Epoxy adhesive for multi-faceted packaging protection of chips, preparation method thereof and wafer packaging structure

Abstract

The application discloses a chip multi-surface packaging protection epoxy glue, a preparation method thereof and a wafer packaging structure. The chip multi-surface packaging protection epoxy glue comprises, based on 100% of the total weight, inorganic fillers 74-83%, a silicone oil modified alicyclic epoxy resin 4-10%, an acid anhydride curing agent 10-13%, a solvent 1-3%, a leveling agent 0.2-0.4%, a dispersing wetting agent 0.3-0.5%, a latent accelerator 0.2-0.3% and a colorant 0.1-0.2%. The wafer packaging structure comprises a chip and a packaging layer wrapping the chip, and the packaging layer is made of the epoxy glue. The epoxy glue has excellent filling property, silicon wafer adhesion and moisture resistance and heat resistance, can significantly relieve chip warping, and can be used as a printed film sealing glue for wafer packaging.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor packaging, and particularly relates to an epoxy adhesive for multi-face packaging protection of a chip, a preparation method thereof and a wafer packaging structure. BACKGROUND

[0002] In the field of chip packaging, an epoxy adhesive is often used to package the chip structure on multiple sides to protect the side edges of the chip, thereby enhancing the mechanical properties and reliability of the chip. At present, the multi-face packaging of the chip is often carried out in a wafer cutting process. For a specific process flow of wafer cutting, please refer to Figure 1 . The flow is as follows: a copper column 2 and a cutting groove 3 are made on a wafer 1, then an epoxy adhesive 4 is printed, the epoxy adhesive 4 covers the copper column 2 and fills the groove 3; after the epoxy adhesive 4 is cured, polishing is performed to expose the copper column 2; wafer back thinning is performed, and a UV debonding adhesive tape is attached to the front surface of the wafer 1 before the wafer back thinning to protect the front surface of the wafer 1; a back adhesive film 5 is printed on the back surface of the wafer 1, and then a single chip 6 is obtained by cutting along the groove 3, and the side edges of the obtained chip 6 are packaged by the epoxy adhesive 4.

[0003] However, the multi-face packaging of the chip structure also faces the following technical problems to be solved urgently: (1) the filling property of the epoxy adhesive 4 in the groove 3 is poor, and holes are easily formed during the curing process; during the wafer back thinning process, oxygen easily enters the holes, and under ultraviolet light irradiation, the oxygen reacts with the photoinitiator in the UV debonding adhesive tape, causing the UV debonding adhesive tape to become sticky and difficult to tear off; (2) the chip is warped due to the change in internal stress during the curing process of the epoxy adhesive 4. In addition, as an epoxy adhesive for multi-face packaging protection of a chip, the epoxy adhesive should also have low water absorption and moisture resistance to better protect the chip. SUMMARY

[0004] One of the purposes of the present application is to provide an epoxy adhesive for multi-face packaging protection of a chip, which comprises, based on 100% of the total weight: inorganic filler 74-83%, silicone oil modified alicyclic epoxy resin 4-10%, acid anhydride curing agent 10-13%, solvent 1-3%, leveling agent 0.2-0.4%, dispersing wetting agent 0.3-0.5%, latent accelerator 0.2-0.3%, and colorant 0.1-0.2%; wherein the chemical structural formula of the silicone oil modified alicyclic epoxy resin is

[0005] .

[0006] In the epoxy adhesive of the present application, the silicone oil modified alicyclic epoxy resin is used as the resin matrix to provide the adhesive property and mechanical property. The silicone oil modified alicyclic epoxy resin is prepared by introducing polysiloxane segments into the alicyclic epoxy resin. The introduction of the polysiloxane segments can significantly improve the filling property of the epoxy adhesive, thereby reducing or even avoiding the generation of holes; help to eliminate the internal stress of the cured product of the epoxy adhesive, thereby significantly improving the warping phenomenon of the chip; and also can significantly reduce the water absorption rate and significantly improve the adhesion and moisture resistance.

[0007] In some embodiments, the silicone oil modified alicyclic epoxy resin is prepared by the following method: the vinyl-containing alicyclic epoxy resin and the hydrogen-terminated silicone oil are subjected to a hydrosilylation reaction under the action of a platinum catalyst.

