A plug hole resin composition and a method for preparing the same

Abstract

The application discloses a plug hole resin composition and a preparation method thereof. The plug hole resin composition comprises a resin component, a curing system, an inorganic filler, a toughening agent, a coupling agent, an auxiliary agent and a solvent. The resin component comprises a bisphenol A type epoxy resin, a cyanate ester, a naphthalene ring type epoxy resin and / or a biphenyl type epoxy resin; the curing system comprises a microencapsulated dicyandiamide derivative curing agent and an imidazole type accelerator; and the inorganic filler comprises spherical silica, aluminum hydroxide and / or boehmite which are surface treated by a silane coupling agent. The plug hole resin composition of the application can be rapidly and completely cured at 100-120 DEG C, and has excellent electrical properties, heat resistance, mechanical properties and long-term high reliability after curing.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a pore-filling resin composition and its preparation method. Background Technology

[0002] With the rapid development of cutting-edge technologies such as 5G, artificial intelligence, and cloud computing, electronic devices are increasingly demanding higher signal transmission rates and data processing capabilities, making "high frequency and high speed" one of the trends in printed circuit boards (PCBs). To achieve higher density circuit interconnections, PCBs currently widely adopt structures such as blind vias, buried vias, and through-holes. Among these, via plugging is a key process step, its role being to prevent electroplating or etching solution residues, ensure surface flatness, and provide mechanical support for subsequent lamination, directly affecting the electrical performance and reliability of the PCB.

[0003] Existing via-filling resin compositions generally require curing at temperatures above 150°C for 60-90 minutes. This stringent process is not only energy-intensive and inefficient, but also conflicts with the thermal sensitivity of current high-frequency, high-speed substrates (such as LCP, PI, and PPO), leading to thermal damage and dimensional instability. It also poses reliability risks to heat-sensitive components in system-in-package (SIIP). In terms of material properties, existing via-filling resin compositions suffer from high dielectric constants and loss factors, mismatched coefficients of thermal expansion with the substrate leading to interface failures, and large curing shrinkage affecting surface smoothness. These shortcomings in both process and performance limit the application of existing via-filling resin compositions in high-frequency, high-speed PCBs. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention provides a pore-filling resin composition and a method for preparing the same. The pore-filling resin composition can be rapidly cured at a relatively low temperature, is suitable for temperature-sensitive substrates or substrates containing temperature-sensitive elements, and the cured pore-filling resin exhibits excellent heat resistance, electrical properties, and mechanical properties.

[0005] A pore-sealing resin composition according to a first aspect embodiment of the present invention is characterized in that, by weight, it comprises the following components: The resin component includes 10-20 parts of bisphenol A type epoxy resin, 10-20 parts of cyanate ester, and 5-15 parts of naphthyl ring type epoxy resin and / or biphenyl type epoxy resin. The curing system comprises 10-20 parts of microencapsulated dicyandiamide derivative curing agent and 0.5-3 parts of imidazole accelerator; wherein the microencapsulated dicyandiamide derivative curing agent comprises a core material and a wall material, the core material being a dicyandiamide derivative, and the wall material being a thermoresponsive polymer with a thermal response temperature of 100-120℃; Inorganic filler, wherein the inorganic filler comprises 15-30 parts of spherical silica, 5-10 parts of aluminum hydroxide and / or boehmite after surface treatment with silane coupling agent; 3-8 parts toughening agent, 0.5-2 parts coupling agent, 0.5-2 parts other additives and 5-15 parts solvent.

[0006] According to some embodiments of the present invention, the cyanate ester includes at least one of bisphenol E cyanate ester and bisphenol A cyanate ester.

[0007] According to some embodiments of the present invention, the naphthalene ring type epoxy resin includes at least one of 2,7-dihydroxynaphthalene diglycidyl ether, 1,6-dihydroxynaphthalene diglycidyl ether, and naphthol type epoxy resin; the biphenyl type epoxy resin includes at least one of biphenyl diglycidyl ether compounds, biphenyl type phenolic epoxy resin, and biphenyl type aralkyl epoxy resin.

[0008] According to some embodiments of the present invention, the dicyandiamide derivative includes at least one of alkyl-substituted dicyandiamide, aromatic-substituted dicyandiamide, dicyandiamide condensed with urea, and dicyandiamide condensed with amine; the thermoresponsive polymer includes at least one of polyurethane, polyurea, and polyurethane-urea hybrid polymer.

[0009] According to some embodiments of the present invention, the microencapsulated dicyandiamide derivative curing agent is prepared by interfacial polymerization.

[0010] According to some embodiments of the present invention, the preparation of the microencapsulated dicyandiamide derivative curing agent includes the following steps: dissolving an emulsifier in deionized water to obtain an aqueous phase; dissolving or dispersing the dicyandiamide derivative constituting the core material in an organic solvent, adding monomer A constituting the wall material and stirring evenly to obtain an oil phase; mixing and emulsifying the oil phase and the aqueous phase to obtain an oil / water (O / W) emulsion; adding monomer B, which can react with monomer A to constitute the wall material, to the emulsion for interfacial polymerization to form the wall material; wherein, by weight, the ratio of the raw materials is: emulsifier: deionized water: dicyandiamide derivative: organic solvent: monomer A: monomer B = (1-2): (100-300): 10: (20-30): (5-8): (1-5).

[0011] According to some embodiments of the present invention, the imidazole accelerator includes at least one selected from 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-dihydroxymethylimidazole, and 2-heptadecylimidazole.

[0012] According to some embodiments of the present invention, the particle size D50 of the spherical silica is 1-5 μm, and the spherical silica is pretreated with a silane coupling agent.

