Reflective solid crystal adhesive material based on nanoparticle dispersion technology, preparation process and application

Abstract

The invention relates to the technical field of solid crystal glue materials, in particular to a reflective solid crystal glue material based on a nanoparticle dispersion technology, a preparation process and application. The coating comprises a resin matrix, a nanometer functional filler and an auxiliary agent system, wherein the resin matrix at least comprises epoxy resin, cyanate ester resin and benzoxazine resin; the nano functional filler is one of a nano particle material or a nano filler; through the synergistic effect of the surface-modified zinc oxide nanoparticles and the surface-modified cerium oxide nanoparticles and in combination with the total reflection characteristic of the titanium dioxide coated glass beads, an efficient reflection-refraction synergistic enhancement system is constructed; the plasma resonance effect of the surface-modified cerium oxide nanoparticles is matched with the high-refractive-index zinc oxide nanoparticles, so that the initial luminous flux of an LED is improved by 18%-22% compared with that of traditional solid crystal glue, the light utilization rate is improved by 20%-25%, the six-surface luminous potential of a chip is excavated, and therefore the quality of the solid crystal glue is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of die bonding adhesive materials, and specifically to a reflective die bonding adhesive material based on nanoparticle dispersion technology, a preparation process, and applications thereof. Background Art

[0002] Currently, in the field of optoelectronic devices, as an efficient optoelectronic conversion device, LEDs (light-emitting diodes) are widely used in fields such as lighting, display, and optical communication. As the core encapsulation material for LEDs, the performance of the die bonding adhesive plays a decisive role in the luminous efficiency, lifespan, and reliability of LED devices. With the continuous development of technology, the requirements for the performance of optoelectronic devices such as LEDs are increasing day by day, especially the application of high-power LEDs is gradually increasing.

[0003] In terms of improving the performance of LED devices, traditional die bonding adhesives mainly reduce light loss by increasing the light transmittance. However, in the actual application scenarios of high-power LEDs, this method has some deficiencies. First, simply relying on increasing the light transmittance cannot fully exploit the potential of six-sided light emission of the chip, which limits the improvement of luminous flux, resulting in a low light reflection utilization rate and making it difficult to meet the application requirements of high brightness and high light output. Second, a large amount of heat generated during the operation of high-brightness LEDs can easily cause problems such as yellowing and aging of the die bonding adhesive, thereby accelerating light decay and seriously affecting the luminous stability and lifespan of the LEDs. In addition, from the perspective of material stability, in a long-term high-temperature environment, the refractive index of the colloid of traditional die bonding adhesives is likely to change, which will directly affect the consistency of light color, making it difficult to maintain the stability of the light-emitting effect of the LEDs, reducing the quality of light emission, and thus reducing the reliability of the die bonding adhesive.

[0004] In view of this, there is an urgent need for a reflective die bonding adhesive material based on nanoparticle dispersion technology, a preparation process, and applications thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a reflective die bonding adhesive material based on nanoparticle dispersion technology, a preparation process, and applications thereof, so as to solve the problems raised in the above background art.

[0006] To achieve the above purpose, first, the present invention provides a reflective die bonding adhesive material based on nanoparticle dispersion technology, including a resin matrix, nano-functional fillers, and an additive system, wherein:

[0007] The resin matrix includes at least epoxy resin, cyanate ester resin, and benzoxazine resin; the content ratio of the epoxy resin is 40wt%-60wt%, and the epoxy resin is bisphenol A epoxy resin with an epoxy equivalent weight (EEW) of 185g / eq - 195g / eq, which is used to provide basic bonding strength; the content ratio of the cyanate ester resin is 15wt%-25wt%, and the glass transition temperature (Tg) of the cyanate ester resin is ≥220°C, which improves heat resistance and reduces dielectric loss; the content ratio of the benzoxazine resin is 10wt%-20wt%; the benzoxazine resin can inhibit yellowing at high temperatures and form an interpenetrating network structure with the epoxy resin and cyanate ester resin, which is used to enhance the material stability;

[0008] The nano-functional filler is one of nano-particle materials or nano-fillers; among them:

[0009] When using nano-particle materials, the nano-particle materials at least include surface-modified zinc oxide nano-particles, surface-modified cerium oxide nano-particles, boron nitride nanosheets, and titanium dioxide-coated glass microspheres; the surface-modified zinc oxide nano-particles account for 8wt%-12wt% with a particle size of 20nm - 30nm; the surface-modified cerium oxide nano-particles account for 10wt%-15wt% with a particle size of 3nm - 5nm, and the Ce 3+ / Ce 4+ molar ratio is 51.2∶48.8, which enhances the light reflectivity through the surface plasmon resonance effect. Under the irradiation of light with a wavelength range of 450nm - 650nm, the light reflectivity is ≥92%; the boron nitride nanosheets account for 5wt%-8wt% with a thickness of ≤50nm; the titanium dioxide-coated glass microspheres account for 8wt%-12wt% with a particle size of 1μm - 3μm, which is used to regulate the refractive index to make the refractive index 1.8 - 2.2; the surface-modified zinc oxide nano-particles have a refractive index and can cooperate with the surface-modified cerium oxide nano-particles to enhance the light reflectivity. At the same time, when mixed with the boron nitride nanosheets and titanium dioxide-coated glass microspheres, a reflection-refraction synergistic enhancement system and a heat conduction path can be formed, and the thermal conductivity is ≥3.5W / m·K, which is used to reduce the thermal resistance and inhibit yellowing;

[0010] When using nano-fillers, the nano-fillers at least include CeO2 / TiO2 core-shell particles, boron nitride nanosheets and aluminum oxide (Al2O2); the CeO2 / TiO2 core-shell particles account for 10wt%-20wt%, and the CeO2 / TiO2 core-shell particles are composed of CeO2 with a particle size of 5nm-10nm coated on TiO2 particles with a particle size of 50nm, and the overall particle size is 50nm-60nm. Moreover, the surface of the CeO2 / TiO2 core-shell particles is modified with amino silane, and the reflectivity is >95% in the wavelength range of 450-650nm; aluminum oxide accounts for 10wt%-16wt%, and the aluminum oxide is spherical with a particle size of 50-200nm; boron nitride nanosheets account for 5wt%-8wt%, and the thickness of the boron nitride nanosheets ≤50nm. When jointly constructing a three-dimensional thermal conduction network with spherical aluminum oxide in a mass ratio of 1:2, the thermal conductivity ≥2.5W / m·K;

