Electronic component and method for manufacturing electronic component

Abstract

The electronic component has a functional part, a first cover overlapping a first side in a first direction with respect to the functional part, and a second cover overlapping a second side opposite to the first side with respect to the functional part. The first cover has one or more first ceramic layers and one or more first conductor layers alternately overlapping with the one or more first ceramic layers. The second cover has one or more second ceramic layers and one or more second conductor layers alternately overlapping with the one or more second ceramic layers. The configurations of the first cover and the second cover are asymmetric with respect to the functional part.

Description

[Technical field]

[0001] The present disclosure relates to electronic components such as multilayer ceramic capacitors and methods for manufacturing the same. [Background technology]

[0002] Multilayer ceramic capacitors in which ceramic layers and internal electrodes are alternately laminated are known (for example, see Patent Document 1 below). Patent Document 1 discloses a configuration in which a base layer is provided on the upper surface of a functional section consisting of ceramic layers and internal electrodes. Patent Document 1 discloses a problem in which warping occurs in the capacitor due to the sintering shrinkage rate of the ceramic component and the metal component. In Patent Document 1, to solve the above problem, the base layer is made of ceramics containing metal particles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2012 / 043740 Summary of the Invention

[0004] An electronic component according to one embodiment of the present disclosure includes a functional part, a first cover overlapping a first side of the functional part in a first direction, and a second cover overlapping a second side of the functional part opposite to the first side. The first cover includes one or more first ceramic layers and one or more first conductor layers alternately overlapping with the one or more first ceramic layers. The second cover includes one or more second ceramic layers and one or more second conductor layers alternately overlapping with the one or more second ceramic layers. The configurations of the first cover and the second cover are asymmetrical with respect to the functional part.

[0005] A method for manufacturing an electronic component according to an embodiment of the present disclosure includes stacking ceramic green sheets to obtain an unfired laminate, and firing the unfired laminate. The unfired laminate has an unfired functional part, an unfired first cover overlapping a first side of the unfired functional part, and an unfired second cover overlapping a second side of the unfired functional part opposite to the first side. The unfired first cover has one or more layers of first ceramic green sheets and one or more layers of first conductive paste alternately overlapping the one or more layers of first ceramic green sheets. The unfired second cover has one or more layers of second ceramic green sheets and one or more layers of second conductive paste alternately overlapping the one or more layers of second ceramic green sheets. The configuration of the unfired first cover and the configuration of the unfired second cover are asymmetrical with respect to the unfired functional part. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view showing a capacitor according to an embodiment. [Diagram 2] FIG. 2 is a schematic exploded perspective view of the capacitor of FIG. 1. [Diagram 3] FIG. 2 is a cross-sectional view taken along line III-III in FIG. [Figure 4] Schematic diagrams illustrating a method for manufacturing a capacitor. [Diagram 5] 5A to 5C are schematic diagrams illustrating an example of the operation of the embodiment. [Figure 6] 11A and 11B are diagrams showing warpage of capacitors according to a comparative example and an example. [Figure 7] 13A to 13C are diagrams showing warpage of capacitors according to other comparative examples and examples. [Figure 8] 13 is a cross-sectional view showing another example of asymmetry in the up-down direction of a capacitor. FIG. [Figure 9] FIG. 11 is a cross-sectional view showing another example of the arrangement of terminals. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an embodiment according to 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 match the actual ones. In addition, 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 the shapes and / or dimensions may be extracted from the drawings.

[0008] Regarding the aspect described relatively later, basically, only the difference from the aspect described relatively earlier will be described. Matters not specifically mentioned may be the same as the aspect described earlier or may be inferred from the aspect described earlier. For the sake of convenience, the same reference numerals may be used for components corresponding to each other in different aspects, even if there are differences.

[0009] In the description of the embodiments, the term shape may or may not include dimensions. Either interpretation may be used unless a contradiction arises. When referring to a rectangle (or rectangular shape) or a rectangular parallelepiped (or rectangular shape), the corners may be chamfered. Also, relatively small concave or convex portions (not due to error, but intentional) may be formed. The same applies to other shapes. When referring to a certain layer having a constant thickness, there may be variations in thickness due to manufacturing errors (as long as a constant thickness is intended).

[0010] Judgment as to whether various dimensions are within the ranges exemplified in the description of the embodiments (absolute values ​​such as μm or relative values ​​to other dimensions) may be made rationally. For example, the dimensions of the singular portion may be ignored. More specifically, for example, in judging whether the thickness falls within a predetermined range, the chamfered portion may be ignored. Also, for example, in a layer intended to have a constant thickness, when the thickness of the end portion is significantly different (for example, significantly thinner) from the thickness of the majority of the other portions (for example, 60% or more or 80% or more of the area), the thickness of the end portion may be ignored. Also, in the case where there is a variation in thickness in the majority of the specified layer intended to have the above-mentioned constant thickness, for example, an average value may be referenced. It should be noted that, for example, if both the minimum and maximum values ​​of the thickness are within a numerical range, it is of course not necessary to take the trouble to specify and reference the average value.

[0011] With respect to a material (such as a conductive material or an insulating material), the main component may be, for example, a component that occupies 60 wt% or more, 80 wt% or more, or 100 wt% (excluding errors). In the description of the embodiments, the term "main component" may be replaced with the term "component of 60 wt% or more," "component of 80 wt% or more," or "component of 100 wt%," unless a contradiction occurs.

[0012] As the manufacturing process of electronic components progresses, the material composition and microstructure of each part of the electronic component may change. For convenience, the same reference numerals and terms may be used before and after the change.

[0013] (Overview of the embodiment) Fig. 1 is a perspective view showing a capacitor 1 (an example of an electronic component) according to an embodiment. For convenience, a Cartesian coordinate system D1D2D3 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 +D3 side may be regarded as the upper side, and terms such as the upper surface and the lower surface may be used.

[0014] The capacitor 1 is, for example, a multilayer ceramic capacitor. The capacitor 1 has a roughly rectangular parallelepiped body 3 and four external electrodes 5 located at the four corners of the body 3 in a plan view (as viewed in the D3 direction). The external electrodes 5 contribute to electrical connection between the capacitor 1 and other electronic components (for example, a circuit board not shown).

[0015] Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1. Fig. 3 shows a D1D3 cross section taken through the external electrode 5 on the +D2 side. However, the D1D3 cross section taken through the external electrode 5 on the -D2 side, the D2D3 cross section taken through the external electrode 5 on the -D1 side, and the D2D3 cross section taken through the external electrode 5 on the +D1 side are basically the same as Fig. 3. In explaining the embodiments, for convenience, the positional relationship between components may be explained using the terms D1, D2, and D3 without any particular mention, on the basis of the cross section illustrated in Fig. 3.

[0016] For convenience, Fig. 3 shows the boundaries between ceramic layers 11 and dielectric layers 17, which will be described later. However, these boundaries may not be observable. The ceramic layers 11 and the dielectric layers 17 may be identified as different layers based on the fact that they are separated by conductor layers 13 and internal electrodes 19, which will be described later, and the like.

[0017] The main body 3 has, for example, a functional part 7 and two covers 9 (9A and 9B) respectively overlapping the upper and lower surfaces of the functional part 7. The functional part 7 is a portion (at least a part thereof) that directly performs the function of an electronic component (a capacitor in this case). The cover 9 contributes, for example, to protecting the functional part 7 and / or improving the strength of the capacitor 1.

[0018] Of the two covers 9, the cover 9 on the +D3 side is referred to as the first cover 9A, and the cover 9 on the -D3 side is referred to as the second cover 9B. Furthermore, the components of the first cover 9A may be labeled with "first" and "A", such as "first ceramic layer 11A". Similarly, the components of the second cover 9B may be labeled with "second" and "B", such as "second ceramic layer 11B". Furthermore, when there is no particular distinction between the components of the first cover 9A and the second cover 9B, the "first", "second", "A", and "B" may not be used, such as "ceramic layer 11".

[0019] Each cover 9 has one or more ceramic layers 11 (three layers in the illustrated example) and one or more conductor layers 13 (three layers in the illustrated example) that are alternately stacked. Although the term "alternate" is used for convenience, only one ceramic layer 11 and one conductor layer 13 may be provided. The ceramic layer 11 contributes to, for example, insulation of the functional part 7. The conductor layer 13 contributes to, for example, precipitating a metal that becomes the external electrode 5 by a plating method and / or improving the adhesive strength of the external electrode 5 to the main body part 3.

[0020] The configuration of the first cover 9A and the configuration of the second cover 9B are asymmetrical with respect to the functional section 7 (asymmetrical up and down). For example, in the illustrated example, the thickness t1A of the first cover 9A is thicker than the thickness t1B of the second cover 9B. Furthermore, the thickness t3A of the first conductor layer 13A located closest to the +D3 side is thicker than the thickness t3B of the second conductor layer 13B located closest to the -D3 side. Due to such an asymmetrical configuration, for example, as described in detail later, warping that occurs when the laminate that becomes the main body section 3 is fired in the manufacturing process of the capacitor 1 is reduced.

