JP2010083704A - Phosphor-containing glass and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphor-containing glass capable of preventing deterioration of phosphor-particles when glass and phosphor-particles are heated in manufacturing, processing or the like. <P>SOLUTION: In the phosphor-containing glass for wavelength conversion, phosphor-particles 7, a coating material 71 coating the surfaces of the phosphor-particles 7 and a glass material 6 containing the phosphor-particles 7 coated with the coating material 71 are contained, and the coating material 71 is made to have heat resistance of glass transition temperature of the glass material 6 or higher. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a phosphor-containing glass and a method for producing the same.

Conventionally, in a silicate phosphor applied to a fluorescent lamp, a technique of coating the surface of phosphor particles with a boron compound is known (see, for example, Patent Document 1).
In addition, in a phosphor used in an EL (electroluminescence) lamp, a technique is known in which the surface of a phosphor particle is coated with a water-resistant inorganic material, and then the surface of the coating material is melted and solidified (for example, Patent Document 2).
In addition, as a method for coating the surface of the phosphor particles, the phosphor particles are dispersed in an organic solvent, and the surface of the phosphor particles is coated with a metal oxide by using a hydrolysis reaction of one or more metal alcoholates, or A technique for coating with a metal coating oxide is known (see, for example, Patent Document 3).
Further, it has been proposed that phosphor particles are contained in glass for sealing a light emitting element (see, for example, Patent Document 4).
Japanese Patent Laid-Open No. 2-91188 JP-A-4-178486 Japanese Laid-Open Patent Publication No. 4-279593 JP 2008-71837 A

  By the way, as described in Patent Document 4, when phosphor particles are contained in glass, the phosphor particles are deteriorated by the heat applied at the time of manufacturing or processing the phosphor-containing glass, and the light emission characteristics are changed. There is a fear.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress the deterioration of the phosphor particles when the glass and the phosphor particles are heated at the time of manufacturing and processing. An object of the present invention is to provide a phosphor-containing glass that can be manufactured and a method for producing the same.

  In order to achieve the above object, the present invention has phosphor particles, a covering material that covers the surface of the phosphor particles, and a glass material that includes the phosphor particles whose surface is covered by the covering material. The coating material is provided with phosphor-containing glass having heat resistance equal to or higher than the glass transition temperature of the glass material.

  In the phosphor-containing glass, it is preferable that the covering material prevents solid solution of the phosphor particles and the glass material at a glass transition temperature of the glass material.

  In the phosphor-containing glass, the phosphor particles may be a silicate phosphor, and the glass material may be a silicate glass.

  In order to achieve the object, in the present invention, a coating step of covering the surface of the phosphor particles with a coating material, a phosphor powder composed of the phosphor particles whose surface is covered with the coating material, and glass powder are mixed. A method for producing a phosphor-containing glass having a heat resistance equal to or higher than a firing temperature in the firing step. The

  ADVANTAGE OF THE INVENTION According to this invention, when glass and fluorescent substance are heated at the time of manufacture, a process, etc., degradation of fluorescent substance can be suppressed.

  1 to 5 show an embodiment of the present invention, and FIG. 1 is a schematic longitudinal sectional view of a light emitting device.

  As shown in FIG. 1, the light emitting device 1 includes an LED element 2 made of a flip-chip GaN-based semiconductor material, a mounting substrate 3 on which the LED element 2 is mounted, and a tungsten (W)- It has a circuit pattern 4 composed of nickel (Ni) -gold (Au), and a glass sealing portion 6 that seals the LED element 2 and is bonded to the mounting substrate 3 and includes phosphor particles 7. Further, a hollow portion 5 in which glass does not surround is formed between the LED element 2 and the mounting substrate 3. In the present embodiment, the mounting substrate 3 and the circuit pattern 4 constitute a mounting portion for mounting the LED element 2 and supplying power to the LED element 2.

