# Patent

## Title
ESD protection component

## Abstract

An ESD protection component includes opposite electrodes and a ground electrode. The opposite electrodes and the ground electrode each have an extraction portion and an opposite portion. The respective opposite portions of the opposite electrodes and the ground electrode are placed on the same layer. At least one of the opposite electrodes and the ground electrode, the extraction portion and the opposite portion are placed on respective different layers and, also, are electrically connected to each other via a through hole conductor.

## Background
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to ESD protection component.
Related Background Art
There have been known ESD protection component including an element body constituted by a plurality of insulator layers are stacked, opposite electrodes and a ground electrode which are placed to be spaced apart from each other inside the element body, and a plurality of external electrodes which are each provided correspondingly to a respective one of the opposite electrodes and the ground electrode (eg., cf. Japanese Patent Application Laid-Open Publication No. 2013-114788 (which will be referred to hereinafter as Patent Literature 1)). In the ESD protection component described in Patent Literature 1, the opposite electrodes and the ground electrode are exposed in the exterior surface of the element body in the same layer and are connected to the respective external electrodes placed on the exterior surface of the element body.
SUMMARY OF THE INVENTION
In the ESD protection component described in the aforementioned Patent Literature 1, the plurality of the electrodes are placed on the same layer and, also, these plural electrodes are exposed in the exterior surface of the element body in the same layer, which makes the total area of the electrodes in the same layer larger. This degrades the adherence between the insulator layers, thereby increasing the possibility of occurrences of structural defects.
The external electrodes are formed by applying a conductive paste and performing heat treatment thereon and, thereafter, performing electroplating thereon. Therefore, the ESD protection component is necessarily subjected to the plating solution during the manufacturing process. Accordingly, it is likely that structural defects are induced in the ESD protection component, which tends to induce infiltration of the plating solution into the element body, through the portions of the respective electrodes placed on the insulator layer which are exposed in the exterior surface of the element body. As a result thereof, the plating solution infiltrates therein up to the discharging portions for inducing discharge within the element body, and the gap portions may be filled with this plating solution, thereby inducing short-circuits.
It is an object of the present invention to provide a ESD protection component which can inhibit infiltration of a plating solution into discharging portions therein.
A ESD protection component in one aspect of the present invention includes: an element body constituted by a plurality of insulator layers are stacked; a ground electrode placed inside the element body; a first opposite electrode which is placed to be spaced apart from the ground electrode and forms a discharging portion in cooperation with the ground electrode; a second opposite electrode which is placed to be spaced apart from the ground electrode and forms a discharging portion in cooperation with the ground electrode; and a plurality of external electrodes each being provided correspondingly to a respective one of the ground electrode, the first opposite electrode and the second opposite electrode; wherein the ground electrode, the first opposite electrode and the second opposite electrode are each adapted to have an extraction portion connected to the corresponding external electrode out of the plurality of the external electrodes, and an opposite portion which is electrically connected to the extraction portion and forms the discharging portion, the opposite portion of the ground electrode, the opposite portion of the first opposite electrode, and the opposite portion of the second opposite electrode are placed on the same layer, and, in at least one of the ground electrode, the first opposite electrode and the second opposite electrode, the extraction portion and the opposite portion are placed on respective different layers and also are electrically connected to each other via a through hole conductor.
With the ESD protection component in the one aspect of the present invention, in at least one of the ground electrode, the first opposite electrode and the second opposite electrode, the extraction portion and the opposite portion are placed on the respective different layers and also are electrically connected to each other through the through hole conductor. This makes the total area of the electrodes existing in the same layer smaller. This can enhance the adherence between the insulator layers, which can reduce the possibility of occurrences of structural defects, thereby suppressing infiltration of the plating solution through such defects. This can suppress the infiltration of the plating solution into the discharging portion formed by the ground electrode and the first opposite electrode, and the discharging portion formed by the ground electrode and the second opposite electrode.
With the ESD protection component in one aspect of the present invention, the extraction portion of the ground electrode and the opposite portion of the ground electrode may be placed on respective different layers and also may be electrically connected to each other via a through hole conductor. In this case, the extraction portion of the ground electrode is placed on a different layer from the layer on which the respective opposite portions of the ground electrode, the first opposite electrode and the second opposite electrode are placed. This enables freely determining the conductor patterns of the respective opposite portions, regardless of the pattern of the extraction portion of the ground electrode, in the layer on which the respective opposite portions are placed.
In the ESD protection component in one aspect of the present invention, the extraction portion of the first opposite electrode and the opposite portion of the first opposite electrode may be placed on respective different layers and also may be electrically connected to each other via a through hole conductor, and the extraction portion of the second opposite electrode and the opposite portion of the second opposite electrode may be placed on respective different layers and also may be electrically connected to each other via a through hole conductor. In this case, the total area of the electrodes existing in the same layer is further reduced. This can further enhance the adherence between the insulator layers, which can further reduce the possibility of occurrences of structural defects, thereby further suppressing infiltration of the plating solution through such defects. This can suppress the infiltration of the plating solution into the discharging portions, more certainly.
In a ESD protection component in one aspect of the present invention, each of the extraction portions may have an end connected to the corresponding external electrode out of the plurality of the external electrodes, the end being exposed from the element body, the exterior surface has a first region in which the end of the extraction portion of the first opposite electrode is exposed and a second region in which the end of the extraction portion of the second opposite electrode is exposed, and the opposite portion of the ground electrode may be placed at a position closer to the first region than the opposite portion of the first opposite electrode and, also, the opposite portion of the ground electrode may be placed at a position closer to the second region than the opposite portion of the second opposite electrode. In this case, the opposite portion of the first opposite electrode and the opposite portion of the second opposite electrode are placed to be spaced apart from the exterior surfaces of the element body more largely than the opposite portion of the ground electrode, which can increase both the length of the extension of the extraction portion of the first opposite electrode from the exterior surface of the element body to the opposite portion, and the length of the extension of the extraction portion of the second opposite electrode from the exterior surface of the element body to the opposite portion. This increases the distances from the portions of the first opposite electrode and the second opposite electrode which are exposed in the exterior surfaces of the element body to their opposite portions, which inhibits the plating solution having entered through these exposed portions from infiltrating into the opposite portions. This can suppress the infiltration of the plating solution into the discharging portions formed by the opposite portions.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view illustrating ESD protection component according to first to fifth embodiments;
FIG. 2 is an exploded perspective view illustrating the structure of an element body according to the first embodiment;
FIG. 3 is an exploded perspective view illustrating the structure of a portion including first to fourth discharging portions in FIG. 2;
FIG. 4 is a view illustrating the structure of a cross section including the first discharging portion and the third discharging portion in the ESD protection component according to the first embodiment;
FIG. 5 is a view illustrating the structure of a cross section including the second discharging portion and the fourth discharging portion in the ESD protection component according to the first embodiment;
FIG. 6 is a flow chart illustrating a method for manufacturing the ESD protection component according to the first embodiment;
FIG. 7 is an exploded perspective view illustrating the structure of a portion including first to fourth discharging portions in an element body according to the second embodiment;
FIG. 8 is a view illustrating the structure of a cross section including the first discharging portion and the third discharging portion in the ESD protection component according to the second embodiment;
FIG. 9 is a view illustrating the structure of a cross section including the second discharging portion and the fourth discharging portion in the ESD protection component according to the second embodiment;
FIG. 10 is an exploded perspective view illustrating the structure of a portion including first to fourth discharging portions in an element body according to the third embodiment;
FIG. 11 is a view illustrating the structure of a cross section including the first discharging portion and the third discharging portion in the ESD protection component according to the third embodiment;
FIG. 12 is a view illustrating the structure of a cross section including the second discharging portion and the fourth discharging portion in the ESD protection component according to the third embodiment;
FIG. 13 is an exploded perspective view illustrating the structure of a portion including first to fourth discharging portions in an element body according to the fourth embodiment;
FIG. 14 is a view illustrating the structure of a cross section including the first discharging portion and the third discharging portion in the ESD protection component according to the fourth embodiment;
FIG. 15 is a view illustrating the structure of a cross section including the second discharging portion and the fourth discharging portion in the ESD protection component according to the fourth embodiment;
FIG. 16 is an exploded perspective view illustrating the structure of an element body according to a fifth embodiment;
FIG. 17 is a view illustrating the structure of a cross section including a first discharging portion and a third discharging portion in the ESD protection component according to the fifth embodiment; and
FIG. 18 is a view illustrating the structure of a cross section including a second discharging portion and a fourth discharging portion in the ESD protection component according to the fifth embodiment.



DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, an embodiment of the present invention will be described in detail, with reference to the accompanying drawings. Further, in the description, the same components or components having the same functions will be designated by the same reference characters and will not be described redundantly.
First Embodiment
At first, with reference to FIGS. 1 to 5, the structure of a ESD protection component according to a first embodiment will be described. FIG. 1 is a perspective view illustrating the ESD protection component according to first to fifth embodiments. FIG. 2 is an exploded perspective view illustrating the structure of an element body according to the first embodiment. FIG. 3 is an exploded perspective view illustrating the structure of a portion including first to fourth discharging portions in FIG. 2. FIG. 4 is a view illustrating the structure of a cross section including the first discharging portion and the third discharging portion in the ESD protection component according to the first embodiment. FIG. 5 is a view illustrating the structure of a cross section including the second discharging portion and the fourth discharging portion in the ESD protection component according to the first embodiment.
An ESD protection component 1A according to the present embodiment is an electronic member which is mounted on a circuit board in an electronic apparatus and is adapted to protect the electronic apparatus from ESD (Electro-Static Discharge). As illustrated in FIGS. 1 to 5, the ESD protection component 1A includes an element body 4, external electrodes 5 to 10, opposite electrodes 12, 14, 16 and 18, two or more discharging portions (a first discharging portion GP1, a second discharging portion GP2, a third discharging portion GP3 and a fourth discharging portion GP4), discharge inducing portions 24 and 25, cavity portions 26 to 29, and coils L1 and L2. The element body 4 has a substantially-rectangular parallelepiped shape. The external electrodes 5 to 10 are placed on the exterior surface of the element body 4. The opposite electrodes 12, 14, 16 and 18 are placed inside the element body 4. A ground electrode 20 is placed inside the element body 4. The first discharging portion GP1, the second discharging portion GP2, the third discharging portion GP3 and the fourth discharging portion GP4 are placed inside the element body 4. The discharge inducing portions 24 and 25 are placed inside the element body 4. The cavity portions 26 to 29 are placed inside the element body 4. The coils L1 and L2 are placed inside the element body 4. Hereinafter, a stack direction of the plurality of insulator layers in the element body 4 will be defined as a Z direction (an upward/downward direction), the widthwise direction in the end surfaces and cross sections in the stack direction (hereinafter, simply referred to as “the widthwise direction of the element body 4”) will be defined as an X direction, and the longitudinal direction thereof (hereinafter, simply referred to as “the longitudinal direction of the element body 4”) will be defined as a Y direction.
The element body 4 is constituted by a plurality of insulator layers 11 which are stacked. Each insulator layer 11 has a substantially-rectangular shape. Each insulator layer 11 is an insulator having an electrically-insulating property and is formed from a sintered insulator green sheet. In the actual element body 4, the respective insulator layers 11 are integrated with each other so that no boundary can be visually recognized between them. The element body 4 has a pair of end surfaces 4a and 4b opposed to each other, and four side surfaces adjacent to the end surfaces 4a and 4b, as exterior surfaces. A side surface 4c, out of the four side surfaces, is defined as a surface (a mounting surface) which is faced to another electronic apparatuses (for example, a circuit board or an electronic member) which is not illustrated.
The external electrode 5 is placed on the side surface 4e of the element body 4. The external electrode 5 is placed at a position closer to the end surface 4a than to the end surface 4b, in the longitudinal direction (the Y direction in the figure) of the element body 4. The external electrode 5 is formed such that it partially covers a portion of the side surface 4c of the element body 4 and a portion of the side surface 4d of the element body 4.
