JP7325431B2 - Method for manufacturing phosphor plate and light emitting device using phosphor plate - Google Patents

Description

The present invention relates to a method for manufacturing a phosphor plate and a light emitting device using the phosphor plate .

Various developments have been made in phosphor plates so far. As this type of technology, for example, the technology described in Patent Document 1 is known. Patent Literature 1 describes a plate-shaped luminous color conversion member in which an inorganic phosphor is dispersed in SiO ₂ -based glass (Fig. 4 of Patent Literature 1, claim 1).

JP 2010-132923 A

However, as a result of investigation by the present inventors, it has been found that there is room for improvement in terms of luminous efficiency in the plate-shaped luminous color conversion member described in Patent Document 1 above.

As a result of further investigation by the present inventors, it was found that a phosphor plate capable of obtaining stable luminous efficiency can be realized by combining appropriate materials of α-SiAlON phosphor and alumina (Al ₂ O ₃ ) to form a composite. and completed the present invention.

According to the invention,
Provided is a phosphor plate made of a composite containing an α-sialon phosphor and a sintered body containing alumina.

Also according to the present invention,
a group III nitride semiconductor light emitting device;
the phosphor plate provided on one surface of the group III nitride semiconductor light emitting device;
A light emitting device is provided, comprising:

ADVANTAGE OF THE INVENTION According to this invention, the phosphor plate excellent in luminous efficiency and the light-emitting device using the same are provided.

The above objectives, as well as other objectives, features and advantages, will become further apparent from the preferred embodiments described below and the accompanying drawings below.

It is a schematic diagram which shows an example of a structure of the phosphor plate of this embodiment. 1A is a cross-sectional view schematically showing the configuration of a flip-chip light-emitting device, and FIG. 1B is a cross-sectional view schematically showing the configuration of a wire-bonding light-emitting element. 1 is a schematic diagram of an apparatus for measuring emission spectra of complexes; FIG. 1 shows emission spectra obtained from composites of Examples 1 and 2 and Comparative Example 1. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In addition, in all the drawings, the same constituent elements are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Also, the drawings are schematic diagrams and do not correspond to actual dimensional ratios.

An outline of the phosphor plate of this embodiment will be described.
The phosphor plate of this embodiment is composed of a plate-like member made of a composite containing an α-sialon phosphor and a sintered body containing alumina.

The phosphor plate can function as a wavelength converter that converts the irradiated blue light into orange light and emits light.

According to the findings of the present inventors, a phosphor capable of obtaining stable luminous efficiency can be obtained by combining appropriate materials of α-sialon phosphor and alumina (Al ₂ O ₃ ) as components constituting the composite. It has been found that a plate can be realized.

Although the detailed mechanism is not clear, by appropriately reducing the difference in the refractive index between the α-SiAlON phosphor and _alumina , the α-SiAlON It is considered that the light emitted from the phosphor is easily extracted and the light conversion efficiency is increased. Also, compared with the case of using glass powder, the use of alumina can increase the thermal conductivity. As a result, the decrease in emission intensity due to heating is suppressed, so that the phosphor plate of this embodiment can be applied to a high-output light-emitting element.

On the other hand, if the refractive index difference is too small as in the case of the combination of YAG phosphor and alumina, light scattering becomes difficult, and it is necessary to increase the phosphor content in order to prevent the transmission of blue light. On the other hand, the refractive index difference between the α-SiAlON phosphor and alumina is moderately large, promoting the scattering of blue light. It is thought that it can emit light.

Here, as representative values of the refractive index of each component, α-SiAlON phosphor: about 2, YAG phosphor: about 1.8, Al ₂ O ₃ : about 1.7, and SiO ₂ : about 1.4 are known. It is

According to the phosphor plate, when blue light with a wavelength of 455 nm is irradiated, the peak wavelength of wavelength-converted light emitted from the phosphor plate is preferably 585 nm or more and 605 nm or less. Further, according to this, by combining a phosphor plate with a light emitting element that emits blue light, a light emitting device that emits orange light with high brightness can be obtained.

The configuration of the phosphor plate of this embodiment will be described in detail.

The α-sialon phosphor and alumina are mixed in the composite constituting the phosphor plate. Mixing means a state in which the α-sialon phosphor is dispersed in alumina serving as a base material (matrix phase). That is, the composite may have a structure in which α-SiAlON phosphor particles are dispersed between and/or within crystal grains of a (poly)crystal that constitutes the base material. The α-sialon phosphor particles may be uniformly dispersed in the base material (alumina sintered body).

