JP3600701B2 - Dielectric porcelain composition - Google Patents

Description

【００３３】
【表２】

【００３４】
次いで、前記混合粉砕物に有機系粘結剤と媒体から成るバインダーを添加して攪拌してセラミック泥漿を調製した後、得られたセラミック泥漿を脱泡し、該泥漿を用いてドクターブレード法によりフィルムキャリア上に厚さ約４０μｍのグリーンシートを成形した。
【００３５】
得られたグリーンシートを縦１３０ｍｍ、横１００ｍｍの矩形状に裁断し、該矩形状シートを４０枚重ねた後、８０℃の温度でホットプレスして厚さ約１ｍｍの積層体を作製し、該積層体を直径２０ｍｍの円板状に打ち抜き、大気中、１２１０〜１３４０℃の範囲の各温度で２時間焼成した。
【００３６】
その後、円板状焼結体の両端面に銀ペーストを用いて電極を焼付け、評価用試料とした。
【００３７】
かくして得られた評価用試料を用い、先ず、基準温度２５℃、周波数１．０ｋＨｚ、測定電圧１．０Ｖｒｍｓの測定条件で、前記評価用試料の比誘電率εｒ及び誘電損失ｔａｎδを測定し、更に、直流電圧５０Ｖを１分間印加した時の絶縁抵抗ＩＲを測定した。
【００３８】
測定結果から、比誘電率εｒが１５０００未満では、例えば積層型セラミックコンデンサでは小型化ができないため、１５０００以上を良とし、更に、誘電損失ｔａｎδは、１．０％以上になると、例えばコンデンサのチップ化が困難となる等のため、１．０％未満を良と評価した。一方、絶縁抵抗ＩＲは、１．０×１０^５ ＭΩ未満では、積層型セラミックコンデンサとして絶縁抵抗の規格を満足せず、絶縁不良となるため、１．０×１０^５ ＭΩ以上を良と評価した。
【００３９】
更に、アルキメデス法で密度を測定し、該密度が５．７ｇ／ｃｍ^３ 以下ではこれら高誘電率系の誘電体磁器組成物は焼成不十分であることを示しており、１３００℃未満の低温焼成で実用的な焼結体が得られないことから、密度は５．７ｇ／ｃｍ^３ 以上を良と評価した。以上の結果を、表３、４に示す。
【００４０】
【表３】

