JP2012201530A - Dielectric ceramic composition and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric ceramic composition showing excellent property under high electric field intensity and an electronic component where the dielectric ceramic composition is applied to a dielectric layer.SOLUTION: The dielectric ceramic composition has a plurality of dielectric particles and a grain boundary existing between dielectric particles. The dielectric particles contains particles having a core shell construction comprising shell which exists in the core and the periphery of the core and where Mn is present in a solid solution and the Mn amount existing in the grain boundary with respect to the Mn amount existing in the shell is 4 times and more. It is preferable that an average crystal grain size of the dielectric particles is 0.3 μm or less. It is preferable that the dielectric ceramic composition contains barium titanate as the main component and contains an oxide of a rare earth element, the oxide of Ba and/or Ca, an oxide of Mn, one or more oxide selected from Mg, V, Zr and Cr, an oxide containing Si, as the accessory component.

Description

  The present invention relates to a dielectric ceramic composition and an electronic component in which the dielectric ceramic composition is applied to a dielectric layer. More specifically, the present invention relates to a dielectric ceramic composition having good characteristics such as reliability, and an electronic component to which the dielectric ceramic composition is applied.

  In recent years, there is a high demand for miniaturization of electronic components accompanying higher density of electronic circuits. For example, monolithic ceramic capacitors, which are examples of electronic components, are rapidly becoming smaller and having larger capacities, and applications are expanding accordingly. As a result, such capacitors are required to have various characteristics.

  For example, the medium- and high-voltage capacitors used at a high rated voltage (for example, 100 V or more) are ECM (engine electric computer module), fuel injection device, electronic control throttle, inverter, converter, HID headlamp unit, hybrid engine battery. It is suitably used for devices such as control units and digital still cameras.

  When used at a high rated voltage as described above, it will be used under high electric field strength, but when the electric field strength increases, the insulation resistance tends to decrease. As a result, there is a problem that the reliability in the use environment is lowered. Further, such a problem becomes more prominent as the dielectric layer becomes thinner.

For example, in Patent Document 1, the composition formula is represented by 100 (Ba _1-x Ca _x ) _m TiO ₃ + aMnO + bCuO + cSiO ₂ + dMgO + eRO, and a, b, c, d, e, and m in the composition formula are in a specific range. A multilayer ceramic capacitor having a dielectric ceramic having an average particle size of 0.35 to 0.65 μm is disclosed. It is described that this multilayer ceramic capacitor can ensure reliability even if the dielectric ceramic layer is thinned to 1 μm or less.

  However, since Patent Document 1 describes characteristics when the electric field strength is relatively low, improvement in characteristics such as reliability under higher electric field strength has been demanded.

JP 2010-180124 A

  The present invention is made in view of such a situation, and provides a dielectric ceramic composition exhibiting good characteristics even under high electric field strength, and an electronic component in which the dielectric ceramic composition is applied to a dielectric layer. For the purpose.

In order to achieve the above object, the dielectric ceramic composition according to the present invention comprises:
A dielectric ceramic composition having a plurality of dielectric particles and a grain boundary existing between the dielectric particles,
The dielectric particles include particles having a core-shell structure including a core and a shell present around the core and in which Mn is dissolved,
The amount of Mn present at the grain boundary with respect to the amount of Mn present in the shell is four times or more.

  In the present invention, core-shell structured particles in which Mn is dissolved in the shell are present, and the amount of Mn in the shell and the amount of Mn in the grain boundary are within the above ranges. That is, the amount of Mn differs between the core, the shell, and the grain boundary, and Mn is selectively present at the grain boundary rather than the shell. In the dielectric ceramic composition having such a structure, a large amount of Mn is present at the grain boundary almost uniformly, and as a result, the insulation of the grain boundary is improved, the grain boundary resistance is improved, and the good life is achieved. Characteristics are obtained.

  Preferably, the dielectric particles have an average crystal particle size of 0.3 μm or less. By setting the average crystal grain size in the above range, the number of grain boundaries increases, and thus the effect of the present invention can be further enhanced.

