CN1728303A - Multilayer ceramic capacitor and manufacturing method thereof - Google Patents

Abstract

The present invention provides a laminated ceramic capacitor and a manufacturing method thereof. The laminated ceramic capacitor is composed of alternately laminated dielectric layers and internal electrode layers. The relationship between barium titanate particles (BMTL) containing alkaline earth metal components other than Ba and barium titanate particles (BMTH) containing alkaline earth metal components other than Ba at a ratio of 0.4 atomic % or more by area ratio BMTL/BMTH = 0.1 to 9 By coexistence, even if the dielectric layer is thinned, reliability such as capacitance-temperature characteristics and high-temperature load life is excellent.

Description

Multilayer ceramic capacitor and manufacturing method thereof

technical field

The present invention relates to a multilayer ceramic capacitor and its manufacturing method. In particular, it relates to the capacitance temperature characteristics and high temperature characteristics of alternately laminating very thin dielectric layers and internal electrode layers, which are used in high-performance electronic equipment such as computers and mobile phones. A small-sized high-capacity multilayer ceramic capacitor excellent in reliability such as load life and a method for manufacturing the same.

Background technique

In recent years, with the miniaturization and high performance of electronic equipment, the multilayer ceramic capacitors used in them are also required to be small and high-capacity. Therefore, the number of stacked layers of dielectric layers and internal electrode layers is increased, and the thickness of the dielectric layer body is reduced. In addition, even as characteristics of multilayer ceramic capacitors, improvements in reliability such as capacitance temperature characteristics and high-temperature load life are sought.

Furthermore, as such a multilayer ceramic capacitor, for example, a multilayer ceramic capacitor disclosed in the following patent documents is known.

First, in JP-A-2001-230149, a laminated ceramic capacitor is disclosed, in which BaTiO ₃ and MgO are fired in advance, and then various oxides of rare earth elements or acceptor-type elements are added to the fired powder to prepare Dielectric ceramics. By adopting such a two-stage mixing method, even after sintering, MgO, which is solid-dissolved first, suppresses the diffusion of various oxides of rare earth elements or acceptor-type elements added later into the BaTiO ₃ crystal particles, resulting in The desired properties described above are obtained.

Japanese Unexamined Patent Publication No. 9-241075 discloses a laminated ceramic capacitor in which dielectric ceramics are composed of two or more types of crystal particles having an average particle size of 0.1 to 0.3 μm and different capacitance temperature characteristics. Thereby, a multilayer ceramic capacitor having flat capacitance temperature characteristics and excellent DC bias characteristics can be obtained.

According to this publication, in dielectric particles mainly composed of BaTiO ₃ , if the particle size is 1 μm or less, it is difficult to form a structure commonly called a core shell that can realize flat capacitance-temperature characteristics or excellent DC bias characteristics. of crystal particles. Therefore, with respect to the dielectric particles having a particle size of 1 μm or less, by making them finer, dielectric activity is suppressed, and flat capacitance-temperature characteristics or excellent DC bias characteristics are obtained as a whole of the dielectric ceramic.

It is described in JP-A-2000-58378 that by setting Ba _1-X Ca _X TiO ₃ in which part of Ba of BaTiO ₃ constituting the dielectric ceramic is substituted with Ca, flat capacitance temperature characteristics and excellent DC bias can be obtained. characteristic.

However, in the multilayer ceramic capacitor disclosed in JP-A-2001-230149, since the pre-mixing and firing of BaTiO ₃ and MgO are used, the dielectric constant of the dielectric ceramic can be improved, and even in terms of capacitance temperature characteristics , and can better meet the B characteristics (temperature range: -25°C to 85°C, capacitance change rate within ±10%), but at present, in terms of capacitance temperature characteristics, it cannot meet the X7R with a wide temperature range (temperature range: -55°C ~125°C, capacitance change rate within ±15%).

Next, in the dielectric ceramics described in JP-A-9-241075, the dielectric constant can only be increased to about 2100 at best due to the micronization of the dielectric particles.

In Ba _1-X Ca _X TiO ₃ described in JP-A-2000-58378, the dielectric constant is greatly reduced by Ca substitution, and it is difficult to make the dielectric constant higher than 2,000.

In particular, in capacitors having the dielectric layers described in the above-mentioned patent documents, the dielectric constant is low in the AC electric field range of 0.002 to 1 Vrms/μm.

Contents of the invention

The main object of the present invention is to provide a small-sized, high-capacity multilayer ceramic capacitor and a manufacturing method thereof that are excellent in reliability such as capacitance temperature characteristics and high-temperature load life even when the thickness of the dielectric layer is reduced.

Another object of the present invention is to provide a small-sized capacitor with a high dielectric constant in the AC electric field range of 0.002 to 1 Vrms/μm and excellent reliability such as capacitance-temperature characteristics and high-temperature load life even if the dielectric layer is thinned. High-capacity multilayer ceramic capacitor and its manufacturing method.

The multilayer ceramic capacitor of the present invention is composed of alternately laminated dielectric layers and internal electrode layers. Barium titanate particles (BMTL) containing alkaline earth metal components other than Ba in a ratio of 0.2 atomic % or less and 0.4 atomic % or more coexist on the dielectric layer at an area ratio of BMTL/BMTH = 0.1 to 9. Barium titanate particles (BMTH) containing alkaline earth metal components other than Ba.

That is, according to the present invention, by coexisting two or more barium titanate particles having different concentrations of alkaline earth metal components other than Ba, it is possible to exhibit a high dielectric constant based on dielectric particles having a low concentration of alkaline earth metal components other than Ba. The temperature characteristic of the dielectric constant can be flattened by the dielectric particles having a high concentration of alkaline earth metal components other than Ba.

The dielectric layer preferably satisfies the relationship of DL≦DH when the average particle size of BMTL is defined as DL and the average particle size of BMTH is defined as DH.

That is, by compositing these dielectric particles in a state having a particle size relationship of DL≦DH, the dielectric constant can be increased, and the temperature characteristic of the dielectric constant can be further flattened. In this case, the alkaline earth metal component is preferably at least one selected from Mg, Ca, and Sr from the viewpoint of maintaining a high dielectric constant and flattening the temperature characteristics of the dielectric constant.

In addition, according to the present invention, for thinning and high insulation of the dielectric layer, it is preferable that the average particle diameters of BMTL and BMTH are both 0.5 μm or less. In addition, the thickness of the dielectric layer is preferably 4 μm or less from the viewpoint of enabling miniaturization even with high multilayer for high capacitance of the capacitor. Furthermore, from the viewpoint of reducing the material cost of the internal electrodes even with a high multilayer structure, it is preferable that the internal electrode layers contain a base metal as a main component.

In the multilayer ceramic capacitor of the present invention, when DL is the average particle diameter of BMTL and DH is the average particle diameter of BMTH, DL>DH may be satisfied, and DL/DH=1.1-2 is preferable. Furthermore, BMTH preferably contains an alkaline earth metal component other than Ba in a ratio of 0.5 to 2.5 at%.

That is, by pressing DL>DH, preferably DL/DH=1.1～2, these barium titanate particles are composited, and the dielectric constant is high in the range of alternating electric field strength of 0.002～1Vrms/μm, and the temperature characteristic of the dielectric constant can be more flattened. Furthermore, since the dielectric particles having a low concentration of the alkaline earth metal component and the dielectric particles having a high concentration of the alkaline earth metal component coexist, the dielectric layer can be highly insulated.

