CN110260182B

CN110260182B - Light emitting device

Info

Publication number: CN110260182B
Application number: CN201910547650.0A
Authority: CN
Inventors: 姚久琳; 甘硕杰; 林钧尉; 廖本瑜
Original assignee: Epistar Corp
Current assignee: Epistar Corp
Priority date: 2015-07-23
Filing date: 2015-07-23
Publication date: 2022-12-02
Anticipated expiration: 2035-07-23
Also published as: CN106369367A; CN110260182A; CN110260183A

Abstract

The invention discloses a light-emitting device, which comprises a carrier plate and a light-emitting unit, wherein the carrier plate is provided with a first surface, a second surface opposite to the first surface, and the light-emitting unit is arranged on the first surface and can emit light to face but not pass through the first surface. The light emitting device can obtain a first brightness above the first surface and a second brightness below the second surface, and the ratio of the first brightness to the second brightness is 2-9.

Description

Light emitting device

The application is a divisional application of Chinese patent application (application number: 201510438508.4, application date: 2015, 07, 23 and the name of the invention: a light-emitting device).

Technical Field

The present invention relates to a light emitting device, and more particularly, to a light emitting device having an optical structure.

Background

Light-Emitting diodes (LEDs) used in solid-state lighting devices have characteristics of low power consumption, long lifetime, small size, fast response speed, and stable optical output, and thus, they slowly replace conventional lighting products and are applied to general household lighting.

In recent years, filaments made of light emitting diodes have been used in light emitting diode bulbs. However, the cost and efficiency of the led filament still need to be improved. Furthermore, it is still a development goal to make the led filament emit an omnidirectional light field and to deal with the heat dissipation problem.

Disclosure of Invention

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described below.

A light-emitting device comprises a carrier plate and a light-emitting unit, wherein the carrier plate is provided with a first surface and a second surface opposite to the first surface, and the light-emitting unit is arranged on the first surface and can emit light to face but not penetrate through the first surface. The light emitting device can obtain a first brightness above the first surface and a second brightness below the second surface, and the ratio of the first brightness to the second brightness is 2-9.

Drawings

FIG. 1A is a schematic perspective view of a light emitting device according to an embodiment of the present invention;

FIG. 1B is a schematic top view of the carrier board in FIG. 1A;

fig. 1C is a schematic bottom view of the carrier plate in fig. 1A;

FIG. 1D is a schematic cross-sectional view of FIG. 1A taken along line BI-I of FIG. 1;

FIG. 1E is a schematic cross-sectional view of FIG. 1A;

FIG. 1F is an enlarged view of FIG. 1E;

FIGS. 2A to 2D are schematic diagrams illustrating different traveling paths of light emitted by the light emitting unit in the optical structure, respectively;

FIG. 2E is a light distribution graph of a light emitting device according to an embodiment of the invention;

FIG. 3A is a schematic cross-sectional view of a light-emitting unit according to an embodiment of the present invention;

FIG. 3B is a schematic cross-sectional view of a light-emitting unit according to another embodiment of the present invention;

FIG. 3C is a top view of FIG. 3B;

FIG. 3D is a schematic cross-sectional view of a light-emitting unit according to another embodiment of the present invention;

FIG. 4 is a perspective view of a lamp according to an embodiment of the present invention;

FIG. 5A is a flow chart illustrating a process of fabricating a light emitting device according to an embodiment of the present invention;

fig. 5B to 5E are schematic perspective views illustrating a manufacturing process of a light emitting device according to an embodiment of the invention.

