JP2018092754A - Surge protective element and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a surge protective element which can suppress expansion of an ion source material, and can achieve high adhesion and crystallinity; and a manufacturing method of the surge protective element.SOLUTION: A surge protective element comprises: an insulation tube 2; and a pair of sealing electrodes 3 which close openings on both ends of the insulation tube so as to internally seal discharge control gas. The pair of sealing electrodes have a pair of protruding electrode parts 5 which protrude inward so as to face each other. Facing faces 5a of the pair of protruding electrode parts are each provided with a porous metal layer 8. At the same time, a discharge active layer 9, which is made of a material having a superior electron emission characteristic to that of the sealing electrodes, is formed on the surface of the porous metal layer in such a manner that at least part thereof is embedded in the porous metal layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a surge protection element used for protecting various devices from surges caused by lightning strikes and preventing accidents, and a method for manufacturing the same.

  Abnormal voltage such as lightning surge and static electricity, etc., such as parts where electronic devices for communication equipment such as telephones, facsimiles and modems are connected to communication lines, power lines, antennas or image display drive circuits such as CRTs, liquid crystal televisions and plasma televisions A surge protection element is connected to a portion that is easily subjected to electric shock due to (surge voltage) in order to prevent damage due to thermal damage or ignition of an electronic device or a printed circuit board on which the device is mounted due to abnormal voltage.

  Conventionally, as shown in Patent Document 1, for example, an arrester-type surge protection element having a pair of protruding electrode portions protruding in a facing state from a pair of sealing electrodes and having a discharge auxiliary portion formed on the inner surface of an insulating tube is provided. Have been described. In this surge protection element, a large number of substantially rectangular parallelepiped holes are arranged and formed on the opposing surfaces of a pair of protruding electrode parts in a substantially matrix shape, and vanadium pentoxide-zinc oxide-oxide as an ion source material is formed on the inner surface of each hole part. A film containing barium-tellurium dioxide glass is formed.

  This ion source material is provided on the opposing surface of the protruding electrode portion for the purpose of controlling the discharge voltage and protecting the electrode. Further, the numerous holes are formed as irregularities for obtaining retention of the ion source material and uniform application. That is, the ion source material is attached to the unevenness formed on the opposing surface of the protruding electrode portion, and the drop is prevented using the anchor effect.

Utility Model Registration No. 3151069

The following problems remain in the conventional technology.
That is, the ion source material is adhered to the unevenness of the opposing surface of the protruding electrode portion, but it is required to form the ion source material with a higher adhesion force in order to improve arc resistance. 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 lump of the ion source material during heat treatment, the more gas such as vapor is generated by dehydration reaction due to thermal decomposition during heat treatment. Occurs and swelling of the ion source material occurs. Due to the swelling, there is a problem that the density of the ion source material is lowered and the crystallinity is lowered. When the degree of crystallinity is low in this way, it has been a cause of lowering the resistance to ion source material dropping and scattering due to repeated surges and arc discharge. In addition, the higher the temperature during heat treatment, the higher the crystallinity, but once it swells, there is a disadvantage that the density decreases and hinders the crystallization of the ion source material.

  The present invention has been made in view of the above-described problems, and provides a surge protection element that can suppress swelling of an ion source material and can obtain high adhesion and crystallinity, and a method for manufacturing the same. With the goal.

  The present invention employs the following configuration in order to solve the above problems. That is, the surge protection element according to the first aspect of the present invention includes an insulating tube and a pair of sealing electrodes that closes both end openings of the insulating tube and seals the discharge control gas inside. The sealing electrode has a pair of protruding electrode portions protruding inward and facing each other, and a porous metal layer is provided on the opposing surfaces of the pair of protruding electrode portions, and the sealing electrode material Further, the 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 part of the discharge active layer enters the porous metal layer.

  In this surge protection element, a porous metal layer is provided on the opposing 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 porous. Since it is provided on the surface of the porous metal layer with at least part of it entering the metal layer, the discharge active layer enters the voids (pores) in the porous metal layer, and higher adhesion can be obtained than before. . Further, when the ion source material attached to the porous metal layer is heat-treated to form the discharge active layer, the ion source material is uniformly finely dispersed in the voids in the porous metal layer and is generated. Since vapor or the like escapes to the outside through the gap, the occurrence of blistering is suppressed and the crystallinity of the discharge active layer is improved.

A surge protection element according to a second invention is characterized in that, in the first invention, the porous metal layer is made of tungsten.
That is, in this surge protection element, since the porous metal layer is formed of tungsten, arc resistance is further improved by tungsten, which is a refractory metal.

A surge protection element according to a third invention is characterized in that, in the first or second invention, the porous metal layer is also provided on an outer peripheral surface of the protruding electrode portion.
That is, in this surge protection 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 arc resistance is further improved.

