TWI581468B - Light emitting diode, light emitting device and method of fabricating the same - Google Patents

Description

Light-emitting diode, light-emitting device and manufacturing method thereof

The present invention relates to a light-emitting diode that improves heat dissipation efficiency and a method of manufacturing the same, and more particularly to a light-emitting diode having a structure including a heat-dissipating electrode and capable of effectively dissipating heat, and a method of manufacturing the same.

The light-emitting diode is an inorganic semiconductor element capable of emitting light generated by recombination of electrons and holes, and is divided into a horizontal light-emitting diode and an upright light-emitting diode according to an electrode arrangement position or a manner in which the electrode is connected to an external lead. A polar body or a flip-chip light emitting diode or the like.

Recently, as the demand for high-power light-emitting diodes has increased, the demand for large-area flip-chip light-emitting diodes having high heat dissipation efficiency has also soared. The electrode of the flip-chip light-emitting diode is directly bonded to the secondary substrate, and since it does not use a wire, the heat dissipation efficiency is very high compared with the horizontal light-emitting diode. Therefore, even if the high-density current is turned on, heat can be efficiently conducted to the secondary substrate side, and the flip-chip light-emitting diode is high. Power LEDs are the most suitable.

As the secondary substrate on which the flip-chip light-emitting diode is mounted, a substrate containing a metal is generally used. 1(a) and 1(b) show a secondary substrate on which a conventional flip-chip type light-emitting diode is mounted, and a light-emitting device including the same.

The light-emitting device shown in FIG. 1(a) includes a structure in which a flip-chip light-emitting diode is mounted on a secondary substrate 20 including a first pedestal 23 and a second pedestal 25 which are separated and insulated by an insulator 21. body. The light emitting diode includes a light emitting structure 11 and a first electrode 13 and a second electrode 15 which are formed to extend toward a lower portion of the light emitting structure 11. At this time, the first electrode 13 and the second electrode 15 contact the first pedestal 23 and the second pedestal 25, respectively, so that the light emitting diodes are mounted on the substrate 20.

According to the light-emitting device of FIG. 1(a), since the light-emitting structure 11 directly contacts the first pedestal 23 and the second pedestal 25 of the secondary substrate 20 by the first electrode 13 and the second electrode 15, the light-emitting structure 11 is caused. The generated heat can be released to the susceptor by the first electrode 13 and the second electrode 15. However, since the heat generated by the light-emitting structure 11 can be released only by the first electrode 13 and the second electrode 15, the heat dissipation thereof is limited. Further, the first electrode 13 and the second electrode 15 also need to perform an electrical function at the same time, and there is a limitation in the cross-sectional area of the first electrode 13 and the second electrode 15 in contact with the light-emitting structure 11, and in particular, in a light-emitting device driven at a high current, it is not possible to sufficiently dissipate heat to the outside.

The light-emitting device of FIG. 1(b) includes a structure in which a flip-chip light-emitting diode is mounted on a secondary substrate 30, the secondary substrate 30 including an insulating layer 31 coated on a susceptor 37, and the insulating layer The first conductive pattern 33 and the second conductive pattern 35 are insulated from each other on the layer 31. According to the light-emitting device of FIG. 1(b), the insulating layer 31 is coated on the susceptor 37 for heat dissipation, so that heat generated by the light-emitting diode is not efficiently transmitted to the susceptor 37 due to the insulating layer 31. Therefore, the heat dissipation efficiency of the light emitting diode is lowered.

Further, in the conventional light-emitting device, in order to improve the heat dissipation efficiency of the light-emitting diode, a method of forming a relatively increased electrode area is employed. However, in order to mount the first electrode and the second electrode of the light-emitting diode on the secondary substrate, solder bonding is generally performed. However, the larger the area of the electrode, the higher the probability of occurrence of a circuit short circuit during solder bonding. Therefore, there is a possibility that the light-emitting device is defective and the reliability is lowered.

Accordingly, there is a need for a light emitting diode having a structure capable of effectively releasing heat generated by a flip chip type light emitting diode, a secondary substrate, and a light emitting device including the same, and a light emitting device manufacturing method capable of preventing a short circuit of the circuit.

The technical problem to be solved by the present invention is to provide a light-emitting diode with improved heat dissipation efficiency and a light-emitting device including the same.

Another technical problem to be solved by the present invention is to provide a method for manufacturing a light-emitting device that improves heat dissipation efficiency by a simplified process.

A light emitting device according to an aspect of the present invention includes: a light emitting diode and a substrate, the substrate including a base and a conductive pattern on the base, and the substrate is attached to the light emitting diode, The light emitting diode includes: a light emitting structure including a first conductive type semiconductor layer, an active layer under the first conductive type semiconductor layer, and a second conductive layer under the active layer a semiconductor layer; a region partially removing the active layer and the second conductive semiconductor layer to partially expose a lower surface of the first conductive semiconductor layer; and an electrode layer located in the second conductive semiconductor layer Underside the ohmic contact; the first gold a genus layer that forms an ohmic contact with the first conductive type semiconductor layer through a region where the first conductive type semiconductor layer is exposed; a first insulating layer partially covering the first metal layer and the electrode layer a first bump and a second bump, which are located at a lower portion of the light emitting structure and are in contact with the conductive pattern, wherein the first bump and the second bump are respectively associated with the first metal layer and Electrically connecting the electrode layer; and a heat dissipating electrode located at a lower portion of the light emitting structure and in contact with the base and electrically insulated from the light emitting structure; wherein the first conductive type semiconductor layer is partially exposed The region includes a plurality of holes exposing the first conductive semiconductor layer and at least one connection hole connecting the holes, and the first bump, the second bump, and the heat dissipation electrode are spaced apart from each other, and the heat dissipation The thermal conductivity of the electrode is higher than the thermal conductivity of the first bump and the second bump.

Therefore, it is possible to provide a light-emitting device with improved heat dissipation efficiency.

The light emitting diode may further include an insulating material portion covering the first bump, the second bump, and the side surface of the heat dissipation electrode.

The lower surface of the insulating material portion, the lower surface of the first bump, the lower surface of the second bump, and the lower surface of the heat dissipating electrode may be formed side by side at the same height.

The pedestal may include a protrusion, and an upper surface of the protrusion, an upper surface of the metal pattern may be formed side by side at the same height.

The first bump, the second bump, and the heat dissipation electrode may include solder.

