Electronic component and method for manufacturing electronic component

Abstract

The electronic component includes an electronic component body and a first external electrode. The electronic component body includes a plurality of internal electrodes. The first external electrode includes a metal film that does not include a glass component and has pores therein. The electronic component body has a first end surface and a second end surface exposing the internal electrodes. The first external electrode is formed at least on the exposed portion of the internal electrode, the first end face and the second end face. The area ratio of pores in a cross-section of the metal film is 3% or more and less than 25%.

Description

Technical Field

[0001] The present invention relates to an electronic component including external electrodes on end surfaces of a main body having a built-in laminated body in which a plurality of elements are stacked. Background Art

[0002] Patent Document 1 describes an electrolytic capacitor. The electrolytic capacitor has a first electrode layer formed on the end face of the capacitor element. Furthermore, a second electrode layer is formed so as to abut against the first electrode layer. The first electrode layer, for example, comprises copper (Cu metal powder) and is formed using an aerosol deposition (AD) method. The second electrode layer is a conductive resin.

[0003] Patent Document 2 describes a multilayer ceramic capacitor. External electrodes of the multilayer ceramic capacitor are formed by applying a conductive paste to the end faces of a dielectric ceramic and firing the paste. The conductive paste is primarily composed of copper (Cu metal powder) and contains glass frit.

[0004] Patent Document 3 describes a PML (Polymer Multilayer) capacitor. The capacitor element of this chip capacitor is formed by alternating layers of resin film layers (which 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] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2022 / 168768

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2003-217969

[0009] Patent Document 3: Japanese Patent Application Laid-Open No. 2006-216603 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] However, in the structure described in Patent Document 1, a second electrode layer is formed above the first electrode layer formed using the AD method. This means that multiple steps are required to form the external electrodes. Consequently, the number of steps required to form the external electrodes may increase.

[0012] Furthermore, in the structure described in Patent Document 2, the dielectric ceramic reacts with the glass contained in the conductive paste, forming a reaction layer. This reaction layer may reduce the strength of the dielectric ceramic laminate.

[0013] Furthermore, in the structure described in Patent Document 3, the external electrodes are formed by plating or sputtering. This means that the density of the external electrodes is high, making it difficult to form voids. Therefore, if a thermal shock is applied to the external electrodes, the external electrodes may peel off from the capacitor element due to differences in thermal expansion.

[0014] Therefore, an object of the present invention is to realize an electronic component having a simplified process and high reliability.

[0015] Technical solutions to solve problems

[0016] An electronic component according to the present invention includes an electronic component body and a first external electrode. The electronic component body includes a plurality of internal electrodes. The first external electrode comprises a metal film that does not contain a glass component and has pores therein. The electronic component body includes a first end face and a second end face where the internal electrodes are exposed. The first external electrode is formed at least on the exposed portion of the internal electrode and on the first and second end faces. The porosity area ratio in the cross-section of the metal film is greater than or equal to 3% and less than 25%.

[0017] In this structure, external electrodes comprising a non-glass-containing electrode film are formed on the end faces of the electronic component body. Since this electrode film contains no glass, no reactive layer forms. This means the strength of the component stack is not reduced. Furthermore, because the electrode film has internal pores, even under thermal shock, separation between the component stack and the external electrode due to thermal expansion is suppressed.

[0018] The electronic component manufacturing method of the present invention comprises the following steps: forming an electronic component body having a plurality of internal electrodes; and forming first external electrodes on at least the exposed portions of the internal electrodes and the first and second end faces of the electronic component body by aerosol deposition (AD). The first external electrodes comprise a metal film that does not contain a glass component and has pores therein. The porosity area ratio in a cross-section of the metal film is 3% or more and less than 25%.

[0019] In this method, a glass-free electrode film is formed on the end face of the electronic component body using the AD method. This electrode film serves as the external electrode. Because the electrode film contains no glass, no reactive layer forms. This means the strength of the laminate is not reduced. Furthermore, because the electrode film has internal pores, even under thermal shock, separation caused by the thermal expansion coefficient between the electronic component body and the electrode film is suppressed. Furthermore, the external electrodes can be formed solely using the AD method, simplifying the process.

