Multilayer electronic component and method for manufacturing same

Abstract

This multilayer electronic component has a laminate and a side margin portion. The laminate has an effective portion and an internal electrode which are alternately overlapped. The side margin portion overlaps a side surface, of the laminate, that extends along the lamination direction. Both the effective portion and the side margin portion are made of a polycrystalline ceramic. The polycrystalline ceramic contains one or more elements contained in one or more additives that promote sintering. The mol% of the one or more elements in the side margin portion is larger than the mol% of the one or more elements in the effective portion.

Description

Multilayer electronic component and its manufacturing method

[0001] The present disclosure relates to a multilayer electronic component and a manufacturing method thereof. BACKGROUND 1. Technical Field The present disclosure relates to a multilayer electronic component such as a multilayer ceramic capacitor.

[0002] A multilayer ceramic capacitor having a plurality of dielectric layers and a plurality of internal electrodes alternately stacked is known (see, for example, Patent Document 1 below). In Patent Document 1, the dielectric layers are mainly made of BaTiO ３ and BaTiO ３ A part of Ba was replaced with Ca (Ba １－ｘ Ca ｘ ) TiO ３ and crystal grains of the dielectric layer. The dielectric layer also contains elements contained in the additive (e.g., Mg, rare earth elements, and Mn). The contents of Patent Document 1 may be incorporated by reference in this disclosure.

[0003] Japanese Patent Application Laid-Open No. 2006-156450

[0004] A multilayer electronic component according to one aspect of the present disclosure includes a laminate and a side margin portion. The laminate has alternately overlapping effective portions and internal electrodes. 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 ceramic. The polycrystalline ceramic contains one or more elements contained in one or more additives that promote sintering. The mole percentage of the one or more elements in the side margin portion is greater than the mole percentage of the one or more elements in the effective portion.

[0005] A method for manufacturing a multilayer electronic component according to one aspect of the present disclosure includes a compacting step for obtaining a compact and a firing step for firing the compact. In the compact, a laminate having first ceramic green sheets and a conductive paste alternately stacked is formed, and a second ceramic green sheet is overlapped on a side along the stacking direction of the laminate. The first ceramic green sheet and the second ceramic green sheet both contain one or more additives that promote sintering. The mole percentage of the one or more additives in the second ceramic green sheet is greater than the mole percentage of the one or more additives in the first ceramic green sheet.

[0006] 1 is a perspective view showing a multilayer ceramic capacitor according to an embodiment; 2 is a cross-sectional view taken along line II-II in FIG. 1; 3 is a cross-sectional view taken along line III-III in FIG. 1; 4 is a flowchart showing the steps of a method for manufacturing the capacitor of FIG. 1; 5 is a table showing the specifications of capacitors according to examples and comparative examples; and 6 is a table showing the characteristics of capacitors according to examples and comparative examples.

[0007] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The drawings used in the following description are schematic. Therefore, for example, the dimensional ratios in the drawings do not necessarily correspond to the actual ones. 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.

[0008] (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, Fig. 1 and other figures described below are illustrated with a Cartesian coordinate system xyz. The capacitor 1 may be used with either side designated as the upper or lower side. However, in the description of the embodiment, for convenience, the +z side may be designated as the upper side, and terms such as upper surface and lower surface may be used.

[0009] The capacitor 1 has, for example, a substantially rectangular parallelepiped main body 3 and a pair of external electrodes 5 located on both ends of the main body 3. The external electrodes 5 contribute to electrical connection between the capacitor 1 and other electronic components (for example, a circuit board (not shown)).

[0010] 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 are alternately stacked. 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, with the effective portion 7 interposed therebetween. 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 formed by the multiple effective portions 7 and multiple internal electrodes 9 is referred to as a laminate 11.

[0011] 3 is a cross-sectional view taken along line III-III in FIG. 1. Also shown in FIG. 3 is an enlarged view of a portion of the dielectric constituting 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 to, for example, insulating the internal electrode 9 from the outside and / or improving the strength of the main body 3.

[0012] As shown in the partially enlarged view of Fig. 3, the polycrystalline ceramic has, for example, crystal grains 17 and grain boundary layers 19 between the crystal grains 17. Although not specifically shown, the polycrystalline ceramic also has one or more elements contained in one or more additives that promote sintering. Such elements may be present, for example, as a solid solution within the crystal grains 17 or as an amorphous substance in the grain boundary layers 19.

[0013] The additives that promote sintering referred to here include not only those added for the purpose of promoting sintering (sintering aids), but also those added for other purposes but which have a significant effect of promoting sintering. Sintering causes densification and grain growth, and the promotion of sintering referred to here simply means promoting densification. In the following description, unless otherwise specified or where there is a contradiction, the term "additive" refers to an additive that promotes sintering.

[0014] The additives may contain various elements. The type of element may be appropriately selected depending on the material of the crystal grains 17 and the properties required for the capacitor 1. For example, when the crystal grains 17 are made of barium titanate (BaTiO ３ In the case of a BT-based alloy (hereinafter sometimes referred to as a "BT-based alloy"), examples of the elements include Mg, rare earth (RE) elements, Si, Mn, and V.

[0015] The above-mentioned elements may be contained in a compound (e.g., an oxide) added to the raw material powder that becomes the crystal grains 17 during the manufacturing process of the polycrystalline ceramic. In this case, the compound may contribute to promoting sintering, and / or the element contained in the compound may contribute to promoting sintering. In the following description, for convenience, the term "additive" (which may be a compound) may not be distinguished from the term "element contained in the additive." The two terms may be interchangeable as long as no contradiction occurs.

[0016] Here, the mole percentage of one or more elements contained in one or more additives in the side margin portion 13 is greater than the mole percentage of the one or more elements in the effective portion 7. This, for example, improves 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.

[0017] In manufacturing the main body 3, for example, ceramic green sheets that will become the effective portion 7 and conductive paste that will become the internal electrodes 9 are laminated to produce a pre-fired laminate 11. Next, ceramic green sheets that will become the side margin portions 13 are attached to the side surfaces of the pre-fired laminate 11 to form a molded body. Thereafter, the molded body is fired.

[0018] A comparative example of the technology involves an embodiment in which the mol % of additives is the same in the effective portion 7 and the side margin portion 13. In this comparative example, the effective portion 7 sinters more easily than the side margin portion 13 during firing. Therefore, for example, if firing conditions are tailored to 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. One reason why the effective portion 7 sinters more easily than the side margin portion 13 is that the conductive paste that becomes the internal electrode 9 shrinks, applying stress to the effective portion 7.

