Electronic component

Abstract

To provide an electronic component that can suppress the occurrence of cracks in a high-temperature, high-humidity environment.SOLUTION: In an electronic component having an element body in which ceramic layers and internal electrode layers are laminated, the ceramic layers contain a perovskite-type compound whose main component is represented by the general formula ABO3, and the perovskite-type compound is a compound that can be represented by the composition formula (Ca1-xSrx)m(Zr1-y-zTiyHfz)O3, and m is in the range of 0.9 to 1.1, x satisfies 0≤x≤1, and y and z satisfy 0.80≤1-y-z≤1.0, and the element body has segregation, and the segregation includes Ca and / or Sr, Mn, Si, Ni, and O.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electronic component having ceramic layers and internal electrode layers. [Background technology]

[0002] Multilayer ceramic electronic components are known in which ceramic layers made of a dielectric composition and internal electrode layers are alternately stacked. In these multilayer ceramic electronic components, there are differences in properties, such as shrinkage rate and linear expansion coefficient, between the ceramic layers and the internal electrode layers. As a result, structural defects such as cracks are likely to occur at the interfaces between the ceramic layers and the internal electrode layers due to these differences in properties, and this tendency is particularly pronounced in high-temperature, high-humidity environments.

[0003] In response to this, for example, Patent Document 1 discloses a method of reducing the number of cracks that occur after firing by forming a secondary phase material at the interface between the internal electrode and the dielectric layer, but no research has been conducted on this method in a high-temperature, high-humidity environment. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-123698 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and has an object to provide an electronic component that can suppress the occurrence of cracks in a high-temperature, high-humidity environment. [Means for solving the problem]

[0006] In order to achieve the above object, an electronic component according to the present invention comprises: An electronic component having an element body in which ceramic layers and internal electrode layers are laminated, the ceramic layer contains a perovskite-type compound represented by the general formula ABO3 as a main component, The perovskite compound has the composition formula (Ca 1-x Sr x ) m (Zr 1-y-z Ti y Hf z )O3, The m is in the range of 0.9 to 1.1, wherein x satisfies 0≦x≦1; the y and the z satisfy 0.80≦1−yz≦1.0, the element body has segregation, The segregation includes Ca and / or Sr, Mn, Si, Ni, and O.

[0007] Since the electronic component of the present invention has a predetermined segregation in the element body, it is possible to suppress the occurrence of cracks in a high-temperature and high-humidity environment.

[0008] The segregation may include Al.

[0009] Preferably, the segregation exists at an electrode discontinuity portion of the internal electrode layer. Also, preferably, the segregation exists so as to contact the lamination interface between the ceramic layer and the internal electrode layer. That is, preferably, the element body has the segregation existing at the electrode discontinuity portion of the internal electrode layer and / or the segregation existing so as to contact the lamination interface between the ceramic layer and the internal electrode layer.

[0010] This makes it possible to further suppress the occurrence of cracks in a high-temperature and high-humidity environment.

[0011] Preferably, the ratio of the total atomic weight of Ca and Sr to the total atomic weight of Zr and Ti in the segregation {(Ca+Sr) / (Zr+Ti)} is 1.5 to 8.0.

[0012] This makes it possible to further suppress the occurrence of cracks in a high-temperature and high-humidity environment.

[0013] When the total amount of Hf, Ni, Mn, Ti, Si, Al, Ca, Zr and Sr in the segregation calculated as oxides is 100 parts by mole, Preferably, the total content of Ca and Sr in the segregation is 25 parts by mol or more and less than 60 parts by mol in terms of oxides.

[0014] Preferably, the ratio of the atomic weight of Mn to the total atomic weight of Mn and Si in the segregation {Mn / (Mn+Si)} is 0.02 or more and less than 0.50.

[0015] This makes it possible to further suppress the occurrence of cracks in a high-temperature and high-humidity environment.

[0016] Preferably, the ratio of the atomic weight of Ni to the total atomic weight of Ni and Si in the segregation {Ni / (Ni+Si)} is 0.02 or more and less than 0.6.

[0017] This makes it possible to further suppress the occurrence of cracks in a high-temperature and high-humidity environment.

[0018] Preferably, the average number of the segregations per unit length of the internal electrode layers is 0.05 pieces / μm or more and less than 0.5 pieces / μm.

[0019] This makes it possible to further suppress the occurrence of cracks in a high-temperature and high-humidity environment.

[0020] Preferably, the average particle size of the segregation is 0.1 μm to 15 μm.

[0021] This makes it possible to further suppress the occurrence of cracks in a high-temperature and high-humidity environment.

[0022] Preferably, the main component of the conductive material contained in the internal electrode layers is Ni and / or a Ni-based alloy.

[0023] This makes it possible to further suppress the occurrence of cracks in a high-temperature and high-humidity environment.

[0024] Preferably, the main components of the ceramic layer include Ca, Sr, Zr and Ti.

[0025] This makes it possible to further suppress the occurrence of cracks in a high-temperature and high-humidity environment. [Brief explanation of the drawings]

[0026] [Figure 1A] FIG. 1A is a cross-sectional view showing a multilayer ceramic capacitor according to one embodiment of the present invention. [Figure 1B] FIG. 1B is a cross-sectional view of the multilayer ceramic capacitor taken along line IB-IB in FIG. 1A. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a main part of FIG. 1A. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention will be described in detail below based on the embodiments shown in the drawings.

[0028] First embodiment 1A and 1B will be described as an example of an electronic component according to the present invention. The multilayer ceramic capacitor 2 has an element body 4 and a pair of external electrodes 6 formed on the outer surface of the element body 4.

