JP2002173675A - Fluorescence particle having coated layer and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fluorescent particle having a coated layer with environmental resistance and ultraviolet resistance. SOLUTION: This fluorescent particle (1) has a coated layer (2) which comprises a glass such as a polymetalloxane having light transmission, etc., or a ceramic such as nitrogen silicon-based ceramic and is formed approximately on the whole surface. The fluorescent particle is provided with environmental resistance and ultraviolet resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to fluorescent particles for converting the wavelength of received light, particularly fluorescent particles having a coating layer having resistance to ultraviolet light or heat, and a method for producing the same.

[0002]

2. Description of the Related Art When a semiconductor light emitting device having a large band gap (energy gap) is used, a semiconductor light emitting device which emits light at a relatively short wavelength from visible light having a short wavelength to an ultraviolet region or a near ultraviolet region can be realized. it can. Semiconductor light emitting devices that generate ultraviolet light are made of a nitrogen gallium-based compound semiconductor such as GaN, GaAlN, InGaN, and InGaAlN, and have a small size, low power consumption,
It can be used for a new solid-state ultraviolet light source having various advantages such as a long life.

[0003]

Generally, a semiconductor light emitting device is covered with a resin encapsulant composed of an organic polymer compound in which elements such as carbon, hydrogen, oxygen, and nitrogen are bonded in a mesh. It is known that when these ultraviolet rays and the like are irradiated on the resin sealing body that forms the outer enclosure made of the base resin, the joint of the organic polymer is cut, and various optical and chemical properties are deteriorated. I have. For example, a blue light emitting diode chip of GaN (gallium nitride) has a wavelength of 365 nm.
Since the ultraviolet light is emitted to the extent, the resin sealing body gradually turns yellow around the light emitting diode chip having a high light intensity, and a coloring phenomenon occurs. Therefore, the visible light emitted from the light emitting diode chip is absorbed and attenuated by the colored portion. Furthermore, since the moisture resistance decreases and the ion permeability increases with the deterioration of the resin sealing body, the light emitting diode chip itself also deteriorates, and as a result, the light emission intensity of the light emitting diode device decreases synergistically.

[0004] Since the resin sealing body having low heat resistance is yellowed and colored, light emitted from the light emitting diode chip is attenuated when passing through the resin sealing body. For example, high forward voltage
GaN (gallium nitride) blue light emitting diode chip,
Even at relatively low forward currents, the power loss is large and the chip temperature rises significantly during operation. It is also known that resins are generally deteriorated when heated to a high temperature, causing yellowing and coloring. Therefore, when a GaN light-emitting diode chip is used in a conventional light-emitting diode device, the resin gradually turns yellow and is colored from the portion in contact with the high-temperature light-emitting diode chip, so that the appearance quality and light emission intensity of the light-emitting diode device gradually decrease. As described above, in the conventional light emitting diode device, the number of kinds of materials to be selected, the reliability is reduced, the light conversion function is incomplete, and the product price is increased.

FIG. 3 is a cross-sectional view of a conventional light emitting diode device for converting the wavelength of light emitted from a light emitting diode chip with a fluorescent substance (7a). In the light emitting diode device (20) shown in FIG. 3, a light emitting diode chip is provided on the bottom surface (3b) of the concave portion (3a) of the external terminal (3) as a cathode lead.
(12) is fixed, and the cathode electrode of the light emitting diode chip (12) is connected to the external terminal (3) on the cathode side by the lead wire (5).
Is connected to the upper end (9a). The anode electrode of the light emitting diode chip (12) is connected to the upper end (9b) of the external terminal (4) as a lead on the anode side by a thin lead wire (6). Light emitting diode chip (12) fixed in the recess (3a)
Is covered with a light-transmitting protective resin (7) filled in the recess (3a) and mixed with the fluorescent substance (7a). Light-emitting diode chip (12), concave part (3
a) and the upper end (9a), the upper end of the external terminal (4) on the anode side
(9b), the fine lead wires (5, 6) are more light-transmitting sealing resin
It is enclosed in (8).

