Partition functional underfill adhesive for large-area ai chip packaging and preparation method thereof

Abstract

The application discloses a partition functionalized underfill adhesive for large-area AI chip packaging and a preparation method, and belongs to the technical field of electronic packaging materials. The partition functionalized underfill adhesive is sequentially divided into a center region, a transition region and an edge region from inside to outside along a chip bonding surface. The center region is compounded by bisphenol F-naphthalene type epoxy resin and AlN@BN core-shell fillers, and has high modulus, low thermal expansion coefficient and high thermal conductivity. The edge region is compounded by epoxy-silicone interpenetrating network polymer and elastic core-shell fillers, and has low modulus and high elasticity. The transition region is obtained by gradient mixing of the center and edge adhesives, realizes continuous transition of mechanical and thermal properties, and eliminates interface mutation. The application also provides a corresponding preparation method. After the partition functionalized underfill adhesive is packaged, the chip warping amount is less than 20 mu m, the temperature cycle reliability is significantly improved, the HBM stacking and glass / organic substrate can be adapted, and the application is suitable for high-power large-area AI chip packaging.

Description

Technical Field

[0001] This invention belongs to the field of electronic packaging materials technology, and in particular relates to a partitioned functionalized bottom filler for large-area AI chip packaging and its preparation method. Background Technology

[0002] With the continuous evolution of artificial intelligence and high-performance computing, AI chips, as the core of computing power, are rapidly developing towards higher integration, larger area, higher power consumption, and higher heat flux density. Chip size has increased from the traditional 100-200 mm². 2 Extended to 800 mm 2 Above, and continuing towards 2500 mm 2 This trend has even led to breakthroughs in system-in-package (SoC) designs, reaching even larger sizes. While significantly increasing computing power density, this trend has also brought unprecedented mechanical and thermal management challenges to chip packaging.

[0003] In mainstream flip-chip packaging, underfill is widely used to fill the gap between the chip and the substrate, covering micro-solder joints. It plays a crucial role in dispersing thermomechanical stress, strengthening structural integrity, and protecting electrical connections. Its material properties directly determine the reliability, warpage control capability, and lifespan of the packaged module.

[0004] Traditional underfill adhesives are mostly homogeneous material systems, meaning their mechanical and thermal properties are uniformly distributed throughout the adhesive layer. This design can meet basic requirements for small-sized chips, but as chip sizes evolve to larger areas, its inherent limitations become increasingly apparent. Under temperature cycling or power fluctuations, large-area chips experience a significant mismatch in thermal expansion coefficients between the silicon chip (thermal expansion coefficient approximately 2.6 ppm / °C) and the organic substrate (thermal expansion coefficient approximately 17-50 ppm / °C), resulting in a significant non-uniform stress field in the packaging structure. The central region of the chip primarily exhibits overall warpage and shear fatigue of the solder joints, requiring high-modulus, low-thermal-expansion-coefficient materials to provide rigid support. Meanwhile, the chip edges and corners become the areas with the most severe stress concentration, easily leading to interface delamination or adhesive cracking, urgently requiring low-modulus, high-toughness materials for stress buffering.

[0005] However, traditional homogeneous underfillers must make trade-offs between "support" and "buffering" in their formulation design. While high-modulus, low-thermal-expansion-coefficient formulations help suppress overall warpage, their lack of deformation capacity can create stress singularities in edge regions, leading to interface failure. Conversely, low-modulus, high-elasticity formulations can absorb edge stress, but they are insufficient to provide adequate mechanical support in the chip's central region, potentially causing solder joint fatigue or even premature failure. Furthermore, their low filler content results in poor thermal conductivity, making it difficult to meet the heat dissipation requirements of high-power chips.

[0006] In recent years, the industry has attempted to improve the performance of underfillers by optimizing the resin matrix, introducing toughening phases, and controlling the morphology of fillers. However, these efforts remain limited to the framework of homogeneous materials and have failed to fundamentally overcome the core bottleneck that a single material cannot simultaneously meet the differentiated needs of multiple regions. Addressing the increasingly prominent contradiction between non-uniform stress fields and local performance requirements in large-area AI chip packaging, there is an urgent need to develop a novel underfill material system capable of spatially customizing mechanical and thermal properties to achieve a synergistic effect of "high support at the center and high buffering at the edges," thereby effectively controlling warpage and improving long-term reliability.

[0007] Based on this, the present invention proposes a partitioned functionalized bottom filler and its preparation method. Through a three-stage differentiated formulation design of "center-transition-edge" and gradient mixing technology, a continuous gradient distribution of material properties is achieved within the same package, providing a practical and feasible technical path to solve the above problems. Summary of the Invention

[0008] The purpose of this invention is to provide a partitioned functionalized underfill adhesive and its preparation method for large-area AI chip packaging. The partitioned functionalized underfill adhesive achieves spatially customized distribution of material properties within the same device through an innovative three-stage differentiated formulation design and gradient mixing technology of "center-transition-edge". This achieves a synergistic effect of "high support at the center, high buffer at the edge, and no abrupt transition", thereby solving the technical problems of non-uniform stress and thermal management in large-area chip packaging in the prior art.

[0009] To solve the above-mentioned technical problems, the specific technical solution of the present invention is as follows:

[0010] A method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging, the method comprising the following steps:

[0011] Step S1: Using bisphenol F-naphthalene type epoxy resin as the matrix, a curing agent and an accelerator are compounded to construct a central region matrix mixture, and AlN@BN core-shell filler is filled in. After being dispersed evenly, the central region adhesive is prepared.

[0012] Step S2: Using bisphenol A type epoxy resin and hydroxyl-terminated polydimethylsiloxane as the matrix, a flexible curing agent is compounded to construct an epoxy-organosilicon interpenetrating network polymer, and polyurethane@silica core-shell elastic filler is filled to prepare the edge region adhesive.

[0013] Step S3: According to the AI ​​chip partitioning design, perform partitioned adhesive application before bonding the AI ​​chip to the substrate;

[0014] Step S4: After dispensing, the AI ​​chip is mounted, and then a stepped temperature curing process is used: first, it is cured at 120°C for 1 hour, and then cured at 150°C for 2 hours to form a performance-zoned bottom filler adhesive layer.

[0015] Further, step S1 includes the following steps:

[0016] Step S11: Mix 100 parts by weight of bisphenol F-naphthalene type epoxy resin, 85 parts by weight of methyl hexahydrophthalic anhydride curing agent, and 0.5 parts by weight of 1-cyanoethyl-2-ethyl-4-methylimidazolium accelerator, and stir and disperse evenly at 60°C to obtain a central region matrix mixture.

