High-reliability printing state film sealing adhesive, preparation method thereof and chip packaging method

Abstract

The invention provides a high-reliability printing state film sealing adhesive, a preparation method thereof and a chip packaging method. The printing state film sealing adhesive comprises the following components in percentage by mass: 4-6% of liquid epoxy resin, 83-88% of modified silicon dioxide, 3-5% of an amine curing agent, 3-4% of an epoxy active diluent, 0.2-0.4% of an adhesion promoter, 1-2% of a solvent and 0.1-0.2% of carbon black. By adjusting the proportion of the liquid epoxy resin, the modified silicon dioxide and the amine curing agent and combining the epoxy reactive diluent, the adhesion promoter and the solvent, the viscosity of the system is reduced, the service life of the film sealing adhesive is prolonged, meanwhile, the warping degree after curing is reduced, and the reliability of chip / wafer packaging is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of chip packaging, and in particular relates to a high-reliability printed film sealing glue and 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, printed film sealant has the characteristics of protecting circuits from external environmental influences. However, the existing film sealant has a high degree of warping after curing and is easy to absorb water, thus affecting the service life of the chip.

[0004] It can be seen that how to provide a highly reliable printed film sealant and reduce the warping and water absorption of the printed film sealant by adjusting the ratio between liquid epoxy resin, modified silica and amine curing agent, thereby improving the reliability of chip packaging is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] The object of the present invention is to provide a highly reliable printed film sealant 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 highly reliable printed film sealant, wherein the printed film sealant comprises the following components by mass percentage: 4% to 6% of liquid epoxy resin, 83% to 88% of modified silica, 3% to 5% of amine curing agent, 3% to 4% of epoxy reactive diluent, 0.2% to 0.4% of adhesion promoter, 1% to 2% of solvent, and 0.1% to 0.2% of carbon black.

[0007] In the first aspect, the modified silica is prepared by: preparing a coupling agent solution, wherein the coupling agent solution is a mixture of a coupling agent, anhydrous ethanol and water in a volume ratio of 1:2:1; preparing a modifying aid, wherein the modifying aid is a mixture of ammonia water and water in a volume ratio of 1:3; adding the coupling agent solution and the modifying aid to silica to obtain a mixture, wherein the amount of the coupling agent added is 0.5% of the mass of the silica, and the amount of the modifying aid added is 1.0‰ of the mass of the silica; adding the mixture to a ball mill for ball milling for 60 minutes to obtain modified silica.

[0008] In the first aspect, the coupling agent is a silane coupling agent and a titanate coupling agent, and the mass ratio of the silane coupling agent to the titanate coupling agent is 1:1; the silica is spherical silica, and the particle size of the spherical silica is 6-29 μm.

[0009] In the first aspect, the liquid epoxy resin is bisphenol A epoxy resin.

[0010] In the first aspect, the amine curing agent includes at least one of epoxy-modified fatty amines and phenolic-modified amines.

[0011] In the first aspect, the solvent is diethylene glycol monoethyl ether acetate.

[0012] In the first aspect, the epoxy reactive diluent is of JRD-150 or JRD-160; the adhesion promoter is of Silquest A-187 or OFS 6040.

[0013] The second aspect of the present invention provides a method for preparing a highly reliable printed film sealant as described in the first aspect, the preparation method comprising: S1, preparing modified silica; 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: liquid epoxy resin 4% to 6%, modified silica 83% to 88%, amine curing agent 3% to 5%, epoxy reactive diluent 3% to 4%, adhesion promoter 0.2% to 0.4%, solvent 1% to 2%, and carbon black 0.1% to 0.2%; S3, transferring the first slurry to a three-roll grinder for dispersion treatment to obtain a uniformly dispersed second slurry; S4, vacuum degassing the second slurry by a second centrifugal stirrer to obtain a printed film sealant.

