Method for producing ETFE film for semiconductor packaging

Abstract

The application belongs to the technical field of ETFE film preparation, and particularly relates to a preparation method of ETFE film for semiconductor packaging. The preparation method of the ETFE film for semiconductor packaging comprises the following steps: (1) preparation of tetrafluoroethylene-glycidyl methacrylate copolymer; (2) pretreatment of ETFE resin; (3) silanization treatment of nano-composite filler; (4) preparation of ETFE film; and (5) post-treatment of the ETFE film to obtain the ETFE film for semiconductor packaging. The ETFE film for semiconductor packaging prepared by the preparation method has excellent mechanical properties and wear resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ETFE film preparation, and particularly relates to a preparation method of ETFE film for semiconductor packaging. BACKGROUND

[0002] Film materials commonly used in the field of semiconductor packaging include organic silicon coating film, ordinary polyester film, PTFE film and ETFE film. However, the organic silicon coating film has defects such as silicon migration risk, insufficient heat resistance, easy deformation and short service life. The ordinary polyester film has poor heat resistance, a large coefficient of thermal expansion, easy adhesion to packaging materials and is not suitable for high-temperature processes. The PTFE film has poor processability, difficulty in controlling thickness uniformity and poor adhesion to molds.

[0003] ETFE film gradually emerges in the field of semiconductor packaging due to its high thermal stability, ultra-low surface energy, mechanical properties, chemical inertness and electrical insulation. ETFE film is applied to packaging substrates, isolation layers, sealing materials and protective layers in semiconductor packaging. Related technologies include film forming, cutting, assembling and packaging processes. ETFE film can be used as a film material for semiconductor packaging film. Improving the wear resistance and scratch resistance of ETFE film can improve the performance and reliability of semiconductor devices. For example, additives or fillers with higher wear resistance, such as nanoparticles and carbon nanotubes, can be introduced. Surface treatment technologies such as plasma treatment and chemical modification can also be used to improve the chemical properties and morphology of the ETFE film surface. Nanotechnology can be used to prepare ETFE films with special surface structures, such as nanostructured surfaces and nanoporous structures. These studies can help solve the friction and scratch problems that semiconductor devices may encounter in practical applications, and promote the sustainable development and progress of the semiconductor industry.

[0004] Currently, ETFE film used in the field of semiconductor packaging still has insufficient strength and wear resistance, which is difficult to meet the dual requirements of high cleanliness and high wear resistance for packaging processes. Although SiO2 or carbon nanotubes are added as fillers to improve the performance of ETFE, there are still problems such as filler agglomeration due to low surface energy, no chemical bonding at the interface, and surface migration failure after high-temperature treatment. Therefore, it is necessary to explore a new ETFE film for semiconductor packaging. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of ETFE film for semiconductor packaging. The ETFE film prepared by the method has good tensile strength and wear resistance.

[0006] The preparation method of ETFE film for semiconductor packaging according to the present application comprises the following steps:

[0007] (1) Preparation of tetrafluoroethylene-glycidyl methacrylate copolymer

[0008] ① Deionized water, 4,8-dioxa-3H-perfluorononanoic acid ammonium and potassium persulfate were added into a high-pressure reactor, the high-pressure reactor was sealed, the air in the reactor was replaced with nitrogen for 3 times, then tetrafluoroethylene was introduced until the pressure in the reactor reached 0.2 MPa, the nitrogen was replaced for 2 times, and the reactor was emptied to normal pressure after each replacement, then tetrafluoroethylene was continuously introduced until the pressure in the reactor reached 2.5 MPa, glycidyl methacrylate was pressed into the high-pressure reactor with nitrogen within 5 min, the temperature was raised to 55-58°C for stirring reaction, and tetrafluoroethylene was added to maintain the pressure in the reactor at 2.5 MPa during the reaction; when the reaction was carried out for 3 h, methanol was added into the high-pressure reactor as a polymerization inhibitor, the heating was stopped when the reaction was carried out for 3.2-3.4 h, and the temperature was lowered to room temperature, thereby obtaining a tetrafluoroethylene-glycidyl methacrylate copolymer emulsion;

[0009] ② The tetrafluoroethylene-glycidyl methacrylate copolymer emulsion was added with a coagulant, and the copolymer was precipitated by stirring, then washed and dried, thereby obtaining a tetrafluoroethylene-glycidyl methacrylate copolymer;

[0010] (2) Pretreatment of ETFE resin

[0011] The ETFE resin was heated at 150°C in an air atmosphere for 2.5 h, and naturally cooled, thereby obtaining a pretreated ETFE resin;

[0012] (3) Silanization treatment of nanocomposite filler

[0013] ① The halloysite nanotube, nanometer lanthanum fluoride and nanometer zirconium silicate were dissolved in deionized water, then ammonia was added to adjust the pH value of the system to 9.0, and ultrasonic treatment was carried out at 33-35°C for 30 min;

[0014] ② The 1H,1H,2H,2H-perfluorodecyltriethoxysilane solution was added dropwise into the above reaction system, and reflux reaction was carried out at 81-83°C for 4 h, then the reaction system was filtered, washed, dried and sieved, thereby obtaining a silanized nanocomposite filler;

[0015] (4) The pretreated ETFE resin, the silanized nanocomposite filler and the tetrafluoroethylene-glycidyl methacrylate copolymer were uniformly mixed, then put into a twin-screw extruder for melt blending, thereby obtaining a blend, the blend was extruded into a sheet through a T-shaped die, and finally longitudinally stretched, transversely stretched and heat set, thereby obtaining an ETFE film;

[0016] (5) The ETFE film prepared in step (4) was post-treated, thereby obtaining an ETFE film for semiconductor packaging.

