WO2024185660A1

WO2024185660A1 - Multilayer electronic component and method for producing same

Info

Publication number: WO2024185660A1
Application number: PCT/JP2024/007665
Authority: WO
Inventors: 大輔福田; 祐太岡▲崎▼; 夢香妹尾
Original assignee: 京セラ株式会社
Priority date: 2023-03-09
Filing date: 2024-03-01
Publication date: 2024-09-12

Abstract

Disclosed is a multilayer electronic component wherein a multilayer element comprises effective parts and internal electrodes, which are alternately stacked upon each other. A side margin part is superposed on the side surface of the multilayer element, the side surface extending along the stacking direction. The effective parts and the side margin part are both configured from a polycrystalline ceramic. The polycrystalline ceramic contains BT-based particles that are formed of a barium titanate having a perovskite structure represented by composition formula ABO₃. The A site of the BT-based particles contains Ba. The B site of the BT-based particles contains Ti. With respect to the BT-based particles, if the value obtained by dividing the amount of substance of the elements in the A site by the amount of substance of the elements in the B site is defined as an A/B ratio, the A/B ratio of the side margin part is smaller than the A/B ratio of the effective parts.

Description

Multilayer electronic component and its manufacturing method

This disclosure relates to a multilayer electronic component and a manufacturing method thereof. The multilayer electronic component is, for example, a multilayer ceramic capacitor.

A multilayer ceramic capacitor having a plurality of dielectric layers and a plurality of internal electrodes alternately stacked is known (for example, see Patent Document 1 below). In Patent Document 1, the dielectric layers are mainly composed of BaTiO ₃ crystal particles (hereinafter, sometimes referred to as "BT particles") and (Ba _1-x Ca _x )TiO ₃ crystal particles (hereinafter, sometimes referred to as "BCT particles") in which part of the Ba in BaTiO ₃ is replaced with Ca. Patent Document 1 proposes that when the total amount of Ba and Ca is A moles and the total amount of Ti is B moles, A/B≧1.003. The contents of Patent Document 1 may be incorporated by reference in this disclosure.

JP 2006-156450 A

A multilayer electronic component according to an embodiment of the present disclosure includes a laminate and a side margin portion. The laminate includes effective portions and internal electrodes that are alternately stacked. The side margin portion overlaps a side surface of the laminate along the stacking direction. The effective portion and the side margin portion are both made of polycrystalline ceramics. The polycrystalline ceramics include barium titanate-based BT-based particles having a perovskite structure represented by a composition formula _ABO3 . The A site of the BT-based particles includes Ba. The B site of the BT-based particles includes Ti. The value obtained by dividing the amount of substance of the element at the A site in the BT-based particles by the amount of substance of the element at the B site is referred to as the A/B ratio. In this case, the A/B ratio of the side margin portion is smaller than the A/B ratio of the effective portion.

A method for manufacturing a multilayer electronic component according to an aspect of the present disclosure includes a molding step of obtaining a molded body and a firing step of firing the molded body. The molded body includes a laminate and a second ceramic green sheet. The laminate includes first ceramic green sheets and a conductive paste that are alternately stacked. The second ceramic green sheet overlaps a side of the laminate along the stacking direction. The first ceramic green sheet and the second ceramic green sheet both include a barium titanate-based BT-based powder having a perovskite structure represented by a composition formula _ABO3 . The A site of the BT-based powder includes Ba. The B site of the BT-based powder includes Ti. The value obtained by dividing the amount of substance of the element at the A site in the BT-based powder by the amount of substance of the element at the B site is referred to as the A/B ratio. In this case, the A/B ratio of the second ceramic green sheet is smaller than the A/B ratio of the first ceramic green sheet.

1 is a perspective view showing a multilayer ceramic capacitor according to an embodiment; FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 2 is a cross-sectional view taken along line III-III in FIG. 2 is a flowchart showing the steps of a method for manufacturing the capacitor of FIG. 1 . 1 is a table showing specifications of capacitors according to examples and comparative examples. 13 is a table showing specifications of a capacitor according to another embodiment.

Below, an embodiment of the present disclosure will be described with reference to the drawings. Note that the drawings used in the following description are schematic. Therefore, for example, the dimensional ratios in the drawings do not necessarily match those in reality. Furthermore, the dimensional ratios may not match between drawings. Certain shapes and/or dimensions may be exaggerated, and details may be omitted. However, the above does not deny that the actual shapes and/or dimensions may be as shown in the drawings, or that features of shapes and/or dimensions may be extracted from the drawings.

(Overview of the embodiment)
Fig. 1 is a perspective view showing a capacitor 1 (an example of a multilayer electronic component) according to an embodiment. For convenience, a Cartesian coordinate system xyz is attached to Fig. 1 and other figures described later. The capacitor 1 may be used with either side being the upper or lower. However, in the description of the embodiment, for convenience, the +z side may be regarded as the upper side, and terms such as the upper surface and the lower surface may be used.

The capacitor 1 has, for example, a roughly rectangular parallelepiped body 3 and a pair of external electrodes 5 located at both ends of the body 3.

FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. The main body 3 has effective portions 7 and internal electrodes 9 that overlap each other. More specifically, in the illustrated example, an internal electrode 9 connected to one external electrode 5 faces an internal electrode 9 connected to the other external electrode 5 via the effective portion 7. The effective portion 7 is a dielectric. The dielectric is made of polycrystalline ceramics. With this configuration, a multilayer ceramic capacitor is realized. The portion made up of the multiple effective portions 7 and multiple internal electrodes 9 is referred to as the laminate 11.

FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 3 also shows an enlarged view of a portion of the dielectric that constitutes the main body 3. The main body 3 has a side margin 13 that overlaps the side surface of the laminate 11 along the stacking direction. The side margin 13 is made of polycrystalline ceramics (dielectric). The side margin 13 contributes, for example, to insulating the internal electrode 9 from the outside and/or improving the strength of the main body 3.

3, the dielectric has, for example, crystal grains (17) and grain boundary layers 19 between the crystal grains. In both the effective portion 7 and the side margin portion 13, the crystal grains are composed of barium titanate (BaTiO ₃ )-based crystal grains (hereinafter sometimes referred to as "BT-based grains 17").

The BT-based particles 17 have a perovskite structure and are represented by the composition formula _ABO3 . The main element in the A site is Ba. For example, Ba occupies 70 mol % or more of the A site. The main element in the B site is Ti. For example, Ti occupies 90 mol % or more of the B site. In other words, the BT-based particles 17 are a material in which part of Ba is not substituted or is substituted with other elements in _BaTiO3 , and part of Ti is not substituted or is substituted with other elements.

The O in _ABO3 is oxygen. However, a part of the O may be substituted. From this, the O in _ABO3 may be regarded as indicating an O site, not oxygen. However, in the description of the embodiment, unless otherwise specified, or unless a contradiction occurs, the O may be regarded as indicating oxygen.

Elements used to partially replace Ba include, for example, elements that belong to Group 2 like Ba (e.g., Ca, Sr, and Mg). Elements used to partially replace Ti include, for example, elements that belong to Group 4 like Ti (e.g., Zr and Hf).

In the BT-based particles 17, the amount of substance of an element contained in the A site is A moles. The amount of substance of an element contained in the B site is B moles. The value (A/B) obtained by dividing the former by the latter is called the A/B ratio. From the composition formula _ABO3 , the A/B ratio is 1, but the BT-based particles 17 can have an A/B ratio other than 1. From another perspective, for example, in a part of the BT-based particles 17, a perovskite structure strictly conforming to theory is not formed. The A/B ratio of the side margin portion 13 is smaller than the A/B ratio of the effective portion 7.

