JP2024099928A - Wavelength conversion member, wavelength conversion device, and light source device - Google Patents

Abstract

[Problem] To provide a technology for improving the bonding strength in a wavelength conversion member. [Solution] The wavelength conversion member includes 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 melting point higher than that of the first metal, 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, the bonding auxiliary layer having a sintered structure mainly composed of a second metal. [Selected Figure] Figure 1

Description

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

Conventionally, wavelength conversion members that convert the wavelength of light emitted by a light source have been known. Wavelength conversion members generally include a phosphor that converts the wavelength of incident light, and a reflective film that reflects the light incident on the phosphor in the direction of incidence, and the luminous intensity of the wavelength conversion member is improved by reflecting the light in a predetermined direction with the reflective film. For example, Patent Document 1 discloses a technology for forming a reflective film by sintering a mixture of silver particles and glass. Patent Document 2 discloses a wavelength conversion member in which high-melting-point particles with a melting point higher than that of silver are dispersed in a reflective film formed from silver.

Special Publication No. 2016-534396 International Publication No. 2022/163175

However, even with the prior art such as Patent Documents 1 and 2, there is still room for improvement in the technology for improving the bonding strength between the wavelength conversion member and other members via the reflective film. For example, in the technology of Patent Document 1, when the reflective film is formed, the glass that flows due to softening is distributed on the surface of the phosphor, and there is a risk of the softened glass reacting with the phosphor. If the glass reacts with the phosphor, the bonding strength between the reflective film and the phosphor varies, and for example, the bonding strength between the phosphor and the heat dissipation member via the reflective film may decrease. In addition, in the technology of Patent Document 2, when the reflective film is formed, high-melting-point particles are likely 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, and there is a risk of the bonding strength decreasing.

The present invention aims to provide a technology that improves the bonding strength in wavelength conversion members.

The present invention has been made to solve at least some of the above problems, and can be realized in the following form.

(1) According to one aspect of the present invention, a wavelength conversion member is provided. The wavelength conversion member includes a ceramic phosphor that converts the wavelength of incident light, a reflective film disposed on the ceramic phosphor and including a first metal that reflects light and high-melting-point particles made of a material having a melting point higher than that of the first metal, 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 ceramic phosphor, the bonding auxiliary layer having a sintered structure mainly composed of a second metal.

According to this configuration, the reflective film disposed on the ceramic phosphor contains high-melting-point particles having a higher melting point than the first metal of the reflective film, so that the bonding strength between the ceramic phosphor and the reflective film is improved, while the high-melting-point particles that reduce the wettability of the bonding layer are likely to appear on the surface of the reflective film. Since the bonding auxiliary layer is disposed between the bonding layer and the reflective film, the reflective film, whose surface is likely to have high-melting-point particles, is not directly bonded to the bonding layer. In addition, the bonding auxiliary layer has a sintered structure mainly composed of the second metal. Here, the "sintered structure mainly composed of the second metal" refers to a sintered structure whose volume ratio is 80% or more composed of the second metal. This allows the bonding auxiliary layer to be well bonded to the reflective film whose surface has high-melting-point particles. Therefore, the bonding strength between the wavelength conversion member and other members via the bonding layer can be improved.

(2) In the wavelength conversion member of the above embodiment, the bonding auxiliary layer may contain glass. According to this configuration, the bonding auxiliary layer contains glass that has a high affinity with high melting point particles, so that the bonding can be more favorably bonded to the reflective film on whose surface the high melting point particles appear. Therefore, the bonding strength between the wavelength conversion member and other members via the bonding layer can be further improved.

(3) According to another aspect of the present invention, a wavelength conversion device is provided. This wavelength conversion device includes the above-mentioned wavelength conversion member, a heat dissipation member that dissipates heat from the ceramic phosphor to the outside, and a bonding layer that bonds the heat dissipation member to the bonding auxiliary layer, and the bonding layer is formed so as to cover the respective side surfaces of the reflective film and the bonding auxiliary layer. According to this configuration, the reflective film, which is prone to have high-melting-point particles on its surface that reduce the wettability of the bonding layer, is bonded to the bonding layer via the bonding auxiliary layer that can also be bonded well to the bonding layer. As a result, the bonding layer is formed so as to cover the respective side surfaces of the bonding auxiliary layer and the reflective film, thereby improving the bonding strength between the wavelength conversion member and the heat dissipation member.

