Curing agent, preparation method thereof, epoxy plastic encapsulating material and epoxy plastic encapsulating body

Abstract

This application discloses a curing agent and its preparation method, an epoxy molding compound, and an epoxy molding body. The curing agent has the following structural formula: R is a straight-chain alkyl group with 2-4 carbon atoms, or an alkyl group with 2-4 carbon atoms containing a hydroxyl group, or an alkyl group with 2-4 carbon atoms containing a thioether group; R' is an alkyl group containing 3-8 carbon atoms and branched, or an ether group containing 2-8 carbon atoms and branched, or a cycloalkyl group containing 3-6 carbon atoms, or an aryl group containing 6-10 carbon atoms. The R' groups at both ends of the curing agent of this application contain a cyclic structure or branched chain, which has a steric hindrance effect. This can prevent the epoxy groups of the epoxy resin in the epoxy molding compound from approaching the reaction sites (amine groups) of the curing agent, thereby delaying the curing initiation reaction, making the curing reaction conditions more intense, and inhibiting the reactivity of the curing agent and epoxy resin at room temperature, thereby improving the storage stability of the epoxy molding compound.

Description

Technical Field

[0001] This application relates to the field of chip packaging technology, specifically to a curing agent and its preparation method, an epoxy molding compound, and an epoxy molding compound. Background Technology

[0002] In the field of advanced chip packaging technology, structures such as fan-out wafer-level packaging (FOWLP) and 2.5D / 3D integrated circuit packaging place more stringent demands on the performance of epoxy molding compounds. Liquid epoxy molding compounds (LMCs) typically use epoxy resin as a prepolymer, combined with reactive liquid curing agents (such as acid anhydrides or amines), high-filler spherical fused silica, and various functional additives. During curing, the resin and curing agent form a three-dimensional cross-linked network through addition or catalytic reactions, while the filler system effectively regulates the coefficient of thermal expansion and improves the mechanical properties of the material.

[0003] The currently widely used epoxy-amide-containing amine curing system faces several key technical bottlenecks in practical applications, mainly in the synergistic control of material rheological properties and reactivity. Excellent rheological properties usually depend on the use of low molecular weight or highly reactive curing components. These components are prone to inducing prepolymerization reactions during storage and transportation, leading to a sharp increase in the viscosity of the epoxy molding compound system and significantly affecting its storage stability. Summary of the Invention

[0004] This application provides a curing agent and its preparation method, an epoxy molding compound, and an epoxy molding body, aiming to solve the problem of poor storage stability in epoxy molding compound systems.

[0005] This application provides a curing agent, the curing agent having the following structural formula: ; Wherein, R is a straight-chain alkyl group with 2-4 carbon atoms, or an alkyl group containing hydroxyl groups with 2-4 carbon atoms, or an alkyl group containing thioether groups with 2-4 carbon atoms, or... ; R' is an alkyl group containing 3-8 carbon atoms and branched, an ether group containing 2-8 carbon atoms and branched, a cycloalkyl group containing 3-6 carbon atoms, or an aryl group containing 6-10 carbon atoms.

[0006] Optionally, in some embodiments of this application, R is... , , , , or ; The R' is , , , , , , , , or .

[0007] Optionally, in some embodiments of this application, R' is or ;or The R is , , or And R' is .

[0008] Optionally, in some embodiments of this application, R' is or ;or The R is or And R' is .

[0009] Optionally, in some embodiments of this application, R' is , , or ;or The R is or And R' is ;or The R is , , or And R' is .

[0010] Accordingly, this application also provides a method for preparing a curing agent, comprising: A curing agent is obtained by reacting dimethyl dicarboxylate with a chain terminator via an amide condensation reaction. The structural formula of the dimethyl dicarboxylate is as follows: R is a straight-chain alkyl group with 2-4 carbon atoms, or an alkyl group with 2-4 carbon atoms containing a hydroxyl group, or an alkyl group with 2-4 carbon atoms containing a sulfide group. ; The chain terminator has the following structural formula: R' is an alkyl group containing 3-8 carbon atoms and branched, an ether group containing 2-8 carbon atoms and branched, a cycloalkyl group containing 3-6 carbon atoms, or an aryl group containing 6-10 carbon atoms.

[0011] Optionally, in some embodiments of this application, the dimethyl dicarboxylate includes , , , , and One or more of the following; The chain terminator includes , , , , , , , , and One or more of them.

[0012] Optionally, in some embodiments of this application, the chain terminator includes and At least one of them; or The dimethyl dicarboxylic acid ester includes , , and At least one of the following, and the chain terminator includes .

[0013] Optionally, in some embodiments of this application, the chain terminator includes and At least one of them; or The dimethyl dicarboxylic acid ester includes and At least one of the following, and the chain terminator includes .

[0014] Optionally, in some embodiments of this application, the chain terminator includes , , and At least one of them; or The dimethyl dicarboxylic acid ester includes and At least one of the following, and the chain terminator includes ;or The dimethyl dicarboxylic acid ester includes , , and At least one of the following, and the chain terminator includes .

[0015] Optionally, in some embodiments of this application, the molar ratio of the chain terminator to the dimethyl dicarboxylate is greater than or equal to 2.2:1; and / or The temperature of the amide condensation reaction is 60℃-80℃, and the reaction time is 10h-20h.

