Curing accelerators and methods for their preparation, cofferdam gels and their use

Abstract

The application provides a curing accelerator and a preparation method thereof, a cofferdam glue and application thereof, and belongs to the technical field of adhesives. The structural formula of the curing accelerator is shown as formula I. The curing accelerator provided by the embodiment of the application has a flexible silicone segment with a silicon-oxygen-silicon skeleton, which can enable the molecular structure of the curing accelerator to have a certain degree of freedom, and the flexible silicone segment has good compatibility with resin and other materials in the cofferdam glue. When applied to the cofferdam glue, the curing accelerator can improve the toughness of the cofferdam glue and improve the anti-cracking ability, thereby ensuring the reliability of the cofferdam glue. In addition, in the curing accelerator, the flexible silicone segment is grafted through an imidazole group, which can significantly reduce the reactivity of the imidazole group. After being applied to the cofferdam glue, the curing accelerator can improve the storage stability of the cofferdam glue and ensure the long-period operation of the cofferdam glue.

Description

Technical Field

[0001] This application relates to the field of adhesive technology, specifically to a curing accelerator and its preparation method, a damming adhesive and its application. Background Technology

[0002] Enclosure adhesives possess excellent sealing and corrosion resistance properties, making them widely used in fields such as electronic packaging. Based on their curing methods, enclosure adhesives are mainly divided into UV-cured and thermosetting enclosure adhesives. UV-cured enclosure adhesives feature fast curing rates and high automation, but their glass transition temperature is low, resulting in poor reliability and making them difficult to match with chip devices requiring high-temperature reflow support. Thermosetting enclosure adhesives offer higher glass transition temperatures and higher reliability, but single-component enclosure adhesives generally require low-temperature storage, exhibit poor long-term operational stability, and typically have curing temperatures above 150℃, resulting in poor curing stress and toughness.

[0003] In related technologies, stress is typically dispersed by adding rubber or block copolymers, thereby improving the toughness of the cofferdam adhesive. However, the addition of high molecular weight toughening agents can lead to compatibility issues, failing to meet the application requirements of the cofferdam adhesive under stringent reliability conditions. Summary of the Invention

[0004] The embodiments of this application provide a curing accelerator and its preparation method, a cofferdam adhesive and its application. The application of the curing accelerator in the cofferdam adhesive can improve toughness while ensuring good compatibility and improving the reliability of the cofferdam adhesive.

[0005] In a first aspect, embodiments of this application provide a curing accelerator, the structural formula of which is shown in Formula I:

[0006]

[0007] R1 and R2 are independently selected from any one of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted phenyl, substituted or unsubstituted propenyl, and substituted or unsubstituted epoxy; R3-R5 are independently selected from any one of hydrogen, substituted or unsubstituted alkyl, and substituted or unsubstituted phenyl.

[0008] The value of x ranges from 1 to 100, the value of y ranges from 1 to 100, and the value of n ranges from 1 to 5.

[0009] Optionally, the value of x ranges from 1 to 10, and the value of y ranges from 1 to 10.

[0010] Secondly, embodiments of this application provide a method for preparing a curing accelerator, used to prepare the curing accelerator as described above, comprising:

[0011] The silane coupling agent is dispersed in a first solvent, and the silane coupling agent is hydrolyzed to obtain a first solution; wherein the silane coupling agent has an imidazole group;

[0012] Hydroxy silicone oil is dissolved in a second solvent to obtain a second solution. The first solution and a surfactant are added to the second solution to cause the hydrolyzed silane coupling agent to undergo a condensation reaction with the hydroxy silicone oil to obtain a reaction solution.

[0013] The solvent in the reaction solution is removed, and after drying, a curing accelerator is obtained.

[0014] Optionally, dispersing the silane coupling agent in a first solvent to hydrolyze the silane coupling agent includes:

[0015] Disperse the silane coupling agent in anhydrous ethanol, adjust the pH to alkaline, add deionized water at a temperature of 40℃-50℃, and maintain for 2-3 hours to hydrolyze the silane coupling agent.

[0016] Optionally, the hydroxyl silicone oil is dissolved in a second solvent to obtain a second solution. The first solution and a surfactant are added to the second solution to cause a condensation reaction between the hydrolyzed silane coupling agent and the hydroxyl silicone oil, including:

[0017] Hydroxysilicone oil was dissolved in anhydrous ethanol, and the pH was adjusted to alkaline to obtain a second solution.

