Laminated electronic component

Abstract

To provide a laminated electronic component that improves the adhesion strength of external electrodes to a body part.SOLUTION: In a capacitor being a laminated electronic component, an effective section 13 includes dielectric layers 7 and internal electrodes 9 which are alternately laminated; a cover 15 overlaps the effective section in a lamination direction of the dielectric layers and the internal electrodes; an external electrode 5 covers a side surface along a lamination direction D3 of the effective section and the cover, and is connected to a partial edge section 9c that is a portion of outer edges of the internal electrodes. A first metal layer 23 of the external electrode is a polycrystalline substance and closely adheres to the side surfaces of the effective section and the cover. A second metal layer 25 is a polycrystalline substance that has an average particle size of crystal grains larger than that of the first metal layer, and overlaps the side surfaces of the effective section and the cover from above the first metal layer. In a section of the external electrode that expands in the lamination direction and that is wide in the length of the partial edge section, when a section covering the side surface of the effective section is referred to as a first section 5a, and a section covering the side surface of the cover is referred to as a second section 5b, and an area ratio of the first metal layer in the first section is smaller than an area ratio of the first metal layer in the second section.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to multilayer electronic components such as multilayer ceramic capacitors.

Background Art

[0002] As a multilayer electronic component, for example, a multilayer ceramic capacitor is known (for example, Patent Document 1 below). A multilayer ceramic capacitor has, for example, a main body portion that directly functions as a capacitor and an external electrode for mounting the capacitor on a circuit board or the like. The main body portion has alternately laminated dielectric layers and flat internal electrodes. The edges of the internal electrodes are exposed from the side surface (the surface along the lamination direction) of the main body portion. The external electrode is constituted by, for example, a metal layer that covers the side surface of the main body portion. Patent Document 1 proposes forming an oxide on the external electrode in order to improve the adhesion of the external electrode to the main body portion (ceramics).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] A capacitor according to one aspect of the present disclosure has an active portion, a cover, and an external electrode. The active portion has dielectric layers and internal electrodes that are alternately laminated. The cover overlaps the active portion in the lamination direction of the dielectric layers and the internal electrodes. The external electrode covers a side surface along the lamination direction of the active portion and the cover and is connected to a partial edge portion that is a part of the outer edge of the internal electrode. The external electrode is composed of polycrystals and has a first metal layer that adheres to the side surface of the active portion and the side surface of the cover, and a second metal layer that is composed of polycrystals having an average grain diameter larger than that of the first metal layer and overlaps the side surface of the active portion and the side surface of the cover from above the first metal layer. In a portion of the external electrode that extends in the lamination direction with the length of the partial edge portion as the width, a portion that covers the side surface of the active portion is referred to as a first portion, and a portion that covers the side surface of the cover is referred to as a second portion. At this time, the area ratio of the first metal layer in the first portion is smaller than the area ratio of the first metal layer in the second portion.

Brief Description of the Drawings

[0005]

Figure 1

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Modes for Carrying Out the Invention

[0006] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. Note that the drawings used in the following description are schematic. Therefore, for example, the dimensional ratios on the drawings do not necessarily match the actual ones. Also, the dimensional ratios etc. may not match between the drawings. Specific shapes and / or dimensions etc. may be exaggerated or details may be omitted. However, the above does not deny that the actual shape and / or dimensions may be as shown in the drawings, or the shape and / or dimensional features may be extracted from the drawings.

[0007] Regarding the aspects described relatively later, basically, only the differences from the aspects described relatively earlier will be described. Regarding matters not particularly mentioned, they may be the same as the aspects described earlier or may be analogized from the aspects described earlier. For components corresponding to each other among different aspects, for convenience, even if there are differences, the same reference numerals may be used.

[0008] In the following description, when referring to "rectangle" (or rectangular shape), "square" (or square shape), and "rectangle" (or rectangular shape), the corners thereof may be chamfered by a curved surface or the like as long as the concept of the above shape holds. For example, the corner formed by two sides may be chamfered with a length of 1 / 5 or less, 1 / 10 or less, or 1 / 20 or less of the length of the shorter of the two sides. Of course, when viewed microscopically, the corners may be rounded due to manufacturing accuracy (error). The same applies to other polygons etc.

[0009] (Overview of the Embodiment) FIG. 1 is a perspective view showing a capacitor 1 (an example of a multilayer electronic component) according to the first embodiment. For convenience, a rectangular 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 side. However, in the description of the embodiment, for convenience, the +D3 side is regarded as the upper side, and terms such as the upper surface and the lower surface may be used.

[0010] The capacitor 1 is, for example, a multilayer ceramic capacitor. The capacitor 1 has a substantially rectangular parallelepiped main body 3 and four external electrodes 5 located at the four corners of the main body 3 in a plan view (viewed in the D3 direction). The external electrodes 5 contribute to the electrical connection between the capacitor 1 and other electronic components (e.g., a circuit board not shown).

[0011] FIG. 3 is a cross-sectional view taken along line III-III of FIG. 1. The main body 3 has, for example, an effective portion 13 and two covers 15 overlapping the upper and lower surfaces of the effective portion 13, respectively. The effective portion 13 has a plurality of dielectric layers 7 and a plurality of internal electrodes 9 overlapping alternately. That is, the effective portion 13 directly bears the function as a capacitor. The cover 15 contributes to, for example, improving the strength of the main body 3.

[0012] Among the outer surfaces of the main body 3, the surfaces along the stacking direction (D3 direction) of the plurality of dielectric layers 7 and the plurality of internal electrodes 9 are referred to as side surfaces. A part of the edge of the plurality of internal electrodes 9 (which may be referred to as a partial edge 9c) is exposed from the side surface of the main body 3. The external electrode 5 covers the side surface of the main body 3 and is fixed to the partial edge 9c. Thereby, the internal electrode 9 and the external electrode 5 are electrically connected. The internal electrodes 9 facing each other with the dielectric layer 7 interposed therebetween are connected to different external electrodes 5.

[0013] Of the portion of the external electrode 5 that covers the side surface of the main body 3, the portion that covers the side surface of the effective portion 13 is referred to as the first portion 5a, and the portion that covers the side surface of the cover 15 is referred to as the second portion 5b. At this time, the volume ratio of the oxide phase in the first portion 5a is smaller than the volume ratio of the oxide phase in the second portion 5b. Thereby, for example, the electrical characteristics can be improved.

[0014] More specifically, for example, the oxide phase generally has a higher electrical resistivity compared to the unoxidized phase. Therefore, by reducing the volume ratio of the oxide phase in the first portion 5a, the resistance value between the outside and the internal electrode 9 of the capacitor 1 can be reduced. As a result, for example, reduction of the equivalent series resistance (ESR), improvement of the Q value, reduction of the heat generation amount, and improvement of the high-frequency performance are expected.

[0015] Also, for example, as will be described in detail later, in the examples shown in FIGS. 4 to 6, due to the method of reducing the volume ratio of the oxide phase in the first portion 5a, the reduction of the oxide phase in the first portion 5a does not necessarily result in a reduction of the ESR. However, along with the above method, the fixing strength of the external electrode 5 to the main body 3 is improved. As a result, for example, it is easier to achieve both improvement of the fixing strength and suppression of the increase in the ESR as compared with the aspect of increasing the volume ratio of the oxide phase in the first portion 5a to improve the fixing strength.

[0016] Also, for example, when the main component of the external electrode 5 is copper, the oxide phase exhibits a rectifying action, and thus may make the characteristics of the capacitor 1 unstable. However, since the volume ratio of the oxide phase in the first portion 5a is small, the probability of such inconvenience can be reduced.

[0017] The comparison of the above volume ratios may be made in the length range of the partial edge 9c of the internal electrode 9 in the direction along the outer periphery of the main body 3 (the direction along the outer edge of the dielectric layer 7). Specifically, it is as follows.

[0018] In FIG. 1, on the side surface of the main body 3 on the -D2 side, one partial edge portion 9c joined to the external electrode 5 on the -D1 side and -D2 side is illustrated. In the illustrated example, the length of the partial edge portion 9c (in the D1 direction) is approximately equal to the length of the external electrode 5 in the direction (D1 direction) along the partial edge portion 9c. However, as shown by the two-dot chain line, the external electrode 5 can be extended further to the +D1 side than the length of the partial edge portion 9c. In such a case, in light of the above effects, it is not necessarily reasonable to compare the portion covering the side surface of the effective portion 13 and the portion covering the side surface of the cover 15 over the entire length of the external electrode 5 in the D1 direction.

[0019] Therefore, with respect to the portion of the external electrode 5 that extends in the D3 direction (the stacking direction of the dielectric layer 7) with the length of the partial edge portion 9c as the width (hereinafter, may be referred to as the "target portion 5c"), the volume ratio of the oxide phase may be compared. That is, the above-described first portion 5a may be the portion covering the side surface of the effective portion 13 in the target portion 5c. The second portion 5b may be the portion covering the side surface of the cover 15 in the target portion 5c. Usually, the lengths of the partial edge portions 9c in the plurality of internal electrodes 9 are the same as each other. However, when they are different from each other, the length of the minimum range including all the partial edge portions 9c may be used as the length of the partial edge portion 9c (the width of the target portion 5c).

[0020] The above is the outline of the embodiment. As understood from the above, the capacitor (1) may have various configurations as long as it has the effective portion 13, the cover 15, and the external electrode 5 covering the side surfaces thereof. That is, the overall configuration of the capacitor 1 (the first embodiment) shown in FIG. 1 is merely an example. However, for convenience, hereinafter, the overall configuration of the capacitor 1 will be described, and then, on the premise of the configuration of the capacitor 1, the oxide phase and the like of the external electrode 5 will be described. Thereafter, the overall configurations of other capacitors (the second embodiment, etc.) will also be described.

[0021] Specifically, the embodiments will be described generally in the following order. 1. Configuration of the capacitor according to the first embodiment (FIGS. 1 to 3) 1.1. Overall configuration 1.2. Active part 1.3. Cover 1.3.1. General cover 1.3.2. Insulating layer 1.3.3. Dummy electrode 1.4. Schematic configuration of external electrodes 2. Specific configuration of external electrodes (Figs. 4 to 9) 2.1. Oxide phase 2.2. Pattern of the first metal layer 2.3. Materials and dimensions of the first metal layer and the second metal layer 2.4. Other examples of the specific configuration of the electrodes 2.4.1. Other examples of the partial edges of the internal electrodes (Fig. 8) 2.4.2. Other examples of the laminated structure of the external electrodes (Fig. 8) 2.4.3. Other examples of the pattern of the first metal layer (Fig. 9) 3. Manufacturing method of the capacitor 3.1. Manufacturing procedure of the entire capacitor 3.2. Method for forming the pattern of the first metal layer 3.3. Method for forming a specific shape of the internal electrode 3.4. Method for reducing the volume ratio of the oxide phase 4. Configuration of the capacitor according to other embodiments (Fig. 10) 5. Examples (Fig. 11) 6. Summary of the embodiments

[0022] (1. Configuration of the capacitor according to the first embodiment) (1.1. Overall configuration) The capacitor 1 according to the first embodiment 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 surface on the -D3 side or +D3 side facing an unillustrated circuit board. Then, the four pads of the circuit board and the four external electrodes 5 are joined by an unillustrated conductive bonding material (e.g., solder), respectively, and thus mounted on the circuit board.

