KR102187046B1 - Glass composition for photo-conversing medium and ceramic phosphor plate including the same - Google Patents

Abstract

An embodiment of the present invention is an oxide mixture consisting of silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ) and zinc oxide (ZnO); And an oxide containing a metal of Group I or II, wherein the content of the oxide containing the boron oxide and the metal of the Group I or II is 35% by weight or less of the total composition A glass composition for use, and a glass frit obtained by vitrifying the glass composition for a photoconversion device as a matrix, and to a ceramic phosphor plate obtained by sintering at least one type of phosphor.

Description

Photoconversion device glass composition and ceramic phosphor plate including the same {GLASS COMPOSITION FOR PHOTO-CONVERSING MEDIUM AND CERAMIC PHOSPHOR PLATE INCLUDING THE SAME}

An embodiment of the present invention relates to a glass frit obtained by vitrifying a glass composition constituting a ceramic phosphor plate used in a photoconversion device, and a ceramic phosphor plate including the same.

White LEDs are attracting attention as a high-efficiency, high-reliability white illumination light source, and some of them are already being used for use as small-scale light sources of small power. There are various methods of implementing a white LED, but the most commonly used method is molding a blue LED element with a yellow phosphor and a resin as a matrix. However, because blue light has strong energy, it is easy to deteriorate the resin. Therefore, when the white LED of this structure is used for a long period of time, the color of light emitted changes because the resin is discolored. In addition, since it is molded with resin, heat dissipation from the device is difficult, so that the temperature is liable to rise. Due to this temperature, there is a problem that the luminous color shifts toward yellow.

In order to solve this problem, a phosphor plate using a ceramic sintered body as a matrix material of the phosphor was applied. Phosphors used in such a phosphor plate are limited to oxide phosphors, in particular, Yttrium Aluminum Garnet (YAG) series phosphors. When only oxide phosphors are used, it is difficult to implement various color coordinates and color temperatures. In addition, when only oxide phosphors such as YAG are applied, the heat resistance temperature is required to be 800°C or higher, so the composition of the glass does not need to be complicated. However, in order to realize various color temperatures, an appropriate amount of the red phosphor and the yellow phosphor must be mixed and used. For this purpose, since these phosphors are weak to heat, an alkali metal or alkaline earth metal is added to the glass composition to lower the sintering temperature. The composition needs to be adjusted.

However, due to the nature of the material, when used for a long period of time, the transmittance of the glass may decrease due to the reaction between the moisture and the composition of the glass, and a whitening phenomenon may occur (see FIGS. 1 and 2, FIG. 1(a)). %) Before the reliability evaluation input, FIG. 1(b) shows the high temperature, high humidity reliability evaluation input). Efflorescence is known that B, Na, and Li-based elements can affect the efflorescence, but in particular, Na elements easily form hydrates. 3 shows a mechanism in which whitening occurs due to the formation of hydrates due to moisture and free elements, particularly sodium. In this way, due to corrosion and hydrate formation, a step of about 5 to 8 µm is generated on the surface (photo on the right of FIG. 2).

On the other hand, another factor that accelerates the whitening phenomenon is pores inside the phosphor plate. 3 is a scanning electron microscope (SEM) photograph of pores generated on the surface. When a large amount of pores is generated, a reaction area increases due to an increase in surface area, which may be a factor that accelerates whitening.

An embodiment of the present invention is designed to solve the problems of the prior art as described above, and an oxide mixture consisting of silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ) and zinc oxide (ZnO); And an oxide containing a metal of Group I or II, wherein the content of the oxide containing the boron oxide and the metal of the Group I or II is 35% by weight or less of the total composition It is an object of the invention to provide a ceramic phosphor plate obtained by sintering at least one type of phosphor using a glass composition for use and a glass frit obtained by vitrifying the glass composition for a photoconversion device as a matrix.

In order to achieve the above technical problem, silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ) and an oxide mixture consisting of zinc oxide (ZnO); And an oxide containing a metal of Group I or II, wherein the content of the oxide containing the boron oxide and the metal of the Group I or II is 35% by weight or less of the total composition It provides a glass composition for use.

