Wavelength conversion member, wavelength conversion device, and light source device

Abstract

To provide a technique of increasing the joint strength of a wavelength conversion member.SOLUTION: The wavelength conversion member includes: a ceramic phosphor for converting the wavelength of incident light; a reflection film arranged on the ceramic phosphor, the reflection film including a first metal reflecting light and a high melting point particle made of a material of which melting point is higher than that of the first metal; and a joint auxiliary layer arranged between a joint layer arranged between a member arranged on the opposite side of the reflection film to the side where the ceramic phosphor is arranged and the reflection film, and the reflection film, the joint auxiliary layer having a sintered tissue based on a second metal.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wavelength conversion member, a wavelength conversion device, and a light source device.

Background Art

[0002] Conventionally, wavelength conversion members that convert the wavelength of light emitted from a light source are known. A wavelength conversion member generally includes a phosphor that converts the wavelength of incident light, and a reflective film that reflects the light incident on the phosphor toward the incident direction, and the reflective film directs the light in a predetermined direction to reflect the light, thereby improving the emission intensity of the wavelength conversion member. For example, Patent Document 1 discloses a technique for forming a reflective film by sintering a mixture of silver particles and glass. Further, Patent Document 2 discloses a wavelength conversion member in which high-melting-point particles having a melting point higher than that of silver are dispersed in a reflective film formed of silver.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, even with prior art such as Patent Documents 1 and 2, there was still room for improvement in techniques for improving the bonding strength between wavelength conversion members and other members via a reflective film. For example, in the technique of Patent Document 1, when forming the reflective film, the glass that flows due to softening is distributed on the surface of the phosphor, and there is a risk that the softened glass and the phosphor will react. When the glass and phosphor react, variations occur in the bonding strength between the reflective film and the phosphor, which may reduce the bonding strength between the phosphor and the heat dissipation member via the reflective film. Also, in the technique of Patent Document 2, when forming the reflective film, high-melting-point particles tend to appear on the surface of the reflective film. If high-melting-point particles are present on the surface of the reflective film, the wettability of the bonding layer that bonds the reflective film and the heat dissipation member to the reflective film decreases, which may reduce the bonding strength.

[0005] The present invention aims to provide a technique for improving bonding strength in wavelength conversion members. [Means for solving the problem]

[0006] The present invention has been made to solve at least some of the above-mentioned problems and can be realized in the following forms.

[0007] (1) According to one embodiment of the present invention, a wavelength conversion member is provided. This wavelength conversion member comprises a ceramic phosphor that converts the wavelength of incident light; a reflective film disposed on the ceramic phosphor and containing a first metal that reflects light and high-melting-point particles made of a material with a higher melting point than the first metal; a bonding layer disposed between the member disposed on the opposite side of the reflective film from the ceramic phosphor and the reflective film and the reflective film; and a bonding auxiliary layer disposed between the reflective film and the bonding auxiliary layer having a sintered structure mainly composed of a second metal.

[0008] In this configuration, the reflective film placed on the ceramic phosphor contains high-melting-point particles with a higher melting point than the first metal of the reflective film. This improves the bonding strength between the ceramic phosphor and the reflective film, but the high-melting-point particles, which reduce the wettability of the bonding layer, tend to appear on the surface of the reflective film. The bonding auxiliary layer is placed between the bonding layer and the reflective film, so the reflective film, where high-melting-point particles tend to appear on the surface, is not directly bonded to the bonding layer. Furthermore, the bonding auxiliary layer has a sintered structure mainly composed of a second metal. Here, "sintered structure mainly composed of a second metal" refers to a sintered structure in which 80% or more by volume is composed of the second metal. As a result, the bonding auxiliary layer can bond well to the reflective film where high-melting-point particles appear on the surface. Therefore, the bonding strength between the wavelength conversion member and other members via the bonding layer can be improved.

