KR20080089218A - Varistor and light-emitting apparatus - Google Patents

Abstract

A varistor and a light-emitting apparatus are provided to improve manufacturing efficiency of the varistor by simultaneously sintering a varistor unit and a heat discharge unit. A varistor includes a varistor unit(11), a pair of external electrodes(12,13), and a heat discharging unit(14). The varistor has a varistor body(15) for representing a voltage non-linear characteristic and a pair of inner electrodes arranged to face each other by placing the varistor body therebetween. The external electrodes are connected to the inner electrodes and become a connection terminal of external device. The heat discharge unit is thermally connected to the varistor unit. A major component of the varistor body is ceramic and the heat discharge unit is made of composite material of metal and metal oxide.

Description

Varistor and light-emitting apparatus

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

A varistor comprising: a varistor element that exhibits voltage nonlinearity, a body having a pair of internal electrodes disposed inside the varistor element with a portion of the varistor element interposed therebetween, and formed on an outer surface of the element, There is a pair of terminal electrodes connected to the internal electrodes, respectively (see Japanese Laid-Open Patent Publication No. 2002-246207).

By the way, the varistor can be connected in parallel to an electronic device such as a semiconductor light emitting device or a field effect transistor (FET) to protect the electronic device from an ESD (electrostatic discharge) surge. This electronic element may generate heat during operation. When the electronic device becomes a high temperature, it causes deterioration of the characteristics of the device itself, affecting its operation. For this reason, it is necessary to dissipate the generated heat efficiently.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a varistor and a light emitting device capable of efficiently dissipating heat.

The inventors of the present invention have thought that by forming a metal in contact with the varistor element and dissipating heat transmitted to the varistor from the metal, heat can be efficiently dissipated from the varistor. However, when the metal and one surface of the outer side of the varistor element are brought into contact with each other, the bonding strength between the two is weak, and the varistor element and the metal may peel off. In this case, the heat transmitted from the metal part to the varistor cannot be radiated efficiently. Therefore, in order to solve this problem, the inventors have invented a varistor and a light emitting device in which the bonding strength between the metal and the varistor element is enhanced.

A varistor according to the present invention is a varistor element having a voltage nonlinear characteristic, a varistor portion having an internal electrode disposed so that at least a portion of the varistor element is opposed to each other, and connected to an internal electrode. And a heat dissipation portion thermally connected to the varistor portion, wherein the varistor element has a semiconductor ceramic as a main component, and the heat dissipation portion is made of a composite material of a metal and a metal oxide.

In addition, the varistor according to the present invention is a varistor element that exhibits voltage nonlinearity, an electrode portion disposed inside the varistor element, and an electrode portion disposed on the surface of the varistor element and at least partially opposed to the electrode portion. And a heat dissipation portion thermally connected to the varistor portion, wherein the varistor element has a semiconductor ceramic as a main component, and the heat dissipation portion is made of a composite material of a metal and a metal oxide.

In this varistor, the heat dissipation part contains a metal oxide like the varistor element whose main component is a semiconductor ceramic. By making the components of the varistor element and the heat dissipation part in common, the occurrence of cracks between the varistor part and the heat dissipation part during firing or the like is suppressed, and the joint strength of the varistor part and the heat dissipation part is sufficiently secured. As a result, the heat transferred from the external element to the varistor portion is efficiently radiated by the metal of the radiating portion.

Moreover, it is preferable that metal is conducting from the surface which contacts the varistor part in a heat radiating part to the surface which does not contact a varistor part. In this case, the efficiency of heat radiation by the heat radiating part becomes higher.

In addition, the metal oxide preferably contains ZnO. In this case, the occurrence of cracks between the varistor portion and the heat dissipation portion is more reliably suppressed when firing or the like, and the joint strength of the varistor portion and the heat dissipation portion is sufficiently secured.

In addition, the metal oxide preferably contains metal coated Al ₂ O ₃ . In this case, the heat dissipation path by the metal is easily formed in the heat dissipation portion, so that the efficiency of heat dissipation can be increased.

