JP2016066632A - Light emission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emission device that can suppress color unevenness of light emitted outwards while suppressing dispersion of wavelength conversion at a light emission layer.SOLUTION: A light emission device 10 has a light emission element 30 having a light emission face S, a protection element 40 comprising a Zener diode, a sub mount board 20 on which the light emission element 30 and the protection element 40 are mounted, a sheet member 50 coupled to the light emission face S through adhesive agent, and a reflection layer 60 surrounding the light emission element 30 and the sheet member. The sheet member 50 has a fluorescent layer 51 which is excited by light from the light emission element 30 and emits wavelength-converted light, and a diffusion layer 52 containing a diffusion material for diffusing light from the fluorescent layer 51. Since the fluorescent layer 51 and the diffusion layer 52 are constructed by one sheet member 50, the fluorescent layer 51 and the diffusion layer 52 can be simply provided on the light emission face S of the light emission element 30, and light from the fluorescent layer 51 can be diffused by the diffusion layer 52, whereby color unevenness can be suppressed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light emitting device including a fluorescent layer containing a phosphor that is excited by light from a light emitting element and converts the wavelength.

  For example, if the light emitting device that emits white light is a light emitting element that emits blue light, the light emitting device includes a fluorescent layer that contains a phosphor that emits yellow light that is excited by blue light and has a complementary color. For this reason, it is desirable to make the thickness of the fluorescent layer uniform, which affects the degree of wavelength conversion, in order to make the balance due to the color mixture of blue light and yellow light uniform and reduce color unevenness.

  Regarding a technique for making the thickness of the fluorescent layer uniform, it is known that the fluorescent layer is formed by a sheet member (for example, refer to Patent Documents 1 and 2).

  The manufacturing method of the light emitting device of Patent Document 1 includes a first step of placing the light emitting element on the substrate, and a second step of exposing the upper surface of the light emitting element and covering the side surface of the light emitting element with the first light reflective member. After the step and the second step, after the third step, the third step of applying an adhesive on the upper surface and bonding the light-transmitting member containing the phosphor to the light emitting element, and the third step, And a fourth step of exposing the upper surface of the translucent member and covering the side surface of the translucent member with the second light reflective member.

  The light emitting device of Patent Document 2 has an inclined surface in which an outer peripheral side surface of a translucent member containing a phosphor that transmits light emitted from a light emitting element and emits the light to the outside spreads from the upper surface toward the lower surface, The area of the lower surface of the light transmissive member is formed larger than the area of the upper surface of the light emitting element, and the lower surface of the light transmissive member and the upper surface of the light emitting element are joined together by an adhesive. Thus, it is described that a portion not joined to the light emitting element and the inclined surface are covered with a light reflecting resin.

JP 2010-192629 A JP 2010-272847 A

  By forming the phosphor layer containing the phosphor with the sheet member, the thickness of the sheet member can be easily made uniform, so that the wavelength conversion variation due to the phosphor layer can be suppressed.

  However, the light emitting element has high emission intensity in the directly upward direction, and the phosphor that emits light when excited by the light from the light emitting element emits light in all directions. If it shifts to the surroundings, the emission color of the phosphor becomes stronger. Therefore, even if the thickness of the fluorescent layer is made uniform, color unevenness cannot be suppressed.

  Accordingly, an object of the present invention is to provide a light emitting device capable of suppressing color unevenness of light emitted to the outside while suppressing variation in wavelength conversion in a fluorescent layer.

  A light-emitting device of the present invention includes a light-emitting element having a light-emitting surface, a sheet member bonded to the light-emitting surface, and a reflective layer surrounding the light-emitting element and the sheet member, A fluorescent layer containing a phosphor that is excited by light from a light emitting element and emits wavelength-converted light, and a diffusion layer containing a diffusing material that diffuses light from the fluorescent layer To do.

  Since the light emitting device of the present invention includes the fluorescent layer and the diffusion layer as the sheet member, it is possible to suppress unevenness in the color of light emitted to the outside while suppressing variations in wavelength conversion in the fluorescent layer.