When a voltage is applied between the cathode-side external terminal (3) and the anode-side external terminal (4) of the light emitting diode device (20) and the light emitting diode chip (12) is energized, the light emitting diode chip (12) is turned on. Light emitted from 12) is a protective resin (7)
After passing through the inside and reflecting off the side wall (3c) of the concave portion (3a) of the external terminal (3), the light-emitting diode device (2) passes through the transparent sealing resin (8).
It is released outside of 0). In addition, the light emitting diode chip (1
The light emitted from the upper surface of 2) is not reflected on the side wall (3c) of the concave portion (3a) but is emitted directly to the outside of the light emitting diode device (20) through the protective resin (7) and the sealing resin (8). There is also light. At the tip of the sealing resin (8), a lens part (8a) is formed, and the sealing resin (8)
Light passing through the inside is condensed by the lens portion (8a), and the directivity is enhanced. When the light emitting diode chip (12) emits light, light emitted from the light emitting diode chip (12) is converted into a different wavelength by the fluorescent substance (7a) mixed in the protective resin (7) and emitted. As a result, light having a different wavelength from the light emitted from the light emitting diode chip (12) is emitted from the light emitting diode device (20).

[0007]

SUMMARY OF THE INVENTION A light emitting diode chip
There is a problem that the coating resin and the phosphor are deteriorated by the ultraviolet component generated from (12). Generally, carbon, hydrogen, oxygen,
The protective resin (7) and the encapsulating resin (8), which are composed of an organic polymer compound in which elements such as nitrogen are bonded in a network, are cut at the joint of the organic polymer when irradiated with ultraviolet rays, It is known that the optical properties and chemical properties of are deteriorated. For example, a blue light-emitting diode chip of GaN (gallium nitride) has a light-emitting component in the ultraviolet wavelength range of 380 nm or less in addition to the visible light component, so that the coating resin gradually turns yellow from the periphery of the light-emitting diode chip with strong light intensity. When the coloring phenomenon occurs, the visible light emitted from the light emitting diode chip is absorbed and attenuated by the colored portion. Furthermore, as the moisture resistance decreases with the deterioration of the coating resin, and the ion permeability increases, the light emitting diode chip itself also deteriorates. As a result, the light emitting intensity of the light emitting diode device (20) decreases synergistically. .

Also, there are phosphors that are deteriorated by ultraviolet rays, like the coating resin. For example, it is known that a zinc sulfide-based phosphor undergoes photodecomposition by radiation or ultraviolet rays to cause a so-called "blackening" phenomenon in which zinc is released. When the phosphor in the coating resin undergoes photolysis, the light emission intensity of the light emitting diode device (20) is significantly reduced.

In order to prevent the deterioration of the coating resin and the phosphor due to ultraviolet rays, a method of mixing an ultraviolet absorbing substance into the coating resin is conceivable. However, it does not absorb the visible light component itself and adversely affects the intrinsic properties of the coating resin. Care must be taken to select UV absorbers that will not be given. In addition, when an ultraviolet absorbing material is used, the number of additional materials and the number of working processes are increased, so that there is a problem that the product price increases.

Furthermore, since an ultraviolet light emitting diode chip that emits ultraviolet light cannot be used, there is a problem that the selection of the material of the phosphor and the light emitting characteristics of the light emitting diode device are greatly restricted. Ultraviolet phosphors excited by ultraviolet light used in fluorescent lamps or mercury lamps have been developed and improved for a long time. The body is in practical use. It is expected that a combination of an ultraviolet light emitting diode chip and a phosphor for ultraviolet light will provide a light emitting diode device with a brighter and more varied color tone. However, in a conventional light emitting diode device in which the resin is deteriorated by ultraviolet light, an ultraviolet light emitting diode chip cannot be used,
Excellent phosphors are not available. As described above, in the conventional light emitting diode device, when the phosphor is mixed in the resin, the above-described problem occurs. Therefore, the selection of the material type is reduced, the reliability is reduced, the light conversion function is incomplete, and the product price is increased. May cause inconvenience.

An object of the present invention is to provide a fluorescent particle having a coating layer having environmental resistance and ultraviolet resistance, and a method for producing the same.