[0014] In the second aspect, the preparation method of the modified silica includes: preparing a coupling agent solution, wherein the coupling agent solution is a mixture of a coupling agent, anhydrous ethanol and water in a volume ratio of 1:2:1, the coupling agent is a silane coupling agent and a titanate coupling agent, and the mass ratio of the silane coupling agent to the titanate coupling agent is 1:1; preparing a modifying agent, wherein the modifying agent is a mixture of ammonia water and water in a volume ratio of 1:3; adding the coupling agent solution and the modifying agent to silica to obtain a mixture, wherein the addition amount of the coupling agent is 0.5% of the mass of the silica, and the addition amount of the modifying agent is 1.0‰ of the mass of the silica; adding the mixture to a ball mill for ball milling, and the ball milling time is 60 minutes to obtain modified silica.

[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 high-reliability printed film sealant 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 printed film sealant to obtain a ground wafer; applying the printed film sealant 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 invention provides a high-reliability printed film sealant, which comprises the following components by mass percentage: 4% to 6% of liquid epoxy resin, 83% to 88% of modified silicon dioxide, 3% to 5% of amine curing agent, 3% to 4% of epoxy reactive diluent, 0.2% to 0.4% of adhesion promoter, 1% to 2% of solvent, and 0.1% to 0.2% of carbon black; the modified silicon dioxide can be uniformly dispersed in the low-viscosity liquid epoxy resin, and combined with the amine curing agent to improve the toughness of the film sealant and reduce the warpage of the film sealant after printing and curing; the epoxy reactive diluent is added to further reduce the viscosity of the system, so that the film sealant has a flat film surface during the printing process; and the adhesion promoter is added to improve the bonding strength between the chip / wafer and the film sealant, thereby improving the reliability of chip packaging. The present invention adjusts the ratio of liquid epoxy resin, modified silicon dioxide and amine curing agent, and combines epoxy reactive diluent, adhesion promoter and solvent to reduce the viscosity of the system, thereby extending the service life of the film sealant, reducing the warpage after curing, and improving the reliability of chip / 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 A flow chart of a method for preparing a highly reliable printed film sealant provided by the present invention; Figure 2 A chip packaging method provided by the present invention Figure 1 ; Figure 3 A chip packaging method provided by the present invention Figure 2 ; Figure 4 The SEM image of Example 1 provided by the present invention; Figure 5 This is the SEM image of Comparative Example 1 provided by the present invention. 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 highly reliable printed film sealant, which comprises the following components by mass percentage: 4% to 6% liquid epoxy resin, 83% to 88% modified silicon dioxide, 3% to 5% amine curing agent, 3% to 4% epoxy reactive diluent, 0.2% to 0.4% adhesion promoter, 1% to 2% solvent, and 0.1% to 0.2% carbon black.

[0023] Specifically, the present invention provides a high-reliability printed film sealant, which includes the following components in mass percentage: 4% to 6% liquid epoxy resin, 83% to 88% modified silicon dioxide, 3% to 5% amine curing agent, 3% to 4% epoxy reactive diluent, 0.2% to 0.4% adhesion promoter, 1% to 2% solvent, and 0.1% to 0.2% carbon black; the modified silicon dioxide can be evenly dispersed in the low-viscosity liquid epoxy resin, and combined with the amine curing agent to improve the toughness of the film sealant and reduce the warping of the film sealant after printing and curing, and the epoxy reactive diluent is added to further reduce the viscosity of the system, so that the film sealant has a flat film surface during the printing process, and the adhesion promoter is added to improve the bonding strength between the chip / wafer and the film sealant, thereby improving the reliability of chip packaging. The present invention adjusts the ratio of liquid epoxy resin, modified silicon dioxide and amine curing agent, and combines epoxy reactive diluent, adhesion promoter and solvent to reduce the viscosity of the system, thereby extending the service life of the film sealant, reducing the warpage after curing, and improving the reliability of chip / wafer packaging.

