Ethylene tetrafluoroethylene copolymer film, method for its production and use as a separating film for the manufacture of a semiconductor device

Abstract

A film which is an ethylene tetrafluoroethylene copolymer film, characterized in that the crystallinity, which is determined by the following formula (1) from the peak area S 20 in the vicinity of 2θ = 20°, the peak area S 19 in the vicinity of 2θ = 19° and the peak area S 17 in the vicinity of 2θ = 17° in the diffraction intensity curve obtainable by an X-ray diffraction method, is from 55 to 70%, and the fraction of the quasicrystalline layer obtainable by the following formula (2) is from 10 to 20%, Crystallinity (%) = (S 19 + S 20) / (S 17 + S 19 + S 20) × 100 Percentage of quasicrystalline layer (%) = S 20 / ( S 17 + S 19 + S 20 ) × 100

Description

TECHNICAL AREA

[0001] The present invention relates to an ethylene tetrafluoroethylene copolymer (hereinafter referred to as “ETFE”) film, a method for its production and its use as a separating film for the manufacture of a semiconductor device. STATE OF THE ART

[0002] A semiconductor chip is typically enclosed (encapsulated) in a container called a package to block and protect it from the outside air, and mounted as a semiconductor device on a substrate. A curable resin, such as epoxy resin, is used for the package.

[0003] A known method for manufacturing a semiconductor device is a transfer pressing process or a compression molding process, in which a semiconductor chip or the like is arranged so that it is positioned at a predetermined location in a mold tool and a curable resin is filled into the mold tool and cured.

[0004] In the aforementioned transfer pressing or compression molding process, a release film can be arranged on the surface of the mold to facilitate the separation of the housing from the mold tool, so that it is in contact with the curable resin.

[0005] For good separation properties and good mold continuity, a fluororesin film, in particular an ETFE film, is usually used as a release film.

[0006] In recent years, there has been an increasing number of high-capacity NAND flash memory devices. In this type of memory, multiple memory chips are stacked in several layers, resulting in a significant overall thickness. Consequently, the cavity of the mold used to manufacture the device also becomes quite deep.

[0007] When a release film is used in a compression molding process, the mold release film, which is positioned on the surface of the mold, is stretched and then retracted during the molding process. This can easily lead to the formation of creases in the release film. The problem of wrinkling becomes more pronounced as the mold cavity deepens, and in some cases, the creased release film can become embedded in the curing resin and is difficult to separate.

[0008] To address this problem, patent document 1 proposes a compression molding device equipped with a compression molding tool with a specific structure to eliminate the wrinkles formed in the film.

[0009] Patent document 2 proposes a separating film for use in the manufacture of semiconductor devices, the tensile modulus of which is 10 to 24 MPa at 132 °C and the maximum peel strength of which is at most 0.8 N / 25 mm.

[0010] On the other hand, a melt forming process is usually used as a method for producing a fluororesin film, in which a molten fluororesin is extruded from a nozzle and then cooled and allowed to solidify.

[0011] Patent document 3 proposes a method for producing a fluororesin film in which, at the time of obtaining a flat film by contacting a molten fluororesin extruded from a T-nozzle with a cooling roller to cool and solidify it, the surface temperature of the cooling roller is set to 80 to 140 °C and hot air at 50 to 160 °C is blown onto the film on this cooling roller. It is stated that, according to this method, it is possible to produce a fluororesin film with excellent optical properties and excellent flatness without compromising the outstanding properties of the fluororesin.

[0012] Patent document 4 proposes a method for producing a film comprising a melting step of heating a copolymer containing ethylene units, tetrafluoroethylene units, and specific (fluoroalkyl)ethylene units; a forming step of shaping the molten copolymer into a film; a cooling step of quenching the resulting film by contacting it with a cooling roller at a temperature not more than 10 °C higher than the glass transition temperature of the film, while maintaining the crystallization temperature of the copolymer; and a recovery step of obtaining the quenched film. It is stated that, according to this method, it is possible to produce a film whose crystallinity, as determined by X-ray diffraction measurement, is at most 68%, and that the film exhibits excellent transparency and heat resistance.

[0013] According to patent documents 3 and 4, no investigation was carried out regarding the use of the available fluororesin film as a release film in the aforementioned compression molding process.

[0014] Patent document 5 discloses a tetrafluoroethylene / ethylene copolymer composition and patent document 6 describes a low-melting tetrafluoroethylene copolymer. DOCUMENTS ON THE STATE OF TECHNICAL PATENT DOCUMENTS Patent document 1: JP 2013 - 180 461 A Patent document 2: WO 2013 / 115187 A1 Patent document 3: JP S61 - 27 231 A Patent document 4: JP 2014 - 141 646 A and US 2015 / 0 252 156 A1 Patent document 5: US 2004 / 0 116 606 A1 Patent document 6: US 6,197,904 B1 REVELATION OF THE INVENTIONAL PROBLEM

[0015] With the compression molding device described in patent document 1, the device structure tends to be unnecessarily long, and, as the present inventors have found, the effect for eliminating wrinkles was insufficient.

[0016] The separating film described in patent document 2 did not provide sufficient protection against the formation of wrinkles during compression molding, as has been found by the present inventors.

[0017] The present inventors used a fluorinated resin film obtainable by any of the methods described in patent documents 3 and 4 as a release film in the aforementioned compression molding process, but the effect was insufficient to prevent the formation of wrinkles during compression molding.

[0018] One object of the present invention is to provide an ETFE film which is less likely to form wrinkles when stretched and retracted, and a method for producing it. SOLUTION TO THE PROBLEM

[0019] The present invention provides an ETFE film, a method for its production and a use thereof as a separating film for the production of a semiconductor device with the structure according to the following [1] to

[10] .

[0020] [1] Film which is an ethylene tetrafluoroethylene copolymer film, characterized in that the crystallinity, which is determined by the following formula (1) from the peak area S 20 in the vicinity of 2θ = 20°, the peak area S 19 in the vicinity of 2θ = 19° and the peak area S 17in the vicinity of 2θ = 17° in the diffraction intensity curve obtainable by an X-ray diffraction method, is from 55 to 70%, and the fraction of the quasicrystalline layer obtainable by the following formula (2) is from 10 to 20%, Crystallinity(%)=(S19+S20) / (S17+S19+S20)×100 Percentage of quasicrystalline layer (%) = S20 / (S17+S19+S20)×100

[0021] [2] Film, characterized in that it is produced from a mixture of the following ETFE (A) and the following ETFE (B) in a mass ratio of 80 / 20 to 95 / 5, ETFE (A): an ethylene-tetrafluoroethylene copolymer with tetrafluoroethylene units, ethylene units and third units based on a monomer other than tetrafluoroethylene and ethylene, wherein the molar ratio of the tetrafluoroethylene units to the ethylene units is from 45 / 55 to 65 / 35 and the proportion of the third units to the total of the tetrafluoroethylene units and the ethylene units is from 0.5 to 1.5 mol%, wherein the monomer other than tetrafluoroethylene and ethylene is a fluoroalkylethylene known by the formula X(CF2) n CY=CH2 is represented, where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer from 2 to 8.

[0022] ETFE (B): an ethylene-tetrafluoroethylene copolymer comprising tetrafluoroethylene units, ethylene units and third units based on a monomer other than tetrafluoroethylene and ethylene, wherein the molar ratio of the tetrafluoroethylene units to the ethylene units is from 45 / 55 to 65 / 35 and the proportion of the third units to the total of the tetrafluoroethylene units and the ethylene units is from 3.5 to 6 mol%, wherein the monomer other than tetrafluoroethylene and ethylene is a fluoroalkylethylene defined by the formula X(CF2) n CY=CH2 is represented, where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer from 2 to 8.

[0023] [3] Slide according to [2], where the crystallinity is determined by the following formula (1) from the peak area S 20 in the vicinity of 2θ = 20°, the peak area S 19 in the vicinity of 2θ = 19° and the peak area S 17in the vicinity of 2θ = 17° in the diffraction intensity curve obtainable by an X-ray diffraction method, is from 55 to 70%, and the fraction of the quasicrystalline layer obtainable by the following formula (2) is from 10 to 20%, Crystallinity(%)=(S19+S20) / (S17+S19+S20)×100 Percentage of quasicrystalline layer (%) = S20 / (S17+S19+S20)×100

[0024] [4] Method for producing the film according to [1], characterized by extruding a melt of an ethylene tetrafluoroethylene copolymer from an extrusion die in the form of a film, contacting the film with a first cooling device so that the surface temperature is higher than the crystallization temperature of the copolymer and lower than the melting point of the copolymer for a predetermined time, so that a primarily cooled product is obtained, then removing the primarily cooled product from the first cooling device and cooling it within a predetermined time from the time of removal by a second cooling device to a temperature of at least (melting point of the copolymer - 120 °C) and at most (melting point of the copolymer - 80 °C).

[0025] [5] Method for producing a film according to [4], wherein the period of contact of the film with the first cooling device is from 3 to 20 seconds.

[0026] [6] Method for producing a film according to [4] or [5], wherein the time for cooling to the aforementioned temperature by the second cooling device from the time of detachment from the first cooling device is within one second.

[0027] [7] Method for producing a film according to [4] to [6], wherein the ethylene-tetrafluoroethylene copolymer is a copolymer with tetrafluoroethylene units, ethylene units and third units based on a monomer different from tetrafluoroethylene and ethylene.

[0028] [8] Method for producing a film according to one of [4] to [7], wherein the cooling of the primarily cooled product is carried out by contact with a cooling roller, an air scraper or immersion in water.

[0029] [9] Process for producing the ethylene tetrafluoroethylene copolymer film according to [1] to [3], characterized by extruding a molten mixture of the following ETFE (A) and the following ETFE (B) in a mass ratio of 80 / 20 to 95 / 5 from an extrusion die in the form of a film, followed by cooling,

[0030] ETFE (A): an ethylene-tetrafluoroethylene copolymer comprising tetrafluoroethylene units, ethylene units and third units based on a monomer other than tetrafluoroethylene and ethylene, wherein the molar ratio of the tetrafluoroethylene units to the ethylene units is from 45 / 55 to 65 / 35 and the proportion of the third units to the total of the tetrafluoroethylene units and the ethylene units is from 0.5 to 1.5 mol%, wherein the monomer other than tetrafluoroethylene and ethylene is a fluoroalkylethylene defined by the formula X(CF2) n CY=CH2 is represented, where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer from 2 to 8.

[0031] ETFE (B): an ethylene-tetrafluoroethylene copolymer comprising tetrafluoroethylene units, ethylene units and third units based on a monomer other than tetrafluoroethylene and ethylene, wherein the molar ratio of the tetrafluoroethylene units to the ethylene units is from 45 / 55 to 65 / 35 and the proportion of the third units to the total of the tetrafluoroethylene units and the ethylene units is from 3.5 to 6 mol%, wherein the monomer other than tetrafluoroethylene and ethylene is a fluoroalkylethylene defined by the formula X(CF2) n CY=CH2 is represented, where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer from 2 to 8.

[0032]

[10] Use of the film according to [1] to [3] as a separating film for the manufacture of a semiconductor device. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0033] The ETFE film of the present invention is less likely to form wrinkles when stretched and retracted.

[0034] According to the method for producing an ETFE film of the present invention, an ETFE film can be produced in which the formation of wrinkles is less likely when it is stretched and retracted. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic diagram illustrating a first embodiment of the manufacturing process (i) of the present invention. Fig. Figure 2 is a schematic diagram illustrating a second embodiment of the manufacturing process (i). Fig. Figure 3 is a schematic diagram showing a third embodiment of the manufacturing process (i). Fig.Figure 4 is a cross-sectional view showing steps (1) and (2) in an embodiment of the method for manufacturing a semiconductor device. Fig. Figure 5 is a cross-sectional view showing step (3) in an embodiment of the method for manufacturing a semiconductor device. Fig. Figure 6 is a cross-sectional view showing step (3) in an embodiment of the method for manufacturing a semiconductor device. DESCRIPTION OF EXECUTION FORMS

[0035] The meanings of terms in this description are as follows.

