Alpha-sialon phosphor powder, wavelength conversion member, and light-emitting device

Abstract

An alpha-type sialon phosphor powder in which the average circularity of alpha-type sialon phosphor particles having a circle-equivalent diameter of 3-80 [mu] m in the alpha-type sialon phosphor powder is 0.85-0.95, and the average aspect ratio of the alpha-type sialon phosphor particles having a circle-equivalent diameter of 3-80 [mu] m in the alpha-type sialon phosphor powder is 0.65-0.85.

Description

TECHNICAL FIELD

[0001] Sialon phosphor of α type is widely researched as a material for constituting a wavelength conversion member for converting blue light into light of a lower wavelength in an LED (Light Emitting Diode) package.

[0002] In Patent Literature 1, a Sialon of α type represented by a specific general formula is described. The Sialon of α type has an oxygen content of 1.2 mass% or less. Primary particles constituting the Sialon of α type are columnarized. In a case where ultraviolet rays or visible light having a wavelength of 250 to 500 nm is irradiated as an excitation source to the Sialon of α type, a fluorescent property having a peak in a wavelength region in a range of 595 to 630 nm is exhibited.

[0003] In Patent Literature 2, a phosphor capable of providing a white LED excellent in luminous efficiency with a blue LED or an ultraviolet LED as a light source is described. The phosphor is constituted of a Sialon of α type represented by a general formula: (M1) x (M2) y (Si, Al) 12 (O, N) 16 (wherein M1 is one or more elements selected from the group consisting of Li, Mg, Ca, Y, and lanthanoid elements (except La and Ce), M2 is one or more elements selected from the group consisting of Ce, Pr, Eu, Tb, Yb, and Er, 0.3 ≤ X + Y ≤ 1.5 and 0 < Y ≤ 0.7) as a main component, and is constituted of a powder having a specific surface area of 0.2 to 0.5 m 2 / g.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: International Publication No. 2010 / 087348

[0007] Patent Literature 2: International Publication No. 2007 / 129713 SUMMARY

[0008] In constituting a wavelength conversion member in an LED package, generally, a Sialon phosphor of α type is mixed with a curable resin material (sealing material). Therefore, it is preferable that not only the performance of the Sialon phosphor of α type itself but also the Sialon phosphor of α type together with the curable resin material (sealing material) as a wavelength conversion member, and a good light emitting property is obtained as an LED package.

[0009] Incidentally, the present inventors found through preliminary studies that even when an α-sialon phosphor having good luminescent properties (quantum yield, etc.) is used in powder evaluation, the luminescent performance of an LED package is not always improved as expected. And, from this insight, even when an α-sialon phosphor having not-so-good luminescent properties (quantum yield, etc.) is used in powder evaluation, the luminescent performance of an LED package can unexpectedly be good.

[0010] The present application was completed in view of this situation. One of the objects of the present application is to provide an α-sialon phosphor that can preferably be used for the manufacture of an LED package.

[0011] The present inventors completed the application provided below, which solves the above problems. 1.

[0013] An α-sialon phosphor powder, wherein,

[0014] The average of the equivalent circular diameters of the α-sialon phosphor particles having an equivalent circular diameter of 3 to 80 μm in the α-sialon phosphor powder is 15 to 35 μm.

[0015] The average circularity of the α-sialon phosphor particles having an equivalent circular diameter of 3 to 80 μm in the α-sialon phosphor powder is 0.85 to 0.95,

[0016] The average of the aspect ratios of the α-sialon phosphor particles having an equivalent circular diameter of 3 to 80 μm in the α-sialon phosphor powder is 0.65 to 0.85. 2.

[0018] The α-sialon phosphor powder according to 1, wherein,

[0019] The average of the equivalent circular diameters of the α-sialon phosphor particles having an equivalent circular diameter of 3 to 80 μm in the α-sialon phosphor powder is 15 to 35 μm. 3.

[0021] The α-sialon phosphor powder according to 1 or 2, wherein,

[0022] The average circularity of the α-sialon phosphor particles having an equivalent circular diameter of 20 to 60 μm in the α-sialon phosphor powder is 0.80 to 0.90. 4.

[0024] The α-sialon phosphor powder according to any one of 1 to 3, wherein,

[0025] The average of the aspect ratios of the α-sialon phosphor particles having an equivalent circular diameter of 20 to 60 μm in the α-sialon phosphor powder is 0.70 to 0.80. 5.

[0027] The α-sialon phosphor powder according to any one of 1. to 4., wherein

[0028] The average value of the equivalent circle diameters of the α-sialon phosphor particles having an equivalent circle diameter of 20 to 60 μm in the α-sialon phosphor powder is 25 to 35 μm. 6.

[0030] The α-sialon phosphor powder according to any one of 1. to 5., wherein

[0031] The cumulative 50% particle diameter D50 on a volume basis, which is obtained by a laser diffraction / scattering method 50 is 20 to 40 μm. 7.

[0033] The α-sialon phosphor powder according to any one of 1. to 6., wherein

[0034] The cumulative 10% particle diameter D10 on a volume basis, which is obtained by a laser diffraction / scattering method, is set as D 10 , the cumulative 50% particle diameter D50 on a volume basis is set as D 50 , and the cumulative 90% particle diameter D90 on a volume basis is set as D 90 , the value of (D 90 -D 10 ) / D 50 is 1.05 to 1.5. 8.

[0036] A wavelength conversion member in which the α-sialon phosphor powder according to any one of 1. to 7. is dispersed in a sealing material. 9.