[0008] Further, the molar ratio of the vinyl-containing alicyclic epoxy resin to the hydrogen-terminated silicone oil is (2-2.5):1.

[0009] The above platinum catalyst is used in a catalytic amount, and further, the platinum catalyst is used in an amount of 0.5‰-1‰ of the mass of the alicyclic epoxy resin.

[0010] One specific embodiment of the above preparation method is as follows: first, a four-necked flask is charged with the vinyl-containing alicyclic epoxy resin and the platinum catalyst, and the temperature is raised to 80-90°C and maintained at this temperature for 0.5-1 h while stirring; then, the hydrogen-terminated silicone oil is added dropwise, and the reaction is carried out for 1.5-2 h; finally, the unreacted vinyl-containing alicyclic epoxy resin is removed by distillation under reduced pressure to obtain the silicone oil modified alicyclic epoxy resin.

[0011] In the epoxy adhesive of the present application, the inorganic filler is used to reduce the thermal expansion coefficient and moisture absorption of the cured product of the epoxy adhesive, and to enhance the modulus of the epoxy adhesive.

[0012] In some embodiments, the inorganic filler is selected from silica, preferably spherical silica, and preferably has a particle size of 2-28 μm.

[0013] In the epoxy adhesive of the present application, the curing agent is used to undergo a curing reaction with the resin matrix at a certain temperature to form a thermosetting compound with a three-dimensional network structure, and the accelerator is used to promote the curing reaction.

[0014] In the present application, the curing agent is selected from acid anhydride curing agents, such as curing agents with trade names YH 306, YH 307, etc.; and the accelerator is selected from latent accelerators, such as imidazole accelerators PN 23, PN 40, etc.

[0015] In the epoxy adhesive of the present application, the solvent is used to reduce the viscosity of the epoxy adhesive, and the leveling agent is used to reduce the surface tension of the epoxy adhesive, thereby improving the leveling property of the epoxy adhesive. The use of the solvent and the leveling agent is to make the epoxy adhesive printable on the wafer and fillable into the grooves.

[0016] In some embodiments, the solvent is selected from an ester solvent or ether ester solvent with a boiling point of 200-250℃, such as diethylene glycol butyl ether acetate, dipropylene glycol methyl ether acetate, or ethylene glycol phenyl ether acetate.

[0017] In some embodiments, the leveling agent is selected from a polyether-modified silicone leveling agent, such as BYK 333, BYK 320, etc.

[0018] In the epoxy adhesive of the present application, the dispersing wetting agent is used to promote the wet dispersion of the inorganic filler. In some embodiments, the dispersing wetting agent is selected from a polyether surfactant, such as SN-WET 984, SN-WET 990, etc.

[0019] The second object of the present application is to provide a preparation method of the above-mentioned epoxy adhesive for multi-surface packaging protection of chips, comprising:

[0020] (1) mixing and stirring the raw materials according to the ratio to obtain a slurry;

[0021] (2) dispersing the slurry using a three-roll mill;

[0022] (3) stirring and vacuum defoaming to obtain the epoxy adhesive product.

[0023] In some embodiments, step (1) uses a centrifugal mixer for mixing and stirring, with the parameters set as: 1200 r / min for rotation, 1500 r / min for revolution, and 170-320 s for stirring time.

[0024] In some embodiments, the feeding gap of the three-roll mill in step (2) is 60-95 μm, and the discharging gap is 45-60 μm.

[0025] In some embodiments, step (3) uses a centrifugal mixer for stirring and vacuum defoaming, with the parameters set as: 1200 r / min for rotation, 1500 r / min for revolution, and 70-90 s for stirring time.

[0026] The third object of the present application is to provide a wafer packaging structure, the structure of which can be seen from Figure 2 , comprising a chip and a packaging layer wrapping the chip, and the packaging layer is the above-mentioned epoxy adhesive.

