JP2018020931A - Dielectric composition and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric composition that has high resistivity in a high temperature atmosphere of 200°C fitted for onboard equipment and power devices using SiC or GaN semiconductors, and shows a small change rate of resistivity from room temperature to 200°C, and an electronic component prepared therewith.SOLUTION: A dielectric composition contains, as a main component, a tungsten bronze type complex oxide represented by chemical formula (KNa) SrNbO(where, 0≤x≤0.4), the dielectric composition containing accessory components of MgO, BaO, BO, SiO, and PO, with a total content of the accessory components being 2.5 mol-20.0 mol relative to the main component 100 mol.SELECTED DRAWING: Figure 1

Description

  In particular, the present invention relates to a dielectric composition suitable for use in a high temperature environment such as in-vehicle use, and an electronic component using the dielectric composition as a dielectric layer.

  Multilayer ceramic capacitors are mounted on many electronic devices because of their high reliability and low cost. Specific electronic devices include information terminals such as mobile phones, home appliances, and automobile electrical components. Among them, multilayer ceramic capacitors used for automotive use are required to have a higher temperature range than multilayer ceramic capacitors used in home appliances and information terminals, and high insulation is required to maintain their functions. Sexuality is required.

  Furthermore, the multilayer ceramic capacitor for surge voltage removal mounted on an inverter circuit using a power semiconductor such as SiC or GaN, which is considered to be used in a high temperature range of 150 ° C. or higher, has a wide range from room temperature to at least 200 ° C. High insulation is required at temperature.

Patent Document 1 discloses a chemical formula (1- (1)) which is a dielectric ceramic composition that exhibits a sufficient dielectric constant and can obtain a stable capacitance temperature characteristic and a high resistivity ρ even at a high temperature of about 175 ° C. _{a) (K 1-x Na} x) (Sr 1-y-z Ba y Ca z) 2 Nb 5 O 15 -a (Ba 1-b Ca b) a tungsten bronze structure compound represented by TiO ₃ with perovskite A technology relating to a multilayer ceramic capacitor using a dielectric ceramic composition containing a mixed crystal system with a structural compound as a main component and containing 0.1 to 40 mol parts of subcomponents with respect to 100 mol parts of the main component. It is disclosed.

Patent Document 2 discloses a dielectric containing, as a main component, a tungsten bronze-type composite oxide represented by a chemical formula (K _1-x Na _x ) Sr ₂ Nb ₅ O ₁₅ (where 0 ≦ x <0.2). A dielectric ceramic composition having a high resistivity at room temperature by containing 0.05 to 20 mol parts of rare earth elements and 0.05 to 40 mol parts of Mn, V, Li, etc. as subcomponents in the body ceramic composition Technology about things is disclosed.

In Patent Document 3, the chemical formula [(Ba _1-xy Ca _x Sr _y ) O] _m · (Ti _1-z Zr _z ) O ₂ is a main component, and P ₂ O ₅ is 0.005 as a subcomponent. Disclosed is a technology for improving the high-temperature load life by acting as a barrier layer that prevents migration of Ni ions during a high-temperature load test by containing ˜0.5% by weight (about 0.5 mol% in terms of mol%). Has been.

WO2008 / 155945 WO2008 / 102608 publication Japanese Patent Laid-Open No. 2000-124058

However, although the said patent document 1 has favorable insulation in a high temperature range (175 degreeC), it does not mention the rate of change of specific resistance. Although the said patent document 2 also contains various subcomponents, insulation at room temperature is favorable, but is not mentioned about the specific resistance in a high temperature range, for example, 200 degreeC. In addition, Patent Document 3 has a high high-temperature load life by containing P ₂ O ₅ in a perovskite-type barium titanate-based material, but it has a specific resistance at room temperature or 200 ° C. and changes thereof. The rate has not been considered.

  The present invention has been made in view of the above problems, and has a high specific resistance in a high temperature atmosphere of 200 ° C. suitable for in-vehicle use and power devices using SiC or GaN-based semiconductors. It is to provide a dielectric composition having a small rate of change in specific resistance at ° C. and an electronic component using the dielectric composition.

To achieve the above object, the dielectric composition of the present invention has the formula _{(K 1-x Na x)} Sr 2 Nb 5 O 15 ( where, 0 ≦ x ≦ 0.40) tungsten bronze type compound represented by the In the dielectric composition mainly composed of oxide, MgO, BaO, B ₂ O ₃ , SiO ₂ , P ₂ O ₅ are included as the first subcomponent, and the total content of the subcomponents is 100 mol of the main component On the other hand, it is characterized by being 2.5 mol to 20.0 mol.

  When the dielectric composition has the above-described characteristics, it is possible to provide a dielectric composition having good insulating properties suitable for being used in a wide range from room temperature to 200 ° C. The good insulation means a high specific resistance at 200 ° C. and a small change rate of specific resistance in a wide range from room temperature to 200 ° C.

  Furthermore, by using a dielectric layer made of the dielectric composition, it can be used in in-vehicle applications that require use in a low temperature range of −55 ° C. to a temperature of about 150 ° C., or even a higher temperature of about 200 ° C. It is possible to provide a snubber capacitor for a power device using a required SiC or GaN-based semiconductor, a capacitor used for noise removal in an automobile engine room, and the like.

