TW202028415A - Surface-coated phosphor particle, composite and light-emitting device - Google Patents

Abstract

A surface-coated phosphor particle according to an aspect of the invention comprises a phosphor particle formed from an oxynitride phosphor or a nitride phosphor, and a coating layer which is provided on the surface of the phosphor particle and is formed from a metal hydroxide or metal oxide containing one or more elements selected from the group consisting of aluminum, titanium, zirconium, yttrium, and hafnium. The surface-coated phosphor particle has a hot water extraction electrical conductivity index ΔΩ defined below of not more than 2.0 mS/m. (Method of calculating hot water extraction electrical conductivity index) (1) Measure the electrical conductivity Ω₀ of ion exchange water at 25°C. (2) Disperse 1 g of the surface coated phosphor particle in 30 ml of the ion exchange water, place the resulting dispersion in a pressure resistant vessel and heat for 16 hours at 150°C, and then add 20 ml of ion exchange water and measure the electrical conductivity Ω₁ after cooling to 25°C. (3) The difference ΔΩ between the electrical conductivity Ω₁ and the electrical conductivity Ω₀ (= electrical conductivity Ω₁ - electrical conductivity Ω₀ ) is deemed the hot water extraction electrical conductivity index ΔΩ.

Description

Surface coated phosphor particles, composite body and light emitting device

The present invention relates to surface-coated phosphor particles, composites and light-emitting devices.

In recent years, there has been progress in the development of light-emitting devices that combine semiconductor light-emitting elements such as LEDs and phosphors that absorb part of the light from the semiconductor light-emitting elements and then convert the absorbed light into long-wavelength wavelength-converted light to emit light. . As far as phosphors are concerned, nitride phosphors and oxynitride phosphors with relatively stable crystal structures have attracted attention.

Patent Document 1 discloses that in order to increase the brightness of a β-type silicon aluminum oxynitride (SiAlON) phosphor, the surface of a β silicon aluminum oxynitride phosphor is coated with a metal hydroxide. Patent Document 2 cites a conventional technique of coating the surface of phosphor particles with a glass material in order to suppress the hydrolysis of phosphors containing sulfides and moisture in the air. In addition, it is pointed out that the coating will affect the dispersibility of the phosphor particles to the sealing material. In order to improve the dispersibility of the phosphor to the sealing material, it is disclosed that the surface of the phosphor particles is coated with metal oxide particles. The method of covering. Patent Document 3 discloses that in order to improve the gas barrier properties of the coating layer provided on the surface of the phosphor particles, the glass powder adhering to the surface of the phosphor particles is melted by heating so as to be on the surface of the phosphor particles. Form a continuous film. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2014-197635 A [Patent Document 2] JP 2008-291251 A [Patent Document 3] JP 2009-13186 A

[The problem to be solved by the invention]

After investigating the characteristics of a light-emitting device in which a composite body obtained by sealing a phosphor with a sealing material and an LED are combined, the inventors have found that the luminous intensity decreases slightly over time. The reason for this phenomenon was investigated, and it was determined that the moisture moving through the sealing material contacted the phosphor, and the metal component in the phosphor was ionized and eluted into the moisture. The crystalline structure of the phosphor gradually changed. As a result, the wavelength conversion efficiency of the phosphor is reduced, which in turn leads to a reduction in the luminous intensity of the light-emitting device. [Means to solve the problem]

According to the present invention, there is provided a surface-coated phosphor particle, comprising phosphor particles composed of oxynitride phosphor or nitride phosphor; and arranged on the surface of the phosphor particle, comprising: A coating layer composed of metal hydroxides or metal oxides of one or more elements in the group composed of aluminum, titanium, zirconium, yttrium and hafnium, the surface of which is covered with hot water as defined below by phosphor particles The extraction conductivity index ΔΩ is 2.0 mS/m or less. (Calculation method of conductivity index for hot water extraction) (1) Measure the conductivity Ω ₀ of ion exchange water at 25°C. (2) Disperse 1g of the surface-coated phosphor particles in 30ml of ion exchange water, put it in a pressure vessel and heat it at 150°C for 16 hours, add 20ml of ion exchange water and cool it to 25°C. Measure the conductivity Ω ₁ . (3) The difference ΔΩ between the conductivity Ω ₁ and the conductivity Ω ₀ (= conductivity Ω ₁ -conductivity Ω ₀ ) is defined as the hot water extraction conductivity index ΔΩ.

