COB light-emitting device and manufacturing method of COB light-emitting device

Abstract

The embodiment of the invention provides a COB light-emitting device and a manufacturing method of the COB light-emitting device. The COB light-emitting device is characterized in that the COB light-emitting device comprises a substrate which is provided with a die bonding area; the plurality of light-emitting chips are arranged in the die bonding area of the substrate; the first fluorescent glue layer covers the upper surface of the light-emitting chip and covers the whole die bonding area, and the first fluorescent glue layer comprises first fluorescent powder; and the second fluorescent glue layer covers the first fluorescent glue layer, and the second fluorescent glue layer comprises second fluorescent powder different from the first fluorescent powder. According to the COB light-emitting device provided by the embodiment of the invention, the first fluorescent glue layer covers the upper surface of the light-emitting chip and covers the die bonding area, so that the first fluorescent powder is closer to the light-emitting chip, the excitation efficiency of the first fluorescent powder can be improved, and the heat dissipation efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of lighting technology, and more particularly to a COB light-emitting device and a method for manufacturing a COB light-emitting device. Background Technology

[0002] Currently, LED products packaged with fluoride phosphors (such as KSF and KGF) are becoming increasingly popular, mainly because fluoride phosphors have a significantly higher spectral efficiency than traditional red phosphors such as nitrides.

[0003] However, fluoride phosphors have relatively low excitation efficiency under blue light, and the packaging of white LED products typically includes various phosphors with different structures (e.g., garnet, silicate, silane, nitride, fluoride, etc.). These phosphors have varying densities. Using traditional mixing, dispensing, and deposition processes, the phosphors mix together and settle simultaneously. The heavier phosphors tend to settle to the bottom layer, closer to the chip's light-emitting surface. Ultimately, the proportion of fluoride phosphor near the chip's light-emitting surface is less than that further away. This further affects the excitation and conversion efficiency of the fluoride phosphor, thus impacting the light extraction efficiency of the white LED product. Summary of the Invention

[0004] Therefore, in order to overcome at least some of the defects and deficiencies in the prior art, embodiments of the present invention provide a COB light-emitting device and a method for manufacturing a COB light-emitting device.

[0005] Specifically, in one aspect, the COB light-emitting device provided in the embodiments of the present invention includes: a substrate having a die-bonding region thereon; a plurality of light-emitting chips disposed in the die-bonding region of the substrate; a first phosphor layer covering the upper surface of the light-emitting chips and covering the entire die-bonding region, the first phosphor layer including a first phosphor; and a second phosphor layer covering the first phosphor layer, the second phosphor layer including a second phosphor different from the first phosphor.

[0006] On the other hand, embodiments of the present invention also provide a method for manufacturing a COB light-emitting device, comprising: disposing a plurality of light-emitting chips on a die-bonding region of a substrate; applying a first phosphor mixture comprising a first phosphor, silicone and a diluent to the upper surface of the plurality of light-emitting chips by a powder spraying process or a dispensing process, and covering the entire die-bonding region, wherein the diluent evaporates to form a first phosphor layer; and forming a second phosphor layer on the first phosphor layer, wherein the second phosphor layer comprises a second phosphor, the second phosphor being different from the first phosphor.

[0007] As can be seen from the above, the light-emitting device provided in the embodiments of the present invention covers the upper surface of the light-emitting chip with a first phosphor layer, and a second phosphor layer covers the first phosphor layer. The first phosphor layer includes a first phosphor, thereby bringing the first phosphor closer to the light-emitting chip, which can improve the excitation efficiency of the first phosphor and improve the heat dissipation efficiency. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a schematic flowchart illustrating a method for manufacturing a light-emitting device according to an embodiment of the present invention.

[0010] Figure 2 This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of the present invention.

[0011] Figure 3 This is a schematic diagram of another light-emitting device provided in an embodiment of the present invention.

[0012] Figure 4 This is a schematic diagram of the structure of another light-emitting device provided in an embodiment of the present invention.

[0013] Figure 5 This is a schematic diagram of another light-emitting device provided in an embodiment of the present invention.

[0014] Figure 6 This is a schematic diagram of another light-emitting device provided in an embodiment of the present invention.

[0015] Figure 7 This is a schematic diagram of another light-emitting device provided in an embodiment of the present invention.

