Wavelength conversion module, light emission device and method for manufacturing the wavelength conversion module

Abstract

A highly reliable wavelength conversion module is provided. A wavelength conversion module 100 comprises a phosphor element 11 and a translucent substrate 12, which is directly connected to the phosphor element 11, has a higher thermal conductivity than the phosphor element 11, and has a thickness in the range of 100 µm to 600 µm.

Description

Technical area

[0001] The present disclosure relates to a wavelength conversion module, a light emitting device, and a method for manufacturing the wavelength conversion module. State of the art

[0002] In recent years, high-power light sources that convert the wavelength of blue light from a semiconductor laser using a phosphor element have been widely used as light sources for spotlights, various lighting devices, and laser projectors, for example. Since the phosphor element in such a light source generates heat due to wavelength conversion, it is necessary to efficiently dissipate or dissipate the heat generated in the phosphor element. In particular, in a wavelength conversion module used in a light source that uses a semiconductor laser, it is necessary to use a wavelength conversion element with good durability and to efficiently dissipate the heat generated in the wavelength conversion element.

[0003] For example, Patent Document 1 discloses an optical conversion device including a phosphor element excited by excitation light, a first condenser lens having a lens bottom surface to which the phosphor element is bonded and through which the excitation light can enter the phosphor element, and a heat dissipation member disposed on the lens bottom surface around a portion to which the phosphor element is bonded. According to Patent Document 1, the heat generated in the phosphor element can be cooled without a motor, thereby reducing the size and improving reliability. Citation listPatent literature

[0004] Patent Document 1: JP 6737265 B Brief description of the inventionTechnical problem

[0005] However, a light source with higher output power is required, as is a wavelength conversion module with a wavelength conversion element used for such a light source, i to achieve higher reliability.

[0006] Therefore, it is an object of the present disclosure to provide a wavelength conversion module with high reliability, a light emitting device including the wavelength conversion module, and a method for manufacturing the wavelength conversion module. Solution to the problem

[0007] A wavelength conversion module according to the present disclosure comprises a phosphor element and a light-transmitting or transparent substrate directly bonded to the phosphor element, having a higher thermal conductivity than the phosphor element, and having a thickness in a range of 100 µm to 600 µm.

[0008] A light emitting device according to the present disclosure includes the above-mentioned wavelength conversion module and a light source configured to irradiate the wavelength conversion module with light.

[0009] A method of manufacturing a wavelength conversion module according to the present disclosure includes directly bonding a light-transmitting substrate to a phosphor element, and dicing the light-transmitting substrate and the phosphor element that are directly bonded to each other. Advantageous effects of the invention

[0010] The wavelength conversion module and the light-emitting device configured as described above can have higher reliability. The method for manufacturing the wavelength conversion module configured as described above enables the production of a wavelength conversion module with higher reliability. Short description of drawings Fig. 1 is a plan view of a wavelength conversion module according to the present disclosure. Fig. Figure 2A is a cross-sectional view along line AA of the Fig. 1 shown wavelength conversion module. Fig. 2B is an enlarged cross-sectional view of a portion of the cross-sectional view of Fig. 2A. Fig. 3 is a schematic view showing a light emitting device according to the present disclosure. Fig. 4 is a flowchart of a method of manufacturing the wavelength conversion module according to the present disclosure. Fig. 5 is a process cross-sectional view of the method of manufacturing the wavelength conversion module according to the present disclosure, wherein Fig. 5(a) is a process cross-sectional view showing a direct connection step, and Fig. 5(b) is a process cross-sectional view showing a singulation step. Fig. 6 is a characteristic curve showing the relationship between the irradiation power of a blue laser and the light power emitted from a phosphor element with respect to wavelength conversion modules of a first example and a comparative example. Fig. 7 is a characteristic curve showing the relationship between the irradiation power of a blue laser and the light power emitted from a phosphor element with respect to a wavelength conversion module of a second example. Description of embodiments

[0011] Embodiments and examples for carrying out the present disclosure are described below with reference to the drawings. Note that a wavelength conversion module and a light-emitting device described below merely serve to embody the technical concept of the present disclosure, and the present disclosure is not limited to the following unless otherwise specified.

[0012] In the individual drawings, parts with identical functions may be designated by the same reference numerals. In order to more easily explain or understand the main points, the embodiments and examples may be shown separately for convenience. However, partial substitutions or combinations of the configurations shown in different embodiments and examples are possible. In the embodiments and examples described below, descriptions of common features with those already described are omitted, and only the different points are described. In particular, similar actions and effects of similar configurations are not mentioned for each embodiment and example in turn. The size, positional relationship, and the like of components shown in the drawings may be exaggerated for clarity.An end view that shows only a cut surface can be used as a cross-sectional view. Embodiments according to the present disclosure are described in detail below

[0013] The optical conversion device disclosed in Patent Document 1 is configured such that the phosphor element is bonded to the lens bottom surface of the first condenser lens, and at least one edge of the region where the phosphor element is bonded to the lens bottom surface is bonded to the heat dissipation member. The first condenser lens is described as a lens, and Patent Document 1 does not specifically describe the thickness of the first condenser lens.

[0014] In the optical conversion device disclosed in Patent Document 1, when the surface of the phosphor element is irradiated with a laser, the phosphor element is excited by the laser light, the light is converted into light with a wavelength different from the wavelength of the excitation light, and the wavelength-converted light is extracted. When wavelength conversion is performed, the excited phosphor element generates heat, and the temperature of the phosphor element rises. As the temperature of the phosphor element rises, the wavelength conversion efficiency decreases. Therefore, in Patent Document 1, the heat dissipation member is provided to dissipate the heat generated by the phosphor element through the heat dissipation member, thereby preventing the temperature of the phosphor element from rising.Specifically, the phosphor element is disposed at the central part of the lens bottom surface on the opposite side of a convex lens surface, and the heat dissipation member is connected to a lower surface of the phosphor element and the lens bottom surface around the phosphor element to suppress the temperature rise of the phosphor element.

[0015] However, with regard to the optical conversion device of Patent Document 1, although a certain heat dissipation effect is achieved, the heat dissipation property is insufficient. This is because, although part of the heat generated in the phosphor element is transferred to the condenser lens, the heat transferred to the condenser lens cannot be easily transferred to other elements and cannot be easily dissipated, so the heat is likely to be trapped. It is difficult to reduce the size of the heat dissipation element that dissipates heat from the optical conversion device. The present inventors conducted intensive studies with the following findings to provide a wavelength conversion module in which a temperature rise of a phosphor element can be effectively suppressed and its size reduced.

[0016] When the phosphor element is irradiated with excitation light, the area surrounding the surface of the phosphor element is mainly excited, and the excitation light is attenuated as it enters the interior of the phosphor element. As a result, efficient wavelength conversion is unlikely to be achieved in the phosphor element. In other words, heat is mainly generated in the area surrounding the surface of the phosphor element irradiated with the excitation light, and the amount of heat generated decreases as the excitation light penetrates the phosphor element. Therefore, to effectively suppress the temperature rise of the phosphor element, a configuration that can effectively dissipate the heat generated in the area surrounding the surface of the phosphor element is preferable.

[0017] Therefore, in the present disclosure, a light-transmitting substrate with a thermal conductivity higher than the thermal conductivity of the phosphor element is directly bonded to the light-irradiation surface of the phosphor element, so that the heat generated in the vicinity of the light-irradiation surface of the phosphor element can be effectively dissipated. On the other hand, a region that does not contribute to heat dissipation is reduced, thereby reducing the size of the wavelength conversion module. In the present disclosure, the thickness of the light-transmitting substrate is set within a certain range to improve heat dissipation efficiency.

[0018] Considering that heat is mainly generated around the surface of the phosphor element irradiated with the excitation light, and the amount of heat generated decreases as the excitation light moves from the surface to the interior, the thickness of the phosphor element is preferably set within a range where the wavelength conversion efficiency and the heat dissipation effect of the phosphor element can be compatible with each other in the present disclosure. That is, if the thickness of the phosphor element is large, the temperature of the phosphor element rises due to the heat of the high-output excitation light, and the wavelength conversion efficiency of the phosphor element cannot be improved. Even if the heat dissipation element is bonded to the lower surface of the phosphor element, the heat cannot be efficiently transferred to the heat dissipation element.