[0018] The surfactant and the first solution are added to the second solution and reacted at a temperature of 40℃-50℃ for 6-10 hours to allow the hydrolyzed silane coupling agent to undergo a condensation reaction with the hydroxyl silicone oil.

[0019] Optionally, the solvent in the reaction solution is removed and the solution is dried, including:

[0020] The reaction solution was subjected to vacuum distillation to remove the solvent from the reaction solvent, and then dried under vacuum.

[0021] Thirdly, embodiments of this application provide a containment adhesive comprising the following components by weight: 5-15 parts epoxy resin, 60-80 parts filler, 10-15 parts curing agent, 1-10 parts curing accelerator, 1-5 parts thixotropic agent, and 0.5-3 parts coupling agent.

[0022] The curing accelerator includes the curing accelerator described above, and / or the curing accelerator prepared by the method described above.

[0023] Optionally, the epoxy resin includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, naphthalene type epoxy resin, aminophenol type epoxy resin, aliphatic epoxy resin and biphenyl epoxy resin;

[0024] And / or, the molecular weight of the epoxy resin is less than or equal to 600;

[0025] And / or, the filler includes spherical silica with a particle size distribution of 1μm-100μm and an average particle size of 5μm-20μm;

[0026] And / or, the curing agent includes at least one of amine curing agents and acid anhydride curing agents;

[0027] And / or, the coupling agent includes at least one of epoxy coupling agents, amino coupling agents, aniline coupling agents, mercapto coupling agents and vinyl coupling agents;

[0028] And / or, the thixotropic agent includes at least one of fumed silica, organobentonite, and hydrogenated castor oil.

[0029] Optionally, the curing agent includes anhydride curing agents with a molecular weight of less than or equal to 500.

[0030] Fourthly, embodiments of this application provide the application of the cofferdam adhesive as described above in electronic device packaging.

[0031] The beneficial effects of the embodiments of this application are as follows:

[0032] In the embodiments of this application, a curing accelerator is provided for use in cofferdam adhesives. The curing accelerator has the structural formula shown in Formula I. Because the curing accelerator contains flexible organosilicon segments with a silicon-oxygen-silicon backbone, its molecular structure can achieve a certain degree of freedom. Furthermore, the flexible organosilicon segments have good compatibility with the resin and other materials in the cofferdam adhesive. When applied to the cofferdam adhesive, it can improve the toughness and crack resistance of the adhesive, thereby ensuring its reliability. In addition, by grafting imidazole groups onto the flexible organosilicon segments, the reactivity of the imidazole groups can be significantly reduced. When applied to the cofferdam adhesive, this improves its storage stability and ensures its long-term operational capability. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a comparison diagram of the aspect ratio of the cofferdam adhesive in different states in Example 1 and Comparative Example 1. Detailed Implementation

[0035] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific implementation methods described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0036] In a first aspect, embodiments of this application provide a curing accelerator for use in a containment adhesive, the curing accelerator having the structural formula shown in Formula I:

[0037]

[0038] R1 and R2 are independently selected from any one of hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted phenyl, substituted or unsubstituted propenyl, and substituted or unsubstituted epoxy; R3-R5 are independently selected from any one of hydrogen, substituted or unsubstituted alkyl, and substituted or unsubstituted phenyl.

[0039] The value of x ranges from 1 to 100, the value of y ranges from 1 to 100, and the value of n ranges from 1 to 5.

[0040] This application provides a curing accelerator for use in cofferdam adhesives. The curing accelerator has the structural formula shown in Formula I. Because it contains flexible organosilicon segments with a silicon-oxygen-silicon backbone, its molecular structure can achieve a certain degree of freedom. Furthermore, the flexible organosilicon segments have good compatibility with resins and other materials in the cofferdam adhesive. When applied to the cofferdam adhesive, it can improve the adhesive's toughness and crack resistance, thereby ensuring its reliability. In addition, by grafting imidazole groups onto the flexible organosilicon segments, the reactivity of the imidazole groups can be significantly reduced. When applied to the cofferdam adhesive, this improves its storage stability and ensures its long-term operational capability.

[0041] When R1 and R2 are any one of substituted or substituted alkyl groups, substituted or unsubstituted phenyl groups, substituted or unsubstituted propenyl groups, or substituted or unsubstituted epoxy groups, the number of carbon atoms is preferably 1 to 6. When R3-R5 are any one of substituted or unsubstituted alkyl groups and substituted or unsubstituted phenyl groups, the number of carbon atoms is preferably 1 to 6.

