JP6255872B2 - Light emitting device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a light emitting device including a light emitting element and a package, and a manufacturing method thereof.

  Conventionally, light emitting devices have been widely used as light sources for backlights for liquid crystal televisions, lighting fixtures, optical communication devices, and the like. The light-emitting device includes a light-emitting element and a package having a recess that accommodates the light-emitting element (see, for example, Patent Document 1).

JP 2010-153624 A

  By the way, in order to improve the durability of the light emitting device, it is considered effective to cover the surface of the member of the light emitting device with a coating film.

  However, when the inner peripheral surface of the package containing the resin is covered with the coating film, a substance generated by decomposition of the resin material by light and heat tends to stay inside the package, and thus the package may be discolored. In addition, when the supply of oxygen to the inside of the package is blocked by the coating film, the package may be temporarily discolored due to the progress of decomposition of the constituent materials of the package.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a light emitting device capable of suppressing discoloration of a package while improving the durability of the light emitting device, and a method for manufacturing the same.

  The method for manufacturing a light emitting device according to the present invention includes a step of preparing a package including a base material including a resin on which a light emitting element is mounted, and a surface of the package by a coating film having translucency and insulation. A step of covering, and a step of partially providing a highly breathable portion on the coating film. The light emitting device according to the present invention includes a light emitting element, a resin package on which the light emitting element is mounted, and a coating film that covers at least the surface of the resin package and has translucency and insulation, The coating film has a portion having high air permeability and a portion having low air permeability on the surface of the resin package.

  ADVANTAGE OF THE INVENTION According to this invention, the light-emitting device which can suppress the discoloration of a package, improving the durability of a package, and its manufacturing method can be provided.

1 is a schematic plan view of a light emitting device according to an embodiment of the present invention. It is a schematic sectional drawing of the package, coating film, and removal part concerning one Embodiment of this invention. It is a schematic sectional drawing of the package, coating film, and thin part concerning one Embodiment of this invention. It is a schematic sectional drawing explaining the manufacturing method of the light-emitting device concerning one Embodiment of this invention. It is the schematic of the part with high air permeability of the coating film in connection with one Embodiment of this invention, and is a figure which shows the example of the shape of a removal part or a thin part.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic, and the ratio of each dimension may be different from the actual one. Accordingly, specific dimensions and the like should be determined in consideration of the following description.

  The configuration of the light emitting device 100 will be described with reference to the drawings. FIG. 1 is a schematic plan view showing the configuration of the light emitting device 100. FIG. 2 is a schematic cross-sectional view taken along the line AA of FIG.

  The light emitting device 100 of this embodiment mainly includes a light emitting element 10, a package 20, a pair of leads 30, a coating film 40, and a sealing member 50.

Light emitting element 10
The light emitting element 10 is mounted on a light emitting device. The light emitting element 10 is preferably accommodated in a recess 22C in which the package 20 forms at least a part thereof. For example, the light emitting element 10 can be placed on the bottom surface of the recess 22C, and can be placed on the bottom surface of the recess 22C (for example, on the lead 30) as shown in FIG. The light emitting element 10 is fixed to the lead 30 with an adhesive. The light emitting element 10 is electrically connected to the lead 30 via the first wire 10a and the second wire 10b.

  The light emitting element 10 includes a semiconductor layer that emits light in a part thereof. As the light emitting element 10, for example, a blue or ultraviolet light emitting LED formed of a nitride semiconductor represented by a general formula of AlXGaYInZN can be used. Note that 0 ≦ X ≦ 1, 0 ≦ Y ≦ 1, 0 ≦ Z ≦ 1, and X + Y + Z = 1.

  Such a light emitting element 10 can be formed, for example, by epitaxially growing a nitride semiconductor such as InN, AlN, InGaN, AlGaN, InGaAlN on a substrate by a vapor phase growth method such as MOCVD.

