Transient Voltage Protection Components

Abstract

To provide a transient voltage protection component capable of suppressing short circuit and having an excellent ESD (Electro-Static Discharge) resistance.SOLUTION: Provided is a transient voltage protection component that has: a pair of discharge electrodes opposed to each other via a gap; and a discharge induction part adjacent to the pair of discharge electrodes. The discharge induction part has: a base material containing glass; and a plurality of metal particles dispersed in the base material. The glass contains SiO2, TiO2, and an alkali earth metal component.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to transient voltage protection components. [Background technology]

[0002] A known transient voltage protection component has a pair of opposing discharge electrodes and a discharge inducing part adjacent to the discharge electrodes, as shown in Patent Document 1. This transient voltage protection component protects circuits from ESD (Electro-Static Discharge) and prevents damage to and malfunction of electronic devices due to ESD.

[0003] The discharge triggering section contains both ceramic and metallic materials, and increasing the metallic content in the discharge triggering section is expected to improve the ESD absorption effect. However, if the metallic content is high, a pair of discharge electrodes may short-circuit through the discharge triggering section. Therefore, there is a need to develop technology that can achieve high ESD resistance while suppressing the occurrence of short-circuits. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO 2009 / 098944 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a transient voltage protection component that can suppress short circuits and has excellent ESD resistance. [Means for solving the problem]

[0006] In order to achieve the above object, the transient voltage protection component according to the present invention comprises: a pair of discharge electrodes facing each other across a gap; a discharge inducing unit adjacent to the pair of discharge electrodes, the discharge inducing unit has a base material containing glass and a plurality of metal particles dispersed in the base material, The glass includes SiO2, TiO2, and an alkaline earth metal component.

[0007] The transient voltage protection component of the present invention has the above-mentioned characteristics, which enable the density of the discharge inducing portion to be increased while suppressing the grain growth of the metal particles, thereby preventing the occurrence of short circuits and achieving high ESD resistance.

[0008] The glass may contain B2O3.

[0009] Preferably, the base material of the discharge triggered part contains zirconia, a non-glass material. The inclusion of zirconia in the discharge triggered part can more effectively suppress grain growth of metal particles and further improve ESD resistance. Furthermore, the inclusion of zirconia in the discharge triggered part can improve adhesion between the discharge triggered part and the insulator layer in contact with the discharge triggered part.

[0010] Preferably, the content of TiO2 in the substrate is 0.05 wt% or more and 10 wt% or less with respect to 100 wt% of the substrate.

[0011] Preferably, the Si / Ti ratio in the substrate is 5 or more.

[0012] Preferably, the content of the alkali metal component in the base material is 2 wt % or less relative to 100 wt % of the base material.

[0013] As described above, when the glass of the discharge inducing portion has a predetermined composition, the grain growth of metal particles can be more effectively suppressed and the ESD resistance can be further improved. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view showing a transient voltage protection component according to one embodiment of the present invention. [Figure 2A] FIG. 2A is a cross-sectional view taken along line IIA-IIA shown in FIG. [Figure 2B] FIG. 2B is a cross-sectional view taken along line IIB-IIB shown in FIG. [Figure 3] FIG. 3 is an enlarged cross-sectional view of the discharge inducing portion. [Figure 4] FIG. 4 is a plan view of a green sheet used in the manufacturing process of a transient voltage protection component. [Figure 5] FIG. 5 is an exploded perspective view of a green chip used in the manufacturing process of a transient voltage protection component. [Figure 6A] FIG. 6A is a cross-sectional view showing a modified example of a transient voltage protection component. [Figure 6B] FIG. 6B is a cross-sectional view showing a modified example of the transient voltage protection component. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described in detail below with reference to the embodiments shown in the drawings. As shown in Figure 1, a transient voltage protection component 2 according to this embodiment has an element body 10 having a substantially rectangular parallelepiped shape (substantially hexahedron) and a pair of external electrodes (a first external electrode 6 and a second external electrode 8) formed on the outer surface of the element body 10.

[0016] The element body 10 has a pair of end faces 10a that are substantially perpendicular to the X-axis, a pair of side faces 10b that are substantially perpendicular to the Y-axis, and a pair of main faces 10c that are substantially perpendicular to the Z-axis. The dimensions of the element body 10 are not particularly limited and may be set to appropriate dimensions depending on the application. In this embodiment, the X-axis, Y-axis, and Z-axis are perpendicular to each other.

