JP6801407B2

JP6801407B2 - Surge protective element and its manufacturing method

Info

Publication number: JP6801407B2
Application number: JP2016233847A
Authority: JP
Inventors: 黛　良享; 良享黛; 良市杉本; 酒井　信智; 信智酒井
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2016-12-01
Filing date: 2016-12-01
Publication date: 2020-12-16
Anticipated expiration: 2036-12-01
Also published as: JP2018092754A

Description

本発明は、落雷等で発生するサージから様々な機器を保護し、事故を未然に防ぐのに使用するサージ防護素子及びその製造方法に関する。 The present invention relates to a surge protective element used to protect various devices from surges generated by lightning strikes and the like and to prevent accidents, and a method for manufacturing the same.

電話機、ファクシミリ、モデム等の通信機器用の電子機器が通信線との接続する部分、電源線、アンテナ或いはＣＲＴ、液晶テレビおよびプラズマテレビ等の画像表示駆動回路等、雷サージや静電気等の異常電圧（サージ電圧）による電撃を受けやすい部分には、異常電圧によって電子機器やこの機器を搭載するプリント基板の熱的損傷又は発火等による破壊を防止するために、サージ防護素子が接続されている。 Abnormal voltage such as lightning surge and static electricity in parts where electronic devices for communication devices such as telephones, facsimiles and modems connect to communication lines, power lines, antennas or CRTs, image display drive circuits such as LCD TVs and plasma TVs, etc. A surge protective element is connected to a portion susceptible to electric shock due to (surge voltage) in order to prevent thermal damage or ignition of an electronic device or a printed circuit board on which the device is mounted due to an abnormal voltage.

従来、例えば特許文献１に示すように、一対の封止電極から対向状態に突出した一対の突出電極部を備え、絶縁性管の内面に放電補助部が形成されたアレスタ型のサージ防護素子が記載されている。このサージ防護素子では、一対の突出電極部の対向面に略直方体状の多数の穴部が略マトリクス状に配置形成され、各穴部内面に、イオン源材料として五酸化バナジウム−酸化亜鉛−酸化バリウム−二酸化テルル系ガラスが含有された被膜が形成されている。 Conventionally, as shown in Patent Document 1, for example, an arrester-type surge protective element having a pair of protruding electrode portions protruding from a pair of sealing electrodes in a facing state and a discharge assisting portion formed on the inner surface of an insulating tube has been used. Have been described. In this surge protective element, a large number of substantially rectangular parallelepiped holes are arranged and formed in a substantially matrix shape on the facing surfaces of the pair of protruding electrode portions, and vanadium pentoxide-zinc oxide-oxidation as an ion source material is formed on the inner surface of each hole portion. A film containing barium-tellurium dioxide glass is formed.

このイオン源材料は、放電電圧の制御と電極保護の目的のために突出電極部の対向面に設けられている。また、上記多数の穴部は、イオン源材料の保持と塗布の均一化とを得るための凹凸として形成されている。すなわち、イオン源材料を突出電極部の対向面に形成した凹凸に付着させ、アンカー効果を利用して脱落を防止している。 This ion source material is provided on the facing surface of the protruding electrode portion for the purpose of controlling the discharge voltage and protecting the electrode. Further, the large number of holes are formed as irregularities for retaining the ion source material and making the coating uniform. That is, the ion source material is attached to the unevenness formed on the facing surface of the protruding electrode portion, and the anchor effect is used to prevent the ion source material from falling off.

実用新案登録第３１５１０６９号公報Utility Model Registration No. 3151069

上記従来の技術には、以下の課題が残されている。
すなわち、イオン源材料を突出電極部の対向面の凹凸に付着させているが、アーク耐性を向上させるために、さらに高い付着力でイオン源材料を形成することが要求されている。また、イオン源材料は、結晶化及び電極への付着力向上の目的で熱処理を施す必要があり、熱処理時にイオン源材料の塊が大きいほど、熱処理時に熱分解による脱水反応により蒸気等のガスが発生し、イオン源材料の膨れが生じる。この膨れの影響により、イオン源材料の密度が低下し、結晶化度が低下してしまう問題があった。このように結晶化度が低い場合、繰り返しサージによるイオン源材料の脱落や飛散、及びアーク放電に対する耐性を低下させる原因になっていた。また、熱処理時の温度を高く設定するほど結晶化度は向上するが、一度膨れてしまうと、密度が低下してイオン源材料の結晶化を阻害してしまう不都合があった。 The following problems remain in the above-mentioned conventional technique.
That is, the ion source material is adhered to the unevenness of the facing surface of the protruding electrode portion, but in order to improve the arc resistance, it is required to form the ion source material with a higher adhesive force. In addition, the ion source material needs to be heat-treated for the purpose of crystallization and improvement of adhesion to the electrode. The larger the mass of the ion source material during the heat treatment, the more gas such as steam is generated by the dehydration reaction due to thermal decomposition during the heat treatment. Occurs, causing swelling of the ion source material. Due to the influence of this swelling, there is a problem that the density of the ion source material is lowered and the crystallinity is lowered. When the crystallinity is low as described above, it causes the ion source material to fall off or scatter due to repeated surges, and to reduce the resistance to arc discharge. Further, the higher the temperature during the heat treatment, the higher the crystallinity, but once the swelling occurs, the density decreases and the crystallization of the ion source material is hindered.

本発明は、前述の課題に鑑みてなされたもので、イオン源材料の膨れを抑制可能であり、高い付着力と結晶化度とを得ることができるサージ防護素子及びその製造方法を提供することを目的とする。 The present invention has been made in view of the above-mentioned problems, and provides a surge protective element capable of suppressing swelling of an ion source material, and capable of obtaining high adhesive force and crystallinity, and a method for manufacturing the same. With the goal.

