阅读说明：本技术 电介质、电子器件和层叠陶瓷电容器 (Dielectric, electronic device, and laminated ceramic capacitor ) 是由 斋藤裕太 萩原智也 于 2021-05-07 设计创作，主要内容包括：本发明涉及并提供电介质、电子器件和层叠陶瓷电容器。本发明的电介质包括具有双晶结构的核-壳粒子,其中核-壳粒子的双晶结构的界面从一侧的壳延伸,穿过核,并延伸到另一侧的壳。根据本发明,电介质、电子器件和层叠陶瓷电容器可具有改善的可靠性。(The invention relates to and provides a dielectric, an electronic device and a laminated ceramic capacitor. The dielectric of the present invention includes core-shell particles having a twinned structure, wherein the interface of the twinned structure of the core-shell particles extends from the shell on one side, through the core, and to the shell on the other side. According to the present invention, a dielectric, an electronic device, and a laminated ceramic capacitor can have improved reliability.)

1. A dielectric, comprising:

a core-shell particle having a twinned structure,

wherein the interface of the twinned structure of the core-shell particle extends from the shell on one side, through the core, and to the shell on the other side.

2. The dielectric of claim 1, wherein an interface of the bimorph structure contacts a grain boundary of the core-shell particle.

3. The dielectric according to claim 1 or 2, wherein a proportion of the number of core-shell particles to the crystal grains in the dielectric is 2% or more and 20% or less.

4. The dielectric according to any one of claims 1 to 3, wherein the main component of the core-shell particles is an oxide of Ba and Ti.

5. The dielectric of any of claims 1 to 4, wherein the core-shell particles comprise an oxide of a rare earth element and include at least one of an oxide of Mg, V, Mn, Zr, and Cr.

6. The dielectric of any of claims 1 to 3, further comprising:

the amount of the ceramic as the main component of the dielectric is 100 mol% and Re as a rare earth element is converted to Re₂O₃1.75 to 3.50 mol% of an oxide of a rare earth element Re, wherein Re represents at least one of the rare earth elements; and

assuming that the amount of the ceramic as the main component of the dielectric is 100 mol% and oxides of Mg, V, Mn, Zr and Cr are converted into MgO and MnO₂、ZrO₂、V₂O₅And Cr₂O₃When used, the total amount is 0.02 to 2.05 mol% of oxides of Mg, V, Mn, Zr, and Cr.

7. The dielectric according to any one of claims 1 to 6, further comprising an oxide of Si.

8. The dielectric according to claim 7, further comprising a step of setting an amount of the ceramic as a main component of the dielectric to 100 mol% and Si to SiO₂0.25 to 2.50 mol% of an oxide of Si.

9. An electronic device comprising the dielectric according to any one of claims 1 to 8.

10. A laminated ceramic capacitor, comprising:

a stacked structure in which each of the dielectric layers is alternately stacked with each of the internal electrode layers, each of the dielectric layers including core-shell particles having a bimorph structure,

wherein the interface of the twinned structure of the core-shell particle extends from the shell on one side, through the core, and to the shell on the other side.

11. The laminated ceramic capacitor of claim 10, wherein the interface of the bimorph structure contacts the grain boundary of the core-shell particles.

12. The laminated ceramic capacitor according to claim 10 or 11, wherein a proportion of core-shell particles with respect to crystal grains in one of the dielectric layers is 2% or more and 20% or less.

13. The laminated ceramic capacitor according to any one of claims 10 to 12, wherein the main component of the core-shell particles is an oxide of Ba and Ti.

14. The laminated ceramic capacitor of any one of claims 10 to 13, wherein the core-shell particles comprise an oxide of a rare earth element and include at least one of an oxide of Mg, V, Mn, Zr, and Cr.

15. The laminated ceramic capacitor of any one of claims 10 to 12, wherein one of the dielectric layers comprises: the amount of the ceramic as the main component of the dielectric layer is 100 mol% and Re as a rare earth element is converted to Re₂O₃1.75 to 3.50 mol% of an oxide of a rare earth element Re, wherein Re represents at least one of the rare earth elements; and is

Wherein the one dielectric layer comprises: the amount of the ceramic as the main component of the dielectric layer is 100 mol%, and the oxides of Mg, V, Mn, Zr and Cr are converted into MgO and MnO₂、ZrO₂、V₂O₅And Cr₂O₃The total amount of the oxides of Mg, V, Mn, Zr and Cr is 0.02 mol% to 2.05 mol%.

16. The laminated ceramic capacitor of any one of claims 10 to 15, wherein the dielectric layer comprises an oxide of Si.

17. The laminated ceramic capacitor of claim 16, wherein said dielectric layer comprises a dielectric layer disposed thereonThe amount of the ceramic as the main component is 100 mol% and Si is converted to SiO₂0.25 to 2.50 mol% of Si oxide.

Technical Field

Certain aspects of the present invention relate to a dielectric, an electronic device, and a laminated ceramic capacitor.

Background

As the size of electronic devices decreases and the capacity of electronic devices increases, the thickness of dielectric layers of electronic devices such as laminated ceramic capacitors decreases and the number of dielectric layers increases (see, for example, japanese patent application laid-open No. 2017-178684, japanese patent application laid-open No. 2017-178685, and japanese patent application laid-open No. 2002-362971).

Disclosure of Invention

However, as the thickness of the dielectric layer is reduced, the intensity of the DC electric field applied to the dielectric layer increases. Therefore, improvement in reliability of the dielectric layer is required.

An object of the present invention is to provide a dielectric, an electronic device, and a laminated ceramic capacitor capable of improving reliability.

According to one aspect of the present invention, there is provided a dielectric comprising: a core-shell particle having a twinned structure, wherein the interface of the twinned structure of the core-shell particle extends from the shell on one side, through the core, and to the shell on the other side.

