Multilayer capacitors

Abstract

This invention provides a multilayer capacitor comprising a capacitor body having an effective region, an upper cover region, and a lower cover region, as well as wide edges on opposite sides of the effective region. The wide edges include a first region adjacent to a first inner electrode and a second inner electrode on its inner side, and a second region on its outer side between the first region and a corresponding outer surface of the capacitor body. The upper cover region and the lower cover region each include a third region adjacent to the inner electrode on its inner side, and a fourth region on its outer side between the third region and a corresponding outer surface of the capacitor body. The effective region, the second region, and the fourth region have the same dielectric constant A, and the first region and the third region have the same dielectric constant B, wherein A and B are different from each other and satisfy 0.483 ≤ B / A.

Description

[0001] This application is a divisional application of the invention patent application filed on April 16, 2020, with application number 202010299955.7, entitled "Multilayer capacitor and substrate on which multilayer capacitor is mounted". Technical Field

[0002] This disclosure relates to a multilayer capacitor and a substrate on which the multilayer capacitor is mounted. Background Technology

[0003] Electronic components using ceramic materials can include capacitors, inductors, piezoelectric elements, varistors, thermistors, etc.

[0004] Among the components described above, multilayer capacitors can be used in various types of electronic devices because they can have a small size and achieve high capacitance.

[0005] Recently, multilayer capacitors have been increasingly used in vehicle and IT products, and multilayer capacitors used in vehicle products may require high reliability for use in harsh driving environments.

[0006] A multilayer capacitor may include a capacitor body formed of ceramic material, an inner electrode disposed in the capacitor body, and an outer electrode mounted on the surface of the capacitor body and connected to the inner electrode.

[0007] To reduce the size of multilayer capacitors, techniques have been used to reduce their thickness. However, when the thickness of a multilayer capacitor is reduced, a strong electric field is generated at the ends of the internal electrodes when a voltage is applied. This concentration of the electric field can cause insulation breakdown (one of the defects of multilayer capacitors) and reduce reliability.

[0008] Therefore, it is necessary to ensure high capacitance and reduce the electric field concentrated at the end of the internal electrode. Summary of the Invention

[0009] One aspect of this disclosure is to provide a multilayer capacitor that can have increased capacitance by increasing the area of ​​the inner electrodes and can reduce the concentration of electric field at the interface surface between the effective region and the edge of the capacitor body at the end of the exposed inner electrodes.

[0010] According to one aspect of this disclosure, a multilayer capacitor includes: a capacitor body comprising alternately disposed first and second inner electrodes and a dielectric layer between the first and second inner electrodes, and having a first and second surface opposite to each other, a third and fourth surface connected to the first and second surfaces and opposite to each other, and a fifth and sixth surface connected to the first and second surfaces and connected to the third and fourth surfaces and opposite to each other. The first inner electrode is exposed through the third surface, and the second inner electrode is exposed through the fourth surface. A first and second outer electrode are disposed on the third and fourth surfaces, respectively, and are connected to the first and second inner electrodes, respectively. The capacitor body further includes an effective region, an upper cover region, and a lower cover region, wherein the first and second inner electrodes are alternately disposed in the effective region and the dielectric layer is between the first and second inner electrodes, and the upper cover region and the lower cover region are respectively disposed above the uppermost inner electrode and below the lowermost inner electrode in the stacking direction of the first and second inner electrodes. The wide edges of the capacitor body do not have the first inner electrode and the second inner electrode, and are disposed on opposite sides of the effective region in the direction connecting the fifth surface and the sixth surface to each other. Each wide edge includes a first region disposed on its inner side adjacent to the first inner electrode and the second inner electrode, and a second region disposed on its outer side between the first region and the corresponding outer surface of the capacitor body. The upper cover region and the lower cover region each include a third region disposed on its inner side adjacent to the first inner electrode or the second inner electrode, and a fourth region disposed on its outer side between the third region and the corresponding outer surface of the capacitor body. The effective region, the second region, and the fourth region have the same dielectric constant A, and the first region and the third region have the same dielectric constant B, and A and B are different from each other and satisfy 0.5 ≤ B / A.

