Electronic component and method for manufacturing electronic component

Abstract

This electronic component comprises an electronic component element assembly, a first external electrode, a second external electrode, a third external electrode, and a fourth external electrode. The electronic component element assembly comprises a plurality of internal electrodes, and has a first end surface and a second end surface on which the internal electrodes are exposed, and a side surface connecting the first end surface and the second end surface. The first external electrode covers the first end surface and does not cover the side surface. The second external electrode covers the second end surface and does not cover the side surface. The third external electrode is formed so as to cover a part of the side surface and a part of a region of the first external electrode different from the surface thereof that is in contact with the first end surface. The fourth external electrode is formed so as to cover a part of the side surface and a part of a region of the second external electrode different from the surface thereof that is in contact with the second end surface. The first external electrode and the second external electrode comprise a first metal film that does not contain a glass constituent and has pores therein. The third external electrode and the fourth external electrode comprise a second metal film that contains a glass constituent. When the first end surface and the second end surface are viewed in a plan view from the respective normal directions thereof, the area of the third external electrode covering the first external electrode and the area of the fourth external electrode covering the second external electrode are each 80% or less.

Description

Electronic component and method for manufacturing electronic component

[0001] The present invention relates to an electronic component having external electrodes on the end faces of an element body incorporating a laminate in which a plurality of elements are stacked.

[0002] Patent Document 1 describes an electrolytic capacitor. The electrolytic capacitor has a first electrode layer formed on an end surface of a capacitor element. Furthermore, a second electrode layer is formed in contact with the first electrode layer. The first electrode layer is made of, for example, copper (copper metal powder) and is formed using an aerosol deposition (AD) method. The second electrode layer is made of a conductive resin. The first and second electrode layers are formed to cover the end surfaces of the capacitor element and portions of the side surfaces connected to the end surfaces. In other words, the first and second electrode layers are formed to cover the end surfaces, portions of the side surfaces, and corners of the capacitor element.

[0003] Patent Document 2 describes a multilayer ceramic capacitor. The external electrodes of the multilayer ceramic capacitor are formed by applying a conductive paste to the end faces of the dielectric ceramic and then firing the paste. The main component of the conductive paste is copper (copper metal powder) and also contains glass frit. This improves the adhesion between the dielectric ceramic and the conductive paste.

[0004] Patent Document 3 describes a PML (Polymer Multilayer) capacitor. The capacitor element of the chip capacitor is formed by alternately laminating resin thin film layers that serve as dielectric layers and internal electrode layers. The electrodes provided on the end faces of the capacitor element include metal-containing portions formed by sputtering.

[0005] International Publication No. 2022 / 168768 Japanese Patent Application Laid-Open No. 2003-217969 Japanese Patent Application Laid-Open No. 2006-216603

[0006] Conventionally, a known way to achieve compact, high-capacity capacitors is to reduce the thickness of the external electrodes formed on the end faces of the capacitor body. However, when the external electrodes of a capacitor are formed to be thin, the external electrodes are not sufficiently formed at the corners of the capacitor body, making it easy for plating solution and water vapor in the air to penetrate. This reduces the reliability of the capacitor. Furthermore, if the external electrodes are not formed to cover the corners or part of the side surfaces of the capacitor body, mounting properties such as soldering are reduced. Various structures have been investigated to solve these problems.

[0007] In the configuration described in Patent Document 1, a second electrode layer is formed on top of a first electrode layer formed using the AD method. As described above, the first electrode is formed by spraying copper metal powder using the AD method. The second electrode is formed by applying a conductive resin so as to cover the first electrode. In other words, there is a risk that the adhesion between the first electrode layer and the second electrode layer will be reduced. As a result, the first electrode layer and the second electrode layer are prone to peeling, and plating solution, water vapor in the air, and the like will easily invade through the peeled portion.

[0008] Furthermore, in the configuration described in Patent Document 2, the dielectric ceramic reacts with the glass contained in the conductive paste, that is, a reaction layer is generated. The generation of this reaction layer may reduce the strength of the dielectric ceramic laminate.

[0009] Furthermore, in the configuration described in Patent Document 3, the external electrodes are formed by plating or sputtering to form them thin. This increases the density of the external electrodes, but reduces the bonding strength between the external electrodes and the laminate. Therefore, if a thermal shock is applied to the external electrodes, there is a risk that the external electrodes will peel off from the capacitor element due to differences in thermal expansion. Furthermore, because the external electrodes are formed by plating or sputtering, it is difficult to cover the corners and side surfaces of the capacitor element.

[0010] Therefore, an object of the present invention is to realize an electronic component that improves reliability by suppressing poor contact and the intrusion of plating solution, moisture, etc. from the outside, and also improves volumetric capacity efficiency.

[0011] The electronic component of the present invention comprises an electronic component body, a first external electrode, a second external electrode, a third external electrode, and a fourth external electrode. The electronic component body comprises a plurality of internal electrodes, and has first and second end faces from which the internal electrodes are exposed, and side faces connecting the first and second end faces. The first external electrode covers the first end face but not the side faces. The second external electrode covers the second end face but not the side faces. The third external electrode is formed so as to cover a portion of the side faces and a portion of a region of the first external electrode other than the surface abutting the first end face. The fourth external electrode is formed so as to cover a portion of the side faces and a portion of a region of the second external electrode other than the surface abutting the second end face.

[0012] The first and second external electrodes are made of a first metal film that does not contain a glass component and has pores therein. The third and fourth external electrodes are made of a second metal film that contains a glass component. When the first end face and the second end face are viewed in plan from their normal directions, the area over which the third external electrode covers the first external electrode and the area over which the fourth external electrode covers the second external electrode are each 80% or less.

