Water-based impregnation liquid and preparation method and packaging insulation process thereof

Abstract

The invention discloses a water-based impregnation liquid and a preparation method and a packaging insulation process thereof, and belongs to the technical field of environment-friendly insulation materials. The water-based impregnation liquid comprises the following components in parts by weight: 40-60 parts of water-based resin, 30-50 parts of ultrapure water, 1-5 parts of a curing agent and a small amount of functional aids. A product with high stability and good permeability is successfully obtained by optimizing the ratio of a resin system to a curing agent and adopting key preparation steps of preheating raw materials, mixing and dispersing at a controllable speed, pre-diluting the curing agent and homogenizing at a high speed. According to the technical scheme, the technical bottlenecks of insufficient permeability, poor adhesive force and medium resistance, low long-term reliability and the like of the traditional water-based impregnation liquid are systematically solved, and an oily product can be completely replaced; and the high-reliability packaging insulation requirements of the fields of semiconductor packaging, electronic component chip packaging, automotive electronics, aerospace and the like on precision elements are met.

Description

Technical Field

[0001] This invention belongs to the field of environmentally friendly insulating materials technology, specifically relating to an aqueous impregnating liquid, its preparation method, and its encapsulation insulation process. Background Technology

[0002] Impregnating solutions (also known as permeating solutions or penetrating fluids) are liquid materials used to fill defects such as micropores, pinholes, and cracks in materials. After curing, they form a sealing layer, solving problems such as leakage, corrosion, or poor surface treatment. Traditionally, impregnating solutions often use organic solvents as the dispersion medium, and are called oil-based impregnating solutions. Although oil-based impregnating solutions have certain advantages in terms of permeability and drying speed, they have high volatile organic compound (VOC) content, are flammable and explosive, and cause serious pollution to the health of operators and the environment. With increasingly stringent global environmental regulations, the use of oil-based impregnating solutions is gradually being restricted.

[0003] To replace oil-based impregnating solutions, water-based impregnating solutions have emerged. Water-based impregnating solutions use water as the dispersion medium and have advantages such as low VOC, non-flammability, safety and environmental protection. Some water-based impregnating solution products already exist in the existing technology, such as water-based epoxy resin and water-based polyurethane, but they still have the following problems in practical applications: (1) Insufficient permeability: The surface tension of water-based systems is high, making it difficult to effectively penetrate into pores below the micrometer level; (2) High curing temperature: Some water-based resins require high-temperature curing and are not suitable for heat-sensitive components; (3) Poor adhesion and media resistance: The bonding force between the cured film layer and the substrate is insufficient, and it is easy to fail in a humid and hot environment; (4) Poor process adaptability: It has high requirements for the construction environment and slow drying speed, which affects production efficiency.

[0004] Patent application CN 104005237 A discloses an impregnation method for microfiber synthetic leather base fabric based on water-based resin. Its primary problem lies in incomplete hydrolysis during the alkali reduction process, easily generating residues that contaminate components. Furthermore, the poor uniformity of the cell structure leads to significant differences in insulation performance across different regions of the substrate. In addition, this technology has a cumbersome process, involving multiple steps such as impregnation, drying, alkali reduction, washing, and baking, resulting in a long production cycle and high energy consumption. Moreover, its limited solids content also restricts the effective penetration of the impregnation solution into the micron-sized pores.

[0005] Therefore, developing an aqueous impregnating liquid that combines high permeability, low-temperature curing, excellent adhesion, and good process adaptability, along with its efficient preparation method and encapsulation insulation process, has become a pressing technical problem to be solved in this field. Summary of the Invention

[0006] One of the objectives of this invention is to provide an aqueous impregnation solution that solves the problems of insufficient permeability, poor adhesion and media resistance of existing aqueous impregnation solutions.

[0007] The second objective of this invention is to provide a method for preparing the above-mentioned aqueous impurity, which is simple in process and suitable for industrial production.

[0008] The third objective of this invention is to provide an application process for the above-mentioned aqueous impurity solution.

[0009] The objective of this invention can be achieved through the following technical solutions: An aqueous impurity, by weight, comprises the following components: Water-based resin: 40-60 parts; Ultrapure water: 30-50 parts; Hardener: 1-5 parts; Defoamer: 0.1–0.5 parts; Leveling agent: 0.2–1 part; Film-forming aid: 1-3 parts; Antifreeze: 1-2 parts; Flexible chain extender: 0.5 to 1.5 parts.

[0010] Furthermore, the waterborne resin is one or more composite systems selected from waterborne epoxy resin, waterborne polyurethane, waterborne phenolic resin, and modified waterborne epoxy-organic silicone composite resin.

[0011] Furthermore, the waterborne epoxy resin has hydrophilic hydroxyl and epoxy groups on its molecular chain, and its epoxy value is 0.2-0.5 eq / 100g.

[0012] Furthermore, the molecular chain of the waterborne polyurethane contains hydrophilic amino and isocyanate groups, with the isocyanate group content being 3-6 wt%.

[0013] Furthermore, the waterborne phenolic resin has a hydroxyl content of 10-20 wt% and is formed by the condensation of phenol and formaldehyde under alkaline conditions.

[0014] Furthermore, the modified waterborne epoxy-organic silicone composite resin has hydrophilic hydroxyl groups, epoxy groups, and organosilicon segments on its molecular chain; the epoxy value is 0.25-0.45 eq / 100g; the organosilicon segment content is 8-15 wt%; and the viscosity at 25°C is 800-1200 mPa. s, water dispersibility ≥98%.

[0015] Furthermore, the modified waterborne epoxy-organic silicone composite resin is prepared by the following steps: S1. Add 80-100 parts of bisphenol A type epoxy resin (epoxy value 0.51eq / 100g) to a four-necked flask, heat to 85-95℃, stir at 200-300rpm, and purge with nitrogen for protection. S2. Slowly add 15-25 parts of KH-560 (γ-glycidyl etheroxypropyltrimethoxysilane) at a dropping rate of 1-2 drops / second. After the addition is complete, raise the temperature to 110-120℃ and keep the reaction at this temperature for 2-3 hours to obtain epoxy-organosilicon prepolymer. S3. Cool to 60-70℃, add 5-8 parts of diethanolamine, increase the stirring speed to 400-500 rpm, react for 1-1.5 h, and introduce hydrophilic hydroxyl groups. S4. Cool to 40-50℃, slowly add 30-40 parts of ultrapure water, reduce the stirring speed to 200-300 rpm, disperse for 30-45 minutes, and obtain a modified waterborne epoxy-organic silicone composite resin with a solid content of 50%-60%.

