Multilayer ceramic capacitor

Abstract

A multilayer ceramic capacitor 1 is provided with: an element body 10 that comprises a plurality of dielectric ceramic layers 20 and a plurality of internal electrode layers 30 which are stacked in the thickness direction T; and external electrodes 11, 12 that are provided on a surface of the element body 10 and are electrically connected to the internal electrode layers 30. The dielectric ceramic layers 20 contain a perovskite oxide as a main component. The perovskite oxide contains at least one of barium (Ba), calcium (Ca), and strontium (Sr), at least one of titanium (Ti) and zirconium (Zr), and at least one of rare earth elements (Re). With respect to Re / (Ti + Zr) ratio of each pixel of an element mapping image in terms of atom% of the dielectric ceramic layer 20 obtained by scanning transmission electron microscopy-energy dispersive X-ray spectroscopy analysis (STEM-EDS analysis), if the range of 0 ≤ Re / (Ti + Zr) < 2 is divided by a section width of 0.002, the number of pixels belonging to each section is counted, and the frequency of the number of pixels is converted to a relative frequency so that the cumulative frequency of the range of 0 ≤ Re / (Ti + Zr) < 2 becomes 1, the concentration ratio variation of the Re / (Ti + Zr) ratio is defined by the following a1 to a4.　a1: The section to which the arithmetic mean of the Re / (Ti + Zr) ratios in the dielectric ceramic layer (hereinafter referred to as the concentration ratio arithmetic mean of Re / (Ti + Zr) ratios) belongs is defined as the mean concentration ratio belonging section of Re / (Ti + Zr) ratio.　a2: The relative frequency corresponding to a half of the relative frequency of the mean concentration ratio belonging section of Re / (Ti + Zr) ratio is defined as the half value of the Re / (Ti + Zr) ratio.　a3: The value obtained by multiplying the number of successive sections (excluding the section of 0 ≤ Re / (Ti + Zr) < 0.002) extending to the right and left with the mean concentration ratio belonging section of Re / (Ti + Zr) ratio as the point of origin among the sections in which the relative frequency is not less than the half value of the Re / (Ti + Zr) ratio by the section width of 0.002 is defined as the half-value width of the Re / (Ti + Zr) ratio.　a4: The value obtained by dividing the half-value width of the Re / (Ti + Zr) ratio by the concentration ratio arithmetic mean of Re / (Ti + Zr) ratios is defined as the concentration ratio variation of the Re / (Ti + Zr) ratio.　In addition, with respect to (Ba + Ca + Sr) / (Ti + Zr) ratio of each pixel of an element mapping image in terms of atom% of the dielectric ceramic layer obtained by STEM-EDS analysis, if the range of 0.3 ≤ (Ba + Ca + Sr) / (Ti + Zr) < 2.3 is divided by a section width of 0.02, the number of pixels belonging to each section is counted, and the frequency of the number of pixels is converted to a relative frequency so that the cumulative frequency of the range of 0.3 ≤ Re / (Ti + Zr) < 2.3 becomes 1, the concentration ratio variation of the (Ba + Ca + Sr) / (Ti + Zr) ratio is defined by the following b1 to b4.　b1: The section to which the arithmetic mean of the (Ba + Ca + Sr) / (Ti + Zr) ratios in the dielectric ceramic layer (hereinafter referred to as the concentration ratio arithmetic mean of (Ba + Ca + Sr) / (Ti + Zr) ratios) belongs is defined as the mean concentration ratio belonging section of (Ba + Ca + Sr) / (Ti + Zr) ratio.　b2: The relative frequency corresponding to a half of the relative frequency of the mean concentration ratio belonging section of (Ba + Ca + Sr) / (Ti + Zr) ratio is defined as the half value of the (Ba + Ca + Sr) / (Ti + Zr) ratio.　b3: The value obtained by multiplying the number of successive sections extending to the right and left with the mean concentration ratio belonging section of (Ba + Ca + Sr) / (Ti + Zr) ratio as the point of origin among the sections in which the relative frequency is not less than the half value of the (Ba + Ca + Sr) / (Ti + Zr) ratio

Description

Multilayer ceramic capacitor

[0001] This invention relates to a multilayer ceramic capacitor.

[0002] With advancements in electronic components and equipment, further miniaturization and increased capacitance of multilayer ceramic capacitors are expected. Furthermore, as the applications of multilayer ceramic capacitors expand, the demand for improved reliability is increasing. Therefore, there is a need for multilayer ceramic capacitors that offer high insulation properties, minimal degradation even at high temperatures, and superior reliability, while simultaneously allowing for thinner dielectric ceramic layers.

[0003] Patent Document 1 discloses a multilayer ceramic capacitor comprising a laminate having a plurality of stacked dielectric ceramic layers, and a plurality of external electrodes provided at mutually different positions on the end face of the laminate, wherein a plurality of internal electrodes are formed inside the laminate along a plurality of specific interfaces between the dielectric ceramic layers, with their respective edges exposed on the end face, so as to be electrically connected to one of the external electrodes, wherein the dielectric ceramic layers are made of a composite oxide containing metal elements such as Ba, Ca, Re (where Re is a rare earth element), Ti, Mg, and Mn.

[0004] Patent Document 2 describes a compound whose main component is (Ba,R)(Ti,V)O ３ System or (Ba, Ca, R)(Ti, V)O ３ Dielectric ceramics are disclosed, which are of a specific type (R is at least one selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y). Furthermore, Patent Document 2 discloses a multilayer ceramic capacitor comprising a capacitor body composed of a plurality of stacked dielectric ceramic layers and a plurality of internal electrodes formed along specific interfaces between the dielectric ceramic layers, and a plurality of external electrodes formed at different positions on the outer surface of the capacitor body and electrically connected to specific internal electrodes, wherein the dielectric ceramic layers are made of the dielectric ceramic.

[0005] Japanese Patent Publication No. 11-302072 Japanese Patent Publication No. 2011-195425

[0006] Patent documents 1 and 2 describe a technique for uniformly dissolving rare earth elements in particles constituting a dielectric ceramic layer. When a dielectric ceramic layer is thinned, if the uniformity of the concentration distribution of rare earth elements in the dielectric ceramic layer is insufficient, the resistance to degradation of the insulation resistance (IR) under high temperature and high voltage loads may decrease. However, as the demands for performance required of multilayer ceramic capacitors increase, there is still room for improvement in the techniques described in patent documents 1 and 2.

[0007] This invention was made to solve the above problems and aims to provide a multilayer ceramic capacitor that exhibits excellent electrical reliability and is less prone to deterioration of insulation resistance under high temperature and high voltage loads.

[0008] The multilayer ceramic capacitor of the present invention comprises a base body including a plurality of dielectric ceramic layers and a plurality of internal electrode layers stacked in the thickness direction, and an external electrode provided on the surface of the base body and electrically connected to the internal electrode layer. The dielectric ceramic layer mainly contains a perovskite-type oxide. The perovskite-type oxide includes at least one of barium (Ba), calcium (Ca), and strontium (Sr), at least one of titanium (Ti) and zirconium (Zr), and at least one of a rare earth element (Re). For the Re / (Ti+Zr) ratio of each pixel in the elemental mapping image obtained by STEM-EDS analysis (scanning transmission electron microscopy-energy dispersive X-ray spectroscopy) of the dielectric ceramic layer described above, the range 0 ≤ Re / (Ti+Zr) < 2 is divided into intervals of width 0.002, the number of pixels belonging to each interval is counted, and the frequency of the above number of pixels is converted to a relative frequency such that the cumulative frequency of 0 ≤ Re / (Ti+Zr) < 2 is 1. Then, the concentration ratio variation of the Re / (Ti+Zr) ratio is defined by a1 to a4 below. a1: The interval to which the arithmetic mean of the Re / (Ti+Zr) ratio in the dielectric ceramic layer (hereinafter referred to as the arithmetic mean of the concentration ratio of the Re / (Ti+Zr) ratio) belongs is defined as the average concentration ratio assignment interval of the Re / (Ti+Zr) ratio. a2: The relative frequency corresponding to half the relative frequency of the average concentration ratio assignment interval of the above Re / (Ti+Zr) ratio is defined as the half value of the Re / (Ti+Zr) ratio. a3: The value obtained by multiplying the number of continuous intervals that extend to the left and right from the average concentration ratio assignment interval of the above Re / (Ti+Zr) ratio (excluding intervals where 0 ≤ Re / (Ti+Zr) < 0.002) among the intervals that are greater than or equal to the half value of the above Re / (Ti+Zr) ratio by the interval width of 0.002 is defined as the half width of the Re / (Ti+Zr) ratio. a4: The value obtained by dividing the half width of the above Re / (Ti+Zr) ratio by the arithmetic mean of the concentration ratios of the above Re / (Ti+Zr) ratio is defined as the concentration ratio variability of the above Re / (Ti+Zr) ratio.Furthermore, regarding the (Ba+Ca+Sr) / (Ti+Zr) ratio of each pixel in the elemental mapping image converted to atom%, obtained by STEM-EDS analysis of the dielectric ceramic layer, the range 0.3 ≤ (Ba+Ca+Sr) / (Ti+Zr) < 2.3 is divided into intervals of 0.02 width, the number of pixels belonging to each interval is counted, and the frequency of the above number of pixels is converted to a relative frequency such that the cumulative frequency of 0.3 ≤ Re / (Ti+Zr) < 2.3 becomes 1. Then, the concentration ratio variation of the (Ba+Ca+Sr) / (Ti+Zr) ratio is defined by b1 to b4 below. b1: The interval to which the arithmetic mean of the (Ba+Ca+Sr) / (Ti+Zr) ratio in the dielectric ceramic layer (hereinafter referred to as the arithmetic mean of the concentration ratio of the (Ba+Ca+Sr) / (Ti+Zr) ratio) belongs is defined as the average concentration ratio assignment interval of the (Ba+Ca+Sr) / (Ti+Zr) ratio. b2: The relative frequency corresponding to half of the relative frequency of the average concentration ratio assignment interval of the (Ba+Ca+Sr) / (Ti+Zr) ratio is defined as the half value of the (Ba+Ca+Sr) / (Ti+Zr) ratio. b3: The value obtained by multiplying the number of continuous intervals extending to the left and right from the average concentration ratio assignment interval of the above (Ba+Ca+Sr) / (Ti+Zr) ratio, among the intervals that are greater than or equal to half of the above (Ba+Ca+Sr) / (Ti+Zr) ratio, by the interval width of 0.02 is defined as the half-width of the (Ba+Ca+Sr) / (Ti+Zr) ratio. b4: The value obtained by dividing the half-width of the above (Ba+Ca+Sr) / (Ti+Zr) ratio by the arithmetic mean of the concentration ratios of the above (Ba+Ca+Sr) / (Ti+Zr) ratio is defined as the concentration ratio variability of the above (Ba+Ca+Sr) / (Ti+Zr) ratio. The normalized concentration ratio variation of the Re / (Ti+Zr) ratio, obtained by dividing the concentration ratio variation of the Re / (Ti+Zr) ratio by the concentration ratio variation of the (Ba+Ca+Sr) / (Ti+Zr) ratio, is 3.50 or less.

