JP2021120433A - Fluororesin sheet and method for producing the same - Google Patents

Abstract

To provide a fluororesin sheet having preferable transparency.SOLUTION: A method for producing a fluororesin sheet comprises subjecting a fluororesin sheet to UV ozone treatment.SELECTED DRAWING: None

Description

The present invention relates to a fluororesin sheet and a method for producing the same.

Fluororesin is used in a wide range of fields because it has excellent heat resistance, chemical resistance, water repellency, weather resistance, electrical insulation, etc., and is an electronic component equipped with an electronic element such as an LED (Light Emitting Diode). There is also an example used for sealing.

As a fluororesin used as a sealing material, Patent Document 1 discloses a fluoropolymer (THV) containing at least tetrafluoroethylene (TFE), hexafluoropropylene (HFP) and vinylidene fluoride (VdF). .. Specifically, a fluoropolymer (THV) is dissolved in a solvent to prepare a solution having a viscosity suitable for coating, and the solution is applied and dried to seal electronic components.

Japanese Unexamined Patent Publication No. 2009-51876

However, the method of applying a solution of a fluoropolymer and drying it is complicated. In addition, fluororesin often has low transparency, and improvement is required when transparency of LED encapsulant or the like is required. Therefore, an object of the present invention is to provide a fluororesin that can be easily used and has good transparency.

The fluororesin sheet of the present invention and the method for producing the same, which have been able to solve the above problems, have the following configurations.
[1] A method for producing a sheet in which a fluororesin sheet is treated with UV ozone.
[2] The production method according to [1], wherein the fluororesin sheet has a thickness of 0.01 to 2.0 mm.
[3] The production method according to [1] or [2], wherein the fluororesin sheet contains a crystalline fluororesin and substantially contains no volatile components.
[4] The production method according to [3], wherein the crystalline fluororesin is a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer.
[5] The production method according to any one of [1] to [4], wherein the UV ozone treatment is a treatment of irradiating ultraviolet rays having a peak wavelength of 200 nm or less in an oxygen-containing gas atmosphere.
[6] The production method according to [5], wherein the ultraviolet irradiation output × the ultraviolet irradiation time is 0.01 W · hour / cm ^{2 or more.}
[7] The production method according to [5] or [6], wherein the ultraviolet irradiation output × the ultraviolet irradiation time is 0.42 W · hour / cm ^{2 or less.}
[8] A fluororesin sheet having a transmittance of light having a wavelength of 260 nm of 70% or more and satisfying the following formula (1).
Abs _{B- Abs A} <0.180t (1)
(Wherein, t is fluororesin .abs _A indicating the thickness (mm) of the sheet represents the absorbance of the fluororesin sheet at a wavelength of 600 nm, Abs _B represents the absorbance of the fluororesin sheet at a wavelength of 260 nm.)
[9] The sheet according to [8], wherein the fluororesin sheet contains a crystalline fluororesin and substantially contains no volatile components.
[10] The sheet according to [9], wherein the crystalline fluororesin is a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer.
[11] The sheet according to any one of [8] to [10], which has a thickness of 0.01 to 2.0 mm.

According to the fluororesin sheet of the present invention, the transparency is good and it can be easily used for sealing and the like.

_{FIG. 1 is a graph showing the relationship between Abs B − Abs A} of the fluororesin sheet and the thickness of the sheet in Examples and Comparative Examples.

The method for producing a fluororesin sheet of the present invention is characterized by subjecting the fluororesin sheet to UV ozone treatment. Since the fluororesin sheet of the present invention has been enhanced in transparency by UV ozone treatment, it can be suitably used as a sealing material for sealing an electronic element such as a light emitting element (preferably an ultraviolet light emitting element). ..

[Fluororesin sheet]
The fluororesin sheet refers to a sheet formed by molding a fluororesin. In the present specification, the "fluororesin" means a polymer of an olefin containing fluorine or a modified product thereof, and the modified product has, for example, a polar group such as -OH or -COOH at the end of the main chain. Includes those to combine.

As the fluorine resin, a fluorine resin is preferable in view of durability without a polar group such as -SO ₃ H group in the side chain, for example, tetrafluoroethylene - perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene Crystalline fluororesins such as ethylene-hexafluoropropylene copolymer (FEP), chlorotrifluoroethylene polymer (PCTFE), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV); Teflon AF ™. Amorphous fluororesins such as Mitsui-Kemers Fluoroproducts) and Cytop (trademark; AGC) can be mentioned, and these fluororesins may be used alone or in combination of two or more. You may.

As the fluororesin, a crystalline fluororesin is more preferable, and a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV) is even more preferable. A fluororesin sheet formed from a crystalline fluororesin, particularly a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV resin), is used as a base material when used as a sealing material for electronic components as described later. It is preferable because it has excellent adhesion to fluoropolymers and electronic elements.