[0016] Furthermore, the curing agent is one of an amine curing agent and an isocyanate curing agent, preferably an aqueous isocyanate curing agent.

[0017] Furthermore, the defoamer is an organosilicone defoamer, and the leveling agent is an acrylic leveling agent.

[0018] Furthermore, the film-forming aid is an alcohol ether compound; the antifreeze is ethylene glycol; and the flexible chain extender is one of polyether adipate diol and polycarbonate diol.

[0019] A method for preparing an aqueous impurity includes the following steps: S1. Raw material pretreatment: Preheat the water-based resin to 30-40℃ and the ultrapure water to 25-35℃. S2. Mixing and dispersing: Add the water-based resin to the mixing tank, and slowly add ultrapure water while stirring at a low speed of 200-300 rpm, controlling the feeding speed to avoid splashing; S3. Adding curing agent: Dilute the curing agent with ultrapure water 2-3 times, and slowly add it to the system while stirring at 800-1000 rpm, and continue to disperse for 10-15 minutes; S4. Additives: Add defoamer, leveling agent, film-forming aid and antifreeze in sequence, gradually increase the stirring speed to 800-1200 rpm, disperse for 20-30 minutes until the system is uniform; S5. Inspection and Packaging: Filter to remove particulate matter, test viscosity, solid content, and pH value, and package after passing the test.

[0020] Furthermore, in S2, the feeding rate is 100-200 mL / min.

[0021] Furthermore, in S4, the dispersion temperature is 25-35℃.

[0022] An encapsulation and insulation process, using the aforementioned aqueous impregnating solution, includes the following steps: S1. Substrate pretreatment: Clean the substrate surface with an alkaline degreasing agent and dry with compressed air or an oven at 60-80℃. S2. Impregnation operation: Immerse the substrate completely in the impregnation solution and leave it for 5 to 15 seconds; S3. Excess impregnation liquid discharge: The substrate is squeezed using a gap roller to discharge excess impregnation liquid; the gap is 50% to 60% of the substrate thickness; S4. Curing treatment: Dry at 80-130℃ for 30-70 minutes to form a sealed insulating layer; S5. Optional post-treatment: including volume reduction treatment and secondary curing; The weight reduction treatment involves treating with a 0.5%–3% weak alkaline solution at 90°C for 30 minutes, and the secondary curing involves drying at 120–130°C for 30–35 minutes.

[0023] Furthermore, before the impregnation operation in S2, a vacuum pressurization step is also included: first, maintaining a vacuum environment of ≤-0.090Mpa for 10 to 15 minutes to expel air from the pores; then maintaining a pressure of ≥0.3Mpa for 30 to 60 minutes to allow the impregnating liquid to penetrate deeply.

[0024] The beneficial effects of this invention are: (1) The aqueous impregnation solution provided by the present invention uses ultrapure water as the main dispersion medium, combined with 1 to 3 parts of alcohol ether film-forming aid and 1 to 2 parts of ethylene glycol antifreeze. While ensuring low-temperature film-forming properties and storage stability, it fundamentally controls the VOC content to an extremely low level of ≤100 g / L, which is far lower than that of traditional oily impregnation solutions, thus achieving true environmental protection and operational safety.

[0025] (2) By using 40-60 parts of waterborne resin as the film-forming matrix and supplementing it with 1-5 parts of amine or isocyanate curing agent to form a crosslinking system, not only is the excellent electrical insulation and dielectric resistance of the cured film layer ensured, but the hydrophilicity and hydrophobic resistance of the final product are also balanced. The precise matching of 30-50 parts of ultrapure water with the amount of resin controls the viscosity of the system within a suitable impregnation range, giving it low surface tension characteristics, which can effectively penetrate into micropores at the 0.2 μm level. At the same time, the optimized curing system allows the product to be fully cured in a low-temperature range, avoiding damage to heat-sensitive components caused by high temperatures.

[0026] (3) The modified waterborne epoxy-organosilicon composite resin achieves the synergistic performance of "high adhesion + low dielectric loss" through the covalent bonding of epoxy groups and organosilicon segments: after curing, the adhesion of the film layer to silicon chips and metal substrates reaches level 0 in the cross-cut test, while the dielectric loss tanδ≤0.002@1MHz, breaking the contradiction of "high dielectric loss with strong adhesion and poor adhesion with low dielectric loss" in traditional waterborne resins. It can meet the requirement of "low signal attenuation" when semiconductor chips transmit high-frequency signals, and also ensure the firm bonding between the chip and heterogeneous substrates such as metal pins.

[0027] (4) In terms of the preparation process, by preheating the raw materials, low-speed stirring and controllable feeding speed, pre-dilution and medium-speed dispersion of the curing agent, and addition of additives and high-speed homogenization, it is ensured that each component, especially 0.1 to 0.5 parts of silicone defoamer and 0.2 to 1 part of acrylic leveling agent, can play a full and stable role, and finally obtain a bubble-free, uniform and stable product. The preparation method parameters are clear and reproducible. It can be adapted to different scenarios without changing the system, reducing the production switching cost and taking into account both industrial efficiency and precision packaging requirements.

[0028] (5) In encapsulation and insulation applications, the vacuum pressurization step, which can be used before impregnation, can forcefully expel pore air and drive the impregnation liquid to penetrate deeply, effectively solving the problem of insufficient penetration in aqueous systems. Subsequently, gap rollers are used for squeezing and draining, precisely controlling the film thickness and avoiding surface enrichment. After curing, selective reduction treatment and secondary curing can be performed to ensure that the formed sealing and insulating layer is dense and firm, exhibiting excellent adhesion and long-term reliability. This not only meets the requirements of automotive electronics and aerospace for the long-term stable operation of components, but also ensures that semiconductor chips do not experience performance degradation due to encapsulation failure during long-term use, realizing the application value of high reliability in multiple fields. Detailed Implementation

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0030] In some embodiments, an aqueous impregnating solution comprises, by weight, the following components: Waterborne resin: 40-60 parts; ultrapure water: 30-50 parts; curing agent: 1-5 parts; defoamer: 0.1-0.5 parts; leveling agent: 0.2-1 parts; film-forming aid: 1-3 parts; antifreeze: 1-2 parts; flexible chain extender: 0.5-1.5 parts.

