Light emitting device

Abstract

The utility model provides a light-emitting device, which comprises an LED (light-emitting diode) chip with a light-emitting upper surface and a light-emitting side surface; the light conversion layer covers the light-emitting upper surface and the light-emitting side surface of the LED chip in a spraying manner; the appearance and the size of the light-emitting layer are matched with those of the light-emitting upper surface of the LED chip, and the light-emitting layer is formed on the surface; the first light reflecting layer is formed on one side, close to the LED chip, of the surface of the light emitting layer; the first light reflecting layer partially covers the light-emitting layer, a light-emitting area in a preset shape is reserved on the surface of the light-emitting layer, and the light-emitting area is a circular area located in the center of the light-emitting upper surface of the LED chip; or the light-emitting area is a regular octagon located in the center of the light-emitting upper surface of the LED chip and a regular polygon area with more than eight sides; and the light blocking glue layer covers the light-emitting side surface of the LED chip, the side surface of the light conversion layer and the side surface of the light emitting layer. Areas outside the light-emitting area on the surface of the light-emitting layer are covered by the first light reflecting layer to avoid light transmission, and the light does not need to be cut into a special shape through laser.

Description

TECHNICAL FIELD

[0001] The utility model relates to a semiconductor technical field especially a light emitting device. BACKGROUND

[0002] In the lighting field, such as flashlight and stage light, etc. need to gather light into light column to irradiate the application of long distance, usually adopt the thin film LED chip of vertical structure. The mainstream chip design on the market at present is more for square light emitting surface, and its advantage lies in that effective light emitting area is larger, and it can provide higher light output. However, this design also has a disadvantage, that is, the length of the diagonal direction is greater than that of the side, which can lead to the unevenness of the light spot shape.

[0003] In order to overcome this problem, the market also launched the vertical structure LED chip of circular light emitting surface. The advantage of this design is that it can produce a circular light spot with clear boundary and regular shape, but the processing and packaging process is more complex than the traditional square structure, and it needs higher equipment precision and process control, and there are problems such as significant increase of production cost.

[0004] With the continuous progress of technology, there also appears an innovative scheme of circular light emitting surface using flip chip technology. One of the methods is to paste a circular fluorescent sheet on the flip chip, and fill the part outside the circular area with high reflectivity white glue to enhance the concentration and reflection efficiency of light. Another scheme is to form a circular light emitting area on the light emitting upper surface of the flip chip by filling high reflectivity white glue. These technical schemes not only optimize the shape and quality of the light spot, but also improve the light efficiency and reliability of the product, and meet the stringent requirements of high-end lighting market on performance. However, there are still some technical challenges:

[0005] In the technical scheme of pasting circular fluorescent sheet on flip chip: 1) the processing cost of circular fluorescent sheet is high, and laser cutting is needed, which can cause edge ablation phenomenon, thereby affecting the light efficiency and reliability under large current; 2) although the part outside the circular area is filled with high reflectivity white glue, under the condition of large current, light may still penetrate through the white glue, thereby reducing the light efficiency. If the fluorescent sheet is designed to be too thick, although the light spot uniformity can be improved, the overall brightness will be reduced. INVENTION CONTENTS

[0006] In order to overcome the above shortcomings, the utility model provides a light emitting device, which effectively improves the light spot uniformity, light emitting brightness and the like of the existing long distance irradiation light emitting device.

[0007] The technical scheme provided by the utility model comprises:

[0008] The utility model provides a light emitting device, which comprises:

[0009] LED chip, having a light emitting upper surface and a light emitting side surface;

[0010] light conversion layer, covering the light emitting upper surface and the light emitting side surface of the LED chip by spraying;

[0011] light emitting layer, formed on the surface of the light emitting layer and having a size suitable for the light emitting upper surface of the LED chip;

[0012] first light reflection layer, formed on the surface of the light emitting layer close to the LED chip; the first light reflection layer partially covers the light emitting layer, leaving a preset shape of light emitting area on the surface of the light emitting layer; the light emitting area is a circular area located at the center of the light emitting upper surface of the LED chip; or the light emitting area is a regular octagonal area located at the center of the light emitting upper surface of the LED chip or a regular polygonal area with a side number greater than eight;

[0013] light blocking glue layer, covering the light emitting side surface of the LED chip, the side surface of the light conversion layer and the side surface of the light emitting layer.

