JP2020191440A - Electronic component and manufacturing method - Google Patents

Abstract

To provide a manufacturing method of an electronic component having good heat-resistant deformation of a fluororesin sealing member.SOLUTION: A manufacturing method of an electronic component includes the steps of covering an electronic element 2 attached to a wiring substrate with fluororesin, and irradiating the fluororesin covering the electronic element with radiation. The fluororesin is preferably a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer. The radiation is preferably an electron beam. An accelerating voltage of an electron beam is preferably 50 kV or more. The irradiation energy of the electron beam is preferably 20 kGy or more in terms of absorbed dose.SELECTED DRAWING: Figure 3

Description

The present invention relates to electronic components and methods for manufacturing them.

In electronic components equipped with electronic elements such as LEDs (Light Emitting Diodes), the electronic elements are often sealed with epoxy resin or silicone resin in order to prevent deterioration of the electronic elements, and there are cases where they are sealed with fluororesin. ..

For example, in Non-Patent Document 1, a perfluoro (4-vinyloxy-1-butene) (BVE) polymer having a CF ₃ terminal is used for encapsulating a deep ultraviolet AlGaN LED because it has excellent durability against deep ultraviolet rays. It is stated that it can be done. Further, Patent Document 1 discloses an ultraviolet light emitting device in which an ultraviolet light emitting element is sealed with an amorphous fluororesin. Patent Document 2 discloses that a fluoropolymer (THV) containing at least tetrafluoroethylene (TFE), hexafluoropropylene (HFP) and vinylidene fluoride (VdF) is used for encapsulating an LED element.

International Publication No. 2014/178288 Japanese Unexamined Patent Publication No. 2009-51876

Shoko Nagai et al., “Development of highly durable deep-ultraviolet AlGaN-based LED multichip array with hemispherical encapsulated structures using a selected resin through a detailed feasibility study”, Japanese Journal of Applied Physics, 2016, Vol. 55, 082101

By the way, an electronic element may generate heat depending on its type and usage state, and an LED element that emits deep ultraviolet rays is known as an example. On the other hand, the fluororesin used in the sealant is generally a thermoplastic resin, and may be deformed by the heat generated from the element. Therefore, an object of the present invention is to provide an electronic component having good heat-resistant deformation of the fluororesin sealing member.

The electronic component of the present invention and the manufacturing method thereof, which have been able to solve the above problems, have the following configurations.
[1] A process of covering an electronic element attached to a wiring substrate with a fluororesin,
A method for manufacturing an electronic component, which comprises a step of irradiating the fluororesin covering the electronic element with radiation.
[2] The production method according to [1], wherein the fluororesin is a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer.
[3] The production method according to [1] or [2], wherein the radiation is an electron beam.
[4] The manufacturing method according to [3], wherein the accelerating voltage of the electron beam is 50 kV or more.
[5] The production method according to [3] or [4], wherein the irradiation energy of the electron beam is 20 kGy or more in absorbed dose.
[6] An electronic component having a wiring base material and a fluororesin filled in the wiring base material as a sealing portion.
When the electronic component is held at a temperature of 150 ° C. for 60 hours with the interface between the filled fluororesin and air facing down, the average deformation rate V calculated by the following formula (1) is less than 1.30. Electronic components that are.
Average deformation rate V = ( _RS × R _d ) ^1/2 (1)
(In the formula, _RS is the standardized area of the fluororesin protruding from the wiring base material per unit frontal projected area of the sealing portion, and the _RS is the said after holding with respect to the standardized area before holding. Represents the ratio of standardized area, and R _d is the retention with respect to the standardized height before holding when the height of the fluororesin protruding from the wiring base material per unit front projected area of the sealing portion is defined as the normalized height. It represents the later ratio of the standardized height. The electronic element mounting surface or the electronic element mounting planned surface of the electronic component is referred to as the front surface of the electronic component, and the surface orthogonal to the electronic element mounting surface or the electronic element mounting planned surface is the side surface. )
[7] The electronic component according to [6], wherein the fluororesin is a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer.

According to the present invention, it is possible to provide an electronic component having good heat-resistant deformability of the fluororesin sealing member.

FIG. 1 is a schematic cross-sectional view showing an example of a conventional electronic device. FIG. 2 is a schematic cross-sectional view showing an example of a wiring base material on which a conventional electronic element is mounted. FIG. 3 is a schematic cross-sectional view showing an example of the electronic component of the present invention. FIG. 4 is a schematic cross-sectional view showing another example of the electronic component of the present invention. FIG. 5 is a schematic cross-sectional view showing another example of the electronic component of the present invention. FIG. 6 is a schematic cross-sectional view showing another example of the electronic component of the present invention. FIG. 7 is a schematic view showing an example of a conventional wiring base material. FIG. 8 is a schematic view for explaining a test situation of the electronic component of the present invention. FIG. 9 is another schematic view for explaining the test status of the electronic component of the present invention.