Furthermore, according to the present invention, there is provided a composite including the above-mentioned surface-coated phosphor particles and a sealing material for sealing the surface-coated phosphor particles.

Furthermore, according to the present invention, there is provided a light-emitting device including a light-emitting element that emits excitation light, and the above-mentioned composite that converts the wavelength of the excitation light. [Effects of Invention]

According to the present invention, it is possible to suppress the elution of the metal components constituting the phosphor particles into moisture.

The inventors intensively studied the technology for suppressing the elution of the metal components constituting the phosphor particles in the form of ions in water, and found that it is important to control the form of the coating layer formed on the surface of the phosphor particles to a high degree. The selection of the material constituting the coating layer is particularly important, and the present invention has been completed. Hereinafter, embodiments of the present invention will be described in detail.

(Surface coated phosphor particles) The surface-coated phosphor particles of the embodiment include phosphor particles and a coating layer provided on the surface of the phosphor particles. Hereinafter, each structure of the surface-coated phosphor particles of this embodiment will be described.

(Fluorescent particles)

The phosphor particles are composed of oxynitride phosphors or nitride phosphors. As for oxynitride phosphors, for example, α-type silicon aluminum oxynitride phosphors containing Eu, β-type silicon aluminum oxynitride phosphors containing Eu, etc. can be cited.

The α-type silicon aluminum oxynitride phosphor system containing Eu is represented by the general formula: M _x Eu _y Si _{12-(m + n)} Al _{(m + n)} O _n N _16-n . In this general formula, M is an element selected from the group consisting of Li, Mg, Ca, Y, and lanthanides (except La and Ce), which contains at least one element of Ca. Let the valence of M be For a, ax+2y=m, 0>x≦1.5, 0.3≦m>4.5, 0>n>2.25.

The β-type silicon aluminum oxynitride phosphor containing Eu is solidified in β-type silicon aluminum oxynitride represented by the general formula: Si _6-z Al _z O _z N _8-z (z=0.005~1) A phosphor containing divalent europium (Eu ^{2 +} ) as the luminescent center is dissolved.

As for nitride phosphors, for example, CASN phosphors containing Eu, SCASN phosphors containing Eu, etc. can be cited.

CASN phosphors containing Eu refer to, for example, red phosphors represented by the general formula CaAlSiN ₃ : Eu ^{2 +} , with Eu ^{2 +} as the activator, and a crystal composed of alkaline earth silicon nitride as the matrix. In addition, the definition of CASN phosphors containing Eu in this specification excludes SCASN phosphors containing Eu.

SCASN phosphors containing Eu, for example, are represented by the general formula (Sr,Ca)AlSiN ₃ : Eu ^{2 ＋} , Eu ^{2 ＋ is} used as the activator, and the crystal made of alkaline earth silicon nitride is used as the matrix of the red fluorescent body.

The phosphor particles of this embodiment are preferably made of the above-mentioned Eu-containing α-type silicon aluminum oxynitride phosphor, Eu-containing β-type silicon aluminum oxynitride phosphor, Eu-containing CASN phosphor or Eu The composition of SCASN phosphor is ideal.

In addition, the particle diameter of the phosphor particles is not particularly limited, and can be appropriately adjusted so as to obtain the dispersibility in the following sealing material and the desired wavelength conversion efficiency.

(Coating layer) In this embodiment, the surface of the phosphor particles is provided with a metal hydroxide or metal oxide containing more than one element selected from the group consisting of aluminum, titanium, zirconium, yttrium and hafnium The covering layer formed by objects. The metal hydroxide or metal oxide has excellent transparency and stability. Among them, aluminum hydroxide or aluminum oxide is better than aluminum hydroxide or aluminum oxide from the viewpoints of moisture barrier properties, cost suppression properties, and coating properties to phosphor particles. ideal. The coating layer may be an aggregate formed by agglomeration of a plurality of particles composed of metal hydroxide or metal oxide; preferably composed of metal hydroxide or metal oxide, and the phosphor particles are continuously coated The continuous coating layer. Here, the continuous coating layer is a layered structure formed by a continuous film of a metal hydroxide or a metal oxide, and is different from an aggregate formed by dense aggregation of a plurality of particles as in the invention described in Patent Document 2. structure. The continuous coating layer may also have a concavo-convex structure formed with a plurality of non-penetrating recesses.