According to another aspect of the invention, an electronic device is provided comprising the dielectric.

According to another aspect of the present invention, there is provided a laminated ceramic capacitor including: a stacked structure in which each dielectric layer and each internal electrode layer are alternately stacked, each dielectric layer including core-shell particles having a twinned structure, wherein an interface of the twinned structure of the core-shell particles extends from a shell of one side, passes through a core, and extends to a shell of the other side.

Drawings

Fig. 1 shows a partial perspective view of a laminated ceramic capacitor;

FIG. 2A shows a cross-sectional view of a core-shell particle having a twinned structure;

fig. 2B shows a core-shell particle having a bimorph structure observed by back-scattered electron images;

FIG. 2C schematically shows a cross-section of a dielectric layer;

FIG. 3 shows a method of manufacturing a laminated ceramic capacitor; and is

Fig. 4A to 4C illustrate a stacking process.

Detailed Description

Embodiments will be described with reference to the accompanying drawings.

[ embodiment ]

Fig. 1 is a perspective view of a laminated ceramic capacitor 100 according to an embodiment, in which a partial cross section of the laminated ceramic capacitor 100 is shown. As shown in fig. 1, the laminated ceramic capacitor 100 includes a laminated chip 10 having a rectangular parallelepiped shape, and a pair of external electrodes 20a and 20b provided respectively on both end faces of the laminated chip 10 that are opposed to each other. Of the four surfaces other than the two end surfaces of the laminated chip 10, two surfaces other than the upper and lower surfaces of the laminated chip 10 in the stacking direction are referred to as side surfaces. The external electrodes 20a and 20b extend to both upper and lower faces and both side faces. But the outer electrodes 20a and 20b are spaced apart from each other.

The stacked chip 10 has a structure designed to have dielectric layers 11 and internal electrode layers 12 alternately stacked. The main component of the dielectric layer 11 is a ceramic material used as a dielectric material. The main component of the internal electrode layers 12 is a metal material, such as a base metal material. The edges of the internal electrode layers 12 are alternately exposed to a first end face of the laminated chip 10 and a second end face of the laminated chip 10 different from the first end face. In the present embodiment, the first end surface faces the second end surface. The external electrode 20a is provided on the first end face. The external electrode 20b is disposed on the second end face. Thereby, the internal electrode layers 12 are alternately conducted to the external electrodes 20a and the external electrodes 20 b. Therefore, the multilayer ceramic capacitor 100 has a structure in which a plurality of dielectric layers 11 are stacked with the internal electrode layer 12 sandwiched between every two dielectric layers 11. In the stacked structure of the dielectric layers 11 and the internal electrode layers 12, the outermost layer in the stacking direction is the internal electrode layers 12. The upper and lower surfaces of the laminated structure are internal electrode layers 12 covered with a cover layer 13. The main component of the cover layer 13 is a ceramic material. For example, the main component of the cover layer 13 is the same as that of the dielectric layer 11.

For example, the laminated ceramic capacitor 100 may have a length of 0.25mm, a width of 0.125mm, and a height of 0.125 mm. The laminated ceramic capacitor 100 may have a length of 0.4mm, a width of 0.2mm and a height of 0.2 mm. The laminated ceramic capacitor 100 may have a length of 0.6mm, a width of 0.3mm and a height of 0.3 mm. The laminated ceramic capacitor 100 may have a length of 1.0mm, a width of 0.5mm and a height of 0.5 mm. The laminated ceramic capacitor 100 may have a length of 3.2mm, a width of 1.6mm and a height of 1.6 mm. The laminated ceramic capacitor 100 may be 4.5mm long, 3.2mm wide and 2.5mm high. However, the size of the laminated ceramic capacitor 100 is not limited.

The main component of the internal electrode layers 12 is a base metal such as nickel (Ni), copper (Cu), tin (Sn), or the like. A noble metal such as platinum (Pt), palladium (Pd), silver (Ag), gold (Au), or an alloy thereof may be used as the internal electrode layers 12.

The dielectric layer 11 is mainly composed of a material represented by the general formula ABO₃Ceramic material represented and having a perovskite structure. The perovskite structure comprises an ABO having a non-stoichiometric composition_3-α. For example, the ceramic material is BaTiO₃(barium titanate), CaZrO₃(calcium zirconate), CaTiO₃(calcium titanate), SrTiO₃(strontium titanate) and Ba having perovskite Structure_1-x-yCa_xSr_yTi_1-zZr_zO₃(0≤x≤1，0≤y≤1，0≤z≤1)。

The dielectric layer 11 includes an additive compound in addition to the main component ceramic material according to the purpose. The additive compound may be an oxide of Mo (molybdenum), Nb (niobium), Ta (tantalum), W (tungsten), Mg (magnesium), Mn (manganese), V (vanadium), Cr (chromium), Zr (zirconium), or a rare earth element (Y (yttrium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium)), or an oxide of Co (cobalt), Ni (nickel), Li (lithium), B (boron), Na (sodium), K (potassium), and Si (silicon), or glass.

As the size of the laminated ceramic capacitor 100 decreases and the capacity of the laminated ceramic capacitor 100 increases, it is required to decrease the thickness of the dielectric layers 11 and increase the number of stacked dielectric layers 11. However, as the thickness of the dielectric layer 11 decreases, the DC electric field strength in the dielectric layer 11 increases. Therefore, improvement in reliability of the dielectric layer 11 is required.

