JP5488118B2 - Dielectric porcelain composition and electronic component - Google Patents

Description

  The present invention relates to a dielectric ceramic composition and an electronic component having the dielectric ceramic composition in a dielectric layer. More specifically, the dielectric ceramic composition is suitably used for medium-high voltage applications having a high rated voltage (for example, 100 V or more). The present invention relates to a body porcelain composition and an electronic component.

  In recent years, there has been a high demand for downsizing of electronic components due to higher density of electronic circuits, and the use of multilayer ceramic capacitors has rapidly increased in size and capacity, and applications have been expanded.

  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.

  In capacitors used for such applications, thinning and multilayering of dielectric layers are being promoted. However, if the particle diameter of the dielectric particles is reduced in order to reduce the thickness of the dielectric layer, there is a problem that a desired characteristic cannot be obtained because the relative permittivity is lowered.

  Furthermore, when used at a high rated voltage as described above, it will be used under a high electric field strength, but as the electric field strength increases, the relative dielectric constant decreases, and as a result, in the usage environment. There was a problem that the effective capacity would decrease.

For example, Patent Document 1 includes, as a main component, barium titanate represented by the general formula: ABO ₃ + aR + bM (R is a compound containing an element such as La, and M is a compound containing an element such as Mn). A reduction-resistant dielectric ceramic composed of a solid solution and a sintering aid is disclosed. This reduction-resistant dielectric ceramic is further described as containing X (Zr, Hf) O ₃ (X is at least one selected from Ba, Sr and Ca). This Patent Document 1 provides a reduction-resistant dielectric ceramic that has low loss and heat generation when used under high frequency, high voltage, or large current, and that exhibits stable insulation resistance at AC high-temperature load or DC high-temperature load. The purpose is to do.

In addition, Patent Document 2 discloses that the main component represented by (1-a-b-c-d-t) BaTiO ₃ + aCaTiO ₃ + b {(1-x) BaZrO ₃ + xSrZrO ₃ } + cMgO + dMnO + tRe ₂ O ₃ is sintered. A non-reducing dielectric ceramic composition comprising an auxiliary agent is disclosed. According to Patent Document 2, according to this dielectric ceramic composition, while maintaining a high relative dielectric constant and a small dielectric loss tangent, it has excellent relative dielectric constant aging characteristics, a large CR product, and a capacitance temperature change. It is stated that it can be made smaller.

  However, the thicknesses of the dielectric layers of the capacitors disclosed in Patent Document 1 and Patent Document 2 are large, and cannot cope with the thinning. Moreover, nothing is described about the relative dielectric constant in an environment where the electric field strength is high, and the effective capacity is unknown.

JP 2002-50536 A JP-A-4-264306

  The present invention has been made in view of such a situation, and even when the dielectric layer is thinned, the dielectric has a high relative dielectric constant under a high electric field strength and has good temperature characteristics and reliability. It is an object of the present invention to provide a porcelain composition and an electronic component having the dielectric porcelain composition as a dielectric layer.

In order to achieve the above object, the dielectric ceramic composition according to the present invention comprises:
Contains barium titanate as the main component,
For 100 moles of barium titanate,
A component consisting of barium zirconate and strontium zirconate, in terms of BaZrO ₃ and SrZrO ₃ , 5 to 15 mol,
Mg oxide, 3 to 5 mol in terms of MgO,
R oxide (wherein R is at least selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) 1) in terms of R ₂ O ₃ , 4-6 mol,
The oxide of at least one element selected from the group consisting of Mn, Cr, Co and Fe is 0.5 to 1.5 mol in terms of MnO, Cr ₂ O ₃ , Co ₃ O ₄ and Fe ₂ O ₃ ,
A compound containing Si, containing 2.5 to 4 mol in terms of Si,
When the component is represented as (1-x) BaZrO ₃ + xSrZrO ₃ , the x is 0.4 to 0.9.