[0029] 1A and 1B is generally shaped like a rectangular parallelepiped. However, the shape of the element body 4 is not particularly limited and may be an elliptical cylinder, a circular cylinder, a rectangular column, or the like. The outer dimensions of the element body 4 are also not particularly limited and may be, for example, a length L0 in the X-axis direction of 0.4 mm to 5.7 mm, a width W0 in the Y-axis direction of 0.2 mm to 5.0 mm, and a height T0 in the Z-axis direction of 0.2 mm to 3.0 mm.

[0030] In this embodiment, the X-axis, Y-axis, and Z-axis are perpendicular to each other.

[0031] The element body 4 has ceramic layers 10 (dielectric layers 10) and internal electrode layers 12 that are substantially parallel to a plane including the X-axis and Y-axis, and inside the element body 4, the ceramic layers 10 and the internal electrode layers 12 are alternately stacked along the Z-axis direction. Here, "substantially parallel" means that most of the portions are parallel, but there may be some portions that are not parallel, and the ceramic layers 10 and the internal electrode layers 12 may have some irregularities or may be tilted.

[0032] The ceramic layer 10 preferably contains Ca and / or Sr and Zr as its main components, and more preferably contains a perovskite-type compound represented by the general formula ABO3. Here, the main component of the ceramic layer 10 refers to a component in which the total of the elements constituting the main component of the ceramic layer 10 is 80 molar parts or more when the total of the elements constituting the ceramic layer 10 is 100 molar parts. In this embodiment, the perovskite-type compound preferably contains at least Ca and Sr in the A site, and is represented by the composition formula (Ca 1-x Sr x ) m (Zr 1-y-z Ti y Hf z )O3 (hereinafter referred to as a CSZT-based compound). In the above composition formula, the symbols x, y, z, and m each represent an element ratio, and the element ratio is not particularly limited and can be set within a known range.

[0033] For example, m indicates the element ratio of the A site to the B site, and can generally be in the range of 0.9 to 1.1. Also, x indicates the element ratio of Sr occupying the A site, and can be 0≦x≦1. In other words, the ratio of Ca to Sr is arbitrary, and only one of them may be contained.

[0034] y represents the element ratio of Ti in the B site, and z represents the element ratio of Hf in the B site. That is, 1-yz represents the element ratio of Zr in the B site. In this embodiment, it is preferable that 0.80≦1-yz≦1.0. When the element ratio of Zr is within the above range, the high-temperature loaded life under high voltage is improved, and the crack occurrence rate can be further suppressed.

[0035] The element ratio of oxygen (O) in the above composition formula may deviate slightly from the stoichiometric composition.

[0036] In addition to the above-described main components, the ceramic layer 10 may contain auxiliary components, such as Mn compounds, Si compounds, Al compounds, Mg compounds, Ni compounds, Li compounds, and B compounds, and the types, combinations, and amounts of the auxiliary components are not particularly limited.

[0037] The ceramic layer 10 includes main phase grains formed of an oxide having a perovskite crystal structure made of a CSZT-based compound, and grain boundaries. The grain boundaries may also include segregations 14 having a different composition from the main phase grains. The above-described minor components of the ceramic layer 10 may be contained in the main phase grains as a solid solution, in the grain boundaries, or as segregations 14.

[0038] The average thickness Td (interlayer thickness) per ceramic layer 10 is not particularly limited and can be, for example, 40 μm or less, preferably 20 μm or less. The number of stacked ceramic layers 10 can be determined depending on the desired properties and is not particularly limited. For example, it can be 20 layers or more, more preferably 50 layers or more.

[0039] On the other hand, the internal electrode layers 12 are laminated between the ceramic layers 10, and the number of laminated layers is determined according to the number of laminated ceramic layers 10. The average thickness Te of each internal electrode layer 12 is not particularly limited, and is preferably, for example, 3.0 μm or less.

[0040] Furthermore, the multiple internal electrode layers 12 are stacked so that one end is alternately exposed on two end faces opposing each other in the X-axis direction of the element body 4. A pair of external electrodes 6 is formed on one end face of the element body 4, and is electrically connected to the exposed ends of the alternately arranged internal electrode layers 12. By forming the internal electrode layers 12 and external electrodes 6 in this manner, the external electrodes 6 and internal electrode layers 12 form a capacitor circuit.

[0041] 1A and 1B, the internal electrode layers 12 are present not only in the X-axis direction but also along the Y-axis direction. Therefore, even if the internal electrode layers 12 appear to be interrupted along the X-axis in a cross-sectional view parallel to the ZX plane of the multilayer ceramic capacitor 2, they are actually electrically continuous via the internal electrode layers 12 present in the Y-axis direction. In the following, such a portion where the internal electrode layers 12 appear to be interrupted in a cross-section parallel to the lamination direction is referred to as an electrode interruption portion 12a.

[0042] The presence rate of the electrode discontinuities 12a can be determined from the internal electrode layer coverage. The internal electrode layer coverage is the ratio of the total length of the internal electrode layers 12 along the lamination interface 11 to the total length of the ceramic layers 10 along the lamination interface 11 when observing a pair of ceramic layers 10 and internal electrode layers 12 that contact each other in a predetermined field of view in a cross section (YZ plane or ZX plane) parallel to the lamination direction (Z-axis direction) of the element body 4. The length in the lamination direction of the predetermined field of view may be a length that allows a pair of ceramic layers 10 and internal electrode layers 12 that contact each other to be grasped. The length in the direction parallel to the lamination direction of the predetermined field of view may be approximately 10 μm to 500 μm. It is preferable to observe approximately five fields of view that fill the predetermined field of view and calculate the average value of the internal electrode layer coverage.