[0019] Therefore, when the mole percentage of additives in the side margin portion 13 is made larger than that in the effective portion 7, the degree of sintering becomes closer between the side margin portion 13 and the effective portion 7. As a result, even under firing conditions tailored to the effective portion 7, for example, the side margin portion 13 is sufficiently sintered, and the strength of the side margin portion 13 is improved.

[0020] From another perspective, the above means that the firing conditions for the effective portion 7 can be adapted to suit the effective portion 7. As a result, for example, it is possible to improve the characteristics relating to the temperature dependency of capacitance and improve the insulating properties of the effective portion 7 while maintaining the thermal shock resistance of the side margin portion 13.

[0021] 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 ensuring 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.

[0022] The above is an overview of the capacitor 1 according to the embodiment. The following describes the embodiment roughly in the following order: 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. Crystal grains 2.2. Additives 2.3. Examples of component ratios, etc. 2.4. Differences in mole percentage of additives between multiple portions 3. Capacitor manufacturing method (FIG. 4) 3.1. Manufacturing procedure 3.2. Dielectric manufacturing method 4. Examples (FIGS. 5 and 6) 5. Summary of the embodiment

[0023] (1. Capacitor Structure) (1.1. Structure of the Illustrated Examples) As can be understood from the overview of the above-described embodiments, 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, for convenience, in describing the embodiments, the explanation may be based on the configuration illustrated in FIGS. 1 to 3 unless otherwise specified. The structure of the capacitor 1 illustrated in FIGS. 1 to 3 is as follows.

[0024] In addition to the components already described (the laminate 11, the side margins 13, and the external electrodes 5), the capacitor 1 also has a pair of cover portions 15 (reference numerals shown in FIGS. 2 and 3 ) that overlap the upper and lower surfaces of the laminate 11. The cover portions 15 are made of polycrystalline ceramics, for example, similar to the active portion 7 and the side margins 13. The cover portions 15 contribute to insulating the internal electrodes 9 from the outside and / or improving the strength of the main body portion 3.

[0025] As already mentioned, the shape of the main body 3 (or the entire capacitor 1; the same applies hereinafter in this paragraph) is a roughly rectangular parallelepiped. For example, the height (length in the z direction) of this rectangular parallelepiped may be equal to or smaller than the width (length in the y direction) (as in the illustrated example). 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.

[0026] 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 a relatively thin thickness include 3 μm or less or 1 μm or less. The planar shape of the effective portion 7 is arbitrary, and in the illustrated example, it is rectangular. The multiple effective portions 7 have, for example, the same shape, size, and material. The number of stacked effective portions 7 (internal electrodes 9) is arbitrary.

[0027] The internal electrode 9 is a layer having a constant thickness. The thickness of the internal electrode 9 is arbitrary. For example, it may be thinner (as in the illustrated example), equal to, or thicker than the thickness of the effective portion 7. The internal electrode 9 overlaps the entire effective portion 7, for example, 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 -x side or +x side region from the planar shape of the effective portion 7. The width (length in the x direction) of the -x side or +x side region 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.

[0028] The side margin portion 13 is a layer having a generally constant thickness. However, the outer corners of the main body portion 3 may be rounded. The thickness of the side margin portion 13 is arbitrary, and may be, for example, thicker than (as in the illustrated example), equal to, or thinner than the thickness of the active 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 surface of the laminate 11, but also the side surfaces of the upper and lower cover portions 15. In other words, the side margin portion 13 constitutes the entire -y or +y side surface 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.

[0029] The cover portion 15 is in the form of a layer having a generally 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 effective 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.

[0030] The uppermost or lowermost layer of the laminate 11 may be the internal electrode 9 (in the illustrated example) or the effective portion 7. In other words, the cover portion 15 may overlap the internal electrode 9 (in the illustrated example) or the effective portion 7.

[0031] 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 face on the -x side or +x side of the laminate 11. The thickness of the external electrode 5 is arbitrary. For example, the external electrode 5 may be configured by stacking layers made of different materials. The external electrode 5 is bonded to a pad on a circuit board or the like by a conductive bonding material such as solder. In this way, the capacitor 1 is mounted on the circuit board or the like.

[0032] (1.2. Structure of Examples Other Than the Examples Shown) Examples of the structure of the capacitor 1 other than the examples shown in the drawings will be given below.

[0033] The capacitor 1 may have an exterior resin covering the entire structure shown in the figure, and lead wires connected to the external electrodes 5 and extending from the exterior resin. Alternatively, grooves extending in the z direction may be formed on the side surfaces of the main body 3 in the y and / or x directions, and some or all of the external electrodes may be formed by metal filled or deposited in these grooves. As described above, any configuration may be used for mounting the capacitor 1. As can be understood from the above, the side surfaces of the laminate 11 covered by the side margin portions 13 do not have to be side surfaces along the longitudinal direction of the laminate 11, and do not have to be side surfaces on which external electrodes are provided.

[0034] The capacitor 1 does not necessarily have to have a cover portion 15. For example, the internal electrodes 9 of the uppermost or lowermost layer may be covered by the effective portion 7. In this case, however, the effective portion 7 covering the internal electrodes 9 of the uppermost or lowermost layer may be regarded as a cover portion 15 made of the same material as the effective portions 7 between the internal electrodes 9.

[0035] 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. 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.

[0036] Furthermore, the internal electrodes 9 connected to different external electrodes 5 may be arranged to face each other two by two, instead of facing each other one by one. In this case, for example, the thickness of the effective portion 7 between the internal electrodes 9 connected to the same external electrode 5 and facing each other may be thinner than the thickness of the effective portion 7 between the internal electrodes 9 connected to different external electrodes 5 and facing each other. As can be understood from this, the multiple effective portions 7 do not need to have the same shape and size.

[0037] The internal electrode 9 does not have to be exposed from the side surface (the −y side or +y side side) of the laminate 11 over the entire length (the entire length in the x direction) of the side surface covered by the side margin portion 13. For example, only a part of the internal electrode 9 may be exposed from the side surface. Furthermore, 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.

[0038] (2. Dielectrics) The dielectrics constituting the active portion 7, the side margin portion 13, and the cover portion 15 may be the same or different from one another in terms of the mol% of the additives that promote sintering. However, in the description of the embodiment, for convenience, unless otherwise specified, it is assumed that the dielectrics are the same in terms of the mol% of the additives in the respective portions. For example, the material of the crystal grains 17 is the same in the respective portions.

[0039] (2.1. Crystal Particles) As described above, the additives added to the raw material powder during the manufacturing process are dissolved in the crystal particles 17. Unless otherwise specified and unless there is any contradiction, the explanation of the material of the crystal particles 17 will be an explanation of the main component (components excluding the additives) (an explanation of the material of the raw material powder unless there is any contradiction). The main component of the crystal particles 17 accounts for, for example, 95 mol % or more of the crystal particles 17.

