JPH11307312A - Laminated varistor and manufacture thereof - Google Patents
Laminated varistor and manufacture thereofInfo
- Publication number
- JPH11307312A JPH11307312A JP10110930A JP11093098A JPH11307312A JP H11307312 A JPH11307312 A JP H11307312A JP 10110930 A JP10110930 A JP 10110930A JP 11093098 A JP11093098 A JP 11093098A JP H11307312 A JPH11307312 A JP H11307312A
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- Prior art keywords
- outer peripheral
- varistor
- peripheral portion
- laminated
- characteristic
- Prior art date
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Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、積層型バリスタ、
およびその製造方法に関する。TECHNICAL FIELD The present invention relates to a laminated varistor,
And its manufacturing method.
【0002】[0002]
【従来の技術】近年、電子機器の小型化や回路の高速化
により、これらに用いられる素子のチップ化や高周波化
が進んでいる。このような中、ノイズ吸収素子であるバ
リスタもチップ化が進み、ZnOやSrTiO3を主成
分としたチップタイプの積層型バリスタが登場してい
る。さらに、積層型バリスタは、回路の高密度化等の理
由からより一層の小型化、低背化が要求されている。2. Description of the Related Art In recent years, with the miniaturization of electronic devices and the speeding up of circuits, the elements used in these devices have been made into chips and higher frequencies. Under such circumstances, varistors serving as noise absorbing elements have also been formed into chips, and chip-type laminated varistors containing ZnO or SrTiO 3 as a main component have appeared. Further, the stacked varistor is required to be further reduced in size and height for reasons such as higher circuit density.
【0003】積層型バリスタにおいて、小型化や低背化
を進めるためには、電極面積当たりのサージ耐量を大き
くするか、あるいは、バリスタ材料の粒径を小さくする
ことによって積層数を増やし、有効電極面積を大きくす
る必要がある。しかしながら、これらの方法にも限界が
あり、サージ耐量を大きくするためには、積層型バリス
タの構造的問題点を解決する必要が出てきた。In order to reduce the size and height of the laminated varistor, the surge resistance per electrode area is increased, or the number of layers is increased by reducing the particle size of the varistor material, thereby increasing the number of effective electrodes. It is necessary to increase the area. However, these methods have limitations, and it is necessary to solve the structural problems of the multilayer varistor in order to increase the surge resistance.
【0004】従来の積層型バリスタにおける構造的問題
点とは、バリスタ特性が得られる特性部の周囲の外周部
にある。具体的には、以下のようなものである。[0004] A structural problem in the conventional multilayer varistor is the outer peripheral portion around the characteristic portion where the varistor characteristics can be obtained. Specifically, it is as follows.
【0005】1.通常の積層方法では、内部電極の厚み
により、積層圧着時に外周部に圧力がかかりにくく、密
度が小さくなりやすい。[0005] 1. In a normal laminating method, pressure is hardly applied to the outer peripheral portion during lamination and pressure-bonding, and the density is likely to be reduced due to the thickness of the internal electrode.
【0006】2.焼成時に熱や酸素拡散により外周部の
粒成長が促進され、バリスタ電圧が低くなりやすい。[0006] 2. During the firing, the growth of grains in the outer peripheral portion is promoted by diffusion of heat or oxygen, and the varistor voltage tends to be low.
【0007】外周部にこのような問題点があるため、特
性部の本来の特性が規制され、結果的にサージ耐量を抑
制していた。[0007] Due to such a problem in the outer peripheral portion, the original characteristics of the characteristic portion are regulated, and as a result, the surge withstand capability is suppressed.