[0011] A and B satisfy 0.937≤B / A.

[0012] When the average thickness of the dielectric layer is defined as C, the average thickness of the first inner electrode or the average thickness of the second inner electrode is defined as D, and the average width of the first region or the average width of the third region is defined as E, E can satisfy C≤E and D≤E.

[0013] The grain size of the effective region, the grain size of the second region, and the grain size of the fourth region may be larger than the grain size of the first region and the grain size of the third region.

[0014] The average thickness of the first inner electrode and the average thickness of the second inner electrode can be 0.4 μm or less.

[0015] The average thickness of the dielectric layer can be greater than 0.5 μm.

[0016] The first external electrode may include a corresponding first connecting portion and a corresponding first strip portion. The first connecting portion is disposed on the third surface of the capacitor body and connected to the first internal electrode. The first strip portion extends from the first connecting portion to a corresponding portion of the first surface of the capacitor body. The second external electrode may include a corresponding second connecting portion and a corresponding second strip portion. The second connecting portion is disposed on the fourth surface of the capacitor body and connected to the second internal electrode. The second strip portion extends from the second connecting portion to a corresponding portion of the first surface of the capacitor body.

[0017] According to one aspect of this disclosure, a substrate on which a multilayer capacitor is mounted includes a substrate and a multilayer capacitor mounted thereon, the substrate having a first electrode pad and a second electrode pad on one surface of the substrate. A first external electrode and a second external electrode are respectively mounted on the first electrode pad and the second electrode pad and respectively connected to the first electrode pad and the second electrode pad.

[0018] According to another aspect of this disclosure, a multilayer capacitor includes: a capacitor body comprising a dielectric material and having internal electrodes, the internal electrodes including alternately disposed first internal electrodes and second internal electrodes, and a dielectric layer between the first internal electrodes and the second internal electrodes. A first external electrode and a second external electrode are disposed on the outer surface of the capacitor body and respectively connected to the first internal electrode and the second internal electrode. The average thickness of the first internal electrode and the average thickness of the second internal electrode are 0.4 μm or less, and the dielectric constant A of the dielectric layer in the region between the first internal electrode and the second internal electrode is different from the dielectric constant B of the dielectric material of the capacitor body in the region disposed between the internal electrodes and the outer surface of the capacitor body.

[0019] According to another aspect of this disclosure, a multilayer capacitor includes: a capacitor body comprising a dielectric material and having internal electrodes, the internal electrodes comprising alternately disposed first internal electrodes and second internal electrodes, and a dielectric layer between the first internal electrodes and the second internal electrodes. A first external electrode and a second external electrode are disposed on the outer surface of the capacitor body and respectively connected to the first internal electrode and the second internal electrode. The average thickness of the first internal electrode and the average thickness of the second internal electrode are 0.4 μm or less, and the dielectric constant B of the dielectric material of the capacitor body in a first region disposed between the internal electrodes and the outer surface of the capacitor body is different from the dielectric constant A of the dielectric material of the capacitor body in a second region disposed between the first region and the outer surface of the capacitor body.

[0020] According to another aspect of this disclosure, a multilayer capacitor includes: a capacitor body comprising a dielectric material and having internal electrodes, the internal electrodes including a first internal electrode and a second internal electrode, and a dielectric layer between the first internal electrode and the second internal electrode. A first external electrode and a second external electrode are disposed on the outer surface of the capacitor body and respectively connected to the first internal electrode and the second internal electrode. The dielectric constant B of the dielectric material in a first region of the capacitor body disposed between the internal electrodes and the outer surface of the capacitor body is different from the dielectric constant A of the dielectric material in a second region of the capacitor body disposed between the first region and the outer surface of the capacitor body, and the average width E of the first region and the average thickness C of the dielectric layer between the internal electrodes satisfy C ≤ E. Attached Figure Description

[0021] The above and other aspects, features and advantages of this disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0022] Figure 1 This is a perspective view showing a multilayer capacitor according to an exemplary embodiment of the present disclosure;