The present invention relates to a method for manufacturing an electronic component, which comprises a step of covering an electronic element attached to a wiring base material with a fluororesin and a step of irradiating the fluororesin covering the electronic element with radiation.
(1) Electronic Element The electronic element is generally a semiconductor, and examples thereof include a transistor and a diode, and a semiconductor diode is preferable. As the semiconductor diode, a light emitting diode is preferable, and an ultraviolet light emitting diode (hereinafter, may be referred to as an ultraviolet light emitting element) is particularly preferable. When the ultraviolet light emitting diode is sealed with an epoxy resin or a silicone resin, the deterioration of the resin is increased by ultraviolet rays, whereas when it is sealed with a fluororesin, the deterioration of the resin can be suppressed. Further, the ultraviolet light emitting diode generates a large amount of heat and may cause thermal deformation of the sealing portion. However, according to the present invention, the heat resistant deformation of the sealing portion can be improved.

FIG. 1 is a schematic cross-sectional view showing an example of the ultraviolet light emitting element. The ultraviolet light emitting element 2 as an electronic element is a flip-chip type element, has a p electrode 10 on the anode side on a part of the lower side surface, and a p layer 12 is formed on the p electrode 10. Further, another part of the lower side surface of the ultraviolet light emitting element 2 is provided with an n electrode 11 on the cathode side, and an n layer 14 is formed on the n electrode 11. The n-electrode 11 and the n-layer 14 are formed by shifting upward from the p-electrode 10 and the p-layer 12, and are active between the n-layer 14 existing above and the p-layer 12 existing below. Layer 13 is formed. In addition, the element substrate 15 exists above the n layer 14 existing above.

Examples of the n-layer 14 in the ultraviolet light emitting device 2 include a Si-containing AlGaN layer. Examples of the p-layer 12 include a Mg-containing GaN layer. The p-layer 12 may have a laminated structure with an electron block layer or the like, if necessary. Examples of the active layer 13 include an AlGaN layer.

By passing a forward current from the p electrode 10 and the p layer 12 toward the n layer 14 and the n electrode 11, light emission corresponding to the bandgap energy in the active layer 13 is generated. The bandgap energy can be controlled within the range of the bandgap energy (about 3.4 eV and about 6.2 eV) that GaN and AlN can take by adjusting, for example, the AlN mole fraction of the active layer 13. Ultraviolet light emission having an emission wavelength of about 200 nm to about 365 nm can be obtained.

A sapphire substrate, an aluminum nitride substrate, or the like can be used as the element substrate 15. Ni / Au can be used as the material of the p electrode 10, Ti / Al / Ti / Au and the like can be used as the material of the n electrode 11. Further, the exposed surface between the p electrode 10 and the n electrode 11 may be covered with a protective insulating film (not shown) such as SiO ₂ in order to prevent a short circuit.

The emission peak wavelength of the ultraviolet light emitting element 2 can be appropriately set in the range of 200 to 365 nm, and is preferably 300 nm or less. Since the sterilization effect is easily exhibited when the emission peak wavelength is 300 nm or less, the ultraviolet light emitting element 2 can be used as a light emitting device for sterilization. The emission peak wavelength is more preferably 280 nm or less.

(2) Wiring base material The wiring base material is a base material having electrode wiring formed on its surface, 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, and it is preferable that bumps are formed on the surface on which the electronic element is mounted. Ceramics such as aluminum nitride (AlN) and alumina (Al ₂ O ₃ ) can be used as the base material of the wiring base material.

FIG. 2 is a schematic cross-sectional view showing a state in which the ultraviolet light emitting element of FIG. 1 is mounted on a surface mount type wiring base material. In the ultraviolet light emitting element mounting wiring base material 6 of FIG. 2, the p electrode 10 and the n electrode 11 of the ultraviolet light emitting element 2 can be electrically connected to a wiring (not shown) on the base material 4 via a metal bump 5, respectively. It is fixed as. As described above, a chip-on-board type wiring base material can also be used in the present invention, and the present invention is not limited to the illustrated examples.

(3) Fluororesin In the present invention, as described above, the electronic element is sealed by covering the electronic element attached to the wiring base material with the fluororesin. As used herein, the term "fluororesin" means a polymer of an olefin containing fluorine or a modified product thereof, and a polar group such as -OH or -COOH is bonded to the modified product, for example, at the end of the main chain. Things are included. As the fluorine resin, fluorine resin having no polar group such as -SO ₃ H group in the side chain are preferable from the viewpoint of maintaining the performance of electronic components, for example, tetrafluoroethylene - perfluoroalkyl vinyl ether copolymer (PFA) , Tetrafluoroethylene-hexafluoropropylene copolymer (FEP), chlorotrifluoroethylene polymer (PCTFE), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV) and other crystalline fluororesins; Examples include amorphous fluororesins such as AF (trademark; manufactured by Mitsui-Kemers Fluoroproducts) and Cytop (trademark; manufactured by AGC). These fluororesins may be used alone or in combination of two types. The above may be used together. As the fluororesin, a crystalline fluororesin is more preferable, and a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV) is even more preferable. Crystalline fluororesins, particularly tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymers (THV resins), have excellent adhesion to substrates and electronic devices.