The reliability of the dielectric layer 11 will be explained. The dielectric layer 11 has a main phase formed by the general formula ABO₃The perovskite-structured ceramic material powder is shown. The ceramic material powder is exposed to a reducing atmosphere during firing. Thus, ABO in ceramic material powders₃In which oxygen vacancies occur. During operation of the laminated ceramic capacitor 100, a voltage is repeatedly applied to the dielectric layers 11. In this case, oxygen vacancies migrate, and the potential barrier may be broken. That is, oxygen vacancies in the perovskite structure are one of the causes of the reliability degradation of the dielectric layer 11.

Therefore, in the present embodiment, at least a part of crystal grains of the main component ceramic of the dielectric layer 11 have a core-shell structure in which both the shell and the core have a twinned structure. Fig. 2A shows a cross-sectional view of core-shell particles 30 of dielectric layer 11. In fig. 2A, hatching is omitted. The core-shell particles 30 are crystal grains of a ceramic that is a main component of the dielectric layer 11. When the main component ceramic of the dielectric layer 11 is barium titanate, the core-shell particles 30 are crystal grains of barium titanate.

As shown in fig. 2A, the core-shell particle 30 has a spherical core 31 and a shell 32 surrounding and covering the core 31. The core 31 is a crystal portion in which there is no solid solution additive or the amount of the solid solution additive is small. The shell 32 has a crystal portion in which an additive is dissolved in a solid state and the concentration of the additive is higher than that in the core 31.

The core-shell particle 30 has a twinned structure. Interface 33 of the twinned structure of core-shell particle 30 extends from the grain boundary of core-shell particle 30, through shell 32 on one side, core 31, and shell 32 on the other side, and to the grain boundary of core-shell particle 30. In this manner, interface 33 of the twinned structure of core-shell particle 30 extends continuously from the grain boundary of core-shell particle 30 on one side, through core 31 and to the grain boundary on the other side. In this way, the range of the interface 33 is wide. In fig. 2A, a line of the interface 33 is shown. However, the plurality of interfaces 33 may be formed in a band shape. When a cross section of the core-shell particle 30 is observed, the grain boundary may be spaced apart from the interface of the bimorph structure. In this case, the separation distance may be 5nm to 25 nm.

The method of distinguishing between the core 31 and the shell 32 in the core-shell particle 30 is not limited. The core 31 and the shell 32 can be distinguished by: the dielectric layer 11 was made thin so that the surface of the dielectric layer 11 could be observed using a STEM (scanning transmission electron microscope), the cross section was observed using a STEM, an element mapping image was obtained using EDS (energy dispersive X-ray spectroscopy), and the contrast of the element mapping image was confirmed. From the viewpoint of observation using EDS, it is preferable to observe a plurality of visual fields at a magnification of 10000 times to 150000 times. The calculation method of the cross-sectional areas of the core 31 and the shell 32 is not limited. For example, each cross-sectional area of the core 31 and the shell 32 can be calculated by performing image processing on element mapping images of 20 core-shell particles 30 obtained through EDS and counting the number of pixels per region of the core 31 and the shell 32. When calculating the total area of the core 31 and the shell 32, the proportion of the core 31 is preferably 20% to 95%. The proportion of the core 31 is more preferably 40% to 85%. The proportion of the core 31 is still more preferably 60% to 80%.

In the interface 33, atomic defects may be formed. Thus, oxygen vacancies may be trapped in the interface 33. In the core-shell particle 30, the interface 33 is widely formed. Therefore, the performance of trapping oxygen vacancies is high. When the dielectric layer 11 includes the core-shell particles 30, the reliability of the dielectric layer 11 is improved.

It is considered that the reliability of the dielectric layer 11 can be ensured by increasing the proportion of the diffused phase in the dielectric layer 11. The rare earth element is diffused into the main component ceramic of the diffusion phase. However, when the proportion of the diffusion phase is too large, the temperature characteristics may deteriorate. On the other hand, when the core-shell particles 30 are formed in the dielectric layer 11, reliability is improved. Therefore, deterioration of the temperature characteristics of the dielectric layer 11 can be suppressed.

By observing the back-scattered electron image using SEM (scanning electron microscope), it can be determined whether or not the core-shell particles have a bimorph structure. As shown in fig. 2B, in the core-shell particle having a twinned structure, a contrast difference caused by different crystal orientations at a twinned interface and a concentric contrast difference caused by different compositions between the core and the shell are observed. In general, the presence of the bimorph structure can be confirmed by observing the crystal orientation of the bimorph structure using a TEM (transmission electron microscope). Therefore, the interface 33 can be confirmed by observing SEM or TEM. The object of observation is a cross section of the core-shell particle.

Fig. 2C schematically shows a cross-section of the dielectric layer 11. As shown in fig. 2C, the dielectric layer 11 has a plurality of crystal grains 14 whose main component is ceramic. At least a portion of grains 14 are core-shell particles 30 of fig. 2A.

When the proportion of the core-shell particles 30 in the dielectric layer 11 is small, sufficient trapping of oxygen vacancies is not necessarily achieved. Therefore, it is preferable that the ratio of all the core-shell particles 30 in each dielectric layer 11 has a lower limit. For example, the proportion of the number of core-shell particles 30 to all crystal grains 14 in each dielectric layer 11 is preferably 2% or more. The ratio is more preferably 8% or more. The proportion of the core-shell particles 30 can be calculated by confirming 300 crystal grains randomly selected in a plurality of fields of view of a backscattered electron image of an SEM (scanning electron microscope) image having a magnification of 10000 to 50000.

On the other hand, when the proportion of the core-shell particles 30 in each dielectric layer 11 is large, the temperature characteristics may deteriorate due to the growth of crystal grains. Therefore, it is preferable that the ratio of all the core-shell particles 30 in each dielectric layer 11 has an upper limit. For example, the proportion of all the core-shell particles 30 in each dielectric layer 11 is preferably 20% or less. The ratio is more preferably 12% or less.

