Anhydride compounds, methods of making the same, combined curing agents, and liquid epoxy encapsulants

Abstract

The application discloses an acid anhydride compound, a preparation method of the acid anhydride compound, a combined curing agent and a liquid epoxy plastic encapsulating material. The structural formula of the acid anhydride compound is as follows: the acid anhydride compound is applied to the liquid epoxy plastic encapsulating material, and unification of high heat resistance, low thermal expansion coefficient and high modulus characteristics can be realized.

Description

Technical Field

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

[0002] In the integrated circuit packaging industry, epoxy molding compounds are key materials for protecting chips and their electronic components. They are typically composed of epoxy resin, inorganic fillers, curing agents, and various additives. In recent years, with the continuous development of packaging technology towards high performance, high integration, and smaller, lighter, and thinner designs, liquid epoxy molding compounds suitable for advanced packaging methods such as wafer-level packaging have emerged. Compared to traditional molding compounds, wafer-level liquid epoxy molding compounds have the following advantages: excellent fluidity, capable of fully filling various microstructures and gaps in the packaging structure; good interfacial bonding capability; a coefficient of thermal expansion matching that of electronic device materials; and excellent heat and moisture resistance, meeting stringent reliability testing requirements. However, in actual R&D, a trade-off between performance is often encountered. For example, balancing heat resistance and toughness, and unifying high filler content with fluidity. Among these challenges, the mismatch in coefficient of thermal expansion caused by high-temperature curing processes, and the warping problem caused by curing shrinkage resulting from the reaction between the resin and the curing agent, have always been difficult to address.

[0003] Current strategies primarily focus on improving the mechanical properties of epoxy molding compounds by increasing the content of inorganic fillers. Silica fillers, especially spherical silica, have a low coefficient of linear expansion; higher filler content results in a lower coefficient of linear expansion, thus reducing thermal stress and warping / delamination during encapsulation. However, excessive filler can lead to excessively high viscosity, increasing workability difficulties. Furthermore, inorganic fillers like silica have poor compatibility with organic resin systems; their small size and large surface area make them prone to aggregation, posing a significant risk to the system's dispersion uniformity. Summary of the Invention

[0004] This application provides an anhydride compound and its preparation method, a combined curing agent, and a liquid epoxy molding compound, aiming to solve the problem of how to simultaneously achieve high heat resistance, high modulus, and low coefficient of thermal expansion in liquid epoxy molding compounds for wafer-level packaging.

[0005] This application provides an acid anhydride compound, the structural formula of which is as follows: .

[0006] Accordingly, this application also provides a method for preparing the aforementioned acid anhydride compound, comprising: The intermediate product was obtained by catalytic reaction of 1-(4-carboxyphenyl)-1,2,2-triphenylene and 4-hydroxyphthalic acid in the presence of an acid catalyst. The structural formula of the intermediate product is as follows: ; The intermediate product is dehydrated under the action of a dehydrating agent to obtain the acid anhydride compound.

[0007] Optionally, in some embodiments of this application, the reaction temperature of the catalytic reaction is 70℃~150℃, and the reaction time is 5h~10h; and / or, The dehydration reaction is carried out at a temperature of 70℃ to 150℃ for a time of 1 hour to 5 hours; and / or, The acid catalyst includes at least one selected from p-toluenesulfonic acid, sulfuric acid, trifluoroacetic acid, and acetic acid; and / or, The dehydrating agent includes at least one of acetic anhydride, dicyclohexylcarbodiimide, trifluoroacetic anhydride, concentrated sulfuric acid, and molecular sieve.

[0008] Accordingly, this application also provides a combined curing agent, comprising a first acid anhydride curing agent and a second acid anhydride curing agent, wherein the mass ratio of the first acid anhydride curing agent to the second acid anhydride curing agent is 1:(5~7), the molecular weight of the second acid anhydride curing agent is less than or equal to 308 g / mol, and the first acid anhydride curing agent is the aforementioned acid anhydride compound or an acid anhydride compound prepared by the aforementioned acid anhydride compound preparation method.

[0009] Optionally, in some embodiments of this application, the molecular weight of the second anhydride curing agent is 166 g / mol to 267 g / mol; and / or, The second anhydride curing agent includes at least one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, and dodecenylsuccinic anhydride.

[0010] In addition, this application also provides a liquid epoxy molding compound, comprising epoxy resin, inorganic filler and the aforementioned combined curing agent; wherein, in the liquid epoxy molding compound, the inorganic filler has a mass percentage of 70wt% to 90wt%.

[0011] Optionally, in some embodiments of this application, the ratio of the epoxy equivalent of the epoxy resin to the anhydride equivalent of the combined curing agent is 1:(0.8~1.2).

[0012] Optionally, in some embodiments of this application, the ratio of the epoxy equivalent of the epoxy resin to the anhydride equivalent of the combined curing agent is 1:(0.9~1.1).

[0013] Optionally, in some embodiments of this application, the epoxy resin is liquid at room temperature; or, the epoxy resin includes monoepoxy compounds and polyepoxy compounds; or, the epoxy resin includes a variety of polyepoxy compounds.

[0014] Optionally, in some embodiments of this application, the mass percentage of epoxy resin in the liquid epoxy molding compound is 0.5wt% to 20wt%.

[0015] Optionally, in some embodiments of this application, the mass percentage of epoxy resin in the liquid epoxy molding compound is 1.0wt% to 15wt%.

[0016] Optionally, in some embodiments of this application, the mass percentage of epoxy resin in the liquid epoxy molding compound is 2.0wt% to 10wt%.

[0017] Optionally, in some embodiments of this application, the inorganic filler includes at least one of silicon dioxide, aluminum oxide, silicon nitride, boron nitride, aluminum nitride, and silicon carbide.

[0018] Optionally, in some embodiments of this application, the inorganic filler includes the silica, which is spherical silica with a particle size range of 1 μm to 55 μm, an average particle size of 1 μm to 15 μm, and a maximum particle size of 10 μm to 55 μm.

