JP2012114351A - Anti-static element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anti-static element and the like in which not only the discharge characteristics are excellent but also durability for repeated use is enhanced.SOLUTION: In the anti-static element 100 comprising an insulating laminate 11, electrodes 21, 22 arranged to face each other in the insulating laminate 11 with a space between one other, a gap located between the electrodes 21, 22, and a discharge inducing part 31 arranged at least in the gap, electrodes 21, 22 containing a conductive metal oxide are used. Preferably, the conductive metal oxide has a resistivity of 10-10Ωm. The conductive metal oxide is preferably a sintered compact.

Description

  The present invention relates to an anti-static element, and more particularly to an anti-static element useful for use in a high-speed transmission system or in combination with a common mode filter.

  In recent years, electronic devices have been rapidly reduced in size and performance. In addition, the transmission speed is increased (higher frequency exceeding 1 GHz) as typified by high-speed transmission systems such as antenna circuits for mobile phones, RF modules, USB 2.0 and USB 3.0, S-ATA2, and HDMI. And the progress of lower drive voltage is remarkable. On the other hand, the withstand voltage of the electronic components used in the electronic device is reduced as the electronic device is downsized and the drive voltage is reduced. Therefore, protection of electronic components from overvoltage typified by electrostatic pulses generated when the human body and terminals of the electronic device come into contact has become an important technical issue.

  Conventionally, in order to protect an electronic component from such an electrostatic pulse, a method of providing a laminated varistor between a line where static electricity enters and a ground is generally employed. However, since the multilayer varistor generally has a large capacitance, it becomes a factor that degrades signal quality when used in a high-speed transmission system. Further, in the antenna circuit and the RF module, it is impossible to use an electrostatic protection component having a large electrostatic capacity. Therefore, development of an electrostatic countermeasure element having a small electrostatic capacity that can be applied to a high-speed transmission system is required.

  As an anti-static element having a low capacitance, an element in which an electrostatic protection material is filled between electrodes that are spaced apart from each other has been proposed. An antistatic element equipped with this type of so-called gap-type electrode has features such as a large insulation resistance, a small capacitance, and a good responsiveness. Such as melting, deformation, dropping off, etc.).

  As a technique for suppressing the destruction of this type of electrode, for example, Patent Document 1 discloses a pair of first electrodes and a part of the first electrodes that overlaps and is electrically connected to the first electrodes. A pair of second electrodes, the pair of first electrodes is formed using a material having a specific resistance lower than that of the pair of second electrodes, and the pair of second electrodes. An anti-static component is described in which the electrode is formed thinner than the pair of first electrodes. In this technique, the first electrode is formed using a material having a small specific resistance such as gold, thereby suppressing heat generation in the first electrode, and a material having a high melting point (metal such as nickel, tungsten, or molybdenum). In addition, the second electrode is formed using aluminum on which an aluminum oxide film is formed, and a gap is formed between the second electrodes, thereby increasing resistance to repeated application of static electricity.

International Publication No. 2008/155916

  However, in the technique described in Patent Document 1, the effect of suppressing the destruction (melting, deformation, dropout, etc.) of the electrode due to heat or stress generated by the discharge is insufficient, and therefore, the gap or There is a problem that a short circuit between the electrodes is likely to occur due to a part of the electrode dropping out or a melt of the electrode is generated around the gap, and durability during repeated use is insufficient. .

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an anti-static element that not only has excellent discharge characteristics but also has improved durability for repeated use. Another object of the present invention is to provide an anti-static element that not only has excellent discharge characteristics and durability for repeated use, but also has a small capacitance.

  In order to solve the above-described problems, the present inventors have conducted extensive research and as a result, in an anti-static element equipped with a so-called gap-type electrode, include an electrically conductive metal oxide as an electrode that causes discharge between gaps. The inventors have found that the above problems can be solved by employing an electrode, and have completed the present invention.

  That is, an antistatic element according to the present invention includes an insulating laminate, electrodes spaced apart from each other in the insulating laminate, a gap positioned between the electrodes, and at least the gap. A discharge inducing part, wherein the electrode includes a conductive metal oxide.

  The inventors measured the characteristics of the anti-static element configured as described above, and found that not only the discharge characteristics were excellent, but also the durability of repeated use was enhanced. The details of the mechanism of action that produces this effect are not yet clear, but are estimated as follows, for example.

  That is, in the anti-static element having the above-described configuration, an electrode including a conductive metal oxide is employed as an electrode that generates a discharge between the gaps. An electrode including such a conductive metal oxide is excellent in balance of conductivity, heat resistance and mechanical strength as compared with an electrode made of metal such as nickel, tungsten or molybdenum used in the prior art. Therefore, by adopting an electrode containing this conductive metal oxide, it is possible to alleviate the destruction (melting, deformation, dropout, etc.) of the electrode due to heat or stress generated by the discharge without excessively impairing the conductivity. As a result, a short circuit between the electrodes during repeated use is suppressed. As a result of a combination of these actions, it is surmised that the antistatic element having the above-described configuration not only has excellent discharge characteristics, but also has improved durability during repeated use. In order to alleviate the destruction of the electrode, it was considered to employ an electrode provided with an insulating metal oxide such as aluminum oxide on the surface of a metal electrode having excellent conductivity. This is not suitable because the conductivity (discharge property) of the electrode is excessively impaired, such as an increase in starting voltage. However, the action is not limited to these.

Here, the conductive metal oxide preferably has a resistivity of 10 ⁻⁷ Ωm or more and 10 ⁵ Ωm or less. By using a conductive metal oxide having such a resistivity (conductivity), it is possible to realize an anti-static element having excellent discharge characteristics and durability during repeated use with good reproducibility.

  The conductive metal oxide is preferably a sintered body. Since the sintered body of the conductive metal oxide is particularly excellent in heat resistance and mechanical strength, the durability of the antistatic element can be remarkably enhanced by using the sintered body.

  Furthermore, it is preferable that the conductive metal oxide is a particle, and the electrode has an accumulation structure of the conductive metal oxide particle. In an electrode in which such a particle-shaped conductive metal oxide is integrated, heat and stress generated by discharge are absorbed by gaps existing between the particles, and as a result, the destruction of the electrode can be mitigated. In addition, the durability of the anti-static element can be remarkably enhanced during repeated use.