  The present invention provides a dielectric composition having a high specific resistance and a small change rate in specific resistance from room temperature to 200 ° C. in a high temperature atmosphere of 200 ° C. for use in vehicles and power devices using SiC or GaN-based semiconductors. Things and electronic parts using them can be provided.

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.

  First, a multilayer ceramic capacitor, which is a main use of the dielectric composition of the present invention, will be described. FIG. 1 shows a cross-sectional view of a general multilayer ceramic capacitor.

  The multilayer ceramic capacitor 1 has a capacitor element body 10 having a configuration in which dielectric layers 2 and internal electrode layers 3 are alternately stacked. At both ends of the capacitor element body 10, a pair of external electrodes 4 are formed which are electrically connected to the internal electrode layers 3 arranged alternately in the capacitor element body 10. The shape of the capacitor element body 10 is not particularly limited, but is usually a rectangular parallelepiped shape. Moreover, there is no restriction | limiting in particular also in the dimension, What is necessary is just to set it as a suitable dimension according to a use.

  The internal electrode layers 3 are laminated so that the end faces are alternately exposed on the surfaces of the two opposite ends of the capacitor element body 10. The pair of external electrodes 4 are formed at both ends of the capacitor element body 10 and are connected to the exposed end surfaces of the alternately arranged internal electrode layers 3 to constitute a capacitor circuit.

  The thickness of the dielectric layer 2 is not particularly limited, but is preferably 100 μm or less per layer, more preferably 30 μm or less. Although the minimum of thickness is not specifically limited, For example, it is about 0.5 micrometer. According to the dielectric composition of the present invention, the multilayer ceramic capacitor 1 having good insulating properties can be formed even when the interlayer thickness is 0.5 μm to 30 μm.

  The number of laminated dielectric layers 2 is not particularly limited, but is preferably 20 or more, more preferably 50 or more.

  The conductive material contained in the internal electrode layer 3 is not particularly limited, but Ni, Ni alloy, Cu or Cu-based alloy is preferable. In addition, in Ni, Ni-type alloy, Cu, or Cu-type alloy, various trace components, such as P, may be contained about 0.1 mass% or less. The internal electrode layer 3 may be formed using a commercially available electrode paste. What is necessary is just to determine the thickness of the internal electrode layer 3 suitably according to a use etc.

  More preferably, the conductive material contained in the internal electrode layer 3 is Ni or a Ni-based alloy because the constituent material of the dielectric layer 2 has reduction resistance. It is more preferable that this Ni or Ni-based alloy is a main component and it contains one or more subcomponents selected from Al, Si, Li, Cr, and Fe.

  Ni or Ni-based alloy which is the main component of the internal electrode layer 3 contains one or more subcomponents selected from Al, Si, Li, Cr and Fe, so that Ni reacts with oxygen in the atmosphere. Before becoming NiO, the subcomponent reacts with oxygen to form a subcomponent oxide film on the surface of Ni. Thereby, since oxygen in the outside air cannot react with Ni unless it passes through the oxide film of the subcomponent, Ni is hardly oxidized. Thereby, even if it is continuously used at a high temperature of 200 ° C., deterioration of continuity and conductivity due to oxidation of the internal electrode layer containing Ni as a main component hardly occurs.

  The conductive material contained in the external electrode 4 is not particularly limited, but in the present invention, inexpensive Ni, Cu, highly heat-resistant Au, Ag, Pd, and alloys thereof can be used. The thickness of the external electrode 4 may be determined as appropriate according to the application and the like, but is usually preferably about 10 to 50 μm.

  Next, the dielectric composition according to this embodiment will be described in detail.

The dielectric composition according to the present embodiment is mainly composed of a tungsten bronze complex oxide represented by the chemical formula (K _1-x Na _x ) Sr ₂ Nb ₅ O ₁₅ (where 0 ≦ x ≦ 0.40). In the dielectric composition, MgO, BaO, B ₂ O ₃ , SiO ₂ , P ₂ O ₅ are included as the first subcomponent, and the total content of the subcomponents is 2. It is characterized by being 5 mol to 20.0 mol.

  When the dielectric composition has the above-described characteristics, it is possible to provide a dielectric composition having good insulating properties suitable for being used in a wide range from room temperature to 200 ° C. The factors for obtaining such effects are shown below.

The inventors have disclosed a dielectric composition mainly composed of a tungsten bronze-type composite oxide represented by the chemical formula (K _1-x Na _x ) Sr ₂ Nb ₅ O ₁₅ (where 0 ≦ x ≦ 0.40). Main cause of decrease in specific resistance from room temperature to a high temperature range of about 200 ° C. by containing a predetermined amount of the first subcomponent consisting of MgO, BaO, B ₂ O ₃ , SiO ₂ , and P ₂ O ₅ It has been found that an effect of suppressing the increase and movement of electrons, which are considered to be majority carriers, can be obtained. As a result, it is considered that it has become possible to maintain a high insulating property in a wide temperature range from room temperature to about 200 ° C., which has been difficult to realize until now.

In the chemical formula, K in (K _1-x Na _x ) Sr ₂ Nb ₅ O ₁₅ is substituted with Na. The substitution amount x is 0 ≦ x ≦ 0.40. When the substitution amount x exceeds 0.40, the first subcomponent consisting of MgO, BaO, B ₂ O ₃ , SiO ₂ , P ₂ O ₅ , which is a feature of the dielectric composition according to this embodiment. Even if it contains, the effect | action which suppresses the increase of the electron which is a majority carrier considered to be the main cause of the fall of a specific resistance, and its movement is not acquired, As a result, the specific resistance in 200 degreeC falls, and it is 200 from room temperature. The rate of change in specific resistance at ° C will deteriorate.

