JP3551780B2 - Varistor and manufacturing method thereof - Google Patents
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- JP3551780B2 JP3551780B2 JP25825398A JP25825398A JP3551780B2 JP 3551780 B2 JP3551780 B2 JP 3551780B2 JP 25825398 A JP25825398 A JP 25825398A JP 25825398 A JP25825398 A JP 25825398A JP 3551780 B2 JP3551780 B2 JP 3551780B2
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- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 238000010304 firing Methods 0.000 claims description 19
- 150000001875 compounds Chemical class 0.000 claims description 14
- 239000002184 metal Substances 0.000 claims description 13
- 229910052751 metal Inorganic materials 0.000 claims description 13
- 229910015902 Bi 2 O 3 Inorganic materials 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 10
- 239000002003 electrode paste Substances 0.000 claims description 7
- 238000002844 melting Methods 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 4
- 238000005245 sintering Methods 0.000 description 17
- 230000000694 effects Effects 0.000 description 14
- 230000015572 biosynthetic process Effects 0.000 description 8
- 239000007791 liquid phase Substances 0.000 description 6
- 239000013078 crystal Substances 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- -1 Co 2 O 3 Inorganic materials 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
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Description
【０００１】
【発明の属する技術分野】
本発明は各種電子機器を異常高電圧から保護するバリスタおよびその製造方法に関するものである。
【０００２】
【従来の技術】
従来のバリスタは、主成分のＺｎＯに副成分としてＢｉ２Ｏ３，Ｃｏ２Ｏ３，ＭｎＯ２，Ａｌ２Ｏ３等を含むバリスタ材料の成形体を、１１５０〜１３５０℃の温度で焼成した後、焼結体の両面に電極ペーストを印刷、焼付けを行いバリスタを完成させていた。
【０００３】
【発明が解決しようとする課題】
前記バリスタ材料は実用的なバリスタ特性を得るには１１５０℃より高い温度で焼成する必要がある。このためＡｇ又はＡｇ−Ｐｄ化合物を主成分とする電極ペーストを成形体に塗布し、成形体と電極とを１１５０℃より高い温度で一体焼成を行うと、電極金属成分のＡｇが溶融凝集したり、Ｐｄが組成中のＢｉ２Ｏ３と反応し電極としての機能が消失してしまう。従って電極の形成は成形体の焼成と別個に行わなければならないという問題があった。
【０００４】
