Epoxy resin encapsulating adhesive, preparation method thereof, LED display screen and encapsulating method thereof

Abstract

The application relates to an epoxy resin packaging glue, a preparation method thereof, an LED display screen and a packaging method thereof. According to mass percentages, the epoxy resin packaging glue comprises: an epoxy resin matrix 80-95% and heat-conducting particles 5-20%; wherein the epoxy resin matrix comprises: component A 44-45% and component B 55-56%; component A comprises: bisphenol A type epoxy resin 30-45%, bisphenol F type epoxy resin 5-10% and alicyclic epoxy resin 45-75%; component B comprises: an acid anhydride curing agent 79-94%, a curing accelerator 0.5-1%, organic silicon dioxide microspheres 5-15% and an antioxidant 0.5-1%; the heat-conducting particles comprise first heat-conducting particles and second heat-conducting particles with a mass ratio of 1:4-3:7; the particle size of the first heat-conducting particles is 100-150 nm; and the particle size of the second heat-conducting particles is 2-10 mu m.

Description

Epoxy resin encapsulant and its preparation method, LED display screen and its encapsulation method Technical Field

[0001] This application relates to the field of LED device technology, specifically to an epoxy resin encapsulating adhesive and its preparation method, and an LED display screen and its encapsulation method. Background Technology

[0002] LED displays primarily employ COB (chip-on-board) packaging technology. The packaging materials need to possess advantages such as high brightness, robust protection, uniform light emission, and high reliability. COB packaging technology mainly uses epoxy resin as the packaging material. Epoxy resin offers advantages such as high hardness, high transmittance, a wide variety of mature curing agents, and low cost.

[0003] LED displays primarily dissipate heat through heat conduction from the LED chip's motor pins to the PCB board. However, with the gradual reduction in pixel pitch and the dramatic increase in pixel density, LED displays generate a significant amount of heat during normal operation, necessitating that the epoxy encapsulation material of the LED chips also possess heat dissipation capabilities. Ordinary epoxy resin typically has a thermal conductivity of only 0.2 W / m². -1 K -1 This can cause the LED display to operate at excessively high temperatures, reducing its lifespan and accelerating the thermal aging process of the epoxy resin encapsulant. Summary of the Invention

[0004] Based on this, this application provides an epoxy resin encapsulant with both good thermal conductivity and optical properties, and a method for preparing the same.

[0005] One aspect of this application provides an epoxy resin encapsulating adhesive, comprising, by weight percentage: 80% to 95% epoxy resin matrix and 5% to 20% thermally conductive particles;

[0006] The epoxy resin matrix comprises, by weight percentage: 44%–45% of component A and 55%–56% of component B;

[0007] Component A, by mass percentage, comprises: 30%–45% bisphenol A type epoxy resin, 5%–10% bisphenol F type epoxy resin, and 45%–75% alicyclic epoxy resin;

[0008] Component B, by mass percentage, comprises: 79%–94% anhydride curing agent, 0.5%–1% curing accelerator, 5%–15% organosilica microspheres, and 0.5%–1% antioxidant;

[0009] The thermally conductive particles include a first thermally conductive particle and a second thermally conductive particle with a mass ratio of 1:4 to 3:7; the particle size of the first thermally conductive particle is 100nm to 150nm; and the particle size of the second thermally conductive particle is 2μm to 10μm.

[0010] In some embodiments, the method for preparing the thermally conductive particles includes the following steps:

[0011] Inorganic nanoparticles and a first modifier are mixed and reacted in a first solvent to prepare an intermediate.

[0012] The intermediate and the second modifier are mixed and reacted in a second solvent to prepare the thermally conductive particles;

[0013] The first modifier includes one or more of titanate coupling agents and silane coupling agents; the second modifier includes phosphate coupling agents.