[0016] Accordingly, this application also provides an epoxy molding compound, comprising: epoxy resin and the curing agent described above or a curing agent prepared by the method described above.

[0017] Optionally, in some embodiments of this application, the epoxy resin includes one or more of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, o-cresol epoxy resin, trimethylolpropane triglycidyl ether, and hydrogenated bisphenol A epoxy resin.

[0018] Optionally, in some embodiments of this application, inorganic fillers are also included; The inorganic filler includes at least one of fused silica and crystalline silica; and / or The inorganic filler is an inorganic filler modified with alkoxysilanes having primary amino, secondary amino, tertiary amino, epoxy, mercapto, alkyl, urea, and vinyl groups; and / or The inorganic filler has a particle size of 0.001 μm-100 μm; and / or The inorganic filler has a mass content of 60%-90% in the epoxy molding compound.

[0019] Optionally, in some embodiments of this application, a stress absorber is further included, said stress absorber comprising at least one of styrene-butadiene copolymer, styrene-butadiene copolymer derivatives, and organosilicon particles; and / or Also includes silane coupling agents; and / or It also includes a release agent, said release agent comprising one or more of linear saturated carboxylic acids, polyethylene wax, carnauba wax, stearic acid, and synthetic paraffin wax; and / or It also includes ion trapping agents, said ion trapping agents comprising one or more of cation trapping agents, anion trapping agents, and anion-cation trapping agents; and / or It also includes fumed silica, wherein the average particle size of the fumed silica is 5 nm to 40 nm.

[0020] Optionally, in some embodiments of this application, the molar ratio of epoxy groups in the epoxy resin to amine hydrogen groups in the curing agent is 1:(0.8-1.2); and / or It also includes inorganic fillers, stress absorbers, silane coupling agents, release agents, ion traps and fumed silica, wherein the mass ratio of the epoxy resin, the inorganic fillers, the stress absorbers, the silane coupling agents, the release agents, the ion traps and the fumed silica is (5-15):(75-90):(0.1-5):(0.1-1.5):(0.1-1.5):(0.1-1):(0.5-5).

[0021] Accordingly, this application also provides an epoxy molding compound formed by curing the aforementioned epoxy molding compound.

[0022] The R' groups at both ends of the curing agent of this application contain cyclic structures or branches, which have a steric hindrance effect. They can prevent the epoxy groups of the epoxy resin in the epoxy molding compound from approaching the reaction sites (amine groups) of the curing agent, thereby delaying the curing initiation reaction and making the curing reaction conditions more intense (higher curing temperature and longer curing time). This achieves the inhibition of the reactivity of the curing agent and epoxy resin at room temperature, thereby improving the storage stability of the epoxy molding compound. Attached Figure Description

[0023] 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.

[0024] Figure 1 This is the structural formula of the curing agent provided in the exemplary embodiments of this disclosure; Figure 2 This is the 1H NMR spectrum of the curing agent provided in Embodiment 1 of this disclosure. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] The currently widely used epoxy-amide-amine curing system exhibits high reactivity during subsequent thermal processing such as dispensing and compression molding. This high reactivity causes the epoxy molding compound to rapidly crosslink at low temperatures, significantly shortening the gel window and the working window. This results in defects such as incomplete filling and porosity, severely impacting the integrity of the encapsulation structure, leading to device failure and subsequent reliability issues. Furthermore, this system presents inherent contradictions in curing kinetics control. Highly reactive curing agents chosen to meet the rapid curing requirements of efficient production often have unpredictable reaction characteristics, leading to stress buildup. These curing agents not only exhibit vigorous reactions at the target curing temperature but also maintain high reactivity at lower processing temperatures, meaning even small fluctuations in process parameters can cause significant changes in the curing rate. This temperature-sensitive, non-ideal curing behavior narrows the actual production process window (gel time), significantly reducing the process tolerance of the encapsulation process and posing a serious challenge to improving encapsulation yield.

[0027] This application provides a curing agent and its preparation method, an epoxy molding compound, and an epoxy molding body. These are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative and do not impose numerical requirements or establish an order. Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0028] This application provides a curing agent, the curing agent having the following structural formula: ; Wherein, R is a straight-chain alkyl group with 2-4 carbon atoms, or an alkyl group containing hydroxyl groups with 2-4 carbon atoms, or an alkyl group containing thioether groups with 2-4 carbon atoms, or... ; R' is an alkyl group containing 3-8 carbon atoms and branched, an ether group containing 2-8 carbon atoms and branched, a cycloalkyl group containing 3-6 carbon atoms, or an aryl group containing 6-10 carbon atoms.

[0029] The curing agent of this application has cyclic structures or branches at both ends of its R' groups, which have steric hindrance effects. This can prevent the epoxy groups of the epoxy resin in the epoxy molding compound from approaching the reaction sites (amine groups) of the curing agent, thereby delaying the curing initiation reaction and making the curing reaction conditions more intense. This achieves the inhibition of the reactivity of the curing agent and epoxy resin at room temperature, thereby improving the storage stability of the epoxy molding compound. The curing agent of this application is a short-chain amine curing agent containing amide bonds with fully terminated chain. It has a low initial viscosity, which allows the epoxy molding compound to flow into advanced narrow-gap (e.g., <50μm) encapsulation structures, thereby reducing voids and unfilled areas.