In this case, the alkaline earth metal component is preferably at least one selected from Mg, Ca, and Sr, from the viewpoint of maintaining a high dielectric constant and flattening the temperature characteristic of the dielectric constant. In addition, by setting the average particle diameters of both BMTL and BMTH to be 0.7 μm or less, it is possible to increase the grain boundaries in the dielectric layer and improve the insulation of the entire dielectric layer. In addition, it is preferable that both BMTL and BMTH contain rare earth elements, and that the concentration gradient thereof is 0.05 atomic %/nm or more from the surface to the inside with the particle surface as the highest concentration. For thinning, high capacitance, and high insulation of the dielectric layer, the thickness of the dielectric layer is preferably 4 μm or less. Furthermore, from the viewpoint of reducing the material cost of the internal electrodes even with a high-layer stack, it is preferable that the internal electrode layers contain a base metal as a main component.

The multilayer ceramic capacitor of the present invention described above can be produced by the following production method. That is, the manufacturing method of the multilayer ceramic capacitor of the present invention includes the following steps:

(a) adding oxides of alkaline earth metal elements other than Ba to _BaTiO3 powder, and roasting at a temperature below 850°C to prepare _BaTiO3 roasted powder;

(b) BaTiO ₃ calcined powder, Ba _1-X M _X TiO ₃ (M: Mg, Ca or Sr, X=0.01～0.2) powder, rare earth element compound, Mn compound, alkaline earth metal element other than Ba The oxide and organic vehicle are mixed, the slurry is prepared, and then shaped to form a dielectric green sheet;

(c) a step of forming an internal electrode pattern on the surface of the dielectric green sheet;

(d) A step of laminating and firing the dielectric green sheets on which the internal electrode patterns are formed.

That is, according to the production method of the present invention, BaTiO ₃ powder and Ba _1-X M _X TiO ₃ (M and X are the same as above.) powder having different sinterability and grain growth rate are used as raw material powders for forming dielectric ceramics. . In addition, during firing, in order to suppress the reaction between these raw material powders, an alkaline earth metal element other than Ba is added to the BaTiO ₃ raw material powder on the side not containing alkaline earth metal elements, and it is fired at a low temperature below 850°C. Part of the alkaline earth metal elements other than Ba is solid-dissolved in the BaTiO ₃ powder. As a result, the alkaline earth metal element is solid-dissolved, especially near the surface layer of the BaTiO ₃ raw material powder. As a result, since it is possible to suppress the diffusion of alkaline earth metal elements from the Ba _1-X M _X TiO ₃ (M and X are the same as above.) powder side to the side of BaTiO ₃ that does not contain alkaline earth metal elements, it is also possible to suppress the interaction between the raw material powders. reaction, the coexistence state of dielectric particles having different concentrations of alkaline earth metal components in the dielectric layer can be maintained.

In addition, according to the method of partially dissolving the alkaline earth metal element in the BaTiO ₃ raw material powder at a low temperature of 850° C. or lower, it is also possible to suppress the solid solution of the rare earth element compound or other additives added later in the BaTiO ₃ powder. In addition, according to this method, the relationship between the average particle diameter DL of BMTL and the average particle diameter DH of BMTH, that is, the relationship of DL≦DH can be easily satisfied in the dielectric layer.

In this case, the ratio of the oxides of the alkaline earth metal elements added in the step (a) is specified as the ratio of the oxides of the total alkaline earth metal elements added in the step (a) and (b) in molar ratio. 30-70%, can improve the effect of adding alkaline earth metal elements. In particular, if the oxide of the alkaline earth metal element to be added is MgO, since there is a large difference in the ionic radius of Ba ions from BaTiO ₃ , the amount of solid solution of ions to BaTiO ₃ can be reduced, and MgO can be solid-dissolved in BaTiO 3 . ₃ near the surface layer.

In addition, if M in Ba _1-X M _X TiO ₃ (M and X are the same as above.) is defined as Ca in the powder, since an element smaller than M such as Mg is solid-dissolved in BaTiO ₃ in advance, it is possible to Diffusion of alkaline earth metal elements having a large ionic radius, such as Ca, which diffuses later, is suppressed. That is, with respect to the effect of adding an alkaline earth metal element other than Ba to the BaTiO powder of the present invention, the more the element with a smaller ionic radius of the alkaline earth metal element added to the BaTiO powder is used, the _{more the} alkaline earth metal element can be suppressed from Ba _1-X M _X TiO ₃ (M and X are the same as above.) Diffusion on the powder side. In addition, when the average particle size of the BaTiO ₃ powder and Ba _1-X M _X TiO ₃ (M and X are the same as above.) powder used in such a production method is 0.4 μm or less in which the solid solution of the refractory element is 0.4 μm or less, More suitable. In addition, the internal electrode pattern in the above manufacturing method is preferably composed of a base metal from the viewpoint of low cost, and a conductive pattern made of a plated film is preferably used from the viewpoint of thinner layers.

Another manufacturing method of the multilayer ceramic capacitor of the present invention includes the following steps:

(a') BaTiO ₃ powder with an average particle size of 0.05-0.5 μm and Ba _1-X M _X TiO ₃ powder with an average particle size smaller than BaTiO ₃ powder (M: Mg, Ca or Sr, X=0.01- In each of 0.2), adding an alkaline earth metal oxide other than Ba, and roasting at a temperature below 850°C, respectively preparing BaTiO ₃ roasted powder and Ba _1-X M _X TiO ₃ roasted powder;

(b') The BaTiO ₃ roasted powder and Ba _1-X M _X TiO ₃ roasted powder are mixed with rare earth element compounds, Mn compounds, alkaline earth metal oxides and organic vehicles to prepare a slurry, and then molded to form Dielectric green sheet process;

(c') A step of forming an internal electrode pattern on the surface of the dielectric green sheet;

(d') A step of laminating and firing the dielectric green sheets on which the internal electrode patterns are formed.

That is, as raw material powders for forming dielectric ceramics, BaTiO ₃ powder and Ba _1-X M _X TiO ₃ powder having different average particle diameters at the stage of initial raw materials and different sinterability and grain growth rate are used. During firing, in order to suppress the reaction between these raw material powders, alkaline earth metal elements other than Ba are partially solid-dissolved in these powders in advance at a low temperature of 850° C. or lower. Thereby, the alkaline-earth metal element is solid-dissolved, especially near the surface layer of the calcined powder. Accordingly, since it is possible to suppress the diffusion of alkaline earth metal elements from the Ba _1-X M _X TiO ₃ powder side containing alkaline earth metal elements to the BaTiO ₃ side with a small amount of alkaline earth metal elements, and to suppress the reaction between the raw material powders, it is possible to The coexistence state of dielectric particles having different concentrations of alkaline earth metal components in the dielectric layer is maintained.

In this case, by adjusting the ratio of the oxides of the alkaline earth metal elements added in the step (a'), 30 to 60% of the total oxides of the alkaline earth metal elements added in the step (a') and (b') are specified. %, can improve the effect of adding alkaline earth metal elements.

Description of drawings

Fig. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor of the present invention.

