Light-emitting device, method for manufacturing the light-emitting device, light-reflecting material, and irradiation device

Abstract

To provide a light-reflecting material, a light-emitting device, and a manufacturing method thereof, which can suppress deterioration of a light-reflecting resin body and improve long-term reliability.SOLUTION: A light-emitting device according to the present invention includes a substrate, a light-emitting element arranged on the substrate, and a translucent thermosetting resin material arranged around the light-emitting element. The resin material has a plurality of closed spaces each holding a resin body.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a light-emitting device, a method for manufacturing a light-emitting device, a light-reflecting material, and an irradiation device.

Background Art

[0002] As a small light-emitting device using a light-emitting element such as a light-emitting diode (LED) as a light source, a light-emitting device including a mounting substrate, a light-emitting element disposed on the mounting substrate, and a light-reflective resin body disposed so as to cover a side surface of the light-emitting element is known.

[0003] For example, Patent Document 1 discloses an optoelectronic semiconductor module including a support, an optoelectronic semiconductor chip disposed on the support, a cover body attached to a radiation main surface of the optoelectronic semiconductor chip, and a reflective casting material covering side surfaces of the optoelectronic semiconductor chip and the cover body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the optoelectronic semiconductor module disclosed in Patent Document 1, a transparent silicone material in which reflective particles made of titanium oxide are embedded is used as a casting material. However, it is known that the resin decomposes due to the photocatalytic action of titanium oxide contained in the casting material. Titanium oxide in the casting material exhibits a photocatalytic action by light from an optoelectronic semiconductor chip or a cover body, which may accelerate the deterioration of a resin such as a silicone material, resulting in yellowing, cracking, and resin loss due to depolymerization of the silicone material. As a result, the long-term reliability of the optical characteristics in the optoelectronic semiconductor module may be impaired.

[0006] In addition, when the concentration of reflective particles such as metal particles in the silicone material is increased to improve the reflection characteristics of the casting material, the elastic modulus of the cured silicone material decreases, cracks in the silicone material and peeling from a support body or the like occur, and the long-term reliability of the optoelectronic semiconductor module may be impaired.

[0007] The present invention has been made in view of the above points, and an object thereof is to provide a light-emitting device, a method for manufacturing a light-emitting device, a light-reflecting material, and an irradiation device capable of suppressing deterioration of a light-reflective resin body and improving long-term reliability.

Means for Solving the Problems

[0008] The light-emitting device according to the present invention includes a substrate, a light-emitting element disposed on the substrate, and a resin material made of a light-transmitting thermosetting resin disposed around the light-emitting element, and the resin material is characterized by having a plurality of closed spaces each holding a resin body.

[0009] Further, a method for manufacturing a light-emitting device according to the present invention is a method for manufacturing a light-emitting device including a substrate, a light-emitting element disposed on the substrate, and a wavelength converter disposed on the upper surface of the light-emitting element, the method including: a dispersion step of dispersing a resin body having a film containing a higher alcohol into a resin material made of a light-transmissive thermosetting resin; a resin material placement step of placing the resin material around the light-emitting element on the substrate; and a heat treatment step of heating and curing the resin material and vaporizing the higher alcohol to form a closed space in the resin material.

[0010] Further, a method for manufacturing a light-emitting device according to the present invention is a method for manufacturing a light-emitting device including a substrate and a light-emitting element disposed on the substrate, the method including: a dispersion step of dispersing thermally expandable particles into a resin material made of a light-transmissive thermosetting resin; a resin material placement step of placing the resin material around the light-emitting element on the substrate; and a heat treatment step of heating and curing the resin material and expanding the thermally expandable particles to form a closed space in the resin material.

[0011] Further, a light reflection material according to the present invention is characterized by being made of a light-transmissive thermosetting resin having a plurality of closed spaces each holding a resin body.

[0012] Further, an irradiation device according to the present invention includes a light source and a light reflection material provided at a position where light emitted from the light source is incident, the light reflection material being characterized by being made of a light-transmissive thermosetting resin having a plurality of closed spaces each holding a resin body. BRIEF DESCRIPTION OF THE DRAWINGS

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described in detail. In the following description and the accompanying drawings, substantially the same or equivalent parts are denoted by the same reference numerals.

Embodiment

[0015] With reference to FIGS. 1 to 3, the configuration of the light-emitting device 100 according to Example 1 will be described.

[0016] FIG. 1 is a top view of the light-emitting device 100 according to Example 1. Further, FIG. 2 is a cross-sectional view taken along line 2-2 of the light-emitting device 100 shown in FIG. 1.

[0017] The light-emitting device 100 includes a substrate 10 having a concave cavity on its upper surface and a first wiring 15 and a second wiring 17 formed on the bottom surface of the cavity, a light-emitting element 20 disposed on the first wiring 15, and a wavelength converter 40 disposed on the upper surface of the light-emitting element 20. Further, the light-emitting device 100 has a resin material 60 that fills the cavity.

[0018] The substrate 10 is, for example, a substrate made of a ceramic such as aluminum nitride (AlN), silicon nitride (SiN), or alumina (Al2O3) having high thermal conductivity. Further, the substrate 10 is composed of, for example, a flat plate portion 11 and a frame portion 13 having the same outer peripheral shape as the upper surface of the flat plate portion 11 and having an opening penetrating from the upper surface to the lower surface at the inner edge portion. That is, the substrate 10 has a concave cavity with the upper surface of the flat plate portion 11 as the bottom and composed of the upper surface of the flat plate portion 11 and the inner side surface of the frame portion 13.

[0019] In the first embodiment, the flat plate portion 11 and the frame portion 13 are integrally formed. That is, the substrate 10 is a substrate formed by processing a single base material. Note that the substrate 10 may be such that the flat plate portion 11 and the frame portion 13 are separately formed and the flat plate portion 11 and the frame portion 13 are joined via an adhesive or the like. Also, in that case, the flat plate portion 11 and the frame portion 13 may be made of separate members.

