Transient voltage protection device

Abstract

To provide a transient voltage protection device that reduces a variation in a clamp voltage.SOLUTION: A transient voltage protection device 1 includes an element body 2 formed with a cavity S inside, a pair of internal electrodes 5, 6, and a discharge assistance portion 7. The internal electrode 5 has an edge 5a, and the internal electrode 6 has an edge 6a. The pair of internal electrodes 5, 6 are disposed in the element body 2 such that a part 5a1 of the edge 5a and a part 6a1 of the edge 6a oppose each other in a first direction D1 in the cavity S. The discharge assistance portion 7 is disposed in the element body 2 so as to be in contact with the part 5a1 and the part 6a1. The edge 5a includes an end 5f including corners 5f4, 5f5. The edge 6a includes an end 6f including corners 6f4, 6f5. The discharge assistance portion 7 includes a pair of edges 7c, 7d which oppose each other in a second direction D2 and which are exposed into the cavity S. The part 5a1 does not include the corners 5f4, 5f5. The part 6a1 does not include the corners 6f4, 6f5.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] Known transient voltage protection devices include a body having a cavity formed therein, a pair of external electrodes disposed on the body, and a pair of internal electrodes and a discharge assisting portion disposed within the body (see, for example, Patent Document 1). Each of the pair of internal electrodes has an edge. A part of each edge faces each other within the cavity. The discharge assisting portion contacts the above-mentioned part of the edge that each of the pair of internal electrodes has.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a configuration where the length of the discharge assisting portion is greater than the length of the cavity in a direction intersecting the direction in which a part of the edge that each of the pair of internal electrodes has faces each other, there is a region where the discharge assisting portion is not exposed to the cavity between the parts of the edges facing each other. In this configuration, not only the region of the discharge assisting portion that is exposed to the cavity but also the above-mentioned region that is not exposed to the cavity may induce discharge. Discharge between the above-mentioned regions that are not exposed to the cavity does not occur through the cavity, so there is a risk that the clamp voltage is affected by the resistance value of the body. In this case, there is a risk that the clamp voltage varies.

[0005] Each aspect of the present invention aims to provide a transient voltage protection device that suppresses variations in the clamp voltage.

Means for Solving the Problems

[0006] A transient voltage protection device according to one embodiment comprises a body with a cavity formed inside, a pair of external electrodes disposed on the body, and a pair of internal electrodes and a discharge assist portion disposed inside the body. Each of the pair of internal electrodes has an edge. The pair of internal electrodes are disposed inside the body such that a portion of each edge faces each other in a first direction within the cavity. The discharge assist portion is disposed inside the body so as to be in contact with the portion of the edge of each of the pair of internal electrodes. Each of the edge of the pair of internal electrodes includes a first end and a second end. The first end is exposed on the outer surface of the body and is connected to the corresponding external electrode of the pair of external electrodes. The second end is located on the opposite side from the first end and includes a corner. The discharge assist portion has a pair of edges that face each other in a second direction intersecting the first direction and are exposed inside the cavity. The portion of the edge of each of the pair of internal electrodes does not include the corner.

[0007] In one of the above embodiments, the discharge assist portion has a pair of edges that face each other in the second direction and are exposed into the cavity. Therefore, in the second direction, the length of the discharge assist portion is less than the length of the cavity. Between the parts of the opposing edges, the discharge assist portion does not have a region that is not exposed into the cavity. As a result, this embodiment makes it difficult to generate a discharge that does not pass through the cavity. The aforementioned portion of the edges of each of the pair of internal electrodes faces each other within the cavity and does not include the corner of the second end. Therefore, the corner is not exposed to the cavity and does not come into contact with the discharge assist portion. As a result, this one embodiment ensures that a discharge occurs reliably in the region of the discharge assist portion that is exposed to the cavity. The region of the discharge assist portion that is exposed to the cavity is sometimes simply referred to as the "exposed region". Based on the above, the above embodiment suppresses variations in the clamp voltage.

[0008] In one of the above embodiments, the discharge assist portion may have another pair of edges that face each other in the first direction and are in contact with the corresponding internal electrodes of the pair of internal electrodes. The configuration in which the discharge assist section has the aforementioned pair of edges ensures that discharge occurs more reliably in the exposed area. Therefore, this configuration further suppresses variations in the clamp voltage.

[0009] In one of the above embodiments, the discharge assist portion may be curved in a cross-section along a third direction intersecting the first and second directions. The curved discharge assist section, as described above, easily increases the opposing surface area of ​​the pair of internal electrodes. Therefore, this configuration can suppress the deterioration of transient voltage protection characteristics.

[0010] In one of the above embodiments, the pair of internal electrodes may be curved in a cross-section along the third direction. The configuration in which the pair of internal electrodes are curved as described above easily increases the opposing surface area of ​​the pair of internal electrodes. Therefore, this configuration can suppress the deterioration of transient voltage protection characteristics.

[0011] In one of the above embodiments, the pair of internal electrodes may be curved in a cross-section along the third direction so as to follow the discharge assist portion. As described above, the configuration in which the pair of internal electrodes are curved to follow the discharge assist section makes it easier to further increase the opposing surface area of ​​the pair of internal electrodes. Therefore, this configuration can further suppress the deterioration of transient voltage protection characteristics.