[0012]

The fluorescent particles (1) according to the present invention, having a coating layer (2) made of light-transmitting glass or ceramic and formed over almost the entire surface, are resistant to environmental and ultraviolet light. It has the nature. In the embodiment of the present invention, the glass is, for example, polymetalloxane, and the ceramic is a nitrogen silicon-based ceramic. The fluorescent particles (1) may be sealed in a resin material having optical transparency. Coating layer
(2) consists of polymetalloxane formed from metal alkoxide. Metal alkoxides include Ti (OCH ₃ ) ₄ , Ti (OC
_{2 H 5) 4, Ti (} iso-OC 3 H 7) 4, Ti (OC 4 H 9) 4 and the like single metal alkoxide or La of _{[Al (iso-OC 3 H} 7) 4) 3, Mg [Al (iso-OC
_{3 H 7) 4] 2,} Mg [Al (sec-OC 4 H 9) 4] 2, Ni [Al (iso-OC 3 H 7) 4]
₂ , bimetal alkoxides such as Ba [Zr ₂ (C ₂ H ₅ ) ₉ ] ₂ and (OC ₃ H ₇ ) ₂ Zr [Al (OC ₃ H ₇ ) ₄ ] ₂ or polymetal alkoxides.

The method for producing the fluorescent particles (1) having the coating according to the present invention comprises the steps of dissolving a ceramic precursor such as a metal alkoxide or polysilazane in an organic solvent to form a sol; Forming a film of a metal alkoxide or a ceramic precursor on the surface of the fluorescent material, and baking the film in a temperature range of, for example, 120 to 160 ° C. to form a coating layer of glass or ceramic on the surface of the fluorescent material (2 ) Is formed.

In the embodiment of the present invention, a step of forming a coating layer (2) mainly by a metaloxane bond, a step of forming a coating layer (2) mainly by a gel-like siloxane bond, Coating layer made of polymetalloxane by applying sol-gel method to metal alkoxide (2)
And forming a coating layer (2) made of polymetalloxane by hydrolytic polymerization of a metal alkoxide or a solution containing a metal alkoxide by a sol-gel method.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fluorescent particle having a coating layer according to the present invention and a method for producing the same will be described below with reference to FIGS.

As shown in FIG. 1, the fluorescent particles according to the present invention
(1) is made of glass or ceramic having optical transparency.
And has a coating layer (2) formed over substantially the entire surface.
You. Glass is, for example, polymetalloxane,
The lock is a nitrogen silicon-based ceramic. Polymetalloxane
Is Ti (OCH_Three)_Four, Ti (OC_TwoH_Five)_Four, Ti (iso-OC_ThreeH₇)_Four, Ti (OC_FourH
₉)_FourSuch as a single metal alkoxide or La [Al (iso-OC_ThreeH₇)_Four)
_Three, Mg [Al (iso-OC_ThreeH₇)_Four] _Two, Mg [Al (sec-OC_FourH₉)_Four]_Two, Ni
[Al (iso-OC_ThreeH₇)_Four]_Two, Ba [Zr_Two(C_TwoH_Five)₉]_Two, (OC_ThreeH₇)_TwoZr [Al
(OC_ThreeH₇)_Four]_TwoBimetallic alkoxide or polymetallic alkoxide
It is formed from a metal alkoxide that is a cooxide. fluorescence
About 6 mol% of Ce (cerium) was added as an activator to the particles (1).
YAG (Yttrium Aluminum Garnet)
G, chemical formula Y_ThreeAl_FiveO₁₂, Excitation wavelength peak about 450 nm, emission
A yellow-green light having a light wavelength peak of about 540 nm) is used.

The fluorescent particles (1) coated on the coating layer (2) have environmental resistance and ultraviolet resistance. Even if near-ultraviolet light generated from the light emitting diode chip (12) is irradiated for a relatively long time and the temperature rises, the coating layer (2) generates yellowing and coloring that attenuate light emission from the light emitting diode chip (12). do not do. The fluorescent particles (1) according to the present invention have the protective resin shown in FIG.
(7) or when mixed into the sealing resin (8), 365 nm to 550
A gallium nitride-based semiconductor light emitting device that emits light at a light wavelength of nm can receive light from the semiconductor light emitting device (2) and convert the wavelength. Although the sealing resin (8) is made of an epoxy resin that is not very excellent in ultraviolet light resistance, if the wavelength is converted by the fluorescent particles (1), yellowing and coloring of the sealing resin (8) are also well prevented. , Maintain environmental resistance and have longer life.