[0020] The first wiring 15 and the second wiring 17 are formed on the substrate 10 so as to be spaced apart from each other. The first wiring 15 and the second wiring 17 include first and second internal wirings 15I and 17I formed on the upper surface of the flat plate portion 11, that is, the bottom surface of the cavity of the substrate 10, first and second through wirings 15H and 17H formed so as to penetrate from the upper surface to the lower surface of the flat plate portion 11, and first and second external wirings 15O and 17O formed on the lower surface of the flat plate portion 11. The first and second internal wirings 15I and 17I and the first and second external wirings 15O and 17O are electrically connected by the first and second through wirings 15H and 17H.

[0021] The first wiring 15 and the second wiring 17 are, for example, metal wirings made of a metal such as a silver alloy or copper (Cu). Also, the first wiring 15 and the second wiring 17 have a nickel / gold (Ni / Au) metal film formed on the surface.

[0022] Further, the first internal wiring 15I functions as an element mounting portion on which the light-emitting element 20 is mounted on its upper surface. Also, each of the first and second external wirings 15O and 17O functions as a mounting electrode when mounted on the mounting substrate. That is, in the substrate 10, the bottom surface of the cavity in which the first and second internal wirings 15I and 17I are formed functions as the element mounting surface of the light-emitting device 100, and the lower surface of the substrate 10 functions as the mounting surface of the light-emitting device 100 on the mounting substrate. Also, the cavity formation surface, which is the upper surface of the substrate 10, functions as the light emission surface of the light-emitting device 100.

[0023] The light-emitting element 20 is a light-emitting element such as a light-emitting diode (LED) element mounted on the first wiring 15 of the substrate 10. In other words, the light-emitting device 100 includes the light-emitting element 20 arranged on the substrate 10.

[0024] The light-emitting element 20 has a structure in which, for example, a p-type semiconductor layer, an active layer, a semiconductor layer (not shown) composed of an n-type semiconductor layer, and a reflective electrode composed of a plurality of metal layers are bonded together on a support substrate mainly made of a conductive semiconductor such as silicon. The semiconductor layer is laminated, for example, in the order of the reflective electrode, p-type semiconductor layer, active layer, and n-type semiconductor layer from the upper surface of the support substrate via a conductive bonding member. In the first embodiment, the p-type semiconductor layer, the light-emitting layer, and the n-type semiconductor layer are nitride semiconductors mainly made of, for example, gallium nitride (GaN), etc., and are blue LEDs that emit blue light from a light-emitting layer having a multiple quantum well structure. Also, the upper surface of the n-type semiconductor layer is the upper surface of the semiconductor layer and functions as the light emission surface of the light-emitting element 20.

[0025] Further, the n-type semiconductor layer of the semiconductor layer is electrically connected to the support substrate of the light-emitting element 20, and the lower surface of the light-emitting element 20 functions as a cathode electrode. The cathode electrode, which is the lower surface of the light-emitting element 20, is electrically connected to the first internal wiring 15I via a conductive element bonding layer 30.

[0026] On the upper surface of the light-emitting element 20, an electrode pad 25 formed separately from the semiconductor layer is formed. The electrode pad 25 is electrically connected to the p-type semiconductor layer of the semiconductor layer and functions as the anode electrode of the light-emitting element 20. Further, the electrode pad 25 is electrically connected to the second internal wiring 17I via a conductive bonding wire BW made of, for example, gold (Au). That is, in the light-emitting device 100, the first external wiring 15O functions as the cathode electrode of the light-emitting device 100, and the second external wiring 17O functions as the anode electrode of the light-emitting device 100.

[0027] The element bonding layer 30 is, for example, a conductive adhesive. The element bonding layer 30 is made of, for example, a paste in which alloy particles of gold-tin (Au-Sn) are mixed as a raw material. The paste is applied to the first internal wiring 15I, and the cathode electrode of the light-emitting element 20 is placed on the upper surface of the paste so as to be in contact therewith and heat-treated.

[0028] By this heat treatment, the Au-Sn particles contained in the paste are melted and eutectic reaction occurs with the Au layer on the surface of the first internal wiring 15I, and the light-emitting element 20 and the first internal wiring 15I are eutectically bonded. Note that the material of the element bonding layer 30 is not limited to the Au-Sn paste, and materials such as solder paste and silver paste may be used.

[0029] The wavelength converter 40 is disposed on the light-emitting element 20 via an adhesive layer 50. The wavelength converter 40 contains phosphor particles that wavelength-convert part or all of the light emitted from the light-emitting element 20. The wavelength converter 40 is, for example, a sintered body containing phosphor particles mainly made of yttrium aluminum garnet (YAG:Ce, Y3Al5O 12 :Ce) doped with cerium (Ce), and a ceramic binder such as alumina (Al2O3) that transmits the emitted light of the light-emitting element 20 and the emitted light of the phosphor particles. In the first embodiment, the wavelength converter 40 is a wavelength converter that wavelength-converts part of the blue light emitted by the light-emitting element 20 with the phosphor particles and emits white light.

[0030] The adhesive layer 50 is an adhesive made of a light-transmitting resin material that transmits the light emitted from the light-emitting element 20 and the light emitted from the wavelength converter 40. The adhesive layer 50 is a thermosetting resin such as a silicone resin, for example.

[0031] The light emitted from the light-emitting element 20 enters the wavelength converter 40 from the lower surface of the wavelength converter 40 through the adhesive layer 50, is wavelength-converted inside the wavelength converter 40, and exits the light-emitting device 100 from the upper surface of the wavelength converter 40. That is, the lower surface of the wavelength converter 40 functions as a light-receiving surface that receives the light emitted from the light-emitting element 20 through the adhesive layer 50, and the upper surface thereof functions as a light-emitting surface of the light-emitting device 100.