本発明は、前記課題を解決するために以下の構成を採用した。すなわち、第１の発明に係るサージ防護素子は、絶縁性管と、前記絶縁性管の両端開口部を閉塞して内部に放電制御ガスを封止する一対の封止電極とを備え、一対の前記封止電極が、内方に突出し互いに対向した一対の突出電極部を有し、一対の前記突出電極部の対向面に多孔質金属層が設けられていると共に、前記封止電極の材料よりも電子放出特性の高い材料で形成された放電活性層が、前記多孔質金属層内に少なくとも一部が入り込んだ状態で前記多孔質金属層の表面に設けられていることを特徴とする。 The present invention has adopted the following configuration in order to solve the above problems. That is, the surge protection element according to the first invention includes an insulating tube and a pair of sealing electrodes that close the openings at both ends of the insulating tube to seal the discharge control gas inside. The sealing electrode has a pair of protruding electrode portions protruding inward and facing each other, a porous metal layer is provided on the facing surfaces of the pair of protruding electrode portions, and the material of the sealing electrode is used. Also characterized in that, a discharge active layer formed of a material having high electron emission characteristics is provided on the surface of the porous metal layer in a state where at least a part thereof is embedded in the porous metal layer.

このサージ防護素子では、一対の突出電極部の対向面に多孔質金属層が設けられていると共に、封止電極の材料よりも電子放出特性の高い材料で形成された放電活性層が、多孔質金属層内に少なくとも一部が入り込んだ状態で多孔質金属層の表面に設けられているので、放電活性層が多孔質金属層中の空隙（気孔）に入り込んで従来より高い付着力が得られる。また、多孔質金属層に付着させたイオン源材料を熱処理して放電活性層を形成する際に、イオン源材料が多孔質金属層中の空隙内に均一的に微細分散しており、発生する蒸気等が空隙を介して外部に抜けるため、膨れの発生が抑制され、放電活性層の結晶化度が向上する。 In this surge protection element, a porous metal layer is provided on the facing surfaces of the pair of protruding electrode portions, and the discharge active layer formed of a material having higher electron emission characteristics than the material of the sealing electrode is porous. Since at least a part of the metal layer is provided on the surface of the porous metal layer, the discharge active layer enters the voids (pores) in the porous metal layer, and a higher adhesive force than before can be obtained. .. Further, when the ion source material adhered to the porous metal layer is heat-treated to form a discharge active layer, the ion source material is uniformly finely dispersed in the voids in the porous metal layer, which is generated. Since steam or the like escapes to the outside through the voids, the occurrence of swelling is suppressed and the degree of crystallization of the discharge active layer is improved.

第２の発明に係るサージ防護素子は、第１の発明において、前記多孔質金属層が、タングステンで形成されていることを特徴とする。
すなわち、このサージ防護素子では、多孔質金属層が、タングステンで形成されているので、高融点金属であるタングステンによってアーク耐性がさらに向上する。 The surge protective element according to the second invention is characterized in that, in the first invention, the porous metal layer is formed of tungsten.
That is, in this surge protective element, since the porous metal layer is formed of tungsten, the arc resistance is further improved by tungsten, which is a refractory metal.

第３の発明に係るサージ防護素子は、第１又は第２の発明において、前記多孔質金属層が、前記突出電極部の外周面にも設けられていることを特徴とする。
すなわち、このサージ防護素子では、多孔質金属層が、突出電極部の外周面にも設けられているので、突出電極部の外周面が多孔質金属層で保護され、さらにアーク耐性が向上する。 The surge protective element according to the third invention is characterized in that, in the first or second invention, the porous metal layer is also provided on the outer peripheral surface of the protruding electrode portion.
That is, in this surge protective element, since the porous metal layer is also provided on the outer peripheral surface of the protruding electrode portion, the outer peripheral surface of the protruding electrode portion is protected by the porous metal layer, and the arc resistance is further improved.

第４の発明に係るサージ防護素子は、第１から第３の発明のいずれかにおいて、前記多孔質金属層が、前記突出電極部に貼り付けられた多孔質金属板であることを特徴とする。
すなわち、このサージ防護素子では、多孔質金属層が、突出電極部に貼り付けられた多孔質金属板であるので、多孔質金属板を別に作製して熱溶着やろう材等によって貼り付けるだけで容易に多孔質金属層を形成することができる。また、多孔質金属層の厚さや形状、及び空隙の気孔率等も任意に設定可能になる。 The surge protective element according to the fourth invention is characterized in that, in any one of the first to third inventions, the porous metal layer is a porous metal plate attached to the protruding electrode portion. ..
That is, in this surge protection element, since the porous metal layer is a porous metal plate attached to the protruding electrode portion, it is only necessary to separately prepare the porous metal plate and attach it by heat welding or a brazing material or the like. A porous metal layer can be easily formed. Further, the thickness and shape of the porous metal layer, the porosity of the voids, and the like can be arbitrarily set.

第５の発明に係るサージ防護素子は、第４の発明において、前記多孔質金属板が、発泡金属体で形成されていることを特徴とする。
すなわち、このサージ防護素子では、多孔質金属板が、発泡金属体で形成されているので、気孔を多数含んだ発泡金属体により高い気孔率の多孔質金属層が得られる。 The surge protective element according to the fifth invention is characterized in that, in the fourth invention, the porous metal plate is formed of a foamed metal body.
That is, in this surge protection element, since the porous metal plate is formed of a foamed metal body, a porous metal layer having a high porosity can be obtained by the foamed metal body containing a large number of pores.

第６の発明に係るサージ防護素子は、第４の発明において、前記多孔質金属板が、金属繊維を焼結した金属繊維焼結体で形成されていることを特徴とする。
すなわち、このサージ防護素子では、多孔質金属板が、金属繊維を焼結した金属繊維焼結体で形成されているので、金属繊維間に多数の空隙を有した緻密な多孔質金属層が得られる。 The surge protection element according to the sixth invention is characterized in that, in the fourth invention, the porous metal plate is formed of a metal fiber sintered body obtained by sintering metal fibers.
That is, in this surge protection element, since the porous metal plate is formed of a metal fiber sintered body obtained by sintering metal fibers, a dense porous metal layer having a large number of voids between the metal fibers can be obtained. Be done.

