A semiconductor encapsulation adhesive film and a preparation process thereof

Abstract

This invention discloses a semiconductor packaging film and its preparation process. The film comprises, from top to bottom, a first adhesive layer, a thermally conductive resin layer, and a second adhesive layer. Monodisperse supported microspheres with reactive shells are dispersed in the thermally conductive resin layer. The microspheres are oriented and spread in a single layer and form covalent bonds with the resin during curing, giving the film high peel strength, excellent damp heat reliability, and high thermal conductivity. This invention is suitable for packaging heat dissipation and interface fixation of high-power chips.

Description

Technical Field

[0001] This invention relates to the technical field of encapsulant films for semiconductor packaging, and in particular to an encapsulant film for semiconductor packaging and its preparation process. Background Technology

[0002] With the rapid development of 5G, artificial intelligence, third-generation semiconductors, and high-density heterogeneous integration technology, semiconductor packaging is evolving towards ultra-thinness (wafer thickness is generally less than 50μm), high power density (single-chip heat flux density greater than 100 W / cm²), and multi-chip vertical stacking (8~16 layers or even 32 layers). Traditional liquid wafer bonding adhesives are no longer suitable for these scenarios due to adhesive overflow, voids, and uncontrolled bonding layer thickness. In contrast, die attach film (DAF) has become the mainstream bonding material for advanced packaging due to its excellent thickness uniformity, ability to apply multiple layers in a single pass, and high compatibility with wafer thinning-laser dicing-expansion processes. To simultaneously ensure high thermal conductivity and horizontal accuracy during chip attachment, DAF films in recent years have generally introduced monodisperse rigid support microspheres or spacers into the thermally conductive resin layer to achieve precise locking of bonding thickness and prevent excessive deformation or microcracks in ultra-thin chips under attachment pressure.

[0003] Chinese patent (CN116656247A) discloses a DAF film for semiconductor packaging and its preparation process. The core of this process involves uniformly embedding a large number of monodisperse rigid support microspheres within a thermally conductive resin layer, forming a "sandwich" structure. The support microspheres use addition-cure silicone rubber as a matrix, with two types of complexly modified functional fillers loaded onto their surfaces via electrostatic adsorption. After freeze-drying and high-pressure molding, they are physically laid flat in a thermally conductive resin solution to form a composite film. This simultaneously achieves improved chip adhesion level, thermal conductivity, and anti-aging performance. However, in existing technologies, support microspheres are typically prepared intact first, then physically dispersed or laid flat in a semi-cured thermally conductive resin solution. Ultimately, they rely solely on van der Waals forces and mechanical interlocking to bond with the surrounding resin matrix, forming a typical physical embedding interface. Due to the extremely low surface energy of commonly used silicone rubber or organic-inorganic hybrid microspheres, their poor wettability with polar thermally conductive resins such as epoxy, acrylic, or polyurethane leads to significant shear stress at the microsphere-resin interface during curing at 175–185°C and subsequent reflow soldering at temperatures above 260°C. This severe mismatch in thermal expansion coefficients causes interface debonding. Under high humidity and heat aging conditions such as 85°C / 85%RH, moisture rapidly penetrates along the weak interface, further inducing localized resin hydrolysis, swelling around the microspheres, and overall or partial detachment of the microspheres. Macroscopically, this manifests as blistering, delamination, and chip misalignment within the DAF film. These failure modes are particularly prominent in high-stack memory, automotive-grade SiC / GaN power modules, and fan-out panel-level packaging, and have become a core bottleneck restricting the reliability of existing DAF films containing support microspheres. Although existing technologies attempt to enhance the support effect by increasing the surface roughness of microspheres or increasing the filler loading, they often further exacerbate the stress concentration at the interface, thereby reducing the long-term adhesion strength and structural integrity under high temperature and high humidity conditions, making it difficult to fundamentally solve the intrinsic instability of the physical inlay interface under complex service conditions. Summary of the Invention

[0004] This application provides a semiconductor encapsulation film, which comprises, from top to bottom, a first adhesive layer, a thermally conductive resin layer, and a second adhesive layer. The thermally conductive resin layer contains a plurality of monodisperse support microspheres uniformly distributed therein. The support microspheres are core-shell structured microspheres, with the core being an elastic polyurea-urethane microsphere core and the shell being an organosilane shell containing reactive functional groups that can chemically crosslink with the thermally conductive resin layer. The shell and the thermally conductive resin layer form a chemically integrated interpenetrating network structure through covalent bonds.

[0005] It should be noted that the surface of the core of the elastic polyurea-urethane microspheres is rich in high-density urea bonds and residual amino groups. During the later stage of emulsion interfacial polymerization, a dense organosilane shell with uniform thickness and rich in epoxy or mercapto groups is grown in situ through hydrolysis-condensation of organosilane coupling agents or click reaction of mercapto-alkene. When the film is cured at 120-150℃, the reactive functional groups of this shell undergo covalent cross-linking with the thermally conductive resin to form a strong chemical bond interface. At the same time, the strong hydrogen bond network generated by the large number of urea bonds inside the polyurea-urethane core further constructs supramolecular physical cross-linking with the resin matrix, and together with the chemical covalent bonds, they form an interpenetrating network structure of "chemical-supramolecular dual locking", thereby completely blocking the water vapor penetration path along the interface and greatly alleviating the shear stress caused by the mismatch of thermal expansion coefficients.

[0006] As a preferred technical solution for semiconductor encapsulation films, the core of the elastic polyurea-urethane microspheres is formed in situ by interfacial polymerization of polymethylene polyphenyl isocyanate and polyetheramine, and the density of urea bonds in the core is 2.8 to 6.5 mmol / g.

[0007] It should be noted that the microsphere core of this invention is formed in situ through rapid nucleophilic addition polymerization of polymethylene polyphenyl isocyanate (PAPI) and polyetheramine at the oil-water interface. First, highly reactive urea groups are generated. Subsequently, excess -NCO reacts with amino groups and trace amounts of water to form a high-density urea bond network (2.8–6.5 mmol / g), forming an elastic three-dimensional cross-linked structure rich in intermolecular and intramolecular hydrogen bonds. This urea bond density is much higher than the inert Si-O-Si chains of traditional silicone rubber cores, enabling the microsphere core to simultaneously possess extremely strong hydrogen bond synergy, excellent hydrolysis resistance, and supramolecular physical cross-linking ability with epoxy / acrylic resins. Simultaneously, the residual amino groups act as anchor points, ensuring subsequent in-situ covalent grafting of the organosilane shell, forming a dual-locking interface of "chemical covalent + supramolecular hydrogen bonds," completely blocking water vapor penetration and interface debonding under high temperature and humidity conditions at the molecular level.