[0014] In some embodiments, the method for preparing the thermally conductive particles satisfies at least one of the conditions in (1) to (7):

[0015] (1) The titanate coupling agent includes isopropyl tristearate titanate;

[0016] (2) The phosphate coupling agent includes one or more of dodecyl phosphate monoester and octadecyl phosphate monoester;

[0017] (3) The inorganic nanoparticles include one or more of boron nitride, aluminum nitride and aluminum oxide;

[0018] (4) The first solvent comprises isopropanol, ethanol and water in a volume ratio of (3.6-4.4):(0.8-1.2):1;

[0019] (5) The second solvent includes methanol;

[0020] (6) The mass ratio of the inorganic nanoparticles to the first modifier is (20-50):(2:5);

[0021] (7) The mass ratio of the inorganic nanoparticles to the second modifier is (20-50):(5:10). In some embodiments, component A satisfies at least one of the conditions in (1) to (2):

[0022] (1) The bisphenol A type epoxy resin includes one or more of E44 type epoxy resin and E51 type epoxy resin;

[0023] (2) The alicyclic epoxy resin includes one or more of cyclohexane-1,2-dicarboxylic acid diglycidyl ester, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester and 4-vinyl-1-cyclohexene diepoxide.

[0024] In some embodiments, component B satisfies at least one of the conditions in (1) to (4):

[0025] (1) The anhydride curing agent includes one or more of methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, maleic anhydride and phthalic anhydride;

[0026] (2) The curing accelerator includes one or more of diethylenetriamine, triethylenetetramine, and triethylenetetramine;

[0027] (3) The particle size of the organic silica microspheres is 2μm to 5μm;

[0028] (4) The antioxidants include one or more of antioxidants 245, antioxidant 816, antioxidant 1010, antioxidant 1076, antioxidant 1135, and antioxidant 1130.

[0029] Secondly, this application also provides a method for preparing the epoxy resin encapsulant mentioned in the first aspect, comprising the following steps:

[0030] Component A and component B are mixed to prepare an epoxy resin matrix;

[0031] The epoxy resin matrix and thermally conductive particles are mixed and degassed to prepare the epoxy resin encapsulating adhesive.

[0032] In some embodiments, the step of mixing the epoxy resin matrix and the thermally conductive particles and degassing satisfies at least one of the conditions in (1) to (4):

[0033] (1) The mixing speed is 2000 rpm to 3000 rpm;

[0034] (2) The mixing time is 1h to 2h;

[0035] (3) The stirring rate for degassing is 1000 rpm to 1500 rpm;

[0036] (4) The degassing time is 5 min to 10 min.

[0037] Thirdly, this application also provides a method for packaging an LED display screen, comprising the following steps:

[0038] An encapsulation layer is prepared by covering the surface of the LED display module with the epoxy resin encapsulating adhesive described in the first aspect;

[0039] The encapsulation layer is then cured.

[0040] In some embodiments, the curing process includes a first curing process and a second curing process; the curing process satisfies at least one of the conditions (1) to (4):

[0041] (1) The temperature of the first curing treatment is 70℃~90℃;

[0042] (2) The curing time for the first curing process is 0.5h to 1h;

[0043] (3) The temperature of the second curing treatment is 120℃~140℃;

[0044] (4) The time for the second curing process is 1h to 2h.

[0045] Fourthly, this application also provides an LED display screen, the encapsulation structure of which includes an encapsulation layer made of epoxy resin encapsulant as described in the first aspect.

[0046] The aforementioned epoxy resin encapsulant comprises an epoxy resin matrix and thermally conductive particles. The epoxy resin matrix includes a specific ratio of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and alicyclic epoxy resin. The thermally conductive particles include a specific ratio of two different particle sizes. Through the rational selection and proportioning of components, the aforementioned epoxy resin encapsulant possesses both good thermal conductivity and optical properties. When used in the encapsulation structure of LED displays, it exhibits high transmittance and can extend the lifespan of the LED display. Detailed Implementation

[0047] To facilitate understanding of this application, a more complete description will be provided below. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0049] One aspect of this application provides an epoxy resin encapsulant comprising, by weight percentage: 80% to 95% epoxy resin matrix and 5% to 20% thermally conductive particles.

