A combined dielectric high-voltage multilayer ceramic capacitor and a preparation process thereof

Abstract

The application discloses a combined medium high-voltage multilayer porcelain dielectric capacitor and a preparation process thereof. The multilayer porcelain dielectric capacitor is prepared by stacking and firing a plurality of combined dielectric layers. The combined dielectric layers are stacked in the order of dielectric layer B, medium layer A and dielectric layer B to form a BAB structure. The dielectric layer B comprises a medium layer B and an electrode printed on the medium layer B. The medium layer A comprises the following raw materials: a barium titanate matrix A and a liquid modified dopant A. The liquid modified dopant A comprises the following raw materials: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and SLV material. The porcelain dielectric capacitor prepared by the ceramic material defined in the application has excellent performances such as high dielectric constant (>=4500), smooth dielectric temperature characteristic curve (X7R requirement is met), low loss (<=3.0%), high insulation resistance (RC@25 DEG C >=5000 M omega*mu F), high voltage resistance (>150 V / um) and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of porcelain dielectric capacitor preparation, and particularly relates to a combined dielectric high-voltage multilayer porcelain dielectric capacitor and a preparation process thereof. BACKGROUND

[0002] Chip multilayer ceramic capacitors (MLCC for short) are new electronic components and occupy an absolute dominant position in the field of capacitors, and are widely used in various electronic circuits. With the popularization and upgrading of electronic products, low cost, high capacity and high voltage are the main development direction of chip multilayer ceramic capacitors, and the demand for low-cost base metal high-voltage MLCC is increasing year by year.

[0003] The base metal high-voltage MLCC generally uses barium titanate as the base and nickel as the internal electrode, which can effectively reduce the cost compared with the traditional noble metal high-voltage MLCC. Since the base metal will be oxidized when sintered in air atmosphere, it needs to be sintered in a reducing atmosphere. However, barium titanate will be reduced and semiconductized when sintered in a reducing atmosphere, resulting in low insulation resistance and poor reliability. Therefore, it is necessary to dope and modify the barium titanate to make the ceramic material have good electrical properties and reliability.

[0004] The challenge of doping and modifying the base metal high-voltage MLCC ceramic material lies in how to obtain high voltage resistance, high insulation resistance and high dielectric constant while having good temperature stability, which is often difficult to achieve through the doping and modification of a single medium. Therefore, it is necessary to optimize the internal structure of the base metal high-voltage MLCC to realize the excellent performance of the combined medium. Through the optimization of the internal structure of the MLCC, the performance of the ceramic material can be maximized, which is the problem to be solved by the application. SUMMARY

[0005] The application aims to overcome the shortcomings of the prior art and provide a combined dielectric high-voltage multilayer porcelain dielectric capacitor and a preparation process thereof.

[0006] The application adopts the following technical scheme:

[0007] A combined dielectric high-voltage multilayer porcelain dielectric capacitor is formed by sintering a plurality of combined dielectric layers on each other, the internal structure of the combined dielectric layer is formed by stacking the dielectric layer B, the dielectric layer A and the dielectric layer B in the order of BAB, and the dielectric layer B comprises a dielectric layer B and an electrode printed on the dielectric layer B.

[0008] The dielectric layer A comprises the following raw materials by weight: 100 parts of barium titanate base A, 1.409-6.315 parts of liquid modified dopant A.

[0009] Liquid modified dopant A, composed of magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide, SLV material in the proportion of 0.086-0.259:0.069-0.128:0.320-1.620:0.484-2.535:0.085-0.423:0.158-0.317:0.13-1.34 by weight ratio;

[0010] The SLV material is synthesized from silicon dioxide, lithium carbonate and vanadium pentoxide in a molar ratio of 2.00:1.00:0.50.

[0011] Further, the rare earth oxide a is one or both of dysprosium oxide and holmium oxide, and the rare earth oxide b is one or both of yttrium oxide and ytterbium oxide.

[0012] Further, the medium layer B comprises the following raw materials by weight: 100 parts of barium titanate matrix B, 1.615-6.597 parts of liquid modified dopant B.

[0013] Further, the liquid modified dopant B is composed of magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate, and zirconium dioxide in the proportion of 0.518-1.037:0.029-0.069:0.008-0.078:0.320-1.620:0.484-2.535:0.129-0.515:0.021-0.215:0.106-0.528 by weight ratio.

[0014] Further, the rare earth oxide c is one or both of dysprosium oxide and holmium oxide, and the rare earth oxide d is one or both of yttrium oxide and ytterbium oxide.

[0015] Further, the particle size of the barium titanate matrix A is 300-800 nm, and the particle size of the barium titanate matrix B is 100-300 nm.

[0016] Further, the thickness of the medium layer A is 50 um, and the thickness of the medium layer B is 5 um.

[0017] A preparation process of a combined medium high-voltage multilayer ceramic dielectric capacitor, comprising the following steps:

[0018] Step one, synthesis of SLV material: silica, lithium carbonate, and vanadium pentoxide are added to a sand mill in the specified ratio, and sand milling is performed for 2-8 hours with pure water as the medium. After drying and crushing, calcination is performed at 500-700°C. After calcination, the material is ground in a sand mill with pure water as the medium to a particle size of less than 300 nm. After drying and crushing, the SLV material is obtained.

[0019] Step two, preparation of liquid modified dopant A: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and the SLV material prepared in step one are added into a sand mill in a proportioning manner, and are ground in an alcohol medium to a particle size of less than 300 nm to obtain the liquid modified dopant A;

[0020] Step three, preparation of the casting slurry A: a dispersing agent and the liquid modified dopant A are added into an ethanol and toluene solvent, and then barium titanate matrix A is added and ground for 1.5 h; dioctyl phthalate and polyvinyl butyral resin are added and stirred for 2 h, and ball-milled for 3 h; and then filtration, vacuum degassing are performed to obtain the casting slurry A;

[0021] Step four, preparation of the liquid modified dopant B;

[0022] Step five, preparation of the casting slurry B;

[0023] Step six, green body manufacturing: the casting slurry A is cast into a medium layer A with a casting thickness of 50 μm; the casting slurry B is cast into a medium layer B with a casting thickness of 5 μm; then a nickel electrode slurry is printed onto the medium layer B to form a dielectric layer B, and the dielectric layer B, the medium layer A and the medium layer B are stacked in sequence to form a BAB structure, and then water pressure and slicing are performed to manufacture a green body;

[0024] Step seven, the green body manufactured in step four is sequentially subjected to a degreasing, sintering, chamfering, end copper and sintering process to obtain the combined dielectric high-voltage multilayer ceramic capacitor.

[0025] Further, the specific operation of step four, preparation of the liquid modified dopant B, is as follows: magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate and zirconium dioxide are added into a sand mill in a proportioning manner, and are ground in an alcohol medium to a particle size of less than 300 nm to obtain the liquid modified dopant B.

[0026] Further, the specific operation of step five, preparation of the casting slurry B, is as follows: a dispersing agent and the liquid modified dopant B are added into an ethanol and toluene solvent, and then barium titanate matrix B is added and ground for 1.5 h; dioctyl phthalate and polyvinyl butyral resin are added and stirred for 2 h, and ball-milled for 3 h; and then filtration, vacuum degassing are performed to obtain the casting slurry B.

