JP5867136B2 - ESD protection parts - Google Patents

Description

  The present invention relates to an electrostatic protection component that protects an electronic device from ESD (Electro-Static Discharge).

  There is known an electrostatic protection component including an element body in which a plurality of ceramic layers are laminated and a pair of discharge electrodes arranged in the same layer apart from each other in the element body (see, for example, Patent Document 1). In the electrostatic protection component described in Patent Document 1, a discharge inducing portion that induces a discharge between the discharge electrodes is formed.

Japanese Patent No. 4,247,581

  By the way, in the electrostatic protection component described in Patent Document 1, the discharge inducing portion is disposed below the facing portion of the discharge electrode. In general, the discharge inducing portion is destroyed at the location where the discharge is caused by the discharge. Therefore, in the electrostatic protection component described in Patent Document 1, breakdown due to discharge in the discharge inducing portion proceeds mainly in the stacking direction of the ceramic layers, that is, in the thickness direction of the discharge inducing portion. As described above, when the discharge inducing portion is destroyed in the thickness direction, it is difficult to cause discharge along the discharge inducing portion.

  For this reason, the electrostatic protection component described in Patent Document 1 has a limited number of discharges, and the discharge start voltage changes (discharge start voltage increases), so the durability of the electrostatic protection component is reduced. Had problems. It is possible to increase the durability of the electrostatic protection component by increasing the thickness of the discharge inducing portion. In this case, however, the thickness of the discharge inducing portion is increased, resulting in an increase in the height of the electrostatic protection component, which causes new problems such as preventing the static protection component from being lowered and increasing the cost. I will.

  In addition, when the breakdown allowable area of the discharge inducing portion is small, there is a problem that the peak voltage and the clamp voltage are likely to increase when the discharge is repeatedly performed.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide an electrostatic protection component capable of improving durability and reducing a clamp voltage.

  The electrostatic protection component according to the present invention includes a first and second discharges arranged in the same layer of the element body so as to face each other through a predetermined gap in the element body with a plurality of ceramic layers laminated. The electrode includes a discharge inducing portion that contacts the first and second discharge electrodes and connects the first and second discharge electrodes to each other in the element body. In this electrostatic protection component, the element body has a hollow portion adjacent to and in contact with the discharge inducing portion in the gap, and the hollow portion overlaps the discharge inducing portion.

  In the electrostatic protection component according to the present invention, the cavity portion is adjacent to and in contact with the discharge inducing portion in the gap. In this case, the breakdown due to the discharge can be induced in the horizontal direction, and the breakdown of the discharge inducing portion due to the discharge in the thickness direction (the stacking direction of the ceramic layers) can be suppressed. Since the destruction in the thickness direction of the discharge inducing portion is suppressed in this way, according to the electrostatic protection component according to the present invention, it is also suppressed that the number of discharges is limited or the discharge start voltage is changed. Thereby, it becomes possible to improve the durability of the electrostatic protection component.

  Moreover, in the electrostatic protection component according to the present invention, the cavity portion is formed so as to overlap the discharge inducing portion. In this case, it is possible to increase the space region (thickness in the stacking direction) in the vicinity of the discharge location where discharge is likely to occur in the discharge inducing portion. Since the space region in the vicinity of the discharge location can be increased, the electrostatic protection component according to the present invention can reduce the clamp voltage.

  In the electrostatic protection component, the first discharge electrode extends in the first direction and has a first side edge extending along the first direction, and the second discharge electrode extends in the first direction. And a second side edge extending along the first direction, and the first and second discharge electrodes have a second side edge intersecting the first direction. You may arrange | position so that it may mutually oppose in a direction. In this case, it is possible to increase the length of breakage in the horizontal direction due to discharge, and to further improve the durability of the electrostatic protection component.

  In the static electricity protection component, the discharge inducing portion may be formed of first and second discharge inducing portions, and the cavity may overlap both the first and second discharge inducing portions. In this case, since the cavity is formed on the inner side, it is possible to suppress the intrusion of the plating solution and moisture from the outside. Thereby, durability and reliability of an electrostatic protection component can be improved.

  In the electrostatic protection component, the cavity may cover the entire first and second discharge inducing portions. In this case, since the gap portion can be formed large, it is possible to further suppress breakage due to discharge.

  In the static electricity protection component, the hollow portion may cover both edges in the first direction of the discharge inducing portion in the gap. In this case, since it is not necessary to provide a hollow portion that does not overlap the discharge inducing portion at the center of the gap, the hollow portion can be made compact. Further, according to this configuration, since the opposing length of the discharge electrodes can be shortened, it is possible to reduce the capacitance generated between the discharge electrodes.

  ADVANTAGE OF THE INVENTION According to this invention, the electrostatic protection component which improved durability and reduced the clamp voltage can be provided.

