Light-emitting device and preparation method thereof

Abstract

The invention provides a light-emitting device and a preparation method thereof. The preparation method comprises the following steps: welding at least two light-emitting diode chips on a circuit board, so that the light-emitting diode chips are electrically connected with the circuit board through a plurality of spaced welding spots; forming a fluorescent layer on one surface, far away from the circuit board, of the light-emitting diode chip; forming a DBR (Distributed Bragg Reflector) layer by adopting an ALD (Atomic Layer Deposition) process, covering the area, except for the welding spots, of one surface, bearing the light-emitting diode chip, of the circuit board by the DBR layer, and covering the side surface of the light-emitting diode chip and the area, except for the welding spots, of one surface, facing the circuit board by the DBR layer, the DBR layer covers the side surface of the fluorescent layer and the surface far away from the light emitting diode chip; and removing the DBR layer on the surface, far away from the light-emitting diode chip, of the fluorescent layer.

Description

Technical Field

[0001] The present disclosure relates to the field of light-emitting devices, and in particular to a light-emitting device and a method for preparing the same. Background Art

[0002] Light emitting diodes (LEDs) have the advantages of energy saving, high brightness, high durability, long life and light weight, and have been widely used in fields such as lighting and display.

[0003] The related art provides a light-emitting device, including: a circuit board, at least two light-emitting diode chips located on the circuit board, and a fluorescent layer covering the light-emitting diode chips.

[0004] However, the light output angle of a single LED chip is 140 to 155 degrees, resulting in a large light-emitting overlap area between adjacent chips, making the axial light intensity insufficient, making it difficult to use the light-emitting device in scenarios such as car lights that require axial light output intensity. Summary of the Invention

[0005] The embodiments of the present disclosure provide a light emitting device and a method for manufacturing the same, which improves the axial light emission of the light emitting device, so that the light emitting device can be used in scenarios such as vehicle lights that require axial light emission intensity. The technical solution is as follows:

[0006] In one aspect, a method for preparing a light-emitting device is provided, the method comprising:

[0007] Soldering at least two light-emitting diode chips to a circuit board so that the light-emitting diode chips are electrically connected to the circuit board through a plurality of spaced solder joints;

[0008] forming a fluorescent layer on a side of the light emitting diode chip away from the circuit board;

[0009] A DBR layer is formed using an ALD process, wherein the DBR layer covers the side of the circuit board that supports the LED chip except for the solder joints, the DBR layer covers the side of the LED chip and the side facing the circuit board except for the solder joints, and the DBR layer covers the side of the phosphor layer and the side away from the LED chip;

[0010] The DBR layer on a side of the phosphor layer away from the light emitting diode chip is removed.

[0011] Optionally, the forming of the DBR layer by adopting the ALD process includes:

[0012] The first sub-layer and the second sub-layer are sequentially formed using the ALD process, and the process is repeated for 30 to 50 cycles;

[0013] The thickness of the first sub-layer is 1 / 4 of the wavelength of the light-emitting diode chip, and the thickness of the second sub-layer is 1 / 4 of the wavelength of the light-emitting diode chip.

[0014] Optionally, the material of the first sub-layer is Al2O3, and the material of the second sub-layer is TiO2.

[0015] Optionally, the sequentially forming the first sub-layer and the second sub-layer by using an ALD process includes:

[0016] In an environment of a temperature of 100 to 250° C., Al(CH 3 ) 3 and H 2 O or Al(CH 3 ) 3 and O 3 are sequentially introduced into the ALD machine to form the first sub-layer;

[0017] In an environment with a temperature of 100-250° C., TiCl 4 and H 2 O are sequentially introduced into the ALD machine to form the second sub-layer.

[0018] Optionally, removing the DBR layer on a side of the fluorescent layer away from the light-emitting diode chip includes:

[0019] adhering the circuit board to a ceramic plate;

[0020] removing the DBR layer on a side of the phosphor layer away from the light-emitting diode chip through grinding and CMP processes;

[0021] After cleaning, the light-emitting device is obtained.

[0022] Optionally, the thickness of the fluorescent layer is 120-180 μm.

[0023] In another aspect, a light emitting device is provided, comprising: at least two light emitting diode chips, a circuit board, a phosphor layer, and a DBR layer;

[0024] The LED chip is electrically connected to the circuit board through a plurality of spaced solder joints. The fluorescent layer is located on the side of the LED chip away from the circuit board. The DBR layer covers the area of ​​the side of the circuit board carrying the LED chip except the solder joints. The DBR layer covers the side surfaces of the LED chip and the area of ​​the side facing the circuit board except the solder joints.

