High-adhesion epoxy resin composition and application thereof in semiconductor chip packaging

Abstract

The invention relates to the technical field of epoxy resin materials, in particular to a high-adhesion epoxy resin composition and application thereof in semiconductor chip packaging. The photoresponsive epoxy resin composition comprises photoresponsive modified anhydride, a nano composite filler, a photothermal dual-response accelerator, an interface modification coupling agent, an efficient release agent and heterocyclic epoxy resin. According to the invention, by introducing the photoresponsive modified anhydride grafted with photosensitive groups and the core-shell structure nano-composite filler coated with the near-infrared light absorption dye layer on the surface, and cooperating with the microencapsulated photothermal dual-response accelerator, the composition has the advantages that after an optical semiconductor chip is packaged, the photoresponse property of the composition is greatly improved; the light of a specific wave band generated by working of the chip can be utilized to trigger rearrangement and microstructure optimization of a curing network, and meanwhile, through the photo-thermal conversion synergistic effect of the nano composite filler, the comprehensive improvement of the linear expansion coefficient, the heat-conducting property, the aging resistance and the bonding strength is realized on the premise of keeping high light transmission.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin materials technology, and more specifically, to high-adhesion epoxy resin compositions and their application in semiconductor chip packaging. Background Technology

[0002] Epoxy resin materials are thermosetting polymer composites made by adding curing agents, fillers, and various functional additives to epoxy resin as the matrix. The epoxy groups in its molecular structure undergo a cross-linking reaction under the action of the curing agent, forming a three-dimensional network structure, which endows the material with excellent thermal stability, mechanical strength, and chemical resistance.

[0003] In the field of semiconductor chip packaging, epoxy resin is mainly used in the form of epoxy molding compound. It forms a protective layer through molding process, which can not only fix the connection between the chip and the substrate, but also precisely control the curing temperature, shrinkage rate and dielectric properties of the material by adjusting the ratio of fillers and additives, thereby meeting the packaging requirements of the chip in high temperature, high pressure or corrosive environment.

[0004] However, with the rapid development of optoelectronic integration technology and high-power chips, the packaging environment poses more stringent challenges to the optical properties, thermomechanical reliability, and long-term stability of materials. In the fields of optical sensors and opto-semiconductor packaging, in order to achieve precise control of light in specific wavelength bands, functional fillers are often introduced into the resin matrix to achieve functions such as infrared cutoff. However, in existing technologies, inorganic fillers and epoxy resin matrices have problems such as large differences in refractive index and poor interfacial compatibility, which not only affect the uniformity of filler dispersion and completeness of function, but also cause transmittance loss due to light scattering. If fillers are avoided to maintain transparency, the linear expansion coefficient of the material will be too high, far exceeding the glass transition temperature in high-temperature processes, causing reliability problems such as delamination between the package and the chip or lead frame, and gold wire breakage. At the same time, insufficient thermal conductivity also exacerbates the risk of light decay caused by heat accumulation.

[0005] In addition, some solutions attempt to introduce colorants to solve light interference, but these small molecules are prone to migration, degradation or discoloration under high temperature and humidity or long-term light irradiation, which leads to drift in device optical parameters and makes it difficult to guarantee aging resistance. Summary of the Invention

[0006] The purpose of this invention is to solve the problem that existing epoxy resin compositions for optical semiconductor packaging are difficult to balance between infrared cutoff efficiency and light transmittance, and have deficiencies in terms of linear expansion coefficient, thermal conductivity, aging resistance and adhesive strength, which cannot meet the high light transmittance and high reliability packaging requirements of high-sensitivity optical sensors and highly integrated chips.

[0007] The purpose of this invention is to provide a high-adhesion epoxy resin composition and its application in semiconductor chip packaging. By introducing a photoresponsive modified anhydride grafted with photosensitive groups and a core-shell structured nanocomposite filler with a surface coated with a near-infrared light-absorbing dye layer, and in conjunction with a microencapsulated photothermal dual-response promoter, the composition, after being packaged into a photonic semiconductor chip, can utilize the specific wavelength of light generated by the chip operation to trigger the rearrangement and microstructure optimization of the curing network. At the same time, through the synergistic effect of photothermal conversion of the nanocomposite filler, a comprehensive improvement in linear expansion coefficient, thermal conductivity, aging resistance, and adhesive strength is achieved while maintaining high light transmittance.

[0008] To achieve the above objectives, one objective of this invention is to provide a high-adhesion epoxy resin composition comprising the following raw materials in the indicated mass percentages: The composition consists of 30-50% photoresponsive modified acid anhydride, 5-15% nanocomposite filler, 0.5-3% photothermal dual-response promoter, 0.5-2% interface-modified coupling agent, 0.1-1% high-efficiency mold release agent, and the balance being heterocyclic epoxy resin. The heterocyclic epoxy resin is at least one of the epoxy resins containing a triazine ring, an isocyanuric acid ring, or a hydantoin ring structure. The photoresponsive modified acid anhydride is a partial esterification product formed by methyl hexahydrophthalic anhydride or methyl tetrahydrophthalic anhydride and a polyol, and the partial esterification product is grafted with a photosensitive group. The nanocomposite filler is at least one of nano-tin indium oxide, nano-tin antimony oxide, or doped nano-tungsten bronze with a primary particle size of 10-80 nm after surface organic modification, and the surface of the nanocomposite filler is further coated or bonded with a layer of near-infrared light absorbing dye to form a core-shell structured photothermal functional body. The photothermal dual-response promoter is at least one of quaternary ammonium salt, quaternary phosphonium salt, tertiary amine or imidazole compound, and the promoter is adsorbed and encapsulated by a porous inorganic carrier to form a microencapsulated latent promoter.

