JP2023001474A - Transient voltage protection device - Google Patents

Abstract

To provide a transient voltage protection device capable of controlling a region where discharge is generated.SOLUTION: A transient voltage protection device 1 comprises: an element body 2; an internal electrode 5 and an internal electrode 6 provided in the element body 2 so as to be away from each other; an external electrode 3 connected with the internal electrode 5; an external electrode 4 connected with the internal electrode 6; and a discharge auxiliary part 7 containing a metal, contacted with the internal electrode 5 and the internal electrode 6, and provided in the element body 2 so as to connect between the internal electrode 5 and the internal electrode 6. The discharge auxiliary part 7 has at least a first region R1 and a second region R2. A metal concentration of the first region R1 is higher than that of the second region R2.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to transient voltage protection devices.

Patent Document 1 discloses an ESD including a ceramic multilayer substrate, a pair of discharge electrodes facing each other in the ceramic multilayer substrate, a pair of external electrodes connected to the pair of discharge electrodes, and an auxiliary electrode containing a conductive material. (Electro-Static Discharge) protection devices are described. In this ESD protection device, since the auxiliary electrode is provided in the region connecting the pair of discharge electrodes, it is possible to efficiently generate discharge and improve ESD responsiveness.

WO2009/098944

In the ESD protection device described in Patent Literature 1, the discharge electrode may be deteriorated due to concentration of the electric field on a part of the discharge electrode.

One aspect of the present disclosure provides a transient voltage protection device capable of controlling the area that causes the discharge.

A transient voltage protection device according to an aspect of the present disclosure includes a base body, a first internal electrode and a second internal electrode spaced apart from each other and provided in the base body, and a first external electrode connected to the first internal electrode. and a second external electrode connected to the second internal electrode; a discharge assisting part provided within the body, the discharge assisting part having at least a first region and a second region, the metal concentration of the first region being higher than the metal concentration of the second region.

In the above transient voltage protection device, the discharge auxiliary part has at least a first region and a second region, the metal concentration of the first region being higher than the metal concentration of the second region. The susceptibility of discharge to occur changes according to the metal concentration of the discharge auxiliary portion. Therefore, by controlling the arrangement of the first area and the second area, it is possible to control the area in which the discharge is generated.

In the above transient voltage protection device, the first internal electrode has a first corner facing the second internal electrode, and the second internal electrode has a second corner facing the first internal electrode. and the second region may be provided so as to be in contact with the first corner and the second corner. In this case, it is possible to suppress the discharge at the first corner and the second corner where the electric field tends to concentrate. Therefore, deterioration of the first internal electrode and the second internal electrode is suppressed.

In the above transient voltage protection device, the first internal electrode and the second internal electrode each have side edges extending along the first direction, and the side edges cross each other in the first direction. The first region is provided so as to face each other in the direction, and the first region is provided so as to be separated from the first corner and the second corner and to be in contact with the side edge portions of the first internal electrode and the second internal electrode. may be In this case, it is possible to promote discharge between the side edge of the first internal electrode and the side edge of the second internal electrode while suppressing the discharge at the first corner and the second corner. Therefore, it is possible to achieve a high ESD tolerance while suppressing deterioration of the first internal electrode and the second internal electrode.

In the above transient voltage protection device, the first internal electrode and the second internal electrode extend along the first direction, and are provided so that the tips in the first direction face each other in the first direction, The one region may be provided so as to be spaced apart from the first corner and the second corner and to be in contact with tip portions of the first internal electrode and the second internal electrode. In this case, discharge can be promoted between the tip of the first internal electrode and the tip of the second internal electrode while suppressing the discharge at the first corner and the second corner. Therefore, it is possible to achieve a high ESD tolerance while suppressing deterioration of the first internal electrode and the second internal electrode.

The transient voltage protection device may further comprise a cavity provided within the element body, and the first internal electrode and the second internal electrode may face the cavity. In this case, since discharge is likely to occur due to the hollow portion, a high ESD tolerance can be achieved.

In the transient voltage protection device described above, the cavity may include a gap region located between the first internal electrode and the second internal electrode. In this case, discharge can be reliably generated in the gap region.

According to one aspect of the present disclosure, it is possible to control the region in which discharge is generated.

1 is a perspective view showing a transient voltage protection device according to an embodiment; FIG. 2 is an exploded perspective view of the transient voltage protection device of FIG. 1; FIG. FIG. 3 is a perspective view of the transient voltage protection device of FIG. 1 viewed from the stacking direction. 4 is a cross-sectional view taken along line IV-IV of FIG. 1. FIG. FIG. 5 is a perspective view of the transient voltage protection device according to the first modification as seen from the stacking direction. FIG. 6 is a perspective view of the transient voltage protection device according to the second modification as seen from the stacking direction. FIG. 7 is a perspective view of the transient voltage protection device according to the third modification as seen from the stacking direction. FIG. 8 is a perspective view of a transient voltage protection device according to a fourth modification, viewed from the stacking direction. FIG. 9 is a perspective view of a transient voltage protection device according to a fifth modification, viewed from the stacking direction. FIG. 10 is a perspective view of the transient voltage protection device according to the sixth modification as seen from the stacking direction.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and overlapping descriptions are omitted.