[0021] The above-mentioned effects may not necessarily be achieved. Furthermore, a technical idea different from the above-mentioned viewpoint may be extracted from the present disclosure. In this case, for example, a configuration different from the above description may be adopted. For example, the cover 9 may not include the conductor layer 13.

[0022] The above is an outline of the embodiment. The embodiment will be described below in the following order. 1. Capacitor structure (Figs. 1 to 3) 1.1. Overall structure 1.2. Functional Part 1.3.Cover 1.3.1. Whole cover 1.3.2. Ceramic layer 1.3.3. Conductive Layer (Dummy Electrode and Base Electrode) 1.3.4. Buried structure of base electrode 1.3.5. Examples of vertical asymmetry and dimensions 1.4.External electrode 2. Capacitor manufacturing method (Figure 4) 3. Examples of effects due to asymmetry and particle size (Figure 5) 4. Example (FIGS. 6 and 7) 5. Other embodiments (FIGS. 8 and 9) 5.1. Other examples of asymmetrical top-bottom 5.2. Other examples of terminals 5.3.Other examples of electronic components other than capacitors 6. Summary of the embodiment

[0023] (1. Capacitor structure) (1.1. Overall structure) The capacitor 1 shown in Fig. 1 is configured as, for example, a surface-mounted chip-type component. Specifically, for example, the capacitor 1 is arranged with the -D3 side or +D3 side surface facing a circuit board (not shown). Then, the four pads of the circuit board and the four external electrodes 5 are respectively joined with a conductive joining material (e.g., solder) (not shown) to mount the capacitor on the circuit board.

[0024] The configuration (internal structure and external shape) of the capacitor 1 is, for example, generally rotationally symmetrical by 180° when viewed in the direction D3. Of course, the capacitor 1 does not have to have such symmetry.

[0025] The shape of the main body 3 is, for example, approximately a thin rectangular parallelepiped. The thin shape refers to, for example, that the length in the D3 direction of the main body 3 is shorter than the length in the D1 direction and the length in the D2 direction (for example, the maximum length when the main body 3 is not rectangular). The rectangular parallelepiped may be a square (as shown in the example) or a rectangle (excluding a square; the same applies below) in a plan view. Although not particularly shown, the main body 3 may have relatively large chamfered corners in a plan view and / or a side view. The specific dimensions of the main body 3 (or the capacitor 1) are arbitrary. Specific dimensions of the main body 3 will be exemplified later in the explanation of the specific dimensions of the cover 9.

[0026] As described above, the first cover 9A and the second cover 9B are asymmetric in the up-down direction. However, unless otherwise specified, multiple components of the same type (e.g., 5, 11, 13, 17, and 19, etc.) may basically be provided with the same (or corresponding) shape, size, material, position, etc., as each other. Therefore, unless otherwise specified or unless there is a contradiction, the description of one component may be considered to be common to other components of the same type.

[0027] A layered (membrane-like) component (e.g., 5, 11, 13, 17, and 19) may be entirely made of one type of material. However, a layered component may be made of layers made of different materials. Also, a layered component entirely made of one type of material may be made of one layer, or may be made of a plurality of layers made of the same material stacked together, when focusing on the manufacturing process.

[0028] (1.2. Functional part) The shape of the functional part 7 shown in FIG. 3 is, for example, roughly a thin rectangular parallelepiped. Its planar shape is basically the same as that of the main body 3. The thickness of the functional part 7 is arbitrary. A specific thickness of the functional part 7 will be exemplified later in the explanation of the specific dimensions of the cover 9. The functional part 7 has a roughly symmetrical configuration in the up-down direction. The roughly symmetrical configuration here includes a mode in which the uppermost internal electrode 19 (described below) and the lowermost internal electrode 19 are asymmetrical.

[0029] The functional section 7 has a plurality of alternately overlapping dielectric layers 17 and a plurality of internal electrodes 19. This realizes the function of a capacitor.

[0030] The dielectric layer 17 is basically a layer having a constant thickness (at least between the internal electrodes 19). The shape and dimensions of the dielectric layer 17 in a plan view are basically the same as those of the functional section 7 in a plan view. The thickness of the dielectric layer 17 may be appropriately set according to the characteristics required of the capacitor 1. As an example of a relatively thin thickness, the thickness between the internal electrodes 19 adjacent to each other in the D3 direction may be 0.1 μm or more or 0.5 μm or more, and may be 3.0 μm or less, 2.0 μm or less, or 1.0 μm or less. The above lower limit and upper limit may be combined with any combination. The number of layers of the dielectric layer 17 (internal electrodes 19) is arbitrary. For example, it is 10 layers or more and 30 layers or less. The material of the dielectric layer is, for example, ceramics, and the specific type is also arbitrary.

[0031] The internal electrode 19 is in the form of a layer having a certain thickness. The thickness of the internal electrode 19 is arbitrary, and may be thinner, the same as, or thicker than the thickness of the region between the internal electrodes 19 of the dielectric layer 17. As an example of a relatively thin thickness, the thickness of the internal electrode 19 may be 0.3 μm or more or 0.5 μm or more, and may be 3.0 μm or less, 2.0 μm or less, or 1.0 μm or less. The above lower limit and upper limit may be combined with any one of them. The material (e.g., main component) of the internal electrode 19 is, for example, a metal. The specific type of metal is arbitrary, and for example, the entire metal or the main component is a base metal. The base metal is, for example, Ni or Cu, or an alloy containing at least one of them as a main component. The material of the internal electrode 19 may include ceramics (common material).

[0032] Fig. 2 is an exploded perspective view of the capacitor 1. Fig. 2 is a schematic diagram for understanding the planar shapes and relative positions of the internal electrodes 19, etc. Therefore, Fig. 2 shows a smaller number of various layers than Fig. 3.

[0033] The internal electrode 19 has, for example, a rectangular (square in the illustrated example) electrode body 19a in a plan view, and a pair of extraction electrodes 19b extending from a pair of opposing corners of the electrode body 19a. The specific dimensions of each portion are arbitrary.

[0034] The electrode body 19a is a region where adjacent internal electrodes 19 in the D3 direction overlap each other. The electrode body 19a is located inside the outer edge of the dielectric layer 17, and is not exposed from the side surface of the functional section .

[0035] The pair of extraction electrodes 19b reach the outer edge of the dielectric layer 17, and are connected to a pair of external electrodes 5 located at a pair of opposing corners of the main body 3. The internal electrodes 19 adjacent to each other in the D3 direction are connected to different pairs of external electrodes 5.

[0036] (1.3. Cover) (1.3.1. Entire cover) 3 is, for example, generally layered in shape and size such that it overlaps exactly with the functional portion 7. The thickness of the cover 9 is generally constant.

[0037] As described above, in the illustrated example, the two covers 9 are different from each other in the thickness of the cover 9 and the thickness of the outermost conductor layer 13. In addition to the above differences, in the illustrated example, the thickness of the non-arrangement region (the center side in the D1 direction) of the outermost ceramic layer 11 where the conductor layer 13 is not arranged is also different between the two covers 9. Except for these differences, the configurations of the two covers 9 may be the same as each other.

[0038] (1.3.2. Ceramic Layer) The ceramic layer 11 is a layer having a substantially constant thickness, except for variations in thickness due to the presence or absence of overlap with the conductor layers (13 and 19). The planar shape of the ceramic layer 11 is, for example, basically the same as the planar shape of the dielectric layer 17.

[0039] The number of ceramic layers 11 (or, from another point of view, the number of conductor layers 13) is arbitrary. In the illustrated example, three layers are illustrated, but the number of ceramic layers 11 may be one, two, or four or more.

[0040] The thickness of the ceramic layer 11 is arbitrary. For example, the thickness of the ceramic layer 11 (e.g., between the portions sandwiched between the conductors) may be thicker (in the illustrated example), may be equal to, or may be thinner than the thickness of the dielectric layer 17 (between the internal electrodes 19). Also, for example, the thicknesses of the multiple ceramic layers 11 may be the same as each other or different from each other.

[0041] The material of the ceramic layer 11 is arbitrary. For example, the material of the ceramic layer 11 may be or may not be generally classified as a dielectric. In the former case, the material of the ceramic layer 11 may be the same as or different from the material of the dielectric layer 17. The materials of the multiple ceramic layers 11 may be the same as or different from each other. Examples of ceramics (whole or main component) and dielectrics include barium titanate (BaTiO 3 ), titanium dioxide (TiO 2 ), strontium titanate (SrTiO 3 ), calcium titanate (CaTiO 3 ) and calcium zirconate (CaZrO 3 ) are mentioned.