[0027] From the above description of the present application, it can be known that, compared with the prior art, the present application has the following beneficial effects:

[0028] First, the porcelain dielectric capacitor prepared by the ceramic material defined in the application has excellent performances such as high dielectric constant (≥4500), smooth dielectric temperature characteristic curve (meeting the X7R requirement), low loss (≤3.0%), high insulation resistance (RC@25℃≥5000MΩ·μF), high withstand voltage (>150V / μm) and the like;

[0029] Second, the SLV material is synthesized and added into the dielectric A as one of the modified dopants, the lithium carbonate and vanadium pentoxide in the SLV material have low melting points, and a small amount of liquid phase generated during sintering is helpful to the sintering effect of the system, which can effectively reduce the sintering temperature of the ceramic material, improve the density, and thus improve the dielectric constant and withstand voltage performance of the dielectric; meanwhile, the vanadium element in the SLV material as a donor dopant can reduce the compensation oxygen vacancies caused by the acceptor dopant, thereby improving the withstand voltage and reliability of the dielectric; the addition of silicon element can effectively improve the dielectric temperature characteristic of the dielectric, so that the dielectric obtains a smooth dielectric temperature characteristic curve; the dielectric layer A also adds barium element and a large amount of zirconium element: the zirconium element changes the crystal structure, widens the Curie peak, and smooths the dielectric temperature characteristic curve; the barium element has the effect of stabilizing the system, so that the ceramic material can obtain stable performance in a wide sintering temperature range;

[0030] Third, the dielectric B adds excess magnesium element to form a magnesium-rich phase at the grain boundary, increases the grain boundary resistance, makes the dielectric obtain high insulation resistance, introduces more non-ferroelectric phase, and is beneficial to the reduction of dielectric loss; meanwhile, Mg can inhibit the growth of barium titanate ceramic grains, which is beneficial to the formation of fine crystal structure, increases the dielectric grain boundary density, and further improves the insulation resistance, withstand voltage and reliability of the dielectric;

[0031] Fourth, by combining two different dielectric layers, at the two interfaces of medium A, a certain film thickness of medium B is laminated to form a combined dielectric layer of BAB structure, which can make the MLCC have good temperature stability while obtaining high dielectric constant, high insulation resistance and high voltage resistance. Among them, medium A adopts barium titanate matrix with particle size of 300-800 nm, which has high dielectric constant, high voltage resistance and smooth dielectric temperature characteristic curve through doping modification; medium B adopts fine particle barium titanate matrix with particle size of 100-300 nm, so that the dielectric layer has more grains and grain boundaries, and has high insulation resistance and reliability. The casting lamination thickness of medium A is 50 μm, which is the main part of the combined dielectric layer, so the combined dielectric layer inherits its high dielectric constant, good temperature stability and other excellent properties; the casting lamination thickness of medium B is 5 μm, which is the interface between medium A and nickel electrode, the high resistance interface region of the grain boundary and electrode interface of MLCC, which can limit the conduction of electrons and oxygen vacancies in the dielectric layer, and to a large extent, determine the insulation resistance and reliability of the system, so the medium B with high insulation resistance and high reliability as the electrode interface layer can effectively improve the insulation resistance and reliability of the combined dielectric layer as a whole. Through the special combination of dielectric layers with different electrical properties, the excellent electrical properties of each dielectric layer can be effectively integrated to obtain better performance that is difficult to obtain by doping modification of a single dielectric layer, which expands the development idea of barium titanate system MLCC;

[0032] Fifth, medium A and medium B can be co-fired by using similar formula composition and having similar sintering temperature and shrinkage characteristics. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The combined dielectric capacitor provided by the present application Figure 1 ;

[0034] Figure 2 The combined dielectric capacitor provided by the present application Figure 1 ;

[0035] Figure 3 The capacitance change rate of the sample of example 1 changes with temperature

[0036] Figure 4 The dielectric constant of the sample of example 1 changes with temperature

[0037] In the figure, 1 is a ceramic combined dielectric, 2 is a nickel metal inner electrode, and 3 is a copper outer electrode. DETAILED DESCRIPTION

[0038] The present application will be further described below through specific embodiments.

[0039] REFERENCE Figures 1 to 4As shown, a combined dielectric high-voltage multilayer ceramic capacitor is prepared by stacking a plurality of combined dielectric layers, wherein the combined dielectric layers are stacked in the order of dielectric layer B, dielectric layer A, and dielectric layer B to form a BAB structure, and specifically, the dielectric layer B comprises a dielectric layer B and an electrode printed on the dielectric layer B; further, the thickness of the dielectric layer A is 50 um, and the thickness of the dielectric layer B is 5 um.

[0040] The dielectric layer A comprises the following raw materials by weight: 100 parts of barium titanate matrix A, 1.409-6.315 parts of liquid modification dopant A; wherein the particle size of the barium titanate matrix A is 300-800 nm; the liquid modification dopant A is composed of magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide, and SLV material in a weight ratio of 0.086-0.259:0.069-0.128:0.320-1.620:0.484-2.535:0.085-0.423:0.158-0.317:0.13-1.34; specifically, the SLV material is synthesized from silicon dioxide, lithium carbonate, and vanadium pentoxide in a molar ratio of 2.00:1.00:0.50; the rare earth oxide a is one or both of dysprosium oxide and holmium oxide, and the rare earth oxide b is one or both of yttrium oxide and ytterbium oxide.

[0041] The dielectric layer B comprises the following raw materials by weight: 100 parts of barium titanate matrix B, 1.615-6.597 parts of liquid modification dopant B; wherein the particle size of the barium titanate matrix B is 100-300 nm; the liquid modification dopant B is composed of magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate, and zirconium dioxide in a weight ratio of 0.518-1.037:0.029-0.069:0.008-0.078:0.320-1.620:0.484-2.535:0.129-0.515:0.021-0.215:0.106-0.528; specifically, the rare earth oxide c is one or both of dysprosium oxide and holmium oxide, and the rare earth oxide d is one or both of yttrium oxide and ytterbium oxide.

[0042] A preparation process of a combined dielectric high-voltage multilayer ceramic capacitor, comprising the following steps:

[0043] Step one, synthesis of SLV material: silica, lithium carbonate, and vanadium pentoxide are added to a sand mill in a predetermined ratio, and sand milling is performed for 2-8 hours with pure water as the medium; after drying and crushing, calcination is performed at 500-700°C; after calcination, grinding is performed in a sand mill with pure water as the medium to obtain a particle size of less than 300 nm; after drying and crushing, the SLV material is obtained;

[0044] Step two, preparation of liquid modified dopant A: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and the SLV material prepared in step one are added into a sand mill in a proportioning manner, and are ground in an alcohol medium to a particle size of less than 300 nm to obtain the liquid modified dopant A;

[0045] Step three, preparation of the casting slurry A: a dispersing agent and the liquid modified dopant A are added into an ethanol and toluene solvent, and then barium titanate matrix A is added and ground for 1.5 h; dioctyl phthalate and polyvinyl butyral resin are added and stirred for 2 h, and then ball milled for 3 h; the casting slurry A is obtained after filtration, vacuum degassing and the like.

