High-thermal-conductivity mini LED packaging film and preparation method thereof

Abstract

The application discloses a high-thermal-conductivity Mini LED packaging film and a preparation method thereof, and relates to the technical field of Mini LED packaging films.The application is characterized in that, in the preparation of the high-thermal-conductivity Mini LED packaging film, a dimerized fatty acid is reacted with an epichlorohydrin to obtain an epoxy fatty acid; boron nitride is reacted with a silane hydrolysis solution to obtain pre-modified boron nitride; the pre-modified boron nitride is reacted with 2,2,6,6-tetramethyl-4-methylenepiperidine to obtain modified boron nitride; 4,4-diaminodiphenyl sulfide is reacted with trichloroisocyanuric acid to obtain a triazine curing agent; and the high-thermal-conductivity Mini LED packaging film is prepared by uniformly mixing bisphenol F type epoxy resin, the epoxy fatty acid, the triazine curing agent and the modified boron nitride and then coating and curing.The high-thermal-conductivity Mini LED packaging film prepared by the application has excellent thermal conductivity, light transmission, anti-aging and low thermal stress performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of Mini LED packaging film, in particular to a high-thermal-conductivity Mini LED packaging film and a preparation method thereof. BACKGROUND

[0002] As the core development direction of modern display field, Mini LED technology has been widely used in high-end TV, vehicle-mounted display screen, wearable device and large-size commercial display, etc. Through dense chip arrangement and fine local dimming, it realizes extremely high contrast and brightness. However, the miniaturization and high-density integration of chips also bring severe thermal management challenges. If the large amount of heat generated during work cannot be timely discharged, it will directly lead to a sharp drop in device light efficiency, color distortion and service life attenuation.

[0003] As a key component of Mini LED device, the packaging film bears the important functions of protecting the chip and insulating and sealing, and needs to have a higher refractive index to optimize the light extraction capability for higher light efficiency and wider viewing angle. Although the mainstream epoxy resin material has the advantages of high mechanical strength, good adhesion and mature process, it has low intrinsic thermal conductivity, poor ultraviolet aging resistance, and mismatch of thermal expansion coefficient between the chip and the substrate, which easily accumulates residual stress during temperature change, causing interface delamination, material warping and even cracking, which seriously restricts the reliability and service life of Mini LED. Therefore, it is of great practical significance and market value to develop a new type of Mini LED packaging film with high thermal conductivity, high refractive index, anti-aging and low thermal stress. SUMMARY

[0004] The purpose of the present application is to provide a high-thermal-conductivity Mini LED packaging film and a preparation method thereof to solve the problems in the prior art.

[0005] In order to solve the above technical problems, the present application provides the following solutions:

[0006] A high-thermal-conductivity Mini LED packaging film is prepared by reacting a dimer fatty acid and an epoxy chloropropane to obtain an epoxy fatty acid, reacting boron nitride and a silane hydrolyzate to obtain a pre-modified boron nitride, reacting the pre-modified boron nitride and 2,2,6,6-tetramethyl-4-methylenepiperidine to obtain modified boron nitride, reacting 4,4-diaminodiphenyl sulfide and trichloro-s-triazine to obtain a triazine curing agent, and coating and curing bisphenol F type epoxy resin, epoxy fatty acid, triazine curing agent and modified boron nitride to obtain the high-thermal-conductivity Mini LED packaging film.

[0007] The silane hydrolyzate is prepared by reacting 2-mercaptoethyl triethoxysilane, deionized water and glacial acetic acid.

[0008] The application discloses a preparation method of a high-thermal-conductivity Mini LED packaging film.

[0009] (1) uniformly mix dimerized fatty acid and epichlorohydrin, cool to 0-4 DEG C, add 0.004-0.006 times the mass of sodium hydroxide saturated aqueous solution to the dimerized fatty acid, stir at 300-500 r / min for 20-30 min, warm to 60-70 DEG C, continue to stir for 2-3 h, distill under reduced pressure at 85-95 DEG C for 2-3 h, cool to 60-70 DEG C, add 0.18-0.22 times the mass of methyl isobutyl ketone to the dimerized fatty acid, add 0.42-0.46 times the mass of sodium hydroxide to the dimerized fatty acid within 2-3 h, reflux at 130-140 DEG C for 2-3 h, cool to room temperature, filter, take the filtrate, neutralize to pH=7-7.4 with 10% potassium dihydrogen phosphate aqueous solution, extract 3-5 times with 60-70 DEG C deionized water, take the organic phase, and vacuum dry at 75-85 DEG C for 10-12 h to prepare an epoxy fatty acid.

[0010] (2) take boron nitride and 2-mercaptoethyl triethoxysilane according to a mass ratio of 1:(0.16-0.2), uniformly mix pre-modified boron nitride, 2,2,6,6-tetramethyl-4-methylenepiperidine, 2-hydroxy-2-methyl-1-phenyl-1-propanone and anhydrous ethanol according to a mass ratio of 1:(0.1-0.14):(0.013-0.017):(10-14), warm to 45-55 DEG C under nitrogen protection, stir at 4000-5000 r / min under irradiation of a 365 nm ultraviolet lamp for 2-3 h, filter, wash 3-5 times with anhydrous ethanol, and vacuum dry at 55-65 DEG C for 14-16 h to prepare modified boron nitride.