[0013] According to some embodiments of the present invention, the toughening agent comprises at least one of core-shell structured rubber particles and carboxyl-terminated nitrile butadiene rubber (CTBN); the coupling agent comprises at least one of γ-glycidoxypropyltrimethoxysilane and γ-aminopropyltriethoxysilane; the solvent comprises at least one of propylene glycol methyl ether acetate (PMA) and diethylene glycol butyl ether acetate; and the additive comprises at least one of silicone leveling agents and silicone dispersants.

[0014] A method for preparing a pore-sealing resin composition according to a second aspect of the present invention is characterized by comprising the following steps: mixing a resin component and a toughening agent in a portion of a solvent, then adding an inorganic filler and a coupling agent for dispersion and grinding, and finally adding a curing system, other additives, and the remaining solvent; wherein the resin component comprises bisphenol A type epoxy resin, cyanate ester, naphthyl ring type epoxy resin, and / or biphenyl type epoxy resin, the inorganic filler comprises spherical silica, aluminum hydroxide surface-treated with a silane coupling agent, and / or boehmite, and the curing system comprises a microencapsulated dicyandiamide derivative curing agent and an imidazole accelerator.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The pore-filling resin composition of the present invention uses cyanate ester, naphthalene ring epoxy resin and / or biphenyl epoxy resin, combined with spherical silica. The cured pore-filling resin composition has a low dielectric constant (Dk) and a low dielectric loss factor (Df), meeting the high requirements of Dk≤3.3 and Df≤0.009 at a high frequency of 10GHz. The pore-sealing resin composition of the present invention achieves complete curing at 100-120°C within 30-50 minutes by using microencapsulated dicyandiamide derivative curing agent and compounding imidazole accelerator. Compared with traditional processes, it significantly reduces energy consumption and improves efficiency. The curing temperature of 100-120°C avoids thermal damage to heat-sensitive substrates and components in high-frequency and high-speed PCBs. The pore-filling resin composition of the present invention, through the synergistic effect of toughening agent and inorganic filler, combined with resin components, effectively reduces the curing shrinkage rate and thermal expansion coefficient of the pore-filling resin composition, ensuring long-term stability of the cured pore-filling resin composition under thermal cycling and mechanical stress, preventing failures such as pore opening cracks and delamination, and significantly improving product yield and lifespan. The pore-sealing resin composition of the present invention, through the compounding of additives and solvents, makes its rheological properties suitable for screen printing or dispensing, and has good process applicability; through the isolation effect of the microencapsulated dicyandiamide derivative curing agent microcapsules, the curing agent is physically isolated from the resin components during storage, preventing pre-reaction, improving room temperature storage stability, and extending room temperature storage period.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Detailed Implementation

[0017] To make the objectives and technical solutions of this invention clearer and easier to understand, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0018] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0019] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are all available from conventional commercial sources or can be obtained by existing known methods.

[0020] In a first aspect, embodiments of the present invention provide a pore-sealing resin composition, characterized in that, by weight, it comprises the following components: The resin components include 10-20 parts of bisphenol A type epoxy resin, 10-20 parts of cyanate ester, and 5-15 parts of naphthyl ring type epoxy resin and / or biphenyl type epoxy resin. The curing system includes 10-20 parts of microencapsulated dicyandiamide derivative curing agent and 0.5-3 parts of imidazole accelerator; wherein, the microencapsulated dicyandiamide derivative curing agent includes a core material and a wall material, the core material is a dicyandiamide derivative, and the wall material is a thermoresponsive polymer with a thermal response temperature of 100-120℃. Inorganic filler, comprising 15-30 parts of spherical silica, 5-10 parts of aluminum hydroxide and / or boehmite after surface treatment with silane coupling agent; 3-8 parts toughening agent, 0.5-2 parts coupling agent, 0.5-2 parts additives and 5-15 parts solvent.

[0021] Specifically, a main chain backbone constructed from low-polarity, low-viscosity bisphenol A type epoxy resin and cyanate ester is synergistically formed with naphthalene ring type epoxy resin and / or biphenyl type epoxy resin with low thermal expansion coefficient to form a low-polarity and rigid cross-linked network. This network possesses low dielectric constant and low dielectric loss, while providing excellent wettability and dispersion medium for spherical silica fillers, further reducing the polarizability and thermal expansion coefficient of the system. After curing, it exhibits low dielectric constant (Dk≤3.3), low dielectric loss (Df≤0.009), and low thermal expansion coefficient at 10GHz, meeting the requirements for high-frequency, high-speed signal transmission. Furthermore, by selecting microencapsulated dicyandiamide derivatives (thermal response temperature 100-120℃) that release at lower temperatures and combining them with a highly active imidazole accelerator, a high-frequency performance at 100-120℃ is achieved. The 30-50 minute curing process significantly reduces energy consumption, improves efficiency, and broadens the application range of the material compared to traditional processes. Furthermore, the microencapsulation of the dicyandiamide derivative curing agent isolates the curing agent from the resin during storage, preventing pre-reaction and improving room temperature storage stability, resulting in a storage period of ≥3 months. Optimized resin viscosity, thixotropy, and surface treatment of the inorganic filler give the pore-filling resin composition excellent filling properties, anti-settling properties, and printing / dispensing operability. The cured pore-filling resin composition has a flat, depression-free, and void-free surface, thus meeting the requirements of high-frequency, high-speed signal transmission while also possessing processing adaptability for large-scale industrial production.

[0022] In some embodiments, the cyanate ester includes at least one of bisphenol E cyanate and bisphenol A cyanate.

[0023] Specifically, bisphenol E cyanate and bisphenol A cyanate have low dielectric constants and dielectric losses, as well as good heat resistance. The addition of bisphenol E cyanate and / or bisphenol A cyanate is beneficial to improving the electrical and heat resistance properties of the pore-filling resin composition. Simultaneously, bisphenol E cyanate and bisphenol A cyanate can fully react with epoxy resin at a relatively low curing temperature of 100-120℃, and are compatible with microencapsulated dicyandiamide derivatives (thermal response temperature of 100-120℃), synergistically preventing thermal damage to heat-sensitive PCB substrates and components.