A transient voltage protection device 1 according to the present embodiment shown in FIGS. 1 to 4 is an electronic component mounted in an electronic device (not shown) to protect the electronic device from transient voltages such as ESD. The electronic equipment to be protected is, for example, a circuit board or an electronic component. The transient voltage protection device 1 includes an element body 2, a pair of external electrodes 3, 4, a pair of internal electrodes 5, 6, a discharge auxiliary portion 7, and a cavity portion S. The internal electrodes 5, 6 are discharge electrodes configured to discharge. The internal electrodes 5 and 6 together with the discharge auxiliary portion 7 and the cavity portion S constitute a transient voltage suppressor. A transient voltage suppressor has transient voltage absorption capability.

The element body 2 has a rectangular parallelepiped shape. The rectangular parallelepiped shape includes, for example, a rectangular parallelepiped shape with chamfered corners and edges, and a rectangular parallelepiped shape with rounded corners and edges. The element body 2 has, as outer surfaces, a pair of end faces 2a and 2b facing each other, a pair of side faces 2c and 2d facing each other, and a pair of side faces 2e and 2f facing each other. are doing. The four side surfaces 2c, 2d, 2e, and 2f are adjacent to the end surfaces 2a and 2b, respectively, and extend in opposite directions to the end surfaces 2a and 2b so as to connect the end surfaces 2a and 2b. One of the four side surfaces 2c, 2d, 2e, and 2f is defined as a mounting surface facing the electronic device to be protected.

In this embodiment, the facing direction of the end faces 2a and 2b is defined as a first direction D1, the facing direction of the side surfaces 2e and 2f is defined as a second direction D2, and the facing direction of the side surfaces 2c and 2d is defined as a third direction D3. The first direction D1 is the length direction of the element body 2 , the second direction D2 is the width direction of the element body 2 , and the third direction D3 is the height direction of the element body 2 . The length of the element 2 (the length of the element 2 in the first direction D1) is, for example, 0.6 mm or more and 2.0 mm or less. The width of the element 2 (the length of the element 2 in the second direction D2) is, for example, 0.3 mm or more and 1.2 mm or less. The height of the element 2 (the length of the element 2 in the third direction D3) is, for example, 0.3 mm or more and 1.2 mm or less.

The element body 2 has a plurality of insulator layers 10 laminated in the third direction D3. Each insulator layer 10 has a rectangular plate shape. Each insulator layer 10 is an insulator having electrical insulation, and is composed of a sintered insulator green sheet. In the actual element body 2, the insulator layers 10 are integrated to such an extent that the boundaries therebetween cannot be visually recognized.

The insulator layer 10 is made of _{Fe2O3 ,} NiO, CuO, ZnO, MgO, _SiO2 , _TiO2 , _{MnCO3 , SrCO3} , _CaCO3 , _BaCO3 , _{Al2O3 , ZrO2} , B2O3 _, or the like. of ceramic material. The insulator layer 10 may be composed of a single ceramic material, or may be composed of a mixture of two or more ceramic materials. The insulator layer 10 may contain glass. The insulator layer 10 may contain copper oxide (CuO, Cu ₂ O) to enable low temperature sintering.

External electrodes 3 and 4 are provided on the outer surface of element body 2 . The external electrodes 3 and 4 are arranged on the element body 2 so as to face each other in the first direction D1. The external electrodes 3 and 4 are provided on both ends of the element body 2 in the first direction D1. The external electrodes 3, 4 are separated from each other in the first direction D1.

The external electrode 3 is provided on the end surface 2 a and connected to the internal electrode 5 . The external electrode 3 is formed so as to cover the end surface 2a and partially wrap around the side surfaces 2c, 2d, 2e, and 2f. The external electrodes 3 are provided on the entire surface of the end surface 2a and the ends of the side surfaces 2c, 2d, 2e, and 2f on the side of the end surface 2a.

The external electrode 4 is provided on the end surface 2 b and connected to the internal electrode 6 . The external electrode 4 is formed so as to cover the end face 2b and partially wrap around the side faces 2c, 2d, 2e, and 2f. The external electrodes 4 are provided on the entire surface of the end surface 2b and the ends of the side surfaces 2c, 2d, 2e, and 2f on the side of the end surface 2b.

The internal electrodes 5 and 6 are provided inside the element body 2 so as to be spaced apart from each other. The internal electrodes 5, 6 extend along the first direction D1. The internal electrodes 5 and 6 are arranged with an interval in the second direction D2. The internal electrodes 5 and 6 are provided such that side edge portions 5c and 6c, which will be described later, face each other in the second direction D2. The internal electrodes 5 and 6 face each other in the second direction D2 via a gap region Sg which will be described later. The internal electrode 5 is arranged closer to the side surface 2e. The internal electrode 6 is arranged closer to the side surface 2f. The internal electrodes 5 and 6 are arranged at the same height position (that is, the same lamination position) in the third direction D3. The internal electrodes 5 and 6 are arranged on the same insulator layer 10 as each other. The internal electrodes 5 and 6 are provided substantially in the center in the stacking direction (third direction D3).

