JP2006290675A - Dielectric ceramic composition and multilayer ceramic capacitor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric ceramic composition excellent in temperature characteristics while retaining a high dielectric constant, also particularly excellent in reliability such as breakdown voltage and insulation resistance, and a multilayer ceramic capacitor using the composition. <P>SOLUTION: This dielectric ceramic composition comprises as subcomponents at least magnesium in terms of MgO of 0.5-2.0 mol and a rare earth metal A (at least one kind selected from Dy, Ho and Y) and a rare earth metal B (at least one kind selected from Yb, Er and Tm) of total in terms of oxides of 2.0-5.0 mol to 100 mol barium titanate as a main component. Further the BET value of the dielectric ceramic composition is 100-150 when the BET value of the raw material powder of the barium titanate as the main component is set as 100. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a dielectric ceramic composition used for ceramic electronic parts widely used in electronic equipment and a multilayer ceramic capacitor using the same.

  Conventionally, this type of dielectric ceramic composition and multilayer ceramic capacitor using the same are widely used for dielectric layers such as ceramic composite parts including ceramic capacitors and capacitor elements. In particular, multilayer ceramic capacitors that can realize a small size and a large capacity have become mainstream. Furthermore, a large-capacity multilayer ceramic capacitor using a base metal as an internal electrode by using an inexpensive base metal (for example, nickel or copper) as a material for the internal electrode and firing in a neutral atmosphere or a reducing atmosphere from a cost standpoint. It has been put into practical use. It is necessary to develop a dielectric ceramic composition that is excellent in reduction resistance and has a sufficient dielectric constant after firing as a dielectric ceramic composition used in a multilayer ceramic capacitor having a base metal as an internal electrode.

  In the automobile industry, the multilayer ceramic capacitor is used in various electronic devices. Multilayer ceramic capacitors used in these electronic devices for electrical equipment are required to have excellent temperature characteristics while maintaining a high dielectric constant, and in particular, highly reliable capacitors such as dielectric breakdown voltage and insulation resistance.

In order to satisfy this required characteristic, the dielectric characteristics of the dielectric ceramic composition are almost dominant, and the conventional dielectric ceramic composition mainly composed of barium titanate has a Curie point near 125 ° C., Since the dielectric constant drops significantly at higher temperatures, the EIA standard X7R characteristic or X8R characteristic (capacity change rate is within ± 15% at -55 ° C to 150 ° C). ) Was difficult to satisfy. As a countermeasure, a method of pre-calcining the main component of barium titanate and various additives has been proposed (see, for example, Patent Document 1), or the Curie point of the main component of barium titanate is set to a higher temperature side. A method of adding an additive for shifting to (for example, see Patent Document 2) has been performed.
Japanese Patent No. 3340722 Japanese Patent No. 3340723

  However, each of the conventional configurations has a problem that the dielectric constant is high but the temperature characteristic does not satisfy the X8R characteristic, or the reliability or the dielectric constant is low even if the temperature characteristic is good. It has not yet been possible to level out the characteristics of the above.

  The present invention solves the above-described conventional problems, and has an excellent temperature characteristic while maintaining a high dielectric constant, and in particular, a dielectric ceramic composition excellent in reliability such as dielectric breakdown voltage and insulation resistance, and the like The object is to realize the multilayer ceramic capacitor used.

  In order to solve the above-mentioned conventional problems, the present invention provides at least magnesium as an auxiliary component in an amount of 0.5 to 2.0 mol in terms of MgO, rare earth metal A (Dy) with respect to 100 mol of barium titanate as a main component. , Ho, Y) and a rare earth metal B (at least one selected from Yb, Er, Tm) is a dielectric ceramic having a sum of 2.0 to 5.0 mol in terms of oxide A BET value of the dielectric ceramic composition is 100 to 150 when the BET value of the raw material powder of barium titanate is 100. is there.