[0016] Key component designations: 10. Light-emitting device; 11. Main light-emitting area; 12. Peripheral area; 100. Substrate; 200. Light-emitting chip; 300. First phosphor layer; 400. Second phosphor layer; 410. Deposition layer; 420. Clearing layer. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments described in the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0018] It should be noted that all directional indicators (such as up, down, left, right, front, back, top, bottom) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0019] In the embodiments of this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0020] See Figure 1 and Figure 2 This invention provides a light-emitting device 10 and a method for manufacturing the light-emitting device. Figure 2 The light-emitting device 10 shown can, for example, be transmitted through... Figure 1 The light-emitting device shown is manufactured using the manufacturing method described.

[0021] like Figure 1 As shown, the manufacturing method of the light-emitting device 10 may include, for example, the following steps: S10, The light-emitting chip is placed on the substrate; S20, a first fluorescent adhesive layer is formed on the upper surface of the light-emitting chip by a powder spraying process or a dispensing process, wherein the first fluorescent adhesive mixture includes fluoride phosphor, silica gel and diluent; S30, a second fluorescent adhesive layer is formed on the first fluorescent adhesive layer.

[0022] Specifically, a substrate 100 is provided, and the upper surface of the substrate 100 may include, for example, a die-bonding region to which the light-emitting chip 200 is fixed. In this embodiment, the light-emitting device 10 may be an SMD package (Surface Mount Device), a COB package (Chips on Board), or a filament package. The light-emitting chip 200 may be, for example, one or more. Among the light-emitting devices 10 such as COB packages and filament packages that simultaneously have multiple (usually more than three) light-emitting chips 200 on a substrate 100, the manufacturing method of this embodiment has a significant advantage. A first phosphor layer 300 is formed on the upper surface (i.e. the main light-emitting surface) of the light-emitting chip 200. For example, fluoride phosphor, silicone and diluent are mixed to form a first phosphor mixture. The diluent can be, for example, siloxane or toluene. Then the first phosphor mixture is coated on the upper surface of the light-emitting chip 200 by a powder spraying process or a dispensing process. Since the diluent has volatile properties, after it evaporates, a first phosphor layer 300 including fluoride phosphor and silicone is formed on the upper surface of the light-emitting chip.

[0023] By adding a diluent to the mixture of fluoride phosphor and silicone, the viscosity of the first phosphor mixture can be reduced. This ensures that the first phosphor mixture can be formed more quickly and uniformly on the main light-emitting surface of the light-emitting chip 200 via a powder spraying process, or uniformly on the main light-emitting surface of the light-emitting chip 200 via a rapid dispensing and leveling method. This reduces the amount of silicone used, and the fluoride phosphor is uniformly distributed within the silicone, thereby improving the excitation and conversion effect of the fluoride phosphor and increasing the light extraction efficiency of the light-emitting device 10. In this embodiment, the first phosphor layer 300 can be formed only on the main light-emitting surface (i.e., the upper surface) of the light-emitting chip 200, or it can be simultaneously formed on the substrate 100 surrounding the light-emitting chip 200 and / or covering the side surfaces of the light-emitting chip 200. Specific implementation methods will be described later with different embodiments.

[0024] The second fluorescent adhesive layer 400 is formed on the first fluorescent adhesive layer 300, for example, by a method similar to that used to form the first fluorescent adhesive layer 300, or for example, by a conventional dispensing process. Specifically, in one embodiment of this example, a second fluorescent adhesive mixture can be formed by first mixing yellow-green phosphor with other phosphors such as nitride red phosphor, silica gel, and a diluent, and then applying the second fluorescent adhesive mixture onto the first fluorescent adhesive layer 300 using a powder spraying or dispensing process, allowing the diluent to evaporate before forming the second fluorescent adhesive layer 400. In another embodiment of this example, a third fluorescent adhesive mixture can be formed by first mixing yellow-green phosphor with other phosphors such as nitride red phosphor and silica gel, and then applying the third fluorescent adhesive mixture onto the first fluorescent adhesive layer 300 using a conventional dispensing process to form the second fluorescent adhesive layer 400. Of course, this embodiment is not limited to these methods.