[0043] In this embodiment, the coverage of the internal electrode layers is preferably 85% or more and 99% or less. As will be described later, it is preferable that the segregations 14 exist in the electrode discontinuities 12a, and therefore it is preferable that the electrode discontinuities 12a exist to a moderate extent while the internal electrode layers 12 function. For this reason, the coverage of the internal electrode layers is preferably in the above range, and more preferably 90% or more and 98% or less.

[0044] Furthermore, the average number of electrode interruptions 12a per unit length at the lamination interface 11 is preferably 0.01 or more / μm and 1.5 or less / μm. As will be described later, it is preferable that segregations 14 exist in the electrode interruptions 12a, and therefore it is preferable that the electrode interruptions 12a exist at an appropriate frequency while still functioning as internal electrode layers 12. For this reason, the average number of electrode interruptions 12a per unit length at the lamination interface 11 is preferably within the above range, and more preferably 0.04 or more / μm and 1.5 or less / μm.

[0045] The number of electrode interruptions 12 a per unit length of the lamination interface 11 can be examined within the above-mentioned predetermined field of view for calculating the internal electrode layer coverage rate, and it is preferable to observe approximately five fields of view that satisfy the predetermined field of view and calculate the average number of electrode interruptions 12 a per unit length of the lamination interface 11.

[0046] As described above, the internal electrode layers 12 function as part of the capacitor circuit to apply a voltage to each ceramic layer 10. Therefore, the material of the internal electrode layers 12 contains a conductive material. Specific examples of the material that can be used include Cu, Ni, Ag, Pd, Au, Pt, or an alloy containing at least one of these metal elements. When the constituent material of the ceramic layers 10 is resistant to reduction, the main component of the conductive material contained in the internal electrode layers 12 is preferably Ni and / or a Ni-based alloy. The Ni contained in the internal electrode layers 12 and the Mn contained in the segregations 14 are alloyed to improve the bonding strength at the lamination interface 11. Here, the "Ni-based alloy" is preferably an alloy of Ni and Sn (Ni-Sn-based alloy) with Ni as the main component. In addition, "the main component of the conductive material contained in the internal electrode layer 12" refers to a component in which the total of the elements constituting the main component of the conductive material contained in the internal electrode layer 12 is 80 parts by mole or more when the total of the elements constituting the conductive material contained in the internal electrode layer 12 is 100 parts by mole. Furthermore, when Ni or a Ni-based alloy is the main component, one or more types of sub-components for the internal electrode selected from Mn, Cu, Cr, etc. may be contained.

[0047] Furthermore, in addition to the above-mentioned conductive material, the internal electrode layers 12 may contain the ceramic components contained in the ceramic layers 10 as co-materials (for example, CSZT-based compounds), and may also contain trace amounts (for example, about 0.1 mass % or less) of non-metallic components such as S and P. The co-materials have the effect of suppressing sintering of the conductive material during the firing process.

[0048] There are no particular restrictions on the conductive material contained in the external electrodes 6. For example, known conductive materials such as Ni, Cu, Sn, Ag, Pd, Pt, Au, or alloys of these, conductive resins, etc. may be used. The thickness of the external electrodes 6 may be determined appropriately depending on the application, etc., but is usually preferably about 1.0 μm to 150 μm.

[0049] 2 is a schematic cross-sectional view of the element body 4. In this embodiment, the element body 4 has segregations 14. That is, the segregations 14 are contained in and present in the ceramic layers 10 and / or the internal electrode layers 12. In particular, the segregations 14 are preferably present in the electrode discontinuities 12a. Furthermore, the segregations 14 are preferably present so as to contact the lamination interface 11, which is the interface between the ceramic layers 10 and the internal electrode layers 12. Furthermore, the segregations 14 are preferably present in the electrode discontinuities 12a and so as to contact the lamination interface 11.

[0050] The segregation 14 contains Ca and / or Sr, Mn, Si, Ni, and O. The segregation 14 may also contain Al. Hereinafter, Si and / or Al are collectively referred to as "M." The segregation 14 has higher concentrations of Ca and / or Sr, Mn, and M than the ceramic layer 10 or the internal electrode layer 12. The segregation 14 also has a higher concentration of Ni than the ceramic layer 10.

[0051] The ratio of the total atomic weight of Ca and Sr to the total atomic weight of Zr and Ti in the segregation 14 {(Ca+Sr) / (Zr+Ti)} is preferably 1.5 to 8.0, and more preferably 2.5 to 6.5.

[0052] When the total amount of Hf, Ni, Mn, Ti, Si, Al, Ca, Zr, and Sr in the segregation 14 calculated as oxides is taken as 100 parts by mol, the total content ratio of Ca and Sr in the segregation 14 calculated as oxides is preferably 25 parts by mol or more and less than 60 parts by mol.

[0053] Here, the term "Hf oxide equivalent" means HfO2 equivalent.

[0054] Ni oxide equivalent means NiO equivalent.

[0055] Mn in oxide equivalent means MnO equivalent.

[0056] The term "Ti oxide equivalent" means TiO2 equivalent.

[0057] The term "Si oxide equivalent" means SiO2 equivalent.

[0058] The term "Al oxide equivalent" means Al2O3 equivalent.

[0059] The term "Ca in oxide equivalent" means CaO equivalent.

[0060] Zr oxide equivalent means ZrO2 equivalent.

[0061] The term "Sr in terms of oxide" means SrO.

[0062] The ratio of the atomic weight of Mn to the total atomic weight of Mn and Si in the segregation 14 {Mn / (Mn+Si)} is preferably 0.02 or more and less than 0.50, and more preferably 0.08 or more and 0.30 or less.