It is a perspective view of the electrostatic protection component which concerns on 1st Embodiment of this invention. It is an expansion | deployment perspective view of the element | base_body of the electrostatic protection component which concerns on 1st Embodiment of this invention. It is the top view which looked at the discharge part of the electrostatic protection component shown in FIG. 1 from the lamination direction. (A) is a cross-sectional view showing a cross-sectional configuration along line IVa-IVa shown in FIG. 3, and (b) is a cross-sectional view showing a cross-sectional configuration along line IVb-IVb shown in FIG. is there. It is a longitudinal cross-sectional view which shows the cross-sectional structure along the VV line of the electrostatic protection component shown in FIG. It is a schematic cross section for demonstrating the material structure of the discharge induction part of the electrostatic protection component shown in FIG. It is a flowchart which shows an example of the manufacturing method of the electrostatic protection component shown in FIG. It is a top view for demonstrating the printing formation of the discharge part of the electrostatic protection component shown in FIG. (A) is the top view which looked at the discharge part of the electrostatic protection component used as a comparative example from the lamination direction, (b) is a cross-sectional view schematically showing the cross-sectional configuration of the electrostatic protection component shown in (a) (C) is a cross-sectional view schematically showing a cross-sectional configuration of a discharge portion of the electrostatic protection component shown in FIG. 1. It is the figure which compared the clamp voltage of the electrostatic protection component (structure 1) of a comparative example, and the electrostatic protection component (configuration 2) shown in FIG. It is an expansion | deployment perspective view of the element | base_body in the modification of the electrostatic protection component which concerns on 1st Embodiment. It is the top view which looked at the discharge part of the electrostatic protection component which concerns on 2nd Embodiment of this invention from the lamination direction. It is a cross-sectional view which shows typically the cross-sectional structure of the discharge part of the electrostatic protection component shown in FIG. It is a top view for demonstrating the printing formation of the discharge part of the electrostatic protection component shown in FIG. It is the top view which looked at the discharge part of the electrostatic protection component which concerns on another modification from the lamination direction.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

[First Embodiment]
FIG. 1 is a perspective view of the electrostatic protection component according to the first embodiment. FIG. 2 is an exploded perspective view of the element body of the electrostatic protection component according to the first embodiment. FIG. 3 is a plan view of the discharge portion of the electrostatic protection component as viewed from the stacking direction. In FIG. 3, the ceramic layer 2 and the like on the first and second discharge electrodes 4A and 4B are omitted. 4A is a view for explaining a cross-sectional configuration along the line IVa-IVa shown in FIG. 3, and FIG. 4B is a cross section along the line IVb-IVb shown in FIG. It is a figure for demonstrating a structure. FIG. 5 is a diagram for explaining a cross-sectional configuration along the line VV shown in FIG. In the following description, the direction in which the element body 3 extends is the longitudinal direction D1, the direction perpendicular to the longitudinal direction D1 in the planar direction of the ceramic layer 2 is the short direction D2, and the direction in which the ceramic layer 2 is laminated is the lamination direction D3. And

  First, the structure of the electrostatic protection component 1 according to the present embodiment will be described with reference to FIGS. The electrostatic protection component 1 is an electronic component that is mounted on a circuit board of an electronic device and protects the electronic device from ESD. The electrostatic protection component 1 includes an element body 3 having a substantially rectangular parallelepiped shape in which a plurality of ceramic layers 2 are stacked, and first and second discharges disposed on the same ceramic layer 2 while being spaced apart from each other in the element body 3. The electrodes 4A and 4B, the first and second external electrodes 6A and 6B disposed on the opposite end surfaces 3a and 3b of the element body 3, and the first and second discharge electrodes 4A and 4B are connected to each other. The first and second discharge inducing portions 8A and 8B are provided.

  The first discharge electrode 4A is electrically connected to the first external electrode 6A, and the second discharge electrode 4B is electrically connected to the second external electrode 6B. The element body 3 has a cavity portion 7 formed so as to overlap the first and second discharge inducing portions 8A and 8B (see FIG. 5). The cavity portion 7 has a function of absorbing thermal expansion of the ceramic layer 2 and the discharge inducing portion 8. The arrangement relationship between the cavity portion 7 and the discharge inducing portions 8A and 8B will be described later. In the actual electrostatic protection component 1, the element body 3 is integrated so as not to be visually recognized.

  As shown in FIGS. 2 and 3, the first and second discharge electrodes 4 </ b> A and 4 </ b> B are arranged on the same ceramic layer 2 so as to be separated from each other in the element body 3. 4 A of 1st discharge electrodes have the main-body part 11A extended along the longitudinal direction D1 (1st direction) toward the end surface 3b side of the other side from the end surface 3a of the element | base_body 3. As shown in FIG. The main body 11A has a distal end 12A and a base end 13A in the longitudinal direction D1, and side edges 14A and side edges 15A extending along the longitudinal direction D1. The main body 11A has a long rectangular shape, with the distal end 12A and the base end 13A constituting a short side, and the side edges 14A and 15A constituting a long side. That is, the side edges 14A and 15A are longer than the distal end 12A and the proximal end 13A.