The surface coverage rate of the phosphor particles made of the coating layer is preferably 50% or more, and more preferably 70% or more. By making the surface coverage rate by the coating layer as described above, it is possible to further suppress the amount of elution of the metal component of the phosphor particles in the form of ions. In addition, the coating layer preferably coats the entire surface of the phosphor particles.

The surface coverage by the coating layer can be evaluated by X-ray photoelectron spectroscopy (XPS) measurement. Specifically, it focuses on the element Si contained in the phosphor particles and not contained in the metal hydroxide or metal oxide constituting the coating layer. The XPS measurement is used to obtain the Si on the surface of the phosphor particles. Content rate (atm%: atomic percentage). Without the following surface treatment, the Si content rate in the phosphor particles that are not coated with metal hydroxides or metal oxides is set as A1, and the phosphor particles that are the calculation target of the surface coverage rate When the Si content in A2 is set as A2, the surface coverage by the coating layer can be calculated by the following formula. Surface coverage (%)=(A1-A2)/A1×100

The lower limit of the thickness of the coating layer is preferably 0.01 μm or more, more preferably 0.1 μm or more. In addition, the upper limit of the thickness of the coating layer is preferably 10 μm or less, and more preferably 5 μm or less. By making the thickness of the coating layer 0.01 μm or more, it is possible to further suppress the amount of metal components contained in the phosphor particles eluted in the form of ions. In addition, by making the thickness of the coating layer 10 μm or less, it is possible to suppress a decrease in the wavelength conversion efficiency of the phosphor particles coated on the surface.

(Hot water extraction conductivity index) The hot water extraction conductivity index ΔΩ defined below of the surface-coated phosphor particles of the present embodiment is 2.0 mS/m or less. (Calculation method of conductivity index for hot water extraction) (1) Measure the conductivity Ω ₀ of ion exchange water at 25°C. (2) Using a dispersing device such as an ultrasonic disperser, disperse 1g of surface-coated phosphor particles in 30ml of ion exchange water, put it in a pressure vessel and heat at 150°C for 16 hours, then add 20ml of ion exchange water And measure the conductivity Ω _{1 in} the state that has been cooled to 25°C. (3) The difference ΔΩ between the conductivity Ω ₁ and the conductivity Ω ₀ (= conductivity Ω ₁ -conductivity Ω ₀ ) is defined as the hot water extraction conductivity index ΔΩ. The hot water extraction conductivity index becomes an index indicating that the smaller the value, the smaller the amount of metal ions eluted from the phosphor particles into the water.

(Method for manufacturing surface-coated phosphor particles) An example of a method for producing surface-coated phosphor particles with a coating layer composed of a metal oxide includes, for example, a production method including the following steps: (1) By including metal hydrogen on the surface of the phosphor particles Oxide substances (particles, etc.) are used to form a coating layer, and (2) by applying heat treatment, the metal hydroxide is changed into a metal oxide and the coating layer is converted into a continuous coating layer, thereby obtaining a metal The step of coating the surface of the continuous coating layer of oxide with phosphor particles. In this manufacturing method, in order to be converted into a continuous coating layer by heat treatment, it is important to densely coat the coating layer formed of particles containing metal hydroxides. Regarding the manufacturing method of such surface-coated phosphor particles, three examples including manufacturing method examples 1 to 3 will be described below.

[Manufacturing method example 1] Manufacturing method example 1 includes a slurry preparation step, a stirring step, a pH adjustment step, agitation, washing, a filtration step, a drying step, and a heating step. The details of each step are described below.

(Slurry preparation step) The phosphor powder, ion-exchanged water, and metal hydroxide-containing substances are mixed in appropriate amounts to prepare a phosphor-containing slurry. It is preferable that the pH of the slurry obtained here, the surface potential of the phosphor particles, and the surface potential of the metal hydroxide-containing substance are all positive values. The surface potential of the phosphor particles and the metal hydroxide-containing substance can be measured, for example, by a boundary potential measuring device. In addition, when aluminum hydroxide is used as a substance containing a metal hydroxide, it can be used in the form of aluminum hydroxide in a sol state (it is also called alumina sol conventionally) or an aluminum hydroxide aqueous solution.

(Stirring step) The slurry obtained in the slurry preparation step is stirred using a stirring means such as a stirrer or a stirring device to fully disperse the phosphor powder and the metal hydroxide-containing substance.