[0042] (1.3.3. Conductive Layer (Dummy Electrode and Base Electrode)) 2 and 3, each conductor layer 13 has electrodes (21 or 23) located at the four corners in a plan view of the capacitor 1. Here, the electrodes of the outermost conductor layer 13 are referred to as base electrodes 21 (21A and 21B). The electrodes of the other conductor layers 13 are referred to as dummy electrodes 23 (23A and 23B).

[0043] The dummy electrode 23 and the base electrode 21 may have the same configuration, except for the difference in their positions in the D3 direction. Therefore, in this section, for the sake of convenience, the dummy electrode 23 will be described, and the description of the base electrode 21 may be omitted. Unless otherwise specified, or unless a contradiction occurs, the term dummy electrode 23 may be replaced with the term base electrode 21.

[0044] The dummy electrodes 23 are, for example, in the form of a layer having a basically constant thickness. Each dummy electrode 23 is, for example, exposed on a side surface (more specifically, two side surfaces) of the main body 3. The exposed portion of each dummy electrode 23 is fixed to one external electrode 5. Each base electrode 21 constitutes a partial area of ​​the upper surface or lower surface of the main body 3. Each base electrode 21 is fixed to one external electrode 5.

[0045] In a plan view, the position, shape, and size of the dummy electrode 23 are arbitrary. In the illustrated example, the position, shape, and size of the dummy electrode 23 are such that, in a planar perspective view, the dummy electrode 23 overlaps with the external electrode 5 approximately without excess or deficiency (however, the external electrode 5 is slightly wider). The dummy electrode 23 has a rectangular shape (square in the illustrated example) with four sides parallel to the four sides of the rectangular ceramic layer 11 (square in the illustrated example).

[0046] 2 and 3, the dummy electrodes 23 partially overlap with a region (electrode body 19a) where multiple internal electrodes 19 (internal electrodes 19 connected to different external electrodes 5) overlap each other in a planar perspective view. The above region can be said to be a region for ensuring capacitance. The overlapping area between the above region and the dummy electrodes 23 is arbitrary.

[0047] The thickness of the dummy electrode 23 may be, for example, thicker than the thickness of the internal electrode 19 (in the illustrated example), or may be approximately the same as or thinner than the thickness of the internal electrode 19. The thickness of the dummy electrode 23 may be thinner, equal to, or thicker than the thickness of the ceramic layer 11 (for example, the thickness between the electrodes). The thicknesses of one or more dummy electrodes 23 and the base electrode 21 may be the same as each other or different from each other. In the illustrated example, the thicknesses of the multiple dummy electrodes 23 are the same as each other. The thicknesses of the base electrodes 21 (t3A and t3B, respectively) are made thicker than the thickness of the dummy electrodes 23.

[0048] The material of the dummy electrode 23 is arbitrary. For example, the material of the dummy electrode 23 may be the same as or different from the material of the internal electrode 19. In any case, the description of the material of the internal electrode 19 may be applied to the material of the dummy electrode 23.

[0049] (1.3.4. Buried Structure of Base Electrode) 3, the first base electrode 21A is embedded from above into the outermost first ceramic layer 11A. Furthermore, the upper surface of the first base electrode 21A is flush with the upper surface of the outermost first ceramic layer 11A (here, the upper surface of the region where the first base electrode 21A is not disposed; the same applies hereinafter in this section).

[0050] When referring to being flush, for example, the difference in position in the D3 direction between the upper surface of the first base electrode 21A and the upper surface of the first ceramic layer 11A may be 20% or less, 10% or less, or 5% or less of the thickness of the base electrode 21. Note that the position of the upper surface may be specified rationally as described above, and may be, for example, an average value excluding unique portions such as ends, or may be expressed by the distance from a reference surface (flat or curved) taking warping into consideration (the same applies to the position of the lower surface below).

[0051] Considering the case where the upper surface of the first base electrode 21A and the upper surface of the outermost first ceramic layer 11A are not flush with each other, the embedding amount of the former with respect to the latter is arbitrary. The embedding amount is, for example, the distance from the position of the upper surface of the outermost first ceramic layer 11A to the position of the lower surface of the first base electrode 21A. For example, the embedding amount may be less than 50% of the thickness of the base electrode 21, may be 50% or more, or may be 80% or more.

[0052] The first base electrode 21A may be embedded in the outermost first ceramic layer 11A by any method. For example, the outermost first ceramic layer 11A may be formed by two layers of ceramic green sheets. A conductive paste that will become the first base electrode 21A is placed on the upper surface of the lower ceramic green sheet of the two layers, and a hole (notch) is provided in the upper ceramic green sheet of the two layers in the region where the first base electrode 21A is located. Alternatively, in addition to or instead of such a method, the first base electrode 21A may be embedded in the outermost first ceramic layer 11A by pressing the conductive paste applied to the upper surface of the ceramic green sheet.

[0053] Although the first base electrode 21A has been taken as an example, the second base electrode 21B is similar. The above description may be applied to the second base electrode 21B by replacing the words "first", "A" and "upper" with the words "second", "B" and "lower". Also, unlike the illustrated example, the base electrode 21 does not have to be embedded in the outermost ceramic layer 11.

[0054] (1.3.5. Examples of vertical asymmetry and dimensions) As described above, the configuration of the first cover 9A and the configuration of the second cover 9B are asymmetric with respect to the functional section 7. Note that the asymmetry referred to here does not include asymmetry due to unintended manufacturing errors. For example, even if the capacitor 1 undergoes unintended warping during firing, which causes the first cover 9A and the second cover 9B to be asymmetric in the up-down direction, this does not fall under the asymmetry referred to here.

[0055] In the example of Fig. 3, as described above, the thickness t1A of the first cover 9A is thicker than the thickness t1B of the second cover 9B, and the thickness t3A of the first base electrode 21A is thicker than the thickness t3B of the second base electrode 21B. In this case, the specific values ​​of the thicknesses t1A, t1B, t3A, and t3B are arbitrary. The specific values ​​of these thicknesses and the values ​​of various dimensions other than these thicknesses are exemplified below.

[0056] The dimensional ranges shown below are merely examples, and values ​​outside the ranges shown below may be used. Also, examples of different dimensional values ​​may be combined with any other values. For example, examples of the thickness of the main body 3 and the thickness of the cover 9 may be combined with any other values. The specific values ​​shown below may be used in other aspects (e.g., t1A=t1B and / or t3A=t3B) as described below, unless a contradiction occurs. The specific values ​​shown below may be values ​​that take into account aspects other than the illustrated example (e.g., an aspect in which the dummy electrode 23 is not provided).

[0057] The lengths of the main body 3 (or the capacitor 1) in the D1 and D2 directions may be 300 μm or more or 400 μm or more, and may be 2000 μm or less, 1000 μm or less, or 700 μm or less. Any combination of the above lower and upper limits may be used. The thickness of the main body 3 in the D3 direction may be 30 μm or more or 50 μm or more, and may be 500 μm or less, 200 μm or less, or 100 μm or less. Any combination of the above lower and upper limits may be used.

[0058] The thickness of the functional portion 7 may be 30% or more, 40% or more, 50% or more, 60% or more, or 70% or more, and may be 90% or less, 80% or less, or 70% or less, of the thickness of the main body portion 3. The above lower limit and upper limit may be arbitrarily combined as long as no contradiction occurs.

[0059] The boundary between the functional portion 7 and the cover 9 may be determined rationally. For example, when the material of the dielectric layer 17 is the same as the material of the ceramic layer 11, the +D3 side surface of the internal electrode 19 located closest to the +D3 side and the -D3 side surface of the internal electrode 19 located closest to the -D3 side may be specified as the upper and lower surfaces of the functional portion 7.

[0060] The thickness (t1A or t1B) of each cover 9 may be 5% or more, 10% or more, or 15% or more, and may be 35% or less, 30% or less, 25% or less, 20% or less, or 15% or less, relative to the thickness of the main body 3. The above lower limit and upper limit may be combined with any of the above as long as no contradiction occurs. The thickness (t1A or t1B) of each cover 9 may be 5 μm or more, 10 μm or more, or 15 μm or more, and may be 50 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. The above lower limit and upper limit may be combined with any of the above as long as no contradiction occurs.

[0061] The difference in thickness (t1A-t1B) of the cover 9 may be 5% or more, 10% or more, or 15% or more, and 40% or less, 30% or less, or 20% or less, relative to the thickness t1B of the second cover 9B. The above lower limit and upper limit may be combined with any of the above. The difference in thickness (t1A-t1B) of the cover 9 may be 0.5 μm or more, 1.0 μm or more, or 1.5 μm or more, and 4.0 μm or less, 3.0 μm or less, or 2.5 μm or less. The above lower limit and upper limit may be combined with any of the above. The ratio (t1A / t1B) of the thickness of the first cover 9A to the thickness of the second cover 9B may be 1.05 or more, 1.10 or more, or 1.15 or more, and 1.40 or less, 1.30 or less, or 1.25 or less. The above lower and upper limits may be combined in any combination.