[0013] In this configuration, first and second external electrodes made of glass-free electrode films are formed on the end faces of the electronic component body. Because the electrode films do not contain glass, no reactive layer that reacts with the electronic component body is formed. This means that the strength of the electronic component body is not reduced. Furthermore, because the electrode films have pores inside, peeling between the electronic component body and the external electrodes due to thermal expansion is suppressed even when thermal shock is applied. Furthermore, because the third and fourth external electrodes are formed on the side surfaces, the mountability of the electronic component is improved. Furthermore, because the third external electrode covers 80% or less of the first external electrode formed on the first end face, and the fourth external electrode covers 80% or less of the second external electrode formed on the second end face, the third and fourth external electrodes can be formed thin. This means that the dimensions of the external electrode portions of the electronic component can be suppressed, improving volumetric capacity efficiency.

[0014] A method for manufacturing an electronic component according to the present invention includes the steps of forming an electronic component body, forming a first external electrode, forming a second external electrode, forming a third external electrode, and forming a fourth external electrode. In the step of forming the electronic component body, the electronic component body is formed to have a plurality of internal electrodes, a first end face and a second end face on which the internal electrodes are exposed, and a side face connecting the first end face and the second end face. In the step of forming the first external electrode, the first external electrode is formed to cover the first end face but not the side face. In the step of forming the second external electrode, the second external electrode is formed to cover the second end face but not the side face. In the step of forming the third external electrode, the third external electrode is formed to cover a portion of the side face and a portion of a region of the first external electrode other than the surface abutting the first end face. In the step of forming the fourth external electrode, the fourth external electrode is formed to cover a portion of the side face and a portion of a region of the second external electrode other than the surface abutting the second end face.

[0015] The first and second external electrodes are formed by a first metal film that does not contain glass components and has pores formed therein by an aerosol deposition (AD) method on at least the exposed portions of the internal electrodes in the electronic component body and on the first and second end faces of the electronic component body when viewed in a plan view from the normal direction of the first and second end faces, respectively. The first and second external electrodes are formed by scraping off the first metal film so that the area covered by the third external electrode and the area covered by the fourth external electrode are 80% or less, respectively. The third and fourth external electrodes are formed by a second metal film that contains glass components.

[0016] In this method, glass-free electrode films are formed on the end faces of an electronic component body by the AD method. These electrode films are the first and second external electrodes. Because the electrode films do not contain glass, no reaction layer is formed. This means that the strength of the electronic component body is not reduced. Furthermore, because the electrode films have pores inside, peeling between the electronic component body and the electrode films due to the thermal expansion coefficient is suppressed even when thermal shock is applied. Furthermore, by forming the third and fourth external electrodes on the side surfaces, the mountability of the electronic component can be improved. Furthermore, because the third external electrode covers 80% or less of the first external electrode formed on the first end face, and the fourth external electrode covers 80% or less of the second external electrode formed on the second end face, the third and fourth external electrodes can be formed thin. This means that the dimensions of the external electrode portions of the electronic component can be suppressed, improving volumetric capacity efficiency.

[0017] According to the present invention, it is possible to realize an electronic component with improved reliability and improved volumetric capacity efficiency by suppressing poor contact and the intrusion of plating solution, moisture, etc. from the outside.

[0018] [Correction based on Rule 91 06.11.2024] FIG. 1 is an external perspective view of a multilayer ceramic capacitor according to a first embodiment of the present invention. FIG. 2 is a side cross-sectional view showing the configuration of the multilayer ceramic capacitor according to the first embodiment of the present invention. FIG. 3 is an enlarged plan view of an end face where an internal electrode is exposed in an electronic component body of the multilayer ceramic capacitor. FIG. 4(A) is a cross-sectional view of a first electrode layer according to the first embodiment of the present invention, and FIG. 4(B) is a cross-sectional view of an electrode layer in a conventional configuration. FIG. 5 is a flowchart showing an example of a general flow of a method for manufacturing a multilayer ceramic capacitor according to the first embodiment of the present invention. FIG. 6 is a flowchart showing an example of forming a first electrode layer according to the first embodiment of the present invention. FIG. 7 is a diagram showing the configuration of an electrode layer forming apparatus using the AD method. FIG. 8 is a flowchart showing an example of forming a second electrode layer according to the first embodiment of the present invention. FIGS. 9(A) to 9(I) are diagrams showing the process of forming a second electrode layer. FIG. 10 is a table showing the relationship between the structures of the first and second electrode layers. FIGS. 11(A) and 11(B) are side cross-sectional views showing the configuration of a multilayer ceramic capacitor according to a modified example of the present invention. FIG. 12 is a side cross-sectional view showing the structure of a multilayer ceramic capacitor according to a modified example of the present invention.

[0019] [First Embodiment] An electronic component and a method for manufacturing an electronic component according to a first embodiment of the present invention will be described with reference to the drawings. In each embodiment of the present invention, a multilayer ceramic capacitor will be described as an example of the electronic component. However, the configuration of this embodiment can be applied to any chip-type capacitor having external electrodes on the end surfaces of the electronic component body. For example, a chip-type capacitor has an electronic component body formed by laminating dielectric sheets. In a chip-type capacitor, a functional portion of the capacitor is formed inside the electronic component body. In a chip-type capacitor, electrodes of the functional portion of the capacitor are exposed from the end surfaces of the electronic component body, and external electrodes are formed on these exposed surfaces.

[0020] (Explanation of the Structure of Multilayer Ceramic Capacitor 10) FIG. 1 is an external perspective view of a multilayer ceramic capacitor according to a first embodiment of the present invention. FIG. 2 is a side cross-sectional view showing the structure of the multilayer ceramic capacitor according to the first embodiment of the present invention. FIG. 3 is an enlarged plan view of an end face at which an internal electrode is exposed in an electronic component body of the multilayer ceramic capacitor. FIG. 4(A) is a cross-sectional view of a first electrode layer according to the first embodiment of the present invention, and FIG. 4(B) is a cross-sectional view of an electrode layer in a conventional structure. In FIGS. 2 and 3, dimensions in each direction are appropriately exaggerated to clearly illustrate the structure, and the dimension in the height direction (z-axis direction in the drawings) is particularly emphasized. The cross-sectional views in FIGS. 2 and 3 are cross-sectional views in the XZ plane of the multilayer ceramic capacitor shown in FIG. 1.