  In the electrostatic countermeasure element having the above configuration, the gap distance ΔG between the electrodes is preferably 70 μm or less. If comprised in this way, a discharge start voltage will be reduced etc., and a discharge characteristic will be improved.

In addition, it is preferable that the electrostatic countermeasure element having the above configuration further includes a lead electrode having a resistivity of less than 10 ⁻⁷ Ωm, and the electrode is electrically connected to an external circuit through the lead electrode. When the lead electrode is employed in this manner, the resistance value of the entire element can be reduced and the amount of heat generated during discharge can be reduced, and as a result, the discharge characteristics and durability during repeated use can be further enhanced.

  Furthermore, in the electrostatic protection element having the above-described configuration, the discharge inducing portion is preferably a composite in which a conductive inorganic material is discontinuously dispersed in a matrix of an insulating inorganic material. Since this type of composite has a small electrostatic capacity and functions as an electrostatic protection material that can be discharged even at a relatively low voltage, a high-performance antistatic element having excellent discharge characteristics can be realized. In addition, since an inorganic composite is used as the electrostatic protection material, the heat resistance is remarkably improved and the weather resistance to the external environment such as temperature and humidity is remarkably improved.

  In this specification, “composite” means a state in which a conductive inorganic material is dispersed in a matrix of insulating inorganic material, and the conductive inorganic material is uniformly or in the matrix of insulating inorganic material. The concept includes not only a randomly dispersed state but also a state in which aggregates of conductive inorganic materials are dispersed in a matrix of an insulating inorganic material, that is, a state generally called a sea-island structure. In this specification, “insulation” in the discharge inducing portion means 0.1 Ωcm or more, and “conductivity” in the discharge inducing portion means less than 0.1 Ωcm, so-called “semiconductive” in the discharge inducing portion. As long as the specific resistance is 0.1 Ωcm or more, the property is included in the former insulation.

In the above, the insulating inorganic material includes Al ₂ O ₃ , SrO, CaO, BaO, TiO ₂ , SiO ₂ , ZnO, In ₂ O ₃ , NiO, CoO, SnO ₂ , V ₂ O ₅ , CuO, MgO, It is preferably at least one selected from the group consisting of ZrO ₂ , Bi ₂ O ₃ , AlN, BN and SiC. Since these metal compounds are excellent in insulation, heat resistance and weather resistance, they function effectively as a material constituting the insulating matrix of the composite, and as a result, high performance static electricity with excellent discharge characteristics, heat resistance and weather resistance. A countermeasure element can be realized.

  The conductive inorganic material is at least one metal selected from the group consisting of C, Ni, Al, Fe, Cu, Ti, Cr, Au, Ag, Pd, and Pt, or a metal compound thereof. Is preferred. By forming a state in which these metals or metal compounds are discontinuously dispersed in a matrix of an insulating inorganic material, a high-performance antistatic element excellent in discharge characteristics, heat resistance and weather resistance can be realized.

  According to the present invention, it is possible to realize an anti-static element that not only has excellent discharge characteristics but also has improved durability for repeated use. Moreover, according to the preferable aspect of this invention, not only is it excellent in discharge characteristics and durability of repeated use, but also an electrostatic countermeasure element having a small capacitance can be realized. Furthermore, according to the other preferable aspect of this invention, heat resistance and a weather resistance can also be improved exceptionally.

1 is a schematic cross-sectional view schematically showing an antistatic element 100 according to a first embodiment. It is a schematic cross section which shows roughly the antistatic element 200 of 2nd Embodiment. It is a schematic cross section which shows roughly the antistatic element 300 of 3rd Embodiment. It is a schematic cross section which shows schematically the static electricity countermeasure element 400 of 4th Embodiment. 6 is a schematic cross-sectional view schematically showing a modification of the anti-static element 200. FIG. 6 is a schematic cross-sectional view schematically showing a modification of the anti-static element 200. FIG. 5 is a schematic perspective view showing a manufacturing process of the anti-static element 200. FIG. 5 is a schematic perspective view showing a manufacturing process of the anti-static element 200. FIG. 5 is a schematic perspective view showing a manufacturing process of the anti-static element 200. FIG. 5 is a schematic perspective view showing a manufacturing process of the anti-static element 400. FIG. 5 is a schematic perspective view showing a manufacturing process of the anti-static element 400. FIG. 5 is a schematic perspective view showing a manufacturing process of the anti-static element 400. FIG. It is a circuit diagram in an electrostatic discharge test.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios. Further, the following embodiments are exemplifications for explaining the present invention, and are not intended to limit the present invention only to the embodiments.

(First embodiment)
FIG. 1 is a schematic cross-sectional view schematically showing the antistatic element of the present embodiment.
The electrostatic protection element 100 includes an insulating laminate 11, a pair of rectangular electrodes 21 and 22 disposed opposite to each other in the insulating laminate 11, and a position between the electrodes 21 and 22. A discharge inducing portion 31 disposed in the gap and a terminal electrode 41 (not shown) electrically connected to the electrodes 21 and 22. The electrostatic protection element 100 is made by a lamination method, and a pair of electrodes 21 and 22 are embedded in the insulating laminate 11. In the electrostatic protection element 100, the electrodes 21 and 22 are electrically connected to an external circuit via the terminal electrode 41, and the discharge inducing portion 31 functions as an electrostatic protection material that can be discharged even at a relatively low voltage. Thus, it is designed such that initial discharge is secured between the electrodes 21 and 22 via the discharge inducing portion 31 when an overvoltage such as static electricity is applied from the outside.

  The insulating laminate 11 is obtained by laminating a plurality of insulating substrates 12 (12a, 12b, 12c, 12d, 12e, 12f, 12g, 12h) having an insulating surface 13. As long as the insulating laminated body 11 can support at least the electrodes 21, 22 and the discharge inducing portion 31, the dimension shape and the number of laminated insulating substrates 12 are not particularly limited. Here, the insulating substrate 12 having the insulating surface 13 is a concept including a substrate made of an insulating material and an insulating film formed on a part or the entire surface of the substrate.

  Specific examples of the insulating substrate 12 include a ceramic substrate using a low dielectric constant material having a dielectric constant of 50 or less, preferably 20 or less, such as alumina, silica, magnesia, aluminum nitride, and forsterite.

