High-adhesion epoxy plastic encapsulating material with lignin and preparation method thereof

Abstract

The application belongs to the technical field of composite material packaging, and discloses high-adhesion epoxy plastic packaging material with lignin and a preparation method thereof. The epoxy plastic packaging material comprises the following components: a mixture of epoxy resin, phenolic resin and lignin, inorganic filler, coloring agent, release agent, curing accelerator, ion capture agent and coupling agent. The lignin is used to replace part of the phenolic resin, and the lignin and the phenolic resin are pre-fused in advance, so that the prepared epoxy plastic packaging material has the characteristics of improved glass transition temperature (Tg), high adhesion, high reliability, green environmental protection, reduced dependence on fossil fuels and realized sustainable development.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material packaging, in particular to a high-adhesion epoxy plastic packaging material with lignin and a preparation method thereof. BACKGROUND

[0002] Epoxy molding compound (EMC) is a kind of thermosetting composite material with epoxy resin as the matrix, which is widely used in chip packaging protection in the semiconductor industry. In the 1960s, with the rapid development of integrated circuit (IC) technology, traditional metal / ceramic packaging was gradually replaced by plastic packaging due to high cost and complex process. Epoxy molding compound has become the mainstream choice due to its excellent performance. In recent years, with the development of new technology industry, epoxy molding compound has been widely used in electronic packaging field, so the demand for composite material structure is becoming more and more extensive.

[0003] Among them, epoxy and phenolic resin curing agent as one of the main raw materials of epoxy molding compound, excellent mechanical properties and electrical properties are particularly important for the performance of packaging materials. The source mainly depends on petrochemical products, and the core raw materials come from derivatives of petroleum refining, mainly including bisphenol A (BPA), epoxy chloropropane (ECH), phenol (petroleum / coal) and formaldehyde (natural gas / coal) and so on. However, in recent years, with the overexploitation of fossil resources, the problems of resource depletion or carbon dioxide emission have increasingly serious impact on the environment. Using natural raw materials has become a research hotspot in the future, and exploring renewable resources (such as plant-based, waste-derived raw materials) to reduce dependence on fossil fuels. At the same time, it is also necessary to ensure the excellent mechanical properties and electrical properties of epoxy molding compound.

[0004] Patent CN118742588A discloses a sealing resin composition and a semiconductor device. The invention uses a phenolic curing agent obtained from plant-derived raw materials to prepare an epoxy resin composition with excellent practicality, such as flowability, curability, electrical reliability and other characteristics. Although the epoxy composition prepared by using the phenolic curing agent has excellent practicality, the preparation process of biomass modified phenolic resin is complex, which is not conducive to large-scale industrial production, and problems such as unstable production batch may occur. Compared with the original petroleum-based curing agent, the performance has not been significantly improved.

[0005] Therefore, the existing technology needs to be further developed and improved. In order to achieve sustainable development and environmental protection, more and more researches on bio-based alternatives to epoxy and phenolic resin are being carried out. Therefore, it is an urgent technical problem for those skilled in the art to select suitable biomass to replace epoxy or phenolic resin, to simplify the preparation process, to facilitate industrial development, and to ensure excellent performance. SUMMARY

[0006] The present application provides a kind of epoxy plastic encapsulation material with high adhesion of lignin and its preparation method, the epoxy plastic encapsulation material prepared has the characteristics of improving glass transition temperature (Tg), high adhesion, high reliability and green environmental protection, reduces dependence on fossil fuels, realizes sustainable development. Wherein, by lignin replacing part of phenolic resin curing agent provides a kind of high crosslinking density and high adhesion of epoxy plastic encapsulation material, the present application can provide a kind of EMC with high reliability to various forms of packaging known in the art, such as SOP, QFN, PDFN and SOT etc.