[0027] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0028] The epoxy adhesive of the present application has excellent filling property, silicon wafer adhesion, and moisture resistance and heat resistance, can significantly alleviate the warping of the chip, and can be used as a printed film encapsulating adhesive for wafer packaging. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1A specific process flow for the current wafer cutting;

[0030] Figure 2 A schematic diagram of the wafer packaging structure in the embodiment;

[0031] Figure 3 An optical microscope photo of the epoxy glue in Example 1;

[0032] Figure 4 An optical microscope photo of the epoxy glue in Example 3;

[0033] Figure 5 An optical microscope photo of the epoxy glue in Comparative Example 1;

[0034] Figure 6 An optical microscope photo of the epoxy glue in Comparative Example 2;

[0035] Figure 7 An optical microscope photo of the epoxy glue in Comparative Example 3.

[0036] The figure mark: wafer 1, copper column 2, groove 3, epoxy glue 4, back glue film 5, chip 6, hole 7. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and beneficial effects of the present application more clear, the present application is further described in detail below in combination with embodiments.

[0038] The raw materials used in the examples and comparative examples are as follows:

[0039] Inorganic filler: spherical silica with a particle size of 2-28 μm purchased on the market;

[0040] Resin matrix: alicyclic epoxy resin Celloxide 2000 with a room temperature viscosity of 1.5 Pas;

[0041] Hydrogen-terminated silicone oil: room temperature viscosity of 2-3 mPa・s, hydrogen content of 0.5%, CAS: 70900-21-9;

[0042] Curing agent: acid anhydride curing agent YH 306, YH 307;

[0043] Solvent: diethylene glycol butyl ether acetate purchased on the market;

[0044] Leveling agent: polyether-modified silicone leveling agent BYK 333, BYK 320;

[0045] Dispersing wetting agent: polyether surfactant SN-WET 984, SN-WET 990;

[0046] Promoter: imidazole latent promoter PN 23, PN 40;

[0047] Colorant: commercially available carbon black.

[0048] The examples and comparisons provided in the present application are as follows:

[0049] Example 1

[0050] The raw materials and the amounts of each raw material of the epoxy adhesive in this example are as follows: spherical silica 74%, silicone oil modified alicyclic epoxy resin 10%, YH 306 13%, diethylene glycol butyl ether acetate 2%, BYK 333 0.3%, SN-WET 990 0.4%, PN 400.2%, carbon black 0.1%.

[0051] The silicone oil modified alicyclic epoxy resin above is prepared by the following method:

[0052] (1) Mix chloroplatinic acid and isopropanol in a mass ratio of 1:20 to obtain an isopropanol solution of chloroplatinic acid, wherein chloroplatinic acid is used as a catalyst for the addition reaction;

[0053] (2) Add Celloxide 2000 and the isopropanol solution of chloroplatinic acid to a four-necked flask, and heat to 85°C. After stirring for 0.8h, add the hydrogen-terminated silicone oil dropwise, which is completed within 0.5h, and then react for another 2h. The molar ratio of Celloxide 2000 to hydrogen-terminated silicone oil is 2:1, and the amount of chloroplatinic acid is 0.5‰ of the mass of Celloxide 2000;

[0054] (3) Remove the unreacted Celloxide 2000 by reduced pressure distillation to obtain the silicone oil modified alicyclic epoxy resin.

[0055] The preparation method of the epoxy adhesive in this example is as follows:

[0056] (1) Take each raw material according to the proportion and add it to a stirring cup. Use a centrifugal stirrer to stir to obtain a slurry. The rotation speed of the centrifugal stirrer is 1200 r / min and the revolution speed is 1500 r / min, and the stirring time is 200s.

[0057] (2) Use a three-roll mill to disperse the slurry. The feeding gap of the three-roll mill is 80μm and the discharging gap is 50μm.

[0058] (3) Use a centrifugal stirrer to vacuum defoam the dispersed slurry to obtain the epoxy adhesive product. The rotation speed of the centrifugal stirrer is 1200 r / min and the revolution speed is 1500 r / min, and the vacuum defoaming time is 80s.

[0059] Example 2

[0060] The raw materials and the amount of each raw material of the epoxy adhesive of the embodiment are as follows: spherical silica 76%, silicon oil modified alicyclic epoxy resin 9%, YH 307 12%, diethylene glycol butyl ether acetate 2%, BYK 320 0.3%, SN-WET 984 0.4%, PN 230.2%, carbon black 0.1%.

