High reliability single-component bottom filling glue, preparation method thereof and flip chip

Abstract

The present invention provides a high-reliability single-component bottom filler, a preparation method thereof and a flip chip, wherein the bottom filler comprises the following components by mass percentage: 50% to 60% spherical silica, 28% to 32% epoxy resin, 13% to 17% modified polyetheramine curing agent, 0.1% to 0.2% carbon black, 0.3% to 0.5% silane coupling agent, and 0.2% to 0.4% adhesion promoter; the epoxy resin is composed of bisphenol A epoxy resin and a first epoxy resin, and the model of the first epoxy resin is NANOPOX®E500 or NANOPOX®E470. The present invention controls the thermal expansion coefficient and storage modulus of the bottom filler by adjusting the ratio between the first epoxy resin, the bisphenol A epoxy resin and the modified polyetheramine curing agent, so as to ensure that the bottom filler is still in close contact with the chip under high and low temperature environments for a long time, thereby improving the reliability of chip packaging.

Description

Technical Field

[0001] The invention belongs to the technical field of chip packaging, and particularly relates to a high-reliability single-component bottom filling glue, a preparation method thereof and a flip chip. Background Art

[0002] With the continuous advancement of technology, chip packaging technology will continue to develop towards higher integration, better heat dissipation performance and higher reliability. However, the thermal expansion coefficients between silicon chips and printed circuit boards are very different, which leads to cracking during temperature cycling and high-temperature storage experiments; high-modulus bottom fill glue can reduce solder joint fatigue damage, but too high a modulus will cause the chip to crack during material curing and shrinkage. The appropriate modulus can better cope with the mismatch between the chip and other devices. Therefore, a low expansion coefficient and low modulus bottom fill glue can well protect the chip and improve chip reliability.

[0003] That is, how to provide a high-reliability one-component bottom filling glue, by adjusting the ratio between bisphenol A epoxy resin, the first epoxy resin and the modified polyether amine curing agent, so that the bottom filling glue has a lower thermal expansion coefficient and modulus, and improves the reliability of chip packaging 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 high-reliability single-component bottom filling glue, a preparation method thereof and a flip chip, so as to solve at least one of the above-mentioned technical problems.

[0005] To achieve the above-mentioned purpose, the first aspect of the present invention provides a high-reliability one-component bottom filling glue, which includes the following components in mass percentage: 50% to 60% spherical silica, 28% to 32% epoxy resin, 13% to 17% modified polyether amine curing agent, 0.1% to 0.2% carbon black, 0.3% to 0.5% silane coupling agent, and 0.2% to 0.4% adhesion promoter; the epoxy resin is composed of bisphenol A epoxy resin and a first epoxy resin, and the model of the first epoxy resin is NANOPOX®E500 or NANOPOX®E470.

[0006] In the first aspect, the mass percentage of the bisphenol A epoxy resin is 15% to 16%, and the mass percentage of the first epoxy resin is 14% to 15%.

[0007] In the first aspect, the type of the bisphenol A epoxy resin includes at least one of E44, DER321, and DER324.

[0008] In the first aspect, the modified polyetheramine curing agent is prepared by the following method: heating and stirring the polyetheramine, after stirring evenly, adding isooctyl acrylate dropwise to the polyetheramine, the molar ratio of the polyetheramine to the isooctyl acrylate being 1:1, and continuing the reaction to obtain the modified polyetheramine curing agent.

[0009] In the first aspect, the structural formula of the modified polyetheramine curing agent is:

[0010] .

[0011] In the first aspect, the particle size of the spherical silica is 0.5 to 5 μm.

[0012] In the first aspect, the adhesion promoter includes Adherant1121.

