Multilayer capacitor

Abstract

To provide a laminate type capacitor.SOLUTION: A laminate type capacitor according to one embodiment of the present invention includes a main body including a laminate structure having a plurality of dielectric layers stacked and a plurality of internal electrodes that are stacked with the dielectric layers held therebetween, and an external electrode formed outside the main body and connected to the internal electrode. The external electrode includes a first electrode layer covering a first surface of the main body where the internal electrode is exposed, a glass layer covering the first electrode layer and a second surface of the main body that is perpendicular to a direction where the internal electrodes are stacked, and a second electrode layer covering the glass layer. The glass layer includes an internal region including a discontinuous region, and an external region having an end part exposed from the second electrode layer while covering the second surface of the main body.SELECTED DRAWING: Figure 2

Description

【Technical Field】 【0001】 The present invention relates to a multilayer capacitor. 【Background Art】 【0002】 A capacitor is an element that can store electricity, and generally utilizes the principle that when a voltage is applied with two electrodes facing each other, electricity is accumulated on each electrode. When a DC voltage is applied, a current flows inside the capacitor while electricity is stored, but when the accumulation is complete, the current stops flowing. On the other hand, when an AC voltage is applied, an alternating current flows while the polarity of the electrodes alternates. 【0003】 Such capacitors can be classified into various types depending on the type of insulator provided between the electrodes, such as an aluminum electrolytic capacitor that forms electrodes with aluminum and has a thin oxide film between the aluminum electrodes, a tantalum capacitor that uses tantalum as the electrode material, a ceramic capacitor that uses a dielectric with a high dielectric constant such as barium titanate between the electrodes, a multilayer ceramic capacitor (MLCC) that uses a high dielectric constant ceramic as the dielectric between the electrodes in a multilayer structure, a film capacitor that uses a polystyrene film as the dielectric between the electrodes, and the like. 【0004】 Among them, multilayer ceramic capacitors have the advantages of excellent temperature characteristics and frequency characteristics and being able to be realized in a small size, and thus have been widely applied in various fields such as high-frequency circuits in recent years. In recent years, in order to make multilayer ceramic capacitors even smaller, attempts have been continuously made to form dielectric layers and internal electrodes thinner. 【0005】 Recently, in the field of multilayer capacitors, many attempts have been made to improve moisture resistance reliability by reducing defects caused by the penetration of moisture and plating solutions. One method involves forming a thicker cover layer or external electrodes on the capacitor body, but this increases the size of the component, which leads to a decrease in capacitance for the same size. [Overview of the Initiative] [Problems that the invention aims to solve] 【0006】 One objective of the present invention is to provide a multilayer capacitor with improved moisture resistance reliability. [Means for solving the problem] 【0007】 As a method for solving the above-mentioned problems, the present invention proposes a new structure for a multilayer capacitor by example. Specifically, it includes a multilayer structure in which a plurality of dielectric layers are stacked, a main body including a plurality of internal electrodes stacked with the dielectric layers in between, and an external electrode formed outside the main body and connected to the internal electrodes, wherein the external electrode includes a first electrode layer covering a first surface of the main body in which the internal electrodes are exposed, a glass layer covering a second surface perpendicular to the direction in which the first electrode layer and the plurality of internal electrodes are stacked in the main body, and a second electrode layer covering the glass layer, wherein the glass layer includes an internal region having a discontinuous region and an external region having an end exposed from the second electrode layer while covering the second surface of the main body. 【0008】 In one embodiment, the external region can be thicker than the internal region. 【0009】 In one embodiment, at least a portion of the discontinuous region is filled with at least one of the first and second electrode layers, and the first and second electrode layers can be connected to each other. 【0010】 In one embodiment, the first and second electrode layers may contain the same material. 【0011】 In one embodiment, the first and second electrode layers may include at least one of Cu and Ni. 【0012】 In one embodiment, the first and second electrode layers may include glass having the same components as those contained in the glass layer. 【0013】 In one embodiment, the external region can expose a portion of the surface perpendicular to the direction in which the plurality of internal electrodes are stacked on the main body. 