The THV resin includes a constituent unit T derived from tetrafluoroethylene, a constituent unit H derived from hexafluoropropylene, and a constituent unit V derived from vinylidene fluoride, and is the sum of the constituent unit T, the constituent unit H, and the constituent unit V. The molar ratio (T) of the constituent unit T to the total of the constituent unit T is 0.25 or more, and the molar ratio (V) of the constituent unit V to the total of the constituent unit T, the constituent unit H, and the constituent unit V is 0.60 or less. Is preferable. As a result, heat resistance and adhesion to a base material and an electronic element can be improved.

The molar ratio (T) of the structural unit T to the total of the structural unit T, the structural unit H, and the structural unit V is preferably 0.25 or more. This tends to improve the adhesion. Therefore, the lower limit of the molar ratio (T) of the constituent unit T is more preferably 0.28 or more, still more preferably 0.30 or more. On the other hand, the upper limit of the molar ratio (T) of the constituent unit T is preferably 0.75 or less, more preferably 0.60 or less, still more preferably 0.50 or less from the viewpoint of transparency.

The molar ratio (V) of the constituent unit V to the total of the constituent unit T, the constituent unit H, and the constituent unit V is preferably 0.60 or less. This tends to improve transparency and adhesion. Therefore, the upper limit of the molar ratio (V) of the constituent unit V is preferably 0.58 or less, more preferably 0.56 or less. On the other hand, the lower limit of the molar ratio (V) of the constituent unit V is preferably 0.20 or more. As a result, the refractive index of the resin can be increased, and the difference in the refractive index at the interface between the element and the resin can be alleviated, so that the efficiency of extracting light from the element is improved. Therefore, the lower limit of the molar ratio (V) of the constituent unit V is more preferably 0.30 or more, still more preferably 0.40 or more, and even more preferably 0.50 or more.

The molar ratio (H) of the structural unit H to the total of the structural unit T, the structural unit H, and the structural unit V is preferably 0.05 or more and 0.50 or less. The lower limit of the molar ratio (H) of the structural unit H is more preferably 0.07 or more, still more preferably 0.09 or more. On the other hand, the upper limit of the molar ratio (H) of the constituent unit H is more preferably 0.40 or less, still more preferably 0.30 or less, still more preferably 0.20 or less from the viewpoint of heat resistance.

The ratio of the molar ratio (V) to the molar ratio (T) (molar ratio (V) / molar ratio (T)) is preferably 0.20 or more and 3.50 or less. By controlling the molar ratio (V) / molar ratio (T) within the above range, the adhesion tends to be improved. In addition, it is possible to prevent the resin from being colored when heated at a high temperature. The lower limit of the molar ratio (V) / molar ratio (T) is more preferably 0.50 or more, still more preferably 1.00 or more, and even more preferably 1.30 or more. On the other hand, the upper limit of the molar ratio (V) / molar ratio (T) is more preferably 3.00 or less, still more preferably 2.50 or less, and even more preferably 2.00 or less.

The ratio of the molar ratio (H) to the molar ratio (T) (molar ratio (H) / molar ratio (T)) is preferably 0.10 or more and 0.80 or less. By controlling the molar ratio (H) / molar ratio (T) within the above range, transparency and adhesion tend to be improved. The lower limit of the molar ratio (H) / molar ratio (T) is more preferably 0.20 or more, still more preferably 0.24 or more, and even more preferably 0.28 or more. On the other hand, the upper limit of the molar ratio (H) / molar ratio (T) is more preferably 0.60 or less, still more preferably 0.50 or less, and even more preferably 0.40 or less.

The molar ratio of each constituent unit of the fluororesin can be determined by NMR measurement. In calculating the molar ratio, for example, Eric B. Twum et al., “Multidimensional 19F NMR Analyses of Terpolymers from Vinylidene Fluoride (VDF) -Hexafluoropropylene (HFP) -Tetrafluoroethylene (TFE)”, Macromolecules, 2015, Vol. 48, 11 No., p.3563-3576 can be referred to.

The THV resin may be a resin containing a constituent unit T, a constituent unit H, and other constituent units other than the constituent unit V. Examples of other structural units include ethylene-derived structural units, perfluoroalkyl vinyl ether-derived structural units, chlorotrifluoroethylene-derived structural units, and the like.

The total molar ratio of the structural unit T, the structural unit H, and the structural unit V to all the structural units of the THV resin is preferably 0.70 or more, more preferably 0.80 or more, still more preferably 0.90 or more, particularly. It is preferably 0.95 or more, and most preferably 1. That is, it is most preferably an unmodified THV resin. This makes it easier to improve the heat-resistant deformability.

