WO2015033685A1 - 誘電体磁器組成物およびそれを用いたコンデンサ - Google Patents

誘電体磁器組成物およびそれを用いたコンデンサ Download PDF

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WO2015033685A1
WO2015033685A1 PCT/JP2014/069403 JP2014069403W WO2015033685A1 WO 2015033685 A1 WO2015033685 A1 WO 2015033685A1 JP 2014069403 W JP2014069403 W JP 2014069403W WO 2015033685 A1 WO2015033685 A1 WO 2015033685A1
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dielectric
capacitor
ceramic composition
dielectric constant
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聡史 横溝
祥一郎 鈴木
淳史 本多
信一 檜貝
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株式会社村田製作所
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Definitions

  • the present invention relates to a dielectric ceramic composition and a capacitor using the same, and more particularly to a dielectric ceramic composition used for a dielectric of a capacitor such as a multilayer ceramic capacitor or a single plate ceramic capacitor, and a capacitor using the same.
  • a BaTiO 3 based compound As a main component of the dielectric used in the multilayer ceramic capacitor, a BaTiO 3 based compound is used in order to obtain a high relative dielectric constant.
  • those based on BaTiO 3 having a low Curie temperature (Tc) cannot be used for high temperature applications of 250 ° C. to 450 ° C., for example.
  • a material having a high Tc for example, a system containing (Li, Na, K) NbO 3 as a main component is known as described in JP-A-2009-249244 (Patent Document 1).
  • the dielectric ceramic composition described in Patent Document 1 has a general formula [Na 1 ⁇ x K x ] 1 ⁇ y Li y [Nb 1 ⁇ z Ta z ] O 3 (where x, y, and z are 0 ⁇ x ⁇ 1.0, 0 ⁇ y ⁇ 0.30, 0 ⁇ z ⁇ 0.40) and, as a subcomponent, 1.0 to 8.0 mol% in mol% with respect to the main component Nb 2 O 5 , 1.0 to 8.0 mol% MgO, 3.0 to 16.0 mol% RO (wherein R is at least one of Ca, Sr, and Ba) It is a composition.
  • Patent Document 1 describes a method for producing a dielectric ceramic composition by firing a powder having a similar composition, and a dielectric ceramic capacitor having a dielectric made of the dielectric ceramic composition.
  • the change in the relative permittivity with respect to the temperature change in the vicinity of the tetragonal-orthorhombic phase transition temperature (Tc2) and the Curie temperature (Tc) is significant. It is difficult to use as a capacitor utilizing dielectric properties in a high temperature range of 250 ° C. to 450 ° C. As a place where the capacitor is used in such a high temperature range, for example, the immediate vicinity of a power semiconductor made of gallium nitride can be cited. Gallium nitride can be used up to about 500 ° C., and it is conceivable to use a capacitor in an environment around 300 ° C. constantly assuming its heat resistance.
  • a main object of the present invention is to provide a dielectric ceramic composition having a small change rate of relative permittivity in a high temperature range of 250 ° C. to 450 ° C. with reference to the relative permittivity at 300 ° C., and a capacitor using the same. That is.
  • a dielectric ceramic composition according to the present invention is a dielectric ceramic composition containing Na, Nb, Sn, O, and a perovskite-type compound containing at least one of Ti and Zr as a main component.
  • the Ti content y (mol part) and the Zr content z (mol part) have a relationship of 0.96 ⁇ y + z ⁇ 1.00
  • the content of Nb is
  • the Na content w (mol part) is 1.00 ⁇ w ⁇ 1.10
  • the Sn content ratio x Sn / (Sn + Nb) with respect to the total amount of Sn and Nb is It is a dielectric ceramic composition characterized by 0.05 ⁇ x ⁇ 0.20.
  • condenser concerning this invention is a capacitor
  • the relative permittivity at a high temperature range of 250 ° C. to 450 ° C. increases, and the temperature dependence of the relative permittivity decreases at the high temperature range.
  • the dielectric ceramic composition according to the present invention has a relative dielectric constant of 500 or more at 300 ° C.
  • a dielectric ceramic composition having a small change rate of relative permittivity in a high temperature range of 250 ° C. to 450 ° C. with a relative permittivity at 300 ° C. as a reference, and a capacitor using the same.
  • FIG. 1 is a cross-sectional view showing an example of a single plate ceramic capacitor to which the present invention is applied.
  • a dielectric ceramic composition according to the present invention is a dielectric ceramic composition containing Na, Nb, Sn, O, and a perovskite-type compound containing at least one of Ti and Zr as a main component.
  • the Ti content y (mol part) and the Zr content z (mol part) have a relationship of 0.96 ⁇ y + z ⁇ 1.00
  • the content of Nb is
  • the Na content w (mol part) is 1.00 ⁇ w ⁇ 1.10
  • the Sn content ratio x Sn / (Sn + Nb) with respect to the total amount of Sn and Nb is A dielectric ceramic composition satisfying 0.05 ⁇ x ⁇ 0.20.