[0009] (2) In the wavelength conversion member of the above form, the bonding auxiliary layer may include glass. With this configuration, by including glass in the bonding auxiliary layer which has a high affinity for high melting point particles, it is possible to bond even better with the reflective film on which high melting point particles are present on the surface. Therefore, the bonding strength between the wavelength conversion member and other members via the bonding layer can be further improved.

[0010] (3) According to another embodiment of the present invention, a wavelength conversion device is provided. This wavelength conversion device comprises the above-described wavelength conversion member, a heat dissipation member as the member for releasing heat from the ceramic phosphor to the outside, and a bonding layer for bonding the heat dissipation member and the bonding auxiliary layer, wherein the bonding layer is formed to cover the respective sides of the reflective film and the bonding auxiliary layer. With this configuration, the reflective film, in which high-melting-point particles that reduce the wettability of the bonding layer tend to appear on the surface, is bonded to the bonding layer via a bonding auxiliary layer that can also bond well to the bonding layer. As a result, since the bonding layer is formed to cover the respective sides of the bonding auxiliary layer and the reflective film, the bonding strength between the wavelength conversion member and the heat dissipation member can be improved.

[0011] (4) According to yet another embodiment of the present invention, a light source device is provided. This light source device comprises the wavelength conversion member described above and a light source that irradiates the ceramic phosphor with light. With this configuration, the light source device emits light using a wavelength conversion member in which the bonding strength between the wavelength conversion member and other members via a bonding layer is improved. As a result, the bonded state between the wavelength conversion member and other members is maintained for a long period of time, and the lifespan of the light source device can be extended.

[0012] (5) According to yet another embodiment of the present invention, a light source device is provided. This light source device comprises the wavelength conversion device described above and a light source for irradiating the ceramic phosphor with light. With this configuration, light can be emitted using a wavelength conversion device in which the bonding strength between the heat dissipation member and the wavelength conversion member via the bonding layer is improved. As a result, the bonded state between the wavelength conversion member and the heat dissipation member is maintained for a long period of time due to the improved bonding strength, thereby suppressing temperature quenching of the ceramic phosphor and extending the life of the light source device.

[0013] Furthermore, the present invention can be realized in various forms, for example, as an apparatus including a wavelength conversion member, a system including a light source device, a method for manufacturing the wavelength conversion member and the light source device, a method for manufacturing a reflective film, and so on. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic cross-sectional view of the wavelength conversion member of the first embodiment. [Figure 2] This is a schematic diagram of the light source device of the first embodiment. [Figure 3] This is an enlarged view of a portion of a schematic cross-sectional diagram of the wavelength conversion unit. [Figure 4] This diagram illustrates the results of evaluation tests on wavelength conversion components. [Modes for carrying out the invention]

[0015] <First Embodiment> Figure 1 is a schematic cross-sectional view of the wavelength conversion member 1 of the first embodiment. The wavelength conversion member 1 of this embodiment comprises a ceramic phosphor 10, a reflective film 20, and a bonding auxiliary layer 30. When light is incident on the wavelength conversion member 1, it emits light of a different wavelength than the incident light. The wavelength conversion member 1 of this embodiment is used in various optical devices such as projectors, headlamps, lighting, and head-up displays. In Figure 1, the stacking direction, which is the direction in which the ceramic phosphor 10, the reflective film 20, and the bonding auxiliary layer 30 are stacked, is indicated by the dashed arrow DL. Note that the relationship between the size and thickness of the ceramic phosphor 10, the reflective film 20, and the bonding auxiliary layer 30 in Figure 1 is illustrated differently from the actual size and thickness relationship for the sake of explanation.

[0016] The ceramic phosphor 10 is a ceramic sintered body, and in this embodiment, it is formed in a substantially cylindrical shape. The ceramic phosphor 10 has an incident surface 11 to which light is incident, and a back surface 12 located on the opposite side of the incident surface 11. The ceramic phosphor 10 converts at least a portion of the wavelength of the light incident from the incident surface 11 and emits light of a different wavelength from the incident light. The ceramic phosphor 10 is composed of a ceramic sintered body having a fluorescent phase mainly composed of fluorescent crystalline particles and a translucent phase mainly composed of translucent crystalline particles. The crystalline particles of the translucent phase have a composition represented by the chemical formula Al2O3, and the crystalline particles of the fluorescent phase have a composition represented by the chemical formula A3B5O 12 It is preferable to have a composition represented by :Ce (a so-called garnet structure). "A3B5O 12 :Ce" is A3B5O 12 This indicates that Ce is in solid solution within the mixture, and that some of element A is substituted by Ce.