【００４１】
【表４】

【００４２】
表３、４から明らかなように、試料番号８、９、１５、１６、２２、２９、４４、４５では、積層セラミックコンデンサ等の小型・大容量化に大きく寄与する比誘電率が１４０００以下と低くなっており、試料番号８、１６、２９、３９、４５、５２は、いずれも焼成温度が１３１０℃以上となっている。
【００４３】
また、試料番号９、２３、２８、２９、３８は、誘電損失が１．１５％以上と大きく、試料番号１６、２９、４５、５２では、焼成温度を１３１０〜１３２０℃とかなり高い温度で焼成しても密度が５．７０ｇ／ｃｍ^３ 未満と低く焼結不足となっている。
【００４４】
更に、試料番号２２、２８、５２は、いずれも絶縁抵抗が１．０×１０^５ 未満と低くなっている。
【００４５】
それに対して、本願発明の試料番号のものは、いずれも比誘電率も１５２００以上と高く、焼成温度は１２９０℃以下と低く、誘電損失も０．９３％以下、密度は５．７２ｇ／ｃｍ^３ 以上、更に絶縁抵抗も２．４×１０^５ ＭΩ以上といずれの要求特性をも満足するものになっている。
【００４６】
次に、表１，２に示す組成で上記と同様にして調製したセラミック泥漿を用いて成形した厚さ１０μｍの各グリーンシート上に、銀−パラジウム（Ａｇ−Ｐｄ）粉末から成る内部電極用ペーストを用いて電極を所定形状にスクリーン印刷した後、該電極を印刷したグリーンシートをそれぞれ２０枚積層してホットプレスして一体化し、所定寸法に切断してグリーンチップを作製した。
【００４７】
得られたグリーンチップを大気中、４００℃の温度で２時間保持してバインダーを完全に分解して脱バインダーした後、それぞれ各組成に対応した表３，４に示す焼成温度で、２時間保持して焼成した。
【００４８】
その後、焼結したチップに銀−パラジウム（Ａｇ−Ｐｄ）から成る外部取り出し電極を焼き付け、評価用のチップコンデンサを作製した。
【００４９】
尚、前記評価用チップコンデンサの誘電体層一層の厚さは、いずれも平均８μｍであり、有効電極面積は１．２ｍｍ^２ であった。
【００５０】
かくして得られた評価用チップコンデンサを用い、先ず、基準温度２５℃、周波数１．０ｋＨｚ、測定電圧１．０Ｖｒｍｓの測定条件で、前記評価用チップコンデンサの静電容量及び誘電損失を測定するとともに、基準温度２５℃の静電容量に対する−３０℃から＋８５℃までの温度における静電容量の温度変化率を測定した。さらに、８５℃で電界強度が１．２×１０^４ Ｖ／ｍｍの直流電圧の印加状態を保つ高温負荷試験を行った。この高温負荷試験は、３００個の評価用チップコンデンサについて行い、最初にショートとしたチップコンデンサの、印加開始からショートに至るまでの時間を測定することにより行った。
【００５１】
また、表３，４に示した比誘電率と、焼結後の評価用チップコンデンサの内部電極面積、内部電極の間隔及び積層数等から算出した設計容量に対する、前記評価用チップコンデンサの測定容量の比を容量比率とした。
【００５２】
更に、前記評価用チップコンデンサの磁器表面を無作為に５箇所選び、これらを走査型電子顕微鏡で８００倍に拡大して撮影し、これらの写真から２００個の結晶粒子をランダムに選んで切片法により大きさを測定し、平均値を求めて平均粒径とした。さらに異常粒成長が発生しているか、否かも確認した。この異常粒成長の判定は、平均粒径の５倍以上の粒子が存在していれば、異常粒成長していると判定した。
【００５３】
以上の測定結果から、静電容量の値は、２００ｎＦ未満では積層型セラミックコンデンサとして小型化が困難なことから、２００ｎＦ以上を良と評価した。
【００５４】
また、誘電損失が５．０％以上になると積層型セラミックコンデンサとして実用的でないため、その値は５．０％未満を良とした。
【００５５】
更に、容量比率が７０％未満になると、積層型セラミックコンデンサとして充分な容量が得られず、小型化が困難なことから、７０％以上を良とした。
【００５６】
高温負荷試験は、４０時間未満に不良が発生した場合、積層型セラミックコンデンサの規格を満足しなくなることから、４０時間以上不良が発生しないことを良とした。
【００５７】
平均粒径が８．０μｍ以上になると、誘電体層一層厚みが１０μｍ以下の積層セラミックコンデンサの高温負荷寿命が規格を満足しなくなることから、８．０μｍ以下を良とした。これらの結果を表５、６に記載する。
【００５８】
【表５】