A surge protection element according to a 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 part, the porous metal plate is prepared separately and attached only by heat welding or brazing material. 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.

A surge protection element according to a fifth aspect of the present invention is characterized in that, in the fourth aspect, the porous metal plate is formed of a foam metal body.
That is, in this surge protection element, since the porous metal plate is formed of a foam metal body, a porous metal layer having a high porosity can be obtained by the foam metal body including a large number of pores.

According to a sixth aspect of the present invention, the surge protection element according to the fourth aspect is characterized in that 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 is obtained. It is done.

A surge protection element according to a seventh invention is the surge protection element according to the fourth invention, wherein the porous metal plate is a sintered body obtained by sintering metal powder and having a plurality of voids therein. It is formed.
That is, in this surge protection element, the porous metal plate is a sintered body obtained by sintering metal powder, and is formed by a metal powder sintered body having a plurality of voids inside. A porous metal layer having a large number of voids is obtained.

A method for manufacturing a surge protection element according to an eighth invention is a method for manufacturing the surge protection element according to any one of the first to seventh inventions, wherein the porous metal layer is formed on the opposing surface of the protruding electrode portion. A porous metal layer forming step for forming, and a discharge active layer forming step for forming the discharge active layer on the surface of the porous metal layer, wherein the ion source material is the porous material in the discharge active layer forming step. It has the process of attaching to a metal layer, and the process of heat-processing the said ion source material, and forming the said discharge active layer, It is characterized by the above-mentioned.
That is, in this surge protection element manufacturing method, in the discharge active layer forming step, the ion source material is attached to the porous metal layer, and the ion source includes a material having higher electron emission characteristics than the material of the sealing electrode. And a step of forming a discharge active layer by heat-treating the material, so that the ion source material is uniformly finely dispersed in the voids in the porous metal layer, and the vapor generated during the heat treatment passes through the voids. Therefore, the occurrence of blistering is suppressed, and the crystallinity of the discharge active layer is improved.

A method for manufacturing a surge protection element according to a ninth aspect of the invention is a method for manufacturing the surge protection element according to any one of the first to third aspects, wherein the porous metal layer is provided on the opposing surface of the protruding electrode portion. 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. In the discharge active layer forming step, from the material of the sealing electrode A step of adhering an ion source material containing a material having a high electron emission property to the porous metal layer; and a step of heat-treating the ion source material to form the discharge active layer. In the forming step, the porous metal layer is formed by spraying a molten metal on the opposing surface of the protruding electrode portion.
That is, in this method of manufacturing a surge protection element, in the porous metal layer forming step, the metal melt is sprayed on the opposing surface of the protruding electrode portion to form the porous metal layer. Since a large number of voids (pores) are generated in the deposited metal, a porous metal layer can be easily obtained.

The present invention has the following effects.
That is, according to the surge protection element and the manufacturing method thereof according to the present invention, the porous metal layer is provided on the opposing surfaces of the pair of protruding electrode portions, and is formed of a material having higher electron emission characteristics than the material of the sealing electrode. Since the discharge active layer is provided on the surface of the porous metal layer in a state where at least part of the discharge active layer has entered the porous metal layer, high adhesion and crystallinity of the discharge active layer can be obtained, The occurrence of swelling during heat treatment is suppressed.
Therefore, in the surge protection device according to the present invention, resistance to arc discharge is improved, surge withstand characteristics are improved, and stable discharge is possible. As a result, the fluctuation range of the discharge start voltage can be reduced, electrode damage can be reduced, and the lifetime of the element (increased number of operable surges) can be contributed.
In particular, the surge protection element according to the present invention is suitable for power supplies and communication facilities for infrastructure (railway-related, renewable energy-related (solar cell, wind power generation, etc.)) that require high current surge resistance. In addition, since the surge resistance is improved, the element can be miniaturized and can be applied to a small electronic device and a mounting substrate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an axial sectional view showing a first embodiment of a surge protection element and a method for manufacturing the same according to the present invention. In 1st Embodiment, it is an expanded sectional view which shows the principal part. It is AA arrow sectional drawing of FIG. It is sectional drawing of the axial direction which shows 2nd Embodiment of the surge protection element which concerns on this invention, and its manufacturing method. It is sectional drawing of the axial direction which shows 3rd Embodiment of the surge protection element which concerns on this invention, and its manufacturing method. It is sectional drawing of the axial direction which shows 4th Embodiment of the surge protection element which concerns on this invention, and its manufacturing method.

  Hereinafter, a first embodiment of a surge protection element and a method for manufacturing the same according to the present invention will be described with reference to FIGS. In each drawing used for the following description, the scale is appropriately changed in order to make each member recognizable or easily recognizable.