[0009] As a further improvement to this technical solution, the photosensitive group grafted into the photoresponsive modified anhydride is a photosensitive monomer containing a chalcone structure or a coumarin structure.

[0010] As a further improvement to this technical solution, in the nanocomposite filler, the near-infrared light-absorbing dye layer is a cyanine dye or a metal complex dye.

[0011] As a further improvement to this technical solution, in the photothermal dual-response promoter, the porous inorganic carrier is mesoporous silica or molecular sieve.

[0012] As a further improvement to this technical solution, the epoxy equivalent of the heterocyclic epoxy resin is 180-250 g / eq.

[0013] As a further improvement to this technical solution, the interface modification coupling agent is a silane coupling agent or a titanate coupling agent.

[0014] As a further improvement to this technical solution, the high-efficiency release agent is at least one of synthetic wax, fatty acid ester or silicone oil compound.

[0015] The second objective of this invention is to provide the application of the above-mentioned high-adhesion epoxy resin composition in semiconductor chip packaging.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This high-adhesion epoxy resin composition and its application in semiconductor chip packaging, by introducing photoresponsive modified acid anhydride grafted with photosensitive groups, core-shell structured nanocomposite filler with a surface coated with near-infrared light-absorbing dye layer, and microencapsulated latent photothermal dual-response promoter into a heterocyclic epoxy resin matrix, constructs a dynamic self-optimizing encapsulation material system with synergistic effects of photo-thermal-chemical multiple responses. Meanwhile, this specific composition can synergistically perform multiple functions during the service of optoelectronic semiconductor chips, including photoinduced network rearrangement, interfacial photothermal conversion promoting thermal conductivity, and secondary repair by microcapsule promoters. This allows the composition to achieve a comprehensive benefit of significantly reducing the linear expansion coefficient, nonlinearly improving thermal conductivity, continuously enhancing adhesive strength, and greatly extending aging resistance life, while realizing the dual optical functions of high light transmittance and efficient infrared cutoff. It fundamentally overcomes the industry problem that existing epoxy encapsulation materials cannot simultaneously achieve multiple key indicators such as optical performance, thermomechanical reliability, and long-term service stability. It successfully prepares a high-performance, high-reliability epoxy resin composition suitable for the packaging needs of high-sensitivity optical sensors, high-power integrated chips, and optoelectronic devices under harsh conditions. Attached Figure Description

[0017] Figure 1 This is a schematic diagram showing the thermal conductivity of each group in the experimental examples of this invention; Figure 2 This is a schematic diagram showing the shear strength retention rate of each group after high temperature and high humidity in the test examples of this invention. Detailed Implementation

[0018] The technical solutions in 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.

[0019] In the field of semiconductor chip packaging, epoxy resin is mainly used in the form of epoxy molding compounds. Through molding processes, a protective layer is formed, which not only secures the connection between the chip and the substrate but also allows for precise control of the material's curing temperature, shrinkage rate, and dielectric properties by adjusting the ratio of fillers and additives. This meets the packaging requirements of chips in high-temperature, high-pressure, or corrosive environments. However, with the rapid development of optoelectronic integration technology and high-power chips, the packaging environment poses more stringent challenges to the optical properties, thermomechanical reliability, and long-term stability of materials. Existing epoxy resin material systems are gradually revealing inherent contradictions in addressing these complex requirements.

[0020] In the fields of optical sensors and optoelectronic semiconductor packaging, functional fillers are often introduced into the resin matrix to achieve precise control of specific wavelengths of light. For example, to achieve infrared cutoff, fillers such as metal oxides (e.g., WO3) are added. However, these inorganic fillers have significant differences in refractive index and surface polarity compared to the epoxy resin matrix, resulting in poor interfacial compatibility and difficulty in dispersion. This not only affects the thoroughness of infrared cutoff but also causes significant transmittance loss due to interfacial light scattering, impacting the accuracy of signal transmission.

[0021] Furthermore, to maintain the transparency of the packaging material and ensure luminous efficacy, traditional solutions typically avoid adding inorganic fillers. However, this results in an excessively high coefficient of linear expansion for the material. During stringent processes such as lead-free reflow soldering (above 260°C), the high-temperature environment, far exceeding the glass transition temperature, causes the package to expand rapidly, generating enormous thermal stress. This can easily lead to delamination at the interface between the package and the chip (such as a large-scale integrated circuit) or lead frame, and even break the gold wires, causing device failure. In addition, insufficient filler also results in poor thermal conductivity, making it difficult to dissipate the heat generated during chip operation in a timely manner, exacerbating luminous decay and reliability issues caused by heat accumulation.

[0022] Even though some patents attempt to address light interference by introducing colorants, these colorants are often small molecules that are prone to migration, degradation, or discoloration under high temperature, high humidity, or long-term light irradiation, causing drift in the device's optical parameters and compromising its aging resistance and long-term reliability. Existing commercially available products generally exhibit trade-offs in key performance indicators such as light aging resistance, infrared cutoff efficiency, molding process efficiency, and packaging reliability, making it difficult to meet the combined requirements of next-generation high-sensitivity optical sensors and highly integrated chips for packaging materials that possess both excellent optical performance and high structural reliability.

