Low-warpage and high-stability film sealing adhesive, preparation method thereof and chip packaging method

Abstract

The invention provides a low-warpage and high-stability film sealing adhesive, a preparation method thereof and a chip packaging method. The film sealing adhesive comprises the following components in percentage by mass: 80%-84% of epoxy modified silicon dioxide, 7%-9% of alicyclic epoxy resin, 8%-10% of an anhydride curing agent, 0.1%-0.2% of a dispersing agent, 0.4%-0.6% of a core-shell structure additive, 0.2%-0.3% of a flatting agent and 0.1%-0.2% of carbon black. The proportion of the epoxy modified silicon dioxide, the alicyclic epoxy resin and the anhydride curing agent is adjusted, and the dispersing agent, the core-shell structure additive and the flatting agent are combined, so that the sedimentation of the filler is reduced, and the internal stress of the film sealing adhesive is alleviated, so that the storage stability of the film sealing adhesive is improved, and the warping of the cured film sealing adhesive is reduced; the surface of the film sealing adhesive has good leveling performance after being printed, and the chip packaging yield can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of chip packaging, and in particular relates to a film sealing adhesive with low warpage and high stability, a preparation method thereof, and a chip packaging method. Background Art

[0002] With the rapid development of microelectronics industries such as consumer electronics, smart furniture, smart phones, new energy vehicles, and communication base stations, electronic products are playing an increasingly important role in people's lives. At the same time, this has put forward higher requirements for the development of the integrated circuit and semiconductor industries, requiring electronic devices to develop towards miniaturization, micro-miniaturization, and high integration, which has also put forward higher requirements for packaging materials.

[0003] As a material for packaging chips or wafers, film sealants have the characteristics of protecting circuits from external environmental influences. However, the existing film sealants have large changes in viscosity during storage, poor stability, and high warpage after curing, which affects the service life of the chip.

[0004] It can be seen that how to provide a film sealant with low warping and high stability, improve the stability of the film sealant by adjusting the ratio between epoxy-modified silica, alicyclic epoxy resin and anhydride curing agent, and reduce the warping of the film sealant after curing, thereby improving the reliability of chip packaging is a technical problem that technical personnel in this field need to solve urgently. Summary of the invention

[0005] The object of the present invention is to provide a film sealant with low warpage and high stability and a preparation method thereof, and a chip packaging method, so as to solve at least one of the above-mentioned technical problems.

[0006] To achieve the above-mentioned purpose, the first aspect of the present invention provides a low-warping and high-stability film sealant, which comprises the following components by mass percentage: 80% to 84% epoxy-modified silica, 7% to 9% alicyclic epoxy resin, 8% to 10% anhydride curing agent, 0.1% to 0.2% dispersant, 0.4% to 0.6% core-shell structure additive, 0.2% to 0.3% leveling agent, and 0.1% to 0.2% carbon black.

[0007] In the first aspect, the structural formula of the alicyclic epoxy resin is: .

[0008] In the first aspect, the outer shell of the core-shell structure auxiliary agent is methyl methacrylate, and the inner core of the core-shell structure auxiliary agent is BS resin.

[0009] In the first aspect, the acid anhydride curing agent is methylhexahydrophthalic anhydride.

[0010] In the first aspect, the particle size of the epoxy-modified silica is 5-28 μm.

[0011] In the first aspect, the model of the dispersant includes at least one of 1103 and 1401.

[0012] In the first aspect, the leveling agent includes at least one of BYK-333 and BYK-320.

[0013] The second aspect of the present invention provides a method for preparing a low-warping and high-stability film sealant as described in the first aspect, the preparation method comprising: S1, accurately weighing the raw material components, wherein the components specifically include, by mass percentage: 80% to 84% epoxy-modified silica, 7% to 9% alicyclic epoxy resin, 8% to 10% anhydride curing agent, 0.1% to 0.2% dispersant, 0.4% to 0.6% core-shell structure additive, 0.2% to 0.3% leveling agent, and 0.1% to 0.2% carbon black; S2, weighing the alicyclic epoxy resin The resin and the core-shell structure additive are added into a stirring cup, and stirred evenly by a first centrifugal stirrer to obtain a premix; S3, the epoxy-modified silica, the anhydride curing agent, the dispersant, the leveling agent and the carbon black are added into the premix, and stirred evenly by a second centrifugal stirrer to obtain a first slurry; S4, the first slurry is transferred to a three-roll grinder for dispersion treatment to obtain a uniformly dispersed second slurry; S5, the second slurry is vacuum degassed by a third centrifugal stirring to obtain a membrane sealing glue with low warping and high stability.