[0017] Chemical formula A3B5O 12 Element A and element B in Ce are each composed of at least one element selected from the following group of elements. Element A: Lanthanides excluding Sc, Y, and Ce (however, element A may also include Gd). Element B: Al (however, element B may also include Ga) By using a ceramic sintered body as the ceramic phosphor 10, light is scattered at the interface between the fluorescent phase and the light-transmitting phase, whereby the angular dependence of light color can be reduced. This makes it possible to improve color homogeneity. Note that the material of the ceramic phosphor 10 is not limited to the materials described above.

[0018] The reflective film 20 is disposed on the back surface 12 of the ceramic phosphor 10. The reflective film 20 includes silver (Ag) 21 that reflects light, and high-melting-point particles 22 made of a material having a melting point higher than that of silver. The material forming the high-melting-point particles 22 is, for example, alumina (Al₂O₃). The particle size of the high-melting-point particles 22 contained in the reflective film 20 is preferably 1 μm to 50 μm. The volume fraction of the high-melting-point particles 22 in the reflective film 20 is preferably 3% to 30%. In the present embodiment, the reflective film 20 has a thickness of 30 μm to 100 μm. In the reflective film 20, light that has passed through the ceramic phosphor 10 and light generated by the ceramic phosphor 10 are reflected by the silver 21. As a result, in a device including the wavelength conversion member 1, the emission intensity can be improved. Note that the relationship between the metal material contained in the reflective film 20 and the material forming the high-melting-point particles is not limited to this. The metal contained in the reflective film 20 is not limited to silver, and may be aluminum (Al), platinum (Pt), palladium (Pd), or the like. The material forming the high-melting-point material may be any material having a melting point higher than that of the metal contained in the reflective film 20, and for example, an oxide with relatively low reactivity is preferable. Further, the material forming the high-melting-point particles 22 is not limited to alumina, and may be ceramics such as YAG, TiO₂, Y₂O₃, SiO₂, Cr₂O₃, Nb₂O₅, Ta₂O₂, AlN, Si₃N₄, or metals such as nickel (Ni), tungsten (W), molybdenum (Mo), chromium (Cr), niobium (Nb).

[0019] The bonding auxiliary layer 30 is disposed on the side opposite to the ceramic phosphor 10 with respect to the reflective film 20. The bonding auxiliary layer 30 has a sintered structure containing silver 31 as a main component. The term "sintered structure containing silver 31 as a main component" refers to a sintered structure in which 80% or more by volume fraction is composed of silver 31. For this reason, the bonding auxiliary layer 30 is formed in a porous state and has a plurality of voids inside. Whether or not the bonding auxiliary layer 30 has a sintered structure is determined by observing an SEM image captured by a scanning electron microscope (SEM). Specifically, in the SEM image, when it is observed that the voids are regularly distributed and that a portion of each of the plurality of silver particles remains without being melted, the bonding auxiliary layer 30 is determined to have a sintered structure. In the bonding auxiliary layer 30 of the present embodiment, the porosity, which is the ratio of the area occupied by voids to the total area of the SEM image, is 50% or more. In the present embodiment, the bonding auxiliary layer 30 has a thickness of 30 μm to 100 μm. The metal material forming the sintered structure of the bonding auxiliary layer 30 is not limited to silver. It may be a metal different from the metal contained in the reflective film 20.