[0061] The silicon oil modified alicyclic epoxy resin is prepared by the following method:

[0062] (1) Chloroplatinic acid and isopropanol are mixed in a mass ratio of 1:20 to obtain an isopropanol solution of chloroplatinic acid, wherein chloroplatinic acid is used as a catalyst for the addition reaction.

[0063] (2) Celloxide 2000 and the isopropanol solution of chloroplatinic acid are added to a four-necked flask, and the temperature is raised to 80°C. After stirring for 0.5 h, hydrogen-terminated silicon oil is added dropwise, and the addition is completed within 0.5 h. Then, the reaction is continued for 2 h. The molar ratio of Celloxide 2000 to hydrogen-terminated silicon oil is 2.5:1, and the amount of chloroplatinic acid is 0.6‰ of the mass of Celloxide 2000.

[0064] (3) Unreacted Celloxide 2000 is removed by reduced pressure distillation to obtain the silicon oil modified alicyclic epoxy resin.

[0065] The preparation method of the epoxy adhesive of the embodiment is as follows:

[0066] (1) The raw materials are taken according to the proportion and added to a stirring cup. A centrifugal mixer is used for stirring to obtain a slurry. The rotation speed of the centrifugal mixer is 1200 r / min, and the rotation speed of the centrifugal mixer is 1500 r / min. The stirring time is 300 s.

[0067] (2) The slurry is dispersed by a three-roll mill. The feeding gap of the three-roll mill is 85 μm, and the discharging gap is 45 μm.

[0068] (3) The dispersed slurry is vacuum degassed by a centrifugal mixer to obtain the epoxy adhesive product. The rotation speed of the centrifugal mixer is 1200 r / min, and the rotation speed of the centrifugal mixer is 1500 r / min. The vacuum degassing time is 70 s.

[0069] Example 3

[0070] The raw materials and the amount of each raw material of the epoxy adhesive of the embodiment are as follows: spherical silica 78%, silicon oil modified alicyclic epoxy resin 8%, YH 306 11%, diethylene glycol butyl ether acetate 2%, BYK 333 0.3%, SN-WET 984 0.4%, PN 230.2%, carbon black 0.1%.

[0071] The silicone oil modified alicyclic epoxy resin is prepared by the following method:

[0072] (1) mixing chloroplatinic acid and isopropyl alcohol in a mass ratio of 1:20 to obtain an isopropyl alcohol solution of chloroplatinic acid, wherein the chloroplatinic acid acts as a catalyst for the addition reaction;

[0073] (2) adding Celloxide 2000 and the isopropyl alcohol solution of chloroplatinic acid into a four-necked flask, and heating to 90°C, then adding dropwise a terminal hydrogen-containing silicone oil after stirring for 1 h, the dropwise addition being completed within 0.5 h, and then reacting for another 2 h; wherein the molar ratio of Celloxide 2000 to the terminal hydrogen-containing silicone oil is 2.5:1, and the amount of chloroplatinic acid is 0.5‰ of the mass of Celloxide 2000;

[0074] (3) removing unreacted Celloxide 2000 by reduced pressure distillation to obtain the silicone oil modified alicyclic epoxy resin.

[0075] The preparation method of the epoxy adhesive of this embodiment is as follows:

[0076] (1) taking each raw material according to the proportion, adding into a stirring cup, and stirring to obtain a slurry by using a centrifugal stirrer, wherein the rotation speed of the centrifugal stirrer is 1200 r / min and 1500 r / min, and the stirring time is 250 s;

[0077] (2) dispersing the slurry by using a three-roll mill, wherein the feeding gap of the three-roll mill is 90 μm, and the discharging gap is 60 μm;

[0078] (3) vacuum defoaming the dispersed slurry by using a centrifugal stirrer to obtain the epoxy adhesive product, wherein the rotation speed of the centrifugal stirrer is 1200 r / min and 1500 r / min, and the vacuum defoaming time is 70 s.

[0079] Example 4

[0080] The raw materials and the amounts of each raw material of the epoxy adhesive of this embodiment are as follows: spherical silica 81%, silicone oil modified alicyclic epoxy resin 6%, YH 307 10%, diethylene glycol butyl ether acetate 2%, BYK 320 0.3%, SN-WET 990 0.4%, PN 400.2%, and carbon black 0.1%.