[0011] The additive system at least includes a curing agent, an accelerator, an anti-aging agent and a coupling agent; the content ratio of the curing agent is 6wt%-14wt%, and the curing agent is selected from amines, modified amines, acid anhydrides or compound curing agents for achieving gradient curing; the content ratio of the accelerator is 0.5wt%-1.5wt%, and the accelerator uses 2-ethyl-4-methylimidazole for accelerating the curing reaction; the content ratio of the anti-aging agent is 0.5-1.3wt%, and the anti-aging agent uses a hindered amine light stabilizer (HALS-622) and a phosphoric acid ester antioxidant (Irganox1010); the content ratio of the coupling agent is 1wt%-3wt%, and the coupling agent uses silane coupling agent KH-560 and silane coupling agent KH-570.

[0012] In the present invention, the resin matrix composed of epoxy resin, cyanate resin and benzoxazine resin provides basic bonding strength, improves heat resistance, reduces dielectric loss, inhibits high-temperature yellowing and enhances material stability; among the nano-functional fillers, when using nano-particle materials, the surface-modified zinc oxide nano-particles and the surface-modified cerium oxide nano-particles synergistically enhance the light reflectivity. At the same time, the surface-modified zinc oxide nano-particles, boron nitride nanosheets and titanium dioxide-coated glass microspheres are mixed to form a reflection-refraction synergistic enhancement system and a thermal conduction path (thermal conductivity ≥3.5W / m·K) for reducing thermal resistance and inhibiting yellowing; when using nano-fillers, the CeO2 / TiO2 core-shell particles, boron nitride nanosheets and aluminum oxide jointly construct a structure with high reflectivity and good thermal conductivity (thermal conductivity ≥2.5W / m·K); in the additive system, the curing agent realizes gradient curing, the accelerator accelerates the curing reaction, the anti-aging agent delays material aging through the synergistic effect of a hindered amine light stabilizer (HALS-622) and a phosphoric acid ester antioxidant (Irganox1010); the coupling agents silane coupling agent KH-560 and KH-570 enhance the interfacial bonding between the filler and the resin;

[0013] In addition, when using nanoparticle materials, the coupling agents on the surfaces of surface-modified zinc oxide nanoparticles and surface-modified cerium oxide nanoparticles react with each other and with the resin matrix to form stable connections; the curing agent reacts with the active groups of the resin matrix to achieve crosslinking and curing. Taking the reaction between surface-modified zinc oxide nanoparticles (with KH-570 as the surface coupling agent) and surface-modified cerium oxide nanoparticles (with KH-560 as the surface coupling agent) as an example, the chemical reaction formula is as follows:

[0014] 1. Reaction between surface-modified zinc oxide nanoparticles and surface-modified cerium oxide nanoparticles:

[0015] The active group of the silane coupling agent KH-570 on the surface of the surface-modified zinc oxide nanoparticles is CH2=CHSi(OCH3)3, and the active group generated after hydrolysis of the silane coupling agent KH-560 on the surface of the surface-modified cerium oxide nanoparticles is HO-Si(CH2CH2OH)3. Then the reaction between them is:

[0016] CH2=CHSi(OCH3)3+HO-Si(CH2CH2OH)3→CH2=CHSi-O-Si(CH2CH2OH)3+CH3OH

[0017] , which makes the surface-modified zinc oxide nanoparticles and surface-modified cerium oxide nanoparticles connected together by siloxane bonds, enhancing the binding force between the two and facilitating the synergistic improvement of the light reflectivity;

[0018] 2. Reaction between surface-modified zinc oxide nanoparticles and the resin matrix:

[0019] Taking epoxy resin (containing epoxy group -CH(O)CH2-) as an example, the silanol group -SiOH generated after hydrolysis of the silane coupling agent KH-570 on the surface of the surface-modified zinc oxide nanoparticles can react with the epoxy group of the epoxy resin. Then the reaction is:

[0020] HO-Si(CH2CH3)3+-CH(O)CH2-→-CH(OSi(CH2CH3)3)CH2-+H2O, which makes the surface-modified zinc oxide nanoparticles firmly bind to the resin matrix, enhancing the interfacial bonding between the nano-filler and the resin matrix and improving the overall performance of the material;

[0021] 3. Reaction between surface-modified cerium oxide nanoparticles and the resin matrix:

[0022] Taking epoxy resin as an example, the silanol group -SiOH generated after hydrolysis of the silane coupling agent KH-560 on the surface of the surface-modified cerium oxide nanoparticles reacts with the epoxy group of the epoxy resin:

[0023] HO-Si(CH2CH2OH)3+-CH(O)CH2-→-CH(OSi(CH2CH2OH)3)CH2-+H2O, surface

[0024] The surface-modified cerium oxide nanoparticles also form a stable connection with the resin matrix, which helps to construct a stable reflection-refraction synergistic enhancement system and improve the stability of the material.

[0025] Second, according to Figure 1 As shown, the present invention provides a preparation process of a reflective die attach adhesive material based on nanoparticle dispersion technology, including the following steps:

[0026] When used for LED brackets:

[0027] S1. Surface treatment of nanoparticles: Put the surface-modified cerium oxide nanoparticles into a 3wt% ethanol solution of silane coupling agent KH-560 (the ethanol solution should be able to completely cover and immerse the surface-modified cerium oxide nanoparticles), and ultrasonically treat for 30 min to make the silane coupling agent modify its surface. Then, vacuum dry at 60°C to obtain hydrophobic modified cerium oxide nanoparticles. At the same time, put the surface-modified zinc oxide nanoparticles into a 3wt% ethanol solution of silane coupling agent KH-570 (the ethanol solution should be able to completely cover and immerse the surface-modified zinc oxide nanoparticles), ultrasonically treat for 30 min, and then vacuum dry at 60°C to obtain zinc oxide nanoparticles;