[0025] like Figure 2 As shown, the light-emitting device 10 provided in this embodiment of the invention may include, for example, a substrate 100, a light-emitting chip 200, a first phosphor layer 300, and a second phosphor layer 400. The substrate 100 may be, for example, a metal substrate, a ceramic substrate, a glass substrate, a composite substrate, etc. The light-emitting chip 200 may be, for example, a blue light-emitting chip, and the light-emitting chip 200 is disposed on the substrate 100. The first phosphor layer 300 covers the light-emitting chip 200 and includes fluoride phosphor and silicone, with the fluoride phosphor uniformly distributed within the silicone. The fluoride phosphor is a manganese-activated fluoride series red phosphor; commonly used fluoride phosphors include K2SiF6:Mn. 4+ (KSF), K2TiF6:Mn 4+ (KTF), K2GeF6:Mn 4+ (KGF), etc. A second fluorescent adhesive layer 400 covers the first fluorescent adhesive layer 300. The second fluorescent adhesive layer 400 may include, for example, yellow-green phosphors and nitride red phosphors, or other phosphors, which are not particularly limited in this invention. The light-emitting device 10 provided in this embodiment covers the light-emitting chip 200 with a first fluorescent adhesive layer 300, and a second fluorescent adhesive layer 400 covers the first fluorescent adhesive layer 300. The first fluorescent adhesive layer 300 includes fluoride phosphors and silicone. By sequentially layering the first fluorescent adhesive layer 300 containing fluoride phosphors and the second fluorescent adhesive layer 400 containing other phosphors onto the light-emitting chip 200, the fluoride phosphors, which have relatively low excitation efficiency, are brought closer to the light-emitting chip 200, and particularly closer to the main light-emitting surface of the light-emitting chip 200, thus improving the excitation effect of the fluoride phosphors and further improving the light extraction efficiency of the light-emitting device 10.

[0026] Preferably, the first fluorescent adhesive layer 300 of the present invention is as follows: Figure 1The method shown involves mixing fluoride phosphor with silica gel and a diluent, then forming the mixture onto the light-emitting chip 200 using methods such as powder spraying or dispensing. The first phosphor layer 300 formed in this way, after the diluent evaporates, exhibits specific structural characteristics. This allows the first phosphor layer 300 to more easily and uniformly cover the main light-emitting surface of the light-emitting chip 200, achieving better excitation-conversion effects and light extraction efficiency with less phosphor. Specifically, as... Figure 2 As shown, the space above and on the upper surface of the light-emitting chip 200 is defined as the main light-emitting region 11, and the region outside the main light-emitting region 11 is defined as the peripheral region 12. The first phosphor layer 300 covers the main light-emitting region 11 and the peripheral region 12. In some embodiments of this example, the first phosphor layer 300 may, for example, cover the upper surface and side surface of the light-emitting chip 200, and also cover the upper surface of the substrate 100. In some embodiments, using the upper surface of the substrate 100 as a reference plane, the height H1 of the first phosphor layer 300 on the upper surface of the main light-emitting region 11 is greater than the height H2 of the first phosphor layer 300 on the upper surface of the peripheral region 12. That is, the height H1 between the upper surface of the first phosphor layer 300 on the main light-emitting region 11 and the upper surface of the substrate 100 is greater than the height H2 between the upper surface of the first phosphor layer 300 on the peripheral region 12 and the upper surface of the substrate 100. In other words, the first phosphor layer 300 will exhibit a height difference on its upper surface in a cross-sectional view of the light-emitting device 10 perpendicular to the upper surface of the light-emitting chip 200. In some more preferred embodiments, the height H2 of the first phosphor layer 300 on the upper surface of the peripheral region 12 is even lower than the height H3 of the upper surface of the light-emitting chip 200. That is, the height of the upper surface of the first phosphor layer 300 on the peripheral region 12 relative to the upper surface of the substrate 100 is lower than the height of the upper surface of the light-emitting chip 200 relative to the upper surface of the substrate 100. From another perspective, in this embodiment, the second fluorescent adhesive layer 400 is formed on the first fluorescent adhesive layer 300 and is also formed simultaneously in the main light-emitting region 11 and the peripheral region 12. The height of the second fluorescent adhesive layer 400 on the lower surface of the peripheral region 12 is lower than its height on the lower surface of the main light-emitting region 11. In some more preferred embodiments, the height of the second fluorescent adhesive layer 400 on the lower surface of the peripheral region 12 is even lower than the height H3 of the upper surface of the light-emitting chip 200.

[0027] In embodiments of the present invention, the packaging form of the light-emitting device 10 is, for example, COB packaging (Chips on Board), SMD packaging (Surface Mount Devices), or filament packaging. However, it is particularly worth mentioning that for light-emitting devices 10 with COB packaging or other multi-chip (three or more) packaging (i.e., with a large packaging area), the first phosphor layer 300 formed by mixing fluoride phosphor, silicone, and diluent and then applying it to the light-emitting chip 200 by powder spraying or dispensing overcomes the problem that traditional layered dispensing processes are difficult to implement in large packaging areas. This achieves the effect of more conveniently and uniformly covering the main light-emitting surface of the light-emitting chip 200 with fluoride phosphor, improving the light emission efficiency and uniformity of such products.

