Light emitting device and method of manufacturing the same

Abstract

To improve heat resistance of a light-emitting device.SOLUTION: A light-emitting element including: a semiconductor laminated body having a first surface, a second surface opposite to the first surface, and side surfaces between the first surface and the second surface; and an electrode arranged on the second surface; a light-transmissive member arranged on the first surface, the light-transmissive member having a light exit surface, a light incident surface opposite to the first surface on the side opposite to the light exit surface, and a side surface between the light exit surface and the light incident surface; and a light-reflective coating member covering the light-emitting element and the light-transmissive member, wherein, the covering member includes a base material and a plurality of light-reflective particles contained in the base material, the plurality of light-reflective particles include high-aspect-ratio particles having a first average aspect ratio and low-aspect-ratio particles having a second average aspect ratio lower than the first average aspect ratio, and the high-aspect-ratio particles are unevenly distributed in the covering member such that a concentration of the high-aspect-ratio particles around the light exit surface is higher than a concentration of the high-aspect-ratio particles inside the covering member.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a light emitting device and a method for manufacturing the same. [Background technology]

[0002] Some light-emitting devices, such as LEDs, have a light-emitting element and a light-reflective covering member that covers part of the light-emitting element. For example, Patent Documents 1 and 2 disclose a light-reflective covering member made of a heat-resistant resin, such as a silicone resin, that contains a reflective material containing a white pigment.

[0003] However, there is still room for improvement in the light-reflective covering member in order to improve the performance of the light-emitting device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-216416 [Patent Document 2] Japanese Patent Publication No. 2022-058212 Summary of the Invention [Problem to be solved by the invention]

[0005] One of the objectives of one embodiment of the present disclosure is to provide a light-emitting device with improved performance and a manufacturing method thereof. Another objective of another embodiment is to provide a light-emitting device with improved heat resistance and a manufacturing method thereof. Note that the description of these objectives does not preclude the existence of other objectives. Furthermore, it is not necessary for one embodiment of the present disclosure to solve all of these objectives. Furthermore, it is possible to extract other objectives from the description of the specification, drawings, and claims of the present disclosure. [Means for solving the problem]

[0006] a light-emitting element having a semiconductor laminate including a first surface, a second surface opposite the first surface, and a side surface between the first surface and the second surface; and a pair of electrodes arranged on the second surface; a light-transmitting member arranged on the first surface, the light-transmitting member having a light-emitting surface, a light-incident surface opposite the light-emitting surface and facing the first surface, and a side surface between the light-emitting surface and the light-incident surface; and a light-reflective covering member that covers the light-emitting element and the light-transmitting member, the covering member comprising a base material and a plurality of light-reflective particles contained in the base material, the plurality of light-reflective particles comprising high-aspect ratio particles having a first average aspect ratio and low-aspect ratio particles having a second average aspect ratio lower than the first average aspect ratio, and the high-aspect ratio particles in the covering member are distributed unevenly around the light-emitting surface at a higher concentration than inside the covering member.

[0007] A method for manufacturing a light emitting device according to another aspect of the present disclosure includes the steps of: preparing a support member having a support surface; preparing a light-transmitting member having a light emission surface smaller in area than the support surface, a light incidence surface opposite the light emission surface, and a side surface between the light emission surface and the light incidence surface; placing the light-transmitting member on the support surface with the light emission surface facing the support surface; preparing a light emitting element having a semiconductor laminate including a first surface, a second surface opposite the first surface, and a side surface between the first surface and the second surface, and an electrode disposed on the second surface; the light-transmitting member, the light-emitting element, and the high-aspect-ratio particles are arranged on the support surface so that the side surfaces of the light-transmitting member are exposed and there are voids between the high-aspect-ratio particles; ...transmitting member [Effects of the Invention]

[0008] According to a light-emitting device of one aspect of the present disclosure, it is possible to reduce the occurrence of cracks in the covering member that covers the periphery of the light-emitting surface of the light-transmitting member due to heat generation, etc. Furthermore, according to a manufacturing method for a light-emitting device of another aspect, it is possible to obtain a light-emitting device that can reduce the occurrence of cracks due to shrinkage of the surface of the covering member, etc. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic top view showing a light emitting device according to an embodiment. [Figure 2] 2 is a schematic cross-sectional view with an enlarged view of a main part taken along line II-II in FIG. 1. [Figure 3] FIG. 2 is a schematic enlarged view of a coating member made of linear particles. [Figure 4] FIG. 2 is a schematic enlarged view of a coating member made of plate-like particles. [Figure 5] FIG. 2 is a schematic cross-sectional view showing how spherical particles enter gaps between plate-like particles. [Figure 6] FIG. 2 is a schematic perspective view showing the length, width, and height of a plate-like particle. [Figure 7] 5A to 5C are schematic cross-sectional views illustrating a manufacturing process of the light emitting device according to the embodiment. [Figure 8] 5A to 5C are schematic cross-sectional views illustrating a manufacturing process of the light emitting device according to the embodiment. [Figure 9] 1 is a schematic cross-sectional view showing a light emitting device according to an embodiment. [Figure 10] 5A to 5C are schematic cross-sectional views illustrating a manufacturing process of the light emitting device according to the embodiment. [Figure 11] 10 is an SEM photograph showing the top surface of a covering member of a light emitting device according to an example. [Figure 12] 3 is an SEM photograph showing the region indicated by the dashed line in FIG. 2. [Figure 13] 3 is an SEM photograph showing the region indicated by the dashed dotted line in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, each embodiment of the present disclosure will be described with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "upper," "lower," and other terms including these terms) may be used as necessary. However, the use of these terms is intended to facilitate understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present disclosure. Furthermore, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components.