(4) According to yet another aspect of the present invention, a light source device is provided. This light source device includes the above-mentioned wavelength conversion member and a light source that irradiates the ceramic phosphor with light. According to this configuration, the light source device emits light using a wavelength conversion member in which the bonding strength between the wavelength conversion member and another member via a bonding layer is improved. This allows the state in which the wavelength conversion member and the other member are bonded to each other to be maintained for a long period of time, thereby extending the life of the light source device.

(5) According to yet another aspect of the present invention, a light source device is provided. This light source device includes the above-mentioned wavelength conversion device and a light source that irradiates light to the ceramic phosphor. 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 state in which the wavelength conversion member and the heat dissipation member are bonded together can be maintained for a long period of time due to the improved bonding strength, so that the life of the light source device can be extended while suppressing temperature quenching of the ceramic phosphor.

The present invention can be realized in various forms, such as a device including a wavelength conversion member, a system including a light source device, a method for manufacturing a wavelength conversion member and a light source device, a method for manufacturing a reflective film, etc.

FIG. 2 is a schematic cross-sectional view of a wavelength conversion member according to the first embodiment. 1 is a schematic diagram of a light source device according to a first embodiment. FIG. 2 is an enlarged view of a part of a schematic cross-sectional view of a wavelength conversion device. 11A to 11C are diagrams illustrating the results of an evaluation test of a wavelength conversion member.

First Embodiment
FIG. 1 is a schematic cross-sectional view of a wavelength conversion member 1 of the first embodiment. The wavelength conversion member 1 of this embodiment includes a ceramic phosphor 10, a reflective film 20, and a bonding auxiliary layer 30. When light is incident on the wavelength conversion member 1, the wavelength conversion member 1 emits light of a wavelength different from that of 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 FIG. 1, the stacking direction in which the ceramic phosphor 10, the reflective film 20, and the bonding auxiliary layer 30 are stacked is indicated by a dashed arrow DL. Note that the relationship in size and thickness between the ceramic phosphor 10, the reflective film 20, and the bonding auxiliary layer 30 in FIG. 1 is illustrated to be different from the actual relationship in size or thickness for the sake of convenience of explanation.

The ceramic phosphor 10 is a ceramic sintered body, and in this embodiment, is formed in a substantially cylindrical shape. The ceramic phosphor 10 has an incident surface 11 on which light is incident, and a back surface 12 located on the opposite side of the incident surface 11. The ceramic phosphor 10 converts the wavelength of at least a part of the light incident from the incident surface 11, and emits light of a wavelength different from that of the incident light. The ceramic phosphor 10 is composed of a ceramic sintered body having a fluorescent phase mainly made of fluorescent crystal particles, and a transparent phase mainly made of translucent crystal particles. The transparent phase crystal particles preferably have a composition represented by the chemical formula Al ₂ O ₃ , and the fluorescent phase crystal particles preferably have a composition represented by the chemical formula A ₃ B ₅ O ₁₂ : Ce (so-called garnet structure). "A ₃ B ₅ O ₁₂ : Ce" indicates that Ce is dissolved in A ₃ B ₅ O ₁₂ , and part of the element A is replaced by Ce.

The element A and the element B in the chemical formula A ₃ B ₅ O ₁₂ :Ce are each composed of at least one element selected from the following group of elements:
Element A: Lanthanides other than Sc, Y, and Ce (however, element A may further include Gd)
Element B: Al (however, element B may further contain Ga)
By using a ceramic sintered body as the ceramic phosphor 10, the light is scattered at the interface between the fluorescent phase and the translucent phase, and the angle dependency of the color of the light can be reduced. This improves the uniformity of the color. Note that the material of the ceramic phosphor 10 is not limited to the above-mentioned materials.

