A dispensing-stable underfill adhesive, a preparation method thereof and a chip package structure

Abstract

This invention provides a dispensing-stable underfill adhesive, its preparation method, and a chip packaging structure, relating to the field of chip packaging technology. The underfill adhesive comprises the following components by mass percentage: 60%-67% silica, 17%-21% epoxy resin, 14%-18% curing agent, 0.5%-2.5% thickener, 0.1%-0.3% accelerator, and 0.1%-0.3% carbon black; wherein the main component of the thickener is a modified polyurea compound. This invention improves the yield stress of the adhesive by introducing a modified polyurea compound into the epoxy system, making the adhesive less prone to deformation during the dispensing stage, thus improving the dispensing stability of the adhesive. This allows for more precise matching of the adhesive amount to the gap between the chip and the substrate, completing the dispensing and filling in one step, improving filling efficiency, and improving chip packaging efficiency.

Description

Technical Field

[0001] This invention belongs to the field of chip packaging technology, and specifically relates to a dispensing-stable underfill adhesive, its preparation method, and chip packaging structure. Background Technology

[0002] Underfill adhesive is a material used in flip chip underfill technology. It typically penetrates the gap between the chip and the substrate using capillary action, then gradually solidifies through thermosetting, filling the gap and protecting the high-density solder bumps and the chip itself. However, during chip packaging, the optimal amount of underfill adhesive used per chip is determined based on the chip size and the gap between it and the substrate. Therefore, if the underfill adhesive dispensing stability is poor, it can lead to significant deviations in the amount dispensed with each application. After multiple dispensing operations to complete one chip, the total amount dispensed will ultimately deviate significantly from the designed amount. Too little adhesive will fail to completely fill the bottom or adequately encapsulate the surrounding area, while too much adhesive will overflow, severely impacting the reliability of the chip packaging.

[0003] Therefore, how to provide a stable underfill adhesive by introducing a thickener into the system to increase the yield stress of the adhesive and thus improve the dispensing stability of the adhesive, so as to accurately control the dispensing amount, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a stable dispensing underfill adhesive, its preparation method, and a chip packaging structure, so as to solve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, the first aspect of the present invention provides a dispensing-stable underfill adhesive, wherein the underfill adhesive comprises the following components by weight percentage: 60%-67% silica, 17%-21% epoxy resin, 14%-18% curing agent, 0.5%-2.5% thickener, 0.1%-0.3% accelerator, and 0.1%-0.3% carbon black; wherein the main component of the thickener is a modified polyurea compound.

[0006] In the first aspect, the silica has a mass percentage of 63%, and the epoxy resin has a mass percentage of 17%-19%.

[0007] In the first aspect, the curing agent has a mass percentage of 16% to 18%, the accelerator has a mass percentage of 0.2%, and the carbon black has a mass percentage of 0.2%.

[0008] In the first aspect, the thickener includes at least one of CO-627, BYK-410, and BYK-420.

[0009] In the first aspect, the epoxy resin is a bisphenol A type epoxy resin or a bisphenol F type epoxy resin.

[0010] In the first aspect, the curing agent is an amine curing agent, which includes at least one of triethylenetetramine, polyetheramine, and m-phenylenediamine.

[0011] In the first aspect, the accelerator includes at least one of amine accelerators and imidazole accelerators.

[0012] In the first aspect, the amine accelerator includes N,N-dimethylbenzylamine; the imidazole accelerator includes 1-cyanoethyl-2-ethyl-4-methylimidazole.

[0013] The second aspect of this invention provides a method for preparing a dispensing-stabilized underfill adhesive. The method includes: weighing each component of the raw materials according to the mass percentage of the dispensing-stabilized underfill adhesive described in the first aspect, and placing them in a mixing cup to obtain a first slurry; stirring the first slurry using a first centrifugal mixer to obtain a uniformly mixed second slurry; the operating parameters of the first centrifugal mixer include: stirring time of 115-220 s, rotation speed of 2650 r / min, and revolution speed of 2100 r / min; transferring the second slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed third slurry; the operating parameters of the three-roll mill include: feed gap of 10-20 μm and discharge gap of 2-6 μm; and vacuum degassing the third slurry using a second centrifugal mixer to obtain the underfill adhesive; the operating parameters of the second centrifugal mixer include: stirring time of 70-100 s, rotation speed of 1850 r / min, and revolution speed of 1500 r / min.

