Multilayer ceramic electronic components

Abstract

To provide a multilayer ceramic electronic component that can suppress the deterioration of moisture resistance. [Solution] The multilayer ceramic electronic component comprises a laminate in which a plurality of dielectric layers 11 and a plurality of internal electrode layers 12 are alternately stacked. The plurality of dielectric layers 11 mainly consist of first crystal particles 30 made of barium titanate having a perovskite structure represented by the general formula ABO3. At least one of the plurality of internal electrode layers has a break, and second crystal particles 40 having an elemental ratio of barium to titanium of 0.70 or less are arranged in the break.

Description

[Technical Field]

[0001] This invention relates to multilayer ceramic electronic components. [Background technology]

[0002] Multilayer ceramic electronic components, such as multilayer ceramic capacitors (MLCCs), are used in high-frequency communication systems, including those found in mobile phones. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2011-124429 [Patent Document 2] Japanese Patent Publication No. 2017-011172 [Overview of the project] [Problems that the invention aims to solve]

[0004] A multilayer ceramic capacitor (MLCC) comprises a laminate of dielectric layers made of a dielectric porcelain composition having capacitance, a cover layer sandwiching the laminate from above and below, and side margins sandwiching the laminate from the sides. In the cover layer and side margins, the amount of diffusion from the internal electrode layer in the laminate is small, resulting in a higher densification temperature compared to the dielectric layer, and insufficient densification, leading to problems with moisture resistance. There are methods to promote densification of the cover layer and side margins by adding Si (silicon) or Mn (manganese) to the cover layer and side margins (Patent Documents 1 and 2), but manganese and silicon diffuse into the active part, causing a decrease in dielectric constant and abnormal grain growth, resulting in reduced reliability.

[0005] This invention has been made in view of the above problems, and aims to provide a multilayer ceramic electronic component that can suppress the deterioration of moisture resistance.

Means for Solving the Problem

[0006] The multilayer ceramic electronic component according to the present invention includes a laminate in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated. The plurality of dielectric layers mainly comprise first crystal particles made of barium titanate having a perovskite structure represented by the general formula ABO3. At least one of the plurality of internal electrode layers has a discontinuous portion, and second crystal particles having an elemental ratio of barium to titanium of 0.70 or less are disposed at the discontinuous portion.

[0007] In the above multilayer ceramic electronic component, the second crystal particles are BaTi2O5, BaTi4O9, BaTi5O , BaTi6O 13 , Ba4Ti 11 O 26 , Ba4Ti 12 O 27 , Ba4Ti 13 O 30 , or Ba6Ti 17 O 40 and may be at least one selected therefrom.

[0008] ​​​​​​​​​​​​​​​​According to the present invention, it is possible to provide a multilayer ceramic electronic component that can suppress the deterioration of moisture resistance. [Brief explanation of the drawing]

[0012] [Figure 1] This is a partial cross-sectional perspective view of a multilayer ceramic capacitor. [Figure 2] This is a cross-sectional view along line AA in Figure 5. [Figure 3] Figure 5 is a cross-sectional view along line BB. [Figure 4] (a) and (b) are enlarged cross-sectional views near the external electrode 20a. [Figure 5] This is a schematic cross-sectional view of the dielectric layer. [Figure 6] This figure illustrates the unit cell of a crystal grain having a perovskite-type structure. [Figure 7] This is a schematic cross-sectional view of the dielectric layer and the internal electrode layer. [Figure 8] This figure illustrates an example of a 20 μm × 20 μm region located in the center of a cross-section of a multilayer ceramic capacitor polished in the BB direction in Figure 1. [Figure 9] This diagram illustrates a flow chart of the manufacturing process for multilayer ceramic capacitors. [Figure 10] (a) and (b) are diagrams illustrating the internal electrode formation process. [Figure 11] This is a diagram illustrating the crimping process. [Modes for carrying out the invention]

[0013] The embodiments will be described below with reference to the drawings.

[0014] (Embodiment) Figure 1 is a partial cross-sectional perspective view of a multilayer ceramic capacitor 100 according to an embodiment. Figure 2 is a cross-sectional view taken along line AA in Figure 1. Figure 3 is a cross-sectional view taken along line BB in Figure 1. As illustrated in Figures 1 to 3, the multilayer ceramic capacitor 100 comprises a base body 10 having a substantially rectangular parallelepiped shape and external electrodes 20a and 20b provided on two opposing end faces of either the base body 10. Of the four faces of the base body 10 other than the two end faces, the two faces other than the top and bottom faces in the stacking direction are referred to as side faces. The external electrodes 20a and 20b extend to the top, bottom, and two side faces of the base body 10 in the stacking direction. However, the external electrodes 20a and 20b are spaced apart from each other.

[0015] In Figures 1 to 3, the Z-axis direction (first direction) is the stacking direction, and is the direction in which each internal electrode layer faces another. The X-axis direction (second direction) is the length direction of the base body 10, and is the direction in which the two end faces of the base body 10 face each other, and is the direction in which the external electrode 20a and external electrode 20b face each other. The Y-axis direction (third direction) is the width direction of the internal electrode layer, and is the direction in which the two sides of the base body 10 (excluding the two end faces) face each other. The X-axis direction, the Y-axis direction, and the Z-axis direction are mutually orthogonal.