[0019] Optionally, in some embodiments of this application, the liquid epoxy molding compound further includes a curing accelerator, wherein the curing accelerator has a mass percentage of 0.1wt% to 5wt%; and / or, The liquid epoxy molding compound further includes a coupling agent, wherein the coupling agent has a mass percentage of 0.1 wt% to 5 wt%; and / or, The liquid epoxy molding compound further includes a stress-relieving agent, wherein the stress-relieving agent has a mass percentage of 0.1wt% to 5wt%; and / or, The liquid epoxy molding compound further includes a diluent, wherein the diluent has a mass percentage of 0.1 wt% to 5 wt%; and / or, The liquid epoxy molding compound further includes a colorant, wherein the colorant has a mass percentage of 0.1 wt% to 1 wt%; and / or, The liquid epoxy molding compound also includes a defoamer, wherein the defoamer has a mass percentage of 0.01wt% to 0.5wt%.

[0020] The acid anhydride compound provided in this application can be used as an epoxy resin curing agent. This acid anhydride compound has a tetraphenylethylene structure. By incorporating the tetraphenylethylene structure into the acid anhydride compound as a molecular backbone, the following advantages can be achieved: (1) The tetraphenylethylene structure has a unique propeller-shaped three-dimensional structure, which can be used as a rigid node in the epoxy resin network, giving the system high rigidity and high heat resistance.

[0021] (2) The non-planar configuration of tetraphenylethylene structure can increase the free volume of epoxy resin polymer network, which is beneficial to improve the local phase separation caused by inorganic filler agglomeration and improve the dispersion uniformity of the system.

[0022] (3) When the epoxy resin system is heated and generates thermal expansion energy, the four phenyl groups of the tetraphenylethylene structure can consume part of the thermal expansion energy by rotating, thereby reducing the thermal expansion coefficient of the epoxy resin system.

[0023] By applying this anhydride compound to liquid epoxy molding compounds, a combination of high heat resistance, low coefficient of thermal expansion, and high modulus properties can be achieved. Attached Figure Description

[0024] Figure 1 This is a synthetic route diagram of the acid anhydride compound in Preparation Example 1 of this application; Figure 2 This is the NMR spectrum of the intermediate product in Preparation Example 1 of this application; Figure 3 This is the NMR spectrum of the acid anhydride compound prepared in Example 1 of this application. Detailed Implementation

[0025] 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.

[0026] This application provides an anhydride compound and its preparation method, a combined curing agent, and a liquid epoxy molding compound. 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 a range format; it should be understood that the description in a range format 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.

[0027] Currently, there is a lack of liquid epoxy molding compounds that can simultaneously achieve high heat resistance, high modulus, low coefficient of thermal expansion, and good process flowability. In existing wafer-level packaging liquid epoxy molding compounds, the coefficient of thermal expansion (CTE) is mismatched with that of silicon chips, substrates, and other materials, leading to thermal stress during cooling after high-temperature curing. Increasing the content of inorganic fillers (≥70%) in liquid epoxy molding compounds can reduce the CTE; however, excessively high filler content results in a sharp increase in viscosity, decreased flowability, reduced workability, and difficulty in filling microstructures. Using high-heat-resistant (high Tg) curing agents leads to high crosslinking density and rigidity, resulting in high modulus after curing but poor toughness, increased internal stress, and a tendency to crack.

[0028] In this regard, this application provides an acid anhydride compound with the following structural formula: .

[0029] The acid anhydride compound provided in this application embodiment can be used as an epoxy resin curing agent. This acid anhydride compound has a tetraphenylethylene (TPE) structure and an acid anhydride group (-CO-O-CO-). By introducing the tetraphenylethylene structure into the acid anhydride compound as a molecular backbone, the following advantages can be obtained: (1) The tetraphenylethylene structure has a unique propeller-shaped three-dimensional structure, which can be used as a rigid node in the epoxy resin network, giving the system high rigidity and high heat resistance.

[0030] (2) The non-planar configuration of tetraphenylethylene structure can increase the free volume of epoxy resin polymer network, which is beneficial to improve the local phase separation caused by inorganic filler agglomeration and improve the dispersion uniformity of the system.

[0031] (3) When the epoxy resin system is heated and generates thermal expansion energy, the four phenyl groups of the tetraphenylethylene structure can consume part of the thermal expansion energy by rotating, thereby reducing the thermal expansion coefficient of the epoxy resin system.

[0032] By applying this anhydride compound to liquid epoxy molding compounds, a combination of high heat resistance, low coefficient of thermal expansion, and high modulus properties can be achieved.

[0033] This application also provides a method for preparing the aforementioned acid anhydride compound, including: S10. 1-(4-Carboxyphenyl)-1,2,2-tristyrene and 4-hydroxyphthalic acid were reacted under the action of an acid catalyst to obtain an intermediate product. The structural formula of the intermediate product is as follows: ; S20. The intermediate product is dehydrated under the action of a dehydrating agent to obtain an acid anhydride compound.

[0034] In some embodiments of this application, step S10 specifically includes S101 to S105: S101. 1-(4-Carboxyphenyl)-1,2,2-triphenylene is provided. The structural formula of 1-(4-Carboxyphenyl)-1,2,2-triphenylene is shown below: .

[0035] S102, provides 4-hydroxyphthalic acid. The structural formula of 4-hydroxyphthalic acid is shown below: .

[0036] S103. Dissolve 1-(4-carboxyphenyl)-1,2,2-triphenylene in the first organic solvent, add 4-hydroxyphthalic acid and mix well to obtain the first mixture. S104. An acid catalyst is gradually added dropwise to the first mixture. The acid catalyst catalyzes the reaction between 1-(4-carboxyphenyl)-1,2,2-tristyrene and 4-hydroxyphthalic acid. S105. Remove the first organic solvent by vacuum distillation, wash, extract, and dry to obtain the intermediate product.