(α-type Sialon phosphor)
The α-sialon phosphor of this embodiment contains an α-sialon phosphor containing an Eu element represented by the following general formula (1).
(M) _m(1-x)/p (Eu) _mx/2 (Si) _12-(m+n) (Al) _m+n (O) _n (N) _16-n General formula (1)

In the above general formula (1), M represents one or more elements selected from the group consisting of Li, Mg, Ca, Y and lanthanide elements (excluding La and Ce), p is the valence of the M element, 0 <x<0.5, 1.5≦m≦4.0, and 0≦n≦2.0. For example, n may be 2.0 or less, 1.0 or less, or 0.8 or less.

The solid solution composition of α-type Sialon is such that m Si—N bonds in the α-type silicon nitride unit cell (Si1 ₂ N ₁₆ ) are converted to Al—N bonds, and n Si—N bonds are converted to Al—O bonds. In order to replace and maintain electroneutrality, m/p cations (M, Eu) penetrate into the crystal lattice and form a solid solution, represented by the above general formula. In particular, when Ca is used as M, α-sialon is stabilized in a wide composition range, and by substituting a part of it with Eu, which is the emission center, it is excited by light in a wide wavelength range from ultraviolet to blue, and yellow to A phosphor is obtained which exhibits an orange visible emission.

In general, the solid solution composition of α-sialon cannot be strictly specified by composition analysis or the like because of the second crystalline phase different from the α-sialon and the amorphous phase that is inevitably present. The crystal phase of α-sialon is preferably a single phase of α-sialon, and may contain other crystal phases such as β-sialon, aluminum nitride or its polytypoid, Ca ₂ Si ₅ N ₈ , CaAlSiN ₃ .

As a method for producing an α-sialon phosphor, there is a method of heating and reacting a mixed powder composed of silicon nitride, aluminum nitride and a compound of an interstitial solid-solution element in a high-temperature nitrogen atmosphere. A part of the constituent components forms a liquid phase in the heating process, and a solid solution of α-sialon is produced by moving the substance to this liquid phase. In the synthesized α-sialon phosphor, a plurality of equiaxed primary particles are sintered to form massive secondary particles. The primary particles in the present embodiment refer to the smallest particles that have the same crystal orientation within the particles and can exist independently.

The lower limit of the average particle size of the α-sialon phosphor is preferably 5 μm or more, more preferably 10 μm or more. Moreover, the upper limit of the average particle size of the α-sialon phosphor is preferably 30 μm or less, more preferably 20 μm or less. The average particle size of the α-sialon phosphor is the size of the secondary particles. By setting the average particle size of the α-sialon phosphor to 5 μm or more, the transparency of the composite can be further enhanced. On the other hand, by setting the average particle size of the α-sialon phosphor to 30 μm or less, it is possible to suppress the occurrence of chipping when the phosphor plate is cut with a dicer or the like.

Here, the average particle size of the α-SiAlON phosphor refers to a volume-based particle size distribution measured by a laser diffraction scattering particle size distribution measurement method (manufactured by Beckman Coulter, LS13-320). It refers to the particle diameter D50 at 50% of the cumulative passing fraction (accumulated passing fraction).

The lower limit of the content of the α-sialon phosphor is, for example, 5 Vol % or more, preferably 10 Vol % or more, more preferably 15 Vol % or more in terms of volume with respect to the entire composite. As a result, the emission intensity of the thin phosphor plate can be increased. Also, the light conversion efficiency of the phosphor plate can be improved. On the other hand, the upper limit of the content of the α-sialon phosphor is, for example, 50 Vol % or less, preferably 45 Vol % or less, and more preferably 40 Vol % or less in terms of volume with respect to the entire composite. A decrease in thermal conductivity of the phosphor plate can be suppressed.

Since the alumina in the sintered body absorbs less visible light, it can increase the emission intensity of the phosphor plate. In addition, since alumina has high thermal conductivity, the heat resistance of the phosphor plate containing alumina can be improved. Furthermore, since alumina is excellent in mechanical strength, it is possible to enhance the durability of the phosphor plate.