The rare earth element in the additive compound of the dielectric layer 11 improves the reliability of the dielectric layer 11. Therefore, it is preferable to add a rare earth element to the dielectric layer 11. Therefore, it is preferable that the addition amount of the rare earth element in each dielectric layer 11 has a lower limit. On the other hand, when the addition amount of the rare earth element in the dielectric layer 11 is large, the proportion of the diffusion phase in which the rare earth element diffuses into the main component ceramic increases, and the temperature characteristics of the laminated ceramic capacitor 100 may deteriorate. Therefore, the amount of the rare earth element added in the dielectric layer 11 preferably has an upper limit. In the present embodiment, the amount of the ceramic as the main component of the dielectric layer 11 is 100 mol% and the rare earth element is converted to Re₂O₃When it is preferable that the amount of the rare earth element Re (Re represents at least one of the rare earth elements) is 1.75 mol% to 3.50 mol%. The amount of the rare earth element Re is more preferably 2.00 mol% to 2.75 mol%. The amount of the rare earth element Re is still more preferably 2.25 mol% to 2.50 mol%. Even if Re is generated during firing of the laminated chip 10₂O₃Diffusion, Re₂O₃But also at any position. Therefore, when the laminated structure between the two cap layers 13 was analyzed by ICP analysis, Re was detected at this ratio₂O₃。

Mg, V, Mn, Zr, and Cr in the additive compounds of the dielectric layer 11 promote sintering during firing of the dielectric layer 11. Therefore, the amount of Mg, V, Mn, Zr, and Cr added to the dielectric layer 11 preferably has a lower limit. On the other hand, the addition amounts of Mg and Zr in the dielectric layer 11 are large, grain growth is suppressed and the formation of twins may be suppressed. When the amounts of Mg, V, Mn and Cr added are large, excessive amounts may occurThe acceptor causes an increase in the oxygen vacancy concentration, resulting in a decrease in lifetime. When the addition amounts of V, Mn and Cr in the dielectric layer 11 are large, the DC bias characteristic, the aging characteristic, and the like may deteriorate. Therefore, the amount of Mg, V, Mn, Zr, and Cr added in the dielectric layer 11 preferably has an upper limit. In the present embodiment, when the amount of the ceramic as the main component of the dielectric layer 11 is 100 mol%, the total amount of the oxides of Mg, V, Mn, Zr, and Cr is preferably 0.02 mol% to 2.05 mol%, where the oxides of Mg, V, Mn, Zr, and Cr are expressed as MgO and MnO₂、ZrO₂、V₂O₅And Cr₂O₃. The addition amount is more preferably 0.10 mol% to 1.00 mol%. The addition amount is still more preferably 0.15 to 0.80 mol%.

Si in the additive compound added to the dielectric layer 11 acts as a sintering aid and lowers the sintering temperature. Therefore, the amount of Si added in each dielectric layer 11 preferably has a lower limit. On the other hand, when the amount of Si added in each dielectric layer 11 is large, the dielectric constant of the dielectric layer 11 may decrease. Therefore, it is preferable that the amount of Si added in each dielectric layer 11 has an upper limit. In the present embodiment, the amount of the ceramic as the main component of the dielectric layer 11 is 100 mol%, and the oxide of Si is converted to SiO₂In this case, the amount of the oxide of Si is preferably 0.25 to 2.50 mol%. The amount of the oxide of Si is more preferably 1.00 mol% to 2.00 mol%. The amount of the oxide of Si is still more preferably 1.50 to 1.80 mol%.

A method for manufacturing the laminated ceramic capacitor 100 will be explained. Fig. 3 shows a method for manufacturing the laminated ceramic capacitor 100.

(Process for producing raw Material powder) (S1) the A-site element and the B-site element contained in the dielectric layer 11 are usually ABO₃The sintered structural form of the particles is contained in the dielectric layer 11. For example, BaTiO₃Is a tetragonal compound having a perovskite structure and exhibits a high dielectric constant. BaTiO 2₃It is generally obtained by reacting a titanium raw material such as titanium dioxide with a barium raw material such as barium carbonate to synthesize barium titanate. As a method for synthesizing the ceramic of the dielectric layer 11, various methods are known. For example, a solid phase method, a sol-gel method, a method for producing a method, a method for producing a film, and a film, a method for producing a film, a method for producing a method for a film, a method for example, a film, a method for a film, a method,Hydrothermal method, etc. Any of the above-described methods may be employed in the present embodiment.

Next, an additive compound may be added to the ceramic powder material according to the purpose. The additive compound may be an oxide of Mo, Nb, Ta, W, Mg, Mn, V, Cr or a rare earth element (Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) or an oxide of Co, Ni, Li, B, Na, K and Si, or glass.

For example, the average particle diameter of the ceramic powder is preferably 50nm to 300nm from the viewpoint of reducing the thickness of the dielectric layer 11. For example, the particle size of the obtained ceramic can be adjusted by pulverizing ceramic powder. Alternatively, the particle size may be adjusted by performing the pulverizing and classifying process. Through these processes, a dielectric material is obtained.

(manufacturing process of metal conductive paste) (S2) the metal conductive paste is manufactured by mixing a metal material, a co-material, and an organic binder. From the viewpoint of reducing the thickness of the internal electrode layers 12, the particle diameter of the metal material is small. In the present embodiment, the metal material is a metal (e.g., Ni) having an average particle diameter of 120nm or less. Ceramic particles serving as a co-material are added to the metal conductive paste. The main component ceramic in the ceramic particles is not limited. The main component ceramic of the ceramic particles is preferably the same as that of the dielectric layer 11. Therefore, the co-material is barium titanate or the like.