The internal electrodes 5 and 6 have a rectangular shape with the first direction D1 as the longitudinal direction in a plan view (that is, when viewed from the third direction D3). The internal electrodes 5 and 6 have, for example, the same shape. The length of the internal electrodes 5 and 6 (the length of the internal electrodes 5 and 6 in the first direction D1) is, for example, 0.5 mm or more and 1.6 mm or less. The width of the internal electrodes 5 and 6 (the length of the internal electrodes 5 and 6 in the second direction D2) is, for example, 0.1 mm or more and 0.5 mm or less. The thickness of the internal electrodes 5 and 6 (the length of the internal electrodes 5 and 6 in the third direction D3) is, for example, 3 μm or more and 20 μm or less.

The internal electrodes 5 are exposed on the end face 2a and provided apart from the end face 2b and the side faces 2c, 2d, 2e and 2f. The internal electrode 5 has a connection end (connection end surface) 5a, a tip portion 5b, a pair of side edges 5c and 5d, a first surface 5e, and a second surface 5f.

The connection end 5a is exposed on the end face 2a and connected to the external electrode 3. As shown in FIG. The distal end portion 5b constitutes an end portion opposite to the external electrode 3 in the first direction D1. The tip portion 5b is separated from the outer surface of the base body 2. As shown in FIG. The distal end portion 5b is defined as a region including not only the distal end face but also the vicinity of the distal end face. The tip portion 5b includes end portions near the tip surface of each of the first surface 5e, the second surface 5f, the side edge portion 5c, and the side edge portion 5d. The distal end portion 5b has a predetermined thickness in the extending direction of the internal electrode 5 (first direction D1).

The side edges 5c and 5d face each other in the second direction D2. The side edge portion 5c is arranged closer to the side surface 2f, and the side edge portion 5d is arranged closer to the side surface 2e. The side edges 5c and 5d extend along the first direction D1. The side edge portions 5c and 5d are defined as regions including not only both ends of the internal electrode 5 in the second direction D2 (side surfaces facing the second direction D2) but also portions near both ends. The side edges 5c and 5d include the ends of the first surface 5e and the second surface 5f in the second direction D2. The side edges 5c and 5d have a predetermined thickness in the second direction D2. The side edge portion 5c faces a gap region Sg, which will be described later.

The first surface 5 e is in contact with the auxiliary discharge portion 7 . The second surface 5f faces the first surface 5e in the third direction D3. The second surface 5f faces a region of the hollow portion S other than the gap region Sg.

The internal electrode 6 is exposed on the end surface 2b and provided apart from the end surface 2a and the side surfaces 2c, 2d, 2e and 2f. The internal electrode 6 has a connection end (connection end surface) 6a, a tip portion 6b, a pair of side edges 6c and 6d, a first surface 6e, and a second surface 6f.

The connection end 6a is exposed at the end surface 2b and connected to the external electrode 4. As shown in FIG. The distal end portion 6b constitutes an end portion opposite to the external electrode 4 in the first direction D1. The tip portion 6b is separated from the outer surface of the base body 2. As shown in FIG. The distal end portion 6b is defined as a region including not only the distal end face but also the vicinity of the distal end face. The tip portion 6b includes end portions near the tip surface of each of the first surface 6e, the second surface 6f, the side edge portion 6c, and the side edge portion 6d. The tip portion 6b has a predetermined thickness in the extending direction of the internal electrode 6 (first direction D1).

The side edges 6c and 6d face each other in the second direction D2. The side edge portion 6c is arranged closer to the side surface 2e, and the side edge portion 6d is arranged closer to the side surface 2f. The side edges 6c and 6d extend along the first direction D1. The side edge portions 6c and 6d are defined as regions including not only both ends of the internal electrode 6 in the second direction D2 (side surfaces facing the second direction D2) but also portions near both ends. The side edges 6c and 6d include ends in the second direction D2 of the first surface 6e and the second surface 6f. The side edges 6c and 6d have a predetermined thickness in the second direction D2. The side edge portion 6c faces a gap region Sg, which will be described later.

The first surface 6 e is in contact with the auxiliary discharge portion 7 . The second surface 6f faces the first surface 6e in the third direction D3. The second surface 6f faces a region of the hollow portion S other than the gap region Sg.