[0028] Furthermore, in the first phosphor layer 300 of the light-emitting device 10 provided in some embodiments of the present invention, the fluoride phosphor is uniformly distributed and does not separate into layers. Moreover, its mass percentage (i.e., the ratio of the mass of the fluoride phosphor to the total mass of the fluoride phosphor and the silica gel in the first phosphor layer 300) can be greater than 60%, or even greater than 70%. In traditional dispensing methods, once the mass percentage of the fluoride phosphor exceeds 50%, there is a problem of poor flowability and difficulty in uniform dispensing. Thus, the present invention can reduce the amount of fluoride phosphor used while achieving high excitation conversion effect and high light extraction efficiency. This setting can, for example, avoid affecting the heat dissipation of the light-emitting device 10 when the silica gel content in the first phosphor layer 300 is high. However, it should be noted that the mass percentage of the fluoride phosphor in the first phosphor layer 300 of the light-emitting device 10 of the present invention can be greater than 60%, but this is not intended to limit the mass percentage to greater than 60% in all embodiments. The specific selection will be adjusted according to the light extraction requirements of the light-emitting device 10 and the other phosphors used.

[0029] In embodiments of the present invention, the ratio of fluoride phosphor to silica gel in the first fluorescent adhesive layer 300 can be, for example, between 1:9 and 9:1, that is, the mass percentage of fluoride phosphor in the first fluorescent adhesive layer 300 is between 10% and 90%. Preferably, the mass percentage of fluoride phosphor in the first fluorescent adhesive layer 300 is between 60% and 90%. This setting can, for example, avoid affecting heat dissipation when the silica gel content in the first fluorescent adhesive layer 300 is high. In some embodiments of the present invention, such as... Figure 3 As shown, when the amount of the first fluorescent adhesive layer 300 is large, or the ratio of fluoride phosphor to silica gel is low, the upper surface of the first fluorescent adhesive layer 300 will exhibit a relatively smooth curved surface with a small height difference; for example... Figure 2As shown, when the amount of the first fluorescent adhesive layer 300 is small, or when the ratio of fluoride phosphor to silica gel is high, the upper surface of the first fluorescent adhesive layer 300 may exhibit a greater height difference; for example... Figure 4 As shown, when the amount of the first fluorescent adhesive layer 300 is small, or when the ratio of fluoride phosphor to silica gel is high, the upper surface of the first fluorescent adhesive layer 300 may even be discontinuous, resulting in a non-discontinuous upper surface. The above-mentioned different structures of the first fluorescent adhesive layer 300 are all specific structural features exhibited by the first fluorescent adhesive layer 300 formed by the manufacturing method of the light-emitting device 10 provided in this embodiment of the invention, and are applicable to the corresponding different embodiments below.

[0030] Please see Figure 5 , Figure 5 This is another embodiment of the present invention. The selection and arrangement of the substrate 100, the light-emitting chip 200, and the first phosphor layer 300 in the light-emitting device 10 provided in this embodiment are all consistent with the present invention. Figure 2 The embodiments shown are the same, and will not be repeated here. This embodiment is the same as... Figure 2 The main difference in the illustrated embodiment is that the second phosphor layer 400 provided in this embodiment is disposed on the first phosphor layer 300 in a layered manner. In terms of the preparation method, in addition to the aforementioned method for forming the second phosphor layer 400, steps of natural precipitation and centrifugal / semi-centrifugal precipitation can be added. This allows most of the other phosphors in the second phosphor layer 400 to deposit onto the surface of the first phosphor layer 300, thus giving the second phosphor layer 400 a layered structure. Specifically, the second phosphor layer 400 may include, for example, a deposited layer 410 close to the first phosphor layer 300 and a clearing layer 420 located away from the first phosphor layer 300 from the deposited layer 410. That is, the clearing layer 420 is located on the side of the deposited layer 410 away from the first phosphor layer 300 and away from the light-emitting chip 200. It should be noted that the clearing layer 420 is not completely free of phosphor; it simply means that the content / concentration of phosphors visible to the naked eye in the clearing layer 420 is lower than that in the deposited layer 410.