[0023] Figure 2A It is along Figure 1 A cross-sectional view taken from line I-I' in the diagram;

[0024] Figure 2B It is along Figure 1 A cross-sectional view of an alternative embodiment of the multilayer capacitor of this disclosure, taken by line I-I';

[0025] Figure 3 It is along Figure 1 A cross-sectional view taken from line II-II' in the diagram;

[0026] Figure 4A and Figure 4B They are shown respectively Figure 1 The first internal electrode of the multilayer capacitor shown is illustrated. Figure 1 A cross-sectional view of the structure of the second internal electrode of the multilayer capacitor shown;

[0027] Figure 5 It is a graph showing the average electric field as a function of B / A; and

[0028] Figure 6 It shows that it is equipped with Figure 3 The image shows a cross-sectional view of the substrate of the multilayer capacitor. Detailed Implementation

[0029] In the following description, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0030] However, this disclosure may be exemplified in many different forms and should not be construed as being limited to the specific embodiments set forth herein.

[0031] Specifically, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0032] Accordingly, for clarity of description, the shape and size of the elements in the figures may be exaggerated, and the elements indicated by the same reference numerals are the same elements in the figures.

[0033] Furthermore, throughout the specification, it will be understood that when a part "includes" an element, it may further include other elements without excluding them, unless otherwise specifically stated.

[0034] In the attached figures, the X, Y, and Z directions can represent the length, width, and thickness directions of the multilayer capacitor, respectively.

[0035] The Z-direction can be the same as the stacking direction of the dielectric layers or the stacking direction of the dielectric layer stack.

[0036] Figure 1 This is a perspective view showing a multilayer capacitor according to an example embodiment. Figure 2A It is along Figure 1 The cross-sectional view taken from line I-I' in the diagram. Figure 3 It is along Figure 1 The cross-sectional view taken from line II-II' in the diagram. Figure 4A and Figure 4B They are shown in Figure 1 A cross-sectional view of the structure of the first internal electrode used in the multilayer capacitor shown, and in Figure 1 A cross-sectional view of the structure of the second internal electrode used in the multilayer capacitor shown.

[0037] In the following description, reference will be made to Figure 1 , Figure 2A , Figure 3 , Figure 4A and Figure 4B Describe the multilayer capacitor in the example embodiment.

[0038] Reference Figure 1 , Figure 2A , Figure 3 , Figure 4A and Figure 4B The multilayer capacitor 100 in the example embodiment may include a capacitor body 110 and a first external electrode 131 and a second external electrode 132.

[0039] The capacitor body 110 may include an effective region 115, an upper cover region 112, and a lower cover region 113. The effective region 115 may correspond to the region in which a first inner electrode 121 and a second inner electrode 122 are stacked and form a capacitor. The upper cover region 112 and the lower cover region 113 may be outside the effective region and may include a region above the uppermost inner electrode 121 of the effective region 115 and a region below the lowermost inner electrode 122 of the effective region 115.

[0040] The upper cover region 112 and the lower cover region 113 can be divided into a third region on their inner sides adjacent to the effective region 115 and the inner electrodes 121 and 122, and a fourth region on their outer sides in contact with the outer surface of the capacitor body 110. For example, in Figure 2A In the middle, the third region corresponds to the upper and lower parts of the region with dielectric constant "B", and the fourth region corresponds to the upper and lower parts of the outer / peripheral region with dielectric constant "A".

[0041] Note that in some embodiments, the upper cover region 112 and the lower cover region 113 may include only the third region and may not include the fourth region. In such embodiments, the third region may include the entire upper cover region and the entire lower cover region, such that the upper cover region 112 may extend integrally from the upper surface of the effective region 115 to the upper surface of the capacitor body 110 and the lower cover region 113 may extend integrally from the lower surface of the effective region 115 to the lower surface of the capacitor body 110.

[0042] The edge obtained in the Y direction outside and adjacent to the effective region 115 can be defined as a width edge, and the width edge can be divided into a first region on its inner side adjacent to the edges of the effective region 115 and the inner electrodes 121 and 122, and a second region on its outer side contacting the outer surface of the capacitor body 110. For example, in Figure 2AIn the first region, the left and right sides of the region with dielectric constant "B" correspond to each other, and the second region corresponds to the left and right sides of the outer / peripheral region with dielectric constant "A".