[0019] If the excitation light is intensely emitted onto a portion of the light irradiation surface of the phosphor element, the conversion efficiency of that portion may decrease because the temperature of that portion rises dramatically, and efficient dissipation of the generated heat may be difficult. Accordingly, the entire light irradiation surface of the phosphor element is preferably irradiated with excitation light of a desired, substantially uniform intensity. However, in the light-transmitting lens-shaped element disclosed in Patent Document 1, the temperature of a portion of the phosphor element may rise dramatically because the excitation light is converged by refraction at the lens.

[0020] Therefore, based on the above findings, in the present disclosure, a light-transmitting member is made into a light-transmitting substrate, and an upper surface of the light-transmitting substrate is made flat, so that heat transfer efficiency in a lateral direction of the light-transmitting member can be increased and heat dissipation property can be improved, and substantially uniform irradiation of the upper surface of the light-transmitting substrate with excitation light and irradiation with a substantially uniform intensity of an entire light irradiation surface of a phosphor element with excitation light are facilitated.

[0021] That is, when the upper surface of the light-transmitting substrate is flat, an optical system is designed to be lightweight so that the flat surface can be substantially uniformly irradiated with light from a light source. Considering that the entire light-irradiation surface of the phosphor element is irradiated with excitation light at a substantially uniform intensity, the thickness of the light-transmitting substrate serving as a path for the excitation light is preferably set within a certain range. Although the light-transmitting substrate is light-transmitting, light attenuation occurs. Therefore, by reducing the thickness of the light-transmitting substrate, attenuation of the light irradiated onto the light-irradiation surface of the phosphor element and a reduction in wavelength conversion efficiency can be suppressed.

[0022] The present disclosure has been made as a result of intensive studies based on the above findings and can efficiently dissipate heat generated in a phosphor element and reduce the size of a wavelength conversion module.

[0023] In particular, a wavelength conversion module 100 comprises a phosphor element 11 and a light-transmitting substrate 12 which is directly bonded to the phosphor element 11, has a thermal conductivity higher than the thermal conductivity of the phosphor element 11, and has a thickness in a range of 100 µm to 600 µm (see Fig. 2A and Fig. 2B). Since the phosphor element 11 is directly bonded to the light-transmitting substrate 12, which has a thermal conductivity higher than the thermal conductivity of the phosphor element 11 and a thickness ranging from 100 μm to 600 μm, the heat generated in the phosphor element 11 can be efficiently dissipated through the light-transmitting substrate 12. The wavelength conversion module 100 of the present disclosure can be used, for example, as a reflection-type wavelength conversion module. In the reflection-type wavelength conversion module, an incident surface onto which excitation light is incident and an emission surface from which wavelength-converted light is emitted are the same surface. The wavelength conversion module 100 can be a transmission-type wavelength conversion module.In the transmission-type wavelength conversion module, an incident surface onto which excitation light is incident and an emission surface from which wavelength-converted light is emitted are opposed to each other. More specific aspects will be discussed in detail below with reference to FIG. Fig. 1 to 2B. - Fluorescent element -

[0024] The Fig. 2A and Fig. The phosphor element 11 shown in FIG. 2B can be excited by light from a light source and emit light having a wavelength different from the wavelength of the light from the light source. The phosphor element 11 is preferably formed of a phosphor. In the present specification, the phosphor element formed of a phosphor implies that inevitable mixing with a component other than the phosphor is not excluded, and the content of the component other than the phosphor is, for example, 5% by volume or less. As an example of the phosphor element 11, a polycrystalline body is suitable, and a sintered compact composed of a rare earth aluminate phosphor having a composition expressed by the following formula (I) is advantageous. The rare earth aluminate phosphor is a chemically and thermally very stable phosphor. (Ln1 - n Ce n)3(Al1 - mM1 m )5O 12 (I)

[0025] (In the above formula (I), Ln is at least one rare earth element selected from the group consisting of Y, La, Lu, Gd and Tb, M1 is at least one element selected from Ga and Sc, and m and n are numbers such that 0 ≤ m ≤ 0.02 and 0.0017 ≤ n ≤ 0.0170, respectively).

[0026] The phosphor element 11 may be a YAG plate formed from a sintered compact of yttrium aluminum garnet, or a LAG plate formed from a sintered compact of lutetium aluminum garnet, as an example of the sintered compact made of the rare earth aluminate phosphor, and is selected depending on the configuration of a projector to be used. The thickness of the phosphor element 11 is described in detail below and may preferably be 200 μm or less, more preferably less than 95 μm, even more preferably less than 80 μm, and even more preferably less than 70 μm. By setting the thickness of the phosphor element 11 within this range, when a heat dissipation member is disposed on a lower surface of the phosphor element 11, heat generated in the vicinity of a surface of the phosphor element 11 can be efficiently transferred to the heat dissipation member.The thickness of the phosphor element 11 is preferably 50 µm or more, for example. By setting the thickness of the phosphor element 11 within this range, high wavelength conversion efficiency can be achieved. The Ce content (mol%) of the phosphor in the phosphor element 11 is calculated by n × 3 × 100 / (3 + 5 + 12) using the Ce substitution ratio n described above and is preferably in a range of 0.025 mol% to 0.255 mol%. Such a Ce content can suppress a decrease in luminous efficiency at high temperatures and is therefore particularly suitable for use in a high-power laser.

[0027] The relative density of the rare earth aluminate sintered compact is in a range of 85% to 99%, preferably 89% or more, more preferably 90% or more, even more preferably 91% or more, and may be even more preferably 92% or more. When the relative density of the rare earth aluminate sintered compact is in a range of 85% to 99%, excitation light incident on the sintered compact is efficiently scattered by cavities, and the scattered light is efficiently wavelength-converted by a crystalline phase, so that the wavelength-converted light can be emitted from the same surface as a surface on which the excitation light is incident.

[0028] The relative density of the rare earth aluminate sintered compact can be calculated from the apparent density of the sintered compact and the true density of the sintered compact according to equation (1). [Math. 1] Relative density (%) of the rare earth aluminate sintered compact = (apparent density of the rare earth aluminate sintered compact) / (true density of the rare earth aluminate sintered compact) × 100

[0029] The apparent density of the rare earth aluminate sintered compact is a value obtained by dividing the mass of the sintered compact by the volume of the sintered compact and can be calculated using equation (2) below. The true density of the rare earth aluminate phosphor can be used as the true density of the rare earth aluminate sintered compact. [Math. 2] Apparent density of the rare earth aluminate sintered compact = (mass (g) of the rare earth aluminate sintered compact) / (volume (Archimedes method) (cm3) of the rare earth aluminate sintered compact)

[0030] The rare earth aluminate sintered compact preferably has a void content in a range of 1% to less than 15%. The void content of the rare earth aluminate sintered compact is a value determined by subtracting the relative density of the sintered compact from 100% and can be calculated according to Equation (3) if necessary. [Math. 3] Porosity (%) of the rare earth aluminate sintered compact = 100% − Relative density (%) of the rare earth aluminate sintered compact

[0031] In the rare earth aluminate sintered compact, the voids are preferentially distributed around the crystalline phase. When the voids are distributed around the crystalline phase, the excitation light incident on the sintered compact is scattered by the voids distributed around the crystalline phase, and the scattered light is efficiently wavelength-converted by the crystalline phase. Thus, the wavelength-converted light can be efficiently emitted from the same surface as the surface on which the excitation light is incident.

[0032] The phosphor element 11 may contain other known phosphors in addition to or instead of the rare earth aluminate phosphor. Other known phosphors include, for example, BSESN-based phosphors (e.g., (Ba,Sr)2 Si5N8 : Eu).

