Electronic component

Abstract

To provide electronic components capable of suppressing crack formation in high-temperature, high-humidity environments.SOLUTION: In an electronic component having an element main body with a ceramic layer and an internal electrode layer stacked together, the main components of the ceramic layer contains Ca and / or Sr, and Zr, and the element main body has a localized layer in which Mn is layered along the interface between the ceramic layer and the internal electrode layer.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 main components of the ceramic layer include Ca and / or Sr and Zr. The element body has a localized layer in which Mn is locally present in a layered manner along the laminated interface between the ceramic layer and the internal electrode layer.

[0007] Since the electronic component of the present invention has a predetermined localized layer in the element body, the generation of cracks can be suppressed in a high-temperature and high-humidity environment.

[0008] Preferably, LMn, CMn, and IMn satisfy CMn < LMn and IMn < LMn. The LMn is the content ratio in terms of the oxide of Mn when the total of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in the localized layer in terms of the oxide is 100 mol parts. The CMn is the content ratio in terms of the oxide of Mn when the total of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in the ceramic layer in terms of the oxide is 100 mol parts. The IMn is the content ratio in terms of the oxide of Mn when the total of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in the internal electrode layer in terms of the oxide is 100 mol parts.

[0009] Thereby, the generation of cracks can be further suppressed in a high-temperature and high-humidity environment.

[0010] Preferably, when comparing the content ratios in terms of the oxides of Al, Mg, Si, and Mn in the localized layer, Mn has the highest content ratio.

[0011] Thereby, the generation of cracks can be further suppressed in a high-temperature and high-humidity environment.

[0012] Preferably, LMn is 0.5 mol parts or more and 12.0 mol parts or less. The LMn is the content ratio in terms of the oxide of Mn when the total of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in the localized layer in terms of the oxide is 100 mol parts.

[0013] This makes it possible to further suppress the occurrence of cracks in a high-temperature and high-humidity environment.

[0014] Preferably, LMn / CMn is 1.25 or more and 15.0 or less, the L mn is the content ratio of Mn in terms of oxide when the total amount of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in terms of oxide in the localized layer is 100 parts by mole; The CMn is the content ratio of Mn in terms of oxide when the total of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in terms of oxide in the ceramic layer is 100 parts by mole.

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

[0016] Preferably, the thickness of the localized layer is 0.1 nm to 14 nm.

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

[0018] Preferably, the localized layer coverage is 80% or more, The localized layer coverage rate is the ratio of the total length of the localized layer in contact with the internal electrode layer along the lamination interface to the total length of the internal electrode layer along the lamination interface when a pair of the internal electrode layer and the localized layer in contact with each other are observed in a predetermined field of view of a cross section parallel to the lamination direction of the element body.

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

[0020] Preferably, the internal electrode layer coverage is 90% or more, The internal electrode layer coverage rate is the ratio of the total length of the internal electrode layers along the lamination interface to the total length of the ceramic layers along the lamination interface when a pair of the ceramic layers and the internal electrode layers that are in contact with each other are observed in a predetermined field of view of a cross section parallel to the lamination direction of the element body.

[0021] Preferably, the main component of the conductive material contained in the internal electrode layers is Ni and / or a Ni-based alloy.

[0022] This makes it possible to further suppress the occurrence of cracks in a high-temperature and high-humidity environment.

[0023] Preferably, 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 z satisfy the condition 0.80≦1−yz≦1.0. [Brief explanation of the drawings]

[0024] [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. [Figure 3A] FIG. 3A is a photograph according to an embodiment of the present invention. [Figure 3B] FIG. 3B is a graph according to an embodiment of the present invention. [Figure 4] FIG. 4 is a graph according to a comparative example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.

[0026] 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.

[0027] 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.

[0028] In this embodiment, the X-axis, Y-axis, and Z-axis are perpendicular to each other.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] The element ratio of oxygen (O) in the above composition formula may deviate slightly from the stoichiometric composition.

[0034] 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.

[0035] 2, the ceramic layer 10 includes main phase grains 10a formed of an oxide having a perovskite crystal structure made of a CSZT-based compound, and grain boundaries 10b. The grain boundaries 10b may also include segregated particles (not shown) having a different composition from the main phase grains 10a. The above-described minor components of the ceramic layer 10 may be contained in the main phase grains 10a as a solid solution, may be contained in the grain boundaries 10b, or may be contained in the segregated grains.

