JP2004319569A - Laminated ceramic capacitor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated ceramic capacitor that is used for various types of electronic equipment and is much more improved in electrical characteristics than the conventional one, and to provide a method of manufacturing the capacitor. <P>SOLUTION: The method of manufacturing the laminated ceramic capacitor includes a step of compounding a dielectric composition, a step of slurrifying the ceramic composition, and a step of molding the slurry into green sheets. The method also includes a step of laminating the green sheets and a step of baking the laminate. By this method, a highly reliable laminated ceramic capacitor having both a high dielectric constant and a low dielectric loss can be manufactured by using BaTiO<SB>3</SB>coated with fine SiO<SB>2</SB>particles as the main component of the dielectric composition. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４０】
（表１）および図１の結果から明らかなように、本発明による実施例１〜４は低い誘電損失を維持しながらＢ特性として実用できる高い誘電率を実現している。しかしながら、ＳｉＯ_２を被覆していない比較例１およびＳｉＯ_２を後から添加した比較例２は高い誘電率を持つ一方で誘電損失も増加してしまい、両特性の両立が不可能であった。また請求の範囲外の比較例３〜５についても同様に誘電損失が増加していることから実用性に乏しい積層セラミックコンデンサとなっている。
【００４１】
また、本発明の積層セラミックコンデンサは主成分のＢａＴｉＯ_３１００重量部に対し、ＳｉＯ_２が０．０１重量部より少量の場合は異常粒成長に対する抑制効果が薄くなるために誘電損失の確保が困難となってしまう。また１．０重量部より多量の場合はＳｉＯ_２のＢａＴｉＯ_３表面への被着が大きくばらついてしまうことからＳｉＯ_２の被覆が不均一となり、余剰のＳｉＯ_２が粒界に偏析するこにより絶縁破壊電圧値を低下させてしまうものである。
【００４２】
次に、図２の結果より、ＳｉＯ_２を被覆した実施例１〜４の絶縁破壊電圧特性は大きく向上しているが、ＳｉＯ_２を被覆していない比較例１およびＳｉＯ_２を後から添加した比較例２は焼結粒子が異常粒成長しているために絶縁破壊電圧特性は著しく低下している。次に粒子径が０．１５μｍのＳｉＯ_２を被覆した比較例３は余剰のＳｉＯ_２が粒界に偏析しているために絶縁抵抗値が低下し、絶縁破壊電圧が低下していた。
【００４３】
また、本発明の請求の範囲外である比較例４，５においても同様に絶縁破壊電圧特性は著しく低下している。
【００４４】
さらに、微細構造を観察するために切断面を研磨した後フッ酸によりエッチングして内部誘電体層の結晶粒子の状態を走査型電子顕微鏡（日本電子社製 ＪＳＭ−５９１０Ｖ）によって観察した。
【００４５】
測定の結果、本発明による実施例１〜４の結晶粒径は０．３〜０．３５μｍであり、特に異常粒成長が見られなかったのに対して比較例１〜５には異常粒成長が顕著に現れ、誘電体層の結晶粒子の粒径は約１．０μｍであった。
【００４６】
以上のように、誘電体材料であるＢａＴｉＯ_３の表面を粒子径０．１μｍ以下のＳｉＯ_２微粒子にて被覆することにより、高い誘電率と低い誘電損失とを両立し、高い絶縁破壊電圧特性を有する信頼性の高い積層セラミックコンデンサの製造方法を提供することができる。
【００４７】
次に、（表２）に示すように希土類元素酸化物であるＤｙ_２Ｏ_３、遷移金属酸化物であるＭｇＯ、ＢａＣＯ_３、ガラス成分であるＢａＳｉＯ_３、ＣａＳｉＯ_３について添加量の検討を行った。これらの添加物は０．１重量部のＳｉＯ_２を被覆した粒子径０．２５μｍのＢａＴｉＯ_３に添加し、上記と同じ方法にて試料を作製した。その結果を（表２）に示す。
【００４８】
【表２】

【００４９】
（表２）の結果から、それぞれの誘電体組成物の副成分である希土類元素酸化物および遷移金属酸化物は０．７重量部以下の添加量において温度特性がＢ特の積層セラミックコンデンサが得られ、より好ましくは０．５重量部以下の添加量によってより優れたＢ特の積層セラミックコンデンサが得られた。
【００５０】