[0011] (3) take 4,4-diaminodiphenyl sulfide and trichloroisocyanuric acid according to a molar ratio of 3:1, uniformly mix trichloroisocyanuric acid and anhydrous tetrahydrofuran according to a mass ratio of 1:(16-18), stir at 200-300 r / min at room temperature for 10-20 min, cool to -4-0 DEG C, uniformly add 4,4-diaminodiphenyl sulfide solution within 1-2 h, continue to stir for 2-3 h, warm to room temperature, continue to stir for 1-2 h, add deionized water at 0 DEG C to precipitate, filter, wash 3-5 times with cold deionized water and cold ethanol respectively, and vacuum dry at 60-70 DEG C for 24-28 h to prepare a trizine curing agent.

[0012] (4) 70-80 parts by mass of epoxy resin, 20-30 parts by mass of epoxy fatty acid, 30-40 parts by mass of triazine curing agent and 20-30 parts by mass of modified boron nitride are uniformly mixed, stirred at 300-500 r / min for 10-20 min at room temperature, transferred into a vacuum defoaming machine, defoamed at -0.096 to -0.1 MPa for 5-15 min, coated and cured to obtain a high-thermal-conductivity Mini LED packaging film.

[0013] As an optimization, the molar ratio of the dimeric fatty acid to the epichlorohydrin in step (1) is 1:(2-2.2).

[0014] As an optimization, the preparation method of the pre-modified boron nitride in step (2) is as follows: boron nitride and anhydrous ethanol are uniformly mixed at a mass ratio of 1:(10-12), heated to 40-50℃, stirred at 4000-5000 r / min for 30-40 min, and then a silane hydrolysate is added, and the stirring is continued for 4-6 h under nitrogen protection, filtered, washed with anhydrous ethanol for 3-5 times, and vacuum dried at 55-65℃ for 10-12 h to obtain the pre-modified boron nitride.

[0015] As an optimization, the boron nitride is of a model DK-BN-001 and a particle size of 50 nm, and is purchased from Beijing Dekedao Gold Technology Co., Ltd.

[0016] As an optimization, the preparation method of the silane hydrolysate is as follows: 2-mercaptoethyl triethoxysilane, deionized water and 1% by volume of glacial acetic acid are uniformly mixed at a mass ratio of 1:(0.5-0.6):(0.001-0.003), stirred at 200-300 r / min for 8-10 min at room temperature to obtain the silane hydrolysate.

[0017] As an optimization, the preparation method of the 4,4-diaminodiphenyl sulfide solution in step (3) is as follows: 4,4-diaminodiphenyl sulfide and anhydrous tetrahydrofuran are uniformly mixed at a mass ratio of 1:(8-10), stirred at 200-300 r / min for 10-20 min at room temperature to obtain the 4,4-diaminodiphenyl sulfide solution.

[0018] As an optimization, the epoxy resin in step (4) is of a model BFE-17 bisphenol F epoxy resin, and is purchased from Wuhan Langbomowan Biomedical Co., Ltd.

[0019] As an optimization, the process parameters of the coating and curing in step (4) are as follows: uniformly coated on a glass plate, placed into an oven for curing, and the curing process is as follows: first stage, cured at 70-80℃ for 1.5-2.5 h, second stage, heated to 115-125℃ for curing for 1.5-2.5 h, third stage, heated to 140-150℃ for curing for 2.5-3.5 h, and then cooled to room temperature and peeled off from the glass plate.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] In the preparation of the high-thermal-conductivity Mini LED packaging film, the dimer fatty acid and the epichlorohydrin are reacted to prepare an epoxy fatty acid; the 2-mercaptoethyl triethoxysilane, deionized water and glacial acetic acid are reacted to prepare a silane hydrolysis solution; the boron nitride and the silane hydrolysis solution are reacted to prepare a pre-modified boron nitride; the pre-modified boron nitride and the 2,2,6,6-tetramethyl-4-methylene piperidine are reacted to prepare a modified boron nitride; the 4,4-diamino diphenyl sulfide and the trichloro-s-triazine are reacted to prepare a triazine curing agent; and the bisphenol F type epoxy resin, the epoxy fatty acid, the triazine curing agent and the modified boron nitride are coated and cured to prepare the high-thermal-conductivity Mini LED packaging film.

[0022] Firstly, the dimer fatty acid and the epichlorohydrin are reacted to prepare an epoxy fatty acid; the epoxy structure is introduced on the fatty acid, and in the curing process, the long-chain fatty acid is introduced into the high-thermal-conductivity Mini LED packaging film as a flexible chain segment through a covalent bond, which can significantly improve the molecular chain movement ability of the material, reduce the modulus of the crosslinked network, thereby enhancing the dissipation ability of the material to external stress, absorbing and releasing the internal stress generated by thermal expansion mismatch through the entropy change of the flexible chain segment, and further endowing the high-thermal-conductivity Mini LED packaging film with excellent low thermal stress performance.