  Preferably, the dielectric ceramic composition contains barium titanate as a main component, and an oxide of R element as a subcomponent (R element is Sc, Y, La, Ce, Pr, Nd, Pm, At least one selected from the group consisting of Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and an oxide of an A element (the A element is selected from the group consisting of Ba and Ca) At least one), an oxide of B element (B element is Mn and at least one selected from the group consisting of Mg, V, Zr and Cr), and an oxide containing Si. .

Preferably, the content of the oxide of the R element is 1.0 to 3.0 mol in terms of R ₂ O ₃ and the content of the oxide of the A element is 100 mol per 100 mol of the barium titanate. 0.5 to 2.0 mol in terms of BaO and CaO, and the content of the oxide of the B element is 3.0 to _{5 in} terms of MnO, MgO, V ₂ O ₅ , ZrO ₂ and Cr ₂ O _3. The content of the oxide including 0.0 mol and Si is 0.5 to 2.0 mol in terms of SiO ₂ .

  Preferably, the content of the Mn oxide is 1.0 to 2.0 mol in terms of MnO.

  By setting the composition of the dielectric ceramic composition as described above, the above-described structure can be easily obtained, and the above-described effects can be obtained.

  In addition, an electronic component according to the present invention has a dielectric layer composed of the dielectric ceramic composition described in any one of the above, and an electrode. Although it does not specifically limit as an electronic component, The electronic component for medium-high voltage used by a high rated voltage is preferable. Examples of such electronic components include multilayer ceramic capacitors, piezoelectric elements, chip inductors, chip varistors, chip thermistors, chip resistors, and other surface mount (SMD) chip type electronic components.

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of the dielectric layer 2 shown in FIG. FIGS. 3A and 3B are schematic diagrams for explaining a method of measuring the amount of Mn in the shell of dielectric particles and the amount of Mn at the grain boundary. FIG. 4 is a TEM photograph of a region in which the amount of Mn at the shell and the amount of Mn at the grain boundary were measured for the samples according to Examples and Comparative Examples of the present invention.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

(Multilayer ceramic capacitor 1)
As shown in FIG. 1, the multilayer ceramic capacitor 1 includes 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 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.

(Dielectric layer 2)
The dielectric layer 2 is composed of a dielectric ceramic composition according to this embodiment. The dielectric ceramic composition has a plurality of dielectric particles and a grain boundary existing between the dielectric particles.

(Dielectric particles and grain boundaries)
In the present embodiment, the dielectric particles include particles in which Mn is dissolved (diffused) in the main component particles. As shown in FIG. 2, the particles have a core-shell structure composed of a core 21a consisting essentially of the main component and a shell 21b existing around the core 21a and having Mn diffused in the main component. Crystal particles (core-shell structure particles 21). That is, the core 21a is substantially composed of a main component, and the shell 21b is composed of a main component in which Mn is dissolved. In addition, elements other than Mn may be dissolved in the main component particles.

  As shown in FIG. 2, the dielectric particles may include particles 20 that do not have a core-shell structure. In general, the presence or absence of the core-shell structure is determined based on the difference in contrast between the core and the shell or the density of the element dissolved in the main component based on the cross-sectional photograph of the dielectric layer 2. For this reason, there are core-shell structured particles in which only the shell appears in the cross-sectional photograph even though it actually has the core-shell structure.

  The grain boundary 22 is mainly composed of an oxide of an element contained in the dielectric layer, but may include an oxide of an element mixed as an impurity in the manufacturing process. Moreover, the oxide of the element which comprises an internal electrode layer may be contained. Usually, the grain boundary 22 is mainly composed of amorphous material, but may be composed of crystalline material.

  In the present embodiment, the grain boundary 22 contains Mn as an oxide or a composite oxide, and exists almost uniformly at the grain boundary. Therefore, the dielectric layer 2 has almost no segregation mainly composed of Mn.

  Mn is easily dissolved in dielectric particles. When Mn is contained in dielectric particles, the balance of charges in the particles is lost and oxygen defects are generated. Since the lifetime of the insulation resistance is reduced due to the movement of the oxygen defects, it is preferable that the number of oxygen defects is small. Therefore, normally, the content of Mn in the dielectric ceramic composition is reduced. On the other hand, when Mn is present at the grain boundary, Mn has a role of increasing the grain boundary resistance, and as a result, contributes to the improvement of the life of the insulation resistance.

