Electronic component and production method for electronic component

Abstract

This electronic component comprises: a functional part; a first cover that overlaps the functional part on a first side in a first direction; and a second cover that overlaps the functional part on a second side that is the opposite side from the first side. The first cover has: one or more first ceramic layers; and one or more first conductor layers alternately stacked with respect to 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 stacked with respect to the one or more second ceramic layers The structure of the first cover and the structure of the second cover are asymmetrical to each other with respect to the functional part.

Description

Electronic Component and Method for Manufacturing the Same

[0001] The present disclosure relates to an electronic component such as a multilayer ceramic capacitor and a method for manufacturing the same.

[0002] A multilayer ceramic capacitor in which ceramic layers and internal electrodes are alternately laminated is known (for example, Patent Document 1 below). Patent Document 1 discloses a configuration in which an underlayer is provided on the upper surface of a functional portion composed of a ceramic layer and an internal electrode. Patent Document 1 discloses a problem that the capacitor warps due to the sintering shrinkage rates of the ceramic component and the metal component. In Patent Document 1, in order to solve the above problem, the underlayer is formed of ceramics containing metal particles.

[0003] International Publication No. 2012 / 043740

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

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

[0006] A perspective view showing a capacitor according to an embodiment. A schematic exploded perspective view of the capacitor in Figure 1. A cross-sectional view along line III-III in Figure 1. A schematic diagram illustrating a method for manufacturing a capacitor. A schematic diagram illustrating an example of the operation of the embodiment. A diagram showing the warping of capacitors according to comparative examples and embodiments. A diagram showing the warping of capacitors according to other comparative examples and embodiments. A cross-sectional view showing another example regarding the asymmetry of the capacitor in the vertical direction. A cross-sectional view showing another example regarding the arrangement of terminals.

[0007] The embodiments relating to this disclosure will be described below with reference to the drawings. The figures used in the following description are schematic. Therefore, for example, the dimensional ratios on the drawings do not necessarily match those of reality. Also, the dimensional ratios may not match between drawings. Certain shapes and / or dimensions may be exaggerated, or details may be omitted. However, the above does not negate the fact that the actual shape and / or dimensions may be as shown in the drawings, or that the characteristics of the shape and / or dimensions may be extracted from the drawings.

[0008] Regarding aspects described relatively later, only the differences from aspects described relatively earlier will be mentioned. Unless otherwise specified, matters may be treated the same as those described earlier, or inferred from those aspects. For convenience, the same symbols may be used for corresponding components 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 is acceptable as long as it does not create inconsistencies. When referring to a rectangle (or rectangular shape) or a rectangular parallelepiped (or rectangular shape), the corners may be chamfered. Also, relatively small recesses or protrusions (intentional, not errors) may be formed. The same applies to other shapes. When referring to a predetermined layer having a certain thickness, variations in thickness due to manufacturing tolerances are acceptable (as long as a certain thickness is intended).

[0010] The determination of whether various dimensions fall within the ranges exemplified in the description of the embodiments (absolute values ​​such as μm or relative values ​​to other dimensions) may be made in a reasonable manner. For example, the dimensions of singular parts may be disregarded. More specifically, for example, when determining whether a thickness falls within a predetermined range, chamfered portions may be ignored. Also, for example, in a layer intended to have a certain thickness, if the thickness of the edges differs significantly from the thickness of the rest of the layer (e.g., significantly thinner) compared to the majority of the layer (e.g., 60% or more or 80% or more of the area), the thickness of the edges may be disregarded. Furthermore, if there is variation in thickness in the majority of the predetermined layer intended to have a certain thickness, for example, the average value may be referred to. Of course, if both the minimum and maximum values ​​of the thickness fall within the numerical range, there is no need to specifically identify and refer to the average value.

[0011] With respect to the material (conductive material or insulating material, etc.), the main component may be, for example, a component accounting for 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 terms "component of 60 wt% or more," "component of 80 wt% or more," or "component of 100 wt%," as long as it does not cause any inconsistencies.

[0012] As the manufacturing process of electronic components progresses, the material composition and microstructure of various parts of the electronic components may change. For convenience, the same reference numerals and terminology may be used before and after such changes.

[0013] (Outline of Embodiments) Figure 1 is a perspective view showing a capacitor 1 (an example of an electronic component) according to an embodiment. For convenience, Figure 1 and other figures described later are shown with a Cartesian coordinate system D1, D2, and D3. The capacitor 1 may be used with either the top or bottom facing upwards. However, for convenience in describing the embodiments, the +D3 side may be considered upwards, and terms such as top surface and bottom surface may be used.

[0014] Capacitor 1 is, for example, a multilayer ceramic capacitor. 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 (viewed in the D3 direction). The external electrodes 5 contribute to the electrical connection between capacitor 1 and other electronic components (for example, a circuit board not shown).

[0015] Figure 3 is a cross-sectional view taken along the line III-III in Figure 1. Note that Figure 3 shows the D1D3 cross-section where the external electrode 5 on the +D2 side is cut. However, the D1D3 cross-section where the external electrode 5 on the -D2 side is cut, the D2D3 cross-section where the external electrode 5 on the -D1 side is cut, and the D2D3 cross-section where the external electrode 5 on the +D1 side is cut are basically the same as in Figure 3. In describing the embodiments, for convenience, the terms D1, D2, and D3 may be used to describe the positional relationships between components, etc., assuming the cross-section illustrated in Figure 3, without further explanation.

[0016] In Figure 3, for convenience, the boundary lines between the ceramic layer 11 and the dielectric layer 17, which will be described later, are shown. However, these boundary lines do not need to be observable. The ceramic layer 11 and the dielectric layer 17 may be identified as different layers based on the fact that they are separated by the conductor layer 13 and the internal electrode 19, which will be described later.