さらに、最高到達温度を１０５０℃にて焼成した試料は焼結性が不十分で、機械的強度が低く実用性に課題を有していた。より低温で焼結させるためには誘電体組成物の粒子径を小さくすることとガラス成分を最適化することによって１２００℃以上であれば実用性を確保することが可能であった。例えば０．１重量部のＳｉＯ_２を被覆した粒子径０．２０μｍのＢａＴｉＯ_３にＤｙ_２Ｏ_３；０．５重量部、ＭｇＯ；０．５重量部、ＢａＳｉＯ_３；０．４重量部、ＢａＣＯ_３；１．２５重量部を配合した誘電体組成にて最高到達温度を１２００℃−３時間の焼成条件にて焼成した試料は誘電率；２５００、温度特性；−８％であった。また０．１重量部のＳｉＯ_２を被覆した粒子径０．３０μｍのＢａＴｉＯ_３にＤｙ_２Ｏ_３；０．５重量部、ＭｇＯ；０．５重量部、ＢａＳｉＯ_３；０．５重量部、ＢａＣＯ_３；０．７５重量部を配合した誘電体組成にて最高到達温度を１４００℃−２時間の焼成条件にて焼成した試料は誘電率；３２００、温度特性；−９％であった。このような特性を有する積層セラミックコンデンサの耐電圧も十分に実用できる焼結性を有していた。
【００５１】
また、最高到達温度を１４５０℃にて焼成を行ったものはショート率が著しく悪化し、良好な特性をもつ試料の歩留まりが著しく低下した。この最高到達温度は誘電体組成物の粒子径に依存するが、特にＢａＴｉＯ_３の粒子径に大きく依存し、高い誘電率と低い誘電損失とを両立させながら温度特性を満足する信頼性の高い積層セラミックコンデンサを得るためには１２００℃〜１４００℃の温度範囲で焼成することが好ましく、より好ましくは１２５０℃〜１３５０℃の範囲であった。
【００５２】
【発明の効果】
以上のように本発明によれば、表面にあらかじめＳｉＯ_２の超微粒子にて被覆したＢａＴｉＯ_３を誘電体組成物の主成分として用いて積層セラミックコンデンサを製造することにより、電気特性および信頼性に優れた積層セラミックコンデンサの製造方法を提供することができるという効果を奏するものである。
【図面の簡単な説明】
【図１】本発明の実施の形態１における積層セラミックコンデンサの誘電率の温度特性を示す特性図
【図２】同積層セラミックコンデンサの誘電体層厚さと絶縁破壊電圧の最頻値との関係を示す特性図[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multilayer ceramic capacitor used for various electronic devices and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, the miniaturization, high performance, and low price of electronic devices have been rapidly progressing, and electronic components such as multilayer ceramic capacitors used in them have been reduced in size, high performance, and low price. Is strongly desired. For miniaturization and high functionality, the material must have a high dielectric constant and low dielectric loss (tan δ), and at the same time control the temperature change of the dielectric constant within the specification range. Attempts have been made to convert noble metals such as Pt and Pd used for internal electrodes into inexpensive base metals such as Ni.
[0003]
Conventional multilayer ceramic capacitors are manufactured by the following method.
[0004]
First, a dielectric composition is obtained by blending an additive with a dielectric material as a main component so as to have a predetermined composition, and then mixing with a ball mill or the like.
[0005]
Thereafter, the dielectric composition and an organic binder, a plasticizer, etc. are added to a dispersion medium such as water or an organic solvent and mixed to form a slurry, and then formed into a dielectric green sheet having a desired thickness by a doctor blade method or the like. .