Sectional drawing which shows the light-emitting device which concerns on embodiment of this invention FIG. 1 is a plan view of the light emitting device shown in FIG. 1 is a circuit diagram for explaining a connection between a light emitting element and a protective element of the light emitting device shown in FIG. (A)-(D) are sectional drawings for demonstrating each process of the manufacturing method of the light-emitting device shown in FIG. The partially expanded view for demonstrating shrinkage | contraction with the diffused layer and reflective layer of the sheet | seat member of the light-emitting device shown in FIG.

  1st invention of this application is equipped with the light emitting element which has a light emitting surface, the sheet | seat member joined to the light emitting surface, and the reflective layer surrounding the light emitting element and the sheet | seat member, and a sheet | seat member is from a light emitting element. A light-emitting device comprising: a fluorescent layer containing a phosphor that emits light that is excited by light and wavelength-converted; and a diffusion layer that contains a diffusion material that diffuses light from the fluorescent layer .

  According to the first invention, since the fluorescent layer is formed in a sheet shape as a part of the sheet member, the thickness of the fluorescent layer can be made uniform, so the level of wavelength conversion by the phosphor is made uniform. Variation can be suppressed. In addition, since the diffusion layer is provided in the fluorescent layer, the light from the light emitting element that has passed through the fluorescent layer is diffused. Therefore, the fluorescent material contained in the fluorescent layer has a good balance with the yellow light emitted in all directions. Since the colors can be mixed, it is possible to obtain white with reduced color unevenness.

  A second invention of the present application is the light emitting device according to the first invention, wherein the linear expansion coefficient of the diffusion layer is larger than that of the fluorescent layer.

  According to the second invention, even when the reflective layer contracts due to temperature change, the diffusion layer whose linear expansion coefficient is larger than the fluorescent layer contracts greatly, pulling the reflective layer and preventing the reflective layer from cracking. To do.

  A third invention of the present application is the light-emitting device according to the first or second invention, wherein the height of the diffusion layer and the reflection layer is adjusted by cutting.

  According to the third invention, by cutting and aligning the height positions of the diffusion layer and the reflection layer, the reflection layer becomes lower than the diffusion layer, light leaks from the side surface of the diffusion layer, or the reflection layer becomes the diffusion layer. It is possible to prevent the emission of light from being covered and being blocked.

  A fourth invention of the present application is the light emitting device according to any one of the first to third inventions, wherein the sheet member is formed larger than the light emitting surface of the light emitting element.

  According to the fourth aspect of the invention, since the sheet member is larger than the light emitting surface of the light emitting element, it is possible to secure a wide area of light emission by the fluorescent layer, so that a high luminance light emitting device can be obtained.

  A fifth invention of the present application is the light emitting device according to any one of the first to fourth inventions, wherein the light emitting surface of the light emitting element is formed in an uneven surface.

  According to the fifth aspect of the invention, it is possible to reduce the return light that is totally reflected on the light emitting surface of the light emitting element and returns to the light emitting element, so that the light extraction efficiency of the light emitting element can be improved. Therefore, the light emission intensity directly above the light emitting element can be increased, and even the light emitting element with the light emission intensity directly above can suppress color unevenness by the diffusion layer.

(Embodiment)
A light emitting device according to an embodiment of the present invention will be described with reference to the drawings.

  The light emitting device 10 shown in FIGS. 1 and 2 includes a submount substrate 20, a light emitting element 30, a protective element 40, a sheet member 50, and a reflective layer 60.

  The submount substrate 20 is a substrate in which a wiring pattern (not shown) is formed on the insulating substrate 21. The light emitting element 30 and the protective element 40 are mounted on the element electrode formed by the wiring pattern formed on the mounting surface of the submount substrate 20, and the element electrode is formed on the bottom surface of the insulating substrate 21. The connection electrode is connected via a through-hole electrode. As the insulating substrate 21, for example, glass epoxy resin, BT resin (bismaleimide triazine resin-based thermosetting resin), ceramics, or the like can be used.