[0023] The configuration (internal structure and external shape) of the capacitor 1 is, for example, generally symmetric with respect to a symmetric plane (not shown) that is parallel to the D1D2 plane and passes through the center in the thickness direction of the capacitor 1. Also, the configuration of the capacitor 1 is, for example, rotationally symmetric by 180° when viewed in the D3 direction. Of course, the capacitor 1 may not have such symmetry.

[0024] The shape of the main body 3 is, for example, generally a thin rectangular parallelepiped. This rectangular parallelepiped may be a square (in the example shown in the figure) or a rectangle (excluding squares; the same applies hereinafter) in plan view. In the description of the embodiment, for convenience, the description may be premised on a square without particular notice.

[0025] The specific dimensions of the main body 3 (or the capacitor 1) are arbitrary. To give an example of the dimensions when the capacitor 1 is relatively small, in the main body 3 (or the capacitor 1), the lengths in the D1 direction and the D2 direction are each 300 μm or more and 1000 μm or less, and the thickness in the D3 direction is 30 μm or more and 100 μm or less.

[0026] Note that a plurality of components of the same type (for example, 5, 7, 9, 15, 17, 19, or 21, etc.) may be provided with the same (or corresponding) shape, size, material, and position, etc., for example, without particular notice and without causing contradictions, etc. For example, the plurality of dielectric layers 7 may be configured with the same shape, size, and material, and may overlap each other without excess or deficiency in plan view. Therefore, without particular notice and without causing contradictions, etc., the description of one component may be regarded as common to a plurality of components of the same type. Also, regarding the fact that a plurality of components of the same type may overlap without excess or deficiency in plan view, individual mention may be omitted.

[0027] One layer-like (film-like) component (for example, 5, 7, 9, 17, or 21, etc.) may be entirely composed of one type of material. However, it may also be configured by stacking layers made of different materials.

[0028] (1.2. Active part) The shape of the active part 13 shown in FIG. 3 is, for example, generally a thin rectangular parallelepiped shape. Its planar shape is the same as the planar shape of the main body part 3. The specific thickness of the active part 13 is arbitrary. For example, the thickness of the active part 13 may be 0.2 or more and 0.9 or less of the thickness of the main body part 3 (any thickness is based on the surface of the insulating part).

[0029] The dielectric layer 7 is basically a layered structure having a constant thickness (at least between the internal electrodes 9). The thickness of the dielectric layer 7 may be appropriately set according to the characteristics required for the capacitor 1 and the like. Taking an example of a relatively thin thickness, the thickness between the internal electrodes 9 is 3 μm or less or 1 μm or less. The shape and dimensions of the dielectric layer 7 in plan view are the same as the shape and dimensions of the active part 13 in plan view. The material of the dielectric layer is, for example, ceramics, and its specific type is also arbitrary. The number of layers of the dielectric layer 7 (internal electrodes 9) is arbitrary. Taking an example, it is 10 layers or more and 30 layers or less.

[0030] The internal electrode 9 is a layered structure having a constant thickness. The thickness of the internal electrode 9 is arbitrary. For example, it may be thinner, of the same degree, or thicker than the thickness of the region between the internal electrodes 9 in the dielectric layer 7. The material of the internal electrode 9 is, for example, metal. The specific type of metal is arbitrary, for example, base metal (for example, Ni and Cu).

[0031] FIG. 2 is an exploded perspective view of the capacitor 1. FIG. 2 is schematic for understanding the shape and relative position of the internal electrode 9 and the like. Therefore, in FIG. 2, various layers are shown in a smaller number compared to FIG. 3.

[0032] The internal electrode 9 has, for example, in plan view, a rectangular (square in the illustrated example) electrode body 9a and a pair of lead electrodes 9b extending from a pair of opposite corners of the electrode body 9a. The internal electrode 9 is located inside the outer edge of the dielectric layer 7 and is not exposed from the side surface of the effective portion 13. The pair of lead electrodes 9b reach the outer edge of the dielectric layer 7 and are connected to a pair of external electrodes 5 located at a pair of opposite corners of the main body portion 3.

[0033] In two internal electrodes 9 facing each other across the dielectric layer 7 (adjacent to each other across the dielectric layer 7), a pair of lead electrodes 9b of one internal electrode 9 and a pair of lead electrodes 9b of the other internal electrode 9 are located on different diagonals in plan perspective. And both are connected to a pair of different external electrodes 5.

[0034] The various dimensions of the electrode body 9a and the lead electrode 9b are arbitrary. For example, the length of the lead electrode 9b on one side of the dielectric layer 7 (that is, the length of the partial edge portion 9c) is substantially the same as the length along the above-mentioned one side of the external electrode 5.

[0035] (1.3. Cover) (1.3.1. General Cover) The cover 15 shown in FIG. 3 is provided, for example, on both the upper surface and the lower surface of the effective portion 13. Different from the illustrated example, the cover 15 may be provided on only one of the upper surface and the lower surface of the effective portion 13. The cover 15 is, for example, a layer having a shape and dimensions that overlap the effective portion 13 exactly in plan perspective. The thickness of the cover 15 is substantially constant. Since the ratio of the thickness of the cover 15 to the thickness of the main body portion 3 is the reverse of the ratio of the thickness of the effective portion 13 to the thickness of the main body portion 3 (already described), specific examples of the ratio are omitted.

[0036] Each cover 15 has, for example, at least one (a plurality in the illustrated example) insulating layer 17 and at least one (a plurality in the illustrated example) dummy layer 21 overlapping the insulating layer 17. Each dummy layer 21 has, for example, four dummy electrodes 19 as shown in FIG. 2. The dummy electrodes 19 contribute to, for example, the reinforcement of the cover 15 and / or the improvement of the connection strength between the main body portion 3 and the external electrode 5. Different from the illustrated example, the cover 15 may have only one or more insulating layers 17 (and may not have the dummy layer 21).

[0037] In addition, when the dummy layer 21 is provided, for example, a metal can be deposited on the surface of the dummy layer 21 by electroless plating or electrolytic plating to fabricate the external electrode 5. Also, regardless of the presence or absence of the dummy layer 21, the external electrode 5 can be formed by the dipping method and the printing method.

[0038] The insulating layer 17 and the dummy layer 21 overlap one by one alternately. In other words, the dummy layer 21 is provided at the boundary of all the insulating layers 17. Different from the illustrated example, the dummy layer 21 may be provided only at a part of the plurality of boundaries. For example, the dummy layer 21 may not be provided at one or more boundaries relatively close to the effective portion 13, and may be provided only at one or more boundaries relatively far from the effective portion 13. However, in such a case, two or more insulating layers 17 that are in close contact with each other without interposing the dummy layer 21 may be regarded as one insulating layer 17.

[0039] There may be only one dummy layer 21. FIG. 12 shows an example different from the example of FIG. 3. In this example, on each of the upper and lower surfaces of the main body 3, the dummy layer 21 is a single layer. More specifically, this dummy layer 21 is exposed from the upper or lower surface of the main body 3 and is insulated from the internal electrode 9 by a single insulating layer 17 or a single dielectric layer 7. In the example of FIG. 12, the dummy layer 21 is made thicker than the example of FIG. 3, and has, for example, a thickness of 1 / 2 or more or 2 / 3 or more of the thickness of the cover 15 (of course, it may not have such a thickness). For convenience, in the description of the embodiment, the aspect of FIG. 12 may be assumed without particular notice.

[0040] (1.3.2. Insulating layer) The insulating layer 17 is a layered structure having a substantially constant thickness except for the change in thickness caused by the presence or absence of overlap with the conductor layers (9 and 19). The planar shape of the insulating layer 17 is, for example, the same as the planar shape of the dielectric layer 7. The material of the insulating layer 17 is arbitrary. For example, the material of the insulating layer 17 may be the same as or different from the material of the dielectric layer 7. Also, the material of the insulating layer 17 may be, for example, ceramics or a material other than ceramics.

[0041] The thickness of the insulating layer 17 is arbitrary. For example, the thickness of the insulating layer 17 may be thicker (in the illustrated example), equal to, or thinner than the thickness of the dielectric layer 7 (both being the thickness between the conductor layers or the thickness of the region not overlapping the conductor layers. The same shall apply hereinafter in this paragraph). For example, the thickness of the insulating layer 17 may be 2 times or more, 5 times or more, or 10 times or more the thickness of the dielectric layer 7, and may be 5 μm or more and 20 μm or less.

[0042] In the example of FIG. 3, the uppermost layer of the effective portion 13 is a conductor layer including the internal electrode 9. And the internal electrode 9 in the uppermost layer is covered by the lowermost insulating layer 17 of the upper cover 15. However, as long as the internal electrode 9 in the uppermost layer is insulated from the dummy electrode 19 of the upper cover 15, the configuration at the above boundary may be different from the illustrated example.

[0043] For example, the uppermost layer of the active portion 13 may be the dielectric layer 7. The uppermost dielectric layer 7 and the lowermost insulating layer 17 of the upper cover 15 may overlap, or the uppermost dielectric layer 7 and the lowermost dummy electrode 19 may overlap. Also, all the dielectric layers 7 and all the insulating layers 17 may not be distinguishable from each other in terms of their materials, thicknesses, etc. From another perspective, the boundary between the active portion 13 and the cover 15 may be ambiguous.

[0044] However, in any aspect, the material between the internal electrodes 9 functions as a dielectric related to the increase in capacitance. Also, the material between the uppermost one of the plurality of internal electrodes 9 and the lowermost one of the plurality of dummy electrodes 19 included in the upper cover 15 functions as an insulating layer that insulates the two. From such a perspective, regardless of whether the insulating layer between the uppermost one of the plurality of internal electrodes 9 and the lowermost one of the plurality of dummy electrodes 19 has the same configuration as the insulating layer 17 between the dielectric layers 7 or the dummy layers 21 between the internal electrodes 9, or whether it is a combination of the previous two layers, it may be regarded as the insulating layer 17 of the cover 15.

[0045] Taking the upper cover 15 as an example, the same applies to the lower cover 15. However, the terms "uppermost layer" and "lowermost layer" are mutually replaced.

[0046] (1.3.3. Dummy Electrode) The dummy electrode 19 (in other words, the dummy layer 21) is, for example, a layer having a certain thickness. The material of the dummy electrode 19 is, for example, a metal. The specific type of metal is arbitrary, for example, a base metal (such as Ni and Cu). The material of the dummy electrode 19 may be the same as or different from the material of the internal electrode 9.