[0038] A light emitting device provided with the wavelength conversion member according to 8. and a light emitting element capable of irradiating the wavelength conversion member with excitation light.

[0039] According to the present application, an α-sialon phosphor that can be preferably used for the manufacture of an LED package is provided. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a schematic cross-sectional view showing one example of the structure of a light emitting device (specifically, an LED package). DETAILED DESCRIPTION

[0041] Hereinafter, embodiments of the present application will be described in detail with reference to the drawings.

[0042] In the drawings, the same symbols are attached to the same constituent elements, and the description will be appropriately omitted.

[0043] In order to avoid complication, in the case where a plurality of the same components exist within the same drawing, sometimes only one of them is labeled with a symbol, instead of all of them.

[0044] The drawings are merely schematic and are not necessarily drawn to scale. Particular dimensions, shapes or the like of the components in the drawings are not necessarily corresponding to those of the actual articles.

[0045] In the present specification, the expression "X to Y" in the description of a numerical range means X or more and Y or less, unless otherwise specified. For example, "1 to 5 mass%" means "1 mass% or more and 5 mass% or less".

[0046] In the present specification, the aspect ratio of a particle is defined by (short diameter / long diameter) in a two-dimensional image of the particle. That is, in the present specification, the aspect ratio of a particle is greater than 0 and 1 or less.

[0047] <α-type sialon phosphor powder>

[0048] The average circularity of the α-type sialon phosphor particles having an equivalent circle diameter of 3 to 80 μm in the α-type sialon phosphor powder of the present embodiment is 0.85 to 0.95, and preferably 0.86 to 0.92. Also, the average value of the aspect ratio (short diameter / long diameter) of the α-type sialon phosphor particles having an equivalent circle diameter of 3 to 80 μm in the α-type sialon phosphor powder of the present embodiment is 0.65 to 0.85, and preferably 0.70 to 0.80.

[0049] Most of the particles in the conventional α-type sialon phosphor powder are columnar, that is, elongated in shape.

[0050] In contrast, the average circularity of the particles in the α-type sialon phosphor powder of the present embodiment is somewhat large, and the aspect ratio (short diameter / long diameter) is not an extremely small value, and thus it can be said that the shape is moderately round (at least, compared to the particles in the conventional α-type sialon phosphor powder, it is not elongated).

[0051] In the wavelength conversion member in the LED package, the α-type sialon phosphor particles are dispersed in the sealing material. The details are not clear, but for example, as described above, by the particles being moderately round in shape, the dispersibility of the particles in the sealing material is improved, and as a result, it is possible to improve the characteristics as a wavelength conversion member.

[0052] Also, it is considered that, compared to the case where columnar particles are dispersed in the sealing material, the case where the particles moderately round in shape are dispersed in the sealing material more easily allows the excitation light to enter the inside of the wavelength conversion member, and thus improves the characteristics as a wavelength conversion member.

[0053] Further, the fact that the particles are in a moderately circular shape means that the particles have a small anisotropy. It is believed that because the particles have a small anisotropy, the fluorescence (luminescence) can be obtained with a relatively constant efficiency regardless of the direction (angle of incidence) of the excitation light that is incident on the wavelength conversion member. It is also believed that this results in an increase in the brightness of the LED package.

[0054] As a matter of precaution, the average circularity and the average aspect ratio of the "α-sialon phosphor particles having an equivalent circle diameter of 3 to 80 μm" in the α-sialon phosphor powder were used as indices based on the following reasons and the like: (i) α-sialon phosphor particles having an equivalent circle diameter of less than 3 μm are too small to properly measure the average circularity or the aspect ratio; and (ii) in the case of coarse particles having an equivalent circle diameter of more than 80 μm, the light emission characteristics based on the shape are not easily varied due to the size.

[0055] The α-sialon phosphor powder of the present embodiment can be produced by using appropriate raw materials and by performing appropriate manufacturing processes. Specifically, it is possible to cite the use of silicon nitride in which β-silicon nitride is the main component as a raw material, the use of core particles that can become the starting point of crystal growth, and the like. The raw materials or the manufacturing method will be described in detail later.

[0056] In the case where appropriate raw materials and manufacturing processes are not selected, it can not be possible to produce the α-sialon phosphor powder of the present embodiment.

[0057] Incidentally, the circularity or the aspect ratio of the particles in the α-sialon phosphor powder can be measured using a flow-type particle image analyzer.

[0058] The description of the α-sialon phosphor powder of the present embodiment will be continued.

[0059] [average value of the equivalent circle diameters of the particles having an equivalent circle diameter of 3 to 80 μm]

[0060] The average value of the equivalent circle diameters of the α-sialon phosphor particles having an equivalent circle diameter of 3 to 80 μm in the α-sialon phosphor powder of the present embodiment is preferably 15 to 35 μm, more preferably 15 to 30 μm, and further preferably 15 to 25 μm. Although it is a presumption, by this value being appropriate, the phosphor particles are more appropriately dispersed in the sealing material, and it can be possible to further improve the light emission performance of the LED package.

[0061] [various numerical values of the particles having an equivalent circle diameter of 20 to 60 μm]

[0062] Thus far, the average circularity, the average aspect ratio, and the average value of the equivalent circle diameters of the "α-sialon phosphor particles having an equivalent circle diameter of 3 to 80 μm" in the α-sialon phosphor powder have been described.

