Multilayer ceramic capacitor

Abstract

The present invention provides a multilayer ceramic capacitor which is not susceptible to the occurrence of a crack or the like in a ceramic element. This multilayer ceramic capacitor is provided with: a ceramic element which is obtained by stacking a plurality of ceramic layers, a plurality of first internal electrodes and a plurality of second internal electrodes in the height direction, and which has a first main surface and a second main surface opposite to each other in the height direction, a first end face and a second end face opposite to each other in the length direction that is perpendicular to the height direction, and a first lateral surface and a second lateral surface opposite to each other in the width direction that is perpendicular to the height direction and the length direction; and a first external electrode and a second external electrode, which are formed on the outer surface of the ceramic element. The first internal electrodes are led out in the first end face, and are electrically connected to the first external electrode; while the second internal electrodes are led out in the second end face, and are electrically connected to the second external electrode. If a cross-section that is parallel to the first lateral surface and the second lateral surface is examined, the first external electrode is formed in an L-shape on the first end face and the first main surface; the second external electrode is formed in an L-shape on the second end face and the first main surface; and the second main surface is provided with a plurality of embossed pores.

Description

Technical Field

[0001] The present invention relates to a multilayer ceramic capacitor.

Background Art

[0002] Multilayer ceramic capacitors are widely used in various devices such as electronic devices and electrical devices (hereinafter referred to as "electronic devices, etc."). For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2000-100647) discloses a multilayer ceramic capacitor having a typical structure.

[0003] Recently, miniaturization and high functionality of electronic devices, etc. have been rapidly progressing. Due to the miniaturization of electronic devices, etc., the internal volume (space volume) of electronic devices, etc. that houses an electronic circuit composed of electronic components has become extremely small. Also, due to the high functionality of electronic devices, etc., the number of electronic components required to constitute an electronic circuit has been rapidly increasing.

[0004] Therefore, along with the miniaturization and high functionality of electronic devices, etc., miniaturization, particularly thinning, is also required for the electronic components that constitute an electronic circuit. For example, in the case of multilayer ceramic capacitors, products with an extremely thin ceramic body having a thickness of several tens of μm have been put into practical use.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, along with the miniaturization and high functionality of electronic devices, etc., miniaturization, particularly thinning, of electronic components is required. However, in the case of multilayer ceramic capacitors, a decrease in mechanical strength against external forces has become a problem along with thinning.

[0007] In other words, multilayer ceramic capacitors, which are surface-mount electronic components, are often picked up by a nozzle of a mounting machine and transported to a predetermined position on a substrate or other surface for mounting. In this process, there was a risk that the thin multilayer ceramic capacitors could develop cracks (including fissures, breaks, and chips) in the ceramic body due to the impact of the nozzle. If cracks occurred in the ceramic body, there was a risk that the multilayer ceramic capacitor would develop an IR (insulation resistance) failure due to the intrusion of moisture from the outside.

[0008] Furthermore, multilayer ceramic capacitors are often sealed with resin after being mounted on a substrate or other surface. In this case, the bonding strength between the top surface (second main surface) of the ceramic element of the mounted multilayer ceramic capacitor and the resin was sometimes insufficient.

[0009] Therefore, the present invention aims to provide a multilayer ceramic capacitor that is less prone to defects such as cracks occurring in the ceramic element even when the ceramic element is subjected to impact by the nozzle when it is adsorbed by the nozzle of a mounting device. Furthermore, the present invention aims to provide a multilayer ceramic capacitor that has high bonding strength between the top surface (second main surface) of the ceramic element and the resin when it is mounted on a substrate or the like and then sealed with resin. [Means for solving the problem]

[0010] To solve the conventional problems described above, a multilayer ceramic capacitor according to one embodiment of the present invention comprises a ceramic body having a plurality of ceramic layers, a plurality of first internal electrodes, and a plurality of second internal electrodes stacked in the height direction, having a first main surface and a second main surface facing each other in the height direction, a first end surface and a second end surface facing each other in the length direction perpendicular to the height direction, and a first side surface and a second side surface facing each other in the width direction perpendicular to the height direction and the length direction, and a first external electrode and a second external electrode formed on the outer surface of the ceramic body, wherein the first internal electrode is drawn out to the first end surface and electrically connected to the first external electrode, and the second internal electrode is drawn out to the second end surface and electrically connected to the second external electrode, wherein when viewed in cross-section parallel to the first side surface and the second side surface, the first external electrode is formed in an L-shape on the first end surface and the first main surface, the second external electrode is formed in an L-shape on the second end surface and the first main surface, and a plurality of embossed holes are formed on the second main surface. [Effects of the Invention]

[0011] In one embodiment of the present invention, a multilayer ceramic capacitor has multiple embossed holes formed on its second main surface. Therefore, even when it is picked up by a nozzle of a mounting device, for example, it is resistant to impact, and the occurrence of cracks in the ceramic body is suppressed.