[0014] The light emitting device provided by the utility model can at least bring the following beneficial effects:

[0015] 1) Compared with the technical solution of forming a circular light emitting area by high reflectivity white glue, the first light reflection layer / second light reflection layer can greatly improve the light reflection of the part outside the circular area of the light emitting upper surface of the LED chip, effectively solve the problem of incomplete light blocking of high reflectivity white glue in the prior art, thereby improving the light emitting performance of the light emitting device, reducing the maximum distance of the light emitting points in the light emitting device (reducing the distance of the light emitting points within a certain range), and improving the beam center density.

[0016] 2) In the preparation of a single light emitting layer (the surface is formed with the first light reflection layer / second light reflection layer) with a size suitable for the light emitting upper surface of the LED chip, the light emitting layer can be obtained by blade cutting, which can reduce the cost to a certain extent compared with laser cutting; and the edges of the light emitting layer will not appear ablation phenomenon, thereby further improving the light emitting efficiency of the light emitting device. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a cross-sectional view of the light emitting layer and the first light reflection layer in an embodiment of the utility model;

[0018] Figure 2 is Figure 1 is a bottom view of the light emitting layer and the first light reflection layer in an embodiment of the utility model;

[0019] Figure 3 is a cross-sectional view of the light emitting device in an embodiment of the utility model;

[0020] Figure 4 isFigure 3 a top view of a light emitting device;

[0021] Figure 5 a cross-sectional view of a light emitting device according to another embodiment of the present application;

[0022] Figure 6 a cross-sectional view of a light emitting layer with light reflection layers on both sides according to another embodiment of the present application.

[0023] Reference signs:

[0024] 10 - LED chip, 11 - light emitting upper surface, 12 - light conversion layer, 20 - light emitting layer, 30 - first light reflection layer, 31 - protective layer, 32 - second light reflection layer, 40 - light blocking layer, 50 - packaging substrate, 60 - lens. DETAILED DESCRIPTION

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, specific embodiments of the present application will be described below with reference to the drawings. Obviously, the drawings described below are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained from these drawings without creative labor, and other embodiments can also be obtained.

[0026] An embodiment of the present application is a light emitting device, comprising: an LED chip having a light emitting upper surface and a light emitting side surface; a light conversion layer covering the light emitting upper surface and the light emitting side surface of the LED chip by spraying; a light emitting layer having a size and shape suitable for the light emitting upper surface of the LED chip and formed on the surface thereof; a first light reflection layer formed on one side of the surface of the light emitting layer close to the LED chip; the first light reflection layer partially covers the light emitting layer, and a light emitting area of a predetermined shape is reserved on the surface of the light emitting layer, the light emitting area being a circular area located at the center of the light emitting upper surface of the LED chip; or the light emitting area being a regular octagonal area located at the center of the light emitting upper surface of the LED chip and a regular polygonal area with a side number greater than eight; and a light blocking adhesive layer covering the light emitting side surface of the LED chip, the side surface of the light conversion layer and the side surface of the light emitting layer.

[0027] In the embodiment, the LED chip can be selected from flip-chip structures with a size of 20 mil x 20 mil to 160 mil x 160 mil, wherein the upper light-emitting surface is used for light emission, and no electrode or other structure is arranged, and the shape is generally square. When the wafer is cut into an independent LED chip, no special shape design is required. The electrode of the flip-chip is arranged on the side surface opposite to the upper light-emitting surface, and an epitaxial layer structure is formed inside the LED chip. After a proper voltage is applied to the LED chip through the electrode, photons are generated in the epitaxial layer and emitted from the upper light-emitting surface and the light-emitting side surface. Here, the light-emitting color of the LED chip itself can be violet, green or blue, and the structure of the epitaxial layer can be designed according to actual needs by those skilled in the art, which is not limited in the embodiment. When the LED chip is packaged, a ceramic substrate or the like can be selected as the packaging substrate. In order to obtain a light-emitting device with clear boundaries and uniform light spots, on the one hand, the light generated by the epitaxial layer should be prevented from being emitted from the light-emitting side surface, i.e., the light should only be emitted from the upper light-emitting surface; on the other hand, since the shape of the square upper light-emitting surface is not uniform (the length of the diagonal direction is greater than that of the side direction), the light-emitting shape of the upper light-emitting surface should also be controlled to obtain a more uniform light-emitting shape.