[0031] In another sense, in a cross-sectional view of the light-emitting device 10 in this embodiment perpendicular to the main light-emitting surface of the light-emitting chip 200, the fluorescent adhesive can be shown as a three-layer structure, including a first fluorescent adhesive layer 300, a deposit layer 410 and a clear adhesive layer 420. The deposit layer 410 is located between the first fluorescent adhesive layer 300 and the clear adhesive layer 420, and the clear adhesive layer 420 is located on the side of the deposit layer 410 away from the light-emitting chip 200. The second fluorescent adhesive layer 400 is formed on the first fluorescent adhesive layer 300 and is also formed simultaneously in the main light-emitting region 11 and the peripheral region 12. The height of the lower surface of the second fluorescent adhesive layer 400 in the peripheral region 12 is lower than the height of its lower surface in the main light-emitting region 11. That is, the height between the lower surface of the second fluorescent adhesive layer 400 in the peripheral region 12 and the upper surface of the substrate 100 is less than the height between the lower surface of the second fluorescent adhesive layer 400 in the main light-emitting region 11 and the upper surface of the substrate 100. This allows the phosphor in the second fluorescent adhesive layer 400 to be more concentrated and close to the substrate 100, which helps to conduct the heat of the phosphor in the second fluorescent adhesive layer 400 downward through the substrate 100 and improves the thermal stability of the light-emitting device 10. In some embodiments of this example, in order to ensure better heat dissipation, a deposition step is added when forming the second phosphor layer 400, so that the second phosphor layer 400 is better leveled, and the phosphor contained therein tends to be deposited towards the substrate 100, and fills the height difference between the first phosphor layer 300 in the main light-emitting region 11 and the peripheral region 12, so that the interface between the first phosphor layer 300 and the deposition layer 410 has a relatively larger height difference, while the interface between the deposition layer 410 and the clear adhesive layer 420 has a smaller height difference; from another perspective, the thickness W3 of the deposition layer 410 of the second phosphor layer 400 in the peripheral region 12 is greater than the thickness W2 of the deposition layer 410 in the main light-emitting region 11. For the CRI90 series light-emitting device 10, to ensure the light emission effect (color, color rendering index, etc.), it is necessary to adjust the appropriate ratio of fluoride phosphor to other phosphors. Furthermore, for better thermal stability (e.g., improved heat dissipation), the amount of the first phosphor layer 300 needs to be controlled. Current experiments have shown that when the ratio of the thickness W1 of the first phosphor layer 300 in the main light-emitting region 11 to the thickness W2 of the deposited layer 410 is less than 2, the aforementioned better effect can be uniformly achieved. Preferably, the thickness W1 of the first phosphor layer 300 in the main light-emitting region 11 is less than the thickness W2 of the deposited layer 410.

[0032] Please refer to Figure 6 , Figure 6 This is another embodiment of the present invention. In this embodiment, the selection and arrangement of the substrate 100, the light-emitting chip 200, and the second phosphor layer 400 in the light-emitting device 10 are the same as those in the present invention. Figure 2 The embodiments shown are the same, and will not be described again here. The light-emitting device 10 in this embodiment is the same as... Figure 2The main difference of the light-emitting device 10 shown is that the first phosphor layer 300 only covers the main light-emitting area 11 and is not disposed in the peripheral area 12. Therefore, when the second phosphor layer 400 is formed on the first phosphor layer 300, it will be located on the side of the main light-emitting area 11 away from the light-emitting chip 200, while it will be directly located on the substrate 100 in the peripheral area 12. However, in this case, it is also consistent that the height H1 of the upper surface of the first phosphor layer 300 in the main light-emitting area 11 is greater than the height H2 of the upper surface of the first phosphor layer 300 in the peripheral area 12 (in this embodiment, this thickness is equal to 0); or more accurately, it is also consistent that the height of the lower surface of the second phosphor layer 400 in the peripheral area 12 is lower than its height of the lower surface in the main light-emitting area 11.