[0016] The base body 10 has a structure in which dielectric layers 11 containing a ceramic material that functions as a dielectric and internal electrode layers 12 are alternately stacked. The edges of each internal electrode layer 12 are alternately exposed to the end face of the base body 10 where the external electrode 20a is provided and the end face where the external electrode 20b is provided. As a result, each internal electrode layer 12 is alternately electrically connected to the external electrode 20a and the external electrode 20b. Consequently, the multilayer ceramic capacitor 100 has a structure in which multiple dielectric layers 11 are stacked via internal electrode layers 12. Furthermore, in the laminate of dielectric layers 11 and internal electrode layers 12, the outermost layer in the stacking direction is the internal electrode layer 12, and the top and bottom surfaces of the laminate are covered by a cover layer 13. The cover layer 13 mainly consists of a ceramic material. For example, the cover layer 13 may have the same composition as the dielectric layer 11 or a different composition. Furthermore, the configuration is not limited to that shown in Figures 1 to 3, as long as the internal electrode layer 12 is exposed on two different surfaces and is electrically connected to different external electrodes.

[0017] The dimensions of the multilayer ceramic capacitor 100 are, for example, 0.25 mm in length, 0.125 mm in width, and 0.125 mm in height, or 0.4 mm in length, 0.2 mm in width, and 0.2 mm in height, or 0.6 mm in length, 0.3 mm in width, and 0.3 mm in height, or 1.0 mm in length, 0.5 mm in width, and 0.5 mm in height, or 3.2 mm in length, 1.6 mm in width, and 1.6 mm in height, or 4.5 mm in length, 3.2 mm in width, and 2.5 mm in height, but are not limited to these dimensions.

[0018] The internal electrode layer 12 is mainly composed of base metals such as nickel (Ni), copper (Cu), tin (Sn), or alloys containing these. Precious metals such as platinum (Pt), palladium (Pd), silver (Ag), and gold (Au), or alloys containing these, may also be used as the internal electrode layer 12. The average thickness per layer of the internal electrode layer 12 in the Z-axis direction is, for example, 0.1 μm to 3.0 μm, 0.1 μm to 2.0 μm, or 0.1 μm to 1.0 μm. The thickness of the internal electrode layer 12 can be measured by observing the cross-section of the multilayer ceramic capacitor 100 with an SEM (scanning electron microscope), measuring the thickness at 10 points for each of 10 different internal electrode layers 12, and deriving the average value of all measurement points.

[0019] The dielectric layer 11 mainly consists of a ceramic material having a perovskite structure represented by the general formula ABO3. Note that this perovskite structure is an ABO3 structure that deviates from the stoichiometric composition. 3-α This includes the following. In this embodiment, barium titanate (BaTiO3) is used as the ceramic material. For example, the dielectric layer 11 contains 90 at% or more barium titanate. The thickness of the dielectric layer 11 is, for example, 0.1 μm to 10.0 μm, 0.1 μm to 5.0 μm, or 0.1 μm to 2.0 μm. The thickness of the dielectric layer 11 can be measured by observing the cross-section of the multilayer ceramic capacitor 100 with an SEM (scanning electron microscope), measuring the thickness at 10 points for each of 10 different dielectric layers 11, and deriving the average value of all measurement points.

[0020] The dielectric layer 11 may contain additives. Examples of additives to the dielectric layer 11 include oxides of zirconium (Zr), hafnium (Hf), magnesium (Mg), manganese (Mn), molybdenum (Mo), vanadium (V), chromium (Cr), rare earth elements (yttrium (Y), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), and ytterbium (Yb)), or oxides containing cobalt (Co), nickel (Ni), lithium (Li), boron (B), sodium (Na), potassium (K), or silicon (Si), or glass containing cobalt, nickel, lithium, boron, sodium, potassium, or silicon.

[0021] As illustrated in Figure 2, the region where the internal electrode layer 12 connected to the external electrode 20a and the internal electrode layer 12 connected to the external electrode 20b face each other is a region in the multilayer ceramic capacitor 100 where capacitance is generated. Therefore, this region where capacitance is generated is referred to as the capacitance section 14. In other words, the capacitance section 14 is a region where adjacent internal electrode layers 12 connected to different external electrodes face each other.

[0022] The region where internal electrode layers 12 connected to external electrode 20a face each other without being connected to an internal electrode layer 12 connected to external electrode 20b is called the end margin 15. Similarly, the region where internal electrode layers 12 connected to external electrode 20b face each other without being connected to an internal electrode layer 12 connected to external electrode 20a is also called the end margin 15. In other words, the end margin 15 is the region where internal electrode layers 12 connected to the same external electrode face each other without being connected to an internal electrode layer 12 connected to a different external electrode. The end margin 15 is a region where no capacitance is generated.

[0023] As illustrated in Figure 3, in the element 10, the side margin 16 is a region provided to cover the two side edges (the edges in the Y-axis direction) of the dielectric layer 11 and the internal electrode layer 12. In other words, the side margin 16 is a region provided outside the capacitance portion 14 in the Y-axis direction. The side margin 16 is also a region that does not generate capacitance.