[0036] A "unit" is a general term for a group of atoms formed directly by the polymerization of a monomer and derived from a molecule of that monomer, and for a group of atoms obtainable by chemically transforming a portion of such a group of atoms. Furthermore, units based on a specific monomer can be represented by appending "units" to the monomer name. It should be noted that below, tetrafluoroethylene may be referred to as "TFE," tetrafluoroethylene units may also be referred to as "TFE units," and ethylene units may also be referred to as "E units."

[0037] “ETFE” (ethylene tetrafluoroethylene copolymer) is a copolymer that includes TFE units and E units.

[0038] An "ETFE film" is a molded product obtained by forming ETFE into a film or layered form (collectively referred to as "film form, etc."). The ETFE film may contain additives.

[0039] “Extensibility” encompasses both a lower probability of tearing during stretching under load and a low residual displacement after the load is removed.

[0040] The "arithmetic mean roughness Ra" is a value measured according to JIS B0601: 2013 (ISO 4287: 1997, Amd.1: 2009). The standard length Ir (limit value λc) for the roughness curve is 0.8 mm.

[0041] The "flowability" of ETFE is a value measured at a stress of 49 N at 297 °C according to ASTM D3159. Flowability is also referred to as "MFR" (molecular weight). MFR is an index of molecular weight; the higher the MFR, the lower the molecular weight.

[0042] The ETFE film in the present invention is an ETFE film whose crystallinity is determined by the following formula (1) from the peak area S 20 in the vicinity of 2θ = 20°, the peak area S 19 in the vicinity of 2θ = 19° and the peak area S 17 in the vicinity of 2θ = 17° in the diffraction intensity curve, which is obtainable by measurement by an X-ray diffraction method, is of 55 to 70%, and the fraction of the quasicrystalline layer, which can be obtained by the following formula (2), is of 10 to 20% (hereinafter an ETFE foil with such specific crystallinity and such fraction of the quasicrystalline layer is also referred to as ‘ETFE foil (I)’). Crystallinity(%)=(S19+S20) / (S17+S19+S20)×100 Percentage of quasicrystalline layer (%) = S20 / (S17+S19+S20)×100

[0043] The following two means are preferred for obtaining the ETFE foil (I), and such two means may be used in a combination. However, means for obtaining the ETFE foil (I) are not limited to these. Furthermore, the following two means are not limited as means for obtaining the ETFE foil (I).

[0044] The first method is a process in which ETFE forming the ETFE foil is composed of the following ETFE (A) and ETFE (B), wherein the mass ratio of ETFE (A) to ETFE (B) is from 80 / 20 to 95 / 5.

[0045] ETFE (A): a copolymer with TFE units and E units and third units based on a monomer other than TFE and ethylene, wherein the molar ratio of TFE units to E units is from 45 / 55 to 65 / 35 and the proportion of the third units to the total of TFE units and E units is from 0.5 to 1.5 mol%, wherein the monomer other than tetrafluoroethylene and ethylene is a fluoroalkylethylene described by the formula X(CF2) n CY=CH2 is represented, where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer from 2 to 8.

[0046] ETFE (B): a copolymer with TFE units and E units and third units based on a monomer other than TFE and ethylene, wherein the molar ratio of TFE units to E units is from 45 / 55 to 65 / 35 and the proportion of the third units to the total of TFE units and E units is from 3.5 to 6 mol%, wherein the monomer other than tetrafluoroethylene and ethylene is a fluoroalkylethylene described by the formula X(CF2) n CY=CH2 is represented, where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer from 2 to 8.

[0047] Furthermore, the second means is a process for producing a film, characterized by extruding molten ETFE from an extrusion die in the form of a film, contacting the film with a first cooling device so that the surface temperature is higher than the crystallization temperature of the ETFE (hereinafter the crystallization temperature of ETFE may also be referred to as "Tc") and lower than the melting point of the ETFE (hereinafter the melting point of ETFE may also be referred to as "Tm") for a predetermined time, so that a primarily cooled product is obtained, then removing the primarily cooled product from the first cooling device and cooling it within a predetermined time from the time of removal by a second cooling device to a temperature of at least (Tm - 120 °C) and at most (Tm - 80 °C).

[0048] The Tc of ETFE is obtained from the thermal radiation peak when ETFE is heated to 350 °C at 10 °C / min in an air atmosphere and cooled to 200 °C at 10 °C / min using a scanning differential thermal analyzer (manufactured by SII NanoTechnology, Inc., DSC220CU).

[0049] The Tm of ETFE is obtained from the endothermic peak when ETFE is heated to 350 °C at 10 °C / min in an air atmosphere and cooled to 200 °C at 10 °C / min using a scanning differential thermal analyzer (manufactured by SII NanoTechnology, Inc., DSC220CU).

[0050] These are described below. [ETFE film (I)]

[0051] In the diffraction intensity curve, the peak in the vicinity of 2θ = 20° is a peak originating from the quasicrystalline layer of ETFE, the peak in the vicinity of 2θ = 19° is a peak originating from the fully crystalline layer of ETFE, and the peak in the vicinity of 2θ = 17° is a peak originating from the amorphous layer of ETFE.

[0052] Therefore, the crystallinity (%) obtainable by the above formula (1) represents the ratio of the total quasicrystalline and fully crystalline layers to the total quasicrystalline, fully crystalline, and amorphous layers of ETFE in the ETFE foil. The fraction of the quasicrystalline layer obtainable by the above formula (2) represents the fraction of the quasicrystalline layer to the total quasicrystalline, fully crystalline, and amorphous layers.

[0053] The crystallinity specified above is between 55% and 70%, preferably between 60% and 70%. If the crystallinity is within this range, the ETFE film is less likely to tear when stretched. If the crystallinity is less than 55%, the strength of the ETFE film will be low, making it prone to tearing. If the crystallinity exceeds 70%, the ETFE film will be brittle and likely to tear easily.

[0054] The proportion of the quasicrystalline layer is from 10 to 20%, preferably from 10 to 17%. If the proportion of the quasicrystalline layer is at least 10%, the ETFE film will exhibit excellent stretchability, resulting in minimal residual displacement after stretching. Therefore, for example, in the case of manufacturing a semiconductor device using a compression molding process with the ETFE film as a release liner, creases that make mold separation difficult after sealing with the curable resin are less likely to occur. If the proportion of the quasicrystalline layer is at most 20%, the ETFE film will exhibit excellent dimensional stability.

[0055] The measurement of the ETFE film by the X-ray diffraction method is carried out under the following conditions using a powder X-ray diffraction device by attaching a sample, which has been produced by cutting a part of the ETFE film, to a quartz plate for the sample and fixing the same to a sample holder. (Measurement conditions) Measuring device: manufactured by Bruker Co., D2 PHASER Measurement method: 2θ / θ method Measuring range: 2θ = 10 to 30° X-ray intensity: 30 kV, 10 mA X-ray source: CuKα radiation Analysis software: manufactured by Bruker Co., TOPAS Ver. 4.2 Measurement temperature: Room temperature (20 to 25 °C)

[0056] The obtained diffraction intensity curve is fitted using analysis software. A Pearson vii function is used to ensure that the difference between the fitted curve and the actual curve is no more than 10%. A peak separation technique is used to adjust the peak position of the amorphous section to 2θ = 17.268°, and the curve is automatically optimized for the two crystal peaks by setting 20° and 19° as starting points. The peak's full width at half maximum (FWHM) is also automatically optimized. Two crystal peaks are present, and their area ratios are determined. Based on these area ratios, the crystallinity and the proportion of the quasicrystalline layer are calculated using the formulas provided above.

[0057] In the diffraction intensity curve, the peak in the vicinity of 2θ = 20° is usually found in the range of 2θ = 20° ± 0.4, the peak in the vicinity of 2θ = 19° is usually found in the range of 2θ = 19° ± 0.4, and the peak in the vicinity of 2θ = 17° is usually found in the range of 2θ = 17° ± 0.4.

[0058] ETFE, which forms the ETFE film (I), is preferably a polymer comprising TFE units, E units, and third units based on a monomer other than TFE and ethylene (hereinafter also referred to as the "third monomer"). The crystallinity of ETFE can be adjusted by the type and content of the third units. For example, if the third units are based on a monomer containing fluorine atoms, the crystallinity is reduced, and the tensile strength and elongation at high temperature (particularly at about 180 °C) are improved.

[0059] The third monomer can be a monomer with fluorine atoms or a monomer without fluorine atoms.

[0060] The monomer with fluorine atoms can be a fluoroolefin with 2 or 3 carbon atoms, a fluoroalkylethylene, which is given by the formula X(CF2) n CY=CH2 is represented (where X and Y are each independently a hydrogen atom or a fluorine atom and n is an integer from 2 to 8), a fluorinated vinyl ether, a fluorinated monomer with an alicyclic structure, etc.

[0061] Specific examples of the aforementioned fluoroolefin include fluoroethylene (trifluoroethylene, vinylidene fluoride, vinyl fluoride, chlorotrifluoroethylene, etc.) and fluoropropylene (hexafluoropropylene (hereinafter also referred to as "HFP"), 2-hydropentafluoropropylene, etc.).

[0062] The aforementioned fluoroalkylethylene is preferably a monomer in which n is from 2 to 6, and a monomer in which n is from 2 to 4 is more preferred. Furthermore, a monomer in which X is a fluorine atom and Y is a hydrogen atom, i.e., a (perfluoroalkyl)ethylene, is particularly preferred.

[0063] Specific examples of the aforementioned fluoroalkylethylene include CH2=CHCF2CF3, CH2=CHCF2CF2CF2CF3 ((perfluorobutyl)ethylene, hereinafter also referred to as “PFBE”), CH2=CFCF2CF2CF2CF3, CH2=CFCF2CF2CF2H and CH2=CFCF2CF2CF2CF2H.

[0064] Specific examples of the aforementioned fluorovinyl ether include CF2=CFOCF3, CF2=CFOCF2CF3, CF2=CFO(CF2)2CF3 (perfluoropropyl vinyl ether, hereinafter also referred to as "PPVE"), CF2=CFOCF2CF(CF3)O(CF2)2CF3, CF2=CFO(CF2)3O(CF2)2CF3, CF2=CFO(CF2CF(CF3)O)2(CF2)2CF3, CF2=CFOCF2CF(CF3)O(CF2)2CF3, CF2=CFOCF2CF=CF2 and CF2=CFO(CF2)2CF=CF2. Of the foregoing, one monomer, which is a diene, is a cyclopolymerizable monomer.

[0065] Furthermore, the aforementioned fluorovinyl ether may contain a functional group.

[0066] Specific examples of the aforementioned fluorovinyl ether with a functional group include CF2=CFO(CF2)3CO2CH3, CF2=CFOCF2CF(CF3)O(CF2)3CO2CH3 and CF2=CFOCF2CF(CF3)O(CF2)2SO2F.

[0067] Specific examples of the aforementioned fluorinated monomer with an alicyclic structure include perfluoro(2,2-dimethyl-1,3-dioxol), 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxol and perfluoro(2-methylene-4-methyl-1,3-dioxolane).

[0068] The monomer without a fluorine atom can be an olefin, a vinyl ester, a vinyl ether, an unsaturated acid anhydride, etc.

[0069] Specific examples of the aforementioned olefin include propylene and isobutene.

[0070] Specific examples of the aforementioned vinyl ester compound include vinyl acetate.

[0071] Specific examples of the aforementioned vinyl ether compound include ethyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether, and hydroxybutyl vinyl ether.

[0072] Specific examples of the aforementioned unsaturated acid anhydride include maleic anhydride, itaconic anhydride, citraconic anhydride and 5-norbornene-2,3-dicarboxylic anhydride (“himic anhydride”).

[0073] The third monomer can be a single type, or two or more types can be used in combination.

