Electronic component

Abstract

To provide an electronic component comprising a dielectric layer in which a dielectric composition, which hardly causes structural defects such as cracks even when exposed to severe environments, is formed in layers.SOLUTION: There is provided an electronic component comprising a dielectric layer in which a dielectric composition is formed in layers and an electrode layer comprising nickel as a main component, wherein the dielectric composition comprises, as a main component, a composite oxide represented by the general formula, AaBbC4O15+α, in which A represents a group of elements including at least barium, B represents a group of elements including at least zirconium, C represents a group of elements including at least niobium, a is 3.05 or more and b is 1.01 or more and nickel, and the dielectric composition has a main phase composed of a composite oxide and a first phase different from the main phase and containing nickel, silicon and oxygen.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an electronic component having a dielectric layer formed of a dielectric composition in a layered form. [Background technology]

[0002] The electronic circuits or power supply circuits incorporated in electronic devices are equipped with a large number of electronic components, such as multilayer capacitors, that utilize the dielectric properties exhibited by dielectrics. Barium titanate-based dielectric compositions are widely used as the materials that make up the dielectrics of such electronic components (dielectric materials).

[0003] However, in recent years, the applications of electronic components have expanded, and there is a demand for them to function satisfactorily even in high-voltage environments. However, in such environments, the dielectric properties of barium titanate-based dielectric compositions deteriorate, making them unable to adequately cope with such environments. Therefore, there is a demand for dielectric compositions that can exhibit high dielectric properties even in such applications.

[0004] Patent Document 1 discloses a dielectric composition other than a barium titanate-based dielectric composition, which is represented by the general formula Ba6Ti2Nb8O 30 The present application discloses a dielectric composition in which Ba, Ti and Nb in a ferroelectric material represented by the formula (I) are partially substituted with other elements. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 3-274607 Summary of the Invention [Problem to be solved by the invention]

[0006] However, dielectric compositions having a structure similar to that of the ferroelectric material described in Patent Document 1 have the problem that they are prone to structural defects such as cracks when exposed to harsh environments.

[0007] The present invention has been made in view of the above circumstances, and aims to provide an electronic component including a dielectric layer formed of a dielectric composition that is resistant to structural defects such as cracks even when exposed to a harsh environment. [Means for solving the problem]

[0008] The aspects of the present invention are as follows.

[0009] [1] An electronic component comprising a dielectric layer formed of a dielectric composition in a layered form and an electrode layer containing nickel as a main component, The dielectric composition has the general formula A a B b C4O 15+ A represents an element group containing at least barium, B represents an element group containing at least zirconium, C represents an element group containing at least niobium, a is 3.05 or more, b is 1.01 or more, and the composite oxide as a main component and nickel are contained, The dielectric composition is an electronic component having a main phase composed of a composite oxide and a first phase that contains a composite oxide having nickel, silicon, and oxygen and is different from the main phase.

[0010] [2] The electronic device according to [1], wherein the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition is 0.005 or more and 0.02 or less.

[0011] [3] The electronic component according to [1] or [2], wherein in the first phase, the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the first phase is 0.01 or more and 0.03 or less.

[0012] [4] 1 μm in the cross section of the dielectric composition 2 The electronic component according to any one of [1] to [3], wherein the number of the first phases present therein is 0.05 or more and 1 or less.

[0013] [5] The electronic component according to any one of [1] to [4], wherein the average value of the area-equivalent circle diameter of the first phase is in the range of 0.05 μm or more and 0.5 μm or less.

[0014] [6] The electronic component includes an inner layer region in which dielectric layers and internal electrode layers are alternately stacked; an outer layer region that is arranged on at least one end face of the inner layer region in the lamination direction of the dielectric layers and the internal electrode layers and is made of a dielectric composition; The electronic component according to any one of [1] to [5], wherein the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition located in the outer layer region is smaller than the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition located in the inner layer region.

[0015] [7] The electronic component according to [6], wherein in the inner layer region, the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition located near the interface between the dielectric layer and the internal electrode layer is greater than the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition located at the midpoint between adjacent internal electrode layers in the stacking direction. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view showing a multilayer capacitor as an electronic component according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing a cross section of the multilayer capacitor taken along line II-II in FIG. [Figure 3] FIG. 3 is a schematic diagram showing a cross section of the multilayer capacitor taken along line III-III in FIG. [Figure 4] FIG. 4 is a schematic diagram showing a cross section of the dielectric composition. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below based on specific embodiments in the following order. 1. Electronic Components 1.1. Overall structure of multilayer capacitor 1.2.Dielectric Layer 1.3. Internal electrode layer 1.4.External electrode 2. Dielectric composition 2.1. Complex oxides 2.2. Phase 1 2.3. Identification of the first phase 2.4. Inner and outer layer regions 3. Manufacturing method of multilayer capacitors 4. Summary of this embodiment 5. Variations

[0018] (1. Electronic Components) The electronic component according to this embodiment is an electronic component having a dielectric layer exhibiting predetermined dielectric properties and electrodes. Such an electronic component may be an electronic component having a configuration in which one dielectric layer is sandwiched between electrodes, or may be a multilayer electronic component in which multiple dielectric layers are stacked with electrode layers interposed therebetween. In this embodiment, a multilayer capacitor will be described as an example of a multilayer electronic component.

