JP6048577B2 - ESD protection device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an ESD protection device in which first and second discharge electrodes are opposed to each other in an insulator, and a method for manufacturing the ESD protection device.

  2. Description of the Related Art Conventionally, ESD protection devices are widely used to protect electronic devices from ESD (Electro-Static-Discharge), that is, electrostatic discharge.

  For example, in the ESD protection device described in Patent Document 1 below, the first discharge electrode and the second discharge electrode are partially opposed in the height direction of the ceramic body. This facing portion is exposed in the cavity of the ceramic body. The cavity is formed by using resin beads that disappear upon firing. That is, resin beads are arranged in the cavity forming portion before firing the ceramic body. The resin beads are lost by firing. Thereby, a cavity is formed.

  On the other hand, Patent Document 2 below discloses an ESD protection device in which a cavity is provided at a certain height position of an insulating substrate. Here, the tip of the first discharge electrode and the tip of the second discharge electrode face each other at a certain height position in the insulating substrate. This opposing part is located in the cavity. A powdery auxiliary electrode material is dispersed in the cavity. The auxiliary electrode material is made of a conductive powder.

WO2009 / 069270 A1 WO2010 / 061550 A1

  The inventor of the present application has made the following study in order to lower the discharge start voltage in the ESD protection apparatus. In the ESD protection device described in Patent Document 1, it is difficult to further lower the discharge start voltage.

  On the other hand, in order to lower the discharge start voltage, it is desirable that a large number of air discharge paths and creeping discharge paths exist with a narrow gap. In the ESD protection device described in Patent Document 2, this discharge gap is formed by a printing method. However, it has been difficult to form a narrow gap with high accuracy by such a printing method. For this reason, it is difficult to lower the discharge start voltage.

  Note that a narrow gap can be formed with high accuracy by using a photolithography etching method, a laser trimming method, or the like. However, there is a problem that the manufacturing cost is significantly increased.

  An object of the present invention is to provide an ESD protection device and a method for manufacturing the same that can effectively lower a discharge start voltage without causing an increase in cost.

  The ESD protection device of the present invention includes an insulator, first and second discharge electrodes, and a discharge gap forming layer.

  The first and second discharge electrodes are opposed to each other in the insulator. The discharge gap forming layer is a portion sandwiched between the first discharge electrode and the second discharge electrode in a portion where the first and second discharge electrodes face each other. The discharge gap formation layer has a plurality of cavities that are continuous with the first discharge electrode and the second discharge electrode.

  In the ESD protection apparatus according to the present invention, preferably, the insulator is a laminated insulating substrate having an upper surface and a lower surface, and the first and second discharge electrodes are in the height direction of the insulating substrate. Are separated from each other.

  In the ESD protection apparatus according to the present invention, preferably, an auxiliary electrode is provided on the discharge gap forming layer. The auxiliary electrode may contain semiconductor ceramic particles. The auxiliary electrode may include conductive particles coated with an insulating material.

  In the present invention, the discharge gap forming layer may include a high dielectric constant material having a dielectric constant higher than that of the insulating material constituting the insulator.

  The manufacturing method of the ESD protection apparatus according to the present invention includes the following steps.

  Applying a first discharge electrode paste on the first insulator layer;

  A step of applying a discharge gap forming layer paste containing a solid that disappears upon firing to a part of the first discharge electrode paste.

  Applying a second discharge electrode paste so as to face the first discharge electrode paste through at least part of the discharge gap forming layer paste;

  Forming a second insulator layer so as to cover the second discharge electrode paste;

  The first and second insulator layers are baked to form an insulator, and the first discharge electrode paste, the discharge gap forming layer paste, and the second discharge electrode paste are baked to form a first , A second discharge electrode, and a discharge gap forming layer provided between the first and second discharge electrodes and having a plurality of cavities connected to the first discharge electrode and the second discharge electrode. Firing step.

  In the manufacturing method of the ESD protection apparatus according to the present invention, preferably, a resin is used as a solid that disappears by firing, and more preferably, resin beads are used.

  In the method for manufacturing an ESD protection device according to the present invention, it is preferable that the discharge gap forming layer paste contains an auxiliary electrode material. As such an auxiliary electrode material, semiconductor ceramic particles are preferably used. The auxiliary electrode material may contain conductive particles coated with an insulating material.