[0014] A third aspect of the present invention provides a chip packaging structure, including a substrate, a chip disposed on the substrate, and a plurality of spaced solder bumps disposed between the substrate and the chip and electrically connected to the substrate and the chip. A gap is formed between the substrate and the chip. An underfill adhesive solution of the dispensing-stabilized type described in the first aspect is disposed at the edge of the substrate, so that the underfill adhesive solution flows from one end of the gap to the other end of the gap through capillary action to fill the gap. The underfill adhesive solution is cured. After curing, the chip packaging structure is obtained.

[0015] Beneficial effects:

[0016] This invention provides a dispensing-stabilized underfill adhesive, comprising the following components by weight percentage: 60%-67% silica, 17%-21% epoxy resin, 14%-18% curing agent, 0.5%-2.5% thickener, 0.1%-0.3% accelerator, and 0.1%-0.3% carbon black; wherein the thickener is primarily a modified polyurea compound; by using epoxy resin as the matrix material, silica as the filler material, and combining the curing agent and accelerator, the thickener-modified polyurea compound forms a three-dimensional network structure in the system to lock in the resin or low-molecular-weight components and prevent the adhesive from flowing freely under low shear force, thereby avoiding the adhesive from collapsing or overflowing at the dispensing edge, which would affect the reliability of chip packaging. This invention improves the yield stress of the adhesive by introducing a modified polyurea compound into the epoxy system, making the adhesive less prone to deformation during the dispensing and filling stage, thus improving the dispensing stability of the adhesive. This allows for more precise matching of the amount of adhesive between the chip and the substrate, completing the dispensing and filling in one step, improving filling efficiency, and improving chip packaging efficiency. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram showing the yield stress determination curves of the bottom filler prepared in Example 1 and Comparative Example 1 of this invention. Detailed Implementation

[0019] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0020] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning 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 pertains. In the event of any conflict, this specification shall prevail.

[0021] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be obtained by purchasing them from the market or by existing methods.

[0022] The present invention provides a dispensing-stabilized underfill adhesive, wherein the underfill adhesive comprises the following components by weight percentage: 60%-67% silica, 17%-21% epoxy resin, 14%-18% curing agent, 0.5%-2.5% thickener, 0.1%-0.3% accelerator, and 0.1%-0.3% carbon black; wherein the main component of the thickener is a modified polyurea compound.

[0023] Specifically, the present invention provides a dispensing-stabilized underfill adhesive comprising the following components by weight percentage: 60%-67% silica, 17%-21% epoxy resin, 14%-18% curing agent, 0.5%-2.5% thickener, 0.1%-0.3% accelerator, and 0.1%-0.3% carbon black; wherein the thickener is primarily a modified polyurea compound; by using epoxy resin as the matrix material, silica as the filler material, and combining the curing agent and accelerator, the thickener-modified polyurea compound forms a three-dimensional network structure in the system to lock the resin or low-molecular-weight components in the system and prevent the adhesive from flowing freely under low shear force, thereby avoiding the adhesive from collapsing or overflowing at the dispensing edge, which would affect the reliability of chip packaging. This invention improves the yield stress of the adhesive by introducing a modified polyurea compound into the epoxy system, making the adhesive less prone to deformation during the dispensing and filling stage, thus improving the dispensing stability of the adhesive. This allows for more precise matching of the amount of adhesive between the chip and the substrate, completing the dispensing and filling in one step, improving filling efficiency, and improving chip packaging efficiency.

[0024] It should be added that yield stress refers to the minimum shear force required for the adhesive to begin to flow when subjected to external force. The influence of the adhesive's yield strength on dispensing stability is mainly reflected in the influence of the adhesive's fluidity, viscosity and other physical properties on the variability of the dispensing process. Adhesives with stronger yield strength are more likely to form stable flow when pressure is applied, reducing dispensing fluctuations and thus improving dispensing stability. Conversely, insufficient yield strength may lead to problems such as uneven adhesive flow and sticking.

[0025] In some possible embodiments, the silica has a mass percentage of 63% and the epoxy resin has a mass percentage of 17%-19%.

[0026] In some possible embodiments, the curing agent has a mass percentage of 16% to 18%, the accelerator has a mass percentage of 0.2%, and the carbon black has a mass percentage of 0.2%.

[0027] In some possible embodiments, the thickener includes at least one of CO-627, BYK-410, and BYK-420.