[0030] It is understandable that the secondary amine groups at both ends of the curing agent are the main functional groups that react with the epoxy groups. The secondary amine groups have low reactivity, and their curing usually requires certain heating conditions. Furthermore, the steric hindrance effect of the R' group can slow down the room temperature reaction rate between the curing agent and the epoxy groups, thereby improving the storage stability of the curing agent and extending its service life.

[0031] It is understandable that the connection key in the parentheses of R and R' is their connection point.

[0032] Optionally, in some embodiments of this application, the alkyl group containing 3-8 carbon atoms and having a branched chain and the ether group containing 2-8 carbon atoms and having a branched chain have branches that are independently methyl and ethyl, respectively.

[0033] It is understandable that alkyl groups containing 3-8 carbon atoms and branched chains, and ether groups containing 2-8 carbon atoms and branched chains, can have one or two branches.

[0034] Optionally, in some embodiments of this application, R is... , , , , or .

[0035] Optionally, in some embodiments of this application, R' is , , , , , , , , or .

[0036] Optionally, in some embodiments of this application, R' is or ;or The R is , , or And R' is Thus, by using R' groups with low steric hindrance, or by combining R' groups with highly reactive R groups, the epoxy groups of epoxy molding compounds can react rapidly with the curing agent at lower temperatures.

[0037] It is understandable that, such as Contains sulfide group, It exhibits the ortho-amine effect, thus possessing high activity.

[0038] Optionally, in some embodiments of this application, R' is or ;or The R is or And R' is Therefore, by using R' groups with high steric hindrance, or by combining R' groups with low-activity R groups, the epoxy groups of the epoxy molding compound need to react with the curing agent at a higher temperature. This can improve the storage stability of the epoxy molding compound and extend its service life.

[0039] Optionally, in some embodiments of this application, R' is , , or ;or The R is or And R' is ;or The R is , , or And R' is Thus, by using R' groups with moderate steric hindrance; or a combination of R' groups with low steric hindrance and low-activity R groups; or a combination of R' groups with high steric hindrance and high-activity R groups, the epoxy groups of epoxy molding compounds can react with the curing agent at a suitable temperature, thereby expanding the application scenarios of epoxy molding compounds.

[0040] It is understandable that by controlling the R groups in the curing agent, the curing reactivity and the structure and properties of the final cured network can be regulated. By independently designing and combining the chain length that determines viscosity, the R groups that determine basic reactivity, and the R' groups that fine-tune reactivity with the gel time, it is possible to decouple the "low viscosity" and "slow reaction" characteristics while maintaining low viscosity. This allows for precise "matrix-like" control of the curing behavior (as shown in Table 1), enabling the material to have a long gel time at the process temperature and rapid curing at higher temperatures. Different combinations of R groups and different R' groups can give epoxy molding compounds different curing temperatures and different properties, as shown in Table 1.

[0041] Table 1. Curing temperature and performance of epoxy molding compounds with different R-group and different R'-group combinations.

[0042] This application provides a method for preparing a curing agent, comprising: A curing agent is obtained by reacting dimethyl dicarboxylate with a chain terminator via an amide condensation reaction. The structural formula of the dimethyl dicarboxylate is as follows: R is a straight-chain alkyl group with 2-4 carbon atoms, or an alkyl group with 2-4 carbon atoms containing a hydroxyl group, or an alkyl group with 2-4 carbon atoms containing a sulfide group. ; The chain terminator has the following structural formula: R' is an alkyl group containing 3-8 carbon atoms and branched, an ether group containing 2-8 carbon atoms and branched, a cycloalkyl group containing 3-6 carbon atoms, or an aryl group containing 6-10 carbon atoms.

[0043] Optionally, in some embodiments of this application, the dimethyl dicarboxylate includes , , , , and One or more of them.

[0044] Optionally, in some embodiments of this application, the chain terminator includes , , , , , , , , and One or more of them.

[0045] It is understandable that by changing the structure of the chain terminator, the curing curve of the epoxy resin can be adjusted, so that the epoxy molding compound can not only meet the storage and process requirements, but also quickly complete the curing under the set curing conditions, thereby improving production efficiency.

[0046] Optionally, in some embodiments of this application, the chain terminator includes and At least one of them; or The dimethyl dicarboxylic acid ester includes , , and At least one of them, and the chain terminator is Thus, by using R' groups with low steric hindrance, or by combining R' groups with highly reactive R groups, the epoxy groups of epoxy molding compounds can react rapidly with the curing agent at lower temperatures.

[0047] Optionally, in some embodiments of this application, the chain terminator includes and At least one of them; or The dimethyl dicarboxylic acid ester includes and At least one of the following, and the chain terminator includes Therefore, by using R' groups with high steric hindrance, or by combining R' groups with low-activity R groups, the epoxy groups of the epoxy molding compound need to react with the curing agent at a higher temperature. This can improve the storage stability of the epoxy molding compound and extend its service life.

[0048] Optionally, in some embodiments of this application, the chain terminator includes , , and At least one of them; or The dimethyl dicarboxylic acid ester includes and At least one of the following, and the chain terminator includes ;or The dimethyl dicarboxylic acid ester includes , , and At least one of the following, and the chain terminator includes Thus, by using R' groups with moderate steric hindrance; or a combination of R' groups with low steric hindrance and low-activity R groups; or a combination of R' groups with high steric hindrance and high-activity R groups, the epoxy groups of epoxy molding compounds can react with the curing agent at a suitable temperature, thereby expanding the application scenarios of epoxy molding compounds.