【0008】そこで、このような問題を解決するものと
して、特開平5−29105号公報に開示されているよ
うな積層型バリスタがある。図4に示すように、この積
層型バリスタ20は、セラミック層23と、内部電極層
24と、外部電極25とからなり、バリスタ特性が得ら
れる特性部21と、特性部21以外の外周部22とから
構成されている。このうち、外周部22に副成分とし
て、Sb2O3、またはZn7Sb2O12が添加されてい
る。このような構成にすることによって、外周部のセラ
ミック層の粒子の粒成長が抑制され、外周部を緻密に
し、さらに、バリスタ電圧の低減を防止している。In order to solve such a problem, there is a multilayer varistor disclosed in Japanese Patent Application Laid-Open No. 5-29105. As shown in FIG. 4, the multilayer varistor 20 includes a ceramic layer 23, an internal electrode layer 24, and an external electrode 25, and a characteristic portion 21 for obtaining varistor characteristics and an outer peripheral portion 22 other than the characteristic portion 21. It is composed of Of these, Sb 2 O 3 or Zn 7 Sb 2 O 12 is added to the outer peripheral portion 22 as a sub-component. With such a configuration, the grain growth of the particles of the ceramic layer at the outer peripheral portion is suppressed, the outer peripheral portion is made denser, and further, the varistor voltage is prevented from being reduced.
【0009】[0009]
【発明が解決しようとする課題】従来の積層型バリスタ
には、その外周部に融点が656℃と低いSb2O3が副
成分として添加されているため、焼成中に溶融し、バリ
スタ材料の主成分であるZnOとパイロクロアを形成す
る。このため、拡散力が強いというメリットがある。し
かしながら、内部電極層と外部電極との接続部を覆う確
率も高く、接触不良を生じやすい。さらに、焼成時に積
層体同士の溶着の原因となるという問題点があった。In the conventional multilayer varistor, Sb 2 O 3 having a melting point as low as 656 ° C. is added as an auxiliary component to the outer periphery thereof. Pyrochlore is formed with ZnO as a main component. For this reason, there is an advantage that the diffusing power is strong. However, the probability of covering the connection between the internal electrode layer and the external electrode is high, and a contact failure is likely to occur. Further, there is a problem that the laminates may be welded to each other during firing.
【0010】本発明の目的は、積層型バリスタの外周部
が粒成長を起こすのを抑制し、外周部が特性部に与える
特性劣化を防止するとともに、焼成時における積層体同
士の溶着などの不具合を防止することのできる積層型バ
リスタを提供することにある。SUMMARY OF THE INVENTION It is an object of the present invention to suppress the occurrence of grain growth in the outer peripheral portion of a multilayer varistor, prevent the outer peripheral portion from deteriorating characteristics given to a characteristic portion, and to prevent defects such as welding between laminated members during firing. It is an object of the present invention to provide a laminated varistor that can prevent the occurrence of the varistor.
【0011】[0011]
【課題を解決するための手段】本発明は上記のような目
的に鑑みてなされたものである。第1の発明の積層型バ
リスタは、ZnOを主成分としたセラミック層と、前記
セラミック層上に形成された内部電極層とを積層した積
層体上に、前記内部電極層に電気的に接続するように外
部電極を形成した積層型バリスタであって、前記セラミ
ック層は、前記内部電極層が形成され、バリスタ特性が
得られる特性部と、前記特性部以外の外周部とからな
り、前記外周部には、Y,Ba,Sr,希土類元素から
選ばれる少なくとも1種類の酸化物または化合物(以
下、粒成長抑制剤とする)が存在していることを特徴と
する。SUMMARY OF THE INVENTION The present invention has been made in view of the above objects. According to a first aspect of the present invention, there is provided a multilayer varistor that is electrically connected to the internal electrode layer on a laminate in which a ceramic layer containing ZnO as a main component and an internal electrode layer formed on the ceramic layer are stacked. A multilayer varistor in which external electrodes are formed as described above, wherein the ceramic layer comprises a characteristic portion on which the internal electrode layer is formed and a varistor characteristic is obtained, and an outer peripheral portion other than the characteristic portion. Is characterized by the presence of at least one oxide or compound selected from Y, Ba, Sr and rare earth elements (hereinafter referred to as a grain growth inhibitor).
【0012】このような構成にすることによって、積層
型バリスタの外周部の粒成長を抑制することができ、サ
ージ耐量の低下などの特性部に対する影響を防止するこ
とができる。また、上記の酸化物または化合物を用いる
ことにより、バリスタ材料の主成分であるZnOと固相
反応し、外周部の表面近傍の絶縁性を高めることができ
る。さらに、これらは液相とならないため、内部電極と
外部電極との接触不良の心配はなく、焼成時における積
層体同士のくっつきもなくすことができる。With such a configuration, it is possible to suppress the grain growth on the outer peripheral portion of the multilayer varistor, and to prevent an influence on the characteristic portion such as a decrease in surge withstand capability. In addition, by using the above oxide or compound, a solid phase reaction occurs with ZnO, which is a main component of the varistor material, and the insulating property near the surface of the outer peripheral portion can be increased. Furthermore, since these do not become a liquid phase, there is no fear of poor contact between the internal electrode and the external electrode, and it is possible to prevent the laminates from sticking during firing.