[0042] In some embodiments, the value of x ranges from 1 to 10, and the value of y ranges from 1 to 10.

[0043] In some embodiments, n = 2. That is, three alkylene groups are spaced apart between the imidazole group and the flexible organosilicon segment, which enables the flexible organosilicon segment to have a certain degree of freedom.

[0044] Secondly, embodiments of this application provide a method for preparing a curing accelerator, used to prepare the curing accelerator as described above, comprising:

[0045] The silane coupling agent is dispersed in a first solvent, and the silane coupling agent is hydrolyzed to obtain a first solution; wherein the silane coupling agent has an imidazole group;

[0046] Hydroxy silicone oil is dissolved in a second solvent to obtain a second solution. The first solution and a surfactant are added to the second solution to cause the hydrolyzed silane coupling agent to undergo a condensation reaction with the hydroxy silicone oil to obtain a reaction solution.

[0047] The solvent in the reaction solution is removed, and after drying, a curing accelerator is obtained.

[0048] In the preparation method of the curing accelerator provided in this application embodiment, the silane coupling agent, after hydrolysis, can form hydroxysilane and the corresponding alcohol. The hydroxysilane has active hydroxyl groups, which can undergo a condensation reaction with the hydroxyl groups in the hydroxyl silicone oil, thereby forming flexible organosilicon segments. Since the silane coupling agent has imidazole groups, it can graft imidazole groups onto the flexible organosilicon segments. Imidazole groups have a curing-promoting effect. Because they are grafted onto the flexible organosilicon segments, they can significantly reduce the reactivity of the imidazole groups. When applied to damming adhesives, this can improve the storage stability of the damming adhesive and ensure its long-term operational capability.

[0049] For example, the synthesis route of the curing accelerator provided in the embodiments of this application is shown in Formula II:

[0050]

[0051] In some embodiments, dispersing the silane coupling agent in a first solvent to hydrolyze the silane coupling agent includes:

[0052] Disperse the silane coupling agent in anhydrous ethanol, adjust the pH to alkaline, add deionized water at a temperature of 40℃-50℃, and maintain for 2-3 hours to hydrolyze the silane coupling agent.

[0053] Using anhydrous ethanol as the primary solvent facilitates its removal from the solution and allows for easy recovery. Under alkaline conditions, the hydrolysis of the silane coupling agent is more rapid, shortening the hydrolysis time. Setting the temperature between 40℃ and 50℃ ensures the stability of the hydrolysis reaction, improves its efficiency, and reduces side reactions.

[0054] During the hydrolysis process, continuous stirring at a speed of 300-400 rpm ensures sufficient contact between the silane coupling agent and water, contributing to the formation of more stable and homogeneous hydrolysis products. Deionized water can be added dropwise to maintain reaction stability, and the dropping rate can be controlled according to the reaction progress.

[0055] The pH can be adjusted to around 7.5 to ensure hydrolysis efficiency and stability while reducing side reactions such as condensation.

[0056] In some embodiments, hydroxyl silicone oil is dissolved in a second solvent to obtain a second solution, and a first solution and a surfactant are added to the second solution, followed by a reaction, including:

[0057] Hydroxysilicone oil was dissolved in anhydrous ethanol, and the pH was adjusted to alkaline to obtain a second solution.

[0058] The surfactant and the first solution are added to the second solution, and the reaction is carried out at a temperature of 40℃-50℃ for 6h-10h, so that the hydrolyzed silane coupling agent and hydroxy silicone oil undergo a condensation reaction.

[0059] The second solvent is also anhydrous ethanol, which facilitates its removal from the solution later and allows for easy recovery. During the reaction under alkaline conditions, water molecules readily lose protons to form hydroxide ions. These hydroxide ions can attack the silicon-oxygen bonds in the hydrolysis products of the silane coupling agent in the first solution, thereby improving the efficiency of the condensation reaction and ensuring its stability. The addition of surfactants improves dispersibility and stability, reduces agglomeration and sedimentation, and ensures stable reaction. Surfactants also accelerate the contact and mixing between components, thus promoting the reaction. Conducting the reaction at 40℃-50℃ balances reaction stability and rate. A reaction time of 6-10 hours ensures complete reaction, balancing product yield and production costs.

