Multilayer ceramic capacitor and method for manufacturing a multilayer ceramic capacitor

Abstract

To provide a multilayer ceramic capacitor with high reliability.SOLUTION: A multilayer ceramic capacitor contains: a lamination body; and a pair of side margin parts. The lamination body includes: a plurality of ceramic layers laminated to a first shaft direction; a plurality of inner electrodes that is positioned between the plurality of ceramic layers; and a pair of side surfaces that is vertical to a second shaft orthogonal to the first shaft, and of which an end part in the second shaft direction of the plurality of inner electrodes is positioned. The pair of side margin parts coats a pair of side surfaces. In the pair of side margin parts, at least one of calcium and strontium is contained in an A site. An atomic ratio of calcium in the A site is larger than the plurality of ceramic layers in the case where calcium is contained in the A site, and the atomic ratio of strontium in the A site is larger than the plurality of ceramic layers in the case where strontium is contained in the A site. A plurality of grass particles is scattered into a polycrystalline material, and the atomic ratio of silicon is 1 at% or more and 10 at% or less.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a multilayer ceramic capacitor to which a side margin portion is attached later.

Background Art

[0002] A technique of attaching a side margin portion during the manufacturing process of a multilayer ceramic capacitor is known (see, for example, Patent Document 1). Since this technique can surely cover both end portions of a plurality of internal electrodes even with a thin side margin portion, it is advantageous for miniaturization and large capacitance of the multilayer ceramic capacitor.

[0003] As an example, in the manufacturing method of the multilayer ceramic capacitor described in Patent Document 1, a laminated sheet in which ceramic sheets printed with internal electrodes are laminated is cut, and a plurality of laminates having a cut surface where a plurality of internal electrodes are exposed as a side surface are produced. Then, by punching out the ceramic sheet on the side surface of the laminate, side margin portions are formed on both side surfaces of the laminate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the multilayer ceramic capacitor as described above, due to the stress applied when cutting the laminated sheet, the interval between the end portions of the plurality of internal electrodes tends to be non-uniform on the side surface of the laminate. Therefore, in such a multilayer ceramic capacitor, since an electric field is concentrated at the end portions of the plurality of internal electrodes, defects such as a decrease in insulation resistance are likely to occur.

[0006] In view of the above circumstances, an object of the present invention is to provide a highly reliable multilayer ceramic capacitor. [Means for solving the problem]

[0007] To achieve the above objective, a multilayer ceramic capacitor according to one embodiment of the present invention comprises a laminate and a pair of side margin portions. The laminate comprises a plurality of ceramic layers stacked in the first axial direction, a plurality of internal electrodes located between the plurality of ceramic layers, and a pair of sides perpendicular to a second axis orthogonal to the first axis, on which the ends of the plurality of internal electrodes in the second axial direction are located. The pair of side margins described above cover the pair of sides described above. In the pair of side margins described above, site A contains at least one of calcium and strontium. If site A contains calcium, the atomic ratio of calcium at site A to titanium at site B is greater than that of the multiple ceramic layers described above. If site A contains strontium, the atomic ratio of strontium at site A to titanium at site B is greater than that of the multiple ceramic layers described above. In the pair of side margin regions described above, multiple glass particles mainly composed of silicon are dispersed in the polycrystalline material, and the atomic ratio of silicon to titanium at site B is between 1 at% and 10 at%.

[0008] In this configuration, the breakdown voltage at the sides of the laminate covering the pair of side margins is improved by the action of at least one of the calcium and strontium contained in the A-site of the perovskite polycrystalline material that constitutes the pair of side margins. As a result, even if the electric field is concentrated at the ends of multiple internal electrodes, defects such as a decrease in insulation resistance are less likely to occur in this multilayer ceramic capacitor. Furthermore, in this multilayer ceramic capacitor, the inclusion of an appropriate amount of silicon in the pair of side margins suppresses a decrease in capacitance while achieving high sinterability in the pair of side margins. Therefore, high reliability can be obtained in this multilayer ceramic capacitor.