[0012] In one of the above embodiments, the length of the discharge assist portion in the second direction between the portion of the edge of the pair of internal electrodes may be greater than the distance in the second direction between the pair of edge of the discharge assist portion and the two ends of the cavity in the second direction that correspond to each other. As described above, a configuration in which the length of the discharge assist section in the second direction is greater than the above-mentioned interval ensures that discharge occurs more reliably in the exposed area. Therefore, this configuration further suppresses variations in the clamp voltage.

[0013] Another embodiment of the transient voltage protection device comprises a body with a cavity formed inside, a pair of external electrodes disposed on the body, a pair of internal electrodes and a discharge assist portion disposed within the body. The device comprises a body with a cavity formed inside, a pair of external electrodes disposed on the body, a pair of internal electrodes disposed within the body so as to face each other in a first direction and exposed to the cavity, and a discharge assist portion disposed within the body so as to be in contact with the pair of internal electrodes. Each of the pair of internal electrodes has a first end and a second end. The first end is connected to the corresponding external electrode of the pair of external electrodes. The second end is located on the opposite side from the first end and includes a corner. The discharge assist portion has a pair of edges that face each other in a second direction intersecting the first direction. The pair of edges are located inside the cavity when viewed from a third direction intersecting the first and second directions. The corner is not exposed to the cavity and is not in contact with the discharge assist portion.

[0014] In one of the other embodiments described above, the pair of edges of the discharge assist portion are located inside the cavity when viewed from a third direction. Therefore, in the second direction, the length of the discharge assist portion is less than the length of the cavity. Between the pair of opposing internal electrodes, the discharge assist portion has no region that is not exposed to the cavity. As a result, this embodiment makes it difficult to generate a discharge that does not pass through the cavity. The corner portion included in the second end is neither exposed to the cavity nor in contact with the discharge assist portion. Therefore, this one embodiment ensures that a discharge occurs reliably in the region exposed to the cavity of the discharge assist portion. Based on the above, the other embodiment described above suppresses variations in the clamp voltage. [Effects of the Invention]

[0015] Each aspect of the present invention provides a transient voltage protection device that suppresses variations in clamp voltage. [Brief explanation of the drawing]

[0016] [Figure 1] FIG. 1 is a perspective view showing a transient voltage protection device according to an embodiment. [Figure 2] FIG. 2 is an exploded perspective view showing the structure of the body. [Figure 3] FIG. 3 is a diagram showing a pair of internal electrodes and a discharge assisting portion. [Figure 4] FIG.  4 is a diagram showing a cross-sectional structure along line IV-IV of FIG. 1. [Figure 5] FIG. 5 is a diagram showing a cross-sectional structure along line V-V of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention 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 redundant descriptions will be omitted.

[0018] Referring to FIGS. 1 to 5, the configuration of the transient voltage protection device 1 according to the present embodiment will be described. FIG. 1 is a perspective view showing the transient voltage protection device according to the present embodiment. FIG. 2 is an exploded perspective view showing the structure of the body. FIG. 3 is a diagram showing a pair of internal electrodes and a discharge assisting portion. FIG. 4 is a diagram showing a cross-sectional structure along line IV-IV of FIG. 1. FIG. 5 is a diagram showing a cross-sectional structure along line V-V of FIG. 1.

[0019] As shown in FIGS. 1 and 2, 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 transient voltage protection device 1 is mounted on an electronic device (not shown). The transient voltage protection device 1 protects the electronic device from transient voltages. The electronic device protected by the transient voltage protection device 1 includes, for example, a circuit board or electronic components. The transient voltage is caused by, for example, electrostatic discharge (ESD: Electro-Static Discharge).

[0020] 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. Body 2 has a pair of opposing end faces 2a, 2b, a pair of opposing side faces 2c, 2d, and a pair of opposing side faces 2e, 2f. In this embodiment, the pair of side faces 2e, 2f face each other in a first direction D1, the pair of end faces 2a, 2b face each other in a second direction D2, and the pair of side faces 2c, 2d face each other in a third direction D3. The pair of end faces 2a, 2b and the four side faces 2c, 2d, 2e, 2f constitute the outer surface of Body 2. The four side faces 2c, 2d, 2e, 2f are adjacent to end faces 2a and 2b, respectively, and extend in a second direction D2 to connect end faces 2a and 2b. One of the four sides 2c, 2d, 2e, and 2f is defined as the mounting side facing the electronic device on which the transient voltage protection device 1 is mounted.

[0021] As shown in Figure 2, the base body 2 is constructed by stacking multiple insulating layers 20 in a third direction D3. The base body 2 has multiple stacked insulating layers 20. In the base body 2, each insulating layer 20 is integrated to such an extent that the boundaries between each insulating layer 20 are not visible. Each insulating layer 20 is constructed, for example, as a sintered body of a ceramic green sheet containing an insulating material.

[0022] The insulating material includes, for example, a ceramic material. The ceramic material is selected from the group consisting of, for example, Fe2O3, NiO, CuO, ZnO, MgO, SiO2, TiO2, MnCO3, SrCO3, CaCO3, BaCO3, Al2O3, ZrO2, and B2O3. The insulating layer 20 may consist of a single ceramic material or of two or more types of ceramic materials. The insulating layer 20 may contain glass. The insulating layer 20 may contain copper oxide (CuO or Cu2O) to enable low-temperature sintering.