[0017] The first external electrode 6 covers one end face 10a and is formed to extend from this end face 10a around the side face 10b and part of the main face 10c. The second external electrode 8 covers the other end face 10a and is formed to extend from this end face 10a around the side face 10b and part of the main face 10c. The first external electrode 6 and the second external electrode 8 are insulated so as not to contact each other in the X-axis direction.

[0018] 2A is an XZ cross section of the transient voltage protection component 2 taken at approximately the center in the Y-axis direction. Meanwhile, FIG. 2B is an XY cross section of the transient voltage protection component 2 taken at approximately the center in the Z-axis direction. As shown in FIGS. 2A and 2B, the element body 10 has multiple insulator layers 11, a pair of discharge electrodes (first discharge electrode 16 and second discharge electrode 18), a discharge inducing portion 13, and a hollow portion 15.

[0019] The multiple insulator layers 11 are all sintered bodies having electrical insulation properties and are stacked along the Z-axis direction. The insulator layers 11 are integrated to the extent that the boundaries between the layers are not visible. The thickness of the insulator layers 11 and the number of layers are not particularly limited and may be determined appropriately depending on the dimensions of the element body 10.

[0020] The first discharge electrode 16 and the second discharge electrode 18 are both electrode layers having a rectangular shape in a planar view and are interposed between predetermined insulator layers 11. The thicknesses of the first discharge electrode 16 and the second discharge electrode 18 are not particularly limited, but it is preferable that the first discharge electrode 16 and the second discharge electrode 18 have approximately the same average thickness. Furthermore, the first discharge electrode 16 and the second discharge electrode 18 are both stacked on the same insulator layer 11, and the distance in the Z-axis direction from the main surface 10c to the first discharge electrode 16 is approximately the same as the distance in the Z-axis direction from the main surface 10c to the second discharge electrode 18. That is, the first discharge electrode 16 and the second discharge electrode 18 are located at approximately the same height in the Z-axis direction. However, the first discharge electrode 16 and the second discharge electrode 18 are arranged at a distance from each other so as not to come into direct contact in the X-axis direction.

[0021] The first discharge electrode 16 has a lead portion 16a and a facing portion 16b. The lead portion 16a is the end of the first discharge electrode 16 facing outward in the X-axis direction. This lead portion 16a is exposed at the end surface 10a of the element body 10 and is electrically connected to the external electrode 6. On the other hand, the facing portion 16b is the end of the first discharge electrode 16 facing inward in the X-axis direction. This facing portion 16b is located inside the hollow portion 15 and faces the facing portion 18b of the second discharge electrode 18.

[0022] The second discharge electrode 18 has a lead portion 18a and a facing portion 18b. The lead portion 18a is an end portion of the second discharge electrode 18 facing outward in the X-axis direction. The lead portion 18a is exposed at the end surface 10a of the element body 10 and is electrically connected to the external electrode 8. On the other hand, the facing portion 18b is an end portion of the second discharge electrode 18 facing inward in the X-axis direction. The facing portion 18b is located inside the hollow portion 15 and faces the facing portion 16b of the first discharge electrode 16.

[0023] The facing portions 16b and 18b are spaced apart in the X-axis direction, and a gap G is formed between the facing portions 16b and 18b. When a voltage equal to or greater than a predetermined value is applied between the external electrode 6 and the external electrode 8, a discharge occurs in the gap G. The transient voltage protection component 2 serves to prevent the discharge between the facing portions 16b and 18b from causing a transient voltage to be applied to a device under protection (DUP). The width of the gap G in the X-axis direction is not particularly limited and may be determined appropriately so as to obtain desired discharge characteristics.

[0024] The discharge inducing section 13 is stacked below the discharge electrodes 16, 18 in the Z-axis direction so as to be in contact with both discharge electrodes 16, 18 in the stacking direction. In other words, the discharge inducing section 13 is formed across the first discharge electrode 16 and the second discharge electrode 18, connecting the opposing portion 16b and the opposing portion 18b. The discharge inducing section 13 has a substantially rectangular shape in a plan view when viewed in the stacking direction. The width of the discharge inducing section 13 in the X-axis direction is preferably greater than the width of the gap G, and the width of the discharge inducing section 13 in the Y-axis direction is preferably greater than the width of the opposing portion 16b and the width of the opposing portion 18b in the Y-axis direction. The average thickness of the discharge inducing section 13 is not particularly limited, but is preferably 1 μm to 15 μm, for example. The discharge inducing section 13 has the function of facilitating the generation of a discharge between the first discharge electrode 16 and the second discharge electrode 18.