[0063] Further, by appropriately adjusting the average circularity, the average of the aspect ratio, and the average of the equivalent circle diameter of the "α-sialon phosphor particles having an equivalent circle diameter of 20 to 60 μm" in the α-sialon phosphor powder, the light emitting performance of the LED package can be further improved.

[0064] The equivalent circle diameter of the α-sialon phosphor particles having an equivalent circle diameter of 20 to 60 μm is not too large nor too small, and thus the light emitting characteristics are basically good compared to fine particles or coarse particles. By appropriately adjusting the average circularity, the average of the aspect ratio, and the average of the equivalent circle diameter of such α-sialon phosphor particles, the light emitting performance of the LED package can be further improved.

[0065] Specifically, the average circularity of the α-sialon phosphor particles having an equivalent circle diameter of 20 to 60 μm in the α-sialon phosphor powder of the present embodiment is preferably 0.80 to 0.90, more preferably 0.82 to 0.89.

[0066] Further, the average of the aspect ratio of the α-sialon phosphor particles having an equivalent circle diameter of 20 to 60 μm in the α-sialon phosphor powder of the present embodiment is preferably 0.70 to 0.80, more preferably 0.72 to 0.77.

[0067] Further, the average of the equivalent circle diameter of the α-sialon phosphor particles having an equivalent circle diameter of 20 to 60 μm in the α-sialon phosphor powder of the present embodiment is preferably 25 to 35 μm, more preferably 28 to 35 μm, further preferably 30 to 35 μm.

[0068] [About the particle size distribution obtained by the laser diffraction / scattering method]

[0069] In the present embodiment, in addition to adjusting the average of the circularity or the aspect ratio of the particles measured using the flow-type particle image analyzer, it is also preferable to adjust the particle size distribution of the α-sialon phosphor powder obtained by the laser diffraction / scattering method. The specific values are as follows.

[0070] The cumulative 50% diameter D 50 on a volume basis of the α-sialon phosphor powder of the present embodiment obtained by the laser diffraction / scattering method is preferably 20 to 40 μm, more preferably 23 to 40 μm, further preferably 25 to 35 μm.

[0071] The cumulative 90% diameter D 90 on a volume basis of the α-sialon phosphor powder of the present embodiment obtained by the laser diffraction / scattering method is preferably 40 to 70 μm, more preferably 42 to 60 μm.

[0072] The cumulative 10% diameter D of the α-sialon phosphor powder of the present embodiment, measured by the laser diffraction / scattering method, on a volume basis 10 Preferably, it is 20 to 40 μm, preferably 10 to 25 μm, and more preferably 12 to 20 μm. In particular, from the viewpoint of reducing phosphor particles (fines) that tend to deteriorate the luminous efficiency, D 10 Preferably, it is a value that is not too large.

[0073] The cumulative 97% diameter D of the α-sialon phosphor powder of the present embodiment, measured by the laser diffraction / scattering method, on a volume basis 97 Preferably, it is 60 to 100 μm, and more preferably 65 to 90 μm. Also, the cumulative 100% diameter D of the α-sialon phosphor obtained 100 Preferably, it is 100 to 200 μm, and more preferably 110 to 190 μm. With respect to excessively coarse phosphor particles, excitation light does not reach the inside of the particles, and thus there is a tendency for the luminous efficiency per unit mass or per unit volume to decrease. Therefore, D 97 or D 100 Preferably, it is not too large.

[0074] The particle size distribution of the α-sialon phosphor powder of the present embodiment is preferably sharp. By sharp particle size distribution, it is meant that the phosphor particles in the phosphor powder are at least homogeneous in terms of particle size. Also, this is expected to result in stable light emission, or to reduce variations in the light emission characteristics between product lots.

[0075] As an index of the sharpness of the particle size distribution, the value of the index: (D 10 , D 50 , and D 90 (D 90 -D 10 ) / D 50 ) is set as a quantitative index. The value of (D 90 -D 10 ) / D 50 is preferably 1.05 to 1.6, more preferably 1.05 to 1.5, and further preferably 1.1 to 1.4.

[0076] Also, from the viewpoint of reducing the aforementioned particles (fines) that are extremely small in particle size, the value of (D 50 -D 10 ) / D 50 is also a good index. The value of (D 50 -D 10 ) / D 50 is preferably 0.40 to 0.60, more preferably 0.40 to 0.55, and further preferably 0.43 to 0.49.

[0077] [Elemental Composition]

[0078] The α-type sialon phosphor powder of the present embodiment preferably contains calcium. That is, the α-type sialon phosphor powder of the present embodiment is preferably composed of so-called calcium-α-type sialon.

[0079] The composition formula of the α-type sialon phosphor powder of the present embodiment is, for example, (Ca x , Eu y ) m / 2 Si 12-(m+n) Al m+ n O n N 16-n (m = 2(x + y)) is represented. Here, m is preferably 3.0 to 4.0, x is preferably 1.2 to 1.7, y is preferably 0.04 to 0.10, and n is preferably 0 to 0.5.

[0080] [Manufacturing method]

[0081] As described above, the α-type sialon phosphor of the present embodiment can be manufactured by using appropriate raw materials and going through appropriate manufacturing processes. The following will be described in detail.

[0082] The α-type sialon phosphor of the present embodiment is preferably manufactured by including the following series of processes:

[0083] A mixture preparation process of preparing a mixture containing silicon nitride, an aluminum source, a calcium source, and an europium source;

[0084] A firing process of firing the above mixture to obtain a fired product.