第７の発明に係るサージ防護素子は、第４の発明において、前記多孔質金属板が、金属粉末を焼結した焼結体であって内部に複数の空隙を有した金属粉末焼結体で形成されていることを特徴とする。
すなわち、このサージ防護素子では、多孔質金属板が、金属粉末を焼結した焼結体であって内部に複数の空隙を有した金属粉末焼結体で形成されているので、金属粉末間に多数の空隙を有した多孔質金属層が得られる。 The surge protection element according to the seventh invention is a metal powder sintered body in which the porous metal plate is a sintered body obtained by sintering metal powder and has a plurality of voids inside in the fourth invention. It is characterized by being formed.
That is, in this surge protection element, since the porous metal plate is a sintered body obtained by sintering metal powder and is formed of a metal powder sintered body having a plurality of voids inside, there is a gap between the metal powders. A porous metal layer having a large number of voids can be obtained.

第８の発明に係るサージ防護素子の製造方法は、第１から第７の発明のいずれかのサージ防護素子を製造する方法であって、前記突出電極部の対向面に前記多孔質金属層を形成する多孔質金属層形成工程と、前記多孔質金属層の表面に前記放電活性層を形成する放電活性層形成工程とを有し、前記放電活性層形成工程で、イオン源材料を前記多孔質金属層に付着させる工程と、前記イオン源材料を熱処理して前記放電活性層を形成する工程とを有していることを特徴とする。
すなわち、このサージ防護素子の製造方法では、放電活性層形成工程で、イオン源材料を多孔質金属層に付着させる工程と、前記封止電極の材料よりも電子放出特性の高い材料を含むイオン源材料を熱処理して放電活性層を形成する工程とを有しているので、イオン源材料が多孔質金属層中の空隙内に均一的に微細分散し、熱処理時に発生する蒸気等が空隙を介して外部に抜けるため、膨れの発生が抑制され、放電活性層の結晶化度が向上する。 The method for manufacturing a surge protection element according to an eighth invention is a method for manufacturing a surge protection element according to any one of the first to seventh inventions, wherein the porous metal layer is formed on a facing surface of the protruding electrode portion. It has a step of forming a porous metal layer to be formed and a step of forming a discharge active layer on the surface of the porous metal layer, and in the step of forming the discharge active layer, the ion source material is made of the porous material. It is characterized by having a step of adhering to the metal layer and a step of heat-treating the ion source material to form the discharge active layer.
That is, in this method of manufacturing a surge protection element, in the discharge active layer forming step, an ion source including a step of adhering an ion source material to a porous metal layer and a material having higher electron emission characteristics than the material of the sealing electrode. Since it has a step of heat-treating the material to form a discharge active layer, the ion source material is uniformly finely dispersed in the voids in the porous metal layer, and steam or the like generated during the heat treatment passes through the voids. As a result, the occurrence of swelling is suppressed and the degree of crystallization of the discharge active layer is improved.

第９の発明に係るサージ防護素子の製造方法は、第１から第３の発明のいずれかのサージ防護素子を製造する方法であって、前記突出電極部の対向面に前記多孔質金属層を形成する多孔質金属層形成工程と、前記多孔質金属層の表面に前記放電活性層を形成する放電活性層形成工程とを有し、前記放電活性層形成工程で、前記封止電極の材料よりも電子放出特性の高い材料を含むイオン源材料を前記多孔質金属層に付着させる工程と、前記イオン源材料を熱処理して前記放電活性層を形成する工程とを有し、前記多孔質金属層形成工程で、前記突出電極部の対向面に金属溶湯を溶射して前記多孔質金属層を形成することを特徴とする。
すなわち、このサージ防護素子の製造方法では、多孔質金属層形成工程で、突出電極部の対向面に金属溶湯を溶射して多孔質金属層を形成するので、溶射によって突出電極部の対向面に付着した金属内に多数の空隙（気孔）が生じることで、容易に多孔質金属層を得ることができる。 The method for manufacturing a surge protection element according to a ninth invention is a method for manufacturing a surge protection element according to any one of the first to third inventions, wherein the porous metal layer is formed on a facing surface of the protruding electrode portion. It has a porous metal layer forming step to be formed and a discharge active layer forming step of forming the discharge active layer on the surface of the porous metal layer, and in the discharge active layer forming step, from the material of the sealing electrode. Also has a step of adhering an ion source material containing a material having high electron emission characteristics to the porous metal layer and a step of heat-treating the ion source material to form the discharge active layer, and the porous metal layer. In the forming step, the molten metal is sprayed onto the facing surface of the protruding electrode portion to form the porous metal layer.
That is, in this method of manufacturing the surge protection element, in the porous metal layer forming step, the molten metal is sprayed on the facing surface of the protruding electrode portion to form the porous metal layer, so that the facing surface of the protruding electrode portion is formed by spraying. A porous metal layer can be easily obtained by forming a large number of voids (pores) in the adhered metal.

