Transient voltage protection device

Abstract

To provide a transient voltage protection device capable of reducing a clamp voltage and extending the life.SOLUTION: A transient voltage protection device 1 includes a base body 2 having end faces 2a and 2b facing each other in a first direction D1, an external electrode 3 arranged on the end surface 2a, an external electrode 4 arranged on the end face 2b, an internal electrode 5 including a connection end 5a connected to the external electrode 3, a tip portion 5b arranged inside the base body 2, and a side edge 5c extending from the tip portion 5b, and an internal electrode 6 including a connection end 6a connected to the external electrode 4, a tip portion 6b arranged in the base body 2, and a side edge 6d extending from the tip portion 6b, and the side edge 5c and the side edge 6d face each other in the fourth direction. Each of the tip portions 5b and 6b has a tapered shape when viewed from the second direction. The tip portion 5b faces the side edge 6d in the first direction D1. The tip portion 6b faces the side edge 5c in the first direction D1.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a transient voltage protection device.

Background Art

[0002] Patent Document 1 describes an ESD (Electro-Static Discharge) protection device including a magnetic base material, a pair of external electrodes, and a pair of opposing electrodes. In this ESD protection device, since the pair of opposing electrodes are arranged with their tip portions facing each other, discharge can be generated between the tip portions.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] One aspect of the present disclosure provides a transient voltage protection device capable of reducing the clamp voltage and extending the service life.

Means for Solving the Problems

[0005] A transient voltage protection device according to one aspect of the present disclosure includes a body having a first end face and a second end face facing each other in a first direction, a first external electrode disposed on the first end face, a second external electrode disposed on the second end face, a first connection end connected to the first external electrode, a first tip portion disposed inside the body, and a first side edge extending from the first tip portion. The first internal electrode has a second connection end connected to the second external electrode, a second tip portion disposed inside the body, and a second side edge extending from the second tip portion. The first side edge and the second side edge face each other in a second direction intersecting the first direction. Each of the first tip portion and the second tip portion has a tapered shape when viewed from a third direction orthogonal to each of the first direction and the second direction. The first tip portion faces the second side edge in the first direction, and the second tip portion faces the first side edge in the first direction.

[0006] In the transient voltage protection device according to the above aspect, the first side edge of the first internal electrode and the second side edge of the second internal electrode face each other. Thereby, discharge can be generated between the first side edge and the second side edge. Each of the first tip portion of the first internal electrode and the second tip portion of the second internal electrode has a tapered shape. Thereby, the electric field is concentrated at the first tip portion and the second tip portion. Therefore, the clamp voltage can be reduced. Even if the first tip portion and the second tip portion are deteriorated due to the electric field concentration, the discharge distance between the first side edge and the second side edge can be kept constant, so the discharge characteristics are maintained. Therefore, the service life can be extended. Since the first tip portion faces the second side edge of the second internal electrode, deterioration of the first tip portion is suppressed as compared with the case where it faces the corner portion of the second internal electrode. Since the second tip portion faces the first side edge of the first internal electrode, deterioration of the second tip portion is suppressed as compared with the case where it faces the corner portion of the first internal electrode.

[0007] A transient voltage protection device according to another aspect of the present disclosure includes a body having a first end face and a second end face facing each other in a first direction, a first external electrode disposed on the first end face, a second external electrode disposed on the second end face, a first connection end connected to the first external electrode, a first tip portion disposed inside the body, and a first side edge extending from the first tip portion. A first internal electrode, a second connection end connected to the second external electrode, a second tip portion disposed inside the body, and a second side edge extending from the second tip portion. A second internal electrode, wherein the first side edge and the second side edge face each other in a second direction intersecting the first direction, and each of the first tip portion and the second tip portion has a tapered shape when viewed from a third direction orthogonal to each of the first direction and the second direction. A cavity is formed inside the body, and each of the first tip portion and the second tip portion is disposed inside the cavity and faces the inner surface of the body defining the cavity in the first direction.

