An impact-resistant high-performance epoxy resin packaging material and a preparation method thereof

Abstract

The application belongs to the technical field of electronic manufacturing packaging materials, and particularly relates to an impact-resistant high-performance epoxy resin packaging material and a preparation method thereof. The material is composed of an epoxy resin matrix A, a curing system B, an impact-resistant toughening system C, inorganic fillers D and interface bonding and reliability additives E. The curing system B adopts a pure phenolic resin system, so that the curing network is uniform and the internal stress is low. The impact-resistant toughening system C is composed of polyether sulfone and acrylate core-shell particles in cooperation, so that high energy consumption is realized. The inorganic fillers D construct a low-expansion high-thermal-conductivity skeleton to reduce thermal stress. Defects are inhibited by combining double-interface strengthening and gradient dispersion processes, and the obtained material has excellent impact resistance, heat resistance and reliability.

Description

Technical Field

[0001] This invention belongs to the field of electronic manufacturing packaging materials technology, specifically relating to an impact-resistant high-performance epoxy resin packaging material and its preparation method. Background Technology

[0002] Epoxy resin encapsulation materials are widely used in integrated circuit packaging, power device packaging, automotive electronic modules, and the potting and molding of various electronic components due to their excellent adhesion, electrical insulation, chemical corrosion resistance, and mature molding processes. They are used to achieve structural fixation, interconnect protection, and environmental isolation of devices. As electronic products develop towards high integration, miniaturization, thinning, and high power density, the spacing between solder joints / bumps in the packaging structure is constantly decreasing, and the interconnect areas are becoming thinner and more fragile. During assembly, transportation, and use, devices inevitably experience multi-field coupled loads such as drop impacts, mechanical vibrations, assembly compression, and thermal cycling / thermal shock, leading to a significant increase in the risk of packaging failure.

[0003] Existing epoxy resin encapsulation materials commonly suffer from the following pain points and defects in practical applications: Material brittleness and crack propagation are prominent issues. Conventional epoxy-cured networks have high crosslinking density, exhibiting high modulus in the glassy state but insufficient toughness. Microcracks easily initiate under transient impact loads or stress concentration areas (such as chip corners, solder joint perimeters, and interface corners), and further propagate under repeated impacts or vibrations, ultimately leading to encapsulation cracking, solder joint breakage, or functional failure. Thermal expansion mismatch-induced thermo-mechanical coupling failure is another major challenge. Significant CTE differences exist between the chip (silicon), solder joint metal, and organic substrate / encapsulation material. During temperature cycling, periodic shear stress is generated in the interconnect region. If the encapsulation material lacks sufficient toughness or interface strength, interface delamination and debonding easily occur, accelerating solder joint fatigue cracking. This problem is more pronounced in high-power devices, automotive applications, and high-density packaging. Uneven bonding and stress transfer at the interface lead to insufficient protection of solder joints. Traditional packaging materials often emphasize strength or hardness, but under impact conditions, if the material is too hard and lacks energy dissipation mechanisms, stress will be concentrated and transferred to the solder joints / bumps and weak areas of the interface, resulting in a failure mode where "the material itself is not damaged but the interconnects fail first." If the material is too soft, it may cause insufficient support, increased warpage, or long-term creep, leading to reduced reliability. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide an impact-resistant high-performance epoxy resin encapsulation material and its preparation method.

[0005] The technical effects described in this invention are achieved through the following technical solution: an impact-resistant high-performance epoxy resin encapsulation material, which is composed of an epoxy resin matrix A, a curing system B, an impact-resistant toughening system C, an inorganic filler D, and an interface bonding and reliability aid E.

[0006] Further, the epoxy resin matrix A is composed of 50-65 parts of bisphenol A type epoxy resin, 15-30 parts of bisphenol F type epoxy resin and 10-20 parts of o-cresol formaldehyde epoxy resin by weight.

[0007] Furthermore, the curing system B is composed of 50-80 parts of phenolic resin curing agent and 0.2-1 parts of catalyst by weight;

[0008] Furthermore, the phenolic resin curing agent is any one of bisphenol A type phenolic resin, phosphorophenolic resin, and p-tert-butylphenolic resin;

[0009] Further, the catalyst is any one of 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, triethylamine, triethanolamine, and ethyltriphenylphosphine acetate;

[0010] Furthermore, the impact-resistant toughening system C is composed of 6-12 parts of acrylate core-shell particles and 4-8 parts of polyethersulfone by weight.