[0017] The mass of 4,8-dioxa-3H-perfluorononanoic acid ammonium in step (1) ① accounts for 0.4% of the mass sum of deionized water, 4,8-dioxa-3H-perfluorononanoic acid ammonium, potassium persulfate, tetrafluoroethylene and glycidyl methacrylate.

[0018] The mass of potassium persulfate in step (1) ① accounts for 0.2-0.23% of the mass sum of tetrafluoroethylene and glycidyl methacrylate.

[0019] The molar ratio of the total amount of tetrafluoroethylene to glycidyl methacrylate in step (1) ① is 10-11:1.

[0020] The mass of deionized water in step (1) ① is 3 times of the mass sum of tetrafluoroethylene and glycidyl methacrylate.

[0021] The mass of methanol polymerization inhibitor in step (1) ① accounts for 0.17% of the mass sum of tetrafluoroethylene and glycidyl methacrylate.

[0022] The coagulant in step (1) ② is saturated sodium chloride solution, and the volume of the coagulant added is 5% of the volume of tetrafluoroethylene-glycidyl methacrylate copolymer emulsion.

[0023] The stirring time in step (1) ② is 18-20 min, the washing is deionized water washing for 3-5 times, and the drying is vacuum drying at 55°C for 10 h.

[0024] The mass ratio of halloysite nanotubes, nano lanthanum fluoride and nano zirconium silicate in step (3) ① is 2:1:2.

[0025] The mass sum of halloysite nanotubes, nano lanthanum fluoride and nano zirconium silicate in step (3) ① accounts for 2-3% of the mass of deionized water.

[0026] The 1H,1H,2H,2H-perfluorodecyl triethoxysilane solution in step (3) ② is prepared by uniformly mixing 1H,1H,2H,2H-perfluorodecyl triethoxysilane and anhydrous ethanol according to a volume ratio of 1:2, and the dropping speed of the 1H,1H,2H,2H-perfluorodecyl triethoxysilane solution is 0.7 mL / min.

[0027] The mass of 1H,1H,2H,2H-perfluorodecyl triethoxysilane added in the 1H,1H,2H,2H-perfluorodecyl triethoxysilane solution in step (3) ② accounts for 5.5% of the mass sum of halloysite nanotubes, nano lanthanum fluoride and nano zirconium silicate in step (3) ①.

[0028] The washing in step (3) ② is deionized water washing for 3 times and anhydrous ethanol washing for 1 time, the drying is vacuum drying at 80°C for 12 h, and the sieving is sieving through a 200 mesh sieve.

[0029] In step (3), firstly, -OH is generated on the surface of LaF3 and ZrSiO4 by hydration of weak base, to provide same reaction sites for subsequent covalent grafting, and then fluorosilane is condensed with -OH on the surface of the three fillers to endow the nano-filler with low surface energy and enhance the compatibility with ETFE resin.

[0030] In step (4), the mixing temperature is 60℃, the mixing time is 5min, and the mixing rotation speed is 300r / min.

[0031] In step (4), the ETFE film is composed of the following raw materials in parts by weight: pretreated ETFE resin 88-90 parts, silanized nano-composite filler 4.5-6.5 parts, tetrafluoroethylene-glycidyl methacrylate copolymer 3.5-5.5 parts.

[0032] In step (4), the feeding section temperature of the twin-screw extruder is 256-258℃, the compression section temperature is 272-274℃, the melting section temperature is 278-280℃, the reaction time is 80-85s, and the screw rotation speed is 190r / min.

[0033] In step (4), a vacuum devolatilization port is arranged in the twin-screw extruder, which is located at the end of the melting section, and the vacuum degree is -0.09MPa, which is used for removing residual silane oligomers.

[0034] In step (4), the longitudinal stretching multiple is 3.0-4.0 times, and the longitudinal stretching temperature is 200-205℃.

[0035] In step (4), the transverse stretching multiple is 2.8-3.5 times, and the transverse stretching temperature is 230-235℃.

[0036] In step (4), the heat setting temperature is 175-180℃, the heat setting time is 30-35s, and after natural cooling to 50℃, the ETFE film is wound to prepare the ETFE film.

[0037] In step (5), the post-treatment is to heat the ETFE film prepared in step (4) at 135-140℃ for 3h, and then naturally cool to room temperature, so as to eliminate the residual internal stress during extrusion molding, and finally clean and dry, to prepare the ETFE film for semiconductor packaging. The cleaning and drying includes: ① soaking in ultrapure water for 13-15min, and gently stirring to avoid scratching the film surface, ② ultrasonic cleaning with 0.1% perfluorohexyl ethanol for 5min, the ultrasonic power is 130W, which enhances the impurity stripping without damaging ETFE; ③ rinsing with ultrapure water for 3 times to remove residual cleaning agent; ④ vacuum drying at 70-75℃ for 1h to avoid ring-opening of epoxy groups caused by high temperature.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] (1) In the preparation method of the ETFE film for semiconductor packaging, the tetrafluoroethylene-glycidyl methacrylate copolymer prepared in step (1) is an epoxy group-containing fluoropolymer, which plays the role of a compatibilizer in the subsequent reaction process. The epoxy group of the glycidyl methacrylate side chain can chemically react with the hydroxyl group of the pretreated ETFE resin in step (2) and the hydroxyl group of the silanized nano-composite filler in step (3) to form a chemical bond, thereby providing a chemical bridging site for the interface bonding between the resin and the filler in step (4), and improving the wear resistance and mechanical properties of the ETFE film. In step (2), the ETFE resin is slightly oxidized to generate hydroxyl groups on the surface of the ETFE molecular chain. The hydroxyl groups can bond with the epoxy groups of the tetrafluoroethylene-glycidyl methacrylate copolymer prepared in step (1), so as to anchor the compatibilizer on the ETFE matrix and avoid the migration of the compatibilizer. In step (3), the surface of the filler is first made to generate hydroxyl groups in a weak alkali environment, which bond with the epoxy groups of the tetrafluoroethylene-glycidyl methacrylate copolymer, and then the nano-composite filler is grafted with fluorosilane to endow the nano-composite filler with low surface energy and match the low surface energy structure of ETFE, thereby avoiding the agglomeration of the filler. The modified filler can be uniformly dispersed in the ETFE matrix in step (4) to form a stable reinforcing system through the chemical bonding of “filler-compatibilizer-ETFE”. In step (4), the pretreated ETFE resin is melted under high temperature and high pressure in a twin-screw extruder, and is fully blended with the silanized nano-composite filler and the tetrafluoroethylene-glycidyl methacrylate copolymer to form complete chemical bonding. The longitudinal stretching and the transverse stretching make the molecular chains oriented to improve the mechanical strength of the film, and the heat setting preliminarily releases the internal stress. In step (5), the residual internal stress is eliminated by heat preservation at 135-140 DEG C, thereby improving the dimensional stability of the film, and the impurities (residual silane) are removed through cleaning to improve the cleanliness of the prepared ETFE film.