[0009] According to the present invention, it is possible to provide a multilayer ceramic capacitor that is less prone to deterioration of insulation resistance under high temperature and high voltage loads and has excellent electrical reliability.

[0010] Figure 1 is a schematic perspective view showing an example of a multilayer ceramic capacitor of the present invention. Figure 2 is an example of an LT cross-sectional view of the multilayer ceramic capacitor shown in Figure 1, including the length direction L and thickness direction T along the line II-II. Figure 3 is an example of a WT cross-sectional view of the multilayer ceramic capacitor shown in Figure 1, including the width direction W and thickness direction T along the line III-III. Figure 4 is an example of a bright-field image of a dielectric ceramic layer taken with a scanning transmission electron microscope. Figure 5 is an example of an EDS mapping image showing the distribution of Dy elements in the dielectric ceramic layer shown in Figure 4. Figure 6 is an example of the relative frequency distribution of the Re / (Ti+Zr) ratio in the dielectric ceramic layer constituting a multilayer ceramic capacitor within the scope of the present invention. Figure 7 is an example of the relative frequency distribution of the (Ba+Ca+Sr) / (Ti+Zr) ratio in the dielectric ceramic layer constituting a multilayer ceramic capacitor within the scope of the present invention. Figure 8 is another example of the relative frequency distribution of the Re / (Ti+Zr) ratio in the dielectric ceramic layer constituting a multilayer ceramic capacitor within the scope of the present invention. Figure 9 shows another example of the relative frequency distribution of the (Ba+Ca+Sr) / (Ti+Zr) ratio in the dielectric ceramic layer constituting a multilayer ceramic capacitor that falls within the scope of the present invention. Figure 10 shows another example of the relative frequency distribution of the Re / (Ti+Zr) ratio in the dielectric ceramic layer constituting a multilayer ceramic capacitor that falls outside the scope of the present invention. Figure 11 shows another example of the relative frequency distribution of the (Ba+Ca+Sr) / (Ti+Zr) ratio in the dielectric ceramic layer constituting a multilayer ceramic capacitor that falls outside the scope of the present invention.

[0011] The multilayer ceramic capacitor of the present invention will be described below. However, the present invention is not limited to the following embodiments, and can be modified and applied as appropriate without altering the essence of the invention. Furthermore, a combination of two or more of the preferred configurations described in the following embodiments also constitutes the present invention.

[0012] In this specification, terms describing relationships between elements (e.g., "perpendicular," "parallel," "orthogonal," etc.) and terms describing the shapes of elements do not represent only strict meanings, but also include a range of substantially equivalent terms, such as differences of a few percent.

[0013] The following diagrams are schematic representations, and their dimensions, aspect ratios, and scales may differ from those of the actual product. The same reference numerals are used for identical or equivalent parts in the diagrams. Furthermore, identical elements are denoted by the same reference numerals in each diagram, and redundant explanations are omitted.

[0014] Figure 1 is a schematic perspective view showing an example of the multilayer ceramic capacitor of the present invention.

[0015] The multilayer ceramic capacitor 1 shown in Figure 1 comprises a base body 10 and external electrodes 11 and 12 provided on the surface of the base body 10. In the base body 10, the length direction, width direction, and thickness direction are defined by double arrows L, W, and T, respectively.

[0016] The base body 10 is, for example, a rectangular parallelepiped. In this case, the base body 10 has a first main surface 10a and a second main surface 10b that are opposite to the thickness direction T, a first side surface 10c and a second side surface 10d that are opposite to the width direction W which is perpendicular to the thickness direction T, and a first end surface 10e and a second end surface 10f that are opposite to the length direction L which is perpendicular to the thickness direction T and the width direction W.

[0017] At least one of the corners and edges of the base body 10 may be rounded. Here, the corners are the parts where the three faces of the base body 10 intersect, and the edges are the parts where the two faces of the base body 10 intersect.

[0018] The external electrode 11 is provided on the first end face 10e of the base body 10. The external electrode 11 may wrap around to a part of the first main surface 10a, the second main surface 10b, the first side surface 10c, and the second side surface 10d of the base body 10.

[0019] The external electrode 12 is provided on the second end face 10f of the base body 10. The external electrode 12 may wrap around to a part of the first main surface 10a, the second main surface 10b, the first side surface 10c, and the second side surface 10d of the base body 10.

[0020] The dimensions of the multilayer ceramic capacitor 1 are not particularly limited. For example, the length L is 0.2 mm or more and 5.7 mm or less, the width W is 0.1 mm or more and 5.0 mm or less, and the thickness T is 0.1 mm or more and 5.0 mm or less.

[0021] Figure 2 is an example of a cross-sectional view (LT) of the multilayer ceramic capacitor shown in Figure 1, including the length direction L and thickness direction T along the line II-II. Figure 3 is an example of a cross-sectional view (WT) of the multilayer ceramic capacitor shown in Figure 1, including the width direction W and thickness direction T along the line III-III.

[0022] The base body 10 includes a plurality of dielectric ceramic layers 20 and a plurality of internal electrode layers 30 stacked in the thickness direction T.

[0023] The internal electrode layer 30 includes a first internal electrode layer 31 and a second internal electrode layer 32 that are alternately arranged in the thickness direction T.

[0024] The first internal electrode layer 31 extends to the first end face 10e of the base body 10, where it is electrically connected to the external electrode 11.

[0025] The second internal electrode layer 32 extends to the second end face 10f of the base body 10, where it is electrically connected to the external electrode 12.

[0026] The first internal electrode layer 31 and the second internal electrode layer 32, which face each other with the dielectric ceramic layer 20 in between, are not electrically connected. Therefore, when a voltage is applied between the first internal electrode layer 31 and the second internal electrode layer 32 via the external electrodes 11 and 12, charge accumulates. The accumulated charge generates capacitance, thereby enabling the device to function as a capacitive element.

[0027] An outer layer portion 25, consisting only of dielectric ceramic layers 20, may be provided on the outside of the plurality of dielectric ceramic layers 20 and plurality of internal electrode layers 30 that are stacked in the thickness direction T. The outer layer portion 25 is located on both main surfaces of the base body 10 and is a dielectric ceramic layer located between each main surface and the internal electrode layer 30 closest to that main surface. On the other hand, the region sandwiched between both outer layer portions 25 can also be called the inner layer portion.

[0028] The dielectric ceramic layer 20 is composed of ceramic. Specifically, the dielectric ceramic layer 20 mainly contains perovskite-type oxide. Alternatively, it can be said that the dielectric ceramic layer 20 is composed of a sintered body of perovskite-type oxide.

[0029] In this specification, the main component means the component having the largest mass ratio in the ceramic. The mass ratio of the main component is not particularly limited as long as it is less than 100% by mass. For example, it may be 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more.