Moreover, it is preferable that metal has Ag as a main component. Ag diffuses into the grain boundary of ZnO, which is the main component of the varistor element, and thus can further increase the bonding strength of the varistor portion and the heat dissipation portion.

Moreover, it is preferable that the varistor part and the said heat radiating part are formed by simultaneous baking. In this case, the manufacturing process can be simplified.

In addition, the light emitting device according to the present invention is a light emitting device having a light emitting element and a varistor, the varistor is an interior disposed so that at least a portion of the varistor body facing each other with the varistor element expressing the voltage non-linear characteristics, and the varistor element therebetween A varistor having an electrode, an external electrode connected to the internal electrode and serving as a connection end of the light emitting element, and a heat dissipating unit arranged to contact the varistor unit, wherein the varistor element has ZnO as a main component, and the heat dissipating unit is composed of metal and metal. It is characterized by consisting of an oxide composite material.

In this light emitting device, the heat dissipation part contains a metal oxide, like a varistor element containing ZnO as a main component. Since the components of the varistor element and the heat dissipation part are made common, cracks are prevented between the varistor part and the heat dissipation part during firing or the like, and the joint strength of the varistor part and the heat dissipation part is sufficiently secured. As a result, heat transmitted to the varistor portion from the light emitting element via the external electrode is efficiently radiated by the metal of the heat radiating portion.

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

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of the varistor and the light-emitting device which concern on this invention is described in detail, referring drawings.

[First embodiment]

1 is a schematic perspective view of a varistor according to a first embodiment of the present invention. 2 is a schematic sectional view. 1 and 2, the varistor V1 has a substantially rectangular parallelepiped shape including a varistor portion 11, a pair of external electrodes 12 and 13, and a heat dissipation portion 14.

The varistor unit 11 includes a varistor element 15, a first internal electrode 16, a second internal electrode 17, and a third internal electrode 18. The varistor element 15 has a substantially rectangular parallelepiped shape, and faces 15a and 15b facing each other, and faces 15c and 15d facing each other perpendicularly to the faces 15a and 15b. And two surfaces facing and adjacent to the surface 15c and the surface 15d.

The varistor element 15 is a laminate formed by laminating a plurality of varistor layers. Each varistor layer is a part which expresses voltage nonlinearity, has ZnO as a main component, and contains Pr or Bi as a subcomponent. These subcomponents are present in the varistor layer as a single metal or an oxide. In the actual varistor V1, the boundaries between the plurality of varistor layers cannot be visually recognized.

The first internal electrode 16 and the second internal electrode 17 are disposed on the surface 15a of the varistor element 15. The first internal electrode 16 and the second internal electrode 17 have a rectangular shape when viewed in a direction perpendicular to the surface 15a, and are symmetrically arranged at intervals from each other. The first internal electrode 16 is not exposed to the surface 15c of the varistor element 15 and the two side surfaces adjacent to the surface 15c, and to an inner position from the edge of the surface 15a by a predetermined distance. Elongated Similarly, the second internal electrode 17 is not exposed to the surface 15d of the varistor element 15 and the two side surfaces adjacent to the surface 15d, and the inner side of the second internal electrode 17 is a predetermined distance from the edge of the surface 15a. It extends to the position.

The first internal electrode 16 and the second internal electrode 17 are covered with a glaze 19 mainly composed of glass, and are electrically insulated from each other. Openings 19a and 19b are formed in the glaze 19 at positions corresponding to the first internal electrode 16 and the second internal electrode 17. As a result, a part of the surfaces of the first internal electrode 16 and the second internal electrode 17 are exposed from the glaze 19.

The third internal electrode 18 is disposed approximately in the center of the varistor element 15 so as to face each other with each of the first internal electrode 16 and the second internal electrode 17 with a plurality of varistor layers interposed therebetween. It is arranged. The first internal electrode 16 and the second internal electrode 17 are electrically insulated from each other by the third internal electrode 18.