[0021] As shown in Figures 1 and 2, the multilayer ceramic capacitor 10 includes an element body 11, first electrode layers 61 and 62, second electrode layers 71 and 72, and external electrodes 81 and 82. The first electrode layer 61 corresponds to the "first external electrode" of the present invention. The first electrode layer 62 corresponds to the "second external electrode" of the present invention. The second electrode layer 71 corresponds to the "third external electrode" of the present invention. The second electrode layer 72 corresponds to the "fourth external electrode" of the present invention. The external electrode 81 corresponds to the "fifth external electrode" of the present invention. The external electrode 82 corresponds to the "sixth external electrode" of the present invention.

[0022] The element body 11 has a rectangular parallelepiped shape and has an end face 111, an end face 112, a first side face 101, a second side face 102, a third side face 103, and a fourth side face 104. The element body 11 corresponds to an "electronic component element body" of the present invention. The end face 111 corresponds to a "first end face" of the present invention, and the end face 112 corresponds to a "second end face" of the present invention. As shown in FIG. 1 , the first side face 101 corresponds to the top face of the element body 11, and the third side face 103 corresponds to the bottom face. However, these are used for convenience of explanation, and when the multilayer ceramic capacitor 10 is mounted on a circuit board, either side may face the circuit board.

[0023] The first side surface 101 is a surface that connects to the end surface 111, the end surface 112, the second side surface 102, and the fourth side surface 104. The second side surface 102 is a surface that connects to the end surface 111, the end surface 112, the first side surface 101, and the third side surface 103. The third side surface 103 is a surface that connects to the end surface 111, the end surface 112, the second side surface 102, and the fourth side surface 104. The fourth side surface 104 is a surface that connects to the end surface 111, the end surface 112, the first side surface 101, and the third side surface 103. In the examples shown below, the first side surface 101, the second side surface 102, the third side surface 103, and the fourth side surface 104 will be collectively referred to simply as "side surfaces."

[0024] The element body 11 includes a plurality of internal electrodes 20, 30 and a multilayer ceramic layer 50. The multilayer ceramic layer 50 is formed by stacking dielectric sheets.

[0025] The internal electrode 30 is in the form of a flat film, and has a first end face, a second end face, a flat film surface on the first side surface 101 side, and a flat film surface on the third side surface 103 side. The internal electrodes 20, 30 are made of, for example, nickel.

[0026] More specifically, the element body 11 is formed as follows: First, a conductive paste for the internal electrodes is printed in a predetermined pattern on a dielectric sheet using screen printing or the like, thereby forming the internal electrode pattern (internal electrodes 20, 30).

[0027] The element body 11 is formed by alternately stacking dielectric sheets (hereinafter referred to as first sheets) on which internal electrodes 20 are formed and dielectric sheets (hereinafter referred to as second sheets) on which internal electrodes 30 are formed. As shown in Fig. 2 , the internal electrodes 20 are exposed on an end face 111, and the internal electrodes 30 are exposed on an end face 112. Dielectric sheets on which no internal electrode patterns are formed are stacked so as to be located on the top and bottom faces of the element body 11.

[0028] Next, the element body 11 is fired. Furthermore, the first electrode layer 61 is formed on the end surface 111 of the element body 11, and the first electrode layer 62 is formed on the end surface 112 of the element body 11.

[0029] Next, a second electrode layer 71 is formed so as to cover at least a portion of the first electrode layer 61 or a portion of the side surface of the element body 11. Similarly, a second electrode layer 72 is formed so as to cover at least a portion of the first electrode layer 62 or a portion of the side surface of the element body 11. A more detailed structure will be described later.

[0030] Furthermore, an external electrode 81 is formed so as to cover the first electrode layer 61 and the second electrode layer 71. An external electrode 82 is formed so as to cover the first electrode layer 62 and the second electrode layer 72. This completes the multilayer ceramic capacitor 10. The configurations of the first electrode layers 61, 62, the second electrode layers 71, 72, and the external electrodes 81, 82 will be described later.

[0031] With this configuration, the internal electrodes 20 and 30 face each other with the dielectric sheet sandwiched between them, and function as a capacitor having a predetermined capacitance.

[0032] The first sheet and the second sheet are flat membrane-shaped. The multiple first sheets and the multiple second sheets are arranged so that their respective flat membrane surfaces are approximately parallel to the top and bottom surfaces of the element body 11. As described above, the multiple first sheets and the multiple second sheets are arranged alternately in a direction perpendicular to the top and bottom surfaces (the height direction of the element body 11 (z-axis direction in the figure)). Note that in FIG. 2, the number of the multiple first sheets is three and the number of the multiple second sheets is four, but this is not limited to this.

[0033] In this stacked state, the end faces 211 (see FIG. 2 ) of the multiple first sheet internal electrodes 20 are located at approximately the same position in side view. The end faces 311 of the multiple second sheet internal electrodes 30 are located at approximately the same position in side view. The end faces 211 of the multiple first sheet internal electrodes 20 protrude beyond the end faces 312 of the multiple second sheet internal electrodes 30. The end faces 311 of the multiple second sheet internal electrodes 30 protrude beyond the end faces 212 of the multiple first sheet internal electrodes 20.

[0034] As a result, the end faces 211 of the internal electrodes 20 of the first sheet are exposed to the outside of the element body 11 from the end face 111 of the element body 11. The internal electrodes 30 of the second sheet are exposed to the outside of the element body 11 from the end face 112 of the element body 11.

[0035] The first electrode layers 61, 62 are composed of particles made of a metal material. The first electrode layers 61, 62 preferably contain at least one of copper, nickel, tin, and zinc. The first electrode layers 61, 62 do not contain glass components such as glass frit. Note that the phrase "does not contain glass frit, etc." does not include a configuration in which glass components are inevitably mixed in during the manufacturing process.

