Liquid molding underfill adhesive, method of making the same, and chip package structure

Abstract

This application discloses a liquid molding underfill adhesive and its preparation method, as well as a chip packaging structure. The liquid molding underfill adhesive includes epoxy resin, filler, and dispersion accelerator. The dispersion accelerator includes one of a low molecular weight quaternary ammonium salt and an alkyl ammonium salt of a polycarboxylic acid, wherein the number average molecular weight of the low molecular weight quaternary ammonium salt is 404 Da to 660 Da; the content of the dispersion accelerator is 0.049 wt% to 0.5 wt%, and the content of the epoxy resin is 10 wt% to 30 wt%; the epoxy resin includes at least one of aromatic epoxy resin and aliphatic epoxy resin, and the content of the filler is 65 wt% to 85 wt%; the liquid molding underfill adhesive also includes a curing agent, the content of which is 1 wt% to 4 wt%. The general structural formula of the alkyl ammonium salt of the polycarboxylic acid is as follows: R-(COO ‑ ) x ·[ + HNR' n ] x Where R is a hydrophobic hydrocarbon group or polymer chain, R' is an alkyl group or hydrogen; x≥2; n is 1~3. Low molecular weight quaternary ammonium salts are used to reduce powder agglomeration caused by electrostatics, or the strong steric hindrance of alkyl ammonium salts of polycarboxylic acids is used to stabilize particles and promote filler dispersion.

Description

Technical Field

[0001] This application relates to the field of chip packaging technology, specifically to a liquid molding bottom filler and its preparation method, and a chip packaging structure. Background Technology

[0002] High-performance storage products are rapidly evolving to meet the high demands of the AI ​​era. Smaller size, faster speeds, higher bandwidth, and better performance—these iterative trends will also bring new challenges to the development of next-generation products, namely, excessive heat generation. A new advanced packaging technology, Mass Reflow-Molded Underfill (MR-MUF), can effectively improve the heat dissipation performance of chips. MR-MUF advanced packaging technology utilizes a key packaging material, Liquid Molded Underfill (LMUF), which acts as a protective material to fill the gaps between chips, exhibiting excellent mechanical properties, electrical insulation, heat resistance, and high reliability.

[0003] Existing liquid molding underfill uses compression molding technology to achieve narrow gap filling and overall chip encapsulation. Compression molding technology requires the liquid molding underfill to reach the desired encapsulation position before curing. However, as the gaps between chips become increasingly narrow, voids (i.e., filling voids) may occur during the narrow gap filling process. Excessive void filling can lead to certain reliability risks. Summary of the Invention

[0004] This application provides a liquid molding bottom filler and its preparation method, as well as a chip packaging structure, aiming to solve the problem of excessive void filling.

[0005] This application provides a liquid molding underfill adhesive, comprising an epoxy resin, a filler, and a dispersion accelerator. The dispersion accelerator comprises one of a low molecular weight quaternary ammonium salt and an alkyl ammonium salt of a polycarboxylic acid, wherein the number average molecular weight of the low molecular weight quaternary ammonium salt is 404 Da to 660 Da; the content of the dispersion accelerator is 0.049 wt% to 0.5 wt%, and the content of the epoxy resin is 10 wt% to 30 wt%; the epoxy resin comprises at least one of an aromatic epoxy resin and an aliphatic epoxy resin, and the content of the filler is 65 wt% to 85 wt%; the liquid molding underfill adhesive further comprises a curing agent, the content of which is 1 wt% to 4 wt%; the general structural formula of the alkyl ammonium salt of the polycarboxylic acid is shown below: R-(COO - ) x ·[ + HNR' n ] x ; Where R is a hydrophobic hydrocarbon group or polymer chain, R' is an alkyl group or hydrogen; x ≥ 2; n is 1~3.

[0006] Optionally, in some embodiments of this application, the epoxy resin includes at least one of aromatic epoxy resin and aliphatic epoxy resin.

[0007] Optionally, in some embodiments of this application, the curing agent is an imidazole curing agent.

[0008] Optionally, in some embodiments of this application, the filler is an inorganic filler, which includes spherical silica.