[0046] Step four, preparation of the liquid modified dopant B: magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate and zirconium dioxide are added into a sand mill in a proportioning manner, and are ground in an alcohol medium to a particle size of less than 300 nm to obtain the liquid modified dopant B;

[0047] Step five, preparation of the casting slurry B: a dispersing agent and the liquid modified dopant B are added into an ethanol and toluene solvent, and then barium titanate matrix B is added and ground for 1.5 h; dioctyl phthalate and polyvinyl butyral resin are added and stirred for 2 h, and then ball milled for 3 h; the casting slurry B is obtained after filtration, vacuum degassing and the like.

[0048] Step six, green body manufacturing: the casting slurry A is cast into a medium layer A with a casting thickness of 50 μm; the casting slurry B is cast into a medium layer B with a casting thickness of 5 μm; then a nickel electrode slurry is printed onto the medium layer B to form a dielectric layer B, and the dielectric layer B, the medium layer A and the medium layer B are stacked in sequence to form a BAB structure, and then the green body is manufactured after water pressure and slicing.

[0049] Step seven, the green body manufactured in step four is sequentially subjected to a debinding process, a sintering process, a chamfering process, a copper terminal attaching process and a soldering process to obtain the combined dielectric high-voltage multilayer ceramic capacitor.

[0050] Embodiment 1

[0051] A combined dielectric high-voltage multilayer ceramic capacitor is manufactured by stacking a plurality of combined dielectric layers, wherein the combined dielectric layers are stacked in sequence to form a BAB structure, and the dielectric layer B comprises a medium layer B and an electrode printed on the medium layer B; further, the thickness of the medium layer A is 50 μm, and the thickness of the medium layer B is 5 μm.

[0052] The medium layer A comprises the following raw materials in parts by weight: 100 parts of barium titanate base A, 4.699 parts of liquid modified dopant A; wherein the liquid modified dopant A is composed of magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and SLV material in a proportion of 0.252:0.093:1.249:1.842:0.357:0.204:0.702 by weight ratio; specifically, the SLV material is synthesized from silicon dioxide, lithium carbonate and vanadium pentoxide in a molar ratio of 2.00:1.00:0.50; the rare earth oxide a is holmium oxide, and the rare earth oxide b is ytterbium oxide.

[0053] The medium layer B comprises the following raw materials in parts by weight: 100 parts of barium titanate base B, 5.502 parts of liquid modified dopant B; wherein the liquid modified dopant B is composed of magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate and zirconium dioxide in a proportion of 0.975:0.043:0.025:1.237:2.223:0.497:0.128:0.374 by weight ratio; specifically, the rare earth oxide c is yttrium oxide, and the rare earth oxide d is yttrium oxide.

[0054] A preparation process of a combined medium high-voltage multilayer ceramic dielectric capacitor, comprising the following steps:

[0055] Step one, synthesis of SLV material: silicon dioxide, lithium carbonate and vanadium pentoxide are added into a sand mill in a proportion, and are sand milled for 2 hours with pure water as a medium, and then are dried, crushed, calcined at 700 DEG C, ground in a sand mill with pure water as a medium to a particle size of less than 300 nm, and then are dried and crushed to obtain the SLV material;

[0056] Step two, preparation of liquid modified dopant A: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and the SLV material prepared in step one are added into a sand mill in a proportion, and are ground in a sand mill with alcohol as a medium to a particle size of less than 300 nm to obtain the liquid modified dopant A;

[0057] Step three, preparation of casting slurry A: a dispersing agent and the liquid modified dopant A are added into ethanol and toluene solvents, and then barium titanate base A is added, and is ground for 1.5 hours; dioctyl phthalate and polyvinyl butyral resin are added, and are stirred for 2 hours and ball milled for 3 hours, and then are filtered, vacuumized and defoamed to obtain the casting slurry A;

[0058] Step four, preparation of liquid modified dopant B: magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate and zirconium dioxide are added into a sand mill in a proportion, and are ground in a sand mill with alcohol as a medium to a particle size of less than 300 nm to obtain the liquid modified dopant B.

[0059] Step five, preparation of the casting slurry B: adding dispersant, liquid modified dopant B in ethanol, toluene solvent, then adding barium titanate matrix B, grinding for 1.5h; adding dioctyl phthalate, polyvinyl butyral resin, stirring for 2h, ball milling for 3h, then filtering, vacuum defoaming, obtaining the casting slurry B;

[0060] Step six, green body manufacturing: casting the casting slurry A into the medium layer A, the casting thickness is 50μm; casting the casting slurry B into the medium layer B, the casting thickness is 5μm; then printing the nickel electrode slurry onto the medium layer B to form the dielectric layer B, and stacking them in the order of dielectric layer B, medium layer A, medium layer B, forming the BAB structure, then water pressure, slicing, manufacturing the green body;

[0061] Step seven, the green body manufactured in step four is sequentially subjected to the processes of debinding, sintering, chamfering, end copper, and affixing, obtaining the combined dielectric high-voltage multilayer ceramic capacitor.

[0062] Example 2

[0063] A combined dielectric high-voltage multilayer ceramic capacitor is manufactured by stacking a plurality of combined dielectric layers, wherein the combined dielectric layer is stacked in the order of dielectric layer B, medium layer A, and dielectric layer B to form a BAB structure, specifically, the dielectric layer B comprises the medium layer B and the electrode printed on the medium layer B; further, the thickness of the medium layer A is 50μm, and the thickness of the medium layer B is 5μm.

[0064] The medium layer A comprises the following raw materials by weight: 100 parts of barium titanate matrix A and 4.649 parts of liquid modified dopant A; wherein the liquid modified dopant A is composed of magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide, and SLV material in a weight ratio of 0.202:0.093:1.249:1.842:0.357:0.204:0.702; specifically, the SLV material is synthesized from silicon dioxide, lithium carbonate, and vanadium pentoxide in a molar ratio of 2.00:1.00:0.50; the rare earth oxide a is holmium oxide, and the rare earth oxide b is yttrium oxide.

[0065] The medium layer B comprises the following raw materials by weight: 100 parts of barium titanate matrix B and 5.574 parts of liquid modified dopant B; wherein the liquid modified dopant B is composed of magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate, and zirconium dioxide in a weight ratio of 0.975:0.043:0.025:1.309:2.223:0.497:0.128:0.374; specifically, the rare earth oxide c is dysprosium oxide, and the rare earth oxide d is yttrium oxide.