[0020] Effects of the Invention

[0021] According to the present invention, it is possible to realize an electronic component having simplified processes and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a perspective view of the appearance of a multilayer ceramic capacitor according to the first embodiment of the present invention.

[0023] Figure 2 It is a side cross-sectional view showing the structure of a multilayer ceramic capacitor according to the first embodiment of the present invention.

[0024] Figure 3 This is an enlarged plan view of an end surface of a multilayer ceramic capacitor where internal electrodes in an electronic component body are exposed.

[0025] Figure 4 (A) is a cross-sectional view of an electrode layer according to the first embodiment of the present invention. Figure 4 (B) is a cross-sectional view of the electrode layer in the conventional structure.

[0026] Figure 5 This is a flowchart showing an example of a schematic flow of a method for manufacturing a multilayer ceramic capacitor according to the first embodiment of the present invention.

[0027] Figure 6 It is a diagram showing the structure of an apparatus for forming an electrode layer by the AD method.

[0028] Figure 7 This is a table showing the correlation between the void area ratio, mechanical strength, and sealing performance.

[0029] Figure 8 It is a side cross-sectional view showing the structure of a multilayer ceramic capacitor according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0030] [First embodiment]

[0031] The electronic component and the method for manufacturing the electronic component according to the first embodiment of the present invention will be described with reference to the accompanying drawings. It should be noted that in each embodiment of the present invention, a stacked ceramic capacitor is used as an example of an electronic component, but the structure of this embodiment can be applied to any chip capacitor having an external electrode on the end face of the electronic component body. For example, a chip capacitor has an electronic component body formed by stacking dielectric sheets. The chip capacitor forms a functional portion of a capacitor inside the electronic component body. In the chip capacitor, the electrode of the functional portion of the capacitor is exposed from the end face of the electronic component body, and has an external electrode formed on the exposed surface.

[0032] (Description of the Structure of Multilayer Ceramic Capacitor 10)

[0033] Figure 1 It is a perspective view of the appearance of a multilayer ceramic capacitor according to the first embodiment of the present invention. Figure 2It is a side cross-sectional view showing the structure of a multilayer ceramic capacitor according to the first embodiment of the present invention. Figure 3 This is an enlarged plan view of an end surface of a multilayer ceramic capacitor where internal electrodes in an electronic component body are exposed. Figure 4 (A) is a cross-sectional view of an electrode layer according to the first embodiment of the present invention. Figure 4 (B) is a cross-sectional view of the electrode layer in the existing structure. Figure 2 、 Figure 3 In order to describe the structure in an easily understandable manner, the dimensions in various directions are appropriately emphasized, and in particular, the dimension in the height direction (z-axis direction in the drawing) is emphasized.

[0034] like Figure 1 、 Figure 2 As shown, the multilayer ceramic capacitor 10 includes a body 11 , an electrode layer 61 , and an electrode layer 62 .

[0035] The body 11 is a rectangular parallelepiped having a top, a bottom, an end face 111, an end face 112, and two side faces. The body 11 corresponds to the "electronic component body" of the present invention. The end face 111 corresponds to the "first end face" of the present invention, and the end face 112 corresponds to the "second end face" of the present invention. It should be noted that the terms "top face" and "bottom face" are used for convenience of description; when the multilayer ceramic capacitor 10 is mounted on a circuit board, either face can face the circuit board.

[0036] The main body 11 includes a plurality of internal electrodes 20 and 30 and a multilayer ceramic layer 50. The multilayer ceramic layer 50 is formed by stacking dielectric sheets.

[0037] The internal electrode 30 is in a flat film shape and has a first end surface, a second end surface, a flat film surface on the top side, and a flat film surface on the bottom side. The internal electrodes 20 and 30 are made of, for example, nickel (Ni).