[0020] In the present embodiment, the bonding auxiliary layer 30 contains glass 32. The glass 32 of the present embodiment is an oxide containing silicon (Si) or bismuth (Bi), and is contained in the bonding auxiliary layer 30 at a volume fraction of about several percent. In the present embodiment, the volume fraction of the glass 32 contained in the bonding auxiliary layer 30 refers to the ratio of the area of the glass 32 to the sum of the area of the silver 31 and the area of the glass 32 in the aforementioned SEM image. It is preferable that the glass 32 does not form a continuous layer at either the interface between the reflective film 20 and the bonding auxiliary layer 30 or the interface between a bonding layer 50 (described later) and the bonding auxiliary layer 30. The glass 32 contained in the bonding auxiliary layer 30 has high affinity with the high-melting-point particles 22 made of alumina contained in the reflective film 20. Thereby, the bonding strength between the reflective film 20 and the bonding auxiliary layer 30 can be improved.

[0021] Figure 2 is a schematic diagram of the light source device 2 of the first embodiment. The light source device 2 of this embodiment comprises a wavelength conversion device 3 and a light source 4 that emits light. The wavelength conversion device 3 comprises a wavelength conversion member 1, a heat dissipation member 40 that releases heat from the ceramic phosphor 10 to the outside, and a bonding layer 50 that bonds the wavelength conversion member 1 and the heat dissipation member 40. In the wavelength conversion device 3, as shown in Figure 2, the ceramic phosphor 10, reflective film 20, bonding auxiliary layer 30, bonding layer 50, and heat dissipation member 40 are stacked in that order. Figure 2 shows a dashed arrow DL indicating the stacking direction of the ceramic phosphor 10, reflective film 20, bonding auxiliary layer 30, bonding layer 50, and heat dissipation member 40.

[0022] In the light source device 2, light L1 emitted from a light source 4, such as a light-emitting diode (LED) or a semiconductor laser (LD), is irradiated onto the ceramic phosphor 10 of the wavelength conversion device 3. The ceramic phosphor 10, irradiated with light L1, emits light of a different wavelength than light L1. As a result, the wavelength conversion device 3 emits light L2 of a different color than the light L1 emitted from the light source 4. Such a wavelength conversion device 3 is used in various optical devices such as projectors, headlamps, lighting, and head-up displays. Note that the relationship between the size and thickness of the ceramic phosphor 10, reflective film 20, bonding auxiliary layer 30, heat dissipation member 40, and bonding layer 50 in Figure 2 is illustrated differently from the actual size or thickness relationship for the sake of explanation.

[0023] The heat dissipation member 40 is a flat plate-shaped member formed from a material having higher thermal conductivity than the ceramic phosphor 10, such as copper (Cu), copper-molybdenum alloy, copper-tungsten alloy, Al, or AlN. The heat dissipation member 40 releases the heat from the ceramic phosphor 10 transmitted through the bonding layer 50 to the outside of the wavelength conversion device 3. The heat dissipation member 40 does not have to be a single-layer member made of the above-mentioned material, but may be a multilayer member made of the same or different materials. In addition, a plating may be placed on the surface of the heat dissipation member 40 facing the ceramic phosphor 10 to improve adhesion with the bonding layer 50.

[0024] The bonding layer 50 is positioned between the wavelength conversion member 1 and the heat dissipation member 40. That is, the bonding auxiliary layer 30 is positioned between the bonding layer 50, which is positioned between the reflective film 20 and the member (heat dissipation member 40) positioned on the opposite side of the ceramic phosphor 10 from the reflective film 20, and the reflective film 20. The bonding layer 50 is formed of gold and tin, and bonds the ceramic phosphor 10 and the heat dissipation member 40 via the reflective film 20 and the bonding auxiliary layer 30. In this embodiment, the bonding layer 50 is formed to cover the respective side surfaces 20a, 30a of the reflective film 20 and the bonding auxiliary layer 30.

[0025] Next, the manufacturing method of the light source device 2 will be described. First, the raw materials are weighed so that the ratio of the fluorescent phase to the translucent phase is, for example, 6:4. The weighed raw materials are put into a ball mill with ethanol or pure water and pulverized and mixed for 16 hours to produce a slurry for the ceramic phosphor. The slurry for the ceramic phosphor is dried and granulated, then a binder and water are added, and the mixture is kneaded while applying shear force to produce a clay body. The prepared clay body is formed into a sheet using an extrusion molding machine, and the formed sheet is fired in an atmospheric environment at approximately 1700°C. The fired body obtained by firing is cut to a predetermined thickness to produce the ceramic phosphor 10.

