A high-fluidity bottom filling glue, preparation method thereof and flip chip

Abstract

The present invention provides a high-fluidity bottom filler, a preparation method thereof and a flip chip, wherein the bottom filler comprises the following components by mass percentage: 56% to 66% of modified silica, 19% to 25% of epoxy resin, 15% to 18% of curing agent, 0.1% to 0.2% of carbon black, and 0.2% to 0.4% of defoaming agent; wherein the epoxy resin is composed of bisphenol F epoxy resin and bisphenol A epoxy resin; silica is modified to prepare modified silica as a filling material to enhance the dispersibility and wettability of the modified silica in the matrix material, thereby improving the fluidity of the bottom filler; the defoaming agent is used to avoid the generation of voids and bubbles in the chip packaging process, thereby further improving the bonding performance and thermal stability of the bottom filler. The bottom filler prepared by the present invention through a specific formula ratio has excellent fluidity, can avoid the generation of flow marks, voids and other problems when filling the gap, and improves the packaging efficiency and packaging yield of the chip.

Description

Technical Field

[0001] The invention belongs to the technical field of chip packaging, and in particular relates to a bottom filling adhesive with high fluidity, a preparation method thereof and a flip chip. Background Art

[0002] Underfill is a material suitable for flip chip underfill technology. It usually uses the principle of capillary action to penetrate into the gap between the chip and the substrate, and then gradually solidifies and fills the gap between the chip and the substrate through thermal curing to protect the high-density solder bumps between the chip and the substrate and the chip. However, in the chip packaging process, the fluidity of the underfill directly affects the quality and production efficiency of chip packaging. Underfill with good fluidity can be evenly filled into every gap and void between the chip and the substrate, which can avoid the appearance of voids or unfilled areas. This can not only improve the mechanical strength and durability of the chip, but also prevent external dust, moisture and other contaminants from entering the chip, affecting the performance and life of the chip. Therefore, improving the fluidity of the underfill to adapt to complex assembly environments and strict reliability requirements is crucial to ensuring chip assembly quality and reliability.

[0003] That is, how to provide a high-fluidity bottom filling glue, improve the fluidity of the bottom filling glue by adding modified silica and defoaming agent, avoid the generation of bubbles during the filling process, and then improve the chip packaging yield and packaging efficiency, is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0004] The object of the present invention is to provide a bottom filling glue with high fluidity, a preparation method thereof and a flip chip, so as to solve at least one of the above technical problems.

[0005] To achieve the above-mentioned purpose, the first aspect of the present invention provides a high-fluidity bottom filling glue, which includes the following components in mass percentage: 56% to 66% modified silica, 19% to 25% epoxy resin, 15% to 18% curing agent, 0.1% to 0.2% carbon black, and 0.2% to 0.4% defoaming agent; wherein the epoxy resin is composed of bisphenol F epoxy resin and bisphenol A epoxy resin.

[0006] In the first aspect, the modified silica is prepared by: preparing a mixed solution of deionized water and ethanol; adding the mixed solution to silica to obtain a first mixture; adjusting the pH value of the first mixture to 4 by glacial acetic acid to obtain a second mixture; ultrasonically dispersing the second mixture for 15 minutes to obtain a third mixture; adding a silane coupling agent to the third mixture and ultrasonically dispersing it for 5 minutes to obtain a fourth mixture, wherein the amount of the silane coupling agent added is 3-6% of the mass of the silica; placing the fourth mixture at 100°C for reaction for 2 hours to obtain a reactant; and filtering and drying the reactant to obtain modified silica.

[0007] In the first aspect, the silicon dioxide is spherical silicon dioxide; the average particle size of the spherical silicon dioxide is 1 to 5 μm.

[0008] In the first aspect, the curing agent is an amine curing agent.

[0009] In the first aspect, the amine curing agent includes at least one of diethylaminotoluenediamine, methylcyclohexanediamine and a modified aromatic amine curing agent.

[0010] In the first aspect, the defoaming agent is a polyether defoaming agent.

[0011] The second aspect of the present invention provides a method for preparing the high-flowability bottom filling glue described in the first aspect, the preparation method comprising: preparing modified silica; adding each component into a stirring cup according to their respective mass percentages, and mixing them evenly by a first centrifugal stirrer to obtain a first slurry, wherein the mass percentages of the components specifically include: 56% to 66% of the modified silica, 19% to 25% of the epoxy resin, 15% to 18% of the curing agent, 0.1% to 0.2% of the carbon black, and 0.2% to 0.4% of the defoaming agent; wherein the epoxy resin is composed of bisphenol F epoxy resin and bisphenol A epoxy resin; transferring the first slurry to a three-roll grinder for dispersion treatment to obtain a uniformly dispersed second slurry; and vacuum degassing the second slurry by a second centrifugal stirrer to obtain a bottom filling glue.