  Therefore, in the present embodiment, the amount of Mn at the grain boundary is set larger than the amount of Mn in the shell of the dielectric particles (core-shell structure particles). Specifically, the amount of Mn at the grain boundary is 4 times or more, preferably 7 times or more, the amount of Mn in the shell.

  By making the relationship between the amount of Mn in the shell and the amount of Mn in the grain boundary within the above range, the effect of increasing the grain boundary resistance is more advantageous than the decrease in life due to the movement of oxygen defects. Lifetime can be greatly increased.

  The method for measuring the amount of Mn in the shell and the amount of Mn in the grain boundary is not particularly limited, and for example, it may be measured by analyzing a mapping image of Mn. In the present embodiment, the amount of Mn at the shell and the amount of Mn at the grain boundary are measured as follows.

  First, a dielectric layer and a grain boundary are discriminated by observing the dielectric layer using a transmission electron microscope (TEM). Furthermore, using an energy dispersive X-ray spectrometer (EDS) attached to the TEM, point analysis at the grain boundary is performed, and the content ratio of each element at the grain boundary is calculated.

  Specifically, a cross section of the dielectric layer is photographed with a TEM to obtain a bright field (BF) image. In this bright field image, a region that exists between dielectric particles and has a contrast different from that of the dielectric particles is defined as a grain boundary. The determination of whether or not the contrast is different may be made by visual observation, or may be made by software or the like that performs image processing.

  Subsequently, as shown in FIG. 3A, in the region determined to be the grain boundary 22, point analysis is performed by EDS, characteristic X-rays obtained by the analysis are analyzed, and the amount of Mn is calculated. At this time, measurement conditions such as a beam diameter, an acceleration voltage, and a CL aperture are adjusted so that information on elements contained in regions other than the grain boundaries, such as dielectric particles, is not detected. The number of measurement points is not particularly limited, but is preferably 5 points or more.

  The amount of Mn is calculated as the ratio of Mn atoms when the total content ratio of all elements detected at the measurement point is 100 atomic%. And the average value of the amount of Mn in each measurement point is calculated, and this value is made into the amount of Mn in a grain boundary.

  Next, as shown in FIG. 3A, the same measurement as described above is performed on the shell 21b of the core-shell structured particle 21, and the Mn amount in the shell 21b is calculated. As a method of discriminating between the core 21 a and the shell 21 b of the core-shell structured particle 21, it may be performed visually from a bright-field image of the particle, a mapping image showing the distribution of Mn and R elements in the particle, or image processing. It may be determined by software that performs the above.

  The measurement point on the shell 21b is preferably near the center of the shell 21b. In the present embodiment, a point at a distance of about 5 nm from the grain boundary 22 toward the center of the core-shell structured particle 21 is near the center of the shell. One or more measurement points correspond to one measurement point at the grain boundary 22. Therefore, the number of measurement points is preferably 5 points or more, and more preferably, measurement points are selected from 5 or more arbitrarily selected particles. And let the average value of the amount of Mn in each measurement point be the amount of Mn in the shell 21b.

  Then, as shown in FIG. 3B, the amount of Mn at the grain boundary and the amount of Mn at the shell (n) are compared, and the amount of Mn at the grain boundary is four times or more the amount of Mn at the shell ( 4n or more).

  The above-described structure is achieved, for example, by controlling the composition, particle diameter, firing conditions, etc. of the dielectric ceramic composition.

  In the present embodiment, the average crystal particle diameter of the dielectric particles is preferably 0.3 μm or less. By setting the average crystal particle diameter in the above range, the number of grain boundaries can be increased. As a result, even when the dielectric layer is thinned, there are many grain boundaries in the dielectric layer, so the grain boundary resistance contributes to the improvement of the insulation resistance. As a result, the reliability such as the life of the insulation resistance can be improved.

  Note that the average crystal particle diameter of the dielectric particles may be calculated as follows, for example. First, the capacitor element body 10 is cut along a plane parallel to the lamination direction of the dielectric layer 2 and the internal electrode layer 3. Then, the area of the dielectric particles in the cross section is measured, the diameter of the circle corresponding to the area (circle equivalent diameter) is calculated, and the value obtained by multiplying the circle equivalent diameter by 1.27 is taken as the crystal particle diameter.