  • Circular outer electrodes 14a and 14b made of, for example, Ag are formed on both main surfaces of the dielectric ceramic 12, respectively.
  • the relative dielectric constant in the high temperature range of 250 ° C. to 450 ° C. increases, and the temperature dependence of the specific dielectric constant decreases in the high temperature range, and the relative dielectric constant at 300 ° C.
  • the rate of change of the relative dielectric constant becomes small in a high temperature range of 250 ° C. to 450 ° C. with the rate as a reference.
  • the dielectric ceramic composition of the dielectric ceramic 12 described above has a relative dielectric constant of 500 or more at 300 ° C. Therefore, in the single plate ceramic capacitor 10 using the above-mentioned dielectric ceramic composition, the rate of change of the relative dielectric constant is small in a high temperature range of 250 ° C. to 450 ° C. with the relative dielectric constant at 300 ° C. as a reference.
  • a perovskite compound containing Na, Nb, Sn, O which is a main component of the dielectric ceramic composition of the dielectric ceramic 12, and containing at least one of Ti and Zr, high-purity Na 2
  • the Sn content is 1 mol part
  • the Ti content is y mol part and the Zr content Is the z mole part
  • the Nb content is 1 mole part
  • the Na content is w mole part
  • the Sn content ratio Sn / (Sn + Nb) to the total amount of Sn and Nb is x.
  • this blended powder was wet-mixed with a ball mill and uniformly dispersed, and then subjected to a drying treatment to obtain an adjusted powder.
  • the obtained adjusted powder was calcined at 1000 ° C. to obtain a (Na, Sn) (Nb, Ti, Zr) O 3 main component powder having an average particle size of 0.5 ⁇ m.
  • An appropriate amount of this main component powder was separated and a disk-shaped ceramic molded body was obtained by pressure molding.
  • This ceramic molded body was fired at 1300 ° C. for 2 hours in a reducing atmosphere composed of H 2 —N 2 —H 2 O gas having an oxygen partial pressure of 2.0 ⁇ 10 ⁇ 11 MPa to obtain a disk-shaped sintered body. (Dielectric porcelain 12) was obtained.
  • the external electrodes 14a and 14b are respectively formed by applying an Ag paste on both surfaces of the above-mentioned sintered body and baking at 600 ° C.
  • Each of the single plate ceramic capacitors according to Examples 1 to 16 and Comparative Examples 1 to 21 10 was obtained.
  • the outer dimensions of the single-plate ceramic capacitor 10 thus obtained are 7 to 8 mm in diameter, 0.5 to 0.8 mm in thickness, and the opposing area of the external electrodes 14a and 14b is 38. It was ⁇ 50 mm 2 .
  • the range up to the rate of change of the relative dielectric constant was determined.
  • Table 1 shows ranges of the relative dielectric constant ⁇ r and the relative dielectric constant change rate ⁇ C / C 300 at 300 ° C. for Examples 1 to 16 and Comparative Examples 1 to 21.
  • the graph of FIG. 2 shows the relationship between the temperature T (° C.) and the relative dielectric constant ⁇ r in the single plate ceramic capacitors according to Comparative Example 1, Example 2, and Example 6.
  • the change rate ⁇ C / C 300 of the relative permittivity is within a range of ⁇ 10% in Examples 1 to 16, while ⁇ 10% in Comparative Examples 1 to 21. Is out of range. Further, in Examples 1 to 16, the relative dielectric constant is 500 or more at 300 ° C., and the relative dielectric constant is high at high temperatures.
  • the dielectric ceramic composition according to the present invention is a perovskite type compound containing Nb, Na, Sn, O, and containing at least one of Ti and Zr, and has a high temperature range of 250 ° C. to 450 ° C.
  • the relative permittivity of the film increases, the temperature dependence of the relative permittivity decreases at a high temperature range, and the change rate ⁇ C / C of the relative permittivity at a high temperature range of 250 ° C. to 450 ° C. with the relative permittivity at 300 ° C. 300 is within ⁇ 10%.
  • the relative dielectric constant is 500 or more at 300 ° C., and the relative dielectric constant becomes large at a high temperature range. Therefore, the dielectric ceramic composition according to the present invention is suitably used for the dielectric of the single plate ceramic capacitor 10 taking advantage of such characteristics.
  • the dielectric ceramic composition according to the present invention includes, for example, a rectangular plate-shaped dielectric. It is also used for dielectrics of other capacitors such as single plate ceramic capacitors and multilayer ceramic capacitors.
  • the dielectric ceramic composition according to the present invention is particularly suitably used for a dielectric of a capacitor such as a single plate ceramic capacitor or a multilayer ceramic capacitor.