  The light emitting element 10 may be made of a semiconductor such as ZnO, ZnS, ZnSe, SiC, GaP, GaAlAs, and AlInGaP in addition to the nitride semiconductor. Such a semiconductor may have a stacked structure in which an n-type semiconductor layer, a light emitting layer (active layer), and a p-type semiconductor layer are sequentially formed. For the light emitting layer, it is preferable to use a laminated semiconductor having a multiple quantum well structure or a single quantum well structure or a laminated semiconductor having a double hetero structure. Note that when a light-transmitting substrate such as a sapphire substrate is used, light is more easily emitted from the light emitting layer toward the side than when a light-impermeable substrate is used, and thus the influence on the package 20 is increased.

  The peak wavelength of the emitted light from the light emitting element 10 can be selected from ultraviolet light to infrared light depending on the semiconductor material and its mixed crystal (composition ratio). The peak wavelength of the emitted light can be 350 nm to 800 nm, preferably 360 nm to 520 nm, and more preferably 420 nm to 480 nm (that is, the short wavelength region of visible light). In addition, since the energy of emitted light increases as the wavelength of emitted light is shorter, the influence on the package 20 becomes stronger.

  In the light emitting element 10, positive and negative electrodes may be formed on the same surface side, or an n-side electrode and a p-side electrode may be formed on opposite sides of the semiconductor, respectively. The light emitting element 10 uses a light emitting element in which at least one electrode is provided on the upper surface, face-up mounting in which the lower surface side opposite to the upper surface is mounted, and positive and negative electrodes are provided on the same surface side, and the surface is mounted Any of flip chip mounting may be used.

Package 20
The light emitting device 100 has, for example, a recess 22C for housing the light emitting element 10. The package 20 forms at least a part of the light emitting device 100, and preferably forms at least a part of the inner peripheral surface 22S of the recess 22C. The recess 22 </ b> C includes at least a base portion 21 and a side wall portion 22. In the present embodiment, the package 20 forms the side surface of the light emitting device 100 and the substantially entire inner peripheral surface of the recess 22C. The base portion 21 and the side wall portion 22 of the recess 22 </ b> C are integrally formed as a package 20.

  The light emitted from the light emitting element 10 is reflected from the inner peripheral surface 22S of the recess 22C, and is emitted from the recess 22C to the outside. The recess 22C is formed in a substantially quadrangular pyramid shape and gradually expands toward the opening side of the recess 22C. As a result, the light emitted from the light emitting element 10 is efficiently emitted to the outside of the light emitting device 100. However, the inner peripheral surface 22S may be substantially perpendicular to the bottom surface of the recess 22C.

  In a direction parallel to the bottom surface of the recess 22C, the distance DT between the light emitting element 10 and the side wall portion 22 (that is, the inner peripheral surface 22S) can be 0.05 mm to 2 mm. When the distance DT is 0.5 mm or less, the influence of the light emitted from the light emitting element 10 on the side wall portion 22 is increased, and the side wall portion 22 is easily decomposed by heat and light. When the inner peripheral surface 22S is substantially perpendicular to the bottom surface of the concave portion 22C, the distance DT between the light emitting element 10 and the inner peripheral surface 22S tends to be small, so that the emitted light from the light emitting element 10 enters the side wall portion 22. The effect will be particularly large.

  In the present embodiment, the outer shape of the package 20 is a substantially rectangular parallelepiped shape, but is not limited thereto, and may be a cylinder, a triangular prism, a polygonal prism of five or more prisms, or a shape similar to these. The package 20 can be formed by mixing the following base material and materials such as particles and then molding by an injection molding method or a transfer molding method.

  In the present embodiment, the package 20 includes a base material composed of a resin and an optionally contained filler, and a plurality of particles mixed with the base material.

  As the resin for the substrate, any kind of resin may be used, but a thermosetting resin is suitable. As the thermosetting resin, an epoxy resin, a triazine derivative epoxy resin, a modified epoxy resin, a silicone resin, a modified silicone resin, or the like can be used. The resin content with respect to the package 20 can be, for example, 10 wt% to 30 wt%.