[0011] Furthermore, the embodiments described below are illustrative examples of the technical concepts of the present disclosure and are not intended to limit the present disclosure. Furthermore, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended for illustrative purposes only and are not intended to limit the scope of the present disclosure. Furthermore, the content described in one embodiment or example may also be applicable to other embodiments or examples. Furthermore, the size, positional relationship, etc. of components shown in the drawings may be exaggerated for clarity. In addition, to avoid overly complex drawings, schematic diagrams may be used in which some elements are omitted, or end views showing only the cut surface may be used as cross-sectional views. On the other hand, for materials whose form changes during processing, such as resin materials, for example, materials that are liquid before curing and solid after curing, the same reference numerals are used both before and after curing.

[0012] A light-emitting device 100 according to an embodiment is shown in FIGS. 1 and 2. In these figures, FIG. 1 is a top view of the light-emitting device 100 according to the embodiment, and FIG. 2 is a cross-sectional view with an enlarged view of a main portion taken along line II-II in FIG. 1. As shown in FIGS. 1 and 2, the light-emitting device 100 includes a light-emitting element 10, a light-transmitting member 20, an electrode 40, and a covering member 30. As shown in FIG. 1, the light-emitting device 100 has a rectangular shape when viewed from above. The covering member 30 is disposed so as to cover the side surfaces of the light-emitting element 10 and the light-transmitting member 20. The light-transmitting member 20 includes a light-incident surface through which light from the light-emitting element is incident and a light-exiting surface opposite the light-incident surface. The covering member 30 includes a base material and a plurality of light-reflective particles contained in the base material. The light-reflective particles include high-aspect-ratio particles 31, such as plate-shaped particles, and low-aspect-ratio particles 32, which have a lower aspect ratio than the high-aspect-ratio particles 31. The high aspect ratio particles 31 are located at a higher concentration around the light emitting surface than inside the covering member, which can reduce cracks in the covering member.

[0013] (light-emitting element) The light-emitting element 10 includes a semiconductor stack 14 and an electrode 40. As shown in FIG. 2 , the semiconductor stack 14 has a first surface 11, a second surface 12 opposite to the first surface 11, and a side surface 13 between the first surface 11 and the second surface 12.

[0014] The semiconductor stack 14 includes, for example, an n-type semiconductor layer, a p-type semiconductor layer, and a light-emitting layer disposed between the n-type semiconductor layer and the p-type semiconductor layer. The light-emitting element 10 includes a growth substrate (for example, a sapphire substrate) for growing a semiconductor layer on a first surface 11 of the semiconductor stack 14 opposite to a second surface 12 on which the electrode 40 is disposed. However, the semiconductor stack 14 does not necessarily include a growth substrate. The peak wavelength of light emitted by the semiconductor stack 14 is, for example, in the range of 260 nm to 630 nm. The light-emitting element 10 emits, for example, ultraviolet light or visible light.

[0015] The light emitting element 10 has a pair of positive and negative electrodes 40 on the second surface 12 of the semiconductor laminate 14. The side surface 13 of the semiconductor laminate 14 and the side surfaces of the pair of electrodes 40 are covered with a covering member 30 as shown in FIG.

[0016] (Translucent member) The light-transmitting member 20 is disposed on the first surface 11 of the semiconductor laminate 14 of the light-emitting element 10. The light-transmitting member 20 has a light-emitting surface 21, a light-incident surface 22 opposite the light-emitting surface 21, and a side surface 23 between the light-emitting surface 21 and the light-incident surface 22. The light-incident surface 22 faces the first surface 11 of the light-emitting element 10. The light-transmitting member 20 has an area equal to or larger than the area of ​​the first surface of the semiconductor laminate 14 of the light-emitting element 10. The light-emitting surface 21 of the light-transmitting member 20 is exposed from the covering member 30. The light-emitting surface 21 is formed flush with the surface of the covering member 30.

[0017] The light-transmitting member 20 is made of a material having light-transmitting properties. The light-transmitting member 20 can be made of a resin material or an inorganic material.

[0018] A resin material, an inorganic material, or a combination thereof can be used for the light-transmitting member 20. The light-transmitting member 20 preferably has a transmittance of 60% or more, more preferably 70% or more, and even more preferably 80% or more, for light of the peak wavelength emitted from the light-emitting element 10.

[0019] Examples of resin materials used for the light-transmitting member 20 include thermosetting resins such as silicone resin, silicone-modified resin, epoxy resin, and phenolic resin, and thermoplastic resins such as polycarbonate resin, acrylic resin, methylpentene resin, and polynorbornene resin. Silicone resin, which has excellent light resistance and heat resistance, is particularly suitable. The light-transmitting member 20 may be made of inorganic materials such as silicon oxide and aluminum oxide. Alternatively, the light-transmitting member 20 may be made of glass such as alkali-free glass, soda glass, soda-lime glass, borosilicate glass, aluminosilicate glass, quartz glass, and low-alkali borosilicate glass.

[0020] The light-transmitting member 20 may be composed of only these light-transmitting members, or may be composed of these light-transmitting members as a base material containing phosphors and / or light scattering agents that are excited by light from the light-emitting element and convert it into light of a different wavelength. By including phosphors, a light-emitting device that can emit white light can be obtained. Alternatively, a sintered body in which only phosphor particles are sintered can be used without using the above light-transmitting members, or a sintered body in which a mixture of phosphor particles and particles of aluminum oxide, silicon oxide, or the like is sintered.