(stacking process) (S3) next, a binder such as a polyvinyl butyral (PVB) resin, an organic solvent such as ethanol or toluene, and a plasticizer are added to the resulting dielectric material and wet-mixed. Using the obtained slurry, as shown in fig. 4A, a tape-shaped dielectric green sheet 41 having a thickness of 0.8 μm or less is coated on a substrate by, for example, die coating or doctor blading, and then dried. In fig. 4A, the substrate is not shown.

Next, as shown in fig. 4B, a metal conductive paste 42 for internal electrode layers is formed on the surface of the dielectric green sheet 41 by screen printing or gravure printing. The metal conductive paste 42 includes an organic binder. Thereby, the sheet member 43 is obtained.

Thereafter, as shown in fig. 4C, a predetermined number of sheet members 43 are stacked while peeling off the substrate so that the end edges of the metal conductive paste 42 are alternately exposed to both end surfaces of the dielectric green sheet 41 in the longitudinal direction. For example, 100 to 500 stacked units are stacked. After that, cover sheets to be the cover layers 13 are press-bonded to the upper and lower faces of the laminated structure of the stacked sheet members 43 to obtain a ceramic laminated structure. Thereafter, a metal conductive paste was applied to both end faces of the ceramic laminated structure by a dip coating method to serve as the external electrodes 20a and 20 b. Thereafter, the metal conductive paste is dried. Thus, a molded body for forming the laminated ceramic capacitor 100 was obtained.

The metal conductive paste 42 corresponding to the internal electrode layers 12 may be printed on a plurality of regions of the single dielectric green sheet 41. In this case, the obtained sheet members 43 are stacked. The cover sheet is clamped. After that, the stacked sheet member 43 is cut into chips having a predetermined size (e.g., 1.0mm × 0.5 mm). A metal conductive paste serving as a base layer of the external electrodes 20a and 20b is applied onto both end faces of the chip by a dip coating method or the like, and dried.

(firing Process) (S4) Next, in N₂Removing the binder at 250-500 ℃ in an atmosphere, and subjecting the obtained molded article to a partial pressure of oxygen of 10^-5～10^-8Firing at a temperature ranging from 1100 to 1300 degrees Celsius for 10 minutes to 2 hours under a reducing atmosphere of atm.

(temperature holding step) (S5), the molded article thus obtained is held for 20 minutes at a temperature 300 ℃ lower than the maximum temperature of the firing step (for example, 880 ℃ C.) in a reducing atmosphere having a higher oxygen partial pressure than the firing step. After that, the obtained molded body was cooled. Thereby, a sintered structure is obtained.

After the (reoxidation step) (S6), N may be added₂The reoxidation step is carried out at 600 to 1000 ℃ in a gas atmosphere.

(plating process) (S7), a metal layer such as Cu, Ni, or Sn is applied to the bottom layers of the external electrodes 20a and 20b through the plating process.

In the manufacturing method of the present embodiment, after the firing step, a temperature holding step is performed for a predetermined time, and the temperature is held at a temperature lower than the maximum temperature in the firing step. Thereafter, cooling is performed. In this case, the grain growth of the main component ceramic of the dielectric material is promoted. Thereby enabling the formation of core-shell particles 30 in the dielectric layer 11.

Preferably, the temperature and time of the temperature maintaining process are adjusted according to the degree of particle growth of the main component ceramic. For example, the temperature and time of the temperature holding step are preferably adjusted so that the average crystal grain diameter of the crystal grains 14 in the dielectric layer 11 is 3 times or more the average grain diameter of the ceramic that is the main component of the dielectric material. When adding Mg oxide for suppressing the growth of particles to the dielectric material, the additive amount of Mg oxide is preferably considered.

In the above embodiments, a laminated ceramic capacitor has been described as an example of the ceramic electronic device. However, the ceramic electronic device is not limited to the laminated ceramic capacitor. For example, the ceramic electronic device may be other electronic devices such as a varistor and a thermistor.

Examples

In example 1, each material was weighed so as to be converted to BaTiO₃When the amount of the oxide of Ba and Ti is 100 mol%, in terms of Dy₂O₃The amount of Dy oxide was 2.00 mol%, the amount of Mg oxide was 0.10 mol% when converted to MgO, and the amount was V when converted to₂O₅When the amount of V oxide is 0.075 mol%, when converted to SiO₂The amount of Si oxide in the case of Si is 1.50 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours.

Next, the mixed material was dried and calcined in air at 800 ℃. Thus obtaining a calcined powder. The calcined particle had an average particle diameter of 97 nm. The calcined powder was wet-pulverized in ethanol and dried. An organic binder and a solvent are added to the resulting calcined powder. The resulting slurry was formed into a ceramic green sheet having a thickness of 4 μm by a doctor blade method. Next, an internal electrode pattern was printed on the ceramic green sheet using a conductive paste whose main component was Ni powder. 10 sheets were stacked and hot pressed. Thereby obtaining a laminated structure. Punching the laminated structure into 1005 shape(1.0 mm in length, 0.5mm in width, 0.5mm in height). A laminated structure having a chip shape is obtained. Next, Ni external electrodes were formed on the chip-like laminated structure. In N₂The adhesive was removed from the resulting chip-like laminated structure under an atmosphere. The chip-like laminated structure was heated at 1200 ℃ to 10 DEG C^-5To 10^-8atm oxygen partial pressure for 15 minutes. Then, as a temperature holding step, the chip-like laminated structure was heated at 800 ℃ to 10 DEG C^-4To 10^{- 7}Oxygen partial pressure of atm for 20 minutes. After that, the chip-like laminated structure is cooled. And a chip-like sintered structure is obtained. Next, in N₂The chip-like sintered structure is subjected to a reoxidation step at 800 to 1000 ℃ in an atmosphere. Thereby obtaining a laminated ceramic capacitor. The thickness of one layer of the laminated ceramic capacitor was about 3 μm. The average grain diameter of the grains 14 in the sintered structure is 352nm, which is three times or more the size of the material powder.