[0012] Furthermore, in one embodiment of the present invention, since a plurality of embossed holes are formed on the second main surface of the multilayer ceramic capacitor, when mounted on a substrate or the like and then sealed with resin, the bonding strength between the second main surface of the ceramic body and the resin is high. However, the multilayer ceramic capacitor of the present invention does not necessarily have to be sealed with resin after being mounted on a substrate or the like; it can also be used without being sealed with resin. [Brief explanation of the drawing]

[0013] [Figure 1]Figures 1(A) and 1(B) are perspective views of the multilayer ceramic capacitor 100 according to the first embodiment, with Figure 1(A) showing the multilayer ceramic capacitor 100 from the first main surface 1A side and Figure 1(B) showing the multilayer ceramic capacitor 100 from the second main surface 1B side. [Figure 2] This is a cross-sectional view of the multilayer ceramic capacitor 100, showing the cross-section of the XX portion indicated by the dashed-dotted arrow in Figure 1(A). [Figure 3] This is a cross-sectional view of the main part of the multilayer ceramic capacitor 100. [Figure 4] Figures 4(A) to 4(D) are explanatory diagrams showing the steps in an example of a manufacturing method for a multilayer ceramic capacitor 100. [Figure 5] Figures 5(E) to 5(J) are a continuation of Figure 4(D) and are explanatory diagrams showing the steps in an example of a manufacturing method for a multilayer ceramic capacitor 100. [Figure 6] This is a cross-sectional view of a multilayer ceramic capacitor 200 according to a second embodiment. [Figure 7] Figures 7(A) to 7(D) are explanatory diagrams showing the steps in an example of a manufacturing method for a multilayer ceramic capacitor 200. [Figure 8] Figures 8(E) to 8(I) are a continuation of Figure 7(D) and are explanatory diagrams showing the steps in an example of a manufacturing method for a multilayer ceramic capacitor 200. [Modes for carrying out the invention]

[0014] The embodiments for carrying out the present invention will be described below with reference to the drawings.

[0015] In addition, each embodiment illustratively shows an embodiment of the present invention, and the present invention is not limited to the content of the embodiment. It is also possible to combine the content described in different embodiments and implement it, and the implementation content in that case is also included in the present invention. In addition, the drawings are for assisting in understanding the specification, and may be drawn schematically. There may be cases where the drawn component or the ratio of the dimensions between components does not match the ratio of those dimensions described in the specification. Also, there may be cases where the components described in the specification are omitted in the drawings or the number is omitted in the drawing.

[0016] [First Embodiment] FIG. 1(A), (B), FIG. 2, and FIG. 3 show a multilayer ceramic capacitor 100 according to the first embodiment. However, FIGS. 1(A) and (B) are perspective views of the multilayer ceramic capacitor 100, respectively. FIG. 1(A) shows the multilayer ceramic capacitor 100 from the side of the first main surface 1A, and FIG. 1(B) shows the multilayer ceramic capacitor 100 from the side of the second main surface 1B. FIG. 2 is a cross-sectional view of the multilayer ceramic capacitor 100, showing the cross-section of the portion X-X indicated by the dashed-dotted arrow in FIG. 1(A). FIG. 3 is a cross-sectional view of the main part of the multilayer ceramic capacitor 100.

[0017] Note that the drawings show the height direction T, length direction L, and width direction W of the multilayer ceramic capacitor 100, and in the following description, reference may be made to these directions. In the present embodiment, the stacking direction of the ceramic layer 1a described later is the height direction T of the multilayer ceramic capacitor 100.

[0018] The multilayer ceramic capacitor 100 includes a ceramic body 1. The ceramic body 1 is in the shape of a rectangular parallelepiped and has a first main surface 1A and a second main surface 1B facing each other in the height direction T, a first end surface 1C and a second end surface 1D facing each other in the length direction L, and a first side surface 1E and a second side surface 1F facing each other in the width direction W.

[0019] The dimensions of the ceramic body 1 are arbitrary. For example, it is also preferable that one of the dimensions in the length direction L and the dimension in the width direction W is 1.0 mm or less, and the other is 0.5 mm or less. Further, it is also preferable that the dimension in the height direction T is 0.1 mm or less. When the present invention is implemented, even in the case of the laminated ceramic capacitor 100 which is miniaturized and thinned in this way, as will be described later, by forming a plurality of emboss holes 10 in the second main surface 1B of the ceramic body 1, the impact resistance is improved, and the occurrence of cracks or the like in the ceramic body 1 is suppressed.

[0020] The ceramic body 1 is composed of a laminated ceramic layer 1a, a first internal electrode 2, a second internal electrode 3, and a dummy internal electrode 4. The ceramic layer 1a, the first internal electrode 2, the second internal electrode 3, and the dummy internal electrode 4 are laminated in the height direction T of the ceramic body 1.

[0021] Note that the dummy internal electrode 4 is mainly not provided for forming capacitance, but is an electrode provided as a base external electrode for the first external electrode 5 and the second external electrode 6, as will be described later.

[0022] The material of the ceramic body 1 (ceramic layer 1a) is arbitrary. For example, dielectric ceramics mainly composed of BaTiO3 can be used. However, instead of BaTiO3, dielectric ceramics mainly composed of other materials such as CaTiO3, SrTiO3, and CaZrO3 may be used.

[0023] The thickness of the ceramic layer 1a is arbitrary. For example, in the effective region for forming capacitance where the first internal electrode 2 and the second internal electrode 3 are formed, it can be about 0.3 μm to 2.0 μm.

[0024] The number of layers of the ceramic layer 1a is arbitrary. For example, in the effective region for forming capacitance where the first internal electrode 2 and the second internal electrode 3 are formed, it can be about 1 layer to 6000 layers.