[0025] Optionally, the DBR layer includes a first sublayer and a second sublayer that are repeated periodically, and the number of periods is 30 to 50;

[0026] The thickness of the first sub-layer is 1 / 4 of the wavelength of the light-emitting diode chip, and the thickness of the second sub-layer is 1 / 4 of the wavelength of the light-emitting diode chip.

[0027] Optionally, the material of the first sub-layer is Al2O3, and the material of the second sub-layer is TiO2.

[0028] Optionally, the thickness of the fluorescent layer is 120-180 μm.

[0029] The technical solutions provided by the embodiments of the present disclosure have the following beneficial effects:

[0030] In the disclosed embodiment, after forming a phosphor layer on the LED chip, a DBR layer is formed using an ALD process. This DBR layer covers the PCB, the bottom surface of the LED chip, and the sides of the LED chip. When the LED chip emits light, the light is reflected by the DBRs on the bottom and sides, resulting in a smaller light output angle and a smaller overlap between adjacent chips. This improves axial light intensity, allowing the light-emitting device to be used in applications requiring axial light output, such as automotive lighting. Furthermore, the DBR layer produced using the ALD process provides better coverage of the chip bottom and sides, resulting in a stronger reflective effect, which helps improve the light output angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 This is a flow chart of a method for preparing a light-emitting device provided by an embodiment of the present disclosure;

[0033] Figure 2 This is a flow chart of a method for preparing a light-emitting device provided by an embodiment of the present disclosure;

[0034] Figure 3 is a schematic structural diagram of a light-emitting device provided by an embodiment of the present disclosure during the manufacturing process;

[0035] Figure 4 is a schematic structural diagram of a light-emitting device provided by an embodiment of the present disclosure during the manufacturing process;

[0036] Figure 5 is a schematic structural diagram of a light-emitting device provided by an embodiment of the present disclosure during the manufacturing process;

[0037] Figure 6 is a structural schematic diagram of a light-emitting device provided by an embodiment of the present disclosure;

[0038] Figure 7 is a schematic diagram of the light pattern of a light emitting device provided in the related art;

[0039] Figure 8 Schematic diagram of the light pattern of a light emitting device with a sputtered DBR layer provided in an embodiment of the present disclosure;

[0040] Figure 9 This is a schematic diagram of the light pattern of a light-emitting device in which a DBR layer is formed by ALD according to an embodiment of the present disclosure.

[0041] The reference numerals are as follows:

[0042] 101: LED chip; 102: circuit board; 103: solder joint; 104: phosphor layer; 105: DBR layer. DETAILED DESCRIPTION

[0043] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0044] In related art light-emitting devices, the light emission angle of the LED chip is 140-155°. To improve this angle, the disclosed embodiments first use an electron gun DBR evaporation station to evaporate a DBR layer on the sidewalls of the LED chip. Tests have shown that the light emission angle of the LED chip is 125-140°. Although this angle has been reduced, it still does not meet the required angle.

[0045] Furthermore, the embodiment of the present disclosure improves the DBR layer manufacturing process and adopts the atomic layer deposition (ALD) process to manufacture the DBR layer. After experimental verification, the light emission angle of the light emitting diode chip is 110-125°.

[0046] Figure 1 This is a flow chart of a method for preparing a light emitting device according to an embodiment of the present disclosure. Figure 1 , the method steps include:

[0047] S11. Solder at least two light-emitting diode chips to a circuit board, so that the light-emitting diode chips are electrically connected to the circuit board through a plurality of spaced solder joints.

[0048] The light emitting diode may be a flip-chip light emitting diode chip, that is, the electrode side is soldered to the circuit board, and the substrate side serves as the light emitting surface.

[0049] The circuit board may be a printed circuit board (PCB).

[0050] S12, forming a fluorescent layer on a side of the light emitting diode chip away from the circuit board.

[0051] The fluorescent layer may be a fluorescent plate adhered to the light emitting diode chip.

[0052] In the embodiment of the present disclosure, the colors of the LED chip and the fluorescent layer can be coordinated with each other, for example, they can be coordinated with each other to emit white light as a car light.

[0053] The embodiments of the present disclosure do not limit the specific colors of the LED chip and the fluorescent layer.