[0074] The third monomer, with a view to easily adjusting the crystallinity, is a fluoroalkylethylene, which is represented by X(CF2) n Where CY=CH2 is represented, HFP, PPVE, or vinyl acetate is preferred; with regard to excellent tensile strength and elongation at high temperature (especially at about 180 °C), HFP, PPVE, CF3CF2CH=CH2, or PFBE is more preferred; and PFBE is particularly preferred. That is, as ETFE, a copolymer having TFE units, E units, and PFBE units is particularly preferred.

[0075] In ETFE (I) the molar ratio of TFE units to E units (TFE units / E units) is 45 / 55 to 65 / 35, preferably 50 / 50 to 65 / 35, particularly preferably 50 / 50 to 60 / 40, with regard to excellent heat resistance and mechanical strength of the ETFE.

[0076] In ETFE (I), the proportion of the third units to the total of the TFE units and the E units is preferably from 0.5 to 10.0 mol%, more preferably from 1.0 to 8.0 mol%, and particularly preferably from 1.2 to 4.0 mol%, with regard to excellent heat resistance and mechanical strength of the ETFE.

[0077] In the total of all units in the ETFE, the total of TFE units, E units and third units is 100 mol-%.

[0078] The ETFE film (I) can be a film composed solely of resin components, or it can contain additional components. Specific examples of such additional components include various additives, such as a lubricant, an antioxidant, an antistatic agent, a plasticizer, a mold release agent, etc. One of these additives can be used alone, or two or more can be used in combination.

[0079] In a case where the ETFE film (I) is used as a separating film for the manufacture of a semiconductor device, the ETFE film (I) preferably contains no other components, so that it is less likely to contaminate the mold or the housing.

[0080] The ETFE film (I) is preferably a single-layer film.

[0081] The surface of the ETFE film (I) may be smooth or may have formed irregularities, or one surface may be smooth and the other surface may have formed irregularities.

[0082] If irregularities are present, the surface shape can be one in which some or all of the protrusions and depressions are statistically distributed, or one in which some or all of the protrusions and depressions are regularly arranged. The shapes and sizes of the protrusions and depressions can be the same or different.

[0083] The protrusions can be elongated ribs extending across the surface of a separating film, scattered protrusions, etc., and the depressions can be elongated grooves extending across the surface of a separating film, scattered holes, etc.

[0084] The shapes of the ribs or grooves can be lines, curves, curved forms, etc. A plurality of ribs or grooves can be parallel on the surface of a release film, forming stripes. The cross-sectional shape of the ribs or grooves can be polygonal in a direction perpendicular to the longitudinal direction, such as triangular (V-shaped), semicircular, etc.

[0085] The shape of the protrusions or holes can be a polygonal pyramid, such as triangular pyramidal, square pyramidal, hexagonal pyramidal, etc., conical, hemispherical, polyhedral, or various undefined shapes, etc.

[0086] In a case where the ETFE film (I) is to be used as a release liner for the manufacture of a semiconductor device, the arithmetic mean roughness Ra of the surface of the ETFE film (I) that is to be in contact with the molding tool at the time of forming a resin encapsulation section is preferably from 0.2 to 2.5 µm, and more preferably from 0.2 to 2.0 µm. If the arithmetic mean roughness Ra is at least the lower limit in the aforementioned range, it is less likely that the aforementioned surface and the molding tool will cause blockage, thus reducing the likelihood of wrinkles forming due to blockage. Furthermore, the separability of the ETFE film (I) from the molding tool will be even better. If the arithmetic mean roughness Ra is at most 2.5 µm, it is less likely that small holes will form in the release liner.

[0087] The thickness of the ETFE film (I) is preferably from 50 to 100 µm, more preferably from 50 to 75 µm. If the thickness of the ETFE film (I) is at least the lower limit in the aforementioned range, handling the ETFE film (I) (e.g., handling from roll to roll) will be easy, and wrinkles will be less likely to form when the ETFE film (I) is positioned to cover the mold cavity during drawing. If the thickness of the ETFE film (I) is at most 100 µm, the ETFE film (I) will be easily deformable and will exhibit excellent mold followability.

[0088] If the crystallinity and the proportion of the quasicrystalline layer are within the aforementioned ranges, the ETFE film (I) will exhibit excellent stretchability and be less prone to tearing when stretched under stress. Furthermore, the residual displacement after the stress is removed will be low. Because the residual displacement is low, wrinkles are less likely to form during stretching and retraction. For example, in the fabrication of a semiconductor device by compression molding, wrinkles of the release film in contact with the mold are reduced compared to conventional practice when the ETFE film (I) is arranged as a release liner in a mold, followed by encapsulation with a curable resin. For example, entanglement of the release liner with the housing, which would make it inseparable, can be prevented.

[0089] In the ETFE film (I), the proportion of the crystalline layer (crystallinity) is high, and the proportion of the quasi-crystalline layer within the crystalline layer is also high, compared to a conventional ETFE film used as a release liner. The quasi-crystalline layer exhibits a good balance of rigidity and flexibility and thus acts as a pseudo-crosslinked structure, which is expected to result in high stretchability of the film.

[0090] Furthermore, the residual displacement is lower, which means that at the time of manufacture, as a superstructure of a so-called air sheet structure, in which air is introduced between two sheets that are joined together, it is less likely that the sheets will tear, even if they are inflated by introducing air between them, and when air is released, the sheets will shrink and can consequently be reused.

[0091] Furthermore, since the residual displacement is lower when used as a film for a greenhouse, it is easy to avoid the phenomenon of the film being stretched by water that has accumulated on the film due to rain, etc., and when the water is removed, it quickly returns to its original tension.

[0092] The present invention also relates to an ETFE film obtained by using a mixture of ETFE (A) and ETFE (B) combined in the mass ratio mentioned above. Such an ETFE film is hereinafter referred to as “ETFE film (II)”. In ETFE film (II), wrinkles are less likely to form when it is stretched and retracted.

[0093] In ETFE foil (II), ETFE (B) is less likely to crystallize than ETFE (A) because the content of the third unit is high. At the time ETFE (A) crystallizes, ETFE (B) penetrates, thus inhibiting the crystallization of ETFE (A). This inhibits the growth of the fully crystalline layer and increases the proportion of the quasi-crystalline layer. Consequently, the resulting ETFE foil is expected to have a high proportion of the crystalline layer (crystallinity) and a high proportion of the quasi-crystalline layer within the crystalline layer. This makes it less likely that wrinkles will form when the foil is stretched and retracted.

[0094] The ETFE film (II) preferably has the same crystallinity and the same proportion of the quasicrystalline layer as the ETFE film (I). That is, the ETFE film (II) is preferably the ETFE film (I). (ETFE (A))

[0095] The ETFE (A) has TFE units, E units and third units based on a monomer different from tetrafluoroethylene and ethylene, wherein the monomer different from tetrafluoroethylene and ethylene is a fluoroalkylethylene given by the formula X(CF2) n CY=CH2 is represented, where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer from 2 to 8.

[0096] In ETFE (A) the molar ratio of TFE units to E units (TFE units / E units) for excellent heat resistance and mechanical strength of ETFE is 45 / 55 to 65 / 35, preferably 50 / 50 to 65 / 35, particularly preferably 50 / 50 to 60 / 40.

[0097] In ETFE(A), the proportion of third units to the total TFE and E units is 0.5 to 1.5 mol%, preferably 0.8 to 1.5 mol%, and particularly preferably 1.0 to 1.5 mol%. When the proportion of third units is at most 1.5 mol%, ETFE(A) tends to crystallize readily, and there is a tendency for a fully crystalline layer to form easily. Therefore, the crystallinity of the film containing these units can be made high, for example, at least 55%. Furthermore, the film will also exhibit excellent heat resistance. When the proportion of third units is at least 0.5 mol%, the film will also exhibit excellent mechanical strength.

[0098] In the total of all units in ETFE (A), the total of TFE units, E units and third units is 100 mol-%.

[0099] The MFR of ETFE (A) is preferably 2 to 40 g / 10 min, more preferably 5 to 30 g / 10 min, and particularly preferably 10 to 20 g / 10 min, with a view to improving the formability of ETFE and achieving excellent mechanical strength of the ETFE film. (ETFE (B))

[0100] ETFE (B) has TFE units, E units and third units based on a monomer other than tetrafluoroethylene and ethylene, wherein the monomer other than tetrafluoroethylene and ethylene is a fluoroalkylethylene given by the formula X(CF2) n CY=CH2 is represented, where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer from 2 to 8.

[0101] The molar ratio of TFE units to E units in ETFE (B) is from 45 / 55 to 65 / 35, as in ETFE (A), and the preferred ranges are also the same as in ETFE (A).

[0102] In ETFE(B), the proportion of third-party units to the total TFE and E units is 3.5 to 6 mol%, preferably 3.5 to 5.5 mol%, and particularly preferably 3.5 to 4.5 mol%. When the proportion of third-party units is at least 3.5 mol%, ETFE(B) tends to crystallize very little. Therefore, when forming a film by combining ETFE(B) with ETFE(A), the crystallization of ETFE(A) by ETFE(B) is inhibited, thus suppressing the growth of the fully crystalline layer and promoting the growth of the quasi-crystalline layer. Consequently, for example, an ETFE film can be obtained in which the proportion of the quasi-crystalline layer is at least 10% and the crystallinity is at most 70%. If the proportion of third-party units is at most 5.5 mol%, the heat resistance of the ETFE film will be excellent.

[0103] In total, all units in ETFE (B) include TFE units, E units and third units, totaling 100 mol-%.

[0104] The preferred range of the MFR of ETFE (B) is the same as that of ETFE (A). (Mass ratio of ETFE (A) to ETFE (B))

[0105] The mass ratio of ETFE (A) to ETFE (B) (ETFE (A) / ETFE (B)) is from 80 / 20 to 95 / 5, preferably from 85 / 15 to 95 / 5, particularly preferably from 90 / 10 to 95 / 5.

[0106] If ETFE (A) constitutes at least 80 parts by mass to 100 parts by mass in the total composition of ETFE (A) and ETFE (B), the crystallinity at the time of obtaining a film by forming a mixture of ETFE (A) and ETFE (B) will be high and will be, for example, at least 55%.

[0107] Furthermore, if ETFE (B) comprises at least 5 parts by mass up to 100 parts by mass in the total composition of ETFE (A) and ETFE (B), the crystallization of ETFE (A) during the formation of a film by forming a mixture of ETFE (A) and ETFE (B) is inhibited by ETFE (B), the growth of the fully crystalline layer is suppressed, and the quasi-crystalline layer grows. Consequently, for example, an ETFE film can be obtained in which the proportion of the quasi-crystalline layer is 10 to 20% and the crystallinity is at most 70%.

[0108] If ETFE (B) exceeds 20 to 100 parts by mass in the total of ETFE (A) and ETFE (B), there is a tendency to make it difficult to make ETFE (A) and ETFE (B) compatible, the crystallization of ETFE (A) tends not to be sufficiently inhibited by ETFE (B), and there is a possibility that the quasi-crystalline layer will not grow sufficiently.

[0109] The ETFE film (II) can be composed solely of ETFE (A) and ETFE (B), or it can furthermore contain various ETFE components in addition to ETFE (A) and ETFE (B). In a case where the ETFE film is used as a separating film for the manufacture of a semiconductor device, it is preferable, with a view to reducing contamination of the mold or housing, that no further components are included.

[0110] The ETFE film (II) is preferably a single-layer film.

[0111] The surface of the ETFE film (II) may be smooth, or it may have formed irregularities, or one surface may be smooth while the other surface may have formed irregularities.

[0112] With regard to excellent separability when the ETFE film (II) is used as a separating film for the manufacture of a semiconductor device as described above, it is preferred that irregularities are formed.

[0113] In a case where the ETFE film (II) is used as a separating film for the manufacture of a semiconductor device, the preferred arithmetic mean roughness Ra of the surface of the ETFE film (II) that is in contact with the forming tool at the time of forming the resin encapsulation section is identical to that of the ETFE film (I).