[0013] A second aspect of the present invention provides a method for preparing the high-reliability single-component underfill adhesive as described in the first aspect, the preparation method comprising:

[0014] S1. Add each component into a stirring cup according to their respective mass percentages, and mix them evenly by a first centrifugal stirrer to obtain a first slurry; the mass percentages of the components specifically include: 50% to 60% spherical silica, 28% to 32% epoxy resin, 13% to 17% modified polyether amine curing agent, 0.1% to 0.2% carbon black, 0.3% to 0.5% silane coupling agent, and 0.2% to 0.4% adhesion promoter;

[0015] S2, transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry;

[0016] S3. Vacuum degassing the second slurry using a second centrifugal mixer to obtain a bottom filling adhesive.

[0017] In the second aspect, the working parameters of the first centrifugal mixer include: stirring time of 50 to 75 s, rotation of 800 r / min, and revolution of 1000 r / min; the working parameters of the three-roll grinder include: feeding gap of 20 to 35 μm, and discharging gap of 10 to 15 μm; the working parameters of the second centrifugal mixer include: vacuum degassing time of 55 to 70 s, rotation of 100 r / min, and revolution of 1000 r / min.

[0018] 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 high-reliability single-component bottom filling adhesive described in the first aspect.

[0019] Beneficial effects:

[0020] The present invention provides a high-reliability one-component bottom filling adhesive, which comprises the following components by mass percentage: 50% to 60% of spherical silica, 28% to 32% of epoxy resin, 13% to 17% of modified polyetheramine curing agent, 0.1% to 0.2% of carbon black, 0.3% to 0.5% of silane coupling agent, and 0.2% to 0.4% of adhesion promoter; the epoxy resin is composed of bisphenol A epoxy resin and a first epoxy resin, and the model of the first epoxy resin is NANOPOX® E500 or NANOP OX®E470; A first epoxy resin containing a small amount of nano-silicon dioxide and a bisphenol A epoxy resin are used as the base resin to provide bonding properties and mechanical properties for the bottom filling glue, and then the micron-sized spherical silica is combined to effectively reduce the thermal expansion coefficient of the bottom filling glue, and a modified polyetheramine curing agent with a branched structure is used to react with the base resin to reduce the modulus of the bottom filling glue, and at the same time, a small amount of silane coupling agent is used to improve the adhesion between the substrate and the chip of the bottom filling glue, thereby improving the reliability of chip packaging. The present invention controls the thermal expansion coefficient and storage modulus of the bottom filling glue by adjusting the ratio between the first epoxy resin, the bisphenol A epoxy resin and the modified polyetheramine curing agent, so as to ensure that the bottom filling glue is still in close contact with the chip under high and low temperature environments for a long time, thereby improving the reliability of chip packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] Figure 1 The present invention is a flowchart of a method for preparing a high-reliability single-component bottom filling adhesive. 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 application provides a high-reliability one-component bottom filling glue, which includes the following components in mass percentage: 50% to 60% spherical silica, 28% to 32% epoxy resin, 13% to 17% modified polyether amine curing agent, 0.1% to 0.2% carbon black, 0.3% to 0.5% silane coupling agent, and 0.2% to 0.4% adhesion promoter; the epoxy resin is composed of bisphenol A epoxy resin and a first epoxy resin, and the model of the first epoxy resin is NANOPOX®E500 or NANOPOX®E470.

[0027] Specifically, the present invention provides a high-reliability one-component bottom filling adhesive, which includes the following components by mass percentage: 50% to 60% spherical silica, 28% to 32% epoxy resin, 13% to 17% modified polyether amine curing agent, 0.1% to 0.2% carbon black, 0.3% to 0.5% silane coupling agent, and 0.2% to 0.4% adhesion promoter; the epoxy resin is composed of bisphenol A epoxy resin and a first epoxy resin, and the model of the first epoxy resin is NANOPOX® E500 or NANOPOX® E500. OPOX®E470; A first epoxy resin containing a small amount of nano-silicon dioxide and a bisphenol A epoxy resin are used as the base resin to provide bonding properties and mechanical properties for the bottom filling glue, and then the micron-sized spherical silica is combined to effectively reduce the thermal expansion coefficient of the bottom filling glue, and a modified polyetheramine curing agent with a branched structure is used to react with the base resin to reduce the modulus of the bottom filling glue, and a small amount of silane coupling agent is used to improve the adhesion between the substrate and the chip of the bottom filling glue, thereby improving the reliability of chip packaging. The present invention controls the thermal expansion coefficient and storage modulus of the bottom filling glue by adjusting the ratio between the first epoxy resin, the bisphenol A epoxy resin and the modified polyetheramine curing agent, so as to ensure that the bottom filling glue is still in close contact with the chip under high and low temperature environments for a long time, thereby improving the reliability of chip packaging.

