Multilayer capacitor

Abstract

To provide a laminated type capacitor.SOLUTION: An embodiment of the present invention includes: a main body including a plurality of dielectric layers and a plurality of internal electrodes laminated in a first direction sandwiching the dielectric layers; and an external electrode formed outside the main body and connected to the internal electrodes. The main body includes: an active unit that is an area where the plurality of internal electrodes are positioned to form an electrostatic capacitance and corresponds to the area between the internal electrodes disposed at an outermost side in the first direction of the plurality of internal electrodes; a cover unit for covering the active unit in the first direction; and a side margin unit for covering the active unit in a second direction perpendicular to the first direction. When an average grain size of the dielectric layer in a central area of the active unit is defined as A1 and an average grain size of the dielectric layer at an active-cover boundary unit adjacent to the cover unit among the active units is defined as A2, a laminated type capacitor is provided that satisfies a condition of a 1.49<A1 / A2<2.50.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to a multilayer capacitor. [Background technology]

[0002] A capacitor is a device that can store electricity. Generally, when a voltage is applied to two opposing electrodes, electricity is stored in each electrode. When a DC voltage is applied, electricity is stored and current flows inside the capacitor, but once storage is complete, the current stops flowing. On the other hand, when an AC voltage is applied, the polarity of the electrodes alternates and an AC current flows.

[0003] Such capacitors can be classified into various types depending on the type of insulator provided between the electrodes, including aluminum electrolytic capacitors, which use aluminum electrodes with a thin oxide film between the aluminum electrodes; tantalum capacitors, which use tantalum as the electrode material; ceramic capacitors, which use a high dielectric constant dielectric such as barium titanate between the electrodes; multilayer ceramic capacitors (MLCCs), which use a multilayer structure of high dielectric constant ceramics as the dielectric between the electrodes; and film capacitors, which use polystyrene film as the dielectric between the electrodes.

[0004] Among them, multilayer ceramic capacitors have excellent temperature and frequency characteristics, and can be realized in a small size, so in recent years they have been widely applied in various fields such as high-frequency circuits. In recent years, attempts have been made to make multilayer ceramic capacitors even smaller by forming thinner dielectric layers and internal electrodes. However, as components become smaller, it becomes more difficult to improve electrical and structural reliability. [Overview of the project] [Problems that the invention aims to solve]

[0005] An object of the present invention is to provide a laminated capacitor with improved reliability such as withstand voltage characteristics and capacitance characteristics by adjusting the grain size of the dielectric layer for each region.

Means for Solving the Problems

[0006] As a method for solving the above problems, the present invention proposes a new structure of a laminated capacitor by way of an example. Specifically, it includes a main body including a plurality of dielectric layers and a plurality of internal electrodes laminated in a first direction with the dielectric layers interposed therebetween, and an external electrode formed outside the main body and connected to the internal electrodes. The main body has the plurality of internal electrodes located therein to form capacitance, and includes an active portion which is a region corresponding to the space between the internal electrodes disposed outermost in the first direction among the plurality of internal electrodes, a cover portion covering the active portion in the first direction, and a side margin portion covering the active portion in a second direction perpendicular to the first direction. When the average grain size of the dielectric layer in the central region of the active portion is A1 and the average grain size of the dielectric layer at the active-cover boundary portion adjacent to the cover portion in the active portion is A2, the condition of 1.49 < A1 / A2 < 2.50 is satisfied.

[0007] In one embodiment, when a direction perpendicular to the first and second directions is defined as the third direction, with reference to the cross-sectional plane of the main body perpendicular to the third direction, when the length of the active portion in the first direction is TA and the length of the active portion in the second direction is WA, A1 is the average size of the grains existing in the A1 rectangle in the cross-sectional plane. The A1 rectangle has a horizontal length of WA / 3 and a vertical length of TA / 3, and can be symmetric with respect to the center lines in the first and second directions in the active portion.

[0008] In one embodiment, A2 is the average size of grains present in the A2 rectangle among the above-mentioned cross-sectional planes. The above-mentioned A2 rectangle has a horizontal length of WA / 3 and a vertical length of TA / 6, is symmetric with respect to the central line in the first direction in the above-mentioned active portion, and can be in contact with the innermost internal electrode arranged in the first direction among the above-mentioned plurality of internal electrodes.