[0023] The first direction D1 is the width direction of the base body 2, the second direction D2 is the length direction of the base body 2, and the third direction D3 is the height direction of the base body 2. The width of the base body 2 is, for example, 0.3 mm or more and 1.2 mm or less. The length of the base body 2 is, for example, 0.6 mm or more and 2.0 mm or less. The height of the base body 2 is, for example, 0.2 mm or more and 1.2 mm or less. In this embodiment, the width of the base body 2 is 1.0 mm, the length of the base body 2 is 0.5 mm, and the height of the base body 2 is 0.5 mm.

[0024] External electrodes 3 and 4 are positioned on the base body 2. External electrodes 3 and 4 are positioned on the base body 2 so as to face each other in the second direction D2. External electrodes 3 and 4 are positioned at both ends of the base body 2 in the second direction D2. External electrodes 3 and 4 are spaced apart from each other in the second direction D2.

[0025] The external electrode 3 is positioned on the end face 2a. The external electrode 3 is connected to the internal electrode 5. The external electrode 3 is physically and electrically connected to the internal electrode 5. The external electrode 3 covers the end face 2a. The external electrode 3 also covers parts of each of the four sides 2c, 2d, 2e, and 2f. The parts of the four sides 2c, 2d, 2e, and 2f that are covered by the external electrode 3 are located closer to the end face 2a on the corresponding side 2c, 2d, 2e, and 2f. The external electrode 3 is positioned on the entire surface of the end face 2a and on the ends of the sides 2c, 2d, 2e, and 2f that are closer to the end face 2a.

[0026] The external electrode 4 is positioned on the end face 2b. The external electrode 4 is connected to the internal electrode 6. The external electrode 4 is physically and electrically connected to the internal electrode 6. The external electrode 4 covers the end face 2b. The external electrode 4 also covers parts of each of the four sides 2c, 2d, 2e, and 2f. The parts of the four sides 2c, 2d, 2e, and 2f that are covered by the external electrode 4 are located closer to the end face 2b on the corresponding side 2c, 2d, 2e, and 2f. The external electrode 4 is positioned on the entire surface of the end face 2b and on the ends of the sides 2c, 2d, 2e, and 2f that are closer to the end face 2b.

[0027] The internal electrodes 5 and 6 are arranged within the substrate 2 so as to face each other in the first direction D1. Each internal electrode 5 and 6 extends in the second direction D2. Internal electrode 5 is positioned closer to side surface 2e. Internal electrode 6 is positioned closer to side surface 2f. In the third direction D3, internal electrodes 5 and 6 are positioned at the same height, i.e., at the same stacking position. As shown in Figure 2, internal electrodes 5 and 6 are positioned on the same insulating layer 20. Internal electrodes 5 and 6 are positioned approximately in the center of the stacking direction of the insulating layer 20 in the third direction D3.

[0028] As shown in Figure 3, the internal electrode 5 has a pair of opposing edges 5a, 5b and a pair of opposing faces 5c, 5d. The pair of edges 5a, 5b face each other in a first direction D1, and the pair of faces 5c, 5d face each other in a third direction D3. In this embodiment, edge 5a includes a pair of ends 5e, 5f. In addition to the pair of edges 5a, 5b and the pair of faces 5c, 5d, the internal electrode 5 has a pair of ends 5e, 5f. Edge 5a faces the internal electrode 6. Each edge 5a, 5b is adjacent to each of the faces 5c and 5d, respectively.

[0029] End 5e is exposed on the outer surface of the base body 2. End 5e is exposed on the end face 2a. End 5e is connected to the external electrode 3. In this embodiment, end 5e is directly connected to the external electrode 3. End 5e constitutes a connecting end that is connected to the external electrode 3. End 5e includes not only one end of the internal electrode 5, but also a region from one end of the internal electrode 5 up to a predetermined length. Therefore, end 5e has the predetermined length in the second direction D2.

[0030] In this embodiment, the end 5e includes a surface 5e1 exposed to the end face 2a, a portion 5e2 located closer to the internal electrode 6 and extending in the second direction D2, and a portion 5e3 located on the opposite side of portion 5e2 and extending in the second direction D2. The edge 5a includes portion 5e2 of the end 5e. The end 5e includes a portion included in the edge 5a and a portion not included in the edge 5a.

[0031] End 5f is located opposite to end 5e in the second direction D2. End 5f is located inside the element 2 and is not exposed on the outer surface of the element 2. End 5f is spaced apart from each end face 2a, 2b. End 5f is embedded in the element 2 and is in contact only with the element 2. Viewed from the third direction D3, end 5f is spaced apart from the external electrode 4 and does not overlap with the external electrode 4. Similar to end 5e, end 5f also includes a region from the other end of the internal electrode 5 up to a predetermined length. Therefore, end 5f also has the predetermined length in the second direction D2.

[0032] In this embodiment, end 5f includes a surface 5f1 that constitutes the tip surface of the internal electrode 5, a portion 5f2 located closer to the internal electrode 6 and extending in the second direction D2, a portion 5f3 located on the opposite side of portion 5f2 and extending in the second direction D2, and corners 5f4 and 5f5. Corner 5f4 is located between surface 5f1 and portion 5f2. Surface 5f1 and portion 5f2 are adjacent to corner 5f4. Corner 5f5 is located between surface 5f1 and portion 5f3. Surface 5f1 and portion 5f3 are adjacent to corner 5f5. Edge 5a includes portion 5f2 of end 5f. End 5f includes a portion included in edge 5a and a portion not included in edge 5a. For example, if end 5e constitutes the first end, end 5f constitutes the second end.