[0017] Step S12: Using AlN as the core and BN as the shell, a BN layer is coated on the surface of AlN by chemical vapor deposition, and finally the surface is treated with silane coupling agent to obtain AlN@BN core-shell filler;

[0018] Step S13: Add AlN@BN core-shell filler to the matrix mixture in the central region, place it in a planetary mixer, disperse it at 2000 rpm for 30 minutes, and then degas it under vacuum to obtain the central region compound.

[0019] Furthermore, in step S13, the amount of AlN@BN core-shell filler added is 50-75 parts by weight.

[0020] Further, step S2 includes the following steps:

[0021] Step S21: Mix 70 parts by weight of bisphenol A type epoxy resin, 30 parts by weight of hydroxyl-terminated polydimethylsiloxane, and 35 parts by weight of amino silicone oil flexible curing agent, and stir at 80°C for 1 hour to form an epoxy-organosilicon interpenetrating network polymer.

[0022] Step S22: Prepare a core-shell structure with polyurethane as the core and silica as the shell by emulsion polymerization or sol-gel method, and then perform surface treatment with silane coupling agent to obtain polyurethane@silica core-shell elastic filler.

[0023] Step S23: Add polyurethane@silica core-shell elastic filler to the epoxy-organosilicon interpenetrating network polymer, disperse evenly and degas under vacuum to obtain the edge region adhesive.

[0024] Furthermore, the amount of polyurethane@silica core-shell elastic filler added in step S23 is 30-50 parts by weight.

[0025] Further, step S3 includes the following steps:

[0026] Step S31: Use a dual-cylinder dispensing device, with cylinder A filled with adhesive for the central area and cylinder B filled with adhesive for the edge area;

[0027] Step S32: Based on the AI ​​chip, the substrate is partitioned into a central region, a transition region, and an edge region.

[0028] Step S33: Before the AI ​​chip is bonded to the substrate, for the central area, the dual-barrel dispensing equipment only outputs adhesive for the central area;

[0029] Step S34: For the edge area, the dual-barrel dispensing equipment only outputs adhesive material from the edge area;

[0030] Step S35: For the transition area, the dual-barrel dispensing equipment dynamically adjusts the output ratio of the adhesive in the central area and the adhesive in the edge area according to the preset gradient mixing program, forming a continuous transition in space from 100% central area adhesive / 0% edge area adhesive to 0% central area adhesive / 100% edge area adhesive.

[0031] Furthermore, the preset gradient mixing program in step S35 is a pre-defined function relating the mixing ratio of the adhesive in the central region to the adhesive in the edge region as the dispensing position changes; during the dispensing process, the control system adjusts the flow ratio of the two injection pumps in the dual-barrel dispensing equipment in real time according to the preset gradient curve, so that the mixing ratio changes continuously in the transition region.

[0032] Furthermore, the partitioned functionalized bottom filler is prepared by the method described in any one of claims 1-7, and the partitioned functionalized bottom filler is divided into a central region, a transition region, and an edge region from the inside out.

[0033] Furthermore, the formulation of the zoned functionalized underfill adhesive exhibits a differentiated distribution in the central, transition, and edge regions:

[0034] The central region adhesive is prepared by using bisphenol F-naphthalene type epoxy resin as the matrix, compounding curing agent and accelerator, and filling with AlN@BN core-shell filler;

[0035] The edge region adhesive is prepared by using bisphenol A type epoxy resin and hydroxyl-terminated polydimethylsiloxane as the matrix, compounding a flexible curing agent, and filling with polyurethane@silica core-shell elastic filler;

[0036] The transition region compound is made by blending the central region compound and the edge region compound in a spatial gradient ratio, wherein the volume fraction of the central region compound continuously decreases from 100% on the side adjacent to the central region to 0% on the side adjacent to the edge region.

[0037] Compared with the prior art, the present invention has the following beneficial technical effects:

[0038] 1) Pioneering performance space partitioning design to precisely match chip requirements: For the first time, a three-segment functional design of the bottom filler adhesive—"center-transition-edge"—was proposed and implemented. The high modulus, low CTE, and high thermal conductivity of the central region provide robust mechanical support and an efficient heat diffusion path for the high-density solder joints in the chip center. The low modulus and high elasticity of the edge region efficiently absorb and dissipate the concentrated stress generated at the chip edge due to CTE mismatch, effectively suppressing delamination and cracking. The gradient design of the transition region eliminates abrupt changes in the performance interface and avoids secondary stress concentration.

[0039] 2) Collaborative optimization, comprehensively breaking through reliability bottlenecks: This design systematically solves the contradiction between "support" and "buffering" in large-area chip packaging. Packaging tests show that the maximum warpage of the 50mm×50mm AI chip module using the bottom filler of this invention can be controlled within 20μm; after temperature cycling (TC1000) from -55°C to 125°C, the cracking rate of the adhesive layer and interface is less than 0.1%, and the reliability is significantly better than the control group using traditional homogeneous bottom filler.

[0040] 3) Highly innovative material system: The central region uses a bisphenol F-naphthalene epoxy / AlN@BN core-shell filler system, which, while ensuring high modulus and low CTE, improves filler dispersibility and interfacial compatibility through the BN shell, resulting in a better thermal conductivity path. The edge region uses an epoxy-silicone interpenetrating network / elastic core-shell filler system, achieving a molecular-level combination of rigidity and elasticity, with excellent stress buffering capacity and good compatibility with the central region's adhesive, facilitating the formation of a transition zone.

[0041] 4) The preparation process is feasible and compatible with existing production lines: The proposed dual-barrel gradient dispensing preparation method has a clear principle. Complex partitioning can be achieved through control software programming without modifying the core packaging equipment. It is easy to integrate into the existing large-scale flip chip packaging process and has a low industrialization threshold.

[0042] 5) Broad application prospects: This invention is particularly suitable for advanced packaging scenarios such as AI chips, GPUs, and HBM (high bandwidth memory) stacks with side lengths of 50-100 mm. It is also applicable to various packaging forms such as glass substrates and organic substrates, and has important value for promoting the advancement of packaging technology and improving the reliability of high computing power and large-size chips. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the dual-cylinder dispensing process for preparing the partitioned functionalized bottom filler adhesive of the present invention.

[0045] Figure 2 This is a schematic diagram of the partitioned structure of the chip packaging structure of the present invention.

[0046] Figure 3 This is a structural diagram showing a comparison of the material formulations of each region of the functionalized bottom filler adhesive of the present invention.

[0047] Figure 4 This is a schematic diagram showing the performance comparison of different regions of the functionalized bottom filler adhesive of the present invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] This invention proposes a method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging, the method comprising the following steps:

[0050] Step S1: Using bisphenol F-naphthalene type epoxy resin as the matrix, a curing agent and an accelerator are compounded to construct a central region matrix mixture, and AlN@BN core-shell filler is filled in. After uniform dispersion, the central region adhesive is prepared.