[0012] In the second aspect, the preparation method of the modified silica includes: preparing a mixed solution of deionized water and ethanol; adding the mixed solution to silica to obtain a first mixture; adjusting the pH value of the first mixture to 4 by glacial acetic acid to obtain a second mixture; ultrasonically dispersing the second mixture for 15 minutes to obtain a third mixture; adding a silane coupling agent to the third mixture and ultrasonically dispersing it for 5 minutes to obtain a fourth mixture, wherein the amount of the silane coupling agent added is 3-6% of the mass of the silica; placing the fourth mixture at 100°C for reaction for 2 hours to obtain a reactant; and filtering and drying the reactant to obtain modified silica.

[0013] In the second aspect, the working parameters of the first centrifugal mixer include: stirring time of 95 to 110 s, rotation of 1050 r / min, and revolution of 1350 r / min; the working parameters of the three-roll grinder include: feeding gap of 20 to 35 μm, and discharging gap of 5 to 15 μm; the working parameters of the second centrifugal mixer include: stirring time of 65 to 90 s, rotation of 1050 r / min, and revolution of 1350 r / min.

[0014] A third aspect of the present invention provides a flip chip having a packaging structure, wherein the packaging structure includes a material formed by curing the bottom filling glue described in the first aspect.

[0015] Beneficial Effects

[0016] The present invention provides a high-fluidity bottom filler, which includes the following components by mass percentage: 56% to 66% modified silica, 19% to 25% epoxy resin, 15% to 18% curing agent, 0.1% to 0.2% carbon black, and 0.2% to 0.4% defoaming agent; epoxy resin is used as a matrix material to provide the bottom filler with basic bonding properties and mechanical properties; silica is modified to prepare modified silica as a filling material to enhance the dispersibility and wettability of the modified silica in the matrix material, thereby improving the fluidity of the bottom filler; the glue of the bottom filler is cured by adding a curing agent to form a chip package, and a defoaming agent is added to avoid the generation of voids and bubbles in the chip packaging process, thereby further improving the bonding properties and thermal stability of the bottom filler. The bottom filler prepared by the present invention through a specific formula ratio has excellent fluidity, and when filling the gap between the chip and the substrate, it can avoid the generation of flow marks, voids and other problems, thereby improving the chip packaging efficiency and packaging yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. 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 creative work.

[0018] Figure 1 A flow chart of a method for preparing a high-fluidity bottom filling adhesive provided by the present invention;

[0019] Figure 2 A schematic diagram of the generation of voids in Comparative Example 2 of the present invention;

[0020] Figure 3 It is a schematic diagram of flow marks generated in Comparative Example 3 of the present invention;

[0021] Figure 4 It is a schematic diagram of a case without voids in Example 1 of the present invention;

[0022] Figure 5 Schematic diagram of no flow marks in Example 3 of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be described in detail below in conjunction with specific implementations 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 implementations and examples are used to illustrate the present invention, rather than to limit the present invention.

[0024] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0025] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or obtained by existing methods.

[0026] The present invention provides a high-fluidity bottom filling glue, which comprises the following components in mass percentage: 56% to 66% of modified silicon dioxide, 19% to 25% of epoxy resin, 15% to 18% of curing agent, 0.1% to 0.2% of carbon black, and 0.2% to 0.4% of defoaming agent; wherein the epoxy resin is composed of bisphenol F epoxy resin and bisphenol A epoxy resin.

[0027] Specifically, the present invention provides a high-fluidity bottom filler, which includes the following components by mass percentage: modified silica 56% to 66%, epoxy resin 19% to 25%, curing agent 15% to 18%, carbon black 0.1% to 0.2%, and defoaming agent 0.2% to 0.4%; epoxy resin is used as the matrix material to provide the basic bonding performance and mechanical properties of the bottom filler; silica is modified to prepare modified silica as a filling material to enhance the dispersibility and wettability of the modified silica in the matrix material, thereby improving the fluidity of the bottom filler; the glue of the bottom filler is cured by adding a curing agent to form a chip package, and a defoaming agent is added to reduce the generation of voids and bubbles in the chip packaging process, further improving the bonding performance and thermal stability of the bottom filler. The bottom filler prepared by the present invention through a specific formula ratio has excellent fluidity. When filling the gap between the chip and the substrate, it can avoid the generation of flow marks, voids and other problems, thereby improving the chip packaging efficiency and packaging yield.

[0028] In some possible embodiments, the modified silica is prepared by: preparing a mixed solution of deionized water and ethanol; adding the mixed solution to silica to obtain a first mixture; adjusting the pH value of the first mixture to 4 by glacial acetic acid to obtain a second mixture; ultrasonically dispersing the second mixture for 15 minutes to obtain a third mixture; adding a silane coupling agent to the third mixture and ultrasonically dispersing it for 5 minutes to obtain a fourth mixture, wherein the amount of the silane coupling agent added is 3-6% of the mass of the silica; placing the fourth mixture at 100°C for reaction for 2 hours to obtain a reactant; and filtering and drying the reactant to obtain modified silica.

