Multilayer electronic component

Abstract

To provide a multilayer electronic component with enhanced adhesion of an external electrode.SOLUTION: In a multilayer ceramic capacitor 1, which is a multilayer electronic component, an active portion 11 includes a dielectric layer 7 and an internal electrode 9 stacked alternately in the stacking direction. A cover 13 overlaps the active portion from a first side in the stacking direction. The base electrode 16 overlaps the cover from the first side. The external electrode 5 overlaps the base electrode from the first side. The base electrode and the external electrode are fixed together by sharing a diffusion layer 21 in which a first metal contained in the base electrode and a second metal contained in the external electrode are mixed together. The diffusion layer is formed across the entire interface BS between the base electrode and the external electrode.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Known examples of multilayer electronic components include multilayer ceramic capacitors (see, for example, Patent Documents 1 and 2 below). Multilayer ceramic capacitors have, for example, a main body that directly functions as a capacitor and external electrodes for mounting the capacitor on a circuit board or the like. The main body has alternately stacked dielectric layers and flat internal electrodes. In Patent Documents 1 and 2, a base electrode is provided that forms the surface of the main body, and a metal layer is deposited on the base electrode by plating, thereby forming the external electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-212298 [Patent Document 2] Japanese Patent Application Publication No. 2023-135456 Summary of the Invention

[0004] A multilayer electronic component according to one aspect of the present disclosure includes an effective portion, a cover, a base electrode, and an external electrode. The effective portion includes dielectric layers and internal electrodes alternately stacked in a stacking direction. The cover overlaps the effective portion from the first side of a first side and a second side in the stacking direction. The base electrode is primarily composed of a first metal and overlaps the cover from the first side. The external electrode is primarily composed of a second metal and overlaps the base electrode from the first side. The base electrode and the external electrode are fixed by sharing a diffusion layer in which the first metal contained in the base electrode and the second metal contained in the external electrode are mixed together, and the diffusion layer is formed across the entire interface between the base electrode and the external electrode. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a perspective view showing a capacitor according to a first embodiment. [Figure 2] FIG. 2 is a schematic exploded perspective view of the capacitor of FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 10 is a perspective view showing a capacitor according to a second embodiment. [Figure 5] 10 is a table showing evaluation results of the capacitor according to the example. [Figure 6] FIG. 10 is a schematic cross-sectional view showing a portion of a capacitor according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0007] Regarding the embodiments described relatively later, basically, only the differences from the embodiments described relatively earlier will be described. Matters not specifically mentioned may be considered to be the same as the embodiments described earlier or may be inferred from the embodiments described earlier. For convenience, the same reference numerals may be used for corresponding components between different embodiments, even if there are differences.

[0008] In the following description, when referring to a "rectangle" (or rectangular shape), a "square" (or square shape), and a "rectangle" (or rectangular shape), the corners may be chamfered by a curved surface or the like, as long as the concept of the shape described above is valid. For example, a corner formed by two sides may be chamfered to a length of 1 / 5, 1 / 10, or 1 / 20 of the length of the shorter of the two sides. It goes without saying that, when viewed microscopically, the corners may be rounded due to manufacturing precision (errors). The same applies to other polygons, etc.

[0009] (Outline of the embodiment) FIG. 1 is a perspective view showing a capacitor 1 (an example of a multilayer electronic component) according to a first embodiment. For convenience, a Cartesian coordinate system D1D2D3 is used in FIG. 1 and other figures described later. The capacitor 1 may be used with either side designated as the upper or lower side. However, in the description of the embodiments, for convenience, the +D3 side may be designated as the upper side, and terms such as upper surface and lower surface may be used.

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

[0011] Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1. Fig. 3 shows a D1D3 cross section taken through the external electrode 5 on the +D2 side. However, the D1D3 cross section taken through the external electrode 5 on the -D2 side, the D2D3 cross section taken through the external electrode 5 on the -D1 side, and the D2D3 cross section taken through the external electrode 5 on the +D1 side are basically the same. In explaining the embodiments, for convenience, the positional relationship between components may be explained using the terms D1, D2, and D3 without any particular mention, assuming the cross section shown in Fig. 3.

[0012] The main body 3 has, for example, an effective portion 11, two covers 13 respectively overlapping the upper and lower surfaces of the effective portion 11, and an underlayer 15 overlapping the surface of each cover 13 opposite the effective portion 11. The effective portion 11 has a plurality of dielectric layers 7 and a plurality of internal electrodes 9 that are alternately overlapped. The multiple internal electrodes 9 include a plurality of first internal electrodes 9A and a plurality of second internal electrodes 9B. Each underlayer 15 has, for example, four underlayer electrodes 16 at positions corresponding to the positions of the four external electrodes 5. The external electrodes 5 overlap the underlayer electrodes 16.

[0013] The active portion 11 directly functions as a capacitor. The cover 13 contributes, for example, to protecting and strengthening the main body portion 3. The base electrode 16 contributes, for example, to depositing a metal that will become the external electrode 5 by plating and / or improving the adhesive strength of the external electrode 5 to the main body portion 3.

[0014] The lower part of Figure 3 shows an enlarged view of the boundary between the base electrode 16 and the external electrode 5. The material of the base electrode 16 (e.g., a metal) diffuses into the external electrode 5, thereby forming an external diffusion layer 5a. The material of the external electrode 5 (e.g., a metal) diffuses into the base electrode 16, thereby forming an internal diffusion layer 16a. The external diffusion layer 5a and the base diffusion layer 16a form a diffusion layer 21. In other words, the base electrode 16 and the external electrode 5 share the diffusion layer 21, in which the material of the base electrode 16 and the material of the external electrode 5 are mixed together, and are thereby fixed to each other.

[0015] The diffusion layer 21 increases the adhesive strength of the external electrode 5 to the base electrode 16, thereby reducing the likelihood that the external electrode 5 will peel off from the main body 3. Note that, in order to form the diffusion layer 21, heating at an appropriate temperature or higher is required; simply depositing a film of a metal material on the base electrode 16 will not result in the formation of the diffusion layer 21.

[0016] The above-described effects do not necessarily have to be achieved. Furthermore, technical ideas from a different perspective than those described above may be extracted from the present disclosure. For example, technical ideas relating to the relative relationship between the lengths Li and Ld, which will be described later, may be extracted. In this case, for example, diffusion between the base electrode 16 and the external electrode 5 may not occur.

[0017] The above is an outline of the embodiment. Specifically, the embodiment will be roughly described in the following order. 1. Configuration of the capacitor according to the first embodiment (FIGS. 1 to 3) 1.1. Overall structure 1.2. Effective part 1.3.Cover 1.4. Base electrode 1.5.External electrode 2. Diffusion layer 2.1. Diffusion layer materials 2.2. Thickness of the diffusion layer 3. Capacitor manufacturing method 4. Configuration of Capacitor According to Another Embodiment 4.1. Second embodiment (FIG. 4) 4.2. Third embodiment (Fig. 6) 5. Working Example 6. Summary of embodiments

[0018] (1. Configuration of the Capacitor According to the First Embodiment) (1.1. Overall structure) 1 is configured as, for example, a surface-mounted chip component. Specifically, for example, the capacitor 1 is placed with its -D3 or +D3 side facing a circuit board (not shown). Then, the four pads on the circuit board are joined to the four external electrodes 5 with a conductive joining material (e.g., solder) (not shown), thereby mounting the capacitor on the circuit board.

[0019] The configuration (internal structure and external shape) of capacitor 1 is, for example, approximately plane-symmetric with respect to a plane of symmetry (not shown) that is parallel to the D1D2 plane and passes through the center of the thickness direction (D3 direction) of capacitor 1. Furthermore, the configuration of capacitor 1 is, for example, 180° rotationally symmetric when viewed in the D3 direction. Of course, capacitor 1 does not have to have such symmetry.

[0020] The shape of the main body 3 is, for example, roughly a thin rectangular parallelepiped. This rectangular parallelepiped may be square (as shown in the example) or rectangular (excluding squares; the same applies below) in plan view. For convenience, in the description of the embodiments, a square shape may be assumed unless otherwise specified.

[0021] The specific dimensions of the main body 3 (or capacitor 1) are arbitrary. To give an example of dimensions when the capacitor 1 is relatively small, the lengths of the main body 3 (or capacitor 1) in the D1 and D2 directions may each be 0.030 mm or more and 0.200 mm or less. When the length in the D1 direction is L and the length in the D2 direction is W, L / W may be 0.5 or more and 2.0 or less. The thickness in the D3 direction may be 0.030 mm or more and 0.200 mm or less. When the surface of the main body 3 is not flat, for example, the maximum values ​​of the various dimensions may be within the above ranges (the same applies hereinafter to the various dimensions of other components unless a contradiction arises).

[0022] Unless otherwise specified, the example dimensions of each component described below are for a relatively small capacitor 1. Therefore, dimensions larger (or smaller) than the illustrated dimensions may be used.