[0023] Therefore, the object of the present invention is to provide a high-adhesion epoxy resin composition comprising the following raw materials in the following mass percentages: The composition consists of 30-50% photoresponsive modified acid anhydride, 5-15% surface-functionalized nanocomposite filler, 0.5-3% latent photothermal dual-response promoter, 0.5-2% interface-modified coupling agent, 0.1-1% high-efficiency mold release agent, and the balance being heterocyclic epoxy resin.

[0024] Among them, heterocyclic epoxy resin is at least one of epoxy resins containing triazine ring, isocyanuric acid ring or hydantoin ring structure, and its epoxy equivalent is 180-250 g / eq. The photoresponsive modified acid anhydride is a partial esterification product formed by methyl hexahydrophthalic anhydride or methyl tetrahydrophthalic anhydride and a polyol, and the partial esterification product is grafted with a photosensitive group. In this invention, a photosensitive monomer containing a chalcone structure or a coumarin structure is preferred. The surface-functionalized nanocomposite filler is at least one of nano-indium tin oxide (ITO), nano-antimony tin oxide (ATO), or doped nano-tungsten bronze with a primary particle size of 10-80 nm after surface organic modification. Furthermore, the surface of the nanocomposite filler is coated or bonded with a layer of near-infrared light-absorbing dye to form a core-shell structured photothermal functional body. In this invention, cyanine dyes or metal complex dyes are preferred. The latent photothermal dual-response promoter is at least one of quaternary ammonium salt, quaternary phosphonium salt, tertiary amine or imidazole compound, and the promoter is adsorbed and encapsulated by a porous inorganic carrier (preferably mesoporous silica or molecular sieve in this invention) to form a microencapsulated latent promoter. The interface modification coupling agent is a silane coupling agent or a titanate coupling agent, used for the pretreatment or direct addition of nanofunctional fillers to improve the interfacial compatibility between inorganic fillers and resin matrix; the high-efficiency release agent is at least one of synthetic wax, fatty acid ester or silicone oil compound, used to improve the release performance of the composition during the molding process.

[0025] The above-mentioned heterocyclic epoxy resin and photoresponsive modified acid anhydride were added into a reaction vessel according to the specified ratio, and stirred and mixed at 40-60℃ for 30-60 min to obtain a resin-curing agent premix. The interface-modifying coupling agent was diluted with anhydrous ethanol to a concentration of 5-10%, sprayed onto the surface of the surface-functionalized nanocomposite filler, and dried at 80-100℃ for 1-2 hours to obtain the coupling agent-modified nanofiller. Add the coupling agent-modified nanofiller, latent photothermal dual-response promoter, and high-efficiency release agent to the resin-curing agent premix in sequence, and disperse at high speed at 2000-3000 rpm for 15-30 min to ensure that all components are fully mixed and uniform. The mixture is transferred to a three-roll mill for grinding and dispersion. The grinding fineness is controlled to ensure that the filler particle size is ≤20μm, so that the nanofiller is uniformly dispersed in the resin matrix. After grinding, the material is placed in a vacuum degassing machine and degassed for 20-40 minutes under a vacuum of -0.08 to -0.1MPa to remove the air bubbles introduced during the stirring process, thus obtaining a high-adhesion epoxy resin composition. To produce a solid encapsulation material, the degassed composition is poured into a mold and placed in an oven for curing using a stepped heating program of 80℃ / 2h + 120℃ / 2h + 150℃ / 4h. After cooling, the material is demolded to obtain the final product.

[0026] In this invention, the photoresponsive dynamic curing system and the photothermal synergy of nanofillers enable the encapsulation material to possess self-optimizing capabilities during use. Specifically, this invention uses modified acid anhydrides grafted with photosensitive groups (such as chalcone or coumarin structures) as curing agents, combined with core-shell structured nanocomposite fillers (such as ITO / ATO@cyanine dyes) with a surface-coated near-infrared light-absorbing dye layer, and microencapsulated latent photothermal dual-response promoters. After encapsulation of a photonic semiconductor chip, this composition can trigger multiple responses using specific wavelengths of light (300-1100nm) generated by the chip's operation: on the one hand, the photosensitive acid anhydride induces the rearrangement of the cured network under light irradiation, releasing internal stress and filling microscopic defects, thereby significantly reducing the linear expansion coefficient and improving adhesive strength; on the other hand, the light-absorbing layer on the surface of the nanofiller converts light energy into heat energy, forming a local micro-heating zone at the micro-interface, reducing the interfacial thermal resistance between the filler and the matrix, and achieving a non-linear improvement in thermal conductivity; simultaneously, the microencapsulated promoter can respond secondaryly during long-term service, repairing the aging interface and significantly extending the aging resistance. Through the synergistic effect of the above-mentioned photo-thermal-chemical multiple responses, the present invention successfully achieves comprehensive optimization of linear expansion coefficient, thermal conductivity, aging resistance and bonding strength while maintaining high light transmittance, overcoming the long-standing technical bias in the prior art that it is difficult to balance optical performance and thermomechanical reliability.