Detailed ways

<First Embodiment>

The multilayer ceramic capacitor of this embodiment will be described in detail with reference to the schematic cross-sectional view of FIG. 1 . The multilayer ceramic capacitor of the present invention is constituted by forming external electrodes 3 at both ends of a capacitor body 1 . The external electrodes 3 are formed, for example, by sintering Cu or an alloy paste of Cu and Ni.

Capacitor body 1 is formed by alternately laminating dielectric layers 5 and internal electrode layers 7 . The dielectric layer 5 is composed of dielectric particles 11 mainly composed of Ba and Ti having a low concentration of alkaline earth metals other than Ba, dielectric particles 13 mainly composed of Ba and Ti having a high concentration of alkaline earth metals other than Ba, and Grain boundary phase 15 constitutes. The thickness of the dielectric layer 5 is preferably 4 μm or less, and more preferably 3 μm or less from the viewpoint of increasing the capacitance. In addition, the thickness of the dielectric layer 5 is preferably not less than 0.5 μm, and more preferably not less than 1 μm, from the viewpoint of maintaining high insulation properties. In addition, in order to stabilize the variation in capacitance and the temperature characteristic of capacitance, the thickness variation of dielectric layer 5 is preferably within 10%.

The internal electrode layer 7 is preferably made of a base metal such as Ni or Cu because the production cost can be suppressed even when multi-layered, and Ni is more preferably used because it can be fired simultaneously with the dielectric layer. The thickness of the dielectric layer 7 is preferably 2 μm or less on average.

In particular, the dielectric layer 5 is important to (1) contain barium titanate particles (BMTL) containing alkaline earth metal components other than Ba in a ratio of 0.2 atomic % or less, and contain alkaline earth metal components other than Ba in a ratio of 0.4 atomic % or more. Barium titanate particles (BMTH) of an alkaline earth metal component coexist at a ratio of BMTL/BMTH=0.1 to 9 in terms of area ratio. In this case, the alkaline earth metal component of BMTH is preferably in the range of 0.4 to 1 atomic %.

If the alkaline earth metal component concentration of BMTL ions with a low concentration of alkaline earth metal elements other than Ba is 0.2 atomic % or more, the dielectric constant of the particles will decrease, and it will be difficult to combine with BMTH particles with a high concentration of alkaline earth metal elements other than Ba. It is also difficult to control the temperature characteristics.

In the case where the BMTL/BMTH ratio is less than 0.1, since the amount ratio of BMTH is low, the dielectric constant of dielectric layer 5 is low. In addition, in the case where the BMTL/BMTH ratio is greater than 9, the flattening effect of the temperature characteristic of the dielectric constant formed by BMTH is reduced. Furthermore, from the viewpoint of further improving the above-mentioned dielectric constant and temperature characteristics, BMTL/BMTH=0.25-4 is more preferable.

In addition, in the dielectric particles constituting the dielectric layer of the present invention, it is important to satisfy the relationship of DL≦DH when the average particle diameter of BMTL is defined as DL and the average particle diameter of BMTH is defined as DH. In this case, generally, the dielectric constant on the BMTH side showing a low dielectric constant can be increased, and the temperature characteristics can be improved. Preferably, DL/DH=0.4-1.

In addition, the alkaline earth metal component in the present invention which is dissolved in the BMTH particles having a high ratio of alkaline earth metal elements is preferably at least one selected from Mg, Ca, and Sr, especially from the perspective of improving the solid solution rate of BaTiO ₃ , from the perspective of improving the dielectric constant of BaTiO ₃ and its temperature characteristics, Ca is more preferred.

In addition, the average particle size of both BMTL and BMTH is preferably 0.5 μm or less, more preferably 0.4 μm or less for high insulation, and preferably 0.1 μm or more from the viewpoint of increasing the dielectric constant.

In addition, it is preferable that the thickness of the dielectric layer 5 is not more than 4 μm, and the internal electrode layer 7 is, among base metals (Cu, Ni, Co, etc.), especially from the viewpoint that the sintering temperature of the metal is consistent with the sintering temperature of the above-mentioned dielectric material. It's you.

In addition, in the dielectric layer 5 of the present invention, the rare earth element compound preferably has the highest concentration on the grain boundary surface, that is, the grain boundary phase 15, has a concentration gradient from the surface of the boundary grain particles to the inside of the particle, and is at least 0.05 atomic %/nm. That is, as long as the concentration gradient of the rare earth element is such a condition, it is possible to obtain a dielectric layer that can improve the dielectric constant and high-temperature load life, and can also satisfy the X7R standard as a capacitance temperature characteristic.

Here, as the rare earth element in the present invention, at least one of La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, and Sc is preferable.

In addition, the BaTiO ₃ crystalline particles of the present invention, as described above, are solid-dissolved Mg in the surface region by firing, but the concentration gradient of Mg in the surface region of the BaTiO ₃ crystalline particles improves the diffusion and solid-solution of rare earth elements. From the viewpoint of suppression, it is preferably 0.003 atomic %/nm or more, more preferably 0.01 atomic %/nm or more toward the inside of the grain with the grain boundary part as the high concentration side.

(Manufacturing method)

The production method of the present invention has the steps of preparing BaTiO ₃ powder and Ba _1-X M _X TiO ₃ (M: Mg, Ca or Sr, X=0.01-0.2, the same below) powder, and preparing the BaTiO ₃ powder The process of adding an oxide of an alkaline earth metal element other than Ba, and firing at a temperature below 850°C to prepare BaTiO ₃ fired powder. The Ba _1-X M _X TiO ₃ powder used here becomes the above-mentioned BMTH particles after firing, and the composition range X of the M component is more preferably X=0.02 to 0.1 from the viewpoint of improving the capacitance and temperature characteristics. The important thing is: only for the BaTiO ₃ raw material powder and the BaTiO 3 powder in the Ba _1-X M _X TiO ₃ powder, the BaTiO ₃ powder is roasted at a temperature below 850°C, and the oxides of alkaline earth metal elements other than Ba are prepared to form a solid solution. BaTiO ₃ powder on the surface of the BaTiO ₃ powder, preferably, oxides of alkaline earth metal elements other than Ba exist on the surface of the BaTiO ₃ powder.

As the main raw materials used here, BaTiO ₃ powder and Ba _1-X M _X TiO ₃ powder, based on the reasons of narrow particle size distribution and high crystallinity, are preferably powders obtained by hydrothermal synthesis, and the average particle diameter is preferably 0.1 More than μm and less than 0.4μm. In addition, the specific surface area of such a fine powder is preferably 1.7 to 6.6 (m ² /g). That is, in the present invention, based on the reason that BaTiO ₃ powder is formed in solid solution on the surface of oxides of alkaline earth metal elements other than Ba by low-temperature calcination, since a powder with high reactivity is required, it is preferable to have an average particle size of Even the specific surface area is specified within the above range.

In addition, in the production method of the present invention, at least A kind of barium carbonate crystalline particle, when barium or, barium and alkaline earth metal element is used as A side and titanium is used as B side, from the viewpoint of suppressing the particle growth during firing, preferably, in molar ratio, satisfy A/B ≥1.003 relationship.