[0009] In the pair of side margins described above, the atomic ratio of calcium at site A to titanium at site B may be 0.1 at% or more and 10 at% or less. In the pair of side margins described above, the atomic ratio of strontium at site A to titanium at site B may be 0.1 at% or more and 10 at% or less. In the pair of side margins described above, the total atomic ratio of barium, calcium, and strontium at site A to titanium at site B may be 95 at% or more and 110 at% or less. In the pair of side margins described above, the atomic ratio of silicon to titanium at site B may be greater than that of the multiple ceramic layers described above. In the pair of side margins described above, the atomic ratio of silicon to titanium at site B may be greater than the atomic ratio of the total of calcium and strontium at site A to titanium at site B. [Effects of the Invention]

[0010] As described above, the present invention provides highly reliable multilayer ceramic capacitors. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view of a multilayer ceramic capacitor according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view of the multilayer ceramic capacitor shown above, along the line A-A' in Figure 1. [Figure 3] This is a cross-sectional view of the multilayer ceramic capacitor shown above, along the line B-B' in Figure 1. [Figure 4] This flowchart shows the manufacturing method for the multilayer ceramic capacitor described above. [Figure 5] This is a perspective view of the unfired laminate prepared in step S01 of the above manufacturing method. [Figure 6] This is a perspective view of the unfired ceramic body obtained in step S02 of the above manufacturing method. [Modes for carrying out the invention]

[0012] Hereinafter, the multilayer ceramic capacitor 10 according to an embodiment of the present invention will be described with reference to the drawings. In the drawings, an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other are appropriately shown. The X-axis, Y-axis, and Z-axis define a fixed coordinate system fixed to the multilayer ceramic capacitor 10.

[0013] [Basic Configuration of Multilayer Ceramic Capacitor 10] FIGS. 1 to 3 are views showing a multilayer ceramic capacitor 10 according to an embodiment of the present invention. FIG. 1 is a perspective view of the multilayer ceramic capacitor 10. FIG. 2 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along line A-A' of FIG. 1. FIG. 3 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along line B-B' of FIG. 1.

[0014] The multilayer ceramic capacitor 10 includes a ceramic body 11, a first external electrode 14, and a second external electrode 15. The ceramic body 11 is configured as a hexahedron having a pair of end faces orthogonal to the X-axis, a pair of side faces orthogonal to the Y-axis, and a pair of main faces orthogonal to the Z-axis. The external electrodes 14 and 15 cover a pair of end faces of the ceramic body 11.

[0015] All of the pair of end faces, the pair of side faces, and the pair of main faces of the ceramic body 11 are configured as flat surfaces. The flat surface according to the present embodiment may not be a strictly flat surface as long as it is recognized as flat when viewed as a whole. For example, it includes a surface having minute irregularities on the surface or a gentle curved shape existing in a predetermined range.

[0016] The external electrodes 14 and 15 face each other in the X-axis direction with the ceramic body 11 interposed therebetween. The external electrodes 14 and 15 each extend from each end face of the ceramic body 11 to the main face and the side face. As a result, in the external electrodes 14 and 15, both a cross section parallel to the X-Z plane and a cross section parallel to the X-Y plane are U-shaped.

[0017] Note that the shapes of the external electrodes 14 and 15 are not limited to those shown in FIG. 1. For example, the external electrodes 14 and 15 may extend from both end faces of the ceramic body 11 to only one main face, and the cross section parallel to the X-Z plane may be L-shaped. Also, the external electrodes 14 and 15 may not extend to any main face or side face.

[0018] The external electrodes 14 and 15 are formed of a good electric conductor. Examples of the good electric conductor forming the external electrodes 14 and 15 include metals or alloys mainly composed of, for example, copper (Cu), nickel (Ni), tin (Sn), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), and the like. In this embodiment, the main component refers to the component with the highest content ratio.

[0019] The ceramic body 11 has a laminate 16 and a pair of side margin portions 17. The laminate 16 constitutes a pair of main faces and a pair of end faces of the ceramic body 11 and has a pair of side faces F perpendicular to the Y axis. Each of the pair of side margin portions 17 covers the pair of side faces F of the laminate 16 and constitutes a pair of side faces of the ceramic body 11.

[0020] The laminate 16 has a configuration in which a plurality of flat ceramic layers 20 extending along the X-Y plane are laminated in the Z-axis direction. The laminate 16 has a capacitance forming portion 18 and a pair of cover portions 19. The pair of cover portions 19 cover the capacitance forming portion 18 from above and below in the Z-axis direction and constitute a pair of main faces of the ceramic body 11.

[0021] The capacitance forming portion 18 is disposed between the plurality of ceramic layers 20 and has a plurality of first and second internal electrodes 12 and 13 in the form of sheets extending along the X-Y plane. The internal electrodes 12 and 13 are alternately arranged in the Z-axis direction. That is, in the capacitance forming portion 18, the internal electrodes 12 and 13 face each other in the Z-axis direction with the ceramic layer 20 interposed therebetween.