As shown in FIG. 1, the surge protection element 1 of the present embodiment includes an insulating tube 2 and a pair of sealing electrodes 3 that closes both ends of the insulating tube 2 and seals the discharge control gas inside. And.
The pair of sealing electrodes 3 has a pair of protruding electrode portions 5 that protrude inward and face each other.
As shown in FIG. 2, a porous metal layer 8 is provided on the opposing surfaces 5 a of the pair of protruding electrode portions 5, and is 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 part of the discharge active layer 9 enters the porous metal layer 8. That is, the discharge active layer 9 is formed in a state of penetrating into the voids in the porous metal layer 8.

The porous metal layer 8 is formed of tungsten, for example, and is formed by spraying a molten metal of tungsten on the protruding electrode portion 5.
The porous metal layer 8 is also provided on the outer peripheral surface of the protruding electrode portion 5.
In addition, the surge protection element 1 of this embodiment is provided with the discharge auxiliary | assistant part 4 formed with the ion source material in the inner peripheral surface of the insulating tube 2. FIG.

The discharge active layer 9 includes, for example, Si and O as main component elements and at least one of Na, Cs, and C as an ion source material. The discharge active layer 9 is prepared, for example, by adding a cesium carbonate powder to a sodium silicate solution to apply a precursor to the porous metal layer 8 and then attaching the precursor to the porous metal layer 8. The heat treatment is performed at a temperature higher than the temperature at which sodium is softened and higher than the temperature at which cesium carbonate is melted and decomposed.
In the present embodiment, the discharge active layer 9 is formed at the center of the porous metal layer 8 on the facing surface 5a.

The discharge auxiliary part 4 is a conductive material and is a discharge auxiliary part made of, for example, a carbon material.
In the present embodiment, the discharge auxiliary 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 along the axis C is shown, but a plurality of discharge assisting portions 4 may be formed at intervals in the circumferential direction.

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 disk-like flange portion 7 that is fixed in close contact by a heat treatment with a conductive adhesive (not shown) at both ends of the insulating tube 2. A cylindrical 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 inside the flange portion 7.

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 fusing material is formed of, for example, an Ag—Cu brazing material as a brazing material containing Ag.
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 , the atmosphere, etc. and a mixed gas thereof are employed.

The porous metal layer 8 is a porous metal layer having a large number of voids (pores). For example, the gap interval is 100 nm to 300 μm. Further, the porosity of the porous metal layer 8 is set to 50 to 98%.
In addition, when the porosity exceeds 98%, the structure strength is lowered, and the surface is easily damaged by a surge (arc discharge).

The method for manufacturing the surge protection element 1 includes a porous metal layer forming step for forming the porous metal layer 8 on the opposing surface 5 a of the protruding electrode portion 5, and a discharge active layer 9 formed on the surface of the porous metal layer 8. A discharge active layer forming step.
In the discharge active layer forming step, an ion source material including a material having electron emission characteristics higher than that of the material of the sealing electrode 3 is attached to the porous metal layer 8, and the ion source material is heat treated to discharge the active layer 9. Forming the step.
Further, in the porous metal layer forming step, the molten metal is sprayed on the facing surface 5 a of the protruding electrode portion 5 to form the porous metal layer 8. In addition, plasma spraying is employ | adopted for thermal spraying, and the molten metal of tungsten is used as a molten metal.

  In the surge protection element 1 manufactured in this way, when an overvoltage or overcurrent enters, first, an initial discharge is performed between the discharge auxiliary 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 arc discharge is performed from the various portions 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.

  As described above, in the surge protection device 1 of the present embodiment, the porous metal layer 8 is provided on the opposing surfaces 5 a of the pair of protruding electrode portions 5, and the material has higher electron emission characteristics than the material of the sealing electrode 3. Is formed on the surface of the porous metal layer 8 in a state where at least a part of the discharge active layer 9 is formed in the porous metal layer 8. The adhering force is higher than the conventional one.

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.
Moreover, 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 arc resistance is further improved.

Further, in the method of manufacturing the surge protection element 1, in the discharge active layer forming step, a step of attaching 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 and finely dispersed in the voids in the porous metal layer 8, and the vapor generated during the heat treatment escapes to the outside through the voids, so that the occurrence of swelling is suppressed. The crystallinity of the discharge active layer 9 is improved.
Further, in the porous metal layer forming step, the metal melt is sprayed on the facing surface 5a of the protruding electrode portion 5 to form the porous metal layer 8, so that the metal inner surface adhering to the facing surface 5a of the protruding electrode portion 5 by spraying can be reduced. Since a large number of voids (pores) are formed in the porous metal layer 8, the porous metal layer 8 can be easily obtained.