[0007] The present application is realized by the following technical solutions:

[0008] On the one hand, a kind of epoxy plastic encapsulation material with high adhesion of lignin is provided, which includes the following components by mass fraction: 4-10 parts of epoxy resin, 3-10 parts of a mixture of phenolic resin and lignin, 70-90 parts of inorganic filler, 0.1-0.3 parts of colorant, 0.2-0.6 parts of release agent, 0.1-0.5 parts of curing accelerator, 0.2-1.5 parts of ion capture agent, 0.1-0.3 parts of coupling agent.

[0009] Wherein, the mass ratio of phenolic resin to lignin is 2-10:1.

[0010] Preferably, the epoxy resin is selected from one or more of o-cresol formaldehyde type epoxy resin, dicyclopentadiene type epoxy resin, multi-aromatic epoxy resin, three functional group epoxy resin, four functional group epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin.

[0011] Preferably, the phenolic resin is selected from one or more of o-methyl phenolic resin, biphenyl phenolic resin, multi-aromatic phenolic resin, phenol aralkyl phenolic resin.

[0012] Preferably, the lignin is one or more of sulfate lignin, alkali lignin, organic solvent lignin, enzymatic hydrolysis lignin.

[0013] Preferably, the preparation method of enzymatic hydrolysis lignin is as follows:

[0014] The wood and straw are crushed and ground to 20-80 mesh, and the enzyme hydrolysis reaction is carried out at 30-50 DEG C, pH 4-5, using laccase + MnP cooperation for 36h; the temperature is raised to 80 DEG C, and the temperature is kept for 10min; the residue is removed by centrifugation or filtration, the pH is adjusted to 2-3, the lignin is collected by centrifugation after precipitation, extracted with ethyl acetate or dioxane, and finally the small molecular impurities are removed to prepare enzymatic hydrolysis lignin; the structural formula of the enzymatic hydrolysis lignin is:

[0015]

[0016] Preferably, the inorganic filler is selected from one or more of crystalline silica, fused silica, spherical silica, alumina, talc, kaolin, carbon fiber, glass fiber.

[0017] Preferably, the colorant is carbon black commonly used in the art, without particular limitation.

[0018] Preferably, the release agent is selected from one of palm wax, montan acid ester wax, polyethylene wax, oxidized polyethylene wax, polyamide wax.

[0019] Preferably, the curing accelerator is selected from one or more of imidazole compound, tertiary amine compound, organic phosphine compound, amide compound.

[0020] Preferably, the ion capture agent is an anion capture agent.

[0021] Preferably, the coupling agent is one or more of methyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, methyltriethoxysilane.

[0022] In another aspect, a method for preparing high-adhesion epoxy plastic encapsulant with lignin is provided, the method comprising the following steps: first, weighing raw materials according to mass fraction, then, pre-fusing phenolic resin and lignin in a homogenizer, the pre-fusing temperature is 130-150℃, and the time is 2h; then, sequentially adding the pre-fused phenolic resin and lignin, epoxy resin, inorganic filler, colorant, release agent, curing accelerator, ion capture agent, and coupling agent into a high-speed mixer to obtain a premix;

[0023] Transferring the premix into an extruder for sufficient kneading and mixing, cooling, and crushing to obtain the high-adhesion epoxy plastic encapsulant with lignin; wherein the melting section temperature of the extruder is 100-130℃, and the extrusion temperature is 85-100℃.

[0024] In a third aspect, the present application provides a sustainable development application of the high-adhesion epoxy plastic encapsulant with lignin in integrated circuit packaging.

[0025] The present application has the following advantages:

[0026] (1) The present application provides that part of the phenolic resin is replaced by enzymatic hydrolysis lignin, which is a natural polymer from plants and can be biodegraded. Replacing petroleum-based phenolic resin can reduce carbon footprint. By introducing enzymatic hydrolysis lignin, the dependence on petrochemical resources is reduced, which meets the requirements of green and environmentally friendly manufacturing. At the same time, enzymatic hydrolysis lignin is abundant in source and lower in price, which lays an important foundation for future price competition advantage.