[0047] In a plan view, the position, shape, and dimensions of the dummy electrode 19 are arbitrary. In the example of FIG. 2, the dummy electrode 19 is located at the four corners of the dielectric layer 7 in a plan view. From another perspective, the position of the dummy electrode 19 corresponds to the position of the external electrode 5. Also, the planar shape of the dummy electrode 19 is rectangular (more specifically, square). The size of the dummy electrode 19 in a plan view is approximately equal to the size of the external electrode 5 in a plan view.

[0048] The dummy electrode 19 may overlap the electrode body 9a in a plan view (in the illustrated example, it overlaps the corner of the internal electrode 9), or may not overlap. In the latter case, the dummy electrode 19 may be formed, for example, in an L shape along the corners (two intersecting sides) of the dielectric layer 7. When the dummy electrode 19 overlaps the internal electrode 9, for example, since a wide area of the dummy electrode 19 is ensured, the effect of improving the strength by the dummy electrode 19 is enhanced. When the dummy electrode 19 does not overlap the internal electrode 9, for example, the electrical influence of the dummy electrode 19 on the internal electrode 9 is reduced.

[0049] The dummy electrode 19 is exposed, for example, on the side surface of the main body portion 3. This exposed portion is fixed to the external electrode 5. Thereby, the dummy electrode 19 contributes to improving the bonding strength between the main body portion 3 and the external electrode 5. Different from the illustrated example, the dummy electrode 19 may not be connected to the external electrode 5. For example, the dummy electrode 19 may be provided so as not to be exposed from the side surface of the main body portion 3, and may contribute to improving the strength of the main body portion 3 without contributing to improving the connection strength with the external electrode 5.

[0050] The thickness of the dummy electrode 19 is arbitrary. For example, the thickness of the dummy electrode 19 may be thicker (in the illustrated example), the same, or thinner than the thickness of the internal electrode 9. For example, the thickness of the dummy electrode 19 may be 2 times or more, 5 times or more, or 10 times or more the thickness of the internal electrode 9. Also, the thickness of the dummy electrode 19 may be thinner (in the illustrated example), the same, or thicker than the thickness of the insulating layer 17.

[0051] In the example of FIG. 3, a dummy layer 21 is provided on the uppermost layer of the upper cover 15. And the four dummy electrodes 19 are covered by the external electrode 5. Different from the illustrated example, the dummy layer 21 may not be provided on the uppermost layer of the upper cover 15. As described above, since the dummy layer 21 affects the formation method of the external electrode 5, the presence or absence of the uppermost dummy layer 21 may be determined in consideration of such an influence.

[0052] As described above, the layered (film-like) component may be composed of two or more layers. The external electrode 5 may also be composed of two or more layers. In this case, the lower layer of the external electrode 5 and the uppermost dummy electrode 19 may or may not be distinguishable from the viewpoint of thickness and / or material. Therefore, the presence or absence of the dummy electrode 19 may be grasped by the presence or absence of the dummy electrode 19 covering the effective part 13 (dielectric layer 7) from the side opposite to the dielectric layer 17.

[0053] In the illustrated example, in a plan view, the four dummy electrodes 19 overlap the internal electrode 9, and the four dummy electrodes 19 are connected to the external electrodes 5 having different potentials. Therefore, the dummy layer 21 and the internal electrode 9 need to be separated by the dielectric layer 7 and / or the insulating layer 17. However, this is not the case when some or all of the four dummy electrodes 19 do not overlap the internal electrode 9 in a plan view or some or all of the four dummy electrodes 19 are not connected to the external electrode 5.

[0054] (1.4. Schematic Configuration of External Electrode) The external electrode 5 shown in FIG. 1 is, for example, schematically a layered structure that covers the four surfaces (upper surface, lower surface, and two side surfaces) of the main body portion 3 at the corner portion in the plan view of the main body portion 3. Thereby, the connection between one external electrode 5 and one lead-out electrode 9b is made on the two side surfaces of the main body portion 3, and it is also possible to perform surface mounting on either the upper surface or the lower surface of the capacitor 1. If the reduction in practicality is ignored, for example, the external electrode 5 may cover only two surfaces (a combination of the upper surface or the lower surface and one side surface).

[0055] The shape, dimensions, and material of the portions on each surface of the external electrode 5 are arbitrary. Among the external electrodes 5, the planar shape of the portion located on the upper surface or the lower surface of the main body portion 3 is, for example, rectangular (square in the illustrated example). Also, the planar shape and dimensions of the portion of the external electrode 5 located on the side surface of the main body portion 3 are, for example, rectangular with the same lateral length as the portion located on the upper surface or the lower surface. The thickness of the external electrode 5 (film) may be made thicker than the thicknesses of the internal electrode 9 and the dummy electrode 19, for example.

[0056] (2. Specific Configuration of External Electrode) The specific configuration of the external electrode 5 regarding the volume ratio of the oxide phase, etc. will be described. As described above, in the capacitor 1 according to the first embodiment, one external electrode 5 overlaps two side surfaces of the main body portion 3. However, in the following description, for convenience, attention is paid only to the portion that overlaps one side surface of one external electrode 5. On that premise, the number of each part, etc. may be mentioned. Also, the requirements regarding the volume ratio of the oxide phase, etc. for one external electrode 5 need only be satisfied for one side surface. However, they may also be satisfied for the entire two side surfaces.

[0057] As described with reference to FIG. 1 in the description of the outline of the embodiment, the requirements regarding the volume ratio of the oxide phase, etc. need only be satisfied within the range of the length of the partial edge 9c (the target portion 5c of the external electrode 5) in the direction along the outer periphery of the main body portion 3 (D1 direction or D2 direction). However, in the first embodiment, in the above direction, the length of the external electrode 5 and the length of the partial edge 9c are substantially equal. That is, the entire portion of the external electrode 5 located on one side surface may be regarded as the target portion 5c. Therefore, mention of the target portion 5c may be omitted.

[0058] (2.1. Oxide Phase) FIG. 4 is an enlarged view of region R4 in FIG. 3. As shown in this figure, the external electrode 5 has a laminated structure composed of a first metal layer 23 and a second metal layer 25. The first metal layer 23 is in close contact with (or directly overlaps in another perspective) the outer surface (e.g., side surface) of the main body portion 3. The second metal layer 25 overlaps the side surface of the main body portion 3 from above the first metal layer 23. In another perspective, the second metal layer 25 is in close contact with the outer surface of the first metal layer 23.

[0059] FIG. 5 is a view of a part of the portion shown in FIG. 4 as seen from the +D1 side. In other words, FIG. 5 is a view of the external electrode 5 located on the +D1 side and the +D2 side and its surroundings as seen in the direction indicated by arrow a1 in FIG. 1. In FIG. 5, the illustration of the second metal layer 25 is omitted. Also, the internal electrode 9 (more specifically, the partial edge 9c of the lead-out electrode 9b) and the dummy electrode 19, etc., which are not visible because they are covered by the external electrode 5, are shown by dotted lines. Note that FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 5.

[0060] As shown in FIGS. 4 and 5, the first metal layer 23 does not spread continuously (i.e., without gaps) over the region where the external electrode 5 is disposed, but spreads discontinuously. In other words, on the side surface of the main body portion 3, a non-disposed region A1 of the first metal layer 23 is formed. The non-disposed region A1 is mainly located on the side surface of the effective portion 13. In the non-disposed region A1, the second metal layer 25 is in close contact with the side surface of the main body portion 3 instead of the first metal layer 23.

[0061] FIG. 6 is an enlarged view of region R6 in FIG. 4. As shown in this figure, the outer surface (the surface opposite to the main body portion 3) of the first metal layer 23 is oxidized. In another perspective, the first metal layer 23 has a first material layer 23a and a first oxide layer 23b covering the first material layer 23a. The material of the first oxide layer 23b is an oxide of the material constituting the first material layer 23a.

[0062] Similar to the first metal layer 23, the outer surface of the second metal layer 25 is oxidized. From another perspective, the second metal layer 25 has a second material layer 25a and a second oxide layer 25b covering the second material layer 25a. The material of the second oxide layer 25b is the oxide of the material constituting the second material layer 25a.

[0063] As described above, the non - disposed region A1 of the first metal layer 23 is mainly located on the side surface of the effective portion 13 among the side surfaces of the main body portion 3. Therefore, the area ratio of the first oxide layer 23b on the side surface of the effective portion 13 is smaller than the area ratio of the first oxide layer 23b on the side surface of the cover 15. As a result, in the external electrode 5, the volume ratio of the oxide phase in the first portion 5a is smaller than the volume ratio of the oxide phase in the second portion 5b.

[0064] Here, the volume ratio of the oxide phase in the first portion 5a is the ratio of the volume of the oxide phase existing in the first portion 5a to the volume of the external electrode 5 existing in the first portion 5a, and the volume ratio of the oxide phase in the second portion 5b is the ratio of the volume of the oxide phase existing in the second portion 5b to the volume of the external electrode 5 existing in the second portion 5b. Also, the area ratio of the first oxide layer 23b on the side surface of the effective portion 13 is the ratio of the area of the first oxide layer 23b existing in the first portion 5a to the area of the first portion 5a, and the area ratio of the first oxide layer 23b on the side surface of the cover 15 is the ratio of the area of the first oxide layer 23b existing in the second portion 5b to the area of the second portion 5b.

[0065] Note that, for the sake of simplicity of explanation, the first material layer 23a and the first oxide layer 23b are clearly distinguished, but their boundaries do not have to be clear. From another perspective, the first material layer 23a may contain an oxide phase, and conversely, the first oxide layer 23b may contain a phase that is not an oxide phase. The same applies to the second material layer 25a and the second oxide layer 25b.

[0066] As described above, in the capacitor 1 according to the embodiment, the volume ratio of the oxide phase in the first portion 5a is reduced by making the first metal layer 23 discontinuous on the side surface of the active portion 13. In this case, for example, while the external electrode 5 has a laminated structure, the volume ratio of the oxide phase in the first portion 5a can be easily reduced. By making the external electrode 5 have a laminated structure, for example, it is possible to cope with the difference between the inner surface side and the outer surface side regarding the functions required for the external electrode 5. For example, the first metal layer 23 may be one having a high fixing strength with respect to the internal electrode 9 and / or the dielectric layer 7. The second metal layer 25 may be one that can easily secure a thickness in terms of time and / or cost. Examples of the effects of reducing the volume ratio of the oxide phase in the first portion 5a have already been described.

[0067] By making the first metal layer 23 discontinuous in the active portion 13 and / or the cover 15, effects from a different perspective are also achieved. For example, when the first metal layer 23 is made discontinuous, the surface area of the first metal layer 23 becomes relatively large with respect to the volume of the first metal layer 23. Therefore, for example, while reducing the volume of the first metal layer 23, the affinity between the first metal layer 23 and the second metal layer 25 can be improved. Also, for example, the unevenness generated by the first metal layer 23 being discontinuous exhibits an anchor effect. For these reasons, for example, while ensuring the thickness of the external electrode 5 with the relatively inexpensive second metal layer 25, the fixing strength of the external electrode 5 to the main body portion 3 can be improved.