[0024] Furthermore, the low melt viscosity of bisphenol E cyanate and bisphenol A cyanate allows them to rapidly wet the surface of spherical silica fillers in the early stages of heating. This creates a synergistic anchoring effect with the specially treated coupling agent on the filler surface. On the one hand, this effectively prevents the formation of pores between the filler and the resin interface, reducing interfacial polarization loss. On the other hand, by forming a tight organic-inorganic composite structure, it further suppresses the coefficient of thermal expansion (CTE) of the cured pore-filling resin composition, thereby ensuring the dimensional stability of high-frequency, high-speed PCBs during repeated thermal cycling.

[0025] In some embodiments, the naphthyl ring epoxy resin includes at least one of 2,7-dihydroxynaphthalene diglycidyl ether, 1,6-dihydroxynaphthalene diglycidyl ether, and naphthol-type epoxy resin; the biphenyl-type epoxy resin includes at least one of biphenyl diglycidyl ether compounds, biphenyl-type phenolic epoxy resin, and biphenyl-type aralkyl epoxy resin.

[0026] Specifically, the fused-ring coplanar structure of naphthalene-type epoxy resins gives them good dimensional stability, a low coefficient of thermal expansion, and high thermal stability. The low polarization and hydrophobicity of the fused rings also result in low dielectric loss in high-humidity environments. The rigid backbone of naphthalene-type epoxy resins provides high cohesive force in the liquid state, offering better coating and support for inorganic fillers. This results in slower settling rates and better storage stability in highly filled formulations, along with higher compressive strength after curing and reduced cracking. Biphenyl-type epoxy resins, with their benzene rings linked by single bonds, possess a certain degree of intramolecular rotational freedom. This allows them to absorb impact energy through small changes in bond angles, achieving toughness buffering and giving the cured pore-filling resin a certain degree of resistance to mechanical impact. The linear structure of biphenyl-type epoxy resins also gives them low melt viscosity and excellent filling ability for deep pores (aspect ratios above 5:1). A mixture of naphthalene-cyclic epoxy resin and biphenyl-type epoxy resin exhibits both a low coefficient of thermal expansion and excellent resistance to mechanical impact. By adjusting the ratio of naphthalene-cyclic epoxy resin to biphenyl-type epoxy resin, compatibility between high filler content filling and deep hole filling can be achieved. The addition of naphthalene-cyclic epoxy resin and biphenyl-type epoxy resin improves the heat resistance, mechanical properties, electrical properties, and reliability of the hole-filling resin composition, making it suitable for use in high-frequency, high-speed PCBs under extreme environments such as high temperature and high humidity.

[0027] In some embodiments, the dicyandiamide derivative includes at least one of alkyl-substituted dicyandiamide, aromatic-substituted dicyandiamide, dicyandiamide condensed with urea, and dicyandiamide condensed with amine; the thermoresponsive polymer includes at least one of polyurethane, polyurea, and polyurethane-urea hybrid polymer.

[0028] Specifically, through alkylation, aromatization, or condensation with urea / amine, dicyandiamide derivatives exhibit better compatibility in resin compositions, forming homogeneous or finely dispersed systems, which improves curing uniformity. Furthermore, the curing temperature of dicyandiamide is typically above 180°C, resulting in high energy consumption and potential damage to heat-sensitive substrates. Dicyandiamide derivatives require lower activation energies, enabling curing at lower temperatures and effectively broadening the process window. The reactivity of dicyandiamide derivatives can be adjusted through substituent structure design, achieving a smoother curing curve, reducing the risk of explosive polymerization, and improving process stability. Simultaneously, the reduction of hydrophilic groups through end-capping or condensation enhances the moisture resistance and dielectric properties of the cured system. Thermoresponsive polymer wall materials, including polyurethane, polyurea, and polyurethane-urea hybrid polymers, can act as organic fillers uniformly dispersed in the crosslinked network after the pore-filling resin composition is cured. This improves the toughness, impact resistance, and dielectric properties of the cured pore-filling resin composition, thereby further enhancing its mechanical reliability and electrical properties.

[0029] Furthermore, the thermally responsive wall material undergoes melting, cracking, or drastic changes in permeability at the thermal response temperature (100-120℃). This allows the wall material to completely physically isolate the dicyandiamide derivative below the thermal response temperature, resulting in a stable system with a shelf life of ≥3 months, which can be extended to 6-12 months or even longer. Simultaneously, the microencapsulated dicyandiamide derivative curing agent is uniformly dispersed in the pore-filling resin composition, which is beneficial for the production, transportation, and construction of the pore-filling resin composition. Upon reaching the thermal response temperature, the wall material rapidly opens, releasing the dicyandiamide derivative and triggering rapid curing of the pore-filling resin composition. This makes the curing process of the pore-filling resin composition highly controllable. At the same time, the uniform dispersion of the microencapsulated dicyandiamide derivative curing agent effectively avoids local reaction differences caused by uneven distribution of the curing agent, resulting in more uniform curing of the pore-filling resin composition and reducing internal stress.

[0030] In some embodiments, the microencapsulated dicyandiamide derivative curing agent is prepared by interfacial polymerization.

[0031] Specifically, interfacial polymerization offers advantages such as high film-forming efficiency and high-performance microcapsule control. The polymerization reaction occurs only in the interfacial region, eliminating the need for intraphase reactions, resulting in short reaction times, high film-forming efficiency, and encapsulation rates exceeding 80%. By selecting different monomers, various polymeric wall materials, including polyurethane, polyurea, and polyurethane-urea hybrid polymers, can be prepared via interfacial polymerization. These polymeric wall materials exhibit high density, effectively blocking the influence of the external environment on the core material and improving stability. Furthermore, by adjusting monomer concentration, phase ratio, and emulsification conditions, the thickness, mechanical strength, porosity, and permeability of the wall material can be further controlled, enabling precise design of the thermally responsive release of the microcapsules.