  In the ESD protection device manufacturing method of the present invention, the discharge gap forming layer paste may include a high dielectric constant material having a dielectric constant higher than that of the material constituting the insulator.

  According to the ESD protection device and the manufacturing method thereof according to the present invention, the discharge gap forming layer has a plurality of cavities that are continuous with the first discharge electrode and the second discharge electrode. Can be lowered. In addition, since it is not necessary to use a printing method to reduce the discharge gap, it is difficult to increase the cost of the ESD protection device.

FIG. 1 is a front sectional view of an ESD protection apparatus according to an embodiment of the present invention. FIG. 2 is a schematic plan view for explaining the positional relationship among the first discharge electrode, the second discharge electrode, and the discharge gap forming layer in the embodiment of the present invention. FIG. 3A to FIG. 3C are each a partially cutaway enlarged front sectional view for explaining a method for manufacturing an ESD protection device according to an embodiment of the present invention. FIG. 4 is a front sectional view of an ESD protection device according to a modification of the embodiment shown in FIG. FIG. 5 is a partially cutaway enlarged front sectional view for explaining the structure of the discharge gap forming layer in the ESD protection apparatus according to the modification of the embodiment of the present invention. FIG. 6 is a partially cutaway enlarged front sectional view for explaining the structure of the discharge gap forming layer in the ESD protection apparatus according to another modification of the embodiment of the present invention. FIG. 7A to FIG. 7C are each a partially cutaway enlarged front sectional view for explaining a method of manufacturing an ESD protection device according to still another modified example of the present invention. FIG. 8 is a schematic partial cutaway front sectional view showing a state in which the first discharge electrode paste, the discharge gap forming layer paste, and the second discharge electrode paste are printed in the manufacturing method of one embodiment of the present invention. is there. FIG. 9 is a schematic plan view showing a modification of the method of laminating the first discharge electrode paste, the discharge gap forming layer paste, and the second discharge electrode paste. FIG. 10 is a schematic plan view showing another modification of the method of laminating the first discharge electrode paste, the discharge gap forming layer paste, and the second discharge electrode paste.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1 is a front sectional view of an ESD protection apparatus according to an embodiment of the present invention.

  The ESD protection device 1 has an insulator made of a laminated insulating substrate 2. The insulator is not limited to the laminated insulating substrate 2.

  The laminated insulating substrate 2 is made of insulating ceramics except for a later-described discharge gap forming layer. Although it does not specifically limit as insulating ceramics, In this embodiment, what is called a BAS material is used. The BAS material is a ceramic having a ceramic composition mainly composed of Ba, Al, and Si.

  The insulating substrate 2 is formed by laminating and firing a plurality of ceramic green sheets made of the BAS material. The insulating substrate 2 has an upper surface 2a, a lower surface 2b, and end surfaces 2c and 2d. The insulating substrate 2 has a pair of side surfaces (not shown). In the present embodiment, the insulating substrate 2 has a rectangular plate shape. However, the shape of the insulating substrate 2 is not particularly limited. The insulating substrate 2 is not limited to ceramics but may be made of a resin or the like.

  A first discharge electrode 3 and a second discharge electrode 4 are disposed in the insulating substrate 2. The first discharge electrode 3 extends parallel to the upper surface 2a and the lower surface 2b of the insulating substrate 2 and is drawn out to the end surface 2c. The second discharge electrode 4 is provided above the first discharge electrode 3. The second discharge electrode 4 is drawn out to the end face 2d.

  The first discharge electrode 3 and the second discharge electrode 4 partially face each other in the height direction of the insulating substrate 2.

  The first discharge electrode 3 and the second discharge electrode 4 can be formed of an appropriate conductive material. In the present embodiment, the first and second discharge electrodes 3 and 4 are made of Cu. However, Ag, Pd, Pt, Al, Ni, W, or an alloy mainly composed of these may be used.

  In the portion where the first discharge electrode 3 and the second discharge electrode 4 face each other, the portion sandwiched between the first discharge electrode 3 and the second discharge electrode 4 is the discharge gap forming layer 5. is there.

  The discharge gap forming layer 5 has a plurality of cavities 5a. The cavity 5a is surrounded by the columnar portion 5b. The plurality of cavities 5 a are connected to the first discharge electrode 3 and the second discharge electrode 4. That is, in the insulating substrate 2, the cavity 5 a is connected to the second discharge electrode 4 at the upper end and is connected to the first discharge electrode 3 at the lower end. Part of the first discharge electrode 3 and the second discharge electrode 4 is exposed in the cavity 5a.