[0027] The high-adhesion epoxy resin composition provided by the present invention will be further illustrated by the following specific embodiments. Example 1

[0028] This embodiment provides a high-adhesion epoxy resin composition comprising the following raw materials in the indicated mass percentages: The composition consists of 30% photoresponsive modified acid anhydride, 15% surface-functionalized nanocomposite filler, 0.5% latent photothermal dual-response promoter, 2% interface-modified coupling agent, 0.1% high-efficiency mold release agent, and the balance being heterocyclic epoxy resin.

[0029] Among them, the heterocyclic epoxy resin is an epoxy resin containing a triazine ring structure, and its epoxy equivalent is 250 g / eq; The photoresponsive modified acid anhydride is a partial esterification product formed by methyl hexahydrophthalic anhydride and polyol, and the partial esterification product is grafted with a photosensitive group, which is a photosensitive monomer containing a coumarin structure. The surface-functionalized nanocomposite filler consists of nano-tin indium oxide and doped nano-tungsten bronze with a primary particle size of 10 nm, which have undergone surface organic modification. Furthermore, a near-infrared light-absorbing dye layer is provided on the surface of the nanocomposite filler, and the near-infrared light-absorbing dye layer is a cyanine dye. The latent photothermal dual-response promoter is a quaternary ammonium salt and a quaternary phosphonium salt, and the promoter is adsorbed and encapsulated by a porous inorganic carrier (mesoporous silica) to form a microencapsulated latent promoter; The interface-modifying coupling agent is a silane coupling agent; the high-efficiency release agent is a synthetic wax or fatty acid ester.

[0030] The above-mentioned heterocyclic epoxy resin and photoresponsive modified acid anhydride were added into a reaction vessel according to the specified ratio and stirred and mixed at 60°C for 30 minutes to obtain a resin-curing agent premix. The interface-modifying coupling agent was diluted with anhydrous ethanol to a concentration of 10%, sprayed onto the surface of the surface-functionalized nanocomposite filler, and dried at 80°C for 2 hours to obtain the coupling agent-modified nanofiller. The coupling agent-modified nanofiller, latent photothermal dual-response promoter, and high-efficiency release agent were sequentially added to the resin-curing agent premix and dispersed at high speed at 2000 rpm for 30 minutes to ensure that all components were fully mixed and uniform. The mixture was transferred to a three-roll mill for grinding and dispersion. The grinding fineness was controlled to ensure that the filler particle size was ≤20μm, so that the nanofiller was uniformly dispersed in the resin matrix. After grinding, the material was placed in a vacuum degassing machine and degassed for 40 minutes under a vacuum of -0.08MPa to remove the air bubbles introduced during the stirring process, thus obtaining a high-adhesion epoxy resin composition. Example 2

[0031] This embodiment provides a high-adhesion epoxy resin composition comprising the following raw materials in the indicated mass percentages: The composition consists of 40% photoresponsive modified acid anhydride, 10% surface-functionalized nanocomposite filler, 2.5% latent photothermal dual-response promoter, 1% interface-modified coupling agent, 0.5% high-efficiency mold release agent, and the balance being heterocyclic epoxy resin.

[0032] Among them, the heterocyclic epoxy resin is an epoxy resin containing triazine ring and isocyanuric acid ring structure, and its epoxy equivalent is 220 g / eq; The photoresponsive modified acid anhydride is a partial esterification product formed by methyltetrahydrophthalic anhydride and polyol, and the partial esterification product is grafted with a photosensitive group, and the photosensitive group is a photosensitive monomer containing a chalcone structure. The surface-functionalized nanocomposite filler is a nano-tin antimony oxide with a primary particle size of 50 nm that has undergone surface organic modification. Furthermore, a near-infrared light absorbing dye layer is provided on the surface of the nanocomposite filler, and the near-infrared light absorbing dye layer is a cyanine dye. The latent photothermal dual-response promoter is a tertiary amine compound, and the promoter is adsorbed and encapsulated by a porous inorganic carrier (molecular sieve) to form a microencapsulated latent promoter. The interface modification coupling agent is a silane coupling agent; the high-efficiency release agent is a synthetic wax, fatty acid ester, and silicone oil compound.

[0033] The above-mentioned heterocyclic epoxy resin and photoresponsive modified acid anhydride were added into a reaction vessel according to the specified ratio and stirred and mixed at 50°C for 45 minutes to obtain a resin-curing agent premix. The interface-modifying coupling agent was diluted with anhydrous ethanol to a concentration of 7%, sprayed onto the surface of the surface-functionalized nanocomposite filler, and dried at 90°C for 2 hours to obtain the coupling agent-modified nanofiller. The coupling agent-modified nanofiller, latent photothermal dual-response promoter, and high-efficiency release agent were sequentially added to the resin-curing agent premix and dispersed at high speed at 2500 rpm for 20 min to ensure that all components were fully mixed and homogeneous. The mixture was transferred to a three-roll mill for grinding and dispersion. The grinding fineness was controlled to ensure that the filler particle size was ≤20μm, so that the nanofiller was uniformly dispersed in the resin matrix. After grinding, the material was placed in a vacuum degassing machine and degassed for 30 minutes under a vacuum of -0.09MPa to remove the air bubbles introduced during the stirring process, thus obtaining a high-adhesion epoxy resin composition. Example 3

[0034] This embodiment provides a high-adhesion epoxy resin composition comprising the following raw materials in the indicated mass percentages: The composition consists of 50% photoresponsive modified acid anhydride, 5% surface-functionalized nanocomposite filler, 3% latent photothermal dual-response promoter, 0.5% interface-modified coupling agent, 1% high-efficiency mold release agent, and the balance being heterocyclic epoxy resin.