[0032] In some embodiments, the microencapsulated dicyandiamide derivative curing agent is cured by interfacial polymerization, specifically including the following steps: Preparation of raw materials: The ratio of raw materials by weight is as follows: emulsifier: deionized water: dicyandiamide derivative: organic solvent: monomer A: monomer B = (1-2): (100-300): 10: (20-30): (5-8): (1-5); Preparation of the aqueous phase: The emulsifier is dissolved in deionized water to obtain the aqueous phase; Preparation of the oil phase: The dicyandiamide derivative constituting the core material is dissolved or dispersed in an organic solvent, monomer A constituting the wall material is added and stirred evenly to obtain the oil phase; Emulsification: The oil phase is slowly added to the aqueous phase under high-speed shear, and emulsification is performed to obtain an oil / water (O / W) emulsion. At this time, the dicyandiamide derivative is dispersed into tiny droplets. The high-speed shear rate is 5000-20000 s. -1 The oil phase is added slowly at a rate of 0.5–5 mL / min; Interfacial polymerization: Monomer B, which can react with monomer A to form a wall material, is added dropwise to the emulsion. Monomer B diffuses to the interface of tiny droplets formed by the dispersion of dicyandiamide derivatives in the oil phase and undergoes an interfacial polymerization reaction with monomer A to form a wall material. Post-processing: After filtration, washing and drying, microencapsulated dicyandiamide derivative curing agent is obtained.

[0033] Specifically, the emulsifier includes polyvinyl alcohol, preferably at least one of PVA-1788, PVA-217, and PVA-2088; the dicyandiamide derivative includes at least one of alkyl-substituted dicyandiamide, aromatic-substituted dicyandiamide, dicyandiamide condensed with urea, and dicyandiamide condensed with amine; the organic solvent includes xylene; monomer A and monomer B undergo interfacial polymerization to obtain the wall material, wherein the wall material is a thermoresponsive polymer and the thermal response temperature of the wall material is 100-120°C.

[0034] Furthermore, the wall material is a thermoresponsive polymer, which includes at least one of polyurethane, polyurea, and polyurethane-urea hybrid polymers; wherein, when the thermoresponsive polymer is polyurethane, monomer A is a polyisocyanate and monomer B is a polyol; when the thermoresponsive polymer is polyurea, monomer A is a polyisocyanate and monomer B is a polyamine; when the thermoresponsive polymer is a polyurethane-urea hybrid polymer, monomer A is a polyisocyanate and a polyol, and monomer B is a polyamine.

[0035] In some embodiments, the imidazole accelerator includes at least one of 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-dihydroxymethylimidazole, and 2-heptadecylimidazole.

[0036] Specifically, imidazole accelerators remain stable at room temperature, ensuring good storage stability of the pore-filling resin composition. When heated to a certain temperature (above 100°C), they efficiently trigger and accelerate the curing reaction of the pore-filling resin composition, while significantly reducing the activation energy of the reaction between the epoxy groups and the curing agent (dicyandiamide derivative), thereby shortening the curing time and improving production efficiency. Furthermore, lower curing temperatures reduce energy consumption and prevent damage to the substrate from high temperatures. By selecting imidazole derivatives with different substituents as imidazole accelerators, the properties of the pore-filling resin composition can be precisely designed. For example, 2-ethyl-4-methylimidazolium can effectively improve the heat resistance and mechanical strength of the cured pore-filling resin composition; 2-phenyl-4,5-dihydroxymethylimidazolium, containing a benzene ring and hydroxymethyl group, can significantly enhance the resistance to humid heat and the adhesion to the substrate of the cured pore-filling resin composition; the long-chain alkyl group of 2-heptadecylimidazolium can enhance its compatibility in the pore-filling resin composition, reduce phase separation, and alleviate the curing stress of the pore-filling resin composition, achieving a toughening effect.

[0037] In some embodiments, the particle size D50 of the spherical silica is 1-5 μm, and the spherical silica is pretreated with a silane coupling agent.

[0038] Specifically, spherical silica, as an inorganic filler, can effectively reduce the coefficient of thermal expansion of the pore-filling resin composition, reduce internal stress, and improve hardness, modulus, and thermal conductivity. The particle size D50 of spherical silica is 1-5μm, which is beneficial for achieving low viscosity under high filling conditions, giving the pore-filling resin composition excellent flowability and filling properties before curing. Surface pretreatment of spherical silica with silane coupling agent can significantly improve the interfacial adhesion between the inorganic filler and the resin composition, prevent interfacial defects, and improve overall mechanical properties, moisture resistance, and reliability.

[0039] In some embodiments, the toughening agent includes at least one of core-shell structured rubber particles and carboxyl-terminated nitrile butadiene rubber (CTBN); the coupling agent includes at least one of γ-glycidoxypropyltrimethoxysilane and γ-aminopropyltriethoxysilane; the solvent includes at least one of propylene glycol methyl ether acetate (PMA) and diethylene glycol butyl ether acetate; and the remaining additives include at least one of silicone leveling agents and silicone dispersants.

[0040] Specifically, the addition of toughening agents such as core-shell rubber particles or carboxyl-terminated nitrile butadiene rubber (CTBN) effectively absorbs impact energy and prevents crack formation without significantly reducing the heat resistance and modulus of the pore-filling resin composition. This effectively improves the toughness of the cured pore-filling resin composition and prevents brittle cracking. The addition of coupling agents effectively enhances the interfacial bonding force between inorganic fillers and resin. The addition of solvents provides suitable evaporation rates and dissolving capabilities, giving the pore-filling resin composition good storage stability, leveling properties, and workability. The addition of silicone leveling agents and silicone dispersants ensures that the solid components of the pore-filling resin composition are non-agglomerated and uniformly dispersed, enabling the pore-filling resin composition to level uniformly before curing, which is beneficial for obtaining a smooth, flat, and depression-free cured surface.