[0081] The silicone oil modified alicyclic epoxy resin is prepared by the following method:

[0082] (1) mixing chloroplatinic acid and isopropyl alcohol in a mass ratio of 1:20 to obtain an isopropyl alcohol solution of chloroplatinic acid, wherein the chloroplatinic acid acts as a catalyst for the addition reaction;

[0083] (2) Add Celloxide 2000 and chloroplatinic acid isopropanol solution into a four-necked flask, and heat to 85°C, then add end-hydrogen silicone oil dropwise after stirring for 0.5h, and the dropwise addition is completed within 0.5h, and then react for another 2h; wherein the molar ratio of the amount of Celloxide 2000 and end-hydrogen silicone oil is 2:1, and the amount of chloroplatinic acid is 1 ‰ of the mass of Celloxide 2000;

[0084] (3) Remove unreacted Celloxide 2000 by vacuum distillation to obtain a silicone oil modified alicyclic epoxy resin.

[0085] The preparation method of the epoxy adhesive of the embodiment is as follows:

[0086] (1) Take each raw material according to the proportion and add it into a stirring cup, and use a centrifugal stirrer to stir to obtain a slurry; the rotation speed of the centrifugal stirrer is 1200 r / min and 1500 r / min, and the stirring time is 280s;

[0087] (2) Disperse the slurry by using a three-roll mill, and the feeding gap of the three-roll mill is 70μm and the discharging gap is 55μm;

[0088] (3) Vacuum defoam the dispersed slurry by using a centrifugal stirrer to obtain an epoxy adhesive product, and the rotation speed of the centrifugal stirrer is 1200 r / min and 1500 r / min, and the vacuum defoaming time is 75s.

[0089] Example 5

[0090] The raw materials and the amount of each raw material of the epoxy adhesive of the embodiment are as follows: spherical silica 83%, silicone oil modified alicyclic epoxy resin 4%, YH 306 10%, diethylene glycol butyl ether acetate 2%, BYK 333 0.3%, SN-WET 984 0.4%, PN 230.2%, and carbon black 0.1%.

[0091] The silicone oil modified alicyclic epoxy resin is prepared by the following method:

[0092] (1) Mix chloroplatinic acid and isopropanol according to a mass ratio of 1:20 to obtain a chloroplatinic acid isopropanol solution, wherein the chloroplatinic acid is used as a catalyst for addition reaction;

[0093] (2) Add Celloxide 2000 and chloroplatinic acid isopropanol solution into a four-necked flask, and heat to 85°C, then add end-hydrogen silicone oil dropwise after stirring for 0.5h, and the dropwise addition is completed within 0.5h, and then react for another 2h; wherein the molar ratio of the amount of Celloxide 2000 and end-hydrogen silicone oil is 2:1, and the amount of chloroplatinic acid is 1 ‰ of the mass of Celloxide 2000;

[0094] (3) Vacuum distillation to remove unreacted Celloxide 2000 to obtain a silicone oil modified alicyclic epoxy resin.

[0095] The preparation method of the epoxy adhesive of the present example is as follows:

[0096] (1) The raw materials were taken according to the ratio and added to a stirring cup, and a centrifugal stirrer was used for stirring to obtain a slurry; the rotation speed of the centrifugal stirrer was 1200 r / min and the revolution speed was 1500 r / min, and the stirring time was 200 s;

[0097] (2) The slurry was dispersed by a three-roll mill, and the feeding gap of the three-roll mill was 80 pm and the discharging gap was 55 pm;

[0098] (3) The dispersed slurry was vacuum defoamed by a centrifugal stirrer to obtain an epoxy adhesive product, and the rotation speed of the centrifugal stirrer was 1200 r / min and the revolution speed was 1500 r / min, and the vacuum defoaming time was 75 s.

[0099] Comparative Example 1

[0100] The raw materials and the amount of each raw material of the epoxy adhesive of the present comparative example were as follows: spherical silica 78%, Celloxide 2000 8%, YH 306 11%, diethylene glycol butyl ether acetate 2%, BYK 333 0.3%, SN-WET 984 0.4%, PN 23 0.2%, and carbon black 0.1%.

