JP2004349484A - Ceramic capacitor for fluorescent lamp ballast and fluorescent lamp ballast - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic capacitor for a fluorescent lamp ballast, prominent in resistance to heat and miniaturized while being small in a loss in high-frequency, and hardly generating heat. <P>SOLUTION: The ceramic capacitor for the fluorescent lamp ballast 2 is provided with a ceramic main body 3 consisting of barium titanate base ceramics and a plurality of external electrodes 4, 5 formed on the outer surface of the ceramic main body 3. The ceramic capacitor for the fluorescent lamp ballast 2 indicates that the tanδ (1KHz) of the barium titanate base ceramics is not higher than 0.30% and the relative permittivity ε of the same ceramics is within 200-700. The fluorescent lamp ballast is provided with the ceramic capacitor for the fluorescent lamp ballast 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００２７】
また、表１に示す、添加成分であるＲ及びＭの原料として、純度９９％以上のＬａ_２Ｏ_３、ＣｅＯ_２、Ｐｒ_６Ｏ_１１、Ｎｄ_２Ｏ_３、Ｓｍ_２Ｏ_３、Ｅｕ_２Ｏ_３、Ｇｄ_２Ｏ_３、Ｔｂ_４Ｏ_７、Ｄｙ_２Ｏ_３、Ｈｏ_２Ｏ_３、Ｅｒ_２Ｏ_３、Ｔｍ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｌｕ_２Ｏ_３及び、ＭｎＯ、ＮｉＯ、ＭｇＯ、Ｆｅ_２Ｏ_３、Ａｌ_２Ｏ_３、Ｃｒ_２Ｏ_３、ＺｎＯを準備した。
【００２８】
また、副成分としての焼結助剤として、Ｂ元素を含有する酸化物の例として０．５５Ｂ_２Ｏ_３−０．２５Ａｌ_２Ｏ_３−０．０３ＭｎＯ−０．１７ＢａＯ（但し、係数はモル比であり、以下、焼結助剤１と称す）、Ｓｉ元素を含有する酸化物の例として０．２５Ｌｉ_２Ｏ−０．６５（０．３０ＴｉＯ_２・０．７０ＳｉＯ_２）−０．１０Ａｌ_２Ｏ_３（但し、係数はモル比であり、以下、焼結助剤２と称す）、Ｓｉ及びＢ元素を含む酸化物の例として０．２５Ｌｉ_２Ｏ−０．３０Ｂ_２Ｏ_３−０．０３ＴｉＯ_２−０．４２ＳｉＯ_２（但し、係数はモル比であり、以下、焼結助剤３と称す）が得られるように、各成分の酸化物、炭酸塩または水酸化物を秤量し、混合粉砕して粉末を得た。この粉末を白金ルツボ中において、１５００℃まで加熱した後、急冷し、粉砕することによって、平均粒径が１μｍ以下のそれぞれの酸化物粉末を得た。また、Ｓｉ元素を含む酸化物のもう１つの例として、酸化珪素をＳｉＯ_２換算で３０重量％含有したコロイドシリカ溶液も準備した。（以下、焼結助剤４と称す）
次に、表１に示す組成物が得られるように、以上のように準備したチタン酸バリウム系固溶体、添加成分用原料及び副成分としての焼結助剤を秤量した。なお、添加成分Ｒ（但し、ＲはＬａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ及びＬｕから選ばれる少なくとも１種の金属元素の酸化物）の係数ａは、それぞれの酸化物を金属元素が１元素含まれる化学式に換算したときのモル比を示す。また、添加成分Ｍ（但し、ＭはＭｎ，Ｎｉ，Ｍｇ，Ｆｅ，Ａｌ，Ｃｒ及びＺｎから選ばれる少なくとも１種の金属元素の酸化物）の係数ｂは、それぞれの酸化物を金属元素が１元素含まれる化学式に換算したときのモル比を示す。また、焼結助剤の含有量は、主成分［［（Ｂａ_{１−ｘ−ｙ}Ｓｒ_ｘＣａ_ｙ）Ｏ］_ｍＴｉＯ_２＋ａＲ＋ｂＭ］１００重量部に対する含有部数である。
【００２９】