[0028] S2. Preparation of pre-dispersion system: Prepare xylene and methyl ethyl ketone, and mix them in a volume ratio of 3:1 using an electric stirrer to obtain a mixed solvent. Then, add the surface-treated modified cerium oxide nanoparticles, surface-modified zinc oxide nanoparticles, boron nitride nanosheets, and titanium dioxide-coated glass microspheres to the mixed solvent, and disperse them at a speed of 8000 rpm for 45 min using a high-speed shear disperser to fully disperse each nano-functional filler and form a homogeneous pre-dispersion slurry;

[0029] S3. Resin mixing and defoaming: Place epoxy resin, cyanate ester resin, and benzoxazine resin in a closed container equipped with stirring and heating functions, and continuously stir at a stirring speed of 500 rpm at 80°C for 1 h for melt blending to form a uniform molten mixture. Then, add the pre-dispersion slurry, as well as a curing agent, a promoter, and an anti-aging agent to the molten mixture. At this time, place it in a vacuum environment with a vacuum degree ≤ -0.095 MPa, and stir and defoam at a stirring speed of 500 rpm for 2 h to remove the bubbles in the system;

[0030] S4. Solidification and Molding: Coat the defoamed die attach glue material onto the LED bracket and adopt a stepwise curing process. The stepwise curing process includes: in the first stage, raise the temperature to 120 °C and maintain it for 1 h for pre-curing to form a preliminary three-dimensional network structure; in the second stage, raise the temperature to 150 °C and maintain it for 2 h to fully crosslink the resin and form a stable solid structure; for post-curing, raise the temperature to 220 °C and maintain it for 1 h to improve the heat resistance and stability of the die attach glue. Finally, obtain a reflective die attach glue material for LED bracket encapsulation.

[0031] Thirdly, according to Figure 2 as shown, the present invention provides a preparation process of a reflective die attach glue material based on nanoparticle dispersion technology, which further includes the following steps:

[0032] When used for an LED chip substrate:

[0033] S2.1. Nanofiller Pretreatment: Mix CeO2 / TiO2 core-shell particles and KH-560 coupling agent in a ratio of 10:1, and ultrasonically disperse them at a temperature of 60 °C for 30 min to form an activated filler slurry. At the same time, put boron nitride and aluminum oxide (Al2O2) into a ball mill and mix them at a rotation speed of 300 rpm for 2 h to obtain a uniform thermal conductive filler.

[0034] S2.2. Resin Matrix Premixing: Place the resin matrix in a vacuum stirring kettle, mix it at a temperature of 80 °C and a rotation speed of 500 rpm for 1 h, add a curing agent, a promoter, a yellowing resistance agent, and an anti-aging agent, and continue stirring for 30 min to obtain a uniformly mixed resin matrix slurry.

[0035] S2.3. Filler Dispersion: Add the activated filler slurry and the thermal conductive filler to the resin matrix slurry. First, use a high-speed shear disperser to disperse them at a rotation speed of 12000 rpm for 1 h, and then use a three-roll grinder for 3 grinding operations, and set the gap between adjacent rollers of the three-roll grinder to 10 μm. Then, under the conditions of a vacuum degree of -0.1 MPa and a temperature of 40 °C, perform vacuum defoaming for 30 min to remove the bubbles in the system and obtain a uniform die attach glue slurry.

[0036] S2.4. Solidification and Molding: Coat the defoamed die attach glue slurry onto the LED chip substrate and adopt stepwise curing. The stepwise curing includes: in the first stage, raise the temperature to 100 °C and maintain it for 1 h (pre-curing) to start crosslinking the resin and form a preliminary three-dimensional network structure; in the second stage, raise the temperature to 150 °C and maintain it for 2 h (complete curing) to fully crosslink the resin and form a stable and well-performing solid structure, and finally obtain a reflective die attach glue material for LED chip substrate encapsulation.

[0037] Fourthly, the present invention provides a reflective die bonding glue material based on nanoparticle dispersion technology for the bracket encapsulation of LEDs and the chip substrate encapsulation of LEDs, and the power of the LEDs is 2W - 8W.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] 1. In the reflective die bonding glue material, preparation process and application based on nanoparticle dispersion technology, through the synergistic effect of surface-modified zinc oxide nanoparticles and surface-modified cerium oxide nanoparticles, combined with the total reflection characteristics of titanium dioxide-coated glass microspheres, an efficient reflection-refraction synergistic enhancement system is constructed; the surface plasmon resonance effect of surface-modified cerium oxide nanoparticles, combined with zinc oxide nanoparticles with a high refractive index, improves the initial luminous flux of the LEDs, which is increased by 18% - 22% compared with traditional die bonding glue, and the light utilization rate is increased by 20% - 25%, tapping the potential of six-sided light emission of the chip, thereby improving the quality of the die bonding glue.

[0040] 2. In the reflective die bonding glue material, preparation process and application based on nanoparticle dispersion technology, through the oriented arrangement of boron nitride nanosheets to form an efficient heat conduction channel, the thermal resistance is reduced by 35%, which can quickly conduct a large amount of heat generated by the LEDs. Benzoxazine resin effectively inhibits high-temperature yellowing, and hindered amine light stabilizers and phosphate antioxidants synergistically play an anti-aging role, so that the light transmittance attenuation of the die bonding glue after 3000h of aging is controlled at ≤5%, and the bonding strength retention rate after 1000h of high-temperature and high-humidity testing is greater than 90%, thereby improving the stability of LED light emission and the long service life.

[0041] 3. In the reflective die bonding glue material, preparation process and application based on nanoparticle dispersion technology, through two-step dispersion operations of high-speed shear dispersion and three-roll grinding, the uniform dispersion of nano-fillers in the die bonding glue is achieved, effectively avoiding the agglomeration phenomenon of nanoparticles, increasing the uniformity and stability of material properties. At the same time, the gradient curing process adjusts the temperature according to different stages, enabling the resin to gradually complete cross-linking, not only avoiding the generation of internal stress and cracking problems, but also improving the structural strength and stability of the die bonding glue. Description of the Drawings

[0042] Figure 1 It is a process flow block diagram of the preparation of the reflective die bonding glue material for the bracket encapsulation of LEDs according to the present invention;

[0043] Figure 2 It is a process flow block diagram of the preparation of the reflective die bonding glue material for the chip substrate encapsulation of LEDs according to the present invention. Detailed Embodiments

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0045] Example 1: Preparation of a reflective die bonding adhesive material and performance test of an LED with a power of 0W - 1W

[0046] Preparation method:

[0047] Surface treatment of nanoparticles: Put the surface-modified cerium oxide nanoparticles into a 3wt% ethanol solution of silane coupling agent KH-560, ultrasonically treat for 30 min, and vacuum dry at 60°C to obtain hydrophobic modified cerium oxide nanoparticles; at the same time, place the surface-modified zinc oxide nanoparticles in a 3wt% ethanol solution of silane coupling agent KH-570, ultrasonically treat for 30 min, and then vacuum dry at 60°C to obtain zinc oxide nanoparticles.