[0038] More specifically, the main body 11 is formed as follows: First, a conductive paste for internal electrodes is printed on a dielectric sheet in a predetermined pattern using screen printing or the like, thereby forming an internal electrode pattern (internal electrodes 20 and 30 ).

[0039] The main body 11 is formed by alternately stacking dielectric sheets (hereinafter referred to as first sheets) on which the internal electrodes 20 are formed and dielectric sheets (hereinafter referred to as second sheets) on which the internal electrodes 30 are formed. Figure 2 As shown, the internal electrode 20 is exposed at the end surface 111, and the internal electrode 30 is exposed at the end surface 112. It should be noted that dielectric sheets without internal electrode patterns are stacked so as to be located on the top and bottom surfaces of the body 11.

[0040] Next, the main body 11 is fired. Furthermore, an electrode layer 61 serving as an external electrode is formed on the end surface 111 of the main body 11, and an electrode layer 62 serving as an external electrode is formed on the end surface 112 of the main body 11, thereby completing a multilayer ceramic capacitor. Electrode layers 61 and 62 correspond to the "first external electrodes" in the present invention. The structures of electrode layers 61 and 62 are described below.

[0041] With such a structure, the internal electrodes 20 and 30 face each other with the dielectric sheet interposed therebetween, and function as a capacitor having a predetermined capacitance.

[0042] The first sheet and the second sheet are in the shape of a flat film. The plurality of first sheets and the plurality of second sheets are arranged so that their respective flat film surfaces are approximately parallel to the top and bottom surfaces of the body 11. As described above, the plurality of first sheets and the plurality of second sheets are alternately arranged in a direction orthogonal to the top and bottom surfaces (the height direction of the body 11 (the z-axis direction in the figure)). It should be noted that Figure 2 In the embodiment, the number of the plurality of first pieces is 3, and the number of the plurality of second pieces is 4, but is not limited thereto.

[0043] In such a stacked state, the end faces 211 (see Figure 2 ) are positioned approximately in the same position when viewed from the side. The end faces 311 of the plurality of second-sheet internal electrodes 30 are positioned approximately in the same position when viewed from the side. Furthermore, the end faces 211 of the plurality of first-sheet internal electrodes 20 protrude beyond the end faces 312 of the plurality of second-sheet internal electrodes 30. Furthermore, the end faces 311 of the plurality of second-sheet internal electrodes 30 protrude beyond the end faces 212 of the plurality of first-sheet internal electrodes 20.

[0044] Thus, the end faces 211 of the first plurality of internal electrodes 20 are exposed from the end face 111 of the body 11 to the outside. In addition, the second plurality of internal electrodes 30 are exposed from the end face 112 of the body 11 to the outside.

[0045] From the perspective of conductivity and formation methods described below, electrode layers 61 and 62 are composed of particles comprising a metal material. Electrode layers 61 and 62 preferably comprise at least one of copper, nickel, tin, and zinc. Electrode layers 61 and 62 do not contain glass frit, etc., which is a glass component. It should be noted that the term "containing no glass frit, etc." does not include structures in which glass components are inevitably mixed during the manufacturing process.

[0046] like Figure 3As shown, electrode layer 61 is formed on end surface 111 of body 11. More specifically, electrode layer 61 is formed on end surfaces 211 of multiple internal electrodes 20. Furthermore, electrode layer 61 is formed over the entire end surface 111 of body 11. Electrode layer 61 is formed to a predetermined thickness (height) from end surface 111 of body 11. The thickness of electrode layer 61 is preferably 3 μm or more and 25 μm or less. In other words, electrode layer 61 functions as an external electrode of multilayer ceramic capacitor 10.

[0047] The electrode layer 62 is formed on the end surface 112 of the body 11. More specifically, the electrode layer 62 is formed on the end surfaces 311 of the plurality of internal electrodes 30. Furthermore, the electrode layer 62 is formed entirely over the end surface 112 of the body 11. The electrode layer 62 is formed to a predetermined thickness (height) from the end surface 112 of the body 11. The thickness of the electrode layer 62 is preferably between 3 μm and 25 μm. In other words, the electrode layer 62 functions as an external electrode of the multilayer ceramic capacitor 10, similarly to the electrode layer 61.