[0062] The thickness of each base electrode 21 (t3A or t3B) may be 10% or more, 20% or more, 30% or more, or 40% or more of the thickness of the cover 9 to which it belongs, and may be 90% or less, 60% or less, 50% or less, or 40% or less. The above lower limit and upper limit may be combined with any of the above so as not to cause a contradiction. The thickness of each base electrode 21 (t3A or t3B) may be 1.0 μm or more, 2.0 μm or more, 3.0 μm or more, or 5.0 μm or more, and may be 20.0 μm or less, 10.0 μm or less, or 5.0 μm or less. The above lower limit and upper limit may be combined with any of the above so as not to cause a contradiction.

[0063] An example of the thickness difference (t3A-t3B) of the base electrode 21 may be the same as the example of the thickness difference (t1A-t1B) of the cover 9 described above. The thickness difference (t3A-t3B) of the base electrode 21 may be 20% or more, 30% or more, 50% or more, or 80% or more, and may be 200% or less, 150% or less, 100% or less, or 80% or less, with respect to the thickness t3B of the second base electrode 21B. The above lower limit and upper limit may be combined with any combination so long as no contradiction occurs. The ratio (t3A / t3B) of the thickness of the first base electrode 21A to the thickness of the second base electrode 21B may be 1.2 or more, 1.4 or more, or 1.5 or more, and may be 2.5 or less, 2.0 or less, or 1.8 or less. The above lower limit and upper limit may be combined with any combination.

[0064] The following ranges can be exemplified as thickness ranges close to the thicknesses of the cover 9 and the base electrode 21 in the examples described later. Thickness t1A of the first cover 9A: 10μm to 16μm Thickness t1B of second cover 9B: 8 μm or more and 14 μm or less Thickness t3A of the first base electrode 21A: 4 μm or more and 8 μm or less Thickness t3B of the second base electrode 21B: 2 μm or more and 6 μm or less However, t1A>t1B and t3A>t3B.

[0065] The length of each base electrode 21 in the D1 direction may be, for example, 10% or more, 20% or more, or 30% or more, or 45% or less, 40% or less, or 30% or less, relative to the length of the main body 3 in the D1 direction. The above lower limit and upper limit may be combined with any of them so as not to cause any contradiction. Also, for example, the length of each dummy electrode 23 in the D1 direction may be 50 μm or more, 100 μm or more, or 150 μm or more, or 500 μm or less, 300 μm or less, or 200 μm or less. The above lower limit and upper limit may be combined with any of them. Although an example of the length in the D1 direction is given, the length may be applied to the length in the D2 direction. Also, the example of the dimensions of the base electrode 21 in this paragraph may be applied to the dummy electrode 23.

[0066] The thickness of each dummy electrode 23 may be 5% or more, 10% or more, or 20% or more of the thickness of the cover 9 to which it belongs, and may be 50% or less, 30% or less, or 20% or less. The above lower limit and upper limit may be combined with any one of them so as not to cause a contradiction. For example, the thickness of the dummy electrode 23 may be 0.3 μm or more, 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more, and may be 10.0 μm or less, 5.0 μm or less, 3.0 μm or less, or 2.0 μm or less. The above lower limit and upper limit may be combined with any one of them so as not to cause a contradiction.

[0067] The thickness of each ceramic layer 11 (e.g., between electrodes) may be 5% or more, 10% or more, or 20% or more of the thickness of the cover 9 to which it belongs, and may be 50% or less, 30% or less, or 20% or less. The above lower limit and upper limit may be combined with any combination so long as no contradiction occurs. The thickness of each ceramic layer 11 (e.g., between electrodes) may be 1.0 μm or more, or 2.0 μm or more, and may be 10.0 μm or less, or 5.0 μm or less. The above lower limit and upper limit may be combined with any combination.

[0068] (1.4.External electrode) The external electrode 5 is, for example, a layer having a basically constant thickness. As shown in FIG. 1, the external electrode 5 covers, for example, roughly the four faces (upper face, lower face, and two side faces) of the main body 3 at the corners of the main body 3 in a plan view. This allows one external electrode 5 to be connected to one extraction electrode 19b at two side faces of the main body 3, and also allows surface mounting on either the upper face or the lower face of the capacitor 1. As described above, the external electrode 5 is fixed to the exposed part of the conductor layer 13 from the cover 9. Furthermore, the external electrode 5 is also fixed to the ceramic layer 11 and the dielectric layer 17. The shape and size of the parts on each face of the external electrode 5 are arbitrary.

[0069] The thickness of the external electrode 5 is arbitrary. For example, the thickness of the external electrode 5 may be thicker than the thickness of the internal electrode 19, the dummy electrode 23, and the base electrode 21. For example, the thickness of the external electrode 5 may be 1.2 times or more, 2 times or more, or 3 times or more, or 10 times or less, 5 times or less, or 3 times or less, of the thickness (t3A or t3B) of the base electrode 21. The above lower limit and upper limit may be combined with any of them. Also, for example, the thickness of the external electrode 5 may be 3 μm or more, 5 μm or more, or 10 μm or more, or 30 μm or less, 20 μm or less, or 10 μm or less. The above lower limit and upper limit may be combined with any of them so long as no contradiction occurs.

[0070] The material of the external electrode 5 is, for example, a metal. The specific type of metal is arbitrary, and for example, the entirety or main component thereof is a base metal (for example, Ni and / or Cu). The external electrode 5 may be formed by laminating different materials as necessary. For example, the external electrode 5 may be formed by laminating Cu, Ni, and Sn from the base electrode 21 side. The material of the external electrode 5 may be the same as or different from the material (for example, main component) of the internal electrode 19, the dummy electrode 23, and / or the base electrode 21. The external electrode 5 may be formed so as not to contain the same material (common material) as the material (for example, main component) of the ceramic layer 11.

[0071] As indicated by the symbols in Figure 3, in the description of the embodiment, the portion of the external electrode 5 covering the first cover 9A (at least a part of it) may be referred to as the first external electrode 5a, and the portion of the external electrode 5 covering the second cover 9B (at least a part of it) may be referred to as the second external electrode 5b.

[0072] (2. Capacitor manufacturing method The capacitor 1 may be manufactured by various methods. For example, the capacitor 1 may be manufactured by a known method, except for the specific dimensions. An example of the manufacturing method is shown below.

[0073] Fig. 4 is a schematic diagram showing a manufacturing method. The left side of Fig. 4 shows a manufacturing method of a capacitor according to a comparative example (more specifically, a body portion 3Z). The right side of Fig. 4 shows a manufacturing method of a capacitor 1 according to an embodiment (more specifically, a body portion 3).

[0074] First, prepare ceramic green sheets that will become the dielectric layers 17 and the ceramic layers 11. Next, apply (for example, print) a conductive paste that will become the internal electrodes 19, dummy electrodes 23, or base electrodes 21 to the ceramic green sheets.

[0075] Next, as shown in the first to third rows from the top of FIG. 4, the ceramic green sheets are laminated to prepare a laminate (main body 3 in an unfired state) that will become the main body 3 (3Z). The order of lamination at this time is arbitrary. In the illustrated example, the ceramic green sheets are laminated one by one starting from the lower (second cover 9B side) ceramic green sheet. Unlike the illustrated example, for example, the ceramic green sheets may be laminated one by one starting from the upper (first cover 9A side) ceramic green sheet, and / or several laminated sheets may be stacked on top of each other.

[0076] As already mentioned, one ceramic layer 11 may be composed of two or more ceramic green sheets. As can be understood from this, when the ceramic green sheets and the conductive paste are alternately stacked, the ceramic green sheets and the conductive paste do not have to be alternately stacked one layer at a time. However, like the ceramic layer 11, ceramic green sheets stacked without any conductive paste in between may be regarded as one layer.

[0077] The above-mentioned process up to the production of the laminate is performed, for example, on a mother substrate having a size from which a large number of main body parts 3 are obtained. After the production of the laminate, the mother substrate including the laminate is diced (e.g., cut) into pieces having a size roughly corresponding to the size of the main body parts 3.

[0078] Next, as shown in the third row from the top of Fig. 4, a laminate having the size of the main body 3 is fired. Any firing method can be used. In the illustrated example, an electric furnace 25 is shown as a schematic. Alternatively, for example, firing may be performed by irradiating the laminate with microwaves.

[0079] Before firing, degreasing may be performed. The firing may be performed, for example, in a reducing atmosphere. After firing, a reoxidation heat treatment may be performed. Before and / or after firing, polishing (e.g., barrel polishing) of the main body portion 3 may be performed. In the polishing, for example, the ridges of the main body portion 3 may be chamfered or the side surfaces of the main body portion 3 may be polished.