  On the insulating surface 13 of the insulating laminate 11 facing the insulating substrates 12d and 12e, electrodes 21 and 22 containing a conductive metal oxide are disposed, respectively. In the present embodiment, the pair of electrodes 21 and 22 are disposed so as to partially overlap in the approximate center in the plan view of the insulating substrates 12d and 12h, and the pair of electrodes 21 and 22 is an insulating laminate. 11 are opposed to each other with a gap distance ΔG. The gap distance ΔG means the shortest distance between the pair of electrodes 21 and 22.

Specific examples of the conductive metal oxide included in the electrodes 21 and 22 include, for example, CaMnO ₃ and LaNiO ₃ in which part of the Ca site is replaced with La, ZnO, ITO, and Ca ₃ Co ₄ O in which part of the Ca site is replaced with Al. ₉ , RuO ₂ , SrTiO ₃ in which a part of the Sr site is substituted with Nb, NiO in which a part of the Sr site is substituted with Li, NiO.Fe ₂ O _{3, and the} like are exemplified, but not limited thereto. A conductive metal oxide may be used individually by 1 type, or may use 2 or more types together.

Here, the conductive metal oxide contained in the electrodes 21 and 22 has a resistivity of 10 ⁻⁷ Ωm or more 10 or more from the viewpoint of realizing the antistatic element 100 having excellent discharge characteristics and durability during repeated use with good reproducibility. It is preferably ⁵ Ωm or less.

  The conductive metal oxide contained in the electrodes 21 and 22 is preferably a sintered body. Further, since the heat resistance and the mechanical strength are particularly excellent, the durability when the antistatic device 100 is repeatedly used is remarkably enhanced by using this.

The electrodes 21 and 22 may contain other components in addition to the conductive metal oxide described above. Specific examples of other components that may be included in the electrodes 21 and 22 include, for example, Al ₂ O ₃ , SrO, CaO, BaO, TiO ₂ , SiO ₂ , ZnO, In ₂ O ₃ , NiO, CoO, and SnO. ₂ , V ₂ O ₅ , CuO, MgO, ZrO ₂ , Bi ₂ O ₃ , AlN, BN, SiC, forsterite, glass, etc., an insulating inorganic material or semiconducting inorganic material with a resistivity exceeding 10 ⁵ Ωm; resistance rate is 10 ^-7 [Omega] m below metal or alloy: the metal oxide of the resistance ratio is less than 10 ^-7 [Omega] m, a metal nitride, metal carbides, metal borides, carbon, binder, dispersing agent, but the solvent and the like, It is not specifically limited to these.

  The conductive metal oxide contained in the electrodes 21 and 22 preferably has a particle shape. The electrodes 21 and 22 obtained by accumulating conductive metal oxides having a particle shape can absorb (relax) heat and stress generated during discharge due to gaps existing between the particles. Therefore, by using this, the electrode destruction at the time of discharge is suppressed, and the durability at the time of repeated use of the antistatic element 100 is remarkably enhanced. Here, the particle shape of the conductive metal oxide is not particularly limited, and may be any one of, for example, a spindle shape, a columnar shape, a spherical shape with an aspect ratio of 1 to 5, an elliptical spherical shape with an aspect ratio exceeding 5, and an indefinite shape. It doesn't matter. The average particle size of the conductive metal oxide particles can be set as appropriate and is not particularly limited, but is preferably about 0.1 to 2 μm. In the present specification, the average particle diameter means the median diameter (D50) when spherical, and the arithmetic mean value of the major axis and minor axis.

  The thickness of the electrodes 21 and 22 can be appropriately set and is not particularly limited, but is usually about 0.1 to 20 μm. Moreover, in this embodiment, although the electrodes 21 and 22 are formed in the rectangular shape by planar view, the shape in particular is not restrict | limited, For example, you may be formed in the comb-tooth shape or the saw shape. .

  The gap distance ΔG between the electrodes 21 and 22 may be appropriately set in consideration of desired discharge characteristics, and is not particularly limited, but is usually about 0.1 to 70 μm. From the viewpoint of securing a low-voltage initial discharge, the gap distance ΔG between the electrodes 21 and 22 is preferably 50 μm or less.

  The formation method of the electrodes 21 and 22 is not specifically limited, A well-known method can be selected suitably. Specifically, for example, conductive metal oxide (conductive metal oxide particles or sintered particles) and, if necessary, a mixture (mixture, dispersion, mixed paste) containing other components such as a solvent and a binder ), The mixture is applied onto the insulating surface 13 of the insulating substrates 12d and 12e, and the electrodes 21 and 22 can be obtained by performing a drying treatment, a heat treatment, or a firing treatment as necessary. In this case, as a method for applying the mixture onto the insulating surface 13, for example, a known coating method such as a spin coating method or a spray coating method, or a screen printing method using a plate making in which the electrodes 21 and 22 are patterned is used. Can be applied. In applying or printing the mixture, for example, a known coating device such as a spin coater or a slit coater or a known printing device can be used. Furthermore, the size of the electrodes 21 and 22, the size of the gap between the electrodes 21 and 22, and the gap distance ΔG can be processed using a known method such as ion milling or etching. In addition, although the processing conditions at the time of baking are not specifically limited, When productivity and economical efficiency are considered, about 10 minutes-about 5 hours are preferable at 500-1200 degreeC by an atmospheric condition.

  A discharge inducing portion 31 is disposed between the gaps between the electrodes 21 and 22. In the present embodiment, the discharge inducing portion 31 is configured to be laminated between the insulating substrate 12d and the insulating substrate 12e so as to be disposed between the gaps between the electrodes 21 and 22. The size and shape of the discharge inducing portion 31 and the arrangement position thereof are particularly limited as long as the initial discharge is secured between the gaps of the electrodes 21 and 22 through itself when an overvoltage is applied. Not.

The material constituting the discharge inducing portion 31 is not particularly limited as long as the material is designed so that initial discharge is secured between the electrodes 21 and 22 through itself when an overvoltage is applied. Examples of the electrostatic protection material that can be discharged even at a relatively low voltage include, for example, insulating organic materials such as Al ₂ O ₃ , TiO ₂ and SiO ₂ , metal oxides such as forsterite and metal nitrides, and metal nitrides. A composite or the like in which a conductive inorganic material is discontinuously contained (uniformly or randomly dispersed) in a matrix of the material and / or an insulating inorganic material is known.