The external electrode 6 is placed on the side surface 4f of the element body 4. The external electrode 6 is placed at a position closer to the end surface 4a than to the end surface 4b, in the longitudinal direction of the element body 4. The external electrode 6 is formed such that it partially covers a portion of the side surface 4c of the element body 4 and a portion of the side surface 4d of the element body 4.
The external electrode 7 is placed on the side surface 4e of the element body 4. The external electrode 7 is placed at a position closer to the end surface 4b than to the end surface 4a, in the longitudinal direction of the element body 4. The external electrode 7 is formed such that it partially covers a portion of the side surface 4c of the element body 4 and a portion of the side surface 4d of the element body 4.
The external electrode 8 is placed on the side surface 4f of the element body 4. The external electrode 8 is placed at a position closer to the end surface 4b than to the end surface 4a, in the longitudinal direction of the element body 4. The external electrode 8 is formed such that it partially covers a portion of the side surface 4c of the element body 4 and a portion of the side surface 4d of the element body 4.
The external electrode 9 is placed on the end surface 4a of the element body 4. The external electrode 9 is placed at a substantially-center position, in the widthwise direction (the X direction in the figure) of the element body 4. The external electrode 9 is formed such that it partially covers a portion of the side surface 4c of the element body 4 and a portion of the side surface 4d of the element body 4.
The external electrode 10 is placed on the end surface 4b of the element body 4. The external electrode 10 is placed at a substantially-center position, in the widthwise direction of the element body 4. The external electrode 10 is formed such that it partially covers a portion of the side surface 4c of the element body 4 and a portion of the side surface 4d of the element body 4.
The opposite electrode 12 is placed at a position closer to the end surface 4a than to the end surface 4b in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4e than to the side surface 4f in the widthwise direction of the element body 4. The opposite electrode 12 has a first extraction portion 12a and a first opposite portion 12b (see FIG. 3). The first extraction portion 12a and the first opposite portion 12b are placed on respective different insulator layers 11. The first extraction portion 12a has an I shape extending in the widthwise direction of the element body 4. The first extraction portion 12a has an end portion 12c which is exposed in the side surface 4e of the element body 4 and is connected to the external electrode 5. The first opposite portion 12b has an I shape extending in the longitudinal direction of the element body 4. The first opposite portion 12b is electrically connected to the first extraction portion 12a, via a through hole conductor 13 positioned between the first opposite portion 12b and the first extraction portion 12a. 
The opposite electrode 14 is placed at a position closer to the end surface 4b than to the end surface 4a in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4e than to the side surface 4f in the widthwise direction of the element body 4. The opposite electrode 14 has a first extraction portion 14a and a first opposite portion 14b. The first extraction portion 14a is placed on a different insulator layer 11 from the layer on which the first opposite portion 12b of the opposite electrode 12 is placed, and the first opposite portion 14b is placed on the same insulator layer 11 as the layer on which the first opposite portion 12b of the opposite electrode 12 is placed. Namely, the first extraction portion 14a and the first opposite portion 14b are placed on the respective different insulator layers 11. The first extraction portion 14a has an I shape extending in the width direction of the element body 4. The first extraction portion 14a has an end portion 14c which is exposed in the side surface 4e of the element body 4 and is connected to the external electrode 7. The first opposite portion 14b has an I shape extending in the longitudinal direction of the element body 4. The first opposite portion 14b is electrically connected to the first extraction portion 14a, via a through hole conductor 15 positioned between the first opposite portion 14b and the first extraction portion 14a. 
The opposite electrode 16 is placed at a position closer to the end surface 4a than to the end surface 4b in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4f than to the side surface 4e in the widthwise direction of the element body 4. The opposite electrode 16 has a first extraction portion 16a and a first opposite portion 16b. The first extraction portion 16a is placed on a different insulator layer 11 from the layer on which the first opposite portion 12b of the opposite electrode 12 is placed, and the first opposite portion 16b is placed on the same insulator layer 11 as the layer on which the first opposite portion 12b of the opposite electrode 12 is placed. Namely, the first extraction portion 16a and the first opposite portion 16b are placed on the respective different insulator layers 11. The first extraction portion 16a has an I shape extending in the width direction of the element body 4. The first extraction portion 16a has an end portion 16c which is exposed in the side surface 4f of the element body 4 and is connected to the external electrode 6. The first opposite portion 16b has an I shape extending in the longitudinal direction of the element body 4. The first opposite portion 16b is electrically connected to the first extraction portion 16a, via a through hole conductor 17 positioned between the first opposite portion 16b and the first extraction portion 16a. 
The opposite electrode 18 is placed at a position closer to the end surface 4b than to the end surface 4a in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4f than to the side surface 4e in the widthwise direction of the element body 4. The opposite electrode 18 has a first extraction portion 18a and a first opposite portion 18b. The first extraction portion 18a is placed on a different insulator layer 11 from the layer on which the first opposite portion 12b of the opposite electrode 12 is placed, and the first opposite portion 18b is placed on the same insulator layer 11 as the layer on which the first opposite portion 12b of the opposite electrode 12 is placed. Namely, the first extraction portion 18a and the first opposite portion 18b are placed on the respective different insulator layers 11. The first extraction portion 18a has an I shape extending in the width direction of the element body 4. The first extraction portion 18a has an end portion 18c which is exposed in the side surface 4f of the element body 4 and is connected to the external electrode 8. The first opposite portion 18b has an I shape extending in the longitudinal direction of the element body 4. The first opposite portion 18b is electrically connected to the first extraction portion 18a, via a through hole conductor 19 positioned between the first opposite portion 18b and the first extraction portion 18a. 
The ground electrode 20 is placed at a substantially-center position in the widthwise direction of the element body 4. The ground electrode 20 includes a second extraction portion 20a, a second extraction portion 20b, a second opposite portion 20c and a second opposite portion 20d. The second extraction portion 20a and the second extraction portion 20b are placed on a different insulator layer 11 from the layer on which the first opposite portion 12b of the opposite electrode 12 is placed, and the second opposite portion 20c and the second opposite portion 20d are placed on the same insulator layer 11 as the layer on which the first opposite portion 12b of the opposite electrode 12 is placed. Namely, the second extraction portion 20a and the second extraction portion 20b, and the second opposite portion 20c and the second opposite portion 20d are placed on the respective different insulator layers 11.
The second extraction portion 20a is placed at a position closer to the end surface 4a than to the end surface 4b in the longitudinal direction of the element body 4 and, also, at a substantially-center position in the widthwise direction of the element body 4. The second extraction portion 20a has an I shape extending in the longitudinal direction of the element body 4. The second extraction portion 20a has an end portion 20g which is exposed in the end surface 4a of the element body 4 and is connected to the external electrode 9.
The second extraction portion 20b is placed at a position closer to the end surface 4b than to the end surface 4a in the longitudinal direction of the element body 4 and, also, at a substantially-center position in the widthwise direction of the element body 4. The second extraction portion 20b has an I shape extending in the longitudinal direction of the element body 4. The second extraction portion 20b has an end portion 20h which is exposed in the end surface 4b of the element body 4 and is connected to the external electrode 10.
The second opposite portion 20c and the second opposite portion 20d are extended in the longitudinal direction of the element body 4. An end of the second opposite portion 20c and an end of the second opposite portion 20d are connected to each other to form a connection portion 20e. The connection portion 20e is electrically connected to the second extraction portion 20a via a through hole conductor 21. Thus, the second opposite portion 20c and the second opposite portion 20d are electrically connected to the second extraction portion 20a via the through hole conductor 21. The other end of the second opposite portion 20c and the other end of the second opposite portion 20d are connected to each other to form a connection portion 20f. The connection portion 20f is electrically connected to the second extraction portion 20b via a through hole conductor 22. Thus, the second opposite portion 20c and the second opposite portion 20d are electrically connected to the second extraction portion 20b via the through hole conductor 22. The second opposite portion 20c, the second opposite portion 20d, the connection portion 20e, and the connection portion 20f form a loop-shaped conductor pattern on the same insulator layer 11. The second opposite portion 20c and the second opposite portion 20d are extended in the longitudinal direction of the element body 4, in such a way as to be separated from each other with the connection portion 20e and the connection portion 20f serving as branch points.
The second opposite portion 20c is placed to face the first opposite portion 12b of the opposite electrode 12 and the first opposite portion 14b of the opposite electrode 14, in such a way as to be spaced apart therefrom. Thus, the first discharging portion GP1 is formed between the first opposite portion 12b of the opposite electrode 12 and the second opposite portion 20c of the ground electrode 20 (see FIG. 4), and the second discharging portion GP2 is formed between the first opposite portion 14b of the opposite electrode 14 and the second opposite portion 20c of the ground electrode 20 (see FIG. 5). With this structure, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 5 and the external electrode 9, discharging is induced in the first discharging portion GP1. Similarly, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 7 and the external electrode 10, discharging is induced in the second discharging portion GP2.
The second opposite portion 20d is placed to face the first opposite portion 16b of the opposite electrode 16 and the first opposite portion 18b of the opposite electrode 18, in such a way as to be spaced apart therefrom. Thus, the third discharging portion GP3 is formed between the first opposite portion 16b of the opposite electrode 16 and the second opposite portion 20d of the ground electrode 20 (see FIG. 4), and the fourth discharging portion GP4 is formed between the first opposite portion 18b of the opposite electrode 18 and the second opposite portion 20d of the ground electrode 20 (see FIG. 5). With this structure, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 6 and the external electrode 9, discharging is induced in the third discharging portion GP3. Similarly, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 8 and the external electrode 10, discharging is induced in the fourth discharging portion GP4.
The discharge inducing portion 24 is positioned for the first discharging portion GP1 and the third discharging portion GP3 and has the function of facilitating the occurrence of discharge in the first discharging portion GP1 and the third discharging portion GP3. The discharge inducing portion 24 connects the first opposite portion 12b of the opposite electrode 12 to the second opposite portion 20c of the ground electrode 20 and, also, connects the first opposite portion 16b of the opposite electrode 16 to the second opposite portion 20d of the ground electrode 20.
The discharge inducing portion 25 is positioned for the second discharging portion GP2 and the fourth discharging portion GP4 and has the function of facilitating the occurrence of discharge in the second discharging portion GP2 and the fourth discharging portion GP4. The discharge inducing portion 25 connects the first opposite portion 14b of the opposite electrode 14 to the second opposite portion 20c of the ground electrode 20 and, also, connects the first opposite portion 18b of the opposite electrode 18 to the second opposite portion 20d of the ground electrode 20.
The cavity portion 26 is formed for the first discharging portion GP1. The cavity portion 26 has the function of absorbing thermal expansions of the first opposite portion 12b, the second opposite portion 20c, the insulator layer 11 and the discharge inducing portion 24 during discharging. The cavity portion 27 is formed for the second discharging portion GP2. The cavity portion 27 has the function of absorbing thermal expansions of the first opposite portion 14b, the second opposite portion 20c, the insulator layer 11 and the discharge inducing portion 25 during discharging. The cavity portion 28 is formed for the third discharging portion GP3. The cavity portion 28 has the function of absorbing thermal expansions of the first opposite portion 16b, the second opposite portion 20d, the insulator layer 11 and the discharge inducing portion 24, during discharging. The cavity portion 29 is formed for the fourth discharging portion GP4. The cavity portion 29 has the function of absorbing thermal expansions of the first opposite portion 18b, the second opposite portion 20d, the insulator layer 11 and the discharge inducing portion 25, during discharging.