[0008] In the transient voltage protection device according to the above another aspect, the first side edge of the first internal electrode and the second side edge of the second internal electrode face each other. Thereby, discharge can be generated between the first side edge and the second side edge. Each of the first tip portion of the first internal electrode and the second tip portion of the second internal electrode has a tapered shape. Thereby, the electric field is concentrated at the first tip portion and the second tip portion. Therefore, the clamp voltage can be reduced. Each of the first tip portion and the second tip portion is disposed inside the cavity. Thereby, the discharge at the first tip portion and the second tip portion is promoted, so that the clamp voltage can be further reduced. Even if the first tip portion and the second tip portion are deteriorated due to the electric field concentration, the discharge distance between the first side edge and the second side edge can be kept constant, so that the discharge characteristics are maintained. Therefore, the service life can be extended. Each of the first tip portion and the second tip portion faces the inner surface of the body defining the cavity in the first direction. The first tip portion does not face the second internal electrode in the first direction inside the cavity. The second tip portion does not face the first internal electrode in the first direction inside the cavity. Thereby, the discharge location can be controlled, so that the discharge is stabilized. Also from this, the service life can be extended.

[0009] In the transient voltage protection device according to the above-described one aspect, a cavity is formed inside the element body, and each of the first tip portion and the second tip portion may be exposed to the cavity. In this case, discharge is promoted, and further reduction of the clamp voltage can be achieved.

[0010] The first side edge and the second side edge may be exposed to the cavity. In this case, since discharge at the first side edge and the second side edge is promoted, the discharge characteristics can be improved.

[0011] When viewed from the third direction, each of the first tip portion and the second tip portion may have an acute-angled shape. In this case, since electric field concentration at the first tip portion and the second tip portion is promoted, the clamp voltage can be surely reduced.

[0012] When viewed from the third direction, each of the first internal electrode and the second internal electrode may have a triangular shape. In this case, the first tip portion and the second tip portion can be easily tapered.

[0013] The transient voltage protection device may further include a discharge assisting portion in contact with each of the first tip portion and the second tip portion. In this case, since discharge at the first tip portion and the second tip portion is promoted, further reduction of the clamp voltage can be achieved.

[0014] The discharge assisting portion may be arranged so as to connect the first side edge and the second side edge to each other. In this case, since discharge at the first side edge and the second side edge is promoted, the discharge characteristics can be improved.

[0015] When viewed from the third direction, each of the first tip portion and the second tip portion may have a rounded shape. In this case, for example, the first tip portion and the second tip portion can be stably formed by printing, so the discharge characteristics are stabilized.

[0016] In the transient voltage protection device according to the above-described another aspect, the first tip portion may face the second side edge in the first direction, and the second tip portion may face the first side edge in the first direction. In this case, since the first tip portion faces the second side edge of the second internal electrode, deterioration of the first tip portion is suppressed as compared with the case where it faces the corner portion of the second internal electrode. Since the second tip portion faces the first side edge of the first internal electrode, deterioration of the second tip portion is suppressed as compared with the case where it faces the corner portion of the first internal electrode.

[0017] The distance in the second direction between the first side edge and the second side edge may be shorter than the distance in the first direction between the first tip portion and the second side edge, and may also be shorter than the distance in the first direction between the second tip portion and the first side edge. In this case, discharge preferentially occurs between the first side edge and the second side edge.

Advantages of the Invention

[0018] According to the present disclosure, it is possible to reduce the clamp voltage and extend the service life.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals will be used for the same elements or elements having the same function, and overlapping descriptions will be omitted.

[0021] The transient voltage protection device 1 according to the present embodiment shown in FIGS. 1 to 5 is an electronic component that is mounted on an electronic device (not shown) and protects the electronic device from transient voltages such as ESD. The electronic device protected by the transient voltage protection device 1 includes, for example, a circuit board or an electronic component. The transient voltage protection device 1 includes a body 2, a pair of external electrodes 3 and 4, a pair of internal electrodes 5 and 6, and a discharge assisting portion 7. The internal electrodes 5 and 6 are discharge electrodes configured to discharge. The internal electrodes 5 and 6, together with the discharge assisting portion 7, constitute a transient voltage suppressor. The transient voltage suppressor has transient voltage absorption performance.

[0022] The body 2 has a rectangular parallelepiped shape. The rectangular parallelepiped shape includes, for example, the shape of a rectangular parallelepiped with chamfered corners and edges, and the shape of a rectangular parallelepiped with rounded corners and edges. The 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. The four side faces 2c, 2d, 2e, and 2f are adjacent to the end faces 2a and 2b, respectively, and extend in the facing direction of the end faces 2a and 2b so as to connect the end faces 2a and 2b. One of the four side faces 2c, 2d, 2e, and 2f is defined as a mounting surface facing the electronic device to be protected.

