JP4098206B2 - Dielectric porcelain composition and electronic component - Google Patents

Description

  The present invention relates to a dielectric ceramic composition used as, for example, a dielectric layer of a multilayer ceramic capacitor, and an electronic component using the dielectric ceramic composition as a dielectric layer.

  A multilayer ceramic capacitor, which is an example of an electronic component, includes, for example, ceramic green sheets made of a predetermined dielectric ceramic composition and internal electrode layers of a predetermined pattern alternately stacked, and then integrated into a green chip obtained simultaneously. Manufactured by firing. Since the internal electrode layer of the multilayer ceramic capacitor is integrated with the ceramic dielectric by firing, it is necessary to select a material that does not react with the ceramic dielectric. For this reason, as a material constituting the internal electrode layer, conventionally, an expensive noble metal such as platinum or palladium has been inevitably used.

  On the other hand, in order to use an inexpensive base metal (for example, nickel or copper) as a material for the internal electrode, it does not become a semiconductor even if it is fired at a low temperature in a neutral or reducing atmosphere, that is, it has reduced resistance. It is necessary to develop a dielectric ceramic composition that is excellent and has a sufficient dielectric constant and excellent dielectric properties (for example, a small rate of change in capacitance temperature) after firing.

  Various proposals have been made as dielectric ceramic compositions in which a base metal such as nickel or copper can be used as the material of the internal electrode (see, for example, Patent Document 1).

Patent Document 1 includes 86.32 to 97.64 mol of BaTiO ₃ , 0.01 to 10.00 mol of Y ₂ O ₃ , 0.01 to 10.00 mol of MgO, 0.001 to 0.200. A reduction-resistant dielectric ceramic composition characterized in that it consists of a molar amount of V ₂ O ₅ is disclosed. In this document, even if the nickel used for the internal electrode is baked in a neutral or reducing atmosphere so as not to oxidize, the dielectric ceramic composition is reduced and the lifetime is shortened by reducing the dielectric ceramic composition. It is described that it is possible to obtain a laminated ceramic capacitor with a small capacitance change in temperature.

Incidentally, according to this document, the total amount of _{MnO · Cr 2 O 3 · Co} 2 O 3 is less than 0.01 mol%, the dielectric ceramic composition ends up semiconductive, good results to obtain the total amount of _{MnO · Cr 2 O 3 · Co} 2 O 3 are described to be necessary in the range of 0.01 mol% to 10 mol%, which is specifically disclosed in this document Capacitor samples, particularly those disclosed in the examples, all contain MnO and / or Cr ₂ O ₃ .

  On the other hand, in recent years, there is a high demand for downsizing of electronic components due to higher density of electronic circuits, and downsizing and increasing capacity of multilayer ceramic capacitors are rapidly progressing. As a result, dielectric layers per layer in multilayer ceramic capacitors have become thinner and dielectric layers have increased in number due to an increase in the number of layers. Dielectrics that can maintain the reliability of capacitors even when they are made thinner and multilayered. There is a need for a body porcelain composition.

  In particular, when the dielectric layer is made thin, for example, 5 μm or less, in order to reduce the size and increase the capacity, the internal electrode layer is also made thin, for example, electrode breakage due to electrode oxidation or the like is likely to occur. .

  However, when MnO is added to the dielectric ceramic composition as in Patent Document 1, segregation of MnO occurs in the vicinity of the nickel internal electrode during firing, the nickel electrode is oxidized, and electrode breakage occurs. For this reason, it may lead to failure such as loss of conduction or a decrease in reliability, and this problem becomes remarkable particularly when the dielectric layer is thinned and the multilayer ceramic capacitor is downsized.

Further, Cr ₂ O ₃ is a compound containing chromium, and it is desired to search for an alternative or not use it from the viewpoint of environmental problems.

As described above, the samples disclosed in the examples of Patent Document 1 all contain MnO and / or Cr ₂ O ₃ , and the dielectric ceramic composition does not contain either MnO or Cr ₂ O ₃ . No specific composition range is disclosed. Therefore, when a dielectric ceramic composition that does not contain MnO and Cr ₂ O ₃ is used as a dielectric layer, any composition can be used to obtain a dielectric ceramic composition having high reliability even if it is thinned. It is unclear whether it can be done.

  Patent Document 2 discloses that barium titanate is a main component and R is a subcomponent (where R is at least one of Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb). ), A dielectric ceramic composition which is a composite oxide comprising Ca, Mg and Si elements. In addition, this document describes that the dielectric ceramic composition can further contain V as a subcomponent.

  According to this document, by using the dielectric ceramic composition as a dielectric layer, the temperature characteristics of the capacitance satisfy the B characteristic and the X7R characteristic, and are excellent in reliability even if the layer is thinned. It is described that a capacitor can be obtained.