[0033] The phosphor element 11 has, for example, a rectangular, flat shape. The size of the phosphor element 11 in a plan view is, for example, a 1 mm to 6 mm square. When the size is equal to or larger than 1 mm square, the wavelength conversion efficiency of the phosphor element 11 can be improved, and misalignment of the excitation light is unlikely. When the flat area of ​​the phosphor element is twice or more than twice the spot size of the excitation light, misalignment of the excitation light is particularly unlikely. From the viewpoint of simplicity of a manufacturing process, the flat shape of the phosphor element 11 is preferably a rectangular shape. However, the flat shape of the phosphor element 11 is not limited to a rectangular shape, but may be a circular shape, an elliptical shape, or another polygonal shape. - Translucent substrate -

[0034] The light-transmitting substrate 12 has a higher thermal conductivity than the phosphor element 11, allowing part of the heat generated in the phosphor element 11 to be transferred to the light-transmitting substrate 12. The thermal conductivity of the light-transmitting substrate 12 is, for example, 1.2 to 200 times, preferably 1.2 to 5 times, more preferably 1.2 to 4 times the thermal conductivity of the phosphor element 11. The thermal conductivity of the YAG plate used as an example for the phosphor element 11 is about 11.7 W / mK, and the thermal conductivity of the light-transmitting substrate 12 is preferably higher than 11.7 W / mK, and is preferably 15 W / mK or more. Generally, the thermal conductivity is used at room temperature (20 ± 20°C) unless otherwise specified.

[0035] The light-transmitting substrate 12 is transparent so that the phosphor element 11 can properly receive the light from the light source. The term "transparent" in this specification means that 80% or more of the light from the light source is transmitted. A sapphire or diamond substrate is advantageous as the light-transmitting substrate 12 with such thermal conductivity and light transmittance.

[0036] The light-transmitting substrate 12 is in the shape of a flat plate and has a thickness in a range of 100 μm to 600 μm. The thickness of the light-transmitting substrate 12 is preferably 0.6 to 12 times, more preferably 2 to 8 times, the thickness of the phosphor element 11. When the thickness of the light-transmitting substrate 12 is 100 μm or more, the light-transmitting substrate 12 serves as a heat dissipation member that efficiently dissipates heat. When the thickness of the light-transmitting substrate 12 is 600 μm or less, the amount of light emitted from a side surface of the light-transmitting substrate 12 can be reduced, and light can be efficiently extracted from above the light-transmitting substrate 12. An upper surface of the light-transmitting substrate 12 is preferably a flat surface that is not curved like a convex lens.When the upper surface of the light-transmitting substrate 12 is a flat surface, part of the light extracted by the wavelength conversion module 100 is completely reflected between the light-transmitting substrate 12 and the air. Light with an angle of total reflection or greater is returned to the interior of the light-transmitting substrate 12, and part of the light is extracted from the light-transmitting substrate 12 after scattering and reflection. On the other hand, light with an angle smaller than the angle of total reflection is extracted from the light-transmitting substrate 12 unchanged. Thus, since strong light emission is achieved in a narrow range smaller than the angle of total reflection, the light transmitted through the light-transmitting substrate 12 can be efficiently coupled into a second lens of the optical system.When the upper surface of the light-transmitting substrate 12 is shaped like a convex lens, most of the light extracted by the wavelength conversion module 100 can be extracted from the light-transmitting substrate 12. However, the light transmitted through the light-transmitting substrate 12 is emitted while dispersing over a wide angle. Therefore, a large amount of the light emitted from the light-transmitting substrate 12 cannot be coupled into the second lens, resulting in an increase in the proportion of wasted light. In the light-transmitting substrate 12, the ratio of the thinnest part to the thickest part is preferably 0.8 or more, more preferably 0.9 or more, even more preferably 0.98 or more. The light-transmitting substrate 12 may be a light-transmitting substrate with the same thickness.By forming the light-transmitting substrate 12 in the shape of a flat plate and adjusting its thickness within the above-mentioned range, the upper surface of the light-transmitting substrate 12 is easily irradiated with excitation light substantially uniformly, and the entire light irradiation surface of the phosphor element is easily irradiated with excitation light with a substantially uniform intensity, as described above. By adjusting the thickness as described above, the heat generated in the phosphor element 11 can be properly dissipated from the irradiation surface side of the laser-irradiated phosphor element 11 to the light-transmitting substrate 12.

[0037] The light-transmitting substrate 12 is directly bonded to the phosphor element 11. The term "directly bonded" in the present specification refers to an aspect in which the light-transmitting substrate 12 and the phosphor element 11 are in direct contact with each other and bonded together without an adhesive or the like therebetween. That is, when using a high-power laser, if the light-transmitting substrate and the phosphor element are bonded together with an adhesive, the adhesive may burn out. Therefore, it is preferable not to use an adhesive. An anti-reflection film and other layers, which are described below, are not preferably provided between the light-transmitting substrate 12 and the phosphor element 11.When an anti-reflection film or the like is disposed on an upper surface of the phosphor element 11, heat generated on the surface of the phosphor element 11 may be trapped by the anti-reflection film or the like, and the heat may not be dissipated efficiently. On the other hand, in the wavelength conversion module of the present disclosure, since the phosphor element 11 is in direct contact with the high thermal conductivity light-transmitting substrate 12, the heat generated in the phosphor element 11 can be appropriately dissipated to the light-transmitting substrate 12. Although direct contact is described below, a bonding method such as surface activation bonding or atomic diffusion bonding may also be used.By directly contacting the light-transmitting substrate 12 with the phosphor element 11, the heat generated in the vicinity of the irradiation surface of the phosphor element can be efficiently transferred to the light-transmitting substrate 12. Since the light-transmitting substrate 12 has higher thermal conductivity than the phosphor element 11, a region where heat spreads in the horizontal direction is larger in the light-transmitting substrate 12 than in the phosphor element 11. That is, most of the heat generated in the vicinity of the irradiation surface of the phosphor element 11 diffuses to the high thermal conductivity side of the light-transmitting substrate 12, whereupon the heat can efficiently spread in the horizontal direction within the light-transmitting substrate 12.

[0038] The light-transmitting substrate 12 can be diced together with the phosphor element 11 using a dicing blade or a laser beam, as described below in a method for manufacturing the wavelength conversion module. Therefore, the planar shape or planar portion of the light-transmitting substrate 12 can be substantially the same as the planar shape or planar portion of the phosphor element 11. Similar to the phosphor element 11, the light-transmitting substrate 12 can also have a rectangular shape in plan view. The phosphor element 11 and the light-transmitting substrate 12 having substantially the same shape thus contribute to downsizing the wavelength conversion module, and the entire light irradiation surface of the phosphor element 11 can be irradiated with excitation light having a desired substantially uniform intensity.

[0039] As described above, in the wavelength conversion module of the present disclosure, the phosphor element 11 is in direct contact with the light-transmitting substrate 12, which has a higher thermal conductivity than the phosphor element 11 and a thickness in a range of 100 μm to 600 μm. Thus, the heat generated in the phosphor element 11 can be properly dissipated from the irradiation surface of the laser-irradiated phosphor element 11 to the light-transmitting substrate 12. <Andere zusätzliche Konfigurationen>

[0040] As it is in the Fig. 2A and Fig. 2B, the wavelength conversion module may include, in addition to the above-described phosphor element 11 and the light-transmitting substrate 12, a base 30, a connecting member 20 connecting the base 30 and the phosphor element 11, a reflection film 13a, a connecting metal 13b, and an anti-reflection film 14 disposed on the light-transmitting substrate 12. -Base-

[0041] The base 30 may include a base member 31 having a recess 31a, a first metal layer 32 disposed on an upper surface of the base member 31 including an inner surface of the recess 31a, and a second metal layer 33 disposed on the first metal layer 32. The base member 31 is preferably made of copper or a copper alloy in view of heat dissipation and processability. The first metal layer 32 is made of nickel (Ni), for example, and the thickness is preferably in a range of 0.1 µm to 3.0 µm. The second metal layer 33 is gold (Au), for example, and the thickness is preferably in a range of 0.02 µm to 5.0 µm. Furthermore, a third metal layer 34 for adjusting a distance between the base 30 and the phosphor element 11 may be disposed on the second metal layer 33 on a bottom portion of the recess 31a.As an example of the third metal layer 34, silver (Ag) can be used, and the thickness can be adjusted according to the distance between the base 30 and the phosphor element 11. For example, the thickness of the third metal layer 34 is preferably in a range of 0.1 μm to 100 μm, but the third metal layer 34 need not be present. - Connecting element -

[0042] The connecting member 20 connects the base 30 to a member including at least the phosphor element 11. The connecting member 20 includes a metal member 21 and a resin 50. Since the connecting member 20 includes the resin 50, deterioration of the connecting member 20 due to temperature change can be prevented, and reliability can be improved. In the case of silver (Ag) or copper (Cu) with high thermal conductivity, stress-induced migration is likely due to residual stress on the metal surface. On the other hand, by covering the metal surface with a resin, migration of the metal surface can be effectively prevented. The metal member 21 is preferably formed of a material with good thermal conductivity in order to efficiently transfer the heat generated in the phosphor element 11 to the base 30. For example, the metal member 21 preferably includes silver (Ag) or copper (Cu), more preferably silver (Ag).