The internal electrode 5 has a corner portion 5 g facing the internal electrode 6 . In this embodiment, the internal electrode 5 has one corner 5g. The corner portion 5g is one of the four corner portions positioned at the four corners of the internal electrode 5 when viewed from the third direction D3. The corner portion 5g is located at the end portion of the tip portion 5b near the internal electrode 6 . It can also be said that the corner portion 5g is located at the end portion of the side edge portion 5c nearer to the tip surface. The corner portion 5g is provided at a position spaced apart from the outer surface of the base body 2. As shown in FIG. The corner 5g is defined as an area including the corresponding corner of the first surface 5e and the corresponding corner of the second surface 5f. The corner portion 5g faces the side edge portion 6c in the second direction D2. The distance in the second direction D2 between the corner portion 5g and the side edge portion 6c is equal to the shortest distance between the internal electrodes 5,6.

The internal electrode 6 has a corner portion 6 g facing the internal electrode 5 . In this embodiment, the internal electrode 6 has one corner 6g. The corner portion 6g is one of the four corner portions positioned at the four corners of the internal electrode 6 when viewed from the third direction D3. The corner portion 6g is located at the end portion of the tip portion 6b near the internal electrode 5 . It can also be said that the corner portion 6g is positioned at the end portion of the side edge portion 6c nearer to the tip surface. The corner portion 6g is provided at a position spaced apart from the outer surface of the base body 2. As shown in FIG. The corner 6g is defined as an area including the corresponding corner of the first surface 6e and the corresponding corner of the second surface 6f. The corner portion 6g faces the side edge portion 5c in the second direction D2. The distance in the second direction D2 between the corner portion 6g and the side edge portion 5c is equal to the shortest distance between the internal electrodes 5,6.

The external electrodes 3, 4 and the internal electrodes 5, 6 are made of a conductor material containing Ag, Pd, Au, Pt, Cu, Ni, Al, Mo, W, for example. Ag/Pd alloy, Ag/Cu alloy, Ag/Au alloy, Ag/Pt alloy, etc., can be used for the external electrodes 3, 4 and the internal electrodes 5, 6, for example. The external electrodes 3, 4 and the internal electrodes 5, 6 may be made of the same material, or may be made of different materials.

The external electrodes 3 and 4 are formed, for example, by applying a conductive paste containing the conductive material to the outer surface of the element body 2 and then baking the conductive paste. The external electrodes 3 and 4 may have plating layers. The internal electrodes 5 and 6 are formed, for example, by applying a conductive paste containing the conductive material on the insulating green sheets by printing, and then firing the conductive paste together with the insulating green sheets.

The discharge auxiliary part 7 is provided inside the element body 2 . The auxiliary discharge portion 7 has a rectangular shape in a plan view (that is, when viewed from the third direction D3), the longitudinal direction of which is the first direction D1. The length of the auxiliary discharge portion 7 (the length of the auxiliary discharge portion 7 in the first direction D1) is, for example, 0.4 mm or more and 1.5 mm or less. The width of the auxiliary discharge portion 7 (the length of the auxiliary discharge portion 7 in the second direction D2) is, for example, 0.15 mm or more and 0.95 mm or less. The thickness of the auxiliary discharge portion (the length of the auxiliary discharge portion in the third direction D3) is, for example, 3 μm or more and 20 μm or less.

The auxiliary discharge part 7 is provided apart from the outer surface of the element body 2 so as not to be exposed from the element body 2 . The discharge auxiliary portion 7 is in contact with the internal electrodes 5 and 6 and connects the internal electrodes 5 and 6 to each other. The discharge auxiliary portion 7 extends to the outside of the internal electrodes 5 and 6 in the second direction D2. The auxiliary discharge portion 7 has a portion exposed from the internal electrodes 5 and 6 and facing the gap region Sg.

The discharge auxiliary part 7 contains an insulator and metal particles (metal). The insulator is made of, for example, a ceramic material. Ceramic materials include, for example, _{Fe2O3 ,} NiO, CuO, ZnO, MgO, _SiO2 , _TiO2 , _MnCO3 , SrCO3, _{CaCO3 , BaCO3} , _{Al2O3 , ZrO2} , or _B2O . ₃ is mentioned. The auxiliary discharge portion 7 may contain only one of these ceramic materials, or may contain a mixture of two or more of them. The metal particles are composed of Ag, Pd, Au, Pt, Ag/Pd alloy, Ag/Cu alloy, Ag/Au alloy, or Ag/Pt alloy, for example. The discharge auxiliary part 7 may contain semiconductor particles such as RuO ₂ . The discharge auxiliary part 7 may contain glass.

The auxiliary discharge portion 7 has at least a first region R1 and a second region R2. The metal concentration of the first region R1 is higher than the metal concentration of the second region R2. The metal concentrations of the pair of second regions R2 are equal to each other, but may be different from each other. The metal concentration of the auxiliary discharge portion 7 is obtained by, for example, SEM-EDS (scanning electron microscope-energy dispersive X-ray spectroscopy) analysis. The metal concentration of the first region R1 is, for example, 1.1 times or more the metal concentration of the second region R2.