本発明によれば、以下の効果を奏する。
すなわち、本発明に係るサージ防護素子及びその製造方法によれば、一対の突出電極部の対向面に多孔質金属層が設けられると共に、封止電極の材料よりも電子放出特性の高い材料で形成された放電活性層が、多孔質金属層内に少なくとも一部が入り込んだ状態で多孔質金属層の表面に設けられているので、放電活性層の高い付着力及び結晶化度が得られると共に、熱処理時の膨れの発生が抑制される。
したがって、本発明に係るサージ防護素子では、アーク放電に対する耐性が向上し、サージ耐量特性が向上すると共に安定した放電が可能になる。その結果、放電開始電圧の変動幅を小さくできると共に、電極損傷が低減でき、素子の高寿命化（作動可能なサージ印加数の増大）に寄与することができる。
特に、本発明に係るサージ防護素子は、大電流サージ耐性が要求されるインフラ用（鉄道関連、再生エネルギー関連（太陽電池、風力発電等））の電源及び通信設備に好適である。また、サージ耐量が向上しているため、素子の小型化も可能になり、小型電子機器及び実装基板への応用も可能になる。 According to the present invention, the following effects are obtained.
That is, according to the surge protection element and the manufacturing method thereof according to the present invention, a porous metal layer is provided on the facing surfaces of the pair of protruding electrode portions, and the material is formed of a material having higher electron emission characteristics than the material of the sealing electrode. Since the discharged discharge active layer is provided on the surface of the porous metal layer in a state where at least a part thereof has entered the porous metal layer, high adhesion and crystallization degree of the discharge active layer can be obtained, and at the same time, the discharge active layer can be obtained. The occurrence of swelling during heat treatment is suppressed.
Therefore, in the surge protection element according to the present invention, the resistance to arc discharge is improved, the surge resistance characteristic is improved, and stable discharge is possible. As a result, the fluctuation range of the discharge start voltage can be reduced, the electrode damage can be reduced, and the life of the device can be extended (the number of operable surges applied can be increased).
In particular, the surge protective element according to the present invention is suitable for power sources and communication equipment for infrastructures (railroad-related, renewable energy-related (solar cells, wind power generation, etc.)) that require large current surge resistance. Further, since the surge resistance is improved, the element can be miniaturized, and it can be applied to small electronic devices and mounting boards.

本発明に係るサージ防護素子及びその製造方法の第１実施形態を示す軸方向の断面図である。It is sectional drawing in the axial direction which shows 1st Embodiment of the surge protection element which concerns on this invention and the manufacturing method thereof. 第１実施形態において、要部を示す拡大断面図である。In the first embodiment, it is an enlarged cross-sectional view which shows the main part. 図１のＡ−Ａ線矢視断面図である。FIG. 1 is a cross-sectional view taken along the line AA of FIG. 本発明に係るサージ防護素子及びその製造方法の第２実施形態を示す軸方向の断面図である。It is sectional drawing in the axial direction which shows the 2nd Embodiment of the surge protection element which concerns on this invention and the manufacturing method thereof. 本発明に係るサージ防護素子及びその製造方法の第３実施形態を示す軸方向の断面図である。It is sectional drawing in the axial direction which shows the 3rd Embodiment of the surge protection element which concerns on this invention and the manufacturing method thereof. 本発明に係るサージ防護素子及びその製造方法の第４実施形態を示す軸方向の断面図である。It is sectional drawing in the axial direction which shows 4th Embodiment of the surge protection element which concerns on this invention and the manufacturing method thereof.

以下、本発明に係るサージ防護素子及びその製造方法の第１実施形態を、図１から図３を参照しながら説明する。なお、以下の説明に用いる各図面では、各部材を認識可能又は認識容易な大きさとするために縮尺を適宜変更している。 Hereinafter, the first embodiment of the surge protective element and the method for manufacturing the surge protective element according to the present invention will be described with reference to FIGS. 1 to 3. In each drawing used in the following description, the scale is appropriately changed in order to make each member recognizable or easily recognizable.

本実施形態のサージ防護素子１は、図１に示すように、絶縁性管２と、絶縁性管２の両端開口部を閉塞して内部に放電制御ガスを封止する一対の封止電極３とを備えている。
上記一対の封止電極３は、内方に突出し互いに対向した一対の突出電極部５を有している。
上記一対の突出電極部５の対向面５ａには、図２に示すように、多孔質金属層８が設けられていると共に、封止電極３の材料よりも電子放出特性の高い材料で形成された放電活性層９が、多孔質金属層８内に少なくとも一部が入り込んだ状態で多孔質金属層８の表面に設けられている。すなわち、放電活性層９が、多孔質金属層８内の空隙に浸透した状態で形成されている。 As shown in FIG. 1, the surge protection element 1 of the present embodiment is a pair of sealing electrodes 3 that close the insulating tube 2 and the openings at both ends of the insulating tube 2 to seal the discharge control gas inside. And have.
The pair of sealing electrodes 3 has a pair of protruding electrode portions 5 that project inward and face each other.
As shown in FIG. 2, the facing surfaces 5a of the pair of protruding electrode portions 5 are provided with a porous metal layer 8 and are formed of a material having higher electron emission characteristics than the material of the sealing electrode 3. The discharge active layer 9 is provided on the surface of the porous metal layer 8 in a state where at least a part thereof has entered the porous metal layer 8. That is, the discharge active layer 9 is formed in a state of permeating into the voids in the porous metal layer 8.

上記多孔質金属層８は、例えばタングステンで形成されており、タングステンの金属溶湯を突出電極部５に溶射することによって形成されている。
また、多孔質金属層８は、突出電極部５の外周面にも設けられている。
なお、本実施形態のサージ防護素子１は、絶縁性管２の内周面にイオン源材料で形成された放電補助部４を備えている。 The porous metal layer 8 is formed of, for example, tungsten, and is formed by spraying a molten metal of tungsten onto the protruding electrode portion 5.
Further, the porous metal layer 8 is also provided on the outer peripheral surface of the protruding electrode portion 5.
The surge protection element 1 of the present embodiment includes a discharge assisting portion 4 formed of an ion source material on the inner peripheral surface of the insulating tube 2.