[0014] In the second aspect, the working parameters of the first centrifugal mixer include: stirring time of 30 to 60 s, rotation of 800 r / min, and revolution of 1000 r / min; the working parameters of the second centrifugal mixer include: stirring time of 180 to 200 s, rotation of 1200 r / min, and revolution of 1500 r / min; the working parameters of the three-roll grinder include: feeding gap of 100 to 120 μm, and discharging gap of 70 to 90 μm; the working parameters of the third centrifugal mixer include: vacuum degassing time of 60 to 80 s, rotation of 800 r / min, and revolution of 1000 r / min.

[0015] The third aspect of the present invention provides a chip packaging method, which includes: obtaining a wafer body; arranging copper pillars at equal intervals on the front side of the wafer body, and cutting a semicircular groove on the front side of the wafer body between two adjacent copper pillars to obtain a cut wafer; applying the low-warping and high-stability film sealing glue described in the first aspect to the front side of the cut wafer to obtain a packaged wafer; grinding the front side of the packaged wafer to expose the copper pillars, and grinding the back side of the packaged wafer to expose the film sealing glue to obtain a ground wafer; applying the film sealing glue on the back side of the ground wafer, and continuing to cut along the gap cut by the semicircular groove to obtain a number of well-packaged chips.

[0016] Beneficial effects: The present invention provides a low-warping and high-stability film sealant, which comprises the following components by mass percentage: 80% to 84% of epoxy-modified silica, 7% to 9% of alicyclic epoxy resin, 8% to 10% of anhydride curing agent, 0.1% to 0.2% of a dispersant, 0.4% to 0.6% of a core-shell structure additive, 0.2% to 0.3% of a leveling agent, and 0.1% to 0.2% of carbon black; the alicyclic epoxy resin has high toughness and low shrinkage after curing, has low viscosity after cross-linking and curing with anhydride curing agent, and is easy to print; the mechanical strength of the film sealant can be improved by epoxy-modified silica, and the sedimentation of silica can be effectively reduced by combining with the dispersant Phenomenon, thereby improving the storage stability of the film sealant; the core-shell structure additive can enhance the impact resistance of the film sealant, has the effect of alleviating the internal stress of the film sealant, and is beneficial to reducing the warping of the film sealant after curing; the leveling agent can reduce the surface tension of the film sealant and improve the leveling performance of the film sealant after printing; the present application adjusts the ratio between epoxy-modified silica, alicyclic epoxy resin and acid anhydride curing agent, and combines dispersant, core-shell structure additive and leveling agent to reduce the sedimentation of filler and alleviate the internal stress of the film sealant, thereby improving the storage stability of the film sealant and reducing the warping of the film sealant after curing, so that the surface of the film sealant has good leveling performance after printing, which can improve the chip 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 This is a flow chart of a method for preparing a film sealant with low warpage and high stability in this application; Figure 2A chip packaging method in this application Figure 1 ; Figure 3 A chip packaging method process in this application Figure 2 . 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 application provides a low-warping and high-stability film sealant, which includes the following components by mass percentage: 80% to 84% epoxy-modified silica, 7% to 9% alicyclic epoxy resin, 8% to 10% anhydride curing agent, 0.1% to 0.2% dispersant, 0.4% to 0.6% core-shell structure additive, 0.2% to 0.3% leveling agent, and 0.1% to 0.2% carbon black.