  When static electricity is applied, a discharge occurs between the first discharge electrode 3 and the second discharge electrode 4 in the cavity 5a. This discharge is generated by both the air discharge path and the creeping discharge path. In the present embodiment, since a plurality of cavities 5a are provided, not only the air discharge path but also a number of creeping discharge paths exist.

  The discharge start voltage in the ESD protection apparatus can be lowered as the air discharge path and the creeping discharge path increase. In the present embodiment, since the plurality of cavities 5a are provided, a large number of air discharge paths and a large number of creeping discharge paths are formed. Therefore, it is possible to effectively reduce the discharge start voltage.

  The discharge gap forming layer 5 is a layer for forming the plurality of cavities 5a, and is formed at a portion where the first discharge electrode 3 and the second discharge electrode 4 face each other in the height direction. positioned. However, the discharge gap formation layer 5 may protrude outward in the lateral direction on the drawing from the portion where the first discharge electrode 3 and the second discharge electrode 4 overlap in the height direction. The planar shape of the discharge gap forming layer 5 will be described in more detail later with reference to a modification described later.

  As shown in FIG. 1, external electrodes 6 and 7 are formed on the end faces 2c and 2d so as to be electrically connected to the first and second discharge electrodes 3 and 4, respectively. The external electrodes 6 and 7 can be formed of an appropriate metal material such as Cu, Al, Ag, or Pd.

  In the ESD protection device 1, when static electricity is applied between the external electrodes 6 and 7, a discharge occurs between the first discharge electrode 3 and the second discharge electrode 4. As described above, since the plurality of cavities 5a are provided, the discharge start voltage can be effectively reduced.

  Next, the manufacturing method of the ESD protection apparatus 1 will be described to further clarify the details of the discharge gap forming layer 5.

  In manufacturing the ESD protection device 1, first, an insulating ceramic green sheet for forming the insulating substrate 2 is prepared. A plurality of insulating ceramic green sheets are laminated to form a first insulator layer. As shown in a plan view in FIG. 2, the first discharge electrode paste 3A is applied onto the first insulator layer 2A by an appropriate method such as screen printing.

  Next, the discharge gap forming layer paste 5A is similarly applied by screen printing or the like. Further, the second discharge electrode paste 4A for forming the second discharge electrode is similarly applied by screen printing or the like. Thereafter, a plurality of insulating ceramic green sheets are laminated to form a second insulator layer.

  By firing the laminated body thus obtained, the insulating substrate 2 shown in FIG. 1 can be obtained. That is, the insulating substrate 2 is obtained by firing the first and second insulator layers. At the same time, in the firing step, the first and second discharge electrode pastes 3A and 4A are baked to form the first and second discharge electrodes 3 and 4. Therefore, the insulating substrate 2 and the first and second discharge electrodes 3 and 4 can be formed by using the lamination and integral firing technique used in the production of the multilayer ceramic electronic component.

  The external electrodes 6 and 7 can be formed by applying and baking a conductive paste on the end faces 2c and 2d after obtaining the insulating substrate 2. Alternatively, the external electrodes 6 and 7 may be formed by vapor deposition, plating or sputtering.

  By the way, the formation of the cavity 5a can be achieved by including in the discharge gap forming layer paste 5A a material that disappears upon firing. This will be described with reference to FIGS.

  FIG. 3A shows the first and second discharge electrode pastes 3A and 4A and the discharge gap forming layer paste 5A sandwiched therebetween. In the state before firing, the discharge gap forming layer paste 5 </ b> A has resin beads 11 and ceramic powder 12. The resin beads 11 are made of a material that can disappear at the firing temperature when firing the insulating substrate 2. The resin constituting the resin beads 11 is not particularly limited as long as it disappears upon firing. As such a resin, appropriate synthetic resin beads such as acrylic resin beads and polystyrene beads can be used.

  The ceramic used as the ceramic powder 12 is not particularly limited as long as the insulating substrate 2 can be obtained by firing so long as the columnar portion 5b around the cavity 5a can be formed. As such ceramics, it is desirable to use the same ceramic material as the material constituting the insulating substrate 2. Thereby, the adhesion strength between the columnar part around the cavity and the remaining part of the insulating substrate 2 is increased.