  In the present embodiment, the discharge inducing portion 31 is a composite in which a conductive inorganic material is discontinuously (uniformly or randomly) dispersed in a matrix of an insulating inorganic material. In other words, the discharge inducing portion 31 has a so-called sea-island structure in which aggregates of conductive inorganic materials are discontinuously scattered in a matrix of insulating inorganic materials. By adopting such a composite as the discharge inducing portion 31, it is possible to reduce the capacitance. In addition, this composite is easier to make thinner than conventional discharge inducing parts, and is superior in durability and heat resistance compared to the case of using an organic material. Furthermore, temperature, humidity, etc. Excellent weather resistance to the external environment.

Specific examples of the insulating inorganic material constituting the matrix include, but are not limited to, metal nitrides such as metal oxides and forsterite. In consideration of insulation and cost, Al ₂ O ₃ , SrO, CaO, BaO, TiO ₂ , SiO ₂ , ZnO, In ₂ O ₃ , NiO, CoO, SnO ₂ , Bi ₂ O ₃ , Mg ₂ SiO ₄ , V ₂ O ₅ , CuO, MgO, ZrO ₂ , AlN, BN and SiC are preferable. These may be used alone or in combination of two or more. The matrix of the insulating inorganic material may be formed as a uniform film of the insulating inorganic material or may be formed as an aggregate of particles of the insulating inorganic material, and the properties thereof are not particularly limited. Among these, it is more preferable to use Al ₂ O ₃ , SiO ₂ , forsterite or the like from the viewpoint of imparting a high degree of insulation to the insulating matrix. On the other hand, from the viewpoint of imparting semiconductivity to the insulating matrix, it is more preferable to use TiO ₂ or ZnO. By imparting semiconductivity to the insulating matrix, it is possible to obtain an anti-static element having excellent discharge start voltage and clamp voltage. Here, the method for imparting semiconductivity to the insulating matrix is not particularly limited. For example, these TiO ₂ and ZnO may be used alone, or these may be used in combination with other insulating inorganic materials.

  Specific examples of the conductive inorganic material include, but are not particularly limited to, metals, alloys, metal oxides, metal nitrides, metal carbides, metal borides, and the like. In consideration of conductivity, C, Ni, Al, Fe, Cu, Ti, Cr, Au, Ag, Pd and Pt, or alloys thereof are preferable.

  The thickness of the discharge induction part 31 is not specifically limited, It can set suitably. Specifically, the thickness is preferably 10 nm to 60 μm, and more preferably 100 nm to 50 μm.

  The formation method of the discharge induction part 31 is not specifically limited, A well-known thin film formation method is applicable. From the viewpoint of easily obtaining a high-performance discharge inducing portion 31 with good reproducibility, a method of firing after applying the above-described mixture containing at least the insulating inorganic material and the conductive inorganic material is suitable. Hereinafter, a preferable method for forming the discharge inducing portion 31 will be described.

  In this method, a mixture containing at least an insulating inorganic material and a conductive inorganic material is prepared, and this mixture is applied or printed between at least the gaps between the electrodes 21 and 22, and then baked. In addition, you may mix | blend various additives, such as a solvent and a binder, in the case of preparation of a mixture, or the application or printing of a mixture. Moreover, the treatment conditions at the time of baking are not particularly limited, but considering productivity and economy, it is preferably about 10 minutes to 5 hours at 500 to 1200 ° C. in an air atmosphere.

  In the electrostatic protection element 100 of this embodiment, the discharge inducing part 31 that is a composite in which a conductive inorganic material is discontinuously dispersed in a matrix of an insulating inorganic material can be discharged at a relatively low voltage. Function as. Moreover, since the discharge inducing part 31 containing a conductive metal oxide has an excellent balance of conductivity, heat resistance, and mechanical strength, the electrode due to heat and stress generated by discharge without excessively impairing conductivity (discharge property). (Disintegration, deformation, dropout, etc.) is mitigated and the occurrence of a short circuit between the electrodes 21 and 22 after discharge is suppressed. Therefore, the anti-static element 100 of the present embodiment has a small electrostatic capacity and excellent discharge characteristics and durability during repeated use. In addition, since the discharge inducing portion 31 is made of a composite made of an inorganic material, the heat resistance is improved, and the characteristics hardly change depending on the external environment such as temperature and humidity. As a result, the reliability is improved. It is done.

(Second Embodiment)
FIG. 2 is a schematic cross-sectional view schematically showing the antistatic element of the present embodiment.
The electrostatic protection element 200 changes the shape of the electrodes 21 and 22 to an L shape as shown in the figure, and electrically connects the electrodes 21 and 22 and the terminal electrode 41 via the lead electrodes 51 and 52. The configuration is the same as that of the anti-static element 100 of the first embodiment except that the above is changed.

  That is, the anti-static element 200 includes an insulating laminate 11, a pair of L-shaped electrodes 21 and 22 that are spaced apart from each other in the insulating laminate 11, and the electrodes 21 and 22. The discharge inducing portion 31 disposed in the gap located between them, the rectangular lead electrodes 51 and 52 electrically connected to the electrodes 21 and 22, and the lead electrodes 51 and 52 are electrically connected. Terminal electrode 41 (see FIG. 9) (not shown). The electrostatic protection element 200 is produced by a lamination method, and a pair of electrodes 21 and 22 are embedded in the insulating laminate 11. In the electrostatic protection element 200, the electrodes 21 and 22 are electrically connected to an external circuit via the lead electrodes 41 and 42 and the terminal electrode 41, and the discharge inducing portion 31 can be discharged even at a relatively low voltage. It functions as a low-voltage discharge type electrostatic protection material, and is designed to ensure initial discharge between the electrodes 21 and 22 via the discharge inducing portion 31 when an overvoltage such as static electricity is applied from the outside.

The lead electrodes 51 and 52 are made of a material having a resistivity of less than 10 ⁻⁷ Ωm and excellent conductivity. Specific examples of the material constituting the lead electrodes 51 and 52 include, for example, metals, alloys, metal oxides, metal nitrides, metal carbides, metal borides and the like, but are not particularly limited thereto. In consideration of conductivity, C, Ni, Al, Fe, Cu, Ti, Cr, Au, Ag, Pd and Pt, or alloys thereof are preferable. In the present embodiment, the lead electrodes 21 and 22 are formed in a rectangular shape in plan view, but the shape is not particularly limited.

  When the electrodes 21 and 22 are arranged on the lead electrodes 51 and 52 as in this embodiment, the length of the electrodes 21 and 22 (in FIG. The direction) is preferably equal to or greater than the length exceeding the overlapping portion of the lead electrodes 51 and 52 in a plan view, and is 1.2 times or more the length exceeding the overlapping portion of the lead electrodes 51 and 52 in a plan view. It is more preferable.