In a preferred embodiment in which a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer or a modified product thereof (THV resin) is used as the fluororesin, the fluororesin is a fluororesin other than the THV resin (hereinafter referred to as fluororesin X). ) May be contained.

Examples of the fluororesin X include crystalline fluororesins, and specific examples thereof include tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and chlorotrifluoro. Examples thereof include an ethylene polymer (PCTFE). These fluororesins X may be used alone or in combination of two or more.

When the THV resin and the fluororesin X are used in combination, the amount of the fluororesin X with respect to 100 parts by mass of the THV resin is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 2 parts by mass or less, particularly preferably. Is 1 part by mass or less, most preferably 0 part by mass. That is, the fluororesin contained in the fluororesin sheet of the present invention is most preferably made of THV resin. As a result, the difference in refractive index between the resins is reduced, and the light extraction efficiency can be improved when used as a sealing material for electronic components. The light extraction efficiency is the efficiency at which the light generated by the light emitting element is extracted to the outside of the light emitting element.

The weight average molecular weight of the fluororesin is preferably 50,000 or more and 1,000,000 or less. By setting the weight average molecular weight to 50,000 or more, the viscosity at the time of melting can be increased, so that the shape change of the sealing resin at the time of lighting the LED can be suppressed. The lower limit of the weight average molecular weight of the fluororesin is more preferably 100,000 or more, still more preferably 200,000 or more, still more preferably 250,000 or more, and particularly preferably 300,000 or more. On the other hand, the meltability is improved by setting the weight average molecular weight of the fluororesin to 1,000,000 or less. The upper limit of the weight average molecular weight of the fluororesin is more preferably 800,000 or less, still more preferably 500,000 or less, still more preferably 450,000 or less, and particularly preferably 400,000 or less. The weight average molecular weight is a standard polystyrene conversion value.

When the fluororesin is a copolymer, the copolymer may be either a random copolymer or a block copolymer, but is preferably a random copolymer. In particular, by changing the THV resin to a random copolymer resin, the crystallinity of the constituent unit T and the constituent unit V can be suppressed, and transparency can be easily ensured.

The refractive index of the fluororesin sheet is preferably more than 1.34, more preferably 1.35 or more, still more preferably 1.36 or more. As a result, the difference in the refractive index between the light emitting element (preferably the ultraviolet light emitting element) and the sealing portion formed from the fluororesin sheet can be reduced, and the total reflection at the interface between the light emitting element and the sealing portion is reduced. Therefore, the light extraction efficiency can be improved. On the other hand, the upper limit of the refractive index of the fluororesin sheet may be, for example, 1.45 or less, preferably 1.40 or less. The refractive index may be a value described in a catalog value or a general physical property table, or can be measured by an Abbe refractive index meter, an ellipsometer, or the like.

The fluororesin sheet preferably has a glass transition point or a melting point of 90 ° C. or higher and 278 ° C. or lower. When the glass transition point or the melting point is 90 ° C. or higher, melting of the sealing member due to heat generation of the electronic element can be prevented. The glass transition point or the lower limit of the melting point of the fluororesin sheet is more preferably 100 ° C. or higher, still more preferably 110 ° C. or higher, and even more preferably 115 ° C. or higher. On the other hand, since the melting point of Au-Sn (20% by mass), which is a general solder material, is 278 ° C., the glass transition point or the melting point of the fluororesin sheet is 278 ° C. or lower, so that the fluororesin sheet is heated. The electronic element can be easily sealed by melting. Further, it is possible to prevent the bumps described later from melting when sealing by heating and melting. The upper limit of the glass transition point or melting point of the fluororesin sheet is more preferably 200 ° C. or lower, still more preferably 170 ° C. or lower, still more preferably 150 ° C. or lower, and particularly preferably 130 ° C. or lower. Here, in general, a fluororesin sheet containing a crystalline fluororesin exhibits a glass transition point and a melting point, but it is preferable that a larger value is in the above temperature range. The glass transition point or melting point of the fluororesin sheet is changed from −50 ° C. to 200 ° C. at a heating rate of 10 ° C./min using, for example, a differential scanning calorimeter (DSC, manufactured by Hitachi High-Tech Science Co., Ltd.). It can be obtained by measuring the intermediate glass temperature or the melting peak temperature (Tm) from the DSC curve (melting curve in the case of the melting point) obtained thereby. For example, 3M's "THV500GZ" has a melting point of about 165 ° C, 3M's "THV221AZ" has a melting point of about 115 ° C, and AGC's "Cytop" (trademark) has a glass transition point of 108 ° C. Degree. Further, the crystalline fluororesin preferably used in the present invention is solid at room temperature, has no tackiness on the surface after sealing, has sufficient hardness, and has appropriate fluidity by heating to a melting point or higher. Can be expressed, so that the electronic element can be sealed even if it is a single layer.