[0080] After firing the main body 3, the external electrode 5 is formed. The external electrode 5 may be formed by various methods. For example, metal may be deposited on the surface (upper or lower surface, and side surface) of the base electrode 21, the exposed portion of the dummy electrode 23 from the side surface of the main body 3, and the exposed portion of the internal electrode 19 from the side surface of the main body 3 by electroless plating and / or electrolytic plating. Also, a thin film formation method such as a dipping method, a printing method, CVD (Chemical Vapor Deposition) or PVD (Physical Vapor Deposition) may be adopted. As understood from the above, the base electrode 21, the dummy electrode 23, and the internal electrode 19 may or may not contribute to the deposition of metal.

[0081] In the main body 3Z according to the comparative example, unlike the main body 3 according to the embodiment, the first cover 9A and the second cover 9B have the same thickness, and the first base electrode 21A and the second base electrode 21B have the same thickness. As shown in the bottom left of Fig. 4, the main body 3Z is prone to warping with a concave upper portion during firing.

[0082] The causes of warping include, for example, the following. In the process of stacking ceramic green sheets, a relatively low-pressure press is performed each time a ceramic green sheet is stacked. This press contributes, for example, to pressure-bonding the ceramic green sheets together. The lower the ceramic green sheets are, the more times they are pressed, and the higher the density of the ceramic particles. Conversely, the higher the ceramic green sheets are, the lower the density of the ceramic particles. As a result, the degree of shrinkage is greater at the top during sintering. As a result, the compressive stress in the direction along the layers is greater at the top, and warping occurs with the top concave.

[0083] As described above, in this disclosure, when determining whether or not there is asymmetry between the configuration of the first cover 9A and the configuration of the second cover 9B with respect to the functional part 7, asymmetry due to unintended manufacturing errors is not included. The above-mentioned differences in the stacking order and density of ceramic particles due to pressing are manufacturing errors. Therefore, even if the first cover 9A and the second cover 9B differ in terms of the microstructure after firing due to differences in density before firing (even if such a prior art exists), it is determined that the asymmetry referred to here does not exist.

[0084] (3. Examples of Effects Due to Asymmetry and Examples of Particle Sizes) 4, the main body 3 according to the embodiment has less warping due to firing than the main body 3Z according to the comparative example, for example, the reason being as follows.

[0085] FIG. 5 is a schematic diagram illustrating an example of why warping is reduced by making the first base electrode 21A thicker than the second base electrode 21B.

[0086] In Fig. 5, the upper part shows metal particles 27 contained in the conductive paste (base electrode 21) and an organic layer 29 made of a binder or the like. The lower part shows ceramic particles 31 contained in the ceramic green sheet (ceramic layer 11) and an organic layer 33 made of a binder or the like. In Fig. 5, the left side shows the state before firing, and the right side shows the state after firing.

[0087] In general, the particle diameter of the metal particles 27 is larger than the particle diameter of the ceramic particles 31. Furthermore, the same material or similar materials are often used for the organic layers 29 and 33. Even if the particle diameters of the metal particles 27 and the ceramic particles 31 are different from each other, the thicknesses t7 of the organic layers 29 and 33 are generally the same.

[0088] Therefore, in the conductive paste, the surface area of ​​the particles relative to the volume of the particles is smaller than that of the ceramic green sheet, and therefore the volume of the organic matter relative to the volume of the particles is smaller. When the organic matter is lost by firing, the volume ratio of the lost organic matter is smaller in the conductive paste than in the ceramic green sheet. As a result, the degree of shrinkage of the conductive paste is smaller than that of the ceramic green sheet.

[0089] 3, the first base electrode 21A is thicker than the second base electrode 21B, so that the volume ratio of the conductive paste in the first cover 9A before firing is greater than the volume ratio of the conductive paste in the second cover 9B before firing. As a result, the amount of shrinkage in the direction along the layers of the first cover 9A is smaller than the amount of shrinkage in the direction along the layers of the second cover 9B. As a result, upward concave warpage of the main body 3 is reduced.

[0090] When the first cover 9A is made thicker than the second cover 9B, intuitively, it would seem that the compressive force (compressive stress of the first cover 9A×thickness of the first cover 9A) applied by the first cover 9A to the functional portion 7 would increase in proportion to the increase in thickness, promoting upwardly concave warping. However, in reality, as explained in the estimated mechanism above and as shown in the examples described below, warping is reduced. Thus, the capacitor 1 according to the embodiment produces an effect contrary to intuitive expectation, and is revolutionary.

[0091] Although not shown in Fig. 5, the metal particles 27 and ceramic particles 31 grow during firing. However, because the difference in diameter between the two is relatively large, the size relationship before firing is usually maintained after firing. Therefore, it is possible to determine whether the above-mentioned effect has occurred from the size of the particles after firing.

[0092] The specific particle diameters of the metal particles and ceramic particles are arbitrary. For example, the average particle diameter of the metal particles contained in the conductive paste that will become the base electrode 21 and the dummy electrode 23 may be 100 nm or more and 500 nm or less, or 180 nm or more and 370 nm or less. The average particle diameter of the metal particles contained in the conductive paste that will become the internal electrode 19 may be 50 nm or more and 200 nm or less. The average particle diameter of the ceramic particles contained in the ceramic green sheets that will become the dielectric layer 17 and the ceramic layer 11 may be 20 nm or more and 80 nm or less. The average particle diameter of the metal particles contained in the conductive paste that will become the base electrode 21 and the dummy electrode 23 may be 2 times or more, 5 times or more, or 8 times or more than the average particle diameter of the ceramic particles contained in the ceramic green sheets that will become the ceramic layer 11 and the dielectric layer 17.

[0093] For example, the average particle diameter of the metal particles (after firing) of the base electrode 21 and the dummy electrode 23 may be 200 nm or more and 800 nm or less, or 350 nm or more and 400 nm or less. The average particle diameter of the metal particles (after firing) contained in the internal electrode 19 may be 100 nm or more and 300 nm or less, or 150 nm or more and 200 nm or less. The average particle diameter of the ceramic particles (after firing) contained in the dielectric layer 17 and the ceramic layer 11 may be 50 nm or more and 150 nm or less, or 70 nm or more and 80 nm or less. The average particle diameter of the metal particles (after firing) contained in the base electrode 21 and the dummy electrode 23 may be 2 times or more, 5 times or more, or 8 times or more than the average particle diameter of the ceramic particles contained in the ceramic layer 11 and the dielectric layer 17.

[0094] In addition, the ratio of the organic material to the metal particles or ceramic particles before firing is also arbitrary. For example, in the conductive paste that becomes the base electrode 21, the dummy electrode 23, and the internal electrode 19, when the parts by mass of the metal particles are taken as 100, 10 parts by mass or more and 40 parts by mass or less of the organic material may be mixed. In addition, in the ceramic green sheets that become the ceramic layer 11 and the dielectric layer 17, when the parts by mass of the ceramic particles are taken as 100, 10 parts by mass or more and 40 parts by mass or less of the organic material may be mixed.

[0095] 4. Working Examples The capacitor bodies according to the comparative example and the example were fabricated and their warpage was measured. As a result, it was confirmed that the warpage was reduced in the example compared to the comparative example. Specifically, it is as follows.

[0096] As described below, comparative examples and examples having different configurations regarding symmetry in the up-down direction were set. Comparison Example 1: Top-bottom symmetrical capacitor Comparative Example 2: A capacitor in which the second cover 9B and the second base electrode 21B are thickened in the comparative example 1. Example: A capacitor in which the first cover 9A and the first base electrode 21A are thickened in Comparative Example 1. In the comparative examples and examples, matters not specifically mentioned are the same as those of the capacitor 1 of the embodiment.

[0097] The above Comparative Example 1, Comparative Example 2, and Example were set for capacitor bodies having different reference sizes. For convenience, Comparative Example 1, Comparative Example 2, and Example may be referred to as follows, with "A" or "B" added to them. Comparative Example 1A, Comparative Example 2A and Example A: Size A Comparative Example 1B, Comparative Example 2B and Example B: Size B

[0098] Sizes A and B are as follows: Size A: 600μm (D1 direction) x 600μm (D2 direction) x 90μm (D3 direction) Size B: 500μm (D1 direction) x 500μm (D2 direction) x 65μm (D3 direction) These sizes are design values ​​for the main body (after firing) of the capacitor according to Comparative Example 1.