[0008] As a preferred technical solution for semiconductor packaging films, the thermally conductive resin layer further contains 0.5 to 5.0 wt% imidazole latent catalyst, enabling the film to achieve in-situ chemical cross-linking between the shell reactive functional groups and the resin matrix at 120 to 150°C, while maintaining the B-stage state after 90 days of storage below 80°C.

[0009] It should be noted that the key to adding 0.5–5.0 wt% imidazole latent catalyst (such as 2-phenyl-4,5-dihydroxymethylimidazolium) to the thermally conductive resin layer is that: below 80°C, the imidazole nitrogen atoms are effectively shielded by hydrogen bonds / coordination bonds, the catalytic activity is completely suppressed, the epoxy or thiol groups in the shell do not crosslink with the resin matrix, and the film can stably maintain a B-stage semi-cured state for more than 90 days; when the patch is heated to 120–150°C, the shielding bonds dissociate rapidly, exposing highly active tertiary nitrogen sites, which efficiently catalyze epoxy ring-opening or thiol-alkene click reactions within 30–60 seconds, realizing in-situ covalent crosslinking between the supporting microsphere shell and the resin, transforming the physical embedding into a chemically integrated structure.

[0010] As a preferred technical solution for a semiconductor packaging film, the supporting microspheres are arranged in a single-layer hexagonal close-packed arrangement in a thermally conductive resin layer, and the ratio of the center distance between adjacent microspheres to the average particle size of the microspheres is 1.01 to 1.08.

[0011] It should be noted that the supporting microspheres are arranged in a single-layer hexagonal dense packing (the ratio of the center distance between adjacent microspheres to the average particle size is 1.01 to 1.08), which ensures that each microsphere has the most uniform distribution of support points, significantly reduces local stress concentration, and ensures that the chip is subjected to highly consistent stress under mounting pressure. This completely eliminates the failure modes caused by the random embedding of microspheres in existing technologies, such as uneven support, chip tilting, and displacement, bubbling, and delamination under high temperature and humidity conditions. It significantly improves the bonding accuracy and long-term service reliability of ultra-thin chips in high-stack memory and automotive-grade power devices, and achieves ultra-high uniformity and structural stability that cannot be achieved by existing technologies.

[0012] As a preferred technical solution for a semiconductor packaging adhesive film, the first adhesive layer and / or the second adhesive layer are polyimide release films whose surfaces have been treated with corona or plasma.

[0013] It should be noted that the first adhesive layer and / or the second adhesive layer use polyimide release films with corona or plasma treatment on the surface. This introduces active groups such as polar hydroxyl and carboxyl groups on the polyimide surface, allowing it to form appropriate hydrogen bonds with the thermally conductive resin layer. The peel force is precisely controlled within an extremely low range, thereby achieving clean peeling after wafer lamination without damaging the B-stage thermally conductive layer, automatic release of the release film without residue when picking up the chip, and avoiding film tearing or resin residue caused by excessive or insufficient release force in existing technologies. This significantly improves the yield and operational stability of the entire process of ultra-thin wafer thinning-DAF lamination-hidden cutting-expansion.

[0014] In addition, this application provides a method for preparing a semiconductor encapsulating film, comprising the following steps:

[0015] S1. Provides core-shell structured support microspheres with reactive functional groups on the surface that can react with thermally conductive resin;

[0016] S2. Apply a layer of incompletely cured thermally conductive resin composition onto the second adhesive layer;

[0017] S3. The core-shell structured supporting microspheres are uniformly spread in a single layer on the surface of the thermally conductive resin composition described in step S2;

[0018] S4. Cover the supporting microspheres with another layer of incompletely cured thermally conductive resin composition;

[0019] S5. After covering the first adhesive layer, it is cured at 120-150°C to allow the reactive functional groups in the shell to undergo an in-situ chemical crosslinking reaction with the thermally conductive resin composition, forming a chemically bonded integrated thermally conductive resin layer, thus obtaining the semiconductor encapsulation film.

[0020] It should be noted that the preparation method provided in this application includes: first, providing core-shell structured support microspheres with reactive functional groups such as epoxy or thiol groups on their surface; coating a layer of incompletely cured thermally conductive resin composition onto a second adhesive layer; uniformly spreading a monolayer of core-shell support microspheres on the resin surface; then covering with another layer of the same incompletely cured thermally conductive resin composition; finally covering with the first adhesive layer and heating to cure at 120–150°C, causing the reactive functional groups of the shell layer to undergo in-situ chemical cross-linking with the thermally conductive resin, forming a chemically bonded interpenetrating network thermally conductive resin layer. This method achieves covalent bonding between the support microspheres and the resin during the curing stage, completely eliminating the need for traditional physical embedding processes, enabling the adhesive film to maintain extremely high interfacial stability and structural integrity under high temperature and high humidity conditions, significantly improving bonding accuracy and long-term reliability.

[0021] As a preferred technical solution for the preparation method of a semiconductor encapsulation film, in step S1, the preparation of the core-shell structured support microspheres is as follows: polymethylene polyphenyl isocyanate is dissolved in ethyl acetate as an oil phase, and an O / W emulsion is formed with an aqueous phase containing polyetheramine under high-speed shear. Interfacial polymerization is first carried out at 45-65°C to form an elastic polyurea-urethane core. Subsequently, an organosilane coupling agent containing epoxy or mercapto groups is added dropwise to the emulsion. The coupling agent is hydrolyzed on the core surface and reacts in situ with residual amino or isocyanate groups to form a dense shell. After the reaction is completed, the emulsion is demulsified, washed with water multiple times, and vacuum dried to obtain the core-shell structured support microspheres.

[0022] It should be noted that after polymethylene polyphenyl isocyanate is dissolved in ethyl acetate, it undergoes instantaneous nucleophilic addition interfacial polymerization at the O / W emulsion droplet interface formed by high-speed shearing with polyetheramine in the aqueous phase. The isocyanate groups preferentially react with amino groups to rapidly generate a high-density urea bond network, forming an elastic polyurea-urethane microsphere core, while retaining a small amount of unreacted amino and isocyanate groups as active anchors. Subsequently, the added epoxy- or mercapto-containing organosilane coupling agent hydrolyzes on the core surface to generate silanol groups, which then undergo in-situ condensation or addition reactions with the residual amino or isocyanate groups, rapidly growing a dense organosilane shell with uniform thickness and rich in reactive functional groups that can be further crosslinked with thermally conductive resins. This achieves continuous chemical bonding from core to shell, transforming the microspheres from traditional inert physical fillers into active supports that can be chemically integrated with the resin matrix in situ. This completely solves the problem of high-temperature and high-humidity interface failure caused by the physical embedding of existing technologies at the molecular level.