In this embodiment, the auxiliary discharge portion 7 has one first region R1 and a pair of second regions R2 that are separated from each other in the first direction D1. The first region R1 is located between the pair of second regions R2 and connects the pair of second regions R2 in the first direction D1. The pair of second regions R2 are arranged on both sides of the first region R1 in the first direction D1 so as to sandwich the first region R1 in the first direction D1. In the second direction D2, the positions of both ends of the first region R1 match the positions of both ends of the second region R2. The discharge auxiliary portion 7 extends to the outside of the tip portions 5b and 6b in the first direction D1.

The first region R1 is provided so as to be spaced apart from the corners 5g and 6g and in contact with part of the side edges 5c and 6c in the first direction D1. The parts of the side edges 5c and 6c in the first direction D1 are the parts of the side edges 5c and 6c that are separated from the corners 5g and 6g in the first direction D1. When viewed from the third direction D3, the first region R1 overlaps part of the side edges 5c and 6c in the first direction D1.

The second region R2 is provided so as to contact the corners 5g and 6g. One second region R2 is provided so as to be in contact with the corner portion 5g. One of the second regions R2 is also in contact with corner portions other than the corner portion 5g of the tip portion 5b. One second region R2 is in contact with the entire portion of the first surface 5e included in the tip portion 5b. One of the second regions R2 is arranged so as to overlap the entire tip portion 5b when viewed from the third direction D3.

The other second region R2 is provided so as to be in contact with the corner 6g. The other second region R2 is also in contact with the corners other than the corners 5g of the tip 6b. The other second region R2 is in contact with the entire portion of the first surface 6e included in the tip portion 6b. The other second region R2 is arranged so as to overlap the entire tip portion 6b when viewed from the third direction D3.

The auxiliary discharge part 7 is formed, for example, by applying a slurry containing the above ceramic material and metal particles onto the insulator green sheet by printing, and then firing the slurry together with the insulator green sheet. The first region R1 and the second region R2 can be formed by using two types of slurries with mutually different metal concentrations.

The cavity S is provided inside the element body 2 so as to be in contact with the internal electrodes 5 and 6 . The internal electrodes 5 and 6 face the hollow portion S. The cavity portion S includes a gap region Sg positioned between the internal electrodes 5, 6 in the second direction D2. The width of the gap region Sg (the length of the gap region Sg in the second direction D2), that is, the interval between the internal electrodes 5 and 6 is, for example, 10 μm or more and 70 μm or less. The hollow portion S is provided apart from the outer surface of the element body 2 . The surfaces defining the hollow portion S are the surface of the second surface 5f and the side edge portion 5c of the internal electrode 5, the surface of the second surface 6f and the side edge portion 6c of the internal electrode 6, and the auxiliary discharge portion 7. , and surfaces exposed from the internal electrodes 5 and 6 .

The hollow portion S is located inside the outer edge of the auxiliary discharge portion 7 when viewed from the third direction D3. When viewed from the third direction D3, the hollow portion S is positioned inside the outer edge of the first region R1 and separated from the second region R2. The cavity S is also separated from the corners 5g and 6g. The hollow portion S is shorter than the auxiliary discharge portion 7 in each of the first direction D1 and the second direction D2. Both ends of the hollow portion S in the second direction D2 overlap the side edges 5d and 6d or are positioned inside the side edges 5d and 6d when viewed from the third direction D3. The cavity S is formed by, for example, applying an organic lacquer containing an organic solvent and an organic binder onto the insulating green sheet by printing, and then firing the organic lacquer together with the insulating green sheet to burn off the organic lacquer. be.

As described above, in the transient voltage protection device 1, the discharge auxiliary portion 7 has at least the first region R1 and the second region R2, and the metal concentration of the first region R1 is higher than that of the second region R2. is also expensive. The easiness of occurrence of discharge changes according to the metal concentration of the discharge auxiliary portion 7 . The higher the metal particle concentration, the lower the clamp voltage and the better the transient voltage absorption performance. Therefore, by controlling the arrangement of the first region R1 and the second region R2, it is possible to control the region in which the discharge is generated. For example, the first region R1 can be arranged in a portion where it is desired to promote discharge, and the second region can be arranged in a portion where it is desired to suppress discharge. Since the higher the metal concentration is, the more the heat dissipation effect is improved, the portion where the first region R1 is arranged can further promote the heat dissipation.

The corner 5g faces the internal electrode 6 at the shortest distance, and the electric field tends to concentrate there. The corner 6g faces the internal electrode 5 at the shortest distance, and the electric field tends to concentrate there. The second region R2 is provided so as to contact the corners 5g and 6g. Thereby, the discharge at the corners 5g and 6g can be suppressed. Therefore, deterioration of the internal electrodes 5 and 6 is suppressed. Since the second region R2 also contains metal particles, the heat dissipation effect of the second region R2 can be obtained also at the corners 5g and 6g. Therefore, corners 5g and 6g can be protected.