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

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

[0019] Each cover 9 has one or more (three layers in the illustrated example) ceramic layers 11 and one or more conductive layers 13 (three layers in the illustrated example) that are stacked alternately. For convenience, the term "alternating" is used, but it is also acceptable to have only one ceramic layer 11 and one conductive layer 13. The ceramic layer 11 contributes, for example, to the insulation of the functional part 7. The conductive layer 13 contributes, for example, to the deposition of metal that will become the external electrode 5 by a plating method, and / or to the adhesion force of the external electrode 5 to the main body 3.

[0020] Furthermore, the configuration of the first cover 9A and the configuration of the second cover 9B are asymmetrical with respect to the functional part 7 (they are asymmetrical vertically). For example, in the illustrated example, the thickness t1A of the first cover 9A is greater than the thickness t1B of the second cover 9B. Also, the thickness t3A of the first conductor layer 13A located on the +D3 side is greater than the thickness t3B of the second conductor layer 13B located on the -D3 side. This vertically asymmetrical configuration reduces warping that occurs when the laminate that forms the main body 3 is fired during the manufacturing process of the capacitor 1, for example, as will be described in detail later.

[0021] It should be noted that the effects described above do not necessarily have to be achieved. Furthermore, technical ideas different from those described above may be extracted from this disclosure. In this case, for example, a configuration different from the above description may be adopted. For example, the cover 9 does not have to include the conductor layer 13.

[0022] The above is an overview of the embodiment. Below, the embodiment will be described in general order. 1. Capacitor configuration (Figures 1 to 3) 1.1. Overall configuration 1.2. Functional part 1.3. Cover 1.3.1. Entire cover 1.3.2. Ceramic layer 1.3.3. Conductor layer (dummy electrode and base electrode) 1.3.4. Embedding 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. Examples (Figures 6 and 7) 5. Other embodiments (Figures 8 and 9) 5.1. Other examples related to vertical asymmetry 5.2. Other examples related to terminals 5.3. Other examples of electronic components other than capacitors 6. Summary of the embodiment

[0023] (1. Capacitor Configuration) (1.1. Overall Configuration) The capacitor 1 shown in Figure 1 is configured as, for example, a surface-mounted chip component. Specifically, for example, the capacitor 1 is placed with its -D3 side or +D3 side facing a circuit board (not shown). The capacitor is then mounted on the circuit board by joining the four pads of the circuit board and the four external electrodes 5 with a conductive bonding material (for example, solder) (not shown).

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

[0025] The shape of the main body 3 is, for example, generally a thin rectangular parallelepiped. Thinness means, for example, that the length in the D3 direction of the main body 3 is shorter than the lengths in the D1 direction and the D2 direction (or, for example, the maximum length if it is not a rectangular parallelepiped). The rectangular parallelepiped may be a square (as shown in the illustration) or a rectangle (excluding squares; the same applies hereinafter) in plan view. Although not specifically shown, the corners of the main body 3 may be relatively chamfered in plan view and / or side view. The specific dimensions of the main body 3 (or capacitor 1) are arbitrary. The specific dimensions of the main body 3 will be given as examples later in the explanation of the specific dimensions of the cover 9.

[0026] As previously stated, the first cover 9A and the second cover 9B are asymmetrical in the vertical direction. However, unless otherwise specified, multiple components of the same type (e.g., 5, 11, 13, 17, and 19, etc.) may be provided with basically the same (or corresponding) shape, size, material, and position. Therefore, unless otherwise specified, and unless contradictions arise, the description of one component may be considered to apply to other components of the same type.

[0027] A single layered (film-like) component (e.g., 5, 11, 13, 17, and 19, etc.) may be composed entirely of one material. However, a single layered component may be composed of layers made of different materials stacked on top of each other. Furthermore, a single layered component composed entirely of one material may, when considering the manufacturing process, be composed of a single layer, or it may be composed of multiple layers made of the same material stacked on top of each other.

[0028] (1.2. Functional Section) The shape of the functional section 7 shown in Figure 3 is, for example, generally a thin rectangular parallelepiped. Its planar shape is basically the same as that of the main body section 3. The thickness of the functional section 7 is arbitrary. Later, in the explanation of the specific dimensions of the cover 9, the specific thickness of the functional section 7 will also be given as an example. The functional section 7 has a generally symmetrical configuration in the vertical direction. This generally symmetrical configuration includes a configuration in which the uppermost internal electrode 19 (described later) and the lowermost internal electrode 19 have asymmetry.

[0029] The functional section 7 has multiple dielectric layers 17 and multiple internal electrodes 19 that are alternately stacked. This enables it to function as a capacitor.

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

[0031] The internal electrode 19 is layered and has a certain thickness. The thickness of the internal electrode 19 is arbitrary; for example, it may be thinner than, the same as, or thicker than the thickness of the region between the internal electrodes 19 in 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, or it may be 3.0 μm or less, 2.0 μm or less, or 1.0 μm or less. The above lower and upper limits may be combined in any way. The material of the internal electrode 19 (for example, the main component) is, for example, a metal. The specific type of metal is arbitrary; for example, all or the main component of the metal is a base metal. A base metal is, for example, Ni or Cu or an alloy containing at least one of these as the main component. The material of the internal electrode 19 may also include ceramics (common material).

[0032] Figure 2 is an exploded perspective view of capacitor 1. Figure 2 is schematic for understanding the planar shape and relative position of internal electrodes 19, etc. Therefore, in Figure 2, various layers are shown in fewer numbers compared to Figure 3.

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

[0034] The electrode body 19a is a region where adjacent internal electrodes 19 overlap each other in the D3 direction. The electrode body 19a is located inside the outer edge of the dielectric layer 17 and is not exposed from the side of the functional part 7.

[0035] A pair of lead electrodes 19b extend to 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. In the D3 direction, adjacent internal electrodes 19 are connected to different pairs of external electrodes 5.