Description of the symbols

100. Light emitting device

10. Optical structure

101. Top surface

102. Side surface

103. Side bottom surface

1031. The first part

1032. The second part

104. Bottom surface

11. Support plate

111. Upper surface of

112. Lower surface

12. 12A, 12B, 12D light emitting unit

120A first connection pad

120B second connecting pad

121. Light-emitting body

1211. Electrode for electrochemical cell

122. First transparent body

123. Phosphor layer

124. Second transparent body

125. 125' third transparency

1251. The first part

1251S side surface

1252. The second part

1253. Plane surface

1254. Inclined plane

126. Insulating layer

127. Extension electrode

129. Reflection structure

13. Circuit structure

131. A first electrode pad

132. Second electrode pad

133. Conductive traces 1331, 1331A, 1332B

134. Third electrode pad

135. Fourth electrode pad

151. The first through hole

152. A second through hole

21. Support frame

211. Frame structure

30. Light bulb

301. Lamp shell

302. Circuit board

303. Support column

304. Heat sink

305. Electrical connector

307. Electrode piece

308. 309 metal wire

Detailed Description

The following embodiments will explain the concept of the present invention along with the accompanying drawings, in which like reference numerals are used to refer to like or identical parts, and in which the shapes or thicknesses of elements may be enlarged or reduced. It is to be noted that elements not shown or described in the figures may be of a type known to those skilled in the art.

Fig. 1A is a schematic perspective view illustrating a light emitting device 100 according to an embodiment of the invention. Fig. 1B only shows a schematic top view of the carrier 11 in fig. 1A. Fig. 1C is a schematic bottom view of the carrier 11 in fig. 1A. FIG. 1D is a schematic cross-sectional view of FIG. 1A taken along line BI-I of FIG. 1. FIG. 1E shows a schematic cross-sectional view of FIG. 1A in the YZ direction. Referring to fig. 1A to 1E, the light emitting device 100 includes an optical structure 10, a carrier 11, and a plurality of light emitting units 12. The carrier 11 has an upper surface 111 and a lower surface 112. A circuit structure 13 is formed on the upper surface 111 and has a first electrode pad 131, a second electrode pad 132 and a conductive trace 133. The light emitting cells 12 are disposed on the conductive traces 133 of the upper surface 111 and are connected to each other in series through the conductive traces 133. In other embodiments, the light emitting cells 12 may be connected in parallel, in series, or in a bridge configuration by other types of conductive traces 133. In this embodiment, the carrier 11 is not penetrated (opaque) by the light emitted from the light emitting unit 12, so that even if the light emitted from the light emitting unit 12 is directed to the upper surface 111, it does not pass through the upper surface 111. The carrier 11 may be a circuit board. The substrate material (core layer) of the circuit board comprises a metal, a thermoplastic material, a thermosetting material, or a ceramic material. The metal comprises an alloy, laminate, or monolayer of aluminum, copper, gold, silver, or the like. The thermoset material comprises a phenolic resin (phosphonic), an Epoxy resin (Epoxy), a bismaleimide triazine resin (BismaleimideTriazine), or a combination thereof. The thermoplastic material includes Polyimide resin (Polyimide resin), polytetrafluoroethylene (polytetrafluoroethylene), and the like. The ceramic material includes alumina, aluminum nitride, silicon aluminum carbide, and the like.

As shown in fig. 1A, 1B and 1C, a reflective layer 14 is formed on the upper surface 111 and the circuit structure 13, and only the

conductive traces

1331 and 1332 and the

electrode pads

131 and 132 to be electrically connected to the light emitting unit 12 are exposed. The conductive line 1331 and the conductive line 1332 are physically separated from each other. In this embodiment, the conductive traces 1332A and the electrode pads 131 are physically separated from each other and the conductive traces 1331B and the electrode pads 132 are physically separated from each other. Each light emitting unit 12 includes a first connection pad 120A and a second connection pad 120B physically and electrically connected to the exposed

conductive traces

1331 and 1332, respectively. In the present embodiment, the exposed

conductive traces

1331, 1332 are rectangular and have long sides parallel to the long sides of the carrier 11. In another embodiment, the long sides of the exposed

conductive traces

1331, 1332 are parallel to the short sides of the carrier 11, or form an angle of 0-90 ° with the long sides. Alternatively, the exposed

conductive traces

1331, 1332 may be circular, elliptical, or polygonal. In addition, the reflective layer 14 can help to reflect the light emitted from the light-emitting unit 12 toward the carrier 11 to increase the overall light-emitting efficiency of the light-emitting device 100.