  On the other hand, when the dielectric layer is made thinner and multilayered for the purpose of downsizing and increasing the capacity of the multilayer ceramic capacitor, the electric field strength (V / μm) applied to the dielectric layer when a DC voltage is applied. Becomes relatively high. Therefore, in order to reduce the size and increase the capacity of the capacitor, not only the above-described performance but also reliability when applying a DC voltage with high electric field strength is required.

However, the capacitor sample specifically disclosed in the above-mentioned Patent Document 2, particularly the sample disclosed in the Examples, discloses a sample actually added with YO _3/2 and a sample added with V as a subcomponent. In addition, nothing is described about the rate of change in capacity temperature when a DC voltage having a high electric field strength, which is important when the layer is thinned, is applied.

Japanese Patent No. 2765513 JP 2001-39765 A

  An object of the present invention is to use a dielectric ceramic composition with high reliability even when the dielectric layer of a multilayer ceramic capacitor is used as a dielectric layer of a multilayer ceramic capacitor and is made thin, for example, 5 μm or less. The object is to provide a dielectric ceramic composition that is excellent in capacity temperature change rate and high-temperature load life characteristics under a high-field strength DC voltage application condition at a high temperature. Another object of the present invention is to provide an electronic component such as a multilayer ceramic capacitor manufactured using such a dielectric ceramic composition and having improved reliability. In particular, an object of the present invention is to provide an electronic component such as a multilayer ceramic capacitor capable of being thinned and miniaturized.

The inventors of the present invention use a dielectric ceramic composition used as a dielectric layer of an electronic component such as a multilayer ceramic capacitor as a dielectric layer of the multilayer ceramic capacitor, and the dielectric layer of the multilayer ceramic capacitor is a thin layer. As a result of diligent investigations on a dielectric ceramic composition excellent in capacity temperature change rate and high temperature load life characteristics under a high-field strength DC voltage application condition at high temperature, the main component BaTiO ₃ and subcomponents A dielectric ceramic composition containing MgO, Y ₂ O ₃ , V ₂ O ₅ , and Ba _α Ca _(1-α) SiO ₃ (where 0 ≦ α ≦ 1). It is found that the object of the present invention can be achieved by limiting and not substantially containing MnO and Cr ₂ O ₃ in the dielectric ceramic composition, and the present invention has been completed. It came to let you.

That is, the dielectric ceramic composition according to the present invention is
BaTiO _{3 as the} main component,
A dielectric ceramic composition containing MgO, Y ₂ O ₃ , V ₂ O ₅ , and Ba _α Ca _(1-α) SiO ₃ (where 0 ≦ α ≦ 1) as subcomponents,
The ratio of each subcomponent to 100 mol of BaTiO _{3 as the} main component is
MgO: 0.1 to 3 mol Y ₂ O _3: 0.5~3 moles V ₂ O _5: 0.01~0.2 moles _{Ba α Ca (1-α)} SiO 3: 0.5 to 10 moles And MnO and Cr ₂ O ₃ are not substantially contained.

In the dielectric ceramic composition according to the present invention, preferably, the content of MnO in the dielectric ceramic composition is 0.01 mol or less with respect to 100 mol of BaTiO _{3 as the} main component, and Preferably it is 0.005 mol or less.

In the dielectric ceramic composition according to the present invention, preferably, the content of Cr ₂ O _{3 in} the dielectric ceramic composition is 0.01 mol or less with respect to 100 mol of BaTiO _{3 as the} main component. More preferably 0.005 mol or less.

  The electronic component according to the present invention has a dielectric layer made of any one of the above dielectric ceramic compositions. Although it does not specifically limit as an electronic component, 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 are illustrated.

  A multilayer ceramic capacitor according to the present invention has a capacitor element body in which dielectric layers composed of the dielectric ceramic composition described above and internal electrode layers are alternately stacked.

In the multilayer ceramic capacitor according to the present invention, preferably, the capacitance temperature when a DC voltage is applied at a temperature of 85 ° C. and an electric field strength of 0.8 V / μm, based on the electrostatic capacity at a temperature of 20 ° C. and an applied voltage of 0 V. The rate of change (ΔC / C ₂₀ ) is within ± 10%.

  In the multilayer ceramic capacitor according to the present invention, preferably, the dielectric layer has a thickness of 5 μm or less.

  In the multilayer ceramic capacitor according to the present invention, preferably, the average particle diameter of the dielectric particles constituting the dielectric layer is less than 0.8 μm.

  In the multilayer ceramic capacitor according to the present invention, preferably, the average value of the particle diameters arranged in the stacking direction of the dielectric layers is 1/3 or less of the interlayer distance of the internal electrode layers.

  In the multilayer ceramic capacitor according to the present invention, preferably, in a high temperature load life measurement measured by maintaining a test temperature of 200 ° C. and a DC voltage application state of 30 V / μm, from the start of application of the DC voltage, the DC In the voltage application state, the time until the current value of the detected current becomes 2 mA or more is 35 hours or more.