(pH adjustment step) In the pH adjustment step, an alkali agent is dropped into the obtained slurry at a predetermined dropping speed to adjust the pH to 9 or higher. As for the alkaline agent, alkaline aqueous solutions such as NH ₃ aqueous solution and NaOH aqueous solution can be cited. In the process of increasing the pH value due to the addition of the alkali agent, the surface potential of the substance containing the metal hydroxide becomes positive, and the surface potential of the phosphor particles becomes negative. Thereby, it becomes easy to densely adhere the substance containing the metal hydroxide on the surface of the phosphor particles. Specifically, when β-type silicon aluminum oxynitride phosphor particles are used as phosphor particles, and alumina sol is used as a substance containing metal hydroxide, the surface potential of aluminum hydroxide changes when the pH is above 6.5 Positive, the surface potential of the β-type silicon aluminum oxynitride phosphor particles becomes negative. Thereby, the electrostatic attractive force between the two makes it easy to densely adhere the substance containing aluminum hydroxide on the surface of the β-type silicon aluminum oxynitride phosphor particles.

In addition, in the pH adjustment step, when the alkaline aqueous solution is used as the alkaline agent, by adjusting the concentration, dropping speed, and dropping time of the alkaline aqueous solution, it is possible to control the metal hydroxides that adhere to the surface of the phosphor particles. The thickness and surface coverage of the material.

(Stirring, washing, filtering steps) Use a stirring means such as a stirrer to stir the slurry obtained through the above pH adjustment step to fully disperse the phosphor particles, and then wash it with a cleaning solution such as ion exchange water. After that, the phosphor powder (the phosphor particles coated with the substance containing the metal hydroxide) is taken out by filtration means such as suction filtration.

(Drying step) The obtained phosphor powder is sufficiently dried and heated for a predetermined time to obtain a phosphor powder composed of a plurality of phosphor particles whose surface is densely covered with a substance containing a metal hydroxide.

(Heating step) By subjecting the obtained phosphor powder to heat treatment, the layer containing the metal hydroxide densely covering the surface of the phosphor particles is oxidized and converted into a metal oxide, and a metal oxide is produced It is called the continuous film-like form of the continuous coating layer. The temperature when the phosphor powder is heated is preferably 500°C or more and 1000°C or less. Especially when alumina sol is used as the substance containing metal hydroxides, the heating temperature should be 500°C or more and 600°C or less. ideal. According to the above steps, a surface-coated phosphor particle with a continuous coating layer composed of a metal oxide formed on the surface of the phosphor particle is manufactured.

[Manufacturing method example 2] Production method example 2 includes a slurry preparation step, a stirring step, a stirring, washing, filtering step, a drying step, and a heating step. In the production method example 1, an alkali agent was added after the stirring step to adjust the pH, but in the production method example 2, an alkali agent was added in the slurry preparation step to adjust the pH.

As in manufacturing method example 1, if an alkali agent is added to adjust the pH after the stirring step, the coating layer made of the substance containing the metal hydroxide can be used to form a denser coating layer. The speed of adding the alkali agent can also be adjusted to further improve the density of the coating. By forming such a dense coating layer, a continuous coating layer can be stably obtained by subsequent heat treatment. On the other hand, as in the manufacturing method example 2, if the pH is adjusted in the slurry preparation step, the manufacturing step can be shortened.

[Manufacturing method example 3] Production method example 3 includes a slurry preparation step, a stirring step, a pH adjustment step, agitation, washing, a filtration step, a drying step, and a heating step. The details of each step are described below. In manufacturing method example 1 and manufacturing method example 2, a substance containing metal hydroxide is used as the starting material of the continuous coating layer, but in manufacturing method example 3, a precursor material of the metal hydroxide is used as the starting material of the continuous coating layer. Starting materials.

(Slurry preparation step) In this example, the phosphor powder, ion-exchanged water, and the precursor material of the metal hydroxide were mixed in appropriate amounts to prepare a phosphor-containing slurry. When the metal hydroxide is aluminum hydroxide, sodium aluminate is used as its precursor. The obtained slurry is usually strongly alkaline, and specifically, preferably has a pH of 12 or higher, and more preferably has a pH of 13 or higher. The metal hydroxide is precipitated by adding acids such as hydrochloric acid and sulfuric acid to this slurry. Thereby, a phosphor-containing slurry containing phosphor powder, ion-exchanged water, and metal hydroxide is obtained. The pH of the phosphor-containing slurry obtained here is such that the surface potential of the phosphor particles and the surface potential of the metal hydroxide are both in the range of negative values. Specifically, it is preferably pH 11 or more, more preferably Above pH12.