[0028] In this application, a modified polyurea compound thickener is used to form a three-dimensional network structure in the system through hydrogen bonding, molecular entanglement, or physical cross-linking to lock the resin or small molecule compounds in the adhesive system. This prevents the adhesive system from flowing freely under low shear force, improves the fluidity of the adhesive, and controls the dispensing stability. This allows the preset dispensing amount to fill the gap between the chip and the substrate in one go, which is beneficial for subsequent curing and molding and improves the reliability of chip packaging.

[0029] In some possible embodiments, the epoxy resin is a bisphenol A type epoxy resin or a bisphenol F type epoxy resin.

[0030] Those skilled in the art will understand that bisphenol A type epoxy resin and bisphenol F type epoxy resin are the simplest functional epoxy resins. By using a single, simple epoxy resin as the matrix material, the role of the thickener in this application can be more clearly understood, as well as how the thickener, epoxy resin, curing agent, and accelerator work synergistically to improve the dispensing stability of the adhesive and enhance the reliability of chip packaging.

[0031] In some possible embodiments, the curing agent is an amine curing agent, which includes at least one of triethylenetetramine, polyetheramine, and m-phenylenediamine.

[0032] In some possible embodiments, the accelerator includes at least one of amine accelerators and imidazole accelerators.

[0033] This is because the combination of curing agent and accelerator can transform the epoxy system from a rheological state to a solid state and increase the reaction rate.

[0034] In some possible embodiments, the amine accelerator includes N,N-dimethylbenzylamine; and the imidazole accelerator includes 1-cyanoethyl-2-ethyl-4-methylimidazole.

[0035] Based on a general inventive concept, a second aspect of the present invention provides a method for preparing a dispensing-stabilized underfill adhesive, the method comprising:

[0036] Weigh each component of the raw material according to the mass percentage of the dispensing stabilized bottom filler described in the first aspect, and place them in a mixing cup to obtain the first slurry;

[0037] The first slurry is stirred by a first centrifugal mixer to obtain a uniformly mixed second slurry; the operating parameters of the first centrifugal mixer include: stirring time of 115-220s, rotation of 2650r / min, and revolution of 2100r / min.

[0038] The second slurry is transferred to a three-roll mill for dispersion treatment to obtain a uniformly dispersed third slurry; the operating parameters of the three-roll mill include: feed gap of 10-20μm and discharge gap of 2-6μm;

[0039] The third slurry is vacuum degassed using a second centrifugal mixer to obtain a bottom filling adhesive. The operating parameters of the second centrifugal mixer include: mixing time of 70-100s, rotation of 1850r / min, and revolution of 1500r / min.

[0040] This invention provides a method for preparing a stable underfill adhesive. The method involves weighing each raw material component according to a specific formula ratio to ensure thorough mixing for subsequent cross-linking and curing. The thoroughly mixed slurry is then transferred to a three-roll mill for dispersion treatment to further improve the compatibility between the raw material components. Vacuum degassing is then performed to remove gases generated during mixing, resulting in a uniformly dispersed and flowable underfill adhesive. When using the underfill adhesive provided in this application for chip encapsulation, the adhesive can be uniformly distributed between the chip and the substrate, and the dispensing amount can be precisely controlled to match the gap to be filled. This allows for single-pass filling of the gap between the chip and the substrate, improving the uniformity of gap filling and thus enhancing the reliability of chip encapsulation.

[0041] Based on a general inventive concept, a third aspect of the present invention provides a chip packaging structure, including a substrate, a chip disposed on the substrate, and a plurality of spaced solder bumps disposed between the substrate and the chip and electrically connected to the substrate and the chip. A gap is formed between the substrate and the chip. An underfill adhesive solution of the dispensing-stabilized type described in the first aspect is disposed at the edge of the substrate, so that the underfill adhesive solution flows from one end of the gap to the other end of the gap through capillary action to fill the gap. The underfill adhesive solution is cured. After curing, a chip packaging structure is obtained.

[0042] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0043] The raw materials used in the examples and comparative examples are as follows:

[0044] Filler: Silica;

[0045] Epoxy resins: Bisphenol A type epoxy resin: grade E-44, grade YHY-518; Bisphenol F type epoxy resin: grades F44, F48, F51;

[0046] Curing agents: triethylenetetramine; polyetheramine; m-phenylenediamine;

[0047] Thickener: Modified polyurea compound: brand CO-627; brand BYK-410 or BYK-420;

[0048] Rosin thickener, brand name MX-1518;

[0049] Accelerators: N,N-dimethylbenzylamine; 1-cyanoethyl-2-ethyl-4-methylimidazole.