[0028] For the light emission of the epitaxial layer in the LED chip to the light-emitting side surface, the light-blocking adhesive layer is used to reflect the light in the light-emitting device. The light-blocking adhesive layer is arranged on the periphery of the LED chip and covers the light-emitting side surface from the side to reflect the light to the upper light-emitting surface. The light-blocking adhesive layer has high reflectivity and is generally prepared by mixing silicone and light-reflecting particles or by mixing resin and light-reflecting particles. The resin can be a thermosetting resin such as epoxy resin, thermosetting polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, thermosetting polyurethane resin, etc., and is preferably a thermosetting silicone resin or an epoxy resin. The light-reflecting particles are generally white inorganic pigments such as titanium oxide, zinc oxide, zirconium oxide, lead white (lead carbonate), calcium carbonate, clay minerals such as kaolin (kaolinite), etc., and are preferably titanium oxide, which is doped in the resin at a suitable concentration to make the light-blocking adhesive layer have high reflectivity, such as 85% or more, 90% or more, etc. The light-blocking adhesive layer can further extend upward to cover the side surface of the light conversion layer, the light-emitting layer and the first light-reflecting layer, further preventing light emission from the side surface.

[0029] The light conversion layer is made of silicone and fluorescent materials. It allows light to be excited into the desired color before being emitted. During fabrication, the light conversion layer is formed on the upper and lower light-emitting surfaces of the LED chip by spraying. Before spraying, appropriate amounts of phosphor, silicone, and a diluent (such as o-xylene) are uniformly mixed, sprayed onto the LED chip surface, and then cured. The diluent evaporates, and the phosphor precipitates near the upper light-emitting surface of the LED chip. Compared to attaching a fluorescent film to the LED chip surface, this method can improve the luminous efficiency and current resistance of the light-emitting device to a certain extent.

[0030] The shape and size of the light-emitting layer are adapted to the upper surface of the LED chip. Its size is at least the same as the upper surface of the LED chip, or it can be slightly larger. After the light-emitting layer is attached to the upper surface of the LED chip, its edges slightly extend beyond it. It is made of transparent material. For high-power light-emitting devices, glass or similar materials can be used; for low-to-medium power light-emitting devices, materials such as silicone can be used.

[0031] To address the light emission shape of the upper surface of an LED chip, the light-emitting device utilizes a combination of a light-emitting layer and a first reflective layer to alter the light emission shape. The first reflective layer is deposited on the surface of the light-emitting layer and covers a portion of its area, ensuring that light is emitted only from the uncovered area, effectively optimizing the light spot shape. It should be noted that the first reflective layer, utilizing the total internal reflection properties of metal, is formed on the surface of the light-emitting layer, located on the side closest to the LED chip, and only covers a portion of the surface, such as... Figure 1 and Figure 2 ( Figure 1 for Figure 2 As shown in the cross-sectional diagram along AA, the first light-reflecting layer 30 does not cover the entire surface of the light-emitting layer 20, but rather covers the four corners of the square light-emitting layer 20, reserving a central circular area for light emission. Within the covered area, the first light-reflecting layer 30 achieves total internal reflection of the light emitted from the LED chip; that is, light cannot pass through the area covered by the first light-reflecting layer 30 to create a halo effect. The light from the emitting surface is emitted only from the area not covered by the first light-reflecting layer, resulting in a clear overall light spot boundary. Simply attaching the light-emitting layer coated with the first light-reflecting layer to the surface of the light conversion layer optimizes the light spot shape of the light-emitting device. Furthermore, the first light-reflecting layer is relatively thin, deposited on the surface of the light-emitting layer, and does not affect the original light emission angle of the emitting surface of the LED chip. To ensure the total internal reflection performance of the first light-reflecting layer, it is a metal reflective layer, which can be formed using a metal with high reflectivity, such as Al or Ag, without specific limitations. The thickness is 0.1µm-2µm.

