JP2013211398A - Multilayer ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer ceramic capacitor that has high relative dielectric constant when the thickness is reduced, and has the electrostatic capacity change rate that satisfies a range of -15% to +15% in an operating temperature range of -55 to 85°C.SOLUTION: A multilayer ceramic capacitor includes a dielectric layer having a BaTiO3-based perovskite compound as a main component. Dielectric particles substantially do not include a shell structure; the capacitance change rate ΔC at 85°C of the multilayer ceramic capacitor is 15% or more in a measured AC electric field of 0.05 Vrms/μm or less; and ΔC is in a range of -15% to +15% in a measured AC electric field of 0.2 Vrms/μm or more.

Description

  The present invention relates to a multilayer ceramic capacitor.

  Multilayer ceramic capacitors are widely used as small-sized, large-capacity, high-reliability electronic components, and the number used in one electronic device is also large. Multilayer ceramic capacitors are usually laminated by a sheet method or a printing method using an internal electrode layer paste and a dielectric layer paste, and the internal electrode layer and the dielectric layer in the multilayer body are simultaneously formed. Manufactured by firing.

  In recent years, along with the downsizing and high performance of electronic devices, further downsizing and high capacity of multilayer ceramic capacitors used in the electronic devices are being promoted. In order to realize such downsizing and high capacity, development of dielectric ceramics suitable for thinning and high stacking of dielectric layers is required.

  For example, Patent Document 1 describes a dielectric ceramic having a core-shell structure and a Curie temperature of 80 to 90 ° C. However, in the dielectric ceramic described in Patent Document 1, the relative dielectric constant is about 4000 at the maximum, and further improvement of the relative dielectric constant is demanded. In addition, the dielectric ceramic described in Patent Document 2 describes a dielectric ceramic composition having a high relative dielectric constant even when the interlayer thickness is reduced to about 1.5 μm, but the temperature characteristics of the relative dielectric constant are poor. There was a problem.

JP 2008-239407 A JP 2005-187296 A

  The present invention has been made in view of such a situation, and an object thereof is to use a dielectric ceramic composition that is excellent in the stability of the temperature characteristics of the relative dielectric constant and has a high relative dielectric constant when thinned. It is to provide a multilayer ceramic capacitor having a high capacity density.

  The present inventor has been eager to develop a multilayer ceramic capacitor that is excellent in the stability of the temperature characteristic of the relative dielectric constant, has a high insulation resistance even when the layer is thinned, and has a high relative dielectric constant when the layer is thinned, and thus has a high capacitance density. As a result of investigation, the Curie temperature of the dielectric ceramic composition constituting the dielectric layer of the multilayer ceramic capacitor is set higher than the operating temperature range, and the electric field strength generated in the dielectric layer is increased, thereby increasing the operating temperature range. It was found that the capacity density was stably increased, and the present invention was completed.

  In order to achieve the above object, according to the present invention, in a multilayer ceramic capacitor in which dielectric layers and internal electrode layers are alternately stacked, an alternating electric field applied to the dielectric layer sandwiched between the internal electrode layers. When the strength is 0.05 Vrms / μm or less, the capacitance change rate ΔC at 85 ° C. with respect to 25 ° C. of the multilayer ceramic capacitor is 15% or more, and when the AC electric field strength is 0.2 Vrms / μm or more, A multilayer ceramic capacitor using a dielectric ceramic composition having a capacitance change rate ΔC in the range of −15% to + 15%.

  In the multilayer ceramic capacitor of the present invention, by reducing the thickness of the dielectric layer and increasing the electric field strength applied to the dielectric layer, the temperature characteristic of the relative dielectric constant is excellent in the operating temperature range, and the thickness is reduced. A multilayer ceramic capacitor having a high relative dielectric constant at the time of layering and thus a high capacitance density can be obtained.