[0023] In the present embodiment, the facing direction of the end faces 2a and 2b is defined as the first direction D1, the facing direction of the side faces 2c and 2d is defined as the second direction D2, and the facing direction of the side faces 2e and 2f is defined as the third direction D3. The first direction D1 is the length direction of the body 2, the second direction D2 is the height direction of the body 2, and the third direction D3 is the width direction of the body 2. The length of the body 2 (the length of the body 2 in the first direction D1) is, for example, 0.4 mm or more and 2.0 mm or less. The height of the body 2 (the length of the body 2 in the second direction D2) is, for example, 0.2 mm or more and 1.2 mm or less. The width of the body 2 (the length of the body 2 in the third direction D3) is, for example, 0.2 mm or more and 1.2 mm or less. In the present embodiment, the length of the body 2 is 1.6 mm, the height of the body 2 is 0.4 mm, and the width of the body 2 is 0.8 mm.

[0024] A cavity S is formed inside the element body 2. The cavity S is formed away from the outer surface of the element body 2. The cavity S is formed in approximately the center of the element body 2 in each of the first direction D1, the second direction D2, and the third direction D3. The element body 2 has an inner surface 2g that defines the cavity S. The inner surface 2g is exposed to the cavity S.

[0025] The cavity S has a rectangular shape in a plan view (i.e., when viewed from the second direction D2). The length of the cavity S (the length of the cavity S in the first direction D1) is, for example, 0.01 mm or more and less than 2.0 mm. The height of the cavity S (the length of the cavity S in the second direction D2) is, for example, 5 μm or more and 50 μm or less. The width of the cavity S (the length of the cavity S in the third direction D3) is, for example, 0.01 mm or more and less than 1.2 mm. In this embodiment, the length of the cavity S is 0.3 mm, the height of the cavity S is 30 μm, and the width of the cavity S is 0.21 mm.

[0026] The cavity S is formed, for example, by firing an organic lacquer applied onto the insulator green sheet together with the insulator green sheet. The cavity S is formed by burning off the organic lacquer. The organic lacquer includes an organic solvent and an organic binder. The organic lacquer is applied onto the insulator green sheet by, for example, printing.

[0027] As shown in FIG. 2, the element body 2 has a plurality of insulator layers 10 stacked in the second direction D2. In this embodiment, the element body 2 is configured by stacking a plurality of insulator layers 10. Each insulator layer 10 has a rectangular plate shape. Each insulator layer 10 is an insulator having electrical insulation properties, and is configured from a sintered body of an insulator green sheet. In the actual element body 2, each insulator layer 10 is integrated to the extent that the boundaries between them are not visible.

[0028] The insulator layer 10 is composed of ceramic materials such as Fe2O3, NiO, CuO, ZnO, MgO, SiO2, TiO2, MnCO3, SrCO3, CaCO3, BaCO3, Al2O3, ZrO2, and B2O3. The insulator layer 10 may be composed of a single ceramic material or may be composed by mixing two or more types of ceramic materials. The insulator layer 10 may contain glass. The insulator layer 10 may contain copper oxide (CuO, Cu2O) in order to enable low-temperature sintering.

[0029] As shown in FIGS. 1 and 3, the external electrodes 3 and 4 are provided on the outer surface of the 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 at both ends of the element body 2 in the first direction D1. The external electrodes 3 and 4 are spaced apart from each other in the first direction D1. In FIG. 2, the illustration of the external electrodes 3 and 4 is omitted.

[0030] The external electrode 3 is arranged on the end face 2a and is connected to the internal electrode 5. The external electrode 3 is formed so as to cover the end face 2a and a part of it wraps around onto the side faces 2c, 2d, 2e, 2f. The external electrode 3 is provided on the entire end face 2a and the end portions of the side faces 2c, 2d, 2e, 2f on the end face 2a side.

[0031] The external electrode 4 is provided on the end face 2b and is connected to the internal electrode 6. The external electrode 4 is formed so as to cover the end face 2b and a part of it wraps around onto the side faces 2c, 2d, 2e, 2f. The external electrode 4 is provided on the entire end face 2b and the end portions of the side faces 2c, 2d, 2e, 2f on the end face 2b side.

[0032] As shown in FIGS. 2 to 4, the internal electrodes 5 and 6 are provided in the element body 2 so as to be spaced apart from each other. The internal electrodes 5 and 6 extend along the first direction D1. The internal electrodes 5 and 6 are arranged at the same height position (i.e., the same stacking position) in the second direction D2. 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 at the center in the stacking direction (second direction D2).