The external electrodes 12 and 13 are formed symmetrically on the outer surface of the glaze 19 so as to correspond to the first internal electrode 16 and the second internal electrode 17. The external electrodes 12 and 13 also extend into the openings 19a and 19b of the glaze 19 and are provided to the first internal electrode 16 and the second internal electrode 17 exposed from the glaze 19. I'm in contact. As a result, the external electrode 12 is electrically and physically connected to the first internal electrode 16, and the external electrode 13 is electrically and physically connected to the second internal electrode 17. The external electrodes 12 and 13 function as connection ends of external elements such as the semiconductor light emitting element 61 (see Fig. 7).

The heat dissipation portion 14 has a substantially rectangular parallelepiped shape like the varistor element 15 and faces 14c facing each other perpendicularly to the surfaces 14a and 14b and 14a and 14b facing each other. ) And face 14d and two opposite faces adjacent to face 14c and face 14d. The surface 14a of the heat dissipation part 14 is joined to the surface 15b of the varistor element 15.

The heat radiating part 14 is formed with the composite material of a metal and a metal oxide. Ag, Ag-Pd, Pd, etc. can be used as a metal here, For example, it is preferable to use Ag from a viewpoint of thermal conductivity. As the metal oxide, Al ₂ O ₃ , ZnO, SiO ₂ , and ZrO ₂ are used. Al ₂ O ₃ is used by Ag coating the particles of the metal oxide, for example by electroless plating. In addition, the metal oxide does not necessarily need to contain all of Al ₂ O ₃ , ZnO, SiO ₂ , and ZrO ₂ described above, and may be included at least one kind or more.

This heat radiating part 14 is formed by baking simultaneously with the varistor part 11, in the state which the surface 14a contacted the surface 15b of the varistor element 15. As shown in FIG. The inside of the heat dissipation part 14 is the surface 14b, the surface 14c, and the surface 14d which are not in contact with the varistor part 11 from the surface 14a which is in contact with the varistor part 11 by metal Ag. ) Is on. This conduction path is further established by Ag coated Al ₂ O ₃ .

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

First, the varistor material is adjusted by mixing ZnO, which is the main component of the varistor element 15, and a metal of Pr or Bi, which is a minor component, in a predetermined ratio. Next, an organic binder, an organic solvent, an organic plasticizer, and the like are added to this varistor material to obtain a slurry.

After apply | coating this slurry on a film, it is dried and a green sheet is obtained. Next, an electrode portion corresponding to the first internal electrodes 16 to the third internal electrodes 18 is formed in the green sheet. These electrode portions are formed by printing a conductive paste, in which an organic binder and an organic solvent are mixed with a metal powder containing Ag particles as a main component, on a varistor element and drying.

Next, the green sheet on which the electrode portion is formed and the green sheet on which the electrode portion is not formed are superimposed in a predetermined order to form a sheet stack. And the obtained sheet laminated body is cut | disconnected by a chip unit and the green body corresponding to the varistor part 11 is obtained. Thereafter, the green body is subjected to heat treatment at a temperature of, for example, 180 ° C. to 400 ° C. for about 0.5 hour to 24 hours, thereby performing a binder removal treatment.

Next, prepare the heat radiating unit 14 composed of a composite material of Ag, Al ₂ O _3, ZnO, SiO _2, and ZrO _2. The above-described green body is superimposed on the surface 14a of the heat dissipation unit 14 and fired simultaneously at a temperature of 800 ° C. or higher in air or in an O ₂ atmosphere. Thereby, the junction body of the varistor part 11 and the heat radiating part 14 is formed. After obtaining the bonded body, the glaze 19 is printed to cover the first internal electrode 16 and the second internal electrode 17, and the external electrodes to block the openings 19a and 19b of the glaze 19. The electrode portion corresponding to (12, 13) is printed.

This electrode portion is formed by printing on a glaze 19 and drying a conductive paste in which an organic binder and an organic solvent are mixed with a metal powder composed mainly of Au particles or Ag particles. By simultaneously baking this at a temperature of 800 ° C. or higher in an O ₂ atmosphere, external electrodes 12 and 13 are formed, and varistor V1 shown in FIGS. 1 and 2 is completed.