[0040] (2) The preparation method of the ETFE film for semiconductor packaging, the silanized nano composite filler selects halloysite nanotubes, nano lanthanum fluoride and nano zirconium silicate for compounding, the three substances have a synergistic relationship, the halloysite nanotubes have rigidity and toughness, on the one hand, the halloysite nanotubes can disperse stress concentration, on the other hand, the halloysite nanotubes can prevent crack propagation. The nano lanthanum fluoride has relatively high Mohs hardness and low friction coefficient, can form a wear-resistant layer on the surface of the ETFE film, reduces material loss when rubbing, and the self-lubricating property can reduce the friction resistance between the film and the contacted object, and reduce the wear loss. The nano zirconium silicate has high Mohs hardness and elastic modulus, can improve the surface rigidity of the film, reduce the wear loss and wear scar depth. The hardness of the three fillers is gradient distribution from high to low (ZrSiO4>LaF3>HNTs), when rubbing, ZrSiO4resists main wear, LaF3reduces friction resistance, and the halloysite nanotubes avoid brittle fracture of the film due to too high rigidity.

[0041] (3) The ETFE film for semiconductor packaging prepared by the preparation method has excellent mechanical properties and wear resistance. DETAILED DESCRIPTION

[0042] Example 1

[0043] The preparation method of the ETFE film for semiconductor packaging in the embodiment 1 comprises the following steps:

[0044] (1) Preparation of tetrafluoroethylene-glycidyl methacrylate copolymer

[0045] ① Deionized water, 4,8-dioxa-3H-perfluorononanoic acid ammonium and potassium persulfate are added into a high-pressure reaction kettle, the high-pressure reaction kettle is sealed, the air in the kettle is replaced with nitrogen for 3 times, then tetrafluoroethylene is introduced until the pressure in the kettle is 0.2 MPa, the nitrogen is replaced for 2 times, and the pressure is released to normal pressure after each replacement, then tetrafluoroethylene is continuously introduced until the pressure in the kettle is 2.5 MPa, glycidyl methacrylate is pressed into the high-pressure reaction kettle with nitrogen within 5 min, the temperature is increased to 56 ℃ for stirring reaction, and tetrafluoroethylene is supplemented to maintain the pressure in the kettle at 2.5 MPa during the reaction; when the reaction is performed for 3 h, methanol polymerization inhibitor is added into the high-pressure reaction kettle, the heating is stopped when the reaction is performed for 3.3 h, and the temperature is reduced to room temperature, to prepare a tetrafluoroethylene-glycidyl methacrylate copolymer emulsion;

[0046] ② The coagulant is added into the tetrafluoroethylene-glycidyl methacrylate copolymer emulsion, the copolymer is precipitated by stirring, and the tetrafluoroethylene-glycidyl methacrylate copolymer is prepared after washing and drying;

[0047] (2) Pretreatment of ETFE resin

[0048] The ETFE resin is kept at 150°C for 2.5h in air atmosphere, and naturally cooled to prepare a pretreated ETFE resin;

[0049] (3) Silanization treatment of the nanocomposite filler

[0050] ① The halloysite nanotube, nanometer lanthanum fluoride and nanometer zirconium silicate are dissolved in deionized water, then ammonia water is added to adjust the pH value of the system to 9.0, and ultrasonic treatment is carried out at 34°C for 30min;

[0051] ② The silanization-treated nanocomposite filler is prepared by adding 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane solution dropwise into the above reaction system, refluxing at 82°C for 4h, then filtering, washing, drying and sieving;

[0052] (4) The pretreated ETFE resin, the silanization-treated nanocomposite filler and the tetrafluoroethylene-glycidyl methacrylate copolymer are uniformly mixed, then put into a twin-screw extruder for melt blending to obtain a blend, the blend is extruded into a sheet through a T-shaped die, and finally longitudinally stretched, transversely stretched and heat set to prepare an ETFE film;

[0053] (5) The ETFE film prepared in step (4) is post-treated to prepare an ETFE film for semiconductor packaging.

[0054] In step (1) ①, the mass of 4,8-dioxa-3H-perfluorononanoate ammonium accounts for 0.4% of the mass sum of deionized water, 4,8-dioxa-3H-perfluorononanoate ammonium, potassium persulfate, tetrafluoroethylene and glycidyl methacrylate.

[0055] In step (1) ①, the mass of potassium persulfate accounts for 0.21% of the mass sum of tetrafluoroethylene and glycidyl methacrylate.