本発明はこの問題点を解決するもので、成形体の焼結と電極形成を同時に行うことのできるバリスタおよびその製造方法を提供することを目的とするものである。
【０００５】
【課題を解決するための手段】
前記課題を解決する本発明のバリスタは、主成分のＺｎＯに副成分として少なくともＢｉ２Ｏ３と、Ｓｂ２Ｏ３を含む組成物に、更にＭｎ化合物を溶液の形でＭｎがＺｎＯに対し０．０１〜１．０ａｔ％の範囲で添加した材料を用いた成形体を８５０〜１１００℃の温度で焼成したバリスタ素子を用いたものである。この構成とすることにより溶液の形で添加したＭｎ化合物は成形体の焼成過程で、熱分解し活性度の高いＭｎＯ２となり、これがＢｉ２Ｏ３と容易に反応し成形体の焼結開始温度を低温側に押し下げる効果があり、この結果、バリスタの成形体を比較的低い８５０〜１１００℃の温度でも焼結させることができ、従って成形体の焼結と電極形成を同時に行うことができると共に、低温焼成によって主成分のＺｎＯ結晶粒径が均一な大きさとなり、得られたバリスタはバリスタ電圧のバラツキ（標準偏差σ）が小さくなり歩留まりも向上するという効果がある。
【０００６】
【発明の実施の形態】
本発明の請求項１に記載の発明は、ＺｎＯを主成分とし副成分として少なくともＢｉ２Ｏ３とＳｂ２Ｏ３を含む組成物に、更にＭｎ化合物の溶液の形でＭｎがＺｎＯに対し０．０１〜１．０ａｔ％の範囲となるように添加した材料の成形体を８５０〜１１００℃の温度で焼成したバリスタ素子を用いたバリスタである。溶液の形で添加したＭｎ化合物は成形体の焼成過程の６００℃近傍の温度で熱分解し化学的活性が高いＭｎＯ２となり、これが組成物中のＢｉ２Ｏ３と容易に反応し比較的低温度で液相を生成し、この液相がＺｎＯと反応し焼結開始温度を低下させる効果があり、このため、従来の焼成温度より低い８５０〜１１００℃の温度でも焼結が可能となり、従って、成形体の焼結と電極形成を同時に行うことができると共に、低温で焼結を行うため主成分のＺｎＯ結晶粒径が均一な大きさに成長し、バリスタ電圧のバラツキを小さくし、特性歩留まりを向上させると言う作用をも有するものである。
【０００７】
本発明の請求項２に記載の発明は、Ｍｎ化合物としてＭｎ（ＮＯ３）２またはＭｎＳＯ４を溶液の形で用いた請求項１に記載のバリスタである。溶液の状態で添加し前記効果が得られるＭｎ化合物の材料を規定したものであると共に、溶液の状態で添加することにより微量なＭｎの分散性を向上させることができるという作用を有するものである。
【０００８】
本発明の請求項３に記載の発明は、電極金属成分としてＡｇまたはＡｇ−Ｐｄ化合物を用いた請求項１に記載のバリスタである。８５０〜１１００℃の温度範囲でバリスタ成形体との一体焼結が可能な電極金属成分を規定したものである。
【０００９】
本発明の請求項４に記載の発明は、成形体の両面に融点が８５０℃以上の金属成分を主成分とする電極ペーストを印刷塗布後、成形体と電極を一体焼成することを特徴とする請求項１に記載のバリスタの製造方法である。前項で説明したように本発明のバリスタ組成物は８５０〜１１００℃の低温で焼結が可能であるため、融点が８５０℃以上の金属成分からなる電極ペーストを成形体に塗布し、成形体の焼結と電極形成を同時に行うことが可能となるものである。
【００１０】
以下本発明の一実施の形態について説明する。
（実施の形態１）
図１に本発明の一実施の形態のバリスタを示す。図１において１はバリスタ素子、２ａ，２ｂは電極である。
【００１１】
このバリスタの製造方法について以下に説明する。先ず、主成分のＺｎＯに、副成分としてＢｉ２Ｏ３を０．５ｍｏｌ％、Ｓｂ２Ｏ３を０．２５ｍｏｌ％、Ｃｏ２Ｏ３を０．５ｍｏｌ％、Ａｌ２Ｏ３を０．００５ｍｏｌ％含む組成物に、更にＭｎ（ＮＯ３）２溶液をＭｎがＺｎＯに対し０．００５〜１．５ａｔ％の範囲となるように添加、混合した後、脱水乾燥を行う。得られた各バリスタ材料にポリビニルアルコールを加えて造粒を行う。
【００１２】
次に、各造粒粉を８０ＭＰａ／ｃｍ２の成形圧力で、直径１５ｍｍ、厚さ１．５ｍｍの円板を成形した後、夫々の成形体の両面にＡｇを主成分とする電極ペーストをスクリーン印刷法を用いて直径１０ｍｍの電極２ａ，２ｂの印刷を行い、９５０℃の温度で５時間、成形体と電極２ａ，２ｂの一体焼成を行いバリスタを作製した。比較例としてＭｎ（ＮＯ３）２に代えて、ＭｎＯ２を用いＭｎをＺｎＯに対し０．００５〜１．５ａｔ％の範囲で添加した材料についても同条件で処理してバリスタを作製した。
