An LED light emitting device

Abstract

The utility model provides a kind of LED light emitting device, comprising: substrate and the LED chip of being located on substrate;Light-transmitting adhesive layer, light-transmitting adhesive layer is wrapped in the four around and upper surface of LED chip, the upper surface of light-transmitting adhesive layer is the curved surface of central concave, curved surface has fixed curvature;Reflective layer, covers the upper surface of light-transmitting adhesive layer.Light-transmitting adhesive layer completely wraps the four around and upper surface of LED chip, its upper surface is the curved surface structure of central concave.And upper surface is further provided with the reflective layer of high reflectivity, so that the light that is emitted to the positive upwards is deflected to the four around by the refraction of curved surface, the concave surface of central region can disperse originally concentrated strong light, the curved surface of edge region then guides light to outside light supplement, realizes efficient lateral light emission, applicable to small and medium size backlight module.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor technology, and in particular to an LED light-emitting device. Background Technology

[0002] LED chips typically exhibit a Lambertian light pattern, with high luminous intensity at the center and decreasing intensity further away from the center. In backlighting, Lambertian light emission is prone to uneven light emission, resulting in high brightness in the center and low brightness around the edges. Therefore, side-emitting LED chips are often used. In existing technologies, a reflective layer is formed on the surface of the LED chip's encapsulation layer to reflect light emitted directly upwards. However, this structure has low reflection efficiency, and the light is easily absorbed after multiple reflections within the encapsulation, resulting in reduced light emission efficiency. Utility Model Content

[0003] To overcome the above shortcomings, this utility model provides an LED light-emitting device that achieves efficient side light emission.

[0004] The technical solution provided by this utility model is as follows: This utility model provides an LED light-emitting device, comprising: Substrate and LED chip disposed on substrate; A light-transmitting adhesive layer is wrapped around the LED chip and on its upper surface. The upper surface of the light-transmitting adhesive layer is a concave curved surface with a fixed curvature. The reflective layer covers the upper surface of the light-transmitting adhesive layer.

[0005] The LED light-emitting device provided by this utility model has a light-transmitting adhesive layer that completely covers the LED chip around its perimeter and upper surface. The upper surface has a concave curved structure in the center. Furthermore, a high-reflectivity reflective layer is provided on the upper surface, so that light emitted directly upwards is refracted by the curved surface and deflected in all directions. The concave surface in the central area can disperse the originally concentrated strong light, while the curved surface in the edge area guides the light outward to supplement the light, changing the original Lambertian light emission mode of the LED chip and realizing more lateral light emission. It is suitable for small and medium-sized backlight modules. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the structure of an LED light-emitting device in one embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a vertical LED light-emitting device in one embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of an upright LED light-emitting device in one embodiment of the present invention; Figure 4This is a schematic diagram of the structure of an LED light-emitting device with a curved upper surface of the reflective layer in one embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of an LED light-emitting device having a fluorescent layer and white glue formed in one embodiment of the present invention; Figure 6 This is a schematic diagram of an LED light-emitting device having a fluorescent layer and a second fluorescent layer formed in one embodiment of the present invention.

[0007] Figure label: 10-Substrate, 20-LED chip, 21-Light-emitting surface, 22-Bonding wire, 23-Phosphor layer, 24-White adhesive, 25-Second phosphor layer, 30-Transparent adhesive layer, 40-Reflective layer. Detailed Implementation

[0008] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the specific implementation methods of this utility model will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are merely some embodiments of this utility model. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0009] One embodiment of this utility model discloses an LED light-emitting device, comprising: a substrate and an LED chip disposed on the substrate; a light-transmitting adhesive layer, which wraps around the LED chip and its upper surface, the upper surface of which is a concave curved surface with a fixed curvature; and a reflective layer covering the upper surface of the light-transmitting adhesive layer. The substrate is flat, providing mechanical support and circuit connection for the LED chip. A circuit pattern electrically connected to the LED chip is formed on the substrate surface. The substrate can be made of materials such as planar epoxy molding compound (EMC), sheet molding compound (SMC), Al2O3 ceramic, or AlN ceramic. The substrate can be transparent or opaque; in practical applications, those skilled in the art can flexibly select a suitable substrate according to actual needs, and this embodiment does not impose specific limitations in this regard.

