Low expansion coefficient epoxy film and preparation method thereof, and preparation method of packaged wafer

Abstract

The invention provides a low expansion coefficient epoxy film and a preparation method thereof, and a preparation method for a packaged wafer. The low expansion coefficient epoxy film comprises the following components by mass percentage: 77% to 88% of silicon dioxide, 6% to 9% of modified resin, 1% to 2% of polybenzoxazine resin, 0% to 4% of liquid epoxy resin, 0% to 6% of olefin liquid rubber, 4% to 6% of phenolic curing agent, 0.1% to 0.3% of imidazole accelerator, 0.4% to 0.6% of dye, and 1% to 2% of silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin; the thermal expansion coefficient and internal stress of the epoxy film are reduced by the synergistic effect of the raw material components, the mechanical properties of the epoxy film are improved, and then the warping of the epoxy film is reduced while the mechanical properties of the epoxy film are maintained, so as to ensure the stability of wafer packaging.

Description

Technical Field

[0001] The invention belongs to the technical field of chip packaging, and particularly relates to a low expansion coefficient epoxy film and a preparation method thereof, and a preparation method of a packaging wafer. Background Art

[0002] Wafer-level packaging is an advanced packaging technology, whose main feature is to perform packaging operations directly on silicon wafers, and then cut the packaged wafers into individual chips. The main advantages of this packaging method are that it improves packaging efficiency and reduces costs, and because the use of materials is reduced during the packaging process, the size of the packaged chip is close to or even equal to the size of the bare die on the wafer. At the same time, since the packaging process is completed on the wafer, after the steps of thermal curing and thermal reflow are completed, each part of the material accumulates a large stress, which manifests itself as warping deformation to varying degrees in the macroscopic sense. The occurrence of warping deformation will reduce the process accuracy of subsequent packaging process steps such as thinning and cutting and affect subsequent automated operations, and will also bring a lot of problems to product reliability.

[0003] Therefore, how to provide a low expansion coefficient epoxy film to reduce the warping of the epoxy film is a technical problem that those skilled in the art need to solve urgently. Summary of the invention

[0004] The object of the present invention is to provide a low expansion coefficient epoxy film and a preparation method thereof, and a preparation method of a packaged wafer, 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 low expansion coefficient epoxy film, which comprises the following components by mass percentage: 77% to 88% of silicon dioxide, 6% to 9% of modified resin, 1% to 2% of polybenzoxazine resin, 0% to 4% of liquid epoxy resin, 0% to 6% of olefin liquid rubber, 4% to 6% of phenolic curing agent, 0.1% to 0.3% of imidazole accelerator, 0.4% to 0.6% of dye, and 1% to 2% of silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin.

[0006] In the first aspect, the epoxy film comprises the following components by mass percentage: 78% to 85% silicon dioxide, 6% to 9% modified resin, 1% to 2% polybenzoxazine resin, 2% to 4% liquid epoxy resin, 0.5% to 4% olefin liquid rubber, 4% to 6% phenolic curing agent, 0.1% to 0.3% imidazole accelerator, 0.4% to 0.6% dye, and 1% to 2% silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin.

[0007] In the first aspect, the epoxy film comprises the following components by mass percentage: 78% to 83% silicon dioxide, 6% to 9% modified resin, 1% to 2% polybenzoxazine resin, 5% to 6% olefin liquid rubber, 4% to 6% phenolic curing agent, 0.1% to 0.3% imidazole accelerator, 0.4% to 0.6% dye, and 1% to 2% silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin.

[0008] In the first aspect, the epoxy film comprises the following components by mass percentage: 78% to 85% silicon dioxide, 6% to 9% modified resin, 1% to 2% polybenzoxazine resin, 3% to 4% liquid epoxy resin, 4% to 6% phenolic curing agent, 0.1% to 0.3% imidazole accelerator, 0.4% to 0.6% dye, and 1% to 2% silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin.

[0009] In the first aspect, the average particle size of the silicon dioxide is 3 to 10 μm.

[0010] In the first aspect, the liquid epoxy resin includes at least one of a bisphenol A type liquid epoxy resin and a bisphenol F type liquid epoxy resin.

[0011] In the first aspect, the imidazole accelerator includes at least one of 4-methyl-2-phenylimidazole and 2-ethyl-4-methylimidazole.