[0024] Figure 4(a) is an enlarged cross-sectional view near the external electrode 20a. Figure 4(b) is an enlarged cross-sectional view near the external electrode 20b. Hatches are omitted in Figures 4(a) and 4(b). As illustrated in Figures 4(a) and 4(b), the external electrodes 20a and 20b have a structure in which a plating layer 22 is provided on a base layer 21. The base layer 21 mainly consists of nickel, copper, etc. The base layer 21 may also contain ceramic particles as a co-material, or it may contain glass components. The plating layer 22 mainly consists of metals such as nickel, copper, aluminum, zinc, tin, or alloys of two or more of these. The plating layer 22 may be a plating layer of a single metal component, or it may be multiple plating layers of different metal components. For example, the plating layer 22 has a structure in which a first plating layer 23, a second plating layer 24, and a third plating layer 25 are formed in order from the base layer 21 side. The first plating layer 23 is, for example, a copper plating layer. The second plating layer 24 is, for example, a nickel plating layer. The third plating layer 25 is, for example, a tin plating layer.

[0025] Figure 5 is a schematic cross-sectional view of the dielectric layer 11. As illustrated in Figure 5, the dielectric layer 11 has a structure in which a plurality of first crystal grains 30 constituting the main phase are sintered. For example, the dielectric layer 11 may have one first crystal grain 30 in the thickness direction, or it may have a structure in which a plurality of first crystal grains 30 are continuous via grain boundaries, as shown in Figure 5. The first crystal grains 30 may be barium titanate, or they may be barium titanate in which other elements are solid-solved.

[0026] The multilayer ceramic capacitor 100 according to this embodiment has a configuration that can suppress a decrease in reliability while maintaining the moisture resistance of the cover layer 13 and the side margin 16. Details will be described below.

[0027] The first crystal grain 30 described in Figure 5 is a crystal grain of barium titanate (BaTiO3) having a perovskite structure. A crystal grain having a perovskite structure has a unit cell as illustrated in Figure 6. This unit cell has A sites located at the vertices of the lattice, O sites located at the center of the lattice faces, and B sites located in an octahedron with the O sites as vertices. In the perovskite structure, alkaline earth metals that can take divalent cations, such as barium (Ba), strontium (Sr), and calcium (Ca), are arranged at the A sites, and metal atoms that can take tetravalent cations, such as hafnium (Hf), zirconium (Zr), and titanium (Ti), are arranged at the B sites. In this embodiment, barium is arranged at the A sites and titanium is arranged at the B sites, and at least one of the A sites and B sites may be substituted by the added elements.

[0028] The perovskite structure allows for compositional formulas that deviate from stoichiometric compositions. That is, the ratio of the A-site element to the B-site element does not necessarily have to be 1:1, and defects may be generated as long as they maintain the perovskite structure. Defects may also be generated in the oxygen atom. For example, compositional formula A α BO 3-β In this case, compositions in the range of 0.98 ≤ α ≤ 1.01 and 0 ≤ β ≤ 0.20 are permissible.

[0029] However, the formation of oxygen vacancies, for example, can reduce resistivity or cause ionic conductivity, leading to a decrease in electrical lifespan and increased dielectric loss when used as a multilayer ceramic capacitor, making it impractical in some cases. For this reason, the first crystal grain 30 having a perovskite structure may optionally contain at least one of the first transition elements: scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), and zinc (Zn). This makes it possible to improve resistivity, increase electrical lifespan, and reduce dielectric loss relative to capacitance.

[0030] Furthermore, the first crystal grain 30 may optionally contain at least one of the second transition elements: yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), and silver (Ag). This makes it possible to improve resistivity, increase electrical lifetime, and reduce dielectric loss relative to capacitance.

[0031] Furthermore, the first crystal grain 30 may optionally contain at least one of the following third transition elements: 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), lutetium (Lu), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au). This makes it possible to improve resistivity, increase electrical lifetime, and reduce dielectric loss relative to capacitance.

[0032] Figure 7 is a schematic cross-sectional view of the dielectric layer 11 and the internal electrode layer 12. As illustrated in Figure 7, in cross-sections including the Z-axis direction (e.g., XZ cross-section, YZ cross-section, etc.), a discontinuity is present in at least a portion of the internal electrode layer 12. A discontinuity is a gap that exists between a portion of the internal electrode layer 12 and other portions of the internal electrode layer 12 in either direction of the XY plane. Second crystal particles 40 are arranged in this discontinuity of the internal electrode layer 12. Specifically, the second crystal particles 40 are arranged in the discontinuity of the internal electrode layer 12 such that they are in contact with any of the first crystal particles 30 of one of the dielectric layers 11 via grain boundaries, and in contact with any of the first crystal particles 30 of adjacent dielectric layers 11 via grain boundaries. Preferably, the second crystal particles 40 are arranged across the entire width of the discontinuity so that they are in contact with a portion of the internal electrode layer 12 and also in contact with other portions of the internal electrode layer 12.

