JP2014082001A - Esd protection device and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ESD protection device including a pair of discharge electrode layers facing each other at a narrow interval, and having a small discharge start voltage, and to provide a manufacturing method of the same.SOLUTION: An ESD protection device 100 includes a ceramic element assembly 6, a discharge auxiliary electrode layer 3 formed therein, a first discharge electrode layer 2 formed on one principal surface of the discharge auxiliary electrode layer 3, a second discharge electrode layer 4 formed on the other principal surface of the discharge auxiliary electrode layer 3, and a plurality of external electrodes 12, 12 formed on a surface of the ceramic element assembly 6 and connected electrically with the first discharge electrode layer 2 or the second discharge electrode layer 4. The end faces 3a, 2a, 4a of the discharge auxiliary electrode layer 3, the first discharge electrode layer 2 and the second discharge electrode layer 4 are exposed to the surface D of the ceramic element assembly 6, and a protective film 11 is formed on the surface D of the ceramic element assembly 6 so as to cover the end faces 3a, 2a, 4a.

Description

  The present invention relates to an ESD protection device and a manufacturing method thereof.

  Conventionally, in order to protect semiconductor devices and electronic circuits from static electricity, for example, an ESD (Electro-Static Discharge) protection device as shown in Patent Document 1 (WO2008 / 146514) has been used.

  FIG. 13 is a cross-sectional view of the ESD protection device 400 disclosed in Patent Document 1.

  The ESD protection device 400 includes a ceramic body 106 having a cavity 107 therein.

  A pair of discharge electrode layers 102 and 104 are formed in the cavity 107 so that the end faces 102a and 104a face each other with a gap G therebetween.

  Under the discharge electrode layers 102 and 104 and the region 109 facing the discharge electrode layers 102 and 104, a discharge auxiliary electrode layer 103 is formed. The discharge auxiliary electrode layer 103 includes conductive particles and an insulator material.

  On the surface of the ceramic body 106, a plurality of external electrodes 112, 112 electrically connected to any one of the discharge electrode layers 102, 104 are formed.

  The discharge start voltage of the ESD protection device 400 can be lowered by reducing the gap G between the end faces 102a, 104a of the discharge electrode layers 102, 104.

WO2008 / 146514

  In the conventional method of manufacturing the ESD protection device 400, the pair of discharge electrode layers 102 and 104, whose end faces 102a and 104a face each other with a gap G, are formed by screen printing, for example.

  However, since the printing position accuracy is not high in screen printing, a pair of discharge electrode layers 102 and 104 are formed so that the end faces 102a and 104a face each other with a narrow gap G, and an ESD protection device with a low discharge start voltage is obtained. It was difficult.

  An object of the present invention is to provide an ESD protection device having a small discharge start voltage, which includes a pair of discharge electrode layers facing each other at a narrow interval, and a manufacturing method thereof.

  In order to achieve the above object, an ESD protection device of the present invention includes a ceramic body, a discharge auxiliary electrode layer formed inside the ceramic body and including conductive particles and an insulator material, and a discharge auxiliary electrode layer. A first discharge electrode layer formed on one main surface; a second discharge electrode layer formed on the other main surface of the discharge auxiliary electrode layer; and a first body formed on the surface of the ceramic body. A plurality of external electrodes electrically connected to the discharge electrode layer or the second discharge electrode layer, and the end surfaces of the discharge auxiliary electrode layer, the first discharge electrode layer, and the second discharge electrode layer are ceramic bodies A protective film is formed on the surface of the ceramic body so as to cover the exposed end faces of the discharge auxiliary electrode layer, the first discharge electrode layer, and the second discharge electrode layer. It is characterized by.