[0060] In some embodiments, removing the solvent from the reaction solution and drying it includes:

[0061] The reaction solution was subjected to vacuum distillation to remove the solvent from the reaction solvent, and then dried under vacuum.

[0062] Vacuum distillation can lower the boiling point of the solvent, reducing the risk of product decomposition or deterioration due to excessively high temperatures, and improving separation efficiency. Vacuum drying is even more efficient and can be carried out at lower temperatures, ensuring product stability.

[0063] For example, vacuum distillation is carried out at room temperature, with the pressure controlled at 1.5 kPa.

[0064] In some embodiments, the silane coupling agent includes at least one of N-(trimethoxysilylpropyl)imidazolium and N-[3-(triethoxysilyl)propyl]-4,5-dihydroimidazolium.

[0065] In some embodiments, the hydroxyl silicone oil includes at least one of silanol-terminated polydimethylsiloxane and hydroxyl-terminated phenyl silicone oil.

[0066] Thirdly, embodiments of this application provide a containment adhesive comprising the following components by weight: 5-15 parts epoxy resin, 60-80 parts filler, 10-15 parts curing agent, 1-10 parts curing accelerator, 1-5 parts thixotropic agent, and 0.5-3 parts coupling agent. The curing accelerator includes the curing accelerator described above, and / or a curing accelerator prepared by the method described above.

[0067] The cofferdam adhesive provided in this application includes the curing accelerator described above. Because the curing accelerator contains flexible organosilicon segments with a silicon-oxygen-silicon backbone, its molecular structure can achieve a certain degree of freedom. Furthermore, the flexible organosilicon segments have good compatibility with the resin and other materials in the cofferdam adhesive, improving its toughness and crack resistance, thereby ensuring its reliability. In addition, the grafting of imidazole groups onto the flexible organosilicon segments in the curing accelerator significantly reduces the reactivity of the imidazole groups, improving the storage stability of the cofferdam adhesive and ensuring its long-term operational capability. In other words, the cofferdam adhesive provided in this application has high latency and strong toughness.

[0068] Epoxy resin possesses excellent adhesion, corrosion resistance, and mechanical strength, ensuring the cofferdam adhesive exhibits superior physical and chemical properties. Fillers can increase or decrease costs and adjust performance; a higher filler ratio can improve the hardness and abrasion resistance of the cofferdam adhesive while reducing costs. Curing agents enable the cofferdam adhesive to cure under appropriate conditions. Thixotropic agents improve the rheological properties of the cofferdam adhesive, giving it higher viscosity in the vertical direction, allowing it to maintain its shape and prevent dripping during application.

[0069] In some embodiments, the epoxy resin includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, naphthalene type epoxy resin, aminophenol type epoxy resin, aliphatic epoxy resin and biphenyl epoxy resin.

[0070] Bisphenol A epoxy resins possess excellent adhesive properties and chemical resistance, ensuring the adhesion and corrosion resistance of the cofferdam adhesive. Bisphenol F epoxy resins exhibit good weather resistance and thermal stability, contributing to improved weather resistance and thermal stability of the cofferdam adhesive. Naphthalene-type epoxy resins offer good high-temperature resistance and mechanical strength, enhancing the high-temperature resistance, tensile strength, and tear strength of the cofferdam adhesive. Aminophenol-type epoxy resins offer good processing performance and flexibility. Aliphatic epoxy resins are lower in cost and release fewer volatile organic compounds during curing, making them more environmentally friendly. Biphenyl epoxy resins possess excellent electrical insulation and arc melting properties, improving the insulation performance of the cofferdam adhesive.

[0071] The cofferdam adhesive provided in this application embodiment can be selected from one or more of the above-mentioned epoxy resins as needed.

[0072] Among them, the epoxy resin can preferably be a biphenyl epoxy resin or an aliphatic epoxy resin with strong heat resistance to improve the high temperature resistance of the cofferdam adhesive.

[0073] In some embodiments, the molecular weight of the epoxy resin is less than or equal to 600. Low molecular weight epoxy resins offer better penetration and flowability. By ensuring the molecular weight of the epoxy resin added to the cofferdam adhesive is less than or equal to 600, the epoxy resin can penetrate more fully into various gaps and pores, ensuring close contact and strong adhesion between the cofferdam adhesive and the substrate. Simultaneously, good flowability makes the cofferdam adhesive easier to apply and spread during construction, improving construction efficiency and quality. Low molecular weight epoxy resins also have a faster curing speed, helping to reduce shrinkage and deformation during the curing process, ensuring the smoothness and stability of the cofferdam adhesive. Furthermore, low molecular weight epoxy resins also contribute to improving the flexibility and elasticity of the cofferdam adhesive, and are also less expensive.

