JP4978302B2 - Varistor and light emitting device - Google Patents

Description

  The present invention relates to a varistor and a light emitting device including the varistor.

As a varistor, an element body having a varistor element body that exhibits voltage non-linear characteristics, and a pair of internal electrodes disposed inside the varistor element body with a part of the varistor element body interposed therebetween, and an outside of the element body Some have a pair of terminal electrodes arranged on the surface and connected to corresponding internal electrodes, respectively (for example, see Patent Document 1).
JP 2002-246207 A

  By the way, the varistor can be protected from an ESD (Electrostatic Discharge) surge by being connected in parallel to an electronic element such as a semiconductor light emitting element or an FET (Field Effect Transistor). Some of these electronic elements generate heat during operation. When the electronic element becomes high temperature, the characteristic of the element itself is deteriorated and the operation is affected. For this reason, it is necessary to efficiently dissipate the generated heat.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a varistor and a light-emitting device that can dissipate heat efficiently.

  A varistor according to the present invention includes an element body that exhibits a voltage non-linear characteristic and includes a region including first and second surfaces, and an electrode disposed on the first surface of the region included in the element body. And at least two electrodes each having a portion, and a heat dissipating part having a higher thermal conductivity than the region of the element body and arranged to be thermally connected to the second surface of the region, The said area | region which a body has consists of a semiconductor ceramic, and a thermal radiation part consists of a composite material of a metal and a metal oxide, It is characterized by the above-mentioned.

  In the varistor according to the present invention, the portion located between the electrode portions of the at least two electrodes in the above-mentioned region of the element body develops the voltage non-linear characteristics. Therefore, the varistor is composed of the portion and the at least two electrodes. Ingredients are composed. In the present invention, the heat radiating portion is made of a composite material of metal and metal oxide, and has a higher thermal conductivity than the above-mentioned region of the element body and is arranged to be thermally connected to the second surface of the region. Therefore, the heat transferred to the varistor can be efficiently dissipated from the heat radiating section.

  Preferably, the heat dissipating part is disposed so as to contact the second surface of the region of the element body. In this case, the heat transmitted to the varistor can be efficiently transmitted to the heat radiating portion.

  Preferably, the heat dissipating part is electrically connected to the second surface of the region of the element body. In this case, since the portion located between the electrode portion of the at least two electrodes and the heat radiating portion in the above-mentioned region of the element body develops the voltage non-linear characteristics, the portion, the at least two electrodes, and the heat radiating portion A varistor component can be formed.

  Preferably, the heat dissipation portion includes a first surface facing the second surface of the region included in the element body and a plurality of second surfaces not facing the second surface of the region included in the element body. And at least 1 surface is exposed among the several 2nd surfaces of a thermal radiation part. In this case, the heat transmitted to the varistor can be more efficiently dissipated from the heat radiating section.

  Preferably, the heat dissipation portion includes a first surface facing the second surface of the region included in the element body and a plurality of second surfaces not facing the second surface of the region included in the element body. In this case, the metal is conducted from the first surface of the heat radiating portion to at least one of the plurality of second surfaces. In this case, in the heat radiating portion, a heat radiating path made of metal is easily formed, and the efficiency of heat transfer in the heat radiating portion and heat dissipation from the heat radiating portion can be increased.

  Preferably, the heat dissipation part includes Ag as a main component of the metal. Ag has a relatively high thermal conductivity and can increase the efficiency of heat transfer in the heat radiating section and heat dissipation from the heat radiating section.

  Preferably, the element body is made of a semiconductor ceramic. More preferably, the element body contains ZnO as a main component, and the heat dissipation part contains ZnO as a metal oxide.

  Preferably, the element body and the heat dissipation part are formed by simultaneous firing. In this case, the manufacturing process can be simplified.

  A light-emitting device according to the present invention is a light-emitting device including a light-emitting element and a varistor, and the varistor exhibits a voltage non-linear characteristic and has a region including first and second surfaces. And at least two electrodes each having an electrode portion disposed on the first surface of the region of the element body; and a heat conductivity higher than that of the region of the element body and the second surface of the region And the heat dissipation part is made of a composite material of a metal and a metal oxide, and the light emitting element is a varistor. Are electrically connected to at least two electrodes so as to be connected in parallel.

  In the light emitting device according to the present invention, the portion located between the electrode portions of each of the at least two electrodes in the region of the element body develops the voltage non-linear characteristics. A varistor component is constructed. Thereby, a light emitting element can be protected from an ESD surge. In the present invention, since the light emitting element and at least two electrodes of the varistor are physically connected, heat generated in the light emitting element is transmitted to the varistor through at least two electrodes (electrode portions). The heat radiating portion is made of a composite material of metal and metal oxide, and has a higher thermal conductivity than the above-mentioned region of the element body and is disposed so as to be thermally connected to the second surface of the region. Therefore, the heat transmitted to the varistor can be efficiently dissipated from the heat radiating portion.