This improves, for example, the thermal shock resistance of the side margin portion 13. For example, when the temperature of the capacitor 1 rises, the likelihood of cracks occurring in the side margin portion 13 is reduced. The reasons for this are, for example, as follows.

In manufacturing the main body 3, for example, a ceramic green sheet that will become the active portion 7 and a conductive paste that will become the internal electrode 9 are laminated to create the laminate 11 before firing. Next, a ceramic green sheet that will become the side margin portion 13 is attached to the side surface of the laminate 11 before firing to form a molded body. The molded body is then fired.

In the technology of the comparative example, the effective portion 7 is easier to sinter than the side margin portion 13 during firing. Therefore, for example, if firing conditions are set to match the effective portion 7, the side margin portion 13 may not sinter sufficiently, resulting in a decrease in the strength of the side margin portion 13. The reason why the effective portion 7 is easier to sinter than the side margin portion 13 is, for example, that the conductive paste that becomes the internal electrode 9 shrinks, causing stress to be applied to the effective portion 7.

Here, when the A/B ratio is made small, the ceramic material before firing becomes easier to sinter. Therefore, when the A/B ratio of the side margin portion 13 is made small compared to the A/B ratio of the effective portion 7, the degree of sintering of the side margin portion 13 and the effective portion 7 becomes closer. As a result, for example, even under firing conditions that are suited to the effective portion 7, the side margin portion 13 is sufficiently sintered, and the strength of the side margin portion 13 is improved.

In addition, from another perspective, the above means that the firing conditions for the effective portion 7 can be made suitable for the effective portion 7. As a result, for example, it is possible to improve the characteristics related to the temperature dependency of capacitance and improve the insulation of the effective portion 7 while maintaining the thermal shock resistance of the side margin portion 13.

If the thermal shock resistance of the side margin portion 13 is improved, for example, it is possible to make the side margin portion 13 thinner while still maintaining a certain level of thermal shock resistance of the main body portion 3. As a result, it becomes easier to miniaturize the capacitor 1. From another perspective, it is possible to increase the volume of the laminate 11 relative to the size of the capacitor 1, thereby increasing the capacitance.

The above is an overview of the capacitor 1 according to the embodiment. The embodiment will be described below in the following order.
Chapter A First Embodiment 1. Capacitor Structure (FIGS. 1 to 3)
1.1. Structure of the illustrated example 1.2. Structure of examples other than the illustrated example 2. Dielectric 2.1. Dielectrics in general 2.2. Examples of component ratios, etc. 2.3. A/B ratio 2.3.1. A/B ratio in general 2.3.2. A/B ratio of side margin portion 2.3.3. A/B ratio of cover portion 3. Manufacturing method (Fig. 4)
3.1. Manufacturing procedure 3.2. Manufacturing method of dielectric 3.3. Setting method of A/B ratio 4. Example (FIGS. 5 and 6)
5. Summary of the First Embodiment Chapter B. Other Embodiments

The first embodiment in Chapter A and the other embodiments in Chapter B differ from each other in the specific composition of the barium titanate-based BT particles 17. All other matters are basically similar to each other. Therefore, for the embodiments described later, basically only the differences from the previously described embodiments will be described. Matters that are not specifically mentioned may be considered to be the same as the previously described embodiments or may be inferred from the previously described embodiments.

<Chapter A First Embodiment>
(1. Capacitor Structure)
(1.1. Structure of the illustrated example)
As can be understood from the outline of the embodiment described above, the structure of the capacitor 1 may have various configurations as long as it has the laminate 11 and the side margin portion 13. However, in explaining the embodiment, for convenience, the explanation may be given on the premise of the configuration illustrated in Figures 1 to 3 unless otherwise specified. The structure of the capacitor 1 illustrated in Figures 1 to 3 is as follows.

In addition to the configuration already described (laminated body 11, side margin portion 13, and external electrode 5), the capacitor 1 has a pair of cover portions 15 (reference numbers in Figs. 2 and 3) that overlap the upper and lower surfaces of the laminate 11. The cover portions 15 are made of, for example, BT-based polycrystalline ceramics, similar to the active portion 7 and side margin portion 13. The cover portions 15 contribute to insulating the internal electrode 9 from the outside and/or improving the strength of the main body portion 3.

As already mentioned, the shape of the main body 3 (or the entire capacitor 1; the same applies hereinafter in this paragraph) is roughly rectangular. For example, the height (length in the z direction) of this rectangular parallelepiped may be equal to (as in the illustrated example) or smaller than the width (length in the y direction). The length (x direction) of the rectangular parallelepiped is, for example, greater than the width. The dimensions of the main body 3 are arbitrary. Examples of relatively small dimensions include a length of 0.4 mm or more and 3.2 mm or less, and a width and height of 0.2 mm or more and 2.5 mm or less.

The effective portion 7 is basically a layer having a constant thickness (at least between the internal electrodes 9). The thickness of the effective portion 7 may be set appropriately depending on the characteristics required of the capacitor 1. Examples of relatively thin thicknesses include a thickness of 3 μm or less or 1 μm or less. The planar shape of the effective portion 7 is arbitrary, and is rectangular in the illustrated example. The multiple effective portions 7 have, for example, the same shape, size, and material as each other. The number of layers of the effective portions 7 (internal electrodes 9) is arbitrary.

The internal electrode 9 is a layer having a certain thickness. The thickness of the internal electrode 9 is arbitrary, and is, for example, thinner than the thickness of the effective portion 7. The internal electrode 9 overlaps the entire surface of the effective portion 7, except for the external electrode 5 side (-x side or +x side) to which it is not connected. Therefore, the outer edge of the internal electrode 9 is exposed to the side of the laminate 11 from three sides (three sides) excluding the -x side or +x side. In other words, the planar shape of the internal electrode 9 is a rectangular shape obtained by excluding the area on the -x side or +x side in the planar shape of the effective portion 7. The width (length in the x direction) of the above-mentioned area on the -x side or +x side is arbitrary. The material of the internal electrode 9 is, for example, a base metal. Examples of base metals include Ni and Cu. The multiple internal electrodes 9 have, for example, the same shape, size, and material as each other.

The side margin portion 13 is generally a layer having a constant thickness. However, the corners on the outside of the main body portion 3 may be rounded. The thickness of the side margin portion 13 is arbitrary, and may be thicker (as in the illustrated example), equal to, or thinner than the thickness of the effective portion 7. An example of a relatively thin thickness is 30 μm or less. The side margin portion 13 covers not only the -y or +y side of the laminate 11, but also the side of the upper and lower cover portions 15. In other words, the side margin portion 13 constitutes the entire -y or +y side of the main body portion 3. A pair of side margin portions 13 have, for example, the same shape, size, and material as each other.

The cover portion 15 is generally in the form of a layer having a constant thickness. The thickness of the cover portion 15 is arbitrary, and may be, for example, thicker (in the illustrated example), equal to, or thinner than the thickness of the active portion 7, or thicker (in the illustrated example), equal to, or thinner than the thickness of the side margin portion 13. An example of a relatively thin thickness is 30 μm or less. The cover portion 15 covers the entire upper or lower surface of the laminate 11. A pair of cover portions 15 have, for example, the same shape, size, and material as each other.

The top or bottom layer of the laminate 11 may be the internal electrode 9 (in the illustrated example) or the active portion 7. In other words, the cover portion 15 may overlap the internal electrode 9 (in the illustrated example) or the active portion 7.