[0025] On both the upper and lower sides of the ceramic body 1, a protective layer (outer layer) is provided, consisting only of a ceramic layer 1a, without the first internal electrode 2 and the second internal electrode 3 being formed. However, in this embodiment, a dummy internal electrode 4 is formed on the protective layer. The thickness of the protective layer is arbitrary, but can be, for example, about 5 μm to 150 μm. The thickness of the ceramic layer 1a of the protective layer may be greater than the thickness of the ceramic layer 1a in the effective region of capacitance formation where the first internal electrode 2 and the second internal electrode 3 are formed. Furthermore, the material of the ceramic layer 1a of the protective layer may be different from the material of the ceramic layer 1a in the effective region.

[0026] As can be seen in Figure 2, the first internal electrode 2 extends in the longitudinal direction L of the ceramic body 1, with one end drawn out to the first end face 1C of the ceramic body 1. The second internal electrode 3 extends in the longitudinal direction L of the ceramic body 1, with one end drawn out to the second end face 1D of the ceramic body 1. In principle, it is preferable that the first internal electrode 2 and the second internal electrode 3 are stacked alternately.

[0027] The dummy internal electrode 4, provided as a base external electrode for the first external electrode 5 and the second external electrode 6, has a smaller length L dimension than the first internal electrode 2 and the second internal electrode 3. One end of the dummy internal electrode 4 is drawn out to either the first end face 1C or the second end face 1D of the ceramic body 1. Furthermore, the dummy internal electrode 4 positioned closest to the first main surface 1A of the ceramic body 1 is exposed to the first main surface 1A of the ceramic body 1.

[0028] Furthermore, the dummy internal electrode 4 is positioned at least one layer on the first main surface 1A side of the ceramic body 1, in the case of the first external electrode 5 and the second external electrode 6, and exposed on the first main surface of the ceramic body 1.

[0029] The main component (metal component) of the first internal electrode 2, the second internal electrode 3, and the dummy internal electrode 4 can be any material, but in this embodiment, Ni was used. However, other metals such as Cu, Ag, Pd, and Au may be used instead of Ni. Also, Ni, Cu, Ag, Pd, and Au may be alloys with other metals. The first internal electrode 2, the second internal electrode 3, and the dummy internal electrode 4 may contain other components such as ceramics in addition to the metal component.

[0030] The thicknesses of the first internal electrode 2, the second internal electrode 3, and the dummy internal electrode 4 are arbitrary, but can be, for example, approximately 0.3 μm to 1.5 μm.

[0031] A first external electrode 5 and a second external electrode 6 are formed on the outer surface of the ceramic body 1. When viewed in a cross-section parallel to the first side surface 1E and the second side surface 1F, the first external electrode 5 is formed in an L-shape on the first end surface 1C and the first main surface 1A, and the second external electrode 6 is formed in an L-shape on the second end surface 1D and the first main surface 1A. The first external electrode 5 is electrically connected to the first internal electrode 2 at the first end surface 1C. The second external electrode 6 is electrically connected to the second internal electrode 3 at the second end surface 1D.

[0032] The first external electrode 5 and the second external electrode 6 have the same multilayer structure. In this embodiment, the first external electrode 5 and the second external electrode 6 are comprised, from bottom to top, a base external electrode, a Cu-plated external electrode layer 7 formed on the outside of the base external electrode, a Ni-plated external electrode layer 8 formed on the outside of the Cu-plated external electrode layer 7, and an Au-plated external electrode layer 9 formed on the outside of the Ni-plated external electrode layer 8. However, the structure and materials of the first external electrode 5 and the second external electrode 6 are arbitrary and not limited to these structures and materials. Also, the dimensions such as the thickness, width, and length of the first external electrode 5 and the second external electrode 6 are arbitrary and can be freely set. In particular, various variations can be adopted regarding the number of layers, material, and dimensions of the plated external electrode layers.

[0033] Next, we will explain the base external electrodes for the first external electrode 5 and the second external electrode 6. The base external electrode is the layer that serves as the base when forming the plated external electrode layer on its outside.

[0034] The base external electrode of the first external electrode 5 is composed of the ends of the first internal electrode 2 and dummy internal electrode 4 that are drawn out to the first end face 1C, and the main surface of the dummy internal electrode 4 that is exposed to the first main surface 1A. Figure 2 illustrates a structure in which the first external electrode 5 has four layers of dummy internal electrodes 4 as the base external electrode, with the upper main surface of the dummy internal electrode 4 located closest to the first main surface 1A being exposed to the first main surface 1A, and the ends of the remaining three layers of dummy internal electrodes 4 being drawn out to the first end face 1C. However, the number of layers of the dummy internal electrode 4 of the first external electrode 5 is arbitrary, and it is sufficient to have at least one layer located closest to the first main surface 1A of the ceramic body 1, with its upper main surface exposed to the outside from the first main surface 1A of the ceramic body 1.

[0035] Similarly, the base external electrode of the second external electrode 6 is composed of the ends of the second internal electrode 3 and dummy internal electrode 4 that are drawn out to the second end face 1D, and the main surface of the dummy internal electrode 4 that is exposed to the first main surface 1A. Figures 2 and 3 illustrate a structure in which the second external electrode 6 has four layers of dummy internal electrodes 4 as the base external electrode, with the upper main surface of the dummy internal electrode 4 located closest to the first main surface 1A being exposed to the first main surface 1A, and the ends of the remaining three layers of dummy internal electrodes 4 being drawn out to the second end face 1D. However, the number of layers of the dummy internal electrode 4 of the second external electrode 6 is arbitrary, and it is sufficient to have at least one layer located closest to the first main surface 1A of the ceramic body 1, with its upper main surface exposed to the outside from the first main surface 1A of the ceramic body 1.