[0054] For example, the light emitting diode chip is a blue light emitting diode chip, and accordingly, the fluorescent layer is a mixed layer of yttrium aluminum garnet (YAG) fluorescent powder and silica gel.

[0055] S13, forming a DBR layer by adopting an ALD process.

[0056] Among them, the ALD process is a technology that uses gas-phase chemical processes to deposit thin films. Its characteristic is that it can precisely control the thickness and composition of the film at the nanoscale, thereby ensuring the coverage and reflectivity of the DBR.

[0057] The distributed Bragg reflector (DBR) layer covers the side of the circuit board that carries the light-emitting diode chip except the area of ​​the solder joint, the DBR layer covers the side of the light-emitting diode chip and the side facing the circuit board except the area of ​​the solder joint, and the DBR layer covers the side of the fluorescent layer and the side away from the light-emitting diode chip.

[0058] In other words, the ALD process forms a DBR layer that completely encapsulates the LED chip and phosphor layer. During the manufacturing process, a DBR layer is also formed on the surface of the circuit board. Although the DBR on the circuit board surface does not contribute to the reflective effect, it does not need to be removed.

[0059] S14, removing the DBR layer on a side of the fluorescent layer away from the light-emitting diode chip.

[0060] The DBR layer on the side of the phosphor layer away from the light emitting diode chip will block light emission, so this part of the DBR layer needs to be removed.

[0061] In the disclosed embodiment, after forming a phosphor layer on the LED chip, a DBR layer is formed using an ALD process. This DBR layer covers the PCB, the bottom surface of the LED chip, and the sides of the LED chip. When the LED chip emits light, the light is reflected by the DBRs on the bottom and sides, resulting in a smaller light output angle and a smaller overlap between adjacent chips. This improves axial light intensity, allowing the light-emitting device to be used in applications requiring axial light output, such as automotive lighting. Furthermore, the DBR layer produced using the ALD process provides better coverage of the chip bottom and sides, resulting in a stronger reflective effect, which helps improve the light output angle.

[0062] Figure 2 This is a flow chart of a method for preparing a light emitting device according to an embodiment of the present disclosure. Figure 2 , the method steps include:

[0063] S21. Solder at least two light-emitting diode chips onto a circuit board, so that the light-emitting diode chips are electrically connected to the circuit board through a plurality of spaced solder joints.

[0064] The light emitting diode may be a flip-chip light emitting diode chip, that is, the electrode side is soldered to the circuit board, and the substrate side serves as the light emitting surface.

[0065] The circuit board may be a PCB.

[0066] In the embodiment of the present disclosure, the number of LED chips soldered to the circuit board can be designed as needed. Similarly, the number of solder joints used for soldering each LED chip can also be designed as needed. For example, the two electrodes of the LED chip can be soldered to the PCB through two solder joints respectively.

[0067] Figure 3 Schematic diagram of the structure of the light emitting device provided by the embodiment of the present disclosure during the manufacturing process. Figure 3 , the light emitting diode chip 101 is soldered on the circuit board 102 through the solder joints 103 .

[0068] S22 , forming a fluorescent layer on a side of the light emitting diode chip away from the circuit board.

[0069] The fluorescent layer may be a fluorescent plate adhered to the light emitting diode chip.

[0070] In the embodiment of the present disclosure, the thickness of the fluorescent layer is 120-180 μm.

[0071] Exemplarily, the thickness of the fluorescent layer is 150 μm.

[0072] The fluorescent layer having the above-mentioned thickness can ensure the fluorescent effect and emit light of the desired color, while not being too thick, thereby ensuring that the overall size of the light-emitting device is not too large.

[0073] In the embodiment of the present disclosure, the colors of the LED chip and the fluorescent layer can be coordinated with each other, for example, they can be coordinated with each other to emit white light as a car light.

[0074] The embodiments of the present disclosure do not limit the specific colors of the LED chip and the fluorescent layer.

[0075] Figure 4 Schematic diagram of the structure of the light emitting device provided by the embodiment of the present disclosure during the manufacturing process. Figure 4 A fluorescent layer 104 is formed on a side of the LED chip 101 away from the circuit board 102 .

[0076] S23 , forming a first sub-layer and a second sub-layer in sequence by using an ALD process, and repeating the process for 30 to 50 cycles to obtain a DBR layer.

[0077] Exemplarily, the DBR layer includes 40 periods.