[0035] Among them, heterocyclic epoxy resin is an epoxy resin containing triazine ring, isocyanuric acid ring or hydantoin ring structure, and its epoxy equivalent is 180 g / eq. The photoresponsive modified acid anhydride is a partial esterification product formed by methyltetrahydrophthalic anhydride and polyol, and the partial esterification product is grafted with a photosensitive group, and the photosensitive group is a photosensitive monomer with a coumarin structure. The surface-functionalized nanocomposite filler consists of nano-tin indium oxide, nano-tin antimony oxide, and doped nano-tungsten bronze with a primary particle size of 80 nm after surface organic modification. Furthermore, a near-infrared light absorbing dye layer is provided on the surface of the nanocomposite filler, and the near-infrared light absorbing dye layer is a metal complex dye. The latent photothermal dual-response promoters are quaternary ammonium salts, quaternary phosphonium salts, tertiary amines and imidazole compounds, and the promoters are adsorbed and encapsulated by porous inorganic carriers (mesoporous silica) to form microencapsulated latent promoters; The interface modification coupling agent is a titanate coupling agent; the high-efficiency release agent is a synthetic wax.

[0036] The above-mentioned heterocyclic epoxy resin and photoresponsive modified acid anhydride were added into a reaction vessel according to the specified ratio and stirred and mixed at 40°C for 60 min to obtain a resin-curing agent premix. The interface-modifying coupling agent was diluted with anhydrous ethanol to a concentration of 5%, sprayed onto the surface of the surface-functionalized nanocomposite filler, and dried at 100°C for 1 hour to obtain the coupling agent-modified nanofiller. The coupling agent-modified nanofiller, latent photothermal dual-response promoter, and high-efficiency release agent were sequentially added to the resin-curing agent premix and dispersed at high speed at 3000 rpm for 15 min to ensure that all components were fully mixed and homogeneous. The mixture was transferred to a three-roll mill for grinding and dispersion. The grinding fineness was controlled to ensure that the filler particle size was ≤20μm, so that the nanofiller was uniformly dispersed in the resin matrix. After grinding, the material was placed in a vacuum degassing machine and degassed for 20 minutes under a vacuum of -0.1MPa to remove the air bubbles introduced during the stirring process, thus obtaining a high-adhesion epoxy resin composition.

[0037] The high-adhesion epoxy resin composition was prepared according to the contents provided in Examples 1-3. Then, the composition was tested for optical properties, thermomechanical properties, adhesive properties and aging resistance to evaluate its core performance in optical semiconductor chip packaging applications.

[0038] First, Comparative Example 1 was set up: conventional methylhexahydrophthalic anhydride (without photosensitive groups) was used to replace the photoresponsive modified anhydride, and the nanofiller was not coated with a near-infrared absorption layer. The remaining components and proportions were the same as in Example 2. Comparative Example 2: Commercially available high thermal conductivity epoxy encapsulation material with high filler content was used.

[0039] Then, the following test was performed: Optical performance testing Transmittance test: The composition was cast into a 1mm thick sheet and cured according to the following curing procedure: 80℃ / 2h + 120℃ / 2h + 150℃ / 4h. Its transmittance in the 400-1100nm wavelength range was then measured using a UV-Vis-NIR spectrophotometer. The average transmittance in the visible light region (400-700nm) was required to be no less than 85% to ensure efficient optical signal transmission.

[0040] Infrared cutoff efficiency test: Using the same sample as described above, the average transmittance in the near-infrared region (800-1100nm) was tested. The results are shown in Table 1.

[0041] Table 1 Optical properties of the high-adhesion epoxy resin compositions of Examples 1-3

[0042] Thermomechanical property testing Linear expansion coefficient test: The linear expansion coefficient (α1) of the cured sample below the glass transition temperature was measured using a thermomechanical analyzer, according to ASTM E831 standard, under a nitrogen atmosphere, with a heating rate of 5℃ / min from 25℃ to 200℃.

[0043] Glass transition temperature test: The glass transition temperature of the cured sample was determined using a differential scanning calorimeter at a heating rate of 10℃ / min, in accordance with ASTM E1356 standard.

[0044] Thermal conductivity testing: The thermal conductivity of the cured samples was measured using a laser flash thermal conductivity meter at 25°C according to ASTM E1461 standard. The results are shown in Table 2.

[0045] Table 2. Thermomechanical properties of the high-adhesion epoxy resin compositions of Examples 1-3

[0046] Adhesion performance test Shear strength test: The composition was coated between the silver-plated copper frame and the silicon chip. After curing, the shear strength was measured using a universal testing machine at a tensile speed of 5 mm / min according to ASTM D1002 standard.

[0047] Tensile strength test: The composition was cast into dumbbell-shaped specimens, and after curing, the tensile strength was determined using a universal testing machine according to ASTM D638 standard. The results are shown in Table 3.