[0009] In one embodiment, when the average grain size of the dielectric layer in the central region of the above-mentioned cover portion is C1 and the average grain size of the dielectric layer in the central region of the above-mentioned side margin portion is M1, the condition C1 < M1 can be satisfied.

[0010] In one embodiment, when the direction perpendicular to the first and second directions is defined as the third direction, with reference to the cross-sectional plane of the above-mentioned main body perpendicular to the third direction, when the length of the above-mentioned cover portion in the first direction is TC, C1 is the average size of grains present in the C1 rectangle among the above-mentioned cross-sectional planes. The above-mentioned C1 rectangle has a horizontal length of WA / 3 and a vertical length of TC / 3, and can be symmetric with respect to the central lines in the first and second directions in the above-mentioned cover portion.

[0011] In one embodiment, when the length of the above-mentioned side margin portion in the second direction is WM, M1 is the average size of grains present in the M1 rectangle among the above-mentioned cross-sectional planes. The above-mentioned M1 rectangle has a horizontal length of WM / 3 and a vertical length of TA / 3, and can be symmetric with respect to the central lines in the first and second directions in the above-mentioned side margin portion.

[0012] In one embodiment, when the average grain size of the dielectric layer in the cover-active boundary portion adjacent to the active portion in the above-mentioned cover portion is C2, the condition 0.9 < C2 / M1 < 1.1 can be satisfied.

[0013] In one embodiment, when the length of the cover portion in the first direction is TC, C2 is the average size of the grains present in the C2 rectangle of the cross-section, the C2 rectangle has a horizontal length of WA / 3 and a vertical length of TC / 6, is symmetrical with respect to the center line in the first direction in the cover portion, and can contact the outermost internal electrode among the plurality of internal electrodes arranged in the first direction.

[0014] In one embodiment, the dielectric layer contains a barium titanate component, and the molar ratio of Ba to Ti in the dielectric layer in the central region of the active portion can be smaller than the molar ratio of Ba to Ti in the dielectric layer in the central region of the cover portion.

[0015] In one embodiment, the molar ratio of Ba to Ti in the dielectric layer in the central region of the side margin portion can be smaller than the molar ratio of Ba to Ti in the dielectric layer in the central region of the cover portion, and larger than the molar ratio of Ba to Ti in the dielectric layer in the central region of the active portion.

[0016] In one embodiment, at least one of the plurality of dielectric layers may have an average thickness of less than 0.4 μm.

[0017] On the one hand, another aspect of the present invention includes a main body including a plurality of dielectric layers and a plurality of internal electrodes laminated in a first direction with the dielectric layers interposed therebetween, and an external electrode formed outside the main body and connected to the internal electrodes. The main body has a region corresponding to between the internal electrodes where the plurality of internal electrodes are located to form capacitance, which is an active part, a cover part covering the active part in the first direction, and a side margin part covering the active part in a second direction perpendicular to the first direction. When the average grain size of the dielectric layer in the central region of the active part is A1 and the average grain size of the dielectric layer at the active-side boundary adjacent to the side margin part in the active part is A3, a multilayer capacitor is provided that satisfies the condition of 1.14 ≦ A1 / A3 < 1.50.

Advantages of the Invention

[0018] In the case of the multilayer capacitor according to an example of the present invention, the withstand voltage characteristics, capacitance characteristics, etc. can be improved.

Brief Description of the Drawings

[0019] [Figure 1] It is a perspective view schematically showing the appearance of the multilayer capacitor according to an embodiment of the present invention. [Figure 2] In the multilayer capacitor of FIG. 1, it is a cross-sectional view along the line I-I'. [Figure 3] In the multilayer capacitor of FIG. 1, it is a cross-sectional view along the line II-II'. [Figure 4] It shows a subdivision of the main body region in FIG. 3. [Figure 5] [[ID=二十七]]It shows the form of dielectric grains for each region of the main body. [Figure 6] It shows the form of dielectric grains for each region of the main body. [Figure 7] It shows the form of dielectric grains for each region of the main body. [Figure 8]This shows the morphology of dielectric grains in each region of the main body. [Figure 9] This shows the morphology of dielectric grains in each region of the main body. [Modes for carrying out the invention]

[0020] 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.