[0043] Note that in some embodiments, such as Figure 2B In the illustrated embodiment, the width edge may include only the first region and may not include the second region. In such an embodiment, the first region may extend across the entire width of the width edge. Thus, the first region may include the entire width edge, such that the left width edge may extend integrally from the left surface of the effective region 115 to the left outer surface of the capacitor body 110 and the right width edge may extend integrally from the right surface of the effective region 115 to the right outer surface of the capacitor body 110.

[0044] The dielectric constants of effective region 115, the second region, and the fourth region can be the same, and the dielectric constants of the first region and the third region can be the same. Here, the dielectric constant of a region can refer to the dielectric constant of the dielectric layer or dielectric material in the corresponding region.

[0045] When the dielectric constant of the effective region 115, the dielectric constant of the second region, and the dielectric constant of the fourth region are defined as A, and when the dielectric constant of the first region and the dielectric constant of the third region are defined as B, A and B can satisfy 0.5≤B / A.

[0046] The capacitor body 110 can be formed by stacking multiple dielectric layers 111 in the Z direction and sintering the stacked dielectric layers. The boundaries between adjacent dielectric layers 111 of the capacitor body 110 can be integrated, making it difficult to identify the boundaries without using a scanning electron microscope (SEM).

[0047] The capacitor body 110 may include a plurality of dielectric layers 111 and a first inner electrode 121 and a second inner electrode 122 having different polarities and being alternately arranged in the Z direction, with each dielectric layer 111 being located between the first inner electrode 121 and the second inner electrode 122.

[0048] The capacitor body 110 may include an effective region 115 that contributes to the capacitance of the multilayer capacitor 100, an upper cover region 112, and a lower cover region 113. In the effective region 115, a first inner electrode 121 and a second inner electrode 122 are alternately stacked in the Z direction, and a dielectric layer 111 is located between the first inner electrode 121 and the second inner electrode 122. The upper cover region 112 and the lower cover region 113 are respectively disposed as edges on the upper and lower surfaces of the effective region 115 in the Z direction. The upper cover region 112 and the lower cover region 113 may be disposed directly above the uppermost inner electrode and directly below the lowermost inner electrode of the capacitor body 110, respectively, to contact the uppermost and lowermost inner electrodes of the capacitor body 110.

[0049] The shape of the capacitor body 110 is not limited to any particular shape. The capacitor body 110 may have, for example, a hexahedral shape, and may have a first surface 1 and a second surface 2 opposite to each other in the Z direction, a third surface 3 and a fourth surface 4 connected to the first surface 1 and the second surface 2 and opposite to each other in the X direction, and a fifth surface 5 and a sixth surface 6 connected to the first surface 1 and the second surface 2 and connected to the third surface 3 and the fourth surface 4 and opposite to each other in the Y direction. The first surface 1 may be a mounting surface.

[0050] For example, dielectric layer 111 may include ceramic powder, such as BaTiO3-based ceramic powder.

[0051] BaTiO3-based ceramic powder can be made by partially dissolving Ca, Zr, etc. in BaTiO3 (Ba 1-x Ca x TiO3, Ba(Ti 1-y Ca y O3、(Ba 1-x Ca x (Ti) 1-y Zr y O3, Ba(Ti) 1-y Zr y Examples of BaTiO3-based ceramic powders include O3, but examples are not limited to these.

[0052] In addition to ceramic powder, dielectric layer 111 may also include ceramic additives, organic solvents, plasticizers, binders, dispersants, etc.

[0053] Ceramic additives may include, for example, transition metal oxides or transition metal carbides, rare earth elements, magnesium (Mg) or aluminum (Al), etc.

[0054] The average thickness C of dielectric layer 111 can be greater than 0.5 μm.

[0055] When the average thickness C of dielectric layer 111 is 0.5 μm or less, the breakdown voltage (BDV) may decrease.