【0014】 In one embodiment, the external electrodes include first and second external electrodes facing each other, and the external region of the glass layer included in the first external electrode and the external region of the glass layer included in the second external electrode may not be connected to each other. 【0015】 In one embodiment, the portion of the glass layer that covers the second surface of the main body can be thicker than the portion that covers the first surface of the main body. 【0016】 In one embodiment, the thickness of the outer region of the glass layer can be 0.5 μm or more. 【0017】 In one embodiment, the thickness of the internal region of the glass layer can be 0.2 μm or more. 【0018】 In one embodiment, the portion of the internal region of the glass layer that covers the second surface of the main body can come into contact with the main body. 【0019】 In one embodiment, the first electrode layer does not need to cover the second surface of the main body. 【0020】 In one embodiment, a portion of the internal region may have a configuration in which the thickness decreases as you move inward from the region connected to the external region. 【0021】 In one embodiment, the surface of the internal region can be of a random shape. 【0022】 In one embodiment, the surface of the external region can be of a random shape. 【Advantages of the Invention】 【0023】 In the case of the multilayer capacitor according to an example of the present invention, the moisture resistance reliability can be improved. 【Brief Description of the Drawings】 【0024】 [Figure 1] FIG. 1 is a perspective view schematically showing the appearance of a multilayer capacitor according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along the line I-I' of the multilayer capacitor of FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view taken along the line II-II' of the multilayer capacitor of FIG. 1. [Figure 4] FIG. 4 shows an enlarged view of a partial region of FIG. 2. [Figure 5] FIG. 5 shows an enlarged view of a partial region of FIG. 2. [Figure 6] FIG. 6 shows an enlarged view of a partial region of FIG. 2. [Figure 7] FIG. 7 shows an enlarged view of a partial region of FIG. 2. [Figure 8] FIG. 8 shows an enlarged view of a partial region of FIG. 2. ' [Figure 9] FIG. 9 shows an enlarged view of a partial region of FIG. 2. 【Mode for Carrying Out the Invention】 【0025】 Embodiments of the present invention will be described below with reference to specific embodiments and accompanying drawings. However, embodiments of the present invention can be modified into several other forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, embodiments of the present invention are provided to give a more complete explanation of the present invention to a person of the ordinary skill. Accordingly, the shapes and sizes of elements in the drawings may be enlarged or reduced (or highlighted or simplified) for a clearer explanation, and elements indicated by the same reference numerals in the drawings are the same elements. 【0026】 Furthermore, in order to clearly illustrate the present invention in the drawings, parts unrelated to the explanation have been omitted, and the thickness has been enlarged to clearly represent multiple layers and regions. Components with the same function within the scope of the same concept are described using the same reference numerals. Moreover, throughout the specification, when a part "includes" a component, unless otherwise stated to the contrary, it does not mean that other components are excluded, but rather that other components may be further included. 【0027】 Figure 1 is a schematic perspective view showing the appearance of a multilayer capacitor according to one embodiment of the present invention. Figures 2 and 3 are I-I' and II-II' cross-sectional views of the multilayer capacitor of Figure 1, respectively. Figures 4 to 9 show enlarged views of a portion of Figure 2. 【0028】 Referring to Figures 1 to 4, a multilayer capacitor 100 according to one embodiment of the present invention includes a main body 110 including a dielectric layer 111 and a plurality of internal electrodes 121, 122 stacked on either side of it, and external electrodes 131, 132, the external electrodes 131, 132 including a glass layer 142. Here, the glass layer 142 can prevent the intrusion of moisture and plating solutions from the outside and includes an internal region 151 having a discontinuous region D and an external region 152 having an end exposed from the second electrode layer 143. 【0029】 The main body 110 includes a plurality of dielectric layers 111, which can be obtained, for example, by laminating a plurality of green sheets and then sintering them. This sintering process allows the plurality of dielectric layers 111 to have an integrated form. As shown in Figure 1, the main body 110 can have a shape similar to a rectangular parallelepiped. The dielectric layers 111 contained in the main body 110 can include ceramic materials having a high dielectric constant, such as BT-based ceramics, i.e., barium titanate (BaTiO3) ceramics, but other materials known in the art can also be used as long as sufficient capacitance can be obtained. The dielectric layers 111 may further contain, if necessary, additives, organic solvents, plasticizers, binders, and dispersants, along with the ceramic material as the main component. In the case of additives, these can be added in the form of metal oxides during the manufacturing process. Examples of such metal oxide additives include at least one of MnO2, Dy2O3, BaO, MgO, Al2O3, SiO2, Cr2O3, and CaCO3. 