  The light emitting element 30 is a flip chip type light emitting diode, and the outline of the light emitting surface S is formed in a square shape. The light emitting element 30 is conductively mounted on the element electrode formed on the mounting surface of the submount substrate 20 via the bumps B.

  The light emitting element 30 includes a substrate, a semiconductor layer, an n-side terminal, and a p-side terminal. The substrate plays a role of holding the semiconductor layer, and a surface opposite to the surface on which the semiconductor layers are stacked is a light emitting surface S from which light is emitted. As the material of the substrate, insulating sapphire, GaN, SiC, AlGaN, AlN, or the like can be used. The light emitting surface S of the substrate has a microtexture structure by making it a rough surface with minute irregularities by etching, blasting, processing with a laser or a dicing blade, or the like. When the substrate is sapphire or the like and the substrate having a lower refractive index than GaN is used as a base material, the substrate may be formed with a flat surface.

  The semiconductor layer is obtained by sequentially stacking an n-type layer, a light emitting layer, and a p-type layer on a substrate. The material of these semiconductor layers is preferably a gallium nitride compound. Specifically, the n-type layer is GaN, the light-emitting layer is InGaN, the p-type layer is GaN, and the like. As the n-type layer and the p-type layer, Al-based, In-based, Ga-based, and N-based layers can also be used. It is also possible to form a buffer layer made of GaN or InGaN between the n-type layer and the substrate. Further, for example, the light emitting layer may have a multilayer structure (quantum well structure) in which InGaN and GaN are alternately stacked.

  The n-side terminal is formed by removing the light-emitting layer and the p-type layer from a part of the n-type layer, the light-emitting layer, and the p-type layer laminated on the substrate, exposing the n-type layer, and on the exposed n-type layer. Is formed. The p-side terminal is formed on the p-type layer. The p-side terminal is a terminal formed of Ag, Al, Rh or the like having high reflectivity in order to reflect the light emitted from the light emitting layer to the substrate side.

  The flip-chip type has been described in detail as the light-emitting element 30, but a double-sided electrode type FD (Face Down) type and FU (Face Up) in which electrodes are respectively formed so as to sandwich the substrate and the semiconductor layer. ) Type light emitting element.

  The protection element 40 is for preventing an excessive voltage from being applied to the light emitting element 30. In the present embodiment, a Zener diode is connected to the light emitting element 30 as the protection element 40. A circuit diagram in a state where the light emitting element 30 is connected to the protective element 40 is shown in FIG. In the first embodiment, the protective element 40 is the Zener diode ZD, but it may be a diode, a varistor, a capacitor, a resistor, or the like.

  The sheet member 50 is affixed to the light emitting surface S, which is the substrate of the light emitting element 30, and the fluorescent layer 51 in which the adhesive surface on the light emitting element 30 side is the light incident surface, and the surface exposed from the light emitting device 10 is the light emitting surface. The light transmissive member is formed in a two-layer structure with the diffusion layer 52. The fluorescent layer 51 and the diffusion layer 52 are each formed in a sheet shape, and are bonded together in the manufacturing process by laminating one layer on the other layer. The sheet member 50 is formed larger than the light emitting surface S of the light emitting element 30.

  The fluorescent layer 51 contains a phosphor that converts a wavelength to light that is excited by light from the light emitting element 30 and becomes complementary color in a transparent medium that is a main material such as resin or glass or ceramics. For example, if the light emitting element 30 is a blue light emitting element that emits blue light, the phosphor may emit yellow light. By including the phosphor that emits yellow light in the phosphor layer 51, the blue light from the light emitting element 30 and the yellow light from the phosphor are mixed, so that white light can be obtained. As the phosphor, a silicate phosphor or a YAG phosphor can be used.

  As the transparent medium, for example, a resin mainly composed of a silicone resin, an epoxy resin, and a fluororesin, or a glass material produced by a sol-gel method can be used. Some glass materials have a curing reaction temperature of about 200 degrees Celsius, and can be said to be a suitable material in consideration of heat resistance of materials used for bumps and terminals.