The LED element 2 as a light emitting element is obtained by epitaxially growing a group III nitride semiconductor on the surface of a growth substrate made of sapphire (Al ₂ O ₃ ), whereby a buffer layer, an n-type layer, an MQW layer, p The mold layer is formed in this order. The LED element 2 is epitaxially grown at 700 ° C. or higher, and has a heat resistant temperature of 600 ° C. or higher, which is stable with respect to a processing temperature in a sealing process using a low-melting-point heat-sealing glass described later. The LED element 2 has a p-side electrode 21 provided on the surface of the p-type layer, and an n-side electrode formed on the n-type layer exposed by etching a part from the p-type layer to the n-type layer. 22. Bumps 23 are respectively formed on the p-side electrode 21 and the n-side electrode 22.

The LED element 2 has a thickness of 100 μm and is formed in a 300 μm square, and has a thermal expansion coefficient of 7 × 10 ⁻⁶ / ° C. Here, although the thermal expansion coefficient of the GaN layer of the LED element 2 is 5 × 10 ⁻⁶ / ° C., the thermal expansion coefficient of the growth substrate made of sapphire occupying most is 7 × 10 ⁻⁶ / ° C., The thermal expansion coefficient of the LED element 2 body is equal to the thermal expansion coefficient of the growth substrate. In addition, in each figure, in order to clarify the structure of each part of the LED element 2, each part is shown by the size different from an actual size.

The mounting substrate 3 is made of a polycrystalline sintered material of alumina (Al ₂ O ₃ ), has a thickness of 0.25 mm and a 1.0 mm square, and has a thermal expansion coefficient of 7 × 10 ⁻⁶ / ° C. . As shown in FIG. 1, the circuit pattern 4 of the mounting substrate 3 includes a surface pattern 41 formed on the substrate surface and electrically connected to the LED element 2, and a back surface formed on the substrate back surface and connectable to an external terminal. And a pattern 42. The front surface pattern 41 and the back surface pattern 42 are electrically connected by a via pattern 43 provided in a via hole penetrating the mounting substrate 3 in the thickness direction.

The glass sealing portion 6 is made of silicate glass in which the phosphor particles 7 are uniformly dispersed. In the present embodiment, ZnO—B ₂ O ₃ —SiO ₂ —Nb ₂ O ₅ —Na ₂ O—Li ₂ O heat-sealing glass is used as the silicate glass. The composition of the glass is not limited to this. For example, the heat-sealing glass may not contain Li ₂ O, or may contain ZrO ₂ , TiO ₂ or the like as an optional component. Good. As shown in FIG. 1, the glass sealing portion 6 is formed in a rectangular parallelepiped shape on the mounting substrate 3 and has a thickness of 0.5 mm.

The side surface 6a of the glass sealing portion 6 is formed by cutting a plate glass bonded to the mounting substrate 3 by hot pressing together with the mounting substrate 3 with a dicer. Moreover, the upper surface 6b of the glass sealing part 6 is one surface of the plate glass bonded to the mounting substrate 3 by hot pressing. This heat-sealing glass has a glass transition temperature (Tg) of 490 ° C. and a yield point (At) of 520 ° C., and the glass transition temperature (Tg) is sufficiently higher than the formation temperature of the epitaxial growth layer of the LED element 2. It is low. In this embodiment, the glass transition temperature (Tg) is lower by 200 ° C. or more than the formation temperature of the epitaxial growth layer. Moreover, the coefficient of thermal expansion (α) at 100 ° C. to 300 ° C. of the heat-fusible glass is 6 × 10 ⁻⁶ / ° C. When the thermal expansion coefficient (α) exceeds the glass transition temperature (Tg), a larger numerical value is obtained. As a result, the heat-sealing glass is bonded to the mounting substrate 3 at about 600 ° C. and can be hot-pressed. Moreover, the refractive index of the heat sealing | fusion glass of the glass sealing part 6 is 1.7.

  Here, the heat-sealed glass is glass that is molded in a molten state or a softened state by heating, and is different from glass that is molded by a sol-gel method. Since the sol-gel glass has a large volume change at the time of molding, cracks are likely to occur, and it is difficult to form a thick film of glass. However, the heat-fused glass can avoid this problem. Further, since the sol-gel glass generates pores, airtightness may be impaired. However, the heat-sealed glass does not cause this problem, and the LED element 2 can be accurately sealed.