[0011] Further, the core material of the acrylate core-shell particles is acrylate rubber; the shell material is any one of polymethyl methacrylate, styrene-methyl methacrylate copolymer, and styrene-acrylonitrile copolymer; the mass ratio of the core layer to the shell layer is 50:50 to 80:20; more preferably, the shell material is polymethyl methacrylate;

[0012] Furthermore, the average particle size of the acrylate core-shell particles is 100–300 nm;

[0013] It should be noted that the acrylate core-shell particles can be prepared using emulsion polymerization methods known in the art, such as seed emulsion polymerization, where an acrylate rubber core layer is first synthesized, and then a shell polymer is grafted onto the surface of the core layer. By controlling the reaction conditions, particles with a particle size of 100-300 nm can be obtained.

[0014] Furthermore, the inorganic filler D is composed of 500-720 parts of spherical fused silica, 8-20 parts of nano silica, 5-30 parts of boron nitride and 3-6 parts of silane coupling agent by weight.

[0015] Further, the silane coupling agent is any one of KH550 coupling agent, KH560 coupling agent, and KH570 coupling agent; more preferably, it is KH560 coupling agent;

[0016] Furthermore, the interface bonding and reliability aid E is composed of 0.4 to 1 part of bonding promoter, 0.1 to 0.3 parts of polyether modified polysiloxane defoamer and 0.5 to 1.5 parts of release agent by weight.

[0017] Furthermore, the adhesion promoter is any one of aminosilane, epoxysilane, and mercaptosilane;

[0018] Furthermore, the release agent is any one of zinc stearate, calcium stearate, and magnesium stearate;

[0019] Another aspect of the present invention is to provide a method for preparing an impact-resistant high-performance epoxy resin encapsulation material, specifically comprising the following preparation process:

[0020] S1: Place spherical molten silica, nano silica and boron nitride in an oven and dry until the moisture content is ≤0.2wt%. Cool to room temperature for later use. Take the dried inorganic filler, add silane coupling agent, and coat it using a high-speed dry mixing method at a speed of 1500-2500 rpm for 10-20 min. Control the powder temperature ≤60℃ during the mixing process to ensure uniform distribution of the coupling agent. React at 80-120℃ for 1-3 h to obtain surface-modified inorganic filler D.

[0021] S2: Add bisphenol A type epoxy resin, bisphenol F type epoxy resin and o-cresol epoxy resin into the reaction vessel according to the ratio, heat to 60-90℃, stir until the system is homogeneous, and obtain epoxy resin matrix A.

[0022] S3: Add phenolic resin curing agent to epoxy resin matrix A in S2, heat to 100-140℃, stir to fully melt and uniformly disperse the curing agent, then heat to 140-170℃, add polyethersulfone, stir and keep warm for 1-2 hours to dissolve evenly, then cool the system to 80-120℃, add acrylate core-shell particles, and shear and disperse at 1000-2000 rpm for 60-100 minutes to obtain toughened premixed resin;

[0023] S4: Add the surface-modified inorganic filler D from S1 to the toughening premixed resin from step S3 in 4 to 10 gradients, keeping the system temperature at 70 to 110°C. After each addition, disperse the resin under high shear conditions of 2000 to 4000 rpm for 10 to 30 minutes. After all the filler has been added, continue to disperse for 60 to 120 minutes to obtain a high-filler homogeneous system.

[0024] S5: Cool the high-filler homogeneous system of S4 to 50-80℃, add the adhesion promoter, polyether-modified polysiloxane defoamer, and release agent in sequence, and mix evenly; further cool the system to 45-60℃, add the catalyst, mix evenly, and degas under vacuum to obtain the encapsulation material.

[0025] The beneficial effects of this invention are as follows:

[0026] Compared with existing epoxy resin encapsulation materials, this invention uses a phenolic resin curing system and combines a process path of pre-melting and uniformly dispersing the curing agent and post-adding the catalyst. This improves the uniformity and controllability of the cured network, reduces the tendency for residual internal stress concentration, thereby reducing crack initiation and improving the mechanical properties and reliability of the encapsulation material. Simultaneously, this invention constructs an impact-resistant toughening system synergistically composed of polyethersulfone and acrylate core-shell particles. The polyethersulfone forms a stable toughening phase to improve the material's toughness without significantly sacrificing heat resistance. Under impact loads, the core-shell particles achieve toughening through cavitation, shear banding, and crack passivation. The mechanism achieves high-efficiency energy consumption, thereby significantly improving the impact resistance, crack resistance, and crack propagation resistance of the package. Furthermore, this invention uses spherical fused silica as the main filler to construct a low-thermal-expansion framework and reduce curing shrinkage and warpage. A small amount of nano-silica is used to achieve microstructure reinforcement and crack deflection. Boron nitride is added to enhance thermal conductivity and thermal diffusion to reduce temperature gradients and peak thermal stress, enabling the material to effectively disperse stress and suppress stress concentration around solder joints / bumps even under thermo-mechanical coupling conditions such as drop impacts and thermal cycling. In addition, this invention uses a silane coupling agent to surface-treat the inorganic filler, especially for those with abundant surface hydroxyl groups. Rich silica fillers form significant interfacial chemical bonds and simultaneously improve the wetting and compatibility of the composite filler system, thereby enhancing the filler-resin interfacial bonding and reducing the risk of interfacial voids and debonding in high-filler systems. Furthermore, the internal addition of adhesion promoters improves the adhesion strength of the encapsulation material to the chip / substrate interface. These two agents act on different targets and have complementary functions, significantly reducing delamination and peeling failures, thus ensuring that the toughening effect truly translates into improved encapsulation reliability. Moreover, this invention employs a process of "high-temperature pre-dissolution of polyethersulfone (PES) - dispersion of acrylate core-shell particles (CSR) - gradient addition of surface-modified fillers." The process path of "-additive homogenization-vacuum degassing" suppresses filler agglomeration / settling and air-entrapment voids, expands the processable window, and improves batch consistency and molding yield. At the same time, this invention does not use a strong polar surfactant system that easily introduces moisture absorption and ionic risks. Combined with a high-filler, low-moisture-absorbing skeleton and encapsulation-grade additives, it is beneficial to balance electrical performance and moisture and heat resistance reliability. Ultimately, the impact-resistant high-performance epoxy resin encapsulation material significantly improves impact resistance, crack resistance, delamination resistance, and long-term reliability while maintaining heat resistance, dimensional stability, and moldability. It is suitable for applications such as chip interconnect reinforcement and molding underfill / molding encapsulation. Attached Figure Description

[0027] Figure 1 The graph shows the results of the impact strength retention rate of the packaging materials under temperature cycling for Embodiment 1 and Comparative Examples 1-6 of the present invention.

[0028] Figure 2 The graph shows the shear strength retention rate of the packaging materials under temperature cycling for Embodiment 1 and Comparative Examples 1-6 of the present invention.

[0029] Figure 3 The graph shows the peel strength retention rate of the packaging materials under temperature cycling in Embodiment 1 and Comparative Examples 1-6 of the present invention.

[0030] Figure 4 The images show the FTIR spectra of the SiO2 filler used in Embodiment 1 of this invention before and after modification.

[0031] Figure 5 The images shown are FTIR images of the encapsulation material before and after curing in Embodiment 1 of the present invention. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the raw materials involved in the present invention are all purchased through conventional commercial channels. Experimental methods without specific conditions are conventional methods and conditions well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0033] Example 1: An impact-resistant high-performance epoxy resin encapsulation material, which is composed of epoxy resin matrix A, curing system B, impact-resistant toughening system C, inorganic filler D, and interface adhesion and reliability aid E;

[0034] The epoxy resin matrix A is composed of 60 parts by weight of bisphenol A type epoxy resin, 25 parts by weight of bisphenol F type epoxy resin and 15 parts by weight of o-cresol formaldehyde epoxy resin.

[0035] The curing system B is composed of 70 parts by weight of phenolic resin curing agent and 0.6 parts by weight of catalyst;

[0036] The impact-resistant toughening system C is composed of 10 parts of acrylate core-shell particles and 6 parts of polyethersulfone by weight.

[0037] The core material of the acrylate core-shell particles is acrylate rubber; the shell material is polymethyl methacrylate; the mass ratio of the core layer to the shell layer is 60:40.

[0038] The average particle size of the acrylate core-shell particles is 200 nm.

[0039] The inorganic filler D is composed of 650 parts of spherical fused silica, 15 parts of nano silica, 15 parts of boron nitride and 5 parts of silane coupling agent by weight.