  The ESD protection device manufacturing method of the present invention includes a step of forming a first ceramic green sheet, a step of forming a second ceramic green sheet, and one main surface of the first ceramic green sheet. A step of forming an unfired first discharge electrode layer by applying a discharge electrode layer forming paste, and a discharge auxiliary electrode layer forming process including conductive particles and an insulator material on the first discharge electrode layer A step of forming an unfired auxiliary discharge electrode layer by applying a paste, and an unfired second discharge electrode layer is formed by applying a discharge electrode layer forming paste on the auxiliary discharge electrode layer A step of forming a laminated body by laminating a second ceramic green sheet on one main surface of the first ceramic green sheet and pressing the first ceramic green sheet, and a first discharge The step of dividing the laminate, the step of firing the laminate, the first discharge electrode layer, and the discharge auxiliary electrode, with the plane including the cross section of the polar layer, the discharge auxiliary electrode layer, and the second discharge electrode layer as the division plane A step of forming a protective film on the surface of the laminate so as to cover the dividing surface of the layer and the second discharge electrode layer, and a first discharge electrode layer or a second layer on the surface of the divided laminate And a step of forming a plurality of external electrodes electrically connected to the discharge electrode layer.

  Alternatively, the ESD protection device manufacturing method of the present invention includes a step of forming a first ceramic green sheet, a step of forming a second ceramic green sheet, and one main surface of the first ceramic green sheet. A step of forming an unfired first discharge electrode layer by applying a discharge electrode layer forming paste, and a discharge auxiliary electrode layer forming process including conductive particles and an insulator material on the first discharge electrode layer A step of forming an unfired auxiliary discharge electrode layer by applying a paste, and an unfired second discharge electrode layer is formed by applying a discharge electrode layer forming paste on the auxiliary discharge electrode layer A step of forming a laminated body by laminating a second ceramic green sheet on one main surface of the first ceramic green sheet and pressing the second ceramic green sheet; A step of forming a cavity penetrating through the ceramic green sheet, the first discharge electrode layer, the discharge auxiliary electrode layer, the second discharge electrode layer, and the first ceramic green sheet in order, and a plane including a cross section of the cavity as a dividing plane The step of dividing the laminate, the step of firing the laminate, and the ceramic body so as to cover the end faces exposed in the cavities of the first discharge electrode layer, the discharge auxiliary electrode layer, and the second discharge electrode layer Forming a protective film on the surface; forming a plurality of external electrodes electrically connected to the first discharge electrode layer or the second discharge electrode layer on the surface of the divided laminate; It is characterized by providing.

  ADVANTAGE OF THE INVENTION According to this invention, the ESD protection device with a small discharge start voltage provided with a pair of discharge electrode layer which opposes at a narrow space | interval can be obtained.

FIG. 1A is a perspective view of an ESD protection device 100 according to the first embodiment of the present invention. FIG. 1B is a perspective view of a main part of the ESD protection device 100, and the protective film 11 and the external electrodes 12 and 12 in FIG. 1A are omitted. FIG. 1C is a cross-sectional view of the ESD protection device 100, which is taken along the line AA in FIG. FIG. 2 is a perspective view showing steps applied in the method of manufacturing the ESD protection device 100 according to the first embodiment of the present invention. FIG. 3 is a continuation of FIG. 2 and is a perspective view showing steps applied in the method of manufacturing the ESD protection device 100 according to the first embodiment of the present invention. FIG. 4 is a continuation of FIG. 3 and is a perspective view showing steps applied in the method of manufacturing the ESD protection device 100 according to the first embodiment of the present invention. FIG. 5 is a continuation of FIG. 4 and is a perspective view of relevant parts showing steps applied in the method of manufacturing the ESD protection device 100 according to the first embodiment of the present invention. FIG. 6A is a continuation of FIG. 5, and is a main part see-through portion showing steps applied in the method of manufacturing the ESD protection device 100 according to the first embodiment of the present invention. FIG. 6B is a side view of the ESD protection device 100, and the stacked body 10 in FIG. 6A is viewed from the dividing plane D side. FIG. 7 is a continuation of FIG. 6 and is a perspective view showing steps applied in the method of manufacturing the ESD protection device 100 according to the first embodiment of the present invention. FIG. 8 is a plan view showing the laminate 10 in FIG. 5 in a parent substrate state. The second ceramic green sheet 5a is omitted. FIG. 9 is a perspective view of an ESD protection device 200 according to the second embodiment of the present invention. FIG. 10 is a plan view showing steps applied in the method for manufacturing the ESD protection device 200 according to the second embodiment of the present invention. The second ceramic green sheet 5a is omitted. FIG. 11 is a continuation of FIG. 10 and is a perspective view showing steps applied in the method of manufacturing the ESD protection device 200 according to the second embodiment of the present invention. FIG. 12 is a cross-sectional view of an ESD protection device 300 according to the third embodiment of the present invention. FIG. 13 is a cross-sectional view of a conventional ESD protection device 400.