[0043] As a preferred aspect of the connecting member 20, the connecting member 20 can be disposed on a part of the side surface of the translucent substrate 12. Preferably, the metal part 21 included in the connecting member 20 is disposed on a part of the side surface of the translucent substrate 12. Since the connecting member 20 or the metal part 21 included in the connecting member 20 covers a part of the side surface of the translucent substrate 12, a part of the heat transferred to the translucent substrate 12 can be dissipated from the side surface of the translucent substrate 12 to the base 30 via the connecting member 20. Although the connecting member 20 includes the metal part 21 and the resin 50 as described above, a part of the side surface of the translucent substrate 12 is preferably in contact with the metal part 21 in terms of heat dissipation property.According to such a configuration, the heat generated in the light-transmitting substrate 12 can be effectively dissipated by the metal part 21 with good thermal conductivity.

[0044] In the Fig. 2A and Fig. 2B shows, as an example, an aspect in which the connecting member 20 covers the side surface of the light-transmitting substrate 12. However, the connecting member 20 may also cover the side surface of the light-transmitting substrate 12 and a side surface of the anti-reflection film 14. A part of the connecting member 20 may extend to the outer peripheral edge of an upper surface of the anti-reflection film 14 so that incident light and emitted light are not blocked. - Metal part -

[0045] The metal part 21 is preferably a metal sintered compact with a porous structure including voids. The metal sintered compact with a porous structure as described in the present disclosure is obtained, for example, by firing and sintering a metal paste with a metal powder body. The metal sintered compact with a porous structure includes a metal part with a network structure in which a plurality of metal particles are continuously bonded by fusing at least portions of the adjacent metal powder, and the voids are formed between the adjacent metal powders, excluding the fired portions. Accordingly, the metal sintered compact with a porous structure as described in the present disclosure includes voids between the phosphor element 11 and the base (heat dissipation member), for example, in the wavelength conversion module.

[0046] Furthermore, the term "porous material" generally refers to a material with a large number of pores and is referred to, for example, as a microporous material, mesoporous material, or macroporous material. However, the metal sintered compact in the present disclosure may contain voids of various sizes, for example, depending on the particle size distribution of the metal powder body before sintering. For example, when the metal sintered compact in the present disclosure is used as a connecting member that joins two parts together, voids are also present in a part located between the two parts, making it possible to ensure strength high enough to withstand thermal stress while ensuring a more effective heat transfer path.

[0047] The metal part 21 may include a fillet extending toward a bottom surface of the recess 31a of the base 30, and the fillet may be disposed on at least a portion of the side surface of the light-transmitting substrate 12. Since the metal part 21 covers the side surface of the light-transmitting substrate 12, part of the heat transferred to the light-transmitting substrate 12 can be dissipated from the side surface of the light-transmitting substrate 12 to the base 30 via the metal part 21. The "fillet" described in this specification refers to a portion of the metal part 21 that protrudes outward from the side surfaces of the phosphor element 11 and the light-transmitting substrate 12 and has a substantially triangular cross-sectional shape that increases the cross-sectional area downward from the phosphor element 11 side.

[0048] The metal part 21 may cover the entire side surface of the phosphor element 11. The term "covering" in the present specification refers not only to a covering with direct contact between the metal part 21 and the phosphor element 11, but also to an indirect covering without direct contact between the metal part 21 and the phosphor element 11. According to such a configuration, since the metal part 21 covers the periphery of the phosphor element 11, part of the heat generated in the phosphor element 11 can be dissipated from the side surface of the phosphor element 11 to the base 30 via the metal part 21. The phosphor element 11 and the metal part 21 may be in direct contact with each other.

[0049] In a preferred aspect, the light-transmitting substrate 12 may be in direct contact with the metal member 21. According to such a configuration, part of the heat generated in the light-transmitting substrate 12 can be dissipated from the side surface of the light-transmitting substrate 12 to the base 30 via the metal member 21. In another preferred aspect, the metal member 21 may cover 10% to 100% of the side surface of the light-transmitting substrate 12 in a thickness direction from a lower surface of the light-transmitting substrate 12. Specifically, the metal member 21 may cover a lower part of the light-transmitting substrate 12 from the center of the thickness of the light-transmitting substrate 12 in the thickness direction.

[0050] The metal part 21 may contain spacer particles to ensure that the connecting element 20 has a certain thickness or more. Thus, the thickness of the metal part 21 between the base 30 and the phosphor element 11, i.e., the thickness of the connecting element 20, can be made equal to or thicker than the particle size of the spacer particle. The spacer particles may be made of zirconium particles, glass particles, silicon dioxide particles, or aluminum oxide particles, and are preferably made of zirconium particles. The particle size of the spacer particles is appropriately determined taking into account the distance to be maintained between the base 30 and the phosphor element 11, but is, for example, in a range of 20 µm to 500 µm, preferably in a range of 50 µm to 300 µm, and more preferably in a range of 100 µm to 200 µm. -Resin-

[0051] The connecting element 20 may contain the resin 500 in addition to the metal part 21 to obtain the suitable connecting element 2. The resin 50 increases a connection area with the base 30 to enable a strong connection. The resin 50 preferably comprises a first resin element 51 covering an outer surface of the metal part 21 and second resin elements 52 impregnated into the cavities of the metal sintered compact constituting the metal part 21. By covering the metal part 21 with the first resin element 51, sulfation and oxidation of the metal part 21 can be suppressed. The cavities of the metal sintered compact constituting the metal part 21 are impregnated with the second resin element 52, thereby increasing resistance to thermal stress.As can be seen from the fact that the cavities of the metal sintered compact are impregnated with the second resin elements 52, the connection between the phosphor element 11 and the base 30 is mainly established by the metal part 21. In other words, the volume ratio of the second resin elements 52 is preferably lower than the volume ratio of the metal part 21.

[0052] The main component of the resin 50 (the first resin member 51 and the second resin member 52) is, for example, a thermosetting epoxy resin. A silicone resin or the like can also be used, but the epoxy resin is preferred because the epoxy resin has a high gas barrier property and can shield the metal sintered compact from the outside air after the metal sintered compact is impregnated with it. The thermosetting epoxy resin preferably does not contain halogens such as chlorine. The type of the epoxy resin can be alicyclic, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, hexahydrophthalate diglycidyl ester, or the like, and various epoxy-reactive diluents can be added as liquid products. Among these epoxy resins, the alicyclic epoxy resin is preferable.Because the alicyclic epoxy resin has low viscosity and filling properties, voids are less likely to occur. The glass transition temperature can be increased to 200°C or more, and the glass transition temperature can be easily adjusted according to the required heat resistance temperature. -Particles distributed in the resin-

[0053] The resin 50 may contain dispersed particles 53. The particles 53 are preferably particles contained in a defoamer that effectively suppresses the formation of bubbles during resin filling. A defoamer can be obtained, for example, by mixing and dispersing hydrophilic or hydrophobic particles (powder) in a medium such as silicone oil. In addition to silicone oil, a highly hydrophobic surfactant can also be used as the medium. The former, silicone oil, is an antifoaming defoamer suitable for non-aqueous materials, while the latter, the highly hydrophobic surfactant, is an antifoaming defoamer suitable for aqueous materials. In the present embodiment, silicone oil is preferably used because most resin materials are non-aqueous materials.Hydrophilic silica, hydrophobic silica, or the like can also be used as hydrophilic or hydrophobic particles. As a defoaming agent, there are antifoaming defoamers that can effectively suppress foam formation and antifoaming defoamers that effectively break foam. The antifoaming defoamers are preferably used taking into account the dispersion or the like of the resin material.