[0056] The first inner electrode 121 and the second inner electrode 122 may be applied with different polarities, and the first inner electrode 121 and the second inner electrode 122 may be disposed on the dielectric layer 111 and may be stacked in the Z direction. The first inner electrode 121 and the second inner electrode 122 may be alternately disposed in the capacitor body 110 in the Z direction opposite to each other, and a single dielectric layer 111 is located between each pair of adjacent inner electrodes.

[0057] The first inner electrode 121 and the second inner electrode 122 can be electrically insulated from each other by a dielectric layer 111 between the first inner electrode 121 and the second inner electrode 122.

[0058] The first internal electrode 121 can be exposed through the third surface 3 of the capacitor body 110.

[0059] The second internal electrode 122 can be exposed through the fourth surface 4 of the capacitor body 110.

[0060] The ends of the first inner electrode 121 and the second inner electrode 122, which are exposed through the third surface 3 and the fourth surface 4 of the capacitor body 110, respectively, can be electrically connected to the first outer electrode 131 and the second outer electrode 132, which are disposed at opposite ends of the capacitor body 110 in the X direction.

[0061] Therefore, when a certain level of voltage is applied to the first external electrode 131 and the second external electrode 132, charge can accumulate between the first internal electrode 121 and the second internal electrode 122.

[0062] The capacitance of the multilayer capacitor 100 is proportional to the area of ​​overlap between the first inner electrode 121 and the second inner electrode 122 that overlap each other in the Z direction in the effective region 115.

[0063] The materials of the first internal electrode 121 and the second internal electrode 122 are not limited to any particular material. For example, the first internal electrode 121 and the second internal electrode 122 may be formed using a conductive paste containing one or more of noble metals, nickel (Ni) and copper (Cu).

[0064] Screen printing, gravure printing, and other methods can be used to print conductive paste, but examples of methods for forming internal electrodes are not limited to these.

[0065] The average thickness D of the first inner electrode 121 and the second inner electrode 122 can be 0.4 μm or less.

[0066] When the average thickness D of the first inner electrode 121 and the second inner electrode 122 is greater than 0.4 μm, the thickness of the capacitor body 110 will increase, which may make it difficult to realize a high-capacitance multilayer capacitor with a reduced size.

[0067] Voltages of different polarities can be provided to the first external electrode 131 and the second external electrode 132. The first external electrode 131 and the second external electrode 132 can be disposed on opposite ends of the capacitor body 110 in the X direction and cover opposite ends of the capacitor body 110 in the X direction. They can be electrically connected to the exposed portions of the first internal electrode 121 and the second internal electrode 122 that are exposed through the third surface 3 and the fourth surface 4 of the capacitor body 110, respectively.

[0068] The first external electrode 131 may include a first connecting portion 131a and a first strip portion 131b.

[0069] The first connecting part 131a can be disposed on the third surface 3 of the capacitor body 110, and can contact the end of the first inner electrode 121 that is exposed outward through the third surface 3 of the capacitor body 110, and can physically connect and electrically connect the first inner electrode 121 and the first outer electrode 131 to each other.

[0070] The first strip 131b may be a portion extending from the first connection portion 131a to a portion of the first surface 1 of the capacitor body 110.

[0071] If necessary, the first strip 131b may extend further toward and onto the second surface 2, fifth surface 5 and sixth surface 6 of the capacitor body 110 to improve bonding strength and for other purposes.

[0072] The second external electrode 132 may include a second connecting portion 132a and a second strip portion 132b.

[0073] The second connecting portion 132a may be disposed on the fourth surface 4 of the capacitor body 110, and may contact the end of the second inner electrode 122 that is exposed outward through the fourth surface 4 of the capacitor body 110, and may physically connect and electrically connect the second inner electrode 122 and the second outer electrode 132 to each other.

[0074] The second strip 132b may be a portion that extends from the second connecting portion 132a to a portion of the first surface 1 of the capacitor body 110.

[0075] If necessary, the second strip 132b may further extend toward and onto the second surface 2, fifth surface 5 and sixth surface 6 of the capacitor body 110 to improve bonding strength and for other purposes.