[0040] The interface adhesion and reliability aid E consists of 0.8 parts adhesion promoter, 0.2 parts polyether modified polysiloxane defoamer and 1 part release agent;

[0041] The preparation method of the impact-resistant high-performance epoxy resin encapsulation material specifically includes the following preparation process:

[0042] S1: Place spherical molten silica, nano silica and boron nitride in an oven and dry until the moisture content is ≤0.2wt%. Cool to room temperature for later use. Take the dried inorganic filler, add KH560 coupling agent, and coat it using a high-speed dry mixing method at 2000 rpm for 15 min. Control the powder temperature ≤60℃ during the mixing process to ensure uniform distribution of the coupling agent. React at 100℃ for 1.5 h to obtain surface-modified inorganic filler D.

[0043] S2: Add bisphenol A type epoxy resin, bisphenol F type epoxy resin and o-cresol epoxy resin into the reaction vessel according to the ratio, heat to 80°C, and stir until the system is homogeneous to obtain epoxy resin matrix A.

[0044] S3: Add bisphenol A type phenolic resin to epoxy resin matrix A in S2, heat to 120℃, stir until fully melted and uniformly dispersed, then heat to 160℃, add polyethersulfone, stir and keep warm for 1.5h to dissolve evenly, then cool the system to 100℃, add acrylate core-shell particles, and shear and disperse at 1500rpm for 80min to obtain toughened premixed resin;

[0045] S4: The surface-modified inorganic filler D from S1 is added to the toughening premixed resin from step S3 in 8 gradients, while maintaining the system temperature at 90℃. After each addition, the resin is dispersed for 20 min under high shear conditions at 3000 rpm. After all the filler has been added, the resin is dispersed for another 90 min to obtain a highly filler-rich homogeneous system.

[0046] S5: Cool the high-filler homogeneous system of S4 to 65°C, add epoxy silane, polyether-modified polysiloxane defoamer and zinc stearate in sequence, and mix evenly; further cool the system to 50°C, add 2-methylimidazole, mix evenly, and degas under vacuum to obtain the encapsulation material.

[0047] Example 2: An impact-resistant high-performance epoxy resin encapsulation material, which is composed of epoxy resin matrix A, curing system B, impact-resistant toughening system C, inorganic filler D, and interface adhesion and reliability aid E;

[0048] The epoxy resin matrix A is composed of 65 parts by weight of bisphenol A type epoxy resin, 30 parts by weight of bisphenol F type epoxy resin and 20 parts by weight of o-cresol formaldehyde epoxy resin.

[0049] The curing system B is composed of 80 parts by weight of phenolic resin curing agent and 1 part by weight of catalyst;

[0050] The impact-resistant toughening system C is composed of 12 parts of acrylate core-shell particles and 8 parts of polyethersulfone by weight.

[0051] The core material of the acrylate core-shell particles is acrylate rubber; the shell material is styrene-methyl methacrylate copolymer; the mass ratio of the core layer to the shell layer is 50:50.

[0052] The average particle size of the acrylate core-shell particles is 100 nm.

[0053] The inorganic filler D is composed of 720 parts by weight of spherical fused silica, 20 parts by weight of nano silica, 30 parts by weight of boron nitride and 6 parts by weight of silane coupling agent;

[0054] The interface adhesion and reliability aid E consists of 1 part adhesion promoter, 0.3 parts polyether modified polysiloxane defoamer and 1.5 parts release agent;

[0055] The preparation method of the impact-resistant high-performance epoxy resin encapsulation material specifically includes the following preparation process:

[0056] S1: Place spherical molten silica, nano silica and boron nitride in an oven and dry until the moisture content is ≤0.2wt%. Cool to room temperature for later use. Take the dried inorganic filler, add KH550 coupling agent, and coat it using a high-speed dry mixing method at 2500rpm for 10min. Control the powder temperature ≤60℃ during the mixing process to ensure uniform distribution of the coupling agent. React at 120℃ for 1h to obtain surface-modified inorganic filler D.

[0057] S2: Add bisphenol A type epoxy resin, bisphenol F type epoxy resin and o-cresol epoxy resin into the reaction vessel according to the ratio, heat to 90°C, and stir until the system is homogeneous to obtain epoxy resin matrix A.