  According to the varistor and the light emitting device according to the present invention, it is possible to efficiently dissipate heat.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  First, with reference to FIG.1 and FIG.2, the structure of the varistor V1 which concerns on this embodiment is demonstrated. FIG. 1 is a schematic perspective view showing a varistor according to the present embodiment. FIG. 2 is a schematic cross-sectional view showing the varistor according to the present embodiment. As shown in FIGS. 1 and 2, the varistor V <b> 1 includes a varistor element body 10, a pair of first and second electrodes 20 and 30, and a heat radiating portion 40, and has a substantially rectangular parallelepiped shape.

  The varistor element body 10 has a rectangular parallelepiped shape, and includes first and second main surfaces 11 and 12, first and second end surfaces 13 and 14, and first and second side surfaces 15 and 16. Yes. The first and second main surfaces 11 and 12 have a rectangular shape and face each other. The first and second end faces 13 and 14 extend in the short side direction of the first and second main faces 11 and 12 so as to connect the first and second main faces 11 and 12 and face each other. ing. The first and second side surfaces 15 and 16 extend in the long side direction of the first and second main surfaces 11 and 12 so as to connect the first and second main surfaces 11 and 12 and face each other. ing.

  The varistor element body 10 is made of a semiconductor ceramic and is a sintered body that exhibits voltage nonlinear characteristics (hereinafter referred to as varistor characteristics). The varistor element body 10 is configured as a laminated body in which a plurality of varistor layers are laminated. In the actual varistor V1, the plurality of varistor layers are integrated so that the boundary between them cannot be visually recognized. The varistor layer contains ZnO (zinc oxide) as a main component and also includes rare earth metal elements, Co, group IIIb elements (B, Al, Ga, In), Si, Cr, Mo, alkali metal elements (K, K) as subcomponents. Rb, Cs) and simple metals such as alkaline earth metal elements (Mg, Ca, Sr, Ba) and oxides thereof. In the present embodiment, the varistor layer contains Pr, Co, Cr, Ca, Si, K, Al, and the like as subcomponents.

  In the present embodiment, Pr is used as the rare earth metal. Pr is a material for expressing varistor characteristics. The reason for using Pr is that voltage non-linearity is excellent and characteristic variation during mass production is small.

  In the present embodiment, Ca is used as the alkaline earth metal element. Ca becomes a material for controlling the sinterability of the ZnO-based varistor material and improving the moisture resistance. The reason for using Ca is to improve voltage nonlinearity.

  Although content of ZnO in a varistor layer is not specifically limited, When the whole material which comprises a varistor layer is 100 mass%, it is 99.8-69.0 mass% normally. The thickness of the varistor layer is, for example, about 5 to 60 μm.

  The first and second electrodes 20 and 30 have first electrode portions 21 and 31 and second electrode portions 22 and 32, respectively.

  The first electrode portion 21 of the first electrode 20 and the first electrode portion 31 of the second electrode 30 are disposed on the first main surface 11 of the varistor element body 10. Each of the first electrode portions 21 and 31 has a rectangular shape when viewed from a direction perpendicular to the first main surface 11 and is symmetrically arranged with a space therebetween. The first electrode portion 21 is not exposed to the first end surface 13 and the first and second side surfaces 15 and 16 of the varistor element body 10, and is only a predetermined distance from the edge of the first main surface 11. It extends to the position. The first electrode portion 31 is not exposed to the second end face 14 and the first and second side faces 15 and 16 of the varistor element body 10, and is only a predetermined distance from the edge of the first main face 11. It extends to the position.

  The first electrode portions 21 and 31 contain a metal (for example, Ag, Ag—Pd alloy, or Au) as a main component. The first electrode portions 21 and 31 are formed by firing a conductive paste containing conductive metal powder (for example, Ag powder, Ag-Pd alloy powder, Au powder, or the like).

  The first electrode portions 21 and 31 are covered with an insulating layer 50 containing glass as a main component, and are electrically insulated from each other. In the insulating layer 50, openings 51 and 52 are formed at positions corresponding to the first electrode portions 21 and 31, respectively. Thereby, part of the surface of the first electrode portions 21 and 31 is exposed from the insulating layer 50. The insulating layer 50 also functions as a layer that protects the first main surface 11 and the first electrode portions 21 and 31 of the varistor element body 10.

