KR20150091614A - Glass composition for photo-conversing medium and ceramic phosphor plate including the same - Google Patents

Abstract

An embodiment of the present invention relates to a photo-converting device glass composition and a ceramic fluorescent plate. The photo-converting device glass composition comprises: an oxide mixture consisting of silicon oxide (SiO_2), boron oxide (B_2O_3), and zinc oxide (ZnO); and one or more oxides from oxides including metals of Group I or Group II. The content of the boron oxide and the oxides including the metals of Group I or Group II is 35 wt% or less with respect to a total composition. The ceramic fluorescent plate uses a glass frit obtained by glassifying the photo-converting device glass composition as a matrix and is obtained by sintering at least one fluorescent body.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a glass composition for a photoconversion device, and a ceramic phosphor plate comprising the same. ≪

An embodiment of the present invention relates to a glass frit in which a glass composition constituting a ceramic phosphor plate used in a photoconversion device is vitrified and a ceramic phosphor plate including the glass frit.

White LEDs are attracting attention as a high efficiency and high reliability white illumination light source, and some of them have already been provided for use as a small power small size light source. There are various ways to realize white LEDs, but the most commonly used method is a blue LED device molded with resin as a matrix together with a yellow phosphor. However, since blue light is strong in energy, it is easy to deteriorate the resin. Therefore, when the white LED having such a structure is used for a long period of time, the color tone of emitted light changes because the resin is discolored. Further, since it is molded with a resin and heat dissipation from the element is not performed well, the temperature tends to rise. There is a problem that the luminous color shifts to the yellow side due to such temperature.

To solve this problem, a phosphor plate using a ceramic sintered body as a matrix material of a phosphor has been applied. The phosphor used for such a phosphor plate is limited to an oxide phosphor, particularly a phosphor of Yttrium Aluminum Garnet (YAG) type. When using only an oxide phosphor, it is difficult to realize various color coordinates and color temperature. Further, when only an oxide phosphor such as YAG is applied, the heat resistance temperature is required to be 800 DEG C or more, so that the composition of the glass does not need to be complicated. However, in order to realize various color temperatures, an appropriate amount of red phosphor and yellow phosphor must be mixed and used. For this reason, since these phosphors are weak against heat, in order to lower the sintering temperature, an alkali metal or an alkaline earth metal is added to the glass composition, The composition needs to be adjusted.

However, due to the nature of the material, the glass permeability may decrease due to the reaction between moisture and glass composition during long-term use (see Figs. 1 and 2, %) Prior to the reliability evaluation, Fig. 1 (b) shows the high temperature and high humidity reliability evaluation after input. The whitening phenomenon is known to affect the whitening phenomenon of B, Na and Li elements, but it is known that the Na element easily forms hydrates. Figure 3 shows the mechanism by which whitening occurs due to formation of hydrates due to moisture and free elements, especially sodium. In this way, a step of about 5 to 8 mu m is generated on the surface due to corrosion and hydrate formation (right picture of Fig. 2).

Another factor accelerating the whitening phenomenon is the pore inside the phosphor plate. FIG. 3 is a scanning electron microscope (SEM) photograph of the pores generated on the surface. When a large amount of pores are generated, the reaction area increases due to an increase in the surface area, thereby accelerating the whitening phenomenon.

SUMMARY OF THE INVENTION An embodiment of the present invention is directed to solve the problems of the prior art as described above, and it is an object of the present invention to provide an oxide mixture composed of silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ) and zinc oxide (ZnO) And an oxide comprising a Group I or Group II metal, wherein the content of the oxide comprising boron oxide and the Group I or Group II metal in the total composition is not more than 35 wt% And to provide a ceramic phosphor plate obtained by sintering at least one kind of phosphor with a glass frit obtained by vitrifying the glass composition for a photoconversion element as a matrix.

In order to achieve the above object, an oxide mixture comprising silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ), and zinc oxide (ZnO); And an oxide comprising a Group I or Group II metal, wherein the content of the oxide comprising boron oxide and the Group I or Group II metal in the total composition is not more than 35 wt% ≪ / RTI >

According to another aspect of the present invention, there is provided a ceramic phosphor plate obtained by sintering at least one kind of phosphor with a glass frit obtained by vitrifying the glass composition for a photoconversion device as a matrix.

