A coating for preventing sulfurization of LED lamp beads and a coating process

Abstract

The application discloses a coating for preventing sulfurization of an LED lamp bead and a coating process, and relates to the technical field of LED lamp beads. The coating for preventing sulfurization of the LED lamp bead comprises coating I and coating II; the coating II is encapsulating glue; the coating I is one of a top coating layer and a bottom coating layer; the top coating layer comprises a sulfur-proof layer; the sulfur-proof layer coating comprises 30-50 parts of polyurethane modified silicon resin, 2-4 parts of dimethyl phthalate, 1-2 parts of calcium carbonate, 1-3 parts of titanium oxide, 10-16 parts of glass fiber, 1-3 parts of an antioxidant, and 1-2 parts of an adhesion enhancer; the top coating layer further comprises a top coating transition layer; the top coating transition layer is phenyl vinyl silicon resin; the bottom coating layer comprises a sulfur-proof layer and a bottom coating adhesion layer; the bottom coating adhesion layer is epoxy group modified silicon resin. The coating process for preventing sulfurization of the LED lamp bead provided by the application comprises die bonding, wire bonding and coating processes, and the obtained LED lamp bead not only has strong sulfurization prevention performance, but also has good weather resistance.

Description

Technical Field

[0001] This application relates to the field of LED lamp bead technology, and in particular to a coating and coating process for an anti-sulfurization LED lamp bead. Background Technology

[0002] The silver plating on the LED chip holder will form silver sulfide upon contact with sulfur-containing gases, and photosensitive silver halide upon contact with acidic chlorine or bromine gases. Both of these reactions can cause the LED light source to fail. Symptoms of sulfidation in LEDs include: blackening of the holder's functional area, decreased luminous flux, and color temperature drift. Since the conductivity of silver sulfide increases with temperature, sulfidated LEDs may also experience leakage during use. As the sulfidation of the silver layer in the holder worsens, the gold wire solder joints mainly adhere to the surface of the silver plating. When the silver layer in the functional area of ​​the holder is completely sulfided, the gold balls will detach, ultimately causing the LED to fail completely, resulting in a dead LED.

[0003] To improve the anti-sulfurization performance of LED chips, encapsulation adhesive technology is commonly used in the market to encapsulate LED chips and extend their service life. However, under thermal expansion and contraction, the bonding wires inside the LED chips are easily broken, leading to functional failure. Even with encapsulation adhesive, at high temperatures, the gaps between the molecular structures of the adhesive increase, and substances such as sulfur, oxygen, and bromine can easily enter the LED encapsulation and react with the silver plating layer. Therefore, it is urgent to improve the weather resistance of LED chips under high temperature and high humidity. Summary of the Invention

[0004] To improve the anti-sulfurization performance and weather resistance of LED chips, this application provides a coating and coating process for anti-sulfurization LED chips.

[0005] This application provides a coating for anti-sulfurization LED lamp beads, which adopts the following technical solution:

[0006] A coating for sulfide-resistant LED beads, comprising coating I and coating II; wherein, coating II is an encapsulating adhesive; and coating I is one of a topcoat or a basecoat.

[0007] By adopting the above technical solution, an anti-sulfurization coating is added to the surface of the LED beads. In addition to encapsulating with encapsulating glue, a surface coating or base coating is also added, which effectively improves the anti-sulfurization effect of the LED beads and increases the airtightness of the beads, thereby improving the overall performance of the LED beads.

[0008] Preferably, the surface coating includes an anti-sulfur layer; the anti-sulfur coating comprises, by weight, 30-50 parts polyurethane modified silicone resin, 2-4 parts dimethyl phthalate, 1-2 parts calcium carbonate, 1-3 parts titanium dioxide, 10-16 parts glass fiber, 1-3 parts antioxidant, and 1-2 parts adhesion promoter.

[0009] By adopting the above technical solution, polyurethane modified silicone resin is mixed with dimethyl phthalate, calcium carbonate, glass fiber and other materials as anti-sulfur coating, so that the coating has strong density and barrier properties, which can effectively prevent sulfur-containing gas from entering the LED package and effectively prevent LED light source failure. For LEDs that use high-refractive-index adhesive as encapsulant, the anti-sulfurization performance of LEDs can be effectively improved by simply applying the anti-sulfur coating.