Below, the form for implementing this invention is demonstrated with drawing.
(First embodiment)
1A to 1C show an ESD protection device 100 according to a first embodiment of the present invention.

  As shown in FIG. 1 (A), the ESD protection device 100 includes a ceramic body 6 in which a first ceramic green sheet 1 and second ceramic green sheets 5a and 5b are laminated and press-bonded together. Yes. As the material of the ceramic body 6, for example, a BAS material obtained by mixing each material mainly including Ba, Al, and Si is used.

  As shown in FIG. 1B, the ESD protection device 100 is formed so that the discharge auxiliary electrode layer 3 extends from the inside of the ceramic body 6 to the end face D of the ceramic body 6. The discharge auxiliary electrode layer 3 includes conductor particles such as alumina-coated Cu particles, and an insulator material made of a BAS material or the like.

  A first discharge electrode layer 2 made of Cu or the like is formed on one main surface of the discharge auxiliary electrode layer 3.

  A second discharge electrode layer 4 made of Cu or the like is formed on the other main surface of the discharge auxiliary electrode layer 3.

  End surfaces 3 a, 2 a, 4 a of the discharge auxiliary electrode layer 3, the first discharge electrode layer 2, and the second discharge electrode layer 4 are exposed at the surface D of the ceramic body 6.

  On the surface D of the ceramic body 6 so as to cover the end faces 3a, 2a and 4a of the discharge auxiliary electrode layer 3, the first discharge electrode layer 2 and the second discharge electrode layer 4, respectively, FIG. , (C), a protective film 11 is formed. For example, silicone resin or epoxy resin is used as the material of the protective film 11.

  On the surface of the ceramic body 6, as shown in FIG. 1A, a plurality of external electrodes 12 are connected so as to be electrically connected to the first discharge electrode layer 2 or the second discharge electrode layer 4. , 12 are formed.

  In the ESD protection device 100 described above, as shown in FIG. 1 (C), the end surfaces 2a and 4a of the first discharge electrode layer 2 and the second discharge electrode layer 4 have the discharge auxiliary electrode layer at the shortest distance. 3 with a gap G corresponding to the thickness of 3. As will be described later, in the method for manufacturing the ESD protection device 100 of the present invention, since the discharge auxiliary electrode layer 3 can be formed with a small thickness, the interval G can be set small.

  The ESD protection device 100 operates when a creeping discharge or an air discharge occurs between the end faces 2a and 4a of the first discharge electrode layer 2 and the second discharge electrode layer 4, respectively. Since the pair of discharge electrode layers 2 and 4 facing each other with a narrow gap G are provided, the discharge start voltage can be reduced.

  Table 1 shows the discharge start voltage values of the conventional ESD protection device 400 shown in FIG. 13 and two types of ESD protection devices 100 (Examples 1 and 2) according to the first embodiment of the present invention having different intervals G. Indicates. In Example 1, the gap G between the first discharge electrode layer 2 and the second discharge electrode layer 4 is 20 μm, and Example 2 is 10 μm. The interval G in the conventional ESD protection device 400 is 30 μm.

  The discharge start voltage value is measured by applying ESD from a low voltage by contact discharge according to the IEC standard (IEC61000-4-2). When the ESD protection devices 100 and 400 are operated, a circle is indicated, and when the ESD protection devices 100 and 400 are not operated, an x is indicated.

  As can be seen from Table 1, the ESD protection device 100 according to the first embodiment of the present invention operates at a lower voltage than the conventional ESD protection device 400.

  Hereinafter, a manufacturing method of the ESD protection device 100 according to the first embodiment of the present invention will be described with reference to FIGS.