[0054] The average particle size of the hydrophilic or hydrophobic particles mixed and dispersed in the medium is appropriately determined taking into account the size of the cavities of an object to be impregnated and the settling of the particles during storage, but is, for example, in a range of 0.001 µm to 20 µm, preferably in a range of 0.01 µm to 10 µm, more preferably in a range of 0.05 µm to 5 µm. The content of the hydrophilic or hydrophobic particles is, for example, in a range of 0.001 parts by weight to 10 parts by weight, preferably in a range of 0.01 parts by weight to 5 parts by weight, more preferably in a range of 0.1 parts by weight to 3 parts by weight, each based on 100 parts by weight of the medium.

[0055] The particles 53 can be contained in both the first resin member 51 and the second resin member 52. However, the second resin members 52 contain almost no particles 53 inside the metal part 21, and the particles 53 are arranged in the resin near the outer surface of the metal part 21. That is, in the second resin member 52, the density of the particles 53 contained in the second resin member 52 near the outer surface of the metal part 21 is higher than the density of the particles 53 contained in the second resin member 52 inside the metal part 21. The density of the particles 53 distributed in the first resin member 51 is higher than the density of the particles 53 distributed in the second resin members 52 inside the metal part 21.

[0056] The dispersed particles 53 function to act on the foam surface when the foam of the resin material for forming the resin 50 reaches the liquid surface during the manufacturing of the wavelength conversion module, thereby destabilizing the foam surface by disrupting the arrangement and suppressing the growth of the foam from the liquid surface. The foam-suppressing function of the resin element of the particles 53 is shown within the first resin element 51, and thus the second resin elements 52 essentially do not need to contain the particles 53. - Reflection film -

[0057] The reflective film 13a may be disposed on the lower surface of the phosphor element 11. The lower surface of the phosphor element 11 refers to a surface opposite to the surface on which the light-transmitting substrate 12 is disposed. The reflective layer 13a may comprise, for example, an Al2O3 layer, a SiO2 layer, an Nb2O5 layer, or a TiO layer, and preferably comprises an Al2O3 layer. The reflective film 13a is a transparent layer and functions to reflect at least a portion of the light from the phosphor element 11 at an interface. Since the reflection of light by the reflective film 13a is a reflection with lower light absorption compared to the reflection of light by a metal, the light can be reflected efficiently. The thickness of the reflective film 13a is preferably in a range of 0.1 μm to 5.0 μm. - Connecting metal

[0058] The connecting metal 13b may be disposed on a lower surface of the reflective film 13a. The lower surface of the reflective film 13a refers to a surface facing the base 30. The connecting metal 13b may be composed, for example, of an Ag film, a multilayer or multiple layers of a Ni film and an Ag film, a multilayer of an Ag film and an Au film, a multilayer of an Al film and an Ag film, an Au film, a multilayer of an Al film and an Au film, or a multilayer in which any metal layer is disposed as a barrier layer for light reflection, adhesion, or heating between the multilayers, and is preferably composed of an Ag film. The thickness of the connecting metal 13b is preferably in a range of 0.1 µm to 100 µm. -Anti-reflective film-

[0059] In a preferred aspect, the anti-reflection film 14 can be arranged on the upper surface of the light-transmitting substrate 12. The upper surface of the light-transmitting substrate 12 is an irradiation surface or an emission surface. The anti-reflection film 14 can be made of, for example, a metal oxide such as SiO2, Nb2O5, or TiO2, or a nitride such as SiN, GaN, or AlN, and is preferably made of SiO2. The anti-reflection film 14 can be made of a single layer or a multilayer, with several of the above-mentioned materials stacked on top of one another. The thickness of the anti-reflection film 14 preferably corresponds to a thickness required for the purpose of an anti-reflection film. In the case of a single layer of SiO2, for example, the thickness of the anti-reflection film 14 is preferably in a range of 0.05 µm to 0.20 µm.

[0060] The outermost surface of the anti-reflection film 14 is preferably an oxide. Since the oxide generally has a large contact angle with the resin, the oxide can reduce the wettability of the resin. Consequently, resin adhesion and contamination of the outermost surface of the anti-reflection film 14 at a light irradiation position and a light emission position can be reduced. The outermost surface of the anti-reflection film 14 is, for example, SiO2.

[0061] Next, the light emitting device including the wavelength conversion module 100 of the present disclosure and the light source that irradiates the wavelength conversion module 100 with light will be described.

[0062] As the light source LD, for example, a high-power blue laser with an emission peak at a wavelength of 380 nm to 500 nm is preferably used. However, the light source LD is not limited to this wavelength; a light source that emits light at a different wavelength may also be used. The wavelength conversion module 100 of the present disclosure is irradiated with light emitted from the light source LD, for example, light with a specific wavelength, via an optical system such as a dichroic mirror M and a lens L. That is, the light source LD is arranged to irradiate the wavelength conversion module 100 of the present disclosure with light.

[0063] In the wavelength conversion module 100, the light-transmitting substrate 12 is disposed on the side of a light-receiving surface that receives light from the light source LD. Therefore, although heat is generated on the light-receiving surface (light irradiation surface) of the phosphor element 11 that receives light from the light source, the heat is easily transferred from the light-receiving surface (light irradiation surface) of the phosphor element 11 to the high-thermal-conductivity light-transmitting substrate 12, the heat can be effectively dissipated through the light-transmitting substrate 12.

[0064] The light emitted from the wavelength conversion module 100 is output via a predetermined optical system (for example, the dichroic mirror M, the lens L, and the like).

[0065] The following is a method of manufacturing the wavelength conversion module of the present disclosure with reference to a Fig. The manufacturing or production process shown in Figure 4 is described.

[0066] The method for manufacturing the wavelength conversion module of the present disclosure includes at least a step of directly bonding a light-transmitting plate to a phosphor plate, and a step of dicing the directly bonded light-transmitting plate and phosphor plate. The planar shape of the dicing light-transmitting substrate and the phosphor element are substantially the same. At least one of a polishing step, a reflective film formation step, and a base bonding step may be provided as an additional step. The steps of the method for manufacturing the wavelength conversion module are described sequentially below. -Direct connection step-

[0067] A phosphor plate 11' and a translucent plate 12' described above are manufactured. As an example, a YAG plate made from a sintered compact is manufactured as the phosphor plate 11', and a sapphire substrate is manufactured as the translucent plate 12'. A sapphire substrate in the form of a flat plate and with a thickness in a range of 100 µm to 600 µm is manufactured. The phosphor plate 11' and the translucent plate can be ground and / or polished to a desired thickness.

[0068] After the phosphor plate 11' and the translucent plate 12' have been prepared, a bonding surface of the phosphor plate 11' and a bonding surface of the translucent plate 12' are irradiated with an ion beam or plasma to activate the bonding surfaces. Subsequently, the activated bonding surfaces are brought into contact with each other and directly bonded together (see Fig. 5(a)). The direct bonding method is not limited to surface activation bonding, but can also be used, for example, for atom diffusion bonding, in which atoms diffuse at a bonding interface. -Polishing step (additional step) -

[0069] After the direct bonding step, the phosphor sheet 11' can be polished to a thickness ranging from 50 μm to 200 μm. The polishing step in the present specification may include both grinding and polishing. From the perspective of heat dissipation performance, the thickness of the phosphor sheet 11' is preferably as thin as possible. However, since the wavelength conversion efficiency of the phosphor element 11 after dicing decreases when the thickness is less than 50 μm, the lower limit of the thickness is set to 50 μm. On the other hand, the thickness of the phosphor sheet 11' is preferably 200 μm or less. This easily transfers heat generated in the vicinity of the irradiation surface of the phosphor element 11 after dicing to the side of the base 30 located under the phosphor element 11, and improves the heat dissipation performance of the entire wavelength conversion module.In the polishing step, the phosphor plate 11' is ground to a target thickness of 10 µm using a #1500 grindstone at a grindstone feed rate of 30 µm / min to 48 µm / min. However, if the target thickness of the phosphor plate 11' is less than 100 µm, grinding is stopped at 100 µm regardless of the target thickness to prevent cracking due to the grinding stress. Subsequently, the phosphor plate 11' is preferably polished to the target thickness using a #22000 grindstone at a grindstone feed rate of 1 µm / min to 10 µm / min. Although the aspect in which the polishing step is performed after the direct bonding step is described above, the phosphor sheet 11' having a thickness in a range of 50 µm to 200 µm may also be prepared in advance before the direct bonding step. - Reflective film formation step (additional step) -