[0068] Whether or not the requirement that the volume ratio of the oxide phase in the first portion 5a is smaller than the volume ratio of the oxide phase in the second portion 5b is satisfied may be determined by an appropriate method. For example, in an aspect where it can be substantially regarded that the thicknesses of the first oxide layer 23b and the second oxide layer 25b are each substantially constant, the volume ratio is defined by the area of the first oxide layer 23b (that is, the surface area of the first metal layer 23). Therefore, by comparing the area ratio of the first metal layer 23 between the first portion 5a and the second portion 5b, it may be determined whether or not the above requirement is satisfied.

[0069] Here, the area ratio of the first metal layer 23 in the first portion 5a is the ratio of the area of the first metal layer 23 present in the first portion 5a to the area of the first portion 5a, and the area ratio of the first metal layer 23b in the second portion 5b is the ratio of the area of the first metal layer 23 present in the second portion 5b to the area of the second portion 5b.

[0070] In the above case, if the area ratio of the first metal layer 23 in the first portion 5a is at least slightly smaller than the area ratio of the first metal layer 23 in the second portion 5b, it may be determined that the above requirements are satisfied. However, considering measurement errors and the like, when the former area ratio is 0.95 or less, or 0.90 or less, or 0.80 or less with respect to the latter area ratio, it may also be determined that the above requirements are satisfied. The area ratio may be specified based on the manufacturing process, or may be specified by analyzing the external electrode 5 after manufacturing. In the latter case, for example, the area ratio may be specified by imaging and analyzing a mirror surface obtained by polishing the surface or cross section of the external electrode 5.

[0071] Even when the magnitude relationship of the volume ratio of the oxide phase is not specified by the area ratio of the first oxide layer 23b, the magnitude relationship may be determined based on the manufacturing process, or may be determined by analyzing the external electrode 5 after manufacturing. In the latter case, for example, an appropriate analyzer for performing qualitative and quantitative analysis of the material may be used. The measurement by the analyzer may be either a physical method or a chemical method, and may be either a destructive method or a non-destructive method. Also, it may be performed on the total amount of each part (5a and 5b), or may be performed on a plurality of extracted parts in each part.

[0072] In addition, when the boundary between the first portion 5a and the second portion 5b is ambiguous, the ambiguous portion may be excluded with the minimum necessary size, and the volume ratios of the oxide phases of both may be compared.

[0073] (2.2. Pattern of the first metal layer) The specific pattern for making the first metal layer 23 discontinuous is arbitrary. In the example shown in FIG. 5, in the effective portion 13, the first metal layer 23 has a plurality of extending portions 23e extending along the D2 direction (a direction intersecting the lamination direction of the dielectric layer 7 and the internal electrode 9). The positions of the plurality of extending portions 23e in the D3 direction (the lamination direction of the dielectric layer 7 and the internal electrode 9) are different from each other. In other words, the plurality of extending portions 23e are separated from each other in the D3 direction. Thereby, the first metal layer 23 is discontinuous in the D3 direction.

[0074] At least one (all in the example of FIG. 5) of the plurality of extending portions 23e has a break A3 in the middle of the D2 direction. From another perspective, the extending portion 23e has a plurality of separated portions 23f separated from each other in the D2 direction. In other words, the first metal layer 23 has a plurality of separated portions 23f separated from each other in the D2 direction and the D3 direction. Thereby, in addition to being discontinuous in the D3 direction, the first metal layer 23 is also discontinuous in the D2 direction.

[0075] The portion that forms a single piece of the first metal layer 23 (the separated portion 23f in the illustrated example) may be a single crystal or a polycrystal. In other words, in the former case, the separated portion 23f may be one in which crystals grow in an island shape. Although not particularly shown, the island-shaped crystals may be even smaller than the separated portion 23f in the illustrated example and may not fit the concept of a portion obtained by dividing the extending portion 23e in the length direction. For example, the particle size of the island-shaped crystals (in other words, crystal grains) may be smaller than the thickness of the internal electrode 9. In the description of the embodiment, for the sake of convenience, unless otherwise specified, the separated portion 23f may be assumed to be a polycrystal.

[0076] The specific positions, shapes, and dimensions of the plurality of extending portions 23e and the plurality of separating portions 23f are arbitrary. In the example of FIG. 5, the extending portion 23e covers a partial edge 9c of the internal electrode 9 (the edge exposed from the effective portion 13) and extends along the partial edge 9c. Further, as shown in FIGS. 4 and 5, the partial edge 9c has a non-exposed portion 9d (reference numeral in FIG. 4) that is not exposed from the side surface of the effective portion 13. The break A3 of the extending portion 23e overlaps the non-exposed portion 9d when viewed in the D1 direction (the normal direction of the first portion 5a).

[0077] Also, in the example of FIG. 5, the shape of the extending portion 23e and the shape of the separating portion 23f are formed in an elongated shape that extends with a generally constant width (the length in the D3 direction). Different from the illustrated example, the shape of the separating portion 23f (or the extending portion 23e) may be an elliptical shape with the D2 direction as the longitudinal direction. Further, the shape of the separating portion 23f may be a shape in which the longitudinal direction cannot be conceptualized (for example, a circular shape) or a shape with the D3 direction as the longitudinal direction.

[0078] Note that when the extending portion 23e (or the separating portion 23f) extends in the D2 direction, for example, the maximum length in the D2 direction may be slightly longer than the maximum length in the D3 direction. However, the former may be two times or more or five times or more the latter.

[0079] Also, when the first metal layer 23 has a plurality of extending portions 23e at different positions in the D3 direction (or when the plurality of extending portions 23e are separated from each other in the D3 direction), the plurality of extending portions 23e do not have to be completely separated from each other. For example, in the case where the extending portion 23e (or the separating portion 23f) is elliptical as described above, the wide portions of adjacent extending portions 23e (separating portions 23f) may be connected to each other.

[0080] The number of breaks A3 in one extending portion 23e is arbitrary and may be one (the illustrated example) or two or more. The length of the break A3 in the D2 direction is also arbitrary. For example, in one extending portion 23e, the total length of one or more breaks A3 may be shorter than the total length of the non-broken portion of the extending portion 23e.

[0081] As described above, in the first embodiment, one external electrode 5 overlaps two side surfaces of the effective portion 13 and is fixed to the partial edges 9c of the internal electrode 9 on the two side surfaces. The two extending portions 23e that are connected to the same internal electrode 9 and are located on the two side surfaces may or may not be connected to each other (refer to the first, third, and fifth extending portions 23e from the top in FIG. 5), or may not be connected to each other (refer to the other extending portions 23e in FIG. 5).

[0082] More specific settings of the number and width of the extending portions 23e and the number and length of the gaps A3 may be set, for example, so that the examples of the coverage value of the first metal layer 23 described in the examples to be described later are realized. Specifically, the ratio of the area of the first metal layer 23 covering the region (the first region) covered by the first portion 5a of the side surface of the effective portion 13 may be, for example, 50% or more and 95% or less. Then, the number and width of the extending portions 23e and the number and length of the gaps A3 may be set so that this area ratio is realized.

[0083] (2.3. Materials and Dimensions of the First Metal Layer and the Second Metal Layer) The thicknesses of the first metal layer 23 and the second metal layer 25 are arbitrary. For example, the thickness of the first metal layer 23 (for example, the maximum thickness. In this paragraph, the same applies hereinafter) may be 0.2 μm or more and 3 μm or less. The thickness of the second metal layer 25 (for example, the minimum thickness on the first metal layer 23. In this paragraph, the same applies hereinafter) may be 2 μm or more and 10 μm or less. The second metal layer 25 may be made thicker than the first metal layer 23. For example, the thickness of the second metal layer 25 may be 1.5 times or more or 10 times or more the thickness of the first metal layer 23.

[0084] The materials of the first metal layer 23 and the second metal layer 25 are arbitrary. For example, the materials of the first material layer 23a and the second material layer 25a or their main components may be base metals. The base metal may be, for example, Cu, Ni, or an alloy containing at least one of Cu and Ni (e.g., Cu-Ni alloy). The main component may be, for example, a component that occupies 60% by mass or more or 80% by mass or more of the material (the same applies to those other than the first metal layer 23 and the second metal layer 25). When the material is Cu, Ni, or a Cu-Ni alloy, unintended impurities may be present. The impurities may be, for example, less than 1% by mass of the material. The materials of the first oxide layer 23b and the second oxide layer 25b or their main components may be oxides of the materials exemplified above. For example, the oxide may be Cu 2 O, CuO, NiO, or Ni 2 O 3 and so on.

[0085] The materials of the first metal layer 23 and the second metal layer 25 or their main components may be the same as each other or different from each other. The sameness or difference of the materials may be, for example, based only on the component ratio of the elements, or may be based on the component ratio of the elements and also on the grain size of the crystal grains, etc. (the same applies to those other than the first metal layer 23 and the second metal layer 25). Note that even if the elements, grain size, etc. of the first metal layer 23 and the second metal layer 25 are the same as each other, in the configuration illustrated in FIG. 6, it can be confirmed that the first metal layer 23 and the second metal layer 25 exist due to the first oxide layer 23b. The material of at least one of the first metal layer 23 and the second metal layer 25 or its main component may be the same as or different from the material of the internal electrode 9 or its main component.

[0086] FIG. 7 is an enlarged view of region R7 in FIG. 6. In this figure, for the first metal layer 23 and the second metal layer 25, crystal grains are represented for the first metal layer 23 and the second metal layer 25. However, the illustration of whether it is an oxide phase or not is omitted. Also, the representation of crystal grains is omitted for parts other than the first metal layer 23 and the second metal layer 25.

[0087] As shown in this figure, the first metal layer 23 and the second metal layer 25 are composed of, for example, polycrystals. That is, the first metal layer 23 has a plurality of first crystal grains 23p, and the second metal layer 25 has a plurality of second crystal grains 25p. The particle sizes of the two may be such that one is larger than the other (the example shown in the figure), or they may be the same as each other. In the example shown in the figure, the particle size of the first crystal grains 23p is smaller than the particle size of the second crystal grains 25p.

[0088] The particle size referred to here may be, for example, the equivalent circle diameter in the cross-section (a two-dimensional image from another perspective) of the metal layers (23 and 25). Also, the particle sizes compared with each other in the first metal layer 23 and the second metal layer 25 may be average particle sizes unless otherwise specified. The average particle size may be, for example, the particle size when the area ratio reaches 50% when the areas are integrated in order from the smallest particle size in the above two-dimensional image. That is, the average particle size may be the average value based on the area. The particle sizes of the first metal layer 23 and the second metal layer 25 may be regarded without distinguishing whether there is an oxide phase or not.