[0023] This invention employs monodisperse supported microspheres with reactive shells, a latent imidazole catalytic system, and a single-layer directional spreading structure. This allows the thermally conductive resin layer to form stable chemical bonds and a uniform three-dimensional support network during curing, significantly improving the interfacial bonding strength, damp heat aging stability, and thermal conductivity of the film. Compared to control schemes without shells, catalysts, or randomly distributed microspheres, the film of this invention exhibits higher peel strength after curing, significantly improved retention after PCT accelerated aging, and is less prone to delamination due to moisture erosion or thermal stress. It also possesses a high and adjustable thermal conductivity, meeting the comprehensive requirements of high-reliability semiconductor packaging for bonding performance, long-term reliability, and heat dissipation. Attached Figure Description

[0024] Figure 1 The infrared spectrum of the core-shell structured supported microspheres prepared in step S1 of Example 1;

[0025] Figure 2 TGA curves of the materials prepared for Example 1 and Comparative Example 1. Detailed Implementation

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0027] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0028] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0029] Example

[0030] Example 1

[0031] This embodiment provides a method for preparing a semiconductor encapsulating film, comprising the following steps:

[0032] Step S1. Preparation of core-shell structured microspheres: 28.0 g of polymethylene polyphenyl isocyanate (PAPI PM-200) was dissolved in 120 g of ethyl acetate as the oil phase; 30.0 g of polyetheramine Jeffamine D230 (Huntsman) was dissolved in 380 g of deionized water + 2.0 g of polyvinyl alcohol (PVA-1788) to prepare the aqueous phase. The two phases were emulsified in a high-speed shear emulsifier at 10,000 rpm for 2 min to form an O / W emulsion. The emulsion was heated to 45 ℃ and stirred for 40 min to complete interfacial polymerization, forming an elastic polyurea-urethane microsphere core (measured urea bond density 2.8 mmol / g). The temperature was then lowered to 40 °C, and 12.0 g of γ-glycidyl etheroxypropyltrimethoxysilane, an epoxy-containing organosilane coupling agent, was added dropwise uniformly over 30 min. The reaction was continued for 60 min to allow the silane to hydrolyze on the core surface and react in situ with the residual amino / isocyanate groups to form a dense shell. After the reaction was completed, 1 g of 25 wt% ammonia solution was added to break the emulsion. The mixture was centrifuged at 5000 rpm for 10 min, washed three times with deionized water, and vacuum dried at 60 °C for 12 h to obtain core-shell structured supported microspheres with an epoxy-rich shell.

[0033] Step S2. Preparation of thermally conductive resin composition: Weigh 100 g of hydrogenated bisphenol A type epoxy resin HP7200 (DIC Japan), 140 g of spherical boron nitride PTX25 (Momentive), 0.5 wt% of imidazole latent catalyst 2-phenyl-4,5-dihydroxymethylimidazolium (2P4MHZ, Shikoku Kasei), and 0.8 g of γ-mercaptopropyltriethoxysilane. Mix them under vacuum at 25 °C for 30 min in a planetary stirrer to obtain a paste-like thermally conductive resin composition.

[0034] Step S3. Preparation of the encapsulant film for semiconductor packaging: A 50 μm thick polyimide release film with a corona-treated surface (surface tension ≥44 dyne / cm) is used as the second adhesive layer. A thermally conductive resin composition of the above single resin system is coated using a slit coater, with the wet film thickness precisely controlled at 32 μm. Immediately, an electrostatic air knife composite device (voltage 8 kV, air pressure 0.02 MPa) is used to uniformly spread the core-shell structured microspheres obtained in step S1 onto the wet film surface with a 95% coverage rate. Under the action of capillary force on the liquid surface, a hexagonal close-packed arrangement spontaneously forms within 3-5 seconds (the measured ratio of the center distance between adjacent microspheres to the average particle size is 1.08). Another layer of the same thermally conductive resin composition of the same single resin system is then slit-coated to fill the gaps. Another polyimide release film of the same specification with a plasma-treated surface is then covered as the first adhesive layer. It is first pre-baked at 80 ℃ for 30 s to set the shape, and then transferred to a 120 ℃ oven for heating for 90 seconds. The epoxy groups in the shell undergo an in-situ chemical crosslinking reaction with HP7200 resin under the action of a latent catalyst, forming a chemically bonded interpenetrating network thermally conductive resin layer, ultimately yielding a semiconductor packaging film with a total thickness of 72 μm that remains stable in the B-order state after 90 days of storage below 80 °C.

[0035] Example 2

[0036] Step S1. Preparation of core-shell structured microspheres: 32.0 g of polymethylene polyphenyl isocyanate (PAPI PM-200) was dissolved in 110 g of ethyl acetate as the oil phase; 35.0 g of polyetheramine Jeffamine T403 (Huntsman) was dissolved in 388 g of deionized water + 1.5 g of sodium dodecyl sulfate (SDS) to prepare the aqueous phase. The two phases were emulsified in a high-speed shear emulsifier at 10,000 rpm for 2 min to form an O / W emulsion. The mixture was heated to 50 ℃ and stirred at a constant temperature for 35 min to complete interfacial polymerization, forming an elastic polyurea-urethane microsphere core (measured urea bond density 4.0 mmol / g). Subsequently, the temperature was lowered to 55 ℃, and 15.0 g of γ-mercaptopropyltriethoxysilane, a mercapto-containing organosilane coupling agent, was uniformly added dropwise over 30 min. The reaction was continued for 50 min to allow the silane to hydrolyze on the core surface and react in situ with the residual amino / isocyanate groups to form a dense shell. After the reaction was completed, 1 g of 25% ammonia was added to break the emulsion, centrifuged at 5000 rpm for 10 min, washed three times with deionized water, and dried under vacuum at 60 ℃ for 12 h to obtain core-shell structured microspheres with a shell rich in thiol groups.

[0037] Step S2. Preparation of thermally conductive resin composition: Weigh 100g of bisphenol A type liquid epoxy resin DER331 (Dow), 160g of spherical boron nitride PTX60 (Momentive), 1.8 wt% of imidazole latent catalyst 2-phenyl-4,5-dihydroxymethylimidazolium (2P4MHZ, Shikoku Kasei), and 1.2g of γ-mercaptopropyltriethoxysilane. Mix them under vacuum at 25 ℃ for 30 min in a planetary stirrer to obtain a paste-like thermally conductive resin composition.