【0030】 Multiple internal electrodes 121, 122 are obtained by printing a paste containing a conductive metal to a predetermined thickness onto one surface of a ceramic green sheet, and then sintering it. In this case, the multiple internal electrodes 121, 122 may include first and second internal electrodes 121, 122 exposed on the main body 110 in opposing directions (Z direction with respect to the drawing), and the surface on the main body 110 where the first and second internal electrodes 121, 122 are exposed is defined as the first surface S1. The first and second internal electrodes 121, 122 are connected to different external electrodes 131, 132, and can have different polarities when driven, and can be electrically isolated from each other by a dielectric layer 111 placed between them. However, the number of external electrodes 131, 132 and the method of connection with the internal electrodes 121, 122 can vary depending on the embodiment. Examples of main constituent materials for the internal electrodes 121, 122 include Cu, Ni, Ag, and Pd, and alloys of these can also be used. 【0031】 The external electrodes 131 and 132 are formed outside the main body 110 and may include first and second external electrodes 131 and 132 connected to first and second internal electrodes 121 and 122, respectively. The external electrodes 131 and 132 include a first electrode layer 141, a glass layer 142, and a second electrode layer 143. Additional electrode layers 144 and 145 may be placed on the second electrode layer 143, however, the additional electrode layers 144 and 145 may be omitted depending on the embodiment. 【0032】 The first electrode layer 141 covers the first surface S1 of the main body 110, and as described above, the first surface S1 corresponds to the surface on which the internal electrodes 121 and 122 are exposed. The first electrode layer 141 is connected to the internal electrodes 121 and 122 and can be formed of a conductive material, such as Cu, Ni, or alloys thereof. The first electrode layer 141 can be formed by transferring a conductive paste to the first surface S1 of the main body 110, or by printing or dipping. In this embodiment, it has been shown that the first electrode layer 141 is formed only on the first surface S1 of the main body 110, but the first electrode layer 141 can also be formed on the second surface S2 perpendicular to the stacking direction (X direction) of the internal electrodes 121 and 122 on the main body 110, and on the third surface S3 perpendicular to both the first surface S1 and the second surface S2. The second electrode layer 143 covers the first electrode layer 141 and the glass layer 142 and can be formed from a conductive material, such as Ni, Cu, or an alloy thereof. In this case, the second electrode layer 143 may contain the same material as the first electrode layer 141. The second electrode layer 143 can be formed by transferring, printing, or dipping a conductive paste to cover the glass layer 142. When using the above-described method, the first and second electrode layers 141 and 143 can be realized in the form of fired electrodes obtained by firing a conductive paste. 【0033】 The glass layer 142 covers the first electrode layer 141 and the second surface S2 of the main body 110, and can also cover the third surface S3 of the main body 110. As shown in the configurations in Figures 4 and 5, the glass layer 142 includes an internal region 151 having a discontinuous region D, and an external region 152 that covers the second surface S2 of the main body 110 and has an end exposed from the second electrode layer 143. Here, the end of the external region 152 can be in a form that protrudes laterally from the second electrode layer 143. In Figure 5, other components of the external electrodes 131 and 132, in addition to the glass layer 142 and the second electrode layer 143, are not shown. The glass layer 142 is a configuration adopted to protect areas with weak moisture resistance reliability, such as the interface between the external electrodes 131 and 132 and the main body 110. Therefore, the glass layer 142 can be formed from a material with excellent properties such as reactivity with ceramics, density, and resistance to plating. For example, Ba-Zn glass, Dy-Zr glass, etc., can be used, and other types of glass containing B and Si components can also be used. 