[0056] In step (1) ①, the total amount of tetrafluoroethylene introduced is in a molar ratio of 10.5:1 to glycidyl methacrylate.

[0057] In step (1) ①, the mass of deionized water is 3 times the mass sum of tetrafluoroethylene and glycidyl methacrylate.

[0058] In step (1) ①, the mass of the methanol polymerization inhibitor accounts for 0.17% of the mass sum of tetrafluoroethylene and glycidyl methacrylate.

[0059] In step (1) ②, the coagulant is a saturated sodium chloride solution, and the volume of the coagulant added is 5% of the volume of the tetrafluoroethylene-glycidyl methacrylate copolymer emulsion.

[0060] The stirring time in step (1) ② is 19 min, the washing is washing 4 times with deionized water, and the drying is vacuum drying at 55℃ for 10 h.

[0061] The mass ratio of halloysite nanotubes, nano lanthanum fluoride and nano zirconium silicate in step (3) ① is 2:1:2.

[0062] The mass ratio of halloysite nanotubes, nano lanthanum fluoride and nano zirconium silicate in step (3) ① is 2:1:2.

[0063] In step (3) ②, the 1H, 1H, 2H, 2H-perfluorodecyl triethoxysilane solution is prepared by uniformly mixing 1H, 1H, 2H, 2H-perfluorodecyl triethoxysilane and anhydrous ethanol at a volume ratio of 1:2, and the dropping speed of the 1H, 1H, 2H, 2H-perfluorodecyl triethoxysilane solution is 0.7 mL / min.

[0064] In step (3) ②, the mass of 1H, 1H, 2H, 2H-perfluorodecyl triethoxysilane added in the 1H, 1H, 2H, 2H-perfluorodecyl triethoxysilane solution accounts for 5.5% of the total mass of halloysite nanotubes, nano lanthanum fluoride and nano zirconium silicate in step (3) ①.

[0065] In step (3) ②, the washing is washing 3 times with deionized water and then washing 1 time with anhydrous ethanol, the drying is vacuum drying at 80℃ for 12 h, and the sieving is sieving through a 200 mesh sieve.

[0066] In step (3), first, LaF3 and ZrSiO4 surfaces are made to generate -OH through weak base hydration, providing the same reaction site for subsequent covalent grafting, and then the surface energy of the nano filler is given through the condensation of fluorosilane and the -OH on the surface of the three fillers, enhancing the compatibility with ETFE resin.

[0067] In step (4), the mixing temperature is 60℃, the mixing time is 5 min, and the mixing speed is 300 r / min.

[0068] In step (4), the ETFE film is composed of the following raw materials in parts by weight: pretreated ETFE resin 89 parts, silanized nano composite filler 5.5 parts, and tetrafluoroethylene-glycidyl methacrylate copolymer 4.5 parts.

[0069] In step (4), the feeding section temperature of the twin-screw extruder is 257℃, the compression section temperature is 273℃, the melting section temperature is 279℃, the reaction time is 83 s, and the screw rotation speed is 190 r / min.

[0070] The double screw extruder in step (4) is provided with a vacuum devolatilization port, which is located at the end of the melting section and has a vacuum degree of -0.09 MPa, and is used for removing residual silane oligomers.

[0071] In step (4), the longitudinal stretching multiple is 3.5, and the longitudinal stretching temperature is 203°C.

[0072] In step (4), the transverse stretching multiple is 3.1, and the transverse stretching temperature is 233°C.

[0073] In step (4), the heat setting temperature is 177°C, the heat setting time is 33 s, and the ETFE film is prepared by winding after natural cooling to 50°C.

[0074] In step (5), the post-treatment is to heat the ETFE film prepared in step (4) at 137°C for 3 h, then naturally cool to room temperature, so as to eliminate the residual internal stress during extrusion molding, and finally clean and dry, to prepare the ETFE film for semiconductor packaging. The cleaning and drying include: ① soaking in ultrapure water for 14 min, and gently stirring to avoid scratching the film surface, ② ultrasonic cleaning with 0.1% perfluorohexyl ethanol for 5 min, with an ultrasonic power of 130 W, to enhance the impurity stripping without damaging the ETFE; ③ rinsing with ultrapure water for 3 times to remove residual cleaning agents; and ④ vacuum drying at 73°C for 1 h to avoid ring-opening of the epoxy groups caused by high temperature.

[0075] Example 2

[0076] The preparation method of the ETFE film for semiconductor packaging in this example 2 is composed of the following steps:

[0077] (1) Preparation of tetrafluoroethylene-glycidyl methacrylate copolymer

[0078] ① Deionized water, 4,8-dioxa-3H-perfluorononanoic acid ammonium and potassium persulfate were added to a high-pressure reaction kettle, the high-pressure reaction kettle was sealed, the air in the kettle was replaced with nitrogen for 3 times, then tetrafluoroethylene was introduced until the pressure in the kettle reached 0.2 MPa, and the nitrogen was replaced twice after each replacement, then the pressure in the kettle was increased to 2.5 MPa by continuously introducing tetrafluoroethylene, and the glycidyl methacrylate was pressed into the high-pressure reaction kettle within 5 min, and the reaction was carried out by stirring at 55°C. During the reaction, tetrafluoroethylene was added to maintain the pressure in the kettle at 2.5 MPa; when the reaction was carried out for 3 h, methanol was added as a polymerization inhibitor, and the reaction was stopped after 3.2 h, and the temperature was lowered to room temperature, to prepare a tetrafluoroethylene-glycidyl methacrylate copolymer emulsion;

[0079] ② Adding a coagulating agent to the tetrafluoroethylene-glycidyl methacrylate copolymer emulsion, stirring to precipitate the copolymer, and washing and drying to obtain the tetrafluoroethylene-glycidyl methacrylate copolymer;

[0080] (2) Pretreatment of the ETFE resin

[0081] The ETFE resin was kept at 150°C for 2.5 h in an air atmosphere, and then naturally cooled to obtain the pretreated ETFE resin.

