Multilayer ceramic capacitors

Abstract

The present invention provides a multilayer ceramic capacitor which achieves high moisture resistance reliability by forming a dense dielectric body in an outer layer part of a multilayer body.　The present invention provides a multilayer ceramic capacitor wherein: a dielectric body in a region DW of a lateral surface-side outer layer part has a Ba / (Ti + Zr) content ratio of 0.995 to 1.003, while having an Mg content relative to 100 parts by mole of Ti higher than that of a dielectric body in the central part of an effective part 11 by 0.5 part by mole to 5.0 parts by mole, or an Mn content relative to 100 parts by mole of Ti higher than that of the dielectric body in the central part of the effective part 11 by 0.4 part by mole to 2.0 parts by mole; and a dielectric body in a region DL of an end surface-side outer layer part has a Ba / (Ti + Zr) content ratio of 0.995 to 1.003, while having an Mg content relative to 100 parts by mole of Ti higher than that of the dielectric body in the central part of the effective part 11 by 0.25 part by mole to 2.5 parts by mole, or an Mn content relative to 100 parts by mole of Ti higher than that of the dielectric body in the central part of the effective part 11 by 0.2 part by mole to 1.0 part by mole.

Description

[Technical Field]

[0001] The present invention relates to a multilayer ceramic capacitor. [Background technology]

[0002] Typically, a multilayer ceramic capacitor comprises a laminate including a plurality of stacked dielectric layers and a plurality of internal electrode layers, and external electrodes arranged at predetermined positions of the laminate so as to be electrically connected to the internal electrode layers. The main regions constituting the laminate include an effective portion where the internal electrode layers overlap each other to form a capacitance, outer layer portions (hereinafter referred to as "main surface side outer layer portions") that sandwich this from the stacking direction, outer layer portions (hereinafter referred to as "side surface side outer layer portions") that sandwich this from a width direction that intersects the stacking direction, outer layer portions (hereinafter referred to as "end surface side outer layer portions") that sandwich this from a length direction that intersects the stacking direction and the width direction, and outer layer portions (hereinafter referred to as "corner side outer layer portions") that are arranged at the four corners of the laminate in a planar view so as to connect the side surface side outer layer portions and the end surface side outer layer portions.

[0003] The laminate is formed through a sintering process, and if the sintering conditions are suitable for the effective portion, the above-mentioned outer layer portions are prone to grain growth of the dielectric material and the generation of spaces between the grains. Such grain growth (increased sintered particle size) tends to cause variations in insulation resistance, while the spaces between the grains become paths for moisture to penetrate from the outside. In particular, the spaces generated in the side surface outer layer portions and the end surface outer layer portions form paths for moisture to reach the effective portion, thereby reducing the moisture resistance reliability of the multilayer ceramic capacitor.

[0004] Therefore, there is a need to develop a multilayer ceramic capacitor that prevents moisture from entering from the outside and improves moisture resistance reliability by forming a dense dielectric in a predetermined region such as the outer layer portion on the side surface. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-32833 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a multilayer ceramic capacitor having high moisture resistance reliability by forming a dense dielectric in predetermined regions such as the outer layer portions on the side surfaces that constitute the laminate, thereby preventing the intrusion of moisture from the outside. [Means for solving the problem]

[0007] The present inventors discovered that when the dielectric layers constituting a multilayer ceramic capacitor contain Ba, Ti, and Zr, and Mg or Mn, and the Ba, Ti, and Zr content and the Mg or Mn content in a predetermined region such as a side outer layer portion are adjusted, a dense dielectric is formed and the moisture resistance reliability of the multilayer ceramic capacitor is improved, leading to the completion of the present invention.