[0051] Specifically, step S1 includes the following steps:

[0052] Step S11: Mix 100 parts by weight of bisphenol F-naphthalene type epoxy resin (EPON 862), 85 parts by weight of methyl hexahydrophthalic anhydride curing agent (MHHPA), and 0.5 parts by weight of 1-cyanoethyl-2-ethyl-4-methylimidazolium accelerator (2E4MZ-CN), and stir and disperse evenly at 60°C to obtain a central region matrix mixture.

[0053] Step S12: Using AlN (aluminum nitride) as the core and BN (boron nitride) as the shell, a BN layer is deposited on the surface of AlN by chemical vapor deposition, and finally the surface is treated with a silane coupling agent to obtain AlN@BN core-shell filler.

[0054] Specifically, in the AlN@BN core-shell packing, the core is aluminum nitride (AlN) and the shell is boron nitride (BN). The BN shell layer accounts for 10%-30% of the total mass of the AlN@BN core-shell packing, with an average particle size of 5 μm. As an interface modification layer, the BN shell layer reduces the interfacial thermal resistance between the aluminum nitride core and the matrix mixture in the central region, and improves the dispersibility and suspension stability of the AlN@BN core-shell packing in bisphenol F-naphthalene type epoxy.

[0055] Step S13: Add AlN@BN core-shell filler to the matrix mixture in the central region, place it in a planetary mixer, disperse it at 2000 rpm for 30 minutes, and then degas it under vacuum to obtain the central region compound.

[0056] Specifically, the amount of AlN@BN core-shell filler added is 50-75 parts by weight. The high filling amount of AlN@BN core-shell still allows the core area of ​​the compound to have rheological properties suitable for dispensing.

[0057] The central region corresponds to the high-density solder joint area and heat source core area at the center of the chip, and its design goal is to provide rigid support and efficient heat dissipation. Therefore, the adhesive in the central region needs to have a high elastic modulus (≥12 GPa) after curing to match the low bending strain of the chip's central region and provide sufficient fatigue resistance support for the microbumps; at the same time, it needs to have a low coefficient of thermal expansion (CTE) (≤25 ppm / °C) to make its thermomechanical behavior closer to that of a silicon chip, reducing internal stress caused by thermal mismatch; and it needs to have a high thermal conductivity (≥2.5 W / (m·K)) to establish an efficient heat conduction channel for the chip center and reduce the junction temperature.

[0058] Step S2: Using bisphenol A type epoxy resin and hydroxyl-terminated polydimethylsiloxane as the matrix, a flexible curing agent is compounded to construct an epoxy-organosilicon interpenetrating network polymer, and polyurethane@silica core-shell elastic filler is filled to prepare the edge region adhesive.

[0059] Specifically, step S2 includes the following steps:

[0060] Step S21: Mix 70 parts by weight of bisphenol A type epoxy resin (E51), 30 parts by weight of hydroxyl-terminated polydimethylsiloxane (OH-PDMS), and 35 parts by weight of amino silicone oil flexible curing agent (KF-8010), and stir at 80°C for 1 hour to form an epoxy-organosilicon interpenetrating network polymer.

[0061] Step S22: Prepare a core-shell structure with polyurethane as the core and silica as the shell by emulsion polymerization or sol-gel method, and then perform surface treatment with silane coupling agent to obtain polyurethane@silica core-shell elastic filler.

[0062] Specifically, the core-shell structured elastic organic filler consists of polyurethane@silica core-shell particles, with a polyurethane core and a silica shell, and an average particle size of 2 μm. The silica shell accounts for 10%-30% of the total mass of the core-shell filler. The hard silica shell ensures uniform dispersion and storage stability of the elastic particles in the epoxy-organic silicone prepolymer, while the soft polyurethane core provides high elasticity and energy dissipation capacity to the edge regions after curing.

[0063] Step S23: Add polyurethane@silica core-shell elastic filler to the epoxy-organosilicon interpenetrating network polymer, disperse evenly and degas under vacuum to obtain the edge region adhesive.

[0064] Specifically, the amount of polyurethane@silica core-shell elastic filler added is 30-50 parts by weight.

[0065] The edge region corresponds to the stress concentration areas at the chip edges and corners, and its design goal is to absorb and dissipate mechanical stress. Therefore, the cured adhesive in the edge region needs to have a low elastic modulus (≤2 GPa) and a high elongation at break (≥60%) so that it can release stress through its own deformation when the chip warps or deforms, effectively suppressing interface delamination and adhesive cracking; its coefficient of thermal expansion can be controlled within a moderate range (30-45 ppm / °C), playing a gradual buffering role between the substrate and the chip.

[0066] Step S3: Based on the AI ​​chip partitioning design, perform partitioned adhesive application before bonding the AI ​​chip to the substrate.

[0067] Specifically, such as Figure 1 As shown, step S3 includes the following steps:

[0068] Step S31: Use a dual-cylinder dispensing device. Cylinder A is filled with adhesive for the central area, and cylinder B is filled with adhesive for the edge area.

[0069] Step S32: Based on the AI ​​chip, the substrate is partitioned into a central area, a transition area, and an edge area.

[0070] Step S33: Before the AI ​​chip is bonded to the substrate, the dual-barrel dispensing equipment only outputs adhesive material to the central area.

[0071] Step S34: For the edge area, the dual-barrel dispensing equipment only outputs adhesive material for the edge area.

[0072] Step S35: For the transition area, the dual-barrel dispensing equipment dynamically adjusts the output ratio of the adhesive in the central area and the adhesive in the edge area according to the preset gradient mixing program, forming a continuous transition in space from 100% central area adhesive / 0% edge area adhesive to 0% central area adhesive / 100% edge area adhesive.

[0073] Specifically, the preset gradient mixing program is a pre-defined function relating the mixing ratio of the adhesive in the central region to that in the edge region as a function of the dispensing position. During dispensing, the control system adjusts the flow rate ratio of the two injection pumps in the dual-barrel dispensing equipment in real time according to a preset gradient curve (such as a linear gradient or an S-shaped gradient), ensuring that the mixing ratio changes continuously within the transition region. To ensure uniform blending of the two adhesives during the mixing process, a static mixing tube (containing 12-24 mixing elements) can be connected to the rear end of the dispensing head to achieve uniform mixing at the microscale through multiple divisions and recombinations.

[0074] Step S4: After dispensing, the AI ​​chip is mounted, and then a stepped temperature curing process is used: first, it is cured at 120°C for 1 hour, and then cured at 150°C for 2 hours to form a performance-zoned bottom filler adhesive layer.