[0029] This is because the dispersibility of silicon dioxide directly affects the fluidity of the bottom filling glue. Poor dispersion can easily lead to glue agglomeration, resulting in flow marks, voids and other problems during the filling process. In this embodiment, the commercially available silicon dioxide is first pretreated to improve the activity of silicon dioxide and form hydroxyl groups on the surface of silicon dioxide; then a silane coupling agent is added to modify the silicon dioxide, and after the reaction is completed, it is filtered and dried to obtain modified silicon dioxide. As the amount of silane coupling agent increases, the hydroxyl groups on the surface of silica and the silanol groups (Si-OH) generated by the hydrolysis of the silane coupling agent reduce the number of hydroxyl groups on the surface of silica. After modification, most of the hydroxyl groups on the surface of silica are replaced by the silane coupling agent, the polarity is weakened, the surface energy is reduced, the oil absorption capacity is weak, the oil absorption value is reduced, and the activation index is increased; when the silane coupling agent is excessive, the reverse reaction trend of the silane coupling agent hydrolyzing under high concentration conditions is strengthened, so that the Si-OH generated by the hydrolysis reaction is reduced, thereby increasing the hydroxyl groups on the surface of the modified silica, making the modified silica prone to agglomeration, and then the activity index of the modified silica is reduced and the oil absorption value is increased, affecting the dispersibility of the modified silica in the bottom filling glue. In addition, the application needs to control the addition amount of the silane coupling agent to 3-6% of the mass of silica to improve the dispersibility of the modified silica in the epoxy resin. The silane coupling agent can be selected as γ-aminopropyltriethoxysilane.

[0030] In some possible embodiments, the silicon dioxide is spherical silicon dioxide; the average particle size of the spherical silicon dioxide is 1 to 5 μm.

[0031] Those skilled in the art will appreciate that selecting spherical silica for modification can improve the dispersibility and wettability of silica, thereby improving the fluidity of the bottom filling glue.

[0032] In some possible embodiments, the curing agent is an amine curing agent.

[0033] In some possible embodiments, the amine curing agent includes at least one of diethylaminotoluenediamine, methylcyclohexanediamine and modified aromatic amine curing agents.

[0034] Adding a curing agent to the bottom fill glue can shorten the curing time of the bottom fill glue and improve the packaging efficiency of the bottom fill glue.

[0035] In some possible embodiments, the defoaming agent is a polyether defoaming agent.

[0036] The defoaming agent can be a polyether defoaming agent, which has good compatibility with epoxy resin and can reduce bubbles generated when the raw materials of the bottom filling glue are mixed. After the bottom filling glue is cured and formed, no voids will be generated at the contact part with the chip, thereby improving the chip packaging yield.

[0037] Based on a general inventive concept, see Figure 1 The second aspect of the present invention provides a method for preparing the high-flow bottom filling glue as described in the first aspect, the preparation method comprising:

[0038] S1. preparing modified silicon dioxide;

[0039] S2, adding each component according to their respective mass percentages into a stirring cup, and mixing them evenly by a first centrifugal stirrer to obtain a first slurry, wherein the mass percentages of the components specifically include: 56% to 66% of the modified silicon dioxide, 19% to 25% of the epoxy resin, 15% to 18% of the curing agent, 0.1% to 0.2% of the carbon black, and 0.2% to 0.4% of the defoaming agent; wherein the epoxy resin is composed of bisphenol F epoxy resin and bisphenol A epoxy resin;

[0040] S3, transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry;

[0041] S4. Vacuum degassing the second slurry using a second centrifugal mixer to obtain a bottom filling adhesive.

[0042] In combination with the second aspect of the present application, the preparation method of the modified silica includes: preparing a mixed solution of deionized water and ethanol; adding the mixed solution to silica to obtain a first mixture; adjusting the pH value of the first mixture to 4 by glacial acetic acid to obtain a second mixture; ultrasonically dispersing the second mixture for 15 minutes to obtain a third mixture; adding a silane coupling agent to the third mixture and ultrasonically dispersing it for 5 minutes to obtain a fourth mixture, wherein the amount of the silane coupling agent added is 3-6% of the mass of the silica; placing the fourth mixture at 100°C for reaction for 2 hours to obtain a reactant; and filtering and drying the reactant to obtain modified silica.

[0043] In combination with the second aspect of the present application, the working parameters of the first centrifugal mixer include: stirring time of 95 to 110 s, rotation of 1050 r / min, and revolution of 1350 r / min; the working parameters of the three-roll grinder include: feeding gap of 20 to 35 μm, and discharging gap of 5 to 15 μm; the working parameters of the second centrifugal mixer include: stirring time of 65 to 90 s, rotation of 1050 r / min, and revolution of 1350 r / min.