The heat dissipation electrode may be located between the first bump and the second bump.

In addition, the conductive pattern may include a first conductive pattern in contact with the first bump and a second conductive pattern in contact with the second bump, The pedestal may include a protrusion between the first and second conductive patterns.

The light emitting diode may further include an insulating layer between the light emitting structure and the heat dissipation electrode.

The first and second bumps may be directly bonded to the conductive pattern.

In some embodiments, an insulating pattern between the susceptor and the conductive pattern may also be included, and the pedestal and the conductive pattern may comprise a metal.

The electrode layer may be formed in a single body.

The first bump and the second bump may be in direct contact with a portion of the first metal layer and a portion of the electrode layer, respectively.

A light emitting diode according to another aspect of the present invention includes: a light emitting structure including a first conductive type semiconductor layer, an active layer under the first conductive type semiconductor layer, and a portion located under the active layer a second conductive type semiconductor layer; a region partially removing the active layer and the second conductive type semiconductor layer to partially expose a lower surface of the first conductive type semiconductor layer; and an electrode layer located at the second conductive type Forming an ohmic contact under the semiconductor layer; a first metal layer forming an ohmic contact with the first conductive type semiconductor layer through a region where the first conductive type semiconductor layer is exposed; the first insulating layer partially covering The first metal layer and the electrode layer; the first bump and the second bump are located at a lower portion of the light emitting structure and electrically connected to the first metal layer and the electrode layer, respectively; a heat dissipating electrode located at a lower portion of the light emitting structure and electrically insulated from the light emitting structure; wherein a region where the first conductive type semiconductor layer is partially exposed includes the first conductive A plurality of apertures and at least one connection hole connecting the holes of the semiconductor layer is exposed, and the first bump and the second bump electrodes spaced cooling, the The thermal conductivity of the heat dissipating electrode is higher than the thermal conductivity of the first and second bumps.

The light emitting diode may further include an insulating material portion covering the first bump, the second bump, and the side surface of the heat dissipation electrode.

The first bump, the second bump, and the heat dissipation electrode may include solder.

The light emitting diode further includes an insulating layer between the light emitting structure and the heat dissipating electrode.

The heat dissipation electrode may be located between the first bump and the second bump.

A method of fabricating a light emitting device according to another aspect of the present invention includes: mounting a light emitting diode on a substrate, the substrate including a base and a conductive pattern on the base, wherein the light emitting diode includes An illuminating structure comprising a first conductive semiconductor layer, an active layer under the first conductive semiconductor layer, and a second conductive semiconductor layer under the active layer; partially removing the active layer and a second conductive type semiconductor layer to partially expose a lower surface of the first conductive type semiconductor layer; an electrode layer located under the second conductive type semiconductor layer and forming an ohmic contact; the first metal layer, Passing through a region exposed by the first conductive type semiconductor layer and forming an ohmic contact with the first conductive type semiconductor layer; a first insulating layer partially covering the first metal layer and the electrode layer; a bump and a second bump located at a lower portion of the light emitting structure and in contact with the conductive pattern, wherein the first bump and the second bump respectively correspond to the first gold The layer and the electrode layer are electrically connected; and a heat dissipating electrode is located at a lower portion of the light emitting structure and in contact with the pedestal; wherein a region where the first conductive semiconductor layer is partially exposed includes the a plurality of holes exposed by a conductive semiconductor layer and at least one connection hole connecting the holes, and the first bumps, the second bumps, and the The heat dissipating electrodes are spaced apart from each other, and the heat dissipating electrode has higher thermal conductivity than the first bump and the second bump.

The light emitting diode may further include an insulating material portion covering the first bump, the second bump, and a side surface of the heat dissipation electrode.

Mounting the light emitting diode on the substrate includes: arranging the light emitting diode in a predetermined area of the substrate, provided that the first bump, the second bump, and the heat dissipating electrode are in contact with the substrate Heating the first bump, the second bump, and the heat dissipation electrode to a temperature above the melting point of the solder; and cooling the solder.

The pedestal may include a protrusion, the first bump and the second bump are disposed on the conductive pattern, and the heat dissipation electrode may be disposed on the protrusion.

The upper surface of the protrusion and the upper surface of the conductive pattern may be formed side by side at the same height.

The substrate may further include an insulating pattern between the conductive pattern and the susceptor, and the conductive pattern and the pedestal may include a metal.

The light emitting diode further includes an insulating layer between the light emitting structure and the heat dissipating electrode.

According to the present invention, there is provided a light-emitting diode which improves heat dissipation efficiency by including a heat-dissipating electrode having a relatively high thermal conductivity, and a light-emitting device including the same. In addition, since the plurality of bumps and the heat-dissipating electrode solder are included, the manufacturing process of the light-emitting device can be simplified, and the reliability of the manufactured light-emitting device can be improved.

11‧‧‧Lighting structure

13‧‧‧First electrode

15‧‧‧second electrode

20‧‧‧Substrate

21‧‧‧Insulator

23‧‧‧First base

25‧‧‧Second base

30‧‧‧Substrate

31‧‧‧Insulation

33‧‧‧First conductive pattern

35‧‧‧Second conductive pattern

37‧‧‧Base

100‧‧‧Lighting diode

100a‧‧‧Lighting diode

100b‧‧‧Lighting diode

120‧‧‧Lighted structure

120a‧‧ hole

120b‧‧‧connection hole

121‧‧‧First Conductive Semiconductor Layer

123‧‧‧Active layer

125‧‧‧Second conductive semiconductor layer

130‧‧‧electrode layer

131‧‧‧Second electrode

140‧‧‧First metal layer

141‧‧‧First electrode

150‧‧‧Insulation

150'‧‧‧Insulation

151‧‧‧First insulation

151a‧‧‧First opening

151b‧‧‧second opening

153‧‧‧Second insulation

153a‧‧‧3rd opening

153b‧‧‧fourth opening

161‧‧‧First bump

163‧‧‧second bump

170‧‧‧heating electrode

180‧‧‧Inserts Division

200‧‧‧Substrate

210‧‧‧Base

220‧‧‧Insulation pattern

230‧‧‧Electrical pattern

A-A, B-B‧‧ lines

R‧‧‧Rough surface

1(a) and 1(b) are cross-sectional views for explaining a conventional light-emitting device.

Figure 2 is a cross-sectional view for explaining a light-emitting device according to an embodiment of the present invention.