[0063] The ratio of the atomic weight of Ni to the total atomic weight of Ni and Si in the segregation 14 {Ni / (Ni+Si)} is preferably 0.02 or more and less than 0.6, or 0.10 or more and 0.40 or less.

[0064] The average number of segregations 14 per unit length of the internal electrode layer 12 is preferably 0.05 / μm or more and less than 0.5 / μm, more preferably 0.1 / μm or more and 0.3 / μm or less. The length of the internal electrode layer 12 is the length along the direction (X-axis direction or Y-axis direction) perpendicular to the stacking direction (Z-axis direction). Therefore, the length of the internal electrode layer 12 is measured from the YZ cross section or ZX cross section of the element body 4, but an electrode interruption 12a exists in the YZ cross section or ZX cross section of the element body 4. In this case, the electrode interruption 12a is not included in the length of the internal electrode layer 12. Furthermore, the segregations 14 counted as the number of segregations 14 per unit length of the internal electrode layer 12 are "segregations 14 existing in the electrode interruption 12a of the internal electrode layer 12" and / or "segregations 14 existing so as to contact the stacking interface 11 between the ceramic layer 10 and the internal electrode layer 12."

[0065] The average particle size of the segregation 14 is preferably 0.1 μm to 15 μm, more preferably 0.5 μm to 10 μm, and even more preferably 1.0 μm to 5 μm. In this embodiment, the "average particle size" means the arithmetic mean value of the equivalent circle diameter.

[0066] The element body 4 can be analyzed by cross-sectional observation using a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM).

[0067] For example, the presence or absence of segregation 14 can be measured by image analysis of a cross-sectional photograph obtained by cross-sectional observation using an SEM, STEM, or the like. When a cross-section of the element body 4 is observed using an SEM backscattered electron image or an STEM HAADF image, high-density areas can often be recognized as areas with bright contrast. Here, in the element body 4, the internal electrode layer 12 tends to have the highest density, the ceramic layer 10 has the next highest density, and the segregation 14 has the lowest density. For this reason, the internal electrode layer 12 can often be recognized as an area with bright contrast, and the segregation 14 can often be recognized as an area with dark contrast. Furthermore, the ceramic layer 10 can often be recognized as an area with darker contrast than the internal electrode layer 12 and brighter contrast than the segregation 14.

[0068] From the above, the presence, location, size and number of segregations 14 in the element body 4 can be determined from the contrast brightness obtained by binarizing a cross-sectional photograph parallel to the stacking direction of the element body 4.

[0069] The particle size of the segregation 14 is the circle-equivalent diameter of the segregation 14. Therefore, the area of ​​the segregation 14 is calculated, and the circle-equivalent diameter is calculated, and the circle-equivalent diameter can be set as the particle size of the segregation 14.

[0070] It is preferable to observe the cross section of the element body 4 in five fields of view of about 25 μm×25 μm, measure the particle size and number of segregations 14, and calculate the average value.

[0071] The composition of the segregation 14 can be measured by performing a component analysis using an electron probe microanalyzer (EPMA) when observing the cross section. It is preferable to perform the component analysis at at least three locations and calculate the composition of the segregation 14 from the average value of the measurement results. In this embodiment, when performing the component analysis using the EPMA, an energy dispersive spectrometer (EDS) or a wavelength dispersive spectrometer (WDS) can be used as the X-ray spectrometer.

[0072] Next, an example of a method for manufacturing the multilayer ceramic capacitor 2 shown in FIGS. 1A and 1B will be described.

[0073] First, we will explain the manufacturing process of the element body 4. In the manufacturing process of the element body 4, a dielectric paste that will become the ceramic layers 10 after firing and a segregation-containing internal electrode paste that will become the internal electrode layers 12 after firing are prepared.

[0074] The dielectric paste is manufactured, for example, by the following method. First, the dielectric raw materials are uniformly mixed by means such as wet mixing and dried. Then, a calcined powder is obtained by heat treatment under specified conditions. Next, a known organic vehicle or a known aqueous vehicle is added to the calcined powder and kneaded to prepare a dielectric paste. The dielectric paste thus obtained is formed into a sheet by a method such as a doctor blade method to obtain a ceramic green sheet. The dielectric paste may contain additives selected from various dispersants, plasticizers, dielectrics, auxiliary component compounds, glass frit, etc., as necessary.

[0075] The paste for the segregation-containing internal electrode is prepared by kneading a metal material with a known binder and solvent. Here, the metal material is obtained by mixing and calcining segregation raw materials containing the elements that make up the segregation 14, pulverizing the calcined powder, and mixing it with a conductive material. The segregation raw materials are oxides, carbonates, hydroxides, etc. of the elements that make up the segregation 14.

[0076] By changing the content of the segregation raw material contained in the segregation-containing internal electrode paste, the number of segregations 14 per unit length of the internal electrode layer 12 can be changed.

[0077] Furthermore, when producing a paste for a segregation-containing internal electrode, the particle size of the segregation 14 can be changed by changing the pulverization conditions of the calcined powder of the segregation raw material. Specifically, the particle size of the segregation 14 tends to become smaller when the pulverization time in the ball mill is increased.

[0078] Next, the paste for the segregation-containing internal electrode is applied in a predetermined pattern onto the ceramic green sheets by various printing methods such as screen printing or transfer methods to form a segregation-containing internal electrode pattern. Then, the ceramic green sheets on which the segregation-containing internal electrode pattern has been formed are stacked in multiple layers, and then pressed in the stacking direction to obtain a mother laminate. At this time, the ceramic green sheets and the segregation-containing internal electrode pattern are stacked so that the ceramic green sheets are located on the upper and lower surfaces of the mother laminate in the stacking direction.