[0074] In some embodiments, the filler comprises spherical silica with a particle size distribution of 1 μm-100 μm and an average particle size of 5 μm-20 μm.

[0075] Spherical silica possesses high hardness and strength, which can improve the hardness and abrasion resistance of the cofferdam adhesive. The particle size distribution of spherical silica, ranging from 1μm to 100μm, facilitates uniform dispersion of the silica within the cofferdam adhesive, forming an effective reinforcing phase and enhancing the overall strength of the adhesive. Spherical silica with an average particle size of 5μm to 20μm can enhance the tear resistance of the cofferdam adhesive. When the cofferdam adhesive is torn by external forces, the spherical silica particles can act as "anchors," fixing the tear within the adhesive and preventing its propagation.

[0076] Furthermore, spherical silica is a chemically stable inorganic material that can improve the corrosion resistance of the cofferdam adhesive. Spherical silica also has a high melting point, which can improve the heat resistance of the cofferdam adhesive.

[0077] Among them, spherical silica can also be grafted and modified silica. Depending on the application scenario and requirements of the cofferdam adhesive, the spherical silica can be grafted and modified to improve the performance of the cofferdam adhesive.

[0078] In some embodiments, the curing agent includes at least one of amine curing agents and acid anhydride curing agents. Amine curing agents can achieve curing by changing the polarity of the system through an addition reaction between amino and epoxy groups. Acid anhydride curing agents can achieve curing by neutralizing the acidic groups in the anhydride with the epoxy groups to form an ester structure, thereby forming a three-dimensional cross-linked structure.

[0079] In some embodiments, the curing agent is an anhydride-based curing agent with a molecular weight of less than or equal to 500. Products cured with anhydride-based curing agents exhibit high heat resistance and chemical corrosion resistance, helping to maintain stability under high temperature and chemical corrosion conditions. Furthermore, the curing reaction does not generate volatile organic compounds, resulting in good environmental friendliness. Anhydride-based curing agents with a molecular weight of less than or equal to 500 also possess good weather resistance and stability, helping to ensure the stability and durability of the containment adhesive. Additionally, the low molecular weight of anhydride-based curing agents reduces volatility, helping to decrease the emission of harmful gases during the curing process.

[0080] In some embodiments, the anhydride curing agent includes at least one of aromatic anhydride curing agents, alicyclic anhydride curing agents, long-chain aliphatic anhydride curing agents, and anhydride adduct curing agents.

[0081] Among them, alicyclic anhydride curing agents are preferred. The molecular structure of alicyclic anhydride curing agents does not contain benzene rings, so they have good weather resistance, and the products cured by alicyclic anhydride curing agents have good flexibility and heat resistance.

[0082] In some embodiments, the coupling agent includes at least one of epoxy coupling agents, amino coupling agents, aniline coupling agents, mercapto coupling agents, and vinyl coupling agents.

[0083] The main function of coupling agents in cofferdam adhesives is to enhance the adhesion and compatibility between materials, thereby improving the overall performance of the cofferdam adhesive.

[0084] In some embodiments, the coupling agent includes an epoxy-based coupling agent. Epoxy-based coupling agents have epoxy groups, which can react with functional groups such as hydroxyl and carboxyl groups in the resin to form chemical bonds, thereby improving the adhesion and heat resistance of the cofferdam adhesive, and thus enhancing its stability. Epoxy-based coupling agents exhibit good compatibility with epoxy resin systems and can react with hydroxyl groups on the silica surface, improving the hygrothermal properties of the cofferdam adhesive.

[0085] In addition, the coupling agent can also be a methylsilane coupling agent.

[0086] In some embodiments, the thixotropic agent includes at least one of fumed silica, organobentonite, and hydrogenated castor oil.