Figure 3 is a cross-sectional view for explaining a method of manufacturing a light-emitting device according to another embodiment of the present invention.

Figure 4 is a cross-sectional view for explaining a light-emitting diode according to another embodiment of the present invention.

5(a) and 5(b) to 7 are a plan view and a cross-sectional view for explaining a light-emitting diode according to another embodiment of the present invention.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The embodiments described below are provided as examples in order to fully convey the idea of the present invention to those skilled in the art to which the invention pertains. Therefore, the present invention is not limited to the embodiments described below, and may be embodied in other forms. Moreover, in the drawings, the width, length, thickness, and the like of the structural elements may be exaggerated for convenience. In addition, when it is described that one structural element is "upper" or "above" other structural elements, it includes not only the "tight upper portion" or "tightly" portion of the other portions, but also the various structural elements and others. There are also other structural elements between structural elements. Throughout the specification, the same reference symbols represent the same structural elements.

Figure 2 is a cross-sectional view for explaining a light-emitting device according to an embodiment of the present invention. 4 is a cross-sectional view for explaining a light-emitting diode according to another embodiment of the present invention. 5(a) and 5(b) to 7 are a plan view and a cross-sectional view for explaining a light-emitting diode according to another embodiment of the present invention.

As shown in FIG. 2, the light emitting device includes a light emitting diode 100 and a substrate 200. The light emitting diode 100 may be located on the substrate 200.

The light emitting diode 100 includes a light emitting structure 120, a first bump 161, a second bump 163, and a heat dissipation electrode 170. Further, the light emitting diode 100 may further include an insulating layer 150 and an insulating material portion 180. On the other hand, the substrate 200 may include a susceptor 210, a conductive pattern 230, and may further include an insulation pattern 220 at least a portion of the area between the susceptor 210 and the conductive pattern 230.

First, the light-emitting diode 100 will be described.

The light emitting structure 120 includes a first conductive type semiconductor layer, a second conductive type semiconductor layer, and an active layer between the first conductive type semiconductor layer and the second conductive type semiconductor layer, and includes a structure capable of emitting light. The structure of the light-emitting structure 120 is not particularly limited as long as it can electrically connect the first bump 161 and the second bump 163 in the lower direction. The specific structure of the light-emitting diode 100 and the light-emitting structure 120 will be described later with reference to FIGS. 4 to 7.

The first bump 161 and the second bump 163 may be located at a lower portion of the light emitting structure 120. The first bump 161 and the second bump 163 are insulated from each other and can be electrically connected with different polarities. For example, the first bump 161 may be electrically connected to the N-type semiconductor layer of the light emitting structure 120, and the second bump 163 may be electrically connected to the P-type semiconductor layer of the light emitting structure 120.

The first bump 161 may be disposed adjacent to a side of the lower surface of the light emitting structure 120. Correspondingly, the second bump 163 may be disposed adjacent to the other side of the lower surface of the light emitting structure 120. At this time, as shown in the drawing, a prescribed space may be provided in a region between the first bump 161 and the second bump 163. The predetermined heat dissipation electrode 170 may be disposed in the space. Therefore, the heat dissipation electrode 170 may be disposed between the first bump 161 and the second bump 163. However, the present invention is not limited to this and can be It is necessary to variously change the arrangement of the first bump 161 and the second bump 163 and the heat dissipation electrode 170.

On the other hand, the first bump 161 and the second bump 163 may contain a conductive substance such as metal, and particularly may include solder. The solder may be a solder known to those skilled in the art and may contain tin, copper, silver, antimony, indium (In), zinc, antimony, lead, and the like. For example, the solder may be a tin-silver-copper based solder.

In addition, the first bump 161 and the second bump 163 may be formed in a single layer or a plurality of layers, respectively. When the first bump 161 and the second bump 163 are formed in a single layer, the first bump 161 and the second bump 163 may be formed of solder, respectively. Unlike this, when the first bump 161 and the second bump 163 are formed in a plurality of layers, the solder layer may be disposed at the lowermost portion. At this time, the solder layer may be in contact with and bonded to the conductive pattern 230 of the substrate 200.

The heat dissipation electrode 170 may be located at a lower portion of the light emitting structure 120 and physically connected to the light emitting structure 120. The heat dissipation electrode 170 functions to dissipate heat generated by the light emitting structure 120 from the light emitting structure 120 to the outside.

The heat dissipation electrode 170 may include a material having relatively high thermal conductivity. In particular, the thermal conductivity of the heat dissipation electrode 170 may be higher than the thermal conductivity of the first bump 161 and the second bump 163. The heat dissipation electrode 170 may contain metal and, in addition, may include solder. The solder may be a solder known to those skilled in the art and may contain tin, copper, silver, antimony, indium, zinc, antimony, lead, and the like. For example, the solder may be tin-silver-copper based solder, but the invention is not limited thereto. In particular, the solder of the heat dissipation electrode 170 may be formed to have higher thermal conductivity than the first bump 161 and the second bump 163.

In addition, the heat dissipation electrode 170 may be formed in a single layer or a plurality of layers. When the heat dissipation electrode 170 is formed in a plurality of layers, the solder layer can be disposed at the lowermost portion. At this time, the solder layer may be in contact with and bonded to the susceptor 210 of the substrate 200.

The heat dissipation electrode 170 is physically connected to the light emitting structure 120, and the larger the area of the heat dissipation electrode 170, the higher the heat dissipation efficiency. Therefore, the area of the heat dissipation electrode 170 in contact with the light emitting structure 120 may be larger than the area in which the first bump 161 and/or the second bump 163 are in contact with the light emitting structure 120. In addition, the thermal conductivity of the heat dissipation electrode 170 can be greater than the thermal conductivity of the first bump 161 and the second bump 163, so that the heat dissipation efficiency of the light emitting device can be further improved. In addition, the heat dissipation electrode 170 may be located between the first bump 161 and the second bump 163 and further located on the lower side of the central portion of the light emitting structure 120. However, the present invention is not limited thereto, and the arrangement of the heat dissipation electrode 170, the first bump 161, and the second bump 163 can be variously changed.

Further, the light emitting diode 100 may further include an insulating layer 150, and the light emitting structure 120 and the heat dissipation electrode 170 may be insulated by the insulating layer 150. The insulating layer 150 may contain an anthracene insulating material such as SiO _x or SiN _x , and may further contain another insulating material excellent in thermal conductivity. In addition, it is also possible to include a Bragg reflector in which the dielectric layers having different refractive indices are alternately stacked.