【００１３】
得られた夫々のバリスタに１ｍＡ及び１０μＡの電流を流したときのバリスタ電圧を測定し、これから厚さ１ｍｍ当たりのバリスタ電圧（Ｖ１ｍＡ／ｍｍ）、及び電圧非直線係数（α）を算出し、その結果を（表１）に示した。尚、電圧非直線係数αは（数１）より求めたものである。
【００１４】
【表１】
【数１】
（表１）に示すように、Ｍｎ（ＮＯ３）２の溶液の形でのＭｎをＺｎＯに対し０．０１から１．０ａｔ％の範囲で添加したものは、バリスタ電圧のバラツキ（標準偏差σ）が小さく、電圧非直線性が高い。これに対しＭｎの添加量が０．０１ａｔ％より少ない場合、バリスタ電圧が高過ぎ実用的ではなく、またバリスタ電圧のバラツキも大きい。また、Ｍｎの添加量が１．０ａｔ％より多い場合、電圧非直線性が極めて小さくなる。一方Ｍｎ（ＮＯ３）２の代わりにＭｎＯ２を用いた場合は、同じＭｎの添加量であるにも拘らずバリスタ電圧が高く、バリスタ電圧のバラツキが大きいことがわかる。
【００１７】
また、前記組成物の内、Ｍｎを添加量０．５ａｔ％とした組成について、８００から１０００℃の各温度で３０分間焼成し、各温度における焼成収縮率を測定しその結果を図２に示した。
【００１８】
図２から明らかなように、ＭｎをＭｎ（ＮＯ３）２の溶液の形で添加した場合、粉末状態のＭｎＯ２の形で添加した場合よりも低い温度で、成形体の焼成収縮が始り比較的低い温度で焼結反応が終了することがわかる。これは、溶液の形で添加したＭｎ（ＮＯ３）２が成形体の焼結過程の６００℃近傍温度で熱分解し、化学的活性度の高いＭｎＯ２微粒子を生成する。これが組成中のＢｉ２Ｏ３と反応し比較的低い温度で液相を生成する。この液相がＺｎＯと反応し焼結開始温度を低下させるものと思われる。従って、従来の焼成温度より低い８５０〜１１００℃の温度でも成形体の焼結を終了させることができることを示している。
【００１９】
この結果から推測すると、本実施の形態のＭｎの添加量が０．０１ａｔ％より少ない場合、活性度の高いＭｎＯ２が少なく、ＭｎＯ２とＢｉ２Ｏ３とで生成される液相が少なく、９５０℃でＺｎＯの結晶粒成長促進効果が不十分となり、バリスタ焼結体が末焼結の状態であることを示しているものと思われる。しかしながら１．０ａｔ％より多い場合、電圧非直線性が小さくなる理由については解析が十分になされていないため定かではない。
【００２０】
以上の結果から１１００℃以下の焼成温度で、電圧非直線係数が大きく、しかもバリスタ電圧のバラツキが小さい焼結体を得るためには、ＭｎをＭｎ（ＮＯ３）２溶液の形で０．０１〜１．０ａｔ％の範囲で添加する必要があることがわかる。尚、本実施の形態ではＭｎ（ＮＯ３）２の溶液の形で添加したが、これをＭｎＳＯ４の溶液を用いても同様な効果が得られることを確認している。
【００２１】
（実施の形態２）
先ず、実施の形態１で作製したＭｎ（ＮＯ３）２の形でＭｎをＺｎＯに対し０．１ａｔ％添加した造粒粉を用い、８０ＭＰａ／ｃｍ２の成形圧力で直径１５ｍｍ、厚さ１．５ｍｍの円板状に成形を行った。
【００２２】
次に、成形体の両面に（表２）に示す組成の電極ペーストを用い、直径１０ｍｍの電極２ａ，２ｂをスクリーン印刷した。
【００２３】
次いで、８５０から１１００℃の温度で３０分間、成形体の焼結と電極２ａ，２ｂの形成を同時に行いバリスタを作製した。得られたバリスタの電極２ａ，２ｂの形成状態を評価し、その結果を（表２）に示した。
【００２４】
【表２】
（表２）に示したように、電極２ａ，２ｂの金属成分がＡｇのみの場合、焼成温度がＡｇの溶融温度９６０℃を超えるとＡｇが溶融凝縮してしまい電極２ａ，２ｂとしての機能を果たさなくなる。一方金属成分のＡｇにＰｄを添加することにより１１００℃までは電極機能を保つことはできるが、焼成温度が１１００℃を超えるとバリスタ材料成分中のＢｉ２Ｏ３と電極２ａ，２ｂの成分のＰｄが反応し電極２ａ，２ｂとしての機能が消失し好ましくない。
【００２６】