【0013】第2の発明の積層型バリスタにおいては、
前記外周部の平均粒径r1と前記特性部の平均粒径r2と
の比r1/r2が0.8以下であることが好ましい。In the multilayer varistor of the second invention,
It is preferred ratios r 1 / r 2 of the average particle diameter r 2 of the mean particle size r 1 and the characteristic portion of the outer peripheral portion is 0.8 or less.
【0014】このような粒径にすることによって、積層
型バリスタのサージ耐量をより向上させることができ
る。With such a particle size, the surge withstand capability of the multilayer varistor can be further improved.
【0015】また、第3の発明の積層型バリスタの製造
方法は、バリスタ特性が得られる特性部と、前記特性部
以外の外周部とを有する積層型バリスタの製造方法であ
って、焼成以前、または焼成以前から焼成中にかけて、
前記外周部に粒成長抑制剤を存在させ、焼成時に拡散さ
せることを特徴とする。A third aspect of the present invention is a method of manufacturing a multilayer varistor having a characteristic portion capable of obtaining varistor characteristics and an outer peripheral portion other than the characteristic portion. Or before firing and during firing,
It is characterized in that a grain growth inhibitor is present in the outer peripheral portion and diffused during firing.
【0016】このような積層型バリスタの製造方法とす
ることによって、積層型バリスタの外周部に上記粒成長
抑制剤を容易に拡散させうるとともに、外周部の粒成長
を効果的に抑制し、サージ耐量を向上させた積層型バリ
スタを得ることができる。[0016] By adopting such a method of manufacturing a laminated varistor, the above-mentioned grain growth inhibitor can be easily diffused to the outer peripheral portion of the laminated varistor, and the grain growth at the outer peripheral portion can be effectively suppressed, and the surge can be suppressed. A laminated varistor with improved resistance can be obtained.
【0017】また、第4の発明の積層型バリスタの製造
方法においては、前記粒成長抑制剤を前記外周部にあた
る部分に印刷によって存在させることが好ましい。In the method of manufacturing a multilayer varistor according to a fourth aspect of the present invention, it is preferable that the grain growth inhibitor is present in a portion corresponding to the outer peripheral portion by printing.
【0018】また、第5の発明の積層型バリスタの製造
方法においては、前記粒成長抑制剤を前記特性部と前記
外周部とからなる積層体のバレリング時に、前記積層体
表面に付着させて存在させることが好ましい。In the method for manufacturing a multilayer varistor according to a fifth aspect of the present invention, the grain growth inhibitor is attached to a surface of the multilayer body during balleting of the multilayer body including the characteristic portion and the outer peripheral portion. Preferably.
【0019】このようにして粒成長抑制剤を配位するこ
とによって、粒成長抑制剤を一様に外周部に拡散させる
ことができ、確実に外周部の粒成長を抑制させることが
できる。By coordinating the grain growth inhibitor in this manner, the grain growth inhibitor can be uniformly diffused to the outer peripheral portion, and the grain growth at the outer peripheral portion can be surely suppressed.
【0020】[0020]
【発明の実施の形態】本発明の積層型バリスタは、特性
部と外周部とからなるセラミック層と、そのセラミック
層上に形成された内部電極層とを積層して積層体とし、
その積層体上に外部電極が形成されている。BEST MODE FOR CARRYING OUT THE INVENTION A laminated varistor according to the present invention comprises a laminated body obtained by laminating a ceramic layer comprising a characteristic portion and an outer peripheral portion and an internal electrode layer formed on the ceramic layer.
External electrodes are formed on the laminate.