  In the present invention, the specific composition and content described above, and in particular, by setting the molar ratio of barium zirconate and strontium zirconate to a specific range, the dielectric constant under high electric field strength is high, and the temperature is good. A dielectric ceramic composition having characteristics and reliability is obtained.

  Preferably, the average particle diameter of the dielectric particles constituting the dielectric ceramic composition is 0.10 to 0.30 μm. By doing in this way, the effect mentioned above can further be heightened.

  The electronic component which concerns on this invention is an electronic component which has a dielectric material layer comprised from the dielectric ceramic composition in any one of said, and an electrode layer.

  The electronic component according to the present invention is not particularly limited, and examples thereof include a multilayer ceramic capacitor, a piezoelectric element, a chip inductor, a chip varistor, a chip thermistor, a chip resistor, 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 a graph showing the capacity-temperature characteristics of samples according to examples and comparative examples of the present invention. FIG. 3 is a graph showing the relative dielectric constant when a DC voltage is applied when the ratio of BaZrO ₃ and SrZrO ₃ or CaZrO ₃ is changed.

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

Multilayer ceramic capacitor 1
As shown in FIG. 1, a multilayer ceramic capacitor 1 as an example of a multilayer ceramic electronic component includes a capacitor element body 10 having a configuration in which dielectric layers 2 and internal electrode layers 3 are alternately stacked. 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 shape of the capacitor element body 10 is not particularly limited, but is usually a rectangular parallelepiped as shown in FIG. 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 is composed of barium titanate as a main component, components composed of barium zirconate and strontium zirconate as subcomponents, an oxide of Mg, an oxide of R, Mn, Cr, It has an oxide of at least one element selected from Co and Fe, and a compound containing Si.

The barium titanate contained as the main component is represented by, for example, the composition formula Ba _m TiO _{2 + m} , _m in the composition formula is 0.990 <m <1.010, and the ratio of Ba and Ti is Those having 0.990 <Ba / Ti <1.010 can be used.

The content of the component (BaZrO ₃ + SrZrO ₃ ) composed of barium zirconate and strontium zirconate is 5 to 15 mol, preferably 8 to 15 in terms of BaZrO ₃ and SrZrO _{3 with} respect to 100 mol of barium titanate. 12 moles. If the content of the component is too small, the temperature characteristics tend to deteriorate, while if too large, the temperature characteristics deteriorate and the high temperature load life tends to decrease.

Further, when the component is represented as (1-x) BaZrO ₃ + xSrZrO ₃ , x indicating the molar ratio of SrZrO ₃ is 0.4 to 0.9, preferably 0.45 to 0.8. By setting x in the above range, that is, by making the ratio of BaZrO ₃ and SrZrO ₃ a specific range, a high dielectric constant is exhibited even under high electric field strength, and good temperature characteristics and reliability (high temperature Load life).

If x is too small, that is, if the molar ratio of SrZrO ₃ is too small, the relative dielectric constant tends to decrease under high electric field strength. On the other hand, if x is too large, that is, if the molar ratio of SrZrO ₃ is too large, although the relative dielectric constant under high electric field strength is good, the temperature characteristics tend to deteriorate.

In addition, it is preferable that this component does not contain CaZrO ₃ . When CaZrO ₃ is included, the specific dielectric constant under high electric field strength is slightly deteriorated, and the temperature characteristics tend to be deteriorated. Furthermore, when CaZrO ₃ is contained, dielectric particles of the dielectric ceramic composition are likely to grow, so that it cannot cope with thinning and the reliability tends to be lowered.

  The content of Mg oxide is 3 to 5 mol, preferably 3.5 to 4.5 mol in terms of MgO with respect to 100 mol of barium titanate. If the content of Mg oxide is too small or too large, the relative dielectric constant tends to decrease under high electric field strength.

The content of the oxide of R is 4 to 6 mol, preferably 4.5 to 5.5 mol in terms of R ₂ O _{3 with} respect to 100 mol of barium titanate. When the content of the R oxide is too small, the temperature characteristics deteriorate and the high temperature load life tends to decrease. On the other hand, if the amount is too large, the high temperature load life tends to decrease. The R element constituting the R oxide is at least selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Among these, at least one selected from Gd, Tb, Eu, Y, La, and Ce is preferable, and Gd is particularly preferable.

