JP2020154012A - Wavelength conversion member and method for manufacturing the same, and light emitting device - Google Patents

Abstract

To provide: a wavelength conversion member in which a luminous flux value is hardly reduced and chromaticity is hardly changed after the lighting; and a light emitting device using the same.SOLUTION: A wavelength conversion member 10 comprises: a base material layer 1 made of a sintered body of glass powders 1a; and a phosphor layer 2 that is formed on one main surface of the base material layer 1 and is made of a sintered body of glass powders 2a and phosphor powders 2b. With this configuration, a decrease in a luminous flux value and a change in chromaticity after the lighting can be suppressed.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wavelength conversion member that converts the wavelength of light emitted by a light emitting diode (LED: Light Emitting Diode), a laser diode (LD: Laser Diode), or the like into another wavelength, a method for manufacturing the same, and a light emitting device. ..

In recent years, attention has been increasing to light emitting devices using LEDs and LDs as next-generation light emitting devices that replace fluorescent lamps and incandescent lamps. As an example of such a next-generation light emitting device, a light emitting device that combines an LED that emits blue light and a wavelength conversion member that absorbs a part of the light from the LED and converts it into yellow light is disclosed. .. This light emitting device emits white light, which is a composite light of blue light emitted from an LED and yellow light emitted from a wavelength conversion member. Patent Document 1 proposes a wavelength conversion member in which an inorganic phosphor powder is dispersed in a glass matrix as an example of the wavelength conversion member.

Japanese Unexamined Patent Publication No. 2003-258308

The above-mentioned light emitting device has a problem that a desired luminous flux value and chromaticity cannot be obtained because the luminous flux value tends to decrease or the chromaticity tends to change with time after lighting.

Therefore, an object of the present invention is to propose a wavelength conversion member in which a decrease in luminous flux value and a change in chromaticity are unlikely to occur after lighting, and a light emitting device using the same.

The wavelength conversion member of the present invention is formed on one main surface of a base material layer made of a glass powder sintered body and a base material layer, and is a phosphor layer made of a glass powder and a phosphor powder sintered body. It is characterized by having. With such a configuration, it is possible to suppress a decrease in the luminous flux value after lighting and a change in chromaticity. This mechanism can be explained as follows.

The conventional wavelength conversion member has a structure in which the phosphor is uniformly dispersed throughout the member. Here, since the matrix such as glass, which is a dispersion medium of the phosphor, has relatively low thermal conductivity, the heat generated by the light emission of the phosphor is difficult to conduct through the matrix, and the heat is not easily released to the outside of the member. As a result, the temperature of the wavelength conversion member becomes high, and the luminous flux value tends to decrease due to the action of the temperature quenching of the phosphor. When the luminous flux value of fluorescence decreases, the luminous flux value of the fluorescence component in the emitted light (combined light of fluorescence and transmitted excitation light) of the wavelength conversion member decreases (in other words, the luminous flux value of the transmitted excitation light is relative to the luminous flux value of fluorescence. Therefore, the chromaticity of the emitted light changes.

On the other hand, since the wavelength conversion member of the present invention has a structure in which a phosphor layer is formed on the surface of the base material layer, the fluorescence is increased by increasing the phosphor concentration in the phosphor layer while maintaining the mechanical strength of the member itself. The body layer portion can be made thinner. By doing so, the volume of the matrix occupied in the phosphor layer can be reduced and the thermal conductivity of the phosphor layer can be increased, so that the heat generated by the phosphor can be efficiently released to the outside. As a result, it is possible to effectively suppress the temperature quenching of the phosphor and suppress the decrease in the luminous flux value with time. Further, in the wavelength conversion member of the present invention, since both the base material layer and the phosphor layer are made of a sintered body containing glass powder, they are excellent in adhesion and bond strength between them, and are excellent in mechanical strength of the entire member. It also has features.

In the wavelength conversion member of the present invention, the thickness of the base material layer is preferably larger than the thickness of the phosphor layer. By doing so, it is possible to easily thin the phosphor layer and improve the phosphor concentration while maintaining the mechanical strength of the wavelength conversion member.

In the wavelength conversion member of the present invention, the thickness of the base material layer is preferably 1.1 to 10 times the thickness of the phosphor layer.