[0022] The first internal electrode 12 is drawn out to the end face covered by the first external electrode 14. On the other hand, the second internal electrode 13 is drawn out to the end face covered by the second external electrode 15. As a result, the first internal electrode 12 is connected only to the first external electrode 14, and the second internal electrode 13 is connected only to the second external electrode 15.

[0023] The internal electrodes 12 and 13 are formed across the entire width of the capacitance forming section 18 in the Y-axis direction, with both ends in the Y-axis direction positioned on both sides F of the laminate 16. As a result, in the ceramic substrate 11, the positions of the ends of the multiple internal electrodes 12 and 13 in the Y-axis direction are aligned within a range of 0.5 μm or less in the Y-axis direction on both sides F of the laminate 16.

[0024] The internal electrodes 12 and 13 are formed from a good electrical conductor. Typical good electrical conductors forming the internal electrodes 12 and 13 include nickel (Ni), but other examples include metals or alloys mainly composed of copper (Cu), palladium (Pd), platinum (Pt), silver (Ag), and gold (Au).

[0025] With this configuration, when a voltage is applied between the first external electrode 14 and the second external electrode 15 in the multilayer ceramic capacitor 10, a voltage is applied to the multiple ceramic layers 20 between the first internal electrode 12 and the second internal electrode 13. As a result, the multilayer ceramic capacitor 10 stores a charge corresponding to the voltage between the first external electrode 14 and the second external electrode 15.

[0026] [Composition of the ceramic layer 20 and the side margin portion 17] (Schematic configuration) In the ceramic body 11 of the multilayer ceramic capacitor 10, multiple ceramic layers 20, a pair of cover portions 19, and a pair of side margin portions 17 are all composed of polycrystalline dielectric ceramics with a perovskite structure. The perovskite structure consists of A sites, B sites, and oxygen (O), and is represented by the general formula ABO3.

[0027] In the ceramic body 11, the polycrystalline materials constituting the multiple ceramic layers 20, the pair of cover portions 19, and the pair of side margin portions 17 are all made of barium titanate (BaTiO3) based materials that easily yield high dielectric constants, that is, they have a perovskite structure containing barium at the A site and titanium at the B site.

[0028] In the multilayer ceramic capacitor 10, the compositions of the polycrystalline materials constituting the multiple ceramic layers 20 and the side margin portion 17 are made to differ from each other. More specifically, the polycrystalline materials constituting the multiple ceramic layers 20 have a composition that prioritizes relative permittivity, while the polycrystalline materials constituting the side margin portion 17 have a composition that prioritizes breakdown voltage.

[0029] In the multilayer ceramic capacitor 10, a large capacitance is obtained by constructing multiple ceramic layers 20 from polycrystalline materials with a high dielectric constant. On the other hand, in the multilayer ceramic capacitor 10, the polycrystalline material constituting the side margin portion 17, which does not contribute to the formation of capacitance, is composed to pursue high breakdown voltage without being concerned with the dielectric constant.

[0030] As a result, in the multilayer ceramic capacitor 10, even if an electric field concentrates at the ends of the internal electrodes 12 and 13 located on the side surface F of the laminate 16, defects such as a decrease in insulation resistance are less likely to occur due to the action of the highly voltage-resistant side margin portion 17. In other words, the multilayer ceramic capacitor 10 can improve reliability without sacrificing capacitance.

[0031] (Detailed configuration) In the polycrystalline material constituting the multiple ceramic layers 20 and side margin portion 17 of the ceramic substrate 11, the composition of the A site of the perovskite structure differs, specifically the amount of calcium used to replace barium in the A site of the perovskite structure. In other words, the amount of calcium titanate (CaTiO3) dissolved in barium titanate differs.

[0032] Calcium titanate has a lower dielectric constant and higher breakdown voltage compared to barium titanate. Therefore, in polycrystalline materials, the more calcium present in the A-site, the lower the dielectric constant becomes, while the breakdown voltage improves. Thus, the balance between dielectric constant and breakdown voltage can be adjusted by controlling the amount of calcium in the A-site.

[0033] In the polycrystalline material constituting the multiple ceramic layers 20 that contribute to the formation of capacitance, it is preferable to reduce the amount of calcium at the A site and to substantially eliminate calcium at the A site. As a result, in the multilayer ceramic capacitor 10, a large capacitance can be obtained due to the action of the multiple ceramic layers 20 composed of polycrystalline material with a high dielectric constant.