[0021] A light-transmitting member containing a wavelength conversion material such as a phosphor generates heat when it receives light from a light-emitting element and converts the wavelength. As a result, the light-transmitting member becomes a heat source, and in combination with the heat generated by the light-emitting element, it heats the covering member, which may cause cracks or the like. In response to this, by distributing high-aspect-ratio particles 31 such as plate-like particles unevenly on the surface side of the covering member 30 as described above, it is possible to improve heat resistance and reduce the occurrence of cracks or the like.

[0022] Examples of phosphors that can be used include yttrium-aluminum-garnet phosphors, lutetium-aluminum-garnet phosphors, terbium-aluminum-garnet phosphors, CCA phosphors, SAE phosphors, chlorosilicate phosphors, silicate phosphors, oxynitride phosphors such as β-sialon phosphors and α-sialon phosphors, nitride phosphors such as LSN phosphors, BSESN phosphors, SLA phosphors, CASN phosphors and SCASN phosphors, fluoride phosphors such as KSF phosphors, KSAF phosphors and MGF phosphors, quantum dots with a perovskite structure, II-VI quantum dots, III-V quantum dots, and quantum dots with a chalcopyrite structure.

[0023] Examples of light scattering agents that can be used include particles of titanium oxide, silicon oxide, aluminum oxide, zinc oxide, magnesium oxide, zirconium oxide, yttrium oxide, calcium fluoride, magnesium fluoride, niobium pentoxide, barium titanate, tantalum pentoxide, barium sulfate, or glass.

[0024] The light-transmitting member 20 can be joined to the light-emitting element 10 using a light-transmitting joining member. The joining member is disposed only between the light-emitting element and the light-transmitting member. Alternatively, the light-emitting element 10 and the light-transmitting member 20 can be directly joined by a direct joining method or the like without using a joining member.

[0025] (Covering material) The covering member 30 covers the light-emitting element 10 and the translucent member 20. The covering member 30 is light-reflective. In this embodiment, the covering member 30 covers the light-emitting element 10 and the translucent member 20, exposing the lower surface of the electrode 40 of the light-emitting element 10 and the light-emitting surface 21 on the upper surface of the translucent member 20. Here, "covering" refers not only to a state in which the covering member 30 is disposed in contact with the light-emitting element 10 and / or the translucent member 20, but also to a state in which the covering member 30 is disposed between the light-emitting element 10 and / or the translucent member 20 and another member is interposed between the covering member 30 and the light-emitting element 10 and / or the translucent member 20. In this disclosure, expressions such as "cover," "covering," and "covered" also refer to a state similar to "covering." Note that when another member, such as a bonding member as shown in FIG. 9, is disposed between the side surface 13 of the light-emitting element 10 and the covering member 30, the inner surface of the covering member 30 facing the side surface 13 of the light-emitting element 10 may have an inclined surface that moves away from the side surface 13 of the light-emitting element 10 as it moves from the second surface to the first surface of the light-emitting element 10 in a cross-sectional view. This inclined surface may be, for example, linear or curved in cross section.

[0026] The light emitting surface 21, which is the upper surface of the light-transmitting member 20 exposed from the covering member 30, becomes the light emitting region of the light emitting device 100. Note that the light emitting device does not necessarily have to include a light-transmitting member. When a light-transmitting member is not provided, the covering member is disposed so that, for example, the first surface of the light emitting element and the lower surface of the electrode are exposed. In this case, the first surface of the light emitting element becomes the light emitting region.

[0027] The covering member 30 includes a base material and a plurality of light-reflective particles contained in the base material. Specific examples of the base material include thermosetting resins such as silicone resin, silicone-modified resin, epoxy resin, and phenolic resin, and thermoplastic resins such as polycarbonate resin, acrylic resin, methylpentene resin, and polynorbornene resin. Alternatively, an inorganic-organic hybrid material including an inorganic material such as polysilazane can be used.

[0028] (light-reflective particles) The plurality of light-reflective particles include high-aspect-ratio particles 31 having a first average aspect ratio and low-aspect-ratio particles 32 having a second average aspect ratio lower than the first average aspect ratio. The high-aspect-ratio particles 31 in the covering member 30 are unevenly distributed so that the concentration is higher around the light-emitting surface 21 than inside the covering member 30. This configuration can reduce the occurrence of cracks due to heat generation or the like in the covering member 30 that covers the periphery of the light-emitting surface 21 of the light-transmitting member 20.

[0029] (high aspect ratio particles) In this embodiment, in addition to spherical particles, high aspect ratio particles 31 are provided. Examples of the high aspect ratio particles 31 include linear particles as shown in FIG. 3. Examples of the high aspect ratio particles 31 include plate-like particles as shown in FIG. 4. Furthermore, the distribution of these high aspect ratio particles 31 is adjusted so that they are unevenly distributed so that the concentration is higher around the light emitting surface 21 than inside the covering member 30. This arrangement reduces deterioration of optical properties. Furthermore, by unevenly distributing them on the surface of the covering member 30, the high aspect ratio particles 31 support each other, strengthening their bonds and improving strength, which reduces the occurrence of cracks.