[0009] Optionally, in some embodiments of this application, the liquid molding bottom filler further includes a silane coupling agent, the content of which is 0.2wt%~1wt%.

[0010] Optionally, in some embodiments of this application, the liquid molding bottom filler further includes a colorant, the content of which is 0.2wt%~1wt%.

[0011] Accordingly, this application also provides a method for preparing the aforementioned liquid molding underfill adhesive, comprising: stirring and mixing the epoxy resin, the filler and the dispersion accelerator to obtain the liquid molding underfill adhesive.

[0012] Optionally, in some embodiments of this application, the liquid molding underfill further includes a silane coupling agent, and the dispersion promoter includes the low molecular weight quaternary ammonium salt; the preparation method of the liquid molding underfill includes: premixing the low molecular weight quaternary ammonium salt and the silane coupling agent to obtain a premix; stirring and mixing the premix, the epoxy resin, and the filler to obtain the liquid molding underfill; and / or, The stirring temperature is 40℃~50℃, and the stirring time is 30min~60min.

[0013] In addition, this application also provides a chip packaging structure, including the cured product of the aforementioned liquid molding underfill or the cured product of the liquid molding underfill prepared by the aforementioned liquid molding underfill preparation method.

[0014] The liquid molding underfill provided in this application incorporates specific dispersion promoters: low molecular weight quaternary ammonium salts or alkyl ammonium salts of polycarboxylic acids. The low molecular weight quaternary ammonium salts reduce powder agglomeration caused by static electricity, promoting filler dispersion in the epoxy resin. Alternatively, the strong steric hindrance of the alkyl ammonium salts of polycarboxylic acids stabilizes the particles, preventing agglomeration and further promoting filler dispersion in the epoxy resin. This improves the rheological properties of the liquid molding underfill, increases its gelation time, and reduces its viscosity, resulting in fewer and smaller voids in the cured product. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view of the filling effect of the liquid molding bottom filler provided in Embodiment 1 of this application, showing the state of filling effect A; Figure 2 This is a cross-sectional view of the filling effect of the liquid molding bottom filler provided in Comparative Example 1 of this application, showing the state of filling effect B. Detailed Implementation

[0016] 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.

[0017] This application provides a liquid molding underfill adhesive and its preparation method, as well as a chip packaging structure. 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.

[0018] This application provides a liquid molding underfill adhesive, comprising an epoxy resin, a filler, and a dispersion accelerator. The dispersion accelerator comprises one of a low molecular weight quaternary ammonium salt and an alkyl ammonium salt of a polycarboxylic acid, wherein the number average molecular weight of the low molecular weight quaternary ammonium salt is 404 Da to 660 Da.

[0019] As an example, the number average molecular weights of low molecular weight quaternary ammonium salts are 404 Da, 450 Da, 500 Da, 550 Da, 600 Da, 650 Da, or 660 Da.

[0020] The liquid molding underfill provided in this application incorporates specific dispersion promoters: low molecular weight quaternary ammonium salts or alkyl ammonium salts of polycarboxylic acids. The low molecular weight quaternary ammonium salts reduce powder agglomeration caused by static electricity, promoting filler dispersion in the epoxy resin. Alternatively, the strong steric hindrance of the alkyl ammonium salts of polycarboxylic acids stabilizes the particles, preventing agglomeration and further promoting filler dispersion in the epoxy resin. This improves the rheological properties of the liquid molding underfill, increases its gelation time, and reduces its viscosity, resulting in fewer and smaller voids in the cured product.

[0021] In some embodiments of this application, the general structural formula of the alkylammonium salt of polycarboxylic acids is shown below: R-(COO - ) x ·[ + HNR' n ] x ; Where R is a hydrophobic hydrocarbon group or polymer chain, R' is an alkyl group or hydrogen; x ≥ 2; n is 1~3.

[0022] As an example, n is 1, 2, or 3.

[0023] As an example, alkylammonium salts of polycarboxylic acids that satisfy the above general structural formula include at least one of BYK-9076 and Coadd™ R-3150.