[0034] In contrast, the side margin portion 17, which does not contribute to the formation of capacitance, can contain a large amount of calcium in the A-site of the polycrystalline material. Therefore, in the multilayer ceramic capacitor 10, the breakdown voltage of the side margin portion 17 is improved by containing a large amount of calcium in the A-site of the polycrystalline material that constitutes the side margin portion 17.

[0035] Specifically, in the side margin portion 17, the amount of calcium at site A is greater than that of the multiple ceramic layers 20, meaning that the atomic ratio R of calcium at site A is greater than that of the multiple ceramic layers 20. The atomic ratio R of a particular element is based on the number of titanium atoms, that is, the ratio of the number of atoms of that element to the number of titanium atoms contained in site B.

[0036] In the side margin portion 17, it is preferable that the atomic ratio R of calcium at site A is 0.1 at% or more. On the other hand, in the multilayer ceramic capacitor 10, in order to suppress the decrease in capacitance due to the diffusion of calcium from the side margin portion 17 to the multiple ceramic layers 20, it is preferable to keep the atomic ratio R of calcium at site A at 10 at% or less.

[0037] Furthermore, in the side margin portion 17, the greater the amount of calcium at site A, the higher the sintering temperature, meaning the larger the sintering temperature gap with the laminate 16. In the side margin portion 17, the later the sintering timing is compared to the laminate 16, the more pores are formed, making it easier for moisture to penetrate into the laminate 16.

[0038] In contrast, the side margin portion 17 contains silicon (Si). During firing, silicon forms a molten phase as a glass component, which has the effect of lowering the sintering temperature of the side margin portion 17. Therefore, in the multilayer ceramic capacitor 10, the sintering temperature gap between the laminate 16 and the side margin portion 17 can be reduced.

[0039] As a result, in the multilayer ceramic capacitor 10, the sintering timing of the side margin portion 17 can be synchronized with that of the laminate 16, making it less likely for pores to form in the side margin portion 17. Therefore, it is possible to suppress the intrusion of moisture into the laminate 16 side via the pore path in the side margin portion 17.

[0040] In the side margin region 17, the action of silicon results in a structure in which multiple glass particles are dispersed within the polycrystalline material. The multiple glass particles in the side margin region 17 are mainly composed of amorphous material and contain silicon as the main component. In other words, in the side margin region 17, silicon exists not within the polycrystalline material but within the multiple glass particles.

[0041] In the side margin portion 17, multiple glass particles dispersed in the polycrystalline material have the effect of preventing the propagation of cracks that occur in the polycrystalline material. As a result, the occurrence of cracks penetrating in the thickness direction is suppressed in the side margin portion 17, and the intrusion of moisture into the laminate 16 side through cracks can be suppressed.

[0042] In this way, by incorporating silicon into the side margin portion 17 of the multilayer ceramic capacitor 10, moisture resistance is improved, meaning that a decrease in insulation resistance due to moisture intrusion into the inside of the side margin portion 17 becomes less likely. As a result, the multilayer ceramic capacitor 10 can achieve even higher reliability.

[0043] In the side margin portion 17, in order to fully obtain the effects of silicon as described above, it is preferable that the atomic ratio R of silicon to titanium at the B site of the polycrystalline material is 1 at% or more and 3.0 at% or more. In addition, in the multiple ceramic layers 20, it is preferable that the silicon content is less than that of the side margin portion 17 in order to ensure capacitance.

[0044] On the other hand, if the silicon content in the side margin portion 17 is too high, the flexibility becomes excessive, making it difficult to maintain a normal shape, such as impairing the flatness of the outer surface during the manufacturing process. For this reason, it is preferable to keep the atomic ratio R of silicon in the side margin portion 17 to 10 at% or less.

[0045] In this embodiment, the components of the multiple ceramic layers 20 and the side margin portions 17 are evaluated in areas other than the boundary regions where interdiffusion of components occurs. Specifically, the components of the ceramic layer 20 are evaluated in the central region excluding both ends in the Y-axis direction. The components of the side margin portions 17 are evaluated in the region excluding the portion adjacent to the side surface F of the laminate 16.