[0033] The internal electrodes 5 and 6 have the same shape as each other in plan view (when viewed from the second direction D2). In the present embodiment, the internal electrodes 5 and 6 have a triangular shape in plan view. More specifically, the internal electrodes 5 and 6 have an isosceles triangular shape in plan view. The internal electrodes 5 and 6 are provided substantially at the center of the element body 2 in the third direction D3. When viewed from the first direction D1, at least a part of the internal electrodes 5 and 6 overlap each other.

[0034] The internal electrode 5 has a connection end 5a, a tip end 5b, side edges 5c and 5d, a main surface 5e, and a main surface 5f. When the internal electrode 5 is viewed in plan view, the connection end 5a, the side edges 5c, and the side edges 5d are portions forming the respective sides of the triangle. More specifically, the connection end 5a is a portion forming the base of the isosceles triangle, and the side edges 5c and 5d are portions forming the equal sides of the isosceles triangle. When viewed from the second direction D2, the side edges 5c and 5d have the same length as each other. The tip end 5b is a portion forming one corner of the triangle, and more specifically, is a portion forming the apex of the isosceles triangle.

[0035] The connection end 5a is exposed on the end face 2a and extends in the third direction D3. The connection end 5a is connected to the external electrode 3. The tip end 5b is disposed inside the element body 2. When viewed from the first direction D1, the tip end 5b overlaps the connection end 5a. The tip end 5b is spaced apart from the end face 2b. The tip end 5b faces the connection end 5a in the first direction D1. The tip end 5b connects the side edges 5c and 5d to each other. The tip end 5b is disposed inside the cavity S. The tip end 5b is exposed to the cavity S. The tip end 5b faces the inner surface 2g in the first direction D1. The tip end 5b does not face the internal electrode 6 in the first direction D1 inside the cavity S.

[0036] When viewed from the second direction D2, the tip portion 5b has a tapered shape. When viewed from the second direction D2, the tip portion 5b has a pointed shape. When viewed from the second direction D2, the tip portion 5b has an acute-angled shape. That is, when viewed from the second direction D2, the side edges 5c and 5d form an acute angle (less than 90 degrees). When viewed from the second direction D2, the tip portion 5b may actually have a rounded shape as shown in FIG. 4. The tip portion 5b may be formed into a pre-rounded shape during manufacturing. In this case, since the tip portion 5b can be stably formed by printing or the like, the discharge characteristics are stabilized. Also, since a change in the shape of the tip portion 5b due to discharge is less likely to occur, the discharge characteristics are further stabilized. Further, since melting of the tip due to discharge and scattering of the metal component inside the cavity S are suppressed, the occurrence of a short circuit is suppressed.

[0037] As shown in FIG. 3, the side edge 5c is connected to the connection end 5a and one end of the tip portion 5b in the third direction D3. The side edge 5c connects the connection end 5a and one end of the tip portion 5b in the third direction D3. The side edge 5c extends from the tip portion 5b and reaches one end of the tip portion 5b in the third direction D3. The side edge 5c faces the side surface 2e in the third direction D3. The side edge 5c has a portion exposed to the cavity S. The portion of the side edge 5c near the tip portion 5b is exposed to the cavity S.

[0038] The side edge 5d is connected to the connection end 5a and the other end of the tip portion 5b in the third direction D3. The side edge 5d connects the connection end 5a and the other end of the tip portion 5b in the third direction D3. The side edge 5d extends from the tip portion 5b and reaches the other end of the tip portion 5b in the third direction D3. The side edge 5d faces the side surface 2f in the third direction D3. The side edge 5d has a portion exposed to the cavity S. The portion of the side edge 5d near the tip portion 5b is exposed to the cavity S.

[0039] The main surfaces 5e and 5f face each other in the second direction D2. The main surface 5e faces the side surface 2c (see FIG. 1) in the second direction D2. The main surface 5f faces the side surface 2d (see FIG. 1) in the second direction D2. The main surface 5f includes a portion exposed to the cavity S. Each of the main surfaces 5e and 5f is adjacent to each of the connection end 5a, the side edge 5c, and the side edge 5d.

[0040] The internal electrode 6 has a connection end 6a, a tip portion 6b, a side edge 6c, a side edge 6d, a main surface 6e, and a main surface 6f. When the internal electrode 6 is viewed in plan view, the connection end 6a, the side edge 6c, and the side edge 6d are portions forming the respective sides of a triangle. More specifically, the connection end 6a is a portion forming the base of an isosceles triangle, and the side edges 6c and 6d are portions forming the equal sides of the isosceles triangle. When viewed from the second direction D2, the side edges 6c and 6d have the same length as each other. The tip portion 6b is a portion forming one corner of the triangle, and more specifically, is a portion forming the apex of the isosceles triangle.