[0089] The specific values of the particle size of the first crystal grains 23p and the particle size of the second crystal grains 25p and the difference between the two are arbitrary. For example, the average particle size of the first crystal grains 23p may be less than 1 μm, and more specifically, it may be 0.1 μm or more and less than 1 μm. Also, the average particle size of the second crystal grains 25p may be 1 μm or more, and more specifically, it may be 1 μm or more and less than 10 μm. The average particle size of the second crystal grains 25p may be two times or more or five times or more the average particle size of the first crystal grains 23p.

[0090] The particle size may be measured, for example, by mirror-polishing the surface or cross-section of the metal layers (23 and 25), appropriately performing chemical etching to clarify the grain boundaries, and imaging the mirror surface with an electron microscope. More specifically, for example, the first metal layer 23 is imaged at a scale where 30 or more and 50 or less first crystal grains 23p are included. Also, the second metal layer 25 is imaged at a scale where 30 or more and 50 or less second crystal grains 25p are included. Note that the scales of the two may be different from each other. Then, known image processing is performed on the images of the respective metal layers to calculate the equivalent circle diameter. A plurality of images may be taken until the variation due to the imaging position converges, and the average value of the average particle sizes may be obtained.

[0091] Note that, different from the above, there may be a case where it is desired to confirm the presence of the first metal layer 23 and the second metal layer 25 by specifying that there are regions where the sizes of the crystal grains are different from each other. In such a case, for example, in an aspect where the difference in the particle sizes of the first crystal grains 23p and the second crystal grains 25p is large as shown in FIG. 7, the presence of the difference in the particle sizes is specified by visually observing the image, and thus, the presence of the first metal layer 23 and the second metal layer 25 can be confirmed. In other aspects, for example, while appropriately changing the scale so that 30 or more and 50 or less crystal grains are included, imaging of a plurality of continuous regions is performed and the particle size (equivalent circle diameter) of each crystal grain is measured. Then, the change in the particle sizes of the crystal grains located on a predetermined straight line spanning a plurality of regions may be analyzed to confirm the presence of the first metal layer 23 and the second metal layer 25. For example, when obtaining the moving average of the particle sizes of 5 or 10 consecutive crystal grains along the straight line, the presence of the first metal layer 23 and the second metal layer 25 can be confirmed when the particle size at the peak (the second metal layer 25) is 2 times or more or 5 times or more the particle size at the valley (the first metal layer 23).

[0092] (2.4. Other examples of the specific configuration of the electrode) Hereinafter, other examples of the specific configurations of the internal electrode 9 and the external electrode 5 are shown. Note that the examples already described and the other examples to be described hereinafter may be appropriately combined.

[0093] (2.4.1. Other examples of the partial edge of the internal electrode) FIG. 8 is a view showing another example of the internal electrode 9 and the external electrode 5, and corresponds to FIG. 4.

[0094] In the internal electrode 9, the thickness of the partial edge portion 9c (the portion exposed from the side surface of the effective portion 13) may be thicker than the portion inside the partial edge portion 9c. From another viewpoint, the exposed area of the partial edge portion 9c to the outside may be increased. The first metal layer 23 may cover the entire thickness of the partial edge portion 9c. That is, the adhesion area between the partial edge portion 9c and the first metal layer 23 may be expanded in the thickness direction (D3 direction) of the internal electrode 9 as compared with the embodiment of FIG. 4. Hereinafter, the partial edge portion 9c thickened as described above may be referred to as an extended edge portion 9e.

[0095] In the illustrated example, only two types of edge portions, namely, the extended edge portion 9e and the non-exposed portion 9d described above, are shown as the edge portions constituting the partial edge portion 9c. However, these three types of edge portions, namely, these edge portions and an edge portion having the same thickness as the thickness of the portion inside the internal electrode 9 (see FIG. 4; hereinafter referred to as "normal edge portion 9f"), may be provided as appropriate. For example, as embodiments other than the embodiments shown in FIGS. 4 and 9, there are embodiments in which the above three types of edge portions are provided, embodiments in which the normal edge portion 9f and the extended edge portion 9e are provided, embodiments in which only the normal edge portion 9f is provided, and embodiments in which only the extended edge portion 9e is provided. In an embodiment in which both the normal edge portion 9f and the extended edge portion 9e are provided, they may be provided on different partial edge portions 9c or on the same partial edge portion 9c.

[0096] The specific shape and dimensions of the extended edge portion 9e are arbitrary. In the illustrated example, the extended edge portion 9e has a shape that gradually thickens by an equal amount on both sides in the vertical direction as it goes towards the outside (the side of the external electrode 5). Examples of other shapes include, for example, a shape that thickens only upwards or downwards, a shape that thickens on both sides in the vertical direction but the amount of thickening on one side is greater than the amount of thickening on the other side, a shape that does not gradually thicken but has steps, and / or a shape that thickens by bending the edge of the internal electrode 9. The thickness (e.g., the maximum thickness) of the extended edge portion 9e may be, for example, 1.2 times or more, 1.5 times or more, or 2 times or more the thickness of the portion on the inner side of the internal electrode 9.

[0097] (2.4.2. Other examples of the laminated structure of the external electrode) The external electrode 5A shown in FIG. 8 is obtained by adding a third metal layer 27 and a fourth metal layer 29 to the external electrode 5 shown in FIG. 4. The third metal layer 27 and the fourth metal layer 29 contribute to, for example, reducing the solder erosion of the second metal layer 25, reducing the oxidation of the second metal layer 25, and / or improving the bonding strength to the bonding material (e.g., solder). Only one of the third metal layer 27 and the fourth metal layer 29 may be provided, or another metal layer may be further provided. The materials and thicknesses of the third metal layer 27 and the fourth metal layer 29 may be appropriately set according to the purposes of these layers. For example, as described above, in an embodiment where the first metal layer 23 and the second metal layer 25 are Cu, the third metal layer 27 may be Ni and the fourth metal layer 29 may be Sn.

[0098] Note that in FIG. 8, the external electrode 5A is combined with the internal electrode 9 having the extended edge portion 9e and the non-exposed portion 9d. However, it is obvious that the external electrode 5A may be combined with the internal electrode 9 that does not have the extended edge portion 9e and / or the non-exposed portion 9d.

[0099] (2.4.3. Other examples of the pattern of the first metal layer) FIG. 9 is a diagram showing another example of the pattern of the first metal layer 23 and corresponds to FIG. 5.

[0100] In the example of FIG. 9, the extending portion 23e does not have a break A3. In other words, although the first metal layer 23 is discontinuous in the D3 direction (lamination direction), it is continuous in the D2 direction (direction intersecting the lamination direction). Further, the partial edge 9c of the internal electrode 9 does not have a non-exposed portion 9d.

[0101] It is clear that the partial edge 9c shown in FIG. 9 may be a normal edge 9f (FIG. 4) or an extended edge 9e (FIG. 8) or a combination thereof. Further, although it depends on the method of forming the pattern of the first metal layer 23 (described later), the first metal layer 23 having the pattern shown in FIG. 9 may be combined with the non-exposed portion 9d.

[0102] (3. Method of manufacturing capacitor) (3.1. Manufacturing procedure of the entire capacitor) The method of manufacturing the capacitor 1 may be various methods. For example, the general procedure may be the same as a known procedure. An example is shown below.

[0103] First, a ceramic green sheet that becomes the dielectric layer 7 and the insulating layer 17 is produced. Next, a conductive paste that becomes the internal electrode 9 or the dummy electrode 19 is applied (for example, printed) on the ceramic green sheet. Next, the ceramic green sheets are laminated to produce a laminate that becomes the main body portion 3. Note that the lamination of the laminate that becomes the effective portion 13 and the lamination of the portion that becomes the cover 15 for the laminate may be performed together or separately.

[0104] Up to the production of the above laminate, for example, it is performed with the size of a mother substrate on which a large number of a plurality of main body portions 3 are taken. After the production of the laminate, the mother substrate including the laminate is individualized (for example, cut) to a size corresponding to the size of the main body portion 3. Next, the laminate having the size of the main body portion 3 is fired. Thereafter, a metal film is formed on the main body portion 3 to form the external electrode 5.

[0105] Degreasing may be performed before firing. Firing may be performed, for example, in a reducing atmosphere. Reoxidation heat treatment may be performed after firing. Polishing (e.g., barrel polishing) of the main body portion 3 may be performed before and / or after firing. In 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. By polishing, partial edge portions 9c of the internal electrodes 9 and edges of the dummy electrodes 19 may be exposed from the side surfaces of the main body portion 3.

[0106] (3.2. Method of forming a pattern of the first metal layer) There is no particular limitation on the method for making the first metal layer 23 discontinuous. The following is an example.

[0107] Metal may be deposited by electroless plating or electrolytic plating on the surfaces of the internal electrodes 9 and dummy electrodes 19 that are exposed to the outside of the main body 3 (hereinafter, sometimes referred to as "exposed surfaces"), thereby forming the first metal layer 23. In this case, the pattern of the first metal layer 23 is based on the patterns of the exposed surfaces of the internal electrodes 9 and dummy electrodes 19. Therefore, by forming the patterns of the exposed surfaces of the internal electrodes 9 and dummy electrodes 19 into an appropriate shape and by preventing the metal deposited on the exposed surfaces from being connected via the non-placement areas of the exposed surfaces, the first metal layer 23 can be formed into an arbitrary pattern.

[0108] 4 and 5, for example, in the D3 direction, the gap between the exposed surfaces of the multiple dummy electrodes 19 is made smaller than the gap between the exposed surfaces of the multiple internal electrodes 9. Then, the plating conditions (e.g., deposition time) are adjusted so that the deposited metal connects between the exposed surfaces of the multiple dummy electrodes 19 and does not connect between the exposed surfaces of the multiple internal electrodes 9. In this way, a first metal layer 23 having multiple extensions 23e is formed.

[0109] Also, for example, the above-described non-exposed portion 9d is provided at the partial edge 9c of the internal electrode 9. That is, the exposed surface of the internal electrode 9 is interrupted midway. Then, the plating conditions (for example, the deposition time) are adjusted so that the metal deposited on the exposed surface of the internal electrode 9 does not connect beyond the interruption of the exposed surface. As a result, an extending portion 23e having an interruption A3 is formed. When the non-exposed portion 9d is provided at a position where adjacent extending portions 23e are likely to connect, the non-exposed portion 9d also makes it difficult for the plurality of extending portions 23e to connect to each other.

[0110] In addition to the above, various methods are possible for making the first metal layer 23 discontinuous. For example, the first metal layer 23 may be formed through a mask, or etching may be performed through a mask after the formation of the first metal layer 23. The etching may be performed, for example, by laser processing or blasting. As can be understood from this, the first metal layer 23 does not necessarily have to cover the exposed surface (partial edge 9c) of the internal electrode 9, nor does it necessarily have to have a pattern corresponding to the pattern of the exposed surface of the internal electrode 9. Further, the first metal layer 23 may be formed by a method other than electroless plating and electrolytic plating (for example, sputtering).