[0046] (Other embodiments) In the side margin portion 17, strontium may be used instead of calcium as the element to substitute for barium at site A. In other words, strontium titanate (SrTiO3) may be dissolved in barium titanate. With this configuration as well, the same effect as above can be obtained because strontium acts in the same way as calcium.

[0047] In this case, in the multilayer ceramic capacitor 10, in order to achieve both capacitance and reliability, the atomic ratio R of strontium at the A site in the side margin portion 17 needs to be greater than that of the multiple ceramic layers 20. Furthermore, it is preferable that the atomic ratio R of strontium at the A site in the side margin portion 17 is 1 at% or more and 10 at% or less.

[0048] Furthermore, in the side margin portion 17, calcium and strontium may be used in combination as the elements to substitute for barium at site A. In other words, calcium titanate and strontium titanate may be dissolved in barium titanate. With this configuration as well, the same effects as described above can be obtained through the action of calcium and strontium.

[0049] In this case, in the multilayer ceramic capacitor 10, the total atomic ratio R of calcium and strontium at site A in the side margin portion 17 must be greater than the total atomic ratio R of calcium and strontium at site A in the multiple ceramic layers 20. Furthermore, in the side margin portion 17, it is preferable that the total atomic ratio R of calcium and strontium at site A is 1 at% or more and 10 at% or less.

[0050] Furthermore, in all of the above cases, it is preferable that the total atomic ratio R of barium, calcium, and strontium at site A in the side margin portion 17 is 95 at% or more and 110 at% or less. This makes it possible to make the polycrystalline material constituting the side margin portion 17 a more stable perovskite structure.

[0051] [Manufacturing method for multilayer ceramic capacitor 10] Figure 4 is a flowchart showing the manufacturing method of the multilayer ceramic capacitor 10 according to this embodiment. Figures 5 and 6 show the manufacturing process of the multilayer ceramic capacitor 10. The manufacturing method of the multilayer ceramic capacitor 10 will be described below in reference to Figure 4, with appropriate reference to Figures 5 and 6.

[0052] (Step S01: Laminate preparation) In step S01, an unfired laminate 16, as shown in Figure 5, is prepared. The unfired laminate 16 can be made using a laminated sheet in which multiple large ceramic sheets are stacked in the Z-axis direction. A conductive paste for forming internal electrodes 12 and 13 is patterned on the ceramic sheet corresponding to the volume forming section 18.

[0053] The composition of the ceramic sheets constituting the laminated sheet can be determined according to the composition of the multiple ceramic layers 20. Furthermore, in the laminated sheet, the ceramic sheets corresponding to the pair of cover portions 19 may be composed of different components from the ceramic sheets corresponding to the multiple ceramic layers 20, or they may be composed of the same components as, for example, the ceramic sheets corresponding to the side margin portions 17.

[0054] The unfired laminate 16 is obtained by cutting the laminated sheet along the XZ and YZ planes. For cutting the laminated sheet, a cutting device equipped with, for example, a push-cutting blade or a rotary blade can be used. As a result, the laminate 16 has a pair of side surfaces F as cut surfaces where both ends of the internal electrodes 12 and 13 in the Y-axis direction are aligned.

[0055] (Step S02: Formation of side margins) In step S02, a pair of unfired side margins 17 are provided on each of the pair of side surfaces F of the unfired laminate 16 fabricated in step S01. As a result, an unfired ceramic body 11 is obtained in which a pair of side surfaces are formed by the unfired side margins 17, as shown in Figure 6.

[0056] The side margin portion 17 can be formed by any method. For example, the side margin portion 17 can be formed using a ceramic sheet obtained by forming a ceramic slurry into a sheet. In this case, the ceramic sheet can be punched out on the side F of the laminate 16, for example, or it can be pre-cut and attached to the side F of the laminate 16.

[0057] Furthermore, in order to form the side margin portion 17, an unformed ceramic slurry can be used as is, instead of a pre-formed ceramic sheet. In this case, the ceramic slurry can be applied to the side surface F of the laminate 16 by, for example, immersing the side surface F of the laminate 16.

[0058] The composition of the ceramic slurry can be determined according to the composition of the side margin portion 17. For example, in the ceramic slurry, barium titanate powder and calcium oxide (and / or strontium oxide) powder can be used as components constituting the polycrystalline material, and silica powder can be used as a component constituting the glass particles.

[0059] (Step S03: Firing) In step S03, the ceramic body 11 obtained in step S02 is fired to produce the ceramic body 11 shown in Figures 1-3. When barium titanate powder is used as the raw material powder as described above, during the firing process of the ceramic body 11, the barium in the barium titanate is replaced with calcium in the side margin portion 17.