[0008] That is, the present invention provides a multilayer ceramic capacitor comprising a laminate including a plurality of laminated dielectric layers and a plurality of internal electrode layers, and external electrodes arranged to be electrically connected to the internal electrode layers, the dielectric layer contains Ba, Ti, Zr, and Mg or Mn; the laminate comprises a first main surface and a second main surface opposed to each other in a lamination direction of the dielectric layers and the internal electrode layers, a first side surface and a second side surface opposed to each other in a width direction which is a direction intersecting both the lamination direction and a length direction in which the internal electrode layers extend to the external electrodes, and a first end surface and a second end surface opposed to each other in a length direction which is a direction intersecting both the lamination direction and the width direction, the external electrodes are disposed on the first end surface and the second end surface, In the laminate, when a region where the internal electrode layers overlap each other when viewed from the stacking direction is defined as an effective portion, opposing regions sandwiching the effective portion in the stacking direction are defined as a first main surface side outer layer portion and a second main surface side outer layer portion, opposing regions sandwiching the effective portion in the width direction are defined as a first side surface side outer layer portion and a second side surface side outer layer portion, and opposing regions sandwiching the effective portion in the length direction are defined as a first end face side outer layer portion and a second end face side outer layer portion, In the center of the length direction of the first side surface side outer layer portion or the second side surface side outer layer portion, the dielectric in the region between the first side surface or the second side surface and the internal electrode layer is The content ratio of Ba, Ti and Zr, Ba / (Ti+Zr), is 0.995 or more and 1.003 or less, a content of Mg relative to 100 molar parts of Ti is 0.5 or more and 5.0 or less by molar parts larger than a content of Mg relative to 100 molar parts of Ti in a dielectric in a central region in the width direction and the length direction of the laminate, or a content of Mn relative to 100 molar parts of Ti is 0.4 or more and 2.0 or less by molar parts larger than a content of Mn relative to 100 molar parts of Ti in an effective portion in the central region in the width direction and the length direction, In the first end face side outer layer portion or the second end face side outer layer portion, the dielectric in the region between the first end face or the second end face and the internal electrode layer is The content ratio of Ba, Ti and Zr, Ba / (Ti+Zr), is 0.995 or more and 1.003 or less, The multilayer ceramic capacitor has an Mg content relative to 100 molar parts of Ti that is 0.25 to 2.5 molar parts higher than the Mg content relative to 100 molar parts of Ti in an effective portion at the center in the width and length directions, or an Mn content relative to 100 molar parts of Ti that is 0.2 to 1.0 molar part higher than the Mn content relative to 100 molar parts of Ti in a dielectric in a region at the center in the width and length directions of the laminate. [Effects of the Invention]

[0009] According to the present invention, a dense dielectric is formed in a predetermined region such as the outer layer portion on the side surface that constitutes the laminate, making it possible to prevent the intrusion of moisture from the outside and provide a multilayer ceramic capacitor with high moisture resistance reliability. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an external perspective view of a multilayer ceramic capacitor according to the present invention; [Figure 2] 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line II shown in FIG. [Figure 3] 2. FIG. 3 is a cross-sectional view of the multilayer ceramic capacitor taken along line II-II shown in FIG. [Figure 4] 3 is a cross-sectional view of the multilayer ceramic capacitor taken along line III-III shown in FIG. 2. [Figure 5] 4 is a cross-sectional view of the multilayer ceramic capacitor taken along line IV-IV shown in FIG. [Figure 6] 3 is a cross-sectional view of the multilayer ceramic capacitor taken along line VV shown in FIG. 2. [Figure 7] 6 is a partially enlarged view of the vicinity of an end in the width direction W of the internal electrode layer shown in FIG. 5. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described. FIG. 1 is a schematic perspective view of a multilayer ceramic capacitor 1 according to an embodiment. FIG. 2 is a cross-sectional view of the multilayer ceramic capacitor 1 taken along line II shown in FIG. 1. FIG. 3 is a cross-sectional view of the multilayer ceramic capacitor 1 taken along line II-II shown in FIG. 2. FIG. 4 is a cross-sectional view of the multilayer ceramic capacitor 1 taken along line III-III shown in FIG. 2. FIG. 5 is a cross-sectional view of the multilayer ceramic capacitor 1 taken along line IV-IV shown in FIG. 1. FIG. 6 is a cross-sectional view of the multilayer ceramic capacitor 1 taken along line VV shown in FIG. 2. FIG. 7 is a partially enlarged view of an end portion of an internal electrode layer in the width direction W shown in FIG. 5. Line II passes through the center of the multilayer ceramic capacitor 1 in the width direction W, which will be described later, and line IV-IV passes through the center of the multilayer ceramic capacitor 1 in the length direction L, which will be described later.