In the wavelength conversion member of the present invention, the thickness of the base material layer is preferably 45 to 900 μm.

In the wavelength conversion member of the present invention, the thickness of the phosphor layer is preferably 5 to 100 μm.

In the wavelength conversion member of the present invention, the content of the phosphor powder in the phosphor layer is preferably 1 to 80% by volume.

In the wavelength conversion member of the present invention, it is preferable that the phosphor powder is a garnet-based phosphor.

In the wavelength conversion member of the present invention, the average particle size of the phosphor powder is preferably 1 to 50 μm.

In the wavelength conversion member of the present invention, it is preferable that the glass powder in the base material layer and the glass powder in the phosphor layer have substantially the same composition. By doing so, it is possible to eliminate the difference in refractive index between the glass in the base material layer and the glass in the phosphor layer, so that the reflection loss at the interface between the two can be reduced. As a result, the emission intensity of the wavelength conversion member can be improved.

In the wavelength conversion member of the present invention, the base material layer and / or the phosphor layer may contain filler powder. By doing so, the thermal expansion coefficients of the base material layer and the phosphor layer can be easily matched, and the occurrence of warpage, cracks, etc. of the member due to the difference in thermal expansion coefficients can be suppressed. In addition, the light scattering effect of the filler powder can improve the emission intensity of the wavelength conversion member.
Further, by containing the filler powder having high thermal conductivity, the heat dissipation efficiency of the wavelength conversion member can be improved.

The method for manufacturing the wavelength conversion member is a method for producing the above-mentioned wavelength conversion member, wherein (a) a green sheet for a base material layer containing glass powder, and a phosphor layer containing glass powder and phosphor powder. Steps of preparing a green sheet for use, (b) a step of obtaining a green sheet laminate by sandwiching a green sheet for a phosphor layer between a plurality of green sheets for a base material layer, (c) firing a green sheet laminate. By doing so, a step of obtaining a sintered laminate in which a phosphor layer made of a sintered body of glass powder and a phosphor powder is sandwiched between two base material layers made of a sintered body of glass powder, and , (D) A step of removing one of the base material layers in the sintered laminate is provided. When two types of green sheets made of different materials are laminated and fired, warpage and cracks are likely to occur due to the difference in the amount of shrinkage due to the difference in the coefficient of thermal expansion of each material. On the other hand, as in the manufacturing method of the present invention, the stress of the entire member is reduced by firing with the green sheet for the phosphor layer sandwiched between a plurality of (for example, two) green sheets for the base material layer. Since it is well-balanced, warpage and cracks are less likely to occur during firing. Even in the sintered laminate after firing, there is a possibility that stress due to the difference in the coefficient of thermal expansion between the base layer and the phosphor layer remains, but the machine of the sintered laminate itself Since the target strength is relatively high, even if one of the base material layers is removed by post-processing such as grinding, warpage or cracks are unlikely to occur due to the removal.

The light emitting device of the present invention is characterized by including the above-mentioned wavelength conversion member and a light source for irradiating the wavelength conversion member with excitation light of phosphor powder.

In the light emitting device of the present invention, it is preferable that the wavelength conversion member is arranged so that the phosphor layer faces the light source. In particular, it is preferable that the phosphor layer is in contact with the light source directly or via an adhesive layer. For example, a semiconductor element such as an LED, which is a light source, uses a member having excellent thermal conductivity such as sapphire on the light emitting surface. Therefore, when the phosphor layer is arranged so as to be in contact with the light source directly or via the adhesive layer, the heat generated in the phosphor layer can be efficiently released to the outside by conducting the constituent members of the light source.

According to the present invention, it is possible to propose a wavelength conversion member in which a decrease in luminous flux value and a change in chromaticity are unlikely to occur after lighting, and a light emitting device using the same.

It is a schematic cross-sectional view which shows the wavelength conversion member which concerns on one Embodiment of this invention. It is a schematic diagram which shows the manufacturing method of the wavelength conversion member which concerns on one Embodiment of this invention. It is a schematic cross-sectional view which shows the light emitting device which used the wavelength conversion member which concerns on one Embodiment of this invention.