In another aspect of the present embodiment, there is provided a ceramic phosphor plate obtained by using a glass frit obtained by vitrifying the glass composition for a photoconversion device as a matrix, and sintering at least one type of phosphor.

According to an embodiment, an oxide mixture consisting of silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ) and zinc oxide (ZnO); And an oxide containing a metal of Group I or II, wherein the content of the oxide containing the boron oxide and the metal of the Group I or II is 35% by weight or less of the total composition The main factor causing the whitening phenomenon by implementing a ceramic phosphor plate obtained by sintering at least one type of phosphor using a glass composition for glass composition and a glass frit obtained by vitrifying the glass composition for a photoconversion device as a matrix This composition is suppressed and the porosity of the phosphor plate is reduced by controlling the particle size of the glass frit, thereby minimizing whitening. In addition, it is possible to secure the reliability of LED lighting and vehicle packages that require long-term reliability and high output.

1 is a photograph taken by observing (a) and (b) after (a) and after (b) the reliability evaluation of a conventional phosphor plate at high temperature and high humidity (85° C./85%).
2 is a photograph taken by observing the surface of a conventional phosphor plate after injection of reliability evaluation at high temperature and high humidity (85° C./85%) with a scanning electron microscope (SEM).
3 is a schematic diagram illustrating a mechanism for causing whitening in a conventional phosphor plate.
4 is a photograph taken by observing pores formed on the surface of a conventional phosphor plate with a scanning electron microscope (SEM).
5 is a cross-sectional view of an integrating sphere for measuring optical characteristics of a ceramic phosphor plate according to the present embodiment.
6 is a photograph of the surface of the phosphor plate prepared in this example observed with an optical microscope (a) and an electron scanning microscope (SEM) (b).
7 is a photograph of a surface of a phosphor plate prepared in Comparative Example observed with an optical microscope (a) and an electron scanning microscope (SEM) (b).
8 is a photograph of a surface of a phosphor plate prepared in Comparative Example observed with an optical microscope (a) and an electron scanning microscope (SEM) (b).
9 is a graph plotting the pH measured in the ion dissolution test of this Example and Comparative Example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understood that the embodiments described in the present specification and the configurations shown in the drawings are only preferred embodiments of the present invention, and there may be various equivalents and modified examples that can replace them at the time of application. . In addition, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention in describing the operation principle of the preferred embodiment of the present invention in detail, the detailed description thereof will be omitted. The terms described below are terms defined in consideration of functions in the present invention, and the meaning of each term should be interpreted based on the contents throughout the present specification.

The glass composition for a photoconversion device according to the present embodiment includes an oxide mixture consisting of silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ) and zinc oxide (ZnO); And an oxide containing a metal of Group I or II, wherein the content of the boron oxide and the oxide containing the metal of the Group I or II is 35% by weight or less of the total composition.

The oxide mixture composed of the silicon oxide, the boron oxide, and the zinc oxide is a material that forms the most basic structure when glass is manufactured by vitrifying a glass composition. Among the oxides forming the glass, the network former ) Or belong to the mesh forming oxide. The oxide mixture is the most basic component of glass, and this composition alone can produce a three-component glass. In the oxide mixture, the ratio of the silicon oxide, the boron oxide, and the zinc oxide may be 1:1.5:4 to 1:2.5:5. However, in the oxide mixture, the silicon oxide and the zinc oxide do not affect the whitening phenomenon of the phosphor plate. On the other hand, the content of boron oxide may act as a major factor causing whitening. Therefore, the content of boron oxide may be less than 25% by weight of the total glass composition.