The external electrode 5 is generally a layer covering the longitudinal end of the main body 3 across five faces of the rectangular parallelepiped. The external electrode 5 is connected to the edge of the internal electrode 9 that is exposed from the side surface on the -x side or +x side of the laminate 11. The thickness of the external electrode 5 is arbitrary. The external electrode 5 may be formed, for example, by stacking layers made of different materials. The external electrode 5 is joined to a pad on a circuit board or the like, for example, by a conductive bonding material such as solder. In this way, the capacitor 1 is mounted on the circuit board or the like.

(1.2. Structure of Examples Other Than the Examples Shown)
An example of the structure of the capacitor 1 other than the example shown in the drawing will be given.

The capacitor 1 may have an exterior resin that covers the entire structure shown in the figure, and a lead wire that is connected to the external electrode 5 and extends from the exterior resin. Also, a groove extending in the z direction may be formed on the side surface of the main body 3 in the y direction and/or x direction, and a part or all of the external electrode may be formed by a metal filled or deposited in this groove. As described above, the configuration for mounting the capacitor 1 is arbitrary. Also, as can be understood from the above, the side surface of the laminate 11 covered by the side margin portion 13 does not have to be a side surface along the longitudinal direction of the laminate 11, and does not have to be a side surface on which an external electrode is not provided.

The capacitor 1 does not have to have a cover portion 15. For example, the top or bottom internal electrode 9 may be covered by the effective portion 7. In this case, however, the effective portion 7 covering the top or bottom internal electrode 9 may be considered to be a cover portion 15 made of the same material as the effective portion 7 between the internal electrodes 9.

The internal electrodes 9 connected to different external electrodes 5 do not have to face each other. That is, the capacitor 1 does not have to have a plurality of parallel plate capacitors connected in parallel to each other. For example, an internal electrode 9 connected to one external electrode 5 and an internal electrode 9 connected to the other external electrode 5 may be provided in different regions of the same layer. Then, an internal electrode 9 may be provided that faces both of these internal electrodes 9 and is not connected to either external electrode 5. In this way, the capacitor 1 may include two parallel plate capacitors connected in series. In the above example, the number of parallel plate capacitors connected in series is two, but three or more parallel plate capacitors may be connected in series.

Furthermore, the internal electrodes 9 connected to different external electrodes 5 may be arranged to face each other in alternating pairs, rather than one at a time. In this case, for example, the thickness of the effective portion 7 between the internal electrodes 9 that are connected to the same external electrode 5 and face each other may be thinner than the thickness of the effective portion 7 between the internal electrodes 9 that are connected to different external electrodes 5 and face each other. As can be understood from this, the multiple effective portions 7 do not have to have the same shape and size.

The internal electrode 9 does not have to be exposed from the side surface (the -y side or the +y side side) over the entire length (the entire length in the x direction) of the side surface covered by the side margin portion 13 of the laminate 11. For example, only a portion of the internal electrode 9 may be exposed from the side surface. Also, as can be understood from the various aspects of the external electrode 5 described above, the entire internal electrode 9 does not have to be exposed from the side surface.

(2. Dielectrics)
(2.1. Dielectrics in General)
The crystal grains of the dielectric material constituting the effective portion 7, the side margin portion 13, and the cover portion 15 are BT-based grains 17. In the first embodiment, the BT-based grains 17 are composed of the following two types of crystal grains.
_BaTiO3 crystal particles (hereinafter sometimes referred to as "BT particles")
Ba1 _- _xCaxTiO3 _crystal particles (hereinafter sometimes referred to as "BCT particles")
Incidentally, Ba, Ca, Ti and O may be referred to as "major component elements".

BT particles have a higher dielectric constant than, for example, BCT particles. BCT particles are advantageous in reducing the temperature dependency of the dielectric constant and/or reducing the DC bias characteristics (change (reduction) in effective capacitance due to application of a direct current voltage) compared to, for example, BT particles. Therefore, by combining the two, it is possible to obtain the advantages of both.

The dielectric may contain appropriate elements in addition to the main component elements. For example, the dielectric may contain Mg, rare earth elements (hereinafter sometimes referred to as "RE"), Mn, Cr and/or V. The RE contained in the dielectric may be, for example, one or more selected from La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu and Sc. In the following, Mg, RE, Mn, Cr and V may be referred to as the "first minor component element" for convenience.

The elements of the first minor component are added, for example, as a mixed powder of dielectrics to the powder that will become the BT-based particles 17. And, Mg and RE, for example, contribute to the formation of a core-shell structure. The core-shell structure is a structure in which the above elements (Mg and RE) are unevenly distributed on the surface side of the crystal particles (here, BT particles and BCT particles) rather than the center. The core-shell structure, for example, reduces the temperature dependence of the relative dielectric constant and/or reduces the DC bias characteristics. Mn, Cr, and V, for example, compensate for oxygen defects in the crystal particles and contribute to improving the insulation properties and high-temperature load life.

For example, a portion of the elements of the first subcomponent is dissolved in the BT-based particles 17, and the other portion is located in the grain boundary layer 19. When these elements are present in the grain boundary, they exist, for example, as amorphous matter. Note that, for each element related to the first subcomponent, either the amount dissolved in the BT-based particles 17 or the amount located in the grain boundary layer 19 may be greater, and for example, the former may be greater.

As can be understood from the above, for example, even if expressed as BT particles made of BaTiO ₃ or BCT particles made of Ba _1-x Ca _x TiO ₃ , each particle may contain elements of the subcomponent (first subcomponent or other subcomponent) in solid solution. In this case, it is acceptable that a part of the crystal structure is formed as if Ba or Ti is replaced by the element of the subcomponent.

As described later, the amount of the subcomponent element is relatively small. Therefore, for example, even if Ba or Ti is replaced by the subcomponent element, the effect of the subcomponent may be ignored in the explanation (described later) of the amount (mass % and mol % etc.) of the BT-based particles 17 (BT particles or BCT particles). For example, the mass % or mol % of the BT-based particles 17 (for example, the % of the element in the BT-based particles 17 or the % of the BT-based particles 17 in the dielectric) may be the value before the subcomponent element is solid-dissolved in the BT-based particles 17. However, since the amount of the subcomponent element is relatively small, the mass % or mol % of the BT-based particles 17 may be considered to be the value after solid solution.

Also, crystal particles in which the main component element is largely replaced by the subcomponent element may be regarded as a type of BT-based particle 17 (or a non-BT-based crystal particle) different from BT particles and BCT particles. For example, when the amount of replacement (not simply the amount of solid solution) is 1.0 mol % or more or 0.5 mol % or more, it may be regarded as another type of BT-based particle 17. Conversely, for example, the amount of Ba replacement and the amount of Ti replacement of BT particles may be less than 0.5 mol %. Note that, for convenience, in the explanation of the first embodiment, the explanation may be made on the assumption that the crystal particles of the dielectric constituting the effective portion 7, the side margin portion 13, and the cover portion 15 are only BT particles and BCT particles, unless otherwise specified.

The dielectric may contain minor components (hereinafter sometimes referred to as "impurities") other than the main component element and the first minor component element. Impurities may include, for example, those derived from glass powder mixed in during the manufacturing process of the dielectric (e.g., aluminum).

The dielectrics constituting the effective portion 7, the side margin portion 13, and the cover portion 15 may be the same or different in terms of properties other than the A/B ratio. However, for the sake of convenience, in the description of the embodiment, unless otherwise specified, properties other than the A/B ratio are assumed to be the same for each portion.