[0019] (1.1. Overall structure of multilayer capacitor) FIG. 1 shows a multilayer capacitor 1 as an example of a multilayer electronic component according to this embodiment. In FIG. 1, the X-axis, Y-axis, and Z-axis are perpendicular to one another. The multilayer capacitor 1 includes an element body 10 and external electrodes 4 formed on both end faces of the element body 10 that are perpendicular to the X-axis. The element body 10 is typically shaped like a rectangular parallelepiped. There are no particular limitations on the dimensions of the element body 10, and the dimensions may be appropriate depending on the application.

[0020] Fig. 2 shows a cross section of the multilayer capacitor 1 taken along line II-II in Fig. 1, and Fig. 3 shows a cross section of the multilayer capacitor 1 taken along line III-III in Fig. 1. As shown in Figs. 2 and 3, the element body 10 has an inner layer region 11 and an outer layer region 12.

[0021] As shown in Figures 2 and 3, the inner layer region 11 is a region in which dielectric layers (inner dielectric layers) 2a belonging to the inner layer region and internal electrode layers 3 are alternately laminated. The outer layer region 12 is a region of the surface of the inner layer region 11 that is arranged on both end faces perpendicular to the Z axis. The outer layer region 12 is made of a dielectric composition and is a region in which no internal electrode layers 3 are formed. The outer layer region 12 is usually made of laminated outer dielectric layers 2b. Note that, hereinafter, the "inner dielectric layer" and the "outer dielectric layer" may be collectively referred to as the "dielectric layer".

[0022] (1.2. Dielectric Layer) The dielectric layer 2 is a layer of a dielectric composition described below. As a result, a multilayer capacitor including the dielectric layer 2 is less likely to suffer from structural defects such as cracks even when exposed to harsh environments.

[0023] The thickness of each inner dielectric layer 2a (interlayer thickness) is not particularly limited and can be set arbitrarily depending on the desired characteristics, application, etc. Usually, the interlayer thickness is preferably 20 μm or less, more preferably 10 μm or less. The number of laminations of the inner dielectric layers 2a in the inner layer region 11 can also be set arbitrarily. For example, in the case of a multilayer capacitor used for characteristic evaluation, the number of laminations may be on the order of several layers. On the other hand, in the case of a multilayer capacitor to be incorporated into a specific product, the number of laminations may be, for example, 20 or more.

[0024] (1.3. Internal electrode layer) 2, in this embodiment, the internal electrode layers 3 are stacked so that their ends are exposed on a pair of opposing surfaces of the element body 10. Specifically, the internal electrode layers 3 are arranged so that the ends of every other layer are exposed on the same surface of the pair of opposing surfaces of the element body 10.

[0025] The internal electrode layers 3 are made of a conductive material. In this embodiment, the main component of the internal electrode layers 3 is nickel (Ni) or a Ni-based alloy. Note that the Ni or Ni-based alloy may contain various trace components such as P in an amount of about 0.1 mass % or less. The internal electrode layers 3 may also be formed using a commercially available electrode paste. The thickness of the internal electrode layers 3 may be determined appropriately depending on the application, etc.

[0026] (1.4.External electrode) The external electrodes 4 are made of a conductive material. Known conductive materials such as nickel (Ni), copper (Cu), tin (Sn), silver (Ag), palladium (Pd), platinum (Pt), gold (Au), alloys of these, conductive resins, etc. may be used as the external electrodes 4. The thickness of the external electrodes 4 may be determined appropriately depending on the application, etc.

[0027] (2. Dielectric Composition) In this embodiment, the dielectric composition constituting the dielectric layer contains a composite oxide containing at least barium (Ba), zirconium (Zr), and niobium (Nb) as a main component. The composite oxide preferably accounts for 80% by mass or more, and more preferably 90% by mass or more, of the dielectric composition (100% by mass). Furthermore, the composite oxide preferably has a tungsten bronze structure.

[0028] Furthermore, in this embodiment, the dielectric composition contains nickel (Ni). The dielectric composition containing Ni means that the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition is 0.002 or more. The Ni contained in the dielectric composition easily bonds with the Ni contained in the internal electrode layers, increasing the bonding strength between the dielectric layers and the internal electrode layers. As a result, it is possible to suppress the occurrence of cracks at the interface between the dielectric layers and the internal electrode layers. Ni may be contained in the complex oxide, which is the main component, or may be contained in a component other than the complex oxide.

[0029] In the dielectric composition, the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition (hereinafter referred to as "(Ni / all elements)whole It is preferable that the % of Ni content is 0.005 or more and 0.02 or less. (Ni / all elements) whole may be 0.006 or more and 0.015 or less.

[0030] (2.1. Complex oxides) The elements other than oxygen contained in the composite oxide are divided into three element groups ("A", "B", and "C"). In this embodiment, the composite oxide has the general formula A a B b C4O 15+ A general formula is a generalized chemical formula expressed using element symbols and the ratio of the number of atoms thereof, and is expressed using symbols indicating a specific group of elements and the ratio of the element symbols and the number of atoms thereof.

[0031] "A" is a group of elements that includes at least barium (Ba), and in this embodiment, is preferably a group of elements consisting of divalent elements that occupy the gaps between oxygen octahedra in the tungsten bronze structure. "B" is a group of elements that includes at least zirconium (Zr), and in this embodiment, is preferably a group of elements consisting of tetravalent elements that form oxygen octahedra in the tungsten bronze structure. "C" is a group of elements that includes at least niobium (Nb), and in this embodiment, is preferably a group of elements consisting of pentavalent elements that form oxygen octahedra in the tungsten bronze structure. Furthermore, "a" in the above general formula indicates the atomic ratio of "A" when four atoms of the element that makes up "C" in the general formula are contained, and "b" in the above general formula indicates the atomic ratio of "B" when four atoms of the element that makes up "C" in the general formula are contained.