Hereinafter, preferred embodiments will be described. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. Further, in each drawing, members having substantially the same function may be referred to by the same reference numerals.

FIG. 1 is a schematic cross-sectional view showing a wavelength conversion member according to an embodiment of the present invention. The wavelength conversion member 10 includes a base material layer 1 and a phosphor layer 2. The phosphor layer 2 is formed on one main surface of the base material layer 1. The base material layer 1 is made of a sintered body of glass powder 1a. On the other hand, the phosphor layer 2 is composed of a sintered body of glass powder 2a and phosphor powder 2b. The planar shape of the wavelength conversion member 10 is not particularly limited, and is, for example, a rectangle such as a square or a circle. Hereinafter, each component will be described in detail.

(Base material layer)
As the glass powder 1a constituting the base material layer 1, borosilicate glass, phosphate-based glass, tin phosphate-based glass, bismuthate-based glass, tellurite-based glass and the like can be used. The borosilicate-based glass, in _{mass%, SiO 2 30~85%, Al} 2 O 3 0~30%, B 2 O 3 0~50%, Li 2 O + Na 2 O + K 2 O 0~10%, and , MgO + CaO + SrO + BaO 0 to 50%. The Suzurin salt-based glass, in mol%, SnO 30 to _90%, include those containing _P 2 O 5 _1~70%. The tellurite glass, in mol%, _TeO 2 50% or more, ZnO 0 to 45%, RO (at least one R is selected Ca, Sr and Ba) 0 to 50%, and, _La 2 _{O 3} Those containing + Gd ₂ O ₃ + Y ₂ O _{30 to} 50% can be mentioned.

The softening point of the glass powder 1a is preferably 250 ° C. to 1000 ° C., more preferably 300 ° C. to 950 ° C., and even more preferably in the range of 500 ° C. to 900 ° C. If the softening point of the glass powder 1a is too low, the mechanical strength and chemical durability of the wavelength conversion member 10 may decrease. Further, since the heat resistance of the glass powder 1a itself is low, it may be softened and deformed by the heat generated from the phosphor. On the other hand, if the softening point of the glass powder 1a is too high, the phosphor powder 2b may deteriorate in the firing step at the time of manufacturing described later, and the emission intensity of the wavelength conversion member 10 may decrease. From the viewpoint of enhancing the chemical stability and mechanical strength of the wavelength conversion member 10, the softening point of the glass powder 1a is 500 ° C. or higher, 600 ° C. or higher, 700 ° C. or higher, 800 ° C. or higher, particularly 850 ° C. or higher. Is preferable. Examples of such glass include borosilicate-based glass. However, when the softening point of the glass powder 1a becomes high, the firing temperature also becomes high, and as a result, the manufacturing cost tends to be high. Therefore, from the viewpoint of inexpensively manufacturing the wavelength conversion member 10, the softening point of the glass powder 1a is preferably 550 ° C or lower, 530 ° C or lower, 500 ° C or lower, 480 ° C or lower, and particularly preferably 460 ° C or lower. Examples of such glass include tin phosphate-based glass, bismuthate-based glass, and tellurite-based glass.

The thickness of the base material layer 1 is preferably 45 to 900 μm, 50 to 500 μm, 70 to 300 μm, and particularly preferably 90 to 200 μm. If the thickness of the base material layer 1 is too small, the mechanical strength of the wavelength conversion member 10 tends to decrease. On the other hand, if the thickness of the base material layer 1 is too large, excitation light and fluorescence are excessively absorbed or scattered inside the base material layer 1, and the emission intensity of the wavelength conversion member 10 tends to decrease.

The thickness of the base material layer 1 is preferably larger than the thickness of the phosphor layer 2. Specifically, the thickness of the base material layer 1 is 1.1 to 10 times, 1.2 to 7 times, 1.5 to 6 times, 1.8 to 5 times, particularly 3 times the thickness of the phosphor layer 2. It is preferably ~ 4 times. By doing so, the phosphor layer 2 can be easily thinned and the phosphor concentration can be improved while maintaining the mechanical strength of the wavelength conversion member 10.