[0058] S3: Add p-tert-butylphenol resin to epoxy resin matrix A in S2, heat to 140℃, stir until fully melted and uniformly dispersed, then heat to 170℃, add polyethersulfone, stir and keep warm for 1 hour to dissolve evenly, then cool the system to 120℃, add acrylate core-shell particles, and shear and disperse at 2000 rpm for 60 minutes to obtain toughened premixed resin;

[0059] S4: The surface-modified inorganic filler D from S1 is added to the toughening premixed resin from step S3 in 10 gradients, keeping the system temperature at 110℃. After each addition, the resin is dispersed for 10 min under high shear conditions at 4000 rpm. After all the filler has been added, the resin is dispersed for another 60 min to obtain a high-filler homogeneous system.

[0060] S5: Cool the high-filler homogeneous system of S4 to 80°C, add aminosilane, polyether-modified polysiloxane defoamer, and calcium stearate in sequence, and mix evenly; further cool the system to 60°C, add 2-ethyl-4-methylimidazole, mix evenly, and degas under vacuum to obtain the encapsulation material.

[0061] Example 3: An impact-resistant high-performance epoxy resin encapsulation material, which is composed of epoxy resin matrix A, curing system B, impact-resistant toughening system C, inorganic filler D, and interface adhesion and reliability aid E;

[0062] The epoxy resin matrix A is composed of 50 parts by weight of bisphenol A type epoxy resin, 15 parts by weight of bisphenol F type epoxy resin and 10 parts by weight of o-cresol formaldehyde epoxy resin.

[0063] The curing system B is composed of 50 parts by weight of phenolic resin curing agent and 0.2 parts by weight of catalyst;

[0064] The impact-resistant toughening system C is composed of 6 parts acrylate core-shell particles and 4 parts polyethersulfone by weight.

[0065] The core material of the acrylate core-shell particles is acrylate rubber; the shell material is styrene-acrylonitrile copolymer; the mass ratio of the core layer to the shell layer is 80:20.

[0066] The average particle size of the acrylate core-shell particles is 100 nm.

[0067] The inorganic filler D is composed of 500 parts of spherical fused silica, 8 parts of nano silica, 5 parts of boron nitride and 3 parts of silane coupling agent by weight.

[0068] The interface adhesion and reliability aid E is composed of 0.4 parts adhesion promoter, 0.1 parts polyether modified polysiloxane defoamer and 0.5 parts release agent;

[0069] The preparation method of the impact-resistant high-performance epoxy resin encapsulation material specifically includes the following preparation process:

[0070] S1: Place spherical molten silica, nano silica and boron nitride in an oven and dry until the moisture content is ≤0.2wt%. Cool to room temperature for later use. Take the dried inorganic filler, add KH570 coupling agent, and coat it using a high-speed dry mixing method at 1500rpm for 20min. Control the powder temperature ≤60℃ during the mixing process to ensure uniform distribution of the coupling agent. React at 80℃ for 3h to obtain surface-modified inorganic filler D.

[0071] S2: Add bisphenol A type epoxy resin, bisphenol F type epoxy resin and o-cresol epoxy resin into the reaction vessel according to the ratio, heat to 60°C, and stir until the system is homogeneous to obtain epoxy resin matrix A.

[0072] S3: Add phosphorophenolic resin to epoxy resin matrix A in S2, heat to 100℃, stir until fully melted and uniformly dispersed, then heat to 140℃, add polyethersulfone, stir and keep warm for 2 hours to dissolve evenly, then cool the system to 80℃, add acrylate core-shell particles, and shear and disperse at 1000 rpm for 100 min to obtain toughened premixed resin.

[0073] S4: The surface-modified inorganic filler D from S1 is added to the toughening premixed resin from step S3 in four gradients, keeping the system temperature at 70℃. After each addition, the mixture is dispersed for 30 minutes under high shear conditions at 2000 rpm. After all the filler has been added, the mixture is dispersed for another 120 minutes to obtain a highly filler-rich homogeneous system.

[0074] S5: Cool the high-filler homogeneous system of S4 to 50°C, add mercaptosilane, polyether-modified polysiloxane defoamer, and magnesium stearate in sequence, and mix evenly; further cool the system to 45°C, add triethanolamine, mix evenly, and degas under vacuum to obtain the encapsulation material.

[0075] Comparative Example 1: In Comparative Example 1, polyethersulfone was removed and the amount of epoxy resin matrix A was added to make up the difference. The composition and process of the remaining raw materials were the same as in Example 1.

[0076] Comparative Example 2: In Comparative Example 2, the acrylate core-shell particles were removed, and the mixture was made up with an equal weight of epoxy resin matrix A. The composition and process of the remaining raw materials were the same as in Example 1.