[0050] Optionally, in the epoxy resin encapsulant, the mass percentage of the epoxy resin matrix is ​​within the range of 80%, 82%, 84%, 85%, 86%, 88%, 90%, 92%, 94%, 95%, or any combination thereof. In the epoxy resin encapsulant, the mass percentage of thermally conductive particles is within the range of 5%, 6%, 8%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, or any combination thereof.

[0051] The epoxy resin matrix, by weight percentage, comprises: 44%–45% of component A and 55%–56% of component B.

[0052] Component A, by mass percentage, comprises: 30%–45% bisphenol A type epoxy resin, 5%–10% bisphenol F type epoxy resin, and 45%–75% alicyclic epoxy resin.

[0053] Bisphenol A type epoxy resin is characterized by high viscosity and high transparency, and has a relatively low cost; bisphenol F type epoxy resin has lower viscosity and can be used to adjust the viscosity of encapsulants; alicyclic epoxy resin has high transparency and good aging resistance. Component A, through proper formulation of epoxy resins, results in epoxy encapsulants with good optical properties and aging resistance.

[0054] Optionally, the mass percentage of bisphenol A type epoxy resin in component A is 30%, 32%, 35%, 36%, 40%, 42%, 44%, 45%, or any of the above values.

[0055] Optionally, in component A, the mass percentage of bisphenol F epoxy resin is 5%, 6%, 7%, 8%, 9%, 10%, or any of the above values.

[0056] Optionally, in component A, the mass percentage of alicyclic epoxy resin is 45%, 50%, 55%, 60%, 65%, 70%, 75%, or any of the above values.

[0057] Component B, by mass percentage, comprises: 79%–94% anhydride curing agent, 0.5%–1% curing accelerator, 5%–15% organosilica microspheres, and 0.5%–1% antioxidant.

[0058] Component B contains a specific ratio of anhydride curing agent, curing accelerator, organosilica microspheres, and antioxidant. In practical use, components A and B are mixed, and the resulting epoxy resin matrix can be cured and molded under specific conditions.

[0059] Optionally, in component B, the mass percentage of the anhydride curing agent is 79%, 80%, 82%, 84%, 85%, 86%, 88%, 90%, 92%, 94%, or any combination thereof.

[0060] Optionally, in component B, the mass percentage of the curing accelerator is within the range of 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any of the above values.

[0061] Optionally, in component B, the mass percentage of the organic silica microspheres is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any of the above values.

[0062] Optionally, in component B, the mass percentage of the antioxidant is within the range of 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any of the above values.

[0063] The thermally conductive particles consist of a first thermally conductive particle and a second thermally conductive particle with a mass ratio of 1:4 to 3:7; the particle size of the first thermally conductive particle is 100 nm to 150 nm; and the particle size of the second thermally conductive particle is 2 μm to 10 μm. By employing nanoscale and microscale thermally conductive particles in a reasonable ratio, the island-type distribution of thermally conductive particles in the epoxy resin encapsulant can be reduced, forming a thermally conductive network with better thermal conductivity. Furthermore, it can maintain high light transmittance while improving thermal conductivity.

[0064] The aforementioned epoxy resin encapsulant comprises an epoxy resin matrix and thermally conductive particles. The epoxy resin matrix includes a specific ratio of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and alicyclic epoxy resin. The thermally conductive particles include a specific ratio of two different particle sizes. Through the rational selection and proportioning of components, the aforementioned epoxy resin encapsulant possesses both good thermal conductivity and optical properties. When used in the encapsulation structure of LED displays, it exhibits high transmittance and can extend the lifespan of the LED display.

[0065] In some embodiments, the method for preparing thermally conductive particles includes the following steps S110 and S120.

[0066] Step S110: Inorganic nanoparticles and a first modifier are mixed and reacted in a first solvent to prepare an intermediate. The first modifier includes one or more of titanate coupling agents and silane coupling agents.

[0067] In some embodiments, the inorganic nanoparticles include one or more of boron nitride, aluminum nitride, and aluminum oxide.