The coil L1 and the coil L2 are placed closer to the side surface 4c of the element body 4, than the layers on which the opposite electrodes 12, 14, 16 and 18 and the ground electrode 20 are placed, in the stack direction of the plurality of insulator layers 11. The coil L1 and the coil L2 are placed, such that the coil L2 and the coil L1 are juxtaposed in the mentioned order from the side closer to the side surface 4c of the element body 4. The coil L2 is constituted by conductors 51 and 52 which are plural internal conductors juxtaposed in the stack direction of the plurality of insulator layers 11 inside the element body 4, and a through hole conductor 56 which is positioned between the conductors 51 and 52 and connects end portions of the conductors 51 and 52 to each other. The conductor 52 has a spiral shape. The conductors 51 and 52 are placed, such that the conductor 51 and the conductor 52 are juxtaposed in the mentioned order from the side closer to the side surface 4c of the element body 4, in the stack direction of the plurality of insulator layers 11.
The conductor 51 has an end portion 51a which is exposed in the side surface 4e of the element body 4 and is connected to the external electrode 5. The conductor 52 has an end portion 52a which is exposed in the side surface 4f of the element body 4 and is connected to the external electrode 6. Accordingly, the coil L2 is electrically connected to the external electrode 5 and the external electrode 6.
The coil L1 is constituted by conductors 53 and 54 which are plural internal conductors juxtaposed in the stack direction of the plurality of insulator layers 11 inside the element body 4, and a through hole conductor 55 which is positioned between the conductors 53 and 54 and connects end portions of the conductors 53 and 54 to each other. The conductor 54 has a spiral shape. The conductors 53 and 54 are placed, such that the conductor 53 and the conductor 54 are juxtaposed in the mentioned from the side closer to the side surface 4d of the element body 4, in the stack direction of the plurality of insulator layers 11.
The conductor 53 has an end portion 53a which is exposed in the side surface 4e of the element body 4 and is connected to the external electrode 7. The conductor 54 has an end portion 54a which is exposed in the side surface 4f of the element body 4 and is connected to the external electrode 8. Accordingly, the coil L1 is electrically connected to the external electrode 7 and the external electrode 8.
The coil L1 and the coil L2 form a so-called common-mode filter, since the conductors 52 and 54 which have the respective spiral shapes are magnetically coupled to each other.
Next, the materials of the respective constituents will be described in detail.
The external electrodes 5 to 10, the opposite electrodes 12, 14, 16 and 18, and the ground electrode 20 are formed from respective conductor materials containing Ag, Pd, Au, Pt, Cu, Ni, Al, Mo or W. The external electrodes 5 to 10 can be formed from an alloy such as an Ag/Pd alloy, an Ag/Cu alloy, an Ag/Au alloy or an Ag/Pt alloy.
The insulator layers 11 are formed from a material, out of Fe2O3, NiO, CuO, ZnO, MgO, SiO2, TiO2, Mn2O3, SrO, CaO, BaO, SnO2, K2O, Al2O3, ZrO2, B2O3 and the like. The insulator layers 11 may be also formed from a ceramic material made of a mixture of two or more types of materials, out of them. The insulator layers 11 may contain a glass. The insulator layers 11 preferably contain copper oxide (CuO or Cu2O), in order that they can be sintered at lower temperatures.
Each of the conductors 51 to 54 and each of the through hole conductors 13, 15, 17, 19, 21, 22, 55 and 56 contain a conductor material such as Ag or Pd, for example. The respective conductors 51 to 54 and the respective through hole conductors 13, 15, 17, 19, 21, 22, 55 and 56 are formed to be components formed by sintering a conductive paste containing the aforementioned conductor material.
The discharge inducing portions 24 and 25 are formed to contain a material, out of Fe2O3, NiO, CuO, ZnO, MgO, SiO, TiO2, Mn2O3, SrO, CaO, BaO, SnO2, K2O, Al2O3, ZrO2, B2O3 and the like. The discharge inducing portions 24 and 25 may be also formed to contain a material made of a mixture of two or more types of materials out of them. The discharge inducing portions 24 and 25 contain metal particles formed from Ag, Pd, Au, Pt, an Ag/Pd alloy, an Ag/Cu alloy, an Ag/Au alloy, an Ag/Pt alloy, or the like. The metal material contained as the metal particles in the discharge inducing portions 24 and 25 may have a higher melting point than that of the conductor material contained in the respective conductors 51 to 54 forming the coils L1 and L2. The discharge inducing portions 24 and 25 preferably contain semiconductor particles made of RuO2 and the like. The discharge inducing portions 24 and 25 may also contain a glass or a lead oxide (SnO or SnO2).
Next, with reference to FIG. 6, a method for manufacturing an ESD Protection component according to the present embodiment will be described. FIG. 6 is a flow chart illustrating the method for manufacturing the ESD Protection component according to the present embodiment.
At first, slurry of materials to form the insulator layers 11 is prepared (S1), and green sheets for the insulator layers 11 are formed (S2). More specifically, a predetermined amount of a dielectric powder containing a copper oxide (CuO), and an organic vehicle containing an organic solvent and an organic binder are mixed to prepare slurry for the insulator layers 11. As the dielectric powder, it is possible to employ a dielectric material containing an oxide of Mg, Cu, Zn, Si or Sr (or other dielectric materials), as a main ingredient. Thereafter, the slurry is adhered to PET films, through a doctor blade process and the like, to form green sheets with a thickness of about 20 micrometers. Further, through holes have been formed therein through laser processing, at positions where the respective through hole conductors 13, 15, 17, 19, 21, 22, 55 and 56 are to be formed in the respective insulator layers 11.
After the green sheets for the insulator layers 11 have been formed, discharge-inducing-material slurry, a conductor paste, and a solvent (lacquer for cavitys) are adhered, through printing, to these green sheets at predetermined positions (S3). The printing of the discharge-inducing-material slurry is performed by preparing the discharge-inducing-material slurry for forming the discharge inducing portions 24 and 25 after firing and, further, applying this discharge-inducing-material slurry to the sheets for the insulator layers 11 (S3A). More specifically, respective powders of a tin oxide, an insulator and a conductor in predetermined amounts which have been measured, and an organic vehicle containing an organic solvent and an organic binder are mixed to prepare the discharge-inducing-material slurry. For example, it is possible to employ SnO2 for industrial purpose as the tin oxide, and it is possible to employ a dielectric powder as the insulator. As the dielectric powder, it is possible to employ a dielectric material containing an oxide of Mg, Cu, Zn, Si or Sr (or other dielectric materials), as a main ingredient. As the conductor powder, it is possible to employ an Ag/Pd powder (or Ag, Pd, Au, Pt or a mixture or a compound of them). The respective powders are sufficiently mixed into a state where the tin-oxide particles and the Ag/Pd-alloy metal particles are mingled with each other. The discharge-inducing-material slurry is to form the discharge inducing portions 24 and 25, through firing processing which will be described later.
The printing of the conductor paste is performed by applying the conductor paste for forming conductor patterns, to the green sheets for the insulator layers 11, through screen printing and the like (S3B). The conductor patterns are to form the respective conductors 51 to 54, the opposite electrodes 12, 14, 16 and 18 and the ground electrode 20, through the firing processing which will be described later. The respective conductor patterns are formed by drying the conductor paste after the screen printing. The conductor paste is filled into the through holes, during the formation of the respective conductor patterns. The conductor paste filled in the through holes is to form the respective through hole conductors 13, 15, 17, 19, 21, 22, 55 and 56, through the firing processing which will be described later.
The printing of the cavity lacquer is performed by applying the cavity lacquer to the green sheets for the insulator layers 11, such that it is overlaid on the conductor paste for forming the first opposite portion 12b of the opposite electrode 12 and the second opposite portion 20c of the ground electrode 20 which have been already printed, the conductor paste for forming the first opposite portion 14b of the opposite electrode 14 and the second opposite portion 20c of the ground electrode 20 which have been already printed, the conductor paste for forming the first opposite portion 16b of the opposite electrode 16 and the second opposite portion 20d of the ground electrode 20 which have been already printed, and the conductor paste for forming the first opposite portion 18b of the opposite electrode 18 and the second opposite portion 20d of the ground electrode 20 which have been already printed (S3C). The cavity lacquer is a coating material for forming the cavity portions 26, 27, 28 and 29.
The green sheets for the insulator layers 11, on which the discharge-inducing-material slurry, the conductor paste and the cavity lacquer have been adhered through printing, are stacked in order (S4), then pressing is applied thereto (S5), to obtain a multilayer body of the green sheet, and this multilayer body is cut into sizes corresponding to those of individual ESD protection component 1 (S6). The stacking of the green sheets for the insulator layers 11 is arranged, such that the respective structures to be formed after the firing are in the order of the respective conductors 51 to 54, the discharge inducing portions 24 and 25, the first extraction portions 12a, 14a, 16a and 18a and the second extraction portions 20a and 20b, the first opposite portions 12b, 14b, 16b and 18b and the second opposite portions 20c and 20d, and the cavity portions 26 to 29, in the stack direction, from the side closer to the side surface 4c of the element body 4, which is the surface to be mounted on the circuit board.
Subsequently, barrel polishing is performed on the respective green chips created by cutting the multilayer body of the green sheets for the insulator layers 11 (S7). This results in formation of green chips having rounded corner portions and rounded ridge lines.
Next, after the barrel polishing process, the green chips are fired in predetermined conditions (for example, for 2 hours at 850 to 950 degrees C in the atmosphere) (S8). Thus, the green chips are formed into the element bodies 4 through the firing. This results in formation of the first discharging portion GP1 between the first opposite portion 12b and the second opposite portion 20c, the second discharging portion GP2 between the first opposite portion 14b and the second opposite portion 20c, the third discharging portion GP3 between the first opposite portion 16b and the second opposite portion 20d, and the fourth discharging portion GP4 between the first opposite portion 18b and the second opposite portion 20d. Further, during the firing process, the cavity lacquer is vanished, thereby forming the cavity portion 26 covering the first discharging portion GP1, the cavity portion 27 covering the second discharging portion GP2, the cavity portion 28 covering the third discharging portion GP3, and the cavity portion 29 covering the fourth discharging portion GP4. Namely, through the firing process, it is possible to provide an intermediate member including the first discharging portion GP1, the second discharging portion GP2, the third discharging portion GP3, and the fourth discharging portion GP4.
Subsequently, a conductor paste for the external electrodes 5 to 10 is applied to the element bodies 4 (S9), and thermal treatment is performed thereon under predetermined conditions (for example, for 2 hours at 600 to 800 degrees C in the atmosphere) to sinter the conductor paste for forming the external electrodes 5 to 10 (S10). Thereafter, plating is applied to the surfaces of the external electrodes 5 to 10 (S11). The plating is preferably electrolytic plating and, for example, it is possible to employ Ni/Sn, Cu/Ni/Sn, Ni/Pd/Au, Ni/Pd/Ag, Ni/Ag and the like.
Through the aforementioned processes, it is possible to provide an ESD protection component 1A.
As described above, in the ESD protection component 1A according to the present embodiment, the first extraction portions 12a, 14a, 16a and 18a of the opposite electrodes 12, 14, 16 and 18, and the first opposite portions 12b, 14b, 16b and 18b of the opposite electrodes 12, 14, 16 and 18 are placed on the respective different layers and, further, are electrically connected to each other via the through hole conductors 13, 15, 17 and 19. The second extraction portions 20a and 20b of the ground electrode 20 and the second opposite portions 20c and 20d of the ground electrode 20 are placed on the respective different layers and, further, are electrically connected to each other via the through hole conductors 21 and 22. This makes the total area of the electrodes existing on the same layer smaller. This can enhance the adherence between the insulator layers 11, which can reduce the possibility of occurrences of structural defects, thereby suppressing the infiltration of the plating solution through such defects. This can suppress the infiltration of the plating solution into the first discharging portion GP1 formed between the first opposite portion 12b of the opposite electrode 12 and the second opposite portion 20c of the ground electrode 20, the second discharging portion GP2 formed between the first opposite portion 14b of the opposite electrode 14 and the second opposite portion 20d of the ground electrode 20, the third discharging portion GP3 formed between the first opposite portion 16b of the opposite electrode 16 and the second opposite portion 20d of the ground electrode 20, and the fourth discharging portion GP4 formed between the first opposite portion 18b of the opposite electrode 18 and the second opposite portion 20d of the ground electrode 20. Particularly, in the present embodiment, the first extraction portions 12a, 14a, 16a and 18a of the opposite electrodes 12, 14, 16 and 18 and the second extraction portions 20a and 20b of the ground electrode 20 are all placed on a different layer from the layer on which the first opposite portions 12b, 14b, 16b and 18b and the second opposite portions 20c and 20d are placed, which can reduce the total area of the electrodes existing on the same layer as much as possible, thereby certainly suppressing the infiltration of the plating solution into the discharging portions for inducing discharge.