As shown in fig. 1C and 1D, the light emitting unit 12 is not disposed on the lower surface 112. The circuit structure 13 further includes a third electrode pad 134 and a fourth electrode pad 135 formed on the lower surface 112 of the carrier 11. The third electrode pad 134 and the fourth electrode pad 135 correspond to the first electrode pad 131 and the second electrode pad 132, respectively. A first through hole 151 penetrates the carrier 11 and has a conductive material formed therein completely or partially to electrically connect the first electrode pad 131 and the third electrode pad 134. A second through hole 152 penetrates the carrier 11 and has a conductive material formed therein completely or partially to electrically connect the second electrode pad 132 and the fourth electrode pad 135. In one embodiment, an external power supply (power supply) is connected to the first electrode pad 131 and the second electrode pad 132, respectively, to make the light emitting units 12 emit light. The third electrode pad 134 and the fourth electrode pad 135 may not be directly physically connected to an external power source. When the

electrode pads

131, 132 are electrically connected to an external power source by a spot welding, the

electrode pads

134, 135 are disposed to help the light emitting device 100 to be firmly clamped and provide a conductive path during the manufacturing process, since a metal clamp is required to clamp the carrier 11. In one embodiment, when the

electrode pads

131 and 132 are electrically connected to an external power source by using bonding wires, the third electrode pad 134 and the fourth electrode pad 135 may not be formed.

As shown in fig. 1A and 1E, the optical structure 10 covers the upper surface 111 and the lower surface 112 of the carrier 11 and the sidewalls 113 on both sides of the long side of the carrier 11, but exposes the

electrode pads

131, 132, 134, and 135. The optical structure 10 has a rectangular-like cross-section. Fig. 1F is an enlarged view of fig. 1E. The optical structure 10 has an arcuate top surface 101; two substantially linear side surfaces 102 parallel to each other; two side bottom surfaces 103; and a substantially planar bottom surface 104 connecting the two side bottom surfaces 103. Top surface 101 is located above upper surface 111 of carrier 11 and bottom surface 104 is located below lower surface 112 of carrier 11. The side surface 102 extends from the top surface 101 in the Z-direction towards the lower surface 112 of the carrier plate 11. Each side bottom surface 103 includes a first portion 1031 extending from the side surface 102 to the bottom surface 104 at an oblique angle; and a second portion 1302. The second portions 1302 on the left and right sides of the figure are connected to the first portions 1031, respectively, and extend toward the bottom surface 104 in an arc shape. The lower surface 112 of the carrier 11 is separated from the bottom surface 104 of the optical structure 10 by a first distance D1 between 0.3mm and 0.7 mm; the upper surface 111 of the carrier 11 is spaced apart from the top surface 101 of the optical structure 10 by a second distance D2 between 0.8mm and 0.13 mm. The second distance D2 is greater than the first distance D1. The arc of the top surface 101 has a radius of curvature of 0.4mm to 0.7mm, and has an arc angle θ 1 (a central angle corresponding to the arc) of 40 ° to 60 ° or an arc of 2 π/9 π/3. The second portion of the side bottom surface 103 has an arc with a radius of curvature of 0.2-0.4 mm, and has an arc angle θ 2 (the central angle corresponding to the arc) of 5-20 ° or an arc of π/36- π/9. A diffusing powder (e.g., titanium dioxide, zirconium oxide, zinc oxide, or aluminum oxide) may be optionally filled in the optical structure 10 to help diffuse and scatter the light emitted from the light-emitting unit 12. The weight percent concentration (w/w) of the diffusion powder in the optical structure 10 is between 0.1 and 0.5 percent and has a particle size of between 10nm and 100nm or between 10 and 50 mu m. In one embodiment, the weight percentage concentration of the dispersion powder in the colloid can be measured by thermogravimetric analyzer (TGA). Briefly, during the heating process, the colloid is removed (evaporated or thermally cracked) due to the gradual temperature rise and after reaching a specific temperature, and the weight change of the residual diffusion powder can be known, so that the respective weights of the colloid and the diffusion powder can be obtained and the weight percentage concentration of the diffusion powder in the colloid can be obtained. Or, the total weight of the colloid and the diffusion powder can be measured, the colloid is removed by using the solvent, and finally the weight of the diffusion powder is measured, so that the weight percentage concentration of the diffusion powder in the colloid is obtained. In fig. 1A, the light emitting unit 12 is visible. However, when the optical structure 10 is filled with the diffusion powder and reaches a certain concentration, the optical structure 10 is white and the light emitting unit 12 inside cannot be seen.