Next, the laminated ceramic capacitor is embedded in an epoxy resin. The laminated ceramic capacitor is polished so as to expose the intersection portion of the internal electrodes. A back-scattered electron image obtained by SEM was observed for the dielectric layer between the internal electrode layers. The proportion of core-shell particles 30 in 300 grains 14 randomly selected from the backscattered electron image is determined.

(example 2) in example 2, the firing temperature was 20 ℃ higher than that in example 1. Other conditions were the same as in example 1. In example 2, the average particle diameter of the calcined powder was 97 nm. The average grain diameter of the crystal grains 14 is 467 nm.

Example 3 in example 3, BaTiO₃Has an average particle diameter of 20nm larger than that of example 1. Other conditions were the same as in example 1. In example 3, the average particle size of the calcined powder was 122 nm. The average grain diameter of the grains 14 is 263 nm.

(example 4) in example 4, the firing temperature was 20 ℃ higher than that in example 3. Other conditions were the same as in example 3. In example 4, the average particle size of the calcined powder was 122 nm. The average grain diameter of the grains 14 is 315 nm.

(example 5) in example 5, the firing temperature was 20 ℃ higher than that in example 4. Other conditions were the same as in example 1. In example 5, the average particle size of the calcined powder was 122 nm. The average grain diameter of the crystal grains 14 is 417 nm.

Example 6 in example 6, BaTiO₃Has an average particle diameter of 120nm larger than that of example 1. Other conditions were the same as in example 2. In example 6, the average particle size of the calcined powder was 218 nm. The average grain diameter of the grains 14 is 316 nm.

Comparative example 1 in comparative example 1, the step of maintaining the temperature at 880 c for 20 minutes was not performed, but cooling was performed from the highest temperature in the firing step, as compared with example 6. Other conditions were the same as in example 1. In comparative example 1, the average particle size of the calcined powder was 218 nm. The average grain diameter of the grains 14 is 254 nm.

Comparative example 2 in comparative example 2, the step of maintaining the temperature at 880 c for 20 minutes was not performed, but cooling was performed from the highest temperature in the firing step, as compared with example 1. BaTiO 2₃Has an average particle diameter of 220nm larger than that of example 1. Other conditions were the same as in example 2. In comparative example 2, the average particle diameter of the calcined powder was 321 nm. The average grain diameter of the grains 14 is 343 nm.

Comparative example 3 in comparative example 3, the firing temperature was 20 ℃ higher than that in comparative example 2. Other conditions were the same as in comparative example 2. In comparative example 3, the average particle diameter of the calcined powder was 321 nm. The average grain diameter of the grains 14 is 387 nm.

In example 1, the proportion of the number of core-shell particles 30 in the dielectric layer 11 to the entire crystal grains 14 was 15.9%. In example 2, the ratio was 23.7%. In example 3, the ratio was 2.7%. In example 4, the ratio was 8.5%. In example 5, the ratio was 21.4%. In example 6, the ratio was 0.6%. In comparative examples 1 to 3, the core-shell particles 30 were not formed. Namely, in comparative examples 1 to 3, the ratio was 0%. Table 1 shows the results.

[ Table 1]

(life measuring test) next, the life was measured for each of examples 1 to 6 and comparative examples 1 to 3. The sample was determined to be good ". smallcircle" when the life was 800 minutes or more under the acceleration conditions of 150 ℃ and-240V. When the life was less than 800 minutes, the sample was determined to be poor "x".

In the measurement of the lifetime, comparative examples 1 to 3 were determined to be poor "x". This is considered because the core-shell particles 30 are not contained in the dielectric layer 11, and oxygen vacancies are not trapped. On the other hand, examples 1 to 6 were determined to be good "o" in the measurement of the lifetime. This is considered to be because the core-shell particles 30 are contained in the dielectric layer 11, trapping oxygen vacancies.

It was confirmed that the lifetime becomes longer as the ratio of the number of core-shell particles 30 to the total crystal grains 14 in the dielectric layer 11 increases. It was confirmed that the ratio is preferably 2% or more in order to extend the life to 1000 minutes or more.

(rate of temperature change) next, the rate of temperature change was measured for each of examples 1 to 6 and comparative examples 1 to 3. The rate of change in capacity at 125 ℃ was measured relative to the standard capacity at 25 ℃. When the capacity change rate was-33%, the sample was judged to be good.

The capacity change rate of examples 2 and 5 was less than-33%. But examples 1, 3, 4 and 6 were judged to be good. This is considered to be because the proportion of the core-shell particles 30 in the dielectric layer 11 is 20% or less. Even if the capacity change rate is less than-33%, the sample can be used as a product when the upper limit of the temperature compensation range is lowered from 125 ℃ to 105 ℃ or 85 ℃.

From the results, it was confirmed that the proportion of the core-shell particles 30 in the dielectric layer 11 is preferably 2% or more and 20% or less. It was confirmed that the proportion of the core-shell particles 30 in the dielectric layer 11 is preferably 5% to 16% from the viewpoint of achieving a more preferable rate of change in capacity and a more preferable lifetime characteristic.

Example 7 in example 7, rare earth elements other than Dy were added. In example 7, each material was weighed so as to be converted into BaTiO₃When the amount of the oxides of Ba and Ti is 100 mol%, when converted to Ho₂O₃When the amount of Ho oxide is 1.75 mol%, when converted to MgO, the amount of Mg oxide is 0.15 mol%, when converted to V₂O₅When the amount of V oxide is 0.05 mol%, it is converted to SiO₂When the amount of Si oxide is 1.50 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In example 7, the average particle size of the calcined powder was 115 nm. The average grain diameter of the sintered structure was 317 nm. Other conditions were the same as in example 1.