[0114] The preferred thickness range of the ETFE film (II) is identical to that of the ETFE film (I). (Method for the production of an ETFE film (II))

[0115] An ETFE film (II) can be produced by extruding a molten mixture of ETFE (A) and ETFE (B) in the mass ratio mentioned above into a film form using an extruder, followed by cooling.

[0116] Such production of the ETFE film (II) can be carried out, for example, using a production device equipped with an extrusion forming device, a cooling device, such as cooling rollers, and a winding roller.

[0117] The extrusion forming device is used for melting ETFE and continuously extruding it from a die at an optional extrusion speed. The die forms the molten ETFE into a film, etc., and a flat die (T-die), etc., can be used. The extrusion forming device is not specifically limited to any particular type and can utilize a known extrusion device, such as a single-screw or twin-screw extruder.

[0118] The ETFE (A) and ETFE (B) to be fed to the extrusion die can be a mixture that has been melt-mixed beforehand, or ETFE (A) and ETFE (B) that have not been pre-mixed can be fed to the extrusion die and melt-mixed therein. Preferably, the ETFE (A) and ETFE (B) are melt-mixed and granulated beforehand, and the resulting granules are fed to an extrusion die to produce a film.

[0119] Preferably, a cooling roller with an adjustable surface temperature is used. As described later, it is also possible to carry out gradual cooling using two or more cooling rollers.

[0120] The melting point and cooling temperature can be optionally set.

[0121] Additives other than ETFE may be added in advance to ETFE (A), ETFE (B) or a mixture thereof that is to be fed to the extrusion die, so that such further additives can be fed together to the extrusion die.

[0122] However, the method for producing the ETFE film (II) is not limited thereto and, with the exception that ETFE, ETFE (A) and ETFE (B) are used in the aforementioned ratio, the film can be produced by a known method.

[0123] The present invention further describes a method for producing an ETFE film by two-stage cooling, whereby a film can be produced in which the formation of wrinkles during stretching and retraction is less likely. This manufacturing method is preferred as a method for producing ETFE film (I), but is not limited thereto, and is also suitable as a method for producing ETFE film (II) or any other ETFE film.

[0124] The manufacturing process of an ETFE film by this two-stage cooling is also referred to below as the ‘manufacturing process (i)’.

[0125] In the manufacturing process (i), ETFE used as the starting material is not specifically restricted.

[0126] In the ETFE, the molar ratio of TFE units to E units (TFE units / E units) is preferably 45 / 55 to 65 / 35, more preferably 50 / 50 to 65 / 35, and particularly preferably 50 / 50 to 60 / 40, with regard to excellent heat resistance and mechanical strength of the ETFE.

[0127] In the ETFE, the proportion of third units to the total of TFE units and E units is preferably 0.5 to 10.0 mol%, more preferably 1.0 to 8.0 mol%, and particularly preferably 1.2 to 4.0 mol%, with regard to excellent heat resistance and mechanical strength of the ETFE.

[0128] The total of all units in ETFE, including TFE units, E units, and third units, amounts to 100 mol-%.

[0129] The ETFE used as a starting material can be of one type or two or more types. For example, as is the case with the specific mixture mentioned above, which comprises ETFE(A) and ETFE(B), two or more types of copolymers can be used as a mixture. In a case where ETFE is composed of two or more types, it is preferred, in the totality of all units in the ETFE, that the proportion of third-party units to the totality of TFE units and E units is, on average, within the range mentioned above.

[0130] In the case of using a mixture of two types as ETFE, Tc is a value determined by the following formula (3), and Tm is a value determined by the following formula (4). Tc(°C)=[Tc of ETFE(A))×(Mass fraction (%) of ETFE(A) in the ETFE) / 100]+[Tc of(ETFE(B))×(Mass fraction (%) of ETFE(B) in the ETFE / 100)] Tm(°C)=[Tm of ETFE(A))×(Mass fraction (%) of ETFE(A) in the ETFE) / 100]+[Tm of(ETFE(B))×(Mass fraction (%) of ETFE(B) in the ETFE / 100)]

[0131] Additives other than ETFE can be added in advance to the ETFE that is fed to the extrusion die, or additives can be fed to the extrusion die together with ETFE.

[0132] In the manufacturing process (i) of the present invention, the first cooling device can be, for example, a roller (cooling roller) in which the surface temperature can be adjusted. The cooling device for the primarily cooled product, i.e., the second cooling device, can be, for example, a cooling roller, an air doctor blade, or immersion in water (a water tank, etc.). Cases are described below in which the first cooling device is a cooling roller (hereinafter referred to as the "first cooling roller"), and the second cooling device is a cooling roller (first embodiment), an air doctor blade (second embodiment), or a water tank (third embodiment). (First embodiment)

[0133] A manufacturing device 10 in the Fig.1 comprises a nozzle 11 in an extrusion die (not shown), a first cooling roller 13 (first cooling device), a cooling roller 15 (hereinafter referred to as the "second cooling roller") as a second cooling device and a winding roller 17.

[0134] Nozzle 11 is a nozzle for shaping the molten ETFE into a foil shape, etc., and can be a flat T-nozzle, etc.

[0135] The extrusion die, which includes the nozzle 11, is used to melt the ETFE and continuously extrude it from the nozzle 11 at an optional extrusion speed. The extrusion die is not specifically limited, and a known extrusion device, such as a single-screw or twin-screw extruder, can be used.

[0136] The first cooling roller 13 is a cooling roller whose surface temperature can be adjusted. A known cooling roller can be used as the first cooling roller 13, for example, a roller equipped with an inner cylinder that can be attached to the rotating shaft and an outer cylinder located outside the inner cylinder, in which a heat transfer medium (coolant) is distributed or retained between the inner and outer cylinders.

[0137] The second cooling roller 15 can be called the same cooling roller as the first cooling roller 13.

[0138] In the manufacturing device 10, an ETFE film is produced using the following method.

[0139] The ETFE is fed to the extrusion die (not shown) and melted by heating to a temperature of at least Tm of ETFE. The melt 1 is continuously fed to the die 11 and extruded into a film form. The extruded melt 1 in film form is drawn off to the first cooling roller 13, which is located below the die 11, and moved along the rotating first cooling roller 13, resulting in a primarily cooled product.

[0140] The primary cooled product obtained is detached from the first cooling roller 13 and brought into contact with the second cooling roller and further cooled, so that an ETFE film 3 is obtained.

[0141] The ETFE film 3 obtained is wound up into a roll form by the winding roller 17.

[0142] For melting ETFE, the temperature in the extrusion die is at least Tm of the supplied ETFE, preferably at least (Tm of ETFE + 10 °C) and at most (Tm of ETFE + 150 °C), and particularly preferably at least (Tm of ETFE + 20 °C) and at most (Tm of ETFE + 100 °C). If the temperature in the extrusion die is at least Tm of ETFE, a homogeneous melt is obtained, enabling stable extrusion. If the temperature in the extrusion die is at most (Tm of ETFE + 100 °C), material degradation due to thermal decomposition can be prevented.

[0143] The preferred temperature range in nozzle 11 is accordingly.

[0144] The air gap between the nozzle 11 and the first cooling roller 13 (the shortest distance between the outlet of the nozzle 11 and the first cooling roller 13) is preferably at most 100 mm, more preferably at most 50 mm. If the air gap is at most 100 mm, the time for the melt 1 extruded from the nozzle 11 until contact with the first cooling roller 13 will be sufficiently short, thus preventing the temperature of the melt 1 from exceeding Tc of the ETFE before contact with the first cooling roller 13. This makes it less likely that the fully crystalline layer will grow and makes it easier to obtain a low-crystallinity ETFE film.

[0145] The melt 1, which is in contact with the first cooling roller 13, is cooled to the surface temperature of the first cooling roller 13 as it moves along the rotating first cooling roller 13 and is kept at this temperature, so that it becomes a primarily cooled product.

[0146] The surface temperature of the first cooling roller 13 is greater than Tc and less than Tm of ETFE, preferably at least (Tc of ETFE + 2 °C) and at most (Tm of ETFE - 1 °C), more preferably at least (Tc of ETFE + 4 °C) and at most (Tm of ETFE - 1 °C).

[0147] Furthermore, the state in which the melt 1 and the first cooling roller 13 are in contact is maintained for a predetermined time (hereinafter also referred to as the "retention time"). That is, the retention time is a predetermined holding period from the moment the melt 1 is first brought into contact with the first cooling roller 13 until it is detached from the first cooling roller 13. The retention time can advantageously be set such that the fully crystalline layer and the quasi-crystalline layer grow sufficiently and the primarily cooled product is less likely to "sag," i.e., detach from the first cooling roller. The retention time is preferably from 3 to 20 seconds, more preferably from 3 to 15 seconds, and most preferably from 5 to 12 seconds.

[0148] If the surface temperature of the first cooling roll 13 is greater than Tc and less than Tm of ETFE, and the retention time is at least 3 seconds, the fully crystalline layer and the quasi-crystalline layer can grow sufficiently to obtain an ETFE film with a crystallinity of at least 55% and a quasi-crystalline layer fraction of at least 10%. If the surface temperature of the first cooling roll 13 is greater than Tc and less than Tm of ETFE, and the retention time is at most 20 seconds, an ETFE film with a crystallinity of at most 75% and a quasi-crystalline layer fraction of at most 20% can be obtained. Furthermore, it is less likely that "sagging" will occur, in which the primarily cooled product is detached from the first cooling roll.

[0149] If the surface temperature of the first cooling roller 13 is less than Tc of ETFE in the aforementioned range, the quasicrystalline layer will not grow sufficiently, resulting in a low proportion of the quasicrystalline layer in the available ETFE film and a crystallinity that may exceed 75%.

[0150] The primary cooled product obtained is removed by the first cooling roller 13 and cooled by the second cooling roller 15, resulting in an ETFE film 3.

[0151] The cooling conditions at this point are set such that the temperature of the available ETFE film 3, i.e., the temperature of the primarily cooled product after cooling (hereinafter also referred to as the "cooling temperature"), is at least (Tm of ETFE - 120 °C) and at most (Tm of ETFE - 80 °C) within a predetermined time from the time of detachment from the first cooling roller 13. The cooling temperature is preferably at least 150 °C and at most (temperature of the first cooling roller 13 - 120 °C), more preferably at least 180 °C and at most (temperature of the first cooling roller 13 - 130 °C).

[0152] Regarding the second cooling roller 15, the distance from the first cooling roller 13 and the surface temperature can be adjusted so that the primarily cooled product can be cooled to at least (Tm of ETFE - 120 °C) and at most (Tm of ETFE - 80 °C) within 1 second from the time of release.

[0153] The surface temperature of the second cooling roller 15 is preferably at least (surface temperature of the first cooling roller 13 - 180 °C) and at most (surface temperature of the first cooling roller 13 - 120 °C). If the surface temperature of the second cooling roller 15 is within this range, the temperature of the film can be adjusted within a suitable range immediately after cooling, while the surface temperatures of the first cooling roller 13 and the second cooling roller 15 remain constant.

[0154] The time required for cooling to the aforementioned cooling temperature by the second cooling roller 15, from the moment the primarily cooled product has been detached from the first cooling roller 13 (hereinafter also referred to as the "cooling time"), can advantageously be set such that sufficient cooling can be carried out and the fully crystalline layer and the quasi-crystalline layer can be fixed. The cooling time is preferably within 1 second, preferably within 0.5 seconds, and particularly preferably within 0.2 seconds.

[0155] By quenching to the aforementioned cooling temperature for the aforementioned cooling time, the fully crystalline layer and the quasi-crystalline layer that have grown can be fixed. If the cooling temperature is higher than (Tm of ETFE - 80 °C), the cooling will be insufficient, and there is a possibility that the quasi-crystalline layer will transform into the fully crystalline layer.

[0156] If, on the other hand, the cooling temperature is lower than (Tm of ETFE - 120 °C), it is rapidly cooled from the molten state, so that the crystallization itself, which comprises the fully crystalline layer, hardly takes place and the crystallinity tends to be too low.

[0157] The distance from the position for detaching the primarily cooled product from the first cooling roller 13 to the second cooling roller 15 is preferably from 2 to 10 cm, particularly preferably from 2 to 5 cm.