[0075] Furthermore, this invention also discloses a partitioned functionalized underfill adhesive prepared by the above method, such as... Figure 2 The bottom filler shown is divided into a central area, a transition area, and an edge area from the inside out. This "three-segment" differentiated formulation design achieves spatially customized performance distribution. For example... Figure 3 As shown, the formulation of the underfill adhesive exhibits a differentiated distribution in the central region, transition region, and edge region. For example... Figure 4 As shown, the properties of the underfill adhesive exhibit a differentiated distribution in the central region, transition region, and edge region.

[0076] The central region adhesive is prepared by using bisphenol F-naphthalene type epoxy resin as the matrix, compounding curing agent and accelerator, and filling with AlN@BN core-shell filler.

[0077] The elastic modulus of the cured adhesive in the central region is ≥12 GPa, the coefficient of thermal expansion is ≤25 ppm / °C, and the thermal conductivity is ≥2.5 W / (m·K).

[0078] The edge region adhesive is prepared by using bisphenol A type epoxy resin and hydroxyl-terminated polydimethylsiloxane as the matrix, compounding a flexible curing agent, and filling it with polyurethane@silica core-shell elastic filler.

[0079] The transition region compound is made by blending the central region compound and the edge region compound in a spatial gradient ratio, wherein the volume fraction of the central region compound continuously decreases from 100% on the side adjacent to the central region to 0% on the side adjacent to the edge region.

[0080] The purpose of the transition zone compound is to eliminate abrupt changes in performance interfaces between the central and peripheral regions. By continuously and gradually varying key parameters such as modulus and coefficient of thermal expansion, new secondary stress concentration points caused by abrupt changes in material properties are avoided, ensuring the mechanical and thermal synergy and structural integrity of the entire bottom filler layer.

[0081] Example 1

[0082] A method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging, wherein the partitioned functionalized underfill adhesive is used for a 50mm×50mm AI chip, the method comprising the following steps:

[0083] Step S1: Using bisphenol F-naphthalene type epoxy resin as the matrix, a curing agent and an accelerator are compounded to construct a central region matrix mixture, and AlN@BN core-shell filler is filled in. After uniform dispersion, the central region adhesive is prepared.

[0084] Specifically, step S1 includes the following steps:

[0085] Step S11: Mix 100 parts by weight of bisphenol F-naphthalene type epoxy resin (EPON 862), 85 parts by weight of methyl hexahydrophthalic anhydride curing agent (MHHPA), and 0.5 parts by weight of 1-cyanoethyl-2-ethyl-4-methylimidazolium accelerator (2E4MZ-CN), and stir and disperse evenly at 60°C to obtain a central region matrix mixture.

[0086] Step S12: Using AlN (aluminum nitride) as the core and BN (boron nitride) as the shell, a BN layer is deposited on the AlN surface by chemical vapor deposition. Finally, the surface is treated with a silane coupling agent to obtain AlN@BN core-shell filler.

[0087] Step S13: Add 65 parts by weight of AlN@BN core-shell filler to the matrix mixture in the central region, place it in a planetary mixer, disperse it at 2000 rpm for 30 minutes, and then degas it under vacuum to obtain the central region compound.

[0088] The central region adhesive prepared by this step has a modulus of approximately 15 GPa, a CTE of approximately 22 ppm / °C, and a thermal conductivity of approximately 2.8 W / (m·K) after curing.

[0089] Step S2: Using bisphenol A type epoxy resin and hydroxyl-terminated polydimethylsiloxane as the matrix, a flexible curing agent is compounded to construct an epoxy-organosilicon interpenetrating network polymer, and polyurethane@silica core-shell elastic filler is filled to prepare the edge region adhesive.

[0090] Specifically, step S2 includes the following steps:

[0091] Step S21: Mix 70 parts by weight of bisphenol A type epoxy resin (E51), 30 parts by weight of hydroxyl-terminated polydimethylsiloxane (OH-PDMS, Mw=2000), and 35 parts by weight of amino silicone oil flexible curing agent (KF-8010) in proportion, and stir at 80°C for 1 hour to form an epoxy-organosilicon interpenetrating network polymer.

[0092] Step S22: Prepare a core-shell structure with polyurethane as the core and silica as the shell by emulsion polymerization or sol-gel method, and then perform surface treatment with silane coupling agent to obtain polyurethane@silica core-shell elastic filler.

[0093] Step S23: Add 40 parts by weight of polyurethane@silica core-shell elastic filler to the epoxy-organosilicon interpenetrating network polymer, disperse evenly and degas under vacuum to obtain the edge region adhesive.

[0094] After curing, the modulus of the adhesive in the edge area is approximately 1.5 GPa, the elongation at break is approximately 80%, and the CTE is approximately 38 ppm / °C.

[0095] Step S3: Based on the AI ​​chip partitioning design, perform partitioned adhesive application before bonding the AI ​​chip to the substrate.

[0096] Specifically, step S3 includes the following steps:

[0097] Step S31: Use a dual-cylinder dispensing device. Cylinder A is filled with adhesive for the central area, and cylinder B is filled with adhesive for the edge area.

[0098] Step S32: Based on the AI ​​chip, the substrate is partitioned into a central area, a transition area, and an edge area.

[0099] Specifically, the central region is a 20 mm × 20 mm square area at the center of the chip, extending 10 mm outwards from the center on all sides; the edge region is a ring-shaped area within 5 mm of the chip edge; and the transition region is a ring-shaped area with a width of 10 mm located between the central and edge regions.

[0100] Step S33: Before the AI ​​chip is bonded to the substrate, the dual-barrel dispensing equipment only outputs adhesive material to the central area.

[0101] Step S34: For the edge area, the dual-barrel dispensing equipment only outputs adhesive material for the edge area.

[0102] Step S35: For the transition area, the dual-barrel dispensing equipment dynamically adjusts the output ratio of the adhesive in the central area and the adhesive in the edge area according to the preset gradient mixing program, forming a continuous transition in space from 100% central area adhesive / 0% edge area adhesive to 0% central area adhesive / 100% edge area adhesive.

[0103] Specifically, step S35 includes the following steps:

[0104] Step S351: Add 0.5 wt% and 0.8 wt% fumed silica as thixotropic agents to the rubber compound in the central region and the rubber compound in the edge region, respectively, to achieve rheological control of the rubber compound.

[0105] By adding 0.5 wt% and 0.8 wt% fumed silica as thixotropic agents to the central and edge regions of the adhesive, the central and edge regions of the adhesive have similar viscosity curves and shear thinning characteristics at the dispensing temperature (50°C), thus avoiding phase separation or flow mismatch caused by differences in flowability during the mixing process.

