Light-emitting device and manufacturing method thereof
This disclosure discloses a light-emitting device. The light-emitting device includes a light-emitting stack with a first (top) surface, a bottom surface and at least one side surface connected to the first surface and the bottom surface, a light-reflective enclosure with a second (top) surface, a contact electrode formed on the bottom surface of the light-emitting layer, and a wavelength converting layer. Moreover, the light-reflective enclosure surrounds the side surface of the light-emitting stack and exposes to the first surface. The wavelength converting layer covers the first surface and the second surface. In addition, the second surface has a plurality of fine concave structures distributed on the second surface.
This application claims priority to and the benefit of Provisional Application Ser. No. 62/096,822 filed on Dec. 24, 2014 and TW Application Number 104128058 filed on Aug. 27, 2015, the disclosures of each which are incorporated by reference in their entireties.
BACKGROUND1. Technical Field
The present disclosure relates to a light-emitting device and manufacturing method, and in particular to a light-emitting device with a structure of a light-reflective enclosure.
2. Description of Background Art
A light-emitting diode (LED) has the characteristics of low power consumption, low heat generation, long operational life, shockproof, small volume, quick response and good opto-electrical property so the LED has been widely used in a variety of fields demanded with light-emitting elements, such as automobiles, household appliances, and lighting products, etc.
There are several ways to convert the pure light emitted from LED to another color. For example, a phosphor layer covering on the LED can convert the whole or a part of light from the LED to another color. The phosphor is a substance of photoluminescence, also known as a wavelength converting material, and it can absorb a first light emitted from the LED and emit a second light different from the first light afterward. If the first light is not absorbed completely, the remained portion of the first light can mix with the second light so as to, form a mixed light of the other color. However, ratios of light intensity of the first light and the second light (a ratio of mixed light) under different view angles are different, and as a result, the color temperatures of the mixed light under different view angles are also different.
SUMMARY OF THE DISCLOSUREThe present disclosure provides a light-emitting device including a light-emitting stack with a first (top) surface; a bottom surface and at least one side surface connected to the first surface and the bottom surface, a light-reflective enclosure with a second (top) surface, a contact electrode formed on the bottom surface of the light-emitting stack, and a wavelength converting layer. Moreover, the light-reflective enclosure surrounds the side surface of the light-emitting stack and exposes to the first surface. The wavelength converting layer covers the first surface and the second surface. In addition, the second surface has a plurality of fine concave structures distributed on the second surface.
The present disclosure provides a manufacturing method of a light-emitting device including: providing a light-emitting stack with a first (top) surface, a bottom surface and at least one side surface connected to the first surface and the bottom surface; forming a contact electrode on the bottom surface of the light-emitting stack; connecting the light-emitting stack to a temporary substrate where exposes the side surface and one of the first surface and the bottom surface; covering a light-reflective material on the exposed side surface and one of the first surface and the bottom surface; removing a portion of light-reflective material so as to expose the first surface or the bottom surface to form a light-reflective enclosure including a second surface having a plurality of fine concave structures; and removing the temporary substrate.
The present disclosure provides a light-emitting device including: a light-emitting stack with a first (top) surface, a bottom surface and at least one side surface connected to the first surface and the bottom surface; a light-reflective enclosure, having a second (top) surface, an inner sidewall, and an outer sidewall, surrounding the. side surface of the light-emitting stack, exposing the first surface, wherein the second surface protrudes outward from the inner sidewall to the outer sidewall; and a wavelength converting layer covering the first surface and the second surface.
The accompanying drawings are included to provide easy understanding of the application, and are incorporated herein and constitute a part of this specification. The drawings illustrate the embodiments of the application and, together with the description, serve to illustrate the principles of the application.
To better and concisely explain the disclosure, the same name or the same reference number given or appeared in different paragraphs or figures along the specification should has the same or equivalent meanings while it is once defined anywhere of the disclosure. In addition, these drawings are not necessarily drawn to scale. Likewise, the relative sizes of elements illustrated by the drawings may differ from the relative sizes depicted.
The following shows the description of embodiments of the present disclosure in accordance with the drawings.
The light-emitting stack 120 can be a light-emitting diode structure that converts electrical power to light energy so as to emit the first light L1. In one embodiment, the light-emitting stack 120 is flip chip type light-emitting diode structure, and includes a growth substrate (not shown), a first semiconductor layer (not shown), an active layer (not shown), and a second semiconductor layer (not shown), wherein the growth substrate can be sapphire, the first semiconductor layer can be n-type semiconductor layer, and the second semiconductor layer can be p-type semiconductor layer. The contact electrodes 122a/122b are respectively electrically connected to the first semiconductor layer and the second semiconductor layer, and electrically connect the light-emitting device 100 to external power source.