[0032] The resin material 60 is filled inside the cavity formed by the flat plate portion 11 and the frame portion 13 so as to seal the light-emitting element 20 and cover the side surface of the wavelength converter 40. The resin material 60 is a light-transmitting thermosetting resin such as a silicone resin, for example. In the present Example 1, the case where the resin material 60 is a thermosetting silicone resin will be described.

[0033] Also, inside the resin material 60, as shown in FIG. 2, a plurality of closed spaces 70 are dispersedly formed.

[0034] FIG. 3 is an enlarged cross-sectional view showing a part of the resin material 60 and the plurality of closed spaces 70 of the light-emitting device 100 according to Example 1.

[0035] Each of the plurality of closed spaces 70 preferably has an average diameter of 200 nm or more and 200 μm or less, and more preferably has an average diameter of 200 nm or more and 50 μm or less. If it is less than 200 nm, the intermolecular force is strong and the aggregation of particles is strong. If it exceeds 200 μm, it becomes difficult to control the resin injection. In this embodiment, each of the plurality of closed spaces 70 has, for example, an average diameter of about 200 nm to 300 nm and is formed in a substantially spherical shape. Each closed space 70 contains a resin body 73, and a space in a gaseous state is formed between the resin body 73. Further, the interiors of the plurality of closed spaces 70 contain an organic substance containing a higher alcohol. This organic substance can exist by adhering to the surface of the resin body 73, adhering to the inner wall surface of the closed space 70 of the resin material 60, and the like. Further, the higher alcohol contained inside the plurality of closed spaces 70 is an organic substance that vaporizes at a temperature lower than the thermosetting temperature of the resin material 60. Specifically, the higher alcohol contained inside the plurality of closed spaces 70 preferably vaporizes at a heating temperature at which the viscosity of the silicone resin used as the resin material 60 decreases. In other words, the plurality of closed spaces 70 contain an organic substance inside. Further, the organic substance contained inside the plurality of closed spaces 70 is a higher alcohol. Further, the organic substance contained inside the plurality of closed spaces 70 is an organic substance that vaporizes at a temperature lower than the thermosetting temperature of the resin material 60. Further, each of the plurality of closed spaces 70 has, for example, an average value of the diameter of 200 nm to 300 nm.

[0036] Further, inside each of the plurality of closed spaces 70, a resin body 73 having an outer shape smaller than the shape of each closed space 70 is present. The resin body 73 is, for example, a silicone resin formed in a substantially spherical shape. In other words, the light-emitting device 100 includes a resin material 60 disposed around the light-emitting element 20 and the wavelength converter 40. Further, the resin material 60 has a plurality of closed spaces 70 that each hold a resin body 73. Further, the resin body 73 is a silicone resin.

[0037] The resin material 60 and the plurality of closed spaces 70 function as a light reflector that reflects the light emitted from the light-emitting element 20 and the light emitted from the wavelength converter 40.

[0038] Note that the plurality of closed spaces 70 are formed during the heat curing of the resin material 60 in the manufacturing method described later. Specifically, they are mixed so that the resin bodies 73 are dispersed in the uncured resin which is a precursor of the resin material 60. At this time, the resin bodies 73 are covered with a dispersion medium containing a higher alcohol. Then, during the heat curing of the precursor of the resin material 60, the higher alcohol contained in the dispersion medium vaporizes at a temperature lower than the temperature at which the precursor of the resin material 60 cures. The vaporized higher alcohol expands the resin material 60 around the resin bodies 73, forming the closed spaces 70 around the resin bodies 73. Further, the precursor of the resin material 60 is further heated and cured while the closed spaces 70 are formed, so that the closed spaces 70 remain inside the resin material 60 after heat curing.

[0039] Note that the higher alcohol contained in the dispersion medium is preferably an organic substance that is insoluble in the resin material 60 or the precursor of the resin material 60. Specifically, the dispersion medium is preferably an organic substance in which functional groups such as alkyl groups or hydroxyl groups possessed by the dispersion medium are oriented in both the resin material 60 and the silicone resin which is the resin body 73.

[0040] For example, when both the resin material 60 and the resin body 73 have hydrophobic properties, the dispersion material preferably has a composition containing a lower alcohol and a higher alcohol. Thereby, between the resin body 73 and the precursor of the resin material 60, the alkyl group of the higher alcohol is oriented on the surface of each of the resin body 73 and the precursor of the resin material 60 via the lower alcohol in the dispersion material. Specifically, the dispersion material is, in order from the side of the resin body 73, a higher alcohol with an alkyl group oriented toward the resin body 73 and a hydroxyl group oriented outward, a lower alcohol oriented toward the hydroxyl group of the higher alcohol, and a higher alcohol with a hydroxyl group oriented toward the lower alcohol and an alkyl group oriented toward the precursor of the resin material 60. That is, the dispersion material can form a film-like dispersion material layered in the order of higher alcohol, lower alcohol, and higher alcohol, and it becomes possible to suppress the dissolution into the precursor of the resin material 60. Also, even in the case of the vaporized higher alcohol, since the alkyl group is oriented on the surface of the resin body 73 and the precursor of the resin material 60, the dissolution of the gaseous higher alcohol into the precursor of the resin material 60 is suppressed, and it becomes possible to suppress the variation in diameter due to the shrinkage of the closed space 70 or the like.