[0037] In S103, the first organic solvent includes at least one of anhydrous N,N-dimethylformamide (DMF), anhydrous tetrahydrofuran (THF), anhydrous 1,4-dioxane, and anhydrous toluene.

[0038] In S104, the acid catalyst includes at least one selected from p-toluenesulfonic acid, sulfuric acid, trifluoroacetic acid, and acetic acid. The reaction temperature of the catalytic reaction is 70℃~150℃, and the reaction time is 5h~10h. As an example, the reaction temperature of the catalytic reaction is 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, or 150℃; and the reaction time is 5h, 6h, 7h, 8h, 9h, or 10h.

[0039] In some embodiments of this application, step S20 specifically includes S201~S202: S201. Dissolve the intermediate product thoroughly in the second organic solvent to obtain the second mixture; S202. A dehydrating agent is gradually added dropwise to the second mixture, and the intermediate product undergoes a dehydration reaction to obtain an acid anhydride compound.

[0040] In S201, the second organic solvent includes at least one of anhydrous ethyl acetate, anhydrous toluene, anhydrous dichloromethane, and anhydrous diethyl ether.

[0041] In S202, the dehydrating agent includes at least one of acetic anhydride, dicyclohexylcarbodiimide (DCC), trifluoroacetic anhydride (TFAA), concentrated sulfuric acid, and molecular sieve. The dehydration reaction temperature is 70℃~150℃, and the reaction time is 1h~5h. As an example, the dehydration reaction temperature is 70℃, 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, or 150℃; and the reaction time is 1h, 2h, 3h, 4h, or 5h.

[0042] This application also provides a combined curing agent, including a first acid anhydride curing agent and a second acid anhydride curing agent, wherein the mass ratio of the first acid anhydride curing agent and the second acid anhydride curing agent is 1:(5~7), the molecular weight of the second acid anhydride curing agent is less than or equal to 308 g / mol, and the first acid anhydride curing agent is the aforementioned acid anhydride compound or an acid anhydride compound prepared by the aforementioned acid anhydride compound preparation method.

[0043] The combined curing agent provided in this application includes two anhydride-based curing agents. Specifically, the combined curing agent includes a first anhydride curing agent and a second anhydride curing agent. The first anhydride curing agent is the aforementioned anhydride compound or an anhydride compound prepared by the aforementioned method. The second anhydride curing agent is a low molecular weight anhydride curing agent, wherein the molecular weight of the second anhydride curing agent is less than or equal to 308 g / mol. The molecule of the second anhydride curing agent can contain one or more anhydride groups. Optionally, at room temperature, the second anhydride curing agent is liquid or soluble in epoxy resin.

[0044] Anhydride equivalent refers to the ratio of the molecular weight of anhydride to the number of anhydride groups. Typically, the first anhydride curing agent has a relatively high anhydride equivalent. Therefore, a low-molecular-weight second anhydride curing agent is selected and combined with the first anhydride curing agent to form a combined curing agent, thereby reducing the overall anhydride equivalent of the combined curing agent. In this way, high-density crosslinking of epoxy resin can be achieved using a small amount of the combined curing agent.

[0045] As an example, the molecular weight of the second anhydride curing agent is any one or a range between any two of the following: 60 g / mol, 80 g / mol, 100 g / mol, 120 g / mol, 140 g / mol, 160 g / mol, 180 g / mol, 200 g / mol, 220 g / mol, 240 g / mol, 260 g / mol, 280 g / mol, 300 g / mol, and 308 g / mol.

[0046] In addition, the low molecular weight second anhydride curing agent can also contribute to low viscosity and improve the process flowability of liquid epoxy molding compounds. Specifically, in the combined curing agent, the mass ratio of the first anhydride curing agent and the second anhydride curing agent is 1:(5~7). When the combined curing agent is applied to liquid epoxy molding compounds, the use of the first anhydride curing agent can bring high heat resistance, low coefficient of thermal expansion, and high modulus to the cured liquid epoxy molding compound. When the mass ratio of the first anhydride curing agent and the second anhydride curing agent is less than 1:7, that is, the content of the first anhydride curing agent decreases and the content of the second anhydride curing agent increases, this will lead to a decrease in the heat resistance and mechanical strength of the cured liquid epoxy molding compound. However, if the mass ratio of the first anhydride curing agent and the second anhydride curing agent is greater than 1:5, that is, the content of the first anhydride curing agent increases and the content of the second anhydride curing agent decreases, the viscosity of the liquid epoxy molding compound will increase, the process flowability will deteriorate, and it may also affect the curing effect of the epoxy resin.

[0047] As an example, in the combined curing agent, the mass ratio of the first acid anhydride curing agent and the second acid anhydride curing agent is 1:5, 1:5.5, 1:6, 1:6.5 or 1:7.

[0048] Each type of acid anhydride curing agent exhibits different effects in liquid epoxy molding compounds, and the addition of different types of acid anhydride curing agents also has varying impacts on the relevant properties of liquid epoxy molding compounds, such as storage modulus, glass transition temperature (Tg), and coefficient of thermal expansion (CTE). While different acid anhydride curing agents may improve one aspect of performance, they may also reduce other properties of the liquid epoxy molding compound.

[0049] In this embodiment, a combined curing agent is formed by mixing an anhydride compound with a tetraphenylethylene structure with a low molecular weight anhydride curing agent with a molecular weight less than or equal to 308 g / mol. The mass ratio of the two types of curing agents is controlled to be 1:(5~7). When this combined curing agent is applied to liquid epoxy molding compound, while ensuring good curing effect of liquid epoxy molding compound, it achieves a balance of high heat resistance, low coefficient of thermal expansion, high modulus and good process flowability.

[0050] In some embodiments of this application, the second anhydride curing agent includes at least one selected from methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, and dodecenylsuccinic anhydride. The molecular weight of methyltetrahydrophthalic anhydride is 166.17 g / mol, the molecular weight of methylhexahydrophthalic anhydride is 168.19 g / mol, the molecular weight of methylnadic anhydride is 178.18 g / mol, and the molecular weight of dodecenylsuccinic anhydride is 266.38 g / mol. Optionally, the molecular weight of the second anhydride curing agent is between 166 g / mol and 267 g / mol.