In addition, MgO, BaO, B ₂ O ₃ , SiO ₂ , P ₂ O ₅ is included as the first subcomponent, and the total content of the first subcomponent is from 2.5 mol to 100 mol of the main component. 20.0 mol. Thereby, the effect | action which suppresses the increase of the electron which is the majority carrier considered to be the main cause of the fall of a specific resistance, and its movement is acquired, and favorable insulation is obtained as a result. When the total content is less than 2.5 mol or more than 20.0 mol, the increase in electrons or movement of electrons that are majority carriers cannot be suppressed, and the specific resistance at 200 ° C. becomes low. Therefore, the rate of change in specific resistance is deteriorated. In addition, combinations other than the above five types of oxides as subcomponents cannot effectively suppress an increase in electrons that are majority carriers, and the specific resistance at room temperature is lowered.

Desirable embodiments of the present invention, when expressed said first subcomponent and _{aMgO-bBaO-cB 2 O 3} -dSiO 2 -eP 2 O 5, wherein a, b, c, d, the relationship e is a + b + c + d + e = 1.00, 0.50 ≦ a ≦ 0.75, 0.02 ≦ b ≦ 0.15, 0.05 ≦ c ≦ 0.25, 0.05 ≦ d ≦ 0.25, 0.02 ≦ e It is preferable that ≦ 0.15. By setting it as said range, the effect | action which suppresses the increase and movement of the electron which is a majority carrier can be heightened. For this reason, it is possible to further increase the specific resistance at 200 ° C. and further reduce the rate of change in specific resistance from room temperature to 200 ° C.

As the preferred embodiment of the present invention are selected further, as the second _{subcomponent,} from _{La 2 O 3, SnO 2,} Y 2 O 3, Sb 2 O 3, Ta 2 O 5, Nb 2 O 5 It is preferable to contain at least one or more of 0.5 mol to 5.0 mol with respect to 100 mol of the main component. Thereby, it is possible to improve the DC withstand voltage at 200 ° C. as well as good insulation.

The dielectric composition contains a secondary phase containing MgO and P ₂ O _5, and when the total area of the cross section of the dielectric composition is 100%, the area occupied by the secondary phase is: It is preferable that it is 2.0%-15.0%. The secondary phase containing MgO and P ₂ O ₅ has a phosphoric crystal structure of 3MgO · P ₂ O ₅ or (MgO · BaO) -P ₂ O ₅ . In addition, the secondary phase in the dielectric composition is present in the form of particles having an MgO and P ₂ O ₅ content of 90 mol% or more, or a segregation phase present at grain boundaries or triple boundaries of grain boundaries. It is preferable. As a result, by including a predetermined amount of the secondary phase, it is possible to keep the specific resistance change rate small even in a wider temperature range from room temperature to 250 ° C.

  In the case of a multilayer ceramic capacitor sample which is an example of the present embodiment, the above-described area ratio is obtained by performing microsampling using FIB (Focused Ion Beam) to produce a TEM sample of a dielectric layer, and scanning transmission It is calculated | required by performing STEM-EDS (Scanning Transmission Electron Microscopy-Energy Dispersive X-ray Spectrometry) mapping using an electron microscope. The field of view of mapping is 7 μm × 7 μm, and it is preferable to perform mapping of 10 fields or more for each sample. Further, the area ratio can also be obtained by performing element mapping on the polished dielectric layer cross section by EPMA (Elctron Probe Micro Analyzer). The visual field of mapping at that time is 10 μm × 10 μm, and mapping of five or more visual fields is performed for each sample, and the area ratio may be calculated from the obtained element map.

  As described above, since the dielectric composition according to the present embodiment exhibits good characteristics in a high temperature region, it is preferably used in a use temperature range (−55 ° C. to 200 ° C. or 250 ° C.) of a SiC or GaN-based power device. Can be used. Further, it can be suitably used as an electronic component for removing noise in a severe environment such as an engine room of an automobile.

Note that (K _1-x Na _x ) Sr ₂ Nb ₅ O ₁₅ in the above chemical formula has a molar ratio of 1: 2: 5: 15 basically for each K site, Sr site, Nb site, and O site. However, as long as the tungsten bronze structure can be maintained, it may be slightly increased or decreased.

  In addition, the dielectric composition according to the present embodiment may contain minute impurities and third subcomponents as long as the good insulating properties that are the effects of the present invention are not significantly deteriorated. For example, Mn, V, Cr and the like. Accordingly, the content of the main component is not particularly limited, but is, for example, 70 mol% or more and less than 98 mol% with respect to the entire dielectric composition containing the main component.

  Next, a method for manufacturing the dielectric composition according to this embodiment will be described. A known method may be adopted as a method for manufacturing the dielectric composition. For example, a solid phase method or the like in which starting materials such as oxide powder and carbonate are mixed and the obtained mixed powder is heat-treated and synthesized may be employed.

The main component (K _1-x Na _x ) Sr ₂ Nb ₅ O ₁₅ is K ₂ CO ₃ , Na ₂ CO ₃ , SrCO ₃ , Nb ₂ O ₅ powder having an average particle size of 1.0 μm or less as a starting material. Prepare. After weighing to a predetermined ratio, wet mixing is performed for a predetermined time using a ball mill or the like. After drying the mixed powder, heat treatment at 1000 ° C. or lower is performed in the air to obtain a calcined powder of (K _1-x Na _x ) Sr ₂ Nb ₅ O ₁₅ .