[0021] 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.

[0022] Figure 1 is a schematic perspective view showing the appearance of a multilayer capacitor according to one embodiment of the present invention. Figure 2 is a cross-sectional view of the multilayer capacitor of Figure 1 along the line I-I'. Figure 3 is a cross-sectional view of the multilayer capacitor of Figure 1 along the line II-II', and Figure 4 shows a subdivided view of the main body region in Figure 3. Figures 5 to 9 show the dielectric grain morphology for each region of the main body.

[0023] Referring to Figures 1 to 3, a multilayer capacitor 100 according to one embodiment of the present invention includes a main body 110 which includes a dielectric layer 111 and a plurality of internal electrodes 121, 122 stacked in a first direction (X direction) with a dielectric layer 111 in between, and external electrodes 131, 132, wherein the average grain size of the dielectric layer 111 is adjusted for each region of the main body 110.

[0024] The main body 110 includes a laminated structure in which multiple dielectric layers 111 are stacked in a first direction (X direction), and can be obtained, for example, by stacking multiple green sheets and then sintering them. Through such a sintering process, the multiple dielectric layers 111 can 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, for example, BT-based, i.e., barium titanate (BaTiO3) based ceramics, but other materials known in the art can also be used as long as sufficient capacitance can be obtained. Along with such ceramic materials as the main component, the dielectric layers 111 may further contain, if necessary, additives, organic solvents, plasticizers, binders, and dispersants. In the case of additives, they may include metal components, which can be added in the form of metal oxides during the manufacturing process. Examples of such metal oxide additives include at least one of the following substances: MnO2, Dy2O3, BaO, MgO, Al2O3, SiO2, Cr2O3, and CaCO3.

[0025] 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 in a third direction (Z direction) opposite to each other on the main body 110, as shown in the embodiment in Figure 2. Here, the third direction (Z direction) can be a direction perpendicular to the first direction (X direction) and the second direction (Y direction), where the direction in which the first surface S1 and the second surface S2 of the active part 112 of the main body 110 face each other is defined as the second direction (Y direction). The first and second internal electrodes 121, 122 can have different polarities when driven in connection with different external electrodes 131, 132, 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 the main constituent materials for the internal electrodes 121 and 122 include nickel (Ni), copper (Cu), palladium (Pd), and silver (Ag), and alloys of these materials can also be used.

[0026] External electrodes 131 and 132 are formed on the outside of 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. In this case, the first and second external electrodes 131 and 132 may be arranged to face each other in the third direction (Z direction). External electrodes 131 and 132 can be formed by methods such as manufacturing a paste containing a conductive metal and then applying it to the main body 110. Examples of conductive metals include nickel (Ni), copper (Cu), palladium (Pd), gold (Au), or alloys thereof. Furthermore, external electrodes 131 and 132 may include a plating layer containing Ni, Sn, etc.

[0027] Referring to FIG. 3, in the case of this embodiment, the main body 110 has a plurality of internal electrodes 121 and 122 positioned to form a capacitance, and an active portion 112 which is the region corresponding to the region between the internal electrodes arranged outermost in the first direction among the plurality of internal electrodes, a cover portion 114 covering the active portion 112 in the first direction (X direction), and a side margin portion 113 covering the active portion 112 in the second direction (Y direction). Here, the dielectric layers 111 included in the side margin portion 113 and the cover portion 114 can have characteristics different from those of the dielectric layer 111 included in the active portion 112 (for example, grain size, ratio of Ba / Ti, etc.), and this is designed by analyzing factors affecting voltage withstand characteristics and the like for different regions of the main body 110. That is, the average grain size of the dielectric layer 111 is different for different regions of the main body 110, and this is adjusted in consideration of characteristics such as voltage withstand and high-temperature reliability.

[0028] Specifically explaining this with reference to FIG. 4, FIG. 4 shows the main body in FIG. 3 subdivided by region, and the internal electrodes are not shown. In the case of this embodiment, when the average grain size of the dielectric layer 111 in the central region of the active portion 112 is A1 and the average grain size of the dielectric layer 111 in the active-cover boundary portion adjacent to the cover portion 114 among the active portion 112 is A2, the condition of 1.49 < A1 / A2 < 2.50 is satisfied. Here, as described above, the active portion 112 in the main body 110 can be defined as the region corresponding to the region between the internal electrodes 121 and 122 arranged outermost in the first direction (X direction), and the cover portion 114 can be defined as the region from the region in contact with the outermost internal electrodes 121 and 122 to the surface of the main body 110.