As described above, the heat dissipation electrode 170 is insulated from the light emitting structure 120 by the insulating layer 150, and it is possible to prevent circuit failure such as short circuit due to the heat radiation electrode 170 during operation of the light emitting device as much as possible. At the same time, the heat dissipating electrode 170 and the light emitting structure 120 are physically connected via the insulating layer 150, so that the heat generated by the light emitting structure 120 can be effectively conducted to the heat dissipating electrode 170, thereby improving the heat dissipating efficiency of the light emitting diode 100.

As described above, according to the present invention, the first bump 161, the second bump 163, and the heat dissipation electrode 170 contain solder. Therefore, in the process of mounting the light-emitting diode 100 on the substrate 200, the substrate 200 can be connected only by the process of arranging the light-emitting diode 100 in a predetermined region of the substrate 200 and heating it to a temperature equal to or higher than the melting point of the solder. The light emitting diode 100 is combined.

Specifically, a method of manufacturing a light-emitting device according to another embodiment of the present invention will be described with reference to FIG. 3.

As shown in FIG. 3, the light-emitting diode 100 is disposed on the substrate 200 including the susceptor 210 and the conductive pattern 230. At this time, the light emitting diode 100 can be disposed at a position corresponding to the protruding portion of the susceptor 210. Just because the susceptor 210 includes a protrusion, the protrusion functions to mark the mounting area of the light-emitting diode 100. Therefore, in the process of mounting the light-emitting diode 100, the process of disposing the light-emitting diode 100 is simplified.

Then, when the temperature is heated to the melting point of the solder or more and then cooled, the solder contained in the first bump 161, the second bump 163, and the heat dissipation electrode 170 is melted and then cooled, and the light emitting diode 100 is bonded to the substrate 200. In particular, in the case where the insulating material portion 180 is formed, the first bump 161, the second bump 163, and the heat dissipation electrode 170 do not flow to the side surface or the shape thereof is deformed, and reliability can be improved.

As described above, according to the present invention, other processes required for bonding the light-emitting diode 100 and the substrate 200 can be omitted. For example, it is not necessary to add solder or an adhesive between the light-emitting diode 100 and the substrate 200 for bonding. Therefore, problems such as short circuit of the circuit which may occur in the soldering process can be avoided, and the process of mounting the light emitting diode 100 on the substrate 200 becomes very simple. In addition, it is possible to prevent defects that may occur in the bonding process such as soldering, and to improve the reliability of the manufactured light-emitting device.

Referring to FIG. 2 again, the LED assembly 100 may further include an insulating material portion 180 that surrounds the first bump 161, the second bump 163, and the side surface of the heat dissipation electrode 170.

The insulating material portion 180 has electrical insulation and covers the side surfaces of the first bump 161, the second bump 163, and the heat dissipation electrode 170, and is effectively insulated. at the same time, The insulating material portion 180 functions to support the first bump 161, the second bump 163, and the heat dissipation electrode 170. Therefore, in the process of attaching the light-emitting diode 100 to the substrate 200, it is possible to prevent the solder contained in the first bump 161, the second bump 163, and the heat dissipation electrode 170 from being melted and coming into contact with each other.

The lower surface of the insulating material portion 180 may be formed side by side at substantially the same height as the lower surfaces of the first bump 161, the second bump 163, and the heat dissipation electrode 170. Therefore, the light emitting diode 100 can be attached to the substrate 200 more stably.

The insulating material portion 180 may contain a resin. The resin may contain hydrazine or various high molecular substances. Further, the insulating material portion 180 may have a light reflecting property, and when the insulating material portion 180 contains a resin, the resin may be a reflective resin containing ruthenium. Alternatively, the resin may contain a light-reflecting property such as titanium dioxide particles and astigmatism particles. Just because the insulating material portion 180 is reflective, light emitted from the light emitting structure 120 is reflected to the upper portion, improving the light efficiency of the light emitting device.

In addition, the insulating material portion 180 may further cover the side surface of the light emitting structure 120. At this time, the light emitting angle of the light emitting diode 100 may change. That is, when the insulating material portion 180 also covers the side surface of the light emitting structure 120, part of the light emitted from the side surface of the light emitting diode 100 is reflected to the upper portion. Therefore, if the insulating material portion 180 is also formed on the side surface of the light emitting structure 120, the ratio of light incident on the upper portion of the light emitting diode 100 becomes high. As described above, by adjusting the arrangement area of the insulating material portion 180, the light-emitting angle of the light-emitting diode 100 can be adjusted.

The substrate 200 includes a susceptor 210, a conductive pattern 230, and further, an insulating pattern 220.

The susceptor 210 can function as a support of the substrate 200, and in particular, can contain a substance excellent in thermal conductivity. For example, the susceptor 210 can include thermal conductivity Excellent metal materials, including silver, copper, gold, aluminum, molybdenum, etc. In addition, the susceptor 210 may be formed in a single layer or a plurality of layers. Unlike the susceptor 210, the susceptor 210 may contain a ceramic material or a polymer material having excellent thermal conductivity.

In addition, the susceptor 210 may be in direct contact with the heat dissipation electrode 170. Further, the susceptor 210 may include a protrusion that is in contact with the heat dissipation electrode 170 of the light emitting diode 100. The upper surface of the protruding portion may be disposed at substantially the same height as the upper surface of the conductive pattern 230. Therefore, when the light-emitting diode 100 is mounted on the substrate 200, the susceptor 210 and the heat-dissipating electrode 170 can be stably contacted.

Just because the heat radiating electrode 170 is directly in contact with the susceptor 210 containing a substance having high thermal conductivity, heat generated when the light emitting diode 100 emits light can be efficiently conducted to the susceptor 210. Therefore, the heat dissipation efficiency of the light-emitting device can be improved.

According to the present invention, the light-emitting structure 120 and the heat-dissipating electrode 170 and the susceptor 210 of the substrate 200 are physically connected, so that heat generated during light-emitting can be efficiently radiated. In other words, it is possible to solve the problem of low thermal conductivity between the substrate pedestal and the light-emitting diode which have existed in the past.