[0049] Optionally, in some embodiments of this application, the molar ratio of the chain terminator to the dimethyl dicarboxylate is greater than or equal to 2.2:1, for example, it can be 2.2:1, 2.3:1, 2.4:1, 2.5:1, etc. Thus, by using a 10% excess of the chain terminator, the dimethyl dicarboxylate can react completely and achieve complete chain termination.

[0050] Optionally, in some embodiments of this application, the temperature of the amide condensation reaction is 60℃-80℃, for example, it can be 60℃, 62℃, 64℃, 66℃, 68℃, 70℃, 72℃, 74℃, 76℃, 78℃, 80℃, etc., and the reaction time of the amide condensation reaction is 10h-20h, for example, it can be 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, etc.

[0051] Optionally, in some embodiments of this application, the amide condensation reaction is carried out by stirring at 200 rpm to 300 rpm, for example, 200 rpm, 210 rpm, 220 rpm, 230 rpm, 240 rpm, 250 rpm, 260 rpm, 270 rpm, 280 rpm, 290 rpm, 300 rpm, etc.

[0052] Optionally, in some embodiments of this application, after the amide condensation reaction, the reaction further includes: concentrating the reacted liquid under vacuum at 100°C for 6 hours. This removes methanol or water, reducing the probability of introducing methanol or water into the epoxy molding compound.

[0053] This application provides an epoxy molding compound, comprising: epoxy resin and the curing agent described above.

[0054] Optionally, in some embodiments of this application, the epoxy resin includes one or more of bifunctional and trifunctional epoxy resins with a viscosity of 300 Pa·s to 700 Pa·s, such as 300 Pa·s, 400 Pa·s, 500 Pa·s, 600 Pa·s, 700 Pa·s, etc.

[0055] As an example, epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenolic epoxy resin.

[0056] Optionally, in some embodiments of this application, the epoxy resin includes one or more of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, o-cresol epoxy resin, trimethylolpropane triglycidyl ether, and hydrogenated bisphenol A epoxy resin.

[0057] Optionally, in some embodiments of this application, an inorganic filler is further included, comprising at least one of fused silica and crystalline silica. Thus, the inorganic filler can reduce the coefficient of thermal expansion of the epoxy molding compound, thereby matching the coefficient of thermal expansion of the epoxy molding compound with that of the chip and substrate, and reducing the probability of thermal stress failure.

[0058] It is understandable that the surface of inorganic fillers can be unmodified or modified with a modifier.

[0059] Optionally, in some embodiments of this application, the inorganic filler is an inorganic filler modified with alkoxysilanes having primary, secondary, tertiary amine, epoxy, mercapto, alkyl, urea, and vinyl groups. This enhances the interaction between the inorganic filler and the epoxy resin, thereby increasing the mechanical strength of the cured epoxy molding compound.

[0060] As an example, modifiers such as KBM-403, KBE-9103, and KBM-573 manufactured by Shingoku Chemical Industry Co., Ltd. can be selected.

[0061] Optionally, in some embodiments of this application, the inorganic filler is an inorganic filler modified with an epoxy group-containing alkoxysilane. This can improve the compatibility between the inorganic filler and the epoxy resin.

[0062] Optionally, in some embodiments of this application, the particle size of the inorganic filler is 0.001 μm-100 μm, for example, it can be 0.001 μm, 0.01 μm, 0.1 μm, 1 μm, 10 μm, 100 μm, etc. This allows control over the viscosity and related properties of the epoxy molding compound for application in advanced encapsulation.

[0063] Optionally, in some embodiments of this application, the particle size of the inorganic filler is 0.001μm-75μm, for example, it can be 0.001μm, 0.01μm, 0.1μm, 1μm, 10μm, 75μm, etc.

[0064] Optionally, in some embodiments of this application, the inorganic filler has a mass content of 60%-90% in the epoxy molding compound, for example, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc.

[0065] Optionally, in some embodiments of this application, the inorganic filler has a mass content of 75%-90% in the epoxy molding compound, for example, it can be 75%, 77%, 80%, 82%, 85%, 87%, 90%, etc.

[0066] Optionally, in some embodiments of this application, a stress absorber is also included, comprising at least one of styrene-butadiene copolymer, a derivative of styrene-butadiene copolymer, and organosilicon particles. In this way, the stress absorber actively absorbs and disperses stress, thereby protecting the fragile chip and solder joints.

[0067] Optionally, in some embodiments of this application, the stress absorber includes one or more of acrylonitrile-butadiene-styrene copolymer, epoxy-terminated styrene-butadiene-styrene block copolymer, epoxidized styrene-butadiene-styrene block copolymer, styrene-butadiene rubber, styrene-butadiene rubber, carboxyl-terminated liquid nitrile butadiene rubber (CTBN), and hydroxyl-terminated liquid nitrile butadiene rubber (HTBN).

[0068] Optionally, in some embodiments of this application, the stress absorber includes at least one of terminal epoxy-terminated styrene-butadiene-styrene block copolymer and styrene-butadiene rubber.