[0041] The connection end 6a is exposed on the end face 2b and extends in the third direction D3. The connection end 6a is connected to the external electrode 4. The tip portion 6b is disposed inside the element body 2. The tip portion 6b overlaps the connection end 6a when viewed from the first direction D1. The tip portion 6b is spaced apart from the end face 2a. The tip portion 6b faces the connection end 6a in the first direction D1. The tip portion 6b connects the side edges 6c and 6d to each other. The tip portion 6b is disposed inside the cavity S. The tip portion 6b is exposed to the cavity S. The tip portion 6b faces the inner surface 2g in the first direction D1. The tip portion 6b does not face the internal electrode 5 in the first direction D1 inside the cavity S.

[0042] When viewed from the second direction D2, the tip portion 6b has a tapered shape. When viewed from the second direction D2, the tip portion 6b has a pointed shape. When viewed from the second direction D2, the tip portion 6b has an acute-angled shape. That is, when viewed from the second direction D2, the side edges 6c and 6d form an acute angle. When viewed from the second direction D2, the tip portion 6b may actually have a rounded shape as shown in FIG. 4. The tip portion 6b may be formed into a pre-rounded shape during manufacturing. In this case, since the tip portion 6b can be stably formed by printing or the like, the discharge characteristics are stabilized. Also, since a change in the shape of the tip portion 6b due to discharge is less likely to occur, the discharge characteristics are further stabilized. Further, since melting of the tip due to discharge and scattering of the metal component inside the cavity S are suppressed, the occurrence of a short circuit is suppressed.

[0043] The side edge 6c is connected to the connection end 6a and one end of the tip portion 6b in the third direction D3. The side edge 6c connects the connection end 6a and one end of the tip portion 6b in the third direction D3. The side edge 6c extends from the tip portion 6b and reaches one end of the tip portion 6b in the third direction D3. The side edge 6c faces the side surface 2e in the third direction D3. The side edge 6c has a portion exposed to the cavity S. The portion of the side edge 6c closer to the tip portion 6b is exposed to the cavity S.

[0044] The side edge 6d is connected to the connection end 6a and the other end of the tip portion 6b in the third direction D3. The side edge 6d connects the connection end 6a and the other end of the tip portion 6b in the third direction D3. The side edge 6d extends from the tip portion 6b and reaches the other end of the tip portion 6b in the third direction D3. The side edge 6d faces the side surface 2f in the third direction D3. The side edge 6d has a portion exposed to the cavity S. The portion of the side edge 6d closer to the tip portion 6b is exposed to the cavity S.

[0045] The main surfaces 6e and 6f face each other in the second direction D2. The main surface 6e faces the side surface 2c (see FIG. 1) in the second direction D2. The main surface 6f faces the side surface 2d (see FIG. 1) in the second direction D2. The main surface 6f includes a portion exposed to the cavity S. Each of the main surfaces 6e and 6f is adjacent to each of the connection end 6a, the side edge 6c, and the side edge 6d.

[0046] The side edge 5c and the side edge 6d face each other in the fourth direction D4. The fourth direction D4 intersects the first direction D1 and is orthogonal to the second direction D2. The fourth direction D4 is orthogonal to the side edge 5c and the side edge 6d. In the present embodiment, the fourth direction D4 is inclined with respect to the third direction D3. The side edge 5c and the side edge 6d are arranged to be parallel to each other. The tip portion 5b faces the side edge 6d in the first direction D1 outside the cavity S. The tip portion 6b faces the side edge 5c in the first direction D1 outside the cavity S. When viewed from the first direction D1, the tip portion 5b overlaps the internal electrode 6, and the tip portion 6b overlaps the internal electrode 5. In the third direction D3, the tip portion 5b is arranged closer to the side surface 2f than the tip portion 6b.

[0047] The distance L1 in the fourth direction D4 between the side edge 5c and the side edge 6d is shorter than the distance L2 in the first direction D1 between the tip portion 5b and the side edge 6d and shorter than the distance L3 in the first direction D1 between the tip portion 6b and the side edge 5c. Thereby, discharge preferentially occurs between the side edge 5c and the side edge 6d. The distance L1 is, for example, 1 μm or more and 50 μm or less. The distances L2 and L3 are, for example, equal to each other, longer than 0.05 mm, and 0.5 mm or less. In the present embodiment, the distance L1 is 20 μm, and the distances L2 and L3 are 0.16 mm. The distances L2 and L3 may be twice or more the distance L1.