次に、この秤量物にポリビニルブチラール系バインダー及びエタノールなどの有機溶剤を加えて、ボールミルにより湿式混合し、スラリーを調製した。このスラリーをドクターブレード法によりシート成形し、厚み２５μｍの矩形のグリーンシートを得た。
【００３０】
次に、このグリーンシート上に、Ｎｉを主成分とする導電ペーストを印刷し、内部電極を構成するための導電ペースト層を形成した。その後、導電ペースト層が形成されたグリーンシートを、導電ペースト層が引き出されている側が互い違いとなるように複数枚積層し、積層体を得た。この積層体を、Ｎ_２雰囲気中にて３５０℃の温度に加熱し、バインダーを除去した後、酸素分圧１０^−９〜１０^−１２ＭＰａのＨ_２−Ｎ_２−Ｈ_２Ｏガスからなる還元性雰囲気中において表２に示す温度で２時間焼成し、セラミック焼結体を得た。
【００３１】
その後、得られたセラミック焼結体の両端面にＢ_２Ｏ_３−Ｌｉ_２Ｏ−ＳｉＯ_２−ＢａＯ系のガラスフリットを含有するＡｇペーストを塗布し、Ｎ_２雰囲気中において６００℃の温度で焼付け、内部電極と電気的に接続された外部電極を形成した。
【００３２】
次に、硫酸ニッケル及び塩化ニッケル、ホウ酸からなるニッケルめっき液を用意し、バレルめっき法にてＡｇ外部電極上にニッケルめっきした。最後に、ＡＳ浴（アルカノールスルホン酸）からなるはんだめっき液を用意し、バレルめっき法にて、このニッケルめっき被膜上にはんだめっきして、外部電極上にめっき被膜された積層セラミックコンデンサを得た。
【００３３】
このようにして得た積層セラミックコンデンサの外形寸法は、幅３．２ｍｍ、長さ４．５ｍｍ、厚さ１．０ｍｍであり、内部電極間に介在する誘電体セラミック層の厚みは２０μｍであった。また、有効誘電体セラミック層の総数は１０であり、一層当たりの対向電極の面積は８．８×１０^−６ｍ^２であった。
【００３４】
次に、以上得られた積層セラミックコンデンサについて、電気的特性を測定した。静電容量（Ｃ）及び誘電損失（ｔａｎδ）は自動ブリッジ式測定器を用いて、周波数１ＫＨｚ、１Ｖｒｍｓ、温度２５℃にて測定し、静電容量から誘電率（ε）を算出した。次に、絶縁抵抗（ＩＲ）を測定するために、絶縁抵抗計を用い、２００Ｖの直流電圧を２分間印加して２５℃での絶縁抵抗（ＩＲ）を測定し、静電容量（Ｃ）と絶縁抵抗（ＩＲ）との積、すなわちＣＲ積を求めた。
【００３５】
また、温度変化に対する静電容量の変化率を測定した。温度変化に対する静電容量の変化率については、２０℃での静電容量を基準とした、−２５℃〜２０℃間での静電容量の最大変化率（−２５℃（％））と、２０℃〜８５℃間での静電容量の最大変化率（８５℃（％））を求めた（ΔＣ／Ｃ２０）。また、２５℃での静電容量を基準とした、−５５℃〜２５℃間での静電容量の最大変化率（−５５℃（％））と、２５℃〜１２５℃間での静電容量の最大変化率（１２５℃（％））を求めた（ΔＣ／Ｃ２５）。
【００３６】
また、高温負荷試験として、各試料を３６個づつ、温度１５０℃にて直流電圧を５００Ｖ印加して、その絶縁抵抗の経時変化を測定した。なお、高温負荷寿命試験は各試料の絶縁抵抗値（ＩＲ）が１０^６Ω以下になったときの時間を寿命時間とし、その平均寿命時間を求めた。
【００３７】
これらの結果を表２に示す。なお、表２において、試料番号に＊印を付したものは、本発明の範囲外のものであり、その他は本発明の範囲内のものである。
【００３８】
【表２】

【００３９】
表１、２の試料番号１、５〜１８から明らかなように、内部電極にＮｉなどの卑金属を用いることができ、誘電率が２００以上であって、１ＫＨｚ、１Ｖｒｍｓの条件下での誘電損失（ｔａｎδ）が０．３０％以下と小さくて発熱が抑えられた、高周波・高電圧交流下での特性に優れた積層セラミックコンデンサが得られる。さらに、試料番号１、７〜１８のように、焼結助剤の含有量を限定することにより、１３５０℃以下で焼結が可能であり、静電容量の温度特性がＪＩＳ規格で規定するＢ特性及びＥＩＡ規格で規定するＸ７Ｒ特性を満足する。さらにまた、試料番号７〜１８のように、チタン酸バリウム系固溶体を［（Ｂａ_{１−ｘ−ｙ}Ｓｒ_ｘＣａ_ｙ）Ｏ］_ｍＴｉＯ_２と表わしたときのｘ＋ｙの値を限定することにより、１０ｋＶ／ｍｍの電界強度下での絶縁抵抗が静電容量との積（ＣＲ積）で表わした場合に、室温で７００Ω・Ｆ以下と高い値を示す。また、１５０℃、ＤＣ２５ｋＶ／ｍｍ印加の高温負荷試験において、平均寿命時間が７００時間以上と長い。
【００４０】
試料番号２のように、Ｒの含有量ａが０．１２以下の場合には、１ＫＨｚ、１Ｖｒｍｓでのｔａｎδが０．３０％を越えて大きくなり、発熱が大きくなるので好ましくない。一方、試料番号３のようにＲの含有量ａが０．３０を越える場合には、焼結性が低下し、焼成温度が１３５０℃を越える。また、誘電率も小さくなり、２００未満となるので好ましくない。