【0021】ここで、本発明の積層型バリスタに用いら
れるセラミック層は、ZnOを主成分としたものであれ
ばよい。ZnOを主成分としないものは、化合物の反応
が必ずしも絶縁性でないという点から好ましくない。Here, the ceramic layer used in the multilayer varistor of the present invention may be any one containing ZnO as a main component. Those containing no ZnO as a main component are not preferable because the reaction of the compound is not always insulating.
【0022】また、セラミック層のうち特性部は、バリ
スタ特性が得られる部分、すなわち異なる極性の内部電
極層によって挟まれた部分である。したがって、内部電
極層が形成された部分が必ずしも特性部であるというわ
けではない。また、セラミック層のうち外周部は、セラ
ミック層のうち特性部以外の部分を指し、特性部を覆う
構造になっている。The characteristic portion of the ceramic layer is a portion where varistor characteristics are obtained, that is, a portion sandwiched by internal electrode layers having different polarities. Therefore, the portion where the internal electrode layer is formed is not always the characteristic portion. The outer peripheral portion of the ceramic layer indicates a portion other than the characteristic portion of the ceramic layer, and has a structure covering the characteristic portion.
【0023】また、外周部に拡散させる粒成長抑制剤
は、セラミックグリーンシートを積層する前にペースト
状にしてセラミックグリーンシート上に塗布するか、積
層後、積層体をバレリングする際に積層体表面に付着さ
せ、積層体の焼成時に外周部に拡散させることが好まし
い。なお、粒成長抑制剤をセラミックグリーンシート上
に塗布する方法としては、スクリーン印刷やスパッタリ
ング等が挙げられる。The grain growth inhibitor to be diffused to the outer peripheral portion is formed into a paste before laminating the ceramic green sheets and is applied on the ceramic green sheets. , And diffused to the outer periphery during firing of the laminate. In addition, as a method of applying the grain growth inhibitor on the ceramic green sheet, screen printing, sputtering and the like can be mentioned.
【0024】なお、焼成後に粒成長抑制剤を拡散させて
も、焼成後では、すでに外周部の粒成長が起こってお
り、外周部の粒径は小さくならず好ましくない。Even if the grain growth inhibitor is diffused after firing, grain growth at the outer peripheral portion has already occurred after firing, and the particle size at the outer peripheral portion is not small, which is not preferable.
【0025】次に、本発明を実施例を用いてさらに具体
的に説明する。Next, the present invention will be described more specifically with reference to examples.
【0026】[0026]
【実施例】(実施例1)本発明の積層型バリスタの製造
方法について説明する。図1は本発明である積層型バリ
スタの概略断面図、図2は実施例1の積層体の分解斜視
図を示す。まず、セラミック層となるバリスタ材料の出
発原料として、主成分であるZnOと、これに対して、
Bi2O31.0mol%、MnO0.5mol%、CoO0.
5mol%、SiO21.0mol%、B2O30.1mol%、S
b2O30.5mol%、Al2O3100ppmとを配合し、バ
リスタ材料とした。(Embodiment 1) A method of manufacturing a multilayer varistor according to the present invention will be described. FIG. 1 is a schematic sectional view of a laminated varistor according to the present invention, and FIG. 2 is an exploded perspective view of the laminated body of the first embodiment. First, as a starting material of a varistor material to be a ceramic layer, ZnO as a main component, and
Bi 2 O 3 1.0mol%, MnO0.5mol %, CoO0.
5mol%, SiO 2 1.0mol%, B 2 O 3 0.1mol%, S
b 2 O 3 0.5mol%, blended and Al 2 O 3 100ppm, and the varistor material.
【0027】次に、得られたバリスタ材料をボールミル
で20時間混合・粉砕した後、脱水を行い、乾燥後60
メッシュの篩いで造粒し造粒物とした。この造粒物を7
50℃で2時間仮焼した後、粗粉砕し、再度ボールミル
で混合・粉砕して仮焼粉体を得た。さらに、得られた仮
焼粉体に溶剤、バインダー、分散剤を加え、厚さ50μ
mの成形体とした。次にこの成形体を所定の大きさに打
ち抜いてセラミックグリーンシートを得た。Next, the obtained varistor material is mixed and pulverized by a ball mill for 20 hours, dewatered, dried, and dried for 60 hours.