[0040] The material of the crystal grains 17 is arbitrary in the effective portion 7, the side margin portion 13, and the cover portion 15. For example, as described above, the material of the crystal grains 17 may be a BT-based material. From another perspective, the dielectric may be a ferroelectric.

[0041] In the description of the embodiment, for convenience, a BT-based material may be taken as an example unless otherwise specified. Furthermore, the material of the additive may also be taken as an example assuming that the material of the crystal particles 17 is a BT-based material unless otherwise specified.

[0042] The BT-based crystal particles 17 (hereinafter sometimes referred to as "BT-based particles") have a perovskite structure and have the composition formula ABO ３ 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 are represented by BaTiO ３ In the above formula, a part of Ba is not substituted with other elements or is substituted with other elements, and a part of Ti is not substituted with other elements or is substituted with other elements.

[0043] ABO ３The O in the formula is oxygen. However, some of the O may be substituted. ３ The O in ABO may be interpreted as indicating an O site, not oxygen. ３ However, in the description of the embodiments, unless otherwise specified or unless a contradiction occurs, O may be considered to represent oxygen.

[0044] Examples of elements used to partially replace Ba include elements belonging to Group 2 like Ba (e.g., Ca, Sr, and Mg), and examples of elements used to partially replace Ti include elements belonging to Group 4 like Ti (e.g., Zr and Hf).

[0045] Examples of BT-based particles are listed below. The following four types may be referred to as the "four main types." In the description of the embodiments, unless otherwise specified, the BT-based particles may be expressed on the assumption that they are one or more types of particles selected from the four main types. BaTiO ３ (Sometimes abbreviated as "BT") ・Ba １－ｘ Ca ｘ TiO ３ (Sometimes abbreviated as "BCT") ・Ba １－ｘ Sr ｘ TiO ３ (Sometimes abbreviated as "BST") ・Ba １－ｘ－ｙ Ca ｘ Sr ｙ TiO ３ (Sometimes abbreviated as "BCST.")

[0046] As described above, the description of the embodiment basically takes as an example an embodiment in which the material of the crystal particles 17 is the same among the effective portion 7, the side margin portion 13, and the cover portion 15, but different portions may be made of different materials for the crystal particles 17. For example, in an embodiment in which the crystal particles 17 are made of one or more types of BT-based particles selected from the four main types, the selected BT-based particles may be different depending on the portion, or the ratio of the amounts of substance of two or more types of BT-based particles may be different.

[0047] In an embodiment in which the BT-based particles are composed of one or more types of particles selected from the four main types, the ratio of the amount of substance of BT particles to the amount of substance of the BT-based particles is referred to as the "BT ratio." The BT ratio ranges from 0 mol% to 100 mol%. The smaller the BT ratio, the easier sintering progresses. In an embodiment, the BT ratios are the same between the regions. The embodiment in which the BT ratios are the same may include an embodiment in which the difference in the BT ratios between the two regions is less than 1 mol% or less than 0.5 mol%. Alternatively, the BT ratio of the side margin portion 13 may be smaller than the BT ratio of the effective portion 7. This can improve the effects described above, for example, by increasing the mol% of the additive in the side margin portion 13.

[0048] (2.2. Additives) The type of element contained in the additive is arbitrary. For example, in addition to the elements exemplified in the description of the outline of the embodiment (Mg, RE, Si, Mn, and V), alkaline earth metal elements (e.g., Ca and Sr) and Cr can be mentioned. RE may be, for example, one or more elements selected from La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, and Sc.

[0049] Mg and RE contribute to the formation of a core-shell structure, for example. 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 17 (BT-based particles) rather than the center. The core-shell structure reduces, for example, the temperature dependence of the dielectric constant and / or reduces the DC bias characteristics. Mn, Cr, and V compensate for, for example, oxygen defects in the crystal particles, contributing to improving insulation properties and high-temperature load life. Si and alkaline earth metals are contained in, for example, glass powder added to the raw material powder that becomes the crystal particles 17, and contribute to promoting sintering.

[0050] As described above, the various elements described above may be contained in, for example, oxides as additives. In this case, O can be said to be an element contained in the additives that promote sintering. O is an element contained in the ABO of the BT-based particles during the manufacturing process. ３It is clear whether O is included in the additive or in the additive. However, after manufacturing, it may be difficult to determine which it is. In such a case, when evaluating the mol % of the additive in the manufactured capacitor 1, O may not be treated as an element included in the additive. Furthermore, even during the manufacturing process, the mol % of O increases according to the mol % of the element bonding with O. Therefore, the effect of the present disclosure can be achieved as long as the mol % of the element bonding with O in the side margin portion 13 is greater than that in the effective portion 7. From this perspective, O may not be treated as an element included in the additive, regardless of whether it is during the manufacturing process or not. The same applies to crystal particles 17 other than BT-based particles and elements other than O, which have similar circumstances.

[0051] As described above, in the BT-based particles, a portion of the Ba may be substituted with Ca and / or Sr. During the manufacturing process, it is clear whether Ca and Sr are contained in the raw material powder that becomes the BT-based particles or in the additives. However, after manufacturing, it may be difficult to determine which is which. In such cases, when evaluating the mole percentage of the additives in the manufactured capacitor 1, Ca and Sr may not be treated as elements contained in the additives. The effects of Ca and Sr can be evaluated using the BT ratio described above. The same applies to crystal particles 17 and other elements other than BT-based particles that have similar circumstances.

[0052] Crystal particles 17 in which a large amount of the main component element is substituted with an additive element may be considered to be crystal particles of a material different from the material of the intended crystal particles (raw material powder that will become crystal particles). For example, when the amount of substitution (not simply the amount of solid solution) is 1.0 mol % or more or 0.5 mol % or more, they may be considered to be another type of crystal particle 17. Conversely, for example, BT particles may be considered to have Ba substitution amounts and Ti substitution amounts each less than 0.5 mol %.

[0053] The dielectric may contain components (hereinafter, sometimes referred to as "impurities") that are derived from additives or the like and are not intended to contribute to sintering or the like. Examples of impurities include those (e.g., aluminum) derived from glass powder mixed in the dielectric manufacturing process.

[0054] (2.3. Examples of component ratios, etc.) Various values ​​such as mass % and mol % of each component may be set as appropriate, and known values ​​disclosed in, for example, Patent Document 1 may be referenced. Examples of value ranges are shown below. Just to be clear, the conditions relating to the ranges exemplified below do not have to be satisfied. The values ​​shown below are values ​​determined, for example, from the weighing of raw materials during the manufacturing process. However, the values ​​below may also be analytical values ​​after manufacturing.