[0066] A preparation process of a combined dielectric high-voltage multilayer ceramic capacitor, comprising the following steps:

[0067] Step one, synthesis of SLV material: silica, lithium carbonate, vanadium pentoxide are added into a sand mill according to the ratio, and are sand milled for 8h with pure water as the medium, and are dried and crushed, and then are calcined at 500 DEG C, and then are ground in the sand mill with pure water as the medium to a particle size of less than 300nm, and then are dried and crushed to obtain the SLV material;

[0068] Step two, preparation of liquid modified dopant A: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and the SLV material prepared in step one are added into a sand mill according to the ratio, and are ground to a particle size of less than 300nm with alcohol as the medium to obtain the liquid modified dopant A;

[0069] Step three, preparation of flow casting slurry A: a dispersing agent, the liquid modified dopant A, and then barium titanate matrix A are added into ethanol and toluene solvents, and are ground for 1.5h; dioctyl phthalate and polyvinyl butyral resin are added, and are stirred for 2h, and are ball milled for 3h, and then are filtered, vacuumized and defoamed to obtain the flow casting slurry A;

[0070] Step four, preparation of liquid modified dopant B: magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silica, calcium carbonate and zirconium dioxide are added into a sand mill according to the ratio, and are ground to a particle size of less than 300nm with alcohol as the medium to obtain the liquid modified dopant B;

[0071] Step five, preparation of flow casting slurry B: a dispersing agent and the liquid modified dopant B are added into ethanol and toluene solvents, and then barium titanate matrix B is added, and is ground for 1.5h; dioctyl phthalate and polyvinyl butyral resin are added, and are stirred for 2h, and are ball milled for 3h, and then are filtered, vacuumized and defoamed to obtain the flow casting slurry B;

[0072] Step six, green body manufacturing: the flow casting slurry A is flow cast into a dielectric layer A with a flow casting thickness of 50μm; the flow casting slurry B is flow cast into a dielectric layer B with a flow casting thickness of 5μm; then a nickel electrode slurry is printed onto the dielectric layer B to form a dielectric layer B, and the dielectric layer B, the dielectric layer A and the dielectric layer B are stacked in sequence to form a BAB structure, and then are subjected to water pressure and slicing to manufacture a green body;

[0073] Step seven, the green body manufactured in step four is sequentially subjected to the processes of debinding, sintering, chamfering, end coppering and sintering to obtain the combined dielectric high-voltage multilayer ceramic capacitor.

[0074] Example 3

[0075] A kind of combined medium high-voltage multilayer porcelain dielectric capacitor is fired by mutual superposition of multiple combined dielectric layers, wherein, combined dielectric layer is formed by the order of dielectric layer B, dielectric layer A, dielectric layer B inside BAB structure is superimposed, specifically, dielectric layer B includes dielectric layer B and electrode printed on dielectric layer B;Further, the thickness of dielectric layer A is 50um, and the thickness of dielectric layer B is 5um.

[0076] Dielectric layer A includes the following raw materials by weight: 100 parts of barium titanate matrix A, 4.910 parts of liquid modified dopant A;Liquid modified dopant A is composed of magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide, SLV material in a weight ratio of 0.202:0.093:1.249:2.103:0.357:0.204:0.702;Specifically, the SLV material is synthesized from silicon dioxide, lithium carbonate and vanadium pentoxide in a molar ratio of 2.00:1.00:0.50;Rare earth oxide a is holmium oxide, and rare earth oxide b is ytterbium oxide.

[0077] Dielectric layer B includes the following raw materials by weight: 100 parts of barium titanate matrix B, 5.357 parts of liquid modified dopant B;Wherein, liquid modified dopant B is composed of magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate, zirconium dioxide in a weight ratio of 0.83:0.043:0.025:1.237:2.223:0.497:0.128:0.374;Specifically, rare earth oxide c is dysprosium oxide, and rare earth oxide d is yttrium oxide.

[0078] A preparation process of a combined medium high-voltage multilayer porcelain dielectric capacitor, comprising the following steps:

[0079] Step one, synthesis of SLV material: silica, lithium carbonate and vanadium pentoxide are added to the sand mill in the ratio, and are sand ground for 5h with pure water as medium, and are dried and crushed, then are calcined at 600 DEG C, and are ground in the sand mill with pure water as medium to a particle size of less than 300 nm after calcination, and are dried and crushed to obtain SLV material;

[0080] Step two, preparation of liquid modified dopant A: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and SLV material prepared in step one are added to the sand mill in the ratio, and are ground to a particle size of less than 300 nm with alcohol as medium to obtain liquid modified dopant A;

[0081] Step three, preparation of the casting slurry A: add dispersant, liquid modified dopant A in ethanol, toluene solvent, then add barium titanate matrix A, grind for 1.5h; then add dioctyl phthalate, polyvinyl butyral resin, stir for 2h, ball mill for 3h, then filter, vacuum defoaming, to obtain the casting slurry A;

[0082] Step four, preparation of liquid modified dopant B: add magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate, zirconium dioxide in a sand mill according to the ratio, and grind to a particle size of less than 300nm with alcohol as the medium to obtain the liquid modified dopant B;

[0083] Step five, preparation of the casting slurry B: add dispersant, liquid modified dopant B in ethanol, toluene solvent, then add barium titanate matrix B, grind for 1.5h; then add dioctyl phthalate, polyvinyl butyral resin, stir for 2h, ball mill for 3h, then filter, vacuum defoaming, to obtain the casting slurry B;

[0084] Step six, green body manufacturing: cast the casting slurry A into the medium layer A with a casting thickness of 50μm; cast the casting slurry B into the medium layer B with a casting thickness of 5μm; then print the nickel electrode slurry onto the medium layer B to form the dielectric layer B, and stack them in the order of dielectric layer B, medium layer A, medium layer B to form the BAB structure, and then go through the water pressure, slicing to manufacture the green body;

[0085] Step seven, the green body manufactured in step four goes through the steps of debinding, sintering, chamfering, end copper, and affixing in sequence to obtain the combined dielectric high-voltage multilayer ceramic capacitor.

[0086] Comparative example 1

[0087] A combined dielectric high-voltage multilayer ceramic capacitor is manufactured by stacking a plurality of combined dielectric layers, wherein the combined dielectric layer is stacked in the order of dielectric layer B, medium layer A, and dielectric layer B to form a BAB structure, specifically, the dielectric layer B comprises the medium layer B and the electrode printed on the medium layer B; further, the thickness of the medium layer A is 50μm, and the thickness of the medium layer B is 5μm.

[0088] The medium layer A comprises the following raw materials in parts by weight: 100 parts of barium titanate base A, 4.649 parts of liquid modified dopant A; wherein the liquid modified dopant A is composed of magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and SLV material in a ratio of 0.202:0.093:1.249:1.842:0.357:0.204:0.702 by weight; specifically, the SLV material is synthesized from silicon dioxide, lithium carbonate and vanadium pentoxide in a molar ratio of 2.00:1.00:0.50; the rare earth oxide a is holmium oxide, and the rare earth oxide b is ytterbium oxide.

[0089] The medium layer B comprises the following raw materials in parts by weight: 100 parts of barium titanate base B, 4.729 parts of liquid modified dopant B; wherein the liquid modified dopant B is composed of magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate and zirconium dioxide in a ratio of 0.202:0.043:0.025:1.237:2.223:0.497:0.128:0.374 by weight; specifically, the rare earth oxide c is dysprosium oxide, and the rare earth oxide d is yttrium oxide.