[0012] In the following description, the direction in which a pair of external electrodes 40 are provided will be referred to as the length direction L, and the direction in which the dielectric layers 20 and the internal electrode layers 30 are stacked will be referred to as the stacking direction T. The direction intersecting both the length direction L and the stacking direction T will be referred to as the width direction W. In the embodiment, the length direction L, the stacking direction T, and the width direction W are mutually orthogonal. The cross section shown in FIG. 2 will also be referred to as the LT cross section. The cross sections shown in FIGS. 3 and 4 will also be referred to as the LW cross section. The cross sections shown in FIGS. 5 and 6 will also be referred to as the WT cross section.

[0013] (multilayer ceramic capacitors) The multilayer ceramic capacitor 1 comprises a laminate 10 including a plurality of laminated dielectric layers 20 and a plurality of internal electrode layers 30, and a pair of external electrodes 40 provided on both ends of the laminate 10.

[0014] (Laminate) The laminate 10 has a substantially rectangular parallelepiped shape. The corners and ridges of the laminate 10 are preferably rounded. A corner is a portion where three surfaces of the laminate intersect, and a ridge is a portion where two surfaces of the laminate intersect. The dimension of the laminate 10 in the length direction L is not necessarily longer than the dimension in the width direction W. Furthermore, unevenness may be formed on part or all of the surfaces constituting the laminate 10.

[0015] The dimensions of the laminate 10 are not particularly limited, but if the dimension of the laminate 10 in the length direction L is defined as the L dimension, then the L dimension is preferably 0.2 mm or more and 10 mm or less. If the dimension of the laminate 10 in the stacking direction T is defined as the T dimension, then the T dimension is preferably 0.1 mm or more and 10 mm or less. If the dimension of the laminate 10 in the width direction W is defined as the W dimension, then the W dimension is preferably 0.1 mm or more and 10 mm or less.

[0016] As shown in Figures 1 and 2, the laminate 10 has a first main surface TS1 and a second main surface TS2 facing in the stacking direction T, a first side surface WS1 and a second side surface WS2 facing in the width direction W that intersects with the stacking direction T, and a first end surface LS1 and a second end surface LS2 facing in the length direction L that intersects with the stacking direction T and the width direction W.

[0017] (dielectric layer) The plurality of dielectric layers 20 stacked in the laminate 10 contain a plurality of ceramic particles containing Ba and Ti. The ceramic particles are, for example, represented by the general formula A m These are crystalline particles of a perovskite compound represented by BO3 (A is Ba, B is Ti, and Zr can be contained in addition to Ti, O is oxygen, and m is the molar ratio of A to B).

[0018] The dielectric layer 20 contains a perovskite compound as a main component and Zr as a secondary component. There are no particular restrictions on the form in which Zr is present within the dielectric layer 20. For example, Zr may be present inside crystal particles of the perovskite compound, with the core and shell indistinguishable from each other. Alternatively, the dielectric layer 20 may have a structure in which the ceramic particles are composed of a core made of a perovskite compound containing Ba and Ti and a shell formed by solid-solving Zr around the core.

[0019] The dielectric layer 20 contains a perovskite-type compound as the main component and Mg or Mn as a secondary component. There are no particular restrictions on the form in which Mg or Mn is present in the dielectric layer 20. For example, the Mg or Mn may be dissolved in the crystal grains of the perovskite-type compound, resulting in a structure in which the core and shell are not clearly distinguishable. Alternatively, the dielectric layer 20 may have a structure in which the ceramic particles are composed of a core portion made of a perovskite-type compound containing Ba and Ti and a shell portion formed by solid-solubilizing Mg or Mn around the core portion. Furthermore, RE (Y, La, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb), Si, Ni, V, Al, etc. may be contained in addition to Mg or Mn as a secondary component.

[0020] The thickness of the dielectric layer 20 is preferably 0.5 μm or more and 72 μm or less. The number of laminated dielectric layers 20 is preferably 10 or more and 700 or less. Note that this number of dielectric layers 20 is the total number of the dielectric layers in the effective portion 11 and the dielectric layers in the first principal surface side outer layer portion TG1 and the second principal surface side outer layer portion TG2.

[0021] (Internal electrode layer) The multiple internal electrode layers 30 stacked in the laminate 10 are composed of first internal electrode layers 31 and second internal electrode layers 32. The multiple first internal electrode layers 31 are arranged on the multiple dielectric layers 20. The multiple second internal electrode layers 32 are arranged on the multiple dielectric layers 20. The multiple first internal electrode layers 31 and the multiple second internal electrode layers 32 are arranged alternately in the stacking direction T of the laminate 10.