[0028] In some possible embodiments, the mass percentage of the bisphenol A epoxy resin is 15% to 16%, and the mass percentage of the first epoxy resin is 14% to 15%.

[0029] In some possible embodiments, the type of the bisphenol A epoxy resin includes at least one of E44, DER321, and DER324.

[0030] The first epoxy resins NANOPOX®E500 and NANOPOX®E470 are uniformly dispersed systems of high-performance nano-spherical silica particles in epoxy resin. After synthesis and then surface modification, the spherical silica particles in the products have very small particle size (about 20nm) and extremely narrow particle size distribution. When mixed with bisphenol A epoxy resin, they can be used as a base resin to provide basic bonding and mechanical properties.

[0031] In some possible embodiments, the modified polyetheramine curing agent is prepared by the following method: heating and stirring the polyetheramine, after stirring evenly, adding isooctyl acrylate dropwise to the polyetheramine, the molar ratio of the polyetheramine to the isooctyl acrylate being 1:1, and continuing the reaction to obtain the modified polyetheramine curing agent.

[0032] In some possible embodiments, the structural formula of the modified polyetheramine curing agent is:

[0033]

[0034] The present invention utilizes isooctyl acrylate to modify conventional curing agent polyetheramine to obtain a modified polyetheramine curing agent with a branched structure. The branched structure is embedded in the crosslinking network during the crosslinking process between the modified polyetheramine curing agent and the epoxy resin, resulting in phase separation, forming a dense and loose alternating two-phase grid structure, thereby reducing the internal stress in the bottom filling glue, and achieving the effect of toughening and reducing the mold of the bottom filling glue. In a specific embodiment, 200g of polyetheramine D230 is added to a three-necked flask, and the flask is stirred evenly in a constant temperature water bath environment, and isooctyl acrylate is added dropwise, the molar ratio of isooctyl acrylate to polyetheramine is 1:1, and the reaction is carried out for 3.5 hours. According to the reaction situation, the stirring speed is adjusted so that the reaction can proceed smoothly, thereby obtaining a modified polyetheramine curing agent with a branched structure.

[0035] In some possible embodiments, the particle size of the spherical silica is 0.5-5 μm.

[0036] This is because the use of spherical silica as a filling material can not only reduce the thermal expansion coefficient and hygroscopicity of the bottom filling glue, but also improve the modulus of the bottom filling glue. The particle size of the spherical silica is selected to be 0.5 to 5 μm, which can be evenly dispersed in the matrix resin and can interact with the nano-silicon dioxide in the first epoxy resin to improve the packaging effect of the bottom filling glue.

[0037] In some possible embodiments, the model of the adhesion promoter includes Adherant1121.

[0038] The present invention can improve the connection between the bottom filling glue and the substrate, the SiO2 or Si3N4 passivation layer on the chip surface, improve the bonding strength between the bottom filling glue and the substrate surface, and improve the bonding strength between the base resin and the substrate or spherical silicon dioxide, so as to improve the packaging performance of the bottom filling glue.