[0051] In some embodiments of this application, the mass percentage of anhydride groups (-CO-C-CO-) in the combined curing agent is 21.8 wt% to 54.2 wt%. Within this range, the combined curing agent can be used to achieve good cross-linking and curing effects in liquid epoxy molding compounds. Optionally, the mass percentage of anhydride groups (-CO-C-CO-) in the combined curing agent is 24.9 wt% to 39.7 wt%.

[0052] As an example, the mass percentage of anhydride groups (-CO-C-CO-) in the combined curing agent is any one or any two of the following: 21.8wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, and 54.2wt%.

[0053] This application embodiment also provides a liquid epoxy molding compound, including epoxy resin, inorganic filler and the aforementioned combined curing agent; wherein, in the liquid epoxy molding compound, the mass percentage of inorganic filler is 70wt%~90wt%.

[0054] In liquid epoxy molding compounds, the mass percentage of inorganic filler is 70wt% to 90wt%. When the mass percentage of inorganic filler is below the lower limit of 70wt%, the coefficient of thermal expansion of the liquid epoxy molding compound is relatively large, resulting in excessive warpage after encapsulation; when the mass percentage of inorganic filler is above the upper limit of 90wt%, the viscosity of the liquid epoxy molding compound is too high, reducing workability. As an example, the mass percentage of inorganic filler in the liquid epoxy molding compound is 70wt%, 75wt%, 80wt%, 85wt%, or 90wt%. Optionally, the inorganic filler includes at least one of silica, alumina, silicon nitride, boron nitride, aluminum nitride, and silicon carbide.

[0055] The acid anhydride compounds containing the TPE molecular skeleton in the combined curing agent have the potential to enhance the rigidity, heat resistance, and hydrophobicity of the liquid epoxy molding compound system after curing by utilizing their structural characteristics. With 70wt%~90wt% inorganic filler, the low viscosity of the combined acid anhydride curing agent system allows the liquid epoxy molding compound to maintain good process fluidity, uniform dispersion of inorganic fillers, and low coefficient of thermal expansion, achieving a performance balance under high filler content.

[0056] In summary, the liquid epoxy molding compound provided in this application, through the combination of high-filled inorganic fillers and a combination of curing agents, can simultaneously improve heat resistance, modulus, and low coefficient of thermal expansion without sacrificing process flowability. This liquid epoxy molding compound can be used for wafer-level packaging and possesses characteristics of high temperature resistance, low warpage, and high modulus.

[0057] In some embodiments of this application, the ratio of epoxy equivalent of the epoxy resin to anhydride equivalent of the combined curing agent is 1:(0.8~1.2). Epoxy equivalent is the ratio of the molecular weight of the epoxy resin to the number of epoxy groups; anhydride equivalent is the ratio of the molecular weight of the anhydride to the number of anhydride groups. If the anhydride equivalent in the liquid epoxy molding compound is less than 0.8, the crosslinking density of the liquid epoxy molding compound decreases, easily leading to a decrease in heat resistance; if the anhydride equivalent exceeds 1.2, excessive anhydride residue is likely to exist, leading to a decrease in moisture resistance. Optionally, the ratio of epoxy equivalent to anhydride equivalent is 1:(0.9~1.1).

[0058] As an example, the ratio of the epoxy equivalent of the epoxy resin to the anhydride equivalent of the combined curing agent is 1:0.8, 1:0.9, 1:1.0, 1:1.1, or 1:1.2.

[0059] In some embodiments of this application, the epoxy resin is in a liquid state at room temperature.

[0060] In some embodiments of this application, the epoxy resin includes monoepoxy compounds and polyepoxy compounds; or, the epoxy resin includes a variety of polyepoxy compounds. Through the synergy of multi-component epoxy resins and multi-component anhydride systems, such as a combination of bisphenol A type epoxy resin and alicyclic epoxy resin, a cross-linked network structure is formed, further improving the balance between heat resistance and mechanical modulus.

[0061] Optionally, the polyepoxy compound is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, cresol phenolic varnish, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, aminophenol type epoxy resin, polyether type epoxy resin, alcohol ether type epoxy resin, alicyclic epoxy resin, and aliphatic epoxy resin. The alicyclic epoxy resin is selected from one or more combinations of 1,2-epoxy-4-vinylcyclohexane, 3,4-epoxycyclohexylmethyl methacrylate, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylmethyl ester, bis(7-oxabicyclo[4.1.0]3-heptylmethyl) adipate, methyl 3,4-epoxycyclohexanecarboxylate, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester, and 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexanecarboxylic acid).

[0062] In some embodiments of this application, the epoxy resin in the liquid epoxy molding compound comprises 0.5 wt% to 20 wt% by mass. As examples, the epoxy resin by mass percentage is 0.5 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, or 20 wt%. Optionally, the epoxy resin by mass percentage is 1.0 wt% to 15 wt%. Optionally, the epoxy resin by mass percentage is 2.0 wt% to 10 wt%.

[0063] In some embodiments of this application, the inorganic filler includes silica, specifically spherical silica. Spherical silica is easily dispersed, does not easily agglomerate, and has a uniform particle distribution. The particle size range of the spherical silica is 1 μm to 55 μm, the average particle size is 1 μm to 15 μm, and the maximum particle size is 10 μm to 55 μm.

[0064] In some embodiments of this application, the liquid epoxy molding compound further includes a curing accelerator. The curing accelerator accelerates the curing reaction of the epoxy resin. The curing accelerator is present in the liquid epoxy molding compound at a mass percentage of 0.1 wt% to 5 wt%. As an example, the mass percentage of the curing accelerator is any one or a range between any two of 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%.