  Next, second and third embodiments of the surge protection element according to the present invention will be described below with reference to FIGS. In the following description of each embodiment, the same constituent elements described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

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. The porous metal plate is formed of a foam metal body.
That is, in the second embodiment, a porous metal layer 28 is formed by bonding a porous metal plate formed of a foam metal body such as tungsten to the protruding electrode portion 5 by heat welding or brazing material.
In the second embodiment, the porous metal layer 28 is not formed on the outer peripheral surface of the protruding electrode portion 5.

Thus, 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, a porous metal plate is separately manufactured and subjected to thermal welding or the like. The porous metal layer 28 can be easily formed simply 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 formed of a foam metal body, the porous metal layer 28 having a high porosity can be obtained from the foam metal body including a large number of pores.

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 foam metal body, whereas the surge protection element of the third embodiment. In 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 porous metal layer 38 is formed by bonding a metal fiber sintered body obtained by sintering metal fibers such as tungsten to the protruding electrode portion 5 by heat welding or brazing.
As described above, in the surge protection element 31 according to the third embodiment, the porous metal plate is formed of a metal fiber sintered body obtained by sintering metal fibers, and thus has a dense structure having a large number of voids between the metal fibers. A porous metal layer 38 is obtained.

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 foam metal body, whereas the surge protection element of the fourth embodiment. In 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 therein.
That is, in the fourth embodiment, a metal powder sintered body obtained by sintering metal powder such as tungsten so as to have a porosity of 30 to 90%, for example, is bonded to the protruding electrode portion 5 by heat welding or brazing material. A porous metal layer 48 is formed.
Thus, in the surge protection element 41 of the fourth embodiment, 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 therein. Therefore, the porous metal layer 48 having a large number of voids between the metal powders is obtained.

The technical scope of the present invention is not limited to the above embodiments and examples, 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 liquid ion source material described above is applied to and attached to the opposing surface of the protruding electrode portion. As an attachment method, the opposing surface of the protruding electrode portion is applied to the ion source. The ion source material may be attached to the facing surface by being immersed in a precursor of the material.

  Reference numerals 1, 21, 31, 41 ... surge protection element, 2 ... insulating tube, 3 ... sealing electrode, 4 ... discharge auxiliary part, 5 ... protruding electrode part, 5a ... opposite surface of protruding electrode part, 9 ... discharge active layer , 28, 38, 48 ... porous metal layer

Claims (9)

An insulating tube;
A pair of sealing electrodes for closing the opening at both ends of the insulating tube and sealing the discharge control gas inside;
The pair of sealing electrodes has a pair of protruding electrode portions protruding inward and facing each other,
A porous metal layer is provided on the opposing 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. A surge protection element characterized in that the surge protection element is provided on the surface of the porous metal layer in a state where at least a part of the metal layer enters. The surge protection element according to claim 1,
A surge protection element, wherein the porous metal layer is made of tungsten. The surge protection element according to claim 1 or 2,
The surge protection element according to claim 1, wherein the porous metal layer is also provided on an outer peripheral surface of the protruding electrode portion. In the surge protection element according to any one of claims 1 to 3,
The surge protection element according to claim 1, wherein the porous metal layer is a porous metal plate attached to the protruding electrode portion. The surge protection element according to claim 4,
A surge protection element, wherein the porous metal plate is formed of a foam metal body. The surge protection element according to claim 4,
A surge protection element, wherein the porous metal plate is formed of a metal fiber sintered body obtained by sintering metal fibers. The surge protection element according to claim 4,
A surge protection element, wherein the porous metal plate is a sintered body obtained by sintering a metal powder and has a plurality of voids therein. A method for manufacturing the surge protection element according to any one of claims 1 to 7,
A porous metal layer forming step of forming the porous metal layer on the opposing surface of the protruding electrode portion;
A discharge active layer forming step of forming the discharge active layer on the surface of the porous metal layer,
A step of attaching an ion source material containing a material having electron emission characteristics higher than that of the material of the sealing electrode to the porous metal layer in the discharge active layer forming step;
And a step of forming the discharge active layer by heat-treating the ion source material. A method for manufacturing the surge protection element according to any one of claims 1 to 3,
A porous metal layer forming step of forming the porous metal layer on the opposing surface of the protruding electrode portion;
A discharge active layer forming step of forming the discharge active layer on the surface of the porous metal layer,
A step of attaching an ion source material containing a material having electron emission characteristics higher than that of the material of the sealing electrode to the porous metal layer in the discharge active layer forming step;
And heat-treating the ion source material to form the discharge active layer,
In the said porous metal layer formation process, the molten metal is sprayed on the opposing surface of the said protruding electrode part, and the said porous metal layer is formed, The manufacturing method of the surge protection element characterized by the above-mentioned.

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