  11 A of main-body parts are arrange | positioned slightly on the side surface 3c side of the element | base_body 3 rather than the center position in the transversal direction D2. The base end 13A is exposed from the end face 3a of the element body 3 and is connected to the first external electrode 6A. The distal end 12A extends to a position separated from the end surface 3b, and is disposed at a position closer to the end surface 3b than the center position in the longitudinal direction D1. The side edge 14A is an edge portion on the side surface 3d side of the element body 3, and is disposed slightly on the side surface 3c side with respect to the center position in the lateral direction D2. The side edge 15A is an edge portion on the side surface 3c side of the element body 3, and is disposed at a position separated from the side surface 3c. The length of the main body 11A may be longer or shorter than that shown in FIG.

  The second discharge electrode 4B has a point-symmetric relationship with the first discharge electrode 4A around the center of the element body 3 when viewed from the stacking direction D3. That is, the second discharge electrode 4B has a main body portion 11B extending along the longitudinal direction D1 from the end surface 3b of the element body 3 toward the opposite end surface 3a side. The main body 11B has a distal end 12B and a base end 13B in the longitudinal direction D1, and a side edge 14B and a side edge 15B extending along the longitudinal direction D1. The main body 11B has a long rectangular shape, and the distal end 12B and the base end 13B form a short side, and the side edges 14B and 15B form a long side. That is, the side edges 14B and 15B are longer than the distal end 12B and the proximal end 13B.

  The main body portion 11B is disposed slightly on the side surface 3d side of the element body 3 with respect to the center position in the short direction D2. The base end 13B is exposed from the end surface 3b of the element body 3 and is connected to the second external electrode 6B. The distal end 12B extends to a position separated from the end surface 3a, and is disposed at a position closer to the end surface 3a than the center position in the longitudinal direction D1. The side edge 14B is an edge on the side surface 3c side of the element body 3, and is disposed slightly on the side surface 3d side with respect to the center position in the lateral direction D2. The side edge 15B is an edge portion on the side surface 3d side of the element body 3, and is disposed at a position spaced from the side surface 3d. Note that the length of the main body 11B may be longer or shorter than that shown in FIG.

  As shown in FIG. 3, the first and second discharge electrodes 4A and 4B are arranged on the side edge 14A of the facing region 16A on the tip 12A side of the first discharge electrode 4A and the tip 12B side of the second discharge electrode 4B. It arrange | positions so that the side edge 14B of the opposing area | region 16B may oppose. The side edge 14A of the facing region 16A of the first discharge electrode 4A and the side edge 14B of the facing region 16B of the second discharge electrode 4B are spaced apart from each other, thereby facing the first discharge electrode 4A and the second discharge electrode 4A. A gap GP (see FIG. 4 and the like) is formed between the discharge electrode 4B. The gap width (the distance between the side edge 14A and the side edge 14B) of the gap part GP is, for example, 10 to 100 μm. The gap part GP is formed only in the facing region where the side edge 14A and the side edge 14B are opposed to each other (see FIG. 3).

  Further, in the present embodiment, the first discharge electrode 4A is constituted only by the main body portion 11A having a long rectangular shape, and has a portion facing the tip 12B of the second discharge electrode 4B in the longitudinal direction D1. Not. The second discharge electrode 4B is configured only by a main body portion 11B having a long rectangular shape, and does not have a portion facing the tip 12A of the first discharge electrode 4A in the longitudinal direction D1. With such a configuration, when a predetermined voltage or higher is applied to the first and second external electrodes 6A and 6B, the side edge 14A is formed between the first and second discharge electrodes 4A and 4B in the gap portion GP. , 14B only.

  As shown in FIGS. 3 and 4, the first and second discharge inducing portions 8A and 8B connect the first and second discharge electrodes 4A and 4B to each other to connect the first and second discharge electrodes 4A. , 4B has a function of easily generating a discharge. The first and second discharge inducing portions have a substantially rectangular shape when viewed from the stacking direction D3.

  The first discharge inducing portion 8A is formed so as to be in contact with the portion on the base end 13A side in the opposed region 16A of the first discharge electrode 4A and the portion on the distal end 12B side in the opposed region 16B of the second discharge electrode 4B. Has been. Specifically, as shown in FIG. 4B, the first discharge inducing portion 8A is disposed so as to be in contact with the surfaces of both the discharge electrodes 4A and 4B, and connects both the discharge electrodes 4A and 4B. A portion having a substantially semi-elliptical shape when viewed from the longitudinal direction D1 and a portion disposed in the gap GP, which is a region facing both the discharge electrodes 4A and 4B, are provided.