From the viewpoint of light extraction efficiency, the alumina in the sintered body preferably contains few impurities. For example, in the alumina in the sintered body, the purity of the Al ₂ O ₃ compound can be, for example, 98% wt or more, preferably 99% wt or more.

Alumina in the sintered body may contain one or more selected from the group consisting of α-alumina and γ-alumina. Thereby, the light conversion efficiency of the phosphor plate can be improved.

The lower limit of the content of α-sialon phosphor and alumina is, for example, 95 Vol % or more, preferably 98 Vol % or more, more preferably 99 Vol % or more in terms of volume with respect to the entire composite. That is, it means that the composite constituting the phosphor plate contains the α-sialon phosphor and alumina as main components. As a result, heat resistance and durability can be improved, and stable luminous efficiency can be achieved. On the other hand, the upper limit of the content of the α-sialon phosphor and alumina is not particularly limited, but may be, for example, 100 Vol % or less in terms of volume with respect to the entire composite.

The lower limit of the thermal conductivity of the phosphor plate is, for example, 10 W/m·K or more, preferably 15 W/m·K or more, more preferably 20 W/m·K or more. As a result, high thermal conductivity can be achieved, and a phosphor plate with excellent heat resistance can be achieved. On the other hand, the upper limit of the thermal conductivity of the phosphor plate is not particularly limited, but may be, for example, 40 W/m·K or less.

In recent years, it is known that the temperature of phosphors tends to rise as the brightness of light sources increases. Even in such a case, it is possible to stably emit high-brightness orange light by using a phosphor plate having excellent thermal conductivity.

At least the main surface of the phosphor plate, or both the main surface and the back surface may be surface-treated. Examples of the surface treatment include grinding using a diamond whetstone or the like, lapping, polishing such as polishing, and the like.
The surface roughness Ra of the main surface of the phosphor plate is, for example, 0.1 μm or more and 2.0 μm or less, preferably 0.3 μm or more and 1.5 μm or less.
On the other hand, the surface roughness Ra of the back surface of the phosphor plate is, for example, 0.1 μm or more and 2.0 μm or less, preferably 0.3 μm or more and 1.5 μm or less.
By setting the surface roughness to be equal to or less than the upper limit, it is possible to suppress light extraction efficiency and variations in light intensity in the in-plane direction. By setting the surface roughness to be equal to or higher than the lower limit, it is expected that the adhesiveness to the adherend can be enhanced.

In the phosphor plate, the upper limit of light transmittance for blue light of 450 nm is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less. As a result, transmission of blue light through the phosphor plate can be suppressed, so that orange light with high brightness can be emitted. By appropriately adjusting the content of the α-sialon phosphor and the thickness of the phosphor plate, the light transmittance for blue light of 450 nm can be reduced.
Although the lower limit of the light transmittance for blue light of 450 nm is not particularly limited, it may be, for example, 0.01% or more.

The manufacturing process of the phosphor plate of this embodiment will be described in detail.

The method for manufacturing a phosphor plate of the present embodiment comprises a step (1) of mixing alumina powder and α-sialon phosphor powder containing at least Eu element as a luminescent center, and and a step (2) of heating the mixture with above 1300° C. and below 1700° C. to sinter the dense composite.

In step (1), the alumina powder and the α-sialon phosphor powder used as raw materials preferably have as high a purity as possible, and the impurities of elements other than the constituent elements are preferably 0.1% or less. Further, since the phosphor plate of the present invention is densified by sintering the alumina powder, it is preferable to use fine alumina powder, and the average particle size of the alumina powder used as the raw material is 1 μm or less. preferable. A variety of dry and wet methods can be used for mixing the raw material powder, but a method that minimizes the pulverization of the α-sialon phosphor particles used as the raw material and minimizes the contamination of impurities from the apparatus during mixing is preferred.

In step (2), the mixture of alumina powder and α-sialon phosphor powder is fired at 1300° C. or higher and 1700° C. or lower. In order to densify the composite, a higher firing temperature is preferable, but the above range is preferable because the higher the firing temperature, the lower the fluorescence properties of the α-sialon phosphor. The sintering method may be normal pressure sintering or pressure sintering. Sintering is preferred. Examples of pressure sintering methods include hot press sintering, spark plasma sintering (SPS), and hot isostatic pressure sintering (HIP). In the case of hot press sintering or SPS sintering, the pressure is preferably 10 MPa or higher, preferably 30 MPa or higher, and preferably 100 MPa or lower.
The firing atmosphere is preferably a non-oxidizing inert gas such as nitrogen or argon, or a vacuum atmosphere for the purpose of preventing oxidation of α-sialon.