(Stirring step) Use a stirring means such as a stirrer or a stirring device to stir the slurry obtained in the slurry preparation step to fully disperse the phosphor powder and the metal hydroxide.

(pH adjustment step) In the pH adjustment step, acids such as hydrochloric acid and sulfuric acid are dropped into the obtained slurry at a predetermined dropping speed to adjust the pH to 9 or less. In the process of lowering the pH value by the addition of acid, by making one of the surface potential of the metal hydroxide and the surface potential of the phosphor particles positive and the other negative, the It becomes easy for the metal hydroxide to adhere densely to the surface of the optical body particle. Specifically, β-type silicon aluminum oxynitride phosphor particles are used as phosphor particles. When aluminum hydroxide is precipitated from a slurry containing sodium aluminate, the surface potential of aluminum hydroxide becomes positive when the pH is below 10 , The surface potential of β-type silicon aluminum oxynitride phosphor particles becomes negative. With this, the electrostatic attraction between the two makes it easy to adhere the aluminum hydroxide-based densely on the surface of the β-type silicon aluminum oxynitride phosphor particles. In addition, in the pH adjustment step, by adjusting the concentration of the acid dropped into the slurry, the dropping speed, and the dropping time, the thickness and the surface coverage of the metal hydroxide attached to the surface of the phosphor particles can be controlled.

After pH adjustment, similar to the production method example 1, by performing a stirring step, a pH adjustment step, agitation, washing, a filtration step, a drying step, and a heating step, it is produced that a metal is formed on the surface of the phosphor particles. The surface of the continuous coating layer composed of oxide is coated with phosphor particles. Furthermore, in the production method example 3, after the addition of the acid in the slurry preparation step (the step of precipitating the metal hydroxide from the precursor), the stirring step is performed, and then the acid is added to adjust the pH. For other methods, the slurry preparation step and the stirring step can also be paralleled. From the slurry preparation step, acid is continuously added to adjust the pH so that the surface potential of the metal hydroxide and the surface potential of the phosphor particles , The surface potential of one side is positive, and the surface potential of the other side is negative.

Here, by appropriately selecting, for example, the type and amount of the metal oxide, the method of attaching the metal oxide to the surface of the phosphor particles, etc., the above-mentioned hot water extraction conductivity index can be controlled. Among them, the elements for making the hot water extraction conductivity index within the desired numerical range include, for example, pH adjustment conditions for densely attaching a substance containing metal hydroxide to the surface of phosphor particles, and for dense The heating conditions for the conversion of the metal hydroxide-containing substance solidly attached to the surface of the phosphor particles into the metal oxide.

According to the surface-coated phosphor particles of this embodiment, in order to make the hot water extraction conductivity index ΔΩ below 2.0mS/m, a coating layer made of metal oxide is formed on the surface of the phosphor particles to enable the surface coating When moisture exists around the phosphor particles, the moisture is prevented from entering the phosphor particles. As a result, the amount of ions eluted by moisture is reduced, and the deterioration of phosphor particles is suppressed.

(Light-emitting device) Fig. 1 is a schematic cross-sectional view showing the structure of the light emitting device according to the embodiment. As shown in FIG. 1, the light emitting device 10 includes a light emitting element 20, a heat sink 30, a housing 40, a first lead frame 50, a second lead frame 60, a bonding wire 70, a bonding wire 72, and a composite body 80.

The light emitting element 20 is installed in a predetermined area on the upper surface of the heat sink 30. By mounting the light emitting element 20 above the heat sink 30, the heat dissipation of the light emitting element 20 can be improved. In addition, a packaging substrate may be used instead of the heat sink 30.

The light-emitting element 20 is a semiconductor element that emits excitation light. For the light emitting element 20, for example, an LED chip that emits light having a wavelength of 300 nm or more and 500 nm or less from near ultraviolet light to blue light can be used. One of the electrodes (not shown) mounted on the upper side of the light emitting element 20 is connected to the surface of the first lead frame 50 through a bonding wire 70 such as a gold wire. In addition, the other electrode (not shown) formed above the light-emitting element 20 is connected to the surface of the second lead frame 60 through a bonding wire 72 such as a gold wire.

The housing 40 is formed with a funnel-shaped recess whose aperture gradually expands from the bottom surface upward. The light emitting element 20 is provided on the bottom surface of the recess. The wall surface surrounding the recess of the light-emitting element 20 functions as a reflector.