[0032] To further improve the reflection performance of the first light reflection layer, the first light reflection layer can also be configured to be composed of a first reflection layer and a second reflection layer stacked together, the first reflection layer is prepared from periodically stacked low refractive index insulating oxide material and high refractive index insulating oxide material (the layer closest to the light emitting layer is prepared from low refractive index insulating oxide material), to reflect the light emitted by the LED chip in a specific waveband. Specifically, the low refractive index material can be selected from SiO2, MgF2, Al2O3 and other low refractive index insulating materials, and the high refractive index material can be selected from TiO2, Nb2O5 and other high refractive index insulating materials. The second reflection layer is a metal reflection layer plated on the surface of the first reflection layer, which is preferably formed on the surface of the light emitting layer to avoid metal peeling. The period of the low refractive index insulating oxide material and the high refractive index insulating oxide material in the first reflection layer is greater than 1 and not more than 10, and the thickness of a single layer film (low refractive index film layer or high refractive index film layer) is 0.04 µm~1 µm.

[0033] For the entire light emitting device after encapsulation, as shown in Figure 3 and Figure 4 ( Figure 3 For Figure 4 the cross-sectional view along B-B), the LED chip 10 is encapsulated on the surface of the packaging substrate 50, the light generated by the LED chip 10 inside is converted by the sprayed light conversion layer 12 and excited into the required light color before being emitted externally, and the light is prevented from being emitted from the light emitting side due to the light blocking glue layer 40 on the side. At the same time, the upper surface of the light conversion layer 12 above the light emitting upper surface 11 is provided with the light emitting layer 20 plated with the first light reflection layer 30, and the first light reflection layer is close to the light conversion layer, so that the required light can only be emitted from the uncovered area of the first light reflection layer, that is, the light emitting device only emits light from Figure 4The center circular area of the shown light emitting layer emits light. The uncovered area of the light emitting layer surface by the first light reflecting layer is the preset light emitting area, and the whole light emitting device only emits light from this area. Only the corresponding shape area needs to be designed and reserved in the first light reflecting layer according to the required light spot shape, so that the corresponding shape of the light emitting layer surface is exposed to the outside to emit light. The light emitting layer is made of transparent material, and the shape and size of the light emitting area can be configured according to actual needs. For example, in order to make the light spot boundary clear and the overall light emission uniform, the light emitting area is configured as a circular area located at the center of the light emitting upper surface of the LED chip, that is, the first light reflecting layer covers the area of the light emitting layer close to the LED chip except the circular area, and the light is emitted from the circular area to form a clear and uniform light spot. The light emitting area can also be configured as a regular octagonal area located at the center of the light emitting upper surface of the LED chip, that is, the first light reflecting layer covers the area of the light emitting layer close to the LED chip except the regular octagonal area, and the light is emitted from the regular octagonal area to also form a clear and uniform light spot. In order to improve the light emitting efficiency of the light emitting device, the largest area light emitting area can be designed based on the shape of the light emitting upper surface of the LED chip, such as Figure 1 and 2 As shown in the figure, the largest inscribed circle is formed on the square light emitting upper surface as the light emitting area. In this example, compared with the light emitting device without the first light reflecting layer, the circular light emitting area can be reduced to 1 / 2 (the light emitted by the LED chip of the square light emitting surface is approximately circular due to the influence of the four corners, and the diameter of the circular light spot is the length of the diagonal; after plating the first light reflecting layer, the diameter of the circular light spot is the length of the side of the LED chip), thereby improving the beam center density. The light emitting area can even be configured as a regular nonagon, a regular decagon or other regular polygonal area closer to a circle located at the center of the light emitting upper surface of the LED chip. In actual application, as shown in the figure, Figure 5 A lens 60 can also be further configured on the top of the light emitting device to collect light and enhance the irradiation effect.