Second Embodiment
Next, with reference to FIGS. 1, 2 and 7 to 9, the structure of an ESD protection component according to a second embodiment will be described. FIG. 7 is an exploded perspective view illustrating the structure of a portion including first to fourth discharging portions in a element body according to the second embodiment. FIG. 8 is a view illustrating the structure of a cross section including the first discharging portion and the third discharging portion in the ESD protection component according to the second embodiment. FIG. 9 is a view illustrating the structure of a cross section including the second discharging portion and the fourth discharging portion in the ESD protection component according to the second embodiment.
The ESD protection component LB according to the second embodiment includes a element body 4, external electrodes 5 to 10, and coils L1 and L2, similarly to the ESD protection component 1A according to the first embodiment. The element body 4, the external electrodes 5 to 10 and the coils L1 and L2 have the same structures as those in the first embodiment (see FIGS. 1 and 2). As illustrated in FIGS. 7 to 9, in the ESD protection component 1B according to the second embodiment, the portion including the first to fourth discharging portions has a different structure from that of the ESD protection component 1A according to the first embodiment. More specifically, instead of the opposite electrodes 12, 14, 16 and 18, the ground electrode 20, the first discharging portion GP1, the second discharging portion GP2, the third discharging portion GP3 and the fourth discharging portion GP4, the discharge inducing portions 24 and 25, and the cavity portions 26 to 29, the ESD protection component 1B includes opposite electrodes 30, 31, 32 and 33, a ground electrode 34, a first discharging portion GP5, a second discharging portion GP6, a third discharging portion GP7 and a fourth discharging portion GP8, discharge inducing portions 36 to 39, and cavity portions 40 to 43.
The opposite electrode 30 is placed at a position closer to the end surface 4a than to the end surface 4b in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4e than to the side surface 4f in the widthwise direction of the element body 4. The opposite electrode 30 has an L shape. The opposite electrode 30 has a first extraction portion 30a and a first opposite portion 30b. The first extraction portion 30a and the first opposite portion 30b are placed on the same insulator layer 11. The first extraction portion 30a extends in the widthwise direction of the element body 4. The first extraction portion 30a has an end portion 30c which is exposed in the side surface 4e of the element body 4 and is connected to the external electrode 5. The first opposite portion 30b extends in the longitudinal direction of the element body 4.
The opposite electrode 31 is placed at a position closer to the end surface 4b than to the end surface 4a in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4e than to the side surface 4f in the widthwise direction of the element body 4. The opposite electrode 31 has an L shape. The opposite electrode 31 has a first extraction portion 31a and a first opposite portion 31b. The first extraction portion 31a and the first opposite portion 31b are both placed on the same insulator layer 11 as the layer on which the first opposite portion 30b of the opposite electrode 30 is placed. Namely, the first extraction portion 31a and the first opposite portion 31b are placed on the same insulator layer 11. The first extraction portion 31a extends in the widthwise direction of the element body 4. The first extraction portion 31a has an end portion 31c which is exposed in the side surface 4e of the element body 4 and is connected to the external electrode 7. The first opposite portion 31b extends in the longitudinal direction of the element body 4.
The opposite electrode 32 is placed at a position closer to the end surface 4a than to the end surface 4b in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4f than to the side surface 4e in the widthwise direction of the element body 4. The opposite electrode 32 has an L shape. The opposite electrode 32 has a first extraction portion 32a and a first opposite portion 32b. The first extraction portion 32a and the first opposite portion 32b are both placed on the same insulator layer 11 as the layer on which the first opposite portion 30b of the opposite electrode 30 is placed. Namely, the first extraction portion 32a and the first opposite portion 32b are placed on the same insulator layer 11. The first extraction portion 32a extends in the widthwise direction of the element body 4. The first extraction portion 32a has an end portion 32c which is exposed in the side surface 4f of the element body 4 and is connected to the external electrode 6. The first opposite portion 32b extends in the longitudinal direction of the element body 4.
The opposite electrode 33 is placed at a position closer to the end surface 4b than to the end surface 4a in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4f than to the side surface 4e in the widthwise direction of the element body 4. The opposite electrode 33 has an L shape. The opposite electrode 33 has a first extraction portion 33a and a first opposite portion 33b. The first extraction portion 33a and the first opposite portion 33b are both placed on the same insulator layer 11 as the layer on which the first opposite portion 30b of the opposite electrode 30 is placed. Namely, the first extraction portion 33a and the first opposite portion 33b are placed on the same insulator layer 11. The first extraction portion 33a extends in the widthwise direction of the element body 4. The first extraction portion 33a has an end portion 33c which is exposed in the side surface 4f of the element body 4 and is connected to the external electrode 8. The first opposite portion 33b extends in the longitudinal direction of the element body 4.
The ground electrode 34 includes a second extraction portion 34a, a second opposite portion 34b and a second opposite portion 34c. The second extraction portion 34a is placed on a different insulator layer 11 from the layer on which the first opposite portion 30b of the opposite electrode 30 is placed, and the second opposite portion 34b and the second opposite portion 34c are placed on the same insulator layer 11 as the layer on which the first opposite portion 30b of the opposite electrode 30 is placed. Namely, the second extraction portion 34a, and the second opposite portion 34b and the second opposite portion 34c are placed on the respective different insulator layers 11.
The second extraction portion 34a is placed at a substantially-center position in the widthwise direction of the element body 4 and is extended in the longitudinal direction of the element body 4. The second extraction portion 34a has an end portion 34e which is exposed in the end surface 4a of the element body 4 and is connected to the external electrode 9. The second extraction portion 34a also has an end portion 34f which is exposed in the end surface 4b of the element body 4 and is connected to the external electrode 10.
The second opposite portion 34b and the second opposite portion 34c are spaced apart from each other and are extended in the longitudinal direction of the element body 4. A substantially-center portion of the second opposite portion 34b in the direction of the extension thereof and a substantially-center portion of the second opposite portion 34c in the direction of the extension thereof are connected to each other to form a connection portion 34d. The connection portion 34d extends in the widthwise direction of the element body 4. The connection portion 34d is electrically connected to the second extraction portion 34a via a through hole conductor 35. Thus, the second opposite portion 34b and the second opposite portion 34c are electrically connected to the second extraction portion 34a via the through hole conductor 35. The second opposite portion 34b, the second opposite portion 34c and the connection portion 34d form an H-shaped conductor pattern on the same insulator layer 11.
The side surface 4e (the exterior surface of the element body 4) has a region in which the first extraction portion 30a and the first extraction portion 31a are exposed. The second opposite portion 34b is placed at a position closer to the region in which the first extraction portion 30a and the first extraction portion 31a are exposed, than the first opposite portion 30b of the opposite electrode 30 and the first opposite portion 31b of the opposite electrode 31. Namely, the first opposite portions 30b and 31b are placed to be spaced apart from the side surface 4e of the element body 4 more largely than the second opposite portion 34b. The length of the first extraction portion 30a from the side surface 4e of the element body 4 to the first opposite portion 30b is namely the distance from the portion of the opposite electrode 30 which is exposed in the side surface 4e of the element body 4 to the first opposite portion 30b. The length of the first extraction portion 31a from the side surface 4e of the element body 4 to the first opposite portion 31b is namely the distance from the portion of the opposite electrode 31 which is exposed in the side surface 4e of the element body 4 to the first opposite portion 31b. 
The second opposite portion 34b is placed to face the first opposite portion 30b of the opposite electrode 30 and the first opposite portion 31b of the opposite electrode 31, in such a way as to be spaced apart therefrom. Thus, the first discharging portion GP5 is formed between the first opposite portion 30b of the opposite electrode 30 and the second opposite portion 34b of the ground electrode 34 (see FIG. 8), and the second discharging portion GP6 is formed between the first opposite portion 31b of the opposite electrode 31 and the second opposite portion 34b of the ground electrode 34 (see FIG. 9). With this structure, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 5 and the external electrode 9, discharging is induced in the first discharging portion GP5. Similarly, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 7 and the external electrode 10, discharging is induced in the second discharging portion GP6.
The side surface 4f (the exterior surface of the element body 4) has a region in which the first extraction portion 32a and the first extraction portion 33a are exposed. The second opposite portion 34c is placed at a position closer to the region in which the first extraction portion 32a and the first extraction portion 33a are exposed, than the first opposite portion 32b of the opposite electrode 32 and the first opposite portion 33b of the opposite electrode 33. Namely, the first opposite portions 32b and 33b are placed to be spaced apart from the side surface 4f of the element body 4 more largely than the second opposite portion 34c. The length of the first extraction portion 32a from the side surface 4f of the element body 4 to the first opposite portion 32b is namely the distance from the portion of the opposite electrode 32 which is exposed in the side surface 4f of the element body 4 to the first opposite portion 32b. The length of the first extraction portion 33a from the side surface 4f of the element body 4 to the first opposite portion 33b is namely the distance from the portion of the opposite electrode 33 which is exposed in the side surface 4f of the element body 4 to the first opposite portion 33b. 
The second opposite portion 34c is placed to face the first opposite portion 32b of the opposite electrode 32 and the first opposite portion 33b of the opposite electrode 33, in such a way as to be spaced apart therefrom. Thus, the third discharging portion GP7 is formed between the first opposite portion 32b of the opposite electrode 32 and the second opposite portion 34c of the ground electrode 34 (see FIG. 8), and the fourth discharging portion GP8 is formed between the first opposite portion 33b of the opposite electrode 33 and the second opposite portion 34c of the ground electrode 34 (see FIG. 9). With this structure, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 6 and the external electrode 9, discharging is induced in the third discharging portion GP7. Similarly, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 8 and the external electrode 10, discharging is induced in the fourth discharging portion GP8.
The discharge inducing portion 36 is positioned for the first discharging portion GP5 and has the function of facilitating the occurrence of discharge in the first discharging portion GP5. The discharge inducing portion 36 connects the first opposite portion 30b of the opposite electrode 30 to the second opposite portion 34b of the ground electrode 34. The discharge inducing portion 37 is positioned for the second discharging portion GP6 and has the function of facilitating the occurrence of discharge in the second discharging portion GP6. The discharge inducing portion 37 connects the first opposite portion 31b of the opposite electrode 31 to the second opposite portion 34b of the ground electrode 34.
The discharge inducing portion 38 is positioned for the third discharging portion GP7 and has the function of facilitating the occurrence of discharge in the third discharging portion GP7. The discharge inducing portion 38 connects the first opposite portion 32b of the opposite electrode 32 to the second opposite portion 34c of the ground electrode 34. The discharge inducing portion 39 is positioned for the fourth discharging portion GP8 and has the function of facilitating the occurrence of discharge in the fourth discharging portion GP8. The discharge inducing portion 39 connects the first opposite portion 33b of the opposite electrode 33 to the second opposite portion 34c of the ground electrode 34.