It is preferable that the fluororesin sheet contains substantially no volatile components. The volatile component contained in the fluororesin sheet is preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 1% by mass or less.

The content of volatile components can be measured by thermal analysis. The content of volatile components contained in the fluororesin sheet can be measured using a differential thermogravimetric simultaneous measuring device or the like, and the temperature of the fluororesin sheet is raised to the mass of the resin at 30 ° C. and 300. It can be obtained by measuring the mass of the resin at ° C. and dividing the mass difference between the mass of the resin at 30 ° C. and the resin at 300 ° C. by the mass of the resin at 30 ° C. Further, examples of the volatile component include water, a solvent, and the like. When it is desired to specify the volatile component, the volatile component may be analyzed by using a gas mass spectrometer in combination.

The fluororesin sheet may further contain a filler and other components, if necessary. When the fluororesin sheet contains a filler, thermal decomposition of the fluororesin sheet can be prevented. In the fluororesin sheet, the fluororesin is preferably a matrix component or a main component, and the content of the fluororesin in the fluororesin sheet is, for example, 40% by mass or more, preferably 50% by mass or more. It is preferably 60% by mass or more, more preferably 70% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.

Examples of the filler include inorganic fillers such as metal fluoride, metal oxide, metal phosphate, metal carbonate, metal sulfonate, metal nitrate, metal nitride, and boron nitride. The filler may be used alone or in combination of two or more. A preferred filler is metal fluoride. The metal fluoride has a small difference in refractive index from the fluororesin used in the present invention, and can improve the light extraction efficiency when sealing the light emitting element.

Examples of the metal fluoride include calcium fluoride, barium fluoride, strontium fluoride, lithium fluoride, magnesium fluoride, sodium fluoride, cryolite and the like, and magnesium fluoride is preferable. These metal fluorides may be used alone or in combination of two or more.

The particle size of the filler is preferably 300 μm or less. When the filler is 300 μm or less, discoloration due to an increase in temperature of the fluororesin sheet can be reduced. The particle size of the filler is more preferably 200 μm or less, still more preferably 100 μm or less, even more preferably 50 μm or less, particularly preferably 30 μm or less, and particularly preferably 20 μm or less. On the other hand, the particle size of the filler is preferably 0.5 μm or more. By setting the particle size of the filler to 0.5 μm or more, it is possible to suppress light scattering between the fluororesin and the filler, and the transparency of the fluororesin sheet is excellent. The lower limit of the particle size of the filler is more preferably 1 μm or more, still more preferably 5 μm or more. The particle size of this filler is a particle size D ₅₀ having a volume accumulation frequency of 50% by a laser diffraction method.

The difference in refractive index between the fluororesin and the filler is preferably 0.05 or less. By reducing the difference in refractive index in this way, it is possible to suppress light scattering on the surface of the filler (the interface between the surface of the filler and the fluororesin in the composition), so that the light extraction efficiency can be improved. can. The difference in refractive index between the fluororesin and the filler is more preferably 0.04 or less, still more preferably 0.03 or less. On the other hand, the lower limit of the difference in refractive index between the fluororesin and the filler is not particularly limited, but may be, for example, 0.001 or more. The refractive index of the filler may be a value described in a catalog value or a general physical property table, or may be measured by an Abbe refractive index meter, an ellipsometer, or the like.

It is preferable that the fluororesin sheet of the present invention contains substantially no filler. As a result, the transparency of the fluororesin sheet can be improved as compared with the case where the filler is contained. Here, the fact that the fluororesin sheet contains substantially no filler means that the concentration of the filler contained in the fluororesin sheet is 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less, and further preferably 0% by mass. Is.

As a method for molding the fluororesin into a sheet, various known molding methods can be adopted, and a molten resin such as a press molding method, an extrusion molding method, an injection molding method, a blow molding method, or a coating method can be used. A molding method using a molten resin can be adopted.

The thickness of the fluororesin sheet is preferably 0.01 mm or more, more preferably 0.05 mm or more, still more preferably 0.10 mm or more. The thickness of the fluororesin sheet is preferably 2.0 mm or less, more preferably 1.0 mm or less, still more preferably 0.8 mm or less, and particularly preferably 0.6 mm or less. By setting the thickness of the fluororesin sheet within the above range, discoloration of the sheet due to UV ozone treatment, which will be described later, can be prevented, and the mechanical strength and barrier properties of the resin after sealing can be increased.

[UV ozone treatment]
By applying the UV ozone treatment to the fluororesin sheet, the transparency of the fluororesin sheet is improved, probably because the factor for reducing the transparency existing in the fluororesin sheet is removed by the UV ozone treatment.