According to an embodiment, an oxide mixture composed of silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ) and zinc oxide (ZnO); And an oxide comprising a Group I or Group II metal, wherein the content of the oxide comprising boron oxide and the Group I or Group II metal in the total composition is not more than 35 wt% And a glass frit obtained by vitrification of the glass composition for a photoconversion device is used as a matrix and a ceramic phosphor plate obtained by sintering at least one kind of phosphor is provided, And the porosity of the phosphor plate is reduced by controlling the grain size of the glass frit, thereby minimizing the whitening phenomenon. In addition, it is possible to secure the reliability of the LED lighting and vehicle package requiring long-term reliability and high output.

FIG. 1 is a photograph of a conventional phosphor plate taken at (a) and (b) before high-temperature and high-humidity (85 ° C./85%) reliability evaluation.
FIG. 2 is a photograph of a surface of a conventional phosphor plate after a high-temperature and high-humidity (85 ° C./85%) reliability evaluation is put on and observed with a scanning electron microscope (SEM).
3 is a schematic view illustrating a mechanism for causing whitening in a conventional phosphor plate.
FIG. 4 is a photograph of a pore formed on the surface of a conventional phosphor plate observed by a scanning electron microscope (SEM).
5 is a cross-sectional view of an integrating sphere for measuring optical characteristics of the ceramic phosphor plate according to the present embodiment.
Fig. 6 is a photograph of the surface of the phosphor plate produced in the present example observed with an optical microscope (a) and a scanning electron microscope (SEM) (b).
Fig. 7 is a photograph of the surface of the phosphor plate produced in the comparative example with an optical microscope (a) and a scanning electron microscope (SEM) (b).
8 is a photograph of the surface of the phosphor plate produced in the comparative example observed with an optical microscope (a) and a scanning electron microscope (SEM) (b).
FIG. 9 is a graph plotting the pH measured in the ion dissolution test of this example and the 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. It should be understood, however, that the embodiments described in the present specification and the constitutions shown in the drawings are only a preferred embodiment of the present invention, and that various equivalents and modifications can be made at the time of filing of the present application . DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention. The following terms are defined in consideration of the functions of the present invention, and the meaning of each term should be interpreted based on the contents throughout this specification.

The glass composition for a photoconversion device according to this embodiment is an oxide mixture composed of silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ), and zinc oxide (ZnO); And an oxide comprising a Group I or Group II metal, wherein the content of the oxide comprising boron oxide and the Group I or Group II metal is no more than 35 wt% of the total composition.

The oxide mixture of silicon oxide, boron oxide, and zinc oxide is the most basic structure when glass is made by vitrifying the glass composition, and among the oxides forming the glass, ) Or a mesh-forming oxide. The oxide mixture is the most basic component of glass, and a three-component glass can be produced with only this composition. 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, the silicon oxide and the zinc oxide in the oxide mixture do not affect the whitening phenomenon of the phosphor plate. On the other hand, the content of the boron oxide may act as a main cause of whitening. Thus, the content of boron oxide may be less than 25% by weight of the total glass composition.

In this embodiment, the oxide comprising the Group I or Group II metal is 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) or calcium oxide (CaO), or two or more of them may be mixed and added. The oxides containing the Group I or Group II metals serve to lower the glass transition temperature (T _g ) of the glass obtained after the composition is vitrified. The glass transition temperature is low (T _g) can lower the sintering temperature during manufacturing the phosphor plate. However, as the amount of the metal oxide containing Group I or Group II metal is increased, it may inhibit vitrification or cause bleaching phenomenon. Therefore, the content of the oxide containing the Group I or Group II metal is preferably controlled to less than 15% by weight. In addition, the sum of the contents of the oxides containing the Group I or Group II metals and the content of the boron oxide serving as a factor of whitening may be less than 35% by weight in the total glass composition.

The ceramic phosphor plate according to another aspect of the present invention comprises at least one kind of phosphor, which is a glass frit obtained by vitrifying the above-mentioned glass composition as a matrix.