[0010] Preferably, the surface coating further includes a surface transition layer; the surface transition layer is phenyl vinyl silicone resin.

[0011] By adopting the above technical solution, for LED beads using low-refractive-index adhesive as the encapsulant, adding a surface coating transition layer between the anti-sulfur layer and the encapsulant layer can effectively enhance the anti-sulfurization performance of the LED beads. Furthermore, phenyl vinyl silicone resin contains a large number of flexible groups, resulting in good coating flexibility, which can effectively improve the coating's anti-cracking performance.

[0012] Preferably, the primer coating includes an anti-sulfur layer and a primer adhesive layer.

[0013] By adopting the above technical solution, for LED beads using any type of encapsulating adhesive, the base coating can also be applied by superimposing an anti-sulfur layer and a base coating adhesive layer, which can also effectively improve the anti-sulfurization performance of LED beads and prevent sulfur-containing gases from entering the LED package and causing the LED light source to fail.

[0014] Preferably, the primer adhesive layer is an epoxy-modified silicone resin.

[0015] The reason for using the above technical solution and employing epoxy-modified silicone resin as the primer adhesive layer is that epoxy-modified silicone resin contains a large number of active functional groups, which can react with the encapsulant to effectively improve the adhesion between the encapsulant and the substrate.

[0016] Preferably, the polyurethane modified silicone resin is composed of the following raw materials in parts by weight: 30-35 parts tetramethyldivinyldisiloxane, 40-50 parts polymethylhydrosiloxane, 30-40 parts water, 130-170 parts toluene, 9-13 parts acetic acid, 3-5 parts tetraethyl orthosilicate, 30-50 parts polyethylene glycol, and 16-22 parts toluene diisocyanate.

[0017] This application provides a coating process for anti-sulfurization LED lamp beads, which adopts the following technical solution:

[0018] A coating process for sulfide-resistant LED chips includes the following steps:

[0019] S1. Die bonding process: The LED chip is fixed in the bracket cup using die bonding adhesive;

[0020] S2. Wire bonding process: Electrically connecting the LED chip to the bracket using wires;

[0021] S3. Coating Processing: A sulfur-resistant coating is applied to the cup of the LED bracket to obtain sulfur-resistant LED beads. The sulfur-resistant coating includes coating I and coating II; wherein, coating I is one of a top coating or a base coating; and coating II is an encapsulating adhesive.

[0022] S4. Finally, the obtained anti-sulfurization LED beads are subjected to appearance inspection, stripping, beam splitting, tape taping, packaging and warehousing.

[0023] By adopting the above technical solution, an anti-sulfurization coating is added to the surface of the LED beads. In addition to encapsulating with encapsulating glue, a surface coating or base coating is also added, which effectively improves the anti-sulfurization effect of the LED beads and increases the airtightness of the beads, thereby improving the overall performance of the LED beads.

[0024] Preferably, the coating process described in S3 specifically includes the following steps:

[0025] S31. After wire bonding, the LED bracket is dehumidified, then encapsulating adhesive is applied, and after it flows level, it is heated and cured to obtain coating II;

[0026] S32. Apply a topcoat over coating II, and after drying, obtain coating I; the topcoat includes an anti-sulfur layer or an anti-sulfur layer and a surface transition layer.

[0027] Preferably, the coating process described in S3 specifically includes the following steps:

[0028] S31. After wire bonding, a primer coating is applied to the LED bracket, and after drying, coating I is obtained; the primer coating includes an anti-sulfur layer and a primer adhesive layer;

[0029] S32. Dehumidification will be performed on top of coating I, followed by application of encapsulating adhesive. After it has leveled, it will be heated and cured to obtain coating II.