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Abstract

　３００℃を基準として２５０℃～４５０℃という高温域において比誘電率の温度変化が小さい誘電体磁器組成物を提供する。　単板セラミックコンデンサ１０の誘電体磁器１２として、この発明にかかる誘電体磁器組成物が用いられる。この発明にかかる誘電体磁器組成物は、Ｎａ、Ｎｂ、Ｓｎ、Ｏを含有し、Ｔｉ、Ｚｒの少なくとも一方を含有するペロブスカイト型化合物を主成分とする誘電体磁器組成物であって、Ｓｎの含有量を１モル部としたときに、Ｔｉの含有量ｙ（モル部）とＺｒの含有量ｚ（モル部）が０．９６≦ｙ＋ｚ≦１．００の関係にあり、Ｎｂの含有量を１モル部としたときに、Ｎａの含有量ｗ（モル部）が１．００≦ｗ≦１．１０であり、ＳｎとＮｂとの合計量に対するＳｎの含有比率ｘ＝Ｓｎ／（Ｓｎ＋Ｎｂ）が０．０５≦ｘ≦０．２０である、誘電体磁器組成物である。

Description

誘電体磁器組成物およびそれを用いたコンデンサ
　この発明は、誘電体磁器組成物およびそれを用いたコンデンサに関し、特に、例えば積層セラミックコンデンサや単板セラミックコンデンサなどのコンデンサの誘電体に用いられる誘電体磁器組成物およびそれを用いたコンデンサに関する。
　積層セラミックコンデンサに用いられる誘電体の主成分としては、高い比誘電率を得るために、ＢａＴｉＯ3系の化合物が用いられる。しかしながら、キュリー温度（Ｔｃ）の低いＢａＴｉＯ3を主成分としたものは、例えば２５０℃～４５０℃という高温用途には対応できない。高いＴｃを有する材料としては、例えば特開２００９－２４９２４４公報（特許文献１）に記載されているように、（Ｌｉ，Ｎａ，Ｋ）ＮｂＯ3を主成分とした系が知られている。
　特許文献１に記載されている誘電体磁器組成物は、一般式［Ｎａ1-xＫx］1-yＬｉy［Ｎｂ1-zＴａz］Ｏ3（但し、ｘ、ｙ、ｚは、０≦ｘ≦１．０、０≦ｙ≦０．３０、０≦ｚ≦０．４０）で示される主成分と、副成分として、主成分に対するモル%で１．０～８．０モル%のＮｂ2Ｏ5、１．０～８．０モル%のＭｇＯ、３．０～１６．０モル%のＲＯ（但しＲはＣａ、Ｓｒ、Ｂａの内、少なくとも１種）を含む誘電体磁器組成物である。また、特許文献１には、同様の組成の粉末を焼成することによる誘電体磁器組成物の製造方法およびその誘電体磁器組成物よりなる誘電体を有する誘電体磁器コンデンサが記載されている。
特開２００９－２４９２４４公報
　ところが、特許文献１に記載されている誘電体磁器組成物では、正方晶－斜方晶相転移温度（Ｔｃ２）およびキュリー温度（Ｔｃ）近傍での温度変化に対する比誘電率の変化が激しく、例えば２５０℃～４５０℃という高温域における誘電性を利用したコンデンサとしての利用が困難である。
　このような高温域においてコンデンサが使用される所としては、例えば窒化ガリウムからなるパワー半導体の直近などが挙げられる。窒化ガリウムは５００℃程度までの使用が可能とされており、その耐熱性を前提とした常時３００℃付近の環境でコンデンサを使用することが考えられる。そのようにコンデンサを３００℃付近で使用する場合、周囲の環境によって温度が２５０℃～４５０℃の範囲で変動することが多い。そのため、３００℃における比誘電率を基準として２５０℃～４５０℃という高温域において比誘電率の変化率が小さいコンデンサが望まれる。
　それゆえに、この発明の主たる目的は、３００℃における比誘電率を基準として２５０℃～４５０℃という高温域において比誘電率の変化率が小さい誘電体磁器組成物およびそれを用いたコンデンサを提供することである。
　この発明にかかる誘電体磁器組成物は、Ｎａ、Ｎｂ、Ｓｎ、Ｏを含有し、Ｔｉ、Ｚｒの少なくとも一方を含有するペロブスカイト型化合物を主成分とする誘電体磁器組成物であって、Ｓｎの含有量を１モル部としたときに、Ｔｉの含有量ｙ（モル部）とＺｒの含有量ｚ（モル部）が０．９６≦ｙ＋ｚ≦１．００の関係にあり、Ｎｂの含有量を１モル部としたときに、Ｎａの含有量ｗ（モル部）が１．００≦ｗ≦１．１０であり、ＳｎとＮｂとの合計量に対するＳｎの含有比率ｘ＝Ｓｎ／（Ｓｎ＋Ｎｂ）が０．０５≦ｘ≦０．２０であることを特徴とする、誘電体磁器組成物である。