[0026] After preparing the ceramic phosphor 10, a paste for the reflective film is prepared by mixing silver powder, alumina powder, an acrylic binder, and a solvent. The prepared reflective film paste is applied to the back surface 12 of the ceramic phosphor 10 and dried, and then the ceramic phosphor 10 with the reflective film paste applied is heated. By heating the ceramic phosphor 10 with the reflective film paste applied, the reflective film paste is baked onto the back surface 12 of the ceramic phosphor 10, and a reflective film 20 is formed on the ceramic phosphor 10.

[0027] After forming a reflective film 20 on the ceramic phosphor 10, a paste for the bonding auxiliary layer is prepared by mixing silver powder, glass powder, a binder, and a solvent. The prepared bonding auxiliary layer paste is applied to the side of the reflective film 20 opposite to the ceramic phosphor 10, dried, and then heated. This completes the wavelength conversion member 1.

[0028] After the wavelength conversion member 1 is completed, an AuSn solder foil is sandwiched between the bonding auxiliary layer 30 of the wavelength conversion member 1 and the heat dissipation member 40, and the AuSn solder foil is melted by heating it in a reflow oven, for example. This bonds the wavelength conversion member 1 and the heat dissipation member 40, completing the wavelength conversion device 3. Finally, the light source 4 is positioned so that light L1 is irradiated onto the incident surface 11 of the wavelength conversion device 3. This completes the light source device 2.

[0029] Next, the features of the reflective film 20 and bonding auxiliary layer 30 provided in the wavelength conversion member 1 of this embodiment will be described. In this embodiment, the reflective film 20 includes silver 21 that reflects light and high-melting-point particles 22 made of alumina, which has a higher melting point than silver 21. The bonding auxiliary layer 30 is disposed between the bonding layer 50, which is disposed between the heat dissipation member 40, which is located on the opposite side of the reflective film 20 from the ceramic phosphor 10, and the reflective film 20, and has a sintered structure mainly composed of silver.

[0030] Figure 3 is an enlarged view of a portion of the schematic cross-sectional diagram of the wavelength conversion device 3. Figure 3 shows a portion of the cross-section along the stacking direction DL in the wavelength conversion device 3. As shown in Figure 3, multiple high-melting-point particles 22 are present in the reflective film 20. This is because a mixture of silver powder and alumina powder is used as the paste for the reflective film when forming the reflective film 20 on the ceramic phosphor 10. By using a mixture of silver powder and alumina powder as the paste for the reflective film, the wettability with the ceramic phosphor 10 is increased, thereby improving the bonding strength between the ceramic phosphor 10 and the reflective film 20. Since the high-melting-point particles 22 have a higher melting point than silver 21, they do not melt even when the ceramic phosphor 10 coated with the reflective film paste is heated. As a result, the reaction between the high-melting-point particles 22 and the ceramic phosphor 10 is suppressed, thereby suppressing a decrease in reflectivity, and the high-melting-point particles 22 are appropriately dispersed within the reflective film 20, thereby suppressing variations in the bonding strength between the ceramic phosphor 10 and the reflective film 20.

[0031] The bonding auxiliary layer 30 has a sintered structure mainly composed of silver 31. This allows the bonding auxiliary layer 30 to bond well with the reflective film 20 on which high-melting-point particles 22 are present on the surface. As shown in Figure 3, the bonding auxiliary layer 30 contains multiple glass particles 32. The glass particles 32 in the bonding auxiliary layer 30 are formed when glass powder contained in the bonding auxiliary layer paste melts and solidifies during the manufacturing of the wavelength conversion member 1. During the manufacturing of the wavelength conversion member 1, the molten glass moves between the silver powder particles contained in the bonding auxiliary layer paste and readily bonds with the high-melting-point particles 22 present on the surface 20b of the reflective film 20. This improves the bonding strength between the reflective film 20 and the bonding auxiliary layer 30.

