Adjustable underfill adhesive and preparation method therefor, and chip packaging structure

Abstract

The present invention provides an adjustable underfill adhesive and a preparation method therefor, and a chip packaging structure. The underfill adhesive comprises the following components in mass percentage: 21-28% of a trifunctional epoxy resin, 8-19% of an amine curing agent, 54-66% of a filler, 0.2-0.4% of an accelerator, 0.1-0.3% of a silane coupling agent, and 0.1-0.2% of carbon black, wherein the molar ratio of the trifunctional epoxy resin to the amine curing agent is 1:0.7 to 1:1.4; and by controlling the molar ratio of the trifunctional epoxy resin to the amine curing agent to be 1:0.7 to 1:1.4, the glass transition temperature of the underfill adhesive can be controlled between 90°C and 180°C. In addition, by introducing the silane coupling agent, the degree of bonding between the filler and a thermosetting epoxy resin is improved, and thus the stability of the underfill adhesive is improved; moreover, an organic matrix-silane coupling agent-inorganic matrix bonding layer can be formed between an inorganic interface and an organic interface, so that the bonding strength of the underfill adhesive is improved, and thus the protection effect on a chip is enhanced.

Description

Adjustable bottom filling glue, preparation method thereof and chip packaging structure Technical Field

[0001] The present invention belongs to the technical field of bottom filling glue packaging, and in particular relates to an adjustable bottom filling glue, a preparation method thereof and a chip packaging structure. Background Art

[0002] Underfill is a material suitable for flip-chip underfill technology. It typically penetrates the gap between the chip and substrate through capillary action, then gradually solidifies through thermal curing to fill the gap between the chip and substrate, protecting the high-density solder bumps between the chip and substrate and the chip itself. However, existing underfills, after curing, lack sufficient adhesion to the chip, substrate, and solder bumps. They also have excessively high linear thermal expansion coefficients and insufficient glass transition temperatures. Consequently, the underfill material often cracks or peels off from the chip, substrate, and / or solder bumps, rendering it unable to protect the chip and causing damage.

[0003] Glass transition temperature (Tg) is a key material property. It is the temperature at which a material transitions from a glassy state to a highly elastic state and is the minimum temperature at which molecular chains can move. During the use of adhesives, a Tg that is too low or too high can affect the material's handling and processing temperature. Maintaining the Tg between 90°C and 180°C is crucial for the material's handling and processing.

[0004] Therefore, how to provide an adjustable bottom filling glue to enhance the protection effect of the chip is a technical problem that needs to be solved urgently by those skilled in the art.

[0005] Summary of the Invention

[0006] The object of the present invention is to provide an adjustable bottom filling glue, a preparation method thereof and a chip packaging structure, so as to solve at least one of the above-mentioned technical problems.

[0007] To achieve the above objectives, the first aspect of the present invention provides an adjustable underfill glue, which comprises the following components by mass percentage: 21%-28% trifunctional epoxy resin, 8%-19% amine curing agent, 54%-66% filler, 0.2%-0.4% accelerator, 0.1%-0.3% silane coupling agent, and 0.1%-0.2% carbon black; the molar ratio of the trifunctional epoxy resin to the amine curing agent is 1:0.7-1:1.4.

[0008] In the first aspect, the trifunctional epoxy resin has the structural formula:

[0009] In the first aspect, the amine curing agent includes at least one of triethylenetetramine, diethyltoluenediamine, and m-phenylenediamine.

[0010] In the first aspect, the filler comprises silicon dioxide; and the average particle size of the silicon dioxide is 0.6 μm to 3 μm.

[0011] In the first aspect, the accelerator includes an imidazole accelerator.

[0012] In the first aspect, the silane coupling agent includes at least one of γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane.

[0013] In the first aspect, the mass percentage of the silicon dioxide is 60%-65%, the mass percentage of the imidazole accelerator is 0.2%, the mass percentage of the silane coupling agent is 0.2%, and the mass percentage of the carbon black is 0.1%.