[0078] In this implementation, the DBR layer is formed using the above-mentioned period, which can ensure the reflection effect while avoiding excessive thickness.

[0079] The DBR layer covers the side of the circuit board that carries the light-emitting diode chip except the area of ​​the solder joint, the DBR layer covers the side of the light-emitting diode chip and the side facing the circuit board except the area of ​​the solder joint, and the DBR layer covers the side of the fluorescent layer and the side away from the light-emitting diode chip.

[0080] In other words, the ALD process forms a DBR layer that completely encapsulates the LED chip and phosphor layer. During the manufacturing process, a DBR layer is also formed on the surface of the circuit board. Although the DBR on the circuit board surface does not contribute to the reflective effect, it does not need to be removed.

[0081] The thickness of the first sub-layer is 1 / 4 of the wavelength of the light-emitting diode chip, and the thickness of the second sub-layer is 1 / 4 of the wavelength of the light-emitting diode chip.

[0082] For example, if the wavelength of the light emitting diode chip is 510 nm, then 1 / 4 of the wavelength of the light emitting diode chip is 1 / 4 of 510 nm.

[0083] In this implementation, the total reflection effect of the DBR layer can be achieved by using the first sublayer and the second sublayer with the above thicknesses.

[0084] In the embodiment of the present disclosure, the material of the first sub-layer is Al2O3, and the material of the second sub-layer is TiO2.

[0085] Accordingly, the step of sequentially forming the first sub-layer and the second sub-layer by using the ALD process includes:

[0086] In an environment of a temperature of 100 to 250° C., Al(CH 3 ) 3 and H 2 O or Al(CH 3 ) 3 and O 3 are sequentially introduced into the ALD machine to form the first sub-layer;

[0087] In an environment with a temperature of 100-250° C., TiCl 4 and H 2 O are sequentially introduced into the ALD machine to form the second sub-layer.

[0088] Illustratively, the ambient temperature may be 150 or 200°C.

[0089] In the embodiment of the present disclosure, when Al(CH3)3 and H2O or Al(CH3)3 and O3 are introduced in sequence, the flow rate can be 80-150 sccm (for example, 120 sccm), and the base pressure is 1*10 -3 Pa.

[0090] In the embodiment of the present disclosure, TiCl4 and H2O are introduced sequentially, and the flow rate can be 120-150 sccm (for example, 135 sccm), and the base pressure is 1*10 -3 Pa.

[0091] Figure 5 Schematic diagram of the structure of the light emitting device provided by the embodiment of the present disclosure during the manufacturing process. Figure 5 Through the ALD process, a DBR layer 105 is formed to cover the light-emitting diode chip 101 and the phosphor layer 104 . At the same time, the DBR layer 105 also covers the surface of the circuit board 102 .

[0092] S24, adhering the circuit board to the ceramic plate.

[0093] In one example, the circuit board may be adhered to the ceramic disk by wax.

[0094] S25 , removing the DBR layer on a side of the phosphor layer away from the light emitting diode chip through grinding and CMP processes.

[0095] Among them, chemical mechanical polishing (CMP) is a technology used to flatten the surface of semiconductor wafers by combining chemical etching and mechanical grinding.

[0096] Figure 6Schematic diagram of a light emitting device provided by an embodiment of the present disclosure. Figure 6 After the grinding and CMP processes, the DBR layer 105 covers the area of ​​the side of the circuit board 102 that carries the light-emitting diode chip 101 except the area of ​​the solder joint 103, and the DBR layer 105 covers the side of the light-emitting diode chip 101 and the area of ​​the side facing the circuit board 102 except the area of ​​the solder joint 103.

[0097] S26, after cleaning, the light-emitting device is obtained.

[0098] Cleaning removes residues from the grinding and CMP processes to obtain a clean light-emitting device.

[0099] The present disclosure provides a light emitting device. Figures 1 to 5 The method shown in any one of the figures includes: at least two light emitting diode chips 101 , a circuit board 102 , a phosphor layer 104 and a DBR layer 105 .

[0100] The LED chip 101 is electrically connected to the circuit board 102 via a plurality of spaced solder joints 103. The fluorescent layer 104 is located on the side of the LED chip 101 away from the circuit board 102. The DBR layer 105 covers the area of ​​the side of the circuit board 102 that supports the LED chip 101, excluding the solder joints 103. The DBR layer 105 also covers the side surfaces of the LED chip 101 and the area on the side facing the circuit board 102, excluding the solder joints 103.