[0024] In some possible embodiments, the modified silica is prepared by: preparing a coupling agent solution, wherein the coupling agent solution is a mixture of a coupling agent, anhydrous ethanol and water in a volume ratio of 1:2:1; preparing a modification aid, wherein the modification aid is a mixture of ammonia water and water in a volume ratio of 1:3; adding the coupling agent solution and the modification aid to silica to obtain a mixture, wherein the amount of the coupling agent added is 0.5% of the mass of the silica, and the amount of the modification aid added is 1.0‰ of the mass of the silica; adding the mixture to a ball mill for ball milling for 60 minutes to obtain modified silica.

[0025] In some possible embodiments, the coupling agent is a silane coupling agent and a titanate coupling agent, and the mass ratio of the silane coupling agent to the titanate coupling agent is 1:1; the silica is spherical silica, and the particle size of the spherical silica is 6-29 μm.

[0026] This is because the silicon dioxide modified by the silane coupling agent and the titanate coupling agent has better dispersibility in the epoxy resin, and there is no obvious agglomeration phenomenon during the film sealant printing process, which makes the film surface smooth after printing, which is beneficial to improve the reliability of chip / wafer packaging. In addition, the proportion of modified silicon dioxide in this application is relatively high, which can effectively reduce the thermal expansion coefficient and water absorption of the film sealant and enhance the modulus of the film sealant.

[0027] In some possible embodiments, the liquid epoxy resin is bisphenol A epoxy resin.

[0028] Those skilled in the art will appreciate that the bisphenol A epoxy resin selected as the liquid epoxy resin of the present application has a lower viscosity and excellent bonding properties, is conducive to the dispersion of modified silicon dioxide, and is also conducive to printing. In a specific embodiment, the liquid bisphenol A epoxy resin can be selected from NPEL128 or KE-8120.

[0029] In some possible embodiments, the amine curing agent includes at least one of epoxy-modified fatty amine and phenolic-modified amine.

[0030] In order to improve the toughness of the film sealant and reduce the viscosity of the film sealant, the modified amine curing agent is selected in the present application. The fatty amine is modified by an epoxy compound, which can reduce the viscosity of the curing agent, so that the curing agent structure has more active hydrogen and ether bonds, can be cured at room temperature, and has good toughness and strength after curing with epoxy resin; the amine is modified by a phenolic compound, so that the curing agent has more active groups such as phenolic hydroxyl, primary amino, secondary amino, etc., the curing rate is fast, and it has good heat resistance after curing with epoxy resin. In a specific embodiment, the epoxy-modified fatty amine can be selected as CYDHD-593, and the phenolic modified amine can be selected as T31.

[0031] In some possible embodiments, the solvent is diethylene glycol monoethyl ether acetate.

[0032] In some possible embodiments, the epoxy reactive diluent is of model JRD-150 or JRD-160; the adhesion promoter is of model Silquest A-187 or OFS 6040.

[0033] Those skilled in the art can understand that selecting diethylene glycol monoethyl ether acetate as a solvent can further reduce the viscosity of the film sealant and extend the service life; adding an epoxy reactive diluent can improve the compatibility between the raw material components, reduce the viscosity of the system, and improve the toughness of the film sealant; an adhesion promoter can increase the adhesion between the film sealant and the chip / wafer and improve the reliability of its packaging.

[0034] Based on a general inventive concept, see Figure 1 The present application also provides a method for preparing a high-reliability printed film sealant as described in the first aspect, the preparation method comprising: S1. preparing modified silicon dioxide; S2. Add each component into a stirring cup according to their respective mass percentages, mix them evenly by a first centrifugal stirrer, and obtain a first slurry, wherein the mass percentages of the components specifically include: 4% to 6% of liquid epoxy resin, 83% to 88% of modified silicon dioxide, 3% to 5% of amine curing agent, 3% to 4% of epoxy reactive diluent, 0.2% to 0.4% of adhesion promoter, 1% to 2% of solvent, and 0.1% to 0.2% of carbon black; wherein the stirring time is 180 to 200 seconds, the rotation is 1050 r / min, and the revolution is 1500 r / min; S3, the first slurry is transferred to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; wherein the feed gap of the three rollers is 100-120 μm, and the discharge gap is 75-90 μm; S4. The second slurry is vacuum degassed by a second centrifugal mixer to obtain a printed film sealant; wherein the vacuum degassed time is 60 to 80 seconds, the rotation speed is 700 r / min, and the revolution speed is 1000 r / min.