As the UV ozone treatment, it is preferable to irradiate ultraviolet rays having a peak wavelength at 200 nm or less (preferably 190 nm or less) in an oxygen-containing gas atmosphere, and the range is 150 nm or more and 200 nm or less, and 250 nm or more and 300 nm or less. It is more preferable to irradiate ultraviolet rays having peak wavelengths, respectively. Examples of the light source for irradiating the ultraviolet rays include a low-pressure mercury lamp.

The oxygen-containing gas is not particularly limited as long as it contains oxygen, and may be, for example, an oxygen gas, a mixed gas of an oxygen gas and an inert gas, or air. As the inert gas, nitrogen gas or argon gas can be used. When a mixed gas is used, the concentration of oxygen gas in the mixed gas is preferably adjusted in the range of 1% by volume or more and 30% by volume or less.

The UV ozone treatment may be performed under atmospheric pressure, pressurization, or reduced pressure, but it is preferably performed under atmospheric pressure.

The treatment time of the UV ozone treatment, that is, the irradiation time of the ultraviolet rays is preferably 1 minute or more, more preferably 10 minutes or more, further preferably 30 minutes or more, particularly preferably 1 hour or more, and most preferably 2 hours. That is all. By setting the treatment time within the above range, the transparency of the fluororesin sheet is further improved. From the viewpoint of productivity, the upper limit of the treatment time of the UV ozone treatment is preferably 10 hours or less, and may be 8 hours or less, or 5 hours or less.

The irradiation output of the ultraviolet rays × the irradiation time of the ultraviolet rays ^{is preferably 0.01 W · hour / cm 2} or more, more preferably 0.03 W · hour / cm ² or more, still more preferably 0.05 W · hour /. It is cm ² or more. By setting the value of the ultraviolet irradiation output × the ultraviolet irradiation time in the above range, the transparency of the fluororesin sheet is further improved. Further, if the value of the ultraviolet irradiation output × the ultraviolet irradiation time is too high, the fluidity of the fluororesin sheet deteriorates and melt sealing, which will be described later, becomes difficult. Therefore, the ultraviolet irradiation output × the ultraviolet rays. irradiation time is preferably not more than 0.42W · hour / cm ^2, more preferably 0.30W · hour / cm ^2, more preferably not more than 0.20W · hour / cm ^2.

The thickness, refractive index, melting point or glass transition point of the fluororesin sheet after UV ozone treatment, the composition of the fluororesin contained in the fluororesin sheet, etc. are the same as those of the fluororesin sheet before UV ozone treatment, but the fluororesin The weight average molecular weight of the fluororesin contained in the sheet tends to increase. The weight average molecular weight of the fluororesin after UV ozone treatment is preferably 50,000 or more, more preferably 100,000 or more, still more preferably 200,000 or more, still more preferably 250,000 or more, and particularly preferably. It is over 300,000. The upper limit of the weight average molecular weight of the fluororesin after UV ozone treatment is preferably 1,000,000 or less, more preferably 800,000 or less, still more preferably 600,000 or less, still more preferably 500. It is 000 or less, particularly preferably 450,000 or less. The weight average molecular weight is a standard polystyrene conversion value.

As will be described later, the fluororesin sheet of the present invention is suitably used as a sealing material for sealing an electronic component provided with a light emitting element (preferably an ultraviolet light emitting element). Since the emission peak wavelength of the ultraviolet light emitting element is preferably set appropriately in the range of 200 to 365 nm, the fluororesin sheet used for the encapsulant has high light transmittance in the above range wavelength and the above range. It is required that the absorption of light at the wavelength is small. Since the fluororesin sheet of the present invention has its transparency enhanced by UV ozone treatment, the transmittance of light having a wavelength of 260 nm is 70% or more, and the following formula (1) is satisfied.
Abs _{B- Abs A} <0.180t (1)
(Wherein, t is fluororesin .abs _A indicating the thickness (mm) of the sheet represents the absorbance of the fluororesin sheet at a wavelength of 600 nm, Abs _B represents the absorbance of the fluororesin sheet at a wavelength of 260 nm.)

The absorbances Abs _B and Abs _A of the fluororesin sheet can be calculated based on the following formula (2).
Absorbance = -log ₁₀ (T / 100) (2)
(In the formula, T indicates the total light transmittance.)

As shown in the formula (2) _{, both Abs B} and Abs _A are absorbances obtained from the total light transmittance T, and both include the absorbance of the reflected component. By calculating the difference between Abs _{B- Abs A} , the effect of absorption of the reflected component can be canceled, and when requirements other than thickness (such as the degree of UV ozone treatment) are equal, the difference (Abs _{B- Abs A} ) and the sheet The thickness t is logically related to a straight line passing through the origin. The small slope of this straight line means that the transparency effect of the UV ozone treatment is exhibited, and the slope of the fluororesin sheet of the present invention is smaller than 0.180.