[0036] The average thickness Td (interlayer thickness) per ceramic layer 10 is not particularly limited, and is preferably 40 μm or less, and more preferably 20 μm or less, for example. The number of stacked ceramic layers 10 may be determined depending on the desired properties, and is not particularly limited. For example, it is preferably 20 layers or more, and more preferably 50 layers or more.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] The proportion 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 perpendicular 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.

[0041] In this embodiment, the internal electrode layer coverage is preferably 90% or more, and more preferably 95% or more.

[0042] 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 localized layer 16 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.

[0043] Furthermore, in addition to the above-mentioned conductive material, the internal electrode layers 12 may contain the ceramic components (for example, CSZT-based compounds) contained in the ceramic layers 10 as co-materials, 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.

[0044] 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 generally preferably about 1.0 μm to 100 μm.

[0045] 2 is a schematic cross-sectional view of the element body 4. In this embodiment, the element body 4 has a localized layer 16 in which Mn is uniformly localized in a layered form along the lamination interface 11 between the ceramic layer 10 and the internal electrode layer 12.

[0046] In this embodiment, LMn, CMn, and IMn satisfy CMn < LMn and IMn < LMn.

[0047] Here, LMn is the content ratio in terms of the oxide of Mn when the total of oxides of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in the localized layer 16 is 100 mole parts.

[0048] CMn is the content ratio in terms of the oxide of Mn when the total of oxides of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in the ceramic layer 10 is 100 mole parts.

[0049] IMn is the content ratio in terms of the oxide of Mn when the total of oxides of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in the internal electrode layer 12 is 100 mole parts.

[0050] Note that the conversion in terms of the oxide of Al means the conversion in terms of Al2O3.

[0051] The conversion in terms of the oxide of Si means the conversion in terms of SiO2.

[0052] The conversion in terms of the oxide of Ca means the conversion in terms of CaO.

[0053] The conversion in terms of the oxide of Ti means the conversion in terms of TiO2.

[0054] The conversion in terms of the oxide of Mn means the conversion in terms of MnO.

[0055] The conversion in terms of the oxide of Ni means the conversion in terms of NiO.

[0056] The conversion in terms of the oxide of Sr means the conversion in terms of SrO.

[0057] The conversion in terms of the oxide of Zr means the conversion in terms of ZrO2.

[0058] In the localized layer 16, when the content ratios of Al, Mg, Si and Mn in terms of oxides are compared, Mn has the highest content ratio.

[0059] The localized layer 16 does not have to be present over the entire surface of the stacking interface 11 , and the localized layer 16 does not have to be present over a portion of the stacking interface 11 .

[0060] When a pair of mutually contacting internal electrode layers 12 and localized layers 16 are observed in a predetermined field of view in a cross section (YZ plane or ZX cross section) parallel to the stacking direction (Z-axis direction) of the element body 4, the localized layer coverage is defined as the ratio of the total length of the localized layers 16 in contact with the internal electrode layers 12 along the stacking interface 11 to the total length of the internal electrode layers 12 along the stacking interface 11. It is preferable to observe in about five fields of view that satisfy the above predetermined field of view and calculate the average value of the localized layer coverage.

[0061] In this embodiment, the localized layer coverage is preferably 80% or more, and more preferably 90% or more.

[0062] The localized layer 16 may contain elements other than Mn, such as Al, Si, Ca, Ti, Ni, Sr, and / or Zr.

[0063] In this embodiment, LMn is preferably 0.5 parts by mol or more and 12.0 parts by mol or less, and more preferably 1.5 parts by mol or more and 5.0 parts by mol or less.

[0064] In this embodiment, LMn / CMn is preferably 1.25 or more and 15.0 or less, and more preferably 1.35 or more and 13.0 or less.

[0065] The thickness of the localized layer 16 in the stacking direction (Z-axis direction) is preferably 0.1 nm to 14 nm, and more preferably 0.15 nm to 6.0 nm. It is preferable to calculate the average thickness of the localized layer 16 by observing about five fields of view that satisfy the above-mentioned predetermined field of view.

[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 the localized layer 16 can be determined 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, a high-density portion can often be recognized as a bright contrast portion. Here, in the element body 4, the internal electrode layer 12 tends to be the densest portion, and the ceramic layer 10 tends to be the next densest portion. For this reason, the internal electrode layer 12 can often be recognized as a bright contrast portion, and the ceramic layer 10 can often be recognized as a darker contrast portion than the internal electrode layer 12.