[0055] The BT-based particles are as follows. (a1) Amount of BT-based particles (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 (minor errors excluded) of all crystal particles (not limited to BT-based particles) contained in the dielectric, and / or 95 mol % or more, 98 mol % or more, or 100 mol % or more (minor errors excluded) (a2) Total amount of particles of four main types (BT, BCT, BST, and BCST): 95% by mass or more, 98 mol % or more, or 100% by mass (minor errors excluded) of BT-based particles, and / or 95 mol % or more, 98 mol % or more, or 100 mol % or more (minor errors excluded) (a3) ​​Relationship between the amounts of BT particles and one or more types of particles selected from the other three types (BCT, BST, and BCST) when they are combined. For convenience, the case where only BCT particles are selected is taken as an example. (a3-1) Area ratio of BT particles to BCT particles in the cross section or surface of the 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 in the three types of particles (BCT, BST, and BCST) other than BT particles and the amount of element (Ca and / or Sr) substituting for Ba (a4-1) Ba １－ｘ Ca ｘ x, Ba １－ｘ Sr ｘ x or Ba １－ｘ―ｙ Ca ｘ Sr ｙ(a4-2) Ba is 70 mol % or more or 80 mol % or more of the A site. (a5) Amount of Ti in the BT-based particles: 90 mol % or more, 95 mol % or more, or 100 mol % of the B site (minor errors excluded). (a6) Amount of O (oxygen) in the BT-based particles: 90 mol % or more, 95 mol % or more, or 100 mol % of the O site (minor errors excluded). (a7) Diameter of the BT-based particles: 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. (a8) Amount of substance of the element in the A site divided by the amount of substance of the element in the B site (A / B ratio): 0.997 or more and 1.007 or less, or 1.003 or more and 1.007 or less.

[0056] When the above conditions (a1) and (a2) are satisfied, for example, the properties of the BT-based crystals and the properties of the four main types of particles are easily exhibited, and as a result, 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.

[0057] When the above condition (a3) ​​is satisfied, for example, a certain amount of BT-based particles (e.g., BCT particles) other than BT particles is ensured, and the effect of reducing the temperature dependence of the dielectric constant and the DC bias characteristics is easily obtained.

[0058] When the above condition (a4-1) is satisfied, the phase transition point near room temperature is shifted to a sufficiently low temperature side, which makes it easier to obtain the effect of reducing the temperature dependency of the relative dielectric constant and the DC bias characteristics, for example.

[0059] When the above conditions (a4-2), (a5), and (a6) are satisfied, the properties of barium titanate (BT) are easily maintained, and as a result, for example, the relative dielectric constant can be easily increased.

[0060] When the above condition (a7) is satisfied, for example, the particle size is relatively small, which makes it 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.

[0061] The A / B ratio in (a8) is the composition formula ABO ３ From this perspective, the A / B ratio is 1. However, in reality, the A / B ratio can take a value other than 1. From another perspective, for example, some BT-based particles do not have a perovskite structure that strictly conforms to theory. When the A / B ratio is 1.003 or more, for example, it is possible to reduce the variation in grain growth, increase the relative dielectric constant, and / or reduce changes in characteristics due to temperature changes. When the A / B ratio is less than 1.000, the ceramic material is more easily sintered than when the A / B ratio is 1.000 or more. Therefore, for example, by making the A / B ratio less than 1.000 in the side margin portion 13 (by making the A / B ratio smaller than that in the effective portion 7), the aforementioned effect achieved by increasing the mole percentage of the additive in the side margin portion 13 can be improved.

[0062] The additives are as follows. Note that the following shows parts by mass when the BT-based particles are 100 parts by mass. The above 100 parts by mass does not include the amount of the additive elements dissolved in the BT-based particles. However, as can be seen from the ranges below, the amount of the additives is relatively small, so the amount of the additives dissolved in the BT-based particles may be included in 100 parts by mass. Also, the following shows the amount of oxide corresponding to the amount of each element, assuming that each element constitutes an oxide.

[0063] (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) (b4) V: 0.01 or more and 0.08 or less (V ２ O ５ Conversion)

[0064] When the above conditions (b1), (b2), (b3) and / or (b4) 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.

[0065] The amount of additive dissolved in the BT-based particles may be the same as or different from that of the other three types of particles (BCT, BST, and BCST). For example, the mass % of the additive contained in the BCT particles may be greater than the mass % of the additive contained in the BT particles. In this case, for example, effects such as an increase in the dielectric constant, a reduction in the temperature dependence of the dielectric constant, improved insulation properties when a high voltage is applied at high temperatures, and improved thermal shock resistance are achieved.

[0066] 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. Furthermore, when aluminum is present as an impurity, the amount of aluminum may be less than 1% by mass of the dielectric.

[0067] (2.4. Difference in mole percentage of additives between multiple regions) As described above, the mole percentage of additives that promote sintering in the side margin portion 13 is greater than the mole percentage in the effective portion 7. As long as this requirement is met, the mole percentage of the additives in each of the effective portion 7 and the side margin portion 13 may be set appropriately.

[0068] For example, the effective portion 7 and the side margin portion 13 may have the same types of additives, with only the mol % being different. Also, the side margin portion 13 may contain additives that are not added to the effective portion 7, thereby promoting sintering more than the effective portion 7. The embodiment in which the mol % of a particular additive in the side margin portion 13 is higher than that in the effective portion 7 includes the embodiment in which the particular additive is not added to the effective portion 7 (the mol % of the effective portion 7 is 0), as described above.

[0069] Furthermore, for example, in an embodiment in which the effective portion 7 and the side margin portion 13 each contain multiple types of common additives, the mole percentages of all types may be high in the side margin portion 13, or some types may be high in the side margin portion 13. For example, in an embodiment in which the effective portion 7 and the side margin portion 13 contain RE, Si, Mg, Mn, and V (and other additives as necessary), in the side margin portion 13, only the mole percentages of RE and Si may be high, the mole percentages of all additives other than Mg may be high, or the mole percentages of all additives including Mg may be high.

[0070] In the above-described embodiment in which the mol % of some types of additives in the side margin portion 13 is higher than that in the effective portion 7, the types selected as the above-described some types are arbitrary. For example, unlike the above examples, only the mol % of Mg may be increased, or only the mol % of Mn and V may be increased.