[0024] In some embodiments of this application, the content of the dispersion accelerator is 0.049 wt% to 0.5 wt%. The liquid molding underfill is an epoxy resin composition. The dispersion accelerator is mainly used to improve the dispersion effect of the filler. Increasing the content of the dispersion accelerator in the liquid molding underfill can increase the gelation time of the liquid molding underfill but decrease the viscosity. However, excessive content of the dispersion accelerator can lead to abnormal viscosity of the system, impaired curing performance, and decreased storage stability. As an example, the content of the dispersion accelerator is 0.049 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, or 0.5 wt%.

[0025] In some embodiments of this application, the epoxy resin includes at least one of aromatic epoxy resins and aliphatic epoxy resins. Aromatic epoxy resins include at least one of glycidyl ethers of phenols, glycidyl ether esters of hydroxycarboxylic acids, monoglycidyl esters or polyglycidyl esters of carboxylic acids, glycidylamine type epoxy compounds, epoxy compounds having a naphthalene skeleton, and phenolic resin compounds. One of these aromatic epoxy resins can be used alone, or two or more aromatic epoxy resins can be used. Aliphatic epoxy resins can impart flexibility to the cured product of the liquid molding underfill. Aliphatic epoxy resins include at least one of monofunctional aliphatic epoxy resins, difunctional aliphatic epoxy resins, and polyfunctional aliphatic epoxy resins. One of these aliphatic epoxy resins can be used alone, or two or more aliphatic epoxy resins can be used.

[0026] In some embodiments of this application, the epoxy resin content is 10wt% to 30wt%. As examples, the epoxy resin content is 10wt%, 15wt%, 20wt%, 25wt%, or 30wt%.

[0027] In some embodiments of this application, the filler is an inorganic filler. The inorganic filler includes at least one selected from silica, calcium carbonate, clay, alumina, silicon nitride, silicon carbide, boron nitride, calcium silicate, potassium titanate, aluminum nitride, beryllium, zirconium oxide, zirconium, phosphate rock, talc, spinel, mullite, titanium dioxide, aluminum hydroxide, magnesium hydroxide, zinc borate, and zinc molybdate. As an example, the inorganic filler includes silica, which includes at least one selected from fused silica and crystalline silica. From the perspective of increasing the filler content, the inorganic filler is selected from spherical silica.

[0028] In some embodiments of this application, the filler content is 65wt% to 85wt%. As examples, the filler content is 65wt%, 70wt%, 75wt%, 80wt%, or 85wt%.

[0029] In some embodiments of this application, the liquid molding underfill adhesive further includes a curing agent. Optionally, the curing agent is an imidazole-based curing agent. As an example, imidazole-based curing agents include at least one of 2-methylimidazole, 2-ethyl-4-methylimidazole, and 1-cyanoethyl-2-methylimidazole. Of course, in other embodiments, other curing agents besides imidazole-based curing agents may be selected, and this is not limited thereto.

[0030] In some embodiments of this application, the content of the curing agent is 1wt% to 4wt%. As an example, the content of the curing agent is 1wt%, 2wt%, 3wt%, or 4wt%.

[0031] In some embodiments of this application, the liquid molding underfill adhesive further includes a silane coupling agent. Optionally, the silane coupling agent includes γ-(2,3-epoxypropoxy)propyltrimethoxysilane, trimethyloxyphenylsilane, 3-aminopropyltriethoxysilane, 3-(isobutenoyloxy)propyltrimethoxysilane, vinyltrimethoxysilane, (3-aminopropyl)triethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-ureapropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-anilino ... At least one of ethoxysilane, γ-anilinopropylmethyldimethoxysilane, γ-anilinopropylmethyldiethoxysilane, γ-anilinopropylethyldiethoxysilane, γ-anilinopropylethyldimethoxysilane, γ-anilinomethyltrimethoxysilane, γ-anilinomethyltriethoxysilane, γ-anilinomethylmethyldimethoxysilane, γ-anilinomethylmethyldiethoxysilane, γ-anilinomethylethyldiethoxysilane, and γ-anilinomethylethyldimethoxysilane.

[0032] In some embodiments of this application, the content of the silane coupling agent is 0.2wt% to 1wt%. As examples, the content of the silane coupling agent is 0.2wt%, 0.4wt%, 0.6wt%, 0.8wt%, or 1wt%.