The internal electrodes 5 and 6 are provided so that side edges 5c and 6c extending along the first direction D1 face each other in a second direction D2 intersecting the first direction D1. The first region R1 is provided so as to be separated from the corners 5g and 6g and in contact with the side edges 5c and 6c. Therefore, it is possible to promote the discharge between the side edges 5c and 6c while suppressing the discharge at the corners 5g and 6g. Therefore, it is possible to achieve a high ESD tolerance while suppressing deterioration of the internal electrodes 5 and 6 . According to the transient voltage protection device 1, both long life and high ESD tolerance can be achieved.

The internal electrodes 5 and 6 face a cavity S provided inside the element body 2 . Therefore, discharge is likely to occur due to the hollow portion S. Therefore, high ESD resistance can be easily achieved. The cavity S includes a gap region Sg positioned between the internal electrodes 5,6. Therefore, discharge can be reliably generated in the gap region Sg.

The discharge auxiliary portion 7 is in contact with the internal electrodes 5 and 6 and connects the internal electrodes 5 and 6 to each other. Therefore, discharge can be reliably generated between the internal electrodes 5 and 6 . The auxiliary discharge portion 7 has a portion exposed from the internal electrodes 5 and 6 and facing the gap region Sg. Therefore, the discharge can be generated between the internal electrodes 5 and 6 more reliably. Since the second surfaces 5f and 6f of the internal electrodes 5 and 6 face the hollow portion S, discharge is likely to occur on the second surfaces 5f and 6f as well. Therefore, a high ESD resistance can be realized more reliably.

The external electrodes 3 and 4 are arranged on the element body 2 so as to face each other in the first direction D1. That is, since the external electrodes 3 and 4 are arranged at both ends of the element body 2 in the first direction D1, it is possible to suppress the occurrence of a short circuit between the external electrodes 3 and 4.

The present invention is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the scope of the invention.

As shown in FIG. 5, the transient voltage protection device 1A according to the first modification differs from the transient voltage protection device 1 (see FIG. 3) in the shape of the second region R2. Here, the transient voltage protection device 1A will be described mainly with respect to the differences from the transient voltage protection device 1, and the description of the common points will be omitted as appropriate.

In the transient voltage protection device 1A, the length of each second region R2 in the second direction D2 is shorter than the length of the first region R1 in the second direction D2. One second region R2 in contact with the corner 5g includes a portion extending to the outside of the internal electrode 5 in the second direction D2, but does not include a portion extending to the outside of the internal electrode 6 in the second direction D2. Not included. One end of the second region R2 in the second direction D2 overlaps the side edge portion 6d when viewed from the third direction D3. The other second region R2 in contact with the corner 6g includes a portion extending to the outside of the internal electrode 6 in the second direction D2, but does not include a portion extending to the outside of the internal electrode 5 in the second direction D2. Not included. One end of the other second region R2 in the second direction D2 overlaps the side edge portion 5d when viewed from the third direction D3.

As shown in FIG. 6, the transient voltage protection device 1B according to the second modification has a transient voltage protection in that the discharge auxiliary part 7 does not extend outside the internal electrodes 5 and 6 in the second direction D2. It differs from device 1 (see FIG. 3). Here, the transient voltage protection device 1B will be mainly described with respect to the differences from the transient voltage protection device 1, and the description of the common points will be omitted as appropriate.

In the transient voltage protection device 1B, one end of the auxiliary discharge portion 7 in the second direction D2 is positioned between the side edge portion 5c and the side edge portion 5d when viewed from the third direction D3. When viewed from the third direction D3, the other end of the auxiliary discharge portion 7 in the second direction D2 is positioned between the side edge portion 6c and the side edge portion 6d. One second region R2 is in contact with the corner portion 5g, but is not in contact with the corner portions other than the corner portion 5g of the tip portion 5b. The other second region R2 is in contact with the corner 6g, but is not in contact with corners other than the corner 6g of the tip portion 6b. The discharge auxiliary portion 7 is positioned inside the hollow portion S in the second direction D2.

As shown in FIG. 7, in the transient voltage protection device 1C according to the third modification, the discharge auxiliary section 7 has a pair of third regions R3 in addition to the first region R1 and the pair of second regions R2. It is different from the transient voltage protection device 1 (see FIG. 3) in that Here, the transient voltage protection device 1C will be described mainly with respect to the differences from the transient voltage protection device 1, and the description of the common points will be omitted as appropriate.

In the transient voltage protection device 1C, the metal concentration of the third region R3 is lower than the metal concentration of the first region R1 and higher than the metal concentration of the second region R2. The metal concentrations of the pair of third regions R3 are equal to each other, but may be different from each other. The third region R3 is arranged between the first region R1 and the second region R2. The third region R3 is separated from the corners 5g and 6g. In the second direction D2, the positions of both ends of the third region R3 match the positions of both ends of the first region R1 and the positions of both ends of the second region R2. In the transient voltage protection device 1C, the metal concentration changes in two steps between the corners 5g and 6g where discharge should be suppressed and the side edges 5c and 6c where discharge should be promoted. You may have

As shown in FIG. 8, the transient voltage protection device 1D according to the fourth modification has rounded corners of the discharge auxiliary portion 7 and shapes of the first region R1 and the second region R2. , which is different from the transient voltage protection device 1 (see FIG. 3). Here, the transient voltage protection device 1D will be described mainly with respect to the differences from the transient voltage protection device 1, and the description of the common points will be omitted as appropriate.

