Multilayer capacitor

Abstract

A multilayer capacitor is provided. The multilayer capacitor includes a main body including a stacked structure of a plurality of dielectric layers and a plurality of internal electrodes stacked with the dielectric layers interposed between the plurality of internal electrodes, an external electrode formed on an outer surface of the main body to be connected to the internal electrodes, and including a first electrode layer covering a first surface of the main body exposing the internal electrodes and a second electrode layer covering the first electrode layer, a first metal oxide layer disposed between the first electrode layer and the second electrode layer and having a discontinuous region, and a second metal oxide layer covering at least a portion of a surface of the main body on which the external electrode is not disposed and having a multilayer structure.

Description

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2020-0162565, filed on November 27, 2020, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure relates to a multilayer capacitor. Background Technology

[0003] A capacitor is a device capable of storing electrical charge, and it typically works on the principle that charge accumulates in each electrode when two electrodes are positioned opposite each other and a voltage is applied to them. When a direct current (DC) voltage is applied to a capacitor, current flows through the capacitor, accumulating charge; however, once the charge accumulation is complete, current stops flowing in the capacitor. Conversely, when an alternating current (AC) voltage is applied to a capacitor, alternating current flows through the capacitor, and the polarities of the electrodes alternate.

[0004] Such capacitors can be classified into several types of capacitors according to the type of insulator disposed between the electrodes, such as aluminum electrolytic capacitors with electrodes formed of aluminum and a thin oxide layer disposed between the aluminum electrodes, tantalum capacitors using tantalum as the electrode material, ceramic capacitors using a dielectric material with a high dielectric constant (such as barium titanate) between the electrodes, multilayer ceramic capacitors (MLCCs) using ceramic with a high dielectric constant as the dielectric material disposed between the electrodes in a multilayer structure, and film capacitors using polystyrene film as the dielectric material disposed between the electrodes, etc.

[0005] Among these capacitors, multilayer ceramic capacitors have recently been widely used in various fields, such as high-frequency circuits, due to their excellent temperature and frequency characteristics and ability to be implemented in small sizes. In recent years, efforts have been made to achieve even smaller multilayer ceramic capacitors, for which the dielectric layer and internal electrodes are formed in thin layers.

[0006] In recent years, numerous attempts have been made in the field of multilayer capacitors to improve moisture resistance reliability by reducing defects caused by the penetration of moisture or plating solutions. However, as a method, when the capping layer or outer electrode of the capacitor body is formed to be thicker, there may be a problem of increased component size and reduced capacitance for the same size. Summary of the Invention

[0007] One aspect of this disclosure provides a multilayer capacitor with improved moisture-proof reliability.

[0008] According to one aspect of this disclosure, a multilayer capacitor may include: a body having a stacked structure of stacked dielectric layers and stacked internal electrodes with the dielectric layers interposed between the internal electrodes; an external electrode formed on an outer surface of the body to connect to the internal electrodes, and including a first electrode layer and a second electrode layer, the first electrode layer covering a first surface of the body exposing the internal electrodes, and the second electrode layer covering the first electrode layer; a first metal oxide layer disposed between the first electrode layer and the second electrode layer and having discontinuous regions; and a second metal oxide layer covering at least a portion of the surface of the body on which the external electrodes are not disposed and having a multilayer structure.

[0009] The first metal oxide layer and the second metal oxide layer can be in contact with each other.

[0010] The boundary between the first metal oxide layer and the second metal oxide layer may be located at the end of the second electrode layer.

[0011] The first metal oxide layer and the second metal oxide layer may include the same metal oxide composition.

[0012] The second metal oxide layer may cover the second surface and the third surface of the body, the second surface being perpendicular to the stacking direction of the plurality of internal electrodes, and the third surface being perpendicular to the first surface and the second surface of the body.

[0013] The second metal oxide layer may cover the entire second surface and the third surface of the body.

[0014] At least a portion of the discontinuous region of the first metal oxide layer may be filled with at least one of the first electrode layer and the second electrode layer.

[0015] The first electrode layer and the second electrode layer may comprise the same material.

[0016] The first electrode layer and the second electrode layer may include at least one of copper (Cu) and nickel (Ni).

[0017] The first electrode layer and the second electrode layer may comprise metal oxides formed using the same components as those included in the first metal oxide layer.

[0018] The first metal oxide layer may further include a glass component.

[0019] The multilayer structure of the second metal oxide layer may include a stacked structure of a first layer and a second layer with different components.

[0020] The first and second layers may be stacked alternately at least twice.