The composite body 80 is filled in the recess formed by the wall surface of the housing 40. The composite 80 is a wavelength conversion member that lengthens the wavelength of the excitation light emitted from the light-emitting element 20. When the composite of this embodiment is used as the composite 80, the surface-coated phosphor particles 82 of this embodiment are dispersed in a sealing material 84 such as resin. The light-emitting device 10 emits a mixed color of the light of the light-emitting element 20 and the light emitted from the surface-coated phosphor particles 82 that are excited by absorbing the light of the light-emitting element 20. The light-emitting device 10 preferably uses the color mixture of the light of the light-emitting element 20 and the light emitted from the surface-coated phosphor particles 82 to emit white light.

As described above, the light-emitting device 10 of this embodiment uses hot water to extract the surface-coated phosphor particles 82 with a conductivity index ΔΩ of 2.0 mS/m or less, which not only suppresses the release of fluorescent particles in the sealing material 84 due to moisture. The elution of the ions of the photobody particles can also suppress the decrease in the luminous intensity of the light-emitting device 10, so that the reliability of the light-emitting device 10 can be improved.

Above, the embodiments of the present invention have been described, but these are only examples of the present invention, and various configurations other than the above can be adopted. For example, in FIG. 1, a surface-mounted LED is taken as an example of the light-emitting device of the relevant embodiment, but the light-emitting device of the relevant embodiment may also be a cannonball-type LED.

Above, the embodiments of the present invention have been described, but these are only examples of the present invention, and various configurations other than the above can be adopted. [Example]

Hereinafter, the present invention will be described with examples and comparative examples, but the present invention should not be limited to these.

(Manufacturing Example 1: β-type silicon aluminum oxynitride) A V-type mixer (S-3 manufactured by Tsutsui Rikagaku Co., Ltd.) was used to mix α-type silicon nitride powder (SN-E10 grade, oxygen) manufactured by Ube Kosan Co., Ltd. Content 1.0% by mass) 95.43% by mass, Tokuyama's aluminum nitride powder (F grade, oxygen content of 0.8% by mass) 3.04% by mass, Daming Chemical Co.'s alumina powder (TM-DAR grade) 0.74% by mass, Shin-Etsu 0.79% by mass of europium oxide powder (RU grade) manufactured by Chemical Industry Co., Ltd. was further passed through a 250 μm mesh sieve and aggregates were removed to obtain a raw material mixed powder. The blending ratio (mass%) here is designed so that the Europium oxide in the β-type silicon aluminum oxynitride is removed from the general formula of Si _6-z Al _z O _z N _8-z , and the Si/Al ratio The calculated z=0.25.

200g of the raw material mixed powder containing the composition of the above blending ratio is filled into a cylindrical boron nitride container (manufactured by Denki Kagaku Co., Ltd., N-1 grade) with an inner diameter of 10 cm and a height of 10 cm, and an electric furnace with a carbon heater In a 0.8MPa pressurized nitrogen environment, heat treatment at 2000°C for 12 hours. Because the sample after the heat treatment will slowly agglomerate into a block, the agglomerate is coarsely crushed with a hammer, and then a supersonic jet mill (manufactured by Japan Pneumatic Industry Co., Ltd., PJM-80SP) ) Smash. The pulverization conditions were such that the sample feed rate was 50 g/min and the pulverization air pressure was 0.3 MPa. The pulverized powder was passed through a sieve of 45 μm mesh. Moreover, the pass rate of the sieve is 95%.

Fill a cylindrical boron nitride container with a lid with an inner diameter of 5 cm and a height of 3.5 cm with 20 g of the crushed powder that has passed through the sieve, and perform annealing at 1500°C for 8 hours in an electric furnace with a carbon heater in an argon atmosphere at atmospheric pressure deal with. The powder after annealing treatment is soaked in a 1:1 mixed acid of 50% hydrofluoric acid and 70% nitric acid at 75°C for 30 minutes. Repeat the decantation of the acid-treated powder precipitation and the removal of the supernatant and the powder as it is until the pH is above 5 and the supernatant becomes transparent. The final precipitate is filtered and dried to obtain the production example 1 Phosphor particles (β-type silicon aluminum oxynitride phosphor powder). As a result of powder X-ray diffraction measurement, the existing crystal orientation is β-type silicon aluminum oxynitride single phase. According to ICP emission spectrophotometric analysis, the measured Si, Al and Eu contents are 57.7, 2.29, and 0.62% by mass respectively. The z value calculated from the Si and Al contents is 0.24. The blending ratio of Production Example 1 is described in Table 1.