[0069] Optionally, in some embodiments of this application, a silane coupling agent is also included. In this way, the silane coupling agent can bridge the inorganic filler and the epoxy resin, enhance interfacial adhesion, and prevent delamination.

[0070] As an example, the silane coupling agent may be selected from γ-(2,3-epoxypropoxy)propyltrimethoxysilane, trimethoxyphenylsilane, 3-aminopropyltriethoxysilane, 3-(isobutenoyloxy)propyltrimethoxysilane, vinyltrimethoxysilane, (3-aminopropyl)triethoxysilane, 3-aminopropyltrimethoxysilane, γ-anilinepropyltrimethoxysilane, γ-anilinepropyltriethoxysilane, γ-aniline Propylmethyldimethoxysilane, γ-anilinopropylmethyldiethoxysilane, γ-anilinopropylethyldiethoxysilane, γ-anilinopropylethyldimethoxysilane, γ-anilinomethyltrimethoxysilane, γ-anilinomethyltriethoxysilane, γ-anilinomethyldimethoxysilane, γ-anilinomethyldiethoxysilane, γ-anilinomethylethyldiethoxysilane, γ-anilinomethylethyldimethoxysilane.

[0071] Optionally, in some embodiments of this application, a release agent is also included, comprising one or more of linear saturated carboxylic acids, polyethylene wax, carnauba wax, stearic acid, and synthetic paraffin wax. Thus, the release agent allows the cured epoxy molding compound to better separate from the mold, thereby ensuring production efficiency and product appearance.

[0072] As an example, polyethylene wax can be either oxidized or non-oxidized polyethylene wax.

[0073] Optionally, in some embodiments of this application, the number-average molecular weight of the linear saturated carboxylic acid is 550-800.

[0074] Optionally, in some embodiments of this application, an ion trapping agent is also included, comprising one or more of a cation trapping agent, anion trapping agent, and anion-cation trapping agent. Thus, the ion trapping agent can adsorb and immobilize harmful migrating ions (such as Cl-). - Na + This prevents circuit corrosion and improves long-term reliability.

[0075] It is understandable that migrating ions (such as Cl-) in epoxy molding compounds... - Na + The source of this risk may be from raw materials, the production process, or environmental factors. For example, inorganic fillers in raw materials (such as silica) may contain sodium (Na) during mining or processing. + Cl - Impurities such as flame retardants (e.g., brominated epoxy resin may contain halide ions), coupling agents, and colorants in raw materials may carry ionic impurities; during the production process, stainless steel equipment may release metal ions (e.g., sodium hydroxide). + (From glassware or pipes), additive ions may leach from plastic pipes; insufficient purity of water or organic solvents used in production may introduce sodium. + Cl - wait, The workshop environment or personnel operations may introduce salt substances (such as sodium in sweat). + Cl - When molding compound absorbs moisture, airborne pollutants (such as NaCl in sea salt) may dissolve and permeate the material. If the packaging material has poor sealing or is substandard, it may introduce ionic pollutants. During chip mounting, bonding, molding, and other processes, ions from molds, cleaning agents (containing chlorine solvents), or flux may migrate into the molding compound.

[0076] Optionally, in some embodiments of this application, fumed silica is also included, wherein the average particle size of the fumed silica is 5 nm to 40 nm. Thus, fumed silica can adjust the system viscosity and related physical properties of the epoxy molding compound, regulate the rheological properties of the epoxy molding compound, prevent inorganic filler sedimentation and epoxy resin flow, and maintain the uniform dispersion of each component in the epoxy molding compound for application in advanced encapsulation.

[0077] Optionally, in some embodiments of this application, a colorant is also included.

[0078] Optionally, in some embodiments of this application, the mass ratio of the epoxy resin, the inorganic filler, the curing agent, the stress absorber, the silane coupling agent, the release agent, the ion trapping agent, the fumed silica, and the colorant is (5-15):(75-90):(2-10):(0.1-5):(0.1-1.5):(0.1-1.5):(0.1-1):(0.5-5):(0-0.5).

[0079] Optionally, in some embodiments of this application, the molar ratio of epoxy groups in the epoxy resin to amine groups in the curing agent is 1:(0.8-1.2), for example, it can be 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, etc. Thus, by adjusting the molar ratio of epoxy groups in the epoxy resin to amine groups in the curing agent, the rigidity (modulus) and toughness, heat resistance and stress, as well as curing speed and storage stability of the epoxy molding compound can be balanced to meet the needs of different encapsulation structures and reliability requirements.

[0080] Understandably, when the molar ratio of epoxy groups in the epoxy resin to amine hydrogen groups in the curing agent is less than 1:1, the crosslinking density of the epoxy molding compound is low, resulting in lower modulus and brittleness after curing. This helps alleviate internal stress, improves crack resistance, and extends the working time. When the molar ratio of epoxy groups in the epoxy resin to amine hydrogen groups in the curing agent is greater than 1:1, it ensures that the epoxy groups in the epoxy resin are fully reacted and consumed. This is beneficial for improving the curing completeness, heat distortion temperature, and glass transition temperature of the epoxy molding compound, giving it superior heat resistance and rigidity, and reducing long-term aging problems caused by unreacted groups.