[0041] Also, for example, when both the resin material 60 and the resin body 73 have hydrophilic properties, the dispersion material preferably has a composition containing a low molecular weight hydrocarbon and a higher alcohol. Also in this case, between the resin body 73 and the precursor of the resin material 60, each hydroxyl group of the higher alcohol is oriented on the surface of each of the resin body 73 and the precursor of the resin material 60 via the low molecular weight hydrocarbon in the dispersion material. Therefore, similar to the case where both the resin material 60 and the resin body 73 have hydrophobic properties as described above, the dispersion material can form a film-like dispersion material layered in the order of higher alcohol, low molecular weight hydrocarbon, and higher alcohol.

[0042] Note that for the reasons described above, it is preferable that the resin material 60 and the resin body 73 are both made of resin materials having the same polarity of hydrophobicity or hydrophilicity.

[0043] Hereinafter, the functions of the resin material 60 and the plurality of closed spaces 70 as light reflectors will be described.

[0044] As described above, the resin material 60 is a thermosetting silicone resin. That is, the resin material 60 has a refractive index n of about 1.4 to 1.55. Also, as described above, the interior of each of the plurality of closed spaces 70 is in a gaseous state. That is, the interior of each of the plurality of closed spaces 70 has a refractive index n of about 1.0. That is, each of the plurality of closed spaces 70 has a refractive index smaller than that of the resin material 60.

[0045] For example, as shown in FIG. 3, the radiation light LM1 that enters the resin material 60 from the light-emitting element 20 or the wavelength converter 40 and is incident on the interface of each of the plurality of closed spaces 70 from the resin material 60 at a low angle is totally reflected due to the refractive index difference between the resin material 60 and the plurality of closed spaces 70. The totally reflected radiation light LM1 is returned in the direction of the wavelength converter 40 again.

[0046] Also, the radiation light LM2 that enters the resin material 60 from the light-emitting element 20 or the wavelength converter 40 and is incident on the interface of each of the plurality of closed spaces 70 from the resin material 60 at a high angle is scattered by the plurality of closed spaces 70.

[0047] Specifically, as described above, the light-emitting element 20 is a blue LED that emits blue light from a nitride semiconductor. That is, the light-emitting element 20 is a light-emitting element that emits blue light with a wavelength λ of about 460 to 500 nm. Also, the wavelength converter 40 is a wavelength converter containing a phosphor of YAG:Ce. That is, the wavelength converter 40 absorbs the light emitted from the light-emitting element 20 and tends to emit light with a wavelength λ of about 500 to 700 nm. Also, each of the plurality of closed spaces 70 has, for example, an average diameter of about 200 nm to 300 nm. That is, the radiation light LM2 is Mie-scattered by the plurality of closed spaces 70, and the scattered light is returned in the direction of the wavelength converter 40 again.

[0048] Therefore, the resin material 60 and the plurality of closed spaces 70 function as a light reflector due to total reflection at the interface between the resin material 60 and each of the plurality of closed spaces 70 and Mie scattering by the plurality of closed spaces 70, as described above.

[0049] Thus, in the first embodiment, it is possible to select the resin material 60 having a plurality of closed spaces 70 as a light reflector that does not use reflective particles such as titanium oxide inside the resin. Thereby, it is possible to suppress deterioration such as yellowing, cracking, and resin reduction due to depolymerization of the resin material 60 when the light-emitting device 100 is driven for a long time.

[0050] Further, in the first embodiment, it is possible to select the resin material 60 having a plurality of closed spaces 70 as a light reflector that does not use reflective particles such as metal particles inside the resin. Thereby, it is possible to suppress a decrease in the elastic modulus of the resin material 60 after heat curing, and it is possible to suppress the occurrence of cracking of the resin material 60 and peeling between the substrate 10, the light-emitting element 20, or the wavelength converter 40.

[0051] Therefore, the light-emitting device 100 can suppress deterioration of the light-reflective resin material and improve long-term reliability.

[0052] Next, an example of the manufacturing procedure of the light-emitting device 100 will be described with reference to FIGS. 4 to 6.

[0053] FIG. 4 is a diagram showing a manufacturing flow of the light-emitting device 100 according to the first embodiment of the present invention. FIGS. 5 and 6 are enlarged views of the resin body 73 in the resin material 60 in the manufacturing procedure shown in FIG. 4.

[0054] First, as shown in FIGS. 1 and 2, the light-emitting element 20 is bonded to the substrate 10 (step S11: element bonding step). In this step, a substrate 10 having a cavity composed of a flat plate portion 11 and a frame portion 13 and on which the first wiring 15 and the second wiring 17 are formed is prepared. Further, AuSn paste is applied onto the upper surface of the first internal wiring 15I using a dispenser filled with AuSn paste. Further, the light-emitting element 20 is placed on the upper surface of the first internal wiring 15I such that a cathode electrode (not shown) provided on the lower surface of the light-emitting element 20 is in contact with the AuSn paste.

[0055] The substrate 10 in this state is heated to 300°C in, for example, a nitrogen atmosphere to melt the AuSn alloy particles in the AuSn paste and then cooled. As a result, the light-emitting element 20 and the first internal wiring 15I are fixed. Also, the light-emitting element 20 and the first internal wiring 15I are eutectically bonded by the AuSn alloy and electrically connected.

[0056] Note that the position and orientation at which the light-emitting element 20 is fixed are self-aligned by the surface tension of the molten AuSn alloy. Specifically, between the heated and molten AuSn alloy and the light-emitting element 20, the light-emitting element 20 is self-aligned by the surface tension at which the interfacial energy of the molten AuSn alloy is minimized.

[0057] Note that the bonding of the light-emitting element 20 is not limited to this, and a conductive adhesive using an AuSn bump, an AuSn sheet, or an AuSn vapor deposition layer previously formed on the lower surface of each element that does not contain flux may be used. Also, a conductive adhesive such as silver paste or solder may be used.