  Epoxy resins have high mechanical strength and are suitably used as a support for a light-emitting device, but have a problem that discoloration is likely to occur due to light. Therefore, when using an epoxy resin as a base material of a package, the effect of the present invention can be obtained satisfactorily.

  The filler of the base material may include a light reflecting member, an inorganic filler, a curing catalyst, a diffusing agent, a pigment, a fluorescent material, a reflective material, a light shielding material, a light stabilizer, a release agent, and the like. The filler according to the present embodiment includes titanium dioxide as a light reflecting member and silicon dioxide as an inorganic filler. The content rate of titanium dioxide with respect to the whole package 20 can be 10 wt%-30 wt%, for example. The content rate of silicon dioxide with respect to the whole package 20 can be 50 wt%-80 wt%, for example.

Lead 30
Like this embodiment, the light-emitting device 100 may have the lead 30, and the lead 30 may be arrange | positioned at the bottom face of the recessed part 22C. The lead 30 usually has a first lead part 31 and a second lead part 32.

  The first lead portion 31 and the second lead portion 32 are a pair of positive and negative electrodes for electrically connecting the external electrode and the light emitting element 10. As shown in FIG. 1, the first lead portion 31 and the second lead portion 32 are arranged on the bottom surface of the recess 22 </ b> C, and each extend in a different direction. The first lead portion 31 and the second lead portion 32 are exposed on the bottom surface side of the light emitting device 100. Note that the first lead portion 31 and the second lead portion 32 may protrude outward from the side surface of the package 20. In this case, the light emitting device 100 may be folded back to the bottom surface side, or may protrude straight from the side surface of the light emitting device 100.

  The lead 30 is formed using a good electrical conductor such as iron, phosphor bronze, or copper alloy, for example. It is preferable that a plating layer for increasing the reflectance of the emitted light of the light emitting element 10 is formed on the surface of the lead 30. The plated layer can be made of a material containing silver, aluminum, copper, gold, and the like, and preferably contains silver having a high reflectance. The plating layer may be formed by plating only the exposed surface 30S exposed in the recess 22C of the lead 30, or by plating the entire surface of the lead frame before singulation. Also good.

Coating film 40
The coating film 40 covers at least a part of the part formed by the package 20, and preferably covers a part of the inner peripheral surface 22S of the recess 22C. In the present embodiment, the entire inner peripheral surface 22S of the recess 22C, the upper surface 22T of the side wall portion 22, the exposed surface 30S of the lead 30, and the surface of the light emitting element 10 are covered. The thickness of the coating film 40 can be 3 nm to 100 nm.

  The coating film 40 is a film that is denser and less breathable than the package 20 and is made of a light-transmitting material. Examples of such a material include materials mainly composed of aluminum oxide, silicon dioxide, titanium dioxide, zinc oxide and the like. In the present embodiment, “having translucency” means that the absorptance of the emitted light of the light emitting element 10 is 50% or less, and particularly preferably 20% or less. Moreover, it is preferable that the coating film 40 is insulating.

  The coating film 40 can be formed by a conventionally known thin film forming method. Examples of the thin film forming method include a CVD (Chemical Vapor Deposition) method and a sputtering method. In particular, when it is desired to improve the denseness of the coating film 40, the ALD method (Atomic Layer Deposition method) is preferable among the CVD methods.

  The covering film 40 functions as a protective film that protects the inner peripheral surface 22S of the recess 22C formed by the package 20, particularly the side wall part 22, and improves the durability of the side wall part 22. Further, when the surface of the lead 30 is a silver plating layer, the coating film 40 can also function as a sulfidation suppressing film that suppresses sulfidation of the lead 30 and enhances the durability of the light emitting device. However, when the coating film 40 is densely formed by the ALD method or thickly formed by the CVD method, silver sulfidation can be effectively suppressed, but the gas permeability is lowered. Therefore, when the package 20 is decomposed by light emitted from the light emitting element 10 or heat, decomposition products and oxygen are difficult to pass through the coating film 40, and thus the effect of the present invention is high.