[0079] The mother laminate obtained by the above process is cut to a predetermined size by dicing or press-cutting to obtain multiple green chips. If necessary, the green chips may be solidified and dried to remove plasticizers, and after solidification and drying, they may be barrel-polished using a horizontal centrifugal barrel machine or the like. In barrel polishing, the green chips are placed in a barrel container together with media and polishing solution, and the barrel container is subjected to rotational motion or vibration to polish away unnecessary areas such as burrs generated during cutting. After barrel polishing, the green chips are washed with a cleaning solution such as water and dried.

[0080] Next, the green chip obtained above is subjected to a binder removal process and a firing process to obtain the element body 4. The conditions for the binder removal process are not particularly limited and may be appropriately determined depending on the main component composition of the ceramic layers 10 and the main component composition of the internal electrode layers 12. For example, the temperature rise rate is preferably 5°C / hour to 300°C / hour, the holding temperature is preferably 180°C to 400°C, and the temperature holding time is preferably 0.5 hours to 24 hours. The binder removal atmosphere is air or a reducing atmosphere.

[0081] The firing conditions are not particularly limited and may be appropriately determined depending on the main component composition of the ceramic layers 10 and the main component composition of the internal electrode layers 12. For example, the holding temperature during firing is preferably 1200°C to 1400°C, more preferably 1220°C to 1300°C, the holding time is preferably 0.5 hours to 8 hours, more preferably 1 hour to 3 hours, and the heating rate and cooling rate (temperature drop rate) are preferably 50°C / hour to 500°C / hour. The firing atmosphere is preferably a reducing atmosphere, and the atmospheric gas may be, for example, a humidified mixed gas of N2 and H2. Furthermore, when the internal electrode layers 12 are made of a base metal such as Ni or a Ni-based alloy, the oxygen partial pressure in the firing atmosphere should be 2.0 x 10 -13 atm~1.0×10 -7 It is preferable to use atm.

[0082] After firing, the obtained element body 10 may be subjected to a reoxidation treatment (annealing) as necessary. The annealing conditions are preferably, for example, such that the oxygen partial pressure during annealing is higher than the oxygen partial pressure during firing, and the holding temperature is 1150°C or lower.

[0083] In the above-described binder removal treatment, firing treatment, and annealing treatment, a wetter or the like may be used to humidify the N2 gas or mixed gas, and in this case, the water temperature is preferably about 5° C. to 75° C. Furthermore, the binder removal treatment, firing treatment, and annealing treatment may be performed consecutively or independently.

[0084] In the element body 4 obtained as described above, during the process of firing the internal electrode layer 12, the segregation raw material is expelled to the outside of the internal electrode layer 12 and precipitates as segregation 14 on the ceramic layer 10 side of the electrode discontinuity 12a and the lamination interface 11.

[0085] The end faces of the element body 4 obtained as described above are polished, and an external electrode paste is applied and baked to form the external electrodes 6. Then, if necessary, a coating layer is formed on the surface of the external electrodes 6 by plating or the like.

[0086] Through the above steps, the multilayer ceramic capacitor 2 having the external electrodes 6 is obtained.

[0087] The obtained multilayer ceramic capacitor 2 can be surface-mounted on a substrate such as a printed wiring board using solder (including molten solder, solder cream, and solder paste) or a conductive adhesive, and is used in various electronic devices, etc. Alternatively, the multilayer ceramic capacitor 2 can be mounted on a substrate via wire-shaped lead terminals or plate-shaped metal terminals.

[0088] The multilayer ceramic capacitor 2 according to this embodiment has the predetermined segregation 14, which makes it possible to suppress the occurrence of cracks.

[0089] In particular, when the segregation 14 is "segregation 14 present in the electrode interruption 12a" and / or "segregation 14 present so as to be in contact with the lamination interface 11," the bonding strength between the ceramic layer 10 and the internal electrode layer 12 is improved near the electrode interruption 12a and the lamination interface 11. This makes it possible to further suppress the occurrence of cracks originating from the electrode interruption 12a and the lamination interface 11.

[0090] In particular, when the internal electrode layers 12 contain Ni, the Mn contained in the segregations 14 and the Ni contained in the internal electrode layers 12 tend to form an alloy. Therefore, the segregations 14, which are formed on the ceramic layer 10 side of the lamination interface 11 and contain Mn, and the internal electrode layers 12, which contain Ni, alloy each other, thereby increasing the bonding strength. This makes it possible to suppress the occurrence of cracks.

[0091] Furthermore, electronic components in which the ceramic layer 10 is made of a CSZT-based compound tend to be used in high-frequency systems because the temperature change rate of the dielectric constant is lower than that of electronic components in which the ceramic layer 10 is made of barium titanate (hereinafter referred to as a "BT-based compound").

[0092] Thus, while it is preferable to use the ceramic layer 10 composed of a CSZT-based compound in a high-frequency system, the difference in the linear expansion coefficient between a CSZT-based compound and Ni is larger than the difference in the linear expansion coefficient between a BT-based compound and Ni. Therefore, assuming that the main component of the conductive material contained in the internal electrode layer 12 is Ni and / or a Ni-based alloy, when the main component of the ceramic layer 10 is a CSZT-based compound, there is a higher possibility of cracks occurring than when the main component of the ceramic layer 12 is a BT-based compound.

[0093] In contrast to this, in this embodiment, since the segregations 14 also contain Ca, even if the main component of the ceramic layer 10 is a CSZT-based compound, the Ca contained in the ceramic layer 10 and the Ca contained in the segregations 14 interdiffuse, and therefore the bonding strength between the ceramic layer 10 and the internal electrode layer 12 can be further increased via the segregations 14. This makes it possible to further suppress the occurrence of cracks.