  The formation method of the lead electrodes 51 and 52 is not specifically limited, A well-known method can be selected suitably. Specifically, for example, the lead electrodes 51 and 52 having a desired thickness are patterned on the insulating surface 13 facing the insulating substrates 12d and 12e by coating, transferring, electrolytic plating, electroless plating vapor deposition, sputtering, or the like. The method of forming is mentioned. In addition, the size and shape of the lead electrodes 51 and 52 can be processed using a known method such as ion milling or etching.

  The electrostatic countermeasure element 200 having the lead electrodes 51 and 52 arranged in this way also has the same effects as the electrostatic countermeasure element 100 of the first embodiment. In addition, lead electrodes 51 and 52 having excellent conductivity are arranged to reduce the use ratio of the relatively high resistance electrodes 21 and 22 in the discharge path, so that the resistance value of the entire element can be lowered and the discharge can be performed. The amount of heat generated at the time can be reduced, and the discharge characteristics and durability during repeated use can be further enhanced.

(Third embodiment)
FIG. 3 is a schematic cross-sectional view schematically showing the antistatic element of this embodiment.
In the electrostatic protection element 300, the arrangement position of the pair of electrodes 21 and 22 is changed to an insulating substrate 12d as shown in the figure, and a gap is formed between the pair of electrodes 21 and 22 formed on the insulating substrate 12d. The configuration is the same as that of the anti-static element 100 of the first embodiment except that is provided.

  That is, the electrostatic protection element 300 includes an insulating laminate 11, a pair of rectangular electrodes 21 and 22 that are disposed to be opposed to each other in the insulating laminate 11, and between the electrodes 21 and 22. And a discharge inducing portion 31 disposed in the gap, and a terminal electrode 41 (not shown) electrically connected to the electrodes 21 and 22. The electrostatic protection element 300 is produced by a lamination method, and has a form in which a pair of electrodes 21 and 22 are embedded in the insulating laminate 11. In this electrostatic protection element 300, the electrodes 21 and 22 are electrically connected to an external circuit through the terminal electrode 41, and the discharge inducing portion 31 functions as an electrostatic protection material that can be discharged even at a relatively low voltage. It is designed such that initial discharge is secured between the electrodes 21 and 22 via the discharge inducing portion 31 when an overvoltage such as static electricity is applied from the outside.

  The electrostatic countermeasure element 200 having the electrodes 21 and 22 arranged in this way also has the same effects as the electrostatic countermeasure element 100 of the first embodiment.

(Fourth embodiment)
FIG. 4 is a schematic cross-sectional view schematically showing the antistatic element of the present embodiment.
The electrostatic protection element 400 changes the shape of the electrodes 21 and 22 to a stepped shape (stepped shape) as shown in the figure, and electrically connects the electrodes 21 and 22 and the terminal electrode 41 via the lead electrodes 51 and 52. The configuration is the same as that of the antistatic element 300 of the third embodiment except that the connection is changed so as to be connected.

  That is, the antistatic element 400 includes an insulating laminate 11, a pair of stepped (stepped) electrodes 21, 22 disposed opposite to each other in the insulating laminate 11, and the electrodes 21. , 22, the discharge inducing portion 31 disposed in the gap, the rectangular lead electrodes 51, 52 electrically connected to the electrodes 21, 22, and the lead electrodes 51, 52 electrically And a terminal electrode 41 (see FIG. 12) not shown. The electrostatic protection element 200 is produced by a lamination method, and a pair of electrodes 21 and 22 are embedded in the insulating laminate 11. In this anti-static element 200, the electrodes 21 and 22 are electrically connected to an external circuit via the lead electrodes 41 and 42 and the terminal electrode 41, and the discharge inducing portion 31 functions as an electrostatic protection material, such as static electricity. When an overvoltage is applied from the outside, an initial discharge is secured between the electrodes 21 and 22 via the discharge inducing portion 31.

  When the electrodes 21 and 22 are arranged between the lead electrodes 51 and 52 as in the present embodiment, the electrodes 21 and 22 are at least end faces of the lead electrodes 51 and 52 from the viewpoint of suppressing discharge between the lead electrodes 51 and 52. It is preferably formed so as to cover (the surface facing the gap), and more preferably formed so as to cover the end surfaces of the lead electrodes 51 and 52 and the top surfaces of the lead electrodes 51 and 52.

  Thus, the electrostatic countermeasure element 400 provided with the electrodes 21 and 22 and the lead electrodes 51 and 52 has the same effects as the electrostatic countermeasure element 300 of the third embodiment. In addition, lead electrodes 51 and 52 having excellent conductivity are arranged to reduce the use ratio of the relatively high resistance electrodes 21 and 22 in the discharge path, so that the resistance value of the entire element can be lowered and the discharge can be performed. The amount of heat generated at the time can be reduced, and the electrostatic capacity is reduced, so that the discharge characteristics and durability during repeated use can be further improved.

(Modification)
The present invention can be variously modified without departing from the gist thereof, and is not limited to the first to fourth embodiments described above. For example, as shown in FIG. 5, the electrodes 21 and 22 may be formed so as to cover substantially the entire surface of the lead electrodes 51 and 52. Moreover, as shown in FIG. 6, the electrodes 21 and 22 may have an accumulation structure of conductive metal oxide particles.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.

First, La substituted CaMnO ₃ which is a conductive metal oxide was prepared by the following procedure.
La-substituted CaMnO ₃ was synthesized using a solid phase reaction method. Here, first, CaCO ₃ , Mn ₃ O ₄ , and La (OH) ₃ were weighed so as to have a predetermined molar ratio, and wet-mixed by a ball mill using water as a medium. In the wet mixing, zirconia balls were used as the grinding media. Next, the obtained slurry was dried and pulverized to an appropriate particle size, and then calcined in the atmosphere at 1000 to 1250 ° C. for 2 hours to obtain La-substituted CaMnO ₃ (calcined powder). About the obtained calcined powder, when the phase identification by XRD was performed, it confirmed that a production | generation layer was a single phase. Furthermore, the obtained calcined powder was wet pulverized using water as a medium. In the wet mixing, zirconia balls were used as the grinding media. By crushing and drying the resulting slurry to give La-substituted CaMnO ₃ is an object (finished material).