[0035] The preparation method of the modified silica comprises: preparing a coupling agent solution, wherein the coupling agent solution is prepared by mixing a coupling agent, anhydrous ethanol and water in a volume ratio of 1:2:1, wherein the coupling agent is a silane coupling agent and a titanate coupling agent, and the mass ratio of the silane coupling agent to the titanate coupling agent is 1:1; preparing a modifying aid, wherein the modifying aid is prepared by mixing ammonia water and water in a volume ratio of 1:3; adding the coupling agent solution and the modifying aid to silica to obtain a mixture, wherein the added amount of the coupling agent is 0.5% of the mass of the silica, and the added amount of the modifying aid is 1.0‰ of the mass of the silica; adding the mixture into a ball mill for ball milling, and the ball milling time is 60 minutes to obtain the modified silica.

[0036] Based on a general inventive concept, such as Figure 2-3 As shown, the present application 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) applying the high-reliability printed 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 printed film sealant to obtain a ground wafer; (5) Coating the printed 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 printed film sealant is applied to the cut wafer to fill the semicircular groove to obtain a packaged wafer; then, the packaged wafer is front-grinded and back-grinded to obtain a ground wafer that meets the requirements; finally, a printed 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 printed film sealant provided by the present application is used to encapsulate the chip / wafer, which has the advantages of flat film surface, low warping, low water absorption, etc., thereby improving the reliability of the chip / wafer packaging.

[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 1-3 and Examples 1-3 are shown in Table 1 below according to their mass fractions: Table 1 Distribution ratio of each group of raw materials in the comparative example The viscosity, wafer warpage and water absorption rate of the printed film sealant provided in Examples 1-3 and Comparative Examples 1-3 were tested. The specific test 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 13-15g of printed film sealant and evenly apply it on the wafer at room temperature. Place it in an oven at 60℃ / 1h+150℃ / 1h and then cool it down to room temperature naturally. Use a vernier caliper to measure the wafer warpage height. 3. Water absorption test: Take the printed film sealant specimen cured at 150℃ / 2h, and test its water absorption under the conditions of 130℃ and 85%RH for 96 hours; 4. SEM test: Observe the completely cured samples under an ultrasonic scanning microscope to see if there is any filler agglomeration.

[0040] The test results are shown in Table 2 below: Table 2 Test results From the above table, we can see that: (1) Comparative Example 1 uses unmodified silica, and the prepared film sealant has higher viscosity, warpage and water absorption rate. Agglomeration phenomenon (such as Figure 5 shown); (2) Although modified silica was added in Comparative Examples 2 and 3, the amount added exceeded the range specified in the present application, and the amount added of liquid bisphenol A epoxy resin and modified amine curing agent also exceeded the range specified in the present application. The viscosity and warpage of the prepared film sealant decreased significantly, but it still had a high water absorption rate and did not meet the requirements of chip / wafer printing packaging; (3) The raw material components in Examples 1-3 are within the range specified in the present application, and the prepared film sealant has a lower viscosity, and after printing and curing, the wafer warpage and water absorption rate can be significantly reduced, so that the chip / wafer packaging has a higher reliability. In particular, the film sealant prepared in Example 1 is observed under an ultrasonic scanning microscope, and no agglomeration phenomenon (such as Figure 4 as shown).

[0041] In summary, the present application provides a highly reliable printed film sealant, in which the silicon dioxide modified by the silane coupling agent and the titanate coupling agent has excellent dispersibility in the epoxy resin, is not easy to agglomerate during the printing process, reduces the viscosity and thermal expansion coefficient of the system, and improves the strength of the film sealant. At the same time, the liquid bisphenol A epoxy resin, the modified amine curing agent with more active groups, the epoxy active diluent, the adhesion promoter and the solvent are combined to jointly reduce the viscosity of the system and extend the service life, so that the film sealant prepared by the formula ratio of the present application has a flat film surface and no warping, low water absorption, and high packaging reliability during the chip / wafer printing packaging process.