【００４１】
試料番号４のように、ｍが１．０５０を越える場合、焼結不足となり好ましくない。
表２から明らかなように、試料番号１、５〜１８から積層セラミックコンデンサでは、比誘電率εが２００以上と高く、かつｔａｎδ（１ＫＨｚ）が０．３０％以下であることがわかる。
【００４２】
（実施例２）
次に、実施例１で得られたｔａｎδ（１ＫＨｚ）が０．３０％以下であり、比誘電率εが２００以上であるチタン酸バリウム系セラミックスを用いた積層セラミックコンデンサが蛍光灯安定器用セラミックコンデンサとして適していることを示す実験例を説明する。
【００４３】
実施例１の試料番号１６と同じセラミックス組成の積層セラミックコンデンサを、図１に示した蛍光灯安定器用セラミックコンデンサ２として用いた。なお、積層セラミックコンデンサの寸法は、長さ３．２ｍｍ、幅１．６ｍｍ×厚み１．６ｍｍとし、設計静電容量は６８００ｐＦとした。比較のために、従来より蛍光灯安定器用コンデンサとして用いられているフィルムコンデンサを用意した。このフィルムコンデンサの静電容量と６８００ｐＦであり、寸法は長さ１１．０ｍｍ×幅１３．９ｍｍ×厚み４．７ｍｍである。
【００４４】
上記積層セラミックコンデンサ及び比較例のフィルムコンデンサの最高保証温度は、下記の表３に示す通り、それぞれ、１５０℃及び１０５〜１２５℃である。従って、比較例のフィルムコンデンサに比べて、本実施例のセラミックコンデンサを用いることにより、耐熱性を高め得ることがわかる。
【００４５】
また、高温負荷試験として、セラミックコンデンサとフィルムコンデンサを１０個ずつ、温度１５０℃にて直流電圧５５０Ｖ印加して、その絶縁抵抗の経時変化を測定した。なお、高温負荷寿命試験は各コンデンサの絶縁抵抗値（ＩＲ）が１０^６Ω以下になったときの時間を寿命時間とし、その平均寿命時間を求めた。その結果、表３に示す通り、フィルムコンデンサが７４時間であるのに対して、セラミックコンデンサは７８９時間と長い。
【００４６】
また、積層セラミックコンデンサでは、比較例のフィルムコンデンサに比べて寸法が同じ静電容量を得る場合、小型とすることができるため、コンデンサ自体の小型化、並びにコンデンサの取り付け位置の制限が少なくなるため、蛍光灯安定器の小型化が容易となる。
【００４７】
さらに、下記の表３に示すように、高周波（５０〜１００ＫＨｚ）での損失が、従来の高誘電率系セラミック材料に比べて非常に小さく、従って、高周波損失が小さいため、蛍光灯の安定器に用いた場合の発熱が生じ難いことがわかる。
【００４８】
さらに、実施例の積層セラミックコンデンサでは、還元雰囲気下で焼結が可能であるため、内部電極材料としてＮｉなどの卑金属を使用することができ、従って、コストを低減し得ることがわかる。加えて、環境負荷物質となるＰｂなどを含有していないため、耐環境性に優れた蛍光灯安定器用セラミックコンデンサを構成し得ることがわかる。
【００４９】
【表３】

【００５０】
【発明の効果】
本発明に係る蛍光灯安定器用セラミックコンデンサでは、セラミック本体を構成するチタン酸バリウム系セラミックスのｔａｎδ（１ＫＨｚ）が０．３０％以下であり、比誘電率εが２００〜７００の範囲にあるため、蛍光灯安定器用セラミックコンデンサとして用いた場合、高周波損失が小さく、発熱が生じ難い。また、同じ静電容量を得る場合、従来のフィルムコンデンサに比べて小型化を図ることができる。従って、コンデンサ自体の小型化、並びに蛍光灯安定器におけるコンデンサ取り付け位置の自由度が高まることにより、蛍光灯安定器の小型化を容易に図ることができる。
【００５１】
さらに、チタン酸バリウム系セラミックスによりセラミック本体が構成されているので、蛍光灯安定器用セラミックコンデンサの耐熱性も高めることができる。
【００５２】
従って、本発明に係る蛍光灯安定器用セラミックコンデンサを備えた本発明の蛍光灯用安定器では、耐熱性の向上及び小型化を図ることができる。
【図面の簡単な説明】
【図１】本発明の一実施例の蛍光灯安定器用セラミックコンデンサが備えられた蛍光灯安定器を蛍光灯に接続した状態を示す概略構成図。
【図２】本発明の一実施例で用意される蛍光灯安定器用セラミックコンデンサの一例を説明するための正面断面図。
【符号の説明】
１…蛍光灯
２…蛍光灯安定器用セラミックコンデンサ
３…セラミック本体
４，５…外部電極
６ａ〜６ｄ…内部電極
Ｌ…インダクタンス[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a ceramic capacitor used for a fluorescent lamp ballast and a fluorescent lamp ballast.
