Preparation method of fluorescent powder layer for LED packaging and LED packaging structure

Abstract

The invention discloses a preparation method of a fluorescent powder layer for LED packaging and an LED packaging structure. The laminated structure of the first fluorescent glue and the second fluorescent glue in the scheme solves the problems of overlarge product color drift, serious light attenuation and the like in fluoride fluorescent powder application in the current market; the fluoride fluorescent powder has a narrow emission spectrum and can provide light output with high color purity, and the nitride / silicate / alpha-SiAION fluorescent powder has a wide emission spectrum and can make up for the defect of the fluoride fluorescent powder in spectral distribution, so that the overall spectrum is more balanced, and the light emitting performance of LED white light is improved. Through reasonable fluorescent powder ratio and stacked structure design, energy transfer between fluoride fluorescent powder and nitride / silicate / alpha-SiAION fluorescent powder can be more efficient, energy loss is reduced, and therefore the luminous efficiency of LED white light is improved.

Description

Technical Field

[0001] The invention relates to the technical field of luminescent materials, and in particular to a method for preparing a phosphor layer for LED packaging and an LED packaging structure. Background Art

[0002] In recent years, with the rapid development of the LED packaging industry, the LED white light packaging process has become increasingly mature. LED packaging refers to the process of assembling LED chips and other components (such as connecting wires and packaging materials) together to form a complete LED device. The traditional blue light chip excitation YAG+Nitride phosphor packaging LED white light method can no longer meet people's demand for high-efficiency, high-brightness LED white light.

[0003] The traditional production process of using fluoride phosphors in LED white light includes but is not limited to the following steps: blue light chip, die bonding, wire bonding, glue preparation, glue dispensing, long baking, blanking, spectral testing, etc.

[0004] Fluoride phosphors generally have high luminous efficiency and narrow emission spectra, which makes them potential for application in LED lighting. However, the chemical stability of fluoride phosphors is relatively poor and they are easily affected by environmental factors such as humidity and temperature. These factors may cause changes in the crystal structure of the phosphor, thereby affecting its luminous performance. Fluoride phosphors have poor moisture resistance and are prone to deliquescence when exposed to moisture, resulting in a significant decrease in luminous efficiency. In addition, long-term illumination and temperature fluctuations may also cause changes in the internal crystal structure of the phosphor, thereby reducing the luminous efficiency.

[0005] Therefore, in order to solve the problems of excessive product color drift and severe light decay in the current market application of fluoride phosphors, a new solution is urgently needed to overcome the shortcomings of the existing technology. Summary of the invention

[0006] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for preparing a phosphor layer for LED packaging and an LED packaging structure, which can effectively solve the problems existing in the above-mentioned prior art.

[0007] The technical solution of the present invention is:

[0008] According to one aspect of the present invention, the following steps are included:

[0009] S1, mixing fluoride fluorescent powder and transparent resin in proportion to obtain a first fluorescent glue;

[0010] S2, evacuate the prepared first fluorescent glue until no bubbles are visible;

[0011] S3, using a dispensing machine to evenly dispense a certain amount of the first fluorescent glue in the support bowl of the blue light chip, and centrifuging at a medium speed to make it evenly leveled and reach a semi-precipitated state, so that the first fluorescent glue is evenly leveled;

[0012] S4, then quickly heating the first fluorescent glue on the blue light wafer so that the surface of the first fluorescent glue is solidified and formed;

[0013] S5, mixing one or more components of yellow phosphor, green phosphor or orange phosphor in a certain proportion, adding transparent resin and mixing evenly in proportion, then adding one or more combinations of nitride phosphor, silicate phosphor and α-SiAION phosphor and mixing evenly in proportion to obtain a second fluorescent glue;

[0014] S6, evacuate the prepared second fluorescent glue until no bubbles are visible;

[0015] S7, using a glue dispenser to evenly dispense the second fluorescent glue according to a predetermined amount of glue on the surface of the first fluorescent glue that has been formed, and performing segmented centrifugal precipitation so that the second fluorescent glue evenly covers the surface of the first fluorescent glue;

[0016] S8, continuously heating the second fluorescent glue to solidify and crystallize the second fluorescent glue.