[0158] Whether the primarily cooled product has been quenched to the aforementioned cooling temperature can be confirmed by installing a non-contact temperature sensor (M1241-IR14-790-T10SF-C3 series (wavelength 7.9 µm), manufactured by Shiro Co., Ltd., etc.) at the position where the primarily cooled product is located after the specified cooling time (e.g., after 1 second) from detachment from the first cooling roller 13, and measuring the surface temperature of the ETFE film. If the surface temperature of the ETFE film is at the aforementioned cooling temperature, it can be assumed that it has been quenched. (Second embodiment)

[0159] A manufacturing device 20 in the Fig.2 comprises a nozzle 11 in an extrusion die (not shown), a first cooling roller 13 (first cooling device), an air doctor blade 25 (second cooling device) and a winding roller 17.

[0160] The manufacturing device 20 is identical to the manufacturing device 10, except that an air doctor blade 25 is provided instead of the second cooling roller 15.

[0161] A well-known air squeegee can be used as the air squeegee 25.

[0162] The manufacturing device 20 produces an ETFE film by the following method.

[0163] The primary cooling is carried out in the same manner as described above, and then the primary cooled product obtained is detached from the first cooling roller 13 and further cooled by the air doctor blade 25, so that an ETFE film 3 is obtained.

[0164] The ETFE film obtained is wound up into a roll form by the winding roller 17.

[0165] The production of an ETFE film in the second embodiment can be carried out in the same way as in the first embodiment, with the exception of cooling the primarily cooled product by the air doctor blade 25 instead of bringing it into contact with the second cooling roller 15.

[0166] Cooling by the air scraper 25 is carried out by blowing a laminar airflow onto the primarily cooled product.

[0167] The cooling conditions at this time are set so that the temperature of the available ETFE film 3 (the cooling temperature) is at least (Tm - 120 °C) and at most (Tm - 80 °C) within a specified cooling time.

[0168] The preferred ranges for cooling temperature and cooling time are identical to those in the first embodiment.

[0169] The temperature of the air blown by the air scraper 25 is preferably at most 80 °C, particularly preferably at most 70 °C.

[0170] The airflow velocity blown by the air blade 25 is preferably from 10 to 20 m / s, more preferably from 12 to 18 m / s. If the airflow velocity is at least 10 m / s, the time required to cool the primarily cooled product to the desired temperature will be sufficiently short. If the airflow velocity is at most 20 m / s, fluttering of the primarily cooled product can be prevented.

[0171] The distance from the position for detaching the primarily cooled product from the first cooling roller 13 to the air scraper 25 is preferably from 2 to 15 cm, particularly preferably from 3 to 10 cm.

[0172] In this embodiment, as in the first embodiment, it can be confirmed whether the primarily cooled product has been quenched to the aforementioned cooling temperature or not by installing a non-contact temperature sensor for plastic film measurement at the position where the primarily cooled product is located after a predetermined cooling time from the first cooling roller 13, and by measuring the surface temperature of the film. The preferred ranges for the retention time and the cooling time are identical to those in the first embodiment. (Third embodiment)

[0173] A manufacturing device 30 in the Fig. 3 comprises a nozzle 11 in an extrusion die (not shown), a first cooling roller 13 (first cooling device), and a plurality of guide rollers 31 and 33, a water tank 35 (second cooling device) and a winding roller 17.

[0174] The water tank 35 contains water for cooling the primarily cooled product.

[0175] The manufacturing device 30 is identical to the manufacturing device 10, except that a water tank 35 is provided instead of the second cooling roller 15 and furthermore a plurality of guide rollers 31 and 33 are provided.

[0176] The manufacturing device 30 produces an ETFE film using the following method.

[0177] The primary cooling is carried out in the same manner as described above, and then the primary cooled product obtained is separated from the first cooling roller 13 by the guide roller 31, introduced into the water tank 35 by the guide roller 33 and immersed in the water in the water tank 35 and thereby further cooled, so that an ETFE film 3 is obtained.

[0178] The ETFE film obtained is wound up into a roll form by the winding roller 17.

[0179] The production of an ETFE film in the third embodiment can be carried out in the same way as in the first embodiment, except that the primarily cooled product is cooled by immersing it in water in the water tank 35 instead of bringing it into contact with the second cooling roller 15.

[0180] The cooling conditions at that time are set such that the temperature of the available ETFE film 3 (the cooling temperature) is at least (Tm - 120 °C) and at most (Tm - 80 °C) within a predetermined cooling time. The preferred ranges for the cooling temperature and cooling time are identical to those in the first embodiment.

[0181] The time from the release of the primarily cooled product from the first cooling roller 13 until its entry into the water in the water tank 35 is preferably within one second. If the time exceeds one second, the temperature of the primarily cooled product drops before immersion in the water, making it likely that the resulting crystal will be large. To ensure that the primarily cooled product is easily introduced into the water tank 35, the distance from the release point of the primarily cooled product from the first cooling roller 13 to the water tank 35 is preferably at most 15 cm, more preferably 3 to 15 cm, and particularly preferably 3 to 12 cm.

[0182] The temperature of the water in the water tank 35 is preferably at most 80 °C, particularly preferably at most 70 °C.

[0183] The time during which the primarily cooled product is immersed in the water in the water tank 35 is preferably at least 3 seconds.

[0184] In this embodiment, the primarily cooled product is detached from the first cooling roller 13, then immersed in the water tank 35 within a predetermined time and removed into the air at a position one second after immersion in the water tank 35. At this position, the surface temperature of the film is measured by a non-contact temperature sensor for plastic films. If the film surface temperature is at the aforementioned cooling temperature, it can be determined that it has been quenched.

[0185] The manufacturing process (i) has been described above with reference to the first to third embodiments; however, the present invention is not limited to the embodiments described above. The respective structures of the above embodiments and their combinations are exemplary, and additions, omissions, substitutions, and other modifications of the structure are possible within a range that does not deviate from the concept of the present invention.

[0186] For example, although examples have been shown in which the cooling of the primarily cooled product is carried out by contact with a cooling roller, an air scraper or by immersion in water, other cooling processes may be used.

[0187] In the manufacturing apparatus 10, 20, and 30, a press roller can be arranged in the vicinity of the nozzle 11, or electrostatic holding can be performed to ensure that the melt extruded from the nozzle 11 is in close contact with the surface of the first cooling roller 13. For electrostatic holding, electrodes are provided, and by applying a voltage to the electrodes, a static electricity is generated. This static electricity brings the melt and the first cooling roller into close contact. The electrodes increase the adhesion between the melt and the first cooling roller 13, thereby reducing temperature variations.

[0188] In the manufacturing apparatus 10, 20 and 30, a chamber with an adjustable temperature can be arranged in the vicinity of the nozzle outlet 11, and the first cooling roller 13 can be arranged in this chamber. In such a case, by setting the temperature in the chamber to at least Tc and at most Tm of ETFE, the temperature of the melt 1 is prevented from exceeding Tc during the period from the nozzle outlet 11 until contact with the first cooling roller 13.

[0189] In the manufacturing apparatus 10, 20 and 30, a master pattern roller with irregularities formed on its surface can be arranged in the vicinity of the nozzle outlet 11, and the melt 1 can pass between the master pattern roller and the first cooling roller 13, so that the irregularities formed on the surface of the master pattern roller are continuously transferred to one side of the melt 1. In such a case, an ETFE film can be obtained that has irregularities formed on one side.

[0190] By the manufacturing process (i) an ETFE film (I) can be produced, i.e., an ETFE film whose crystallinity is 55 to 70% and whose quasicrystalline layer content is 10 to 20%.

[0191] With the manufacturing processes described in patent documents 2 to 4, it is difficult to adjust both the crystallinity and the proportion of the quasi-crystalline layer so that they lie within the aforementioned ranges. Using these processes, if the crystallinity is within the aforementioned range, the proportion of the quasi-crystalline layer will be less than 10%, and if the proportion of the quasi-crystalline layer is within the aforementioned range, the crystallinity will exceed 70%.

[0192] In Example 3 of the EXAMPLES in Patent Document 2, an ETFE film was produced in which two types of ETFE were mixed; however, the extensibility of this ETFE film was low. This is due to the fact that ETFEs with poor crystallizability were mixed together, resulting in insufficient growth of both the fully crystalline and the quasi-crystalline layers.

[0193] Patent document 3 discloses an ETFE film produced by setting the surface temperature of a cooling roller to 80 to 140 °C and blowing hot air at 50 to 160 °C onto the film on this cooling roller; however, the stretchability of this ETFE film was low. It is assumed that this was due to both the roller temperature and the temperature of the hot air being too low, thus preventing the quasi-crystalline layer from growing sufficiently.

[0194] Patent document 4 discloses an ETFE film with low crystallinity and high transparency, but low elongation. This is assumed to be due to an insufficient cooling roller temperature, which prevented the quasi-crystalline layer from growing adequately. [Method for manufacturing a semiconductor device]

[0195] The ETFE film (I), the ETFE film (II) or the ETFE film described above and obtained according to the manufacturing process of the present invention is suitable as a separator film for the manufacture of a semiconductor device (hereinafter also referred to as "separator film") which is to be used, for example, in the following process for the manufacture of a semiconductor device.

[0196] A method for manufacturing a semiconductor device comprises a step of arranging a separating film for manufacturing a semiconductor device on the surface of a mold tool, which is to be in contact with a curable resin, a step of arranging a structure comprising a semiconductor chip and a substrate on which the semiconductor chip is mounted in the mold, filling a space in the mold with a curable resin and curing it to form a resin encapsulation section, thereby obtaining an encapsulated body with the structure and the resin encapsulation section, and includes one step of removing the encapsulated body from the mold tool.

[0197] In such a manufacturing process, the separating film is arranged, for example, during the formation of a resin encapsulation section to cover the surface (hereinafter referred to as the "cavity surface") that forms a cavity of a mold tool, which has the cavity (space) with a shape corresponding to the shape of the resin encapsulation section, and is positioned between the formed resin encapsulation section and the cavity surface of the mold tool, so that the removal of the resulting encapsulated body from the mold tool is simplified.

[0198] During the forming of the resin encapsulation section, the release film can be in close contact with at least part of the semiconductor chip's surface. This makes it possible to prevent the curable resin from entering this area, thus obtaining a semiconductor device in which part of the semiconductor chip remains exposed.

[0199] The semiconductor device can be a transistor, an integrated circuit with an integrated diode, etc., a light-emitting diode or LED with a light-emitting element, etc.

[0200] The package shape of the integrated circuit can be a shape that covers the entire integrated circuit, or a shape that covers a section of the integrated circuit (a section that leaves part of the integrated circuit exposed), and specific examples include BGA (“Ball Grid Array”), QFN (“Quad Flat Non-leaded package”) or SON (“Small Outline Non-leaded package”).

[0201] With regard to productivity, a semiconductor device produced by batch encapsulation and singulation is preferred, and a specific example is an integrated circuit where the encapsulation system is a MAP (“Molded Array Packaging”) system or a WL (“Wafer Label Packaging”) system.

[0202] For the purposes of the present invention, a semiconductor device is preferred in which the thickness of the resin encapsulation section is large, i.e., a semiconductor device in which the depth of the mold cavity is large, and which, for example, can be a NAND flash memory, a power device, or a sensor. The thickness of the resin encapsulation section is preferably from 0.5 to 3.0 mm.

[0203] A known method can be used to manufacture the semiconductor device. The manufacturing conditions can also be the same as in the known method for manufacturing a semiconductor device.

[0204] A compression molding process is preferred as the method for forming the resin encapsulation section. A known compression molding device can be used as the apparatus for this purpose.

[0205] With reference to the Fig. 4, Fig. 5 to Fig. Section 6 describes an embodiment of the method for manufacturing a semiconductor device by a compression molding process.

[0206] The method for manufacturing a semiconductor device in this embodiment comprises the following steps (1) to (5).