  The dielectric ceramic composition of the present invention and the multilayer ceramic capacitor using the dielectric ceramic composition have excellent temperature characteristics while maintaining a high dielectric constant, and are excellent in dielectric ceramic composition having excellent reliability such as dielectric breakdown voltage and insulation resistance. And a multilayer ceramic capacitor using the same can be realized.

(Embodiment 1)
Hereinafter, a dielectric ceramic composition according to Embodiment 1 of the present invention and a multilayer ceramic capacitor using the same will be described with reference to the drawings.

  FIG. 1 is a partially cutaway perspective view of a multilayer ceramic capacitor according to Embodiment 1 of the present invention, and FIG. 2 is a crystal after firing of a dielectric ceramic composition used for a dielectric layer of the multilayer ceramic capacitor shown in FIG. FIG. 3 is a conceptual diagram of the structure, and FIG. 3 is a characteristic diagram showing temperature characteristics of the capacitance of the multilayer ceramic capacitor.

  As shown in FIG. 1, the multilayer ceramic capacitor according to Embodiment 1 of the present invention has a capacitor element body 3 having a structure in which dielectric layers 1 and internal electrode layers 2 are alternately stacked. Are arranged and laminated so that each end face is alternately exposed at two opposite ends of the capacitor element body 3. A pair of external electrodes 4 respectively connected to the internal electrode layers 2 alternately arranged inside the capacitor element body 3 are formed at both ends of the capacitor element body 3. The shape of the capacitor element body 3 is not particularly limited, but is usually a rectangular parallelepiped from the viewpoint of mountability.

  Further, there is no particular limitation on the size, and it may be an appropriate size according to the use, but L (0.6 to 5.6 mm) × W (0.3 to 5.0 mm) × t (0. 3 to 1.9 mm) is widely used.

  Note that various conditions such as the number and thickness of the dielectric layers 1 shown in FIG. 1 may be appropriately determined according to the purpose and application.

The dielectric layer 1 of this multilayer ceramic capacitor is formed using the dielectric ceramic composition of the present invention, and this dielectric ceramic composition is mainly composed of barium titanate represented by BaTiO ₃ . In the first embodiment, the characteristics of the dielectric ceramic composition were evaluated by producing a multilayer ceramic capacitor. Needless to say, the dielectric ceramic composition of the present invention can be used for all ceramic capacitors.

  In addition, the dielectric layer 1 of the multilayer ceramic capacitor of the present invention is composed of crystals (grains) and grain boundary phases, and the average particle size of the crystals (grains) of the dielectric layer 1 is about 0.1 to 2 μm. It is preferable.

  Next, the electrode material contained in the internal electrode layer 2 is not particularly limited, but recently it is desirable to use a base metal from the viewpoint of cost reduction. The base metal used as the electrode material is preferably Ni or a Ni alloy in consideration of the sintering temperature of the dielectric layer 1. This Ni alloy is preferably an alloy of Ni and one or more elements selected from Mn, Cr, Co and A1, and the Ni content in the alloy is preferably 95% by weight or more.

  Further, the thickness of the internal electrode layer 2 may be appropriately determined according to the use and the like, and is usually 0.5 to 5 μm, and about 0.7 to 2.0 μm for realizing a smaller size and a larger capacity. Is being put to practical use.

  Next, the electrode material used for the external electrode 4 is not particularly limited, but it is preferable to use Cu, Cu alloy, Ni, Ni alloy, or the like. Ag, Ag—Pd alloy, or the like can also be used. In the first embodiment, inexpensive Ni, Cu, or an alloy thereof is used. Furthermore, the thickness of the external electrode 4 may be appropriately determined according to the use, but is preferably about 0.6 to 50 μm.

In addition, the dielectric ceramic composition according to Embodiment 1 of the present invention is mainly composed of barium titanate represented by the chemical formula BaTiO ₃ , and the composition ratio of BaTiO ₃ in this BaTiO ₃ is in an arbitrary range. For example, it is preferable that 0.990 ≦ Ba / Ti ≦ 1.050. Further, considering the reduction resistance and low-temperature sintering properties of the capacitor element body 3 used in the multilayer ceramic capacitor, the composition ratio of Ba and Ti is more preferably 0.990 ≦ Ba / Ti ≦ 1.005. At this time, if the Ba / Ti ratio exceeds 1.005, the reactivity of the dielectric ceramic composition becomes sensitive to sintering, so it is desirable to select the combination with other additives.