Next, Al-substituted ZnO, which is a conductive metal oxide, was prepared by the following procedure.
First, ZnO and Al ₂ O ₃ were weighed so as to have a predetermined molar ratio, and wet mixed by a ball mill using water as a medium. In the wet mixing, zirconia balls were used as the grinding media. Next, the obtained slurry was dried and pulverized to an appropriate particle size, and then calcined in the atmosphere at 1000 to 1200 ° C. for 2 hours to obtain Al-substituted ZnO (calcined powder). Furthermore, the obtained calcined powder was wet pulverized using water as a medium. In the wet mixing, zirconia balls were used as the grinding media. And the target Al substituted ZnO (finished material) was obtained by drying and crushing the obtained slurry.

Next, NiO.Fe ₂ O ₃ which is a conductive metal oxide was prepared by the following procedure.
First, NiO and Fe ₂ O ₃ were weighed so as to have a predetermined molar ratio, and wet mixed by a ball mill using water as a medium. In the wet mixing, zirconia balls were used as the grinding media. Next, the obtained slurry was dried and crushed to an appropriate particle size, and then heat-treated at 1000 to 1200 ° C. for 2 hours in the air, and then heat-treated at 1200 to 1300 ° C. again in a nitrogen atmosphere. By performing, calcined powder was obtained. Further, the obtained calcined powder was wet pulverized using water as a medium. In the wet mixing, zirconia balls were used as the grinding media. By crushing and drying the resulting slurry to obtain NiO · Fe ₂ O ₃ for the purpose of (finished material).

  The resistivity of each conductive metal oxide (finished material) prepared as described above was measured by the following procedure. First, a rod-shaped molded body is prepared by adding a binder to a conductive metal oxide (finished material), and the resulting molded body is sintered at a predetermined temperature for 2 hours to produce a rod-shaped sintered body. did. After measuring the dimensions of the obtained sintered body, Ag was baked on both ends of the obtained sintered body to form terminals, and then resistance measurement was performed by the 4-terminal method to calculate the resistivity.

Example 1
First, as an insulating substrate 12 (12a, 12b, 12c, 12d, 12e, 12f, 12g, 12h), a green sheet (TDK Corporation) in which a material composed mainly of Al ₂ O ₃ and a glass component is formed into a sheet. Prepared). This green sheet is prepared by adjusting the Al ₂ O ₃ , glass component and sintering aid so as to have a predetermined ratio, adding a binder and an organic solvent to form a slurry, and then using a doctor blade method. It is a sheet.

Next, as shown in FIG. 7, an Ag paste layer (a precursor of the lead electrodes 51 and 52) and a conductive metal oxide paste layer (the electrodes 21 and 22) are formed on the insulating surface 13 of the insulating substrates 12d and 12e. The precursor was patterned by the following procedure.
A silver paste (manufactured by Shoei Chemical Industry Co., Ltd.) is screen-printed on the insulating surfaces 13 of the insulating substrates 12d and 12e, and then dried by heating, whereby a length of 0.5 mm having a structure equivalent to that shown in FIG. A strip-shaped Ag paste layer (a precursor of the lead electrodes 51 and 52) having a width of 0.4 mm and a thickness of 20 μm was formed in a pattern.
Next, La-substituted CaMnO having an average particle size of 0.6 μm prepared as described above was prepared in a lacquer prepared by kneading ethyl cellulose resin as a binder and terpineol as a solvent so that the solid content ratio was 8 wt%. ₃ (finished material) was blended so that the solid content ratio of La-substituted CaMnO ₃ was 70 vol%, and the mixture was kneaded to prepare a conductive metal oxide paste. The obtained conductive metal oxide paste is screen-printed on the insulating surface 13 of the insulating substrates 12d and 12e and on the Ag paste layer (precursor of the lead electrodes 51 and 52), and then dried by heating. A L-shaped conductive metal oxide paste layer (a precursor of the electrodes 21 and 22) having a structure equivalent to that shown in FIG. 7 and having a length of 60 μm, a width of 0.4 mm, and a thickness of 10 μm was formed in a pattern.

Thereafter, as shown in FIG. 8, the insulating substrates 12d and 12e on which the Ag paste layer (precursor of the lead electrodes 51 and 52) and the conductive metal oxide paste layer (precursor of the electrodes 21 and 22) are patterned are formed. And the insulating substrates 12a, 12b, 12c, 12f, 12g, and 12h, and the discharge inducing portion paste layer (precursor of the discharge inducing portion 13) are laminated in the following procedure, whereby the insulating laminate 11 is formed. The stack body was formed.
First, glass particles containing SiO ₂ as a main component as an insulating inorganic material (manufactured by Yamamura Glass Co., Ltd., product number: ME13) are 70 vol%, and Ag particles having an average particle diameter of 1 μm as conductive inorganic materials (Mitsui Mining & Smelting Co., Ltd. Company product, product number: SPQ05S) was weighed to be 30 vol%, and these were mixed to obtain a mixture. And the lacquer prepared by kneading ethyl cellulose resin as a binder and terpineol as a solvent so that the solid content ratio is 8 wt%, and the resulting mixture so that the solid content ratio of the mixture is 60 vol% The discharge induction part paste was prepared by mix | blending and knead | mixing the mixture.
The obtained discharge inducing portion paste is formed on the insulating substrates 12d and 12e on which the Ag paste layer (precursor of the lead electrodes 51 and 52) and the conductive metal oxide paste layer (precursor of the electrodes 21 and 22) are patterned. After screen printing on each of them, the insulating substrates 12d and 12e are bonded together, and further, the insulating substrates 12a, 12b, 12c, 12f, 12g, and 12h are laminated and hot-pressed, whereby the discharge inducing portion paste layer ( A precursor having a structure equivalent to that shown in FIG. 8 was prepared.

The obtained stack was cut into a predetermined size and separated into individual pieces. Thereafter, the individualized stack was subjected to heat treatment (debinding treatment) at 200 ° C. for 1 hour, and then heated at 10 ° C. per minute and held at 950 ° C. for 30 minutes in the atmosphere. By this baking treatment, the electrodes 21 and 22, the discharge inducing portion 31, and the lead electrodes 51 and 52 having a resistivity of less than 10 ⁻⁷ are manufactured. The gap distance ΔG between the pair of electrodes 21 and 22 after firing was about 20 μm.