[0207] Step (1): In a molding tool comprising a stationary upper molding tool 120, a lower cavity surface element 122, and a frame-shaped movable lower molding tool 124 arranged along the circumference of the lower cavity surface element 122, a step of arranging a separating film 100 such that the separating film 100 covers the cavity 126 of the molding tool, and vacuum suction of the separating film to the side of the lower cavity surface element 122 of the molding tool ( Fig. 4).

[0208] Step (2): A step of filling a curable resin 140 into the cavity 126, the surface of which is covered by the separating film 100, and arranging a structure comprising a substrate 110 and a plurality of semiconductor chips 112 mounted on the substrate 110 at a predetermined position in the cavity 126 ( Fig. 4).

[0209] Step (3): A step of clamping the forming tool ( Fig.5), so that only the lower cavity surface element 122 is lifted and the curable resin 140 is melted and cured, so that a resin encapsulation section 114 is formed for the joint encapsulation of a plurality of semiconductor chips 112 ( Fig. 6), thereby obtaining a jointly encapsulated body comprising the substrate 110, the plurality of semiconductor chips 112 and the resin encapsulation section 114.

[0210] Step (4): A step of removing the jointly encapsulated body from the mold.

[0211] Step (5): A step of cutting the substrate 110 and the resin encapsulation section 114 of the jointly encapsulated body, such that the plurality of semiconductor chips 112 are separated, thereby obtaining semiconductor devices each comprising a substrate 110, at least one semiconductor chip 112 mounted on the substrate 110, and a resin encapsulation section 114 encapsulating the semiconductor chip 112.

[0212] The ETFE film (I) or (II) described above is used as the separating film 100.

[0213] However, the method for manufacturing a semiconductor device is not limited to the above embodiment. In the above embodiment, the respective configurations and their combinations are exemplary, and within a scope that does not deviate from the concept of the present invention, additions, omissions, substitutions, and further modifications of the configurations are possible.

[0214] The timing of arranging the separating film 100 and the curable resin 140 in the cavity 126 can be such that, after the curable resin 140 has been arranged on the separating film 100, the separating film 100 can be arranged in this state so that it covers the cavity 126.

[0215] The point in time when the separating film 100 is vacuum-suspended against the side of the lower cavity surface element 122 of the molding tool can be after the molding tool has been clamped.

[0216] The point in time at which the release film 100 and the jointly encapsulated body are separated is not limited to the point in time at which the jointly encapsulated body is removed from the mold. For example, the jointly encapsulated body can be removed from the mold together with the release film, and then the release film can be separated from the jointly encapsulated body.

[0217] The spacing between the majority of jointly encapsulated semiconductor elements can be uniform or non-uniform. Given that the encapsulation can be carried out homogeneously and the stress exerted on the majority of semiconductor elements is uniform (minimalizing the stress), it is preferred that the spacing between the majority of semiconductor elements be uniform.

[0218] The forming tool is not on a surface in the Fig. 4, Fig. 5 to Fig.The mold shown in Figure 6 is limited, and a known mold can be used as a mold for use in a compression molding process.

[0219] After step (4) or (5), a step of forming a printing ink layer on the surface of the resin encapsulation section 114 can be carried out using a printing ink. In the case of manufacturing a light-emitting diode as a semiconductor device, the resin encapsulation section also acts as a lens unit, and therefore a printing ink layer is not usually formed on the surface of the resin encapsulation section.

[0220] The semiconductor device to be manufactured is not limited to that shown in the preceding embodiment. Depending on the semiconductor device to be manufactured, step (5) need not be performed. The semiconductor device to be encapsulated in the resin encapsulation section can be one or more. The shape of the resin encapsulation section is not limited to that shown in the Fig. The rectangle shown in Figure 6 is limited, and steps, etc., may be present. In a case where the resin encapsulation section is a lens section, various lens shapes can be used as the shape of the resin encapsulation section, such as an essentially hemispherical type, a shell type, a Fresnel lens type, a semi-cylindrical type, a hemispherical lens grouping type, etc. EXAMPLES

[0221] The present invention is described in detail below with reference to examples. However, the present invention is not limited by the following description.

[0222] Of the examples 1 to 28 described below, examples 1 to 5 and 17 to 23 are examples of the present invention and examples 6 to 16 and 24 to 28 are comparative examples.

[0223] The assessment methods and materials used in the respective examples are listed below. [Assessment method](thickness)

[0224] The thickness (µm) of an ETFE film was measured according to ISO 4591: 1992: (JIS K7130: 1999 B1 method, method for measuring the thickness of a sample taken from a plastic film or sheet by a mass method). (Crystallinity and proportion of the quasicrystalline layer)

[0225] The crystallinity and the fraction of the quasicrystalline layer of an ETFE foil were obtained from the integrated intensities of the diffraction peaks obtained by an X-ray diffraction method.

[0226] A sample was prepared by cutting an ETFE film into the following shape. The prepared sample was glued to a quartz plate and mounted on a sample stage, whereupon X-ray diffraction measurements were performed using a powder X-ray diffractometer. Sample shape: A foil with a thickness of 50 µm and a size of 1.5 cm × 1.5 cm Measuring device: D2 PHASER, manufactured by Bruker Co. Measurement method: 2θ / θ method Measuring range: 2θ = 10 to 30° X-ray intensity: 30 kV, 10 mA X-ray source: CuKα radiation Analysis software: TOPAS Ver. 4.2, manufactured by Bruker Co. Measurement temperature: Room temperature (20 to 25 °C)

[0227] The obtained diffraction intensity curve was fitted using analysis software. Using the Pearson vii function, the curve was fitted to ensure that the difference between the fitted curve and the actual curve was at most 10%. A peak separation technique was used to automatically optimize the curve by setting the peak position of the non-crystalline section to 2θ = 17.268° and using the two crystal peaks at 20° and 19° as starting points. The peak's full width at half maximum (FWHM) was also automatically optimized. Two crystal peaks were present, and their respective area fractions were determined.

[0228] From the peak area S 20 in the vicinity of 2θ = 20°, the peak area S 19 in the vicinity of 2θ = 19° and the peak area S 17In the vicinity of 2θ = 17° the crystallinity (%) was obtained by the following formula (1), and the fraction of the quasicrystalline layer was obtained by the following formula (2). Crystallinity(%)=(S19+S20) / (S17+S19+S20)×100 Percentage of quasicrystalline layer (%) = S20 / (S17+S19+S20)×100 (Tearing during shaping, folding during shaping)

[0229] Using an ETFE film produced in each example as a release film, a compression molding test was carried out according to the following procedure under the following conditions.

[0230] The test used a PMC1040 semiconductor encapsulation molding tool (trade name, manufactured by TOWA Corporation). The PMC1040 semiconductor encapsulation molding tool is a device equipped with a [missing information - likely a specific component or component]. Fig.4 is equipped with the forming tool shown (a fixed upper forming tool 120, a lower cavity surface element 122 and a movable lower forming tool 124). <formpressverfahren>

[0231] In the PMC1040 semiconductor encapsulation molding device, a release film (an ETFE film) is unwound from a roll, fixed to a table, and then cut to a predetermined length. A curable resin is then applied to the release film, which is conveyed in this state onto a cavity formed by the lower cavity surface element 122 and the movable lower mold 124. After the release film is positioned on the cavity, the stationary upper mold 120 and the movable lower mold 124 are clamped, and air is extracted by a vacuum pump from vacuum suction holes on the circumferential section of the cavity, so that the release film conforms to the cavity surface and air bubbles are drawn out of the curable resin.The lower cavity surface element 122 is then raised so that a predetermined final depth and clamping force are achieved, and this state is maintained for a predetermined clamping time in order to carry out the compression molding. <formpressbedingungen> Mold temperature: 180 °C Cavity size: 210 mm × 70 mm. Initial depth of the cavity: 1.8 mm. Final depth of the cavity: 0.6 mm. Curable resin: Sumikon EME G770H Type F Ver. GR (manufactured by Sumitomo Bakelite Co., Ltd.). Vacuum level when following cavity surface sequences: -85 kPa. Vacuum level when removing air bubbles from the curing resin: -80 kPa. Time for removing air bubbles from the curing resin: 10 seconds. Clamping time: 150 seconds. Clamping force: 9.8 × 10 4 N.

[0232] After molding, the side surface of the resin encapsulation section was examined to confirm the presence of wrinkles. Furthermore, the film was examined to assess its tear resistance according to the following standards. <Reißen während des Formens> o (Good): A visual inspection did not confirm any small hole in the ETFE foil. × (Bad): A visual inspection confirmed small holes in the ETFE foil. <Falten während des Formens> o (Good): No depression caused by ETFE film penetration was detected on the side surface of the resin encapsulation section. × (Bad): Depressions were found on the side surface of the resin encapsulation section, caused by interference from the ETFE film.

[0233] However, in the case of a film where the result of the assessment of tearing during molding was poor, the resin leaked from the point of tearing the film, and an assessment of wrinkles was difficult, and therefore an assessment of wrinkles was not carried out. [Materials used]

[0234] Resin 1: Copolymer of TFE units / E units / PFBE units = 57.1 / 42.9 / 1.3 (molar ratio) (MFR: 15 g / 10 min, Tc: 241 °C, Tm: 253 °C, manufactured by Daikin Industries Ltd. “EP-526”).

[0235] Resin 2: Copolymer of TFE units / E units / PFBE units = 55.8 / 44.2 / 1.4 (molar ratio) (MFR: 12 g / 10 min, Tc: 243 °C, Tm: 257 °C, synthetic product prepared by the manufacturing example 1 shown below).

[0236] Resin 3: Copolymer of TFE units / E units / PFBE units = 58.5 / 41.5 / 3.7 (molar ratio) (MFR: 15 g / 10 min, Tc: 209 °C, Tm: 222 °C, synthetic product prepared by the manufacturing example 2 shown below).

[0237] Resin 4: Copolymer of TFE units / E units / PFBE units = 58.3 / 41.70 / 7.0 (molar ratio) (MFR: 16.2 g / 10 min, Tc: 183 °C, Tm: 195 °C, synthetic product prepared by the manufacturing example 3 shown below).

[0238] Resin 5: Mixed resin of resin 1 / resin 3 = 95 / 5 (mass ratio) (Tc: 239 °C, Tm: 251 °C).

[0239] Resin 6: Mixed resin of resin 1 / resin 3 = 85 / 15 (mass ratio) (Tc: 236 °C, Tm: 248 °C).

[0240] Resin 7: Mixed resin of resin 2 / resin 3 = 95 / 5 (mass ratio) (Tc: 241 °C, Tm: 255 °C).

[0241] Resin 8: Mixed resin of resin 1 / resin 3 = 75 / 25 (mass ratio) (Tc: 241 °C and 212 °C, Tm: 253 °C and 227 °C).

[0242] Resin 9: Mixed resin of resin 1 / resin 3 = 99 / 1 (mass ratio) (Tc: 241 °C, Tm: 253 °C).

[0243] Resin 10: Mixed resin of resin 1 / resin 2 = 90 / 10 (mass ratio) (Tc: 241 °C, Tm: 253 °C).

[0244] Resin 11: Mixed resin of resin 3 / resin 4 = 90 / 10 (mass ratio) (Tc: 196 °C, Tm: 209 °C).

[0245] Resins 5 to 11 were obtained by mixing the respective resins in the aforementioned mass ratios using the following method for producing a mixed resin.

[0246] Tc and Tm of resins 1 to 4 were each obtained by the aforementioned methods using a scanning differential thermal analyzer (manufactured by SII NanoTechnology, Inc., DSC220CU).

[0247] Regarding resins 5 to 7 and 9 to 11, which are blended resins, Tc was calculated using formula (3) above and Tm was calculated using formula (4) above. For these blended resins, the values ​​of Tc and Tm were obtained using the measurement method described above, employing a scanning differential thermal analyzer, and were consistent with the calculated values.