[0036] (1.3. Cover) (1.3.1. Overall Cover) The cover 9 shown in Figure 3 is, for example, layered in shape and dimensions that overlap the functional part 7 without excess or deficiency. The thickness of the cover 9 is generally constant.

[0037] As previously described, in the illustrated example, the two covers 9 differ in the thickness of the cover 9 and the thickness of the outermost conductor layer 13. In addition, in the illustrated example, in addition to the above differences, the thickness of the non-placed region (towards the center in the D1 direction) of the conductor layer 13 within the outermost ceramic layer 11 also differs between the two covers 9. Aside from these differences, the configurations of the two covers 9 may be identical.

[0038] (1.3.2. Ceramic Layer) The ceramic layer 11 is layered and has a generally constant thickness, except for variations in thickness due to overlap with the conductive 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 perspective, the number of conductive layers 13) is arbitrary. In the illustrated example, three layers are shown, 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 conductors) may be thicker than the thickness of the dielectric layer 17 (between the internal electrodes 19) (as shown in the illustration), the same as, or thinner than. Also, for example, the thicknesses of multiple ceramic layers 11 may be the same as 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 or may not be a material generally classified as a dielectric. In the former case, the material of the ceramic layer 11 may or may not be the same as the material of the dielectric layer 17. The materials of multiple ceramic layers 11 may or may not be the same as each other. Examples of ceramics (all or the main component thereof) and dielectrics include, for example, barium titanate (BaTiO2). ３ ), titanium dioxide (TiO ２ ), strontium titanate (SrTiO ３ ), calcium titanate (CaTiO ３ ) and calcium zirconate (CaZrO３ ) can be mentioned.

[0042] (1.3.3 Conductor Layer (Dummy Electrode and Underlying Electrode)) As shown in FIGS. 2 and 3, each conductor layer 13 has electrodes (21 or 23) located at the four corners in the plan view of the capacitor 1. Here, the electrodes of the outermost conductor layer 13 shall be referred to as underlying electrodes 21 (21A and 21B). The electrodes of the other conductor layers 13 shall be referred to as dummy electrodes 23 (23A and 23B).

[0043] The dummy electrode 23 and the underlying electrode 21 may have the same configuration as each other except for the points where their positions in the D3 direction are different. Therefore, in the description of this section, for the sake of convenience, the description of the dummy electrode 23 may be given, and the description of the underlying electrode 21 may be omitted. Unless otherwise specified and as long as there is no contradiction, the term of the dummy electrode 23 may be replaced with the term of the underlying electrode 21.

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

[0045] In the plan view, the position, shape, and dimensions of the dummy electrode 23 are arbitrary. In the illustrated example, the position, shape, and dimensions of the dummy electrode 23 are, in the plane perspective, schematically the same as those of the external electrode 5 without excess or deficiency (however, the external electrode 5 is slightly wider). Also, the dummy electrode 23 has a rectangular shape (a square in the illustrated example) with four sides parallel to the four sides of the rectangular ceramic layer 11 (a square in the illustrated example).

[0046] Furthermore, as can be seen from Figures 2 and 3, in planar projection, the dummy electrode 23 partially overlaps with the region (electrode body 19a) where multiple internal electrodes 19 (internal electrodes 19 connected to different external electrodes 5) overlap each other. This region can be said to be a region for securing capacitance. The overlapping area between this region and the dummy electrode 23 is arbitrary.

[0047] The thickness of the dummy electrode 23 may be thicker than, for example, the thickness of the internal electrode 19 (as shown in the illustration), the same as, or thinner than, the thickness of the internal electrode 19. The thickness of the dummy electrode 23 may also be thinner than, the same as, or thicker than, the thickness of the ceramic layer 11 (for example, the thickness between electrodes). The thicknesses of one or more dummy electrodes 23 and the base electrode 21 may be the same or different. In the illustrated example, the thicknesses of multiple dummy electrodes 23 are the same. Furthermore, the thickness of the base electrode 21 (t3A and t3B, respectively) is thicker than the thickness of the dummy electrode 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 explanation of the material of the internal electrode 19 may be applied to the material of the dummy electrode 23.

[0049] (1.3.4. Embedding structure of the base electrode) In the example shown in Figure 3, the first base electrode 21A is embedded from above in 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 non-placed area of ​​the first base electrode 21A; the same applies hereafter in this section).

[0050] When referring to a flush surface, 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. The position of the upper surface may be reasonably determined as described above, for example, by the average value excluding special parts such as the edges, or by the distance from a reference surface (planar or curved) that takes warping into consideration (the same applies to the position of the lower surface described below).

[0051] When considering the case in which the upper surface of the first base electrode 21A and the upper surface of the outermost first ceramic layer 11A are not flush, the amount of embedding of the former relative to the latter is arbitrary. The amount of embedding 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 amount of embedding may be less than 50% of the thickness of the base electrode 21, or it may be 50% or more, or it may be 80% or more.

[0052] The method for embedding the first base electrode 21A into the outermost first ceramic layer 11A is arbitrary. For example, the outermost first ceramic layer 11A may be formed from two layers of ceramic green sheets. A conductive paste, which will become the first base electrode 21A, is placed on the upper surface of the lower ceramic green sheet, and a hole (notch) is made in the upper ceramic green sheet in the region where the first base electrode 21A will be located. Alternatively, in addition to or instead of this method, the first base electrode 21A may be embedded into 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 was used as an example, the second base electrode 21B is similar. The above explanation may be applied to the second base electrode 21B by substituting 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 previously described, the configuration of the first cover 9A and the second cover 9B are asymmetrical with respect to the functional part 7. Note that the asymmetry referred to here does not include asymmetry due to unintended manufacturing errors. For example, even if the capacitor 1 warps unintendedly during firing, causing the first cover 9A and the second cover 9B to be asymmetrical in the vertical direction, this does not constitute asymmetry as defined here.