[0036] The configurations of the first electrode layer 61, the second electrode layer 71, and the external electrode 81 will be described using FIG. 3 . While the configurations of the first electrode layer 61, the second electrode layer 71, and the external electrode 81 are described in FIG. 3 , the configurations of the first electrode layer 61, the second electrode layer 71, and the external electrode 81 are similarly described. The first electrode layer 61 is formed only on the end surface 111 of the element body 11. That is, the first electrode layer 61 does not cover the side surfaces. More specifically, the first electrode layer 61 is formed on the end surfaces 211 of the multiple internal electrodes 20. The first electrode layer 61 is also formed on the entire end surface 111 of the element body 11. The first electrode layer 61 is formed to a predetermined thickness (height) from the end surface 111 of the element body 11. The thickness of the first electrode layer 61 is preferably 3 μm or more and 25 μm or less. The above-described configuration in which the first electrode layer 61 is formed only on the end surface 111 of the element body 11 does not include a configuration in which the first electrode layer 61 is unavoidably formed on the side surface during the manufacturing process.

[0037] The second electrode layer 71 is formed by firing a copper conductive paste. The second electrode layer 71 preferably contains a glass component such as glass frit, which improves the durability and heat resistance of the second electrode layer 71.

[0038] The external electrode 81 is made of an electrode film 811 and an electrode film 812, and is formed by plating. For example, the electrode film 811 is a nickel plating layer.

[0039] The thickness of the terminal electrode made up of the first electrode layer 61, the second electrode layer 71, and the external electrode 81 is preferably 8 μm or more and less than 20 μm. That is, the first electrode layer 61, the second electrode layer 71, and the external electrode 81 function as external electrodes of the multilayer ceramic capacitor 10.

[0040] The multilayer ceramic capacitor 10 is realized by the above configuration.

[0041] 3, the first electrode layers 61, 62 are metal layers (first metal films) having pores (voids) 60P. The pores 60P are formed in the first electrode layers 61, 62 at a predetermined ratio (hereinafter referred to as the pore area ratio).

[0042] More specifically, the first electrode layer 61 is formed with a predetermined pore area (void) ratio on the surface of the end face 111 of the element body 11. Similarly, the first electrode layer 62 is formed with a predetermined pore area (void) ratio on the surface of the end face 112 of the element body 11. The pore area ratio here is expressed as the ratio (percentage) of the area including the pores 60P in a cross section of the first electrode layer 61 parallel to the end face 111 of the element body 11, when the area of ​​this cross section is taken as 100. The method of calculating the pore area ratio is the same for the first electrode layer 62.

[0043] The pore area ratio is measured by exposing the end surface 111 of the element body 11 on which the first electrode layer 61 is formed in the multilayer ceramic capacitor 10 shown in FIG. 3 and then observing it with an optical microscope. More specifically, the pore area ratio can be determined by analyzing the image shown in FIG. 4(A). The area of ​​the first electrode layer 61 is calculated by binarizing the obtained image to distinguish between the first electrode layer 61 and the pores (voids) 60P where the first electrode layer 61 is not formed. As described above, the pore area ratio is calculated as the ratio of the area of ​​the pores 60P to the sum of the areas of the first electrode layer 61 and the pores (voids) 60P where the first electrode layer 61 is not formed. The pore area ratio of the first electrode layer 62 is also calculated in a similar manner.

[0044] On the other hand, the configuration shown in Fig. 4(B) shows an electrode layer of a conventional configuration. Compared to Fig. 4(A), the electrode layer of Fig. 4(B) does not have pores (voids). More specifically, in the structure of Fig. 4(A) which is the configuration of the present invention, pores 60P are formed at a predetermined ratio (pore area ratio), so that the internal electrode 20 or the internal electrode 30 is exposed. On the other hand, in Fig. 4(B) which is the conventional configuration, the internal electrode is not exposed because there are no pores 60P.

[0045] 4(A) showing the configuration of the present invention with the conventional configuration of FIG. 4(B), the pores 60P in the configuration of the present invention alleviate internal stress. This prevents stress from occurring between the first electrode layers 61, 62 and the element body 11 due to differences in thermal expansion coefficients caused by heat shock or the like. Therefore, peeling between the element body 11 and the first electrode layers 61, 62 is prevented.

[0046] A specific method for forming the first electrode layers 61 and 62 and a specific shape thereof will be described later.

[0047] 2 and 3 , the second electrode layers 71 and 72 are metal layers (second metal films) that cover part of the side surface of the element body 11. More specifically, the second electrode layers 71 and 72 are thick-film pastes that contain copper. The second electrode layers 71 and 72 can be formed more uniformly by using thick-film pastes, which improves the smoothness and adhesion of the layers when dried.

[0048] The second electrode layer 71 is formed so as to cover a portion of the side surface of the element body 11. Similarly, the second electrode layer 72 is formed so as to cover a portion of the side surface of the element body 11. The dimensions of the second electrode layers 71, 72 formed on the side surfaces of the element body 11 are preferably formed to be 50 μm or less. In the configuration shown in FIG. 3 , the second electrode layer 71 does not cover the end surface 111. In other words, the second electrode layer 71 is not formed on the end surface 111. Similarly, the second electrode layer 72 does not cover the end surface 112. In other words, the second electrode layer 72 is not formed on the end surface 112.

[0049] (Detailed configuration of external electrodes 81, 82) The external electrode 81 (electrode films 811 and 812) is formed so as to cover the first electrode layer 61 and the second electrode layer 71. The external electrode 82 (electrode films 821 and 822) is formed so as to cover the first electrode layer 62 and the second electrode layer 72.

[0050] The electrode films 811 and 812 are nickel-plated to improve corrosion resistance, strength, and ductility, while the tin-plated electrodes 811 and 812 are tin-plated to improve solderability and conductivity when the multilayer ceramic capacitor 10 is mounted.