また、何れの場合においても、８５０℃より低い温度では電極２ａ，２ｂの形成状態は良好であるが、バリスタ素子１の焼結が不十分でバリスタ電圧が高くなり過ぎ実用的でなくなる。このため電極２ａ，２ｂの金属成分がＡｇのみの場合は８５０℃〜９５０℃の温度範囲、ＡｇにＰｄを添加した場合は８５０〜１１００℃で焼成することを行うことによって、実用に適するバリスタ特性を有するバリスタを得ることが可能となる。
【００２７】
尚、本実施の形態では電極金属成分にＡｇとＡｇ−Ｐｄ化合物を用いたが、本発明のバリスタ成形体の焼成温度範囲で溶融せず、またバリスタ材料成分中の構成元素と反応しない金属であれば、その他の金属を使用しても良い。
【００２８】
【発明の効果】
以上本発明によれば、主成分のＺｎＯに副成分として少なくともＢｉ２Ｏ３，Ｓｂ２Ｏ３を含むバリスタ組成物に、さらにＭｎ化合物を溶液の形でＭｎがＺｎＯに対し０．０１〜１．０ａｔ％の範囲で添加することによって、このバリスタ材料は焼成過程の６００℃近傍の温度で溶液の形で添加したＭｎ化合物が分解し活性度の高いＭｎＯ２の微粒子となり、これが成分中のＢｉ２Ｏ３と反応し、比較的低い温度で液相を生成し焼結開始温度を低下させる効果がある。従って８５０〜１１００℃の焼成温度で、成形体焼結と電極形成を同時に行うことが可能となる。また、得られた焼成体は均一なＺｎＯ結晶粒で構成され、電圧非直線性が大きくしかもバリスタ電圧のバラツキが小さくなり特性歩留まりが向上する。
【図面の簡単な説明】
【図１】本発明の一実施の形態のバリスタの製造方法により得たバリスタの断面図
【図２】本発明の組成の焼成温度と焼結体収縮率の関係を示す図
【符号の説明】
１ バリスタ素子
２ａ 電極
２ｂ 電極[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a varistor for protecting various electronic devices from abnormally high voltage and a method for manufacturing the varistor.
[0002]
[Prior art]
Conventional varistor, a shaped body of the varistor material containing Bi 2 O 3, Co 2 O 3,
[0003]
[Problems to be solved by the invention]
The varistor material must be fired at a temperature above 1150 ° C. to obtain practical varistor properties. For this reason, when an electrode paste containing Ag or an Ag-Pd compound as a main component is applied to a molded body and the molded body and the electrode are integrally fired at a temperature higher than 1150 ° C., Ag of the electrode metal component may melt and aggregate. , Pd reacts with Bi 2 O 3 in the composition and the function as an electrode is lost. Therefore, there is a problem that the formation of the electrode must be performed separately from the firing of the molded body.
[0004]
An object of the present invention is to solve this problem, and an object of the present invention is to provide a varistor capable of simultaneously performing sintering of a compact and forming an electrode, and a method of manufacturing the varistor.