[0058] Next, as shown in FIGS. 1 and 2, a bonding wire BW is bonded so as to connect the electrode pad 25 of the light-emitting element 20 and the second internal wiring 17I (step S12: wire bonding process). In this step, the substrate 10 to which the light-emitting element 20 is bonded is set in a wire bonding apparatus, and a bonding wire BW such as an Au wire is bonded across the electrode pad 25 of the light-emitting element 20 and the second internal wiring 17I. As a result, the anode electrode of the light-emitting element 20 and the second wiring 17 are electrically connected via the bonding wire BW.

[0059] Next, as shown in FIGS. 1 and 2, a wavelength converter 40 is bonded via an adhesive layer 50 onto the semiconductor layer of the light-emitting element 20 (step S13: wavelength converter bonding step). In this step, the paste serving as the raw material of the adhesive layer 50 is applied onto the semiconductor layer of the light-emitting element 20 using a dispenser filled with the paste. Thereafter, the wavelength converter 40 is placed onto the semiconductor layer such that the paste and the lower surface of the wavelength converter 40 are in contact with each other. Note that the wavelength converter 40 is placed in alignment so as to cover the semiconductor layer. The substrate 10 in this state is heated to cure the raw material of the adhesive layer 50, thereby bonding the light-emitting element 20 and the wavelength converter 40.

[0060] Next, a dispersion step of dispersing the resin body 73 in a precursor 60M of the resin material 60 is performed (step S14: dispersion step). In other words, the method for manufacturing the light-emitting device 100 includes a dispersion step of dispersing the resin body 73 having a dispersion medium containing a higher alcohol in the precursor 60M of the resin material 60 made of a translucent thermosetting resin.

[0061] In this step, first, a resin body 73 covered with a dispersion medium, which is a film containing a higher alcohol that vaporizes at a temperature lower than the heat-curing temperature of the precursor 60M, as a raw material resin of the resin material 60 made of a thermosetting silicone resin, is prepared. The precursor 60M and the resin body 73 covered with the dispersion medium are mixed using, for example, a kneader to disperse the resin body 73 covered with the dispersion medium in the precursor 60M. Note that the order of this step is not limited to this, and it may be performed before step S13 or may be performed in parallel.

[0062] Next, as shown in FIG. 2, a resin material placement step of filling the precursor 60M in which the resin body 73 covered with the dispersion medium is dispersed into the cavity of the substrate 10 is performed (step S15: resin filling step). In this step, the precursor 60M is injected into the cavity formed by the flat portion 11 and the frame portion 13 using a dispenser filled with the precursor 60M, and is filled so as to cover the side surfaces of the light-emitting element 20 and the wavelength converter 40. In other words, the method for manufacturing the light-emitting device 100 includes a resin material placement step of disposing the precursor 60M of the resin material 60 around the light-emitting element 20 on the substrate 10.

[0063] Next, a heat treatment step is performed in which the substrate 10 filled with the precursor 60M in the cavity is heated to thermoset the precursor 60M to form the resin material 60 and to form a plurality of closed spaces 70 (step S16: resin curing step). In other words, the method for manufacturing the light-emitting device 100 includes a heat treatment step of thermosetting the precursor 60M of the resin material 60 and vaporizing the higher alcohol contained in the dispersion material 73D to form the closed spaces 70 in the resin material 60.

[0064] A method for forming a plurality of closed spaces 70 in the resin material 60 will be described in detail with reference to FIGS. 5 and 6.

[0065] FIG. 5 is an enlarged cross-sectional view of the resin body 73 when the precursor 60M in step S15 is filled in the cavity of the substrate 10. FIG. 6 is an enlarged cross-sectional view of the resin body 73 during the thermosetting of the precursor 60M in step S16.

[0066] As shown in FIG. 5, when the resin body 73 is dispersed in the precursor 60M of the resin material 60, the resin body 73 is covered with the dispersion material 73D containing the higher alcohol. In step S15, the precursor 60M in this state is filled in the cavity of the substrate 10.

[0067] Next, in step S16, the resin material 60, the resin body 73, and the dispersion material 73D are heated. As described above, the higher alcohol contained in the dispersion material 73D vaporizes at a temperature lower than the thermosetting temperature of the precursor 60M. As a result, as shown in FIG. 6, the higher alcohol contained in the dispersion material 73D vaporizes, and the precursor 60M is spread by the pressure increased during the vaporization, and a plurality of closed spaces 70, which are spaces containing the higher alcohol in a gaseous state, are formed. Further, the precursor 60M in which the plurality of closed spaces 70 are formed is further heated and thermoset in this state, and becomes the resin material 60 while the plurality of closed spaces 70 are formed.

[0068] Note that the dispersion medium 73D may partially return to a liquid state after the process of step S16, that is, when the resin material 60 is cooled, and may remain inside each of the plurality of closed spaces 70.

[0069] By processing the above steps S11 to S16, the light-emitting device 100 is manufactured.

[0070] According to the first embodiment, by dispersing the resin body 73 covered with the dispersion medium 73D containing a higher alcohol in the precursor 60M of the resin material 60 and heating the same, it is possible to form a light reflector made of the resin material 60 having a plurality of closed spaces 70.

[0071] Thus, in the first embodiment, it is possible to select the resin material 60 having a plurality of closed spaces 70 as a light reflector that does not use reflective particles such as titanium oxide having a photocatalytic effect inside the resin. Thereby, it is possible to suppress deterioration such as yellowing, cracking, and resin reduction due to depolymerization of the resin material 60 when the light-emitting device 100 is driven for a long time.

[0072] Further, in the first embodiment, it is possible to select the resin material 60 having a plurality of closed spaces 70 as a light reflector that does not use reflective particles such as metal particles inside the resin. Thereby, it is possible to suppress a decrease in the elastic modulus after heat curing of the resin material 60, and it is possible to suppress the occurrence of cracking of the resin material 60 and peeling from the support or the like.