In the present embodiment, the base material layer 1 is made of a powder sintered body containing only glass powder 1a, but is not limited thereto. For example, the base material layer 1 may contain other inorganic powder such as filler powder for the purpose of adjusting the coefficient of thermal expansion and obtaining a light scattering effect. By doing so, the thermal expansion coefficients of the base material layer 1 and the phosphor layer 2 can be easily matched, and the occurrence of warpage, cracks, etc. of the wavelength conversion member 10 due to the difference in thermal expansion coefficients can be suppressed. Can be done. Further, the light scattering effect of the filler powder can improve the light emission intensity of the wavelength conversion member 10. Further, by containing the filler powder having high thermal conductivity, the heat dissipation efficiency of the wavelength conversion member 10 can be improved. The filler _{powder, MgO, Al 2 O 3,} BN, AlN , and the like. Of these, MgO, Al ₂ O ₃ , and BN are preferable because they have excellent transmittance in the visible region.

(Fluorescent layer)
As the glass powder 2a constituting the phosphor layer 2, the same glass powder as that exemplified as the above glass powder 1a can be used. Here, it is preferable that the difference in refractive index between the glass powder 1a in the base material layer 1 and the glass powder 2a in the phosphor layer 2 is small. For example, the difference in refractive index (nd) between the glass powder 1a and the glass powder 2a is preferably 0.2 or less, 0.1 or less, particularly 0.05 or less, and the refractive index of both is the same. preferable. By doing so, the difference in refractive index between the sintered body portion of the glass powder 1a and the sintered body portion of the glass powder 2a can be reduced, so that the reflection loss at the interface between the two can be reduced. As a result, the emission intensity of the wavelength conversion member 10 can be improved.

Further, as will be described later, since the base material layer 1 and the phosphor layer 2 are basically produced by laminating green sheets as raw materials for each layer and firing them at the same time, the glass powder 1a and the glass powder 2a are softened. It is preferable that the difference between the points is small. For example, the difference between the softening points of the glass powder 1a and the glass powder 2a is preferably 100 ° C. or lower, 50 ° C. or lower, 30 ° C. or lower, particularly 10 ° C. or lower, and most preferably the softening points of both are the same.

From the above viewpoint, it is preferable that the glass powder 1a and the glass powder 2a have substantially the same composition. In addition, "having substantially the same composition" means having the same composition with respect to the components intentionally contained in the glass composition, and inevitably as an impurity (specifically, 0.1 mol%). No consideration is given to mixed components (at levels below).

The phosphor powder 2b is not particularly limited as long as it emits fluorescence by the incident of excitation light. Specific examples of the phosphor powder 2b include oxide phosphor powder, nitride phosphor powder, oxynitride phosphor powder, chloride phosphor powder, acidified phosphor powder, sulfide phosphor powder, and the like. One or more selected from acid sulfide phosphor powder, halide phosphor powder, chalcogenide phosphor powder, aluminate phosphor powder, halophosphate phosphor powder and garnet compound phosphor powder, etc. Be done. Of these, garnet-based phosphors are preferable because they have excellent heat resistance. When blue light is used as the excitation light, for example, a phosphor powder that emits green light, yellow light, or red light as fluorescence can be used.

The average particle size of the phosphor powder 2b is preferably 1 to 50 μm, more preferably 5 to 25 μm. If the average particle size of the phosphor powder 2b is too small, the emission intensity may decrease. On the other hand, if the average particle size of the phosphor powder 2b is too large, the emission color may become non-uniform. In addition, it tends to be difficult to reduce the thickness of the phosphor layer 2.

As the phosphor powder 2b in the phosphor layer 2, a plurality of phosphor powders having different average particle diameters may be contained. By doing so, the filling rate of the phosphor powder 2b in the phosphor layer 2 is improved, and the number of grounding points between the phosphor powders 2b is increased, so that the heat conduction path can be easily constructed. As a result, the heat dissipation efficiency of the wavelength conversion member 10 can be improved.