  Further, with respect to 100 moles of barium titanate as the main component of the dielectric ceramic composition, 0.5 to 2.0 moles of Mg in terms of MgO and at least one selected from rare earth metals A (Dy, Ho, Y) Species) and rare earth metal B (at least one selected from Yb, Er, Tm) in terms of oxide, 2.0 to 5.0 moles, and the BET value in the raw material powder of barium titanate as the main component It is preferable that the dielectric layer 1 is formed using a dielectric ceramic composition in which the BET value of the dielectric ceramic composition is 100 to 150. The BET specific surface area was measured using a BET multipoint method. The measurement method is to prepare 1 g of powder to be measured, perform heat treatment to remove the adsorbed material by holding at 200 ° C. for 3 hours before measurement, and then use a measuring device (MICRO MERITICS JEMINI 2360 manufactured by Shimadzu Corporation). The BET specific surface area was measured. Nitrogen gas was used as the adsorption gas at the time of measurement, and the holding temperature at the time of measurement was −198 ° C. while cooling with liquid nitrogen. In general, when measuring the specific surface area by the BET multipoint method, it is desirable to measure a plurality of equilibrium pressures in the range of relative pressure (adsorption equilibrium pressure / saturated vapor pressure) of 0.05 to 0.3. In this measurement, the relative pressure was measured at five points of 0.050, 0.0875, 0.1250, 0.1625, 0.200. The BET values shown below were all measured by the above method.

  In addition, barium titanate used as a main component can be made into a raw material powder having a uniform particle size that can easily produce a core-shell structure by using, for example, an oxalate method (core-shell structure). Will be described later in detail). It is preferable that the BET value in such a raw material powder of barium titanate is 100 and the BET value of the dielectric ceramic composition adjusted to a predetermined dielectric composition is 100 to 150. It was found that when the BET value of the dielectric ceramic composition is lower than 100, the sinterability is lowered, and when it exceeds 150, the flatness of the temperature characteristics is deteriorated.

  Further, by setting Mg in the above range, the temperature characteristics of the dielectric constant can be flattened even if the dielectric constant of the dielectric ceramic composition is increased, and the solid solution amount of magnesium is excessively small. And the dielectric loss (tan δ) tends to deteriorate, so the lower limit of the solid solution amount is 0.5 mol. On the contrary, if the magnesium amount is excessive, the sinterability of the dielectric ceramic composition is extremely deteriorated. Preferably not exceeding 2.0 moles.

Further, by controlling the ratio of rare earth metal A and rare earth metal B within the range of the present invention, a predetermined temperature characteristic can be satisfied while maintaining a high dielectric constant. This is because the rare earth metal A and rare earth metal B mainly suppress the abnormal grain growth that occurs during firing, and at the time of forming the core-shell structure, the Mg is appropriately diffused inside the BaTiO ₃ to control the insulation resistance. (IR) and dielectric breakdown voltage (BDV) variations are considered to be reduced, the resistance to reduction is improved, and the dielectric constant is increased.

  Next, as shown in FIG. 2, the fine structure of the crystal particles produced using the dielectric ceramic composition constituting the dielectric layer 1 of the present invention is as follows: the core layer 5 made of barium titanate constituting the crystal particles; A core-shell structure composed of a shell layer 6 and a grain boundary layer 7 existing so as to surround the periphery is formed, and Mg, rare earth metal A, and rare earth metal B are segregated in the shell layer 6 portion. In particular, the rare earth metal A has a large ionic radius and is difficult to diffuse into the core layer 5 and contributes to sinterability and promotes grain growth. , Has the disadvantage of deteriorating the temperature characteristics. The rare earth metal B has a small ionic radius and is easily diffused into the lattice of Ba and Ti constituting the core layer 5, so that it exhibits the effect of controlling the temperature characteristics but has the disadvantage of inhibiting the sinterability. is doing.