The content of oxides of Mn, Cr, Co and Fe is 0.5 to 1.5 in terms of MnO, Cr ₂ O ₃ , Co ₃ O ₄ or Fe ₂ O _{3 with} respect to 100 mol of barium titanate. Mol, preferably 0.8 to 1.2 mol. If the content of these oxides is too small, the high temperature load life tends to be reduced. On the other hand, if the amount is too large, the relative permittivity and the relative permittivity under a high electric field strength decrease, the temperature characteristics deteriorate, and the high-temperature load life tends to rapidly decrease. In addition, it is preferable to use the oxide of Mn from the point that the improvement effect of a characteristic is large among each said oxide.

Content of the compound containing Si is 2.5-4 mol in conversion of Si with respect to 100 mol of barium titanate, Preferably it is 3-3.5 mol. When the content of the compound containing Si is too small, the sinterability is deteriorated and desired characteristics tend not to be obtained. On the other hand, if the amount is too large, excessive firing occurs, and desired characteristics tend not to be obtained. Although not particularly restricted but includes compounds containing Si, from the viewpoint that a large effect of improving the characteristics, it is preferable to use SiO _2.

  In the present embodiment, the dielectric ceramic composition constituting the dielectric layer 2 has dielectric particles. At least some of these particles have a so-called core-shell structure. The core portion is substantially made of barium titanate, and the shell portion has a configuration in which the subcomponent element is dissolved in barium titanate.

  Barium titanate in the core part has a high dielectric constant because it maintains ferroelectricity, but when the electric field strength applied from the outside increases, the polarization of the core part, which is a ferroelectric substance, changes the direction of the electric field. It is constrained by this, and it is difficult for the polarization to easily reverse. Therefore, it is considered that the relative permittivity is lowered by this influence.

  Therefore, in the present embodiment, the presence state of subcomponents in the shell portion, in particular, the presence state of components composed of barium zirconate and strontium zirconate is controlled, and the crystal structure of the shell portion is changed to easily reverse the polarization. By doing so, the dielectric constant can be kept high even under high electric field strength.

  It has been clarified by the present inventors that the relative dielectric constant exhibited by the dielectric ceramic composition converges to a substantially constant value as the electric field strength increases (for example, 15 V / μm or more). However, a dielectric ceramic composition exhibiting a high relative dielectric constant in a state where an electric field is not applied (for example, a state where a DC voltage is not applied) exhibits a high relative dielectric constant even under a high electric field strength. Not exclusively.

  Therefore, an electronic component having a dielectric layer composed of a dielectric ceramic composition having a high relative dielectric constant under a high electric field strength is high regardless of the relative dielectric constant in a state where no electric field is applied. A sufficient effective capacity can be secured even under electric field strength.

  The average particle diameter of the dielectric particles contained in the dielectric layer 2 is measured as follows. That is, the capacitor element body 10 is cut in the stacking direction of the dielectric layer 2 and the internal electrode layer 3, the area of the dielectric particles is measured in the cross section, the diameter is calculated as the equivalent circle diameter, and a value obtained by multiplying by 1.5 The particle size. In the present embodiment, 150 or more dielectric particles are measured, and the value at which the accumulation is 50% from the cumulative frequency distribution of the obtained particle diameter is defined as the average particle diameter (unit: μm).

  In the present embodiment, the average particle diameter of the dielectric particles may be determined according to the thickness of the dielectric layer 2 and the like, but is preferably 0.10 to 0.30 μm, more preferably 0.20 to 0.00. 30 μm. By setting the average particle size in the above range, sufficient reliability can be ensured even when the dielectric layer is thinned.

  The thickness of the dielectric layer 2 is not particularly limited, but is preferably about 1 to 5 μm per layer in order to meet the demand for thinning.