[0006]
An internal electrode pattern is formed on the dielectric green sheet thus obtained, and one end of each internal electrode pattern is alternately pulled out from the opposing end faces, and a plurality of layers are stacked so that each end face can be connected in parallel. Get. Thereafter, the obtained laminate is cut, degreased / fired, and thereafter, an external electrode is formed as an electrode terminal to manufacture the laminate.
[0007]
An inexpensive base metal such as nickel has come to be used for an internal electrode serving as an electrode of this multilayer ceramic capacitor.Nickel oxidizes when heated in an oxidizing atmosphere, and becomes a dielectric composition. Since the reaction makes it impossible to form an internal electrode, the main component dielectric material itself has reduction resistance by adding various additives so that the main component dielectric material is not reduced even in a reducing atmosphere. Attempts have been made to reduce the sintering temperature and to lower the temperature.
[0008]
As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
[0009]
[Patent Document 1]
JP-A-5-78166
[Problems to be solved by the invention]
However, when trying to improve the dielectric constant of a conventional multilayer ceramic capacitor, it is desirable to fire at a high sintering temperature.
[0011]
However, in this case, since the dielectric material of the main component causes abnormal grain growth at the same time, a high dielectric constant is achieved, but there is a problem that the dielectric loss and the breakdown voltage characteristics are significantly deteriorated. Was.
[0012]
For this reason, there is a trade-off between increasing the dielectric constant and reducing the dielectric loss or improving the dielectric breakdown voltage characteristic, and it has been difficult to improve each characteristic at a high level.
[0013]
The present invention has been made to solve the above-mentioned problems, and by coating the surface of BaTiO ₃ as a raw material powder with ultrafine particles of SiO ₂ in advance, suppresses abnormal grain growth occurring during sintering and maintains reliability. In addition, since the dielectric constant can be improved without impairing the dielectric loss, it is possible to provide a method for manufacturing a multilayer ceramic capacitor having excellent electric characteristics.
[0014]
[Means for Solving the Problems]
According to an aspect of the present invention, there is provided a multilayer ceramic capacitor having a device body in which dielectric layers and internal electrode layers each composed of a dielectric composition are alternately laminated. A multilayer ceramic capacitor using barium titanate having SiO ₂ deposited on the particle surface as a main component of the dielectric composition, wherein the dielectric constant can be improved without a decrease in dielectric breakdown voltage. As a result, it is possible to provide a highly reliable multilayer ceramic capacitor that achieves both low dielectric loss and high dielectric constant.
[0015]
According to a second aspect of the present invention, there is provided the multilayer ceramic capacitor according to the first aspect, comprising fine particles having a particle diameter of SiO ₂ of 0.1 μm or less, and the suppression of abnormal grain growth by coating is more effective. Accordingly, a highly reliable multilayer ceramic capacitor having both low dielectric loss and high dielectric constant can be provided.
[0016]
The invention described in claim 3 of the present invention is a multilayer ceramic capacitor according to claim 1 of the SiO ₂ particles is 0.01 to 1.0 parts by weight with respect to BaTiO ₃ 100 parts by weight, low dielectric It is possible to provide a more reliable multilayer ceramic capacitor that achieves both loss and a high dielectric constant.
[0017]
The invention according to claim 4 of the present invention is the multilayer ceramic capacitor according to claim 1, which comprises a rare earth element oxide, a transition metal oxide, and a glass component as subcomponents of the dielectric composition, and has a dielectric constant temperature. The characteristics can be flattened, and the temperature characteristics can be flattened in addition to the effect of the first aspect.
[0018]
The invention according to claim 5 of the present invention is the multilayer ceramic capacitor according to claim 4, wherein the rare earth element oxide is Dy ₂ O ₃ , which achieves both low dielectric loss and high dielectric constant, and has high reliability. A multilayer ceramic capacitor can be provided.