The cavity portion 40 is formed for the first discharging portion GP5. The cavity portion 40 has the function of absorbing thermal expansions of the first opposite portion 30b, the second opposite portion 34b, the insulator layer 11 and the discharge inducing portion 36 during discharging. The cavity portion 41 is formed for the second discharging portion GP6. The cavity portion 41 has the function of absorbing thermal expansions of the first opposite portion 31b, the second opposite portion 34b, the insulator layer 11 and the discharge inducing portion 37 during discharging. The cavity portion 42 is formed for the third discharging portion GP7. The cavity portion 42 has the function of absorbing thermal expansions of the first opposite portion 32b, the second opposite portion 34c, the insulator layer 11 and the discharge inducing portion 38, during discharging. The cavity portion 43 is formed for the fourth discharging portion GP8. The cavity portion 43 has the function of absorbing thermal expansions of the first opposite portion 33b, the second opposite portion 34c, the insulator layer 11 and the discharge inducing portion 39, during discharging.
As described above, the ESD protection component 1B according to the present embodiment also offers the same effects as those of the aforementioned embodiment. Namely, the second extraction portion 34a and the second opposite portions 34b and 34c of the ground electrode 34, in the opposite electrodes 30, 31, 32 and 33 and the ground electrode 34, are placed on the respective different layers and are electrically connected to each other via the through hole conductor 35. This makes the total area of the electrodes existing on the same layer smaller. This can enhance the adherence between the insulator layers 11, which can reduce the possibility of occurrences of structural defects, thereby suppressing the infiltration of the plating solution through such defects. This can suppress the infiltration of the plating solution into the first discharging portion GP5 formed between the first opposite portion 30b of the opposite electrode 30 and the second opposite portion 34b of the ground electrode 34, the second discharging portion GP6 formed between the first opposite portion 31b of the opposite electrode 31 and the second opposite portion 34b of the ground electrode 34, the third discharging portion GP7 formed between the first opposite portion 32b of the opposite electrode 32 and the second opposite portion 34c of the ground electrode 34, and the fourth discharging portion GP8 formed between the first opposite portion 33b of the opposite electrode 33 and the second opposite portion 34c of the ground electrode 34.
Particularly, in the present embodiment, the second extraction portion 34a of the ground electrode 34 is placed on the other layer than the layer on which the first opposite portions 30b, 31b, 32b and 33b of the opposite electrodes 30, 31, 32 and 33 and the second opposite portions 34b and 34c of the ground electrode 34 are placed, which enables freely determining the conductor patterns of the first opposite portions 30b, 31b, 32b and 33b and the second opposite portions 34b and 34c, regardless of the conductor pattern of the second extraction portion 34a, in the layer on which the first opposite portions 30b, 31b, 32b and 33b and the second opposite portions 34b and 34c are placed.
Further, the side surface 4e (the exterior surface of the element body 4) has a region in which the first extraction portion 30a connected to the first opposite portion 30b and the first extraction portion 31a connected to the first opposite portion 31b are exposed. The second opposite portion 34b is placed at a position closer to the region in which the first extraction portion 30a connected to the first opposite portion 30b and the first extraction portion 31a connected to the first opposite portion 31b are exposed, than the first opposite portion 30b of the opposite electrode 30 and the first opposite portion 31b of the opposite electrode 31. The side surface 4f(the exterior surface of the element body 4) has a region in which the first extraction portion 32a connected to the first opposite portion 32b and the first extraction portion 33a connected to the first opposite portion 33b are exposed. The second opposite portion 34c is placed at a position closer to the region in which the first extraction portion 32a connected to the first opposite portion 32b and the first extraction portion 33a connected to the first opposite portion 33b are exposed, than the first opposite portion 32b of the opposite electrode 32 and the first opposite portion 33b of the opposite electrode 33. Namely, the first opposite portions 30b and 31b are placed to be spaced apart from the side surface 4e of the element body 4 more largely than the second opposite portion 34b, and the first opposite portions 32b and 33b are placed to be spaced apart from the side surface 4f of the element body 4 more largely than the second opposite portion 34c. This increases the lengths of the opposite electrodes 30 to 33 from their portions exposed in the side surfaces 4e and 4f of the element body 4 to the first opposite portion 30b, 31b, 32b and 33b, which can inhibit the plating solution having entered through these exposed portions from infiltrating into the first opposite portions 30b, 31b, 32b and 33b. This can suppress the infiltration of the plating solution into the first discharging portion GP5, the second discharging portion GP6, the third discharging portion GP7 and the fourth discharging portion GP8.
Third Embodiment
Next, with reference to FIGS. 1, 2 and 10 to 12, the structure of an ESD protection component according to a third embodiment will be described. FIG. 10 is an exploded perspective view illustrating the structure of a portion including first to fourth discharging portions in a element body according to the third embodiment. FIG. 11 is a view illustrating the structure of a cross section including the first discharging portion and the third discharging portion in the ESD protection component according to the third embodiment. FIG. 12 is a view illustrating the structure of a cross section including the second discharging portion and the fourth discharging portion in the ESD protection component according to the third embodiment.
The ESD protection component 1C according to the third embodiment includes an element body 4, external electrodes 5 to 10, and coils L1 and L2, similarly to the ESD protection component 1A according to the first embodiment. The element body 4, the external electrodes 5 to 10 and the coils L1 and L2 have the same structures as those in the first embodiment (see FIGS. 1 and 2). As illustrated in FIGS. 10 to 12, in the ESD protection component 1C according to the third embodiment, the portion including the first to fourth discharging portions has a different structure from that of the ESD protection component 1A according to the first embodiment, similarly to in the ESD protection component 1B according to the second embodiment. More specifically, instead of the opposite electrodes 12, 14, 16 and 18, the ground electrode 20, the first discharging portion GP1, the second discharging portion GP2, the third discharging portion GP3 and the fourth discharging portion GP4, the discharge inducing portions 24 and 25, and the cavity portions 26 to 29, the ESD protection component 1C includes opposite electrodes 60, 62, 64 and 66, a ground electrode 68, a first discharging portion GP9, a second discharging portion GP10, a third discharging portion GP1 and a fourth discharging portion GP12, discharge inducing portions 70 to 73, and cavity portions 74 to 77.
The opposite electrode 60 is placed at a position closer to the end surface 4a than to the end surface 4b in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4e than to the side surface 4f in the widthwise direction of the element body 4. The opposite electrode 60 has a first extraction portion 60a and a first opposite portion 60b. The first extraction portion 60a and the first opposite portion 60b are placed on respective different insulator layers 11. The first extraction portion 60a extends in the widthwise direction of the element body 4. The first extraction portion 60a has an end portion 60c which is exposed in the side surface 4e of the element body 4 and is connected to the external electrode 5. The first opposite portion 60b has a portion extending in the longitudinal direction of the element body 4 and a portion extending in the widthwise direction of the element body 4. The portion of the first opposite portion 60b which extends in the widthwise direction of the element body 4 forms a connection portion 60d at its end. The connection portion 60d is electrically connected to the first extraction portion 60a via a through hole conductor 61. Thus, the first opposite portion 60b is electrically connected to the first extraction portion 60a via the through hole conductor 61.
The opposite electrode 62 is placed at a position closer to the end surface 4b than to the end surface 4a in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4e than to the side surface 4f in the widthwise direction of the element body 4. The opposite electrode 62 has a first extraction portion 62a and a first opposite portion 62b. The first extraction portion 62a is placed on a different insulator layer 11 from the layer on which the first opposite portion 60b of the opposite electrode 60 is placed, and the first opposite portion 62b is placed on the same insulator layer 11 as the layer on which the first opposite portion 60b of the opposite electrode 60 is placed. Namely, the first extraction portion 62a and the first opposite portion 62b are placed on the respective different insulator layers 11. The first extraction portion 62a extends in the widthwise direction of the element body 4. The first extraction portion 62a has an end portion 62c which is exposed in the side surface 4e of the element body 4 and is connected to the external electrode 7. The first opposite portion 62b has a portion extending in the longitudinal direction of the element body 4 and a portion extending in the widthwise direction of the element body 4. The portion of the first opposite portion 62b which extends in the widthwise direction of the element body 4 forms a connection portion 62d at its end. The connection portion 62d is electrically connected to the first extraction portion 62a via a through hole conductor 63. Thus, the first opposite portion 62b is electrically connected to the first extraction portion 62a via the through hole conductor 63.
The opposite electrode 64 is placed at a position closer to the end surface 4a than to the end surface 4b in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4f than to the side surface 4e in the widthwise direction of the element body 4. The opposite electrode 64 has a first extraction portion 64a and a first opposite portion 64b. The first extraction portion 64a is placed on a different insulator layer 11 from the layer on which the first opposite portion 60b of the opposite electrode 60 is placed, and the first opposite portion 64b is placed on the same insulator layer 11 as the layer on which the first opposite portion 60b of the opposite electrode 60 is placed. Namely, the first extraction portion 64a and the first opposite portion 64b are placed on the respective different insulator layers 11. The first extraction portion 64a extends in the widthwise direction of the element body 4. The first extraction portion 64a has an end portion 64c which is exposed in the side surface 4f of the element body 4 and is connected to the external electrode 6. The first opposite portion 64b has a portion extending in the longitudinal direction of the element body 4 and a portion extending in the widthwise direction of the element body 4. The portion of the first opposite portion 64b which extends in the widthwise direction of the element body 4 forms a connection portion 64d at its one end. The connection portion 64d is electrically connected to the first extraction portion 64a via a through hole conductor 65. Thus, the first opposite portion 64b is electrically connected to the first extraction portion 64a via the through hole conductor 65.
The opposite electrode 66 is placed at a position closer to the end surface 4b than to the end surface 4a in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4f than to the side surface 4e in the widthwise direction of the element body 4. The opposite electrode 66 has a first extraction portion 66a and a first opposite portion 66b. The first extraction portion 66a is placed on a different insulator layer 11 from the layer on which the first opposite portion 60b of the opposite electrode 60 is placed, and the first opposite portion 66b is placed on the same insulator layer 11 as the layer on which the first opposite portion 60b of the opposite electrode 60 is placed. Namely, the first extraction portion 66a and the first opposite portion 66b are placed on the respective different insulator layers 11. The first extraction portion 66a extends in the widthwise direction of the element body 4. The first extraction portion 66a has an end portion 66c which is exposed in the side surface 4f of the element body 4 and is connected to the external electrode 8. The first opposite portion 66b has a portion extending in the longitudinal direction of the element body 4 and a portion extending in the widthwise direction of the element body 4. The portion of the first opposite portion 66b which extends in the widthwise direction of the element body 4 forms a connection portion 66d at its end. The connection portion 66d is electrically connected to the first extraction portion 66a via a through hole conductor 67. Thus, the first opposite portion 66b is electrically connected to the first extraction portion 66a via the through hole conductor 67.
The ground electrode 68 includes a second extraction portion 68a, a second opposite portion 68b and a second opposite portion 68c. The second extraction portion 68a is placed on a different insulator layer 11 from the layer on which the first opposite portion 60b of the opposite electrode 60 is placed, and the second opposite portion 68b and the second opposite portion 68c are placed on the same insulator layer 11 as the layer on which the first opposite portion 60b of the opposite electrode 60 is placed. Namely, the second extraction portion 68a, and the second opposite portion 68b and the second opposite portion 68c are placed on the respective different insulator layers 11.
The second extraction portion 68a is placed at a substantially-center position in the widthwise direction of the element body 4 and is extended in the longitudinal direction of the element body 4. The second extraction portion 68a has an end portion 68e which is exposed in the end surface 4a of the element body 4 and is connected to the external electrode 9. The second extraction portion 68a also has an end portion 68f which is exposed in the end surface 4b of the element body 4 and is connected to the external electrode 10.
The second opposite portion 68b and the second opposite portion 68c are spaced apart from each other and are extended in the longitudinal direction of the element body 4. A substantially-center portion of the second opposite portion 68b in the direction of the extension thereof and a substantially-center portion of the second opposite portion 68c in the direction of the extension thereof are connected to each other to form a connection portion 68d. The connection portion 68d extends in the widthwise direction of the element body 4. The connection portion 68d is electrically connected to the second extraction portion 68a via a through hole conductor 69. Thus, the second opposite portion 68b and the second opposite portion 68c are electrically connected to the second extraction portion 68a via the through hole conductor 69. The second opposite portion 68b, the second opposite portion 68c and the connection portion 68d form an H-shaped conductor pattern on the same insulator layer 11.