[0025] The cavity 15 is a space formed by removing organic components (lacquer) during the manufacturing process of the transient voltage protection component 2. As shown in FIG. 2A , the surfaces defining the cavity 15 include the surface near the opposing portion 16 b of the first discharge electrode 16, the surface near the opposing portion 18 b of the second discharge electrode 18, the surface of the discharge inducing section 13, and the lower surface of the insulator layer 11 located above the discharge electrodes 16 and 18. The shape and dimensions of the cavity 15 are not particularly limited, but it is preferable that the cavity 15 be formed so as to cover the discharge inducing section 13 when viewed from the stacking direction. This cavity 15 functions to absorb thermal expansion of the first discharge electrode 16, the second discharge electrode 18, the insulator layer 11 near the discharge electrodes, and the discharge inducing section 13 during discharge.

[0026] Next, the materials of each component will be described.

[0027] The insulator layer 11 contains one or more inorganic compounds selected from Fe2O3, NiO, copper oxide (CuO, Cu2O), ZnO, MgO, SiO2, TiO2, MnCO3, SrCO3, CaCO3, BaCO3, Al2O3, ZrO2, and B2O3. It is particularly preferable that the insulator layer 11 contains ZrO2 and / or copper oxide. When two or more inorganic compounds are contained, the inorganic compounds may exist as a composite compound (e.g., CaZrO3). In addition to the inorganic compounds, the insulator layer 11 may also contain glass or a minor component compound containing a rare earth element or the like.

[0028] Both the first discharge electrode 16 and the second discharge electrode 18 contain a conductive material. Examples of conductive materials include Ag, Pd, Au, Pt, Cu, Ni, Al, Mo, W, and alloys containing at least one of these metal elements. The first discharge electrode 16 and the second discharge electrode 18 may contain different types of conductive materials, but it is preferable that the first discharge electrode 16 and the second discharge electrode 18 are made of the same type of conductive material. The first discharge electrode 16 and the second discharge electrode 18 may also contain trace amounts (for example, 1 wt % or less) of non-metallic components such as S and P, and may also contain the inorganic compound contained in the insulator layer 11 as a co-material.

[0029] As shown in FIG. 3, the discharge inducing unit 13 has a base material 31 and a plurality of metal particles 33 dispersed in the base material 31.

[0030] The metal particles 33 have a melting point (solidus temperature) higher than the firing temperature of the element body 10. Specifically, the metal particles 33 may be Ag particles, Pd particles, Au particles, Pt particles, Cu particles, Ag-Pd alloy particles, Ag-Au alloy particles, Ag-Pt alloy particles, etc., and it is preferable to use Pd particles or Ag-Pd alloy particles. The average particle size (D50) of the metal particles 33 in the cross section of the discharge triggered section 13 is preferably 2.0 μm or less. The content of the metal particles 33 is preferably 10 to 50 vol% with respect to 100 vol% of the discharge triggered section.

[0031] The average particle size and content of the metal particles 33 can be measured by observing the cross section of the discharge inducing part 13 as shown in FIG. 3 using a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM), and then performing image analysis on the obtained cross section photograph. For example, the average particle size of the metal particles 33 can be calculated by measuring the circle-equivalent diameters of at least 20 or more metal particles 33. The content of the metal particles 33 can be calculated based on the area ratio expressed as "total area of ​​the metal particles 33 included in the analytical field of view / area of ​​the analytical field of view." In this case, the analytical field of view is changed to obtain a particle size of at least 400 μm 2 It is preferable to measure the area of ​​the metal particles 33 within the above analytical field of view.

[0032] The substrate 31 contains glass 31a, and may also contain other materials such as semiconductor compounds such as SnO2 and RuO2, dielectric compounds, inorganic compounds that constitute the insulator layer 11, and other inorganic materials such as amorphous silica.