[0033] As shown in Figure 3, the internal electrode 6 has a pair of opposing edges 6a, 6b and a pair of opposing surfaces 6c, 6d. The pair of edges 6a, 6b face each other in a first direction D1, and the pair of surfaces 6c, 6d face each other in a third direction D3. In this embodiment, edge 6a includes a pair of ends 6e, 6f. In addition to the pair of edges 6a, 6b and the pair of surfaces 6c, 6d, the internal electrode 6 has a pair of ends 6e, 6f. Edge 6a faces the internal electrode 5. Each edge 6a, 6b is adjacent to a surface 6c and a surface 6d, respectively.

[0034] End 6e is exposed on the outer surface of the base body 2. End 6e is exposed on the end face 2b. End 6e is connected to the external electrode 4. In this embodiment, end 6e is directly connected to the external electrode 4. End 6e constitutes a connecting end that is connected to the external electrode 4. End 6e includes not only one end of the internal electrode 6, but also a region from one end of the internal electrode 6 up to a predetermined length. Therefore, end 6e has the predetermined length in the second direction D2.

[0035] In this embodiment, the end 6e includes a surface 6e1 exposed to the end face 2b, a portion 6e2 located closer to the internal electrode 5 and extending in the second direction D2, and a portion 6e3 located on the opposite side of portion 6e2 and extending in the second direction D2. The edge 6a includes portion 6e2 of the end 6e. The end 6e includes a portion included in the edge 6a and a portion not included in the edge 6a.

[0036] End 6f is located opposite to end 6e in the second direction D2. End 6f is located inside the element 2 and is not exposed on the outer surface of the element 2. End 6f is spaced apart from each end face 2a, 2b. End 6f is embedded in the element 2 and is in contact only with the element 2. Viewed from the third direction D3, end 6f is spaced apart from the external electrode 3 and does not overlap with the external electrode 3. Similar to end 6e, end 6f also includes a region from the other end of the internal electrode 6 up to a predetermined length. Therefore, end 6f also has the predetermined length in the second direction D2.

[0037] In this embodiment, end 6f includes a surface 6f1 that constitutes the tip surface of the internal electrode 6, a portion 6f2 located closer to the internal electrode 5 and extending in the second direction D2, a portion 6f3 located on the opposite side of portion 6f2 and extending in the second direction D2, and corners 6f4 and 6f5. Corner 6f4 is located between surface 6f1 and portion 6f2. Surface 6f1 and portion 6f2 are adjacent to corner 6f4. Corner 6f5 is located between surface 6f1 and portion 6f3. Surface 6f1 and portion 6f3 are adjacent to corner 6f5. Edge 6a includes portion 6f2 of end 6f. End 6f includes a portion included in edge 6a and a portion not included in edge 6a. For example, if end 6e constitutes the first end, end 6f constitutes the second end.

[0038] The external electrodes 3,4 and the internal electrodes 5,6 contain a conductive material. The conductive material may include, for example, Ag, Pd, Au, Pt, Cu, Ni, Al, Mo, or W. The conductive material may also include, for example, an Ag / Pd alloy, an Ag / Cu alloy, an Ag / Au alloy, or an Ag / Pt alloy. The external electrodes 3,4 and the internal electrodes 5,6 may contain the same conductive material. The external electrodes 3,4 and the internal electrodes 5,6 may contain different conductive materials.

[0039] External electrodes 3 and 4 are formed, for example, by baking a conductive paste applied to the outer surface of the base body 2. The conductive paste for forming the external electrodes 3 and 4 includes the conductive material described above. Internal electrodes 5 and 6 are formed, for example, by baking a conductive paste applied to an insulating green sheet together with the insulating green sheet. The conductive paste is applied to the insulating green sheet, for example, by printing. The conductive paste for forming the internal electrodes 5 and 6 also includes the conductive material described above.

[0040] As shown in Figures 2 to 5, the discharge assist portion 7 is located inside the base body 2. The discharge assist portion 7 is spaced apart from the outer surface of the base body 2. The discharge assist portion 7 is not exposed from the base body 2. The discharge assist portion 7 has a pair of opposing edges 7a, 7b and a pair of opposing edges 7c, 7d. The pair of edges 7a, 7b face each other in the first direction D1, and the pair of edges 7c, 7d face each other in the second direction D2. When viewed from the third direction D3, the discharge assist portion 7 has a rectangular shape defined by the four edges 7a, 7b, 7c, 7d. The rectangular shape includes shapes with rounded corners and shapes with rounded corners. The discharge assist portion 7 is spaced apart from the outer surface of the base body 2. The discharge assist portion 7 is not exposed from the base body 2.

[0041] The discharge assist section 7 further has a pair of surfaces 7e and 7f that face each other. The pair of surfaces 7e and 7f face each other in a third direction D3. Surface 7e is in contact with the internal electrodes 5 and 6. Surface 7e is in contact with surface 5c of internal electrode 5 and surface 6c of internal electrode 6. The internal electrodes 5 and 6 are arranged on surface 7e. Surface 7e includes a region covered by the internal electrodes 5 and 6 and a region exposed from the internal electrodes 5 and 6. Surface 7f is in contact with the base body 2. The entire surface 7f is covered by the base body 2. The discharge assist section 7 is in contact with the internal electrodes 5 and 6 and connects the internal electrodes 5 and 6 to each other. The internal electrodes 5 and 6 are connected to each other via the discharge assist section 7. The discharge assist section 7, together with the internal electrodes 5 and 6, constitutes a transient voltage suppressor. The transient voltage suppressor has transient voltage absorption performance.