[Table 1]

(Example 1) The phosphor particles of Production Example 1 (β-type silicon aluminum oxynitride phosphor powder) were subjected to surface treatment using the following procedure.

[Surface treatment] (1) 10 g of the phosphor particles of Production Example 1, 150 ml of ion exchange water, and 7.11 g of alumina sol (alumina sol 520-A, manufactured by Nissan Chemical Co., Ltd.) were mixed to prepare a slurry. The pH of the obtained slurry was 4.1. The surface potential of aluminum hydroxide and the surface potential of phosphor particles were measured using a boundary potential measuring device at pH 4.1. As a result, the surface potential of aluminum hydroxide was 44 mV, and the surface potential of phosphor particles was 16 mV. (2) Use a stirrer to stir the slurry for 15 minutes. (3) Ammonia water of 0.05% by weight is slowly dropped into the slurry, and the pH is adjusted to 9 after 3 minutes of dropping time. When the pH was 9, the surface potential of aluminum hydroxide and the surface potential of the phosphor particles were measured using a boundary potential measuring device. As a result, the surface potential of the aluminum hydroxide was 13 mV, and the surface potential of the phosphor particles was -25 mV. (4) The slurry was stirred for 60 minutes with a stirrer, and then washed with ion-exchange water, and then suction filtered to obtain phosphor powder. (5) Dry the obtained phosphor powder at 105°C for 15 hours. (6) The phosphor powder after the drying treatment was heated in an electric furnace at 600°C for 1 hour to obtain the surface-coated phosphor particles of Example 1. The surface-coated phosphor particles of Example 1 were observed with a scanning electron microscope (SEM). 2 is an SEM image of the surface-coated phosphor particles of Example 1. FIG. As shown in Figure 2, it was confirmed that the aluminum oxide is not dotted on the surface of the phosphor particles, but is continuously coated to form a continuous coating layer.

(Example 2) For the phosphor particles of Production Example 1, 4.74 g of AERODISP W 630 (manufactured by Evonik Resource Efficiency GmbH) was added instead of the alumina sol in the above surface treatment (1), and the pH of the obtained slurry was 5.0 Except for this, the same surface treatment as in Example 1 was performed to make the surface-coated phosphor particles of Example 2. The surface potential of aluminum hydroxide and the surface potential of phosphor particles were measured using a boundary potential measuring device at pH 5.0. As a result, the surface potential of aluminum hydroxide was 42 mV, and the surface potential of phosphor particles was 11 mV. The surface-coated phosphor particles of Example 2 were observed using SEM. 3 is an SEM image of the surface-coated phosphor particles of Example 1. FIG. As shown in Figure 3, it was confirmed that the alumina was not dotted on the surface of the phosphor particles, but was continuously coated to form a continuous coating layer.

(Comparative example 1) Regarding the phosphor particles of Production Example 1, the above-mentioned surface treatment was not performed, and it was used as Comparative Example 1. The phosphor particles of Comparative Example 1 were observed using SEM. FIG. 4 is an SEM image of phosphor particles of Comparative Example 1. FIG. As shown in Fig. 4, the phosphor particles of Comparative Example 1 are exposed on the entire surface.

[Calculation method of hot water extraction conductivity index] The hot water extraction conductivity index of the surface-coated phosphor particles of each example and the phosphor particles of Comparative Example 1 was calculated by the following methods. The results of the hot water extraction conductivity index are shown in Table 2. (1) Measure the conductivity Ω ₀ of ion exchange water at 25°C. (2) Disperse 1g of surface-coated phosphor particles (or phosphor particles) in 30ml of ion-exchanged water with an ultrasonic disperser, put it in a pressure vessel and heat it at 150°C for 16 hours, then add ions Exchange 20ml of water and measure the conductivity Ω _{1 in a} state where it has been cooled to 25°C. (3) The difference ΔΩ between the conductivity Ω ₁ and the conductivity Ω ₀ (= conductivity Ω ₁ -conductivity Ω ₀ ) is defined as the hot water extraction conductivity index ΔΩ.