[0036] As described above, the ends of the first internal electrode 2 drawn out to the first end face 1C of the ceramic body 1, and the ends of the second internal electrode 3 drawn out to the second end face 1D of the ceramic body 1, are also part of the base external electrodes of the first external electrode 5 and the second external electrode 6. In Figures 2 and 3, to avoid making the drawings too complex, the ends of the first internal electrode 2 and the ends of the second internal electrode 3 are not shown as parts of the first external electrode 5 and the second external electrode 6 (the leader lines from the reference numeral "5" indicating the first external electrode 5 and the reference numeral "6" indicating the second external electrode 6 in the figures have been omitted).

[0037] The base external electrodes of the first external electrode 5 and the second external electrode 6 function as a base for forming the Cu plated external electrode layer 7 on their outside. As described above, in this embodiment, the ends of the first internal electrode 2 and the dummy internal electrode 4 drawn out to the first end face 1C, the ends of the second internal electrode 3 and the dummy internal electrode 4 drawn out to the second end face 1D are also part of the base external electrodes of the first external electrode 5 and the second external electrode 6. On the first end face 1C, the ends of multiple linear first internal electrodes 2 and the ends of the dummy internal electrode 4, which extend in the width direction W, are exposed at intervals (with the ends of linear ceramic layers 1a, which extend in the width direction W, in between). On the second end face 1D, the ends of multiple linear second internal electrodes 3 and the ends of the dummy internal electrode 4, which extend in the width direction W, are exposed at intervals. However, even though the ends of the first internal electrodes 2, the second internal electrodes 3, and the dummy internal electrode 4 are spaced apart, they function as a base layer when forming the plated external electrode layer.

[0038] The first external electrode 5 and the second external electrode 6 are provided with a Cu-plated external electrode layer 7 on the outside of the underlying external electrode. The Cu-plated external electrode layer 7 primarily serves to improve moisture resistance. It is also preferable that the Cu-plated external electrode layer 7 contains Ni. In this case, dissolution of the external electrode layer into the solder can be suppressed.

[0039] The first external electrode 5 and the second external electrode 6 are provided with a Ni-plated external electrode layer 8 on the outside of the Cu-plated external electrode layer 7. The Ni-plated external electrode layer 8 primarily serves to improve solder heat resistance and bonding properties. It is also preferable that the Ni-plated external electrode layer 8 contains phosphorus (P). In this case, the mechanical strength of the external electrode layer can be improved.

[0040] The first external electrode 5 and the second external electrode 6 are equipped with an Au-plated external electrode layer 9 on the outside of the Ni-plated external electrode layer 8. The Au-plated external electrode layer 9 primarily serves to improve the wettability of the external electrode layer to solder.

[0041] In this embodiment, the multilayer ceramic capacitor 100 has a radius radius (R) where the first main surface 1A meets the first end surface 1C, second end surface 1D, first side surface 1E, and second side surface 1F, which is greater than the radius radius where the second main surface 1B meets the first end surface 1C, second end surface 1D, first side surface 1E, and second side surface 1F. The radius radius where the first main surface 1A meets the first end surface 1C, second end surface 1D, first side surface 1E, and second side surface 1F is preferably, for example, 1 μm or more and 10 μm or less. On the other hand, the radius radius where the second main surface 1B meets the second end surface 1D, first side surface 1E, and second side surface 1F is preferably, for example, less than 1 μm.

[0042] In the multilayer ceramic capacitor 100 of this embodiment, the first main surface 1A of the ceramic body 1, which is equipped with a first external electrode 5 and a second external electrode 6, is the mounting surface for a substrate or the like. Because the radius (R) of the edges where the first main surface 1A, which is the mounting surface, and the first end face 1C, second end face 1D, first side surface 1E, and second side surface 1F meet is large (largely rounded), when the multilayer ceramic capacitor 100 is placed on a substrate or the like for mounting, even if these edges or the corners where the first main surface 1A and two surfaces selected from the first end face 1C, second end face 1D, first side surface 1E, and second side surface 1F meet collide with the substrate or the like, cracks and the like are suppressed from occurring in the ceramic body 1.

[0043] As mentioned above, the radius radius (R) of the ridge where the first main surface 1A and the first end surface 1C, second end surface 1D, first side surface 1E, and second side surface 1F meet is preferably, for example, between 1 μm and 10 μm. If it is less than 1 μm, the effect of suppressing the occurrence of cracks in the ceramic body 1 is small. If it exceeds 10 μm, the effective volume of the ceramic body 1 becomes small, which may hinder the formation of the first internal electrode 2 and the second internal electrode 3, potentially reducing the capacitance of the multilayer ceramic capacitor 100.

[0044] In this embodiment, the multilayer ceramic capacitor 100 has a plurality of embossed holes 10 formed on the second main surface 1B of the ceramic body 1. In this embodiment, a plurality of embossed holes 10 of the same shape and dimensions are formed on the second main surface 1B of the ceramic body 1, aligned in the length direction L and the width direction W.

[0045] In this application, an embossed hole refers to a concave, bottomed hole. The concave surface may be hemispherical or non-hemispherical. The dimensions, number, arrangement, spacing, and area of ​​the embossed holes 10 are arbitrary and can be set as appropriate. The method of forming the embossed holes 10 is also arbitrary. Whether or not embossed holes 10 are formed on the second main surface 1B can be easily confirmed by comparing it with other surfaces of the ceramic body 1 (for example, the first main surface 1A).