[0101] The preparation method of the epoxy adhesive of the present comparative example was as follows:

[0102] (1) The raw materials were taken according to the ratio and added to a stirring cup, and a centrifugal stirrer was used for stirring to obtain a slurry; the rotation speed of the centrifugal stirrer was 1200 r / min and the revolution speed was 1500 r / min, and the stirring time was 200 s;

[0103] (2) The slurry was dispersed by a three-roll mill, and the feeding gap of the three-roll mill was 80 pm and the discharging gap was 55 pm;

[0104] (3) The dispersed slurry was vacuum defoamed by a centrifugal stirrer to obtain an epoxy adhesive product, and the rotation speed of the centrifugal stirrer was 1200 r / min and the revolution speed was 1500 r / min, and the vacuum defoaming time was 75 s.

[0105] Comparative Example 2

[0106] The raw materials and the amount of each raw material of the comparative example epoxy adhesive are as follows: spherical silica 86%, silicone oil modified alicyclic epoxy resin 3%, YH 306 8%, diethylene glycol butyl ether acetate 2%, BYK 333 0.3%, SN-WET 990 0.4%, PN 400.2%, carbon black 0.1%.

[0107] The silicone oil modified alicyclic epoxy resin is prepared by the following method:

[0108] (1) Mix chloroplatinic acid and isopropanol in a mass ratio of 1:20 to obtain an isopropanol solution of chloroplatinic acid, wherein chloroplatinic acid is used as a catalyst for the addition reaction;

[0109] (2) Add Celloxide 2000 and the isopropanol solution of chloroplatinic acid to a four-necked flask, and heat to 85°C. After stirring for 0.5h, add the terminal hydrogen-containing silicone oil dropwise, which is completed within 0.5h, and then react for another 1.5h. The molar ratio of Celloxide 2000 to terminal hydrogen-containing silicone oil is 2:1, and the amount of chloroplatinic acid is 0.5‰ of the mass of Celloxide 2000;

[0110] (3) Distill under reduced pressure to remove unreacted Celloxide 2000, and obtain the silicone oil modified alicyclic epoxy resin.

[0111] The preparation method of the comparative example epoxy adhesive is as follows:

[0112] (1) Take each raw material according to the proportion and add it to a stirring cup. Use a centrifugal mixer to stir to obtain a slurry. The rotation speed of the centrifugal mixer is 1200 r / min and the revolution speed is 1500 r / min, and the stirring time is 200s;

[0113] (2) Disperse the slurry using a three-roll mill, with an inlet gap of 80μm and an outlet gap of 55μm;

[0114] (3) Vacuum defoam the dispersed slurry using a centrifugal mixer, to obtain the epoxy adhesive product. The rotation speed of the centrifugal mixer is 1200 r / min and the revolution speed is 1500 r / min, and the vacuum defoaming time is 75s.

[0115] Comparative Example 3

[0116] The raw materials and the amount of each raw material of the comparative example epoxy adhesive are as follows: spherical silica 72%, silicone oil modified alicyclic epoxy resin 11%, YH 307 14%, diethylene glycol butyl ether acetate 2%, BYK 320 0.3%, SN-WET 984 0.4%, PN 230.2%, carbon black 0.1%.

[0117] The silicone oil modified alicyclic epoxy resin is prepared by the following method:

[0118] (1) mixing chloroplatinic acid and isopropyl alcohol in a mass ratio of 1:20 to obtain an isopropyl alcohol solution of chloroplatinic acid, wherein chloroplatinic acid is used as a catalyst for the addition reaction;

[0119] (2) adding Celloxide 2000 and the isopropyl alcohol solution of chloroplatinic acid into a four-necked flask, and heating to 85°C, and then adding dropwise the end hydrogen-containing silicone oil after stirring for 0.5h, which is completed within 0.5h, and then reacting for 1.5h; wherein the molar ratio of Celloxide 2000 to the end hydrogen-containing silicone oil is 2:1, and the amount of chloroplatinic acid is 0.8‰ of the mass of Celloxide 2000;

[0120] (3) removing the unreacted Celloxide 2000 by reduced pressure distillation to obtain the silicone oil modified alicyclic epoxy resin.