  However, the ceramic powder 12 may be composed of other insulating ceramics or glass ceramics. The discharge gap forming layer paste 5A includes resin beads 11, ceramic powder 12, and a binder resin and a solvent as necessary.

  The height-direction dimension of the resin beads 11 is a large factor that determines the facing distance between the first discharge electrode 3 and the second discharge electrode 4. Therefore, what is necessary is just to select the height direction dimension of the resin bead 11 according to the height direction dimension of the cavity 5a finally formed. When firing for obtaining the insulating substrate 2 proceeds, the state of FIG. 3A shifts to the state of FIG. 3B and the state of FIG. That is, the resin beads 11 disappear when heated. As a result, a cavity 5a is formed as shown in FIG. Further, when the firing proceeds, the ceramic powders 12 are sintered, and the columnar portion 5b shown in FIG. 3C is formed.

  In this way, the insulating substrate 2 is completed. That is, as described above, the cavity 5a can be easily and reliably formed by using the resin beads 11 that can disappear upon firing. In addition, high-cost processing methods such as photolithography and trimming using a laser are not required. Therefore, the cost of the ESD protection device 1 is hardly increased.

  In the above embodiment, the resin beads 11 are used. However, the resin beads 11 are not limited to the resin as long as it is a solid material that can disappear upon firing. For example, a wax having a certain degree of hardness may be used.

  Furthermore, it is not limited to a bead shape as long as it is a solid that disappears upon firing. For example, a columnar resin material may be used instead of the resin beads 11. That is, as long as the cavity 5a can be formed, the shape of the solid material that can disappear is not limited.

  In the above embodiment, the columnar portion 5b is formed of the insulating ceramic powder 12. However, an auxiliary electrode may be formed on the columnar portion 5b, and in this case, the discharge start voltage is further reduced. This is preferable.

  In the above embodiment, the second discharge electrode 4 is located at the same height as the first discharge electrode 3 on the end face 2d side, and the discharge gap forming layer 5 of the central portion of the insulating substrate 2 is provided. The height position changes so as to reach the upper surface.

  On the other hand, as in the modification shown in FIG. 4, the second discharge electrode 4 may be drawn from the upper surface of the discharge gap forming layer 5 to the end surface 2 d while maintaining its height position. Such a structure includes, for example, a discharge electrode paste for forming the first discharge electrode 3, a ceramic green sheet including a material portion constituting the discharge gap forming layer 5, and a second discharge electrode paste for the discharge electrode 4. It can be obtained by sequentially laminating and firing. Alternatively, a first discharge electrode paste is printed on a ceramic green sheet, a ceramic green sheet having an opening is laminated, a discharge gap forming layer material is printed in the opening, and a second discharge electrode For example, a method of printing the discharge electrode paste constituting 4 may be used. By using such a method, the second discharge electrode 4 can be positioned in a plane in which the upper surface of the discharge gap forming layer 5 is located.

  5 and 6 are partially cutaway enlarged front sectional views for explaining a method of forming the auxiliary electrode. 5 and 6 show the state during firing shown in FIG. 3B in the above-described embodiment.

  As a method of forming the auxiliary electrode, as shown in FIG. 5, it is desirable to mix the semiconductor ceramic powder 13 in addition to the insulating ceramic powder 12 in the discharge gap forming layer paste. As the semiconductor ceramic powder 13, a semiconductor ceramic powder can be preferably used. Moreover, instead of the semiconductor ceramic powder, conductive particles coated with an insulating material may be used. Preferably, it is desirable to use both the semiconductor ceramic powder and the conductive particles coated with an insulating material. Thereby, the discharge start voltage can be further reduced.

  As the semiconductor ceramic powder as the auxiliary electrode material, for example, a ceramic powder made of a semiconductor ceramic such as a carbide such as SiC or an oxide of a transition metal such as MnO, NiO, CoO, or CuO can be preferably used.

  Preferably, as shown in FIG. 6, it is desirable to use the semiconductor ceramic powder 13 in combination with the conductive particles 14 with insulating coating.