[0027] (2) Phenolic resin is used as a curing agent in the epoxy plastic encapsulant, and there is a problem of poor mechanical and thermal properties due to low crosslinking density. Enzymatic hydrolysis lignin is rich in functional groups such as phenolic hydroxyl, hydroxyl, methoxyl, carbonyl and carboxyl, and can be crosslinked with the epoxy group of the epoxy resin to replace part of the phenolic resin as a curing agent to improve the crosslinking density. Therefore, the enzymatic hydrolysis lignin can replace part of the phenolic resin to solve the problems of low crosslinking density and adhesion, and the glass transition temperature Tg of the prepared epoxy plastic encapsulant is significantly improved under the synergistic effect of the enzymatic hydrolysis lignin and the phenolic resin. At the same time, the enzymatic hydrolysis lignin contains rich polar groups, and the adhesion of the prepared epoxy plastic encapsulant to copper and silver is increased. Secondly, the aromatic ring structure of lignin gives it self-flame retardant properties, which can reduce the amount of traditional flame retardants (such as brominated epoxy resin), reduce smoke toxicity, and meet the green process.

[0028] (3) In order to avoid delamination and pores of the packaged product, the phenolic resin and the enzymatic hydrolysis lignin are sufficiently finely ground to increase the specific surface area of the resin, and pre-fusion is carried out in a homogenizer according to the proportion, so that the compatibility can be effectively improved and phase separation can be avoided. At the same time, the enzymatic hydrolysis lignin provided by the present application has high heat resistance compared with the phenolic resin, and in addition, all the coupling agents, adhesion agents and ion capture agents used in the present application are high-temperature resistant, which further improves the heat resistance of the epoxy plastic encapsulant, thereby reducing the internal stress of the epoxy plastic encapsulant with internal components during integrated circuit packaging, and is suitable for high-temperature packaging scenarios (such as automotive electronics), and improves the reliability of integrated circuit packaging. DETAILED DESCRIPTION

[0029] The content of the present application will be described in detail below. The present embodiment is implemented on the premise of the technical solution of the present application, and involves detailed implementation schemes and operation processes, but the protection scope of the present application is not limited to the following specific embodiments. The terms used in the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application.

[0030] The raw materials used are as follows:

[0031] Epoxy resin: naphthalene epoxy resin (DIC Corporation); biphenyl type epoxy resin (Mitsubishi Chemical).

[0032] Phenolic resin: phenol aralkyl phenolic resin (Meiwa Specialty Chemicals Co., Ltd.).

[0033] Inorganic filler: spherical silica (Jiangsu Lianrui New Material Co., Ltd.).

[0034] Colorant: carbon black (Sichuan Zhenghao Special Carbon Black Technology Co., Ltd.).

[0035] Release agent: oxidized polyethylene wax; palm wax (Shanghai Yuxiang).

[0036] Curing accelerator: triphenylphosphine-1,4-benzoquinone adduct (TPP-BQ) (Shanghai Huichuang).

[0037] Ion capture agent: anion capture agent (Ningbo Suliangtong).

[0038] Coupling agent: 3-mercaptopropyl trimethoxysilane and methyl trimethoxysilane (Chongyue Trade).

[0039] Preparation method of enzymatic lignin:

[0040] The wood and straw are crushed and ground into smaller particle sizes (20-80 mesh), and the enzymatic reaction is carried out at 30-50°C and pH 4-5 for 36 hours in the presence of laccase and MnP synergism, while the degradation efficiency is dynamically monitored; the temperature is raised to 80°C (10 minutes of incubation), and the residue (cellulose / hemicellulose) is removed by centrifugation or filtration, the pH is adjusted to 2-3, the lignin is precipitated and collected by centrifugation, and the enzymatic lignin is extracted with ethyl acetate or dioxane, and finally the small molecular impurities (such as monosaccharides and phenolic acids) are removed to obtain the enzymatic lignin.