[0023] Secondly, the 2-mercaptoethyl triethoxysilane, deionized water and glacial acetic acid are reacted to prepare a silane hydrolysis solution; the boron nitride and the silane hydrolysis solution are reacted to prepare a pre-modified boron nitride, and the mercapto group is grafted on the surface of the pre-modified boron nitride; the pre-modified boron nitride and the 2,2,6,6-tetramethyl-4-methylene piperidine are reacted by addition reaction to prepare a modified boron nitride; the nitroxyl radical on the 2,2,6,6-tetramethyl-4-methylene piperidine ring captures the polymer free radicals excited by ultraviolet light to generate ether compounds, and then regenerates into active nitroxyl radicals through molecular rearrangement, forming a sustainable reversible Denison cycle protection mechanism for thousands of times, which endows the high-thermal-conductivity Mini LED packaging film with excellent anti-aging performance; the boron nitride as a two-dimensional nano filler forms a continuous phonon transmission network in the polymer matrix through its unique layered crystal structure, which constructs an efficient heat conduction path, and the phonon vibration mode can significantly reduce the thermal transport resistance, realizing the rapid diffusion of the heat generated by the chip along the plane direction, and further endowing the high-thermal-conductivity Mini LED packaging film with excellent thermal conductivity.

[0024] Finally, the triazine curing agent is prepared by reacting 4, 4-diamino diphenyl sulfide and trichloro-s-triazine; the triazine ring serves as an efficient ultraviolet absorption center, the electron-rich nitrogen atoms and the electron-deficient carbon atoms are arranged alternately to form a highly conjugated system, when irradiated by ultraviolet light, the π electrons on the ring undergo n→π and π→π transitions, enter the excited state by absorbing photon energy, and then convert the energy into harmless heat energy through non-radiative relaxation, thereby preventing ultraviolet light from penetrating the material to initiate polymer photodegradation, and further improving the anti-aging performance of the high-thermal-conductivity Mini LED packaging film; the sulfur atom of the diphenyl sulfide structure has a high molar refractivity, and its lone pair electrons form p-π conjugation with the benzene ring, significantly enhancing the molecular electron cloud polarizability, and at the same time, the rigid biphenyl structure of diphenyl sulfide and the triazine ring jointly construct an extended conjugated system, according to the Lorentz-Lorenz equation, this high electron density characteristic makes the material produce stronger polarization under the action of an electric field, thereby significantly improving the refractive index in the visible light region, and further endowing the high-thermal-conductivity Mini LED packaging film with higher refractive performance. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0026] Embodiment 1:

[0027] A preparation method of a high-thermal-conductivity Mini LED packaging film, the preparation method of the high-thermal-conductivity Mini LED packaging film comprising the following steps:

[0028] (1) uniformly mix dimer fatty acid and epichlorohydrin at a mass ratio of 1:3.1, cool to 0°C, add 0.004 times the mass of sodium hydroxide saturated aqueous solution to the dimer fatty acid, stir at 300 r / min for 30 min, warm to 60°C, continue to stir and react for 3 h, distill at 85°C under reduced pressure for 3 h, cool to 60°C, add 0.18 times the mass of methyl isobutyl ketone to the dimer fatty acid, add 0.42 times the mass of sodium hydroxide to the dimer fatty acid within 3 h, reflux at 130°C for 3 h, cool to room temperature, filter, take the filtrate, neutralize to pH=7 with 10% potassium dihydrogen phosphate aqueous solution, extract with 60°C deionized water for 3 times, take the organic phase, and dry at 75°C under vacuum for 12 h to prepare an epoxy fatty acid.

[0029] (2) Boron nitride and 2-mercaptoethyl triethoxysilane were weighed according to a mass ratio of 1:0.16; 2-mercaptoethyl triethoxysilane, deionized water and 1% by volume of glacial acetic acid were mixed according to a mass ratio of 1:0.5:0.001, uniformly, stirred at 200 r / min for 10 min at room temperature, to prepare a silane hydrolysis solution; boron nitride and anhydrous ethanol were mixed according to a mass ratio of 1:10, uniformly, heated to 40℃, stirred at 4000 r / min for 40 min, and the silane hydrolysis solution was added, and the stirring was continued for 6 h under nitrogen protection, filtered, washed with anhydrous ethanol for 3 times, and vacuum dried at 55℃ for 12 h, to prepare pre-modified boron nitride; the pre-modified boron nitride, 2,2,6,6-tetramethyl-4-methylenepiperidine, 2-hydroxy-2-methyl-1-phenyl-1-propanone and anhydrous ethanol were mixed according to a mass ratio of 1:0.1:0.013:10, uniformly, heated to 45℃ under nitrogen protection, and reacted under the irradiation of a 365 nm ultraviolet lamp, stirred at 4000 r / min for 3 h, filtered, washed with anhydrous ethanol for 3 times, and vacuum dried at 55℃ for 16 h, to prepare modified boron nitride.