[0030] The perovskite-type oxide contained as the main component in the dielectric ceramic layer 20 contains at least one of barium (Ba), calcium (Ca), and strontium (Sr), at least one of titanium (Ti) and zirconium (Zr), and at least one of rare earth elements (Re).

[0031] The above perovskite-type oxide preferably contains at least Ba among Ba, Ca, and Sr, and more preferably further contains at least one of Ca and Sr.

[0032] The perovskite-type oxide contained as the main component in the dielectric ceramic layer 20 is, for example, a barium titanate (BaTiO ３ )-based compound. BaTiO ３ shows a tetragonal crystal structure at room temperature and is a ferroelectric body showing a high dielectric constant. Therefore, by using a BaTiO s ３ -based compound as the main component, the dielectric constant of the dielectric ceramic layer 20 can be increased, and it becomes possible to increase the capacitance of the capacitor.

[0033] For example, when the perovskite-type oxide is a BaTiO ３ -based compound, the BaTiO ３ -based compound may be a compound in which a part of Ba and / or Ti contained in BaTiO ３ is substituted with another element. For example, a part of Ba may be substituted with an alkaline earth metal element such as Ca or Sr, or a part of Ti may be substituted with a transition metal element such as Zr or hafnium (Hf). Further, BaTiO ３The molar ratio of A-site elements (Ba, Ca, Sr, etc.) to B-site elements (Ti, Zr, Hf, etc.) in a compound (hereinafter also referred to as the A / B ratio) is not strictly limited to 1:1. As long as the perovskite crystal structure is maintained, deviations in the molar ratio between A-site and B-site elements are acceptable.

[0034] Rare earth elements (Re) are a general term for the elements that make up the group in the periodic table consisting of scandium (Sc) with atomic number 21, yttrium (Y) with atomic number 39, and lanthanum (La) with atomic number 57 to lutetium (Lu) with atomic number 71. Perovskite oxides may contain one type of rare earth element (Re), or they may contain a combination of multiple types of rare earth elements (Re).

[0035] The inclusion of rare earth elements (Re) in the dielectric ceramic layer 20 improves the reliability and various properties of the multilayer ceramic capacitor 1, such as the temperature characteristics of the dielectric constant. ３ Perovskite-type oxides such as those in the iontochemistry system may contain many oxygen vacancies generated during the firing process. These oxygen vacancies tend to reduce insulation resistance when accompanied by electronic compensation, and they also tend to move under an electric field, leading to a decrease in insulation resistance over time. Therefore, if the dielectric ceramic layer 20 contains a rare earth element (Re), BaTiO ３ It tends to form solid solutions at the A site (e.g., Ba site) or B site (e.g., Ti site) of perovskite-type oxides such as system compounds. The solid-solution rare earth element (Re) acts as a donor or acceptor, hindering the movement of oxygen vacancies or suppressing the generation of conduction electrons. As a result, the degradation of insulation resistance is reduced and the high-temperature load life is improved. Also, BaTiO ３ Perovskite-type oxides such as those in the BaTiO2 system exhibit a large temperature dependence of their dielectric constant near the Curie temperature Tc. ３ By solid-solving rare earth elements (Re) in perovskite-type oxides such as system compounds, it becomes possible to flatten the temperature dependence of the dielectric constant over a wide range, including the Curie temperature Tc.

[0036] The type of rare earth element (Re) is not particularly limited, but it is preferable that the rare earth element (Re) includes at least one selected from the group consisting of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), and it is more preferable that it includes dysprosium (Dy). Dy is an element located near the middle of the lanthanide group in the periodic table, and its ionic radius is also of an intermediate size. Therefore, BaTiO ３ The material can be solid-solved in both the A site (e.g., the Ba site) and the B site (e.g., the Ti site) of perovskite-type oxides such as system compounds, which is effective in improving reliability. The dielectric ceramic layer 20 may contain only Dy as the rare earth element (Re), or it may contain other rare earth elements (Re) together with Dy.

[0037] Figure 4 is an example of a bright-field image obtained by scanning transmission electron microscopy of a dielectric ceramic layer. Figure 5 is an example of an EDS mapping image showing the distribution of the Dy element in the dielectric ceramic layer shown in Figure 4.

[0038] By performing STEM-EDS analysis (scanning transmission electron microscopy-energy dispersive X-ray spectroscopy) on the dielectric ceramic layer 20 in the field of view shown in Figure 4, it is possible to simultaneously obtain the distribution of multiple elements (elemental mapping image) as a separate image, in addition to Dy shown in Figure 5. In the embodiment described later, the elemental mapping image consists of 256 × 256 pixels. From the pixel information of the same coordinate, the Re / (Ti+Zr) ratio, such as the Dy / (Ti+Zr) ratio, can be calculated. Furthermore, from the pixel information of the same coordinate, the (Ba+Ca+Sr) / (Ti+Zr) ratio can be calculated.

[0039] Figure 6 shows an example of the relative frequency distribution of the Re / (Ti+Zr) ratio in the dielectric ceramic layer constituting a multilayer ceramic capacitor that falls within the scope of the present invention.

[0040] The Re / (Ti+Zr) ratio of each pixel in the elemental mapping image converted to atom percent, obtained by STEM-EDS analysis of the dielectric ceramic layer 20, can be obtained as shown in Figure 6. This is achieved by dividing the range 0 ≤ Re / (Ti+Zr) < 2 into intervals of 0.002, counting the number of pixels belonging to each interval, and converting the frequency of the above pixel counts into relative frequencies such that the cumulative frequency of 0 ≤ Re / (Ti+Zr) < 2 becomes 1. Note that in Figure 6, the range 0 ≤ Re / (Ti+Zr) < 0.15 is enlarged.

[0041] Figure 7 shows an example of the relative frequency distribution of the (Ba + Ca + Sr) / (Ti + Zr) ratio in the dielectric ceramic layer constituting a multilayer ceramic capacitor within the scope of the present invention.

[0042] The (Ba+Ca+Sr) / (Ti+Zr) ratio of each pixel in the elemental mapping image converted to atom percent, obtained by STEM-EDS analysis of the dielectric ceramic layer 20, can be divided into intervals of 0.02 in the range of 0.3 ≤ (Ba+Ca+Sr) / (Ti+Zr) < 2.3, as shown in Figure 7. The number of pixels belonging to each interval is counted, and the frequency of the above number of pixels is converted to a relative frequency distribution such that the cumulative frequency of 0.3 ≤ (Ba+Ca+Sr) / (Ti+Zr) < 2.3 is 1. Note that in Figure 7, the range of 0.5 ≤ (Ba+Ca+Sr) / (Ti+Zr) < 2.0 is enlarged.

[0043] The multilayer ceramic capacitor 1 is characterized in that the normalized concentration ratio variation of the Re / (Ti+Zr) ratio, obtained by dividing the concentration ratio variation of the Re / (Ti+Zr) ratio defined by a1 to a4 below by the concentration ratio variation of the (Ba+Ca+Sr) / (Ti+Zr) ratio defined by b1 to b4 below, is 3.50 or less.

[0044] The variation in the concentration ratio of the Re / (Ti+Zr) ratio is defined by a1 to a4 below, based on the relative frequency distribution of the Re / (Ti+Zr) ratio shown in Figure 6. a1: The interval to which the arithmetic mean of the Re / (Ti+Zr) ratio in the dielectric ceramic layer 20 belongs (hereinafter referred to as the arithmetic mean of the concentration ratio of the Re / (Ti+Zr) ratio) (the interval shown as a1 in Figure 6) is defined as the average concentration ratio assignment interval of the Re / (Ti+Zr) ratio. a2: The relative frequency corresponding to half the relative frequency of the average concentration ratio assignment interval of the Re / (Ti+Zr) ratio (the relative frequency shown as a2 in Figure 6) is defined as the half value of the Re / (Ti+Zr) ratio. a3: The width at half maximum of the Re / (Ti+Zr) ratio is defined as the value obtained by multiplying the number of continuous intervals extending to the left and right from the average concentration ratio assignment interval of the Re / (Ti+Zr) ratio (excluding intervals where 0 ≤ Re / (Ti+Zr) < 0.002) among the intervals where the Re / (Ti+Zr) ratio is greater than or equal to half maximum by the interval width of 0.002 (the width shown as a3 in Figure 6). a4: The value obtained by dividing the width at half maximum of the Re / (Ti+Zr) ratio by the arithmetic mean of the concentration ratios of the Re / (Ti+Zr) ratio is defined as the concentration ratio variability of the Re / (Ti+Zr) ratio.