The light-reflective enclosure 140 can reflect the first light L1 emitted from the light-emitting stack 120 so of the emitted light of the light-emitting stack 120 is directed to and concentrated on the top surface 124. The light-reflective enclosure 140 can cover a part or the whole side surface 128 of the light-emitting stack 120. In one embodiment, because the light-reflective enclosure 140 covers partial or the whole side surface 128 of the light-emitting stack 120, the leakage of the first light L1 emitted from the light-emitting stack 120 from the side surface 128 is decreased. Moreover, the light-reflective enclosure 140 also covers a part of or the whole sidewall of the contact electrode 122, or is higher than the top surface 124 of the light-emitting stack 120 so as to decrease a leakage of light from the side surface 128.
A bottom position of the contact electrode 122a and/or 122b to the upper surface 142 has an average height, and the bottom position thereof to the top surface 124 also has an average height. The difference of above-mentioned two heights can be adjusted depending on optical properties. The average height is defined as the average of the height from the bottom position of the contact electrode 122a and/or 122b to the top surface 124 of the light-emitting stack 120 or the upper surface 142 of the light-reflective enclosure 140 which is measured by five positions separated with nearly the same distance from left to right. In one embodiment, a variation of two average heights is less than 40 μm. If the variation of two average heights is greater than 40 μm, a gap may be formed during the formation of the wavelength converting layer 160, the optical properties may be affected, for example, the total reflection may occur. Besides, it may induce the crack easily because the curvature of the interface between two average heights is too large.
The light-reflective enclosure 140 has a plurality of fine concave structures 142a distributed on the upper surface 142, and the fine concave structures 142a can be regularly or irregularly distributed. In one embodiment, a surface roughness of the upper surface 142 of the light-reflective enclosure 140 is greater than the top surface 124 of the light-emitting stack 120. In one embodiment, the surface roughness of the upper surface 142 has a value of Root-Mean-Square (RMS, Rq) greater than 100 nm at an area of 5 μm×5 μm. In another embodiment, RMS is ranged from 100 nm to 400 nm.
The light-reflective enclosure 140 can be composed of light-reflective material. In one embodiment, the light-reflective material can be titanium oxide (TiO2), zirconia (ZrO2), niobium oxide (Nb2O5), alumina (Al2O3), silica (SiO2), magnesium fluoride (MgF2), aluminum nitride (Al2N3) in bulk. In another embodiment, the light-reflective material is a light-reflective paste formed of above mentioned material mixed with a binding agent. The binding agent can be silicone resin, acrylic resin, or epoxy resin.
The wavelength converting layer 160 can include a transparent binder and a plurality of wavelength converting particles dispersed within the transparent binder, wherein the wavelength converting particles can absorb the first light to convert to the second light. In one embodiment, the first light to excite the wavelength converting particles is blue light emitted from the light-emitting diode, and a dominant wavelength is in the range of 430 nm to 490 nm. The wavelength converting particles absorb the first light to excite the second light which can be yellow light, and a dominant wavelength of the yellow light is in the range of 530 nm to 590 nm. The wavelength converting layer 160 can include wavelength converting particles of single material or multiple materials. In another embodiment, the wavelength converting layer 160 includes wavelength converting particles capable of emitting yellowish green light and red light.
Material of the wavelength converting particles can include inorganic phosphor, organic fluorescent colorants, semiconductors, or combinations thereof. In one embodiment, the material of the wavelength converting particles is phosphor, and the phosphor can be selected from the group consisting of Y3Al5O12, Gd3Ga5O12 Ce, (Lu, Y)3Al5O12 Ce, SrS:Eu, SrGa2S4 Eu, (Sr, Ca, Ba)(Al, Ga)2S4:Eu, (Ca, Sr)S:(Eu, Mn), (Ca, Sr)S Ce, (Sr, Ba, Ca)2Si5N8 Eu, (Sr, Ba, Ca)(Al, Ga)Si N3:Eu, (Ba, Sr, Ca)2SiO4:Eu, (Ca, Sr, Ba)Si2O2N2:Eu, K2(Si, Ti, Zr, Sn)F6:Mn and Na2(Ti, Zr)F6:Mn. The semiconductor material can include II-VI semiconductor compound, III-V semiconductor compound, IV-VI semiconductor compound, or combinations thereof. The semiconductor material further includes quantum dot material. The quantum dot material can be selected from the group consisting of ZnS, ZnSe, ZnTe, ZnO, CdS, CdSe, CdTe, GaN, GaP, GaSe, GaSb, GaAs, AlN, AlP, AlAs, InP, InAs, Te, PbS, InSb, PbTe, PbSe, SbTe, ZnCdSeS, and CuInS.