From the viewpoint of transparency, Abs _{B − Abs A} is preferably less than 0.176t, more preferably less than 0.170t. The lower limit of Abs _{B − Abs A} is not particularly limited, but may be 0.10 tons or more, or 0.13 tons or more. _{In other words, the value of Abs B- Abs A} ((Abs _{B- Abs A} ) / t) with respect to the sheet thickness t is less than 0.180, preferably less than 0.176, and more preferably less than 0.170. Also, it may be 0.10 or more, or 0.13 or more.

The transmittance of light having a wavelength of 260 nm is preferably 73% or more, more preferably 75% or more, and particularly preferably 78% or more.

[Encapsulant]
As described above, since the fluororesin sheet of the present invention has improved transparency, it can be suitably used as a sealing material for sealing an electronic element such as a light emitting element (preferably an ultraviolet light emitting element).

The electronic element is usually attached to a wiring base material. The wiring base material is a base material having electrode wiring formed on the surface thereof, and is sometimes referred to as a package. The wiring base material may be either a surface mount type or a chip-on-board type in which a plurality of electronic elements are surface-mounted. Further, there may be a connected wiring base material for manufacturing a plurality of surface mount type electronic components by dividing the components. Further, the shape of the wiring base material used for the surface mount type, the connection type, the chip-on-board type and the like may be a cavity type or a flat plate type. Further, in the surface mount type, the connection type, and the chip-on-board type, the electronic element may be directly installed on the wiring base material via a bump, or the electronic element may be mounted on a submount via a bump. The electronic element component may be used as an electronic element component, and the electronic element component may be installed on a wiring base material.

The sealing with the fluororesin sheet of the present invention is, for example, a method in which the fluororesin sheet is laminated on the electronic element mounting side of the wiring base material, and then the fluororesin sheet is heated to a melting point or a glass transition point or higher to be melted and cooled. It can be carried out by (hereinafter, referred to as a melt sealing method). The melt sealing method is preferable because the work is simpler than the coating method in which an electronic device or the like is sealed by applying a solution in which a polymer is dissolved and drying it. Further, when the upper surface of the sealing portion is formed to have a convexly raised shape as described later, the melt sealing method is preferable.

The heating temperature of the fluororesin sheet is such that when the fluororesin sheet is substantially composed of crystalline fluororesin (for example, 80% or more, preferably 90% or more, more preferably 95% or more on a mass basis), the fluororesin It is preferably equal to or higher than the melting point of the sheet, more preferably + 10 ° C. or higher, and further preferably + 20 ° C. or higher. Further, when the fluororesin sheet is a fluororesin sheet substantially (for example, 80% or more, preferably 90% or more, more preferably 95% or more) made of an amorphous resin (on a mass basis, for example, 80% or more, more preferably 95% or more), the fluororesin sheet The heating temperature is preferably equal to or higher than the glass transition point, more preferably + 10 ° C or higher, and further preferably + 20 ° C or higher. The upper limit of the heating temperature is, for example, 278 ° C. or lower, more preferably 250 ° C. or lower, still more preferably 200 ° C. or lower, and particularly preferably 150 ° C. or lower.

The heating time of the fluororesin sheet is preferably 10 minutes or more and 20 hours or less, and more preferably 30 minutes or more and 10 hours or less.

In an electronic component having an ultraviolet light emitting element, as long as the fluororesin seals the ultraviolet light emitting element, the sealing portion can take various shapes, for example, a lens shape, a plate shape, a truncated cone shape, and a columnar shape. , Hemispherical, semi-elliptical spherical and the like. It is preferable to use the ultraviolet light emitting element as a condensing lens with the upper surface of the ultraviolet light emitting element as a lens (the upper surface of the ultraviolet light emitting element is a convex curved surface).

When the sealing resin on the upper surface of the ultraviolet light emitting element has a lens shape, it is preferable to lengthen the heating time of the fluororesin sheet at the time of sealing. By continuing to heat the fluororesin sheet, the fluororesin sheet rises like a lens on the upper surface of the ultraviolet light emitting element.

Further, the sealing portion formed by the fluororesin sheet of the present invention may be further subjected to UV ozone treatment. By applying UV ozone treatment to the sealing portion, the transparency of the sealing portion can be further enhanced. The conditions for UV ozone treatment on the sealing portion may be the same as the conditions for UV ozone treatment on the fluororesin sheet.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the following examples as well as the present invention, and appropriate modifications are made to the extent that it can be adapted to the purpose of the preceding and following descriptions. Of course, it is possible to carry out, and all of them are included in the technical scope of the present invention.

[Measurement of sheet thickness]
The thickness of the sample (sheet) was measured using a Digimicro (manufactured by Nikon Corporation, apparatus: MF-501 + counter MFC-101A + MS-11C, stylus: flat stylus).