[0106] Step S352: Connect a miniature static mixing tube (containing 12 mixing elements) to the rear end of the dispensing head of the dual-barrel dispensing equipment. During the dispensing process, the control system dynamically adjusts the injection volume flow rate of the adhesive in the central and edge regions according to a linear gradient, so that the mixing ratio of the adhesive in the central and edge regions gradually changes from 10:0 at the inner boundary (adjacent to the central region) to 0:10 at the outer boundary (adjacent to the edge region). The two adhesives are repeatedly divided and recombined in the static mixing tube, thereby achieving uniform blending at the microscale, and finally forming a transition layer with continuously varying modulus and coefficient of thermal expansion in the gap between the chip and the substrate.

[0107] Step S4: After dispensing, the AI ​​chip is mounted to obtain the package, and then a stepped temperature curing process is adopted: first, it is cured at 120°C for 1 hour, and then cured at 150°C for 2 hours to form a bottom filler adhesive layer with performance partitioning.

[0108] Performance Testing: The warpage of the packaged module was measured using a laser warpage meter, with a maximum warpage of 18 μm. A temperature cycling test was conducted from -55°C to 125°C for 1000 cycles. Afterward, observation using a scanning acoustic microscope (C-SAM) and cross-sectional sections revealed no delamination or cracks in the colloid or interface; the cracking rate was considered 0%. Under the same conditions, the control group using a commercially available homogeneous high-modulus underfill showed a warpage of 45 μm and an edge cracking rate of 8.5% after TC1000.

[0109] Example 2

[0110] A method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging, wherein the partitioned functionalized underfill adhesive is used for a 50mm×50mm AI chip, the method comprising the following steps:

[0111] Step S1: Using bisphenol F-naphthalene type epoxy resin as the matrix, a curing agent and an accelerator are compounded to construct a central region matrix mixture, and AlN@BN core-shell filler is filled in. After uniform dispersion, the central region adhesive is prepared.

[0112] Specifically, step S1 includes the following steps:

[0113] Step S11: Mix 100 parts by weight of bisphenol F-naphthalene type epoxy resin (EPON 862), 85 parts by weight of methyl hexahydrophthalic anhydride curing agent (MHHPA), and 0.5 parts by weight of 1-cyanoethyl-2-ethyl-4-methylimidazolium accelerator (2E4MZ-CN), and stir and disperse evenly at 60°C to obtain a central region matrix mixture.

[0114] Step S12: Using AlN (aluminum nitride) as the core and BN (boron nitride) as the shell, a BN layer is deposited on the surface of AlN by chemical vapor deposition, and finally the surface is treated with a silane coupling agent to obtain AlN@BN core-shell filler.

[0115] Step S13: Add 65 parts by weight of AlN@BN core-shell filler to the matrix mixture in the central region, place it in a planetary mixer, disperse it at 2000 rpm for 30 minutes, and then degas it under vacuum to obtain the central region compound.

[0116] The central region adhesive prepared by this step has a modulus of approximately 15 GPa, a CTE of approximately 22 ppm / °C, and a thermal conductivity of approximately 2.8 W / (m·K) after curing.

[0117] Step S2: Using bisphenol A type epoxy resin and hydroxyl-terminated polydimethylsiloxane as the matrix, a flexible curing agent is compounded to construct an epoxy-organosilicon interpenetrating network polymer, and polyurethane@silica core-shell elastic filler is filled to prepare the edge region adhesive.

[0118] Specifically, step S2 includes the following steps:

[0119] Step S21: Mix 70 parts by weight of bisphenol A type epoxy resin (E51), 30 parts by weight of hydroxyl-terminated polydimethylsiloxane (OH-PDMS, Mw=2000), and 35 parts by weight of amino silicone oil flexible curing agent (KF-8010) in proportion, and stir at 80°C for 1 hour to form an epoxy-organosilicon interpenetrating network polymer.

[0120] Step S22: Prepare a core-shell structure with polyurethane as the core and silica as the shell by emulsion polymerization or sol-gel method, and then perform surface treatment with silane coupling agent to obtain polyurethane@silica core-shell elastic filler.

[0121] Step S23: Add 40 parts by weight of polyurethane@silica core-shell elastic filler to the epoxy-organosilicon interpenetrating network polymer, disperse evenly and degas under vacuum to obtain the edge region adhesive.

[0122] After curing, the modulus of the adhesive in the edge area is approximately 1.5 GPa, the elongation at break is approximately 80%, and the CTE is approximately 38 ppm / °C.

[0123] Step S3: Based on the AI ​​chip partitioning design, perform partitioned adhesive application before bonding the AI ​​chip to the substrate.

[0124] Specifically, step S3 includes the following steps:

[0125] Step S31: Use a dual-cylinder dispensing device. Cylinder A is filled with adhesive for the central area, and cylinder B is filled with adhesive for the edge area.

[0126] Step S32: Based on the AI ​​chip, the substrate is partitioned into a central area, a transition area, and an edge area.

[0127] Specifically, the central region is a 20 mm × 20 mm square area at the center of the chip, extending 10 mm outwards from the center of the chip on all sides. The edge region is a ring-shaped area within 5 mm of the chip edge. The transition region is a ring-shaped area with a width of 10 mm in between.

[0128] Step S33: Before the AI ​​chip is bonded to the substrate, the dual-barrel dispensing equipment only outputs adhesive material to the central area.

[0129] Step S34: For the edge area, the dual-barrel dispensing equipment only outputs adhesive material for the edge area.

[0130] Step S35: For the transition area, the dual-barrel dispensing equipment dynamically adjusts the output ratio of the adhesive in the central area and the adhesive in the edge area according to the preset gradient mixing program, forming a continuous transition in space from 100% central area adhesive / 0% edge area adhesive to 0% central area adhesive / 100% edge area adhesive.

[0131] Specifically, step S35 is implemented in the following way:

[0132] In the transition region, a nonlinear gradient mixing strategy is adopted, meaning the volume fraction of the adhesive in the central region follows an S-shaped curve: smoothly decreasing from 100% at the inner boundary to 50% in the middle, and then smoothing to 0% at the outer boundary. This nonlinear gradient mixing strategy ensures that key performance parameters such as modulus and coefficient of thermal expansion exhibit a continuous distribution in the transition region, first changing slowly, then accelerating, and finally leveling off. Compared to a linear gradient, this further reduces the stress concentration factor at the interface, optimizing the long-term reliability of the encapsulation structure.

[0133] Step S4: After dispensing, the AI ​​chip is mounted, and then a stepped temperature curing process is used: first, it is cured at 120°C for 1 hour, and then cured at 150°C for 2 hours to form a performance-zoned bottom filler adhesive layer.