[0034] Compared with the scheme using a circular fluorescent sheet, the light emitting layer in the embodiment is a square consistent with the light emitting upper surface, and does not need to be cut into a special shape by laser. The preparation process only needs to be cut by a blade, which not only has lower cost, but also avoids the ablation problem caused by laser cutting. In addition, in the embodiment, the area outside the light emitting area is covered by the first light reflecting layer to avoid light transmission. Compared with the way of using high reflectivity white glue to avoid light emission in the area outside the circle, the reflection performance is more excellent, especially under large current, which can also effectively prevent light transmission. The light cannot penetrate the area covered by the first light reflecting layer to cause light halo, and the overall light spot boundary is clear.

[0035] The above embodiment is improved to obtain the present embodiment, in which the light-emitting layer is made of transparent material, and a second light-reflecting layer is further formed on the surface of the light-emitting layer away from the LED chip, and the same light-emitting area as the first light-reflecting layer is reserved.

[0036] In order to further improve the light-emitting efficiency of the light-emitting device, in the present embodiment, after the first light-reflecting layer is arranged on one side of the transparent light-emitting layer, a second light-reflecting layer is arranged on the other side, that is, the light-reflecting layers are arranged on both sides of the light-emitting layer, and the same size and shape of light-emitting area are reserved in the two light-reflecting layers. Like the first light-reflecting layer, the second light-reflecting layer can also be a metal reflecting layer, such as Al, Ag, etc.; or the second light-reflecting layer includes a first reflecting layer and a second reflecting layer, the first reflecting layer is made of periodically stacked low refractive index insulating oxide material (SiO2, MgF2, Al2O3, etc.) and high refractive index insulating oxide material (TiO2, Nb2O5, etc.), and the layer closest to the light-emitting layer is made of low refractive index insulating oxide material, and the second reflecting layer is a metal reflecting layer plated on the surface of the first reflecting layer. In practical application, the materials of the light-reflecting layers on both sides can be the same or different, for example, the first light-reflecting layer and the second light-reflecting layer are both metal reflecting layers; for another example, the first light-reflecting layer is composed of the first reflecting layer and the second reflecting layer, and the second light-reflecting layer is a metal reflecting layer.

[0037] In order to improve the stability of the light-emitting device and prevent the oxidation of the metal reflecting layer, the light-emitting device further includes a protective layer, which covers the second light-reflecting layer and is formed on the surface of the light-emitting layer, and the coverage range is consistent with the second light-reflecting layer, that is, the same shape of light-emitting area is reserved. Figure 6 As shown in the figure, the light-reflecting layers are plated on both sides of the light-emitting layer, the protective layer 31 covers the surface of the second light-reflecting layer 32, and the protective layer 31 also reserves the light-emitting area of the preset shape consistent with the second light-reflecting layer 32 and the first light-reflecting layer 30, which plays a protective role while not affecting the light emission. The protective layer can be made of oxide (such as SiO2, etc.) or metal stack of Ti / Au, Ni / Au, Ni / Pt

[0038] Another embodiment of the present application is a light-emitting device preparation method applied to the above light-emitting device, which comprises the following steps:

[0039] S10, a pre-prepared light-emitting layer is provided, the shape of the light-emitting layer is adapted to the light-emitting upper surface of the LED chip to form the surface thereof, and a first light-reflecting layer is formed on one side surface; the first light-reflecting layer partially covers the light-emitting layer, and a light-emitting area of a preset shape is reserved, the light-emitting area is a circular area located at the center of the light-emitting upper surface of the LED chip; or the light-emitting area is a regular octagonal area located at the center of the light-emitting upper surface of the LED chip and a regular polygonal area with a side number greater than eight.