[0081] This application provides a method for preparing an epoxy molding compound, comprising: mixing epoxy resin and the above-mentioned curing agent to obtain an epoxy molding compound.

[0082] Optionally, in some embodiments of this application, mixing the epoxy resin and the curing agent described above includes: Epoxy resin, stress absorber, mold release agent, and ion scavenger are mixed to obtain the first mixture. Inorganic filler, fumed silica, and colorant are mixed to obtain a second mixture; After mixing the first mixture, the second mixture, and the curing agent, they are then mixed with a silane coupling agent to obtain an epoxy molding compound.

[0083] Understandably, stepwise mixing can improve the uniformity of material distribution and the efficiency and effectiveness of silane coupling agent interface modification. By mixing epoxy resin with additives (stress absorbers, release agents, ion scavengers) first, it can be ensured that a small amount of additive can be uniformly dispersed in the continuous epoxy resin matrix, avoiding local agglomeration or uneven dispersion caused by the subsequent addition of high-viscosity fillers. Premixing the three powders—inorganic filler, fumed silica, and colorant—can initially homogenize powders of different particle sizes and densities. In particular, it allows the extremely light and easily agglomerated fumed silica to adhere to the surface of large-particle inorganic filler, making it easier to disperse and wet when mixed with epoxy resin, preventing the formation of hard agglomerates that are difficult to disperse in the epoxy resin. First, mixing the first mixture, the second mixture, and the curing agent allows the epoxy resin to fully impregnate and coat all filler particles, forming a homogeneous premixed system. Finally, adding the silane coupling agent maximizes its "bridging" effect, enabling a more direct and effective reaction at the resin-filler interface, forming the strongest chemical bonds and thus improving the mechanical properties and moisture-proof reliability of the epoxy molding compound. If the silane coupling agent is added early with a large amount of powder, it may be over-adsorbed onto the powder surface and potentially "coated" or consumed during subsequent high-shear mixing and epoxy resin impregnation, reducing its efficiency.

[0084] Optionally, in some embodiments of this application, the mixing of the first mixture, the second mixture, the curing agent, and the silane coupling agent is carried out at 0-10°C.

[0085] It is understandable that by adding a curing agent and maintaining the mixture at a low temperature of 0-10°C, the curing reaction between the epoxy resin and the curing agent can be inhibited, thereby extending the pot life of the epoxy molding compound. This ensures that its viscosity will not increase significantly from the time it is produced until it is put into use for molding and encapsulation, and that its performance remains stable, thus ensuring the consistency of the molding and encapsulation process.

[0086] Accordingly, this application also provides an epoxy molding compound formed by curing the aforementioned epoxy molding compound.

[0087] It is understood that the epoxy molding compound of this application can be used in the field of chip packaging.

[0088] Example 1 A curing agent and its preparation method, comprising: 17.5 g of dimethyl dicarboxylate (structural formula: ) and 32.5 g chain terminator (structural formula is After mixing at a molar ratio of 1:2.2, the mixture was stirred at 75°C and 250 rpm for 16 hours, followed by vacuum concentration at 100°C for 6 hours. After the reaction was completed, it was confirmed that there was no residual methanol or water, yielding the curing agent (CA-Pen-IP), whose 1H NMR spectrum is shown below. Figure 2 (As shown).

[0089] An epoxy molding compound and its preparation method, comprising, by weight: (1) 8.90 parts of epoxy resin (bisphenol A diglycidyl ether, epoxy equivalent 187), 0.98 parts of stress absorber (carboxyl-terminated liquid nitrile rubber (CTBN)), 0.10 parts of release agent (carbamate), and ion scavenger were poured into a 5°C high-speed mixer and stirred at 500 rpm for 7.5 min to obtain the first mixture; (2) 75.25 parts of inorganic filler (silica filler surface-treated with silane coupling agent, maximum cut-off particle size: 53 μm) and 4.89 parts of fumed silica (nano silica, particle size range of 5~40 nm, specific surface area of ​​300±30 m²) were added. 2 / g), 0.10 parts of colorant (carbon black) were added to a high-speed mixer at 5℃ and stirred at 500rpm for 12 minutes to obtain the second mixture; (3) Mix the first mixture, the second mixture and 9.19 parts of curing agent (CA-Pen-IP) into a 5°C high-speed mixer and stir at 500 rpm for 4 min. Then adjust the speed of the high-speed mixer to 180 rpm and add 0.59 parts of silane coupling agent (γ-glycidyl oxypropyltrimethoxysilane). After the addition is complete, stir at 500 rpm for 20 min to obtain epoxy molding compound.

[0090] Example 2 This embodiment is basically the same as Example 1, except that the structural formula of dimethyl dicarboxylate in this embodiment is: The structural formula of the chain terminator is The resulting curing agent is CA-MPS-cHx.

[0091] Example 3 This embodiment is basically the same as Example 1, except that the structural formula of dimethyl dicarboxylate in this embodiment is: The structural formula of the chain terminator is The resulting curing agent is CA-Et-cHx.

[0092] Example 4 This embodiment is basically the same as Example 1, except that the structural formula of dimethyl dicarboxylate in this embodiment is: The structural formula of the chain terminator is The resulting curing agent was CA-MPS-Ph.

[0093] Example 5 This embodiment is basically the same as Example 1, except that the structural formula of dimethyl dicarboxylate in this embodiment is: The structural formula of the chain terminator is The resulting curing agent is CA-Et-tBu.