　この発明にかかるコンデンサは、この発明にかかる誘電体磁器組成物を用いた誘電体を有する、コンデンサである。
　この発明にかかる誘電体磁器組成物では、２５０℃～４５０℃という高温域における比誘電率が大きくなるとともに、高温域において比誘電率の温度依存性が小さくなり、３００℃における比誘電率を基準として２５０℃～４５０℃という高温域において比誘電率の変化率が小さくなる。
　また、この発明にかかる誘電体磁器組成物では、３００℃において比誘電率が５００以上と大きくなる。
　この発明によれば、３００℃における比誘電率を基準として２５０℃～４５０℃という高温域において比誘電率の変化率が小さい誘電体磁器組成物およびそれを用いたコンデンサが得られる。
　この発明の上述の目的、その他の目的、特徴および利点は、図面を参照して行う以下の発明を実施するための形態の説明から一層明らかとなろう。
この発明が適用される単板セラミックコンデンサの一例を示す断面図解図である。 比較例１、実施例２および実施例６にかかる単板セラミックコンデンサにおける温度Ｔ（℃）および比誘電率εｒの関係を示すグラフである。
　図１は、この発明が適用される単板セラミックコンデンサの一例を示す断面図解図である。
　図１に示す単板セラミックコンデンサ１０は、例えば円板状の誘電体磁器１２を含む。誘電体磁器１２としては、この発明にかかる誘電体磁器組成物が用いられ得る。この発明にかかる誘電体磁器組成物は、Ｎａ、Ｎｂ、Ｓｎ、Ｏを含有し、Ｔｉ、Ｚｒの少なくとも一方を含有するペロブスカイト型化合物を主成分とする誘電体磁器組成物であって、Ｓｎの含有量を１モル部としたときに、Ｔｉの含有量ｙ（モル部）とＺｒの含有量ｚ（モル部）が０．９６≦ｙ＋ｚ≦１．００の関係にあり、Ｎｂの含有量を１モル部としたときに、Ｎａの含有量ｗ（モル部）が１．００≦ｗ≦１．１０であり、ＳｎとＮｂとの合計量に対するＳｎの含有比率ｘ＝Ｓｎ／（Ｓｎ＋Ｎｂ）が０．０５≦ｘ≦０．２０である、誘電体磁器組成物である。
　誘電体磁器１２の両主面には、例えばＡｇからなる円形状の外部電極１４ａ、１４ｂがそれぞれ形成される。
　上述の誘電体磁器１２の誘電体磁器組成物では、２５０℃～４５０℃という高温域における比誘電率が大きくなるとともに、高温域において比誘電率の温度依存性が小さくなり、３００℃における比誘電率を基準として２５０℃～４５０℃という高温域において比誘電率の変化率が小さくなる。
　また、上述の誘電体磁器１２の誘電体磁器組成物では、３００℃において比誘電率が５００以上と大きくなる。
　したがって、上述の誘電体磁器組成物が用いられた単板セラミックコンデンサ１０では、３００℃における比誘電率を基準として２５０℃～４５０℃という高温域において比誘電率の変化率が小さくなる。
　次に、実験による実施例１～１６および比較例１～２１にかかる各単板セラミックコンデンサ１０の製造方法の一例について説明する。
　まず、誘電体磁器１２の誘電体磁器組成物の主成分であるＮａ、Ｎｂ、Ｓｎ、Ｏを含有し、Ｔｉ、Ｚｒの少なくとも一方を含有するペロブスカイト型化合物の出発原料として、高純度のＮａ2ＣＯ3、Ｎｂ2Ｏ5、ＳｎＯ、ＴｉＯ2、ＺｒＯ2の各粉末を準備し、これらをＳｎの含有量を１モル部としたときに、Ｔｉの含有量がｙモル部、Ｚｒの含有量がｚモル部、Ｎｂの含有量を１モル部としたときに、Ｎａの含有量がｗモル部、ＳｎとＮｂとの合計量に対するＳｎの含有比率Ｓｎ／（Ｓｎ＋Ｎｂ）がｘとなるように調合した。ここで、実施例１～１６および比較例１～２１におけるｗ、ｘ、ｙ、ｚの値を表１に示す。表１において、後に＊印が付された比較例１～２１は、この発明の範囲外であることを示す。
Figure JPOXMLDOC01-appb-T000001