[0082] (3) Silanization treatment of the nanocomposite filler

[0083] ① The halloysite nanotube, nanometer lanthanum fluoride and nanometer zirconium silicate were dissolved in deionized water, and then ammonia was added to adjust the pH value of the system to 9.0, and then ultrasonic treatment was carried out at 33°C for 30 min;

[0084] ② The 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane solution was added dropwise to the above reaction system, and then refluxed at 81°C for 4 h, and then filtered, washed, dried and sieved to obtain the silanized nanocomposite filler.

[0085] (4) The pretreated ETFE resin, the silanized nanocomposite filler and the tetrafluoroethylene-glycidyl methacrylate copolymer were uniformly mixed, and then fed into a twin-screw extruder for melt blending to obtain a blend, and then the blend was extruded into a sheet through a T-shaped die, and then longitudinally stretched, transversely stretched and heat set to obtain the ETFE film.

[0086] (5) The ETFE film obtained in step (4) was post-treated to obtain the ETFE film for semiconductor packaging.

[0087] In step (1) ①, the mass of the 4,8-dioxa-3H-perfluorononanoate ammonium accounted for 0.4% of the mass sum of the deionized water, the 4,8-dioxa-3H-perfluorononanoate ammonium, the potassium persulfate, the tetrafluoroethylene and the glycidyl methacrylate.

[0088] In step (1) ①, the mass of the potassium persulfate accounted for 0.2% of the mass sum of the tetrafluoroethylene and the glycidyl methacrylate.

[0089] In step (1) ①, the total amount of the tetrafluoroethylene introduced was 10:1 in molar ratio to the glycidyl methacrylate.

[0090] In step (1) ①, the mass of the deionized water was 3 times the mass sum of the tetrafluoroethylene and the glycidyl methacrylate.

[0091] In step (1) ①, the mass of the methanol polymerization inhibitor accounted for 0.17% of the mass sum of the tetrafluoroethylene and the glycidyl methacrylate.

[0092] The coagulant in step (1) ② is a saturated sodium chloride solution, and the volume of the coagulant added is 5% of the volume of the tetrafluoroethylene-glycidyl methacrylate copolymer emulsion.

[0093] The stirring time in step (1) ② is 19 min, the washing is washing with deionized water for 3 times, and the drying is vacuum drying at 55℃ for 10h.

[0094] The mass ratio of halloysite nanotubes, nano lanthanum fluoride, and nano zirconium silicate in step (3) ① is 2:1:2.

[0095] The mass of halloysite nanotubes, nano lanthanum fluoride, and nano zirconium silicate in step (3) ① accounts for 2% of the mass of deionized water.

[0096] In step (3) ②, the 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane solution is prepared by uniformly mixing 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane and anhydrous ethanol according to a volume ratio of 1:2, and the dropping speed of the 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane solution is 0.7mL / min.

[0097] In step (3) ②, the mass of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane in the 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane solution accounts for 5.5% of the mass of halloysite nanotubes, nano lanthanum fluoride, and nano zirconium silicate in step (3) ①.

[0098] In step (3) ②, the washing is washing with deionized water for 3 times and then washing with anhydrous ethanol for 1 time, the drying is vacuum drying at 80℃ for 12h, and the sieving is sieving through a 200 mesh sieve.

[0099] In step (3), first, LaF3 and ZrSiO4 surfaces are made to generate -OH through weak base hydration, providing the same reaction site for subsequent covalent grafting, and then the surface energy of the nano filler is given through the condensation of fluorosilane with the -OH on the surface of the three fillers, enhancing the compatibility with ETFE resin.

[0100] In step (4), the mixing temperature is 60℃, the mixing time is 5min, and the mixing speed is 300r / min.

[0101] In step (4), the ETFE film is composed of the following raw materials in parts by weight: pretreated ETFE resin 88 parts, nano composite filler 4.5 parts, tetrafluoroethylene-glycidyl methacrylate copolymer 5.5 parts.

[0102] The temperature of the feeding section of the double screw extruder in step (4) is 256°C, the temperature of the compression section is 272°C, the temperature of the melting section is 278°C, the reaction time is 80s, and the screw rotation speed is 190r / min.

[0103] A vacuum devolatilization port is arranged in the double screw extruder in step (4), which is located at the end of the melting section, and the vacuum degree is -0.09MPa, which is used for removing residual silane oligomers.

[0104] The longitudinal stretching multiple in step (4) is 3.0, and the longitudinal stretching temperature is 200°C.

[0105] The transverse stretching multiple in step (4) is 2.8, and the transverse stretching temperature is 230°C.

[0106] The heat setting temperature in step (4) is 175°C, the heat setting time is 30s, and the ETFE film is prepared by winding after natural cooling to 50°C.

[0107] The post-treatment in step (5) is to heat the ETFE film prepared in step (4) at 135°C for 3h, and then naturally cool to room temperature, so as to eliminate the residual internal stress during extrusion molding, and finally clean and dry, to prepare the ETFE film for semiconductor packaging. The cleaning and drying includes: ① soaking in ultrapure water for 13min, gentle stirring to avoid scratching the film surface, ②ultrasonic cleaning with 0.1% perfluorohexyl ethanol for 5min, the ultrasonic power is 130W, which enhances the impurity stripping without damaging ETFE; ③ultrapure water rinsing for 3 times to remove residual cleaning agent; ④70°C vacuum drying for 1h to avoid ring-opening of the epoxy group caused by high temperature.