【００５９】
【表６】

【００６０】
表５，６から明らかなように、試料番号１では温度特性が規格外となり、規格に適合しても例えば、試料番号８、９、１５、１６、２９、４４、４５は、いずれも静電容量が２００ｎＦ未満と小さく、積層型セラミックコンデンサの小型化が実現できない。
【００６１】
また、試料番号９、２３、２８、２９、３８は、誘電損失が５．２％以上となって実用範囲外となっている。
【００６２】
また、試料番号２９は、異常粒成長が認められ、容量比率も７０％未満と小さく誘電体層一層の厚さが１０μｍ以下という薄板化は困難である。
【００６３】
試料番号２９、３９は、平均粒径が８．０μｍ以上となっており、誘電体層一層厚みが１０μｍ以下の積層セラミックコンデンサの高温負荷試験が規格を満足しなくなる。
【００６４】
それに対して、本願発明の試料番号のチップコンデンサは、いずれも静電容量が２１１ｎＦ以上と高く、焼成温度も１２９０℃以下と低く、かつ誘電損失も４．３％以下と小さく、容量比率は８４％以上を有し、異常粒成長が全く認められないものであることが分かる。
【００６５】
【発明の効果】
叙上の如く、本発明の誘電体磁器組成物は、チタンスズ酸バリウムカルシウムから成る複合酸化物を主成分とし、該主成分に希土類元素化合物及び亜鉛化合物、マンガン化合物、チタン化合物、さらに珪素化合物を含有させたことから、ＥＩＡ規格のＹ５Ｖ特性を満足するとともに、比誘電率が１５０００以上、高温負荷寿命が長く、１３００℃未満の低温焼成が可能で、厚さ１０μｍ以下の薄板表面が平滑で緻密なシート状焼結体を得ることができることから、安価な内部電極材料を用いた小型・大容量の積層型セラミックコンデンサをはじめ、各種コンデンサに適用できる誘電体磁器組成物を得ることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-permittivity dielectric ceramic composition for forming a thin plate that can be fired at a low temperature, and particularly relates to a high-permittivity ceramic capacitor and a multilayer ceramic capacitor having excellent temperature characteristics of capacitance, and furthermore, The present invention relates to a dielectric ceramic composition suitable as a dielectric material for axial capacitors, disk capacitors, thick film capacitors, and the like.
[0002]
[Prior art]
Conventionally, as a dielectric material used for a high dielectric constant type ceramic capacitor and a multilayer ceramic capacitor, there is a barium titanate (BaTiO ₃ ) type dielectric ceramic composition having a relative dielectric constant of about 6,000 to 10,000. The dielectric ceramic composition has been widely applied to multilayer ceramic capacitors from the viewpoint of electric capacity.
[0003]
In the multilayer ceramic capacitor, an electrode is generally formed on a green sheet made of a dielectric ceramic composition, a plurality of the green sheets are stacked so as to have a predetermined electric capacity, and the electrodes are simultaneously fired and integrated to form an internal electrode. An electrode is configured.
[0004]
However, the barium titanate (BaTiO ₃ ) -based dielectric porcelain composition has a firing temperature as high as about 1300 to 1400 ° C. In addition, in order to use the dielectric ceramic composition as a dielectric material of a multilayer ceramic capacitor, it is necessary to simultaneously sinter it. As the electrode material, palladium (Pd) or platinum (Pt), which is a noble metal having a high melting point and high temperature reducibility, must be used, and it is difficult to manufacture a low-cost, small-sized, large-capacity multilayer ceramic capacitor. There was a disadvantage.
[0005]
Therefore, in order to solve the drawback, conventionally, a dielectric material having a relative dielectric constant as high as 10,000 or more is used, the sheet thickness of the dielectric ceramic composition between the internal electrodes is reduced to about 30 μm, In addition to minimizing the area to reduce the size of the multilayer ceramic capacitor, it has been possible to replace the internal electrode material with the inexpensive Ag-Pd or the like from the expensive noble metal so as to enable low-temperature firing.
[0006]
As such a dielectric material, a predetermined amount of barium stannate (BaSnO ₃ ), calcium titanate (CaTiO ₃ ), cobalt oxide (CoO), manganese oxide (MnO ₂ ), or the like is added to barium titanate (BaTiO ₃ ). A predetermined amount of lead titanate (PbTiO ₃ ), lead germanate (Pb ₅ Ge ₃ O ₁₁ ), titanium dioxide is added to the obtained dielectric ceramic composition or barium titanate (BaTiO ₃ ) or calcium zirconate (CaZrO ₃ ). bismuth (Biti ₂ O ₇₎ dielectric ceramic composition obtained by adding or the like has been known (JP-B 60-57164, JP-see JP-B-61-16132).
[0007]
In such a dielectric ceramic composition, the relative dielectric constant at room temperature is as high as about 10,000 to 20,000, and low-temperature firing at 1200 ° C. or lower can be realized.
[0008]
[Problems to be solved by the invention]
In electronic components that are being downsized, it has become necessary to reduce the thickness of a sheet-shaped sintered body made of a dielectric ceramic composition in order to achieve smaller size and higher capacity. Has become smaller than 10 μm.
[0009]
However, there is a problem that the dielectric strength between the pair of electrodes is reduced when the dielectric layer is thinned.
[0010]
As another method for increasing the capacitance, there is a method using a porcelain having a high relative dielectric constant. However, the above-described conventional BaTiO ₃ -based dielectric porcelain has a limit in the relative dielectric constant, and thus has a high dielectric constant. There was a limit to capacity.
[0011]
Further, when a multilayer capacitor composed of a thin layer having a thickness of 10 μm or less is manufactured using the dielectric material, a DC voltage having an electric field intensity of 1.2 × 10 ⁴ V / mm at 85 ° C. is applied. The high-temperature load life is as short as less than 40 hours, and the rate of change of the capacitance in the temperature range of -30 ° C to + 85 ° C is extremely large, from -90% to + 95%. Cannot satisfy the EIA standard Y5V characteristic in which the rate of change is within -82% to + 22%, and it is not possible to obtain such various types of capacitors including small-sized and large-capacity multilayer ceramic capacitors. was there.
[0012]