[0029] When the condition of 1.49 < A1 / A2 < 2.50 is satisfied as in this embodiment, sufficient capacitance can be ensured and the breakdown voltage characteristics can also be improved. This is achieved by making the grain growth rates different between the active part 112 and the active-cover boundary part. In the active part 112, sufficient capacitance is ensured, while in the active-cover boundary part, the breakdown voltage characteristics are improved through relatively refined and uniform grains. As can be seen from the experimental results described later, when A1 / A2 is greater than 1.49 compared to when A1 / A2 is 1.49 or less, it can represent the results of improved capacitance and breakdown voltage reliability. However, when A1 / A2 becomes large and reaches a level of 2.50 or more, and the deviation of grain size by region becomes too large, there is a risk that capacitance characteristics and the like will deteriorate.

[0030] Separate from such a condition of 1.49 < A1 / A2 < 2.50, when the average grain size of the dielectric layer 111 in the active-side boundary part adjacent to the side margin part 113 in the active part 112 is defined as A3, the condition of 1.14 ≤ A1 / A3 < 1.50 is satisfied. As can be seen from the experimental examples described later, when A1 / A3 is 1.14 or more compared to when A1 / A3 is less than 1.14, it can represent the results of improved capacitance and breakdown voltage reliability. However, when A1 / A3 becomes large and reaches a level of 1.50 or more, and the deviation of grain size by region becomes too large, there is a risk that capacitance characteristics and the like will deteriorate. Thus, in this embodiment, the grains of the dielectric layer 111 in the central region of the active part 112 are sufficiently grain-grown so that the average grain size becomes relatively large, whereby the capacitance characteristics can be improved. Different from this, in the side margin part 113 and the cover part 114, grain growth is relatively suppressed and the grain size is small. In this case, the condition of 1.49 < A1 / A2 < 2.50 and the condition of 1.14 ≤ A1 / A3 < 1.50 can be satisfied simultaneously.

[0031] Referring to Figures 5 through 9 along with Figure 4, as an example of a method for measuring grain size, the average grain size of the dielectric layer 111 can be measured using the cross-sections obtained by cutting in the first direction (X direction) and the second direction (Y direction), that is, the cross-section of the main body 110 perpendicular to the third direction (Z direction), as a reference. In this case, the third direction (Z direction) can be the plane obtained by cutting in the middle of the main body 110, and the average grain size can be obtained by using an image of this cut plane taken with an electron microscope such as SEM or TEM.

[0032] First, in the case of A1, which is the average grain size of the dielectric layer 111 in the central region of the active part 112, the above cross-section is rectangular R A1 This can be the average size of grain G1 present in rectangle A1, where A1 rectangle R A1 When the length of the active portion 112 in the first direction (X direction) is TA and the length of the active portion 112 in the second direction (Y direction) is WA, the horizontal length is WA / 3 and the vertical length is TA / 3, and the active portion 112 can be symmetrical with respect to the center lines L1 and L2 in the first direction (X direction) and the second direction (Y direction). Furthermore, A2, which is the average grain size of the dielectric layer 111 at the active-cover boundary portion adjacent to the cover portion 114 of the active portion 112, is the rectangular A2 R of the above cross-section. A2 This can be the average size of grain G2 present in rectangle A2, where A2 rectangle R A2 It has a horizontal length of WA / 3 and a vertical length of TA / 6, is symmetrical with respect to the center line L1 in the first direction (X direction) in the active part 112, and can contact the outermost of the multiple internal electrodes 121, 122 in the first direction (X direction). A3 is the A3 rectangle R in the above cross-section. A3 This can be the average size of grain G3 present in A3 rectangle R A3It has a horizontal length of WA / 4 and a vertical length of TA / 3, is symmetric with respect to the center line L2 in the second direction in the active portion 112, and can be in contact with the side margin portion 113. When measuring the sizes of grains G1, G2, and G3, methods such as measuring the areas of grains G1, G2, and G3 and converting them into equivalent circle diameters, or measuring the major axis and the reduced length and calculating the average can be used. Also, in order to improve the measurement accuracy, the above reference rectangle R A1 , R A2 , R A3 can select only grains G1, G2, and G3 whose entire regions are surrounded by grain boundaries. Such a measurement method can also be applied to other grains G4, G6.