The second opposite portion 68b is placed at a position closer to the side surface 4e, which is an exterior surface of the element body 4, than the first opposite portion 60b of the opposite electrode 60 and the first opposite portion 62b of the opposite electrode 62. Namely, the first opposite portions 60b and 62b are placed to be spaced apart from the side surface 4e of the element body 4 more largely than the second opposite portion 68b. The length of the first extraction portion 60a from the side surface 4e of the element body 4 to the first opposite portion 60b is namely the distance from the portion of the opposite electrode 60 which is exposed in the side surface 4e of the element body 4 to the first opposite portion 60b. The length of the first extraction portion 62a from the side surface 4e of the element body 4 to the first opposite portion 62b is namely the distance from the portion of the opposite electrode 62 which is exposed in the side surface 4e of the element body 4 to the first opposite portion 62b. 
The second opposite portion 68b is placed to face the first opposite portion 60b of the opposite electrode 60 and the first opposite portion 62b of the opposite electrode 62, in such a way as to be spaced apart therefrom. Thus, the first discharging portion GP9 is formed between the first opposite portion 60b of the opposite electrode 60 and the second opposite portion 68b of the ground electrode 68 (see FIG. 11), and the second discharging portion GP10 is formed between the first opposite portion 62b of the opposite electrode 62 and the second opposite portion 68b of the ground electrode 68 (see FIG. 12). With this structure, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 5 and the external electrode 9, discharging is induced in the first discharging portion GP9. Similarly, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 7 and the external electrode 10, discharging is induced in the second discharging portion GP10.
The second opposite portion 68c is placed at a position closer to the side surface 4f, which is an exterior surface of the element body 4, than the first opposite portion 64b of the opposite electrode 64 and the first opposite portion 66b of the opposite electrode 66. Namely, the first opposite portions 64b and 66b are placed to be spaced apart from the side surface 4f of the element body 4 more largely than the second opposite portion 68c. The length of the first extraction portion 64a from the side surface 4f of the element body 4 to the first opposite portion 64b is namely the distance from the portion of the opposite electrode 64 which is exposed in the side surface 4f of the element body 4 to the first opposite portion 64b. The length of the first extraction portion 66a from the side surface 4f of the element body 4 to the first opposite portion 66b is namely the distance from the portion of the opposite electrode 66 which is exposed in the side surface 4f of the element body 4 to the first opposite portion 66b. 
The second opposite portion 68c is placed to face the first opposite portion 64b of the opposite electrode 64 and the first opposite portion 66b of the opposite electrode 66, in such a way as to be spaced apart therefrom. Thus, the third discharging portion GP11 is formed between the first opposite portion 64b of the opposite electrode 64 and the second opposite portion 68c of the ground electrode 68 (see FIG. 11), and the fourth discharging portion GP12 is formed between the first opposite portion 64b of the opposite electrode 64 and the second opposite portion 68c of the ground electrode 68 (see FIG. 12). With this structure, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 6 and the external electrode 9, discharging is induced in the third discharging portion GP11. Similarly, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 8 and the external electrode 10, discharging is induced in the fourth discharging portion GP12.
The discharge inducing portion 70 is positioned for the first discharging portion GP9 and has the function of facilitating the occurrence of discharge in the first discharging portion GP9. The discharge inducing portion 70 connects the first opposite portion 60b of the opposite electrode 60 to the second opposite portion 68b of the ground electrode 68. The discharge inducing portion 71 is positioned for the second discharging portion GP10 and has the function of facilitating the occurrence of discharge in the second discharging portion GP10. The discharge inducing portion 71 connects the first opposite portion 62b of the opposite electrode 62 to the second opposite portion 68b of the ground electrode 68.
The discharge inducing portion 72 is positioned for the third discharging portion GP11 and has the function of facilitating the occurrence of discharge in the third discharging portion GP11. The discharge inducing portion 72 connects the first opposite portion 64b of the opposite electrode 64 to the second opposite portion 68c of the ground electrode 68. The discharge inducing portion 73 is positioned for the fourth discharging portion GP12 and has the function of facilitating the occurrence of discharge in the fourth discharging portion GP12. The discharge inducing portion 73 connects the first opposite portion 66b of the opposite electrode 66 to the second opposite portion 68c of the ground electrode 68.
The cavity portion 74 is formed for the first discharging portion GP9. The cavity portion 74 has the function of absorbing thermal expansions of the first opposite portion 60b, the second opposite portion 68b, the insulator layer 11 and the discharge inducing portion 70 during discharging. The cavity portion 75 is formed for the second discharging portion GP10. The cavity portion 75 has the function of absorbing thermal expansions of the first opposite portion 62b, the second opposite portion 68b, the insulator layer 11 and the discharge inducing portion 71 during discharging. The cavity portion 76 is formed for the third discharging portion GP11. The cavity portion 76 has the function of absorbing thermal expansions of the first opposite portion 64b, the second opposite portion 68c, the insulator layer 11 and the discharge inducing portion 72, during discharging. The cavity portion 77 is formed for the fourth discharging portion GP12. The cavity portion 77 has the function of absorbing thermal expansions of the first opposite portion 66b, the second opposite portion 68c, the insulator layer 11 and the discharge inducing portion 73, during discharging.
As described above, the ESD protection component 1C according to the present embodiment also offers the same effects as those of the aforementioned embodiments.
Fourth Embodiment
Next, with reference to FIGS. 1, 2 and 13 to 15, the structure of a ESD protection component according to a fourth embodiment will be described. FIG. 13 is an exploded perspective view illustrating the structure of a portion including first to fourth discharging portions in a element body according to the fourth embodiment. FIG. 14 is a view illustrating the structure of a cross section including the first discharging portion and the third discharging portion in the ESD protection component according to the fourth embodiment. FIG. 15 is a view illustrating the structure of a cross section including the second discharging portion and the fourth discharging portion in the ESD protection component according to the fourth embodiment.
The ESD protection component 1D according to the fourth embodiment includes an element body 4, external electrodes 5 to 10, and coils L1 and L2, similarly to the ESD protection component 1A according to the first embodiment. The element body 4, the external electrodes 5 to 10 and the coils L1 and L2 have the same structures as those in the first embodiment (see FIGS. 1 and 2). As illustrated in FIGS. 13 to 15, in the ESD protection component 1D according to the fourth embodiment, the portion including the first to fourth discharging portions has a different structure from that of the ESD protection component 1A according to the first embodiment, similarly to in the ESD protection component 1B and 1C according to the second and third embodiments. More specifically, instead of the opposite electrodes 12, 14, 16 and 18, the ground electrode 20, the first discharging portion GP1, the second discharging portion GP2, the third discharging portion GP3 and the fourth discharging portion GP4, the discharge inducing portions 24 and 25, and the cavity portions 26 to 29, the ESD protection component 1D includes opposite electrodes 78, 79, 80 and 81, a ground electrode 82, a first discharging portion GP13, a second discharging portion GP14, a third discharging portion GP15 and a fourth discharging portion GP16, discharge inducing portions 85 to 88, and cavity portions 89 to 92.
The opposite electrode 78 is placed at a position closer to the end surface 4a than to the end surface 4b in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4f than to the side surface 4e in the widthwise direction of the element body 4. The opposite electrode 78 has an L shape. The opposite electrode 78 has a first extraction portion 78a and a first opposite portion 78b. The first extraction portion 78a and the first opposite portion 78b are placed on the same insulator layer 11. The first extraction portion 78a extends in the widthwise direction of the element body 4. The first extraction portion 78a has an end portion 78c which is exposed in the side surface 4f of the element body 4 and is connected to the external electrode 6. The first opposite portion 78b extends in the longitudinal direction of the element body 4.
The opposite electrode 79 is placed at a position closer to the end surface 4b than to the end surface 4a in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4e than to the side surface 4f in the widthwise direction of the element body 4. The opposite electrode 79 has an L shape. The opposite electrode 79 has a first extraction portion 79a and a first opposite portion 79b. The first extraction portion 79a and the first opposite portion 79b are both placed on the same insulator layer 11 as the layer on which the first opposite portion 78b of the opposite electrode 78 is placed. Namely, the first extraction portion 79a and the first opposite portion 79b are placed on the same insulator layer 11. The first extraction portion 79a extends in the widthwise direction of the element body 4. The first extraction portion 79a has an end portion 79c which is exposed in the side surface 4e of the element body 4 and is connected to the external electrode 7. The first opposite portion 79b extends in the longitudinal direction of the element body 4.
The opposite electrode 80 is placed at a position closer to the end surface 4a than to the end surface 4b in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4e than to the side surface 4f in the widthwise direction of the element body 4. The opposite electrode 80 has an L shape. The opposite electrode 80 has a first extraction portion 80a and a first opposite portion 80b. The first extraction portion 80a and the first opposite portion 80b are both placed on a different insulator layer 11 from the layer on which the first extraction portion 78a and the first opposite portion 78b of the opposite electrode 78 are placed. The first extraction portion 80a and the first opposite portion 80b are placed on the same insulator layer 11. The first extraction portion 80a extends in the widthwise direction of the element body 4. The first extraction portion 80a has an end portion 80c which is exposed in the side surface 4e of the element body 4 and is connected to the external electrode 5. The first opposite portion 80b extends in the longitudinal direction of the element body 4.
The opposite electrode 81 is placed at a position closer to the end surface 4b than to the end surface 4a in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4f than to the side surface 4e in the widthwise direction of the element body 4. The opposite electrode 81 has an L shape. The opposite electrode 81 has a first extraction portion 81a and a first opposite portion 81b. The first extraction portion 81a and the first opposite portion 81b are both placed on the same insulator layer 11 as the layer on which the first opposite portion 80b of the opposite electrode 80 is placed. Namely, the first extraction portion 81a and the first opposite portion 81b are placed on the same insulator layer 11. The first extraction portion 81a extends in the widthwise direction of the element body 4. The first extraction portion 81a has an end portion 81c which is exposed in the side surface 4f of the element body 4 and is connected to the external electrode 8. The first opposite portion 81b extends in the longitudinal direction of the element body 4.
The ground electrode 82 includes a second extraction portion 82a, a second opposite portion 82b and a second opposite portion 82c. The second extraction portion 82a is placed on an insulator layer 11 which is different from the layer on which the first opposite portion 78b of the opposite electrode 78 is placed and, also, is different from the layer on which the first opposite portion 80b of the opposite electrode 80 is placed. The second opposite portion 82b is placed on the same insulator layer 11 as the layer on which the first opposite portion 79b of the opposite electrode 79 is placed. The second opposite portion 82c is placed on the same insulator layer 11 as the layer on which the first opposite portion 80b of the opposite electrode 80 is placed. Namely, the second extraction portion 82a, the second opposite portion 82b and the second opposite portion 82c are placed on the respective different insulator layers 11.
The second extraction portion 82a is placed at a substantially-center position in the widthwise direction of the bare body 4 and is extended in the longitudinal direction of the element body 4. The second extraction portion 82a has an end portion 82e which is exposed in the end surface 4a of the element body 4 and is connected to the external electrode 9. The second extraction portion 82a also has an end portion 82f which is exposed in the end surface 4b of the element body 4 and is connected to the external electrode 10.
The second opposite portion 82b extends in the longitudinal direction of the element body 4. The second opposite portion 82b is electrically connected to the second extraction portion 82a via a through hole conductor 83. The second opposite portion 82c extends in the longitudinal direction of the element body 4. The second opposite portion 82c is electrically connected to the second extraction portion 82a via a through hole conductor 84.