[0030] Preferably, the method for preparing the anti-sulfur coating includes the following steps:

[0031] S1. Mix 10-16 parts of glass fiber, 1-3 parts of titanium dioxide, and 2-4 parts of dimethyl phthalate into 30-50 parts of polyurethane modified silicone resin, stir quickly until uniform, and set aside to obtain a mixed liquid.

[0032] S2. Add 1-2 parts of calcium carbonate to the above mixture, homogenize by ultrasonic vibration, then add 1-3 parts of antioxidant and 1-2 parts of adhesion promoter and stir evenly to obtain the anti-sulfur coating.

[0033] In summary, this application includes at least one of the following beneficial technical effects:

[0034] 1. By adopting the above technical solution, an anti-sulfurization coating is added to the surface of the LED lamp bead. In addition to encapsulating with encapsulating glue, a surface coating or base coating is also added, which effectively improves the anti-sulfurization effect of the LED lamp bead and can also increase the airtightness of the lamp bead, thereby improving the overall performance of the LED lamp bead.

[0035] 2. By adopting the above technical solution, polyurethane modified silicone resin is mixed with dimethyl phthalate, calcium carbonate, glass fiber, etc. as an anti-sulfur coating, so that the coating has strong density and barrier properties, which can effectively prevent sulfur-containing gas from entering the LED package and effectively prevent the LED light source from failing. For LEDs that use high-refractive-index adhesive as the encapsulant, simply applying an anti-sulfur coating can effectively improve the anti-sulfurization performance of the LED.

[0036] 3. By adopting the above technical solution, for LED beads using any type of encapsulating adhesive, the base coating can also be applied by superimposing an anti-sulfur layer and a base coating adhesive layer, which can also effectively improve the anti-sulfurization performance of LED beads and prevent sulfur-containing gases from entering the LED package and causing the LED light source to fail. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the anti-sulfurization coating structure of Embodiment 1 of this application.

[0038] Figure 2 This is a schematic diagram of the anti-sulfurization coating structure of Embodiment 2 of this application.

[0039] Figure 3 This is a schematic diagram of the anti-sulfurization coating structure of Embodiment 3 of this application.

[0040] Reference numerals: 1. Anti-sulfur layer; 2. Coating II (encapsulating adhesive layer); 3. Topcoat transition layer; 4. Primer adhesive layer. Detailed Implementation

[0041] The present application will be further described in detail below with reference to the embodiments and the accompanying drawings.

[0042] Preparation Example

[0043] Preparation Example 1: Preparation of Polyurethane Modified Silicone Resin

[0044] Preparation Example 1.1

[0045] S1. Mix 30g water, 100g toluene and 9g acetic acid and stir until homogeneous to obtain a mixed solvent; add a mixture of 30g tetramethyldivinyldisiloxane, 40g polymethylhydrosiloxane and 3g tetraethyl orthosilicate dropwise at 60℃. After the addition is complete, react at 55℃ for 5 hours; after the reaction is complete, wash the product with water until neutral, and remove the mixed solvent by vacuum distillation at 80℃ to obtain silicone resin.

[0046] S2. Add 30g of polyethylene glycol to 30g of toluene and mix well. Then, add 16g of toluene diisocyanate dropwise at 40℃. After the addition is complete, continue the reaction for 4h. Remove the toluene by vacuum distillation at 80℃ to obtain a polyurethane prepolymer with isocyanate groups at the end.

[0047] S3. Take 50g of the silicone resin obtained in S1 and 50g of the polyurethane prepolymer obtained in S2, mix them, and stir at 45℃ for 2h to obtain polyurethane-modified silicone resin.

[0048] Preparation Example 1.2

[0049] S1. Mix 35g of water, 110g of toluene and 11g of acetic acid, and stir until homogeneous to obtain a mixed solvent; add dropwise 32.5g of tetramethyldivinyldisiloxane, 45g of polymethylhydrosiloxane and 4g of tetraethyl orthosilicate at 70℃; after the addition is complete, react at 60℃ for 7h; after the reaction is complete, wash the product with water until neutral, and remove the mixed solvent by vacuum distillation at 85℃ to obtain silicone resin;

[0050] S2. Add 40g of polyethylene glycol to 40g of toluene and mix well. Then, add 19g of toluene diisocyanate dropwise at 50℃. After the addition is complete, continue the reaction for 6h. Remove the toluene by vacuum distillation at 85℃ to obtain a polyurethane prepolymer with isocyanate groups at the end.