[0033] The inventors of the present invention have found that when at least one of the conditions of the average grain size by region of the dielectric layer 111 described above, that is, the condition of 1.49 < A1 / A2 < 2.5 and the condition of 1.14 ≦ A1 / A3 < 1.50 is satisfied, characteristics that can be reliability criteria for laminated capacitors, such as withstand voltage characteristics, are improved, and it has been confirmed that the grain size relationship in the central region, the active-cover boundary portion, and the active-side boundary portion of the active portion 112 is an important parameter that affects such characteristics. More detailed matters related to this will be described later.

[0034] As a more specific grain size condition, when the average grain size of the dielectric layer 111 in the central region of the cover portion 114 is C1 and the average grain size of the dielectric layer 111 in the central region of the side margin portion 113 is M1, the condition C1 < M1 can be satisfied. That is, in the present embodiment, a structure is adopted in which the average grain size of the dielectric layer 111 in the central region of the cover portion 114 is smaller than that in the central region of the side margin portion 113. Through this, the moisture resistance reliability of the cover portion 114 can be further improved. In this case, when the average grain size of the dielectric layer 111 at the cover-active boundary portion adjacent to the active portion 112 in the cover portion 114 is C2, the condition 0.9 < C2 / M1 < 1.1 can be satisfied. This means that the microstructure of the dielectric layer 111 is generally uniform at the central region of the side margin portion 113 and the cover-active boundary portion adjacent to the active portion 112 in the cover portion 114.

[0035] As an example of the measurement criteria for C1, C2, and M1, first, when the length of the cover portion 114 in the first direction (X direction) is TC, C1 can be the average size of the grains G4 existing in the C1 rectangle R C1 in the above cross-section. Here, the C1 rectangle R C1 has a horizontal length of WA / 3 and a vertical length of TC / 3, and can be symmetric with respect to the center lines L1 and L3 in the first and second directions in the cover portion 114. Also, when the length of the side margin portion 113 in the second direction (Y direction) is WM, M1 can be the average size of the grains existing in the M1 rectangle R M1 in the above cross-section. Here, the M1 rectangle R M1 has a horizontal length of WM / 3 and a vertical length of TA / 3, and can be symmetric with respect to the center lines L1 and L4 in the first and second directions in the side margin portion 113. Also, C2 can be the average size of the grains G6 existing in the C2 rectangle R C2 in the above cross-section. Here, the C2 rectangle R C2It has a horizontal length of WA / 3 and a vertical length of TC / 6, is symmetrical with respect to the center line L1 in the first direction in the cover portion 114, and can contact the outermost of the multiple internal electrodes 121, 122 in the first direction (X direction). In this case, M1 and C2 can be at similar levels, and M1 rectangle R M1 The grain present is C2 rectangle R C2 The size of grain G6 can be similar. However, M1 and C2 do not necessarily have to be identical, and as shown in Figure 9, G5 and G6 do not necessarily have to be identical in form.

[0036] To achieve the dielectric grain size conditions described above, the following method can be used as an example. That is, when manufacturing a ceramic green sheet by mixing ceramic powder, binder, solvent, etc. to form the main body 110, a method can be used to adjust the particle size distribution of ceramic particles, binder content, Ba / Ti value (i.e., molar ratio of Ba to Ti) in the active portion 112, side margin portion 113, and cover portion 114. If the binder content ratio in the sheet for forming the side margin portion 113 and cover portion 114 is lower than that in the sheet for forming the active portion 112, or if the Ba / Ti value is increased, shrinkage will occur first in the sheet for forming the side margin portion 113 and cover portion 114 during firing. In this case, the shrinkage rate of the side margin portion 113 and cover portion 114 is faster in the central region than at the boundary, whereas in the active portion 112, the boundary is faster than the central region. As a result, the grain size in the dielectric layer 111 of the side margin portion 113 and cover portion 114 becomes relatively smaller. After the firing process, the binder is hardly detectable in the active portion 112, side margin portion 113, and cover portion 114, so it is not possible to compare the content, but the Ba / Ti value conditions can be the same as during the manufacturing process. That is, the molar ratio of Ba to Ti in the dielectric layer 111 in the central region of the active portion 112 may be smaller than the molar ratio of Ba to Ti in the dielectric layer 111 in the central region of the cover portion 114. Also, the molar ratio of Ba to Ti in the dielectric layer 111 in the central region of the side margin portion 113 may be smaller than the molar ratio of Ba to Ti in the dielectric layer 111 in the central region of the cover portion 114, and larger than the molar ratio of Ba to Ti in the dielectric layer 111 in the central region of the active portion 112.