As the first subcomponent, MgO, SiO ₂ , BaCO ₃ , B ₂ O ₃ and P ₂ O ₅ powders having an average particle size of 1.0 μm or less are prepared as starting materials. In addition, La ₂ O ₃ , SnO ₂ , Y ₂ O ₃ , Sb ₂ O ₃ , Ta ₂ O ₅ , and Nb ₂ O ₅ powder, which are starting materials for the second subcomponent, are prepared as necessary. After these are weighed to a predetermined ratio, wet mixing is performed for a predetermined time using a ball mill or the like. Then, after drying the mixed powder, heat treatment is performed at 700 ° C. to 800 ° C. for 1 to 5 hours in the air to prepare a calcined powder as a subcomponent. In addition, you may use the said dry mixed powder, without performing heat processing.

Thereafter, the obtained (K _1-x Na _x ) Sr ₂ Nb ₅ O ₁₅ calcined powder and subcomponent calcined powder or subcomponent mixed powder were mixed and pulverized to obtain an average particle size of A mixed powder of 0.5 μm to 2.0 μm is prepared.

  Next, an example of a method for manufacturing the multilayer ceramic capacitor shown in FIG. 1 will be described.

  In the multilayer ceramic capacitor 1 of the present embodiment, a green chip is produced by a normal printing method or a sheet method using a paste as in the case of a conventional multilayer ceramic capacitor, fired, and then fired by applying an external electrode. It is manufactured by doing. Hereinafter, the manufacturing method will be specifically described.

  The mixed powder obtained above is made into a paint to prepare a dielectric layer paste. The dielectric layer paste may be an organic paint obtained by kneading a dielectric mixed powder and an organic vehicle, or may be a water-based paint.

  An organic vehicle is obtained by dissolving a binder in an organic solvent. The binder used for the organic vehicle is not particularly limited, and may be appropriately selected from usual various binders such as ethyl cellulose and polyvinyl butyral. The organic solvent to be used is not particularly limited, and may be appropriately selected from various organic solvents such as terpineol, butyl carbitol, acetone and the like according to a method to be used such as a printing method or a sheet method.

  Further, when the dielectric layer paste is used as a water-based paint, a water-based vehicle in which a water-soluble binder or a dispersant is dissolved in water and a dielectric material may be kneaded. The water-soluble binder used for the water-based vehicle is not particularly limited, and for example, polyvinyl alcohol, cellulose, water-soluble acrylic resin, etc. may be used.

  The internal electrode layer paste is obtained by kneading the above-mentioned organic vehicle with various conductive metals and alloys as described above, or various oxides, organometallic compounds, resinates, etc. that become the above-mentioned conductive materials after firing. Prepare.

  The external electrode paste may be prepared in the same manner as the internal electrode layer paste described above.

  There is no restriction | limiting in particular in content of the organic vehicle in each above-mentioned paste, For example, what is necessary is just about 1 mass%-about 5 mass% for a binder, and about 10 mass%-about 50 mass% for a solvent. Each paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like as necessary. The total content of these is preferably 10% by mass or less.

  When the printing method is used, the dielectric layer paste and the internal electrode layer paste are printed and laminated on a substrate such as PET, cut into a predetermined shape, and then peeled from the substrate to obtain a green chip.

  When the sheet method is used, a dielectric layer paste is used to form a green sheet, the internal electrode layer paste is printed thereon, and these are stacked to form a green chip.

Before firing, the green chip is subjected to binder removal processing. As binder removal conditions, the rate of temperature rise is preferably 5 ° C / hour to 300 ° C / hour, the holding temperature is preferably 180 ° C to 500 ° C, and the temperature holding time is preferably 0.5 hours to 24 hours. The firing atmosphere is air or a reducing atmosphere. Further, in the above-described binder removal process, for example, a wetter or the like may be used to wet the N ₂ gas, mixed gas, or the like. In this case, the water temperature is preferably about 5 ° C to 75 ° C.

  Moreover, the holding temperature at the time of baking becomes like this. Preferably it is 1000 to 1400 degreeC, More preferably, it is 1100 to 1350 degreeC. If the holding temperature is lower than the above range, the densification becomes insufficient. If the holding temperature exceeds the above range, the electrode is interrupted due to abnormal sintering of the internal electrode layer, or the capacitance changes due to diffusion of the internal electrode layer constituting material. The rate tends to increase. On the other hand, if the above range is exceeded, the crystal grains are coarsened and the insulating property may be lowered.

  The rate of temperature rise is preferably 200 ° C./hour to 5000 ° C./hour, more preferably 1000 ° C./hour to 5000 ° C./hour. Further, in order to control the particle size distribution after sintering within a range of 0.5 μm to 5.0 μm, in order to suppress volume diffusion between crystal particles, the temperature holding time is preferably 0.5 hours to 2.0 hours. Time, more preferably 0.5 hour to 1.0 hour, and the cooling rate is preferably 100 ° C./hour to 500 ° C./hour, more preferably 200 ° C./hour to 300 ° C./hour.