[0051] S3. Take 60g of the silicone resin obtained in S1 and 60g of the polyurethane prepolymer obtained in S2, mix them, and stir at 50℃ for 3h to obtain polyurethane-modified silicone resin.

[0052] Preparation Example 1.3

[0053] S1. Mix 40g water, 120g toluene and 13g acetic acid, and stir until homogeneous to obtain a mixed solvent; add a mixture of 35g tetramethyldivinyldisiloxane, 50g polymethylhydrosiloxane and 5g tetraethyl orthosilicate dropwise at 80℃. After the addition is complete, react at 65℃ for 9 hours; after the reaction is complete, wash the product with water until neutral, and remove the mixed solvent by vacuum distillation at 90℃ to obtain silicone resin.

[0054] S2. Add 50g of polyethylene glycol to 50g of toluene and mix well. Then, add 22g of toluene diisocyanate dropwise at 60℃. After the addition is complete, continue the reaction for 8 hours. Remove the toluene by vacuum distillation at 90℃ to obtain a polyurethane prepolymer with isocyanate groups at the end.

[0055] S3. Take 70g of the silicone resin obtained in S1 and 70g of the polyurethane prepolymer obtained in S2, mix them, and stir at 55℃ for 4h to obtain polyurethane-modified silicone resin.

[0056] Preparation Example 2: Preparation of Phenylvinyl silicone resin

[0057] Preparation Example 2.1

[0058] S1. A mixture containing 115g toluene, 60g phenyltrichlorosilane, and 10g phenyldimethylchlorosilane was added dropwise to 110g of water, mixed thoroughly, and allowed to hydrolyze for 2 hours to obtain the hydrolysis product.

[0059] S2. 12g of 107 silicone rubber with a viscosity of 500mPa.s was added dropwise to the hydrolysis product, followed by the addition of 3.5g of vinyl single end cap, and the pre-condensation reaction was carried out at 80°C for 3h.

[0060] S3. After the pre-condensation reaction is completed, the mixture is allowed to stand and separate into layers. The oil phase and the water phase are then separated. The oil phase is washed with water at 85°C until the pH of the washing wastewater is 7.

[0061] S4. Add 70g of 50% potassium hydroxide solution to the water-washed oil phase system, heat to 135℃, and catalyze the polycondensation reaction for 2h; then wash the sample after the catalytic polycondensation reaction with 85℃ water until the pH of the washing wastewater is 7, to obtain phenyl vinyl silicone resin crude material.

[0062] S5. The prepared phenyl vinyl silicone resin is heated at 140°C for 1 hour to obtain phenyl vinyl silicone resin.

[0063] Preparation Example 3: Preparation of Anti-sulfur Coating

[0064] Preparation Example 3.1

[0065] T1. Mix 10g of glass fiber, 1g of titanium dioxide and 2g of dimethyl phthalate into 30g of polyurethane modified silicone resin obtained from Preparation Example 1.1, and stir evenly at 40°C and 700rpm to obtain a mixed liquid.

[0066] T2. Add 1g of calcium carbonate to the above mixture, homogenize by ultrasonic vibration at an ultrasonic power of 21kHz, then add 1g of antioxidant and 1g of adhesion promoter and stir evenly to obtain the anti-sulfur coating layer; the antioxidant mentioned in this preparation example is a phenolic antioxidant; the adhesion promoter is polyurethane.

[0067] Preparation Example 3.2

[0068] T1. Mix 13g of glass fiber, 2g of titanium dioxide and 3g of dimethyl phthalate into 40g of polyurethane modified silicone resin obtained from Preparation Example 1.1, and stir evenly at 45°C and 850 rpm to obtain a mixed liquid.