[0134] Performance testing: The maximum chip warpage was further reduced to 15 μm. The interface remained intact after 1500 temperature cycles. Finite element analysis showed that the stress concentration factor in the transition region was reduced by approximately 15% compared to the linear gradient in Example 1.

[0135] Example 3

[0136] A method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging, wherein the partitioned functionalized underfill adhesive is used for a 50mm×50mm AI chip, the method comprising the following steps:

[0137] Step S1: Using bisphenol F-naphthalene type epoxy resin as the matrix, a curing agent and an accelerator are compounded to construct a central region matrix mixture, and AlN@BN core-shell filler is filled in. After uniform dispersion, the central region adhesive is prepared.

[0138] Specifically, step S1 includes the following steps:

[0139] Step S11: Mix 100 parts by weight of bisphenol F-naphthalene type epoxy resin (EPON 862), 85 parts by weight of methyl hexahydrophthalic anhydride curing agent (MHHPA), and 0.5 parts by weight of 1-cyanoethyl-2-ethyl-4-methylimidazolium accelerator (2E4MZ-CN), and stir and disperse evenly at 60°C to obtain a central region matrix mixture.

[0140] Step S12: Using AlN (aluminum nitride) as the core and BN (boron nitride) as the shell, a BN layer is deposited on the surface of AlN by chemical vapor deposition, and finally the surface is treated with a silane coupling agent to obtain AlN@BN core-shell filler.

[0141] Step S13: Add 75 parts by weight of AlN@BN core-shell filler and 1 part by weight of spherical silica as a thixotropic agent to the matrix mixture in the central region. Place the mixture in a planetary mixer and disperse it at 2000 rpm for 30 minutes. Then degas it under vacuum to obtain the central region adhesive.

[0142] The spherical silica particles have a diameter of 0.5 μm. By adding spherical silica as a thixotropic agent, the rheological properties and shape retention of the adhesive in the central region on a smooth glass substrate are improved.

[0143] Step S2: Using bisphenol A type epoxy resin and hydroxyl-terminated polydimethylsiloxane as the matrix, a flexible curing agent is compounded to construct an epoxy-organosilicon interpenetrating network polymer, and polyurethane@silica core-shell elastic filler is filled to prepare the edge region adhesive.

[0144] Specifically, step S2 includes the following steps:

[0145] Step S21: Mix 70 parts by weight of bisphenol A type epoxy resin (E51), 30 parts by weight of hydroxyl-terminated polydimethylsiloxane (OH-PDMS, Mw=2000), and 35 parts by weight of amino silicone oil flexible curing agent (KF-8010) in proportion, and stir at 80°C for 1 hour to form an epoxy-organosilicon interpenetrating network polymer.

[0146] Step S22: Prepare a core-shell structure with polyurethane as the core and silica as the shell by emulsion polymerization or sol-gel method, and then perform surface treatment with silane coupling agent to obtain polyurethane@silica core-shell elastic filler.

[0147] Step S23: Add 40 parts by weight of polyurethane@silica core-shell elastic filler to the epoxy-organosilicon interpenetrating network polymer, disperse evenly and degas under vacuum to obtain the edge region adhesive.

[0148] After curing, the modulus of the adhesive in the edge area is approximately 1.5 GPa, the elongation at break is approximately 80%, and the CTE is approximately 38 ppm / °C.

[0149] Step S3: Based on the AI ​​chip partitioning design, perform partitioned adhesive application before bonding the AI ​​chip to the substrate.

[0150] Specifically, step S3 includes the following steps:

[0151] Step S31: Use a dual-cylinder dispensing device. Cylinder A is filled with adhesive for the central area, and cylinder B is filled with adhesive for the edge area.

[0152] Step S32: Based on the AI ​​chip, the substrate is partitioned into a central area, a transition area, and an edge area.

[0153] Specifically, the central region is a 20 mm × 20 mm square area at the center of the chip, extending 10 mm outwards from the center of the chip on all sides. The edge region is a ring-shaped area 5 mm from the edge of the chip. The transition region is a ring-shaped area with a width of 10 mm in between.

[0154] Step S33: Before the AI ​​chip is bonded to the substrate, the dual-barrel dispensing equipment only outputs adhesive material to the central area.

[0155] Step S34: For the edge area, the dual-barrel dispensing equipment only outputs adhesive material for the edge area.

[0156] Step S35: For the transition area, the dual-barrel dispensing equipment dynamically adjusts the output ratio of the adhesive in the central area and the adhesive in the edge area according to the preset gradient mixing program, forming a continuous transition in space from 100% central area adhesive / 0% edge area adhesive to 0% central area adhesive / 100% edge area adhesive.

[0157] Specifically, step S35 includes the following steps:

[0158] Step S351: Add 0.5 wt% and 0.8 wt% fumed silica as thixotropic agents to the rubber compound in the central region and the rubber compound in the edge region, respectively, to achieve rheological control of the rubber compound.

[0159] By adding 0.5 wt% and 0.8 wt% fumed silica as thixotropic agents to the central and edge regions of the adhesive, the central and edge regions of the adhesive have similar viscosity curves and shear thinning characteristics at the dispensing temperature (50°C), thus avoiding phase separation or flow mismatch caused by differences in flowability during the mixing process.

[0160] Step S352: Connect a miniature static mixing tube (containing 12 mixing elements) to the rear end of the dispensing head of the dual-barrel dispensing equipment. During the dispensing process, the control system dynamically adjusts the injection volume flow rate of the adhesive in the central and edge regions according to a linear gradient, so that the mixing ratio of the adhesive in the central and edge regions gradually changes from 10:0 at the inner boundary (adjacent to the central region) to 0:10 at the outer boundary (adjacent to the edge region). The two adhesives are repeatedly divided and recombined in the static mixing tube, thereby achieving uniform blending at the microscale, and finally forming a transition layer with continuously varying modulus and coefficient of thermal expansion in the gap between the chip and the substrate.

[0161] Step S4: After dispensing, the AI ​​chip is mounted, and then a stepped temperature curing process is used: first, it is cured at 120°C for 1 hour, and then cured at 150°C for 2 hours to form a performance-zoned bottom filler adhesive layer.

[0162] Performance testing: The AI ​​chip warpage is only 12 μm (contributed by the substrate's own stiffness). High temperature and humidity testing (85°C / 85%RH, 1000 hours) showed electrical performance parameter drift of less than 3%, demonstrating excellent long-term reliability.