  First, each material mainly composed of Ba, Al, and Si is prepared and mixed at a predetermined ratio, and calcined at 800 to 1000 ° C. to form a BAS material. The obtained BAS material is pulverized with a zirconia ball mill for 12 hours to form an insulator material made of a BAS material having an average particle diameter of about 1 μm. An organic solvent such as toluene or echinene is added to the insulator material and mixed. Thereafter, a binder and a plasticizer are added and mixed to form a slurry.

  Next, the slurry is formed by a doctor blade method to form a first ceramic green sheet and a second ceramic green sheet having a thickness of 50 μm.

  Next, a solvent is added to a binder resin composed of Cu powder having an average particle diameter of about 2 μm and ethyl cellulose, and the mixture is stirred and mixed with three rolls to form a discharge electrode layer forming paste.

  Next, as shown in FIG. 2, the unfired first discharge electrode layer 2 is formed by applying a discharge electrode layer forming paste on one main surface of the first ceramic green sheet 1 by screen printing. Form. The thickness of the first discharge electrode layer 2 is, for example, 10 μm.

  Next, a discharge auxiliary electrode layer forming paste containing conductive particles and an insulator material is formed. Specifically, an alumina-coated Cu particle having an average particle size of about 2 μm and an insulating material made of a BAS material having an average particle size of about 1 μm used when forming the slurry described above are prepared at a predetermined ratio, and a binder resin is prepared. And a solvent are added, and the paste for forming a discharge auxiliary electrode layer is formed by stirring and mixing with three rolls.

  Next, as shown in FIG. 3, an unfired auxiliary discharge electrode layer 3 is formed on the first discharge electrode layer 2 by applying a discharge auxiliary electrode layer forming paste by screen printing. The thickness of the auxiliary discharge electrode layer 3 can be set as small as 10 μm or 20 μm, for example.

  Next, as shown in FIG. 4, a discharge electrode layer forming paste is applied on the discharge auxiliary electrode layer 3 by screen printing to form an unfired second discharge electrode layer 4. The thickness of the second discharge electrode layer 4 is, for example, 10 μm.

  Next, as shown in FIG. 5, a plurality of second ceramic green sheets 5a (a plurality of second ceramic green sheets 5a are shown as an integral unit) are laminated on the upper surface of the first ceramic green sheet 1. Crimp.

  Next, a plurality of second ceramic green sheets 5b (a plurality of second ceramic green sheets 5b are shown as an integral unit) are laminated on the lower surface of the first ceramic green sheet 1, and the thickness is reduced by pressure bonding. A laminate 10 having a thickness of 0.3 mm is formed.

  Next, as shown in FIG. 6A, a micro cutter was used with the plane including the cross sections of the first discharge electrode layer 2, the discharge auxiliary electrode layer 3 and the second discharge electrode layer 4 as the dividing plane D. The laminated body 10 is divided by cutting. The size of the divided laminate 10 is, for example, 1.0 mm × 0.5 mm × 0.3 mm. On the dividing surface D, as shown in FIG. 6B, the end surfaces 2a and 4a of the first discharge electrode layer 2 and the second discharge electrode layer 4 that face each other with a gap G through the auxiliary discharge electrode layer 3 are provided. Is exposed.

Next, the divided laminate 10 is fired in an N ₂ atmosphere.

  Next, as shown in FIG. 7, a plurality of conductive layers electrically connected to the first discharge electrode layer 2 or the second discharge electrode layer 4 by applying and baking a conductive paste on the surface of the laminate 10. External electrodes 12 and 12 are formed.

  Next, a silicone resin is applied on the dividing surface D of the laminate 10 so as to cover the end surfaces 3a, 2a, 4a of the first discharge electrode layer 2, the discharge auxiliary electrode layer 3, and the second discharge electrode layer 4, respectively. Apply.

  Next, an epoxy resin is formed on the silicone resin to complete the protective film 11 having a laminated structure of the silicone resin and the epoxy resin as shown in FIG.

  Finally, the ESD protection device 100 is completed by forming a film made of Ni and Sn on the external electrodes 12 and 12 by electrolytic plating.