[0019]
The invention according to claim 6 of the present invention comprises a step of mixing a dielectric composition, a step of slurrying, a step of forming a dielectric green sheet, and an internal electrode formed on the dielectric green sheet. And a sintering step, wherein the laminated ceramic capacitor is made of BaTiO ₃ whose surface is coated with fine particles of SiO ₂ as a main component of the dielectric composition. Alternatively, since BaTiO ₃ can be fired even in a strong reducing atmosphere without abnormal grain growth, the dielectric constant can be improved without a decrease in dielectric breakdown voltage, and both low dielectric loss and high dielectric constant can be achieved. In addition, it is possible to provide a highly reliable method for manufacturing a multilayer ceramic capacitor.
[0020]
The invention according to claim 7 of the present invention is the method for producing a multilayer ceramic capacitor according to claim 6, wherein the maximum temperature in the firing step is 1200 to 1400 ° C, and achieves both low dielectric loss and high dielectric constant. In addition, it is possible to provide a highly reliable multilayer ceramic capacitor manufacturing method capable of realizing a dense sintered body.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a method for manufacturing a multilayer ceramic capacitor of the present invention will be described with reference to embodiments and drawings.
[0022]
(Embodiment 1)
The first embodiment of the present invention and FIGS.
[0023]
FIG. 1 is a characteristic diagram showing a temperature characteristic of a dielectric constant of the multilayer ceramic capacitor according to the first embodiment of the present invention, and FIG. 2 is a characteristic diagram showing a relationship between a thickness of a dielectric layer and a mode of a dielectric breakdown voltage. It is.
[0024]
Next, a method for manufacturing the multilayer ceramic capacitor of the present invention will be described.
[0025]
First, the dielectric material can be obtained by mixing BaTiO ₃ as a main component and rare earth oxides, transition metal oxides, and glass components as additives in predetermined amounts.
[0026]
At this time, a powder obtained by uniformly coating fine particles of SiO _{2 on} the surface of BaTiO ₃ powder having an average particle diameter of 0.3 μm, which is a dielectric material of the main component, under the conditions shown in Table 1 was used. Was. Such BaTiO ₃ powder is obtained by adding a barium salt aqueous solution to a titanium hydroxide colloid, and uniformly coating SiO ₂ in advance with an alkoxide compound of Si using a water glass or the like on the surface of BaTiO ₃ as a main component. It can be manufactured by the following. Examples of the alkoxide compound include methyltriethoxysilane, dimethyldiethoxysilane, tetraethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, tetramethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane , Isobutyltrimethoxysilane, decyltrimethoxysilane and the like.
[0027]
Further, it can also be coated by a surface treatment method comprising a silane coupling agent silicon compound or a negatively chargeable polymer.
[0028]
Furthermore, the addition of hydroxides of Si, it is possible to the SiO ₂ particles coated on the surface of the well BaTiO ₃ particles by using a method for surface deposition by autoclave method by hydrothermal reaction treatment.
[0029]
Next, in order to control the temperature characteristics, the dielectric loss characteristics, and the like, the auxiliary components of the dielectric material as shown in Table 1 are blended. In the first embodiment, the SiO ₂ fine particles are coated so that the temperature characteristic becomes the B characteristic (a capacitor showing a change in capacitance value within ± 10% in a temperature range of −25 ° C. to + 85 ° C.). a main component BaTiO _3, which is, 0.5 parts by weight of _Dy 2 _{O 3} as the rare earth element oxides, 0.5 part by weight of MgO is a transition metal oxide, BaSiO ₃ 0.5 wt a glass component Examples 1 to 4 were prepared in such a manner that the desired dielectric composition was obtained by the addition amount of the parts. It is effective to use Dy ₂ O ₃ , Ho ₂ O ₃ , Y ₂ O _3, or the like as a rare-earth element oxide as a sub-component in an amount of 0.5 part by weight or less based on 100 parts by weight of BaTiO _3. Yes, especially Dy ₂ O ₃ is the most effective additive. Further, it is preferable to add MgO, BaCO _3, or the like as a transition metal oxide at a blending ratio of 0.5 part by weight or less based on 100 parts by weight of BaTiO ₃ . As the glass component, it is preferable to use BaSiO ₃ , CaSiO _3, or the like in a mixing ratio of 1 part by weight or less based on 100 parts by weight of BaTiO ₃ .