[0041] Example 1

[0042] A high-adhesion epoxy plastic encapsulant with lignin and a preparation method thereof, the preparation method steps are as follows:

[0043] First, 3.9g of phenol aralkyl phenolic resin and 0.4g of enzymatic lignin are pre-fused in a homogenizer (130-150°C, 2h), and then 5.7g of naphthalene epoxy resin, 0.5g of biphenyl epoxy resin, 87.5g of spherical silica with a D90 of 75μm, 0.18g of palm wax, 0.3g of oxidized polyethylene wax, 0.3g of methyl trimethoxysilane, 0.2g of 3-mercaptopropyl trimethoxysilane, 0.22g of carbon black, 0.5g of anion capture agent, and 0.3g of TPP-BQ are sequentially added to a high-speed mixer to obtain a premix;

[0044] The premix is transferred to an extruder for thorough kneading and mixing, cooled and crushed to obtain a high-adhesion epoxy plastic encapsulant with lignin; the melting section temperature of the extruder is 100-130°C, and the extrusion temperature is 85-100°C. The extruded material is naturally cooled, crushed to obtain a powder, pre-formed into a cake, and an epoxy plastic encapsulant with enzymatic lignin is obtained.

[0045] Example 2

[0046] A high-adhesion epoxy plastic encapsulant with lignin and a preparation method thereof, the preparation method steps are as follows:

[0047] Firstly, 3.7g phenol aralkyl phenolic resin, 0.6g enzymatic hydrolysis lignin are pre-melted by homogenizer (130-150℃, 2h), then 5.7g naphthalene epoxy resin, 0.5g biphenyl epoxy resin, 87.5g spherical silica with D90 of 75μm, 0.18g palm wax, 0.3g oxidized polyethylene wax, 0.3g methyl trimethoxysilane, 0.2g 3-mercaptopropyl trimethoxysilane, 0.22g carbon black, 0.5g anionic capture agent, 0.3g TPP-BQ are sequentially added into a high-speed mixer to obtain a premix;

[0048] The premix is transferred into an extruder for sufficient kneading and mixing, and then cooled and crushed to obtain the high-adhesion epoxy plastic encapsulating material with lignin; the melting section temperature of the extruder is 100-130℃, and the extrusion temperature is 85-100℃. The extruded material is naturally cooled, crushed to obtain a powder, pre-formed into a cake to obtain the epoxy plastic encapsulating material with enzymatic hydrolysis lignin.

[0049] Example 3

[0050] A high-adhesion epoxy plastic encapsulating material with lignin and a preparation method thereof, the preparation method comprising the following steps:

[0051] Firstly, 3.5g phenol aralkyl phenolic resin, 0.8g enzymatic hydrolysis lignin are pre-melted by homogenizer (130-150℃, 2h), then 5.7g naphthalene epoxy resin, 0.5g biphenyl epoxy resin, 87.5g spherical silica with D90 of 75μm, 0.18g palm wax, 0.3g oxidized polyethylene wax, 0.3g methyl trimethoxysilane, 0.2g 3-mercaptopropyl trimethoxysilane, 0.22g carbon black, 0.5g anionic capture agent, 0.3g TPP-BQ are sequentially added into a high-speed mixer to obtain a premix;

[0052] The premix is transferred into an extruder for sufficient kneading and mixing, and then cooled and crushed to obtain the high-adhesion epoxy plastic encapsulating material with lignin; the melting section temperature of the extruder is 100-130℃, and the extrusion temperature is 85-100℃. The extruded material is naturally cooled, crushed to obtain a powder, pre-formed into a cake to obtain the epoxy plastic encapsulating material with enzymatic hydrolysis lignin.