[0038] Step S3. Preparation of the encapsulant film for semiconductor packaging: A 50 μm thick polyimide release film with a plasma-treated surface (surface tension ≥ 46 dyne / cm) is used as the second adhesive layer. The above single resin system is coated using a slot coater, and the wet film thickness is precisely controlled to 40 μm. Immediately, the core-shell microspheres obtained in step S1 are uniformly spread on the wet film surface with a 96% coverage using an electrostatic air knife composite device (voltage 9 kV, air pressure 0.025 MPa). Under the action of capillary force on the liquid surface, a hexagonal close-packed arrangement is spontaneously formed within 4-6 seconds (the measured center distance / particle size ratio is 1.05). Another layer of the same single resin system is then slot-coated to fill the gaps. Another polyimide release film of the same specification with a corona-treated surface is then covered as the first adhesive layer. It is first pre-baked at 80 ℃ for 25 s to set the shape, and then transferred to a 135 ℃ oven for heating for 75 seconds. The thiol groups in the shell undergo an in-situ thiol-olefin click crosslinking reaction with DER331 under the action of a latent catalyst, forming a chemically bonded interpenetrating network thermally conductive resin layer. Finally, a semiconductor packaging film with a total thickness of 85 μm is obtained, which remains stable in the B-stage state after 100 days of storage below 80 °C.

[0039] Example 3

[0040] Step S1. Preparation of core-shell structured supported microspheres: 38.0 g of polymethylene polyphenyl isocyanate (PAPI PM-200) was dissolved in 100 g of ethyl acetate as the oil phase; 42.0 g of polyaspartic acid ester F420 (Covestro) was dissolved in 398 g of deionized water + 2.0 g of polyvinylpyrrolidone K30 (BASF) to prepare the aqueous phase. The two phases were emulsified in a high-speed shear emulsifier at 10,000 rpm for 2 min to form an O / W emulsion. The mixture was heated to 60 ℃ and stirred at a constant temperature for 30 min to complete interfacial polymerization, forming an elastic polyurea-urethane microsphere core (measured urea bond density 5.2 mmol / g). The temperature was then lowered to 55 °C, and 18.0 g of γ-mercaptopropyltriethoxysilane, a mercapto-containing organosilane coupling agent, was added dropwise uniformly over 30 min. The reaction was continued for 45 min to allow the silane to hydrolyze on the core surface and react in situ with residual amino / isocyanate groups to form a dense shell. After the reaction was completed, 1 g of 25% ammonia solution was added to break the emulsion. The mixture was centrifuged at 5000 rpm for 10 min, washed three times with deionized water, and dried under vacuum at 60 °C for 12 h to obtain core-shell structured supported microspheres with a vinyl-rich shell.

[0041] Step S2. Preparation of thermally conductive resin composition: Weigh 100 g of alicyclic epoxy resin CEL2021P (Daicel), 180 g of spherical boron nitride PTX25 and flake boron nitride PF-10 in a mass ratio of 7:3, 3.5 wt% of imidazole latent catalyst 2-phenyl-4,5-dihydroxymethylimidazolium, and 1.5 g of γ-mercaptopropyltriethoxysilane. Mix under vacuum at 25 °C for 30 min in a planetary stirrer to obtain a paste-like thermally conductive resin composition.

[0042] Step S3. Preparation of the encapsulant film for semiconductor packaging: A 50 μm thick polyimide release film with a plasma-treated surface (surface tension ≥ 46 dyne / cm) is used as the second adhesive layer. A thermally conductive resin composition of the above single resin system is coated using a slot coater, with the wet film thickness precisely controlled at 54 μm. Immediately, an electrostatic air knife composite device (voltage 10 kV, air pressure 0.03 MPa) is used to uniformly spread the core-shell structured microspheres obtained in step S1 onto the wet film surface with a 97% coverage rate. Under the capillary force of the liquid surface, a hexagonal close-packed arrangement spontaneously forms within 4 seconds (the measured ratio of the center distance between adjacent microspheres to the average particle size is 1.04). Another layer of the same single resin system is then slot-coated to fill the gaps. Another polyimide release film of the same specification with a corona-treated surface is then covered as the first adhesive layer. It is pre-baked at 80 ℃ for 20 s for setting, and then transferred to a 140 ℃ oven for heating for 60 seconds. s, so that the vinyl group in the shell and CEL2021P resin undergo in-situ mercapto-olefin / hydrosilane addition crosslinking reaction under the action of a latent catalyst, forming a chemically bonded interpenetrating network thermally conductive resin layer, and finally obtaining a semiconductor packaging film with a total thickness of 105 μm that remains stable in the B-stage state after 120 days of storage below 80 ℃.

[0043] Example 4

[0044] Step S1. Preparation of core-shell structured supported microspheres: 45.0 g of polymethylene polyphenyl isocyanate (PAPI PM-200) was dissolved in 90 g of ethyl acetate as the oil phase; 48.0 g of polyetheramine Jeffamine D2000 (Huntsman) was dissolved in 410 g of deionized water + 2.0 g of polyvinyl alcohol (PVA-1788) to prepare the aqueous phase. The two phases were emulsified in a high-speed shear emulsifier at 10,000 rpm for 2 min to form an O / W emulsion. The emulsion was heated to 65 ℃ and stirred for 25 min to complete interfacial polymerization, forming an elastic polyurea-urethane microsphere core (measured urea bond density 6.5 mmol / g). The temperature was then lowered to 60 °C, and 22.0 g of γ-glycidyl etheroxypropyltrimethoxysilane, an epoxy-containing organosilane coupling agent, was added dropwise uniformly over 30 min. The reaction was continued for 40 min to allow the silane to hydrolyze on the core surface and react in situ with residual amino / isocyanate groups to form a dense bifunctional shell. After the reaction was completed, 1 g of 25% ammonia solution was added to break the emulsion, and the mixture was centrifuged at 5000 rpm for 10 min, washed three times with deionized water, and vacuum dried at 60 °C for 12 h to obtain core-shell structured supported microspheres with a shell rich in both epoxy and thiol groups.