In this varistor V1, the heat dissipation unit 14 contains a component such as ZnO as a main component of the varistor element 15 as a metal oxide, and the components of the varistor element 15 and the heat dissipation unit 14 are common. . At the time of firing, Ag contained in the heat dissipation portion 14 diffuses to the grain boundary of ZnO, which is the main component of the varistor element 15, in the vicinity of the interface between the face 14a and the face 15b. Thereby, the varistor part 11 and the heat radiating part 14 are firmly joined.

For this reason, in varistor V1, the crack does not generate | occur | produce between the varistor part 11 and the heat dissipation part 14 at the time of baking (or debinding | bonding), and the joining of the varistor part 11 and the heat dissipation part 14 is performed. Enough strength is secured. Accordingly, the heat transferred from the external element through the external electrodes 12 and 13 to the varistor portion 11 is transferred from the surface 14a to the surface 14b of the heat radiating portion 14 by the Ag particles and the coated portion of Al ₂ O ₃ . ), The heat radiation is efficiently conducted along the conduction path formed over the surface 14c and the surface 14d.

In the varistor V1, the varistor portion 11 and the heat radiating portion 14 are simultaneously fired. This realizes the simplification of the manufacturing process, contributing to the improvement of the manufacturing efficiency of the varistor V1 and the cost reduction.

Second Embodiment

The varistor which concerns on 2nd Embodiment of this invention is demonstrated. 3 is a schematic sectional view showing a varistor according to a second embodiment of the present invention. The varistor V2 shown in FIG. 3 differs from the varistor V1 according to the first embodiment in the configuration of the internal electrode.

That is, the varistor V2 does not include the third internal electrode 18 (refer to FIG. 2), and instead, the first internal electrode 21 disposed in the varistor element 15 so that one end side thereof faces each other and It has the second internal electrode 22. The first internal electrode 21 and the second internal electrode 22 are connected to the external electrodes 12, 13 by the through conductor 23, respectively.

Also in this varistor V2, the varistor element 15 has ZnO as its main component, and the heat dissipation portion 14 is made of a composite material of a metal oxide containing Ag, which is a metal, and ZnO, which is a main component of the varistor element 15. Formed. Therefore, as in the first embodiment, the bonding strength between the varistor portion 11 and the heat dissipation portion 14 is sufficiently secured, and the heat transferred from the external element to the varistor portion 11 through the external electrodes 12 and 13 is dissipated. The heat radiation is efficiently conducted along the conduction path formed from the surface 14a to the surface 14b, the surface 14c, and the surface 14d of the portion 14.

[Third Embodiment]

The varistor which concerns on 3rd Embodiment of this invention is demonstrated. 4 is a schematic cross-sectional view showing a varistor according to a third embodiment of the present invention. The varistor V3 shown in FIG. 4 has the varistor according to the second embodiment in that the glaze 31 is formed on the side of the surface 14b which is not in contact with the varistor portion 11 in the heat dissipation portion 14. More different than (V2).

Also in the varistor V3, the varistor element 15 has ZnO as its main component, and the heat dissipation unit 14 is made of a composite material of a metal oxide containing Ag, which is a metal, and ZnO, which is a main component of the varistor element 15. Formed. Therefore, the bonding strength between the varistor part 11 and the heat dissipation part 14 is sufficiently secured, and the heat transferred from the external element to the varistor part 11 through the external electrodes 12 and 13 is the surface of the heat dissipation part 14. The heat radiation is conducted efficiently along the conduction path formed over the surface 14b, the surface 14c, and the surface 14d from 14a.

Fourth Embodiment

The varistor which concerns on 4th Embodiment of this invention is demonstrated. 5 is a schematic cross-sectional view showing a varistor according to a fourth embodiment of the present invention. In the varistor V4 shown in FIG. 5, the external electrodes 41 and 42 are formed on the outer surface of the glaze 31 formed on the side of the surface 14b which is not in contact with the varistor portion 11. Is further different from the varistor V3 according to the third embodiment.