The reflective film 20 is disposed on the rear 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 (Al ₂ O ₃ ). 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 ratio of the high-melting-point particles 22 in the reflective film 20 is preferably 3% to 30%. In this embodiment, the reflective film 20 has a thickness of 30 μm to 100 μm. In the reflective film 20, the light transmitted through the ceramic phosphor 10 and the light generated by the ceramic phosphor 10 are reflected by the silver 21. This allows the device including the wavelength conversion member 1 to improve the luminous intensity. 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), etc. 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 is preferably, for example, an oxide having a relatively low reactivity. The material forming the high melting point particles 22 is not limited to alumina, and may be ceramics such as YAG, TiO ₂ , Y ₂ O ₃ , SiO ₂ , Cr ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₂ , AlN, and Si ₃ N ₄ , or metals such as nickel (Ni), tungsten (W), molybdenum (Mo), chromium (Cr), and niobium (Nb).

The bonding auxiliary layer 30 is disposed on the opposite side of the reflective film 20 from the ceramic phosphor 10. The bonding auxiliary layer 30 has a sintered structure mainly composed of silver 31. The term "sintered structure mainly composed of silver 31" refers to a sintered structure in which 80% or more of the volume of the layer is composed of silver 31. For this reason, the bonding auxiliary layer 30 is formed in a porous shape and has a plurality of voids inside. Whether the bonding auxiliary layer 30 has a sintered structure or not is determined by observing an SEM image taken by a scanning electron microscope (SEM). Specifically, when it is observed in the SEM image that the voids are regularly distributed and that a portion of each of the plurality of silver particles remains without melting, the bonding auxiliary layer 30 is determined to have a sintered structure. The bonding auxiliary layer 30 of this embodiment has a porosity of 50% or more, which is the ratio of the area occupied by the voids to the area of the entire SEM image. In this embodiment, the bonding auxiliary layer 30 has a thickness of 30 μm to 100 μm. The metal material that forms 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.

In this embodiment, the bonding auxiliary layer 30 contains glass 32. The glass 32 in this embodiment is an oxide containing silicon (Si) and bismuth (Bi), and is contained in the bonding auxiliary layer 30 at a volume ratio of about several percent. In this embodiment, the volume ratio of the glass 32 contained in the bonding auxiliary layer 30 refers to the ratio of the area of the glass 32 to the total area of the silver 31 and the area of the glass 32 in the above-mentioned 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 the bonding layer 50 described later and the bonding auxiliary layer 30. The glass 32 contained in the bonding auxiliary layer 30 has a high affinity with the high-melting-point particles 22 made of alumina contained in the reflective film 20. This can improve the bonding strength between the reflective film 20 and the bonding auxiliary layer 30.

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

In the light source device 2, the light source 4, such as a light emitting diode (LED) or a semiconductor laser (LD), emits light L1 onto the ceramic phosphor 10 of the wavelength conversion device 3. The ceramic phosphor 10 irradiated with the light L1 emits light of a wavelength different from the light L1. As a result, the wavelength conversion device 3 emits light L2 of a color different from the light L1 emitted by 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 size and thickness relationships of the ceramic phosphor 10, the reflective film 20, the bonding auxiliary layer 30, the heat dissipation member 40, and the bonding layer 50 in FIG. 2 are illustrated to be different from the actual size or thickness relationships for the sake of convenience.

The heat dissipation member 40 is a flat plate-shaped member made of a material having a higher thermal conductivity than the ceramic phosphor 10, such as copper (Cu), a copper-molybdenum alloy, a copper-tungsten alloy, Al, or AlN. The heat dissipation member 40 dissipates the heat of the ceramic phosphor 10, which is 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 materials, and may be a multi-layer member made of the same or different materials. In addition, the surface of the heat dissipation member 40 facing the ceramic phosphor 10 may be plated to enhance adhesion with the bonding layer 50.

The bonding layer 50 is disposed between the wavelength conversion member 1 and the heat dissipation member 40. That is, the bonding auxiliary layer 30 is disposed between the reflective film 20 and the bonding layer 50 disposed between the member (heat dissipation member 40) disposed on the opposite side of the reflective film 20 from the ceramic phosphor 10. 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 so as to cover the respective side surfaces 20a, 30a of the reflective film 20 and the bonding auxiliary layer 30.