[0085] Here, as the silicon nitride in the mixture preparation process (i.e., the silicon nitride as a raw material), silicon nitride rich in β-type silicon nitride is preferably used. Specifically, for example, more than 50 mass% of the silicon nitride in the mixture preparation process is β-type silicon nitride, preferably more than 80 mass%, further preferably more than 90 mass%, particularly preferably more than 95 mass%, and especially preferably more than 98 mass%.

[0086] As the silicon nitride, silicon nitride having an oxygen content of 0.5 mass% or less is preferably used. The oxygen content of the silicon nitride is more preferably 0.3 mass% or less, and further preferably 0.2 mass% or less. The lower limit of the oxygen content is preferably zero (below the detection limit), but in practice, it is 0.05 mass% or more.

[0087] Although the details are not clear, by containing a large amount of β-type silicon nitride and preferably using silicon nitride having a small oxygen content as a raw material, it is easy to manufacture α-type sialon phosphor powder having the average circularity or the average value of the aspect ratio described above.

[0088] As the silicon nitride rich in β-type silicon nitride, a commercially available product can be used. Also, the ratio of β-type silicon nitride can be increased by purchasing a commercially available silicon nitride (the content of β-type silicon nitride is not limited) and performing a heat treatment.

[0089] As described above, as the silicon nitride, it is preferable to use a silicon nitride having an oxygen content of 0.5 mass% or less. In order to use such a silicon nitride having a small oxygen content, a commercially available silicon nitride having a small oxygen content can be selected for use, or a commercially available silicon nitride can be heated as described above to increase the ratio of β-type silicon nitride while reducing the oxygen content. The heating conditions at this time can be set to 1950 to 2050°C and 1 to 15 hours, for example, in a nitrogen atmosphere.

[0090] Although the details are not clear, by using a silicon nitride having a small oxygen content, an α-sialon phosphor that is further preferably suitable for an LED package can be obtained.

[0091] [Preparation of mixture]

[0092] In the preparation of the mixture, a mixture containing a silicon nitride rich in β-type silicon nitride, an aluminum source, a calcium source, and an europium source is preferably prepared. Incidentally, if the calcium source is used, the α-sialon phosphor obtained becomes a so-called calcium-α-sialon.

[0093] The aluminum source preferably contains aluminum nitride or aluminum oxide.

[0094] The calcium source preferably contains calcium nitride, calcium oxide, or calcium carbonate.

[0095] As the europium source, for example, an oxide containing europium, a hydroxide containing europium, a nitride containing europium, an oxynitride containing europium, a halide containing europium, or the like can be given.

[0096] These aluminum source, calcium source, and europium source can be used individually or in combination with two or more. Among them, the europium source preferably contains europium oxide or europium nitride.

[0097] The mixing ratio of each raw material can be appropriately determined based on the manufacturing method of the α-sialon phosphor of the present embodiment, the general formula of the α-sialon phosphor, and the like. The general formula is as described above. To be on the safe side, the composition of the α-sialon phosphor finally obtained is not limited to a substance that satisfies the aforementioned general formula.

[0098] The mixture preferably contains a core particle of an α-sialon phosphor in addition to the silicon nitride rich in β-type silicon nitride, the aluminum source, the calcium source, and the europium source. The core particle refers to a particle of an α-sialon phosphor that is manufactured in advance. In the case where the core particle is used, the amount thereof is 3 to 20 mass%, more preferably 5 to 15 mass%, for example, in the entire mixture.

[0099] Although the details are not clear, it is considered that by using the core particles, crystallization is performed from the core particles as a starting point in the subsequent sintering process. It is considered that this is related to the production of phosphor powders having an average circularity or an average value of an aspect ratio as desired. Then, it is considered that as a result thereof, phosphor particles having particularly good light emission properties when used in LED packages can be produced.

[0100] The core particles can generally be obtained by going through substantially the same processes as the production method of the phosphor powder shown here. For example, they can be obtained by going through the following (1) and (2). However, when obtaining the core particles, it is preferable to use a silicon nitride powder rich in β-type silicon nitride as a raw material, but a silicon nitride powder rich in α-type silicon nitride can sometimes be used.

[0101] (1) The [mixture preparation process], [sintering process], and [pulverization process] described in this specification are performed except that no core particles are used, and α-sialon phosphor particles are obtained.

[0102] (2) The α-sialon phosphor particles obtained in the above (1) are used as pseudo core particles, the [mixture preparation process], [sintering process], and [pulverization process] described in this specification are performed, and α-sialon phosphor particles are obtained. The particles are used as core particles.

[0103] In order to improve the uniformity of the core particles and the like, the α-sialon phosphor particles obtained in (2) can be further subjected to the process of (2) once or several times as temporary core particles to obtain core particles.

[0104] As a method of mixing the raw materials, there are a method of performing dry mixing, and a method of performing wet mixing in a non-reactive solvent in which the respective components of the raw materials do not substantially react, and then removing the solvent. As a mixing device, there are a V-type mixer, a swing mixer, a ball mill, and a vibration mill. In the case of using a raw material that is unstable in the atmosphere, hydrolysis or oxidation of the raw material can affect the properties of the synthesized product, and thus it is preferable to perform it in a glove box in a non-reactive environment. Of course, a method or device other than those described here can also be used.

[0105] [Sintering process]

[0106] In the sintering process, the mixture obtained by mixing as described above is sintered to obtain a sintered product. The sintering process is preferably performed by adding the mixture into a container made of a material having low reactivity with the synthesized phosphor, such as a boron nitride container.