[0031] If the water-based resin content is less than 40 parts, the resin content is too low, resulting in a discontinuous and poorly dense film after curing, leading to insufficient insulation, sealing, and mechanical strength; if it is more than 60 parts, the system viscosity is too high, the fluidity is poor, and the ability to penetrate micron-sized pores is severely affected.

[0032] The dosage of ultrapure water (30-50 parts) works synergistically with the resin dosage to determine the viscosity and solids content of the system. This range ensures that the viscosity is controlled within a suitable range for the impregnation process, while guaranteeing sufficient resin loading for effective sealing.

[0033] The dosage of 1 to 5 parts of curing agent is based on molar equivalent calculations and experimental verification with the active groups of the resin. Insufficient dosage will result in low crosslinking degree, incomplete curing, sticky film, poor strength, and poor solvent resistance; excessive dosage may damage the stability of the system due to excessive curing agent, or introduce too many hydrophilic groups, reducing the water resistance of the cured film.

[0034] 0.1 to 0.5 parts of silicone defoamer can effectively reduce the surface tension of the system, eliminate existing bubbles, and inhibit the generation of new bubbles.

[0035] A 0.2 to 1 part acrylic leveling agent can form a monolayer on the paint film surface, uniformly distributing surface tension and allowing the paint film to level before curing, thus avoiding defects such as orange peel and brush marks. This is crucial for forming a uniform, defect-free insulating protective layer.

[0036] One to three parts of alcohol ether film-forming aids, as temporary plasticizers, can soften resin particles, allowing them to fuse at lower temperatures to form a continuous and dense film, thereby achieving the technical effect of curing at lower temperatures and broadening the process window.

[0037] Adding 1 to 2 parts of ethylene glycol can lower the freezing point of the aqueous phase, preventing the impurity from freezing and demulsifying during low-temperature transportation or storage in winter, thus ensuring stable product performance.

[0038] 0.5 to 1.5 parts of flexible chain extender (polyether adipate diol or polycarbonate diol) reduce the difference in thermal expansion coefficients between the cured film and the chip passivation layer by adjusting the flexibility of the molecular chain, thereby reducing the risk of cracking under temperature cycling.

[0039] This technical solution systematically solves the technical bottlenecks of traditional aqueous impregnation solutions, such as insufficient permeability, poor adhesion and resistance to media, and low long-term reliability. It can completely replace oil-based products and meet the high reliability packaging and insulation requirements of precision components in fields such as semiconductor packaging, electronic component chip packaging (such as CPU, GPU, CMOS sensor packaging), automotive electronics, and aerospace. It is especially suitable for high-frequency semiconductor scenarios, can withstand a wide temperature range of -50~150℃, and has a dielectric loss tanδ≤0.002@1MHz, avoiding high-frequency signal attenuation.

[0040] In some embodiments, the waterborne resin is one or more composite systems selected from waterborne epoxy resin, waterborne polyurethane, waterborne phenolic resin, and modified waterborne epoxy-organic silicone composite resin.

[0041] All of the above resins can be water-based and can form a three-dimensional network structure through curing, providing the required insulation, chemical resistance, and mechanical strength. Among them, epoxy resin provides high hardness and adhesion, polyurethane provides elasticity, and phenolic resin provides heat resistance.

[0042] In some embodiments, the waterborne epoxy resin has hydrophilic hydroxyl and epoxy groups on its molecular chain, and an epoxy value of 0.2-0.5 eq / 100g.

[0043] The hydrophilic hydroxyl groups are key to ensuring stable dispersion in water; the epoxy groups are the active centers that react with the curing agent and achieve cross-linking and curing. The epoxy value of 0.2-0.5 determines the resin's reactivity and final cross-linking density. If the value is too low, curing is slow and the degree of cross-linking is insufficient; if the value is too high, the system stability is poor and the cured film is brittle.

[0044] In some embodiments, the molecular chain of the waterborne polyurethane has hydrophilic amino and isocyanate groups, and the isocyanate group content is 3-6 wt%.

[0045] Hydrophilic amino groups ensure water dispersibility; isocyanate groups (-NCO) are functional groups that react with polyols to cure. A content of 3-6 wt% balances the stability of the prepolymer with the curing reactivity; too low a content results in slow curing and a soft film; too high a content results in a short shelf life and poor processability.

[0046] In some embodiments, the waterborne phenolic resin has a hydroxyl content of 10-20 wt% and is formed by the condensation of phenol and formaldehyde under alkaline conditions.

[0047] The high hydroxyl content (10-20 wt%) is the basis for its water solubility and high reactivity. The thermosetting phenolic resin synthesized under alkaline conditions contains hydroxymethyl groups that can be further reacted, ensuring its ability to self-cur or react with a curing agent under heating conditions.

[0048] In some embodiments, the modified waterborne epoxy-organic silicone composite resin has hydrophilic hydroxyl groups, epoxy groups, and organosilicon segments on its molecular chain; the epoxy value is 0.25-0.45 eq / 100g; the organosilicon segment content is 8-15wt%; and the viscosity at 25°C is 800-1200 mPa. s, water dispersibility ≥98%.

[0049] Introduced through the ring-opening reaction of diethanolamine and epoxy groups, it can form hydrogen bonds with water molecules, significantly improving the dispersibility of the resin in water. It retains the skeletal structure and some unreacted epoxy groups from bisphenol A type epoxy resin, providing crosslinking sites for subsequent reactions with the curing agent, ensuring the formation of a three-dimensional network structure in the cured film, thus endowing it with excellent mechanical strength and electrical insulation. Introduced through the covalent bonding of KH-560 with epoxy resin, its high bond energy of the -Si-O- bonds gives the resin excellent high and low temperature resistance, and the low polarity of the organosilicon segments reduces the intermolecular forces, lowering the dielectric loss of the cured film to below 0.002@1MHz, solving the defects of traditional waterborne epoxy resins in terms of "poor temperature resistance and high high-frequency dielectric loss," and adapting to the high-frequency signal transmission requirements of semiconductor packaging.