[0010] The LED chip is positioned on the substrate with its light-emitting surface facing upwards. It can be any of a blue, green, or red LED chip, as long as it can emit light normally after applying a suitable voltage. It can be any of a vertical, flip-chip, or upright structure. In a vertical structure, one of a positive and a negative electrode is located on the light-emitting surface, and the other electrode is located on the opposite side. During die bonding, the electrode on the light-emitting surface is electrically connected to the substrate's solder joints via bonding wires. In a flip-chip structure, there is no electrode on the light-emitting surface; both the positive and negative electrodes are located on the opposite side. During die bonding, both electrodes are directly soldered to the substrate's solder joints without the need for bonding wires. In an upright structure, both a positive and a negative electrode are present on the light-emitting surface, and both electrodes are electrically connected to different solder joints on the substrate via bonding wires. In practical applications, those skilled in the art can choose which chip to use based on the application scenario.

[0011] The light-transmitting adhesive layer has good light transmittance and is made of silicone or resin. The resin can be silicone resin, epoxy resin, thermosetting polyimide resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, thermosetting polyurethane resin, etc., with thermosetting silicone resin and epoxy resin being preferred. It is prepared using compression molding or injection molding processes. A mold with a recessed center on the upper surface is pre-prepared, and the upper surface of the mold is a curved surface with a fixed curvature. After the material is cured and formed in the mold, a curved light-transmitting adhesive layer with a recessed center and a fixed curvature is obtained. The curved surface of the light-transmitting adhesive layer consists of two symmetrical spherical parts. The intersection of the two spherical parts is located above the chip and has a certain width, exhibiting a concave shape along the front-to-back axis. The upper surface can also use three or more spherical surfaces converging at the central concave point, as long as it ensures that the light concentrated at the center is refracted evenly to the sides. The specific curvature of the curved surface needs to be determined by comprehensively considering the size of the LED chip and the target light emission angle. The intersection of the two curved surfaces at the lowest position is located above the center point of maximum light intensity of the LED chip, which refracts more of the light concentrated at the center to the sides, changing the original Lambertian light emission mode of the LED chip. The coverage area of ​​the light-transmitting adhesive layer includes the area around the LED chip and the top surface, such as... Figure 1 As shown, the thickness of the light-transmitting adhesive layer 30 extends from the surface of the substrate 10 to above the LED chip 20. In the curved surface of the upper part, the center point at the lowest position is higher than the light-emitting surface 21 of the LED chip. The thickness of the light-transmitting adhesive layer increases the further away from the center and closer to the edge. Furthermore, the side of the light-transmitting adhesive layer is perpendicular to the substrate. If the LED chip is electrically connected to the substrate via wire bonding, the light-transmitting adhesive layer also covers the wire bonding between the LED chip and the substrate. During the fabrication process, the LED chip is first die-bonded to the substrate surface, wire bonding is performed, and then the light-transmitting adhesive layer is prepared by molding or injection molding. Figure 2 and Figure 3 As shown, Figure 2 In the middle, the LED chip 20 has a vertical structure, the electrode of the light-emitting surface 21 is connected to the substrate 10 through the bonding wire 22, and the thickness of the light-transmitting adhesive layer 30 covers the electrode and bonding wire of the LED chip. Figure 3 In the LED chip 20, the positive and negative electrodes are on the surface of the light-emitting surface 21 away from the substrate and are connected to the substrate through bonding wires 22. The thickness of the light-transmitting adhesive layer 30 covers the electrodes of the LED chip and the two bonding wires.

[0012] The reflective layer completely covers the upper surface of the translucent adhesive layer, but not the sides of the translucent adhesive layer. It has a certain degree of reflectivity, used to reflect light directly above the LED chip. This causes the upward-facing light to be refracted through the curved surface, deflecting it outwards. The concave surface in the central area disperses the originally concentrated strong light, while the curved surfaces at the edges guide the light outwards to supplement the illumination. The lower surface of the reflective layer is in contact with the upper surface of the translucent adhesive layer. The upper surface of the reflective layer can be a flat surface, such as... Figure 1 As shown, the upper surface of the reflective layer 40 is a plane; it can also be a curved surface with the same curvature as the upper surface of the light-transmitting adhesive layer, such as... Figure 4 As shown, the reflective layer 40 has the same thickness at all locations, and both the upper and lower surfaces are curved surfaces with the same curvature as the upper surface of the light-transmitting adhesive layer 30. In other embodiments, the upper surface of the reflective layer can also be other irregular rough surfaces, etc., and this embodiment does not limit this.