[0041] Furthermore, the synergistic effect of toughening agents and inorganic fillers effectively reduces the curing shrinkage rate and coefficient of thermal expansion of the via-filling resin composition, ensuring good compatibility between the via-filling resin composition and the PCB substrate, avoiding in-hole cracks and delamination after thermal cycling, and giving the via-filling resin composition excellent heat resistance and mechanical strength.

[0042] Secondly, embodiments of the present invention provide a method for preparing a pore-filling resin composition, comprising the following steps: The resin components and toughening agents are mixed with a portion of the solvent, followed by the addition of inorganic fillers and coupling agents for dispersion and grinding. Finally, the curing system, other additives, and remaining solvent are added and mixed. The resin components include bisphenol A type epoxy resin, cyanate ester, naphthalene ring type epoxy resin, and / or biphenyl type epoxy resin. The inorganic fillers include spherical silica, aluminum hydroxide surface-treated with silane coupling agents, and / or boehmite. The curing system includes microencapsulated dicyandiamide derivative curing agent and imidazole accelerator.

[0043] In some embodiments, the following steps are specifically included: Prepare the ingredients: by weight. Resin components: 10-20 parts of bisphenol A type epoxy resin, 10-20 parts of cyanate ester, and 5-15 parts of naphthalene ring type epoxy resin and / or biphenyl type epoxy resin; Curing system: 10-20 parts of microencapsulated dicyandiamide derivative curing agent and 0.5-3 parts of imidazole accelerator; Inorganic filler: 15-30 parts of spherical silica, 5-10 parts of aluminum hydroxide and / or boehmite after surface treatment with silane coupling agent; The mixture contains 3-8 parts toughening agent, 0.5-2 parts coupling agent, 0.5-2 parts other additives, and 5-15 parts solvent; wherein the other additives include at least one of silicone leveling agent and silicone dispersant.

[0044] Premixing: Add the resin components, toughening agent and part of the solvent (about 1 / 2) to a stirred tank, and stir at 300-600 rpm for 20-40 minutes under the conditions of 40-60℃ and vacuum degree of -0.08 to -0.095 MPa until the mixture is uniform to obtain the premix of the pore-filling resin composition. Dispersion: Add inorganic filler and coupling agent to the premix of pore-filling resin composition, and disperse at 800-1200 rpm for 60-90 minutes under conditions of 50-70℃ and vacuum degree of -0.08 to -0.095 MPa until uniform dispersion is obtained to obtain a high viscosity slurry; Grinding: Grind the high-viscosity slurry using a three-roll mill or sand mill until the fineness is ≤15μm, forming a uniform and fine paste; Mixing and filtration: Transfer the ground paste back to the mixing vessel, add the curing system, other additives and remaining solvent, and stir at 400-800 rpm for 40-60 minutes under conditions of 30-50℃ and vacuum degree above -0.095 MPa until the mixture is uniform and the air bubbles are removed. Filter through a 200-400 mesh filter to obtain the pore-sealing resin composition.

[0045] Specifically, the bisphenol A type epoxy resin includes at least one of E-51 and E44, with E-51 preferably being at least one of Nanya 128 and Changchun 186L; the cyanate ester resin includes at least one of bisphenol E type cyanate and bisphenol A type cyanate, with bisphenol E type cyanate preferably being bisphenol E type cyanate from Yangzhou Tianqi; the naphthalene ring type epoxy resin is preferably HP-4032D from DIC (Japan); and the biphenyl type epoxy resin is preferably the NC-3000 series from Nippon Kayaku and Mitsubishi Chemical. At least one of the YX4000 series of chemical products; the microencapsulated dicyandiamide derivative curing agent is preferably at least one of the microencapsulated dicyandiamide derivative curing agents prepared in Preparation Examples 1-3; the imidazole accelerator is preferably at least one of 2-ethyl-4-methylimidazolium (2E4MZ) and 2-phenylimidazolium (2PZ); the spherical silica includes spherical silica surface-treated with a silane coupling agent, wherein the particle size D50 of the spherical silica surface-treated with a silane coupling agent is 1-5 μm, and the spherical silica surface-treated with a silane coupling agent is preferably the Q series from Suzhou Jinyi; the aluminum hydroxide surface-treated with a silane coupling agent is preferably Higilite H-42M from Showa Denko, Japan; the toughening agent includes at least one of core-shell structured rubber particles and carboxyl-terminated nitrile butadiene rubber (CTBN), wherein the core-shell structured rubber particles are preferably Kaneka Ace MX series from Kaneka Chemicals, Japan and Paraaloid from Dow Chemicals, USA. At least one of the EXL series; the coupling agent includes at least one of γ-glycidoxypropyltrimethoxysilane (KH-560) and γ-aminopropyltriethoxysilane (KH-550); the solvent includes at least one of propylene glycol methyl ether acetate (PMA) and diethylene glycol butyl ether acetate; the remaining additives include at least one of silicone leveling agents and silicone dispersants.

[0046] The features and performance of the present invention will be further described in detail below with reference to embodiments. It is to be understood that the following description is merely illustrative and not intended to limit the specific scope of the invention.

[0047] The microencapsulated dicyandiamide derivative curing agents used in the following examples and comparative examples were prepared according to the following method. Unless otherwise specified, other raw materials are commercially available products.

[0048] Preparation Example 1 A microencapsulated dicyandiamide derivative curing agent was prepared, wherein the core material was 1-phenyldicyandiamide and the wall material was polyurea.