[0033] The glass 31a is interposed between the metal particles 33 and bonds the particles together. The presence of the glass 31a between the particles contributes to ensuring insulation between the metal particles 33 and ensuring the density of the discharge inducing section 13. The content of the glass 31a is preferably 10 wt% or more, and more preferably 12 wt% or more, relative to 100 wt% of the base material of the discharge inducing section 13. The upper limit of the content of the glass 31a is not particularly limited and can be 100 wt%, but is preferably 50 wt% or less.

[0034] Glass 31a contains at least SiO2, TiO2, and alkaline earth metal components as its main components. Here, alkaline earth metal elements are a general term for Be, Mg, Ca, Sr, Ba, and Ra, and in this embodiment, "alkaline earth metal components" refers to compounds containing alkaline earth metal elements. Glass 31a may contain one or more alkaline earth metal components. If alkaline earth metal elements are represented by the symbol M, the alkaline earth metal components contained in glass 31a are preferably oxides represented by the chemical formula MO. In particular, it is preferable that glass 31a contain one or more alkaline earth metal components selected from CaO, SrO, and BaO.

[0035] The content of TiO2 in the substrate 31 is preferably 0.05 wt% to 10 wt% and more preferably 0.10 wt% to 5 wt% based on 100 wt% of the substrate. The content of alkaline earth metal components in the substrate 31 is preferably 1 wt% to 50 wt% and more preferably 5 wt% to 45 wt% based on 100 wt% of the substrate.

[0036] Preferably, glass 31a has a higher SiO2 content than TiO2. Specifically, the mass ratio of Si to Ti (hereinafter referred to as the Si / Ti ratio) in substrate 31 is preferably 5 or more, and more preferably 10 or more. The upper limit of the Si / Ti ratio is not particularly limited, and can be, for example, 6000 or less, and is preferably 1200 or less.

[0037] In addition to the above-mentioned main components, the glass 31a may contain other components such as B2O3, Al2O3, etc. The content of the other components is not particularly limited, and for example, the content of B2O3 in the base material 31 can be 0.1 wt% to 20 wt% with respect to 100 wt% of the base material.

[0038] The glass 31a may also contain alkali metal components such as K2O and Na2O. However, alkali metal components may promote grain growth of the metal particles 33. Therefore, the content of alkali metal components in the base material 31 is preferably 2 wt% or less relative to 100 wt% of the base material, and more preferably, the base material is substantially free of alkali metal components. "Substantially free of alkali metal components" means that the content of alkali metal components is less than 0.1 wt%. Note that alkali metals are a general term for Li, Na, K, Rb, Cs, and Fr, and "alkali metal components" in this embodiment refers to compounds containing alkali metal elements. Typically, alkali metal components contained in glass are Li2O, Na2O, KO, etc.

[0039] The content of the above-mentioned base material components can be analyzed using various component analysis methods, such as energy dispersive X-ray analysis (EDX), electron probe microanalyzer (EPMA), electron beam diffraction in a TEM, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and X-ray fluorescence analysis (XRF).

[0040] As described above, the base material 31 may contain one or more non-glass materials, such as semiconductor compounds and dielectric compounds, in addition to the glass 31a. In this embodiment, it is particularly preferable that the base material 31 contains zirconia (ZrO2) particles 31b as the non-glass material. In this case, the content of the zirconia particles 31b can be 0 wt% to 90 wt%, and preferably 10 wt% to 80 wt%, relative to 100 wt% of the base material of the discharge triggered part 13. The average particle size (D50) of the zirconia particles 31b is not particularly limited, and is preferably 2 μm or less, for example.

[0041] The zirconia particles 31b in the substrate can be identified by, for example, mapping analysis using EDX or EPMA. The average particle size of the zirconia particles 31b can be calculated by measuring the equivalent circle diameter of the particles identified by the above method.

[0042] The first external electrode 6 and the second external electrode 8 can both include a baked electrode layer, a resin electrode layer, a plated electrode layer, etc., and may be composed of a single electrode layer or a laminate of multiple electrode layers. Generally, a baked electrode layer or a resin electrode layer is formed as a base electrode in contact with the element body 10, and a single or multiple plated electrode layer is formed on the surface of that base electrode.