[0040] The shape and size of the light emitting layer provided in advance here are adapted to the light emitting upper surface of the LED chip, and at least the same size as the light emitting upper surface of the LED chip, that is, the same as the light emitting upper surface of the LED chip or larger than the light emitting upper surface. After the light emitting layer is attached to the light emitting upper surface of the LED chip, the edge position slightly exceeds. The light emitting layer is made of transparent material, and if applied to a high-power light emitting device, glass or the like can be selected; if applied to a small-power light emitting device, materials such as silicone can be selected. Regardless of the material of the light emitting layer, a first light reflection layer is formed on one side surface in order to optimize the light spot of the light emitting device. It should be noted that the first light reflection layer is formed on the surface of the light emitting layer away from the LED chip by using the total reflection performance of the metal, and only covers part of the surface of the light emitting layer, not the whole surface. In the covered area, the first light reflection layer realizes total reflection of the light emitted from the light emitting layer, that is, the light cannot pass through the area covered by the first light reflection layer to cause light halo, and the light from the light emitting upper surface is only emitted from the area not covered by the first light reflection layer, and the overall light spot boundary is clear.

[0041] In an example, before the light emitting layer is attached to the LED chip, the preparation process of the light emitting layer and the first light reflection layer includes the following steps:

[0042] S01 Provide a full-surface light emitting layer.

[0043] According to actual needs, the full-surface light emitting layer is made of transparent material, and if applied to a high-power light emitting device, glass or the like can be selected; if applied to a small-power light emitting device, materials such as silicone can be selected.

[0044] S02 Form a first light reflection layer on one side surface of the light emitting layer.

[0045] In order to ensure the total reflection performance of the first light reflection layer, the first light reflection layer is a metal reflection layer, which can be formed of a metal with high reflectivity, such as Al, Ag, etc., which is not limited here. In order to further improve the reflection performance of the first light reflection layer, the first light reflection layer can also be composed of a first reflection layer and a second reflection layer stacked together, the first reflection layer is made of periodically stacked low refractive index insulating oxide material and high refractive index insulating oxide material (the layer closest to the light emitting layer is made of low refractive index insulating oxide material), to reflect the light of a specific waveband emitted by the LED chip. Specifically, the low refractive index material can be selected from SiO2, MgF2, Al2O3, and other insulating materials with low refractive index, and the high refractive index material can be selected from TiO2, Nb2O5, and other insulating materials with high refractive index. The second reflection layer is a metal reflection layer plated on the surface of the first reflection layer, and the metal reflection layer is preferably formed on the surface of the light emitting layer to avoid metal peeling.

[0046] S03 etching the light-emitting layer plated with the first light reflection layer to reserve a preset shape of light-emitting area.

[0047] Since the light can only be emitted from the uncovered area of the first light reflection layer, the uncovered area of the first light reflection layer on the surface of the light-emitting layer is the preset light-emitting area, and the entire light-emitting device emits light only from this area. Therefore, only a corresponding shape of area needs to be designed and reserved in the first light reflection layer to expose the corresponding shape of the light-emitting layer surface to the outside. The entire light-emitting layer is subsequently segmented into multiple independent light-emitting layers with the same size as the light-emitting upper surface of the LED chip. Therefore, during the etching process, a corresponding etching pattern should be designed for each independent light-emitting surface according to the preset segmentation rule to form a corresponding light-emitting area. The etching process can use conventional dry etching, wet etching, etc. as long as it can achieve the purpose of the utility model.

[0048] The shape and size of the light-emitting area can be configured according to actual needs. For example, in order to make the light spot boundary clear and the overall light emission uniform, the light-emitting area can be configured as a circular area located at the center of the light-emitting upper surface of the LED chip, i.e., the first light reflection layer covers the area on the side of the light-emitting layer close to the LED chip except the circular area, and the light is emitted from the circular area to form a light spot with clear boundary and uniform light emission. The light-emitting area can also be configured as a regular octagonal area located at the center of the light-emitting upper surface of the LED chip, i.e., the first light reflection layer covers the area on the side of the light-emitting layer close to the LED chip except the regular octagonal area, and the light is emitted from the regular octagonal area to form a light spot with clear boundary and uniform light emission. In order to improve the light-emitting efficiency of the light-emitting device, the largest area of the light-emitting area can be designed based on the shape of the light-emitting upper surface of the LED chip, such as forming the largest inscribed circle on the square light-emitting upper surface as the light-emitting area, etc. Figure 1 and 2

[0049] S04 cutting the entire light-emitting layer using a blade to obtain a single light-emitting layer with a size that matches the light-emitting upper surface of the LED chip.