[0044] Based on a general inventive concept, the third aspect of the present invention provides a flip chip, wherein the flip chip has a packaging structure, and the packaging structure includes a material formed by curing the bottom filling glue described in the first aspect.

[0045] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0046] Example 1

[0047] In terms of mass percentage, the raw materials of the bottom filler include:

[0048] Modified silica: 57%, epoxy resin YLSE-162L: 12.7%, epoxy resin NPEL-128: 12%, curing agent VT5327: 18%; carbon black: 0.1%; defoaming agent HS-703: 0.2%;

[0049] The specific steps of preparing the above bottom filling are as follows:

[0050] (1) Preparing modified silica; weighing 57 g of silica into a beaker, adding a mixed solution of deionized water and ethanol, adjusting the pH value of the solution to 4 with glacial acetic acid, ultrasonically dispersing the solid-liquid mixture to fully mix the silica and the solution, the ultrasonic time is 15 min, adding a silane coupling agent with a mass fraction of 3% of the silica using a pipette, and continuing the ultrasonic treatment for 5 min; using a constant temperature magnetic stirrer to perform a modification reaction on the solid-liquid mixture after ultrasonication, the temperature is 100°C and the reaction time is 2 h; after the reaction is completed, the silica is filtered and dried to obtain modified silica;

[0051] (2) Weighing each component according to the mass percentage of each raw material of the above-mentioned bottom filling glue, and adding them into a stirring cup in sequence, and mixing them evenly by a first centrifugal stirrer to obtain a first slurry; wherein the stirring time of the first centrifugal stirrer is set to 95 seconds, the rotation speed is 1050 r / min, and the revolution speed is 1350 r / min;

[0052] (3) transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; wherein the feed gap of the three rollers in the three-roll mill is 20 μm, and the discharge gap is 5 μm;

[0053] (4) vacuum degassing the second slurry by a second centrifugal mixer to obtain a bottom filling glue; wherein the second centrifugal mixer is set to have a stirring time of 65 seconds, a rotation speed of 1050 r / min, and a revolution speed of 1350 r / min.

[0054] Example 2

[0055] In terms of mass percentage, the raw materials of the bottom filler include:

[0056] Modified silica: 60%, epoxy resin YLSE-162L: 10.7%, epoxy resin NPEL-128: 12%, curing agent diethyltoluenediamine: 17%; carbon black: 0.1%; defoaming agent DF4226: 0.2%;

[0057] The specific steps of preparing the above bottom filling are as follows:

[0058] (1) Preparing modified silica; weighing 60 g of silica into a beaker, adding a mixed solution of deionized water and ethanol, adjusting the pH value of the solution to 4 with glacial acetic acid, ultrasonically dispersing the solid-liquid mixture to fully mix the silica and the solution, the ultrasonic time is 15 min, adding a silane coupling agent with a mass fraction of 4% of the silica using a pipette, and continuing the ultrasonic treatment for 5 min; using a constant temperature magnetic stirrer to perform a modification reaction on the solid-liquid mixture after ultrasonication, the temperature is 100°C and the reaction time is 2 h; after the reaction is completed, the silica is filtered and dried to obtain modified silica;

[0059] (2) Weighing each component according to the mass percentage of each raw material of the above-mentioned bottom filling glue, and adding them into a stirring cup in sequence, and mixing them evenly by a first centrifugal stirrer to obtain a first slurry; wherein the stirring time of the first centrifugal stirrer is set to 100 seconds, the rotation speed is 1050 r / min, and the revolution speed is 1350 r / min;

[0060] (3) transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; wherein the feed gap of the three rollers in the three-roll mill is 25 μm, and the discharge gap is 15 μm;

[0061] (4) vacuum degassing the second slurry by a second centrifugal mixer to obtain a bottom filling glue; wherein the second centrifugal mixer is set to have a stirring time of 75 seconds, a rotation speed of 1050 r / min, and a revolution speed of 1350 r / min.