[0094] Furthermore, when the main component of the ceramic layer 10 is a CSZT-based compound, the ceramic layer 10 may contain Mn. In particular, Mn may be contained as a solid solution in the main phase grains 10a formed of the CSZT-based compound, and Mn may also be contained in the grain boundaries 10b. In this embodiment, Mn is also contained in the segregations 14, and therefore, the Mn contained in the main phase 10a and / or the grain boundaries 10b of the ceramic layer 10 and the Mn contained in the segregations 14 interdiffuse with each other, thereby further increasing the bonding strength between the ceramic layer 10 and the internal electrode layer 12 via the segregations 14. This makes it possible to further suppress the occurrence of cracks.

[0095] Similarly, when the main component of the ceramic layer 10 is a CSZT-based compound, the ceramic layer 10 may contain M (Si and / or Al). In this embodiment, the segregation 14 also contains M, and therefore the M contained in the ceramic layer 10 and the M contained in the segregation 14 can interdiffuse to further increase the bonding strength between the ceramic layer 10 and the segregation 14. This can further suppress the occurrence of cracks.

[0096] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the present invention.

[0097] For example, in this embodiment, the multilayer ceramic capacitor 2 is exemplified as an electronic component, but the electronic component of the present invention may be, for example, a bandpass filter, a multilayer three-terminal filter, a piezoelectric element, a thermistor, a varistor, or the like.

[0098] In this embodiment, the ceramic layers 10 and the internal electrode layers 12 are stacked in the Z-axis direction, but the stacking direction may be the X-axis direction or the Y-axis direction. In this case, the external electrode 6 may be formed to match the exposed surface of the internal electrode layer 12. The element body 4 does not necessarily have to be a laminate, but may be a single layer. Furthermore, the internal electrode layer 12 may be drawn to the outer surface of the element body 4 via a through-hole electrode, in which case the through-hole electrode and the external electrode 6 are electrically connected. [Example]

[0099] The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

[0100] (Experiment 1) Experiment 1 concerns sample numbers 2 to 11, 21 to 23, 41 to 44, 51 to 54, and 61 to 64.

[0101] In Experiment 1, a multilayer ceramic capacitor 2 was fabricated according to the following procedure. First, a dielectric paste and a segregation-containing internal electrode paste were prepared, and green chips were fabricated using these pastes by the sheet method according to the method described in the embodiment.

[0102] In this case, the dielectric raw materials contained in the dielectric paste were raw materials having the compositions shown in Table 1A, Table 2A, Table 4A, Table 5A or Table 6A. The secondary component compounds contained in the dielectric paste were SiO2, Al2O3 and MnCO3.

[0103] The conductive material of the metal material contained in the segregation-containing internal electrode paste was Ni. The segregation raw material to be contained in the metal material together with Ni had the content of each element adjusted so as to have the composition shown in Table 1B, Table 2B, Table 4B, Table 5B, or Table 6B after firing.

[0104] Next, the green chip obtained above was subjected to a binder removal process under the conditions described in the embodiment, and then a firing process was performed to obtain the element body 4. The firing process conditions were a holding temperature of 1300°C, a holding time of 2 hours, and an atmospheric gas of humidified N2+H2 mixed gas. Then, the element body 4 was subjected to an annealing process under the conditions described in the embodiment.

[0105] The end faces of the element body 10 obtained as described above were polished, and an external electrode paste was applied and baked to form the external electrodes 4.

[0106] In Experiment 1, the dimensions of the element body 4 of the capacitor sample were L0×W0×T0=2.0 mm×1.30 mm×1.30 mm. The number of laminated ceramic layers 10 sandwiched between the internal electrode layers 12 was 80.

[0107] In addition, a sample for destructive testing was extracted from the capacitor sample according to Sample No. 9 of Experiment 1, and a cross-section of the sample was observed using an SEM. Specifically, the extracted sample was cut along the ZX plane, and the cross-section was mirror-polished. Then, the average thickness Td of the ceramic layers 10 and the average thickness Te of the internal electrode layers 12 were measured using secondary electron images from the SEM. The measurement results were as follows:

[0108] Average thickness Td of ceramic layer 10: 2.50 μm Average thickness Te of the internal electrode layer 12: 1.10 μm

[0109] Furthermore, the above cross-sectional observation confirmed the presence or absence of segregation 14, and component analysis of ceramic layer 10, internal electrode layer 12, and segregation 14 was performed by point analysis using EPMA. As a result, it was confirmed that the measurement results for ceramic layer 10 generally matched the composition of the dielectric raw material and subcomponent compounds contained in the dielectric paste. It was also confirmed that internal electrode layer 12 contained Ni, a conductive material contained in the internal electrode paste, as its main component. Furthermore, it was confirmed that the measurement results for segregation 14 generally matched the composition of the segregation raw material contained in the segregation-containing internal electrode paste.

[0110] Therefore, in each of the following experiments, it was estimated that the measurement results of the ceramic layer 10 were consistent with the composition of the dielectric raw material and subcomponent compounds contained in the dielectric paste. It was also estimated that the internal electrode layer 12 contained Ni, a conductive material contained in the internal electrode paste or the segregation-containing internal electrode paste, as its main component. It was also estimated that the measurement results of the segregation 14 were consistent with the composition of the segregation raw material contained in the segregation-containing internal electrode paste.

[0111] The presence or absence of segregation 14 is shown in Table 1B, Table 2B, Table 3B, Table 4B, Table 5B, Table 6B, Table 7B and Table 8B.