[0068] In some embodiments, the mass ratio of inorganic nanoparticles to the first modifier is (20-50):(2:5).

[0069] In some embodiments, the ratio of inorganic nanoparticles to the first solvent is (20g-50g): (100mL-150mL).

[0070] In some embodiments, the titanate coupling agent includes isopropyl tristearate titanate.

[0071] In some embodiments, the first solvent comprises isopropanol, ethanol, and water in a volume ratio of (3.6–4.4):(0.8–1.2):1. Optionally, the volume ratio of isopropanol, ethanol, and water in the first solvent is 4:1:1.

[0072] In some embodiments, step S110 includes:

[0073] Step S112: Stir the inorganic nanoparticles in the first solvent at 60℃~70℃ for 25min~35min; then add the first modifier and react for 5h~10h.

[0074] Step S114: Filter the mixture from step S112 after the reaction is complete, wash the precipitate with ethanol and deionized water in sequence, and dry it to obtain the intermediate.

[0075] Step S120: The intermediate and the second modifier are mixed and reacted in a second solvent to prepare thermally conductive particles. The second modifier includes a phosphate coupling agent.

[0076] In some embodiments, the phosphate coupling agent includes one or more of dodecyl phosphate monoester and octadecyl phosphate monoester.

[0077] In some of these embodiments, the second solvent includes methanol.

[0078] In some embodiments, the mass ratio of inorganic nanoparticles to the second modifier is (20-50):(5:10).

[0079] In some embodiments, the ratio of inorganic nanoparticles to the second solvent is (20g-50g): (100mL-150mL).

[0080] In some embodiments, step S120 includes:

[0081] Step S122: Disperse the second modifier in the second solvent, heat and mix until dissolved to obtain a second modifier solution.

[0082] Step S124: Mix the intermediate with the second modifier solution, evaporate the second solvent to obtain a solid.

[0083] Step S126: Grind the solid obtained in step S124 and sieve it to obtain thermally conductive particles.

[0084] By modifying the surface of inorganic nanoparticles with a first modifier and a second modifier, the prepared thermally conductive particles have good compatibility with the epoxy resin matrix, which helps to reduce interfacial defects between the thermally conductive particles and the epoxy resin matrix, reduce phonon scattering, and significantly improve the thermal conductivity of epoxy resin encapsulant with a low addition amount.

[0085] In some embodiments, the bisphenol A type epoxy resin includes one or more of E44 type epoxy resin and E51 type epoxy resin.

[0086] In some embodiments, the alicyclic epoxy resin includes one or more of cyclohexane-1,2-dicarboxylic acid diglycidyl ester, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester, and 4-vinyl-1-cyclohexene diepoxide.

[0087] In some embodiments, the anhydride curing agent includes one or more of methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, maleic anhydride, and phthalic anhydride.

[0088] In some embodiments, the curing accelerator includes one or more of diethylenetriamine, triethylenetetramine, and triethylenetetramine.

[0089] In some of these embodiments, the particle size of the organosilica microspheres is 2 μm to 5 μm.

[0090] In some embodiments, the antioxidants include one or more of antioxidant 245 (triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]), antioxidant 816 (polymerized hindered phenol), antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), antioxidant 1076 (octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), antioxidant 1135 (isooctanol β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), and antioxidant 1130 (1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene).

[0091] Secondly, this application also provides a method for preparing the epoxy resin encapsulant mentioned in the first aspect, including the following steps S210 and S220.

[0092] Step S210: Mix component A and component B to prepare an epoxy resin matrix.

[0093] Step S220: Mix the epoxy resin matrix and thermally conductive particles, degas, and prepare epoxy resin encapsulant.

[0094] In some embodiments, in step S220, the mixing process is carried out in a mechanical mixer.

[0095] In some embodiments, in step S220, the stirring rate of the mixing process is 2000 rpm to 3000 rpm. Optionally, the stirring rate is within the range of 2000 rpm, 2200 rpm, 2400 rpm, 2500 rpm, 2600 rpm, 2800 rpm, 3000 rpm, or any combination thereof.