[0121] The preparation method of the epoxy adhesive of the comparative example is as follows:

[0122] (1) taking each raw material according to the proportion, adding into a stirring cup, and stirring by a centrifugal stirrer to obtain a slurry; the rotation speed of the centrifugal stirrer is 1200 r / min and 1500 r / min, and the stirring time is 200s;

[0123] (2) dispersing the slurry by a three-roll mill, and the feeding gap and the discharging gap of the three-roll mill are 80μm and 55μm, respectively;

[0124] (3) vacuum defoaming the dispersed slurry by a centrifugal stirrer to obtain the epoxy adhesive product, and the rotation speed of the centrifugal stirrer is 1200 r / min and 1500 r / min, and the vacuum defoaming time is 75s.

[0125] The detection method of each performance parameter of the epoxy adhesive of the above examples and the comparative example is as follows:

[0126] I. Viscosity:

[0127] The digital display rotary viscometer is used to test the viscosity at 25°C, the 14# rotor is selected, and the rotation speed is 20r / min.

[0128] II. Wafer warping:

[0129] About 12g of the vacuum defoamed epoxy adhesive is uniformly coated on an 8-inch wafer at room temperature, the wafer is placed in an oven at 180°C / 2h, and then naturally cooled to room temperature, and the height of wafer warping is measured by a vernier caliper.

[0130] III. Surface tension:

[0131] Ring method: A ring is placed on the surface of the glue at 25℃, and the maximum pulling force required to pull the ring off the glue is measured P The surface tension is calculated according to the formula wherein, represents the radius of the ring, represents a correction factor.

[0132] Four, the adhesion before and after Uhast

[0133] The measurement of the adhesion before Uhast is as follows: the epoxy glue is poured into a pudding mold with a diameter of 3 mm and a height of 2 mm, one end of the poured epoxy glue is in contact with a silicon wafer, the silicon wafer and the pudding mold are fixed, and the Uhast condition is 180℃ / 2h. After curing, the pudding mold is removed, and the cured epoxy glue sample is taken out. The adhesion between the cured epoxy glue sample and the silicon wafer is tested using a pusher, i.e. the adhesion before Uhast.

[0134] The measurement of the adhesion after Uhast is as follows: the epoxy glue is poured into a pudding mold with a diameter of 3 mm and a height of 2 mm, one end of the poured epoxy glue is in contact with a silicon wafer, the silicon wafer and the pudding mold are fixed, and the Uhast condition is 180℃ / 2h. After curing, the pudding mold is removed, and the cured epoxy glue sample is taken out. The cured epoxy glue sample is placed in the Uhast condition for 96h, and the adhesion between the cured epoxy glue sample and the silicon wafer is tested using a pusher, i.e. the adhesion after Uhast. The Uhast condition is: temperature 130℃, relative humidity 85% RH .

[0135] Five, water absorption rate:

[0136] The cured epoxy glue sample is placed in the Uhast condition for 96h, and then the water absorption rate of the sample is measured. The water absorption rate = (the mass of the sample after Uhast - the mass of the sample before Uhast) / the mass of the sample before Uhast. The curing condition is 180℃ / 2h; the Uhast condition is: temperature 130℃, relative humidity 85% RH .

[0137] Six, filling property:

[0138] Referring to Figure 1 , the epoxy glue is printed on the wafer 1 with copper pillars 2 and grooves 3 cut, so that the epoxy glue covers the copper pillars 2 and fills the grooves 3; after curing at 180℃ / 2h, the wafer 1 is polished from the back to the grooves 3, and whether there are holes at the grooves 3 under the optical microscope.

[0139] ​The test data of the epoxy adhesives of the examples and comparative examples are listed in Table 1 below. The resin matrix of Comparative Example 1 is unmodified alicyclic epoxy resin, and the properties of the epoxy adhesive of Comparative Example 1 are not good. The resin matrix of Comparative Examples 2-3 is silicone oil modified alicyclic epoxy resin, and the properties of the epoxy adhesives of Comparative Examples 2-3 are improved compared with those of Comparative Example 1, indicating that the silicone oil modification of the alicyclic epoxy resin improves the filling property, wafer warping phenomenon, adhesion, water absorption and moisture resistance, but the improvement is not obvious. However, when the resin matrix is silicone oil modified alicyclic epoxy resin and the specific amount of each raw material is met (see Examples 1-5), the wafer warping phenomenon can be significantly improved; the adhesion to the silicon wafer is significantly enhanced, and the high adhesion can still be maintained after moisture and heat treatment; the water absorption is significantly reduced; the epoxy adhesive has excellent filling property, and there is no hole in the epoxy adhesive in the groove, as shown in Figures 3-4 However, the epoxy adhesives of Comparative Examples 1-3 all have obvious holes after filling the grooves, as shown in Figures 5-7 Although the epoxy adhesives of Comparative Examples 1-3 all have obvious holes, the epoxy adhesives using silicone oil modified alicyclic epoxy resin (see Comparative Examples 2-3) have relatively fewer holes.