[0032] Next, we will describe the evaluation test of the wavelength conversion component. In this evaluation test, we assessed the effect of the presence or absence of a bonding auxiliary layer on the surface temperature of the ceramic phosphor in the wavelength conversion component.

[0033] The sample used in this evaluation test was a light source device, manufactured using the manufacturing method of the light source device 2 of this embodiment described above. In this evaluation test, the reflective film and the bonding auxiliary layer were manufactured under the following conditions. • Reflective film (thickness: 30 μm) Metal type: silver High melting point particle material: Alumina Particle size of alumina particles added during manufacturing: 10 μm Amount of alumina particles added during manufacturing (by volume): 15% • Bonding auxiliary layer (thickness 30 μm) Metal type: silver Components added to the glass during manufacturing: Oxides containing Si and Bi. Amount of glass added during manufacturing (by volume): 1% In this evaluation test, two types of samples were prepared: Sample 1, which did not have a bonding auxiliary layer, and Sample 2, which did have a bonding auxiliary layer. Since voids were observed in the bonding auxiliary layer of Sample 2 using a scanning electron microscope, it was confirmed that the bonding auxiliary layer of Sample 2 had a silver sintered structure. The porosity of the bonding auxiliary layer of Sample 2 was 2%.

[0034] In this evaluation test, the surface temperature of the ceramic phosphor was measured using a radiation thermometer after irradiating the prepared sample with laser light for a certain period of time, and the temperature before the test was obtained. After obtaining the temperature before the test, a thermal shock test was performed on the sample by repeating heating and cooling a certain number of times. After the thermal shock test, the surface temperature of the ceramic phosphor was measured again using a radiation thermometer after irradiating it with laser light for a certain period of time, and the temperature after the test was obtained. Finally, the ratio of the temperature after the test to the temperature before the test was calculated. The specific information regarding the test conditions for the thermal shock test and the surface temperature measurement conditions in this evaluation test is as follows. • Test conditions for thermal shock testing Maximum temperature: 200℃ Minimum temperature: 0℃ Holding time: 30 minutes Number of repetitions: 500 times • Surface temperature measurement conditions Laser wavelength: 450nm; Laser beam diameter: 1mm Laser output: 70W, irradiation time: 1 minute

[0035] Figure 4 illustrates the results of the evaluation test of the wavelength conversion component. Figure 4 shows the ratio of the temperature after the test to the temperature before the test, multiplied by 100 ("Rtmax (%)" in Figure 4) for each of the two types of samples, 1 and 2. As shown in Figure 4, sample 1, which does not have a bonding auxiliary layer, has an Rtmax of 180%, while sample 2, which has a bonding auxiliary layer, has an Rtmax of 100%. The result for sample 1, which does not have a bonding auxiliary layer, indicates that the bonding strength between the reflective film and the bonding layer is relatively small, causing delamination to progress at the interface between the reflective film and the bonding layer, resulting in reduced heat dissipation. On the other hand, the result for sample 2, which has a bonding auxiliary layer, indicates that the bonding strength between the reflective film and the bonding layer via the bonding auxiliary layer is large, so heat dissipation by the heat dissipation component is sufficient without delamination.

[0036] As described above, according to the wavelength conversion member 1 of this embodiment, the reflective film 20 disposed on the ceramic phosphor 10 contains high-melting-point particles 22, which have a higher melting point than silver 21. Therefore, while the bonding strength between the ceramic phosphor 10 and the reflective film 20 is improved, the high-melting-point particles 22, which reduce the wettability of the bonding layer 50, tend to appear on the surface of the reflective film 20. Since the bonding auxiliary layer 30 is disposed between the bonding layer 50 and the reflective film 20, the reflective film 20, where the high-melting-point particles 22 tend to appear on the surface, and the bonding layer 50 are not directly bonded. Furthermore, the bonding auxiliary layer 30 has a sintered structure mainly composed of silver 31, and can bond well with the reflective film 20, where the high-melting-point particles 22 appear on the surface. Therefore, the bonding strength between the wavelength conversion member 1 and other members such as the heat dissipation member 40 via the bonding auxiliary layer 30 and the bonding layer 50 can be improved.