[Measurement method of total light transmittance and absorbance]
The total light transmittance and absorbance of the sample (sheet) were measured based on the following conditions.
Measurement condition device: Ultraviolet visible near infrared spectrophotometer UV-3600 (manufactured by Shimadzu Corporation)
Attachment: Integrating sphere ISR-3100
Background measurement: Atmosphere

[Measurement of light intensity of low-pressure mercury lamp]
The light intensity of the low pressure mercury lamp was measured based on the following conditions. As a result of the measurement, the light intensity (output) of the low-pressure mercury lamp used in this example was 1.38 W / (2.5 × 2.5 × 3.14) = 0.070 W / cm ² .
Measurement condition device: VEGA laser power / energy meter (manufactured by OPHIR)
Measurement wavelength range: UV
Measurement timing: Value 5 minutes after the start of lighting Measurement time Average: 10 seconds Measurement position: Installed so that the top surface of the detector comes at a distance of 5 cm from the low-pressure mercury lamp Detector size: 5 cmφ

[Manufacturing method of THV film]
To 80 parts by mass of N, N-dimethylacetamide (purity 98%) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 20 parts by mass of THV221AZ manufactured by 3M Co., Ltd. was added, and the mixture was stirred and mixed overnight at room temperature. Put 3.0 g to 8.0 g of the obtained mixture on a PFA Petri dish (inner diameter x outer diameter x height = φ50 mm x φ55 mm x 14.5 mm) and heat-treat at 200 ° C. for 10 hours using a blower dryer. Then, a cured product of Samples 1 to 5 was obtained. The sheet thickness (t) of each sample is shown in Table 1.

[Comparative Example 1]
The sheet of untreated sample 1 was designated as Comparative Example 1. The total light transmittance of Sample 1 at wavelengths of 260 nm and 600 nm was measured, and the absorbance Abs _{B at a wavelength of 260 nm and the absorbance Abs A} at a wavelength of 600 nm were calculated. The total light transmittance T _B of the sheet at a wavelength of 260nm is shown in Table 1, it was greater than 70%. However, as shown in FIG. 1 and Table 1, the sheet of Comparative Example 1 did not satisfy the formula (1).

[Example 1]
Sample 1 was irradiated with a low-pressure mercury lamp (manufactured by Sen Special Light Source Co., Ltd., PL16-110D) for 1 hour and treated with UV ozone. Aluminum foil was laid on the upper surface of the jack, sample 1 was placed on it, and the height was adjusted with the jack so that the distance between the upper surface of the sample and the mercury lamp was 5 cm. The total light transmittance T _B in the sheet of wavelength 260nm of after 1 hour UV-ozone treatment is shown in Table 1, was greater than 70%. Further, as shown in FIGS. 1 and 1, the sheet of Example 1 satisfied the formula (1).

[Example 2]
The sheet obtained in Example 1 was further irradiated with a low-pressure mercury lamp for 1 hour, and UV ozone treatment was performed for a total of 2 hours. The total light transmittance T _B in the sheet of wavelength 260nm of after 2 hours to UV ozone treatment is shown in Table 1, it was greater than 70%. Further, as shown in FIGS. 1 and 1, the sheet of Example 2 satisfied the formula (1).

[Comparative Example 2]
The sheet of the untreated sample 2 was designated as Comparative Example 2. The total light transmittance at a wavelength 260nm sample 2 T _B are shown in Table 1, it was greater than 70%. However, as shown in FIGS. 1 and 1, the sheet of Comparative Example 2 did not satisfy the formula (1).

[Example 3]
Sheets were obtained in the same manner as in Example 1 except that sample 2 was used instead of sample 1. The total light transmittance T _B in the sheet of wavelength 260nm of after 1 hour UV-ozone treatment is shown in Table 1, was greater than 70%. Further, as shown in FIGS. 1 and 1, the sheet of Example 3 satisfied the formula (1).

[Example 4]
The sheet obtained in Example 3 was further irradiated with a low-pressure mercury lamp for 1 hour, and UV ozone treatment was performed for a total of 2 hours. The total light transmittance T _B in the sheet of wavelength 260nm of after 2 hours to UV ozone treatment is shown in Table 1, it was greater than 70%. Further, as shown in FIGS. 1 and 1, the sheet of Example 4 satisfied the formula (1).

[Comparative Example 3]
The sheet of the untreated sample 3 was designated as Comparative Example 3. The total light transmittance T _B at the wavelength 260nm sample 3 are shown in Table 1, it was greater than 70%. However, as shown in FIGS. 1 and 1, the sheet of Comparative Example 3 did not satisfy the formula (1).