[0014] The second aspect of the present invention provides a method for preparing an adjustable bottom filling glue as described in the first aspect, the preparation method comprising: S1: stirring and mixing the components according to their respective mass percentages to obtain a first slurry, wherein the mass percentages of the components specifically include: 21%-28% trifunctional epoxy resin, 8%-19% amine curing agent, 54%-66% filler, 0.2%-0.4% accelerator, 0.1%-0.3% silane coupling agent, and 0.1%-0.2% carbon black; S2: transferring the first slurry to a three-roll grinder for dispersion treatment to obtain a uniformly dispersed second slurry; S3: vacuum degassing the second slurry to obtain a bottom filling glue.

[0015] In the second aspect, the molar ratio of the trifunctional epoxy resin to the amine curing agent is 1:0.7-1:1.4.

[0016] The third aspect of the present invention provides a chip packaging structure, comprising a substrate, a chip arranged on the substrate, and a plurality of spaced solder bumps arranged between the substrate and the chip and electrically connected to the substrate and the chip, a gap being formed between the substrate and the chip, and an adjustable bottom filling glue as described in the first aspect being arranged at the edge of the substrate so that the bottom filling glue flows from one end of the gap to the other end of the gap by capillary action to fill the gap; the bottom filling glue is cured at a curing temperature of 165°C and a curing time of 2 hours; after the curing is completed, a chip packaging structure is obtained. Beneficial effects:

[0017] The adjustable bottom filling glue provided by the present invention comprises the following components by mass percentage: 21%-28% of trifunctional epoxy resin, 8%-19% of amine curing agent, 54%-66% of filler, 0.2%-0.4% of accelerator, 0.1%-0.3% of silane coupling agent, and 0.1%-0.2% of carbon black; the molar ratio of the trifunctional epoxy resin to the amine curing agent is 1:0.7-1:1.4; when the molar ratio of the trifunctional epoxy resin to the amine curing agent is equal to 1:1, the epoxy group and the amino group react completely, and the cross-linked close bond of the formed thermosetting resin is formed. The glass transition temperature reaches the maximum value. By controlling the molar ratio of trifunctional epoxy resin and amine curing agent to 1:0.7-1:1.4, the glass transition temperature of the bottom filling glue can be controlled between 90-180°C. In addition, the introduction of silane coupling agent improves the bonding degree between the filler and the thermosetting epoxy resin, thereby improving the stability of the bottom filling glue, and can form an organic matrix-silane coupling agent-inorganic matrix bonding layer between the inorganic interface and the organic interface, thereby improving the bonding strength of the bottom filling glue and enhancing the protection effect on the chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] FIG1 is a flow chart of a method for preparing an adjustable bottom filling adhesive according to the present application. DETAILED DESCRIPTION

[0020] The present invention will be described in detail below in conjunction with specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific embodiments and examples are for illustrating the present invention, rather than for limiting the present invention.

[0021] Throughout this specification, unless otherwise specified, the terms used herein should be understood as having the same meaning as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the event of any conflict, the present specification shall take precedence.

[0022] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or obtained through existing methods.

[0023] The present application provides an adjustable bottom filling glue, which includes the following components by mass percentage: 21%-28% trifunctional epoxy resin, 8%-19% amine curing agent, 54%-66% filler, 0.2%-0.4% accelerator, 0.1%-0.3% silane coupling agent, and 0.1%-0.2% carbon black; the molar ratio of the trifunctional epoxy resin to the amine curing agent is 1:0.7-1:1.4.

[0024] The adjustable bottom filling glue provided by the present invention comprises the following components by mass percentage: 21%-28% of trifunctional epoxy resin, 8%-19% of amine curing agent, 54%-66% of filler, 0.2%-0.4% of accelerator, 0.1%-0.3% of silane coupling agent, and 0.1%-0.2% of carbon black; the molar ratio of the trifunctional epoxy resin to the amine curing agent is 1:0.7-1:1.4; when the molar ratio of the trifunctional epoxy resin to the amine curing agent is equal to 1:1, the epoxy group and the amino group react completely, and the cross-linked close bond of the formed thermosetting resin is formed. The glass transition temperature reaches the maximum value. By controlling the molar ratio of trifunctional epoxy resin and amine curing agent to 1:0.7-1:1.4, the glass transition temperature of the bottom filling glue can be controlled between 90-180°C. In addition, the introduction of silane coupling agent improves the bonding degree between the filler and the thermosetting epoxy resin, thereby improving the stability of the bottom filling glue, and can form an organic matrix-silane coupling agent-inorganic matrix bonding layer between the inorganic interface and the organic interface, thereby improving the bonding strength of the bottom filling glue and enhancing the protection effect on the chip.