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

The glass frit is obtained by mixing the glass composition containing an oxide mixture of silicon oxide, zinc oxide and boron oxide, at least one carbonate compound containing an alkali metal and aluminum oxide in a ball mill for 40 hours To 50 hours, and then the mixture is introduced into the melting furnace. The melting temperature can be controlled according to the composition of the glass composition. The melting temperature may be 1300 ° C to 1600 ° C, and glass may be manufactured according to a conventional glass manufacturing process. The temperature at which the raw materials contained in the glass composition can be homogeneously dissolved is selected and melted. At this time, if the temperature exceeds 1600 DEG C, the volatile components may increase. The melt is poured into a twin roll to prepare a glass cullet. The glass cullet is crushed to prepare a glass frit.

There are dry and wet grinding, and ball mill and vibrating mill are used for dry grinding. The ceramic balls used for the ball mill are generally aluminum oxide (Al ₂ O ₃ ) or zirconium oxide (ZrO ₂ ). Since the vibrating mill uses vibrational motion, the impact on the pulverized material is large. Wet milling is a method of grinding pulverized material and balls in a liquid by stirring. Fine pulverization is possible compared with dry pulverization. In addition to ball mills, media agitating mills and bead mills are used. The bead mill is a mill using a ceramic bead having a high wear resistance of 0.5 mm to 2.0 mm in diameter. An organic solvent such as water or ethanol may be used as the liquid used for the wet pulverization. In the case of glass having a high water resistance, water is mainly used, and when water is used, an organic solvent can be used when the component is likely to fluctuate.

The glass frit according to this embodiment may have an average particle size of 1 탆 to 20 탆, and preferably 2 탆 to 12 탆. 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 the optical characteristics. If the glass frit has a particle size exceeding 20 탆, a large number of pores may be formed when the glass frit is mixed with the phosphor and sintered later. On the other hand, if the particle size of the organic frit is less than 1 mu m, it may not be sufficiently dispersed when mixed with the fluorescent material, and passivation of the fluorescent material may not be sufficiently performed. As the milling time increases, Whiteness maintenance becomes difficult.

The ceramic phosphor may be one of yellow, green, and red phosphors depending on required optical characteristics, color of illumination, application field, and may be two or more kinds of phosphors that excite light of different wavelengths, . Examples of the ceramic fluorescent substance include yttrium-aluminum garnet (YAG), ruthenium-aluminum garnet (LuAG), nitride, sulfide, or silicate Can be used.

The ceramic phosphor is mixed with the glass frit in an amount of 1 wt% to 15 wt%. At this time, the amount of phosphor mixture may be slightly changed depending on the transmittance and color difference after sintering. Also, the content of the phosphor varies depending on the change of the thickness. When the thickness is increased, the phosphor may be added in a reduced amount.

A mixture of the glass frit and the ceramic fluorescent substance is put into a stainless steel mold so as to have a plate or a disk shape to perform uniaxial compression. At this time, compression is performed for 7 minutes to 5 minutes. The compressed inorganic phosphor-glass powder mixture is fired in a firing furnace. At this time, the temperature and time for performing the firing can be controlled according to the glass transition temperature (Tg) of the inorganic phosphor and the glass powder.

The baked ceramic phosphor plate may further be subjected to surface polishing to adjust the thickness and adjust the surface roughness to meet the characteristics required in the present embodiment. At this time, the ceramic phosphor plate is polished so that the thickness of the ceramic phosphor plate is 200 탆 to 1000 탆 and the surface roughness (surface roughness) is 0.1 탆 to 0.3 탆.

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

Referring to FIG. 5, the integrating sphere has a constant internal brightness at any angle, and captures all the light reflected from the surface of the sample and distributes the light uniformly on the surface of the integrating sphere. There are special paint and polytetrafluoroethylene (PTFE) coating materials on the inner wall of the integrating sphere and care should be taken not to contaminate the interior. In the case of spectral transmittance, 100% of the light transmitted without the sample is taken as 0% when the light is completely blocked by the opaque object such as the iron plate. When the dispersion effect in the permeation color is large in the permeation color, it is preferable to measure using an integral sphere.