  In the multilayer ceramic capacitor of the present invention, it is preferable that the dielectric layer has a thickness of 3 μm or less, more preferably 1 μm or less, and a portion where the number of particles in the dielectric layer thickness direction is 1 or 2. Thereby, the electric field strength applied to the dielectric particles contained in the dielectric layer can be increased, and the relative dielectric constant can be kept substantially constant at 4000 or more, 5000 or more, or 6000 or more.

  Further, the main component of the dielectric layer in the multilayer ceramic capacitor of the present invention is that when the BaTiO3 perovskite compound is represented by ABO3, A is at least one selected from Ba, Sr, and Ca, and B is Ti, Zr, Hf. And at least one selected from Sn. As a result, a multilayer ceramic capacitor having a high relative dielectric constant when thinned can be obtained.

Furthermore, the main component of the dielectric layer in the multilayer ceramic capacitor of the present invention is a dielectric ceramic composition represented by the general formula: (Ba _1-x Ca _x ) _m (Ti _1-y Zr _y ) _n O ₃ ,
In the general formula, 0 ≦ x ≦ 0.06, 0.01 ≦ y ≦ 0.08, and 0.950 ≦ m / n ≦ 1.050 are preferable. By using this dielectric ceramic composition, the dielectric particles do not substantially have a shell structure, and it is possible to increase the relative dielectric constant during thinning, and the relative dielectric constant is within the operating temperature range. Stable and high. Further, in addition to the above purpose, an effect of becoming a multilayer ceramic capacitor having excellent reliability can be obtained.

  Furthermore, the dielectric ceramic composition of the dielectric layer in the multilayer ceramic capacitor of the present invention preferably contains Mg as a first subcomponent and a rare earth element as a second subcomponent. The first subcomponent may contain 0.05 to 1.0 mol% of Mg in terms of MgO with respect to the main component. The second subcomponent includes at least one rare earth element selected from Y, Dy, Ho, Yb, Tb, Gd, Er, Sm, and Eu, and is 0.05 to It is good to include 4.0. By using this dielectric ceramic composition, it is possible to obtain a multilayer ceramic capacitor excellent in reliability in addition to the above-mentioned purpose and having a long deterioration time of insulation resistance under a direct current electric field.

  Furthermore, the dielectric ceramic composition of the dielectric layer in the multilayer ceramic capacitor of the present invention contains Mn or Cr as a third subcomponent and 0.02 to 2.0 mol% in terms of oxide with respect to the main component. good.

  With the dielectric ceramic of the present invention, it is possible to obtain a monolithic ceramic capacitor having good temperature characteristics of relative permittivity, high relative permittivity, and thus high capacity density. Furthermore, in addition to such effects, a highly reliable multilayer ceramic capacitor can be obtained.

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 shown in FIG. FIG. 3 is a graph showing temperature characteristics of dielectric constant in the multilayer ceramic capacitor according to the example of the present invention. 4A is an example of a TEM cross-sectional photograph of the dielectric layer in the multilayer ceramic capacitor according to the example of the present invention, and FIG. 4B is a diagram of the dielectric layer in the multilayer ceramic capacitor according to the comparative example of the present invention. It is an example of a TEM cross-sectional photograph.

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

(Multilayer ceramic capacitor)
As shown in FIG. 1, a multilayer ceramic capacitor 1 according to an embodiment of the present invention 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 capacitor element body 10. The outer shape and dimensions of the capacitor element body 10 are not particularly limited and can be appropriately set according to the application. Usually, the outer shape is substantially a rectangular parallelepiped shape, and the dimensions are vertical (0.15 to 5.6 [mm]). ) × width (0.2-5.0 [mm]) × thickness (0.1-1.9 [mm]).

  The internal electrode layers 3 are laminated so that one end of each internal electrode layer is alternately exposed on two opposing end faces of the capacitor element body 10. The pair of external electrodes 4 are formed on at least opposite end faces of the capacitor element body 10 and are connected to the exposed end portions of the alternately arranged internal electrode layers 3 to constitute a capacitor circuit.