[0055] In the example shown in Figure 3, as previously described, the thickness t1A of the first cover 9A is greater than the thickness t1B of the second cover 9B, and the thickness t3A of the first base electrode 21A is greater than the thickness t3B of the second base electrode 21B. In this case, the specific values ​​of thicknesses t1A, t1B, t3A, and t3B are arbitrary. Examples of specific values ​​for these thicknesses, as well as values ​​for various other dimensions, are given below.

[0056] The dimensional ranges shown below are merely examples, and values ​​outside these ranges may be used. Furthermore, examples of different dimensional values ​​may be combined in any way. For example, the thickness of the main body 3 and the thickness of the cover 9 may be combined in any way. The specific values ​​exemplified below may be used in other embodiments described later (for example, embodiments where t1A = t1B and / or t3A = t3B), provided that no inconsistencies arise. The specific values ​​exemplified below may also take into account embodiments different from the illustrated examples (for example, embodiments where the dummy electrode 23 is not provided).

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

[0058] The thickness of the functional part 7 may be 30% or more, 40% or more, 50% or more, 60% or more, or 70% or more relative to the thickness of the main body part 3, and may also be 90% or less, 80% or less, or 70% or less. The above lower and upper limits may be combined in any way so as not to cause any contradiction.

[0059] The boundary between the functional part 7 and the cover 9 may be determined reasonably. For example, if the material of the dielectric layer 17 and the material of the ceramic layer 11 are the same, the +D3 side surface of the internal electrode 19 located furthest towards +D3 and the -D3 side surface of the internal electrode 19 located furthest towards -D3 may be identified as the upper and lower surfaces of the functional part 7.

[0060] The thickness of each cover 9 (t1A or t1B) may be 5% or more, 10% or more, or 15% or more relative to the thickness of the main body 3, and may also be 35% or less, 30% or less, 25% or less, 20% or less, or 15% or less. The above lower and upper limits may be combined in any way so as not to cause any contradiction. Furthermore, the thickness of each cover 9 (t1A or t1B) may be 5 μm or more, 10 μm or more, or 15 μm or more, and may also 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 and upper limits may be combined in any way so as not to cause any contradiction.

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

[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 also be 90% or less, 60% or less, 50% or less, or 40% or less. The above lower and upper limits may be combined in any way so as not to cause any contradiction. Furthermore, 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 also be 20.0 μm or less, 10.0 μm or less, or 5.0 μm or less. The above lower and upper limits may be combined in any way so as not to cause any contradiction.

[0063] The difference in thickness of the base electrode 21 (t3A - t3B) may be the same as the difference in thickness of the cover 9 (t1A - t1B) described above. Also, the difference in thickness of the base electrode 21 (t3A - t3B) 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, relative to the thickness t3B of the second base electrode 21B. The above lower and upper limits may be combined in any way so as not to cause any contradiction. The ratio of the thickness of the first base electrode 21A to the thickness of the second base electrode 21B (t3A / t3B) 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 and upper limits may be combined in any way.

[0064] As examples of thickness ranges close to the thickness of the cover 9 and base electrode 21 in the embodiments described later, the following ranges can also be given as examples: • Thickness t1A of the first cover 9A: 10 μm or more and 16 μm or less • Thickness t1B of the 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, provided that 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 of the length of the main body 3 in the D1 direction, or 45% or less, 40% or less, or 30% or less. The above lower and upper limits may be combined in any way 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 and upper limits may be combined in any way. Although examples of lengths in the D1 direction have been given, these lengths may also be applied to the lengths in the D2 direction. Also, the examples of dimensions for the base electrode 21 in this paragraph may also 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 also be 50% or less, 30% or less, or 20% or less. The above lower and upper limits may be combined in any way so as not to cause any contradiction. Also, 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 also 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 and upper limits may be combined in any way so as not to cause any contradiction.

[0067] The thickness of each ceramic layer 11 (for example, 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 also be 50% or less, 30% or less, or 20% or less. The above lower and upper limits may be combined in any way so as not to cause any contradiction. Furthermore, the thickness of each ceramic layer 11 (for example, between electrodes) may be 1.0 μm or more, or 2.0 μm or more, and may also be 10.0 μm or less, or 5.0 μm or less. The above lower and upper limits may be combined in any way.

[0068] (1.4. External Electrodes) The external electrodes 5 are, for example, layered in a manner that is basically constant in thickness. As shown in Figure 1, the external electrodes 5 cover four surfaces (top, bottom, and two sides) of the main body 3, for example, at the corners in a plan view of the main body 3. This allows one external electrode 5 to be connected to one lead electrode 19b on two sides of the main body 3, and also allows surface mounting on either the top or bottom surface of the capacitor 1. Furthermore, as previously described, the external electrodes 5 are fixed to the exposed portion of the conductor layer 13 from the cover 9. In addition, the external electrodes 5 are also fixed to the ceramic layer 11 and the dielectric layer 17. The shape and dimensions of the portions on each surface of the external electrodes 5 are arbitrary.

[0069] The thickness of the external electrode 5 is arbitrary. For example, the thickness of the external electrode 5 may be greater 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 the thickness of the base electrode 21 (t3A or t3B), or it may be 10 times or less, 5 times or less, or 3 times or less. The above lower and upper limits may be combined in any way. 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 it may be 30 μm or less, 20 μm or less, or 10 μm or less. The above lower and upper limits may be combined in any way so as not to cause any contradictions.

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

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

[0072] (2. Method for Manufacturing Capacitors) The method for manufacturing capacitor 1 can be varied. For example, the method for manufacturing capacitor 1 may be the same as known methods, except for the setting of specific dimensions. An example of a manufacturing method is shown below.