  2 and 3 are schematic cross-sectional views schematically showing cross sections of the package 20 and the coating film 40 according to an embodiment of the present invention. FIG. 4 is a schematic cross-sectional view illustrating a method for manufacturing the light emitting device 100 according to an embodiment of the present invention. FIG. 5 is a schematic view of a highly breathable portion of the coating film 40 according to an embodiment of the present invention, and shows an example of the shape of the removal portion 40a or the thin portion 40b.

The covering film 40 is formed with at least a part having high air permeability.
In the embodiment shown in FIGS. 2 and 3, the coating film 40 covering the inner peripheral surface 22S of the recess 22C is removed or thinned, and has a portion having higher air permeability than other portions. . As a result, when the package, in particular, the side wall portion of the inner peripheral surface 22S of the recess 22C is decomposed by the light or heat of the emitted light, the decomposition product is removed from the removal portion 40a or the thin portion 40b of the coating film 40 into the package 20. Can be efficiently discharged to the outside. As a result, it can suppress that the package 20 discolors with a decomposition product. Furthermore, since oxygen can be supplied to the package 20 through the removal part 40a or the thin part 40b of the coating film 40, decomposition of the constituent material caused by an oxygen deficient state can also be suppressed.

  In order to increase the air permeability of the coating film 40, the coating film 40 is partially removed or thinned after the film formation. Specifically, the entire coating film 40 is removed or thinned, or is removed sparsely or thinned. The method for forming such a highly breathable part is not particularly limited, for example, making a hole in the film with a jig such as a needle, disassembling and removing the film by laser irradiation, dissolving the film with a solvent, The film can be removed by pressing, etching the film with plasma, or the like.

  The air permeability can be easily adjusted by changing the conditions of each method of removal or thinning. The air permeability can be increased by increasing the area and number of the removal portions 40a and the thin portions 40b and reducing the thickness of the thin portions 40b. In particular, when a needle or a laser is used, the removal portion 40a and the thin portion 40b can be partially formed without using a mask or the like, which is excellent in mass productivity. Further, the number and size of the holes can be easily adjusted, which is preferable.

  The area of the removed portion 40a or the thin portion 40b of the coating film 40 is preferably 1.5% to 100% of the area of the side wall portion 22, for example. When the coating film 40 protects the package 20, it is preferable that the coating film 40 is removed sparsely or thinned. In the case of protecting other members, for example, the lead 30, all of the coating film 40 provided to cover the package 20 may be removed. When the coating film 40 is loosely (partially) removed or thinned, it can be easily manufactured by using a jig such as a needle or a laser, which is preferable.

  When part of the coating film 40 on the side wall part is removed or thinned, it is preferable to provide a plurality of the removing part 40a or the thin part 40b according to the area of the side wall part. The plurality of removed portions 40a or thin portions 40b are preferably dispersed uniformly. Thereby, discoloration of the package 20 can be favorably prevented. For example, in the case of a method of removing a film with a needle or a laser, a hole removal portion 40a having a diameter of about 5 mm is provided so that the distance between the removal portions 40a is as equal as possible (uniform). Is desirable.

  Further, the shape of the removing portion 40a or the thin portion 40b in plan view is not particularly limited, and is not limited to the substantially circular shape as shown in FIG. 5A, but is an ellipse or as shown in FIG. It may be a square, a linear shape as shown in FIG. Further, when the film is removed by laser irradiation, the excimer laser is irradiated several times in the vertical and horizontal directions to form a lattice-like (net-like) removal portion 40a or thin portion 40b as shown in FIG. You can make it.

  Further, in the side wall portion 22 of the recess, the portion close to the light emitting element 10 tends to cause discoloration of the package 20. For this reason, it is preferable that the removal part 40a or the thin part 40b of the coating film 40 is provided only in a part close to the light emitting element in the side wall part 22 of the concave part or more than the other part. As a result, the package 20 can be protected while preventing discoloration of the package 20.