[0060] In other words, during firing, in the side margin portion 17, silicon first melts while incorporating the barium in the barium titanate as a glass component. Then, calcium is deposited in the A-site where the barium was removed from the barium titanate. In this way, the action of silicon allows calcium to be disposed in the A-site of the barium titanate.

[0061] In the pair of side margin portions 17, it is preferable to add a sufficient amount of silicon in order to replace the entire amount of at least one of the added calcium and strontium with barium of barium titanate. Specifically, it is preferable that the atomic ratio R of silicon is greater than the combined atomic ratio R of calcium and strontium at site A.

[0062] (Step S04: External electrode formation) In step S04, external electrodes 14 and 15 are formed on both ends of the ceramic body 11 fired in step S03 in the X-axis direction, thereby fabricating the multilayer ceramic capacitor 10 shown in Figures 1 to 3. The method for forming the external electrodes 14 and 15 in step S04 can be arbitrarily selected from known methods.

[0063] As a result of the above, the multilayer ceramic capacitor 10 shown in Figures 1 to 3 is completed. In this manufacturing method, a side margin portion 17 is formed on the side surface F of the laminate 16 in which the internal electrodes 12 and 13 are exposed, so that the positions of the ends of the multiple internal electrodes 12 and 13 in the ceramic body 11 in the Y-axis direction are aligned within a range of 0.5 μm or less in the Y-axis direction.

[0064] [Examples] Examples 1-3 consisted of multilayer ceramic capacitors with different ceramic substrate configurations. The samples in each of Examples 1-3 shared a common configuration except for those specifically described below. For the element substituting the barium at the A-site of barium titanate, calcium was used in Examples 1 and 3, while strontium was used in Example 2.

[0065] (Example 1) Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-3 were prepared in which the atomic ratio R of calcium at the A site differed in a pair of side margins and multiple ceramic layers. The atomic ratio R of calcium at the A site in a pair of side margins and multiple ceramic layers for each sample is shown in Table 1.

[0066] Each sample was evaluated for insulation resistance and capacitance. For insulation resistance, samples with an insulation resistance of 100 MΩ or higher were considered good. For capacitance, 4.0 μF was used as the standard, and samples with a capacitance between 3.2 μF and 4.8 μF (within ±20% of 4.0 μF) were considered good. The evaluation results for insulation resistance and capacitance are shown in Table 1.

[0067] [Table 1]

[0068] As shown in Table 1, all samples from Examples 1-1 to 1-4 were judged to be good quality. However, in the sample from Example 1-4, where the atomic ratio R of calcium at site A in the side margin exceeded 10 at%, the capacitance was slightly lower compared to the samples from Examples 1-1 to 1-3.

[0069] On the other hand, the sample related to Comparative Example 1-1 had an insulation resistance of less than 100 MΩ, resulting in a judgment that it was a defective product. This is thought to be because, in the sample related to Comparative Example 1-1, neither the side margin portion nor the ceramic layer contained calcium, causing a decrease in insulation resistance due to electrolysis concentration.

[0070] Furthermore, in the samples related to Comparative Examples 1-2 and 1-3, the capacitance was less than 3.2 μF, resulting in a determination that they were defective. This is thought to be because, in the samples related to Comparative Examples 1-2 and 1-3, the presence of calcium equal to or greater than that in the side margin portion of multiple ceramic layers caused a decrease in capacitance.

[0071] (Example 2) Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-3 were prepared in which the atomic ratio R of strontium at the A site differed in a pair of side margins and multiple ceramic layers. The atomic ratio R of strontium at the A site in a pair of side margins and multiple ceramic layers for each sample is shown in Table 2.

[0072] Each sample was evaluated for insulation resistance and capacitance. For insulation resistance, samples with an insulation resistance of 100 MΩ or higher were judged as good. For capacitance, 4.0 μF was used as the standard, and samples with a capacitance between 3.2 μF and 4.8 μF (within ±20% of 4.0 μF) were judged as good. The evaluation results for insulation resistance and capacitance are shown in Table 2.

[0073] [Table 2]

[0074] As shown in Table 2, all samples from Examples 2-1 to 2-4 were judged to be good quality. However, in the sample from Example 2-4, where the atomic ratio R of strontium at site A in the side margin exceeded 10 at%, the capacitance was slightly lower compared to the samples from Examples 2-1 to 2-3.