[0039] Based on a general inventive concept, see Figure 1 The present application also provides a method for preparing the high-reliability single-component bottom filling glue as described in the first aspect, the preparation method comprising:

[0040] S1. Add each component into a stirring cup according to their respective mass percentages, and mix them evenly by a first centrifugal stirrer to obtain a first slurry; the mass percentages of the components specifically include: 50% to 60% spherical silica, 28% to 32% epoxy resin, 13% to 17% modified polyetheramine curing agent, 0.1% to 0.2% carbon black, 0.3% to 0.5% silane coupling agent, and 0.2% to 0.4% adhesion promoter; wherein the working parameters of the first centrifugal stirrer include: stirring time of 50 to 75 seconds, rotation of 800 r / min, and revolution of 1000 r / min;

[0041] S2, transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; wherein the working parameters of the three-roll mill include: a feed gap of 20 to 35 μm, and a discharge gap of 10 to 15 μm;

[0042] S3. Vacuum degassing the second slurry by a second centrifugal mixer to obtain a bottom filling glue, wherein the working parameters of the second centrifugal mixer include: vacuum degassing time of 55 to 70 seconds, rotation of 100 r / min, and revolution of 1000 r / min.

[0043] Based on a general inventive concept, the 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 high-reliability single-component bottom filling glue described in the first aspect.

[0044] 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.

[0045] The components of the raw materials in Comparative Examples 1-4 and Examples 1-3 are shown in Table 1 according to mass percentage:

[0046] Table 1 Distribution ratio of each group of raw materials

[0047]

[0048] The bottom filling glue provided in Examples 1-3 and Comparative Examples 1-4 was subjected to viscosity, fluidity, storage modulus and thermal expansion coefficient tests, high temperature storage test, high and low temperature cycle test and temperature and humidity unbiased high accelerated stress test. The specific test process is as follows:

[0049] 1. Test method for fluidity: Use 50um thick double-sided tape to stick the four corners of a 15mm wide, 20mm long, and 0.5mm thick copper pillar Si wafer to the substrate. Use a dispensing machine to dispense (35-40)mg of the bottom filling glue to be tested along one side of the square Si wafer. Place it on a 110℃ hot plate and start timing. Under the action of capillary force, the bottom filling glue will flow to the bottom of the Si wafer, and record the time when it is full.

[0050] 2. Storage modulus test method: Reference standard: ASTM E2254-2018, take a fully cured sample, prepare a test sample with a size of 55mm×10mm×3mm, measurement mode: dual cantilever mode, vibration frequency: 1Hz, amplitude: 10μm, heating rate: 5℃ / min;

[0051] 3. Thermal expansion coefficient test method: Reference standard: ASTM E831-2019, take a sample that is completely cured at 165°C for 2h, prepare a test sample with a size of 5mm×5mm×2mm, and test the thermal expansion coefficient and glass transition temperature (TMA) of the sample by TMA (compression mode); TMA parameter settings: preload force: 0.05N, first scan: room temperature-260°C (heating rate 10°C / min) second scan: room temperature-260°C (heating rate 5°C / min), take the curve data of the second heating section;

[0052] 4. High temperature storage test (HTST): The filled silicon wafer is completely cured at 150°C for 1000 hours to observe whether the silicon wafer is intact;

[0053] 5. High and Low Temperature Cycle Test (TCT): The filled silicon wafer is completely cured and cycled 1000 times at a temperature of -55 to 125°C to observe whether the silicon wafer is intact;

[0054] 6. Temperature and humidity unbiased highly accelerated stress test (uHAST): The sample is cast in a pudding mold with a diameter of 3mm and a height of 2mm. One end of the cast sample is in contact with the silicon wafer. The silicon wafer and the pudding mold are fixed. After curing at 165℃ / 2h, the pudding mold is removed, the sample is taken out, and tested with a thrust machine; it is carried out under the conditions of 130℃ and 85%RH for 96 hours. After taking it out, it is tested with a thrust machine; the thrust machine test speed is 50um / s and the contact height is 20um.