Regarding the firing temperature in the production method of the present invention, as described above, as an alkaline earth metal component other than Ba, for example, for the reason of suppressing the solid solution of MgO in the BaTiO ₃ powder in which MgO is solid-dissolved on the surface, it is preferably 850° C. or lower, More preferably 750°C or lower. In addition, the firing temperature is preferably 600°C or higher, more preferably 650°C or higher, for the reason that MgO is surely diffused into a solid solution on the surface of the BaTiO ₃ powder. In addition, the average particle size of the MgO powder used here is preferably 0.3 μm or less. In the present invention, by using BaTiO ₃ powder previously baked with MgO in this way, diffusion and solid solution of rare earth elements can be suppressed.

In this regard, for BaTiO ₃ powder, if the calcination temperature for the solid solution of the oxides of alkaline earth metal elements other than Ba represented by MgO is higher than 850°C, since Mg near the grain boundary is easy to diffuse into solid solution, it will promote the solid solution of rare earth elements. Diffusion and solid solution of the compound tend to cause grain growth of barium titanate particles (BMTL) with a low concentration of alkaline earth metal elements, and the temperature characteristics of the capacitance cannot satisfy the required characteristics.

For the above-mentioned treatment of _the present invention, without first solid-dissolving the oxides of alkaline earth metal elements other than Ba in the BaTiO powder, add BaTiO powder or Ba _{1 -X} M _X TiO ₃ powder, rare earth element In the case of additives such as Mn compounds and Mn compounds, it is difficult to form a solid solution of oxides of alkaline earth metal elements other than Ba on the surface layer of BaTiO ₃ . Therefore, the diffusion of the M component etc. from the Ba _1-X M _X TiO ₃ powder increases, and instead of maintaining the original dielectric constant of BaTiO ₃ , it decreases, resulting in a decrease in capacitance.

In the (a) process in this production method, the ratio of the oxides of the alkaline earth metal elements added is, by molar ratio (mass ratio), the total alkaline earth metal elements added in the (a) (b) process. 30 to 70% of the oxide, the alkaline earth metal element is preferably MgO, and the M component in (Ba, M)TiO ₃ is preferably Ca.

In addition, the average particle diameter of BaTiO ₃ powder and Ba _1-X M _X TiO ₃ powder is preferably 0.4 μm or less. In addition, the dielectric layer of the present invention contains a glass phase, and Si-Li-Ca-based glass powder is suitably used as the glass phase.

Mix the BaTiO ₃ calcined powder and the Ba _1-X M _X TiO ₃ powder in a specified ratio with the rare earth element compound, the Mn compound, the oxide of the alkaline earth metal element, and the organic vehicle, prepare the slurry, and then shape it to form Dielectric green sheets. For forming the dielectric green sheet, a sheet forming method such as a die coater is most suitable, and the thickness of the dielectric green sheet formed by such a forming method is preferably 5 μm or less, more preferably 4 μm or less.

Next, internal electrode patterns are formed on the surface of the dielectric green sheet. The internal electrode pattern is formed, for example, by screen printing a paste made of base metal powder such as Ni or Cu and organic resin or solvent. The thickness of the internal electrode pattern is preferably thinner than the thickness of the dielectric green sheet, 4 μm or less, from the viewpoint of reducing the level difference on the dielectric green sheet.

Next, the dielectric green sheets on which the internal electrode patterns are formed are laminated in multiple layers to form a capacitor main body molded body. Then, in the atmosphere, the capacitor body is heated to 400-500°C at a heating rate of 40-80°C/h for binder removal treatment, and thereafter, in a reducing atmosphere, the heating rate is set from 500°C to 500°C. Set at 100-400°C/h, use a temperature of 1100-1300°C, fire for 2-5 hours, then cool at a cooling rate of 80-400°C/h, and reheat at 750-1100°C in the atmosphere. oxidation treatment.

Finally, paste for external electrodes is applied to both end surfaces of the fired capacitor body, and fired in nitrogen to form external electrodes 3, whereby the multilayer ceramic capacitor of the present invention can be obtained.

<Second embodiment>

A second embodiment of the present invention will be described. The multilayer ceramic capacitor of the second embodiment has the configuration shown in FIG. 1 as in the first embodiment.

In this embodiment, BaTiO ₃ particles (BMTL) having an alkaline earth metal component concentration other than Ba of 0.2 atomic % or less coexist, and an alkaline earth metal component concentration other than Ba is 0.4 atomic % or more, preferably 0.5 to 2.5 atomic %. BaTiO ₃ particles (BMTH). Importantly, when the average particle diameter of BMTL is defined as DL and the average particle diameter of BMTH is defined as DH, DL>DH, especially DL/DH=1.1-2.

If the alkaline earth metal component concentration of BMTL particles exceeds 0.2 atomic %, and the alkaline earth metal component concentration of BMTH is less than 0.4 atomic %, the alkaline earth metal component concentrations of BMTL and BMTL are large, and it is difficult to find the dielectric strength of dielectric particles formed by the concentration difference of alkaline earth metal elements. The characteristics of the constant or temperature characteristics reduce the coexistence effect of the two dielectric particles. In addition, if the concentration of the alkaline earth metal component in BMTH exceeds 2.5 atomic %, there is a possibility that the decrease in the dielectric constant of BMTH will increase.

In addition, when the DL/DH ratio is less than 1.1, there is a possibility that the dielectric constant increases in an alternating electric field of 0.002 to 1 Vrms/μm. In addition, when the DL/DH ratio exceeds 2, there is a possibility that the capacitance-temperature characteristic may be improved. Furthermore, from the viewpoint of further improving the above-mentioned dielectric constant and temperature characteristics, DL/DH=1.1 to 1.5 is more preferable.

In addition, the alkaline earth metal component that is solid-dissolved in the BMTH particles having a high ratio of alkaline-earth metal elements is preferably at least one selected _from Mg, _Ca , and Sr. In view of the dielectric constant and its temperature characteristics, Ca is more preferred.

In addition, the average particle size of both BMTL and BMTH is preferably 0.7 μm or less, more preferably 0.6 μm or less for high insulation, and preferably 0.2 μm or more from the viewpoint of increasing the dielectric constant.

In addition, in the dielectric layer 5, the rare earth element compound preferably has the highest concentration on the grain boundary surface, that is, the grain boundary phase 15, and has a concentration gradient from the surface of the boundary grain particle to the inside of the particle, and is at least 0.05 atomic %/nm. That is, as long as the concentration gradient of the rare earth element is such a condition, it is possible to obtain a dielectric layer that can improve the dielectric constant and high-temperature load life, and can also satisfy the X7R standard as a capacitance temperature characteristic.

Here, as the rare earth element, at least one of La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, and Sc is preferable, and Y is more preferable.

In addition, the BaTiO ₃ crystalline particles of the present invention, as described above, are solid-dissolved Mg in the surface region by firing, but the concentration gradient of Mg in the surface region of the BaTiO ₃ crystalline particles prevents the diffusion and solid-solution of rare earth elements from improving. From the viewpoint of the grain boundary portion as the high concentration side, toward the inside of the grain, it is preferably 0.003 atomic %/nm or more, more preferably 0.01 atomic %/nm or more.