(example 8) in example 8, each material was weighed so as to be converted into BaTiO₃When the amount of the oxides of Ba and Ti is 100 mol%, when converted to Ho₂O₃When the amount of Ho oxide is 2.00 mol%, when converted to MgO, the amount of Mg oxide is 0.15 mol%, when converted to V₂O₅When the amount of V oxide is 0.05 mol%, it is converted to SiO₂When the amount of Si oxide is 1.50 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In example 8, the average particle diameter of the calcined powder was 115 nm. The average grain diameter of the sintered structure was 422 nm. Other conditions were the same as in example 1.

(example 9) in example 9, each material was weighed so as to be converted into BaTiO₃When the amount of the oxides of Ba and Ti is 100 mol%, when converted to Ho₂O₃When the content of Ho oxide is 2.50 mol%, the content is expressed as MnO₂When the amount of the Mn oxide is 0.15 mol%, it is converted to V₂O₅When the amount of V oxide is 0.05 mol%, it is converted to SiO₂When the amount of Si oxide is 1.50 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In example 8, the average particle diameter of the calcined powder was 115 nm. The average grain diameter of the sintered structure was 342 nm. Other conditions were the same as in example 1.

(example 10) in example 10, each material was weighed so as to be converted into BaTiO₃When calculated as Ho, the amount of the oxides of Ba and Ti is 100 mol%₂O₃When the amount of Ho oxide is 2.50 mol%, when converted to ZrO₂When calculated as V, the amount of Zr oxide is 0.15 mol%₂O₅When the amount of V oxide is 0.05 mol%, it is converted to SiO₂When the amount of Si oxide is 1.50 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In example 10, the average particle size of the calcined powder was 115 nm. The average grain diameter of the sintered structure was 252 nm. Other conditions were the same as in example 1.

(example 11) in example 11, each material was weighed so as to be converted into BaTiO₃When calculated as Ho, the amount of the oxides of Ba and Ti is 100 mol%₂O₃When the amount of Ho oxide was 2.50 mol%, when converted to MgO, the amount of Mg oxide was 0.15 mol%, when converted to Cr₂O₃When the amount of Cr oxide is 0.05 mol%, the amount is converted to SiO₂When the amount of Si oxide is 1.50 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In example 11, the average particle size of the calcined powder was 115 nm. The average grain diameter of the sintered structure was 316 nm. Other conditions were the same as in example 1.

(example 12) in example 12, each material was weighed so as to be converted into BaTiO₃When the amount of the oxide of Ba and Ti is 100 mol%, the amount is converted to Y₂O₃When calculated as Ho, the amount of Y oxide is 1.75 mol%₂O₃When the amount of Ho oxide is 1.75 mol%, when converted to MgO, the amount of Mg oxide is 0.15 mol%, when converted to V₂O₅When the amount of V oxide is 0.05 mol%, it is converted to SiO₂When the amount of Si oxide is 1.50 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In example 12, the average particle diameter of the calcined powder was 127 nm. The average grain diameter of the sintered structure was 328 nm. Other conditions were the same as in example 1.

(example 13) in example 13, each material was weighed so as to be converted into BaTiO₃When calculated as Y, the amount of the oxides of Ba and Ti is 100 mol%₂O₃When calculated as Ho, the amount of Y oxide is 1.00 mol%₂O₃When the amount of Ho oxide is 1.75 mol%, when converted to MgO, the amount of Mg oxide is 0.15 mol%, when converted to V₂O₅When the amount of V oxide is 0.05 mol%, it is converted to SiO₂When the amount of Si oxide is 1.50 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In example 13, the average particle diameter of the calcined powder was 127 nm. The average grain diameter of the sintered structure was 387 nm. Other conditions were the same as in example 1.

(example 14) in example 14, each material was weighed so as to be converted into BaTiO₃When calculated as Ho, the amount of the oxides of Ba and Ti is 100 mol%₂O₃When the content of Ho oxide is 2.50 mol%, the content is expressed as MnO₂When the amount of the Mn oxide is 0.50 mol%, it is converted to V₂O₅When the amount of V oxide is 0.05 mol%, it is converted to SiO₂When the amount of Si oxide is 1.20 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In example 14, the average particle size of the calcined powder was 115 nm. The average grain diameter of the sintered structure was 284 nm. Other conditions were the same as in example 1.

(example 15) in example 15, each material was weighed so as to be converted into BaTiO₃When calculated as Ho, the amount of the oxides of Ba and Ti is 100 mol%₂O₃When the content of Ho oxide is 2.50 mol%, the content is expressed as MnO₂When the amount of the Mn oxide is 1.50 mol%, it is converted to V₂O₅When the amount of V oxide is 0.05 mol%, it is converted to SiO₂In this case, the amount of Si oxide was 1.00 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In example 15, the average particle size of the calcined powder was 115 nm. The average grain diameter of the sintered structure was 237 nm. Other conditions were the same as in example 1.

(example 16) in example 16, each material was weighed so thatWhen converted to BaTiO₃When calculated as Ho, the amount of the oxides of Ba and Ti is 100 mol%₂O₃When the amount of Ho oxide is 2.50 mol%, when converted to MgO, the amount of Mg oxide is 2.00 mol%, when converted to V₂O₅When the amount of V oxide is 0.05 mol%, it is converted to SiO₂When the amount of Si oxide is 1.20 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In example 16, the average particle diameter of the calcined powder was 115 nm. The average grain diameter of the sintered structure was 251 nm. Other conditions were the same as in example 1.