In studying these, in order to obtain a dielectric ceramic composition excellent in temperature characteristics while maintaining a high dielectric constant and a multilayer ceramic capacitor using the same, the total amount of Mg, rare earth metal A and rare earth metal B By controlling the relationship between the combination ratio and total amount of BET and the BET value of the raw material powder of barium titanate and the BET value of the dielectric ceramic composition, the abnormal grain growth that occurs when BaTiO ₃ fine particles are fired is suppressed. And the amount of magnesium or magnesium oxide segregated in the grain boundary layer 7 existing between the adjacent core layers 6 in the dielectric ceramic composition is reduced, and as a result, the dielectric constant of the multilayer ceramic capacitor is reduced. It has been found that it is feasible to flatten the temperature characteristics while maintaining high.

  On the other hand, the grain boundary layer 7 is usually composed of an oxide of a substance constituting a dielectric material or an internal electrode material, an oxide of a material added separately, or an oxide of an element mixed as an impurity during the process. Depending on circumstances, it may be made of glass or glassy material.

  In addition to Mg and rare earth metal, at least one subcomponent selected from oxides such as V, Mo, Zn, Cd, Sn, Mn, and Al is added to the dielectric ceramic composition according to the present invention. It may be. By adding such a subcomponent, low temperature firing is possible without deteriorating the dielectric characteristics of the main component, and reliability failure when the dielectric layer 1 is thinned can be reduced, resulting in a long life. Can be achieved.

  Moreover, what is necessary is just to determine the content of each compound in the raw material of a dielectric ceramic composition so that it may become a composition of the above-mentioned dielectric ceramic composition after baking. As the compound that becomes an oxide by this firing, for example, carbonate, nitrate, oxalate, organometallic compound and the like can be used.

  The dielectric ceramic composition described above can exhibit the same effect in a ceramic capacitor which is a ceramic electronic component, a dielectric material which can be incorporated in a ceramic multilayer substrate, and the like.

  In addition, a method for manufacturing a multilayer ceramic capacitor using this dielectric ceramic composition includes a step of heat-treating barium titanate as a main component, a magnesium raw material, a rare earth metal A, and a rare earth metal B on the heat-treated barium titanate. Adding a predetermined amount to the solvent, adding a predetermined amount of resin and plasticizer to the mixed dielectric raw material to form a dielectric slurry, and adding the dielectric slurry to the dielectric After forming into a green sheet, printing the internal electrode pattern on the dielectric green sheet, laminating a predetermined number of printed dielectric green sheets, cutting into individual pieces, and singulation The laminated chip thus manufactured can be manufactured through a step of firing under predetermined firing conditions.

  In this method of manufacturing a multilayer ceramic capacitor, the average particle size of the dielectric ceramic composition before forming the dielectric slurry is preferably about 0.01 to 2 μm.

  The dielectric slurry may be an organic paint obtained by kneading a raw material for the dielectric ceramic composition and an organic vehicle, or may be a water-based paint.

  In addition, the electrode paste used for printing the internal electrode pattern includes the above-described electrode materials made of various conductive metals and alloys, or various oxides, organometallic compounds, resinates, and the like that become the above-mentioned electrode materials after firing, and the above-described organic vehicle. Can be prepared by kneading.

  Also, the external electrode paste formed after being separated into pieces can be adjusted in the same manner as the electrode paste used to form the internal electrode pattern.

In addition, the firing atmosphere of the laminated chip may be appropriately determined according to the type of electrode material in the internal electrode paste, but when a base metal such as Ni or Ni alloy is used as the conductive material, the oxygen partial pressure of the firing atmosphere Is preferably 10 ⁻¹⁰ to 10 ⁻³ Pa.