[0248] In resin 8, the two resins were not uniformly mixed and completely separated, therefore no calculation of Tc according to formula (3) or of Tm according to formula (4) was performed. For these mixed resins, the values ​​of Tc and Tm were obtained using the aforementioned measurement method with a scanning differential thermal analyzer, whereby two values ​​were determined for each. (Production example 1)

[0249] Into a 94 L stainless steel autoclave with vacuum extraction, 107.7 kg of 1-hydrotridecafluorohexane, 41.0 kg of 1,3-dichloro-1,1,2,2,3-pentafluoropropane (trade name “AK225cb”, manufactured by Asahi Glass Co., Ltd., hereinafter also referred to as “AK225cb”) and 0.85 kg of PFBE were introduced and the temperature was increased to 66 °C with stirring, whereupon a mixed gas of monomers of TFE / ethylene = 89 / 11 (molar ratio) was introduced until the pressure reached 1.5 MPaG, and 30.2 g of a 50 wt% tert-butylperoxypivalate AK225cb solution were introduced to initiate polymerization.During polymerization, a mixed gas of TFE / ethylene = 54 / 46 (molar ratio) and PFBE was continuously added at a concentration of 1.4 mol% of the mixed gas, increasing the pressure to 1.5 MPaG. After a total of 7.19 kg of the mixed gas (TFE / ethylene = 54 / 46 molar ratio) had been introduced, the autoclave was cooled and the remaining gas was purged to terminate the polymerization. The polymerization time was 305 minutes. The resulting ETFE slurry was transferred to a 220 L granulation tank, and 77 L of water were added. The mixture was then heated with stirring to remove the polymerization solvent and any remaining monomers, yielding 7.2 kg of granulated resin 2.

[0250] In "MPaG", G indicates that it is an overpressure, and the same applies below. (Production example 2)

[0251] In a 94 L stainless steel autoclave with vacuum extraction, 85.2 kg of 1-hydrotridecafluorohexane, 6.31 kg of AK225cb and 1.22 kg of PFBE were placed and the temperature was increased to 66 °C with stirring, whereupon a mixed gas of TFE / ethylene = 89 / 11 (molar ratio) was introduced until the pressure reached 1.5 MPaG, and 30.2 g of a 50 wt% tert-butylperoxypivalate-AK225cb solution were introduced to initiate the polymerization. During polymerization, a mixed gas of TFE / ethylene (60 / 40 molar ratio) and PFBE (3.8 mol% of the mixed gas) was continuously added until the pressure reached 1.5 MPaG. After a total of 7.19 kg of the mixed gas (60 / 40 molar ratio) had been introduced, the autoclave was cooled and the remaining gas was purged to terminate the polymerization. The polymerization time was 305 minutes.The obtained ETFE slurry was transferred to a 220 L granulation tank and 77 L of water were added, followed by heating while stirring to remove the polymerization solvent and residual monomers, yielding 7.5 kg of a granulated resin 3. (Production example 3)

[0252] In a 94 L stainless steel autoclave with vacuum extraction, 87.3 kg of 1-hydrotridecafluorohexane, 4.21 kg of AK225cb and 2.13 kg of PFBE were placed and the temperature was increased to 66 °C with stirring, whereupon a mixed gas of TFE / ethylene = 89 / 11 (molar ratio) was introduced until the pressure reached 1.5 MPaG, and 60.4 g of a 50 wt% tert-butylperoxypivalate-AK225cb solution were introduced to initiate the polymerization. During polymerization, a mixed gas of TFE / ethylene (60 / 40 molar ratio) and PFBE at a concentration of 7.0 mol% of the mixed gas was continuously added until the pressure reached 1.5 MPaG. After a total of 7.19 kg of the TFE / ethylene mixture (60 / 40) had been introduced, the autoclave was cooled and the remaining gas was purged to terminate the polymerization. The polymerization time was 333 minutes.220 L of the obtained ETFE slurry were transferred to a granulation tank and 77 L of water were added, whereupon the mixture was heated while stirring to remove the polymerization solvent and residual monomers, yielding 7.2 kg of a granulated resin 4. (Method for producing a mixed resin granulate)

[0253] Using a twin-screw extruder with a diameter of 15 mm and L / D (cylinder length / cylinder inner diameter) = 30, two types of resin granules were mixed and fed in a predetermined mass ratio to produce a blended resin granulate. The extruder temperature was set to 320 °C. [Example 1]

[0254] Resin 5 is fed into an extrusion die with a T-nozzle, melted, and extruded through the T-nozzle into a film. This film is then picked up onto the first cooling roll and held in contact with the surface of the first cooling roll for 10 seconds to form an ETFE film with a thickness of 50 µm. The temperature at the melting section and the T-nozzle section of the extruder (hereinafter referred to as the "extrusion temperature") was set to 340 °C; the surface temperature of the first cooling roll was set to 80 °C; the take-off speed was set to 5 m / min; and the air gap between the T-nozzle and the first cooling roll was set to 15 mm. At the time of take-off, the molten resin 5 was held in close contact with the first cooling roll by electrostatic holding.Immediately before contact with the first cooling roller, the surface temperature of the molten resin was 5,330 °C. [Examples 2 to 16]

[0255] An ETFE film with a thickness of 50 µm was obtained in the same way as in Example 1, except that the type of resin, the surface temperature of the first cooling roller, the air gap and the presence or absence of electrostatic holding (contact method with the first cooling roller) were set as shown in Tables 1 and 2. [Example 17]

[0256] Resin 1 was extruded from the same extrusion die as in Example 1 into the form of a film, which was then loaded onto the first cooling roller during electrostatic holding. The film was held in contact with the surface of the first cooling roller for 10 seconds, after which the resulting primarily cooled product was detached from the first cooling roller. It was then brought into contact with the second cooling roller, which had a surface temperature of 100 °C, and consequently cooled to 150 °C, forming an ETFE film with a thickness of 50 µm. The extrusion temperature was set to 340 °C; the surface temperature of the first cooling roller was set to 250 °C; the take-off speed was set to 5 m / min; and the air gap between the T-nozzle and the first cooling roller was set to 15 mm.The temperature of the ETFE film 1 second after the time of peeling (hereinafter referred to as the "film temperature immediately after cooling") was 150°C. [Examples 18 to 28]

[0257] An ETFE film with a thickness of 50 µm was obtained in the same way as in Example 17, except that the type of resin, the nozzle temperature, the surface temperature of the first cooling roller, the type and cooling conditions of the cooling device for cooling the primarily cooled product, and the film temperature immediately after cooling were set as shown in Tables 3 and 4.

[0258] Regarding the ETFE foil obtained in each example, the evaluation results for crystallinity, the proportion of the quasicrystalline layer, wrinkling during forming and tearing during forming are shown in Tables 1 to 4. Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 resin 5 6 5 5 7 1 2 1 Crystallization temperature Tc (°C) 239 236 239 239 241 241 243 241 Melting point Tm (°C) 251 248 251 251 255 253 257 253 Extrusion temperature (°C) 340 340 340 340 340 340 340 340 Air gap (mm) 15 15 15 15 15 15 15 15 Contact method with the first cooling roller Electrostatic holding Electrostatic holding Electrostatic holding None Electrostatic holding Electrostatic holding Electrostatic holding Electrostatic holding Surface temperature (°C) immediately before contact with the first cooling roller 330 330 330 330 330 330 330 330 Surface temperature (°C) of the first cooling roller 80 80 150 80 80 80 80 100 Cooling device for the primarily cooled product No No No No No No No No Cooling conditions - - - - - - - - Film temperature (°C) immediately after cooling 100 100 100 100 100 100 100 120 Crystallinity (%) 60 56 70 68 60 67 67 68 Percentage of quasicrystal 11 11 12 17 11 2 2 6 Tearing during forming ◯ ◯ ○ ○ ◯ ○ ○ ○ Folds during shaping ○ ○ ○ ◯ ◯ × × × Table 2 Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 Example 16 resin 1 1 1 3 8 9 10 11 Crystallization temperature Tc(°C) 241 241 241 209 241 / 212 241 241 196 Melting point Tm (°C) 253 253 253 222 253 / 227 253 253 209 Extrusion temperature (°C) 340 340 340 340 340 340 340 340 Air gap (mm) 15 150 15 15 15 15 15 15 Contact method with the first cooling roller Electrostatic holding Electrostatic holding None Electrostatic holding Electrostatic holding Electrostatic holding Electrostatic holding Electrostatic holding Surface temperature (°C) immediately before contact with the first cooling roller 330 330 330 330 330 330 330 330 Surface temperature (°C) of the first cooling roller 150 80 80 80 80 80 80 100 Cooling device for the primary cooled product No No No No No No No No Cooling conditions - - - - - - - - Film temperature (°C) immediately after cooling 160 100 100 100 100 100 100 100 Crystallinity (%) 83 88 72 50 55 67 67 45 Percentage of quasicrystal 10 10 8 2 4 4 2 1 Tearing during forming × × ◯ × ◯ ◯ ◯ × Folds during shaping - - × - × × × - Table 3 Example 17 Example 18 Example 19 Example 20 Example 21 Example 22 Example 23 resin 1 1 1 2 1 3 8 Crystallization temperature Tc (°C) 241 241 241 243 241 209 241 / 212 Melting point Tm(°C) 253 253 253 257 253 222 253 / 227 Extrusion temperature (°C) 340 340 340 340 340 310 340 Air gap (mm) 15 15 15 15 15 15 15 Contact method with the first cooling roller Electrostatic holding Electrostatic holding Electrostatic holding Electrostatic holding Electrostatic holding Electrostatic holding Electrostatic holding Surface temperature (°C) immediately before contact with the first cooling roller 330 330 330 330 330 300 330 Surface temperature (°C) of the first cooling roller 250 250 250 250 250 210 240 Cooling device for the primarily cooled product Second cooling roller air squeege water tank Second cooling roller Second cooling roller Second cooling roller Second cooling roller Cooling conditions Surface temperature 100 °C Air temperature 60 °C, airflow speed 15 m / min Water temperature 70°C Surface temperature 100 °C Surface temperature 70 °C Surface temperature 90 °C Surface temperature 90 °C Film temperature (°C) immediately after cooling 150 150 150 150 130 120 140 Crystallinity (%) 65 65 65 65 58 55 58 Percentage of quasicrystal 15 15 15 15 17 10 17 Tearing during forming ○ ○ ○ ○ ○ ○ ○ Folds during shaping ○ ○ ○ ○ ○ ○ ○ Table 4 Example 24 Example 25 Example 26 Example 27 Example 28 resin 2 2 1 1 3 Crystallization temperature Tc (°C) 243 243 241 241 209 Melting point Tm (°C) 257 257 253 253 222 Extrusion temperature (°C) 340 340 340 340 310 Air gap (mm) 15 15 15 15 15 Contact method with the first cooling roller Electrostatic holding Electrostatic holding Electrostatic holding Electrostatic holding Electrostatic holding Surface temperature (°C) immediately before contact with the first cooling roller 330 330 330 330 300 Surface temperature (°C) of the first cooling roller 250 230 230 250 200 Cooling device for the primary cooled product No Second cooling roller Second cooling roller Second cooling roller Second cooling roller Cooling conditions - Surface temperature 110°C Surface temperature 110°C Surface temperature 50°C Surface temperature 60°C Film temperature (°C) immediately after cooling 220 150 150 100 100 Crystallinity (%) 90 90 90 50 58 Percentage of quasicrystal 10 10 10 18 3 Tearing during forming ○ × × × ○ Folds during shaping × - - - ×

[0259] As shown in the preceding results, the crystallinity of the ETFE films in Examples 1 to 5 and 17 to 23 ranged from 55 to 70%, and the proportion of the quasi-crystalline layer ranged from 10 to 20%. Furthermore, the evaluation results for wrinkling and tearing during forming were excellent, and they also exhibited excellent stretchability.

[0260] On the other hand, in the ETFE films in Examples 6 to 16 and 24 to 28, where ETFE (A) and ETFE (B) were not used in the ratio within a range of 80 / 20 to 95 / 5 or the surface temperature of the first cooling roller was at most Tc, at least one of the crystallinity and the proportion of the quasi-crystalline layer was outside the aforementioned range. Furthermore, the elongation was poor, resulting in a poor assessment of tearing during forming or, alternatively, a poor assessment of wrinkling during forming.