The optical structure 10 is transparent to sunlight or light emitted by the light emitting unit 12. The optical structure 10 includes Silicone (Silicone), epoxy (Epoxy), polyimide (PI), benzocyclobutene (BCB), perfluorocyclobutane (PFCB), SU8, acrylic (Acrylic Resin), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), polyetherimide (Polyetherimide), fluorocarbon Polymer (Fluorocarbon Polymer), aluminum oxide (Al) ₂ O ₃ ) SINR, or spin-on glass (SOG).

Fig. 2A is a schematic diagram illustrating a traveling path of light emitted by the light emitting unit 12 in the optical structure 10. It should be noted that the path in the drawing is only one of many possible paths, not the only path, and the following description. For example: the light L from the light emitting unit 12 is emitted to the arc-shaped top surface 101, and the light L generates a first refracted light L11 and a first reflected light L12 on the top surface 101. When the first reflected light L12 is emitted to the side surface 102, a second refracted light L21 and a second reflected light L22 are generated on the side surface 102. The second reflected light L22 is emitted to the bottom surface 104, and a third refracted light L31 and a third reflected light L32 are generated on the bottom surface 104. Alternatively, as shown in fig. 2B, for example: the light M from the light emitting unit 12 is emitted to the arc-shaped top surface 101, and the light M generates a first refracted light M11 and a first reflected light M12 on the top surface 101. The first reflected light M12 is emitted to the first portion 1031 of the side bottom surface 103, and a second refracted light M21 and a second reflected light M22 are generated in the first portion 1031. The second reflected light M22 is incident on the bottom surface 104, and a third refracted light M31 and a third reflected light M32 are generated on the bottom surface 104. Fig. 2C and 2D are schematic diagrams illustrating other possible paths of light rays in the optical structure 10. The shape of the optical structure 10 of the present invention is designed to increase the probability of light being emitted from the direction of the lower surface 112 of the carrier 10 and the probability of light being emitted from the bottom surface 104. The light emitting device 100 can obtain a first brightness above (a first side) the upper surface 111 and a second brightness below (a second side) the lower surface 112, and a ratio of the first brightness to the second brightness is between 2 and 9. The definition of the first brightness and the second brightness can refer to the following description. It should be noted that the path in the drawing is only one of many possible paths, and is not a unique path. In addition, in the above description, the light is refracted and reflected on the surface at the same time. However, light may also be merely refracted or reflected at the surface, depending on the refractive index difference at the material interface, the angle of incidence, the wavelength of the light, and so on.

FIG. 2E shows a light distribution diagram of the light emitting device 100 under the operation of current 10mA and in a thermal steady state. In detail, when the light emitting device 100 emits light, the light emitting luminance of an imaginary circle (e.g., the P1 circle in fig. 1A) can be measured by using a light distribution curve instrument. Furthermore, a light distribution curve chart can be obtained by plotting the brightness and the angle. In measurement, the geometric center of the light-emitting device 100 is substantially located at the center of the circle P1. In the present embodiment, the weight percentage concentration of the diffusion powder in the optical structure 10 is 0.3%. As shown, the maximum luminance of the light emitting device 100 is about 4.53 candela cd, and the luminance from 0 degree to 180 degree is substantially lambertian distribution (lambertian distribution). Specifically, the luminance at-90 degrees is the smallest and about 0.5 candela (cd), the luminance is about the same from-90 degrees to-80 degrees, and the luminance is gradually increased from-80 degrees to 90 degrees. The curve of-90-0-90 degrees is approximately similar to the curve of 90-180-90 degrees, and the distribution of light intensity at-90-0-90 degrees and the distribution of light intensity at 90-180-90 degrees are symmetrical with respect to the linear axis of 90-90 degrees. In addition, the total brightness of 0 to 90 to 180 degrees in the light distribution graph is defined as a first brightness, the total brightness of 0 to-90 to-180 degrees is defined as a second brightness, and the ratio of the first brightness to the second brightness is about 4. The light emission angle of the light emitting device 100 is about 160 degrees as calculated from the light distribution graph.