[0033] In some embodiments of this application, the liquid molding underfill further includes a colorant, the content of which is 0.2wt% to 1wt%. Optionally, the colorant is carbon black. As an example, the content of the colorant is 0.2wt%, 0.4wt%, 0.6wt%, 0.8wt%, or 1wt%.

[0034] In some embodiments of this application, the liquid molding underfill includes: epoxy resin, curing agent, filler, dispersion accelerator, silane coupling agent, and colorant; by weight, epoxy resin 10-30 parts, curing agent 2-6 parts, filler 70-80 parts, dispersion accelerator 0.05-0.5 parts, silane coupling agent 0.2-1 part, and colorant 0.2-1 part.

[0035] This application also provides a method for preparing the aforementioned liquid molding underfill adhesive, comprising: stirring and mixing epoxy resin, filler, and dispersion accelerator to obtain liquid molding underfill adhesive. Optionally, the stirring temperature is 40℃~50℃, for example 40℃, 42℃, 44℃, 46℃, 48℃, or 50℃; and the stirring time is 30min~60min, for example 30min, 40min, 50min, or 60min.

[0036] In some embodiments of this application, the liquid molding underfill adhesive further includes a silane coupling agent. The preparation method of the liquid molding underfill adhesive includes: premixing a dispersion accelerator and a silane coupling agent to obtain a premix; and stirring and mixing the premix, epoxy resin and filler to obtain the liquid molding underfill adhesive.

[0037] After pretreatment with low molecular weight quaternary ammonium salt and silane coupling agent, it is introduced into the formulation system. The low molecular weight quaternary ammonium salt can reduce powder agglomeration caused by static electricity, promote the further development of the silane coupling agent, promote filler dispersion, and improve the rheological properties of the bottom filler in liquid molding.

[0038] This application also provides a chip packaging structure, including a cured product of the aforementioned liquid molding underfill or a cured product of the liquid molding underfill prepared by the aforementioned method.

[0039] Because this liquid molding underfill has good dispersion characteristics and excellent rheological properties, it can reduce filling defects in chip packaging structures.

[0040] The following description is based on specific embodiments.

[0041] Example 1 Preparation of liquid molding underfill: 16 parts by weight of aromatic epoxy resin A1 (bisphenol A epoxy resin, epoxy equivalent 160 g / eq), 5 parts by weight of aliphatic epoxy resin A2 (diglycerol ether of aliphatic epoxy resin polytetramethyl glycol, epoxy equivalent 450 g / eq), 3.4 parts by weight of imidazole epoxy curing agent B (dimethylimidazole), 55 parts by weight of silica C1 (average particle size 300 nm), 20 parts by weight of silica C2 (average particle size 100 nm), 0.05 parts by weight of dispersion accelerator D1 (disdecyl dimethylammonium adipate, commercial brand name OSMORIN DA-50, number average molecular weight 587 Da), 0.3 parts by weight of silane coupling agent E (KH560), and 0.4 parts by weight of colorant F (carbon black) were mixed evenly and stirred at 50°C for 60 minutes to obtain the epoxy resin composition, i.e., the liquid molding underfill. In this mixture, silane coupling agent E and dispersion promoter D1 are premixed at 40°C for 10 min in a mass ratio of 6:1 and then added to the formulation.

[0042] Example 2 The difference between this embodiment and Embodiment 1 is that the dispersion accelerator D1 is 0.1 parts by weight. Everything else is the same as in Embodiment 1.

[0043] Example 3 The difference between this embodiment and Embodiment 1 is that the dispersion accelerator D1 is 0.2 parts by weight. Everything else is the same as in Embodiment 1.

[0044] Example 4 The difference between this embodiment and Embodiment 1 is that the dispersion accelerator D1 is 0.5 parts by weight. Everything else is the same as in Embodiment 1.

[0045] Example 5 The difference between this embodiment and Example 1 is that dispersion accelerator D2 is used instead of dispersion accelerator D1. Dispersion accelerator D2 is an alkylammonium salt of polycarboxylic acid BYK-9076 (manufactured by BYK Chemicals, Germany). Otherwise, it is the same as Example 1.