[0025] In some possible embodiments, the trifunctional epoxy resin has the structural formula:

[0026] Trifunctional epoxy resins, as a material matrix, can provide adhesive and mechanical properties to underfills. Commercially available trifunctional epoxy resins include Jining Fangyu Chemical's TDE-85 (epoxy equivalent weight 100-125 g / eq) and Guangzhou Yihuisheng Chemical's CY-186 (epoxy equivalent weight 100-110 g / eq).

[0027] In some possible embodiments, the amine curing agent includes at least one of triethylenetetramine, diethyltoluenediamine, and m-phenylenediamine.

[0028] Amine curing agents react with trifunctional epoxy resins at a certain temperature and in the presence of an accelerator, resulting in a curing reaction that forms a thermosetting compound with a three-dimensional network structure. The amine curing agent can be any of triethylenetetramine (active hydrogen equivalent weight: 48 g / eq), diethyltoluenediamine (active hydrogen equivalent weight: 45 g / eq), and m-phenylenediamine (active hydrogen equivalent weight: 27 g / eq).

[0029] Reaction mechanism of amine curing agent and trifunctional epoxy resin:

[0030] When the epoxy resin: curing agent molar ratio is greater than 1:1, the epoxy groups are excessive and the concentration of amine groups is low. Amine-epoxy groups condense during the curing process. After the condensation reaction is completed, there are still excess epoxy groups that do not participate in the reaction. The cross-linking density is lower than that when the reaction is complete, which makes the Tg of the cured product smaller. In addition, the heat released during the curing process is low and cannot reach the temperature required for the homopolymerization of the remaining epoxy groups. Therefore, the excess epoxy groups do not participate in the reaction, and the final Tg is even smaller.

[0031] When the epoxy resin: curing agent molar ratio is equal to 1:1, the amino-epoxy reaction is complete, the cross-linking density is the highest, and Tg reaches the maximum value;

[0032] When the epoxy resin: curing agent molar ratio is less than 1:1, the amine groups are excessive and the concentration of amine groups is high. Amine-epoxy groups condense during the curing process, and the heat released during the curing process is high, reaching the temperature required for the homopolymerization of the epoxy resin groups. At the same time, some epoxy groups undergo homopolymerization, resulting in a lower crosslinking density, longer chain segments, and a lower Tg.

[0033] Based on this, the present application controls the glass transition temperature of the bottom filling glue by controlling the molar ratio of the trifunctional epoxy resin and the amine curing agent.

[0034] In some possible embodiments, the filler includes silicon dioxide; the average particle size of the silicon dioxide is 0.6 μm-3 μm.

[0035] As an inorganic filler, silicon dioxide can reduce the thermal expansion coefficient of the cured product and change the material modulus.

[0036] In some possible embodiments, the accelerator includes an imidazole accelerator.

[0037] The accelerator can accelerate the reaction rate of the trifunctional epoxy resin and the amine curing agent, reduce the curing time, and improve production efficiency; the accelerator can be an imidazole accelerator, preferably, the imidazole accelerator can be at least one of 4-methyl-2-phenylimidazole and 2-ethyl-4-methylimidazole.

[0038] In some possible embodiments, the silane coupling agent includes at least one of γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane.

[0039] Silane coupling agents can promote the connection between the underfill and the substrate, or the SiO2 or Si3N4 passivation layer on the chip surface, thereby improving the bonding strength and stability between the underfill and the substrate surface. In this application, the silane coupling agent includes at least one of γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane, which has an active primary amino functional group and three hydrolyzable methoxy or ethoxy groups. The primary amino functional group can react with an organic substance (epoxy group) to form a bond. The methoxy or ethoxy group, when hydrolyzed, generates a silanol, which combines with an inorganic substance to form a siloxane. This dual reactivity allows the silane coupling agent to enhance the bonding between the inorganic material (filler) and the organic polymer (thermosetting resin) through a bidirectional chemical reaction, thereby improving the stability of the underfill.