[0094] Example 6 This embodiment is basically the same as Example 1, except that the structural formula of dimethyl dicarboxylate in this embodiment is: The structural formula of the chain terminator is The resulting curing agent is CA-Et-Bn.

[0095] Example 7 This embodiment is basically the same as Example 1, except that the structural formula of dimethyl dicarboxylate in this embodiment is: The structural formula of the chain terminator is The resulting curing agent is CA-nBu-Ph.

[0096] Example 8 This embodiment is basically the same as Embodiment 1, except that the structural formula of the dimethyl dicarboxylate in this embodiment is: The structural formula of the chain terminator is The resulting curing agent is CA-PPA-cPe.

[0097] Example 9 This embodiment is basically the same as Embodiment 1, except that the structural formula of the dimethyl dicarboxylate in this embodiment is: The structural formula of the chain terminator is The resulting curing agent was CA-Pen-tBu.

[0098] Example 10 This embodiment is basically the same as Embodiment 1, except that the structural formula of the dimethyl dicarboxylate in this embodiment is: The structural formula of the chain terminator is The resulting curing agent is CA-Et-Ph.

[0099] Comparative Example 1 This comparative example is basically the same as Comparative Example 1, except that the curing agent CA-Pen-IP is replaced with polyamide curing agent (Versamid 140) in this comparative example.

[0100] Comparative Example 2 This comparative example is basically the same as Comparative Example 1, except that the curing agent CA-Pen-IP is replaced with polyamide (CA-ETHA) curing agent in this comparative example.

[0101] Comparative Example 3 This comparative example is basically the same as Comparative Example 1, except that the curing agent CA-Pen-IP is replaced with a modified aminourea curing agent (Ancamide 2396) in this comparative example.

[0102] Test example: The performance of the epoxy molding compounds obtained in the examples and comparative examples was tested, and the test results are shown in Table 2.

[0103] Viscosity Testing: The apparent viscosity of the epoxy molding compound was determined using a Bollerfeld rotational viscometer. The epoxy molding compound sample was placed in a temperature-controlled sample cup. The viscometer was started, and the rotor was rotated at a constant speed within the sample. After the torque reading stabilized, the viscosity value displayed by the instrument was recorded. This stable reading is the apparent viscosity of the sample under the current test conditions.

[0104] Gel time test: The gel time of the epoxy molding compound was determined using a rheometer (Anton Paar, model MCR302) in oscillation mode. At a set constant curing temperature (e.g., 120°C), a constant frequency (e.g., 1 Hz) and a small amplitude oscillating strain (e.g., 1%) were applied, and the viscosity change over time was monitored in real time. The time at which the viscosity reached 100 Pa·s was defined as the gel time.

[0105] Storage stability testing: The storage stability of epoxy molding compound was evaluated using an accelerated aging method. The epoxy molding compound was sealed and placed in a constant temperature environment of 40°C, and its viscosity and gelation time were monitored periodically. The core failure criterion was a relative viscosity increase rate ≥150% (e.g., termination when the initial viscosity rises from 300 Pa·s to 750 Pa·s), supplemented by a gelation time reduction rate ≥30% or a reaction heat consumption rate ≥10% as auxiliary criteria.

[0106] Thermal expansion coefficient test: The test was conducted using a thermomechanical analyzer (TMA, Netzsch Instrument model TMA 402), where the epoxy molding compound sample was heated from room temperature to approximately 300°C at a heating rate of 5°C / min.

[0107] Glass transition temperature test: The glass transition temperature is determined by heating the epoxy molding compound sample from room temperature to about 300°C at a heating rate of 5°C / min using a dynamic thermomechanical analyzer (TMA, Netzsch Instrument model TMA 402). The temperature corresponding to the inflection point on the thermal expansion curve is the glass transition temperature.

[0108] Bending strength test: The bending performance of epoxy molding compound was determined by the three-point bending method, and the method referred to the national standard GBT40564-2021.

[0109] Table 2 Test Results

[0110] Compared with Comparative Examples 1-3, the epoxy molding compounds of Examples 1-10 have better storage stability. It can be seen that the curing agent of this application can enable the epoxy molding compound to have a longer service life.

[0111] Compared to Examples 1-10, the epoxy molding compounds of Examples 1, 2, and 8 have lower curing temperatures. This indicates that Examples 1, 2, and 8, by employing moderately sterically hindered R' groups or a combination of highly sterically hindered R' groups and highly reactive R groups, achieve moderate curing temperatures for the epoxy molding compounds. The epoxy molding compounds of Examples 3, 4, 5, 9, and 10 exhibit better storage stability, higher glass transition temperatures, and lower coefficients of thermal expansion. This demonstrates that the curing agents of Examples 3, 4, 5, 9, and 10, with their highly sterically hindered R' groups, enable the epoxy molding compounds to have longer service life, higher glass transition temperatures, and higher heat distortion temperatures, meeting the stringent heat resistance requirements of high-performance encapsulation.

[0112] In summary, the amine curing agent with amide bonds based on a specific structure provided by this invention achieves the improvement and flexible control of the comprehensive performance of epoxy molding compounds through the precise design of R groups and R' groups, and can effectively broaden the process window without sacrificing the mechanical strength and heat resistance of the material.