[0023] A plurality of components of the same type (e.g., 5, 7, 9, 13, 15, 16, 17, 19, or 20, etc.) may basically (except for relatively small differences, for example; the same applies below) be provided with the same (or corresponding) shape, size, material, position, etc. unless otherwise specified or unless a contradiction occurs. Therefore, unless otherwise specified or unless a contradiction occurs, the description of one component may be considered to be common to a plurality of components of the same type.

[0024] A layered (membrane-like) component (e.g., 5, 7, 9, 15, 17, or 19) may be entirely made of one material, but may also be made of stacked layers made of different materials.

[0025] (1.2. Effective part) The shape of the effective portion 11 shown in FIG. 3 is, for example, a generally thin rectangular parallelepiped. Its planar shape is basically the same as that of the main body portion 3. The specific thickness of the effective portion 11 is arbitrary. For example, the thickness of the effective portion 11 may be 30% or more, 40% or more, or 50% or more of the thickness of the main body portion 3, or 90% or less, 80% or less, or 70% or less. The above lower and upper limits may be combined arbitrarily. The thickness of the main body portion 3 is, for example, the thickness from the upper surface of the upper base electrode 16 to the lower surface of the lower base electrode 16. The thickness of the effective portion 11 is, for example, the thickness from the upper surface of the uppermost internal electrode 9 to the lower surface of the lowermost internal electrode 9.

[0026] The dielectric layer 7 is basically a layer having a constant thickness (at least between the internal electrodes 9). The thickness of the dielectric layer 7 may be appropriately set depending on the characteristics required of the capacitor 1. Examples of relatively thin thicknesses include a thickness between adjacent internal electrodes 9 (between the first internal electrode 9A and the second internal electrode 9B) of 0.1 μm or more or 0.5 μm or more, and a thickness of 3.0 μm or less, 2.0 μm or less, or 1.0 μm or less. The above upper and lower limits may be arbitrarily combined. The shape and dimensions of the dielectric layer 7 in a planar view are basically the same as those of the active portion 11 in a planar view. The material of the dielectric layer 7 is, for example, ceramics, and the specific type is also arbitrary. The number of laminated dielectric layers 7 (internal electrodes 9) is arbitrary. For example, the number is 10 to 30.

[0027] The internal electrodes 9 are layered and have a constant thickness. The thickness of the internal electrodes 9 is arbitrary, and may be thinner, the same as, or thicker than the thickness of the regions of the dielectric layer 7 between the internal electrodes 9. Examples of relatively thin thicknesses include the thickness of the internal electrodes 9 being 0.3 μm or more or 0.5 μm or more, and 3.0 μm or less, 2.0 μm or less, or 1.0 μm or less. The above lower and upper limits may be combined arbitrarily.

[0028] The material of the internal electrode 9 is, for example, a metal. The specific type of metal is arbitrary. For example, the entire or main component (e.g., 60% by mass or more of the metal (or the material of the internal electrode 9) is a base metal (e.g., Ni and / or Cu). The internal electrode 9 may contain ceramics in addition to the metal. This ceramic may be a common material (hereinafter, for convenience, the ceramic in the electrode will be referred to as the common material) when the internal electrode 9 is formed from a conductive paste that is co-fired with a ceramic green sheet that becomes the dielectric layer 7. The common material may be, for example, the same as the component (e.g., the main component) contained in the dielectric layer 7. As an example, the common material may be barium titanate. The content of the common material in the internal electrode 9 (after firing) is arbitrary, and may be, for example, 1% by mass or more and 30% by mass or less.

[0029] Fig. 2 is an exploded perspective view of the capacitor 1. Fig. 2 is a schematic view for understanding the shapes and relative positions of the internal electrodes 9, etc. Therefore, Fig. 2 shows a smaller number of various layers than Fig. 3.

[0030] The internal electrode 9 has, for example, a rectangular (square in the illustrated example) electrode body 9a in a plan view and a pair of lead electrodes 9b extending from a pair of opposing 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 11. 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 opposing corners of the main body portion 3.

[0031] The first internal electrode 9A and the second internal electrode 9B face each other with the dielectric layer 7 interposed therebetween. A pair of lead electrodes 9b of the first internal electrode 9A and a pair of lead electrodes 9b of the second internal electrode 9B are located on different diagonal lines in a planar perspective view. Both are connected to different pairs of external electrodes 5.

[0032] The electrode body 9a and the extraction electrode 9b may have any dimensions. For example, the length of the extraction electrode 9b on one side of the dielectric layer 7 (the length of one side of the edge) is approximately the same as the length of the external electrode 5 along the above-mentioned side.

[0033] (1.3. Cover) The cover 13 shown in FIG. 3 is, for example, a layer having a shape and dimensions that allow it to overlap the effective portion 11 without excess or deficiency. The thickness of the cover 13 is approximately constant in both the region where the base electrode 16 is disposed and the region where the base electrode 16 is not disposed. The ratio of the thickness of the cover 13 to the thickness of the main body portion 3 may be approximately the reverse of the ratio of the thickness of the effective portion 11 to the thickness of the main body portion 3 (as described above). For example, in an embodiment in which covers 13 are provided on both sides in the D3 direction, the thickness of one cover 13 may be, for example, 5% or more, 10% or more, or 15% or more of the thickness of the main body portion 3, or 35% or less, 30% or less, or 25% or less. The above lower and upper limits may be arbitrarily combined. The thickness of the cover 13 is, for example, the thickness in the region that overlaps the internal electrode 9 but does not overlap the base electrode 16 (i.e., the region that is not crushed by the base electrode 16).

[0034] Each cover 13 has, for example, a plurality of insulating layers 17 (two in the example of FIG. 3 ) and at least one dummy layer 19 (one in the example of FIG. 3 ) located between the plurality of insulating layers 17. Each dummy layer 19 has, for example, four dummy electrodes 20 at positions corresponding to the positions of the four external electrodes 5. The dummy electrodes 20 contribute to, for example, reinforcing the cover 13 and / or improving the connection strength between the main body 3 and the external electrodes 5, and also function as a base for the external electrodes 5 in an embodiment in which the external electrodes 5 are formed by plating. Unlike the example shown in the figure, the cover 13 may have only one or more insulating layers 17 (it may not have a dummy layer 19).

[0035] The insulating layers 17 and the dummy layers 19 are alternately stacked one on top of the other. In other words, dummy layers 19 are provided at the boundaries of all insulating layers 17. Unlike the illustrated example, dummy layers 19 may be provided only at some of the boundaries. For example, dummy layers 19 may not be provided at one or more boundaries relatively close to the effective portion 11, and dummy layers 19 may be provided only at one or more boundaries relatively far from the effective portion 11. In such a case, however, two or more insulating layers 17 that are in close contact with each other without a dummy layer 19 interposed therebetween may be regarded as a single insulating layer 17.

[0036] The insulating layer 17 is a layer having a substantially constant thickness, excluding variations in thickness resulting from the presence or absence of overlap with the conductor layers (9, 15, and 19). The planar shape of the insulating layer 17 is, for example, basically 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. Furthermore, the material of the insulating layer 17 may be, for example, ceramics or a material other than ceramics.

[0037] 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 refer to the thickness between conductor layers or the thickness of the region not overlapping a conductor layer; the same applies hereinafter in this paragraph). For example, the thickness of the insulating layer 17 may be two or more, three or more, or five or more times the thickness of the dielectric layer 7, and may be 20 or less, 10 or less, or 5 or less times the thickness of the dielectric layer 7. The above lower and upper limits may be combined arbitrarily. For example, the thickness of the insulating layer 17 may be 1.0 μm or more or 2.0 μm or more, and may be 10.0 μm or less or 5.0 μm or less. The above lower and upper limits may be combined arbitrarily. Note that the insulating layer overlapping the uppermost internal electrode 9 may be considered to be the insulating layer 17, not the dielectric layer 7, regardless of its material or thickness. The same applies to the insulating layer overlapping the lowermost internal electrode 9.

[0038] The dummy electrode 20 is, for example, a layer having a substantially constant thickness. The material of the dummy electrode 20 is, for example, a metal. The specific type of metal is arbitrary. For example, the entire or main component of the metal of the dummy electrode 20 (or the material of the dummy electrode 20) is a base metal (e.g., Ni and / or Cu). The dummy electrode 20 may also contain ceramics, similar to the internal electrode 9. The description of the ceramics in the internal electrode 9 may be applied to the ceramics in the dummy electrode 20 by replacing the terms internal electrode 9 and dielectric layer 7 with the terms dummy electrode 20 and insulating layer 17, respectively. The material of the dummy electrode 20 may be the same as or different from the material of the internal electrode 9.

[0039] In a plan view, the position, shape, and size of the dummy electrode 20 are arbitrary. In the examples of Figures 2 and 3, the position, shape, and size of the dummy electrode 20 are such that, in a planar perspective view, it overlaps approximately exactly with the external electrode 5 (however, the external electrode 5 is slightly wider). The dummy electrode 20 is exposed, for example, on the side surface of the main body 3. This exposed portion is fixed to the external electrode 5.