[0068] From the above, the ceramic layers 10 and the internal electrode layers 12 in the element body 4 can be identified from the contrast brightness obtained by, for example, binarizing a cross-sectional photograph parallel to the lamination direction of the element body 4.

[0069] Based on the cross-sectional photograph parallel to the lamination direction of the element body 4, a line analysis is performed from an arbitrary point s in the ceramic layer 10 to an arbitrary point f in the internal electrode layer 12 adjacent to the ceramic layer 10, and the portion where Mn is localized near the lamination interface 11 is identified. Furthermore, a mapping image of Mn is obtained by STEM-EDS for the same field of view where the line analysis was performed, and the portion where Mn is uniformly localized in a layer along the lamination interface 11 can be determined as the localized layer 16. This method makes it possible to determine the presence or absence of the localized layer 16, the thickness of the localized layer 16, the coverage rate of the localized layer, etc.

[0070] The composition of the localized layer 16 can be measured by performing component analysis using an electron probe microanalyzer (EPMA) during cross-sectional observation. It is preferable to perform component analysis at at least three locations and calculate the composition of the localized layer 16 from the average value of the measurement results. In this embodiment, when performing component analysis using EPMA, an energy dispersive spectrometer (EDS) or a wavelength dispersive spectrometer (WDS) can be used as the X-ray spectrometer.

[0071] Next, an example of a method for manufacturing the multilayer ceramic capacitor 2 shown in FIGS. 1A and 1B will be described.

[0072] 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, an internal electrode paste that will become the internal electrode layers 12 after firing, and a Mn-containing internal electrode paste are prepared.

[0073] 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.

[0074] The Mn-containing internal electrode paste is prepared by kneading a metal material with a known binder and solvent. The metal material is obtained by mixing a Mn oxide with a conductive material. The Mn oxide may be any component that contributes to the Mn that constitutes the localized layer 16 after firing, such as MnO or MnCO.

[0075] The internal electrode paste is similar to the Mn-containing internal electrode paste, except that the metal material is only the conductive material, i.e., the internal electrode paste does not substantially contain any oxides of Mn.

[0076] Next, a Mn-containing internal electrode paste is applied in a predetermined pattern onto the ceramic green sheet by various printing methods such as screen printing or transfer methods to form a Mn-containing internal electrode pattern. Next, an internal electrode paste is applied in a predetermined pattern onto the Mn-containing internal electrode pattern to form an internal electrode pattern. Further, an Mn-containing internal electrode paste is applied in a predetermined pattern onto the internal electrode pattern to form a Mn-containing internal electrode pattern.

[0077] That is, an internal electrode pattern having a three-layer structure is formed on the ceramic green sheets.

[0078] Then, a plurality of ceramic green sheets on which the internal electrode patterns of a three-layer structure (Mn-containing internal electrode pattern-internal electrode pattern-Mn-containing internal electrode pattern-ceramic green sheet) are laminated, and then pressed in the lamination direction to obtain a mother laminate. At this time, the ceramic green sheets, the Mn-containing internal electrode pattern, and the internal electrode pattern are laminated so that the ceramic green sheets are positioned on the upper and lower surfaces of the mother laminate in the lamination 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 4 may be subjected to a reoxidation treatment (annealing) as needed. 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, a localized layer 16 in which Mn is uniformly localized in a layered form is formed along the lamination interface 11 between the ceramic layer 10 and the internal electrode layer 12.

[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 a predetermined localized layer 16 at the lamination interface 11, thereby improving the bonding strength between the ceramic layers 10 and the internal electrode layers 12 at the lamination interface 11. This makes it possible to suppress the occurrence of cracks originating from the lamination interface 11.

[0089] In particular, when the internal electrode layer 12 contains Ni, the Mn contained in the localized layer 16 and the Ni contained in the internal electrode layer 12 tend to form an alloy. Therefore, the localized layer 16 formed along the lamination interface 11 and containing Mn and the internal electrode layer 12 containing Ni can increase the bonding strength by alloying Mn and Ni.

[0090] 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 they have a lower temperature change rate of the dielectric constant than electronic components in which the ceramic layer 10 is made of barium titanate (hereinafter referred to as a "BT-based compound").

[0091] 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 10 is a BT-based compound.