[0050] Example 1

[0051] The raw materials for the underfill adhesive, by weight percentage, include:

[0052] Silica: 63%, Epoxy Resin E-44: 18%, Curing Agent Polyetheramine: 17.1%, Thickener CO-627: 1.5%, Carbon Black: 0.2%, Accelerator N,N-Dimethylbenzylamine: 0.2%;

[0053] The specific steps for preparing the above-mentioned bottom filler are as follows:

[0054] (1) Weigh each component according to the mass percentage of each component of the bottom filler raw material and place them in a mixing cup to obtain the first slurry;

[0055] (2) The first slurry is stirred by the first centrifugal mixer for 200s, with a rotation of 2650r / min and a revolution of 2100r / min, to obtain a uniformly mixed second slurry;

[0056] (3) The second slurry is transferred to a three-roll mill for dispersion treatment to obtain a uniformly dispersed third slurry; the feed gap of the three rollers in the three-roll mill is set to 10 μm and the discharge gap is set to 5 μm.

[0057] (4) Set the vacuum degassing time of the third centrifugal mixer to 90s, the rotation to 1000r / min, and the revolution to 1250r / min. Vacuum degassing of the second slurry is performed by the third centrifugal mixer to obtain the bottom filling adhesive.

[0058] Example 2

[0059] The raw materials for the underfill adhesive, by weight percentage, include:

[0060] Silica: 63%, Epoxy Resin E-44: 17.5%, Curing Agent Polyetheramine: 16.6%, Thickener CO-627: 2.5%, Carbon Black: 0.2%, Accelerator N,N-Dimethylbenzylamine: 0.2%;

[0061] The preparation steps of the bottom filler in this embodiment are the same as in Embodiment 1.

[0062] Example 3

[0063] The raw materials for the underfill adhesive, by weight percentage, include:

[0064] Silica: 63%, Epoxy Resin E-44: 18.5%, Curing Agent Polyetheramine: 17.6%, Thickener CO-627: 0.5%, Carbon Black: 0.2%, Accelerator N,N-Dimethylbenzylamine: 0.2%;

[0065] The preparation steps of the bottom filler in this embodiment are the same as in Embodiment 1.

[0066] Example 4

[0067] The raw materials for the underfill adhesive, by weight percentage, include:

[0068] Silica: 63%, Epoxy Resin F-44: 18%, Curing Agent Polyetheramine: 17.1%, Thickener CO-627: 1.5%, Carbon Black: 0.2%, Accelerator N,N-Dimethylbenzylamine: 0.2%;

[0069] The preparation steps of the bottom filler in this embodiment are the same as in Embodiment 1.

[0070] Example 5

[0071] The raw materials for the underfill adhesive, by weight percentage, include:

[0072] Silica: 63%, Epoxy Resin F-44: 17.5%, Curing Agent Polyetheramine: 16.6%, Thickener CO-627: 2.5%, Carbon Black: 0.2%, Accelerator N,N-Dimethylbenzylamine: 0.2%;

[0073] The preparation steps of the bottom filler in this embodiment are the same as in Embodiment 1.

[0074] Example 6

[0075] The raw materials for the underfill adhesive, by weight percentage, include:

[0076] Silica: 63%, Epoxy Resin F-44: 18.5%, Curing Agent Polyetheramine: 17.6%, Thickener CO-627: 0.5%, Carbon Black: 0.2%, Accelerator N,N-Dimethylbenzylamine: 0.2%;

[0077] The preparation steps of the bottom filler in this embodiment are the same as in Embodiment 1.

[0078] Comparative Example 1

[0079] The raw materials for the underfill adhesive, by weight percentage, include:

[0080] Silica: 63%, Epoxy Resin E-44: 19%, Curing Agent Polyetheramine: 17.6%, Carbon Black: 0.2%, Accelerator N,N-Dimethylbenzylamine: 0.2%;

[0081] The preparation steps of the bottom filler in this comparative example are the same as in Example 1.

[0082] Comparative Example 2

[0083] The raw materials for the underfill adhesive, by weight percentage, include:

[0084] Silica: 63%, Epoxy Resin F-44: 19%, Curing Agent Polyetheramine: 17.6%, Carbon Black: 0.2%, Accelerator N,N-Dimethylbenzylamine: 0.2%;

[0085] The preparation steps of the bottom filler in this comparative example are the same as in Example 1.