[0101] In the embodiment of the present disclosure, after forming a fluorescent layer on the LED chip, a DBR layer is formed through the ALD process. The DBR layer will cover the PCB, the bottom surface of the LED chip, and the side surface of the LED chip. In this way, when the LED chip emits light, the light will be reflected by the DBR on the bottom and side surfaces, making the light output angle smaller, reducing the light-emitting overlapping area between adjacent chips in the side direction, and improving the axial light intensity, so that the light-emitting device can be used in scenes requiring axial light output intensity, such as car lights.

[0102] In the embodiment of the present disclosure, the light emitting diode 101 may be a flip-chip light emitting diode chip, that is, the electrode side is soldered to the circuit board, and the substrate side serves as the light emitting surface.

[0103] In the embodiment of the present disclosure, the circuit board 102 may be a PCB.

[0104] In the embodiment of the present disclosure, the number of LED chips soldered to the circuit board can be designed as needed. Similarly, the number of solder joints used for soldering each LED chip can also be designed as needed. For example, the two electrodes of the LED chip can be soldered to the PCB through two solder joints respectively.

[0105] The fluorescent layer 104 may be a fluorescent plate adhered to the light emitting diode chip.

[0106] In the embodiment of the present disclosure, the thickness of the fluorescent layer 104 is 120-180 μm.

[0107] Exemplarily, the thickness of the fluorescent layer 104 is 150 μm.

[0108] The fluorescent layer having the above-mentioned thickness can ensure the fluorescent effect and emit light of the desired color, while not being too thick, thereby ensuring that the overall size of the light-emitting device is not too large.

[0109] In the embodiment of the present disclosure, the colors of the LED chip and the fluorescent layer can be coordinated with each other, for example, they can be coordinated with each other to emit white light as a car light.

[0110] The embodiments of the present disclosure do not limit the specific colors of the LED chip and the fluorescent layer.

[0111] In the embodiment of the present disclosure, the DBR layer 105 includes a first sub-layer and a second sub-layer that are repeated periodically, with the number of periods being 30 to 50.

[0112] Exemplarily, the DBR layer includes 40 periods.

[0113] In this implementation, the DBR layer is formed using the above-mentioned period, which can ensure the reflection effect while avoiding excessive thickness.

[0114] The thickness of the first sub-layer is 1 / 4 of the wavelength of the light-emitting diode chip, and the thickness of the second sub-layer is 1 / 4 of the wavelength of the light-emitting diode chip.

[0115] In this implementation, the total reflection effect of the DBR layer can be achieved by using the first sublayer and the second sublayer with the above thicknesses.

[0116] In the embodiment of the present disclosure, the material of the first sub-layer is Al2O3, and the material of the second sub-layer is TiO2.

[0117] Table 1 below is a comparison of the light emission angles of the three structures using related technologies, evaporation DBR layer and ALD process to produce DBR layer.

[0118] Table 1

[0119] Craftsmanship Light Angle Light pattern diagram No DBR 140～155° Figure 7 Evaporation DBR 125～140° Figure 8 ALD process to produce DBR 110～125° Figure 9

[0120] exist Figures 7 to 9 In the figure, the horizontal axis is the light intensity. Figure 7 and Figure 8 The unit is mlx, Figure 9 The unit is lx; the vertical axis is the chip test angle, the unit is °.

[0121] exist Figures 7 to 9 , curve A, curve B, and curve C correspond to a test curve with Phi=0 degree, an average test curve, and a test curve with Phi=90 degree, respectively.

[0122] When Phi = 90 degrees, the two test probes and the N and P electrodes of the LED are projected in a straight line. When Phi = 0 degrees, the line connecting the two test probes is perpendicular to the line connecting the N and P electrodes of the LED.

[0123] based on Figures 7 to 9 It can be seen that forming the DBR layer using the ALD process can greatly improve the light output angle of the light-emitting device.

[0124] An embodiment of the present disclosure further provides a display device, which includes the light-emitting unit and a power supply as described above, wherein the light-emitting unit is connected to the power supply.

[0125] The display device may be a car light or other equipment, and the embodiment of the present disclosure does not limit this.