[0037] On the other hand, the particle size distribution of the ceramic particles can also affect the grain size of the dielectric layer 111 in the active portion 112, side margin portion 113, and cover portion 114 after firing, but according to the inventors' research, it had a less significant effect than the binder content or Ba / Ti value. Therefore, it can be said that in order to obtain the above-mentioned grain size conditions in this embodiment, it is not necessary to use ceramic particles with an even smaller particle size than those used for the sheet forming the active portion 112 in the sheet forming the side margin portion 113 and cover portion 114.

[0038] Furthermore, in this embodiment, at least one of the multiple dielectric layers 111 can have an average thickness of less than 0.4 μm. The thickness of the dielectric layer 111 can be measured through the image of the cross-section, and the average thickness can be obtained by calculating the average value of the thickness measured at a number of equally spaced points (e.g., 10 points). When the dielectric layer 111 is realized as a thin film with a thickness of less than 0.4 μm, it is suitable for reducing the size of the multilayer capacitor 100 and improving its capacitance, but there is a risk that the dielectric breakdown characteristics of the dielectric layer 111 will deteriorate. However, if the above-mentioned grain size conditions proposed in this embodiment are met, excellent dielectric breakdown characteristics can be ensured by adjusting the grain size for each region.

[0039] The inventors of this invention prepared samples with different average grain sizes in the active section, side margin section, and cover section, measured the average grain size and its proportion in each region, and conducted capacitance and breakdown voltage (BV) experiments for each sample. Table 1 shows the experimental results, with grain size in nm. Samples 1 and 2 correspond to embodiments of the present invention, while samples 3 to 11 correspond to comparative examples that do not satisfy either the A1 / A2 condition or the A1 / A3 condition.

[0040] [Table 1]

[0041] According to the above experimental results, when the condition of 1.49 < A1 / A2 < 2.50 was satisfied, the capacitance was high as a level exceeding 4.7 μF, and at the same time, the withstand voltage characteristics were relatively excellent. Similarly, when the condition of 1.14 ≤ A1 / A3 < 1.50 was satisfied, the capacitance and the withstand voltage characteristics were excellent. This is because in the active part, the grain growth of the dielectric layer was sufficiently carried out to ensure sufficient capacitance, while in the cover part and the side margin part, the dielectric layer had a relatively dense structure with uniform grain size, resulting in improved reliability. In addition to such conditions, when 0.9 < C2 / M1 < 1.1 was satisfied and the difference in grain size between the cover-active boundary part and the side margin part was not large, it was advantageous in terms of capacitance and withstand voltage characteristics. Here, although the result value for C1 is not presented, in the embodiments of the present invention, the condition of C1 < M1 was satisfied, which means that the average grain size of the dielectric layer was larger in the central region of the side margin part than in the central region of the cover part.

[0042] The present invention is not limited by the above-described embodiments and the accompanying drawings, but is limited by the appended claims. Therefore, it is obvious to those having ordinary knowledge in the art that various forms of substitution, modification, and change are possible within the scope not departing from the technical idea of the present invention described in the appended claims, and this also belongs to the technical idea described in the appended claims.