(Manufacturing method)

_The production method of the present invention comprises preparing BaTiO ₃ powder with an average particle diameter of 0.05 to 0.5 μm and Ba _1-X M _X TiO ₃ (M: Mg, Ca, Sr, X = 0.01 to 0.2) powder, and adding oxides of alkaline earth metal elements other than Ba to the BaTiO ₃ powder and Ba _1-X M _X TiO ₃ , respectively, and firing at a temperature of 850° C. or lower to prepare BaTiO ₃ and Ba _1-X M _X TiO ₃ (M: Mg, Ca, Sr, X = 0.01 to 0.2) the step of calcining the powder.

Here, for the BaTiO ₃ powder and the Ba _1-X M _X TiO ₃ powder, it is important to bake at a temperature of 850° C. or lower to prepare a powder in which oxides of alkaline earth metal elements are solid-dissolved on the surfaces of both powders. Furthermore, preferably, oxides of alkaline earth metal elements exist on the surfaces of both powders.

BaTiO powder and Ba _1-X M _{X TiO} powder used as the main raw materials _are preferably powders obtained by hydrothermal synthesis because of their narrow particle size distribution and high crystallinity, and their average particle diameter is preferably 0.2 μm or more. Below 0.4μm. In addition, the specific surface area of such a fine powder is preferably 1.7 to 6.6 (m ² /g). In addition, it is important that the average particle size of the Ba _1-X M _X TiO ₃ powder is smaller than the BaTiO ₃ powder, preferably 0.04-0.4 μm, more preferably 0.15-0.35 μm.

That is, in the present invention, for example, _BaTiO powder in which MgO is solid-dissolved on the surface is formed by low-temperature firing, and the AC electric field characteristics after firing are improved, and it is necessary to have a high reactivity with appropriate grain growth. For powder, therefore, it is preferable to specify the specific surface area in the above-mentioned range together with the average particle diameter.

Regarding the firing temperature, as described above, as the solid solution of MgO in BaTiO ₃ powder and Ba _1-X M _X TiO ₃ (M: Mg, Ca, Sr, X = 0.01 to 0.2) powder that suppresses the solid solution of MgO on the surface The reason for melting is preferably below 850°C, more preferably below 750°C. In addition, the firing temperature is preferably 600°C or higher, more preferably 650°C or higher, for the reason that MgO is surely diffused into a solid solution on the surface of the BaTiO ₃ powder. In addition, the average particle diameter of the MgO powder used here is preferably 0.3 μm or less from the viewpoint of increasing the coverage rate on the surface of the BaTiO ₃ powder. In the present invention, by using the BaTiO ₃ powder previously calcined with the oxide of the alkaline earth metal element in this way, the diffusion and solid solution of the rare earth element can be suppressed, and the grain growth can also be suppressed.

In this regard, for BaTiO ₃ powder and Ba _1-X M _X TiO ₃ powder, for example, if the calcination temperature for solid solution of oxides of alkaline earth metal elements such as MgO is higher than 850°C, since Mg near the grain boundary is easy to diffuse into solid solution, This promotes the diffusion and solid solution of rare earth element compounds, so it is easy to produce grain growth of dielectric particles mainly composed of barium titanate particles with a low concentration of alkaline earth metal elements other than Ba, and the temperature characteristics of electrostatic capacitance cannot meet the required characteristics. .

For the above-mentioned treatment of the present invention, in BaTiO ₃ powder and Ba _1-X M _X TiO ₃ powder, for example, without carrying out the treatment of solid solution MgO first, add BaTiO ₃ powder or Ba _1-X M _X TiO ₃ together In the case of additives such as powder and rare earth elements, it is difficult to form a solid solution of MgO in the surface layer of BaTiO ₃ . Therefore, the diffusion of the M component etc. from the Ba _1-X M _X TiO ₃ powder increases, and the original dielectric constant of BaTiO ₃ cannot be maintained, resulting in a decrease in capacitance. In addition, grain growth is easily caused. In Ba _1-X M _X TiO ₃ , it is preferable that M is Ca and that X is in the range of 0.02 to 0.1 because the permittivity can be increased and the capacitance-temperature characteristic can be flattened.

In the (a') step in this production method, the ratio of the oxides of alkaline earth metal elements other than Ba to be added, in molar ratio, is the total amount added in the (a')(b') step 30 to 60% of the oxide of the alkaline earth metal element is preferably MgO as the alkaline earth metal element, and the M component in Ba _1-X M _X TiO ₃ is preferably Ca. In addition, the dielectric layer of the present invention contains a glass phase, but Si-Li-Ca-based glass powder is suitably used as the glass phase.

Next, mix the BaTiO ₃ calcined powder and the Ba _1-X M _X TiO ₃ calcined powder in a prescribed ratio with the rare earth element compound, the Mn compound, the remaining alkaline earth metal element oxides, and the organic vehicle to prepare The slurry is then molded to form a dielectric green sheet. Forming of the above-mentioned dielectric green sheet is most suitable to use a sheet forming method such as a die coater, and the thickness of the dielectric green sheet formed by such a forming method is preferably 5 μm or less, more preferably 4 μm or less.

Next, internal electrode patterns were formed on the surface of the obtained dielectric green sheet. The internal electrode pattern is formed, for example, by screen printing a paste made of base metal powder such as Ni or Cu and organic resin or solvent. The thickness of the internal electrode pattern is preferably thinner than the thickness of the dielectric green sheet, 4 μm or less, from the viewpoint of reducing the level difference on the dielectric green sheet.

Next, the dielectric green sheets on which the internal electrode patterns are formed are laminated in multiple layers to form a capacitor main body molded body. Then, in the atmosphere, the capacitor body is heated to 400-500°C at a heating rate of 40-80°C/h for binder removal treatment, and thereafter, in a reducing atmosphere, the heating rate is increased from 500°C to Set at 100-400°C/h, use a temperature of 1100-1300°C, fire for 2-5 hours, then cool at a cooling rate of 80-400°C/h, and use 750-1100°C in an atmospheric atmosphere. re-oxidation treatment.

Finally, the paste for external electrodes is coated on both end surfaces of the fired capacitor body, and fired in nitrogen to form external electrodes 3, whereby the multilayer ceramic capacitor of the present invention can be obtained.

Other points are the same as those of the first embodiment.

Example

Hereinafter, the present invention will be described in more detail by giving examples and comparative examples, but the present invention is not limited to the following examples.

Example 1

A multilayer ceramic capacitor is fabricated as follows. First, BaTiO ₃ (BT) and (Ba _0.95 Ca _0.05 )TiO ₃ (BCT) are prepared in advance. Add and mix 0.25 mole parts of MgO to the BaTiO ₃ powder, and heat at the temperature shown in Table 1 for 2 hours. Next, 0.5 mol of Y ₂ O ₃ , 0.3 mol of MnCO ₃ , and 0.25 mol of MgO were mixed with 100 mol of the baked BaTiO ₃ powder and (Ba _0.95 Ca _0.05 )TiO ₃ powder, and the BaTiO ₃ powder + ( Ba _0.95 Ca _0.05 ) 100 parts by mass of TiO ₃ , and 0.5 parts by mass of an additional component consisting of Li ₂ O, SiO ₂ and CaO were mixed. The mixed powder was wet pulverized using a ball mill using ZrO ₂ balls with a diameter of 5 mm, and an organic binder was added to prepare a slurry.