[0065] Optionally, the curing accelerator is selected from one or more of amine curing accelerators, imidazole curing accelerators, phosphorus curing accelerators, phosphonium salt curing accelerators, bicyclic amidines and their derivatives, organometallic complexes, and urea compounds of polyamines. Among these, amine curing accelerators may be selected from dicyandiamide, modified amine compounds, and amine adduct compounds, etc. Imidazole curing accelerators may be selected from one or more of 2-ethyl-4-methylimidazolium, 2,3-dihydro-1H-pyrrole[1,2-a]benzimidazole, 1-cyanoethyl-2-methylimidazolium, 1-cyanoethyl-2-imidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, 1-cyanoethyl-2-methylimidazolium trimellitate, 1-cyanoethyl-2-ethyl-4-methylimidazolium trimellitate, 2-methylimidazolium-triisocyanate, 2-4-methyl-5-hydroxymethylimidazolium, and 2-4-benzyl-5-hydroxymethylimidazolium. The organophosphorus curing accelerator is selected from one or more of triphenylphosphine and 1,4-p-benzoquinone adducts or triphenylphosphine.

[0066] In some embodiments of this application, the liquid epoxy molding compound further includes a coupling agent, wherein the mass percentage of the coupling agent is 0.1 wt% to 5 wt%. As an example, the mass percentage of the coupling agent is any one or a range between any two of 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%.

[0067] In some embodiments, the coupling agent is selected from alkoxysilane compounds. Alkoxysilane compounds include one or more of the following: alkoxysilane compounds having a primary amino group, alkoxysilane compounds having a secondary amino group, alkoxysilane compounds having a tertiary amino group, alkoxysilane compounds having an epoxy group, alkoxysilane compounds having a mercapto group, alkoxysilane compounds having an alkyl group, alkoxysilane compounds having a urea group, and alkoxysilane compounds having a vinyl group. Further, the coupling agent is selected from alkoxysilane compounds having an epoxy group. Alkoxysilane compounds having an epoxy group are selected from 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, vinyltrimethoxysilane, etc.

[0068] In some embodiments of this application, the liquid epoxy molding compound further includes a stress-relieving agent, wherein the stress-relieving agent has a mass percentage of 0.1 wt% to 5 wt%. As an example, the mass percentage of the stress-relieving agent is any one or a range between any two of 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%.

[0069] Optionally, the stress-relieving agent is selected from any one or a combination of at least two of the following: epoxy-modified silicone oil with a polysiloxane structure, liquid silicone rubber, organosilicon-modified epoxy resin, polyether elastomer, polyurethane, styrene-butadiene copolymer and its derivatives. Further, the stress-relieving agent is selected from any one or a combination of at least two of the following: acrylonitrile-butadiene-styrene copolymer, epoxy-terminated styrene-butadiene-styrene block copolymer, epoxidized styrene-butadiene-styrene block copolymer, styrene-butadiene rubber, carboxyl-terminated liquid nitrile butadiene rubber (CTBN), and hydroxyl-terminated liquid nitrile butadiene rubber (HTBN).

[0070] In some embodiments of this application, the liquid epoxy molding compound further includes a diluent, wherein the mass percentage of the diluent is 0.1 wt% to 5 wt%. As an example, the mass percentage of the diluent is any one or a range between any two of 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%.

[0071] Optionally, the diluent is selected from any one or a combination of at least two of the following: polypropylene glycol diglycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, tolyl glycidyl ether, p-sec-butylphenyl glycidyl ether, allyl glycidyl ether, glycidyl methacrylate, glycidyl acrylate, 1-vinyl-3,4-epoxycyclohexane, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, and glycerol triglycidyl ether.

[0072] In some embodiments of this application, the liquid epoxy molding compound further includes a colorant, wherein the colorant has a mass percentage of 0.1 wt% to 1 wt%. As an example, the mass percentage of the colorant is any one or a range between any two of 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, and 1 wt%. In one example, the colorant is carbon black.

[0073] In some embodiments of this application, the liquid epoxy molding compound further includes a defoamer, wherein the defoamer has a mass percentage of 0.01 wt% to 0.5 wt%. As an example, the defoamer mass percentage is any one or a range between any two of 0.01 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, and 0.5 wt%. In one example, the defoamer is an acrylic copolymer.

[0074] In some embodiments of this application, the liquid epoxy molding compound includes epoxy resin, curing agent, inorganic filler, curing accelerator, coupling agent, stress release agent, diluent, colorant, and defoamer. The preparation method of the liquid epoxy molding compound includes: The epoxy resin, stress-relieving agent, coupling agent, diluent, colorant and defoamer are stirred and mixed to obtain a mixture; wherein the stirring speed is 800 rpm to 1800 rpm and the stirring time is 1 min to 8 min.

[0075] The curing agent and inorganic filler were added to the mixture in three batches. After each addition of the curing agent and inorganic filler, the mixture was stirred at a speed of 800 rpm to 1800 rpm for 1 min to 6 min. Then the curing accelerator was added and stirred at a speed of 1000 rpm to 2000 rpm for 1 min to 5 min to obtain liquid epoxy molding compound.

[0076] The following description is based on specific embodiments.

[0077] Preparation Example 1 This preparation example provides an acid anhydride compound; please refer to [link to preparation example]. Figure 1 The preparation process of this anhydride compound includes: S11. In a 100 mL dry round-bottom flask, weigh 1.0 mmol (approximately 0.38 g) of 1-(4-carboxyphenyl)-1,2,2-tristyrene (CAS: 197153-87-0). Add 15 mL of anhydrous 1,4-dioxane and stir magnetically until completely dissolved. Weigh 1.2 mmol (approximately 0.22 g) of 4-hydroxyphthalic acid (CAS: 610-35-5) and add it to the flask. Continue stirring for 10 minutes until the system is homogeneous, obtaining the first mixture. Subsequently, dissolve 0.1 mmol (approximately 19 mg) of p-toluenesulfonic acid (PTSA) in 1 mL of 1,4-dioxane to obtain the catalyst solution. Using a constant-pressure dropping funnel, slowly add the catalyst solution dropwise at room temperature with stirring (approximately 5 minutes). After the addition is complete, raise the temperature to 80 °C. React for 8 hours, taking samples every 2 hours for TLC monitoring.