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

[0013] The second aspect of the present invention provides a method for preparing a low expansion coefficient epoxy film as described in the first aspect, the preparation method comprising: mixing the components according to their respective mass percentages, stirring evenly, transferring to a three-roll grinder for further mixing to obtain a first slurry, wherein the mass percentages of the components specifically include: 77% to 88% silicon dioxide, 6% to 9% modified resin, 1% to 2% polybenzoxazine resin, 0% to 4% liquid epoxy resin, 0% to 6% olefin liquid rubber, 4% to 6% phenolic curing agent, 0.1% to 0.3% imidazole accelerator, 0.4% to 0.6% dye, and 1% to 2% silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin; vacuum degassing the first slurry by a centrifugal mixer to obtain a second slurry; coating the second slurry on a base film by a coating machine, and drying at 120°C to obtain a low expansion coefficient epoxy film.

[0014] The third aspect of the present invention provides a method for preparing a packaged wafer, the preparation method comprising: stirring and mixing the components in the low expansion coefficient epoxy film described in the first aspect, and after stirring evenly, transferring to a three-roll grinder for further mixing to obtain a first slurry, wherein the mass percentages of the components specifically include: 77% to 88% silicon dioxide, 6% to 9% modified resin, 1% to 2% polybenzoxazine resin, 0% to 4% liquid epoxy resin, 0% to 6% olefin liquid rubber, 4% to 6% phenolic curing agent, and 0.1% to 0.2% imidazole accelerator. 0.3%, dye 0.4% to 0.6%, silane coupling agent 1% to 2%; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin; the first slurry is vacuum degassed by a centrifugal mixer to obtain a second slurry; the second slurry is coated on a base film by a coater and dried at 120°C to obtain a low expansion coefficient epoxy film; the low expansion coefficient epoxy film is covered on a wafer by vacuum hot pressing, the base film is removed, and after curing, a packaged wafer is obtained.

[0015] Beneficial Effects

[0016] The invention provides a low expansion coefficient epoxy film, which comprises the following components by mass percentage: 77% to 88% of silicon dioxide, 6% to 9% of modified resin, 1% to 2% of polybenzoxazine resin, 0% to 4% of liquid epoxy resin, 0% to 6% of olefin liquid rubber, 4% to 6% of phenolic curing agent, 0.1% to 0.3% of imidazole accelerator, 0.4% to 0.6% of dye, and 1% to 2% of silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin; the modified resin formed by compounding multiple resins is used as a base resin to provide basic properties for the epoxy film, and the liquid epoxy resin is added to improve the mechanical properties of the epoxy film; the polybenzoxazine resin can not only reduce the shrinkage rate, but also act as a curing agent to improve the degree of crosslinking; the olefin liquid rubber can also reduce the shrinkage rate, and can also act as a curing agent to improve the degree of crosslinking; The end of the hydrocarbon liquid rubber contains an active reactive group, which can further increase the chain length and improve the toughness of the epoxy film, thereby reducing the internal stress; the phenolic curing agent undergoes an addition curing reaction with the epoxy resin, and the strength of the epoxy film is improved by combining with the polybenzoxazine resin, and the curing time is shortened by using an imidazole accelerator; the present invention uses the compounded modified resin to provide basic properties for the epoxy film, and by adjusting the ratio between silicon dioxide, liquid epoxy resin, olefin liquid rubber and phenolic curing agent, and combining the structural characteristics of the polybenzoxazine resin, the thermal expansion coefficient and internal stress of the epoxy film are reduced through synergistic effect, and the mechanical properties of the epoxy film are improved, thereby reducing the warping of the epoxy film while maintaining the mechanical properties of the epoxy film. In addition, a silane coupling agent is introduced to further improve the adhesion between the epoxy film and the wafer, thereby ensuring the efficiency of wafer packaging. 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 The present invention provides a flow chart of a method for preparing a low expansion coefficient epoxy film. DETAILED DESCRIPTION

[0019] 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.

[0020] 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.

[0021] 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.

[0022] The present invention provides a low expansion coefficient epoxy film, which comprises the following components by mass percentage: 77% to 88% of silicon dioxide, 6% to 9% of modified resin, 1% to 2% of polybenzoxazine resin, 0% to 4% of liquid epoxy resin, 0% to 6% of olefin liquid rubber, 4% to 6% of phenolic curing agent, 0.1% to 0.3% of imidazole accelerator, 0.4% to 0.6% of dye, and 1% to 2% of silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin.