FIG. 2 is an enlarged cross-sectional explanatory view of a glass sealing portion of the light emitting device.
As shown in FIG. 2, the surface of the phosphor particles 7 is covered with a covering material 71. The phosphor particles 7 are yellow phosphors that emit yellow light having a peak wavelength in a yellow region when excited by blue light emitted from the MQW layer of the LED element 2. In the present embodiment, a silicate phosphor is used as the phosphor particle 7, the average particle diameter is 6 to 20 μm, and the maximum particle diameter is 50 μm. The silicate phosphor is, for example, (Ba, Sr, Ca, Mg) ₂ SiO ₄ : Eu ²⁺ . The phosphor particles 7 may be YAG (Yttrium Aluminum Garnet) -based phosphors, YAG-based and silicate phosphors mixed at a predetermined ratio, or the like.

The covering material 71 has heat resistance equal to or higher than the glass transition temperature of the glass sealing portion 6. In the present embodiment, the covering material 71 is made of alumina (Al ₂ O ₃ ) fine particles, has a maximum particle diameter of 1 μm, and a thickness of 20 nm to 1 μm. In the present embodiment, the heat-resistant temperature of the covering material 71 is 1000 ° C. or higher. The covering material 71 may be a material other than alumina as long as it has heat resistance, and for example, silica may be used.

  In the light emitting device 1 configured as described above, when a voltage is applied to the LED element 2 through the circuit pattern 4, blue light is emitted from the LED element 2. Part of the blue light emitted from the LED element 2 is converted to yellow light by the phosphor particles 7 in the glass sealing part 6, and the other part is not wavelength-converted by the phosphor particles 7 and the glass sealing part 6. To the outside. As a result, the light emitted from the glass sealing portion 6 has peak wavelengths in the yellow region and the blue region, and as a result, white light is emitted to the outside of the apparatus.

A method for manufacturing the light emitting device 1 will be described below with reference to the process explanatory diagram of FIG.
First, the surface of the phosphor particles 7 made of a silicate phosphor having an average particle diameter of 15 μm is coated with a coating material 71 made of alumina (coating step). In the present embodiment, alumina fine particles are attached to the surface of the phosphor particles 7 using an organic solvent, and then bonded to the phosphor particles 7 by heating.

  On the other hand, the silicate glass which is a glass material of the glass sealing part 6 is grind | pulverized, and glass powder whose average particle diameter is 30 micrometers is produced. This glass powder is mixed with a phosphor powder composed of phosphor particles 7 whose surface is covered with a covering material 71 to produce a mixed powder (mixing step). In the present embodiment, the mixed powder 10 in which the phosphor particles 7 with the covering material 71 are uniformly dispersed in the glass powder is produced.

  Subsequently, the phosphor-containing glass is manufactured by baking the mixed powder 10 at the glass transition temperature (baking step). Specifically, after melting the mixed powder 10 generated in the mixing step while applying a load, the mixed powder is solidified to generate a phosphor-dispersed glass 11 as a phosphor-containing glass. Here, since the covering material 71 has heat resistance equal to or higher than the firing temperature, which is the glass transition temperature, the glass material and the phosphor particles 7 do not come into contact with each other in the firing step, and the coating material 71 is fluorescent in the firing step. The body particles 7 are protected by the covering material 71, and the deterioration of the phosphor particles 7 is suppressed. In particular, in this embodiment, since the glass material is silicate glass and the phosphor particles 7 are silicate phosphors, the glass material and the phosphor particles 7 if the coating material 71 is not present. Will dissolve and the characteristics of the phosphor will be impaired.

  4A and 4B are explanatory views showing the processing state of the phosphor-dispersed glass, in which FIG. 4A shows a processing device that generates the phosphor-dispersed glass from the mixed powder, and FIG. 4B shows the phosphor-dispersed glass generated from the mixed powder. (C) shows a state in which the obtained phosphor-dispersed glass is sliced.