[0033] If a break occurs in the internal electrode layer 12 and this break becomes a void, moisture may penetrate into the void from the outside, potentially reducing moisture resistance. Reduced moisture resistance may lead to deterioration of insulation. In contrast, in this embodiment, by arranging the second crystalline particles 40, which have insulating properties, in the break in the internal electrode layer 12, moisture penetration can be suppressed, and deterioration of insulation can be suppressed. It is assumed that the shortest distance of the break in the internal electrode layer 12 in the XY plane is between 0.1 μm and 20.0 μm.

[0034] If the configuration suppresses the decrease in moisture resistance in the capacitance section 14, the amount of silicon, manganese, and other elements that promote densification added to the cover layer 13 and side margin 16 can be reduced, or it may even be possible to not add silicon, manganese, and other elements at all. Therefore, for example, it is possible to make the ceramic components of the dielectric layer 11 and the ceramic components of the cover layer 13 and side margin 16 the same composition.

[0035] The second crystal grain 40 is a barium titanate-based composite oxide produced when a titanium-based additive (e.g., titanium oxide) is used with barium titanate, and has an elemental ratio (ratio of the number of elements) of barium to titanium of 0.70 or less. Examples of the second crystal grain 40 include BaTi2O5, BaTi4O9, and BaTi5O 11 BaLi6O 13 Ba4Ru 11 O 26 Ba4Ru 12 O 27 Ba4Ru 13 O 30 Ba6Lo 17 O 40 These are some examples.

[0036] The second crystal grain 40 is Ba4Ti 11 O 26 Preferably, the barium titanate composite oxide is monoclinic, with a space group of C2 / m, and lattice constants of a=15.160Å, b=3.893Å, c=9.093Å, and β=98.6°. This is because the ratio of barium to titanium in this barium titanate composite oxide is relatively close to 1, and it is easy to intentionally precipitate it without using a large amount of titanium-based additives. This barium titanate composite oxide is described, for example, in the non-patent literature Acta Cryst. (1979). B35, 1590-1593.

[0037] A more preferred example of the second crystal grain 40 is Ba4Ti 11 O 26 In contrast, it is desirable that manganese is dissolved in the defect site and occupies it, or that some of the titanium is replaced. As is clear from the above non-patent literature, Ba4Ti 11 O 26 This material has a crystal structure in which defects occur at some of the titanium sites. Therefore, at the defect locations, titanium is more likely to change from a tetravalent cation to a trivalent cation, resulting in a decrease in resistivity. The presence of manganese in solid solution is effective in compensating for this.

[0038] The fact that the second crystal grain 40 is positioned at the break in the internal electrode layer 12 can be confirmed by the following procedure.

[0039] First, the diffraction line profile of the dielectric layer 11 to be examined, or the powder obtained by grinding the dielectric layer 11, is measured using an X-ray diffractometer (XRD) that uses Cu-Kα rays. The grinding method for obtaining the powder is not particularly limited, and a hand mill (mortar and pestle) can be used. When measuring the diffraction profile of the ceramics constituting the multilayer ceramic capacitor 100, the electrodes and coatings formed on the surface of the element, and parts of the multilayer ceramic capacitor 100 other than the dielectric layer 11 are removed to expose the surface of the dielectric layer 11. This exposure method is not particularly limited, and methods such as cutting or polishing the element can be employed. Furthermore, when measuring the diffraction profile of the powder of the dielectric layer 11 constituting the multilayer ceramic capacitor 100, it is more preferable to grind it after removing the external electrodes 20a, 20b and coatings formed on the element, and parts of the multilayer ceramic capacitor 100 other than the dielectric layer 11.

[0040] Next, in the obtained diffraction profile, the percentage of the strongest diffraction line intensity from other structures relative to the strongest diffraction line intensity from the perovskite structure is calculated. If this percentage is 10% or less, it is determined that the dielectric layer 11 under investigation is composed of a main phase having a perovskite structure. Note that when the surface of the dielectric layer 11 of the multilayer ceramic capacitor 100 is exposed using the above method, or when XRD measurements are performed on the pulverized powder, peaks from the external electrodes 20a, 20b, the internal electrode layer 12, and the materials constituting the coating may also be detected. In such cases, these should be excluded before calculating the ratio of diffraction line intensities as described above.

[0041] Next, we focus on peaks other than those originating from the perovskite structure to identify the crystalline phase. Ideally, crystalline phase identification should be confirmed by searching the PDF (Powder Diffraction File) published by ICDD (International Centre for Diffraction Data; Pennsylvania, USA) to determine if crystalline grains are present. Ba4Ti is a suitable example. 11 O 26 In this case, the generation can be evaluated by identifying it by referring to PDF-01-083-1459.

[0042] Next, in order to determine that the crystal grains consist of a barium titanate-based composite oxide in which the elemental ratio of barium to titanium is 0.70 or less, and that the second crystal grains are located at the break in the internal electrode layer, the following method is used.

[0043] First, the surface of the dielectric layer 11 is exposed. The method of exposure is not particularly limited, and methods such as cutting or polishing the element can be employed. At this time, in order to observe the internal ceramic structure sufficiently, it is preferable to obtain a smooth surface that can be judged as a mirror surface by ultimately using a diamond paste of 2 μm or less.