[0111] When the first metal layer 23 is formed by electroless plating or electrolytic plating, either may be used. For example, the first metal layer 23 may be formed by electroless plating. Also, the second metal layer 25 may be formed by electrolytic plating. By doing so, for example, while improving the adhesion strength between the internal electrode 9 and the first metal layer 23, the thickness of the second metal layer 25 can be ensured in a short time and / or at low cost.

[0112] (3.3. Method for Forming a Specific Shape of the Internal Electrode) The method for forming the non-exposed portion 9d of the internal electrode 9 (partial edge 9c) is arbitrary.

[0113] For example, a non-exposed portion 9d may be formed depending on the pattern when printing a conductive paste to be the internal electrode 9 on a ceramic green sheet. That is, in a plan view of the internal electrode 9, instead of making the shape of the partial edge portion 9c a straight line parallel to the edge of the dielectric layer 7, a non-exposed portion 9d may be formed by making the shape have a portion away from the edge of the dielectric layer 7.

[0114] And / or, for example, after firing (or before firing), the side surface of the effective portion 13 (dielectric layer 7 (or insulating layer 17)) may be partially removed to partially expose the partial edge portion 9c. That is, the portion of the partial edge portion 9c located in the region of the side surface of the effective portion 13 where removal is not performed may be the non-exposed portion 9d. The removal may be performed, for example, by a blast treatment or a laser treatment, and a mask may also be used.

[0115] Note that, as described above, barrel polishing may be performed before and / or after firing. In barrel polishing, the chip (main body portion 3) is accommodated in a barrel, and polishing is performed by rotating the barrel or the like. Therefore, the ridge line portion of the main body portion 3 is easily chamfered, and thus, the dummy electrode 19 is more likely to be exposed on the outer surface of the main body portion 3 than the internal electrode 9. As a result, when a metal is deposited on the exposed surfaces of the internal electrode 9 and the dummy electrode 19 to form the first metal layer 23, the first metal layer 23 is more likely to continuously spread in the dummy electrode 19 than in the internal electrode 9.

[0116] The method of forming the extended edge portion 9e (FIG. 8) of the internal electrode 9 is also arbitrary. For example, the extended edge portion 9e may be formed by stretching and deforming the internal electrode 9 by a blast treatment after firing (or before firing). The blast treatment may also serve as the treatment for partially removing the side surface of the above-described effective portion 13. Further, the extended edge portion 9e may be formed by making only the portion to be the extended edge portion 9e thicker when applying the conductive paste to be the internal electrode 9.

[0117] When the blasting process is performed for partial removal of the side surface of the active part 13 and / or formation of the extended edge part 9e, the material of the powder projected and the projection direction of the powder are arbitrary. For example, the projection direction may be inclined in the D3 direction with respect to the normal line of the side surface of the active part 13. In this case, for example, it is facilitated to extend and deform the edge of the internal electrode 9 in the D3 direction. The specific magnitude of the inclination angle is arbitrary.

[0118] (3.4. Method for reducing the volume ratio of the oxide phase) In the external electrode 5, the method of making the volume ratio of the oxide phase in the first part 5a (the part covering the active part 13) smaller than the volume ratio of the oxide phase in the second part 5b (the part covering the cover 15) may be realized, as understood from the above description, by making the area ratio of the first metal layer 23 in the first part 5a smaller than the area ratio of the first metal layer 23 in the second part 5b. The method of making the area ratio of the first metal layer 23 in the first part 5a smaller is realized, as described above, by making the first metal layer 23 into an appropriate pattern.

[0119] The first oxide layer 23b is formed, for example, by exposing the first metal layer 23 to an oxidizing atmosphere after forming the first metal layer 23 with the material of the first material layer 23a and before forming the second metal layer 25. At this time, by adjusting the time of exposure to the oxidizing atmosphere and the like, the thickness of the first oxide layer 23b (in another aspect, the volume ratio of the oxide phase in the first metal layer 23) may be adjusted. Also, an oxidizing agent or a reducing agent may be used to adjust the volume ratio of the oxide phase.

[0120] Similarly, the second oxide layer 25b is formed by exposing the second metal layer 25 to an oxidizing atmosphere after forming the second metal layer 25 with the material of the second material layer 25a. When the third metal layer 27 is provided, by adjusting the time of exposure of the second metal layer 25 to the oxidizing atmosphere and the like, the thickness of the second oxide layer 25b (in another aspect, the volume ratio of the oxide phase in the second metal layer 25) may be adjusted. Also, an oxidizing agent or a reducing agent may be used to adjust the volume ratio of the oxide phase.

[0121] The method of making the volume ratio of the oxide phase in the first part 5a smaller than the volume ratio of the oxide phase in the second part 5b is not limited to adjusting the area ratio of the first metal layer 23. From another perspective, the first metal layer 23 does not have to spread discontinuously, and may spread without gaps.

[0122] For example, the first metal layer 23 may be formed without gaps over the entire area of the side surface of the main body 3 to be covered by the external electrode 5. Then, after the first oxide layer 23b is formed and before the second metal layer 25 is formed, the first oxide layer 23b may be removed using a reducing agent for part or all of the side surface of the effective part 13 in the above region.

[0123] Also, for example, the first part 5a may be formed after the second part 5b is formed. And after the second part 5b is formed and before the first part 5a is formed, an oxide phase may be formed in the region on the main body 3 side of the second part 5b by performing a heat treatment. In this case, for example, the fixing strength of the second part 5b to the main body 3 is improved by the oxide phase of the second part 5b.

[0124] (4. Structure of the capacitor according to other embodiments) FIG. 10 is a perspective view of a capacitor 201 according to the second embodiment. In the following description, FIG. 3 according to the first embodiment may be referred to as a cross-sectional view taken along line IIIB-IIIB of FIG. 10. However, the reference numerals 1 and 3 in FIG. 3 are replaced with reference numerals 201 and 203. Also, note that FIG. 3 does not necessarily match FIG. 10 in terms of the specific dimensions of each part.

[0125] Generally speaking, the capacitor 201 is different from the capacitor 1 of the four-terminal type in that it is of the two-terminal type. In other words, in the capacitor 201, the basic configuration for functioning as a capacitor is the same as that of the capacitor 1, and the volume ratio of the oxide phase in the first part 5a is also smaller than the volume ratio of the oxide phase in the second part 5b, which is the same as that of the capacitor 1. Specifically, it is as follows.

[0126] The shape of the main body 203 (or the capacitor 201) is, for example, generally rectangular parallelepiped. This rectangular parallelepiped may have, for example, a height (length in the D3 direction) equal to the width (length in the D2 direction) (example shown in the figure), or may be smaller. The length of the rectangular parallelepiped in the length direction (D1 direction) is, for example, larger than the width. The dimensions of the main body 203 are arbitrary. To give an example of relatively small dimensions, the length is 0.4 mm or more and 3.2 mm or less, and the width and height are 0.2 mm or more and 2.5 mm or less. The external electrode 5 is generally a layered structure that covers the end portions in the longitudinal direction of the main body 203 over five faces of the rectangular parallelepiped.

[0127] Similar to the first embodiment (see FIG. 3), the main body 203 has an effective portion 13 and a cover 15. The effective portion 13 is formed by alternately laminating a dielectric layer 7 and an internal electrode 9. The cover 15 has at least one insulating layer 17 and at least one dummy layer 21. The dummy layer 21 includes a plurality of dummy electrodes 19.

[0128] However, the position and shape of the internal electrode 9 in plan view are different from those in the first embodiment. Specifically, for example, in plan view, the shape of the internal electrode 9 is generally a rectangle having four sides parallel to the four sides of the rectangle of the main body 203 (dielectric layer 7). Of the four sides of the internal electrode 9, two long sides and one short side are located inside the side surface of the main body 203 (not exposed). The remaining one short side is exposed from the side surface of the main body 203 on the +D1 side or -D1 side and is connected to the external electrode 5 on the +D1 side or -D1 side. The internal electrodes 9 connected to different external electrodes 5 are alternately laminated. The region of the internal electrode 9 that overlaps with other internal electrodes 9 in plan view is the electrode main body 9a. The portion extending from the electrode main body 9a to the external electrode 5 is the lead-out electrode 9b.

[0129] The position and shape of the dummy electrode 19 in the plane may be different from those in the first embodiment. Specifically, for example, in a plan view, each dummy layer 21 has two dummy electrodes 19 at both ends in the longitudinal direction of the main body portion 203. The dummy electrode 19 has a rectangular shape extending over the entire width (length in the D2 direction) of the main body portion 203. For example, it is exposed from the side surface on the +D1 side or -D1 side of the main body portion 203, and is also exposed from the side surfaces on the +D2 side and -D2 side.

[0130] As described with reference to FIG. 1 in the description of the outline of the embodiment, the requirements regarding the volume ratio of the oxide phase and the like may be satisfied within the range of the length of the partial edge 9c of the internal electrode 9 (the target portion 5c of the external electrode 5). Therefore, regarding the above requirements, among the external electrodes 5, the portions covering the upper and lower surfaces, the surface on the +D2 side, and the surface on the -D1 side of the main body portion 203 may be ignored. Further, when focusing on the portion of the external electrode 5 that covers the side surface on the +D1 side (or -D1 side), the portion that covers the so-called side margin portion from the +D1 side (or -D1 side) may also be ignored. The side margin portion is the portion of the main body portion 203 from the edge on the +D2 side (or -D2 side) of the internal electrode 9 to the side surface on the +D2 side (or -D2 side) of the main body portion 203.

[0131] Although not particularly shown, other examples of the configuration of the capacitor will be given.

[0132] The capacitor may have a packaging resin that covers the entire structure illustrated in FIG. 1 or FIG. 10, and lead wires that are connected to the external electrode 5 and extend from the packaging resin. From another perspective, the capacitor may not be a surface mount type but a through-hole mount type. In such an aspect, one external electrode 5 may cover only one side surface.

[0133] The two types of internal electrodes 9 connected to the different external electrodes 5 may be alternately laminated not one by one but two by two. In this case, for example, the thickness of the dielectric layer 7 between the internal electrodes 9 connected to the same external electrode 5 and facing each other may be made thinner than the thickness of the dielectric layer 7 between the internal electrodes 9 connected to the different external electrodes 5 and facing each other. As can be understood from this, the plurality of dielectric layers 7 do not have to have the same shape and size as each other.

[0134] Also, the two types of internal electrodes 9 connected to the different external electrodes 5 do not have to face each other. For example, the two types of internal electrodes 9 connected to the different external electrodes 5 are provided in the same layer, and by providing the internal electrodes 9 facing the two types of internal electrodes 9, a circuit in which two parallel plate capacitors are connected in series may be configured. Also, a circuit in which three or more parallel plate capacitors are connected in series may be configured.