[0096] In some embodiments, the mixing process in step S220 takes 1 to 2 hours.

[0097] In some embodiments, the degassing process is carried out in a planetary vacuum mixer.

[0098] In some embodiments, the stirring rate for the degassing process is 1000 rpm to 1500 rpm. Optionally, the stirring rate for the degassing process is within the range of 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, or any combination thereof.

[0099] In some embodiments, the degassing treatment time is 5 min to 10 min.

[0100] Thirdly, this application also provides the application of the epoxy resin encapsulant mentioned in the first aspect in the preparation of LED displays.

[0101] Fourthly, this application also provides a packaging method for an LED display screen, including the following steps S310 and S320.

[0102] Step S310: Cover the surface of the LED display module with the epoxy resin encapsulant described in the first aspect to prepare an encapsulation layer.

[0103] Step S320: Curing the encapsulation layer.

[0104] In some embodiments, the curing process includes a first curing process and a second curing process.

[0105] In some embodiments, the temperature of the first curing treatment is 70°C to 90°C. Optionally, the temperature of the first curing treatment is within the range of 70°C, 75°C, 80°C, 85°C, 90°C, or any combination thereof.

[0106] In some embodiments, the first curing process takes 0.5 h to 1 h.

[0107] In some embodiments, the temperature of the second curing process is 120°C to 140°C. Optionally, the temperature of the second curing process is within the range of 120°C, 125°C, 130°C, 135°C, 140°C, or any combination thereof.

[0108] In some embodiments, the second curing process takes 1 to 2 hours.

[0109] Fifthly, this application also provides an LED display screen whose encapsulation structure includes an encapsulation layer made of epoxy resin encapsulant as described in the first aspect.

[0110] The encapsulation structure of the LED display screen uses an encapsulation layer made of the epoxy resin encapsulant. The encapsulation structure has good thermal conductivity and optical performance. While ensuring high light transmittance, it has good thermal conductivity and can extend the service life of the LED display screen.

[0111] Sixthly, this application also provides an electronic product including the LED display screen described in the fifth aspect above.

[0112]

[0113] The following detailed description is provided with reference to specific embodiments. Unless otherwise specified, the embodiments do not include components other than unavoidable impurities. The reagents and instruments used in the embodiments, unless otherwise specified, are conventionally selected in the art. Experimental methods not specifying specific conditions in the embodiments were performed under conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer. In the following embodiments and comparative examples, unless otherwise stated, all parts refer to parts by mass.

[0114] Example 1:

[0115] The preparation of the epoxy resin encapsulant and encapsulation layer in this embodiment includes:

[0116] (1) Preparation of inorganic nanoparticles: boron nitride (particle size 100nm~150nm) and aluminum nitride (2μm~10μm) in a mass ratio of 1:4.

[0117] (2) 20g of inorganic nanoparticles were heated to 65°C and stirred for 30min with 100ml of the first solvent (volume ratio 4:1:1). Then 2g of tristearate isopropyl titanate was added and reacted for 10h. The solvent was removed by filtration, and the solid was washed three times with ethanol and deionized water and dried at 150°C to obtain the intermediate.

[0118] (3) Disperse 10g of octadecyl phosphate monoester in 150ml of methanol, heat to 65℃ while stirring to dissolve, then add the intermediate obtained in step (2), then evaporate to remove methanol, dry the obtained solid to constant weight, then grind and sieve to obtain conductive particles.

[0119] (4) Prepare components A and B. Component A, by mass percentage, includes: 30% bisphenol A type epoxy resin (E44), 5% bisphenol F type epoxy resin, and 65% alicyclic epoxy resin (cyclohexane-1,2-dicarboxylic acid diglycidyl ester). Component B, by mass percentage, includes: 90.5% anhydride curing agent (methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride in a 1:2 mass ratio), 1% curing accelerator (triethylenetetramine), 8% organosilica microspheres (2μm~5μm), and 0.5% antioxidant [antioxidant 245 (triethylene glycol di[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate]]].