[0046] Example 6 The difference between this embodiment and Embodiment 5 is that the dispersion accelerator D2 is 0.1 parts by weight. Everything else is the same as in Embodiment 1.

[0047] Example 7 The difference between this embodiment and Embodiment 5 is that the dispersion accelerator D2 is 0.2 parts by weight. Everything else is the same as in Embodiment 1.

[0048] Example 8 The difference between this embodiment and Embodiment 5 is that the dispersion accelerator D2 is 0.5 parts by weight. Everything else is the same as in Embodiment 1.

[0049] Example 9 The difference between this embodiment and Example 1 is that the silane coupling agent E and the dispersion promoter D1 were not premixed. Everything else is the same as in Example 1.

[0050] Example 10 The difference between this embodiment and Example 1 is that the dispersion promoter D1 is docosyltrimethylammonium chloride (CAS: 17301-53-0, number average molecular weight 404 Da). Everything else is the same as in Example 1.

[0051] Example 11 The difference between this embodiment and Example 1 is that the dispersion promoter D1 is quaternary ammonium salt-70 (CAS: 68921-83-5, number average molecular weight is 660 Da). Everything else is the same as in Example 1.

[0052] Example 12 The difference between this embodiment and Example 5 is that the dispersion promoter D2 is the alkylammonium salt of polycarboxylic acid, Coadd™ R-3150 (manufactured by Polywill), otherwise it is the same as Example 5.

[0053] Comparative Example 1 The difference between this embodiment and Embodiment 1 is that the dispersion accelerator D1 is omitted. Everything else is the same as in Embodiment 1.

[0054] Comparative Example 2 The difference between this embodiment and Example 4 is that dispersion accelerator D3 is used instead of dispersion accelerator D1. Dispersion accelerator D3 is polydiallyldimethylammonium chloride (product brand name Sigma 409030, number average molecular weight is approximately 200 kDa). Everything else is the same as in Example 1.

[0055] Comparative Example 3 The difference between this embodiment and Example 4 is that dispersion accelerator D4 is used instead of dispersion accelerator D1, and silane coupling agent E and dispersion accelerator D4 are not premixed. Dispersion accelerator D4 is hexadecyltrimethylammonium chloride (CAS: 112-02-7, number average molecular weight 320 Da). Everything else is the same as in Example 1.

[0056] Please refer to Table 1 for the formulations of the liquid molding bottom filler prepared in the above embodiments and comparative examples.

[0057] Table 1

[0058] Performance testing: 1. Gel time: The gel time of the sample was tested using a rheometer. Specifically, the temperature was kept constant at 120℃ and the shear rate was 251 / s. The time required for the viscosity of the liquid molding bottom filler to reach 100 Pa·s was taken as the gel time.

[0059] 2. Viscosity measurement: The viscosity was measured using an E-type viscometer at a rate of 25 revolutions per minute. The unit of viscosity is Pa·s.

[0060] 3. Fill effect: The fill effect is confirmed by slicing analysis after molding.

[0061] The test results of the liquid molding bottom filler provided in each embodiment and comparative example are recorded in Table 2.

[0062] Table 2

[0063] Results analysis: As can be seen from Table 2, compared with Comparative Example 1 which did not add any dispersant accelerator, the liquid molding bottom filler prepared by Examples 1-4, 10-11 with dispersant accelerator D1 (low molecular weight quaternary ammonium salt) and Examples 5-8, 12 with dispersant accelerator D2 (alkyl ammonium salt of polycarboxylic acid) had a longer gelation time and lower viscosity, thus resulting in better filling effect.

[0064] In Examples 1-4, as the content of dispersant D1 in the liquid molding underfill increases, the gelation time of the liquid molding underfill increases, but the viscosity decreases. Examples 5-8 also show a similar trend: as the content of dispersant D2 in the liquid molding underfill increases, the gelation time of the liquid molding underfill increases, but the viscosity decreases.

[0065] The difference between Example 1 and Example 9 is that in Example 1, the silane coupling agent E and the dispersion accelerator D1 were premixed before being mixed with other components to obtain the liquid molding underfill adhesive, while in Example 9, all components were directly mixed together to obtain the liquid molding underfill adhesive. The results showed that, compared to Example 9, Example 1 had a longer gelation time and lower viscosity, resulting in better filling performance. This is because the premixing of silane coupling agent E and dispersion accelerator D1 allows dispersion accelerator D1 to promote the effect of silane coupling agent E, thereby improving filler dispersibility and enhancing the rheological properties of the liquid molding underfill adhesive.