[0077] Comparative Example 3: The silane coupling agent was removed in Comparative Example 3, while the composition of the remaining raw materials and the process were the same as in Example 1.

[0078] Comparative Example 4: The adhesion promoter was removed in Comparative Example 4, and the composition and process of the remaining raw materials were the same as in Example 1.

[0079] Comparative Example 5: In Comparative Example 5, step S4 is not performed with gradient feeding, but with all fillers added at once. The composition and process of the remaining raw materials are the same as in Example 1.

[0080] Comparative Example 6: In Comparative Example 6, the catalyst addition in step S5 was changed from post-addition to pre-addition. That is, the phenolic resin curing agent was added in step S3 and allowed to fully melt and disperse evenly before the catalyst was added. The composition and process of the remaining raw materials were the same as in Example 1.

[0081] Performance testing:

[0082] Preparation of test samples: The impact-resistant high-performance epoxy resin encapsulation material prepared according to the method of this invention was used to prepare test samples by transfer molding process; the specific molding conditions are as follows: the size of the flat mold is 150mm×150mm×4mm; the mold temperature is controlled at 160°C and the holding time is 8min; the molded sample is post-cured in a hot air circulating oven at 160°C for 2h; after post-curing, the sample is placed in a standard environment (temperature 25°C, relative humidity 50%RH) for 48h for subsequent performance testing.

[0083] Mechanical property testing: Based on GB / T 40564-2021, samples of corresponding specifications were cut from the plate sample after the above-mentioned condition adjustment. Impact strength, shear strength and peel strength were tested on the packaging materials of Examples 1-3 and Comparative Examples 1-6. The results are shown in Table 1 below.

[0084] Table 1. Test results of mechanical properties of packaging materials in the examples and comparative examples

[0085]

[0086] Based on the results in Table 1, the embodiments of the present invention employ a phenolic resin curing network, synergistic toughening of polyethersulfone / acrylate core-shell particles, synergistic strengthening of the interface through silane surface modification of filler and internal doping with adhesive promoters, and achieve low-defect molding of the high-filler system through gradient feeding and high shear dispersion. Therefore, a consistent improvement is achieved in the three indicators of impact strength, shear strength and peel strength. Comparative Examples 1 and 2, by removing polyethersulfone and acrylate core-shell particles respectively, resulted in an incomplete multi-scale energy dissipation mechanism, significantly weakened crack passivation and propagation inhibition capabilities, and the most significant decrease in impact strength. Simultaneously, the reduction in toughening phase / energy-dissipating particles indirectly reduced the stress buffering capacity between the interface and the matrix, leading to a synchronous decrease in shear and peel strength. In Comparative Example 3, the removal of filler silane modification weakened the filler-resin interface bonding and made it more prone to interface debonding and micro-defects, reducing load transfer efficiency and thus significantly deteriorating shear and peel strength. Impact fracture was also more likely to initiate at interface defects, resulting in reduced impact strength and increased dispersion. In Comparative Example 4, the removal of the adhesion promoter reduced the bonding force between the encapsulation material and the substrate interface, making cracks more likely to propagate along the interface, resulting in the most significant decrease in peel strength and a substantial reduction in shear strength. Furthermore, the interface became a weaker path, reducing effective energy dissipation and stress dispersion during impact, further decreasing impact strength. In Comparative Example 5, with the filler added only once, agglomeration nuclei and air-filled voids were more likely to form, leading to significant defect sources in both the bulk phase and interface, resulting in the lowest overall mechanical properties and the greatest fluctuation. In Comparative Example 6, changing the catalyst addition from post-addition to pre-addition made the system more prone to reacting prematurely during the high-temperature mixing stage, which accelerated the increase in viscosity. This was not conducive to the full wetting, uniform dispersion, and degassing of the subsequent fillers, and caused uneven local cross-linking and concentration of residual internal stress.

[0087] Temperature cycling mechanical property test: The encapsulation materials of Example 1 and Comparative Examples 1-6 were subjected to temperature cycling tests between -40℃ and 125℃, with exposure for 10 minutes at each extreme temperature. After 500 and 1000 temperature cycles, the retention rates (%) of impact strength, shear strength, and peel strength were measured respectively. The results were calculated as follows: (After cycling / Before cycling) × 100%. Figure 1 , Figure 2 and Figure 3 As shown.