[0048] Preparation of the pre-dispersion system: Use an electric stirrer to mix xylene and butanone in a volume ratio of 3:1 to form a solvent, add the surface-treated modified cerium oxide nanoparticles, surface-modified zinc oxide nanoparticles, boron nitride nanosheets, and titanium dioxide-coated glass microspheres to the mixed solvent, and disperse at a speed of 8000 rpm for 45 min using a high-speed shear disperser to form a homogeneous pre-dispersion slurry.

[0049] Resin mixing and defoaming: Place epoxy resin (40wt%), cyanate resin (15wt%), and benzoxazine resin (10wt%) in a closed container equipped with stirring and heating functions, continuously stir at 80°C at a stirring speed of 500 rpm for 1 h for melt blending, add the pre-dispersion slurry, as well as a curing agent (amine curing agent, 8wt%), an accelerator (2-ethyl-4-methylimidazole, 0.5wt%), and an anti-aging agent (hindered amine light stabilizer HALS-622, 0.3wt%; phosphite antioxidant Irganox1010, 0.2wt%) to the molten mixture, and stir and defoam at a stirring speed of 500 rpm for 2 h in an environment with a vacuum degree ≤ -0.095 MPa.

[0050] Curing and forming: Coat the defoamed die bonding adhesive material on the LED bracket and adopt a stepwise curing process. The first stage is pre-cured at 120°C for 1 h, the second stage is fully cross-linked at 150°C for 2 h, and the post-curing is carried out at 220°C for 1 h to improve heat resistance, obtaining a reflective die bonding adhesive material.

[0051] Performance test method:

[0052] Luminous flux test: Place the 0W - 1W LED device encapsulated with this die bonding glue material in an integrating sphere, and use a luminous flux tester to measure its initial luminous flux. The initial luminous flux has increased by 10%;

[0053] Thermal resistance test: Use a thermal resistance tester to measure the thermal resistance of the LED device. The thermal resistance has decreased by 20%, showing a certain heat dissipation effect;

[0054] Yellowing and light transmittance test: After aging the LED device in a high - temperature (such as 80 °C) environment for 1000 h, use a spectrophotometer to measure the attenuation of its light transmittance; the light transmittance has attenuated by 8% after 3000 h of aging;

[0055] Bonding strength test: Use a tensile testing machine to conduct a bonding strength test on the encapsulated LED bracket. The bonding strength retention rate is 85%.

[0056] Example 2: Preparation of a reflective die bonding glue material and performance test of LEDs with a power of 2W - 8W

[0057] Preparation method:

[0058] Surface treatment of nanoparticles: The same as in Example 1;

[0059] Preparation of the pre - dispersion system: The same as in Example 1;

[0060] Resin mixing and degassing: Place epoxy resin (50 wt%), cyanate resin (20 wt%), and benzoxazine resin (15 wt%) in a sealed container equipped with stirring and heating functions. Continuously stir and melt - blend at 80 °C with a stirring speed of 500 rpm for 1 h. Add the pre - dispersion slurry, as well as a curing agent (compound curing agent, 10 wt%), an accelerator (2 - ethyl - 4 - methylimidazole, 1 wt%), and an anti - aging agent (hindered amine light stabilizer HALS - 622, 0.5 wt%; phosphite antioxidant Irganox1010, 0.3 wt%) to the molten mixture. Stir and degas at a stirring speed of 500 rpm for 2 h in an environment with a vacuum degree ≤ - 0.095 MPa;

[0061] Curing and molding: The same as in Example 1.

[0062] Performance test method:

[0063] Luminous flux test: Place the 2W - 8W LED device encapsulated with this die bonding glue material in an integrating sphere, and use a luminous flux tester to measure its initial luminous flux. The initial luminous flux has increased by 20%, and the light utilization rate has increased by 23%, effectively tapping the six - sided light - emitting potential of the chip;

[0064] Thermal resistance test: Use a thermal resistance tester to measure the thermal resistance of the LED device. The thermal resistance has decreased by 35%, and it can quickly conduct the heat generated by the LED;

[0065] Yellowing and light transmittance test: After aging the LED device in a high-temperature environment (such as 80 °C) for 1000 h, use a spectrophotometer to measure the attenuation of its light transmittance; after 3000 h of aging, the light transmittance attenuates by 4%;

[0066] Bonding strength test: Use a tensile testing machine to conduct a bonding strength test on the packaged LED bracket. After 1000 h of high-temperature and high-humidity test, the bonding strength retention rate is 93%.

[0067] Example 3: Preparation of a reflective die-bonding adhesive material and performance test of an LED with a power above 8 W

[0068] Preparation method:

[0069] Surface treatment of nanoparticles: The same as in Example 1;

[0070] Preparation of the pre-dispersion system: The same as in Example 1;

[0071] Resin mixing and degassing: Place epoxy resin (60 wt%), cyanate resin (25 wt%), and benzoxazine resin (20 wt%) in a sealed container equipped with stirring and heating functions. Continuously stir and melt-blend at 80 °C for 1 h at a stirring speed of 500 rpm. Add the pre-dispersed slurry, as well as a curing agent (anhydride curing agent, 12 wt%), an accelerator (2-ethyl-4-methylimidazole, 1.5 wt%), and an anti-aging agent (hindered amine light stabilizer HALS-622, 0.8 wt%; phosphite antioxidant Irganox1010, 0.5 wt%) to the molten mixture. Stir and degas at a stirring speed of 500 rpm for 2 h in an environment with a vacuum degree ≤ -0.095 MPa;

[0072] Curing and molding: The same as in Example 1.