[0044] Next, the composition and deposition location of the second crystal grain 40 are identified using an energy-dispersive X-ray spectrometer (EDS) or wavelength-dispersive X-ray spectrometer (WDS) mounted on a scanning electron microscope (SEM) or transmission electron microscope (TEM), an electron probe microanalyzer (EPMA), and laser-irradiated inductively coupled plasma mass spectrometry (LA-ICP-MS).

[0045] For example, in EDS measurements, the titanium K-line intensity is simply determined by the K-line intensity relative to the barium K-line or L-line, or the manganese K-line. More specifically, corrections (ZAF correction) are performed on these intensities, taking into account atomic number effects, absorption effects, and fluorescence excitation effects, to calculate the ratio of each element to the titanium element content, and these are then used as the ratio of each element.

[0046] When performing EDS measurements, particularly with barium's Lα line and titanium's Kα line, the energy peaks are close together, making it difficult to adequately compare elemental content. Therefore, it is desirable to obtain sufficient intensity for barium's Lβ2 and LIIIab lines, which do not overlap peaks, during the measurement. Specifically, it is desirable that the intensity at these peaks be 10,000 counts or more. In this case, the intensity of the characteristic X-ray from barium can be identified, and the elemental content can be calculated. Even if the barium Lα line and the titanium Kα line overlap, the intensity of the titanium Kα line can be identified, and the elemental content can be evaluated with high accuracy.

[0047] When the elemental ratio of barium to titanium obtained by the above method is 0.70 or less, the crystal grain is determined to be the second crystal grain 40. In other words, it is determined to be one of the above barium titanate composite oxides when the elemental ratio of barium to titanium is small compared to the barium titanate present in the surrounding area. In this case, when using SEM during observation, the crystal grain is characterized by being observed as darker and having relatively lower brightness compared to barium titanate in the backscattered electron image (BSE image). Furthermore, a more preferable determination is made by identifying the crystal grain by evaluating the diffraction profile using XRD. Next, in more detail, the area determined to be a crystal grain is cut out as a sample for transmission electron microscopy (TEM) observation, and the diffraction pattern obtained using limited-field diffraction is compared with data from known literature to determine whether it is BaTi2O5, BaTi4O9, or BaTi5O 11 BaLi6O13 Ba4Ru 11 O 26 Ba4Ru 12 O 27 Ba4Ru 13 O 30 , or Ba6Ti 17 O 40 This checks whether it can be determined as such. This extraction can be performed using a FIB device or similar equipment.

[0048] Next, the area ratio of the second crystal grains will be explained. There is no particular need to limit the lower limit of the area ratio occupied by the second crystal grains 40 in the cross-section, but if the area ratio of the second crystal grains 40 is too large, a large amount of the second crystal grains 40 may be present inside the dielectric layer 11. In this case, the dielectric constant of the dielectric layer 11 may decrease. Therefore, it is preferable to set an upper limit on the area ratio of the second crystal grains 40 in the cross-section. In this embodiment, it is preferable that the area ratio occupied by the second crystal grains in a 20 μm × 20 μm region located in the center of the cross-section of the multilayer ceramic capacitor 100 polished in the BB direction in Figure 1 is 50% or less, more preferably 10% or less, and even more preferably 5.0% or less. The area ratio of the second crystal grains 40 in the cross-section can be measured, for example, by identifying the second crystal grains using SEM-EDS, measuring the total area of ​​the second crystal grains from the SEM image, and dividing it by the field of view area. Figure 8 shows an example of a 20 μm × 20 μm region located in the center of the cross-section of a multilayer ceramic capacitor 100 polished in the BB direction in Figure 1.

[0049] Similarly, if the elemental ratio of barium to titanium is too high in the cross-section, a large amount of second crystal grains 40 may be present inside the dielectric layer 11. In this case, the dielectric constant of the dielectric layer 11 may decrease. Therefore, it is preferable to set an upper limit on the elemental ratio of barium to titanium in the cross-section. In this embodiment, in the cross-section including the break in the internal electrode layer 12 and the dielectric layer 11, the elemental ratio of barium to titanium is preferably 0.995 or less, more preferably 0.990 or less, and even more preferably 0.980 or less. The elemental ratio of barium to titanium can be measured by SEM-EDS analysis as described above.

[0050] On the other hand, if the area ratio of the second crystal grains 40 in the cross-section is too small, there is a risk that the number of interruptions in the internal electrode layer 12 will increase, especially when many interruptions occur, resulting in a large number of interruptions where the second crystal grains 40 are not present. Therefore, it is preferable to set a lower limit on the area ratio of the second crystal grains 40 in the cross-section. In this embodiment, it is preferable that the area ratio occupied by the second crystal grains in a 20 μm × 20 μm region located in the center of the cross-section of the multilayer ceramic capacitor 100 polished in the BB direction of Figure 1 is 0.001% or more, more preferably 0.1% or more, and even more preferably 10% or more.

[0051] Similarly, in the cross-section, if the elemental ratio of barium to titanium is too low, there is a risk that the number of interruptions in the internal electrode layer 12 will increase, especially when many interruptions occur, resulting in a large number of interruptions where the second crystal grains 40 are not present. Therefore, it is preferable to set a lower limit on the elemental ratio of barium to titanium in the cross-section. In this embodiment, in the cross-section including the interruptions in the internal electrode layer 12 and the dielectric layer 11, the elemental ratio of barium to titanium is preferably 0.909 or higher, more preferably 0.926 or higher, and even more preferably 0.962 or higher.