[0086] Comparative Example 3

[0087] The raw materials for the underfill adhesive, by weight percentage, include:

[0088] Silica: 63%, Epoxy Resin E-44: 19%, Curing Agent Polyetheramine: 17.4%, Thickener CO-627: 0.2%, Carbon Black: 0.2%, Accelerator N,N-Dimethylbenzylamine: 0.2%;

[0089] The preparation steps of the bottom filler in this comparative example are the same as in Example 1.

[0090] Comparative Example 4

[0091] The raw materials for the underfill adhesive, by weight percentage, include:

[0092] Silica: 63%, Epoxy Resin E-44: 18%, Curing Agent Polyetheramine: 15.6%, Thickener CO-627: 3%, Carbon Black: 0.2%, Accelerator N,N-Dimethylbenzylamine: 0.2%;

[0093] The preparation steps of the bottom filler in this comparative example are the same as in Example 1.

[0094] Comparative Example 5

[0095] The raw materials for the underfill adhesive, by weight percentage, include:

[0096] Silica: 63%, Epoxy Resin E-44: 18%, Curing Agent Polyetheramine: 17.1%, Thickener MX-1518: 1.5%, Carbon Black: 0.2%, Accelerator N,N-Dimethylbenzylamine: 0.2%;

[0097] The preparation steps of the bottom filler in this comparative example are the same as in Example 1.

[0098] Comparative Example 6

[0099] The raw materials for the underfill adhesive, by weight percentage, include:

[0100] Silica: 63%, Epoxy Resin E-44: 18%, Curing Agent Polyetheramine: 17.1%, Thickener Fumed Silica: 1.5%, Carbon Black: 0.2%, Accelerator N,N-Dimethylbenzylamine: 0.2%;

[0101] The preparation steps of the bottom filler in this comparative example are the same as in Example 1.

[0102] The underfill adhesives provided in Examples 1-6 and Comparative Examples 1-6 were tested, and the specific test procedures are as follows:

[0103] 1. Test method for dispensing stability: The test was conducted using a dispensing machine (Musashi Smart 350) with a dispensing head inner diameter of 100μm and a pressure of 0.14MPa. 106 dots were used as a group, and 15 groups were dispensed. The CPK was then calculated to measure the stability of the dispensing process. The formula for calculating CPK is:

[0104] ;

[0105] Where USL is the upper limit of the specification, representing the maximum value allowed by the preset requirements; LSL is the lower limit of the specification, representing the minimum value allowed by the preset requirements; μ is the process mean; σ is the process standard deviation, which measures the data volatility.

[0106] 2. Yield stress test: In viscoelastic materials, shear stress is generated the instant the material is subjected to shear force. However, if the shear force is too small, elastic deformation will occur. As the shear force increases, the material produces irreversible deformation. This is because the sample flows, and the shear stress changes suddenly, forming a curve with a gentle slope. The instant the flow occurs is the yield stress point of the material. The test temperature of the rheometer is 24℃, and the shear rate increases from 0.005 (1 / s) to 0.6 (1 / s).

[0107] 3. Viscosity test method: Adjust the circulating cooling water of the viscometer to 25℃, place the adhesive in the sleeve of the viscometer, install it in the detection position of the viscometer, insert the temperature measuring thermocouple, adjust the speed of the viscometer to 20 rpm, and read the viscosity value after 4 minutes.

[0108] 4. Thixotropic (TI) test method: Same as viscosity test method, read the viscosity value at 5 rpm and divide it by the viscosity value at 50 rpm, and record it as the TI value.

[0109] The test results are shown in Table 1 below:

[0110] Table 1 Test Results

[0111]

[0112] As can be seen from the table above:

[0113] (1) No thickener was added in Comparative Example 1 and Comparative Example 2. The yield stress of the prepared bottom filler was low, the dispensing stability was poor, and the dispensing amount was difficult to control.

[0114] (2) The amount of modified polyurea compound thickener added in Comparative Example 3 was too low. Compared with Comparative Example 1, the performance of the underfill adhesive did not change significantly. However, the amount of modified polyurea compound thickener added in Comparative Example 4 was too high. Although it could significantly improve the yield stress and dispensing stability of the underfill adhesive, its thixotropic ability was too strong. This would seriously affect the capillary action of the underfill adhesive, causing its flow to slow down significantly when filling the gap, thus failing to fill the gap and affecting the reliability of chip packaging.