Explanation of Reference Numerals

[0043] 100: Multilayer capacitor 110: Body 111: Dielectric layer 112: Active part 113: Side margin part 114: Cover part 121, 122: Internal electrodes 131, 132: External electrodes

Claims

1. A body including multiple dielectric layers and multiple internal electrodes stacked in a first direction with the multiple dielectric layers in between, The body comprises an external electrode formed on the outside of the main body and connected to the plurality of internal electrodes, The main body includes an active portion which is the region between the outermost internal electrodes of the plurality of internal electrodes located in the first direction, where the plurality of internal electrodes are positioned to form a capacitance, a cover portion which covers the active portion in the first direction, and a side margin portion which covers the active portion in a second direction perpendicular to the first direction. When A1 is the average grain size of the plurality of dielectric layers in the central region of the active portion, and A2 is the average grain size of the plurality of dielectric layers in the active-cover boundary portion adjacent to the cover portion of the active portion, The condition 1.49 < A1 / A2 < 2.50 is satisfied, Let C1 be the average grain size of the plurality of dielectric layers in the central region of the cover portion. When the average grain size of the plurality of dielectric layers in the central region of the side margin is M1, A multilayer capacitor that satisfies the condition C1 < M1.

2. When the direction perpendicular to the first and second directions is defined as the third direction, the cross-section of the main body perpendicular to the third direction is used as a reference. Let the length of the active portion in the first direction be TA. When the length of the active portion in the second direction is WA, The stacked capacitor according to claim 1, wherein A1 is the average size of grains present in the A1 rectangle of the cross-section, the A1 rectangle has a horizontal length of WA / 3 and a vertical length of TA / 3, and is symmetrical in the active portion with respect to the center lines of the first and second directions.

3. The stacked capacitor according to claim 2, wherein A2 is the average size of grains present in the A2 rectangle of the cross-section, the A2 rectangle has a horizontal length of WA / 3 and a vertical length of TA / 6, is symmetrical in the active portion with respect to the center line in the first direction, and is in contact with the outermost internal electrode among the plurality of internal electrodes arranged in the first direction.

4. When the direction perpendicular to the first and second directions is defined as the third direction, the cross-section of the main body perpendicular to the third direction is used as a reference. When the length of the cover portion in the first direction is TC, The stacked capacitor according to any one of claims 1 to 3, wherein C1 is the average size of grains present in the C1 rectangle of the cross-section, the C1 rectangle has a horizontal length of WA / 3 and a vertical length of TC / 3, and is symmetrical in the cover portion with respect to the center lines in the first and second directions.

5. When the length of the side margin portion in the second direction is WM, The stacked capacitor according to any one of claims 1 to 4, wherein M1 is the average size of grains present in the M1 rectangle in the cross-section of the main body perpendicular to the third direction perpendicular to the first and second directions, the M1 rectangle having a horizontal length of WM / 3 and a vertical length of TA / 3, and is symmetrical in the side margin portion with respect to the center lines of the first and second directions.

6. When C2 is the average grain size of the plurality of dielectric layers in the cover-active boundary portion adjacent to the active portion of the cover portion, A multilayer capacitor according to any one of claims 1 to 5, satisfying the condition 0.9 < C2 / M1 < 1.

1.

7. When the length of the cover portion in the first direction is TC, The stacked capacitor according to claim 6, wherein C2 is the average size of grains present in the C2 rectangle in the cross-section of the main body perpendicular to the third direction perpendicular to the first and second directions, the C2 rectangle has a horizontal length of WA / 3 and a vertical length of TC / 6, is symmetrical with respect to the center line in the first direction in the cover portion, and is in contact with the outermost internal electrode in the first direction among the plurality of internal electrodes.

8. The plurality of dielectric layers include a barium titanate component, The multilayer capacitor according to claim 1, wherein the molar ratio of Ba to Ti in the plurality of dielectric layers in the central region of the active portion is smaller than the molar ratio of Ba to Ti in the plurality of dielectric layers in the central region of the cover portion.

9. A body including multiple dielectric layers and multiple internal electrodes stacked in a first direction with the multiple dielectric layers in between, The body comprises an external electrode formed on the outside of the main body and connected to the plurality of internal electrodes, The main body includes an active portion which is the region between the outermost internal electrodes of the plurality of internal electrodes located in the first direction, where the plurality of internal electrodes are positioned to form a capacitance, a cover portion which covers the active portion in the first direction, and a side margin portion which covers the active portion in a second direction perpendicular to the first direction. When A1 is the average grain size of the plurality of dielectric layers in the central region of the active portion, and A2 is the average grain size of the plurality of dielectric layers in the active-cover boundary portion adjacent to the cover portion of the active portion, The condition 1.49 < A1 / A2 < 2.50 is satisfied, A multilayer capacitor in which the molar ratio of Ba to Ti in the plurality of dielectric layers in the central region of the side margin is smaller than the molar ratio of Ba to Ti in the plurality of dielectric layers in the central region of the cover, and larger than the molar ratio of Ba to Ti in the plurality of dielectric layers in the central region of the active.