(comparative example 4) in comparative example 4, each material was weighed so that it was converted into BaTiO₃When calculated as Ho, the amount of the oxides of Ba and Ti is 100 mol%₂O₃When the content of Ho oxide is 3.50 mol%, the content is expressed as MnO₂When the amount of the Mn oxide is 0.15 mol%, it is converted to V₂O₅When the amount of V oxide is 0.05 mol%, it is converted to SiO₂When the amount of Si oxide is 1.70 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In comparative example 4, the step of maintaining the temperature at 880 ℃ for 20 minutes was not performed. Cooling is performed from the highest temperature in the firing step. Other conditions were the same as in example 1. In comparative example 4, the average particle diameter of the calcined powder was 253 nm. The average grain diameter of the sintered structure was 302 nm.

(comparative example 5) in comparative example 5, each material was weighed so that it was converted to BaTiO₃When calculated as Ho, the amount of the oxides of Ba and Ti is 100 mol%₂O₃When the amount of Ho oxide is 2.50 mol%, when converted to ZrO₂When calculated as V, the amount of Zr oxide is 0.10 mol%₂O₅When the amount of V oxide is 0.05 mol%, it is converted to SiO₂When the amount of Si oxide is 1.90 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In comparative example 5, the step of maintaining the temperature at 880 ℃ for 20 minutes was not performed. Cooling is performed from the highest temperature in the firing step. Other conditions were the same as in example 1. In comparative example 5, calcinationThe average particle diameter of the fired powder was 253 nm. The average grain diameter of the sintered structure was 284 nm.

(comparative example 6) in comparative example 6, each material was weighed so that it was converted into BaTiO₃When calculated as Y, the amount of the oxides of Ba and Ti is 100 mol%₂O₃When calculated as Ho, the amount of Y oxide is 1.75 mol%₂O₃When the amount of Ho oxide is 1.75 mol%, when converted to MgO, the amount of Mg oxide is 0.075 mol%, when converted to V₂O₅When the amount of V oxide is 0.05 mol%, it is converted to SiO₂When the amount of Si oxide is 1.80 mol%. The materials were wet mixed and pulverized into a mixture in a ball mill for 15 to 24 hours. In comparative example 6, the step of maintaining the temperature at 880 ℃ for 20 minutes was not performed. Cooling is performed from the highest temperature in the firing step. Other conditions were the same as in example 1. In comparative example 6, the average particle diameter of the calcined powder was 252 nm. The average grain diameter of the sintered structure was 279 nm.

In example 7, the proportion of core-shell particles 30 to the entire crystal grains 14 in the dielectric layer 11 was 9.7%. In example 8, the ratio was 18.1%. In example 9, the ratio was 10.2%. In example 10, the ratio was 3.2%. In example 11, the ratio was 7.4%. In example 12, the ratio was 8.5%. In example 13, the ratio was 17.5%. In example 14, the ratio was 8.1%. In example 15, the ratio was 2.2%. In example 16, the ratio was 2.9%. In comparative examples 4 to 6, no core-shell particles 30 were formed. That is, in comparative examples 4 to 6, the ratio was 0%. Tables 2 and 3 show the results.

[ Table 2]

[ Table 3]

(life measuring test) next, the life was measured for each of examples 7 to 16 and comparative examples 4 to 6. When the lifetime was 800 minutes or more under the acceleration conditions of 150 ℃ and-240V, the sample was judged as good ". smallcircle". When the life was less than 800 minutes, the sample was judged to be poor "x".

In the life measurement test, comparative examples 4 to 6 were judged as poor "x". This is considered because the core-shell particles 30 are not contained in the dielectric layer 11, and oxygen vacancies are not trapped. On the other hand, examples 7 to 16 were judged as good "o" in the life measurement test. This is considered to be because the core-shell particles 30 are contained in the dielectric layer 11, trapping oxygen vacancies.

It was confirmed that as the ratio of the number of core-shell particles 30 to the total crystal grains 14 in the dielectric layer 11 increases, the lifetime becomes longer. It was confirmed that the ratio is preferably 2% or more in order to extend the life to 1000 minutes or more.

(rate of temperature change) next, the rate of temperature change was measured for each of examples 7 to 16 and comparative examples 4 to 6. The rate of change in capacity at 125 ℃ was measured relative to the standard capacity at 25 ℃. When the capacity change rate was-33%, the sample was judged to be good.

Examples 7 to 16 were judged to be good. This is considered to be because the proportion of the core-shell particles 30 in the dielectric layer 11 is 20% or less.

From the above results, it is understood that the proportion of the core-shell particles 30 in the dielectric layer 11 is preferably 2% to 20%. Also, the proportion of the core-shell particles 30 in the dielectric layer 11 is preferably 5% to 16% from the viewpoint of achieving a more preferable rate of capacity change and a more preferable lifetime characteristic.

It is also found that the amount of the ceramic as the main component in the dielectric layer 11 is 100mol% and oxide of Re is converted to Re₂O₃When it is preferable to add 1.75 mol% to 3.50 mol% of Re oxide to the dielectric layer 11. The amount of the ceramic as the main component of the dielectric layer 11 is 100 mol%, and oxides of Mg, V, Mn, Zr and Cr are converted to MgO and MnO₂、ZrO₂、V₂O₅And Cr₂O₃When it is preferable to add oxides of Mg, V, Mn, Zr, and Cr to the dielectric layer 11 in a total amount of 0.02 mol% to 2.05 mol%. The amount of the ceramic as the main component of the dielectric layer 11 was 100 mol% and the oxide content of Si was converted to SiO₂In this case, it is preferable to add 0.25 mol% to 2.50 mol% of an oxide of Si to the dielectric layer 11.

Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereto without departing from the spirit and scope of the invention.