[0023] Specifically, the present invention provides a low-warping and high-stability film sealant, which includes the following components by mass percentage: 80% to 84% epoxy-modified silica, 7% to 9% alicyclic epoxy resin, 8% to 10% anhydride curing agent, 0.1% to 0.2% dispersant, 0.4% to 0.6% core-shell structure additive, 0.2% to 0.3% leveling agent, and 0.1% to 0.2% carbon black; the alicyclic epoxy resin has high toughness and low shrinkage after curing, and has low viscosity after cross-linking and curing with anhydride curing agent, and is easy to print; the mechanical strength of the film sealant can be improved by epoxy-modified silica, and the silica emission can be effectively reduced by combining with the dispersant The core-shell structure additive can enhance the impact resistance of the film sealant, has the effect of relieving the internal stress of the film sealant, and is beneficial to reduce the warping of the film sealant after curing; the leveling agent can reduce the surface tension of the film sealant and improve the leveling performance of the film sealant after printing; the present application adjusts the ratio between epoxy-modified silica, alicyclic epoxy resin and acid anhydride curing agent, and combines dispersant, core-shell structure additive and leveling agent to reduce the sedimentation of filler and relieve the internal stress of the film sealant, thereby improving the storage stability of the film sealant and reducing the warping of the film sealant after curing, so that the surface of the film sealant has good leveling performance after printing, which can improve the chip packaging yield.

[0024] In some possible embodiments, the structural formula of the alicyclic epoxy resin is: .

[0025] Those skilled in the art will appreciate that alicyclic epoxy resins have high toughness and a low shrinkage rate of the system after curing, which can reduce stress concentration and cracking problems caused by shrinkage. In a specific embodiment, the alicyclic epoxy resin can be selected as EHPE 3150 or 2021P.

[0026] In some possible embodiments, the outer shell of the core-shell structure auxiliary agent is methyl methacrylate, and the inner core of the core-shell structure auxiliary agent is BS resin.

[0027] This is because the shell of the core-shell structure additive is methyl methacrylate and the core is BS resin. The methyl methacrylate-butadiene-styrene copolymer thus formed has excellent impact resistance and can relax stress when used in film sealants, thereby reducing the warpage of the film sealants. In a specific embodiment, the model of the core-shell structure additive that can be selected is Metablen C223A.

[0028] In some possible embodiments, the anhydride curing agent is methylhexahydrophthalic anhydride.

[0029] In some possible embodiments, the particle size of the epoxy-modified silica is 5-28 μm.

[0030] Those skilled in the art can understand that methyl hexahydrophthalic anhydride is a heating curing agent and does not react with epoxy resin at room temperature, so that the prepared film sealant can be stored at room temperature, which is conducive to the printing of film sealant, and undergoes a cross-linking and curing reaction with alicyclic epoxy resin under a certain stability. The curing shrinkage rate of the reaction system is low, which can effectively reduce the warping of the film sealant after curing; at the same time, combined with epoxy-modified silica, the mechanical properties of the film sealant can be improved and the thermal expansion coefficient of the film sealant can be reduced.

[0031] In some possible embodiments, the model of the dispersant includes at least one of 1103 and 1401.

[0032] In some possible embodiments, the leveling agent includes at least one of BYK-333 and BYK-320.

[0033] The dispersant contains a high molecular block copolymer with filler affinity groups, which has good wettability and anti-settling ability, and can further improve the dispersibility of epoxy-modified silica in epoxy resin, thereby effectively reducing the viscosity of the system; the leveling agent can effectively reduce the tension of the film surface after printing and improve the leveling performance of the film sealant.

[0034] Based on a general inventive concept, see Figure 1 The present application also provides a method for preparing a film sealant with low warpage and high stability as described in the first aspect, the preparation method comprising: S1. Accurately weigh the raw material components, which specifically include, by mass percentage, epoxy-modified silica 80% to 84%, alicyclic epoxy resin 7% to 9%, anhydride curing agent 8% to 10%, dispersant 0.1% to 0.2%, core-shell structure additive 0.4% to 0.6%, leveling agent 0.2% to 0.3%, and carbon black 0.1% to 0.2%; S2, adding the weighed alicyclic epoxy resin and the core-shell structure auxiliary agent into a stirring cup, and stirring evenly by a first centrifugal stirrer to obtain a premix; S3, adding the weighed epoxy-modified silica, the anhydride curing agent, the dispersant, the leveling agent and the carbon black to the premix, and stirring evenly by a second centrifugal stirrer to obtain a first slurry; S4, transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; S5. The second slurry is vacuum degassed by a third centrifugal stirring to obtain a film sealing adhesive with low warpage and high stability.