[0032] In this embodiment, "a" is 3.05 or more. Furthermore, "a" is preferably 3.10 or more. The upper limit of "a" is set within a range in which the effects of the present invention can be obtained. For example, "a" may be 3.50 or less, or 3.30 or less.

[0033] In this embodiment, "b" is 1.01 or more. Furthermore, "b" is preferably 1.05 or more. The upper limit of "b" is set within a range in which the effects of the present invention can be obtained. For example, "b" may be 1.50 or less, or 1.30 or less.

[0034] The above composite oxides have a stoichiometric composition of the general formula A3B1C4O 15 In the composite oxide represented by the formula (I), "A" and "B" are contained in excess of "C" at a predetermined ratio. As a result, the composite oxide can exhibit high resistivity even when fired in a reducing atmosphere, and can prevent the dielectric composition from becoming a semiconductor or a conductor. In other words, even when nickel or a nickel-based alloy that oxidizes when fired in an oxidizing atmosphere is used as the conductive material for the electrode, electronic components having a dielectric composition containing the composite oxide as a main component can exhibit sufficient dielectric properties.

[0035] In this composite oxide, the amount of oxygen (O) may vary depending on the composition ratio of "A," "B," and "C," oxygen defects, etc. Therefore, in this embodiment, 15 The deviation of oxygen from the stoichiometric ratio is represented by "α". The range of "α" is, for example, about -1 or more and 1 or less. That is, in the general formula A a B b C4O 15+ In terms of α, "15+α" is within the range of 14 or greater and 16 or less.

[0036] In this embodiment, "A" may be Ba alone or may contain an element other than Ba. The element other than Ba ​​may be at least one selected from the divalent elements Ca and Sr. When "A" contains an element other than Ba, the ratio of the number of atoms of the elements other than Ba ​​to the total number of atoms of all elements constituting "A" is preferably 0.20 or less, and more preferably 0.10 or less.

[0037] "B" may be Zr alone, or may contain a tetravalent element other than Zr, or may contain Mg or Ni. Since the ionic radius of "B" is smaller than the ionic radius of "A", Mg and Ni, which are divalent elements with small ionic radii, may be included in "B". Examples of tetravalent elements other than Zr include at least one selected from Ti and Hf. When "B" contains a tetravalent element other than Zr, the ratio of the number of atoms of the tetravalent element other than Zr to the total number of atoms of all elements constituting "B" is preferably 0.25 or less, and more preferably 0.125 or less in total.

[0038] "C" may be Nb alone, or may contain a pentavalent element other than Nb, or may contain Mg or Ni. As with "B," the ionic radius of "C" is smaller than that of "A," so Mg and Ni, which are divalent elements with small ionic radii, may be included in "C." That is, Mg and Ni may be included in both "B" and "C," or in either one of them. An example of a pentavalent element other than Nb is Ta. When "C" contains a pentavalent element other than Nb, the ratio of the number of atoms of the pentavalent element other than Nb to the total number of atoms of all elements constituting "C" is preferably 0.10 or less in total.

[0039] When at least one of "B" and "C" contains Mg, the valence of Mg is smaller than that of the elements contained in "B" and "C", and therefore Mg acts as an acceptor. As a result, the reduction resistance of the composite oxide tends to improve.

[0040] When at least one of "B" and "C" contains Ni, the complex oxide tends to bond more easily with Ni contained in the internal electrode layer, and the bonding strength between the dielectric composition and the internal electrode layer tends to increase.

[0041] (2.2. Phase 1) FIG. 4 shows a cross section of the dielectric composition. As shown in FIG. 4, the dielectric composition 2 includes a main phase 20 and grain boundaries 30 present between the main phases 20. The main phase 20 is a particle (main component particle) composed of the above-mentioned composite oxide, which is the main component. The average particle size of the main component particles is, for example, within a range of 0.01 to 10 μm. The grain boundary 30 is a region containing components other than the main component, components diffused from the main component, etc. The grain boundary 30 includes a region (two-particle grain boundary) 31 present between two adjacent main phases, a region (grain boundary triple junction) 32 present between three or more main phases, etc. In this embodiment, a first phase 41 different from the main phase 20 is present in the grain boundary 30. The first phase 41 is mainly present at the grain boundary triple junction. A phase other than the first phase may be present in the grain boundary. An example of such a phase is a phase composed of an oxide containing zirconium.

[0042] The first phase contains at least nickel (Ni), silicon (Si), and oxygen (O), which in this embodiment form a composite oxide (Ni-Si-O). The presence of the first phase at the grain boundaries can suppress the progression of cracks at the grain boundaries.

[0043] In this embodiment, the first phase may further contain at least one selected from barium (Ba), magnesium (Mg), strontium (Sr), and calcium (Ca). That is, the first phase may be a composite oxide containing these elements, Ni, and Si ((Ba, Mg, Sr, Ca)-Ni-Si-O). (Ba, Mg, Sr, Ca)-Ni-Si-O can also fulfill a role similar to that of Ni-Si-O. Among Ba, Mg, Sr, and Ca, Ba and Mg or Ba are preferred. That is, the first phase may be a composite oxide containing Ba, Mg, Ni, and Si (Ba-Mg-Ni-Si-O), or a composite oxide containing Ba, Ni, and Si (Ba-Ni-Si-O).

[0044] As shown in FIG. 4, the first phases 41 are scattered among the main phases 20. In this embodiment, the first phases are dispersed over a unit area (1 μm ) in the cross section of the dielectric composition. 2) may be present in an amount of 0.05 to 1 per 1 μm. This can further suppress the progression of cracks. 2 The number of the first phases per particle may be 0.08 or more and 0.82 or less.