[0090] A preparation process of a combined medium high-voltage multilayer ceramic dielectric capacitor, comprising the following steps:

[0091] Step one, synthesis of SLV material: silica, lithium carbonate and vanadium pentoxide are added to a sand mill in a predetermined ratio, and are sand milled for 5 hours with pure water as the medium; after drying and crushing, calcination is performed at 600 DEG C; after calcination, grinding is performed in a sand mill with pure water as the medium to obtain a particle size of less than 300 nm; after drying and crushing, the SLV material is obtained;

[0092] Step two, preparation of liquid modified dopant A: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and the SLV material prepared in step one are added to a sand mill in a predetermined ratio, and are ground in alcohol as the medium to obtain a particle size of less than 300 nm, thereby obtaining the liquid modified dopant A;

[0093] Step three, preparation of casting slurry A: a dispersing agent and the liquid modified dopant A are added to ethanol and toluene solvents, followed by adding barium titanate base A, and grinding for 1.5 hours; then dioctyl phthalate and polyvinyl butyral resin are added, and stirring and ball milling are performed for 2 hours and 3 hours respectively; after filtration and vacuum defoaming, the casting slurry A is obtained;

[0094] Step four, preparation of liquid modified dopant B: magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate and zirconium dioxide are added to a sand mill in a predetermined ratio, and are ground in alcohol as the medium to obtain a particle size of less than 300 nm, thereby obtaining the liquid modified dopant B.

[0095] Step five, preparation of the casting slurry B: adding dispersant, liquid modified dopant B in ethanol, toluene solvent, then adding barium titanate matrix B, grinding for 1.5h; adding dioctyl phthalate, polyvinyl butyral resin, stirring for 2h, ball milling for 3h, then filtering, vacuum defoaming, obtaining the casting slurry B;

[0096] Step six, green body manufacturing: casting the casting slurry A into the medium layer A, the casting thickness is 50μm; casting the casting slurry B into the medium layer B, the casting thickness is 5μm; then printing the nickel electrode slurry onto the medium layer B to form the dielectric layer B, and stacking them in the order of dielectric layer B, medium layer A, medium layer B to form the BAB structure, then water pressure, slicing, manufacturing the green body;

[0097] Step seven, the green body manufactured in step four is sequentially subjected to the processes of debinding, sintering, chamfering, end copper, and affixing to obtain the combined dielectric high-voltage multilayer ceramic capacitor.

[0098] Comparative Example 2

[0099] A combined dielectric high-voltage multilayer ceramic capacitor is manufactured by stacking a plurality of combined dielectric layers, wherein the combined dielectric layer is stacked in the order of dielectric layer B, medium layer A, and dielectric layer B to form a BAB structure, specifically, the dielectric layer B comprises the medium layer B and the electrode printed on the medium layer B; further, the thickness of the medium layer A is 50μm, and the thickness of the medium layer B is 5μm.

[0100] The medium layer A comprises the following raw materials by weight: 100 parts of barium titanate matrix A and 5.386 parts of liquid modified dopant A; wherein the liquid modified dopant A is composed of magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide, and SLV material in a weight ratio of 1.039:0.093:1.249:1.842:0.357:0.104:0.702; specifically, the SLV material is synthesized from silicon dioxide, lithium carbonate, and vanadium pentoxide in a molar ratio of 2.00:1.00:0.50; the rare earth oxide a is holmium oxide, and the rare earth oxide b is ytterbium oxide.

[0101] The medium layer B comprises the following raw materials by weight: 100 parts of barium titanate matrix B and 4.609 parts of liquid modified dopant B; wherein the liquid modified dopant B is composed of magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate, and zirconium dioxide in a weight ratio of 0.975:0.043:0.025:1.237:2.223:0.497:0.128:0.374; specifically, the rare earth oxide c is dysprosium oxide, and the rare earth oxide d is yttrium oxide.

[0102] A preparation process of a combined dielectric high-voltage multilayer ceramic capacitor, comprising the following steps:

[0103] Step one, synthesis of SLV material: silica, lithium carbonate, vanadium pentoxide are added into a sand mill according to the ratio, and are sand milled for 5h with pure water as the medium, and are dried and crushed, and then are calcined at 600 DEG C, and then are ground in the sand mill with pure water as the medium to a particle size of less than 300nm, and then are dried and crushed to obtain the SLV material;

[0104] Step two, preparation of liquid modified dopant A: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and the SLV material prepared in step one are added into a sand mill according to the ratio, and are ground to a particle size of less than 300nm with alcohol as the medium to obtain the liquid modified dopant A;

[0105] Step three, preparation of flow casting slurry A: a dispersing agent, the liquid modified dopant A, and then barium titanate matrix A are added into ethanol and toluene solvents, and are ground for 1.5h; dioctyl phthalate and polyvinyl butyral resin are added and stirred for 2h, and are ball milled for 3h, and then are filtered, vacuumized and defoamed to obtain the flow casting slurry A;

[0106] Step four, preparation of liquid modified dopant B: magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silica, calcium carbonate and zirconium dioxide are added into a sand mill according to the ratio, and are ground to a particle size of less than 300nm with alcohol as the medium to obtain the liquid modified dopant B;

[0107] Step five, preparation of flow casting slurry B: a dispersing agent and the liquid modified dopant B are added into ethanol and toluene solvents, and then barium titanate matrix B is added and ground for 1.5h; dioctyl phthalate and polyvinyl butyral resin are added and stirred for 2h, and are ball milled for 3h, and then are filtered, vacuumized and defoamed to obtain the flow casting slurry B;

[0108] Step six, green body manufacturing: the flow casting slurry A is flow cast into a dielectric layer A with a flow casting thickness of 50μm; the flow casting slurry B is flow cast into a dielectric layer B with a flow casting thickness of 5μm; then a nickel electrode slurry is printed onto the dielectric layer B to form a dielectric layer B, and the dielectric layer B, the dielectric layer A and the dielectric layer B are stacked in sequence to form a BAB structure, and then are subjected to water pressure and slicing to manufacture a green body;

[0109] Step seven, the green body manufactured in step four is sequentially subjected to the processes of debinding, sintering, chamfering, end coppering and sintering to obtain the combined dielectric high-voltage multilayer ceramic capacitor.

[0110] Comparative example 3

[0111] The application discloses a combined dielectric high-voltage multilayer porcelain dielectric capacitor, which is prepared by stacking a plurality of combined dielectric layers.

[0112] The medium layer A comprises the following raw materials in parts by weight: 100 parts of barium titanate matrix A, and 3.947 parts of liquid modified dopant A; wherein the liquid modified dopant A is composed of magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate and zirconium dioxide in a proportion of 0.202:0.093:1.249:1.842:0.357:0.204 by weight; specifically, the rare earth oxide a is holmium oxide, and the rare earth oxide b is ytterbium oxide.

[0113] The medium layer B comprises the following raw materials in parts by weight: 100 parts of barium titanate matrix B, and 5.502 parts of liquid modified dopant B; wherein the liquid modified dopant B is composed of magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate and zirconium dioxide in a proportion of 0.975:0.043:0.025:1.237:2.223:0.497:0.128:0.374 by weight; specifically, the rare earth oxide c is dysprosium oxide, and the rare earth oxide d is yttrium oxide.