  The diffusion layer 52 contains a diffusion material that diffuses light from the fluorescent layer 51 in a transparent medium mainly composed of resin. The diffusing material can be, for example, particulate silicon dioxide or ceramics. The transparent medium can be a silicone resin, glass, acrylic resin, or the like.

  As the adhesive for bonding the fluorescent layer 51 and the diffusion layer 52 together and bonding them, those made of silicone resin can be used. If the diffusion layer 52 is formed of a silicone resin and the adhesive is a silicone resin, refraction and reflection upon incidence on the diffusion layer 52 can be reduced.

  The reflective layer 60 is an area on the submount substrate 20 on which the light emitting element 30 is mounted, and surrounds the periphery of the light emitting element 30 and the sheet member 50 in the remaining area of the mounting area of the light emitting element 30. The sheet member 50 is formed so as to cover the protection element 40 and is exposed to the sheet member 50 bonded to the light emitting surface S of the light emitting element 30.

  The reflective layer 60 is a granular reflective material that reflects light from the light emitting element 30 in a transparent medium such as epoxy resin, acrylic resin, polyimide resin, urea resin, silicone resin, fluororesin, or a main material such as glass. Are dispersed.

  The reflective layer 60 can be formed by curing a liquid resin containing titanium oxide or zinc oxide particles and a dispersant as a reflective material that reflects light. By forming the reflective layer 60 by curing a liquid resin containing powdered titanium oxide and a dispersant, the reflective layer 60 can be provided with a reflective function while maintaining insulation. In addition, when the reflective layer 60 is formed, a thixotropic agent may be added to the liquid resin for the purpose of improving fluidity. As the thixotropy-imparting agent, for example, fine powder silica can be used.

  In Embodiment 1, titanium oxide is used as the reflective material, but zinc oxide, aluminum oxide, silicon dioxide, boron nitride, or the like can also be used as the reflective material. That is, the reflective material can be used as long as it is a metal oxide having an insulating property and a reflective function.

  A method of manufacturing the light emitting device according to the embodiment of the present invention configured as described above will be described with reference to the drawings.

  First, the light emitting element 30 and the protection element 40 are mounted on the submount substrate 20 via the bumps B (see FIG. 4A).

  Next, an adhesive is applied to the light emitting surface S of the light emitting element 30, and the sheet member 50 formed to have a size larger than the light emitting surface S of the light emitting element 30 is attached (see FIG. 4B). Since the fluorescent layer 51 and the diffusion layer 52 form one sheet member 50, the fluorescent layer 51 and the diffusion layer 52 can be easily provided on the light emitting surface S of the light emitting element 30.

  Next, a resin containing a reflective material to be the reflective layer 60 (reflective material-containing resin) is filled and cured by a printing method or a potting method (see FIG. 4C). At this time, the reflecting material-containing resin 61 is filled so that the sheet member 50 is covered.

  Then, until the diffusion layer 52 of the sheet member 50 is exposed, the cured reflective material-containing resin 61 is cut to form the reflection layer 60, and the height positions of the diffusion layer 52 and the reflection layer 60 are matched (FIG. 4). (See (D)).

  Thus, by cutting and matching the height positions of the diffusion layer 52 and the reflection layer 60, the reflection layer 60 becomes lower than the diffusion layer 52, and light leaks from the side surface of the diffusion layer 52. It is possible to prevent the diffusion of the light from being covered by covering the diffusion layer 52.

  Next, a usage state of the light emitting device 10 according to the embodiment of the present invention will be described.

  When power is supplied to the light emitting device 10 shown in FIG. 1, the light emitting element 30 emits light. Since the light emitting surface S of the light emitting element 30 is formed as an uneven surface, it is possible to reduce the return light that is totally reflected by the light emitting surface S and returns to the light emitting element 30. Can be improved. Accordingly, the light emission intensity in the direction directly above the light emitting element 30 can be increased.

  When the blue light from the light emitting element 30 is incident on the fluorescent layer 51, it becomes light that passes through the fluorescent layer 51 and passes through the diffusion layer 52 and light that excites the phosphor.