[0002]
[Prior art]
Conventionally, a film capacitor has been usually used as a capacitor for constituting a ballast of a fluorescent lamp. Since the temperature of the ballast of a fluorescent lamp becomes considerably high, the heat resistance of a film capacitor is not always sufficient. Further, the size of the film capacitor must be large, and the mounting position in the circuit of the ballast is restricted. Also, it was difficult to reduce the size of the ballast.
[0003]
On the other hand, it is known to reduce the size and weight by replacing the film capacitor or the like with a ceramic capacitor as a power supply smoothing capacitor of the discharge lamp lighting device (for example, see Patent Document 1).
[0004]
Therefore, it is conceivable to use a ceramic capacitor as a capacitor of the ballast for a fluorescent lamp.
[0005]
[Patent Document 1]
JP-A-62-52916
[Problems to be solved by the invention]
Since the capacitor of the fluorescent lamp ballast is a capacitor that passes an electric current to heat the target when the arc tube is turned on, it is used at a high temperature and requires heat resistance.
[0007]
Therefore, it is conceivable to use a ceramic capacitor made of a ceramic material for temperature compensation having good heat resistance as a capacitor of a ballast for a fluorescent lamp. However, since the relative dielectric constant ε is as low as about 70, when the ceramic material for temperature compensation is used, the dimensions of the capacitor are almost the same as those of the above-described film capacitor, and it is also difficult to reduce the size.
[0008]
On the other hand, ceramics having a high dielectric constant are known as ceramic materials constituting a multilayer ceramic capacitor. By using such a ceramic having a high dielectric constant, for example, the size of the capacitor of the ballast for a fluorescent lamp can be reduced in size. However, a conventional multilayer ceramic capacitor using a ceramic material having a high dielectric constant has a problem that high-frequency loss is large and heat generation is large.
[0009]
An object of the present invention is to solve the above-mentioned disadvantages of the prior art, to provide excellent heat resistance, to reduce loss at high frequencies of about 50 to 100 KHz, to have a high relative dielectric constant, and to reduce the size of a fluorescent lamp ballast. It is an object of the present invention to provide a fluorescent lamp ballast ceramic capacitor which can be achieved, and a fluorescent lamp ballast using the ceramic capacitor.
[0010]
[Means for Solving the Problems]
A ceramic capacitor for a fluorescent lamp ballast according to the present invention includes a ceramic body made of a barium titanate-based ceramic, and a plurality of external electrodes formed on an outer surface of the ceramic body, and a tanδ (1 KHz) of the barium titanate-based ceramic is provided. Is 0.30% or less, and the relative dielectric constant ε is in the range of 200 to 700.
[0011]
The barium titanate-based ceramic preferably has a barium titanate-based solid solution and additional components, and has a general formula of ABO ₃ + aR + bM (where ABO ₃ is a barium titanate-based solid solution represented by a general formula showing a perovskite structure). R is an oxide of at least one metal element selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and M is Mn, Ni , Mg, Fe, Al, Cr and Zn are oxides of at least one metal element, and a and b represent the molar ratio of each oxide when converted to a chemical formula containing one metal element. )
0.950 ≦ A / B (molar ratio) ≦ 1.050
0.12 <a ≦ 0.30
0.04 ≦ b ≦ 0.30
The one containing a sintering aid as an auxiliary component with respect to the main component in the range is used. The barium titanate-based ceramics having such a composition has a tan δ (1 KHz) of 0.30% or less, therefore has a small high-frequency loss, and does not easily generate heat when used in a fluorescent lamp stabilizer. In addition, since the relative dielectric constant ε is in the range of 200 to 700, the size can be reduced. Further, since the ceramic body is made of the barium titanate-based ceramic, the heat resistance of the ceramic capacitor is also good.
[0012]
Further, when the barium titanate-based ceramics is used, a base metal such as Ni can be used as an internal electrode material, whereby the cost of the ceramic capacitor for a fluorescent lamp stabilizer can be reduced.
[0013]
Preferably, 0.8 to 8.0 parts by weight of the sintering aid is added to 100 parts by weight of the main component.
In a specific aspect of the ceramic capacitor for a fluorescent lamp ballast according to the present invention, a plurality of internal electrodes are formed in the ceramic body, thereby providing a multilayer-type fluorescent lamp ballast ceramic capacitor according to the present invention. Therefore, it is possible to provide an even smaller ceramic capacitor for a fluorescent lamp ballast.