  The second discharge inducing portion 8B is formed so as to be in contact with the portion on the tip 12A side in the facing region 16A of the first discharge electrode 4A and the portion on the base end 13B side in the facing region 16B of the second discharge electrode 4B. Has been. Specifically, the second discharge inducing portion 8B is arranged so as to be in contact with the surfaces of both the discharge electrodes 4A and 4B and connects both the discharge electrodes 4A and 4B in the longitudinal direction, similarly to the first discharge inducing portion 8A. A portion having a substantially semi-elliptical shape when viewed from the direction D1 and a portion disposed in the gap GP which is a region facing both the discharge electrodes 4A and 4B are included.

  Further, as shown in FIGS. 3 and 5, the element body 3 is disposed between the first and second discharge inducing portions 8A and 8B so as to be adjacent to and in contact with the discharge inducing portions 8A and 8B in the gap GP. The cavity portion 7 is formed. That is, the cavity 7 is disposed at the approximate center in the longitudinal direction D1 of the gap GP. At the approximate center of the gap GP, as shown in FIG. 4A, the first and second discharge electrodes 4A. , 4B is provided with a gap. As shown in FIG. 5, the cavity portion 7 has a substantially dome shape when viewed from the short side direction D <b> 2, and both edges in the longitudinal direction D <b> 1 have a substantially semi-elliptical shape. It is formed so as to overlap the induction parts 8A and 8B. With such an arrangement configuration of the discharge inducing portions 8A and 8B and the cavity portion 7, the discharge is induced along the boundary portions 18A and 18B between the cavity portion 7 and the discharge inducing portions 8A and 8B.

  Next, the material of each component will be described in detail.

  The discharge electrodes 4A and 4B are made of a conductive material containing at least one of Ag, Pd, Au, Pt, Cu, Ni, Al, Mo, and W. For example, for the discharge electrodes 4A and 4B, an Ag / Pd alloy, an Ag / Cu alloy, an Ag / Au alloy, an Ag / Pt alloy, or the like can be used as an alloy. The external electrodes 6A and 6B are made of a conductive material containing Ag, Pd, Au, Pt, Cu, Ni, Al, Mo, and W. For example, for the external electrodes 6A and 6B, an Ag / Pd alloy, an Ag / Cu alloy, an Ag / Au alloy, an Ag / Pt alloy, or the like can be used as an alloy.

The ceramic layer 2 is made of Fe ₂ O ₃ , NiO, CuO, ZnO, MgO, SiO ₂ , TiO ₂ , MnCO ₃ , SrCO ₃ , CaCO ₃ , BaCO ₃ , Al ₂ O ₃ , ZrO ₂ , B ₂ O _3, etc. It is comprised by the material which mixed the single material in them, or two or more types. Glass may be contained. The ceramic layer 2 preferably contains copper oxide (CuO, Cu ₂ O) in order to enable low-temperature sintering.

The discharge inducing portions 8A and 8B are Fe ₂ O ₃ , NiO, CuO, ZnO, MgO, SiO ₂ , TiO ₂ , MnCO ₃ , SrCO ₃ , CaCO ₃ , BaCO ₃ , Al ₂ O ₃ , ZrO ₂ , B ₂ O _It is comprised by the single material in ₃ etc., or the material which mixed 2 or more types. The discharge inducing portions 8A and 8B contain metal particles such as Ag, Pd, Au, Pt, Ag / Pd alloy, Ag / Cu alloy, Ag / Au alloy, Ag / Pt alloy, or semiconductor particles such as RuO _2. It is preferable that Moreover, glass may be contained. The discharge inducing portions 8A and 8B preferably contain tin oxide (SnO, SnO ₂ ).

  FIG. 6 is a schematic diagram for explaining the material configuration of the discharge inducing portion 8A. With reference to FIG. 6, the structure in the case of using a preferable material will be described. FIG. 6 is a schematic configuration diagram for explanation, and the size and number of each particle are shown in a deformed state. The same applies to the discharge inducing portion 8B.

In the discharge inducing portion 8A, tin oxide (SnO ₂ ) particles 22 and an Ag / Pd alloy are contained in a ceramic insulator 21 containing, as a main component, an oxide of Mg, Cu, Zn, Si, Sr, or the like. The metal particles 23 are present in a mixed state. The mixed state is a state in which the Ag / Pd alloy metal particles 23 are not hardened at one place but the tin oxide particles 22 enter between the metal particles 23. The tin oxide particles 22 are present in an unsintered particle state (however, some particles are in the form of agglomerated powder). Tin oxide functions as a semiconductor material and can be discharged even when the gap size of the gap portion GP is larger than when the metal particles 23 exist alone by being disposed between the metal particles 23. The alloy ratio of the Ag / Pd alloy of the metal particles 23 is 95/5 to 30/70. The content of the tin oxide particles 22 is preferably 5/95 to 80/20 wt% in a tin oxide / ceramic insulator ratio. The content of the metal particles 23 is preferably 10 to 35 vol% with respect to the discharge inducing portion 8A.