[0042] The width of the discharge assist section 7 is, for example, 0.03 mm or more and 0.9 mm or less. The length of the discharge assist section 7 is, for example, 0.03 mm or more and 1.6 mm or less. The thickness of the discharge assist section 7 is, for example, 0.5 μm or more and 10 μm or less. In this embodiment, the width, length, and thickness of the discharge assist section 7 are 0.2 mm, 0.3 mm, and 2 μm, respectively. The width, length, and thickness of the discharge assist section 7 are defined, for example, by the length in the first direction D1, the length in the second direction D2, and the length in the third direction D3, respectively.

[0043] The discharge assist unit 7 includes an insulator and metal particles. The insulator is, for example, made of a ceramic material. The ceramic material is selected from the group consisting of, for example, Fe2O3, NiO, CuO, ZnO, MgO, SiO2, TiO2, MnCO3, SrCO3, CaCO3, BaCO3, Al2O3, ZrO2, and B2O3. The discharge assist unit 7 may contain only one type of ceramic material selected from this group, or it may contain two or more types of ceramic materials selected from this group. The metal particles include, for example, Ag, Pd, Au, Pt, Ag / Pd alloy, Ag / Cu alloy, Ag / Au alloy, or Ag / Pt alloy. The discharge assist unit 7 may also contain semiconductor particles. The semiconductor particles are, for example, made of RuO2. The discharge assist unit 7 may also contain glass.

[0044] The discharge assist section 7 is formed, for example, by firing a slurry applied to an insulating green sheet together with the insulating green sheet. The slurry contains the above-mentioned ceramic material and metal particles. The slurry is applied to the insulating green sheet, for example, by printing.

[0045] As shown in Figures 3 to 5, a cavity S is formed inside the base body 2. The cavity S is spaced apart from the outer surface of the base body 2. The surfaces defining the cavity S include the inner wall of the base body 2, the edge 5a and surface 5d of the internal electrode 5, and the edge 6a and surface 6d of the internal electrode 6. The surfaces defining the cavity S also include the areas exposed from the internal electrodes 5 and 6 of the discharge assist unit 7. The areas of the discharge assist unit 7 exposed from the internal electrodes 5 and 6 are the areas exposed to the cavity S. The discharge assist unit 7 has an area exposed to the cavity S.

[0046] Viewed from the third direction D3, the end S1 of the cavity S in the first direction D1 is located inside the edge 5b of the internal electrode 5. Viewed from the third direction D3, the end S2 of the cavity S in the first direction D1 is located inside the edge 6b of the internal electrode 6. Viewed from the third direction D3, the end S3 of the cavity S in the second direction D2 is located inside the edge 6f of the internal electrode 6. Viewed from the third direction D3, the end S4 of the cavity S in the second direction D2 is located inside the edge 5f of the internal electrode 5.

[0047] The cavity S is formed, for example, by firing an organic lacquer applied to an insulating green sheet together with the insulating green sheet. The cavity S is formed by the burning away of the organic lacquer. The organic lacquer contains an organic solvent and an organic binder. The organic lacquer is applied to the insulating green sheet, for example, by printing.

[0048] As shown in Figures 3 to 5, the edges 5a of the internal electrode 5 and the edges 6a of the internal electrode 6 are exposed to the cavity S. In this embodiment, a portion 5a1 of edge 5a and a portion 6a1 of edge 6a are exposed to the cavity S. The portions 5a1 and 6a1 face each other within the cavity S. The portions 5a1 and 6a1 face each other in the first direction D1. The portions 5a1 and 6a1 are in contact with the discharge assist portion 7. The discharge assist portion 7 is arranged within the base body 2 so as to be in contact with the portions 5a1 and 6a1. The portions 5a1 and 6a1 include a portion in contact with the discharge assist portion 7 and a portion not in contact with the discharge assist portion 7.

[0049] As described above, since the end S4 of the cavity S is located inside the end 5f of the internal electrode 5, the portion 5a1 exposed in the cavity S does not include the end 5f or the corners 5f4 and 5f5 that the end 5f contains. Similarly, since the end S3 of the cavity S is located inside the end 6f of the internal electrode 6, the portion 6a1 exposed in the cavity S does not include the end 6f or the corners 6f4 and 6f5 that the end 6f contains. Therefore, the corners 5f4 and 5f5 and the corners 6f4 and 6f5 are not exposed in the cavity S.

[0050] As shown in Figure 3, when viewed from a third direction D3, the pair of edges 7a and 7b of the discharge assist section 7 are located inside the cavity S. In this embodiment, when viewed from a third direction D3, edge 7a is located inside edge S1, and edge 7b is located inside edge S2. As described above, when viewed from a third direction D3, edge S1 is located inside edge 5b of the internal electrode 5, and edge S2 is located inside edge 6b of the internal electrode 6. Therefore, when viewed from a third direction D3, edge 7a is located inside edge 5b, and edge 7b is located inside edge 6b. Edge 7a is in contact with the internal electrode 5. Edge 7a is located inside the periphery of the internal electrode 5. Edge 7b is in contact with the internal electrode 6. Edge 7b is located inside the periphery of the internal electrode 6. The periphery of the internal electrode 5 is defined by the edges 5a, 5b and surfaces 5e1, 5f1, and the periphery of the internal electrode 6 is defined by the edges 6a, 6b and surfaces 6e1, 6f1.