The present invention provides a thin plate-shaped sintered body having a smooth surface with a thickness of 10 μm or less at a low temperature of 1300 ° C. or higher, with a relative dielectric constant as high as 15,000 or more at room temperature, and an inexpensive internal electrode. Of course, the material can be used, and the high-temperature load life is as long as 40 hours or more, and the Y5V characteristic that the rate of change of capacitance in the temperature range of -30 ° C to + 85 ° C is within -82% to + 22% is satisfied. It is an object of the present invention to provide a dielectric ceramic composition applicable to various types of capacitors, including small and large-capacity multilayer ceramic capacitors.
[0013]
[Means for Solving the Problems]
The dielectric ceramic composition of the present invention contains at least Ba, Ca, Ti, and Sn as metal elements, and a composition formula based on a molar ratio of these metal element oxides is (Ba _1-x Ca _x ) (Ti _{1- y} Sn _y ) O ₃ , where x and y satisfy 0.01 ≦ x ≦ 0.10 and 0.04 <y <0.10, respectively, and 100 parts by weight of the main component. in contrast, a zinc compound 0.1 to 0.9 parts by weight calculated as ZnO, 0.1 to 0.5 parts by weight of a manganese compound with MnO ₂ in terms of the titanium compound in terms of TiO ₂ 0.1-1.3 Parts by weight, 0.05 to 0.20 parts by weight of silicon compound in terms of SiO ₂ , and rare earth element compounds of Nd ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ , La ₂ O ₃ , Pr ₆ O ₁₁ , CeO ₂ , at least one of Tb ₄ O ₇ and Eu ₂ O ₃ 0.8 to 1.8 parts by weight in terms of seed (however, not including Bi ₂ O ₃ and Nb ₂ O ₅ ) .
[0014]
[Action]
According to the dielectric ceramic composition of the present invention, a predetermined amount of the barium calcium stannate complex oxide expressed by the composition formula (Ba _1-x Ca _x ) (Ti _1-y Sn _y ) O ₃ is used. Since it contains a zinc compound, a manganese compound, a titanium compound, a silicon compound, and a rare earth element compound, while maintaining a relative dielectric constant of 15,000 or more, and enabling low-temperature firing at less than 1300 ° C., from a thin layer having a thickness of 10 μm or less. With such a multilayer capacitor, the above-mentioned Y5V characteristics can be satisfied. In particular, the above properties can be improved by including an excessive amount of a titanium compound.
[0015]
As a result, the dielectric loss tan δ, which is a basic characteristic of the dielectric ceramic composition, is 1.0% or less, the insulation resistance IR is 1.0 × 10 ⁵ MΩ or more, and the electric field strength is 1.2 at 85 ° C. In a high-temperature load test in which a DC voltage of × 10 ⁴ V / mm was applied, no failure occurred for 40 hours or more, and the firing temperature was less than 1300 ° C., making it easy to produce industrially, and a dielectric material applicable to various ceramic capacitors. A body porcelain composition is obtained. In particular, in the present invention, by containing 0.05 to 0.2 parts by weight of SiO ₂ , the electric field intensity is 40 hours in a high-temperature load test in which a DC voltage of 1.2 × 10 ⁴ V / mm is applied at 85 ° C. As described above, the defect hardly occurs.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
In the dielectric ceramic composition of the present invention, the composition formula _{(Ba 1-x Ca x)} (Ti 1-y Sn y) when expressed as _{O 3,} x, y is 0.01 ≦ x ≦ respectively 0.10 , 0.04 <y <0.10.
[0017]
_{Here, (Ba 1-x Ca x} ) (Ti 1-y Sn y) O 3 composite oxide consisting Chitansuzu barium calcium represented by is preferably 99.0% or more purity. The reason why x and y are limited as described above is that when the mole fraction x is less than 0.01, the temperature characteristic of the capacitance does not satisfy the Y5V characteristic, and the mole fraction x is 0.10. If it exceeds, or if the molar fraction y is 0.04 or less or 0.10 or more, the relative dielectric constant εr at room temperature becomes as small as less than 15,000.
[0018]
Therefore, in order to satisfy various Y5V characteristics, maintain a high relative dielectric constant of 15,000 or more, and obtain various capacitors including small-sized and large-capacity multilayer capacitors, the value of x is 0.01 to 0.10. , Y are specified to be more than 0.04 and less than 0.10, and particularly, the value of x is preferably in the range of 0.03 to 0.07, and the value of y is preferably in the range of 0.06 to 0.08.
[0019]
The zinc compound adjusts the firing temperature and the relative dielectric constant of the dielectric ceramic composition. When the content is less than 0.1 part by weight with respect to 100 parts by weight of the main component, the firing temperature is 1300. ° C or higher, the relative dielectric constant εr at room temperature is reduced to less than 15000, and the density of the fired sheet-like sintered body is reduced to 5.7 g / cm ³ or less, which is outside the practical range. If it exceeds 0.9 parts by weight, the relative dielectric constant ε at room temperature will be as low as less than 15000, the insulation resistance IR will be greatly reduced, and the density of the sintered sheet after firing will be 5.7 g / cm ³ or less. , Which is out of the practical range, so that it is specified in the range of 0.1 to 0.9 part by weight, and more preferably 0.3 to 0.5 part by weight.
[0020]
Further, the manganese compound improves, for example, the dielectric loss tan δ of the dielectric ceramic composition, and its content is 0.1 manganese oxide (MnO ₂ ) in terms of manganese oxide (MnO ₂ ) with respect to 100 parts by weight of the main component. If the amount is less than 1 part by weight, the dielectric loss tan δ is as large as 1% or more, and if it exceeds 0.5 part by weight, the insulation resistance IR is greatly reduced.