[0051] (Method of Manufacturing Multilayer Ceramic Capacitor 10) The multilayer ceramic capacitor 10 having the above-described configuration is manufactured, for example, as follows. FIG. 5 is a flowchart showing an example of a schematic flow of a method of manufacturing a multilayer ceramic capacitor according to the first embodiment of the present invention. FIG. 6 is a flowchart showing an example of forming first electrode layers 61, 62 according to the first embodiment of the present invention. FIG. 7 is a diagram showing the configuration of an apparatus for forming electrode layers by the AD method. FIG. 8 is a flowchart showing an example of forming second electrode layers 71, 72 according to the first embodiment of the present invention.

[0052] First, an outline of a method for manufacturing a multilayer ceramic capacitor will be described using FIG. 5 . An element body 11 is formed (S11). Specifically, first sheets on which internal electrodes 20 are formed and dielectric sheets on which internal electrodes 30 are formed are alternately laminated, and dielectric sheets on which no internal electrode patterns are formed are laminated on the top and bottom surfaces of the laminate. This forms the element body 11. This process is performed in the form of a multi-substrate in which multiple element bodies 11 can be formed at once. By dividing this multi-substrate into individual element bodies 11, the internal electrodes 20 are exposed on end surfaces 111 and the internal electrodes 30 are exposed on end surfaces 112, as shown in FIG. 2 . This element body 11 is then fired.

[0053] Next, first electrode layers 61 are formed on the end faces 211 of the internal electrodes 20 of the plurality of first sheets and on the end face 111 of the element body 11. Similarly, first electrode layers 62 are formed on the end face 112 of the element body 11. The first electrode layers 61, 62 are formed using the AD method (S12). A more specific method for forming the first electrode layers 61, 62 using the AD method will be described later with reference to FIGS. 6 and 7.

[0054] Next, a second electrode layer 71 is formed so as to cover the first electrode layer 61 and a portion of the side surface of the element body 11 that is adjacent to the end face 111 (S13). Similarly, a second electrode layer 72 is formed so as to cover the first electrode layer 61 and a portion of the side surface of the element body 11 that is adjacent to the end face 112. A more specific method for forming the second electrode layers 71 and 72 will be described later with reference to FIG. 8 .

[0055] Next, the element body 11 on which the first electrode layers 61, 62 and the second electrode layers 71, 72 are formed is heated and fired (S14).

[0056] Next, external electrodes 81 and 82 are formed to cover the first electrode layers 61 and 62 and the second electrode layers 71 and 72 (S15). First, an electrode film 811 (nickel plating layer) is formed to cover the first electrode layer 61 and the second electrode layer 71. An electrode film 812 (tin plating layer) is formed to cover the electrode film 811. Similarly, an electrode film 821 (nickel plating layer) is formed to cover the first electrode layer 62 and the second electrode layer 72. An electrode film 822 (tin plating layer) that is a tin plating layer is formed to cover the electrode film 821.

[0057] As a result, the first electrode layers 61 and 62 , the second electrode layers 71 and 72 , and the external electrodes 81 and 82 function as external electrodes of the multilayer ceramic capacitor 10 .

[0058] (Method of forming first electrode layers 61, 62) Next, a method of forming the first electrode layers 61, 62 will be described with reference to Figures 6 and 7. Figure 6 is a flowchart showing an example of forming the first electrode layers 61, 62 according to the first embodiment of the present invention. Figure 7 is a diagram showing the configuration of an apparatus for forming an electrode layer by the AD method.

[0059] The first electrode layer 61 is formed on the end surface 111 of the element body 11 and the end surfaces 211 of the internal electrodes 20 of the first sheets using the AD method (S21).

[0060] 7 , a plurality of element bodies 11 are fixed on a stage 902 and placed in a chamber 901. At least the tip (ejection end) of an aerosol generator 903 is inserted into the chamber 901. The aerosol generator 903 generates an aerosol by introducing copper powder 600 into a carrier gas, and sprays the aerosol onto the end faces 111 of the element bodies 11.

[0061] At this time, by appropriately setting the aerosol specifications (e.g., the volume ratio of copper powder 600 contained in the carrier gas) and the spraying conditions (e.g., the number of sprays, the spraying strength, etc.), the copper powder 600 is struck against the end surface 111 of the base body 11 and piled up to a predetermined height (predetermined thickness).

[0062] As a result, the first electrode layer 61 is formed on the end surface 111 of the element body 11 and the end surface 211 of the internal electrode 20 of the first sheet (see FIGS. 2 and 3). The end surface 211 corresponds to the "exposed portion" of the present invention. In this case, the particle size of the copper powder 600 is, for example, about 3 μm, but may be 2 μm or less.

[0063] By using the AD method, pores 60P are formed when the first electrode layer 61 is formed. The pore area ratio when the pores 60P are formed varies depending on the spraying conditions using the AD method. The pore area ratio is determined according to the film formation rate, film formation time, etc.

[0064] Next, first electrode layers 62 are formed on the end faces 112 of the element body 11 and the end faces 311 of the internal electrodes 30 of the second sheets using the AD method (S22). The method for forming the first electrode layers 62 is the same as the method for forming the first electrode layers 61 in step S21 described above, and therefore a description thereof will be omitted.

[0065] In this way, the first electrode layers 61 and 62 are formed using the AD method. That is, the first electrode layers 61 and 62 are thin and have a dense structure, which makes it possible to prevent the intrusion of plating solution, moisture, and the like.

[0066] (Method of forming second electrode layers 71, 72) Next, an outline of a method of forming the second electrode layers 71, 72 will be described with reference to Fig. 8 and Figs. 9(A) to 9(H). Fig. 8 is a flowchart showing an example of forming the second electrode layers 71, 72. Figs. 9(A) to 9(H) are views showing the steps of forming the second electrode layers 71, 72.