[0107] The sintering process is preferably performed in a non-reactive gas environment such as nitrogen. The pressure in the sintering process is preferably set to around 0.5 to 1 MPa G.

[0108] In the firing step, the mixture obtained in the mixture preparation step is preferably fired at 1800°C or higher, more preferably at 1800 to 2000°C, and further preferably at 1850 to 1950°C.

[0109] The time of the firing step, specifically, the time of heating the mixture at 1800°C or higher, is preferably 10 to 40 hours, and more preferably 15 to 30 hours.

[0110] [Crushing Step]

[0111] The crushing step is preferably performed after the firing step. In the crushing step, the fired product (typically, a block) obtained in the firing step is crushed by applying an appropriate external force to the fired product. The crushing can be performed using, for example, an air jet crusher. The crushing conditions can be set to, for example, 0.1 to 0.5 MPa.

[0112] [Reduction Annealing Step]

[0113] The fired product crushed in the crushing step is preferably subjected to annealing (heat treatment) in a reducing atmosphere. That is, in the production of the α-type sialon phosphor powder of the present embodiment, a reduction annealing step is preferably performed, in which the fired product obtained in the firing step (preferably, the fired product after being crushed) is heated in a reducing atmosphere.

[0114] The reduction annealing step is preferably a step in which the fired product is heated in an atmosphere containing hydrogen. More preferably, the reduction annealing step is a step in which the fired product is heated in an atmosphere containing 50 vol% or more of hydrogen. Further preferably, the reduction annealing step is a step in which the fired product is heated in an atmosphere containing 80 vol% or more of hydrogen. Particularly preferably, the reduction annealing step is a step in which the fired product is heated in an atmosphere consisting essentially of hydrogen.

[0115] The reduction annealing step is preferably performed after lithium oxide (Li20) is added to the fired product. Although the details are not clear, by so doing, an α-type sialon phosphor more suitable for application to an LED package can be produced. Although the details are not clear, one of the hypotheses is that the lithium oxide (Li20) can remove impurities that do not contribute to fluorescence. Also, it is possible that the Eu 3+ is reduced to Eu 2+ and the performance of the α-type sialon phosphor is improved.

[0116] In the reduction annealing step, the fired product is preferably heated to 1300 to 1500°C, more preferably to 1350 to 1450°C. Also, the heating time (the time during which the fired product is heated to 1300 to 1500°C) is preferably 3 to 20 hours, more preferably 5 to 15 hours. Also, the pressure is preferably 0.01 to 0.1 MPa-G, more preferably 0.01 to 0.05 MPa-G.

[0117] The heating temperature, the heating time, and the pressure are appropriately determined from the viewpoint of performing sufficient reduction and the viewpoint of saving energy costs.

[0118] [Acid treatment step]

[0119] The phosphor after the above reduction annealing step is preferably immersed in an aqueous acid solution and appropriately stirred. By this means, foreign matter on the surface of the phosphor or a heterogeneous phase that does not contribute to fluorescence is sometimes removed.

[0120] As the aqueous acid solution, an aqueous solution containing one or more kinds of acid selected from the group consisting of hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid can be used. An aqueous mixed solution of hydrofluoric acid and nitric acid is particularly preferable.

[0121] The acid treatment can be performed by stirring the phosphor in the aqueous acid solution for several minutes to several hours (for example, 10 minutes to 6 hours). A publicly known stirrer or the like can be used in the stirring. The temperature at the time of stirring is, for example, 50 to 100°C, and is preferably 65 to 85°C (the liquid is maintained at this temperature). The time of stirring is, for example, 1 minute to 2 hours, and is preferably about 10 minutes to 1 hour. The stirring speed is, for example, 300 to 600 rpm, and is preferably 400 to 500 rpm.

[0122] After this treatment, filtration, water washing, drying, and the like are preferably appropriately performed.

[0123] [Elutriation step]

[0124] In the production of α-type sialon phosphor, the elutriation step is preferably performed. By the elutriation step, super-fine phosphor particles having poor luminous efficiency are removed, and the luminous properties and the like of the final α-type sialon phosphor can be further improved. The specific method of elutriation can appropriately apply a publicly known method.

[0125] By the elutriation step, fine phosphor particles having a particle diameter of 7 μm or less are preferably substantially removed, and fine phosphor particles having a particle diameter of 12 μm or less are more preferably substantially removed.

[0126] <Method for manufacturing wavelength conversion member and method for manufacturing light emitting device>

[0127] A wavelength conversion member can be manufactured by a series of processes including a dispersing process of preparing a dispersion by dispersing the α-sialon phosphor obtained by the above manufacturing method in a sealing material (resin material) and a curing process of curing the dispersion. Incidentally, the wavelength conversion member can be manufactured by mixing the phosphor and molten glass, and then curing while making it into a desired shape.

[0128] Then, the manufactured wavelength conversion member and the light emitting element can be combined to manufacture a light emitting device (LED package).

[0129] The wavelength conversion member can contain the α-sialon phosphor and a phosphor different therefrom (for example, CASN, SCASN, or the like as a red phosphor), and can not contain it. If the desired light emitting properties can be obtained by the α-sialon phosphor alone, a different phosphor can not be used.

[0130] The sealing material is generally a thermosetting resin material, and is preferably a silicone-based thermosetting material. The silicone-based thermosetting material is preferably used in view of heat resistance, light transmittance after curing, and the like. On the other hand, as described above, the wavelength conversion member can be manufactured by mixing molten glass and the phosphor using glass as a raw material.