[0017] Furthermore, in step S1, the fluoride phosphor is LaF3, NaYF4, BaGdF5 or K2SiF6, and the amount of the fluoride phosphor accounts for 30% to 60% of the total amount of the first fluorescent glue.

[0018] Furthermore, in step S4, the first fluorescent glue is placed in an oven for high-temperature heating, the temperature of the oven is 140-160° C., and the heating time is 5-25 minutes.

[0019] Furthermore, in step S5, yellow phosphor, green phosphor or orange phosphor and transparent resin are uniformly mixed in a ratio of 1:6 to 1:12, and then nitride phosphor is added, wherein the amount of nitride phosphor accounts for 14.1% to 30% of the second fluorescent glue; the excitation wavelength range of the nitride phosphor is between 600 and 615 nm.

[0020] Furthermore, in step S5, yellow phosphor, green phosphor or orange phosphor and transparent resin are evenly mixed in a ratio of 1:6 to 1:12, and then one or more combinations of silicate phosphor, sulfide phosphor and α-SiAION phosphor are added, and the amount of phosphor accounts for 1 to 30% of the total amount of the second fluorescent glue, and the excitation band is between 590 and 630 nm.

[0021] Furthermore, in step S5, yellow phosphor, green phosphor or orange phosphor and transparent resin are uniformly mixed in a ratio of 1:6 to 1:12, and then silicate phosphor is added, and the amount of silicate phosphor accounts for 0.5% to 75% of the total amount of the second fluorescent glue, and the excitation band is between 510 and 620 nm.

[0022] Furthermore, in step S8, the first fluorescent glue and the second fluorescent glue are placed in an oven, and after being heated at a predetermined temperature for a period of time, the temperature of the oven needs to be increased and heated for another period of time.

[0023] Further, in step S8, the temperature of the first oven is 90-110° C., the heating time is 50-70 min, and the temperature of the second oven is 140-160° C., the heating time is 200-280 min.

[0024] Furthermore, in step S1, the transparent resin is one or more combinations of epoxy resin, silicone and nitrile rubber.

[0025] According to another aspect of the present invention, an LED packaging structure includes a bracket, and adopts any one of the preparation methods described above to fill a first fluorescent glue and a second fluorescent glue in layers in sequence in the bracket bowl of the bracket.

[0026] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0027] The stacked structure of the first fluorescent glue and the second fluorescent glue in this solution can solve the problems of excessive product color drift and severe light decay in the application of fluoride fluorescent powders in the current market; fluoride fluorescent powders have a narrow emission spectrum and can provide light output with high color purity, while nitride / silicate / α-SiAION fluorescent powders have a wide emission spectrum, which can make up for the shortcomings of fluoride fluorescent powders in spectral distribution, making the overall spectrum more balanced, thereby improving the luminous performance of LED white light. Through reasonable phosphor ratios and stacked structure design, the energy transfer between fluoride fluorescent powders and nitride / silicate / α-SiAION fluorescent powders can be made more efficient, reducing energy losses, thereby improving the luminous efficiency of LED white light.

[0028] Fluoride phosphors may experience color temperature drift during use, while nitride / silicate / α-SiAION phosphors have better color temperature stability. Through the design of the stacked structure, the two phosphors can compensate each other during the light-emitting process, thereby reducing color temperature drift and maintaining the stability of the color temperature of LED white light. The phosphors in the stacked structure can restrain and balance each other, making the color coordinates of LED white light change more slowly during long-term use, thereby improving the stability of color coordinates; fluoride phosphors are prone to light decay during long-term use, while nitride / silicate / α-SiAION phosphors have relatively small light decay. It can make LED white light more stable during the light-emitting process, reduce the occurrence of light decay, and thus extend the service life of LED. The phosphors in the stacked structure can protect each other, reduce the erosion and damage of the external environment to the phosphors, thereby improving the anti-aging ability of LED white light. The design of the stacked structure can make the phosphors more evenly distributed on the surface of the LED chip during the packaging process, thereby improving the packaging quality and reducing the defective rate during the packaging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a schematic diagram of the preparation steps of the present invention;

[0031] Figure 2 This is a schematic diagram of the three-dimensional structure of the first fluorescent glue, the second fluorescent glue and the bracket in the present invention;

[0032] Figure 3 It is a schematic diagram of the cross-sectional structure of the first fluorescent glue, the second fluorescent glue and the bracket in the present invention;

[0033] In the figure: first fluorescent glue-1, second fluorescent glue-2, and bracket-3. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention. Similarly, the following examples are only partial embodiments of the present invention rather than all embodiments, and all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0035] like Figures 1 to 3As shown, the present invention provides a method for preparing a phosphor layer for LED packaging and an LED packaging structure.