The content (filling rate) of the phosphor powder 2b in the phosphor layer 2 is 1 to 80% by volume, 10 to 78% by volume, 20 to 76% by volume, 30 to 74% by volume, and particularly 40 to 72% by volume. It is preferable to have. If the content of the phosphor powder 2b is too small, it is necessary to increase the thickness of the phosphor layer 2 in order to obtain a desired emission color, and as a result, the internal scattering of the phosphor layer 2 increases, resulting in light. Extraction efficiency may decrease. On the other hand, if the content of the phosphor powder 2b is too large, the density of the phosphor layer 2 tends to decrease. As a result, the number of pores in the phosphor layer 2 increases and the internal scattering increases, which may reduce the light extraction efficiency.

The thickness of the phosphor layer 2 is preferably 5 to 100 μm, 10 to 90 μm, 15 to 80 μm, and particularly preferably 20 to 70 μm. If the thickness of the phosphor layer 2 is too small, it may be difficult to obtain sufficient emission intensity. Alternatively, it is necessary to increase the content of the phosphor powder 2b in order to obtain a desired emission color, and the density of the phosphor layer 2 tends to decrease. On the other hand, if the thickness of the phosphor layer 2 is too large, the scattering and absorption of light in the phosphor layer 2 may become too large, and the emission efficiency of fluorescence and excitation light may be lowered.

In the present embodiment, the phosphor layer 2 is composed of a powder sintered body containing only glass powder 2a and phosphor powder 2b, but is not limited thereto. For example, like the base material layer 1, the phosphor layer 2 may contain other inorganic powders such as filler powder for the purpose of adjusting the coefficient of thermal expansion and obtaining a light scattering effect. By doing so, the thermal expansion coefficients of the base material layer 1 and the phosphor layer 2 can be easily matched, and the occurrence of warpage, cracks, etc. of the wavelength conversion member 10 due to the difference in thermal expansion coefficients can be suppressed. Can be done. Further, the light scattering effect of the filler powder can improve the light emission intensity of the wavelength conversion member 10. Further, by containing the filler powder having high thermal conductivity, the heat dissipation efficiency of the wavelength conversion member 10 can be improved. It should be noted that only one of the base material layer 1 and the phosphor layer 2 may contain the filler powder, or both of them may contain the filler powder.

(Manufacturing method of wavelength conversion member)
FIG. 2 is a schematic view showing a method of manufacturing a wavelength conversion member according to an embodiment of the present invention.
First, in the step (a), a green sheet 1'for a base material layer containing the glass powder 1a and a green sheet 2'for a phosphor layer containing the glass powder 2a and the phosphor powder 2b are prepared as follows.

An organic component such as a binder resin or a solvent is added to the glass powder 1a and kneaded to prepare a slurry. The prepared slurry is applied onto the supporting base material, and the doctor blades installed at predetermined intervals from the supporting base material are moved relative to the slurry to prepare a green sheet 1'for the base material layer. (Doctor blade method). As the supporting base material, for example, a resin film such as polyethylene terephthalate can be used.

Further, an organic component such as a binder resin or a solvent is added to the mixed powder of the glass powder 2a and the phosphor powder 2b and kneaded to prepare a slurry. Using the obtained slurry, a green sheet 2'for a phosphor layer is prepared by the same doctor blade method as described above.

Next, in the step (b), the green sheet laminate 20'is obtained by sandwiching the fluorescent material layer green sheet 2'between the plurality of base material layer green sheets 1'. Here, in order to improve the adhesion of each layer, it is preferable to pressurize with a press after laminating the green sheets. In the present embodiment, one green sheet 2'for the phosphor layer is sandwiched between two green sheets 1'for the base material layer to produce the green sheet laminate 20'. Not limited to. For example, in order to adjust the thickness of each layer, the green sheet 1'for the base material layer and the green sheet 2'for the phosphor layer may each be composed of a plurality of green sheets.

Subsequently, in the step (c), by firing the green sheet laminate 20', the glass powder 2a and the phosphor powder 2b are sintered between the two base material layers 1 made of the sintered body of the glass powder 1a. A sintered laminated body 20 in which a phosphor layer 2 made of a body is sandwiched is obtained. In general, green sheets shrink significantly during firing, so when two types of green sheets made of different materials are laminated and fired, warpage and cracks occur due to the difference in the amount of shrinkage due to the difference in the coefficient of thermal expansion of each material. Cheap. On the other hand, in the present embodiment, the stress of the entire member can be balanced by firing with the green sheet 2'for the phosphor layer sandwiched between the two green sheets 1'for the base material layer. Warpage and cracks are less likely to occur during firing.