[0050] Maintaining the epoxy value within this range balances crosslinking density and flexibility, ensuring the cured film retains good crack resistance while exhibiting high resistance to media. Within this range, the silicone segment content achieves uniform dispersion of silicone segments in the epoxy matrix, leveraging their low dielectric loss and temperature resistance advantages without compromising the epoxy's high adhesion properties; viscosity at 25℃: 800-1200 mPa. With a water dispersibility of ≥98%, this combination of parameters ensures that the impregnating liquid has both suitable flowability and long-term stable storage, meeting the dual requirements of industrial production and precision packaging.

[0051] In some embodiments, the modified waterborne epoxy-organic silicone composite resin is prepared by the following steps: S1. Add 80-100 parts of bisphenol A type epoxy resin (epoxy value 0.51eq / 100g) to a four-necked flask, heat to 85-95℃, stir at 200-300rpm, and purge with nitrogen for protection. Bisphenol A type epoxy resin with an epoxy value of 0.51 eq / 100g was selected to reserve sufficient active sites for subsequent reactions with KH-560 and diethanolamine; the temperature was raised to 85-95℃ to melt the resin, and stirring was carried out at 200-300 rpm with nitrogen protection to provide a stable reaction environment for uniform grafting of KH-560.

[0052] S2. Slowly add 15-25 parts of KH-560 (γ-glycidyl etheroxypropyltrimethoxysilane) at a dropping rate of 1-2 drops / second. After the addition is complete, raise the temperature to 110-120℃ and keep the reaction at this temperature for 2-3 hours to obtain epoxy-organosilicon prepolymer. The γ-glycidoxypropyl group of KH-560 undergoes a ring-opening reaction with the epoxy group of the epoxy resin at 110-120℃, grafting siloxane segments onto the epoxy backbone through covalent bonds to ensure uniform distribution of organosilicon segments; the dropping rate is controlled at 1-2 drops / second to avoid self-polymerization caused by excessively high local KH-560 concentration.

[0053] S3. Cool to 60-70℃, add 5-8 parts of diethanolamine, increase the stirring speed to 400-500 rpm, react for 1-1.5 h, and introduce hydrophilic hydroxyl groups. When the temperature is lowered to 60-70℃, the amino group of diethanolamine undergoes a ring-opening reaction with the remaining epoxy group, introducing hydrophilic hydroxyl groups; increasing the stirring speed to 400-500 rpm can accelerate the mass transfer of the reaction system and ensure that the hydroxyl groups are evenly distributed on the molecular chain.

[0054] S4. Cool to 40-50℃, slowly add 30-40 parts of ultrapure water, reduce the stirring speed to 200-300 rpm, disperse for 30-45 minutes, and obtain a modified waterborne epoxy-organic silicone composite resin with a solid content of 50%-60%.

[0055] Cool the temperature to 40-50℃ (to reduce the viscosity of the system and facilitate dispersion), slowly add ultrapure water and stir at 200-300 rpm to avoid introducing air bubbles with high-speed stirring; a dispersion time of 30-45 minutes ensures that the resin is stably dispersed in water as nano-sized particles, and the final solid content of 50%-60% can balance the concentration and flowability of the impregnation solution.

[0056] In some embodiments, the curing agent is one of an amine curing agent and an isocyanate curing agent, preferably an aqueous isocyanate curing agent.

[0057] Amines are commonly used in epoxy resins; isocyanates are effective for both epoxy and polyurethane. Waterborne isocyanates are preferred because they have good compatibility with a variety of resins, moderate curing speed, and can form strong, tough, and chemically resistant coatings, resulting in the best overall performance.

[0058] In some embodiments, the defoamer is a silicone defoamer and the leveling agent is an acrylic leveling agent.

[0059] Silicone defoamers have high defoaming efficiency in aqueous systems due to their extremely low surface tension; acrylic leveling agents have good compatibility with aqueous systems, significant leveling effect, and are less likely to produce side effects.

[0060] In some embodiments, the film-forming aid is an alcohol ether compound, the antifreeze agent is ethylene glycol, and the flexible chain extender is one of polyether adipate diol and polycarbonate diol.

[0061] Alcohol ethers are the most commonly used and highly effective film-forming aids in aqueous systems. Ethylene glycol is an economical and effective antifreeze agent.

[0062] In polyether-type adipate diols, the low bond energy and flexible bond angles of the polyether segments allow for free molecular chain rotation, imparting excellent flexibility to the cured film. The linear flexible chains of the adipate segments further reduce the molecular chain packing density, decreasing internal stress in the cured film and preventing film cracking due to substrate thermal shrinkage. In polycarbonate diols, the carbon bond polarity is higher than the ether bond but lower than the ester bond, retaining a degree of flexibility while the rigidity of the carbon bond enhances the curing film's resistance to media. The length of the linear methylene chain is controllable, allowing for precise matching of CTE requirements to different substrates by adjusting the chain length.

[0063] In some embodiments, a method for preparing an aqueous impregnating solution includes the following steps: S1. Raw material pretreatment: Preheat the water-based resin to 30-40℃ and the ultrapure water to 25-35℃. Proper preheating can reduce the viscosity of resin and water, making subsequent mixing and dispersion easier, reducing the impact on stirring stability caused by large temperature differences in materials, avoiding local agglomeration, and ensuring a uniform and stable dispersion.

[0064] S2. Mixing and dispersing: Add the water-based resin to the mixing tank, and slowly add ultrapure water while stirring at a low speed of 200-300 rpm, controlling the feeding speed to avoid splashing; Low-speed stirring and slow water addition are to achieve a smooth phase transition from the high-viscosity resin phase to the aqueous phase, and to prevent the resin particles from becoming coarse, unevenly dispersed, or even demulsified due to excessively rapid shearing or excessive water addition.

[0065] S3. Adding curing agent: Dilute the curing agent with ultrapure water 2-3 times, and slowly add it to the system while stirring at 800-1000 rpm, and continue to disperse for 10-15 minutes; Diluting the curing agent prevents it from reacting rapidly with the resin due to excessively high local concentrations, thus preventing the formation of gel particles. Medium-speed stirring and a specified time ensure that the diluted curing agent is fully and evenly dispersed throughout the resin system, laying the foundation for subsequent uniform curing.