[0099] The thicknesses of the cover 9 and the base electrode 21 according to the comparative example and the example are as follows. Thickness of each cover 9 in Comparative Example 1, thickness of the first cover 9A in Comparative Example 2, and thickness of the second cover 9B in the embodiment: 10 μm Thickness of the second cover 9B in Comparative Example 2 and the first cover 9A in the Example: 12 μm Thickness of each base electrode 21 in Comparative Example 1, thickness of the first base electrode 21A in Comparative Example 2, and thickness of the second base electrode 21B in the embodiment: 3 μm Thickness of the second base electrode 21B in Comparative Example 2 and the first base electrode 21A in the Example: 5 μm The thicknesses of the cover 9 and the base electrode 21 are common to sizes A and B, and are design values ​​after firing.

[0100] The average particle sizes of the metal particles and ceramic particles before and after firing are within the ranges exemplified above (the narrower range when two or more ranges are shown). The material of the metal particles contained in the conductive pastes (13 and 19) was Ni. The material of the ceramic particles contained in the ceramic green sheets (11 and 17) was BaTiO 3It was stated that.

[0101] The warpage was evaluated as follows. As shown in the bottom left of Fig. 4, the difference between the lowest point on the top surface and the highest point on the top surface was measured as the amount of warpage WP. WP was divided by the thickness T of the main body 3 and multiplied by 100 to obtain the unit of %. For each of the comparative example and the example, multiple (10) samples were produced, and the frequency distribution of WP / T x 100 (%) was examined.

[0102] 6 and 7 are diagrams showing the above evaluation results. In these diagrams, the horizontal axis indicates the above WP / T×100(%). The vertical axis indicates the number of samples. FIG. 6 corresponds to the comparative example and the embodiment of size A. FIG. 7 corresponds to the comparative example and the embodiment of size B. In each diagram, the upper row corresponds to comparative example 1, the middle row corresponds to comparative example 2, and the lower row corresponds to the embodiment.

[0103] As shown in these figures, the probability of large warpage is higher in Comparative Example 2 than in Comparative Example 1. On the other hand, the probability of small warpage is higher in the Examples than in Comparative Example 1.

[0104] More specifically, in size A (FIG. 6), there are no samples in Comparative Example 1A with a warpage of 9% or less, whereas all samples in Example A have a warpage of 9% or less. In addition, in size B (FIG. 7), there is only one sample in Comparative Example 1B with a warpage of 9% or less, whereas all samples in Example B have a warpage of 9% or less.

[0105] (5. Other Aspects) (5.1. Other examples of asymmetric top and bottom) 8 is a cross-sectional view showing another example of the asymmetry between the two covers 9. The above-mentioned example of the asymmetry (asymmetry in the thickness of the covers 9 and / or the base electrode 21) and the following other examples may be arbitrarily combined with each other.

[0106] In the main body 3A shown in the top row of Fig. 8, the length L1A of the first conductor layer 13A is longer than the length L1B of the second conductor layer 13B in a given cross section. This increases the volume ratio of the conductive paste in the first cover 9A before firing, for example. As a result, warping with a concave upward shape is reduced by a mechanism similar to that in the case where the first base electrode 21A is made thicker.

[0107] As shown in this example, the asymmetry in the up-down direction may be realized by a difference in the configurations of the first conductor layer 13A and the second conductor layer 13B in the left-right direction. The specific difference and ratio between the length L1A and the length L1B are arbitrary. The objects having different configurations in the left-right direction may be arbitrary, and may be, for example, the base electrode 21 and / or some or all of the dummy electrodes 23.

[0108] 8, the thickness t9A of the first dummy electrode 23A is made thicker than the thickness t9B of the second dummy electrode 23B. This reduces upwardly concave warpage due to a mechanism similar to that in the case where the first base electrode 21A is made thicker.

[0109] In the illustrated example, only one dummy electrode 23 is shown in each cover 9. When the number of dummy electrodes 23 in each cover 9 is two or more, t9A>t9B may be true for all the dummy electrodes 23, or may be true for only some of the dummy electrodes 23. The specific difference and ratio between the thicknesses t9A and t9B are arbitrary. The explanation of the difference and ratio between the thicknesses t3A and t3B of the base electrode 21 may be applied to the difference and ratio between the thicknesses t9A and t9B.

[0110] 8, the number of first conductor layers 13A (first dummy electrodes 23A) is greater than the number of second conductor layers 13B (second dummy electrodes 23B). This increases the volume ratio of the conductive paste in the first cover 9A before firing, for example, and reduces upwardly concave warpage due to a mechanism similar to that in the case where the first base electrode 21A is made thicker.

[0111] In the illustrated example, the difference in the number of layers between first dummy electrode 23A and second dummy electrode 23B is 1. However, the difference in the number of layers between the two may be 2 or more. In addition, the ratio of the number of layers of first dummy electrode 23A to the number of layers of second dummy electrode 23B (2 times in the illustrated example) is also arbitrary.

[0112] In the main body 3D shown in the bottom of Fig. 8, the average particle diameter of the ceramic particles 31A in the ceramic green sheet that becomes the first cover 9A is made larger than the average particle diameter of the ceramic particles 31B in the ceramic green sheet that becomes the second cover 9B. As can be understood from the explanation of Fig. 5, in this case, the degree of shrinkage of the first cover 9A is smaller than that in the case where the ceramic particles 31B are used instead of the ceramic particles 31A. As a result, the warp with a concave upward shape is reduced.

[0113] In the illustrated example, the average particle size of the ceramic particles is made different between first cover 9A and second cover 9B. Instead of or in addition to the average particle size of the ceramic particles, the average particle size of the metal particles in conductor layer 13 may be made different between first cover 9A and second cover 9B. The difference and ratio of the average particle sizes are arbitrary.

[0114] Although not particularly shown, the solid content ratio in the ceramic green sheet and / or conductive paste of the first cover 9A may be made higher than that of the second cover 9B to reduce upwardly concave warping. Also, the proportion of common material (ceramic particles) contained in the conductive paste of the first cover 9A may be made lower than that of the second cover 9B to reduce upwardly concave warping.

[0115] As can be seen from Figure 3 and the examples from the first to third rows from the top of Figure 8, the asymmetry in the vertical direction may be achieved by making the volume fraction of the conductor layer 13 (unfired conductive paste) in the first cover 9A greater than that in the second cover 9B.

[0116] Furthermore, as can be seen from the examples in Figure 3 and the second and third rows from the top of Figure 8, the asymmetry in the vertical direction may be achieved by making the total thickness of the conductor layer 13 (unfired conductive paste) in the first cover 9A thicker than that in the second cover 9B.

[0117] In the first cover 9A and the second cover 9B, layers that are the same in number (11 or 13) from the functional section 7 are referred to as corresponding layers. In this case, as can be understood from the examples from the second row from the top to the bottom row in Fig. 3 and Fig. 8, the asymmetry in the vertical direction may be realized by making at least one of the thicknesses of the corresponding layers, the materials of the corresponding layers, and the number of conductor layers 13 different from each other. Note that when the total number of conductor layers 13 differs between the first cover 9A and the second cover 9B, the corresponding layers between the first cover 9A and the second cover 9B do not need to be specified.

[0118] 3 and 8, the thickness of the first cover 9A (from another point of view, the thickness of the first ceramic layer 11A in the area where the first conductor layer 13A is not disposed) is increased in accordance with the increase in the thickness of the first conductor layer 13A. However, the thickness of the first cover 9A may be the same as the thickness of the second cover 9B, while the first conductor layer 13A is made thicker than the second conductor layer 13B.

[0119] (5.2. Other examples related to terminals) Fig. 9 is a perspective view of another example of capacitor 201. Fig. 3 may be referred to as a view showing a D1D3 cross section of capacitor 201 (main body portion 203).

[0120] Generally speaking, capacitor 201 differs from capacitor 1, which is a four-terminal type, in that it is a two-terminal type. The above-described asymmetry in the vertical direction may be applied to capacitor 201. Although not shown in the figure, asymmetry in the vertical direction may also be applied to capacitor 1 of other terminal types, such as a three-terminal type.

[0121] (5.3. Other examples of electronic components other than capacitors) Although not specifically shown, further configurations will be described.

[0122] The capacitor may have an exterior resin covering the entire structure illustrated in FIG. 1 or 9, and lead wires connected to the external electrodes 5 and extending from the exterior resin. From another perspective, the capacitor may be a through-hole mount type rather than a surface mount type. In such an embodiment, one external electrode 5 may only cover one side surface. The capacitor may be distributed from one factory to another factory without the external electrodes 5 (i.e., the main body 3).

[0123] Two types of internal electrodes 19 connected to different external electrodes 5 may be alternately stacked two by two, rather than one by one. In this case, for example, the thickness of the dielectric layer 17 between the internal electrodes 19 connected to the same external electrode 5 and facing each other may be thinner than the thickness of the dielectric layer 17 between the internal electrodes 19 connected to different external electrodes 5 and facing each other. As can be understood from this, the multiple dielectric layers 17 do not need to have the same shape and size.