[0087] Fumed silica possesses high surface activity and a large number of silanol groups on its surface, which can be linked together through hydrogen bonding to form a silica network, resulting in thixotropic properties. When applied to cofferdam adhesives, fumed silica enhances the thixotropy of the adhesive, making it easier to flow under shear force and regain viscosity and shape stability after the shear force disappears. Organobentonite has good thickening, thixotropic, and suspension stability properties, which can improve the viscosity and thixotropy of cofferdam adhesives. Hydrogenated castor oil has a long-chain fatty acid structure in its molecules, which causes it to change viscosity under shear force, exhibiting good thixotropic properties. At the same time, hydrogenated castor oil can also improve the lubricity and wear resistance of cofferdam adhesives.

[0088] In some embodiments, the thixotropic agent is preferably fumed silica and / or organobentonite, which helps to ensure the high thixotropic and high aspect ratio properties of the cofferdam adhesive.

[0089] Fourthly, embodiments of this application provide the application of the cofferdam adhesive as described above in electronic device packaging.

[0090] By applying the cofferdam adhesive described above to electronic device encapsulation, good flexibility and latency can be ensured, guaranteeing encapsulation effectiveness while improving stability and reliability. Especially for high-end chip encapsulation, the cofferdam adhesive provided in this application embodiment can guarantee excellent stability and reliability.

[0091] The embodiments of this application are further illustrated below with reference to specific examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. Experimental methods in the following embodiments that do not specify specific conditions are generally performed according to the conditions recommended by the manufacturer.

[0092] It should be noted that, unless otherwise specified, all parts in the following embodiments and comparative examples are parts by mass.

[0093] Example 1

[0094] (1) Disperse 50 parts of N-(trimethoxysilylpropyl)imidazolium in anhydrous ethanol, turn on the stirrer, control the stirring speed at 300 r / min, adjust the pH value to 8, slowly add deionized water, and stir continuously for 2 h at a temperature of 40℃ to fully hydrolyze N-(trimethoxysilylpropyl)imidazolium to obtain the first solution.

[0095] (2) Dissolve 40 parts of low molecular weight silanol-terminated polydimethylsiloxane (trade number: Dow Corning PMX-0156) in anhydrous ethanol, adjust the pH to 8, add the phase transfer catalyst tetrabutylammonium bromide and the first solution while stirring, and continue stirring the reaction at 40°C for 8 hours to obtain the reaction solution.

[0096] (3) Under normal temperature conditions, the reaction solution is subjected to vacuum distillation to remove the solvent, and after vacuum drying, a curing accelerator is obtained; wherein, the pressure during vacuum distillation is set to 1.5 kPa;

[0097] (4) Add 6 parts of bisphenol F epoxy resin, 5 parts of biphenyl epoxy resin, 12 parts of phthalic anhydride, 0.5 parts of γ-glycidyl etheroxypropyltrimethoxysilane coupling agent, 1 part of fumed silica and 2 parts of organobentonite to the reactor in sequence and mix evenly. Stir for 1 hour to obtain the first mixture.

[0098] (5) Add 70 parts of spherical silica filler to the first mixture in four batches, stir and disperse for 1 hour, then add 2 parts of the curing accelerator prepared in step (3), stir for 0.5 hours, and obtain the damming adhesive.

[0099] Example 2

[0100] The difference between this embodiment and Embodiment 1 is that:

[0101] Step (4): 6 parts of bisphenol F epoxy resin, 5 parts of biphenyl epoxy resin, 12 parts of phthalic anhydride, 0.5 parts of γ-glycidyl etheroxypropyltrimethoxysilane coupling agent, 1 part of fumed silica and 2 parts of organobentonite are added to the reaction vessel in sequence and mixed evenly. Stir for 1 hour to obtain the first mixture.

[0102] The remaining conditions are the same as in Example 1.

[0103] Example 3

[0104] (1) Disperse 50 parts of N-[3-(triethoxysilyl)propyl]-4,5-dihydroimidazole in anhydrous ethanol, turn on the stirrer, control the stirring speed at 400 r / min, adjust the pH value to 8, slowly add deionized water, and continue stirring for 3 h at a temperature of 40℃ to fully hydrolyze N-[3-(triethoxysilyl)propyl]-4,5-dihydroimidazole to obtain the first solution;

[0105] (2) Dissolve 40 parts of hydroxyl-terminated phenyl silicone oil in anhydrous ethanol, adjust the pH to 8, add the phase transfer catalyst tetrabutylammonium bromide and the first solution while stirring, and continue stirring the reaction at 40°C for 8 hours to obtain the reaction solution.