[0069] T2. Add 1.5g of calcium carbonate to the above mixture and homogenize it by ultrasonic vibration at an ultrasonic power of 21.5kHz. Then add 2g of antioxidant and 1.5g of adhesion promoter and stir evenly to obtain the anti-sulfur coating. The antioxidant mentioned in this preparation example is a phenolic antioxidant and the adhesion promoter is polyurethane.

[0070] Preparation Example 3.3

[0071] T1. Mix 16g of glass fiber, 3g of titanium dioxide and 4g of dimethyl phthalate into 50g of polyurethane modified silicone resin obtained from Preparation Example 1.1, and stir evenly at 50°C and 1000rpm to obtain a mixed liquid.

[0072] T2. Add 2g of calcium carbonate to the above mixture and homogenize it by ultrasonic vibration at an ultrasonic power of 22kHz. Then add 3g of antioxidant and 2g of adhesion promoter and stir evenly to obtain the anti-sulfur coating. The antioxidant mentioned in this preparation example is a phenolic antioxidant and the adhesion promoter is polyurethane.

[0073] Preparation Example 3.4

[0074] The difference between Preparation Example 3.4 and Preparation Example 3.1 is that the polyurethane modified silicone resin used in Preparation Example 3.4 is derived from Preparation Example 1.2.

[0075] Preparation Example 3.5

[0076] The difference between Preparation Example 3.5 and Preparation Example 3.1 is that the polyurethane-modified silicone resin used in Preparation Example 3.4 is derived from Preparation Example 1.3.

[0077] Example

[0078] Example 1

[0079] S1. Die bonding process: The LED chip is fixed in the bracket cup using die bonding adhesive;

[0080] S2. Wire bonding process: Electrically connecting the LED chip to the bracket using wires;

[0081] S3. Coating process: such as Figure 1 As shown,

[0082] S31. After wire bonding, the LED bracket is dehumidified, and then high-bend encapsulant D60 is applied. After it is leveled, it is dried at 100°C for 30 min, and then dried at 150°C for 3 h to obtain coating II (2).

[0083] S32. The anti-sulfur coating obtained in Preparation Example 3.1 is applied on top of coating II (2), dried at 100°C for 30 min, and then dried at 130°C for 2 h to obtain anti-sulfur layer (1), which is coating I;

[0084] S4. Finally, the obtained anti-sulfurization LED beads are subjected to appearance inspection, stripping, beam splitting, tape taping, packaging and warehousing.

[0085] Example 2

[0086] S1. Die bonding process: The LED chip is fixed in the bracket cup using die bonding adhesive;

[0087] S2. Wire bonding process: Electrically connecting the LED chip to the bracket using wires;

[0088] S3. Coating process: such as Figure 2 As shown,

[0089] S31. After the LED bracket is wire bonded, dehumidify it, then apply encapsulating adhesive low-folding adhesive A70, wait for it to level, then dry it at 100℃ for 30 min, and then dry it at 140℃ for 3 h to obtain coating II (2).

[0090] S32. The phenyl vinyl silicone resin prepared by Preparation Example 2.1 was coated on top of coating II (2), dried at 100°C for 30 min, and then dried at 160°C for 1.5 h to obtain the surface coating transition layer (3).

[0091] S33. The anti-sulfur coating obtained in Preparation Example 3.1 is applied over the surface coating transition layer (3), dried at 100°C for 30 min, and then dried at 130°C for 2 h to obtain the anti-sulfur layer (1); the combination of the surface coating transition layer (3) and the anti-sulfur layer (1) is the coating layer I.

[0092] S4. Finally, the obtained anti-sulfurization LED beads are subjected to appearance inspection, stripping, beam splitting, tape reeling, packaging and warehousing.

[0093] Example 3

[0094] S1. Die bonding process: The LED chip is fixed in the bracket cup using die bonding adhesive;

[0095] S2. Wire bonding process: Electrically connecting the LED chip to the bracket using wires;

[0096] S3. Coating process: such as Figure 3 As shown,

[0097] S31. Apply epoxy-modified silicone resin to the LED bracket after wire bonding and dry it at 75°C for 12 hours to obtain the primer adhesive layer (4);

[0098] S32. The anti-sulfur coating obtained in Preparation Example 3.1 is applied over the primer adhesive layer (4), dried at 100°C for 30 min, and then dried at 130°C for 2 h to obtain the anti-sulfur layer (1); the combination of the primer adhesive layer (4) and the anti-sulfur layer (1) is the coating layer I.