[0120] (5) Mix component A and component B in a mass ratio of 44:56 to obtain an epoxy resin matrix.

[0121] (6) Mix 95% epoxy resin matrix and 5% thermally conductive particles by mass percentage using a mechanical mixer at 2000 rpm for 1 hour. Then degas using a planetary vacuum mixer (1000 rpm, 5 min) to obtain epoxy resin encapsulating adhesive.

[0122] (7) The epoxy resin encapsulant obtained in step (6) is subjected to a first curing treatment and a second curing treatment. The temperature of the first curing treatment is 70°C and the time is 1 hour; the temperature of the second curing treatment is 140°C and the time is 2 hours. An encapsulation layer is obtained.

[0123] Example 2:

[0124] The preparation of the epoxy resin encapsulant and encapsulation layer in this embodiment includes:

[0125] (1) Prepare inorganic nanoparticles: boron nitride (particle size 100nm~150nm) and aluminum nitride (2μm~10μm) in a mass ratio of 3:7.

[0126] (2) 20g of inorganic nanoparticles were heated to 65°C and stirred for 30min with 100ml of the first solvent (volume ratio 4:1:1). Then 2g of tristearate isopropyl titanate was added and reacted for 10h. The solvent was removed by filtration, and the solid was washed three times with ethanol and deionized water and dried at 150°C to obtain the intermediate.

[0127] (3) Disperse 5g of dodecyl phosphate monoester in 100ml of methanol, heat to 65℃ while stirring to dissolve, then add the intermediate obtained in step (2), then evaporate to remove methanol, dry the obtained solid to constant weight, then grind and sieve to obtain conductive particles.

[0128] (4) Prepare components A and B. Component A, by mass percentage, includes: 40% bisphenol A type epoxy resin (E44), 7% bisphenol F type epoxy resin, and 53% alicyclic epoxy resin (4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester). Component B, by mass percentage, includes: 86% anhydride curing agent (methyltetrahydrophthalic anhydride and maleic anhydride in a 1:2 mass ratio), 0.8% curing accelerator (triethylenetetramine), 12.2% organosilica microspheres (2μm~5μm), and 1% antioxidant [antioxidant 816 (polymerized hindered phenol)].

[0129] (5) Mix component A and component B in a mass ratio of 45:55 to obtain an epoxy resin matrix.

[0130] (6) Mix 80% epoxy resin matrix and 20% thermally conductive particles by mass percentage using a mechanical mixer at 3000 rpm for 2 hours. Then degas using a planetary vacuum mixer (1500 rpm, 10 min) to obtain epoxy resin encapsulant.

[0131] (7) The epoxy resin encapsulant obtained in step (6) is subjected to a first curing treatment and a second curing treatment. The temperature of the first curing treatment is 90℃ and the time is 0.5h; the temperature of the second curing treatment is 140℃ and the time is 1.5h. An encapsulation layer is obtained.

[0132] Example 3:

[0133] The preparation of the epoxy resin encapsulant and encapsulation layer in this embodiment includes:

[0134] (1) Preparation of inorganic nanoparticles: boron nitride (particle size 100nm~150nm) and aluminum oxide (2μm~10μm) in a mass ratio of 1:4.

[0135] (2) 40g of inorganic nanoparticles were heated to 70℃ and stirred for 30min with 150ml of the first solvent (volume ratio of 4:1:1). Then 4.5g of KH570 silane coupling agent was added and reacted for 8h. The solvent was removed by filtration, and the solid was washed three times with ethanol and deionized water. The solid was dried at 150℃ to obtain the intermediate.

[0136] (3) Disperse 8g of octadecyl phosphate monoester in 150ml of methanol, heat to 65℃ while stirring to dissolve, then add 30g of the intermediate obtained in step (2), then evaporate to remove methanol, dry the obtained solid to constant weight, then grind and sieve to obtain conductive particles.