  Further, the conductive particles coated with the insulating material as the auxiliary electrode material are not particularly limited. That is, appropriate conductive particles such as Au, Al, Ag, and Ni can be used. The insulating coating may also have a configuration in which very small insulating particles are attached to the surface of the conductive particles. Alternatively, so-called core-shell structured particles in which conductive particles are housed in an insulating film may be used.

  High dielectric constant material particles having a dielectric constant higher than that of the material constituting the insulating substrate 2 may be dispersed in the columnar portion 5b. In that case, the discharge start voltage can be further effectively reduced. Such high dielectric constant material particles may be used in combination with the auxiliary electrode material.

  As the high dielectric constant material as described above, a ceramic having a higher dielectric constant than the ceramic constituting the insulating substrate 2 can be preferably used. For example, a high dielectric constant material such as barium titanate or calcium zirconate can be used.

  In the above embodiment, as shown in FIGS. 3A to 3C, the cavity 5 a is formed by the disappearance of one resin bead 11. On the other hand, as shown in FIGS. 7A to 7C, the discharge gap forming layer paste 5A may be applied twice, and the plurality of resin beads 11 may be stacked in the height direction. In this case, the discharge gap forming layer paste 5A is first applied and dried as in the above embodiment. Next, the discharge gap forming layer paste 5A may be applied again and dried. In this way, a layer in which a plurality of resin beads 11 overlap in the height direction can be formed. After that, if it is fired, it changes as shown in FIGS. 7 (b) and 7 (c). Accordingly, it is possible to form the cavity 5a having a larger dimension in the height direction.

  Thus, in the manufacturing method of the present invention, it is possible to apply the discharge gap forming layer paste a plurality of times, thereby forming a larger discharge gap.

  Further, as described above, the discharge gap forming layer 5 does not need to be formed only in a region where the first discharge electrode 3 and the second discharge electrode 4 are opposed to each other in the height direction, and protrudes to the side. I explained that it may be. Thereby, simplification of positioning in the manufacturing process can be achieved. This will be described with reference to FIGS.

  As shown in FIGS. 8 and 9, a first discharge electrode paste 3A, a discharge gap forming layer paste 5A, and a second discharge electrode paste 4A are stacked on the first insulator layer 2A. In FIG. 9, the direction in which the first and second discharge electrode pastes 3A and 4A extend is defined as the length direction, and the direction orthogonal to the length direction is defined as the width direction.

  The width direction dimension of the discharge gap forming layer paste 5A is set larger than the width direction dimension of the first discharge electrode paste 3A. The coating width of the second discharge electrode paste 4A is also made smaller than the width direction dimension of the discharge gap forming layer paste 5A. In this way, the discharge gap forming layer paste 5A can be applied without being positioned on the first discharge electrode paste 3A with high accuracy. Further, positioning at the time of application of the second discharge electrode paste 4A can be easily performed.

  As in the modification shown in FIG. 10, the width of the discharge gap forming layer paste 5A is set to the width of the first and second discharge electrode pastes 3A and 4A for forming the first and second discharge electrodes. May be the same. In that case, the amount of the material used for the discharge gap forming layer paste 5A can be reduced.

  In the above-described embodiment, the size of the discharge gap region can be adjusted by changing the distance in the facing direction between the first discharge electrode 3 and the second discharge electrode 4.

  On the other hand, in the structure shown in FIGS. 9 and 10, the area of the discharge gap portion is adjusted by adjusting the position in the width direction of the first and second discharge electrode pastes 3A and 4A. be able to. Thus, the dimensions of the region where the discharge electrodes overlap in the width direction may be different.

  In the above-described embodiment, the first discharge electrode 3 and the second discharge electrode 4 are arranged in the insulating substrate 2, but a plurality of pairs of discharge electrodes may be arranged in the insulator. .

  Next, the present invention will be clarified based on specific experimental examples.

Example 1
A ceramic powder having a composition of a BAS material containing Ba, Al, and Si as main components was prepared. To this ceramic powder, toluene as a solvent, a binder resin, and a plasticizer were added and mixed. In this way, a ceramic slurry was obtained. The obtained ceramic slurry was molded by a doctor grade method to obtain an insulating ceramic green sheet having a thickness of 50 μm.

(Discharge electrode paste)
A solvent was added to a composition containing 30% by volume of Cu powder having an average particle diameter of 2 μm and 70% by volume of ethyl cellulose as a binder resin, and mixed to obtain a discharge electrode paste.