  When the alternating electric field is applied through the external electrode 4 and the applied alternating electric field strength is 0.05 Vrms / μm or less, the dielectric ceramic composition constituting the dielectric layer 2 has the above multilayer ceramic capacitor. When the capacitance change rate (capacitance change rate) ΔC at 85 ° C. with respect to room temperature of 1 is 15% or more and the applied AC electric field strength is 0.2 Vrms / μm or more, It is assumed that ΔC is in the range of −15% to + 15%. Furthermore, the dielectric ceramic composition constituting the dielectric layer 2 has a Curie temperature set to a temperature higher than the upper limit of the use temperature range of the multilayer ceramic capacitor. The upper limit of the use temperature range here is 85 ° C. in the X5R standard, for example. Moreover, the room temperature here means 25 degreeC. By doing so, it is possible to obtain a multilayer ceramic capacitor having good stability of the temperature characteristics of the relative dielectric constant of the dielectric ceramic composition, and hence good capacitance temperature characteristics, and also having the dielectric ceramic composition. Since the dielectric constant can be increased, a multilayer ceramic capacitor having a high capacitance density can be obtained. In this case, the capacitance of the multilayer ceramic capacitor is simply referred to as capacitance or electrostatic capacitance, but both indicate the same thing.

The dielectric ceramic composition constituting the dielectric layer 2 is a BTZ-based dielectric ceramic composition having a perovskite structure represented by a composition formula (Ba _1-x Ca _x ) _m (Ti _1-y Zr _y ) _n O _3. It is good to have a thing as a main component. At this time, the amount of oxygen (O) may slightly change from the stoichiometric composition of the above formula. By adopting such a composition system, the Curie temperature of the dielectric ceramic composition can be easily controlled and the relative dielectric constant can be increased.

  In the above composition formula, x is preferably 0 ≦ x ≦ 0.06, more preferably 0 ≦ x ≦ 0.04. x represents the number of Ca atoms, and the phase transition point of the crystal, that is, the Curie temperature, can be shifted to a desired temperature by changing the symbol x, that is, the Ca / Ba ratio. As a result, the temperature characteristics of the dielectric constant and the height of the dielectric constant can be controlled. In this embodiment, it is good also as an aspect which does not contain x = 0, ie, Ca.

  In the above composition formula, y is preferably 0.01 ≦ y ≦ 0.08. More preferably, 0.02 ≦ y ≦ 0.08. y represents the number of Zr atoms. If Zr is too small, dielectric particles tend to have a core-shell structure, and if Zr is too large, it is difficult to set the Curie temperature of the dielectric ceramic above the operating temperature range. become.

  In the above composition formula, m / n is preferably 0.95 ≦ m / n ≦ 1.050, more preferably 0.99 ≦ m / n ≦ 1.01. By making m / n 0.95 or more, it is possible to prevent the formation of a semiconductor for firing in a reducing atmosphere, and by making m / n 1.050 or less, the firing temperature is not increased. A dense sintered body can be obtained.

  In the present embodiment, the Curie temperature Tc of the BTZ-based dielectric ceramic composition is set higher than the operating temperature range of the multilayer ceramic capacitor. For example, it is set higher than the operating temperature range (−55 ° C. to 85 ° C.) specified for X5R. That is, the Curie temperature Tc of the BTZ-based dielectric ceramic composition according to the present invention is preferably 85 ° C <Tc ≦ 110 ° C, and more preferably 90 ° C <Tc ≦ 110 ° C.

  The dielectric ceramic composition constituting the dielectric layer 2 of the present embodiment preferably contains a subcomponent in addition to the main component. In the present embodiment, it is preferable to include a first subcomponent and a second subcomponent. The first subcomponent is Mg oxide, and the second subcomponent is R (rare earth element).

  Mg oxide as the first subcomponent has an effect of suppressing grain growth of the main component raw material powder. The content of Mg oxide is preferably 0.05 to 1.0 mol in terms of MgO with respect to 100 mol of the main component.