The light-emitting angle is defined as the angle range included when the brightness is 50% of the maximum brightness. For example: firstly, converting the light distribution curve graph (polar coordinate) measured on the P1 circle in FIG. 2E into a rectangular coordinate graph to obtain a brightness curve graph; wherein the X-axis is brightness and the Y-axis is angle (not shown). Then, a straight line was drawn parallel to the X-axis at about 2.265 candela (50% of maximum brightness) and intersects the graph of brightness at two points; the range of angles between the two points is calculated, i.e. defined as the light emission angle.

Fig. 3A is a schematic cross-sectional view of a light emitting unit 12A according to an embodiment of the invention. The light emitting unit 12A includes a light emitting body 121, a first transparent body 122, a phosphor layer 123, a second transparent body 124, and a third transparent body 125. The light emitting body 121 includes a substrate, a first type semiconductor layer, an active layer, a second type semiconductor layer (not shown), and two electrodes 1211. When the light-emitting body 121 is a heterostructure, the first type semiconductor layer and the second type semiconductor layer are, for example, a cladding layer (cladding layer) and/or a confining layer (confining layer), and can provide electrons and holes respectively and have an energy gap larger than that of the active layer, thereby increasing the probability of the electrons and holes combining in the active layer to emit light. The first-type semiconductor layer, the active layer, and the second-type semiconductor layer may comprise a III-V semiconductor material, such as Al _x In _y Ga _(1-x-y) N or Al _x In _y Ga _(1-x-y) P, wherein 0 ≦ x, y ≦ 1; (x + y) ≦ 1. Depending on the material of the active layer, the light-emitting body 121 may emit red light with a peak wavelength (peak wavelength) or dominant wavelength (dominant wavelength) between 610nm and 650nm, green light with a peak wavelength or dominant wavelength between 530nm and 570nm, or green light with a peak wavelength or dominant wavelength between 450nm and 490nmOf blue light. Phosphor structure 123 comprises a plurality of phosphor particles. The phosphor particles have a particle size (diameter) of about 5um to 100um and may comprise one or more types of phosphor materials. The phosphor material includes, but is not limited to, yellow-green phosphor and red phosphor. The yellow-green phosphor is composed of, for example, aluminum oxide (YAG or TAG), silicate, vanadate, alkaline earth metal selenide, or metal nitride. Composition of red phosphor such as fluoride (K) ₂ TiF ₆ :Mn ⁴⁺ 、K ₂ SiF ₆ :Mn ⁴⁺ ) Silicates, vanadates, alkaline earth metal sulfides, metal oxynitrides, or mixtures of the tungsten molybdate family. The phosphor structure 123 may absorb the first light emitted from the light emitting body 121 and convert the first light into a second light having a different spectrum from the first light. The first light and the second light are mixed to generate a mixed light, such as white light. In this embodiment, the light generated by the light emitting unit 12 in the thermal steady state has a white color temperature of 2200K to 6500K (e.g., 2200K, 2400K, 2700K, 3000K, 5700K, 6500K), a color point value (CIE x, y) falling within a range of seven MacAdam ellipses (MacAdam ellipsoses), and a Color Rendering Index (CRI) greater than 80 or greater than 90. In another embodiment, the first light and the second light are mixed to generate purple light, yellow light or other colored light other than white light.

