, characterized in that: Step two specifically includes: preparing sodium carbonate and niobium pentoxide according to the formula, sand milling with zirconia balls as the grinding medium and deionized water as the dispersion medium for 2-12 hours, followed by drying, pulverizing, and sieving, and then synthesizing using the solid-state method at a synthesis temperature of 900-1100℃ and a holding time of 1-4 hours to obtain NN material.

7. The method for preparing a base metal high-voltage multilayer ceramic capacitor according to claim 4, characterized in that: Step five, sintering specifically includes: sintering the degreased green body in a reducing atmosphere, introducing H2 / N2 during the sintering process, humidifying simultaneously, raising the temperature to 1200-1300℃ at a rate of 2-10℃ / min and holding for 1-5 hours; then re-oxygenating at 800-1000℃ with an oxygen content of 5-50ppm and holding for 1-6 hours.

8. The method for preparing a base metal high-voltage multilayer ceramic capacitor according to claim 4, characterized in that: Step five, specifically the end-attachment, includes: chamfering the sintered green blank and attaching it with copper electrodes at a sintering temperature of 750-900℃, using nitrogen protection, holding it at that temperature for 0.5-2 hours, and then cooling it to obtain the base metal high-voltage multilayer ceramic capacitor.

9. The method for preparing a base metal high-voltage multilayer ceramic capacitor according to claim 4, characterized in that: In step five, the degreasing environment for the green body is: 270-400℃, under a nitrogen atmosphere, for 6-30 hours.

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