  The method for calculating the average crystal particle size from the obtained crystal particle size is not particularly limited. For example, the crystal particle size is measured for 150 or more dielectric particles, and the cumulative frequency distribution of the obtained crystal particle size is used. A value at which the accumulation is 50% may be set as the average crystal particle diameter.

  In this embodiment, in order to easily obtain the above structure, the dielectric ceramic composition preferably includes the following components.

First, the dielectric ceramic composition preferably includes barium titanate having a perovskite structure as a main component. In barium titanate (BaTiO ₃ ), the Ba / Ti ratio indicating the ratio of Ba (A site atom) to Ti (B site atom) may be slightly deviated from the stoichiometric composition. In this embodiment, since the average crystal particle diameter of the dielectric particles can be finely controlled, the Ba / Ti ratio is preferably 1.000 or more. Also, the amount of oxygen (O) may be slightly deviated from the stoichiometric composition.

  The dielectric ceramic composition preferably includes an oxide of R element, an oxide of A element, an oxide of B element and an oxide containing Si as subcomponents.

The content of the oxide of R element is preferably 1.0 to 3.0 mol in terms of R ₂ O _{3 with} respect to 100 mol of barium titanate. By setting the content of the R element oxide within the above range, there is an advantage that the charge in the dielectric particles is compensated and the high temperature accelerated lifetime can be improved. The R element is at least one selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; It is preferably at least one selected from Tb, Dy and Ho.

  The oxide of element A is a component that easily replaces the A site mainly in the perovskite structure. In the present embodiment, the A element is Ba and / or Ca. The content is preferably 0.5 to 2.0 mol in terms of BaO and CaO with respect to 100 mol of barium titanate. By setting the content of the oxide of the element A within the above range, there is an advantage that the crystal particle diameter can be reduced. In addition, the oxide of the element A is preferably contained as an oxide, not as a glass.

The oxide of the B element is a component that easily replaces the B site in the perovskite structure. In the present embodiment, the B element is Mn and at least one selected from Mg, V, Zr and Cr. That is, B element makes Mn essential and further contains elements such as Mg. The content is preferably 3.0 to 5.0 mol in terms of MnO, MgO, V ₂ O ₅ , ZrO ₂ and Cr ₂ O _{3 with} respect to 100 mol of barium titanate. By setting the content of the B element oxide within the above range, there is an advantage that Mn is easily precipitated at the grain boundary and the grain boundary resistance can be improved.

  Moreover, preferable content in Mn independent is 1.0-2.0 mol in conversion of MnO. By setting the content of Mn within the above range, Mn exceeding the solid solubility limit in the dielectric particles is likely to precipitate at the grain boundaries.

The content of the oxide containing Si is preferably 0.5 to 2.0 mol in terms of SiO _{2 with} respect to 100 mol of barium titanate. The oxide containing Si works as a sintering aid. Further, the oxide containing Si is not particularly limited, but in the present embodiment, SiO ₂ is preferable.

  The dielectric ceramic composition according to the present embodiment may further contain other components according to desired characteristics.

  The thickness of the dielectric layer 2 is preferably about 1 to 2 μm per layer in order to meet the demand for thinning.

  The number of laminated dielectric layers 2 is not particularly limited, but is preferably 20 or more. The upper limit of the number of stacked layers is not particularly limited, but is about 2000, for example.

(Internal electrode layer 3)
The conductive material contained in the internal electrode layer 3 is not particularly limited, and a known conductive material such as Ni or Ni alloy may be used. The thickness of the internal electrode layer 3 may be appropriately determined according to the application and the like, but is usually preferably about 0.1 to 3 μm.

(External electrode 4)
The conductive material contained in the external electrode 4 is not particularly limited, and for example, a known conductive material such as Ni, Cu, or an alloy thereof may be used. The thickness of the external electrode 4 may be appropriately determined according to the application and the like, but is usually preferably about 10 to 50 μm.