In this embodiment, the oxide containing a metal of Group I or II is sodium oxide (Na ₂ O), potassium oxide (K ₂ O), lithium oxide (Li ₂ O), barium oxide (BaO), strontium oxide ( SrO) or calcium oxide (CaO), and may be added by mixing two or more. The oxide containing a metal of Group I or II serves to lower the glass transition temperature (T _g ) of the glass obtained after the composition is vitrified. As the glass transition temperature (T _g ) is lower, the sintering temperature may be lowered when manufacturing the phosphor plate. However, the oxide containing a metal of the Group I or II may act as a factor that inhibits vitrification or causes whitening as the amount of oxide increases. Therefore, it is preferable to control the content of the oxide containing a metal of Group I or II to less than 15% by weight. In addition, the total amount of the oxide containing the metal of the Group I or II and the boron oxide acting as a factor of the whitening phenomenon may be less than 35% by weight of the total glass composition.

The ceramic phosphor plate according to another aspect of the present embodiment has a glass frit obtained by vitrifying the above-described glass composition as a matrix, and includes at least one type of phosphor.

The glass frit is obtained by vitrifying and pulverizing a glass composition comprising an oxide mixture composed of silicon oxide, boron oxide, and zinc oxide and an oxide containing at least one metal of Group I or II.

The glass frit comprises an oxide mixture composed of silicon oxide, zinc oxide and boron oxide, at least one carbonate compound containing an alkali metal, and the glass composition containing aluminum oxide in a ball mill for 40 hours. After mixing for 50 to 50 hours, it is put into a melting furnace. It can be melted by controlling the melting temperature according to the composition of the glass composition. At this time, the melting temperature may be 1300°C to 1600°C, and glass may be manufactured according to a conventional glass manufacturing process. The raw material contained in the glass composition is melted by selecting a temperature at which it can be homogeneously dissolved. At this time, if the temperature is increased above 1600°C, there is a concern that volatile components may increase. The melt is poured into twin rolls to perform quenching to prepare a glass cullet. The glass cullet is pulverized to prepare a glass frit.

There are dry and wet grinding methods, and dry grinding includes methods such as ball mill and vibration mill. Ceramic balls used in the ball mill are generally aluminum oxide (Al ₂ O ₃ ) or zirconium oxide (ZrO ₂ ). Because the vibrating mill uses vibrating motion, the impact on the pulverized material is great. Wet grinding is a method of grinding by stirring the ground material and balls in a liquid. Compared with dry grinding, fine grinding is possible. In addition to the ball mill, a medium stirring mill and a bead mill are used. The bead mill is a pulverizer using ceramic beads having a diameter of 0.5 mm to 2.0 mm and having high wear resistance. The liquid used for wet grinding may be an organic solvent such as water or ethanol. In the case of glass having high water resistance, water is mainly used, and when water is used, an organic solvent can be used if there is a concern about changes in components.

The glass frit according to the present embodiment may have an average particle diameter of 1 μm to 20 μm, and preferably 2 μm to 12 μm. As shown in FIG. 6, when the particle diameter of the glass frit is reduced, the internal porosity after sintering is reduced, which is advantageous for improving optical properties. When the particle diameter of the glass frit exceeds 20 μm, there is a concern that a number of pores may be formed when the glass frit is later mixed with a phosphor and sintered. On the other hand, when the particle diameter of the organic frit is less than 1 μm, there is a concern that when mixed with the phosphor, it cannot be sufficiently dispersed and thus the phosphor cannot be sufficiently passivated, and the degree of contamination increases as the milling time increases It becomes difficult to maintain whiteness.

The ceramic phosphor may be one of yellow, green, or red phosphors depending on the required optical characteristics, color of lighting, and application, and may be two or more types of phosphors that excite light of different wavelengths as needed. . The ceramic phosphor is yttrium-aluminum-garnet (YAG), ruthenium-aluminum-garnet (Lutetium aluminum garnet; LuAG), nitride, sulfide, or silicate. You can use

The ceramic phosphor is mixed in an amount of 1% to 15% by weight based on the glass frit. At this time, the amount of the phosphor mixture may be changed in a small amount according to the transmittance and color difference after sintering. In addition, the content of the phosphor is also changed according to the change in thickness, and when the thickness is increased, the phosphor can be added by reducing the amount.