(Discharge gap forming layer paste)
BAS calcined powder having an average particle diameter of 1 μm and resin beads made of acrylic resin having an average particle diameter of 5 μm were blended at a volume ratio of 70:30, and a binder resin and a solvent were further added and mixed. In the discharge gap forming layer paste thus obtained, the binder resin and the solvent accounted for 70% by volume of the total, and the BAS calcined powder and acrylic resin beads accounted for the remaining 30% by volume. Therefore, the portion remaining as the columnar portion 5b after firing is the BAS calcined powder portion, and the acrylic resin bead portion forms the cavity 5a.

(Manufacturing process)
A plurality of insulating ceramic green sheets prepared as described above were laminated. Next, the discharge electrode paste was applied to a thickness of about 7 μm. Next, the discharge gap forming layer paste was applied to a thickness of about 8 μm. Thereafter, the discharge electrode paste was applied again to a thickness of about 7 μm.

  In this case, the area of the rectangular portion where the discharge electrode pastes overlap with each other via the discharge gap forming layer paste was 150 μm × 100 μm.

  Next, a plurality of the insulating ceramic green sheets were further laminated. Thereafter, pressure was applied in the thickness direction to obtain a laminate. In this way, a laminate having a thickness of 0.3 mm was obtained. Before pressurization, the portion of the laminate where the discharge gap forming layer paste is formed is thicker than the other portions. By applying the pressure, the thickness of the second discharge electrode 4 becomes uniform, and the second discharge electrode 4 may be bent as shown in FIG. Further, not only the second discharge electrode 4 but also the first discharge electrode 3 may be bent.

  In addition, about each said process, it performed using the insulating ceramic green sheet | seat of the mother for obtaining the insulator of a some ESD protection device. The mother laminate thus obtained was then cut in the thickness direction to obtain a laminate of 1 unit of each ESD protection device. That is, a laminate having a planar shape of 1.0 mm × 0.5 mm was obtained.

  Next, the laminate was fired at a temperature of 1000 ° C. or lower. After firing, a conductive paste was applied to both end faces of the insulator and baked. Thereby, the external electrodes 6 and 7 shown in FIG. 1 were formed. In this way, an ESD protection device was obtained.

  When the ESD protection device was cut and the inside was observed with a metal microscope, it was confirmed that a plurality of cavities 5a were formed by the disappearance of the resin beads.

(Example 2)
An ESD protection device was obtained in the same manner as in Example 1 except that the discharge gap forming layer paste was changed as follows.

  As a paste for a discharge gap forming layer, BAS calcined powder having an average particle diameter of 1 μm, SiC powder having an average particle diameter of 1 μm, and acrylic resin beads having an average particle diameter of 5 μm in a ratio (volume ratio) of 35:35:30 Further, a binder resin and a solvent were added and mixed. In this way, a discharge gap forming layer paste was obtained.

  In this discharge gap forming layer paste, the binder resin and the solvent occupy 70% by volume, and the remaining 30% by volume is occupied by BAS calcined powder, SiC powder, and acrylic resin beads. The BAS calcined powder and the SiC powder as the semiconductor ceramic powder constitute the columnar part, and the acrylic resin beads are materials that form cavities by disappearance.

  The ESD protection device obtained in Example 2 was cut in the same manner as in Example 1 and observed with a metal microscope. As a result, it was confirmed that a plurality of cavities were formed inside. Further, when the cut surface was observed at 2000 to 5000 times with an electron microscope, a portion derived from SiC powder as the semiconductor ceramic powder was confirmed in the columnar portion around the cavity.

(Comparative example)
Instead of the discharge gap forming layer paste used in Example 1, a resin paste that disappears upon firing was used. The other points were the same as in Example 1. After firing, the insulator was cut and observed. As a result, the resin paste disappeared between the first and second discharge electrodes, and a large single cavity was formed. That is, the first and second discharge electrodes are located above and below a large single cavity.

(Evaluation of Examples and Comparative Examples)
The discharge start voltages of the ESD protection devices obtained in Examples 1 and 2 and the comparative example were measured.

  Measurement of discharge start voltage: According to IEC61000-4-2, ESD of voltages of 2 kV, 4 kV, 6 kV and 8 kV was applied in this order by contact discharge. When the ESD protection device was discharged, a circle is shown in Table 1 below, and a case where the discharge did not occur and the device did not operate was indicated by x.