[0112] The locations of segregations 14 are shown in Tables 1C, 2B, 3B, 4B, 5B, 6B, 7B and 8B.

[0113] In Tables 4B, 5B, 6B, 7B, and 8B, the ratio of the total atomic weight of Ca and Sr to the total atomic weight of Zr and Ti in the segregation 14 of each sample is shown in the column "(Ca+Sr) / (Zr+Ti)".

[0114] In Table 4B, the column "Ca, Sr total content ratio [molar parts]" shows the total content ratio of Ca and Sr in the segregation 14 in terms of oxides when the total of Hf, Ni, Mn, Ti, Si, Al, Ca, Zr, and Sr in terms of oxides in the segregation 14 of each sample is taken as 100 molar parts.

[0115] In Tables 5B, 6B, 7B and 8B, the ratio of the atomic weight of Mn to the total atomic weight of Mn and Si in the segregation 14 of each sample is shown in the column "Mn / (Mn+Si)".

[0116] In Tables 6B, 7B and 8B, the ratio of the atomic weight of Ni to the total atomic weight of Ni and Si in the segregation 14 of each sample is shown in the column "Ni / (Ni+Si)".

[0117] In Tables 7B and 8B, the average value of the number of segregations 14 per unit length of the internal electrode layer 12 is shown in the column "Number per unit length [pieces / mm]."

[0118] In Table 8B, the average grain size of the segregation 14 is shown in the "Grain size [μm]" column.

[0119] In Experiment 1, the crack occurrence rate after 24 hours of PCT (Pressure Cooker Test) and / or after 168 hours of PCT was calculated to evaluate the crack occurrence rate of the fabricated capacitor samples under a high temperature and humidity environment. Details are explained below.

[0120] <Crack occurrence rate after 24 hours of PCT> Capacitor samples were mounted on an FR4 substrate (glass epoxy substrate) using Sn-Ag-Cu solder and placed in a pressure cooker tank for an accelerated humidity test at 121°C and 95% humidity for 24 hours. The test was conducted on 100 capacitor samples. The number of capacitor samples that developed cracks is shown in Table 1C, Table 2C, Table 3C, Table 4C, Table 5C, or Table 6C. In this example, the crack occurrence rate after 24 hours of PCT was preferably 10% or less, and more preferably 3% or less.

[0121] <Crack occurrence rate after 168 hours of PCT> Capacitor samples were mounted on an FR4 substrate (glass epoxy substrate) using Sn-Ag-Cu solder and placed in a pressure cooker tank for an accelerated humidity test at 121°C and 95% humidity for 168 hours. The test was conducted on 100 capacitor samples. The number of capacitor samples in which cracks occurred is shown in Table 1C, Table 2C, or Table 3C. In this example, the crack occurrence rate after 168 hours of PCT was preferably 20% or less, and more preferably 6% or less.

[0122] (Experiment 2) Experiment 2 concerns Sample No. 1. In Experiment 2, capacitor samples were prepared in the same manner as Experiment 1, except that an internal electrode paste was used instead of the segregation-containing internal electrode paste, and the crack occurrence rates after 24 hours of PCT and after 168 hours of PCT were calculated. The results are shown in Table 1C.

[0123] Here, the internal electrode paste is similar to the segregation-containing internal electrode paste except that it does not contain the calcined powder of the segregation raw material.

[0124] (Experiment 3) Experiment 3 concerns sample number 31. In Experiment 3, a segregation-containing dielectric paste was prepared in addition to the dielectric paste. The segregation-containing dielectric paste is similar to the dielectric paste except that it contains calcined powder of the segregation raw material.

[0125] In Experiment 3, the ceramic green sheets had the following three-layer structure. First, a ceramic green sheet was formed using a dielectric paste. Next, a segregation-containing ceramic green sheet was formed on the ceramic green sheet using a segregation-containing dielectric paste. Furthermore, a ceramic green sheet was formed on the segregation-containing ceramic green sheet using a dielectric paste to form a three-layer ceramic green sheet.

[0126] In Experiment 3, the internal electrode paste of Experiment 2 was used instead of the segregation-containing internal electrode paste.

[0127] That is, a three-layer structure ceramic green sheet (internal electrode pattern-ceramic green sheet-segregation-containing ceramic green sheet-ceramic green sheet) on which an internal electrode pattern was formed using an internal electrode paste was laminated in multiple layers.

[0128] Except for the above, capacitor samples were prepared in the same manner as in Experiment 1, and the crack occurrence rates after 24 hours of PCT and after 168 hours of PCT were calculated. The results are shown in Table 3C.

[0129] (Experiment 4) Experiment 4 relates to sample number 32. In Experiment 4, the internal electrode pattern had the following three-layer structure. First, an internal electrode pattern was formed on a ceramic green sheet using an internal electrode paste. Next, a segregation-containing internal electrode pattern was formed on the internal electrode pattern using a segregation-containing internal electrode paste. Furthermore, an internal electrode pattern was formed on the segregation-containing internal electrode pattern using an internal electrode paste to form an internal electrode pattern with a three-layer structure.

[0130] Next, the ceramic green sheets on which the internal electrode patterns of a three-layer structure (internal electrode pattern-segregation-containing internal electrode pattern-internal electrode pattern-ceramic green sheet) were formed were laminated in multiple layers.

[0131] Except for the above, capacitor samples were prepared in the same manner as in Experiment 1, and the crack occurrence rates after 24 hours of PCT and after 168 hours of PCT were calculated. The results are shown in Table 3C.