【0034】 In the case of the internal region 151 of the glass layer 142, it includes a discontinuous region D, of which at least a portion is filled with at least one of the first and second electrode layers 141 and 143, allowing the first and second electrode layers 141 and 143 to be connected to each other. Such a discontinuous region D allows for the formation of an electrical connection path between the first and second electrode layers 141 and 143. The discontinuous region D of the glass layer 142 can be formed by melting the glass component during the firing process of the first and second electrode layers 141 and 143, and cutting out a portion of the glass layer 142. As a result, the glass layer 142 can be obtained with a random shape on the surface of the internal region 151, as shown in Figure 9. When viewed from a cross-section, the glass layer 142 appears to maintain its layered shape overall, and the numerous regions separated by the discontinuous region D can exist in an island shape. Furthermore, the first and second electrode layers 141 and 143 can contain glass g of the same composition as that contained in the glass layer 142. As shown in the illustrated configuration, the portion of the internal region 151 of the glass layer 142 that covers the second surface S2 of the main body 110 can come into contact with the main body 110. In this case, the first electrode layer 141 may not cover the second surface S2 of the main body 110. 【0035】 As described above, the external region 152 of the glass layer 142 has an end exposed from the second electrode layer 143, which effectively blocks the penetration of moisture, plating solution, etc., at the interface between the external electrodes 131, 132 and the main body 110. In this case, as shown in the illustrated form, the external region 152 can be formed only around the ends of the external electrodes 131, 132, thereby exposing a portion of the second surface S2 of the main body 110. Similarly, the external region 152 can also expose a portion of the third surface S3 of the main body 110. If the external region 152 of the glass layer 142 completely covers the second surface S3 or the third surface S3 of the main body 110, the glass component of the glass layer 142 may react with the glass component present in the main body 110 during the firing and subsequent heat treatment processes of the external electrodes 131, 132 to form a secondary phase. However, such a secondary phase may reduce the insulation resistance of the main body 110, which could lead to a decrease in reliability. In this embodiment, the glass layer 142 of the first external electrode 131 and the glass layer 142 of the second external electrode 132 are not connected to each other, and more specifically, the external regions 152 of the glass layer 142 are not connected. This reduces the generation of a secondary phase due to the reaction between the main body 110 and the glass layer 142. 【0036】 In this embodiment, the glass layer 142 can have an outer region 152 that is thicker than the inner region 151. That is, in the configurations shown in Figures 4 and 5, the thickness t3 of the outer region 152 can be greater than the thickness t1 of the inner region 151. This configuration can be obtained when more glass component loss occurs in the inner region 151 than in the outer region 152. To obtain sufficient protective effect from the glass layer 142, the thickness t3 of the outer region 152 can be 0.5 μm or more, and the thickness t1 of the inner region 151 can be 0.2 μm or more. Here, each thickness t1 and t2 can be based on a cross-section perpendicular to the second direction (Y direction) as shown in Figure 2, and as an example, the cross-section of the intermediate region in the second direction (Y direction) of the main body 110 can be selected. Also, as shown in the modified example in Figure 6, the change in thickness can occur gradually at the connection between the inner region 151 and the outer region 152. Specifically, a portion of the internal region 151 of the glass layer 142 can be realized in a form where the thickness decreases as you move inward (to the left, relative to Figure 6) in a region connected to the external region 152. On the other hand, considering that the glass layer 142 may have a random shape, the thickness of the glass layer 142 can be defined as the maximum thickness in that region. 【0037】 Furthermore, the thickness t2 of the region of the glass layer 142 that covers the second surface S2 of the main body 110 can be greater than the thickness t1 of the region that covers the first surface S1 of the main body 110. This configuration can be obtained when there is relatively little loss of the glass component of the glass layer 142 in the region that covers the second surface S2 of the main body 110. 【0038】 Figures 7 and 8 show deformed forms of the glass layer 142. First, in the embodiment of Figure 7, the external region 152 of the glass layer 142 does not protrude laterally from the second electrode layer 143. That is, only the outermost side surface of the glass layer 142 can be exposed from the second electrode layer 143 to form the external region 152. In the embodiment of Figure 8, the external region 152 of the glass layer 142 has a random shape, and its thickness can decrease as it moves away from the second electrode layer 143. Such shapes of the glass layer 142 can be obtained when the fluid glass layer 142 hardens in a state where it spreads outward during the firing process of the external electrodes 131 and 132. 