  The second electrode portions 22 and 32 are symmetrically disposed apart from each other on the outer surface of the insulating layer 50 so as to correspond to the first electrode portions 21 and 31. The second electrode portions 22 and 32 also extend into the openings 51 and 52 of the insulating layer 50 and are in contact with the first electrode portions 21 and 31 exposed from the insulating layer 50. Accordingly, the first electrode portion 21 and the second electrode portion 22 are electrically and physically connected, and the first electrode portion 31 and the second electrode portion 32 are electrically and physically connected. The The second electrode portions 22 and 32 serve as connection ends of an electronic element such as the semiconductor light emitting element 61 (see FIG. 10), and function as pad electrodes on which the electronic element is mounted.

  The second electrode portions 22 and 32 contain a metal (for example, Ag or Au) as a main component. The second electrode portions 22 and 32 are formed by baking a conductive paste containing conductive metal powder (for example, Ag powder or Au powder). The second electrode portions 22 and 32 may be formed by a plating method such as a sputtering method.

  The heat radiating portion 40 has a substantially rectangular parallelepiped shape like the varistor element body 10, and includes first and second main surfaces 41 and 42, first and second end surfaces 43 and 44, and first and second side surfaces. 45 and 46 are included. The first and second main surfaces 41 and 42 have a rectangular shape and face each other. The first and second end surfaces 43 and 44 extend in the short side direction of the first and second main surfaces 41 and 42 so as to connect the first and second main surfaces 41 and 42 and face each other. ing. The first and second side surfaces 45 and 46 extend in the long side direction of the first and second main surfaces 41 and 42 so as to connect the first and second main surfaces 41 and 42 and face each other. ing.

  The heat radiation part 40 is a sintered body made of a composite material of a metal and a metal oxide, and is configured as a laminated body in which a plurality of layers are laminated. In the actual varistor V1, the plurality of layers constituting the heat radiation part 40 are integrated so that the boundary between them cannot be visually recognized.

The heat radiating part 40 contains a metal and has a higher thermal conductivity than the thermal conductivity of the varistor element body 10 (in this embodiment, the thermal conductivity of ZnO, which is the main component of the varistor element body 10). In the present embodiment, for example, Ag is used as the metal and ZnO is used as the metal oxide. Instead of Ag, an Ag—Pd alloy or Pd may be included, or a plurality of these metals may be included. However, Ag is preferably used from the viewpoint of thermal conductivity. Instead of ZnO, Al ₂ O ₃ , SiO ₂ or ZrO ₂ may be included, and a plurality of these metal oxides may be included.

  The heat radiating part 40 is joined to the varistor element body 10 in a state where the first main surface 41 of the heat radiating part 40 is in contact with the second main surface 12 of the varistor element body 10. Thereby, the heat radiating part 40 is thermally connected to the second main surface 12 of the varistor element body 10. In the present embodiment, the heat radiating part 40 is also electrically connected to the second main surface 12 of the varistor element body 10. The heat radiating part 40 is formed by firing simultaneously with the varistor element body 10.

  The inside of the heat radiating portion 40 is in contact with the second main surface 12 of the varistor element body 10 from the first main surface 41 that contacts and faces the second main surface 12 of the varistor element body 10 by Ag which is a metal. The surfaces 42 to 46 that are not connected are electrically connected.

  An insulating layer 55 mainly composed of glass is disposed on the second main surface 42 of the heat radiating portion 40. The 2nd main surface 42 of the thermal radiation part 40 is covered with the insulating layer 55, and the insulation of the thermal radiation part 40 is ensured. The first and second end faces 43 and 44 and the first and second side faces 45 and 46 of the heat radiation part 40 are exposed.

  Although content of Ag in the thermal radiation part 40 is not specifically limited, When the whole material which comprises the thermal radiation part 40 is 100 mass%, it is preferable that it is 5-95 mass%. When the content of Ag is 5% or more, the above-described conduction path can be formed. When the content of Ag is more than 95%, the bonding strength between the heat radiation part 40 and the varistor element body 10 is weakened, and the heat radiation part 40 and the varistor element body 10 may peel off.

  Subsequently, a manufacturing process of the above-described varistor V1 will be described.

  First, ZnO which is a main component constituting each varistor layer of the varistor element body 10 and a small amount of additive such as Pr, Co, Cr, Ca, Si, K and Al metals or oxides are in a predetermined ratio. In this way, the varistor material is prepared by mixing each component and mixing each component. Then, an organic binder, an organic solvent, an organic plasticizer, etc. are added to this varistor material, and it mixes and grinds for about 20 hours using a ball mill etc., and obtains a slurry.