  The rare earth element (R oxide) as the second subcomponent has the effect of improving the IR lifetime and the effect of flattening the capacity-temperature characteristic, that is, stabilizing the temperature characteristic of the dielectric constant of the dielectric ceramic. Show. R as the second subcomponent is preferably at least one selected from Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Yb. From the viewpoint of capacity-temperature characteristics, Tb and Y are preferable, and Y is more preferable. The content of the second subcomponent (R oxide) is 0.05 to 4 mol, preferably 0.1 to 2.0 mol in terms of element with respect to 100 mol of the main component.

  In the present invention, the content of the R oxide is not the molar ratio of the R oxide, but the molar ratio of the R element alone. That is, for example, when the oxide of Y is used as the oxide of R, the content of the oxide of R is 1 mol, the content of Y2 O3 is not 1 mol, but the content of Y element Means 1 mole.

  The dielectric ceramic composition constituting the dielectric layer 2 according to this embodiment preferably has a third subcomponent in addition to the main component and the first second subcomponent. In addition to achieving the above object by adding the third subcomponent, the effect of increasing the IR of the dielectric ceramic by promoting the sintering of the dielectric ceramic composition and the IR lifetime Further improving the effect. From such a viewpoint, the third subcomponent is preferably an oxide of Mn and / or Cr. The total content of Mn or Cr oxides is 0.02 to 2 mol, preferably 0.1 to 1 mol, more preferably 0.1 to 100 mol of the main component in terms of element. -0.5 mol.

  The dielectric ceramic composition constituting the dielectric layer 2 according to the present embodiment preferably contains a fourth subcomponent in addition to the main component and the first to third subcomponents. The fourth subcomponent is preferably an oxide containing Si. The fourth subcomponent mainly acts as a sintering aid, but has an effect of improving the defective rate of the initial insulation resistance when the layer is thinned. The content of the fourth subcomponent is 0.1 to 5 mol, preferably 0.5 to 4 mol, more preferably 0.5 to 4 mol in terms of oxide SiO2 with respect to 100 mol of the main component. 2 moles.

The oxide containing Si may be a simple oxide or a complex oxide. In the case of a complex oxide, (Ba, Ca) _n SiO _{2 + n} (where n = 0.8 to 1.2) is more preferable. Moreover, _{n in} (Ba, Ca) nSiO2 ₊ n is preferably 0 to 2, and more preferably 0.8 to 1.2. In the fourth subcomponent, the ratio of Ba and Ca is arbitrary, and only one of them may be contained.

  The dielectric ceramic composition constituting the dielectric layer 2 according to this embodiment preferably has a fifth subcomponent in addition to the main component and the first to fourth subcomponents. The fifth subcomponent is an oxide of at least one element selected from V, Mo, W, Ta and Nb. In addition to the object of the present invention, from the viewpoint of further improving the high temperature load life, Nb oxide and V oxide are preferable, and V oxide is more preferable. The content of the fifth subcomponent is preferably 0 to 0.2 mol in terms of each element with respect to 100 mol of the main component.

  The thickness of the dielectric layer 2 is such that the AC electric field strength applied to the dielectric layer 2 is 2.0 Vrms / μm or more in the circuit in which the multilayer ceramic capacitor according to the present invention is used as described above. Preferably, it is 3.0 μm or less per layer, more preferably 2.6 μm or less, and particularly when the layer is thinned to 1.0 μm or less, the number of dielectric particles in the stacking direction of the dielectric layer 2 is reduced. One or two locations are formed, and a high alternating electric field is applied to the dielectric particles when using the multilayer ceramic capacitor, which is preferable. The lower limit of the thickness is preferably thin from the viewpoint of increasing the applied AC electric field strength as long as insulation can be ensured, and is not particularly limited, but is, for example, about 0.5 μm. As shown in FIG. 2, the dielectric layer 2 includes dielectric particles 2a having no so-called core-shell structure, and the particle size of the dielectric particles 2a is preferably 0.1 to 0.5 μm. is there. The particle size of the dielectric particles 2 a is controlled so that 1 to 4 particles exist between the internal electrode layers 3 and 3. More preferably, the particle size of the dielectric particles 2 a is controlled so that one or two particles exist between the internal electrode layers 3 and 3. The number of dielectric particles existing in the stacking direction of the dielectric layer 2 can be reduced by increasing the particle size. As a result, an AC electric field can be reliably applied to the dielectric particles, and thus the dielectric constant of the dielectric particles 2a. The rate can be maintained high, and as a result, the capacitance density of the multilayer ceramic capacitor can be increased.