[0040] The thickness of the dummy electrode 20 is arbitrary. For example, the thickness of the dummy electrode 20 may be thicker than, equal to, or thinner than the thickness of the internal electrode 9 (as in the illustrated example). For example, the thickness of the dummy electrode 20 may be 1 time or more, 1.5 times or more, or 2 times or more, or 10 times or less, 5 times or less, or 2 times or less, of the thickness of the internal electrode 9. The above lower and upper limits may be combined arbitrarily. For example, the thickness of the dummy electrode 20 may be 0.3 μm or more, 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more, or 10.0 μm or less, 5.0 μm or less, 3.0 μm or less, or 2.0 μm or less. The above lower and upper limits may be combined arbitrarily. The thickness of the dummy electrode 20 may be thinner than, equal to, or thicker than the thickness of the insulating layer 17 (as in the illustrated example).

[0041] (1.4. Base electrode) The base electrode 16 is, for example, a layer having a substantially constant thickness. The material of the base electrode 16 is, for example, a metal. The specific type of metal is arbitrary. For example, the entire or main component of the metal of the base electrode 16 (or the material of the base electrode 16) is a base metal (e.g., Ni and / or Cu). The base electrode 16 may also contain ceramics, similar to the internal electrodes 9 and dummy electrodes 20. The description of the ceramics in the internal electrode 9 may be applied to the ceramics in the base electrode 16 by replacing the terms internal electrode 9 and dielectric layer 7 with the terms base electrode 16 and insulating layer 17, respectively. The material of the base electrode 16 may be the same as or different from the material of the internal electrodes 9 and / or dummy electrodes 20.

[0042] In a plan view, the position, shape, and size of the base electrode 16 are arbitrary. In the examples of Figures 2 and 3, the position, shape, and size of the base electrode 16 are set to a position, shape, and size that approximately overlaps with the external electrode 5 in a planar perspective view (however, the external electrode 5 is slightly wider).

[0043] The thickness of the base electrode 16 is arbitrary. For example, the thickness of the base electrode 16 may be thicker than, approximately the same as, or thinner than the thickness of the internal electrode 9 and / or the dummy electrode 20 (as in the illustrated example). For example, the thickness of the base electrode 16 may be two or more times, three or more times, or five or more times, or 20 or less times, ten or less times, or five or less times, the thickness of the internal electrode 9 and / or the dummy electrode 20. The above-mentioned lower and upper limits may be combined arbitrarily. For example, the thickness of the base electrode 16 may be 2.0 μm or more, 3.0 μm or more, or 5.0 μm or more, or 20.0 μm or less, 10.0 μm or less, or 5.0 μm or less. The above-mentioned lower and upper limits may be combined arbitrarily. The thickness of the base electrode 16 may be thinner, equal to, or thicker than the thickness of the insulating layer 17 (as in the illustrated example).

[0044] (1.5.External electrode) The external electrode 5 is, for example, in the form of a layer having a substantially constant thickness. The material of the external electrode 5 is, for example, a metal. The specific type of metal is arbitrary. For example, the metal of the external electrode 5 (or the material of the external electrode 5) is entirely or mainly a base metal (e.g., Ni and / or Cu). The external electrode 5 may or may not contain a non-metal (e.g., ceramics). In the description of the embodiments, the latter is basically taken as an example. Furthermore, the external electrode 5 may be formed by laminating different materials as necessary. For example, the external electrode 5 may be formed by laminating Cu, Ni, and Sn from the base electrode 16 side. The material of the external electrode 5, the material of the internal electrode 9, the material of the dummy electrode 20, and / or the material of the base electrode 16 may be the same as or different from the material of the external electrode 5. However, before diffusion bonding, the material of at least the layer of the external electrode 5 that is in contact with the base electrode 16 is different from the material of the layer of the base electrode 16 that is in contact with the external electrode 5.

[0045] As shown in FIG. 1 , the external electrodes 5 cover the four surfaces (top, bottom, and two side surfaces) of the main body 3, for example, roughly at the corners of the main body 3 in a plan view. This allows one external electrode 5 to be connected to one extraction electrode 9b on two side surfaces of the main body 3, and also makes it possible to surface mount the capacitor 1 on either the top or bottom surface. The shape and dimensions of the portions of the external electrodes 5 on each surface are arbitrary. The planar shape of the portion of the external electrode 5 located on the top or bottom surface of the main body 3 is, for example, rectangular (square in the illustrated example). The planar shape and dimensions of the portion of the external electrode 5 located on the side surface of the main body 3 are, for example, rectangular with the same horizontal length as the portion located on the top or bottom surface.

[0046] The thickness of the external electrode 5 is arbitrary. For example, the thickness of the external electrode 5 may be thicker than the thicknesses of the internal electrode 9, the dummy electrode 20, and the base electrode 16. For example, the thickness of the external electrode 5 may be 1.2 times or more, 2 times or more, or 3 times or more the thickness of the base electrode 16, or 10 times or less, 5 times or less, or 3 times or less. The above lower and upper limits may be combined arbitrarily. Furthermore, for example, the thickness of the external electrode 5 may be 3 μm or more, 5 μm or more, or 10 μm or more, or 30 μm or less, 20 μm or less, or 10 μm or less. The above lower and upper limits may be combined arbitrarily.

[0047] (2. Diffusion Layer) (2.1. Diffusion Layer Materials) The main component of the base electrode 16 (or a metal therein; the same applies hereinafter) will be referred to as the first metal. The main component of the external electrode 5 will be referred to as the second metal. The first metal and the second metal are different from each other. For convenience, unless otherwise specified, the first metal will be taken as an example of the material of the base electrode 16 that diffuses into the external electrode 5, and the second metal will be taken as an example of the material of the external electrode 5 that diffuses into the base electrode 16. In the following description, unless a contradiction occurs, the term "first metal" may be interchanged with the term "material of the base electrode 16," and the term "second metal" may be interchanged with the term "material of the external electrode 5."

[0048] Furthermore, in the following description, for convenience, unless otherwise specified, diffusion may be described focusing only on metals. For example, the mass percentages shown below may be interpreted as values ​​that ignore the common materials (metals and non-metals contained in the common materials) contained in the base electrode 16, unless a contradiction arises. However, unless a contradiction arises, the mass percentages may be interpreted as values ​​that take into account the common materials (or, from another perspective, all components of the base electrode 16). Also, exceptionally, the atomic percentages described below refer to all atoms contained in the base electrode 16 or the external electrode 5. For example, the denominator (or numerator) of the atomic percentage of the base electrode 16 includes the amount of elements contained in the common materials.

[0049] The portion of the base electrode 16 other than the base diffusion layer 16a is referred to as the base non-diffusion layer 16b. The portion of the external electrode 5 other than the outer diffusion layer 5a is referred to as the outer non-diffusion layer 5b. The boundary between the base electrode 16 and the external electrode 5 is referred to as the interface BS.

[0050] The base non-diffusion layer 16b does not necessarily have to be present. That is, the second metal of the external electrode 5 may diffuse throughout the entire thickness of the base electrode 16, so that the entire base electrode 16 becomes the base diffusion layer 16a. While the base non-diffusion layer 16b has been described above, the same applies to the external non-diffusion layer 5b.

[0051] Before the first metal of the base electrode 16 diffuses into the external electrode 5, the external diffusion layer 5a and the external non-diffusion layer 5b are a single metal layer made of the same material. Note that the external electrode 5 may be configured by stacking multiple metal layers before the above-mentioned diffusion. However, in the following description, for convenience, the above-mentioned single metal layer may be referred to as the external electrode 5 unless otherwise specified. While the description has been given for the external electrode 5, the same applies to the base electrode 16.

[0052] When another metal layer is present on the side of the external non-diffusion layer 5b opposite the base electrode 16, the material of the other metal layer may diffuse into the external non-diffusion layer 5b. For the sake of simplicity, the following description of such diffusion will be omitted. Note that, unless otherwise specified or unless a contradiction arises, the following description of the components of the external non-diffusion layer 5b may apply to aspects in which the above-mentioned diffusion has occurred and / or aspects in which it has not occurred. While the description has been given for the external electrode 5, the same applies to the base electrode 16.

[0053] As described above, a component that accounts for 60% by mass or more is referred to as the main component, and the main component of the base electrode 16 is referred to as the first metal. Which component accounts for 60% by mass or more may be determined, for example, based on the material of the base electrode 16 before diffusion occurs. When determining the main component of the base electrode 16 based on the base electrode 16 after diffusion, the determination may be made, for example, based on a region of the thickness of the base electrode 16 where the second metal has not diffused. As will be understood from the description below, this region may be, for example, a region of the base non-diffusion layer 16b that is further from the external electrode 5 than the base diffusion layer 16a.