[0022] The first internal electrode layer 31 has a first opposing portion 31A opposing the second internal electrode layer 32, and a first lead portion 31B led from the first opposing portion 31A to the first end face LS1. The first lead portion 31B is exposed at the first end face LS1.

[0023] The second internal electrode layer 32 has a second opposing portion 32A opposing the first internal electrode layer 31, and a second lead portion 32B led from the second opposing portion 32A to the second end face LS2. The second lead portion 32B is exposed at the second end face LS2.

[0024] The first internal electrode layer 31 and the second internal electrode layer 32 are made of an appropriate conductive material, such as a metal such as Ni, Cu, Ag, Pd, or Au, or an alloy containing at least one of these metals. When an alloy is used, the first internal electrode layer 31 and the second internal electrode layer 32 may be made of, for example, an Ag-Pd alloy.

[0025] The thickness of each of the first internal electrode layers 31 and the second internal electrode layers 32 is preferably, for example, about 0.2 μm or more and 3.0 μm or less. The total number of the first internal electrode layers 31 and the second internal electrode layers 32 is preferably 5 or more and 350 or less.

[0026] (external electrode) The external electrode 40 is composed of a first external electrode 40A and a second external electrode 40B.

[0027] The first external electrode 40A is disposed on the first end face LS1 side. The first external electrode 40A is connected to the first internal electrode layer 31. The first external electrode 40A is disposed on the first end face LS1. However, in addition to the first end face LS1, the first external electrode 40A may also be disposed on at least one of the first main face TS1, the second main face TS2, the first side face WS1, and the second side face WS2. In this embodiment, the first external electrode 40A is disposed on the first end face LS1 as well as on a portion of the first main face TS1, a portion of the second main face TS2, a portion of the first side face WS1, and a portion of the second side face WS2. Note that the first external electrode 40A may be disposed, for example, from the first end face LS1 to either the first main face TS1 or the second main face TS2. That is, the cross-sectional shape of the first external electrode 40A may be L-shaped (not shown).

[0028] The second external electrode 40B is disposed on the second end face LS2 side. The second external electrode 40B is connected to the second internal electrode layer 32. The second external electrode 40B is disposed on the second end face LS2. However, in addition to the second end face LS2, the second external electrode 40B may also be disposed on at least one of the first main face TS1, the second main face TS2, the first side face WS1, and the second side face WS2. In this embodiment, the second external electrode 40B is disposed on the second end face LS2 as well as on a portion of the first main face TS1, a portion of the second main face TS2, a portion of the first side face WS1, and a portion of the second side face WS2. Note that the second external electrode 40B may be disposed, for example, from the second end face LS2 to either the first main face TS1 or the second main face TS2. That is, the cross-sectional shape of the second external electrode 40B may be L-shaped (not shown).

[0029] In the laminate 10, a capacitance is formed by the first opposing portion 31A of the first internal electrode layer 31 and the second opposing portion 32A of the second internal electrode layer 32 facing each other via the dielectric layer 20. Therefore, the function of a capacitor is exerted between the first external electrode 40A connected to the first internal electrode layer 31 and the second external electrode 40B connected to the second internal electrode layer 32.

[0030] The first external electrode 40A and the second external electrode 40B can be formed, for example, by a base electrode layer and a plating layer disposed on the base electrode layer. The base electrode layer is formed by applying a conductive paste containing a metal component and a glass component to the first end face LS1 and the second end face LS2 of the laminate 10, followed by baking. Examples of the metal component contained in the conductive paste include metals such as Cu, Ni, Ag, Pd, and Au, and alloys such as Ag and Pd.

[0031] The plating layer disposed on the base electrode layer contains at least one of metals such as Cu, Ni, Ag, Pd, and Au, or an alloy such as Ag and Pd. The plating layer may have a two-layer structure of, for example, a Ni plating layer and a Sn plating layer. However, the plating layer may be a single layer or multiple layers.

[0032] The laminate 10 has, as regions constituting the laminate 10, an effective portion 11 where the internal electrode layers overlap each other to form a capacitance, a main surface side outer layer portion TG that sandwiches this from the stacking direction T, a side surface side outer layer portion WG that sandwiches it from a width direction W that intersects with the stacking direction T, and an end surface side outer layer portion LG that sandwiches it from a length direction L that intersects with the stacking direction T and the width direction W.