[0045] Furthermore, when the diameter of a circle having the same area as the area of ​​the first phase is taken as the equivalent-area circle diameter of the first phase, the average value of the equivalent-area circle diameter may be in the range of 0.05 μm to 0.5 μm. This can further suppress the progression of cracks. The average value of the equivalent-area circle diameter may be in the range of 0.06 μm to 0.38 μm.

[0046] In the first phase, the ratio of the number of Ni atoms to the total number of atoms of all elements contained in the first phase (hereinafter referred to as "(Ni / all elements) 1st In the first phase, (Ni / all elements) 1st By keeping the content of Ni within the above range, the progression of cracks can be further suppressed. (Ni / all elements) 1st In this embodiment, "(Ni / all elements)" may be 0.011 or more and 0.023 or less. 1st " is the ratio of the number of Ni atoms to the total number of atoms of all elements contained in the main phase (hereinafter referred to as "(Ni / all elements) main ". It is preferable that it is larger than .

[0047] These composite oxides may be crystalline, amorphous, or a mixture thereof.

[0048] (2.3. Identification of the first phase) In the dielectric composition, a known method can be used to identify the main phase and the first phase.

[0049] In this embodiment, first, a main phase and a grain boundary can be distinguished based on differences in contrast in a cross-sectional image of a dielectric composition obtained by a scanning transmission electron microscope (STEM) or a scanning electron microscope (SEM). Next, a first phase at a grain boundary can be identified by mapping analysis using energy dispersive X-ray spectroscopy (EDS) or wavelength dispersive X-ray spectroscopy (WDS). For example, a mapping analysis is performed on a cross-section of a dielectric composition 2 as shown in FIG. 4 to obtain a mapping image of each element constituting the dielectric composition. In the mapping image, the atomic ratio of a predetermined element in a region corresponding to each pixel can be identified based on the brightness of each pixel. For example, in the mapping image, a region where the atomic ratios of both Si and Ni are high can be determined to be the first phase. Specifically, in the mapping image of the dielectric composition, a region where the intensity of Ni is higher than that of the surrounding area and the intensity of Si is higher than that of the surrounding area is determined to be the first phase. Note that the main phase and the first phase may be identified separately by mapping analysis. From the viewpoint of observing the first phase accurately, the above analysis was carried out within 16 μm on the cross section of the dielectric composition. 2 It is preferable to carry out the process for an area of ​​.

[0050] In the above analysis, 1 μm of the first phase identified 2 The number of first phases may be counted visually in the observed image or calculated by image processing. Furthermore, the average value of the area-equivalent circle diameter can be calculated by calculating the area of ​​the identified first phase in the above analysis. The area of ​​the first phase can be calculated by image processing.

[0051] The first phase mentioned above is "(Ni / all elements) 1st " can be calculated by performing point analysis by EDS or WDS on the first phase identified as described above. Specifically, point analysis is performed on all constituent elements in each of three or more first phases, and the average value of the atomic number ratios of the measured constituent elements is taken as the atomic number ratio of the constituent elements of the first phase. From the obtained atomic number ratios, "(Ni / all elements)1st " is calculated. Note that the above-mentioned "(Ni / all elements) main " (Ni / All elements) 1st " can be calculated by performing point analysis on the target region (main phase) in the same way as "(Ni / all elements) whole " can be calculated by scanning the beam over the entire target area (dielectric composition) and performing a quantitative analysis of the composition.

[0052] (2.4. Inner and outer layer regions) The inner dielectric layer constituting the inner layer region and the outer dielectric layer constituting the outer layer region may be made of the same dielectric composition or different dielectric compositions, as long as they are made of the above-mentioned dielectric composition.

[0053] In this embodiment, the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition constituting the outer dielectric layer (hereinafter referred to as "(Ni / all elements)") outer whole ") is the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition that constitutes the inner dielectric layer (hereinafter referred to as "(Ni / all elements) inner whole It is preferable that the value is smaller than (Ni / all elements). outer whole / (Ni / all elements) inner whole is preferably 0.2 or less, more preferably 0.16 or less (Ni / all elements). outer whole (Ni / all elements) inner whole In order to make the amount of Ni smaller than the above, for example, the amount of Ni contained in the raw material of the dielectric composition constituting the outer dielectric layer may be made smaller than the amount of Ni contained in the raw material of the dielectric composition constituting the inner dielectric layer.

[0054] Cracks in the outer layer region tend to occur at the interface between the dielectric layer and the internal electrode layer located at the outermost position in the inner layer region, and progress through the outer layer region to the surface of the element body. On the other hand, when Ni is contained in the dielectric composition, the main component particles tend to grow, and cracks tend to progress as the particle size increases. Therefore, (Ni / all elements) outer whole (Ni / all elements) inner whole By making it smaller, grain growth in the outer layer region is suppressed, and even if cracks occur, they are less likely to progress.

[0055] In addition, in the inner layer region, the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition located near the interface between the dielectric layer and the internal electrode layer (hereinafter referred to as "(Ni / all elements) inner interface whole ") is the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition located at the midpoint between adjacent internal electrode layers in the lamination direction (hereinafter referred to as "(Ni / all elements) inner interlayer whole It is preferable that the number of layers is larger than the number of layers of the dielectric layer. This can increase the bonding strength between the dielectric layer and the internal electrode layer.

[0056] (3. Manufacturing method of multilayer capacitor) Next, an example of a method for manufacturing the multilayer capacitor 1 shown in FIG. 1 will be described below.