  Further, when the singulated laminated chip is baked under predetermined baking conditions, the holding temperature of baking is preferably 1000 to 1400 ° C. If this holding temperature is too low, densification becomes insufficient and the holding temperature is too high. The temperature characteristics of the capacitance deteriorate due to the discontinuity of the electrodes due to abnormal sintering of the internal electrode layer 2 or the diffusion of elements constituting the internal electrode layer 2. As other firing conditions, the heating rate is 50 to 500 ° C./hour, the holding time at the firing temperature is 0.5 to 8 hours, the cooling rate is 50 to 500 ° C./hour, the firing atmosphere is a reducing atmosphere, As the atmospheric gas, it is desirable to use a humidified mixed gas of nitrogen gas and hydrogen gas.

Furthermore, when firing in a reducing atmosphere, it is desirable to anneal (heat treat) the sintered body of the capacitor element body 3. This annealing is a process for re-oxidizing the dielectric layer 1, whereby the insulation resistance can be further increased. The oxygen partial pressure in the annealing atmosphere is preferably 10 ⁻⁴ Pa or more. If the oxygen partial pressure is too low, reoxidation of the dielectric layer 1 becomes difficult, and if the oxygen partial pressure is too high, the internal electrode layer 2 may be oxidized. The annealing holding temperature is preferably 1150 ° C. or lower. If the holding temperature of this annealing is too low, the reoxidation of the dielectric layer 1 is insufficient and the insulation resistance deteriorates. If the holding temperature is too high, the internal electrode layer 2 is oxidized and the capacitance is reduced. Without reacting with the dielectric material, the temperature characteristics of the capacitance and the insulation resistance deteriorate.

  In addition, the firing conditions may greatly affect the dielectric characteristics of the dielectric ceramic composition and the multilayer ceramic capacitor using the dielectric ceramic composition, and optimization is important.

  Next, it demonstrates still in detail using an Example.

Example 1
In Example 1, 100 samples of the internal electrode layer 2 of a 3216 type multilayer ceramic capacitor were produced as samples for evaluation.

First, with respect to 100 mol of barium titanate prepared by the oxalate method as a starting material for the dielectric ceramic composition, 1 mol of MgO, ₂ mol of Dy ₂ O _3, and 2 mol of Yb ₂ O ₃ are added as subcomponents. The raw material powder was weighed (see Table 1).

At this time, the BET specific surface area of the raw powder of barium titanate is desirably 3.0 to 7.0 m ² / g.

  In addition, a glass component or a transition metal oxide may be added.

  Moreover, the raw material powder produced with the other manufacturing method can also be used for the raw material of barium titanate.

  Next, a dielectric slurry was prepared by mixing these raw material powders with pure water. The amount of pure water at this time is preferably 25 to 50% of the solid content of the dielectric slurry.

  Further, this dielectric slurry was mixed for 24 hours by a ball mill using 10 mmφ zirconia balls (YZT) as a medium, and then dried in a drying furnace at 150 ° C.

  Next, the dried dielectric slurry was placed in a high-purity alumina crucible and calcined at 830 ° C. in air. The calcination temperature is preferably 750 to 950 ° C.

  Thereafter, the obtained calcined powder was again mixed with pure water to produce a dielectric slurry. The amount of pure water at this time is preferably added so that the solid content of the dielectric slurry is 25 to 50%. The dielectric slurry was mixed and ground for 48 hours by a ball mill using 10 mmφ zirconia balls (YZT) as a medium, and then dried in a drying furnace at 150 ° C.

  Next, a resin binder, a plasticizer, and an organic solvent are added to the pulverized powder of the calcined powder and mixed to obtain a dielectric slurry. The BET value of the dielectric ceramic composition after pulverization with respect to this dielectric slurry However, the dispersion was carried out while adjusting the pulverization conditions with a medium stirring mill so that the BET value of the main component barium titanate was 120 with respect to the BET value normalized to 100.

  Thereafter, a dielectric green sheet was produced by a doctor blade method using a dielectric slurry containing a dielectric ceramic composition produced so as to satisfy the above conditions. The dielectric green sheet was prepared by adjusting the thickness of the dielectric layer 1 to 10 μm after firing.