[0052] In addition, within the 20 μm × 20 μm region described above, there may be, for example, 1 to 20 interruptions in the internal electrode layer 12, and the second crystal grains 40 may be arranged in 5.0% to 90% of these interruptions.

[0053] Next, the manufacturing method of the multilayer ceramic capacitor 100 will be described. Figure 9 is a diagram illustrating the flow of the manufacturing method of the multilayer ceramic capacitor 100.

[0054] (Process for producing raw material powder) First, a dielectric ceramic composition for forming the dielectric layer 11 is prepared. The A-site and B-site elements contained in the dielectric layer 11 are usually present in the form of a sintered body of ABO3 particles. For example, barium titanate is a compound that has a perovskite structure and belongs to the tetragonal crystal system at around room temperature, exhibiting a high dielectric constant. Barium titanate can generally be synthesized by reacting a titanium raw material such as titanium dioxide with a barium raw material such as barium carbonate and a calcium raw material such as calcium carbonate. Various methods have been conventionally known for synthesizing barium titanate, which is the main component of the dielectric layer 11, such as the solid-phase method, the sol-gel method, and the hydrothermal method. In this embodiment, any of these methods can be employed.

[0055] Titanium is added to the obtained barium titanate powder. For example, titanium oxide (TiO2) can be added. In this embodiment, it is preferable to add titanium to the barium titanate powder such that the elemental ratio of barium to titanium is 0.900 or more and 0.995 or less. For example, 0.5 mol or more and 10 mol or less of titanium is added to 100 mol of barium titanate powder.

[0056] The obtained ceramic powder is then mixed with predetermined additives. As an example, oxides or glasses containing Zr (zirconium), V (vanadium), Cr (chromium), Co (cobalt), Ni (nickel), Li (lithium), B (boron), Na (sodium), and K (potassium) may be used. Additionally, if necessary, oxides of rare earth elements such as Gd (gadolinium), Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Y (ytterbium), and Lu (lutetium) may be added.

[0057] For example, a ceramic material can be prepared by wet-mixing a ceramic raw material powder with a compound containing an additive, followed by drying and pulverization. For example, the ceramic material obtained as described above may be subjected to pulverization as needed to adjust the particle size, or the particle size may be adjusted by combining this with a classification process. A dielectric material can be obtained through the above steps.

[0058] (Coating process) Next, a binder such as polyvinyl butyral (PVB) resin, an organic solvent such as ethanol or toluene, and a plasticizer are added to the obtained dielectric ceramic composition and wet-mixed. Using the resulting slurry, a ceramic green sheet 51 is coated onto a substrate by, for example, a die coater or doctor blade method and then dried. The substrate is, for example, polyethylene terephthalate (PET) film. A diagram illustrating the coating process has been omitted.

[0059] (Internal electrode formation process) Next, as illustrated in Figure 10(a), a metal conductive paste for forming internal electrodes containing an organic binder is printed on the surface of the ceramic green sheet 51 by screen printing, gravure printing, or the like, thereby arranging an internal electrode pattern 52 that is alternately drawn out to a pair of external electrodes with different polarities. Ceramic particles are added to the metal conductive paste as a co-material. The main component of the ceramic particles is not particularly limited, but it is preferable that it is the same as the main component ceramic of the dielectric layer 11. For example, barium calcium titanate with an average particle diameter of 50 nm or less may be uniformly dispersed.

[0060] Next, a binder such as ethylcellulose and an organic solvent such as terpineol are added to the dielectric ceramic composition obtained in the raw material powder preparation process, and the mixture is kneaded in a roll mill to obtain a dielectric pattern paste for the reverse pattern layer. As illustrated in Figure 10(a), the dielectric pattern 53 may be arranged on the ceramic green sheet 51 by printing the dielectric pattern paste in the peripheral area where the internal electrode pattern 52 is not printed, thereby filling the step between it and the internal electrode pattern 52. The ceramic green sheet 51 on which the internal electrode pattern 52 and the dielectric pattern 53 are printed is called a laminate unit.

[0061] Subsequently, as illustrated in Figure 10(b), stacking units are carried out so that the internal electrode layer 12 and the dielectric layer 11 are staggered, and the edges of the internal electrode layer 12 are alternately exposed on both ends of the dielectric layer 11 in the longitudinal direction, alternately leading to a pair of external electrodes 20a and 20b with different polarities. For example, the number of stacked internal electrode patterns 52 is set to 100 to 1000 layers.

[0062] (Crimping process) As illustrated in Figure 11, a predetermined number of cover sheets 54 (for example, 2 to 10 layers) are laminated on the top and bottom of a laminate made up of stacked units and then heat-pressed. After that, they are cut to predetermined chip dimensions (for example, 1.0 mm x 0.5 mm).