[0045] On the other hand, the variation in the concentration ratio of the (Ba+Ca+Sr) / (Ti+Zr) ratio is defined by b1 to b4 below, based on the relative frequency distribution of the (Ba+Ca+Sr) / (Ti+Zr) ratio shown in Figure 7. b1: The interval to which the arithmetic mean of the (Ba+Ca+Sr) / (Ti+Zr) ratio in the dielectric ceramic layer 20 belongs (hereinafter referred to as the arithmetic mean of the concentration ratio of the (Ba+Ca+Sr) / (Ti+Zr) ratio) is assigned (the interval shown as b1 in Figure 7) is defined as the average concentration ratio assignment interval of the (Ba+Ca+Sr) / (Ti+Zr) ratio. b2: The relative frequency corresponding to half the relative frequency of the average concentration ratio assignment interval for the (Ba+Ca+Sr) / (Ti+Zr) ratio (shown as b2 in Figure 7) is defined as the half-value of the (Ba+Ca+Sr) / (Ti+Zr) ratio. b3: Among the intervals that are greater than or equal to half the value of the (Ba+Ca+Sr) / (Ti+Zr) ratio, the value obtained by multiplying the number of continuous intervals extending to the left and right from the average concentration ratio assignment interval for the (Ba+Ca+Sr) / (Ti+Zr) ratio by the interval width of 0.02 (shown as b3 in Figure 7) is defined as the half-width of the (Ba+Ca+Sr) / (Ti+Zr) ratio. b4: The value obtained by dividing the full width at half maximum of the (Ba+Ca+Sr) / (Ti+Zr) ratio by the arithmetic mean of the concentration ratios of the (Ba+Ca+Sr) / (Ti+Zr) ratio is defined as the concentration ratio variability of the (Ba+Ca+Sr) / (Ti+Zr) ratio.

[0046] In the multilayer ceramic capacitor 1, the variation in the normalized concentration ratio of the Re / (Ti+Zr) ratio is preferably 2.80 or less, and more preferably less than 2.30. On the other hand, the variation in the normalized concentration ratio of the Re / (Ti+Zr) ratio is, for example, 1.00 or more.

[0047] Figure 8 shows another example of the relative frequency distribution of the Re / (Ti+Zr) ratio in the dielectric ceramic layer constituting a multilayer ceramic capacitor within the scope of the present invention. Figure 9 shows another example of the relative frequency distribution of the (Ba+Ca+Sr) / (Ti+Zr) ratio in the dielectric ceramic layer constituting a multilayer ceramic capacitor within the scope of the present invention.

[0048] The normalized concentration ratio variation of the Re / (Ti+Zr) ratio, as determined from the examples shown in Figures 8 and 9, is less than 2.30.

[0049] Figure 10 shows an example of the relative frequency distribution of the Re / (Ti+Zr) ratio in the dielectric ceramic layer constituting a multilayer ceramic capacitor, which is outside the scope of the present invention. Figure 11 shows an example of the relative frequency distribution of the (Ba+Ca+Sr) / (Ti+Zr) ratio in the dielectric ceramic layer constituting a multilayer ceramic capacitor, which is outside the scope of the present invention. Note that in Figure 10, when determining the full width at half maximum of the Re / (Ti+Zr) ratio shown at a3, even if it is a continuous interval extending to the left and right from the average concentration ratio assignment interval of the Re / (Ti+Zr) ratio shown at a2, the interval where 0 ≤ Re / (Ti+Zr) < 0.002 (the interval shown as X in Figure 10) is excluded.

[0050] The normalized concentration ratio variation of the Re / (Ti+Zr) ratio, as determined from the examples shown in Figures 10 and 11, exceeds 3.50.

[0051] As shown in Figures 6 to 9, by keeping the normalized concentration ratio variation of the Re / (Ti+Zr) ratio below 3.50, the deterioration of insulation resistance under high temperature and high voltage loads can be suppressed.

[0052] The normalized concentration ratio variation of the Re / (Ti+Zr) ratio is an indicator that reflects the concentration distribution of rare earth elements (Re) in the dielectric ceramic layer. The smaller this value, the sharper the concentration distribution, meaning that the rare earth elements are uniformly dispersed at a microscopic level. Conversely, the larger this value, the more non-uniform the concentration distribution of rare earth elements can be considered. In other words, the rare earth elements are distributed over a wide range of Re / (Ti+Zr) intervals. A non-uniform concentration distribution of rare earth elements leads to an increase in the proportion of regions where rare earth elements are at low concentrations. Rare earth elements have the effect of improving the resistance to degradation of insulation resistance, but this effect cannot be expected in regions where rare earth elements are at low concentrations. Conversely, if the concentration distribution of rare earth elements is uniform, that is, if the normalized concentration ratio variation of the Re / (Ti+Zr) ratio is small, the region where rare earth elements are at low concentrations shrinks, and as a result, the resistance to degradation of insulation resistance improves.

[0053] The thickness of the dielectric ceramic layer 20 is not particularly limited and may be, for example, 5.0 μm or less, 4.0 μm or less, 3.5 μm or less, 2.5 μm or less, 1.0 μm or less, or 0.8 μm or less. On the other hand, the thickness of the dielectric ceramic layer 20 may be, for example, 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, 0.6 μm or more, or 0.7 μm or more. If the thickness of the dielectric ceramic layer 20 is within the above range, deterioration of the insulating properties can be prevented. Furthermore, if the thickness of the dielectric ceramic layer 20 is within the above range, the dielectric ceramic layer 20 can be made thinner, and the capacitance can be improved.

[0054] The number of dielectric ceramic layers 20 is, for example, 50 or more and 1000 or less.

[0055] The average particle size of the ceramic grains contained in the dielectric ceramic layer 20 is not particularly limited, but is preferably 100 nm or more and 400 nm or less, and more preferably 150 nm or more and 300 nm or less.

[0056] The internal electrode layer 30 contains a conductive metal. Examples of conductive metals include nickel (Ni), copper (Cu), silver (Ag), palladium (Pd), and alloys containing at least one of these metals. The internal electrode layer 30 may also contain other components besides the conductive metal. Examples of other components include ceramic components that act as co-materials. Examples of ceramic components include BaTiO contained in the dielectric ceramic layer 20. ３ Examples include compound systems.

[0057] The thickness of the internal electrode layer 30 is not particularly limited, and is, for example, 0.3 μm or more and 0.7 μm or less. When the thickness of the internal electrode layer 30 is within the above range, defects such as electrode breaks are suppressed. Furthermore, when the thickness of the internal electrode layer 30 is within the above range, the decrease in the proportion of the electrically functional dielectric ceramic layer 20 in the capacitor is suppressed, making it possible to suppress a decrease in capacitance.

[0058] The thickness of the dielectric ceramic layer 20 and the internal electrode layer 30 is determined by observing the WT cross-section of the exposed substrate 10 by polishing using a scanning electron microscope (SEM). The thickness is measured along a center line passing through the center of the WT cross-section along the thickness direction T, and along a total of five lines drawn at equal intervals on both sides of this center line. The average of these five measured values ​​is then used.

[0059] Furthermore, the average particle size of the ceramic grains contained in the dielectric ceramic layer 20 can be measured by analyzing cross-sectional images scanned with a SEM. For example, the average particle size of the ceramic grains can be measured using software that measures the average particle size in accordance with the JIS G 0551:2013 standard.

[0060] The configuration of the external electrodes 11 and 12 is not particularly limited. The external electrodes 11 and 12 may have a laminated structure consisting of a base layer, a first plating layer, and a second plating layer, starting from the end face side of the multilayer ceramic capacitor 1. The base layer contains a metal such as nickel (Ni) or copper (Cu). The base layer may also contain ceramic powder as a co-material in addition to the metal. The first plating layer is, for example, a nickel (Ni) plating layer. The second plating layer is, for example, a tin (Sn) plating layer. A conductive resin layer may be provided between the base layer and the first plating layer. The conductive resin layer is a layer containing conductive metal particles such as copper (Cu), silver (Ag), and nickel (Ni), and resin. The external electrodes 11 and 12 are not limited in their form as long as they are electrically connected to the internal electrode layer 30 and function as external input / output terminals.

[0061] The manufacturing method of the multilayer ceramic capacitor of the present invention is not limited, as long as the above-mentioned requirements are satisfied.

[0062] The present invention provides a method for manufacturing a multilayer ceramic capacitor, comprising the steps of: preparing a green sheet containing, for example, at least one of barium (Ba), calcium (Ca), and strontium (Sr), at least one of titanium (Ti) and zirconium (Zr), and at least one of a rare earth element (Re) (green sheet preparation step); applying a conductive paste to the surface of the green sheet to obtain a green sheet with an internal electrode pattern formed on it (electrode pattern formation step); stacking and pressing a plurality of green sheets to obtain a laminated block (lamination step); cutting the obtained laminated block to obtain a laminated chip (cutting step); subjecting the obtained laminated chip to a binder removal process and a firing process to obtain a base body (firing step); and forming external electrodes on the obtained base body (external electrode formation step). Details of each step are described below.

[0063] <Green Sheet Manufacturing Process> In the green sheet manufacturing process, a green sheet is manufactured containing at least one of barium (Ba), calcium (Ca), and strontium (Sr), at least one of titanium (Ti) and zirconium (Zr), and at least one of rare earth elements (Re). The green sheet is a precursor of the dielectric ceramic layer and contains the main component raw material and additive raw material of the dielectric ceramic layer. The method for manufacturing the green sheet is not particularly limited. For example, a dielectric raw material can be manufactured by mixing the additive raw material with the main component raw material, a binder and a solvent can be added and mixed to the obtained dielectric raw material to form a slurry, and a green sheet can be formed from the obtained slurry.