The mixture of the glass frit and the ceramic phosphor is put into a stainless use steel (SUS) mold so as to have a plate or disc shape, and uniaxial compression is performed. At this time, compression is performed at 7 tones for 5 minutes. The compressed mixture of inorganic phosphor-glass powder is placed in a sintering furnace to perform sintering. In this case, the temperature and time for firing may be adjusted according to the glass transition temperature (Tg) of the inorganic phosphor and the glass powder.

The sintered ceramic phosphor plate may be further subjected to surface polishing in order to adjust the thickness and adjust the surface roughness to suit the characteristics required in the present embodiment. In this case, polishing is performed so that the thickness of the ceramic phosphor plate is 200 μm to 1000 μm, and the surface roughness is 0.1 μm to 0.3 μm.

5 is a cross-sectional view of an integrating sphere for measuring optical characteristics of a ceramic phosphor plate according to the present embodiment.

Referring to FIG. 5, the integrating sphere has an internal luminance constant at any angle, and captures all of the light reflected from the sample surface so that it is distributed evenly on the surface of the integrating sphere. Special paint or polytetrafluoroethylene (PTFE, polytetrafluoroethylene) is used as a coating material for the inner wall of the integrating sphere. Be careful not to contaminate the interior. In the case of spectral transmittance, 100% of light transmitted without a sample is set, and 0% is set when the light is completely blocked by an opaque object such as an iron plate. When the dispersion effect in the transmissive material is large among the transmissive colors, it is preferable to measure using an integrating sphere.

The integrating sphere includes the ceramic phosphor plate 110 described above. The ceramic phosphor plate 110 is provided to be spaced apart from the light source 120. A distance separated from the light source may be 10 mm to 20 mm. The separation distance may preferably be 12 mm to 18 mm. When the separation distance exceeds 20 mm, there is a concern that light extraction may not be sufficiently performed. On the other hand, when the separation distance is less than 10 mm, there is a concern that the ceramic phosphor 110 may cause thermal deformation due to heat generated from the light source 120.

The integrating sphere includes a housing 130 having a shape extending upward from the bottom surface with the light source 120 as the center. As the light source 120, as an optical device that emits light, a solid light emitting device may be applied as an example. The solid light emitting device may be any one selected from LED, OLED, LD (laser diode), Laser, VCSEL. A ceramic phosphor plate 110 is provided on the upper end of the housing 130 and disposed to be spaced apart from the light source 120. As described above, the ceramic phosphor plate 110 includes a matrix made of glass frit and a ceramic phosphor dispersed in the matrix. The inside of the housing 132 may be filled with a material having a refractive index higher than or equal to that of the ceramic phosphor plate 110.

Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended to aid understanding of the present invention, and the scope of the present invention is not limited to these examples in any sense.

[ Manufacturing example ] Glass Fritted Produce

After weighing the oxide and carbonate compound materials according to the composition shown in Table 1 below, they were added to a ball mill and mixed for 48 hours. The mixed powder was put in a platinum crucible and melted at 1300° C. for 30 minutes, and then the melt was poured into twin rollers to perform quenching to obtain a glass cullet. The glass cullet was put into a ball mill again and pulverized so that the particle diameter was less than 15 µm to obtain a glass frit.

[ Example ] Preparation of phosphor plate

In each of the glass frits prepared in Preparation Example, 7 wt% of a 530 to 560 nm LuAG phosphor and 2 wt% of a 690 to 630 nm nitride phosphor were added to a ball mill and sufficiently mixed. The obtained mixture was put into a suspension mold (molded product thickness of 1000 μm) and uniaxial compression was performed at 5 tons for 5 minutes to obtain a compression molded product. The compression molded product was calcined in a firing furnace at a temperature of 630° C. for 30 minutes. Thereafter, mirror processing was performed so that the surface roughness was 0.2 µm to obtain a phosphor plate.

[ Comparative example ]

In the same manner as in Preparation Examples and Examples, a phosphor plate having the composition shown in Table 1 was obtained.