According to the present invention, a dielectric ceramic composition containing BaTiO _{3 as} a main component, MgO as subcomponents, Y ₂ O ₃ , V ₂ O ₅ , and Ba _α Ca _(1-α) SiO ₃ . In the above, the composition range of the subcomponent is limited, and MnO and Cr ₂ O ₃ are not substantially contained, so that the dielectric layer of the multilayer ceramic capacitor is thinned. However, it is possible to provide a dielectric ceramic composition that is excellent in capacity temperature change rate and high temperature load life characteristics in a DC voltage application state with high electric field strength at high temperature.

  In addition, according to the present invention, it is possible to provide an electronic component such as a multilayer ceramic capacitor excellent in capacity temperature change rate and high temperature load life characteristics in a DC voltage application state at a high temperature and high electric field strength even when the layer is thinned. Can do.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
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 relationship between the electric field strengths and specific resistances ρ of the samples of Examples and Comparative Examples of the present invention,
FIG. 3 is a graph showing the relationship between each electric field strength and the logarithm log ρ of the specific resistance ρ of the samples of Examples and Comparative Examples of the present invention.

  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 element body 10. The shape of the capacitor element body 10 is not particularly limited, but is usually a rectangular parallelepiped shape. Also, there is no particular limitation on the dimensions, and it may be an appropriate dimension according to the application. Usually, (0.4 to 5.6 mm) × (0.2 to 5.0 mm) × (0.2 ˜1.9 mm).

  The internal electrode layers 3 are laminated so that the respective 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 connected to the exposed end surfaces of the alternately arranged internal electrode layers 3 to constitute a capacitor circuit.

The dielectric layer 2 contains the dielectric ceramic composition of the present invention.
The dielectric ceramic composition of the present invention includes BaTiO _{3 as} a main component,
A dielectric ceramic composition containing MgO, Y ₂ O ₃ , V ₂ O ₅ , and Ba _α Ca _(1-α) SiO ₃ (where 0 ≦ α ≦ 1) as subcomponents,
It is substantially free of MnO and Cr ₂ O ₃ .

BaTiO _{3 as the} main component can be produced using a known production method such as a solid phase method, an oxalate method, a hydrothermal synthesis method, an alkoxide method, a sol-gel method, or the like.

The content of MgO, relative to BaTiO ₃ 100 moles are 0.1 to 3 moles, preferably 0.5 to 2.5 moles, more preferably 1.0 to 2.0 moles.

MgO has an effect of improving the reduction resistance and an effect of improving the high temperature load life characteristic. If the content of MgO is too small, such an effect tends to be not obtained. There is a tendency for the cohesiveness to deteriorate and the relative dielectric constant (ε _r ) to decrease.

The content of Y ₂ O _3, relative to BaTiO ₃ 100 moles are 0.5 to 3 moles, preferably 1.0 to 3 mol.

Y ₂ O ₃ has the effect of improving the high temperature load life characteristics. If the content of Y ₂ O ₃ is too small, such an effect tends to be lost, and if it is too much, the sinterability deteriorates. Tend to.

The content of V ₂ O _5, relative to BaTiO ₃ 100 moles, 0.01 to 0.2 mol, preferably 0.01 to 0.12 mol, more preferably, 0.06 to 0.12 Is a mole.

V ₂ O ₅ has the effect of flattening the capacity-temperature characteristics above the Curie temperature and the effect of improving the IR lifetime. If the content of V ₂ O ₅ is too small, the added effect cannot be obtained. If the amount is too much, IR tends to be remarkably lowered.

The content of _{Ba α Ca (1-α)} SiO 3 , relative to BaTiO ₃ 100 moles, and 0.5 to 10 mol, preferably 0.5 to 3.0 moles, more preferably 0.5 -2.0 mol.

Ba _α Ca _(1-α) SiO ₃ has the effect of improving the sinterability and reducing the occurrence of the initial IR failure rate. If the content of Ba _α Ca _(1-α) SiO ₃ is too small, Sinterability tends to deteriorate, and if it is too much, the dielectric constant tends to decrease.

Further, since Ba _α Ca _(1-α) SiO ₃ , which is a complex oxide, has a low melting point and good reactivity with respect to the main component, it is more preferable than adding it as BaO and CaO, which are single oxides, respectively. Then, it is preferable to add BaO and / or CaO as the composite oxide.

  The symbol α indicating the composition molar ratio of Ba and Ca is arbitrary (0 ≦ α ≦ 1) and may contain only one, but preferably 0.3 ≦ α ≦ 0.7. It is.

The feature of the dielectric ceramic composition of the present invention is a dielectric ceramic composition containing BaTiO _{3 as} a main component and each of the above-mentioned subcomponents, and substantially free of MnO and Cr ₂ O _3. Is a point.