[0073] Performance test method:

[0074] Luminous flux test: Place an LED device with a power above 8 W encapsulated with this die-bonding adhesive material in an integrating sphere, and use a luminous flux tester to measure its initial luminous flux. The initial luminous flux has increased by 15%;

[0075] Thermal resistance test: Use a thermal resistance tester to measure the thermal resistance of the LED device. The thermal resistance has decreased by 30%;

[0076] Yellowing and light transmittance test: After aging the LED device in a high-temperature environment (such as 80 °C) for 1000 h, use a spectrophotometer to measure the attenuation of its light transmittance; after 3000 h of aging, the light transmittance attenuates by 6%;

[0077] Bond strength test: Use a tensile testing machine to conduct a bond strength test on the packaged LED bracket. The bond strength retention rate is 90% after 1000h of high-temperature and high-humidity testing.

[0078] Comparative Example 1: Performance test of traditional light-transmitting die-bonding glue

[0079] Preparation method:

[0080] Use the traditional method to prepare light-transmitting die-bonding glue. The main components only contain materials that improve light transmittance (such as pure SiO2 for antireflection), and there is no reflective filler.

[0081] Performance test method:

[0082] Luminous flux test: Place the 2W - 8W LED device encapsulated with light-transmitting die-bonding glue in an integrating sphere, and use a luminous flux tester to measure its initial luminous flux, with an initial luminous flux of 2%;

[0083] Thermal resistance test: Use a thermal resistance tester to measure the thermal resistance of the LED device, and the thermal resistance decreases by -10%;

[0084] Yellowing and light transmittance test: After aging the LED device in a high-temperature environment (such as 80°C) for 1000h, use a spectrophotometer to measure the attenuation of its light transmittance; the light transmittance attenuation is 20% after 3000h of aging;

[0085] Bond strength test: Use a tensile testing machine to conduct a bond strength test on the packaged LED bracket. The bond strength retention rate is 75% after 1000h of high-temperature and high-humidity testing.

[0086] Table 1 Performance test results of Examples 1 - 3 and Comparative Example 1

[0087]

[0088] It can be seen from the comparison between Examples 1-3 and Comparative Example 1 that in LED application scenarios with different powers, the silver paste materials of the present invention all have good improvement effects. They can not only increase the initial luminous flux, reduce the thermal resistance, but also effectively inhibit yellowing and maintain a high bonding strength. Especially in Example 2, for LEDs with a power of 2W-8W, the initial luminous flux is increased by 20%, the light utilization rate is increased by 23%, the thermal resistance is reduced by 35%, the light transmittance attenuation after 3000h of aging is only 4%, and the bonding strength retention rate reaches 93% after 1000h of high-temperature and high-humidity testing. It can be seen that in the material system of the present invention, the resin matrix provides basic properties. The surface-modified zinc oxide nanoparticles and surface-modified cerium oxide nanoparticles in the nano-functional fillers synergistically enhance light reflection, and combined with titanium dioxide-coated glass microspheres to construct an efficient reflection-refraction system to increase the luminous flux; boron nitride nanosheets form a heat conduction path, combined with benzoxazine resin and anti-aging agents to reduce the thermal resistance and inhibit yellowing; in the preparation process, high-speed shear dispersion and three-roll grinding ensure the uniform dispersion of nano-fillers and avoid agglomeration; the gradient curing process enables the resin to crosslink gradually, avoiding internal stress and cracking and improving the structural strength.

[0089] Example 4: Preparation of the reflective silver paste material, different parameters and performance detection of the LED chip substrate encapsulation Preparation method:

[0090] Pretreatment of nano-fillers: Mix CeO2 / TiO2 core-shell particles with KH-560 coupling agent at a ratio of 10:1, and ultrasonically disperse for 30 min at a temperature of ℃ to form an activated filler slurry; at the same time, put boron nitride and aluminum trioxide (spherical, particle size 50 nm) into a ball mill and mix at a speed of 300 rpm for 2 h to obtain a uniform heat-conducting filler;

[0091] Premixing of resin matrix: Put epoxy resin (45 wt%), cyanate resin (20 wt%), and benzoxazine resin (12 wt%) into a vacuum stirring kettle, mix at a temperature of 80 °C and a speed of 500 rpm for 1 h, add a curing agent (compound curing agent, 11 wt%), a promoter (2-ethyl-4-methylimidazole, 1.2 wt%), a yellowing inhibitor (UV-531, 1 wt%), and an anti-aging agent (hindered amine light stabilizer HALS-622, 0.6 wt%; phosphite antioxidant Irganox1010, 0.4 wt%), and continue to stir for 30 min to obtain a uniformly mixed resin matrix slurry;

[0092] Filler dispersion: The activated filler slurry and the thermal conductive filler are added to the resin matrix slurry. First, a high-speed shear disperser is used to disperse at a speed of 12,000 rpm for 1 h, and then a three-roll grinder is used for 3 grinding operations. The gap between adjacent rollers of the three-roll grinder is set to 10 μm. Then, under the conditions of a vacuum degree of -0.1 MPa and a temperature of 40 °C, vacuum degassing is carried out for 30 min to remove the bubbles in the system, and a uniform die attach paste slurry is obtained.

[0093] Curing and forming: The degassed die attach paste slurry is coated on the LED chip substrate, and step curing is adopted. Step curing includes a first stage of raising the temperature to 100 °C and holding for 1 h (pre-curing), so that the resin starts to crosslink and form a preliminary three-dimensional network structure; a second stage of raising the temperature to 150 °C and holding for 2 h (complete curing), so that the resin is completely crosslinked to form a stable and good-performance solid state structure, and finally a reflective die attach paste material for LED chip substrate packaging is obtained.

[0094] Performance test method:

[0095] Luminous flux test: After assembling the LED chip substrate encapsulated with this die attach paste material into an LED device, it is placed in an integrating sphere, and a luminous flux tester is used to measure its initial luminous flux, and the initial luminous flux is increased by 18%.

[0096] Thermal resistance test: A thermal resistance tester is used to measure the thermal resistance of the LED device, and the thermal resistance is reduced by 30%.

[0097] Yellowing and transmittance test: After aging the LED device in a high-temperature (such as 80 °C) environment for 3000 h, a spectrophotometer is used to measure the transmittance attenuation, and the transmittance attenuation is 5%.