The conductive pattern 230 may be located on the susceptor 210 and insulated from the susceptor 210. The conductive pattern 230 may be electrically connected to the first bump 161 and the second bump 163. Therefore, the conductive pattern 230 may include a first conductive pattern electrically connected to the first bump 161 and a second conductive pattern electrically connected to the second bump 163, and the first and second conductive patterns may be insulated from each other. As shown, the first bumps 161 and the second bumps 163 are located on the conductive pattern 230, and they can be electrically connected to each other.

When the susceptor 210 includes a conductive material such as metal, the insulating pattern 220 may be located between the susceptor 210 and the conductive pattern 230 to insulate the susceptor 210 and the conductive pattern 230. In addition, when the susceptor 210 includes a protrusion, the conductive pattern The 230 and the projections can be insulated from each other. Further, an insulating substance (not shown) may be interposed between the protruding portion of the susceptor 210 and the conductive pattern 230.

Unlike this, when the susceptor 210 contains a ceramic substance or a polymer substance and has electrical insulation, the insulation pattern 220 can be omitted.

However, the present invention is not limited thereto, and the conductive pattern 230 may be formed in plurality. The conductive pattern 230 can be variously changed in accordance with the number and shape of the bumps of the light-emitting diode 100. The conductive pattern 230 may function as a circuit or as a lead of the light-emitting device.

On the other hand, the conductive pattern 230 may be disposed at a position corresponding to the first bump 161 and the second bump 163, and the protruding portion of the susceptor 210 may be disposed at a position corresponding to the heat dissipation electrode 170. Further, the upper surface of the conductive pattern 230 and the upper surface of the protruding portion may be formed side by side at the same height. Therefore, the light emitting diode 100 can be stably attached to the upper surface of the substrate 200. The conductive pattern 230 may include a metal.

The substrate 200 according to the embodiment of the present invention has a configuration in which the insulating pattern 220 and the conductive pattern 230 are disposed on the susceptor 210. Therefore, the process of patterning the insulating layer between the susceptors can be omitted, and the manufacturing cost of the light-emitting device can be reduced. In addition, the susceptor 210 includes a protruding portion that can directly contact the heat dissipating electrode 170 of the illuminating diode 100, increasing the contact area between the pedestal 210 and the illuminating diode 100, and significantly improving the heat dissipation efficiency.

On the other hand, in the present embodiment, the case where one light-emitting diode 100 is mounted on the substrate 200 is exemplified, but the present invention is not limited thereto. The light-emitting device of the present invention may further include a structure in which a plurality of light-emitting diodes 100 are mounted on the substrate 200. The plurality of light emitting diodes 100 can be electrically connected by series, parallel, anti-parallel, and the like. connection. The electrical connection between the plurality of light emitting diodes 100 may be provided by the conductive pattern 230, at which time the conductive pattern 230 functions the same as the circuit.

As described above, the light-emitting device of the present invention may include a plurality of forms of light-emitting diodes. First, Fig. 4 is a cross-sectional view for explaining a light-emitting diode according to another embodiment of the present invention. In the embodiment of FIG. 4, the detailed description of the structure having the same reference numerals as those of the structure explained with reference to FIG. 2 will be omitted.

As shown in FIG. 4, the light emitting diode 100a according to another embodiment of the present invention may be a flip chip type light emitting diode. The light emitting diode 100a may include a light emitting structure 120, a first bump 161, a second bump 163, and a heat dissipation electrode 170. Further, the light emitting diode 100 may further include a first electrode sheet 141, a second electrode sheet 131, and an insulating layer 150. '.

The light emitting structure 120 may include a first conductive type semiconductor layer 121, a second conductive type semiconductor layer 125, and an active layer 123 between the first conductive type semiconductor layer 121 and the second conductive type semiconductor layer 125. The light emitting structure 120 may include a mesa including a second conductive type semiconductor layer 125 and an active layer 123, and a portion of the first conductive type semiconductor layer 121 may be exposed at a portion where the mesa is not formed.

The first conductive semiconductor layer 121, the active layer 123, and the second conductive semiconductor layer 125 may include a Group III-Group 5 compound semiconductor, and for example, may include a nitride-based semiconductor such as (aluminum, gallium, indium) nitrogen. The first conductive type semiconductor layer 121 may include an n-type impurity (for example, germanium), and the second conductive type semiconductor layer 125 may include a p-type impurity (for example, magnesium). In addition, it can be the opposite. The active layer 123 may include a multiple quantum well structure (MQW).

The first electrode sheet 141 is located at a region where the first conductive type semiconductor layer 121 is exposed, and may be located between the first bump 161 and the first conductive type semiconductor layer 121. Similarly, the second electrode sheet 131 is located on the second conductive type semiconductor layer 125, which can It is located between the second bump 163 and the second conductive type semiconductor layer 125. The first electrode sheet 141 and the second electrode sheet 131 may be in ohmic contact with the first conductive type semiconductor layer 121 and the second conductive type semiconductor layer 125, respectively.

In addition, the light emitting diode 100a may further include an insulating layer 150', and the insulating layer 150' may be disposed between the light emitting structure 120 and the heat radiating electrode 170. Further, the insulating layer 150' covers the lower surface of the light emitting structure 120 and the side faces of the first electrode sheet 141 and the second electrode sheet 131, and protects the light emitting structure 120 from the outside. The insulating layer 150' may comprise a substance similar to the insulating layer 150 shown in the embodiment of FIG.

On the other hand, FIG. 4 shows the light-emitting diode 100a from which the growth substrate is removed, and on the other hand, the light-emitting diode 100a may further include a growth substrate on the first conductive type semiconductor layer 121. In this case, the growth substrate is not limited as long as it can grow the light-emitting structure 120, and may be, for example, a sapphire substrate, a tantalum carbide substrate, a tantalum substrate, a gallium nitride substrate, or an aluminum nitride substrate.

As shown in FIG. 4, the lower portion of the light-emitting structure 120 of the general flip-chip type light-emitting diode 100a is formed with a first bump 161, a second bump 163, and a heat-dissipating electrode 170, without changing the conventional flip-chip light-emitting diode. The structure also provides a light-emitting diode that improves heat dissipation efficiency. Further, the light-emitting diode 100a shown in FIG. 4 can be disposed on the substrate 200 to provide a light-emitting device excellent in heat dissipation efficiency.

5(a) and 5(b) to 7 are a plan view and a cross-sectional view for explaining a light-emitting diode according to another embodiment of the present invention. Fig. 5(a) is a plan view showing the positions of the plurality of holes 120a and the connection holes 120b, and Fig. 5(b) is a plan view showing the lower surface of the light-emitting diode 100b. 6 and 7 are cross-sectional views showing the line A-A and the line B-B in a plan view of Figs. 5(a) and 5(b), respectively.