[0048] With the above-described structure, the multilayer ceramic capacitor 10 is realized.

[0049] (Detailed Structure of Electrode Layers 61 and 62)

[0050] like Figure 3 As shown, the electrode layers 61 and 62 are metal films having pores (voids) 60P. The pores 60P are formed in the electrode layers 61 and 62 at a predetermined ratio (hereinafter referred to as pore area ratio).

[0051] More specifically, the electrode layer 61 is formed on the surface of the end face 111 of the body 11 at a predetermined pore area (void) ratio. Similarly, the electrode layer 62 is formed on the surface of the end face 112 of the body 11 at a predetermined pore area (void) ratio. The pore area ratio is determined by the cross section of the electrode layer 61 parallel to the end face 111 of the body 11 ( Figure 1 The ratio (percentage) of the area including the pores 60P when the area of ​​the cross section is set to 100 in the YZ plane (in FIG. 1 ) is expressed. The calculation method of the pore area ratio is the same for the electrode layer 62.

[0052] It should be noted that for the porosity area ratio, Figure 3 In the multilayer ceramic capacitor 10 shown in FIG. 1 , the end surface 111 of the body 11 on which the electrode layer 61 is formed is exposed and then observed using an optical microscope. More specifically, the porosity area ratio can be determined by Figure 4The area ratio of the electrode layer 61 is calculated by analyzing the image shown in (A). The resulting image is binarized to distinguish the two, and the area ratio of the electrode layer 61 portion is calculated. As described above, the porosity area ratio is calculated as the ratio of the area of ​​the pores 60P portion to the sum of the areas of the electrode layer 61 and the pores (voids) 60P portion where the electrode layer 61 is not formed. The porosity area ratio of the electrode layer 62 is also calculated using the same method.

[0053] on the other hand, Figure 4 The structure shown in (B) shows the electrode layer of the conventional structure. Figure 4 Compared with (A), Figure 4 The electrode layer (B) does not form pores (voids). More specifically, in the structure of the present invention, Figure 4 In the structure of (A), the pores 60P are formed at a predetermined ratio (pore area ratio), so that the internal electrode 20 or the internal electrode 30 is exposed. Figure 4 In (B), there is no void 60P, and therefore the internal electrodes are not exposed.

[0054] That is, when compared with the structure of the present invention Figure 4 (A) with existing structure Figure 4 In the case of (B), the structure of the present invention has pores 60P, which alleviates internal stress. Specifically, stress caused by differences in thermal expansion coefficients between the electrode layers 61 and 62 and the body 11 due to thermal shock, etc., can be suppressed. Consequently, separation between the body 11 and the electrode layers 61 and 62 can be suppressed.

[0055] The specific formation method and specific shapes of the electrode layers 61 and 62 will be described later.

[0056] (Method for Manufacturing Multilayer Ceramic Capacitor 10)

[0057] The multilayer ceramic capacitor 10 having the above-described structure is manufactured, for example, as follows. Figure 5 This is a flowchart showing an example of a schematic flow of a method for manufacturing a multilayer ceramic capacitor according to the present embodiment. Figure 6 This is a diagram of an apparatus for forming electrode layers 61 and 62 by the AD method.

[0058] The main body 11 is formed (S11). Specifically, the first sheet with the internal electrode 20 formed thereon and the dielectric sheet with the internal electrode 30 formed thereon are alternately stacked, and dielectric sheets without internal electrode patterns are stacked on the top and bottom surfaces of the stacked body. In this way, the main body 11 is formed. This process is performed on a multi-substrate state in which a plurality of main bodies 11 can be formed at once. By singulating the multi-substrate for each main body 11, as shown in FIG. Figure 2As shown, the internal electrode 20 is exposed at the end surface 111, and the internal electrode 30 is exposed at the end surface 112. The body 11 is fired.