[0051] The pair of edges 7c and 7d of the discharge assist section 7 are exposed to the cavity S. In this embodiment, a portion of the pair of edges 7c and 7d is exposed to the cavity S. The pair of edges 7c and 7d includes a portion exposed to the cavity S and a portion not exposed to the cavity S. Of the pair of edges 7c and 7d, the portion not exposed to the cavity S is in contact with the internal electrodes 5 and 6.

[0052] Viewed from the third direction D3, the pair of edge margins 7c and 7d of the discharge assist portion 7 are also located inside the cavity S. In this embodiment, viewed from the third direction D3, edge margin 7c is located inside edge S3, and edge margin 7d is located inside edge S4. As described above, viewed from the third direction D3, edge S3 is located inside edge 6f of the internal electrode 6, and edge S4 is located inside edge 5f of the internal electrode 5. Therefore, viewed from the third direction D3, edge margin 7c is located inside edge 6f, and edge margin 7d is located inside edge 5f. Edges 5f and 6f are not in contact with the discharge assist portion 7. The corners 5f4 and 5f5 included in edge 5f and the corners 6f4 and 6f5 included in edge 6f are not in contact with the discharge assist portion 7.

[0053] As shown in Figures 3 and 4, the length d1 of the discharge assist portion 7 in the second direction D2 between a portion 5a1 of the edge 5a of the internal electrode 5 and a portion 6a1 of the edge 6a of the internal electrode 6 is greater than the distance d2 between the edge 7c of the discharge assist portion 7 and the edge S3 of the cavity S in the second direction D2, and the distance d3 between the edge 7d of the discharge assist portion 7 and the edge S4 of the cavity S in the second direction D2. As described above, the length of the discharge assist portion 7 is determined by the length d1 of the discharge assist portion 7 in the second direction D2. Therefore, the length of the discharge assist portion 7 is greater than the distances d2 and d3. The distances d2 and d3 may be the same or different. Figure 4 shows a cross-section obtained by cutting the body 2 with a plane perpendicular to the second direction D2 at the position where the cavity S is formed, viewed in the direction from the internal electrode 6 to the internal electrode 5 within the first direction D1. In this embodiment, even when the above cross-section is viewed in the direction from the internal electrode 5 to the internal electrode 6 within the first direction D1, the relationship between length d1 and the spacing d2 and spacing d3 between part 5a1 and part 6a1 is the same as the relationship described above.

[0054] The length d1 of the discharge assist section 7 is, as described above, for example, 0.03 mm or more and 1.6 mm or less. The spacing d2 is, for example, 0 mm or more and 0.6 mm or less. The spacing d3 is, for example, 0 mm or more and 0.6 mm or less. In this embodiment, the length d1 is 0.3 mm, the spacing d2 is 0.1 mm, and the spacing d3 is 0.1 mm.

[0055] As shown in Figure 5, the discharge assist section 7 is curved in a cross-section along the third direction D3. The cross-section along the third direction D3 shown in Figure 5 is obtained by cutting the base body 2 with a plane perpendicular to the first direction D1 at the position where the cavity S is formed. The discharge assist section 7 is curved to exhibit an arc shape in a cross-section along the third direction D3. Surfaces 7e and 7f are curved to exhibit an arc shape. The internal electrodes 5 and 6 are also curved in a cross-section along the third direction D3. The internal electrodes 5 and 6 are curved to follow the discharge assist section 7 in a cross-section along the third direction D3. In this embodiment, a part of surface 5c of the internal electrode 5 and a part of surface 6c of the internal electrode 6 are curved to follow surface 7e of the discharge assist section 7.

[0056] As explained above, in the transient voltage protection device 1, the discharge assist portion 7 has a pair of edges 7c and 7d that face each other in the second direction D2 and are exposed within the cavity S. Therefore, in the second direction D2, the length of the discharge assist portion 7 is less than the length of the cavity S. Between the opposing edges 5a (part 5a1) and 6a (part 6a1), the discharge assist portion 7 does not have a region that is not exposed to the cavity S. As a result, the transient voltage protection device 1 is less likely to cause discharge that does not pass through the cavity S. In the transient voltage protection device 1, a portion 5a1 of edge 5a and a portion 6a1 of edge 6a face each other within the cavity S, and portion 5a1 does not include the corners 5f4, 5f5 of edge 5f, and portion 6a1 does not include the corners 6f4, 6f5 of edge 6f. Therefore, the corners 5f4, 5f5 and corners 6f4, 6f5 are not exposed to the cavity S and are not in contact with the discharge assist portion 7. As a result, the transient voltage protection device 1 reliably generates discharge in the region of the discharge assist portion 7 that is exposed to the cavity S. Based on the above, the transient voltage protection device 1 suppresses variations in the clamp voltage.