[0098] Bonding strength test: A tensile testing machine is used to test the bonding strength of the encapsulated LED chip substrate. After 1000 h of high-temperature and high-humidity test, the bonding strength retention rate is 92%.

[0099] Example 5: Preparation of different parameters of the reflective die attach paste material and performance detection for LED chip substrate packaging Preparation method:

[0100] Nanofiller pretreatment: The same as in Example 4;

[0101] Resin matrix premixing: Epoxy resin (55 wt%), cyanate resin (18 wt%), and benzoxazine resin (18 wt%) were placed in a vacuum stirring kettle and mixed for 1 h at a temperature of 80 °C and a rotation speed of 500 rpm. Then, a curing agent (amine curing agent, 13 wt%), an accelerator (2-ethyl-4-methylimidazole, 1.3 wt%), a yellowing resistance agent (UV-531, 1.5 wt%), and an anti-aging agent (hindered amine light stabilizer HALS-622, 0.7 wt%; phosphate antioxidant Irganox1010, 0.45 wt%) were added, and stirring was continued for 30 min to obtain a uniformly mixed resin matrix slurry.

[0102] Filler dispersion: The same as in Example 4;

[0103] Curing and molding: The same as in Example 4.

[0104] Performance test method:

[0105] Luminous flux test: The same as in Example 4, and the initial luminous flux increased by 21%.

[0106] Thermal resistance test: The same as in Example 4, and the thermal resistance decreased by 32%.

[0107] Yellowing and light transmittance test: The same as in Example 4, and the light transmittance decreased by 4.5%.

[0108] Bonding strength test: The same as in Example 4, and the bonding strength retention rate was 94%.

[0109] Comparative Example 2: Preparation parameters of die attach glue material and performance detection for LED chip substrate packaging

[0110] Preparation method:

[0111] The common preparation method of die attach glue material in the prior art was adopted. The main components only contained materials for improving light transmittance (such as pure SiO2 for antireflection), without reflective fillers, and the nano-particle dispersion technology, specific resin matrix, and additive system of the present invention were not used.

[0112] Performance test method:

[0113] Luminous flux test: The same as in Example 4, and the initial luminous flux increased by 5%;

[0114] Thermal resistance test: The same as in Example 4, and the thermal resistance decreased by 5%;

[0115] Yellowing and light transmittance test: The same as in Example 4, and the light transmittance decreased by 18%;

[0116] Bonding strength test: The same as in Example 4, and the bonding strength retention rate was 78%.

[0117] Comparative Example 3: Preparation of Different Parameters of Reflective Die Bonding Adhesive Material and Performance Detection of LED Chip Substrate Encapsulation

[0118] The preparation steps are the same as those in Example 4, but the content of epoxy resin is increased to 65 wt%, the content of curing agent is increased to 16 wt%, and the proportions of other components are adjusted accordingly to ensure that the total mass fraction is 100%.

[0119] Performance testing method:

[0120] Luminous flux test: The same as in Example 4, and the initial luminous flux is increased by 13%;

[0121] Thermal resistance test: The same as in Example 4, and the thermal resistance is reduced by 25%;

[0122] Yellowing and light transmittance test: The same as in Example 4, and the light transmittance decays by 7%;

[0123] Bonding strength test: The same as in Example 4, and the bonding strength retention rate is 88%.

[0124] Comparative Example 3: Preparation of Different Parameters of Reflective Die Bonding Adhesive Material and Performance Detection of LED Chip Substrate Encapsulation

[0125] The preparation steps are the same as those in Example 4, but the content of epoxy resin is reduced to 35 wt%, the content of curing agent is reduced to 4 wt%, and the proportions of other components are adjusted accordingly to ensure that the total mass fraction is 100.

[0126] Performance testing method:

[0127] Luminous flux test: The same as in Example 4, and the initial luminous flux is increased by 11%;

[0128] Thermal resistance test: The same as in Example 4, and the thermal resistance is reduced by 18%;

[0129] Yellowing and light transmittance test: The same as in Example 4, and the light transmittance decays by 10%;

[0130] Bonding strength test: The same as in Example 4, and the bonding strength retention rate is 80%.

[0131] Table 2 shows the performance test results of Examples 4 - 5 and Comparative Examples 2 - 4

[0132]

[0133]

[0134] It can be seen from the comparison between Examples 4 - 5 and Comparative Examples 2 - 4 that in the case of being used for the encapsulation of LED chip substrates, the reflective die - bonding glue material of the present invention has good effects; compared with the ordinary die - bonding glue material in Comparative Example 2, through the material system and preparation process, the performance after the encapsulation of the LED chip substrate is improved in the present invention; in Examples 4 and 5, the improvement amplitudes of the initial luminous flux are 18% and 21% respectively, which are much higher than 5% in Comparative Example 2, indicating that the present invention can effectively tap the luminous potential of the chip and improve the luminous flux; the reduction amplitudes of the thermal resistance are also significantly larger, reaching 30% and 32% respectively, while only 5% in Comparative Example 2, showing that the present invention has better thermal conductivity and can quickly conduct the heat generated by the LED; in terms of yellowing resistance and bonding strength, the light transmittance attenuation of Examples 4 and 5 after aging is lower, being 5% and 4.5% respectively, and the bonding strength retention rate is higher, being 92% and 94% respectively, while the light transmittance attenuation of Comparative Example 2 reaches 18%, and the bonding strength retention rate is only 78%, reflecting the good anti - aging performance and high bonding stability of the present invention; especially in Example 5, the initial luminous flux is increased by 21%, the thermal resistance is reduced by 32%, the light transmittance attenuation after aging is only 4.5%, and the bonding strength retention rate is as high as 94%.

[0135] It can be seen that the present invention constructs a structure with high reflectivity and good thermal conductivity through CeO2 / TiO2 core - shell particles, boron nitride nanosheets and aluminum oxide; the high reflectivity of CeO2 / TiO2 core - shell particles improves the luminous flux, the boron nitride nanosheets and aluminum oxide form a thermal conduction network to reduce the thermal resistance, can also inhibit yellowing, enhance the material stability, and effectively solve the problems such as light and heat of the traditional die - bonding glue, and improve the comprehensive performance of the LED device.