  Thereafter, as shown in FIG. 9, a terminal electrode 41 mainly composed of Ag is formed so as to be connected to the outer peripheral ends of the lead electrodes 51 and 52 of the stack body after sintering, as shown in FIG. An antistatic element 200 of Example 1 having a structure equivalent to that of the device was obtained.

(Example 2)
The same operation as in Example 1 is performed except that the electrodes 21 and 22, the discharge inducing portion 31, and the lead electrodes 51 and 52 are prepared in the following procedure to produce a stack body, which is the same as that shown in FIG. 4. An antistatic element 400 of Example 2 having the structure was obtained.
The above Ag paste is screen-printed on the insulating surface 13 of the insulating substrate 12d, and then heated and dried, so that it has a structure equivalent to that shown in FIG. A band-shaped Ag paste layer (precursor of the lead electrodes 51 and 52) having a thickness of 20 μm was patterned.
Next, the conductive metal oxide paste is screen-printed on the insulating surface 13 of the insulating substrate 12d and on the Ag paste layer (precursor of the lead electrodes 51 and 52), and then dried by heating. Step-forming (step-like) conductive metal oxide paste layers (precursors of electrodes 21 and 22) each having a structure equivalent to that shown in FIG. 10 having a length of 60 μm, a width of 0.4 mm, and a thickness of 10 μm are pattern-formed. did.
Thereafter, as shown in FIG. 11, an insulating substrate 12d on which an Ag paste layer (a precursor of lead electrodes 51 and 52) and a conductive metal oxide paste layer (a precursor of electrodes 21 and 22) are patterned, Insulating substrate 12a, 12b, 12c, 12e, 12f, 12g, 12h and discharge inducing part paste layer (precursor of discharge inducing part 13) are laminated in the following procedure, whereby insulating laminate 11 is formed. The stack body was formed.
The discharge inducing portion paste is screened on an insulating substrate 12d on which an Ag paste layer (precursor of lead electrodes 51 and 52) and a conductive metal oxide paste layer (precursor of electrodes 21 and 22) are patterned. After printing, the insulating substrates 12d and 12e are bonded together, and further, the insulating substrates 12a, 12b, 12c, 12f, 12g, and 12h are laminated and hot-pressed to thereby form a discharge inducing portion paste layer (discharge inducing portion 31). And a stack having a structure equivalent to that shown in FIG. 11 was produced.

The obtained stack was cut into a predetermined size and separated into individual pieces. Thereafter, the individualized stack was subjected to heat treatment (debinding treatment) at 200 ° C. for 1 hour, and then heated at 10 ° C. per minute and held at 950 ° C. for 30 minutes in the atmosphere. By this baking treatment, the electrodes 21 and 22, the discharge inducing portion 31, and the lead electrodes 51 and 52 having a resistivity of less than 10 ⁻⁷ are manufactured. The gap distance ΔG between the pair of electrodes 21 and 22 after firing was about 30 μm.

  Then, as shown in FIG. 12, the terminal electrode 41 mainly composed of Ag is formed so as to be connected to the outer peripheral ends of the lead electrodes 51 and 52 of the stack body after sintering, as shown in FIG. An antistatic element 400 of Example 2 having a structure equivalent to that of Example 1 was obtained.

(Example 3)
The same operation as in Example 1 was performed except that a conductive metal oxide paste containing Al-substituted ZnO was used instead of the conductive metal oxide paste containing La-substituted CaMnO ₃ , and the same as shown in FIG. An antistatic element 200 of Example 3 having the structure was obtained. The conductive metal oxide paste containing Al-substituted ZnO used here is a lacquer prepared by kneading ethyl cellulose resin as a binder and terpineol as a solvent so that the solid content ratio is 8 wt%. The Al-substituted ZnO (finished material) having an average particle diameter of 0.6 μm prepared as described above was blended so that the solid content ratio of the Al-substituted ZnO was 60 vol%, and the mixture was kneaded and prepared. is there.

Example 4
Except for setting the gap distance ΔG between the electrodes 21 and 22 to about 30 μm, the same operation as in Example 3 was performed to obtain the electrostatic protection element 200 of Example 4 having the same structure as that shown in FIG. .

(Example 5)
FIG. 2 shows the same operation as in Example 1 except that a conductive metal oxide paste containing NiO.Fe ₂ O ₃ is used instead of the conductive metal oxide paste containing La-substituted CaMnO ₃ . An antistatic element 200 of Example 5 having a structure equivalent to that of Example 1 was obtained. The conductive metal oxide paste containing NiO.Fe ₂ O ₃ used here is a lacquer prepared by kneading ethyl cellulose resin as a binder and terpineol as a solvent so that the solid content ratio is 8 wt%. The NiO.Fe ₂ O ₃ (finished material) having an average particle diameter of 0.6 μm prepared as described above was blended so that the solid content ratio of NiO.Fe ₂ O ₃ was 60 vol%, and the mixture was mixed. It is prepared by kneading.

(Example 6)
Except for setting the gap distance ΔG between the electrodes 21 and 22 to about 30 μm, the same operation as in Example 5 was performed to obtain an electrostatic protection element 200 of Example 6 having the same structure as that shown in FIG. .

(Example 7)
Except for setting the gap distance ΔG between the electrodes 21 and 22 to about 40 μm, the same operation as in Example 1 was performed to obtain the electrostatic protection element 200 of Example 7 having the same structure as that shown in FIG. .

(Example 8)
Except for setting the gap distance ΔG between the electrodes 21 and 22 to about 50 μm, the same operation as in Example 2 was performed to obtain an electrostatic protection element 400 of Example 8 having a structure equivalent to that shown in FIG. .

(Comparative Example 1)
An electrostatic protection device of Comparative Example 1 was obtained in the same manner as in Example 1 except that the formation of the conductive metal oxide paste layers (precursors of electrodes 21 and 22) and electrodes 21 and 22 were omitted. .

(Comparative Example 2)
An electrostatic protection device of Comparative Example 2 was obtained by operating in the same manner as in Example 2 except that the formation of the conductive metal oxide paste layers (precursors of electrodes 21 and 22) and electrodes 21 and 22 were omitted. .