The light emitting device of this embodiment will be described.

The light emitting device of the present embodiment includes a group III nitride semiconductor light emitting element (light emitting element 20) and the phosphor plate 10 provided on one surface of the group III nitride semiconductor light emitting element. A III-nitride semiconductor light-emitting device includes, for example, an n-layer, a light-emitting layer, and a p-layer, which are composed of III-nitride semiconductors such as AlGaN, GaN, and InAlGaN-based materials. A blue LED that emits blue light can be used as the Group III nitride semiconductor light-emitting device.
The phosphor plate 10 may be placed directly on one surface of the light emitting element 20, or may be placed via a light transmissive member or spacer.

The disc-shaped phosphor plate 100 (phosphor wafer) shown in FIG. 1 may be used as the phosphor plate 10 arranged on the light emitting element 20. can be used.
FIG. 1 is a schematic diagram showing an example of the configuration of a phosphor plate. The thickness of the phosphor plate 100 shown in FIG. 1 may be, for example, 100 μm or more and 1 mm or less. The thickness of the phosphor plate 100 can be appropriately adjusted by grinding or the like after it is obtained in the manufacturing process described above.
Note that the disk-shaped phosphor plate 100 is less likely to be chipped or cracked at its corners compared to the square-shaped phosphor plate 100, and is therefore excellent in durability and transportability.

An example of the above semiconductor device is shown in FIGS. 2A is a cross-sectional view schematically showing the configuration of a flip chip type light emitting device 110, and FIG. 2B is a cross sectional view schematically showing the configuration of a wire bonding type light emitting device 120. FIG.

A light-emitting device 110 of FIG. 2A includes a substrate 30, a light-emitting element 20 electrically connected to the substrate 30 via solder 40 (die bonding material), and a phosphor provided on the light-emitting surface of the light-emitting element 20. a body plate 10; The flip-chip type light emitting device 110 may have either a face-up type structure or a face-down type structure.
2B includes a substrate 30, a light emitting element 20 electrically connected to the substrate 30 via a bonding wire 60 and an electrode 50, and a light emitting surface provided on the light emitting element 20. and a phosphor plate 10 .
In FIG. 2, the light-emitting element 20 and the phosphor plate 10 are attached by a known method, and may be attached by a method such as a silicone-based adhesive or heat-sealing, for example.
Moreover, the light emitting device 110 and the light emitting device 120 may be entirely sealed with a transparent sealing material.

Alternatively, individualized phosphor plates 10 may be attached to the light emitting elements 20 mounted on the substrate 30 . A plurality of light-emitting elements 20 may be attached to a large-area phosphor plate 100 and then diced to separate the phosphor-plate 10-attached light-emitting elements 20 . Alternatively, a large-area phosphor plate 100 may be attached to a semiconductor wafer having a plurality of light-emitting elements 20 formed thereon, and then the semiconductor wafer and phosphor plate 100 may be singulated together.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than those described above can also be adopted.
1. A phosphor plate comprising a composite containing an α-sialon phosphor and a sintered body containing alumina.
2. 1. The phosphor plate according to
A phosphor plate having a thermal conductivity of 10 W/m·K or more and 40 W/m·K or less.
3. 1. or 2. The phosphor plate according to
The phosphor plate, wherein the content of the α-sialon phosphor is 5 Vol % or more and 50 Vol % or less in terms of volume with respect to the entire composite.
4. 1. ~3. The phosphor plate according to any one of
The phosphor plate, wherein the total content of the α-SiAlON phosphor and the alumina is 95 Vol % or more and 100 Vol % or less in terms of volume of the entire composite.
5. 1. ~ 4. The phosphor plate according to any one of
A phosphor plate, wherein the α-sialon phosphor contains an Eu element represented by the following general formula (1).
(M) _m(1-x)/p (Eu) _mx/2 (Si) _12-(m+n) (Al) _m+n (O) _n (N) _16-n General formula (1)
(In the above general formula (1), M represents one or more elements selected from the group consisting of Li, Mg, Ca, Y and lanthanide elements (excluding La and Ce), p represents the valence of the M element, 0<x<0.5, 1.5≦m≦4.0, and 0≦n≦2.0.)
6. 1. ~ 5. The phosphor plate according to any one of
The phosphor plate, wherein the alumina contains one or more selected from the group consisting of α-alumina and γ-alumina.
7. 1. ~6. The phosphor plate according to any one of
A phosphor plate, wherein an average particle diameter D50 of the α-sialon phosphor in the composite is 5 μm or more and 30 μm or less.
8. 1. ~7. The phosphor plate according to any one of
A phosphor plate having a surface roughness Ra of 0.1 μm or more and 2.0 μm or less on the main surface of the phosphor plate.
9. 1. ~8. The phosphor plate according to any one of
A phosphor plate used as a wavelength converter that converts irradiated blue light into orange light and emits light.
10. 1. ~ 9. The phosphor plate according to any one of
A phosphor plate having a light transmittance of 10% or less for blue light of 450 nm.
11. a group III nitride semiconductor light emitting device;
1. provided on one surface of the group III nitride semiconductor light emitting device; ~ 10. a phosphor plate according to any one of
A light emitting device.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to the description of these Examples.