[0021] The first layer can be divided into multiple regions through a first gap, and the second layer can be divided into multiple regions through a second gap.

[0022] The first gap and the second gap can be configured not to overlap in the thickness direction of the first layer and the second layer.

[0023] The first metal oxide layer may have a multilayer structure.

[0024] The surface of the first metal oxide layer may have an irregular shape.

[0025] A groove may be formed on the surface of the body, and the second metal oxide layer may fill the groove.

[0026] The external electrode may further include an additional electrode layer covering the second electrode layer, and the end of the additional electrode layer may cover the second metal oxide layer. Attached Figure Description

[0027] The above and other aspects, features and advantages of this disclosure will be more clearly understood by taking into account the accompanying drawings and the following detailed description, in which:

[0028] Figure 1 This is a schematic perspective view showing the appearance of a multilayer capacitor according to an exemplary embodiment of the present disclosure;

[0029] Figure 2 It is along Figure 1 A cross-sectional view of the multilayer capacitor taken from line II′;

[0030] Figure 3 It is along Figure 1 A cross-sectional view of a multilayer capacitor taken from line II-II′;

[0031] Figure 4 yes Figure 2 A magnified view of part of region A;

[0032] Figure 5 yes Figure 2 A magnified view of part of region B;

[0033] Figure 6 This illustrates another exemplary embodiment of the present disclosure. Figure 2 A magnified view of part of region B;

[0034] Figure 7 This is another exemplary embodiment illustrating the second metal oxide layer of this disclosure. Figure 2 A magnified view of part of region B;

[0035] Figure 8 This is another exemplary embodiment illustrating the second metal oxide layer of this disclosure. Figure 2 A magnified view of part of region B; and

[0036] Figure 9 yes Figure 2 A magnified view of part of region A. Detailed Implementation

[0037] In the following, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, exemplary embodiments of the present disclosure may be modified in many different forms, and the scope of the present disclosure is not limited to the exemplary embodiments described below. In addition, exemplary embodiments of the present disclosure are provided to explain the present disclosure more completely to those skilled in the art. Therefore, for the sake of clarity, the shapes and sizes of the elements in the drawings may be exaggerated, and the elements indicated by the same reference numerals in the drawings are the same elements.

[0038] Furthermore, in the accompanying drawings, for the sake of clarity in describing this disclosure, parts irrelevant to the description will be omitted, the thickness of certain layers and regions will be exaggerated for clarity, and components having the same function within the scope of the same concept will be indicated by the same reference numerals. Moreover, throughout the specification, when a part "includes" a component, unless otherwise stated, this means that other components may be further included without excluding them.

[0039] Figure 1 This is a schematic perspective view showing the appearance of a multilayer capacitor according to an exemplary embodiment of the present disclosure. Figure 2 and Figure 3 They are respectively along Figure 1 Cross-sectional views of the multilayer capacitor taken from lines II′ and II-II′. Furthermore, Figures 4 to 9 yes Figure 2 A magnified view of a portion of the area.

[0040] Reference Figures 1 to 4 The multilayer capacitor 100 according to exemplary embodiments of the present disclosure may include a body 110, external electrodes 131 and 132, and a first metal oxide layer 151 and a second metal oxide layer 152. The body 110 includes a stacked dielectric layer 111 and a plurality of internal electrodes 121 and 122, with the dielectric layer 111 situated between the plurality of internal electrodes 121 and 122. Here, the first metal oxide layer 151 and the second metal oxide layer 152 prevent moisture or plating solution from penetrating from the outside. The first metal oxide layer 151 may have a discontinuous region D, and the second metal oxide layer 152 may have a multilayer structure.

[0041] The body 110 may include multiple dielectric layers 111, and can be obtained by stacking and then sintering, for example, multiple green sheets. The multiple dielectric layers 111 can be integrally formed with each other through such a sintering process. Additionally, as... Figure 1 As shown, the body 110 may have a right parallelepiped shape. The dielectric layer 111 included in the body 110 may include a ceramic material with a high dielectric constant, such as a BT-based ceramic material, i.e., a barium titanate (BaTiO3)-based ceramic material, but may also include other materials known in the prior art, as long as sufficient capacitance can be obtained. If desired, in addition to the ceramic material as the main component, the dielectric layer 111 may also include additives, organic solvents, plasticizers, binders, dispersants, etc. Here, the additives may be added in the form of metal oxides during the manufacturing process. Examples of such metal oxide additives may include at least one of MnO2, Dy2O3, BaO, MgO, Al2O3, and Cr2O3. In addition, the additives may also include SiO2, CaCO3, etc.