[0057] In the transient voltage protection device 1, the discharge assist section 7 has a pair of edges 7a and 7b that face each other in the first direction D1. Edge 7a is in contact with the internal electrode 5. Edge 7b is in contact with the internal electrode 6. The transient voltage protection device 1 ensures more reliable discharge in the region exposed to the cavity S of the discharge assist section 7. Therefore, the transient voltage protection device 1 further suppresses variations in the clamp voltage.

[0058] In the transient voltage protection device 1, the discharge assist section 7 is curved in cross-section along the third direction D3. The transient voltage protection device 1 can easily increase the opposing area of ​​the pair of internal electrodes 5 and 6. Therefore, the transient voltage protection device 1 can suppress the degradation of its transient voltage protection characteristics.

[0059] In transient voltage protection device 1, the pair of internal electrodes 5 and 6 are curved in cross-section along the third direction D3. The transient voltage protection device 1 can easily increase the opposing area of ​​the pair of internal electrodes 5 and 6. Therefore, the transient voltage protection device 1 can suppress the degradation of its transient voltage protection characteristics.

[0060] In the transient voltage protection device 1, the pair of internal electrodes 5 and 6 are curved in a cross-section along the third direction D3 so as to follow the discharge assist portion 7. The transient voltage protection device 1 can more easily increase the opposing area of ​​the pair of internal electrodes 5 and 6. Therefore, the transient voltage protection device 1 can further suppress the deterioration of the transient voltage protection characteristics.

[0061] In the transient voltage protection device 1, the length d1 of the discharge assist portion 7 in the second direction D2 between a portion 5a1 of the edge 5a of the internal electrode 5 and a portion 6a1 of the edge 6a of the internal electrode 6 is greater than the distance d2 between the edge 7c of the discharge assist portion 7 and the edge S3 of the cavity S in the second direction D2, and the distance d3 between the edge 7d of the discharge assist portion 7 and the edge S4 of the cavity S in the second direction D2. The transient voltage protection device 1 ensures more reliable discharge in the region exposed to the cavity S of the discharge assist section 7. Therefore, the transient voltage protection device 1 further suppresses variations in the clamp voltage.

[0062] In the transient voltage protection device 1, the pair of edges 7c and 7d of the discharge assist portion 7 are located inside the cavity S when viewed from the third direction D3. Therefore, in the second direction D2, the length of the discharge assist portion 7 is less than the length of the cavity S. Between the pair of opposing internal electrodes 5 and 6, the discharge assist portion 7 has no region that is not exposed to the cavity S. As a result, the transient voltage protection device 1 is less likely to cause discharge that does not pass through the cavity S. In the transient voltage protection device 1, the corners 5f4, 5f5 and 6f4, 6f5 are not exposed to the cavity S and are not in contact with the discharge assist portion 7. Therefore, the transient voltage protection device 1 reliably generates discharge in the region exposed to the cavity S of the discharge assist portion 7. Based on the above, the transient voltage protection device 1 suppresses variations in the clamp voltage.

[0063] While embodiments of the present invention have been described above, the present invention is not necessarily limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0064] Edge 7a does not have to be in contact with the internal electrode 5, and edge 7b does not have to be in contact with the internal electrode 6. In this case, edge 7a may be located outside the edge 5b of the internal electrode 5 in the first direction D1, and edge 7b may be located outside the edge 6b of the internal electrode 6 in the first direction D1. A transient voltage protection device 1 in which edge 7a is in contact with the internal electrode 5 and edge 7b is in contact with the internal electrode 6 further suppresses variations in the clamp voltage, as described above.

[0065] The discharge assist portion 7 does not need to be curved in cross-section along the third direction D3. A transient voltage protection device 1 in which the discharge assist portion 7 is curved in cross-section along the third direction D3 can suppress deterioration of transient voltage protection characteristics, as described above.

[0066] The pair of internal electrodes 5 and 6 do not need to be curved in cross-section along the third direction D3. A transient voltage protection device 1 in which the pair of internal electrodes 5 and 6 are curved in cross-section along the third direction D3 can suppress the deterioration of transient voltage protection characteristics, as described above.

[0067] The pair of internal electrodes 5 and 6 do not necessarily have to be curved in a cross-section along the third direction D3 to align with the discharge assist portion 7. A transient voltage protection device 1 in which the pair of internal electrodes 5 and 6 are curved in a cross-section along the third direction D3 to align with the discharge assist portion 7 can further suppress the deterioration of transient voltage protection characteristics, as described above.

[0068] Between a portion 5a1 of the edge 5a of the internal electrode 5 and a portion 6a1 of the edge 6a of the internal electrode 6, the length d1 of the discharge auxiliary portion 7 in the second direction D2 does not need to be greater than the distance d2 between the edge 7c of the discharge auxiliary portion 7 and the edge S4 of the cavity S in the second direction D2, and the distance d3 between the edge 7d of the discharge auxiliary portion 7 and the edge S3 of the cavity S in the second direction D2. A transient voltage protection device 1 in which the length d1 is greater than the distances d2 and d3 further suppresses variations in the clamp voltage, as described above.