上記放電活性層９は、イオン源材料として、例えばＳｉ，Ｏを主成分元素とし、Ｎａ，Ｃｓ，Ｃのうちの少なくとも一つを含んでいる。この放電活性層９は、例えばケイ酸ナトリウム溶液に炭酸セシウム粉末を加えて前駆体を作製し、この前駆体を多孔質金属層８に塗布して付着させた後、前駆体に対してケイ酸ナトリウムが軟化する温度以上かつ炭酸セシウムが融解及び分解する温度以上の温度で熱処理を行うことで作製される。
なお、本実施形態では、放電活性層９を対向面５ａ上の多孔質金属層８における中央部に形成している。 The discharge active layer 9 contains, for example, Si and O as main component elements as an ion source material, and contains at least one of Na, Cs, and C. In the discharge active layer 9, for example, cesium carbonate powder is added to a sodium silicate solution to prepare a precursor, and the precursor is applied to the porous metal layer 8 and adhered to the precursor, and then silicate is attached to the precursor. It is produced by performing heat treatment at a temperature equal to or higher than the temperature at which sodium softens and the temperature at which cesium carbonate melts and decomposes.
In this embodiment, the discharge active layer 9 is formed at the central portion of the porous metal layer 8 on the facing surface 5a.

上記放電補助部４は、導電性材料であって、例えば炭素材で形成された放電補助部である。
なお、本実施形態では、放電補助部４は、絶縁性管２の内周面に軸線Ｃに沿って直線状に形成されている。
また、図１では、放電補助部４を軸線Ｃに沿った１本のみ図示しているが、周方向に互いに間隔を空けて複数本形成しても構わない。 The discharge assisting portion 4 is a conductive material, for example, a discharge assisting portion made of a carbon material.
In the present embodiment, the discharge assisting portion 4 is formed linearly along the axis C on the inner peripheral surface of the insulating tube 2.
Further, in FIG. 1, only one discharge assisting portion 4 is shown along the axis C, but a plurality of discharge assisting portions 4 may be formed at intervals in the circumferential direction.

上記封止電極３は、例えば４２アロイ（Ｆｅ：５８ｗｔ％、Ｎｉ：４２ｗｔ％）やＣｕ等で構成されている。
封止電極３は、絶縁性管２の両端開口部に導電性融着材（図示略）により加熱処理によって密着状態に固定されている円板状のフランジ部７を有している。このフランジ部７の内側に、内方に突出していると共に絶縁性管２の内径よりも外径の小さな円柱状の突出電極部５が一体に設けられている。 The sealing electrode 3 is made of, for example, 42 alloy (Fe: 58 wt%, Ni: 42 wt%), Cu, or the like.
The sealing electrode 3 has a disc-shaped flange portion 7 fixed to the openings at both ends of the insulating tube 2 in a close contact state by a heat treatment with a conductive fusion material (not shown). Inside the flange portion 7, a columnar protruding electrode portion 5 that protrudes inward and has an outer diameter smaller than the inner diameter of the insulating tube 2 is integrally provided.

上記絶縁性管２は、アルミナなどの結晶性セラミックス材である。なお、絶縁性管２は、鉛ガラス等のガラス管で形成しても構わない。
上記導電性融着材は、例えばＡｇを含むろう材としてＡｇ−Ｃｕろう材で形成されている。
上記絶縁性管２内に封入される放電制御ガスは、不活性ガス等であって、例えばＨｅ，Ａｒ，Ｎｅ，Ｘｅ，Ｋｒ，ＳＦ_６，ＣＯ_２，Ｃ_３Ｆ_８，Ｃ_２Ｆ_６，ＣＦ_４，Ｈ_２，大気等及びこれらの混合ガスが採用される。 The insulating tube 2 is a crystalline ceramic material such as alumina. The insulating tube 2 may be formed of a glass tube such as lead glass.
The conductive fusion material is formed of Ag-Cu brazing material as a brazing material containing Ag, for example.
The discharge control gas sealed in the insulating tube 2 is an inert gas or the like, for example, He, Ar, Ne, Xe, Kr, SF ₆ , CO ₂ , C ₃ F ₈ , C ₂ F ₆ , CF ₄ , H ₂ , air, etc. and a mixed gas thereof are adopted.

上記多孔質金属層８は、多数の空隙（気孔）を有したポーラスな金属層であり、例えば空隙間隔が１００ｎｍ〜３００μｍとされる。また、多孔質金属層８の気孔率は、５０〜９８％とされる。
なお、上記気孔率が９８％を超えると、構造体強度が低くなり、サージ（アーク放電）により表面が破損し易くなる。 The porous metal layer 8 is a porous metal layer having a large number of voids (pores), and the gap between the voids is, for example, 100 nm to 300 μm. The porosity of the porous metal layer 8 is 50 to 98%.
If the porosity exceeds 98%, the strength of the structure becomes low, and the surface is easily damaged by surge (arc discharge).

このサージ防護素子１を製造する方法は、突出電極部５の対向面５ａに多孔質金属層８を形成する多孔質金属層形成工程と、多孔質金属層８の表面に放電活性層９を形成する放電活性層形成工程とを有している。
上記放電活性層形成工程では、封止電極３の材料よりも電子放出特性の高い材料を含むイオン源材料を多孔質金属層８に付着させる工程と、イオン源材料を熱処理して放電活性層９を形成する工程とを有している。
さらに、多孔質金属層形成工程において、突出電極部５の対向面５ａに金属溶湯を溶射して多孔質金属層８を形成する。なお、溶射は、プラズマ溶射が採用され、金属溶湯としては、タングステンの溶湯が用いられる。 The method for manufacturing the surge protection element 1 includes a step of forming a porous metal layer 8 on the facing surface 5a of the protruding electrode portion 5 and a process of forming a discharge active layer 9 on the surface of the porous metal layer 8. It has a discharge active layer forming step.
In the discharge active layer forming step, an ion source material containing a material having higher electron emission characteristics than the material of the sealing electrode 3 is attached to the porous metal layer 8, and the ion source material is heat-treated to form the discharge active layer 9. Has a step of forming.
Further, in the porous metal layer forming step, the molten metal is sprayed onto the facing surface 5a of the protruding electrode portion 5 to form the porous metal layer 8. Plasma spraying is adopted as the thermal spraying, and tungsten spraying is used as the metal spraying.