In the dielectric ceramic composition of the present embodiment, the MnO content is not particularly problematic as long as it is substantially free, but is preferably 0.01 mol or less with respect to 100 mol of BaTiO ₃ . More preferably, it is 0.005 mol or less, More preferably, it is 0.001 mol or less.

  MnO segregates in the vicinity of the nickel internal electrode during firing and oxidizes the nickel electrode. Therefore, if there is too much MnO in the dielectric ceramic composition, there is a tendency that temperature characteristics in a DC voltage applied state deteriorate, failure such as failure of conduction, or a decrease in reliability.

Further, the content of Cr ₂ O ₃ is not particularly limited as long as it is substantially not contained, but is preferably 0.01 mol or less, more preferably 0.8 mol, relative to 100 mol of BaTiO ₃ . 005 mol or less, more preferably 0.001 mol or less.

Since Cr ₂ O ₃ is an oxide of chromium that causes environmental problems, it is desirable that Cr ₂ O ₃ is not substantially contained from the viewpoint of protecting the global environment. If the content of Cr ₂ O ₃ is too large, the temperature characteristic deteriorates in the DC voltage applied state, at high temperatures, tends to increase the electric field strength dependency of the insulation resistance.

  The thickness of the dielectric layer 2 is not particularly limited, but is preferably 10 μm or less per layer, more preferably 5 μm or less, more preferably 3 μm or less. Although the minimum of thickness is not specifically limited, For example, it is about 0.5 micrometer.

  The average particle diameter of the dielectric particles contained in the dielectric layer 2 is not particularly limited, but is preferably less than 0.8 μm, and more preferably less than 0.4 μm. Although the minimum of an average particle diameter is not specifically limited, For example, it is about 0.15 micrometer. By reducing the average particle size, the high temperature load life can be improved.

  In the present embodiment, preferably, the average value of the particle diameters arranged in the stacking direction of the dielectric layer 2 is 1/3 or less of the interlayer distance of the internal electrode layer, and more preferably 1/6 or less. is there.

  As in this embodiment, when the particle diameters arranged in the laminating direction of the dielectric layer 2 are set to 1/3 or less of the interlayer distance of the internal electrode layers, they are arranged in the laminating direction per dielectric layer The average number of dielectric particles can be 3 or more. By doing so, it is possible to reduce the IR defect rate and improve the IR life characteristics.

  The conductive material contained in the internal electrode layer 3 is not particularly limited, but a 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 thickness of the internal electrode layer 3 may be appropriately determined according to the application and the like, but is usually 0.1 to 3 μm, particularly preferably about 0.2 to 2.0 μm.

  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. The thickness of the external electrode 4 may be determined as appropriate according to the application and the like, but is usually preferably about 10 to 50 μm.

  In the multilayer ceramic capacitor using the dielectric ceramic composition of the present invention, as in the conventional multilayer ceramic capacitor, a green chip is produced by a normal printing method or sheet method using a paste, and this is fired, and then externally It is manufactured by printing or transferring an electrode and firing. Hereinafter, the manufacturing method will be specifically described.

  First, the dielectric ceramic composition 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 ceramic composition powder and an organic vehicle, or may be a water-based paint.

  As the dielectric ceramic composition powder, the above-described oxides, mixtures thereof, and composite oxides can be used. In addition, various compounds that become the above-described oxides and composite oxides by firing, such as carbonates and An acid salt, a nitrate, a hydroxide, an organometallic compound, or the like can be appropriately selected and mixed for use. What is necessary is just to determine content of each compound in a dielectric ceramic composition powder so that it may become a composition of the above-mentioned dielectric ceramic composition after baking. The particle size of the dielectric ceramic composition powder is usually about 0.1 to 1 [mu] m in average before the coating.

  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 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, depending on 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, or the like may be used.

  The internal electrode layer paste is prepared 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 using the printing method, 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 off 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. The binder removal treatment may be appropriately determined according to the type of the conductive material in the internal electrode layer paste. However, when a base metal such as Ni or Ni alloy is used as the conductive material, the oxygen partial pressure in the binder removal atmosphere is 10 It is preferable to be ⁻⁴⁵ to 10 ⁵ Pa. When the oxygen partial pressure is less than the above range, the binder removal effect is lowered. If the oxygen partial pressure exceeds the above range, the internal electrode layer tends to oxidize.

As other binder removal conditions, the temperature rising rate is preferably 5 to 300 ° C./hour, more preferably 10 to 100 ° C./hour, and the holding temperature is preferably 180 to 400 ° C., more preferably 200 to 350. The temperature holding time is preferably 0.5 to 24 hours, more preferably 2 to 20 hours. The firing atmosphere is preferably air or a reducing atmosphere, and as an atmosphere gas in the reducing atmosphere, for example, a mixed gas of N ₂ and H ₂ is preferably used after being humidified.