  The slurry is applied onto a film made of, for example, polyethylene terephthalate by a known method such as a doctor blade method, and then dried to form a film having a thickness of about 30 μm. The film thus obtained is peeled from the film to obtain a green sheet for a varistor element body.

  Further, Ag and ZnO, which are the main components constituting each layer of the heat radiating part 40, are weighed so as to have a predetermined ratio, and then each component is mixed to adjust the material. At this time, the adjusted material may contain the above-mentioned trace additive. Then, an organic binder, an organic solvent, an organic plasticizer, etc. are added to this material, and it mixes and grinds for about 20 hours using a ball mill etc., and obtains a slurry. From this slurry, a green sheet for a heat radiating part is obtained by the same method as that for obtaining a green sheet for a varistor element body.

  Next, electrode patterns corresponding to the first electrode portions 21 and 31 of the first and second electrodes 20 and 30 are formed on the varistor element green sheet. These electrode patterns are formed by printing a conductive paste obtained by mixing an organic binder and an organic solvent on a metal powder containing Ag particles as a main component on a varistor element and drying it.

  Next, the green sheet for the heat radiation part, the green sheet for the varistor element body in which the electrode pattern is formed, and the green sheet for the varistor element body in which the electrode part is not formed are stacked in a predetermined order to laminate the sheets. Form the body. And the obtained sheet | seat laminated body is cut | disconnected per chip | tip, and the some divided | segmented green body is obtained.

  Next, the green body is subjected to heat treatment at 180 to 400 ° C. for about 0.5 to 24 hours to remove the binder, and further baked at 850 to 1400 ° C. for about 0.5 to 8 hours. Do. Thereby, a sintered laminate including the varistor element body 10, the first electrode portions 21 and 31, and the heat radiating portion 40 is obtained.

  Next, a glass paste in which glass powder, an organic binder, and an organic solvent are mixed is prepared, and the glass paste is printed on the varistor element body 10 so as to cover the first electrode portions 21 and 31 and dried. Thereby, a glass paste layer is formed on the varistor element body 10. At this time, openings are formed in the glass paste layer formed by printing at positions to be the openings 51 and 52 of the insulating layer 50. Further, the glass paste is printed on the heat radiating portion 40 so as to cover the second main surface 42 of the heat radiating portion 40 and dried. Thereby, a glass paste layer is formed on the heat radiating portion 40.

Then, electrode patterns corresponding to the second electrode portions 22 and 32 are formed on the glass paste layer formed on the varistor element body 10 so as to close the openings. This electrode pattern is formed by printing on a glass paste layer a conductive paste obtained by mixing an organic binder and an organic solvent on a metal powder containing Au particles or Ag particles as a main component, and drying the paste. Then, the insulating layers 50 and 55 and the second electrode portions 22 and 32 are formed by baking these glass paste layers and the electrode pattern at a temperature of 800 ° C. or higher in an O ₂ atmosphere. Through the above process, the varistor V1 shown in FIGS. 1 and 2 is completed.

  In the manufacturing process described above, the first electrode portions 21 and 31 are formed at the same time when the varistor element body 10 and the heat radiating portion 40 are formed by baking, but the present invention is not limited to this. For example, after the varistor element body 10 and the heat radiating portion 40 are formed by firing, a conductive paste may be attached and then baked.

  As described above, in the present embodiment, the portion of the varistor element body 10 located between the first electrode portion 21 and the first electrode portion 31 develops the voltage non-linear characteristics. The first electrode portions 21 and 31 constitute a varistor component.

  In this embodiment, the heat radiating part 40 is made of a composite material of metal (Ag in this embodiment) and metal oxide (ZnO in this embodiment), has a higher thermal conductivity than the varistor element body 10 and has a varistor. Since it arrange | positions so that it may thermally connect with the 2nd main surface 12 of the element | base_body 10, the heat transmitted to the varistor V1 can be efficiently dissipated from the thermal radiation part 40. FIG.

  In the present embodiment, the heat radiating portion 40 is disposed so as to contact the second main surface 12 of the varistor element body 10. Thereby, the heat transmitted to the varistor V1 can be efficiently transmitted to the heat radiating unit 40.

  In the present embodiment, the heat radiating portion 40 is electrically connected to the varistor element body 10. Thereby, the part located between the 1st electrode parts 21 and 31 and the thermal radiation part 40 in the varistor element | base_body 10 expresses a voltage non-linear characteristic, and the said part, the 1st electrode parts 21 and 31, and heat radiation | emission are carried out. It is possible to further configure the varistor component with the portion 40.