[0076] In the example embodiment, when the dielectric constant of the effective region 115 and the dielectric constant of the second and fourth regions of the capacitor body 110 are defined as A and the dielectric constant of the first and third regions of the capacitor body 110 is defined as B, A and B satisfy 0.5 ≤ B / A.

[0077] More preferably, B / A can satisfy 0.937≤B / A.

[0078] In addition, when the average thickness of dielectric layer 111 is defined as C, the average thickness of the first inner electrode 121 or the second inner electrode 122 is defined as D, the average width of the first region or the third region is defined as E, and the average thickness of the width edge is defined as F, E can satisfy C≤E and D≤E.

[0079] When the average width E of the first or third region is smaller than the average thickness C of the dielectric layer 111, the electric field distortion may increase due to the fringing field, and dielectric breakdown is likely to occur in the edge portion obtained in the width direction, as well as in the upper cover region 112 and the lower cover region 113.

[0080] Furthermore, when the average width E of the first region or the third region is smaller than the average thickness D of the first inner electrode 121 or the second inner electrode 122, the electric field distortion may increase due to the edge field, and dielectric breakdown is likely to occur in the edge portion obtained in the width direction as well as in the upper cover region 112 and the lower cover region 113.

[0081] The grain size of the effective region 115, as well as the second and fourth regions, can be larger than the grain size of the first and third regions. For example, the grain size of the dielectric material forming the effective region 115, as well as the second and fourth regions, can be larger than the grain size of the dielectric material forming the first and third regions. In this respect, the average grain size, median grain size, and D of the effective region 115, as well as the first, second, third, and fourth regions... 90 Grain size and other parameters can be used as a measure of its grain size.

[0082] When the medium is a non-magnetic material, electromagnetic waves can propagate inversely proportional to the square root of the dielectric constant on the boundary surface between a medium with a relatively high dielectric constant and a medium with a relatively low dielectric constant.

[0083] The potential pattern on the end of the internal electrode of a multilayer capacitor is a wavy pattern that spreads outward toward the outside of the multilayer capacitor and toward the side with a higher dielectric constant on the boundary surface, and this pattern can be refracted.

[0084] Due to the aforementioned refraction relationship, the electric field can be enhanced in one part and weakened in another. In particular, as the difference in dielectric constant increases, the average electric field value on the interface surface where the effective region and edge of the interface are in contact with each other in the Y and Z directions can decrease.

[0085] Furthermore, the effective area can realize the electrical characteristics (such as capacitance) of a multilayer capacitor, while the width edge and the top and bottom cover areas are not related to the formation of capacitance.

[0086] Therefore, in the multilayer capacitor of the example embodiment, the dielectric constant of the effective region that realizes the effective capacitance can be constructed to be different from the dielectric constant of the edge portion that does not affect the electrical characteristics, and the difference between the dielectric constant A of the effective region 115 and the second and fourth regions on the outer side of the edge portion and the dielectric constant B of the first and third regions on the inner side of the edge portion can be constructed to satisfy 0.5 ≤ B / A.

[0087] As described above, in order to construct regions having corresponding dielectric constants A and B different from each other, the composition of the dielectric material of the effective region 115 where the inner electrode is provided can be constructed to be different from the composition of the dielectric material inside the edge portion obtained in the width direction and the composition of the dielectric material inside the cover region adjacent to the effective region.

[0088] For example, the difference in dielectric constant can be generated by adjusting the auxiliary components contained in the dielectric material included in the effective region 115 of the inner electrode and the auxiliary components contained in the dielectric material included in the interior of the edge portion obtained in the width direction and the interior of the cover region adjacent to the effective region.

[0089] Furthermore, the content of auxiliary components contained in the dielectric material in the outer part of the cover region outside the edge portion obtained in the width direction and outside the effective region can be constructed similarly to the content of auxiliary components contained in the effective region where the inner electrode is set, so as to produce a difference in dielectric constant.

[0090] Dielectric breakdown (one of the defects in multilayer capacitors) can be caused by a strong electric field formed at the ends of the internal electrodes.