[0070] After the direct bonding step, the reflective film 13a is formed on the phosphor plate 11'. The reflective film 13a is formed by a known film forming method (for example, a sputtering film forming method) to a thickness in a range of 0.1 μm to 5.0 μm. The bonding metal 13b is formed after the reflective film 13a is formed. The bonding metal 13b is selected, for example, from an Ag film, a multilayer of a Ni film and an Ag film, a multilayer of an Ag film and an Au film, a multilayer of an Al film and an Ag film, or an Au film and a multilayer of an Al film and an Au film, and is formed to a thickness in a range of 0.1 μm to 100 μm by a known film forming method (for example, sputtering). An anti-reflective film can also be formed by using a known film forming device (e.g., a film forming apparatus).a sputtering device) on the light-transmitting plate 12'. In the case of a single-layer SiO2, the anti-reflection film is formed, for example, in a range of 0.05 µm to 0.20 µm. The anti-reflection film 14 can be formed in a single layer or in multiple layers. However, as described above, an oxide is advantageous for the outermost surface of the anti-reflection film to reduce contamination by resin adhesion, which will be described later. Preferably, the outermost surface of the anti-reflection film 14 is made of SiO2. -Separation step-

[0071] The directly bonded phosphor plate 11' and translucent plate 12' are singulated with a dicing blade, a laser, or the like. In the method for manufacturing the wavelength conversion module of the present disclosure, since the directly bonded phosphor plate 11' and translucent plate 12' are singulated with, for example, a dicing blade D (see Fig. 5(b)), the flat portion of the phosphor element 11 and the flat portion of the light-transmitting substrate 12 are substantially identical to each other after the singulation. The phosphor element 11 and the light-transmitting substrate 12 have a rectangular, flat shape and a size of, for example, 1 mm to 6 mm square as a result of the singulation. - Basic connection step (additional step) -

[0072] The base joining step includes a base manufacturing step, a joining element applying step, an arranging step, a joining step, and an impregnation step. 1. Basic manufacturing step

[0073] The base manufacturing step is, for example, a step of manufacturing the base 30, which includes the base member 31 having the recess 31a, the first metal layer 32, the second metal layer 33, and the third metal layer 34. A known processing technique can be used to form the recess, and a known film forming method (e.g., a film forming method by sputtering) can be used to form the first to third metal layers. The base 30 is not limited to the above-described example, but a protruding portion may be provided instead of the recess. Any of the first metal layer 32 to the third metal layer 34 may be used, or the metal layer may be omitted. 2. Fastener application step

[0074] First, a metal paste is produced which contains the metal powder body. (1) Production of the metal paste

[0075] In the following description, a case is described where silver particles are used as metal powder, and the metal paste is called silver paste. (1-1) Silver particle production

[0076] The shape of the silver particles to be produced is not particularly limited and can, for example, be substantially spherical or scaly. In this specification, the silver particle is "substantially spherical," meaning that the aspect ratio (a / b), defined by the ratio of a major axis a to a minor axis b of the silver particle, is 2 or less. When the silver particles are "scaly," this means that the aspect ratio is greater than 2. The major axis a and the minor axis b of the silver particles can be measured by image analysis using SEM.

[0077] The silver particles to be produced have an average particle size of, for example, 0.3 µm or more, preferably 0.5 µm or more, more preferably 1 µm or more, even more preferably 2 µm or more. The silver particles have an average particle size of preferably 10 µm or less, more preferably 5 µm or less. When the average particle size is 0.5 µm or more, more preferably 1 µm or more, the silver particles do not aggregate even without forming a protective film such as a resist on the surface of the silver particles, so the protective film does not need to be thermally decomposed, and sintering can be performed at a low temperature. The large particle size of the silver particles improves the flowability of the silver paste. Therefore, if the silver paste has the same flowability (processability), it can contain more silver particles.When the mean particle size is 10 μm or less, preferably 5 μm or less, the melting point decreases due to an increase in the specific surface area of ​​the silver particle, so the sintering temperature can be lowered. The particle size of the silver particle can be measured by a laser diffraction method. In this specification, "mean particle size" refers to a volume-based mean diameter measured by the laser diffraction method (a value at which the integrated volume frequency calculated from the particle size distribution is 50%).

[0078] The content of the silver particles to be produced is preferably 5 mass% or less of silver particles with a particle size of less than 0.3 μm, and more preferably 15 mass% or less of silver particles with a particle size of 0.5 μm or less. The silver particles tend to be sintered at low temperatures as the particle size decreases. In particular, nano-sized silver particles are sintered at a lower temperature than microscopic silver particles. Therefore, a high content of nano-sized silver particles in the silver paste causes sintering to start at a low temperature, and fusion may occur in a state where the silver particles are not sufficiently in contact with each other.

[0079] The silver particles to be produced may have a trace of silver oxide film, sulfur film, etc., on their surface. Since silver is a noble metal, the silver particles themselves are not easily oxidized and are very stable. However, at the nanoscale, silver easily adsorbs sulfur, oxygen, etc., such as from the air, and tends to form a thin film on the surface of the silver particles. The thickness of the oxide film, sulfide film, etc., on the silver particle is preferably 50 nm or less, more preferably 10 nm or less.

[0080] (1-2) Mixing of silver particles and organic solvent. This involves mixing the prepared silver particles and an organic solvent as a dispersion medium. The silver paste may further contain a resin, etc. The content of the silver particles during mixing is preferably 70 mass% or more, more preferably 85 mass% or more. The miscible resin is decomposed by heating and firing, which will be described below, and does not remain in the composite body to be formed. The resin may be, for example, polystyrene (PS) or polymethyl methacrylate (PMMA). Mixing the silver particles with an organic solvent, which is a dispersant, facilitates the application of the silver paste to the surface of the base in a desired thickness. The organic solvent used here may be, for example, an organic solvent or a mixture of two or more types of organic solvents, such as a mixture of diol and ether.The boiling point of the organic solvent is preferably in the range of 150°C to 250°C. If the boiling point is 150°C or higher, atmospheric contamination of the silver particles and the falling off of chips can be prevented by drying before the heating step. If the boiling point is 250°C or lower, the volatilization rate in the heating step is increased, and sintering can be promoted.

[0081] In addition to the silver particles and the dispersion medium, additives such as a dispersant, a surfactant, a viscosity modifier, and a diluent, as well as spacer particles, may be added. The content of the additive in the silver paste may be such that the total amount of the additive is 5 mass% or less, for example, in a range of 0.5 mass% to 3 mass%, based on the amount of silver paste. In particular, by adding spacer particles, the thickness of the metal paste can be controlled with sufficient reproducibility. This enables stable impregnation with the resin, which is advantageous. In the above description, the silver paste prepared using silver particles is described as an example.However, the present embodiment is not limited to the use of the silver paste, but a metal paste consisting of metal particles other than the silver particles, for example, copper particles, may also be used. (2) Applying metal paste to the base

[0082] Here, the metal paste is applied to the base 30. Specifically, the prepared metal paste is applied to the bottom surface of the recess 31a. As a method for applying the metal paste, a known method such as a screen printing method, an offset printing method, an inkjet printing method, a flexographic printing method, a dispenser printing method, a gravure printing method, a stamp printing method, a dispenser, a doctor blade, screen printing, spraying, brushing, and a coating method can be suitably used. The application thickness of the metal paste can be adjusted accordingly depending on the application, etc., and may, for example, be in a range of 1 µm to 1000 µm, preferably in a range of 5 µm to 800 µm, more preferably in a range of 10 µm to 500 µm. 3. Arrangement step

[0083] On the metal paste deposited on the bottom surface of the recess 31a, the separated light-transmitting substrate 12 and the phosphor element 11 are arranged in a direction in which the phosphor element 11 and the metal paste face each other. For example, the separated light-transmitting substrate 12 and the phosphor element 11 are placed on top of the metal paste and pressed so that the metal paste has a predetermined thickness between the phosphor element 11 and the bottom surface of the recess 31a, and the metal paste preferentially creeps up a part of the side surface of the light-transmitting substrate 12. 4. Connection step

[0084] In the bonding step, the metal paste is heated to remove the organic solvent, and the metal powder is melted. Thus, the metal powder body is sintered, and the base 30 and the phosphor element 11 are bonded together by a metal sintered compact with a porous structure containing cavities. Heating and firing can be performed in a reduced atmosphere and subsequently in an oxidizing atmosphere, as needed. (1) Heating temperature(1-1) Heating in a reduced atmosphere

[0085] Heating in a reduced atmosphere is performed as needed as described above and is optional. Heating in a reduced atmosphere removes traces of the oxide film, etc., present on the surface of the metal powder through reduction, thereby exposing metal atoms on the surface of the metal powder to promote surface diffusion of the metal atoms on the metal powder surface. Therefore, sintering of the metal particles at a low temperature can be promoted by subsequent heating in an oxidizing atmosphere.