[0046] In the multilayer ceramic capacitor 100, the second main surface 1B of the ceramic body 1 is the surface that is attracted by, for example, the nozzle of a mounting device during mounting, and is therefore susceptible to impact from the nozzle. In this embodiment, the multilayer ceramic capacitor 100 has multiple embossed holes 10 formed on the second main surface 1B of the ceramic body 1, so that even if an impact is applied by a nozzle or the like, it is resistant to impact and the occurrence of cracks in the ceramic body 1 is suppressed. The embossed holes 10 are fine, with a depth that fits within one to several tens of layers of ceramic layers 1a, and this can effectively improve the impact resistance of the ceramic body 1. However, if the depth of the embossed holes 10 becomes too large, it may conversely reduce the overall strength of the ceramic body 1, so it is necessary not to make the depth of the embossed holes 10 too large.

[0047] The multilayer ceramic capacitor 100 of this embodiment can be manufactured, for example, by the method shown in Figures 4(A) to 5(J).

[0048] First, a ceramic green sheet 11a is prepared for fabricating the ceramic layer 1a of the ceramic substrate 1, as shown in Figure 4(A). The ceramic green sheet 11a is prepared as a mother ceramic green sheet 50, in which numerous ceramic green sheets 11a are arranged in a matrix, in order to manufacture a large number of multilayer ceramic capacitors 100 at once.

[0049] Although not shown in the diagram, first, dielectric ceramic powder, binder resin, solvent, etc. are prepared, and these are wet-mixed to create a ceramic slurry.

[0050] Next, the ceramic slurry is applied to the carrier film in a sheet-like manner using a die coater, gravure coater, microgravure coater, etc., and dried to produce a mother ceramic green sheet 50.

[0051] Next, as also shown in Figure 4(A), conductive paste 12 for forming the first internal electrode 2, conductive paste 13 for forming the second internal electrode 3, and conductive paste 14 for forming the dummy internal electrode 4, which have been prepared in advance, are applied (e.g., printed) in a desired pattern shape to the main surface of a predetermined ceramic green sheet 11a in the mother ceramic green sheet 50. For the conductive paste, for example, a mixture of a solvent, binder resin, metal powder (e.g., Ni powder) can be used.

[0052] Next, as shown in Figure 4(B), the mother ceramic green sheets 50 are stacked in a predetermined order and pressed together to produce a mother unfired ceramic body 60 in which a large number of unfired ceramic bodies 11 are arranged in a matrix.

[0053] Next, as shown in Figure 4(C), a jig 70 is prepared, having multiple protrusions 70a formed on its upper main surface. Subsequently, the lower main surface of the mother unfired ceramic body 60 is pressed against the protrusions 70a of the jig 70. As a result, as shown in Figure 4(D), multiple embossed holes 10 are formed on the second main surface 1B of each unfired ceramic body 11 of the mother unfired ceramic body 60.

[0054] Next, as shown in Figure 5(E), the mother unfired ceramic body 60 is cut into individual unfired ceramic bodies 11.

[0055] Next, the unfired ceramic body 11 is fired according to a predetermined profile to produce the ceramic body 1 shown in Figure 5(F). At this time, conductive paste 12 is fired simultaneously inside the ceramic body 1 to form the first internal electrode 2, conductive paste 13 is fired simultaneously to form the second internal electrode 3, and conductive paste 14 is fired simultaneously to form the dummy internal electrode 4.

[0056] Next, a jig 80 is prepared as shown in Figure 5(G). The second main surface 1B of the ceramic body 1 is then fixed to the upper main surface of the jig 80. Subsequently, for example, sandblasting is performed to remove the first main surface 1A of the ceramic body 1, exposing the upper main surface of the dummy internal electrode 4, which is located closest to the first main surface 1A of the ceramic body 1, to the first main surface 1A of the ceramic body 1.

[0057] At the same time, the edges where the first main surface 1A meets the first end surface 1C, the second end surface 1D, the first side surface 1E, and the second side surface 1F are rounded, and the radius (R) of the edges where the first main surface 1A meets the first end surface 1C, the second end surface 1D, the first side surface 1E, and the second side surface 1F becomes larger than the radius (R) of the edges where the second main surface 1B meets the first end surface 1C, the second end surface 1D, the first side surface 1E, and the second side surface 1F (they become more rounded).

[0058] Next, as shown in Figure 5(H), the ends of the first internal electrode 2, the second internal electrode 3, and the dummy internal electrode 4, which are drawn out to the first end face 1C and the second end face 1D, and the upper main surface of the dummy internal electrode 4 exposed on the first main surface 1A are used as the base external electrodes. After applying a predetermined catalyst to the surface of these base external electrodes as needed, electroless plating is performed to form a Cu plated external electrode layer 7.

[0059] Next, as shown in Figure 5(I), a predetermined catalyst is applied to the outside of the Cu-plated outer electrode layer 7 as needed, and then electroless plating is performed to form the Ni-plated outer electrode layer 8.

[0060] Next, as shown in Figure 5(J), an electroless plating process is performed on the outside of the Ni-plated external electrode layer 8, after applying a predetermined catalyst as needed, to form the Au-plated external electrode layer 9. As a result, the first external electrode 5 is formed in an L-shape on the first end face 1C and the first main surface 1A of the ceramic body 1, and the second external electrode 6 is formed in an L-shape on the second end face 1D and the first main surface 1A of the ceramic body 1, completing the multilayer ceramic capacitor 100 according to the first embodiment.