Internal electrode layer 3
The conductive material contained in the internal electrode layer 3 is not particularly limited, but a relatively inexpensive base metal can be used because the constituent material of the dielectric layer 2 has reduction resistance. As the base metal used as the conductive material, Ni or Ni alloy is preferable. The Ni alloy is preferably an alloy of Ni and one or more elements selected from Mn, Cr, Co and Al, and the Ni content in the alloy is preferably 95% by weight or more. In addition, in Ni or Ni alloy, various trace components, such as P, may be contained about 0.1 wt% 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.

External electrode 4
The conductive material contained in the external electrode 4 is not particularly limited, but in the present invention, inexpensive Ni, Cu, and alloys thereof can be used. What is necessary is just to determine the thickness of the external electrode 4 suitably according to a use etc.

Manufacturing Method of Multilayer Ceramic Capacitor 1 The multilayer ceramic capacitor 1 of the present embodiment is the same as a conventional multilayer ceramic capacitor. After producing a green chip by a normal printing method or a sheet method using a paste and firing it, It is manufactured by printing or transferring an external electrode and firing. Hereinafter, the manufacturing method will be specifically described.

  First, a dielectric material (dielectric ceramic composition powder) contained in the dielectric layer paste is prepared, and this 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 material and an organic vehicle, or may be a water-based paint.

  As the dielectric material, the above-mentioned main component and subcomponent oxides, mixtures thereof, and composite oxides can be used. In addition, various compounds that become the above oxides or composite oxides by firing, such as carbonic acid, can be used. A salt, an oxalate salt, a nitrate salt, a hydroxide, an organometallic compound, or the like can be selected as appropriate and used in combination.

For example, as a raw material for barium titanate, BaTiO ₃ powder may be used, or BaCO ₃ powder and TiO ₂ powder may be used. Further, as a raw material component consisting of barium zirconate and strontium _zirconate, it may be used Ba _1-x Sr _x ZrO ₃ powder may be used BaZrO ₃ powder and SrZrO ₃ powder.

  Barium titanate powder as a raw material of the main component is produced by various liquid phase methods (for example, oxalate method, hydrothermal synthesis method, alkoxide method, sol-gel method, etc.) in addition to the so-called solid phase method, Those produced by various methods can be used.

  The particle size of the barium titanate powder is preferably 150 to 250 nm. Even when the dielectric layer is thinned using a raw material having such a fine particle diameter, the effects of the present invention can be obtained.

  The auxiliary component raw material may be added to the main component raw material without calcining, but it is preferable to calcine only the sub component raw material and use the calcined raw material as the main component. Add to raw material to make dielectric raw material. Further, it is more preferable not to calcine the component consisting of barium zirconate and strontium zirconate, and calcining the raw materials of subcomponents other than the component.

  What is necessary is just to determine content of each compound in a dielectric raw material so that it may become a composition of the above-mentioned dielectric ceramic composition after baking.

  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, toluene, 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 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 1-5 weight% of binders, for example, about 10-50 weight% of binders. 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 weight 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 temperature rising rate is preferably 5 to 300 ° C./hour, the holding temperature is preferably 180 to 400 ° C., and the temperature holding time is preferably 0.5 to 24 hours.

  The green chip is preferably fired under the following conditions.

The temperature rising rate is preferably 50 to 500 ° C./hour, the temperature holding time is preferably 0.5 to 8 hours, and the cooling rate is preferably 50 to 500 ° C./hour. Further, the firing atmosphere is preferably a reducing atmosphere, and as the atmosphere gas, for example, a mixed gas of N ₂ and H ₂ can be used by humidification.

  The holding temperature during firing is preferably 1000 to 1400 ° C, more preferably 1100 to 1300 ° C, and the holding time is preferably 0.5 to 8 hours, more preferably 1 to 3 hours. If the holding temperature is lower than the above range, the densification becomes insufficient, and if it exceeds the above range, the electrode temperature is interrupted due to abnormal sintering of the internal electrode layer, or the capacity temperature characteristics deteriorate due to diffusion of the constituent material of the internal electrode layer. Further, reduction of the dielectric ceramic composition is likely to occur.