More specifically, as shown in FIG. 4A, a cylindrical side frame 81 surrounding a predetermined area on the lower base 80 is provided on the flat upper surface 80a of the lower base 80, and a concave portion 82 opened upward. Form. The recess 82 has the same cross section in the vertical direction, and a lower portion 83 a of a load jig 83 formed corresponding to the cross-sectional shape of the recess 82 can move up and down in the recess 82. After the mixed powder 10 is put into the concave portion 82, a load jig 83 for pressurizing the concave portion 82 is set. Then, the atmospheric air is decompressed to 7.6 Torr and heated to 650 ° C., and a pressure of 20 kg / cm ² is applied to the mixed powder 10 using the load jig 83 and dissolved.

  Thereafter, the melted mixed powder 10 is cooled and solidified, so that the phosphor with the covering material 71 is produced without causing residual bubbles or white turbidity of an optically affecting size as shown in FIG. 4B. A phosphor-dispersed glass 11 in which particles 7 are dispersed can be obtained. The produced phosphor-dispersed glass 11 is sliced so as to correspond to the thickness of the glass sealing portion 6 and processed into a plate shape as shown in FIG. In this embodiment, the thickness of the glass sealing part 6 is 0.5 mm.

  On the other hand, separately from the phosphor-dispersed glass 11, a mounting substrate 3 in which via holes are formed is prepared, and W paste is screen-printed on the surface of the mounting substrate 3 according to a circuit pattern. Next, the mounting substrate 3 on which the W paste is printed is heat-treated at 1000 ° C. or more to burn W on the mounting substrate 3, and further, Ni plating or Au plating is performed on W to form a circuit pattern 4 (pattern) Forming step).

  Next, the plurality of LED elements 2 are electrically joined to the surface pattern 41 of the circuit pattern 4 of the mounting substrate 3 by the bumps 23 (element mounting process). In the present embodiment, a total of three bump bondings are performed: two points on the p side and one point on the n side.

  Then, the mounting substrate 3 on which each LED element 2 is mounted is set in the lower mold 91 and the plate-like phosphor-dispersed glass 30 is set in the upper mold 92. A heater is disposed in each of the lower mold 91 and the upper mold 92, and the temperatures of the molds 91 and 92 are independently adjusted. Next, as shown in FIG. 5, the phosphor-dispersed glass 11 is placed on the mounting surface of the substantially flat mounting substrate 3, the lower mold 91 and the upper mold 92 are pressurized, and hot pressing is performed in a nitrogen atmosphere. . In the present embodiment, the temperature of hot pressing is 600 ° C., which is the range of the heat resistance temperature of the covering material 71. Accordingly, since the covering material 71 has heat resistance equal to or higher than the processing temperature at the time of hot pressing, the glass material and the phosphor particles 7 do not come into contact at the time of hot pressing, and the phosphor particles 7 are covered. It is protected by the material 71 and the deterioration of the phosphor particles 7 is suppressed.

As a result, the phosphor-dispersed glass 11 is fused to the mounting substrate 3 on which the LED elements 2 are mounted, and the LED elements 2 are sealed on the mounting substrate 3 by the phosphor-dispersed glass 11 (glass sealing step). Here, FIG. 5 is a schematic explanatory view showing a state of hot pressing. In the present embodiment, the processing was performed at a pressure of about ²⁰ to 40 kgf / cm ² . Here, the hot pressing process may be performed in an inert atmosphere with respect to each member, and may be performed in, for example, a vacuum in addition to the nitrogen atmosphere.

  Here, in order to shorten the cycle time of the hot press process, a preheating stage is provided before pressing to preheat the glass sealing part 6, or a slow cooling stage is provided after pressing to cool the glass sealing part 6. May be controlled. Moreover, it is also possible to press in a preheating stage and a slow cooling stage, and the process at the time of a hot press process can be changed suitably.