[0064] For example, BaTiO ３ A powder of the compound is used. BaTiO ３ The compound can be synthesized using known ceramic synthesis methods such as solid-phase reaction, hydrothermal synthesis, or alkoxide synthesis, using known ceramic raw materials such as oxides, carbonates, hydroxides, nitrates, organic acid salts, alkoxides, and / or chelate compounds.

[0065] BaTiO ３When synthesizing compound iontochemistry, for example, in addition to Ba, Ti, and Re raw materials, Ca, Sr, Zr, etc., as needed, are wet-mixed in a ball mill, dried, and then heated. At this time, in order to facilitate the solid solution of the element Re, the Re raw material may be pre-milled (also called fine powdering). Furthermore, in order to facilitate the solid solution of elements such as Re, Ca, Sr, and Zr, the wet-mixing and heating process may be repeated after heating.

[0066] As the Ba raw material, known ceramic raw materials such as Ba oxides, carbonates, acetates, hydroxides, and chlorides can be used.

[0067] As the Ti raw material, known ceramic raw materials such as Ti oxides, acetates, and chlorides can be used.

[0068] As the Re raw material, known ceramic raw materials such as Re oxides, carbonates, acetates, and hydroxides can be used.

[0069] As the Ca raw material, known ceramic raw materials such as Ca oxides and carbonates are used.

[0070] As the Sr raw material, known ceramic raw materials such as Sr oxides and carbonates are used.

[0071] As the Zr raw material, known ceramic raw materials such as Zr oxides, acetates, and chlorides can be used.

[0072] The additive raw materials may also include raw materials for other additive components such as Mn, Mg, Si, Al, and V. Furthermore, the main component is BaTiO ３ To adjust the composition of the compound system, barium carbonate (BaCO3) is used. ３ ) and titanium dioxide (TiO ２ Ba raw materials and Ti raw materials such as ) may be added to the additive raw materials.

[0073] Slurry formation can be carried out by known methods; for example, by mixing an organic binder and an organic solvent with the dielectric material. As the organic binder, known binders such as polyvinyl butyral-based binders can be used. As the organic solvent, known solvents such as toluene and ethanol can be used. Additives such as plasticizers may be added to the slurry as needed. Furthermore, the green sheet can be formed by known methods such as the doctor blade method or the lip method.

[0074] <Electrode Pattern Formation Process> In the electrode pattern formation process, a conductive paste is applied to the surface of a green sheet to obtain a green sheet with an internal electrode pattern formed on it. The internal electrode pattern becomes the internal electrode layer after firing. Conductive metals included in the conductive paste include, for example, conductive materials such as nickel (Ni), copper (Cu), silver (Ag), palladium (Pd), and alloys containing these. In addition, ceramic components that act as co-materials may be added to the conductive paste. As ceramic components, for example, the main component raw materials of dielectric ceramic layers may be used. The conductive paste can be applied by known methods such as screen printing or gravure printing.

[0075] <Lamination Process> In the lamination process, multiple green sheets are laminated and compressed to obtain a laminated block. Green sheets with internal electrode patterns are used as the green sheets, but some green sheets without internal electrode patterns may also be used. Lamination and compression can be carried out by known methods.

[0076] <Cutting Process> In the cutting process, the obtained laminated block is cut to obtain a laminated chip. The cutting should be performed in such a way that a chip of a predetermined size is obtained and at least a portion of the internal electrode pattern is exposed on the end face of the laminated chip.

[0077] <Firing Process> In the firing process, the obtained laminated chip is subjected to a binder removal process and a firing process to obtain a base material. The firing process causes the green sheet and the internal electrode pattern to co-sinter, forming the dielectric ceramic layer and the internal electrode layer, respectively. The conditions for the binder removal process should be determined according to the type of organic binder contained in the green sheet and the internal electrode pattern. The firing process should be performed at a temperature at which the laminated chip becomes sufficiently dense. The firing process is performed, for example, with the main component BaTiO ３ The process is carried out in an atmosphere that prevents the reduction of the compound and suppresses the oxidation of the conductive metal. Furthermore, additional heat treatment may be performed after firing at an appropriate temperature and atmosphere.

[0078] <External Electrode Formation Process> In the external electrode formation process, external electrodes are formed on the obtained base material. The external electrodes can be formed by known methods. For example, they can be formed by applying and baking a conductive paste containing a metal such as silver (Ag), copper (Cu), and / or nickel (Ni) onto the end face of the base material exposed after the internal electrode layer has been drawn out. Alternatively, they can be formed by applying a conductive paste to both end faces of the laminated chip before firing and then performing a firing process. Furthermore, the formed electrodes can be used as a base layer, and a plating film of nickel (Ni) or tin (Sn) can be formed on top of it. A multilayer ceramic capacitor is then manufactured.

[0079] This specification discloses the following:

[0080] <1> A substrate comprising a plurality of dielectric ceramic layers and a plurality of internal electrode layers stacked in the thickness direction, and an external electrode provided on the surface of the substrate and electrically connected to the internal electrode layer, wherein the dielectric ceramic layer mainly contains a perovskite-type oxide, and the perovskite-type oxide contains at least one of barium (Ba), calcium (Ca), and strontium (Sr), at least one of titanium (Ti) and zirconium (Zr), and at least one of rare earth elements (Re), and the Re / (Ti+Zr) ratio of each pixel of the elemental mapping image converted to atom%, obtained by STEM-EDS analysis (scanning transmission electron microscopy-energy dispersive X-ray spectroscopy) of the dielectric ceramic layer, The range 0 ≤ Re / (Ti+Zr) < 2 is divided into intervals with a width of 0.002, the number of pixels belonging to each interval is counted, and the frequency of the above number of pixels is converted to a relative frequency such that the cumulative frequency of 0 ≤ Re / (Ti+Zr) < 2 is 1. The variation in the concentration ratio of the Re / (Ti+Zr) ratio is defined by a1 to a4 below: a1: The interval to which the arithmetic mean of the Re / (Ti+Zr) ratio in the dielectric ceramic layer (hereinafter referred to as the arithmetic mean of the concentration ratio of the Re / (Ti+Zr) ratio) belongs is defined as the average concentration ratio assignment interval of the Re / (Ti+Zr) ratio. a2: The relative frequency corresponding to half the relative frequency of the average concentration ratio assignment interval of the Re / (Ti+Zr) ratio is defined as the half value of the Re / (Ti+Zr) ratio. a3: The width at half maximum of the Re / (Ti+Zr) ratio is defined as the number of continuous intervals extending to the left and right from the average concentration ratio assignment interval of the Re / (Ti+Zr) ratio (excluding intervals where 0 ≤ Re / (Ti+Zr) < 0.002) among the intervals where the Re / (Ti+Zr) ratio is greater than or equal to half maximum, multiplied by the interval width of 0.002. a4: The value obtained by dividing the width at half maximum of the Re / (Ti+Zr) ratio by the arithmetic mean of the concentration ratios of the Re / (Ti+Zr) ratio is defined as the concentration ratio variation of the Re / (Ti+Zr) ratio. Furthermore, regarding the (Ba+Ca+Sr) / (Ti+Zr) ratio of each pixel in the elemental mapping image converted to atom%, obtained by STEM-EDS analysis of the dielectric ceramic layer,The range 0.3 ≤ (Ba + Ca + Sr) / (Ti + Zr) < 2.3 is divided into intervals with a width of 0.02, the number of pixels belonging to each interval is counted, and the frequency of the above number of pixels is converted to a relative frequency such that the cumulative frequency of 0.3 ≤ Re / (Ti + Zr) < 2.3 is 1. Then, the variation in the concentration ratio of (Ba + Ca + Sr) / (Ti + Zr) is defined by b1 to b4 below, b1: The interval to which the arithmetic mean of the (Ba + Ca + Sr) / (Ti + Zr) ratio in the dielectric ceramic layer (hereinafter referred to as the arithmetic mean of the concentration ratio of (Ba + Ca + Sr) / (Ti + Zr) ratio) belongs is defined as the average concentration ratio assignment interval of the (Ba + Ca + Sr) / (Ti + Zr) ratio. b2: The relative frequency corresponding to half the relative frequency of the average concentration ratio assignment interval of the above (Ba+Ca+Sr) / (Ti+Zr) ratio is defined as the half value of the (Ba+Ca+Sr) / (Ti+Zr) ratio. b3: Among the intervals that are greater than or equal to the half value of the above (Ba+Ca+Sr) / (Ti+Zr) ratio, the value obtained by multiplying the number of continuous intervals extending to the left and right from the average concentration ratio assignment interval of the above (Ba+Ca+Sr) / (Ti+Zr) ratio by the interval width of 0.02 is defined as the half width of the (Ba+Ca+Sr) / (Ti+Zr) ratio. b4: The variation in the concentration ratio of the (Ba+Ca+Sr) / (Ti+Zr) ratio is defined as the value obtained by dividing the full width at half maximum of the (Ba+Ca+Sr) / (Ti+Zr) ratio by the arithmetic mean of the concentration ratios of the (Ba+Ca+Sr) / (Ti+Zr) ratio. The normalized variation in the concentration ratio of the Re / (Ti+Zr) ratio, obtained by dividing the variation in the concentration ratio of the (Ba+Ca+Sr) / (Ti+Zr) ratio, is 3.50 or less, and this is a multilayer ceramic capacitor.