[0073] Therefore, the light-emitting device 100 can suppress deterioration of the light-reflective resin material and improve long-term reliability.

Embodiment

[0074] In the first embodiment, the case where a plurality of closed spaces 70 are formed by vaporizing the higher alcohol contained in the dispersion medium of the resin body 73 has been described. However, the method for forming the plurality of closed spaces 70 is not limited to this.

[0075] FIG. 7 is an enlarged cross-sectional view showing a part of the resin material 60 and the plurality of closed spaces 80 of the light-emitting device 100A according to Example 2.

[0076] The light-emitting device 100A has basically the same configuration as the light-emitting device 100 of Example 1. The light-emitting device 100A is different from the light-emitting device 100 in that the resin body 83 existing in the plurality of closed spaces 80 is made of thermally expandable particles. In other words, the resin body 83 is thermally expandable particles.

[0077] A plurality of closed spaces 80 are dispersedly formed inside the resin material 60. Further, inside each of the plurality of closed spaces 80, a resin body 83 having an outer shape smaller than the diameter of each of the closed spaces 80 is present.

[0078] The resin body 83 is made of, for example, a thermally expandable microcapsule composed of a core material 83C containing a low molecular weight hydrocarbon having a boiling point lower than the temperature at which the precursor 60M of the resin material 60 thermosets and a resin body as a shell material covering the core material 83C. Further, inside each of the respective closed spaces 80 and inside each of the resin bodies 83, there are contained organic substances such as gaseous low molecular weight hydrocarbons which are the core material 83C vaporized when the precursor 60M is thermoset. That is, the resin body 83 is a shell material of a hollow thermally expandable microcapsule.

[0079] The core material 83C contains, for example, low molecular weight hydrocarbons having a boiling point lower than the temperature at which the precursor 60M of the resin material 60 such as n-pentane and isopentane thermosets. The resin body 83 is a shell material made of an acrylonitrile-methacrylonitrile copolymer formed so as to cover the core material 83C.

[0080] When the thermally expandable microcapsules are heated, for example, the low-molecular-weight hydrocarbon contained in the core material 83C vaporizes. When the low-molecular-weight hydrocarbon vaporizes, the internal pressure of the resin body 83 increases. By further heating, the acrylonitrile-methacrylonitrile copolymer of the resin body 83 softens, and the resin body 83 expands in a balloon shape. Thereafter, the gaseous low-molecular-weight hydrocarbon in the resin body 83 permeates through the expanded and thinned resin body 83 and is released to the outside of the resin body 83. The resin body 83 shrinks as the low-molecular-weight hydrocarbon is released.

[0081] Hereinafter, with reference to FIGS. 8 to 10, a method of forming each closed space 80 using the thermally expandable microcapsules will be described following the description of the manufacturing method shown in FIG. 4. Note that the manufacturing method of the light-emitting device 100A is basically the same as that of the light-emitting device 100 of Example 1.

[0082] FIG. 8 is an enlarged cross-sectional view of the thermally expandable microcapsules in the dispersion step of step S14 and the filling step of step S15. FIGS. 9 and 10 are enlarged cross-sectional views of the thermally expandable microcapsules during the heat curing of the precursor 60M in step S16.

[0083] In the dispersion step of step S14, the thermally expandable microcapsules are dispersed in the precursor 60M of the resin material 60 (step S14: dispersion step). In other words, the manufacturing method of the light-emitting device 100A includes a dispersion step of dispersing the thermally expandable microcapsules as thermally expandable particles in the precursor 60M of the resin material 60 made of a light-transmitting thermosetting resin.

[0084] Next, in step S15, the precursor 60M in which the thermally expandable microcapsules are dispersed is filled into the cavity of the substrate 10 (step S15: filling step).

[0085] As shown in FIG. 8, when the thermally expandable microcapsules in step S14 are dispersed in the precursor 60M of the resin material 60, the resin body 83 of the thermally expandable microcapsules contains a core material 83C made of a liquid low-molecular-weight hydrocarbon therein.

[0086] Next, a heat treatment step is performed in which the substrate 10 filled with the precursor 60M in the cavity is heated to thermally cure the precursor 60M to form the resin material 60 and to form a plurality of closed spaces 80 (step S16: resin curing step). In other words, the method for manufacturing the light-emitting device 100A includes a heat treatment step of thermally curing the precursor 60M of the resin material 60 and expanding the thermally expandable microcapsules as the thermally expandable particles to form a plurality of closed spaces 80 in the resin material 60.

[0087] In this step, the resin material 60, the resin body 83, and the core material 83C are heated. As described above, the low molecular weight hydrocarbon contained in the core material 83C vaporizes at a temperature lower than the thermal curing temperature of the precursor 60M. As a result, as shown in FIG. 9, the low molecular weight hydrocarbon contained in the core material 83C vaporizes, and the resin body 83 expands due to the pressure increased when it vaporizes, and the precursor 60M is pushed and spread. Thereafter, the vaporized core material 83C passes through the resin body 83 whose thickness has become thinner due to expansion, and the resin body 83 contracts. That is, as shown in FIG. 10, each of the closed spaces 80 is formed inside the precursor 60M. Each of the interiors of the respective closed spaces 80 includes the shrunk resin body 83 and the core material 83C in a gaseous state. Further, the precursor 60M in which each of the closed spaces 80 is formed is further heated in this state and thermally cured to become the resin material 60 while each of the closed spaces 80 is formed.

[0088] Note that the core material 83C may return to a partially liquid state after the treatment in step S16, that is, when the resin material 60 is cooled, and remain inside each of the closed spaces 80 and the resin body 83.

[0089] According to the second embodiment, by dispersing the thermally expandable microcapsules in the precursor 60M of the resin material 60 and heating the same, it becomes possible to form a light reflector made of the resin material 60 having a plurality of closed spaces 80.