Next, using the obtained slurry, a dielectric green sheet having a thickness of 2.5 μm was fabricated using an auxiliary plate. A conductive paste containing Ni metal was screen-printed on this dielectric green sheet to form internal electrode patterns. 388 dielectric green sheets with internal electrode patterns were laminated, and 20 dielectric green sheets without internal electrode patterns were laminated on top and bottom, respectively, and integrated with a press to obtain a laminated body.

This laminated body was cut into a lattice shape to produce a capacitor main body molded body of 2.3 mm×1.5 mm×1.5 mm.

Next, in the atmosphere, the molded body of the capacitor was heated to 500°C at a temperature increase rate of 50°C/h to perform binder removal treatment, and then the temperature increase rate from 500°C was set to 200°C/h , fired at 1200°C (oxygen partial pressure 10 ^-11 atm) for 2 hours, then cooled to 800°C at a cooling rate of 200°C/h, and re-oxidized at 800°C for 4 hours in the atmosphere. Cool at a cooling rate of ℃/h to make the capacitor body. The dielectric layer has a thickness of 2.3 μm.

Next, after barrel grinding the fired capacitor body, a paste for external electrodes containing Cu powder and glass was applied to both end surfaces, and fired at 800° C. in nitrogen to form external electrodes. Then, using an electrolytic barrel plating machine, Ni plating and Sn plating were sequentially performed on the surface of the external electrodes to fabricate a multilayer ceramic capacitor.

In addition, a sample (sample No. 7) in which BaTiO ₃ and (Ba _0.95 Ca _0.05 )TiO ₃ raw materials were baked together was produced. In addition, a sample (sample No. 8) was prepared, the particle size of BaTiO ₃ was 0.4 μm, the particle size of (Ba _0.95 Ca _0.05 )TiO ₃ was 0.35 μm, and the calcination temperature of MgO to BaTiO ₃ was 850 °C, and the composition and sequence of additives other than that are the same as the above-mentioned steps of the present invention.

In addition, only BaTiO ₃ powder, or only (Ba _0.95 Ca _0.05 )TiO ₃ powder was used, and the composition and sequence of additives other than that were the same as those in the above-mentioned process of the present invention. (Sample No.9, 10)

Next, with respect to the multilayer ceramic capacitors produced for each sample, the electrostatic capacitance and dielectric loss were measured using an LCR meter 4284A at a frequency of 1.0 kHz and an input signal level of 0.5 V. The dielectric constant is calculated from the electrostatic capacitance, the effective area of the internal electrode layer, and the thickness of the dielectric layer. Next, based on the capacitance at 25°C, temperature characteristics of the capacitance were measured in the range of -55 to 125°C. Under the conditions of a temperature of 125°C and a voltage of 9.45V, a high temperature load test was carried out for 1000 hours, and the change of insulation resistance of 30 samples was measured. In this case, a sample with no defects is defined as good. In addition, the crystal particle size and its variation were measured by using a photograph taken with an electron microscope by the blocking method.

In addition, regarding the presence of rare earth elements in the crystal grains constituting the dielectric layer, the polished cross-section samples were evaluated using a transmission electron microscope and an energy dispersive spectrometer (EDS).

In addition, regarding the concentration of Ca, an arbitrary site near the center was also analyzed using a transmission electron microscope and EDS. At this time, those with a Ca concentration higher than 0.3 atomic % (the second digit after the decimal point is rounded off) were regarded as dielectric particles with a high Ca concentration. This analysis was performed on 100 to 150 main crystal particles.

The average crystal grain size of the crystal grains in samples Nos. 1 to 6 of the present invention is 0.4 μm for the dielectric grains (BMTH) with high Ca concentration and mainly composed of Ba and Ti, and 0.4 μm for those with low Ca concentration and with Ba and Ti as main components. The dielectric particle (BMTL) mainly composed of Ti is 0.3 to 0.35 μm. In addition, the variation (CV value) of the average grain size of both BMTH and BMTL was 0.5 or less.

Table 1 Sample No. Roasting method ^** Calcination temperature ℃ BT BCT Average particle size (μm) Amount (mol%) Average particle size (μm) Ca amount× Amount (mol%) 1 Only as for BT roasting +MgO 850 0.3 50 0.35 0.05 50 2 Only as for BT roasting +MgO 850 0.3 60 0.35 0.05 40 3 Only as for BT roasting +MgO 850 0.3 40 0.35 0.05 60 4 Only as for BT roasting +MgO 850 0.35 50 0.35 0.05 50 5 Only as for BT roasting +MgO 850 0.35 60 0.35 0.05 40 6 Only as for BT roasting +MgO 850 0.35 40 0.35 0.05 60 7 BT+BCT+combined 1150 0.35 50 0.35 0.05 50 8 Only as for BT roasting +MgO 850 0.4 50 0.35 0.05 50 9 Only as for BT roasting +MgO 850 0.35 100 - - - 10 Only in BCT roasting +MgO - - - 0.35 0.05 100

^** : BT+BCT+combined, indicating that BaTiO ₃ , (Ba,M)TiO ₃ and additives were mixed together.

: Only BT roasting + MgO, means only for BaTiO ₃ , first add MgO roasting separately.

Table 2 Sample No. Crystalline particles Dielectric constant Capacity Temperature Characteristics High temperature load life 125℃, 9.45V Area ratio BMTL/BMTH BMTL BMTH Gradient of rare earth element concentration ΔC/C(%)at 125℃ ×7R - (μm) (μm) Atomic%/nm % - - 1 0.4 0.3 0.4 0.13 3190 -8.9 ○ ○ 2 0.45 0.3 0.4 0.09 3300 -11 ○ ○ 3 0.41 0.3 0.4 0.12 3050 -8.5 ○ ○ 4 0.43 0.35 0.4 0.12 3550 -14.5 ○ ○ 5 0.52 0.35 0.4 0.13 3600 -14.5 ○ ○ 6 0.47 0.35 0.4 0.12 3450 -14 ○ ○ 7 0.35 0.38 0.42 0.03 2500 -18.5 x x 8 0.9 0.45 0.4 0.16 3700 -17.5 x ○ 9 - 0.35 - 0.16 2800 -18.2 x ○ 10 - - 0.6 0.17 2000 -12 ○ x

It can be seen from Tables 1 and 2 that among samples No.1 to No.6 produced by the manufacturing method of the present invention, the dielectric constant satisfies more than 3050, and the capacitance temperature characteristics meet the X7R specification. Even at high temperatures of 125°C and 9.45V In the load test, 1000 hours were also satisfied.

In the sample No.7, the concentration gradient of rare earth elements exceeds the scope of the present invention, and the progress of solid solution causes grain growth. The average crystal grain size of the dielectric particles with high Ca concentration is greater than 0.4 μm. As mentioned above, in the dielectric When the thickness of the layer is 2.3 μm, the capacitance temperature characteristics do not satisfy the X7R standard.

In sample No. 8, since the average grain size of the dielectric particles with a low Ca concentration was larger than that of the dielectric particles with a low Ca concentration, the capacitance temperature characteristics did not satisfy the X7R specification despite a high dielectric constant.

In addition, in the sample No. 9, since all of them were dielectric particles with a low Ca concentration, the temperature characteristics of the electrostatic capacitance did not satisfy the X7R standard.

In addition, in the No. 10 sample, since all the dielectric particles with a high concentration of Ca are used, the grain growth is promoted, and the average grain size is larger than 0.4 μm. Although the capacitance-temperature characteristics are satisfactory, the dielectric constant is low and cannot meet the requirements. High temperature load life.