[0091] In the example embodiment, when A and B satisfy 0.5≤B / A, the concentration of the electric field can be reduced by distributing the electric field on the interface surface near the end of the inner electrode, while reducing the capacitance reduction of the multilayer capacitor.

[0092] Therefore, dielectric breakdown of multilayer capacitors can be prevented, and the reliability of multilayer capacitors can be improved.

[0093] Figure 5 This is a graph showing the average electric field as measured using Ansys Maxwell 2D Simulation based on the change in the B / A value of a multilayer capacitor.

[0094] In the example embodiment, the dielectric constant A of the effective region 115 and the second and fourth regions of the multilayer capacitor is determined to be 3000, B / A is adjusted by changing the dielectric constant B of the first and third regions, and the magnitude of the average electric field at the ends of the inner electrodes of the multilayer capacitor is observed.

[0095] Reference Figure 5 When the value of B / A increases, the average electric field of the multilayer capacitor decreases.

[0096] Referring to a B / A value of 1.0 (at which the dielectric constant A of the effective region, as well as the second and fourth regions, is the same as the dielectric constant B of the first and third regions), the average electric field of the multilayer capacitor increases by only 3% when B / A is 0.5 compared to when B / A is 1.0.

[0097] Table 1 below lists the defect rate based on the variation of B / A obtained through voltage testing.

[0098] The B / A ratio in each sample was varied by changing experimental conditions (such as material bonding, sintering conditions, molar ratio, etc.). The dielectric constants A and B were measured by inversion based on a fundamental experiment that determined the relationship between the measured capacitance and the molar ratio and grain size at the time of measurement.

[0099] [Table 1]

[0100]

[0101] Referring to Table 1, when the value of B / A is less than 0.5, the defect rate of the electric field at the end of the inner electrode is high, about 70%.

[0102] For #2, with a B / A value of 0.5 or higher, the defect rate is reduced to less than 10%, and for #4 and #5, with a B / A value of 0.937 or higher, the defect rate is 0 and no defects are observed.

[0103] Therefore, the preferred range for a B / A with almost no electric field defects can be determined to be 0.5 or higher, and the more preferred range for a B / A with no electric field defects can be 0.937 or higher.

[0104] Reference Figure 6In the example embodiment, the substrate on which the multilayer capacitor is mounted may include a substrate 210 and a multilayer capacitor 100. The substrate 210 has a first electrode pad 221 and a second electrode pad 222 on one surface of the substrate 210. A first external electrode 131 and a second external electrode 132 are mounted on the upper surface of the substrate 210 to be connected to the first electrode pad 221 and the second electrode pad 222, respectively.

[0105] In the example embodiment, the multilayer capacitor 100 can be mounted on the substrate 210 using solder 231 and 232, but the example embodiment is not limited thereto. Conductive paste can be used instead of solder if desired.

[0106] According to the aforementioned example embodiments, by limiting the dielectric constant of the effective region and limiting the ratio of the dielectric constant of the outer edge to the dielectric constant of the inner edge, the concentration of electric field on the interface surface between the effective region and the edge of the capacitor body at the end of the exposed inner electrode can be resolved, thereby preventing dielectric breakdown and improving the reliability of the multilayer capacitor.

[0107] 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: A capacitor body includes a dielectric layer, a first internal electrode, and a second internal electrode. The capacitor body has a first surface and a second surface opposite to each other, a third surface and a fourth surface connected to the first surface and the second surface and opposite to each other, and a fifth surface and a sixth surface connected to the first surface and the second surface and connected to the third surface and the fourth surface and opposite to each other. The first internal electrode is exposed through the third surface, and the second internal electrode is exposed through the fourth surface. The first external electrode and the second external electrode are respectively disposed on the third surface and the fourth surface, and are respectively connected to the first internal electrode and the second internal electrode. The capacitor body further includes an effective region, an upper cover region, and a lower cover region. In the effective region, a first inner electrode and a second inner electrode are alternately disposed, and the dielectric layer is located between the first inner electrode and the second inner electrode. The upper cover region and the lower cover region are respectively disposed on the upper and lower surfaces of the effective region in the stacking direction of the dielectric layer. The capacitor body has wide edges disposed on opposite sides of the effective region in the direction in which the fifth and sixth surfaces connect to each other. Each wide edge includes a first region disposed on its inner side and a second region disposed on its outer side. The upper cover region and the lower cover region each include a third region disposed on its inner side and a fourth region disposed on its outer side. Wherein, the effective region has a dielectric constant A, and the first region and the third region have a dielectric constant B, and Among them, A and B satisfy 0.483≤B / A, and A and B are different.