[0108] Example 3

[0109] The preparation method of the ETFE film for semiconductor packaging in this example 3 is composed of the following steps:

[0110] (1) Preparation of tetrafluoroethylene-glycidyl methacrylate copolymer

[0111] ① Into a high-pressure reactor, deionized water, 4,8-dioxa-3H-perfluorononanoic acid ammonium and potassium persulfate were added. After the high-pressure reactor was sealed, the air in the reactor was replaced with nitrogen for 3 times. Then tetrafluoroethylene was introduced into the reactor until the pressure reached 0.2 MPa. The nitrogen was replaced for 2 times, and the reactor was emptied to normal pressure after each replacement. Then tetrafluoroethylene was continuously introduced into the reactor until the pressure reached 2.5 MPa. Gycidyl methacrylate was introduced into the reactor with nitrogen within 5 min. The reactor was heated to 58 ℃ and stirred. Tetrafluoroethylene was continuously added to maintain the pressure at 2.5 MPa during the reaction. When the reaction was carried out for 3 h, methanol was added into the reactor as a polymerization inhibitor. When the reaction was carried out for 3.4 h, the heating was stopped, and the reactor was cooled to room temperature. Thus, a tetrafluoroethylene-gycidyl methacrylate copolymer emulsion was prepared;

[0112] ② The tetrafluoroethylene-gycidyl methacrylate copolymer emulsion was added with a coagulant, and the copolymer was precipitated by stirring. After washing and drying, a tetrafluoroethylene-gycidyl methacrylate copolymer was prepared.

[0113] (2) Pretreatment of ETFE resin

[0114] The ETFE resin was heated at 150 ℃ in air for 2.5 h, and then naturally cooled to prepare a pretreated ETFE resin.

[0115] (3) Silanization treatment of nanocomposite filler

[0116] ① The halloysite nanotube, nanometer lanthanum fluoride and nanometer zirconium silicate were dissolved in deionized water, and then ammonia water was added to adjust the pH value of the system to 9.0. The system was ultrasonically treated at 35 ℃ for 30 min.

[0117] ② The 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane solution was added dropwise into the above reaction system, and the system was refluxed at 83 ℃ for 4 h. Then the system was filtered, washed, dried and sieved to prepare a silanized nanocomposite filler.

[0118] (4) The pretreated ETFE resin, the silanized nanocomposite filler and the tetrafluoroethylene-gycidyl methacrylate copolymer were uniformly mixed, and then introduced into a twin-screw extruder for melt blending to obtain a blend. The blend was extruded into a sheet through a T-shaped die. Finally, the ETFE film was prepared by longitudinal stretching, transverse stretching and heat setting.

[0119] (5) The ETFE film prepared in step (4) was post-treated to prepare an ETFE film for semiconductor packaging.

[0120] The mass of 4,8-dioxa-3H-perfluorononanoic acid ammonium in step (1) ① accounts for 0.4% of the mass sum of deionized water, 4,8-dioxa-3H-perfluorononanoic acid ammonium, potassium persulfate, tetrafluoroethylene and glycidyl methacrylate.

[0121] The mass of potassium persulfate in step (1) ① accounts for 0.23% of the mass sum of tetrafluoroethylene and glycidyl methacrylate.

[0122] The molar ratio of the total amount of tetrafluoroethylene to glycidyl methacrylate in step (1) ① is 11:1.

[0123] The mass of deionized water in step (1) ① is 3 times the mass sum of tetrafluoroethylene and glycidyl methacrylate.

[0124] The mass of the methanol polymerization inhibitor in step (1) ① accounts for 0.17% of the mass sum of tetrafluoroethylene and glycidyl methacrylate.

[0125] The coagulant in step (1) ② is a saturated sodium chloride solution, and the volume of the coagulant added is 5% of the volume of the tetrafluoroethylene-glycidyl methacrylate copolymer emulsion.

[0126] The stirring time in step (1) ② is 20 min, the washing is deionized water washing 5 times, and the drying is vacuum drying at 55°C for 10h.

[0127] The mass ratio of halloysite nanotubes, nano lanthanum fluoride and nano zirconium silicate in step (3) ① is 2:1:2.

[0128] The mass sum of halloysite nanotubes, nano lanthanum fluoride and nano zirconium silicate in step (3) ① accounts for 3% of the mass of deionized water.

[0129] The 1H,1H,2H,2H-perfluorodecyl triethoxysilane solution in step (3) ② is prepared by uniformly mixing 1H,1H,2H,2H-perfluorodecyl triethoxysilane and anhydrous ethanol according to a volume ratio of 1:2, and the dropwise adding speed of the 1H,1H,2H,2H-perfluorodecyl triethoxysilane solution is 0.7mL / min.

[0130] The mass of 1H,1H,2H,2H-perfluorodecyl triethoxysilane added in the 1H,1H,2H,2H-perfluorodecyl triethoxysilane solution in step (3) ② accounts for 5.5% of the mass sum of halloysite nanotubes, nano lanthanum fluoride and nano zirconium silicate in step (3) ①.

[0131] The washing in step (3) ② is deionized water washing 3 times and anhydrous ethanol washing 1 time, the drying is vacuum drying at 80°C for 12h, and the sieving is sieving through a 200 mesh sieve.

[0132] In step (3), firstly, -OH is generated on the surface of LaF3 and ZrSiO4 by hydration of weak base, to provide same reaction sites for subsequent covalent grafting, then fluorosilane is condensed with -OH on the surface of the three fillers to endow the nano-filler with low surface energy and enhance the compatibility with ETFE resin.

[0133] In step (4), the mixing temperature is 60℃, the mixing time is 5 min, and the mixing speed is 300 r / min.