Example Comparative Example 1 Comparative Example 2 Comparative Example 3 SiO ₂ 12 13 14 13 B ₂ O ₃ 24 23 25 24 Na ₂ O 4 7 7 10 ZnO 56 46 48 48 K ₂ O 0 11 6 0 Li ₂ O ₃ 4 0 0 0 CaO 0 0 0 5 Sum 100 100 100 100 Sum of whitening elements 32 41 38 39

※ Unit is% by weight

[evaluation]

1. Accelerated life evaluation ( ALT : Accelerated Life Test )

The phosphor plates prepared in Examples, Comparative Examples 1 and 2 were allowed to stand for 1000 hours in a high temperature and high humidity (85° C., 85% humidity) environment according to the LED reliability regulations, and then observed with an optical microscope and an electron scanning microscope (SEM), respectively. The results are shown in Table 2 below.

Example Comparative Example 1 Comparative Example 2 Baekhwado 0 5 3 Porosity (%) 1.12 5.55 3.66 Optical micrograph Fig. 6(a) Fig. 7(a) Fig. 8(a) SEM photo Fig. 6(b) Fig. 7(b) Fig. 8(b)

※ The degree of whitening increases from 0 to 5, the more severe the whitening phenomenon.

2. Ion elution observation

The phosphor plates prepared in Example, Comparative Example 1 and Comparative Example 2 were respectively added to distilled water at 85° C. and allowed to stand, and the pH was measured, and the results are shown in FIG. 9.

3. ICP analysis( Inductively Coupled Plasma Spectrometry )

ICP analysis was performed with distilled water used in the ion elution observation, and the results are shown in Table 3 below.

Distilled water Example Comparative Example 1 Comparative Example 2 Li 0.02 0.11 0.93 0.36 Ca 0.09 10.90 7.48 10.66 Na 0.57 10.22 34.08 10.71 B 0.45 2.66 27.23 4.07 K 0.35 3.68 6.13 6.57 Si 0.37 4.77 6.96 4.09 Zn - - - - B, Na, Li, K
Total amount of eluted ions
(Mg/kg) 1.39 16.66 68.36 21.71

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain the technical idea, and the protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto are It should be construed as being included in the scope of the present invention.

110: ceramic phosphor plate
120: light source
130: housing
W _T , W _B : width
H: height

Claims (7)

An oxide mixture consisting of silicon oxide (SiO2), boron oxide (B2O3) and zinc oxide (ZnO); And
Including any one or more oxides of oxides containing a metal of Group I or II,
In the oxide mixture, the ratio by weight of the silicon oxide, the boron oxide, and the zinc oxide is 1:1.5:4 to 1:2.5:5,
The content of boron oxide is more than 0% by weight and less than 25% by weight of the total composition, and the oxide containing a metal of Group I or II is added in an amount of more than 0% by weight and less than 15% by weight of the total composition. Glass composition for devices.
The method according to claim 1,
The oxide containing a metal of the Group I or II,
Selected from the group consisting of sodium oxide (Na ₂ O), potassium oxide (K ₂ O), lithium oxide (Li ₂ O), barium oxide (BaO), strontium oxide (SrO), calcium oxide (CaO) and mixtures thereof A glass composition for a photoconversion device that is at least one oxide of.
delete delete In a ceramic phosphor plate comprising, as a matrix, a glass frit obtained by vitrifying the glass composition for a photoconversion device of claim 1 or 2,
A ceramic phosphor plate obtained by sintering the glass frit and at least one phosphor and having a porosity of less than 2%.
The method of claim 5,
The glass frit,
Ceramic phosphor plate having a particle diameter of 1 μm to 20 μm.
The method of claim 5,
The phosphor,
Yttrium-aluminum-garnet (Yttrium Aluminum Garnet; YAG) system, ruthenium-aluminium-garnet (Lutetium aluminum garnet; LuAG) system, nitride (nitride) system, sulfide (sulfide) system selected from the group consisting of silicate (silicate) system Ceramic phosphor plate that is at least one or more phosphors.

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