[0033] (effective part) The effective portion 11 is a portion within the laminate 10 where the first opposing portion 31A of the first internal electrode layer 31 and the second opposing portion 32A of the second internal electrode layer 32 face each other via the dielectric layer 20, generating capacitance and essentially functioning as a capacitor.

[0034] As shown in FIG. 2, the laminate 10 has an effective portion 11, and a first main surface side outer layer portion TG1 and a second main surface side outer layer portion TG2 arranged to sandwich the effective portion 11 in the stacking direction T.

[0035] (Outer layer on main surface side) The first main surface side outer layer portion TG1 is located on the first main surface TS1 side of the laminate 10. The first main surface side outer layer portion TG1 can be formed by stacking a plurality of dielectric layers 20 as ceramic layers located between the first main surface TS1 and the internal electrode layer 30 closest to the first main surface TS1. The dielectric layers 20 used in the first main surface side outer layer portion TG1 may be the same as the dielectric layers 20 used in the effective portion 11.

[0036] The second main surface side outer layer portion TG2 is located on the second main surface TS2 side of the laminate 10. The second main surface side outer layer portion TG2 can be formed by stacking a plurality of dielectric layers 20 as ceramic layers located between the second main surface TS2 and the internal electrode layer 30 closest to the second main surface TS2. The dielectric layer 20 used in the second main surface side outer layer portion TG2 may be the same as the dielectric layer 20 used in the effective portion 11.

[0037] (Side side outer layer) The side surface side outer layer portion WG is composed of a first side surface side outer layer portion WG1 and a second side surface side outer layer portion WG2. The first side surface side outer layer portion WG1 is a portion including the dielectric layer 20 located between the effective portion 11 and the first side surface WS1. The second side surface side outer layer portion WG2 is a portion including the dielectric layer 20 located between the effective portion 11 and the second side surface WS2. Figure 5 shows the ranges of the first side surface side outer layer portion WG1 and the second side surface side outer layer portion WG2 in the WT cross section of the multilayer ceramic capacitor. The side surface side outer layer portion WG is also called a W gap or a side gap.

[0038] (Outer layer on end side) The end surface side outer layer portion LG is composed of a first end surface side outer layer portion LG1 and a second end surface side outer layer portion LG2. The first end surface side outer layer portion LG1 is a portion including the dielectric layer 20 located between the effective portion 11 and the first end surface LS1. The second end surface side outer layer portion LG2 is a portion including the dielectric layer 20 located between the effective portion 11 and the second end surface LS2. Figure 2 shows the ranges of the first end surface side outer layer portion LG1 and the second end surface side outer layer portion LG2 in the LT cross section of the multilayer ceramic capacitor. The end surface side outer layer portion LG is also called an L gap or end gap.

[0039] (region) In the first side surface side outer layer portion WG1 or the second side surface side outer layer portion WG2, as shown in Fig. 5, there is a region DW between the first side surface WS1 or the second side surface WS2 and the internal electrode layer 30. This region DW is likely to serve as a path for moisture in the air to reach the internal electrode layer 30 when moisture in the air penetrates into the laminate 10 from the first side surface WS1 or the second side surface WS2 of the laminate 10. In addition, in the first end surface side outer layer portion LG1 or the second end surface side outer layer portion LG2, as shown in Fig. 2, there is a region DL between the first end surface LS1 or the second end surface LS2 and the internal electrode layer 30. This region DL is likely to serve as a path for moisture in the air to reach the internal electrode layer 30 when moisture in the air penetrates into the laminate 10 from the first end surface LS1 or the second end surface LS2 of the laminate 10. Therefore, by increasing the density of the dielectric in the regions DW and DL and reducing the gaps between the grains, it is possible to suppress the penetration of moisture into the internal electrode layer 30 and improve the moisture resistance reliability of the multilayer ceramic capacitor.

[0040] (Moisture resistance reliability) Multilayer ceramic capacitor samples were prepared with different Ba, Ti, and Zr content ratios (Ba / Ti+Zr) in the dielectric in the side outer layer region DW and the end outer layer region DL, and different Mg or Mn contents, and moisture resistance reliability evaluation tests were conducted.

[0041] The content ratio (Ba / Ti+Zr) and the increment of Mg or Mn were measured by elemental analysis of the dielectric in the region DW and the region DL using transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX). The increment of Mg or Mn was measured relative to the dielectric located at the center of the width direction W and length direction L of the effective portion 11, and was calculated by converting the Ti content to 100 molar parts. The content ratio (Ba / Ti+Zr) and the Mg or Mn content in the region DW of the side outer layer portion were measured at the center of the length direction L of the first side outer layer portion WG1 or the second side outer layer portion WG2.