[0063] (Firing process) The ceramic laminate thus obtained is subjected to a binder removal treatment in an N2 atmosphere, an air atmosphere, etc., and then a metal paste that will serve as the base layer for the external electrodes 20a and 20b is applied by the dip method, with an oxygen partial pressure of 10 -12 ~10 -9 The multilayer ceramic capacitor 100 is fired in an ATM reducing atmosphere at 1100°C to 1300°C for 10 minutes to 2 hours, and then rapidly cooled. In this way, the multilayer ceramic capacitor 100 is obtained. The heating rate during the firing process is, for example, a rapid heating rate of 6000°C / h. This shortens the actual firing time and makes it possible to achieve higher mass production efficiency.

[0064] (Annealing process) Subsequently, oxygen partial pressure 10 -12 ~10 -9 Anneal at 1000-1150°C for 1-2 hours in a reducing atmosphere (atm), then slowly cool. For example, heat and cool at 400°C / h.

[0065] (Re-oxidation process) Subsequently, a re-oxidation treatment may be performed in an N2 gas atmosphere at 600°C to 1000°C.

[0066] (Plating process) Subsequently, a metal coating of Cu, Ni, Sn, etc. is applied to the underlayer of the external electrodes 20a and 20b by plating. Through these steps, the multilayer ceramic capacitor 100 is completed.

[0067] According to the manufacturing method of this embodiment, barium titanate can be sintered in the firing process. Because titanium is added to the barium titanate, in the annealing process after the firing process, the constituent components that can make up the second crystal particles 40 appear as a liquid phase and are ejected from the dielectric layer 11. In the internal electrode layer 12, discontinuities are created where the metal components have become spheroidal in the firing process. The liquid phase ejected from the dielectric layer 11 moves to the discontinuities in the internal electrode layer 12 and becomes the second crystal particles 40 after cooling. As described above, the second crystal particles 40 can be placed in the discontinuities of the internal electrode layer 12.

[0068] In the embodiments described above, multilayer ceramic capacitors were explained as an example of multilayer ceramic electronic components, but the invention is not limited to them. For example, other multilayer ceramic electronic components such as varistors and thermistors may be used. [Examples]

[0069] (Example 1) 4.0 mol of titanium was added to 100 mol of barium titanate powder, resulting in a Ba / Ti elemental ratio (elemental ratio of barium to titanium) of 0.960 for the ceramic powder. This ceramic powder was mixed with ethanol, toluene, and PVB (polyvinyl butyral) resin to prepare a dielectric slurry. This slurry was molded into a ceramic green sheet using a die coater. After drying the ceramic green sheet, nickel paste was printed to form the internal electrode pattern. The resulting laminated units were stacked and pressed together with thick layers of ceramic green sheets without internal electrode patterns on the top and bottom, and then cut into small pieces. Subsequently, Ni paste was dipped into two end faces as a conductive paste for the external electrodes, and degreasing was performed in nitrogen gas. The degreasing pieces were then subjected to an oxygen partial pressure of 9.6 × 10⁻⁶. -9 The temperature was set to atm, the heating rate to 6000°C / h, and the sample was fired at 1220°C for 1 minute, followed by rapid cooling. Afterward, the oxygen partial pressure was set to 6.0 × 10⁻⁶. -9 The samples were annealed at 1100°C for 2 hours in a reducing atmosphere (atm), followed by slow cooling. The heating rate during annealing was 400°C / h, and the cooling rate was also 400°C / h. Subsequently, the oxygen partial pressure was reduced to 1.0 × 10⁻⁶. -2 The material was treated with atm and re-oxidized at 950°C.

[0070] (Comparative Example 1) In the comparative example, the annealing process was not performed. All other conditions were the same as in Example 1.

[0071] (Presence or absence of the second crystal particle) For each sample in Example 1 and the Comparative Example, it was confirmed whether or not a second crystal particle (Ba4Ti) with an elemental ratio of barium to titanium of 0.70 or less was placed at the break in the internal electrode layer. The results are shown in Table 1. In Example 1, a second crystal particle (Ba4Ti) was placed at the break in the internal electrode layer. 11 O 26 It was confirmed that the second crystal grain was present in the internal electrode layer. This is thought to be because the annealing process was performed. In contrast, in the comparative example, it was confirmed that the second crystal grain was not present in the interrupted portion of the internal electrode layer. This is thought to be because the annealing process was not performed. [Table 1]

[0072] (Moisture resistance test) For each sample in Example 1 and the Comparative Example, the samples were held at 40°C and 90% relative humidity for 500 hours, then left at room temperature for 24 hours, and their insulation resistance was evaluated thereafter. Samples with an insulation resistance of 10 MΩ or higher were judged as pass ("○"), and those with an insulation resistance of less than 10 MΩ were judged as fail ("×"). The results are shown in Table 1. As shown in Table 1, Example 1 passed the humidity resistance test ("○"). This is thought to be because the second crystalline particles with insulating properties were placed in the gaps in the internal electrode layer. In contrast, the Comparative Example failed the humidity resistance test ("×"). This is thought to be because the second crystalline particles were not placed in the gaps in the internal electrode layer.

[0073] (Comparative Example 2) 0.2 mol of titanium was added to 100 mol of barium titanate, resulting in a Ba / Ti elemental ratio of 1.000 in the ceramic powder. All other conditions were the same as in Example 1.