[0135] In the second embodiment, the side margin portion was touched upon. The side margin portion is constituted by, for example, a portion of the dielectric layer 7 that extends to the +D2 side or the -D2 side with respect to the internal electrode 9. However, the side margin portion may be constituted by stacking another dielectric layer on the side surface of the laminate constituted by the dielectric layer 7 on the +D2 side or the -D2 side. From another point of view, it is not necessary for the entire body portion 203 to have a laminated structure.

[0136] (5. Example) FIG. 11 is a chart showing the results of prototyping a capacitor according to the embodiment (more specifically, the capacitor 201 according to the second embodiment) and examining its characteristics. In this figure, for example, it is shown that by making the first metal layer 23 discontinuous and reducing the volume ratio of the oxide phase in the first portion 5a, it is possible to achieve both an improvement in adhesion strength and a reduction in ESR. Specifically, it is as follows.

[0137] In this figure, "No." is the identification number assigned to the examples and comparative examples. As can be understood from the description below, No.1 to No.6 are examples, and No.7 is a comparative example.

[0138] "First metal layer coverage" indicates the area ratio (%) of the first metal layer 23 in the region where the target portion 5c of the external electrode 5 should overlap (i.e., the region where the first portion 5a should be formed) among the side surfaces of the effective portion 13, except for No.8. "Second metal layer coverage" indicates the area ratio of the second metal layer 25 in the above region. Hereinafter, for convenience, the mention that the above area ratio is in the region where the target portion 5c should overlap may be omitted, and it may simply be referred to as the area ratio on the side surface of the effective portion 13, etc.

[0139] "Electrode peeling (number)" indicates the number of peeled external electrodes 5 as a fraction in the experiment on 100 samples. "ESR (mΩ)" indicates the measured value of ESR.

[0140] Although not shown in FIG. 11, in any of the examples (No.1 to No.8), the first metal layer 23 and the second metal layer 25 were each formed on the entire surface of the region where the target portion 5c of the external electrode 5 should overlap among the side surfaces of the cover 15. That is, in the second portion 5b, the area ratio of each layer is 100%, and from another perspective, the area ratios of the two layers are the same as each other.

[0141] As shown in FIG. 11, in the examples (No.1 to No.6), the area ratio of the first metal layer 23 on the side surface of the effective portion 13 is less than 100% (specifically, 40% or more and 95% or less). Also, the area ratio of the second metal layer 25 on the side surface of the effective portion 13 is 80% or more and 100% or less. From another perspective, in the first portion 5a, the area ratio of the first metal layer 23 is made smaller than the area ratio of the second metal layer 25.

[0142] In the second part 5b, since the area ratios of the first metal layer 23 and the second metal layer 25 are the same, in the examples (No. 1 to No. 6) where the area ratio of the first metal layer 23 in the first part 5a is smaller than the area ratio of the second metal layer 25, the volume ratio of the oxide phase in the first part 5a is smaller than the volume ratio of the oxide phase in the second part 5b.

[0143] In No. 7 (comparative example), the area ratios of the first metal layer 23 and the second metal layer 25 on the side surface of the effective part 13 are both 100%. From another perspective, in the first part 5a, similar to the second part 5b, the area ratios of the two layers are the same as each other. Therefore, the volume ratio of the oxide phase in the first part 5a is the same as the volume ratio of the oxide phase in the second part 5b.

[0144] In No. 8, while intending to form the first metal layer 23 on a relatively large area of the side surface of the effective part 13, an oxidation treatment (a treatment not performed in No. 1 to No. 7) is carried out on the first metal layer 23 to increase the volume ratio of the oxide phase. As a result, in No. 8, compared with other examples (No. 1 to No. 7), the volume ratios of the oxide phases in the first part 5a and the second part 5b are larger.

[0145] The first metal layer 23 is formed by electroless plating, and the second metal layer 25 is also formed by electroless plating. In No. 1 to No. 8, the second metal layers 25 are intended to have the same thickness as each other. In No. 1 and No. 2, due to the small area ratio of the first metal layer 23, the area ratio of the second metal layer 25 does not reach 100%.

[0146] For the experiment on whether electrode peeling occurs, a force of 5 N was applied to the capacitor 201 mounted on the circuit board in the D2 direction (the direction along the surface of the circuit board), and it was examined whether the external electrode 5 peeled off. The ESR was specified based on impedance measurement at 1 MHz.

[0147] The specifications of the capacitor 201 used in the experiment are shown below. ·Length in the D1 direction: 1.0 mm ·Lengths in the D2 and D3 directions: 0.5 mm ·Thickness of the cover 15 (in the D3 direction): 30 μm ·Width of the side margin part (in the D2 direction): 30 μm ·Thickness of the dielectric layer 7: 1.0 μm ·Number of stacked internal electrodes 9: 20 layers

[0148] The number of occurrences of electrode peeling is 0 / 100 when the coverage of the first metal layer 23 is 40% or more and 80% or less (No. 1 to No. 5), and 1 / 100 when it is 95% (No. 6). On the other hand, when the coverage of the first metal layer 23 reaches 100%, the number of occurrences of electrode peeling increases sharply (10 / 100). Therefore, it can be said that when the coverage of the first metal layer 23 is 40% or more and 95% or less (or 40% or more and 80% or less), the effect of reducing electrode peeling is likely to be achieved.

[0149] In the embodiment, as described in the explanation of the first embodiment, a non-exposed portion 9d that is not exposed from the side surface of the main body portion 203 is provided at the partial edge portion 9c of the internal electrode 9 so that the first metal layer 23 does not precipitate, reducing the area ratio of the first metal layer 23. Consequently, the volume ratio of the oxide phase (the first oxide layer 23b) is reduced. Therefore, when the coverage of the first metal layer 23 becomes small, the volume ratio of the oxide phase with high electrical resistivity is reduced, but the cross-sectional area of the connection portion between the internal electrode 9 and the external electrode 5 is decreased. As a result, the smaller the coverage of the first metal layer 23, the higher the ESR.

[0150] However, as can be understood from the comparison with No. 8, the ESR is reduced when compared with the case where oxidation treatment is performed. On the other hand, in No. 8, the adhesion strength of the external electrode 5 to the main body portion 203 is improved by the oxidation treatment, and the number of occurrences of peeling of the external electrode 5 is 0 / 100. Therefore, it can be said that by reducing the area ratio of the first metal layer 23 in the effective portion 13, the adhesion strength can be improved without performing oxidation treatment, enabling both improvement of the adhesion strength and reduction of the ESR.

[0151] Examples of the coverage range of the first metal layer 23 include a range of 40% or more and 95% or less, which is the range in the embodiments. Also, from the perspective of the range where no peeling occurs at all, a range of 40% or more and 80% or less can be mentioned. Since the ESR approximately doubles when the coverage of the first metal layer 23 changes from 50% to 40%, from this perspective, a range of 50% or more and 95% or less can be mentioned. As an overlapping part of the first two perspectives, a range of 50% or more and 80% or less can be mentioned.

[0152] Note that FIG. 11 is based on the capacitor 201 according to the second embodiment and is also based on a sample of the capacitor 201 having specific specifications. However, it is clear that within the above-described range, even if not the best effect, a better effect can be obtained.

[0153] (6. Summary of the Embodiment) As described above, the capacitor 1 (or 201) has the active part 13, the cover 15, and the external electrode 5. The active part 13 has the dielectric layers 7 and the internal electrodes 9 laminated alternately. The cover 15 overlaps the active part 13 in the lamination direction (D3 direction) of the dielectric layers 7 and the internal electrodes 9. The external electrode 5 covers the side surfaces of the active part 13 and the cover 15 along the D3 direction and is connected to a partial edge 9c, which is a part of the outer edge of the internal electrode 9. In a part (target part 5c) of the external electrode 5 that extends in the D3 direction with the length of the partial edge 9c as the width, the part that covers the side surface of the active part 13 is referred to as the first part 5a, and the part that covers the side surface of the cover 15 is referred to as the second part 5b. At this time, the volume ratio of the oxide phase in the first part 5a is smaller than the volume ratio of the oxide phase in the second part 5b.

[0154] In this case, for example, as described in the outline of the embodiment, the ESR can be reduced, the improvement of the adhesion strength of the external electrode 5 and the reduction of the ESR can be achieved simultaneously, and / or the electrical characteristics can be stabilized.

[0155] The external electrode 5 may have a first metal layer 23 and a second metal layer 25. The first metal layer 23 may be in close contact with the side surfaces of the effective portion 13 and the cover 15. The second metal layer 25 may overlap the side surfaces of the effective portion 13 and the cover 15 from above the first metal layer 23. In the first portion 5a, the first metal layer 23 may spread discontinuously. Thereby, a non-arrangement region A1 of the first metal layer 23 may be formed. The second metal layer 25 may be in close contact with the side surface of the effective portion 13 in the non-arrangement region A1.

[0156] In this case, for example, according to the normal metal film formation process, since there is a high probability that a first oxide layer 23b is formed on the surface of the first metal layer 23, by making the first metal layer 23 discontinuous on the side surface of the effective portion 13, the volume ratio of the oxide phase in the first portion 5a can be reduced. Thereby, effects such as the above-described reduction in ESR can be obtained. Also, for example, since the first metal layer 23 is discontinuous, as already described, the adhesion strength between the first metal layer 23 and the second metal layer 25 can be improved. As shown with reference to the examples, it is facilitated to achieve both a reduction in ESR and an improvement in adhesion strength.

[0157] Each of the first metal layer 23 and the second metal layer 25 may be composed of polycrystals. The average grain size of the first crystal grains 23p in the first metal layer 23 may be smaller than the average grain size of the second crystal grains 25p in the second metal layer 25.

[0158] In this case, for example, compared with an aspect in which the average grain size of the first crystal grains 23p is relatively large (such an aspect is also included in the technology according to the present disclosure), the surface area of the first metal layer 23 tends to be large. As a result, the affinity between the first metal layer 23 and the second metal layer 25 is improved, and the adhesion strength between the two is likely to be improved. On the other hand, since the average grain size of the second crystal grains 25p is relatively large, the number of grain boundaries can be reduced. As a result, for example, the probability of moisture intrusion from the outside can be reduced.

[0159] The ratio of the area of the first metal layer 23 covering the first region to the area of the first region covered by the first part 5a on the side surface of the effective portion 13 may be 50% or more and 95% or less.

[0160] In this case, for example, as described with reference to FIG. 11, it is facilitated to achieve both reduction of ESR and improvement of adhesion strength.

[0161] When the first part 5a is viewed in its normal direction, the first metal layer 23 may have a plurality of extending portions 23e extending in a direction (direction D2 in FIG. 5) intersecting the D3 direction at different positions in the stacking direction (D3 direction). Note that the separation portion 23f may also be regarded as a kind of extending portion depending on its shape.