[0057] The multilayer capacitor 1 according to this embodiment can be manufactured by a known method similar to that used for conventional multilayer capacitors. An example of such a known method is a method in which a green chip is produced using a paste containing raw materials for a dielectric composition, and then fired to manufacture a multilayer capacitor. The manufacturing method will now be described in detail.

[0058] First, starting materials for the dielectric composition are prepared. As the starting materials, oxides of the elements contained in the dielectric composition can be used. Also, various compounds that become components constituting the dielectric composition upon firing can be used. Examples of various compounds include carbonates, oxalates, nitrates, hydroxides, and organometallic compounds. These starting materials may be in the form of solids or liquids. In this embodiment, the starting materials are preferably in the form of powders. When the starting materials are powders, the average particle size can be, for example, within the range of 0.1 to 5 μm.

[0059] In this embodiment, it is preferable to obtain the raw materials for forming the main phase and the raw materials for forming the first phase using the above starting materials.

[0060] The raw material for forming the main phase can be obtained as a calcined powder for the main phase, for example, as follows. a B b C4O 15+ The starting materials are weighed in predetermined proportions so as to obtain a composite oxide composition represented by α, and then wet-mixed for a predetermined time using a ball mill or the like to obtain a mixed powder. The obtained mixed powder is dried and then heat-treated in air at a temperature in the range of 700 to 1300°C to obtain a calcined powder for the main phase. After the heat treatment, wet-pulverization may be performed for a predetermined time using a ball mill or the like to adjust the particle size of the calcined powder for the main phase. This calcined powder for the main phase is a powder represented by the general formula A a B b C4O 15+ It is a powder of a composite oxide represented by α.

[0061] The raw materials for forming the first phase can be obtained as a calcined powder for the first phase, for example, as follows. For the calcined powder for the first phase, a raw material containing at least Ni and a raw material containing Si are used, and as necessary, a raw material containing Ba, a raw material containing Mg, a raw material containing Sr, and a raw material containing Ca are used. First, the starting materials are weighed in a predetermined ratio so as to obtain the composite oxide containing at least Ni and Si, and then wet-mixed for a predetermined time using a ball mill or the like to obtain a mixed powder. The obtained mixed powder is dried and then heat-treated in air at a temperature in the range of 700 to 1200°C to obtain the calcined powder for the first phase. After the heat treatment, the particle size of the calcined powder for the first phase may be adjusted by wet-pulverizing for a predetermined time using a ball mill or the like. This calcined powder for the first phase is a powder of a composite oxide (Ni-Si-O, (Ba, Mg, Sr, Ca)-Ni-Si-O). (Ni / all elements) 1st " can be controlled by changing the proportion of raw materials containing Ni.

[0062] Next, a paste for producing a green chip is prepared. The obtained calcined powder for the main phase and the calcined powder for the first phase are mixed in a predetermined ratio to obtain a raw material powder for the dielectric composition. In this manner, in this embodiment, the composite oxide that constitutes the first phase is formed in advance, and then mixed with the composite oxide that constitutes the main phase, followed by firing as described below to obtain the dielectric composition.

[0063] In this embodiment, the amount of the calcined powder for the first phase added to 100 parts by mass of the calcined powder for the main phase is preferably 0.1 parts by mass or more and 5 parts by mass or less. By adjusting the amount of the calcined powder for the first phase added and the particle size of the calcined powder for the first phase, it is possible to obtain a particle size of 1 μm or less. 2 The number of first phases present in the sintered body and the average value of the equivalent circle diameter of the first phases can be controlled.

[0064] A binder and a solvent are further added to the obtained raw material powder of the dielectric composition, and the mixture is kneaded to form a paint to prepare a dielectric layer paste. When the inner dielectric layer and the outer dielectric layer are composed of different dielectric compositions, the raw material powders of the dielectric compositions are prepared by adjusting the composition of the calcined powder for the main phase and the composition of the calcined powder for the first phase, and the like, and the paste for the inner dielectric layer and the paste for the outer dielectric layer are then prepared. Known binders and solvents may be used. The dielectric layer paste may also contain additives such as plasticizers and dispersants, as necessary.

[0065] The internal electrode layer paste is obtained by kneading the above-mentioned raw materials of the conductive material, a binder, and a solvent. Known binders and solvents may be used. The internal electrode layer paste may contain additives such as co-materials and plasticizers as necessary.

[0066] The external electrode paste can be prepared in the same manner as the internal electrode layer paste.

[0067] Using each of the obtained pastes, green sheets and internal electrode patterns are formed, which are then laminated and cut to obtain green chips.

[0068] The obtained green chip is subjected to a binder removal treatment as needed. The binder removal treatment conditions may be known conditions, and for example, the holding temperature is preferably 200 to 350°C.

[0069] After the binder removal process, the green chip is fired to obtain the element body. In this embodiment, since the composite oxide constituting the main phase has the above-mentioned composition, firing can be performed in a reducing atmosphere (reducing firing). Other firing conditions may be known conditions, and for example, the holding temperature is preferably 1200 to 1450°C.

[0070] After firing, the obtained element body is subjected to a reoxidation treatment (annealing) as necessary. The annealing conditions may be well-known conditions, and for example, it is preferable that the oxygen partial pressure during annealing is higher than that during firing, and that the holding temperature is 1150°C or less.

[0071] The dielectric layer of the element body obtained as described above is a layer of the above-mentioned dielectric composition. The end faces of this element body are polished, and an external electrode paste is applied and baked to form the external electrodes 4. Then, if necessary, a coating layer is formed on the surface of the external electrodes 4 by plating or the like.