[0137] (4) Prepare components A and B. Component A, by mass percentage, includes: 45% bisphenol A type epoxy resin (E51), 10% bisphenol F type epoxy resin, and 45% alicyclic epoxy resin (4-vinyl-1-cyclohexene diepoxide). Component B, by mass percentage, includes: 90% anhydride curing agent (methylhexahydrophthalic anhydride and phthalic anhydride in a 3:1 mass ratio), 0.7% curing accelerator (triethylenetetramine), 8.7% organosilica microspheres (2μm~5μm), and 0.6% antioxidant [antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]]

[0138] (5) Mix component A and component B in a mass ratio of 45:55 to obtain an epoxy resin matrix.

[0139] (6) Mix 90% epoxy resin matrix and 10% thermally conductive particles by mass percentage using a mechanical mixer at 2000 rpm for 1 hour. Then degas using a planetary vacuum mixer (1000 rpm, 10 min) to obtain epoxy resin encapsulant.

[0140] (7) The epoxy resin encapsulant obtained in step (6) is subjected to a first curing treatment and a second curing treatment. The temperature of the first curing treatment is 80℃ and the time is 1h; the temperature of the second curing treatment is 130℃ and the time is 2h. The encapsulation layer is obtained.

[0141] Comparative Example 1:

[0142] The difference between Comparative Example 1 and Example 1 is that the inorganic nanoparticles in step (1) are boron nitride (particle size 100nm~150nm).

[0143] Comparative Example 2:

[0144] The difference between Comparative Example 2 and Example 1 is that the inorganic nanoparticles in step (1) are aluminum nitride (2μm~10μm).

[0145] Test section:

[0146] Thermal conductivity test: The epoxy resin encapsulant of the cured examples or comparative examples was used to make a 1 mm thick adhesive layer, and the thermal conductivity was directly tested using a multi-functional rapid thermal conductivity tester.

[0147] Transmittance test: The transmittance of the above adhesive layer was tested using a transmittance tester at an ambient temperature of 25°C.

[0148] The thermal conductivity and light transmittance of the encapsulation layers prepared in Examples 1-3 and Comparative Examples 1-2 are recorded in Table 1.

[0149] Table 1

[0150] Serial Number Thermal Conductivity (W m) -1 K -1 Light transmittance (%) Example 1 0.5289 Example 2 1.2183 Example 3 0.6181 Comparative Example 1 0.3282 Comparative Example 2 0.5468 surface

[0151] As can be seen from the data in Table 1, the thermal conductivity of the encapsulation layers obtained in Examples 1-3 is 0.52 W / m. -1 K -1 ~1.21W m -1 K -1 The light transmittance is 81%–89%, exhibiting good thermal conductivity and optical properties. The difference between the encapsulation layers prepared in Comparative Examples 1 and 2 and those in Example 1 is that the thermally conductive particles are made of inorganic nanoparticles of a single particle size. The thermal conductivity of the encapsulation layer prepared in Comparative Example 1 is 0.32 W / m². -1 K -1 The light transmittance is 82%, and the thermal conductivity is relatively low; the thermal conductivity of the encapsulation layer prepared in Comparative Example 2 is 0.54 W / m. -1 K -1 The light transmittance is 68%, which is relatively low. Comparative Examples 1 and 2 are difficult to achieve both good thermal conductivity and optical performance, and their overall performance is not as good as the encapsulation layer of Example 1.

[0152] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0153] The embodiments described above merely illustrate several implementation methods of this application to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. An epoxy resin encapsulating adhesive, characterized in that, The product comprises, by weight percentage: 80%–95% epoxy resin matrix and 5%–20% thermally conductive particles; wherein, the epoxy resin matrix comprises, by weight percentage: 44%–45% component A and 55%–56% component B; component A comprises, by weight percentage: 30%–45% bisphenol A epoxy resin, 5%–10% bisphenol F epoxy resin, and 45%–65% alicyclic epoxy resin; component B comprises, by weight percentage: 84%–94% anhydride curing agent, 0.5%–1% curing accelerator, 5%–15% organosilica microspheres, and 0.5%–1% antioxidant; the thermally conductive particles comprise a first thermally conductive particle and a second thermally conductive particle with a weight ratio of 1:4 to 3:7; the first thermally conductive particle has a particle size of 100 nm–150 nm; the second thermally conductive particle has a particle size of 2 μm–10 μm. μm; The method for preparing the thermally conductive particles includes the following steps: mixing and reacting inorganic nanoparticles and a first modifier in a first solvent to prepare an intermediate; mixing and reacting the intermediate and a second modifier in a second solvent to prepare the thermally conductive particles; wherein, the first modifier includes one or more of titanate coupling agents and silane coupling agents; the second modifier includes a phosphate coupling agent; the inorganic nanoparticles in the first thermally conductive particles are boron nitride, and the second thermally conductive particles are aluminum nitride or aluminum oxide.