[0036] Embodiment 1:

[0037] See also Figures 1 to 3 , a method for preparing a phosphor layer for LED packaging, comprising the following steps:

[0038] S1, fluoride phosphor and transparent resin are mixed evenly in proportion to obtain the first fluorescent glue; specifically, the fluoride phosphor is LaF3, NaYF4, BaGdF5 or K2SiF6. Of course, in other embodiments, it can also be other types of fluoride phosphors, such as A2XF6:Mn4+(A=Li, Na, K, Rb, Cs, NH4; X=Si, Ge, Sn, Ti, Zr, Hf), BXF6·6H2O:Mn4+(B=Ba, Zn; X=Si, Ge, Sn, Ti), etc. These phosphors can obtain various colors of light through different doping ions and matrix combinations to meet different application requirements. The amount of fluoride phosphor accounts for 30% to 60% of the total amount of the first fluorescent glue. Preferably, the fluoride phosphor accounts for 45% to 50% of the first fluorescent glue. The transparent resin is one or more combinations of epoxy resin, silica gel and nitrile rubber. Preferably, the transparent resin is nitrile rubber. Nitrile rubber contains polar cyanide and has high stability to non-polar or weakly polar oils and organic solvents, which enables it to maintain good stability when mixed with fluorescent powder and glue, and is not easily corroded by oil or other solvents. The wear resistance of nitrile rubber is 30% to 45% higher than that of natural rubber, which enables fluorescent glue to maintain good durability and wear resistance during use.

[0039] S2, evacuate the prepared first fluorescent glue until no bubbles are visible; bubbles in the fluorescent glue will scatter light, resulting in reduced light efficiency of LED white light. Through degassing treatment, the number of bubbles in the fluorescent glue can be significantly reduced, thereby reducing light scattering and improving the light efficiency of LED white light. The presence of bubbles will interfere with the propagation path of light, reducing the brightness of LED white light. After degassing treatment, the bubbles in the fluorescent glue are completely removed, and the light propagation is smoother, thereby improving the brightness of LED white light.

[0040] S3, use a dispensing machine to evenly dispense a certain amount of the first fluorescent glue in the bowl of the blue light chip support, and perform medium-speed centrifugation to make it evenly leveled and reach a semi-precipitated state, so that the first fluorescent glue is evenly leveled; semi-precipitation helps the fluorescent glue to be evenly distributed in the bowl of the support. Through the precise control of the dispensing machine, the fluorescent glue is evenly dispensed in the bowl, and then under the action of semi-precipitation, the fluorescent glue can be naturally leveled, reducing the generation of bubbles and gaps, so that the distribution of the fluorescent powder in the colloid is more uniform.

[0041] S4, then quickly heating the first fluorescent glue on the blue light chip to solidify the surface of the first fluorescent glue; specifically, putting the first fluorescent glue into an oven for high-temperature heating, the temperature of the oven is 140-160°C, and the heating time is 5-25 minutes. Preferably, the temperature of the oven is 150-155°C, and the heating time is 15-20 minutes.

[0042] S5, mix one or more components of yellow phosphor, green phosphor or orange phosphor in a certain proportion. The mixing ratio of yellow phosphor, green phosphor or orange phosphor is a direct application of the prior art, and its proportion is not described here. Then add transparent resin and mix evenly in proportion, then add one or more combinations of nitride phosphor, silicate phosphor, α-SiAION phosphor, mix evenly in proportion, and obtain the second fluorescent glue; specifically, after mixing yellow phosphor, green phosphor or orange phosphor and transparent resin in a ratio of 1:6 to 1:12, then add nitride phosphor, the amount of nitride phosphor accounts for 14.1% to 30% of the second fluorescent glue; the excitation wavelength range of nitride phosphor is between 600 and 615nm.