[0048] Table 3. Adhesive properties of the high-adhesion epoxy resin compositions in Examples 1-3

[0049] Photoresponse performance test Performance optimization test after light irradiation: The cured sample was irradiated for 30 minutes under ultraviolet light at a wavelength of 365 nm or near-infrared light at a wavelength of 808 nm, with an irradiation intensity of 100 mW / cm². The linear expansion coefficient, thermal conductivity, and shear strength were measured before and after irradiation, and the performance change rate was calculated. The results are shown in Table 4.

[0050] Table 4. Photoresponse properties of the high-adhesion epoxy resin compositions in Examples 1-3

[0051] Aging resistance test High temperature and high humidity aging test: The cured sample was placed in a constant temperature and humidity chamber at 85℃ / 85%RH for 1000 hours. Every 250 hours, the sample was taken out to test the shear strength and light transmittance, and the performance retention rate was calculated.

[0052] Thermal cycling aging test: The cured sample was placed in a thermal cycling chamber ranging from -55℃ to 125℃, with each cycle lasting 30 minutes and a dwell time of 15 minutes, for a total of 1000 cycles. After every 250 cycles, the sample was removed and its shear strength was tested to observe for microcracks or delamination.

[0053] Photoaging test: The cured samples were placed in a UV aging chamber using a 340nm UV lamp with an irradiance of 0.89 W / m². The cycle conditions were 8 hours of light exposure / 4 hours of condensation, for a total of 500 hours. The results are shown in Table 5.

[0054] Table 5. Aging resistance of the high-adhesion epoxy resin compositions in Examples 1-3

[0055] According to Table 1-5, we can see that: First, the high-adhesion epoxy resin compositions prepared in Examples 1-3 of this invention meet or exceed the set test requirements in all core performance indicators. In terms of optical performance, the transmittance in the visible light region reaches 87.6-89.2%, and the transmittance in the infrared region is controlled at 2.8-4.1%, successfully achieving the dual optical functions of high transmittance and infrared cutoff, thus resolving the technical contradiction of balancing optical performance with filler addition.

[0056] Secondly, in terms of thermomechanical properties, the linear expansion coefficient of the embodiments is 30-34 ppm / ℃, the glass transition temperature is 158-168℃, and the thermal conductivity is 0.58-0.68 W / (m·K), all of which are significantly better than conventional encapsulation materials without added functional fillers (Comparative Example 1). At the same time, compared with commercially available high thermal conductivity materials (Comparative Example 2), it exhibits better optical properties and adhesive strength while maintaining acceptable thermal conductivity.

[0057] Third, the photoresponse performance test results show that after near-infrared light irradiation, the linear expansion coefficient of the embodiment decreased by 7.2-12.3%, the thermal conductivity increased by 15.2-25.4%, and the shear strength increased by 10.3-16.8%. This self-optimizing characteristic was almost not observed in the comparative examples, proving that the present invention successfully achieved dynamic performance optimization of the encapsulation material during use through the synergistic effect of photoresponsive modified acid anhydride and core-shell structured nanocomposite filler, producing unexpected technical effects.

[0058] Fourth, in terms of aging resistance, after high temperature and humidity, thermal cycling and ultraviolet aging treatment, the performance retention rate of the embodiments reached more than 84%, which is significantly better than Comparative Example 1 (58-72%), and slightly better than or equivalent to Comparative Example 2 (82-91%), proving its reliability and stability in long-term service environment.

[0059] In summary, the high-adhesion epoxy resin composition provided by this invention constructs a photo-thermal-chemical multi-response synergistic system by introducing photoresponsive modified anhydride, core-shell structured nanocomposite filler, and microencapsulated latent promoter into the formulation. It successfully achieves effective cutoff of infrared rays while maintaining high light transmittance, and exhibits excellent comprehensive performance in terms of linear expansion coefficient, thermal conductivity, adhesive strength, and aging resistance. It is particularly suitable for the field of optical semiconductor chip packaging where optical performance and structural reliability requirements are stringent.

[0060] Test case To verify that the synergistic system consisting of photoresponsive modified acid anhydride, core-shell structured surface-functionalized nanocomposite filler, and microencapsulated latent photothermal dual-response promoter is the key to achieving dynamic self-optimization performance of the encapsulation material in this invention, this experimental example is based on the formulation and process of Example 2. By systematically changing the core technical features, the following eleven sets of comparative experiments were designed to verify the necessity of each component and the rationality of the ratio range.

[0061] I. Experimental Design Control group F1 (without photosensitive anhydride) Solution: Use conventional methylhexahydrophthalic anhydride (without photosensitive groups) to replace the photoresponsive modified anhydride. The remaining components and proportions are exactly the same as in Example 2.

[0062] Objective: To verify the key role of photosensitive groups in photo-induced curing network rearrangement, reduction of linear expansion coefficient, and improvement of adhesive strength.

[0063] Control group F2 (coreless shell packing group) Solution: Ordinary nano-antimony tin oxide (ATO, primary particle size 50nm, surface organic modification) without near-infrared dye coating is used to replace the surface functionalized nanocomposite filler. The remaining components and proportions are the same as in Example 2.

[0064] Objective: To verify the necessity of the photothermal conversion function of the core-shell structure for improving thermal conductivity and synergistic photoresponse performance.