[0030]
Further, a dielectric composition using BaTiO ₃ having no SiO ₂ coating layer on the particle surface was used as Comparative Example 1, and the same amount of SiO ₂ as in Example 1 was blended as an additive in the blending step to obtain a dielectric composition. The product was designated as Comparative Example 2. Further, Comparative Example 3 was made of barium titanate having an average particle diameter of 0.3 μm uniformly coated with fine particles of SiO _{2 having} a particle diameter of 0.15 μm.
[0031]
Further, by changing the concentration of the Si compound content in the liquid phase, BaTiO ₃ in which fine particles of SiO ₂ were coated at a ratio of 0.005 parts by weight and 1.5 parts by weight with respect to 100 parts by weight of BaTiO ₃ was produced. Comparative Examples 4 and 5 were made.
[0032]
Next, 30 parts by weight of butyl acetate as a dispersion medium is added to 100 parts by weight of the dielectric composition, and 500 parts by weight of a zirconia cobblestone having a diameter of 10 mm are added. The dielectric composition, the dispersion medium and the cobblestone blended as described above are placed in a ball mill and mixed for 12 hours.
[0033]
Thereafter, 9 parts by weight of a butyral resin-based binder (BM-S manufactured by Sekisui Chemical Co., Ltd.) as a binder and benzyl phthalate as a plasticizer were added to 100 parts by weight of the powder of the dielectric composition containing the dispersion medium mixed in the ball mill. After adding 4.5 parts by weight of butyl, this mixture was sufficiently dispersed by a medium stirring mill or the like to form a slurry, thereby obtaining a dielectric slurry.
[0034]
Next, the dielectric slurry was formed into a dielectric green sheet having a thickness of 2.5 μm by a doctor blade method or the like. An internal electrode pattern is printed and formed on the thus obtained dielectric green sheet by using a nickel electrode paste, and one end of each internal electrode is alternately pulled out from the opposing end faces so that the respective opposing end faces can be connected in parallel. Then, 25 dielectric layers and 25 electrode layers were laminated to obtain a 25-layer laminate.
[0035]
Thereafter, the obtained laminate is subjected to a binder removal treatment in an N ₂ atmosphere at 450 ° C., and then fired at a temperature of 1350 ° C. in a reducing atmosphere in which nickel of the internal electrode is not oxidized. After the electrodes were formed with a nickel electrode paste, copper and solder electrodes were formed on the nickel electrodes by plating to enhance solder wettability, thereby obtaining a chip-shaped multilayer ceramic capacitor.
[0036]
The dielectric constant and dielectric loss, which are the electrical characteristics of the multilayer ceramic capacitor thus obtained, were measured using an LCR meter (4284A manufactured by Agilent) under the conditions of 1.0 kHz and 1.0 Vrms.
[0037]
The dielectric breakdown voltage was obtained by applying a DC power supply voltage (PADIK-0.2L manufactured by Kikusui) to both electrodes of the multilayer ceramic capacitor, and measuring the voltage at the time of dielectric breakdown with an oscilloscope (TDS210 manufactured by Tektronix). The electrical characteristics of each of the manufactured multilayer ceramic capacitors are shown in (Table 1), and the temperature characteristics of the dielectric constant at that time are shown in FIG.
[0038]
FIG. 2 shows the relationship between the thickness of the dielectric layer and the mode of the dielectric breakdown voltage in the multilayer ceramic capacitor.