[0030] In the present disclosure, a plate-like particle refers to a particle having a main surface like a plate when viewed from above, with a thickness in the Z direction that is shorter than the length of the main surface, i.e., the length in the X direction or Y direction, as shown in the schematic diagram of Figure 6. Note that while the shape of the main surface is rectangular in Figure 4, it is not limited thereto and may be any shape, such as a polygonal, circular, or elliptical shape. Furthermore, a linear particle refers to a thin, linear or rod-like particle, as shown in Figure 3.

[0031] The high aspect ratio particles 31 may be made of boron nitride or aluminum oxide, which allows the light from the light emitting element 10 to be reflected efficiently.

[0032] (low aspect ratio particles) Furthermore, gaps GP are provided between the high aspect ratio particles 31. It is preferable to interpose low aspect ratio particles 32 in these gaps GP, as shown in Fig. 5. With this configuration, it is possible to ensure that the light-transmitting member 20 exhibits light reflectivity.

[0033] In the present disclosure, the low aspect ratio particles 32 refer to aggregated particles with a small aspect ratio. The low aspect ratio particles 32 may be spherical, polyhedral such as hexahedron or octahedron, or a modified shape of these.

[0034] Furthermore, the high aspect ratio particles 31 or the low aspect ratio particles 32 may have irregularities on their surfaces.

[0035] The distribution of the low aspect ratio particles 32 in the covering member 30 is preferably generally uniform except for the surface or the interface with other members. That is, the covering member 30 has a region (first region) that includes only low aspect ratio particles 32 as light-reflecting particles, and a region (second region) that includes both high aspect ratio particles 31 and low aspect ratio particles 32.

[0036] The average particle size of the low aspect ratio particles 32 is preferably 0.6 μm or more and 43 μm or less. The low aspect ratio particles 32 can be made of the same materials as the high aspect ratio particles 31, such as boron nitride and aluminum oxide. The low aspect ratio particles 32 can be made of materials such as titanium oxide, zinc oxide, tantalum oxide, niobium oxide, zirconia oxide, and aluminum oxide.

[0037] The high aspect ratio particles 31 have a first average aspect ratio. In contrast, the low aspect ratio particles 32 have a second average aspect ratio lower than the first average aspect ratio. Here, the aspect ratio is the ratio of the longest dimension to the shortest dimension among the dimensions of the particle in the x, y, and z directions, as shown in FIG. 6 . In the plate-like particles described above, the aspect ratio is the length of one side (x or y direction) divided by the thickness (z direction). Furthermore, the high aspect ratio particles 31 preferably have a first average aspect ratio of 10 to 70. This allows the high aspect ratio particles 31, having a high average aspect ratio, to be arranged around the light-emitting surface 21 of the light-transmitting member 20, thereby improving heat resistance, light resistance, and the like and reducing the occurrence of cracks. On the other hand, the low aspect ratio particles 32 preferably have a second average aspect ratio of 1 to 10.

[0038] The average aspect ratio of the light-reflective particles can be calculated, for example, by the following method. The average aspect ratio of the light-reflective particles is calculated by measuring the thickness and width of the light-reflective particles contained in the covering member 30 in a cross section of the light-emitting device 100. First, a cross section that passes through the center of the light-emitting region of the light-emitting device 100 and is approximately perpendicular to the light-emitting surface is exposed. The cross section is exposed by cutting the light-emitting device 100.

[0039] Next, the exposed cross section is mirror-polished. The mirror-polished cross section is photographed using a scanning electron microscope (SEM), the cross sections of the light-reflective particles are extracted, and a measurement area containing approximately 1,000 cross sections of the light-reflective particles is selected. The number of pixels of the microscope is set to approximately 20 million, and the magnification is set to 500 to 3,000 times. In this specification, the cross section of the light-reflective particle is a plane approximately perpendicular to one main surface 31a and / or the other main surface 31b of the light-reflective particle, as shown in FIG. 6. Due to their shape, plate-shaped light-reflective particles tend to be arranged in the covering member 30 so that their main surfaces 31a or 31b face each other and overlap. Therefore, by appropriately selecting the cross section of the light-emitting device 100 to be exposed, the cross sections of the light-reflective particles can be appropriately extracted using the SEM.

[0040] Next, the width (the longitudinal length of the cross section of the light-reflecting material) and thickness (the lateral length of the cross section of the light-reflecting material) of each extracted light-reflective particle are measured one by one using image analysis software, and the average value of the width relative to the thickness is calculated. The average value of the measured values ​​of 100 light-reflective particles is then taken as the average aspect ratio.

[0041] When the light-reflective particles are made of boron nitride, the average aspect ratio of the light-reflective particles is, for example, 16.5 to 19.2. When the light-reflective particles are made of alumina, the average aspect ratio of the light-reflective particles is, for example, 10 to 70.

[0042] The average particle size of the light-reflective particles is 0.6 μm or more and 43 μm or less. Here, the fusion of the light-reflective particle powder and the silica powder during the heating process and the elution of the light-reflective particle powder into the alkaline solution during the heating process are minimal. Therefore, the shape and dimensions of the light-reflective particle powder are substantially identical to the shape and dimensions of the light-reflective particles contained in the coating member 30 formed through the heating process. Therefore, the average particle size of the light-reflective particles is calculated by measuring the particle size of the light-reflective particle powder using the following method.