[0023] Specifically, the present invention provides a low expansion coefficient epoxy film, which includes the following components by mass percentage: 77% to 88% of silicon dioxide, 6% to 9% of modified resin, 1% to 2% of polybenzoxazine resin, 0% to 4% of liquid epoxy resin, 0% to 6% of olefin liquid rubber, 4% to 6% of phenolic curing agent, 0.1% to 0.3% of imidazole accelerator, 0.4% to 0.6% of dye, and 1% to 2% of silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin; the modified resin formed by compounding multiple resins is used as the base resin to provide basic properties for the epoxy film, and the liquid epoxy resin is added to improve the mechanical properties of the epoxy film; the polybenzoxazine resin can not only reduce the shrinkage rate, but also act as a curing agent to improve the crosslinking degree. degree; the end of the olefin liquid rubber contains an active reactive group, which can further increase the chain length and improve the toughness of the epoxy film, thereby reducing the internal stress; the phenolic curing agent undergoes an addition curing reaction with the epoxy resin, and the strength of the epoxy film is improved by combining with the polybenzoxazine resin, and the curing time is shortened by using an imidazole accelerator; the present invention uses the compounded modified resin to provide basic properties for the epoxy film, and by adjusting the ratio between silicon dioxide, liquid epoxy resin, olefin liquid rubber and phenolic curing agent, and combining the structural characteristics of the polybenzoxazine resin, the thermal expansion coefficient and internal stress of the epoxy film are reduced through synergistic effect, the mechanical properties of the epoxy film are improved, and then the warping of the epoxy film is reduced while maintaining the mechanical properties of the epoxy film. In addition, a silane coupling agent is introduced to further improve the adhesion between the epoxy film and the wafer, thereby ensuring the efficiency of wafer packaging.

[0024] In a specific embodiment, phenoxy resin is a type of thermoplastic amorphous resin prepared by polycondensation of bisphenol A and epichlorohydrin, contains secondary hydroxyl groups in its molecular structure, can undergo cross-linking reaction with phenolic curing agents, has excellent thermal stability, bonding strength, and corrosion resistance, and the preferred model is SQP50; naphthalene epoxy resin has ultra-high heat resistance and low thermal expansion, and its epoxy equivalent is 195-210g / eq, which reduces the thermal expansion coefficient of epoxy film, and the preferred model is HP4770 or HP4710; dicyclopentadiene resin has the advantages of good tackifying effect and strong stability, so as to improve the bonding strength of epoxy film, and its epoxy equivalent is 250-280g / eq, and the preferred model is HP7200, SQDN-301 or SQDN-302; polyurethane modified epoxy resin is an interpenetrating polymer formed by blending high elastic polyurethane and epoxy resin The IPN structure of the physical network has high bonding strength, heat shock resistance and good creep resistance to improve the bonding strength of the epoxy film, and the preferred model is EPU-133; the modified resin is formed by mixing four resins to provide basic performance for the epoxy film, and the mass percentages of the four resins in the epoxy film are: the mass percentage of phenoxy resin is 1.44%, the mass percentage of naphthalene epoxy resin is 1.86%, the mass percentage of dicyclopentadiene resin is 2.60%, and the mass percentage of polyurethane modified epoxy resin is 1.61%; the modified resin compounded with the above ratio has good mechanical properties and thermal properties, and combined with other raw material components, the thermal expansion coefficient and warpage of the epoxy film can be reduced through synergistic effect, while the bonding strength of the epoxy film is improved, so that the epoxy film can stably cover the wafer, thereby controlling the warpage of the wafer.

[0025] In some possible embodiments, the epoxy film includes the following components in mass percentage: 78% to 85% silicon dioxide, 6% to 9% modified resin, 1% to 2% polybenzoxazine resin, 2% to 4% liquid epoxy resin, 0.5% to 4% olefin liquid rubber, 4% to 6% phenolic curing agent, 0.1% to 0.3% imidazole accelerator, 0.4% to 0.6% dye, and 1% to 2% silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin.

[0026] In some possible embodiments, the epoxy film includes the following components in mass percentage: 78% to 83% silicon dioxide, 6% to 9% modified resin, 1% to 2% polybenzoxazine resin, 5% to 6% olefin liquid rubber, 4% to 6% phenolic curing agent, 0.1% to 0.3% imidazole accelerator, 0.4% to 0.6% dye, and 1% to 2% silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin.