[0136] Example 6: Detection of different parameters of the reflective die - bonding glue material and its performance for the encapsulation of LED brackets

[0137] Preparation method:

[0138] Surface treatment of nanoparticles: the same as in Example 1;

[0139] Preparation of the pre - dispersion system: the same as in Example 1;

[0140] Resin mixing and degassing: Put epoxy resin (40 wt%), cyanate resin (25 wt%), and benzoxazine resin (12 wt%) into a sealed container equipped with stirring and heating functions. Continuously stir at a stirring speed of 500 rpm for 1 h at 80 °C for melt blending. Add the pre-dispersed slurry, as well as a curing agent (compound curing agent, 12 wt%), an accelerator (2-ethyl-4-methylimidazole, 1.2 wt%), and an anti-aging agent (hindered amine light stabilizer HALS-622, 0.7 wt%; phosphite antioxidant Irganox1010, 0.4 wt%) to the molten mixture. Stir and degas at a stirring speed of 500 rpm for 2 h in an environment with a vacuum degree ≤ -0.095 MPa;

[0141] Curing and molding: The same as in Example 1.

[0142] Performance testing method:

[0143] The same as in Example 1.

[0144] Example 7: Different parameters of the reflective die bonding glue material and performance detection for LED bracket encapsulation

[0145] Surface treatment of nanoparticles: The same as in Example 1;

[0146] Preparation of the pre-dispersed system: The same as in Example 1;

[0147] Resin mixing and degassing: Put epoxy resin (55 wt%), cyanate resin (15 wt%), and benzoxazine resin (18 wt%) into a sealed container equipped with stirring and heating functions. Continuously stir at a stirring speed of 500 rpm for 1 h at 80 °C for melt blending. Add the pre-dispersed slurry, as well as a curing agent (compound curing agent, 10 wt%), an accelerator (2-ethyl-4-methylimidazole, 1.0 wt%), and an anti-aging agent (hindered amine light stabilizer HALS-622, 0.6 wt%; phosphite antioxidant Irganox1010, 0.35 wt%) to the molten mixture. Stir and degas at a stirring speed of 500 rpm for 2 h in an environment with a vacuum degree ≤ -0.095 MPa;

[0148] Curing and molding: The same as in Example 1.

[0149] Performance testing method:

[0150] The same as in Example 1.

[0151] Comparative Example 5: Preparation parameters of the die bonding glue material and performance detection for LED bracket encapsulation

[0152] Preparation method:

[0153] The traditional method is used to prepare the light-transmitting die bonding glue. The main components only contain materials that improve the light transmittance (such as pure SiO2 for antireflection), without reflective fillers; and in the preparation process, the nano-particle dispersion technology, specific resin matrix and additive system of the present invention are not adopted; the specific steps are as follows: the main light-transmitting materials are simply mixed with conventional curing agents, accelerators, etc., stirred evenly at a certain temperature and then coated on the LED bracket, and cured and formed under conventional conditions.

[0154] Performance test method:

[0155] The same as that of Example 1.

[0156] Comparative Example 6: Different parameters of the reflective die bonding glue material and performance detection for LED bracket packaging

[0157] Preparation method:

[0158] The preparation steps are the same as those of Example 6, but the content of surface-modified zinc oxide nanoparticles is reduced to 5wt%, and the content of surface-modified cerium oxide nanoparticles is increased to 18wt%, and the proportions of other components are adjusted accordingly to ensure that the total mass fraction is 100%.

[0159] Performance test method:

[0160] The same as that of Example 1.

[0161] Comparative Example 7: Different parameters of the reflective die bonding glue material and performance detection for LED bracket packaging

[0162] Preparation method:

[0163] The preparation steps are the same as those of Example 6, but the content of boron nitride nanosheets is reduced to 3wt%, and the content of titanium dioxide-coated glass microspheres is increased to 15wt%, and the proportions of other components are adjusted accordingly to ensure that the total mass fraction is 100%.

[0164] Performance test method:

[0165] The same as that of Example 1.

[0166] Table 3 shows the performance test results of Examples 6-7 and Comparative Examples 5-7

[0167]

[0168]

[0169] It can be seen from the comparison between Examples 6-7 and Comparative Examples 5-7 that, in the case of being used for LED bracket encapsulation, the reflective die bonding glue material of the present invention still has good effects; compared with the traditional light-transmitting die bonding glue material in Comparative Example 5, the present invention improves the performance after LED bracket encapsulation through a unique material system and preparation process; in Examples 6 and 7, the improvement amplitudes of the initial luminous flux are 16% and 19% respectively, which are much higher than 3% of Comparative Example 5, indicating that the present invention can more effectively tap the light-emitting potential of the chip and improve the luminous flux; the reduction amplitudes of the thermal resistance are also significantly larger, reaching 30% and 33% respectively, while Comparative Example 5 only reduces by 8%, showing that the present invention has better thermal conductivity and can better conduct the heat generated by the LED; in terms of yellowing resistance and bonding strength, the light transmittance attenuation of Examples 6 and 7 after aging is lower, being 5.5% and 4.8% respectively, and the bonding strength retention rates are higher, being 90% and 92% respectively, while the light transmittance attenuation of Comparative Example 5 reaches 16% and the bonding strength retention rate is only 72%, reflecting the good anti-aging performance and high bonding stability of the present invention; in Comparative Examples 6 and 7, due to the change in the content of some nano-functional fillers, the performance fluctuates, but it is still better than that of Comparative Example 5 on the whole, further illustrating the importance of the synergistic effect among the components in the material system of the present invention.

[0170] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A reflective die bonding adhesive material based on nanoparticle dispersion technology, characterized in that, It includes a resin matrix, nano-functional fillers, and an additive system, where: The resin matrix at least includes epoxy resin, cyanate ester resin, and benzoxazine resin; the benzoxazine resin can inhibit yellowing at high temperatures and form an interpenetrating network structure with epoxy resin and cyanate ester resin to enhance the material stability; The nano-functional fillers are one of nano-particle materials or nano-fillers; where: The nano-particle materials at least include surface-modified zinc oxide nano-particles, surface-modified cerium oxide nano-particles, boron nitride nanosheets, and titanium dioxide-coated glass microspheres; the surface-modified zinc oxide nano-particles and surface-modified cerium oxide nano-particles synergistically enhance the light reflectivity. At the same time, they are mixed with boron nitride nanosheets and titanium dioxide-coated glass microspheres to form a reflection-refraction synergistic enhancement system and a heat conduction path to reduce the thermal resistance and inhibit yellowing; The nano-fillers at least include CeO2 / TiO2 core-shell particles, boron nitride nanosheets, and aluminum oxide; The additive system at least includes a curing agent, an accelerator, an anti-aging agent, and a coupling agent.