[0124] Furthermore, the two types of internal electrodes 19 connected to different external electrodes 5 do not have to face each other. For example, two types of internal electrodes 19 connected to different external electrodes 5 may be provided in the same layer, and an internal electrode 19 facing the two types of internal electrodes 19 may be provided, thereby forming a circuit in which two parallel plate capacitors are connected in series. Also, a circuit in which three or more parallel plate capacitors are connected in series may be formed.

[0125] 9, the internal electrode 19 is sandwiched between the dielectric layers 17 that extend further in the D2 direction (outside) than the two long sides of the internal electrode 19 parallel to the D1 direction, so that the two long sides are not exposed from the -D2 side and +D2 side of the main body 203. However, a configuration in which the long sides are not exposed may be achieved by overlapping another dielectric layer on the -D2 side and +D2 side of the laminate formed of the dielectric layers 17 and the ceramic layers 11. From another perspective, the main body does not need to have a laminated structure in its entirety.

[0126] The electronic component is not limited to a capacitor. For example, the electronic component may be a multilayer electronic component other than a capacitor, or may be a non-multilayer electronic component. Examples of multilayer electronic components include multilayer inductors, multilayer varistors, multilayer ferrite beads, multilayer thermistors, and multilayer filters. Non-multilayer electronic components are diverse, and include, for example, an integrated circuit (IC).

[0127] The multilayer electronic component has, for example, a functional part (7) in which non-conductors (e.g., dielectric layers 17) and conductors (e.g., internal electrodes 19) are alternately laminated. In such a configuration, for example, the cover 9 having one or more ceramic layers 11 and one or more conductor layers 13 can be formed as an extension of the process of forming the functional part. Therefore, even if the configuration of the cover 9 according to the embodiment is adopted, the likelihood of the manufacturing process becoming complicated is reduced.

[0128] The multilayer ceramic filter may have, for example, an LC circuit. As can be seen from this example, the multilayer electronic component may achieve two or more functions (a capacitor and an inductor). The portions achieving different functions may be different portions when viewed from above and / or different portions when viewed from a side.

[0129] The functional portion (7) does not have to be configured symmetrically from top to bottom. Warping may occur due to the asymmetry of the functional portion. The asymmetry of the two covers 9 may contribute to reducing such warping.

[0130] (6. Summary of the embodiment) In the following, the configuration of the electronic component according to the embodiment is extracted, and the effects of the extracted configuration are illustrated. However, the effects illustrated below do not necessarily have to be achieved. In addition, for convenience, symbols of one aspect are used below. However, the matters described below may be applied to an aspect other than the aspect for which the symbol is used, as long as no contradiction or the like occurs.

[0131] A capacitor 1 (an example of an electronic component) according to the embodiment has a functional section 7, a first cover 9A overlapping the functional section 7 on the +D3 side (an example of a first side in a first direction), and a second cover 9B overlapping the functional section 7 on the -D3 side (an example of a second side). The first cover 9A has one or more first ceramic layers 11A and one or more first conductor layers 13A alternately overlapping with the one or more first ceramic layers 11A. The second cover 9B has one or more second ceramic layers 11B and one or more second conductor layers 13B alternately overlapping with the one or more second ceramic layers 11B. The configurations of the first cover 9A and the second cover 9B are asymmetrical with respect to the functional section 7.

[0132] The manufacturing method of the capacitor 1 according to the embodiment includes stacking ceramic green sheets (11) to obtain an unfired laminate (main body portion 3) (first to third rows from the top in FIG. 4), and firing the unfired laminate (main body portion 3) (third row from the top in FIG. 4). The unfired main body portion 3 has a functional portion 7 (e.g., unfired), an unfired first cover 9A overlapping the +D3 side of the functional portion 7, and an unfired second cover 9B overlapping the -D3 side of the functional portion 7. The unfired first cover 9A has one or more layers of first ceramic green sheets (11A) and one or more layers of first conductive paste (13A) alternately overlapping the one or more layers of first ceramic green sheets (11A). The unfired second cover 9B has one or more layers of the second ceramic green sheet (11B) and one or more layers of the second conductive paste (13B) alternately overlapping with the one or more layers of the second ceramic green sheet (11B). The configuration of the unfired first cover 9A and the configuration of the unfired second cover 9B are asymmetric with respect to the functional part 7.

[0133] In this case, for example, as already described, it is possible to reduce the warpage caused by firing. Also, by making the frequencies or phases of the structural or electromagnetic vibrations generated or reflected by the first cover 9A and the second cover 9B different from each other, it is possible to reduce the possibility of unintended resonance occurring in the functional part 7. Furthermore, in cases where the functional part 7 is not asymmetrical in the up-down direction, it is possible to compensate for the asymmetry with respect to the warpage during the manufacturing process or with respect to the strength after manufacturing.

[0134] The first cover 9A and the second cover 9B may differ from each other in at least one of the thicknesses of the corresponding layers (11 and / or 13), the materials of the corresponding layers (11 and / or 13), and the number of conductor layers 13.

[0135] In this case, it is easier to reduce the likelihood that the conductor layer 13 will exert an unintended electromagnetic effect on the functional section 7, as compared to a case where the vertical asymmetry is realized by the dimensions of the conductor layer 13 in the planar direction, as in the uppermost main body section 3A in Fig. 8. Alternatively, it is easier to predict the possibility of unintended electromagnetic effects. Also, it is easier to change the design from the reference design (Comparative Example 1).

[0136] First cover 9A may be thicker than second cover 9B. The total thickness of one or more first conductor layers 13A may be thicker than the total thickness of one or more second conductor layers 13B.

[0137] In this case, for example, as described above, the volume ratio of the conductive paste in the first cover 9A can be relatively increased to reduce warpage. In addition, the first cover 9A is made thicker as the first conductive layer 13A is made thicker, which reduces the need to make the first ceramic layer 11A thin. As a result, insulation is easily ensured. In addition, it is easy to change the design or manufacturing process from the reference design (Comparative Example 1).

[0138] Of the one or more first conductor layers 13A, the thickness of the first conductor layer 13A (first base electrode 21A) located furthest on +D3 may be thicker than the thickness of the second conductor layer 13B (second base electrode 21B) located furthest on the front -D3 side, of the one or more second conductor layers 13B.

[0139] In this case, the vertical asymmetry is realized at the position farthest from the functional section 7, so that the possibility of unintended effects occurring in the functional section 7 due to the asymmetry is reduced. Furthermore, the further away from the neutral plane of warping (deflection) the ceramic green sheet is, the more likely a compressive force in the direction along the layer will act as a warping moment. By thickening the outermost conductor layer 13, such compressive force can be reduced.

[0140] The thickness of the functional portion 7 in the direction D3 may be smaller than both the length in the direction D1 (an example of a second direction) perpendicular to the direction D3 and the length in the direction D2 (an example of a third direction).

[0141] In this case, for example, warping in the direction D3 is likely to occur. Therefore, the configuration of the embodiment that can contribute to reducing warping is effective.

[0142] The capacitor 1 may further include a first external electrode 5a covering the first cover 9A and a second external electrode 5b covering the second cover 9B. Each of the one or more first conductor layers 13A may have a portion exposed to the outside of the first cover 9A and joined to the first external electrode 5a. Each of the one or more second conductor layers 13B may have a portion exposed to the outside of the second cover 9B and joined to the second external electrode 5b. Note that the joined portion may be, for example, a surface of the base electrode 21 opposite to the functional portion 7 and an end portion in a plan view, and may be an end portion in a plan view of the dummy electrode 23.

[0143] In this case, for example, the conductor layer 13, which can contribute to reducing warpage by adjusting its thickness, can contribute to improving the adhesive strength between the external electrodes 5 and the main body 3 and / or contribute to precipitating the external electrodes 5 by electroless plating or electrolytic plating. Therefore, since the conductor layer 13 is not provided just for reducing warpage, the configuration of the capacitor 1 is simplified.

[0144] The first external electrode 5a may be configured to have a portion in direct contact with one or more first ceramic layers 11A and not to include any common material. The second external electrode 5b may be configured to have a portion in direct contact with one or more second ceramic layers 11B and not to include any common material.

[0145] In this case, for example, the external electrode 5 is formed by a method that does not require a base layer covering the entire surface. Furthermore, it is easy to separate the asymmetry of the conductive paste (for example, base electrode 21) for reducing warpage from the configuration of the external electrode 5. As a result, for example, it is easy to fabricate a capacitor 1 that is internally asymmetric but externally symmetrical from top to bottom.

[0146] The average particle diameter of the metal particles 27 constituting the main component of one or more first conductor layers 13A and the average particle diameter of the metal particles 27 constituting the main component of one or more second conductor layers 13B may each be larger than the average particle diameter of the ceramic particles 31 constituting the main component of one or more first ceramic layers 11A and the average particle diameter of the ceramic particles 31 constituting the main component of one or more second ceramic layers 11B.