  In the manufacturing method of the ESD protection device 100 shown above, since the printing thickness accuracy of screen printing is high, a narrow gap G of, for example, 10 μm or 20 μm can be formed.

  In the manufacturing method described above, mass productivity can be improved by forming the laminated body 10 in a parent substrate state and dividing the laminated body 10.

  Specifically, first, similarly to the manufacturing method described above, the laminate 10 in the parent substrate state having the pattern of the first discharge electrode layer 2, the discharge auxiliary electrode layer 3, and the second discharge electrode layer 4 is illustrated. As shown in FIG.

  Next, the first discharge electrode layer 2, the discharge auxiliary electrode layer 3, and the second discharge electrode layer 4 are laminated by cutting along the cut line CL so that the plane including the cross section becomes the dividing plane D. Divide the body 10.

As described above, according to the present invention, the first discharge electrode layer 2 and the second discharge electrode facing each other with a narrow gap G through the auxiliary discharge electrode layer 3 by a low cost method of screen printing and cutting. Layer 4 can be formed.
(Second Embodiment)
FIG. 9 shows an ESD protection device 200 according to the second embodiment of the present invention.

  In the ESD protection device 100 according to the first embodiment shown in FIG. 1, the surface D of the ceramic body 6 is flat. However, in the ESD protection device 200, as shown in FIG. The surface D is provided with a concave surface 8. On the concave surface 8, end surfaces 3 a, 2 a, 4 a of the discharge auxiliary electrode layer 3, the first discharge electrode layer 2, and the second discharge electrode layer 4 are exposed. A protective film 11 is formed in a space surrounded by the concave surface 8. Other configurations of the ESD protection device 200 are the same as those of the ESD protection device 100.

  In the ESD protection device 200 according to the second embodiment, since the protection film 11 is formed in the space surrounded by the concave surface 8, the protection film 11 is difficult to protrude outside the ceramic body 6, and the ESD protection device. The overall size of 200 can be reduced.

  Hereinafter, a method for manufacturing the ESD protection device 200 according to the second embodiment of the present invention will be described with reference to FIGS. 9 to 11.

  First, similarly to the first embodiment, the laminate 10 shown in FIGS. 5 and 8 is formed.

  Next, unlike the first embodiment, as shown in FIG. 10, the second ceramic green sheet 5a, the first discharge electrode layer 2, the discharge auxiliary electrode layer 3, the second discharge electrode layer are formed by mechanical punching or the like. 4. A cavity 7 that penetrates the first ceramic green sheet 5b in order is formed.

  Next, unlike the first embodiment, as illustrated in FIG. 10, the stacked body 10 is divided along the cut line CL so that the surface including the cross section of the cavity 7 becomes the dividing surface D. As a result, as shown in FIG. 11, the divided laminated body 10 has a concave surface 8 on the division surface D of the ceramic body 6.

Next, as in the first embodiment, the divided laminate 10 is fired in an N ₂ atmosphere.

  Next, as shown in FIG. 11, a plurality of external electrodes 12, 12 are formed on the surface of the multilayer body 10 as in the first embodiment.

  Next, unlike the first embodiment, as shown in FIG. 9, end faces 2a and 3a exposed in the cavity 7 of the first discharge electrode layer 2, the discharge auxiliary electrode layer 3 and the second discharge electrode layer 4 are formed. 4a, a protective film 11 is formed on the surface of the laminate 10 so as to cover 4a.

Finally, as in the first embodiment, the ESD protection device 200 is completed by forming a film made of Ni and Sn on the external electrodes 12 and 12 by electrolytic plating.
(Third embodiment)
FIG. 12 shows an ESD protection device 300 according to the third embodiment of the present invention.

  In the ESD protection devices 100 and 200 according to the first and second embodiments shown in FIGS. 1 and 9, each of the discharge auxiliary electrode layer 3, the first discharge electrode layer 2, and the second discharge electrode layer 4 is provided. The end faces 3a, 2a, 4a were exposed on the same surface D of the ceramic body 6, but in the ESD protection device 300 according to the third embodiment, the first discharge electrode layer 2, the second discharge electrode The end surfaces 2 a and 4 a of each layer 4 protrude from the end surface 3 a of the auxiliary discharge electrode layer 3 toward the outside of the ceramic body 6. Other configurations of the ESD protection device 300 are the same as those of the ESD protection device 100.