2. The epoxy resin encapsulating adhesive according to claim 1, characterized in that, The method for preparing the thermally conductive particles satisfies at least one of the conditions in (1) to (6): (1) the titanate coupling agent includes isopropyl tristearate titanate; (2) the phosphate coupling agent includes one or more of dodecyl phosphate monoester and octadecyl phosphate monoester; (3) the first solvent includes isopropanol, ethanol and water in a volume ratio of (3.6~4.4):(0.8~1.2):1; (4) the second solvent includes methanol; (5) the mass ratio of the inorganic nanoparticles to the first modifier is (20~50):(2:5); (6) the mass ratio of the inorganic nanoparticles to the second modifier is (20~50):(5:10).

3. The epoxy resin encapsulating adhesive according to claim 1, characterized in that, The A component satisfies at least one of the conditions in (1) to (2): (1) The bisphenol A type epoxy resin includes one or more of E44 type epoxy resin and E51 type epoxy resin; (2) The alicyclic epoxy resin includes one or more of cyclohexane-1,2-dicarboxylic acid diglycidyl ester, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester and 4-vinyl-1-cyclohexene diepoxide.

4. The epoxy resin encapsulant according to any one of claims 1 to 3, characterized in that, The B component satisfies at least one of the following conditions (1) to (4): (1) The anhydride curing agent includes one or more of methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, maleic anhydride and phthalic anhydride; (2) The curing accelerator includes one or more of diethylenetriamine, triethylenetetramine and triethylenetetramine; (3) The particle size of the organic silica microspheres is 2μm to 5μm; (4) The antioxidant includes one or more of antioxidant 245, antioxidant 816, antioxidant 1010, antioxidant 1076, antioxidant 1135 and antioxidant 1130.

5. The method for preparing the epoxy resin encapsulant according to any one of claims 1 to 4, characterized in that, Includes the following steps: Component A and component B are mixed to prepare an epoxy resin matrix; the epoxy resin matrix is ​​then mixed with thermally conductive particles and degassed to prepare the epoxy resin encapsulant.

6. The method for preparing the epoxy resin encapsulant according to claim 5, characterized in that, The step of mixing the epoxy resin matrix and the thermally conductive particles and degassing satisfies at least one of the following conditions (1) to (4): (1) the mixing stirring rate is 2000 rpm to 3000 rpm; (2) the mixing time is 1 h to 2 h; (3) the degassing stirring rate is 1000 rpm to 1500 rpm; (4) the degassing time is 5 min to 10 min.

7. A method for packaging an LED display screen, characterized in that, Includes the following steps: An encapsulation layer is prepared by covering the surface of an LED display module with the epoxy resin encapsulant as described in any one of claims 1 to 4; the encapsulation layer is then cured.

8. The LED display packaging method according to claim 7, characterized in that, The curing process includes a first curing process and a second curing process; the curing process satisfies at least one of the following conditions (1) to (4): (1) the temperature of the first curing process is 70℃ to 90℃; (2) the time of the first curing process is 0.5h to 1h; (3) the temperature of the second curing process is 120℃ to 140℃; (4) the time of the second curing process is 1h to 2h.

9. An LED display screen, characterized in that, Its encapsulation structure includes an encapsulation layer made of epoxy resin encapsulant as described in any one of claims 1 to 4.