[0053] Example 4

[0054] A high-adhesion epoxy plastic encapsulating material with lignin and a preparation method thereof, the preparation method comprising the following steps:

[0055] Firstly, 3.3 g of phenol aralkyl phenolic resin and 1 g of enzymatic lignin are pre-melted by a homogenizer (130-150℃, 2h), and then 5.7 g of naphthalene epoxy resin, 0.5 g of biphenyl epoxy resin, 87.5 g of spherical silica with D90 of 75 μm, 0.18 g of palm wax, 0.3 g of oxidized polyethylene wax, 0.3 g of methyl trimethoxysilane, 0.2 g of 3-mercaptopropyl trimethoxysilane, 0.22 g of carbon black, 0.5 g of anionic capture agent, and 0.3 g of TPP-BQ are sequentially added into a high-speed mixer to obtain a premix;

[0056] The premix is transferred into an extruder for sufficient kneading and mixing, and then cooled and crushed to obtain a high-adhesion epoxy plastic encapsulating material with lignin; the melting section temperature of the extruder is 100-130℃, and the extrusion temperature is 85-100℃. The extruded material is naturally cooled, crushed into powder, pre-formed into a cake, and then an epoxy plastic encapsulating material with lignin is obtained.

[0057] Comparative Example 1

[0058] The difference from Example 3 is that the enzymatic lignin is omitted, and the specific steps are as follows:

[0059] 5.7 g of naphthalene epoxy resin, 0.5 g of biphenyl epoxy resin, 4.3 g of phenol aralkyl phenolic resin, 87.5 g of spherical silica with D90 of 75 μm, 0.18 g of palm wax, 0.3 g of oxidized polyethylene wax, 0.3 g of methyl trimethoxysilane, 0.2 g of 3-mercaptopropyl trimethoxysilane, 0.22 g of carbon black, 0.5 g of anionic capture agent, and 0.3 g of TPP-BQ are sequentially added into a high-speed mixer to obtain a premix;

[0060] The premix is transferred into an extruder for sufficient kneading and mixing, and then cooled and crushed to obtain a high-adhesion epoxy plastic encapsulating material with lignin; the melting section temperature of the extruder is 100-130℃, and the extrusion temperature is 85-100℃. The extruded material is naturally cooled, crushed into powder, pre-formed into a cake, and then an epoxy plastic encapsulating material with lignin is obtained.

[0061] Comparative Example 2

[0062] The difference from Example 3 is that the pre-melting step of phenol aralkyl phenolic resin and enzymatic lignin is omitted, and the specific steps are as follows:

[0063] 5.7 g naphthalene epoxy resin, 0.5 g biphenyl epoxy resin, 3.5 g phenol aralkyl phenolic resin, 0.8 g enzymatic lignin, 87.5 g spherical silica with D90 of 75 μm, 0.18 g palm wax, 0.3 g oxidized polyethylene wax, 0.3 g methyl trimethoxysilane, 0.2 g 3-mercaptopropyl trimethoxysilane, 0.22 g carbon black, 0.5 g anionic trapping agent, 0.3 g TPP-BQ were sequentially added into a high-speed mixer to obtain a premix;

[0064] The premix was transferred into an extruder for sufficient kneading and mixing, and then cooled and crushed to obtain a high-adhesion epoxy plastic encapsulating material with lignin; the melting section temperature of the extruder was 100-130 °C, and the extrusion temperature was 85-100 °C. The extruded material was naturally cooled, crushed to obtain a powder, preformed into a cake, and an epoxy plastic encapsulating material with enzymatic lignin was obtained.

[0065] Comparative Example 3

[0066] The difference from Example 3 is that the phenol aralkyl phenolic resin is omitted, and the specific steps are as follows:

[0067] 5.7 g naphthalene epoxy resin, 0.5 g biphenyl epoxy resin, 4.3 g enzymatic lignin, 87.5 g spherical silica with D90 of 75 μm, 0.18 g palm wax, 0.3 g oxidized polyethylene wax, 0.3 g methyl trimethoxysilane, 0.2 g 3-mercaptopropyl trimethoxysilane, 0.22 g carbon black, 0.5 g anionic trapping agent, 0.3 g TPP-BQ were sequentially added into a high-speed mixer to obtain a premix;

[0068] The premix was transferred into an extruder for sufficient kneading and mixing, and then cooled and crushed to obtain a high-adhesion epoxy plastic encapsulating material with lignin; the melting section temperature of the extruder was 100-130 °C, and the extrusion temperature was 85-100 °C. The extruded material was naturally cooled, crushed to obtain a powder, preformed into a cake, and an epoxy plastic encapsulating material with enzymatic lignin was obtained.