[0099] S33. Dehumidify the surface of the LED bracket and the anti-sulfur layer (1), then apply encapsulating glue (any encapsulating glue, in this embodiment, high-bending glue D60 is used), wait for it to level, then dry it at 100°C for 30 min, and then dry it at 140°C for 3 h to obtain coating II (2).

[0100] S4. Finally, the obtained anti-sulfurization LED beads are subjected to appearance inspection, stripping, beam splitting, tape reeling, packaging and warehousing.

[0101] Example 4

[0102] The difference between Example 4 and Example 1 is that the anti-sulfur coating used in Example 4 is derived from Preparation Example 3.2.

[0103] Example 5

[0104] The difference between Example 5 and Example 1 is that the anti-sulfur coating used in Example 5 is derived from Preparation Example 3.3.

[0105] Example 6

[0106] The difference between Example 6 and Example 1 is that the anti-sulfur coating used in Example 6 is derived from Preparation Example 3.4.

[0107] Example 7

[0108] The difference between Example 7 and Example 1 is that the anti-sulfur coating used in Example 7 is derived from Preparation Example 3.5.

[0109] Comparative Example

[0110] Comparative Example 1

[0111] S1. Die bonding process: The LED chip is fixed in the bracket cup using die bonding adhesive;

[0112] S2. Wire bonding process: Electrically connecting the LED chip to the bracket using wires;

[0113] S3. Coating process: After wire bonding, the LED bracket is dehumidified, and then high-refractive-index D60 encapsulating adhesive is applied. After it is leveled, it is dried at 100℃ for 30 minutes, and then dried at 150℃ for 3 hours to obtain coating II; the resulting LED beads.

[0114] Comparative Example 2

[0115] S1. Die bonding process: The LED chip is fixed in the bracket cup using die bonding adhesive;

[0116] S2. Wire bonding process: Electrically connecting the LED chip to the bracket using wires;

[0117] S3. Coating process: After wire bonding, the LED bracket is dehumidified, then encapsulating adhesive A70 is applied. After it is leveled, it is dried at 100℃ for 30 minutes, and then dried at 150℃ for 3 hours to obtain coating II; the resulting LED beads.

[0118] Performance testing

[0119] 1. The luminous flux of the LED beads obtained in Examples 1-7 and Comparative Examples 1-2 was tested using GB / T 26178-2010 "Methods for Measurement of Luminous Flux". The results are shown in Table 1.

[0120] 2. The LED beads obtained in Examples 1-7 and Comparative Examples 1-2 were subjected to a sulfidation experiment. The sulfidation experiment conditions were: sulfur powder dosage 1 g / L, sulfidation temperature 105℃, and sulfidation time 2 h. The luminous flux after sulfidation was then tested, and the luminous flux retention rate after sulfidation was calculated. The results are shown in Table 1.

[0121] 3. The LED beads obtained in Examples 1-7 and Comparative Examples 1-2 were cycled 900 times between -40℃ for 15 min and 125℃ for 15 min to test their peeling rate, cracking rate and dead lamp rate. The results are shown in Table 1.

[0122] The specific test results are as follows:

[0123] Table 1 Performance Test Results

[0124]

[0125] Based on the luminous flux test results of the LED beads obtained from Examples 1-7 and Comparative Examples 1-2, the luminous flux difference between the LED beads after surface coating and primer coating (Examples 1-7) and the LED beads without anti-sulfurization coating (Comparative Examples 1-2) is small (less than 1%), indicating that the anti-sulfurization coating provided in this application has little effect on the luminous flux of the LED beads.

[0126] Based on the luminous flux retention rate test results of the LED beads after sulfurization obtained from Examples 1-7 and Comparative Examples 1-2, the LED beads after sulfurization with surface coating and primer coating (Examples 1-7) have a significantly higher luminous flux retention rate compared with the LED beads without anti-sulfurization coating (Comparative Examples 1-2), indicating that the anti-sulfurization effect of the anti-sulfurization coating provided in this application is significant.