[0071] For some or all types of additives, the specific value of the ratio and / or difference between the mol % of the side margin portion 13 and the mol % of the effective portion 7 when the mol % of the side margin portion 13 is made higher than the mol % of the effective portion 7 is also arbitrary. These values ​​may be set appropriately depending on the type of additive, etc. In the examples described later, for each of the additives other than Mg (more specifically, RE, Si, Mn, and V), improved thermal shock resistance was obtained when the mol % of the side margin portion 13 was 1.1 to 1.5 times the mol % of the effective portion 7.

[0072] Regarding various values ​​such as ratio, mol %, and mass %, when values ​​are expressed as integers, the digit in the ones place may be regarded as a significant figure unless otherwise specified. When values ​​are expressed as decimals, the digit in the smallest place is a significant figure. Numbers with digits smaller than the significant digit may be rounded up or down. Therefore, for example, 1.1 times or more may include 1.05 times. 1.5 times or less may include 1.54 times.

[0073] It is also possible to set the type and mol% of the additives more flexibly than in the above examples. For example, when all types of additives are considered, the mol% of some types of additives in the side margin portion 13 may be smaller than the mol% in the effective portion 7. Even in this case, the mol% of the remaining types of additives in the side margin portion 13 can be made larger than the mol% in the effective portion 7, thereby making the degree of sintering of the side margin portion 13 and the effective portion 7 closer. In other words, when all types of additives are considered, the mol% may be set so that sintering in the side margin portion 13 is promoted more than sintering in the effective portion 7, ignoring conditions other than the additives (e.g., the influence of the internal electrode 9) (assuming that conditions other than the additives are the same from another perspective).

[0074] The additives (such as their type and mol %) may be the same or different between the side margin portion 13 and the cover portion 15. In either case, the description of the additives in the side margin portion 13 may be applied to the additives in the cover portion 15. For example, the mol % of the additives in the cover portion 15 may be higher than the mol % in the effective portion 7. This allows, for example, the degree of sintering of the cover portion 15 to be closer to the degree of sintering of the effective portion 7, similar to the side margin portion 13, thereby improving thermal shock resistance.

[0075] In determining whether or not the technology disclosed herein has been used, the mol % of the additive may be determined, for example, from the weighing of the additive added to the raw material powder that will become crystal grains 17. However, the mol % of the additive may also be determined by analysis after production. Furthermore, whether or not the technology disclosed herein has been used can be determined if the mol % of the additive can be compared between the effective portion 7 and the side margin portion 13. Therefore, the value of the mol % of the additive itself does not need to be strictly identifiable.

[0076] As is clear from the core-shell structure, the mole percentage of the additive varies between local regions. To eliminate such local influences, the mole percentage of the additive may be determined over a sufficiently wide range or multiple positions within the effective portion 7, the side margin portion 13, or the cover portion 15, averaged, and compared between the regions (7, 13, and 15).

[0077] (3. Manufacturing Method of Capacitor) (3.1. Manufacturing Procedure) The manufacturing method of the capacitor 1 may be various methods, and may be the same as a known method, except that the proportion of the additive is set depending on the portion. An example is shown below.

[0078] FIG. 4 is a flowchart showing an example of the procedure for manufacturing the capacitor 1.

[0079] In step ST1, a first laminate is fabricated. The first laminate is formed by arranging a plurality of portions that will become the laminates 11 along a plane and connecting them to one another. The first laminate is formed by alternately stacking ceramic green sheets, each including a portion that will become a plurality of effective portions 7, and conductive paste that will become a plurality of internal electrodes 9.

[0080] In step ST2, ceramic green sheets including portions that will become multiple cover portions 15 (in other words, ceramic green sheets that overlap almost the entire first laminate) are stacked on the top and bottom surfaces of the first laminate to produce a second laminate.

[0081] In step ST3, the second laminate is singulated (divided) into portions that will become a plurality of capacitors 1 (more precisely, laminates 11 and cover portions 15). The singulation is achieved, for example, by cutting (dicing) using a blade or a laser. At this time, the dividing surfaces (cut surfaces) along the zx plane are the surfaces that will become the side surfaces of the laminate 11 that will be covered by the side margin portions 13. The conductive paste that will become a plurality of internal electrodes 9 is exposed from these cut surfaces. Furthermore, the dividing surfaces (cut surfaces) along the yz plane are the surfaces that will become the side surfaces (end surfaces) of the laminate 11 that will be covered by the external electrodes 5. The conductive paste that will become a plurality of internal electrodes 9 is exposed from these cut surfaces every other layer.

[0082] Any of the side surfaces 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, ground, or other processing after firing, which will be described later, thereby exposing the internal electrode 9 to the outside.

[0083] In step ST4, the ceramic green sheets that will become the side margin portions 13 are attached to the side surfaces along the zx plane of the pieces (the compacts that will become the laminate 11 and cover portion 15) obtained in step ST3. Note that instead of attaching the ceramic green sheets, ceramic material may be disposed on the side surfaces of the compacts by spraying and / or dipping. It may be considered that the ceramic green sheets that will become the side margin portions 13 are formed by this spraying and / or dipping.

[0084] In step ST5, the compact that will become the main body 3 (the laminate 11, the cover 15, and the side margin 13) is fired. In this way, the main body 3 is produced.

[0085] In step ST6, the external electrodes 5 are formed. That is, a metal layer is formed on the side surfaces of the main body 3 along the yz plane.

[0086] A procedure different from the above is one in which step ST4 is omitted and the side margin 13 is formed by the outer edge portion of the ceramic green sheet that will become the effective portion 7. In this embodiment, the compact singulated in step ST3 has portions that will become the laminate 11, the cover portion 15, and the side margin 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.

[0087] In the other procedures in which step ST4 is omitted, the width (length in the y direction) of the side margin portion 13 includes a margin that takes into account positional errors and / or singulation errors of each part in the second laminate into consideration so that the conductive paste that forms 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 consider such a margin. As a result, it is easy to make the side margin portion 13 thinner.

[0088] 4, the effective portion 7 and the side margin portion 13 are produced separately from each other. Therefore, in order to make the mole percentages of the additives different between the effective portion 7 and the side margin portion 13, the mole percentages of the additives in the ceramic green sheets prepared for the effective portion 7 and the side margin portion 13 may be made different from each other.

[0089] (3.2. Manufacturing Method of Dielectric) Hereinafter, a manufacturing method of the dielectric constituting the effective portion 7, the side margin portion 13, and the cover portion 15 will be described.