[0014]
The ballast for a fluorescent lamp according to the present invention includes a ceramic capacitor configured according to the present invention. As described above, the fluorescent lamp ballast ceramic capacitor according to the present invention has excellent heat resistance, can be reduced in size, and has a small high-frequency loss. Can be reduced in size and the reliability can be improved.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be clarified by describing specific examples of the present invention.
[0016]
FIG. 1 is a diagram schematically showing a circuit configuration in which a fluorescent lamp ballast according to the present invention is connected to a fluorescent lamp. In FIG. 1, a ballast having an inductance L and a fluorescent lamp ballast capacitor 2 is connected to a fluorescent lamp 1. In this circuit, a voltage load of about 70 KHz and 750 Vp _-p is applied to the fluorescent lamp ballast capacitor 2 at the time of preheating lighting of the fluorescent lamp 1 and about 60 KHz and 250 vp _-p at the time of steady lighting for an input of 100 V AC.
[0017]
In this embodiment, a ceramic capacitor schematically shown in FIG. 2 is used as the fluorescent lamp ballast capacitor 2. That is, the ceramic capacitor 2 for a fluorescent lamp ballast shown in FIG. 2 includes a ceramic body 3 made of barium titanate-based ceramics, and external electrodes 4 and 5 formed on end faces 3 a and 3 b of the ceramic body 3. In the ceramic body 3, a plurality of internal electrodes 6a to 6d are arranged so as to overlap with each other via a ceramic layer.
[0018]
The tan δ (1 KHz) of the barium titanate-based ceramics constituting the fluorescent lamp ballast ceramic capacitor 2 is 0.30% or less, and the relative dielectric constant ε is in the range of 200 to 700.
[0019]
That is, since the tan δ (1 KHz) of the barium titanate-based ceramics is 0.30% or less, the high-frequency loss is small, and heat is generated when the fluorescent lamp ballast ceramic capacitor 2 is used as a capacitor constituting the ballast of the fluorescent lamp 1. The amount can be reduced. Further, since the relative dielectric constant ε is 200 or more, the size of the ceramic capacitor 2 for a fluorescent lamp stabilizer can be reduced. In particular, in this embodiment, since the ceramic capacitor 2 for a fluorescent lamp ballast is a multilayer ceramic capacitor, it is possible to obtain a large capacitance with the same size as a single-plate ceramic capacitor. Further miniaturization of the ceramic capacitor 2 for a ballast has been achieved.
[0020]
However, the ceramic capacitor for a fluorescent lamp ballast according to the present invention may be a single-plate ceramic capacitor having no internal electrode.
If the relative dielectric constant ε exceeds 700, cracks occur in the ceramic due to the electrostriction phenomenon, which is inappropriate.
[0021]
The ceramic constituting the ceramic body is not particularly limited as long as it has a tan δ (1 KHz) of 0.30% or less and a relative dielectric constant ε in a range of 200 to 700, but preferably has a high dielectric constant described below. Of barium titanate-based ceramics.
[0022]
This barium titanate-based ceramic has a barium titanate-based solid solution and additional components, and has a general formula of ABO ₃ + aR + bM (where ABO ₃ is a barium titanate-based solid solution represented by a general formula showing a perovskite structure; Is an oxide of at least one metal element selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; M is Mn, Ni, Mg, Fe , Al, Cr, and Zn are oxides of at least one metal element, and a and b represent the molar ratios of the respective oxides when converted to a chemical formula containing one metal element). When
0.950 ≦ A / B (molar ratio) ≦ 1.050
0.12 <a ≦ 0.30
0.04 ≦ b ≦ 0.30
The sintering aid is contained as a sub-component with respect to the main component in the range.
[0023]
The above barium titanate-based ceramics is characterized in that the firing temperature is 1350 ° C. or less, the relative dielectric constant ε is 200 or more, and the loss and heat generation under high frequency and high voltage AC are small. More specifically, the loss under the conditions of 1 KHz and 1 Vrms is 0.30% or less.
[0024]
In addition, as the additive component in the barium titanate-based ceramic, preferably, X (Zr, Hf) O ₃ (where X is at least one metal element selected from Ba, Sr, and Ca) and D (where , And D contain at least one of oxides of at least one metal element selected from V, Nb, Ta, Mo, W, Y, and Sc), whereby the characteristics can be improved. Next, the characteristics of the barium titanate-based ceramics will be described based on specific experimental examples.
[0025]
(Example 1)
First, BaCO ₃ , CaCO ₃ , SrCO ₃ , and TiO ₂ were prepared as starting materials. These materials, of the compositions shown in Table 1, which is one of barium titanate-based solid solution represented by the general formula ABO ₃ showing the perovskite structure _{[(Ba 1-x-y} Sr x Ca y) O ] it was weighed such that the composition of the _m TiO ₂ is obtained. Thereafter, these weighed raw materials were wet-mixed with a ball mill, pulverized, dried, and calcined in air at 1120 ° C. for 2 hours to obtain a barium titanate-based solid solution.