[0072] In this manner, a multilayer capacitor as an example of an electronic component according to this embodiment is manufactured.

[0073] (4. Summary of this embodiment) In this embodiment, the dielectric layer provided in the electronic component having an electrode mainly composed of nickel is a compound represented by the general formula A a B b C4O 15+ The dielectric composition is composed of a composite oxide represented by formula (α) and nickel. This dielectric composition has a main phase composed of the composite oxide and grain boundaries existing between the main phases. The grain boundaries contain at least a first phase composed of a composite oxide containing at least nickel and silicon (Ni-Si-O, (Ba, Mg, Sr, Ca)-Ni-Si-O).

[0074] The inclusion of nickel in the dielectric composition makes it easier for the nickel in the dielectric composition to bond with the nickel contained in the electrode. Such bonding occurs at the interface between the dielectric composition and the electrode, strengthening the bond between the dielectric composition and the electrode. As a result, cracks, which tend to occur at the interface, are less likely to occur. Furthermore, even if cracks do occur, their progression is suppressed by the first phase containing nickel and silicon.

[0075] Therefore, since the dielectric composition contains nickel and the first phase is present, cracks are less likely to occur, and even if cracks do occur, their progression can be suppressed, thereby ensuring sufficient reliability of the electronic component.

[0076] Moreover, general formula A a B b C4O 15+ In the composite oxide represented by α, by making "a" 3.05 or more and "b" 1.01 or more, the composite oxide is given reduction resistance. As a result, even when an electrode pattern mainly composed of nickel and the raw materials of the dielectric composition are subjected to reduction firing, the resistivity of the resulting dielectric composition can be maintained high (the dielectric composition can be prevented from becoming a semiconductor or a conductor), and the dielectric properties required for an insulator can be fully exhibited.

[0077] (5. Modifications) In the above-described embodiment, the case where the electronic component according to the present embodiment is a multilayer capacitor has been described. However, the electronic component according to the present embodiment may be an electronic component other than a multilayer capacitor as long as it has the dielectric composition described above.

[0078] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and may be modified in various ways within the scope of the present invention. [Example]

[0079] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0080] (Experiment 1) First, powders of barium carbonate (BaCO3), zirconium oxide (ZrO2), niobium oxide (Nb2O5), silicon oxide (SiO2), and nickel oxide (NiO) were prepared as starting materials for the dielectric composition.

[0081] (Sample No. 1) The prepared starting materials were weighed so that the molar ratio of BaCO3, ZrO2, Nb2O5, and NiO was BaCO3:ZrO2:Nb2O5:NiO = 3.1:1.1:2:0.2. The weighed powders were wet-mixed in a ball mill for 16 hours using ion-exchanged water as a dispersion medium, and the mixture was dried to obtain a mixed powder. The obtained mixed powder was then heat-treated in air at a holding temperature of 900°C for 2 hours to obtain a calcined powder. The obtained calcined powder mainly constitutes the main phase (complex oxide) in the dielectric composition. This calcined powder was used as the main phase calcined powder.

[0082] The prepared starting materials were weighed so that the molar ratio of BaCO3, MgO, NiO, and SiO2 was BaCO3:MgO:NiO:SiO2 = 1:2:0.2:2. The weighed powders were wet-mixed in a ball mill using ion-exchanged water as a dispersant for 16 hours, and the mixture was dried to obtain a mixed powder. The resulting mixed powder was then heat-treated in air at 1000°C for 2 hours. The heat-treated powder was wet-ground in a ball mill using ion-exchanged water as a dispersant for 16 hours, and the ground product was dried to obtain a calcined powder. The resulting calcined powder was a composite oxide powder containing Ba, Mg, Ni, and Si (Ba-Mg-Ni-Si-O powder), and mainly constituted a first phase different from the main phase in the sintered dielectric composition. This calcined powder was designated as the first-phase calcined powder.

[0083] The calcined powder for the main phase and the calcined powder for the first phase obtained above were mixed to obtain a raw material powder for the dielectric composition. The amount of the calcined powder for the first phase added was 2 parts by mass per 100 parts by mass of the calcined powder for the main phase.

[0084] The obtained raw material powder of the dielectric composition was mixed with a binder and a solvent to prepare a paste. The obtained paste was used to form a green sheet that would become the dielectric layer, and a paste containing nickel (Ni) powder as a conductive material was printed on top of it to form an internal electrode pattern that would become the internal electrode layer. These were stacked to obtain a green body for the inner layer region. Meanwhile, the obtained paste was used to form a green sheet, and multiple green sheets thus formed were stacked to obtain a green body for the outer layer region. The green body for the inner layer region was sandwiched between green bodies for the outer layer region in the stacking direction and pressure-bonded to form a green laminate. Furthermore, the green laminate was cut into a predetermined shape to obtain a green chip.

[0085] The obtained green chip was subjected to a binder removal process, fired in a reducing atmosphere, and then annealed to obtain a sintered body (element body) in which internal electrode layers and dielectric layers formed of layers of dielectric composition were laminated and integrated. The firing conditions were a temperature rise rate of 200°C / h, a holding temperature of 1320°C, and a holding time of 2 hours. The atmospheric gas was a mixed gas of nitrogen and hydrogen (hydrogen concentration 3%) humidified to a dew point of 20°C. The annealing conditions were a holding temperature of 1050°C, and a holding time of 2 hours. The atmospheric gas was nitrogen gas humidified to a dew point of 20°C.