[0090] As can be understood from the description of Fig. 4, the method for manufacturing a dielectric includes the steps of preparing a ceramic green sheet and firing a molded body prepared using the ceramic green sheet. The ceramic green sheet is prepared by the steps of preparing a ceramic slurry and forming the ceramic slurry into a sheet by an appropriate sheet forming method (e.g., a doctor blade method or a die coater method). The ceramic slurry is prepared, for example, by mixing a raw material powder (e.g., a BT-based powder) that becomes crystal particles 17 (e.g., BT-based particles), an additive (in other words, a sintering aid), and a binder and / or a solvent.

[0091] The description of the composition of the crystal particles 17 (for example, BT-based particles) may be applied to the raw material powder (for example, BT-based powder) as appropriate. ３ The BT powder has a barium titanate-based crystal having a perovskite structure represented by the formula: ３ , Ba １－ｘ Ca ｘTiO ３ , Ba １－ｘ Sr ｘ TiO ３ or Ba １－ｘ－ｙ Ca ｘ Sr ｙ TiO ３ The raw material powder (BT-based powder) has a crystal represented by the formula: Unlike the crystal particles 17 (BT-based particles), the additive is not dissolved in the raw material powder (BT-based powder).

[0092] BT-based powders are produced by mixing and synthesizing compounds containing A-site and B-site elements. At this time, the amounts of the compounds are set so as to obtain the desired composition. For example, in the production of BCT powder, Ba １－ｘ Ca ｘ The ratio of the amount of the Ba-containing compound to the amount of the Ca-containing compound is set so that x in the formula (1) is 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.

[0093] 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 (crystal particles 17). For example, it may be 0.01 μm or more and 0.2 μm or less. Furthermore, the crystallinity of the BT-based powder can be evaluated, for example, by X-ray diffraction, and the index (001)P indicating a tetragonal crystal structure can be obtained. ＡＡ The peak and the index (100) P ＢＢ The ratio of the peak to the peak is P ＡＡ / P ＢＢ may be 1.1 or more.

[0094] The additive may be, for example, an oxide, a carbonate, and / or a glass powder. Specifically, the additive containing Mg, RE, Si, Mn, V, Ca, Sr, and Cr mentioned above may be, for example, MgO (as well as MgCO ３ ), R.E. ２ O ３ , SiO ２ , MnO (in addition to this, MnCO ３ ), V ２ O ５ , CaO, SrO, WO ３ , ZrO ２ and Cr ２ O ３In addition, Li ２ O, B ２ O ３ and BaO may be added.

[0095] The amount of additives (e.g., oxides) containing Mg, RE, Mn, and V 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 described in Section 2.2. Similarly, for other elements, the amount of additives (e.g., oxides) may be set appropriately, for example, so as to realize the mol% in the examples described later.

[0096] Glass powder (e.g., SiO ２ , Li ２ The total amount of the BT-based particles (Li, O, BaO and / or CaO) may be, for example, 0.7 to 2.0 parts by mass relative to 100 parts by mass of the raw material powder that will become the BT-based particles. ２ O is 5 or more and 15 or less, SiO ２ The content of BaO may be 40 or more and 60 or less, BaO may be 10 or more and 30 or less, and CaO may be 10 or more and 30 or less. The content of alumina contained in the glass powder may be 0.1 mass % or less. Addition of such glass powder improves, for example, sinterability.

[0097] Examples of the binder and / or solvent include an organic resin (e.g., polyvinyl butyral resin), toluene, and alcohol. The binder and / or solvent essentially disappears upon firing.

[0098] 5 and 6 are diagrams showing the specifications of capacitors according to examples and comparative examples. These diagrams mainly show examples and comparative examples in which the mole percentages of additives in the effective portion 7, the side margin portion 13, and / or the cover portion 15 are different from one another. They also show that by making the mole percentage of additives in the side margin portion 13 larger than the mole percentage of additives in the effective portion 7, the thermal shock resistance in the side margin portion 13 is improved. Specifically, this is as follows:

[0099] In Figures 5 and 6, the "No." column indicates numbers that identify Examples and Comparative Examples. Numbers with an E (E1 to E12) indicate Examples. Numbers with a C (C1 to C3) indicate Comparative Examples. As can be seen from a comparison of the "No." between Figures 5 and 6, these figures show the same Examples and Comparative Examples. Due to space limitations, Figure 5 shows the configuration of the capacitor (mol % of additives, etc.), and Figure 6 mainly shows the characteristics of the capacitor.

[0100] In Figure 5, the columns "effective portion," "side margin portion," and "cover portion" indicate the mol% of the additives in each portion. The columns "Mg mol%," "RE mol%," "Si mol%," "Mn mol%," and "V mol%" indicate the mol% of the element shown in each column. The column "thickness (μm)" indicates the thickness of the cover portion 15 (thickness t in Figure 3).

[0101] In Fig. 6, the columns "Side margin portion" and "Cover portion" show the ratio of the mole percent of the additives in the side margin portion 13 and the cover portion 15 to the mole percent of the additives in the effective portion 7. The columns "RE+Si ratio," "Other than Mg ratio," and "All ratio" show the ratio of the total mole percent of the combination of elements shown in each column.

[0102] For example, with respect to E1, Fig. 5 shows 0.830 (RE) and 2.500 (Si) as the mole percentages of the additives in the effective portion 7, and 1.000 (RE) and 3.000 (Si) as the mole percentages of the additives in the side margin portion 13. From these values, the "RE+Si magnification" of the side margin portion 13 at E1 in Fig. 6 is calculated as 1.20 (=(1.000+3.000) / (0.830+2.500)) (the calculation result is rounded to two decimal places).

[0103] Here, the "magnification factor other than Mg" is the magnification factor of RE + Si + Mn + V. Here, the "magnification factor of all elements" is the magnification factor of Mg + RE + Si + Mn + V.

[0104] The "Characteristics" column shows the electrical characteristics of the capacitor 1. Specifically, they are as follows:

[0105] In the "Temperature Characteristics" section, "X5R" indicates that the capacitor meets the EIA (Electronic Industries Alliance) X5R standard, but does not meet the X7R standard. "X7R" indicates that the capacitor meets not only the X5R standard, but also the X7R standard. X5R requires that the temperature coefficient of capacitance change from -55°C to 85°C be within ±15% with 25°C as the reference temperature. X7R requires that the temperature coefficient of capacitance change from -55°C to 125°C be within ±15% with 25°C as the reference temperature.

[0106] The "relative dielectric constant" column indicates the relative dielectric constant of the effective portion 7.

[0107] The columns "Thermal Shock SM" and "Thermal Shock CV" show the results of the thermal shock test. More specifically, 500 samples (capacitors) were prepared for each example and comparative example (each number), the capacitor temperature was raised to 350°C, and the number of samples in which cracks occurred was counted. The column "Thermal Shock SM" shows the number of samples in which cracks occurred in the side margin portion 13 (SM: side margin). The column "Thermal Shock CV" shows the number of samples in which cracks occurred in the cover portion 15 (CV: cover). The number of samples in which cracks occurred is shown in fractional form.