[0062] Example 3

[0063] In terms of mass percentage, the raw materials of the bottom filler include:

[0064] Modified silica: 62%, epoxy resin YLSE-162L: 10.7%, epoxy resin NPEL-128: 9%, curing agent diethyltoluenediamine: 18%; carbon black: 0.1%; defoaming agent HS-703: 0.2%;

[0065] The specific steps of preparing the above bottom filling are as follows:

[0066] (1) Preparing modified silica; weighing 62 g of silica into a beaker, adding a mixed solution of deionized water and ethanol, adjusting the pH value of the solution to 4 with glacial acetic acid, ultrasonically dispersing the solid-liquid mixture to fully mix the silica and the solution, the ultrasonic time is 15 min, adding a silane coupling agent with a mass fraction of 5% of the silica using a pipette, and continuing the ultrasonic treatment for 5 min; using a constant temperature magnetic stirrer to perform a modification reaction on the solid-liquid mixture after ultrasonication, the temperature is 100°C and the reaction time is 2 h; after the reaction is completed, the silica is filtered and dried to obtain modified silica;

[0067] (2) Weighing each component according to the mass percentage of each raw material of the above-mentioned bottom filling glue, and adding them into a stirring cup in sequence, and mixing them evenly by a first centrifugal stirrer to obtain a first slurry; wherein the stirring time of the first centrifugal stirrer is set to 110 seconds, the rotation speed is 1050 r / min, and the revolution speed is 1350 r / min;

[0068] (3) transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; wherein the feed gap of the three rollers in the three-roll mill is 35 μm, and the discharge gap is 10 μm;

[0069] (4) vacuum degassing the second slurry by a second centrifugal mixer to obtain a bottom filling glue; wherein the second centrifugal mixer is set to have a stirring time of 85 seconds, a rotation speed of 1050 r / min, and a revolution speed of 1350 r / min.

[0070] Example 4

[0071] In terms of mass percentage, the raw materials of the bottom filler include:

[0072] Modified silica: 65%, epoxy resin YLSE-162L: 9.7%, epoxy resin NPEL-128: 10%, curing agent methylcyclohexanediamine: 15%; carbon black: 0.1%; defoaming agent HS-703: 0.2%;

[0073] The specific steps of preparing the above bottom filling are as follows:

[0074] (1) Preparing modified silica; weighing 65 g of silica into a beaker, adding a mixed solution of deionized water and ethanol, adjusting the pH value of the solution to 4 with glacial acetic acid, ultrasonically dispersing the solid-liquid mixture to fully mix the silica and the solution, the ultrasonic time is 15 min, adding a silane coupling agent with a mass fraction of 6% of the silica using a pipette, and continuing the ultrasonic treatment for 5 min; using a constant temperature magnetic stirrer to perform a modification reaction on the solid-liquid mixture after ultrasonication, the temperature is 100°C and the reaction time is 2 h; after the reaction is completed, the silica is filtered and dried to obtain modified silica;

[0075] (2) Weighing each component according to the mass percentage of each raw material of the above-mentioned bottom filling glue, and adding them into a stirring cup in sequence, and mixing them evenly by a first centrifugal stirrer to obtain a first slurry; wherein the stirring time of the first centrifugal stirrer is set to 110 seconds, the rotation speed is 1050 r / min, and the revolution speed is 1350 r / min;

[0076] (3) transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; wherein the feed gap of the three rollers in the three-roll mill is 35 μm, and the discharge gap is 10 μm;

[0077] (4) vacuum degassing the second slurry by a second centrifugal mixer to obtain a bottom filling glue; wherein the second centrifugal mixer is set to have a stirring time of 90 seconds, a rotation speed of 1050 r / min, and a revolution speed of 1350 r / min.

[0078] Comparative Example 1

[0079] In terms of mass percentage, the raw materials of the bottom filler include:

[0080] Silicon dioxide: 60%, epoxy resin YLSE-162L: 10.7%, epoxy resin NPEL-128: 12%, curing agent diethyltoluenediamine: 17%; carbon black: 0.1%; defoaming agent HS-703: 0.2%;

[0081] The specific steps of preparing the above bottom filling are as follows:

[0082] (1) Weighing each component according to the mass percentage of each raw material of the above-mentioned bottom filling glue, and adding them into a stirring cup in sequence, and mixing them evenly by a first centrifugal stirrer to obtain a first slurry; wherein the stirring time of the first centrifugal stirrer is set to 110 seconds, the rotation speed is 1050 r / min, and the revolution speed is 1350 r / min;

[0083] (2) transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; wherein the feed gap of the three rollers in the three-roll mill is 35 μm, and the discharge gap is 10 μm;

[0084] (3) vacuum degassing the second slurry by a second centrifugal mixer to obtain a bottom filling glue; wherein the second centrifugal mixer is set to have a stirring time of 90 seconds, a rotation speed of 1050 r / min, and a revolution speed of 1350 r / min.