[0035] The working parameters of the first centrifugal mixer include: stirring time of 30 to 60s, rotation of 800r / min, and revolution of 1000r / min; the working parameters of the second centrifugal mixer include: stirring time of 180 to 200s, rotation of 1200r / min, and revolution of 1500r / min; the working parameters of the three-roll grinder include: feeding gap of 100 to 120μm, and discharging gap of 70 to 90μm; the working parameters of the third centrifugal mixer include: vacuum degassing time of 60 to 80s, rotation of 800r / min, and revolution of 1000r / min.

[0036] Based on a general inventive concept, see Figure 2-3 The present invention also provides a chip packaging method, the chip packaging method comprising: (1) Obtain the wafer body; (2) copper pillars are arranged at equal intervals on the front surface of the wafer body, and semicircular grooves are cut on the front surface of the wafer body between two adjacent copper pillars to obtain a cut wafer; (3) coating the low-warpage and high-stability film sealant described in the first aspect on the front side of the cut wafer to obtain a packaged wafer; (4) grinding the front side of the packaging wafer to expose the copper pillar, and grinding the back side of the packaging wafer to expose the film sealant, thereby obtaining a ground wafer; (5) Coating the film sealant on the back side of the ground wafer, and continue cutting along the gaps cut by the semicircular grooves to obtain a plurality of well-packaged chips.

[0037] Specifically, the present application provides a chip packaging method, firstly, a plurality of copper pillars are arranged at intervals on the wafer body, and the wafer body is cut according to actual needs to form a semicircular groove to obtain a cut wafer; then, a film sealant is applied to the cut wafer to fill the semicircular groove to obtain a packaged wafer; then, the packaged wafer is front-ground and back-ground to obtain a ground wafer that meets the requirements; finally, the film sealant is applied to the back of the ground wafer away from the copper pillar, and after curing, it can be cut to obtain a plurality of intact chips. The film sealant prepared by the above-mentioned formula of the present application is used to encapsulate the grooves formed after the wafer is etched and half-cut in the early stage, so as to improve the protection effect of the wafer; later, the chip is encapsulated from the outside to improve the protection effect of the chip and extend the service life of the chip.

[0038] 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.

[0039] The components of the raw materials in Comparative Examples 1-4 and Examples 1-3 are shown in Table 1-2 below according to their mass fractions: Table 1 Distribution ratio of each group of raw materials in the comparative example The film sealants provided in Examples 1-3 and Comparative Examples 1-4 were tested for viscosity, wafer warpage and stability. The specific testing process is as follows: 1. Viscosity test: Use a digital display rotational viscometer for measurement. Test conditions: Select 14# rotor at 25℃, the speed is 20r / min; 2. Wafer warpage test: Take 12-14g of film sealant and apply it evenly on the wafer at room temperature. Place it in an oven at 70℃ / 1h+130℃ / 1h and then cool it down to room temperature naturally. Use a vernier caliper to measure the wafer warpage height. 3. Stability test: The prepared film sealing glue was stored at 25°C for 2h, 6h, 10h, and 12h, and its viscosity and wafer warpage height were tested respectively according to the above method.

[0040] The test results are shown in Table 2 below: Table 2 Test results From the above table, we can see that: (1) In Comparative Example 3, no core-shell structure additive was used. The initial viscosity of the prepared film sealant was low, but as time went on, the viscosity of the film sealant gradually increased, resulting in the inability to print and poor storage stability. At the same time, the wafer warpage of the cured film sealant was large, which was not conducive to chip packaging. (2) In Comparative Example 4, no dispersant was used, and the viscosity of the prepared film sealant was relatively high, and printing could not be performed; (3) In both Comparative Examples 1 and 2, core-shell structure additives and dispersants were added, but the addition ratios of epoxy-modified silica, alicyclic epoxy resin and methyl hexahydrophthalic anhydride were not within the range specified in the present application. As time went by, the viscosity of the prepared film sealant gradually increased, which could not meet the process requirements of film sealant printing. In addition, the film sealant had a large warpage after curing, which was not conducive to the long-term use of the chip. (4) The components of the raw materials in Examples 1-3 are within the range specified in the present application, and the prepared film sealant has a low viscosity. The viscosity does not change much over time, which can meet the requirements of the film sealant printing process. It also has high stability at room temperature and is suitable for low-temperature storage. After being stored at room temperature, the film sealant still has low warping after printing and curing.