[0048] The lengths of the internal electrodes 5 and 6 (the maximum lengths of the internal electrodes 5 and 6 in the first direction D1) are longer than 1 / 2 of the length of the base body 2 in the first direction D1, and are, for example, 0.2 mm or more and 2.0 mm or less. The widths of the internal electrodes 5 and 6 (the maximum lengths of the internal electrodes 5 and 6 in the third direction D3) are the lengths of the connection ends 5a and 6a in the third direction D3, and are, for example, 0.05 mm or more and 1.2 mm or less. The thicknesses of the internal electrodes 5 and 6 (the lengths of the internal electrodes 5 and 6 in the second direction D2) are, for example, 3 μm or more and 20 μm or less. In the present embodiment, the length of the internal electrodes 5 and 6 is 0.8 mm, the width of the internal electrodes 5 and 6 is 0.21 mm, and the thickness of the internal electrodes 5 and 6 is 8.5 μm.

[0049] The external electrodes 3 and 4 and the internal electrodes 5 and 6 are made of, for example, a conductor material containing Ag, Pd, Au, Pt, Cu, Ni, Al, Mo, or W. The external electrodes 3 and 4 and the internal electrodes 5 and 6 may be made of, for example, an Ag / Pd alloy, an Ag / Cu alloy, an Ag / Au alloy, or an Ag / Pt alloy. The external electrodes 3 and 4 and the internal electrodes 5 and 6 may be made of the same material as each other, or may be made of different materials from each other.

[0050] The external electrodes 3 and 4 are formed, for example, by applying a conductor paste containing the above conductive material to the outer surface of the base body 2 and then baking the conductor paste. The external electrodes 3 and 4 may have a plating layer. The internal electrodes 5 and 6 are formed, for example, by applying a conductor paste containing the above conductive material onto an insulator green sheet by printing and then firing the conductor paste together with the insulator green sheet.

[0051] The discharge assisting portion 7 is disposed inside the base body 2 and is provided at a distance from the outer surface of the base body 2. The discharge assisting portion 7 is disposed inside the cavity S. The discharge assisting portion 7 is exposed in the cavity S. The discharge assisting portion 7 is in contact with the tip portions 5b and 6b. The discharge assisting portion 7 is in contact with portions of the main surfaces 5e and 6e near the tip portions 5b and 6b. The discharge assisting portion 7 is disposed so as to connect the side edges 5c and 6d to each other. When viewed from the second direction D2, the discharge assisting portion 7 overlaps the side edges 5c and 6d.

[0052] As shown in FIGS. 3 and 4, the discharge assisting portion 7 has a rectangular shape in plan view (i.e., when viewed from the second direction D2). When viewed from the second direction D2, the entire discharge assisting portion 7 overlaps with the cavity S. The length of the discharge assisting portion 7 (the length in the first direction D1 of the discharge assisting portion 7) is shorter than the length of the cavity S in the first direction D1, for example, 1 μm or more and less than 2.0 mm. The width of the discharge assisting portion 7 (the length in the third direction D3 of the discharge assisting portion 7) is shorter than the length of the cavity S in the first direction D1, for example, 1 μm or more and less than 1.2 mm. The thickness of the discharge assisting portion 7 (the length in the second direction D2 of the discharge assisting portion 7) is, for example, 1 μm or more and 20 μm or less. In the present embodiment, the length of the discharge assisting portion 7 is 0.26 mm, the width of the discharge assisting portion 7 is 0.19 mm, and the thickness of the discharge assisting portion 7 is 5 μm.

[0053] The discharge assisting portion 7 contains an insulator and metal particles. The insulator is composed of, for example, a ceramic material. Examples of the ceramic material include Fe2O3, NiO, CuO, ZnO, MgO, SiO2, TiO2, MnCO3, SrCO3, CaCO3, BaCO3, AL2O3, ZrO2, or B2O3. The discharge assisting portion 7 may contain only one type of these ceramic materials, or may contain a mixture of two or more types. The metal particles are composed of, for example, Ag, Pd, Au, Pt, an Ag / Pd alloy, an Ag / Cu alloy, an Ag / Au alloy, or an Ag / Pt alloy. The discharge assisting portion 7 may contain semiconductor particles such as RuO2. The discharge assisting portion 7 may contain glass.

[0054] The discharge assisting portion 7 is formed, for example, by applying a slurry containing the above ceramic material and metal particles onto an insulator green sheet by printing and then firing the slurry together with the insulator green sheet.