[0043] The particle size of the light-reflective particle powder is calculated using, for example, a tabletop microscope "TM4000PlusII" manufactured by Hitachi High-Technologies Corporation or a scanning electron microscope "JSM-IT200" manufactured by JEOL Ltd. First, one side of a double-sided carbon tape is attached to the specimen stage of the microscope, and then the light-reflective particle powder is placed on the other side of the double-sided tape. The microscope's pixel count is set to 1.23 million pixels, and the magnification is set to 1000 to 2000 times to acquire images of 100 light-reflective particle powder (particles). Then, the particle size of each particle is measured using image analysis software. In this specification, the particle size of the light-reflective particle powder is the maximum length (width) of the length (width) when viewed from the main surface 31a or 31b of the light-reflective particle. Next, the median diameter of the measured particles is calculated, and this calculated value is taken as the average particle size of the light-reflective particles. The particle size of the powder of light-reflective particles may be calculated by extracting a cross section of the coating member 30 using an SEM and measuring it using image analysis software.

[0044] When the light-reflective particles are made of boron nitride, the average particle size of the light-reflective particles is, for example, 6 μm to 43 μm, and when the light-reflective particles are made of alumina, the average particle size of the light-reflective particles is, for example, 0.6 μm to 10 μm.

[0045] (outer area) As shown in FIG. 2 , the light incident surface 22 of the light-transmitting member 20 has an outer peripheral region 24 that does not overlap with the light emitting element 10 in top view. In the covering member 30 that contacts this outer peripheral region 24, the high aspect ratio particles 31 are unevenly distributed so that the concentration is higher than inside the covering member 30. In other words, the high aspect ratio particles 31 are unevenly distributed only on the upper surface side of the covering member 30, and no high aspect ratio particles 31 are present inside the covering member 30. This arrangement reinforces the covering member 30 around the light incident surface 22 of the light-transmitting member 20, reducing the occurrence of cracks. This is particularly effective when the light-transmitting member 20 generates heat.

[0046] 2, the thickness of the first region 34 including the high aspect ratio particles 31 on the upper surface side is designed depending on the required heat resistance, i.e., the output of the light-emitting element 10 and the type and / or amount of the wavelength conversion material included in the light-transmitting member 20. For example, the thickness is set to a depth of 2 μm to 50 μm from the surface of the covering member 30.

[0047] Furthermore, it is preferable that the distribution of the high aspect ratio particles 31 in the covering member 30 covering the second surface 12 of the light emitting element 10, other than the region where the pair of electrodes 40 is provided, is unevenly distributed at a higher concentration than in portions farther from the light emitting element and further from the surface. This arrangement reduces the occurrence of cracks in the covering member 30 covering the second surface 12 of the light emitting element 10 on the bottom side of the light emitting device 100. In FIG. 2, the thickness of the second region 35 containing the high aspect ratio particles 31 in the covering member 30 at the interface with the second surface 12 of the light emitting element 10 is also designed according to the required heat resistance, similar to the first region 34. Preferably, the thickness is approximately the same as that of the first region 34, with a depth of 2 μm to 50 μm.

[0048] Furthermore, the light-reflective particles such as the high-aspect-ratio particles 31 and / or the low-aspect-ratio particles 32 may be primary particles or secondary particles formed by aggregation of two or more primary particles. Furthermore, primary particles and secondary particles may be mixed.

[0049] In addition, the light emitting device may have a joining member 50 disposed on the side surface of the light-transmitting member 20. Such an example is shown in FIG.

[0050] In the light-emitting device 200 shown in FIG. 9, a bonding member 50 is disposed along the periphery of the interface between the light incident surface 22 of the light-transmitting member 20 and the first surface 11 of the light-emitting element 10. The bonding member 50 has a slope extending from the side surface 13 of the light-emitting element 10 to the light incident surface 22 of the light-transmitting member 20. The bonding member 50 is preferably light-transmitting. By providing such a light-transmitting member 20, light leaking from the side surface 13 of the light-emitting element 10 can be guided to the light-transmitting member 20 via the bonding member 50, thereby improving the light extraction efficiency. A light-transmitting material, such as a silicone resin or a silazane-based compound, can be used for the bonding member 50.

[0051] 2 and 7 to 8 can be used as a manufacturing method for the light emitting device 200 according to the second embodiment. Here, as shown in FIG. 10, with the stacked body 1 configured upside down, an uncured bonding member 50 is placed around the periphery of the light emitting element 10 placed on the light incident surface 22 of the light-transmitting member 20. The uncured liquid bonding member 50 creeps up the side surface 13 of the light emitting element 10, forming an inclined surface. After the bonding member 50 is cured, high aspect ratio particles 31 are placed on the upper surface of the bonding member 50 and in the vicinity thereof, and gaps are formed between adjacent high aspect ratio particles 31.

[0052] [Method of manufacturing a light-emitting device] A method for manufacturing the light emitting device 100 will now be described with reference to Fig. 2 and Figs. 7 to 8. First, a support member 60 having a support surface 61 is prepared as shown in Fig. 7. Examples of the support member 60 include polyimide, polyethylene terephthalate (PET), etc. as a base material, and a tape or the like using a heat-resistant material such as acrylic or silicone as an adhesive on the surface of such a base material can be used. The support member 60 can have an adhesive support surface 61.

[0053] A light-transmitting member 20 is prepared. This light-transmitting member 20 has a light-emitting surface 21 having an area smaller than that of the support surface 61, a light-incident surface 22 opposite to the light-emitting surface 21, and a side surface 23 between the light-emitting surface 21 and the light-incident surface 22.

[0054] Next, the light-transmitting member 20 is placed on the support surface 61 with the light-emitting surface 21 facing the support surface 61 .