[0042] (Test Method) A humidity load test was conducted on 36 samples at 125°C, 95% relative humidity, 0.1 MPa gauge pressure, and 4V applied voltage. Samples whose logarithmic value of insulation resistance (LogIR) dropped by two digits from the start of the test were judged to have failed. A Weibull plot was created, and samples with an MTTF (mean time to failure) of less than 72 hours were judged to have failed (×), and samples with an MTTF of 72 hours or more were judged to have passed (〇).

[0043] (Densification test method) The edges / sides of the polished surfaces of the LT and LW cross sections were observed under SEM, and the total area of ​​voids relative to the total area of ​​the dielectric was measured within a 10 μm x 10 μm area from the edge of the edge / side, and the porosity was calculated. If the porosity was 3% or less, it was judged as pass (◯), and otherwise it was judged as fail (×).

[0044] (Grain Growth / Sintered Particle Size Test Method) Five samples were broken to expose the edges and sides of the LT and LW cross sections. The samples were heat-treated to clarify the grain boundaries in the dielectric layer. The heat treatment temperature was set to 1000°C, a temperature that did not induce grain growth but made the grain boundaries clear. The exposed grains of the dielectric layer were observed at 20,000x magnification using a scanning electron microscope (SEM). The field of view was an area of ​​6.3 μm x 4.4 μm. 300 grains were randomly selected from the SEM images for each sample, and image analysis was used to determine the area of ​​the inner part of the grain boundary of each grain, from which the circle-equivalent diameter was calculated, which was taken as the sintered particle diameter. Those having a sintered particle diameter D99≦0.5 μm were judged as pass (◯), and other cases were judged as fail (×).

[0045] [Table 1]

[0046] [Table 2]

[0047] As shown in Table 1, when Mg was contained, good moisture resistance reliability results were obtained in Examples 1 to 9. That is, in the center of the length direction L of the first side surface side outer layer portion WG1 or the second side surface side outer layer portion WG2, the dielectric in the region DW between the first side surface WS1 or the second side surface WS2 and the internal electrode layer 30 has a content ratio Ba / (Ti+Zr) of Ba, Ti and Zr of 0.995 or more and 1.003 or less, the content of Mg relative to 100 molar parts of Ti is 0.5 molar parts or more and 5.0 molar parts or less than the content of Mg relative to 100 molar parts of Ti in the dielectric in the central region of the effective portion 11 in the width direction W and the length direction L, In the first end face side outer layer portion LG1 or the second end face side outer layer portion LG2, the dielectric in the region DL between the first end face LS1 or the second end face LS2 and the internal electrode layer 30 is The content ratio of Ba, Ti and Zr, Ba / (Ti+Zr), is 0.995 or more and 1.003 or less, By making the Mg content relative to 100 molar parts of Ti greater by 0.25 to 2.5 molar parts than the Mg content relative to 100 molar parts of Ti in the dielectric in the central region of the width direction W and length direction L of the effective portion 11, good results were obtained in the evaluation of moisture resistance reliability.

[0048] As shown in Table 2, when Mn was contained, good results in moisture resistance reliability were obtained in Examples 10 to 18. That is, in the length direction L of the first side surface outer layer portion WG1 or the second side surface outer layer portion WG2, In the central portion, the dielectric in a region DW between the first side surface WS1 or the second side surface WS2 and the internal electrode layer 30 has a content ratio of Ba, Ti and Zr, Ba / (Ti+Zr), of 0.995 or more and 1.003 or less, the content of Mn relative to 100 molar parts of Ti is 0.4 molar parts or more and 2.0 molar parts or less than the content of Mn relative to 100 molar parts of Ti in the dielectric in the central region of the effective portion 11 in the width direction W and the length direction L, In the first end face side outer layer portion LG1 or the second end face side outer layer portion LG2, the dielectric in the region DL between the first end face LS1 or the second end face LS2 and the internal electrode layer 30 is The content ratio of Ba, Ti and Zr, Ba / (Ti+Zr), is 0.995 or more and 1.003 or less, By making the Mn content relative to 100 molar parts of Ti greater by 0.2 molar parts or more and 1.0 molar parts or less than the Mn content relative to 100 molar parts of Ti in the dielectric in the central region of the width direction W and length direction L of the effective portion 11, good results were obtained in the evaluation of moisture resistance reliability.