[0078] S12. Remove the first organic solvent by vacuum distillation, wash, extract, and dry to obtain the intermediate product; S13. Add the intermediate product obtained in the previous step (approximately 1.0 mmol) to a dry round-bottom flask. Add 15 mL of anhydrous ethyl acetate and stir magnetically until completely dissolved. If a small amount of insoluble matter remains, filter it off to obtain a second mixture. While stirring, slowly add 2.0 mmol (approximately 0.19 mL) of acetic anhydride dropwise through a constant-pressure dropping funnel (dropping time approximately 5 minutes). After the addition is complete, raise the temperature to 75°C. React for 5 hours, monitoring the reaction progress with TLC. The target product is obtained, denoted as anhydride compound A.

[0079] The intermediate products and target products in the preparation process were characterized by nuclear magnetic resonance (NMR). The obtained NMR spectra can be found in [reference 1]. Figure 2 and Figure 3 .

[0080] Example 1 This embodiment provides a liquid epoxy molding compound, and the preparation method of the liquid epoxy molding compound is as follows: S21. Produce the liquid epoxy molding compound according to the design formula. Please refer to Table 1 for the design formula of the liquid epoxy molding compound: Table 1

[0081] In the designed liquid epoxy molding compound, the total content of epoxy resin is 7.8 wt%, which includes liquid epoxy resin 1 and liquid epoxy resin 2, with a mass ratio of 5:2.8. The total content of curing agent is 5.35 wt%, which includes curing agent 1 and curing agent 2, with a mass ratio of 1:6. Curing agent 2 is methylhexahydrophthalic anhydride.

[0082] S22. Stir the epoxy resin, stress relief agent, coupling agent, diluent, colorant, and defoamer at 1500 rpm for 5 minutes until they are evenly mixed to obtain a mixture. S23. Add the curing agent and inorganic filler to the above mixture in three batches, stirring at 1500 rpm for 5 minutes each time the curing agent and inorganic filler are added; finally, add the curing accelerator to the above mixture and stir at 1800 rpm for 3 minutes to obtain the liquid epoxy molding compound for wafer-level packaging.

[0083] All mixing operations were performed at room temperature.

[0084] Example 2 This embodiment provides a liquid epoxy molding compound. The preparation method of this liquid epoxy molding compound is described in Example 1, except that the mass ratio of curing agent 1 to curing agent 2 is adjusted to 1:5.

[0085] Example 3 This embodiment provides a liquid epoxy molding compound. The preparation method of this liquid epoxy molding compound is described in Example 1, except that the mass ratio of curing agent 1 to curing agent 2 is adjusted to 1:7.

[0086] Example 4 This embodiment provides a liquid epoxy molding compound. The preparation method of this liquid epoxy molding compound can be found in Example 1, except that methyltetrahydrophthalic anhydride is used instead of methylhexahydrophthalic anhydride.

[0087] Example 5 This embodiment provides a liquid epoxy molding compound. The preparation method of this liquid epoxy molding compound can be found in Example 1, except that dodecenyl succinic anhydride is used instead of methyl hexahydrophthalic anhydride.

[0088] Example 6 This embodiment provides a liquid epoxy molding compound. The preparation method of the liquid epoxy molding compound can be found in Example 1. The difference is that the total content of epoxy resin in the designed liquid epoxy molding compound is 16.7 wt%, the total content of curing agent is 11.45 wt%, and the total content of inorganic filler is 70 wt%.

[0089] Example 7 This embodiment provides a liquid epoxy molding compound. The preparation method of the liquid epoxy molding compound can be found in Example 1. The difference is that the total content of epoxy resin in the designed liquid epoxy molding compound is 4.83wt%, the total content of curing agent is 3.32wt%, and the total content of inorganic filler is 90wt%.

[0090] Comparative Example 1 This embodiment provides a liquid epoxy molding compound. The preparation method of the liquid epoxy molding compound can be found in Example 1, except that the curing agent only includes curing agent 2, which is methylhexahydrophthalic anhydride.

[0091] Comparative Example 2 This embodiment provides a liquid epoxy molding compound. The preparation method of the liquid epoxy molding compound is described in Example 1, except that the curing agent only includes curing agent 1, which is an acid anhydride compound A.

[0092] Please refer to Tables 2 and 3 for the design formulations of liquid epoxy molding compounds for each embodiment and comparative example.

[0093] Table 2

[0094] Table 3

[0095] The following performance tests were performed on the liquid epoxy molding compounds prepared in each embodiment and comparative example: 1. Coefficient of Thermal Expansion Test: The cured product of liquid epoxy molding compound with dimensions of 3mm × 3mm × 5mm was measured using a TMA402 thermomechanical analyzer. Measurements were taken at a heating rate of 5℃ / min from 0℃ to 260℃. The coefficient of thermal expansion (ppm / ℃) below the Tg point is designated as CTE1, and the coefficient of thermal expansion (ppm / ℃) above the Tg point is designated as CTE2.

[0096] 2. Energy storage modulus test: The test was conducted using a dynamic mechanical analyzer (DMA, model Q80) under a 1Hz sinusoidal strain load in a double cantilever mode.

[0097] 3. Glass transition temperature (Tg) test: The cured product of liquid epoxy molding compound with dimensions of 12mm × 60mm × 3mm was measured using a DMA830 dynamic mechanical analyzer. A double cantilever mode was used, with an amplitude of 10μm and a frequency of 1.0Hz, and measurements were taken from 0℃ to 260℃ at a heating rate of 5℃ / min.

[0098] 4. Viscosity test: The viscosity of the freshly prepared evaluation sample was measured using a rotational rheometer MCR302 at a liquid temperature of 25℃ and a rotational speed of 25 rpm.

[0099] The test results are recorded in Tables 4 and 5.