The light emitting unit 12 further includes an insulating layer 126 formed below the first transparent body 122, the phosphor layer 123 and the second transparent body 124 and not covering the two electrodes 1211 of the light emitting body 121; and two extension electrodes 127 formed on the two electrodes 1211 and electrically connected to the two electrodes 1211, respectively. The two extension electrodes 127 are respectively used as the first connection pad 120A and the second connection pad 102B (as shown in fig. 1D). The insulating layer 126 is a mixture comprising a matrix and a high reflectivity material. The matrix may be either a silica gel matrix or an epoxy matrix. The high-reflectivity substance may comprise titanium dioxide, silicon dioxide, or aluminum oxide. In addition, the insulating layer 126 may have a function of reflecting light or diffusing light. The extension electrode 127 includes metals such as: copper, titanium, gold, nickel, silver, alloys thereof, or laminates thereof. The first transparent body 122, the second transparent body 124 and the third transparent body 125 are transparent to sunlight or light emitted by the light emitting unit 12. A first transparent body 122 or a second transparent bodyThe transparent body 124 may include Silicone (Silicone), epoxy (Epoxy), polyimide (PI), benzocyclobutene (BCB), perfluorocyclobutane (PFCB), SU8, acrylic (Acrylic Resin), polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), polyetherimide (Polyetherimide), fluorocarbon Polymer (Fluorocarbon Polymer), aluminum oxide (Al), and the like ₂ O ₃ ) SINR, or spin-on glass (SOG). The third transparent body 125 may include Sapphire (Sapphire), diamond (Diamond), glass (Glass), epoxy (Epoxy), quartz (quartz), acrylic Resin (Acrylic Resin), silicon oxide (SiO), and the like _X ) Alumina (Al) ₂ O ₃ ) Zinc oxide (ZnO), or silica gel (Silicone).

As shown in FIG. 3A, the third transparent body 125 has a shape that is wide at the top and narrow at the bottom. In detail, the third transparent body 125 has a first portion 1251 and a second portion 1252. The second portion 1252 is closer to the second transparent body 124 and has a width less than the width of the first portion 1251. The thickness of the first portion 1251 can be about 1% to 20% or 1% to 10% of the overall thickness of the third transparent body 125. In this embodiment, the junction of the first portion 1251 and the second portion 1252 is arcuate. The first portion 1251 has a side surface 1251S which is slightly inclined upward (facing upward) and is farther from the light emitting body 121 than the side surface 1241 of the second transparent body 124 to guide light to both sides of the light emitting unit 12.

In one embodiment, the light emitting unit 12A is a light emitting structure emitting light toward five surfaces (upper left, right, front, and back) and has a light emitting angle (beam angle) of about 140 degrees. Optionally, a diffusing powder can be added to the first transparent body 122, or/and the second transparent body 124, or/and the third transparent body 125. In another embodiment, the light emitting unit 12A does not include the third transparent body 125.

Fig. 3B is a schematic cross-sectional view of a light emitting unit 12B according to another embodiment of the invention. Fig. 3C is a top view of fig. 3B. The light-emitting unit in fig. 3B is similar to the light-emitting device in fig. 3A, and the same symbols or symbols correspond to elements or devices having similar or identical elements or devices. As shown in FIG. 3B, the third transparent body 125' has a frustum (frutum) shape and has a plane 1253 and a slant 1254. The design of the slope 1254 may increase the light extraction amount of the light emitting body 121 and change the light field of the light emitting unit 12. The flat 1253 and the inclined surface 1254 can enclose an angle phi between 120 degrees and 150 degrees, and the depth H1 of the inclined surface 1254 is 30% -70% or 40% -60% of the overall thickness H2 of the third transparent body 125'. As shown in FIG. 3C, the area (A1; triangle) of the flat surface 1253 may be 40% -95% or 40% -60% of the total projected area (A; diagonal) of the third transparent body 125'.