[0061] [Second Embodiment] Figure 6 shows a multilayer ceramic capacitor 200 according to the second embodiment. However, Figure 6 is a cross-sectional view of the multilayer ceramic capacitor 200.

[0062] The multilayer ceramic capacitor 200 according to the second embodiment has some modifications to the configuration of the multilayer ceramic capacitor 100 according to the first embodiment described above.

[0063] Specifically, in the multilayer ceramic capacitor 100, the radius radius (R) of the ridge where the first main surface 1A meets the first end surface 1C, second end surface 1D, first side surface 1E, and second side surface 1F in the ceramic body 1 was larger than the radius radius of the ridge where the second main surface 1B meets the first end surface 1C, second end surface 1D, first side surface 1E, and second side surface 1F. In the multilayer ceramic capacitor 200, this was changed so that the radius radius of the ridge where the first main surface 1A meets the first end surface 1C, second end surface 1D, first side surface 1E, and second side surface 1F is the same as, or approximately the same as, the radius radius of the ridge where the second main surface 1B meets the first end surface 1C, second end surface 1D, first side surface 1E, and second side surface 1F.

[0064] As a result, when comparing the multilayer ceramic capacitor 100 and the multilayer ceramic capacitor 200, the radius radius (R) of the ridge where the first main surface 1A of the ceramic body 1 of the multilayer ceramic capacitor 200 touches the first end surface 1C, the second end surface 1D, the first side surface 1E, and the second side surface 1F is smaller than the radius radius of the ridge where the first main surface 1A of the ceramic body 1 of the multilayer ceramic capacitor 100 touches the first end surface 1C, the second end surface 1D, the first side surface 1E, and the second side surface 1F.

[0065] Furthermore, in the multilayer ceramic capacitor 100, a dummy internal electrode 4 was used as part of the base external electrode for the first external electrode 5 and the second external electrode 6. The multilayer ceramic capacitor 200 changed this and omitted the dummy internal electrode 4. Instead, the multilayer ceramic capacitor 200 formed a NiCr thin film layer 27 by sputtering as the base external electrode for the first external electrode 25 and the second external electrode 26. The NiCr thin film layer 27 has high adhesion to the ceramic body 1 and makes an excellent base external electrode for the first external electrode 25 and the second external electrode 26.

[0066] Furthermore, in the multilayer ceramic capacitor 100, the first external electrode 5 and the second external electrode 6 were plated external electrode layers consisting of a Cu plated external electrode layer 7, a Ni plated external electrode layer 8, and an Au plated external electrode layer 9 in that order on the outside of the underlying external electrode. The multilayer ceramic capacitor 200 modified this by forming a Ni plated external electrode layer 28 and an Au plated external electrode layer 29 in that order on the outside of the underlying external electrode, which is the NiCr thin film layer 27, as the plated external electrode layers for the first external electrode 25 and the second external electrode 26.

[0067] The other configurations of the multilayer ceramic capacitor 200 were the same as those of the multilayer ceramic capacitor 100.

[0068] Similar to the multilayer ceramic capacitor 100, the multilayer ceramic capacitor 200 has multiple embossed holes 10 formed on the second main surface 1B of the ceramic body 1. Therefore, even if the second main surface 1B of the ceramic body 1 of the multilayer ceramic capacitor 200 is subjected to impact by a nozzle or the like during mounting, it is resistant to impact, and the occurrence of cracks in the ceramic body 1 is suppressed.

[0069] The multilayer ceramic capacitor 200 of this embodiment can be manufactured, for example, by the method shown in Figures 7(A) to 8(I).

[0070] First, a ceramic green sheet 11a is prepared for fabricating the ceramic layer 1a of the ceramic substrate 1, as shown in Figure 7(A). The ceramic green sheet 11a is prepared as a mother ceramic green sheet 50 for the batch manufacturing of a large number of multilayer ceramic capacitors 100.

[0071] Next, as shown in Figure 7(A), the conductive paste 12 for forming the first internal electrode 2 and the conductive paste 13 for forming the second internal electrode 3, which have been prepared in advance, are applied to the main surface of a predetermined ceramic green sheet 11a in the mother ceramic green sheet 50 in the desired pattern shape. Note that since the multilayer ceramic capacitor 200 does not have dummy internal electrodes, conductive paste for forming dummy internal electrodes is not applied.

[0072] Next, as shown in Figure 7(B), the mother ceramic green sheets 50 are stacked in a predetermined order and pressed together to produce the mother unfired ceramic body 60.

[0073] Next, as shown in Figure 7(C), the lower main surface of the mother unfired ceramic body 60 is pressed against a jig 70 having multiple protrusions 70a formed on its upper main surface, and as shown in Figure 7(D), multiple embossed holes 10 are formed on the second main surface 1B of each unfired ceramic body 11.

[0074] Next, as shown in Figure 8(E), the mother unfired ceramic body 60 is cut into individual unfired ceramic bodies 11.

[0075] Next, the unfired ceramic body 11 is fired according to a predetermined profile to produce the ceramic body 1 shown in Figure 8(F).

[0076] Next, as shown in Figure 8(G), a NiCr thin film layer 27 is formed by sputtering as the base external electrode for the first external electrode 25 and the second external electrode 26.

[0077] Next, as shown in Figure 8(H), a Ni-plated external electrode layer 28 is formed by applying electroless plating to the outside of the NiCr thin film layer 27, which is the base external electrode for the first external electrode 25 and the second external electrode 26, after applying a predetermined catalyst as needed.