The THV resin includes a structural unit T derived from tetrafluoroethylene, a structural unit H derived from hexafluoropropylene, and a structural unit V derived from vinylidene fluoride, and is the sum of the structural unit T, the structural unit H, and the structural unit V. The molar ratio (T) of the structural unit T to the component T is 0.25 or more, and the molar ratio (V) of the structural unit V to the total of the structural unit T, the structural unit H, and the structural unit V is 0.60 or less. Is preferable. This makes it possible to improve the heat resistance of the ultraviolet light emitting element to heat generation and the adhesion of the ultraviolet light emitting device to the base material and the like.

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 structural 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 structural unit V to the total of the structural unit T, the structural unit H, and the structural unit V is preferably 0.60 or less. This tends to improve the 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 solubility in an organic solvent is improved, so that the number of times the resin composition is applied can be reduced when sealing the ultraviolet light emitting element. Therefore, the lower limit of the molar ratio (V) of the structural 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, from the viewpoint of solubility. On the other hand, the upper limit of the molar ratio (H) of the constituent unit B 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, coloring of the resin during high-temperature heating can be prevented. 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, the adhesion tends 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 structural unit of the fluororesin can be determined by the NMR measurement described in Examples described later. 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 structural unit T, a structural unit H, and other structural units other than the structural unit V. Examples of other structural units include ethylene-derived structural units, perfluoroalkyl vinyl ether-derived structural units, and chlorotrifluoroethylene-derived structural units.

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.

The weight average molecular weight of the fluororesin (preferably the THV resin) 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 (preferably the THV resin) 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. Is. On the other hand, the solubility is improved by setting the weight average molecular weight of the fluororesin (preferably the THV resin) to 1,000,000 or less. The upper limit of the weight average molecular weight of the fluororesin (preferably the THV resin) is more preferably 800,000 or less, still more preferably 500,000 or less, even more preferably 450,000 or less, and particularly preferably 400,000 or less. Is. 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 a random copolymer is preferable. In particular, by changing the THV resin to a random copolymer resin, the crystallinity of the structural unit T and the structural unit V can be suppressed, and transparency can be easily ensured.

The refractive index of the fluororesin 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 an ultraviolet light emitting element) described later and the sealing portion can be reduced, the total reflection at the interface between the light emitting element and the sealing portion is reduced, and the light extraction efficiency is reduced. Can be improved. 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. On the other hand, the upper limit of the refractive index of the fluororesin 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 preferably has a melting point of 90 ° C. or higher and 278 ° C. or lower. When 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 lower limit of the melting point of the fluororesin 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 melting point of the resin is 278 ° C. or less, so that the electronic element is sealed by heating and melting the fluororesin. Can be easily done. Further, it is possible to prevent the bumps described later from melting when sealing by heating and melting. The upper limit of the melting point of the fluororesin 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. The melting point of the fluororesin of the present invention 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 melting peak temperature (Tm) from the obtained melting curve.

The fluororesin may be a resin composition containing a filler and other components, if necessary. When the fluororesin composition contains a filler, thermal decomposition of the fluororesin can be prevented. In the resin composition, the fluororesin is preferably a matrix component or a main component, and the content of the fluororesin in the resin composition is, for example, 40% by mass or more, preferably 50% by mass or more, more preferably. Is 60% by mass or more, more preferably 70% 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, 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, glacial stone 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 inorganic filler is preferably 300 μm or less. When the inorganic filler is 300 μm or less, discoloration due to an increase in the temperature of the fluororesin can be reduced. The particle size of the inorganic 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 inorganic filler is preferably 0.5 μm or more. By setting the particle size of the inorganic filler to 0.5 μm or more, it is possible to suppress light scattering between the resin and the filler, and the transparency of the resin is excellent. The lower limit of the particle size of the inorganic filler is more preferably 1 μm or more, still more preferably 5 μm or more. The particle size of the inorganic 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 of the present invention and the inorganic 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 inorganic filler (the interface between the surface of the inorganic filler and the fluororesin in the composition), thereby improving the light extraction efficiency. be able to. The difference in refractive index between the fluororesin of the present invention and the inorganic 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 of the present invention and the inorganic filler is not particularly limited, but may be, for example, 0.001 or more. The refractive index of the inorganic filler of the present invention 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.

When the fluororesin contains a filler, the amount of the filler with respect to 100 parts by mass of the total of the fluororesin and the filler is preferably 1 part by mass or more and 60 parts by mass or less. When the amount of the filler is 1 part by mass or more, it is possible to easily prevent thermal decomposition of the fluororesin. The lower limit of the amount of filler is more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more. On the other hand, when the amount of the filler is 60 parts by mass or less, the adhesion of the fluororesin is easily exhibited. The upper limit of the amount of the filler is more preferably 50 parts by mass or less, still more preferably 45 parts by mass or less.

The fluororesin composition containing the filler can be prepared by mixing the fluororesin and the inorganic filler. Examples of the preparation method include a method of mixing and cooling a molten fluororesin and a filler, a method of mixing with an inorganic filler in the presence of a solvent that dissolves or disperses the fluororesin, and a method of mixing in the presence of the solvent. There is a method of removing the solvent by filtration, concentration, or the like.