  When the distance between the first electrode portions 21 and 31 and the heat radiating portion 40 is larger than the distance between the first electrode portion 21 and the first electrode portion 31, the characteristics of the varistor V1 are as follows. The characteristics of the varistor component formed between the electrode portions 21 and 31 become dominant. On the other hand, when the distance between the first electrode portions 21 and 31 and the heat radiating portion 40 is smaller than the distance between the first electrode portion 21 and the first electrode portion 31, the characteristics of the varistor V1 are as follows. The characteristics of the varistor component formed between the first electrode portions 21 and 31 and the heat radiating portion 40 become dominant. Thus, by changing the relationship between the distance between the first electrode portion 21 and the first electrode portion 31 and the distance between the first electrode portions 21 and 31 and the heat radiating portion 40, the characteristics of the varistor V1 can be improved. It can be easily changed.

  In the present embodiment, the heat radiating section 40 includes a first main surface 41 facing the second main surface 12 of the varistor element body 10 and a plurality of not facing the second main surface 12 of the varistor element body 10. The surfaces 42 to 46 are included, and the first and second end surfaces 43 and 44 and the first and second side surfaces 45 and 46 of the heat radiating portion are exposed. Thereby, the heat transmitted to the varistor V1 can be dissipated more efficiently from the heat radiating section 40.

  In the present embodiment, in the heat radiating portion 40, the metal (Ag) is conducted from the first main surface 41 of the heat radiating portion 40 to the plurality of surfaces 42 to 46. Thereby, in the heat radiating part 40, a heat radiating path by metal is easily formed, and the efficiency of heat transfer in the heat radiating part 40 and heat dissipation from the heat radiating part 40 can be enhanced.

  In this embodiment, the heat radiating part 40 contains Ag as a main component of the metal. Ag has a relatively high thermal conductivity, and it is possible to increase the efficiency of heat transfer in the heat radiating portion 40 and heat dissipation from the heat radiating portion.

  In the present embodiment, the varistor element body 10 and the heat radiating portion 40 are formed by simultaneous firing. Thereby, simplification of the manufacturing process of the varistor V1 is realized, which contributes to improvement in manufacturing efficiency and cost reduction of the varistor V1.

  By the way, the varistor element body 10 and the heat radiation part 40 contain the same ZnO. When the varistor element body 10 and the heat radiating portion 40 are formed by simultaneous firing, the varistor element body 10 is formed at the interface between the second main surface 12 of the varistor element body 10 and the first main surface 41 of the heat radiating section 40. The ZnO contained and the ZnO contained in the heat dissipation part 40 are combined to grow grains. Thereby, the varistor element body 10 and the heat radiating part 40 are thereby firmly joined.

  Further, since the heat radiating part 40 contains Ag, when the varistor element body 10 and the heat radiating part 40 are formed by simultaneous firing, Ag contained in the heat radiating part 40 is the second main component of the varistor element body 10. In the vicinity of the interface between the surface 12 and the first main surface 41 of the heat radiating portion 40, it diffuses into the grain boundary of ZnO which is the main component of the varistor element body 10. As a result, the bonding between the varistor element body 10 and the heat radiating portion 40 is further strengthened. As a result, in the varistor V1, cracks hardly occur between the varistor element body 10 and the heat radiating part 40 during firing, and a sufficient bonding strength between the varistor element body 10 and the heat radiating part 40 can be ensured. it can.

When forming the heat radiation part 40, metal oxide particles coated with a metal coating may be used. As the particles, for example, _Al 2 _{O 3} particles having been subjected to Ag coated by electroless plating and the like. Thus, by using metal oxide particles that have been previously coated with a metal coating, it is possible to reliably form a heat dissipation path using metal.

  Next, first to fourth modified examples of the varistor V1 according to this embodiment will be described with reference to FIGS. 3-9 is a figure which shows the modification of the varistor which concerns on this embodiment.

  In the varistor V <b> 2 according to the first modification shown in FIG. 3, the heat radiating part 40 is thermally connected to the second main surface 12 of the varistor element body 10 via an adhesive layer 57. The varistor V <b> 2 can be obtained by joining the varistor element body 10 formed by firing and the heat radiating portion 40 with an adhesive layer 57. Also in the varistor V <b> 2, the second main surface 12 of the varistor element body 10 and the first main surface 41 of the heat radiating portion 40 face each other through the adhesive layer 57.

  The adhesive layer 57 is made of a resin material such as an epoxy resin or a silicone resin, a conductive adhesive, or a glass material. When the adhesive layer 57 has conductivity, the heat radiating portion 40 is electrically connected to the second main surface 12 of the varistor element body 10. When the adhesive layer 57 does not have conductivity, the insulating layer 55 may be omitted. The thickness of the adhesive layer 57 is set within a range in which the thermal connection between the varistor element body 10 and the heat radiating part 40 is not hindered and the bonding strength between the varistor element body 10 and the heat radiating part 40 can be secured.