(2.2. Examples of component ratios, etc.)
Various values such as mass % and mol % of each component may be set appropriately, and known values disclosed in, for example, Patent Document 1 may be referred to. Examples of value ranges are shown below. Just to be sure, the conditions related to the ranges exemplified below do not have to be satisfied. The values shown below are, for example, values determined from the weighing of raw materials in the manufacturing process. However, the values below may be analytical values after manufacturing.

The BT-based particles 17 are as follows.
(a1) Amount of BT-based particles 17 (a1-1) 90% by mass or more, 95% by mass or more, or 98% by mass or more of the dielectric (a1-2) 95% by mass or more, 98% by mass or more, or 100% by mass (excluding minor errors) of all crystal particles (not necessarily BT-based) contained in the dielectric, and/or 95 mol % or more, 98 mol % or more, or 100 mol % or more (excluding minor errors)
(a2) Total amount of BT particles and BCT particles: 95% by mass or more, 98% by mass or more, or 100% by mass (minor errors excluded) of the BT-based particles 17, and/or 95 mol % or more, 98 mol % or more, or 100 mol % or more (minor errors excluded)
(a3) Relationship between the amount of BT particles and the amount of BCT particles (a3-1) Area ratio of BT particles to BCT particles in a cross section or surface of a dielectric (BT/BCT): 0.1 or more and 3.0 or less, or 0.3 or more and 2.0 or less (a3-2) Molar ratio or mass ratio of BCT particles to BT particles (BCT/BT): 0.05 or more and 20.00 or less, 0.25 or more and 4.00 or less, or 0.95 or more and 1.05 or less (a4) Relationship between the amount of Ba and the amount of Ca in BCT particles (a4-1) x in Ba1 _-xCax _: 0.01 or more and 0.20 or less, or 0.02 or more and 0.07 or less (a4-2) Ba is 70 mol % or more or 80 mol % or more of A site (a5) Amount of Ti in BT-based particles 17 (BT and BCT): 90 mol % or more, 95 mol % or more, or 100 mol % of the B site (minor errors excluded)
(a6) Amount of O (oxygen) in BT-based particles 17 (BT and BCT): 90 mol % or more, 95 mol % or more, or 100 mol % of O sites (minor errors excluded)
(a7) Diameter of BT-based particles 17 (BT and BCT): Average particle size: 0.10 μm or more and 0.80 μm or less, or 0.15 μm or more and 0.40 μm or less

When the above condition (a1) is satisfied, for example, the properties of barium titanate-based crystals are easily exhibited. As a result, for example, the effect of varying the A/B ratio according to the portion of the capacitor 1, as described in the outline of the embodiment, is easily exhibited. In addition, for example, the effect of using BT particles and BCT particles in combination (reducing the temperature dependence of the dielectric constant and the DC bias characteristics while maintaining the dielectric constant) is easily exhibited.

When the above conditions (a2) and (a3) are met, for example, a certain amount of BCT particles is ensured, and the effect of reducing the temperature dependency of the dielectric constant and the DC bias characteristics is easily achieved. Furthermore, when the condition (a4-1) is met, the phase transition point near room temperature shifts to a sufficiently low temperature side. As a result, for example, the effect of reducing the temperature dependency of the dielectric constant and the DC bias characteristics is easily achieved.

When the above conditions (a4-2), (a5), and (a6) are satisfied, the properties of barium titanate (BT), for example, are easily maintained. As a result, for example, it is easy to increase the relative dielectric constant.

When the above condition (a7) is satisfied, for example, the particle size is relatively small, so that it is easy to make the dielectric layer (e.g., the effective portion 7) thin. In addition, since a certain degree of particle size is ensured, it is easy to ensure the relative dielectric constant.

The elements of the first subcomponent are as follows. In the following, the parts by mass are shown when the BT-based particles 17 are taken as 100 parts by mass. The above 100 parts by mass does not include the amount of the elements of the subcomponents (e.g., the first subcomponent) dissolved in the BT-based particles 17. However, as can be seen from the ranges below, the amount of the elements of the first subcomponent dissolved in the BT-based particles 17 is relatively small, so the amount of the elements of the first subcomponent dissolved in the BT-based particles 17 may be included in the 100 parts by mass. In the following, the amount of oxide corresponding to the amount of each element is shown, assuming that each element constitutes an oxide.

(b1) Mg: 0.04 or more and 0.25 or less (MgO conversion)
(b2) RE: 0.2 or more and 2.5 or less (RE ₂ O ₃ conversion)
(b3) Mn: 0.04 or more and 0.15 or less (MnO conversion)

When the above conditions (b1), (b2) and/or (b3) are satisfied, for example, the temperature dependence of the dielectric constant can be reduced, and/or the likelihood of dielectric breakdown occurring when a voltage is applied at high temperatures can be reduced.

The amount of the first subcomponent element dissolved in the BT-based particles 17 may be the same for the BT particles and the BCT particles, or may be different. For example, the mass percentage of the first subcomponent element contained in the BCT particles may be greater than the mass percentage of the first subcomponent element contained in the BT particles. In this case, for example, the effects of increasing the relative dielectric constant, reducing the temperature dependency of the relative dielectric constant, improving insulation when a high voltage is applied at high temperatures, and improving thermal shock resistance are achieved.

The amount of impurities may be, for example, less than 2 parts by mass or less than 1 part by mass per 100 parts by mass of the BT-based particles 17. Furthermore, when aluminum is present as an impurity, the amount of aluminum may be less than 1% by mass of the dielectric.

(2.3.A/B ratio)
(2.3.1. A/B ratio in general)
As described above, the A/B ratio is a value obtained by dividing the amount of substance of the element in the A site by the amount of substance of the element in the B site in the BT-based particle 17. The element refers to the element of the main component. For example, in the first embodiment, it refers to Ba and Ti of the BT particles, and Ba, Ca, and Ti of the BCT particles. Even though an element may be substituted for either the A site or the B site element, it is not used in calculating the A/B ratio.

The main component element can be expressed as follows. The main component element in the A site is Ba or an element substituted for Ba in a significant amount in the BT-based particles 17 (Ca in the first embodiment). Examples of a significant amount include 1.0 mol% or more, or 0.5 mol% or more (the same applies below). The main component element in the B site is Ti or an element substituted for Ti in a significant amount in the BT-based particles 17.

Just to be clear, in the first embodiment, the amount of substance A (mol) of an element at the A site is the sum of the amount of substance Ba in the BT particles and the amounts of substance Ba and Ca in the BCT particles. The amount of substance B (mol) of an element at the B site is the sum of the amount of substance Ti in the BT particles and the amount of substance Ti in the BCT particles. The A/B ratio is a value in the BT-based particles 17, and the amounts of elements at the A site and B site in the grain boundary layer 19 are not taken into consideration.

The A/B ratio may be the same for the BT particles and the BCT particles, or may be different. Also, whether it is the former or the latter may be the same for the sites (7, 13, and 15) or may be different. In any case, what is compared is the A/B ratio for the entire BT-based particles 17, which includes the BT particles and the BCT particles.

If the A/B ratios of multiple effective portions 7 are different from one another, the average A/B ratio averaged by volume may be compared with the A/B ratios of other portions. If the A/B ratios differ depending on the portion within the side margin portion 13, the average A/B ratio averaged by volume may be used. The same applies to the cover portion 15. However, in any case, portions that occupy a relatively small volume and show a unique A/B ratio value may be excluded from consideration.