[0045] Step S2. Preparation of thermally conductive resin composition: Weigh 100 g of high-toughness bisphenol F type epoxy resin YDF-175 (Guodu Chemical), 220 g of spherical boron nitride PTX100 and spherical alumina DAW10 in a mass ratio of 6:4, 5.0 wt% of imidazole latent catalyst 2-phenyl-4,5-dihydroxymethylimidazolium (2P4MHZ, Shikoku Kasei), and 1.8 g of γ-glycidyl etheroxypropyltrimethoxysilane. Mix under vacuum at 25 °C for 30 min in a planetary stirrer to obtain a paste-like thermally conductive resin composition.

[0046] Step S3. Preparation of the encapsulant film for semiconductor packaging: A 50 μm thick polyimide release film with a plasma-treated surface (surface tension ≥ 48 dyne / cm) is used as the second adhesive layer. A single-resin thermally conductive resin composition is coated using a slot coater, with the wet film thickness precisely controlled to 70 μm. Immediately, a precision electrostatic air knife and a low-frequency vibration-assisted device (voltage 11 kV, air pressure 0.035 MPa, vibration frequency 15 Hz) are used to uniformly spread the core-shell structured microspheres obtained in step S1 onto the wet film surface with a 98% coverage rate. Under the combined action of liquid surface capillary force and vibration, a perfect hexagonal dense packing arrangement is achieved within 3 seconds (the measured ratio of the center distance between adjacent microspheres to the average particle size is 1.01). Another layer of the same single-resin system is then slot-coated to fill the gaps. Another polyimide release film of the same specification with a corona-treated surface is then covered as the first adhesive layer. It is pre-baked at 80°C for 15 seconds for setting, and then transferred to 150°C. Heating in an oven at ℃ for 45 s allows the epoxy and mercapto groups in the shell to undergo a rapid in-situ chemical crosslinking reaction with YDF-175 resin under the action of a high dose of latent catalyst, forming a chemically integrated interpenetrating network thermally conductive resin layer with ultra-high crosslinking density. Finally, a semiconductor packaging film with a total thickness of 135 μm is obtained, which remains stable in the B-stage state after being stored below 80 ℃ for 180 days.

[0047] Comparison Example

[0048] Compare with Example 1

[0049] Compared with Example 1, this comparative example omits the shell preparation step and uses pure elastic polyurea-urethane microspheres (without organosilane shells) physically laid flat in thermally conductive resin.

[0050] Step S1. Preparation of Supported Microspheres: 28.0 g of polymethylene polyphenyl isocyanate (PAPI PM-200) was dissolved in 120 g of ethyl acetate as the oil phase; 30.0 g of polyetheramine Jeffamine D230 (Huntsman) was dissolved in 380 g of deionized water + 2.0 g of polyvinyl alcohol (PVA-1788) to prepare the aqueous phase. The two phases were emulsified in a high-speed shear emulsifier at 10,000 rpm for 2 min to form an O / W emulsion. The mixture was heated to 45 ℃ and stirred at a constant temperature for 40 min to complete interfacial polymerization, forming elastic polyurea-urethane microspheres (measured urea bond density 2.8 mmol / g). After the reaction, 1 g of 25 wt% ammonia was added to break the emulsion, centrifuged at 5000 rpm for 10 min, washed three times with deionized water, and dried under vacuum at 60 ℃ for 12 h to obtain pure polyurea-urethane supported microspheres (without a shell).

[0051] Step S2. Preparation of thermally conductive resin composition: Weigh 100 g of hydrogenated bisphenol A type epoxy resin HP7200 (DIC Japan), 140 g of spherical boron nitride PTX25 (Momentive), 0.5 wt% of imidazole latent catalyst 2-phenyl-4,5-dihydroxymethylimidazolium (2P4MHZ, Shikoku Kasei), and 0.8 g of γ-mercaptopropyltriethoxysilane. Mix them under vacuum at 25 °C for 30 min in a planetary stirrer to obtain a paste-like thermally conductive resin composition.

[0052] Step S3. Preparation of the encapsulant film for semiconductor packaging: A 50 μm thick polyimide release film with a corona-treated surface (surface tension ≥44 dyne / cm) is used as the second adhesive layer. A single-resin thermally conductive resin composition is coated using a slot coater, with the wet film thickness precisely controlled at 32 μm. Immediately, an electrostatic air knife composite device (8 kV, 0.02 MPa) is used to uniformly spread the pure polyurea-urethane supported microspheres obtained in Step 1 onto the wet film surface with a 95% coverage rate. Under the capillary action of the liquid surface, a hexagonal close-packed arrangement spontaneously forms within 3–5 seconds (the measured ratio of the center distance between adjacent microspheres to the average particle size is 1.08). Another layer of the same single-resin thermally conductive resin composition is then slot-coated to fill the gaps. Another polyimide release film of the same specification with a plasma-treated surface is then covered as the first adhesive layer. It is pre-baked at 80 ℃ for 30 s for setting, and then transferred to a 120 ℃ oven for heating for 90 seconds. s, forming a physically embedded thermally conductive resin layer, ultimately yielding a semiconductor packaging film with a total thickness of 72 μm.

[0053] Compare with Example 2

[0054] This comparative example differs from Example 1 only in that the imidazole latent catalyst in the thermally conductive resin composition is omitted.

[0055] Step S1. Preparation of core-shell structured supported microspheres: 28.0 g of polymethylene polyphenyl isocyanate (PAPI PM-200) was dissolved in 120 g of ethyl acetate as the oil phase; 30.0 g of polyetheramine Jeffamine D230 (Huntsman) was dissolved in 380 g of deionized water + 2.0 g of polyvinyl alcohol (PVA-1788) to prepare the aqueous phase. The two phases were emulsified in a high-speed shear emulsifier at 10,000 rpm for 2 min to form an O / W emulsion. The emulsion was heated to 45 ℃ and stirred at a constant temperature for 40 min to complete interfacial polymerization, forming an elastic polyurea-urethane microsphere core (measured urea bond density 2.8 mmol / g). The temperature was then lowered to 40 °C, and 12.0 g of γ-glycidyl etheroxypropyltrimethoxysilane, an epoxy-containing organosilane coupling agent, was added dropwise uniformly over 30 min. The reaction was continued for 60 min to allow the silane to hydrolyze on the core surface and react in situ with the residual amino / isocyanate groups to form a dense shell. After the reaction was completed, 1 g of 25 wt% ammonia solution was added to break the emulsion. The mixture was centrifuged at 5000 rpm for 10 min, washed three times with deionized water, and vacuum dried at 60 °C for 12 h to obtain core-shell structured supported microspheres with an epoxy-rich shell.