The oxygen partial pressure during firing may be appropriately determined according to the type of the conductive material in the internal electrode layer paste, but when a base metal such as Ni or Ni alloy is used as the conductive material, the oxygen content in the firing atmosphere The pressure is preferably 10 ⁻¹⁴ to 10 ⁻¹⁰ MPa. When the oxygen partial pressure is less than the above range, the conductive material of the internal electrode layer may be abnormally sintered and may be interrupted. Further, when the oxygen partial pressure exceeds the above range, the internal electrode layer tends to be oxidized.

  After firing in a reducing atmosphere, the capacitor element body is preferably annealed. Annealing is a process for re-oxidizing the dielectric layer, and this can significantly increase the IR lifetime, thereby improving the reliability.

The oxygen partial pressure in the annealing atmosphere is preferably 10 ⁻⁹ to 10 ⁻⁵ MPa. If the oxygen partial pressure is less than the above range, reoxidation of the dielectric layer is difficult, and if it exceeds the above range, oxidation of the internal electrode layer tends to proceed.

  The holding temperature at the time of annealing is preferably 1100 ° C. or less, particularly 500 to 1100 ° C. When the holding temperature is lower than the above range, the dielectric layer is not sufficiently oxidized, so that the insulation resistance is low and the life of the insulation resistance (high temperature load life) tends to be shortened. On the other hand, when the holding temperature exceeds the above range, not only the internal electrode layer is oxidized and the capacity is lowered, but also the internal electrode layer reacts with the dielectric substrate, the capacity temperature characteristic is deteriorated, and the insulation resistance is lowered. In addition, the life of the insulation resistance is likely to decrease. Note that annealing may be composed of only a temperature raising process and a temperature lowering process. That is, the temperature holding time may be zero. In this case, the holding temperature is synonymous with the maximum temperature.

As other annealing conditions, the temperature holding time is preferably 0 to 20 hours, and the temperature drop rate is preferably 50 to 500 ° C./hour. Further, as the annealing atmosphere gas, for example, N ₂ or N ₂ + H ₂ O gas is preferably used.

In the above-described binder removal processing, firing and annealing, for example, a wetter or the like may be used to wet the N ₂ gas or mixed gas. In this case, the water temperature is preferably about 5 to 75 ° C.

  The binder removal treatment, firing and annealing may be performed continuously or independently.

  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.

  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 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.

  For example, in the above-described embodiment, the multilayer ceramic capacitor is exemplified as the electronic component according to the present invention. However, the electronic component according to the present invention is not limited to the multilayer ceramic capacitor, and has a dielectric layer having the above configuration. Anything is fine.

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

Examples 1-15, Comparative Examples 1-14
First, BaTiO ₃ powder is used as a main component raw material, and BaZrO ₃ (hereinafter also referred to as BZ), SrZrO ₃ (hereinafter also referred to as SZ), MgCO ₃ , Gd ₂ O ₃ , MnO and SiO as subcomponent raw materials. ₂ were prepared respectively. Among the subcomponent raw materials, BZ and SZ were not calcined, but MgCO ₃ , Gd ₂ O ₃ , MnO and SiO ₂ were calcined. Next, the main component raw material prepared above, BZ and SZ, and the calcined raw material were wet pulverized with a ball mill for 15 hours and dried to obtain a dielectric raw material. The addition amount of each subcomponent, with respect to BaTiO ₃ 100 moles of the main component, and the amount shown in Table 1. The amount shown in Table 1 is the amount in terms of complex oxide or each oxide. In addition, MgCO ₃ is contained in the dielectric ceramic composition as MgO after firing.

In the samples of Comparative Examples 2 and 3, CaZrO ₃ (hereinafter also referred to as CZ) was used instead of SrZrO ₃ .