[0078] Next, as shown in Figure 8(I), an electroless plating process is performed on the outside of the Ni-plated external electrode layer 28, after applying a predetermined catalyst as needed, to form the Au-plated external electrode layer 29. As a result, the first external electrode 25 is formed in an L-shape on the first end face 1C and the first main surface 1A of the ceramic body 1, and the second external electrode 26 is formed in an L-shape on the second end face 1D and the first main surface 1A of the ceramic body 1, completing the multilayer ceramic capacitor 200 according to the second embodiment.

[0079] The multilayer ceramic capacitors 100 and 200 according to the embodiments have been described above. However, the present invention is not limited to the above-described content, and various modifications can be made in accordance with the spirit of the invention.

[0080] For example, in the above embodiment, a jig 70 having a plurality of protrusions 70a formed on its upper main surface was prepared, and the second main surface 1B of the unfired ceramic body 11 was pressed against the protrusions 70a of the jig 70, and then the unfired ceramic body 11 was fired to form a plurality of embossed holes 10 on the second main surface 1B. However, the method for forming the embossed holes 10 on the second main surface 1B of the ceramic body 1 is not limited to this method, and various methods can be employed. As stated above, in this application, an embossed hole refers to a concave bottomed hole, and the method of manufacturing it is not limited. The embossed hole (concave bottomed hole) may be hemispherical or non-hemispherical.

[0081] Furthermore, in the above embodiment, the embossed holes 10 are formed on the entire surface of the second main surface 1B of the ceramic body 1, but the embossed holes 10 may be formed in only a portion of the second main surface 1B of the ceramic body 1.

[0082] Furthermore, in the above embodiment, multiple embossed holes 10 of the same shape and dimensions are formed on the second main surface 1B of the ceramic body 1, aligned in the length direction L and width direction W of the ceramic body 1. However, the shape and dimensions of individual embossed holes 10 may differ, and the multiple embossed holes 10 do not have to be formed in an aligned state.

[0083] A multilayer ceramic capacitor according to one embodiment of the present invention is as described in the "Means for Solving the Problem" section.

[0084] In this multilayer ceramic capacitor, it is also preferable that the radius (R) of the ridge where the first main surface and the first end surface, second end surface, first side surface, and second side surface meet is larger than the radius (R) of the ridge where the second main surface and the first end surface, second end surface, first side surface, and second side surface meet. In one embodiment of the multilayer ceramic capacitor, the first main surface is the mounting surface for a substrate, etc. In this case, because the radius (R) of the ridge where the first main surface, which is the mounting surface, and the first end surface, second end surface, first side surface, and second side surface meet is large, when the multilayer ceramic capacitor is placed on a substrate for mounting, even if these ridges or the corners where the first main surface and two surfaces selected from the first end surface, second end surface, first side surface, and second side surface meet collide with the substrate, etc., the occurrence of cracks in the ceramic body is suppressed.

[0085] Furthermore, it is preferable that the radius (R) of the edges where the first main surface and the first end face, second end face, first side surface, and second side surface meet is between 1 μm and 10 μm. If it is less than 1 μm, the effect of suppressing crack formation in the ceramic body when these edges collide with a substrate or the like is small. If it exceeds 10 μm, the effective volume of the ceramic body becomes small, which may hinder the formation of the first and second internal electrodes and reduce the capacitance of the multilayer ceramic capacitor.

[0086] It is also preferable that the first external electrode and the second external electrode each include a base external electrode and at least one plated external electrode layer formed on the outside of the base external electrode. In this case, the base external electrode can be used as a base, and the plated external electrode layer can be easily formed on the outside thereon, for example, by electroless plating.

[0087] Furthermore, it is preferable that the underlying external electrode has a smaller length dimension than the first and second internal electrodes and includes a dummy internal electrode exposed on the first main surface of the ceramic body. In this case, the first and second external electrodes, which have a relatively large area on the first main surface of the ceramic body, can be easily formed.

[0088] It is also preferable that the dummy internal electrode, the first internal electrode, and the second external electrode are formed from the same material. In this case, there is no need to prepare separate material to form the dummy internal electrode, which is the base external electrode, and the productivity of multilayer ceramic capacitors is improved.

[0089] In this case, it is also preferable that the dummy internal electrode has Ni as its main component. In this case, the ceramic body, the first internal electrode, the second external electrode, and the dummy internal electrode can be easily manufactured by so-called co-firing.

[0090] It is also preferable that the underlying external electrode be a thin film. In this case, the underlying external electrode can be easily formed, for example, by sputtering.

[0091] In this case, it is also preferable for the thin film to be mainly composed of NiCr. In this case, it has high adhesion to the ceramic substrate and serves as an excellent base external electrode for the first external electrode and the second external electrode.

[0092] It is also preferable that the plated external electrode layer includes at least one selected from a Cu plated external electrode layer, a Ni plated external electrode layer, and an Au plated external electrode layer. In this case, various functions can be exhibited in each plated external electrode layer, and excellent first and second external electrodes can be formed.

[0093] It is also preferable that the plated external electrode layer includes a Ni plated external electrode layer formed on the outside of the underlying external electrode and an Au plated external electrode layer formed on the outside of the Ni plated external electrode layer. In this case, the Ni plated external electrode layer can mainly perform the function of improving solder heat resistance and bonding performance, and the Au plated external electrode layer 9 can mainly perform the function of improving the solder wettability of the external electrode layer.