[0067] 9A, the end surface 111 of the element body 11 is fixed to a jig 911 (S31). At this time, the element body 11 is fixed so that the height is approximately uniform and so that the element body 11 stands upright. "Upright" means that the side surface of the element body 11 is perpendicular to the surface of the jig 911 with which the element body 11 abuts.

[0068] Next, as shown in FIG. 9B , the end surface 112 of the element body 11 is pressed against a first holder 912 to fix it (S32). The first holder 912 is made of an elastic material such as silicone rubber. The first holder 912 includes a holding plate 912a and an adhesive plate 912b. At this time, the end surface 112 of the element body 11 is pressed against the adhesive plate 912b. Next, the jig 911 is removed, and the element body 11 is fixed to the first holder 912. Therefore, the element body 11 stands upright so that the end surface 111 is exposed.

[0069] 9C, the end surface 111 is immersed in a conductive paste bath 913 containing a conductive paste. As a result, the conductive paste is applied to the end surface 111 and the side surface (S33). The applied conductive paste is then dried.

[0070] Next, as shown in FIG. 9(D), the dried conductive paste is pressed against the adhesive plate 926 of the second holder 925. The adhesive plate 926 of this second holder 925 has strong adhesive strength. Therefore, the conductive paste applied to the end surface 111 of the element body 11 is scraped off by the adhesive plate 926 (S34). As a result, only the first electrode layer 61 remains on the end surface 111 of the element body 11. In other words, the area of ​​the second electrode layer 71 covering the first electrode layer 61 on the end surface of the element body 11 is 0%. Meanwhile, the second electrode layer 71 is formed on a portion of the side surface that is connected to the end surface 111 of the element body 11 (the second electrode layer 71 remains).

[0071] 9(E), the end surface 112 of the element body 11 is fixed to a jig 911 (S35). At this time, the element body 11 is fixed so that the height is approximately uniform and the element body 11 stands upright.

[0072] Next, as shown in Fig. 9(F), the end surface 111 of the element body 11 is pressed against the first holder 912 to fix it (S36). Next, the jig 911 is removed, and the element body 11 is fixed to the first holder 912. As shown in Fig. 9(G), the element body 11 stands upright so that the end surface 112 is exposed.

[0073] 9(G), the end face 111 is immersed in a conductive paste bath 913 containing a conductive paste. As a result, the conductive paste is applied to the end face 112 and the side surface of the element body 11 adjacent to the end face 112 (S37). The applied conductive paste is then dried.

[0074] Next, as shown in FIG. 9(H), the dried conductive paste is pressed against the adhesive plate 926 of the second holder 925. The adhesive plate 926 of this second holder 925 has strong adhesive strength. Therefore, the conductive paste applied to the end surface 112 of the element body 11 is scraped off by the adhesive plate 926 (S38). As a result, only the first electrode layer 62 remains on the end surface 112 of the element body 11. In other words, the area of ​​the second electrode layer 72 covering the first electrode layer 62 on the end surface of the element body 11 is 0%. Meanwhile, the second electrode layer 72 is formed on the side surface of the element body 11 that is connected to the end surface 112 (the second electrode layer 72 remains). Next, as shown in FIG. 9(I), the element body 11 is removed.

[0075] By using such a manufacturing method, a second electrode layer 71 is formed on a part of the side surface that is connected to the end surface 111 of the element body 11. Similarly, a second electrode layer 72 is formed on a part of the side surface that is connected to the end surface 112 of the element body 11.

[0076] By using the manufacturing method described above, the multilayer ceramic capacitor 10 having the above-described configuration can be manufactured easily and more reliably.

[0077] The first external electrodes of the multilayer ceramic capacitor 10 are realized by forming the first electrode layers 61, 62 using the AD method. That is, the first external electrodes can be formed by a simple method.

[0078] Furthermore, the first electrode layers 61, 62 do not contain glass components. That is, no reaction layer is formed between the multilayer ceramic layer 50 and the first electrode layers 61, 62. This prevents a decrease in the strength of the multilayer ceramic capacitor 10. Furthermore, since the first electrode layers 61, 62 do not contain glass components, it is possible to prevent the penetration of plating solution, moisture, and the like into the interior. This improves the reliability of the multilayer ceramic capacitor 10.

[0079] The second external electrodes of the multilayer ceramic capacitor 10 are realized by forming second electrode layers 71 and 72. The second electrode layer 71 is formed on a part of the side surface that is connected to the end surface 111 of the element body 11. The second electrode layer 72 is formed on a part of the side surface that is connected to the end surface 112 of the element body 11.

[0080] The external electrode 81 is shaped to cover the first electrode layer 61 and the second electrode layer 71, and the external electrode 82 is shaped to cover the first electrode layer 62 and the second electrode layer 72. Therefore, the external electrodes of the multilayer ceramic capacitor 10 cover the end faces of the element body, the corners where the end faces intersect with the side faces, and part of the side faces extending a predetermined length from the corners. This improves the mountability of the multilayer ceramic capacitor 10.

[0081] Furthermore, as shown in step S34 of FIG. 8 (FIG. 9(D)), by scraping off the second electrode layer 71, only the first electrode layer 61 remains on the end surface 111. Similarly, as shown in step S38 of FIG. 8 (FIG. 9(H)), by scraping off the second electrode layer 72, only the first electrode layer 62 remains on the end surface 112. This allows the thickness of the electrode layers formed on the end surfaces 111 and 112 to be reduced. In other words, the volumetric capacitance efficiency is improved. The volumetric capacitance efficiency indicates how much capacitance can be obtained relative to the volume of the multilayer ceramic capacitor 10; the greater the capacitance obtained relative to the volume, the higher the volumetric capacitance efficiency.

[0082] In the above-described configuration, the external electrodes 81 and 82 are provided. However, the external electrodes of the multilayer ceramic capacitor 10 may be formed by using only the first electrode layers 61 and 62 and the second electrode layers 71 and 72. However, by providing the external electrodes 81 and 82, it is possible to more efficiently prevent the intrusion of plating solution, water vapor in the air, and the like from the outside.