  The number of laminated dielectric layers 2 is not particularly limited, but is preferably 20 or more, more preferably 50 or more, and particularly preferably 100 or more. The upper limit of the number of stacked layers is not particularly limited, but is about 2000, for example.

  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. As the Ni alloy, an alloy of Ni and one or more elements selected from Mn, Cr, Co and Al is preferable, and the Ni content in the alloy is preferably 95% by mass or more. In addition, in Ni or Ni alloy, various trace components, such as P, may be contained about 0.1 mass% or less. The thickness of the internal electrode layer 3 may be appropriately determined according to the application and the like, but is usually 0.3 to 2.0 μm, and particularly preferably about 0.3 to 1.0 μm.

  The conductive material contained in the external electrode 4 is not particularly limited, but in the present embodiment, inexpensive Ni, Cu, and alloys thereof can be used. The thickness of the external electrode 4 may be appropriately determined according to the application and the like, but is usually about 10 to 50 μm.

(Manufacturing method of multilayer ceramic capacitor 1)
In the multilayer ceramic capacitor 1 of this embodiment, a green chip is produced by a normal printing method or a sheet method using a paste, and fired, and then printed or transferred an external electrode, similarly to a conventional multilayer ceramic capacitor. It is manufactured by baking. Hereinafter, the manufacturing method will be specifically described.

  First, the dielectric material powder contained in the dielectric layer paste is prepared, and this is made into a paint to prepare the dielectric layer paste.

  The dielectric layer paste may be an organic paint obtained by kneading a dielectric material powder and an organic vehicle, or may be a water-based paint.

  As the dielectric raw material powder, the above-mentioned oxides, a mixture thereof, and a composite oxide can be used. In addition, various compounds that become the above-described oxide or composite oxide by firing, such as carbonates and oxalates. , Nitrates, hydroxides, organometallic compounds, and the like may be selected as appropriate and used as a mixture. What is necessary is just to determine content of each compound in a dielectric material powder so that it may become a composition of an 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. Further, the organic solvent 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 used for the water-based vehicle is not particularly limited, and for example, polyvinyl alcohol, cellulose, water-soluble acrylic resin, etc. may be used.

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

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

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

  When the printing method is used, the dielectric layer paste and the internal electrode layer paste are laminated and printed 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.

  The green chip is subjected to binder removal processing and firing processing. The binder removal process and the firing process may be appropriately determined according to the type of the conductive material in the internal electrode layer paste. When firing in a reducing atmosphere, it is preferable to anneal the capacitor element body. Annealing is a process for re-oxidizing the dielectric layer, and this can significantly increase the IR lifetime, thereby improving the reliability.

  The capacitor element body obtained as described above is subjected to end surface polishing, for example, by barrel polishing or sand blasting, and the external electrode paste is printed or transferred and baked to form the external electrode 4. The firing condition of the external electrode paste is preferably, for example, about 10 minutes to 1 hour at 600 to 800 ° C. in a humidified mixed gas of N 2 and H 2. 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 the present invention thus manufactured is mounted on a printed circuit board by soldering or the like and used for various electronic devices.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.
Example 1