  Next, the obtained dielectric material: 100 parts by weight, polyvinyl butyral resin: 10 parts by weight, dibutyl phthalate (DOP) as a plasticizer: 5 parts by weight, and alcohol as a solvent: 100 parts by weight with a ball mill The mixture was made into a paste to obtain a dielectric layer paste.

  In addition to the above, Ni particles: 44.6 parts by weight, terpineol: 52 parts by weight, ethyl cellulose: 3 parts by weight, and benzotriazole: 0.4 parts by weight are kneaded with three rolls to obtain a slurry. To prepare an internal electrode layer paste.

  And the green sheet was formed on PET film using the paste for dielectric material layers produced above. 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 laminated body, and the green laminated body was cut into a predetermined size to obtain a green chip.

  Next, the obtained green chip was subjected to binder removal treatment, firing and annealing under the following conditions to obtain a multilayer ceramic fired body.

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

Firing conditions are: temperature rising rate: 200 ° C./hour, holding temperature: 1200 ° C., temperature holding time: 2 hours, cooling rate: 200 ° C./hour, atmospheric gas: N ₂ + H ₂ + H ₂ O mixed gas (oxygen partial pressure) : 10 ⁻¹² MPa).

The annealing conditions are: temperature rising rate: 200 ° C./hour, holding temperature: 1050 ° C., temperature holding time: 2 hours, cooling rate: 200 ° C./hour, atmospheric gas: N ₂ + H ₂ O mixed gas (oxygen partial pressure: 10 ⁻⁷ MPa). A wetter was used for humidifying the atmospheric gas during firing and annealing.

  Next, after polishing the end face of the obtained multilayer ceramic fired body by sand blasting, In-Ga was applied as an external electrode to obtain a sample of the multilayer ceramic capacitor 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 3.0 μm, the thickness of the internal electrode layer is 1.5 μm, and the dielectric sandwiched between the internal electrode layers The number of layers was 10. In this example, as shown in Table 1, a plurality of samples in which the content of each subcomponent was changed were produced.

  For each of the obtained capacitor samples, the relative dielectric constant (εr) at the time of applying a DC voltage, the rate of change in capacitance temperature, the high temperature load life, and the average particle diameter of the dielectric particles were measured by the following methods.

Relative permittivity εr when DC voltage (DC-bias) is applied
Using a digital LCR meter (YHP 4284A) with a DC voltage applied to both ends of the capacitor sample so that the electric field strength is 20 V / μm, a frequency of 1 kHz, input signal level (measurement voltage) A signal of 1 Vrms was input, and the capacitance C at 25 ° C. was measured. Then, the relative dielectric constant εr (no unit) at the time of applying the DC voltage was calculated based on the thickness of the dielectric layer, the effective electrode area, and the capacitance C obtained as a result of the measurement. In this example, the average value of values calculated using 10 capacitor samples was used as the relative dielectric constant when a DC voltage was applied. In this example, 300 or more was considered good. The results are shown in Table 2.

  For reference, the relative dielectric constant was measured in the same manner as described above with no DC voltage applied. This dielectric constant is also shown in Table 2.

Capacity temperature characteristics (TC)
The capacitance at −55 ° C. to 125 ° C. was measured for the capacitor sample, and the rate of change relative to the capacitance at the reference temperature (25 ° C.) was calculated. It is preferable that the rate of change is small, and those in the range of + 22% to −33% are good (X7T characteristics). The results are shown in Table 2. Moreover, the graph of the capacity-temperature characteristic about Example 3 and Comparative Examples 1-4 is shown in FIG.

The high temperature load life of the capacitor sample was evaluated by holding a DC voltage applied at 200 ° C. under an electric field of 70 V / μm and measuring the breakdown time. In this example, Weibull analysis was performed on the breakdown time, and the time from the start of application until the insulation resistance dropped by an order of magnitude was defined as the lifetime. Further, this high temperature load life was carried out for 10 capacitor samples. The evaluation criteria were good for 1.0 hour or longer. The results are shown in Table 2.