このように作製したサージ防護素子１では、過電圧又は過電流が侵入すると、まず放電補助部４と突出電極部５又は多孔質金属層８との間で初期放電が行われ、この初期放電をきっかけに、さらに放電が進展して、一方の突出電極部５の対向面５ａの多孔質金属層８各所から他方の突出電極部５側へアーク放電が行われる。 In the surge protection element 1 produced in this way, when an overvoltage or an overcurrent invades, an initial discharge is first performed between the discharge assisting portion 4 and the protruding electrode portion 5 or the porous metal layer 8, and this initial discharge is triggered. Further, the discharge further progresses, and an arc discharge is performed from each part of the porous metal layer 8 on the facing surface 5a of the one protruding electrode portion 5 to the other protruding electrode portion 5 side.

このように本実施形態のサージ防護素子１では、一対の突出電極部５の対向面５ａに多孔質金属層８が設けられていると共に、封止電極３の材料よりも電子放出特性の高い材料で形成された放電活性層９が、多孔質金属層８内に少なくとも一部が入り込んだ状態で多孔質金属層８の表面に設けられているので、放電活性層９が多孔質金属層８中の空隙（気孔）に入り込んで従来より高い付着力が得られる。 As described above, in the surge protection element 1 of the present embodiment, the porous metal layer 8 is provided on the facing surfaces 5a of the pair of protruding electrode portions 5, and the material has higher electron discharge characteristics than the material of the sealing electrode 3. Since the discharge active layer 9 formed in the above is provided on the surface of the porous metal layer 8 with at least a part of the inside of the porous metal layer 8, the discharge active layer 9 is contained in the porous metal layer 8. It enters the voids (pores) of the above and has a higher adhesive force than before.

特に、多孔質金属層８が、タングステンで形成されることで、高融点金属であるタングステンによってアーク耐性がさらに向上する。
また、多孔質金属層８が、突出電極部５の外周面にも設けられているので、突出電極部５の外周面が多孔質金属層８で保護され、さらにアーク耐性が向上する。 In particular, since the porous metal layer 8 is formed of tungsten, the arc resistance is further improved by tungsten, which is a refractory metal.
Further, since the porous metal layer 8 is also provided on the outer peripheral surface of the protruding electrode portion 5, the outer peripheral surface of the protruding electrode portion 5 is protected by the porous metal layer 8, and the arc resistance is further improved.

また、このサージ防護素子１の製造方法では、放電活性層形成工程で、イオン源材料を多孔質金属層８に付着させる工程と、イオン源材料を熱処理して放電活性層９を形成する工程とを有しているので、イオン源材料が多孔質金属層８中の空隙内に均一的に微細分散し、熱処理時に発生する蒸気等が空隙を介して外部に抜けるため、膨れの発生が抑制され、放電活性層９の結晶化度が向上する。
さらに、多孔質金属層形成工程で、突出電極部５の対向面５ａに金属溶湯を溶射して多孔質金属層８を形成するので、溶射によって突出電極部５の対向面５ａに付着した金属内に多数の空隙（気孔）が生じることで、容易に多孔質金属層８を得ることができる。 Further, in the method for manufacturing the surge protection element 1, in the discharge active layer forming step, a step of adhering the ion source material to the porous metal layer 8 and a step of heat-treating the ion source material to form the discharge active layer 9. Therefore, the ion source material is uniformly finely dispersed in the voids in the porous metal layer 8, and steam and the like generated during the heat treatment escape to the outside through the voids, so that the occurrence of swelling is suppressed. , The degree of crystallization of the discharge active layer 9 is improved.
Further, in the porous metal layer forming step, the molten metal is sprayed onto the facing surface 5a of the protruding electrode portion 5 to form the porous metal layer 8, so that the inside of the metal adhering to the facing surface 5a of the protruding electrode portion 5 by spraying is formed. Since a large number of voids (pores) are formed in the porous metal layer 8, the porous metal layer 8 can be easily obtained.

次に、本発明に係るサージ防護素子の第２及び第３実施形態について、図４及び図５を参照して以下に説明する。なお、以下の各実施形態の説明において、上記実施形態において説明した同一の構成要素には同一の符号を付し、その説明は省略する。 Next, the second and third embodiments of the surge protection element according to the present invention will be described below with reference to FIGS. 4 and 5. In the following description of each embodiment, the same components described in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

第２実施形態と第１実施形態との異なる点は、第１実施形態では、多孔質金属層８を金属溶湯を溶射して形成しているが、第２実施形態のサージ防護素子２１では、図４に示すように、多孔質金属層２８が、突出電極部５に貼り付けられた多孔質金属板である点である。また、この多孔質金属板は、発泡金属体で形成されている。
すなわち、第２実施形態では、タングステン等の発泡金属体で形成された多孔質金属板を熱溶着又はろう材で突出電極部５に接着して多孔質金属層２８としている。
なお、第２実施形態では、突出電極部５の外周面には、多孔質金属層２８を形成していない。 The difference between the second embodiment and the first embodiment is that in the first embodiment, the porous metal layer 8 is formed by spraying a molten metal, but in the surge protection element 21 of the second embodiment, As shown in FIG. 4, the porous metal layer 28 is a porous metal plate attached to the protruding electrode portion 5. Further, this porous metal plate is formed of a foamed metal body.
That is, in the second embodiment, the porous metal plate formed of a foamed metal body such as tungsten is heat-welded or bonded to the protruding electrode portion 5 with a brazing material to form the porous metal layer 28.
In the second embodiment, the porous metal layer 28 is not formed on the outer peripheral surface of the protruding electrode portion 5.