[0049] Preparation method: Prepare the following raw materials: 1.5g emulsifier (PVA-1788), 150g deionized water, 10g core material dicyandiamide derivative (1-phenyldicyandiamide), 30g organic solvent (xylene), 5g monomer A (toluene diisocyanate) and 1.8g monomer B (ethylenediamine); Preparation of the aqueous phase: The emulsifier is dissolved in deionized water to obtain the aqueous phase; Preparation of the oil phase: The dicyandiamide derivative constituting the core material is dissolved or dispersed in an organic solvent, monomer A constituting the wall material is added and stirred evenly to obtain the oil phase; Emulsification: in 10000s -1 The oil phase was added to the aqueous phase at a high shear rate of 2 mL / min and emulsified to obtain an oil / water (O / W) emulsion. At this time, the dicyandiamide derivative of the core material was dispersed into tiny droplets. Interfacial polymerization: Monomer B, which can react with monomer A to form the wall material, is added dropwise to the emulsion. Monomer B diffuses to the interface of tiny droplets formed by the dispersion of the core material dicyandiamide derivative in the oil phase, and undergoes an interfacial polymerization reaction with monomer A to form the wall material polyurea. Post-processing: After filtration, washing and drying, microencapsulated dicyandiamide derivative curing agent is obtained.

[0050] Performance parameters: The microencapsulated dicyandiamide derivative curing agent prepared in Example 1 has a particle size D50 of 8 μm, a wall material coverage of 96% of the core material, and a wall material thermal response temperature of 102℃.

[0051] The raw materials and formulations for Preparation Example 2-3 are shown in Table 1. The preparation method for Preparation Example 2-3 is the same as that for Preparation Example 1. The performance parameters of Preparation Example 2-3 are shown in Table 2.

[0052] Table 1: Raw materials and proportions for preparation examples 1-3 Table 2: Performance parameters of preparation examples 1-3 By adjusting the types and ratios of monomers A and B, the thickness, mechanical strength, and thermal response temperature of the wall material of the microencapsulated dicyandiamide derivative curing agent can be precisely controlled. The dense, thermally responsive wall material physically isolates the dicyandiamide derivative at room temperature, effectively preventing viscosity increase caused by contact with resin components, thus providing excellent storage stability (room temperature storage period ≥ 3 months). At the thermal response temperature (100-120℃), the wall material becomes permeable or ruptures, rapidly releasing the encapsulated dicyandiamide derivative and allowing it to contact the resin components. Under the accelerating effect of imidazole accelerators, a curing reaction is initiated at the thermal response temperature (100-120℃), thereby achieving curing of the pore-filling resin composition at a lower temperature.

[0053] Example 1 A pore-sealing resin composition.

[0054] Preparation method: Raw materials prepared: By weight, 15 parts of bisphenol A epoxy resin (Nanya 128), 15 parts of cyanate ester (bisphenol E cyanate ester from Yangzhou Tianqi Materials), 10 parts of naphthyl ring epoxy resin (HP-4032D from DIC Japan), 20 parts of microencapsulated dicyandiamide derivative curing agent (Preparation Example 2), 1 part of imidazole accelerator (2-ethyl-4-methylimidazolium (2E4MZ)), 25 parts of spherical silica (spherical silica with a particle size D50 of 2 μm pretreated with silane coupling agent (Suzhou Jinyi Silicon Q060)), and aluminum hydroxide surface treated with silane coupling agent (Higilite from Showa Denko Japan). 5 parts of H-42M), 5 parts of toughening agent (core-shell structured rubber particles), 1 part of coupling agent (γ-glycidyl etheroxypropyltrimethoxysilane (KH-560)), 0.3 parts of silicone leveling agent (BYK-333 from BYK Chemicals), 0.2 parts of silicone defoamer (BYK-019 from BYK Chemicals), and 10 parts of solvent (propylene glycol methyl ether acetate (PMA)). Premix: Add the resin components, toughening agent and part of the solvent (about 1 / 2) into a planetary mixer, and stir at 500 rpm for 30 minutes at 50°C and vacuum degree -0.09 MPa until the mixture is uniform to obtain the premix of the pore-filling resin composition. Dispersion: Spherical silica and aluminum hydroxide surface-treated with silane coupling agent were added to the premix of pore-sealing resin composition, the temperature was raised to 60°C, and the mixture was dispersed at 1000 rpm for 80 minutes under the conditions of 60°C and vacuum degree -0.09 MPa until uniform dispersion was obtained to obtain a high viscosity slurry. Grinding: The high-viscosity slurry is ground three times through a three-roll mill or a sand mill until the fineness is measured to be 12μm, forming a uniform and fine paste; Mixing and filtration: Transfer the ground paste back to the planetary mixer, add the curing system, other additives and remaining solvent, and stir at 600 rpm for 50 minutes at 40°C and a vacuum of -0.098 MPa until the mixture is homogeneous and the air bubbles are removed. Filter through a 300-mesh filter to obtain the pore-sealing resin composition, and seal it in a brown bottle.

[0055] The raw materials and formulations for Examples 2-3 are shown in Table 3. The preparation methods for Examples 2-3 are the same as those for Example 1. Among them, the naphthalene ring epoxy resin is selected from HP-4032D of DIC (Japan), the biphenyl epoxy resin is selected from NC-3000 of Nippon Kayaku, the core-shell structure rubber particles are selected from MX153 of Kaneka (Japan), the carboxyl-terminated nitrile butadiene rubber (CTBN) is selected from Huntsman 1300X13, and the coupling agents are selected from KH-550 and KH-560 of Jiangsu Chenguang.

[0056] Table 3: Raw materials and proportions for Examples 1-3 Examples 4-12 and Comparative Examples 1-6 had their resin component ratios adjusted. The resin component formulations are shown in Table 4. The remaining formulations are the same as in Example 1. The preparation methods for Examples 4-12 and Comparative Examples 1-6 are the same as in Example 1.