[0083] (Relationship between First Electrode Layer and Second Electrode Layer) The relationship between the first electrode layers 61, 62 and the second electrode layers 71, 72 is shown using Fig. 10. Note that covering the side surfaces in Fig. 10 refers to a state in which the second electrode layer 71 is formed on a portion of the side surface that is adjacent to the end surface 111 of the element body 11, and the second electrode layer 72 is formed on a portion of the side surface that is adjacent to the end surface 112 of the element body 11.

[0084] (Pattern 1) Pattern 1 shows the structure of the first embodiment. The first electrode layers 61, 62 do not contain glass components. The second electrode layers 71, 72 contain glass components. The side surfaces are covered with the second electrode layers 71, 72. In this case, the presence of the first electrode layers 61, 62, which do not contain glass components, reduces the reduction in strength of the multilayer ceramic capacitor 10. The presence of the second electrode layers 71, 72 makes it possible to suppress the intrusion of plating solution and water vapor in the air from corners, etc. Furthermore, the formation of the second electrode layers 71, 72 on the side surfaces (side surface covering) improves the mountability of the multilayer ceramic capacitor 10.

[0085] (Pattern 2) Pattern 2 differs from the structure of Pattern 1 (first embodiment) in that the second electrode layers 71, 72 do not contain glass components. The first electrode layers 61, 62 and the second electrode layers 71, 72 do not contain glass components. Portions of the side surfaces are covered by the second electrode layers 71, 72. The presence of the first electrode layers 61, 62 reduces the strength of the multilayer ceramic capacitor 10. The presence of the second electrode layers 71, 72 also prevents plating solution and water vapor in the air from penetrating through corners, etc. However, the presence of the second electrode layers 71, 72 on the side surfaces improves the mountability of the multilayer ceramic capacitor 10.

[0086] (Pattern 3) Pattern 3 differs from the structure of Pattern 1 (first embodiment) in that the first electrode layers 61, 62 contain a glass component. The first electrode layers 61, 62 contain a glass component. This resulted in a decrease in the strength of the multilayer ceramic capacitor 10. As with Pattern 1, the inclusion of the second electrode layers 71, 72 suppressed water vapor and other contaminants in the air that could infiltrate through corners and the like. On the other hand, the formation of the second electrode layers 71, 72 on the side surfaces improved the mountability of the multilayer ceramic capacitor 10.

[0087] (Pattern 4) Pattern 4 differs from the structure of Pattern 1 (first embodiment) in that the first electrode layers 61, 62 contain a glass component, but the second electrode layer does not. The first electrode layers 61, 62 contain a glass component. This resulted in a decrease in the strength of the multilayer ceramic capacitor 10. On the other hand, the inclusion of the second electrode layers 71, 72 prevented the plating solution and water vapor in the air from penetrating through corners, etc. However, the configuration of Pattern 4 is inferior to that of Pattern 1. On the other hand, the formation of the second electrode layers 71, 72 on the side surfaces improves the mountability of the multilayer ceramic capacitor 10.

[0088] In the configurations of the above-described patterns 1 to 4, if the second electrode layers 71 and 72 are not formed on the side surfaces, the mountability will be reduced. Furthermore, there is a high possibility that the reliability will also be reduced.

[0089] [Modification] A multilayer ceramic capacitor according to a modification of the present invention will be described with reference to the drawings. The multilayer ceramic capacitor according to the modification differs from the multilayer ceramic capacitor 10 according to the first embodiment in that a second electrode layer 71 is formed on an end face 111 and a second electrode layer 72 is formed on an end face 112. The other configurations of the ceramic capacitor according to the modification are the same as those of the multilayer ceramic capacitor according to the first embodiment, and a description of similar parts will be omitted.

[0090] 11A and 11B are side cross-sectional views showing the configuration of a multilayer ceramic capacitor according to a modified example of the present invention, and Fig. 12 is a side cross-sectional view showing the configuration of a multilayer ceramic capacitor according to a modified example of the present invention.

[0091] 11A , a second electrode layer 71 is formed so as to cover the first electrode layer 61 formed on an end surface 111. When the end surface 111 is flattened, the proportion of the area of ​​the second electrode layer 71 covering the first electrode layer 61 is approximately 20%. Similarly, a second electrode layer 72 is formed so as to cover the first electrode layer 62 formed on an end surface 112. When the end surface 112 is flattened, the proportion of the area of ​​the second electrode layer 72 covering the first electrode layer 62 is approximately 20%.

[0092] The area ratio is calculated as a ratio of the area where the second electrode layer 71 is formed when the end face 111 is viewed in a plan view from the normal direction. It is calculated as the ratio of the area of ​​the portion where the second electrode layer 71 is formed to the sum of the area of ​​the portion where the second electrode layer 71 is formed and the area of ​​the portion where the second electrode layer 71 is not formed with respect to the first electrode layer 61. The area ratio of the end face 112 is calculated in a similar manner.

[0093] 11B , the second electrode layer 71 is formed so as to cover the first electrode layer 61 formed on the end surface 111. When the end surface 111 is flattened, the proportion of the area of ​​the second electrode layer 71 covering the first electrode layer 61 is approximately 30%. Similarly, the second electrode layer 72 is formed so as to cover the first electrode layer 62 formed on the end surface 112. When the end surface 112 is flattened, the proportion of the area of ​​the second electrode layer 72 covering the first electrode layer 62 is approximately 30%.

[0094] 12 , the second electrode layer 71 is formed so as to cover the first electrode layer 61 formed on the end surface 111. When the end surface 111 is flattened, the proportion of the area of ​​the second electrode layer 71 covering the first electrode layer 61 is approximately 70%. Similarly, the second electrode layer 72 is formed so as to cover the first electrode layer 62 formed on the end surface 112. When the end surface 112 is flattened, the proportion of the area of ​​the second electrode layer 72 covering the first electrode layer 62 is approximately 70%.