[0069] The epoxy plastic encapsulating material was evaluated mainly by the following test methods:

[0070] The specific test process is as follows:

[0071] 1. According to the standard GB / T40564-2021 "Epoxy Plastic Encapsulating Material for Electronic Packaging", the spiral flow length, gelation time, flash, viscosity, strength modulus, thermal hardness, appearance detection and thermal conductivity of the epoxy resin composition prepared in Examples 1-5 and Comparative Examples 1-2 were determined;

[0072] 2. Autoclave test (PCT): refer to the standard GB / T 40564-2021, temperature 121℃, humidity 100%, two standard atmospheres for 120 hours, weigh the mass of the sample before and after the test, calculate the water absorption. Sample size requirements: diameter: 50±1mm, thickness: 3±0.2mm;

[0073] 3. TMA test (Tg): using static thermal mechanical analyzer (TMA) to determine the glass transition temperature (Tg) of epoxy encapsulating material in bending mode, the size of the test sample is 4x4x10mm, the starting temperature is 25℃, the heating rate is 5℃ / min, the final temperature is 220℃, and the scanning starts;

[0074] 4. Adhesion test: using a molding machine to mold the obtained EMC cake on different substrate surfaces under the conditions of mold temperature 175±2℃, injection pressure 7.0±0.2MPa, and curing time 120 seconds, respectively selecting copper substrate and silver-plated substrate. According to SEMI G69-0996 standard, apply shear force along the surface of the sample at a speed of 10mm / min, test the maximum value before the encapsulating material and the sample are separated, the number of each test sample is 10, and the average value of the 10 test results is taken as the adhesion test result of each example;

[0075] 5. Flame resistance test: lay a layer of degreasing cotton with a thickness of about 6.4mm under the alcohol lamp, ignite the alcohol lamp and adjust the flame color until the height is 19mm; use a clamp to clamp at a distance of 6.4mm from the end of the sample, vertically into the center of the flame for 10 seconds, after 10 seconds, move the sample out of the flame at least 152mm, and record the Flaming and Glowing time of the sample with a stopwatch. When it is extinguished, immediately contact the flame again at the same point for 10 seconds, then move the sample out of the flame at least 152mm, and record the Flaming and Glowing time of the sample with a stopwatch. 5 samples need to be tested, a total of 10 groups of data.

[0076] The test results are shown in Table 1:

[0077] Table 1 Test Results

[0078]

[0079]

[0080] From the above table, examples 1-4 and comparative example 1 can be seen that the addition of enzymatic lignin, the flowability, glass transition temperature and copper silver binding force have a trend of improvement; examples 1-4 show that with the increase of the amount of enzymatic lignin added, the above performances are obviously improved, and after the addition of 0.8g, the performance remains stable, therefore, it is shown that the ratio relationship between phenolic aralkyl phenolic resin and enzymatic lignin affects the performance of epoxy plastic packaging material, and the epoxy plastic packaging material prepared within the fixed ratio range has good performance, and the epoxy plastic packaging material is better when the mass ratio of phenolic aralkyl phenolic resin to enzymatic lignin is 3.5:0.8, such as good copper silver adhesion and glass transition temperature.

[0081] In addition, from example 3 and comparative example 2, it can be seen that the pre-melting of enzymatic lignin and phenolic aralkyl phenolic resin plays a key role in the comprehensive performance of the packaging product, and if the softening point of enzymatic lignin is too high, the pre-melting and mixing will not be sufficient, and the packaging product will have delamination and pores. Therefore, the preparation process temperature and resin fineness significantly improve the mixing property, and there is no delamination and pore problem in the packaging process, and the product has excellent stability.