[0114] A preparation process of the combined dielectric high-voltage multilayer porcelain dielectric capacitor, comprising the following steps.

[0115] Step one, preparing the liquid modified dopant A: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate and zirconium dioxide are added into a sand mill in a proportion, and are ground into a particle size of less than 300 nm with alcohol as a medium to obtain the liquid modified dopant A;

[0116] Step two, preparing the casting slurry A: a dispersing agent and the liquid modified dopant A are added into ethanol and toluene solvents, and then the barium titanate matrix A is added and ground for 1.5 hours; dioctyl phthalate and polyvinyl butyral resin are added and stirred for 2 hours, and then ball milling is conducted for 3 hours; the casting slurry A is obtained after filtration, vacuumizing and defoaming.

[0117] Step three, preparing the liquid modified dopant B: magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate and zirconium dioxide are added into a sand mill in a proportion, and are ground into a particle size of less than 300 nm with alcohol as a medium to obtain the liquid modified dopant B.

[0118] Step four, preparation of the casting slurry B: add dispersant, liquid modified dopant B in ethanol, toluene solvent, then add barium titanate matrix B, grind for 1.5h; add dioctyl phthalate, polyvinyl butyral resin, stir for 2h, ball mill for 3h, then filter, vacuum defoaming, obtain casting slurry B;

[0119] Step five, green body manufacturing: cast the casting slurry A into the medium layer A, the casting thickness is 50μm; cast the casting slurry B into the medium layer B, the casting thickness is 5μm; then print the nickel electrode slurry onto the medium layer B to form the dielectric layer B, and stack them in the order of dielectric layer B, medium layer A, medium layer B to form the BAB structure, then go through water pressure, slicing, to manufacture the green body;

[0120] Step six, the green body manufactured in step four goes through the processes of degreasing, sintering, chamfering, end copper, and affixing in sequence to obtain the combined dielectric high-voltage multilayer ceramic capacitor.

[0121] Comparative example 4

[0122] A combined dielectric high-voltage multilayer ceramic capacitor is manufactured by stacking a plurality of combined dielectric layers, wherein the combined dielectric layer is stacked in the order of dielectric layer B, medium layer A, dielectric layer B to form a BAB structure, specifically, the dielectric layer B comprises the medium layer B and the electrode printed on the medium layer B; further, the thickness of the medium layer A is 50μm, and the thickness of the medium layer B is 5μm.

[0123] The medium layer A comprises the following raw materials by weight: 100 parts of barium titanate matrix A, 4.293 parts of liquid modified dopant A; wherein the liquid modified dopant A is composed of magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide, SLV material in a weight ratio of 0.202:0.093:1.249:1.842:0.102:0.103:0.702; specifically, the SLV material is synthesized from silicon dioxide, lithium carbonate, vanadium pentoxide in a molar ratio of 2.00:1.00:0.50; the rare earth oxide a is holmium oxide, and the rare earth oxide b is ytterbium oxide.

[0124] The medium layer B comprises the following raw materials by weight: 100 parts of barium titanate matrix B, 5.502 parts of liquid modified dopant B; wherein the liquid modified dopant B is composed of magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate, zirconium dioxide in a weight ratio of 0.975:0.043:0.025:1.237:2.223:0.497:0.128:0.374; specifically, the rare earth oxide c is dysprosium oxide, and the rare earth oxide d is yttrium oxide.

[0125] A preparation process of a combined dielectric high-voltage multilayer ceramic capacitor, comprising the following steps:

[0126] Step one, synthesis of SLV material: silica, lithium carbonate, vanadium pentoxide are added into a sand mill according to the ratio, and are sand milled for 5h with pure water as the medium, and then are dried and crushed, and then are calcined at 600 DEG C, and then are ground in the sand mill with pure water as the medium to a particle size of less than 300nm, and then are dried and crushed to obtain the SLV material;

[0127] Step two, preparation of liquid modified dopant A: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and the SLV material prepared in step one are added into a sand mill according to the ratio, and are ground to a particle size of less than 300nm with alcohol as the medium to obtain the liquid modified dopant A;

[0128] Step three, preparation of flow casting slurry A: a dispersing agent, the liquid modified dopant A, and then barium titanate matrix A are added into ethanol and toluene solvents, and are ground for 1.5h; dioctyl phthalate and polyvinyl butyral resin are added and stirred for 2h, and are ball milled for 3h, and then are filtered, vacuumized and defoamed to obtain the flow casting slurry A;

[0129] Step four, preparation of liquid modified dopant B: magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silica, calcium carbonate and zirconium dioxide are added into a sand mill according to the ratio, and are ground to a particle size of less than 300nm with alcohol as the medium to obtain the liquid modified dopant B;

[0130] Step five, preparation of flow casting slurry B: a dispersing agent and the liquid modified dopant B are added into ethanol and toluene solvents, and then barium titanate matrix B is added and ground for 1.5h; dioctyl phthalate and polyvinyl butyral resin are added and stirred for 2h, and are ball milled for 3h, and then are filtered, vacuumized and defoamed to obtain the flow casting slurry B;

[0131] Step six, green body manufacturing: the flow casting slurry A is flow cast into a dielectric layer A with a flow casting thickness of 50μm; the flow casting slurry B is flow cast into a dielectric layer B with a flow casting thickness of 5μm; then a nickel electrode slurry is printed onto the dielectric layer B to form a dielectric layer B, and the dielectric layer B, the dielectric layer A and the dielectric layer B are stacked in sequence to form a BAB structure, and then are subjected to water pressure and slicing to manufacture a green body;

[0132] Step seven, the green body manufactured in step four is sequentially subjected to the processes of debinding, sintering, chamfering, end coppering and soldering to obtain the combined dielectric high-voltage multilayer ceramic capacitor.

[0133] Comparative example 5

[0134] A kind of combined medium high-voltage multilayer porcelain dielectric capacitor is fired by mutual superposition of multiple combined dielectric layers, wherein, combined dielectric layer is formed by the order of dielectric layer B, dielectric layer A, dielectric layer B inside BAB structure is superimposed, specifically, dielectric layer B includes dielectric layer B and electrode printed on dielectric layer B;Further, the thickness of dielectric layer A is 50um, and the thickness of dielectric layer B is 5um.

[0135] Dielectric layer A includes the following raw materials by weight: 100 parts of barium titanate matrix A, 4.649 parts of liquid modified dopant A;Wherein, liquid modified dopant A is composed of magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide, SLV material in a weight ratio of 0.202:0.093:1.249:1.842:0.357:0.104:0.702;Specifically, SLV material is synthesized by silicon dioxide, lithium carbonate and vanadium pentoxide in a molar ratio of 2.00:1.00:0.50;Rare earth oxide a is holmium oxide, and rare earth oxide b is ytterbium oxide.

[0136] Dielectric layer B includes the following raw materials by weight: 100 parts of barium titanate matrix B, 6.202 parts of liquid modified dopant B;Wherein, liquid modified dopant B is composed of magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate, zirconium dioxide in a weight ratio of 0.975:0.043:0.025:1.737:2.423:0.497:0.128:0.374;Specifically, rare earth oxide c is dysprosium oxide, and rare earth oxide d is yttrium oxide.