Granulation was performed using a mesh sieve to obtain a granulated product. 7
After calcining at 50 ° C. for 2 hours, the mixture was roughly pulverized, mixed and pulverized again with a ball mill to obtain a calcined powder. Further, a solvent, a binder, and a dispersant were added to the obtained calcined powder, and a thickness of 50 μm was added.
m. Next, the formed body was punched into a predetermined size to obtain a ceramic green sheet.
【0028】次に、図2に示すように、得られたセラミ
ックグリーンシート7の一部に、スクリーン印刷法によ
りPtペーストを印刷し、内部電極層13とした。Next, as shown in FIG. 2, a Pt paste was printed on a part of the obtained ceramic green sheet 7 by a screen printing method to form an internal electrode layer 13.
【0029】次に、内部電極層13を印刷したセラミッ
クグリーンシート7の特性部9を除いた外周部11に、
BaTiO3,SrTiO3,Sb2O3,Y2O3,希土類
酸化物をペースト状とした粒成長抑制剤15をそれぞれ
約2μmの厚みでスクリーン印刷した。また、内部電極
層13を印刷しなかったセラミックグリーンシート7の
片面全面に上記の要領で粒成長抑制剤11をスクリーン
印刷し、これら2種類のセラミックグリーンシート7を
所定の順、方向に積層し、積層体3とした。Next, on the outer peripheral portion 11 of the ceramic green sheet 7 on which the internal electrode layer 13 is printed, excluding the characteristic portion 9,
BaTiO 3 , SrTiO 3 , Sb 2 O 3 , Y 2 O 3 , and a grain growth inhibitor 15 in the form of a paste of a rare earth oxide were screen-printed to a thickness of about 2 μm. The grain growth inhibitor 11 is screen-printed on the entire surface of one side of the ceramic green sheet 7 on which the internal electrode layer 13 is not printed in the above-described manner, and these two types of ceramic green sheets 7 are laminated in a predetermined order and direction. And a laminate 3.
【0030】さらに、得られた積層体3を500℃で脱
脂した後、900℃で3時間焼成し、積層焼結体を得
た。そして、図1に示すように、セラミック層5と内部
電極層13とからなる積層焼結体の内部電極層13が露
出した側面にAgペーストを800℃で焼き付けて外部
電極17を形成し、積層型バリスタ1とした。Further, after the obtained laminate 3 was degreased at 500 ° C., it was baked at 900 ° C. for 3 hours to obtain a laminated sintered body. Then, as shown in FIG. 1, an external electrode 17 is formed by baking Ag paste at 800 ° C. on the side surface of the laminated sintered body including the ceramic layer 5 and the internal electrode layer 13 where the internal electrode layer 13 is exposed. The mold varistor 1 was used.
【0031】上記のようにして得られる積層型バリスタ
のサージ耐量、および外周部の粒径r1と特性部の粒径
r2との比r1/r2を測定し、積層体を焼成した際の溶
着の有無を調べた。その結果を表1に示す。なお、サー
ジ耐量は、積層型バリスタに電圧を5分間隔で2回印加
し、1分間放置した後測定した。また、外周部の粒径r
1および特性部の粒径r2の粒径は、試料を研磨した後、
熱エッチングして測定した。さらに、粒成長抑制剤にS
b2O3を用いたものと、粒成長抑制剤を用いないものを
比較例とした。The surge resistance of the multilayer varistor obtained as described above, and the ratio r 1 / r 2 of the particle size r 2 of the particle size r 1 and the characteristic portion of the outer peripheral portion was measured and firing the laminate The presence or absence of welding at the time was examined. Table 1 shows the results. The surge withstand capability was measured after applying a voltage to the laminated varistor twice at 5 minute intervals and allowing the varistor to stand for 1 minute. Also, the particle diameter r of the outer peripheral portion
The particle size of 1 and the particle size r 2 of the characteristic part is determined after polishing the sample.
It was measured by thermal etching. Furthermore, S is added to the grain growth inhibitor.
Comparative examples using b 2 O 3 and those using no grain growth inhibitor were used as comparative examples.