[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 high-reliability printed film sealant, characterized in that: The printed film sealant comprises the following components by mass percentage: 4% to 6% of liquid epoxy resin, 83% to 88% of modified silicon dioxide, 3% to 5% of amine curing agent, 3% to 4% of epoxy reactive diluent, 0.2% to 0.4% of adhesion promoter, 1% to 2% of solvent, and 0.1% to 0.2% of carbon black.

2. The high-reliability printed film sealant according to claim 1, characterized in that: The modified silica is prepared in the following manner: preparing a coupling agent solution, wherein the coupling agent solution is prepared by mixing a coupling agent, anhydrous ethanol and water in a volume ratio of 1:2:1; preparing a modifying aid, wherein the modifying aid is prepared by mixing ammonia water and water in a volume ratio of 1:3; adding the coupling agent solution and the modifying aid to silica to obtain a mixture, wherein the added amount of the coupling agent is 0.5% of the mass of the silica, and the added amount of the modifying aid is 1.0‰ of the mass of the silica; adding the mixture into a ball mill for ball milling, and the ball milling time is 60 minutes to obtain the modified silica.

3. The high-reliability printed film sealant according to claim 2, characterized in that: The coupling agent is a silane coupling agent and a titanate coupling agent, and the mass ratio of the silane coupling agent to the titanate coupling agent is 1:1; The silicon dioxide is spherical silicon dioxide, and the particle size of the spherical silicon dioxide is 6-29 μm.

4. The high-reliability printed film sealant according to claim 1, characterized in that: The liquid epoxy resin is bisphenol A epoxy resin.

5. The high-reliability printed film sealant according to claim 1, characterized in that: The amine curing agent includes at least one of epoxy-modified fatty amine and phenolic-modified amine.

6. The high-reliability printed film sealant according to claim 1, characterized in that: The solvent is diethylene glycol monoethyl ether acetate.

7. The high-reliability printed film sealant according to claim 1, characterized in that: The model of the epoxy reactive diluent is JRD-150 or JRD-160; the model of the adhesion promoter is Silquest A-187 or OFS 6040.

8. A method for preparing a high-reliability printed film sealant as claimed in any one of claims 1 to 7, characterized in that: The preparation method comprises: S1. preparing modified silicon dioxide; S2, 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: liquid epoxy resin 4% to 6%, modified silicon dioxide 83% to 88%, amine curing agent 3% to 5%, epoxy reactive diluent 3% to 4%, adhesion promoter 0.2% to 0.4%, solvent 1% to 2%, and carbon black 0.1% to 0.2%; S3, the first slurry is transferred to a three-roll mill for dispersion treatment to obtain a uniformly dispersed second slurry; S4. Vacuum degassing the second slurry by a second centrifugal mixer to obtain a printed film sealant.

9. The method for preparing a printed film sealant with high reliability according to claim 8, characterized in that: The preparation method of the modified silicon dioxide comprises: A coupling agent solution is prepared, wherein the coupling agent solution is prepared by mixing a coupling agent, anhydrous ethanol and water in a volume ratio of 1:2:1, wherein the coupling agent is a silane coupling agent and a titanate coupling agent, and the mass ratio of the silane coupling agent to the titanate coupling agent is 1:1; preparing a modification aid, wherein the modification aid is a mixture of ammonia water and water in a volume ratio of 1:3; Adding the coupling agent solution and the modifying agent to silicon dioxide to obtain a mixture, wherein the coupling agent is added in an amount of 0.5% of the mass of the silicon dioxide, and the modifying agent is added in an amount of 1.0‰ of the mass of the silicon dioxide; The mixture was added into a ball mill for ball milling for 60 min to obtain modified silicon dioxide.

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 high-reliability printed 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 packaged wafer to expose the copper pillar, and grinding the back side of the packaged wafer to expose the printed film sealant to obtain a ground wafer; The printed 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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