[0059] Next, electrode layer 61 is formed on end surfaces 211 of the plurality of first internal electrodes 20 and end surface 111 of body 11 . Electrode layer 61 is formed using an AD method ( S12 ). Electrode layer 61 functions as an external electrode of multilayer ceramic capacitor 10 .

[0060] More specifically, if Figure 6 As shown, multiple bodies 11 are fixed to a workbench 92 and arranged in a chamber 91. At least the front end (discharge end) of an aerosol generator 93 is inserted into the chamber 91. Aerosol generator 93 generates aerosol by introducing copper powder (Cu powder) 600 into a transport gas, and then blows the aerosol onto the end surface 111 of the body 11.

[0061] At this time, by appropriately setting the specifications of the aerosol (for example, the volume ratio of the copper powder 600 contained in the conveying gas, etc.) and the blowing conditions (for example, the number of blowing times, the blowing intensity, etc.), the copper powder 600 is impacted onto the end surface 111 of the main body 11 and is accumulated at a specified height (specified thickness).

[0062] Thus, the electrode layer 61 is formed on the end surface 111 of the body 11 and the end surface 211 of the first internal electrode 20 (see Figure 2 、 Figure 3 ). It should be noted that 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] Then, using the AD method, pores 60P are formed when forming the electrode layer 61. The pore area ratio when forming the pores 60P varies depending on the blowing conditions based on the AD method. It should be noted that the pore area ratio is determined by the film formation rate and film formation time, etc.

[0064] Next, using the AD method, electrode layer 62 is formed on end surface 112 of body 11 and end surfaces 311 of the plurality of second internal electrodes 30 ( S13 ). Electrode layer 62 functions as an external electrode of multilayer ceramic capacitor 10 . The method for forming electrode layer 62 is the same as that for forming electrode layer 61 , so its description is omitted.

[0065] By using the above-described manufacturing method, the multilayer ceramic capacitor 10 having the above-described structure can be manufactured easily and more reliably.

[0066] The external electrodes of the multilayer ceramic capacitor 10 are realized by forming the electrode layers 61 and 62 using the AD method. That is, a part of the steps for forming the external electrodes can be omitted, and the external electrodes can be formed by a simple method.

[0067] Furthermore, electrode layers 61 and 62 do not contain a glass component. That is, no reaction layer is formed between multilayer ceramic layer 50 and electrode layers 61 and 62. Therefore, a decrease in the strength of multilayer ceramic capacitor 10 can be suppressed.

[0068] (Relationship between Porosity Area Ratios of Electrode Layers 61 and 62)

[0069] use Figure 7 , to illustrate the detailed relationship between the porosity area ratios in the electrode layers 61 and 62. Figure 7 This is a table showing the correlation between the porosity, mechanical strength, and sealing properties. As an example, Figure 7 The values ​​shown show the correlation when the electrode layers 61 and 62 are formed to a thickness of approximately 10 μm.

[0070] Figure 7 The mechanical strength and sealing properties shown are defined as follows. Mechanical strength is measured by evaluating the physical and mechanical strength during thermal cycle and thermal shock tests. Sealing is measured by evaluating the degree to which foreign matter is prevented from entering the body 11 of the multilayer ceramic capacitor 10. The porosity area ratio is determined by factors such as the film formation rate and film formation time.

[0071] like Figure 7 As shown in FIG. 1 , if the structure contains no glass and has a porosity of 3% or more and less than 25%, the desired reliability can be reliably achieved in actual use. More specifically, by having a structure that contains no glass and has a porosity of 3% or more and less than 25%, a laminated ceramic capacitor 10 can be realized that has a high sealing performance while suppressing a decrease in mechanical strength.