【0032】[0032]
【表1】 [Table 1]
【0033】表1に示すように、上記のような製造方法
で、粒成長抑制剤を外周部に配位、拡散させたものは、
粒成長抑制剤を用いない比較例2に比べ、サージ耐量が
大幅に向上していることが確認できる。なお、粒成長抑
制剤にSb2O3を用いたものは、焼成時に積層体同士の
溶着が生じるため好ましくない。As shown in Table 1, in the production method as described above, the one in which the grain growth inhibitor was coordinated and diffused in the outer peripheral portion was:
It can be confirmed that the surge resistance is significantly improved as compared with Comparative Example 2 in which no grain growth inhibitor was used. It should be noted that the use of Sb 2 O 3 as the grain growth inhibitor is not preferable because the laminates are welded to each other during firing.
【0034】(実施例2)図1は本発明である積層型バ
リスタの概略断面図、図3は実施例2の積層体の分解斜
視図を示す。図3に示すように、実施例1と同様にして
得たセラミックグリーンシート7の一部に、スクリーン
印刷法によりPtペーストを印刷し、内部電極層13と
した。(Embodiment 2) FIG. 1 is a schematic sectional view of a laminated varistor according to the present invention, and FIG. 3 is an exploded perspective view of a laminated body of Embodiment 2. As shown in FIG. 3, a Pt paste was printed on a part of the ceramic green sheet 7 obtained in the same manner as in Example 1 by a screen printing method to form an internal electrode layer 13.
【0035】次に、内部電極層13を印刷したセラミッ
クグリーンシート7と、内部電極層13を印刷しなかっ
たセラミックグリーンシート7の2種類のセラミックグ
リーンシート7を所定の順、方向に積層し、積層体3と
した。Next, two types of ceramic green sheets 7, a ceramic green sheet 7 on which the internal electrode layer 13 is printed and a ceramic green sheet 7 on which the internal electrode layer 13 is not printed, are laminated in a predetermined order and direction. The laminate 3 was obtained.
【0036】この後、得られた積層体3と、BaTiO
3,SrTiO3,Sb2O3,Y2O3,希土類酸化物から
なる粒成長抑制剤とを、玉石とともにポリポット内に入
れて回転させ、バレリングを行うと同時に、積層体3の
表面に粒成長抑制剤を付着させた。Thereafter, the obtained laminated body 3 and BaTiO 3
3 , SrTiO 3 , Sb 2 O 3 , Y 2 O 3 , and a grain growth inhibitor consisting of a rare earth oxide are put together with a cobblestone in a polypot and rotated to perform balling, and at the same time, to the surface of the laminate 3 A growth inhibitor was deposited.
【0037】さらに、粒成長抑制剤を付着させた積層体
3を500℃で脱脂した後、900℃で3時間焼成し、
積層焼結体を得た。そして、図1に示すように、得られ
た積層焼結体の内部電極層13が露出した側面にAgペ
ーストを800℃で焼き付けて外部電極17を形成し、
積層型バリスタ1とした。Further, the laminate 3 to which the grain growth inhibitor has been adhered is degreased at 500 ° C., and baked at 900 ° C. for 3 hours.
A laminated sintered body was obtained. Then, as shown in FIG. 1, an external electrode 17 is formed by baking an Ag paste at 800 ° C. on the side surface of the obtained laminated sintered body where the internal electrode layer 13 is exposed,
The laminated varistor 1 was used.
【0038】上記のようにして得られた積層型バリスタ
について、実施例1と同様にサージ耐量、および外周部
の粒径r1と特性部の粒径r2との比r1/r2を測定し
た。その結果を表2に示す。[0038] A multilayer varistor obtained as described above, similarly surge resistance as in Example 1, and the ratio r 1 / r 2 of the particle size r 2 of the particle size r 1 and the characteristic portion of the outer peripheral portion It was measured. Table 2 shows the results.
【0039】[0039]
【表2】 [Table 2]
【0040】表2に示すように、実施例2における製造
方法であっても、外周部に粒成長抑制剤を拡散させ、外
周部の粒成長を抑えて、表1の比較例2に比べ、積層型
バリスタのサージ耐量が向上していることを確認でき
る。As shown in Table 2, even in the production method in Example 2, the grain growth inhibitor was diffused in the outer peripheral portion to suppress the grain growth in the outer peripheral portion. It can be confirmed that the surge immunity of the multilayer varistor is improved.