[0147] In this case, the warpage can be reduced by, for example, the mechanism described with reference to FIG.

[0148] Of the one or more first conductor layers 13A, the thickness t3A of the first conductor layer 13A (first base electrode 21A) located closest to the +D3 side and exposed on the +D3 side from the first cover 9A may be 1.2 to 2.5 times the thickness t3B of the second conductor layer 13B (second base electrode 21B) located closest to the -D3 side and exposed on the -D3 side from the second cover 9B, of the one or more second conductor layers 13B.

[0149] In this case, for example, the thickness t3A is 1.2 times or more as thick as the thickness t3B, so that the above-mentioned effect is easily obtained. Also, the thickness t3A is 2.5 times or less as thick as the thickness t3B, so that the possibility of unintended inconvenience due to asymmetry is reduced.

[0150] The first base electrode 21A may be embedded from the +D3 side into a first ceramic layer 11A located closest to the +D3 side among one or more first ceramic layers 11A. The second base electrode 21B may be embedded from the -D3 side into a second ceramic layer 11B located closest to the -D3 side among one or more second ceramic layers 11B.

[0151] In this case, for example, from another point of view, since the base electrode 21 is disposed replacing a part of the outermost ceramic layer 11, the base electrode 21 occupies a large proportion of the cover 9. As a result, for example, the influence of the vertical asymmetry due to the difference in configuration between the first base electrode 21A and the second base electrode 21B is likely to appear.

[0152] The functional section 7 may have a plurality of internal electrodes 19 and a plurality of dielectric layers 17 alternately stacked in the D3 direction. When seen through in the D3 direction, one or more first conductor layers 13A and one or more second conductor layers 13B may have portions overlapping a region (electrode body 19a) where the multiple internal electrodes 19 overlap each other.

[0153] In this case, for example, it can be said that the conductor layer 13 has a relatively large area. Therefore, for example, the effect of making the conductor layer 13 thicker is improved.

[0154] In the above embodiments, capacitors 1 and 201 are each an example of an electronic component. The D3 direction is an example of the first direction. The +D3 side is an example of the first side. The -D3 side is an example of the second side. The D1 direction is an example of the second direction. The D2 direction is an example of the third direction. The technology according to the present disclosure is not limited to the above embodiments and may be implemented in various aspects. [Explanation of symbols]

[0155] 1...capacitor (electronic component), 7...functional part, 9A...first cover, 9B...second cover, 11A...first ceramic layer, 11B...second ceramic layer, 13A...first conductor layer, 13B...second conductor layer.

Claims

1. A functional part; a first cover overlapping the functional portion on a first side in a first direction; a second cover overlapping a second side of the functional portion opposite to the first side; It has The first cover is one or more first ceramic layers; one or more first conductor layers alternating with the one or more first ceramic layers; The second cover is one or more second ceramic layers; and one or more second conductor layers alternating with the one or more second ceramic layers, The one or more first conductor layers include one or more layers of first electrodes located on a third side in a second direction intersecting the first direction with respect to a center of the first cover in the second direction; one or more layers of second electrodes are located on a fourth side of the first cover opposite to the third side with respect to the center, and are spaced apart from the one or more layers of first electrodes in the second direction, The one or more second conductor layers include one or more layers of third electrodes located on the third side with respect to a center of the second cover in the second direction; one or more fourth electrodes located on the fourth side with respect to the center of the second cover and spaced apart from the one or more third electrodes on the fourth side, a total volume of the one or more first electrodes is greater than a total volume of the one or more third electrodes; The total volume of the one or more second electrodes is greater than the total volume of the one or more fourth electrodes. Electronic components.

2. The first cover and the second cover are different from each other in at least one of the thickness of the corresponding layers, the material of the corresponding layers, and the number of conductor layers. The electronic component according to claim 1 .

3. The first cover is thicker than the second cover, The total thickness of the one or more first conductor layers is greater than the total thickness of the one or more second conductor layers. The electronic component according to claim 1 .

4. Among the one or more first conductor layers, a thickness of a first conductor layer located closest to the first side is greater than a thickness of a second conductor layer located closest to the second side among the one or more second conductor layers. The electronic component according to claim 1 .

5. The thickness of the functional portion in the first direction is smaller than the length in the second direction and the length in a third direction perpendicular to the first direction and the second direction. The electronic component according to claim 1 .

6. a first external electrode covering the first cover; a second external electrode covering the second cover; and each of the one or more first conductor layers has a portion exposed to an outside of the first cover and joined to the first external electrode; Each of the one or more second conductor layers has a portion exposed to the outside of the second cover and joined to the second external electrode. The electronic component according to claim 1 .

7. a first external electrode covering the first cover; a second external electrode covering the second cover; and the first external electrode has a portion that is in direct contact with the one or more first ceramic layers and does not include a common material; The second external electrode has a portion that is in direct contact with the one or more second ceramic layers and does not include a common material. The electronic component according to claim 1 .

8. The average particle size of the metal particles constituting the main component of the one or more first conductive layers and the average particle size of the metal particles constituting the main component of the one or more second conductive layers are each larger than the average particle size of the ceramic particles constituting the main component of the one or more first ceramic layers and the average particle size of the ceramic particles constituting the main component of the one or more second ceramic layers. The electronic component according to claim 1 .

9. Among the one or more first conductor layers, a thickness of a first conductor layer located closest to the first side and exposed from the first cover to the first side is 1.2 to 2.5 times a thickness of a second conductor layer located closest to the second side and exposed from the second cover to the second side among the one or more second conductor layers. The electronic component according to claim 1 .

10. a first conductor layer located closest to the first side and exposed from the first cover to the first side among the one or more first conductor layers is embedded from the first side into a first ceramic layer located closest to the first side among the one or more first ceramic layers, Among the one or more second conductor layers, a second conductor layer located closest to the second side and exposed to the second side from the second cover is embedded from the second side into a second ceramic layer located closest to the second side among the one or more second ceramic layers. The electronic component according to claim 1 .

11. the functional portion has a plurality of internal electrodes and a plurality of dielectric layers alternately stacked in the first direction, When viewed in the first direction, the one or more first conductor layers and the one or more second conductor layers have portions that overlap with regions where the plurality of internal electrodes overlap each other. The electronic component according to claim 1 .

12. A total thickness of the one or more first electrodes is thicker than a total thickness of the one or more third electrodes; The total thickness of the one or more second electrodes is greater than the total thickness of the one or more fourth electrodes. The electronic component according to claim 1 .

13. In at least one of the one or more first conductor layers, the length of the first electrode in the second direction is longer than the length of each of the one or more third electrodes in the second direction, and the length of the second electrode in the second direction is longer than the length of each of the one or more fourth electrodes in the second direction. The electronic component according to claim 1 .

14. The functional portion has a plurality of internal electrodes and a plurality of dielectric layers alternately stacked in the first direction, a thickness of each of the one or more first electrodes is greater than a thickness of each of the plurality of internal electrodes; a thickness of each of the one or more second electrodes is greater than a thickness of each of the plurality of internal electrodes; a thickness of each of the one or more third electrodes is greater than a thickness of each of the plurality of internal electrodes; The thickness of each of the one or more fourth electrodes is greater than the thickness of each of the plurality of internal electrodes. The electronic component according to claim 1 .

15. The first cover is thicker than the second cover. The electronic component according to claim 1 .

16. stacking the ceramic green sheets to obtain a laminate in an unfired state; and Firing the unfired laminate; Including, The unfired laminate is An unfired functional part; a first cover in an unfired state overlapping a first side of the unfired functional portion; a second cover in an unfired state overlapping a second side of the unfired functional portion opposite to the first side, The first cover in the unfired state is One or more layers of a first ceramic green sheet; and one or more layers of a first conductive paste alternately overlapping the one or more layers of the first ceramic green sheets, The unfired second cover is one or more layers of second ceramic green sheets; and one or more layers of a second conductive paste alternately overlapping the one or more layers of the second ceramic green sheets, The one or more layers of the first conductive paste include one or more layers of a first electrode paste located on a third side in a second direction intersecting the first direction with respect to a center of the first cover in the second direction; one or more layers of second electrode paste are located on a fourth side opposite to the third side with respect to the center of the first cover and are spaced apart from the one or more layers of first electrode paste in the second direction, The one or more layers of the second conductive paste include one or more layers of a third electrode paste located on the third side with respect to a center of the second cover in the second direction; one or more layers of fourth electrode paste located on the fourth side with respect to the center of the second cover and spaced apart from the one or more layers of third electrode paste in the second direction, a total volume of the pastes for the one or more first electrodes is greater than a total volume of the pastes for the one or more third electrodes, The total volume of the pastes for the one or more second electrodes is greater than the total volume of the pastes for the one or more fourth electrodes. A method for manufacturing electronic components.

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