[0054] In an embodiment in which the base electrode 16 does not have a region where the second metal has not diffused, it may be determined whether any component is present at 60 mass % or more in the region where the amount of diffusion of the second metal (e.g., atomic %) is the smallest (or the region expected to be such). The region where the second metal has not diffused can also be considered an example of the region where the amount of diffusion of the second metal is the smallest. In a situation in which the second metal is not specified, for example, the region farthest from the external electrode 5 (the central region of the thickness of the base electrode 16 depending on the configuration of the side opposite to the external electrode 5) may be used as the region where the amount of diffusion of the second metal is expected to be the smallest.

[0055] The main component of the base electrode 16 has been described above, but the same applies to the main component of the external electrode 5. Furthermore, in the following description, terms such as "base electrode 16 before diffusion" may be replaced with terms such as "a region of the base electrode 16 in which the amount of diffusion of the second metal is smallest" unless a contradiction arises. Similarly, terms such as "external electrode 5 before diffusion" may be replaced with terms such as "a region of the external electrode 5 in which the amount of diffusion of the first metal is smallest" unless a contradiction arises.

[0056] Specific embodiments of the diffusion layer 21 include, for example, the following first and second embodiments.

[0057] In the first embodiment, the base electrode 16 and the external electrode 5 before diffusion contain different pure metals. The elements of the pure metals are a first metal and a second metal. The diffusion layer 21 is an alloy of the first metal and the second metal. As a specific example, the first metal (base electrode 16) is Ni, the second metal (external electrode 5) is Cu, and the material of the diffusion layer 21 is a Ni-Cu alloy and / or a Cu-Ni alloy.

[0058] It goes without saying that even pure metals may contain unavoidable impurities. The impurities may be metals and / or non-metals. The amount of these impurities may be taken into consideration when determining whether the requirements for the main component, such as 60 mass % or the 12.5 atomic % described below, are met. Impurities in materials that are not pure metals are treated in the same way.

[0059] In the second embodiment, at least one of the base electrode 16 and the external electrode 5 before diffusion contains an alloy. However, the main components (first metal and second metal) of the material of the base electrode 16 and the material of the external electrode 5 are different from each other. The diffusion layer 21 is an alloy containing both main components. As a specific example, the base electrode 16 is made of a Ni alloy (the first metal is Ni), the external electrode 5 is made of a Cu alloy (the second metal is Cu), and the material of the diffusion layer 21 is a Ni-Cu alloy and / or a Cu-Ni alloy.

[0060] In the specific example of the second aspect, examples of the minor components (e.g., components of 40 mass % or less) contained in the Ni alloy (metal constituting the base electrode 16 before diffusion) include Cr, Mo, Fe, Co, and Cu. Examples of the minor components contained in the Cu alloy (metal constituting the external electrode 5 before diffusion) include Sn, Zn, Pb, Fe, Mn, Al, Be, W, and Ni.

[0061] As can be seen from the above example, in the second embodiment, the base electrode 16 (e.g., Ni alloy) before diffusion may contain, as a minor component, the main component (second metal: e.g., Cu) of the external electrode 5 before diffusion. However, when the definition of the diffusion layer 21 described below is adopted, the presence of the base diffusion layer 16a can be identified when the amount of the second metal contained as a minor component in the base electrode 16 before diffusion is less than 12.5 atomic %. While the minor components of the base electrode 16 have been described above, the same applies to the minor components of the external electrode 5.

[0062] In the above specific examples according to the second aspect, the main components (each of the first metal and the second metal) may contain, for example, one element and / or one element may be considered as the main component. However, as long as the first metal and the second metal do not contain the same elements, two or more elements may be considered as the main components and / or two or more elements may be considered as the main components. For example, consider an embodiment in which the base electrode 16 before diffusion is Ni (pure metal) and the external electrode 5 before diffusion is a Cu-Al alloy. In this case, the requirement of 60 mass % or more of Cu alone may be satisfied in the external electrode 5, or the requirement of 60 mass % or more of Cu and Al combined may be satisfied. In the former case, only Cu may be considered as the main component of the external electrode 5, or both Cu and Al may be considered as the main components.

[0063] The state of the alloy in the diffusion layer 21 is arbitrary. For example, the alloy may be primarily a solid solution, a eutectic, or an intermetallic compound. For example, a Ni-Cu alloy or a Cu-Ni alloy is usually a solid solution. Furthermore, in the diffusion layer 21, for example, grain boundary diffusion and / or volume diffusion may occur.

[0064] (2.2. Thickness of the diffusion layer) The thickness t1 of the base diffusion layer 16a and the thickness t2 of the outer diffusion layer 5a are arbitrary. For example, the thickness t1 may be 1.0 μm or more and 3.5 μm or less, and / or may be 0.25 to 0.88 times the thickness of the base electrode 16. The thickness t2 may be 1.0 μm or more and 3.5 μm or less, and / or may be 0.10 to 0.58 times the thickness of the outer electrode 5. Furthermore, the thicknesses t1 and t2 may be the same or different from each other. In the latter case, the degree of difference is also arbitrary. For example, the thickness t1 may be 2 / 3 to 3 / 2 or 6 / 7 to 7 / 6 of the thickness t2. Note that in the examples described below, it will be shown that a certain degree of adhesive strength of the outer electrode 5 is ensured when the thicknesses are as described above.

[0065] Here, in a region of the base electrode 16 that is relatively far from the external electrode 5, for example, the amount of diffusion of the main component (second metal) of the external electrode 5 gradually decreases with increasing distance from the external electrode 5. Therefore, the boundary line of the base diffusion layer 16a on the opposite side from the external electrode 5 (the boundary line between the base diffusion layer 16a and the base non-diffusion layer 16b) for determining the thickness t1 may be set to a position where the second metal is present at 12.5 atomic % or more. In other words, the base diffusion layer 16a may be set to a region containing 12.5 atomic % or more of the second metal. The same applies to the boundary line when determining the thickness t2. That is, the external diffusion layer 5a may be set to a region containing 12.5 atomic % or more of the main component (first metal) of the base electrode 16.

[0066] The value of 12.5 atomic % is the value used when determining thickness t1 and thickness t2 in the examples described below. Here, the diffusion layer is defined using the numerical value of 12.5 atomic % for the convenience of determining thickness t1 and / or thickness t2. However, if there is no need to determine thickness t1 and / or thickness t2, the diffusion layer does not need to be defined by such a definition. However, the above definition may be used as needed in situations other than when determining thickness t1 and / or thickness t2.

[0067] The boundary line between the underlying diffusion layer 16a and the underlying non-diffusion layer 16b may be determined with the precision required to determine the thickness of the diffusion layer 21. For example, since the range of thicknesses t1 and t2 exemplified in the present disclosure (described above) has a significant digit of 0.1 μm, the boundary line may be determined with a precision of 0.1 μm (or even higher precision). Furthermore, the atomic percentage may be calculated, for example, in a unit area that allows the boundary line to be determined with the above-described precision. For example, when the boundary line is determined with a precision of 0.1 μm, the above-described unit area may be, for example, 0.01 μm. 2 (or an area even smaller). The shape of each unit area may be, for example, a square (for example, a square of 0.1 μm×0.1 μm).

[0068] The boundary line where the diffusion amount is 12.5 atomic % is not necessarily linear, but may have undulations (wave-like). In cases where undulations affect the determination of whether thicknesses t1 and / or t2 are within the ranges exemplified in the embodiments, thicknesses t1 and t2 may be determined based on, for example, the average height of the boundary line. In the examples described below, the average height is also used.

[0069] In the example of FIGS. 1 to 3, the base electrodes 16 are located at the four corners of each of the upper and lower surfaces of the main body 3, and a total of eight base electrodes 16 are provided. The above-described range of thickness t1 and / or thickness t2 does not need to be satisfied for all of the multiple (eight) base electrodes 16. For example, the above-described thickness range may be satisfied for only one base electrode 16. Of course, the above-described thickness range may be satisfied for all of the base electrodes 16.

[0070] When focusing on each base electrode 16, the above thickness range does not have to be satisfied over the entire base electrode 16. For example, it may be satisfied over 50% or more or 80% or more of the area of ​​the base electrode 16. Of course, the above thickness range may be satisfied over the entire base electrode 16. However, even in this case, the unique portion may be excluded. An example of the unique portion is the edge of the base electrode 16. Since not only the top surface but also the side surface of the edge is covered by the external electrode 5, the diffusion layer 21 is basically formed over the entire thickness.

[0071] Whether or not the thickness range exemplified in the embodiment is satisfied in a certain area or more of each base electrode 16 may be determined based on, for example, a predetermined number (e.g., 3, 5, or 10) of D1D3 cross-sectional images set at equal distances along the length of the base electrode 16 in the D2 direction. If it is difficult to extract multiple cross-sectional images from one capacitor 1, multiple cross-sectional images may be extracted from multiple capacitors 1 of the same type.