(Comparative Example 3)
Instead of the conductive metal oxide paste containing La-substituted CaMnO ₃ , the tungsten oxide electrodes 21 and 22 are produced using an insulating metal oxide paste containing tungsten powder, as in Example 1. The antistatic element of Comparative Example 3 was obtained by operating. The insulating metal oxide paste containing tungsten powder used here has an average particle size of lacquer prepared by kneading ethyl cellulose resin as a binder and terpineol as a solvent so that the solid content ratio is 8 wt%. A tungsten oxide powder having a diameter of 0.6 μm was prepared by blending so that the solid content ratio of the tungsten powder was 60 vol%, and kneading the mixture.

(Comparative Example 4)
The antistatic device of Comparative Example 4 was operated in the same manner as in Example 1 except that an insulating metal oxide paste containing alumina powder was used instead of the conductive metal oxide paste containing La-substituted CaMnO _3. Got. The insulating metal oxide paste containing the alumina powder used here has an average particle size in a lacquer prepared by kneading ethyl cellulose resin as a binder and terpineol as a solvent so that the solid content ratio is 8 wt%. An alumina powder having a diameter of 0.6 μm was blended so that the solid content ratio of the alumina powder was 60 vol%, and the mixture was kneaded and prepared.

<Electrostatic discharge test>
Next, the electrostatic discharge test was implemented about the static electricity countermeasure element of Examples 1-8 obtained as mentioned above and Comparative Examples 1-4 using the electrostatic test circuit shown in FIG. Table 1 shows the test results.

  This electrostatic discharge test was performed in accordance with a human body model (discharge resistance 330Ω, discharge capacity 150 pF, applied voltage 8 kV, contact discharge) based on the electrostatic discharge immunity test and noise test of the international standard IEC61000-4-2. Specifically, as shown in the electrostatic test circuit of FIG. 13, one terminal electrode of the electrostatic countermeasure element to be evaluated is grounded, and an electrostatic pulse applying unit is connected to the other terminal electrode, An electrostatic pulse was applied by bringing a discharge gun into contact with the application section. Note that the discharge start voltage was a voltage at which an electrostatic absorption effect appeared in an electrostatic absorption waveform observed when the electrostatic test was performed while increasing the interval from 0.4 kV to 0.2 kV. Moreover, the electrostatic capacitance was the electrostatic capacitance (pF) at 1 MHz. Furthermore, regarding the discharge resistance, 100 samples were prepared for each, and when the electrostatic discharge test was repeated 100 times each at 8.0 kV, the number of short-circuits between the electrodes was counted and evaluated by the size of the number. .

  From the results shown in Table 1, it was confirmed that the anti-static elements of Examples 1 to 8 had a low discharge start voltage and a low capacitance, and had high performance applicable in a high-speed transmission system. . Furthermore, it is confirmed that the anti-static elements of Examples 1 to 8 are extremely suppressed from occurrence of short circuit between the electrodes, the durability of repeated use is enhanced, and the reliability is excellent. Was confirmed.

On the other hand, from the results shown in Table 1, it was confirmed that the antistatic elements of Comparative Example 1 and Comparative Example 2 had many short circuits between the electrodes and were inferior in durability for repeated use. For this reason, an electrode containing a conductive metal oxide is not formed, and a mode in which a discharge is generated between metal electrodes that are lead electrodes having a resistivity of less than 10 ⁻⁷ is the heat and stress generated by the discharge. This suggests that the electrodes are easily broken, and therefore, a short circuit between the metal electrodes is likely to occur.

On the other hand, from the results shown in Table 1, the anti-static elements of Comparative Example 3 and Comparative Example 4 have a high discharge start voltage, a large number of short circuits between the electrodes, and are inferior in durability for repeated use. Was confirmed. From this, the metal electrode, which is a lead electrode having a resistivity of less than 10 ⁻⁷ , is coated with an insulating metal oxide having a resistivity of more than 10 ^5, and the conductivity (discharge property) of the electrode is excessive. It is suggested that it will be damaged. Further, even when a metal electrode having a resistivity of less than 10 ⁻⁷ is coated with an insulating metal oxide having a resistivity of more than 10 ⁵ , the electrode is still liable to be broken by heat and stress generated by the discharge. It is suggested that a short circuit occurs easily.

  As described above, the anti-static element of the present invention has improved discharge characteristics and durability for repeated use, and can further reduce heat capacity and heat resistance and weather resistance. Since it has the feature that productivity and economy can be further improved, it can be widely and effectively used for electronic / electrical devices equipped with them and various devices, facilities, systems, etc. equipped with them.

  DESCRIPTION OF SYMBOLS 11 ... Insulating laminated body, 21, 22 ... Electrode, 31 ... Discharge induction part, 51, 52 ... Lead electrode, 100, 200, 300, 400 ... Electrostatic countermeasure element, (DELTA) G ... Gap distance .

Claims (9)

An insulating laminate, electrodes disposed opposite to each other in the insulating laminate, a gap positioned between the electrodes, and at least a discharge inducing portion disposed in the gap,
The electrode includes a conductive metal oxide,
Antistatic element. The conductive metal oxide has a resistivity of 10 ⁻⁷ Ωm or more and 10 ⁵ Ωm or less.
The antistatic element according to claim 1. The conductive metal oxide is a sintered body.
The antistatic element according to claim 1 or 2. The conductive metal oxide is a particle,
The electrode has an integrated structure of the conductive metal oxide particles;
The static electricity countermeasure element as described in any one of Claims 1-3. The gap distance ΔG between the electrodes is 70 μm or less.
The static electricity countermeasure element as described in any one of Claims 1-4. Furthermore, a lead electrode having a resistivity of less than 10 ⁻⁷ Ωm is provided,
The electrode is electrically connected to an external circuit through the lead electrode.
The antistatic element as described in any one of Claims 1-5. The discharge inducing portion is a composite in which a conductive inorganic material is discontinuously dispersed in a matrix of an insulating inorganic material.
The static electricity countermeasure element as described in any one of Claims 1-6. The insulating inorganic material includes Al ₂ O ₃ , SrO, CaO, BaO, TiO ₂ , SiO ₂ , ZnO, In ₂ O ₃ , NiO, CoO, SnO ₂ , Mg ₂ SiO ₄ , V ₂ O ₅ , CuO, It is at least one selected from the group consisting of MgO, ZrO ₂ , Bi ₂ O ₃ , AlN, BN and SiC,
The antistatic element according to claim 7.   The conductive inorganic material is at least one metal selected from the group consisting of C, Ni, Al, Fe, Cu, Ti, Cr, Au, Ag, Pd, and Pt, or a metal compound thereof. Or the antistatic element of 8.

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