[0090] Thus, in the second embodiment, it is possible to select the resin material 60 having a plurality of closed spaces 80 as a light reflector that does not use reflective particles such as titanium oxide inside the resin. Thereby, it is possible to suppress deterioration such as yellowing, cracking, and resin reduction due to depolymerization of the resin material 60 when the light-emitting device 100A is driven for a long time.

[0091] Also, in the second embodiment, it is possible to select the resin material 60 having a plurality of closed spaces 80 as a light reflector that does not use reflective particles such as metal particles inside the resin. Thereby, it is possible to suppress a decrease in the elastic modulus of the resin material 60 after heat curing, and it is possible to suppress the occurrence of cracking of the resin material 60 and peeling between the substrate 10, the light-emitting element 20, or the wavelength converter 40.

[0092] Therefore, the light-emitting device 100A can suppress deterioration of the light-reflective resin material and improve long-term reliability.

[0093] In this embodiment, the case of using thermally expandable microcapsules as an example of the thermally expandable particles has been described. However, the thermally expandable particles that form the closed space 80 are not limited to thermally expandable microcapsules, and any thermally expandable particles that expand and then contract to form the closed space 80 may be used. For example, thermally expandable particles that expand at a temperature lower than the thermosetting temperature of the precursor 60M and contract during cooling after the thermosetting of the precursor 60M may be used. In that case, in the manufacturing method of the light-emitting device 100A, the thermally expandable particles contract during cooling after the completion of the resin curing step in step S16, and the closed space 80 is formed. Also, in that case, the inside of the closed space 80 may be in a depressurized gaseous state. Even if the inside of the closed space 80 is in a depressurized gaseous state, since the refractive index n of the inside of the closed space 80 is about 1.0, the function as a light reflector is the same as in the first and second embodiments.

[0094] In Examples 1 and 2, the case where the light-emitting device 100 has the adhesive layer 50 and the wavelength converter 40 provided on the light-emitting element 20 was described. However, in the present invention, the wavelength converter 40 and the adhesive layer 50 can be provided arbitrarily. For example, in the case of using the light emitted from the light-emitting element 20 without wavelength conversion, the wavelength converter 40 and the adhesive layer 50 may not be provided in the light-emitting device 100.

[0095] Also, in Examples 1 and 2, the case where the resin material 60 is arranged so as to cover the side surface of the light-emitting element 20 was described. However, in the light-emitting device 100 of the present invention, the resin material 60 is not limited to the position in contact with the side surface of the light-emitting element 20 or the lateral position, and may be provided at any position around the light-emitting element 20 where the light emitted by the light-emitting element 20 is received. That is, the resin material 60 may be appropriately provided at a desired position in the light-emitting device 100 to reflect the light emitted by the light-emitting element 20. For example, the resin material 60 may be arranged so as to cover a part of the side surface and the upper surface of the light-emitting element 20 to constitute a side-emitting type light-emitting device 100.

[0096] Also, in the light-emitting device 100 of the present invention, the resin material 60 is not limited to being arranged in close contact with the light-emitting element 20. For example, the resin material 60 can also be arranged around (outside) the light-emitting element 20 covered with another light-transmitting sealing material.

[0097] [Application Example] The resin material 60 having a plurality of closed spaces 70 shown in Example 1 and the resin material 60 having a closed space 80 shown in Example 2 are not limited to the light reflectors of the light-emitting devices 100 and 100A, and can also be applied as light reflection materials in other fields.

[0098] FIG. 11 is a diagram showing a cross-sectional view of a vehicle lamp 200 which is an example of an irradiation device using the same material as that used for the resin material 60 as a light reflection material.

[0099] The vehicle lamp 200 as an irradiation device includes a light source unit 300, a light guide 400, and a reflector 500.

[0100] The light source unit 300 is a light source unit including a light emitting device such as an LED, for example. The light source units 300 are linearly arranged, for example, in the X direction in the figure. Further, in this application example, the light source unit 300 is a light source unit that emits light in the downward direction (-Z direction).

[0101] The light guide 400 is made of a light transmissive resin material such as acrylic, for example, and is a light guide that guides the light emitted from the light source unit 300. The light guide 400 has, for example, an incident surface 410 on which the light emitted from the light source unit 300 enters the inside of the light guide 400 and an exit surface 420 that emits the light entering the inside of the light guide 400. Further, the light guide 400 has, for example, a substantially L-shaped cross-sectional shape, and a light reflecting surface 430 is formed at the bent portion of the substantially L shape. The light emitted from the light source unit 300 enters the inside of the light guide 400 from the incident surface 410 of the light guide 400, is totally reflected by the light reflecting surface 430, and is guided in the direction of the exit surface 420. Further, the light guided in the direction of the exit surface 420 is emitted from the exit surface 420 of the light guide 400 to the outside (-Y direction) of the vehicle lamp 200 as the main orientation LL1 of the vehicle lamp 200.

[0102] Further, the light guide 400 has a diffusing reflecting surface 440 in a region between the light reflecting surface 430 and the exit surface 420. A part of the light totally reflected by the light reflecting surface 430 enters the diffusing reflecting surface 440 and is diffusely reflected, and is emitted from a diffused light exit surface 450, which is the lower surface of the light guide 400, in the direction of the reflector 500.

[0103] The reflector 500 is a light reflector including a support 510 and a light reflecting material 520. In this application example, the same material as the resin material 60 having the closed space used in the first and second embodiments is used for the light reflecting material 520 of the reflector 500.

[0104] The support body 510 is made of a material such as resin, and has a concave surface of a radiation surface type, an elliptical surface type, or a spherical surface type on the surface facing the diffused light emission surface 450 of the light guide body 400. Further, a thermosetting silicone resin and a light reflecting material 520 formed by dispersing a plurality of closed spaces in the silicone resin are applied on the concave surface of the support body 510.