[0043] S6, evacuate the prepared second fluorescent glue until no bubbles are visible;

[0044] S7, use a glue dispenser to evenly dispense the second fluorescent glue according to a predetermined amount of glue on the surface of the first fluorescent glue that has been formed, and perform segmented centrifugal sedimentation to make the second fluorescent glue evenly cover the surface of the first fluorescent glue; through the sedimentation treatment, the second fluorescent glue can evenly cover the surface of the first fluorescent glue, making the fluorescent powder layer more complete and uniform.

[0045] S8, continuously heat the second fluorescent glue to solidify and crystallize the second fluorescent glue. Specifically, the first fluorescent glue and the second fluorescent glue are placed in an oven, and after being heated for a period of time according to a predetermined temperature, the temperature of the oven needs to be increased and heated again for a period of time. The temperature of the first oven is 90-110°C, and the heating time is 50-70 minutes. The temperature of the second oven is 140-160°C, and the heating time is 200-280 minutes. Preferably, the temperature of the first oven is 100-105°C, and the heating time is 60-65 minutes. The temperature of the second oven is 150-155°C, and the heating time is 240-260 minutes. During the curing process, the second fluorescent glue may produce residual stress. The second heating helps to release these residual stresses, improve the stability of the second fluorescent layer, and ensure that the second fluorescent glue is completely cured to avoid performance degradation caused by incomplete curing, which helps to improve the luminous efficiency and light color consistency of the LED.

[0046] Embodiment 2, a method for preparing a phosphor layer for LED packaging, comprising the following steps:

[0047] S1, fluoride phosphor and transparent resin are mixed evenly in proportion to obtain a first fluorescent glue; specifically, the fluoride phosphor is LaF3, NaYF4, BaGdF5 or K2SiF6, and the fluoride phosphor is mixed evenly with the transparent resin in a ratio of 30% to 60% of the first fluorescent glue. The transparent resin is one or more combinations of epoxy resin, silica gel and nitrile rubber. Preferably, the transparent resin is nitrile rubber.

[0048] S2, evacuate the prepared first fluorescent glue until no bubbles are visible;

[0049] S3, using a dispensing machine to evenly dispense a certain amount of the first fluorescent glue in the support bowl of the blue light chip, and centrifuging at a medium speed to make it evenly leveled and reach a semi-precipitated state, so that the first fluorescent glue is evenly leveled;

[0050] S4, then quickly heating the first fluorescent glue on the blue light chip to solidify the surface of the first fluorescent glue; specifically, putting the first fluorescent glue into an oven for high-temperature heating, the temperature of the oven is 140-160° C., and the heating time is 5-25 minutes.

[0051] S5, mixing one or more components of yellow phosphor, green phosphor or orange phosphor in a certain proportion, adding transparent resin in a proportion of 1:6 to 1:12 and mixing evenly, then adding one or more combinations of silicate phosphor, sulfide phosphor and α-SiAION phosphor, and the amount of phosphor used accounts for 1 to 30% of the total amount of the second fluorescent glue, and the excitation band is between 590 and 630nm.

[0052] S6, evacuate the prepared second fluorescent glue until no bubbles are visible;

[0053] S7, using a glue dispenser to evenly dispense the second fluorescent glue according to a predetermined amount of glue on the surface of the first fluorescent glue that has been formed, and performing segmented centrifugal precipitation so that the second fluorescent glue evenly covers the surface of the first fluorescent glue;

[0054] S8, continuously heat the second fluorescent glue to solidify and crystallize the second fluorescent glue. Specifically, put the first fluorescent glue and the second fluorescent glue into an oven, and after heating them for a period of time according to a predetermined temperature, it is necessary to increase the temperature of the oven and heat them for a period of time. The temperature of the first oven is 90-110°C, and the heating time is 50-70 minutes. The temperature of the second oven is 140-160°C, and the heating time is 200-280 minutes.