[0095] 11(A), 11(B), and 12, the second electrode layer 71 may be formed so as to cover the first electrode layer 61 on the end surface 111. Similarly, the second electrode layer 72 may be formed so as to cover the first electrode layer 62 on the end surface 111. In this case, the ratio of the area of ​​the second electrode layer 71 that covers the first electrode layer 61 and the ratio of the area of ​​the second electrode layer 72 that covers the first electrode layer 62 are preferably about 80% or less.

[0096] 11(A), 11(B), and 12, in a structure in which the second electrode layer 71 is formed so as to partially cover the first electrode layer 61, the thickness of the second electrode layer 71 and the proportion of the area of ​​the second electrode layer 71 that covers the first electrode layer 61 can be easily controlled by the viscosity and shape of the adhesive plate 926 in step S34 of FIG. 8 (FIG. 9(D)) in the first embodiment. Similarly, in a structure in which the second electrode layer 72 is formed so as to partially cover the first electrode layer 62, the thickness of the second electrode layer 72 and the proportion of the area of ​​the second electrode layer 72 that covers the first electrode layer 62 can be easily controlled by the viscosity and shape of the adhesive plate 926 in step S38 of FIG. 8 (FIG. 9(H)) in the first embodiment.

[0097] This allows the external electrodes to be formed without increasing the thickness (total thickness of the first electrode layer 61, the second electrode layer 71, and the external electrode 81) of the external electrodes formed on the end faces 111 of the element body 11. Similarly, the external electrodes can be formed without increasing the thickness (total thickness of the first electrode layer 62, the second electrode layer 72, and the external electrode 82) of the external electrodes formed on the end faces 112 of the element body 11. In other words, the volumetric capacitance efficiency of the multilayer ceramic capacitor 10 is improved.

[0098] Furthermore, since the second electrode layer 71 is in close contact with at least the end face of the first electrode layer 61, the bonding strength between the first electrode layer 61 and the second electrode layer 71 is improved. Similarly, since the second electrode layer 72 is in close contact with at least the end face of the first electrode layer 62, the bonding strength between the first electrode layer 62 and the second electrode layer 72 is improved.

[0099] In the above-described first embodiment and modified example, the second electrode layers 71 and 72 formed to cover the first electrode layers 61 and 62 have the same area ratio. However, they do not have to be the same. However, when considering the structural balance and electrical characteristics of the multilayer ceramic capacitor 10, it is preferable that the area ratios be approximately the same between the end faces 111 and 112.

[0100] DESCRIPTION OF SYMBOLS 10... Multilayer ceramic capacitor 11... Element body 20, 30... Internal electrode 50... Multilayer ceramic layer 60P... Pore 61, 62... First electrode layer 71, 72... Second electrode layer 81, 82... External electrode 101... First side 102... Second side 103... Third side 104... Fourth side 111, 112, 211, 212, 311, 312... End surface 600... Copper powder 811, 812, 821, 822... Electrode film 901... Chamber 902... Stage 903... Aerosol generator 911... Jig 912... First holder 912a... Holding plate 912b... Adhesive plate 913... Conductive paste tank 925... Second holder 926... Adhesive plate

Claims

1. An electronic component body comprising a plurality of internal electrodes, the electronic component body having a first end face and a second end face on which the internal electrodes are exposed, and a side face connecting the first end face and the second end face; a first external electrode covering the first end face but not the side face; a second external electrode covering the second end face but not the side face; a third external electrode formed to cover a portion of the side face and a portion of an area of ​​the first external electrode different from the surface of the first external electrode that abuts the first end face; and a fourth external electrode formed to cover a portion of the side face and a portion of an area of ​​the second external electrode different from the surface of the second external electrode that abuts the second end face, the first external electrode and the second external electrode being made of a first metal film that does not contain a glass component and has pores therein; the third external electrode and the fourth external electrode being made of a second metal film that contains a glass component, an area where the third external electrode covers the first external electrode and an area where the fourth external electrode covers the second external electrode are each 80% or less when the first end face and the second end face are viewed in a plan view from their respective normal directions.

2. The electronic component according to claim 1, further comprising a fifth external electrode covering said third external electrode and a sixth external electrode covering said fourth external electrode, said fifth external electrode and sixth external electrode being formed by plating.

3. The electronic component according to claim 1, wherein the first external electrode and the second external electrode have a thickness of 3 μm or more and 25 μm or less.

4. The electronic component according to claim 1 or 2, wherein the third external electrode and the fourth external electrode are formed by firing copper.

5. A method for manufacturing an electronic component body comprising the steps of: forming an electronic component body having a plurality of internal electrodes, the electronic component body having a first end face and a second end face on which the internal electrodes are exposed, and a side face connecting the first end face and the second end face; forming a first external electrode covering the first end face but not the side face; forming a second external electrode covering the second end face but not the side face; forming a third external electrode formed to cover a portion of the side face and a portion of an area of ​​the first external electrode different from the surface abutting the first end face; and forming a fourth external electrode formed to cover a portion of the side face and a portion of an area of ​​the second external electrode different from the surface abutting the second end face, the first external electrode and the second external electrode having AD (Aerosol) on at least the exposed portions of the internal electrodes in the electronic component body and the first end face and the second end face of the electronic component body when viewed in a plan view from the normal directions of the first end face and the second end face, respectively. the third external electrode and the fourth external electrode are formed of a second metal film containing a glass component, the first metal film having pores therein, the first metal film being formed by a deposition method, and the third external electrode and the fourth external electrode are formed by scraping off the first metal film so that an area of ​​the third external electrode covering the first external electrode and an area of ​​the fourth external electrode covering the second external electrode are each 80% or less, 6. A method for manufacturing an electronic component according to claim 5, further comprising the step of forming a fifth external electrode covering said third external electrode and a sixth external electrode covering said fourth external electrode by plating.

7. A method for manufacturing an electronic component according to claim 5 or 6, wherein the third external electrode and the fourth external electrode are formed by firing copper.

Images