In the varistor V4, one external electrode 12 formed on the varistor portion 11 side, the first internal electrode 21, and one external electrode 41 formed on the heat dissipation portion 14 side are formed through through electrodes ( 43, the other external electrode 13 formed on the varistor portion 11 side, the second internal electrode 22, and the other external electrode formed on the heat dissipating portion 14 side ( 42 is connected by the penetrating electrode 44. Further, electrically insulating layers 45 are formed around the through electrodes 43 and 44 passing through the heat radiating portion 14, respectively.

Also in this varistor V4, the varistor element 15 has ZnO as its main component, and the heat dissipating portion 14 is made of a composite material of a metal oxide containing Ag, which is a metal, and ZnO, which is a main component of the varistor element 15. Formed. Therefore, the bonding strength between the varistor part 11 and the heat dissipation part 14 is sufficiently secured, and the heat transferred from the external element to the varistor part 11 through the external electrodes 12 and 13 is the surface of the heat dissipation part 14. The heat dissipation is performed efficiently along the conduction path formed from 14a to 14c and 14d.

In the varistor V4, the external electrodes 12, 13 formed on the side of the varistor 11 may be connected to the external elements, and the external electrodes 41, 42 formed on the heat dissipating portion 14 side are externally connected. It may be a connection end of the device.

[Fifth Embodiment]

The varistor which concerns on 5th Embodiment of this invention is demonstrated. 6 is a schematic perspective view showing a varistor according to a fifth embodiment of the present invention. In the varistor V5 shown in FIG. 6, the structure of the varistor part 50 differs from each said embodiment. That is, the varistor V5 includes a first internal electrode 52 and a second internal electrode 53, a first heat dissipation unit 54, and a second heat dissipation unit 55 in the varistor element 51. . In addition, external electrodes 56 and 57 are provided on one surface 51a of the varistor element 51.

The first internal electrode 52 and the second internal electrode 53 are formed on the plate portions 52a and 53a, and one surface 51a of the varistor element 51 from one end of the plate portions 52a and 53a. It has the connection members 52b and 53b which protrude toward the other surface 51b, respectively. The first internal electrode 52 and the second internal electrode 53 are arranged with a plurality of varistor layers interposed therebetween so that the connection members 52b and 53b are located on opposite sides, and most of the flat plate portions 52a and 53a are disposed. Are opposed to each other. One tip portion of the connecting members 52b and 53b is drawn out to be exposed to the surface 51a of the varistor element 51, and the other tip portion is drawn out to be exposed to the surface 51b.

The first heat dissipation unit 54 and the second heat dissipation unit 55 have a plate shape thicker than the first internal electrodes 52 and the second internal electrodes 53, and the first internal electrodes 52 and the second internal electrodes ( 53) and are arranged substantially parallel to each other. The surfaces 54a and 54b in the width direction of the first heat dissipation unit 54 are exposed to the surfaces 51a and 51b in the varistor element 51, respectively, and the end surfaces 54c and 54d in the longitudinal direction are varistors. In the elementary body 51, the surface 51a and the surface 51d which are mutually perpendicular to the surface 51a and the surface 51b are exposed, respectively.

Similarly, the surfaces 55a and 55b in the width direction of the second heat dissipation unit 55 are exposed to the surfaces 51a and 51b in the varistor element 51, respectively, and the end surfaces 55c and 55d in the longitudinal direction. The silver varistor element 51 is exposed to the surface 51c and the surface 51d which face each other perpendicular to the surface 51a and the surface 51b, respectively.

The external electrodes 56 and 57 of the varistor element 51 intersect the first internal electrode 52, the second internal electrode 53, the first heat dissipation part 54, and the second heat dissipation part 55. In the surface 51a, it is formed along the edge part of the surface 51c side, and the edge part of the surface 51d side, respectively. The external electrode 56 is electrically and physically connected to the connection member 53b of the second internal electrode 53, the first heat dissipation part 54, and the second heat dissipation part 55, and the external electrode 57 is The connection member 52b of the first internal electrode 52, the first heat dissipation unit 54, and the second heat dissipation unit 55 are electrically and physically connected.

In addition, on the surface 51a of the varistor element 51, the pad electrodes 58 are arranged in a matrix form of, for example, three rows by four columns between the external electrodes 56 and 57. Among the pad electrodes 58, the pad electrodes 58 corresponding to the outer rows (first and fourth rows) are in contact with the first heat dissipation unit 54 and the second heat dissipation unit 55.