First, (Ba _1-x Ca _x ) _m (Ti _1-y Zr _y ) _n O ₃ having an average material particle diameter of 0.20 μm was prepared as a main component material. In addition, as a raw material of the subcomponent, MgCO ₃ (first subcomponent), Y ₂ O ₃ (or other second subcomponent), MnO (or other third subcomponent), SiO ₂ (or other 4th subcomponent), and V ₂ O ₅ (or other fifth subcomponent). The raw material of the main component and the raw material of the subcomponent prepared above were mixed by a ball mill so that the amounts shown in Table 1 and Table 3 were obtained. The obtained mixed powder was calcined at 1000 ° C. to prepare calcined powder having an average particle size of 0.2 μm. Next, the obtained calcined powder was wet pulverized with a ball mill for 15 hours and dried to obtain a dielectric material. In addition, MgCO3 will be contained in a dielectric ceramic composition as MgO after baking. Note that “*” in the table indicates a comparative example.

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

  Separately from the above, Ni particles: 45 parts by mass, terpineol: 52 parts by mass, and ethyl cellulose: 3 parts by mass were kneaded with three rolls and slurried to prepare an internal electrode layer paste.

  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 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 sintered body.

  The binder removal treatment conditions were temperature rising rate: 25 ° C./hour, holding temperature: 250 ° C., temperature holding time: 8 hours, and atmosphere: in the air.

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

  The annealing conditions are: temperature rising rate: 200 ° C./hour, holding temperature: 1000 ° C., temperature holding time: 2 hours, cooling rate: 200 ° C./hour, atmospheric gas: humidified N 2 gas (oxygen partial pressure: 10 −7 MPa) It was.

  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 multilayer ceramic capacitor sample was 2.0 mm × 1.2 mm × 0.5 mm, the thickness of the dielectric layer was 1.6 μm, the thickness of the internal electrode layer was 1.2 μm, and was sandwiched between the internal electrode layers The number of dielectric layers was 10.

  As shown in Table 1 and Table 3, by changing the molar ratio indicating the composition of the main component and the number of moles of subcomponents relative to the main component, for each of the obtained multilayer ceramic capacitor samples, the relative dielectric constant (εs), Insulation resistance (IR), capacitance change rate (ΔC), and high temperature load life (HALT) were measured by the following methods. The results are shown in Table 2 and Table 4.

  The relative dielectric constant εs is measured with a digital LCR meter (YHP 4274A) at a reference temperature of 25 ° C. and a frequency of 1 kHz and an input signal level (measurement voltage) of 0.5 Vrms / μm with respect to the multilayer ceramic capacitor sample. Calculated from the measured capacitance (no unit). It is preferable that the relative dielectric constant is high. In this example, 4000 or more was considered good. The results are shown in Table 2 and Table 4.

  Insulation resistance (IR) was measured for a multilayer ceramic capacitor sample after applying DC 10 V for 60 seconds at 25 ° C. using an insulation resistance meter (R8340A manufactured by Advantest). The product of the capacitance C measured above and the insulation resistance IR was determined and used as the CR product. In this example, a CR product of 2,000Ω · F or more was considered good. The results are shown in Table 2 and Table 4.

  The rate of change in capacitance (ΔC) was 1 kHz at a frequency of 1 kHz and an input signal level (measurement voltage) of 0.2 Vrms at −55 ° C. and 85 ° C. with a digital LCR meter (YHP 4284A). / Μm, 0.05Vrms / μm, the capacitance is measured, the change rate of the capacitance at + 85 ° C with respect to the capacitance at the reference temperature of 25 ° C (unit:%) is calculated, and the input signal level is Whether the capacitance change rate satisfies the range of −15% to + 15% when 0.2 Vrms / μm, and the capacitance change rate is + 15% or more when the input signal level is 0.05 Vrms / μm. It was investigated whether it satisfied. The results are shown in Table 2 and Table 4.