[0056] Step S2. Preparation of thermally conductive resin composition: Weigh 100 g of hydrogenated bisphenol A type epoxy resin HP7200 (DIC Japan), 140 g of spherical boron nitride PTX25 (Momentive), and 0.8 g of γ-mercaptopropyltriethoxysilane. Mix them in a planetary stirrer at 25 °C under vacuum for 30 min to obtain a paste-like thermally conductive resin composition (without imidazole catalyst).

[0057] Step S3. Preparation of the encapsulant film for semiconductor packaging: A 50 μm thick polyimide release film with a corona-treated surface (surface tension ≥44 dyne / cm) is used as the second adhesive layer. A single-resin thermally conductive resin composition is coated using a slot coater, with the wet film thickness precisely controlled at 32 μm. Immediately, an electrostatic air knife composite device (8 kV, 0.02 MPa) is used to uniformly spread the core-shell structured microspheres obtained in Step 1 onto the wet film surface with a 95% coverage rate. Under the capillary action of the liquid surface, a hexagonal close-packed arrangement spontaneously forms within 3–5 seconds (the measured ratio of the center distance between adjacent microspheres to the average particle size is 1.08). Another layer of the same single-resin thermally conductive resin composition is then slot-coated to fill the gaps. Another polyimide release film of the same specification with a plasma-treated surface is then covered as the first adhesive layer. It is pre-baked at 80 °C for 30 s for setting, and then transferred to a 120 °C oven for heating for 90 seconds. The epoxy groups in the shell are cross-linked with HP7200 resin (without catalyst acceleration) to finally obtain a semiconductor encapsulation film with a total thickness of 72 μm.

[0058] Compare with Example 3

[0059] Compared with Example 1, this comparative example only changed the microsphere spreading method, using stirring dispersion instead of the electrostatic air knife composite device, resulting in random distribution of microspheres instead of single-layer hexagonal dense packing.

[0060] Step S1. Preparation of core-shell structured supported microspheres: 28.0 g of polymethylene polyphenyl isocyanate (PAPI PM-200) was dissolved in 120 g of ethyl acetate as the oil phase; 30.0 g of polyetheramine Jeffamine D230 (Huntsman) was dissolved in 380 g of deionized water + 2.0 g of polyvinyl alcohol (PVA-1788) to prepare the aqueous phase. The two phases were emulsified in a high-speed shear emulsifier at 10,000 rpm for 2 min to form an O / W emulsion. The emulsion was heated to 45 ℃ and stirred at a constant temperature for 40 min to complete interfacial polymerization, forming an elastic polyurea-urethane microsphere core (measured urea bond density 2.8 mmol / g). The temperature was then lowered to 40 °C, and 12.0 g of γ-glycidyl etheroxypropyltrimethoxysilane, an epoxy-containing organosilane coupling agent, was added dropwise uniformly over 30 min. The reaction was continued for 60 min to allow the silane to hydrolyze on the core surface and react in situ with the residual amino / isocyanate groups to form a dense shell. After the reaction was completed, 1 g of 25 wt% ammonia solution was added to break the emulsion. The mixture was centrifuged at 5000 rpm for 10 min, washed three times with deionized water, and vacuum dried at 60 °C for 12 h to obtain core-shell structured supported microspheres with an epoxy-rich shell.

[0061] Step S2. Preparation of thermally conductive resin composition: Weigh 100 g of hydrogenated bisphenol A type epoxy resin HP7200 (DIC Japan), 140 g of spherical boron nitride PTX25 (Momentive), 0.5 wt% of imidazole latent catalyst 2-phenyl-4,5-dihydroxymethylimidazolium (2P4MHZ, Shikoku Kasei), and 0.8 g of γ-mercaptopropyltriethoxysilane. Mix them under vacuum at 25 °C for 30 min in a planetary stirrer to obtain a paste-like thermally conductive resin composition.

[0062] Step S3. Preparation of the semiconductor packaging film: A 50 μm thick polyimide release film with a corona-treated surface (surface tension ≥44 dyne / cm) is used as the second adhesive layer. A thermally conductive resin composition of the above single resin system is coated using a slot coater, and the wet film thickness is precisely controlled to be 32 μm. The core-shell structure support microspheres obtained in step 1 are added to the wet film and uniformly dispersed by mechanical stirring (coverage of about 95%, but randomly distributed, not hexagonal dense packing). Another layer of thermally conductive resin composition of the same single resin system is then slot-coated to fill the gaps. Another polyimide release film of the same specification with a plasma-treated surface is covered as the first adhesive layer. It is first pre-baked at 80 ℃ for 30 s to set the shape, and then transferred to a 120 ℃ oven for 90 s to allow the epoxy groups in the shell layer to undergo an in-situ chemical cross-linking reaction with the HP7200 resin under the action of a latent catalyst, forming a chemically bonded interpenetrating network thermally conductive resin layer, and finally obtaining a semiconductor packaging film with a total thickness of 72 μm.

[0063] Compare with Example 4

[0064] This comparative example uses only untreated polyimide release film (without plasma treatment) compared to Example 1.

[0065] Step S1. Preparation of core-shell structured supported microspheres: 28.0 g of polymethylene polyphenyl isocyanate (PAPI PM-200) was dissolved in 120 g of ethyl acetate as the oil phase; 30.0 g of polyetheramine Jeffamine D230 (Huntsman) was dissolved in 380 g of deionized water + 2.0 g of polyvinyl alcohol (PVA-1788) to prepare the aqueous phase. The two phases were emulsified in a high-speed shear emulsifier at 10,000 rpm for 2 min to form an O / W emulsion. The emulsion was heated to 45 ℃ and stirred at a constant temperature for 40 min to complete interfacial polymerization, forming an elastic polyurea-urethane microsphere core (measured urea bond density 2.8 mmol / g). The temperature was then lowered to 40 °C, and 12.0 g of γ-glycidyl etheroxypropyltrimethoxysilane, an epoxy-containing organosilane coupling agent, was added dropwise uniformly over 30 min. The reaction was continued for 60 min to allow the silane to hydrolyze on the core surface and react in situ with the residual amino / isocyanate groups to form a dense shell. After the reaction was completed, 1 g of 25 wt% ammonia solution was added to break the emulsion. The mixture was centrifuged at 5000 rpm for 10 min, washed three times with deionized water, and vacuum dried at 60 °C for 12 h to obtain core-shell structured supported microspheres with an epoxy-rich shell.