Examples of the solvent include ester solvents such as ethyl acetate, methyl acetate, propyl acetate, butyl acetate, ethyl propionate, and glycol esters obtained by adding an acetate group to glycol ether; acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclohexanone and the like. Ketone-based solvent; ether-based solvent such as diethyl ether, dipropyl ether, butyl ether, glycol ether, terrorahydrofuran; amide-based solvent such as N, N-dimethylformamide, N, N-dibutylformamide, N, N-dimethylacetamide Solvents; lactam solvents such as N-methyl-2-pyrrolidone; and the like. Of these, ester-based solvents, ketone-based solvents, and ether-based solvents are preferable, and ester-based solvents are more preferable. These organic solvents may be used alone or in combination of two or more.

When a solvent is used for mixing, the amount of the solvent with respect to 100 parts by mass of the fluororesin is preferably 100 parts by mass or more and 5000 parts by mass or less. When the amount is 100 parts by mass or more, the fluororesin of the present invention can be easily dissolved or dispersed. The amount of the solvent is more preferably 200 parts by mass or more, further preferably 400 parts by mass or more, and even more preferably 600 parts by mass or more. On the other hand, when the amount is 5000 parts by mass or less, the number of times of coating for sealing the ultraviolet light emitting device can be reduced. The amount of the solvent is more preferably 2000 parts by mass or less, further preferably 1200 parts by mass or less, and even more preferably 1000 parts by mass or less.

When the solvent is removed after mixing, the residual amount of the solvent after removal is preferably 200 parts by mass or less, more preferably 100 parts by mass or less, still more preferably 50 parts by mass or less, based on 100 parts by mass of the fluororesin. Even more preferably, it is 20 parts by mass or less.

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 composition is a fluororesin other than the THV resin (hereinafter referred to as fluororesin X). In some cases) may be contained.

Examples of the fluororesin X include crystalline fluororesins, and specifically, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and chlorotrifluoro. Examples thereof include ethylene (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 THV 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, and particularly preferably 1. It is less than or equal to parts by mass, most preferably 0 parts by mass. That is, the fluororesin contained in the resin composition of the present invention is most preferably made of THV resin. As a result, the difference in refractive index between the resins can be reduced and the light extraction efficiency can be improved.

The total content of the fluororesin and the inorganic filler with respect to the total mass of the resin composition (solid content) is preferably 90% by mass or more, more preferably 95% by mass or more, and preferably 97% by mass or more. Even more preferably, it is 99% by mass or more. As a result, the adhesiveness of the fluororesin and the thermal conductivity of the inorganic filler are easily exhibited, and the heat-resistant deformation property of the fluororesin member is improved.

(4) Sealing Sealing with a fluororesin is not particularly limited as long as the electronic element can be fixed, but when the electronic element is a light emitting element, it is preferable that the active layer can be shielded from external oxygen and moisture, and the entire light emitting element. Is more preferable to be able to block from external oxygen and moisture. 3, FIG. 4, FIG. 5, and FIG. 6 are schematic cross-sectional views showing an example in which the ultraviolet light emitting element mounting wiring base material 6 of FIG. 2 is sealed to form an electronic component.

The electronic component 1a of FIG. 3 is coated with a fluororesin from the lower surface (electrodes 10 and 11) to the upper surface (up to the element substrate 15) of the ultraviolet light emitting element 2 of the ultraviolet light emitting element mounting wiring base material 6 shown in FIG. It can be formed by forming the sealing portion 3a. An electronic component having an ultraviolet light emitting element can take various shapes as long as the fluororesin seals the ultraviolet light emitting element 2. For example, the upper surface thereof is used as a condensing lens as a convex curved surface. Is preferable. The electronic component 1b of FIG. 4 is an example in which the sealing portion 3b itself made of fluororesin is raised on the upper surface to form a convex curved surface. The electronic component 1c of FIG. 5 is an example in which a condenser lens 7a having a convex curved surface is laminated on the sealing portion 3a having a flat upper surface. The electronic component 1d of FIG. 6 is an example in which a condenser lens 7b is laminated on the upper surface of the ultraviolet light emitting element 2 and the condensing lens 7b is sealed from the middle to the bottom with a sealing portion 3d. Further, although not shown, an electronic element may be mounted and sealed on a chip-on-board type wiring base material.

Sealing with a fluororesin can be performed by, for example, the following methods a) to c). From the viewpoint of work efficiency, the melt sealing method of b) is preferable. In particular, when the upper surface of the sealing portion is formed to have a convexly raised shape as in the electronic component 1b of FIG. 4, the melt sealing method is preferable.
a) A method of applying a slurry or solution obtained by mixing a fluororesin with an appropriate solvent (hereinafter, may be referred to as a coating solution) and repeating the process of drying once or more (hereinafter, may be referred to as a coating method). ..
b) After molding the fluororesin into a sheet shape as needed, the fluororesin or its sheet is laminated on the electronic element mounting side of the wiring base material, and then the fluororesin or its sheet is heated to a temperature equal to or higher than the melting point to be melted. , Cooling method (hereinafter, may be referred to as melt sealing method).
c) A method in which the coating method and the melt sealing method are appropriately combined.