(Example 1)
As raw materials for the phosphor plate of Example 1, alumina powder (TM-DAR, manufactured by Taimei Chemical Industry Co., Ltd.), Ca-α sialon phosphor (Aron Bright YL-600B, manufactured by Denka Co., Ltd., average particle size D50: 15 μm ) was used. 7.857 g of alumina powder and 2.833 g of Ca-α sialon phosphor powder were weighed and dry mixed in an agate mortar. The raw materials after mixing were passed through a nylon mesh sieve with an opening of 75 μm to deagglomerate to obtain raw material mixture powder. The compounding ratio calculated from the true density of the raw materials (alumina: 3.97 g/cm ³ , Ca-α sialon phosphor: 3.34 g/cm ³ ) is alumina: Ca-α sialon phosphor=70:30 by volume. %.

About 11 g of the mixed raw material powder was filled in a carbon die having an inner diameter of 30 mm in which a lower carbon punch was set, and an upper carbon punch was set to sandwich the raw material powder. A carbon sheet (GRAFOIL manufactured by GraTech) having a thickness of 0.127 mm was set between the mixed raw material powder and the carbon jig to prevent sticking.

The hot press jig filled with this raw material mixed powder was set in a multi-purpose high-temperature furnace (manufactured by Fuji Dempa Kogyo Co., Ltd., Hi-Multi 5000) of a carbon heater. The inside of the furnace was evacuated to 0.1 Pa or less, and the upper and lower punches were pressurized with a press pressure of 55 MPa while maintaining the reduced pressure state. The temperature was raised to 1600° C. at a rate of 5° C./min while maintaining the pressurized state. After reaching 1600° C., the heating was stopped, the temperature was slowly cooled to room temperature, and the pressure was released. After that, the fired product with an outer diameter of 30 mm was collected, and the outer peripheral portion was ground using a surface grinder and a cylindrical grinder to obtain a disc-shaped phosphor plate with a diameter of 25 mm and a thickness of 1.5 mm.
The bulk density of the phosphor plate of Example 1 was measured according to JIS-R1634:1998 and found to be 3.729 g/cm ³ . The relative density of the phosphor plate of Example 1 was 98.6%, since the theoretical density of the mixture calculated from the true density and compounding ratio of the raw materials was 3.781 g/cm ³ .
As a result of polishing the phosphor plate of Example 1 and performing SEM observation, it was observed that the Ca-α sialon phosphor particles were dispersed between the alumina matrix phases.
In addition, the surface roughness Ra of the main surface of the phosphor plate of Example 1 measured using a surface roughness measuring instrument (manufactured by Mitutoyo, SJ-400) in accordance with JIS B0601: 1994 is 1.0 μm, The surface roughness Ra of the back surface opposite to the main surface was 1.0 μm.