[0134] In step (4), the ETFE film is composed of the following raw materials in parts by weight: pretreated ETFE resin 90 parts, silanized nano-composite filler 6.5 parts, and tetrafluoroethylene-glycidyl methacrylate copolymer 5.5 parts.

[0135] In step (4), the feeding section temperature of the twin-screw extruder is 258℃, the compression section temperature is 274℃, the melting section temperature is 280℃, the reaction time is 85 s, and the screw speed is 190 r / min.

[0136] In step (4), a vacuum devolatilization port is arranged in the twin-screw extruder, which is located at the end of the melting section, and the vacuum degree is -0.09 MPa, which is used for removing residual silane oligomers.

[0137] In step (4), the longitudinal stretching multiple is 4.0 times, and the longitudinal stretching temperature is 205℃.

[0138] In step (4), the transverse stretching multiple is 3.5 times, and the transverse stretching temperature is 235℃.

[0139] In step (4), the heat setting temperature is 180℃, the heat setting time is 35 s, and the ETFE film is prepared by winding after natural cooling to 50℃.

[0140] In step (5), the post-treatment is to heat the ETFE film prepared in step (4) at 140℃ for 3 h, then naturally cool to room temperature, so as to eliminate the residual internal stress during extrusion molding, and finally clean and dry, to prepare the ETFE film for semiconductor packaging. The cleaning and drying includes: ① soaking in ultrapure water for 15 min, gentle stirring to avoid scratching the film surface, ② ultrasonic cleaning with 0.1% perfluorohexyl ethanol for 5 min, ultrasonic power is 130 W, to enhance the impurity stripping without damaging ETFE; ③ ultrapure water rinsing for 3 times to remove residual cleaning agent; ④ vacuum drying at 75℃ for 1 h to avoid ring-opening of epoxy groups caused by high temperature.

[0141] Comparative Example 1

[0142] The preparation method of the ETFE film for semiconductor packaging according to the comparative example 1 is the same as that of the example 1, and the only difference is that no halloysite nanotube is added in step (3), and the mass ratio of the nanometer lanthanum fluoride to the nanometer zirconium silicate in step (3) ① is 1:2.

[0143] Comparative example 2

[0144] The preparation method of the ETFE film for semiconductor packaging according to the comparative example 2 is the same as that of the example 1, and the only difference is that no nanometer lanthanum fluoride is added in step (3), and the mass ratio of the halloysite nanotube to the nanometer zirconium silicate in step (3) ① is 1:1.

[0145] Comparative example 3

[0146] The preparation method of the ETFE film for semiconductor packaging according to the comparative example 3 is the same as that of the example 1, and the only difference is that no nanometer zirconium silicate is added in step (3), and the mass ratio of the halloysite nanotube to the nanometer lanthanum fluoride in step (3) ① is 2:1.

[0147] The ETFE films for semiconductor packaging prepared in the examples 1-3 and the comparative examples 1-3 are subjected to performance testing, the ETFE film prepared according to the application is cut to prepare a standard rectangular tensile sample with a size of 20 mm x 5 mm, the sample is prepared by punching to ensure that there is no visible defect. Then the sample is fixed on a clamp, and then the sample is stretched at a speed of 10 mm / min according to the ISO 527 standard, the wear resistance is detected according to the national standard GB / T 5478-2008 “Plastic Rolling Wear Test Method”, the sample is cut into a square with a side length of 100 mm, and a hole with a diameter of 6.5 mm is opened in the center, the sample is weighed before and after the test, and the precision is 1 mg, (the sample mass before the test-the sample mass after the test) / the sample mass before the test x 100%=the wear rate (%); three samples are prepared for each sample for determination, and the test data is taken as an average value; the test results are shown in the following table 1.

[0148] Table 1 Performance test results of ETFE film for semiconductor packaging

[0149]

[0150] It can be known from table 1 that the breaking tensile strength of the ETFE film for semiconductor packaging prepared according to the application is much greater than that of the comparative examples 1-3, and the wear rate is much smaller than that of the comparative examples 1-3. In the comparative examples 1-3, the performance of the prepared ETFE film is reduced due to the absence of any one of halloysite nanotube, nanometer lanthanum fluoride or nanometer zirconium silicate in the nanometer composite filler.

[0151] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, as long as the changes or modifications do not deviate from the technical solution of the present application. Any modification, change, equivalent change and modification of the above embodiments made according to the technical essence of the present application still belong to the scope of the technical solution of the present application.