[0066] S4. Additives: Add defoamer, leveling agent, film-forming aid and antifreeze in sequence, gradually increase the stirring speed to 800-1200 rpm, disperse for 20-30 minutes until the system is uniform; Sequential addition and high-speed dispersion ensure that trace additives are evenly distributed throughout the system, maximizing their effectiveness. Sufficient dispersion time is essential to achieving a final stable and homogeneous product.

[0067] S5. Inspection and Packaging: Filter to remove particulate matter, test viscosity, solid content, and pH value, and package after passing the test.

[0068] Filtration is crucial for removing mechanical impurities that may be introduced during the manufacturing process, especially for precision electronics applications. Testing key parameters ensures consistent performance across batches and meets impregnation process requirements.

[0069] In some embodiments, the feeding rate in step S2 is 100-200 mL / min.

[0070] This feeding rate range ensures that the aqueous phase is smoothly integrated into the resin phase, achieving a controllable phase transition and avoiding emulsion demulsification.

[0071] In some embodiments, the dispersion temperature in step S4 is 25-35°C.

[0072] This temperature range ensures effective diffusion and mixing of the additives while preventing excessively high temperatures from causing a pre-reaction between the curing agent and the resin, which could affect the product's storage stability and performance.

[0073] In some embodiments, an encapsulation insulation process using the aqueous impregnating solution includes the following steps: S1. Substrate pretreatment: Clean the substrate surface with an alkaline degreasing agent and dry with compressed air or an oven at 60-80℃. Clean to remove oil, dust and other obstructions to ensure the impregnation liquid can fully wet the substrate; dry to remove moisture to prevent it from mixing with the impregnation liquid or hindering penetration, and to avoid air bubbles caused by moisture vapor pressure during curing.

[0074] S2. Impregnation operation: Immerse the substrate completely in the impregnation solution and leave it for 5 to 15 seconds; Complete immersion ensures all surfaces are in contact with the liquid. A residence time of 5–15 seconds is an optimized value based on the viscosity of the impregnating liquid and the porosity of the substrate. Too short a time will result in insufficient penetration, while too long a time will be inefficient and may cause the substrate to swell.

[0075] S3. Excess impregnation liquid discharge: The substrate is squeezed using a gap roller to discharge excess impregnation liquid; the gap is 50% to 60% of the substrate thickness; Extrusion prevents excessive surface coating and excessively thick cured film, which can affect component heat dissipation or assembly, and even cause cracking or stickiness due to uneven curing rates inside and outside the packaging. A gap of 50% to 60% can effectively drain excess liquid outside the pores while ensuring that the impregnating liquid inside the pores is not completely squeezed out. This is a precise control parameter for achieving thin and uniform encapsulation.

[0076] S4. Curing treatment: Dry at 80-130℃ for 30-70 minutes to form a sealed insulating layer; The low-temperature curing range of 80-130℃ is particularly suitable for heat-sensitive electronic components. At this temperature and time, moisture evaporates, and the resin and curing agent fully cross-link and react to form a dense, tough, and insulating solid sealing layer.

[0077] S5. Optional post-treatment: including volume reduction treatment and secondary curing; The weight reduction treatment involves treating with a 0.5%–3% weak alkaline solution at 90°C for 30 minutes, and the secondary curing involves drying at 120–130°C for 30–35 minutes.

[0078] The reduction treatment (1%–3% weak alkaline solution, 90℃ for 30 minutes) and secondary curing (120–130℃ drying for 30–35 minutes) efficiently remove uncrosslinked small molecules from the surface of the cured film while avoiding corrosion of the semiconductor substrate. This improves the film's density and cleanliness, laying the foundation for subsequent performance stability. The 1%–3% weak alkaline concentration, 90℃ temperature, and 30-minute time avoid the problems of incomplete treatment with low-concentration weak alkaline solutions and excessive corrosion with high-concentration weak alkaline solutions, while also preventing defects such as slow reaction at low temperatures and porosity caused by boiling at high temperatures. The secondary curing process activates the residual active groups after the basic curing by moderately raising the temperature, promoting complete resin crosslinking. At the same time, it eliminates internal stress by utilizing the fluidity of molecular chains. The temperature of 120–130℃ for 30–35 minutes ensures crosslinking efficiency while avoiding the risk of high-temperature failure of semiconductor chips. The reduction treatment and secondary curing meet the dielectric resistance requirements of general industrial packaging and are also suitable for the high cleanliness, low damage, and high reliability requirements of semiconductor packaging, realizing technical value in multiple scenarios.

[0079] In some embodiments, before the impregnation operation of S2, a vacuum pressurization step is further included: first, maintaining a vacuum environment of ≤-0.090 MPa for 10 to 15 minutes to expel air from the pores; then maintaining a pressure of ≥0.3 MPa for 30 to 60 minutes to allow the impregnation liquid to penetrate deeply.

[0080] Vacuum extraction removes air from the pores, breaking the air resistance; pressurization utilizes the pressure difference as a driving force to powerfully propel the impregnating liquid into deeper and finer pores.

[0081] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0082] Example 1

[0083] 1. An aqueous impurity, comprising, by weight, the following components: Waterborne epoxy resin (epoxy value 0.3 eq / 100g): 50 parts; Ultrapure water: 40 parts; Water-based isocyanate curing agent: 2 parts; Organosilicon defoamer: 0.3 parts; Acrylic leveling agent: 0.5 parts; Alcohol ether film-forming aid: 2 parts; Ethylene glycol antifreeze: 1.5 parts; Polyether-type adipate diol flexible chain extender: 1 part.

[0084] 2. A method for preparing an aqueous impurity, comprising the following steps: S1. Raw material pretreatment: Preheat the waterborne epoxy resin to 35°C and the ultrapure water to 30°C. S2. Mixing and dispersing: Add the water-based epoxy resin to the mixing tank, and add ultrapure water at a speed of 150 mL / min while stirring at a low speed of 250 rpm. S3. Adding curing agent: Dilute the curing agent with ultrapure water by 2 times, add it slowly while stirring at 1000 rpm, and continue to disperse for 12 minutes; S4. Additives: Add defoamer, leveling agent, film-forming aid, antifreeze and flexible chain extender in sequence, increase stirring speed to 1000 rpm and disperse for 25 minutes; S5. Inspection and Packaging: After filtration, the viscosity is tested to be 1500 mPa·s, the solid content is 45%, and the pH is 7.2. Pack for later use.