[0055] Meanwhile, a light-emitting element 10 is prepared. A semiconductor laminate 14 of the light-emitting element 10 has a first surface 11, a second surface 12 opposite to the first surface 11, and a side surface 13 between the first surface 11 and the second surface 12.

[0056] Then, the light emitting element 10 is placed so that the first surface 11 thereof faces the light incident surface 22 of the light-transmitting member 20. In this manner, the laminate 1 is formed on the support surface 61.

[0057] A covering member is placed on the laminate 1 on the support surface 61. First, high-aspect ratio particles 31 having a first average aspect ratio are placed. Specifically, the high-aspect ratio particles 31 are placed so that the side surface 23 of the light-transmitting member 20 is exposed and gaps GP are formed between the high-aspect ratio particles 31. The high-aspect ratio particles 31 can be placed in powder form, or they can be placed by dispersing them in a solvent and then removing the solvent. The high-aspect ratio particles can be placed, for example, by filling a syringe or the like with the high-aspect ratio particles and sprinkling them in small amounts while vibrating. Alternatively, they can be placed by preparing a mixed solution in which the high-aspect ratio particles are dispersed in a solvent and applying the mixed solution by spraying. Furthermore, if it is desired to remove the high-aspect ratio particles placed on the light-emitting element or the light-transmitting member, the support member 60 is inverted so that it faces up and vibration is applied. If the particles were placed using a solvent, the particles are inverted after the solvent is removed. This allows the high aspect ratio particles held on the adhesive support surface 61 to be held as they are, while the high aspect ratio particles placed on the light emitting element or the light-transmitting member can be removed.

[0058] A mixed material is prepared. The mixed material includes an uncured base material and a plurality of light-reflective particles contained in the base material, the low-aspect-ratio particles 32 having a second average aspect ratio lower than the first average aspect ratio. Typically, the mixed material is a resin material before curing. The mixed material is not limited to resin, and a silazane adhesive material or the like may also be used.

[0059] 8, this mixed member is placed on the laminate 1 and the high aspect ratio particles 31. At this time, the base material and low aspect ratio particles 32 in the mixed member enter the voids GP of the high aspect ratio particles 31. Thereafter, the mixed member is cured to form the covering member 30.

[0060] Finally, the covering member 30 is cut at desired positions to obtain the light emitting device 100 as shown in Fig. 2. In this way, it is possible to obtain the light emitting device 100 that can reduce the occurrence of cracks due to shrinkage of the surface of the covering member 30.

[0061] [Example] As an example, a light-emitting device containing unevenly distributed high-aspect-ratio particles 31 was fabricated. First, a wafer sheet with a diameter of 10 cm was prepared as a support member, and multiple light-transmitting members were placed on its upper surface at 0.4 mm intervals. Each light-transmitting member was 1150 μm × 1150 μm and 180 μm thick. A sintered YAG phosphor was used as the wavelength conversion member for the light-transmitting member. Next, uncured silicone resin was placed on the light-transmitting member using a dispenser. A light-emitting element was then placed on the uncured silicone resin. Each light-emitting element included a semiconductor laminate having a first surface, a second surface opposite the first surface, and a side surface between the first and second surfaces, and a pair of electrodes formed on the second surface. The semiconductor laminate included a gallium nitride-based semiconductor layer stacked on a sapphire substrate, with electrodes made of, for example, silver or copper. The light-emitting element measured 1 mm × 1 mm in top view. The thickness of the semiconductor laminate was 0.15 mm, and the thickness of the electrode was 0.55 mm. The light-emitting element was positioned with the electrode facing up.

[0062] Next, boron nitride particles were prepared as high-aspect ratio particles. The boron nitride particles were mainly plate-shaped, with a length of 0.6 μm to 43 μm and a width of 0.6 μm to 43 μm, and an aspect ratio of approximately 10 or more. The high-aspect ratio particles were filled into a syringe and supplied in small amounts by sprinkling them with vibration. The high-aspect ratio particles were arranged so as to cover the wafer sheet, light-emitting element, and translucent member. The high-aspect ratio particles were arranged so as to leave gaps between them.

[0063] Next, a resin member containing titanium oxide and silicon oxide as low aspect ratios in uncured silicone resin was prepared, with the titanium oxide content being 23.5 wt % and the silicon oxide content being 55 wt %.

[0064] This resin member was placed to cover the wafer sheet, the light-emitting element, and the translucent member. It was placed so that it filled the gaps between the high-aspect-ratio particles. The resin member was also placed to cover the electrodes of the light-emitting element. The assembly was placed in a heating device and heated at 150°C for 4 hours to harden the resin member. This resulted in the formation of a coating member containing high-aspect-ratio particles and low-aspect-ratio particles inside the resin member. Next, the resin member was ground using a grindstone until the electrodes of the light-emitting element were exposed. Finally, it was cut using a dicer to obtain a light-emitting device measuring 1.45 mm in length, 1.45 mm in width, and 380 mm in thickness.

[0065] As a comparative example, a light emitting device containing no plate-like particles was fabricated by the same process as in the example, except that a mixture containing no high aspect ratio particles was used instead of the mixture used in the example.