Examples of the solvent that can be used for preparing the coating liquid include ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone and methyl isobutyl ketone, ester solvents such as methyl acetate, ethyl acetate and butyl acetate, and terrorahydrofuran. Examples thereof include lactams such as cyclic ether and N-methyl-2-pyrrolidone.

The concentration of the fluororesin in the coating liquid is, for example, 1% by mass or more. The higher the concentration, the less the number of coatings can be applied. The preferable concentration is 5% by mass or more, and more preferably 7% by mass or more. The concentration is, for example, 50% by mass or less. The lower the concentration, the more the viscosity of the coating liquid can be prevented from being improved, and the processing accuracy can be improved. The preferable concentration is 40% by mass or less, and more preferably 30% by mass or less.

The heating temperature of the fluororesin when the melt sealing method is performed is preferably a temperature 10 ° C. or higher higher than the melting point of the fluororesin, and more preferably 20 ° C. or higher higher than the melting point. The upper limit of the heating temperature is, for example, 278 ° C., more preferably 250 ° C., even more preferably 200 ° C., and particularly preferably 150 ° C. At the above heating temperature, deterioration of the wiring base material due to heat can be suppressed.

The fluororesin may be heated in an oxygen-containing atmosphere such as the atmosphere, but it is preferably performed in an inert gas atmosphere such as a nitrogen atmosphere or an argon atmosphere. Further, the fluororesin may be heated under atmospheric pressure, but it is also preferable to heat the fluororesin under reduced pressure such as in vacuum. When the fluororesin is heated under reduced pressure, the bubbles remaining in the resin after sealing are reduced and the transparency is improved.

(5) Irradiation After sealing with the fluororesin as described above, the fluororesin is irradiated with radiation. By irradiating the fluororesin with radiation, the surface of the fluororesin (the surface of the sealing portion) can be cured, and even if the heat generated from the electronic element is large, the sealing portion can be suppressed from being thermally deformed. Therefore, for example, when a light emitting element is used as the electronic element, the orientation of the light does not change, and the same light can be extracted for a long period of time. In particular, when performing melt sealing, a fluororesin having good thermal fluidity, for example, a crystalline resin, particularly THV resin, may be used, and when sealed with such a fluororesin, the heat-resistant deformability after sealing is poor. It may be enough. Therefore, when performing melt sealing or when a fluororesin having good thermal fluidity is used, it is particularly effective to irradiate with radiation to enhance the heat-resistant deformability after sealing.

Examples of the radiation include ultraviolet rays, X-rays, γ-rays, electron beams, ion beams and the like, and electron beams are preferable. The electron beam is excellent in controlling the curing depth, and it becomes easy to enhance the heat-resistant deformability without adversely affecting the characteristics of the entire sealing portion.

The accelerating voltage in electron beam irradiation is, for example, 50 kV or more, preferably 70 kV or more, and more preferably 120 kV or more. The larger the accelerating voltage, the larger the curing depth. The accelerating voltage is, for example, 1000 kV or less, preferably 500 kV or less, and more preferably 300 kV or less. By preventing an excessive accelerating voltage, decomposition of the fluororesin can be prevented.

The absorbed dose due to the irradiation energy of the electron beam is, for example, 20 kGy or more, preferably 30 kGy or more, and more preferably 40 kGy or more. In particular, when the accelerating voltage is less than 120 kV, the absorbed dose is preferably 40 kGy or more, and when the accelerating voltage is 120 kV or more, the absorbed dose is preferably 20 kGy or more. Hardness can be increased by increasing the absorbed dose. The absorbed dose is, for example, 300 kGy or less, preferably 200 kGy or less, and more preferably 150 kGy or less.

The product of the product of the electron beam accelerating voltage (kV) and the absorbed dose (kGy) due to the electron beam irradiation energy is, for example, 1000 or more, preferably 3000 or more, and more preferably 4000 or more. The larger the product, the better the curing depth and the curing hardness, preferably both. The product is, for example, 100,000 or less, preferably 40,000 or less, and more preferably 30,000 or less. By reducing the product, decomposition of the fluororesin can be prevented and heat-resistant deformability can be improved.

When irradiating an electron beam, the fluororesin-sealed portion may be heated or cooled to an appropriate temperature. By controlling the temperature of the sealing portion, the surface hardening of the sealing portion can be appropriately controlled. The temperature of the sealing portion is, for example, 0 ° C. or higher and about 100 ° C. or lower, preferably 10 ° C. or higher and about 80 ° C. or lower, and more preferably 20 ° C. or higher and about 60 ° C. or lower.

In the electronic component of the present invention, since the fluororesin is cured by irradiation, the heat-resistant deformability of the sealed portion is good. Therefore, when the following heat resistance test is performed on the electronic component, the average deformation rate V of the fluororesin can be reduced. By using an electronic component having a small average deformation rate V, particularly a light emitting electronic component, it is possible to prevent a change in the orientation of light and to extract equivalent light over a long period of time. The average deformation rate V is, for example, less than 1.30, preferably less than 1.20, more preferably less than 1.15, and even more preferably less than 1.10.

In the heat resistance test, an electronic component having a wiring base material and a fluororesin filled in the wiring base material as a sealing portion is subjected to a temperature of 150 ° C. with the interface between the filled fluororesin and air facing down. It can be carried out by a method of holding for 60 hours.