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

[0074] First, a ceramic green sheet is prepared to form the dielectric layer 17 and the ceramic layer 11. Next, a conductive paste is applied (for example, printed) to the ceramic green sheet to form the internal electrode 19, dummy electrode 23, or base electrode 21.

[0075] Next, as shown in the first to third rows from the top of Figure 4, ceramic green sheets are stacked to create a laminate that will become the main body 3 (3Z) (the unfired main body 3). The stacking order at this time is arbitrary. In the illustrated example, the ceramic green sheets are stacked one by one in order from the bottom (second cover 9B side). Contrary to the illustrated example, for example, the ceramic green sheets may be stacked one by one in order from the top (first cover 9A side), and / or several stacked sheets may be stacked on top of each other.

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

[0077] The process up to the point of fabricating the laminate described above is carried out using a base substrate that is large enough to produce a large number of main body parts 3. After fabricating the laminate, the base substrate containing the laminate is divided into pieces (for example, cut) that roughly correspond to the size of the main body parts 3.

[0078] Next, as shown in the third row from the top of Figure 4, the laminate having the size of the main body 3 is fired. The firing method is arbitrary. In the illustrated example, an electric furnace 25 is schematically shown. In addition, firing may be performed by irradiating the laminate with microwaves, for example.

[0079] Degreasing may be performed before firing. Firing may be carried out, for example, in a reducing atmosphere. Re-oxidation heat treatment may be performed after firing. Polishing (e.g., barrel polishing) of the main body 3 may be performed before and / or after firing. During polishing, for example, the edges of the main body 3 may be chamfered, or the sides of the main body 3 may be polished.

[0080] After firing of 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 (top or bottom 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 electroplating. Alternatively, thin film formation methods such as the dip method, printing method, CVD (Chemical Vapor Deposition), or PVD (Physical Vapor Deposition) may be employed. As can be understood from the above, the base electrode 21, dummy electrode 23, and internal electrode 19 may or may not contribute to the deposition of metal.

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

[0082] Factors that can cause warping include the following: During the process of laminating ceramic green sheets, a relatively low-pressure press is applied each time a ceramic green sheet is stacked. This press contributes, for example, to the bonding of the ceramic green sheets together. The lower ceramic green sheets are pressed more often, resulting in a higher density of ceramic particles. Conversely, the upper ceramic green sheets have a lower density of ceramic particles. As a result, during sintering, the degree of shrinkage is greater at the top. Consequently, the compressive stress along the layers becomes greater at the top, causing warping with a concave shape at the top.

[0083] As previously stated, in this disclosure, when determining whether 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 excluded. Differences in the density of ceramic particles due to the lamination order and pressing are manufacturing errors. Therefore, even if the microstructure of the first cover 9A and the second cover 9B differs after firing due to differences in density before firing (even if such prior art exists), it will be determined that there is no asymmetry as referred to herein.

[0084] (3. Examples of effects due to asymmetry and examples of particle size) As shown in the bottom row of Figure 4, the main body 3 according to the embodiment exhibits reduced warping due to firing compared to the main body 3Z according to the comparative example. The reason for this is, for example, as follows.

[0085] Figure 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 Figure 5, the upper section shows the metal particles 27 contained in the conductive paste (underlay electrode 21) and the organic material layer 29 consisting of a binder, etc. The lower section shows the ceramic particles 31 contained in the ceramic green sheet (ceramic layer 11) and the organic material layer 33 consisting of a binder, etc. Also in Figure 5, the left side shows the state before firing, and the right side shows the state after firing.

[0087] Generally, the particle size of the metal particles 27 is larger than that of the ceramic particles 31. Also, the organic material layer 29 and the organic material layer 33 are often made of the same or similar material. Furthermore, even if the particle sizes of the metal particles 27 and the ceramic particles 31 are different, the thickness t7 of the organic material layers 29 and 33 is generally the same.

[0088] Therefore, in conductive paste, the surface area of ​​the particles relative to the volume of the particles is smaller compared to ceramic green sheets, and consequently, the volume of organic matter relative to the volume of the particles is smaller. Furthermore, when organic matter disappears during firing, the volume ratio of organic matter loss is smaller in conductive paste than in ceramic green sheets. As a result, the degree of shrinkage of conductive paste is smaller than that of ceramic green sheets.

[0089] On the other hand, as shown in Figure 3, because the first base electrode 21A is thicker than the second base electrode 21B, the volume ratio of conductive paste in the first cover 9A before firing is greater than the volume ratio of conductive paste in the second cover 9B before firing. Consequently, the amount of shrinkage in the layer-oriented direction of the first cover 9A is smaller than the amount of shrinkage in the layer-oriented direction of the second cover 9B. As a result, the upward concave warp in the main body 3 is reduced.

[0090] Intuitively, if the first cover 9A is made thicker than the second cover 9B, 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 part 7 would increase in proportion to the increase in thickness, thus promoting warping with a concave upper surface. However, in reality, as explained by the estimated mechanism described above, and as shown in the embodiments described later, the warping is reduced. Thus, the capacitor 1 according to this embodiment produces an effect that contradicts intuitive expectations, and is groundbreaking.

[0091] Although not shown in Figure 5, the metal particles 27 and ceramic particles 31 grow during firing. However, since the difference in diameter between the two is relatively large, the relative sizes before firing are usually maintained after firing. Therefore, it is possible to determine whether or not the above effect occurred from the size of the particles after firing.

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

[0093] Furthermore, for example, the average particle diameter of the metal particles (after firing) of the base electrode 21 and 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 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 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 dielectric layer 17.

[0094] Furthermore, the ratio of organic matter to metal particles or ceramic particles before firing is also arbitrary. For example, in the conductive paste that will become the base electrode 21, dummy electrode 23, and internal electrode 19, when the mass of metal particles is set to 100, 10 to 40 parts by mass of organic matter may be mixed in. Also, in the ceramic green sheet that will become the ceramic layer 11 and dielectric layer 17, when the mass of ceramic particles is set to 100, 10 to 40 parts by mass of organic matter may be mixed in.