[0163] Example 4

[0164] A method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging, wherein the partitioned functionalized underfill adhesive is used for a 50mm×50mm AI chip, the method comprising the following steps:

[0165] Step S1: Using bisphenol F-naphthalene type epoxy resin as the matrix, a curing agent and an accelerator are compounded to construct a central region matrix mixture, and AlN@BN core-shell filler is filled in. After uniform dispersion, the central region adhesive is prepared.

[0166] Specifically, step S1 includes the following steps:

[0167] Step S11: Mix 100 parts by weight of bisphenol F-naphthalene type epoxy resin (EPON 862), 85 parts by weight of methyl hexahydrophthalic anhydride curing agent (MHHPA), and 0.5 parts by weight of 1-cyanoethyl-2-ethyl-4-methylimidazolium accelerator (2E4MZ-CN), and stir and disperse evenly at 60°C to obtain a central region matrix mixture.

[0168] Step S12: Using AlN (aluminum nitride) as the core and BN (boron nitride) as the shell, a BN layer is deposited on the surface of AlN by chemical vapor deposition, and finally the surface is treated with a silane coupling agent to obtain AlN@BN core-shell filler.

[0169] Step S13: Add 65 parts by weight of AlN@BN core-shell filler to the matrix mixture in the central region, place it in a planetary mixer, disperse it at 2000 rpm for 30 minutes, and then degas it under vacuum to obtain the central region compound.

[0170] The central region adhesive prepared by this step has a modulus of approximately 15 GPa, a CTE of approximately 22 ppm / °C, and a thermal conductivity of approximately 2.8 W / (m·K) after curing.

[0171] Step S2: Using bisphenol A type epoxy resin and hydroxyl-terminated polydimethylsiloxane as the matrix, a flexible curing agent is compounded to construct an epoxy-organosilicon interpenetrating network polymer, and polyurethane@silica core-shell elastic filler is filled to prepare the edge region adhesive.

[0172] Specifically, step S2 includes the following steps:

[0173] Step S21: Mix 70 parts by weight of bisphenol A type epoxy resin (E51), 30 parts by weight of hydroxyl-terminated polydimethylsiloxane (OH-PDMS, Mw=2000), and 35 parts by weight of amino silicone oil flexible curing agent (KF-8010) in proportion, and stir at 80°C for 1 hour to form an epoxy-organosilicon interpenetrating network polymer.

[0174] Step S22: Prepare a core-shell structure with polyurethane as the core and silica as the shell by emulsion polymerization or sol-gel method, and then perform surface treatment with silane coupling agent to obtain polyurethane@silica core-shell elastic filler.

[0175] Step S23: Add 40 parts by weight of polyurethane@silica core-shell elastic filler to the epoxy-silica interpenetrating network polymer to prepare a masterbatch with a filler mass fraction of 60% (i.e., the polyurethane@silica core-shell elastic filler accounts for 60 wt% and the epoxy-silica interpenetrating network polymer accounts for 40 wt%). Disperse the masterbatch evenly in a planetary mixer and degas it under vacuum to obtain the edge region adhesive.

[0176] This method prepares the edge region compound, achieving a higher uniform dispersion of elastic filler content while maintaining the rheological properties suitable for dispensing. This results in an increase in the elongation at break of the final edge region compound to 95%, while maintaining the modulus at 1.8 GPa.

[0177] Step S3: Based on the AI ​​chip partitioning design, perform partitioned adhesive application before bonding the AI ​​chip to the substrate.

[0178] Specifically, step S3 includes the following steps:

[0179] Step S31: Use a dual-cylinder dispensing device. Cylinder A is filled with adhesive for the central area, and cylinder B is filled with adhesive for the edge area.

[0180] Step S32: Based on the AI ​​chip, the substrate is partitioned into a central area, a transition area, and an edge area.

[0181] Specifically, the central region is a 20 mm × 20 mm square area at the center of the chip, extending 10 mm outwards from the center of the chip on all sides; the edge region is a ring-shaped area within 5 mm of the chip edge; the transition region is in between the two, and the central ring-shaped area is 10 mm wide.

[0182] Step S33: Before the AI ​​chip is bonded to the substrate, the dual-barrel dispensing equipment only outputs adhesive material to the central area.

[0183] Step S34: For the edge area, the dual-barrel dispensing equipment only outputs adhesive material for the edge area.

[0184] Step S35: For the transition area, the dual-barrel dispensing equipment dynamically adjusts the output ratio of the adhesive in the central area and the adhesive in the edge area according to the preset gradient mixing program, forming a continuous transition in space from 100% central area adhesive / 0% edge area adhesive to 0% central area adhesive / 100% edge area adhesive.

[0185] Specifically, step S35 includes the following steps:

[0186] Step S351: Add 0.5 wt% and 0.8 wt% fumed silica as thixotropic agents to the rubber compound in the central region and the rubber compound in the edge region, respectively, to achieve rheological control of the rubber compound.

[0187] By adding 0.5 wt% and 0.8 wt% fumed silica as thixotropic agents to the central and edge regions of the adhesive, the central and edge regions of the adhesive have similar viscosity curves and shear thinning characteristics at the dispensing temperature (50°C), thus avoiding phase separation or flow mismatch caused by differences in flowability during the mixing process.

[0188] Step S352: Connect a miniature static mixing tube (containing 12 mixing elements) to the rear end of the dispensing head of the dual-barrel dispensing equipment. During the dispensing process, the control system dynamically adjusts the injection volume flow rate of the adhesive in the central region and the adhesive in the edge region according to a linear gradient. This causes the mixing ratio of the adhesive in the central region and the adhesive in the edge region to gradually change from 10:0 in the inner boundary (adjacent to the central region) to 0:10 in the outer boundary (adjacent to the edge region). The two adhesives are repeatedly divided and recombined in the static mixing tube, thereby achieving uniform blending at the microscale. Finally, a transition layer with continuously varying modulus and coefficient of thermal expansion is formed in the gap between the chip and the substrate.

[0189] Step S4: After dispensing, the AI ​​chip is mounted to obtain the package, and then a stepped temperature curing process is used: first cured at 120°C for 1 hour, then cured at 150°C for 2 hours, forming a performance-zoned bottom filler layer. Performance testing: After mechanical shock testing (1500G, 0.5 ms), the package showed no damage, exhibiting extremely high resistance to mechanical shock.

[0190] Parameter optimization and performance verification

[0191] Based on the principles of composite material micromechanics, this invention further reveals the control mechanism of partitioned functional design:

[0192] Modulus of the core region of the compound (E) c ) and thermal conductivity (λ) c The volume fraction (V) of AlN@BN filler varies with the amount of filler. f The relationship exhibits a nonlinear enhancement. To simultaneously satisfy the central region's requirement for high rigidity (E... c ≥12 GPa) and high thermal conductivity (λ) c To achieve the requirement of ≥2.5 W / (m·K), the AlN@BN filler content needs to be controlled within a reasonable threshold range. Experimental results show that when the volume fraction of AlN@BN filler is in the range of 50%-65% (corresponding to approximately 50-75 parts by weight), the aforementioned mechanical and thermal properties can be synergistically optimized while maintaining the rheological properties suitable for dispensing.