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

After the ceramic phosphor 10 is produced, silver powder, alumina powder, an acrylic binder, and a solvent are mixed to produce a paste for the reflective film. The produced paste for the reflective film is applied to the rear surface 12 of the ceramic phosphor 10, dried, and then the ceramic phosphor 10 with the paste for the reflective film applied thereto is heated. By heating the ceramic phosphor 10 with the paste for the reflective film applied thereto, the paste for the reflective film is baked onto the rear surface 12 of the ceramic phosphor 10, and the reflective film 20 is formed on the ceramic phosphor 10.

After forming the reflective film 20 on the ceramic phosphor 10, silver powder, glass powder, a binder, and a solvent are mixed to prepare a paste for the bonding aid layer. The prepared paste for the bonding aid layer is applied to the surface of the reflective film 20 opposite the ceramic phosphor 10, dried, and then heated. This completes the wavelength conversion member 1.

After the wavelength conversion member 1 is completed, 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, for example, in a reflow furnace. This bonds the wavelength conversion member 1 and the heat dissipation member 40, and the wavelength conversion device 3 is completed. 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.

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

Figure 3 is an enlarged view of a part of the schematic cross-sectional view of the wavelength conversion device 3. Figure 3 shows a part of the cross-section along the stacking direction DL in the wavelength conversion device 3. As shown in Figure 3, a plurality of 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 the reflective film 20 is formed 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, and the bonding strength between the ceramic phosphor 10 and the reflective film 20 is improved. Since the high melting point particles 22 have a higher melting point than the silver 21, they do not melt even when the ceramic phosphor 10 to which the paste for the reflective film is applied is heated. As a result, the reaction between the high melting point particles 22 and the ceramic phosphor 10 is suppressed, thereby suppressing the decrease in reflectance, while the high melting point particles 22 are appropriately dispersed in the reflective film 20, thereby suppressing the occurrence of variations in the bonding strength between the ceramic phosphor 10 and the reflective film 20.

The bonding auxiliary layer 30 has a sintered structure mainly composed of silver 31. This allows the bonding auxiliary layer 30 to be well bonded to the reflective film 20 on whose surface the high melting point particles 22 appear. As shown in FIG. 3, the bonding auxiliary layer 30 contains a plurality of glasses 32. The glass 32 contained in the bonding auxiliary layer 30 is formed by melting and solidifying the glass powder contained in the bonding auxiliary layer paste by heating during the manufacture of the wavelength conversion member 1. During the manufacture of the wavelength conversion member 1, the molten glass moves between the silver powder contained in the bonding auxiliary layer paste and is easily bonded to the high melting point particles 22 appearing on the surface 20b of the reflective film 20. This allows the bonding strength between the reflective film 20 and the bonding auxiliary layer 30 to be improved.

Next, we will explain the evaluation test of the wavelength conversion member. In this evaluation test, we evaluated the effect of the presence or absence of a bonding auxiliary layer in the wavelength conversion member on the surface temperature of the ceramic phosphor.

The sample used in this evaluation test was a light source device, and was produced by the above-described manufacturing method of the light source device 2 of this embodiment. In this evaluation test, the reflective film and the bonding auxiliary layer were each produced 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 production: 10 μm
Amount of alumina particles added during production (volume ratio): 15%
・Joining auxiliary layer (thickness 30 μm)
Metal type: Silver Components added to glass during manufacturing: Oxides including Si and Bi Amount of glass added during manufacturing (volume percentage): 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 had a bonding auxiliary layer. Since voids were observed in the bonding auxiliary layer of Sample 2 when a cross-sectional view was observed using a scanning electron microscope, it was confirmed that the bonding auxiliary layer of Sample 2 had a sintered silver structure. The void ratio in the bonding auxiliary layer of Sample 2 was 2%.