[0086] After polishing the obtained element body, an electrode paste containing Cu powder, binder, and solvent was applied to the end faces where the internal electrode layers were exposed, and after drying, sintering was performed to form external electrodes, thereby obtaining a multilayer capacitor sample. In the multilayer capacitor sample, the thickness of the dielectric layer in the internal layer region was 5 μm, the thickness of the internal electrode layer was 1.2 μm, the number of dielectric layers sandwiched between the internal electrode layers was four, and the thickness of the outer layer region was 200 μm. The obtained multilayer capacitor sample was evaluated for the presence or absence of nickel and the first phase in the dielectric composition.

[0087] A portion of the cross section of the dielectric layer near the center of the obtained multilayer capacitor was thinned using a focused ion beam (FIB) processing device to prepare a sample. The prepared sample was observed using a scanning transmission electron microscope (STEM). The observation field was 4 μm × 4 μm, and the field area was 16 μm. 2 The main phase was distinguished from other regions by the contrast difference in the STEM dark-field image in the observation field. Next, energy dispersive X-ray spectroscopy (EDS) was used to obtain mapping images of barium (Ba), zirconium (Zr), niobium (Nb), magnesium (Mg), silicon (Si), and nickel (Ni) in the observation field.

[0088] From each mapping image, the region other than the main phase where Ni and Si were observed in large amounts was determined to be a phase containing Ni, Si, and O (first phase). In sample number 1, at least the main phase and the first phase were observed. The first phase was a composite oxide containing Ba, Mg, Ni, and Si.

[0089] In addition, quantitative analysis of the composition was performed by beam scanning the entire target area (dielectric composition) in the above observation field using EDS with STEM. From the obtained point analysis results, the atomic ratio of all elements contained in the dielectric composition was obtained, and the formula "(Ni / all elements)" was calculated. whole The results are shown in Table 1.

[0090] Furthermore, point analysis was performed on the five first phases identified in the above observation field using EDS with STEM. From the obtained point analysis results, the atomic ratio of all elements contained in the first phase was obtained, and the formula "(Ni / all elements)" was calculated. 1st The results are shown in Table 1.

[0091] The obtained multilayer capacitor samples were subjected to the following characteristic evaluations.

[0092] (crack rate) A pressure cooker test (PCT) was conducted to evaluate the resistance of multilayer capacitors to cracking. In the PCT, multilayer capacitor samples were placed in a pressure cooker and exposed to an environment of 121°C and 95% relative humidity for 24 hours. After the test, the appearance of the multilayer capacitor samples was observed using a stereomicroscope to evaluate whether or not cracks had occurred in the multilayer capacitor. The PCT was conducted on 20 multilayer capacitor samples, and samples with cracks occurring in one or fewer of the 20 were judged to be good. It was more preferable if no cracks occurred in any of the 20 samples. The results are shown in Table 1.

[0093] (Sample No. 2) A multilayer capacitor sample was fabricated in the same manner as sample No. 1, except that NiO was not added as a starting material to the calcined powder for the main phase. The fabricated multilayer capacitor sample was evaluated in the same manner as sample No. 1. The results are shown in Table 1.

[0094] (Sample No. 3) A multilayer capacitor sample was fabricated in the same manner as sample No. 1, except that the amount of NiO used as a starting material in the calcined powder for the main phase was reduced. The fabricated multilayer capacitor sample was evaluated in the same manner as sample No. 1. The results are shown in Table 1.

[0095] (Sample No. 4) Except for varying the amount of NiO used as a starting material in the calcined powder for the first phase, multilayer capacitor samples were fabricated in the same manner as sample number 1. The fabricated multilayer capacitor samples were evaluated in the same manner as sample number 1. The results are shown in Table 1.

[0096] (Sample No. 5) Except for varying the amount of NiO used as a starting material in the calcined powder for the first phase, multilayer capacitor samples were fabricated in the same manner as sample number 1. The fabricated multilayer capacitor samples were evaluated in the same manner as sample number 1. The results are shown in Table 1.

[0097] (Sample No. 6) Multilayer capacitor samples were fabricated using the same method as for Sample 1, except that the main phase calcined powder did not contain NiO as a starting material, nor did it contain the first phase calcined powder. Instead, 2 parts by mass of Ba-Mg-Si-O powder was added per 100 parts by mass of the main phase calcined powder. The Ba-Mg-Si-O powder was fabricated using the same method as for the first phase calcined powder of Sample 1, except that the starting materials were weighed so that the molar ratio of BaCO3, MgO, and SiO2 was BaCO3:MgO:SiO2 = 1:2:2, and the heat treatment conditions were a holding temperature of 1000°C and a holding time of 2 hours. The fabricated multilayer capacitor samples were evaluated using the same method as for Sample 1. The results are shown in Table 1. No first phase was observed in Sample 6.

[0098] (Sample No. 7) A multilayer capacitor sample was fabricated in the same manner as sample No. 1, except that the calcined powder for the first phase was not blended and 2 parts by mass of the Ba-Mg-Si-O powder used in sample No. 6 was added to 100 parts by mass of the calcined powder for the main phase. The fabricated multilayer capacitor sample was evaluated in the same manner as sample No. 1. The results are shown in Table 1.

[0099] [Table 1]

[0100] From Table 1, it was confirmed that when the dielectric composition contains nickel and the first phase is present, the crack rate is good.

[0101] (Experiment 2) For sample numbers 11 to 14, multilayer capacitor samples were prepared in the same manner as sample number 1, except that the amount of first phase powder added relative to 100 parts by mass of main phase calcined powder was changed.