[0140] The applicant believes that the mechanism by which the epoxy adhesive of the present application can produce the above significant technical effects is that the silicone oil modified alicyclic epoxy resin introduces polysiloxane segments into the epoxy resin. The flexible Si-O bond in the polysiloxane segments makes the polymer segments easy to rotate, which helps to eliminate the internal stress of the epoxy resin cured product and improve the wafer warping phenomenon. The introduction of Si-O bond reduces the C-C bond in alicyclic epoxy resin. Since the bond energy of Si-O bond is much higher than that of C-C bond, it helps to improve the heat resistance of the epoxy resin cured product. The low surface energy and high hydrophobicity of Si-O bond help to reduce the polarity of the epoxy resin cured product, thereby reducing its surface tension, which helps to improve the filling property and moisture resistance of the epoxy adhesive. In addition, the use of specific formulation with appropriate curing agent and other additives can significantly improve the wafer warping phenomenon and significantly enhance the adhesion, filling property, moisture resistance and other properties of the epoxy adhesive.

[0141] Table 1 Test data of the epoxy adhesives of the examples and comparative examples

[0142]

[0143] The above examples are only for clearly illustrating the examples made, and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can also be made by those skilled in the art, and here it is not necessary or impossible to exhaust all the embodiments, so the changes or variations deduced are still within the protection scope of the present application.

Claims

1. An epoxy adhesive for chip multi-face package protection, characterized in that: it comprises, based on the total weight of 100%, 74-83% of inorganic filler, 4-10% of silicone oil modified alicyclic epoxy resin, 10-13% of acid anhydride curing agent, 1-3% of solvent, 0.2-0.4% of leveling agent, 0.3-0.5% of dispersing wetting agent, 0.2-0.3% of latent accelerator, and 0.1-0.2% of colorant; the chemical structural formula of the silicone oil modified alicyclic epoxy resin is as follows: the inorganic filler is selected from silica.

2. The epoxy adhesive for chip multi-face package protection according to claim 1, characterized in that: the silicone oil modified alicyclic epoxy resin is prepared by the following method: alicyclic epoxy resin containing vinyl and hydrogen-terminated silicone oil are subjected to a silicon-hydrogen addition reaction under the catalysis of platinum.

3. The epoxy adhesive for chip multi-face package protection according to claim 2, characterized in that: the molar ratio of the alicyclic epoxy resin containing vinyl and the hydrogen-terminated silicone oil is (2-2.5):

1. ； 4. The epoxy adhesive for chip multi-face package protection according to claim 1, characterized in that: the solvent is selected from ester or ether ester solvents with a boiling point of 200-250°C.

5. The epoxy adhesive for chip multi-face package protection according to claim 1, characterized in that: the leveling agent is selected from polyether modified silicone leveling agents.

6. The epoxy adhesive for chip multi-face package protection according to claim 1, characterized in that: the dispersing wetting agent is selected from polyether surfactants.

7. The epoxy adhesive for chip multi-face package protection according to claim 1, characterized in that: the latent accelerator is selected from imidazole latent accelerators. The preparation method comprises the following steps: (1) mixing and stirring the raw materials according to the proportion to obtain a slurry; (2) dispersing the slurry by using a three-roll mill; (3) stirring and vacuum defoaming to obtain the epoxy adhesive product. The chip and the packaging layer wrapping the chip, wherein the packaging layer material is the epoxy adhesive according to any one of claims 1-7. ​ ​ ​ ​ 8. A method for preparing the epoxy adhesive for multi-sided encapsulation protection of chips according to any one of claims 1 to 7, characterized in that, ​ ​ ​ ​ 9. A wafer package structure, characterized by, ​ ​

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