The atmosphere at the time of green chip firing may be appropriately determined according to the type of 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 ⁻⁹ to 10 ⁻⁴ Pa. 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.

  Moreover, the holding temperature at the time of baking becomes like this. Preferably it is 1100-1400 degreeC, More preferably, it is 1200-1350 degreeC. If the holding temperature is lower than the above range, the densification becomes insufficient. If the holding temperature is higher than the above range, the electrode temperature is interrupted due to abnormal sintering of the internal electrode layer, the capacity temperature characteristic deteriorates due to diffusion of the internal electrode layer constituent material, and the dielectric Reduction of the body porcelain composition is likely to occur.

As other firing conditions, the rate of temperature rise is preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour, and the temperature holding time is preferably 0.5 to 8 hours, more preferably 1 to 3 hours. The time and cooling rate are preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° 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 is preferably used by humidification.

  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 oxygen partial pressure in the annealing atmosphere is preferably 10 ⁻³ Pa or more, particularly preferably 10 ^{−2 to} 10 Pa. When the oxygen partial pressure is less than the above range, it is difficult to reoxidize the dielectric layer, and when it exceeds the above range, the internal electrode layer tends to be oxidized.

  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 IR is low and the IR life tends to be short. On the other hand, if the holding temperature exceeds the above range, not only the internal electrode layer is oxidized and the capacity is lowered, but the internal electrode layer reacts with the dielectric substrate, the capacity temperature characteristic is deteriorated, the IR is lowered, the IR Life 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, more preferably 2 to 10 hours, and the cooling rate is preferably 50 to 500 ° C./hour, more preferably 100 to 300 ° C./hour. . Further, as the annealing atmosphere gas, for example, humidified N ₂ gas or the like 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 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 conditions of the external electrode paste are 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.

  Note that the multilayer ceramic capacitor of this embodiment is excellent in temperature characteristics and high temperature load life characteristics in a DC voltage application state with high electric field strength even when the dielectric layer is thinned, for example, 5 μm or less.

For example, when the electrostatic capacity at a temperature of 20 ° C. and an applied voltage of 0 V is used as a reference, the capacity temperature change rate (ΔC / C ₂₀ ) in the applied state of a DC voltage at a temperature of 85 ° C. and an electric field strength of 0.8 V / μm is Preferably, it is within ± 10%.

  The high temperature load life characteristic is detected from the start of application of the DC voltage to the application state of the DC voltage under the condition that the test temperature is maintained at a test temperature of 200 ° C. and a DC voltage of 30 V / μm, for example. The time until the current value of the current becomes 2 mA or more is preferably 35 hours or more, and more preferably 50 hours or more.

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

  For example, in the 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 is composed of a dielectric ceramic composition having the above composition. Any material having a dielectric layer can be used.

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

Example 1
BaTiO ₃ and TiO ₂ were prepared as starting materials in a Ba / Ti molar ratio of 0.990 to 1.010, and BaTiO ₃ was prepared by chemical reaction by a solid phase method. The average particle size of the obtained BaTiO ₃ was 0.4 μm.

BaTiO ₃ prepared above as a main component, MgO, Y ₂ O ₃ , V ₂ O ₅ , Ba _α Ca _(1-α) SiO ₃ (where 0 ≦ α ≦ 1) as subcomponents The main component and each subcomponent were weighed and prepared so as to have the compositions shown in Tables 1 to 5. Further, MnO was added to Samples 22 and 23 shown in Table 5, and Cr ₂ O ₃ was further added to Samples 24 and 25 as subcomponents. As Ba _α Ca _(1-α) SiO ₃ , α = 0.58, that is, Ba _0.58 Ca _0.42 SiO ₃ was used.

  Next, the weighed and prepared main component and each subcomponent were wet mixed by a ball mill for 16 hours and dried to obtain a dielectric material.

  100 parts by weight of the obtained dielectric material, 6 parts by weight of acrylic resin, 6 parts by weight of toluene, 3.5 parts by weight of methyl ethyl ketone, 6 parts by weight of mineral spirit, and 4 parts by weight of acetone are mixed with a ball mill, A dielectric layer paste was obtained by pasting.

  100 parts by weight of Ni particles having an average particle size of 0.2 to 0.8 μm, 40 parts by weight of an organic vehicle (8 parts by weight of ethyl cellulose dissolved in 92 parts by weight of butyl carbitol), and 10 parts by weight of butyl carbitol It knead | mixed with 3 rolls and was made into the paste and obtained the paste for internal electrode layers.

  Using the obtained dielectric layer paste, a sheet was formed by a doctor blade method on a PET film and dried to form a green sheet. At this time, the thickness of the green sheet was 3.5 μm. After the internal electrode paste was printed thereon, the sheet was peeled from the PET film. Next, these green sheets and protective green sheets (not printed with internal electrode layer paste) were laminated and pressure-bonded to obtain green chips.