[0050] The light-emitting layer in this embodiment is a square that matches the light-emitting upper surface. During preparation, the blade is used for cutting, which not only has lower cost but also avoids the ablation problem caused by laser cutting.

[0051] S20 fixing the LED chip on the surface of the packaging substrate, with the light-emitting upper surface of the LED chip facing upwards and the light-emitting upper surface and the light-emitting side being sprayed with a light conversion layer.

[0052] ​The LED chip can be selected as a flip chip with a size of 20 mil x 20 mil to 160 mil x 160 mil, wherein the upper light-emitting surface is used for light emission, no electrode or other structure is arranged, and the shape is square. When the wafer is cut into an independent LED chip, no special shape design is needed. The electrode of the flip chip is arranged on the surface opposite to the upper light-emitting surface. The epitaxial layer structure is formed in the LED chip. After the LED chip is applied with a proper voltage through the electrode, photons are generated in the epitaxial layer and emitted from the upper light-emitting surface and the light-emitting side. The light-emitting color of the LED chip itself can be violet, green or blue, and the structure of the epitaxial layer can be designed according to actual needs by a person skilled in the art, which is not limited in the embodiment. The packaging substrate can be selected as a ceramic substrate. The light conversion layer is prepared from silica gel and fluorescent material, so that the light is excited to the required light color by the light conversion layer and then emitted to the outside. In the preparation process, the light conversion layer is formed on the upper light-emitting surface and the light-emitting side covering the LED chip by spraying. Before spraying, the fluorescent powder, silica gel and diluent (such as o-xylene) are uniformly mixed, sprayed on the surface of the LED chip and then solidified. The diluent volatilizes, and the fluorescent powder precipitates close to the upper light-emitting surface of the LED chip, thereby improving the light efficiency and current resistance of the light-emitting device.

[0053] S30 The light-emitting surface of the LED chip is pasted with a light-emitting layer, and the side of the light-emitting layer with the first light reflection layer is close to the LED chip.

[0054] The shape and size of the light-emitting layer are adapted to the upper light-emitting surface of the LED chip, and the center of the light-emitting layer is correspondingly arranged with the center of the upper light-emitting surface of the LED chip. During the mounting process, the light-emitting layer can be pasted by using adhesive. The adhesive is selected from high-transparency materials, such as epoxy resin, thermosetting polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, thermosetting polyurethane resin and other thermosetting resins.

[0055] S40 A light-blocking glue layer is formed around the LED chip, the light-blocking glue layer covers the light-emitting side and the side of the light-emitting layer of the LED chip, and a light-emitting device is obtained.

[0056] For the light emission of the epitaxial layer in the LED chip to the light emitting side, the light blocking glue layer is used to reflect the light in the light emitting device. The light blocking glue layer is arranged on the periphery of the LED chip, at least from the side to cover the light emitting side and the side of the light emitting layer, so as to reflect it to the light emitting surface. The light blocking glue layer has high reflectivity, which is generally prepared by mixing silica gel and light reflecting particles, or by mixing resin and light reflecting particles. Among them, the resin can be epoxy resin, thermosetting polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, thermosetting polyurethane resin and other thermosetting resins, preferably thermosetting silicone resin and epoxy resin. The light reflecting particles are generally white inorganic pigments, such as titanium oxide, zinc oxide, zirconium oxide, lead white (lead carbonate), calcium carbonate, clay minerals such as kaolin (kaolinite), etc., preferably titanium oxide, which is doped in the resin at a suitable concentration to make the light blocking glue layer have high reflectivity, such as more than 85%, more than 90%, etc. In addition to covering the light emitting side, the light blocking glue layer can further extend upwards to cover the side of the light emitting layer and the first light reflecting layer, further preventing the side light emission. In practical application, a lens can be further configured on the top of the light emitting device to collect light.

[0057] The above embodiment is improved to obtain the present embodiment. In the present embodiment, when the light emitting layer is prepared from a transparent material, the other side surface of the light emitting layer is formed with a second light reflecting layer. Before providing the prepared light emitting layer, the steps of preparing the first light reflecting layer and the second light reflecting layer on the surface of the light emitting layer are further included:

[0058] S05 providing a full-surface light emitting layer.