10. A multilayer capacitor according to any one of claims 1 to 9, wherein at least one of the plurality of dielectric layers has an average thickness of less than 0.4 μm.

11. A body including multiple dielectric layers and multiple internal electrodes stacked in a first direction with the multiple dielectric layers in between, The body includes an external electrode formed on the outside of the main body and connected to the plurality of internal electrodes, The main body includes an active portion which is the region between the outermost internal electrodes of the plurality of internal electrodes located in the first direction, where the plurality of internal electrodes are positioned to form a capacitance, a cover portion which covers the active portion in the first direction, and a side margin portion which covers the active portion in a second direction perpendicular to the first direction. When A1 is the average grain size of the plurality of dielectric layers in the central region of the active portion, and A3 is the average grain size of the plurality of dielectric layers in the active-side boundary portion adjacent to the side margin portion of the active portion, A multilayer capacitor that satisfies the condition 1.14 ≤ A1 / A3 < 1.

21.

12. When the direction perpendicular to the first and second directions is defined as the third direction, the cross-section of the main body perpendicular to the third direction is used as a reference. Let the length of the active portion in the first direction be TA. When the length of the active portion in the second direction is WA, The stacked capacitor according to claim 11, wherein A1 is the average size of grains present in the A1 rectangle of the cross-section, the A1 rectangle has a horizontal length of WA / 3 and a vertical length of TA / 3, and is symmetrical in the active portion with respect to the center lines of the first and second directions.

13. The stacked capacitor according to claim 12, wherein A3 is the average size of grains present in the A3 rectangle of the cross-section, the A3 rectangle has a horizontal length of WA / 4 and a vertical length of TA / 3, is symmetrical in the active portion with respect to the center line in the second direction, and is in contact with the side margin portion.

14. Let C1 be the average grain size of the plurality of dielectric layers in the central region of the cover portion. When the average grain size of the plurality of dielectric layers in the central region of the side margin is M1, A multilayer capacitor according to any one of claims 11 to 13, satisfying the condition C1 < M1.

15. When the direction perpendicular to the first and second directions is defined as the third direction, the cross-section of the main body perpendicular to the third direction is used as a reference. When the length of the cover portion in the first direction is TC, The stacked capacitor according to claim 14, wherein C1 is the average size of grains present in the C1 rectangle of the cross-section, the C1 rectangle has a horizontal length of WA / 3 and a vertical length of TC / 3, and is symmetrical in the cover portion with respect to the center lines in the first and second directions.

16. When the length of the side margin portion in the second direction is WM, The multilayer capacitor according to claim 14 or 15, wherein M1 is the average size of grains present in the M1 rectangle in the cross-section of the main body perpendicular to the third direction perpendicular to the first and second directions, the M1 rectangle having a horizontal length of WM / 3 and a vertical length of TA / 3, and is symmetrical in the side margin portion with respect to the center lines of the first and second directions.

17. When the average grain size of the plurality of dielectric layers in the cover-active boundary portion adjacent to the active portion of the cover portion is C2, A multilayer capacitor according to any one of claims 14 to 16, satisfying the condition 0.9 < C2 / M1 < 1.

1.

18. When the length of the cover portion in the first direction is TC, The stacked capacitor according to claim 17, wherein C2 is the average size of grains present in the C2 rectangle in the cross-section of the main body perpendicular to the third direction perpendicular to the first and second directions, the C2 rectangle has a horizontal length of WA / 3 and a vertical length of TC / 6, is symmetrical with respect to the center line in the first direction in the cover portion, and is in contact with the outermost internal electrode in the first direction among the plurality of internal electrodes.

19. A multilayer capacitor according to any one of claims 11 to 18, wherein at least one of the plurality of dielectric layers has an average thickness of less than 0.4 μm.

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