The firing temperature is preferably within ± 150 ° C., which is the softening point of the glass powder 1a and 2a, and more preferably within ± 100 ° C., which is the softening point of the glass powder 1a and the glass powder 2a. If the firing temperature is too low, the glass powder 1a and the glass powder 2a may not soften and flow, and a dense sintered body may not be obtained. On the other hand, if the firing temperature is too high, the phosphor powder 2b may deteriorate and the emission intensity may decrease.

Finally, in the step (d), one of the base material layers 1 in the sintered laminate 20 is removed to obtain the wavelength conversion member 10. The base material layer 1 can be removed by, for example, polishing or grinding. In the sintered laminate 20 after firing, there is a possibility that stress due to the difference in thermal expansion coefficient between the base material layer 1 and the phosphor layer 2 remains, but the sintered laminate 20 itself Since the mechanical strength is relatively high, even if one of the base material layers 1 is removed by post-processing such as grinding, warpage or cracks are unlikely to occur due to the removal.

In addition, in order to adjust the thickness of the entire wavelength conversion member 10 or to adjust the surface roughness of the wavelength conversion member 10, the base material layer 1 that is not removed may also be polished or ground. .. For example, when the base material layer 1 that is not removed serves as a light emitting surface, the surface roughness of the base material layer 1 is 0.01 to 0.25 μm, 0.03 to 0.24 μm, and 0.05 to 0.23 μm. In particular, it is preferably 0.06 to 0.22 μm. In this way, the light extraction efficiency of the excitation light and the fluorescence can be easily improved.

(Light emitting device)
FIG. 3 is a schematic cross-sectional view showing a light emitting device using the wavelength conversion member according to the embodiment of the present invention.

The light emitting device 100 includes a substrate 3, a light source 4, a wavelength conversion member 10, and a reflection member 5. Specifically, the light source 4 and the wavelength conversion member 10 are sequentially installed on the substrate 3, and the reflection member 5 covers the periphery of the light source 4 and the wavelength conversion member 10. With such a configuration, the excitation light generated by the light source 4 is wavelength-converted by the phosphor layer 2 in the wavelength conversion member 10 to become fluorescence, and passes through the base material layer 1 together with the excitation light not wavelength-converted. It is released to the outside.

The wavelength conversion member 10 is installed so that the phosphor layer 2 side faces the light source 4. Specifically, the wavelength conversion member 10 is installed so that the phosphor layer 2 is in contact with the light source 4. Alternatively, the phosphor layer 2 may be installed so as to be in contact with the light source via an adhesive layer (not shown). A semiconductor element such as an LED or LD is usually used as the light source 4, but since a member having excellent thermal conductivity such as sapphire is used for the light emitting surface of the semiconductor element, the phosphor layer 2 is referred to as the light source 4. When arranged so as to be in contact with each other directly or through the adhesive layer, the heat generated in the phosphor layer 2 can be efficiently discharged to the outside by conducting the constituent members of the light source 4.

As the substrate 3, for example, white LTCC (Low Temperature Co-fired Ceramics) that can efficiently reflect the light rays emitted from the light source 4 is used. Specific examples thereof include a sintered body of glass powder and an inorganic powder such as aluminum oxide, titanium oxide or niobium oxide.

Further, as the substrate 3, a material having high thermal conductivity may be used in order to efficiently release the heat generated from the light source 4. In particular, it is preferable to use a substrate made of ceramics or the like because it is excellent in heat resistance and weather resistance. Specific examples thereof include ceramic substrates such as aluminum oxide and aluminum nitride.

The reflection member 5 is provided to reflect the light leaked from the light source 4 and the wavelength conversion member 10. The reflective member 5 is formed of a resin (highly reflective resin) containing a white pigment such as titanium oxide.

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to these examples.