[0106] (3) Under normal temperature conditions, the reaction solution is subjected to vacuum distillation to remove the solvent, and after vacuum drying, a curing accelerator is obtained; wherein, the pressure during vacuum distillation is set to 1.5 kPa;

[0107] (4) Add 6 parts of bisphenol F epoxy resin, 5 parts of biphenyl epoxy resin, 12 parts of phthalic anhydride, 0.5 parts of γ-glycidyl etheroxypropyltrimethoxysilane coupling agent, 1 part of fumed silica and 2 parts of organobentonite to the reactor in sequence and mix evenly. Stir for 1 hour to obtain the first mixture.

[0108] (5) Add 70 parts of spherical silica filler to the first mixture in four batches, stir and disperse for 1 hour, then add 2 parts of the curing accelerator prepared in step (3), stir for 0.5 hours, and obtain the damming adhesive.

[0109] Comparative Example 1

[0110] (1) Add 6 parts of bisphenol F epoxy resin, 5 parts of biphenyl epoxy resin, 12 parts of phthalic anhydride, 0.5 parts of γ-glycidyl etheroxypropyltrimethoxysilane coupling agent, 1 part of fumed silica and 2 parts of organobentonite to the reactor in sequence and mix evenly. Stir for 1 hour to obtain the first mixture.

[0111] (2) Add 70 parts of spherical silica filler to the first mixture in four batches, stir and disperse for 1 hour, and then add 2 parts of 2-methylimidazole.

[0112] Comparative Example 2

[0113] (1) Add 6 parts of bisphenol F epoxy resin, 5 parts of biphenyl epoxy resin, 12 parts of phthalic anhydride, 0.5 parts of γ-glycidyl etheroxypropyltrimethoxysilane coupling agent, 1 part by mass of fumed silica and 2 parts of organobentonite to the reactor in sequence and mix evenly. Stir for 1 hour to obtain the first mixture.

[0114] (2) Add 70 parts of spherical silica filler to the first mixture in four batches, stir and disperse for 1 hour, and then add 2 parts of imidazole shell accelerator (Asahi Kasei Corporation HX-3722).

[0115] The performance of the cofferdam adhesives in Examples 1-3 and Comparative Examples 1-2 was tested, and the test indicators and methods included:

[0116] (1) Viscosity measurement: The room temperature viscosity of the cofferdam adhesive T0 (initial state) and T3 (room temperature for three days) was tested using a DV2T HB viscometer. The temperature was controlled at room temperature, and the measurement was performed at a speed of 5 rpm. The viscosity value was obtained by reading the value after 60 seconds.

[0117] (2) Aspect Ratio Measurement: The aspect ratio of the cofferdam adhesive T0 (initial state) and T1 (room temperature for one day) was measured; the adhesive was applied using a screw valve, the substrate was a printed circuit board, the valve temperature was not set, and a three-stroke square-shaped cofferdam was constructed to measure the aspect ratio.

[0118] (3) Differential scanning calorimetry determination: The test was performed using a TA instrument. The program was set to heat from 30℃ to 300℃, with a heating rate of 10℃ / min, in air atmosphere. The initial reaction temperature and peak temperature were recorded.

[0119] (4) Bending test: The glue is cured into a block, and the block is polished to a length, width and thickness of 80mm*10mm*4.0mm. A universal testing machine is used to perform the bending test at a test rate of 5mm / min.

[0120] (5) Determination of elongation at break: The glue was cured into dumbbell-shaped strips and stretched using a universal testing machine at a stretching rate of 5 mm / min.

[0121] (6) High and low temperature cycling: The chip device is protected by a cofferdam adhesive and the device is encapsulated and cured. The device is pre-conditioned according to MSL3 in JEDES-STD-22 standard. The pre-conditioning conditions are constant temperature of 125℃ for 24 hours and aging chamber at 85℃ and 60%RH for 168 hours. Then, it is subjected to three high-temperature reflow soldering treatments. The reflow oven program is set to ensure that the device is heated at a temperature above 220℃ for 300 seconds. After the pre-conditioning, the device is placed in the temperature cycling test chamber of the environmental test equipment for TCT cycle of -55℃ to 125℃, with a cycle of 700 cycles. The presence of cracks in the cofferdam adhesive body around the device is observed with a microscope, and the number of cracks is used for evaluation.