In the transient voltage protection device 1D, the first region R1 does not include portions extending outside the internal electrodes 5, 6 in the second direction D2. Both ends of the first region R1 in the second direction D2 overlap the side edges 5d and 6d when viewed from the third direction D3. The second region R2 has a rectangular frame shape when viewed from the third direction D3, and surrounds the rectangular first region R1 with a substantially uniform width.

As shown in FIG. 9, the transient voltage protection device 1E according to the fifth modification has the transient voltage protection device 1 (see FIG. 3) in terms of the shapes of the first region R1 and the second region R2 (see FIG. 3). ). Here, the transient voltage protection device 1E will be described mainly with respect to the differences from the transient voltage protection device 1, and the description of the common points will be omitted as appropriate.

In transient voltage protection device 1E, first region R1 is in contact with corners 5g and 6g. The first region R1 extends to the outside of the internal electrodes 5 and 6 in the second direction D2 and extends to the outside of the tip portions 5b and 6b in the first direction D1. The second region R2 has a rectangular frame shape when viewed from the third direction D3, and surrounds the rectangular first region R1 with a substantially uniform width.

As shown in FIG. 10, the transient voltage protection device 1F according to the sixth modification differs from the transient voltage protection device 1 (see FIG. ) are different. Here, the transient voltage protection device 1F will be described mainly with respect to the differences from the transient voltage protection device 1, and the description of the common points will be omitted as appropriate.

In the transient voltage protection device 1F, the internal electrodes 5 and 6 extend along the first direction D1, and are provided so that the tip portions 5b and 6b in the first direction D1 face each other in the first direction D1. . The tip portions 5b and 6b face each other with the gap region Sg interposed therebetween. The tip portions 5b and 6b face the gap region Sg. The internal electrodes 5 and 6 have a rectangular shape with the first direction D1 as the longitudinal direction in a plan view (that is, when viewed from the third direction D3). The internal electrodes 5 and 6 have, for example, the same shape. The internal electrodes 5 and 6 are provided substantially at the center of the element body 2 in the second direction D2.

The internal electrode 5 has a pair of corners 5g facing the internal electrode 6. As shown in FIG. The pair of corner portions 5g is a pair of corner portions on the tip portion 5b side among the four corner portions positioned at the four corners of the internal electrode 5 when viewed from the third direction D3. The pair of corners 5g are located at a pair of ends of the tip 5b in the second direction D2. The pair of corners 5g are provided at positions separated from the outer surface of the base body 2. As shown in FIG.

The internal electrode 6 has a pair of corners 6g facing the internal electrode 5. As shown in FIG. The pair of corner portions 6g is a pair of corner portions on the tip portion 6b side among the four corner portions positioned at the four corners of the internal electrode 6 when viewed from the third direction D3. The pair of corners 6g are located at a pair of ends of the tip 6b in the second direction D2. The pair of corners 6g are provided at positions separated from the outer surface of the base body 2. As shown in FIG.

The pair of corners 5g faces the pair of corners 6g in the first direction D1. One corner 5g and one corner 6g face each other in the first direction D1. The distance in the first direction D1 between one corner 5g and one corner 6g is equal to the shortest distance between the internal electrodes 5,6. The other corner 5g and the other corner 6g face each other in the first direction D1. The distance in the first direction D1 between the other corner 5g and the other corner 6g is equal to the shortest distance between the internal electrodes 5,6.

The auxiliary discharge portion 7 has a rectangular shape with the second direction D2 as its longitudinal direction in a plan view. The discharge auxiliary portion 7 is in contact with the internal electrodes 5 and 6 and connects the internal electrodes 5 and 6 to each other. The discharge auxiliary portion 7 extends to the outside of the internal electrodes 5 and 6 in the second direction D2. The auxiliary discharge portion 7 has a portion exposed from the internal electrodes 5 and 6 and facing the gap region Sg.

The first region R1 is located between a pair of second regions R2 separated from each other in the second direction D2, and connects the pair of second regions R2 in the second direction D2. The pair of second regions R2 are arranged on both sides of the first region R1 in the second direction D2 so as to sandwich the first region R1 in the second direction D2. In the first direction D1, the positions of both ends of the first region R1 match the positions of both ends of the second region R2.

The first region R1 is spaced apart from the pair of corners 5g and 6g, and is in contact with the center portion of the tip portion 5b in the second direction D2 and the center portion of the tip portion 6b in the second direction D2. is provided. The central portion of the tip portion 5b in the second direction D2 is the portion between the pair of corner portions 5g. The central portion of the tip portion 6b in the second direction D2 is the portion between the pair of corner portions 6g. The first region R1 connects the center portion of the tip portion 5b in the second direction D2 and the center portion of the tip portion 6b in the second direction D2 in the first direction D1. When viewed from the third direction D3, the first region R1 overlaps the center portion of the tip portion 5b in the second direction D2 and the center portion of the tip portion 6b in the second direction D2.