  Next, the green chip was cut into a predetermined size and subjected to binder removal processing, firing and annealing under the following conditions to obtain a multilayer ceramic fired body. The binder removal treatment was performed by heating at 250 ° C. in air.

Firing was performed for 2 hours at each firing temperature shown in Tables 1 to 5 in a reducing atmosphere composed of H ₂ —N ₂ —H ₂ O with the oxygen partial pressure controlled to 10 ⁻⁵ to 10 ⁻⁸ Pa. .

The annealing was performed by heating at 900 to 1100 ° C. for 2 hours in a humidified N ₂ gas atmosphere in order to compensate for the oxygen deficient in the firing.
Note that a wetter with a water temperature of 35 ° C. was used for humidifying the atmospheric gas during firing and reoxidation treatment.

  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 was 3.2 mm × 1.6 mm × 0.6 mm, and the number of dielectric layers sandwiched between internal electrode layers was 100, and the thickness of the dielectric layers per layer (interlayer thickness) ) Was 2.5 μm, and the thickness of the internal electrode layer was 1.5 μm. Further, when the average particle size in the dielectric layer of each sample was examined, it was 0.4 μm.

Furthermore, MnO for samples 1 to 21 without the addition of MnO and _Cr 2 _{O 3,} by high-frequency induction plasma emission (ICP) composition analysis method, a result of measuring the content of MnO and _Cr 2 _{O 3,} all samples Is less than 0.0005% and Cr ₂ O ₃ is less than 0.003%. That is, the content of MnO is less than 0.00167 mol and the content of Cr ₂ O ₃ is 0 with respect to 100 mol of BaTiO _3. It was confirmed that the amount was less than 0.005 mol.
The following characteristics were evaluated for each sample.

Dielectric constant (ε _r )
The capacitance of the capacitor sample was measured at a reference temperature of 25 ° C. with a digital LCR meter (YHP 4274A) under the conditions of a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms. Then, the relative dielectric constant (no unit) was calculated from the obtained capacitance. The results are shown in Tables 1-5.

Capacity temperature change rate (ΔC / C ₂₀ )
At a temperature of −25 ° C. and 85 ° C., a DC voltage with an electric field strength of 0.8 V / μm was applied to the capacitor sample, and the capacitance in the applied state of the DC voltage was measured. The rate of change in capacitance temperature (ΔC / C ₂₀ ) at each temperature was calculated based on the capacitance.

High temperature load life (Acceleration life of insulation resistance / HALT)
The capacitor sample was held at 200 ° C. with a DC voltage of 30 V / μm, and the high temperature load life was measured. This high temperature load life is particularly important when the dielectric layer is thinned. In this embodiment, in a DC voltage application state, the time from the start of application until the current value of the detected current becomes 2 mA or more is defined as the life, and this is performed for 10 capacitor samples, and the average life time is calculated. Calculated. The results are shown in Tables 1-5.

  Table 1 shows the firing temperature, the relative dielectric constant, the rate of change in capacity temperature at each temperature, and the high temperature load life when the amount of the minor component MgO is changed.

From Table 1, Samples 2 to 5 of Examples in which MgO is within the scope of the present invention have a capacity temperature change rate (ΔC / C ₂₀ ) when a DC voltage is applied at a temperature of 85 ° C. and an electric field strength of 0.8 V / μm. However, all were within ± 10%, and good results were obtained. The high temperature load life was 35 hours or more in all cases, and Samples 3 and 4 showed particularly good results of 60 hours or more. Moreover, when the content of MgO was increased, the specific permittivity tended to decrease, but both values were high.

On the other hand, the sample 1 of the comparative example in which the addition amount of MgO is 0.05 mol with respect to 100 mol of BaTiO ₃ has a short high-temperature load life of 15 hours, and the sample 6 of the comparative example in which 3.42 mol is used is The value of the capacity temperature change rate (ΔC / C ₂₀ ) at a temperature of 85 ° C. was −10.7%, which is less than −10%.

  From this result, the amount of the minor component MgO is desirably 0.1 to 3 mol, preferably 0.5 to 2.5 mol, and more preferably 1.0 to 2.0 mol. I was able to confirm.

Table 2 shows the firing temperature, the relative dielectric constant, the rate of change in capacity temperature at each temperature, and the high temperature load life when the amount of Y ₂ O ₃ as a subcomponent is changed.

From Table 2, the samples 4 and 8 to 10 of Examples in which Y ₂ O ₃ is within the scope of the present invention, the capacity temperature change rate in the applied state of DC voltage with a temperature of 85 ° C. and an electric field strength of 0.8 V / μm ( ΔC / C ₂₀ ) was within ± 10%, and good results were obtained. The high temperature load life was 35 hours or more, and Samples 4, 9, and 10 were particularly good results of 60 hours or more. Moreover, when the content of Y ₂ O ₃ was increased, the specific permittivity also tended to improve, and both values were high.