[0030] (3) 4,4-diaminodiphenyl sulfide and trichloroisocyanuric acid were weighed according to a molar ratio of 3:1; 4,4-diaminodiphenyl sulfide and anhydrous tetrahydrofuran were mixed according to a mass ratio of 1:8, uniformly, stirred at 200 r / min for 20 min at room temperature, to prepare a 4,4-diaminodiphenyl sulfide solution; trichloroisocyanuric acid and anhydrous tetrahydrofuran were mixed according to a mass ratio of 1:16, uniformly, stirred at 200 r / min for 20 min at room temperature, cooled to-4℃, and the 4,4-diaminodiphenyl sulfide solution was added at a constant speed within 2 h, and the stirring was continued for 3 h, heated to room temperature, and the stirring was continued for 2 h, deionized water at 0℃ was added for precipitation, filtered, washed with cold deionized water and cold ethanol for 3 times, respectively, and vacuum dried at 60℃ for 28 h, to prepare a triazine curing agent.

[0031] (4) Bisphenol F type epoxy resin 70 parts, epoxy fatty acid 20 parts, triazine curing agent 30 parts, modified boron nitride 20 parts were weighed according to a mass fraction, mixed uniformly, stirred at 300 r / min for 10 min at room temperature, transferred into a vacuum defoaming machine, defoamed at-0.096 for 15 min, uniformly coated on a glass plate, and placed into an oven for curing, and the curing process was as follows: the first stage was cured at 70℃ for 2.5 h, the second stage was heated to 115℃ for curing for 2.5 h, and the third stage was heated to 140℃ for curing for 3.5 h, cooled to room temperature, peeled off from the glass plate, to prepare a high-thermal-conductivity Mini LED packaging film.

[0032] Example 2:

[0033] A preparation method of a high-thermal-conductivity Mini LED packaging film, the preparation method of the high-thermal-conductivity Mini LED packaging film comprises the following steps:

[0034] (1) dimerized fatty acid and epichlorohydrin were mixed uniformly at a mass ratio of 1:3, cooled to 2℃, 0.005 times the mass of sodium hydroxide saturated aqueous solution was added, stirred at 400 r / min for 25 min, warmed to 65℃, continued to stir for 2.5 h, distilled at 90℃ under reduced pressure for 2.5 h, cooled to 65℃, 0.2 times the mass of methyl isobutyl ketone was added, 0.44 times the mass of sodium hydroxide was added within 2.5 h, reacted at 135℃ under reflux for 2.5 h, cooled to room temperature, filtered, the filtrate was neutralized to pH = 7.2 with 10% potassium dihydrogen phosphate aqueous solution, extracted with 65℃ deionized water 4 times, the organic phase was dried at 80℃ under vacuum for 11 h, to obtain epoxy fatty acid.

[0035] (2) boron nitride and 2-mercaptoethyl triethoxysilane were weighed at a mass ratio of 1:0.18; 2-mercaptoethyl triethoxysilane, deionized water and 1% glacial acetic acid by volume were mixed uniformly at a mass ratio of 1:0.55:0.002, stirred at 250 r / min for 9 min at room temperature to prepare a silane hydrolysis solution; boron nitride and anhydrous ethanol were mixed uniformly at a mass ratio of 1:11, heated to 45℃, stirred at 4500 r / min for 35 min, the silane hydrolysis solution was added, continued to stir for 5 h under nitrogen protection, filtered, washed with anhydrous ethanol 4 times, dried at 60℃ under vacuum for 11 h to prepare pre-modified boron nitride; the pre-modified boron nitride, 2,2,6,6-tetramethyl-4-methylenepiperidine, 2-hydroxy-2-methyl-1-phenyl-1-propanone and anhydrous ethanol were mixed uniformly at a mass ratio of 1:0.12:0.015:12, warmed to 50℃ under nitrogen protection, reacted under 365 nm ultraviolet light irradiation, stirred at 4500 r / min for 2.5 h, filtered, washed with anhydrous ethanol 4 times, dried at 60℃ under vacuum for 15 h to prepare modified boron nitride.

[0036] (3) 4,4-diaminodiphenyl sulfide and trichloroisocyanuric acid were weighed at a molar ratio of 3:1; 4,4-diaminodiphenyl sulfide and anhydrous tetrahydrofuran were mixed uniformly at a mass ratio of 1:9, stirred at 250 r / min for 15 min at room temperature to prepare a 4,4-diaminodiphenyl sulfide solution; trichloroisocyanuric acid and anhydrous tetrahydrofuran were mixed uniformly at a mass ratio of 1:17, stirred at 250 r / min for 15 min at room temperature, cooled to -2℃, the 4,4-diaminodiphenyl sulfide solution was added at a constant speed within 1.5 h, continued to stir for 2.5 h, warmed to room temperature, continued to stir for 1.5 h, precipitated with 0℃ deionized water, filtered, washed with cold deionized water and cold ethanol 4 times respectively, dried at 65℃ under vacuum for 26 h to prepare a triazine curing agent.

[0037] (4) 75 parts of bisphenol F type epoxy resin, 25 parts of epoxy fatty acid, 35 parts of triazine curing agent and 25 parts of modified boron nitride by mass fraction were weighed and uniformly mixed. After stirring at 400 r / min for 15 min at room temperature, the mixture was transferred into a vacuum degassing machine and degassed at -0.098 MPa for 10 min. The mixture was uniformly coated on a glass plate and placed into an oven for curing. The curing process was as follows: the first stage was curing at 75°C for 2 h, the second stage was curing at 120°C for 2 h, and the third stage was curing at 145°C for 3 h. After cooling to room temperature, the high-thermal-conductivity Mini LED packaging film was peeled off from the glass plate.