Also in this varistor V5, the varistor element 51 has ZnO as a main component, and the first heat dissipation unit 54 and the second heat dissipation unit 55 are Ag, which is a metal, and ZnO as a main component of the varistor element 51. It is formed of a composite material of a metal oxide comprising a. Therefore, the bonding strength of the varistor part 50, the 1st heat dissipation part 54, and the 2nd heat dissipation part 55 is fully ensured, and it is received from an external element through the external electrodes 56 and 57 and the pad electrode 58. As shown in FIG. The heat transmitted to the varistor part 50 is conducted from the surface 54a to the surface 54b, the surface 54c, and the surface 54d of the first heat dissipation portion 54, and the second heat dissipation portion ( The heat dissipation is efficiently performed along the conduction path formed from the surface 55a to the surface 55b, the surface 55c, and the surface 55d at 55.

[Light emitting device]

Subsequently, a light emitting device according to one embodiment of the present invention will be described. 7 is a schematic cross-sectional view showing a light emitting device according to one embodiment of the present invention. The light emitting device LE shown in FIG. 7 includes, for example, the varistor V1 described above and a semiconductor light emitting element 61 electrically connected to the varistor V1.

The semiconductor light emitting element 61 is a light emitting diode (LED) of a GaN (gallium nitride) -based semiconductor, and includes a substrate 62 and a layer structure LS formed on the substrate 62. GaN-based semiconductor LEDs are well known and simplify their description. The substrate 62 is an optically transparent and electrically insulating substrate made of sapphire. The layer structure LS includes a stacked n-type (first conductivity type) semiconductor region 63, a light emitting layer 64, and a p-type (second conductivity type) semiconductor region 65. The semiconductor light emitting element 61 emits light in accordance with the 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. For example, an n-type dopant such as Si is added to have n-type conductivity. The n-type semiconductor region 63 may have a composition in which the refractive index is smaller than that of the light emitting layer 64 and the band gap is larger. In this case, the n-type semiconductor region 63 functions as a lower clad with respect to the light emitting layer 64.

The light emitting layer 64 is formed on the n-type semiconductor region 63, and carriers (electrons and holes) supplied from the n-type semiconductor region 63 and the p-type semiconductor region 65 are recombined in the light emitting region. Generates light. The light emitting layer 64 may have, for example, a multiple quantum well (MQW) structure in which a barrier layer and a well layer are alternately stacked over a plurality of cycles. In this case, the barrier layer and the well layer are made of InGaN, and by appropriately selecting the composition of In (indium), the band gap of the barrier layer is configured to be larger than the band gap of the well layer. The light emitting region is formed in the region in which the carrier is 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. For example, p-type dopants such as Mg are added to have p-type conductivity. In addition, the p-type semiconductor region 65 may have a composition having a smaller refractive index and a larger band gap than the light emitting layer 64. In this case, the p-type semiconductor region 65 serves as the upper cladding with respect to the light emitting layer 64.

The cathode electrode 66 is formed on the n-type semiconductor region 63. The cathode electrode 66 is made of a conductive material, and ohmic contact is realized between the n-type semiconductor regions 63. An anode electrode 67 is formed on the p-type semiconductor region 65. The anode electrode 67 is made of a conductive material, and ohmic contact is realized between the p-type semiconductor regions 65. A bump electrode 68 is formed on the cathode electrode 66 and the anode electrode 67.

In the semiconductor light emitting element 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 layer 64 Light emission is generated in the light emitting area of?).

The semiconductor light emitting element 61 is bump-connected to the external electrodes 12 and 13. That is, the cathode electrode 66 is electrically and physically connected to the external electrode 12 through the bump electrode 68. The anode electrode 67 is electrically and physically connected to the external electrode 13 through the bump electrode 68. As a result, the varistor V1 is connected in parallel to the semiconductor light emitting element 61. Therefore, the varistor V1 protects the semiconductor light emitting element 61 from an ESD surge.