[0026]
[Table 1]

[0027]
Further, as raw materials for R and M, which are additive components, shown in Table 1, La ₂ O ₃ , CeO ₂ , Pr ₆ O ₁₁ , Nd ₂ O ₃ , Sm ₂ O ₃ , and Eu ₂ O ₃ having a purity of 99% or more. _{, Gd 2 O 3, Tb 4} O 7, Dy 2 O 3, Ho 2 O 3, Er 2 O 3, Tm 2 O 3, Yb 2 O 3, Lu 2 O 3 and, MnO, NiO, MgO, Fe 2 O ₃ , Al ₂ O ₃ , Cr ₂ O ₃ , and ZnO were prepared.
[0028]
Further, as a sintering agent as a secondary component, 0.55B ₂ O ₃ -0.25Al Examples of oxide containing B element ₂ O ₃ -0.03MnO-0.17BaO (where coefficient molar ratio And hereinafter referred to as sintering aid 1), and as an example of an oxide containing a Si element, 0.25Li ₂ O-0.65 (0.30TiO ₂ .0.70SiO ₂ ) -0.10Al ₂ O ₃ (where the coefficient is the molar ratio, hereinafter referred to as sintering aid _{2), 0.25Li 2 O-0.30B} 2 O 3 -0.03TiO 2 as an example of an oxide containing Si and B elements -0.42SiO 2 _(where the coefficient is the molar ratio, hereinafter referred to as sintering aids. 3) so that the obtained oxide of each component, and weighed carbonate or hydroxide, mixed and ground Powder was obtained. This powder was heated to 1500 ° C. in a platinum crucible, quenched, and pulverized to obtain each oxide powder having an average particle diameter of 1 μm or less. Further, as another example of the oxide containing the Si element, a colloidal silica solution containing 30% by weight of silicon oxide in terms of SiO ₂ was also prepared. (Hereinafter referred to as sintering aid 4)
Next, the barium titanate-based solid solution prepared as described above, a raw material for an additive component, and a sintering aid as an auxiliary component were weighed so that the composition shown in Table 1 was obtained. The additive component R (where R is an oxide of at least one metal element selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) Indicates a molar ratio when each oxide is converted into a chemical formula containing one metal element. The coefficient b of the additive component M (where M is an oxide of at least one metal element selected from Mn, Ni, Mg, Fe, Al, Cr and Zn) is such that each of the oxides is 1 metal element. It shows the molar ratio when converted to the chemical formula containing the element. The content of the sintering aid is contained copies relative to the main component _{[[(Ba 1-x-} y Sr x Ca y) O] m TiO 2 + aR + bM] 100 parts by weight.
[0029]
Next, an organic solvent such as a polyvinyl butyral-based binder and ethanol was added to the weighed material, and the mixture was wet-mixed with a ball mill to prepare a slurry. This slurry was formed into a sheet by a doctor blade method to obtain a rectangular green sheet having a thickness of 25 μm.
[0030]
Next, a conductive paste containing Ni as a main component was printed on the green sheet to form a conductive paste layer for forming internal electrodes. Thereafter, a plurality of green sheets on which the conductive paste layer was formed were stacked such that the side from which the conductive paste layer was drawn out was alternated to obtain a laminate. This laminate is heated to a temperature of 350 ° C. in an N ₂ atmosphere to remove the binder, and then reduced with an H ₂ —N ₂ —H ₂ O gas having an oxygen partial pressure of 10 ⁻⁹ to 10 ⁻¹² MPa. It was fired at a temperature shown in Table 2 for 2 hours in a neutral atmosphere to obtain a ceramic sintered body.
[0031]
Thereafter, an Ag paste containing a glass frit of B ₂ O ₃ —Li ₂ O—SiO ₂ —BaO system is applied to both end surfaces of the obtained ceramic sintered body, and baked at a temperature of 600 ° C. in an N ₂ atmosphere. Then, an external electrode electrically connected to the internal electrode was formed.
[0032]
Next, a nickel plating solution comprising nickel sulfate, nickel chloride, and boric acid was prepared, and nickel plating was performed on the Ag external electrode by barrel plating. Finally, a solder plating solution composed of an AS bath (alkanol sulfonic acid) was prepared, and solder plating was performed on the nickel plating film by barrel plating to obtain a multilayer ceramic capacitor having a plating film on external electrodes. .
[0033]
The external dimensions of the multilayer ceramic capacitor thus obtained were 3.2 mm in width, 4.5 mm in length, and 1.0 mm in thickness, and the thickness of the dielectric ceramic layer interposed between the internal electrodes was 20 μm. . The total number of effective dielectric ceramic layers was 10, and the area of the counter electrode per layer was 8.8 × 10 ⁻⁶ m ² .