[0086] The heating in a reduced atmosphere and the heating in an oxidizing atmosphere described below can be carried out in separate devices. However, it is advantageous to carry out the heating in a reduced atmosphere and the heating in an oxidizing atmosphere in the same device, and the heating in a reduced atmosphere and the heating in an oxidizing atmosphere can be carried out sequentially in the same device. The reduced atmosphere is preferably a formic acid-containing atmosphere or a hydrogen-containing atmosphere, and is preferably a mixture of formic acid or hydrogen in an inert gas such as nitrogen. The reduced atmosphere preferably contains formic acid and is preferably a mixture of formic acid with an inert gas such as nitrogen.

[0087] Heating in a reduced atmosphere is carried out, for example, at less than 300°C, preferably 280°C or less, more preferably 260°C or less, even more preferably 200°C or less. The heating temperature in a reduced atmosphere is preferably 150°C or more, more preferably 160°C or more, even more preferably 180°C or more. When the heating temperature is 150°C or more, preferably 160°C or more, even more preferably 180°C or more, the reaction rate of the reduction reaction of the oxide film present on the surface of the silver particle can be increased. The pressure during heating in a reduced atmosphere is not particularly limited and can be, for example, atmospheric pressure. (1-2) Burning in an oxidizing atmosphere

[0088] In this process, the metal particles are fused together by heating and firing them in an oxidizing atmosphere to form a sintered metal compact. The oxidizing atmosphere is preferably an oxygen-containing atmosphere, preferably an atmospheric atmosphere. When the oxidizing atmosphere is an oxygen-containing atmosphere, the oxygen concentration in the atmosphere is preferably in a range of 2% to 21% by volume. The higher the oxygen concentration in the atmosphere, the more the surface diffusion of the metal atoms on the surface of the metal particles is promoted, and the easier it is for the metal particles to fuse together.When the oxygen concentration is 2 volume% or more, melting can be performed at a low heating temperature, and when the oxygen concentration is 21 volume% or less, the heating device does not require a pressurization mechanism, and the process cost can be reduced. (2) Firing temperature

[0089] The firing temperature in an oxidizing atmosphere is, for example, 300°C or less, preferably 280°C or less, more preferably 260°C or less, even more preferably 200°C or less. If heating in a reduced atmosphere is performed before firing in an oxidizing atmosphere, firing at a lower temperature is possible. Firing in an oxidizing atmosphere is preferably carried out at 150°C or more, more preferably 160°C or more. By setting the firing temperature to 150°C or more, preferably 160°C or more, a metal sintered compact with low electrical resistance and good thermal conductivity properties can be formed. Firing in an oxidizing atmosphere can be carried out by pressurization or, for example, atmospheric pressure. 5. Impregnation step

[0090] In the impregnation step, a resin material is first prepared with a defoaming agent containing hydrophilic or hydrophobic particles. The prepared resin material is then defoamed by depressurizing before applying the resin material. For example, the resin material is fed into a syringe, and the syringe is placed in a vacuum defoamer to defoam the resin material before application. Depressurizing and defoaming in this way can efficiently remove bubbles that cannot float due to their extremely small size and low buoyancy. For example, the vacuum level during defoaming is maintained in a range of 10 3 Pa to 10 -3 Pa, preferably in a range of 10 2 Pa to 10 -2 Pa, more preferably in a range of 10 Pa to 10 -1Pa. Furthermore, because the resin material used in this manufacturing process contains a defoamer, large bubbles are suppressed and defoamed even if the pressure is reduced in the defoaming step, and, for example, syringe leakage can be prevented.

[0091] Subsequently, the defoamed resin material is applied to the surface of the sintered metal compact. The amount of resin to be applied is set greater than or equal to the amount of resin when it is introduced into the entire cavities of the sintered metal compact. Specifically, for example, the amount of resin to be applied is set greater than or equal to the volume of the cavities of the sintered metal compact, which is determined based on the sintered density of the sintered metal compact and the total volume of the sintered metal compact. Here, the resin material to be applied preferably has a low viscosity, considering that it is supplied into the cavities of the sintered metal compact, but which allows for a reduction in viscosity. For example, when a sintered metal compact is used as a fastener, the surface of the sintered metal compact to be applied is typically inclined rather than horizontal.In such a case, the applied resin material may spread horizontally and reach an area where the resin material should not be applied, such as a wire pad. It is preferable to devise a measure to suppress the spread of the applied resin material in the horizontal direction. For example, after defoaming, the resin material is applied by syringe into the recess on the outer side of the phosphor element 11, that is, in an area between the side surface of the recess and the surface of the groove.

[0092] Subsequently, the resin material applied to the surface of the metal sintered compact (the surface of the groove) is depressurized to discharge the gas in the cavities, and then the cavities are impregnated with the resin material. The vacuum level at the time of impregnation is appropriately adjusted according to the volume fraction of the cavities and the size of the cavities in the metal sintered compact so that the entire cavities are impregnated with the resin material while suppressing excessive foaming. The vacuum level at the time of impregnation is, for example, in a range of 10 3 Pa to 10 -3 Pa, preferably in a range of 10 2 Pa to 10 -2 Pa, more preferably in a range of 10 Pa to 10 -1Pa. Since a large amount of air partially remains between the phosphor element 11 and the bottom surface of the recess 31a in the resin application step, the air floats upward due to its own buoyancy. Therefore, unlike the defoaming step, the air is partially but not completely removed even at normal pressure, and thus the pressure is preferentially reduced. In this manufacturing method, since the resin material is a defoaming agent containing hydrophilic or hydrophobic particles, even if the resin material is applied and then depressurization is performed, the gas in the voids is defoamed as small bubbles without expanding into large bubbles on the surface of the resin material. In this way, excessive foaming can be suppressed, the gas in the voids can be removed, and scattering of the resin material or unnecessary spreading of the resin material can be suppressed.Furthermore, foaming of the resin material due to the foam contained in the resin material itself can be suppressed because the foam contained in the resin material itself is removed by depressurizing before use. Since the hydrophilic or hydrophobic particles (powder) contained in the defoamer are particles, such particles do not easily penetrate into the central region of the cavities of the sintered metal compact and do not need to penetrate into the central region. That is, even if the resin material remains near the surface of the sintered metal compact to which the resin material is applied, the foam suppressing function or foam breaking function is exhibited by the particles in the vicinity of the surface of the sintered metal compact, and excessive foaming of the resin material is suppressed.

[0093] Finally, the resin material impregnated into the cavities is cured by heating. Thus, the wavelength conversion module of the present embodiment is manufactured. EXAMPLES

[0094] In order to evaluate the effect of the heat dissipation property with respect to the wavelength conversion module including the light-transmitting substrate, wavelength conversion modules of a first example and a comparative example described below were manufactured. <Erstes Beispiel>

[0095] The Fig. The wavelength conversion module shown in Figure 2 includes: Anti-reflection film: SiO2 (110 nm thickness); Translucent substrate: sapphire substrate (1.0 × 1.0 × 0.55 mm, thermal conductivity: 42 W / mK); Phosphor element: YAG sintered compact (1.0 × 1.0 × 0.15 mm, thermal conductivity: 11.7 W / mK); Reflection film: Al O 23 (700 nm thickness); Interconnect metal: Ag (500 nm thickness); Connecting element: Ag sintered material (impregnated with epoxy); and Base: Ni / Au metal layer (partially with Ag) on ​​Cu base element. <vergleichsbeispiel>

[0096] A wavelength conversion module is the same as the wavelength conversion module of the first example, except that the light-transmitting substrate is omitted.