[0095] (4. Examples) The main body of the capacitor according to the comparative example and the example was fabricated, and its warp was measured. As a result, it was confirmed that the example had reduced warp compared to the comparative example. Specifically, it is as follows.

[0096] Comparative examples and embodiments with different configurations regarding vertical symmetry were established as follows: Comparative Example 1: A capacitor with vertical symmetry. Comparative Example 2: A capacitor in which the second cover 9B and the second base electrode 21B are thickened compared to Comparative Example 1. Embodiment: A capacitor in which the first cover 9A and the first base electrode 21A are thickened compared to Comparative Example 1. Unless otherwise specified, the comparative examples and embodiments are the same as capacitor 1 in the embodiment.

[0097] Comparative Examples 1, 2, and 3 are set up for the main body portions of capacitors with different standard sizes. For convenience, Comparative Examples 1, 2, and 3 may be referred to as "A" or "B" as follows: • Comparative Example 1A, Comparative Example 2A, and 3333: Size A • Comparative Example 1B, Comparative Example 2B, and 3333: Size B

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

[0099] The thicknesses of the cover 9 and base electrode 21 in 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 example: 10 μm - Thickness of the second cover 9B in Comparative Example 2 and thickness of 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 example: 3 μm - Thickness of the second base electrode 21B in Comparative Example 2 and thickness of the first base electrode 21A in the example: 5 μm Note that the above thicknesses of the cover 9 and base electrode 21 are common to sizes A and B, and are design values ​​after firing.

[0100] The average particle sizes of the metal and ceramic particles before and after firing fall within the ranges exemplified earlier (or the narrower range if more than one range is shown). Furthermore, the material of the metal particles contained in the conductive paste (13 and 19) was Ni. The material of the ceramic particles contained in the ceramic green sheets (11 and 17) was BaTiO ３ It was determined that...

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

[0102] Figures 6 and 7 show the evaluation results described above. In these figures, the horizontal axis represents the WP / T × 100 (%) ratio described above. The vertical axis represents the number of samples. Figure 6 corresponds to the comparative example and example of size A. Figure 7 corresponds to the comparative example and example of size B. In each figure, the top row corresponds to comparative example 1, the middle row corresponds to comparative example 2, and the bottom row corresponds to the example.

[0103] As shown in these figures, Comparative Example 2 is more likely to exhibit greater warping than Comparative Example 1. On the other hand, the Example is more likely to exhibit less warping than Comparative Example 1.

[0104] More specifically, focusing on size A (Figure 6), in Comparative Example 1A, there were no samples with a warp of 9% or less, whereas in Example A, all samples had a warp of 9% or less. Also, focusing on size B (Figure 7), in Comparative Example 1B, only one sample had a warp of 9% or less, whereas in Example B, all samples had a warp of 9% or less.

[0105] (5. Other Embodiments) (5.1. Other Examples Related to Upper and Lower Asymmetry) Figure 8 is a cross-sectional view showing another example related to the asymmetry of the two covers 9. Note that the examples of asymmetry described above (asymmetry in the thickness of the cover 9 and / or the base electrode 21) and the following other examples may be combined in any way.

[0106] In the main body 3A shown in the uppermost part of Figure 8, the length L1A of the first conductor layer 13A is longer than the length L1B of the second conductor layer 13B in a predetermined cross-section. As a result, for example, the volume ratio of conductive paste in the first cover 9A before firing increases. Consequently, warping with an upward concave shape is reduced by a mechanism similar to that when the first base electrode 21A is thickened.

[0107] As shown in this example, vertical asymmetry may be achieved by differences in the configuration of the first conductor layer 13A and the second conductor layer 13B in the left-right direction. The specific difference and ratio of lengths L1A and L1B are arbitrary. The objects whose configurations differ from each other in the left-right direction are arbitrary and may be, for example, the base electrode 21 and / or some or all of the dummy electrode 23.

[0108] In the main body 3B shown in the second row from the top of Figure 8, the thickness t9A of the first dummy electrode 23A is greater than the thickness t9B of the second dummy electrode 23B. This reduces warping with an upward concave shape through a mechanism similar to that of the first base electrode 21A, for example.

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

[0110] In the main body 3C shown in the third row from the top of Figure 8, the number of layers of the first conductor layer 13A (first dummy electrode 23A) is greater than the number of layers of the second conductor layer 13B (second dummy electrode 23B). As a result, for example, the volume ratio of conductive paste in the first cover 9A before firing is increased, and warping with an upward concave shape is reduced by a mechanism similar to that when the first base electrode 21A is made thicker.

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

[0112] In the main body 3D shown at the bottom of Figure 8, the average particle size of the ceramic particles 31A of the ceramic green sheet that forms the first cover 9A is larger than the average particle size of the ceramic particles 31B of the ceramic green sheet that forms the second cover 9B. As can be understood from the explanation of Figure 5, in this case the degree of shrinkage of the first cover 9A is smaller compared to when ceramic particles 31B are used instead of ceramic particles 31A. As a result, the warping with an upward concave shape is reduced.

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

[0114] Although not specifically shown in the diagram, the solid content ratio in the ceramic green sheet and / or conductive paste may be made larger for the first cover 9A than for the second cover 9B to reduce warping that causes a concave top. Alternatively, the proportion of co-material (ceramic particles) contained in the conductive paste may be made smaller for the first cover 9A than for the second cover 9B to reduce warping that causes a concave top.