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The light-reflective enclosure 340 can increase the uniformity of color distribution under different view angles, and raise the intensity of the small angle. Furthermore, the upper surface 342 of the light-reflective enclosure 340 has the structure which protrudes outward from the inner sidewall 348 to the outer sidewall 348b so as to increase the contact area between the light-reflective enclosure 340. Moreover, the wavelength converting layer 360 can raise the bonding strength therebetween.
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The light-reflective enclosure 440 of a light-emitting device 400 of the embodiment in
The material of the transparent protecting layer 480 can use any material with properties of light transmitting and resisting external water and oxygen, such as silicone resin, epoxy resin, or glass.
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It is noted that the foregoing description has been directed to the specific embodiments of this invention. It will be apparent to those having ordinary skill in the art that other alternatives and modifications can be made to the devices in accordance with the present disclosure without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the present disclosure covers modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.
Claims
1. A light-emitting device, comprising:
- a light-emitting stack comprising a first surface, a bottom surface and at least one side surface connected to the first surface and the bottom surface;
- a light-reflective enclosure, comprising a second surface, surrounding the side surface and, exposing the first surface;
- a contact electrode formed on the bottom surface of the light-emitting stack; and
- a wavelength converting layer covering the first surface and the second surface;
- wherein the second surface comprises a plurality of fine concave structures.
2. The light-emitting device of claim 1, wherein a roughness of the first surface is smaller than a roughness of the second surface.
3. The light-emitting device of claim 1, wherein the wavelength converting layer fills the plurality of fine concave structures.
4. The light-emitting device of claim 1, wherein the wavelength converting layer comprises a thickness, and a variation of the thickness and an average thickness is less than 5%.
5. The light-emitting device of claim 1, wherein the first surface to the contact electrode has a first height and the second surface to the contact electrode has a second height, and wherein a variation of the first height and the second height is less than 40 μm.
6. The light-emitting device of claim 1, wherein a roughness of root-mean-square (RMS) of the second surface is greater than 100 nm.
7. The light-emitting device of claim 1, wherein the light-reflective enclosure comprises a light-reflective material and a binding agent.
8. The light-emitting device of claim 1, further comprising an extension pad formed on the contact electrode, and the extension pad comprises a first surface area greater than a second surface area of the contact electrode.
9. The light-emitting device of claim 1, further comprising a reflective layer surrounding the contact electrode.
10. A method of making a light-emitting device, comprising:
- providing a light-emitting stack and a contact electrode, wherein the light-emitting stack comprises a first surface, a bottom surface, and a side surface connected to the first surface and the bottom surface, and the contact electrode is formed on the bottom surface;
- connecting the light-emitting stack to a temporary substrate, and exposing the side surface and one of the first surface and the bottom surface from the temporary substrate;
- covering a light-reflective material on the side surface and one of the first surface and the bottom surface exposed from the temporary substrate;
- removing a portion of the light-reflective material to expose the first surface or the bottom surface and forming a light-reflective enclosure comprising a second surface, wherein the second surface comprises a plurality of fine concave structures distributed on the second surface; and
- removing the temporary substrate.
11. The method of making the light-emitting device of claim 10, wherein the temporary substrate exposes the first surface.
12. The method of making the light-emitting device of claim 10, further comprising covering the first surface and the second surface by a wavelength converting layer.
13. The method of making the light-emitting device of claim 10, wherein covering the light-reflective material comprises a transfer molding or a compression molding.
14. The method of making the light-emitting device of claim 10, wherein removing a portion of the light-reflective material comprises a wet blasting deflash.
15. A light-emitting device, comprising:
- a light-emitting stack comprising a first surface, a bottom surface and at least one side surface connected to the first surface and the bottom surface;
- a light-reflective enclosure, comprising a second surface, an inner sidewall, and an outer sidewall, surrounding the side surface of the light-emitting stack, exposing to the first surface, wherein the second surface comprises a first convex structure protruded outward from the inner sidewall to the outer sidewall;
- a contact electrode formed on the bottom surface of the light-emitting stack; and
- a wavelength converting layer covering the first surface and the second surface.
16. The light-emitting device of claim 15, wherein the light-reflective enclosure comprises a corner, and a position of the first convex structure corresponding to the corner.
17. The light-emitting device of claim 15, wherein a portion of the inner sidewall is lower than a portion of the outer sidewall.
18. The light-emitting device of claim 15, wherein the light-reflective enclosure further comprises a second convex structure and a flat region disposed between the first convex structure and the second convex structure.
19. The light-emitting device of claim 15, wherein the first convex structure comprises an arc-like structure.
Type: Application
Filed: Dec 22, 2015
Publication Date: Jun 30, 2016
Inventors: Chien-Liang LIU (Hsinchu), Ming-Chi HSU (Hsinchu), Jen-Chieh YU (Hsinchu)
Application Number: 14/757,365