Sealing member 50
In the present embodiment, the sealing member 50 is filled in the recess 22 </ b> C and seals the light emitting element 10. Although the material of the sealing member 50 is not specifically limited, It is preferable to use resin excellent in translucency, heat resistance, weather resistance, and light resistance. Examples of such a resin include the various thermosetting resins described above.

  The sealing member 50 may contain a known additive such as a filler, a diffusing agent, a pigment, a fluorescent material, and a reflective material. As the diffusing agent, for example, barium titanate, titanium oxide, aluminum oxide, silicon oxide and the like are suitable. By providing such a diffusing agent, the light emitted from the light emitting element is diffused, so that discoloration of the package can be reduced.

  Further, the sealing member 50 may contain a fluorescent material that absorbs light emitted from the light emitting element 10 and converts the wavelength. Examples of the fluorescent material include nitride-based phosphors mainly activated by lanthanoid elements such as Eu and Ce, oxynitride-based phosphors, sialon-based phosphors, lanthanoid-based substances such as Eu, and transition metals such as Mn. Alkaline earth halogen apatite phosphors, alkaline earth metal borate phosphors, alkaline earth metal aluminate phosphors, alkaline earth silicates, alkaline earth sulfides mainly activated by elements of the system Mainly activated by lanthanoid elements such as alkaline earth thiogallate, alkaline earth silicon nitride, germanate, Ce and other lanthanoid elements such as rare earth aluminate, rare earth silicate, Eu Organic and organic complexes. By providing such a fluorescent material, the wavelength of at least a part of the light emitted from the light emitting element can be increased, and the energy of the light emitted from the light emitting element can be weakened. Can be reduced.

  A part of such a sealing member 50 may be provided so as to enter the removal portion 40a, or may be provided so as to close the opening of the removal portion 40a.

  A method for manufacturing the light emitting device 100 will be described with reference to FIGS. 4 and 2. FIG. 4 is a schematic cross-sectional view for explaining the method for manufacturing the light emitting device 100.

  First, as shown in FIG. 4A, the lead 30 is set in a mold, and the material of the package 20 is poured and hardened to form the package 20 and the lead 30 integrally. At this time, a recess 22 </ b> C for accommodating the light emitting element 10 is formed in the package 20. Further, the lead 30 is exposed on the bottom surface of the recess 22C.

  Next, as shown in FIG. 4B, the light emitting element 10 is mechanically connected to the lead 30 by an adhesive. Then, the light emitting element 10 is electrically connected to the lead 30 by the first wire 10a and the second wire 10b.

  Next, as shown in FIG. 4C, the inner peripheral surface 22S of the concave portion 22C, the upper surface 22T of the side wall portion 22, the exposed surface 30S of the lead 30, and the surface of the light emitting element 10 are formed using a thin film forming method. Are covered with a coating film 40. Specifically, a method for forming an aluminum oxide film using the ALD method will be described. First, H2O gas is introduced into the chamber, and OH groups are formed on the surface of the object to be coated (in this embodiment, the side wall portion 22, the lead 30, and the light emitting element 10). Next, after exhausting the surplus gas, TMA (trimethylaluminum) gas is introduced into the chamber, and an object to be coated with the coating film 40 (in this embodiment, the side wall portion 22, the lead 30 and the light emitting element 10) Next, OH groups on the surface react with TMA (first reaction) Next, H 2 O gas is introduced into the chamber to react TMA and H 2 O bonded to OH groups (second reaction). Then, the first reaction and the second reaction are repeated to form a dense aluminum oxide film having a desired thickness.

  Next, a plurality of holes are made in the coating film covering the side wall portion of the package, for example, with a needle, and, for example, as shown in FIG. 2, a portion having good air permeability (that is, the removal portion 40a) is formed. .

  Next, the sealing member 50 is filled in the recess 22C, and the sealing member 50 is heated to be cured.

  Thus, the light emitting device 100 is completed.