  The high temperature load life (HALT) was evaluated by measuring the life time of the multilayer ceramic capacitor sample at 180 ° C. while maintaining a DC voltage applied in an electric field of 25 V / μm. In this example, the time from the start of application until the insulation resistance drops by an order of magnitude was defined as the lifetime. Further, this high temperature load life was carried out for 10 multilayer ceramic capacitor samples. In this example, 10 hours or longer was used as a standard. The results are shown in Table 2 and Table 4.

  Regarding the presence / absence of the core / shell structure, the cut surface of the multilayer ceramic capacitor sample was observed with a transmission electron microscope, and 10 or more core / shell structures of dielectric particles were observed within a range of 10 × 10 μm. Therefore, it was judged that there was a core / shell structure, and if it was not, it was judged that there was substantially no structure.

Evaluation 1 (Sample Nos. 1 to 5)
As shown in Table 1 and Table 2, in sample numbers 1 to 4 corresponding to the examples having substantially no core / shell structure, compared to sample number 6 corresponding to the comparative example having the core / shell structure, It was confirmed that the dielectric constant was excellent in terms of a high relative dielectric constant. 4 (A1) and 4 (A2) show cross-sectional photographs of the dielectric particles having the core / shell structure of Sample No. 3 and FIGS. 4 (A1) and (A2). Shown in FIG. 4 (B1) and (B2). 4 (A1) and (B1) are transmission electron microscope (TEM) images, and FIGS. 4 (A2) and (B2) are Y element mapping images for (A1) and (B2). is there. The fact that there is substantially no core-shell structure here is as described above.

  FIG. 3 shows the change in relative dielectric constant εs with respect to temperature in the multilayer ceramic capacitor sample according to sample number 3. FIG. 3 shows the temperature dependence of each relative dielectric constant when the applied electric field strength is changed by changing the thickness of the dielectric layer. By reducing the thickness of the dielectric layer and thereby increasing the electric field strength applied to the dielectric layer, the relative dielectric constant is preferably 4000 or more in the operating temperature range (−55 ° C. to 85 ° C.). More preferably, it is confirmed that it can be kept substantially constant at 5000 or more, particularly preferably at 6000 or more. It is also confirmed that X5R characteristics can be secured.

  Moreover, in sample number 5, since there was too much calcium content in a main component, it was confirmed that it is inferior to an Example in the point of an electrostatic capacitance change rate.

Evaluation 2 (Sample Nos. 6 to 11)
As shown in Table 1 and Table 2, by comparing sample numbers 6 to 11, it was confirmed that y in the main component was preferably 0.01 to 0.08. When y is 0.1 or more, the Curie temperature is 85 ° C. or less, and the temperature characteristics of the capacitance are not satisfied.

Evaluation 3 (Sample Nos. 12 to 15)
As shown in Tables 1 and 2, by comparing sample numbers 12 to 15, it was confirmed that m / n in the main component was preferably 0.950 to 1.050. When m / n is less than 0.95, the high temperature load life is shortened, and when m / n exceeds 1.05, the sinterability is lowered and the relative dielectric constant is lowered. Note that “*” in the table indicates a comparative example.

Evaluation 4 (Sample Nos. 16 to 19)
As shown in Table 1 and Table 2, by comparing sample numbers 16 to 19, Mg oxide as the first subcomponent is 0.05 to 0.5 mol with respect to 100 mol of the main component. It was confirmed that it was preferable.

Evaluation 5 (Sample Nos. 20 to 23)
As shown in Tables 3 and 4, yttrium oxide as the second subcomponent is 0.05 to 4 mol with respect to 100 mol of the main component, and the same effect as Sample No. 3 can be obtained. It could be confirmed. When the amount of Y exceeds 4 mol, the sinterability is lowered and the relative dielectric constant is lowered. Note that “*” in the table indicates a comparative example.

Evaluation 6 (Sample Nos. 24-33)
As shown in Tables 3 and 4, even if the yttrium oxide as the second subcomponent is changed to an oxide of La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Yb, the sample number It was confirmed that the same effect as 3 was obtained.