[0040] In some possible embodiments, the mass percentage of the silicon dioxide is 60%-65%, the mass percentage of the imidazole accelerator is 0.2%, the mass percentage of the silane coupling agent is 0.2%, and the mass percentage of the carbon black is 0.1%.

[0041] Based on a general inventive concept, the present application further provides a method for preparing the controllable underfill adhesive as described above, as shown in FIG1 . The method comprises:

[0042] S1: Stirring and mixing the components according to their respective mass percentages to obtain a first slurry, wherein the mass percentages of the components specifically include: 21%-28% trifunctional epoxy resin, 8%-19% amine curing agent, 54%-66% filler, 0.2%-0.4% accelerator, 0.1%-0.3% silane coupling agent, and 0.1%-0.2% carbon black; wherein the stirring time is 90-180s, the rotation speed is 1100r / min, and the revolution speed is 1450r / min;

[0043] S2: transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; wherein the feed gap in the three-roll mill is 20-45 μm and the discharge gap is 10-25 μm;

[0044] S3: vacuum degassing the second slurry to obtain an underfill adhesive; wherein the vacuum degassing is performed in a centrifugal mixer for 50-100 seconds, with a rotation speed of 1100 r / min and a revolution speed of 1450 r / min.

[0045] As another optional embodiment, the molar ratio of the trifunctional epoxy resin to the amine curing agent is 1:0.7-1:1.4.

[0046] Based on a general inventive concept, the present application further provides a chip packaging structure, comprising a substrate, a chip disposed on the substrate, and a plurality of solder bumps disposed between the substrate and the chip and electrically connected to the substrate and the chip, wherein a gap is formed between the substrate and the chip:

[0047] Disposing the adjustable underfill glue of the first aspect above at the edge of the substrate, so that the underfill glue flows from one end of the gap to the other end of the gap by capillary action to fill the gap;

[0048] The bottom filling glue liquid is cured at a curing temperature of 165° C. and a curing time of 2 hours;

[0049] After curing, a chip packaging structure is obtained.

[0050] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0051] The components of the underfill glue in Examples 1-6 and Comparative Examples 1-3 are shown in Table 1 below in terms of mass percentage:

[0052] Table 1 Raw material components by mass percentage

[0053] The storage modulus, glass transition temperature, thermal expansion coefficient, reaction enthalpy change, viscosity growth rate, and fluidity tests were performed on the underfills provided in Examples 1-6 and Comparative Examples 1-3. The specific test process is as follows:

[0054] 1. Storage modulus: Reference standard: ASTM E2254-2018, take a sample cured at 165°C for 2h, the size of the test sample is 55mm×10mm×2mm, and the measurement is carried out using DMA, measurement mode: dual cantilever mode, vibration frequency: 1Hz, amplitude: 10μm, heating rate: 5°C / min; the storage modulus takes the value of 25°C-245°C.

[0055] 2. Glass transition temperature Tg: Reference standard: ASTM E2254-2018, take a sample that is fully cured at 165°C for 2h, the prepared test sample size is 55mm×10mm×2mm, and the measurement is performed using DMA, measurement mode: dual cantilever mode, vibration frequency: 1Hz, amplitude: 10μm, heating rate: 5°C / min.

[0056] 3. Coefficient of thermal expansion: Reference standard: ASTM E831-2019, take a sample that is fully cured at 165℃ for 2h, and prepare a test sample with a size of 5mm×5mm×2mm. Use TMA (compression mode) to test the thermal expansion coefficient of the sample. TMA parameter settings: preload force: 0.05N, first scan: room temperature-220℃ (heating rate 10℃ / min); second scan: room temperature-220℃ (heating rate 10℃ / min), take the curve data of the second heating section; the thermal expansion coefficient CTE1 / 2 takes the values ​​of temperature at 50℃-90℃ and 160℃-200℃ respectively.