  Through the above steps, the intermediate body 12 as shown in FIG. 5 in a state where the plurality of light emitting devices 1 are connected in the lateral direction is manufactured. Thereafter, the mounting substrate 3 integrated with the glass sealing portion 6 is set on a dicer and diced so as to separate the LED elements 2 to complete the light emitting device 1 (dicing step). Both the glass sealing part 6 and the mounting substrate 3 are cut by a dicer, so that the side surfaces of the mounting substrate 3 and the glass sealing part 6 are flush with each other.

  As described above, since the covering material 71 has heat resistance equal to or higher than the glass transition temperature, the phosphor particles are produced during the production of the phosphor-containing glass and during the sealing process of the LED element 2 using the phosphor-containing glass. 7 can be suppressed. In particular, in the present embodiment, since the glass material and the phosphor particles 7 have a property of being easily dissolved in each other at a glass transition temperature or higher, the coating material 71 prevents these solid solutions, and the characteristics as a phosphor. The phosphor particles 7 can be dispersed in the glass without impairing the above.

  In the above-described embodiment, the light emitting device 1 using the GaN-based semiconductor material as the LED element 2 has been described. However, the LED element is not limited to the GaN-based LED element 2, for example, a ZnSe-based or SiC-based LED element. Thus, a light emitting element made of another semiconductor material may be used.

  Moreover, in the said embodiment, although the combination of the silicate type | system | group fluorescent substance and the silicate type | system | group glass was shown, for example, a phosphoric acid type phosphor and phosphoric acid type glass, a borate type phosphor and a borate type glass etc. Even if the phosphor and the glass are made of the same inorganic material and are in other combinations that easily dissolve in the glass at a glass transition temperature or higher, the same effects as those of the above embodiment can be obtained. Furthermore, deterioration of the phosphor particles 7 can be suppressed even with a combination that hardly dissolves in solution, such as YAG phosphor and silicate glass.

  Moreover, in the said embodiment, although the light-emitting device 1 with which one LED element 2 was sealed was shown, as shown, for example in FIG. 6, the light-emitting device 101 with which several LED element 2 was sealed collectively. Of course, it is also possible. In the light emitting device 101 of FIG. 6, the three LED elements 2 are arranged in a predetermined direction (lateral direction in FIG. 6) and are electrically connected in series.

  Moreover, in the said embodiment, although the glass sealing part 6 formed what was formed in the rectangular parallelepiped shape was shown, as shown in FIG. 7, for example, the surface may be formed curved. In the light emitting device 201 of FIG. 7, a total of nine LED elements 2 are mounted on the mounting substrate 3 in three vertical and horizontal directions, and the surface 6 c of the glass sealing portion 6 is formed in a hemispherical shape.

Moreover, although the glass sealing part 6 of the said embodiment is excellent in weather resistance, there exists a possibility that the glass sealing part 6 may change in quality, when dew condensation arises with the use conditions etc. of an apparatus. For this, it is desirable to have a device configuration in which condensation does not occur. For example, as shown in FIG. 8, a transparent material 61 that covers the surface of the glass sealing portion 6 is provided to cause condensation in a high temperature state. It is possible to prevent the glass from being altered. In the light emitting device 301 of FIG. 8, silicon resin is used as the transparent material 61, and the surface of the transparent material 61 has a lens shape for collecting the light emitted from the LED element 2. As the transparent material 61, an inorganic material such as SiO ₂ or Al ₂ O ₃ can be used as a material having not only moisture resistance but also acid resistance and alkali resistance.

  Moreover, in the said embodiment, what sealed LED element 2 with fluorescent substance containing glass was shown, However, As shown in FIG. 9, you may make it use apart from LED element 2, for example. In the light emitting device 401 of FIG. 9, a face-up type LED element 402 is mounted on the bottom of a case body 403 made of resin. A pair of lead frames 404 is exposed at the bottom of the case 403, and the opening of the case 403 is closed by a plate glass 405. The plate glass 405 is made of the same material as the glass material of the above embodiment, and the phosphor particles 7 whose surface is covered with the covering material 71 are dispersed. According to the light emitting device 401, since the LED element 402 and the plate glass 405 are spaced apart from each other, the heat generated when the LED element 402 emits light is not transferred to the plate glass 405, but is generated by the heat transferred from the LED element 402. Deterioration of the phosphor particles 7 can be suppressed.