[0042] Each of the plurality of internal electrodes 121 and 122 can be obtained by printing and then sintering a paste comprising a conductive metal on a surface of a ceramic green sheet at a predetermined thickness. In this case, the plurality of internal electrodes may include a first internal electrode 121 and a second internal electrode 122 exposed in a direction opposite to each other (based on the Z direction in the figures) of the body 110, and the surface of the body 110 exposing the first internal electrode 121 and the second internal electrode 122 will be defined as a first surface S1. The first internal electrode 121 and the second internal electrode 122 may be connected to different external electrodes 131 and 132 respectively to have different polarities when driving a multilayer capacitor, and may be electrically isolated from each other by a dielectric layer 111 disposed between them. However, according to another exemplary embodiment, the number of external electrodes 131 and 132 or the connection manner of the internal electrodes 121 and 122 may be varied. Examples of the main materials constituting the internal electrodes 121 and 122 may include copper (Cu), nickel (Ni), silver (Ag), palladium (Pd), etc., or alloys thereof.

[0043] The external electrodes 131 and 132 may include a first external electrode 131 and a second external electrode 132 formed on the outer surface of the body 110 and electrically connected to the first internal electrode 121 and the second internal electrode 122, respectively. Each of the external electrodes 131 and 132 may include a first electrode layer 141 and a second electrode layer 142, and may also include an additional electrode layer 143.

[0044] A first electrode layer 141 may be disposed on a first surface S1 of the body 110. Here, the first surface S1 may correspond to the exposed surfaces of the inner electrodes 121 and 122. The first electrode layer 141 may be connected to the inner electrodes 121 and 122 and may be formed using a conductive material such as copper (Cu), nickel (Ni), or alloys thereof. The first electrode layer 141 may be formed by transferring, printing, or impregnating conductive paste onto the first surface S1 of the body 110. In this case, in addition to the first surface S1 of the body 110, the first electrode layer 141 may be formed on the entirety of a second surface S2 perpendicular to the stacking direction (X direction) of the inner electrodes 121 and 122 and a third surface S3 perpendicular to the first surface S1 and the second surface S2. However, according to an exemplary embodiment, the first electrode layer 141 may also be formed only on the first surface S1 of the body 110. A second electrode layer 142 may cover the first electrode layer 141 and may be formed using a conductive material such as nickel (Ni), copper (Cu), or alloys thereof. In this case, the second electrode layer 142 may comprise the same material as the first electrode layer 141. The second electrode layer 142 may be formed by transfer, printing, or impregnation with conductive paste to cover the first metal oxide layer 151. When the above method is used, the first electrode layer 141 and the second electrode layer 142 may be implemented in the form of a sintered electrode obtained by sintering conductive paste.

[0045] The first metal oxide layer 151 may be disposed between the first electrode layer 141 and the second electrode layer 142, and may have the following characteristics: Figure 4 The discontinuous region D shown is illustrated. The first metal oxide layer 151 effectively prevents moisture or plating solution from penetrating into the body 110 through the electrode layers 141 and 142. Therefore, in this exemplary embodiment, by implementing the first metal oxide layer 151 with a metal oxide that can be coated relatively thinly and uniformly, the dimensions of the outer electrodes 131 and 132 can be kept small, while improving moisture resistance. Considering this function, the metal oxide component included in the first metal oxide layer 151 may include oxides of, for example, silicon (Si), aluminum (Al), zirconium (Zr), lithium (Li), or hafnium (Hf).

[0046] The first metal oxide layer 151 may include discontinuous regions D. Here, at least some of the discontinuous regions D may be filled with at least one of the first electrode layer 141 and the second electrode layer 142, such that the first electrode layer 141 and the second electrode layer 142 can be connected to each other. Electrical connection paths between the first electrode layer 141 and the second electrode layer 142 can be formed through the discontinuous regions D. In the process of sintering the first electrode layer 141 and the second electrode layer 142, the discontinuous regions D of the first metal oxide layer 151 can be formed as the metal oxide component of the first metal oxide layer 151 melts and a portion of the first metal oxide layer 151 separates. Therefore, as... Figure 9As shown, the surface of the first metal oxide layer 151 can also be formed into an irregular shape. When viewed in cross-section, it can be seen that the first metal oxide layer 151 generally maintains its layer shape, and multiple regions divided by the discontinuous region D can exist in an island-like form. Additionally, the first electrode layer 141 and the second electrode layer 142 may include metal oxide "O" having the same composition as that contained in the first metal oxide layer 151. In this case, the metal oxide of the first metal oxide layer 151 or the metal oxide O present in the first electrode layer 141 and the second electrode layer 142 can be fused together with and react with the glass components of the first electrode layer 141 and the second electrode layer 142. Therefore, the first metal oxide layer 151 not only includes metal oxides but may also partially include glass components. Furthermore, the first metal oxide layer 151 may have, as shown in the diagram... Figure 4 The multilayer structure is shown by the dashed lines. This structure can be obtained by simultaneously forming a first metal oxide layer 151 and a second metal oxide layer 152 in the multilayer structure, as will be described later. However, since a portion of the first metal oxide layer 151 is lost during the sintering process, the first metal oxide layer 151 does not have a significant multilayer structure compared to the second metal oxide layer 152.