[0085] 3. An encapsulation and insulation process using the aforementioned aqueous impregnation solution, comprising the following steps: S1. Substrate pretreatment: Clean the PCB board with an alkaline degreasing agent and dry it in an 80℃ oven for 15 minutes; S2. Immersion Operation: Immerse the PCB board completely in the immersion solution and leave it for 10 seconds; S3, Squeeze out excess liquid: Use gap rollers to squeeze out excess liquid; S4. Curing treatment: Curing in an oven at 120℃ for 50 minutes.

[0086] Example 2

[0087] The difference between this embodiment and Example 1 is that the waterborne epoxy resin is replaced with waterborne polyurethane (isocyanate group content 4.5 wt%), while the other raw materials, preparation process and encapsulation process remain the same as in Example 1.

[0088] Example 3

[0089] The difference between this embodiment and Example 1 is that the waterborne resin is a composite system of waterborne epoxy resin and waterborne phenolic resin (weight ratio 3:1), while the other raw materials, preparation process and encapsulation process remain the same as in Example 1.

[0090] Example 4

[0091] The difference between this embodiment and Embodiment 1 is that the amount of curing agent used is 3 parts, the curing temperature is adjusted to 100℃, and the remaining raw materials, preparation process and packaging process are the same as in Embodiment 1.

[0092] Example 5

[0093] The difference between this embodiment and Embodiment 1 is that a vacuum pressurization step is added before the impregnation operation in the encapsulation insulation process: vacuum at -0.095 MPa for 12 minutes, followed by pressurization at 0.4 MPa for 40 minutes. The remaining raw materials, preparation process, and subsequent processes are the same as in Embodiment 1.

[0094] Example 6

[0095] The difference between this embodiment and Example 1 is that 0.2 parts of nano-silica reinforcing filler are added, while the other raw materials, preparation process and packaging process remain the same as in Example 1.

[0096] Example 7

[0097] The difference between this embodiment and Example 1 is that waterborne polyurethane resin (isocyanate group content 5.0wt%) is used, and 1.0 part of plasticizer (dioctyl phthalate) is added, and the curing temperature is reduced to 85°C.

[0098] This embodiment is applicable to components that need to withstand a certain degree of deformation. The remaining preparation process and packaging technology are the same as in Embodiment 1.

[0099] Example 8

[0100] The difference between this embodiment and Example 1 is that 3.0 parts of aluminum nitride (AlN) thermally conductive filler (particle size 1-3 μm) are added.

[0101] This embodiment is applicable to scenarios requiring heat dissipation, such as power devices. The remaining raw materials, preparation process, and packaging technology remain the same as in Embodiment 1.

[0102] Example 9

[0103] 1. An aqueous impurity, comprising, by weight, the following components: Modified waterborne epoxy-organic silicone composite resin (organic silicone segment content 12wt%): 55 parts; Ultrapure water: 35 parts; Water-based isocyanate curing agent: 3 parts; Organosilicon defoamer: 0.3 parts; Acrylic leveling agent: 0.6 parts; Alcohol ether film-forming aid: 2 parts; Ethylene glycol antifreeze: 1.5 parts; Polyether adipate diol (flexible chain extender): 1 part.

[0104] 2. A method for preparing an aqueous impurity, comprising the following steps: S1. Raw material pretreatment: Preheat the modified waterborne epoxy-organic silicone composite resin to 32°C and the ultrapure water to 28°C. S2. Mixing and dispersing: Add the modified waterborne epoxy-organic silicone composite resin to the mixing tank, and add ultrapure water at a speed of 120 mL / min while stirring at a low speed of 250 rpm. S3. Adding curing agent: Dilute the curing agent with ultrapure water by 2 times, add it slowly while stirring at 1000 rpm, continue to disperse for 12 minutes, and control the temperature at 30℃ to avoid decomposition of the flexible chain extender; S4. Additives: Add defoamer, leveling agent, film-forming aid, antifreeze and flexible chain extender in sequence, increase stirring speed to 1000 rpm and disperse for 25 minutes; S5. Inspection and Packaging: After filtration, the viscosity is tested to be 1500 mPa·s, the solid content is 45%, and the pH is 7.2. Pack for later use.

[0105] 3. An encapsulation and insulation process using the aforementioned aqueous impregnation solution, comprising the following steps: S0. Semiconductor substrate pretreatment: The surface of the CMOS sensor chip was cleaned with ultrapure water 4 times, each time for 6 seconds, and then dried in a vacuum oven at 55℃ (vacuum degree -0.090Mpa) for 18 minutes. S1. Substrate pretreatment: Clean the chip surface with a weak alkaline degreasing agent with pH 8.5 and dry with compressed air; S2. Immersion Operation: Immerse the chip completely in the immersion solution and leave it for 10 seconds; S3, Extrusion and drainage: Extrusion is performed using a gap roller with a gap of 58% of the chip thickness; S4. Curing treatment: Stepped curing (80℃ / 20 minutes → 100℃ / 20 minutes → 120℃ / 10 minutes); S5. Post-treatment: Treat with 1% weak alkaline solution at 90℃ for 30 minutes, then cure again at 120℃ for 30 minutes.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 1 is that a commercially available solvent-based epoxy impregnation solution (solvent is xylene, VOC=350 g / L) was used, and the curing conditions were the same.

[0108] Comparative Example 2

[0109] The difference between this comparative example and Example 1 is that no curing agent was used, while the other raw materials and preparation process remained the same as in Example 1.

[0110] Comparative Example 3

[0111] The difference between this comparative example and Example 1 is that ordinary tap water (total hardness ≈ 150 mg / L) was used instead of ultrapure water, while the other raw materials and preparation process remained the same as in Example 1.

[0112] Comparative Example 4

[0113] The difference between this comparative example and Example 1 is that the curing temperature is 180°C, while the other raw materials and preparation process remain the same as in Example 1.