  The ceramic layer 2 contains Mg, Cu, Zn, Si, Sr oxide, and the like as main components, and contains copper oxide (CuO) particles 24 in a ceramic containing glass. The content of the copper oxide particles 24 is preferably 0.01 to 5 wt%.

  The first and second discharge electrodes 4A and 4B are made of a conductive material whose main component is an Ag / Pd alloy. The alloy ratio of the Ag / Pd alloy of the first and second discharge electrodes 4A and 4B is 95/5 to 30/70. The alloy ratio of the Ag / Pd alloy of the first and second discharge electrodes 4A and 4B and the Ag / Pd alloy of the metal particles 23 is preferably the same.

  Tin oxide is characterized by a very high sintering temperature (specifically, about 1300 ° C.) and low reactivity with other elements. Accordingly, the tin oxide remains in the form of particles at the temperature during firing of the element body 3 and does not react with the metal particles 23 even if the metal particles 23 exist around. In the discharge inducing portion 8A, the following effects are achieved by making the tin oxide particles 22 and the metal particles 23 coexist. That is, at the time of firing the element body 3, the tin oxide particles 22 remain in the form of particles without reacting with the surrounding metal particles 23. Thus, the tin oxide particles 22 remain without reacting, so that the metal particles 23 are restricted from moving in the discharge inducing portion 8A. Since the metal particles 23 whose movement is restricted do not react with each other, it is possible to prevent a short circuit between the discharge electrodes 4A and 4B (or a decrease in insulation resistance) due to the connection between the metal particles 23. .

  Further, since the discharge inducing portion 8A contains an insulator such as the ceramic insulator 21, insulation between the first and second discharge electrodes 4A and 4B can be ensured.

  Moreover, in the electrostatic protection component 1, while the ceramic layer 2 contains the highly reactive copper oxide particles 24, the discharge inducing portion 8 contains the tin oxide particles 22 having a high sintering temperature and low reactivity. By adopting the configuration, the following effects are achieved. That is, even if the ceramic layer 2 contains the copper oxide particles 24, the diffusion of the copper oxide particles 24 into the discharge inducing portion 8 is suppressed by the tin oxide particles 22. As described above, since the diffusion of the copper oxide particles 24 is suppressed, in the discharge inducing portion 8A, constituent materials in portions other than tin oxide can be freely selected (that is, the discharge inducing portion 8A is oxidized). It is composed of tin and other materials, but other materials can be selected freely). As described above, the element body 3 can contain copper oxide while ensuring the degree of freedom in selecting the constituent material of the discharge inducing portion 8A.

  Moreover, the discharge start voltage can be lowered by including the metal particles 23 in the discharge inducing portion 8A.

  The Ag / Pd alloy has a high melting point (specifically, about 1000 ° C.) and a low reactivity with copper oxide. While the ceramic layer 2 contains highly reactive copper oxide particles 24, the discharge inducing part 8 contains a Ag / Pd alloy having low reactivity with copper oxide as the metal particles 23. Thus, the following effects are produced. That is, even if the ceramic layer 2 contains the copper oxide particles 24, the reaction between the metal particles 23 due to the influence of the diffusion of the copper oxide particles 24 is suppressed in the discharge inducing portion 8A. That is, it is possible to prevent the discharge electrodes 4A and 4B from being short-circuited (or the insulation resistance is lowered) by connecting the metal particles 23 to each other. As described above, the element body 3 can contain copper oxide while preventing a short circuit between the first and second discharge electrodes 4A and 4B. Although Pd alone has a high melting point, its reactivity with copper oxide is higher than that of an Ag / Pd alloy. Therefore, the effect becomes more remarkable by using an alloyed material with Ag.

  Moreover, in the structure in which the element body 3 contains copper oxide, if a metal other than Ag / Pd is used for the first and second discharge electrodes 4A and 4B, it reacts with the copper oxide, and the following Problems can arise. For example, Ag / Pd may vaporize and disappear from the exposed portions of the first and second discharge electrodes 4A and 4B from the element body 3 (connections to the external electrodes 6A and 6B, etc.). In addition, if the facing portions (near side edges 14A and 14B) of the first and second discharge electrodes 4A and 4B disappear, the gap length may vary and the characteristics may not be stable. Therefore, the occurrence of such a problem can be prevented by the first and second discharge electrodes 4A and 4B containing the Ag / Pd alloy. A metal other than Ag / Pd may be used for the first and second discharge electrodes 4A and 4B.

  Further, when an Ag / Pd alloy is contained in the discharge inducing portion 8A and an Ag / Pd alloy is contained in the discharge electrodes 4A and 4B, the discharge ratio is induced by making the alloy ratio of each Ag / Pd alloy the same. It is possible to prevent the Ag / Pd alloy from reacting between the portion 8A and the first and second discharge electrodes 4A and 4B.

  Next, an example of a method for manufacturing the electrostatic protection component 1 will be described with reference to FIGS. However, a manufacturing method is not specifically limited, The order of each process may be changed, the specific method in a process may be changed, and you may manufacture by another process.