[0108] The shape, dimensions, materials, and manufacturing conditions of the capacitors according to the example and comparative example are basically the same, except for the differences shown in Figure 5. Conditions not shown in Figure 5 are as follows: Crystal grains 17: All BCT grains RE: Dy Additives other than those shown in the figure: Zr Thickness of side margin portion 13 (width W in Figure 3): 20 μm

[0109] In the examples, the mol % of at least one type of additive is greater in the side margin portion 13 than in the effective portion 7. Furthermore, the mol % of the side margin portion 13 is greater in the total mol % of all types of additives than in the effective portion 7. On the other hand, in the comparative examples, the mol % of the side margin portion 13 is the same as the mol % of the effective portion 7, with respect to the respective mol % of all types of additives.

[0110] In the comparative example, the "thermal shock SM" was 4 / 500, whereas in the examples, the "thermal shock SM" was 0 / 500 or 2 / 500. From this, it was confirmed that by making the mole percentage of additives in the side margin portion 13 larger than the mole percentage of additives in the effective portion 7, the degree of sintering in the effective portion 7 and the side margin portion 13 can be made closer, thereby improving thermal shock resistance.

[0111] Among the examples, the "thermal shock SM" is 0 / 500 in the cases where the "RE+Si magnification" and / or the "non-Mg magnification" is 1.10 or more and 1.50 or less. The "thermal shock SM" is 2 / 500 in the cases where the "RE+Si magnification" and / or the "non-Mg magnification" is 1.60.

[0112] An example in which the "thermal shock SM" is 2 / 500 shows that if the mole percent ratio of the additive is too large, the thermal shock resistance of the side margin portion 13 actually decreases. The reason for this is that when the firing conditions are matched to those of the effective portion 7, the sintering of the side margin portion 13 proceeds too much. Therefore, the "RE+Si ratio" and / or the "other than Mg ratio" may be set to 1.5 or less.

[0113] The reason why the magnifications shown in Fig. 6 are rounded to one decimal place is to take into consideration the meaning of obtaining a value between 1.50 and 1.60, and practical accuracy, convenience, etc. The same applies to other upper and lower limits described below.

[0114] In several examples, the minimum value of the "RE+Si multiplier" and / or the "multiplier other than Mg" is 1.10. Even in this case, significant effects are demonstrated compared to the comparative examples. Therefore, the multiplier may be set to 1.1 or more. However, as long as the multiplier is larger than unavoidable small errors, the effects of the embodiment are achieved to some extent, so the multiplier does not need to be equal to or greater than the lower limit value.

[0115] While the side margin portion 13 has been described, the same can be said for the cover portion 15. For example, compare E5 to E12 and C2 and C3, which have the same thickness t. In this case, when the "RE+Si multiplier" and / or "non-Mg multiplier" is 1.00 (C2 and C3), the "thermal shock CV" is 3 / 500, whereas when the multiplier is 1.10 or greater and 1.50 or less (E5 to E7, E9 to E11), the "thermal shock CV" is 0 / 500. Therefore, the cover portion 15 also exhibits the same effect as the side margin portion 13. Furthermore, the multiplier may be 1.1 or greater and 1.5 or less.

[0116] In E1 to E4 and C1, the "RE+Si multiplier" and / or "non-Mg multiplier" is 1.00. However, the thickness t of the cover portion 15 is thicker than in the other examples and comparative examples. As a result, the "thermal shock CV" is 0 / 500. From another perspective, E5 to E12 and C2 and C3 show that the cover portion 15 can be made thinner by setting the multiplier of the cover portion 15 to be 1.1 or more and 1.5 or less. This finding can also be applied to the side margin portion 13.

[0117] E1 to E8 (and C1 and C2) and E9 to E12 (and C3) have different mole percentages of Mg in the effective portion 7. As a result, the latter have higher temperature characteristics and lower dielectric constants than the former. Figures 5 and 6 show that even in capacitors with such different temperature characteristics and dielectric constants, thermal shock resistance can be improved by increasing the amount of additives in the side margin portion 13 relatively.

[0118] Examples of the ranges of mol% of additives have already been described. As other examples of the ranges of mol%, the ranges of mol% shown in Figure 5 may be extracted. Specifically, they are as follows. Note that, taking into consideration practical accuracy and / or convenience, the values ​​are rounded to two decimal places. Mg: 0.58 or more and 0.93 or less RE: 0.83 or more and 1.33 or less Si: 2.50 or more and 4.00 or less Mn: 0.25 or more and 0.40 or less V: 0.04 or more and 0.06 or less

[0119] (5. Summary of the 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 (plural) effective portions 7 and (plural) 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). The effective portion 7 and the side margin portion 13 are both made of polycrystalline ceramics. The polycrystalline ceramic contains one or more elements contained in one or more additives that promote sintering (some or all of all types of additives added). The mole percentage of the one or more elements in the side margin portion 13 is greater than the mole percentage of the one or more elements in the effective portion 7.

[0120] From another perspective, a manufacturing method of a multilayer electronic component (capacitor 1) according to an embodiment includes a compacting step (steps ST1 to ST4) and a firing step (step ST5). In the compacting step, a compact (see main body portion 3) is obtained. In the compact (3), a second ceramic green sheet (see side margin portion 13) overlaps a side surface of the laminate (see laminate 11) along the stacking direction (z direction). The laminate (11) includes (plural) first ceramic green sheets (see effective portion 7) and (plural) conductive pastes (see internal electrodes 9) that are alternately stacked. In the firing step, the compact (3) is fired. Both the first and second ceramic green sheets contain one or more additives that promote sintering. The mole percentage of the one or more additives in the second ceramic green sheets is greater than the mole percentage of the one or more additives in the first ceramic green sheets.

[0121] Therefore, for example, as described in the overview of the embodiment, it is easier to sinter the effective portion 7 and the side margin portion 13 in the same manner, thereby improving thermal shock resistance. As a result, for example, it is possible to reduce the width W of the side margin portion 13 without reducing the strength of the side margin portion 13, thereby reducing the size of the capacitor 1 in plan view.

[0122] The polycrystalline ceramic may include barium titanate-based BT-based particles having a perovskite structure. The one or more elements may include one or more rare earth elements (RE) and Si. The total mole percentage of the one or more RE and Si in the side margin portion 13 may be greater than the mole percentage in the effective portion 7.