[0057] 4. Reaction enthalpy change: DSC instrument is used for testing, reference standard: GB / T 19466.3 / ISO11357-3, take 5-10 mg of sample (glue prepared by proportioning the above components), heating rate: 10℃ / min, room temperature -250℃.

[0058] 5. Viscosity growth rate: measured using a digital rotational viscometer (14# rotor, 20 r / min, room temperature)

[0059] 6. Fluidity test method: Attach a 20mm×20mm, 0.5mm thick square glass sheet to a glass slide with 50µm thick double-sided tape at the four corners. Place the sheet on a 90°C hot plate and preheat for three minutes. Use a fine steel needle to apply the underfill to be tested horizontally along one edge of the square glass sheet. Start timing at the same time. Under the action of capillary force, the underfill will flow to the bottom of the glass sheet. Note the time it takes to flow to half the side length (10mm) and the time it takes to fully flow (20mm).

[0060] The test results are shown in Table 2-3 below:

[0061] Table 2 Test results

[0062] Table 3 DSC test results

[0063] From the above table we can see that:

[0064] (1) In Comparative Example 1, the molar ratio of CY-186 to triethylenetetramine is greater than 1:1, the epoxy group is excessive, the concentration of the amino group is low, and the reaction heat is low, so there is excess CY-186 that does not react, and the final Tg is less than 90°C; no silane coupling agent is added, and the viscosity increases rapidly at room temperature for 24 hours, that is, the bottom filling glue prepared by the ratio of Comparative Example 1 is unstable; the glue of the configured bottom filling glue is horizontally applied along one edge of a square glass sheet. Under the action of capillary force, the glue flows at the bottom of the glass sheet. When it flows to 10 mm, it takes 126 seconds, and when it flows to 20 mm, it takes 580 seconds. It can be seen that the fluidity of this glue is poor;

[0065] (2) In Comparative Example 2, the molar ratio of CY-186 to triethylenetetramine is less than 1:1, the amino groups are excessive, the concentration of the amino groups is relatively high, the amino groups and the epoxy groups undergo condensation during the curing process, and the heat released during the curing process is high, reaching the temperature required for the homopolymerization of the epoxy groups. At the same time, a portion of the epoxy groups undergo homopolymerization, which reduces the crosslinking density and lengthens the chain segments, and the final Tg is less than 90°C. Without adding a silane coupling agent, the viscosity increases rapidly at room temperature for 24 hours, that is, the bottom filling glue prepared using the ratio of Comparative Example 2 is unstable. The fluidity test shows that the fluidity of this glue is poor.

[0066] (3) In Comparative Example 3, the molar ratio of CY-186 to triethylenetetramine is 1:0.95, and the Tg is between 90 and 180°C. However, no silane coupling agent is added. The viscosity increases rapidly over 24 hours at room temperature, indicating that the underfill glue prepared using the ratio of Comparative Example 3 is unstable. The fluidity test shows that the fluidity of this glue is poor.

[0067] (4) In Examples 1-3, the molar ratio of CY-186 to triethylenetetramine is greater than 1:1, the epoxy group is excessive, the concentration of the amino group is small, and the reaction heat is low, so there is excess CY-186 that does not react. However, the molar ratio of CY-186 to triethylenetetramine is greater than that of Comparative Example 1, so the Tg is between 90-180°C, and the silane coupling agent KH540 is added. The viscosity growth rate at room temperature for 24 hours is within 100%, that is, the bottom filling glue prepared using the ratio of Examples 1-3 has good stability; when performing a fluidity test, it can be found that the flow-through time is greatly shortened, that is, the glue in Examples 1-3 has good fluidity.