  First, the slurry of the material which comprises the ceramic layer 2 is adjusted, and the sheet | seat for ceramic layers is created (S10). Specifically, a predetermined amount of dielectric powder containing copper oxide (CuO) and an organic vehicle containing an organic solvent and an organic binder are mixed to prepare a slurry for the ceramic layer. As the dielectric powder, a dielectric material containing, as a main component, an oxide of Mg, Cu, Zn, Si, or Sr (may be another dielectric material) can be used. Then, a slurry is apply | coated on PET film by the doctor blade method etc., and a green sheet about 20 micrometers thick is formed.

  Next, a discharge portion is formed by printing at a predetermined position of the ceramic layer sheet. First, as shown in FIG. 8A, a conductive pattern of the discharge electrodes 4A and 4B before firing is formed by applying a conductive paste to the ceramic layer 2 sheet by screen printing or the like (S20). In addition, in the discharge electrodes 4A and 4B shown in FIG. 8, the modified example in which the base end 13A and 13B side portions approach the substantially central portion in the short direction D2 is disclosed, but the discharge electrodes 4A and 4B shown in FIG. It has almost the same function.

Subsequently, the discharge inducing material slurry is prepared, and as shown in FIG. 8B, the discharge electrodes 4A and 4B are connected so that the opposing regions 16A and 16B of the discharge electrodes 4A and 4B are connected at two locations. Then, the slurry is applied to form portions corresponding to the discharge inducing portions 8A and 8B before firing (S30). Specifically, tin oxide, insulator, and conductor powders weighed to a predetermined amount and an organic vehicle containing an organic solvent and an organic binder are mixed to prepare a discharge inducing material slurry. For example, SnO ₂ which is an industrial raw material can be used as tin oxide. Dielectric powder can be used as the insulator. As the dielectric powder, a dielectric material containing, as a main component, an oxide of Mg, Cu, Zn, Si, or Sr (may be another dielectric material) can be used. As the conductor powder, Ag / Pd powder can be used (Ag, Pd, Au, Pt, and mixtures and compounds thereof may be used). Each powder is sufficiently mixed so that tin oxide particles and Ag / Pd alloy metal particles are mixed.

  Subsequently, as shown in FIG. 8C, a gap material lacquer for forming the cavity portion 7 is applied on the discharge inducing portions 8A and 8B so that both ends thereof overlap. As the gap material lacquer, an organic lacquer containing an organic solvent and an organic binder can be used. As a result, a portion that becomes the cavity 7 after firing is formed (S40).

  Subsequently, the ceramic layer sheet on which the discharge portion is printed and the ceramic layer sheet of other layers are sequentially laminated (S50), pressed (S60), and laminated so as to have the size of each electrostatic protection component. The body is cut (S70). Next, each element body is fired at predetermined conditions (for example, in the atmosphere at 850 to 950 ° C. for 2 hours) (S80). At this time, the void material lacquer disappears inside the element body 3, thereby forming a cavity 7 in the discharge portion. Thereafter, a conductive paste for external electrodes is applied to the element body 3, and heat treatment is performed under predetermined conditions (for example, at 600 to 800 ° C. for 2 hours in the atmosphere), and the external electrodes are baked (S90). Thereafter, the surface of the external electrode is plated. The plating is preferably electrolytic plating. For example, Ni / Sn, Cu / Ni / Sn, Ni / Pd / Au, Ni / Pd / Ag, Ni / Ag, or the like can be used. Thus, the electrostatic protection component 1 is completed.

  As described above, in the electrostatic protection component 1, the cavity portion 7 is adjacent to and in contact with the discharge inducing portions 8A and 8B in the gap GP. For this reason, the breakdown by discharge can be induced in the longitudinal direction D1 (horizontal direction), and the breakdown of the discharge inducing portions 8A and 8B by the discharge in the thickness direction (lamination direction D3 of the ceramic layer 2) can be suppressed. . As described above, since the breakdown in the thickness direction of the discharge inducing portions 8A and 8B is suppressed, according to the electrostatic protection component 1, the number of discharges is limited and the discharge start voltage is also suppressed. Thereby, durability of the electrostatic protection component 1 can be enhanced.

  Moreover, in the electrostatic protection component 1, the cavity part 7 overlaps on the discharge induction parts 8A and 8B (refer FIG. 5). In this case, as shown in FIG. 9C, the space region (thickness in the stacking direction) in the vicinity of the discharge points 18A and 18B where discharge is likely to occur in the discharge inducing portions 8A and 8B can be increased. For example, as shown in FIGS. 9A and 9B, a lacquer for the cavity 27 is first applied on the discharge electrodes 4A and 4B, and a discharge inducing portion 28 is formed so as to cover the lacquer. As a result, the thickness of the discharge locations 28A and 28B where discharge is likely to occur becomes thin and the clamp voltage becomes about 81 V, for example (see “Structure 1” in FIG. 10). However, the electrostatic protection component 1 according to the present embodiment. As described above, since the space area in the vicinity of the discharge points 18A and 18B can be increased, the clamp voltage of the electrostatic protection component 1 can be reduced to, for example, about 35 V (see “Structure 2” in FIG. 10). "reference).