[0072] The cross-sectional image may be obtained at an appropriate magnification using, for example, a scanning electron microscope (SEM). The SEM may have a function for displaying regions in the image in different colors according to the atomic percentage of a specific element. This function may be used to identify and measure the dimensions of regions where the first metal or the second metal is 12.5 atomic % or more.

[0073] Even when the material of the base electrode 16 and the material of the external electrode 5 are mixed, the interface BS can be observed in the SEM image. This can be due to the presence of a cavity between the two and / or different sizes of the crystal grains of the two. The interface BS, like the 12.5% ​​atomic boundary, can be identified with the accuracy required to calculate (determine) the thickness t1 and / or the thickness t2, and the average height can be identified as needed. Of course, if the thickness t1 and / or t2 is not measured, the interface BS does not necessarily have to be observable.

[0074] (3. Capacitor manufacturing method The capacitor 1 may be manufactured by various methods. For example, the general procedure may be the same as a known procedure. An example is shown below.

[0075] First, ceramic green sheets that will become the dielectric layers 7 and insulating layers 17 are prepared. Next, a conductive paste that will become the internal electrodes 9, dummy electrodes 20, or base electrodes 16 is applied (e.g., printed) to the ceramic green sheets. Next, the ceramic green sheets are stacked to prepare a laminate that will become the main body portion 3. Note that the stacking of the laminate that will become the effective portion 11 and the stacking of the portion that will become the cover 13 on the laminate may be performed together or separately.

[0076] The steps up to the production of the laminate are carried out, for example, on a mother substrate the size of which will be used to produce a large number of main body portions 3. After the laminate is produced, the mother substrate including the laminate is diced (e.g., cut) into pieces having a size roughly corresponding to the size of the main body portions 3. Next, the laminate having the size of the main body portions 3 is fired. After that, a metal film is formed on the main body portions 3, and external electrodes 5 are formed.

[0077] Degreasing may be performed before firing. Firing may be performed, for example, in a reducing atmosphere. Re-oxidation 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.

[0078] The external electrode 5 may be formed by various methods. For example, metal may be deposited on the surface of the base electrode 16 and the edge of the internal electrode 9 by electroless plating and / or electrolytic plating. Alternatively, a thin film formation method such as a dipping method, a printing method, CVD (Chemical Vapor Deposition), or PVD (Physical Vapor Deposition) may be employed. As understood from the above, the base electrode 16 may or may not contribute to the deposition of metal.

[0079] To form the diffusion layer 21, the external electrode 5 and the base electrode 16 are heated while being pressurized. Any specific method can be used. For example, a heater may be pressed against the external electrode 5, or the capacitor 1 may be placed in a furnace together with a tool that presses the external electrode 5 against the base electrode 16. The process for forming the diffusion layer 21 may also serve as another process (for example, an annealing process).

[0080] The heating temperature may be set appropriately depending on the specific types of the first metal and the second metal. For example, in the case of Ni and Cu, heating may be performed so that the temperature reaches 450°C or higher or 600°C or higher. However, the temperature at this time is, for example, below the solidus. The specific magnitude of the pressure is also arbitrary. The thickness of the diffusion layer 21 can be adjusted by controlling, for example, the heating temperature, heating time, and number of heating cycles.

[0081] (4. Configuration of Capacitor According to Other Embodiments) (4.1. Second embodiment, etc.) 4 is a perspective view of a capacitor 201 according to the second embodiment. FIG. 3 according to the first embodiment may be referred to as a cross-sectional view of the capacitor 201.

[0082] Generally speaking, capacitor 201 is a two-terminal type, which differs from capacitor 1, which is a four-terminal type. Capacitor 201 may also have diffusion layer 21, as described with reference to FIG.

[0083] The specific shapes and dimensions of each part of capacitor 201 may differ from those of capacitor 1, since it is a two-terminal type. Specifically, they are as follows.

[0084] The main body 203 (or the capacitor 201) has a shape of, for example, a roughly rectangular parallelepiped. For example, the height (length in the D3 direction) of this rectangular parallelepiped may be equal to (as in the illustrated example) or smaller than the width (length in the D2 direction). The length (D1 direction) of the rectangular parallelepiped is, for example, greater than the width. The dimensions of the main body 203 are arbitrary. As long as the length in the D1 direction is greater than the length in the D2 direction, the specific examples of the dimensions of the main body 3 in the first embodiment may be applied to the dimensions of the main body 203. The external electrode 5 is generally layered, covering the longitudinal ends of the main body 203 over five faces of the rectangular parallelepiped.

[0085] The planar shape of the internal electrode 9 is, for example, approximately a rectangle having four sides parallel to the four sides of the rectangular main body 203 (dielectric layer 7). Of the four sides of the internal electrode 9, two long sides and one short side are, for example, located inside the side surface of the main body 203 (not exposed). The remaining short side is exposed from the side surface of the main body 203 on the +D1 side or the -D1 side. The region of the internal electrode 9 that overlaps with other internal electrodes 9 in a planar perspective view is the electrode main body 9a. The portion extending from the electrode main body 9a to the external electrode 5 is the extraction electrode 9b.

[0086] Each dummy layer 19 has, for example, two dummy electrodes 20 at both ends in the longitudinal direction of the main body portion 203. The planar shape of the dummy electrode 20 is, for example, a rectangular shape spanning the entire width (length in the D2 direction) of the main body portion 203, and is exposed, for example, from the side surface on the +D1 side or the -D1 side of the main body portion 203 and from the side surface on the +D2 side and the -D2 side. The above description of the configuration of the dummy layer 19 (dummy electrode 20) in a planar view may be applied to the configuration of the base layer 15 (base electrode 16) in a planar view.

[0087] Although not specifically shown, another example of the capacitor configuration will be given below.

[0088] The capacitor may have an exterior resin covering the entire structure illustrated in Fig. 1 or 4, and lead wires connected to the external electrodes 5 and extending from the exterior resin. From another perspective, the capacitor may be a through-hole mount type rather than a surface mount type. In such a configuration, one external electrode 5 may cover only one side surface.

[0089] Two types of internal electrodes 9 connected to different external electrodes 5 may be alternately stacked two by two, rather than one by one. In this case, for example, the thickness of the dielectric layer 7 between the internal electrodes 9 connected to the same external electrode 5 and facing each other may be thinner than the thickness of the dielectric layer 7 between the internal electrodes 9 connected to different external electrodes 5 and facing each other. As can be understood from this, the multiple dielectric layers 7 do not need to have the same shape and size.

[0090] Furthermore, two types of internal electrodes 9 connected to different external electrodes 5 do not have to face each other. For example, two types of internal electrodes 9 connected to different external electrodes 5 may be provided in the same layer, and an internal electrode 9 facing the two types of internal electrodes 9 may be provided, thereby forming a circuit in which two parallel plate capacitors are connected in series. Also, a circuit in which three or more parallel plate capacitors are connected in series may be formed.

[0091] In the example of FIG. 4 , the edge of the internal electrode 9, for example, a portion other than the -D1 side or the +D1 side (referred to as the "non-exposed edge portion" in this paragraph) is not exposed from the side surface of the main body portion 203. This non-exposed edge portion is covered by the portions of the dielectric layer 7 and the insulating layer 17 that extend outward beyond the non-exposed edge portion. However, the non-exposed edge portion may be covered by overlapping another dielectric layer on the side surface of the laminate formed by the dielectric layer 7 and the insulating layer 17, thereby preventing it from being exposed. From another perspective, the main body portion 203 does not need to have a laminated structure in its entirety.

[0092] (4.2. Third embodiment) FIG. 6 is a schematic cross-sectional view showing a part of a capacitor 301 according to the third embodiment, which corresponds to region VI in FIG.

[0093] In the capacitor 301, diffusion also occurs between the internal electrode 9 and the external electrode 5. Diffusion also occurs between the dummy electrode 20 and the external electrode 5. Note that only one of the former diffusion and the latter diffusion may occur. The third embodiment may be applied to any of the embodiments described so far. The above-described explanation regarding the diffusion between the base electrode 16 and the external electrode 5 (such as in Section 2) may be applied to the diffusion related to the internal electrode 9 and the diffusion related to the dummy electrode 20, for example, by replacing the term base electrode 16 with the term internal electrode 9 or dummy electrode 20, unless a contradiction or the like arises.

[0094] Specifically, as already described, the extraction electrode 9b of the internal electrode 9 (in other words, the edge of the internal electrode 9) and the inner surface of the external electrode 5 are in contact with each other. The internal electrode 9 and the external electrode 5 are fixed to each other via a shared diffusion portion in which the materials of both electrodes are mixed. In a planar perspective view, this diffusion portion extends along the edge of the internal electrode 9. In FIG. 6 , only the internal diffusion portion 9c, which is formed by the material of the external electrode 5 diffusing into the material of the internal electrode 9, is shown. In other words, the external diffusion portion, which is formed by the material of the internal electrode 9 diffusing into the material of the external electrode 5, is not shown. Note that the area in contact with the internal electrode 9 is small relative to the external electrode 5. Therefore, the external diffusion portion does not need to actually be formed, or it may be so small that it is difficult to observe.