[Example 5]
Sheets were obtained in the same manner as in Example 1 except that sample 3 was used instead of sample 1. The total light transmittance T _B in the sheet of wavelength 260nm of after 1 hour UV-ozone treatment is shown in Table 1, was greater than 70%. Further, as shown in FIGS. 1 and 1, the sheet of Example 5 satisfied the formula (1).

[Example 6]
The sheet obtained in Example 5 was further irradiated with a low-pressure mercury lamp for 1 hour, and UV ozone treatment was performed for a total of 2 hours. The total light transmittance T _B in the sheet of wavelength 260nm of after 2 hours to UV ozone treatment is shown in Table 1, it was greater than 70%. Further, as shown in FIGS. 1 and 1, the sheet of Example 6 satisfied the formula (1).

[Comparative Example 4]
The sheet of the untreated sample 4 was designated as Comparative Example 4. The total light transmittance T _B at the wavelength 260nm sample 4 are shown in Table 1, it was greater than 70%. However, as shown in FIGS. 1 and 1, the sheet of Comparative Example 4 did not satisfy the formula (1).

[Example 7]
Sheets were obtained in the same manner as in Example 1 except that sample 4 was used instead of sample 1. The total light transmittance T _B in the sheet of wavelength 260nm of after 1 hour UV-ozone treatment is shown in Table 1, was greater than 70%. Further, as shown in FIGS. 1 and 1, the sheet of Example 7 satisfied the formula (1).

[Example 8]
The sheet obtained in Example 7 was further irradiated with a low-pressure mercury lamp for 1 hour, and UV ozone treatment was performed for a total of 2 hours. The total light transmittance T _B in the sheet of wavelength 260nm of after 2 hours to UV ozone treatment is shown in Table 1, it was greater than 70%. Further, as shown in FIGS. 1 and 1, the sheet of Example 8 satisfied the formula (1).

[Comparative Example 5]
The sheet of the untreated sample 5 was designated as Comparative Example 5. The total light transmittance T _B at the wavelength 260nm sample 5 are shown in Table 1, it was greater than 70%. However, as shown in FIGS. 1 and 1, the sheet of Comparative Example 5 did not satisfy the formula (1).

[Example 9]
Sheets were obtained in the same manner as in Example 1 except that sample 5 was used instead of sample 1. The total light transmittance T _B in the sheet of wavelength 260nm of after 1 hour UV-ozone treatment is shown in Table 1, was greater than 70%. Further, as shown in FIGS. 1 and 1, the sheet of Example 9 satisfied the formula (1).

[Example 10]
The sheet obtained in Example 9 was further irradiated with a low-pressure mercury lamp for 1 hour, and UV ozone treatment was performed for a total of 2 hours. The total light transmittance T _B in the sheet of wavelength 260nm of after 2 hours to UV ozone treatment is shown in Table 1, it was greater than 70%. Further, as shown in FIGS. 1 and 1, the sheet of Example 10 satisfied the formula (1).

Since the fluororesin sheet of the present invention has excellent transparency, an electron provided with an ultraviolet light emitting element such as an analyzer, a photocatalyst device, a phototherapy device, a bill appraisal device, an air / water sterilization purification device, and a UV resin curing device. It can be used as a sealing material for parts.

Claims (11)

A method for manufacturing a sheet in which a fluororesin sheet is treated with UV ozone. The manufacturing method according to claim 1, wherein the fluororesin sheet has a thickness of 0.01 to 2.0 mm. The production method according to claim 1 or 2, wherein the fluororesin sheet contains a crystalline fluororesin and substantially does not contain a volatile component. The production method according to claim 3, wherein the crystalline fluororesin is a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer. The production method according to any one of claims 1 to 4, wherein the UV ozone treatment is a treatment of irradiating ultraviolet rays having a peak wavelength of 200 nm or less in an oxygen-containing gas atmosphere. The manufacturing method according to claim 5, wherein the ultraviolet irradiation output × the ultraviolet irradiation time is 0.01 W · hour / cm ^{2 or more.} The production method according to claim 5 or 6, wherein the ultraviolet irradiation output × the ultraviolet irradiation time is 0.42 W · hour / cm ^{2 or less.} A fluororesin sheet having a transmittance of light having a wavelength of 260 nm of 70% or more and satisfying the following formula (1).
Abs _{B- Abs A} <0.180t (1)
(Wherein, t is fluororesin .abs _A indicating the thickness (mm) of the sheet represents the absorbance of the fluororesin sheet at a wavelength of 600 nm, Abs _B represents the absorbance of the fluororesin sheet at a wavelength of 260 nm.) The sheet according to claim 8, wherein the fluororesin sheet contains a crystalline fluororesin and substantially does not contain a volatile component. The sheet according to claim 9, wherein the crystalline fluororesin is a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer. The sheet according to any one of claims 8 to 10, which has a thickness of 0.01 to 2.0 mm.

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