[0027] In some possible embodiments, the epoxy film includes the following components by mass percentage: 78% to 85% silicon dioxide, 6% to 9% modified resin, 1% to 2% polybenzoxazine resin, 3% to 4% liquid epoxy resin, 4% to 6% phenolic curing agent, 0.1% to 0.3% imidazole accelerator, 0.4% to 0.6% dye, and 1% to 2% silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin.

[0028] In some possible embodiments, the average particle size of the silicon dioxide is 3 to 10 μm.

[0029] In some possible embodiments, the liquid epoxy resin includes at least one of bisphenol A liquid epoxy resin and bisphenol F liquid epoxy resin.

[0030] Those skilled in the art can understand that the liquid epoxy resin includes bisphenol A type liquid epoxy resin or bisphenol F type liquid epoxy resin, and the mechanical strength of the epoxy film is improved by the liquid epoxy resin.

[0031] In some possible embodiments, the imidazole accelerator includes at least one of 4-methyl-2-phenylimidazole and 2-ethyl-4-methylimidazole.

[0032] This is because the addition of the imidazole accelerator to the formulation of the present invention can promote the cross-linking reaction between the resin and the phenolic curing agent, reduce the reaction time, and improve the cross-linking curing efficiency.

[0033] In some possible embodiments, the colorant includes carbon black; and the silane coupling agent includes at least one of γ-glycidyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane.

[0034] Those skilled in the art will appreciate that adding a silane coupling agent to the formulation of the present invention further enhances the bonding strength with the chip / wafer to improve the stability of the chip / wafer packaging.

[0035] Based on a general inventive concept, see Figure 1 The second aspect of the present invention provides a method for preparing the low expansion coefficient epoxy film as described in the first aspect, the preparation method comprising:

[0036] S1. Mix the components according to their respective mass percentages, stir evenly, and transfer to a three-roll mill for further mixing to obtain a first slurry, wherein the mass percentages of the components specifically include: 77% to 88% silicon dioxide, 6% to 9% modified resin, 1% to 2% polybenzoxazine resin, 0% to 4% liquid epoxy resin, 0% to 6% olefin liquid rubber, 4% to 6% phenolic curing agent, 0.1% to 0.3% imidazole accelerator, 0.4% to 0.6% dye, and 1% to 2% silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin, and polyurethane modified epoxy resin;

[0037] S2, vacuum degassing the first slurry by a centrifugal mixer to obtain a second slurry;

[0038] S3. Coat the second slurry on the base film by a coating machine, and dry it at 120° C. to obtain a low expansion coefficient epoxy film.

[0039] Specifically, the present invention provides a method for preparing a low expansion coefficient epoxy film. First, each component of the raw material is accurately weighed, mixed and stirred for 60 to 120 seconds. After stirring evenly, the mixture is transferred to a three-roll grinder for grinding, and the feeding gap in the three-roll grinder is set to 20 to 50 μm, and the discharging gap is set to 15 to 30 μm to obtain a first slurry; then, a centrifugal stirrer is used to vacuum degas the first slurry, and the centrifugal stirrer is set to rotate at 1200 r / min and revolve at 1400 r / min, and the vacuum degassing time is 60 to 120 seconds to obtain a second slurry; finally, the second slurry is coated on the base film by a coater, and dried at 120°C to obtain a low expansion coefficient epoxy film.

[0040] Based on a general inventive concept, the third aspect of the present invention provides a method for preparing a packaged wafer, the method comprising:

[0041] S1. Stir and mix the components of the low expansion coefficient epoxy film described in the first aspect, and after stirring evenly, transfer to a three-roll grinder for further mixing to obtain a first slurry, wherein the mass percentage of the components specifically includes: 77% to 88% silicon dioxide, 6% to 9% modified resin, 1% to 2% polybenzoxazine resin, 0% to 4% liquid epoxy resin, 0% to 6% olefin liquid rubber, 4% to 6% phenolic curing agent, 0.1% to 0.3% imidazole accelerator, 0.4% to 0.6% dye, and 1% to 2% silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin;

[0042] S2, vacuum degassing the first slurry by a centrifugal mixer to obtain a second slurry;

[0043] S3, coating the second slurry on the base film by a coating machine, and drying at 120° C. to obtain a low expansion coefficient epoxy film;

[0044] S4, covering the low expansion coefficient epoxy film on the wafer by vacuum hot pressing, removing the base film, and obtaining a packaged wafer after curing.