[0085] Comparative Example 2

[0086] In terms of mass percentage, the raw materials of the bottom filler include:

[0087] Modified silica: 60%, epoxy resin YLSE-162L: 10.7%, epoxy resin NPEL-128: 12%, curing agent diethyltoluenediamine: 17%; carbon black: 0.1%; defoaming agent HS-703: 0.2%;

[0088] The specific steps of preparing the above bottom filling are as follows:

[0089] (1) Preparing modified silica; weighing 60 g of silica into a beaker, adding a mixed solution of deionized water and ethanol, adjusting the pH value of the solution to 4 with glacial acetic acid, ultrasonically dispersing the solid-liquid mixture to fully mix the silica and the solution, the ultrasonic time is 15 min, adding a silane coupling agent with a mass fraction of 2% of the silica using a pipette, and continuing the ultrasonic treatment for 5 min; using a constant temperature magnetic stirrer to perform a modification reaction on the solid-liquid mixture after ultrasonication, the temperature is 100°C and the reaction time is 2 h; after the reaction is completed, the silica is filtered and dried to obtain modified silica;

[0090] (2) Weighing each component according to the mass percentage of each raw material of the above-mentioned bottom filling glue, and adding them into a stirring cup in sequence, and mixing them evenly by a first centrifugal stirrer to obtain a first slurry; wherein the stirring time of the first centrifugal stirrer is set to 110 seconds, the rotation speed is 1050 r / min, and the revolution speed is 1350 r / min;

[0091] (3) transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; wherein the feed gap of the three rollers in the three-roll mill is 35 μm, and the discharge gap is 10 μm;

[0092] (4) vacuum degassing the second slurry by a second centrifugal mixer to obtain a bottom filling glue; wherein the second centrifugal mixer is set to have a stirring time of 90 seconds, a rotation speed of 1050 r / min, and a revolution speed of 1350 r / min.

[0093] Comparative Example 3

[0094] In terms of mass percentage, the raw materials of the bottom filler include:

[0095] Modified silica: 60%, epoxy resin YLSE-162L: 10.7%, epoxy resin NPEL-128: 12%, curing agent diethyltoluenediamine: 17%; carbon black: 0.1%; defoaming agent HS-703: 0.2%;

[0096] The specific steps of preparing the above bottom filling are as follows:

[0097] (1) Preparing modified silica; weighing 60 g of silica into a beaker, adding a mixed solution of deionized water and ethanol, adjusting the pH value of the solution to 4 with glacial acetic acid, ultrasonically dispersing the solid-liquid mixture to fully mix the silica and the solution, the ultrasonic time is 15 min, adding a silane coupling agent with a mass fraction of 7% of the silica using a pipette, and continuing the ultrasonic treatment for 5 min; using a constant temperature magnetic stirrer to perform a modification reaction on the solid-liquid mixture after ultrasonication, the temperature is 100°C and the reaction time is 2 h; after the reaction is completed, the silica is filtered and dried to obtain modified silica;

[0098] (2) Weighing each component according to the mass percentage of each raw material of the above-mentioned bottom filling glue, and adding them into a stirring cup in sequence, and mixing them evenly by a first centrifugal stirrer to obtain a first slurry; wherein the stirring time of the first centrifugal stirrer is set to 110 seconds, the rotation speed is 1050 r / min, and the revolution speed is 1350 r / min;

[0099] (3) transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; wherein the feed gap of the three rollers in the three-roll mill is 35 μm, and the discharge gap is 10 μm;

[0100] (4) vacuum degassing the second slurry by a second centrifugal mixer to obtain a bottom filling glue; wherein the second centrifugal mixer is set to have a stirring time of 90 seconds, a rotation speed of 1050 r / min, and a revolution speed of 1350 r / min.

[0101] Comparative Example 4

[0102] In terms of mass percentage, the raw materials of the bottom filler include:

[0103] Modified silica: 55%, epoxy resin YLSE-162L: 13%, epoxy resin NPEL-128: 13%, curing agent methylcyclohexanediamine: 18.7%; carbon black: 0.1%; defoaming agent DF4226: 0.2%;

[0104] The specific steps of preparing the above bottom filling are as follows:

[0105] (1) Preparing modified silica; weighing 55 g of silica into a beaker, adding a mixed solution of deionized water and ethanol, adjusting the pH value of the solution to 4 with glacial acetic acid, ultrasonically dispersing the solid-liquid mixture to fully mix the silica and the solution, the ultrasonic time is 15 min, adding a silane coupling agent with a mass fraction of 3% of the silica using a pipette, and continuing the ultrasonic treatment for 5 min; using a constant temperature magnetic stirrer to perform a modification reaction on the solid-liquid mixture after ultrasonication, the temperature is 100°C and the reaction time is 2 h; after the reaction is completed, the silica is filtered and dried to obtain modified silica;

[0106] (2) Weighing each component according to the mass percentage of each raw material of the above-mentioned bottom filling glue, and adding them into a stirring cup in sequence, and mixing them evenly by a first centrifugal stirrer to obtain a first slurry; wherein the stirring time of the first centrifugal stirrer is set to 110 seconds, the rotation speed is 1050 r / min, and the revolution speed is 1350 r / min;

[0107] (3) transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; wherein the feed gap of the three rollers in the three-roll mill is 35 μm, and the discharge gap is 10 μm;

[0108] (4) vacuum degassing the second slurry by a second centrifugal mixer to obtain a bottom filling glue; wherein the second centrifugal mixer is set to have a stirring time of 90 seconds, a rotation speed of 1050 r / min, and a revolution speed of 1350 r / min.