[0021]
Therefore, the content of the manganese compound is limited to 0.1 to 0.5 part by weight, and particularly to 0.2 to 0.3 part by weight, in terms of manganese oxide (MnO ₂ ) based on 100 parts by weight of the main component. Parts by weight are desirable.
[0022]
On the other hand, the titanium compound is included, for example, to improve the sinterability of the dielectric ceramic composition, and the amount of the titanium compound is calculated as titanium oxide (TiO ₂ ) per 100 parts by weight of the main component. If the amount is less than 0.1 part by weight, the firing temperature becomes 1300 ° C. or more, the density of the sintered sheet after firing becomes as low as 5.7 g / cm ³ or less, and the dielectric loss tan δ becomes as large as 1% or more. When the content exceeds 1.3 parts by weight, the dielectric loss tan δ exceeds 1.0%. Therefore, the content is specified to be 0.1 to 1.3 parts by weight, which is more preferable. Is in the range of 0.2 to 1.2 parts by weight.
[0023]
The silicon compound adjusts the crystal grain size of the dielectric porcelain composition. When the content is less than 0.05 part by weight in terms of SiO _{2 with} respect to 100 parts by weight of the main component, the silicon compound is heated at 85 ° C. In a high-temperature load test in which a DC voltage of 1.2 × 10 ⁴ V / mm is applied, defects easily occur within 40 hours, and the firing temperature becomes 1300 ° C. or more, which is outside the practical range. If it exceeds 0.20 parts by weight, the relative dielectric constant will be reduced to less than 15,000, which is out of the practical range. Therefore, the content is specified to be 0.05 to 0.20 parts by weight, which is more preferable. Is 0.10 to 0.15 parts by weight.
[0024]
Further, the rare earth element compound is added to improve the sinterability of the dielectric ceramic composition and to increase the relative dielectric constant. Nd ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ , La ₂ O ₃ , Pr ₆ O ₁₁ , CeO ₂ , Tb ₄ O ₇ , Eu ₂ O ₃ ). If the dielectric constant is reduced to less than 15,000, and if it exceeds 1.8 parts by weight, the density and insulation resistance IR of the sheet-shaped sintered body are lowered and fall outside the practical range. It is specified in the range of 0.8 to 1.8 parts by weight, more preferably 1.0 to 1.6 parts by weight. As the rare earth element, Nd ₂ O ₃ is desirable from the viewpoint of improving sinterability and relative dielectric constant.
[0025]
Manganese compounds include those represented by MnO ₂ and MnCO ₃ , and rare earth element compounds include those represented by Re ₂ O ₃ , Re ₆ O ₁₁ , ReO ₂ , and Re ₄ O ₇ .
[0026]
In the dielectric ceramic composition of the present _invention, the _{(Ba 1-x Ca x)} (Ti 1-y Sn y) O 3 is intended to a main crystal, Zn, Mn, Ti, Si, rare earth elements mainly It exists as glass at the grain boundaries of the main crystal. Zn, Mn, Ti, Si, and rare earth elements may form a solid solution in the main crystal. The average crystal grain size of the main crystal is desirably 4.0 to 7.5 μm from the viewpoint of improving the high relative dielectric constant and the high temperature load life.
[0027]
In the dielectric ceramic composition of the present invention, SrO, Na ₂ O, Fe ₂ O _{3 and the} like may be mixed as unavoidable impurities, and Al ₂ O ₃ and ZrO ₂ may be mixed from the pulverized balls. There is also.
[0028]
The dielectric ceramic composition of the present invention, for example, as a starting material, barium titanate oxide, Zuzu, composite oxide consisting of calcium _{oxide, (Ba 1-x Ca x} ) (Ti 1-y Sn y) O 3 powder And a zinc compound powder such as ZnO, a manganese compound powder such as MnO ₂ , a titanium compound powder such as TiO ₂ , a silicon compound powder such as SiO ₂ and Nd _{2 with} respect to 100 parts by weight of the main component. A predetermined amount of each of the rare earth element compound powders such as O ₃ is weighed and mixed and pulverized by a ball mill.
[0029]
Next, after adding a binder composed of an organic binder and a medium to the mixed and pulverized material and stirring to prepare a ceramic slurry, for example, the obtained ceramic slurry is defoamed, and a doctor blade is used using the slurry. A green sheet is formed by the method.
[0030]
The obtained green sheet is cut into a predetermined shape, a predetermined number of the sheets are laminated, and fired at a temperature of 1200 to 1300 ° C. for 0.5 to 5 hours in an oxidizing atmosphere such as the air.
[0031]
【Example】
As a starting material, (Ba _1-x Ca _x ) (Ti ₁₋ ) having a mole fraction x of 0.01 to 0.10, a mole fraction y of 0.04 to 0.10 and an average particle size of 1 μm or less. and Chitansuzu barium calcium mainly composed of _y Sn _{y) O 3,} relative to the 100 parts by weight of the main component, zinc oxide (ZnO), manganese compounds, titanium compounds, silicon dioxide (SiO ₂₎ and a rare earth element oxide The manganese compound is manganese oxide (MnO ₂ ), the titanium compound is titanium oxide (TiO ₂ ), and the rare earth oxides are oxides (Nd ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ , (La ₂ O ₃ , Pr ₆ O ₁₁ , CeO ₂ , Tb ₄ O ₇ , Eu ₂ O ₃ ), and weighed so as to obtain the weight parts shown in Tables 1 and 2, and then powdered the ZrO ₂ balls. Ball ball used At 20 hours wet-mixed and pulverized.
[0032]
[Table 1]