[0045] The low expansion coefficient epoxy film prepared by the preparation method of the second aspect of the present invention is covered on the wafer by vacuum hot pressing, the base film is removed, and then cured at 150°C. During the curing process, the adhesion between the epoxy film and the wafer is strong, which can prevent the wafer from warping under the action of the epoxy film, thereby obtaining a wafer with stable packaging.

[0046] 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.

[0047] The components of the epoxy films in Examples 1-6 and Comparative Examples 1-3 are shown in Table 1 according to mass percentage:

[0048] Table 1 Distribution ratio of each group of raw materials

[0049]

[0050] The epoxy films provided in Examples 1-6 and Comparative Examples 1-3 were tested for storage modulus, glass transition temperature and thermal expansion coefficient, copper sheet adhesion and warpage. The specific testing process is as follows:

[0051] 1. Storage modulus test: Reference standard: ASTM E2254-2018, take a sample that is completely cured at 150°C for 1.5h, the size of the test sample is 55mm×10mm×2mm, and DMA is used for measurement. The measurement mode is dualcantilever mode, vibration frequency: 1Hz, amplitude: 10μm, heating rate: 5°C / min; the storage modulus takes the value of 30°C-200°C.

[0052] 2. Glass transition temperature Tg: Reference standard: ASTM E2254-2018, take a sample that is completely cured at 150°C for 1.5h, prepare a test sample with a size of 55mm×10mm×2mm, and use DMA for measurement, measurement mode: dualcantilever mode, vibration frequency: 1Hz, amplitude: 10μm, heating rate: 5°C / min;

[0053] 3. Thermal expansion coefficient: Reference standard: ASTM E831-2019, take a sample that is completely cured at 150℃ for 1.5h, and prepare a test sample with a size of 5mm×5mm×2mm. Use TMA (compression mode) to test the thermal expansion coefficient of the sample. TMA parameter settings: preload force: 0.05N, first scan: room temperature-220℃ (heating rate 10℃ / min); second scan: room temperature-220℃ (heating rate 10℃ / min), take the curve data of the second heating section; the expansion coefficient CTE1 / 2 takes the values ​​of 50℃-80℃ and 180℃-210℃ respectively;

[0054] 4. Test of copper sheet adhesion: a 2mm×2mm film with a thickness of 200μm was transferred to the copper sheet, and after curing at 150℃ for 1.5h, the shear bonding strength was tested with a universal tensile machine;

[0055] 5. Warp test: After the formula is made into slurry, it is coated into a 200 μm thick film, cut into samples of size 20 mm × 20 mm, and the light release film is torn off. The film is heat-transferred to a round glass sheet with a thickness of 150 μm and a diameter of 10 cm under 120°C / 0.2 MPa pressure conditions, and the heavy release film is torn off. The film at the edge of the glass sheet is cut cleanly, and placed in an oven to cure at 150°C / 1.5h. After curing, it is naturally cooled to room temperature. After being placed at room temperature for 24h, the warpage of the glass sheet is measured with a steel ruler.

[0056] The test results are shown in Table 2 below:

[0057] Table 2 Test results

[0058]

[0059] From the above table, we can see that:

[0060] (1) Compared with Comparative Example 1 and Comparative Example 3, Example 1 and Examples 3-5 all add liquid epoxy resin and olefin liquid rubber. By controlling the addition ratio of liquid epoxy resin and olefin liquid rubber, the thermal expansion coefficient and glass transition temperature of the epoxy film can be reduced, and the warping of the epoxy film can be reduced, so that when the epoxy film is used to encapsulate the wafer, the warping of the wafer can be reduced, thereby improving the stability of the electronic device;

[0061] (2) From the data of Example 2, it can be seen that when liquid epoxy resin is not added to the formula, it is necessary to increase the mass percentage of olefin liquid rubber, and use the end group activity of olefin liquid rubber to increase the chain length, reduce internal stress, and thus reduce the warping of the epoxy film;

[0062] (3) From the data of Example 6 and Comparative Example 2, it can be seen that when no olefin liquid rubber is added to the formula, it is necessary to reduce the mass percentage of the liquid epoxy resin and add silicon dioxide to reduce the thermal expansion coefficient of the epoxy film, thereby reducing the warpage of the epoxy film;

[0063] (4) From the data of Example 1 and Examples 4-6, it can be seen that when the mass percentage of the liquid epoxy resin in the formula is fixed, the degree of cross-linking in the cross-linking curing reaction can be controlled by adjusting the ratio of silica, olefin liquid rubber and phenolic curing agent, thereby reducing the warping of the epoxy film.