[0038] Example 3:

[0039] A preparation method of a high-thermal-conductivity Mini LED packaging film, the preparation method comprising the following steps:

[0040] (1) Dimer fatty acid and epichlorohydrin were mixed uniformly at a mass ratio of 1:3.3. A saturated aqueous solution of sodium hydroxide with a mass of 0.006 times that of the dimer fatty acid was added after cooling to 4°C. The mixture was stirred at 500 r / min for 20 min, and then heated to 70°C for continuous stirring reaction for 2 h. The mixture was distilled at 95°C under reduced pressure for 2 h, cooled to 70°C, and then 0.22 times the mass of methyl isobutyl ketone and 0.46 times the mass of sodium hydroxide were added within 2 h. The mixture was refluxed at 140°C for 2 h, cooled to room temperature, filtered, and then the filtrate was neutralized to pH=7.4 with a 10% potassium dihydrogen phosphate aqueous solution. The mixture was extracted with deionized water at 70°C for 5 times, and then the organic phase was vacuum dried at 85°C for 10 h to obtain the epoxy fatty acid.

[0041] (2) Boron nitride and 2-mercaptoethyl triethoxysilane were weighed at a mass ratio of 1:0.2. 2-mercaptoethyl triethoxysilane, deionized water and 1% glacial acetic acid by volume were mixed uniformly at a mass ratio of 1:0.6:0.003. The mixture was stirred at 300 r / min for 8 min at room temperature to obtain a silane hydrolysis solution. Boron nitride and anhydrous ethanol were mixed uniformly at a mass ratio of 1:12, and then heated to 50°C. The mixture was stirred at 5000 r / min for 30 min, and then the silane hydrolysis solution was added. The mixture was continuously stirred for 4 h under nitrogen protection, filtered, washed with anhydrous ethanol for 5 times, and then vacuum dried at 65°C for 10 h to obtain pre-modified boron nitride. The pre-modified boron nitride, 2,2,6,6-tetramethyl-4-methylenepiperidine, 2-hydroxy-2-methyl-1-phenyl-1-propanone and anhydrous ethanol were mixed uniformly at a mass ratio of 1:0.14:0.017:14. The mixture was heated to 55°C under nitrogen protection, and then stirred at 5000 r / min for 2 h under irradiation of a 365 nm ultraviolet lamp. The mixture was filtered, washed with anhydrous ethanol for 5 times, and then vacuum dried at 65°C for 14 h to obtain modified boron nitride.

[0042] (3) 4,4-diaminodiphenyl sulfide and trichloro-s-triazine were weighed according to a molar ratio of 3:1; 4,4-diaminodiphenyl sulfide and anhydrous tetrahydrofuran were mixed uniformly according to a mass ratio of 1:10, stirred at 300 r / min for 10 min at room temperature, to prepare a 4,4-diaminodiphenyl sulfide solution; trichloro-s-triazine and anhydrous tetrahydrofuran were mixed uniformly according to a mass ratio of 1:18, stirred at 300 r / min for 10 min at room temperature, cooled to 0°C, and the 4,4-diaminodiphenyl sulfide solution was added at a uniform speed within 1 h, and the reaction was continued for 2 h, the temperature was increased to room temperature, and the reaction was continued for 1 h, deionized water at 0°C was added for precipitation, filtered, washed with cold deionized water and cold ethanol for 5 times respectively, and vacuum dried at 70°C for 24 h, to prepare a triazine curing agent.

[0043] (4) Bisphenol F type epoxy resin 80 parts, epoxy fatty acid 30 parts, triazine curing agent 40 parts, and modified boron nitride 30 parts were weighed according to a mass fraction, mixed uniformly, stirred at 500 r / min for 10 min at room temperature, transferred into a vacuum degassing machine, degassed at -0.1 MPa for 5 min, uniformly coated on a glass plate, placed into an oven for curing, and the curing process was as follows: the first stage was curing at 80°C for 2.5 h, the second stage was heating to 125°C for curing for 2.5 h, and the third stage was heating to 150°C for curing for 3.5 h, cooled to room temperature, peeled off from the glass plate, to prepare a high-thermal-conductivity Mini LED packaging film.

[0044] Comparative Example 1

[0045] The preparation method of the high-thermal-conductivity Mini LED packaging film of Comparative Example 1 was different from that of Example 2 in that step (1) was not performed, and step (4) was changed to: bisphenol F type epoxy resin 100 parts, triazine curing agent 35 parts, and modified boron nitride 25 parts were weighed according to a mass fraction, mixed uniformly, stirred at 400 r / min for 15 min at room temperature, transferred into a vacuum degassing machine, degassed at -0.098 MPa for 10 min, uniformly coated on a glass plate, placed into an oven for curing, and the curing process was as follows: the first stage was curing at 75°C for 2 h, the second stage was heating to 120°C for curing for 2 h, and the third stage was heating to 145°C for curing for 3 h, cooled to room temperature, peeled off from the glass plate, to prepare a high-thermal-conductivity Mini LED packaging film. The remaining steps were the same as those of Example 2.