(Manufacturing method of multilayer ceramic capacitor 1)
What is necessary is just to manufacture the multilayer ceramic capacitor 1 of this embodiment by a well-known method. In the present embodiment, a multilayer chip is manufactured by producing a green chip using a paste and firing it. Hereinafter, the manufacturing method will be specifically described.

  First, a dielectric material for forming a dielectric layer is prepared, and this is made into a paint to prepare a dielectric layer paste.

  In the present embodiment, as the dielectric material, first, a barium titanate material and a subcomponent material are prepared. The raw material of the subcomponent includes at least a raw material of an oxide of Mn. In the present embodiment, the subcomponent materials include an R element oxide material, an A element oxide material, a B element oxide material excluding Mn, and an Si-containing oxide material. , Are preferably further included.

  As these raw materials, an oxide, a mixture thereof, or a composite oxide can be used. Moreover, you may use the various compounds used as an oxide mentioned above or complex oxide by baking.

  The dielectric layer paste is obtained by kneading the dielectric raw material, a binder, and a solvent. Known binders and solvents may be used. The paste may contain an additive such as a plasticizer as necessary.

  The internal electrode layer paste is obtained by kneading the conductive material, a binder, and a solvent. Known binders and solvents may be used. The paste may contain additives such as a co-material and a plasticizer as necessary.

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

  Using the obtained paste, green sheets and internal electrode patterns are formed and laminated to obtain a green chip.

  The obtained green chip is subjected to a binder removal process. The binder removal treatment condition may be a known condition. For example, the holding temperature is preferably 180 to 400 ° C.

  After the binder removal treatment, the green chip is fired to obtain a capacitor element body as a sintered body. The firing conditions may be known conditions. For example, the holding temperature is preferably 1300 ° C. or lower in a reducing atmosphere.

  After firing, the obtained capacitor element body is preferably subjected to reoxidation treatment (annealing). The annealing conditions may be known conditions. For example, it is preferable that the oxygen partial pressure during annealing is higher than the oxygen partial pressure during firing, and the holding temperature is 1100 ° C. or lower.

  The capacitor element main body obtained as described above is subjected to end surface polishing, and an external electrode paste is applied and baked 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.

  The multilayer ceramic capacitor of this embodiment manufactured in this way is mounted on a printed circuit board or the like by soldering or the like and used for various electronic devices.

  As mentioned above, although embodiment of this invention was 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.

  For example, in the embodiment described above, a multilayer ceramic capacitor is exemplified as the ceramic electronic component according to the present invention. However, the ceramic electronic component is not limited to the multilayer ceramic capacitor, and may be an electronic component having the above-described configuration. Anything is fine. The electronic component according to the present invention is particularly suitable as an electronic component for medium to high pressure applications.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

First, BaTiO ₃ powder was prepared as a main component material. The raw materials shown below were prepared as subcomponent raw materials. Y ₂ O ₃ powder is prepared as the raw material for the oxide of R element, BaO powder and CaO powder are prepared as the raw material for the oxide of A element, and MnO powder, MgO powder and V ₂ O ₅ powder was prepared, and SiO ₂ powder was prepared as an oxide raw material containing Si, and these were pulverized. The Ba / Ti ratio of the BaTiO ₃ powder was the value shown in Table 1.

Next, the BaTiO ₃ powder prepared above and the pulverized subcomponent raw material were wet pulverized with a ball mill for 5 hours and dried to obtain a dielectric raw material. In addition, the addition amount of each subcomponent was set to the amount shown in Table 1 in terms of each element with respect to 100 mol of BaTiO _{3 as} the main component in the dielectric ceramic composition after firing.

  Next, 100 parts by weight of the obtained dielectric material, 10 parts by weight of polyvinyl butyral resin, 5 parts by weight of dioctyl phthalate (DOP) as a plasticizer, and 100 parts by weight of alcohol as a solvent are mixed with a ball mill to obtain a paste. To obtain a dielectric layer paste.

  Further, 44.6 parts by weight of Ni particles, 52 parts by weight of terpineol, 3 parts by weight of ethyl cellulose, and 0.4 parts by weight of benzotriazole are kneaded with three rolls to form a paste for an internal electrode layer. did.