[0075] On the other hand, the sample related to Comparative Example 2-1 had an insulation resistance of less than 100 MΩ, resulting in a determination that it was a defective product. This is thought to be because, in the sample related to Comparative Example 2-1, neither the side margin portion nor the ceramic layer contained strontium, causing a decrease in insulation resistance due to electrolysis concentration.

[0076] Furthermore, in the samples related to Comparative Examples 2-2 and 2-3, the capacitance was less than 3.2 μF, resulting in a determination that they were defective. This is thought to be because, in the samples related to Comparative Examples 1-2 and 1-3, the presence of strontium in multiple ceramic layers equal to or greater than that in the side margin area caused a decrease in capacitance.

[0077] (Example 3) Samples were prepared for configurations A1-A8, B1-B8, and C1-C8, each with varying atomic ratios of calcium and silicon at site A in the side margin. The atomic ratio of calcium was set to 0 at% for configurations A1-A8, 2 at% for configurations B1-B8, and 5 at% for configurations C1-C8.

[0078] The atomic ratios R for each of the compositions A1 to A8 are shown in Table 3. Compositions A1 to A8 are comparative examples in that they do not contain calcium in the side margin. In addition, the atomic ratio R of silicon in the side margin was varied in various ways within the range of 0.1 at% to 12 at% for compositions A1 to A8.

[0079] The atomic ratios R for each of the configurations B1 to B8 are shown in Table 4. In configurations B1 to B8, the atomic ratio R of silicon in the side margin was varied in various ways. Configurations B2 to B7 are all examples. On the other hand, configuration B1, in which the atomic ratio R of silicon is less than 1 at%, and configuration B8, in which the atomic ratio R of silicon is greater than 10 at%, are both comparative examples.

[0080] The atomic ratios R for each of the compositions C1 to C8 are shown in Table 5. In compositions C1 to C8, the atomic ratio R of silicon in the side margin was varied in various ways. Compositions C2 to C7 are all examples. On the other hand, composition C1, in which the atomic ratio R of silicon is less than 1 at%, and composition C8, in which the atomic ratio R of silicon is greater than 10 at%, are both comparative examples.

[0081] For each component, the appearance of the side margin, the pore ratio of the side margin, and the insulation failure rate were evaluated. Regarding the appearance of the side margin, the shape of the side margin was observed using a laser microscope for each component. Samples that were normal were evaluated as "a," and samples that were abnormal were evaluated as "b." Specifically, samples in which the Y-axis dimension of the side margin was 25% or more of the central part in the Z-axis direction at a position adjacent to the inner electrode located in the outermost layer in the Z-axis direction were judged to be normal.

[0082] To determine the pore ratio of the side margin, for example, a microstructural image of the cross-section of the side margin obtained by a scanning electron microscope (SEM) can be used. Specifically, the pore ratio of the side margin can be determined as the ratio of the area occupied by the cross-section of pores in a predetermined region of the microstructural image.

[0083] In evaluating the insulation failure rate, 1000 samples for each configuration were subjected to a humidity resistance test, held for 100 hours in an environment of 85°C and 85% humidity. For each configuration, the insulation failure rate was defined as the percentage of samples out of 1000 that had an insulation resistance of less than 1 MΩ after the humidity resistance test. The evaluation results for each configuration are shown in Tables 3 to 5.

[0084] [Table 3]

[0085] [Table 4]

[0086] [Table 5]

[0087] As shown in Table 3, in configurations A1 to A8, which do not contain calcium at site A in the side margin, the pore ratio was low regardless of the amount of silicon, and not a single sample exhibited an insulation resistance of less than 1 MΩ after the humidity resistance test. In other words, it can be seen that the pore ratio problem does not occur in configurations that do not contain calcium at site A.

[0088] On the other hand, as shown in Tables 4 and 5, in configurations containing calcium at the A site in the side margin, there was a tendency for the pore ratio to decrease as the atomic ratio R of silicon in the side margin increased. In particular, for silicon atomic ratio R of 1 at% or higher, the insulation failure rate was significantly suppressed, and at 3 at% or higher, insulation failure almost did not occur.

[0089] Furthermore, in configurations A8, B8, and C8, the appearance evaluation was "B," and a normal-shaped side margin portion could not be obtained. This is thought to be because, in the samples related to configurations A8, B8, and C8, where the atomic ratio R of silicon in the side margin portion exceeded 10 at%, the flexibility of the side margin portion was too high, preventing it from maintaining a normal shape.