In determining whether or not the technology disclosed herein has been used, the A/B ratio may be determined, for example, from the weighing of the raw material of the BT-based particles 17 before the powder that will become the BT-based particles 17 is produced. However, the A/B ratio may also be determined by analysis after production. Furthermore, whether or not the technology disclosed herein has been used can be determined if the A/B ratio can be compared between the effective portion 7 and the side margin portion 13. Therefore, the value of the A/B ratio itself does not need to be strictly identifiable.

In the following description, the following symbols may be used for convenience.
A/B ratio of the effective portion 7: A/B_E
A/B ratio of the side margin portion 13: A/B_S
A/B ratio of the cover portion 15: A/B_C
・A/B_E-A/B_S (difference in A/B ratio): ΔR_S
・A/B_E-A/B_C (difference in A/B ratio): ΔR_C

As mentioned above, A/B_S is smaller than A/B_E. A/B_C may be smaller than, equal to, or larger than A/B_E. In the explanation of the embodiment, the case where A/B_C<A/B_E may be taken as an example unless otherwise specified. In this case, for example, the thermal shock resistance of the cover portion 15 is improved, similar to the side margin portion 13. A/B_S may be larger than, equal to, or smaller than A/B_C.

(2.3.2. A/B ratio of side margin)
The magnitude of ΔR_S is arbitrary. For example, if A/B_S is smaller than A/B_E to some extent, the effect described in the outline of the embodiment is achieved to some extent. Therefore, ΔR_S may be equal to or greater than a significant magnitude. For example, 0.001≦ΔR_S. In the examples described below, it has been confirmed that when ΔR_S=0.001, a significant effect is achieved compared to when ΔR_S=0.000.

However, if A/B_S is too large relative to A/B_E, the thermal shock resistance of the side margin portion 13 will actually decrease. The reason for this is that when the firing conditions are adjusted to match the effective portion 7, the sintering of the side margin portion 13 will proceed too far. Therefore, for example, ΔR_S may be set to 0.010 or less. In the examples described below, it has been confirmed that within the above range, the likelihood of the above-mentioned inconvenience occurring is low.

Just to be clear, when specifying ΔR_S, it is sufficient to specify the value to a degree necessary and sufficient to determine whether it is within a specified range. For example, it is sufficient to obtain a significant value in the least significant digit (three decimal places in the above case). Conversely speaking, it is not necessary to specify a value with a digit smaller than the least significant digit, such as 0.0104. Furthermore, if a value with a digit smaller than the least significant digit is specified, that value may be rounded off. For example, if ΔR_S is 0.010 or less, the range includes 0.0104 and does not include 0.0105. The same applies to other parameters other than ΔR_S.

As will be understood from the above description, as long as A/B_S<A/B_E, the magnitudes of these values are arbitrary. For example, the values of A/B_S and A/B_E may be in any of the following forms.
(i) 1.000<A/B_S and 1.000<A/B_E
(ii) 1.000=A/B_S and 1.000<A/B_E
(iii) A/B_S<1.000 and 1.000<A/B_E
(iv) A/B_S<1.000 and 1.000=A/B_E
(v) A/B_S<1.000 and A/B_E<1.000

For example, among (i) to (v), the closer to (i), the more likely it is that the effects of increasing the relative dielectric constant, reducing the temperature dependency of the relative dielectric constant, improving insulation when a high voltage is applied at high temperatures, and improving thermal shock resistance will be achieved. Therefore, for example, any of (i) to (iii) may be selected.

When any of the above (i) to (v) is selected, the specific ranges of values of A/B_S and A/B_E are also arbitrary. An example of the range of values when (i) to (iii) is selected is shown below.
0.997≦A/B_S<1.003
1.003≦A/B_E≦1.007

Just to be clear, A/B_S can be smaller than 0.997. A/B_E can be larger than 1.007. The boundary between A/B_S and A/B_E can be smaller or larger than 1.003.

(2.3.3. A/B ratio of cover part)
The explanation of A/B_S and ΔR_S in Section 2.3.2 above may be incorporated into A/B_C and ΔR_C by substituting the terms A/B_S and ΔR_S with the terms A/B_C and ΔR_C.

Also, as mentioned above, the magnitude relationship between A/B_S and A/B_C is arbitrary. For example, the two may be the same. In this case, for example, the raw materials for both are the same, improving productivity. When A/B_S and A/B_C are different from each other, the difference between the two may be, for example, 0.010 or less, similar to ΔR_S and ΔR_C. In this range, for example, sintering tends to proceed in the same way in the side margin portion 13 and the cover portion 15.

(3. Capacitor Manufacturing Method)
(3.1. Manufacturing Procedure)
The method for manufacturing the capacitor 1 may be various methods, and may be the same as a known method, for example, except that the A/B ratio is set depending on the portion. An example is shown below.

FIG. 4 is a flowchart showing an example of the steps in the manufacturing method for the capacitor 1.

In step ST1, a first laminate is produced. The first laminate is made up of a plurality of parts that will become laminates 11 arranged along a plane and connected to each other. The first laminate is made up of alternating layers of ceramic green sheets, including parts that will become a plurality of effective portions 7, and conductive paste that will become a plurality of internal electrodes 9.

In step ST2, a ceramic green sheet including portions that will become multiple cover portions 15 (in other words, a ceramic green sheet that overlaps almost the entire first laminate) is placed on the top and bottom surfaces of the first laminate to produce a second laminate.

In step ST3, the second laminate is singulated (divided) into portions that will become a plurality of capacitors 1 (more precisely, laminate 11 and cover portion 15). Singulation is achieved, for example, by cutting (dicing) using a blade or laser. At this time, the division surface (cut surface) along the zx plane is the surface that will become the side surface of laminate 11 that will be covered by side margin portion 13. The conductive paste that will become a plurality of internal electrodes 9 is exposed from this cut surface. Moreover, the division surface (cut surface) along the yz plane is the surface that will become the side surface (end surface) of laminate 11 that will be covered by external electrode 5. The conductive paste that will become a plurality of internal electrodes 9 is exposed from this cut surface every other layer.

It should be noted that either side may simply be cut. However, polishing, grinding, or other processing may also be performed. In this case, the conductive paste may be exposed by cutting alone, or may be exposed by the above processing without being exposed by cutting. Furthermore, the cut surface along the yz plane may be polished or ground after firing, which will be described later, thereby exposing the internal electrode 9 to the outside.

In step ST4, the ceramic green sheet that will become the side margin portion 13 is attached to the side along the zx plane of the piece (the molded body that will become the laminate 11 and cover portion 15) obtained in step ST3. Note that instead of attaching the ceramic green sheet, the ceramic material may be disposed on the side of the molded body by spraying and/or dipping. It may be considered that the ceramic green sheet that will become the side margin portion 13 is formed by this spraying and/or dipping.

In step ST5, the molded body that will become the main body 3 (laminated body 11, cover 15, and side margin 13) is fired. This produces the main body 3.

In step ST6, the external electrode 5 is formed. That is, a metal layer is formed on the side surfaces along the yz plane of the main body 3.

An example of a procedure that differs from the above is one in which step ST4 is omitted and the side margin portion 13 is formed by the outer edge portion of the ceramic green sheet that will become the effective portion 7. In this embodiment, the molded body that is singulated in step ST3 has a portion that will become the laminate 11, the cover portion 15, and the side margin portion 13. From another perspective, the conductive paste that will become the internal electrode 9 is not exposed from the side surface (cut surface) along the zx plane.