The second region R2 is provided so as to contact the pair of corners 5g and the pair of corners 6g. One second region R2 is in contact with one corner 5g and one corner 6g, and connects one corner 5g and one corner 6g in the first direction D1. The other second region R2 is in contact with the other corner 5g and the other corner 6g, and connects the other corner 5g and the other corner 6g in the first direction D1.

The hollow portion S is located inside the outer edge of the auxiliary discharge portion 7 when viewed from the third direction D3. The hollow portion S overlaps the first region R1 and the pair of second regions R2 when viewed from the third direction D3. The hollow portion S overlaps the entire tip portions 5b and 6b when viewed from the third direction D3. The width of the gap region Sg (the length of the gap region Sg in the first direction D1), that is, the interval between the internal electrodes 5 and 6 is, for example, 10 μm or more and 70 μm or less.

In transient voltage protection devices 1, 1A, 1B, 1C, 1D, 1E, and 1F, internal electrodes 5 and 6 have the same shape, but may have different shapes. Although the internal electrodes 5 and 6 extend entirely along the first direction D1, they may, for example, include portions that are curved or bent and do not extend along the first direction D1. In transient voltage protection devices 1, 1A, 1B, 1C, 1D, 1E, internal electrodes 5, 6 may have two or more corners 5g, 6g.

In the transient voltage protection device 1F, the internal electrodes 5, 6 may have different lengths in the second direction D2. For example, the tip portion 5b may be longer than the tip portion 6b in the second direction D2, and both ends of the tip portion 5b in the second direction D2 may not face the tip portion 6b in the first direction D1. In this case, since the internal electrode 5 does not have a corner facing the internal electrode 6, the second region R2 may be in contact with only the pair of corners 6g of the internal electrode 6. Also, for example, one end in the second direction D2 of the tip portion 5b may face the tip portion 6b in the first direction D1, and the other end may not face the tip portion 6b in the first direction D1. . In this case, since the internal electrode 5 has only one corner 5g facing the internal electrode 6, the second region R2 consists of a pair of corners 6g of the internal electrode 6 and one corner of the internal electrode 5. May be in contact with 5g only.

The transient voltage protection devices 1, 1A, 1B, 1C, 1D, 1E, 1F may not have the cavity S. The auxiliary discharge portion 7 may have at least two or more regions with mutually different metal densities, and the number of regions is not limited. The internal electrodes 5 and 6, the discharge auxiliary portion 7, and the hollow portion S are provided substantially in the center in the stacking direction (third direction D3), but are provided on the side 2c side or side 2d side from the center in the stacking direction. may be

The above embodiments and modifications may be combined as appropriate.

1, 1A, 1B, 1C, 1D, 1E, 1F... transient voltage protection device, 2... element body, 3, 4... external electrode, 5, 6... internal electrode, 5b, 6b... tip, 5c, 5d, 6c , 6d... side edges, 5g, 6g... corners, 7... discharge auxiliary parts, R1... first region, R2... second region, D1... first direction, D2... second direction, S... cavity, Sg … the gap region.

Claims (6)

body and
a first internal electrode and a second internal electrode provided in the element body spaced apart from each other;
a first external electrode connected to the first internal electrode;
a second external electrode connected to the second internal electrode;
a discharge auxiliary part that contains a metal and is provided in the element body so as to be in contact with the first internal electrode and the second internal electrode and to connect the first internal electrode and the second internal electrode to each other; prepared,
The discharge auxiliary part has at least a first region and a second region,
the metal concentration in the first region is higher than the metal concentration in the second region;
Transient voltage protection device. The first internal electrode has a first corner facing the second internal electrode,
The second internal electrode has a second corner facing the first internal electrode,
The second region is provided so as to be in contact with the first corner and the second corner,
The transient voltage protection device of claim 1. The first internal electrode and the second internal electrode each have a side edge extending along the first direction, and the side edges are opposed in a second direction intersecting the first direction. is designed to
The first region is provided so as to be spaced apart from the first corner and the second corner and in contact with the side edges of the first internal electrode and the second internal electrode, respectively.
A transient voltage protection device according to claim 2. The first internal electrode and the second internal electrode extend along the first direction, and are provided so that tip portions in the first direction face each other in the first direction,
The first region is provided so as to be spaced apart from the first corner and the second corner and to be in contact with the tip portions of the first internal electrode and the second internal electrode, respectively.
A transient voltage protection device according to claim 2. further comprising a cavity provided in the base body,
The first internal electrode and the second internal electrode face the cavity,
A transient voltage protection device according to any one of claims 1-4. the cavity includes a gap region positioned between the first internal electrode and the second internal electrode;
A transient voltage protection device according to claim 5.

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