[0097] With respect to the wavelength conversion modules of the first example and the comparative example, the relationship between the irradiation power of a blue laser and the power of the light emitted from the phosphor element was evaluated ( Fig. 6). In Fig. 6, a horizontal axis corresponds to the irradiation power of the blue laser, and a vertical axis corresponds to the power of the fluorescent light emitted by the phosphor element. The power emitted by the phosphor element includes two types of light: blue light and fluorescent light, and the blue light is separated by the dichroic mirror. Therefore, the blue light was not considered in the above evaluation; only the fluorescent light was evaluated.

[0098] According to Fig. 6, the wavelength conversion module of the first example was able to correctly output light from the phosphor element even though the phosphor element was irradiated with a blue laser having an irradiation power of 7.4 W. On the other hand, in the wavelength conversion module of the comparative example, when the phosphor element is irradiated with a blue laser having an irradiation power of 5.9 W or more, the phosphor element deteriorates due to heat, resulting in a reduction in the light output from the phosphor element. According to the evaluation results, it was found that in the wavelength conversion module of the first example, the heat generated in the phosphor element is adequately dissipated by the light-transmitting substrate, and the power of the blue laser that can be emitted to the phosphor element can be improved from 5.9 W to 7.4 W.

[0099] Subsequently, as a wavelength conversion module that can further improve the heat dissipation property, a wavelength conversion module of a second example was manufactured. <Zweites Beispiel>

[0100] The wavelength conversion module is the same as the wavelength conversion module of the first example, except that the phosphor element (YAG sintered compact) is 1.0 × 1.0 × 0.075 mm (that is, the phosphor element is half the thickness of the phosphor element of the first example).

[0101] With respect to the wavelength conversion module of the second example, the relationship between the irradiation power of a blue laser and the light output emitted from the phosphor element was evaluated ( Fig. 7). According to Fig. 7, the wavelength conversion module of the second example was able to adequately emit light from the phosphor element even though the phosphor element was irradiated with a blue laser with an irradiation power of 33 W. That is, the thinner the thickness of the phosphor element, the easier it is to dissipate heat to the light-transmitting substrate.

[0102] The embodiments disclosed herein are illustrative in all respects and are not intended to serve as a basis for a limiting interpretation. Accordingly, the technical scope of the present disclosure is not determined solely by the embodiment described above, but is defined based on the description of the scope of the claims. Furthermore, the technical scope of the present disclosure includes all variations within the meaning and scope that correspond to the scope of the claims. Industrial applicability

[0103] The resin impregnation method according to the present embodiment can be used for mounting a semiconductor element, a submount substrate, or the like. Furthermore, the wavelength conversion module and its manufacturing method can be used for automotive headlights, lighting fixtures, projectors, and the like. List of reference symbols 1 light-emitting device 11 Fluorescent element 11' fluorescent panel 12 Translucent substrate 12' Translucent Panel 13a Reflection film 13b Connecting metal 14 Anti-reflective film 20 connecting element 21 Metal part 30 Base 31 Basic element 31a Deepening 32 First metal layer 33 Second metal layer 34 Third metal layer 50 resin 51 First resin element 52 Second resin element 53 particles 100 wavelength conversion module D Dicing Blade L lens LD light source M Dichroic mirror QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 6737265 B

[0004] < / vergleichsbeispiel>

Claims

[1] Wavelength conversion module, which includes: a phosphor element; and a light-transmitting substrate directly bonded to the phosphor element, having a higher thermal conductivity than the phosphor element, and having a thickness in a range of 100 µm to 600 µm. [2] The wavelength conversion module according to claim 1, wherein the phosphor element comprises a reflection film on a surface opposite to a surface on which the light-transmitting substrate is disposed. [3] The wavelength conversion module according to claim 1 or 2, wherein, in a plan view, a flat surface of the phosphor element and a flat surface of the light-transmitting substrate are substantially the same. [4] The wavelength conversion module according to any one of claims 1 to 3, wherein in a plan view, the phosphor element and the light-transmitting substrate have a rectangular shape. [5] The wavelength conversion module according to any one of claims 1 to 4, wherein a thickness of the phosphor element is in a range of 50 µm to 200 µm. [6] A wavelength conversion module according to any one of claims 1 to 5, further comprising: a base; and a connecting element connecting the base to the phosphor element, wherein the connecting element is arranged on a part of a side surface of the light-transmitting substrate. [7] The wavelength conversion module according to claim 6, wherein the connecting member comprises a metal part. [8] A wavelength conversion module according to claim 6, wherein the connecting element comprises: a metal part with a porous structure; and a resin partially disposed in the metal part with a porous structure. [9] A wavelength conversion module according to any one of claims 1 to 8, wherein the phosphor element is a polycrystalline body. [10] A wavelength conversion module according to any one of claims 1 to 9, wherein the phosphor element is a rare earth aluminate sintered compact having a composition represented by the following formula (I): (Ln 1-n Ce n )3(Al 1-m M 1 m )5O 12 (I) (In the above formula (I), Ln is at least one rare earth element selected from the group consisting of Y, La, Lu, Gd and Tb, M 1 is at least one element selected from Ga and Sc, and m and n are numbers such that 0 ≤ m ≤ 0.02 and 0.0017 ≤ n ≤ 0.0170, respectively). [11] The wavelength conversion module according to claim 10, wherein a Ce content (mol%) of the phosphor element is in a range of 0.025 mol% to 0.255 mol%. [12] The wavelength conversion module according to any one of claims 1 to 11, wherein the thermal conductivity of the light-transmitting substrate is 15 W / mK or more. [13] The wavelength conversion module according to any one of claims 1 to 12, wherein the wavelength conversion module is a reflection type wavelength conversion module. [14] The wavelength conversion module according to any one of claims 1 to 13, wherein the phosphor element is made of a phosphor. [15] Light emitting device comprising: the wavelength conversion module according to any one of claims 1 to 14; and a light source designed to irradiate the wavelength conversion module with light. [16] The light emitting device according to claim 15, wherein the light-transmitting substrate is disposed on a side of the light-receiving surface of the phosphor element which receives the light from the light source. [17] A method of manufacturing a wavelength conversion module, the method comprising: directly bonding a translucent plate to a fluorescent plate; and Separating the light-transmitting plate and the phosphor plate which are directly bonded to each other to obtain a plurality of separated bodies in each of which the light-transmitting substrate and the phosphor element are directly bonded to each other, wherein planar shapes of each of the light-transmitting substrates and each of the phosphor elements are substantially the same. [18] A method for manufacturing a wavelength conversion module according to claim 17, wherein in the step of directly bonding the light-transmitting plate to the phosphor plate, a thickness of the light-transmitting plate is in a range of 100 µm to 600 µm. [19] A method for manufacturing a wavelength conversion module according to claim 17 or 18, wherein in the step of directly bonding the light-transmitting plate to the phosphor plate, the direct bonding is performed by surface activation bonding or atomic diffusion bonding. [20] A method of manufacturing a wavelength conversion module according to any one of claims 17 to 19, further comprising polishing the phosphor plate before the dicing step. [21] A method for manufacturing a wavelength conversion module according to claim 20, wherein in the step of polishing the phosphor sheet, the phosphor sheet is polished to a thickness in a range of 50 µm to 200 µm. [22] A method of manufacturing a wavelength conversion module according to any one of claims 17 to 21, further comprising, prior to the dicing step, forming a reflection film on a surface of the light-transmitting plate opposite to a surface on which the phosphor plate is arranged. [23] A method of manufacturing a wavelength conversion module according to any one of claims 17 to 22, further comprising, after the dicing step, a step of bonding the light-transmitting substrate and the phosphor element, which are directly bonded to each other, to a base. [24] A method for manufacturing a wavelength conversion module according to claim 23, wherein in the step of bonding the light-transmitting substrate and the phosphor element, which are directly bonded to each other, to the base, a part of a side surface of the light-transmitting substrate is covered with a bonding member.

Images