[0055] Embodiment 3, a method for preparing a phosphor layer for LED packaging, comprising the following steps:

[0056] S1, fluoride phosphor and transparent resin are mixed evenly in proportion to obtain a first fluorescent glue; specifically, the fluoride phosphor is LaF3, NaYF4, BaGdF5 or K2SiF6, and the fluoride phosphor is mixed evenly with the transparent resin in a ratio of 30% to 60% of the first fluorescent glue. The transparent resin is one or more combinations of epoxy resin, silica gel and nitrile rubber. Preferably, the transparent resin is nitrile rubber.

[0057] S2, evacuate the prepared first fluorescent glue until no bubbles are visible;

[0058] S3, using a dispensing machine to evenly dispense a certain amount of the first fluorescent glue in the support bowl of the blue light chip, and centrifuging at a medium speed to make it evenly leveled and reach a semi-precipitated state, so that the first fluorescent glue is evenly leveled;

[0059] S4, then quickly heating the first fluorescent glue on the blue light chip to solidify the surface of the first fluorescent glue; specifically, putting the first fluorescent glue into an oven for high-temperature heating, the temperature of the oven is 140-160° C., and the heating time is 5-25 minutes.

[0060] S5, mixing one or more components of yellow phosphor, green phosphor or orange phosphor in a certain proportion, adding transparent resin in a proportion of 1:6 to 1:12 and mixing evenly, then adding silicate phosphor, wherein the silicate phosphor accounts for 0.5% to 75% of the second fluorescent glue; the excitation band of the silicate phosphor is between 510 and 620 nm.

[0061] S6, evacuate the prepared second fluorescent glue until no bubbles are visible;

[0062] S7, using a glue dispenser to evenly dispense the second fluorescent glue according to a predetermined amount of glue on the surface of the first fluorescent glue that has been formed, and performing segmented centrifugal precipitation so that the second fluorescent glue evenly covers the surface of the first fluorescent glue;

[0063] S8, continuously heat the second fluorescent glue to solidify and crystallize the second fluorescent glue. Specifically, put the first fluorescent glue and the second fluorescent glue into an oven, and after heating them for a period of time according to a predetermined temperature, it is necessary to increase the temperature of the oven and heat them for a period of time. The temperature of the first oven is 90-110°C, and the heating time is 50-70 minutes. The temperature of the second oven is 140-160°C, and the heating time is 200-280 minutes.

[0064] See also Figure 2 and Figure 3According to another aspect of the present invention, an LED packaging structure includes a bracket 3, and a first fluorescent glue 1 and a second fluorescent glue 2 are filled in layers in sequence in the bracket bowl of the bracket 3 using a preparation method as described in any of the above embodiments.

[0065] Embodiment 1, embodiment 2 and embodiment 3 are all applied to the manufacture of LDE devices, and specifically include the following steps:

[0066] S1, the blue light chip is the core component of the LED white light. The blue light is combined with the light emitted by the phosphor to form white light. The blue light chip is bonded to the LED bracket with a bonding adhesive using an automatic bonding machine;

[0067] S2, clean the LED bracket, remove dust and impurities on the surface, apply a proper amount of bonding glue on the LED bracket, use an automatic bonding machine to accurately place the blue light chip on the LED bracket, and ensure that it forms a good bond with the bonding glue;

[0068] S3, using a metal wire (such as a gold wire) to weld the pad on the blue light chip and the conductive area on the LED bracket;

[0069] S4, using a glue dispensing machine to evenly apply the first fluorescent glue prepared in the above preparation method to the cup-shaped area formed by the LED bracket;

[0070] S5, putting the LED bracket coated with the first fluorescent glue into an oven for curing;

[0071] S6, using a glue dispenser to evenly apply the second fluorescent glue prepared in the above preparation method on the surface on which the first fluorescent glue has been cured;

[0072] S7, putting the LED bracket coated with the second fluorescent glue into an oven for curing;

[0073] S8, taking the cured LED bracket out of the oven and cutting it into independent LED lamp bead units;

[0074] S9, use a spectrometer to test the photoelectric performance of LED lamp beads and classify them according to parameters such as brightness and light color;

[0075] S10, packing the classified LED lamp beads into tapes for subsequent production and use;