[0041] In summary, the present application provides a low-warping and high-stability film sealant that can be stored at room temperature, and the performance of the film sealant does not change much after storage, and has high stability.

[0042] 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.

[0043] 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.

[0044] 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 warping and high stability film sealant, characterized in that: The film sealing glue comprises the following components by mass percentage: 80% to 84% of epoxy modified silicon dioxide, 7% to 9% of alicyclic epoxy resin, 8% to 10% of anhydride curing agent, 0.1% to 0.2% of dispersant, 0.4% to 0.6% of core-shell structure auxiliary agent, 0.2% to 0.3% of leveling agent, and 0.1% to 0.2% of carbon black.

2. The low warpage and high stability film sealant according to claim 1, characterized in that: The structural formula of the alicyclic epoxy resin is: 。 3. The low warpage and high stability film sealant according to claim 1, characterized in that: The shell of the core-shell structure auxiliary agent is methyl methacrylate, and the core of the core-shell structure auxiliary agent is BS resin.

4. The low warpage and high stability film sealant according to claim 1, characterized in that: The acid anhydride curing agent is methyl hexahydrophthalic anhydride.

5. The low warpage and high stability film sealant according to claim 1, characterized in that: The particle size of the epoxy-modified silica is 5-28 μm.

6. The low warpage and high stability film sealant according to claim 1, characterized in that: The model of the dispersant includes at least one of 1103 and 1401.

7. The low warpage and high stability film sealant according to claim 1, characterized in that: The leveling agent includes at least one of BYK-333 and BYK-320.

8. A method for preparing a film sealant with low warpage and high stability as claimed in any one of claims 1 to 7, characterized in that: The preparation method comprises: S1. Accurately weigh the raw material components, which specifically include, by mass percentage, epoxy-modified silica 80% to 84%, alicyclic epoxy resin 7% to 9%, anhydride curing agent 8% to 10%, dispersant 0.1% to 0.2%, core-shell structure additive 0.4% to 0.6%, leveling agent 0.2% to 0.3%, and carbon black 0.1% to 0.2%; S2, adding the weighed alicyclic epoxy resin and the core-shell structure auxiliary agent into a stirring cup, and stirring evenly by a first centrifugal stirrer to obtain a premix; S3, adding the weighed epoxy-modified silica, the anhydride curing agent, the dispersant, the leveling agent and the carbon black to the premix, and stirring evenly by a second centrifugal stirrer to obtain a first slurry; S4, transferring the first slurry to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; S5. The second slurry is vacuum degassed by a third centrifugal stirring to obtain a film sealing adhesive with low warpage and high stability.

9. The method for preparing a film sealant with low warpage and high stability according to claim 8, characterized in that: The working parameters of the first centrifugal mixer include: stirring time of 30 to 60 seconds, rotation of 800 r / min, revolution of 1000 r / min; The working parameters of the second centrifugal mixer include: stirring time of 180 to 200 seconds, rotation of 1200 r / min, and revolution of 1500 r / min; The working parameters of the three-roll mill include: the feed gap is 100-120 μm, the discharge gap is 70-90 μm; The working parameters of the third centrifugal mixer include: vacuum degassing time of 60 to 80 seconds, rotation of 800 r / min, and revolution of 1000 r / min.

10. A chip packaging method, characterized in that: The chip packaging method comprises: Obtaining a wafer body; Copper pillars are arranged at equal intervals on the front side of the wafer body, and semicircular grooves are cut on the front side of the wafer body between two adjacent copper pillars to obtain a cut wafer; Applying the low-warpage and high-stability film sealant according to any one of claims 1 to 7 on the front side of the diced wafer to obtain a packaged wafer; Grinding the front side of the packaging wafer to expose the copper pillar, and grinding the back side of the packaging wafer to expose the film sealant to obtain a ground wafer; The film sealant is coated on the back of the ground wafer, and cutting is continued along the gaps cut by the semicircular grooves to obtain a plurality of well-packaged chips.

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