[0088] based on Figure 1 , Figure 2 and Figure 3Results analysis showed that Example 1 possesses a multi-scale toughening effect from polyethersulfone / core-shell particles, enhanced filler-resin interface bonding through silane surface modification, improved adhesion to the substrate interface through internal adhesion promoters, and a low-void, low-agglomeration structure resulting from gradient feeding and high shear dispersion. Therefore, it maintained high impact resistance, shear and peel retention rates with a slow decay rate after 500 and 1000 cycles, respectively. Comparative Examples 1 and 2 lacked polyethersulfone and core-shell particles, respectively, resulting in an incomplete bulk energy dissipation mechanism. Microcracks generated by temperature cycling were more difficult to passivate and impede, leading to a more significant decrease in impact resistance retention rate. Furthermore, insufficient stress buffering capacity indirectly promoted interfacial micro-debonding, resulting in a decrease in shear and peel retention rates, but still significantly better than the comparative examples dominated by interfacial chemical or process defects. In Comparative Example 3, after removing the filler and modifying with silane, the filler-resin interface was more prone to micro-debonding under cyclic shear stress. Micro-defects accumulated and expanded into interface damage and delamination, causing a significant decrease in shear and peel retention rates after 500 cycles, and a further substantial decline after 1000 cycles. Simultaneously, interface defects became the preferred growth path for impact cracks, leading to a simultaneous decrease in impact retention rate. In Comparative Example 4, after removing the adhesion promoter, the encapsulation material's interfacial bonding to the substrate was insufficient. Temperature cycling made it easier for delamination to form along the interface and propagate rapidly, resulting in the most significant decrease in peel retention rate. Shear retention rate also decreased significantly. While impact resistance remained relatively high due to bulk toughening, cracks tended to propagate along the interface after interface weakening, so the retention rate was still lower than in Example 1. In Comparative Example 5, the one-time addition of filler made it more difficult to eliminate agglomeration nuclei and air-filled voids. During temperature cycling, these defects became stress concentration sources and accelerated crack initiation and interface propagation, resulting in the lowest retention rates for impact, shear, and peel resistance, with the most severe decline after 1000 cycles. In Comparative Example 6, changing the catalyst addition from post-addition to pre-addition made the system more prone to partial reaction during the high-temperature mixing stage, resulting in uneven local crosslinking density distribution, limited filler wetting and degassing, and the formation of high residual internal stress after curing. During temperature cycling, these uneven areas and stress concentration areas are more likely to generate and expand microcracks, while also promoting intensified interfacial micro-debonding, leading to a significant decrease in impact resistance, shear resistance, and peeling retention rate.

[0089] Spectral Testing: Fourier transform infrared (FTIR) spectroscopy was performed on the SiO2 filler before and after silane modification in Example 1, and on the encapsulation material before and after curing in Example 1 (samples before curing were taken from the encapsulation material after S5 vacuum degassing and before molding; samples after curing were taken from the surface of the molded and post-cured sample). The results are as follows: Figure 4 and Figure 5 As shown.

[0090] based on Figure 4 and Figure 5Results analysis showed that, compared with unmodified SiO2, the filler treated with KH560 had a thickness of 2855-2960 cm⁻¹. -1 At 3400 cm⁻¹, CH stretching vibration-related absorption was observed / enhanced. -1 The near-terminal hydroxyl peak shows a decreasing trend, indicating that the organic segments of the silane coupling agent were successfully introduced into the filler surface and surface modification was achieved, which is beneficial to improving the interfacial compatibility and bonding stability between the filler and the epoxy group. On the other hand, the FTIR comparison of the encapsulation material before and after curing shows that the characteristic absorption of epoxy group-related features after curing (915 cm⁻¹) is decreasing. -1 The value of the area (nearby) decreased significantly, while the value of the area (1100-1200cm) also decreased significantly. -1 The absorption associated with the ether bond / ring-opening curing structure shows an increasing trend, indicating that the epoxy system undergoes sufficient ring-opening curing and forms a stable cross-linked network under transfer molding and post-curing conditions.