  Then, using the dielectric layer paste prepared above, a green sheet was formed on the PET film so that the thickness after drying was 2 μm. Next, the electrode layer was printed in a predetermined pattern using the internal electrode layer paste thereon, and then the sheet was peeled off from the PET film to produce a green sheet having the electrode layer. Next, a plurality of green sheets having electrode layers were laminated and pressure-bonded to obtain 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 under the following conditions to obtain a sintered body as a capacitor element body.

  The binder removal processing conditions were a temperature rising rate of 25 ° C./hour, a holding temperature of 260 ° C., a temperature holding time of 8 hours, and an atmosphere in the air.

The firing conditions were a temperature rising rate and a temperature falling rate of 600 ° C./hour, a holding temperature of 1200 to 1300 ° C., and a holding time of 2 hours. The atmospheric gas was a humidified N ₂ + H ₂ mixed gas (oxygen partial pressure: 10 ⁻¹³ MPa).

The annealing conditions were a temperature rising rate and a temperature falling rate of 200 ° C./hour, a holding temperature of 1050 ° C., and a temperature holding time of 2 hours. The atmosphere gas was humidified N ₂ gas (oxygen partial pressure: 10 ⁻⁷ MPa).

  Next, the end surface of the obtained sintered body was polished by sand blasting, and then an In—Ga alloy was applied as an external electrode to obtain a multilayer ceramic capacitor sample shown in FIG. The size of the obtained capacitor sample is 2.0 mm × 1.2 mm × 0.6 mm, the thickness of the dielectric layer is about 1.6 μm, the thickness of the internal electrode layer is 1.4 μm, and is sandwiched between the internal electrode layers The number of dielectric layers was 5.

  About the obtained capacitor | condenser sample, the average crystal grain diameter was measured and the amount of Mn in a shell and the amount of Mn in a grain boundary were computed. Furthermore, the specific dielectric constant, dielectric loss, insulation resistance (IR) and high temperature accelerated lifetime (HALT) were measured by the methods shown below.

(Average crystal particle size)
The capacitor sample was cut, the cut surface was observed with a scanning electron microscope (SEM), and a SEM photograph was taken. The SEM photograph was subjected to image processing by software, the boundaries of the dielectric particles were determined, and the area of each dielectric particle was calculated. Then, the crystal particle diameter was calculated by converting the calculated area of the dielectric particles into the equivalent circle diameter. This measurement was performed on 150 dielectric particles, and the average value was defined as the average crystal particle size. The average crystal particle size was 0.30 μm or less. The results are shown in Table 3.

(Mn content at grain boundaries and Mn content at shell)
First, the capacitor sample was cut along a plane perpendicular to the dielectric layer. The cut surface was observed with a transmission electron microscope (TEM) to discriminate between core-shell structured particles and grain boundaries, and further discriminate between cores and shells in the core-shell structured particles. Subsequently, point analysis was performed using an EDS apparatus attached to the TEM at arbitrarily selected five grain boundaries. The characteristic X-ray obtained by the measurement was quantitatively analyzed, and the proportion of Mn in the content ratio of the detected element was calculated. By calculating the average value of the ratio of Mn obtained at each measurement point, the amount of Mn at the grain boundary was calculated.

  Further, the Mn amount in the shell was calculated in the same manner as described above at five points arbitrarily selected near the center of the shell of the dielectric particles existing in the vicinity of the measurement point of the Mn amount at the grain boundary. For Sample Nos. 2 and 4, a TEM photograph of the region where the Mn amount at the grain boundary and the Mn amount at the shell were measured is shown in FIG. 4, and the Mn amount at the grain boundary and the Mn amount at the shell are shown in Table 2. Further, in Table 3, for each sample, when the amount of Mn at the grain boundary relative to the amount of Mn in the shell is 7 times or more, “◎”, when it is 4 times or more, “◯”, less than 4 times. The case was described as “×”.

(Relative permittivity ε)
The relative dielectric constant ε was measured on a capacitor sample at a reference temperature of 25 ° C. using a digital LCR meter (4284A manufactured by HP) under conditions of a frequency of 1 kHz and an input signal level (measurement voltage) of 1.0 Vrms. Calculated from the electric capacity. A higher relative dielectric constant is preferable, and in this example, a sample having a relative dielectric constant of 1500 or more was judged to be good. The results are shown in Table 3.