[0115] (3) In Comparative Example 5, rosin glue thickener MX-1518 was used, and in Comparative Example 6, fumed silica was used as thickener. Under the same addition ratio, although the bottom filler glue in Comparative Example 5 can improve the yield stress and dispensing stability, its thixotropic ability increases significantly, which makes the fluidity of the glue worse and thus affects the reliability of chip packaging. In Comparative Example 6, the yield stress and dispensing of the bottom filler glue are significantly improved, but its viscosity and thixotropic ability also increase too fast, which leads to poor fluidity of the glue and is not conducive to filling gaps.

[0116] (4) Compared with Comparative Example 1, the modified polyurea compound thickener added in Example 1 significantly improved the yield stress and dispensing stability of the prepared underfill adhesive (e.g., Figure 1 As shown in the figure, it can meet the chip packaging requirements; from the experimental data of Examples 1-6, it can be seen that within a certain range, as the proportion of thickener added increases, the yield stress and dispensing stability gradually increase, and the gap filling requirements can be met.

[0117] In summary, the underfill adhesive prepared using the formulation ratio provided by this invention has good yield stress and dispensing stability, and can precisely control the dispensing amount, so that it can fill the gap between the chip and the substrate in one go, thereby improving chip packaging efficiency and reliability.

[0118] Finally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises 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.

[0119] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0120] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A dispensing-stabilized underfill adhesive, characterized in that, The bottom filler adhesive is composed of the following components by weight percentage: 60%-67% silica, 17%-21% epoxy resin, 14%-18% curing agent, 0.5%-2.5% thickener, 0.1%-0.3% accelerator, and 0.1%-0.3% carbon black; wherein the main component of the thickener is a modified polyurea compound. The thickener is CO-627; The epoxy resin is either bisphenol A type epoxy resin or bisphenol F type epoxy resin.

2. The dispensing-stabilized underfill adhesive according to claim 1, characterized in that, The silica has a mass percentage of 63%, and the epoxy resin has a mass percentage of 17%-19%.

3. The dispensing-stabilized underfill adhesive according to claim 1, characterized in that, The curing agent has a mass percentage of 16% to 18%, the accelerator has a mass percentage of 0.2%, and the carbon black has a mass percentage of 0.2%.

4. The dispensing-stabilized underfill adhesive according to any one of claims 1-3, characterized in that, The curing agent is an amine curing agent, which includes at least one of triethylenetetramine, polyetheramine, and m-phenylenediamine.

5. The dispensing-stabilized underfill adhesive according to any one of claims 1-3, characterized in that, The accelerator includes at least one of amine accelerators and imidazole accelerators.

6. The dispensing-stabilized underfill adhesive according to claim 5, characterized in that, The amine accelerator includes N,N-dimethylbenzylamine; the imidazole accelerator includes 1-cyanoethyl-2-ethyl-4-methylimidazole.

7. A method for preparing a dispensing-stabilized underfill adhesive, characterized in that, The preparation method includes: Weigh each component of the raw material according to the mass percentage of the dispensing stabilized bottom filler according to any one of claims 1-6, and place them in a mixing cup to obtain the first slurry; The first slurry is stirred by a first centrifugal mixer to obtain a uniformly mixed second slurry; the operating parameters of the first centrifugal mixer include: stirring time of 115-220s, rotation of 2650r / min, and revolution of 2100r / min. The second slurry is transferred to a three-roll mill for dispersion treatment to obtain a uniformly dispersed third slurry; the operating parameters of the three-roll mill include: feed gap of 10-20μm and discharge gap of 2-6μm; The third slurry is vacuum degassed using a second centrifugal mixer to obtain a bottom filling adhesive. The operating parameters of the second centrifugal mixer include: mixing time of 70-100s, rotation of 1850r / min, and revolution of 1500r / min.

8. A chip packaging structure, comprising a substrate, a chip disposed on the substrate, and a plurality of spaced-apart 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, The adhesive of the dispensing stabilized underfill adhesive according to any one of claims 1-6 is placed at the edge of the substrate, so that the adhesive of the underfill adhesive flows from one end of the gap to the other end of the gap through capillary action to fill the gap; The adhesive solution of the bottom filler is cured; After curing, the chip packaging structure is obtained.

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