[0065] Control group F3 (without microcapsule promoter) Solution: Use an equal amount of uncoated tertiary amine accelerator (the same type as the accelerator in Example 2, but without mesoporous silica adsorption coating) to replace the latent photothermal dual-response accelerator, and the remaining components and proportions are the same as in Example 2.

[0066] Objective: To verify the role of microencapsulation in ensuring the latency of accelerators and their secondary repair function during long-term service.

[0067] Control group F4 (low acid anhydride content group) Solution: The mass ratio of photoresponsive modified acid anhydride is adjusted to 20% (lower than the lower limit of 30% in this invention), and the remaining components and proportions are the same as in Example 2.

[0068] Objective: To verify the effect of insufficient crosslinking density on performance when the anhydride content is lower than the range of this invention.

[0069] Control group F5 (high acid anhydride content group) Solution: The mass ratio of photoresponsive modified anhydride is adjusted to 60% (higher than the upper limit of 50% in this invention), and the remaining components and proportions are the same as in Example 2.

[0070] Objective: To verify the negative impact of excessive acid anhydride content on the uniformity and light transmittance of the cured network.

[0071] Control group F6 (low nanofiller content group) Solution: The mass percentage of surface-functionalized nanocomposite filler is adjusted to 3% (lower than the lower limit of 5% in this invention), and the remaining components and proportions are the same as in Example 2.

[0072] Objective: To verify the weakening effect of insufficient filler content on infrared cutoff efficiency, thermal conductivity and photothermal conversion synergy.

[0073] Control group F7 (high nanofiller content group) Solution: The mass ratio of surface functionalized nanocomposite filler is adjusted to 20% (higher than the upper limit of 15% in this invention), and the remaining components and ratios are the same as in Example 2.

[0074] Objective: To verify the damage of excessive filler to light transmittance and dispersion uniformity.

[0075] Control group F8 (low accelerator content group) Solution: The mass percentage of the latent photothermal dual-response promoter is adjusted to 0.2% (lower than the lower limit of 0.5% of this invention), and the remaining components and proportions are the same as in Example 2.

[0076] Objective: To verify that insufficient accelerator leads to incomplete curing and performance degradation.

[0077] Control group F9 (high accelerator content group) Solution: The mass percentage of the latent photothermal dual-response promoter is adjusted to 4% (higher than the upper limit of 3% in this invention), and the remaining components and proportions are the same as in Example 2.

[0078] Objective: To verify the effect of excessive accelerator on storage stability and controllability of curing rate.

[0079] Control group F10 (single-function combination group) Solution: Common acid anhydride, common nanofiller (core-shell-free) and common accelerator (microcapsule-free) are used simultaneously, and the remaining components and proportions are the same as in Example 2.

[0080] Objective: To simulate the simple mixing of conventional components in existing technologies as a benchmark.

[0081] Control group F11 (Example 2 of the present invention) Solution: The complete optimized solution of this invention is as follows: 40% photoresponsive modified acid anhydride, 10% surface functionalized nanocomposite filler, 2.5% latent photothermal dual-response promoter, 1% interface-modified coupling agent, 0.5% high-efficiency mold release agent, and the balance is heterocyclic epoxy resin.

[0082] Objective: To serve as a reference group for optimizing the formulation.

[0083] II. Testing Methods and Indicators Following the same testing method as described in the aforementioned specific implementation, the following key performance tests were performed on the above eleven groups of samples: Optical performance: transmittance in the visible light region (550nm), transmittance in the infrared region (900nm); Thermomechanical properties: coefficient of linear expansion (α1), thermal conductivity; Adhesive properties: shear strength; Optical response performance: After irradiation with 808nm near-infrared light for 30 minutes, the rate of change of linear expansion coefficient, the rate of change of thermal conductivity, and the rate of change of shear strength; Aging resistance: Shear strength retention rate after high temperature and high humidity (85℃ / 85%RH, 1000h).

[0084] III. Test Results The test results are shown in Table 6 and Figure 1-2As shown.

[0085] Table 6. Experimental results verifying the synergistic effect and the necessity of the ratio of the core components of this invention.

[0086] According to Table 6 and Figure 1-2 It can be known that, 1. The necessity of photoresponsive modified acid anhydrides (F1 vs F11) While group F1 (without photosensitive anhydride) maintained good light transmittance and infrared cutoff (contributed by filler), its linear expansion coefficient was as high as 46 ppm / ℃, far exceeding that of group F11 (30 ppm / ℃); moreover, its performance showed almost no improvement after light exposure (α1 change rate was only -1.2%). This indicates that the photosensitive group is the core element in triggering the curing network rearrangement, releasing internal stress, and achieving a low expansion coefficient. Without photosensitive anhydride, the material is merely statically reinforced with filler and cannot be dynamically optimized during service.

[0087] 2. The necessity of core-shell structured nanocomposite fillers (F2 vs F11) The thermal conductivity of group F2 (core-shell-less filler) is only 0.42 W / (m·K), significantly lower than that of group F11 (0.68 W / (m·K); after illumination, the thermal conductivity increases by only 5.2%, while that of group F11 increases by 25.4%. This indicates that the photothermal conversion layer of the core-shell structure can efficiently convert light energy into heat energy, reduce interfacial thermal resistance, and achieve a nonlinear increase in thermal conductivity. Without this structure, the filler only plays a static thermal conduction role and cannot respond to illumination.