[0092] Furthermore, when the main component of the ceramic layer 10 is a CSZT-based compound, the ceramic layer 10 may contain Mn, and 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 localized layer 16, and therefore, the Mn contained in the main phase grains 10a and / or grain boundaries 10b of the ceramic layer 10 and the Mn contained in the localized layer 16 interdiffuse, thereby increasing the bonding strength between the ceramic layer 10 and the localized layer 16.

[0093] 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.

[0094] In the above embodiment, the localized layer 16 is formed using the Mn-containing internal electrode paste, but there is no particular limitation on the method for forming the localized layer 16. Other examples of methods for forming the localized layer 16 include sputtering, vacuum deposition, and chemical vapor deposition (CVD).

[0095] When the localized layer 16 is formed by sputtering, the localized layer 16 is formed on a ceramic green sheet by sputtering, an internal electrode pattern is printed on the localized layer 16, and another localized layer 16 is formed on the internal electrode pattern by sputtering. That is, a plurality of ceramic green sheets, each having an internal electrode pattern sandwiched between two localized layers 16, are stacked, and then pressed in the stacking direction to obtain a mother laminate. The subsequent steps are the same as those in the above embodiment.

[0096] Furthermore, in this embodiment, the multilayer ceramic capacitor 2 is exemplified as an electronic component, but the electronic component of the present invention may also be, for example, a bandpass filter, a multilayer three-terminal filter, a piezoelectric element, a thermistor, a varistor, or the like.

[0097] 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]

[0098] The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

[0099] (Experiment 1) Experiment 1 concerns sample numbers 5 to 9.

[0100] In Experiment 1, a multilayer ceramic capacitor 2 was fabricated according to the following procedure. First, a dielectric paste, a Mn-containing internal electrode paste, and an internal electrode paste were prepared, and these pastes were used to fabricate green chips by the sheet method according to the method described in the embodiment.

[0101] In this case, the dielectric raw material contained in the dielectric paste was a raw material having the composition shown in Table 1. Furthermore, SiO2, Al2O3, and MnCO3 were used as secondary component compounds contained in the dielectric paste.

[0102] The conductive material of the metal material contained in the Mn-containing internal electrode paste and the internal electrode paste was Ni.

[0103] 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.

[0104] The end faces of the element body 4 obtained as described above were polished, and an external electrode paste was applied and baked to form the external electrodes 6.

[0105] 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.

[0106] In addition, a sample for destructive testing was extracted from the capacitor sample related to sample number 5 in experiment 1, and cross-sectional observation was performed using the sample by STEM. 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 HAADF images of the STEM. The measurement results were as follows.

[0107] Average thickness Td of ceramic layer 10: 2.5 μm Average thickness Te of the internal electrode layer 12: 1.1 μm

[0108] In addition, in the above cross-sectional observation, the presence or absence of the localized layer 16 was confirmed, and component analysis of the ceramic layer 10, the internal electrode layer 12, and the localized layer 16 was performed by point analysis using STEM-EDS.

[0109] As a result, it was confirmed that the composition of the ceramic layer 10 generally matched the composition of the dielectric raw materials and by-component compounds contained in the dielectric paste and the measurement results. Also, it was confirmed that the internal electrode layer 12 mainly contained Ni, which was the conductive material contained in the internal electrode paste.

[0110] Therefore, in each of the following experiments, it was also estimated that the composition of the ceramic layer 10 matched the composition of the dielectric raw materials and by-component compounds contained in the dielectric paste and the measurement results. Also, it was estimated that the internal electrode layer 12 mainly contained Ni, which was the conductive material contained in the internal electrode paste.

[0111] Furthermore, when using the Mn-containing internal electrode paste, in the localized layer ①, when comparing the content ratios in terms of oxides of Al, Mg, Si, and Mn, it was confirmed that Mn had the highest content ratio. Therefore, when using the Mn-containing internal electrode paste, it was estimated that in the localized layer 16, when comparing the content ratios in terms of oxides of Al, Mg, Si, and Mn, Mn had the highest content ratio.

[0112] Table 1 shows the presence or absence of the localized layer. In Tables 1 to 5, when CMn < LMn and IMn < LMn are satisfied and when comparing the content ratios in terms of oxides of Al, Mg, Si, and Mn in the localized layer, if Mn has the highest content ratio, the column of "Presence / Absence" of the "Localized Layer" is marked as "Present", and if the above conditions are not satisfied, the column of "Presence / Absence" of the "Localized Layer" is marked as "Absent".