On the other hand, the sample 7 of the comparative example in which the amount of Y ₂ O ₃ added was 0.20 moles with respect to 100 moles of BaTiO ₃ had a high temperature load life of 19 hours and was 3.31 moles. Since sample 11 had poor sinterability and the firing temperature had to be as high as 1330 ° C., many defective products were generated as a result.

From this result, it was confirmed that the amount of Y ₂ O _{3 as} a subcomponent was desirably 0.5 to 3 mol, and preferably 1.0 to 3 mol.

Table 3 shows the firing temperature, the relative dielectric constant, the capacity temperature change rate at each temperature, and the high temperature load life when the amount of the subcomponent V ₂ O ₅ is changed.

From Table 3, Samples 4 and 13 to 15 of Examples in which V ₂ O ₅ is within the scope of the present invention have a capacity temperature change rate (DC temperature application state at a temperature of 85 ° C. and an electric field strength of 0.8 V / μm ( ΔC / C ₂₀ ) was within ± 10%, and good results were obtained. In addition, as for the high temperature load life, all achieved 35 hours or more, and good results were obtained. Moreover, when the content of V ₂ O ₅ was increased, the relative dielectric constant tended to decrease, but both values were high.

On the other hand, the sample 12 of the comparative example in which V ₂ O ₅ was not added and the sample 16 of the comparative example in which the addition amount of V ₂ O ₅ was 0.24 mol with respect to 100 mol of BaTiO ₃ had a high temperature load life. The results were shortened to 31 hours and 12 hours, respectively.

From this result, it is desirable that the amount of V ₂ O ₅ as a subcomponent is 0.01 to 0.2 mol, preferably 0.01 to 0.12 mol, more preferably 0.06 to 0. It was confirmed to be 12 mol.

Table 4 shows the firing temperature, the relative dielectric constant, the capacity temperature change rate at each temperature, and the high temperature load life when the amount of the Ba _α Ca _(1-α) SiO _{3 as} a subcomponent is changed. In this embodiment, α = 0.58.

From Table 4, Samples 4 and 18 to 21 of Examples in which Ba _α Ca _(1-α) SiO ₃ is within the scope of the present invention are applied with a DC voltage at a temperature of 85 ° C. and an electric field strength of 0.8 V / μm. The rate of change in capacity temperature (ΔC / C ₂₀ ) was within ± 10%, which was a favorable result. In addition, the high temperature load life was 35 hours or more in all cases, and Samples 4, 18, and 19 had particularly good results of 60 hours or more. Moreover, when the content of Ba _α Ca _(1-α) SiO ₃ was increased, the relative dielectric constant tended to decrease, but both values were high.

On the other hand, the sample 17 of the comparative example in which the addition amount of Ba _α Ca _(1-α) SiO ₃ is 0.12 mol with respect to 100 mol of BaTiO ₃ has a short high-temperature load life of 27 hours, Since the calcination was poor and the firing temperature had to be increased to 1320 ° C., many defective products were generated. Further, the sample 22 of the comparative example the amount of _{Ba α Ca (1-α)} SiO 3 and 12.03 mol, -25 ° C., at both temperatures of + 80 ° C., the capacity temperature change rate (ΔC _{/ C 20)} The results were less than -13.2%, -11.1% and -10%, respectively, and the high temperature load life was shortened to 20 hours.

From this result, it is desirable that the amount of Ba _α Ca _(1-α) SiO _{3 as} a subcomponent is 0.5 to 10 mol, preferably 0.5 to 3.0 mol, more preferably 0. It was confirmed that it was 0.5 to 2.0 mol.

Table 5 shows the firing temperature, relative dielectric constant, capacity temperature change rate at each temperature, and high temperature load life when MnO and Cr ₂ O ₃ are added as subcomponents.

From Table 5, the samples 23 to 26 of the comparative example to which MnO and Cr ₂ O ₃ were added had a capacity temperature change rate (ΔC / C ₂₀ ) in the applied state of DC voltage at a temperature of 85 ° C. and an electric field strength of 0.8 V / μm. However, in both cases, the result exceeded 10%. It was also confirmed that when the amount of MnO and Cr ₂ O ₃ added was increased, the rate of change in capacity temperature was likely to deteriorate.

From this result, it is desirable that MnO and Cr ₂ O ₃ are not substantially contained. Preferably, the amount of MnO and / or Cr ₂ O ₃ added is 0.01 mol with respect to 100 mol of BaTiO _3. I was able to confirm.

Example 2
Capacitor sample 4 to which MnO was not added and capacitor sample 23 in which 0.01 mol of MnO was added to 100 mol of BaTiO ₃ ,
The electrode breakage rate of the nickel electrode at the center and the end of the capacitor chip was measured by EPMA (Electron Probe MicroAnalysis).