As described above, in the varistor V1, the heat dissipation unit 14 contains a component such as ZnO, which is a main component of the varistor element 15, as a metal oxide, and constitutes the components of the varistor element 15 and the heat dissipation unit 14. Is common. At the time of firing, Ag contained in the heat dissipation portion 14 diffuses to the grain boundary of ZnO, which is the main component of the varistor element 15, in the vicinity of the interface between the face 14a and the face 15b. Thereby, the varistor part 11 and the heat radiating part 14 are firmly joined.

Therefore, in the light emitting device LE, the heat transferred from the semiconductor light emitting element 61 to the varistor portion 11 through the external electrodes 12 and 13 is transferred to the heat dissipation portion 14 by the Ag particles and the coating portion of Al ₂ O ₃ . The heat radiation is efficiently conducted along the conduction path formed from the surface 14a to the surface 14b, the surface 14c, and the surface 14d.

[Sixth Embodiment]

The varistor which concerns on 6th Embodiment of this invention is demonstrated. 8 is a schematic sectional view showing a varistor according to a sixth embodiment of the present invention. The varistor V6 shown in FIG. 8 differs from the varistor V1 according to the first embodiment in that a plurality of first internal electrodes, second internal electrodes, and third internal electrodes are disposed.

That is, the varistor V6 has a first internal electrode 81A and a second internal electrode 82A symmetrically arranged at intervals from each other on the surface 15a of the varistor element 15, like the varistor V1. At the same time, the third internal electrode (approximately centered in the varistor element 15) faces each other with each of the first internal electrode 81A and the second internal electrode 82A with a plurality of varistor layers interposed therebetween ( 83A).

In the varistor element 15, the same position as that of the first internal electrode 81A, the second internal electrode 82A, and the third internal electrode 83A on the heat dissipation portion 14 side than the third internal electrode 83A. In this manner, the first internal electrodes 81B to 81D, the second internal electrodes 82B to 82D, and the third internal electrodes 83B to 83C are disposed. The first internal electrodes 81A to 81D are electrically connected to each other by the through electrodes 84, and the second internal electrodes 82A to 82D are electrically connected to each other by the through electrodes 85.

Also in this varistor V6, the varistor element 15 has ZnO as its main component, and the heat dissipation portion 14 is made of a composite material of a metal oxide containing Ag, which is a metal, and ZnO, which is a main component of the varistor element 15. Formed. Therefore, the bonding strength between the varistor part 11 and the heat dissipation part 14 is sufficiently secured, and the heat transferred from the external element to the varistor part 11 through the external electrodes 12 and 13 is the surface of the heat dissipation part 14. The heat dissipation is performed efficiently along the conduction path formed from 14a to 14c and 14d.

[Seventh Embodiment]

The varistor which concerns on 7th Embodiment of this invention is demonstrated. 9 is a schematic sectional view showing a varistor according to a seventh embodiment of the present invention. The varistor V7 illustrated in FIG. 9 differs from the varistor V2 according to the second embodiment in that a plurality of first internal electrodes and a plurality of second internal electrodes are disposed.

That is, the varistor V7 does not have the third internal electrode 18 (refer to FIG. 2) like the varistor V2, and instead, the first varistor V15 is disposed in the varistor element 15 so that one end side thereof faces each other. The internal electrode 91A and the second internal electrode 92A are provided. Further, in the varistor element 15, the heat dissipation portion 14 side of the varistor element 15 has the same positional relationship as the first internal electrodes 91A and the second internal electrodes 92A, and the first internal electrodes 91A. 91B and 91C and second internal electrodes 92B and 92C are disposed. The first internal electrodes 91A to 91C are connected to the external electrode 12 by the through electrode 93, and the second internal electrodes 92A to 92C are connected to the external electrode 13 by the through electrode 94. Is connected to.

Also in this varistor V7, the varistor element 15 has ZnO as its main component, and the heat dissipation portion 14 is made of a composite material of a metal oxide containing Ag, which is a metal, and ZnO, which is a main component of the varistor element 15. Formed. Therefore, the joint strength between the varistor part 11 and the heat dissipation part 14 is sufficiently secured, and the heat transferred from the external element to the varistor part 11 through the external electrodes 12 and 13 is transferred to the heat dissipation part 14. The heat dissipation is efficiently performed along the conduction path formed from the surface 14a to the surface 14b, the surface 14c, and the surface 14d.