[0113] Also, in Tables 1 to 5, when comparing the content ratios in terms of oxides of Al, Mg, Si, and Mn in the localized layer, the element with the highest content ratio is recorded in the column of "Element" of the "Localized Layer".

[0114] Note: There seems to be a "①" in the translation of item which might be a typo in the original text. It should probably be "16".In all of the capacitor samples in Tables 1 to 5, the internal electrode layer coverage was 90% or more.

[0115] In Experiment 1, the crack occurrence rate after 24 hours of PCT (Pressure Cooker Test) and after 168 hours of PCT were calculated to evaluate the crack occurrence rate of the fabricated capacitor samples in a high temperature and high humidity environment. Details are explained below.

[0116] <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 in which cracks occurred is shown in Table 1. In this example, the crack occurrence rate after 24 hours of PCT was preferably 10% or less, and more preferably 3% or less.

[0117] <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 to undergo 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 1. In this example, the crack occurrence rate after 168 hours of PCT was preferably 20% or less, and more preferably 6% or less.

[0118] (Experiment 1a) Experiment 1a concerns sample number 1. In Experiment 1a, capacitor samples were prepared in the same manner as in Experiment 1, except that the internal electrode pattern was not a three-layer structure but a single-layer structure with only the internal electrode pattern. The presence or absence of a localized layer was determined, and the crack occurrence rates after 24 hours of PCT and after 168 hours of PCT were calculated. The results are shown in Table 1.

[0119] That is, in Experiment 1a, the Mn-containing internal electrode pattern was not formed using the Mn-containing internal electrode paste.

[0120] (Experiment 1b) Experiment 1b concerns sample number 2. In Experiment 1b, a capacitor sample was prepared in the same manner as Experiment 1, except that an Al-containing internal electrode paste was used instead of a Mn-containing internal electrode paste to form a three-layer structure for the internal electrode pattern. The presence or absence of a localized layer and the elements therein were determined, and the crack occurrence rates after 24 hours of PCT and after 168 hours of PCT were calculated. The results are shown in Table 1.

[0121] The Al-containing internal electrode paste is similar to the Mn-containing internal electrode paste, except that it contains Al oxide (Al2O3) instead of Mn oxide.

[0122] In Sample No. 2 (Experiment 1b), a localized layer 16 that meets the definition of the localized layer 16 described above could not be confirmed, but Al was localized in a layer along the lamination interface 11, and therefore "Present" is entered in the "Presence / Absence" column for "Localized Layer" in Table 1, and "Al" is entered in the "Element" column for "Localized Layer". That is, in Experiment 1b, which used an Al-containing internal electrode paste, it was confirmed that in the localized layer 16, when the content ratios of Al, Mg, Si, and Mn converted into oxides were compared, Al had the highest content ratio.

[0123] (Experiment 1c) Experiment 1c concerns sample number 3. In Experiment 1c, a capacitor sample was prepared in the same manner as Experiment 1, except that a Mg-containing internal electrode paste was used instead of a Mn-containing internal electrode paste to form a three-layer structure for the internal electrode pattern. The presence or absence of a localized layer and the elements therein were determined, and the crack occurrence rates after 24 hours of PCT and after 168 hours of PCT were calculated. The results are shown in Table 1.

[0124] The Mg-containing internal electrode paste is similar to the Mn-containing internal electrode paste, except that it contains an oxide of Mg (MgO) instead of an oxide of Mn.

[0125] In Sample No. 3 (Experiment 1c), a localized layer 16 that meets the definition of the localized layer 16 described above could not be confirmed, but Mg was localized in a layer along the lamination interface 11, and therefore "Present" is entered in the "Presence / Absence" column for "Localized Layer" in Table 1, and "Mg" is entered in the "Element" column for "Localized Layer". That is, in Experiment 1c, which used a Mg-containing internal electrode paste, it was confirmed that in the localized layer 16, when the content ratios of Al, Mg, Si, and Mn converted into oxides were compared, Mg had the highest content ratio.