【0039】 Referring again to Figure 2, the remaining configuration of the external electrodes 131 and 132 can be described. The external electrodes 131 and 132 may include additional electrode layers 144 and 145 that cover the second electrode layer 143. The additional electrode layers 144 and 145 may include a conductive resin electrode 144 and a plating layer 145. The conductive resin electrode 144 may be in the form of a mixture of conductive material and resin, although this may be omitted depending on the embodiment. In this case, the plating layer 145 can come into immediate contact with the second electrode layer 143. The plating layer 145 can be realized as a multilayer structure containing Ni, Sn, etc., and as described above, the glass layer 142 can effectively block the penetration of the plating solution into the main body 110 side when the plating layer 145 is formed. 【0040】 The present invention is not limited by the embodiments described above and the accompanying drawings, but is limited by the claims provided. Accordingly, it is obvious to those with ordinary skill in the art that various forms of substitution, modification, and alteration are possible without departing from the technical idea of ​​the present invention as described in the claims, and this can also be said to be within the scope of the technical idea described in the claims. [Explanation of symbols] 【0041】 100: Multilayer capacitor 110: Main unit 111: Dielectric layer 121, 122: Internal electrode 131, 132: External electrode 141:First electrode layer 142: Glass layer 143:Second electrode layer 144, 145: Additional electrode layer 151: Internal area 152: External area

Claims

[Claim 1] A main body comprising a laminated structure in which multiple dielectric layers are stacked, and multiple internal electrodes stacked with the multiple dielectric layers sandwiched between them, The body includes an external electrode formed on the outside of the main body and connected to the plurality of internal electrodes, The external electrode includes a first electrode layer covering a first surface of the main body on which the plurality of internal electrodes are exposed, a glass layer covering a second surface perpendicular to the direction in which the first electrode layer and the plurality of internal electrodes are stacked on the main body, a second electrode layer covering the glass layer, and a conductive resin layer covering the second electrode layer. The glass layer includes an internal region having a discontinuous area and an external region having an end exposed from the second electrode layer while covering the second surface of the main body. The conductive resin layer is a multilayer capacitor in contact with the external region. [Claim 2] The multilayer capacitor according to claim 1, wherein the external region is thicker than the internal region. [Claim 3] The stacked capacitor according to claim 1 or 2, wherein at least a portion of the discontinuous region is filled with at least one of the first electrode layer and the second electrode layer, and the first electrode layer and the second electrode layer are connected to each other. [Claim 4] A multilayer capacitor according to any one of claims 1 to 3, wherein the first electrode layer and the second electrode layer contain the same material. [Claim 5] The multilayer capacitor according to any one of claims 1 to 4, wherein the first electrode layer and the second electrode layer contain at least one of Cu and Ni. [Claim 6] The stacked capacitor according to any one of claims 1 to 5, wherein the first electrode layer and the second electrode layer contain glass having the same composition as that contained in the glass layer. [Claim 7] The multilayer capacitor according to any one of claims 1 to 6, wherein the external region exposes a portion of a surface perpendicular to the direction in which the plurality of internal electrodes are stacked in the main body. [Claim 8] The multilayer capacitor according to any one of claims 1 to 7, wherein the external electrodes include a first external electrode and a second external electrode facing each other, and the external region of the glass layer included in the first external electrode and the external region of the glass layer included in the second external electrode are not connected to each other. [Claim 9] A laminated capacitor according to any one of claims 1 to 8, wherein the region of the glass layer covering the second surface of the main body is thicker than the region covering the first surface of the main body. [Claim 10] The stacked capacitor according to any one of claims 1 to 9, wherein the thickness of the outer region of the glass layer is 0.5 μm or more. [Claim 11] The stacked capacitor according to any one of claims 1 to 10, wherein the thickness of the internal region of the glass layer is 0.2 μm or more. [Claim 12] The stacked capacitor according to any one of claims 1 to 11, wherein the region of the glass layer that covers the second surface of the main body is in contact with the main body. [Claim 13] The multilayer capacitor according to any one of claims 1 to 12, wherein the first electrode layer does not cover the second surface of the main body. [Claim 14] A laminated capacitor according to any one of claims 1 to 13, wherein a portion of the internal region has a shape in which the thickness decreases as you move inward from the region connected to the external region. [Claim 15] The multilayer capacitor according to any one of claims 1 to 14, wherein the surface of the internal region has a random shape. [Claim 16] The multilayer capacitor according to any one of claims 1 to 15, wherein the surface of the external region has a random shape.

Images