[0100] Table 4

[0101] Table 5

[0102] Results analysis: 1. The acid anhydride compound A with a TPE structure provided in this application has a significant effect on improving the heat resistance (Tg) of the cured liquid epoxy molding compound (hereinafter referred to as the cured product).

[0103] Comparing the data in Table 4 for Comparative Example 1 (a single anhydride curing agent) and Examples 1-3 (combined curing agents obtained by compounding), it can be seen that the combined curing agent introducing anhydride compound A can significantly increase the glass transition temperature (Tg) of the cured product. In Comparative Example 1, when using a single anhydride curing agent, methylhexahydrophthalic anhydride, the Tg of the cured product was 154℃; while in Example 1, when anhydride compound A was introduced to form a compound system, the Tg of the cured product jumped to 172℃, an increase of 18℃. This result indicates that the rigid framework of the TPE structure effectively restricts the movement of molecular chain segments, significantly improving the heat resistance of the crosslinked network. In Comparative Example 2, only anhydride compound A was used, but the liquid epoxy molding compound sample failed to cure. A possible reason is that the molecular weight of anhydride compound A with a TPE structure is relatively large, and the anhydride equivalent provided under the same mass percentage conditions is insufficient, leading to curing failure of the system.

[0104] 2. The acid anhydride compound A with a TPE structure has an enhancing effect on the storage modulus of the cured liquid epoxy molding compound.

[0105] The data in Table 4 show that the combined curing agent improves the heat resistance of the cured material without sacrificing its rigidity; on the contrary, it further increases the storage modulus of the cured material.

[0106] Regarding the low-temperature modulus (25°C): In Comparative Example 1, when a single anhydride curing agent, methylhexahydrophthalic anhydride, was used, the storage modulus was 15.1 GPa; in Example 1, when a compound of methylhexahydrophthalic anhydride and anhydride compound A was used, the storage modulus was increased to 16.8 GPa.

[0107] Regarding the high-temperature modulus (260°C): at temperatures far above Tg, the modulus of the compound system (Example 1) (1.08 GPa) is still superior to that of the single system (Comparative Example 1) (0.99 GPa). This indicates that the introduction of anhydride compound A with a TPE structure not only improves the mechanical strength of the cured product at room temperature but also enhances its dimensional stability at high temperatures, which is crucial for wafer-level packaging to withstand high-temperature reflow soldering processes.

[0108] 3. Optimization window for compounding ratio: Comparing Examples 1, 2, and 3, it can be seen that the mixing ratio of methylhexahydrophthalic anhydride to anhydride compound A has a regulating effect on the properties of the cured product. Example 1 (6:1 ratio) exhibited the best Tg (172°C) and modulus balance; Example 2 (5:1 ratio, with increased content of anhydride compound A having a TPE structure) had the highest modulus (17.5 GPa), but the viscosity of the liquid epoxy molding compound increased significantly; Example 3 (7:1 ratio, with increased content of methylhexahydrophthalic anhydride) had a lower coefficient of thermal expansion, but the Tg also decreased slightly. Therefore, when the mass ratio of methylhexahydrophthalic anhydride to anhydride compound A is around 6:1, the best synergistic effect of heat resistance and mechanical strength can be achieved.

[0109] 4. Trade-offs regarding the coefficient of thermal expansion: Although the combined curing agent significantly improved the Tg and modulus of the cured product, its coefficient of thermal expansion (CTE1) was slightly higher than that of the single anhydride system (7.08 ppm / ℃ in Example 1 vs. 6.34 ppm / ℃ in Comparative Example 1). This is likely because the introduction of the TPE structure increases the free volume of the polymer network at room temperature. Despite the slight increase in CTE1, CTE2 decreased significantly, indicating that the rigid framework of TPE can effectively suppress the thermal expansion of the system under high-temperature conditions. Furthermore, considering the substantial increase in Tg (from 154℃ to 172℃) and the increase in storage modulus, this slight change in CTE is acceptable, and the overall CTE is still controlled at a low level (<8 ppm / ℃) by using a high content of spherical silica filler (85%), meeting the requirements for wafer-level packaging to resist warpage.

[0110] 5. Verification of the balance between viscosity characteristics and high-filling process: Viscosity data further revealed key characteristics of the compound system in terms of process adaptability. Test results showed that the viscosity (25°C) of the compound system was generally higher than that of the single anhydride system. For example, the viscosity of Comparative Example 1 (single methylhexahydrophthalic anhydride) was 416 Pa·s, while the viscosity of Example 1 (a compound of methylhexahydrophthalic anhydride and anhydride compound A) increased to 443 Pa·s, and the viscosity of Example 2 (highest modulus) reached 471 Pa·s. This increase in viscosity is mainly attributed to the high molecular rigidity and intermolecular forces of the anhydride compound A with the TPE structure provided in this application. However, the viscosity of compound examples 1-3 was controlled below 500 Pa·s, and the system successfully achieved an ultra-high inorganic filler loading of 85%. This indicates that this technical solution effectively offsets the thickening effect of the rigid anhydride (anhydride compound A provided in this application) through the 'dilution' effect of the low molecular weight anhydride (methylhexahydrophthalic anhydride), maintaining excellent process flowability under the premise of high filling and high modulus.

[0111] The difference between Example 4 and Example 1 is that methyltetrahydrophthalic anhydride was used instead of methylhexahydrophthalic anhydride. Methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride have similar molecular weights, and the results showed that Example 4 and Example 1 had similar coefficients of thermal expansion, storage modulus, glass transition temperature, and viscosity. The difference between Example 5 and Example 1 is that dodecenylsuccinic anhydride was used instead of methylhexahydrophthalic anhydride. Dodecenylsuccinic anhydride has a larger molecular weight than methylhexahydrophthalic anhydride, and the results showed that Example 5, compared to Example 1, had a higher coefficient of thermal expansion and viscosity, and a lower storage modulus and glass transition temperature. It can be seen that reducing the molecular weight of curing agent 2 (i.e., the second anhydride curing agent) is beneficial to improving the overall performance of the liquid epoxy molding compound.