[0123] In this case, for example, RE and Si are more likely to improve the sinterability of BT-based ceramics than other additives, so the above-mentioned effects can be efficiently achieved by making the mole percentages of RE and Si in the side margin portion 13 higher than those in the effective portion 7.

[0124] The one or more elements may further include Mg. The mole percentage of Mg in the side margin portion 13 may be 1.0 times or more and less than 1.1 times the mole percentage of Mg in the effective portion 7.

[0125] Here, Mg is more likely to promote sintering of BT-based ceramics than RE and Si. This characteristic is generally considered an advantage. However, this characteristic also has the disadvantage that it is difficult to fine-tune the degree of sintering by controlling the amount of Mg added. For example, if the amount of Mg added in the side margin portion 13 is increased compared to the amount of Mg added in the effective portion 7, sintering in the side margin portion 13 may proceed relatively too quickly, potentially reducing the effectiveness of improving thermal shock resistance. Therefore, by making the amount of Mg added in the side margin portion 13 approximately equal to the amount of Mg added in the effective portion 7, as described above, the effect of improving thermal shock resistance is more easily achieved.

[0126] With regard to the total mol % of the one or more elements other than Mg, the mol % in the side margin portion 13 may be 1.1 to 1.5 times the mol % in the effective portion 7 .

[0127] In this case, for example, as described with reference to Figures 5 and 6, it is possible to obtain the effect of improving thermal shock resistance. In addition, it is possible to reduce the possibility that the sintering of the side margin portion 13 progresses relatively too much, which in turn reduces thermal shock resistance.

[0128] The one or more elements may include Mn and V.

[0129] In this case, for example, the types of the one or more elements are closer to those in the examples shown in Figures 5 and 6. Therefore, it is easier to use the knowledge of the examples. Also, for example, in contrast to the above-mentioned Mg, by controlling the amounts of Mn and V added, it is easy to fine-tune the degree of sintering in the side margin portion 13.

[0130] The capacitor 1 may further include a cover portion 15. The cover portion 15 overlaps the surface of the laminate 11 facing the stacking direction (z direction) and may be made of polycrystalline ceramics. The mol % of the one or more elements in the cover portion 15 may be greater than the mol % of the one or more elements in the active portion 7.

[0131] In this case, for example, it becomes easier to bring the degree of sintering of the cover portion 15 closer to the degree of sintering of the effective portion 7 and the side margin portion 13. As a result, the thermal shock resistance of the entire capacitor 1 is improved.

[0132] The one or more elements may include one or more rare earth elements, Si, and Mg. The mole percentage of Mg in the cover portion 15 may be 1.0 times or more and less than 1.1 times the mole percentage of Mg in the effective portion 7. With regard to the total mole percentage of the one or more elements other than Mg, the mole percentage in the cover portion 15 may be 1.1 times or more and 1.5 times or less the mole percentage in the effective portion 7.

[0133] In this case, as described with reference to Figures 5 and 6, it is possible to obtain the effect of improving the thermal shock resistance of the cover part 15. It is also possible to reduce the possibility that the sintering of the cover part 15 progresses relatively too much, which in turn reduces the thermal shock resistance.

[0134] The technology according to the present disclosure is not limited to the above-described embodiments and may be implemented in various forms.

[0135] 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 constitute a capacitor, and other parts of the internal electrodes may constitute an inductor or a resistor. The multilayer electronic component may also constitute an appropriate circuit (e.g., a resonant circuit) as a whole. Furthermore, it is sufficient that at least a part of the multilayer electronic component is constituted by a laminate in which active portions (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 constituted by a laminate.

[0136] From the present disclosure, a concept may be extracted that does not require the mol % of the side margin portion to be greater than the mol % of the effective portion with respect to the mol % of one or more additives. For example, a technical idea may be extracted that is characterized by the mol % of the cover portion being greater than the mol % of the effective portion with respect to the mol % of one or more additives, or a technical idea that the ratio and / or difference between the mol % of the side margin portion and the mol % of the cover portion falls within a predetermined range. In this case, unlike the embodiment, the mol % of the side margin portion may be equal to or less than the mol % of the effective portion. Also, a side margin portion may not be provided.

[0137] 1... capacitor (multilayer electronic component), 7... effective portion, 9... internal electrode, 11... laminate, 13... side margin portion, 15... cover portion, 17... BT-based particles.

Claims

1. A multilayer electronic component comprising: a laminate having alternately overlapping effective portions and internal electrodes; and a side margin portion overlapping a side surface of the laminate along the stacking direction, wherein the effective portion and the side margin portion are both made of polycrystalline ceramics, the polycrystalline ceramics contain one or more elements contained in one or more additives that promote sintering, and the mole percentage of the one or more elements in the side margin portion is greater than the mole percentage of the one or more elements in the effective portion.

2. The multilayer electronic component according to claim 1, wherein the polycrystalline ceramic contains barium titanate-based BT-based particles having a perovskite structure, the one or more elements contain one or more rare earth elements and Si, and the mol % of the total of the one or more rare earth elements and Si in the side margin portion is greater than the mol % in the effective portion.

3. The multilayer electronic component according to claim 2, wherein the one or more elements further include Mg, and the mol % of Mg in the side margin portion is 1.0 times or more and less than 1.1 times the mol % of Mg in the effective portion.

4. The multilayer electronic component according to claim 3, wherein the total mol % of the one or more elements other than Mg in the side margin portion is 1.1 to 1.5 times the mol % in the effective portion.

5. The multilayer electronic component according to claim 4, wherein the one or more elements include Mn and V.

6. A multilayer electronic component according to any one of claims 1 to 5, further comprising a cover portion made of the polycrystalline ceramic and overlapping a surface of the laminate facing the stacking direction, wherein the mol % of the one or more elements in the cover portion is greater than the mol % of the one or more elements in the effective portion.

7. A multilayer electronic component according to claim 6, wherein the one or more elements include one or more rare earth elements, Si, and Mg; the mol % of Mg in the cover portion is 1.0 to less than 1.1 times the mol % of Mg in the effective portion; and with respect to the total mol % of the one or more elements other than Mg, the mol % in the cover portion is 1.1 to 1.5 times the mol % in the effective portion.

8. A method for manufacturing a multilayer electronic component, comprising: a molding step of obtaining a molded body in which a second ceramic green sheet is overlapped on a side along the stacking direction of a laminate having first ceramic green sheets and a conductive paste stacked alternately; and a firing step of firing the molded body, wherein the first ceramic green sheets and the second ceramic green sheets each contain one or more additives that promote sintering, and the mole percentage of the one or more additives in the second ceramic green sheets is greater than the mole percentage of the one or more additives in the first ceramic green sheets.

Images