When producing the fluorescent particles (1) having the coating according to the present invention, a fluidized bed type coating apparatus (1) shown in FIG.
Prepare 0). The fluidized bed type coating apparatus (10) includes a cylindrical barrel (11), and a gas inlet (17) and a gas outlet (13) are provided at the bottom and the top of the barrel (11), respectively.
Above the gas inlet (17), a breathable wire mesh (screen)
A table (14) formed by
4) The fluorescent particles (1) are arranged on the upper side. A nozzle (15) connected to the supply pipe (16) is provided above the table (14).

In forming the coating layer (2), a sol is formed by dissolving a ceramic precursor such as a metal alkoxide or polysilazane in an organic solvent, and then the sol is supplied through a supply pipe (16) and a nozzle (15). Spray onto the fluorescent particles (1). An inert gas such as argon is supplied from the gas inlet (17) into the barrel (11) through the table (14) so that the sol particles are uniformly attached to the entire surface of the granular fluorescent particles (1). Fluorescent particles
Float (1) upward. If the inside of the barrel (11) is at a low temperature below normal temperature, air may be used instead of the inert gas. Thereafter, the sol attached to the surface of the fluorescent particles (1) is dried, and the coating is baked in a temperature range of, for example, 120 to 160 ° C. As described above, the amorphous metal oxide composed of glass or ceramic is formed by subjecting the sol-gel method to hydrolysis polymerization, and vitrifying or ceramicizing at a low temperature mainly based on a metaloxane bond or a gel-like siloxane bond. An article coating layer (2) can be formed on the surface of the fluorescent particles (1). The coating layer (2) is made of a polymetalloxane or a silicon nitride ceramic.

A coating glass material or a ceramic precursor (perhydropolysilazane) starting from a solution obtained by hydrolytic polymerization of a solution containing a metal alkoxide, a ceramic precursor or a metal alkoxide by a sol-gel method, or a combination thereof. Etc.). The coating-type starting material is usually in a liquid state, but when heated in air or an oxygen atmosphere, the decomposition of the components or the absorption of oxygen causes the metaloxane of metal oxide.
Produce a transparent solid glass layer mainly composed of bonds. For example, SiO ₂ (silicon oxide) due to decomposition of components or absorption of oxygen
A transparent solid glass layer mainly composed of siloxane bonds is formed.

When the sol changes into a gel, the sol particles form a siloxane bond with each other to form a skeleton structure of the gel. Further, the obtained glass gel film is fired to increase the number of siloxane bonds between the sol particles, and a porous glass gel film having high strength can be obtained by firing at a low temperature. Metalloxane is represented by the general formula: M (OR) n, where M is silicon (Si),
At least one metal selected from the group consisting of aluminum (Al) or zinc (Zn), R is the same or different carbon number of 1 to 1
22 saturated or unsaturated aliphatic hydrocarbon groups, n refers to a number corresponding to the valency of the metal.

In the sol-gel method, a solution of a metal compound such as an alkoxide, a metal organic compound or an inorganic compound as a starting material is hydrolyzed and polycondensed to form a sol.
By further proceeding the reaction and hydrolyzing the gelled reactant, a solid metal oxide is obtained. In the sol-gel method of forming a silica glass film, when using an alkoxide of silicon as a metal oxide, for example, tetraethoxysilane, dissolve the alkoxide in a solvent such as alcohol, add a small amount of acid and water, and add the following in a solution. A sol is formed according to the reaction formula: Hydrolysis reaction: Si (OR) ₄ + 2H ₂ O → Si (OH) ₄ + 4ROH Dehydration condensation reaction: nSi (OH) ₄ → [SiO ₂ ] _n + 2nH ₂ O

In the present invention, the coating layer (2) made of glass or ceramic having optical transparency is formed over substantially the entire surface of the fluorescent particles (1), but the coating layer (2) is formed completely on the entire surface. Fluorescent particles (1)
The opening which does not cover the surface may be partially formed in the coating layer (2).

[0024]

As described above, in the present invention, fluorescent particles having environmental resistance and ultraviolet light resistance can stably convert the wavelength of light without being deteriorated for a long time. Further, it can be mixed into a light-transmitting resin or glass.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a fluorescent particle having a coating layer according to the present invention.

FIG. 2 is a sectional view of a fluidized bed type coating apparatus.