  In the electrostatic protection component 1, the first discharge electrode 4A extends in the longitudinal direction D1 and has a first side edge 14A extending along the longitudinal direction D1, and the second discharge electrode 4B extends in the longitudinal direction D1. The first and second discharge electrodes 4A and 4B have a first side edge 14A and a second side edge 14B in the short direction D2. Are arranged so as to face each other. For this reason, it is possible to increase the length of the horizontal breakage caused by the discharge, and to further improve the durability of the electrostatic protection component 1.

  In the electrostatic protection component 1, the cavity portion 7 is disposed substantially at the center of the gap GP so as to overlap both the first and second discharge inducing portions 8A and 8B. Thus, since the cavity part 7 will be formed more inside, the penetration | invasion of the plating solution and water | moisture from the outside can be suppressed. Thereby, durability and reliability of the electrostatic protection component 1 can be improved.

  In the above-described embodiment, the lacquer forming the cavity portion 7 is formed so as to cover a part of the discharge inducing portions 8A and 8B. However, as shown in FIG. The electrostatic protection component 1 may be formed by applying lacquer so as to cover the entire 8A and 8B. In this case, since the gap portion can be formed large, it is possible to further suppress breakage due to discharge.

[Second Embodiment]
Next, with reference to FIG.12 and FIG.13, the electrostatic protection component 1 which concerns on 2nd Embodiment is demonstrated. As in the first embodiment, the electrostatic protection component 1 according to the present embodiment includes the element body 3, the discharge electrodes 4A and 4B, and the external electrodes 6A and 6B. The second embodiment is different from the first embodiment in that a hollow portion 37 is formed so as to overlap the discharge inducing portion 38.

  The discharge inducing portion 38 has a substantially rectangular shape when viewed from the stacking direction D3, and connects the first and second discharge electrodes 4A and 4B to each other to connect the first and second discharge electrodes 4A and 4B. It has a function to easily generate electric discharge. The discharge inducing portion 38 is formed so as to be in contact with a substantially central portion of the opposing region 16A of the first discharge electrode 4A and a substantially central portion of the opposing region 16B of the second discharge electrode 4B. Specifically, the discharge inducing portion 38 is disposed so as to be in contact with the surfaces of both the discharge electrodes 4A and 4B, connects both the discharge electrodes 4A and 4B, and has a substantially semi-elliptical shape when viewed from the longitudinal direction D1, And a portion disposed in the gap GP, which is a region facing both the discharge electrodes 4A and 4B.

  As shown in FIG. 12 and FIG. 13, a hollow portion 37 of the element body 3 is formed at a substantially central portion in the short direction D2 of the discharge inducing portion 38 so as to be adjacent to the discharge inducing portion 38 in the gap GP. Is formed. That is, the cavity part 37 is arrange | positioned in the approximate center in the longitudinal direction D1 of the gap GP. Further, as shown in FIG. 13, the cavity 7 has a substantially dome shape when viewed from the short direction D <b> 2 and is formed so as to overlap the entire discharge inducing portion 38. With such an arrangement configuration of the discharge inducing portion 38 and the cavity portion 37, the discharge is induced along the boundary portions 38 </ b> A and 38 </ b> B between the cavity portion 37 and the discharge inducing portion 38.

  The discharge part of the electrostatic protection component 1 having such a configuration is formed by printing as in the first embodiment. First, as shown in FIG. 14A, a conductive pattern of the discharge electrodes 4A and 4B before firing is formed by applying a conductive paste to the sheet for the ceramic layer 2 by screen printing or the like (FIG. 7). S20). Next, as shown in FIG. 14 (b), slurry is applied from above the discharge electrodes 4A and 4B so that the substantially central portions of the opposed regions 16A and 16B of the discharge electrodes 4A and 4B are connected at one place. It applies and forms the discharge induction part 38 before baking (S30 of FIG. 7). Thereafter, as shown in FIG. 14 (c), a gap material lacquer for forming the cavity portion 37 is applied so as to overlap the entire substantially central portion of the discharge inducing portion 38 in the short direction D2. To do. Thus, a portion that becomes the cavity 37 after firing is formed (S40 in FIG. 7).

  As described above, also in the electrostatic protection component 1 according to the second embodiment, the cavity portion 37 is adjacent to and in contact with the discharge inducing portion 38 in the gap GP. For this reason, the breakdown by discharge can be induced | guided | derived to the longitudinal direction D1 (horizontal direction), and the breakdown to the thickness direction (lamination direction D3 of the ceramic layer 2) of the discharge induction part 38 by discharge can be suppressed. Thus, since the breakdown in the thickness direction of the discharge inducing portion 38 is suppressed, according to the electrostatic protection component 1, it is also possible to suppress the number of discharges from being limited and the discharge start voltage from being changed. The durability of the electrostatic protection component 1 can be increased.