[0033] Refer to Figure 7 , Figure 7 This is another embodiment of the present invention. In this embodiment, the selection and arrangement of the substrate 100, the light-emitting chip 200, and the first phosphor layer 300 in the light-emitting device 10 are the same as those in the present invention. Figure 6 The embodiments shown are the same, and will not be described again here. The light-emitting device 10 in this embodiment is the same as... Figure 6 The main difference between the light-emitting device 10 shown is that, in this embodiment, the second phosphor layer 400 is disposed on the first phosphor layer 300 in a layered manner. Methodically, based on the aforementioned method for forming the second phosphor layer 400, steps of natural precipitation and centrifugal / semi-centrifugal precipitation can be added. This allows most of the other phosphors in the second phosphor layer 400 to deposit onto the surface of the first phosphor layer 300 and the surface of the substrate 100, thus giving the second phosphor layer 400 a layered structure. Specifically, the second phosphor layer 400 may, for example, include a deposited layer 410 and a clearing layer 420 located on the deposited layer 410. The second phosphor layer 400 of this embodiment is different from... Figure 5 The main difference in the second phosphor layer 400 provided in the illustrated embodiment is that the deposited layer 410 in the peripheral region 12 is disposed on the substrate 100. However, the lower surface height of the second phosphor layer 400 in the peripheral region 12 is lower than its lower surface height in the main light-emitting region 11. The thickness W3 of the deposited layer 410 in the peripheral region 12 is greater than the thickness W2 of the deposited layer 410 in the main light-emitting region 11. This allows the phosphor in the second phosphor layer 400 to be more concentrated and close to the substrate 100, which helps to conduct the heat of the phosphor in the second phosphor layer 400 downward through the substrate 100 and improves the thermal stability of the light-emitting device 10.

[0034] Furthermore, it is understood that the foregoing embodiments are merely illustrative examples of the present invention. Provided that the technical features do not conflict, the structure is not contradictory, and the purpose of the invention is not violated, the technical solutions of the various embodiments can be arbitrarily combined and used.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A COB light emitting device, characterized by, The application relates to a light-emitting device, comprising: a substrate provided with a die bonding area; a plurality of light-emitting chips arranged in the die bonding area of the substrate; a first fluorescent glue layer covering the upper surfaces of the light-emitting chips and covering the whole die bonding area, the first fluorescent glue layer comprising first fluorescent powder; a second fluorescent glue layer covering the first fluorescent glue layer, the second fluorescent glue layer comprising second fluorescent powder different from the first fluorescent powder.

2. The COB light emitting device of claim 1, wherein, The first fluorescent glue layer has a continuous uneven upper surface or a discontinuous upper surface.

3. The COB light emitting device of claim 1, wherein the first and second COB substrates are made of a material selected from the group consisting of silicon, sapphire, and gallium arsenide. The light-emitting device comprises a main light-emitting area and a peripheral area, the main light-emitting area being the space above the upper surfaces of the light-emitting chips, and the peripheral area being the area outside the main light-emitting area; the height of the upper surface of the first fluorescent glue layer in the main light-emitting area is greater than the height of the upper surface of the first fluorescent glue layer in the peripheral area.

4. The COB light emitting device of claim 3, wherein the first and second electrodes are formed on the same surface of the substrate. The second fluorescent glue layer comprises a sedimentation layer and a glue removal layer, the sedimentation layer covering the first fluorescent glue layer, and the glue removal layer being located on the side of the sedimentation layer away from the substrate.

5. The COB light emitting device of claim 4, wherein the first and second electrodes are formed on the same surface of the substrate. The thickness of the first fluorescent glue layer is less than the thickness of the sedimentation layer.

6. The COB light emitting device of claim 5, wherein, The sedimentation layer has an uneven upper surface.

7. The COB light emitting device of claim 1, wherein, The first fluorescent powder is fluoride fluorescent powder, and the mass of the fluoride fluorescent powder accounts for 60% or more of the mass of the first fluorescent glue layer.

8. A method of manufacturing a COB light emitting device, characterized by, The application relates to a light-emitting device, comprising: arranging a plurality of light-emitting chips on a die bonding area of a substrate; arranging a first fluorescent glue mixture comprising first fluorescent powder, silica gel and a diluent on the upper surfaces of the light-emitting chips by a powder spraying process or a dispensing process, the diluent forming a first fluorescent glue layer after volatilization; forming a second fluorescent glue layer on the first fluorescent glue layer, the second fluorescent layer comprising second fluorescent powder different from the first fluorescent powder.

9. The method of manufacturing a COB light emitting device according to claim 8, wherein The method for forming the second fluorescent glue layer on the first fluorescent glue layer comprises: arranging a second fluorescent glue mixture comprising the second fluorescent powder and silica gel on the first fluorescent glue layer by a dispensing process; sedimenting most of the second fluorescent powder in the second fluorescent glue layer to form a sedimentation layer and a glue removal layer by a sedimentation process.

10. The method of manufacturing a COB light emitting device according to claim 8, wherein The first fluorescent powder is fluoride fluorescent powder, and the mass of the fluoride fluorescent powder accounts for 60% or more of the mass of the first fluorescent glue layer.

Images