[Reliability Test] The reliability test of the LED package equipped with the surface-coated phosphor particles of each example and the phosphor particles of Comparative Example 1 was evaluated by the following methods. The results obtained from the reliability test are shown in Table 2. The LED packaging system uses the structure of the light-emitting device shown in FIG. 1 as the standard. The phosphor is mounted on the LED package by wire-bonding the electrode on the LED on the concave bottom of the housing with the lead frame, and then mix it with the liquid silicone resin (OE6656, East). Phosphor particles in Lidow Corning Co., Ltd. are injected into the recess of the housing from the micro syringe. After the phosphor particles are mounted, they are cured at 120°C, and then cured and sealed at 110°C for 10 hours. The LED uses a peak wavelength of 448nm and a chip size of 1.0mm×0.5mm.

For the LED package equipped with the surface-coated phosphor particles of each example and the phosphor particles of Comparative Example 1 obtained by the above method, the light beam was measured, and the initial value was L0. In addition, after leaving it at 85°C and 85%RH for 500 hours, it was taken out and dried at room temperature, and its beam L1 was measured, and then the reliability coefficient M (=L1/L0×100) was calculated. The qualified condition of the reliability test is that the reliability coefficient M is above 95%. This is a value that cannot be achieved with phosphor particles that are not highly reliable. It has been confirmed that the LED packaging system equipped with the surface-coated phosphor particles of Example 1 and Example 2 satisfies this qualification condition. It is assumed that the result is due to the fact that in the surface-coated phosphor particles of Example 1 and Example 2, the coating layer formed on the surface of the phosphor particles suppresses the elution of the metal components constituting the phosphor particles Into the moisture. [Table 2]

This application claims priority based on Japanese Application No. 2018-200304 filed on October 24, 2018, and the entire content is incorporated into the present invention.

10: Light-emitting device 20: Light-emitting element 30: heat sink 40: shell 50: 1st lead frame 60: 2nd lead frame 70: Joining line 72: joint line 80: Complex 82: Surface coated phosphor particles 84: sealing material

The above objectives, and other objectives, features, and advantages can be further understood by the preferred embodiments described below and the accompanying drawings.

[Fig. 1] A schematic cross-sectional view showing the structure of the light-emitting device of the embodiment. [Fig. 2] An SEM image of the surface-coated phosphor particles of Example 1. [Fig. [Figure 3] SEM image of the surface-coated phosphor particles of Example 2. [Figure 4] SEM image of the phosphor particles of Comparative Example 1.

10: Light-emitting device

20: Light-emitting element

30: heat sink

40: shell

50: 1st lead frame

60: 2nd lead frame

70: Joining line

72: joint line

80: Complex

82: Surface coated phosphor particles

84: sealing material

Claims (6)

A surface-coated phosphor particle, comprising: a phosphor particle composed of an oxynitride phosphor or a nitride phosphor, and a coating layer, which is provided on the surface of the phosphor particle, and is selected from Composed of metal hydroxides or metal oxides of one or more elements from the group consisting of aluminum, titanium, zirconium, yttrium, and hafnium; and the surface of the phosphor particles coated with the hot water extraction conductivity as defined below The index ΔΩ is below 2.0mS/m; The method of calculating the conductivity index of hot water extraction: (1) Measure the conductivity of ion-exchanged water at 25℃ Ω ₀ ; (2) Disperse 1g of the surface-coated phosphor particles in Put 30ml of the ion-exchanged water into a pressure vessel and heat it at 150°C for 16 hours, then add 20ml of ion-exchange water and measure the conductivity Ω ₁ after cooling to 25°C; (3) Change the conductivity Ω ₁ The difference ΔΩ with the conductivity Ω ₀ (= conductivity Ω ₁ -conductivity Ω ₀ ) is defined as the hot water extraction conductivity index ΔΩ. For example, the surface-coated phosphor particles in the first item of the scope of patent application, wherein the coating layer is a continuous coating layer that continuously coats the surface of the phosphor particles. For example, the surface-coated phosphor particles of item 1 in the scope of patent application, wherein the coating layer is composed of aluminum hydroxide or aluminum oxide. For example, the surface-coated phosphor particles of item 1 in the scope of patent application, wherein the phosphor particles are made of α-type silicon aluminum oxynitride phosphor containing Eu, and β-type silicon aluminum oxynitride phosphor containing Eu Body, CASN phosphor containing Eu or SCASN phosphor containing Eu. A composite body is provided with a surface-coated phosphor particle as in the first item of the scope of patent application, and a sealing material for sealing the surface-coated phosphor particle. A light emitting device, including: A light-emitting element that emits excitation light, and A composite body that changes the wavelength of the excitation light as in item 5 of the scope of patent application.

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