[0039]
[Table 1]

[0040]
As is clear from the results shown in Table 1 and FIG. 1, Examples 1 to 4 according to the present invention realize a high dielectric constant that can be used as the B characteristic while maintaining a low dielectric loss. However, Comparative Example were added later Comparative Example 1 and SiO ₂ does not cover the SiO ₂ 2 One dielectric loss will be increased with a high dielectric constant, both of the two properties was impossible. In Comparative Examples 3 to 5 outside the scope of the claims, the dielectric loss is similarly increased, so that the multilayer ceramic capacitor is less practical.
[0041]
Further, in the multilayer ceramic capacitor of the present invention, when SiO ₂ is less than 0.01 part by weight with respect to 100 parts by weight of BaTiO _{3 as a} main component, the effect of suppressing abnormal grain growth becomes thin, so that it is difficult to secure dielectric loss. Will be. In the case of larger amounts 1.0 parts by weight makes the coating of SiO ₂ is not uniform since the deposition of the BaTiO ₃ surface of the SiO ₂ resulting in large variations, insulated by this the SiO ₂ excess is segregated in the grain boundary This will lower the breakdown voltage value.
[0042]
Next, from the results of FIG. 2, the dielectric breakdown voltage characteristics of Examples 1 to 4 were coated with SiO ₂ is greatly improved, but added later Comparative Example 1 and SiO ₂ does not cover the SiO ₂ In Comparative Example 2, the dielectric breakdown voltage characteristics were remarkably deteriorated because the sintered particles grew abnormally. Next, in Comparative Example 3 coated with SiO ₂ having a particle size of 0.15 μm, the excess SiO ₂ was segregated at the grain boundaries, so that the insulation resistance value was lowered and the dielectric breakdown voltage was lowered.
[0043]
Also, in Comparative Examples 4 and 5, which are outside the scope of the present invention, the breakdown voltage characteristics are also significantly reduced.
[0044]
Further, in order to observe the fine structure, the cut surface was polished and then etched with hydrofluoric acid, and the state of the crystal grains of the internal dielectric layer was observed with a scanning electron microscope (JSM-5910V manufactured by JEOL Ltd.).
[0045]
As a result of the measurement, the crystal grain sizes of Examples 1 to 4 according to the present invention were 0.3 to 0.35 μm. In particular, no abnormal grain growth was observed, whereas Comparative Examples 1 to 5 showed abnormal grain growth. Remarkably appeared, and the crystal grain size of the dielectric layer was about 1.0 μm.
[0046]
As described above, by coating the surface of BaTiO ₃ as a dielectric material with fine particles of SiO ₂ having a particle diameter of 0.1 μm or less, a high dielectric constant and a low dielectric loss are compatible, and a high dielectric breakdown voltage characteristic is obtained. Thus, it is possible to provide a highly reliable method for manufacturing a multilayer ceramic capacitor.
[0047]
Next, as shown in (Table 2), the amount of addition was examined for Dy ₂ O ₃ which is a rare earth element oxide, MgO and BaCO ₃ which are transition metal oxides, and BaSiO ₃ and CaSiO ₃ which are glass components. . These additives were added to BaTiO ₃ coated with 0.1 part by weight of SiO ₂ and having a particle diameter of 0.25 μm, and samples were prepared in the same manner as described above. The results are shown in (Table 2).
[0048]
[Table 2]

[0049]
From the results shown in Table 2, a rare-earth element oxide and a transition metal oxide, which are subcomponents of each dielectric composition, were obtained at a content of 0.7 parts by weight or less to obtain a multilayer ceramic capacitor having a temperature characteristic of B. More preferably, with an addition amount of 0.5 part by weight or less, a more excellent B-specific multilayer ceramic capacitor was obtained.