The integrating sphere includes the ceramic phosphor plate 110 described above. The ceramic phosphor plate 110 is spaced apart from the light source 120. The distance from the light source may be 10 mm to 20 mm. The spacing distance may preferably be 12 mm to 18 mm. If the spacing distance exceeds 20 mm, there is a possibility that light extraction may not be sufficiently performed. On the other hand, when the spacing distance is less than 10 mm, the ceramic phosphor 110 may be thermally deformed due to heat generated from the light source 120.

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

Hereinafter, the present invention will be described more specifically by way of 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 Frit  Produce

The oxide and carbonate compound materials were weighed in accordance with the composition shown in Table 1, and then charged into a ball mill and mixed for 48 hours. The mixed powder was placed in a platinum crucible and melted at 1300 ° C for 30 minutes, and then the melt was poured into a twin roller to obtain a glass cullet. The glass cullet was put into a ball mill again and pulverized to have a particle diameter of less than 15 mu m to obtain a glass frit.

[ Example ] Preparation of phosphor plate

To each of the glass frit prepared in Production Example, 7 weight% of 530 to 560 nm LuAG phosphor and 2 weight% of 690 to 630 nm nitride phosphor were put into a ball mill and sufficiently mixed. The resultant mixture was placed in a SUSMOLD (mold thickness 1000 mu m) and uniaxial compression was performed at 5 tons for 5 minutes to obtain a compact. The compression molded product was fired in a firing furnace at a temperature of 630 캜 for 30 minutes. Thereafter, mirror-surface processing was carried out so that the surface roughness became 0.2 탆 to obtain a phosphor plate.

[ Comparative Example ]

A phosphor plate having the composition shown in Table 1 below was obtained in the same manner as in Production Examples and Examples.

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 Total whitening-induced elements 32 41 38 39

※ Unit is weight%

[evaluation]

1. Accelerated Life Evaluation ( ALT : Accelerated Life Test )

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

Example Comparative Example 1 Comparative Example 2 White map 0 5 3 Porosity (%) 1.12 5.55 3.66 Optical microscope photograph 6 (a) 7 (a) 8 (a) SEM picture 6 (b) 7 (b) 8 (b)

※ The degree of whiteness increases from 0 to 5

2. Observation of ion elution

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

3. ICP  analysis( Inductively Coupled Plasma Spectrometry )

ICP analysis was performed on the 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 elution ion amount
(Mg / kg) 1.39 16.66 68.36 21.71

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. The scope of the present invention should be interpreted based on the scope of the following claims and all technical ideas within the scope of equivalents thereof are to be construed as being included in the scope of the present invention. It is to be understood that the invention is not limited thereto.

110: Ceramic phosphor plate
120: Light source
130: housing
W _T , W _B : Width
H: Height

Claims (7)

An oxide mixture composed of silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ), and zinc oxide (ZnO); And
An oxide of Group I or Group II metal,
Wherein the content of the oxide of boron oxide and the group I or II metal is 35 wt% or less in the total composition.
The method according to claim 1,
The oxide comprising the Group I or Group II metal,
And is 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) Wherein the at least one kind of oxide is at least one kind selected from the group consisting of oxides,
The method according to claim 1 or 2,
The oxide comprising the Group I or Group II metal,
To 15% by weight or less of the total composition.
The method according to claim 1,
In the oxide mixture, the ratio of the silicon oxide, the boron oxide, and the zinc oxide,
1: 1.5: 4 to 1: 2.5: 5.
A ceramic phosphor plate using a glass frit obtained by vitrifying a glass composition for a photo-conversion element according to any one of claims 1 to 4 as a matrix,
And a porosity of less than 2%, obtained by sintering the glass frit and at least one kind of phosphor.
The method of claim 5,
Wherein the glass frit comprises
A ceramic phosphor plate having a particle diameter of 1 탆 to 20 탆.
The method of claim 5,
The above-
Aluminum nitride, yttrium-aluminum garnet (YAG), ruthenium-aluminum garnet (LuAG), nitride, sulfide and silicate Wherein at least one kind of phosphor is a ceramic phosphor plate.

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