[0072] [Second embodiment]

[0073] A multilayer ceramic capacitor according to a second embodiment of the present invention will be described with reference to the accompanying drawings. The multilayer ceramic capacitor according to the second embodiment differs from the multilayer ceramic capacitor 10 according to the first embodiment in that it includes external electrodes 81 and 82. The remaining structure of the ceramic capacitor according to the second embodiment is the same as that of the multilayer ceramic capacitor according to the first embodiment, and description of the common features will be omitted.

[0074] like Figure 8As shown, the multilayer ceramic capacitor 10A includes external electrodes 81 and 82. External electrode 81 is a laminated structure of electrode films 811 and 812. Electrode film 811 covers the outer surface of electrode layer 61, while electrode film 812 covers the outer surface of electrode film 811. External electrode 82 is a laminated structure of electrode films 821 and 822. Electrode film 821 covers the outer surface of electrode layer 62, while electrode film 822 covers the outer surface of electrode film 821. External electrodes 81 and 82 correspond to the "second external electrodes" in the present invention.

[0075] More specifically, external electrode 81 includes electrode film 811 and electrode film 812, which are formed by plating. For example, electrode film 811 is a nickel (Ni) plated layer, and electrode film 812 is a tin (Sn) plated layer. External electrode 82 is also formed by plating in the same manner as external electrode 81. For example, electrode film 821 is a nickel (Ni) plated layer, and electrode film 822 is a tin (Sn) plated layer. It should be noted that the thickness of the terminal electrode comprising electrode layer 61 and external electrode 81, and the thickness of the terminal electrode comprising electrode layer 62 and external electrode 82, are preferably 8 μm or greater and less than 20 μm.

[0076] The presence of voids 60P in the electrode layers 61 and 62 of the multilayer ceramic capacitor 10A alleviates internal stress. This reduces the difference in thermal expansion coefficient between the electrode layers 61 and 62 and the body 11 caused by thermal shock, etc. Consequently, separation between the body 11 and the electrode layers 61 and 62 is suppressed.

[0077] Furthermore, electrode layers 61 and 62 do not contain a glass component. That is, no reaction layer is formed between multilayer ceramic layer 50 and electrode layers 61 and 62. Therefore, a decrease in the strength of multilayer ceramic capacitor 10A can be suppressed.

[0078] Furthermore, the multilayer ceramic capacitor 10A includes external electrodes 81 and 82. This further improves the sealing performance of the multilayer ceramic capacitor 10A.

[0079] Description of Reference Numerals

[0080] 10, 10A…Multilayer ceramic capacitor;

[0081] 11…ontology;

[0082] 20, 30…internal electrodes;

[0083] 50… stacked ceramic layers;

[0084] 60P…pore;

[0085] 61, 62…electrode layer;

[0086] 81, 82…external electrodes;

[0087] 91… Chamber;

[0088] 92… workbench;

[0089] 93…Aerosol generator;

[0090] 111, 112, 211, 212, 311, 312…end faces;

[0091] 600…copper powder;

[0092] 811, 812, 821, 822…electrode membrane.

Claims

1. An electronic component comprising: an electronic component body including a plurality of internal electrodes; and a first external electrode including a metal film that does not include a glass component and has pores therein, The electronic component body has a first end surface and a second end surface exposing the internal electrode. The first external electrode is formed at least on the exposed portion of the internal electrode and the first end surface and the second end surface. The porosity area ratio in the cross section of the metal film is 3% or more and less than 25%.

2. The electronic component according to claim 1, wherein The thickness of the metal film is greater than or equal to 3 μm and less than or equal to 25 μm.

3. The electronic component according to claim 1, wherein The electronic component includes a second external electrode covering the first external electrode, The second external electrode is formed by plating.

4. A method for manufacturing an electronic component, comprising the following steps: forming an electronic component body having a plurality of internal electrodes; and A first external electrode is formed on at least the exposed portion of the internal electrode in the electronic component body and the first and second end surfaces of the electronic component body by an aerosol deposition method, wherein the first external electrode includes a metal film that does not contain a glass component and has pores therein. The porosity area ratio in the cross section of the metal film is 3% or more and less than 25%.

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