[0115] As can be seen from the examples in Figure 3 and the first to third rows from the top in Figure 8, vertical asymmetry may be achieved by making the volume ratio of the conductive layer 13 (unfired conductive paste) in the first cover 9A larger 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 in Figure 8, vertical asymmetry may be achieved by making the total thickness of the conductive 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 in Figures 3 and 8 from the second row from the top to the bottom row, vertical asymmetry may be achieved by making at least one of the thickness of the corresponding layers, the material of the corresponding layers, and the number of conductor layers 13 different. If 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 specifically identified.

[0118] In the second and third rows from the top in Figures 3 and 8, the thickness of the first cover 9A (or, from another viewpoint, the thickness of the first ceramic layer 11A in the region where the first conductor layer 13A is not placed) is increased along with 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 relating to terminals) Figure 9 is a perspective view of a capacitor 201 relating to another example. Figure 3 may also be referred to as a diagram showing the D1D3 cross section of the capacitor 201 (main body 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 vertical asymmetry described above may also be applied to such capacitor 201. Although not specifically shown in the diagrams, vertical asymmetry 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 illustrated, other configurations will be described.

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

[0123] The two types of internal electrodes 19, each connected to a different external electrode 5, may be stacked alternately in pairs rather than one at a time. In this case, for example, the thickness of the dielectric layer 17 between two opposing internal electrodes 19 connected to the same external electrode 5 may be thinner than the thickness of the dielectric layer 17 between two opposing internal electrodes 19 connected to different external electrodes 5. As can be seen from this, the multiple dielectric layers 17 do not have to have the same shape and size.

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

[0125] In the example shown in Figure 9, the internal electrode 19 is sandwiched between dielectric layers 17 that extend on both sides (outward) in the D2 direction than the two long sides of the internal electrode 19 parallel to the D1 direction. As a result, the two long sides are not exposed from the -D2 side and the +D2 side of the main body 203. However, the configuration that prevents the long sides from being exposed may also be achieved by stacking other dielectric layers on the -D2 side and the +D2 side of the laminate composed of the dielectric layer 17 and the ceramic layer 11. From another viewpoint, the main body does not need to be a laminated structure in its entirety.

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

[0127] A multilayer electronic component has a functional part (7) in which insulators (e.g., dielectric layers 17) and conductors (e.g., internal electrodes 19) are alternately stacked. In such a configuration, a cover 9 having one or more ceramic layers 11 and one or more conductive layers 13 can be formed, for example, 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] A multilayer ceramic filter may, for example, have an LC circuit. As can be seen from this example, a multilayer electronic component may implement two or more functions (capacitor and inductor). The parts that implement different functions may be different parts in a planar view and / or different parts in a side view.

[0129] The functional part (7) does not have to be vertically symmetrical. Warping may occur due to asymmetry of the functional part. The asymmetry of the two covers 9 may contribute to reducing such warping.

[0130] (6. Summary of Embodiments) Below, 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. Also, for convenience, the reference numerals of one embodiment will be used below. However, the matters described below may be applied to an embodiment other than the one in which the reference numerals are used, as long as no contradictions arise.

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

[0132] Furthermore, the manufacturing method of the capacitor 1 according to the embodiment includes stacking ceramic green sheets (11) to obtain an unfired laminate (main body 3) (first to third layers from the top in Figure 4), and firing the unfired laminate (main body 3) (third layer from the top in Figure 4). The unfired main body 3 has a functional part 7 (for example, in an unfired state), an unfired first cover 9A that overlaps the functional part 7 on the +D3 side, and an unfired second cover 9B that overlaps the functional part 7 on the -D3 side. 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) that are alternately stacked with one or more layers of first ceramic green sheets (11A). The unfired second cover 9B has one or more layers of second ceramic green sheets (11B) and one or more layers of second conductive paste (13B) that are alternately layered with the one or more layers of second ceramic green sheets (11B). The configuration of the unfired first cover 9A and the configuration of the unfired second cover 9B are asymmetrical with respect to the functional part 7.

[0133] In this case, for example, as already mentioned, warping during firing can be reduced. Furthermore, the frequency or phase of structural or electromagnetic vibrations generated or reflected in the first cover 9A and the second cover 9B can be made different from each other, reducing the likelihood of unintended resonance occurring within the functional part 7. In addition, if the functional part 7 is not asymmetrical vertically, asymmetry can be compensated for with respect to warping during the manufacturing process or strength after manufacturing.

[0134] The first cover 9A and the second cover 9B may differ from each other in at least one of the following: the thickness of the corresponding layers (11 and / or 13), the material of the corresponding layers (11 and / or 13), and the number of layers of the conductive layer 13.

[0135] In this case, compared to the case where vertical asymmetry is achieved by the dimensions of the conductor layer 13 in the planar direction, as in the uppermost main body 3A of Figure 8, for example, the likelihood of the conductor layer 13 exerting unintended electromagnetic effects on the functional part 7 is reduced. Alternatively, the possibility of unintended electromagnetic effects is easier to predict. Furthermore, design changes from the standard design (Comparative Example 1) are easier.

[0136] The first cover 9A may be thicker than the 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 previously described, the volume ratio of the conductive paste in the first cover 9A can be relatively increased to reduce warping. Also, since the first cover 9A is made thicker as the first conductor layer 13A is made thicker, the need to thin the first ceramic layer 11A is reduced. As a result, insulation is more easily ensured. Furthermore, design changes from the standard design (Comparative Example 1) or changes in the manufacturing process are easy.

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

[0139] In this case, the vertical asymmetry is achieved at the position furthest from the functional part 7, thus reducing the likelihood of unintended effects occurring in the functional part 7 due to the asymmetry. Furthermore, the further the ceramic green sheet is from the neutral plane of warping (bending), the more likely compressive forces along the layers are to act as warping moments. Such compressive forces can be reduced by increasing the thickness of the outermost conductive layer 13.