　次に、この調合粉末をボールミルで湿式混合し、均一に分散させた後、乾燥処理を施して調整粉末を得た。そして、得られた調整粉末を１０００℃で仮焼し、平均粒径が０．５μｍである（Ｎａ，Ｓｎ）（Ｎｂ，Ｔｉ，Ｚｒ）Ｏ3系の主成分粉末を得た。この主成分粉末を適量取り分け、加圧成形により円板状のセラミック成形体を得た。
　このセラミック成形体を酸素分圧２．０×１０-11ＭＰａのＨ2－Ｎ2－Ｈ2Ｏガスからなる還元性雰囲気中において、１３００℃で２時間焼成し、円板状の焼結体（誘電体磁器１２）を得た。
　この焼結体のＸＲＤ構造解析を行ったところ、主成分がニオブ酸ナトリウム系のペロブスカイト型構造を有することが分かった。また、焼結体について、格子体積を比較した結果から、表１の比較例１を除く組成については、Ｓｎが２価として存在していることが確認された。
　次に、上述の焼結体の両面に、Ａｇペーストを塗布し６００℃で焼き付けることによって外部電極１４ａ、１４ｂをそれぞれ形成し、実施例１～１６および比較例１～２１にかかる単板セラミックコンデンサ１０を得た。このようにして得られた単板セラミックコンデンサ１０の外形寸法は、直径が７～８ｍｍであり、厚さが０．５～０．８ｍｍであり、外部電極１４ａ、１４ｂの対向する面積は、３８～５０ｍｍ2であった。
　次に、実施例１～１６および比較例１～２１にかかる単板セラミックコンデンサ１０について、比誘電率に関する温度特性を測定した。この場合、単板セラミックコンデンサ１０の静電容量の温度依存性を、インピーダンスアナライザを用いて、－４０℃～４５０℃の温度範囲において１Ｖｒｍｓ、１ＭＨｚの条件で測定した。得られた測定値より、比誘電率を算出し、比誘電率に関する温度特性を得た。ここでは、３００℃における比誘電率を基準として２５０℃～４５０℃において比誘電率の変化率ΔＣ／Ｃ300の範囲を求めた。この場合、３００℃における比誘電率を基準としたときの２５０℃～４５０℃における最大の比誘電率の変化率から３００℃における比誘電率を基準としたときの２５０℃～４５０℃における最小の比誘電率の変化率までの範囲を求めた。
　実施例１～１６および比較例１～２１について、３００℃における比誘電率εｒおよび比誘電率の変化率ΔＣ／Ｃ300の範囲を表１に示す。
　また、代表として、比較例１、実施例２および実施例６にかかる単板セラミックコンデンサにおける温度Ｔ（℃）および比誘電率εｒの関係を図２のグラフに示す。
　表１および図２のグラフより、比誘電率の変化率ΔＣ／Ｃ300は、実施例１～１６では±１０％の範囲に収まっているのに対して、比較例１～２１では±１０％の範囲を超えている。
　さらに、実施例１～１６では、３００℃において比誘電率が５００以上と高温域において比誘電率が大きい。
　以上のように、この発明にかかる誘電体磁器組成物では、Ｎｂ、Ｎａ、Ｓｎ、Ｏを含有し、Ｔｉ、Ｚｒの少なくとも一方を含有するペロブスカイト型化合物であり、２５０℃～４５０℃という高温域における比誘電率が大きくなるとともに、高温域において比誘電率の温度依存性が小さくなり、３００℃における比誘電率を基準として２５０℃～４５０℃という高温域において比誘電率の変化率ΔＣ／Ｃ300が±１０％に収まっている。
　また、この発明にかかる誘電体磁器組成物では、３００℃において比誘電率が５００以上と高温域において比誘電率が大きくなる。
　したがって、この発明にかかる誘電体磁器組成物は、このような特性を生かして、単板セラミックコンデンサ１０の誘電体に好適に用いられる。
　上述の実施の形態および実施例では、円板状の誘電体を有する単板セラミックコンデンサを例にして説明したが、この発明にかかる誘電体磁器組成物は、例えば４角板状の誘電体を有する単板セラミックコンデンサや積層セラミックコンデンサなど他のコンデンサの誘電体にも用いられる。
　この発明にかかる誘電体磁器組成物は、特に、例えば単板セラミックコンデンサや積層セラミックコンデンサなどのコンデンサの誘電体に好適に用いられる。
　１０　単板セラミックコンデンサ
　１２　誘電体磁器
　１４ａ、１４ｂ　外部電極