[0137] A preparation process of a combined medium high-voltage multilayer porcelain dielectric capacitor, comprising the following steps:

[0138] Step one, synthesis of SLV material: silicon dioxide, lithium carbonate and vanadium pentoxide are added to the sand mill in the ratio, and are sand ground for 5h with pure water as medium, and are dried and crushed, then are calcined at 600 DEG C, and are ground in the sand mill with pure water as medium after calcination to a particle size of less than 300nm, and are dried and crushed to obtain SLV material;

[0139] Step two, preparation of liquid modified dopant A: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and SLV material prepared in step one are added to the sand mill in the ratio, and are ground to a particle size of less than 300nm with alcohol as medium to obtain liquid modified dopant A;

[0140] Step three, preparation of the casting slurry A: adding dispersant, liquid modified dopant A in ethanol, toluene solvent, then adding barium titanate matrix A, grinding for 1.5h; then adding dioctyl phthalate, polyvinyl butyral resin, stirring for 2h, ball milling for 3h, then filtering, vacuum defoaming, obtaining the casting slurry A;

[0141] Step four, preparation of the liquid modified dopant B: adding magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate, zirconium dioxide into sand mill according to the ratio, and grinding to particle size less than 300nm with alcohol as medium, obtaining the liquid modified dopant B;

[0142] Step five, preparation of the casting slurry B: adding dispersant, liquid modified dopant B in ethanol, toluene solvent, then adding barium titanate matrix B, grinding for 1.5h; then adding dioctyl phthalate, polyvinyl butyral resin, stirring for 2h, ball milling for 3h, then filtering, vacuum defoaming, obtaining the casting slurry B;

[0143] Step six, green body manufacturing: casting the casting slurry A into the medium layer A, the casting thickness is 50μm; casting the casting slurry B into the medium layer B, the casting thickness is 5μm; then printing the nickel electrode slurry onto the medium layer B to form the dielectric layer B, and stacking them in the order of dielectric layer B, medium layer A, dielectric layer B, forming the BAB structure, then water pressure, slicing, manufacturing the green body;

[0144] Step seven, the green body manufactured in step four is sequentially subjected to the processes of debinding, sintering, chamfering, end copper, and affixing, obtaining the combined dielectric high-voltage multilayer ceramic capacitor.

[0145] Comparative example 6

[0146] A combined dielectric high-voltage multilayer ceramic capacitor is manufactured by stacking a plurality of combined dielectric layers, wherein the combined dielectric layers are stacked in the order of dielectric layer B, medium layer A, dielectric layer B to form a BAB structure, specifically, the dielectric layer B comprises the medium layer B and the electrode printed on the medium layer B; further, the thickness of the medium layer A is 50um, and the thickness of the medium layer B is 5um.

[0147] The medium layer A comprises the following raw materials by weight: 100 parts of barium titanate matrix A, 4.699 parts of liquid modified dopant A; wherein the liquid modified dopant A is composed of magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide, silicon dioxide, lithium carbonate, vanadium pentoxide in a weight ratio of 0.252:0.093:1.249:1.842:0.357:0.104:0.296:0.182:0.224; specifically, the rare earth oxide a is holmium oxide, and the rare earth oxide b is ytterbium oxide.

[0148] The medium layer B comprises the following raw materials in parts by weight: 100 parts of barium titanate matrix B, 5.502 parts of liquid modified dopant B; wherein the liquid modified dopant B is composed of magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate, zirconium dioxide in a ratio of 0.975:0.043:0.025:1.237:2.223:0.497:0.128:0.374 by weight; specifically, the rare earth oxide c is dysprosium oxide, and the rare earth oxide d is yttrium oxide.

[0149] A preparation process of a combined medium high-voltage multilayer ceramic dielectric capacitor, comprising the following steps:

[0150] Step one, grinding of liquid modified dopant A: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide, silicon dioxide, lithium carbonate, vanadium pentoxide are added into a sand mill in a proportion, and are ground in alcohol as a medium to a particle size of less than 300 nm to obtain liquid modified dopant A;

[0151] Step two, preparation of casting slurry A: a dispersing agent and liquid modified dopant A are added into ethanol and toluene solvents, and then barium titanate matrix A is added and ground for 1.5 hours; dioctyl phthalate and polyvinyl butyral resin are added and stirred for 2 hours, and ball milled for 3 hours; then filtration, vacuum degassing are performed to obtain casting slurry A;

[0152] Step three, preparation of liquid modified dopant B: magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate, zirconium dioxide are added into a sand mill in a proportion, and are ground in alcohol as a medium to a particle size of less than 300 nm to obtain liquid modified dopant B;

[0153] Step four, preparation of casting slurry B: a dispersing agent and liquid modified dopant B are added into ethanol and toluene solvents, and then barium titanate matrix B is added and ground for 1.5 hours; dioctyl phthalate and polyvinyl butyral resin are added and stirred for 2 hours, and ball milled for 3 hours; then filtration, vacuum degassing are performed to obtain casting slurry B;

[0154] Step five, green body manufacturing: casting slurry A is cast into medium layer A with a casting thickness of 50 microns; casting slurry B is cast into medium layer B with a casting thickness of 5 microns; then nickel electrode slurry is printed onto the medium layer B to form a dielectric layer B, and the dielectric layer B, the medium layer A, and the medium layer B are stacked in sequence to form a BAB structure, and then water pressure and slicing are performed to manufacture a green body;

[0155] Step six, the green body manufactured in step four is sequentially subjected to the processes of degreasing, sintering, chamfering, end coppering, and burn-on to obtain the combined dielectric high-voltage multilayer ceramic capacitor.

[0156] The cast slurry A and the cast slurry B in Examples 1-3 and Comparative Examples 1-6 were respectively cast into dielectric layers to prepare capacitors, which were tested to obtain the following data, and the results are shown in the following table:

[0157] Table 1: Performance test results of each capacitor of dielectric A

[0158]

[0159] Table 2: Performance test results of each capacitor of dielectric B

[0160]

[0161]

[0162] The capacitors prepared in Examples 1-3 and Comparative Examples 1-6 were tested to obtain the following data, and the results are shown in the following table:

[0163] Table 3: Comprehensive performance test results of each capacitor

[0164]

[0165] As shown in the above tables, the combined dielectric high-voltage multilayer ceramic capacitor prepared in the present application has high dielectric constant, smooth dielectric temperature characteristic curve, low loss, high insulation resistance, high voltage resistance, and other excellent properties by combining different dielectric layers and modifying and doping barium titanate with magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide a, rare earth oxide b, rare earth oxide c, rare earth oxide d, barium carbonate, calcium carbonate, zirconium dioxide, and SLV material.

[0166] As shown by the comparison between Examples 1-3 and Comparative Examples 1-2, the addition of excess magnesium element in dielectric B in Examples 1-3 can improve the insulation resistance and voltage resistance of the combined dielectric as a whole and reduce the dielectric loss; the addition of magnesium element within a limited range in dielectric A can make the combined dielectric have a smooth dielectric temperature characteristic curve.