The average deformation rate V is calculated by the following formula (1) by performing the above heat resistance test on an electronic component. In the formula, _RS is the standard before the heat resistance test (also simply called before holding) when the side projected area of the fluororesin protruding from the wiring base material per unit front projected area of the sealing portion is used as the normalized area. It represents the ratio of the normalized area to the normalized area after the heat resistance test (also simply after holding). For R _d , when the height of the fluororesin protruding from the wiring base material per unit front projection area of the sealing portion is taken as the normalized height, the normalized height after holding is compared with the normalized height before holding. Represents the height ratio. Before and after holding, the height of the fluororesin is the maximum height of the fluororesin protruding from the wiring base material from the surface of the wiring base material. The electronic element mounting surface or the electronic element mounting planned surface (p-electrode wiring forming surface, n-electrode wiring forming surface, etc.) of the electronic component is referred to as the front surface of the electronic component, and is orthogonal to the electronic element mounting surface or the electronic element mounting planned surface. The surface to be used is called the side surface.
Average deformation rate V = ( _RS × R _d ) ^1/2 (1)

The average deformation rate V may be calculated by performing a heat resistance test on a wiring base material, an electronic element, and an electronic component having a fluororesin that seals the electronic element, or by performing a heat resistance test on an evaluation model. As the evaluation model, a wiring base material and an electronic component having a fluororesin filled in the wiring base material can be used. The method of calculating the average deformation rate V using the evaluation model will be described below, but the average deformation rate V can be calculated in the same manner as when the evaluation model is used when using electronic components.

The evaluation model and the heat resistance test using the evaluation model will be described with reference to FIGS. 7 to 9. FIG. 7A is a front view of an example wiring base material 21 used in the evaluation model, and FIG. 7B is a side view of the wiring base material 21. The wiring base material 21 has a recess 21b inside the base material, and a p-electrode wiring 23 and an n-electrode wiring 24 are formed on the inner bottom surface (the surface of the base material) of the recess 21b. The recess 21b has an inner diameter ID, an outer diameter OD, and a side portion 22 corresponding to the side surface of the recess 21b. In the examples described later, a wiring base material having a recess having an inner diameter ID of 2.00 mm and an outer diameter OD of 3.04 mm and a height h of the wiring base material of 0.80 mm is used. The side portion 22 shown in FIG. 7 has a side surface (so-called slope) oblique to the opening surface of the recess 21b, but the recess of the wiring base material used in the evaluation model is the wiring of FIG. Like the recess 21c of the base material 4, it may have a side surface (so-called wall surface) 22c orthogonal to the recess opening surface. Further, the side portion 22 may be a part of the wiring base material or may be a member arranged in the recess of the wiring base material. When the wiring base material 21 is a wiring base material for LEDs, the side portion 22 may be referred to as a reflector.

FIG. 8A is a front view of the evaluation model 25 in which the recess 21b of the wiring base material 21 of FIG. 7A is filled with the fluororesin 26. It is preferable that the fluororesin is filled so that the fluororesin does not protrude from the outer frame of the recess 21b (also referred to as the outer frame of the side portion 22) onto the wiring base material 21. Before the heat resistance test, _RS and R _d in the formula (1) are the upper surface of the wiring base material 21 (the surface of the base material having the outer frame of the side portion 22, and the surface shown by 21a in FIG. 7). It is calculated using the projected area S _{2b of the} part covered with the fluororesin as seen from (corresponding to the front surface). When the fluororesin is filled so as not to protrude from the outer frame of the side portion 22 onto the wiring base material 21, the evaluation model usually has the shape shown in FIG. 8A, so that the projected area S _2b is the side portion. It is the area surrounded by the outer frame of 22 (the area S _{2b of} the portion shown by the line of sight in FIG. 8A).

In the heat resistance test, as shown in the side view of the evaluation model 25 in FIG. 8B, the interface between the fluororesin and the air in the evaluation model 25 is downward (that is, the front surface of the evaluation model 25 is directed downward). The evaluation model is held in the state) and performed. FIG. 9A is a front view of the evaluation model 25 after the heat resistance test, and FIG. 9B is a side view. As shown in the figure, the fluororesin is deformed by the heat resistance test. After the heat resistance test, _RS and R _d in the formula (1) are the upper surface of the wiring base material 21 (the surface of the base material having the outer frame of the side portion 22 and the surface shown by 21a in FIG. 7). It is calculated using the projected area S _{2a of the} portion covered with the fluororesin as seen from (corresponding).

The average deformation rate V is before and after the heat resistance test, (ray unit S _b in FIG. 8 (b), FIG. 9 (b ray portion S _a of)) side projected area of the fluorine resin that protrudes from the wiring substrate of the above formula As shown in (1), it is calculated using the values standardized by the projected areas S _2a and S _2b covered by the fluororesin in the front view. For the projected areas S _2a , S _2b , S _a , and S _b , more specifically, commercially available image analysis software is used using the digitized front and side views of the evaluation model before and after the heat resistance test. It can be determined by measuring the mass of the target portion using a paper on which the front view and the side view are printed. Here, the front view and the side view to be converted into electronic data or printed include, for example, a microscope image taken by using an optical microscope or the like, and the front view shows the direction facing the upper surface 21a of the wiring base material. The photographed view can be used, and the side view can be a view of the upper surface 21a taken from the side (a view taken from a direction parallel to the upper surface 21a), and the side view shows a plurality of side surfaces of the wiring substrate. All the images taken from the direction may be used (in this case, the calculation results are averaged), but if the required accuracy can be maintained as a representative value, the wiring substrate is taken from one direction. May be good.