This invention is not limited to the said embodiment. In each of the above embodiments, ZnO is exemplified as a semiconductor ceramic which is a main component of the varistor element 15. However, in addition to ZnO, SrTiO ₃ , BaTiO ₃ , SiC, or the like may be used as the semiconductor ceramic.

In addition, the varistor part 11 and the heat radiating part 14 may be joined by adhesion | attachment. Nitride-based semiconductor LEDs other than GaN-based semiconductors such as InGaNAs-based semiconductor LEDs may be connected to the varistors V1 to V7, or semiconductor LEDs or LDs other than nitride-based semiconductors may be connected. Not only LED but also various electronic elements which generate | occur | produce during operation | movement, such as a field effect transistor (FET) and a bipolar transistor, may be connected.

1 is a schematic perspective view showing a varistor according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of the varistor shown in FIG. 1. FIG.

3 is a schematic cross-sectional view showing a varistor according to a second embodiment of the present invention.

4 is a schematic sectional view showing a varistor according to a third embodiment of the present invention.

5 is a schematic sectional view showing a varistor according to a fourth embodiment of the present invention.

6 is a schematic perspective view showing a varistor according to a fifth embodiment of the present invention.

Fig. 7 is a schematic sectional view showing a light emitting device according to one embodiment of the present invention.

8 is a schematic sectional view showing a varistor according to a sixth embodiment of the present invention.

9 is a schematic sectional view showing a varistor according to a seventh embodiment of the present invention.

Claims (13)

A varistor element having a varistor element expressing a voltage non-linear characteristic, and an internal electrode disposed so that at least a portion thereof faces each other with the varistor element interposed therebetween; An external electrode connected to the internal electrode and serving as a connection end of an external element; A heat dissipation unit thermally connected to the varistor unit, The varistor element has a semiconductor ceramic as a main component, and the heat dissipation unit is a varistor, characterized in that the composite material of a metal and a metal oxide. A varistor element having a varistor element expressing voltage nonlinearity, an electrode portion disposed inside the varistor element, and a varistor portion disposed on a surface of the varistor element and at least partially opposed to the electrode portion; A heat dissipation unit thermally connected to the varistor unit, The varistor element has a semiconductor ceramic as a main component, and the heat dissipation unit is a varistor, characterized in that the composite material of a metal and a metal oxide. The method according to claim 1 or 2, And the metal is conductive from the surface in contact with the varistor portion in the heat dissipation portion to the surface not in contact with the varistor portion. The method according to claim 1 or 2, The metal oxide contains ZnO, Varistor, characterized in that. The method of claim 3, wherein The metal oxide contains ZnO, Varistor, characterized in that. The method according to claim 1 or 2, The metal oxide is a varistor, characterized in that it comprises a metal coated Al ₂ O ₃ . The method of claim 3, wherein The metal oxide is a varistor, characterized in that it comprises a metal coated Al ₂ O ₃ . The method according to claim 1 or 2, The metal is a varistor, characterized in that the main component as Ag. The method of claim 3, wherein The metal is a varistor, characterized in that the main component as Ag. The method of claim 4, wherein The metal is a varistor, characterized in that the main component as Ag. The method of claim 5, wherein The metal is a varistor, characterized in that the main component as Ag. The method according to claim 1 or 2, The varistor portion and the heat dissipation portion are formed by simultaneous firing, the varistor. A light emitting device having a light emitting element and a varistor, The varistor is A varistor element having a varistor element expressing a voltage non-linear characteristic, and an internal electrode disposed so that at least a portion thereof faces each other with the varistor element interposed therebetween; An external electrode connected to the internal electrode and serving as a connection end of the light emitting element; A heat dissipation unit disposed to contact the varistor unit, The varistor element has ZnO as a main component, and the heat dissipation unit is made of a composite material of a metal and a metal oxide.

Images