【0041】(実施例3)実施例1と同様の製造方法を
用いて作製した積層型バリスタのうち、粒成長抑制剤を
Y2O3とし、その塗布厚さを変化させて外周部の粒径を
変化させて外周部粒径/特性部粒径を変化させた。さら
に、そのときのサージ耐量を測定し、その結果を表3に
示す。なお、表中の※印は本発明の範囲外である。(Example 3) Among the laminated varistors manufactured using the same manufacturing method as in Example 1, the grain growth inhibitor was Y 2 O 3 , and the coating thickness was changed to change the grain size at the outer peripheral portion. The diameter was changed to change the outer peripheral part particle diameter / characteristic part particle diameter. Further, the surge withstand capability at that time was measured, and the results are shown in Table 3. Note that the asterisks in the table are outside the scope of the present invention.
【0042】[0042]
【表3】 [Table 3]
【0043】表3に示すように、請求項1において、外
周部の平均粒径r1と特性部の平均粒径r2との比r1/
r2を0.8以下に限定したのは、試料番号44のよう
に、外周部の平均粒径r1と特性部の平均粒径r2との比
r1/r2が0.8より大きい場合には、サージ耐量が大
きくならず好ましくないからである。[0043] Table as shown in 3, in claim 1, the ratio r between the average particle diameter r 2 of the mean particle size r 1 and the characteristic portion of the outer peripheral portion 1 /
The reason for limiting the r 2 to 0.8 or less, as in sample No. 44, the average particle diameter r 1 and a ratio r 1 / r 2 of the average particle diameter r 2 of the characteristic portion of the outer peripheral portion than 0.8 This is because if it is large, the surge withstand capacity is not increased, which is not preferable.
【0044】[0044]
【発明の効果】本発明の積層型バリスタは、ZnOを主
成分としたセラミック層と、セラミック層上に形成され
た内部電極層とを積層した積層体上に、内部電極層に電
気的に接続するように外部電極を形成した構成である。
このうち、セラミック層は、内部電極層が形成され、バ
リスタ特性が得られる特性部と、特性部以外の外周部と
からなり、外周部には、Y,Ba,Sr,希土類元素か
ら選ばれる少なくとも1種類の酸化物または化合物が存
在するようにしている。The multilayer varistor of the present invention is electrically connected to an internal electrode layer on a laminate in which a ceramic layer mainly composed of ZnO and an internal electrode layer formed on the ceramic layer are stacked. This is a configuration in which external electrodes are formed in such a manner.
Among these, the ceramic layer is formed of a characteristic portion on which an internal electrode layer is formed and varistor characteristics are obtained, and an outer peripheral portion other than the characteristic portion. The outer peripheral portion includes at least one selected from Y, Ba, Sr, and a rare earth element. One type of oxide or compound is present.
【0045】また、本発明の積層型バリスタの製造方法
は、焼成以前、または焼成以前から焼成中にかけて、外
周部にY,Ba,Sr,希土類元素から選ばれる少なく
とも1種類の酸化物または化合物を存在させ、焼成時に
拡散させている。The method of manufacturing a laminated varistor according to the present invention is characterized in that at least one oxide or compound selected from the group consisting of Y, Ba, Sr and a rare earth element is added to the outer periphery before firing or before firing and during firing. It is present and diffused during firing.
【0046】上記のような構成または製造方法としてい
るので、積層型バリスタの外周部に粒成長抑制剤を存在
させた後、拡散させて、外周部が粒成長を起こすのを抑
制し、外周部が特性部に与える特性劣化を防止するとと
もに、焼成時における積層体同士の溶着などの不具合を
防止することができる。Since the above configuration or manufacturing method is adopted, a grain growth inhibitor is made to exist in the outer peripheral portion of the multilayer varistor and then diffused to suppress the occurrence of grain growth in the outer peripheral portion. Can prevent characteristic deterioration given to the characteristic portion, and also prevent problems such as welding of the laminates during firing.
【図1】本発明の積層型バリスタを示す概略断面図。FIG. 1 is a schematic sectional view showing a laminated varistor of the present invention.