[0057] Table 4: Resin components, raw materials, and proportions for Examples 1, 4-12, and Comparative Examples 1-6 Examples 13-16 and Comparative Example 7 had their curing system ratios adjusted. The formulations of the curing systems are shown in Table 5. The remaining formulations are the same as in Example 1. The preparation methods for Examples 13-16 and Comparative Example 7 are the same as in Example 1.

[0058] Table 5: Raw materials and proportions of the curing systems of Examples 1, 13-16 and Comparative Example 7 Examples 17-20 and Comparative Examples 8-11 had their ratio of spherical silica and toughening agent adjusted. The formulations of the spherical silica and toughening agent are shown in Table 6. The remaining formulations are the same as in Example 1. The preparation methods of Examples 17-20 and Comparative Examples 8-11 are the same as in Example 1.

[0059] Table 6: Raw materials and proportions of spherical silica and toughening agent in Examples 1, 17-20 and Comparative Examples 8-11 Comparative Example 12 A pore-sealing resin composition comprising: 20 parts of bisphenol A type epoxy resin (Nanya 128), 8 parts of unmicroencapsulated dicyandiamide curing agent (dicyandiamide), 0.5 parts of imidazole accelerator (2-methylimidazole), 40 parts of inorganic filler (heavy calcium carbonate), 1 part of coupling agent (γ-glycidyl etheroxypropyltrimethoxysilane (KH-560)), 0.3 parts of silicone leveling agent (BYK-333 from BYK Chemicals), 0.2 parts of silicone defoamer (BYK-019 from BYK Chemicals), and 10 parts of solvent (propylene glycol methyl ether acetate (PMA)).

[0060] Preparation method: Bisphenol A type epoxy resin, inorganic filler, coupling agent, silicone leveling agent and silicone defoamer are added to the solvent and stirred evenly. Then, unmicroencapsulated dicyandiamide curing agent and imidazole accelerator are added, ultrasonically dispersed for 60 minutes, and finally vacuum degassing for 10 minutes.

[0061] Performance tests of Examples 1-20 and Comparative Examples 1-12 The pore-filling resin compositions prepared in Examples 1-20 and Comparative Examples 1-12 were screen-printed into the through holes of FR-4 test plates with a pore size of 0.2 mm and a thickness of 1.0 mm. After curing under their respective curing conditions, standard test samples were prepared and their performance was tested. The test results are shown in Table 7.

[0062] The testing standards for each test are as follows: Curing temperature: Glass transition temperature and coefficient of thermal expansion: The test standard is GB / T 36800.2-2018 Plastics Thermomechanical Analysis (TMA) Part 2: Determination of linear coefficient of thermal expansion and glass transition temperature; Dielectric constant and dielectric loss: The test standard is GB / T 5597-1999 Test method for microwave complex dielectric constant of solid dielectrics, and the test frequency is 10 GHz; Fill density: The test standard is IPC TM-650 2.1.1 microsection method; Surface depressions: The test standard is the acceptability of IPC-A-600J CN printed circuit boards, and the test instrument is an optical profilometer. Heat resistance: The test standard is IPC-TM-650 2.6.8 thermal stress, with plated through holes, and the test temperature is 288℃; Adhesion: The test standard is GB / T 9286-2021 Cross-cut test for paints and varnishes; Solvent resistance: The standard test sample was immersed in isopropanol at 25°C for 2 hours to test its solvent resistance.

[0063] Table 7: Performance test results of Examples 1-20 and Comparative Examples 1-12 Regarding curing performance, as shown in Table 7, the via-filling resin compositions of Examples 1-20 can achieve complete curing within 40 minutes at 100-120°C. Compared with the traditional curing temperature of 170°C and curing time of 60 minutes in Comparative Example 12, the curing temperature is reduced by more than 50°C, the curing time is shortened, energy consumption is significantly reduced, and curing efficiency is improved. Simultaneously, it can adapt to the heat-sensitive substrates and components required for high-frequency, high-speed PCBs, avoiding the risk of thermal damage. Comparing the performance of Examples 1, 13-16, and Comparative Example 7, it is evident that insufficient imidazole accelerators reduce the heat resistance and solvent resistance of the cured via-filling resin compositions, while excessive imidazole accelerators reduce the glass transition temperature and increase dielectric loss. By adjusting the addition amounts of microencapsulated dicyandiamide derivative curing agent and imidazole accelerators to match the resin components, a high glass transition temperature, low dielectric loss, and excellent heat and solvent resistance are achieved in the cured via-filling resin compositions.

[0064] Regarding high-frequency dielectric properties, comparisons of Examples 1-12 and Comparative Examples 1-6 show that the blending of bisphenol A epoxy resin, cyanate ester, biphenyl epoxy resin, and / or naphthalene ring epoxy resin stabilizes the dielectric constant (Dk) and dielectric loss (Df) of the via-filling resin compositions in Examples 1-14 below 3.3. Comparative Example 4 shows that excessive naphthalene ring epoxy resin reduces the filling density of the cured via-filling resin composition, resulting in surface pores. Simultaneously, the coefficient of thermal expansion (CTE) increases, increasing the risk of high-frequency, high-speed PCB cracking at high temperatures. Comparisons of Examples 1, 17-20, and Comparative Examples 8-12 show that excessive spherical silica leads to increased dielectric loss in the cured via-filling resin composition, reduced filling density and adhesion, and incomplete filling resulting in pores. By precisely controlling the amount of compounded phenol A epoxy resin, cyanate ester, biphenyl epoxy resin and / or naphthalene ring epoxy resin, as well as the amount of spherical silica added, the high filling capacity of the pore-filling resin composition for deep pores (aspect ratio of 5:1 or higher) and the excellent high-frequency dielectric properties and low coefficient of thermal expansion of the cured pore-filling resin composition are achieved.