[0066] The surfaces and cross sections of the light-emitting devices according to Example 1 and Comparative Example 1 obtained in this manner were measured by SEM, and the results are shown in FIGS. 11 to 13. FIG. 11 is an SEM photograph showing the plane of the covering member 30 of the light-emitting device according to Example 1. For the SEM, a Hitachi High-Technologies Corporation tabletop microscope, Miniscope (registered trademark) TM4000PlusII, was used, and images were taken at an acceleration voltage of 15 kV, a focal length of 6.3 mm, and a magnification of 1200x. As shown in FIG. 11, it was confirmed that there were numerous high-aspect-ratio particles 31 having various planar shapes, and that low-aspect-ratio particles 32 were present in the gaps between them.

[0067] As shown in FIG. 8, the light-transmitting member, light-emitting element, and covering member adhered to the support member 60 were ground using a cross-section polishing machine (Auto Met 250 manufactured by BUEHLER) to expose the electrodes 40. As shown in FIG. 2, the surface side of the covering member 30 (FIG. 12) and the interface between the light-transmitting member and the covering member 30 (FIG. 13) were imaged, as indicated by the dashed-line frame in FIG. 2. The image in FIG. 13 was taken using a JEOL JSM-IT200 SEM with an acceleration voltage of 15 kV, a focal length of 11.2 mm, a Standard PC of 50.0, and a BED-C of 5000x magnification. As shown in FIG. 12, the covering member 30 had a first region 34 approximately 10 μm thick from its surface.

[0068] Furthermore, as shown in Figure 13, it was confirmed that a large number of high aspect ratio particles 31 were present at the interface between the translucent member and the covering member 30, and that a third region 36 was formed in which low aspect ratio particles 32 were interposed in the gaps between them.

[0069] The above describes preferred embodiments in detail, but the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0070] The present disclosure can also be implemented in the following manner.

[0071] [Section 1] The front page and a second surface opposite the first surface; and a semiconductor stack having a side surface between the first surface and the second surface; a light-emitting element having a pair of electrodes disposed on the second surface; a light-transmitting member disposed on the first surface, a light exit surface; a light incident surface opposite the light exit surface and facing the first surface; a side surface between the light exit surface and the light incident surface; The light-transmitting member having a light-reflective covering member that covers the light-emitting element and the light-transmitting member; A light emitting device comprising: The covering member is A base material and a plurality of light-reflective particles contained in the base material; Equipped with The plurality of light-reflective particles are high aspect ratio particles having a first average aspect ratio; low aspect ratio particles having a second average aspect ratio lower than the first average aspect ratio; Equipped with The light emitting device has a distribution of the high aspect ratio particles in the covering member such that the high aspect ratio particles are unevenly distributed around the light emitting surface at a higher concentration than inside the covering member. With the above configuration, it is possible to reduce the occurrence of cracks due to heat generation or the like in the covering member that covers the periphery of the light exit surface of the light-transmitting member.

[0072] [Section 2] There are voids between the high aspect ratio particles, Item 2. The light emitting device according to item 1, wherein the low aspect ratio particles are interposed in the voids. With the above configuration, it is possible to ensure that the light-transmitting member exhibits light reflectivity.

[0073] [Section 3] Item 2. The light emitting device according to item 1, wherein the low aspect ratio particles are distributed in the covering member in a generally uniform manner. With the above-described configuration, the low aspect ratio particles are not unevenly distributed within the coating member, and the coating member can exhibit uniform light reflectivity.

[0074] [Section 4] Item 2. The light emitting device according to item 1, wherein the high aspect ratio particles are not present inside the covering member. With the above configuration, it is possible to reinforce the covering member around the light exit surface of the light-transmitting member to reduce the occurrence of cracks, while eliminating high aspect ratio particles inside the covering member to reduce deterioration of optical characteristics.

[0075] [Section 5] the light incident surface of the light-transmitting member has an outer peripheral region that does not overlap with the light-emitting element in a top view, Item 2. The light emitting device according to item 1, wherein the high aspect ratio particles are unevenly distributed in the covering member in contact with the outer circumferential region at a higher concentration than in the interior of the covering member. With the above configuration, it is possible to reduce the occurrence of cracks in the covering member that covers the outer edge region of the light incident surface of the light-transmitting member.

[0076] [Section 6] the covering member covers the second surface of the light-emitting element and the peripheries of the pair of electrodes, Item 2. The light-emitting device according to item 1, wherein the high aspect ratio particles are unevenly distributed in a higher concentration in the second surface of the covering member than in the region where the pair of electrodes are provided, compared to the inside of the covering member. With the above configuration, it is possible to reduce the occurrence of cracks in the covering member that covers the second element surface of the light emitting element.

[0077] [Section 7] Item 7. The light emitting device according to any one of items 1 to 6, wherein the high aspect ratio particles have an average aspect ratio of 10 to 70. With the above configuration, high aspect ratio particles having a high average aspect ratio are arranged around the light exit surface of the light-transmitting member, thereby making it possible to improve heat resistance and light resistance and reduce the occurrence of cracks.

[0078] [Section 8] Item 7. The light emitting device according to any one of items 1 to 6, wherein the high aspect ratio particles are boron nitride or aluminum oxide. With the above configuration, the brightness of the light emitted from the light exit surface can be improved.

[0079] [Section 9] Item 7. The light emitting device according to any one of items 1 to 6, wherein the light-transmitting member includes a wavelength conversion member.