[0131] The amount of the phosphor / the amount of the sealing material (resin material), that is, the amount ratio of the phosphor / sealing material at the time of manufacturing the wavelength conversion member is preferably adjusted to be between 0.2 and 0.7, and more preferably adjusted to be between 0.4 and 0.7 on a mass basis. The same applies to the amount of the phosphor / the amount of the glass when the glass is used as a raw material.

[0132] Figure 1 is a schematic cross-sectional view showing one example of the structure of a light emitting device. As shown in Figure 1 The light emitting device 100 is provided with a light emitting element 120, a heat sink 130, a case 140, a first lead frame 150, a second lead frame 160, a bonding wire 170, a bonding wire 172, and a composite body 40.

[0133] The light emitting element 120 is mounted on a prescribed region of the upper surface of the heat sink 130. By mounting the light emitting element 120 on the heat sink 130, the heat dissipation properties of the light emitting element 120 can be improved. In addition, a packaging substrate can be used instead of the heat sink 130.

[0134] The light emitting element 120 is a semiconductor element that emits excitation light. As the light emitting element 120, for example, an LED chip that generates light having a wavelength of 300 nm or more and 500 nm or less, which corresponds to near-ultraviolet to blue light, can be used. One electrode (not shown) provided on the upper surface side of the light emitting element 120 is connected to the surface of the first lead frame 150 via a bonding wire 170 such as a gold wire. Also, the other electrode (not shown) formed on the upper surface of the light emitting element 120 is connected to the surface of the second lead frame 160 via a bonding wire 172 such as a gold wire.

[0135] A recess having a substantially funnel shape in which the aperture diameter gradually increases from the bottom surface toward the upper side is formed in the housing 140. The light emitting element 120 is disposed on the bottom surface of the recess. The wall surface of the recess that surrounds the light emitting element 120 functions as a reflection plate.

[0136] The composite 40 is filled in the recess whose wall surface is formed by the housing 140. The composite 40 is a wavelength conversion member that converts the excitation light emitted from the light emitting element 120 into light having a longer wavelength. As the composite 40, the wavelength conversion member of the present embodiment described above is used. In the present embodiment, the composite 40 is formed by the phosphor particles 1 and the sealing material 30. Figure 1

[0137] Incidentally, in the present embodiment, a surface mounting type light emitting device is exemplified, but the light emitting device is not limited to the surface mounting type. The light emitting device can be a can type or a COB (Chip On Board) type, a CSP (Chip Scale Package) type, or the like. Figure 1

[0138] The above describes the embodiments of the present application, but these are merely examples of the present application, and various configurations other than the above can be employed. Also, the present application is not limited to the above-described embodiments, and modifications, and the like within the scope of achieving the objects of the present application are included in the present application.

[0139] Example

[0140] The embodiments of the present application are described in detail according to the examples and comparative examples. For the sake of safety, it is described that the present application is not limited to the examples.

[0141] Preparation of Raw Materials

[0142] The following raw materials were prepared.

[0143] • Silicon nitride powder (main component: β type): β type silicon nitride powder purchased from H. C. STARK Co. was heated under conditions of 2000°C, 3 hours, 0.85 MPa · G, and nitrogen atmosphere. The ratio of β type silicon nitride: 99 mass%, oxygen content: 0.12 mass%.

[0144] ​​• Silicon nitride powder (main component: α type): manufactured by UBE Corporation, E10 grade (ratio of α type silicon nitride: 98 mass%)

[0145] • Aluminum nitride powder: manufactured by Tokuyama Corporation, E grade

[0146] • Calcium nitride powder: manufactured by Kojundo Chemical Lab. Co., Ltd.

[0147] • Europium oxide powder: manufactured by NIPPON YTTRIUM CO., LTD.

[0148] • α-sialon core particles (for use in Examples): α-sialon particles manufactured in the following manner, D10 = 10.1 μm, D50 = 21.3 μm, D90 = 43.0 μm 10 = 10.1 μm, D 50 = 21.3 μm, D 90 = 43.0 μm

[0149] (1) Except that α-sialon core particles were not used, the [mixture preparation step], [firing step], and [pulverization step] in the following <Manufacture of α-sialon phosphor> were performed, and α-sialon particles were obtained (as the silicon nitride powder, (main component: α type) was used).

[0150] (2) The α-sialon particles obtained in the above (1) were used as the core particles, the [mixture preparation step], [firing step], and [pulverization step] in the following <Manufacture of α-sialon phosphor> were performed, and α-sialon particles were obtained (as the silicon nitride powder, (main component: β type) was used). The α-sialon particles thus obtained were used as the α-sialon core particles used in the Examples.

[0151] • α-sialon core particles (for use in Comparative Examples): α-sialon particles manufactured in the following manner, D10 = 7.2 μm, D50 = 16.7 μm, D90 = 33.9 μm

[0152] (1) Except that α-sialon core particles were not used, the [mixture preparation step], [firing step], and [pulverization step] in the following <Manufacture of α-sialon phosphor> were performed, and α-sialon particles were obtained (as the silicon nitride powder, (main component: α type) was used).

[0153] (2) The α-sialon particles obtained in the above (1) were used as the core particles, the [mixture preparation step], [firing step], and [pulverization step] in the following <Manufacture of α-sialon phosphor> were performed, and α-sialon particles were obtained (as the silicon nitride powder, (main component: α type) was used). The α-sialon particles thus obtained were used as the α-sialon core particles used in the Comparative Examples.