Example 2

A multilayer ceramic capacitor is fabricated as follows. First, with respect to 100 moles of BaTiO ₃ (BT)+(Ba _0.95 Ca _0.05 )TiO ₃ (BCT) having an average particle diameter shown in Table 3, 0.25 mol of MgO was weighed, mixed well, and heated at the temperature shown in Table 3 for 2 Hour. Next, the amount of rare earth elements shown in Table 3, 0.3 mol of MnCO ₃ , and 0.25 mol of MgO were mixed with 100 mol of the mixed powder of the baked BaTiO ₃ powder+(Ba _0.95 Ca _0.05 )TiO ₃ powder.

Next, 0.5 parts by mass of an additional component consisting of Li ₂ O, SiO ₂ and CaO was mixed with respect to 100 parts by mass of BaTiO ₃ +(Ba _0.95 Ca _0.05 )TiO ₃ . The mixed powder was wet pulverized with a ball mill using ZrO ₂ balls with a diameter of Φ5 mm, and an organic binder was added to prepare a slurry. Next, using the obtained slurry, a dielectric green sheet having a thickness of 4 μm was fabricated using an auxiliary plate.

Next, a conductive paste containing Ni metal was screen-printed on the dielectric green sheet to form internal electrode patterns. 388 dielectric green sheets with internal electrode patterns were laminated, and 20 dielectric green sheets without internal electrode patterns were laminated on top and bottom, respectively, and integrated by a press to obtain a laminated body.

This laminated body was cut into a lattice shape to produce a capacitor main body molded body of 2.3 mm×1.5 mm×1.5 mm.

Next, in the atmosphere, the molded body of the capacitor was heated to 500°C at a temperature increase rate of 50°C/h to perform binder removal treatment, and then the temperature increase rate from 500°C was set to 200°C/h , fired at 1240°C (oxygen partial pressure 10 ^-11 atm) for 2 hours, then cooled to 800°C at a cooling rate of 200°C/h, and then re-oxidized at 800°C for 4 hours in the atmosphere, Cool at a cooling rate of 200°C/h to produce a capacitor body. The thickness of the dielectric layer was 2.3 μm.

Next, after barrel grinding the fired capacitor body, a paste for external electrodes containing Cu powder and glass was applied to both end surfaces thereof, and sintered at 850° C. in nitrogen to form external electrodes. Then, using an electrolytic barrel plating machine, Ni plating and Sn plating were sequentially performed on the surface of the external electrodes to fabricate a multilayer ceramic capacitor.

Next, with respect to the produced multilayer ceramic capacitors, ie, each sample, the electrostatic capacitance and dielectric loss were measured using an LCR meter 4284A at a frequency of 1.0 kHz and an input signal level of 0.5 V. The dielectric constant is calculated from the electrostatic capacitance, the effective area of the internal electrode layer, and the thickness of the dielectric layer.

Next, based on the capacitance at 25°C, temperature characteristics of the capacitance were measured in the range of -55 to 125°C. The high temperature load test was carried out for 1000 hours under the conditions of a temperature of 125° C. and a voltage of 9.45 V, and the change of insulation resistance of 30 samples was measured. In this case, a sample with no defects is defined as good. In addition, the crystal particle size and its variation were measured by using a photograph taken with an electron microscope by the blocking method.

In addition, regarding the presence of rare earth elements in the crystal grains constituting the dielectric layer, a sample having a polished cross-section was evaluated using a transmission electron microscope and EDS.

In addition, regarding the concentration of Ca, an arbitrary site near the center was also analyzed using a transmission electron microscope and EDS. At this time, those with a Ca concentration higher than 0.3 at % (the second digit after the decimal point is rounded off) were regarded as dielectric particles with a high Ca concentration. This analysis was performed on 100 to 150 main crystal particles.

The average crystal grain size of the crystal grains in the sample of the present invention is 0.4 μm for the dielectric grain (BMTL) with a low Ca concentration and mainly composed of Ba and Ti, and for the dielectric grain (BMTL) with a high Ca concentration and mainly composed of Ba and Ti. Dielectric particles (BMTH) are 0.3 μm. In addition, the variation (CV value) of the average crystal grain size of these BMTH and BMTL particles was all 0.5 or less.

In addition, as a comparative example, when the raw material powder is specified as BaTiO ₃ : 0.4 μm and ( _Ba0.95 Ca _0.05 )TiO ₃ : 0.35 μm, the temperature for firing MgO on BaTiO ₃ is specified as 1150°C, and the The composition or steps of other additives are the same as the above-mentioned process of the present invention (No. 11). In addition, as a comparative example, only BaTiO ₃ powder or (Ba _0.95 Ca _0.05 )TiO ₃ powder was used, and other additive compositions and procedures were the same as the above-mentioned process of the present invention. (No. 12, 13)

table 3 Sample No. Roasting method Calcination temperature ℃ Roasting method Calcination temperature ℃ BT ^* 3 BCT ^* 4 Addition of rare earth elements Average particle size (μm) Amount (mol%) Average particle size (μm) Ca amount× Amount (mol%) Element mol% 11 BT+MgO are processed together 1150 BCT+MgO are processed together 1150 0.4 50 0.35 0.05 50 Y 0.5 12 BT+MgO 850 - - 0.4 100 - - - Y 0.5 13 - - BCT+MgO - - 0.35 0.05 100 Y 0.5 14 BT+MgO 850 BCT+MgO 850 0.4 70 0.35 0.05 30 Y 0.5 15 BT+MgO 850 BCT+MgO 850 0.4 50 0.35 0.05 50 Y 0.5 16 BT+MgO 850 BCT+MgO 850 0.4 50 0.35 0.05 50 Y 0.25 17 BT+MgO 850 BCT+MgO 850 0.4 50 0.35 0.05 50 Y 1 18 BT+MgO 700 BCT+MgO 700 0.35 50 0.35 0.05 50 Y 0.5 19 BT+MgO 700 BCT+MgO 700 0.35 50 0.3 0.05 50 Y 0.5 20 BT+MgO 700 BCT+MgO 700 0.35 50 0.3 0.05 50 Y 0.25 twenty one BT+MgO 700 BCT+MgO 700 0.3 50 0.25 0.05 50 Y 1

^** : BCT+MgO are processed together, indicating that BT and BCT powders are roasted together.

  BT+MgO, BCT+MgO, means roasting separately.

^* 3: BaTiO ₃ .

^* 4: Ba _1-x Ca _x TiO ₃ .