[0066] Compared with Comparative Example 2, the number average molecular weight of the dispersion accelerator D3 in Comparative Example 2 is too large. Adding the dispersion accelerator D3 to the liquid molding underfill adhesive can increase the gelation time of the liquid molding underfill adhesive, but it also increases the viscosity of the liquid molding underfill adhesive, thus resulting in a poorer filling effect.

[0067] Compared with Comparative Example 3, although the number average molecular weight of the dispersion accelerator D4 in Comparative Example 3 is small, adding the dispersion accelerator D4 to the liquid molding underfill adhesive can increase the gelation time of the liquid molding underfill adhesive. However, since the silane coupling agent E and the dispersion accelerator D4 were not premixed, the filler dispersibility was poor, which in turn increased the viscosity of the liquid molding underfill adhesive and worsened the filling effect.

[0068] Compare Figure 1 and Figure 2 , Figure 1 The cured (dark gray) liquid molding filler adhesive in the bottom filler has few and small filling voids. Figure 2 The cured (dark gray) liquid molding filler has large and numerous voids.

[0069] The above provides a detailed description of a liquid molding bottom filler, its preparation method, and chip packaging structure 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 liquid molding underfill adhesive, characterized in that, The mixture includes epoxy resin, filler, and dispersion accelerator. The dispersion accelerator comprises one of a low molecular weight quaternary ammonium salt and an alkyl ammonium salt of a polycarboxylic acid, wherein the number average molecular weight of the low molecular weight quaternary ammonium salt is 404 Da to 660 Da; the content of the dispersion accelerator is 0.049 wt% to 0.5 wt%, the content of the epoxy resin is 10 wt% to 30 wt%, the content of the filler is 65 wt% to 85 wt%, and the liquid molding underfill further includes a curing agent, the content of which is 1 wt% to 4 wt%. The general structural formula of the alkyl ammonium salt of the polycarboxylic acid is shown below: R-(COO - ) x ·[ + HNR' n ] x ; Where R is a hydrophobic hydrocarbon group or polymer chain, R' is an alkyl group or hydrogen; x ≥ 2; n is 1~3.

2. The liquid molding bottom filler according to claim 1, characterized in that, The epoxy resin includes at least one of aromatic epoxy resin and aliphatic epoxy resin.

3. The liquid molding bottom filler according to claim 1, characterized in that, The filler is an inorganic filler, which includes spherical silica.

4. The liquid molding bottom filler according to claim 1, characterized in that, The curing agent is an imidazole-based curing agent.

5. The liquid molding bottom filler according to claim 1, characterized in that, The liquid molding bottom filler also includes a silane coupling agent, the content of which is 0.2wt%~1wt%.

6. The liquid molding bottom filler according to claim 1, characterized in that, The liquid molding underfill also includes a colorant, the content of which is 0.2wt%~1wt%.

7. The method for preparing the liquid molding underfill adhesive according to any one of claims 1 to 6, characterized in that, include: The epoxy resin, the filler, and the dispersion accelerator are stirred and mixed to obtain the liquid molding bottom filler.

8. The method for preparing the liquid molding bottom filler according to claim 7, characterized in that, The liquid molding underfill adhesive further includes a silane coupling agent, and the dispersion promoter includes the low molecular weight quaternary ammonium salt; the preparation method of the liquid molding underfill adhesive includes: premixing the low molecular weight quaternary ammonium salt and the silane coupling agent to obtain a premix, and stirring and mixing the premix, the epoxy resin and the filler to obtain the liquid molding underfill adhesive.

9. The method for preparing the liquid molding bottom filler according to claim 7, characterized in that, The stirring temperature is 40℃~50℃, and the stirring time is 30min~60min.

10. A chip packaging structure, characterized in that, This includes the cured liquid molding underfill as described in any one of claims 1 to 6, or the cured liquid molding underfill prepared by the method described in any one of claims 7 to 9.

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