As shown in FIG. 5(a) and FIG. 5(b) to FIG. 7, the light emitting diode 100b includes: The light emitting structure 120 includes a first conductive semiconductor layer 121, an active layer 123 and a second conductive semiconductor layer 125; an electrode layer 130; a first metal layer 140; a first insulating layer 151; a first bump 161; The second bump 163 and the heat dissipation electrode 170. Further, the light emitting diode 100b may further include a second insulating layer 153 and an insulating material portion 180.

The light emitting structure 120 may include a first conductive type semiconductor layer 121, an active layer 123 on the first conductive type semiconductor layer 121, and a second conductive type semiconductor layer 125 on the active layer 123. In addition, the light emitting structure 120 may include a plurality of holes 120a penetrating through the second conductive type semiconductor layer 125 and the active layer 123 to expose a portion of the first conductive type semiconductor layer 121, and further, the light emitting structure 120 is further At least one connection hole 120b connecting the plurality of holes 120a may be included.

The first conductive semiconductor layer 121, the active layer 123, and the second conductive semiconductor layer 125 may include a Group III-Group 5 compound semiconductor, and for example, may include a nitride-based semiconductor such as (aluminum, gallium, indium) nitrogen. The first conductive type semiconductor layer 121 may include an n-type impurity (for example, germanium), and the second conductive type semiconductor layer 125 may include a p-type impurity (for example, magnesium). In addition, it can be the opposite. The active layer 123 may include a multiple quantum well structure (MQW).

The plurality of holes 120a may partially remove the active layer 123 and the second conductive type semiconductor layer 125, and partially expose the upper surface of the first conductive type semiconductor layer 121. The number and arrangement positions of the plurality of holes 120a are not limited. For example, as shown, a plurality of holes 120a may be disposed on the entire light emitting structure 120.

In addition, the plurality of holes 120a may be connected to each other by at least one connection hole 120b, which partially removes the active layer 123 and the second conductive type semiconductor layer 125 to partially expose the upper surface of the first conductive type semiconductor layer 121. . For example, as shown in FIG. 5(a), the plurality of holes 120a may be connected to each other by a plurality of connection holes 120b. In particular, all of the holes 120a can be connected.

As will be described later, the first metal layer 140 may form an ohmic contact with the first conductive type semiconductor layer 121 through the holes 120a. Therefore, a plurality of holes 120a are disposed on the entire light emitting structure 120, so that current can be distributed substantially uniformly over the entire light emitting structure 120. Further, the plurality of holes 120a are connected to each other by the connection holes 120b, and the current is not concentrated on the specific holes 120a, but is substantially uniformly dispersed over the entire light-emitting structure 120.

In addition, a rough surface R formed by increasing the roughness of the upper surface of the light-emitting structure 120 may be included. The rough surface R can be formed by dry etching and/or wet etching. For example, the upper surface of the light-emitting structure 120 is wet-etched using at least one of potassium hydroxide and sodium hydroxide to form a rough surface R, or photoelectrochemical (PEC) etching may be used. In addition, dry etching and wet etching may be combined to form a rough surface R. The rough surface R forming method as described above is merely an example, and the rough surface R may be formed on the surface of the light emitting structure 120 by various methods known to those skilled in the art. Forming a rough surface R on the surface of the light-emitting structure 120 can improve the light extraction efficiency of the light-emitting diode 100b.

In addition, the first metal layer 140 is in ohmic contact with the first conductive semiconductor layer 121 through the hole 120a, and the active layer 123 is removed from the region corresponding to the plurality of electrodes or the like connected to the first conductive semiconductor layer 121. The area of the hole 120a is the same. Therefore, the region where the first conductive type semiconductor layer 121 and the metal layer form an ohmic contact is minimized, and a light emitting diode having a larger ratio of the light emitting region area with respect to the horizontal area of the entire light emitting structure can be provided.

The electrode layer 130 is on the second conductive type semiconductor layer 125. The electrode layer 130 partially covers the lower surface of the second conductive type semiconductor layer 125 and may form an ohmic contact. In addition, the electrode layer 130 may be configured to cover the second conductive type semiconductor layer in an entire manner. The lower surface of 125 may be formed in one piece. That is, the electrode layer 130 may be formed to entirely cover other regions than the regions formed by the plurality of holes 120a and the connection holes 120b. Therefore, current is uniformly supplied to the entire light-emitting structure 120, and the current dispersion effect is improved.

However, the present invention is not limited thereto, and the electrode layer 130 may not be formed in a single body, and a plurality of unit electrode layers may be disposed on the lower surface of the second conductive type semiconductor layer 125.

The electrode layer 130 may include a reflective layer and a cover layer covering the reflective layer.

As described above, the electrode layer 130 forms an ohmic contact with the second conductive type semiconductor layer 125, and can exert a light reflecting effect. Therefore, the reflective layer may include a metal having a high reflectance and capable of forming an ohmic contact with the second conductive type semiconductor layer 125. For example, the reflective layer may include at least one of nickel, platinum, palladium, rhodium, tungsten, titanium, aluminum, silver, and gold. In addition, the reflective layer may include a single layer or multiple layers.

The cover layer can prevent mutual diffusion between the reflective layer and different substances, and can prevent other external substances from diffusing to the reflective layer to cause damage to the reflective layer. Therefore, the cover layer may be formed to cover the bottom and sides of the reflective layer. The cover layer can be electrically connected to the second conductive type semiconductor layer 125 together with the reflective layer, which can function as an electrode together with the reflective layer. The cover layer may comprise at least one of gold, nickel, titanium, chromium, and may also comprise a single layer or multiple layers.

Unlike this, the electrode layer 130 may contain other conductive materials and may include a transparent electrode. The transparent electrode may include at least one of indium tin oxide (ITO), zinc oxide (ZnO), zinc aluminum oxide (AZO), and indium zinc oxide (IZO).