[0090] [Other embodiments] Although embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the embodiments described above and can be modified in various ways.

[0091] For example, the composition of a polycrystalline perovskite structure comprising multiple ceramic layers and a pair of side margins can be designed in various ways depending on the desired performance. In other words, the polycrystalline material may contain elements other than barium, calcium, and strontium at site A, and elements other than titanium at site B. [Explanation of Symbols]

[0092] 10…Multilayer ceramic capacitor 11…Ceramic body 12,13…Internal electrode 14,15...External electrode 16…Laminate 17... Side margin section 18...Capacitance forming part 19...Cover part 20…Ceramic layer

Claims

1. The laminate comprises a plurality of ceramic layers stacked in the first axial direction, a plurality of internal electrodes located between the plurality of ceramic layers, a pair of side surfaces perpendicular to a second axis orthogonal to the first axis, on which the ends of the plurality of internal electrodes in the second axial direction are located, and a pair of side margins covering the pair of side surfaces. The aforementioned multiple ceramic layers are composed of polycrystalline materials with a perovskite structure, containing barium at site A, substantially free of calcium and strontium, and containing titanium at site B. The pair of side margin portions are composed of a polycrystalline perovskite structure containing at least one of calcium and strontium at site A and titanium at site B. In the pair of side margin portions, If calcium is present at site A, the atomic ratio of calcium at site A to titanium at site B is greater than that of the multiple ceramic layers; if strontium is present at site A, the atomic ratio of strontium at site A to titanium at site B is greater than that of the multiple ceramic layers. Multiple glass particles, mainly composed of silicon and containing barium, are dispersed in a polycrystalline material, and the atomic ratio of silicon to titanium at the B site is 1 at% to 10 at%. Multilayer ceramic capacitor.

2. A multilayer ceramic capacitor according to claim 1, In the pair of side margin portions, the atomic ratio of calcium at site A to titanium at site B is 0.1 at% or more and 10 at% or less. Multilayer ceramic capacitor.

3. A multilayer ceramic capacitor according to claim 1 or 2, In the pair of side margin portions, the atomic ratio of strontium at site A to titanium at site B is 0.1 at% or more and 10 at% or less. Multilayer ceramic capacitor.

4. A multilayer ceramic capacitor according to any one of claims 1 to 3, In the pair of side margin portions, the total atomic ratio of barium, calcium, and strontium at site A to titanium at site B is 95 at% or more and 110 at% or less. Multilayer ceramic capacitor.

5. A multilayer ceramic capacitor according to any one of claims 1 to 4, In the pair of side margins, the atomic ratio of silicon to titanium at site B is greater than that of the multiple ceramic layers. Multilayer ceramic capacitor.

6. A multilayer ceramic capacitor according to any one of claims 1 to 5, In the pair of side margins, the atomic ratio of silicon to titanium at site B is greater than the combined atomic ratio of calcium and strontium at site A to titanium at site B. Multilayer ceramic capacitor.

7. A method for manufacturing a multilayer ceramic capacitor, comprising: a plurality of ceramic layers stacked in a first axial direction; a plurality of internal electrodes located between the plurality of ceramic layers; a pair of side surfaces perpendicular to a second axis orthogonal to the first axis, on which the ends of the plurality of internal electrodes in the second axial direction are located; and a pair of side margins covering the pair of side surfaces, The process of forming the aforementioned multiple ceramic layers involves stacking ceramic sheets made from a polycrystalline material with a perovskite structure consisting of a barium-containing A site and a titanium-containing B site as raw material powder, The process of forming the pair of side margins using a ceramic sheet or ceramic slurry made from a perovskite polycrystalline material consisting of an A site containing barium and substantially free of calcium and strontium, and a B site containing titanium, and silica powder and at least one of calcium oxide and strontium oxide powder as raw material powders, In the pair of side margin portions, a sintering process is performed in which silicon derived from the silica powder melts in the polycrystalline body while incorporating the barium of the A site as a glass component, thereby dispersing a plurality of glass particles mainly composed of silicon and containing barium, and the A site from which the barium has been removed is replaced with a polycrystalline body in which at least one of calcium derived from calcium oxide and strontium derived from strontium oxide is substituted, Includes, The atomic ratio of silicon to titanium at site B is between 1 at% and 10 at%. A method for manufacturing multilayer ceramic capacitors.

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