[0126] (Experiment 1d) Experiment 1d concerns sample number 4. In Experiment 1d, a capacitor sample was prepared in the same manner as Experiment 1, except that a Si-containing internal electrode paste was used instead of a Mn-containing internal electrode paste to form a three-layer structure for the internal electrode pattern. The presence or absence of a localized layer and the elements therein were determined, and the crack occurrence rates after 24 hours of PCT and after 168 hours of PCT were calculated. The results are shown in Table 1.

[0127] The Si-containing internal electrode paste is similar to the Mn-containing internal electrode paste, except that it contains Si oxide (SiO2) instead of Mn oxide.

[0128] In Sample No. 4 (Experiment 1d), a localized layer 16 that meets the definition of the localized layer 16 described above could not be confirmed, but Si was localized in a layer along the stacking interface 11, and therefore "Present" is entered in the "Presence / Absence" column for "Localized Layer" in Table 1, and "Si" is entered in the "Element" column for "Localized Layer". That is, in Experiment 1d, which used a Si-containing internal electrode paste, it was confirmed that in the localized layer 16, when the content ratios of Al, Mg, Si, and Mn converted into oxides were compared, Si had the highest content ratio.

[0129] (Experiment 2) Experiment 2 concerns each sample in Table 2. In Experiment 2, capacitor samples were prepared in the same manner as Experiment 1, except that LMn was changed by varying the amount of Mn oxide contained in the Mn-containing internal electrode paste. The presence or absence of a localized layer and its elements were determined, and the crack occurrence rate after 24 hours of PCT was calculated. Table 2 shows the results of measuring LMn for each sample in Experiment 2.

[0130] (Experiment 3) Experiment 3 concerns each sample in Table 3. In Experiment 3, capacitor samples were prepared in the same manner as Experiment 1, except that CMn was changed by varying the amount of Mn oxide contained in the dielectric paste, and the crack occurrence rate after 24 hours of PCT was calculated. In Experiment 3, LMn and LMn / CMn of each sample were measured, and the results are shown in Table 3.

[0131] (Experiment 4) Experiment 4 concerns each sample in Table 4. In Experiment 4, capacitor samples were prepared in the same manner as in Experiment 1, except that the thickness of the localized layer 16 was changed by changing the coating thickness of the Mn-containing internal electrode paste, and the crack occurrence rate after 24 hours of PCT was calculated. In Experiment 4, the LMn, LMn / CMn, and thickness of the localized layer of each sample were measured, and the results are shown in Table 4.

[0132] (Experiment 5) Experiment 5 concerns each sample in Table 5. In Experiment 5, capacitor samples were prepared in the same manner as Experiment 1, except that the localized layer coverage was changed by changing the amount of Mn-containing internal electrode paste applied to the ceramic green sheet, thereby changing the amount of Mn-containing internal electrode pattern attached to the internal electrode pattern, and the crack occurrence rate after 24 hours of PCT was calculated. In Experiment 5, the LMn, LMn / CMn, localized layer thickness, and localized layer coverage of each sample were measured, and the results are shown in Table 5.

[0133] 3A and 3B relate to sample number 23. FIG. 3A is a STEM HAADF image of the vicinity of the stacking interface 11 of sample number 23.

[0134] 3B shows the results of a line analysis along the black line from point s on the ceramic layer 10 in FIG. 3A to an arbitrary point f on the internal electrode layer 12 adjacent to the ceramic layer 10. The X-axis in FIG. 3B indicates the position from point s to point f, in units of nm. That is, point s is at 0 nm on the X-axis, and point f is at 100 nm on the X-axis.

[0135] The Y axis in FIG. 3B shows the content ratio of each element in terms of oxide when the total of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in terms of oxide is taken as 100 parts by mole.

[0136] In Figure 3B, ● indicates the content ratio of Al in terms of oxide (Al2O3 equivalent), ▲ indicates the content ratio of Si in terms of oxide (SiO2 equivalent), and ■ indicates the content ratio of Mn in terms of oxide (MnO equivalent).

[0137] Figure 4 relates to sample number 1. Figure 4 shows the results of a line analysis from point s in the ceramic layer to an arbitrary point f in the internal electrode layer adjacent to the ceramic layer. In Figure 4, the X-axis indicates the position from point s to point f, in units of nm. That is, point s is at 0 nm on the X-axis, and point f is at 100 nm on the X-axis.

[0138] The Y axis in FIG. 4 shows the content ratio of each element in terms of oxide when the total of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in terms of oxide is taken as 100 parts by mole.