[0005]
[Means for Solving the Problems]
The varistor of the present invention that solves the above-mentioned problem is characterized in that a composition containing at least Bi 2 O 3 and Sb 2 O 3 as subcomponents in ZnO as a main component and a Mn compound in the form of a solution further containing Mn in the form of a solution containing 0% of ZnO. A varistor element obtained by firing a molded body using a material added in the range of 0.01 to 1.0 at% at a temperature of 850 to 1100 ° C. With this configuration, the Mn compound added in the form of a solution is thermally decomposed into MnO 2 having a high activity during the firing process of the molded body, which easily reacts with Bi 2 O 3 to start sintering of the molded body. Has the effect of lowering the temperature of the varistor to a lower temperature. As a result, the varistor compact can be sintered even at a relatively low temperature of 850 to 1100 ° C., so that sintering of the compact and electrode formation can be performed simultaneously. In addition, the main component ZnO crystal grain size becomes uniform by low-temperature firing, and the obtained varistor has the effect of reducing the varistor voltage variation (standard deviation σ) and improving the yield.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
The invention according to claim 1 of the present invention relates to a composition containing ZnO as a main component and at least Bi 2 O 3 and Sb 2 O 3 as subcomponents, and further comprising a solution of a Mn compound in which Mn is reduced to 0 relative to ZnO. This is a varistor using a varistor element obtained by firing a molded body of a material added in a range of 0.01 to 1.0 at% at a temperature of 850 to 1100 ° C. The Mn compound added in the form of a solution is thermally decomposed at a temperature near 600 ° C. in the firing process of the molded body to form MnO 2 having high chemical activity, which easily reacts with Bi 2 O 3 in the composition and has a relatively low activity. A liquid phase is generated at a temperature, and the liquid phase reacts with ZnO to lower the sintering start temperature. Therefore, sintering is possible even at a temperature of 850 to 1100 ° C. lower than the conventional firing temperature, and In addition, the sintering of the compact and the electrode formation can be performed simultaneously, and the sintering at a low temperature allows the main component ZnO crystal grain size to grow to a uniform size, thereby reducing the variation in the varistor voltage and reducing the characteristic yield. It also has the effect of improving
[0007]
The invention according to
[0008]
The invention according to claim 3 of the present invention is the varistor according to claim 1, wherein Ag or an Ag-Pd compound is used as an electrode metal component. It defines an electrode metal component that can be integrally sintered with the varistor molded body in a temperature range of 850 to 1100 ° C.
[0009]
The invention described in claim 4 of the present invention is characterized in that after forming and applying an electrode paste containing a metal component having a melting point of 850 ° C. or more as a main component on both surfaces of the molded body, the molded body and the electrode are integrally fired. A method for manufacturing a varistor according to claim 1. As described in the preceding section, since the varistor composition of the present invention can be sintered at a low temperature of 850 to 1100 ° C., an electrode paste composed of a metal component having a melting point of 850 ° C. or more is applied to the molded body, and Sintering and electrode formation can be performed simultaneously.
[0010]
Hereinafter, an embodiment of the present invention will be described.
(Embodiment 1)
FIG. 1 shows a varistor according to an embodiment of the present invention. In FIG. 1, 1 is a varistor element, and 2a and 2b are electrodes.
[0011]
A method for manufacturing this varistor will be described below. First, the ZnO main component, 0.5 mol% of Bi 2 O 3 as an auxiliary component, Sb 2 O 3 and 0.25mol%, Co 2 O 3 and 0.5 mol%, the Al 2 O 3 0.005mol% A Mn (NO 3 ) 2 solution is further added to and mixed with the composition so that Mn is in a range of 0.005 to 1.5 at% with respect to ZnO, followed by dehydration drying. Granulation is performed by adding polyvinyl alcohol to each of the obtained varistor materials.
[0012]
Next, each granulated powder was molded at a molding pressure of 80 MPa / cm 2 into a disk having a diameter of 15 mm and a thickness of 1.5 mm, and an electrode paste containing Ag as a main component was screened on both surfaces of each molded body. The
[0013]
The varistor voltage when a current of 1 mA and 10 μA was passed through each of the obtained varistors was measured, and a varistor voltage per 1 mm thickness (V 1 mA / mm) and a voltage nonlinear coefficient (α) were calculated. The results are shown in (Table 1). Note that the voltage nonlinear coefficient α is obtained from (Equation 1).
[0014]
[Table 1]
(Equation 1)
As shown in Table 1, Mn (NO 3 ) 2 in the form of a solution in which Mn was added in the range of 0.01 to 1.0 at% with respect to ZnO was found to have a variation in varistor voltage (standard deviation σ). ) Is small and the voltage non-linearity is high. On the other hand, when the added amount of Mn is less than 0.01 at%, the varistor voltage is too high and is not practical, and the varistor voltage varies greatly. When the amount of Mn is more than 1.0 at%, the voltage non-linearity becomes extremely small. On the other hand, when MnO 2 was used instead of Mn (NO 3 ) 2, the varistor voltage was high and the variation in varistor voltage was large despite the same amount of Mn added.
[0017]
In addition, of the above compositions, the composition in which Mn was added in an amount of 0.5 at% was fired at 800 to 1000 ° C. for 30 minutes, and the firing shrinkage at each temperature was measured. The results are shown in FIG. Was.