  Further, in the electrostatic protection component 1, the cavity portion 37 is overlapped on the substantially central portion in the short direction D <b> 2 of the discharge inducing portion 38 so as to cover both edges in the longitudinal direction D <b> 1 of the discharge inducing portion 38 ( (See FIG. 12). In this case, as shown in FIG. 13, it is possible to increase the space area (thickness in the stacking direction) in the vicinity of the discharge locations 38 </ b> A and 38 </ b> B where discharge is likely to occur in the discharge inducing portion 38. For this reason, according to the electrostatic protection component 1 according to the present embodiment, the clamp voltage of the electrostatic protection component 1 can be reduced.

  Moreover, in the electrostatic protection component 1, the cavity part 37 is arrange | positioned so that the both edges in the longitudinal direction D1 of the discharge induction part 38 may be covered in the gap GP. For this reason, since it is not necessary to provide the cavity part which does not overlap with the discharge induction part 38 in the center part of the gap GP, the cavity part 37 can be made compact. In addition, according to this configuration, since the opposing length of the discharge electrodes 4A and 4B can be shortened, the capacitance generated between the discharge electrodes 4A and 4B can be reduced.

  The preferred embodiment of the present invention has been described in detail above. However, the above-described embodiment is an embodiment of the electrostatic protection component according to the present invention, and the electrostatic protection component according to the present invention is described in this embodiment. It is not limited to what has been described. The electrostatic protection component according to the present invention may be obtained by modifying the electrostatic protection component according to the embodiment or applying it to other components without changing the gist described in each claim.

  For example, the configuration of the first and second discharge electrodes 4A and 4B is not limited to the configuration shown in FIG. 3 and the like, and the length, width, and gap size may be changed as appropriate. Further, for example, the configuration shown in FIG. 15 may be adopted.

  In the configuration shown in FIG. 15, the first discharge electrode 4A extends from the end surface 3a of the element body 3 in the longitudinal direction D1, and the second discharge electrode 4B extends from the end surface 3b of the element body 3 in the longitudinal direction D1. The tip 12A of the electrode 4A and the tip 12B of the discharge electrode 4B face each other to form a gap part GP. Further, the first and second discharge electrodes 4A and 4B are connected to each other at a substantially central portion in the short direction D2 by a discharge inducing portion 48, and a cavity portion 47 is formed so as to cover the discharge inducing portion 48. Has been. In addition, the arrangement | positioning relationship between the discharge induction part 48 and the cavity part 47 in the structure shown in FIG. 15 is substantially the same as that of 2nd Embodiment.

  In the above-described embodiment, the electrostatic protection component including only the discharge portion having the electrostatic protection function is exemplified. However, the present invention is applied to the electrostatic protection component integrated by adding other functions such as a coil portion and a capacitor portion. May be. At this time, the material of the ceramic layer 2 may be changed to an optimum material for each layer with respect to each of the discharge portion, the coil portion, and the capacitor portion.

  DESCRIPTION OF SYMBOLS 1 ... Electrostatic protection component, 2 ... Ceramic layer, 3 ... Element body, 4A ... 1st discharge electrode, 4B ... 2nd discharge electrode, 7, 37, 47 ... Cavity part, 8A ... 1st discharge induction part, 8B ... 2nd discharge induction part, 14A, 14B, 15A, 15B ... Side edge, 38, 48 ... Discharge induction part.

Claims (5)

An element body in which a plurality of ceramic layers are laminated;
First and second discharge electrodes arranged in the same layer of the element body so as to face each other with a predetermined gap in the element body;
A discharge inducing portion for contacting the first and second discharge electrodes and connecting the first and second discharge electrodes to each other in the element;
The body, the has a cavity in contact adjacent horizontally against the discharge inducing portion in the gap, the electrostatic protection, characterized in that the cavities overlap also on the discharge inducing section parts. The first discharge electrode extends in a first direction and has a first side edge extending along the first direction;
The second discharge electrodes extend in the first direction, a second side edge extending along said first direction,
The said 1st and 2nd discharge electrode is arrange | positioned so that the said 1st and 2nd side edge may mutually oppose in the 2nd direction which cross | intersects the said 1st direction. The electrostatic protection component according to 1.   The discharge inducing part is formed of first and second discharge inducing parts, and the cavity overlaps both the first and second discharge inducing parts. 2. The electrostatic protection component according to 2.   The electrostatic protection component according to claim 3, wherein the hollow portion covers the entire first and second discharge inducing portions.   The electrostatic protection component according to claim 2, wherein the hollow portion covers both edges of the discharge inducing portion in the first direction in the gap.

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