A capacitor sample having an average particle size of dielectric particles was cut, the cut surface was observed with a scanning electron microscope (SEM), and an 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 particle diameter was calculated by converting the calculated area of the dielectric particles into an equivalent circle diameter. The average value of the obtained particle diameters was defined as the average particle diameter. The particle diameter was calculated for 150 dielectric particles. The average particle diameter was 0.10 to 0.30 μm. The results are shown in Table 2.

From Tables 1 and 2, in the component represented by (1-x) BaZrO ₃ + xSrZrO ₃ , when x = 0, that is, when the component is composed only of BaZrO ₃ (Comparative Example 1), the DC voltage applied It was confirmed that the relative dielectric constant was low. In addition, when x = 1, that is, when the component is composed only of SrZrO ₃ (Comparative Example 4), it was confirmed that the temperature characteristics were deteriorated although the relative dielectric constant when a DC voltage was applied was high.

In addition, when CaZrO ₃ is used instead of SrZrO ₃ (Comparative Examples 2 and 3), in addition to the low relative dielectric constant when a DC voltage is applied, dielectric particles grow, resulting in a result. It was confirmed that the temperature characteristics and the high temperature load life were deteriorated.

Further, it is visually confirmed from FIG. 2 that when x = 1 (Comparative Example 4) and when CaZrO ₃ is contained (Comparative Examples 2 and 3), the temperature characteristics deteriorate and the X7T characteristics are not satisfied. did it.

  Furthermore, when the content of subcomponents is outside the range of the present invention (Comparative Examples 5 to 14), at least one of the relative permittivity, the temperature characteristics, and the high temperature load life when a DC voltage is applied is deteriorated. Was confirmed.

  On the other hand, when the value of x and the content of subcomponents are within the scope of the present invention (Examples 1 to 15), all of the relative permittivity, the temperature characteristics, and the high temperature load life when a DC voltage is applied It was confirmed that it was good.

In addition, it can be confirmed from FIG. 3 that the relative permittivity when a DC voltage is applied is greatly improved by setting the ratio of BaZrO ₃ and SrZrO ₃ to a specific ratio (SZ (0 ≦ x ≦ 1)). It was. On the other hand, it was confirmed that even when the ratio of BaZrO ₃ and CaZrO ₃ was changed (CZ (0 ≦ x ≦ 1)), the relative dielectric constant when a DC voltage was applied was not improved so much.

  The relative dielectric constant when the DC voltage is applied tends to decrease as the applied DC voltage increases. However, the relative dielectric constant of each sample converges to a substantially constant value under an electric field strength such as 20 V / μm in this embodiment or under a higher electric field strength. Therefore, even under a higher electric field strength than the present example, the sample according to the example of the present invention has a higher relative dielectric constant when a DC voltage is applied than the sample according to the comparative example.

  As is clear from the relative permittivity when no DC voltage is applied as shown in Table 2, the relative permittivity when no DC voltage is applied, and the relative permittivity when the DC voltage is applied, Is not relevant at all.

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

Claims (3)

Contains barium titanate as the main component,
For 100 moles of barium titanate,
A component consisting of barium zirconate and strontium zirconate, in terms of BaZrO ₃ and SrZrO ₃ , 5 to 15 mol,
Mg oxide, 3 to 5 mol in terms of MgO,
4 to 6 mol of an oxide of R (where R is Gd) in terms of Gd ₂ O ₃ ,
Mn oxide , 0.5 to 1.5 mol in terms of MnO ,
A compound containing Si, containing 2.5 to 4 mol in terms of Si,
When the component is represented as (1-x) BaZrO ₃ + xSrZrO ₃ , the x is 0.4 to 0.9.   The dielectric ceramic composition according to claim 1, wherein an average particle diameter of dielectric particles constituting the dielectric ceramic composition is 0.10 to 0.30 μm.   The electronic component which has a dielectric material layer and electrode layer comprised from the dielectric material ceramic composition of Claim 1 or 2.

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