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

[0141] In this case, for example, warping in the D3 direction is likely to occur. Therefore, a configuration that can contribute to reducing warping in the embodiment 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. The joined portion may be, for example, the surface opposite to the functional part 7 and the end in a plan view of the base electrode 21, and the end in a plan view of the dummy electrode 23.

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

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

[0145] In this case, for example, the external electrode 5 is formed by a method that does not require a base layer covering its entire surface. Consequently, the asymmetry of the conductive paste (e.g., base electrode 21) for reducing warping can be easily separated from the configuration of the external electrode 5. As a result, it is easy to manufacture a capacitor 1 that is internally asymmetrical but externally symmetrical.

[0146] The average particle diameter of the metal particles 27 constituting the main component of one or more first conductive layers 13A, and the average particle diameter of the metal particles 27 constituting the main component of one or more second conductive layers 13B, may be larger than either the average particle diameter of the ceramic particles 31 constituting the main component of one or more first ceramic layers 11A, or 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, for example, warping can be reduced by the mechanism described with reference to Figure 5.

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

[0149] In this case, for example, the aforementioned effect is more likely to be obtained if the thickness t3A is 1.2 times or more the thickness t3B. Also, if the thickness t3A is 2.5 times or less the thickness t3B, the likelihood of unintended problems arising due to asymmetry is reduced.

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

[0151] In this case, for example, from another perspective, since the base electrode 21 is positioned by replacing a part of the outermost ceramic layer 11, the proportion of the cover 9 occupied by the base electrode 21 is large. As a result, for example, the effect of upper and lower asymmetry due to the difference in configuration between the first base electrode 21A and the second base electrode 21B is likely to become apparent.

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

[0153] In this case, for example, the conductive layer 13 can be said to have a relatively large area. Therefore, for example, the effect of increasing the thickness of the conductive layer 13 is improved.

[0154] In the embodiments described above, capacitors 1 and 201 are examples of electronic components. Direction D3 is an example of a first direction. The +D3 side is an example of a first side. The -D3 side is an example of a second side. Direction D1 is an example of a second direction. Direction D2 is an example of a third direction. The technology described herein is not limited to the embodiments described above and may be implemented in various forms.

[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. An electronic component comprising: a functional part; a first cover overlapping the functional part on a first side in a first direction; and a second cover overlapping the functional part on a second side opposite to the first side, wherein the first cover comprises one or more first ceramic layers and one or more first conductive layers alternately overlapping the one or more first ceramic layers; and the second cover comprises one or more second ceramic layers and one or more second conductive layers alternately overlapping the one or more second ceramic layers, wherein the configuration of the first cover and the configuration of the second cover are asymmetrical with respect to the functional part.

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

3. The electronic component according to claim 1 or 2, wherein the first cover is thicker than the second cover, and the total thickness of the one or more first conductor layers is thicker than the total thickness of the one or more second conductor layers.

4. The electronic component according to any one of claims 1 to 3, wherein the thickness of the first conductor layer located on the first side among the one or more first conductor layers is greater than the thickness of the second conductor layer located on the second side among the one or more second conductor layers.

5. The electronic component according to any one of claims 1 to 4, wherein the thickness of the functional part in the first direction is smaller than the length in the second direction perpendicular to the first direction, and the length in the third direction perpendicular to both the first and second directions.

6. The electronic component according to any one of claims 1 to 5, further comprising: a first external electrode covering the first cover; and a second external electrode covering the second cover, wherein each of the one or more first conductor layers has a portion exposed to the outside of the first cover and joined to the first external electrode; and 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.

7. An electronic component according to any one of claims 1 to 6, further comprising: a first external electrode covering the first cover; and a second external electrode covering the second cover, wherein the first external electrode has a portion in direct contact with the one or more first ceramic layers and does not contain any co-material; and the second external electrode has a portion in direct contact with the one or more second ceramic layers and does not contain any co-material.

8. The electronic component according to any one of claims 1 to 7, wherein the average particle diameter of the metal particles constituting the main component of the one or more first conductive layers and the average particle diameter of the metal particles constituting the main component of the one or more second conductive layers are greater than either the average particle diameter of the ceramic particles constituting the main component of the one or more first ceramic layers or the average particle diameter of the ceramic particles constituting the main component of the one or more second ceramic layers.

9. An electronic component according to any one of claims 1 to 8, wherein the thickness of the first conductor layer, of which one or more first conductor layers are located furthest to the first side and exposed to the first side from the first cover, is 1.2 times or more and 2.5 times or less the thickness of the second conductor layer, of which one or more second conductor layers are located furthest to the second side and exposed to the second side from the second cover.

10. An electronic component according to any one of claims 1 to 9, wherein, among the one or more first conductor layers, the first conductor layer located furthest to the first side and exposed to the first side from the first cover is embedded from the first side in relation to the first ceramic layer located furthest to the first side among the one or more first ceramic layers, and, among the one or more second conductor layers, the second conductor layer located furthest to the second side and exposed to the second side from the second cover is embedded from the second side in relation to the second ceramic layer located furthest to the second side among the one or more second ceramic layers.

11. The electronic component according to any one of claims 1 to 10, wherein the functional part has a plurality of internal electrodes and a plurality of dielectric layers stacked alternately in the first direction, and when viewed through in the first direction, the one or more first conductive layers and the one or more second conductive layers have portions that overlap with regions where the plurality of internal electrodes overlap each other.

12. A method for manufacturing an electronic component, comprising: laminating ceramic green sheets to obtain an unfired laminate; and firing the unfired laminate, wherein the unfired laminate comprises: an unfired functional portion; an unfired first cover overlapping the unfired functional portion on a first side; and an unfired second cover overlapping the unfired functional portion on a second side opposite to the first side; the unfired first cover comprises 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 comprises 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; and the configuration of the unfired first cover and the configuration of the unfired second cover are asymmetrical with respect to the unfired functional portion.

Images