[0059] The light emitting layer is prepared from a transparent material, such as glass, transparent glue, etc.

[0060] S06 forming a first light reflecting layer and a second light reflecting layer on the two side surfaces of the light emitting layer, respectively.

[0061] The second light reflection layer can be a metal reflection layer, such as Al, Ag, etc., or the second light reflection layer comprises a first reflection layer and a second reflection layer, the first reflection layer is made of periodically stacked low refractive index insulating oxide material (SiO2, MgF2, Al2O3, etc.) and high refractive index insulating oxide material (TiO2, Nb2O5, etc.), and the layer closest to the light emitting layer is made of low refractive index insulating oxide material, and the second reflection layer is a metal reflection layer plated on the surface of the first reflection layer. In practical applications, the materials of the two light reflection layers can be the same or different, for example, the first light reflection layer and the second light reflection layer are both metal reflection layers; for example, the first light reflection layer is composed of a first reflection layer and a second reflection layer, and the second light reflection layer is a metal reflection layer. In order to improve the stability of the light emitting device and prevent the metal reflection layer from oxidizing, a protective layer can be further provided on the surface of the second light reflection layer, and the protective layer has a light emitting area with a preset shape consistent with the first light reflection layer and the second light reflection layer, which plays a protective role while not affecting light emission. The protective layer can be made of oxide (such as SiO2, etc.) or metal stack of Ti / Au, Ni / Au, Ni / Pt.

[0062] S07 Etching the light emitting layer plated with the first light reflection layer and the second light reflection layer to reserve a light emitting area with a preset shape.

[0063] The etching process can be conventional dry etching, wet etching, etc., as long as it can achieve the purpose of the utility model. When the protective layer is formed, the first light reflection layer and the second light reflection layer, and the protective layer are etched synchronously to form a consistent light emitting area.

[0064] S08 Using a blade to cut the entire light emitting layer to obtain a single light emitting layer with a size suitable for the light emitting upper surface of the LED chip.

[0065] It should be noted that the above embodiments can be freely combined as needed. The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should be considered as the protection scope of the present application.

Claims

1. A light emitting device, characterized by, The application relates to a light-emitting device, comprising: an LED chip having a light-emitting upper surface and a light-emitting side surface; a light conversion layer covering the light-emitting upper surface and the light-emitting side surface of the LED chip by spraying; a light-emitting layer formed on the surface of the light-emitting layer and having the same size as the light-emitting upper surface of the LED chip; a first light reflection layer formed on the surface of the light-emitting layer close to the LED chip, the first light reflection layer partially covering the light-emitting layer and leaving a preset light-emitting area on the surface of the light-emitting layer, the light-emitting area being a circular area located at the center of the light-emitting upper surface of the LED chip or being a regular octagonal area or a regular polygonal area with a side number greater than eight located at the center of the light-emitting upper surface of the LED chip; a light-blocking glue layer covering the light-emitting side surface of the LED chip, the side surface of the light conversion layer and the side surface of the light-emitting layer.

2. The light-emitting device of claim 1, wherein: the light-emitting layer is made of a transparent material, and the LED chip emits light through the light-emitting area left by the first light reflection layer on the surface of the light-emitting layer.

3. The light-emitting device of claim 2, wherein: a second light reflection layer is formed on the part of the surface of the light-emitting layer far from the LED chip, and the same light-emitting area as the first light reflection layer is left.

4. The light-emitting device of claim 3, wherein: the first light reflection layer or the second light reflection layer is a metal reflection layer; or the first light reflection layer or the second light reflection layer comprises a first reflection layer and a second reflection layer, the first reflection layer is made of periodically stacked low-refractive insulating oxide material and high-refractive insulating oxide material, and the layer closest to the light-emitting layer is made of low-refractive insulating oxide material, and the second reflection layer is a metal reflection layer plated on the surface of the first reflection layer.

5. The light-emitting device of claim 3 or 4, wherein: the light-emitting device further comprises a protective layer, the protective layer is formed on the surface of the light-emitting layer and covers the second light reflection layer, and the preset light-emitting area is left in the protective layer.

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