[0082] From example 3 and comparative example 3, it can be seen that although enzymatic lignin is rich in functional groups such as phenolic hydroxyl, hydroxyl, methoxyl, carbonyl and carboxyl, which can cross-link with the epoxy group of epoxy resin to increase the cross-linking density, but using all enzymatic lignin to replace phenolic resin, the material will be dry and hard to mix evenly during the mixing process, resulting in poor flowability, so only the synergistic effect of enzymatic lignin and phenolic aralkyl phenolic resin can make the prepared epoxy plastic packaging material have good performance.

[0083] The addition of enzymatic lignin with a suitable ratio in the system increases the adhesion of the prepared epoxy plastic packaging material to copper and silver. Secondly, the aromatic ring structure of lignin gives it self-retardant properties, which can reduce the amount of traditional flame retardant (such as brominated epoxy resin), reduce smoke toxicity, meet green process, and improve flame retardant performance.

[0084] Those skilled in the art will understand that the above discussion of any of the embodiments is only exemplary and is not intended to suggest that the scope of the present application is limited to these examples; under the idea of the present application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above. In order to be brief, they are not provided in detail.

Claims

1. A high-adhesion epoxy molding compound with lignin, characterized in that, The product comprises the following components by weight: 4-10 parts epoxy resin, 3-10 parts a mixture of phenolic resin and lignin, 70-90 parts inorganic filler, 0.1-0.3 parts colorant, 0.2-0.6 parts release agent, 0.1-0.5 parts curing accelerator, 0.2-1.5 parts ion scavenger, and 0.1-0.3 parts coupling agent; The mass ratio of phenolic resin to lignin is 2-10:

1. The preparation method of epoxy molding compound includes the following steps: First, weigh the raw materials according to the mass fraction. Then, pre-melt the phenolic resin and lignin in a homogenizer at a temperature of 130~150 ℃ for 2 h. After that, add the pre-melted phenolic resin and lignin, epoxy resin, inorganic filler, colorant, release agent, curing accelerator, ion scavenger, and coupling agent to a high-speed mixer in sequence to obtain a premix. The premixed material is transferred to an extruder, kneaded and mixed thoroughly, cooled and pulverized to obtain a high-adhesion epoxy sealant with lignin; wherein the melting section temperature of the extruder is 100~130 ℃ and the extrusion temperature is 85~100 ℃.

2. The lignin-based high-adhesion epoxy molding compound according to claim 1, characterized in that, The epoxy resin is selected from one or more of the following: o-cresol aldehyde epoxy resin, dicyclopentadiene epoxy resin, polyaromatic epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, biphenyl epoxy resin, and naphthalene-based epoxy resin.

3. The lignin-based high-adhesion epoxy molding compound according to claim 1, characterized in that, The phenolic resin is selected from one or more of o-methylphenolic resin, biphenyl phenolic resin, polyaromatic phenolic resin, and phenol arylalkyl phenolic resin.

4. The lignin-based high-adhesion epoxy molding compound according to claim 1, characterized in that, The lignin is one or more of sulfate lignin, alkali lignin, organic solvent lignin, and enzymatically hydrolyzed lignin.

5. The lignin-based high-adhesion epoxy molding compound according to claim 1, characterized in that, The inorganic filler is selected from one or more of crystalline silica, fused silica, spherical silica, alumina, talc, kaolin, carbon fiber, and glass fiber.

6. The lignin-based high-adhesion epoxy molding compound according to claim 1, characterized in that, The release agent is selected from one of palm wax, montmorillonite wax, polyethylene wax, oxidized polyethylene wax, and polyamide wax.

7. The lignin-based high-adhesion epoxy molding compound according to claim 1, characterized in that, The curing accelerator is selected from one or more imidazole compounds, tertiary amine compounds, organophosphorus compounds, and amide compounds.

8. The lignin-based high-adhesion epoxy molding compound according to claim 1, characterized in that, The coupling agent is one or more of methyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and methyltriethoxysilane.

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