(Example 2)
As raw materials for the phosphor plate of Example 2, the same alumina powder and Ca-α sialon phosphor as in Example 1 were used. 6.701 g of alumina powder and 3.777 g of Ca-α sialon phosphor were weighed and dry mixed in an agate mortar. The compounding ratio calculated from the true density of the raw materials is alumina:Ca-α sialon phosphor=60:40% by volume.
The method for producing the phosphor plate of Example 2 is the same as the method for producing the phosphor plate of Example 1, except that the mixing ratio of the alumina powder and the Ca-α sialon phosphor is different.
As a result of measuring the bulk density of the phosphor plate of Example 2 in the same manner as in Example 1, it was 3.665 g/cm ³ . Since the raw material mixture has a theoretical density of 3.717 g/cm ³ , the relative density of the phosphor plate of Example 2 was 98.6%.
The surface roughness Ra of the main surface of the phosphor plate of Example 2 was 1.0 μm, and the surface roughness Ra of the back surface opposite to the main surface was 1.1 μm.

(Comparative example 1)
As raw materials for the phosphor plate of Comparative Example 1, SiO ₂ powder (FB-9DC grade, manufactured by Denka Co., Ltd.) and Ca-α sialon phosphor (Aron Bright YL-600B, manufactured by Denka Co., Ltd.) were used. 4.354 g of SiO ₂ powder and 2.723 g of Ca-α sialon phosphor powder were weighed and dry mixed in an agate mortar. The raw materials after mixing were passed through a nylon mesh sieve with an opening of 75 μm to obtain a raw material mixed powder. The compounding ratio calculated from the true density of the raw materials is SiO ₂ :Ca-α sialon phosphor=70:30% by volume.
About 7 g of the mixed raw material powder was filled in a carbon die for hot press in the same manner as in Example 1, and hot press sintered in a multi-purpose high-temperature furnace. The furnace is evacuated to 0.1 Pa or less, the temperature is raised from room temperature at a rate of 20 ° C. per minute while maintaining the reduced pressure, nitrogen gas is introduced into the furnace at 800 ° C., and the atmosphere pressure in the furnace is reduced to 0. .1 MPa·G. After introducing the nitrogen gas, the temperature was raised to 1375° C. at a rate of 5° C./min and held at 1375° C. for 15 minutes. After that, the temperature was lowered to room temperature at a rate of 5 ° C. per minute and the pressure was removed. A shaped phosphor plate was obtained.

[Thermal conductivity measurement]
The thermal conductivity of the phosphor plates of Examples 1 and 2 and Comparative Example 1 at room temperature (25° C.) was measured according to JIS1611:2010 by the flash method.
Thermal diffusivity: Measured using a xenon flash analyzer (LFA447, manufactured by Netch Japan Co., Ltd.).
- Specific heat capacity: determined using a DSC measuring device (DSC8000, manufactured by PerkinElmer) in accordance with JIS K7123.
Bulk density: Measured by a method in accordance with JIS-R1634:1998.
Thermal conductivity (W/m·K) = bulk density (g/cm ³ ) x thermal diffusivity (m ² /s) x specific heat capacity (J/(kg·K))
The thermal conductivity of the phosphor plate of Example 1 is 18 W/m·K, the thermal conductivity of the phosphor plate of Example 2 is 15 W/m·K, and the thermal conductivity of the phosphor plate of Comparative Example 1 is 1.5 W/m·K. It was 9 W/m·K.

[Crystal structure analysis]
The phosphor plates of Examples 1 and 2 were pulverized in a mortar to prepare powdery samples, and the diffraction patterns of the obtained samples were measured using an X-ray diffractometer (product name: UltimaIV, manufactured by Rigaku). As a result, it was confirmed that a crystal phase was present in the alumina sintered body. It was found that this crystal phase contained α-alumina as the main phase, and was slightly mixed with γ-alumina.

[Evaluation of optical properties]
The optical properties of the phosphor plate were measured using a chip-on-board type (COB type) LED package 130 . FIG. 3 is a schematic diagram of an apparatus (LED package 130) for measuring the emission spectrum of the phosphor plate 100. As shown in FIG.
First, the disc-shaped phosphor plate 100 having a thickness of 1.5 mm was thinned to 0.25 mm.
Next, an aluminum substrate (substrate 30) having recesses 70 was prepared. The diameter φ of the bottom surface of the recess 70 was set to 13.5 mm, and the diameter φ of the opening of the recess 70 was set to 16 mm. A blue LED (light emitting element 20 ) was mounted as a blue light source inside the concave portion 70 of the substrate 30 .
After that, a circular phosphor plate 100 is placed on top of the blue LED so as to block the opening of the recess 70 of the substrate 30, and the device shown in FIG. 3 (chip-on-board type (COB type) LED package 130) was made.