[0047] The second metal oxide layer 152 may cover at least a portion of the surface of the body 110 on which the external electrodes 131 and 132 are not disposed. In this exemplary embodiment, the second metal oxide layer 152 may cover the second surface S2 and the third surface S3 of the body 110. Furthermore, the second metal oxide layer 152 may cover the entire second surface S2 and the third surface S3. Since the surface of the body 110 is not exposed through this full surface coverage structure, the body 110 can effectively block external moisture. In addition, the second metal oxide layer 152 may include a multilayer structure, for example, as shown in the example. Figure 5 The stacked structure shown, with the first layer 161 and the second layer 162 superimposed on top of each other, further improves moisture resistance. In this case, the first layer 161 and the second layer 162 may comprise different components. For example, the first layer 161 may comprise Al2O3, and the second layer 162 may comprise HfO2. Furthermore, as... Figure 6 As shown, the first layer 161 and the second layer 162 can be alternately stacked two or more times. Additionally, as... Figure 7As shown, in the second metal oxide layer 152, the first layer 161 can be divided into multiple regions by the first gap G1, and similarly, the second layer 162 can be divided into multiple regions by the second gap G2. In this case, the positions of the first gap G1 and the second gap G2 can be adjusted to improve the moisture-proof performance. Specifically, in at least some regions of the stacked structure of the second metal oxide layer 152, the first gap G1 and the second gap G2 can be configured so that they do not overlap in the thickness direction (vertical direction based on the figures) of the first layer 161 and the second layer 162.

[0048] like Figure 2 As shown, the first metal oxide layer 151 and the second metal oxide layer 152 may be in contact with each other. In this case, the boundary between the first metal oxide layer 151 and the second metal oxide layer 152 may be located at the end of the second electrode layer 142. For example, this connection structure of the first metal oxide layer 151 and the second metal oxide layer 152 can be obtained by forming a multilayer metal oxide film on the entire surface of the first electrode layer 141 and the body 110 after the formation of the first electrode layer 141. The first metal oxide layer 151 and the second metal oxide layer 152 may include the same metal oxide composition. As described in the above example, the second metal oxide layer 152 may also include oxides of, for example, silicon (Si), aluminum (Al), zirconium (Zr), lithium (Li), or hafnium (Hf). As mentioned above, the second metal oxide layer 152 may be formed together with the first metal oxide layer 151, rather than in the final step after the formation of all the outer electrodes 131 and 132. In this case, the end of the additional electrode layer 143 in the outer electrodes 131 and 132 may cover the second metal oxide layer 152.

[0049] The second metal oxide layer 152 may be thicker than the first metal oxide layer 151 (t2>t1). This is because, as described above, a portion of the first metal oxide layer 151 is partially lost during the sintering process of the outer electrodes 131 and 132. Furthermore, considering the irregular shape of the first metal oxide layer 151, its thickness can be defined as the maximum thickness in the corresponding region. The thickness of the second metal oxide layer 152 can also be defined as the maximum thickness. However, since the second metal oxide layer 152 has a relatively uniform thickness compared to the first metal oxide layer 151, its thickness can be defined as the average thickness.

[0050] Reference Figure 8The second metal oxide layer 152 can fill the grooves formed on the surface of the body 110. In this case, the second metal oxide layer 152 can be formed along the surface of the groove, that is, following the surface of the groove. The grooves on the surface of the body 110 can be areas where the body 110 has defects, and can be paths through which moisture or plating solution can easily penetrate. As in this exemplary embodiment, moisture-proof reliability can be further improved by filling the grooves on the surface of the body 110 with the second metal oxide layer 152.