[0109] Comparative Example 5

[0110] In terms of mass percentage, the raw materials of the bottom filler include:

[0111] Modified silica: 67%, epoxy resin YLSE-162L: 9%, epoxy resin NPEL-128: 9%, curing agent VT5327: 14.7%; carbon black: 0.1%; defoaming agent DF4226: 0.2%;

[0112] The specific steps of preparing the above bottom filling are as follows:

[0113] (1) Preparing modified silica; weighing 67 g of silica into a beaker, adding a mixed solution of deionized water and ethanol, adjusting the pH value of the solution to 4 with glacial acetic acid, ultrasonically dispersing the solid-liquid mixture to fully mix the silica and the solution, the ultrasonic time is 15 min, adding a silane coupling agent with a mass fraction of 4% of the silica using a pipette, and continuing the ultrasonic treatment for 5 min; using a constant temperature magnetic stirrer to perform a modification reaction on the solid-liquid mixture after ultrasonication, the temperature is 100°C and the reaction time is 2 h; after the reaction is completed, the silica is filtered and dried to obtain modified silica;

[0114] (2) Weighing each component according to the mass percentage of each raw material of the above-mentioned bottom filling glue, and adding them into a stirring cup in sequence, and mixing them evenly by a first centrifugal stirrer to obtain a first slurry; wherein the stirring time of the first centrifugal stirrer is set to 110 seconds, the rotation speed is 1050 r / min, and the revolution speed is 1350 r / min;

[0115] (3) transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; wherein the feed gap of the three rollers in the three-roll mill is 35 μm, and the discharge gap is 10 μm;

[0116] (4) vacuum degassing the second slurry by a second centrifugal mixer to obtain a bottom filling glue; wherein the second centrifugal mixer is set to have a stirring time of 90 seconds, a rotation speed of 1050 r / min, and a revolution speed of 1350 r / min.

[0117] The bottom filling glue provided in Examples 1-4 and Comparative Examples 1-5 was subjected to a viscosity test and a fluidity test, and the bonding between the bottom silicon wafer and the substrate carrier was observed under an ultrasonic scanning microscope, and the modified silicon dioxide was subjected to an activation index test and an oil absorption value test. The specific test process is as follows:

[0118] 1. Viscosity test: Use a digital display rotational viscometer for measurement; Test conditions: Select 14# rotor, the speed is 50r / min, and the measurement is carried out at 25℃;

[0119] 2. Test method for fluidity: Place a 15×25 mm silicon wafer with copper pillars on the PCB and fix it. Place it on a 110°C hot plate and preheat it for one minute. Use a dispenser to dispense (40-45) mg of the bottom filler to be tested along the long side of the silicon wafer. Under the action of capillary force, the bottom filler will flow to the bottom of the silicon wafer. Record the time it takes to fill the entire silicon wafer.

[0120] 3. Ultrasonic scanning microscope: The silicon wafer after fluidity test is cured at 165℃ / 2h, and then ultrasonically scanned after curing, with a maximum scanning speed of 600mm / s and a sampling frequency of 500MHz, to detect the bonding between the silicon wafer and the substrate carrier to observe whether there are any defects;

[0121] 4. Activation index test: Weigh a certain mass of sample (modified silica), place it in a beaker containing a certain volume of pure water, and stir it at a certain speed for (1-2) min; after the solution is allowed to stand and become clear, scrape off the material on the surface of the aqueous solution, and filter, dry and weigh the material that has sunk to the bottom of the beaker to obtain the mass of the bottom material. Then calculate the activation index according to the following formula, namely:

[0122] ;

[0123] 5. Oil absorption value test: GB / T 5211.15-2014. The principle of oil absorption value test is to gradually add reagents (such as dioctyl phthalate DOP) to a certain sample, fully stir it into a mass, and no excessive reagent is leached. The oil absorption of the sample is calculated by increasing the mass of the reagent. During the measurement process, the whole process is controlled between (20-25) min, and the whole process is fully stirred. The measurement result is calculated using the mass of the reagent absorbed by 100g sample (modified silica) (in g).

[0124] The test results are shown in Table 1 below:

[0125] Table 1 Test results

[0126]

[0127] From the above table, we can see that:

[0128] (1) Comparative Example 1 uses commercially available silicon dioxide instead of modified silicon dioxide. The bottom filling glue prepared has high viscosity and poor dispersibility. When the glue flows through the area with small spacing between copper pillars, glue accumulation occurs. After curing, voids appear between the bottom filling glue and the chip. Moreover, the epoxy resin and silicon dioxide are delaminated at high temperature, resulting in uneven flow rate and flow marks.