[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 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.

[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 low expansion coefficient epoxy film, characterized in that: The epoxy film includes the following components by mass percentage: 78% to 85% silicon dioxide, modified resin, 1% to 2% polybenzoxazine resin, 2% to 4% liquid epoxy resin, 0.5% to 4% olefin liquid rubber, 4% to 6% phenolic curing agent, 0.1% to 0.3% imidazole accelerator, 0.4% to 0.6% dye, and 1% to 2% silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin; the mass percentage of the phenoxy resin is 1.44%, the mass percentage of the naphthalene epoxy resin is 1.86%, the mass percentage of the dicyclopentadiene resin is 2.60%, and the mass percentage of the polyurethane modified epoxy resin is 1.61%.

2. A low expansion coefficient epoxy film, characterized in that: The epoxy film includes the following components by mass percentage: 78% to 83% silicon dioxide, modified resin, 1% to 2% polybenzoxazine resin, 5% to 6% olefin liquid rubber, 4% to 6% phenolic curing agent, 0.1% to 0.3% imidazole accelerator, 0.4% to 0.6% dye, and 1% to 2% silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin; the mass percentage of the phenoxy resin is 1.44%, the mass percentage of the naphthalene epoxy resin is 1.86%, the mass percentage of the dicyclopentadiene resin is 2.60%, and the mass percentage of the polyurethane modified epoxy resin is 1.61%.

3. A low expansion coefficient epoxy film, characterized in that: The epoxy film includes the following components by mass percentage: 78% to 85% silicon dioxide, modified resin, 1% to 2% polybenzoxazine resin, 3% to 4% liquid epoxy resin, 4% to 6% phenolic curing agent, 0.1% to 0.3% imidazole accelerator, 0.4% to 0.6% dye, and 1% to 2% silane coupling agent; wherein the modified resin is composed of phenoxy resin, naphthalene epoxy resin, dicyclopentadiene resin and polyurethane modified epoxy resin; the mass percentage of the phenoxy resin is 1.44%, the mass percentage of the naphthalene epoxy resin is 1.86%, the mass percentage of the dicyclopentadiene resin is 2.60%, and the mass percentage of the polyurethane modified epoxy resin is 1.61%.

4. The low expansion coefficient epoxy film according to any one of claims 1 to 3, characterized in that: The average particle size of the silicon dioxide is 3 to 10 μm.

5. The low expansion coefficient epoxy film according to claim 4, characterized in that: The liquid epoxy resin includes at least one of bisphenol A type liquid epoxy resin and bisphenol F type liquid epoxy resin.

6. The low expansion coefficient epoxy film according to claim 5, characterized in that: The imidazole accelerator includes at least one of 4-methyl-2-phenylimidazole and 2-ethyl-4-methylimidazole.

7. The low expansion coefficient epoxy film according to claim 6, characterized in that: The coloring agent includes carbon black; The silane coupling agent includes at least one of γ-glycidyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane.

8. A method for preparing a low expansion coefficient epoxy film according to any one of claims 1 to 7, characterized in that: The preparation method comprises: The components are mixed according to their respective mass percentages, stirred evenly, and then transferred to a three-roll mill for further mixing to obtain a first slurry; vacuum degassing the first slurry by a centrifugal mixer to obtain a second slurry; The second slurry is coated on the base film by a coating machine and dried at 120° C. to obtain a low expansion coefficient epoxy film.

9. A method for preparing a packaged wafer, characterized in that: The preparation method comprises: The components of the low expansion coefficient epoxy film according to any one of claims 1 to 7 are stirred and mixed, and after being stirred evenly, they are transferred to a three-roll mill for further mixing to obtain a first slurry; wherein the modified resin is composed of a phenoxy resin, a naphthalene epoxy resin, a dicyclopentadiene resin and a polyurethane modified epoxy resin; vacuum degassing the first slurry by a centrifugal mixer to obtain a second slurry; The second slurry is coated on the base film by a coating machine, and dried at 120° C. to obtain a low expansion coefficient epoxy film; The low expansion coefficient epoxy film is covered on the wafer by vacuum hot pressing, and the base film is removed and cured to obtain a packaged wafer.

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