Moreover, as an atmosphere for baking, it is preferable to use a humidified mixed gas of N ₂ and H ₂ and to fire at an oxygen partial pressure of 10 ⁻² to 10 ⁻⁹ Pa. More preferably, the oxygen partial pressure is 10 ⁻² to 10 ⁻⁵ Pa. By firing in an atmosphere having a high oxygen partial pressure, an effect of easily precipitating the secondary phase can be obtained. However, when firing in a state where the oxygen partial pressure is high, in the case of an internal electrode layer made of Ni, Ni is oxidized and the conductivity as an electrode is lowered. In this case, by adding one or more subcomponents selected from Al, Si, Li, Cr, and Fe to the conductive material mainly composed of Ni which is a more preferable form of the present embodiment, Ni Thus, even in an atmosphere having a high oxygen partial pressure, it is possible to ensure conductivity as an internal electrode layer.

  After firing, the obtained capacitor element body is annealed as necessary. The annealing conditions may be known conditions. For example, it is preferable that the oxygen partial pressure during the annealing process is higher than the oxygen partial pressure during firing, and the holding temperature is 1000 ° C. or lower.

  Moreover, although the manufacturing method which performs a binder removal process, baking, and an annealing process independently is described above, you may carry out continuously.

  The capacitor element main body obtained as described above is subjected to end face polishing, for example, by barrel polishing or sand blasting, and the external electrode paste is applied and fired to form the external electrode 4. Then, if necessary, a coating layer is formed on the surface of the external electrode 4 by plating or the like.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the embodiment mentioned above at all, and can be variously modified within the range which does not deviate from the summary of this invention.

  EXAMPLES Hereinafter, although the specific Example of this invention is given and this invention is demonstrated further in detail, this invention is not limited to these Examples. In the following, samples marked with * in the table mean that they are outside the scope of this embodiment.

Example 1
First, the main component _{(K 1-x Na x)} Sr 2 Nb 5 O 15 , the average particle size 1.0μm or less of _K 2 _CO 3 as a starting _{material, Na 2 CO 3, SrCO 3} , Nb 2 O 5 The powder was prepared and weighed so as to satisfy the mol ratio described in each sample number in Table 1. Thereafter, wet mixing was performed for 17 hours by a ball mill using ethanol as a dispersion medium. Thereafter, the obtained mixture was dried to obtain a mixed raw material powder. Thereafter, heat treatment was performed in the atmosphere at a holding temperature of 950 ° C. and a holding time of 24 hours to obtain a calcined powder of the main component.

Next, the first subcomponent and the second subcomponent are MgO, SiO ₂ , BaCO ₃ , B ₂ O ₃ , P ₂ O ₅ , La ₂ O ₃ having an average particle size of 1.0 μm or less as a starting material. , SnO ₂ , Y ₂ O ₃ , Sb ₂ O ₃ , Ta ₂ O ₅ , Nb ₂ O ₅ powders were prepared and weighed so as to have the ratios described in each sample number in Table 1. Thereafter, wet mixing was performed for 17 hours by a ball mill using ethanol as a dispersion medium. Thereafter, the mixed powder was dried at 80 ° C. for 24 hours, and then subjected to heat treatment at 750 ° C. to 900 ° C. for 3 hours in the air to prepare a calcined powder as an auxiliary component. Then, the calcined powder of the subcomponent was weighed so that the mixing ratio described in each sample number of Table 1 was obtained with respect to 100 mol of the calcined powder of (K _1-x Na _x ) Sr ₂ Nb ₅ O ₁₅ prepared. , (K _1-x Na _x ) Sr ₂ Nb ₅ O ₁₅ calcined powder and auxiliary calcined powder were mixed and pulverized in a ball mill for 24 hours, and the average particle size was 0.5 μm to 2.0 μm. A mixed calcined powder was produced.

  A basket which is an ordinary well-known dispersion method by adding 700 g of a solvent obtained by mixing a toluene + ethanol solution, a plasticizer and a dispersant at 90: 6: 4 to 1000 g of the mixed calcined powder obtained above. A dielectric layer paste was prepared by dispersing for 2 hours using a mill. The viscosity of these pastes was adjusted to about 200 cps.

As the raw material for the internal electrode layer, Ni having an average particle diameter of 0.2 μm and Al and Si oxides of 0.1 μm or less are prepared, and the total amount of the secondary components Al and Si is 5% by mass with respect to Ni. Weighed so that Thereafter, heat treatment was performed in a humidified mixed gas of N ₂ and H ₂ at 1200 ° C. or higher, and pulverization was performed using a ball mill or the like to prepare a raw material powder having an average particle size of 0.20 μm.

  100 wt% of the raw material powder, 30 wt% of an organic vehicle (8 wt% of ethyl cellulose resin dissolved in 92 wt% of butyl carbitol), and 8 wt% of butyl carbitol are kneaded and formed into a paste by three rolls. An internal electrode layer paste was obtained.

  And the green sheet was formed on the PET film so that the thickness after drying might be set to 12 micrometers using the produced dielectric layer paste. Next, the internal electrode layer was printed in a predetermined pattern using the internal electrode layer paste thereon, and then the sheet was peeled from the PET film to produce a green sheet having the internal electrode layer. Next, a plurality of green sheets having internal electrode layers were laminated and pressure-bonded to form a green laminate, and the green laminate was cut into a predetermined size to obtain a green chip.