[0013] The reflective layer is made of silicone or resin containing reflective particles. The material only needs to ensure a certain reflectivity for the LED chip light, allowing it to disperse and concentrate the light at the center. When using silicone or resin containing reflective particles as the reflective layer, the reflective particles can be white inorganic pigments, such as oxides like titanium dioxide, zinc oxide, and zirconium oxide, lead white (lead carbonate), calcium carbonate, and clay minerals like kaolinite, with titanium dioxide being the preferred material.

[0014] This embodiment is an improvement on the previous embodiment. In this embodiment, the light-transmitting adhesive layer can also be doped with a wavelength conversion material to convert the light emitted by the LED chip into another wavelength before emitting it to the outside world, such as converting the blue light emitted by the blue light chip into white light. The wavelength conversion material can be at least one or more of the following: garnet phosphor, oxynitride phosphor, aluminate phosphor, nitride phosphor, sulfide phosphor, KSF phosphor, etc. Different materials can be mixed in the light-transmitting adhesive layer according to different application requirements.

[0015] In another embodiment, the light color of the LED chip is converted by attaching a phosphor layer. The wavelength conversion material inside the phosphor layer converts the transmitted light into another wavelength. This wavelength conversion material is a phosphor that can be excited by the light emitted by the LED chip, thereby obtaining a different specific light color than the light emitted by the LED chip. The wavelength conversion material can be at least one or more of the following: garnet phosphor, oxynitride phosphor, aluminate phosphor, nitride phosphor, sulfide phosphor, KSF phosphor, etc. Depending on the application, different materials can be mixed in the phosphor layer. A colloidal phosphor film can be prepared by mixing silicone or resin with the wavelength conversion material. Especially when applied to high-power applications, such as automotive lights, the light conversion layer can be prepared by mixing glass with the wavelength conversion material to obtain a glass phosphor film (PIG); or it can be prepared by mixing ceramic with the wavelength conversion material to obtain a ceramic phosphor film (PIC). The phosphor layer at least covers the light-emitting surface of the LED chip, and its shape and size are consistent with or slightly larger than the light-emitting surface of the LED chip. Additionally, a white adhesive or a second phosphor layer can be surrounding the side of the LED chip. Figure 5 As shown, a phosphor layer 23 is formed on the light-emitting surface of the LED chip 20, and a white adhesive 24 surrounds the sides of the LED chip and the phosphor layer. A light-transmitting adhesive layer 30 completely covers the LED chip, the phosphor layer, and the white adhesive, and a reflective layer 40 covers the upper surface of the light-transmitting adhesive layer. Another example is... Figure 6 As shown, a phosphor layer 23 is formed on the light-emitting surface of the LED chip 20, and a second phosphor layer 25 is formed on the side of the LED chip. The phosphor layer 23 and the second phosphor layer 25 are formed simultaneously during the preparation process. The light-transmitting adhesive layer 30 completely covers the LED chip, the phosphor layer and the second phosphor layer, and the reflective layer 40 covers the upper surface of the light-transmitting adhesive layer.

[0016] It should be noted that the above embodiments can be freely combined as needed. The above description is only a preferred embodiment of this utility model. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. An LED light-emitting device, characterized in that, include: Substrate and LED chip disposed on substrate; A light-transmitting adhesive layer is wrapped around the LED chip and on its upper surface. The upper surface of the light-transmitting adhesive layer is a concave curved surface with a fixed curvature. The reflective layer covers the upper surface of the light-transmitting adhesive layer.

2. The LED light-emitting device as described in claim 1, characterized in that, The LED chip has a vertical or upright structure, and the light-transmitting adhesive layer covers the chip electrodes and electrode bonding wires.

3. The LED light-emitting device as described in claim 1 or 2, characterized in that, It also includes a wavelength conversion material inside the light-transmitting adhesive layer.

4. The LED light-emitting device as described in claim 1 or 2, characterized in that, It also includes a phosphor layer formed on the light-emitting surface of the LED chip, wherein the phosphor layer contains a wavelength conversion material.

5. The LED light-emitting device as described in claim 4, characterized in that, The side of the LED chip is surrounded by white glue; or, the side of the LED chip is surrounded by a second fluorescent layer.

6. The LED light-emitting device as described in claim 1, 2, or 5, characterized in that, The upper surface of the reflective layer is a flat surface.

7. The LED light-emitting device as described in claim 1, 2, or 5, characterized in that, The upper surface of the reflective layer is a curved surface with the same curvature as the upper surface of the light-transmitting adhesive layer.

8. The LED light-emitting device as described in claim 1, 2, or 5, characterized in that, The reflective layer is a resin material containing reflective particles.

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