[0018]
As is clear from FIG. 2, when Mn is added in the form of a solution of Mn (NO 3 ) 2 , firing shrinkage of the molded body starts at a lower temperature than when Mn is added in the form of MnO 2 in a powder state. It can be seen that the sintering reaction ends at a relatively low temperature. This is because Mn (NO 3 ) 2 added in the form of a solution is thermally decomposed at a temperature around 600 ° C. during the sintering process of the molded body, and MnO 2 fine particles having high chemical activity are generated. This reacts with Bi 2 O 3 in the composition to form a liquid phase at relatively low temperatures. It is considered that this liquid phase reacts with ZnO and lowers the sintering start temperature. Therefore, it shows that the sintering of the compact can be completed even at a temperature of 850 to 1100 ° C. lower than the conventional firing temperature.
[0019]
From the results, when the addition amount of Mn in the present embodiment is less than 0.01 at%, the amount of MnO 2 having high activity is small, and the liquid phase generated by MnO 2 and Bi 2 O 3 is small, At 950 ° C., the effect of promoting the crystal grain growth of ZnO becomes insufficient, which indicates that the varistor sintered body is in a state of powder sintering. However, if it is more than 1.0 at%, it is not clear why the voltage non-linearity becomes small because the analysis is not sufficiently performed.
[0020]
From the above results, at a firing temperature of 1100 ° C. or less, in order to obtain a sintered body having a large voltage nonlinear coefficient and a small variation in varistor voltage, Mn must be contained in the form of a Mn (NO 3 ) 2 solution in the form of 0.01%. It is understood that it is necessary to add in the range of ~ 1.0 at%. In this embodiment, Mn (NO 3 ) 2 was added in the form of a solution, but it has been confirmed that the same effect can be obtained by using MnSO 4 solution.
[0021]
(Embodiment 2)
First, using a granulated powder prepared by adding Mn (0.1 at%) to ZnO in the form of Mn (NO 3 ) 2 prepared in Embodiment 1, a diameter of 15 mm and a thickness of 1 mm under a molding pressure of 80 MPa / cm 2 . It was formed into a 5 mm disk shape.
[0022]
Next,
[0023]
Next, sintering of the compact and formation of the
[0024]
[Table 2]
As shown in (Table 2), when the metal component of the
[0026]
In any case, at a temperature lower than 850 ° C., the formation state of the
[0027]
In this embodiment, Ag and the Ag-Pd compound are used as the electrode metal components. However, a metal that does not melt in the firing temperature range of the varistor molded body of the present invention and does not react with the constituent elements in the varistor material component is used. If so, other metals may be used.
[0028]
【The invention's effect】
As described above, according to the present invention, a varistor composition containing at least Bi 2 O 3 and Sb 2 O 3 as subcomponents in ZnO as a main component, and a Mn compound in the form of a solution containing Mn in an amount of 0.01 to 1 with respect to ZnO. When the varistor material is added in the range of 0.0 at%, the Mn compound added in the form of a solution is decomposed at a temperature of about 600 ° C. in the firing process to form highly active MnO 2 fine particles, which are Bi in the component. It reacts with 2 O 3 to produce a liquid phase at a relatively low temperature, which has the effect of lowering the sintering start temperature. Therefore, at a firing temperature of 850 to 1100 ° C., it is possible to simultaneously perform sintering of the compact and electrode formation. In addition, the obtained fired body is composed of uniform ZnO crystal grains, has a large voltage non-linearity, has a small variation in varistor voltage, and has an improved characteristic yield.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a varistor obtained by a method for manufacturing a varistor according to one embodiment of the present invention.
1 Varistor
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25825398A JP3551780B2 (en) | 1998-09-11 | 1998-09-11 | Varistor and manufacturing method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| JP25825398A JP3551780B2 (en) | 1998-09-11 | 1998-09-11 | Varistor and manufacturing method thereof |
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| JP2000091107A JP2000091107A (en) | 2000-03-31 |
| JP3551780B2 true JP3551780B2 (en) | 2004-08-11 |
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| JP25825398A Expired - Lifetime JP3551780B2 (en) | 1998-09-11 | 1998-09-11 | Varistor and manufacturing method thereof |
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| JP (1) | JP3551780B2 (en) |
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