  Next, the obtained green chip was subjected to binder removal processing, firing and annealing treatment to obtain a multilayer ceramic sintered body. The conditions for the binder removal treatment, firing and annealing treatment are as follows. Moreover, a wetter was used for humidifying each atmospheric gas.

(Binder removal)
Temperature increase rate: 100 ° C / hour Holding temperature: 400 ° C
Temperature holding time: 8.0 hours Atmospheric gas: Mixed gas of N ₂ and H ₂ humidified (firing)
Temperature rising rate: 1000 ° C./hour holding temperature: 1100 ° C. to 1300 ° C.
Temperature holding time: 1.0 hour Cooling rate: 200 ° C./hour Atmospheric gas: Mixed gas of humidified N ₂ and H ₂ Oxygen partial pressure: 10 ⁻⁶ to 10 ⁻⁹ Pa
(Annealing treatment)
Holding temperature: 1000 ° C
Temperature holding time: 2.0 hours temperature rise, temperature drop rate: 200 ° C./hour Atmosphere gas: humidified N ₂ gas

  As a result of the composition analysis of each sample using ICP emission spectroscopic analysis for each obtained multilayer ceramic sintered body, it was confirmed that it was a value almost equivalent to the dielectric composition described in Table 1. did.

  After polishing the end face of the obtained multilayer ceramic sintered body by sand blasting, an In—Ga eutectic alloy was applied as an external electrode, and sample No. 1 having the same shape as the multilayer ceramic capacitor shown in FIG. 1 to sample no. 59 multilayer ceramic capacitor samples were obtained. The size of the obtained multilayer ceramic capacitor sample was 3.2 mm × 1.6 mm × 1.2 mm, the dielectric layer thickness was 10 μm, the internal electrode layer thickness was 2 μm, and the dielectric sandwiched between the internal electrode layers The number of layers was 50.

  The obtained sample No. 1 to sample no. With respect to 59 multilayer ceramic capacitor samples, the specific resistance at room temperature, the specific resistance at 200 ° C., the rate of change in the specific resistance at that time, and the direct current withstand voltage at 200 ° C. were measured and evaluated by the methods shown below. .

[Method for measuring resistivity at room temperature and 200 ° C.]
The insulation resistance was measured for a multilayer ceramic capacitor sample at room temperature (20 ° C.) and 200 ° C. using a digital resistance meter (R8340 manufactured by ADVANTEST) under the conditions of a measurement voltage of 50 V (electric field strength of 5 V / μm) and a measurement time of 60 seconds. It was measured. The value of specific resistance was calculated from the electrode area and dielectric thickness of the multilayer ceramic capacitor sample. The specific resistance is preferably as high as possible, and it was judged to be good at 5.00 × 10 ¹⁰ Ωm or more at room temperature and 1.00 × 10 ⁹ Ωm or more at 200 ° C. In Table 2, the specific resistance is logarithmically displayed. When 5.00 × 10 ¹⁰ is logarithmically displayed, it is 10.7, and when 1.00 × 10 ⁹ Ωm is logarithmically displayed, it is 9.0.

[Calculation method of resistivity change rate]
The change rate of the specific resistance was calculated by using the following formula (1) for the change rate of the specific resistance Log (ρ _{(200 ° C.)} ) at _{200 ° C.} with respect to the specific resistance Log (ρ _(RT) ) at room temperature.
Rate of change (%) =
[Log (ρ _{(200 ° C.)} ) − Log (ρ _(RT) )] / Log (ρ _(RT) ) × 100 (1)
The change rate of the specific resistance is preferably as small as possible, and is determined to be -20% or less, more preferably -15% or less.

[DC withstand voltage measurement method]
A DC voltage was applied to the multilayer ceramic capacitor sample at 200 ° C. at a voltage increase rate of 100 V / sec, and the place where the leakage current exceeded 10 mA was defined as the DC withstand voltage. The DC withstand voltage is preferably 50 V / μm or more, and it is determined that 100 V / μm or more is good.

According to the results shown in Table 2, sample No. 1 to Sample No. 59, the multilayer ceramic capacitor sample within the scope of the present embodiment has the effect of suppressing the increase and movement of electrons, which are the majority carriers considered to be the main cause of the decrease in specific resistance. The Log (ρ _(RT) ) of the resistance is 10.7 or more, the Log (ρ _{(200 ° C.)} ) of the specific resistance at _{200 ° C.} is as high as 9.0 or more, and the change rate of the specific resistance is −20% or less. It was confirmed that it had a good insulating property of small.

In contrast, sample no. 5, Sample No. 10, Sample No. 15 is a majority carrier considered to be a main cause of a decrease in specific resistance because _x in the chemical formula (K _1-x Na _x ) Sr ₂ Nb ₅ O ₁₅ exceeds 0.40 and is outside the range of this embodiment. It is difficult to obtain an effect of suppressing the increase and movement of electrons, and the Log (ρ _(RT) ) having a specific resistance at room temperature is less than 10.7 and the Log (ρ _{(200 (C)} )) having a specific resistance of _{200 ° C.} is 9 It was as low as less than 0.0, and it was confirmed that the rate of change in specific resistance exceeded -20%.

Sample No. 11 to Sample No. 15, since the content of the first subcomponent is outside the range of the present embodiment, it is difficult to obtain an effect of suppressing the increase and movement of electrons, which are the majority carriers considered to be the main cause of the decrease in specific resistance, The specific resistance Log (ρ _(RT) ) at room temperature is less than 10.7, the specific resistance Log (ρ _{(200 ° C.)} ) at _{200 ° C.} is less than 9.0, and the rate of change in specific resistance is − It was confirmed that it exceeded 20%.