[0113] The above provides a detailed description of a curing agent and its preparation method, epoxy molding compound, and epoxy molding compound provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods 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 curing agent, characterized in that, The structural formula of the curing agent is ; wherein R is a linear alkyl group having 2 to 4 carbon atoms, or a hydroxyl group-containing alkyl group having 2 to 4 carbon atoms, or a thioether group-containing alkyl group having 2 to 4 carbon atoms, or ; R' is an alkyl group containing 3-8 carbon atoms and branched, an ether group containing 2-8 carbon atoms and branched, a cycloalkyl group containing 3-6 carbon atoms, or an aryl group containing 6-10 carbon atoms.

2. The curing agent according to claim 1, characterized in that, The R is , , , , or ; The R' is , , , , , , , , or .

3. The curing agent according to claim 2, characterized in that, The R' is or ;or The R is , , or And R' is .

4. The curing agent according to claim 2, characterized in that, The R' is or ;or The R is or And R' is .

5. The curing agent according to claim 2, characterized in that, The R' is , , or ;or The R is or And R' is ;or The R is , , or And R' is .

6. A method for preparing a curing agent, characterized in that, include: A curing agent is obtained by reacting dimethyl dicarboxylate with a chain terminator via an amide condensation reaction. The structural formula of the dimethyl dicarboxylate is as follows: R is a straight-chain alkyl group with 2-4 carbon atoms, or an alkyl group with 2-4 carbon atoms containing a hydroxyl group, or an alkyl group with 2-4 carbon atoms containing a sulfide group. ; The chain terminator has the following structural formula: R' is an alkyl group containing 3-8 carbon atoms and branched, an ether group containing 2-8 carbon atoms and branched, a cycloalkyl group containing 3-6 carbon atoms, or an aryl group containing 6-10 carbon atoms.

7. The method for preparing the curing agent according to claim 6, characterized in that, The dimethyl dicarboxylic acid ester includes , , , , and One or more of the following; The chain terminator includes , , , , , , , , and One or more of them.

8. The method for preparing the curing agent according to claim 7, characterized in that, The chain terminator includes and At least one of them; or The dimethyl dicarboxylic acid ester includes , , and At least one of the following, and the chain terminator includes .

9. The method for preparing the curing agent according to claim 7, characterized in that, The chain terminator includes and At least one of them; or The dimethyl dicarboxylic acid ester includes and At least one of the following, and the chain terminator includes .

10. The method for preparing the curing agent according to claim 7, characterized in that, The chain terminator includes , , and At least one of them; or The dimethyl dicarboxylic acid ester includes and At least one of the following, and the chain terminator includes ;or The dimethyl dicarboxylic acid ester includes , , and At least one of the following, and the chain terminator includes .

11. The method for preparing the curing agent according to claim 7, characterized in that, The molar ratio of the chain terminator to the dimethyl dicarboxylate is greater than or equal to 2.2:1; and / or The temperature of the amide condensation reaction is 60℃-80℃, and the reaction time is 10h-20h.

12. An epoxy molding compound, characterized in that, include: The epoxy resin and the curing agent prepared by the method of any one of claims 1-5 or any one of claims 6-11.

13. The epoxy molding compound according to claim 12, characterized in that, The epoxy resin includes one or more of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, o-cresol epoxy resin, trimethylolpropane triglycidyl ether, and hydrogenated bisphenol A epoxy resin.

14. The epoxy molding compound according to claim 12, characterized in that, It also includes inorganic fillers; The inorganic filler includes at least one of fused silica and crystalline silica; and / or The inorganic filler is an inorganic filler modified with alkoxysilanes having primary amino, secondary amino, tertiary amino, epoxy, mercapto, alkyl, urea, and vinyl groups; and / or The inorganic filler has a particle size of 0.001 μm-100 μm; and / or The inorganic filler has a mass content of 60%-90% in the epoxy molding compound.

15. The epoxy molding compound according to claim 12, characterized in that, It also includes stress absorbers, said stress absorbers comprising at least one of styrene-butadiene copolymers, styrene-butadiene copolymer derivatives, and organosilicon particles; and / or Also includes silane coupling agents; and / or It also includes a release agent, said release agent comprising one or more of linear saturated carboxylic acids, polyethylene wax, carnauba wax, stearic acid, and synthetic paraffin wax; and / or It also includes ion trapping agents, said ion trapping agents comprising one or more of cation trapping agents, anion trapping agents, and anion-cation trapping agents; and / or It also includes fumed silica, wherein the average particle size of the fumed silica is 5 nm to 40 nm.

16. The epoxy molding compound according to claim 15, characterized in that, The molar ratio of epoxy groups in the epoxy resin to amine hydrogen groups in the curing agent is 1:(0.8-1.2); and / or It also includes inorganic fillers, stress absorbers, silane coupling agents, release agents, ion traps and fumed silica, wherein the mass ratio of the epoxy resin, the inorganic fillers, the stress absorbers, the silane coupling agents, the release agents, the ion traps and the fumed silica is (5-15):(75-90):(0.1-5):(0.1-1.5):(0.1-1.5):(0.1-1):(0.5-5).

17. An epoxy molding compound, characterized in that, It is formed by curing the epoxy molding compound as described in any one of claims 12-16.

Images