The side surface 4f (exterior surface of the element body 4) has a region in which the first extraction portion 78a is exposed. The second opposite portion 82b is placed at a position closer to the region in which the first extraction portion 78a is exposed, than the first opposite portion 78b of the opposite electrode 78. Namely, the first opposite portion 78b is placed to be spaced apart from the side surface 4f, which is an exterior surface of the element body 4, more largely than the second opposite portion 82b. The length of the first extraction portion 78a from the side surface 4f of the element body 4 to the first opposite portion 78b is namely the distance from the portion of the opposite electrode 78 which is exposed in the side surface 4f of the element body 4 to the first opposite portion 78b. 
The side surface 4e (the exterior surface of the element body 4) has a region in which the first extraction portion 79a is exposed. The second opposite portion 82b is placed at a position closer to the region in which the first extraction portion 79a is exposed, than the first opposite portion 79b of the opposite electrode 79. Namely, the first opposite portion 79b is placed to be spaced apart from the side surface 4e, which is an exterior surface of the element body 4, more largely than the second opposite portion 82b. The length of the first extraction portion 79a from the side surface 4e of the element body 4 to the first opposite portion 79b is namely the distance from the portion of the opposite electrode 79 which is exposed in the side surface 4e of the element body 4 to the first opposite portion 79b. 
The second opposite portion 82b is placed to face the first opposite portion 78b of the opposite electrode 78 and the first opposite portion 79b of the opposite electrode 79, in such a way as to be spaced apart therefrom. Thus, the first discharging portion GP13 is formed between the first opposite portion 78b of the opposite electrode 78 and the second opposite portion 82b of the ground electrode 82 (see FIG. 14), and the second discharging portion GP14 is formed between the first opposite portion 79b of the opposite electrode 79 and the second opposite portion 82b of the ground electrode 82 (see FIG. 15). With this structure, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 6 and the external electrode 9, discharging is induced in the first discharging portion GP13. Similarly, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 7 and the external electrode 10, discharging is induced in the second discharging portion GP14.
The side surface 4e (the exterior surface of the element body 4) has a region in which the first extraction portion 80a is exposed. The second opposite portion 82c is placed at a position closer to the region in which the first extraction portion 80a is exposed, than the first opposite portion 80b of the opposite electrode 80. Namely, the first opposite portion 80b is placed to be spaced apart from the side surface 4e, which is an exterior surface of the element body 4, more largely than the second opposite portion 82c. The length of the first extraction portion 80a from the side surface 4e of the element body 4 to the first opposite portion 80b is namely the distance from the portion of the opposite electrode 80 which is exposed in the side surface 4e of the element body 4 to the first opposite portion 80b. 
The side surface 4f (the exterior surface of the element body 4) has a region in which the first extraction portion 81a is exposed. The second opposite portion 82c is placed at a position closer to the region in which the first extraction portion 81a is exposed, than the first opposite portion 81b of the opposite electrode 81. Namely, the first opposite portion 81b is placed to be spaced apart from the side surface 4f, which is an exterior surface of the element body 4, more largely than the second opposite portion 82c. The length of the first extraction portion 81a from the side surface 4f of the element body 4 to the first opposite portion 81b is namely the distance from the portion of the opposite electrode 81 which is exposed in the side surface 4f of the element body 4 to the first opposite portion 81b. 
The second opposite portion 82c is placed to face the first opposite portion 80b of the opposite electrode 80 and the first opposite portion 81b of the opposite electrode 81, in such a way as to be spaced apart therefrom. Thus, the third discharging portion GP15 is formed between the first opposite portion 80b of the opposite electrode 80 and the second opposite portion 82c of the ground electrode 82 (see FIG. 14), and the fourth discharging portion GP16 is formed between the first opposite portion 81b of the opposite electrode 81 and the second opposite portion 82c of the ground electrode 82 (see FIG. 15). With this structure, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 5 and the external electrode 9, discharging is induced in the third discharging portion GP15. Similarly, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 8 and the external electrode 10, discharging is induced in the fourth discharging portion GP16.
The discharge inducing portion 85 is positioned for the first discharging portion GP13 and has the function of facilitating the occurrence of discharge in the first discharging portion GP13. The discharge inducing portion 85 connects the first opposite portion 78b of the opposite electrode 78 to the second opposite portion 82b of the ground electrode 82. The discharge inducing portion 86 is positioned for the second discharging portion GP14 and has the function of facilitating the occurrence of discharge in the second discharging portion GP14. The discharge inducing portion 86 connects the first opposite portion 79b of the opposite electrode 79 to the second opposite portion 82b of the ground electrode 82.
The discharge inducing portion 87 is positioned for the third discharging portion GP15 and has the function of facilitating the occurrence of discharge in the third discharging portion GP15. The discharge inducing portion 87 connects the first opposite portion 80b of the opposite electrode 80 to the second opposite portion 82c of the ground electrode 82. The discharge inducing portion 88 is positioned for the fourth discharging portion GP16 and has the function of facilitating the occurrence of discharge in the fourth discharging portion GP16. The discharge inducing portion 88 connects the first opposite portion 81b of the opposite electrode 81 to the second opposite portion 82c of the ground electrode 82.
The cavity portion 89 is formed for the first discharging portion GP13. The cavity portion 89 has the function of absorbing thermal expansions of the first opposite portion 78b, the second opposite portion 82b, the insulator layer 11 and the discharge inducing portion 85 during discharging. The cavity portion 90 is formed for the second discharging portion GP14. The cavity portion 90 has the function of absorbing thermal expansions of the first opposite portion 79b, the second opposite portion 82b, the insulator layer 11 and the discharge inducing portion 86 during discharging. The cavity portion 91 is formed for the third discharging portion GP11. The cavity portion 91 has the function of absorbing thermal expansions of the first opposite portion 80b, the second opposite portion 82c, the insulator layer 11 and the discharge inducing portion 87, during discharging. The cavity portion 92 is formed for the fourth discharging portion GP12. The cavity portion 92 has the function of absorbing thermal expansions of the first opposite portion 81b, the second opposite portion 82c, the insulator layer 11 and the discharge inducing portion 88, during discharging.
As described above, the ESD protection component 1D according to the present embodiment also offers the same effects as those of the aforementioned embodiments.
Fifth Embodiment
Next, with reference to FIGS. 1 and 16 to 18, the structure of an ESD protection component according to a fifth embodiment will be described. FIG. 16 is an exploded perspective view illustrating the structure of an element body according to the fifth embodiment. FIG. 17 is a view illustrating the structure of a cross section including a first discharging portion and a third discharging portion in the ESD protection component according to the fifth embodiment. FIG. 18 is a view illustrating the structure of a cross section including a second discharging portion and a fourth discharging portion in the ESD protection component according to the fifth embodiment.
The ESD protection component 1E according to the fifth embodiment includes an element body 4, external electrodes 5 to 10, and coils L1 and L2, similarly to the ESD protection component 1A according to the first embodiment. The element body 4, the external electrodes 5 to 10 and the coils L1 and L2 have the same structures as those in the first embodiment (see FIGS. 1 and 2). As illustrated in FIGS. 16 to 18, in the ESD protection component 1E according to the fifth embodiment, the structure of the portion including the first to fourth discharging portions is different from that of the ESD protection component 1A according to the first embodiment. More specifically, in the ESD protection component 1E according to the present embodiment, the positions of the first to fourth discharging portions are placed in both sides with respect to the coils L1 and L2 in the direction of layer lamination, while in the ESD protection component 1A, the positions of the first to fourth discharging portions are placed in one side with respect to the coils L1 and L2 in the stack direction of the plurality of insulator layers. Instead of the opposite electrodes 12, 14, 16 and 18, the ground electrode 20, the first discharging portion GP1, the second discharging portion GP2, the third discharging portion GP3 and the fourth discharging portion GP4, the discharge inducing portions 24 and 25, and the cavity portions 26 to 29 which are included in the ESD protection component 1A, the ESD protection component 1E includes opposite electrodes 93, 94, 95 and 96, ground electrodes 97 and 99, a first discharging portion GP17, a second discharging portion GP18, a third discharging portion GP19 and a fourth discharging portion GP20, discharge inducing portions 101 to 104, and cavity portions 105 to 108.
The opposite electrodes 93 and 94 are placed at a position closer to the side surface 4d of the element body 4, than the coils L1 and L2, in the stack of the plurality of insulator layers. The opposite electrode 93 is placed at a position closer to the end surface 4a than to the end surface 4b in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4e than to the side surface 4f in the widthwise direction of the element body 4. The opposite electrodes 93 have L shape. The opposite electrode 93 has a first extraction portion 93a and a first opposite portion 93b. The first extraction portion 93a and the first opposite portion 93b are placed on the same insulator layer 11. The first extraction portion 93a extends the widthwise direction of the element body 4. The first extraction portion 93a has an end portion 93c which is exposed in the side surface 4e of the element body 4 and is connected to the external electrode 5. The first opposite portion 93b extends in the longitudinal direction of the element body 4.
The opposite electrode 94 is placed at a position closer to the end surface 4b than to the end surface 4a in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4f than to the side surface 4e in the widthwise direction of the element body 4. The opposite electrodes 94 have L shapes. The opposite electrode 94 has a first extraction portion 94a and a first opposite portion 94b. The first extraction portion 94a and the first opposite portion 94b are both placed on the same insulator layer 11 as the layer on which the first opposite portion 93b of the opposite electrode 93 is placed. Namely, the first extraction portion 94a and the first opposite portion 94b are placed on the same insulator layer 11. The first extraction portion 94a extends the widthwise direction of the element body 4. The first extraction portion 94a has an end portion 94c which is exposed in the side surface 4f of the element body 4 and is connected to the external electrode 8. The first opposite portion 94b extends in the longitudinal direction of the element body 4.
The opposite electrodes 95 and 96 are placed at a position closer to the side surface 4c of the element body 4, than the coils L1 and L2, in the stack direction of the plurality of insulator layers. The opposite electrode 95 is placed at a position closer to the end surface 4a than to the end surface 4b in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4f than to the side surface 4e in the widthwise direction of the element body 4. The opposite electrodes 95 have L shape. The opposite electrode 95 has a first extraction portion 95a and a first opposite portion 95b. The first extraction portion 95a and the first opposite portion 95b are both placed on a different insulator layer 11 from the layer on which the first opposite portion 93b of the opposite electrode 93 is placed. The first extraction portion 95a and the first opposite portion 95b are placed on the same insulator layer 11. The first extraction portion 95a extends the widthwise direction of the element body 4. The first extraction portion 95a has an end portion 95c which is exposed in the side surface 4f of the element body 4 and is connected to the external electrode 6. The first opposite portion 95b extends in the longitudinal direction of the element body 4.
The opposite electrode 96 is placed at a position closer to the end surface 4b than to the end surface 4a in the longitudinal direction of the element body 4 and, also, at a position closer to the side surface 4e than to the side surface 4f in the widthwise direction of the element body 4. The opposite electrodes 96 have L shape. The opposite electrode 96 has a first extraction portion 96a and a first opposite portion 96b. The first extraction portion 96a and the first opposite portion 96b are both placed on the same insulator layer 11 as the layer on which the first opposite portion 95b of the opposite electrode 95 is placed. Namely, the first extraction portion 96a and the first opposite portion 96b are placed on the same insulator layer 11. The first extraction portion 96a extends the widthwise direction of the element body 4. The first extraction portion 96a has an end portion 96c which is exposed in the side surface 4e of the element body 4 and is connected to the external electrode 7. The first opposite portion 96b extends in the longitudinal direction of the element body 4.