[0043] When a baked electrode layer is formed, the baked electrode layer contains, as a conductive material, Ag, Cu, Pd, Au, Ni, or an alloy containing at least one of these metal elements. Glass frit or oxide particles may also be included. When a resin electrode layer is formed, the resin electrode layer contains the same conductive material as the baked electrode layer, as well as a thermosetting resin. When a plated electrode layer is formed, the type and number of layers of the plated electrode layer can be determined taking into account the mounting method and usage environment of the transient voltage protection component 2. For example, Ni plating / Sn plating, Cu plating / Ni plating / Sn plating, Ni plating / Pd plating / Au ​​plating, Ni plating / Pd plating / Ag plating, Ni plating / Ag plating, etc. can be used as the plated electrode layer.

[0044] Next, an example of a method for manufacturing the transient voltage protection component 2 will be described with reference to FIGS.

[0045] First, a slurry for the insulator layer containing the components of the insulator layer 11 is prepared. Specifically, the slurry for the insulator layer is obtained by adding raw material powders such as inorganic compounds and glass frit to an organic vehicle containing an organic solvent and an organic binder and kneading them. The slurry is then applied to a PET film by a doctor blade method or the like and dried appropriately to obtain multiple green sheets. In this embodiment, the sheet on which the discharge portion pattern is printed is referred to as the first green sheet 110, and the sheet on which the discharge portion pattern is not printed is referred to as the second green sheet 111.

[0046] Next, a discharge-induced portion pattern 130 as shown in Fig. 4 is formed on the first green sheet 110 using the discharge-induced portion slurry. The discharge-induced portion slurry is obtained by kneading glass frit, which is the raw material of the glass 31a, non-glass ceramic powder such as semiconductor powder or zirconia powder, metal powder, and an organic vehicle. The discharge-induced portion pattern 130 may be formed by various printing methods such as screen printing, a transfer method, or a coating method.

[0047] Next, a conductor pattern 168 as shown in FIG. 4 is formed on the first green sheet 110 using a discharge electrode paste. The discharge electrode paste is obtained by kneading conductive powder, which is the raw material for the discharge electrodes 16, 18, with an organic vehicle. The conductor pattern 168 is formed along the X-axis direction so as to straddle the surface of the first green sheet 110 and the surface of the discharge inducing section pattern 130. The conductor pattern 168 also has a slit S of a predetermined width on the surface of the discharge inducing section pattern 130. This slit S is an interruption where the conductor pattern 168 is not printed, and becomes a gap G after firing. The conductor pattern 168 can also be formed in the same manner as the discharge inducing section pattern 130.

[0048] Next, a cavity pattern 150 is formed using a cavity lacquer on the first green sheet on which the discharge inducing portion pattern 130 and the conductor pattern 168 have been printed. The cavity lacquer contains an organic solvent and an organic binder that disappear during firing, and the cavity pattern 150 is used to form an internal space in the opposing portion of the discharge electrodes. As shown in FIG. 4, the cavity pattern 150 is preferably formed so as to cover the discharge inducing portion pattern 130 and a portion of the conductor pattern 168 that will become the opposing portions 16b and 18b. Through the above process, a first green sheet 110 is obtained on which a discharge portion pattern including the discharge inducing portion pattern 130, the conductor pattern 168, and the cavity pattern 150 has been printed.

[0049] Next, the first green sheet 110 having the discharge portion pattern and a plurality of second green sheets 111 are stacked and pressed in the stacking direction to obtain the green chip 100. At this time, the first green sheets 110 are stacked between the second green sheets 111 as shown in FIG. 5. The number of stacked second green sheets 111 is not particularly limited, and the number of stacked second green sheets 111 above and below the first green sheet 110 may be different.

[0050] 4 and 5 illustrate the process of forming a single green chip for the sake of simplicity. However, in an actual manufacturing process, a green sheet having dimensions in the XY plane direction larger than that of the element body 10 is typically prepared, and multiple discharge portion patterns are printed continuously on the surface of the green sheet. A mother laminate is then formed using the green sheet, and multiple green chips are obtained by cutting this mother laminate at predetermined intervals.

[0051] Next, the green chip 100 obtained in the above step is subjected to a firing process to obtain the element body 10. The firing conditions are not particularly limited, and the conditions for sintering the element body 10 may be selected depending on the components contained in the element body 10. For example, the holding temperature may be 800°C to 950°C, the temperature holding time may be 0.1 to 3 hours, and the firing atmosphere may be air, an inert gas, or a reducing atmosphere. During this firing process, the cavity pattern 150 disappears, and a cavity 15 is formed where the cavity pattern 150 was stacked. Note that a binder removal process may be performed as appropriate before the firing process, and if firing is performed in a reducing atmosphere, a reoxidation process may be performed after firing.