[0088] 3. The necessity of microencapsulation accelerators (F3 vs F11) Although the initial performance of group F3 (without microencapsulated accelerator) was similar to that of group F11, its shear strength retention rate after high temperature and humidity was only 71%, far lower than the 92% of group F11, and the performance improvement after light exposure was also slightly lower. This indicates that microencapsulation gives the accelerator latency, avoiding premature consumption during storage and initial curing, and allowing it to respond and repair the aging interface during long-term service, significantly improving aging resistance.

[0089] 4. Criticality of component content (F4-F9 vs F11) Anhydride content: F4 (20%) has a high α1 and low shear strength due to insufficient crosslinking; F5 (60%) has improved thermal properties, but its light transmittance is significantly reduced (82.1%), and high anhydride content may cause increased brittleness (although the performance improvement after light exposure is large, the initial light transmittance is already unacceptable). The present invention balances optical and mechanical properties within the range of 30-50%.

[0090] Nanofiller content: F6 (3%) has infrared cutoff failure (transmittance 15.8%) and low thermal conductivity; F7 (20%) has excellent infrared cutoff and high thermal conductivity, but its transmittance is only 75.3%, which cannot meet the high transmittance requirements. The present invention achieves a balance between optical and thermal performance by using a nanofiller content of 5-15%.

[0091] Accelerator content: F8 (0.2%) showed incomplete curing, with deterioration in α1 and shear strength; F9 (4%) showed acceptable performance, but its high temperature and humidity retention rate was only 68%, indicating that excessive accelerator destroyed latency and accelerated aging. The range of 0.5-3% in this invention ensures sufficient curing and long-term stability.

[0092] 5. On the completeness of synergistic effects (F10 vs F11) The F10 group (single-function combination) is inferior to the F11 group in all aspects: α1 is as high as 48 ppm / ℃, thermal conductivity is only 0.45 W / (m·K), performance is almost unimproved after light exposure, and the aging resistance retention rate is only 60%. This indicates that simply mixing the components without endowing them with specific responsive structures (photosensitive groups, core-shell, microcapsules) cannot produce a synergistic effect; the functions are independent of each other and may even interfere with each other. In contrast, the triple-response system of this invention is tightly coupled in time (latency during curing, response during service) and space, achieving a breakthrough effect.

[0093] Therefore, the absence or deviation of any single feature in the technical solution of this invention will lead to a significant decrease in key performance.

[0094] In summary, the comparative experiments of the above systems fully demonstrate that the photoresponsive modified acid anhydride, core-shell structured nanocomposite filler, and microencapsulated latent promoter proposed in this invention constitute an interconnected and synergistic technical system. This design successfully transforms the encapsulation material from a static process material into a dynamic, self-optimizing smart material, solving the core problems of existing technologies, such as the difficulty in simultaneously achieving high light transmittance, low expansion, and high thermal conductivity, as well as insufficient long-term reliability.

[0095] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-adhesion epoxy resin composition, characterized in that, Raw materials include the following mass percentages: The composition consists of 30-50% photoresponsive modified acid anhydride, 5-15% nanocomposite filler, 0.5-3% photothermal dual-response promoter, 0.5-2% interface-modified coupling agent, 0.1-1% high-efficiency mold release agent, and the balance being heterocyclic epoxy resin. The heterocyclic epoxy resin is at least one of the epoxy resins containing a triazine ring, an isocyanuric acid ring, or a hydantoin ring structure; the photoresponsive modified acid anhydride is a partial esterification product formed by methyl hexahydrophthalic anhydride or methyl tetrahydrophthalic anhydride and a polyol, and the partial esterification product is grafted with a photosensitive group. The nanocomposite filler is at least one of nano-tin indium oxide, nano-tin antimony oxide, or doped nano-tungsten bronze with a primary particle size of 10-80 nm after surface organic modification, and the surface of the nanocomposite filler is further coated or bonded with a layer of near-infrared light absorbing dye to form a core-shell structured photothermal functional body. The photothermal dual-response promoter is at least one of quaternary ammonium salt, quaternary phosphonium salt, tertiary amine or imidazole compound, and the promoter is adsorbed and encapsulated by a porous inorganic carrier to form a microencapsulated latent promoter.

2. The high-adhesion epoxy resin composition according to claim 1, characterized in that: The photosensitive groups grafted into the photoresponsive modified acid anhydride are photosensitive monomers containing chalcone or coumarin structures.

3. The high-adhesion epoxy resin composition according to claim 1, characterized in that: In the nanocomposite filler, the near-infrared light-absorbing dye layer is a cyanine dye or a metal complex dye.

4. The high-adhesion epoxy resin composition according to claim 1, characterized in that: In the photothermal dual-response promoter, the porous inorganic carrier is mesoporous silica or molecular sieve.

5. The high-adhesion epoxy resin composition according to claim 1, characterized in that: The epoxy equivalent of the heterocyclic epoxy resin is 180-250 g / eq.

6. The high-adhesion epoxy resin composition according to claim 1, characterized in that: The interface-modifying coupling agent is a silane coupling agent or a titanate coupling agent.

7. The high-adhesion epoxy resin composition according to claim 1, characterized in that: The high-efficiency release agent is at least one of synthetic wax, fatty acid ester, or silicone oil compound.

8. The use of the high-adhesion epoxy resin composition according to any one of claims 1-7 in semiconductor chip packaging.

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