In the other procedures described above in which step ST4 is omitted, even if positional errors and/or singulation errors occur in the various parts of the second laminate, the width (length in the y direction) of the side margin portion 13 includes a margin that takes into account the above-mentioned errors so that the conductive paste that will become the internal electrodes 9 is not exposed from the side surface (cut surface) along the zx plane. On the other hand, in the procedure that includes step ST4, there is no need to take such a margin into account. As a result, it is easy to make the side margin portion 13 thinner.

In the procedure illustrated in FIG. 4, the effective portion 7 and the side margin portion 13 are fabricated separately from each other. Therefore, to make the A/B ratio different between the effective portion 7 and the side margin portion 13, the A/B ratio of the ceramic material prepared for the effective portion 7 and the side margin portion 13 may be made different from each other.

It is possible to achieve the A/B ratio according to the embodiment even in a procedure in which step ST4 is omitted. For example, A-site elements may be injected into the outer edge region of the ceramic green sheet (the portion that will become the side margin portion 13), and conversely, B-site elements may be injected into the central region (the portion that will become the effective portion 7).

(3.2. Manufacturing method of dielectric)
A method for manufacturing the dielectrics constituting the active portion 7, the side margin portion 13 and the cover portion 15 will be described below.

As can be understood from the explanation of FIG. 4, the method for manufacturing a dielectric includes a step of producing a ceramic green sheet and a step of firing a molded body produced using the ceramic green sheet. The ceramic green sheet includes a step of producing a ceramic slurry and a step of forming the ceramic slurry into a sheet shape by an appropriate sheet forming method (e.g., a doctor blade method or a die coater method). The ceramic slurry is produced, for example, by mixing a BT-based powder, which is the material of the BT-based particles 17, an additive (e.g., a sintering aid) containing an element of a minor component (e.g., a first minor component), and a binder and/or a solvent.

In the first embodiment, the BT-based powder is the material of the BT-based particles 17, so the description of the composition of the BT-based particles 17 may be appropriately applied to the BT-based powder. Just to be sure, for example, the BT-based powder has a barium titanate-based crystal having a perovskite structure represented by the composition formula ABO _3. In the first embodiment, the BT-based powder includes a BT powder that is the material of the BT particles and a BCT powder that is the material of the BCT particles. The BT particles have a crystal represented by BaTiO _3. The BCT powder has a crystal represented by (Ba _1-x Ca _x ) TiO _3. However, unlike the BT-based particles 17, the BT-based powder does not have a solid solution of the element of the first subcomponent.

The BT-based powder is produced by mixing and synthesizing compounds containing A-site and B-site elements. At this time, the amount of the compound is set so that a desired composition is obtained. For example, in the production of BCT particles, the ratio of the amount of the compound containing Ba to the amount of the compound containing Ca is set so that x in Ba _1-x Ca _x has a desired value. The BT-based powder may be obtained by a synthesis method selected from a solid-phase method, a liquid-phase method (including a method of producing via oxalate), a hydrothermal synthesis method, and the like. In addition, when the hydrothermal synthesis method is used, it is easy to narrow the particle size distribution of the powder and increase the crystallinity.

The diameter of the BT-based powder is arbitrary as long as it is equal to or smaller than the diameter of the BT-based particles 17. For example, it may be 0.01 μm or more and 0.2 μm or less. In addition, the crystallinity of the BT-based powder may be, for example, when evaluated using X-ray diffraction, such that the ratio of the peak of index (001) P _AA indicating a tetragonal crystal to the peak of index (100) P _BB indicating a cubic crystal, P _AA /P _BB , is 1.1 or more.

The amount of the additive containing an element of the first minor component may be set, for example, so as to realize the parts by mass of each element relative to the parts by mass of the BT-based particles 17 described in Section 2.2. The additive containing an element of the first minor component may be, for example, an oxide or a carbonate.

As an additive other than the additive containing the element of the first subcomponent, for example, glass powder may be used. The glass powder may be composed of, for example, Li ₂ O, SiO ₂ , BaO, and CaO. The amount of glass powder added may be, for example, 0.7 parts by mass or more and 2.0 parts by mass or less when the mass of the BT-based powder is 100 parts by mass. The composition may be, in mol%, Li ₂ O is 5 to 15, SiO ₂ is 40 to 60, BaO is 10 to 30, and CaO is 10 to 30. The content of alumina contained in the glass powder may be 0.1 mass% or less. By adding such glass powder, for example, sinterability is improved.

Examples of the binder and/or solvent include organic resins (e.g., polyvinyl butyral resins), toluene, and alcohol. The binder and/or solvent essentially disappears upon firing.

(3.3. How to set the A/B ratio)
As can be understood from the above explanation, the A/B ratio is realized by adjusting the mixing ratio between the amount of the compound containing the A site element and the amount of the compound containing the B site element according to the desired A/B ratio when preparing the BT-based particles. By varying the mixing ratio depending on the site (7, 13, and 15), different A/B ratios are realized for the sites.

4. EXAMPLES
5 and 6 are diagrams showing the specifications of the capacitors according to the examples and the comparative examples. FIG. 5 mainly shows examples and comparative examples in which the values of A/B_E and A/B_S are different from each other. It is shown that A/B_S<A/B_E improves the thermal shock resistance and the like in the side margin portion 13. FIG. 6 mainly shows examples in which the values of A/B_E and A/B_C are different from each other. It is shown that A/B_C<A/B_E improves the thermal shock resistance and the like in the cover portion 15. Specifically, it is as follows.

In Figure 5, the "No." column shows numbers that identify the examples and comparative examples. Numbers with an E (E1 to E11) indicate examples. Numbers with a C (C1 and C2) indicate comparative examples.

The "A/B_E", "A/B_S", "ΔR_S" and "A/B_C" columns indicate the values of each parameter. The "W (μm)" column indicates the value (μm) of the width of the side margin portion 13 (the length in the y direction as shown in FIG. 3). The "t (μm)" column indicates the value (μm) of the thickness of the cover portion 15 (the length in the z direction as shown in FIG. 3).

The "X5R" column indicates whether or not the product meets the EIA (Electronic Industries Alliance) X5R standard. X5R requires that the temperature change rate of capacitance from -55°C to 85°C be within ±15%, with 25°C as the reference temperature.

The "TEST1" column shows the results of the high-temperature load test. More specifically, in this test, a voltage of 9.45V was applied to the capacitors for 1000 hours in an environment of 125°C, and the capacitors that developed short circuits were judged as NG. Note that 9.45V is more than 1 time the rated voltage of the target capacitor. In Figure 5, the number of samples judged as NG out of 100 samples is shown in fractional form.

The "TEST2" column shows the results of the thermal shock test. More specifically, in this test, the temperature of the capacitor was raised to 350°C, and capacitors that had cracks in the side margin portion 13 were judged as NG. In Figure 5, the number of samples judged as NG out of 500 samples is shown in fractional form.

In Fig. 5, the shapes, dimensions and materials of the capacitors according to the embodiment and the comparative example are the same as each other except for the differences in the values of the parameters shown in the figure. The ranges of the values of the parameters shown in Fig. 5 are as follows:
A/B_E: 1.002-1.008
A/B_S: 0.996-1.008
ΔR_S: -0.001 to 0.011
A/B_C: 1.000
(ΔR_C: 0.002 to 0.008)
W: 20 μm
t: 20 μm

E1 to E11 are examples because they satisfy A/B_S<A/B_E. C1 and C2 are comparative examples because they do not satisfy A/B_S<A/B_E. More specifically, in C1, A/B_S=A/B_E, and in C2, A/B_E<A/B_S. And in TEST2, the number of NGs was 5/500 in C1 and C2, whereas the number of NGs was 0/500 or 1/500 in E1 to E11. This confirmed that thermal shock resistance was improved when A/B_S<A/B_E.