2. The multilayer capacitor according to claim 1, wherein, A and B satisfy 0.514 ≤ B / A.

3. The multilayer capacitor according to claim 1, wherein, A and B satisfy 0.937 ≤ B / A.

4. The multilayer capacitor according to claim 1, wherein, When the average thickness of the dielectric layer is defined as C, the average thickness of the first inner electrode or the average thickness of the second inner electrode is defined as D, and the average width of the first region or the average width of the third region is defined as E, C, D and E satisfy C ≤ E and D ≤ E.

5. The multilayer capacitor according to claim 1, wherein, The grain size of the effective region, the grain size of the second region, and the grain size of the fourth region are larger than the grain size of the first region and the grain size of the third region.

6. The multilayer capacitor according to claim 1, wherein, The average thickness of the first inner electrode and the average thickness of the second inner electrode are 0.4 μm or less.

7. The multilayer capacitor according to claim 1, wherein, The average thickness of the dielectric layer is greater than 0.5 μm.

8. A multilayer capacitor, comprising: A capacitor body includes a dielectric layer, a first internal electrode, and a second internal electrode. The capacitor body has a first surface and a second surface opposite to each other, a third surface and a fourth surface connected to the first surface and the second surface and opposite to each other, and a fifth surface and a sixth surface connected to the first surface and the second surface and connected to the third surface and the fourth surface and opposite to each other. The first internal electrode is exposed through the third surface, and the second internal electrode is exposed through the fourth surface. The first external electrode and the second external electrode are respectively disposed on the third surface and the fourth surface, and are respectively connected to the first internal electrode and the second internal electrode. The capacitor body further includes an effective region, an upper cover region, and a lower cover region. In the effective region, a first inner electrode and a second inner electrode are alternately disposed, and the dielectric layer is located between the first inner electrode and the second inner electrode. The upper cover region and the lower cover region are respectively disposed on the upper and lower surfaces of the effective region in the stacking direction of the dielectric layer. The capacitor body has wide edges disposed on opposite sides of the effective region in the direction in which the fifth and sixth surfaces connect to each other. Each wide edge includes a first region disposed on its inner side and a second region disposed on its outer side. The upper cover region and the lower cover region each include a third region disposed on its inner side and a fourth region disposed on its outer side. Wherein, the second region and the fourth region have a dielectric constant A, and the first region and the third region have a dielectric constant B, and Among them, A and B satisfy 0.5≤B / A, and A and B are different.

9. The multilayer capacitor according to claim 8, wherein, A and B satisfy 0.514 ≤ B / A.

10. The multilayer capacitor according to claim 8, wherein, In the multilayer capacitor, A and B satisfy 0.937 ≤ B / A.

11. The multilayer capacitor according to claim 8, wherein, In the multilayer capacitor, when the average thickness of the dielectric layer is defined as C, the average thickness of the first inner electrode or the average thickness of the second inner electrode is defined as D, and the average width of the first region or the average width of the third region is defined as E, C, D and E satisfy C ≤ E and D ≤ E.

12. The multilayer capacitor according to claim 8, wherein, In the multilayer capacitor, the grain size of the effective region, the grain size of the second region, and the grain size of the fourth region are larger than the grain size of the first region and the grain size of the third region.

13. The multilayer capacitor according to claim 8, wherein, In the multilayer capacitor, the average thickness of the first inner electrode and the average thickness of the second inner electrode are 0.4 μm or less.

14. The multilayer capacitor according to claim 8, wherein, In the multilayer capacitor, the average thickness of the dielectric layer is greater than 0.5 μm.

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