[0052] Next, a pair of external electrodes 6, 8 are formed on the surface of the element body 10 obtained in the above process. The method for forming the external electrodes 6, 8 is not particularly limited. For example, when forming baked electrode layers as the external electrodes 6, 8, a conductive paste containing glass frit may be applied to the end surfaces of the element body 10, and then the element body 10 may be heat-treated under predetermined conditions (for example, in air at 600 to 800°C for 1 to 5 hours). When forming resin electrodes as the external electrodes 6, 8, a conductive paste containing a thermosetting resin may be applied to the end surfaces of the element body 10, and then the element body 10 may be heated at a temperature at which the thermosetting resin hardens. Furthermore, after forming baked electrodes or resin electrodes using the above method, the external electrodes 6, 8 may be formed with a multilayer structure by performing sputtering, vapor deposition, electrolytic plating, electroless plating, or the like.

[0053] Through the above manufacturing process, the transient voltage protection component 2 shown in FIG. 1 is obtained.

[0054] (Summary of the embodiment) In the transient voltage protection component 2 according to this embodiment, the base material 31 of the discharge inducing part 13 has glass 31a containing SiO2, TiO2, and an alkaline earth metal component.

[0055] Discharge triggering parts containing glass components have been known for some time, and glass components have been used to improve the density of the discharge triggering part. However, experiments by the inventors have revealed that in conventional discharge triggering parts, excessive grain growth of metal particles occurs during the process in which the glass component bonds between metal particles. Excessive grain growth of metal particles makes it easier for a pair of discharge electrodes to short-circuit through the discharge triggering part. In other words, when using conventional discharge triggering parts containing glass, it has been difficult to achieve both reduced short-circuit defects and high ESD resistance.

[0056] As a result of extensive investigation, the inventors have found that when the glass 31a of the discharge triggered part 13 contains an alkaline earth metal component and TiO2 in addition to SiO2, it is possible to improve the density of the discharge triggered part 13 while suppressing excessive grain growth of the metal particles 33. As a result, the transient voltage protection component 2 of this embodiment can suppress short-circuit defects and achieve high ESD resistance.

[0057] In particular, by controlling the composition of the main components of the glass 31a within a predetermined range, the dispersibility of the metal particles 33 and the density of the discharge inducing part 13 can be further improved, and the ESD resistance can be further increased. Specifically, the content of TiO2 in the base material 31 is 0.05 wt% or more and 10 wt% or less with respect to 100 wt% of the base material. Also, the Si / Ti ratio of the base material 31 is 5 or more. Since alkali metal components tend to promote grain growth of the metal particles 33, the content of the alkali metal component in the base material 31 is preferably 2 wt% or less, and more preferably is substantially free of alkali metal components.

[0058] The discharge triggered part 13 of this embodiment contains zirconia particles 31b in addition to glass 31a. The inclusion of the non-glass zirconia particles 31b in the base material 31 of the discharge triggered part 13 can more effectively suppress the grain growth of the metal particles 33 and further improve the ESD resistance. In addition, the zirconia particles 31b can improve the adhesion of the discharge triggered part 13 to the insulator layer 11.

[0059] (Variation) Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified in various ways within the scope of the present invention.

[0060] For example, the pair of discharge electrodes 16, 18 may face each other in the Y-axis direction. In the transient voltage protection component 2a shown in Fig. 6A, a side edge 16c of the first discharge electrode 16 along the Y-axis direction and a side edge 18c of the second discharge electrode 18 along the Y-axis direction face each other across a gap G. In other words, these side edges 16c, 18c are facing portions, and discharge occurs between the side edges 16c and 18c.

[0061] If the pair of discharge electrodes 16, 18, the discharge inducing part 13, and the cavity 15 are considered to be a discharge unit, then the element body 10 may include multiple discharge units. Furthermore, the transient voltage protection component does not have to have the cavity 15, and the discharge inducing part 13 may be filled between the pair of discharge electrodes.

[0062] 6B, element body 10 may include a coil 40. Furthermore, element body 10 may include a capacitor unit. The capacitor unit can be constructed by laminating internal electrode layers between insulator layers 11. [Example]

[0063] The present invention will be described in more detail below with reference to specific examples of the present invention, but the present invention is not limited to these examples. In Tables 1 to 3, samples marked with * are outside the scope of the present invention.