  Furthermore, as shown in FIG. 10, phosphor-containing glass can be used as the lens 504. A light-emitting device 501 in FIG. 10 condenses a pair of lead frames 503 extending in the horizontal direction, an LED element 502 flip-chip mounted on the lead frame 503, and light emitted from the LED elements 502 fixed to the lead frame 503. A lens 504. Here, the upper surface of the tip of each lead frame 503 is formed to be recessed from the other parts, and a submount 505 is provided that is housed in each recess and spans over each lead frame 503. The submount 505 has a wiring 506 for supplying power to the LED element 502. The lens 504 has a recess 504 a that houses the LED element 502, and is mounted and fixed on the flat upper surfaces of the lead frame 503 and the submount 505.

  In the above embodiment, the element mounting substrate is made of alumina, but may be made of ceramic other than alumina. For example, a BeO, W-Cu substrate, or the like may be used as a ceramic substrate made of a high thermal conductivity material that is more excellent in thermal conductivity than alumina. Furthermore, in the said embodiment, although what used the LED element 2 as a light emitting element was shown, a light emitting element is not limited to an LED element, In addition, it can change suitably also about specific detailed structures. Of course.

FIG. 1 is a schematic longitudinal sectional view of a light emitting device showing an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional explanatory view of a glass sealing portion of the light emitting device. FIG. 3 is a process explanatory diagram. 4A and 4B are explanatory views showing the processing state of the phosphor-dispersed glass, in which FIG. 4A shows a processing device that generates the phosphor-dispersed glass from the mixed powder, and FIG. 4B shows the phosphor-dispersed glass generated from the mixed powder. (C) shows a state in which the obtained phosphor-dispersed glass is sliced. FIG. 5 is a schematic explanatory view showing the state of hot pressing. FIG. 6 is a schematic longitudinal sectional view of a light emitting device showing a modification. FIG. 7 is a schematic longitudinal sectional view of a light emitting device showing a modification. FIG. 8 is a schematic longitudinal sectional view of a light emitting device showing a modification. FIG. 9 is a schematic longitudinal sectional view of a light emitting device showing a modification. FIG. 10 is a schematic longitudinal sectional view of a light emitting device showing a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light-emitting device 2 LED element 3 Mounting board 4 Circuit pattern 5 Hollow part 6 Glass sealing part 6a Side surface 6b Upper surface 6c Surface 7 Phosphor particle 10 Mixed powder 11 Phosphor dispersion glass 12 Intermediate 21 P side electrode 22 N side electrode 23 Bump 41 Surface pattern 42 Back surface pattern 43 Via pattern 44 Heat radiation pattern 61 Transparent material 71 Cover material 80 Lower base 80a Upper surface 81 Side frame 82 Recess 83 Load jig 83a Lower portion 91 Lower mold 92 Upper mold 101 Light emitting device 201 Light emitting device 301 Light emitting Device 401 Light-emitting device 402 LED element 403 Case body 404 Lead frame 405 Plate glass 501 Light-emitting device 502 LED element 503 Lead frame 504 Lens 504a Concave portion 505 Submount 506 Wiring

Claims (4)

Phosphor particles;
A covering material covering the surface of the phosphor particles;
A glass material containing the phosphor particles whose surface is covered with the covering material,
The said coating | covering material is fluorescent substance containing glass which has heat resistance more than the glass transition temperature of the said glass material.   The phosphor-containing glass according to claim 1, wherein the coating material prevents solid solution of the phosphor particles and the glass material at a glass transition temperature of the glass material. The phosphor particles are silicate phosphors,
The phosphor-containing glass according to claim 2, wherein the glass material is silicate glass. A coating step of covering the surface of the phosphor particles with a coating material;
A mixing step of producing a mixed powder by mixing phosphor powder composed of the phosphor particles whose surface is covered with the coating material and glass powder;
A firing step of firing the mixed powder,
The said coating | covering material is a manufacturing method of the fluorescent substance containing glass which has heat resistance more than the calcination temperature in the said baking process.

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