On the other hand, when a microscope image corresponding to the front view is taken from the direction facing the upper surface 21a, the interface of the fluororesin protruding from the wiring base material with air is directed upward, and this is taken from directly above. Hereinafter, a microscope image obtained by photographing the evaluation model from the side may be referred to as a side microscope image, and a microscope image obtained by photographing the evaluation model from the front may be referred to as a front microscope image.

When the side microscope image of the evaluation model and the top microscope image of the evaluation model before and after the heat resistance test are used, _RS and R _d in the formula (1) are calculated by the following formulas.
Average deformation rate V = ( _RS × R _d ) ^1/2 (1)
_RS = Sn _a / Sn _b
Sn _a = S _a / S _2a
Sn _b = S _b / S _2b
R _d = dn _a / dn _b
dn _a = d _a / S _2a
dn _b = d _b / S _2b

In the above formula, S _a represents the area of the fluorine resin of the protruding portion from the wiring substrate in the side surface micrograph of evaluation model after the heat resistance test (after retention). S _b represents the area of the fluororesin in the portion protruding from the wiring substrate in the side microscope image of the evaluation model before the heat resistance test (before holding). S _2a represents the area of the portion covered with the fluororesin in front of the wiring base material of the front microscope image of the evaluation model after the heat resistance test (after holding). S _2b represents the area covered by the fluororesin in front of the wiring base material in the front microscope image of the evaluation model before the heat resistance test (before holding). Sn _a is the ratio of S _{a to} S _{2 a} , and represents the side surface area (normalized area after holding) of the fluororesin protruding from the wiring base material per unit front area of the sealing portion after holding. Sn _b is the ratio of S _b for S _2b, represents a side area of the fluorine resin that protrudes from the wiring substrate per unit frontal area of the sealing portion of the front holding (normalized area before holding).

In the above formula, d _a represents the height of the fluororesin portion projecting from the wiring substrate in the side surface micrograph of evaluation model after the heat resistance test (after retention). d _b represents the height of the fluororesin portion projecting from the wiring substrate in the side surface micrograph of evaluation models before the heat resistance test (before hold). dn _a is the ratio of d _{a to} S _{2 a} , and represents the height of the fluororesin protruding from the wiring base material per unit area of the sealed portion after holding (normalized height after holding). dn _b is the ratio of d _b for S _2b, represents the height of the fluororesin projecting from the wiring substrate per unit area of the sealing portion of the front holding (normalized height of the pre-held).

(6) Condensing Lens The electronic component of the present invention may have a condensing lens as shown in FIGS. 4, 5 and 6, and when it has a condensing lens, it is as shown in FIGS. 5 and 6. Condensing lens components 7a and 7b may be attached to the. The condenser lens components 7a and 7b are made of, for example, silica glass, borosilicate glass, or the like.

(7) Electronic Components As the electronic components of the present invention, electronic components provided with a light emitting element are preferable, and electronic components provided with an ultraviolet light emitting element are more preferable. The electronic component provided with the ultraviolet light emitting element can be used, for example, in an analyzer, a photocatalyst device, a phototherapy device, a bill appraisal device, an air / water sterilization purification device, a UV resin curing device, and the like.

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.

(1) Fluororesin Composition In the following examples, a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV) was used. The molar ratios of the tetrafluoroethylene-derived structural unit T, the hexafluoropropylene-derived structural unit H, and the vinylidene fluoride-derived structural unit V in THV were determined by the following NMR measurements.
Measuring device: JEOL ECZ-400
Sample: Approximately 60 mg / 0.8 ml ACT-d6
IS: 4-Chlorobenzodrifluoride 0.01 mL
Measurement mode: ¹ H, ¹⁹ F
Relaxation time: ¹ H 30 seconds, ¹⁹ F 20 seconds Number of units of constituent unit H: ¹⁹ Calculated by dividing the integration ratio of CF ₃ in F-NMR by 3 (CF ₃ integration ratio / 3)
Number of units of structural unit V: ¹ Calculated by dividing the integration ratio of CH ₂ in ¹ H-NMR by 2 (CH ₂ integration ratio / 2)
The number of units of the structural units T: ¹⁹ than the total area ratio of CF ₂ in the F-NMR, total calculated (CF ₂ by dividing the minus the CF ₂ constituent units derived from V and CF ₂ derived constituent unit H at 4 Integration ratio-Number of units of structural unit V x 2-Number of units of structural unit H x 2) / 4
The fluororesin used in the examples (trade name: Dynion THV221AZ; manufactured by 3M) has a molar ratio of the constituent unit T of 0.35, a molar ratio of the constituent unit H of 0.11, and a molar ratio of the constituent unit V of 0. It was .54.