[0064] (Experiment 1) In Experiment 1, transient voltage protection components according to Samples 1 to 13 were manufactured using glass having a predetermined composition. The manufacturing conditions other than the glass composition were the same for Samples 1 to 13. The manufacturing method for transient voltage protection component 2 in Experiment 1 will be described below.

[0065] First, a slurry for the insulator layer, a slurry for the discharge triggered part, a paste for the discharge electrode, and a lacquer for the cavity were prepared. To the slurry for the insulator layer, glass and zirconia were added as raw material powders for the insulator layer, along with an organic vehicle. To the slurry for the discharge triggered part, an organic vehicle, glass frit having a predetermined composition, and Pd powder having an average particle size (D50) of 0.5 μm were added. In this slurry for the discharge triggered part, the compounding ratio of the glass frit and Pd powder was the same for all samples 1 to 13 in Experiment 1. To the paste for the discharge electrode, an organic vehicle and Pd powder, which is a conductive powder, were added.

[0066] Next, a green sheet was prepared using the above-mentioned slurry for the insulator layer, and then the slurry for the discharge inducing portion, the paste for the discharge electrode, and the lacquer for the cavity were applied to the green sheet in the order listed to form a pattern for the discharge portion.

[0067] Next, the green sheets printed with the discharge pattern and the green sheets without the discharge pattern were stacked in a predetermined order and pressed in the stacking direction to obtain a mother laminate, which was then cut to obtain multiple green chips for each sample.

[0068] Next, the green chip was fired in an air atmosphere at 800-950°C for 0.1-1 hour to obtain a sintered body. After that, a conductive paste containing Ag was applied to the outer surface of the body, and the body was heated at 700°C for 1 hour to form a fired electrode containing Ag. Through these processes, a transient voltage protection component having the structure shown in Figures 1-2B was obtained.

[0069] The dimensions of the element were 1 mm in width in the X-axis direction, 0.5 mm in width in the Y-axis direction, and 0.5 mm in height in the Z-axis direction, the average thickness of the discharge inducing part was 5 μm, the average thickness of the discharge electrodes was 5 μm, and the width of the gap G, which is the distance between the opposing discharge electrodes, was 50 μm.

[0070] In Experiment 1, the transient voltage protection component obtained by the above manufacturing process was evaluated as follows.

[0071] (Analysis of the discharge triggering part) The cross section of the transient voltage protection component was observed using an SEM to measure the average particle size (D50) and content of metal particles contained in the discharge triggering part. The average particle size was calculated by measuring the circle-equivalent diameter of 20 metal particles. The content of metal particles was in the range of 15 to 25 vol% in all samples. The composition of the base material contained in the discharge triggering part was also analyzed.

[0072] (Short circuit occurrence rate) The occurrence of short circuits between the discharge electrodes was investigated. Specifically, a voltage of 20 V, which is lower than the discharge start voltage, was applied to the manufactured transient voltage protection components. If a current flowed between the discharge electrodes at this time, it was determined that a short circuit had occurred in that sample. For each sample, this evaluation was performed on 100 transient voltage protection components, and the percentage of samples in which a short circuit had occurred (short circuit occurrence rate) was calculated. A short circuit occurrence rate of 3% or less was considered acceptable, and 0% was considered good.

[0073] (ESD tolerance) The ESD resistance of each sample was measured using the electrostatic discharge immunity test specified in IEC 61000-4-2. ESD resistance of 14 kV or more was considered pass, and 16 kV or more was considered good.

[0074] The evaluation results of each sample in Experiment 1 are shown in Table 1. [Table 1]

[0075] As shown in Table 1, samples 1 and 2 failed to meet the pass criteria for the short circuit occurrence rate and the ESD resistance rate. On the other hand, samples 3 to 13 were found to be more successful in suppressing the grain growth of metal particles than samples 1 and 2. As a result, samples 3 to 13 had a lower short circuit occurrence rate than samples 1 and 2, and also had better ESD resistance than samples 1 and 2. These results show that by including SiO2, TiO2, and alkaline earth metal components in the glass of the discharge triggering portion, it is possible to obtain high ESD resistance while suppressing the occurrence of short circuits.