[0127] Based on the results of the peeling rate, cracking rate, and dead lamp rate of the LED beads after thermal shock obtained from Examples 1-7 and Comparative Examples 1-2, the peeling rate and cracking rate of the LED beads after top coating and primer coating (Examples 1-7) were all 0, which was significantly lower than the peeling rate and cracking rate of the LED beads without anti-sulfurization coating (Comparative Examples 1-2). Similarly, the dead lamp rate of the LED beads after top coating and primer coating (Examples 1-7) was all less than 55%, which was significantly lower than the dead lamp rate of the LED beads without anti-sulfurization coating (Comparative Examples 1-2), indicating that the anti-sulfurization coating provided in this application also has strong weather resistance.

[0128] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A coating for sulfide-resistant LED lamp beads, characterized in that: The anti-sulfurization LED bead coating includes coating I and coating II; wherein, coating I is one of a top coating and a base coating; coating II is an encapsulating adhesive; the top coating includes an anti-sulfur layer; the anti-sulfur layer coating comprises, by weight, 30-50 parts polyurethane modified silicone resin, 2-4 parts dimethyl phthalate, 1-2 parts calcium carbonate, 1-3 parts titanium dioxide, 10-16 parts glass fiber, 1-3 parts antioxidant, and 1-2 parts adhesion promoter; the top coating also includes a top coating transition layer. The coating layer is a phenyl vinyl silicone resin, and the primer coating includes an anti-sulfur layer and a primer adhesive layer. The primer adhesive layer is an epoxy-modified silicone resin, and the polyurethane-modified silicone resin is composed of the following raw materials in parts by weight: 30-35 parts tetramethyldivinyldisiloxane, 40-50 parts polymethylhydrosiloxane, 30-40 parts water, 130-170 parts toluene, 9-13 parts acetic acid, 3-5 parts tetraethyl orthosilicate, 30-50 parts polyethylene glycol, and 16-22 parts toluene diisocyanate.

2. The coating process for anti-sulfurization LED beads according to claim 1, characterized in that: Includes the following steps: S1. Die bonding process: The LED chip is fixed in the bracket cup using die bonding adhesive; S2. Wire bonding process: Electrically connecting the LED chip to the bracket using wires; S3. Coating Processing: A sulfur-resistant coating is applied to the cup of the LED bracket to obtain sulfur-resistant LED beads. The sulfur-resistant coating includes coating I and coating II; wherein, coating I is one of a top coating or a base coating; and coating II is an encapsulating adhesive. S4. Finally, the obtained anti-sulfurization LED beads are subjected to appearance inspection, stripping, beam splitting, tape taping, packaging and warehousing. The coating process described in S3 specifically includes the following steps: S31. After wire bonding, the LED bracket is dehumidified, then encapsulating adhesive is applied, and after it flows level, it is heated and cured to obtain coating II; S32. Apply a topcoat layer over coating II, and after drying, obtain coating I; the topcoat layer includes an anti-sulfur layer and a topcoat transition layer; Alternatively, S31. After wire bonding, a primer coating is applied to the LED bracket, and after drying, coating I is obtained; the primer coating includes an anti-sulfur layer and a primer adhesive layer; S32. Dehumidify above coating I, then apply encapsulating adhesive, wait for it to level, and then heat to cure to obtain coating II; The preparation method of the anti-sulfur layer coating includes the following steps: S1. Mix 10-16 parts of glass fiber, 1-3 parts of titanium dioxide, and 2-4 parts of dimethyl phthalate into 30-50 parts of polyurethane modified silicone resin, stir quickly and evenly for later use to obtain a mixed liquid; S2. Add 1-2 parts of calcium carbonate to the above mixed liquid, homogenize by ultrasonic vibration, then add 1-3 parts of antioxidant and 1-2 parts of adhesion promoter and stir evenly to obtain the anti-sulfur layer coating.

Images