[0105] The light reflecting material 520 is the light reflecting material composed of the resin material 60, the plurality of closed spaces 70, and the resin body 73 shown in Example 1 and the light reflecting material composed of the resin material 60, the plurality of closed spaces 80, and the resin body 83 shown in Example 2. In other words, the light reflecting material 520 is composed of the resin material 60 which is a translucent thermosetting resin having a plurality of closed spaces 70 or 80 each holding a resin body 73 or 83.

[0106] The light emitted from the diffused light emission surface 450 of the light guide body 400 is reflected by the light reflecting material 520 applied to the concave surface of the support body 510 in a direction parallel to the main orientation LL1, and is emitted as the sub - orientation LL2 to the outside (-Y direction) of the vehicle lamp 200.

[0107] Thereby, the vehicle lamp 200 can emit light including the main orientation LL1 and the sub - orientation LL2 in a desired direction.

[0108] Note that the formation method of the light reflecting material 520 is the same as the methods described in Examples 1 and 2. Specifically, a precursor 60M of the resin material 60 in which thermally expandable microcapsules composed of a resin body 73 covered with a dispersion medium 73D containing a higher alcohol or a resin body 83 containing a core material 83C made of a liquid low - molecular - weight hydrocarbon are dispersed is applied to the support body 510 using a method such as spray coating. Then, by heating the support body 510 in this state, the precursor 60M is thermoset and a plurality of closed spaces 70 or a plurality of closed spaces 80 are formed.

[0109] The light reflection materials composed of the resin material 60, the plurality of closed spaces 70, and the resin body 73 shown in Example 1 and the light reflection materials composed of the resin material 60, the plurality of closed spaces 80, and the resin body 83 shown in Example 2 are each applicable as a light reflection material for vehicle lamps.

[0110] Generally, the light reflection material used for the reflector of vehicle lamps is, for example, a metal vapor deposition film in which silver (Ag) or aluminum (Al) or the like is vapor deposited on the support 510. By using a light reflection material composed of a resin material and a plurality of closed spaces as in this application example, it becomes possible to reduce the manufacturing cost of vehicle lamps.

[0111] In addition, by using a light reflection material composed of a resin material, a plurality of closed spaces, and a resin body for the light reflection material of the reflector 500, it is possible to suppress deterioration such as yellowing, cracking, and resin reduction due to depolymerization of the resin material when the vehicle lamp 200 is driven for a long time. In addition, it is also possible to suppress deterioration such as yellowing, cracking, and resin reduction due to depolymerization of the support 510 made of the same resin material. Further, it is possible to suppress a decrease in the elastic modulus of the resin material of the light reflection material after heat curing, and it is possible to suppress the occurrence of cracking of the resin material and peeling from the support or the like.

[0112] Therefore, the light reflection material 520 can suppress the deterioration of the light-reflective resin material and improve the long-term reliability of the vehicle lamp 200 as an irradiation device.

[0113] Note that each of the light reflection materials composed of the resin material 60, the plurality of closed spaces 70, and the resin body 73 shown in Example 1 and the light reflection materials composed of the resin material 60, the plurality of closed spaces 80, and the resin body 83 shown in Example 2 is not limited to the application of vehicle lamps, and can be further applied as a light reflection material in other fields. Specifically, a thermosetting resin can be used for the resin body of the light reflection material, and it is applicable in any field that requires light reflection.

Explanation of Reference Numerals

[0114] 100 Light emitting device 10 Substrate 11 Flat plate part 13 Frame part 15 First wiring 17 Second wiring 20 Light emitting element 25 Electrode pad 30 Element bonding layer 40 Wavelength converter 50 Adhesive layer 60 Resin material 70, 80 Closed space 73, 83 Resin body 200 Vehicle lamp 300 Light source part 400 Light guide 410 Incident surface 420 Exit surface 430 Light reflecting surface 440 Diffuse reflecting surface 500 Reflector 510 Support 520 Light reflecting material

Claims

1. A substrate, a light-emitting element disposed on the substrate, and a resin material made of a translucent thermosetting resin disposed around the light-emitting element, characterized in that the resin material has a plurality of closed spaces each holding a resin body, a light-emitting device.

2. The light-emitting device according to claim 1, wherein the plurality of closed spaces contain an organic substance inside.

3. The light-emitting device according to claim 2, wherein the organic substance is a higher alcohol.

4. The light-emitting device according to claim 2 or 3, wherein the organic substance is an organic substance that vaporizes at a temperature lower than the thermosetting temperature of the resin material.

5. The light-emitting device according to any one of claims 1 to 4, wherein the resin body is a silicone resin.

6. The light-emitting device according to claim 1 or 2, wherein the resin body is a thermally expandable particle.

7. The light-emitting device according to any one of claims 1 to 6, wherein each of the plurality of closed spaces has an average diameter value of 200 nm to 300 nm.

8. A method for manufacturing a light-emitting device including a substrate, a light-emitting element disposed on the substrate, and a wavelength converter disposed on the upper surface of the light-emitting element, comprising: a dispersion step of dispersing a resin body having a film containing a higher alcohol in a resin material made of a translucent thermosetting resin; a resin material placement step of placing the resin material around the light-emitting element on the substrate; and a heat treatment step of heat-curing the resin material and vaporizing the higher alcohol to form closed spaces in the resin material.

9. A method for manufacturing a light-emitting device including a substrate and a light-emitting element disposed on the substrate, comprising: a dispersion step of dispersing thermally expandable particles in a resin material made of a translucent thermosetting resin; a resin material placement step of placing the resin material around the light-emitting element on the substrate; and a heat treatment step of heat-curing the resin material and expanding the thermally expandable particles to form closed spaces in the resin material.

Images