[0076] Furthermore, in samples 4 to 8, the grain growth of metal particles was suppressed more than in sample 3, which had a lower TiO2 content, and the short circuit occurrence rate was particularly good. Also, samples 4 to 8 had higher ESD resistance than sample 9, which had a higher TiO2 content. From these results, it was found that the TiO2 content is preferably 0.05 wt% or more and 10 wt% or less relative to 100 wt% of the base material. It was also found that the Si / Ti ratio of the base material is preferably 5 or more.

[0077] Furthermore, the results of Samples 10 to 13 showed that the alkaline earth metal component contained in the glass may be of one type or of multiple types.

[0078] (Experiment 2) In Experiment 2, glass and zirconia were added to the discharge triggered section to manufacture transient voltage protection components according to Samples 21 to 24. The experimental conditions in Experiment 2 were the same as those in Experiment 1, except for the composition of the base material in the discharge triggered section, and Samples 21 to 24 in Experiment 2 were also evaluated in the same manner as in Experiment 1. The evaluation results of Experiment 2 are shown in Table 2.

[0079] [Table 2]

[0080] The results shown in Table 2 indicate that adding zirconia to the discharge triggered part in addition to the specified glass components can further suppress the grain growth of metal particles. It was also found that the ZrO2 content is preferably 90 wt% or less, and that the glass content in the base material of the discharge triggered part is preferably 10 wt% or more.

[0081] (Experiment 3) In Experiment 3, transient voltage protection components according to Samples 31 and 32 were manufactured using glass containing specified components in addition to SiO2, TiO2, and alkaline earth metal components. Specifically, the glass of Sample 31 contained B2O3, and the glass of Sample 32 contained Na2O as an alkali metal component. The experimental conditions in Experiment 3 were the same as those in Experiment 1, except for the glass composition, and Samples 31 and 32 of Experiment 3 were evaluated in the same manner as in Experiment 1. The evaluation results of Experiment 3 are shown in Table 3.

[0082] [Table 3]

[0083] The results for Sample 31 shown in Table 3 show that even when glass containing a predetermined main component and B2O3 is used, it is possible to suppress the occurrence of short circuits and obtain high ESD resistance.

[0084] The results of Sample 2 in Experiment 1 showed that alkali metal components may promote the grain growth of metal particles. However, the results of Sample 32 shown in Table 3 showed that if the content of alkali metal components is 2 wt% or less relative to 100 wt% of the base material, the grain growth of metal particles can be suppressed. [Explanation of symbols]

[0085] 2, 2a, 2b ... Transient voltage protection components 10... Base body 10a … End face 10b…side 10c…Main surface 11...insulator layer 13...Discharge triggering section 31 … Base material 31a ... Glass 31b... Zirconia particles 33 … Metal particles 15 … Cavity part 16 … 1st discharge electrode 16a...Drawer part 16b...Opposing part 18…Second discharge electrode 18a...Drawer part 18a … Opposing part 6 … 1st external electrode 8 … Second external electrode 100...Green Chip 110 ... 1st Green Sheet 130 ... Pattern for discharge induction part 150 ... Hollow pattern 168...conductor pattern 111 ... 2nd Green Sheet

Claims

1. a pair of discharge electrodes facing each other across a gap; a discharge inducing unit adjacent to the pair of discharge electrodes, the discharge inducing unit has a base material containing glass and a plurality of metal particles dispersed in the base material, The glass is SiO 2 , TiO 2 and an alkaline earth metal component, The Si / Ti ratio in the substrate is 5 or more, a content of the alkaline earth metal in the base material is 5 wt % or more and 45 wt % or less with respect to 100 wt % of the base material; The content of TiO 2 in the substrate is 0.05 wt % or more and 10 wt % or less with respect to 100 wt % of the substrate. Transient voltage protection components.

2. The glass is B 2 O 3 The transient voltage protection component of claim 1 , comprising:

3. The transient voltage protection component of claim 1 or 2, wherein the substrate comprises zirconia.

4. TiO in the substrate 2 4. The transient voltage protection component according to claim 1, wherein the content of said component (I) is 0.1 wt % or more and 5 wt % or less with respect to 100 wt % of said base material.

5. 5. The transient voltage protection component according to claim 1, wherein the content of the alkali metal component in the substrate is 2 wt % or less relative to 100 wt % of the substrate.

6. 4. The transient voltage protection component according to claim 3, wherein the content of the zirconia is 10 to 80 wt % relative to 100 wt % of the base material.

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