FIG. 3 is a cross-sectional view of a conventional light emitting diode device.

[Explanation of symbols]

(1) Fluorescent particles, (2) coating layer, (3) first external terminal, (3a) recess, (3b) bottom, (3c)
・ Side wall, (4) ・ ・ Second external terminal, (5) ・ ・ First thin lead wire, (6) ・ ・ Second thin lead wire, (8) ・ ・ Coating body (sealing resin), ( 9a, 9b) · · · top end, (10) · · · fluidized bed type coating equipment, (11) · · · barrel, (12) · · · semiconductor light emitting element (light emitting diode chip), (13) · · · gas outlet, (14) table, (15) nozzle,
(16) ·· Supply pipe, (17) ·· Gas inlet, (20) ·· Light emitting diode device (light emitting semiconductor device),

Claims (14)

[Claims] 1. A fluorescent particle comprising a coating layer made of glass or ceramic having a light transmitting property and formed over substantially the entire surface. 2. The fluorescent particles according to claim 1, wherein the glass is a polymetalloxane. 3. The phosphor particles according to claim 1, wherein the ceramic is a nitrogen silicon-based ceramic. 4. The fluorescent particles according to claim 1, which are sealed in a resin material having a light transmitting property. 5. The fluorescent particles according to claim 1, wherein the coating layer is made of a polymetalloxane formed from a metal alkoxide. 6. The metal alkoxide is Ti (OCH_Three)_Four, T
i (OC_TwoH_Five)_Four, Ti (iso-OC_ThreeH ₇)_Four, Ti (OC_FourH₉)_FourEtc single metal
Alkoxide or La [Al (iso-OC_ThreeH₇)_Four)_Three, Mg [Al (iso-O
C_ThreeH₇)_Four]_Two, Mg [Al (sec-OC_FourH₉)_Four]_Two, Ni [Al (iso-OC
_ThreeH₇)_Four]_Two, Ba [Zr_Two(C_TwoH_Five)₉]_Two, (OC_ThreeH₇)_TwoZr [Al (OC_ThreeH₇)_Four]_Two
Bimetallic alkoxide or multimetal alkoxide
The fluorescent particles according to claim 5. 7. A step of forming a sol by dissolving a metal alkoxide or a ceramic precursor in an organic solvent, and spraying the sol on a granular fluorescent substance to coat the surface of the fluorescent substance with the metal alkoxide or the ceramic precursor. Forming a coating layer made of glass or ceramic on the surface of the fluorescent substance by sintering the coating film. 8. The method for producing fluorescent particles having a coating according to claim 7, comprising a step of forming the coating layer mainly by a metaloxane bond. 9. The method for producing fluorescent particles according to claim 7, further comprising a step of forming the coating layer mainly by a gel-like siloxane bond. 10. The method for producing fluorescent particles according to claim 7, further comprising a step of subjecting the metal alkoxide to a sol-gel method to form the coating layer made of polymetalloxane. 11. The method according to claim 7, further comprising a step of forming a coating layer made of polymetalloxane by hydrolytic polymerization of a metal alkoxide or a solution containing a metal alkoxide by a sol-gel method. A method for producing the fluorescent particles according to the above. 12. The method according to claim 12, wherein the metal alkoxide is Ti (OC
H_Three)_Four, Ti (OC_TwoH_Five)_Four, Ti (iso-OC _ThreeH₇)_Four, Ti (OC_FourH₉)_FourEtc. simply
Monometal alkoxide or La [Al (iso-OC_ThreeH₇)_Four)_Three, Mg [Al
(iso-OC_ThreeH₇)_Four]_Two, Mg [Al (sec-OC_FourH₉)_Four]_Two, Ni [Al (iso−
OC_ThreeH₇)_Four]_Two, Ba [Zr_Two(C_TwoH_Five)₉]_Two, (OC_ThreeH₇)_TwoZr [Al (OC_ThreeH₇)_Four]
_TwoAlkoxide or multimetal alkoxide such as
The method for producing fluorescent particles according to claim 7 or 8, wherein 13. The method according to claim 7, wherein the ceramic precursor is polysilazane. 14. The temperature for firing the coating is 120 to 1
The method for producing fluorescent particles according to claim 7, wherein the temperature is 60 ° C.