E10 has a ΔR_S of 0.011, which does not satisfy the condition ΔR_S≦0.010. On the other hand, the other examples satisfy the above condition. And for TEST2, the number of NGs is 1/500 for E10, whereas the number of NGs is 0/500 for the other examples. This confirms that thermal shock resistance is improved by ΔR_S≦0.010.

Furthermore, all of the examples were favorably evaluated in terms of X5R and TEST1 compared to the comparative examples. Specifically, all of the examples satisfied X5R, whereas all of the comparative examples did not satisfy X5R. Furthermore, with regard to TEST1, the number of NGs was 0/100 in all of the examples, whereas the number of NGs was 3/100 or 2/100 in the comparative examples. From these results, it was confirmed that A/B_S<A/B_E can also contribute to reducing the temperature dependency of capacitance and improving resistance to high-temperature loads. The reason for this is that the side margin portion 13 is sintered in the same way as the effective portion 7, thereby reducing the likelihood of unintended effects (e.g., stress) being applied from the side margin portion 13 to the effective portion 7.

FIG. 6 is a chart similar to FIG. 5. However, in FIG. 6, the value of "ΔR_S" is not shown, and instead the value of "ΔR_C" is shown. Also, "TEST3" is shown instead of "TEST2". In "TEST3", like "TEST2", the temperature of the capacitor is raised to 350°C, and capacitors in which cracks have occurred are judged as NG. However, while "TEST2" judged whether there were cracks in the side margin portion 13, "TEST3" judged whether there were cracks in the cover portion 15.

In Fig. 6 (and Fig. 5), the shapes, dimensions and materials of the capacitors according to the examples are the same as each other, except for the different values of the parameters shown in the figures. The ranges of the values of the parameters shown in Fig. 6 are as follows:
A/B_E: 1.002-1.008
A/B_S: 1.000
(ΔR_S: 0.002 to 0.008)
A/B_C: 0.996-1.008
ΔR_C: -0.001 to 0.011
W: 20 μm
t: 20 μm or 25 μm

All of the examples in Figure 6 (E12 to E24) are working examples because they satisfy A/B_S < A/B_E. Note that although there are working examples with a relatively large number of NGs in "TEST3," as mentioned above, please note that "TEST3" is not an evaluation of the thermal shock resistance of the side margin portion 13.

FIG. 6 shows that the same results as for the side margin portion 13 are obtained for the cover portion 15 with respect to the setting of the A/B ratio. That is, the examples (E12-E21 and E23) that satisfy the condition A/B_C<A/B_E have improved thermal shock resistance (evaluation in TEST3) of the cover portion 15 compared to the examples (E22 and E24) that do not satisfy the above condition. Also, among the former examples, the examples (E12-E20 and E23) that satisfy the condition ΔR_C≦0.010 have improved thermal shock resistance compared to the example (E21) that does not satisfy the above condition. Furthermore, because A/B_C<A/B_E, favorable evaluations are obtained for X5R and TEST1 as well.

(5. Summary of the First Embodiment)
As described above, the multilayer electronic component (capacitor 1) according to the embodiment has a laminate 11 and a side margin portion 13. The laminate 11 has (a plurality of) effective portions 7 and (a plurality of) internal electrodes 9 that are alternately stacked. The side margin portion 13 overlaps the side surface of the laminate 11 along the stacking direction (z direction). Both the effective portion 7 and the side margin portion 13 are made of polycrystalline ceramics. The polycrystalline ceramics include barium titanate-based BT-based particles 17 having a perovskite structure represented by the composition formula _ABO3 . The A site of the BT-based particles 17 includes Ba. The B site of the BT-based particles 17 includes Ti. When the amount of substance of the element at the A site in the BT-based particles 17 divided by the amount of substance of the element at the B site is referred to as the A/B ratio, the A/B ratio (A/B_S) of the side margin portion 13 is smaller than the A/B ratio (A/B_E) of the effective portion 7.

From another point of view, the manufacturing method of the laminated electronic component (capacitor 1) according to the embodiment includes a compact step (steps ST1 to ST4) and a firing step (step ST5). In the compact step, a compact (see main body 3) is obtained. In the compact (3), a second ceramic green sheet (see side margin 13) is overlapped on a side surface along the lamination direction (z direction) of the laminate (see laminate 11). The laminate (11) has (a plurality of) first ceramic green sheets (see effective portion 7) and (a plurality of) conductive pastes (see internal electrodes 9) that are alternately laminated. In the firing step, the compact (3) is fired. Both the first ceramic green sheet (7) and the second ceramic green sheet (13) contain BT-based powder (see BT-based particles 17) of barium titanate having a perovskite structure represented by the composition formula _ABO3 . The A site of the BT-based powder contains Ba. The B site of the BT-based powder contains Ti. When the amount of substance of an element at the A site in a BT-based powder divided by the amount of substance of an element at the B site is called the A/B ratio (A/B_S), the A/B ratio of the second ceramic green sheet (13) is smaller than the A/B ratio (A/B_E) of the first ceramic green sheet (7).

In this case, for example, as described in the description of the outline of the embodiment, it becomes easier to sinter the effective portion 7 and the side margin portion 13 in a similar manner, and the thermal shock resistance can be improved. This makes it possible to reduce the width W of the side margin portion 13 without reducing the strength of the side margin portion 13, thereby making the capacitor 1 smaller in size in a plan view. Furthermore, as shown with reference to FIG. 5 of the embodiment, this is also advantageous in reducing the temperature dependency of the capacitance and improving resistance to voltage application in a high-heat environment.

The difference (ΔR_S) between the A/B ratio of the side margin portion 13 and the A/B ratio of the effective portion 7 may be 0.010 or less.

In this case, for example, as shown with reference to FIG. 5, the likelihood of the inconvenience of the thermal shock resistance of the side margin portion 13 being reduced by making A/B_S smaller than A/B_E can be reduced.

The capacitor 1 may have a cover portion 15. The cover portion 15 may overlap the surface (upper or lower surface) of the laminate 11 facing the stacking direction, and may be made of the polycrystalline ceramics described above with respect to the active portion 7 and the side margin portion 13. The A/B ratio of the cover portion 15 may be smaller than the A/B ratio of the active portion 7.

In this case, for example, it is easier to sinter the effective portion 7 and the cover portion 15 in the same manner as the side margin portion 13, and the thermal shock resistance can be improved. This makes it possible to reduce the thickness t of the cover portion 15 without reducing the strength of the cover portion 15, thereby making the capacitor 1 smaller in side view. Furthermore, as shown with reference to FIG. 6 of the embodiment, this is also advantageous in reducing the temperature dependency of the capacitance and improving resistance to voltage application in a high-heat environment. In addition, since it is easier to sinter the side margin portion 13 and the cover portion 15 in the same manner, the likelihood of cracks occurring due to thermal stress between the two is also reduced. This dramatically improves the thermal shock resistance of the capacitor 1 as a whole.

The difference (ΔR_C) between the A/B ratio of the cover portion 15 and the A/B ratio of the effective portion 7 may be 0.010 or less.

In this case, for example, as shown with reference to FIG. 6, the likelihood of the disadvantage of the thermal shock resistance of the cover portion 15 being reduced by making A/B_C smaller than A/B_E can be reduced.