[0055] The test results are shown in Table 2 below:

[0056] Table 2 Test results

[0057]

[0058] From the above table, we can see that:

[0059] (1) In Comparative Example 1, epoxy resin E470 or E500 was not used. During the high-temperature storage test and the high-low temperature cycle test, the bottom filling glue and the silicon wafer were easily cracked, which affected the chip packaging performance;

[0060] (2) Comparative Example 2 uses conventional curing agent D230, and the storage modulus of the prepared bottom filling glue is relatively large. In addition, during the high-temperature storage test and the high-low temperature cycle test, the bottom filling glue and the silicon wafer are prone to cracking, which affects the chip packaging performance;

[0061] (3) Although Comparative Example 3-4 uses a modified polyetheramine curing agent and epoxy resin E470 / E500, the amount added is not within the range specified in the present application. The prepared bottom filling glue still cracks with the silicon wafer during the high-temperature storage test and the high-low temperature cycle test, affecting the chip packaging performance;

[0062] (4) The raw material formulas used in Examples 1-3 are all within the formula ratios specified in this application. The prepared bottom filling glue has a low thermal expansion coefficient and a suitable storage modulus, and can still be in close contact with the silicon wafer during high-temperature storage tests and high- and low-temperature cycle tests, thereby ensuring the reliability of chip packaging.

[0063] In summary, by using the bottom filling glue prepared within the specified range of the present application as the raw material components, and adjusting the ratio between the bisphenol A epoxy resin, the first epoxy resin and the modified polyether amine curing agent within a fixed range, a bottom filling glue with good fluidity, low thermal expansion coefficient and low modulus can be obtained, and the reliability of the bottom filling glue packaged chip can be maintained at high and low temperatures.

[0064] 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.

[0065] 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.

[0066] 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 reliability single component bottom filler, characterized in that: The bottom filling glue comprises the following components by mass percentage: 50% to 60% spherical silica, 28% to 32% epoxy resin, 13% to 17% modified polyetheramine curing agent, 0.1% to 0.2% carbon black, 0.3% to 0.5% silane coupling agent, and 0.2% to 0.4% adhesion promoter; the epoxy resin is composed of bisphenol A epoxy resin and a first epoxy resin, and the model of the first epoxy resin is NANOPOX® E500 or NANOPOX® E470; The mass percentage of the bisphenol A epoxy resin is 15% to 16%, and the mass percentage of the first epoxy resin is 14% to 15%; The modified polyetheramine curing agent is prepared by the following method: heating and stirring the polyetheramine, after stirring evenly, adding isooctyl acrylate dropwise to the polyetheramine, wherein the molar ratio of the polyetheramine to the isooctyl acrylate is 1:1, and continuing the reaction to obtain the modified polyetheramine curing agent; The structural formula of the modified polyetheramine curing agent is: 。 2. The high reliability one-component bottom filling adhesive according to claim 1, characterized in that: The type of the bisphenol A epoxy resin includes at least one of E44, DER321 and DER324.

3. The high reliability one-component bottom filling adhesive according to claim 2, characterized in that: The particle size of the spherical silicon dioxide is 0.5 to 5 μm.

4. The high reliability one-component bottom filling adhesive according to claim 3, characterized in that: The adhesion promoter includes Adherant1121.

5. A method for preparing a high-reliability single-component bottom filling adhesive as claimed in any one of claims 1 to 4, characterized in that: The preparation method comprises: S1. Add each component into a stirring cup according to their respective mass percentages, and mix them evenly by a first centrifugal stirrer to obtain a first slurry; the mass percentages of the components specifically include: 50% to 60% spherical silica, 28% to 32% epoxy resin, 13% to 17% modified polyether amine curing agent, 0.1% to 0.2% carbon black, 0.3% to 0.5% silane coupling agent, and 0.2% to 0.4% adhesion promoter; 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 using a second centrifugal mixer to obtain a bottom filling adhesive.

6. The method for preparing a high-reliability single-component bottom filling adhesive according to claim 5, characterized in that: The working parameters of the first centrifugal mixer include: stirring time of 50 to 75 seconds, rotation of 800 r / min, revolution of 1000 r / min; The working parameters of the three-roll mill include: the feed gap is 20-35 μm, the discharge gap is 10-15 μm; The working parameters of the second centrifugal mixer include: vacuum degassing time of 55 to 70 seconds, rotation of 100 r / min, and revolution of 1000 r / min.

7. 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-reliability single-component bottom filling glue according to any one of claims 1 to 4.

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