[0037] Furthermore, according to the wavelength conversion member 1 of this embodiment, the bonding auxiliary layer 30 has a sintered structure mainly composed of silver 31, and is formed by heating at a temperature below the melting point of silver 31. That is, since the temperature for forming the bonding auxiliary layer 30 is below the melting point of silver, when manufacturing the wavelength conversion member 1, it is possible to suppress the remelting of the already formed silver-containing reflective film 20 when forming the bonding auxiliary layer 30. Therefore, it is possible to suppress the decrease in reflectivity of the reflective film 20 due to remelting.

[0038] Furthermore, in the wavelength conversion device 3 of this embodiment, the bonding auxiliary layer 30 is positioned between the ceramic phosphor 10 and the heat dissipation member 40. This makes it possible to alleviate stress caused by the difference in thermal expansion between the ceramic phosphor 10 and the heat dissipation member 40. Therefore, damage to the wavelength conversion device 3 can be suppressed.

[0039] Furthermore, according to the wavelength conversion member 1 of this embodiment, the bonding auxiliary layer 30 contains glass 32 which has a high affinity for high melting point particles 22, allowing for even better bonding with the reflective film 20 on which high melting point particles 22 are present on the surface. Therefore, the bonding strength between the wavelength conversion member 1 and the heat dissipation member 40 via the bonding auxiliary layer 30 and the bonding layer 50 can be further improved.

[0040] Furthermore, according to the wavelength conversion member 1 of this embodiment, the glass contained in the bonding auxiliary layer 30 melts during the manufacturing of the wavelength conversion member 1 and readily bonds with the high-melting-point particles 22 contained in the reflective film 20. As a result, on the side of the bonding auxiliary layer 30 opposite to the reflective film 20, i.e., the side that bonds with the bonding layer 50, there is no glass that would reduce the wettability of the bonding layer 50, thus enabling good bonding with the bonding layer 50.

[0041] Furthermore, according to the wavelength conversion device 3 of this embodiment, the reflective film 20, in which high-melting-point particles 22 that reduce the wettability of the bonding layer 50 tend to appear on the surface, is bonded to the bonding layer 50 via a bonding auxiliary layer 30 that can also bond well to the bonding layer 50. As a result, the bonding layer 50 is formed to cover the respective side surfaces 20a, 30a of the bonding auxiliary layer 30 and the reflective film 20, thereby improving the bonding strength between the wavelength conversion member 1 and the heat dissipation member 40.

[0042] Furthermore, according to the light source device 2 of this embodiment, light is emitted using a wavelength conversion member 1 in which the bonding strength between the heat dissipation member 40 and the wavelength conversion member 1 via the bonding layer 50 is improved. As a result, the state in which the wavelength conversion member 1 and the heat dissipation member 40 are bonded is maintained for a long period of time, thereby suppressing temperature quenching of the ceramic phosphor 10 and extending the lifespan of the light source device 2.

[0043] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0044] [Example 1] In the above embodiment, the "first metal" contained in the reflective film is silver, and the "second metal" contained in the bonding auxiliary layer is also silver. However, the "first metal" and the "second metal" do not have to be the same type of metal; they may be different. When manufacturing the wavelength conversion member, it is desirable that the melting point of the first metal be equal to or greater than the melting point of the second metal so that the reflective film does not remelt when forming the bonding auxiliary layer. However, when forming the bonding auxiliary layer, the second metal forms a sintered structure at a temperature lower than its melting point, so this is not a limitation.

[0045] [Differentiation 2] In the above embodiment, the bonding auxiliary layer included glass. However, the bonding auxiliary layer does not need to contain glass. Even without glass, a bonding auxiliary layer having a silver sintered structure can bond well with the bonding layer while improving the bonding strength with the reflective film.