[0114] Comparative Example 5

[0115] The difference between this comparative example and Example 1 is that it does not contain leveling agents and defoamers, while the other raw materials and preparation process remain the same as in Example 1.

[0116] Comparative Example 6

[0117] Compared with Example 1, this comparative example differs in that the encapsulation and insulation process does not include a vacuum pressurization step, but only impregnation under normal pressure. The remaining raw materials, preparation process and subsequent processes are the same as in Example 1.

[0118] Comparative Example 7

[0119] This comparative example uses a commercially available general-purpose water-based acrylic impregnating solution, whose product instructions specify VOC < 120 g / L and curing conditions of 120℃ / 30 min.

[0120] Comparative Example 8

[0121] The difference between this comparative example and Example 1 is that the amount of ultrapure water was reduced to 25 parts, which increased the viscosity of the final system to 4500 mPa·s. The other raw materials and preparation process remained the same as in Example 1.

[0122] Performance testing

[0123] The impregnation solutions obtained in Examples 1-8 and Comparative Examples 1-8, as well as the substrates treated according to the corresponding processes, were subjected to performance tests. Porous powder metallurgy test pieces and PCB boards were used uniformly. The test standards and methods are as follows: 1. Environmental protection and safety: VOC content Test standard: GB / T 23985-2009 "Determination of Volatile Organic Compounds (VOCs) Content in Paints and Varnishes - Difference Method" 2. Core process performance: Permeability Test methods: The minimum permeable pore size was determined by the microporous membrane method; the penetration depth in the powder metallurgy specimen was observed by the slice method.

[0124] 3. Interface bonding performance: adhesion

[0125] Test standard: GB / T 9286-2021 Paints and Varnishes Cross-cut Test, Cross-cut Method (0-5 grades, 0 is the best)

[0126] 4. Water absorption rate: Tested according to HG / T 3856-2006 "Determination of Water Absorption Rate of Insulating Varnish Film"; 5. Softening coefficient: K= / ,in For dry compressive strength, It is the saturated compressive strength; 6. Electrical insulation and protection performance: volume resistivity Test Standard: GB / T 31838.2-2019 "Dielectric and resistive properties of solid insulating materials – Part 2: Resistive properties (DC method) – Volume resistivity and volume resistivity" The results are shown in Table 1: Table 1

[0127] As shown in Table 1, the VOC content of all Examples 1-9 of this invention is significantly lower than that of Comparative Example 1, demonstrating its core environmental value. Furthermore, its VOC content is also lower than or equal to that of Comparative Example 7, proving the optimization effect of the formulation in terms of environmental protection.

[0128] Example 5 exhibits optimal permeability (minimum permeable pore size 0.10 μm, penetration depth 185 μm), even surpassing the performance of the conventional oil-based product in Comparative Example 1. The difference in penetration depth between Example 1 and Comparative Example 6 reflects the excellent permeability inherent in the basic formulation of this invention (40-60 parts resin and 30-50 parts water to adjust the appropriate viscosity). The data demonstrate a significant synergistic effect between the "optimized low-viscosity formulation" and the "vacuum pressurization process."

[0129] The adhesion of Examples 1-7 of this invention all achieved an optimal grade 0, significantly better than Comparative Examples 1 and 7. Example 7 achieved low-temperature curing at 85°C while maintaining grade 0 adhesion, while Comparative Example 4 only achieved grade 1 adhesion. This result confirms that a curing system composed of 1-5 parts of waterborne isocyanate curing agent and 40-60 parts of waterborne resin can form a dense and tough cross-linked network at low temperatures of 80-130°C, thereby simultaneously achieving low-temperature curing and high adhesion, solving the problem that traditional waterborne products struggle to achieve both.

[0130] The low water absorption and high softening coefficient of the examples are far superior to those of the comparative examples. In particular, the softening coefficient of Example 5 is as high as 0.96, indicating that its cured film layer can maintain a very high strength retention rate after immersion in water, and has excellent long-term durability. The water absorption (0.6%) and softening coefficient (0.95) of Example 9 are both at the best level, which is mainly attributed to the hydrophobic effect of the organosilicon segments (8-15 wt%) in the modified waterborne epoxy-organic silicone composite resin and the release of internal stress in the film layer by the flexible chain extender, which significantly improves the long-term stability in humid and hot environments. In contrast, the softening coefficient of Comparative Example 2 is only 0.60, and the performance is seriously deteriorated, indicating that a complete cross-linking network is crucial for water resistance.

[0131] In terms of volume resistivity, the embodiments of the present invention are generally superior to Comparative Examples 1 and 7. This indicates that the cured film layer formed by the present invention has high density and excellent intrinsic insulation properties, meeting the stringent requirements of high-end electronic packaging for insulating materials.

[0132] The properties of Comparative Examples 2 and 5, especially adhesion, insulation, and reliability, deteriorated significantly. This indirectly confirms that every component in the formulation of this invention is indispensable. 1 to 5 parts of curing agent are the basis for forming the three-dimensional network structure; 0.1 to 0.5 parts of defoamer and 0.2 to 1 part of leveling agent are key to ensuring a defect-free, uniform, and dense film. The absence of any component will lead to the failure of the entire technical solution.

[0133] To construct a comparative logic of "existing technology → basic solution of this invention → optimized solution of this invention", dielectric loss test and temperature cycling test were additionally conducted on the most representative group to illustrate the progress of the overall solution of this invention.

[0134] 7. Dielectric loss test

[0135] Test standard: Refer to GB / T1409-2006 "Recommended methods for measuring the permittivity and dielectric loss factor of electrical insulation materials at power frequency, audio frequency and high frequency".

[0136] 8. Temperature cycling test

[0137] Test standard: Refer to JEDEC JESD22-A104D "Temperature Cycling Test Method"

[0138] The modified waterborne epoxy-organic silicone composite resin system provided in Example 9 of this invention exhibits a dielectric loss tangent (tanδ) as low as 0.0018 at 1 MHz, significantly superior to Example 1 (0.0045) and Comparative Example 7 (0.0085). This excellent high-frequency dielectric performance is mainly attributed to the low-polarity organic silicone segments (-Si-O-) introduced into its molecular chain. This structure effectively reduces the polarization relaxation intensity in alternating electric fields, thereby significantly reducing power loss. Therefore, this invention, through specific resin modification, effectively overcomes the technical deficiency of high dielectric loss in traditional waterborne insulating materials for high-frequency applications, providing a crucial material guarantee for achieving high-fidelity signal transmission in high-frequency semiconductor devices (such as CPUs and GPUs).