(Example)
(I) in Preparation mole% of the glass _{powder, SiO 2 61%, Al 2} O 3 4%, B 2 O 3 5%, CaO 16%, BaO 12%, the raw material so that ZnO 2% of the glass composition The mixture was prepared and melted at 1200 to 1700 ° C. for 1 to 2 hours using a platinum crucible to vitrify. The molten glass was formed into a film by flowing it between a pair of cooling rollers. The obtained film-shaped glass molded product was pulverized with a ball mill and then classified to obtain a glass powder having an average particle diameter D ₅₀ of 2.5 μm (softening point 850 ° C., refractive index (nd) 1.58). As the softening point, the fiber elongation method was used, and a temperature at which the viscosity was ^107.6 dPa · s was adopted.

(Ii) Preparation of green sheet for base material layer For glass powder, binder resin (manufactured by Kyoeisha Chemical Co., Ltd., Oricox), plasticizer (manufactured by Kyoeisha Chemical Co., Ltd., DOA), dispersant (manufactured by Kyoeisha Chemical Co., Ltd.) , Floren G-700) and an organic solvent (methyl ethyl ketone) were added and kneaded to obtain a slurry-like mixture. The obtained slurry-like mixture was formed into a sheet by the doctor blade method and dried at room temperature to obtain a green sheet for a base material layer having a thickness of 220 μm.

(Iii) Preparation of green sheet for phosphor layer A binder resin (manufactured by Kyoeisha Chemical Co., Ltd.) is mixed with a glass powder by mixing a phosphor powder (Y ₃ Al ₅ O ₁₂ : Ce, average particle size D ₅₀ = 15 μm). , Oricox), plasticizer (manufactured by Kyoeisha Chemical Co., Ltd., DOA), dispersant (manufactured by Kyoeisha Chemical Co., Ltd., Floren G-700), and organic solvent (methyl ethyl ketone) are added and kneaded to form a slurry mixture. Got The obtained slurry-like mixture was molded into a sheet by the doctor blade method and dried at room temperature to obtain a green sheet for a phosphor layer having a thickness of 120 μm. The amount of the phosphor powder added should be 60% by volume with respect to the total amount of the glass powder and the phosphor powder (in the following characteristic evaluation test, fluorescence obtained by irradiating an excitation light source with white light). Body concentration) was adjusted.

The "white light" in this embodiment is defined as follows. That is, the energy distribution spectrum is integrated from the CIE 1931 2-deg, x (_), y (_), z (_) color matching functions to obtain the tristimulus value XYZ, and the chromaticity x is obtained from this tristimulus value XYZ. When = X / (X + Y + Z) and chromaticity y = Y / (X + Y + Z) are calculated, it is assumed that these values refer to light of a color such that x = 0.33 and y = 0.33, respectively.

(Iv) Preparation of wavelength conversion member After cutting the green sheet for the base material layer and the green sheet for the phosphor layer to a predetermined size, the green sheet for the phosphor layer is sandwiched between the two green sheets for the base material layer. Then, a green sheet laminate was obtained by thermocompression bonding with a press machine. After degreasing the green sheet laminate in an electric furnace, vacuum firing was performed in a vacuum gas replacement furnace near the softening point of the glass powder. As a result, a sintered laminate in which a phosphor layer composed of a sintered body of glass powder and a phosphor powder was sandwiched between two base material layers made of a sintered body of glass powder was obtained.

One of the substrate layers was removed by grinding the sintered laminate. The remaining base material layer and the phosphor layer were finished in a mirror surface state, whereby a wavelength conversion member including a base material layer having a thickness of 90 μm and a phosphor layer having a thickness of 30 μm formed on one of the main surfaces was obtained.

(V) Characteristic evaluation test For the obtained wavelength conversion member, the changes over time in total luminous flux value and chromaticity were measured as follows.

A light emitting device was obtained by adhering a wavelength conversion member on an LED light source having an excitation wavelength of 450 nm with a silicone resin adhesive and covering the outer periphery of the LED light source and the wavelength conversion member with a reflection member. Here, the wavelength conversion member is arranged so that the phosphor layer side faces the light source. A direct current of 1.0 A was applied to this light emitting device to turn on the light source. After taking the light emitted from the wavelength conversion member into the integrating sphere, the light was guided to a spectroscope calibrated by a standard light source, and the energy distribution spectrum of the light was measured. The total luminous flux value was calculated by multiplying the obtained spectrum by the standard luminosity function. When the total luminous flux value was continuously measured from the lighting of the light source to 180 seconds later, the rate of change of the total luminous flux value was 0.96 when 1 was set immediately after lighting.