[0046] [Difference 3] In the above-described embodiment, the wavelength conversion device 3 comprises a wavelength conversion member 1, a bonding layer 50, and a heat dissipation member 40, and the wavelength conversion member 1 comprises a ceramic phosphor 10, a reflective film 20, and a bonding auxiliary layer 30. However, the configuration of the wavelength conversion member 1 and the wavelength conversion device 3 is not limited to these. They may also include a sealing film, a plating layer, and the like.

[0047] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate.

[0048] [Application Example 1] A wavelength conversion member, A ceramic phosphor that converts the wavelength of incident light, A reflective film comprising a first metal that reflects light and a high-melting-point particle made of a material with a higher melting point than the first metal, disposed on the ceramic phosphor, The system comprises a bonding layer disposed between the reflective film and a member disposed on the opposite side of the reflective film from the ceramic phosphor, and a bonding auxiliary layer disposed between the reflective film and the bonding auxiliary layer having a sintered structure mainly composed of a second metal. A wavelength conversion member characterized by the following features. [Application Example 2] The wavelength conversion member described in Application Example 1, The bonding auxiliary layer includes glass, A wavelength conversion member characterized by the following features. [Application Example 3] A wavelength conversion device, A wavelength conversion member as described in Application Example 1 or Application Example 2, A heat dissipation member, which is the component that releases the heat of the ceramic phosphor to the outside, The heat dissipation member and the bonding auxiliary layer are joined together by the bonding layer, The bonding layer is formed to cover the respective sides of the reflective film and the bonding auxiliary layer. A wavelength conversion device characterized by the following features. [Application Example 4] A light source device, A wavelength conversion member as described in Application Example 1 or Application Example 2, The system comprises a light source for irradiating the ceramic phosphor with light, A light source device characterized by the following features. [Application Example 5] A light source device, The wavelength conversion device described in Application Example 3, The system comprises a light source for irradiating the ceramic phosphor with light, A light source device characterized by the following features. [Explanation of Symbols]

[0049] 1...Wavelength conversion component 2...Light source device 3…Wavelength conversion device 4...Light source 10…Ceramic phosphor 20…Reflection film 20a... (Side of the reflective film) 21... Silver 22... High melting point particles 30...bonding auxiliary layer 30a... (Side of the bonding auxiliary layer) 31... Silver 32…Glass 40…Heat dissipation components 50...Joining layer

Claims

1. A wavelength conversion member, A ceramic phosphor that converts the wavelength of incident light, A reflective film comprising a first metal that reflects light and a high-melting-point particle made of a material with a higher melting point than the first metal, disposed on the ceramic phosphor, The system comprises a bonding layer disposed between the reflective film and a member disposed on the opposite side of the reflective film from the ceramic phosphor, and a bonding auxiliary layer disposed between the reflective film and the bonding auxiliary layer having a sintered structure mainly composed of a second metal, The bonding auxiliary layer contains glass made of silicon (Si) or an oxide containing bismuth (Bi), The aforementioned high-melting-point particles consist of one of the following materials: alumina (Al₂O₃), YAG, TiO₂, Y₂O₃, SiO₂, Cr₂O₃, Nb₂O₅, Ta₂O₂, AlN, Si₃N₄, nickel (Ni), tungsten (W), molybdenum (Mo), chromium (Cr), or niobium (Nb). A wavelength conversion member characterized by the following features.

2. A wavelength conversion device, The wavelength conversion member according to claim 1, A heat dissipation member, which is the component that releases the heat of the ceramic phosphor to the outside, The heat dissipation member and the bonding auxiliary layer are joined together by the bonding layer, The bonding layer is formed to cover the respective sides of the reflective film and the bonding auxiliary layer. A wavelength conversion device characterized by the following features.

3. A light source device, A wavelength conversion member according to claim 1 or claim 2, The system comprises a light source for irradiating the ceramic phosphor with light, A light source device characterized by the following features.

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