[0081] <2> The multilayer ceramic capacitor described in <1>, wherein the normalized concentration ratio variation of the above Re / (Ti+Zr) ratio is 2.80 or less.

[0082] <3> The multilayer ceramic capacitor described in <1> or <2>, wherein the normalized concentration ratio variation of the Re / (Ti+Zr) ratio is less than 2.30.

[0083] <4> The multilayer ceramic capacitor described in any one of <1> to <3>, wherein the above rare earth element (Re) contains dysprosium (Dy).

[0084] <5> The perovskite-type oxide is a multilayer ceramic capacitor according to any one of <1> to <4>, wherein the perovskite-type oxide contains at least Ba among Ba, Ca, and Sr.

[0085] <6> The multilayer ceramic capacitor according to <5>, wherein the perovskite oxide further comprises at least one of Ca and Sr.

[0086] <7> A multilayer ceramic capacitor according to any one of <1> to <6>, wherein the thickness of the dielectric ceramic layer is 3.5 μm or less.

[0087] <8> A multilayer ceramic capacitor according to any one of <1> to <7>, wherein the thickness of the dielectric ceramic layer is 2.5 μm or less.

[0088] <9> A multilayer ceramic capacitor according to any one of <1> to <8>, wherein the thickness of the dielectric ceramic layer is 1.0 μm or less.

[0089] <10> A multilayer ceramic capacitor according to any one of <1> to <9>, wherein the thickness of the dielectric ceramic layer is 0.8 μm or less.

[0090] The following are examples that more specifically disclose the multilayer ceramic capacitor of the present invention. However, the present invention is not limited to these examples.

[0091] [Example 1] <Fabrication of multilayer ceramic capacitors> BaCO ３ Powder, TiO ２ powder, and Dy ２ O ３ A powder was prepared. Composition formula: (Ba ０．９７５ Dy ０．０２５ ) (Ti ０．９７５ Dy ０．０２５ ) O ３ First, D ２ O ３ Weigh only the powder, ZrO ２ A 24-hour wet ball mill is performed using balls, and Dy ２ O ３The powder was thoroughly ground into a fine powder. In this slurry, the following mixtures were added in the proportions shown in the above compositional formula: BaCO3 ３ Powder and TiO ２ The powder was added, and a wet ball mill was performed for another 24 hours (note that the composition formula is for determining the weighing value and is not necessarily the same as the composition formula of sintered porcelain). The prepared slurry was dried, and the powder was heated in air at a rate of 600°C / hour to 1300°C, held for 2 hours, and then cooled to obtain calcined powder. This calcined powder was then mixed with ZrO again. ２ A wet ball mill was performed using balls for 24 hours to obtain a dry powder, and then the same synthesis at 1300°C as before was carried out. The heat treatment at 1300°C and the subsequent wet ball milling were repeated a total of three times to obtain the final calcined powder.

[0092] TiO in calcined powder ２ : BaCO3 per 100 moles ３ Powder: 1.0 mol part, MgCO ３ Powder: 1.0 mol part, MnCO ３ Powder: 0.3 moles, and SiO ２ Sol: 1.5 moles were added to the calcined powder, and the mixture was wet-mixed and dried to obtain dielectric powder.

[0093] A polyvinyl butyral-based binder and a plasticizer are added to the obtained dielectric powder, and then toluene and ethyl alcohol are added, resulting in ZrO ２ The material was slurryed using a wet ball mill with balls, and this slurry was molded to obtain a green sheet. The thickness of the green sheet was adjusted to 1.7 μm after sintering and densification.

[0094] A conductive paste, primarily composed of nickel, was screen-printed onto the surface of the obtained green sheet to form a pattern of conductive paste layers that would serve as the internal electrode layers.

[0095] Subsequently, 201 green sheets, each with a conductive paste layer formed on its surface, were stacked so that the sides with the conductive paste layer extended were staggered. Then, layers of green sheets without a conductive paste layer were placed above and below them, and the entire assembly was pressed together to create a laminated block.

[0096] The resulting multilayer blocks were cut into green multilayer chips. The cutting was done so that the length × width of the manufactured multilayer ceramic capacitors would be 3.2 mm × 1.6 mm.

[0097] The obtained green multilayer chips are N ２ The binder was removed by heat treatment at 280°C in an airflow. Subsequently, N ２ -H ２ -H ２ O-flow at 1260°C, oxygen partial pressure 1.6 × 10⁻⁶ －９ The firing process was carried out for two hours under MPa conditions.

[0098] In the fired laminated chip, a conductive paste mainly composed of Cu was applied to the end face portion where the internal electrode layer was drawn out, and the external electrode was formed by baking at 800°C. Furthermore, a Ni plating layer and an Sn plating layer were formed on the surface of the external electrode.

[0099] In this manner, a multilayer ceramic capacitor was fabricated. The resulting multilayer ceramic capacitor had external dimensions of 3.2 mm in length, 1.6 mm in width, and 1.6 mm in thickness. The number of dielectric ceramic layers sandwiched between the internal electrode layers was 200, and the thickness of each dielectric ceramic layer was 1.7 μm.

[0100] <IR Life Test> Highly accelerated life testing (HALT) was performed on the fabricated multilayer ceramic capacitors to determine the mean time to failure (MTTF). In the HALT test, a load of 160°C and 70V was applied to the samples. For each sample, the time at which the insulation resistance (IR) fell below 200kΩ was defined as the failure time. The failure times were measured for 72 samples fabricated under the same conditions.

[0101] Next, the obtained data was plotted on Weibull probability paper to obtain a Weibull distribution. The relationship between failure time and cumulative failure rate was linearly regressed on the obtained Weibull distribution, and its slope was determined as the shape parameter m. The failure time at which the cumulative failure rate reached 63.2% was also read, and the mean time to failure (MTTF) was determined using this failure time and the shape parameter m corresponding to the slope of the regression line. Samples with an MTF of 25 hours or more were judged as acceptable.

[0102] <STEM-EDS Analysis> The dielectric ceramic layer located at approximately half the length, width, and height of the multilayer ceramic capacitor was observed using a scanning transmission electron microscope (STEM), and component analysis of the fine region was performed using the attached energy-dispersive X-ray spectroscopy (EDS) system. The observation sample was prepared by thinning the dielectric ceramic layer using the focused ion beam (FIB) lift-out method. Observation and analysis were performed under the following conditions: - Instrument: JEOL Ltd., JEM-2200FS / Noran System 7 - Field of view: n=1 - Magnification: 60,000x - Pixel size: 9.2 nm / 1 pixel - Number of image pixels: 256 × 256 - Spot diameter: 1 nmφ - Measurement: 100 EDS cumulative measurements - EDS analysis software: Thermo Fisher Scientific K.K., NSS

[0103] The elemental mapping data obtained by EDS was processed using EDS analysis software as follows. First, quantitative analysis was performed on Ba, Ca, Sr, Ti, Zr, Ni, and rare earth elements so that their total was 100 atom%. For the quantification, the characteristic X-ray used was the K-line for Ca, Ti, and Ni, and the L-line for the other elements.

[0104] Since the STEM-EDS analysis field of view includes not only the dielectric ceramic layer but also the internal electrode layer, the region where the sum of the mol% of Ti and Zr is 10 atom% or more was defined as the dielectric ceramic layer.

[0105] Calculation of concentration ratio variation of Re / (Ti+Zr) ratio: For the dielectric ceramic layer defined earlier in the EDS elemental mapping image, the Re / (Ti+Zr) ratio, converted to atom percent, was determined using the quantitative values ​​of each pixel with the same coordinates in the mapping images of rare earth elements (Re), Ti, and Zr.

[0106] For the Re / (Ti+Zr) ratio obtained in this way, data within the range 0 ≤ Re / (Ti+Zr) < 2 was extracted. Next, the range was divided into equal intervals of 0.002, such as 0 ≤ Re / (Ti+Zr) < 0.002 as the first interval, 0.002 ≤ Re / (Ti+Zr) < 0.004 as the second interval, and so on, up to 1.998 ≤ Re / (Ti+Zr) < 2. The interval in which each extracted data point was placed was then determined, and the number of data points (number of pixels) for each interval was calculated.

[0107] Furthermore, the relative frequency for each interval was obtained by dividing by the total number of data points (number of pixels) included in the range 0 ≤ Re / (Ti + Zr) < 2, and the cumulative frequency accumulated over 0 ≤ Re / (Ti + Zr) < 2 was set to 1.