  Next, screen printing was performed on the dielectric green sheet using an internal electrode paste made of Ni powder having an average particle size of about 0.4 μm so as to obtain a desired internal electrode pattern of the internal electrode layer 2.

  A laminated body was manufactured by laminating and pressing the dielectric green sheet having the internal electrode pattern obtained as described above so that the internal electrode layers 2 could be alternately connected to the outside.

  Then, after the obtained laminate was separated into pieces, a debide treatment for burning organic substances such as a resin binder and a plasticizer was performed in a non-oxidizing atmosphere, followed by firing in a reducing atmosphere at 1300 ° C.

  At this time, it is preferable to select an optimum firing temperature as appropriate within the range of 1140 ° C. to 1360 ° C. In the sample shown in Example 1, a dense sintered body within the range of 1240 to 1320 ° C. And good characteristics were obtained. The thickness of the dielectric layer 1 of the multilayer ceramic capacitor thus produced was 10 μm.

  Next, a multilayer ceramic capacitor was obtained by forming a pair of external electrodes 4 on both ends of the fired capacitor element body 3 using a copper electrode paste.

  The characteristics of the multilayer ceramic capacitor produced as described above were evaluated. In this characteristic evaluation, temperature characteristics and dielectric constant were measured. For these measurements, an LCR meter was used to obtain the capacitance of the measurement sample at room temperature under the conditions of 1 kHz and signal voltage of 1 Vrms. From the electrode area, the inter-electrode distance and the number of layers of the alternately facing internal electrode layers 2 The dielectric constant at that time was obtained by calculation.

  Similarly, the rate of change in capacitance with respect to each temperature was evaluated with 25 ° C. as a reference. The evaluation results of the temperature characteristics at that time are shown in FIG.

  For reliability, a high-temperature load life test was conducted at 150 ° C.-100 kV for 1000 hours. This high-temperature load life test was judged by the short-circuit rate of the multilayer ceramic capacitor and the decrease in capacitance after 1000 hours had passed.

  The evaluation results of the multilayer ceramic capacitor thus fabricated are shown in (Table 1).

  Here, in this example, regarding the temperature characteristics of the capacitance, the case where the X8R temperature characteristics are satisfied with a margin with respect to the standard (ΔC / C ≦ ± 14.5%) is ○, and the case where the standard width is just below (14 .5% <ΔC / C ≦ ± 15.0%) is indicated by Δ, and when the standard is not satisfied (15.0% <ΔC / C) is indicated by ×.

  As for the reliability test, 100 samples were tested to evaluate the short-circuit rate and the decrease in capacitance after 1000 hours. The short-circuit rate was within 5%, and the decrease in capacitance was- The case where it was within 10% and both of these conditions were satisfied was indicated as ◯.

  From these results, it can be seen that the multilayer ceramic capacitor shown in Example 1 maintains a high dielectric constant, satisfies the X8R characteristics, and has a dense crystal structure, and thus has excellent reliability characteristics. .

  Furthermore, based on the same procedure as described above, a multilayer ceramic capacitor having a composition as shown in (Table 2) was produced.

  Here, in particular, when the BET value of the dielectric ceramic composition after the dispersion of the dielectric slurry is normalized to 100, the BET value of the main component barium titanate is pulverized and dispersed so as to be larger than 100. In the case of using a medium agitating mill, when pulverizing and dispersing so as to be smaller than 100, the medium is not used, and the dielectric ceramic composition in the dielectric slurry is crushed by colliding with each other. Made. The ratio of the BET values of the dielectric ceramic composition thus produced is shown in (Table 2).

  Thereafter, a multilayer ceramic capacitor was produced by the same method as described above, and the same evaluation was performed. The results are shown in (Table 2).

  From the results of (Table 2), in Examples 2 to 13 of the present invention, the results of the temperature characteristics, dielectric constant and reliability test of X8R are good, indicating that it is an excellent multilayer ceramic capacitor.