[0162] In this case, for example, since the first metal layer 23 and the second metal layer 25 engage with each other in the stacking direction, it is facilitated to improve the adhesion strength between the two in the D3 direction. Usually, the capacitor 1 (201) often faces the circuit board on which the capacitor 1 is mounted in the D3 direction, and thus, the probability of being peeled off from the circuit board in the D3 direction is high. Therefore, by improving the adhesion strength in the D3 direction, it is facilitated to efficiently improve the strength of the external electrode 5.

[0163] At least one of the plurality of extending portions 23e may have an interruption A3 in the middle in the above-described intersecting direction (direction D2 in FIG. 5).

[0164] In this case, for example, the first metal layer 23 and the second metal layer 25 engage with each other in two directions, the D3 direction and the direction intersecting the D3 direction. As a result, it is facilitated to improve the adhesion strength in various directions.

[0165] The plurality of extending portions 23e may extend along the partial edge portions 9c so as to cover the partial edge portions 9c of the plurality of internal electrodes 9.

[0166] In this case, for example, while making the first metal layer 23 discontinuous, it becomes easier to secure the adhesion area between the first metal layer 23 and the partial edge portion 9c. As a result, for example, the effect of improving the adhesion strength between the internal electrode 9 and the second metal layer 25 by reducing the average particle diameter of the first metal layer 23 described above is likely to be achieved. Further, for example, by forming the first metal layer 23 on the partial edge portion 9c by electroless plating or electrolytic plating, the extending portion 23e can be formed. That is, the first metal layer 23 can be made discontinuous simply.

[0167] In at least one of the plurality of internal electrodes 9, the partial edge portion 9c may have a non-exposed portion 9d (FIG. 4) that is not exposed from the side surface of the effective portion 13 in the middle in the above-described intersecting direction (direction D2 in FIG. 5). The extending portion 23e covering the partial edge portion 9c having the non-exposed portion 9d may have a break A3 at a position overlapping the non-exposed portion 9d.

[0168] In this case, for example, while making the extending portion 23e discontinuous in its extending direction, it becomes easier to secure the adhesion area between the extending portion 23e and the partial edge portion 9c. Further, for example, by forming the first metal layer 23 on the partial edge portion 9c by electroless plating or electrolytic plating, the extending portion 23e having the break A3 can be formed. That is, the extending portion 23e can be made discontinuous in its extending direction simply.

[0169] The thickness of the partial edge portion 9c may be larger than that of the portion of the internal electrode 9 inside the partial edge portion 9c.

[0170] In this case, for example, since the adhesion area between the external electrode 5 (for example, the first metal layer 23) and the partial edge portion 9c becomes large, the adhesion strength between the two can be improved. Further, for example, when the side surface of the dielectric layer 7 is removed by a blasting process to expose the partial edge portion 9c from the side surface of the main body portion 3, while performing the process for such exposure, the internal electrode 9 can be stretched and deformed to thicken the partial edge portion 9c, so that the probability of an increase in the process can be reduced.

[0171] The active portion 13 may have a rectangular shape when viewed in the stacking direction (D3 direction). The cover 15 may have four dummy electrodes 19 and an insulating layer 17. The four dummy electrodes 19 may be located at the four corners of the active portion 13 when viewed through in the D3 direction. The insulating layer 17 may cover the four dummy electrodes 19 from the side opposite to the active portion 13. The four external electrodes 5 may be fixed to the four dummy electrodes 19.

[0172] In this case, for example, the fixing strength of the external electrode 5 to the main body portion 3 can be improved. Also, for example, when forming the first metal layer 23 by electroless plating or electrolytic plating, by depositing a metal on the dummy electrode 19, it is facilitated to form the first metal layer 23 without gaps on the side surface of the cover 15. Since the dummy electrode 19 is located on the diagonal line where it is easy to secure the length in the rectangular main body portion 3, the dummy electrode 19 can be easily moved away from the electrode main body 9a. As a result, it is easy to reduce the influence of the dummy electrode 19 on the characteristics of the active portion 13.

[0173] The technology according to the present disclosure is not limited to the above embodiments and may be implemented in various modes.

[0174] For example, the multilayer electronic component is not limited to a capacitor. For example, in the multilayer electronic component, a part of the internal electrodes may be configured to form a capacitor, and the other part of the internal electrodes may be configured to form an inductor or a resistor. And the multilayer electronic component may form an appropriate circuit (for example, a resonant circuit) as a whole. Also, the multilayer electronic component only needs to have at least a part formed by laminating a dielectric layer and internal electrodes, and does not necessarily have to be entirely or mostly constituted by a laminate.

[0175] From the present disclosure, a concept that does not require the volume ratio of the oxide phase in the first portion 5a to be smaller than the volume ratio of the oxide phase in the second portion 5b may be extracted. For example, a concept characterized in that the first metal layer 23 spreads discontinuously may be extracted, or a concept characterized in that the partial edge 9c of the internal electrode 9 is thicker than the inner portion of the internal electrode 9 may be extracted.

[0176] The following concepts may be extracted from this disclosure. (Concept 1) An active part having dielectric layers and internal electrodes laminated alternately, A cover overlapping the active part in the lamination direction of the dielectric layer and the internal electrode, An external electrode covering side surfaces along the lamination direction of the active part and the cover and connected to a partial edge portion which is a part of the outer edge of the internal electrode, and having In a portion where the external electrode extends in the lamination direction with the length of the partial edge portion as the width, when a portion covering the side surface of the active part is referred to as a first portion and a portion covering the side surface of the cover is referred to as a second portion, the volume ratio of the oxide phase in the first portion is smaller than the volume ratio of the oxide phase in the second portion A multilayer electronic component. (Concept 2) The external electrode has a first metal layer in close contact with the side surfaces of the active part and the cover, and a second metal layer overlapping the side surfaces of the active part and the cover from above the first metal layer, In the first portion, the first metal layer extends discontinuously, thereby forming a non - arrangement region of the first metal layer, and the second metal layer is in close contact with the side surface of the active part in the non - arrangement region The multilayer electronic component according to Concept 1. (Concept 3) Each of the first metal layer and the second metal layer is composed of polycrystals, and the average grain diameter of the crystal grains in the first metal layer is smaller than the average grain diameter of the crystal grains in the second metal layer The multilayer electronic component according to Concept 2. (Concept 4) A ratio of an area of ​​the first metal layer covering the first region to an area of ​​the side surface of the effective portion covered by the first portion is 50% or more and 95% or less. 4. The multilayer electronic component according to claim 2 or 3. (Concept 5) When the first portion is viewed in a normal direction thereof, the first metal layer has a plurality of extending portions extending in a direction intersecting the stacking direction at different positions in the stacking direction. The multilayer electronic component according to any one of Concepts 2 to 4. (Concept 6) At least one of the plurality of extension portions has a discontinuity in the intersecting direction. 6. The laminated electronic component according to claim 5. (Concept 7) The plurality of extension portions extend along the partial edge portions so as to cover the partial edge portions of the plurality of internal electrodes. 7. The multilayer electronic component according to Concept 5 or 6. (Concept 8) In at least one of the plurality of internal electrodes, the partial edge portion has a non-exposed portion that is not exposed from a side surface of the effective portion in the middle in the intersecting direction, The extension portion covering the edge of the portion having the unexposed portion has a discontinuity at a position overlapping the unexposed portion. 8. The laminated electronic component according to claim 7. (Concept 9) The thickness of the partial edge portion is greater than the thickness of a portion of the internal electrode that is more inside than the partial edge portion. The multilayer electronic component according to any one of Concepts 1 to 8. (Concept 10) The effective portion has a rectangular shape when viewed in the stacking direction, The cover is four dummy electrodes located at four corners of the effective portion when viewed in the stacking direction; an insulating layer covering the four dummy electrodes from the side opposite to the effective portion, The four external electrodes are fixed to the four dummy electrodes. The multilayer electronic component according to any one of Concepts 1 to 9.

Explanation of Signs

[0177] 1... capacitor, 5... external electrode, 5a... first part, 5b... second part, 7... dielectric layer, 9... internal electrode, 9c... partial edge.

Claims

1. an active portion having dielectric layers and internal electrodes alternately stacked; a cover overlapping the effective portion in a lamination direction of the dielectric layers and the internal electrodes; an external electrode covering a side surface of the effective portion and the cover along the stacking direction and connected to a partial edge portion that is a part of an outer edge of the internal electrode; It has The external electrode is a first metal layer made of a polycrystalline material and in close contact with a side surface of the effective portion and a side surface of the cover; a second metal layer that is made of a polycrystalline body having a larger average grain size than the first metal layer and that overlaps the first metal layer with a side surface of the effective portion and a side surface of the cover, In a portion of the external electrode that extends in the stacking direction with a width equal to the length of the partial edge portion, a portion covering a side surface of the effective portion is referred to as a first portion, and a portion covering a side surface of the cover is referred to as a second portion, an area ratio of the first metal layer in the first portion is smaller than an area ratio of the first metal layer in the second portion. Multilayer electronic components.

2. In the first portion, The first metal layer extends discontinuously, thereby forming a non-disposed region of the first metal layer; The second metal layer is in close contact with a side surface of the effective portion in the non-disposition region. The multilayer electronic component according to claim 1 .

3. The first metal layer is A material layer; and an oxide layer covering the material layer, the oxide layer being made of an oxide of the material that constitutes the material layer. The multilayer electronic component according to claim 1 or 2.

4. A ratio of an area of ​​the first metal layer covering the first region to an area of ​​the side surface of the effective portion that is covered by the first portion is 50% or more and 95% or less. The multilayer electronic component according to claim 1 .

5. When the first portion is viewed in a normal direction thereof, the first metal layer has a plurality of extending portions extending in a direction intersecting the stacking direction at different positions in the stacking direction. The multilayer electronic component according to claim 1 .

6. At least one of the plurality of extension portions has a discontinuity midway in the intersecting direction. The multilayer electronic component according to claim 5 .

7. The plurality of extension portions extend along the partial edge portions so as to cover the partial edge portions of the plurality of internal electrodes. The multilayer electronic component according to claim 5 .

8. In at least one of the plurality of internal electrodes, the partial edge portion has a non-exposed portion that is not exposed from a side surface of the effective portion in the middle in the intersecting direction, The extension portion covering the edge of the portion having the unexposed portion has a discontinuity at a position overlapping the unexposed portion. The multilayer electronic component according to claim 7 .

9. The thickness of the partial edge portion is greater than the thickness of a portion of the internal electrode that is more inside than the partial edge portion. The multilayer electronic component according to claim 1 .

10. The effective portion has a rectangular shape when viewed in the stacking direction, The cover is four dummy electrodes located at four corners of the effective portion when viewed in the stacking direction; an insulating layer covering the four dummy electrodes from the side opposite to the effective portion, The four external electrodes are fixed to the four dummy electrodes. The multilayer electronic component according to claim 1 .

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