[0033]
[Table 2]

[0034]
Next, after adding a binder comprising an organic binder and a medium to the mixed and pulverized material and stirring to prepare a ceramic slurry, the obtained ceramic slurry is defoamed, and a doctor blade method is performed using the slurry. A green sheet having a thickness of about 40 μm was formed on a film carrier.
[0035]
The obtained green sheet was cut into a rectangular shape having a length of 130 mm and a width of 100 mm. After stacking 40 such rectangular sheets, a hot press was performed at a temperature of 80 ° C. to produce a laminate having a thickness of about 1 mm. The laminate was punched into a disc having a diameter of 20 mm and fired in the atmosphere at each temperature in the range of 1210 to 1340 ° C. for 2 hours.
[0036]
Thereafter, electrodes were baked on both end surfaces of the disc-shaped sintered body using a silver paste to obtain evaluation samples.
[0037]
Using the evaluation sample thus obtained, first, under the measurement conditions of a reference temperature of 25 ° C., a frequency of 1.0 kHz, and a measurement voltage of 1.0 Vrms, the relative dielectric constant εr and the dielectric loss tanδ of the evaluation sample were measured. The insulation resistance IR when a DC voltage of 50 V was applied for one minute was measured.
[0038]
From the measurement results, when the relative dielectric constant εr is less than 15,000, for example, it is not possible to reduce the size of the multilayer ceramic capacitor, so that 15,000 or more is considered good. Further, when the dielectric loss tanδ becomes 1.0% or more, for example, the chip of the capacitor For example, it was evaluated that good results were less than 1.0%. On the other hand, if the insulation resistance IR is less than 1.0 × 10 ⁵ MΩ, the multilayer ceramic capacitor does not satisfy the insulation resistance standard, resulting in poor insulation. Therefore, the insulation resistance IR of 1.0 × 10 ⁵ MΩ or more was evaluated as good. .
[0039]
Further, the density was measured by the Archimedes method, and when the density was 5.7 g / cm ³ or less, it was shown that these high dielectric constant dielectric ceramic compositions were insufficiently fired, and the low-temperature firing of less than 1300 ° C. Therefore, a density of 5.7 g / cm ³ or more was evaluated as good. Tables 3 and 4 show the above results.
[0040]
[Table 3]