Sample No. 1 which is outside the scope of the present embodiment which does not include any one of MgO, BaO, B ₂ O ₃ , SiO ₂ and P ₂ O ₅ as the first subcomponent. 16 to Sample No. No. 20, Log (ρ _(RT) ) of specific resistance at room temperature is less than 10.7, and Log (ρ _{(200 ° C.)} ) of specific resistance at _{200 ° C.} is less than 9.0, and the change in specific resistance It was confirmed that the rate exceeded -20%.

When representing the first subcomponent in _{aMgO-bBaO-cB 2 O 3} -dSiO 2 -eP 2 O 5, wherein a, b, c, d, the relationship e is in the range of the present embodiment a + b + c + d + e = 1.00, 0.50 ≦ a ≦ 0.75, 0.02 ≦ b ≦ 0.15, 0.05 ≦ c ≦ 0.25, 0.05 ≦ d ≦ 0.25, 0.02 ≦ e ≦ Sample No. 1 satisfying 0.15 22 to Sample No. 24, Sample No. 27-Sample No. 30, Sample No. 33 to Sample No. 35, Sample No. 38 to Sample No. 40, sample no. 43 to Sample No. 46, Sample No. 48 to Sample No. 59 was able to further enhance the action of suppressing the increase and movement of electrons, which are majority carriers, so that the specific resistance Log (ρ _(RT) ) at room temperature was 11.5 or more and the specific resistance at 200 ° C. Log (ρ _{(200 ° C.)} ) was as high as 10.0 or more, and the rate of change in specific resistance was −15% or less, and it was confirmed that higher insulation could be realized.

Furthermore, 0.5 mol to 5.0 mol of at least one second subcomponent selected from La ₂ O ₃ , SnO ₂ , Y ₂ O ₃ , Sb ₂ O ₃ , Ta ₂ O ₅ , and Nb ₂ O ₅ is added. Sample No. contained 49-Sample No. 59, the specific resistance Log (ρ _(RT) ) at room temperature is 11.5 or higher, the specific resistance Log (ρ _{(200 ° C.)} ) at _{200 ° C.} is as high as 10.0 or more, and the specific resistance change It was confirmed that the DC withstand voltage at 200 ° C. was 100 V / μm or more in addition to the good insulating properties of a rate of −15% or less. Thus, by including a predetermined amount of the second subcomponent, it was possible to improve not only good insulating properties but also new physical properties such as high DC withstand voltage.

Example 2
Next, specific examples of the case where the dielectric composition contains a secondary phase containing MgO and P ₂ O ₅ will be described.

First, the sample No. 1 prepared in Example 1 was used. 49-Sample No. 59 green chips were prepared. The prepared green chip was subjected to binder removal treatment, firing, and annealing treatment described below to produce a multilayer ceramic sintered body containing a secondary phase.
It should be noted that the oxygen partial pressure of the firing conditions and the annealing treatment conditions are different from the conditions of Example 1.

(Binder removal)
Temperature increase rate: 100 ° C / hour Holding temperature: 400 ° C
Temperature holding time: 8.0 hours Atmospheric gas: Mixed gas of N ₂ and H ₂ humidified (firing)
Temperature rising rate: 1000 ° C./hour holding temperature: 1100 ° C. to 1300 ° C.
Temperature holding time: 1.0 hour Cooling rate: 200 ° C./hour Atmospheric gas: Mixed gas of humidified N ₂ and H ₂ Oxygen partial pressure: 10 ⁻³ to 10 ⁻⁵ Pa
(Annealing treatment)
Holding temperature: 800 ° C to 850 ° C
Temperature holding time: 5.0 hours temperature rise, temperature drop rate: 200 ° C./hour Atmosphere gas: humidified N ₂ gas

  As a result of performing composition analysis of each sample using ICP emission spectroscopic analysis for each obtained multilayer ceramic sintered body, it was confirmed that the value was almost equivalent to the dielectric composition described in Table 3. did.

なお、実施例１で作製した積層セラミックコンデンサ試料と区別するため、実施例２で作製したものは、新たに試料番号を付与している。（試料Ｎｏ．６０〜試料Ｎｏ．７０）

In addition, in order to distinguish from the multilayer ceramic capacitor sample produced in Example 1, those produced in Example 2 are newly assigned sample numbers. (Sample No. 60 to Sample No. 70)

  The obtained multilayer ceramic fired body was polished and attached with external electrodes in the same manner as in Example 1, and the sample Nos. Of the same shape were used. 60 to sample no. 70 multilayer ceramic capacitor samples were obtained.

  The obtained sample No. 60 to sample no. For 70 multilayer ceramic capacitor samples, the specific resistance at room temperature, 200 ° C. and 250 ° C., the rate of change in specific resistance at that time, the DC withstand voltage at 200 ° C., and the area ratio of the secondary phase by image analysis are as follows. Measurements and evaluations are shown in Table 4.