[0068] (5) In Example 4, the molar ratio of CY-186 to triethylenetetramine is equal to 1:1. At this time, the amino-epoxy reaction is complete, the crosslinking density is the highest, and the Tg reaches a maximum value of 180°C. Moreover, after adding the silane coupling agent KH540, the viscosity growth rate at room temperature for 24 hours is only 22.4%, which is the smallest among Examples 1-6. That is, when the molar ratio of CY-186 to triethylenetetramine is equal to 1:1, the Tg reaches a maximum value of 180°C. The stability of the underfill prepared using the ratio of Example 4 is the best;

[0069] (6) In Example 5-6, the molar ratio of CY-186 to triethylenetetramine is less than 1:1, the amino groups are excessive, the concentration of the amino groups is relatively high, the amino groups-epoxy groups undergo condensation during the curing process, and the heat released during the curing process is high, reaching the temperature required for the homopolymerization of the epoxy groups. At the same time, a part of the epoxy groups undergo homopolymerization reaction, which makes the crosslinking density smaller, the chain segments longer, and the Tg smaller. However, the molar ratio of CY-186 to triethylenetetramine in Example 5-6 is smaller than that in Comparative Example 2, so the Tg is greater than that in Comparative Example 2; the molar ratio of CY-186 to triethylenetetramine in Example 5-6 is larger than that in Example 4, so the Tg is smaller than that in Example 4, and the silane coupling agent KH540 is added to Example 5-6, and the viscosity growth rate at room temperature for 24 hours is within 100%, that is, the bottom filling glue prepared using the ratio of Example 5-6 has good stability;

[0070] In summary, the bottom filling glue prepared by the ratio in Examples 1-6 of the present application, due to the addition of silane coupling agent, controls the Tg between 90-180°C, and the viscosity growth rate at room temperature for 24 hours is also within 100%, showing good stability. When the fluidity test is performed, the flow extension time is greatly shortened compared with Comparative Examples 1-3, and the glue has excellent fluidity. That is, the present application provides a controllable, highly stable and fluid bottom filling glue, which is beneficial to improving the protection effect of the chip.

[0071] Finally, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0072] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0073] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. An adjustable bottom filling glue, characterized in that: The bottom filling glue comprises the following components by mass percentage: 21%-28% of trifunctional epoxy resin, 8%-19% of amine curing agent, 54%-66% of filler, 0.2%-0.4% of accelerator, 0.1%-0.3% of silane coupling agent, and 0.1%-0.2% of carbon black; the molar ratio of the trifunctional epoxy resin to the amine curing agent is 1:0.7-1:1.4; The filler includes silicon dioxide; the average particle size of the silicon dioxide is 0.6 μm-3 μm; The silane coupling agent includes at least one of γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane; The structural formula of the trifunctional epoxy resin is:

2. The adjustable bottom filling glue according to claim 1, characterized in that: The amine curing agent includes at least one of triethylenetetramine, diethyltoluenediamine and metaphenylenediamine.

3. The adjustable bottom filling glue according to claim 2, characterized in that: The accelerator includes an imidazole accelerator.

4. The adjustable bottom filling glue according to claim 3, characterized in that: The mass percentage of the silicon dioxide is 60%-65%, the mass percentage of the imidazole accelerator is 0.2%, the mass percentage of the silane coupling agent is 0.2%, and the mass percentage of the carbon black is 0.1%.

5. A method for preparing an adjustable bottom filling adhesive as claimed in any one of claims 1 to 4, characterized in that: The preparation method comprises: S1: Stir and mix the components according to their respective mass percentages to obtain a first slurry, The mass percentage of each component specifically includes: trifunctional epoxy resin 21%-28%, amine curing agent 8%-19%, filler 54%-66%, accelerator 0.2%-0.4%, silane coupling agent 0.1%-0.3%, carbon black 0.1%-0.2%; S2: transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; S3: vacuum degassing the second slurry to obtain bottom filling glue.

6. The preparation method according to claim 5, characterized in that: The molar ratio of the trifunctional epoxy resin to the amine curing agent is 1:0.7-1:1.

4.

7. A chip packaging structure, comprising a substrate, a chip disposed on the substrate, and a plurality of solder bumps disposed between the substrate and the chip and electrically connected to the substrate and the chip, wherein a gap is formed between the substrate and the chip, characterized in that: Disposing the adjustable bottom filling glue liquid of any one of claims 1 to 4 at the edge of the substrate, so that the bottom filling glue liquid flows from one end of the gap to the other end of the gap by capillary action to fill the gap; The bottom filling glue liquid is cured at a curing temperature of 165° C. and a curing time of 2 h; After curing, a chip packaging structure is obtained.

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