Using a total luminous flux measurement system (HalfMoon/φ1000 mm integrating sphere system, manufactured by Otsuka Electronics Co., Ltd.), the emission spectrum on the surface of the phosphor plate 100 was measured when the blue LED of the fabricated LED package 130 was turned on. The measurement results are shown in FIG.

FIG. 4 shows emission spectra when the phosphor plates of Examples 1 and 2 and Comparative Example 1 are used. The emission intensity on the vertical axis in FIG. 4 is a relative value when the maximum emission intensity of Example 1 is set to 100. As shown in FIG. In the emission spectrum, the maximum value of the emission intensity of orange light (Orange) having a wavelength of 595 nm or more and 605 nm is T _O , and the maximum value of the emission intensity of blue light (Blue) having a wavelength of 445 nm or more and 465 nm is T _B. , the amount of blue light transmitted from the blue LED was defined as T _B /T _O .

As shown in FIG. 4, the peak wavelength of the emission spectra of Examples 1 and 2 and Comparative Example 1 was about 600 nm. However, it was found that the emission intensity at the peak wavelength in Examples 1 and 2 showed a higher value than in Comparative Example 1.
Moreover, in both Examples 1 and 2 and Comparative Example 1, a slight spectrum derived from the transmitted light of the blue LED was observed near a wavelength of 450 nm. However, it was found that the blue light transmittances T _B /T _O from the blue LEDs in Examples 1 and 2 were comparable to those in Comparative Example 1.
In the phosphor plate of Example 1, the transmittance of blue light at a wavelength of 450 nm was 1.5%, indicating that the transmission of blue light was sufficiently suppressed.
It was found that by using the phosphor plates of Examples 1 and 2, it is possible to realize a light-emitting device with excellent fluorescence intensity of orange light and excellent luminous efficiency for converting blue light into orange light.

This application claims priority based on Japanese Patent Application No. 2018-189141 filed on October 4, 2018, and the entire disclosure thereof is incorporated herein.

Claims (8)

A method for producing a phosphor plate comprising a composite containing an α-sialon phosphor and a sintered body containing alumina, comprising:
A firing step of heating a raw material mixed powder of alumina powder and α-sialon phosphor powder at 1300° C. or higher and 1700° C. or lower to obtain the composite,
The thermal conductivity of the phosphor plate is 10 W/m K or more and 40 W/m K or less.
A method for manufacturing a phosphor plate. A method for manufacturing the phosphor plate according to claim 1,
The method for manufacturing a phosphor plate, wherein the content of the α-SiAlON phosphor is 5 Vol % or more and 50 Vol % or less in terms of volume with respect to the entire composite. A method for manufacturing a phosphor plate according to claim 1 or 2,
The method for producing a phosphor plate, wherein the total content of the α-sialon phosphor and the alumina is 95 Vol % or more and 100 Vol % or less in terms of volume of the entire composite. A method for manufacturing a phosphor plate according to any one of claims 1 to 3,
A method for manufacturing a phosphor plate, wherein the α-sialon phosphor contains an Eu element-containing α-sialon phosphor represented by the following general formula (1).
(M) _m(1-x)/p (Eu) _mx/2 (Si) _12-(m+n) (Al) _m+n (O) _n (N) _16-n General formula (1)
(In the above general formula (1), M represents one or more elements selected from the group consisting of Li, Mg, Ca, Y and lanthanide elements (excluding La and Ce), p represents the valence of the M element, 0<x<0.5, 1.5≦m≦4.0, and 0≦n≦2.0.) A method for manufacturing a phosphor plate according to any one of claims 1 to 4,
A method for producing a phosphor plate, wherein the alumina contains at least one selected from the group consisting of α-alumina and γ-alumina. A method for manufacturing a phosphor plate according to any one of claims 1 to 5,
A method for producing a phosphor plate, wherein the α-sialon phosphor in the composite has an average particle diameter D50 of 5 μm or more and 30 μm or less. A method for manufacturing a phosphor plate according to any one of claims 1 to 6,
A method for manufacturing a phosphor plate, wherein the main surface of the phosphor plate has a surface roughness Ra of 0.1 μm or more and 2.0 μm or less. A method for manufacturing a phosphor plate according to any one of claims 1 to 7,
A method for producing a phosphor plate having a light transmittance of 10% or less for blue light of 450 nm.

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