[0050]
Furthermore, the sample fired at a maximum temperature of 1050 ° C. had insufficient sinterability, low mechanical strength, and had a problem in practicality. For sintering at a lower temperature, practicality can be ensured at 1200 ° C. or higher by reducing the particle diameter of the dielectric composition and optimizing the glass component. For example, 0.5 parts by weight of Dy ₂ O _3, 0.5 parts by weight of MgO, 0.4 parts by weight of BaSiO _3, 0.4 parts by weight of BaCO ₃ are coated on BaTiO ₃ having a particle diameter of 0.20 μm coated with 0.1 parts by weight of SiO _{2. 3.} A sample fired under the firing condition of 1200 ° C. for 3 hours with a dielectric composition containing 1.25 parts by weight had a dielectric constant of 2500 and a temperature characteristic of −8%. The _Dy 2 _O 3 to BaTiO ₃ particle size 0.30μm coated with SiO ₂ of 0.1 parts by weight; 0.5 parts by weight, MgO: 0.5 parts by weight, BaSiO _3; 0.5 parts by weight, BaCO ₃ : A sample fired under the firing condition of a maximum temperature of 1400 ° C. for 2 hours with a dielectric composition containing 0.75 parts by weight had a dielectric constant of 3200 and a temperature characteristic of −9%. The multilayer ceramic capacitor having such characteristics has a sintering property capable of sufficiently withstanding the withstand voltage.
[0051]
In the case of firing at a maximum temperature of 1450 ° C., the short-circuit rate was remarkably deteriorated, and the yield of samples having good characteristics was significantly lowered. This maximum temperature depends on the particle size of the dielectric composition, but in particular greatly depends on the particle size of BaTiO ₃ , and a highly reliable laminate satisfying temperature characteristics while achieving both high dielectric constant and low dielectric loss. In order to obtain a ceramic capacitor, firing is preferably performed at a temperature in the range of 1200 to 1400 ° C, and more preferably 1250 to 1350 ° C.
[0052]
【The invention's effect】
As described above, according to the present invention, a multilayer ceramic capacitor is manufactured by using BaTiO _3, whose surface is previously coated with ultrafine particles of SiO ₂ , as a main component of a dielectric composition, thereby improving electrical characteristics and reliability. An advantage is that an excellent method for manufacturing a multilayer ceramic capacitor can be provided.
[Brief description of the drawings]
FIG. 1 is a characteristic diagram showing a temperature characteristic of a dielectric constant of a multilayer ceramic capacitor according to a first embodiment of the present invention. FIG. 2 is a graph showing a relationship between a dielectric layer thickness and a mode of a dielectric breakdown voltage of the multilayer ceramic capacitor. Characteristic diagram shown

Claims (7)

A multilayer ceramic capacitor having an element body in which dielectric layers and internal electrode layers made of a dielectric composition are alternately stacked, wherein the barium titanate having SiO ₂ adhered to the particle surface is formed by the above-described method. A multilayer ceramic capacitor used as a main component of a dielectric composition. The multilayer ceramic capacitor according to claim 1 having a particle diameter of SiO ₂ is composed of the following fine 0.1 [mu] m. The multilayer ceramic capacitor according to claim 1 of the SiO ₂ particles is 0.01 to 1.0 parts by weight with respect to BaTiO ₃ 100 parts by weight. 2. The multilayer ceramic capacitor according to claim 1, wherein the dielectric composition contains a rare earth element oxide, a transition metal oxide, and a glass component as auxiliary components. 3. The multilayer ceramic capacitor according to claim 4 rare earth oxide is Dy ₂ O _3. A multilayer ceramic comprising a step of blending a dielectric composition, a step of slurrying, a step of forming a dielectric green sheet, a step of laminating a dielectric green sheet having internal electrodes formed thereon, and a firing step A method for manufacturing a multilayer ceramic capacitor, wherein BaTiO ₃ whose surface is coated with fine particles of SiO ₂ is used as a main component of a dielectric composition. The method for producing a multilayer ceramic capacitor according to claim 6, wherein the maximum temperature in the firing step is 1200 to 1400C.

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