Claims

1. A method for preparing an ETFE thin film for semiconductor packaging, characterized in that: It consists of the following steps: (1) Preparation of tetrafluoroethylene-glycidyl methacrylate copolymer ① Add deionized water, ammonium 4,8-dioxa-3H-perfluorononanoate, and potassium persulfate to a high-pressure reactor. After sealing the reactor, replace the air inside with nitrogen three times. Then, introduce tetrafluoroethylene until the pressure inside the reactor reaches 0.2 MPa, replace the nitrogen twice, and vent to atmospheric pressure after each replacement. Then, continue to introduce tetrafluoroethylene to raise the pressure inside the reactor to 2.5 MPa. Within 5 minutes, use nitrogen to force glycidyl methacrylate into the high-pressure reactor. Heat to 55-58℃ and stir the reaction. During the reaction, maintain the pressure inside the reactor at 2.5 MPa by adding tetrafluoroethylene. When the reaction has proceeded for 3 hours, add methanol polymerization inhibitor to the high-pressure reactor. Stop heating when the reaction has proceeded for 3.2-3.4 hours and cool to room temperature to prepare a tetrafluoroethylene-glycidyl methacrylate copolymer emulsion. ② Add a coagulant to the tetrafluoroethylene-glycidyl methacrylate copolymer emulsion, stir to precipitate the copolymer, and then wash and dry to prepare the tetrafluoroethylene-glycidyl methacrylate copolymer. (2) Pretreatment of ETFE resin Pretreated ETFE resin was prepared by keeping ETFE resin at 150℃ in air for 2.5 hours and then cooling it naturally. (3) Silanization treatment of nanocomposite fillers ① Dissolve halloysite nanotubes, nano-lanthanum fluoride and nano-zirconium silicate in deionized water, then add ammonia to adjust the pH of the system to 9.0, and sonicate at 33-35℃ for 30 min; ② Add 1H,1H,2H,2H-perfluorodecyltriethoxysilane solution dropwise to the above reaction system, reflux at 81-83℃ for 4h, then filter, wash, dry and sieve to prepare silanized nanocomposite filler. (4) The pretreated ETFE resin, the silanized nanocomposite filler and the tetrafluoroethylene-glycidyl methacrylate copolymer are mixed evenly and then fed into a twin-screw extruder for melt blending to obtain a blend. The blend is extruded into sheets through a T-die and finally subjected to longitudinal stretching, transverse stretching and heat setting to prepare an ETFE film. (5) The ETFE film prepared in step (4) is post-processed to prepare an ETFE film for semiconductor packaging; Wherein: the ETFE film described in step (4) is composed of the following raw materials in parts by weight: 88-90 parts of pretreated ETFE resin, 4.5-6.5 parts of silanized nanocomposite filler, and 3.5-5.5 parts of tetrafluoroethylene-glycidyl methacrylate copolymer.

2. The method for preparing an ETFE thin film for semiconductor packaging according to claim 1, characterized in that: In step (1)①, the mass of ammonium 4,8-dioxa-3H-perfluorononanoate accounts for 0.4% of the total mass of deionized water, ammonium 4,8-dioxa-3H-perfluorononanoate, potassium persulfate, tetrafluoroethylene, and glycidyl methacrylate. In step (1)①, the mass of potassium persulfate accounts for 0.2-0.23% of the combined mass of tetrafluoroethylene and glycidyl methacrylate; In step (1)①, the total amount of tetrafluoroethylene introduced is in a molar ratio of 10-11:1 to glycidyl methacrylate. In step (1)①, the mass of deionized water is 3 times the combined mass of tetrafluoroethylene and glycidyl methacrylate; In step (1)①, the mass of the methanol polymerization inhibitor accounts for 0.17% of the total mass of tetrafluoroethylene and glycidyl methacrylate.

3. The method for preparing an ETFE thin film for semiconductor packaging according to claim 1, characterized in that: The coagulant mentioned in step (1) ② is a saturated sodium chloride solution, and the volume of the coagulant added is 5% of the volume of the tetrafluoroethylene-glycidyl methacrylate copolymer emulsion; In step (1) ②, the stirring time is 18-20 min, the washing is done by washing with deionized water 3-5 times, and the drying is done by vacuum drying at 55℃ for 10 h.

4. The method for preparing an ETFE thin film for semiconductor packaging according to claim 1, characterized in that: In step (3)①, the mass ratio of halloysite nanotubes, nano-lanthanum fluoride, and nano-zirconium silicate is 2:1:2; In step (3)①, the mass of halloysite nanotubes, nano-lanthanum fluoride, and nano-zirconium silicate accounts for 2-3% of the mass of deionized water.

5. The method for preparing an ETFE thin film for semiconductor packaging according to claim 1, characterized in that: In step (3) ②, the 1H,1H,2H,2H-perfluorodecyltriethoxysilane solution was prepared by mixing 1H,1H,2H,2H-perfluorodecyltriethoxysilane with anhydrous ethanol at a volume ratio of 1:

2. The dropping rate of the 1H,1H,2H,2H-perfluorodecyltriethoxysilane solution was 0.7 mL / min. In step (3) ②, the mass of 1H,1H,2H,2H-perfluorodecyltriethoxysilane added to the 1H,1H,2H,2H-perfluorodecyltriethoxysilane solution accounts for 5.5% of the mass of halloysite nanotubes, nano-lanthanum fluoride, and nano-zirconium silicate in step (3) ①. In step (3) ②, the washing is performed by washing with deionized water 3 times and then washing with anhydrous ethanol once. The drying is performed by vacuum drying at 80°C for 12 hours. The sieving is performed by passing through a 200-mesh sieve.

6. The method for preparing an ETFE thin film for semiconductor packaging according to claim 1, characterized in that: In step (4), the mixing temperature is 60℃, the mixing time is 5min, and the mixing speed is 300r / min.

7. The method for preparing an ETFE thin film for semiconductor packaging according to claim 1, characterized in that: In step (4), the temperature of the feeding section of the twin-screw extruder is 256-258℃, the temperature of the compression section is 272-274℃, the temperature of the melting section is 278-280℃, the reaction time is 80-85s, and the screw speed is 190r / min.

8. The method for preparing an ETFE thin film for semiconductor packaging according to claim 1, characterized in that: In step (4), the longitudinal stretching ratio is 3.0-4.0 times, and the longitudinal stretching temperature is 200-205℃; In step (4), the transverse stretching ratio is 2.8-3.5 times, and the transverse stretching temperature is 230-235℃.

9. The method for preparing an ETFE thin film for semiconductor packaging according to claim 1, characterized in that: The heat setting temperature in step (4) is 175-180℃, the heat setting time is 30-35s, and after natural cooling to 50℃, the film is wound up to obtain ETFE film.

10. The method for preparing an ETFE thin film for semiconductor packaging according to claim 1, characterized in that: The post-processing described in step (5) involves keeping the ETFE film prepared in step (4) at 135-140℃ for 3 hours, then naturally cooling it to room temperature, and finally cleaning and drying it to obtain the ETFE film for semiconductor packaging.

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