[0154] • Lithium oxide (Li20) used in the reduction annealing process: manufactured by Kojundo Chemical Lab. Co., Ltd.

[0155] In the above, an XRD diffraction pattern was obtained using an X-ray diffraction measuring device "D8" manufactured by Bruker, and the pattern was subjected to renormalization analysis using analysis software "TOPAS", whereby the ratio of α / β silicon nitride in the silicon nitride powder was found.

[0156] Further, the oxygen content in the silicon nitride powder was measured by EMGA-920 manufactured by HORIBA.

[0157] <Manufacture of α-sialon phosphor>

[0158] [Preparation of mixture]

[0159] The above-mentioned silicon nitride powder (main component: β type in the examples, main component: α type in the comparative examples) 138.22 g, aluminum nitride powder 46.92 g, europium oxide powder 3.60 g, calcium nitride powder 27.26 g, and α-sialon core particles (the above-mentioned (for the examples) or (for the comparative examples)) 24.00 g were thoroughly mixed. Thereby, a mixture was obtained.

[0160] (The mixing ratio of the above-mentioned raw materials is ideally (Ca x , Eu y ) m / 2Si 12-(m+n) Al m+n O n N 16-n (m = 3.35, x = 1.62, y = 0.06, n = 0 (not considering the oxygen content)) in the general formula of (Ca

[0161] Supplementary note that, in Examples 1 to 3, the mixtures are the same, and in Comparative Examples 1 and 2, the mixtures are the same, and in Comparative Examples 3 and 4, the mixtures are the same.

[0162] [Calcination process]

[0163] Each of the mixtures obtained was added to a boron nitride-made container (manufactured by Denka Company Limited), and calcination was performed under the conditions described in the table below in a nitrogen atmosphere.

[0164] [Crushing process]

[0165] The calcination product obtained in the calcination process was crushed using an air jet crusher under the conditions of 0.30 MPa, 40 g / min.

[0166] [Reduction annealing process]

[0167] The calcined product subjected to the pulverization process was annealed under an environment consisting essentially of hydrogen at 1425°C for 8h at 0.03 MPa G.

[0168] In some examples and comparative examples, 0.25 mass% of Li20 was added to the calcined product and mixed well before annealing.

[0169] [Acid treatment process]

[0170] The calcined product subjected to the reduction annealing process was put into a mixed aqueous solution of hydrofluoric acid and nitric acid at 80°C and mixed for 1 hour. Then, the calcined product was washed well with pure water and dried well.

[0171] [Elutriation process]

[0172] Elutriation was performed after the acid treatment process. That is, by the steps of putting the calcined product into an aqueous medium and standing for a certain time, and then removing the supernatant (ultrafine particles do not precipitate but float), the ultrafine particles in the calcined product were removed. The specific conditions are as follows.

[0173] Container used: styrene stick bottle (opening part 81.1 mm, depth 128 mm) with a capacity of 0.5 L

[0174] Height from the bottom surface of the container to the liquid surface: 111 mm

[0175] Aqueous medium: 0.05 mass% aqueous solution of Na hexametaphosphate

[0176] Standing time: as described in Table 1

[0177] Pumping of the supernatant: from the liquid surface height to a height of 66 mm

[0178] Number of times: 5 times

[0179] <Calculation of the average circularity, average of the aspect ratio, and average of the equivalent circle diameter>

[0180] The average circularity, average of the aspect ratio, and average of the equivalent circle diameter of the particles in the obtained phosphor powder were calculated using a flow particle image analyzer FPIA-3000 manufactured by Sysmex Corporation. The specific steps are as follows.

[0181] (1) In a plastic container with a volume of 10 mL, 0.05 g of α-sialon phosphor powder and 10 mL of a 25 mass% aqueous solution of propylene glycol were added, the lid was closed, and it was set in an ultrasonic disperser. Then, a dispersion treatment based on ultrasonic waves at a frequency of 40 kHz was performed for 3 minutes.

[0182] (2) The total amount of the dispersion liquid subjected to the dispersion treatment of the above (1) was added to the device from the sample injection port of the FPIA-3000. Then, measurement was performed in the LPF mode / quantitative counting (total count 36000, number of repeated measurements 1).

[0183] (3) By analyzing the obtained data with the analysis software assembled in the FPIA-3000, the following values were calculated.

[0184] Average circularity of particles having an equivalent circle diameter of 3 to 80 μm

[0185] Average aspect ratio of particles having an equivalent circle diameter of 3 to 80 μm

[0186] Average equivalent circle diameter (μm) of particles having an equivalent circle diameter of 3 to 80 μm

[0187] Average circularity of particles having an equivalent circle diameter of 20 to 60 μm

[0188] Average aspect ratio of particles having an equivalent circle diameter of 20 to 60 μm

[0189] Average equivalent circle diameter (μm) of particles having an equivalent circle diameter of 20 to 60 μm

[0190] <Particle size distribution measurement>

[0191] Measurement was performed by the laser diffraction scattering method based on JIS R1629: 1997 using Microtrac MT3300EXII (manufactured by Microtrac BEL Corp.). 0.5 g of the phosphor powder was added to 100 cc of ion exchange water, and dispersion treatment was performed therein for 3 minutes using an Ultrasonic Homogenizer US-150E (NIHON SEIKI CO., LTD., chip size φ20 mm, Amplitude 100%, oscillation frequency 19.5 kHz, amplitude about 31 μm). Then, particle size distribution measurement was performed using the laser diffraction / scattering type particle size distribution measuring device MT3300EXII. From the obtained particle size distribution, D 50 etc.