The BT-based particles 17 may include BT particles and BCT particles. The BT particles have Ba at the A site and Ti at the B site. The BCT particles have _Ba1-xCax _at the A site and Ti at the B site. The A/B ratio of the effective portion 7 may be 1.003 or more and 1.007 or less. The A/B ratio of the side margin portion 13 may be 0.997 or more and less than 1.003.

The above A/B ratio is roughly the range of the A/B ratio shown in Figure 5. If it is within this range, there is a high probability that the effects of improving thermal shock resistance, reducing temperature dependency, and improving high-temperature load reliability will be achieved, for example.

Chapter B. Other Embodiments
In the first embodiment, BT particles and BCT particles are shown as the BT-based particles 17. Other BT-based particles 17 include, for example, the following.
BST particles with Ba _1-x Sr _x at the A site and Ti at the B site BCST particles with Ba _1-x-y Ca _x Sr _y at the A site and Ti at the B site

In the first embodiment, the BT-based particles 17 are a combination of BT particles and BCT particles. The BT-based particles 17 may be composed of one or more types of particles selected from four types of particles, for example, BT _particles , BCT particles, BST particles, and BCST particles. In this case, including the first embodiment (BT+BCT), there are 15 (= _4C1 + _4C2 + _4C3 + _4C4 ₌ ₄ + ₆ +4+1) types. Any of these may be adopted. For example, the following may be adopted as an embodiment other than the first embodiment.
・BST+BCST
・BT+BST
・BT+BCST

When one or more types of particles are selected from the above four types of BT-based particles 17, the component ratios and the like shown in Section 2.2 may be used as appropriate. For example, they are as follows.

It is clear that (a1) may be applied to any embodiment. In (a2), the total amount of BT particles and BCT particles may be read as the total amount of one or more selected types of particles.

It is clear that (a3) is applicable in an embodiment in which two types of particles are selected as the BT-based particles 17. It is also clear that (a3) does not need to be taken into consideration in an embodiment in which one type of particle is selected. In an embodiment in which three or more types of particles are selected, for example, (a3) may be established regardless of which two types of particles are selected from the above three or more types of particles. Of course, (a3) does not necessarily have to be established when two, three, or four types are selected.

(a4) may be incorporated in BST. In this case, x in (a4-1) may be x in Ba _1-x Sr _x . In BCST, (a4-1) may be incorporated (or may not be incorporated) for the range of x in Ba _1-x-y Ca _x Sr _y . In addition, (a4-2) can be incorporated (or may not be incorporated) when the A site contains three or more elements, as in BCST. The value of y in BCST may be, for example, 0.01 to 0.20, or 0.02 to 0.07, similar to x in (a4-1). In this case, x+y may be 0.30 or less or 0.20 or less so that (a4-2) is satisfied, or may not be so.

It is clear that (a5) to (a7) and (b1) to (b3) as well as the conditions relating to impurities may be applied to various aspects.

The method of calculating the A/B ratio is the same as in the first embodiment in other embodiments. To be sure, in the BST+BCST embodiment, the amount of substance in the A site is the sum of the amounts of substance of Ba, Sr, and Ca in the BST particles and the BCST particles. The amount of substance in the B site is the same as in the first embodiment. In the BT+BST embodiment, the amount of substance in the A site is the sum of the amounts of substance of Ba and Sr in the BT particles and the BST particles. The amount of substance in the B site is the same as in the first embodiment. In the BT+BCST embodiment, the amount of substance in the A site is the sum of the amounts of substance of Ba, Ca, and Sr in the BT particles and the BCST particles. The amount of substance in the B site is the same as in the first embodiment.

The technology disclosed herein is not limited to the above embodiments and may be implemented in various forms.

For example, the multilayer electronic component is not limited to a capacitor. For example, in a multilayer electronic component, some of the internal electrodes may form a capacitor, and other parts of the internal electrodes may form an inductor or resistor. The multilayer electronic component may form an appropriate circuit (for example, a resonant circuit) as a whole. Furthermore, it is sufficient that at least a part of the multilayer electronic component is formed of a laminate in which active parts (two or more) and internal electrodes (two or more) are stacked, and the majority of the multilayer electronic component does not necessarily have to be formed of a laminate.

From this disclosure, a concept may be extracted that does not require that the A/B ratio of the side margin portion be smaller than the A/B ratio of the effective portion. For example, a technical idea may be extracted that is characterized in that the A/B ratio of the cover portion is smaller than the A/B ratio of the effective portion, or a technical idea that the difference between the A/B ratio of the side margin portion and the A/B ratio of the cover portion falls within a predetermined range. In this case, unlike the embodiment, the A/B ratio of the side margin portion may be equal to or greater than the A/B ratio of the effective portion. Also, a side margin portion need not be provided.

1...capacitor (multilayer electronic component), 7...active part, 9...internal electrode, 11...laminated body, 13...side margin part, 15...cover part, 17...BT-based particles.

Claims

a laminate having alternating active portions and internal electrodes;
A side margin portion overlapping a side surface of the laminate along the stacking direction;
It has
the effective portion and the side margin portion are both made of polycrystalline ceramics,
The polycrystalline ceramic contains barium titanate-based BT-based particles having a perovskite structure represented by the composition formula ABO3 ,
The A site of the BT-based particles contains Ba,
The B site of the BT-based particles contains Ti,
When the amount of substance of an element at the A site in the BT-based particles divided by the amount of substance of an element at the B site is called the A/B ratio, the A/B ratio of the side margin portion is smaller than the A/B ratio of the effective portion.
2. The multilayer electronic component according to claim 1, wherein a difference between an A/B ratio of said side margin portion and an A/B ratio of said effective portion is 0.010 or less.
a cover portion overlapping a surface of the laminate facing the stacking direction and made of the polycrystalline ceramic;
The multilayer electronic component according to claim 1 or 2, wherein an A/B ratio of the cover portion is smaller than an A/B ratio of the effective portion.
4. The multilayer electronic component according to claim 3, wherein a difference between an A/B ratio of said cover portion and an A/B ratio of said effective portion is 0.010 or less.
The BT-based particles are
BT particles in which the A site is Ba and the B site is Ti;
BCT particles in which the A site is Ba 1-x Ca x and the B site is Ti;
The multilayer electronic component according to any one of claims 1 to 4, comprising one or more types of particles selected from the following four types of particles: BST particles having Ba1- xSrx at the A site and Ti at the B site; and BCST particles having Ba1-x-yCaxSry at the A site and Ti at the B site.
the BT-based particles include the BT particles and the BCT particles,
the A/B ratio of the effective portion is 1.003 or more and 1.007 or less,
The multilayer electronic component according to claim 5 , wherein the A/B ratio of the side margin portion is equal to or greater than 0.997 and less than 1.003.
a compacting step of obtaining a compact in which a second ceramic green sheet is overlapped on a side surface along a stacking direction of a laminate having first ceramic green sheets and conductive paste alternately stacked;
A firing step of firing the molded body;
It has
The first ceramic green sheet and the second ceramic green sheet each contain a barium titanate-based BT-based powder having a perovskite structure represented by a composition formula ABO3 ,
The A site of the BT powder contains Ba,
The B site of the BT-based powder contains Ti,
When the amount of substance of an element at the A site in the BT-based powder divided by the amount of substance of an element at the B site is called an A/B ratio, the A/B ratio of the second ceramic green sheet is smaller than the A/B ratio of the first ceramic green sheet.