[0122] The test results are shown in Table 1 and Figure 1 As shown:

[0123] Table 1. Performance parameters and reliability results for Examples 1-3 and Comparative Examples 1-2

[0124]

[0125] As shown in Table 1 and Figure 1As shown in Examples 1-3 and Comparative Example 1, it can be observed that the addition of the curing accelerator provided in this application significantly prolongs the room temperature stability of the cofferdam adhesive, significantly reduces its reactivity, maintains a stable aspect ratio without collapse, and achieves excellent workability with good latency and shape retention, while also being suitable for long-cycle assembly line operations. Compared to Comparative Example 2, the flexural modulus and elongation at break of Examples 1-3 are significantly increased, and the cofferdam adhesive exhibits excellent toughness.

[0126] As can be seen from the reliability results in Table 1, by using the curing accelerator provided in the embodiments of this application, the flexible silicone flexible segments are introduced into the cofferdam adhesive, which can effectively resist the generation of bulk cracks, release internal stress, and has good reliability.

[0127] In summary, the curing accelerator provided in this application, when applied to the cofferdam adhesive, enables the cofferdam adhesive to have high reliability and long-term storage stability, and will have broad application value and development prospects in the field of electronic device packaging.

[0128] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for preparing a curing accelerator, characterized in that, include: The silane coupling agent is dispersed in a first solvent, and the silane coupling agent is hydrolyzed to obtain a first solution; The silane coupling agent described herein has an imidazole group; Hydroxy silicone oil is dissolved in a second solvent to obtain a second solution. The first solution and a surfactant are added to the second solution to allow the hydrolyzed silane coupling agent to undergo a condensation reaction with the hydroxy silicone oil, resulting in a reaction solution. The solvent in the reaction solution is removed, and after drying, the curing accelerator is obtained.

2. The method for preparing the curing accelerator according to claim 1, characterized in that, The step of dispersing the silane coupling agent in a first solvent to hydrolyze the silane coupling agent includes: The silane coupling agent is dispersed in anhydrous ethanol, the pH is adjusted to alkaline, and deionized water is added at a temperature of 40℃-50℃. The mixture is kept at this temperature for 2-3 hours to allow the silane coupling agent to hydrolyze.

3. The method for preparing the curing accelerator according to claim 1, characterized in that, The process of dissolving hydroxyl silicone oil in a second solvent to obtain a second solution, and then adding the first solution and a surfactant to the second solution to cause the hydrolyzed silane coupling agent to undergo a condensation reaction with the hydroxyl silicone oil includes: The hydroxyl silicone oil was dissolved in anhydrous ethanol, and the pH was adjusted to alkaline to obtain the second solution; The surfactant and the first solution are added to the second solution, and the reaction is carried out at a temperature of 40℃-50℃ for 6h-10h, so that the hydrolyzed silane coupling agent and the hydroxyl silicone oil undergo a condensation reaction.

4. The method for preparing the curing accelerator according to claim 1, characterized in that, The process of removing the solvent from the reaction solution, followed by drying, includes: The reaction solution is subjected to vacuum distillation to remove the solvent, and then vacuum dried.

5. A type of cofferdam adhesive, characterized in that, It comprises the following components by weight: 5-15 parts epoxy resin, 60-80 parts filler, 10-15 parts curing agent, 1-10 parts curing accelerator, 1-5 parts thixotropic agent and 0.5-3 parts coupling agent; The curing accelerator includes the curing accelerator prepared by the method described in any one of claims 1-4.

6. The cofferdam adhesive according to claim 5, characterized in that, The epoxy resin includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, naphthalene type epoxy resin, aminophenol type epoxy resin, aliphatic epoxy resin and biphenyl epoxy resin; And / or, the molecular weight of the epoxy resin is less than or equal to 600; And / or, the filler comprises spherical silica, the particle size of which is distributed in the range of 1 μm to 100 μm and the average particle size is 5 μm to 20 μm; And / or, the curing agent includes at least one of amine curing agents and acid anhydride curing agents; And / or, the coupling agent includes at least one of epoxy coupling agents, amino coupling agents, aniline coupling agents, mercapto coupling agents and vinyl coupling agents; And / or, the thixotropic agent includes at least one of fumed silica, organobentonite, and hydrogenated castor oil.

7. The cofferdam adhesive according to claim 6, characterized in that, The curing agent includes anhydride curing agents, wherein the molecular weight of the anhydride curing agent is less than or equal to 500.

8. The application of the cofferdam adhesive as described in any one of claims 5-7 in the encapsulation of electronic devices.

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