[0192] <Manufacture and evaluation of encapsulation (white LED)>

[0193] The phosphor powder obtained in the example or comparative example was added to a thermosetting silicone resin material to perform deaeration and kneading, and a kneaded product was obtained. At this time, the value of (mass of phosphor powder / mass of curable silicone resin material) was made to be 0.6.

[0194] The mixture was encapsulated into a surface-mounted package to which a blue LED element with a peak wavelength of 450 nm was joined, and then heat-cured, thereby producing a white LED.

[0195] The total luminous flux when the produced white LED was energized to emit light was measured by a total luminous flux measuring device (a device in which a 500 mm diameter integrating hemisphere and a spectrophotometer / MCPD-9800 were combined) manufactured by OTSUKA ELECTRONICS CO., LTD. The measurement was performed on 10 white LEDs. Then, the average of the values obtained from each LED was taken as the measured value.

[0196] The luminous property of the package was evaluated based on the value of the total luminous flux divided by the value of the chromaticity y. The larger the value, the more it can be said that the package is high performance.

[0197] Incidentally, dividing the value of the total luminous flux by the chromaticity y is based on the following reason. That is, because in the case where the value of the total luminous flux is directly compared between the examples / comparative examples, the chromaticity does not match, and even if the values (the mass of the phosphor / the mass of the curable silicone resin material) are the same, the chromaticity deviates and the total luminous flux changes, making it difficult to make a simple comparison.

[0198] Information on the production method is summarized in Table 1. Also, the measurement results based on the flow particle image analysis device, the measurement results based on the laser diffraction / scattering method, and the evaluation results of the package (white LED) are summarized in Table 2.

[0199] [Table 1]

[0200]

[0201] [Table 2]

[0202]

[0203] As shown in Table 2, the value of (total luminous flux / chromaticity y) when the package produced using the α-type sapphire phosphor powder (Examples 1 to 3) in which the average circularity of the particles with an equivalent circle diameter of 3 to 80 μm was in the range of 0.85 to 0.95 and the average of the aspect ratios of the particles with an equivalent circle diameter of 3 to 80 μm was 0.65 to 0.85 was larger than the value of (total luminous flux / chromaticity y) when the package produced using the α-type sapphire phosphor powder of Comparative Examples 1 to 4 was evaluated. This indicates that the α-type sapphire phosphor in which the average circularity of the particles with an equivalent circle diameter of 3 to 80 μm and the average of the aspect ratios of the particles with an equivalent circle diameter of 3 to 80 μm are appropriately adjusted like Examples 1 to 3 is preferable for the production of a high-performance LED package.

[0204] This application claims priority based on Japanese Application No. 2023-051828 filed on March 28, 2023, and the entire contents of the application are incorporated herein by reference.

[0205] Symbol Explanation

[0206] 1 phosphor particle

[0207] 30 sealing material

[0208] 40 composite (wavelength conversion member)

[0209] 100 light emitting device

[0210] 120 light emitting element

[0211] 130 heat sink

[0212] 140 case

[0213] 150 first lead frame

[0214] 160 second lead frame

[0215] 170 bonding wire

[0216] 172 bonding wire

Claims

1. An α-type silon phosphor powder, wherein, The average roundness of the α-type silron phosphor particles in this α-type silron phosphor powder, with an equivalent circular diameter of 3–80 μm, is 0.85–0.

95. The average aspect ratio of the α-type silon phosphor particles with an equivalent circular diameter of 3–80 μm in this α-type silon phosphor powder is 0.65–0.

85.

2. The α-type silon phosphor powder according to claim 1, wherein, The α-type silon phosphor powder contains α-type silon phosphor particles with an equivalent circular diameter of 3–80 μm, and the average equivalent circular diameter is 15–35 μm.

3. The α-type silon phosphor powder according to claim 1 or 2, wherein, The average roundness of the α-type silon phosphor particles in this α-type silon phosphor powder, with an equivalent circular diameter of 20–60 μm, is 0.80–0.

90.

4. The α-type silon phosphor powder according to claim 1 or 2, wherein, The average aspect ratio of the α-type silon phosphor particles with an equivalent circular diameter of 20–60 μm in this α-type silon phosphor powder is 0.70–0.

80.

5. The α-type silon phosphor powder according to claim 1 or 2, wherein, The α-type silon phosphor powder contains α-type silon phosphor particles with an equivalent circular diameter of 20–60 μm, and the average equivalent circular diameter is 25–35 μm.

6. The α-type silon phosphor powder according to claim 1 or 2, wherein, The cumulative 50% particle size D of the volume reference was determined by laser diffraction / scattering method. 50 It is 20–40 μm.

7. The α-type silon phosphor powder according to claim 1 or 2, wherein, Let the cumulative 10% particle size of the volume reference determined by laser diffraction / scattering be D. 10 Set the cumulative 50% particle size based on volume as D. 50 Set the cumulative 90% particle size based on volume to D. 90 At that time, (D) 90 -D 10 ) / D 50 The value is 1.05 to 1.

5.

8. A wavelength conversion component comprising an α-type silon phosphor powder as described in claim 1 or 2 dispersed in a sealing material.

9. A light-emitting device comprising a wavelength conversion component as described in claim 8 and a light-emitting element capable of irradiating the wavelength conversion component with excitation light.

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