[0193] For edge regions, their stress buffering capacity primarily depends on the intrinsic flexibility of the adhesive material. The design goal is to enable the adhesive material in the edge regions to effectively release concentrated edge stress through its own deformation when the chip warps or deforms. According to the finite element simulation analysis of the packaging structure, when the elastic modulus of the adhesive material in the edge regions is ≤2 GPa and the elongation at break is ≥60%, compared with traditional homogeneous high-modulus underfill, the peak stress at the chip edge can be reduced by 40%-60%, thereby significantly delaying the initiation and spread of interface delamination.

[0194] The parameter optimization of the central region and the edge region is not carried out in isolation. The two achieve a smooth connection of performance through gradient design of the transition region, together forming a complete solution for spatial customization of mechanical and thermal performance.

[0195] The above design principles provide a theoretical basis for the optimal formulation of each embodiment of the present invention. Those skilled in the art can adjust the specific filler content and ratio under the guidance of the above principles according to the actual chip size, substrate type and reliability requirements.

[0196] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging, characterized in that, The method includes the following steps: Step S1: Using bisphenol F-naphthalene type epoxy resin as the matrix, a curing agent and an accelerator are compounded to construct a central region matrix mixture, and AlN@BN core-shell filler is filled in. After being dispersed evenly, the central region adhesive is prepared. Step S2: Using bisphenol A type epoxy resin and hydroxyl-terminated polydimethylsiloxane as the matrix, a flexible curing agent is compounded to construct an epoxy-organosilicon interpenetrating network polymer, and polyurethane@silica core-shell elastic filler is filled to prepare the edge region adhesive. Step S3: According to the AI ​​chip partitioning design, perform partitioned adhesive application before bonding the AI ​​chip to the substrate; Step S4: After dispensing, the AI ​​chip is mounted, and then a stepped temperature curing process is used: first, it is cured at 120°C for 1 hour, and then cured at 150°C for 2 hours to form a performance-zoned bottom filler adhesive layer.

2. The method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging according to claim 1, characterized in that, Step S1 includes the following steps: Step S11: Mix 100 parts by weight of bisphenol F-naphthalene type epoxy resin, 85 parts by weight of methyl hexahydrophthalic anhydride curing agent, and 0.5 parts by weight of 1-cyanoethyl-2-ethyl-4-methylimidazolium accelerator, and stir and disperse evenly at 60°C to obtain a central region matrix mixture. Step S12: Using AlN as the core and BN as the shell, a BN layer is coated on the surface of AlN by chemical vapor deposition, and finally the surface is treated with silane coupling agent to obtain AlN@BN core-shell filler; Step S13: Add AlN@BN core-shell filler to the matrix mixture in the central region, place it in a planetary mixer, disperse it at 2000 rpm for 30 minutes, and then degas it under vacuum to obtain the central region compound.

3. The method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging according to claim 2, characterized in that, In step S13, the amount of AlN@BN core-shell packing added is 50-75 parts by weight.

4. The method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging according to claim 1, characterized in that, Step S2 includes the following steps: Step S21: Mix 70 parts by weight of bisphenol A type epoxy resin, 30 parts by weight of hydroxyl-terminated polydimethylsiloxane, and 35 parts by weight of amino silicone oil flexible curing agent, and stir at 80°C for 1 hour to form an epoxy-organosilicon interpenetrating network polymer. Step S22: Prepare a core-shell structure with polyurethane as the core and silica as the shell by emulsion polymerization or sol-gel method, and then perform surface treatment with silane coupling agent to obtain polyurethane@silica core-shell elastic filler. Step S23: Add polyurethane@silica core-shell elastic filler to the epoxy-organosilicon interpenetrating network polymer, disperse evenly and degas under vacuum to obtain the edge region adhesive.

5. The method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging according to claim 4, characterized in that, The amount of polyurethane@silica core-shell elastic filler added in step S23 is 30-50 parts by weight.

6. The method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging according to claim 1, characterized in that, Step S3 includes the following steps: Step S31: Use a dual-cylinder dispensing device, with cylinder A filled with adhesive for the central area and cylinder B filled with adhesive for the edge area; Step S32: Based on the AI ​​chip, the substrate is partitioned into a central region, a transition region, and an edge region. Step S33: Before the AI ​​chip is bonded to the substrate, for the central area, the dual-barrel dispensing equipment only outputs adhesive for the central area; Step S34: For the edge area, the dual-barrel dispensing equipment only outputs adhesive material from the edge area; Step S35: For the transition area, the dual-barrel dispensing equipment dynamically adjusts the output ratio of the adhesive in the central area and the adhesive in the edge area according to the preset gradient mixing program, forming a continuous transition in space from 100% central area adhesive / 0% edge area adhesive to 0% central area adhesive / 100% edge area adhesive.

7. The method for preparing partitioned functionalized underfill adhesive for large-area AI chip packaging according to claim 4, characterized in that, The preset gradient mixing program in step S35 is a function of the mixing ratio of the adhesive in the central area and the adhesive in the edge area as a function of the dispensing position. During the dispensing process, the control system adjusts the flow ratio of the two injection pumps in the dual-barrel dispensing equipment in real time according to the preset gradient curve, so that the mixing ratio changes continuously in the transition area.

8. A partitioned functionalized underfill adhesive for large-area AI chip packaging, characterized in that, The partitioned functionalized bottom filler is prepared by the method described in any one of claims 1-7, and the partitioned functionalized bottom filler is divided into a central region, a transition region and an edge region from the inside to the outside.

9. The partitioned functionalized underfill adhesive for large-area AI chip packaging according to claim 8, characterized in that, The formulation of the zoned functionalized underfill adhesive exhibits a differentiated distribution in the central, transition, and edge regions: The central region adhesive is prepared by using bisphenol F-naphthalene type epoxy resin as the matrix, compounding curing agent and accelerator, and filling with AlN@BN core-shell filler; The edge region adhesive is prepared by using bisphenol A type epoxy resin and hydroxyl-terminated polydimethylsiloxane as the matrix, compounding a flexible curing agent, and filling with polyurethane@silica core-shell elastic filler; The transition region compound is made by blending the central region compound and the edge region compound in a spatial gradient ratio, wherein the volume fraction of the central region compound continuously decreases from 100% on the side adjacent to the central region to 0% on the side adjacent to the edge region.

Images