[0167] As shown by the comparison between Examples 1-3 and Comparative Examples 2-3, the addition of zirconium and barium elements within a limited range in dielectric A in Examples 1-3 can make the combined dielectric have a smooth dielectric temperature characteristic curve (meeting the X7R requirement).

[0168] By comparing examples 1-3 with comparative examples 3 and 6, it can be seen that the addition of medium A and SLV material in examples 1-3 makes the combined medium have high dielectric constant (≥4500) and smooth dielectric temperature characteristic curve (complying with X7R requirement); this is because the small amount of liquid phase generated by the calcined SLV material during sintering helps the system to sinter, which can improve the density and thus improve the dielectric constant of the medium; at the same time, the addition of silicon element in the SLV material can play the role of smoothing the dielectric temperature characteristic curve.

[0169] By comparing examples 1-3 with comparative example 5, it can be seen that the medium B in comparative example 5 adds more dysprosium oxide and yttrium oxide than examples 1-3, so the insulation resistance of the combined medium decreases.

[0170] By comparing examples 1 with comparative examples 1-6, it can be seen that by combining different medium layers, the excellent performance of different medium layers can be effectively combined, and results that are difficult to obtain by doping modification of a single medium layer can be obtained, and the prepared capacitor has high dielectric constant (≥4500), smooth dielectric temperature characteristic curve (complying with X7R requirement), low loss (≤3.0%), high insulation resistance (RC@25℃≥5000MΩ·μF), high withstand voltage (>150V / μm) and other excellent performances.

[0171] The above is only a preferred embodiment of the present application, and therefore cannot limit the scope of the present application, that is, equivalent changes and modifications made according to the scope of the present application and the content of the specification should still be within the scope of the present application.

Claims

1. A combined dielectric high-voltage multilayer ceramic capacitor characterized by: The dielectric layers are stacked by firing a plurality of combined dielectric layers, the combined dielectric layers are stacked in the order of dielectric layer B, dielectric layer A and dielectric layer B to form a BAB structure, the dielectric layer B comprises a dielectric layer B and an electrode printed on the dielectric layer B; The dielectric layer A comprises the following raw materials by weight: 100 parts of barium titanate matrix A, 1.409-6.315 parts of liquid modified dopant A; The liquid modified dopant A is composed of magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and SLV material in a weight ratio of 0.086-0.259:0.069-0.128:0.320-1.620:0.484-2.535:0.085-0.423:0.158-0.317:0.13-1.

34. The SLV material is synthesized from silicon dioxide, lithium carbonate and vanadium pentoxide in a molar ratio of 2.00:1.00:0.

50.

2. A multilayer ceramic dielectric capacitor of claim 1, wherein: The rare earth oxide a is one or both of dysprosium oxide and holmium oxide, and the rare earth oxide b is one or both of yttrium oxide and ytterbium oxide.

3. A multilayer ceramic dielectric capacitor of claim 1, wherein: the dielectric layer is formed of a dielectric material having a dielectric constant of 100 or more. The dielectric layer B comprises the following raw materials by weight: 100 parts of barium titanate matrix B, 1.615-6.597 parts of liquid modified dopant B.

4. A multilayer ceramic dielectric capacitor of claim 3, wherein: The liquid modified dopant B is composed of magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate and zirconium dioxide in a weight ratio of 0.518-1.037:0.029-0.069:0.008-0.078:0.320-1.620:0.484-2.535:0.129-0.515:0.021-0.215:0.106-0.

528.

5. A multilayer ceramic dielectric capacitor of claim 4, wherein: The rare earth oxide c is one or both of dysprosium oxide and holmium oxide, and the rare earth oxide d is one or both of yttrium oxide and ytterbium oxide.

6. A multilayer ceramic dielectric capacitor of claim 3, wherein: The particle size of the barium titanate matrix A is 300-800 nm, and the particle size of the barium titanate matrix B is 100-300 nm.

7. A multilayer ceramic dielectric capacitor of claim 1, wherein: the dielectric layer is formed of a dielectric material having a dielectric constant of 100 or more. The thickness of the dielectric layer A is 50 um, and the thickness of the dielectric layer B is 5 um.

8. The process for making a multilayer ceramic dielectric capacitor of claim 1, wherein: The method comprises the following steps: Step one: synthesizing SLV material: silica, lithium carbonate and vanadium pentoxide are added to a sand mill in a predetermined ratio, and are ground in pure water as a medium for 2-8 hours, then are dried, crushed, calcined at 500-700°C, ground in a sand mill with pure water as a medium to a particle size of less than 300 nm, and then are dried and crushed to obtain the SLV material; Step two: preparing liquid modified dopant A: magnesium oxide, trimanganese tetroxide, rare earth oxide a, rare earth oxide b, barium carbonate, zirconium dioxide and the SLV material prepared in step one are added to a sand mill in a predetermined ratio, and are ground in alcohol as a medium to a particle size of less than 300 nm to obtain the liquid modified dopant A; Step three, preparation of the casting slurry A: adding dispersant, liquid modified dopant A in ethanol, toluene solvent, then adding barium titanate matrix A, grinding for 1.5h; adding dioctyl phthalate, polyvinyl butyral resin, stirring for 2h, ball milling for 3h, then filtering, vacuum defoaming, obtaining the casting slurry A; Step four, preparation of the liquid modified dopant B; Step five, preparation of the casting slurry B; Step six, green body manufacturing: casting the casting slurry A into the medium layer A, the casting thickness is 50μm; casting the casting slurry B into the medium layer B, the casting thickness is 5μm; then printing the nickel electrode slurry onto the medium layer B to form the dielectric layer B, and stacking them in the order of dielectric layer B, medium layer A, medium layer B to form the BAB structure, then water pressure, slicing, obtaining the green body; Step seven, the green body manufactured in step four is sequentially subjected to the processes of degreasing, sintering, chamfering, end copper, and burn-on, obtaining the combined medium high-voltage multilayer ceramic capacitor.

9. The process for making a multilayer ceramic dielectric capacitor of claim 8, wherein: Step four, the specific operation of preparing the liquid modified dopant B is as follows: adding magnesium oxide, trimanganese tetroxide, vanadium pentoxide, rare earth oxide c, rare earth oxide d, silicon dioxide, calcium carbonate, and zirconium dioxide into a sand mill according to the ratio, and grinding to a particle size of less than 300nm with alcohol as the medium, obtaining the liquid modified dopant B.

10. The process for making a multilayer ceramic dielectric capacitor of claim 8, wherein: Step five, the specific operation of preparing the casting slurry B is as follows: adding dispersant, liquid modified dopant B in ethanol, toluene solvent, then adding barium titanate matrix B, grinding for 1.5h; adding dioctyl phthalate, polyvinyl butyral resin, stirring for 2h, ball milling for 3h, then filtering, vacuum defoaming, obtaining the casting slurry B. Step five, the specific operation of preparing the casting slurry B is as follows: adding dispersant, liquid modified dopant B in ethanol, toluene solvent, then adding barium titanate matrix B, grinding for 1.5h; adding dioctyl phthalate, polyvinyl butyral resin, stirring for 2h, ball milling for 3h, then filtering, vacuum defoaming, obtaining the casting slurry B.

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