[0034]
Next, the electrical characteristics of the obtained multilayer ceramic capacitor were measured. The capacitance (C) and the dielectric loss (tan δ) were measured at a frequency of 1 KHz, 1 Vrms and a temperature of 25 ° C. using an automatic bridge type measuring instrument, and the dielectric constant (ε) was calculated from the capacitance. Next, in order to measure the insulation resistance (IR), a DC voltage of 200 V was applied for 2 minutes using an insulation resistance meter, and the insulation resistance (IR) at 25 ° C. was measured. The product with the insulation resistance (IR), that is, the CR product was determined.
[0035]
Further, the rate of change of the capacitance with respect to the temperature change was measured. Regarding the rate of change of the capacitance with respect to temperature change, the maximum rate of change of the capacitance between −25 ° C. and 20 ° C. (−25 ° C. (%)) based on the capacitance at 20 ° C., The maximum rate of change of capacitance (85 ° C. (%)) between 20 ° C. and 85 ° C. was determined (ΔC / C20). The maximum rate of change of the capacitance between -55 ° C and 25 ° C (-55 ° C (%)) based on the capacitance at 25 ° C and the capacitance between 25 ° C and 125 ° C The maximum change rate of the capacity (125 ° C. (%)) was determined (ΔC / C25).
[0036]
In addition, as a high-temperature load test, a DC voltage of 500 V was applied at a temperature of 150 ° C. for each of 36 samples, and the change with time of the insulation resistance was measured. In the high-temperature load life test, the time when the insulation resistance value (IR) of each sample became 10 ⁶ Ω or less was defined as the life time, and the average life time was determined.
[0037]
Table 2 shows the results. In Table 2, those marked with an asterisk (*) are out of the scope of the present invention, and the others are within the scope of the present invention.
[0038]
[Table 2]

[0039]
As is clear from Sample Nos. 1 to 5 to 18 in Tables 1 and 2, a base metal such as Ni can be used for the internal electrode, the dielectric constant is 200 or more, and the dielectric loss under the conditions of 1 KHz and 1 Vrms. A multilayer ceramic capacitor having a small (tan δ) of 0.30% or less and suppressing heat generation and having excellent characteristics under high frequency and high voltage AC can be obtained. Further, by limiting the content of the sintering aid as in Sample Nos. 1 and 7 to 18, sintering can be performed at 1350 ° C. or less, and the temperature characteristic of the capacitance is defined by B defined by JIS standards. It satisfies the characteristics and the X7R characteristics specified in the EIA standard. Furthermore, as in sample No. 7-18, by limiting the value of x + y when represents a barium titanate-based solid solution and _{[(Ba 1-x-y} Sr x Ca y) O] m TiO 2, When the insulation resistance under an electric field strength of 10 kV / mm is represented by a product (CR product) with the capacitance, it shows a high value of 700Ω · F or less at room temperature. In a high-temperature load test at 150 ° C. and a DC voltage of 25 kV / mm, the average life time is as long as 700 hours or more.
[0040]
When the content a of R is 0.12 or less as in Sample No. 2, tan δ at 1 KHz and 1 Vrms exceeds 0.30%, which is not preferable because heat generation increases. On the other hand, when the R content a exceeds 0.30 as in Sample No. 3, the sinterability decreases, and the firing temperature exceeds 1350 ° C. In addition, the dielectric constant becomes small and becomes less than 200, which is not preferable.
[0041]
When m exceeds 1.050 as in sample No. 4, sintering becomes insufficient, which is not preferable.
As is clear from Table 2, it can be seen from Sample Nos. 1 to 5 to 18 that the multilayer ceramic capacitor has a high relative dielectric constant ε of 200 or more and a tan δ (1 KHz) of 0.30% or less.
[0042]
(Example 2)
Next, a multilayer ceramic capacitor using a barium titanate-based ceramic having a tan δ (1 KHz) of 0.30% or less and a relative dielectric constant ε of 200 or more obtained in Example 1 is a ceramic capacitor for a fluorescent lamp stabilizer. An experimental example showing that the method is suitable for will be described.
[0043]
A multilayer ceramic capacitor having the same ceramic composition as Sample No. 16 of Example 1 was used as the ceramic capacitor 2 for a fluorescent lamp ballast shown in FIG. The dimensions of the multilayer ceramic capacitor were 3.2 mm in length, 1.6 mm in width × 1.6 mm in thickness, and the design capacitance was 6800 pF. For comparison, a film capacitor conventionally used as a fluorescent lamp ballast capacitor was prepared. The capacitance of this film capacitor is 6800 pF, and the dimensions are 11.0 mm long × 13.9 mm wide × 4.7 mm thick.