  As is clear from Table 1, in the comparative example, the discharge was not started when 6 kV ESD was applied. On the other hand, in Example 1 and Example 2, it turns out that a discharge start voltage can be lowered significantly. In particular, in Example 2 in which the semiconductor ceramic powder was added as the auxiliary electrode material, it was possible to further reduce the discharge start voltage as compared with Example 1.

DESCRIPTION OF SYMBOLS 1 ... ESD protection apparatus 2 ... Insulating substrate 2A ... 1st insulator layer 2a ... Upper surface 2b ... Lower surface 2c, 2d ... End surface 3 ... 1st discharge electrode 4 ... 2nd discharge electrode 3A ... 1st discharge electrode Paste 4A ... second discharge electrode paste 5 ... discharge gap forming layer 5A ... discharge gap forming layer paste 5a ... cavity 5b ... columnar portions 6, 7 ... external electrode 11 ... resin beads 12 ... ceramic powder 13 ... semiconductor ceramic powder 14 ... Conductive particles

Claims (10)

An insulator which is a laminated insulating substrate having an upper surface and a lower surface ;
The first and second discharge electrodes having a surface parallel to the upper surface and the lower surface of the insulator, and facing and separated in the height direction in the insulator;
In the portion where the first discharge electrode and the second discharge electrode face each other, the discharge gap forming layer sandwiched between the first discharge electrode and the second discharge electrode has the first discharge electrode. A plurality of cavities connected to the discharge electrode and the second discharge electrode are provided,
An auxiliary electrode is provided on the discharge gap forming layer,
In top view,
The first discharge electrode has first and second corners at the tip, and one of the first and second corners overlaps the second discharge electrode. The other corner and the second discharge electrode do not overlap ,
The second discharge electrode has third and fourth corners at the tip, and one of the third and fourth corners overlaps with the first discharge electrode. An ESD protection device in which the other corner and the first discharge electrode do not overlap . The ESD protection device according to claim 1, wherein the auxiliary electrode includes semiconductor ceramic particles. It said auxiliary electrode comprises a conductive particles coated with insulating material, ESD protection device according to claim 1 or 2. The discharge gap forming layer comprising said high dielectric constant material having a higher dielectric constant than the insulating material constituting the insulator, ESD protection device according to any one of claims 1-3. Applying a first discharge electrode paste on the first insulator layer so as to have first and second corners at the tip;
Applying a discharge gap forming layer paste containing a solid and an auxiliary electrode material that disappears by firing on a part of the first discharge electrode paste;
The second discharge electrode paste is disposed so as to face the first discharge electrode paste through at least part of the discharge gap forming layer paste and to have third and fourth corners at the tip. Applying step;
Forming a second insulator layer so as to cover the second discharge electrode paste;
The first and second insulator layers are baked to form an insulator, and the first discharge electrode paste, the discharge gap forming layer paste, and the second discharge electrode paste are baked, A first discharge electrode having a second corner, a second discharge electrode having a third and a fourth corner, and the first and second discharge electrodes. A firing step of forming a discharge gap forming layer having a plurality of cavities and auxiliary electrodes connected to the discharge electrode and the second discharge electrode,
In the step of applying the second discharge electrode paste, when viewed from above, either one of the first and second corners of the first discharge electrode paste and the second discharge electrode The paste overlaps , the other corner does not overlap the second discharge electrode paste, and one of the third and fourth corners of the second discharge electrode paste A method for manufacturing an ESD protection device, wherein the second discharge electrode paste is applied so that the first discharge electrode paste overlaps and the other corner does not overlap the first discharge electrode paste. The manufacturing method of the ESD protection apparatus according to claim 5 , wherein the solid disappearing by firing is made of a resin. The manufacturing method of the ESD protection apparatus according to claim 6 , wherein the solid disappearing by firing is made of resin beads. The auxiliary electrode material comprises a semiconductor ceramic particles, method for manufacturing the ESD protection device according to any one of claims 5-7. The auxiliary electrode material comprises a coated conductive particles with an insulating material, method of manufacturing the ESD protection device according to any one of claims 5-8. The method for manufacturing an ESD protection device according to any one of claims 5 to 9 , wherein the discharge gap forming layer paste includes a high dielectric constant material having a higher dielectric constant than a material constituting the insulator. .

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