[0046] Comparative Example 2

[0047] The preparation method of the high-thermal-conductivity Mini LED packaging film of Comparative Example 2 is different from that of Example 2 in that step (2) is not performed, and step (4) is changed to: 75 parts of bisphenol F type epoxy resin, 25 parts of epoxy fatty acid, and 35 parts of triazine curing agent are weighed according to the mass fraction, mixed uniformly, stirred at 400 r / min for 15 min at room temperature, transferred into a vacuum degassing machine, degassed at-0.098 MPa for 10 min, uniformly coated on a glass plate, and placed into an oven for curing. The curing process is: curing at 75℃ for 2 h in the first stage, heating to 120℃ for 2 h in the second stage, and heating to 145℃ for 3 h in the third stage. After cooling to room temperature, the high-thermal-conductivity Mini LED packaging film is peeled off from the glass plate. The remaining steps are the same as those of Example 2.

[0048] Comparative Example 3

[0049] The preparation method of the high-thermal-conductivity Mini LED packaging film of Comparative Example 3 is different from that of Example 2 in that step (3) is not performed, and step (4) is changed to: 75 parts of bisphenol F type epoxy resin, 25 parts of epoxy fatty acid, and 35 parts of triazine curing agent are weighed according to the mass fraction, mixed uniformly, stirred at 400 r / min for 15 min at room temperature, transferred into a vacuum degassing machine, degassed at-0.098 MPa for 10 min, uniformly coated on a glass plate, and placed into an oven for curing. The curing process is: curing at 75℃ for 2 h in the first stage, heating to 120℃ for 2 h in the second stage, and heating to 145℃ for 3 h in the third stage. After cooling to room temperature, the high-thermal-conductivity Mini LED packaging film is peeled off from the glass plate. The remaining steps are the same as those of Example 2.

[0050] Test Example 1

[0051] Low thermal stress performance test

[0052] Test method: The high-thermal-conductivity Mini LED packaging film of Example and Comparative Example is coated on a one-side polished silicon wafer substrate with a diameter of 76.2 mm and cured. The temperature is raised from 20℃ to 250℃ at a rate of 5℃ / min, then kept at 250℃ for 20 min, and then cooled from 250℃ to 30℃ at a rate of-10℃ / min. The cycle is repeated for 35 times. A film stress analyzer is used to measure the thermal cycle residual stress of the sample. The results are shown in Table 1.

[0053] Table 1

[0054]

[0055] From the experimental data of Examples 1-3 and Comparative Examples 1-3 in Table 1, it can be found that the high-thermal-conductivity Mini LED packaging film prepared by the present application has good low thermal stress performance.

[0056] By comparison, the cyclic stress of examples 1-3 is less than that of comparative example 1, which shows that the epoxy fatty acid is prepared by reacting the dimeric fatty acid and epichlorohydrin; the epoxy structure is introduced on the fatty acid, and in the curing process, the long-chain aliphatic is introduced into the high-thermal-conductivity Mini LED packaging film as a flexible chain segment through covalent bond, which can significantly improve the molecular chain movement ability of the material, reduce the modulus of the crosslinked network, thereby enhancing the dissipation ability of the material to external stress, absorbing and releasing the internal stress generated by thermal expansion mismatch through the entropy change of the flexible chain segment, and further endowing the high-thermal-conductivity Mini LED packaging film with excellent low-thermal-stress performance.

[0057] Test example 2

[0058] Anti-aging performance test

[0059] Test method: the high-thermal-conductivity Mini LED packaging film examples and comparative examples are made into standard test pieces with a size of 5x10 cm, the test pieces are placed on the test rack of the ultraviolet aging test box for ultraviolet artificial accelerated aging, the light source is 3x36W fluorescent ultraviolet lamp, the emission peak characteristic wavelength is 275nm, the temperature in the aging box is 45℃, the distance from the light source to the test piece is 40cm, and after artificial aging for 30d, the yellowing index is tested according to GB / T 7921-2008 using a spectrophotometer. The results are shown in Table 2.

[0060] Table 2

[0061]

[0062] From the experimental data comparison of examples 1-3 and comparative examples 1-3 in Table 2, it can be found that the high-thermal-conductivity Mini LED packaging film prepared by the present application has good anti-aging performance.

[0063] By comparison, the yellowing index of examples 1-3 is less than that of comparative example 2, which shows that the silane hydrolysis solution is prepared by reacting 2-mercaptoethyl triethoxysilane, deionized water and glacial acetic acid; the pre-modified boron nitride is prepared by reacting boron nitride and the silane hydrolysis solution, and the mercapto group is grafted on the surface of the pre-modified boron nitride; the modified boron nitride is prepared by addition reaction of the pre-modified boron nitride and 2,2,6,6-tetramethyl-4-methylenepiperidine; the nitrogen-oxygen radical on the ring of 2,2,6,6-tetramethyl-4-methylenepiperidine captures the polymer radical excited by ultraviolet light to generate ether compounds, and then regenerates into active nitrogen-oxygen radical through molecular rearrangement, forming a sustainable thousands of times reversible Denison cycle protection mechanism, and endowing the high-thermal-conductivity Mini LED packaging film with excellent anti-aging performance.