[0129] (2) Comparative Example 2 uses 2% of silane coupling agent to modify silicon dioxide, and Comparative Example 3 uses 7% of silane coupling agent to modify silicon dioxide. Since the addition ratio of the silane coupling agent exceeds the range specified in the present invention, the prepared bottom filling glue has a high viscosity and poor fluidity, and has defects such as flow marks and voids after curing. Figure 2 (Comparative Example 2) and Figure 3 (Comparative Example 3) shown;

[0130] (3) Although the modified silica prepared in Comparative Examples 4 and 5 is qualified, the addition amounts of modified silica, epoxy resin and curing agent in the bottom filling glue are not within the set range, resulting in defects such as flow marks and voids in the bottom filling glue during the molding process;

[0131] (4) The bottom filling glue prepared by Examples 1-5 using the formula ratio provided by the present invention has low viscosity and excellent fluidity, and has no defects such as flow marks and voids during curing, thereby improving the packaging efficiency and packaging yield of the chip.

[0132] 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 series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article, or apparatus.

[0133] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other 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.

[0134] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A high-flow bottom filling glue, characterized in that: The bottom filling glue is composed of the following components by mass percentage: 57% to 65% of modified silicon dioxide, 19% to 25% of epoxy resin, 15% to 18% of curing agent, 0.1% to 0.2% of carbon black, and 0.2% to 0.4% of defoaming agent; wherein the epoxy resin is composed of bisphenol F epoxy resin and bisphenol A epoxy resin; The modified silica is prepared by: preparing a mixed solution of deionized water and ethanol; adding the mixed solution to silica to obtain a first mixture; adjusting the pH value of the first mixture to 4 by glacial acetic acid to obtain a second mixture; ultrasonically dispersing the second mixture for 15 minutes to obtain a third mixture; adding a silane coupling agent to the third mixture and ultrasonically dispersing it for 5 minutes to obtain a fourth mixture, wherein the amount of the silane coupling agent added is 3-6% of the mass of the silica; placing the fourth mixture at 100° C. for reaction for 2 hours to obtain a reactant; suction filtering the reactant and drying it to obtain the modified silica; The curing agent is an amine curing agent; the amine curing agent includes at least one of diethylaminotoluenediamine, methylcyclohexanediamine and modified aromatic amine curing agent.

2. The high-flow bottom filling adhesive according to claim 1, characterized in that: The silicon dioxide is spherical silicon dioxide; the average particle size of the spherical silicon dioxide is 1 to 5 μm.

3. The high-flow bottom filling adhesive according to claim 1, characterized in that: The defoamer is a polyether defoamer.

4. A method for preparing a high-flow bottom filling adhesive as claimed in any one of claims 1 to 3, characterized in that: The preparation method comprises: preparing modified silica; Add each component into a stirring cup according to its respective mass percentage, mix evenly by a first centrifugal stirrer, and obtain a first slurry, wherein the mass percentage of each component specifically includes: 57% to 65% of the modified silicon dioxide, 19% to 25% of the epoxy resin, 15% to 18% of the curing agent, 0.1% to 0.2% of the carbon black, and 0.2% to 0.4% of the defoaming agent; wherein the epoxy resin is composed of bisphenol F epoxy resin and bisphenol A epoxy resin; Transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; The second slurry is vacuum degassed by a second centrifugal mixer to obtain a bottom filling glue; The preparation method of the modified silicon dioxide comprises: preparing a mixed solution of deionized water and ethanol; adding the mixed solution to silicon dioxide to obtain a first mixture; adjusting the pH value of the first mixture to 4 by glacial acetic acid to obtain a second mixture; ultrasonically dispersing the second mixture for 15 minutes to obtain a third mixture; adding a silane coupling agent to the third mixture and ultrasonically dispersing it for 5 minutes to obtain a fourth mixture, wherein the amount of the silane coupling agent added is 3-6% of the mass of the silicon dioxide; placing the fourth mixture at 100° C. for reaction for 2 hours to obtain a reactant; and suction filtering and drying the reactant to obtain the modified silicon dioxide.

5. The method for preparing a high-fluidity bottom filling adhesive according to claim 4, characterized in that: The working parameters of the first centrifugal mixer include: stirring time of 95 to 110 seconds, rotation of 1050 r / min, revolution of 1350 r / min; The working parameters of the three-roller mill include: the feed gap is 20 to 35 μm, the discharge gap is 5 to 15 μm; The working parameters of the second centrifugal mixer include: stirring time of 65 to 90 seconds, rotation of 1050 r / min, and revolution of 1350 r / min.

6. A flip chip, characterized in that: The flip chip has a packaging structure, and the packaging structure includes a material formed by curing the high-fluidity bottom filling glue according to any one of claims 1 to 3.

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