このように第２実施形態のサージ防護素子２１では、多孔質金属層２８が、突出電極部５に貼り付けられた多孔質金属板であるので、多孔質金属板を別に作製して熱溶着やろう材等によって貼り付けるだけで容易に多孔質金属層２８を形成することができる。また、多孔質金属層２８の厚さや形状、及び空隙の気孔率等も任意に設定可能になる。
特に、多孔質金属板が、発泡金属体で形成されているので、気孔を多数含んだ発泡金属体により高い気孔率の多孔質金属層２８が得られる。 As described above, in the surge protection element 21 of the second embodiment, since the porous metal layer 28 is a porous metal plate attached to the protruding electrode portion 5, the porous metal plate is separately produced and heat-welded. The porous metal layer 28 can be easily formed only by pasting with a brazing material or the like. Further, the thickness and shape of the porous metal layer 28, the porosity of the voids, and the like can be arbitrarily set.
In particular, since the porous metal plate is made of a foamed metal body, the porous metal layer 28 having a high porosity can be obtained by the foamed metal body containing a large number of pores.

次に、第３実施形態と第２実施形態との異なる点は、第２実施形態では、多孔質金属板が、発泡金属体で形成されているのに対し、第３実施形態のサージ防護素子３１では、図５に示すように、多孔質金属板が、金属繊維を焼結した金属繊維焼結体で形成されている点である。
すなわち、第３実施形態では、タングステン等の金属繊維を焼結した金属繊維焼結体を熱溶着又はろう材で突出電極部５に接着して多孔質金属層３８を形成している。
このように第３実施形態のサージ防護素子３１では、多孔質金属板が、金属繊維を焼結した金属繊維焼結体で形成されているので、金属繊維間に多数の空隙を有した緻密な多孔質金属層３８が得られる。 Next, the difference between the third embodiment and the second embodiment is that in the second embodiment, the porous metal plate is formed of a foamed metal body, whereas the surge protection element of the third embodiment is formed. In No. 31, as shown in FIG. 5, the porous metal plate is formed of a metal fiber sintered body obtained by sintering metal fibers.
That is, in the third embodiment, a metal fiber sintered body obtained by sintering a metal fiber such as tungsten is heat-welded or bonded to a protruding electrode portion 5 with a brazing material to form a porous metal layer 38.
As described above, in the surge protection element 31 of the third embodiment, since the porous metal plate is formed of a metal fiber sintered body obtained by sintering metal fibers, it is dense with a large number of voids between the metal fibers. A porous metal layer 38 is obtained.

次に、第４実施形態と第２実施形態との異なる点は、第２実施形態では、多孔質金属板が、発泡金属体で形成されているのに対し、第４実施形態のサージ防護素子４１では、図６に示すように、多孔質金属板が、金属粉末を焼結した焼結体であって内部に複数の空隙を有した金属粉末焼結体で形成されている点である。
すなわち、第４実施形態では、タングステン等の金属粉末を例えば気孔率が３０〜９０％となるように焼結した金属粉末焼結体を、熱溶着又はろう材で突出電極部５に接着して多孔質金属層４８を形成している。
このように第４実施形態のサージ防護素子４１では、多孔質金属板が、金属粉末を焼結した焼結体であって内部に複数の空隙を有した金属粉末焼結体で形成されているので、金属粉末間に多数の空隙を有した多孔質金属層４８が得られる。 Next, the difference between the fourth embodiment and the second embodiment is that in the second embodiment, the porous metal plate is formed of a foamed metal body, whereas the surge protection element of the fourth embodiment is formed. In No. 41, as shown in FIG. 6, the porous metal plate is a sintered body obtained by sintering metal powder and is formed of a metal powder sintered body having a plurality of voids inside.
That is, in the fourth embodiment, a metal powder sintered body obtained by sintering a metal powder such as tungsten so as to have a porosity of, for example, 30 to 90% is bonded to the protruding electrode portion 5 by heat welding or a brazing material. A porous metal layer 48 is formed.
As described above, in the surge protection element 41 of the fourth embodiment, the porous metal plate is formed of a sintered body obtained by sintering metal powder and having a plurality of voids inside. Therefore, a porous metal layer 48 having a large number of voids between the metal powders can be obtained.

なお、本発明の技術範囲は上記各実施形態および上記各実施例に限定されるものではなく、本発明の趣旨を逸脱しない範囲において種々の変更を加えることが可能である。
例えば、上記各実施形態では、上述した液状のイオン源材料の前駆体を突出電極部の対向面に塗布して付着させているが、付着の方法としては、突出電極部の対向面をイオン源材料の前駆体に浸漬させることで、イオン源材料を前記対向面に付着させて構わない。 The technical scope of the present invention is not limited to the above embodiments and the above embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, in each of the above embodiments, the precursor of the above-mentioned liquid ion source material is applied to the facing surface of the protruding electrode portion and adhered, but as a method of adhesion, the facing surface of the protruding electrode portion is used as the ion source. The ion source material may be adhered to the facing surface by immersing it in the precursor of the material.

１，２１，３１，４１…サージ防護素子、２…絶縁性管、３…封止電極、４…放電補助部、５…突出電極部、５ａ…突出電極部の対向面、９…放電活性層、２８，３８，４８…多孔質金属層 1,1,1,31,41 ... Surge protective element, 2 ... Insulating tube, 3 ... Sealing electrode, 4 ... Discharge auxiliary part, 5 ... Protruding electrode part, 5a ... Facing surface of protruding electrode part, 9 ... Discharge active layer , 28, 38, 48 ... Porous metal layer

Claims

Insulating tube and
A pair of sealing electrodes for closing the openings at both ends of the insulating tube and sealing the discharge control gas inside are provided.
The pair of sealing electrodes has a pair of protruding electrode portions that project inward and face each other.
A porous metal layer is provided on the facing surfaces of the pair of protruding electrode portions, and a discharge active layer formed of a material having higher electron emission characteristics than the material of the sealing electrode is formed in the porous metal layer. It is provided on the surface of the porous metal layer in a state where at least a part of the metal layer is inserted into the porous metal layer .
A surge protective element characterized in that the discharge active layer contains Si and O as main component elements and contains at least one of Na, Cs and C.