Table 4 Sample No. dielectric particles Dielectric constant Capacitance Temperature Characteristics Insulation resistance Average particle size ratio DL/DH ^* BT average particle size frequency (BMTL) ≤ 0.7μm frequency (%) Frequency of BCT average particle size (BMTH) ≤ 0.5μm frequency (%) Concentration gradient of rare earth elements atomic %/nm 0.02V/μm 0.1V/μm 1V/μm ΔC/C(%)at 125℃% ×7R GΩ 11 0.9 85 93 0.03 2600 3100 4500 -16.5 x >10 12 - 100 - 0.09 2800 2900 3500 -18.5 x >10 13 - - 97 0.12 2100 3400 6000 12.2 ○ 0.2 14 1.14 100 100 0.13 4010 4800 5500 -14.5 ○ >10 15 1.14 100 100 0.12 3800 4000 4900 -10.2 ○ >10 16 1.14 100 100 0.12 3900 4200 5200 -8.3 ○ >10 17 1.14 100 100 0.12 3400 3600 3900 -13.5 ○ >10 18 1 100 100 0.16 3780 4010 5000 -9.3 ○ >10 19 1.17 100 100 0.16 3100 3350 3700 -10.4 ○ >10 20 1.17 100 100 0.17 3350 3820 4000 -8.4 ○ >10 twenty one 1.17 100 100 0.17 3400 3500 3750 -12.6 ○ >10

^** : DL (average particle diameter of BaTiO ₃ ), DH (average particle diameter of BaCaTiO ₃ ).

It can be seen from Tables 3 and 4 that among the samples No.14-No.21 produced by the manufacturing method of the present invention, the dielectric constant reaches more than 3100 in the range of AC electric field 0.02-1Vrms/μm, and the capacitance-temperature characteristic satisfies X7R Specifications, insulation resistance also meet 10GΩ.

In addition, sample No. 11, which was baked at 1150°C, reached DL/DH=0.9, and the temperature characteristic of the electrostatic capacity was improved, so that the X7R characteristic could not be satisfied.

Furthermore, even in the case where BMTL is used alone, the X7R characteristics cannot be satisfied. In addition, in the case of dielectric particles of BMTH alone, the insulation resistance was as low as 0.2 GΩ.

Claims (25)

1. A laminated ceramic capacitor is composed of alternately laminated dielectric layers and internal electrode layers, characterized in that: On the dielectric layer, BMTL is barium titanate particles containing alkaline earth metal components other than Ba in a ratio of 0.2 atomic % or less, and barium titanate containing alkaline earth metal components other than Ba in a ratio of 0.4 atomic % or more. The particles, BMTH, coexist at an area ratio of BMTL/BMTH=0.1-9. 2. The multilayer ceramic capacitor according to claim 1, wherein the dielectric layer satisfies DL≤DH when the average particle diameter of BMTL is defined as DL and the average particle diameter of BMTH is defined as DH. relation. 3. The multilayer ceramic capacitor according to claim 1, wherein the alkaline earth metal component is at least one selected from Mg, Ca, and Sr. 4. The multilayer ceramic capacitor according to claim 1, wherein the average particle size of both BMTL and BMTH is 0.5 μm or less. 5. The multilayer ceramic capacitor according to claim 1, wherein the dielectric layer has a thickness of 4 μm or less. 6. The multilayer ceramic capacitor according to claim 1, wherein the internal electrode layer contains a base metal as a main component. 7. The multilayer ceramic capacitor according to claim 1, wherein the dielectric layer satisfies DL>DH when the average particle diameter of BMTL is defined as DL and the average particle diameter of BMTH is defined as DH. relation. 8. The multilayer ceramic capacitor according to claim 1, wherein said BMTH contains an alkaline earth metal component other than Ba in a ratio of 0.5 to 2.5 at%. 9. The multilayer ceramic capacitor according to claim 7, wherein DL/DH=1.1-2. 10. The multilayer ceramic capacitor according to claim 7, wherein the alkaline earth metal component is at least one selected from Mg, Ca, and Sr. 11. The multilayer ceramic capacitor according to claim 7, wherein the average particle size of both BMTL and BMTH is 0.7 μm or less. 12. The multilayer ceramic capacitor according to claim 7, wherein both BMTL and BMTH contain rare earth elements, and the concentration gradient of the rare earth elements is the highest concentration on the particle surface, and the concentration gradient from the surface to the inside is 0.05. Atomic %/nm or more. 13. The multilayer ceramic capacitor according to claim 7, wherein the dielectric layer has a thickness of 4 μm or less. 14. The multilayer ceramic capacitor according to claim 7, wherein the internal electrode layer contains a base metal as a main component. 15. A method for manufacturing a laminated ceramic capacitor, comprising the following steps: (a) adding oxides of alkaline earth metal elements other than Ba to _BaTiO3 powder, and roasting at a temperature below 850°C to prepare _BaTiO3 roasted powder; (b) mix the BaTiO ₃ calcined powder with Ba _1-X M _X TiO ₃ powder, rare earth element compounds, Mn compounds, oxides of alkaline earth metal elements other than Ba, and an organic vehicle to prepare a slurry, Then molding to form a dielectric green sheet, wherein M is Mg, Ca or Sr, and X=0.01-0.2; (c) a step of forming an internal electrode pattern on the surface of the dielectric green sheet; (d) A step of laminating a plurality of dielectric green sheets on which internal electrode patterns are formed, followed by firing. 16. The method of manufacturing a multilayer ceramic capacitor according to claim 15, wherein the ratio of the oxide of the alkaline earth metal element added in the step (a) is, by molar ratio, the ratio in the step (a) (b) 30-70% of the oxides of the total alkaline earth metal elements added in the 17. The method of manufacturing a multilayer ceramic capacitor according to claim 15, wherein the oxide of the alkaline earth metal element to be added is MgO. 18. The method for manufacturing a laminated ceramic capacitor according to claim 15, wherein M in the Ba _1-X M _X TiO ₃ powder is Ca. 19. The method for manufacturing a laminated ceramic capacitor according to claim 15, wherein the average particle size of the BaTiO ₃ powder and the Ba _1-X M _X TiO ₃ powder is 0.4 μm or less. 20. The method of manufacturing a multilayer ceramic capacitor according to claim 15, wherein said internal electrode pattern contains a base metal as a main component. 21. A method for manufacturing a laminated ceramic capacitor, comprising the following steps: ( _a ') adding an alkaline earth metal oxide other than Ba to each of BaTiO ₃ powder with an average particle diameter of 0.05 to 0.5 μm and Ba _1-X M _X TiO ₃ powder with an average particle diameter smaller than the BaTiO 3 powder. The product is roasted at a temperature below 850 ° C to prepare BaTiO ₃ roasted powder and Ba _1-X M _X TiO ₃ roasted powder, wherein M is Mg, Ca or Sr, and X = 0.01 to 0.2; (b') The BaTiO ₃ roasted powder and Ba _1-X M _X TiO ₃ roasted powder are mixed with rare earth element compounds, Mn compounds, alkaline earth metal oxides and organic vehicles to prepare a slurry, and then molded to form Dielectric green sheet process; (c') a step of forming an internal electrode pattern on the surface of the dielectric green sheet; (d') A step of laminating a plurality of dielectric green sheets on which internal electrode patterns are formed, followed by firing. 22. The method for manufacturing a multilayer ceramic capacitor as claimed in claim 21, wherein the ratio of the alkaline earth metal oxide added in the step (a') is in terms of molar ratio (mass ratio) in (a')( b') 30 to 60% of the total alkaline earth metal oxides added in the step. 23. The method of manufacturing a multilayer ceramic capacitor according to claim 21, wherein the alkaline earth metal oxide is MgO. 24. The method for manufacturing a laminated ceramic capacitor according to claim 21, wherein M in the Ba _1-X M _X TiO ₃ powder is Ca. 25. The method of manufacturing a multilayer ceramic capacitor according to claim 21, wherein said internal electrode pattern contains a base metal as a main component.

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