[0049] The corner-side outer layer portions CG, which are adjacent to the first side surface-side outer layer portion WG1 or the second side surface-side outer layer portion WG2 in the length direction L and adjacent to the first end surface-side outer layer portion LG1 or the second end surface-side outer layer portion LG2 in the width direction W, are located at the four corners of the laminate 10 in a plan view. Because these regions are covered by the external electrodes 40 (FIGS. 3 and 4), they are susceptible to stress due to bending of the substrate, which can cause cracks or chips in the dielectric and damage the multilayer ceramic capacitor. However, by improving the density of the dielectric in the specified regions of the corner-side outer layer portions CG, the mechanical strength can be increased, thereby improving the reliability of the multilayer ceramic capacitor.

[0050] In the corner-side outer layer portion CG, a dielectric in a region DC surrounded by an imaginary surface extending in the width direction W from a tip end surface of the internal electrode layer 30 on the side opposite to the side connected to the external electrode 40, an imaginary surface extending in the length direction L from a side surface of the internal electrode layer 30 extending in the length direction L, the first side surface WS1 or the second side surface WS2, and the first end surface LS1 or the second end surface LS2 is The content ratio of Ba, Ti and Zr, Ba / (Ti+Zr), is 0.995 or more and 1.003 or less, When the content of Mg or Mn relative to 100 molar parts of Ti is 0.4 to 2.0 molar parts higher than the content of Mg or Mn relative to 100 molar parts of Ti in the dielectric in the central region of the effective portion 11 in the width direction W and length direction L, the porosity is 3% or less, and the grain growth can be such that the sintered particle diameter is 0.5 μm or less, thereby improving the density of the dielectric and increasing the mechanical strength, and effectively preventing damage such as cracking and chipping of the multilayer ceramic capacitor.

[0051] In the first side surface outer layer portion WG1 or the second side surface outer layer portion WG2, the dielectric in the region DW between the internal electrode layer 30 and the first side surface WS1 or between the internal electrode layer 30 and the second side surface WS2 preferably has an Mg or Mn content that increases from the internal electrode layer 30 toward the first side surface WS or from the internal electrode layer 30 toward the second side surface WS2. By increasing the Mg or Mn content, Mg and other elements are present at grain boundaries, suppressing grain growth, promoting densification, and reducing grain size. This makes it possible to achieve both moisture resistance reliability and reliability (suppressing the generation of large grains). Furthermore, because the firing temperatures differ between the side surface and the interior during sintering, increasing the Mg and other elements toward the first side surface WS or the second side surface WS2 can reduce densification and grain size variation.

[0052] In the internal electrode layer 30, in a range of 5 μm from the end in the width direction W to the center in the width direction W, as shown in Figure 7, it is preferable to form a structure in which the thickness of the internal electrode layer 30 in the stacking direction T gradually decreases toward the end to form an inclined surface, and the dielectric 20a in which all grain diameters are 500 nm or less is stacked on the inclined surface. In this way, by arranging a dense dielectric on the side surface of the internal electrode layer 30, it is possible to prevent moisture that has penetrated from the outside from reaching the internal electrode layer, and it is possible to provide high moisture resistance reliability. [Explanation of symbols]

[0053] 1. Multilayer ceramic capacitors 10 Laminate 11 Valid Part 20 dielectric layer 20a Dielectric 30 Internal electrode layer 31 First internal electrode layer 31A First opposing part 31B First drawer 32 Second internal electrode layer 32A Second opposing part 32B Second drawer 40 External electrode 40A First outer electrode 40B Second external electrode TS1 First principal surface TS2 Second principal surface WS1 First Aspect WS2 Second Aspect LS1 First end face LS2 Second end face TG main surface side outer layer TG1: First main surface outer layer TG2 Second main surface outer layer WG side outer layer WG1 First side outer layer WG2 Second outer layer on the side LG end side outer layer LG1 First outer layer on the end face side LG2 Second outer layer on the end face side CG Corner side outer layer DC, DL, DW area