Example 1
Fluororesin sheet is prepared by putting 3.5 g of fluororesin (trade name "THV221AZ") into a PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) chalet with a diameter of 48 mm and heating at a temperature of 200 ° C. for 3 hours. Then, a square sheet having a size of 3.0 × 3.0 mm was cut out with a utility knife.

The sheet is placed on an LED package (KD-LA9R48, manufactured by Kyocera Corporation), and the fluororesin is melted by heating at a temperature of 200 ° C. for 3 hours, and the inside of the package is filled (sealed) with the fluororesin. Obtained an electronic component (evaluation model). The shape of the LED package (KD-LA9R48, manufactured by Kyocera Corporation) is as shown in FIGS. 7 and 8, and the shape after sealing is roughly as shown in FIG.

The evaluation model obtained above was supplied with an electron beam device (CB250 / 30/20 mA, manufactured by Iwasaki Electric Co., Ltd.), and the evaluation model obtained above was supplied at a transport speed of 10 m / min. The sealed part) was irradiated with an electron beam. The electron beam accelerating voltage was set in the range of 100 to 250 kV, and the absorbed dose was set in the range of 25 to 100 kGy.
The heat resistance test of holding the fluororesin at a temperature of 150 ° C. for 60 hours was performed with the sealed fluororesin side of the evaluation model in which the fluororesin was cured with an electron beam facing down, and the average deformation rate V was examined. The average deformation rate V was obtained by printing the front view and the side view of the evaluation model on a paper surface and calculating the area of the target portion from the mass. Based on the average deformation rate V, the heat-resistant deformability was evaluated according to the following criteria. The results are shown in Table 1. When the average deformation rate V is less than 1.30, it can be said that the heat-resistant deformation property is good.
A: The average deformation rate V is less than 1.10.
B: The average deformation rate V is 1.10 or more and less than 1.15.
C: The average deformation rate V is 1.15 or more and less than 1.30.
D: The average deformation rate V is 1.30 or more.

The present invention can be used for manufacturing an electronic component provided with an electronic element, preferably for a light emitting element, and more preferably for an electronic component provided with an ultraviolet light emitting element.

1a, 1b, 1c, 1d, 25 Electronic components 2 Electronic elements (ultraviolet light emitting elements)
3a, 3b Sealing part 4 Wiring base material 5 Metal bump 6 Ultraviolet light emitting element mounting Wiring base material 7a, 7b Condensing lens component 10 p electrode 11 n electrode 12 p layer 13 Active layer 14 n layer 15 Element substrate 21 Wiring Base material 21a Front surface (upper surface) of wiring base material
21b, 21c Recesses in the wiring base material 22, 22c Side parts of the recesses in the wiring base material 23 p Wiring for electrodes 24 n Wiring for electrodes 25 Evaluation model 26 Fluororesin h Height of wiring base material S _a , S _b Wiring base material side projected area of the protruded fluororesin from S _2a, the height of the S _2b projected area d _a front viewed from portion covered with a fluorine resin of the wiring substrate, portions of the fluororesin protruding from d _b wiring substrate

When irradiating an electron beam, the fluororesin-sealed portion may be heated or cooled to an appropriate temperature. By controlling the temperature of the sealing portion, the surface hardening of the sealing portion can be appropriately controlled. The temperature of the sealing portion is, for example, 0 ° C. or higher and about 100 ° C. or lower, preferably 10 ° C. or higher and about 80 ° C. or lower, and more preferably 20 ° C. or higher and about 60 ° C. or lower.

Claims (7)

The process of covering the electronic element attached to the wiring substrate with fluororesin,
A method for manufacturing an electronic component, which comprises a step of irradiating the fluororesin covering the electronic element with radiation. The production method according to claim 1, wherein the fluororesin is a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer. The manufacturing method according to claim 1 or 2, wherein the radiation is an electron beam. The manufacturing method according to claim 3, wherein the accelerating voltage of the electron beam is 50 kV or more. The production method according to claim 3 or 4, wherein the irradiation energy of the electron beam is 20 kGy or more in absorbed dose. It is an electronic component having a wiring base material and a fluororesin filled in the wiring base material as a sealing portion.
When the electronic component is held at a temperature of 150 ° C. for 60 hours with the interface between the filled fluororesin and air facing down, the average deformation rate V calculated by the following formula (1) is less than 1.30. Electronic components that are.
Average deformation rate V = ( _RS × R _d ) ^1/2 (1)
(In the formula, _RS is the standardized area of the fluororesin protruding from the wiring base material per unit frontal projected area of the sealing portion, and the _RS is the said after holding with respect to the standardized area before holding. Represents the ratio of standardized area, and R _d is the retention with respect to the standardized height before holding when the height of the fluororesin protruding from the wiring base material per unit front projected area of the sealing portion is defined as the normalized height. It represents the later ratio of the standardized height. The electronic element mounting surface or the electronic element mounting planned surface of the electronic component is referred to as the front surface of the electronic component, and the surface orthogonal to the electronic element mounting surface or the electronic element mounting planned surface is the side surface. ) The electronic component according to claim 6, wherein the fluororesin is a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer.

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