[0094] It is also preferable that the plated external electrode layer includes a Cu plated external electrode layer formed on the outside of the underlying external electrode, a Ni plated external electrode layer formed on the outside of the Cu plated external electrode layer, and an Au plated external electrode layer formed on the outside of the Ni plated external electrode layer. In this case, the Cu plated external electrode layer 7 can mainly perform the function of improving moisture resistance, the Ni plated external electrode layer can mainly perform the function of improving solder heat resistance and bonding performance, and the Au plated external electrode layer 9 can mainly perform the function of improving the solder wettability of the external electrode layer.

[0095] It is also preferable that the Ni-plated external electrode layer contains phosphorus (P). In this case, the mechanical strength of the external electrode layer can be improved.

[0096] It is also preferable that the Cu-plated external electrode layer contains Ni. In this case, the dissolution of the external electrode layer into the solder can be suppressed.

[0097] It is also preferable that one of the dimensions in the length direction and the width direction is 1.0 mm or less, and the other is 0.5 mm or less. Furthermore, it is also preferable that the dimension in the height direction is 0.1 mm or less. In this way, even when the present invention is applied to a miniaturized and thin-layer multilayer ceramic capacitor, the impact resistance is improved by the embossed holes formed on the second main surface of the ceramic body, and the occurrence of cracks in the ceramic body is suppressed. [Explanation of symbols]

[0098] 1. Ceramic base 1a. Ceramic layer 1A...First main surface 1B...Second main surface 1C...1st end surface 1D...Second end face 1E...1st side 1F...2nd side 2...1st internal electrode 3...Second internal electrode 4. Dummy internal electrodes 5...1st external electrode 6...Second external electrode 7. Cu plated external electrode layer 8, 28...Ni plated external electrode layer 9, 29...Au plated external electrode layer 27...NiCr thin film layer (base external electrode) 10 embossed holes

Claims

1. A ceramic body comprising multiple ceramic layers, multiple first internal electrodes, and multiple second internal electrodes stacked in the height direction, having a first main surface and a second main surface facing each other in the height direction, a first end surface and a second end surface facing each other in the length direction perpendicular to the height direction, and a first side surface and a second side surface facing each other in the width direction perpendicular to the height direction and the length direction, The ceramic body comprises a first external electrode and a second external electrode formed on its outer surface, The first internal electrode is drawn out to the first end face and electrically connected to the first external electrode. The multilayer ceramic capacitor is characterized in that the second internal electrode is drawn out to the second end face and electrically connected to the second external electrode, When viewing a cross-section parallel to the first and second sides, The first external electrode is formed in an L-shape on the first end face and the first main face, The second external electrode is formed in an L-shape on the second end face and the first main face, Multiple embossed holes are formed on the second main surface. The first main surface does not have the plurality of embossed holes formed on it. Multilayer ceramic capacitor.

2. The radius (R) of the ridge where the first main surface and the first end surface, second end surface, first side surface, and second side surface meet is, The radius of the ridge where the second main surface and the first end surface, the second end surface, the first side surface, and the second side surface meet is larger than the radius of the ridge. A multilayer ceramic capacitor as described in claim 1.

3. The radius (R) of the ridge where the first main surface and the first end surface, second end surface, first side surface, and second side surface meet is, It is between 1 μm and 10 μm. A multilayer ceramic capacitor according to claim 1 or 2.

4. The first external electrode and the second external electrode are, Substrate exterior electrode and Including at least one plated external electrode layer formed on the outside of the aforementioned underlayment external electrode, A multilayer ceramic capacitor according to claim 1 or 2.

5. The aforementioned external electrode for the substrate, A dummy internal electrode having a smaller length dimension than the first internal electrode and the second internal electrode, and exposed on the first main surface of the ceramic body, A multilayer ceramic capacitor as described in claim 4.

6. The dummy internal electrode, the first internal electrode, and the second internal electrode are formed of the same material. A multilayer ceramic capacitor as described in claim 5.

7. The dummy internal electrode is composed mainly of Ni, A multilayer ceramic capacitor as described in claim 5.

8. The aforementioned external electrode of the substrate is a thin film. A multilayer ceramic capacitor as described in claim 4.

9. The thin film is mainly composed of NiCr, A multilayer ceramic capacitor as described in claim 8.

10. The aforementioned plated external electrode layer It includes at least one selected from a Cu-plated external electrode layer, a Ni-plated external electrode layer, and an Au-plated external electrode layer. A multilayer ceramic capacitor as described in claim 4.

11. The aforementioned plated external electrode layer A Ni-plated external electrode layer formed on the outside of the aforementioned base external electrode, Including an Au-plated external electrode layer formed on the outside of the Ni-plated external electrode layer, A multilayer ceramic capacitor as described in claim 10.

12. The aforementioned plated external electrode layer The Cu plated outer electrode layer formed on the outside of the aforementioned base outer electrode, A Ni-plated external electrode layer formed on the outside of the Cu-plated external electrode layer, Including an Au-plated external electrode layer formed on the outside of the Ni-plated external electrode layer, A multilayer ceramic capacitor as described in claim 10.

13. The Ni-plated external electrode layer contains P, A multilayer ceramic capacitor as described in claim 10.

14. The Cu-plated external electrode layer contains Ni, A multilayer ceramic capacitor as described in claim 10.

15. The lengthwise dimension and the widthwise dimension are 1.0 mm or less, and the other is 0.5 mm or less. A multilayer ceramic capacitor according to claim 1 or 2.

16. The aforementioned height dimension is 0.1 mm or less. A multilayer ceramic capacitor according to claim 1 or 2.

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