  Although the present invention has been described according to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the above embodiment, one light emitting element 10 is accommodated in the recess 22C, but the present invention is not limited to this. A plurality of light emitting elements 10 may be accommodated in the recess 22C. In this case, all the light emitting elements 10 may be the same type, and the light emission peak wavelength may be different for each light emitting element 10. Therefore, for example, three light emitting elements that exhibit red, green, and blue light emission colors can be accommodated in the recess 22C.

  In the above-described embodiment, the coating film 40 includes the inner peripheral surface 22S of the recess 22C and the upper surface 22T of the side wall 22 formed on the entire surface of the package 20, the exposed surface 30S of the lead 30, and the surface of the light emitting element 10. However, it is only necessary to cover at least a part of the inner peripheral surface 22S of the recess 22C. Even in this case, it is possible to protect the package 20 and suppress discoloration.

  In the above embodiment, the portion having good air permeability is provided by making a hole with a needle so that decomposition products and oxygen can pass through the coating film 40, but the present invention is not limited to this. The method of forming a part with good air permeability in the coating film is a method of removing or thinning all or a part of the film to be prevented from discoloration by physical or chemical method after the coating film is formed. Anything to do. For example, a portion having good air permeability is formed by making a hole in the film with a needle-like tool, removing the film by laser irradiation, or thinning the film by etching with a solvent or plasma. When etching is used, it is preferable to mask a portion other than the portion where the removed portion or the thin portion is desired to be formed with a resist or the like.

As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 10 ... Light emitting element 10a ... Wire 10b ... Wire 20 ... Package 21 ... Base part 22 ... Side wall part 22C ... Concave part 22S ... Inner peripheral surface 22T ... Upper surface 30 ... Lead 30S ... exposed surface 31 ... lead 32 ... lead 40 ... covering film 40a ... removal part 40b ... thin part 50 ... sealing member 100 ... light emitting device

Claims (13)

A step of preparing a package that includes a substrate including a resin on which the light emitting element is mounted and has a recess for mounting the light emitting element;
Covering the surface of the package with a coating film having translucency and insulation;
Providing a part of the coating film with a part having high air permeability;
With
The method for manufacturing a light-emitting device, wherein the highly air-permeable portion is provided only in a portion close to the light-emitting element in the side wall portion of the recess, or more than other portions. The method for manufacturing a light-emitting device according to claim 1, wherein the coating film is formed by an atomic layer deposition method. The light emitting device manufacturing method according to claim 1, wherein a lead is provided in the recess, and the coating film covers a surface of the lead. 4. The light emitting device according to claim 1, wherein the step of providing a part with high air permeability in the coating film partially removes or thins the coating film. 5. Device manufacturing method. 5. The light emitting device according to claim 1, wherein the step of providing a part with high air permeability in the coating film is laser irradiation, pressing, or etching. A light emitting element;
A package having a recess in which the light emitting element is mounted, and a substrate including a resin;
A coating film that covers at least the surface of the package and has translucency and insulation;
With
The coating film has a highly breathable part and a low part,
The light-emitting device, wherein the highly air-permeable portion is provided only in a portion close to the light-emitting element in the side wall portion of the recess, or more than other portions. The light emitting device according to claim 6 , wherein the coating film is removed or thinned in the highly breathable portion. The light emitting device according to claim 6 or 7 , wherein the package contains an epoxy resin and a filler. The light emitting device according to claim 8 , wherein the filler includes at least one of silicon dioxide and titanium dioxide. The coating covers the surface of the lead, the light emitting device according to any one of claims 6 to 9. The coating film comprises an aluminum oxide or silicon dioxide as a main component, the light emitting device according to any one of claims 6 to 10. The light emitting device according to any one of claims 6 to 11 , wherein a distance between the light emitting element and the side wall of the recess is 2 mm or less. The peak wavelength of the light emitted from the light emitting element is 360nm or more 520nm or less, the light emitting device according to any one of claims 6 to 12.

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