[0108] Here, a histogram was drawn with the vertical axis representing relative frequency and the horizontal axis representing the Re / (Ti+Zr) ratio. This histogram consists of vertical bars with a width of 0.002, representing the Re / (Ti+Zr) ratio.

[0109] Next, the arithmetic mean of the Re / (Ti+Zr) ratio was calculated for all pixels corresponding to the dielectric ceramic layer, and this was defined as the concentration ratio arithmetic mean of the Re / (Ti+Zr) ratio.

[0110] We determined the interval in the relative frequency distribution of the Re / (Ti+Zr) ratio to which the arithmetic mean of the concentration ratio of the Re / (Ti+Zr) ratio belongs (i.e., the average concentration ratio assignment interval of the Re / (Ti+Zr) ratio), and then found the height of half the bar height in the histogram of this interval (i.e., the half value of the Re / (Ti+Zr) ratio).

[0111] Next, regarding the relative frequency distribution of the Re / (Ti+Zr) ratio, the number of bars in the histogram whose bar height is greater than or equal to half of the Re / (Ti+Zr) ratio was counted, and this was multiplied by the interval width of 0.002 to find the full width at half maximum (FWHM) of the Re / (Ti+Zr) ratio. When calculating the FWHM, only continuous intervals extending to the left and right from the mean concentration ratio assignment interval were considered. However, intervals where 0 ≤ Re / (Ti+Zr) < 0.002 were excluded.

[0112] Next, the half-width of the Re / (Ti+Zr) ratio was divided by the arithmetic mean of the concentration ratios of the Re / (Ti+Zr) ratio to calculate the concentration ratio variability of the Re / (Ti+Zr) ratio.

[0113] Calculation of concentration ratio variation of (Ba+Ca+Sr) / (Ti+Zr) ratio For the dielectric ceramic layer defined earlier in the EDS elemental mapping image, the (Ba+Ca+Sr) / (Ti+Zr) ratio converted to atom percent was determined using the quantitative values ​​of each pixel with the same coordinates in the Ba, Ca, Sr, Ti, and Zr mapping images.

[0114] For the (Ba+Ca+Sr) / (Ti+Zr) ratio obtained in this way, data that falls within the range of 0.3 ≤ (Ba+Ca+Sr) / (Ti+Zr) < 2.3 was extracted. Next, the data was divided into two equal intervals of 0.02, starting with 0.3 ≤ (Ba+Ca+Sr) / (Ti+Zr) < 0.32 as the first interval, 0.32 ≤ (Ba+Ca+Sr) / (Ti+Zr) < 0.34 as the second interval, and so on, up to 2.28 ≤ (Ba+Ca+Sr) / (Ti+Zr) < 2.3. The interval in which each extracted data falls was then determined, and the number of data points (number of pixels) for each interval was calculated.

[0115] Furthermore, the relative frequency for each interval was obtained by dividing by the total number of data points (number of pixels) included in the range 0.3 ≤ (Ba + Ca + Sr) / (Ti + Zr) < 2.3, and the cumulative frequency calculated by accumulating over 0.3 ≤ (Ba + Ca + Sr) / (Ti + Zr) < 2.3 was set to 1.

[0116] Here, a histogram was drawn with the vertical axis representing relative frequency and the horizontal axis representing the (Ba+Ca+Sr) / (Ti+Zr) ratio. This histogram consists of vertical bars with a width of 0.02, representing the (Ba+Ca+Sr) / (Ti+Zr) ratio.

[0117] Next, the arithmetic mean of the (Ba+Ca+Sr) / (Ti+Zr) ratio was calculated for all pixels corresponding to the dielectric ceramic layer, and this was defined as the concentration ratio arithmetic mean of the (Ba+Ca+Sr) / (Ti+Zr) ratio.

[0118] We determined the interval in the relative frequency distribution of the (Ba+Ca+Sr) / (Ti+Zr) ratio to which the arithmetic mean of the concentration ratio of the (Ba+Ca+Sr) / (Ti+Zr) ratio belongs (i.e., the average concentration ratio assignment interval for the (Ba+Ca+Sr) / (Ti+Zr) ratio), and then found the height of half the bar height in the histogram of this interval (i.e., the half-value of the (Ba+Ca+Sr) / (Ti+Zr) ratio).

[0119] Next, for the relative frequency distribution of the (Ba+Ca+Sr) / (Ti+Zr) ratio, the number of bars whose histogram bar height is greater than or equal to half of the (Ba+Ca+Sr) / (Ti+Zr) ratio was counted, and this was multiplied by an interval width of 0.02 to find the full width at half maximum (FWHM) of the (Ba+Ca+Sr) / (Ti+Zr) ratio. When calculating the FWHM, only continuous intervals extending to the left and right from the mean concentration ratio assignment interval were considered.

[0120] Next, the half-width of the (Ba+Ca+Sr) / (Ti+Zr) ratio was divided by the arithmetic mean of the concentration ratios of the (Ba+Ca+Sr) / (Ti+Zr) ratio to calculate the concentration ratio variability of the (Ba+Ca+Sr) / (Ti+Zr) ratio.

[0121] Calculation of the normalized concentration ratio variation of the Re / (Ti+Zr) ratio The normalized concentration ratio variation of the Re / (Ti+Zr) ratio was obtained by dividing the concentration ratio variation of the Re / (Ti+Zr) ratio calculated above by the concentration ratio variation of the (Ba+Ca+Sr) / (Ti+Zr) ratio.

[0122] [Examples 2 to 7, Comparative Example 1] The only differences from Example 1 are the composition formula of the calcined powder and the method of its preparation. The composition formula of the calcined powder is as shown in Table 1. CaCO3 was used as the Ca raw material. ３ As a powder, Zr raw material is ZrO ２ Powder was used.

[0123] In Comparative Example 1, unlike Example 1, Dy ２ O ３ Without further pulverizing the powder, BaCO3 is prepared to achieve the predetermined ratio. ３ Powder, TiO ２ powder, and Dy ２ O ３ Weigh the powder and ZrO ２ A 12-hour wet ball milling process was performed using balls.

[0124] [Comparative Example 2] In Comparative Example 2, calcined powder is not synthesized. Instead of calcined powder, BaTiO is used as the main component. ３ Using powder, dielectric powder was prepared as follows. Otherwise, it is the same as in Example 1.

[0125] BaTiO with an average particle size of 200 nm ３ I prepared the powder. BaTiO ３ TiO ２ : BaCO3 per 100 moles ３ Powder: 1.0 mol part, Dy ２ O ３ Powder: 2.5 moles, MgCO ３ Powder: 1.0 mol part, MnCO ３ Powder: 0.3 moles, and SiO ２ Sol: 1.5 molar parts of BaTiO ３ The dielectric powder was obtained by adding it to the powder, wet mixing, and drying.

[0126]

[0127] Table 1 shows that in a multilayer ceramic capacitor with L x W dimensions of 3.2 mm x 1.6 mm, a dielectric ceramic layer thickness of 1.7 μm, and 200 effective elements, when subjected to a load of 70 V at 160 °C, the MTTF (mean time to failure) is 25 hours or more if the normalized concentration ratio variation of the Re / (Ti + Zr) ratio is kept below 3.50.

[0128] Furthermore, when the same temperature and voltage load is applied, the MTTF will be 40 hours or more if the normalized concentration ratio variation of the Re / (Ti+Zr) ratio is kept below 2.80.

[0129] Furthermore, by keeping the normalized concentration ratio variation of the Re / (Ti+Zr) ratio below 2.30 when the same temperature and voltage load is applied, the MTTF will be 55 hours or more.

[0130] In this example, a sample was considered acceptable if the normalized concentration ratio variation of the Re / (Ti+Zr) ratio was 3.50 or less. Note that this threshold of 3.50 may vary depending on the selection of the quantitative element, the setting of the Ti concentration when identifying the dielectric ceramic layer, and the way the interval width of Re / (Ti+Zr) is defined. It is also affected by the thickness of the thin section sample being observed and the observation magnification.

[0131] [Example 8] CaCO ３ Replace the powder with SrCO ３ Even when a multilayer ceramic capacitor is manufactured using the same method as in Example 4, except that powder is used, the normalized concentration ratio variation of the Re / (Ti+Zr) ratio will be less than 2.30, and the MTF may be 55 hours or more.

[0132] In the composition formula of the calcined powder in Example 8, the Sr content can be in the range of 0.005 to 0.10, for example (Ba ０．９４５ Sr ０．０３ Dy ０．０２５ ) (Ti ０．９７５ Dy ０．０２５ ) O ３ That is the case.

[0133] [Examples 9 to 13] Except for changing the composition formula of the calcined powder by using oxide powder containing rare earth elements other than Dy as raw materials, even when a multilayer ceramic capacitor is manufactured in the same manner as in Example 1, the normalized concentration ratio variation of the Re / (Ti+Zr) ratio is less than 2.30, and the MTF can be 55 hours or more.

[0134] In the composition formula of the calcined powder in Example 9, the total content of Gd can be in the range of 0.01 to 0.08, but for example (Ba ０．９７ Gd ０．０３ ) (Ti ０．９８ Gd ０．０２ ) O ３ That is the case.