Further, when the chromaticity x calculated from the above-mentioned formula was continuously measured from the lighting of the light source to the lapse of 180 seconds, the amount of change (decrease) was 0.002.

(Comparison example)
A green sheet for a phosphor layer having a thickness of 320 μm was obtained by the same method as in Example 1. The amount of the phosphor powder added should be 8.5% by volume based on the total amount of the glass powder and the phosphor powder (in the characteristic evaluation test, white light is obtained when the excitation light source is irradiated). Body concentration) was adjusted.

The green sheet for the phosphor layer cut to a predetermined size was degreased in an electric furnace, and then vacuum fired in a vacuum gas replacement furnace near the softening point of the glass powder. The sintered body of the glass powder and the phosphor powder thus obtained was ground into a mirror surface state to obtain a wavelength conversion member having a thickness of 120 μm.

The obtained wavelength conversion member was subjected to the same characteristic evaluation test as in the examples. As a result, the rate of change of the total luminous flux value was 0.91 when the value immediately after lighting was 1, and the amount of change (decrease) in the chromaticity x was 0.012.

From the above, it can be seen that the wavelength conversion member of the present invention has little decrease in luminous flux value and change in chromaticity with time after lighting, and it is easy to obtain a desired luminous flux value and chromaticity.

1 Base material layer 1a Glass powder 1'Green sheet for base material layer 2 Fluorescent material layer 2a Glass powder 2b Fluorescent material powder 2'Green sheet for phosphor layer 3 Substrate 4 Light source 5 Reflective member 10 Wavelength conversion member 20 Sintered laminate 20'Green Sheet Laminated Body 100 Light Source

Claims (14)

A base material layer made of a sintered glass powder and
A phosphor layer formed on one main surface of the base material layer and composed of a sintered body of glass powder and phosphor powder,
A wavelength conversion member comprising. The wavelength conversion member according to claim 1, wherein the thickness of the base material layer is larger than the thickness of the phosphor layer. The wavelength conversion member according to claim 2, wherein the thickness of the base material layer is 1.1 to 10 times the thickness of the phosphor layer. The wavelength conversion member according to any one of claims 1 to 3, wherein the base material layer has a thickness of 45 to 900 μm. The wavelength conversion member according to any one of claims 1 to 4, wherein the thickness of the phosphor layer is 5 to 100 μm. The wavelength conversion member according to any one of claims 1 to 5, wherein the content of the fluorescent substance powder in the fluorescent substance layer is 1 to 80% by volume. The wavelength conversion member according to any one of claims 1 to 6, wherein the fluorescent substance powder is a garnet-based phosphor. The wavelength conversion member according to any one of claims 1 to 7, wherein the average particle size of the phosphor powder is 1 to 50 μm. The wavelength conversion member according to any one of claims 1 to 8, wherein the glass powder in the base material layer and the glass powder in the phosphor layer have substantially the same composition. The wavelength conversion member according to any one of claims 1 to 9, wherein the base material layer and / or the phosphor layer contains a filler powder. A method for producing the wavelength conversion member according to any one of claims 1 to 10.
(A) A step of preparing a green sheet for a base material layer containing glass powder and a green sheet for a phosphor layer containing glass powder and a phosphor powder.
(B) A step of obtaining a green sheet laminate by sandwiching the fluorescent material layer green sheet between a plurality of the base material layer green sheets.
(C) By firing the green sheet laminate, the phosphor layer made of the sintered body of the glass powder and the phosphor powder is sandwiched between the two base material layers made of the sintered body of the glass powder. The process of obtaining a sintered laminate made of powder, and
(D) A step of removing one of the base material layers in the sintered laminate,
A method for manufacturing a wavelength conversion member, which comprises. A light emitting device comprising the wavelength conversion member according to any one of claims 1 to 10 and a light source for irradiating the wavelength conversion member with excitation light of the phosphor powder. The light emitting device according to claim 12, wherein the wavelength conversion member is arranged so that the phosphor layer faces the light source. The light emitting device according to claim 13, wherein the phosphor layer is in contact with a light source directly or via an adhesive layer.