[0095] The above explanation may be applied to the diffusion between the dummy electrode 20 and the external electrode 5 by replacing the term internal electrode 9 with the term dummy electrode 20 and the term internal diffusion portion 9c with the term dummy diffusion portion 20c, unless a contradiction arises.

[0096] The materials of the internal electrode 9, the dummy electrode 20, and the base electrode 16 may be the same as each other or different from each other as described above. This also applies when diffusion occurs between the internal electrode 9 and the external electrode 5 and / or between the dummy electrode 20 and the external electrode 5. For example, the internal electrode 9, the dummy electrode 20, and the base electrode 16 may be made of Ni or an alloy mainly composed of Ni, and the external electrode 5 may be made of Cu or an alloy mainly composed of Cu.

[0097] The length Li of the internal diffusion part 9c from the edge of the internal electrode 9 (in another aspect, the width of the internal diffusion part 9c extending along the edge of the internal electrode 9 in a plan view) is arbitrary. Similarly, the length Ld of the dummy diffusion part 20c from the edge of the dummy electrode 20 (in another aspect, the width of the dummy diffusion part 20c extending along the edge of the dummy electrode 20 in a plan view) is arbitrary. For example, at least one of Li < t1, t1 < Ld, and Li < Ld may hold, or all of them may not hold. For example, Li < t1 < Ld may hold (illustrated example).

[0098] The specific dimensions of Li, Ld, and t1 when the above relative relationship holds are also arbitrary. For example, an example where Li < t1 < Ld (or a part thereof) holds is given. t1 may be 1.05 or more, 1.10 or more, or 1.50 or more of Li, and may be 7.00 or less, 6.00 or less, or 5.00 or less. The above lower and upper limits may be combined with any of each other. Ld may be 1.05 or more, 1.10 or more, or 1.50 or more of t1, and may be 5.00 or less, 3.00 or less, or 2.00 or less. The above lower and upper limits may be combined with any of each other. Ld may be 1.10 or more, 1.20 or more, or 1.50 or more of Li, and may be 12.00 or less, 10.00 or less, or 5.00 or less. The above lower and upper limits may be combined with any of each other. t1 may be 0.30 μm or more and 6.00 μm or less. Li may be 0.20 μm or more and 5.90 μm or less (however, Li < t1). Ld may be 1.00 μm or more and 7.00 μm or less (however, Ld > Li and / or Ld > t1). The difference between Li and t1 may be 0.10 μm or more or 0.30 μm or more. The difference between t1 and Ld may be 0.10 μm or more or 0.30 μm or more. The difference between Li and Ld may be 0.20 μm or more or 0.4 μm or more.

[0099] The above relative relationship and / or conditions such as dimensions may hold only for one external electrode 5, or may hold for two or more (for example, all or more than 50%) of the external electrodes 5. Also, when focusing on each external electrode 5, the above conditions may hold only for one base electrode 16, one internal electrode 9, and / or one dummy electrode 20 joined to the one external electrode 5, or may hold for two or more (for example, all or more than 50%) of each electrode (16, 9, or 20). In the latter case, the actual values of each electrode may satisfy the above conditions, or the average value may satisfy the above conditions.

[0100] For example, when comparing the thickness t1 of one base electrode 16 with the length Li of the internal electrodes 9 connected to the same external electrode 5 as the base electrode 16, the average value of the lengths Li of 10 or more internal electrodes 9 and / or 30% or more (or 60% or more) of the total number of internal electrodes 9 may be used. Similarly, when comparing the thickness t1 (or the average value of the lengths Li) of one base electrode 16 with the length Ld of dummy electrodes 20 connected to the same external electrode 5 as the base electrode 16, the average value of the lengths Ld of two or more dummy electrodes 20 (however, if only one dummy electrode 20 is provided, one dummy electrode 20) and / or 30% or more (or 60% or more) of the total number of dummy electrodes 20 may be compared with the thickness t1 (or the average value of the lengths Li).

[0101] The above-described conditions regarding the relative relationships and / or dimensions of Li, t1, and Ld do not have to be satisfied over the entire length of the edge portion (contacting the external electrode 5) of the internal electrode 9 and / or dummy electrode 20. For example, the conditions may be satisfied only over 50% or 80% of the length of a specific edge portion (one or two sides) of the internal electrode 9 (or dummy electrode 20) that contacts the external electrode 5. Whether or not the above conditions are satisfied over a certain length or longer may be determined, for example, based on images of a predetermined number (e.g., 3, 5, or 10) of cross sections (e.g., D1-D3 cross sections) set at equal distances from the edge portion. If it is difficult to extract images of multiple cross sections from one capacitor 1, images of multiple cross sections may be extracted from multiple capacitors 1 of the same type.

[0102] The length Li may be obtained from an image showing a cross section such as that shown in FIG. 6 obtained by SEM or the like. The cross section may be, for example, a cross section (e.g., a D1D3 cross section) along a direction (cutting direction, e.g., D1 direction) perpendicular to an edge portion (e.g., extending in the D2 direction and contacting the external electrode 5) of the internal electrode 9 in a plan view, or may be a cross section appropriately separated from an edge portion (unique portion) of the internal electrode 9 along the cutting direction (e.g., a cross section crossing the center position of the edge portion extending in the D2 direction). Then, similar to the thickness t1, a range in which the main component (second metal) of the external electrode 5 is 12.5 atomic % or more may be identified as the internal diffusion region 9c, and the length Li may be measured. If the length Li varies in the thickness direction of the internal electrode 9, for example, the maximum value may be used for comparison with the thickness t1, etc.

[0103] The above description may be applied to the length Ld by replacing the terms "internal electrode 9," "internal diffusion portion 9c," and "length Li" with the terms "dummy electrode 20," "dummy diffusion portion 20c," and "length Ld," respectively. When determining whether the above-described conditions regarding the relative relationship and / or dimensions of Li, t1, and Ld are satisfied, Li, t1, and Ld may be taken to be values ​​obtained from the same multiple cross-sectional images (or a single cross-sectional image, depending on the circumstances). In this case, comparison may be performed for each cross-section to determine whether the above-described conditions are satisfied for multiple cross-sections (e.g., 60% or more), or average values ​​of each dimension (Li, t1, or Ld) for multiple cross-sections may be compared to determine whether the above-described conditions are satisfied. The thickness t1 measured for each cross-section and compared with Li and / or Ld may be an average value excluding unusual portions (e.g., edges). Taking the D1D3 cross section as an example, the average value of the thickness t1 may be the average value over a length of 30% or more, 50% or more, or 80% or more of the entire length of the base electrode 16 in the D1 direction.

[0104] The manufacturing method for realizing the above conditions related to the relative relationship and / or dimensions of Li, t1, and Ld is arbitrary. For example, in the manufacturing method described in the first embodiment, the above conditions may be realized by adjusting the particle size of metal particles (e.g., Ni particles) contained in the conductive paste that becomes the base electrode 16, the internal electrode 9, and / or the dummy electrode 20. The larger the particle size of the metal particles contained in each electrode (16, 9, or 20), the easier the material (e.g., Cu) of the external electrode 5 diffuses into the former electrode. Considering the temperature of each electrode in the heat treatment, etc., by adjusting the particle size, arbitrary Li, t1, and Ld can be realized. For example, in the applicant's prototype, the above conditions were realized by setting the particle size of Ni particles contained in the conductive paste that becomes the internal electrode 9, the base electrode 16, and the dummy electrode 20 to 150 nm to 200 nm, 350 nm to 400 nm, and 350 nm to 400 nm, respectively.

[0105] (5. Examples) A capacitor 1 according to an embodiment was prototyped, and the adhesion of the external electrode 5 was evaluated. As a result, it was confirmed that a capacitor 1 with a large adhesion of the external electrode 5 can be obtained by the diffusion layer 21. Specifically, it is as follows.

[0106] FIG. 5 is a chart showing the specifications of the capacitor 1 according to the example.

[0107] In this figure, "No." indicates the type of capacitor according to the example. In Examples E1 to E7, the configurations (thickness t1 and / or thickness t2) related to the diffusion layer 21 are different from each other.

[0108] The columns of "t1 (μm)" and "t2 (μm)" show the values of the thicknesses t1 and t2 in each example. In Examples E1 to E7, each of the thicknesses t1 and t2 is set within the range of 0.9 μm to 3.5 μm. In Examples E1, E6, and E7, t1 = t2. In Examples E2 and E4, t1 < t2. In Examples E3 and E5, t1 > t2.

[0109] The "Qual." column shows the evaluation results of the quality of the capacitor 1 according to the example. Specifically, for each of Examples E1 to E7, 100 samples were produced and examined for the presence or absence of peeling of the external electrode 5 from the base electrode 16. In the above column, the number of samples in which peeling occurred is shown as the numerator of a fraction.