[0074] (Example 2) 0.5 mol of titanium was added to 100 mol of barium titanate, resulting in a Ba / Ti elemental ratio of 0.995 in the ceramic powder. All other conditions were the same as in Example 1.

[0075] (Example 3) 1.0 mol of titanium was added to 100 mol of barium titanate, resulting in a Ba / Ti elemental ratio of 0.990 in the ceramic powder. All other conditions were the same as in Example 1.

[0076] (Example 4) 2.0 mol of titanium was added to 100 mol of barium titanate, resulting in a Ba / Ti elemental ratio of 0.980 in the ceramic powder. All other conditions were the same as in Example 1.

[0077] (Example 5) 4.0 mol of titanium was added to 100 mol of barium titanate, resulting in a Ba / Ti elemental ratio of 0.970 in the ceramic powder. All other conditions were the same as in Example 1.

[0078] (Example 6) 8.0 mol of titanium was added to 100 mol of barium titanate, resulting in a Ba / Ti elemental ratio of 0.920 in the ceramic powder. All other conditions were the same as in Example 1.

[0079] (Example 7) 10 moles of titanium were added to 100 moles of barium titanate, resulting in a Ba / Ti elemental ratio of 0.909 in the ceramic powder. All other conditions were the same as in Example 1.

[0080] (Presence or absence of the second crystal particle) For each sample in Examples 2-7 and Comparative Example 2, it was confirmed whether or not a second crystalline particle (Ba4Ti) with an elemental ratio of barium to titanium of 0.70 or less was placed at the break in the internal electrode layer. The results are shown in Table 2. In Examples 2-7, a second crystalline particle (Ba4Ti) was placed at the break in the internal electrode layer. 11 O 26 It was confirmed that the following was present. This is thought to be because the amount of titanium added to 100 mol of barium titanate was sufficient and the annealing process was carried out. In Comparative Example 2, it is thought that the amount of titanium added was insufficient because the Ba / Ti ratio was set to 1.000. [Table 2]

[0081] (Moisture resistance test) For each sample in Examples 2-7 and Comparative Example 2, the samples were held at 40°C and 90% relative humidity for 500 hours, then left at room temperature for 24 hours, after which the insulation resistance was evaluated. Samples with an insulation resistance of 10 MΩ or higher were judged as pass ("○"), and those with an insulation resistance of less than 10 MΩ were judged as fail ("×"). The results are shown in Table 2. As shown in Table 2, Examples 2-7 passed the humidity resistance test ("○"). This is thought to be because the second crystal particles were placed in the interrupted portions of the internal electrode layer. In contrast, Comparative Example 2 failed the humidity resistance test ("×"). This is thought to be because the second crystal particles were not placed in the interrupted portions of the internal electrode layer.

[0082] (Dielectric constant test) Capacitance was measured using an LCR meter under the conditions of temperature: 25°C, measurement voltage: 1.0V, and measurement frequency: 1kHz. The relative permittivity was calculated from the dielectric thickness and electrode area. The results are shown in Table 2. As shown in Table 2, it was confirmed that the relative permittivity tends to decrease as the Ba / Ti ratio decreases. This is thought to be because, as the Ba / Ti ratio decreases, more second crystal grains with an elemental ratio of barium to titanium of 0.70 or less are generated inside the dielectric layer. From these results, it can be seen that a Ba / Ti ratio of 0.909 to 0.995 is preferable.

[0083] Although embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0084] 10 Base Body 11 Dielectric layer 12 Internal electrode layer 13. Cover layer 14 capacity area 15 End margin 16 Side margins 20a,20b external electrode 30 First crystal grain 40 Second crystal grain 51 Ceramic Green Sheet 52 Internal electrode patterns 53 Dielectric Pattern 54 Cover Sheets 55 Side margin section 100 Multilayer Ceramic Capacitors

Claims

1. The laminate comprises multiple dielectric layers and multiple internal electrode layers stacked alternately, The plurality of dielectric layers are governed by the general formula ABO ３ The main phase consists of first crystalline grains made of barium titanate having a perovskite structure represented by , A multilayer ceramic electronic component in which at least one of the plurality of internal electrode layers has a discontinuity, and a second crystal particle having an elemental ratio of barium to titanium of 0.70 or less is disposed in the discontinuity.

2. The second crystal particles are BaTi ２ O ５ 、BaTi ４ O ９ 、BaTi ５ O １１ 、BaTi ６ O １３ 、Ba ４ Ti １１ O ２６ 、Ba ４ Ti １２ O ２７ 、Ba ４ Ti １３ O ３０ 、or Ba ６ Ti １７ O ４０ The multilayer ceramic electronic component according to claim 1, which is at least one selected from these.

3. The multilayer ceramic electronic component according to claim 1, wherein in a 20 μm × 20 μm region located in the center of a cross-section including the stacking direction of the plurality of dielectric layers and the plurality of internal electrode layers, the proportion of the area occupied by the second crystal grain is 0.001% or more and 50% or less.

4. The multilayer ceramic electronic component according to claim 1, wherein the elemental ratio of barium to titanium in the plurality of dielectric layers is 0.909 or more and 0.995 or less.

5. The multilayer ceramic electronic component according to claim 1, wherein the second crystal grains are arranged across the entire width of the interrupted portion.

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