  As described above, also in the first modification, the heat radiating portion 40 is thermally connected to the varistor element body 10, and therefore, the heat transferred to the varistor V2 can be efficiently dissipated from the heat radiating portion 40.

  In the varistor V3 according to the second modification shown in FIGS. 4 to 7, the heat radiating part 40 is located in the varistor element body 10, and all the surfaces 41 to 46 of the heat radiating part 40 are connected to the varistor element body 10. It touches. Therefore, all the surfaces 41 to 46 of the heat radiation part 40 are not exposed.

  The varistor element body 10 includes a first element body region 10a, a second element body region 10b, and a third element body region 10c. The first element body region 10 a is a region disposed so as to be in contact with the first main surface 41 of the heat radiating unit 40. The third element body region 10 c is a region arranged so as to be in contact with the second main surface 42 of the heat radiating unit 40. The second element region 10b connects the first element region 10a and the third element region 10c, and the first and second end surfaces 43 and 44 of the heat radiating portion 40, and the first and second elements. This is a region arranged so as to be in contact with the side surfaces 45 and 46. The first element body region 10 a includes a first main surface 11 and a surface 17 that faces the first main surface 11 and is connected to the heat radiating unit 40.

  The varistor element body 10 and the heat dissipating part 40 of the varistor V3 are a plurality of green sheets having a part to be the varistor element body 10 and a part to be the heat dissipating part 40, and a plurality of green sheets having only a part to be the varistor element body 10. Sheets can be prepared, and these green sheets can be laminated in a desired order and fired.

  As described above, in the second modified example, the portion located between the first electrode portion 21 and the first electrode portion 31 in the first element region 10a of the varistor element body 10 is voltage non-linear characteristics. Therefore, the varistor component is constituted by the portion and the first electrode portions 21 and 31.

  In the present embodiment, the heat radiating portion 40 is made of a composite material of metal and metal oxide, has a higher thermal conductivity than the varistor element body 10, and the surface 17 of the first element region 10 a of the varistor element body 10 and the heat. Therefore, the heat transmitted to the varistor V3 can be efficiently dissipated from the heat radiating unit 40.

  In the varistor V4 according to the third modified example shown in FIG. 8, the varistor element body 10 has a first element body area 10a and a second element body area 10b. In this case, it is preferable to dispose the insulating layer 55 in order to ensure the insulation of the heat radiating portion 40.

  In the varistor V5 according to the fourth modification shown in FIG. 9, the varistor element body 10 includes a first element body area 10a, a second element body area 10b, and a third element body area 10c. Yes. Here, the second element body region 10 b connects the first element body region 10 a and the third element region 10 c and is in contact with the first and second side surfaces 45 and 46 of the heat radiating portion 40. This is the area that was placed. Therefore, the first and second end surfaces 43 and 44 of the heat radiating portion 40 are exposed.

  Subsequently, the light emitting device LE according to the present embodiment will be described with reference to FIG. FIG. 10 is a schematic cross-sectional view showing the light emitting device according to this embodiment. The light emitting device LE includes, for example, the varistor V1 described above and the semiconductor light emitting element 61 electrically connected to the varistor V1. The light emitting device LE may include varistors V2 to V5 instead of the varistor V1.

  The semiconductor light emitting element 61 is a light emitting diode (LED) of a GaN (gallium nitride) semiconductor, and includes a substrate 62 and a layer structure LS formed on the substrate 62. GaN-based semiconductor LEDs are well known and will be described briefly. The substrate 62 is an optically transparent and electrically insulating substrate made of sapphire. The layer structure LS includes an n-type (first conductivity type) semiconductor region 63, a light emitting layer 64, and a p-type (second conductivity type) semiconductor region 65, which are stacked. The semiconductor light emitting element 61 emits light according to a voltage applied between the n-type semiconductor region 63 and the p-type semiconductor region 65.

  The n-type semiconductor region 63 includes an n-type nitride semiconductor. In the present embodiment, the n-type semiconductor region 63 is formed by epitaxially growing GaN on the substrate 62, and has an n-type conductivity by adding an n-type dopant such as Si. Further, the n-type semiconductor region 63 may have a composition that has a refractive index smaller than that of the light emitting layer 64 and a larger band gap. In this case, the n-type semiconductor region 63 serves as a lower cladding for the light emitting layer 64.