[0065] Regarding thermomechanical reliability, as shown in Examples 1-20 and Comparative Examples 1-12, insufficient addition of spherical silica increases the coefficient of thermal expansion (CTE), reduces the heat resistance of the cured pore-filling resin composition, and causes cracking during the 288°C heat resistance test. Similarly, insufficient addition of toughening agent also reduces the heat resistance of the cured pore-filling resin composition, while excessive addition increases dielectric loss (Df) and reduces dielectric properties. By controlling the amounts of spherical silica and toughening agent, a balance between low CTE and high toughness is achieved in the cured pore-filling resin composition, preventing cracking during the 288°C heat resistance test while maintaining low dielectric loss.

[0066] In summary, the pore-filling resin composition of the present invention, through the synergistic effect of resin components, solid system, spherical silica, and toughening agent, can be completely and rapidly cured within 30-50 minutes at 100-120°C. The cured product has a low dielectric constant (Dk≤3.3) and a low electrical loss factor (Df≤0.009), while also having a high glass transition temperature (Tg≥160°C) and a low coefficient of thermal expansion (CTE≤90 ppm / °C). Compared with traditional processes, it significantly reduces energy consumption and improves efficiency. Rapid curing at lower temperatures avoids thermal damage to heat-sensitive substrates and components in high-frequency and high-speed PCBs. It can be safely applied to temperature-sensitive substrates or substrates containing temperature-sensitive components, while also possessing excellent high-frequency dielectric properties and thermomechanical reliability, meeting the high requirements of high-frequency and high-speed materials in fields such as 5G and above communications and high-performance computing.

[0067] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A pore-filling resin composition, characterized in that, Based on parts by weight, it includes the following components: The resin component includes 10-20 parts of bisphenol A type epoxy resin, 10-20 parts of cyanate ester, and 5-15 parts of naphthyl ring type epoxy resin and / or biphenyl type epoxy resin. The curing system comprises 10-20 parts of microencapsulated dicyandiamide derivative curing agent and 0.5-3 parts of imidazole accelerator; wherein the microencapsulated dicyandiamide derivative curing agent comprises a core material and a wall material, the core material being a dicyandiamide derivative, and the wall material being a thermoresponsive polymer with a thermal response temperature of 100-120℃; Inorganic filler, wherein the inorganic filler comprises 15-30 parts of spherical silica, 5-10 parts of aluminum hydroxide and / or boehmite after surface treatment with silane coupling agent; 3-8 parts toughening agent, 0.5-2 parts coupling agent, 0.5-2 parts additives and 5-15 parts solvent.

2. The pore-filling resin composition according to claim 1, characterized in that, The cyanate ester includes at least one of bisphenol E cyanate ester and bisphenol A cyanate ester.

3. The pore-filling resin composition according to claim 1, characterized in that, The naphthalene ring type epoxy resin includes at least one of 2,7-dihydroxynaphthalene diglycidyl ether, 1,6-dihydroxynaphthalene diglycidyl ether, and naphthol type epoxy resin; the biphenyl type epoxy resin includes at least one of biphenyl diglycidyl ether compounds, biphenyl type phenolic epoxy resin, and biphenyl type aralkyl epoxy resin.

4. The pore-filling resin composition according to claim 1, characterized in that, The dicyandiamide derivative includes at least one of alkyl-substituted dicyandiamide, aromatic-substituted dicyandiamide, dicyandiamide condensed with urea, and dicyandiamide condensed with amine; the thermoresponsive polymer includes at least one of polyurethane, polyurea, and polyurethane-urea hybrid polymer.

5. The pore-filling resin composition according to claim 1, characterized in that, The microencapsulated dicyandiamide derivative curing agent was prepared by interfacial polymerization.

6. The pore-filling resin composition according to claim 1, characterized in that, The preparation of the microencapsulated dicyandiamide derivative curing agent includes the following steps: dissolving an emulsifier in deionized water to obtain an aqueous phase; dissolving or dispersing the dicyandiamide derivative constituting the core material in an organic solvent, adding monomer A constituting the wall material and stirring evenly to obtain an oil phase; mixing and emulsifying the oil phase and the aqueous phase to obtain an oil / water (O / W) emulsion; adding monomer B, which can react with monomer A to form the wall material, to the emulsion for interfacial polymerization to form the wall material; wherein, by weight, the ratio of the raw materials is: emulsifier: deionized water: dicyandiamide derivative: organic solvent: monomer A: monomer B = (1-2): (100-300): 10: (20-30): (5-8): (1-5).

7. The pore-filling resin composition according to claim 1, characterized in that, The imidazole accelerators include at least one of 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-dihydroxymethylimidazole, and 2-heptadecylimidazole.

8. The pore-filling resin composition according to claim 1, characterized in that, The spherical silica has a particle size D50 of 1-5 μm and is pretreated with a silane coupling agent.

9. The pore-filling resin composition according to claim 1, characterized in that, The toughening agent includes at least one of core-shell structured rubber particles and carboxyl-terminated nitrile butadiene rubber (CTBN); the coupling agent includes at least one of γ-glycidoxypropyltrimethoxysilane and γ-aminopropyltriethoxysilane; the solvent includes at least one of propylene glycol methyl ether acetate (PMA) and diethylene glycol butyl ether acetate; and the additives include at least one of silicone leveling agents and silicone dispersants.

10. A method for preparing a pore-filling resin composition, characterized in that, Includes the following steps: The resin components and toughening agents are mixed in a portion of the solvent, then inorganic fillers and coupling agents are added for dispersion and grinding, and finally the curing system, additives, and remaining solvent are added and mixed. The resin components include bisphenol A type epoxy resin, cyanate ester, naphthyl ring type epoxy resin, and / or biphenyl type epoxy resin; the inorganic fillers include spherical silica, aluminum hydroxide surface-treated with a silane coupling agent, and / or boehmite; and the curing system includes microencapsulated dicyandiamide derivative curing agent and imidazole accelerator.

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