[0051] Refer again Figure 2 The remaining construction of the external electrodes 131 and 132 will be described below. Each of the external electrodes 131 and 132 may include an additional electrode layer 143 covering the second electrode layer 142. The additional electrode layer 143 may be a plating layer and may be implemented in a multilayer structure including nickel (Ni), tin (Sn), etc. As described above, when the plating layer is formed, the plating solution can be effectively prevented from penetrating into the body 110 by the first metal oxide layer 151 and the second metal oxide layer 152. In addition to the plating layer, the additional electrode layer 143 may also include a conductive resin electrode mixed with a conductive material and a resin. In this case, the conductive resin electrode may be disposed on the plating layer and the second electrode layer 142.

[0052] As described above, the moisture resistance reliability of multilayer capacitors can be improved according to the exemplary embodiments in this disclosure.

[0053] While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations may be made without departing from the scope of the invention as defined by the appended claims.

Claims

1. A multilayer capacitor, comprising: The main body includes a stacked structure comprising multiple stacked dielectric layers and multiple stacked internal electrodes, with the dielectric layers located between the multiple internal electrodes; An outer electrode is formed on the outer surface of the body to connect to the inner electrode, and includes a first electrode layer and a second electrode layer, the first electrode layer covering a first surface of the body that exposes the inner electrode, and the second electrode layer covering the first electrode layer. A first metal oxide layer is disposed between the first electrode layer and the second electrode layer and has a discontinuous region; as well as A second metal oxide layer covers at least a portion of the surface of the body on which the external electrode is not disposed and has a multilayer structure. The first electrode layer and the second electrode layer comprise metal oxides, and the metal oxides are also included in the first metal oxide layer.

2. The multilayer capacitor as claimed in claim 1, wherein, The first metal oxide layer and the second metal oxide layer are in contact with each other.

3. The multilayer capacitor as described in claim 2, wherein, The boundary between the first metal oxide layer and the second metal oxide layer is located at the end of the second electrode layer.

4. The multilayer capacitor as claimed in claim 1, wherein, The first metal oxide layer and the second metal oxide layer comprise the same metal oxide composition.

5. The multilayer capacitor as claimed in claim 1, wherein, The second metal oxide layer covers the second surface and the third surface of the body, the second surface being perpendicular to the stacking direction of the plurality of internal electrodes, and the third surface being perpendicular to the first surface and the second surface.

6. The multilayer capacitor as claimed in claim 5, wherein, The second metal oxide layer covers the entire outer surface of the body on which the external electrode is not disposed.

7. The multilayer capacitor as claimed in claim 1, wherein, At least a portion of the discontinuous region of the first metal oxide layer is filled with at least one of the first electrode layer and the second electrode layer.

8. The multilayer capacitor as claimed in claim 1, wherein, The first electrode layer and the second electrode layer comprise the same material.

9. The multilayer capacitor as claimed in claim 1, wherein, The first electrode layer and the second electrode layer comprise at least one of copper and nickel.

10. The multilayer capacitor as claimed in claim 1, wherein, The metal oxide components contained in the first metal oxide layer include oxides of silicon, aluminum, zirconium, lithium, or hafnium.

11. The multilayer capacitor as claimed in claim 1, wherein, The first metal oxide layer also includes a glass component.

12. The multilayer capacitor as claimed in claim 1, wherein, The multilayer structure of the second metal oxide layer includes a first layer and a second layer. The first layer is disposed on the surface of the body on which the external electrode is not disposed and has a multilayer structure. The second layer is disposed on the first layer, wherein the components included in the first layer are different from the components included in the second layer.

13. The multilayer capacitor as claimed in claim 12, wherein, The first and second layers are stacked alternately at least twice.

14. The multilayer capacitor as claimed in claim 13, wherein, The first layer is divided into multiple regions by a first gap, and The second layer is divided into multiple regions by a second gap.

15. The multilayer capacitor as claimed in claim 14, wherein, The first gap and the second gap are configured not to overlap in the thickness direction of the first layer and the second layer.

16. The multilayer capacitor as claimed in claim 1, wherein, The first metal oxide layer has a multilayer structure.

17. The multilayer capacitor as claimed in claim 1, wherein, The surface of the first metal oxide layer has an irregular shape.

18. The multilayer capacitor as claimed in claim 1, wherein, The surface of the body includes grooves, and the second metal oxide layer fills the grooves.

19. The multilayer capacitor as claimed in claim 1, wherein, The external electrode further includes an additional electrode layer covering the second electrode layer, and the end of the additional electrode layer covers the second metal oxide layer.

20. The multilayer capacitor as claimed in claim 1, wherein, The thickness of the first metal oxide layer is less than the thickness of the second metal oxide layer.

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