[0110] The material of the base electrode 16 was Ni. The material of the external electrode 5 was Cu. The thickness of the base electrode 16 was set to a value in the range of 2 μm to 4 μm (design value: 3 μm). The thickness of the external electrode 5 was set to a value in the range of 2 μm to 10 μm (design value: 6 μm). Measurement of the thicknesses t1 and t2 was performed based on images obtained by SEM, as described above.

[0111] 5, peeling occurred in two samples in Example E7, which had the thinnest thicknesses t1 and t2, but peeling did not occur in any of the 100 samples in Examples E1 to E6. Although no samples without the diffusion layer 21 were produced, it can be inferred from the above results that the formation of the diffusion layer 21 reduces the likelihood of the external electrode 5 peeling off.

[0112] In Example E7, where peeling occurred, the thicknesses t1 and t2 were each 0.9 μm. In Examples E1 to E6, where peeling did not occur, the thicknesses t1 and t2 were each 1.0 μm or more. Therefore, it can be seen that by making the thicknesses t1 and t2 each 1.0 μm or more, a certain level of adhesive strength can be obtained.

[0113] The minimum value (1.0 μm) of thickness t1 in Examples E1 to E6, divided by an appropriate value (e.g., 2.0 μm, 3.0 μm, or 4.0 μm) selected from the range of thicknesses of the base electrode 16 of the samples, is normalized to 0.50, 0.33, or 0.25 (rounded to the nearest hundredth; the same applies below). The maximum value (3.5 μm) of thickness t1 in Examples E1 to E6, divided by an appropriate value (e.g., 3.5 μm or 4.0 μm) selected from the range of thicknesses of the base electrode 16 of the samples, is normalized to 1.00 or 0.88. The range of thickness t1 may be defined by the lower and / or upper limits determined in this manner. An example of this has already been described.

[0114] The minimum value of thickness t2 (1.0 μm) in Examples E1 to E6, divided by an appropriate value (e.g., 2.0 μm, 6.0 μm, or 10.0 μm) selected from the range of thicknesses of the external electrode 5 of the samples and normalized to 0.50, 0.17, or 0.10, respectively. The maximum value of thickness t2 (3.5 μm) in Examples E1 to E6, divided by an appropriate value (e.g., 3.5 μm, 6 μm, or 10 μm) selected from the range of thicknesses of the base electrode 16 of the samples and normalized to 1.00, 0.58, or 0.35, respectively. The range of thickness t2 may be defined by the lower and / or upper limits determined in this manner. An example of this has already been described.

[0115] (6. Summary of embodiments) In the following description, for convenience, the reference numerals of one of the embodiments will be used. However, the matters described below also apply to other embodiments unless a contradiction arises. In addition, the effects exemplified below may not be achieved.

[0116] The multilayer electronic component (capacitor 1) has an active portion 11, a cover 13, a base electrode 16, and an external electrode 5. The active portion 11 has dielectric layers 7 and internal electrodes 9 alternately stacked in the stacking direction (D3 direction). The cover 13 on the +D3 side overlaps the active portion 11 from the +D3 side of a first side (e.g., the +D3 side) and a second side (e.g., the -D3 side) in the D3 direction. The base electrode 16 on the +D3 side overlaps the cover 13 from the +D3 side. The external electrode 5 on the +D3 side overlaps the base electrode 16 on the +D3 side from the +D3 side. The base electrode 16 and the external electrode 5 may be fixed by sharing a diffusion layer 21 in which the material of the base electrode 16 and the material of the external electrode 5 are mixed.

[0117] Therefore, for example, as described in the overview of the embodiment, it is possible to increase the adhesive strength of the external electrode 5 to the base electrode 16. As a result, for example, the probability of producing defective products in which the external electrode 5 is peeled off from the base electrode 16 is reduced, and productivity is improved.

[0118] The edge of the internal electrode 9 may be in contact with the external electrode 5. The thickness t1 of the portion of the base electrode 16 where the material of the external electrode 5 is diffused at 12.5 atomic % or more may be greater than the length Li from the edge of the internal electrode 9 to the portion (internal diffusion portion 9c) where the material of the external electrode 5 is diffused at 12.5 atomic % or more into the internal electrode 9.

[0119] In this case, for example, the relatively large thickness t1 improves the effect of increasing the fixing strength. On the other hand, the relatively short length Li reduces the possibility of the internal electrode 9 expanding due to diffusion. As a result, for example, the possibility of peeling between the internal electrode 9 and the dielectric layer 7 is reduced. Furthermore, for example, the possibility of the characteristics of the capacitor 301 deteriorating due to the expansion (and even peeling) of the internal electrode 9 is reduced.

[0120] The cover 13 may have two or more insulating layers 17 stacked in the D3 direction, and a dummy electrode 20 located at the boundary between the two or more insulating layers 17. The edge of the dummy electrode 20 may be in contact with the external electrode 5. A thickness t1 of the portion of the external electrode 5 where the material of the external electrode 5 has diffused into the base electrode 16 at 12.5 atomic % or more may be smaller than a length Ld from the edge of the dummy electrode 20 to a portion (dummy diffusion portion 20c) where the material of the external electrode 5 has diffused into the dummy electrode 20 at 12.5 atomic % or more.

[0121] In this case, for example, the relatively long length Ld can increase the adhesive strength between the dummy electrode 20 and the external electrode 5. Unlike the internal electrode 9, the dummy electrode 20 does not directly affect the characteristics of the capacitor 1. Therefore, increasing the length Ld is unlikely to degrade the characteristics of the capacitor 1, unlike increasing the length Li. Furthermore, the contact area between the dummy electrode 20 and the external electrode 5 is usually smaller than the contact area between the base electrode 16 and the external electrode 5. Therefore, by making Ld>t1, it is easy to improve the overall adhesive strength of the external electrode 5 to the cover 13.

[0122] The edge (first edge) of the internal electrode 9 may be in contact with the external electrode 5, and the edge (second edge) of the dummy electrode 20 may be in contact with the external electrode 5. The length Li may be shorter than the length Ld.

[0123] In this case, as can be understood from the above description, it is possible to increase the adhesive strength between the dummy electrode 20 and the external electrode 5. On the other hand, the probability of expansion (and even peeling) of the internal electrode 9 due to diffusion is reduced.

[0124] The thickness t1 of the portion of the base electrode 16 where the material of the external electrode 5 (and / or the second metal) is diffused at 12.5 atomic % or more may be 1.0 μm or more and 3.5 μm or less. From another perspective, the thickness t1 may be 0.25 to 0.88 with respect to the thickness of the base electrode 16.

[0125] In this case, for example, by setting the thickness t1 to 1.0 μm or more and / or 0.25 μm or more, the adhesive strength of the external electrode 5 to the base electrode 16 can be maintained at a certain level or higher, as explained in the examples. If the thickness t1 is too large, the volume of the base diffusion layer 16a generally increases, although this depends on the types of the first metal and second metal. As a result, stress is generated between the base diffusion layer 16a and other layers (e.g., the insulating layer 17 and / or the base non-diffusion layer 16b), causing cracks. By setting the thickness t1 to 3.5 μm or less and / or 0.88 μm or less, for example, the likelihood of the above-mentioned cracks occurring can be reduced.

[0126] The thickness t2 of the portion of the base electrode 16 where the material (and / or the first metal) is diffused into the external electrode 5 at 12.5 atomic % or more may be 1.0 μm or more and 3.5 μm or less. From another perspective, the thickness t2 may be 0.10 to 0.58 times the thickness of the external electrode 5.

[0127] In this case, for example, by setting the thickness t2 to 1.0 μm or more and / or 0.10 μm or more, the adhesive strength of the external electrode 5 to the base electrode 16 can be maintained at a certain level or higher, as explained in the examples. When diffusion bonding is performed, voids are generated, depending on the conditions. If the thickness t2 is too large, the proportion of the total volume of the voids to the volume of the external electrode 5 increases. As a result, for example, the electrical resistivity of the external electrode 5 increases, and the electrical characteristics of the capacitor 1 deteriorate. For example, by setting the thickness t2 to 3.5 μm or less and / or 0.58 μm or less, the deterioration of the electrical characteristics as described above can be reduced.

[0128] The thickness t2 may be 2 / 3 or more and 3 / 2 or less of the thickness t1. In other words, the thickness t1 may be 2 / 3 or more and 3 / 2 or less of the thickness t2.

[0129] In this case, for example, the diffusion layer 21 is biased toward one of the base electrode 16 and the external electrode 5, which reduces the likelihood that the thickness t1 or the thickness t2 will be greater than the total thickness (t1+t2) of the diffusion layer 21. This in turn reduces the likelihood that the above-mentioned inconveniences will occur due to the thickness t1 or the thickness t2 being too thick. From another perspective, the thickness of the diffusion layer 21 can be increased while reducing the likelihood that the thickness t1 or the thickness t2 will be too thick, thereby increasing the adhesive strength.