  In the ESD protection device 300 according to the third embodiment, not only the end surfaces 2a and 4a of the first discharge electrode layer 2 and the second discharge electrode layer 4, but also the first discharge electrode layer 2 and the second discharge The main surfaces 2b and 4b of the electrode layer 4 are opposed to each other. Therefore, compared with the ESD protection device 100 according to the first embodiment and the ESD protection device 200 according to the second embodiment, the ESD protection device 300 includes the first discharge electrode layer 2 and the second discharge electrode layer 4. Since the opposing area of the electrode becomes large, the repeated discharge resistance (continuous operability) can be improved.

  Hereinafter, a method for manufacturing the ESD protection device 300 according to the third embodiment of the present invention will be described.

  Unlike the first and second embodiments of the present invention, in the third embodiment, a discharge auxiliary electrode layer forming paste and a discharge electrode layer forming paste having different shrinkage rates after firing are used. Specifically, the shrinkage rate after firing of the discharge auxiliary electrode layer 3 is 85%, and the shrinkage rates after firing of the first discharge electrode layer 2 and the second discharge electrode layer 4 are 86 to 90%. The composition of the discharge auxiliary electrode layer forming paste and the discharge electrode layer forming paste is adjusted.

  In the discharge auxiliary electrode layer forming paste, an insulator material made of alumina-coated Cu particles and a BAS material is mixed at a ratio of 80 wt%, and a binder resin and a solvent are mixed at a ratio of 20 wt%.

  In the discharge electrode layer forming paste, alumina powder is newly added to the first embodiment, and Cu particles and alumina powder are mixed at a ratio of 80 wt%, and a binder resin and a solvent are mixed at a ratio of 20 wt%. Cu particles and alumina powder are mixed at a ratio of 95 vol% and 5 vol%.

  By setting the shrinkage rate after firing as described above, in the step of firing the laminate 10, the first discharge electrode layer 2 and the second discharge electrode layer 4 become the discharge auxiliary electrode layer 3 due to the difference in shrinkage rate. Projecting toward the outside of the ceramic body 6.

  The ESD protection device and the manufacturing method thereof according to the embodiment of the present invention are not limited to the contents described above, and various changes can be made in accordance with the spirit of the invention.

  For example, in the above embodiment, Cu is used as the material of the conductor particles contained in the discharge electrode layer forming paste, but Ag, Pd, Pt, Al, Ni, W, or a combination thereof may be used.

In addition, the material used for the ceramic body 6 is a BAS material obtained by mixing each material mainly including Ba, Al, and Si. However, a glass material added to foresterite or a glass material added to CrZrO ₃ is used. You may use what added.

  Further, although the BAS material is used as the insulator material included in the discharge auxiliary electrode layer forming paste, a ceramic material such as alumina, silica, zirconia, or the like may be used.

  In the method for manufacturing the ESD protection device 300 according to the third embodiment, the composition and mixing ratio of the discharge auxiliary electrode layer forming paste and the discharge electrode layer forming paste are not limited to those described above, and As long as the shrinkage rate after firing of the electrode layer forming paste is set smaller than that of the discharge electrode layer forming paste, any content may be used.

Moreover, although the laminated body 10 is fired in an N ₂ atmosphere, it may be fired in a rare gas atmosphere such as Ar or Ne. Further, when the first discharge electrode layer 2, the second discharge electrode layer 4 and the discharge auxiliary electrode layer 3 are made of a material that does not oxidize, they may be fired in an air atmosphere.

Further, after cutting the laminated body 10, although fired in N ₂ atmosphere, it was fired in N ₂ atmosphere, may be cut laminate 10.