[0135] In the composition formula of the calcined powder in Example 10, the total Ho content can be in the range of 0.01 to 0.08, but for example (Ba ０．９７５ Ho ０．０２５ ) (Ti ０．９７５ Ho ０．０２５ ) O３ It is.

[0136] In the composition formula of the calcined powder in Example 11, the total content of Er can be in the range of 0.01 to 0.08. For example, (Ba ０．９８５ Er ０．０１５ )(Ti ０．９８５ Er ０．０１５ )O ３ It is.

[0137] In the composition formula of the calcined powder in Example 12, the total content of Y can be in the range of 0.01 to 0.08. For example, (Ba ０．９８５ Y ０．０１５ )(Ti ０．９８５ Y ０．０１５ )O ３ It is.

[0138] In the composition formula of the calcined powder in Example 13, the total content of a plurality of rare earth elements can be in the range of 0.01 to 0.08. For example, (Ba ０．９８５ Dy ０．０１５ )(Ti ０．９８５ Tb ０．０１５ )O ３ It is.

[0139] [Examples 14 to 17] When manufacturing a multilayer ceramic capacitor by the same method as in Example 2, except that the composition formula of the calcined powder is changed by using an oxide powder containing the rare earth element as a raw material for rare earth elements other than Dy, the normalized concentration ratio variation of the Re / (Ti + Zr) ratio is 2.80 or less, and the MTTF can be 40 hours or more.

[0140] The composition formula of the calcined powder in Example 14 is, for example, (Ba ０．９８５ Dy ０．０１４６ La ０．０００２ Nd ０．０００２ )(Ti ０．９８５ Dy ０．０１５ )O ３ It is.

[0141] The composition formula of the calcined powder in Example 15 is, for example, (Ba ０．９８５ Dy ０．０１５ )(Ti ０．９８５ Dy ０．０１４６ Yb ０．０００２ Lu ０．０００２ )O３ That is the case.

[0142] The compositional formula of the calcined powder in Example 16 is, for example, (Ba ０．９８５ Dy ０．０１４６ Eu ０．０００２ Sm ０．０００２ ) (Ti ０．９８５ Dy ０．０１５ ) O ３ That is the case.

[0143] The compositional formula of the calcined powder in Example 17 is, for example, (Ba ０．９８５ Dy ０．０１４６ Ce ０．０００２ Pr ０．０００２ ) (Ti ０．９８５ Dy ０．０１４８ Tm ０．０００２ ) O ３ That is the case.

[0144] In addition, as shown in Examples 14 to 17, rare earth elements added in small amounts may not be accurately detected by STEM-EDS. For example, La may not be able to be separated because its characteristic X-ray energy overlaps with that of the main component Ba. Therefore, in Examples 14 to 17, it is preferable to use only Dy for Re when determining the Re / (Ti+Zr) ratio. The presence of rare earth elements in the sintered body that could not be accurately detected by STEM-EDS can be separately confirmed by inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0145] 1 Multilayer ceramic capacitor 10 Base body 10a First main surface 10b Second main surface 10c First side surface 10d Second side surface 10e First end surface 10f Second end surface 11, 12 External electrodes 20 Dielectric ceramic layer 25 Outer layer 30 Internal electrode layer 31 First internal electrode layer 32 Second internal electrode layer L Length direction T Thickness direction W Width direction

Claims

1. A substrate comprising a plurality of dielectric ceramic layers and a plurality of internal electrode layers stacked in the thickness direction, and an external electrode provided on the surface of the substrate and electrically connected to the internal electrode layer, wherein the dielectric ceramic layer mainly contains a perovskite-type oxide, and the perovskite-type oxide contains at least one of barium (Ba), calcium (Ca), and strontium (Sr), at least one of titanium (Ti) and zirconium (Zr), and at least one of a rare earth element (Re), and the Re / (Ti+Zr) ratio of each pixel of the elemental mapping image converted to atom%, obtained by STEM-EDS analysis (scanning transmission electron microscopy-energy dispersive X-ray spectroscopy) of the dielectric ceramic layer, The range 0 ≤ Re / (Ti+Zr) < 2 is divided into intervals with a width of 0.002, the number of pixels belonging to each interval is counted, and the frequency of the number of pixels is converted to a relative frequency such that the cumulative frequency of 0 ≤ Re / (Ti+Zr) < 2 is 1. The variation in the concentration ratio of the Re / (Ti+Zr) ratio is defined by a1 to a4 below: a1: The interval to which the arithmetic mean of the Re / (Ti+Zr) ratio in the dielectric ceramic layer (hereinafter referred to as the arithmetic mean of the concentration ratio of the Re / (Ti+Zr) ratio) belongs is defined as the average concentration ratio assignment interval of the Re / (Ti+Zr) ratio. a2: The relative frequency corresponding to half the relative frequency of the average concentration ratio assignment interval of the Re / (Ti+Zr) ratio is defined as the half value of the Re / (Ti+Zr) ratio. a3: The width at half maximum of the Re / (Ti+Zr) ratio is defined as the number of continuous intervals extending to the left and right from the average concentration ratio assignment interval of the Re / (Ti+Zr) ratio (excluding intervals where 0 ≤ Re / (Ti+Zr) < 0.002) among the intervals where the Re / (Ti+Zr) ratio is greater than or equal to half maximum, multiplied by the interval width of 0.

002. a4: The value obtained by dividing the width at half maximum of the Re / (Ti+Zr) ratio by the arithmetic mean of the concentration ratios of the Re / (Ti+Zr) ratio is defined as the concentration ratio variation of the Re / (Ti+Zr) ratio. Furthermore, regarding the (Ba+Ca+Sr) / (Ti+Zr) ratio of each pixel in the elemental mapping image converted to atom%, obtained by STEM-EDS analysis of the dielectric ceramic layer,The range 0.3 ≤ (Ba + Ca + Sr) / (Ti + Zr) < 2.3 is divided into intervals with a width of 0.02, the number of pixels belonging to each interval is counted, and the frequency of the number of pixels is converted to a relative frequency such that the cumulative frequency of 0.3 ≤ Re / (Ti + Zr) < 2.3 is 1. The variation in the concentration ratio of the (Ba + Ca + Sr) / (Ti + Zr) ratio is defined by b1 to b4 below, b1: The interval to which the arithmetic mean of the (Ba + Ca + Sr) / (Ti + Zr) ratio in the dielectric ceramic layer belongs (hereinafter referred to as the arithmetic mean of the concentration ratio of the (Ba + Ca + Sr) / (Ti + Zr) ratio) is defined as the average concentration ratio assignment interval of the (Ba + Ca + Sr) / (Ti + Zr) ratio. b2: The relative frequency corresponding to half the relative frequency of the average concentration ratio assignment interval of the (Ba+Ca+Sr) / (Ti+Zr) ratio is defined as the half value of the (Ba+Ca+Sr) / (Ti+Zr) ratio. b3: Among the intervals that are greater than or equal to half the (Ba+Ca+Sr) / (Ti+Zr) ratio, the value obtained by multiplying the number of continuous intervals extending to the left and right from the average concentration ratio assignment interval of the (Ba+Ca+Sr) / (Ti+Zr) ratio by the interval width of 0.02 is defined as the half-width of the (Ba+Ca+Sr) / (Ti+Zr) ratio. b4: A multilayer ceramic capacitor in which the normalized concentration ratio variation of the Re / (Ti+Zr) ratio, obtained by dividing the full width at half maximum of the (Ba+Ca+Sr) / (Ti+Zr) ratio by the concentration ratio arithmetic mean of the (Ba+Ca+Sr) / (Ti+Zr) ratio, is 3.50 or less.

2. The multilayer ceramic capacitor according to claim 1, wherein the normalized concentration ratio variation of the Re / (Ti+Zr) ratio is 2.80 or less.

3. The multilayer ceramic capacitor according to claim 1 or 2, wherein the normalized concentration ratio variation of the Re / (Ti+Zr) ratio is less than 2.

30.

4. The multilayer ceramic capacitor according to any one of claims 1 to 3, wherein the rare earth element (Re) includes dysprosium (Dy).

5. The multilayer ceramic capacitor according to any one of claims 1 to 4, wherein the perovskite-type oxide comprises at least Ba among Ba, Ca, and Sr.

6. The multilayer ceramic capacitor according to claim 5, wherein the perovskite oxide further comprises at least one of Ca and Sr.

7. The multilayer ceramic capacitor according to any one of claims 1 to 6, wherein the thickness of the dielectric ceramic layer is 3.5 μm or less.

8. The multilayer ceramic capacitor according to any one of claims 1 to 7, wherein the thickness of the dielectric ceramic layer is 2.5 μm or less.

9. The multilayer ceramic capacitor according to any one of claims 1 to 8, wherein the thickness of the dielectric ceramic layer is 1.0 μm or less.

10. The multilayer ceramic capacitor according to any one of claims 1 to 9, wherein the thickness of the dielectric ceramic layer is 0.8 μm or less.

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