[0126] In the disclosed embodiment, after forming a phosphor layer on the LED chip, a DBR layer is formed using an ALD process. This DBR layer covers the PCB, the bottom surface of the LED chip, and the sides of the LED chip. When the LED chip emits light, the light is reflected by the DBRs on the bottom and sides, resulting in a smaller light output angle and a smaller overlap between adjacent chips. This improves axial light intensity, allowing the light-emitting device to be used in applications requiring axial light output, such as automotive lighting. Furthermore, the DBR layer produced using the ALD process provides better coverage of the chip bottom and sides, resulting in a stronger reflective effect, which helps improve the light output angle.

[0127] The above description is merely an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. A method for preparing a light-emitting device, characterized in that: The method comprises: Soldering at least two light-emitting diode chips (101) onto a circuit board (102), so that the light-emitting diode chips (101) and the circuit board (102) are electrically connected via a plurality of spaced solder joints (103); forming a fluorescent layer (104) on a side of the light-emitting diode chip (101) away from the circuit board (102); A DBR layer (105) is formed by using an ALD process, wherein the DBR layer (105) covers a side of the circuit board (102) carrying the light-emitting diode chip (101) except for the area of ​​the solder joint (103), the DBR layer (105) covers a side of the light-emitting diode chip (101) and an area of ​​the side facing the circuit board (102) except for the area of ​​the solder joint (103), and the DBR layer (105) covers a side of the fluorescent layer (104) and a side away from the light-emitting diode chip (101); The DBR layer (105) on a side of the fluorescent layer (104) away from the light-emitting diode chip (101) is removed.

2. The method for preparing a light-emitting device according to claim 1, wherein: The forming of the DBR layer (105) by adopting the ALD process comprises: The first sub-layer and the second sub-layer are sequentially formed using the ALD process, and the process is repeated for 30 to 50 cycles; The thickness of the first sub-layer is 1 / 4 of the wavelength of the light-emitting diode chip (101), and the thickness of the second sub-layer is 1 / 4 of the wavelength of the light-emitting diode chip (101).

3. The method for preparing a light-emitting device according to claim 2, wherein: The material of the first sub-layer is Al2O3, and the material of the second sub-layer is TiO2.

4. The method for preparing a light-emitting device according to claim 3, wherein: The method of sequentially forming the first sub-layer and the second sub-layer by using the ALD process includes: In an environment of a temperature of 100 to 250° C., Al(CH 3 ) 3 and H 2 O or Al(CH 3 ) 3 and O 3 are sequentially introduced into the ALD machine to form the first sub-layer; In an environment with a temperature of 100-250° C., TiCl 4 and H 2 O are sequentially introduced into the ALD machine to form the second sub-layer.

5. The method for preparing a light-emitting device according to any one of claims 1 to 4, characterized in that: The step of removing the DBR layer (105) on a side of the fluorescent layer (104) away from the light-emitting diode chip (101) comprises: adhering the circuit board (102) to a ceramic plate; removing the DBR layer (105) on a side of the fluorescent layer (104) away from the light-emitting diode chip (101) through grinding and CMP processes; After cleaning, the light-emitting device is obtained.

6. The method for preparing a light-emitting device according to any one of claims 1 to 4, characterized in that: The thickness of the fluorescent layer (104) is 120-180 μm.

7. A light emitting device, characterized in that: The light-emitting device comprises: at least two light-emitting diode chips (101), a circuit board (102), a fluorescent layer (104) and a DBR layer (105); The light-emitting diode chip (101) is electrically connected to the circuit board (102) via a plurality of spaced solder joints (103); the fluorescent layer (104) is located on a side of the light-emitting diode chip (101) away from the circuit board (102); the DBR layer (105) covers an area of ​​a side of the circuit board (102) carrying the light-emitting diode chip (101) except the solder joints (103); and the DBR layer (105) covers a side of the light-emitting diode chip (101) and an area of ​​a side facing the circuit board (102) except the solder joints (103).

8. The light emitting device according to claim 7, characterized in that The DBR layer (105) comprises a first sublayer and a second sublayer that are repeated periodically, with the number of periods being 30 to 50; The thickness of the first sub-layer is 1 / 4 of the wavelength of the light-emitting diode chip, and the thickness of the second sub-layer is 1 / 4 of the wavelength of the light-emitting diode chip.

9. The light emitting device according to claim 8, characterized in that The material of the first sub-layer is Al2O3, and the material of the second sub-layer is TiO2.

10. The light emitting device according to any one of claims 7 to 9, characterized in that: The thickness of the fluorescent layer (104) is 120-180 μm.

Images