  Since the fluorescent layer 51 is formed in a sheet shape as a part of the sheet member 50, the thickness of the fluorescent layer 51 can be made uniform, so that the level of wavelength conversion by the fluorescent substance is made uniform and variation is suppressed. be able to.

  Further, even in the light emitting element 30 in which the light emitting surface S has a concavo-convex surface to increase the light emission intensity in the directly upward direction, the diffusion layer 52 is provided on the fluorescent layer 51 so that it passes through the fluorescent layer 51. Since the blue light is diffused, the phosphor contained in the phosphor layer 51 can be mixed with the yellow light emitted in all directions in a well-balanced manner, so that the color can be white with suppressed color unevenness.

  Therefore, the light emitting device 10 can suppress uneven color of light emitted from the diffusion layer 52 to the outside while suppressing variation in wavelength conversion in the fluorescent layer 51.

  Since the diffusion layer 52 is formed in a sheet shape as a part of the sheet member 50, the thickness of the diffusion layer 52 can be made uniform. Therefore, since the degree of diffusion by the diffusion layer 52 can be made uniform as a whole, color unevenness can be further suppressed.

  The light emitted from the light emitting element 30 to the side can be reflected by the reflective layer 60 and directed toward the sheet member 50.

  Since the sheet member 50 is larger than the light emitting surface S of the light emitting element 30, it is possible to secure a wide area of light emission by the fluorescent layer 51. Therefore, the light emitting device 10 with high luminance can be obtained.

  By emitting light, the light emitting element 30 generates heat and the temperature rises. Further, if the current supply to the light emitting element 30 is stopped, the temperature of the light emitting element 30 is lowered. For example, when the transparent medium for forming the fluorescent layer 51 is made of glass or ceramics, and the reflective layer 60 is formed of a resin having a larger linear expansion coefficient than the fluorescent layer 51, such as a silicone resin, the light emitting element 30 repeats light emission. Due to the temperature change caused by this, the reflective layer 60 repeats expansion and contraction. At this time, if the diffusion layer 52 is not present, the reflective layer 60 may be greatly contracted, and cracks may occur in the reflective layer 60 near the interface with the fluorescent layer 51.

  However, in the light emitting device 10, since the diffusion layer 52 having a larger linear expansion coefficient than that of the fluorescent layer 51 is provided in the fluorescent layer 51, the diffusion layer 52 contracts the reflective layer 60 as shown in FIG. By pulling or compressing, a large change due to the contraction of the reflective layer 60 is suppressed, so that the occurrence of cracks in the reflective layer 60 can be prevented.

  In this embodiment, the light emitting element 30 emits blue light and the phosphor emits yellow light that is a complementary color of blue light. However, the light emitting element emits ultraviolet light. Or can emit other colors. In addition, the phosphor may emit other colors.

  Since the present invention can suppress unevenness in color of light emitted to the outside while suppressing variations in wavelength conversion in the fluorescent layer, the fluorescent layer contains a phosphor that is excited by light from the light emitting element and converts the wavelength. It is suitable for a light emitting device provided with

DESCRIPTION OF SYMBOLS 10 Light-emitting device 20 Submount substrate 21 Insulating substrate 30 Light-emitting element 40 Protection element 50 Sheet member 51 Fluorescent layer 52 Diffusion layer 60 Reflective layer 61 Reflective material containing resin B Bump S Light-emitting surface

Claims (5)

A light emitting device having a light emitting surface;
A sheet member joined to the light emitting surface;
A reflective layer surrounding the light emitting element and the sheet member;
The sheet member is excited by light from the light emitting element, and includes a fluorescent layer containing a phosphor that emits wavelength-converted light;
And a diffusion layer containing a diffusion material for diffusing light from the fluorescent layer. The light emitting device according to claim 1, wherein a linear expansion coefficient of the diffusion layer is larger than that of the fluorescent layer. The light-emitting device according to claim 1, wherein the diffusion layer and the reflective layer are aligned in height by cutting. The light emitting device according to claim 1, wherein the sheet member is formed larger than a light emitting surface of the light emitting element. The light emitting device according to claim 1, wherein a light emitting surface of the light emitting element is formed on an uneven surface.

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