Insulating tube and
A pair of sealing electrodes for closing the openings at both ends of the insulating tube and sealing the discharge control gas inside are provided.
The pair of sealing electrodes has a pair of protruding electrode portions that project inward and face each other.
A porous metal layer is provided on the facing surfaces of the pair of protruding electrode portions, and a discharge active layer formed of a material having higher electron emission characteristics than the material of the sealing electrode is formed in the porous metal layer. It is provided on the surface of the porous metal layer in a state where at least a part of the metal layer is inserted into the porous metal layer.
A surge protective element characterized in that the porous metal layer is formed of tungsten.

Insulating tube and
A pair of sealing electrodes for closing the openings at both ends of the insulating tube and sealing the discharge control gas inside are provided.
The pair of sealing electrodes has a pair of protruding electrode portions that project inward and face each other.
A porous metal layer is provided on the facing surfaces of the pair of protruding electrode portions, and a discharge active layer formed of a material having higher electron emission characteristics than the material of the sealing electrode is formed in the porous metal layer. It is provided on the surface of the porous metal layer in a state where at least a part of the metal layer is inserted into the porous metal layer.
A surge protective element characterized in that the porous metal layer is also provided on the outer peripheral surface of the protruding electrode portion.

In the surge protection element according to any one of claims 1 to 3.
A surge protective element characterized in that the porous metal layer is a porous metal plate attached to the protruding electrode portion.

Insulating tube and
A pair of sealing electrodes for closing the openings at both ends of the insulating tube and sealing the discharge control gas inside are provided.
The pair of sealing electrodes has a pair of protruding electrode portions that project inward and face each other.
A porous metal layer is provided on the facing surfaces of the pair of protruding electrode portions, and a discharge active layer formed of a material having higher electron emission characteristics than the material of the sealing electrode is formed in the porous metal layer. It is provided on the surface of the porous metal layer in a state where at least a part of the metal layer is inserted into the porous metal layer.
The porous metal layer is a porous metal plate attached to the protruding electrode portion.
A surge protective element characterized in that the porous metal plate is formed of a foamed metal body.

Insulating tube and
A pair of sealing electrodes for closing the openings at both ends of the insulating tube and sealing the discharge control gas inside are provided.
The pair of sealing electrodes has a pair of protruding electrode portions that project inward and face each other.
A porous metal layer is provided on the facing surfaces of the pair of protruding electrode portions, and a discharge active layer formed of a material having higher electron emission characteristics than the material of the sealing electrode is formed in the porous metal layer. It is provided on the surface of the porous metal layer in a state where at least a part of the metal layer is inserted into the porous metal layer.
The porous metal layer is a porous metal plate attached to the protruding electrode portion.
A surge protection element characterized in that the porous metal plate is formed of a metal fiber sintered body obtained by sintering metal fibers.

Insulating tube and
A pair of sealing electrodes for closing the openings at both ends of the insulating tube and sealing the discharge control gas inside are provided.
The pair of sealing electrodes has a pair of protruding electrode portions that project inward and face each other.
A porous metal layer is provided on the facing surfaces of the pair of protruding electrode portions, and a discharge active layer formed of a material having higher electron emission characteristics than the material of the sealing electrode is formed in the porous metal layer. It is provided on the surface of the porous metal layer in a state where at least a part of the metal layer is inserted into the porous metal layer.
The porous metal layer is a porous metal plate attached to the protruding electrode portion.
A surge protection element characterized in that the porous metal plate is a sintered body obtained by sintering metal powder and is formed of a metal powder sintered body having a plurality of voids inside.

It is provided with an insulating tube and a pair of sealing electrodes that close the openings at both ends of the insulating tube to seal the discharge control gas inside, and the pair of sealing electrodes project inward and face each other. It has a pair of protruding electrode portions, a porous metal layer is provided on the facing surface of the pair of protruding electrode portions, and the discharge activity is formed of a material having higher electron emission characteristics than the material of the sealing electrode. A method of manufacturing a surge protection element provided on the surface of the porous metal layer in a state where at least a part of the layer is embedded in the porous metal layer .
A step of forming the porous metal layer on the facing surface of the protruding electrode portion, and a step of forming the porous metal layer.
It has a discharge active layer forming step of forming the discharge active layer on the surface of the porous metal layer.
In the discharge active layer forming step, a step of adhering an ion source material containing a material having higher electron emission characteristics than the material of the sealing electrode to the porous metal layer, and
A method for manufacturing a surge protective element, which comprises a step of heat-treating the ion source material to form the discharge active layer.

It is provided with an insulating tube and a pair of sealing electrodes that close the openings at both ends of the insulating tube to seal the discharge control gas inside, and the pair of sealing electrodes project inward and face each other. It has a pair of protruding electrode portions, a porous metal layer is provided on the facing surface of the pair of protruding electrode portions, and the discharge activity is formed of a material having higher electron emission characteristics than the material of the sealing electrode. A method of manufacturing a surge protection element provided on the surface of the porous metal layer in a state where at least a part of the layer is embedded in the porous metal layer .
A step of forming the porous metal layer on the facing surface of the protruding electrode portion, and a step of forming the porous metal layer.
It has a discharge active layer forming step of forming the discharge active layer on the surface of the porous metal layer.
In the discharge active layer forming step, a step of adhering an ion source material containing a material having higher electron emission characteristics than the material of the sealing electrode to the porous metal layer, and
It has a step of heat-treating the ion source material to form the discharge active layer.
A method for manufacturing a surge protective element, which comprises spraying a molten metal onto a surface facing the protruding electrode portion to form the porous metal layer in the porous metal layer forming step.