Fig. 3D shows a cross-sectional view of a light emitting unit 12D according to another embodiment of the invention. The light-emitting unit in fig. 3D is similar to the light-emitting device in fig. 3A, and the same symbols or symbols correspond to elements or devices having similar or identical elements or devices. The light emitting unit 12D further includes a reflective structure 129 formed between the first transparent body 124 and the second transparent body 125. The reflection structure 129 has a reflectivity of more than 85% for light rays incident to the reflection structure 129 within a wavelength range of 450nm to 475 nm; or has a reflectance of more than 80% at a wavelength of incident light ranging from 400nm to 600 nm. The light rays that are not reflected by the reflecting structure 129 can enter the third transparent body 125 and exit the light emitting unit 12D or the third transparent body 125 from above or from the side of the third transparent body 125. If the reflective structure 129 can reflect most light, for example, more than 95% reflectivity, the third transparent body 125 in the light emitting unit 12D can be omitted. The reflective structure 129 may be a single layer structure or a multi-layer structure. The single layer structure is, for example, a metal layer comprising, for example, silver or aluminum, or an oxide layer comprising, for example, titanium dioxide. The multilayer structure may be a stack of metal and metal oxide layers or a Distributed Bragg Reflector (DBR) to achieve the reflective effect. A stack of metal and metal oxide such as a stack of aluminum and aluminum oxide. The distributed bragg reflector may be a non-semiconductor stack or a semiconductor stack. The material of the non-semiconductor stack may be selected from one of the following groups: aluminum oxide (Al) ₂ O ₃ ) Silicon oxide (SiO) ₂ ) Titanium dioxide (TiO) ₂ ) Niobium pentoxide (Nb) ₂ O ₅ ) Silicon nitride (SiN) _x ). The material of the semiconductor stack may be selected fromOne of the following groups: gallium nitride (GaN), aluminum gallium nitride (AlGaN), aluminum indium gallium nitride (AlInGaN), aluminum arsenide (AlAs), aluminum gallium arsenide (AlGaAs), gallium arsenide (GaAs). In this embodiment, no total reflection occurs in the single-layer structure or the multi-layer structure, so at least a portion of the light directly passes through the reflective structure 129.

In another embodiment, the light emitting unit 12 in fig. 1A may have a structure similar to the

light emitting units

12A, 12B, 12D in fig. 3A, 3B, or 3D, but the phosphor layer 123 is not included in the structure. That is, the light emitting unit 12 only emits the original light from the light emitting body 121, such as red light, green light, or blue light. A plurality of phosphor particles (wavelength conversion substances) may be added in the optical structure 10 to absorb the first light emitted from the light emitting body 121 and convert the first light into a second light having a different spectrum from the first light, and the first light and the second light are mixed to generate a white light. Therefore, the light emitting device 100 can have a white light color temperature of 2200K to 6500K (e.g., 2200K, 2400K, 2700K, 3000K, 5700K, 6500K) in a thermal steady state, a color point value (CIE x, y) falling within a range of seven MacAdam ellipsoids (MacAdam ellipsoses), and a Color Rendering Index (CRI) greater than 80 or greater than 90.

The light emitting unit of the present embodiment is formed on the carrier in a flip-chip manner. In other embodiments, a plurality of horizontal or vertical light emitting units (not shown) may be fixed on the carrier by using silver paste or conductive transparent paste; then, forming electric connection between the light-emitting units by using a routing method; finally, an optical structure is provided to cover the light-emitting unit to form the light-emitting device.

Fig. 4 shows a perspective view of a lamp 30 according to an embodiment of the invention. The bulb 30 includes a lamp housing 301, a circuit board 302, a support post 303, a plurality of light emitting devices 100, a heat sink 304, and an electrical connector 305. The plurality of light emitting devices 100 are fixed and electrically connected to the support posts 303. In detail, an electrode 307 is formed on the supporting pillar 303 and electrically connected to the circuit board 302. The third electrode pad 134 of each light emitting device 100 is connected to the circuit board 302 through a metal wire 308. Since the first electrode pad 131 is electrically connected to the third electrode pad 134, the first electrode pad 131 is also electrically connected to the circuit board 302. The second electrode pad 132 of each light emitting device 100 is connected to the electrode element 307 through a metal wire 309. In the present embodiment, the light emitting devices 100 are connected in parallel through the above-mentioned electrical connection manner. In other embodiments, the light emitting devices 100 may be connected in series or in a string with each other.