[0102] In samples 1 and 11 to 14, the first phase was identified using the same method as in Experiment 1. 2The number of first phases in the specimen was calculated. The crack rate was evaluated using the same method as in Experiment 1. The results are shown in Table 2.

[0103] [Table 2]

[0104] From Table 2, 1 μm 2 It was confirmed that when the number of the first phases in the sample was within the above-mentioned range, the crack rate was good.

[0105] (Experiment 3) For sample numbers 21 to 24, multilayer capacitor samples were prepared using the same method as sample number 1, except that the conditions for pulverizing the heat-treated calcined powder for the first phase were changed. For sample numbers 1 and 21 to 24, the first phase was identified using the same method as in Experiment 1, and the area of ​​the first phase was calculated using image processing. From the calculated area, the average value of the equivalent circle diameter was calculated. The crack rate was also evaluated using the same method as in Experiment 1. The results are shown in Table 3.

[0106] [Table 3]

[0107] From Table 3, it was confirmed that when the average value of the area-equivalent circle diameter of the first phase is within the above-mentioned range, the crack rate is good.

[0108] (Experiment 4) For sample numbers 31 to 33, the proportion of NiO was changed in the raw powder of the dielectric composition for forming the outer layer region, and the green body for the outer layer region was obtained by the same method as for sample number 1. For sample numbers 31 to 33, quantitative analysis of the composition was performed on the dielectric composition located near the center of the inner layer region by beam scanning the entire target region (dielectric composition) using the same method as in experiment 1, and the "(Ni / all elements)" of the inner layer region was calculated. inner whole" was calculated. In addition, for the dielectric composition located near the center of the outer layer region, a quantitative analysis of the composition was performed by beam scanning the entire target region (dielectric composition) using the same method as in Experiment 1, and the "(Ni / all elements)" of the outer layer region was calculated. outer whole " was calculated. The "(Ni / all elements)" of the inner layer region was calculated. inner whole " and "(Ni / all elements)" in the outer layer region outer whole " and "(Ni / all elements)" in the inner layer region. inner whole " in the outer layer region (Ni / all elements) outer whole The crack rate was evaluated using the same method as in Experiment 1. The results are shown in Table 4.

[0109] [Table 4]

[0110] From Table 4, the inner layer region (Ni / all elements) inner whole " in the outer layer region (Ni / all elements) outer whole It was confirmed that when " is within the above range, the crack rate is good.

[0111] (Experiment 5) For sample numbers 41 and 42, multilayer capacitor samples were prepared by the same method as for sample number 1, except that barium titanate (sample number 41) and calcium zirconate (sample number 42) were used as the calcined powder for the main phase. For sample numbers 41 and 42, the first phase was identified by the same method as in experiment 1. Both samples contained the first phase.

[0112] Next, for samples 1, 41, and 42, the capacitance was measured using a digital LCR meter (Hewlett-Packard, 4284A) at room temperature of 25°C, a frequency of 1 kHz, and an input signal level (measurement voltage) of 1.0 Vrms while applying a DC bias with a field strength of 15 V / μm. The relative dielectric constant when the DC bias was applied was calculated from the measured capacitance, the effective electrode area, the inter-electrode distance, and the dielectric constant of vacuum. The results are shown in Table 5.

[0113] [Table 5]

[0114] From Table 5, it was confirmed that when the main phase is a composite oxide having a perovskite structure of barium titanate and calcium zirconate, the relative dielectric constant is low when a DC bias is applied. [Explanation of symbols]

[0115] 1... Multilayer capacitor 10... Element body 11...Inner layer area 12...Outer layer area 2... Dielectric layer (dielectric composition) 20…Main phase 41...First Phase 3… Internal electrode layer 4... External electrode

Claims

1. An electronic component comprising a dielectric layer in which a dielectric composition is formed in a layered form, and an electrode layer containing nickel as a main component, The dielectric composition is represented by the general formula A a B b C 4 O 15+ a, wherein A represents an element group containing at least barium, B represents an element group containing at least zirconium, C represents an element group containing at least niobium, a is 3.05 or more, and b is 1.01 or more, and the composite oxide as a main component and nickel are contained, The dielectric composition has a main phase composed of the complex oxide and a first phase that contains a complex oxide having nickel, silicon, and oxygen and is different from the main phase.

2. 2. The electronic component according to claim 1, wherein in the dielectric composition, the ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition is 0.005 or more and 0.02 or less.

3. 3. The electronic component according to claim 1, wherein in the first phase, a ratio of the number of nickel atoms to the total number of atoms of all elements contained in the first phase is 0.01 or more and 0.03 or less.

4. In the cross section of the dielectric composition, 2 3. The electronic component according to claim 1, wherein the number of the first phases present therein is 0.05 to 1.

5. 3. The electronic component according to claim 1, wherein the average equivalent circle diameter of the first phase is in the range of 0.05 μm to 0.5 μm.

6. The electronic component includes an inner layer region in which the dielectric layers and the internal electrode layers are alternately stacked; an outer layer region that is arranged on at least one end surface of the inner layer region in the lamination direction of the dielectric layers and the internal electrode layers and is made of the dielectric composition, 3. The electronic component according to claim 1, wherein a ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition located in the outer layer region is smaller than a ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition located in the inner layer region.

7. 7. The electronic component according to claim 6, wherein in the inner layer region, a ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition located in the vicinity of an interface between the dielectric layer and the internal electrode layer is greater than a ratio of the number of nickel atoms to the total number of atoms of all elements contained in the dielectric composition located at a midpoint between adjacent internal electrode layers in the lamination direction.

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