[0261] In particular, in the ETFE films in Examples 6 to 8, where resin 1 or 2, corresponding to ETFE (A), was used alone and the surface temperature of the first cooling roller was set to a maximum of Tc, there was no component present that inhibited the growth of the fully crystalline layer, and the fully crystalline layer grew more strongly than the quasi-crystalline layer, resulting in a low proportion of the quasi-crystalline layer. Furthermore, the evaluation result for wrinkling during forming was poor.

[0262] In the ETFE film in Example 9, which was produced under the same conditions as in Examples 6 and 8, except that the surface temperature of the first cooling roller was set to a higher temperature than in Examples 6 and 8 (although it was at most Tc), the temperature of the first cooling roller was at most Tc, and it was in contact with the hot roller. This made the growth of the fully crystalline layer more likely and resulted in high crystallinity. Furthermore, the tear resistance during forming was poor.

[0263] In the ETFE film in Example 10, which was produced under the same conditions as in Example 6, except that the air gap was 150 mm, crystallization began before contact with the first cooling roller and it was slowly cooled in air, thus increasing the likelihood of stable crystal growth and resulting in high crystallinity. Furthermore, the tear resistance during forming was poor.

[0264] In the ETFE film in Example 11, which was produced under the same conditions as in Example 6, except that electrostatic holding was omitted, both the crystallinity and the quasicrystal content were high. Furthermore, the evaluation result for wrinkling during forming was poor. This is assumed to be due to the low adhesion between the molten ETFE film and the first cooling roller.

[0265] In the ETFE film in Example 12, where only resin 3, corresponding to ETFE (B), was used and the surface temperature of the first cooling roller was set to a maximum of Tc, significant amounts of monomers different from TFE and ethylene, which inhibit crystallization, were present, resulting in low crystallinity. Furthermore, the tear resistance during forming was poor.

[0266] In the ETFE film shown in Example 13, where resin 8, obtained by mixing resin 1 (corresponding to ETFE(A)) and resin 3 (corresponding to ETFE(B)) in a mass ratio of 75 / 25, was used, and the surface temperature of the first cooling roller was set to 80 °C, the resin corresponding to ETFE(B), which inhibits the growth of the fully crystalline layer, was mixed in too high a proportion. This resulted in ETFE(A) and ETFE(B) being in a completely incompatible state, and the growth of the fully crystalline layer was not sufficiently inhibited, leading to a low proportion of the quasi-crystalline layer. Furthermore, the evaluation result for wrinkling during forming was poor.

[0267] In the ETFE film shown in Example 14, where resin 9, which was a mixture of resins 1 and 3 in a mass ratio of 99:1, was used and the surface temperature of the first cooling roller was set to 80 °C, the amount of ETFE (B) was too low and the growth of the fully crystalline layer was not sufficiently inhibited, resulting in a low proportion of the quasi-crystalline layer. Furthermore, the evaluation result for wrinkling during forming was poor.

[0268] In the ETFE film in Example 15, where resin 10, obtained by mixing resin 1 and resin 2, both corresponding to ETFE(A), was used and the surface temperature of the first cooling roller was set to a maximum of Tc, there was no component present that inhibited the growth of the fully crystalline layer. The surface temperature of the first cooling roller was at most Tc, resulting in strong growth of the fully crystalline layer and a low proportion of the quasi-crystalline layer. Furthermore, the evaluation result for wrinkling during forming was poor.

[0269] In the ETFE film in Example 16, where resin 11, obtained by mixing resin 3 (corresponding to ETFE (B)) and resin 4 (which is neither ETFE (A) nor (B)), was used, and the surface temperature of the first cooling roller was set to 80 °C, a resin with an even lower crystallinity was mixed with a resin that originally had low crystallinity, resulting in low crystallinity and a low proportion of the quasi-crystalline layer. Furthermore, the tear resistance during forming was poor.

[0270] In the ETFE film shown in Example 24, where only resin 2 was used, the initial quenching of the cooled product was not performed, and the film temperature immediately after cooling was higher than Tm - 80 °C. Although the quasi-crystalline layer grew on the first cooling roller, the subsequent tempering process transformed the quasi-crystalline layer into a fully crystalline layer, resulting in high crystallinity. Furthermore, due to the high crystallinity, the ETFE film was brittle, and the evaluation result for wrinkling during forming was poor.

[0271] In the ETFE films shown in Examples 25 and 26, where only resin 2 or 1 was used and the surface temperature of the first cooling roller was set to a maximum of Tc, the temperature of the first cooling roller was at most Tc, and the film was in contact with the roller at high temperature. This made the growth of the complete crystal more likely and resulted in high crystallinity. Furthermore, the tear resistance during forming was poor.

[0272] In the ETFE film shown in Example 27, where only resin 1 was used and the film temperature was set to less than Tm - 120 °C immediately after cooling, the film cooled rapidly from the molten state, making crystallization itself, including complete crystal formation, less likely. This resulted in low crystallinity. Furthermore, the tear resistance during molding was poor.

[0273] In the ETFE film shown in Example 28, where only resin 3 was used and the film temperature was set to less than Tm - 120°C immediately after the primary cooled product had cooled, the proportion of the quasi-crystalline layer was low. Furthermore, the evaluation result for wrinkles during molding was poor. COMMERCIAL APPLICABILITY

[0274] Regarding ETFE film (I), ETFE film (II) and ETFE film obtainable by manufacturing process (i), their respective applications are not specifically limited and specific examples include separating films for the manufacture of semiconductor devices, films for greenhouses, films for accommodations such as tent films, films for chemical storage bags, etc.

[0275] These ETFE films exhibit excellent stretchability and are less likely to tear or wrinkle when stretched, and consequently they are very suitable as separator films for the manufacture of semiconductor devices, particularly as separator films for the manufacture of semiconductor devices by a compression molding process. REFERENCE MARK

[0276] 1: Melt, 3: ETFE film, 10: Manufacturing device, 11: Nozzle, 13: First cooling roller, 15: Second cooling roller, 17: Winding roller, 20: Manufacturing device, 25: Air doctor blade, 30: Manufacturing device, 31 and 33: Guide rollers, 35: Water tank, 100: Release film, 110: Substrate, 112: Semiconductor chip, 114: Resin encapsulation section, 120: Fixed upper mold, 122: Lower cavity surface element, 124: Movable lower mold, 126: Cavity, 140: Curable resin< / formpressbedingungen> < / formpressverfahren>

Claims

[1] Film which is an ethylene tetrafluoroethylene copolymer film, characterized by , that the crystallinity, which is determined by the following formula (1) from the peak area S 20 in the vicinity of 2θ = 20°, the peak area S 19 in the vicinity of 2θ = 19° and the peak area S 17 in the vicinity of 2θ = 17° in the diffraction intensity curve obtainable by an X-ray diffraction method, is from 55 to 70%, and the fraction of the quasicrystalline layer obtainable by the following formula (2) is from 10 to 20%, Crystallinity(%)=(S19+S20) / (S17+S19+S20)×100 Percentage of quasicrystalline layer (%) = S20 / (S17+S19+S20)×100 [2] Slide, characterized by, that it is produced from a mixture of the following ETFE (A) and the following ETFE (B) in a mass ratio of 80 / 20 to 95 / 5, ETFE (A): an ethylene-tetrafluoroethylene copolymer with tetrafluoroethylene units, ethylene units and third units based on a monomer other than tetrafluoroethylene and ethylene, wherein the molar ratio of the tetrafluoroethylene units to the ethylene units is from 45 / 55 to 65 / 35 and the proportion of the third units to the total of the tetrafluoroethylene units and the ethylene units is from 0.5 to 1.5 mol%, wherein the monomer other than tetrafluoroethylene and ethylene is a fluoroalkylethylene described by the formula X(CF2) nCY=CH2, where X and Y are each independently a hydrogen atom or a fluorine atom and n is an integer from 2 to 8, ETFE (B): an ethylene-tetrafluoroethylene copolymer with tetrafluoroethylene units, ethylene units and third units based on a monomer other than tetrafluoroethylene and ethylene, wherein the molar ratio of the tetrafluoroethylene units to the ethylene units is from 45 / 55 to 65 / 35 and the proportion of the third units to the total of the tetrafluoroethylene units and the ethylene units is from 3.5 to 6 mol%, wherein the monomer other than tetrafluoroethylene and ethylene is a fluoroalkylethylene described by the formula X(CF2) n CY=CH2 is represented, where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer from 2 to 8. [3] Film according to claim 2, wherein the crystallinity is determined by the following formula (1) from the peak area S20 in the vicinity of 2θ = 20°, the peak area S 19 in the vicinity of 2θ = 19° and the peak area S 17 in the vicinity of 2θ = 17° in the diffraction intensity curve obtainable by an X-ray diffraction method, is from 55 to 70%, and the fraction of the quasicrystalline layer obtainable by the following formula (2) is from 10 to 20%, Crystallinity(%)=(S19+S20) / (S17+S19+S20)×100 Percentage of quasicrystalline layer (%) = S20 / (S17+S19+S20)×100 [4] Method for producing the film according to claim 1, characterized byThe process involves extruding a melt of an ethylene tetrafluoroethylene copolymer from an extrusion die in the form of a film, contacting the film with a first cooling device so that the surface temperature is higher than the crystallization temperature of the copolymer and lower than the melting point of the copolymer for a predetermined time, thus obtaining a primarily cooled product, then removing the primarily cooled product from the first cooling device and cooling it within a predetermined time from the time of removal by a second cooling device to a temperature of at least (melting point of the copolymer - 120 °C) and at most (melting point of the copolymer - 80 °C). [5] Method for producing a film according to claim 4, wherein the period of contact of the film with the first cooling device is from 3 to 20 seconds. [6] Method for producing a film according to claim 4 or 5, wherein the time for cooling to the aforementioned temperature by the second cooling device from the time of detachment from the first cooling device is within one second. [7] A method for producing a film according to any one of claims 4 to 6, wherein the ethylene-tetrafluoroethylene copolymer is a copolymer comprising tetrafluoroethylene units, ethylene units and third units based on a monomer other than tetrafluoroethylene and ethylene. [8] Method for producing a film according to any one of claims 4 to 7, wherein the cooling of the primarily cooled product is carried out by contact with a cooling roller, an air scraper or by immersion in water. [9] Method for producing the ethylene tetrafluoroethylene copolymer film according to any one of claims 1 to 3, characterized byExtruding a molten mixture of the following ETFE (A) and the following ETFE (B) in a mass ratio of 80 / 20 to 95 / 5 from an extrusion die in the form of a film, followed by cooling, ETFE (A): an ethylene-tetrafluoroethylene copolymer comprising tetrafluoroethylene units, ethylene units and third units based on a monomer other than tetrafluoroethylene and ethylene, wherein the molar ratio of the tetrafluoroethylene units to the ethylene units is from 45 / 55 to 65 / 35 and the proportion of the third units to the total of the tetrafluoroethylene units and the ethylene units is from 0.5 to 1.5 mol%, wherein the monomer other than tetrafluoroethylene and ethylene is a fluoroalkylethylene defined by the formula X(CF2) n CY=CH2 is represented, where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer from 2 to 8. ETFE (B): an ethylene-tetrafluoroethylene copolymer comprising tetrafluoroethylene units, ethylene units and third units based on a monomer other than tetrafluoroethylene and ethylene, wherein the molar ratio of the tetrafluoroethylene units to the ethylene units is from 45 / 55 to 65 / 35 and the proportion of the third units to the total of the tetrafluoroethylene units and the ethylene units is from 3.5 to 6 mol%, wherein the monomer other than tetrafluoroethylene and ethylene is a fluoroalkylethylene defined by the formula X(CF2) n CY=CH2 is represented, where X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer from 2 to 8. [10] Use of the film according to any one of claims 1 to 3 as a separating film for the manufacture of a semiconductor device.

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