[0139] After undergoing 100 cycles of stringent temperature cycling from -40°C to 125°C, Example 9 exhibited excellent environmental stability. Its cured film showed no cracking, and the water absorption rate increased only slightly from 0.6% to 0.7%, while the dielectric loss remained stable (0.0020). This performance advantage is attributed to the synergistic effect of the flexible chain extender and the silicone-modified epoxy network: the flexible chain extender effectively regulates and absorbs the internal stress caused by the difference in thermal expansion coefficients between materials, while the dense silicone-epoxy crosslinked network constitutes a highly efficient hydrophobic barrier. Through the aforementioned synergistic effect, this invention systematically solves the reliability problems of water-based encapsulation materials, such as easy cracking and moisture resistance degradation under alternating temperature conditions, making it particularly suitable for automotive electronics and aerospace fields with stringent requirements for long-term service stability.

[0140] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. An aqueous impregnation solution, characterized by, By weight parts, including the following components: Water-based resin: 40-60 parts; Ultra-pure water: 30-50 parts; Curing agent: 1-5 parts; Defoaming agent: 0.1-0.5 parts; Leveling agent: 0.2-1 parts; Film forming aid: 1-3 parts; Antifreeze: 1-2 parts; Flexible chain extender: 0.5-1.5 parts.

2. The aqueous impregnation solution of claim 1, wherein The water-based resin is one or more composite systems of water-based epoxy resin, water-based polyurethane, water-based phenolic resin and modified water-based epoxy-silicone composite resin; The water-based epoxy resin has hydrophilic hydroxyl and epoxy groups on the molecular chain, and the epoxy value is 0.2-0.5 eq / 100g; The water-based polyurethane has hydrophilic amino and isocyanate groups on the molecular chain, and the isocyanate group content is 3-6 wt%; The water-based phenolic resin has a hydroxyl content of 10-20 wt%, which is obtained by condensation of phenol and formaldehyde under alkaline conditions.

3. An aqueous impregnation solution according to claim 2, wherein The modified water-based epoxy-silicone composite resin is prepared by the following steps: S1, add 80-100 parts of bisphenol A type epoxy resin to a four-necked flask, heat to 85-95℃, stirring speed 200-300 rpm, and protect with nitrogen; S2, slowly add 15-25 parts of KH-560, drop rate 1-2 drops / s, after drop completion, heat to 110-120℃, and keep for 2-3h to obtain epoxy-silicone prepolymer; S3, cool to 60-70℃, add 5-8 parts of diethanolamine, increase stirring speed to 400-500 rpm, and react for 1-1.5h to introduce hydrophilic hydroxyl groups; S4, cool to 40-50℃, slowly add 30-40 parts of ultra-pure water, reduce stirring speed to 200-300 rpm, and disperse for 30-45min to obtain modified water-based epoxy-silicone composite resin with solid content of 50%-60%.

4. The aqueous impregnation solution of claim 1, wherein The curing agent is one of amine curing agent and isocyanate curing agent; the defoaming agent is silicone defoaming agent; the leveling agent is acrylic leveling agent.

5. The aqueous impregnation solution of claim 1, wherein The film forming aid is alcohol ether compound; the antifreeze is ethylene glycol; and the flexible chain extender is one of polyether adipate diol and polycarbonate diol.

6. A method for preparing an aqueous impregnation solution, characterized by, For preparing the water-based impregnation liquid of any one of claims 1-5, comprising the following steps: S1, raw material pretreatment: preheat the water-based resin to 30-40℃ and the ultra-pure water to 25-35℃; S2, mixing and dispersing: add the water-based resin into a stirring barrel, slowly add the ultra-pure water under low speed stirring of 200-300 rpm, and control the feeding speed to avoid splashing; S3, curing agent addition: dilute the curing agent with ultra-pure water by 2-3 times, slowly add into the system under stirring of 800-1000 rpm, and continue to disperse for 10-15min; S4, aid addition: add the defoaming agent, leveling agent, film forming aid and antifreeze in sequence, gradually increase the stirring speed to 800-1200 rpm, and disperse for 20-30min until the system is uniform; S5, inspection and packaging: filter out the particulate matter, detect the viscosity, solid content and pH value, and package after passing the inspection.

7. The method of claim 6, wherein the aqueous impregnation solution is prepared by adding the water to the mixture of the water-soluble polymer and the water-soluble organic solvent, and then adding the water-soluble inorganic salt to the mixture. In S2, the feeding speed is 100-200 mL / min.

8. The method of claim 6, wherein the aqueous impregnation solution is prepared by adding the water to the mixture of the water-soluble polymer and the water-soluble organic solvent, and then adding the water-soluble inorganic salt to the mixture. The dispersion temperature in S4 is 25-35℃.

9. A process for encapsulating insulation, characterized by The water-based impregnating solution prepared by the preparation method of any one of claims 6-8 comprises the following steps: S1, substrate pretreatment: cleaning the surface of the substrate with an alkaline degreasing agent and drying with compressed air or in an oven at 60-80℃; S2, impregnation operation: completely immersing the substrate in the impregnating solution for 5-15 seconds; S3, extrusion and liquid discharge: extruding the substrate using a gap roller to discharge the excess impregnating solution; the gap is 50%-60% of the thickness of the substrate; S4, curing treatment: drying at 80-130℃ for 30-70 minutes to form a sealed insulation layer; S5, optional post-treatment: including weight reduction treatment and secondary curing; The weight reduction treatment is 0.5%-3% weak alkali solution at 90℃ for 30 minutes, and the secondary curing is drying at 120-130℃ for 30-35 minutes.

10. The encapsulation process of claim 9, wherein, Before the impregnation operation of S2, a vacuum pressurization step is further included: first maintaining at ≤-0.090 Mpa vacuum environment for 10-15 minutes to discharge the air in the pores; then maintaining at ≥0.3 Mpa pressure for 30-60 minutes to make the impregnating solution penetrate deeply.

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