FIG. 5A shows a flow chart of a method for fabricating a light emitting device according to the present invention. As shown in fig. 5A and 5B, step 501: a support 21 is provided. The support 21 has two frames 211 and a plurality of carrier plates 11 connected between the two frames 211. The carrier 11 has a circuit structure 13 thereon, and the circuit structure 13 can be formed before or after the support 21 and the carrier 11 are formed. For example, if the support 21 and the carrier 11 are formed on a single plate by using a stamping technique, the circuit structure 13 may be pre-formed on the single plate or formed on the carrier 11 after the stamping step. As shown in fig. 5A and 5C, step 502: the light emitting units 12 are fixed on the carrier plate 11 by using a Surface Mount Technology (SMT), and the light emitting units 12 are electrically connected to each other through the circuit structure 13. As shown in fig. 5A and 5D, step 503: using a mold, for example: injection molding (injection molding) or transfer molding (transfer molding) forms an optical structure 10, which encapsulates the light emitting unit 12 and the carrier 11 and exposes only the

electrode pads

131 and 132. Step 504 shown in fig. 5A and 5E: a stamping (punch) or laser cutting process is performed to separate the carrier 11 and the two frames 211, so that a plurality of independent light emitting devices 100 can be formed simultaneously or at one time.

It should be understood that the above-described embodiments of the present invention may be combined with or substituted for one another as appropriate, and are not intended to be limited to the particular embodiments shown. The examples are given only for illustrating the present invention and are not intended to limit the scope of the present invention. Any obvious modifications or alterations to the invention may be made by anyone without departing from the spirit and scope of the invention.

Claims

1. A light emitting device, comprising:

a first carrier comprising a metallic material, a planar upper surface, and a lower surface opposite the upper surface, the upper surface having a first portion and a second portion extending from the first portion;

a plurality of light emitting units arranged on the second portion, not electrically connected with the first carrier plate, and completely overlapped on the upper surface in a top view;

a first electrode pad disposed at the first portion and electrically connected to the plurality of light emitting cells;

the conducting circuit is positioned on the first carrier plate and electrically connected with at least one of the plurality of light-emitting units and the first electrode pad;

a first reflective layer on the conductive line; and

an optical structure comprising a wavelength converting substance disposed in the second portion and exposing the first portion,

wherein, in the top view, the first portion is wider than the second portion,

wherein, this optical structure contains:

a top surface above the upper surface;

a bottom surface located below the lower surface;

side surfaces extending from both ends of the top surface toward the lower surface; and a side bottom surface including a first portion and a second portion, the first portion of the side bottom surface extending from the side surface toward the bottom surface at an oblique angle, and the second portion of the side bottom surface being connected to the first portion and extending toward the bottom surface in an arc shape.

2. The light emitting device of claim 1, wherein a first brightness is measured above the top surface and a second brightness is measured below the bottom surface, and a ratio of the first brightness to the second brightness is between 2 and 9.

3. The light emitting device of claim 1, wherein the first carrier further comprises a third portion extending from the second portion and not covered by the optical structure.

4. The light emitting device of claim 1, wherein the first electrode pad is not covered by the optical structure.

5. The light emitting device of claim 1, further comprising a second electrode pad located on the same side of the first carrier as the first electrode pad.

6. The light emitting device of claim 1, further comprising a second reflective layer, the second reflective layer and the light emitting units being respectively located on opposite sides of the first carrier.

7. The light-emitting device of claim 1, wherein each of the plurality of light-emitting units has a light-emitting body and a reflective structure on the light-emitting body.

8. The light-emitting device of claim 7, further comprising a transparent structure covering the reflective structure.

9. The light emitting device of claim 7, wherein each of the plurality of light emitting units has positive and negative electrodes respectively located at opposite sides of the light emitting body with the reflective structure.