[Specific resistance measurement method at room temperature, 200 ° C. and 250 ° C.]
For a multilayer ceramic capacitor sample, at room temperature (20 ° C.), 200 ° C., 250 ° C., with a digital resistance meter (R8340 manufactured by ADVANTEST) under the conditions of a measurement voltage of 10 V (electric field strength of 5 V / μm) and a measurement time of 60 seconds. Insulation resistance was measured. The value of specific resistance was calculated from the electrode area and dielectric thickness of the multilayer ceramic capacitor sample. The specific resistance is preferably as high as possible, and it was judged to be 5.00 × 10 ¹⁰ Ωm or more at room temperature and 1.00 × 10 ⁹ Ωm or more at 200 ° C. and 250 ° C. In Table 4, the specific resistance is displayed in logarithm, and when 5.00 × 10 ¹⁰ is logarithmically displayed, it is 10.7, and when 1.00 × 10 ⁹ Ωm is logarithmically displayed, it is 9.0.

[Calculation method of resistivity change rate]
The change rate of the specific resistance is expressed by the following equation ₍₂ ) for the change rate of the specific resistance Log (ρ _{(200 ° C. or 250 ° C.)} ) at _{200 ° C. or 250 ° C.} with respect to the specific resistance Log (ρ _(RT) ) at room temperature. ).
Rate of change (%) =
[Log (ρ _{(200 ° C. or 250 ° C.)} ) − Log (ρ _(RT) )] / Log (ρ _(RT) ) × 100 (2)
The change rate of the specific resistance is preferably as small as possible, and is determined to be -20% or less, more preferably -15% or less.

[DC withstand voltage measurement method]
A DC voltage was applied to the multilayer ceramic capacitor sample at 200 ° C. at a voltage increase rate of 100 V / sec, and the place where the leakage current exceeded 10 mA was defined as the DC withstand voltage. The DC withstand voltage is preferably 50 V / μm or more, and it is determined that 100 V / μm or more is good.

[Area ratio of secondary phase by image analysis]
Microsampling was performed on the multilayer ceramic capacitor sample obtained by firing using FIB (Focused Ion Beam) to prepare a TEM sample of a dielectric layer. This TEM sample was subjected to STEM-EDS (Scanning Transmission Electron Microscopy-Energy Dispersive X-ray Spectrometry) mapping using JEM2200FS, a scanning transmission electron microscope manufactured by JEOL. The visual field of mapping was 7 μm × 7 μm, and 10 or more visual fields were mapped to each sample. Using the element maps obtained by these methods, Mg, P, which are main component elements of 3MgO · P ₂ O ₅ phosphate crystals, and (MgO · BaO) -P ₂ O ₅ phosphate crystals The areas of Mg, Ba, and P, which are the main component elements, were specified, and the area ratio was calculated using the average area of the results of 10 fields or more, and the area occupied by the entire secondary phase was calculated. In this embodiment, in order to reduce the rate of change in specific resistance in a wider temperature range from room temperature to 250 ° C., it is determined that the area occupied by the secondary phase is 2.0% to 15.0%. did.

なお、前記表４中の〇は、二次相が存在していることを意味している。

In Table 4, “◯” means that a secondary phase is present.

  According to Table 4, a sample having a secondary phase and an area ratio of 2.0% to 15% has a change rate of a specific resistance at 250 ° C. with respect to a specific resistance at room temperature of −20% or less. It was confirmed that good insulating properties can be maintained even in a wider temperature range.

  It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above embodiments and examples but by the scope of claims, and is intended to include all modifications and variations within the scope and meaning equivalent to the scope of claims.

  Since it has good insulation in a wide temperature range from room temperature to 200 ° C or 250 ° C, it is mounted in an environment close to the engine room for in-vehicle use, and also in the vicinity of power devices using SiC or GaN-based semiconductors. It can also be used as an electronic component.

DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor 2 Dielectric layer 3 Internal electrode layer 4 External electrode 10 Capacitor element body

Claims (5)

In the dielectric composition mainly comprising a tungsten bronze complex oxide represented by the chemical formula (K _1-x Na _x ) Sr ₂ Nb ₅ O ₁₅ (where 0 ≦ x ≦ 0.40), It contains MgO, BaO, B ₂ O ₃ , SiO ₂ and P ₂ O ₅ as subcomponents, and the total content of the subcomponents is 2.5 mol to 20.0 mol with respect to 100 mol of the main components, A dielectric composition. The first _{subcomponent, aMgO-bBaO-cB 2 O} 3 -dSiO 2 -eP 2 when expressed in _{O 5,} wherein a, b, c, d, the relationship e is a + b + c + d + e = 1.00
0.50 ≦ a ≦ 0.75
0.02 ≦ b ≦ 0.15
0.05 ≦ c ≦ 0.25
0.05 ≦ d ≦ 0.25
0.02 ≦ e ≦ 0.15
The dielectric composition according to claim 1, wherein: Furthermore, as the second subcomponent, at least one selected from La ₂ O ₃ , SnO ₂ , Y ₂ O ₃ , Sb ₂ O ₃ , Ta ₂ O ₅ and Nb ₂ O ₅ is added to 100 mol of the main component. The dielectric composition according to claim 1, wherein the dielectric composition contains 0.5 mol to 5.0 mol. When the dielectric composition contains a secondary phase containing MgO and P ₂ O ₅ and the total area of the cross section of the dielectric composition is 100%, the area occupied by the secondary phase in the cross section is The dielectric composition according to any one of claims 1 to 3, wherein the dielectric composition is 2.0% to 15.0%. An electronic component having a dielectric layer and an internal electrode layer, wherein the dielectric layer is made of the dielectric composition according to any one of claims 1 to 4.

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