【図2】第1実施例の積層型バリスタにおける積層体を
示す分解斜視図。FIG. 2 is an exploded perspective view showing a multilayer body in the multilayer varistor of the first embodiment.
【図3】第2実施例の積層型バリスタにおける積層体を
示す分解斜視図。FIG. 3 is an exploded perspective view showing a multilayer body in the multilayer varistor of the second embodiment.
【図4】従来の積層型バリスタを示す概略断面図。FIG. 4 is a schematic sectional view showing a conventional laminated varistor.
1 積層型バリスタ 3 積層体 5 セラミック層 7 セラミックグリーンシート 9 特性部 11 外周部 13 内部電極層 15 粒成長抑制剤 17 外部電極 REFERENCE SIGNS LIST 1 laminated varistor 3 laminated body 5 ceramic layer 7 ceramic green sheet 9 characteristic portion 11 outer peripheral portion 13 internal electrode layer 15 grain growth inhibitor 17 external electrode
───────────────────────────────────────────────────── フロントページの続き (72)発明者 羽田野 研次郎 京都府長岡京市天神二丁目26番10号 株式 会社村田製作所内 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenjiro Hatano 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Inside Murata Manufacturing Co., Ltd.
Claims (5)
前記セラミック層上に形成された内部電極層とを積層し
た積層体上に、前記内部電極層に電気的に接続するよう
に外部電極を形成した積層型バリスタであって、 前記セラミック層は、前記内部電極層が形成され、バリ
スタ特性が得られる特性部と、前記特性部以外の外周部
とからなり、前記外周部には、Y,Ba,Sr,希土類
元素から選ばれる少なくとも1種類の酸化物または化合
物が存在していることを特徴とする積層型バリスタ。1. A ceramic layer containing ZnO as a main component,
A multilayer varistor in which external electrodes are formed on a laminate obtained by laminating an internal electrode layer formed on the ceramic layer so as to be electrically connected to the internal electrode layer, wherein the ceramic layer is An internal electrode layer is formed, comprising a characteristic portion from which varistor characteristics are obtained and an outer peripheral portion other than the characteristic portion, wherein the outer peripheral portion has at least one oxide selected from the group consisting of Y, Ba, Sr, and a rare earth element. Alternatively, a laminated varistor characterized in that a compound is present.
の平均粒径r2との比r1/r2が0.8以下であること
を特徴とする請求項1に記載の積層型バリスタ。2. The method according to claim 1 , wherein a ratio r 1 / r 2 between the average particle diameter r 1 of the outer peripheral portion and the average particle diameter r 2 of the characteristic portion is 0.8 or less. Stacked varistor.
特性部以外の外周部とを有する積層型バリスタの製造方
法であって、 焼成以前、または焼成以前から焼成中にかけて、前記外
周部にY,Ba,Sr,希土類元素から選ばれる少なく
とも1種類の酸化物または化合物を存在させ、焼成時に
拡散させることを特徴とする積層型バリスタの製造方
法。3. A method for manufacturing a laminated varistor having a characteristic portion capable of obtaining varistor characteristics and an outer peripheral portion other than the characteristic portion, wherein Y is applied to the outer peripheral portion before firing or before firing and during firing. , Ba, Sr, and a rare earth element, wherein at least one kind of oxide or compound is present and diffused during firing.
ばれる少なくとも1種類の酸化物または化合物を前記外
周部にあたる部分に印刷によって存在させることを特徴
とする請求項3に記載の積層型バリスタの製造方法。4. The multilayer varistor according to claim 3, wherein at least one oxide or compound selected from the group consisting of Y, Ba, Sr, and a rare earth element is present in a portion corresponding to the outer peripheral portion by printing. Manufacturing method.
ばれる少なくとも1種類の酸化物または化合物を前記特
性部と前記外周部とからなる積層体のバレリング時に、
前記積層体表面に付着して存在させることを特徴とする
請求項3に記載の積層型バリスタの製造方法。5. The method according to claim 1, wherein at least one oxide or compound selected from the group consisting of Y, Ba, Sr, and a rare earth element is balleted in a laminate comprising the characteristic portion and the outer peripheral portion.
The method for manufacturing a multilayer varistor according to claim 3, wherein the multilayer varistor is attached to a surface of the multilayer body.
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