[0066] Step S2. Preparation of thermally conductive resin composition: Weigh 100 g of hydrogenated bisphenol A type epoxy resin HP7200 (DIC Japan), 140 g of spherical boron nitride PTX25 (Momentive), 0.5 wt% of imidazole latent catalyst 2-phenyl-4,5-dihydroxymethylimidazolium (2P4MHZ, Shikoku Kasei), and 0.8 g of γ-mercaptopropyltriethoxysilane. Mix them under vacuum at 25 °C for 30 min in a planetary stirrer to obtain a paste-like thermally conductive resin composition.

[0067] Step S3. Preparation of the encapsulant film for semiconductor packaging: Take a 50 μm thick, untreated polyimide release film as the second adhesive layer. Coat the above-mentioned single-resin system thermally conductive resin composition with a slit coater, and precisely control the wet film thickness to 32 μm. Immediately use an electrostatic air knife composite device (voltage 8 kV, air pressure 0.02 MPa) to uniformly spread the core-shell structured microspheres obtained in step 1 on the wet film surface with a 95% coverage. Under the action of capillary force on the liquid surface, a hexagonal dense packing arrangement is spontaneously formed within 3-5 seconds (the measured ratio of the center distance between adjacent microspheres to the average particle size is 1.08). Then, slit coat another layer of the same single-resin system thermally conductive resin composition to fill the gaps. Cover with another untreated polyimide release film of the same specification as the first adhesive layer. Pre-bake at 80 ℃ for 30 s to set the shape, and then transfer to a 120 ℃ oven for heating for 90 seconds. The epoxy groups in the shell undergo an in-situ chemical cross-linking reaction with HP7200 resin under the action of a latent catalyst, forming a chemically bonded interpenetrating network thermally conductive resin layer, ultimately yielding a semiconductor packaging film with a total thickness of 72 μm.

[0068] Performance testing

[0069] The performance of the DAF samples provided in Examples 1-4 and Comparative Examples 1-4 was tested respectively, and the test data are recorded in the corresponding tables:

[0070] The testing method for DAF membranes is as follows:

[0071] 1. Peel force: The peel force of the steel plate or silicon wafer before and after curing is tested at 180° after being rolled at 60°C for 10 minutes, in accordance with GB / T 2792-2014.

[0072] 2. Aging test: The aging test experiment uses the high pressure accelerated aging (PCT) method, with conditions of 121℃ / 100%RH / 2atm for 96 hours (refer to JEDEC JESD22-A102).

[0073] 3. Thermal conductivity: The thermal conductivity was tested according to GB / T 22588-2008 standard.

[0074] Table 1

[0075]

[0076] In conjunction with Example 1 and Figure 1 It can be seen that 2270 cm -1 The extremely weak residual -NCO absorption peak at 1640 cm⁻¹ indicates that the interfacial polymerization reaction is extremely complete. -1 The strongest urea C=O stretching vibration peak across the entire spectrum was observed, confirming that the microsphere core formed a high-density urea bond cross-linking network (measured at 2.8 mmol / g), endowing the core with excellent elasticity and hydrogen bond synergistic ability; 1100 cm⁻¹ -1 and 1080 cm -1 Extremely broad and strong Si-O-Si asymmetric stretching vibration peaks appear, constituting the most prominent feature of the shell; 910 cm⁻¹ -1 The characteristic breathing vibration peaks of the epoxy ring have largely disappeared, indicating that the epoxy groups in KH-560 have undergone a high degree of ring-opening during the curing stage and have undergone in-situ chemical cross-linking with the thermally conductive resin; 3400 cm -1 Broad peak and 950 cm -1 The retained Si-OH signal further proves that the shell surface still has a suitable amount of active silanol groups, which can enhance the chemical bonding with the substrate; 800 cm -1 Si-C and 1000 cm -1 The faint residual alkoxy peak indicates that the silane polymerization is complete. The overall spectrum has a flat baseline, sharp peaks, and no obvious impurities, which fully verifies the continuous covalent connection from the elastic polyurea-urethane core to the reactive organosilane shell. This achieves chemical integration of the core-shell interface and completely solves the failure problem of traditional physically embedded microspheres under high temperature and high humidity conditions, which are prone to debonding and water vapor penetration. This provides direct spectroscopic evidence for the excellent interfacial stability and hydrothermal reliability of the film.

[0077] Combined with Example 1, Comparative Example 1, and Figure 2It can be seen that the TGA curves of Example 1 and Comparative Example 1 clearly reflect the decisive influence of the bonding mode between the supporting microspheres and the resin matrix on the thermal stability of the film. Example 1 exhibits typical three-stage weight loss characteristics under N2 atmosphere and 10℃ / min heating conditions: weight loss of about 8% at 100-220℃ (mainly due to the volatilization of adsorbed water and residual solvent), weight loss of about 12% at 230-380℃ (initial breakage of epoxy side chains and some urea bonds), main weight loss of about 55% at 400-600℃ (gradual carbonization of polyurea-urethane backbone, epoxy skeleton and organosilicon shell), and char residue of about 8wt% at 600℃. The weight loss rate of each stage is gradual and the transition is smooth. The initial decomposition temperature (5% weight loss) is about 285℃. Compared to Example 1, which uses pure polyurea-urethane microspheres without reactive shells, physically embedded only in the same resin system, its weight loss curve is significantly forward and steeper: the 5% weight loss temperature drops to approximately 165 °C, a sharp weight loss of about 20% occurs in the 180–340 °C range, the main weight loss is nearly 68% in the 320–550 °C range, and the char residue at 600 °C is only about 2 wt%. These differences indicate that the physically embedded interface becomes a rapid diffusion channel for pyrolysis molecules and pyrolysis products in the early stages of heating, leading to premature local resin degradation and inducing microcrack propagation, ultimately significantly reducing the overall thermal decomposition temperature and char residue. In contrast, Example 1, through in-situ covalent cross-linking of the shell reactive functional groups with the resin, forms a chemically integrated interpenetrating network structure, effectively blocking weak interfacial regions and substantially improving the overall thermal stability of the material. This result is consistent with the peel strength and PCT aging retention data, further verifying the necessity of reactive core-shell microsphere structures in improving the long-term reliability of semiconductor packaging films from a thermal analysis perspective.

[0078] As can be seen from Examples 1 to 4 and Table 1, the adhesive film of the present invention exhibits stable and excellent interfacial properties under different thicknesses and formulations. Its 180° peel strength after curing is in the range of 1.05–1.50 N / 25 mm, and after PCT aging (121℃ / 100%RH / 2 atm, 96 h), it still maintains 0.92–1.27 N / 25 mm, corresponding to a PCT retention rate of approximately 84.7%–87.6%. Simultaneously, its thermal conductivity gradually increases with the example number, ranging from 1.80 to 2.60 W·m. -1 ·K -1 The scope of this trend fully demonstrates that the present invention, through the synergistic effect of core-shell structured microspheres, a latent imidazole catalytic system, and a monolayer uniformly spreadable structure, enables the film to achieve excellent and controllable comprehensive performance in terms of curing strength, hygrothermal stability, and thermal conductivity.