  On the other hand, Comparative Example 1 has good dielectric constant and temperature characteristics, but has a problem in the evaluation result of the reliability test. This is considered to be because in the region where the ratio of the BET value is 100 or less, the dielectric ceramic composition cannot obtain a dense sintered body due to the difficulty of sintering. Moreover, the comparative example 2 has a result that a dielectric constant becomes low and a temperature characteristic is also bad. This is presumably because the raw particles of barium titanate were destroyed and the crystallinity was greatly reduced due to excessive grinding.

  In addition, Comparative Example 3, Comparative Example 4 and Comparative Example 5 are difficult to sinter in any case, and a dense sintered body cannot be obtained in an appropriate firing temperature range, causing problems in terms of reliability. It was. In particular, in Comparative Example 5, sintering could not be performed. Thus, when the addition amount of rare earth elements increased, the sinterability deteriorated, and when a certain amount or more of MgO was added, there was a tendency to have very difficult sintering characteristics.

  Further, Comparative Example 6, Comparative Example 7, Comparative Example 8 and Comparative Example 9 showed high dielectric constants, but the temperature characteristics were very poor. This is thought to be because the grain growth of barium titanate could not be suppressed because the amount of rare earth oxide constituting the core-shell structure was insufficient.

  Further, in Comparative Example 10, although the temperature characteristics and reliability were good, the dielectric constant was low. Furthermore, even when the rare earth oxides A and B were added alone, good electrical characteristics could not be realized.

  As described above, the multilayer ceramic capacitor produced using the dielectric ceramic composition shown in the present example satisfies the X8R characteristic and has excellent reliability while maintaining a high dielectric constant. A composition and a multilayer ceramic capacitor using the composition could be realized.

  The dielectric ceramic composition according to the present invention and the multilayer ceramic capacitor using the dielectric ceramic composition are prepared by appropriately adjusting the additive amounts of Mg and two kinds of rare earth metals as accessory components, and performing an appropriate pulverization treatment thereto. As a ceramic electronic component that can realize a dielectric ceramic composition that satisfies the X8R characteristic while maintaining a high dielectric constant and can realize excellent reliability, and a multilayer ceramic capacitor using the dielectric ceramic composition, and can be used in a high temperature environment Useful.

1 is a partially cutaway perspective view of a multilayer ceramic capacitor according to a first embodiment of the present invention. Conceptual diagram of the crystal structure of the dielectric ceramic composition constituting the dielectric layer Characteristic diagram showing temperature characteristics of the same multilayer ceramic capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dielectric layer 2 Internal electrode layer 3 Capacitor element body 4 External electrode 5 Core layer 6 Shell layer 7 Grain boundary layer

Claims (3)

With respect to 100 mol of barium titanate as the main component, at least magnesium as an auxiliary component is 0.5 to 2.0 mol in terms of MgO, rare earth metal A (at least one selected from Dy, Ho, Y) and rare earth A dielectric ceramic composition in which the sum of metals B (at least one selected from Yb, Er, and Tm) is 2.0 to 5.0 moles in terms of oxide, and the BET of this dielectric ceramic composition A dielectric ceramic composition having a BET value of 100 to 150 when the BET value of the barium titanate raw material powder is 100. The dielectric ceramic composition according to claim 1, wherein the Ba / Ti ratio of barium titanate is 0.990 to 1.005. A multilayer ceramic capacitor having a capacitor element body in which dielectric layers and internal electrode layers are alternately stacked, wherein the dielectric layer is at least magnesium as an auxiliary component in terms of MgO with respect to 100 moles of barium titanate. 0.5-2.0 mol, the total of rare earth metal A (at least one selected from Dy, Ho, Y) and rare earth metal B (at least one selected from Yb, Er, Tm) as oxide The dielectric ceramic composition is 2.0 to 5.0 moles when the BET value of the dielectric ceramic composition is 100, when the BET value in the barium titanate raw material powder is 100. A multilayer ceramic capacitor having a dielectric layer using a dielectric ceramic composition having a BET value of 100 to 150.

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