Claims (2)

  1. 　Ｎａ、Ｎｂ、Ｓｎ、Ｏを含有し、Ｔｉ、Ｚｒの少なくとも一方を含有するペロブスカイト型化合物を主成分とする誘電体磁器組成物であって、
    　Ｓｎの含有量を１モル部としたときに、Ｔｉの含有量ｙ（モル部）とＺｒの含有量ｚ（モル部）が０．９６≦ｙ＋ｚ≦１．００の関係にあり、
    　Ｎｂの含有量を１モル部としたときに、Ｎａの含有量ｗ（モル部）が１．００≦ｗ≦１．１０であり、
    　ＳｎとＮｂとの合計量に対するＳｎの含有比率ｘ＝Ｓｎ／（Ｓｎ＋Ｎｂ）が０．０５≦ｘ≦０．２０であることを特徴とする、誘電体磁器組成物。
  2. 　請求項１に記載された誘電体磁器組成物を用いた誘電体を有する、コンデンサ。
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005008516A (ja) * 2003-05-29 2005-01-13 Ngk Spark Plug Co Ltd 圧電磁器組成物及びこれを用いた圧電素子
JP2010095404A (ja) * 2008-10-16 2010-04-30 National Institute Of Advanced Industrial Science & Technology 非鉛圧電セラミックス及びこれを用いた圧電・誘電・焦電素子

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005008516A (ja) * 2003-05-29 2005-01-13 Ngk Spark Plug Co Ltd 圧電磁器組成物及びこれを用いた圧電素子
JP2010095404A (ja) * 2008-10-16 2010-04-30 National Institute Of Advanced Industrial Science & Technology 非鉛圧電セラミックス及びこれを用いた圧電・誘電・焦電素子

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