Claims

1. A multilayer ceramic capacitor comprising: a laminate including a plurality of laminated dielectric layers and a plurality of internal electrode layers; and external electrodes arranged to be electrically connected to the internal electrode layers, the dielectric layer contains Ba, Ti, and Zr, and Mg or Mn; the laminate comprises a first main surface and a second main surface opposed to each other in a lamination direction of the dielectric layers and the internal electrode layers, a first side surface and a second side surface opposed to each other in a width direction which is a direction intersecting both the lamination direction and a length direction in which the internal electrode layers extend to the external electrodes, and a first end face and a second end face opposed to each other in a length direction which is a direction intersecting both the lamination direction and the width direction, the external electrodes are disposed on the first end surface and the second end surface, In the laminate, when a region where the internal electrode layers overlap each other as viewed from the stacking direction is defined as an effective portion, opposing regions sandwiching the effective portion in the stacking direction are defined as a first main surface side outer layer portion and a second main surface side outer layer portion, opposing regions sandwiching the effective portion in the width direction are defined as a first side surface side outer layer portion and a second side surface side outer layer portion, and opposing regions sandwiching the effective portion in the length direction are defined as a first end face side outer layer portion and a second end face side outer layer portion, In the center portion in the length direction of the first side surface side outer layer portion or the second side surface side outer layer portion, the dielectric in the region between the first side surface or the second side surface and the internal electrode layer is the content ratio of Ba, Ti and Zr, Ba / (Ti+Zr), is 0.995 or more and 1.003 or less; a content of Mg relative to 100 molar parts of Ti is larger by 0.5 molar parts or more and 5.0 molar parts or less than a content of Mg relative to 100 molar parts of Ti in a dielectric located in a central region of the effective portion in the width direction and the length direction, or a content of Mn relative to 100 molar parts of Ti is larger by 0.4 molar parts or more and 2.0 molar parts or less than a content of Mn relative to 100 molar parts of Ti in a dielectric located in a central region of the effective portion in the width direction and the length direction, In the first end face side outer layer portion or the second end face side outer layer portion, the dielectric in the region between the first end face or the second end face and the internal electrode layer is the content ratio of Ba, Ti and Zr, Ba / (Ti+Zr), is 0.995 or more and 1.003 or less; a multilayer ceramic capacitor in which a content of Mg relative to 100 molar parts of Ti is greater by 0.25 molar parts or more and 2.5 molar parts or less than a content of Mg relative to 100 molar parts of Ti in a dielectric located in a central region of the effective portion in the width direction and the length direction, or a content of Mn relative to 100 molar parts of Ti is greater by 0.2 molar parts or more and 1.0 molar part or less than a content of Mn relative to 100 molar parts of Ti in a dielectric located in a central region of the effective portion in the width direction and the length direction.

2. When a region adjacent to the first side surface side outer layer portion or the second side surface side outer layer portion in the length direction and adjacent to the first end surface side outer layer portion or the second end surface side outer layer portion in the width direction is defined as a corner surface side outer layer portion, In the corner-side outer layer portion, a dielectric in a region surrounded by an imaginary surface extending in the width direction from a tip end surface of the internal electrode layer on the side opposite to the side connected to the external electrode, an imaginary surface extending in the length direction from a side surface extending in the length direction of the internal electrode layer, the first side surface or the second side surface, and the first end surface or the second end surface, the content ratio of Ba, Ti and Zr, Ba / (Ti+Zr), is 0.995 or more and 1.003 or less; 2. The multilayer ceramic capacitor according to claim 1, wherein a content of Mg or Mn relative to 100 molar parts of Ti is greater by 0.4 molar parts or more and 2.0 molar parts or less than a content of Mg or Mn relative to 100 molar parts of Ti in a dielectric in a central region of said effective portion in said width direction and said length direction.

3. 3. The multilayer ceramic capacitor according to claim 1, wherein in the first side surface side outer layer portion or the second side surface side outer layer portion, the dielectric in the region between the internal electrode layer and the first side surface or between the internal electrode layer and the second side surface has an Mg or Mn content that increases in a direction from the internal electrode layer to the first side surface or from the internal electrode layer to the second side surface.

4. 3. The multilayer ceramic capacitor according to claim 1, wherein an inclined surface is formed in the internal electrode layer within a range of 5 μm from an end in the width direction toward a center in the width direction, in which the thickness of the internal electrode layer in the lamination direction gradually decreases toward the end, and the dielectric laminated on the inclined surface has grains all having particle diameters of 500 nm or less.

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