[0091] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-performance, impact-resistant epoxy resin encapsulation material, characterized in that, It consists of an epoxy resin matrix A, a curing system B, an impact-resistant toughening system C, an inorganic filler D, and an interfacial bonding and reliability aid E; The epoxy resin matrix A is composed of bisphenol A type epoxy resin, bisphenol F type epoxy resin and o-cresol formaldehyde epoxy resin; The curing system B consists of a phenolic resin curing agent and a catalyst; The impact-resistant toughening system C is composed of acrylate core-shell particles and polyethersulfone; The inorganic filler D is composed of spherical fused silica, nano silica, boron nitride and silane coupling agent; The interface adhesion and reliability aid E is composed of an adhesion promoter, a polyether-modified polysiloxane defoamer, and a release agent; The impact-resistant high-performance epoxy resin encapsulation material is prepared by the following method: S1: Place spherical molten silica, nano silica and boron nitride in an oven, dry them, and cool them to room temperature for later use; take the dried inorganic filler, add silane coupling agent, and use a high-speed mixing dry coating method to make the coupling agent evenly distributed and react to obtain surface-modified inorganic filler D; S2: Add bisphenol A type epoxy resin, bisphenol F type epoxy resin and o-cresol epoxy resin into the reaction vessel according to the ratio, heat up and stir until the system is homogeneous to obtain epoxy resin matrix A. S3: Add phenolic resin curing agent to epoxy resin matrix A in S2, heat up, stir to fully melt and uniformly disperse the curing agent, then continue to heat up, add polyethersulfone, stir and keep warm to dissolve evenly, then cool the system, add acrylate core-shell particles, and shear and disperse to obtain toughened premixed resin. S4: The surface-modified inorganic filler D from S1 is added in a gradient to the toughened premixed resin from step S3. The system temperature is maintained, and the resin is dispersed under high shear conditions after each addition. After all the filler is added, shear treatment is continued to disperse the resin evenly, resulting in a highly filler-rich homogeneous system. S5: Cool down the high-filler homogeneous system of S4, and add the adhesion promoter, polyether-modified polysiloxane defoamer, and release agent in sequence, and mix them evenly; cool down the system, add the catalyst, mix evenly, and degas under vacuum to obtain the encapsulation material.

2. The impact-resistant high-performance epoxy resin encapsulation material according to claim 1, characterized in that, The epoxy resin matrix A is composed of 50-65 parts of bisphenol A type epoxy resin, 15-30 parts of bisphenol F type epoxy resin and 10-20 parts of o-cresol formaldehyde epoxy resin by weight.

3. The impact-resistant high-performance epoxy resin encapsulation material according to claim 1, characterized in that, The curing system B is composed of 50-80 parts of phenolic resin curing agent and 0.2-1 parts of catalyst by weight.

4. The impact-resistant high-performance epoxy resin encapsulation material according to claim 1, characterized in that, The phenolic resin curing agent is any one of bisphenol A type phenolic resin, phosphorophenolic resin, and p-tert-butylphenolic resin; the catalyst is any one of 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, triethylamine, triethanolamine, and ethyltriphenylphosphine acetate.

5. The impact-resistant high-performance epoxy resin encapsulation material according to claim 1, characterized in that, The impact-resistant toughening system C is composed of 6-12 parts of acrylate core-shell particles and 4-8 parts of polyethersulfone by weight.

6. The impact-resistant high-performance epoxy resin encapsulation material according to claim 1, characterized in that, The core material of the acrylate core-shell particles is acrylate rubber; the shell material is any one of polymethyl methacrylate, styrene-methyl methacrylate copolymer, and styrene-acrylonitrile copolymer; the mass ratio of the core layer to the shell layer is 50:50 to 80:20; and the average particle size of the acrylate core-shell particles is 100 to 300 nm.

7. The impact-resistant high-performance epoxy resin encapsulation material according to claim 1, characterized in that, The inorganic filler D is composed of 500-750 parts of spherical fused silica, 8-20 parts of nano silica, 5-30 parts of boron nitride, and 3-6 parts of silane coupling agent by weight.

8. The impact-resistant high-performance epoxy resin encapsulation material according to claim 1, characterized in that, The silane coupling agent is any one of KH550 coupling agent, KH560 coupling agent, and KH570 coupling agent.

9. The impact-resistant high-performance epoxy resin encapsulation material according to claim 1, characterized in that, The interface adhesion and reliability aid E is composed of 0.4 to 1 part of adhesion promoter, 0.1 to 0.3 parts of polyether modified polysiloxane defoamer, and 0.5 to 1.5 parts of release agent by weight; the adhesion promoter is any one of aminosilane, epoxysilane, and mercaptosilane; the release agent is any one of zinc stearate, calcium stearate, and magnesium stearate.

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