In this evaluation test, the surface temperature of the ceramic phosphor when the prepared sample was irradiated with laser light for a certain period of time was measured with a radiation thermometer to obtain the temperature before the test. After obtaining the temperature before the test, a thermal shock test was performed on the sample, in which heating and cooling were repeated a certain number of times. After the thermal shock test, the surface temperature of the ceramic phosphor when irradiated with laser light for a certain period of time was measured with a radiation thermometer again to obtain the temperature after the test. Finally, the ratio of the temperature after the test to the temperature before the test was calculated. Specific information regarding the test conditions of the thermal shock test and the measurement conditions of the surface temperature in this evaluation test are as follows:
Thermal shock test conditions: Maximum temperature: 200°C Minimum temperature: 0°C Holding time: 30 minutes Number of repetitions: 500 times Surface temperature measurement conditions: Laser light wavelength: 450 nm Laser light irradiation diameter: 1 mm diameter
Laser light output: 70 W Irradiation time: 1 minute

Figure 4 is a diagram explaining the results of the evaluation test of the wavelength conversion member. Figure 4 shows the value obtained by multiplying the ratio of the temperature after the test to the temperature before the test by 100 for each of the two types of samples 1 and 2 ("Rtmax (%)" in Figure 4). As shown in Figure 4, the Rtmax was 180% for sample 1 that does not have a bonding auxiliary layer, while the Rtmax was 100% for sample 2 that has a bonding auxiliary layer. The results of sample 1 that does not have a bonding auxiliary layer indicate that the bonding strength between the reflective film and the bonding layer is relatively small, so peeling progresses at the interface between the reflective film and the bonding layer, and the heat dissipation performance is reduced. On the other hand, the results of sample 2 that has a bonding auxiliary layer indicate that the bonding strength between the reflective film and the bonding layer via the bonding auxiliary layer is large, so there is no peeling, and the heat dissipation by the heat dissipation member is sufficient.

According to the wavelength conversion member 1 of this embodiment described above, the reflective film 20 arranged on the ceramic phosphor 10 contains high-melting-point particles 22 having a melting point higher than that of silver 21. Therefore, the bonding strength between the ceramic phosphor 10 and the reflective film 20 is improved, while the high-melting-point particles 22 that reduce the wettability of the bonding layer 50 are likely to appear on the surface of the reflective film 20. Since the bonding auxiliary layer 30 is arranged between the bonding layer 50 and the reflective film 20, the reflective film 20, in which the high-melting-point particles 22 are likely 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 be well bonded to the reflective film 20 in which the high-melting-point particles 22 appear on the surface. Therefore, the bonding strength between the wavelength conversion member 1 via the bonding auxiliary layer 30 and the bonding layer 50 and other members such as the heat dissipation member 40 can be improved.

In addition, 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 therefore formed by heating at a temperature below the melting point of silver 31. In other words, since the temperature for forming the bonding auxiliary layer 30 is below the melting point of silver, when the wavelength conversion member 1 is manufactured, it is possible to prevent the reflective film 20 containing silver that has already been formed from melting again when the bonding auxiliary layer 30 is formed. Therefore, it is possible to prevent a decrease in the reflectance of the reflective film 20 due to remelting.

In addition, according to the wavelength conversion device 3 of this embodiment, the bonding auxiliary layer 30 is disposed 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.

In addition, according to the wavelength conversion member 1 of this embodiment, the bonding auxiliary layer 30 contains glass 32 that has a high affinity with the high melting point particles 22, so that it can be bonded even better to the reflective film 20 on whose surface the high melting point particles 22 appear. 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.

In addition, according to the wavelength conversion member 1 of this embodiment, the glass contained in the bonding auxiliary layer 30 melts during the manufacture of the wavelength conversion member 1 and easily bonds with the high melting point particles 22 contained in the reflective film 20. As a result, there is no glass that reduces the wettability of the bonding layer 50 on the side of the bonding auxiliary layer 30 opposite the reflective film 20, i.e., the side that bonds to the bonding layer 50, so that good bonding with the bonding layer 50 can be achieved.

In addition, according to the wavelength conversion device 3 of this embodiment, the reflective film 20, on whose surface the high melting point particles 22 that reduce the wettability of the bonding layer 50 are likely to appear, is bonded to the bonding layer 50 via the bonding auxiliary layer 30, which can also bond well to the bonding layer 50. As a result, the bonding layer 50 is formed so as 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.

In addition, according to the light source device 2 of this embodiment, light is emitted using the 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 bonded state between the wavelength conversion member 1 and the heat dissipation member 40 is maintained for a long period of time, and the life of the light source device 2 can be extended while suppressing temperature quenching of the ceramic phosphor 10.