On the other hand, the light emitting diode 100b may further include a first insulating layer 151. The first insulating layer 151 may partially cover the bottom of the light emitting structure 120 and the electrode layer 131. In addition, the first insulating layer 151 may partially fill the connection hole 120b sandwiched between the first conductive type semiconductor layer 121 and the first metal layer 140 exposed to the connection hole 120b, which may be other than the plurality of holes 120a The region is sandwiched between the first metal layer 140 and the electrode layer 130. Further, the first insulating layer 151 may cover the side faces of the plurality of holes 120a while exposing the upper surface of the holes 120a, thereby partially exposing the first conductive semiconductor layer 121. Further, the first insulating layer 151 may cover the side surface of the light emitting structure 120.

The first insulating layer 151 may include a first opening portion 151a located at a position corresponding to a position where the plurality of holes 120a are located, and a second opening portion 151b partially exposing the electrode layer 130. The first conductive semiconductor layer 121 may be partially exposed by the first opening 151a and the hole 120a, and the electrode layer 130 may be partially exposed by the second opening 151b.

The first insulating layer 151 may contain an insulating substance, and for example, may include SiO ₂ or SiN _x . Further, the first insulating layer 151 may include a plurality of layers, and may also include a distributed Bragg reflector in which substances having different refractive indices are alternately stacked.

The first metal layer 140 may be located under the light emitting structure 120, and the first metal layer may fill the plurality of holes 120a and/or the first opening portion 151a, which form an ohmic contact with the first conductive type semiconductor layer 121. The first metal layer 140 may be formed to entirely cover portions other than a partial region of the lower surface of the first insulating layer 151. In addition, unlike the drawing, the first metal layer may be formed to cover the side surface of the light emitting structure 120. When the first metal layer 140 is also formed on the side surface of the light-emitting structure 120, the light emitted from the active layer 123 to the side surface can be reflected upward, and the ratio of the light reflected from the upper portion of the light-emitting diode 100b can be increased. On the other hand, the first metal layer 140 can The electrode layer 130 is insulated from the region not corresponding to the second opening portion 151b of the first insulating layer 151.

The first metal layer 140 is formed to cover the lower surface of the light emitting structure 120 in all but a part of the region, and the current dispersion effect can be further improved. Further, the portion not covered by the electrode layer 130 is covered by the first metal layer 140, and light reflection is performed more efficiently, thereby improving the luminous efficiency of the light-emitting diode 100b.

The first metal layer 140 forms an ohmic contact with the first conductive semiconductor layer 121 and functions as a light reflection. Therefore, the first metal layer 140 may include a highly reflective metal layer such as an aluminum layer, and the highly reflective metal layer may be formed on an adhesion layer of titanium, chromium, or nickel.

The light emitting diode 100b may further include a second insulating layer 153, and the second insulating layer 153 may cover the first metal layer 140. The second insulating layer 153 may include a third opening portion 153a that partially exposes the first metal layer 140, and a fourth opening portion 153b that partially exposes the electrode layer 130. At this time, the fourth opening portion 153b may be formed at a position corresponding to the second opening portion 151b.

One or more of the third opening portion 153a and the fourth opening portion 153b may be formed. Further, when the third opening portion 153a is located adjacent to a corner of the light emitting diode 100b, the fourth opening portion 153b may be located at the other adjacent corner.

The second insulating layer 153 may contain an insulating substance, and for example, may include cerium oxide (SiO ₂ ) or SiN _x . Further, the second insulating layer 153 may include a plurality of layers, and may also include a distributed Bragg reflector in which substances having different refractive indices are alternately stacked.

The first bump 161 may be located under the second insulating layer 153 and electrically connected to the first metal layer 140 through the third opening portion 153a. The second bump 163 may be located under the second insulating layer 153 and electrically connected to the electrode layer 130 by the fourth opening portion 153b. Pick up. Therefore, the first bump 161 and the second bump 163 are electrically connected to the first conductive semiconductor layer 121 and the second conductive semiconductor layer 125, respectively. Therefore, the first bump 161 and the second bump 163 can function as electrodes that supply power from the outside to the light emitting diode.

The heat dissipation electrode 170 may be located under the second insulation layer 153 and may be located at a lower portion of the light emitting structure 120. The heat dissipating electrode 170 is physically connected to the light emitting structure 120 to function to dissipate heat generated by the light emitting structure 120 from the light emitting structure 120 to the outside. In addition, the heat dissipation electrode 170 may be located between the first bump 161 and the second bump 163 and further located on the lower side of the central portion of the light emitting structure 120. However, the present invention is not limited thereto, and the arrangement of the heat dissipation electrode 170, the first bump 161, and the second bump 163 can be variously changed.

In addition, as illustrated in the embodiment of FIG. 2, the first bump 161 and the second bump 163 and the heat dissipation electrode 170 may include solder.

According to the present invention, it is possible to provide a light-emitting device including the light-emitting diode 100b explained in the embodiment of FIGS. 5(a) and 5(b) to 7. The light-emitting diode 100b of the present embodiment has a high current dispersion effect and can be turned on with a high current, and the heat dissipation efficiency is high even when a high current is turned on. Therefore, the light emitting diode structure of the present embodiment is very suitable for use in a high power light emitting device.

The various embodiments of the present invention have been described above, but the present invention is not limited to the various embodiments described above, and various modifications and changes can be made without departing from the spirit and scope of the invention.

100‧‧‧Lighting diode

120‧‧‧Lighted structure

150‧‧‧Insulation

161‧‧‧First bump

163‧‧‧second bump

170‧‧‧heating electrode

180‧‧‧Inserts Division

200‧‧‧Substrate

210‧‧‧Base

220‧‧‧Insulation pattern

230‧‧‧Electrical pattern

Claims (23)