[0076] S11, the packaged LED lamp beads are put into storage for management and prepared for sale or subsequent production.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a phosphor layer for LED packaging, characterized in that: The following steps are involved: S1, mixing fluoride fluorescent powder and transparent resin in proportion to obtain a first fluorescent glue; S2, evacuate the prepared first fluorescent glue until no bubbles are visible; S3, using a dispensing machine to evenly dispense a certain amount of the first fluorescent glue in the support bowl of the blue light chip, and centrifuging at a medium speed to make it evenly leveled and reach a semi-precipitated state, so that the first fluorescent glue is evenly leveled; S4, then quickly heating the first fluorescent glue on the blue light wafer so that the surface of the first fluorescent glue is solidified and formed; S5, mixing one or more components of yellow phosphor, green phosphor or orange phosphor in a certain proportion, adding transparent resin and mixing evenly in proportion, then adding one or more combinations of nitride phosphor, silicate phosphor and α-SiAION phosphor and mixing evenly in proportion to obtain a second fluorescent glue; S6, evacuate the prepared second fluorescent glue until no bubbles are visible; S7, using a glue dispenser to evenly dispense the second fluorescent glue according to a predetermined amount of glue on the surface of the first fluorescent glue that has been formed, and performing segmented centrifugal precipitation so that the second fluorescent glue evenly covers the surface of the first fluorescent glue; S8, continuously heating the second fluorescent glue to solidify and crystallize the second fluorescent glue.

2. The method for preparing a phosphor layer for LED packaging according to claim 1, characterized in that: In step S1, the fluoride phosphor is LaF3, NaYF4, BaGdF5 or K2SiF6, and the amount of the fluoride phosphor accounts for 30% to 60% of the total amount of the first phosphor glue.

3. The method for preparing a phosphor layer for LED packaging according to claim 1, characterized in that: In step S4, the first fluorescent glue is placed in an oven for high-temperature heating, the temperature of the oven is 140-160° C., and the heating time is 5-25 minutes.

4. The method for preparing a phosphor layer for LED packaging according to claim 1, characterized in that: In step S5, yellow phosphor, green phosphor or orange phosphor and transparent resin are mixed evenly in a ratio of 1:6 to 1:12, and then nitride phosphor is added. The amount of nitride phosphor accounts for 14.1% to 30% of the second fluorescent glue; the excitation wavelength range of nitride phosphor is between 600 and 615 nm.

5. The method for preparing a phosphor layer for LED packaging according to claim 1, characterized in that: In step S5, yellow phosphor, green phosphor or orange phosphor and transparent resin are evenly mixed in a ratio of 1:6 to 1:12, and then one or more combinations of silicate phosphor, sulfide phosphor and α-SiAION phosphor are added, and the amount of phosphor used accounts for 1 to 30% of the total amount of the second fluorescent glue, and the excitation band is between 590 and 630 nm.

6. The method for preparing a phosphor layer for LED packaging according to claim 1, characterized in that: In step S5, yellow phosphor, green phosphor or orange phosphor and transparent resin are mixed evenly in a ratio of 1:6 to 1:12, and then silicate phosphor is added, and the amount of silicate phosphor accounts for 0.5% to 75% of the total amount of the second fluorescent glue, and the excitation band is between 510 and 620 nm.

7. The method for preparing a phosphor layer for LED packaging according to claim 1, characterized in that: In step S8, the first fluorescent glue and the second fluorescent glue are placed in an oven, and after being heated at a predetermined temperature for a period of time, the temperature of the oven needs to be increased and heated for another period of time.

8. The method for preparing a phosphor layer for LED packaging according to claim 7, characterized in that: In step S8, the temperature of the first oven is 90-110° C., and the heating time is 50-70 minutes. The temperature of the second oven is 140-160° C., and the heating time is 200-280 minutes.

9. The method for preparing a phosphor layer for LED packaging according to claim 1, characterized in that: In step S1 , the transparent resin is one or more combinations of epoxy resin, silicone and nitrile rubber.

10. An LED packaging structure, comprising a bracket (3), characterized in that: By adopting the preparation method as described in any one of claims 1 to 9, the first fluorescent glue (1) and the second fluorescent glue (2) are sequentially filled in layers in the bracket bowl of the bracket (3).

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