[0069] As can be seen from the descriptions of the embodiments described above, this specification includes disclosures of the following embodiments. (Note 1) A base body with a cavity formed inside, A pair of external electrodes arranged on the aforementioned body, A pair of internal electrodes, each having an edge, are arranged within the substrate such that a portion of each edge faces each other in a first direction within the cavity, The body comprises a discharge assist portion disposed within the element so as to be in contact with a portion of the edge of each of the pair of internal electrodes, Each of the pair of internal electrodes has the edge, The first end, which is exposed on the outer surface of the body and connected to the corresponding external electrode of the pair of external electrodes, A second end, located on the opposite side of the first end and including a corner, The discharge assist portion has a pair of edges that face each other in a second direction intersecting the first direction and are exposed within the cavity, A transient voltage protection device wherein the portion of the edge of each of the pair of internal electrodes does not include the corner. (Note 2) The transient voltage protection device according to Appendix 1, wherein the discharge assist portion has another pair of edges that face each other in the first direction and are in contact with the corresponding internal electrodes of the pair of internal electrodes. (Note 3) The transient voltage protection device according to Appendix 1 or 2, wherein the discharge assist portion is curved in a cross-section along a third direction intersecting the first and second directions. (Note 4) The transient voltage protection device described in Appendix 3, wherein the pair of internal electrodes are curved in the cross-section along the third direction. (Note 5) The transient voltage protection device according to Appendix 4, wherein the pair of internal electrodes are curved in the cross-section along the third direction so as to follow the discharge assist portion. (Note 6) A transient voltage protection device according to any one of the appendices 1 to 6, wherein, between the portion of the edge of the pair of internal electrodes, the length of the discharge assist portion in the second direction is greater than the distance in the second direction between the corresponding edge and end of the pair of edge of the discharge assist portion and the two ends of the cavity in the second direction. (Note 7) A base body with a cavity formed inside, A pair of external electrodes arranged on the aforementioned body, A pair of internal electrodes are arranged within the body so as to face each other in a first direction and are exposed to the cavity, The body comprises a discharge assist unit arranged within the body so as to be in contact with the pair of internal electrodes, Each of the pair of internal electrodes is The first end of the pair of external electrodes, which is connected to the corresponding external electrode, It has a second end located on the opposite side of the first end and including a corner, The discharge assist portion has a pair of edges that face each other in a second direction intersecting the first direction, The pair of edges are located inside the cavity when viewed from a third direction intersecting the first and second directions. The aforementioned corner portion is not exposed to the cavity and is not in contact with the discharge assist portion, thereby providing a transient voltage protection device. [Explanation of Symbols]

[0070] 1...Transient voltage protection device, 2...Element body, 3,4...External electrode, 5,6...Internal electrode, 5a,6a...Edge, 5a1,6a1...Part, 5e,5f,6e,6f...Edge, 5f4,5f5,6f4, 6f5... Corner, 7... Discharge auxiliary part, 7a, 7b, 7c, 7d... Edge, D1... First direction, D2... Second direction, D3... Third direction, d1... Length, d2, d3... Spacing, S... Cavity, S3, S4... End.

Claims

1. A base body with a cavity formed inside, A pair of external electrodes arranged on the aforementioned body, A pair of internal electrodes, each having an edge, are arranged within the substrate such that a portion of each edge faces each other in a first direction within the cavity, The body comprises a discharge assist portion disposed within the element so as to be in contact with a portion of the edge of each of the pair of internal electrodes, Each of the pair of internal electrodes has the edge, The first end, which is exposed on the outer surface of the body and connected to the corresponding external electrode of the pair of external electrodes, A second end, located on the opposite side of the first end and including a corner, The discharge assist portion has a pair of edges that face each other in a second direction intersecting the first direction and are exposed within the cavity, The portion of the edge of each of the pair of internal electrodes does not include the corner portion. A transient voltage protection device in which, between a portion of the edge of the pair of internal electrodes, the length of the discharge assist portion in the second direction is greater than the distance in the second direction between the corresponding edge and end of the pair of edge of the discharge assist portion and the two ends of the cavity in the second direction.

2. The transient voltage protection device according to claim 1, wherein the discharge assist portion has another pair of edges that face each other in the first direction and are in contact with the corresponding internal electrodes of the pair of internal electrodes.

3. The transient voltage protection device according to claim 1 or 2, wherein the discharge assist portion is curved in a cross-section along a third direction intersecting the first direction and the second direction.

4. The transient voltage protection device according to claim 3, wherein the pair of internal electrodes are curved in the cross-section along the third direction.

5. The transient voltage protection device according to claim 4, wherein the pair of internal electrodes are curved in the cross-section along the third direction so as to follow the discharge assist portion.

6. A base body with a cavity formed inside, A pair of external electrodes arranged on the aforementioned body, A pair of internal electrodes are arranged within the body so as to face each other in a first direction and are exposed to the cavity, The system comprises a single discharge assist unit disposed within the body so as to be in contact with the pair of internal electrodes, Each of the pair of internal electrodes is The first end of the pair of external electrodes, which is connected to the corresponding external electrode, It has a second end located on the opposite side of the first end and including a corner, The single discharge assist portion has a pair of edges facing each other in a second direction intersecting the first direction, and another pair of edges facing each other in the first direction, The pair of edges are located inside the cavity when viewed from a third direction intersecting the first and second directions. The other pair of edges, when viewed from the third direction, are located inside the cavity. A transient voltage protection device in which the aforementioned corner portion is not exposed to the cavity and is not in contact with the single discharge assist portion.

7. The transient voltage protection device according to claim 6, wherein when the single discharge assist portion and the cavity are viewed from the third direction, the entire single discharge assist portion is located inside the cavity.

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