[0139] In Figure 4, ● indicates the content ratio of Al converted into oxide (Al2O3 converted), ▲ indicates the content ratio of Si converted into oxide (SiO2 converted), and ■ indicates the content ratio of Mn converted into oxide (MnO converted).

[0140] [Table 1]

[0141] [Table 2]

[0142] [Table 3]

[0143] [Table 4]

[0144] [Table 5]

[0145] When the element body did not have a localized layer in which Mn was localized in layers along the lamination interface between the dielectric layer and the internal electrode layer (sample numbers 1 to 4), 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.

[0146] Furthermore, when the main components of the dielectric layer did not contain Ca and / or Sr and Zr (sample number 9), the crack occurrence rate after 24 hours of PCT was 16%, and the crack occurrence rate after 168 hours of PCT was 27%.

[0147] In contrast, when the main components of the dielectric layer included Ca and / or Sr and Zr, and the element body had a localized layer in which Mn was localized in layers along the lamination interface between the ceramic layer and the internal electrode layer (sample numbers 6 to 8), the crack occurrence rate was 0% after 24 hours of PCT, and 0% after 168 hours of PCT.

[0148] From the above, it was confirmed that when the main components of the dielectric layer contain Ca and / or Sr and Zr, and the element body has a localized layer in which Mn is localized in layers along the lamination interface between the ceramic layer and the internal electrode layer, there is an effect of suppressing the occurrence of cracks in a high-temperature, high-humidity environment. [Explanation of symbols]

[0149] 2... Multilayer ceramic capacitors 4... Element body 10... Ceramic layer (dielectric layer) 10a…Main phase particles 10b … Grain boundary 11…Lamination interface 12 … Internal electrode layer 12a … Electrode discontinuity 16 … localized layer 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 contains Ca and / or Sr and Zr as a main component, The element body is an electronic component having a localized layer in which Mn is localized in a layered form along the lamination interface between the ceramic layer and the internal electrode layer.

2. LMn, CMn, and IMn satisfy CMn<LMn and IMn<LMn, the LMn is the content ratio of Mn in terms of oxide when the total of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in terms of oxide in the localized layer is 100 parts by mole; The C Mn represents a content ratio of Mn in terms of oxide when the total amount of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in terms of oxide in the ceramic layer is 100 parts by mole, 2. The electronic component according to claim 1, wherein the IMn is a content ratio of Mn in terms of oxide when the total of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in terms of oxide in the internal electrode layer is 100 parts by mole.

3. 2. The electronic component according to claim 1, wherein when the contents of Al, Mg, Si and Mn in the localized layer are compared in terms of oxide, Mg has the highest content.

4. LMn is 0.5 parts by mol or more and 12.0 parts by mol or less, 2. The electronic component according to claim 1, wherein the LMn is a content ratio of Mn, calculated as an oxide, when the total of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr, calculated as oxides, in the localized layer is 100 parts by mole.

5. LMn / CMn is 1.25 or more and 15.0 or less, the LMn is the content ratio of Mn in terms of oxide when the total of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr in terms of oxide in the localized layer is 100 parts by mole; 2. The electronic component according to claim 1, wherein the C₁₄Mn is a content ratio of Mn, calculated as an oxide, when the total of Al, Si, Ca, Ti, Mn, Ni, Sr, and Zr, calculated as oxides, in the ceramic layer is 100 parts by mole.

6. 2. The electronic component according to claim 1, wherein the localized layer has a thickness of 0.1 nm to 14 nm.

7. The localized layer coverage is 80% or more, 2. The electronic component according to claim 1, wherein the localized layer coverage is a ratio of a total length of the localized layer in contact with the internal electrode layer along the lamination interface to a total length of the internal electrode layer along the lamination interface when a pair of the internal electrode layer and the localized layer in contact with each other are observed in a predetermined field of view of a cross section parallel to the lamination direction of the element body.

8. The internal electrode layer coverage is 90% or more, 2. The electronic component according to claim 1, wherein the internal electrode layer coverage is a ratio of a total length of the internal electrode layers along the lamination interface to a total length of the ceramic layers along the lamination interface when a pair of the ceramic layers and the internal electrode layers contacting each other are observed in a predetermined field of view of a cross section parallel to the lamination direction of the element body.

9. 2. 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.

10. 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; 10. The electronic component according to claim 1, wherein y and z satisfy 0.80≦1−y−z≦1.0.

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