[0130] The base electrode 16 may be mainly composed of a first metal at least in a region away from the external electrode 5. The external electrode 5 may be mainly composed of a second metal different from the first metal at least in a region away from the base electrode 16. In the diffusion layer 21, the first metal may be diffused into the external electrode 5, and the second metal may be diffused into the base electrode 16. The diffusion layer 21 has a thickness of 0.01 μm in a cross section parallel to the D3 direction. 2 The first metal may be contained in an amount of 12.5 atomic % or more per area of ​​the first metal.

[0131] In this case, for example, a certain degree of diffusion occurs, so the above-mentioned effects are more effectively achieved.

[0132] The technology according to the present disclosure is not limited to the above-described embodiments and may be implemented in various forms.

[0133] For example, the multilayer electronic component is not limited to a capacitor. For example, in a multilayer electronic component, some of the multiple internal electrodes may form a capacitor, and the other multiple internal electrodes may form an inductor or resistor. The multilayer electronic component may also form an appropriate circuit (e.g., a resonant circuit) as a whole. Furthermore, the cover, base electrode, and external electrode may be provided on only one of the upper and lower surfaces of the active part.

[0134] The external electrode 5 does not have to be in contact with the internal electrode 9 and / or the dummy electrode 20. For example, the base electrode 16 may cover the end face of the cover 13 and be in contact with the dummy electrode 20, or may cover the end face of the effective portion 11 and be in contact with the internal electrode 9.

[0135] The following inventions may be extracted from this disclosure. (1) an effective portion having dielectric layers and internal electrodes alternately stacked in a stacking direction; a cover overlapping the effective portion from the first side of a first side and a second side in the stacking direction; a base electrode overlapping the cover from the first side; an external electrode overlapping the base electrode from the first side; It has The base electrode and the external electrode are fixed by sharing a diffusion layer in which the material of the base electrode and the material of the external electrode are mixed. Multilayer electronic components. (2) The edges of the internal electrodes are in contact with the external electrodes, The thickness of the portion of the external electrode material that is diffused into the base electrode at 12.5 atomic % or more is greater than the length from the edge of the portion of the external electrode material that is diffused into the internal electrode at 12.5 atomic % or more. The multilayer electronic component according to (1). (3) The cover is Two or more insulating layers stacked in the stacking direction; a dummy electrode located at the boundary of the two or more insulating layers, an edge of the dummy electrode and the external electrode are in contact with each other; The thickness of the portion of the external electrode material that is diffused into the base electrode at 12.5 atomic % or more is smaller than the length from the edge of the portion of the external electrode material that is diffused into the dummy electrode at 12.5 atomic % or more. The multilayer electronic component according to (1) or (2). (4) The cover is Two or more insulating layers stacked in the stacking direction; a dummy electrode located at the boundary of the two or more insulating layers, a first edge of the internal electrode and the external electrode are in contact with each other; a second edge of the dummy electrode contacts the external electrode; The length from the first edge of a portion where the material of the external electrode is diffused into the internal electrode at 12.5 atomic % or more is shorter than the length from the second edge of a portion where the material of the external electrode is diffused into the dummy electrode at 12.5 atomic % or more. The multilayer electronic component according to any one of (1) to (3). (5) The material of the external electrode is 12.5 atomic % or more and diffused into the base electrode to a thickness of 1.0 μm or more and 3.5 μm or less. The multilayer electronic component according to any one of (1) to (4). (6) The material of the base electrode is 12.5 atomic % or more and diffused into the external electrode to a thickness of 1.0 μm or more and 3.5 μm or less. The multilayer electronic component according to any one of (1) to (5). (7) The thickness of the external electrode material diffused into the base electrode at 12.5 atomic % or more is 0.25 to 0.88 times the thickness of the base electrode. The multilayer electronic component according to any one of (1) to (6). (8) The thickness of the material of the base electrode diffused into the external electrode at 12.5 atomic % or more is 0.10 to 0.58 times the thickness of the external electrode. The multilayer electronic component according to any one of (1) to (7). (9) The thickness of the base electrode material diffused into the external electrode at 12.5 atomic % or more is between 2 / 3 and 3 / 2 of the thickness of the external electrode material diffused into the base electrode at 12.5 atomic % or more. The multilayer electronic component according to any one of (1) to (8). (10) the base electrode contains a first metal as a main component at least in a region away from the external electrode, the external electrode contains a second metal different from the first metal as a main component at least in a region away from the base electrode, In the diffusion layer, the first metal is diffused into the external electrode and the second metal is diffused into the base electrode, The diffusion layer has a cross section parallel to the lamination direction of 0.01 μm 2 The first metal is contained in an amount of 12.5 atomic % or more and the second metal is contained in an amount of 12.5 atomic % or more per area of ​​the first metal. The multilayer electronic component according to any one of (1) to (9). [Explanation of symbols]

[0136] 1...capacitor, 5...external electrode, 7...dielectric layer, 9...internal electrode, 11...active portion, 13...cover, 16...base electrode, 21...diffusion layer

Claims

1. an effective portion having dielectric layers and internal electrodes alternately stacked in a stacking direction; a cover overlapping the effective portion from the first side of a first side and a second side in the stacking direction; a base electrode overlapping the cover from the first side and containing a first metal as a main component; an external electrode overlapping the base electrode from the first side and containing a second metal different from the first metal as a main component, a first edge portion, which is an edge portion of the internal electrode, is in contact with the external electrode; the base electrode has a base diffusion layer in which the second metal contained in the external electrode is diffused in the base electrode at a concentration of 12.5 atomic % or more, The base diffusion layer is formed over the entire interface between the base electrode and the external electrode in a cross section parallel to the lamination direction. Multilayer electronic components.

2. The second metal is 12.5 atomic % or more, and the thickness of the second metal diffused into the base electrode is 0.25 to 0.88 times the thickness of the base electrode. The multilayer electronic component according to claim 1 .

3. The base electrode has a region buried in the cover. The multilayer electronic component according to claim 1 .

4. the base electrode has a second edge portion at an end thereof, the top surface and side surfaces of which are in contact with the external electrode; The second edge portion has the base diffusion layer over the entire thickness of the base electrode. The multilayer electronic component according to claim 1 .

5. The thickness of the portion of the external electrode where the second metal is diffused into the base electrode at 12.5 atomic % or more is greater than the length from the first edge portion of the portion of the external electrode where the second metal is diffused into the internal electrode at 12.5 atomic % or more. The multilayer electronic component according to claim 1 .

6. The cover is Two or more insulating layers stacked in the stacking direction; a dummy electrode located at the boundary of the two or more insulating layers, a third edge portion, which is an edge portion of the dummy electrode, is in contact with the external electrode; The thickness of the portion of the external electrode where the second metal is diffused into the base electrode at 12.5 atomic % or more is smaller than the length from the third edge portion of the portion of the external electrode where the second metal is diffused into the dummy electrode at 12.5 atomic % or more. The multilayer electronic component according to claim 1 .

7. The cover is Two or more insulating layers stacked in the stacking direction; a dummy electrode located at the boundary of the two or more insulating layers, a third edge of the dummy electrode contacts the external electrode; The length from the first edge of a portion of the external electrode where the second metal is diffused into the internal electrode at 12.5 atomic % or more is shorter than the length from the third edge of a portion of the external electrode where the second metal is diffused into the dummy electrode at 12.5 atomic % or more. The multilayer electronic component according to claim 1 .

8. The second metal contained in the external electrode is 12.5 atomic % or more and diffused into the base electrode to a thickness of 1.0 μm or more and 3.5 μm or less. The multilayer electronic component according to claim 1 .

9. The first metal contained in the base electrode is 12.5 atomic % or more and diffused into the external electrode to a thickness of 1.0 μm or more and 3.5 μm or less. The multilayer electronic component according to claim 1 .

10. the thickness of the second metal contained in the external electrode at 12.5 atomic % or more diffused into the base electrode is 2 / 3 to 3 / 2 of the thickness of the first metal contained in the base electrode at 12.5 atomic % or more diffused into the external electrode; The multilayer electronic component according to claim 1 .

11. the base electrode contains the first metal as a main component at least in a region farthest from the external electrode; the external electrode contains the second metal, which is different from the first metal, as a main component at least in a region farthest from the base electrode; In the base diffusion layer, the first metal is diffused into the external electrode and the second metal is diffused into the base electrode, The underlying diffusion layer has a cross section parallel to the lamination direction of 0.01 μm ２ The first metal is contained in an amount of 12.5 atomic % or more and the second metal is contained in an amount of 12.5 atomic % or more per area of ​​the first metal. The multilayer electronic component according to claim 1 .

12. The main component of the internal electrodes is Ni, The main component of the base electrode is Ni, The main component of the external electrodes is Cu. The multilayer electronic component according to claim 1 .

13. The external electrodes are plated films. The multilayer electronic component according to claim 1 .

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