Evaluation 7 (sample numbers 34 to 37)
As shown in Table 3 and Table 4, by comparing sample numbers 34 to 37, the Mn oxide as the third subcomponent is preferably 0.05 to 2 mol with respect to 100 mol of the main component. Was confirmed. When the amount of Mn is less than 0.05 mol%, the insulation resistance is lowered and the high temperature load life is shortened. Further, as shown in Sample No. 38, it was confirmed that the same effect was obtained even when Cr was used instead of Mn.

Evaluation 8 (Sample Nos. 39 to 41)
As shown in Table 3 and Table 4, it was confirmed that the silicon oxide as the fourth subcomponent has the same effect as Sample No. 3 at 0.1 to 5 mol with respect to 100 mol of the main component. did it.

Evaluation 9 (Sample Nos. 42 to 44)
As shown in Table 3 and Table 4, it was confirmed that the same effect as Sample No. 3 was obtained even when the silicon oxide as the fourth subcomponent was changed to the composite oxide shown in Table 3.
Evaluation 10 (Sample Nos. 45-46)

As shown in Table 3 and Table 4, it was confirmed that the vanadium oxide as the fifth subcomponent had the same effect as Sample No. 3 at 0 to 0.2 mol with respect to 100 mol of the main component. did it.
Evaluation 11 (Sample Nos. 47 to 50)

  As shown in Tables 3 and 4, it was confirmed that the same effect as Sample No. 3 was obtained even when the vanadium oxide as the fifth subcomponent was changed to an oxide of Mo, W, Ta, and Nb.

  According to the present invention, a highly reliable monolithic ceramic capacitor can be supplied even if the layer is thinned, so that an electronic component element used in a PC, a small portable device, or the like can be downsized.

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

Claims (7)

In a multilayer ceramic capacitor in which dielectric layers and internal electrode layers are alternately stacked,
When the AC electric field strength applied to the dielectric layer sandwiched between the internal electrode layers is 0.05 Vrms / μm or less, the capacitance change rate ΔC at 85 ° C. with respect to room temperature (25 ° C.) of the multilayer ceramic capacitor is A dielectric ceramic composition in which the capacitance change rate ΔC is in the range of −15% to + 15% when the AC electric field strength is 15 V or more and the AC electric field strength is 0.2 Vrms / μm or more is used. Characteristic multilayer ceramic capacitor.   The multilayer ceramic capacitor according to claim 1, wherein the dielectric layer has a portion where the thickness of the dielectric layer is 1 μm or less and the number of particles in the interlayer thickness direction is 1 to 2. When the BaTiO ₃ perovskite compound is expressed as ABO ₃ , A is at least one selected from Ba, Sr, and Ca, and B is at least selected from Ti, Zr, Hf, and Sn. The multilayer ceramic capacitor according to claim 1, wherein the multilayer ceramic capacitor is one type. The main component of the dielectric layer is a dielectric ceramic composition represented by the general formula: (Ba _1-x Ca _x ) _m (Ti _1-y Zr _y ) _n O ₃
The multilayer ceramic according to claim 1, wherein 0 ≦ x ≦ 0.06, 0.01 ≦ y ≦ 0.08, and 0.950 ≦ m / n ≦ 1.050 in the general formula. Capacitor.     The multilayer ceramic capacitor according to claim 1, wherein the dielectric layer includes 0.05 to 0.5 mol% of Mg as a first subcomponent with respect to the main component in terms of MgO.   The dielectric layer includes a second subcomponent made of a rare earth element, and the second subcomponent is at least one selected from Y, Dy, Ho, Yb, Tb, Gd, Er, Sm, and Eu. The multilayer ceramic capacitor according to claim 1, comprising rare earth element in an amount of 0.05 to 4.0 mol% in terms of each element with respect to the main component.   The multilayer ceramic capacitor according to claim 1, wherein the dielectric layer further contains Mn or Cr as a third subcomponent in an element conversion of 0.05 to 2.0 mol% with respect to the main component.