  The light-emitting layer 64 is formed on the n-type semiconductor region 63, and the carriers (electrons and holes) supplied from the n-type semiconductor region 63 and the p-type semiconductor region 65 are recombined to emit light in the light-emitting region. Is generated. The light emitting layer 64 can have, for example, a multiple quantum well (MQW) structure in which barrier layers and well layers are alternately stacked over a plurality of periods. In this case, the barrier layer and the well layer are made of InGaN, and the band gap of the barrier layer is configured to be larger than the band gap of the well layer by appropriately selecting the composition of In (indium). The light emitting region is generated in a region where carriers are injected in the light emitting layer 64.

  The p-type semiconductor region 65 includes a p-type nitride semiconductor. In the present embodiment, the p-type semiconductor region 65 is formed by epitaxially growing AlGaN on the light emitting layer 64, and has p-type conductivity by adding a p-type dopant such as Mg. The p-type semiconductor region 65 may have a composition that has a refractive index smaller than that of the light emitting layer 64 and a larger band gap. In this case, the p-type semiconductor region 65 serves as an upper cladding for the light emitting layer 64.

  A cathode electrode 66 is formed on the n-type semiconductor region 63. The cathode electrode 66 is made of a conductive material, and an ohmic contact with the n-type semiconductor region 63 is realized. An anode electrode 67 is formed on the p-type semiconductor region 65. The anode electrode 67 is made of a conductive material and realizes ohmic contact with the p-type semiconductor region 65. Bump electrodes 68 are formed on the cathode electrode 66 and the anode electrode 67. In the semiconductor light emitting device 61 having the above-described configuration, when a predetermined voltage is applied between the anode electrode 67 (bump electrode 68) and the cathode electrode 66 (bump electrode 68) and a current flows, the light emitting region 64 emits light. Luminescence will occur.

  The semiconductor light emitting element 61 is bump-connected to the second electrode portions 22 and 32. That is, the cathode electrode 66 is electrically and physically connected to the second electrode portion 22 via the bump electrode 68. The anode electrode 67 is electrically and physically connected to the second electrode portion 32 through the bump electrode 68. As a result, the varistor V1 is connected to the semiconductor light emitting element 61 in parallel. Therefore, the semiconductor light emitting element 61 is protected from the ESD surge by the varistor V1.

  In the light emitting device LE, since the semiconductor light emitting element 61 and the second electrode portions 22 and 32 of the varistor V1 are physically connected, the heat generated in the semiconductor light emitting element 61 causes the second electrode portions 22 and 32 to pass through. To the varistor V1. Since the varistor element body 10 and the heat radiating part 40 are thermally connected, the heat transmitted to the varistor V1 can be efficiently dissipated from the heat radiating part 40 as described above.

  The preferred embodiments of the present invention have been described above. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

  In the varistor V1 according to the present embodiment, the first and second electrodes 20 and 30 have the second electrode portions 22 and 32, but the varistors V3 to V5 according to the second to fourth modified examples. Thus, these second electrode portions 22 and 32 are not necessarily required.

  In the varistor V1 according to this embodiment, the insulating layer 50 is disposed on the varistor element body 10, but the insulating layer 50 is not always necessary. When the varistor V1 does not have the insulating layer 50, the second electrode portions 22 and 32 are unnecessary.

  In the varistor V1 according to the present embodiment, the heat radiating portion 40 is disposed so as to be thermally connected to the second main surface 12 of the varistor element body 10, but the present invention is not limited thereto. For example, the heat radiating part 40 may be thermally connected to any one of the surfaces 13 to 16 other than the second main surface 12 of the varistor element body 10.

In the varistor V1 according to the present embodiment, the varistor element body 10 is made of a semiconductor ceramic containing ZnO as a main component, but may be made of other semiconductor ceramics. For example, the varistor element body 10 may be composed of a semiconductor ceramic such as a composite perovskite varistor material or SiC varistor material in which SrTiO ₃ is a main component and a part of Sr is replaced with Ca, Ba or the like.

  In the present embodiment, an example in which a semiconductor light emitting element is used as an electronic element is shown, but the present invention is not limited to this. The present invention can be applied to electronic elements (for example, FETs, bipolar transistors, etc.) that generate heat during operation in addition to semiconductor light emitting elements.

  In the present embodiment, a light-emitting diode of a GaN-based semiconductor LED is used as the semiconductor light-emitting element 61, but is not limited thereto. As the semiconductor light emitting element 61, for example, a nitride semiconductor LED other than GaN-based (for example, InGaNAs-based semiconductor LED), a compound semiconductor LED other than nitride-based, or a laser diode (LD: Laser Diode) may be used. .