DESCRIPTION OF SYMBOLS 1 1st ceramic green sheet 2 1st discharge electrode layer 2a End surface 2b of 1st discharge electrode layer Main surface 3 of 1st discharge electrode layer 3 Discharge auxiliary electrode layer 3a End surface 4 of 2nd discharge auxiliary electrode layer 2nd discharge Electrode layer 4a End surface 4b of second discharge electrode layer Main surfaces 5a and 5b of second discharge electrode layer Second ceramic green sheet 6 Ceramic body 7 Cavity 8 Concave surface 10 Laminate 11 Protective film 12 External electrodes 100, 200 , 300 ESD protection device G Interval D Surface, split surface CL Cut line

Claims (5)

A ceramic body,
A discharge auxiliary electrode layer formed inside the ceramic body and including conductive particles and an insulator material;
A first discharge electrode layer formed on one main surface of the discharge auxiliary electrode layer;
A second discharge electrode layer formed on the other main surface of the discharge auxiliary electrode layer;
A plurality of external electrodes formed on the surface of the ceramic body and electrically connected to the first discharge electrode layer or the second discharge electrode layer;
End surfaces of the discharge auxiliary electrode layer, the first discharge electrode layer, and the second discharge electrode layer are exposed on the surface of the ceramic body,
A protective film is formed on the surface of the ceramic body so as to cover the exposed end surfaces of the discharge auxiliary electrode layer, the first discharge electrode layer, and the second discharge electrode layer. ESD protection device. Provided with a concave surface on the surface of the ceramic body,
2. The ESD protection device according to claim 1, wherein end surfaces of the discharge auxiliary electrode layer, the first discharge electrode layer, and the second discharge electrode layer are exposed on the concave surface.   The end surfaces of the first discharge electrode layer and the second discharge electrode layer protrude beyond the end surface of the discharge auxiliary electrode layer toward the outside of the ceramic body. ESD protection device described in 1. Forming a first ceramic green sheet;
Forming a second ceramic green sheet;
A step of forming an unfired first discharge electrode layer by applying a discharge electrode layer forming paste on one main surface of the first ceramic green sheet;
A step of forming an unfired discharge auxiliary electrode layer by applying a paste for forming a discharge auxiliary electrode layer containing conductive particles and an insulator material on the first discharge electrode layer;
Forming an unfired second discharge electrode layer by applying a discharge electrode layer forming paste on the discharge auxiliary electrode layer; and
Forming the laminate by laminating the second ceramic green sheet on the one main surface of the first ceramic green sheet and press-bonding;
Dividing the laminate with a plane including a cross section of the first discharge electrode layer, the discharge auxiliary electrode layer, and the second discharge electrode layer as a division plane;
Firing the laminate;
Forming a protective film on the surface of the laminate so as to cover the divided surfaces of the first discharge electrode layer, the discharge auxiliary electrode layer, and the second discharge electrode layer;
Forming a plurality of external electrodes electrically connected to the first discharge electrode layer or the second discharge electrode layer on the surface of the divided laminate;
A method of manufacturing an ESD protection device, comprising: Forming a first ceramic green sheet;
Forming a second ceramic green sheet;
A step of forming an unfired first discharge electrode layer by applying a discharge electrode layer forming paste on one main surface of the first ceramic green sheet;
A step of forming an unfired discharge auxiliary electrode layer by applying a paste for forming a discharge auxiliary electrode layer containing conductive particles and an insulator material on the first discharge electrode layer;
Forming an unfired second discharge electrode layer by applying a discharge electrode layer forming paste on the discharge auxiliary electrode layer; and
Forming the laminate by laminating the second ceramic green sheet on the one main surface of the first ceramic green sheet and press-bonding;
Forming a cavity that sequentially penetrates the second ceramic green sheet, the first discharge electrode layer, the discharge auxiliary electrode layer, the second discharge electrode layer, and the first ceramic green sheet;
Dividing the laminate with a plane including a cross section of the cavity as a dividing plane;
Firing the laminate;
Forming a protective film on the surface of the ceramic body so as to cover the end surfaces exposed in the cavities of the first discharge electrode layer, the discharge auxiliary electrode layer, and the second discharge electrode layer;
Forming a plurality of external electrodes electrically connected to the first discharge electrode layer or the second discharge electrode layer on the surface of the divided laminate;
A method of manufacturing an ESD protection device, comprising:

Images