[0044]
The maximum guaranteed temperatures of the multilayer ceramic capacitor and the film capacitor of the comparative example are 150 ° C. and 105 ° C. to 125 ° C., respectively, as shown in Table 3 below. Therefore, it can be seen that the use of the ceramic capacitor of this example can improve the heat resistance as compared with the film capacitor of the comparative example.
[0045]
As a high-temperature load test, 10 ceramic capacitors and 10 film capacitors were applied at a temperature of 150 ° C. and a DC voltage of 550 V was applied, and changes with time of the insulation resistance were measured. In the high-temperature load life test, the time when the insulation resistance value (IR) of each capacitor became 10 ⁶ Ω or less was defined as the life time, and the average life time was determined. As a result, as shown in Table 3, the film capacitor is 74 hours, whereas the ceramic capacitor is 789 hours.
[0046]
Further, in the case of obtaining the same capacitance as the film capacitor of the comparative example, the multilayer ceramic capacitor can be reduced in size, so that the size of the capacitor itself is reduced and the limitation on the mounting position of the capacitor is reduced. In addition, downsizing of the fluorescent lamp ballast becomes easy.
[0047]
Further, as shown in Table 3 below, the loss at a high frequency (50 to 100 KHz) is much smaller than that of a conventional high dielectric constant ceramic material, and thus the loss at a high frequency is small. It can be seen that heat is hardly generated in the case of the use in Example 1.
[0048]
Furthermore, in the multilayer ceramic capacitor of the embodiment, since sintering is possible in a reducing atmosphere, it is found that a base metal such as Ni can be used as an internal electrode material, and thus the cost can be reduced. In addition, since it does not contain Pb or the like as an environmentally harmful substance, it can be seen that a ceramic capacitor for a fluorescent lamp ballast having excellent environmental resistance can be formed.
[0049]
[Table 3]

[0050]
【The invention's effect】
In the ceramic capacitor for a fluorescent lamp ballast according to the present invention, the tan δ (1 KHz) of the barium titanate-based ceramic constituting the ceramic main body is 0.30% or less and the relative dielectric constant ε is in the range of 200 to 700. When used as a ceramic capacitor for a fluorescent lamp ballast, high-frequency loss is small and heat is hardly generated. Further, when the same capacitance is obtained, the size can be reduced as compared with a conventional film capacitor. Accordingly, the size of the condenser itself can be reduced, and the degree of freedom of the mounting position of the condenser in the fluorescent lamp ballast can be increased, so that the fluorescent lamp ballast can be easily downsized.
[0051]
Further, since the ceramic main body is made of barium titanate-based ceramic, the heat resistance of the ceramic capacitor for a fluorescent lamp stabilizer can be increased.
[0052]
Therefore, in the fluorescent lamp ballast of the present invention provided with the fluorescent lamp ballast ceramic capacitor according to the present invention, the heat resistance can be improved and the size can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a state in which a fluorescent lamp ballast provided with a fluorescent lamp ballast ceramic capacitor according to an embodiment of the present invention is connected to a fluorescent lamp.
FIG. 2 is a front sectional view for explaining an example of a ceramic capacitor for a fluorescent lamp stabilizer prepared in one embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fluorescent lamp 2 ... Ceramic capacitor for fluorescent lamp stabilizers 3 ... Ceramic bodies 4, 5 ... External electrodes 6a-6d ... Internal electrodes L ... Inductance

Claims (5)

A ceramic body made of barium titanate-based ceramics,
A plurality of external electrodes formed on the outer surface of the ceramic body,
A tan δ (1 KHz) of the barium titanate-based ceramic is 0.30% or less, and a relative dielectric constant ε is in a range of 200 to 700. A ceramic capacitor for a fluorescent lamp ballast. The ceramic body made of the barium titanate-based ceramic has a barium titanate-based solid solution and an additional component, and has a general formula of ABO ₃ + aR + bM (where ABO ₃ is a barium titanate-based solid solution represented by a general formula showing a perovskite structure. R is an oxide of at least one metal element selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and M is Mn, Ni , Mg, Fe, Al, Cr and Zn are oxides of at least one metal element, and a and b represent the molar ratio of each oxide when converted to a chemical formula containing one metal element. )
0.950 ≦ A / B (molar ratio) ≦ 1.050
0.12 <a ≦ 0.30
0.04 ≦ b ≦ 0.30
The ceramic capacitor for a fluorescent lamp ballast according to claim 1, wherein a sintering aid is contained as a sub-component with respect to the main component in the range of (1). The ceramic capacitor for a fluorescent lamp ballast according to claim 2, wherein the content of the sintering aid is 0.8 to 8.0 parts by weight based on 100 parts by weight of the main component. The ceramic capacitor for a ballast for a fluorescent lamp according to claim 1, further comprising a plurality of internal electrodes provided in the ceramic body. A ballast for a fluorescent lamp, comprising the ceramic capacitor according to claim 1.

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