The ground electrode 97 is placed at a position closer to the side surface 4d of the element body 4, than the coils L1 and L2, in the stack direction of the plurality of insulator layers. The ground electrode 97 includes a second extraction portion 97a, a second opposite portion 97b and a second opposite portion 97c. The second extraction portion 97a is placed in an insulator layer 11 between the layers on which the coils L1 and L2 are placed, and the layer on which the first opposite portion 93b of the opposite electrode 93 and the first opposite portion 94b of the opposite electrode 94 are placed. The second opposite portion 97b is placed on the same insulator layer 11 as the layer on which the first opposite portion 93b of the opposite electrode 93 is placed. The second opposite portion 97c is placed on the same insulator layer 11 as the layer on which the first opposite portion 94b of the opposite electrode 94 is placed. Namely, the second extraction portion 97a, and the second opposite portion 97b and the second opposite portion 97c are placed on the respective different insulator layers 11.
The second extraction portion 97a is placed at a substantially-center position in the widthwise direction of the element body 4 and is extended in the longitudinal direction of the element body 4. The second extraction portion 97a has an end portion 97e which is exposed in the end surface 4a of the element body 4 and is connected to the external electrode 9. The second extraction portion 97a also has an end portion 97f which is exposed in the end surface 4b of the element body 4 and is connected to the external electrode 10.
The second opposite portion 97b and the second opposite portion 97c are extended in the longitudinal direction of the element body 4 and, also, are bent to extend in the widthwise direction of the element body 4 and are connected to each other to form a connection portion 97d, at their respective ends. The connection portion 97d is electrically connected to the second extraction portion 97a via a through hole conductor 98. Namely, the second opposite portion 97b and the second opposite portion 97c are electrically connected to the second extraction portion 97a via the through hole conductor 98.
The side surface 4e (the exterior surface of the element body 4) has a region in which the first extraction portion 93a is exposed. The second opposite portion 97b is placed at a position closer to the region in which the first extraction portion 93a is exposed, than the first opposite portion 93b of the opposite electrode 93. Namely, the first opposite portion 93b is placed to be spaced apart from the side surface 4e, which is an exterior surface of the element body 4, more largely than the second opposite portion 97b. The length of the first extraction portion 93a from the side surface 4e of the element body 4 to the first opposite portion 93b is namely the distance from the portion of the opposite electrode 93 which is exposed in the side surface 4e of the element body 4 to the first opposite portion 93b. 
The side surface 4f (the exterior surface of the element body 4) has a region in which the first extraction portion 94a is exposed. The second opposite portion 97c is placed at a position closer to the region in which the first extraction portion 94a is exposed, than the first opposite portion 94b of the opposite electrode 94. Namely, the first opposite portion 94b is placed to be spaced apart from the side surface 4f, which is an exterior surface of the element body 4, more largely than the second opposite portion 97b. The length of the first extraction portion 94a from the side surface 4f of the element body 4 to the first opposite portion 94b is namely the distance from the portion of the opposite electrode 94 which is exposed in the side surface 4f of the element body 4 to the first opposite portion 94b. 
The second opposite portion 97b is placed to face the first opposite portion 93b of the opposite electrode 93, in such a way as to be spaced apart therefrom. Thus, the first discharging portion GP17 is formed between the first opposite portion 93b of the opposite electrode 93 and the second opposite portion 97b of the ground electrode 97 (see FIG. 17). The second opposite portion 97c is placed to face the first opposite portion 94b of the opposite electrode 94, in such a way as to be spaced apart therefrom. Thus, the second discharging portion GP18 is formed between the first opposite portion 94b of the opposite electrode 94 and the second opposite portion 97c of the ground electrode 97 (see FIG. 18). With this structure, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 5 and the external electrode 9, discharging is induced in the first discharging portion GP17. Similarly, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 8 and the external electrode 10, discharging is induced in the second discharging portion GP18.
The ground electrode 99 includes a second extraction portion 99a, a second opposite portion 99b and a second opposite portion 99c. The second extraction portion 99a is placed on an insulator layer 11 in the side closer to the side surface 4c of the element body 4, than the layer on which the first opposite portion 93b of the opposite electrode 93 and the first opposite portion 94b of the opposite electrode 94 are placed. The second opposite portion 99b is placed on the same insulator layer 11 as the layer on which the first opposite portion 95b of the opposite electrode 95 is placed. The second opposite portion 99c is placed on the same insulator layer 11 as the layer on which the first opposite portion 96b of the opposite electrode 96 is placed. Namely, the second extraction portion 99a, and the second opposite portion 99b and the second opposite portion 99c are placed on the respective different insulator layers 11.
The second extraction portion 99a is placed at a substantially-center position in the widthwise direction of the element body 4 and is extended in the longitudinal direction of the element body 4. The second extraction portion 99a has an end portion 99e which is exposed in the end surface 4a of the element body 4 and is connected to the esternal electrode 9. The second extraction portion 99a also has an end portion 99f which is exposed in the end surface 4b of the element body 4 and is connected to the external electrode 10.
The second opposite portion 99b and the second opposite portion 99c are extended in the longitudinal direction of the element body 4 and, also, are bent to extend in the widthwise direction of the element body 4 and are connected to each other to form a connection portion 99d, at their respective ends. The connection portion 99d is electrically connected to the second extraction portion 99a via a through hole conductor 100. Namely, the second opposite portion 99b and the second opposite portion 99c are electrically connected to the second extraction portion 99a via the through hole conductor 100.
The side surface 4f (the exterior surface of the element body 4) has a region in which the first extraction portion 95a is exposed. The second opposite portion 99b is placed at a position closer to the region in which the first extraction portion 95a is exposed, than the first opposite portion 95b of the opposite electrode 95. Namely, the first opposite portion 95b is placed to be spaced apart from the side surface 4f, which is an exterior surface of the element body 4, more largely than the second opposite portion 99b. The length of the first extraction portion 95a from the side surface 4f of the element body 4 to the first opposite portion 95b is namely the distance from the portion of the opposite electrode 95 which is exposed in the side surface 4f of the element body 4 to the first opposite portion 95b. 
The side surface 4e (the exterior surface of the element body 4) has a region in which the first extraction portion 96a is exposed. The second opposite portion 99c is placed at a position closer to the region in which the first extraction portion 96a is exposed, than the first opposite portion 96b of the opposite electrode 96. Namely, the first opposite portion 96b is placed to be spaced apart from the side surface 4e, which is an exterior surface of the element body 4, more largely than the second opposite portion 99b. The length of the first extraction portion 96a from the side surface 4e of the element body 4 to the first opposite portion 96b is namely the distance from the portion of the opposite electrode 96 which is exposed in the side surface 4e of the element body 4 to the first opposite portion 96b. 
The second opposite portion 99b is placed to face the first opposite portion 95b of the opposite electrode 95, in such a way as to be spaced apart therefrom. Thus, the third discharging portion GP19 is formed between the first opposite portion 95b of the opposite electrode 95 and the second opposite portion 99b of the ground electrode 99 (see FIG. 17). The second opposite portion 99c is placed to face the first opposite portion 96b of the opposite electrode 96, in such a way as to be spaced apart therefrom. Thus, the fourth discharging portion GP20 is formed between the first opposite portion 96b of the opposite electrode 96 and the second opposite portion 99c of the ground electrode 99 (see FIG. 18). With this structure, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 6 and the external electrode 9, discharging is induced in the third discharging portion GP19. Similarly, if a voltage with a magnitude which is equal to or more than a predetermined value is applied between the external electrode 7 and the external electrode 10, discharging is induced in the fourth discharging portion GP20.
The discharge inducing portion 101 is positioned for the first discharging portion GP17 and has the function of facilitating the occurrence of discharge in the first discharging portion GP17. The discharge inducing portion 101 connects the first opposite portion 93b of the opposite electrode 93 to the second opposite portion 97b of the ground electrode 97. The discharge inducing portion 102 is positioned for the second discharging portion GP18 and has the function of facilitating the occurrence of discharge in the second discharging portion GP18. The discharge inducing portion 102 connects the first opposite portion 94b of the opposite electrode 94 to the second opposite portion 97c of the ground electrode 97.
The discharge inducing portion 103 is positioned for the third discharging portion GP19 and has the function of facilitating the occurrence of discharge in the third discharging portion GP19. The discharge inducing portion 103 connects the first opposite portion 95b of the opposite electrode 95 to the second opposite portion 99b of the ground electrode 99. The discharge inducing portion 104 is positioned for the fourth discharging portion GP20 and has the function of facilitating the occurrence of discharge in the fourth discharging portion GP20. The discharge inducing portion 104 connects the first opposite portion 96b of the opposite electrode 96 to the second opposite portion 99c of the ground electrode 99.
The cavity portion 105 is formed for the first discharging portion GP17. The cavity portion 105 has the function of absorbing thermal expansions of the first opposite portion 93b, the second opposite portion 97b, the insulator layer 11 and the discharge inducing portion 101 during discharging. The cavity portion 106 is formed for the second discharging portion GP18. The cavity portion 106 has the function of absorbing thermal expansions of the first opposite portion 94b, the second opposite portion 97b, the insulator layer 11 and the discharge inducing portion 102 during discharging. The cavity portion 107 is formed for the third discharging portion GP19. The cavity portion 107 has the function of absorbing thermal expansions of the first opposite portion 95b, the second opposite portion 99c, the insulator layer 11 and the discharge inducing portion 103, during discharging. The cavity portion 108 is formed for the fourth discharging portion GP20. The cavity portion 108 has the function of absorbing thermal expansions of the first opposite portion 96b, the second opposite portion 99c, the insulator layer 11 and the discharge inducing portion 104, during discharging.
As described above, the ESD protection component 1E according to the present embodiment also offers the same effects as those of the aforementioned embodiments.
Although embodiments of the present invention have been described, the present invention is not limited to the aforementioned embodiments, and various changes can be made thereto within ranges which do not change the spirits defined in the respective claims.
For example, the ESD protection component 1A to 1E are not necessarily required to include the coils L1 and L2.

## Claims

1. An ESD protection component comprising:
a element body including a plurality of insulator layers are stacked;
a ground electrode placed inside the element body;
a first opposite electrode which is placed to be spaced apart from the ground electrode and forms a discharging portion in cooperation with the ground electrode;
a second opposite electrode which is placed to be spaced apart from the ground electrode and forms a discharging portion in cooperation with the ground electrode; and
a plurality of external electrodes each being provided correspondingly to a respective one of the ground electrode, the first opposite electrode and the second opposite electrode;

wherein
the ground electrode, the first opposite electrode and the second opposite electrode are each adapted to have an extraction portion connected to the corresponding external electrode out of the plurality of the external electrodes, and an opposite portion which is electrically connected to the extraction portion and forms the discharging portion,
the opposite portion of the ground electrode, the opposite portion of the first opposite electrode, and the opposite portion of the second opposite electrode are placed on the same layer, and
in at least one of the ground electrode, the first opposite electrode and the second opposite electrode, the extraction portion and the opposite portion are placed on respective different layers and also are electrically connected to each other via a through hole conductor.

2. The ESD protection component according to claim 1, wherein the extraction portion of the ground electrode and the opposite portion of the ground electrode are placed on respective different layers and also are electrically connected to each other via a through hole conductor.

3. The ESD protection component according to claim 2, wherein
the extraction portion of the first opposite electrode and the opposite portion of the first opposite electrode are placed on respective different layers and also are electrically connected to each other via a through hole conductor, and
the extraction portion of the second opposite electrode and the opposite portion of the second opposite electrode are placed on respective different layers and also are electrically connected to each other via a through hole conductor.

4. The ESD protection component according to claim 1, wherein
each of the extraction portions has an end connected to the corresponding external electrode out of the plurality of the external electrodes, the end being exposed from the element body,
the exterior surface has a first region in which the end of the extraction portion of the first opposite electrode is exposed and a second region in which the end of the extraction portion of the second opposite electrode is exposed, and
the opposite portion of the ground electrode is placed at a position closer to the first region than the opposite portion of the first opposite electrode and, also, the opposite portion of the ground electrode is placed at a position closer to the second region than the opposite portion of the second opposite electrode.