[0055] As described above, in the transient voltage protection device 1, the side edges 5c and 6d face each other. Thus, discharge can be generated between the side edge 5c and the side edge 6d. The tip portions 5b and 6b have a tapered shape. Thus, the electric field is concentrated on the tip portions 5b and 6b. Therefore, the clamp voltage can be reduced. The tip portions 5b and 6b are disposed inside the cavity S. Thus, the discharge at the tip portions 5b and 6b is promoted. Therefore, the clamp voltage can be further reduced.

[0056] In the transient voltage protection device 1, even if the tip portions 5b and 6b are melted, degenerated, and deteriorated due to the electric field concentration, the discharge distance between the side edge 5c and the side edge 6d can be kept constant. Thereby, since the discharge characteristics are maintained, the long life can be achieved. Since the tip portion 5b faces the side edge 6d in the first direction D1, compared with the case where it faces the corner portion of the internal electrode 6, the melting, degeneration, and deterioration of the tip portion 5b due to the electric field concentration are suppressed. Since the tip portion 6b faces the side edge 5c in the first direction D1, compared with the case where it faces the corner portion of the internal electrode 5, the melting, degeneration, and deterioration of the tip portion 6b due to the electric field concentration are suppressed. The tip portions 5b and 6b face the inner surface 2g. That is, the tip portion 5b does not face the internal electrode 6 in the first direction D1 inside the cavity S. The tip portion 6b does not face the internal electrode 5 in the first direction D1 inside the cavity S. Thereby, the discharge location can be controlled. Therefore, the discharge becomes stable. Also from this, the long life can be achieved.

[0057] The side edges 5c and 6d are exposed to the cavity S. For this reason, the discharge at the side edges 5c and 6d is promoted. Therefore, the discharge characteristics can be improved.

[0058] When viewed from the second direction D2, the tip portions 5b and 6b have an acute angle shape. For this reason, the electric field concentration at the tip portions 5b and 6b is promoted. Therefore, the clamp voltage can be surely reduced. When viewed from the second direction D2, the internal electrodes 5 and 6 have a triangular shape. For this reason, the tip portions 5b and 6b can be easily formed into a tapered shape.

[0059] The discharge assisting portion 7 is in contact with the tip portions 5b and 6b. Thereby, since the discharge at the tip portions 5b and 6b is promoted, further reduction of the clamping voltage can be achieved. The discharge assisting portion 7 is arranged so as to connect the side edges 5c and 6d to each other. For this reason, the discharge at the side edges 5c and 6d is promoted. Therefore, the discharge characteristics can be improved.

[0060] The present invention is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the gist thereof.

[0061] In the above embodiment, the discharge assisting portion 7 and the cavity S have the same shape in plan view, but they may have different shapes. The transient voltage protection device 1 may not include the discharge assisting portion 7. The internal electrode 5 only needs to have at least the connection end 5a, the tip portion 5b, and the side edge 5c, and may have a shape other than a triangular shape when viewed from the second direction D2. Further, the side edge 5c only needs to extend from the tip portion 5b and may not be connected to the connection end 5a. The internal electrode 6 only needs to have at least the connection end 6a, the tip portion 6b, and the side edge 6d, and may have a shape other than a triangular shape when viewed from the second direction D2. Further, the side edge 6c only needs to extend from the tip portion 6b and may not be connected to the connection end 6a.

Explanation of Reference Numerals

[0062] 1... Transient voltage protection device, 2... Element body, 2a, 2b... End faces, 2g... Inner face, 3, 4... External electrodes, 5, 6... Internal electrodes, 5a, 6a... Connection ends, 5b, 6b... Tip portions, 5c, 5d, 6c, 6d... Side edges, 7... Discharge assisting portion, S... Cavity.

Claims

1. an element body having a first end surface and a second end surface facing each other in a first direction; a first external electrode disposed on the first end surface; A second external electrode disposed on the second end surface; a first internal electrode having a first connection end connected to the first external electrode, a first tip portion disposed within the element body, and a first side edge extending from the first tip portion; a second internal electrode having a second connection end connected to the second external electrode, a second tip end disposed within the element body, and a second side edge extending from the second tip end; Equipped with the first side edge and the second side edge face each other in a second direction intersecting the first direction, Each of the first tip portion and the second tip portion has a tapered shape when viewed from a third direction perpendicular to each of the first direction and the second direction, The first tip portion faces the second side edge in the first direction, The second tip portion faces the first side edge in the first direction, When viewed from the third direction, each of the first internal electrode and the second internal electrode has a triangular shape. Transient voltage protection device.