[0080] [Section 10] providing a support member having a support surface; preparing a light-transmitting member having a light exit surface having an area smaller than that of the support surface, a light incident surface opposite to the light exit surface, and a side surface between the light exit surface and the light incident surface; placing the light-transmitting member on the support surface with the light exit surface facing the support surface; A step of preparing a light-emitting element having a semiconductor laminate including a first surface, a second surface opposite to the first surface, and a side surface between the first surface and the second surface, and a pair of electrodes disposed on the second surface; placing the light emitting element with the light incident surface and the first surface facing each other; a step of arranging, on the support surface, a plurality of light-reflective particles, the high-aspect-ratio particles having a first average aspect ratio, so that the side surfaces of the light-transmitting member are exposed and so that gaps are formed between the high-aspect-ratio particles; preparing a mixture including a liquid base material and low aspect ratio particles having a second average aspect ratio lower than the first average aspect ratio as the plurality of light-reflective particles contained in the base material; a step of covering the light-transmitting member, the light-emitting element, and the high-aspect-ratio particles and disposing the mixed member in the gap; A method for manufacturing a light emitting device, comprising: This makes it possible to obtain a light emitting device that can reduce the occurrence of cracks due to shrinkage or the like on the surface of the covering member.

[0081] [Section 11] Item 11. The method for manufacturing a light emitting device according to item 10, further comprising the step of arranging a bonding member around the interface between the light transmissive member and the light emitting element. [Industrial Applicability]

[0082] The light-emitting device and its manufacturing method according to the present disclosure can be suitably used for backlights and light-emitting devices for liquid crystal displays that use semiconductor light-emitting elements such as LEDs and LDs, surface-emitting devices, and in-vehicle light sources, etc. For example, the light-emitting device can be suitably used for displays, smartphones, tablets, in-vehicle monitors, and screens such as those for HMDs and smart glasses. [Explanation of symbols]

[0083] 100, 200, 300...light-emitting devices 1...Laminate 10...Light emitting element 11…Front page 12…Second side 13...Side 14...Semiconductor laminate 20…Translucent member 21...Light exit surface 22...Light incidence surface 23...Side 24...Outer area 30...Covering member 31...high aspect ratio particle; 31a...one main surface; 31b...other main surface 32...Low aspect ratio particles 34…First area 35…Second area 36...Third area 40...Electrode 50... Joint material 60...Support member 61...Support surface GP…Void

Claims

1. The front page and a second surface opposite the first surface; and a semiconductor stack having a side surface between the first surface and the second surface; a pair of electrodes disposed on the second surface; a light-emitting element having a light-transmitting member disposed on the first surface, a light exit surface; a light incident surface opposite the light exit surface and facing the first surface; a side surface between the light exit surface and the light incident surface; The light-transmitting member having a light-reflective covering member that covers the light-emitting element and the light-transmitting member; A light emitting device comprising: The covering member is A base material and a plurality of light-reflective particles contained in the base material; Equipped with The plurality of light-reflective particles are high aspect ratio particles having a first average aspect ratio; low aspect ratio particles having a second average aspect ratio lower than the first average aspect ratio; Equipped with The light emitting device, wherein the high aspect ratio particles are unevenly distributed in the covering member at a higher concentration around the light exit surface than inside the covering member.

2. There are voids between the high aspect ratio particles, The light-emitting device according to claim 1 , wherein the low aspect ratio particles are interposed in the voids.

3. The light emitting device according to claim 1 , wherein the distribution of the low aspect ratio particles in the covering member is generally uniform.

4. The light emitting device according to claim 1 , wherein the high aspect ratio particles are not present inside the covering member.

5. the light incident surface of the light-transmitting member has an outer peripheral region that does not overlap with the light-emitting element in a top view, 2. The light emitting device according to claim 1, wherein the high aspect ratio particles are unevenly distributed in a higher concentration in the covering member that contacts the outer peripheral region than in the interior of the covering member. Not inside.

6. the covering member covers the second surface of the light-emitting element and the peripheries of the pair of electrodes, 2. The light-emitting device according to claim 1, wherein the high aspect ratio particles are distributed in a higher concentration in the second surface of the covering member in a region other than the region where the pair of electrodes are provided than in the interior of the covering member.

7. 7. The light-emitting device according to claim 1, wherein the high aspect ratio particles have an average aspect ratio of 10 to 70.

8. The light emitting device according to any one of claims 1 to 6, wherein the high aspect ratio particles are boron nitride or aluminum oxide.

9. 7. The light emitting device according to claim 1, wherein the light-transmitting member includes a wavelength conversion member.

10. providing a support member having a support surface; preparing a light-transmitting member having a light exit surface having an area smaller than that of the support surface, a light incident surface opposite to the light exit surface, and a side surface between the light exit surface and the light incident surface; placing the light-transmitting member on the support surface with the light exit surface facing the support surface; A step of preparing a light-emitting element having a semiconductor laminate including a first surface, a second surface opposite to the first surface, and a side surface between the first surface and the second surface, and an electrode disposed on the second surface; placing the light emitting element with the light incident surface and the first surface facing each other; a step of arranging, on the support surface, a plurality of light-reflective particles, the high-aspect-ratio particles having a first average aspect ratio, so that the side surfaces of the light-transmitting member are exposed and so that gaps are formed between the high-aspect-ratio particles; preparing a mixture including a liquid base material and low aspect ratio particles having a second average aspect ratio lower than the first average aspect ratio as the plurality of light-reflective particles contained in the base material; a step of covering the light-transmitting member, the light-emitting element, and the high-aspect-ratio particles and disposing the mixed member in the gap; A method for manufacturing a light emitting device, comprising:

11. The method for manufacturing a light emitting device according to claim 10 , further comprising the step of arranging a bonding member around an interface between the light-transmitting member and the light emitting element.

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