[0112] The difference between Example 6 and Example 1 is that the total content of inorganic filler was reduced to 70 wt%, and correspondingly, the total content of epoxy resin and curing agent was increased. The results showed that, compared to Example 1, Example 6 had a higher coefficient of thermal expansion, storage modulus, and glass transition temperature (Tg, DMA), but a lower viscosity. The difference between Example 7 and Example 1 is that the total content of inorganic filler was increased to 90 wt%, and correspondingly, the total content of epoxy resin and curing agent was reduced. The results showed that, compared to Example 1, Example 7 had a lower coefficient of thermal expansion, storage modulus, and glass transition temperature (Tg, DMA), but a higher viscosity. This indicates that changes in the content of inorganic filler in liquid epoxy molding compounds significantly affect the performance of the liquid epoxy molding compound and its cured product. Adjusting the proportions of each component in the liquid epoxy molding compound helps to achieve a balance between "high heat resistance," "high modulus," "low coefficient of thermal expansion," and "good processability."

[0113] In summary, the acid anhydride compound with a TPE molecular backbone structure provided in this application, combined with a multi-component epoxy resin and highly filled inorganic filler, successfully solves the technical problem that traditional acid anhydride systems struggle to achieve "high heat resistance", "high modulus", "low coefficient of thermal expansion" and "good processability" in an overall formulation design.

[0114] The foregoing has provided a detailed description of an anhydride compound, its preparation method, combined curing agent, and liquid 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. An acid anhydride compound, characterized in that, The structural formula of the acid anhydride compound is as follows: 。 2. The method for preparing the acid anhydride compound according to claim 1, characterized in that, include: The intermediate product was obtained by catalytic reaction of 1-(4-carboxyphenyl)-1,2,2-triphenylene and 4-hydroxyphthalic acid in the presence of an acid catalyst. The structural formula of the intermediate product is as follows: ; The intermediate product is dehydrated under the action of a dehydrating agent to obtain the acid anhydride compound.

3. The method for preparing the acid anhydride compound according to claim 2, characterized in that, The catalytic reaction is carried out at a temperature of 70℃ to 150℃ for a reaction time of 5h to 10h; and / or, The dehydration reaction is carried out at a temperature of 70℃ to 150℃ for a time of 1 hour to 5 hours; and / or, The acid catalyst includes at least one selected from p-toluenesulfonic acid, sulfuric acid, trifluoroacetic acid, and acetic acid; and / or, The dehydrating agent includes at least one of acetic anhydride, dicyclohexylcarbodiimide, trifluoroacetic anhydride, concentrated sulfuric acid, and molecular sieve.

4. A composite curing agent, characterized in that, It includes a first acid anhydride curing agent and a second acid anhydride curing agent, wherein the mass ratio of the first acid anhydride curing agent to the second acid anhydride curing agent is 1:(5~7), the molecular weight of the second acid anhydride curing agent is less than or equal to 308 g / mol, and the first acid anhydride curing agent is the acid anhydride compound according to claim 1 or the acid anhydride compound prepared by the preparation method of the acid anhydride compound according to claim 2 or 3.

5. The combined curing agent according to claim 4, characterized in that, The molecular weight of the second anhydride curing agent is 166 g / mol to 267 g / mol; and / or, The second anhydride curing agent includes at least one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, and dodecenylsuccinic anhydride.

6. A liquid epoxy molding compound, characterized in that, It includes epoxy resin, inorganic filler and the combined curing agent as described in claim 4 or 5; wherein, in the liquid epoxy molding compound, the inorganic filler has a mass percentage of 70wt% to 90wt%.

7. The liquid epoxy molding compound according to claim 6, characterized in that, The ratio of the epoxy equivalent of the epoxy resin to the anhydride equivalent of the combined curing agent is 1:(0.8~1.2); or, the ratio of the epoxy equivalent of the epoxy resin to the anhydride equivalent of the combined curing agent is 1:(0.9~1.1).

8. The liquid epoxy molding compound according to claim 6, characterized in that, The epoxy resin is liquid at room temperature; or, the epoxy resin includes monoepoxy compounds and polyepoxy compounds; or, the epoxy resin includes a variety of polyepoxy compounds.

9. The liquid epoxy molding compound according to claim 6, characterized in that, In the liquid epoxy molding compound, the epoxy resin has a mass percentage of 0.5wt% to 20wt%; or, in the liquid epoxy molding compound, the epoxy resin has a mass percentage of 1.0wt% to 15wt%; or, in the liquid epoxy molding compound, the epoxy resin has a mass percentage of 2.0wt% to 10wt%.

10. The liquid epoxy molding compound according to claim 6, characterized in that, The inorganic filler includes at least one of silicon dioxide, aluminum oxide, silicon nitride, boron nitride, aluminum nitride, and silicon carbide.

11. The liquid epoxy molding compound according to claim 10, characterized in that, The inorganic filler includes the silica, which is spherical silica with a particle size range of 1μm to 55μm, an average particle size of 1μm to 15μm, and a maximum particle size of 10μm to 55μm.

12. The liquid epoxy molding compound according to any one of claims 6 to 11, characterized in that, The liquid epoxy molding compound further includes a curing accelerator, wherein the curing accelerator has a mass percentage of 0.1 wt% to 5 wt%; and / or, The liquid epoxy molding compound further includes a coupling agent, wherein the coupling agent has a mass percentage of 0.1 wt% to 5 wt%; and / or, The liquid epoxy molding compound further includes a stress-relieving agent, wherein the stress-relieving agent has a mass percentage of 0.1wt% to 5wt%; and / or, The liquid epoxy molding compound further includes a diluent, wherein the diluent has a mass percentage of 0.1 wt% to 5 wt%; and / or, The liquid epoxy molding compound further includes a colorant, wherein the colorant has a mass percentage of 0.1 wt% to 1 wt%; and / or, The liquid epoxy molding compound also includes a defoamer, wherein the defoamer has a mass percentage of 0.01wt% to 0.5wt%.

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