[0064] By comparison, the yellowing index of examples 1-3 is less than that of comparative example 3, indicating that the triazine curing agent is prepared by reacting 4,4-diamino diphenyl sulfide and trichloro-s-triazine; the triazine ring serves as an efficient ultraviolet absorption center, and the rich electron nitrogen atom and the electron-deficient carbon atom are arranged alternately to form a highly conjugated system; when irradiated by ultraviolet light, the π electrons on the ring undergo n→π and π→π transitions, enter the excited state by absorbing photon energy, and then convert the energy into harmless heat energy through non-radiative relaxation, thereby preventing ultraviolet light from penetrating the material to cause polymer photodegradation, and further improving the anti-aging performance of the high-thermal-conductivity Mini LED packaging film.

[0065] Test example 3

[0066] Thermal conductivity test

[0067] Test method: according to GB / T 40564-2021 "test method for epoxy plastic packaging material for electronic packaging" and GB / T 3139-2005 "test method for thermal conductivity of fiber reinforced plastic", the high-thermal-conductivity Mini LED packaging film examples and test examples are made into standard samples, and the thermal conductivity of the standard samples is determined by using a DRE-2C thermal conductivity tester. The results are shown in Table 3.

[0068] Table 3

[0069]

[0070] From the experimental data comparison of examples 1-3 and comparative examples 1-3 in Table 3, it can be found that the high-thermal-conductivity Mini LED packaging film prepared by the present application has good thermal conductivity.

[0071] By comparison, the thermal conductivity of examples 1-3 is greater than that of comparative example 2, indicating that the silane hydrolysis solution is prepared by reacting 2-mercaptoethyl triethoxysilane, deionized water and glacial acetic acid; the pre-modified boron nitride is prepared by reacting boron nitride and the silane hydrolysis solution, and the mercapto group is grafted on the surface of the pre-modified boron nitride; the modified boron nitride is prepared by addition reaction of the pre-modified boron nitride and 2,2,6,6-tetramethyl-4-methylene piperidine; boron nitride as a two-dimensional nano filler forms a continuous phonon transmission network in the polymer matrix through its unique layered crystal structure, and builds an efficient heat conduction path, and its phonon vibration mode can significantly reduce the thermal transport resistance, realize the rapid diffusion of heat generated by the chip along the plane direction, and further endow the high-thermal-conductivity Mini LED packaging film with excellent thermal conductivity.

[0072] Test example 4

[0073] Refractive performance test

[0074] Test method: pour the high-thermal-conductivity Mini LED packaging film test examples and comparative examples into a polypropylene mold to solidify, prepare a test refractive index sample, the sample thickness in the polypropylene mold is 1 mm, polish on a metallographic grinder to obtain two mutually perpendicular mirror surfaces, and other surfaces are required to be matte surfaces, thereby obtaining a solid refractive index sample. Add a drop of bromonaphthalene on the prism of a 2WE-TD digital Abbe refractometer, place the mirror surface of the solidified sample on the prism of the Abbe refractometer, and let the bromonaphthalene fill the interface between the sample and the prism, and test the refractive index of each sample. The results are shown in Table 4.

[0075] Table 4

[0076]

[0077] From the comparison of the experimental data of examples 1-3 and comparative examples 1-3 in Table 2, it can be found that the high-thermal-conductivity Mini LED packaging film prepared by the present application has good refractive performance.

[0078] By comparison, the refractive index of examples 1-3 is greater than that of comparative example 3, which shows that the triazine curing agent is prepared by reacting 4,4-diamino diphenyl sulfide and trichloro-s-triazine; the sulfur atom of the diphenyl sulfide structure has a high molar refractivity, and its lone pair of electrons forms p-π conjugation with the benzene ring, significantly enhancing the molecular electron cloud polarizability; at the same time, the rigid biphenyl structure of diphenyl sulfide and the triazine ring together construct an extended conjugated system, according to the Lorentz-Lorenz equation, this high electron density characteristic makes the material produce stronger polarization under the action of an electric field, thereby significantly improving the refractive index in the visible light region, and further endowing the high-thermal-conductivity Mini LED packaging film with higher refractive performance.

[0079] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application, and it should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A high thermal conductivity Mini LED encapsulation film, characterized in that, The high thermal conductivity Mini LED encapsulation film is prepared by reacting dimer fatty acids and epichlorohydrin to obtain epoxy fatty acids; reacting boron nitride and silane hydrolysate to obtain pre-modified boron nitride; reacting the pre-modified boron nitride with 2,2,6,6-tetramethyl-4-methylenepiperidine to obtain modified boron nitride; reacting 4,4-diaminodiphenyl sulfide and trichlorotriazine to obtain triazine curing agent; and uniformly mixing bisphenol F type epoxy resin, epoxy fatty acids, triazine curing agent and modified boron nitride before coating and curing. The silane hydrolysate is prepared by reacting 2-mercaptoethyltriethoxysilane, deionized water, and glacial acetic acid.