It is a schematic perspective view which shows the varistor which concerns on this embodiment. It is a schematic sectional drawing which shows the varistor concerning this embodiment. It is a schematic sectional drawing which shows the 1st modification of the varistor which concerns on this embodiment. It is a schematic sectional drawing which shows the 2nd modification of the varistor which concerns on this embodiment. It is a schematic plan view which shows the 2nd modification of the varistor which concerns on this embodiment. It is a figure which shows the cross-sectional structure along the VI-VI line in FIG. It is a figure which shows the cross-sectional structure along the VII-VII line in FIG. It is a schematic sectional drawing which shows the 3rd modification of the varistor which concerns on this embodiment. It is a schematic perspective view which shows the 4th modification of the varistor which concerns on this embodiment. It is a schematic sectional drawing which shows the light-emitting device concerning this embodiment.

Explanation of symbols

V1 to V5 ... Varistor, 10 ... Varistor element body, 11, 12 ... First and second main surfaces, 20 ... First electrode, 21 ... First electrode portion, 30 ... Second electrode, 31 ... First 1 electrode portion, 40 ... heat dissipation portion, 41, 42 ... first and second main surfaces, 43, 44 ... first and second end surfaces, 45, 46 ... first and second side surfaces, 61 ... semiconductor Light emitting element, LE ... Light emitting device.

Claims (16)

An element body that exhibits a voltage nonlinear characteristic and has a region including the first and second surfaces;
At least two electrodes each having an electrode portion disposed on the first surface of the region of the element body;
A heat dissipating part disposed so as to have a higher thermal conductivity than the region of the element body and to be thermally connected to the second surface of the region;
The radiator is made of a composite material of a metal and a metal oxide and electrically connected to the second surface of the region of the element body .   2. The varistor according to claim 1, wherein the heat dissipating part is disposed so as to contact the second surface of the region of the element body. The heat radiating portion includes a first surface facing the second surface of the region of the element body and a plurality of second surfaces not facing the second surface of the region of the element body. Contains
3. The varistor according to claim 1, wherein at least one of the plurality of second surfaces included in the heat radiating portion is exposed. The heat radiating portion includes a first surface facing the second surface of the region of the element body and a plurality of second surfaces not facing the second surface of the region of the element body. Contains
3. The varistor according to claim 1, wherein the metal is conductive from the first surface of the heat radiating portion to at least one of the plurality of second surfaces. The varistor according to any one of claims 1 to 4 , wherein the heat radiating portion contains Ag as a main component of the metal. The varistor according to any one of claims 1 to 5 , wherein the element body is made of the semiconductor ceramic. The element body includes ZnO as a main component,
The varistor according to claim 6 , wherein the heat radiating portion contains ZnO as the metal oxide. The varistor according to claim 6 or 7 , wherein the element body and the heat dissipation portion are formed by simultaneous firing. A light emitting device comprising a varistor and a light emitting element,
The varistor is
An element body that exhibits a voltage nonlinear characteristic and has a region including the first and second surfaces;
At least two electrodes each having an electrode portion disposed on the first surface of the region of the element body;
A heat dissipating part disposed so as to have a higher thermal conductivity than the region of the element body and to be thermally connected to the second surface of the region;
The region of the element body is made of a semiconductor ceramic,
The heat radiating portion is a metal and Rutotomoni such a composite material of metal oxide, Ri the second surface and are electrically connected up for the said region element has,
The light emitting device, wherein the light emitting element is electrically and physically connected to at least two of the electrodes so as to be connected in parallel to the varistor. The light-emitting device according to claim 9 , wherein the heat dissipating part is disposed so as to contact the second surface of the region of the element body. The heat radiating portion includes a first surface facing the second surface of the region of the element body and a plurality of second surfaces not facing the second surface of the region of the element body. Contains
11. The light emitting device according to claim 9, wherein at least one of the plurality of second surfaces included in the heat dissipation portion is exposed. The heat radiating portion includes a first surface facing the second surface of the region of the element body and a plurality of second surfaces not facing the second surface of the region of the element body. Contains
11. The light emitting device according to claim 9 , wherein the metal is conductive from the first surface of the heat radiating portion to at least one of the plurality of second surfaces. The light emitting device according to any one of claims 9 to 12 , wherein the heat radiating portion contains Ag as a main component of the metal. The light emitting device according to claim 9 , wherein the element body is made of the semiconductor ceramic. The element body includes ZnO as a main component,
The light-emitting device according to claim 14 , wherein the heat radiating portion contains ZnO as the metal oxide. The light emitting device according to claim 14, wherein the element body and the heat radiating portion are formed by simultaneous firing.

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