A light-emitting device comprising: a light-emitting diode; and a substrate, the substrate comprising a base and a conductive pattern on the base, and the substrate is mounted to the light-emitting diode, the light-emitting diode The polar body includes: a light emitting structure including a first conductive type semiconductor layer, an active layer under the first conductive type semiconductor layer, and a second conductive type semiconductor layer located under the active layer a region partially removing the active layer and the second conductive semiconductor layer to partially expose a lower surface of the first conductive semiconductor layer; an electrode layer located under the second conductive semiconductor layer Forming an ohmic contact; a first metal layer forming an ohmic contact with the first conductive type semiconductor layer through the exposed region of the first conductive type semiconductor layer; a first insulating layer partially covering the a first metal layer and the electrode layer; a first bump and a second bump located in a lower portion of the light emitting structure and in contact with the conductive pattern, the first bump and the second bump The blocks are electrically connected to the first metal layer and the electrode layer, respectively, and the first bump and the second bump are in direct contact with a portion of the first metal layer and a portion of the electrode layer, respectively And a heat dissipating electrode located at a lower portion of the light emitting structure and in contact with the pedestal; The region in which the first conductive semiconductor layer is partially exposed includes a plurality of holes in which the first conductive semiconductor layer is exposed and at least one connection hole connecting the holes, and the first bump and the The second bump and the heat dissipating electrode are spaced apart from each other, and the heat conducting electrode has higher thermal conductivity than the first bump and the second bump. The illuminating device of claim 1, wherein the illuminating diode further comprises an insulating material portion, the insulating material portion covering the first bump, the second bump, and the heat dissipation The side of the electrode. The illuminating device of claim 2, wherein: a lower surface of the insulating material portion, a lower surface of the first bump, a lower surface of the second bump, and a lower surface of the heat dissipating electrode The surfaces are formed side by side at the same height. The light-emitting device according to claim 3, wherein the base includes a protrusion, and an upper surface of the protrusion and an upper surface of the conductive pattern are formed side by side at the same height. The light-emitting device of claim 2, wherein the first bump, the second bump, and the heat dissipation electrode comprise solder. The illuminating device of claim 1, wherein the heat dissipating electrode is located between the first bump and the second bump. The illuminating device of claim 6, wherein the conductive pattern comprises a first conductive pattern in contact with the first bump and a second conductive pattern in contact with the second bump The pedestal includes a protrusion between the first conductive pattern and the second conductive pattern. The illuminating device of claim 1, wherein: The photodiode further includes an insulating layer between the light emitting structure and the heat dissipating electrode. The light-emitting device of claim 1, wherein the first bump and the second bump are directly bonded to the conductive pattern. The light-emitting device of claim 1, further comprising an insulation pattern between the susceptor and the conductive pattern, the pedestal and the conductive pattern comprising a metal. The light-emitting device of claim 1, wherein the electrode layer is formed in a single body. A light emitting diode comprising: a light emitting structure comprising a first conductive semiconductor layer, an active layer under the first conductive semiconductor layer, and a second conductive semiconductor layer under the active layer; a region in which the active layer and the second conductive semiconductor layer are partially removed to partially expose a lower surface of the first conductive semiconductor layer; and an electrode layer located under the second conductive semiconductor layer Forming an ohmic contact; a first metal layer forming an ohmic contact with the first conductive type semiconductor layer through the exposed region of the first conductive type semiconductor layer; a first insulating layer partially covering the first a metal layer and the electrode layer; a first bump and a second bump located at a lower portion of the light emitting structure and electrically connected to the first metal layer and the electrode layer, respectively, wherein the first The bump and the second bump are in direct contact with a portion of the first metal layer and a portion of the electrode layer, respectively; a heat dissipating electrode located at a lower portion of the light emitting structure; wherein the region partially exposed by the first conductive semiconductor layer includes a plurality of holes exposed by the first conductive semiconductor layer and a hole connecting the holes At least one connection hole, wherein the first bump, the second bump and the heat dissipation electrode are spaced apart from each other, and the heat dissipation electrode has higher thermal conductivity than the first bump and the second bump Thermal conductivity. The light-emitting diode according to claim 12, wherein the light-emitting diode further includes an insulating material portion, the insulating material portion covering the first bump, the second bump, and the The side of the heat sink electrode is described. The light-emitting diode according to claim 13, wherein the first bump, the second bump, and the heat dissipation electrode comprise solder. The light emitting diode according to claim 12, wherein the heat dissipating electrode is located between the first bump and the second bump. The light-emitting diode according to claim 12, further comprising: an insulating layer between the light-emitting structure and the heat-dissipating electrode. A method of manufacturing a light-emitting device, wherein a light-emitting diode is mounted on a substrate, the substrate includes a base and a conductive pattern on the base, wherein the light-emitting diode comprises: a light-emitting structure, The method includes a first conductive semiconductor layer, an active layer under the first conductive semiconductor layer, and a second conductive semiconductor layer under the active layer; partially removing the active layer and the second conductive a region in which the lower surface of the first conductive semiconductor layer is partially exposed; An electrode layer located under the second conductive type semiconductor layer and forming an ohmic contact; a first metal layer passing through the region exposed by the first conductive type semiconductor layer and the first conductive type semiconductor layer Forming an ohmic contact; a first insulating layer partially covering the first metal layer and the electrode layer; a first bump and a second bump located at a lower portion of the light emitting structure and having the conductivity In the pattern contact, the first bump and the second bump are electrically connected to the first metal layer and the electrode layer, respectively, wherein the first bump and the second bump respectively a portion of the first metal layer and a portion of the electrode layer are in direct contact; and a heat dissipating electrode located at a lower portion of the light emitting structure and in contact with the pedestal; wherein the first conductive semiconductor layer is partially exposed The region includes a plurality of holes exposing the first conductive semiconductor layer and at least one connection hole connecting the holes, and the first bump, the second bump, and the heat dissipation electrode are separated from each other Open, the heat sink The thermal conductivity is higher than the first bump and the second bump thermal conductivity, and wherein the first bump, the second bump electrode comprises solder, and the heat sink. The method of manufacturing a light-emitting device according to claim 17, wherein the light-emitting diode further includes an insulating material portion, the insulating material portion covering the first bump, the second bump, and the The side of the heat sink electrode is described. The method of manufacturing a light-emitting device according to claim 18, wherein the mounting the light-emitting diode on the substrate comprises: arranging the light-emitting diode in a predetermined region of the substrate, provided that Narrative a bump, the second bump, and the heat dissipation electrode are in contact with the substrate; and the first bump, the second bump, and the heat dissipation electrode are heated to a temperature above a melting point of the solder; And cooling the solder. The method of manufacturing the illuminating device of claim 17, wherein the pedestal includes a protrusion, the first bump and the second bump are disposed on the conductive pattern, and the heat dissipation An electrode is disposed on the protrusion. The method of manufacturing a light-emitting device according to claim 20, wherein the upper surface of the protruding portion and the upper surface of the conductive pattern are formed side by side at the same height. The method of manufacturing a light-emitting device according to claim 17, wherein the substrate further comprises an insulation pattern between the conductive pattern and the susceptor, the conductive pattern and the pedestal comprise metal. The method of manufacturing a light-emitting device according to claim 17, wherein the light-emitting diode further includes an insulating layer between the light-emitting structure and the heat-dissipating electrode.