2. A method for preparing a high thermal conductivity Mini LED encapsulation film, characterized in that, The method for preparing the high thermal conductivity Mini LED encapsulation film includes the following preparation steps: (1) Mix the dimer fatty acid and epichlorohydrin evenly, cool to 0~4℃, add 0.004~0.006 times the mass of the dimer fatty acid in a saturated sodium hydroxide aqueous solution, stir at 300~500 r / min for 20~30 min, heat to 60~70℃, continue stirring and reacting for 2~3 h, distill under reduced pressure at 85~95℃ for 2~3 h, cool to 60~70℃, and add 0.18~0.22 times the mass of the dimer fatty acid. Add 0.42 to 0.46 times the mass of sodium hydroxide to the dimeric fatty acid within 2 to 3 hours, reflux at 130 to 140°C for 2 to 3 hours, cool to room temperature, filter, neutralize the filtrate with a 10% (v / v) potassium dihydrogen phosphate aqueous solution to pH 7 to 7.4, extract with deionized water at 60 to 70°C 3 to 5 times, and dry the organic phase under vacuum at 75 to 85°C for 10 to 12 hours to obtain epoxy fatty acids; (2) Weigh boron nitride and 2-mercaptoethyltriethoxysilane at a mass ratio of 1:(0.16~0.2); mix 2-mercaptoethyltriethoxysilane, deionized water, and 1% glacial acetic acid at a mass ratio of 1:(0.5~0.6):(0.001~0.003), and stir at 200~300 r / min for 8~10 min at room temperature to obtain silane hydrolysate; mix boron nitride and anhydrous ethanol at a mass ratio of 1:(10~12), heat to 40~50℃, stir at 4000~5000 r / min for 30~40 min, add silane hydrolysate, and continue stirring for 4~6 h under nitrogen protection, then filter. Pre-modified boron nitride was prepared by washing the boron nitride 3-5 times with anhydrous ethanol and drying it under vacuum at 55-65℃ for 10-12 hours. The pre-modified boron nitride, 2,2,6,6-tetramethyl-4-methylenepiperidine, 2-hydroxy-2-methyl-1-phenyl-1-propanone and anhydrous ethanol were mixed evenly at a mass ratio of 1:(0.1-0.14):(0.013-0.017):(10-14). Under nitrogen protection, the mixture was heated to 45-55℃ and stirred at 4000-5000 r / min for 2-3 hours under 365 nm ultraviolet light. The mixture was filtered, washed 3-5 times with anhydrous ethanol, and dried under vacuum at 55-65℃ for 14-16 hours to obtain modified boron nitride. (3) Weigh 4,4-diaminodiphenyl sulfide and trichlorotriazine in a molar ratio of 3:1; mix trichlorotriazine and anhydrous tetrahydrofuran in a mass ratio of 1:(16~18), stir at 200~300r / min for 10~20min at room temperature, cool to -4~0℃, add 4,4-diaminodiphenyl sulfide solution at a uniform rate over 1~2h, continue stirring and react for 2~3h, heat to room temperature, continue stirring and react for 1~2h, add 0℃ deionized water to precipitate, filter, wash 3~5 times with cold deionized water and cold ethanol respectively, and vacuum dry at 60~70℃ for 24~28h to obtain triazine curing agent; (4) Weigh 70-80 parts of epoxy resin, 20-30 parts of epoxy fatty acid, 30-40 parts of triazine curing agent and 20-30 parts of modified boron nitride by mass fraction, mix evenly, stir at 300-500 r / min for 10-20 min at room temperature, transfer to vacuum degassing machine, degas at -0.096--0.1 MPa for 5-15 min, coat and cure to obtain a high thermal conductivity Mini LED encapsulation film.

3. The method for preparing the high thermal conductivity Mini LED encapsulation film according to claim 2, characterized in that, The molar ratio of the dimer fatty acid and epichlorohydrin in step (1) is 1:(2~2.2).

4. The method for preparing the high thermal conductivity Mini LED encapsulation film according to claim 2, characterized in that, The boron nitride used in step (2) is of type DK-BN-001 with a particle size of 50 nm.

5. The method for preparing the high thermal conductivity Mini LED encapsulation film according to claim 2, characterized in that, The preparation method of the 4,4-diaminodiphenyl sulfide solution in step (3) is as follows: 4,4-diaminodiphenyl sulfide and anhydrous tetrahydrofuran are mixed evenly at a mass ratio of 1:(8~10), and stirred at 200~300r / min for 10~20min at room temperature to obtain the 4,4-diaminodiphenyl sulfide solution.

6. The method for preparing the high thermal conductivity Mini LED encapsulation film according to claim 2, characterized in that, The epoxy resin used in step (4) is of type BFE-17 bisphenol F epoxy resin.

7. The method for preparing the high thermal conductivity Mini LED encapsulation film according to claim 2, characterized in that, The process parameters for coating and curing in step (4) are as follows: the coating is uniformly applied to the glass plate and placed in an oven for curing. The curing process is as follows: the first stage is cured at 70~80℃ for 1.5~2.5h, the second stage is heated to 115~125℃ for 1.5~2.5h, the third stage is heated to 140~150℃ for 2.5~3.5h, and then cooled to room temperature and peeled off from the glass plate.

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