2. an element body having a first end surface and a second end surface facing each other in a first direction; a first external electrode disposed on the first end surface; A second external electrode disposed on the second end surface; a first internal electrode having a first connection end connected to the first external electrode, a first tip portion disposed within the element body, and a first side edge extending from the first tip portion; a second internal electrode having a second connection end connected to the second external electrode, a second tip end disposed within the element body, and a second side edge extending from the second tip end; Equipped with the first side edge and the second side edge face each other in a second direction intersecting the first direction, Each of the first tip portion and the second tip portion has a tapered shape when viewed from a third direction orthogonal to each of the first direction and the second direction. A cavity is formed inside the element body. Each of the first tip portion and the second tip portion is disposed inside the cavity and faces the inner surface of the element body that defines the cavity in the first direction. When viewed from the third direction, each of the first internal electrode and the second internal electrode has a triangular shape. Transient voltage protection device.

3. An element body having a first end face and a second end face facing each other in a first direction, A first external electrode disposed on the first end face, A second external electrode disposed on the second end face, A first internal electrode having a first connection end connected to the first external electrode, a first tip portion disposed inside the element body, and a first side edge extending from the first tip portion, A second internal electrode having a second connection end connected to the second external electrode, a second tip portion disposed inside the element body, and a second side edge extending from the second tip portion, comprising The first side edge and the second side edge face each other in a second direction intersecting the first direction, Each of the first tip portion and the second tip portion has a tapered shape when viewed from a third direction orthogonal to each of the first direction and the second direction. The first tip portion faces the second side edge in the first direction, The second tip portion faces the first side edge in the first direction. When viewed from the third direction, each of the first tip portion and the second tip portion has a rounded shape. Transient voltage protection device.

4. An element body having a first end face and a second end face facing each other in a first direction, a first external electrode disposed on the first end surface; A second external electrode disposed on the second end surface; a first internal electrode having a first connection end connected to the first external electrode, a first tip portion disposed within the element body, and a first side edge extending from the first tip portion; a second internal electrode having a second connection end connected to the second external electrode, a second tip end disposed within the element body, and a second side edge extending from the second tip end; Equipped with the first side edge and the second side edge face each other in a second direction intersecting the first direction, Each of the first tip portion and the second tip portion has a tapered shape when viewed from a third direction perpendicular to each of the first direction and the second direction, A cavity is formed inside the body, each of the first tip portion and the second tip portion is disposed inside the cavity and faces an inner surface of the body defining the cavity in the first direction; When viewed from the third direction, each of the first tip portion and the second tip portion has a rounded shape. Transient voltage protection device.

5. an element body having a first end surface and a second end surface facing each other in a first direction; a first external electrode disposed on the first end surface; A second external electrode disposed on the second end surface; a first internal electrode having a first connection end connected to the first external electrode, a first tip portion disposed within the element body, and a first side edge extending from the first tip portion; a second internal electrode having a second connection end connected to the second external electrode, a second tip end disposed within the element body, and a second side edge extending from the second tip end; Equipped with the first side edge and the second side edge face each other in a second direction intersecting the first direction, Each of the first tip portion and the second tip portion has a tapered shape when viewed from a third direction orthogonal to each of the first direction and the second direction. A cavity is formed inside the element body. Each of the first tip portion and the second tip portion is disposed inside the cavity and directly faces the inner surface of the element body that defines the cavity in the first direction. Transient voltage protection device.

6. A cavity is formed inside the element body. Each of the first tip portion and the second tip portion is exposed to the cavity. The transient voltage protection device according to claim 1 or 3.

7. The first side edge and the second side edge are exposed to the cavity. The transient voltage protection device according to claim 2, 4, 5 or 6.

8. When viewed from the third direction, each of the first tip portion and the second tip portion has an acute-angled shape. The transient voltage protection device according to any one of claims 1 to 7.

9. Further provided with a discharge assisting portion in contact with each of the first tip portion and the second tip portion. The transient voltage protection device according to any one of claims 1 to 8.

10. The discharge assisting portion is disposed so as to connect the first side edge and the second side edge to each other. The transient voltage protection device according to claim 9.

11. The first tip portion faces the second side edge in the first direction. The second tip portion faces the first side edge in the first direction. The transient voltage protection device according to claim 2, 4 or 5.

12. The distance in the second direction between the first side edge and the second side edge is shorter than the distance in the first direction between the first tip and the second side edge, and shorter than the distance in the first direction between the second tip and the first side edge. The transient voltage protection device according to claim 1, 3 or 11.

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