[0132] (Experiment 7) Experiment 7 relates to sample numbers 71 to 74. In Experiment 7, the content of the calcined powder of the segregation raw material contained in the internal electrode paste was changed to change the number of segregations per unit length of the internal electrode layer, and the capacitor samples were obtained in the same manner as in Experiment 1, except that the crack occurrence rate after 24 hours of PCT was calculated. The results are shown in Table 7C.

[0133] (Experiment 8) Experiment 8 concerns sample numbers 81 to 84. In Experiment 8, the particle size of segregation 14 was changed by changing the grinding conditions of the calcined powder of the segregation raw material contained in the internal electrode paste, and the capacitor samples were obtained in the same manner as in Experiment 1, except that the crack occurrence rate after 24 hours of PCT was calculated. The results are shown in Table 8C.

[0134] [Table 1A]

[0135] Table 1B

[0136] Table 1C

[0137] Table 2A

[0138] Table 2B

[0139] Table 2C

[0140] Table 3A

[0141] Table 3B

[0142] Table 3C

[0143] Table 4A

[0144] Table 4B

[0145] Table 4C

[0146] Table 5A

[0147] Table 5B

[0148] Table 5C

[0149] Table 6A

[0150] Table 6B

[0151] Table 6C

[0152] Table 7A

[0153] Table 7B

[0154] Table 7C

[0155] Table 8A

[0156] [Table 8B]

[0157] [Table 8C]

[0158] When the element body did not have segregations containing Ca and / or Sr, Mn, Si, Ni, and O (sample numbers 1 to 8), the crack occurrence rate after 24 hours of PCT was 12% or more, and the crack occurrence rate after 168 hours of PCT was 31% or more.

[0159] In addition, the main component of the dielectric layer is (Ca 1-x Sr x ) m (Zr 1-y-z Ti y Hf z In the case of a compound that cannot be represented by )O3 (sample No. 11), the crack incidence rate after 24 hours of PCT was 16%, and the crack incidence rate after 168 hours of PCT was 37%.

[0160] Furthermore, the main component of the dielectric layer is (Ca 1-x Sr x ) m (Zr 1-y-z Ti y Hf z In the case of a compound that can be expressed by the formula (3), but where y and z do not satisfy the relationship 0.80≦1−yz≦1.0 (sample number 21), the crack incidence rate after 24 hours of PCT was 18%, and the crack incidence rate after 168 hours of PCT was 43%.

[0161] In contrast, the main component of the dielectric layer is a compound with the formula (Ca 1-x Sr x ) m (Zr 1-y-z Ti y Hf z)O3, where m is in the range of 0.9 to 1.1, x satisfies 0≦x≦1, y and z satisfy 0.80≦1−yz≦1.0, and the element body has segregations containing Ca and / or Sr, Mn, Si, Ni, and O (sample number 9), the crack occurrence rate after 24 hours of PCT was 0%, and the crack occurrence rate after 168 hours of PCT was 0%.

[0162] From the above, the main component of the dielectric layer is the composition formula (Ca 1-x Sr x ) m (Zr 1-y-z Ti y Hf z )O3, where m is in the range of 0.9 to 1.1, x satisfies 0≦x≦1, y and z satisfy 0.80≦1-yz≦1.0, and the element body has segregations containing Ca and / or Sr, Mn, Si, Ni, and O, it has been confirmed that this compound has the effect of suppressing the occurrence of cracks in a high-temperature, high-humidity environment. [Explanation of symbols]

[0163] 2... Multilayer ceramic capacitors 4... Element body 10... Ceramic layer (dielectric layer) 11…Lamination interface 12 … Internal electrode layer 12a … Electrode discontinuity 14 … segregation 6 … External electrode

Claims

1. An electronic component having an element body in which ceramic layers and internal electrode layers are laminated, The ceramic layer is mainly composed of a compound of the general formula ABO 3 The perovskite-type compound is represented by The perovskite compound has the composition formula (Ca 1-x Sr x ) m (Zr 1-y-z Ti y Hf z ) O 3 is a compound that can be represented by The m is in the range of 0.9 to 1.1, wherein x satisfies 0≦x≦1; the y and the z satisfy 0.80≦1−y−z≦1.0, the element body has segregation, The segregation includes Ca and / or Sr, Mn, Si, Ni, and O.

2. The electronic component according to claim 1 , wherein the segregation includes Al.

3. 2. The electronic component according to claim 1, wherein the element body has the segregation present in the electrode discontinuity portion of the internal electrode layer and / or the segregation present so as to contact the lamination interface between the ceramic layer and the internal electrode layer.

4. 2. The electronic component according to claim 1, wherein the ratio of the total atomic weight of Ca and Sr to the total atomic weight of Zr and Ti in the segregation {(Ca+Sr) / (Zr+Ti)} is 1.5 to 8.

0.

5. 2. The electronic component according to claim 1, wherein the ratio of the atomic weight of Mn to the total atomic weight of Mn and Si in the segregation {Mn / (Mn+Si)} is 0.02 or more and less than 0.

50.

6. 2. The electronic component according to claim 1, wherein the ratio of the atomic weight of Ni to the total atomic weight of Ni and Si in the segregation {Ni / (Ni+Si)} is 0.02 or more and less than 0.

6.

7. 4. The electronic component according to claim 3, wherein the average number of the segregations per unit length of the internal electrode layer is 0.05 pieces / μm or more and less than 0.5 pieces / μm.

8. 2. The electronic component according to claim 1, wherein the average grain size of the segregated particles is 0.1 μm to 15 μm.

9. 9. The electronic component according to claim 1, wherein the main component of the conductive material contained in the internal electrode layers is Ni and / or a Ni-based alloy.

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