(Dielectric loss (tan δ))
The dielectric loss (tan δ) was measured for a capacitor sample at a reference temperature of 25 ° C. with a digital LCR meter (4284A manufactured by HP) under conditions of a frequency of 1 kHz and an input signal level (measurement voltage) of 1.0 Vrms. It is preferable that the dielectric loss is low. In this example, a sample having a dielectric loss of 4% or less was judged to be good. The results are shown in Table 3.

(High temperature accelerated life (HALT))
The capacitor sample was held at 190 ° C. under an electric field of 10 V / μm in a DC voltage applied state, and the lifetime was measured to evaluate the high temperature accelerated lifetime. In this example, the time from the start of application until the insulation resistance drops by an order of magnitude was defined as the failure time, and the average failure time (MTTF) calculated by performing Weibull analysis was defined as the lifetime. In this example, the above evaluation was performed on 20 capacitor samples, and the average value was defined as the high temperature accelerated life. In this example, a sample having a high temperature accelerated lifetime of 100 hours or more was judged to be good. The results are shown in Table 3.

  4 and Table 2, in sample number 4, it was confirmed that the amount of Mn at the grain boundary was four times or more larger than the amount of Mn in the shell. On the other hand, in sample number 2, it was confirmed that the amount of Mn at the grain boundary and the amount of Mn at the shell hardly changed.

  From Table 3, when the amount of Mn at the grain boundary relative to the amount of Mn in the shell is less than 4 times (sample numbers 1 to 3, 7 to 15, 17 and 18), it can be confirmed that the high temperature accelerated life is inferior. It was. That is, the reliability is poor under a high electric field strength.

  On the other hand, when the amount of Mn at the grain boundary with respect to the amount of Mn in the shell is 4 times or more (sample numbers 4 to 6, 16 and 19), it was confirmed that the high temperature accelerated life was good. In particular, it has been confirmed that the high temperature accelerated life is very good when the Mn content at the grain boundary with respect to the Mn content in the shell is 7 times or more. It was also confirmed that the average crystal particle size is preferably 0.3 μm or less.

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 10 ... Capacitor element body 2 ... Dielectric layer 21 ... Core-shell structure particle 21a ... Core 21b ... Shell 22 ... Grain boundary 3 ... Internal electrode layer 4 ... External electrode

Claims (6)

A dielectric ceramic composition having a plurality of dielectric particles and a grain boundary existing between the dielectric particles,
The dielectric particles include particles having a core-shell structure including a core and a shell present around the core and in which Mn is dissolved,
The dielectric ceramic composition characterized in that the amount of Mn present at the grain boundary with respect to the amount of Mn present in the shell is four times or more.   The dielectric ceramic composition according to claim 1, wherein an average crystal particle diameter of the dielectric particles is 0.3 μm or less. The dielectric ceramic composition contains barium titanate as a main component, and an oxide of R element as a subcomponent (R element is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu , Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), and
An oxide of element A (the element A is at least one selected from the group consisting of Ba and Ca);
An oxide of element B (element B is Mn and at least one selected from the group consisting of Mg, V, Zr and Cr);
The dielectric ceramic composition according to claim 1 or 2, comprising an oxide containing Si. The content of the oxide of the R element is 1.0 to 3.0 mol in terms of R ₂ O ₃ and the content of the oxide of the A element is BaO and CaO with respect to 100 mol of the barium titanate. 0.5 to 2.0 mol in terms of conversion, and the content of the B element oxide is 3.0 to 5.0 mol in terms of MnO, MgO, V ₂ O ₅ , ZrO ₂ and Cr ₂ O _3. The dielectric ceramic composition according to claim 3, wherein the content of the oxide containing Si is 0.5 to 2.0 mol in terms of SiO ₂ .   The dielectric ceramic composition according to claim 4, wherein a content of the Mn oxide is 1.0 to 2.0 mol in terms of MnO.   The electronic component which has a dielectric material layer comprised from the dielectric material ceramic composition in any one of Claims 1-5, and an electrode.

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