[0079] As can be seen from Example 1, Comparative Example 1, and Table 1, the peel force of both before curing was approximately 0.50 N / 25 mm. However, after curing, the peel force of Example 1 increased to 1.05 N / 25 mm, while that of Comparative Example 1 was only 0.78 N / 25 mm. After PCT aging for 96 h, Example 1 still maintained 0.92 N / 25 mm (retention rate 87.6%), while that of Comparative Example 1 decreased to only 0.32 N / 25 mm (retention rate only 41.0%). This significant difference indicates that the microspheres of Comparative Example 1 lack a reactive shell and only form a physical interlocking structure, making the interface susceptible to moisture erosion under humid and hot conditions. In contrast, the core-shell structure microspheres of Example 1 can form covalent bonds with the resin during curing, thereby significantly improving interface stability and maintaining high humid and hot reliability.

[0080] Combining Example 1, Comparative Example 2, and Table 1, it can be seen that although Comparative Example 2 also used core-shell structured microspheres, the curing reaction was insufficient due to the absence of an imidazole latent catalyst. Its peel strength after curing was only 0.95 N / 25 mm, significantly lower than the 1.05 N / 25 mm of Example 1. After PCT aging for 96 h, the peel strength of Comparative Example 2 decreased to 0.70 N / 25 mm (retention rate 73.7%), still significantly lower than the 87.6% of Example 1. The results indicate that the imidazole catalyst plays a crucial role in promoting the crosslinking reaction between the epoxy and shell layers, making the interface structure denser and more stable, thereby achieving a higher retention rate during humid heat aging.

[0081] Combining Example 1, Comparative Example 3, and Table 1, it can be seen that, due to the random distribution of microspheres in the resin, the peel force of Comparative Example 3 after curing is only 0.82 N / 25 mm, significantly lower than the 1.05 N / 25 mm of Example 1. After PCT, the peel force of Comparative Example 3 further decreased to 0.49 N / 25 mm (retention rate 59.8%), still far lower than the 87.6% of Example 1. This difference indicates that, due to the lack of a single-layer oriented spreading structure, the inconsistent local support height in Comparative Example 3 leads to interface stress concentration, making it more prone to path-type interface failure under humid and hot environments. In contrast, the single-layer hexagonal densest arrangement achieved by the electrostatic air knife in Example 1 can form a uniform support structure, thereby significantly improving interface reliability.

[0082] As can be seen from Example 1, Comparative Example 4, and Table 1, the peel force of Comparative Example 4 after curing was only 0.88 N / 25 mm, significantly lower than that of Example 1 (1.05 N / 25 mm), because the PI release film was not subjected to plasma surface treatment. After PCT aging, the peel force of Comparative Example 4 was 0.52 N / 25 mm (retention rate 59.8%), still far lower than that of Example 1 (87.6%). This indicates that insufficient surface energy of the release film will affect the bonding integrity of the cured interface, making it prone to interfacial delamination in humid and hot environments. In contrast, the treated PI release film used in Example 1 significantly improved the interfacial adhesion, resulting in a significant improvement in overall interfacial stability and humid and hot retention performance.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A semiconductor encapsulation film, characterized in that, The adhesive film comprises, from top to bottom, a first adhesive layer, a thermally conductive resin layer, and a second adhesive layer. The thermally conductive resin layer contains a plurality of monodisperse support microspheres, which are core-shell structured microspheres. The core is an elastic polyurea-urethane microsphere core, and the shell is an organosilane shell containing reactive functional groups that can chemically crosslink with the thermally conductive resin layer. The reactive functional groups are epoxy groups or thiol groups. The shell and the thermally conductive resin layer form a chemically integrated interpenetrating network structure through covalent bonds. The core of the elastic polyurea-urethane microspheres is formed in situ by interfacial polymerization of polymethylene polyphenyl isocyanate and polyetheramine, and the density of urea bonds in the core is 2.8–6.5 mmol / g; The thermally conductive resin layer further contains 0.5 to 5.0 wt% imidazole latent catalyst, which enables the film to achieve in-situ chemical cross-linking between the shell reactive functional groups and the resin matrix at 120 to 150°C, and maintains the B-stage state after being stored at below 80°C for 90 days. The supporting microspheres are arranged in a single-layer hexagonal close-packed arrangement in the thermally conductive resin layer, and the ratio of the center distance between adjacent microspheres to the average particle size of the microspheres is 1.01 to 1.

08.

2. The semiconductor encapsulating film according to claim 1, characterized in that, The first adhesive layer and / or the second adhesive layer are polyimide release films whose surfaces have been treated with corona or plasma.

3. A method for preparing the semiconductor encapsulating film according to claim 1, characterized in that, Includes the following steps: S1. Provides core-shell structured support microspheres with reactive functional groups on the surface that can react with thermally conductive resin; S2. Apply a layer of incompletely cured thermally conductive resin composition onto the second adhesive layer; S3. The core-shell structured supporting microspheres are uniformly spread in a single layer on the surface of the thermally conductive resin composition described in step S2; S4. Cover the supporting microspheres with another layer of incompletely cured thermally conductive resin composition; S5. After covering the first adhesive layer, it is cured at 120-150°C to allow the reactive functional groups in the shell to undergo an in-situ chemical crosslinking reaction with the thermally conductive resin composition, forming a chemically bonded integrated thermally conductive resin layer, thus obtaining the semiconductor encapsulation film.

4. The preparation method according to claim 3, characterized in that, In step S1, the preparation method of the core-shell structured support microspheres is as follows: polymethylene polyphenyl isocyanate is dissolved in ethyl acetate as an oil phase, and an O / W emulsion is formed with an aqueous phase containing polyetheramine under high-speed shear. Interfacial polymerization is first carried out at 45-65°C to form an elastic polyurea-urethane core. Then, an organosilane coupling agent is added dropwise to the emulsion. The coupling agent is hydrolyzed on the core surface and reacts in situ with residual amino or isocyanate groups to form a dense shell. After the reaction is completed, the emulsion is demulsified, washed with water multiple times, and vacuum dried to obtain the core-shell structured support microspheres.

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