[0041]
[Table 4]

[0042]
As is clear from Tables 3 and 4, in Sample Nos. 8, 9, 15, 16, 22, 29, 44, and 45, the relative permittivity, which greatly contributes to the reduction in size and capacity of multilayer ceramic capacitors, is 14,000 or less. Sample numbers 8, 16, 29, 39, 45, and 52 all have a firing temperature of 1310 ° C. or higher.
[0043]
Further, Sample Nos. 9, 23, 28, 29 and 38 have a large dielectric loss of 1.15% or more, and Sample Nos. 16, 29, 45 and 52 have firing temperatures as high as 1310 to 1320 ° C. However, the density is as low as less than 5.70 g / cm ³ , resulting in insufficient sintering.
[0044]
Further, the sample numbers 22, 28 and 52 all have low insulation resistance of less than 1.0 × 10 ⁵ .
[0045]
On the other hand, the samples having the sample numbers of the present invention all have a high relative dielectric constant of 15200 or more, a low firing temperature of 1290 ° C. or less, a dielectric loss of 0.93% or less, and a density of 5.72 g / cm ^3. As described above, the insulation resistance is 2.4 × 10 ⁵ MΩ or more, which satisfies all the required characteristics.
[0046]
Next, an internal electrode paste made of silver-palladium (Ag-Pd) powder was placed on each green sheet having a composition shown in Tables 1 and 2 and formed using ceramic slurry prepared in the same manner as above and having a thickness of 10 μm. After the electrodes were screen-printed in a predetermined shape by using, 20 green sheets each having the electrodes printed thereon were laminated, hot-pressed and integrated, and cut into predetermined dimensions to produce green chips.
[0047]
The obtained green chips are held in the air at a temperature of 400 ° C. for 2 hours to completely decompose the binder to remove the binder, and then hold at firing temperatures shown in Tables 3 and 4 corresponding to each composition for 2 hours. And fired.
[0048]
Thereafter, an external extraction electrode made of silver-palladium (Ag-Pd) was baked on the sintered chip to produce a chip capacitor for evaluation.
[0049]
The thickness of one dielectric layer of the chip capacitor for evaluation was 8 μm on average, and the effective electrode area was 1.2 mm ² .
[0050]
Using the evaluation chip capacitor thus obtained, first, under the measurement conditions of a reference temperature of 25 ° C., a frequency of 1.0 kHz, and a measurement voltage of 1.0 Vrms, while measuring the capacitance and the dielectric loss of the evaluation chip capacitor, The temperature change rate of the capacitance at a temperature from −30 ° C. to + 85 ° C. with respect to the capacitance at the reference temperature of 25 ° C. was measured. Further, a high-temperature load test was performed in which a DC voltage of 1.2 × 10 ⁴ V / mm was applied at 85 ° C. This high-temperature load test was performed on 300 chip capacitors for evaluation, and the chip capacitor, which was short-circuited first, was measured by measuring the time from the start of application to the short-circuit.
[0051]
In addition, the measured capacitance of the evaluation chip capacitor with respect to the relative dielectric constant shown in Tables 3 and 4 and the design capacitance calculated from the internal electrode area, the interval between the internal electrodes, the number of layers, and the like of the evaluation chip capacitor after sintering. Was defined as the capacity ratio.
[0052]
Furthermore, five porcelain surfaces of the chip capacitor for evaluation were randomly selected, photographed with a scanning electron microscope at a magnification of 800 times, and 200 crystal grains were randomly selected from these photographs to obtain a section. And the average value was determined to be the average particle size. It was also confirmed whether or not abnormal grain growth had occurred. In this determination of abnormal grain growth, it was determined that abnormal grain growth had occurred when particles having an average particle size of 5 times or more were present.
[0053]
From the above measurement results, it was evaluated that a capacitance value of 200 nF or more was good because a capacitance value of less than 200 nF made it difficult to reduce the size of the multilayer ceramic capacitor.
[0054]
Further, when the dielectric loss is 5.0% or more, it is not practical as a multilayer ceramic capacitor.
[0055]
Further, when the capacity ratio is less than 70%, a sufficient capacity as a multilayer ceramic capacitor cannot be obtained, and miniaturization is difficult.
[0056]
In the high-temperature load test, when a failure occurred within 40 hours, the standard of the multilayer ceramic capacitor was not satisfied. Therefore, it was determined that no failure occurred for 40 hours or more.
[0057]
When the average particle size is 8.0 μm or more, the high-temperature load life of the multilayer ceramic capacitor having a dielectric layer thickness of 10 μm or less does not satisfy the standard. Tables 5 and 6 show these results.
[0058]
[Table 5]