2. The reflective die bonding glue material based on nanoparticle dispersion technology according to claim 1, characterized in that In the resin matrix: the content ratio of epoxy resin is 40wt%-60wt%; the cyanate ester resin accounts for 15wt%-25wt%; the benzoxazine resin accounts for 10wt%-20wt%; When the nano-functional fillers are nano-particle materials, the surface-modified zinc oxide nano-particles account for 8wt%-12wt%; The surface-modified cerium oxide nano-particles account for 10wt%-15wt%; the boron nitride nanosheets account for 5wt%-8wt%; the titanium dioxide-coated glass microspheres account for 8wt%-12wt%; when the nano-functional fillers are nano-fillers, the CeO2 / TiO2 core-shell particles account for 10wt%-20wt%; the boron nitride nanosheets account for 5wt%-8wt%; the aluminum oxide accounts for 10wt%-16wt%; In the additive system: the curing agent accounts for 6wt%-14wt%; the accelerator accounts for 0.5wt%-1.5wt%; the anti-aging agent accounts for 0.5 - 1.3wt%; the coupling agent accounts for 1wt%-3wt%.

3. The reflective die bonding adhesive material based on nanoparticle dispersion technology according to claim 1, characterized in that The epoxy resin used is bisphenol A type epoxy resin with an epoxy equivalent of 185g / eq - 195g / eq; the glass transition temperature of the cyanate ester resin is ≥220°C.

4. The reflective die-bonding adhesive material based on nanoparticle dispersion technology according to claim 2, characterized in that, The particle size of the surface-modified zinc oxide nanoparticles is 20 nm - 30 nm; the particle size of the surface-modified cerium oxide nanoparticles is 3 nm - 5 nm, and the Ce 3+ / Ce 4+ molar ratio is 51.2:48.8; the thickness of the boron nitride nanosheets is ≤ 50 nm; the particle size of the titanium dioxide-coated glass microspheres is 1 μm - 3 μm, and they are used to regulate the refractive index to 1.8 - 2.

2.

5. The reflective die bonding glue material based on nanoparticle dispersion technology according to claim 1, wherein When the nano-functional fillers are nano-fillers, the CeO2 / TiO2 core-shell particles are composed of CeO2 with a particle size of 5nm - 10nm coated on TiO2 particles with a particle size of 50nm, and the overall particle size is 50nm - 60nm. And the surface of the CeO2 / TiO2 core-shell particles is modified with amino silane; the aluminum oxide is spherical with a particle size of 50 - 200nm; the thickness of the boron nitride nanosheets is ≤50nm, and they jointly construct a three-dimensional heat conduction network with spherical aluminum oxide in a mass ratio of 1:

2.

6. The reflective die bonding adhesive material based on nanoparticle dispersion technology according to claim 1, wherein The curing agent is selected from amines, modified amines, acid anhydrides, or compounded curing agents; the accelerator used is 2-ethyl-4-methylimidazole; the anti-aging agent used is a hindered amine light stabilizer and a phosphate antioxidant; the coupling agent used is silane coupling agent KH-560 and silane coupling agent KH-570.

7. The reflective die bonding glue material based on nanoparticle dispersion technology according to claim 6, characterized in that The content proportion of the hindered amine light stabilizer is 0.3 wt% - 0.8 wt%; the content proportion of the phosphoric acid ester antioxidant is 0.2 wt% - 0.5 wt%.

8. The preparation process of the reflective die bonding glue material based on the nanoparticle dispersion technology according to any one of claims 1-7, characterized in that, It includes the following steps: S1.

1. Surface treatment of nanoparticles: Put the surface-modified cerium oxide nanoparticles into an ethanol solution of silane coupling agent KH-560 for ultrasonic treatment, and then vacuum dry at 55°C - 65°C to obtain hydrophobic modified cerium oxide nanoparticles. At the same time, put the surface-modified zinc oxide nanoparticles into an ethanol solution of silane coupling agent KH-570 for ultrasonic treatment and then vacuum dry to obtain zinc oxide nanoparticles; S1.

2. Preparation of pre-dispersion system: Mix xylene and butanone in a volume ratio of 3:1 with an electric stirrer to obtain a mixed solvent. Then add the surface-treated modified cerium oxide nanoparticles, surface-modified zinc oxide nanoparticles, boron nitride nanosheets and titanium dioxide-coated glass microspheres into the mixed solvent, and disperse them with a high-speed shear disperser to form a homogeneous pre-dispersion slurry; S1.

3. Resin mixing and defoaming: Place the resin matrix in a closed container equipped with stirring and heating functions for melt blending to form a molten mixture. Then, add the pre-dispersion slurry, as well as a curing agent, a promoter and an anti-aging agent to the molten mixture. At this time, place it in an environment with a vacuum degree ≤ -0.095 MPa for stirring and defoaming; S1.

4. Curing and molding: Coat the defoamed die-bonding glue material on the LED bracket, and adopt a step curing process to finally obtain a reflective die-bonding glue material for LED bracket packaging.

9. The preparation process of the reflective die bonding glue material based on nanoparticle dispersion technology according to claim 8, characterized in that, The step curing process includes a first stage of raising the temperature to 110°C - 120°C for pre-curing to form a preliminary three-dimensional network structure; a second stage of raising the temperature to 140°C - 160°C to completely crosslink the resin to form a stable solid structure; and a post-curing stage of raising the temperature to 200°C - 220°C.

10. Application of a reflective die bonding glue material based on nanoparticle dispersion technology, characterized in that, Application of the reflective die-bonding glue material based on nanoparticle dispersion technology according to any one of claims 1 - 7 in the packaging of 2W - 8W power LED brackets and LED chip substrates.

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