<Modifications of this embodiment>
The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the invention. For example, the following modifications are also possible.

[Modification 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 is equal to or higher than the melting point of the second metal so that the reflective film does not remelt when the bonding auxiliary layer is formed. However, when the bonding auxiliary layer is formed, the second metal forms a sintered structure at a temperature lower than the melting point, so this is not limited to this.

[Modification 2]
In the above embodiment, the bonding auxiliary layer contains glass. However, the bonding auxiliary layer does not have to contain glass. Even without glass, the bonding auxiliary layer having a silver sintered structure can be well bonded to the bonding layer while improving the bonding strength with the reflective film.

[Modification 3]
In the above embodiment, the wavelength conversion device 3 includes the wavelength conversion member 1, the bonding layer 50, and the heat dissipation member 40, and the wavelength conversion member 1 includes the ceramic phosphor 10, the reflective film 20, and the bonding auxiliary layer 30. However, the configurations of the wavelength conversion member 1 and the wavelength conversion device 3 are not limited to these. They may also include a sealing film, a plating layer, or the like.

Although this aspect has been described above based on the embodiment and modified examples, the embodiment of the above-mentioned aspect is intended to facilitate understanding of this aspect and does not limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and this aspect includes equivalents. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[Application Example 1]
A wavelength conversion member,
A ceramic phosphor that converts the wavelength of incident light;
a reflective film disposed on the ceramic phosphor and including a first metal that reflects light and high-melting-point particles made of a material having a melting point higher than that of the first metal;
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, the bonding auxiliary layer having a sintered structure mainly composed of a second metal;
A wavelength conversion member characterized by:
[Application Example 2]
The wavelength conversion member according to Application Example 1,
The bonding auxiliary layer includes glass.
A wavelength conversion member characterized by:
[Application Example 3]
A wavelength conversion device,
The wavelength conversion member according to Application Example 1 or 2,
a heat dissipation member that dissipates heat from the ceramic phosphor to the outside;
The bonding layer bonds the heat dissipation member and the bonding auxiliary layer,
The bonding layer is formed so as to cover each side surface of the reflective film and the bonding auxiliary layer.
A wavelength conversion device characterized by:
[Application Example 4]
A light source device,
The wavelength conversion member according to Application Example 1 or 2,
A light source that irradiates the ceramic phosphor with light.
A light source device characterized by:
[Application Example 5]
A light source device,
The wavelength conversion device according to Application Example 3,
A light source that irradiates the ceramic phosphor with light.
A light source device characterized by:

Reference Signs List 1: wavelength conversion member 2: light source device 3: wavelength conversion device 4: light source 10: ceramic phosphor 20: reflective film 20a: side surface (of reflective film) 21: silver 22: high melting point particles 30: bonding auxiliary layer 30a: side surface (of bonding auxiliary layer) 31: silver 32: glass 40: heat dissipation member 50: bonding layer

Claims (5)

A wavelength conversion member,
A ceramic phosphor that converts the wavelength of incident light;
a reflective film disposed on the ceramic phosphor and including a first metal that reflects light and high-melting-point particles made of a material having a melting point higher than that of the first metal;
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, the bonding auxiliary layer having a sintered structure mainly composed of a second metal;
A wavelength conversion member characterized by: The wavelength conversion member according to claim 1 ,
The bonding auxiliary layer includes glass.
A wavelength conversion member characterized by: A wavelength conversion device,
The wavelength conversion member according to claim 1 or 2,
a heat dissipation member that dissipates heat from the ceramic phosphor to the outside;
The bonding layer bonds the heat dissipation member and the bonding auxiliary layer,
The bonding layer is formed so as to cover each side surface of the reflective film and the bonding auxiliary layer.
A wavelength conversion device characterized by: A light source device,
The wavelength conversion member according to claim 1 or 2,
A light source that irradiates the ceramic phosphor with light.
A light source device characterized by: A light source device,
A wavelength conversion device according to claim 3,
A light source that irradiates the ceramic phosphor with light.
A light source device characterized by:

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