[0059]
[Table 6]

[0060]
As is clear from Tables 5 and 6, the temperature characteristics of Sample No. 1 are out of the standard, and even if the sample conforms to the standard, for example, Sample Nos. 8, 9, 15, 16, 29, 44 and 45 are all electrostatic. Since the capacitance is as small as less than 200 nF, miniaturization of the multilayer ceramic capacitor cannot be realized.
[0061]
Sample numbers 9, 23, 28, 29, and 38 had dielectric losses of 5.2% or more and were out of the practical range.
[0062]
In sample No. 29, abnormal grain growth was observed, and the capacitance ratio was as small as less than 70%.
[0063]
Sample Nos. 29 and 39 have an average particle size of 8.0 μm or more, and the high-temperature load test of the multilayer ceramic capacitor having a single dielectric layer thickness of 10 μm or less does not satisfy the standard.
[0064]
On the other hand, the chip capacitors of the sample numbers of the present invention all have a high capacitance of 211 nF or more, a low firing temperature of 1290 ° C. or less, a small dielectric loss of 4.3% or less, and a capacitance ratio of 84%. % Or more, indicating that no abnormal grain growth was observed at all.
[0065]
【The invention's effect】
As described above, the dielectric porcelain composition of the present invention has a composite oxide composed of barium calcium titanate as a main component, and a rare earth element compound and a zinc compound, a manganese compound, a titanium compound, and a silicon compound as the main components. As a result, it satisfies EIA standard Y5V characteristics, has a relative dielectric constant of 15,000 or more, has a long high-temperature load life, can be fired at a low temperature of less than 1300 ° C, and has a smooth and dense thin plate surface with a thickness of 10 µm or less. Since a simple sheet-shaped sintered body can be obtained, it is possible to obtain a dielectric ceramic composition applicable to various capacitors, including a small-sized and large-capacity multilayer ceramic capacitor using an inexpensive internal electrode material.

Claims (1)

It contains at least Ba, Ca, Ti and Sn as the metal element, the composition formula by molar ratio of the metal element oxide _{(Ba 1-x Ca x)} (Ti 1-y Sn y) O 3
Where x and y are 0.01 ≦ x ≦ 0.10, respectively.
0.04 <y <0.10
A zinc compound is 0.1 to 0.9 parts by weight in terms of ZnO, and a manganese compound is 0.1 to 0.5 parts by weight in terms of MnO ₂ with respect to 100 parts by weight of the main component. 0.1-1.3 parts by weight of a titanium compound in terms of TiO _2, 0.05 to 0.20 parts by weight of silicon compound in terms of SiO _2, a rare earth element compound _{Nd 2 O 3, Sm 2 O} 3, Gd 2 0.8 to 1.8 parts by weight in terms of at least one of O ₃ , La ₂ O ₃ , Pr ₆ O ₁₁ , CeO ₂ , Tb ₄ O ₇ and Eu ₂ O ₃ (however, Bi ₂ O ₃ and Nb ₂ O ₅ are not included) .