  As a measuring method, first, a capacitor sample is cut by a surface as shown in FIG. 1, the cut surface is mirror-polished to be a surface, and a 60 × 60 μm square area is scanned at intervals of 0.2 μm. Each element of Ni, Mn, and O was mapped. Next, in the part considered to be the occupied area of the Ni electrode in the visual field mapped by EPMA, the part where Mn and O were detected and Ni was not detected was defined as the electrode interruption. And the ratio of the total area of this electrode discontinuity was calculated | required with respect to the total area of the part considered to be the occupation part of Ni electrode, and this was made into the discontinuation rate of a nickel electrode. In addition, the measurement was performed at two places for each of 15 electrode layers at the center and at the end.

As a result of the measurement, the electrode interruption rate was 14% at the center and 19% at the end in the sample 23 , and 0% and 0% at the center in the sample 4. From this result, it was confirmed that in the multilayer ceramic capacitor using the dielectric ceramic composition substantially not containing MnO as the dielectric layer, the electrode breakage rate of the nickel electrode can be kept low.

Example 3
For the capacitor sample 4 to which Cr ₂ O ₃ was not added and the capacitor sample 25 to which 0.01 mol of Cr ₂ O ₃ was added to 100 mol of BaTiO ₃ , the specific resistance ρ ( The unit was Ωcm). FIG. 2 shows the relationship between the electric field strengths of the samples 4 and 25 and the specific resistance ρ, and FIG. 3 shows the change rate of the logarithmic log ρ of each electric field strength and the specific resistance ρ based on the electric field strength of 3.5 V / μm. Showed the relationship.

From FIG. 2, it can be seen that the value of the specific resistance ρ decreases as the electric field strength increases in both the samples 4 and 25 . On the other hand, from FIG. 3, sample 25 which Cr ₂ O ₃ content, as compared to sample 4 no Cr ₂ O ₃ content substantially, the resistivity of the rate of change when increasing the electric field intensity, that greater It was confirmed. From this result, it was confirmed that by containing substantially no Cr ₂ O ₃ , the electric field strength dependence of the specific resistance at a high temperature, for example, 150 ° C. can be reduced, and the reliability of the capacitor can be improved.

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 relationship between each electric field strength and specific resistance ρ of the samples of the examples of the present invention and comparative examples. FIG. 3 is a graph showing the relationship between each electric field strength and the logarithm log ρ of the specific resistance ρ of the samples of Examples and Comparative Examples of the present invention.

Explanation of symbols

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

Claims (8)

BaTiO _{3 as the} main component,
A dielectric ceramic composition containing MgO, Y ₂ O ₃ , V ₂ O ₅ , and Ba _α Ca _(1-α) SiO ₃ (where 0 ≦ α ≦ 1) as subcomponents,
The ratio of each subcomponent to 100 mol of BaTiO _{3 as the} main component is
MgO: 0.1 to 3 mol Y ₂ O _3: 0.5~3 moles V ₂ O _5: 0.01~0.2 moles _{Ba α Ca (1-α)} SiO 3: 0.5 to 10 moles Yes,
The content of MnO is 0.01 mol or less with respect to 100 mol of BaTiO _{3 as the} main component ,
The content of cr ₂ O ₃ is, with respect to BaTiO ₃ 100 moles of said main component, the dielectric ceramic composition is characterized in that 0.01 mol. The electronic component which has a dielectric material layer comprised with the dielectric material ceramic composition of Claim 1 . A multilayer ceramic capacitor having a capacitor element body in which dielectric layers composed of the dielectric ceramic composition according to claim 1 and internal electrode layers are alternately laminated. When the electrostatic capacity at a temperature of 20 ° C. and an applied voltage of 0 V is used as a reference, the rate of change in capacity temperature (ΔC / C ₂₀ ) is ± 10% when a DC voltage is applied at a temperature of 85 ° C. and an electric field strength of 0.8 V / μm. The multilayer ceramic capacitor according to claim 3 , wherein 5. The multilayer ceramic capacitor according to claim 3 , wherein the dielectric layer has a thickness of 5 μm or less. The multilayer ceramic capacitor according to claim 3 , wherein an average particle diameter of dielectric particles constituting the dielectric layer is less than 0.8 μm. The multilayer ceramic capacitor according to claim 3 , wherein an average value of particle diameters arranged in the stacking direction of the dielectric layers is 1/3 or less of an interlayer distance of the internal electrode layers. In a high temperature load life measurement measured by maintaining a test voltage at 200 ° C. and a DC voltage application state of 30 V / μm, the current detected from the start of DC voltage application to the DC voltage application state The multilayer ceramic capacitor according to claim 3 , wherein the time until the value becomes 2 mA or more is 35 hours or more.

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