JP2008034546A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device improved in light emitting efficiency by employing a sealing member excellent in light resistance and heat resistance so as to cope with the light-emitting element of high brightness. <P>SOLUTION: In the light emitting device having a constitution that light is emitted by impressing a driving current on the light emitting element; the sealing member for sealing the light emitting element is provided with light transparency. The sealing member has an inside layer disposed closer to the emitting layer with higher reflective index than that is an outer layer. The glass transition point of the material of the inside layer is lower than that of the material of the outside layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement of a light emitting device using a light emitting element such as a light emitting diode (hereinafter also referred to as “LED”) or a semiconductor laser (hereinafter also referred to as “LD”).

Light emitting elements such as LEDs and LDs are expected to be used as illumination light sources, and improvement in light extraction efficiency from these light emitting elements is desired. Further, the light emitting element of the light emitting device is generally sealed with a sealing member, and conventionally, the light emitting element has been sealed with a resin-based sealing member such as an epoxy resin or a silicone resin.
However, in recent years, the durability required for sealing members has increased due to an increase in the amount of heat generated by increasing the brightness of the light-emitting element, and the longer wavelength life of the light-emitting element and the life of the light-emitting device. In the case of the system sealing member, it has been difficult to achieve satisfactory performance. When a resin, particularly an epoxy resin, is used as the sealing member, deterioration such as yellowing occurs due to light or heat, so that transparency is lowered and light extraction efficiency is deteriorated. In addition, since the opaque portion has a reduced function due to the above-described deterioration, the function as a sealing member is deteriorated, which causes a problem such as a deterioration of the light emitting element and a shortened life as a light emitting device.

  For this reason, Patent Documents 1 and 2 propose using a low-melting glass as a sealing member in order to improve the life.

Japanese Patent Laid-Open No. 2004-200531 JP 2006-32500 A

  By the way, if it seals with the low melting glass material which shows a low glass transition point (Tg = 300 degreeC-500 degreeC) like patent document 1, 2, it will seal without damaging a light emitting element, a wire bond, etc. it can. However, in the case of a material having a low glass transition point (Tg), there is a problem that the refractive index is low and the light extraction efficiency is poor.

  In view of the above, an object of the present invention is to provide a light-emitting device having good light extraction efficiency by using a sealing member having good light resistance and heat resistance corresponding to a high-luminance light-emitting element.

  According to the first aspect of the present invention, in the light emitting device configured to emit light by applying a driving current to the light emitting element, the light emitting device has a light-transmitting sealing member that covers the light emitting element, and the sealing member Comprises an inner layer disposed closer to the light emitting element and an outer layer disposed outside the inner layer, and the refractive index of the inner layer is higher than the refractive index of the outer layer. And the glass transition point of the inner layer is lower than the glass transition point of the outer layer.

  According to a second invention, in the configuration of the first invention, the inner layer has a refractive index of 1.5 or more and 2.5 or less and a glass transition point (Tg) of 130 ° C. or more and 350 ° C. or less. Features.

  A third invention is characterized in that, in the configuration of the first invention or the second invention, the inner layer is formed of a low melting point glass containing tin fluoride or tin oxide.

  According to a fourth invention, in the structure of the third invention, the outer layer is a low-melting glass containing an aluminum compound.

  According to a fifth invention, in the structure of the fourth invention, a part of the aluminum compound is alumina, and the alumina is contained in an amount of 0.5 wt% to 10 wt%.

  A sixth invention is characterized in that the sealing member is sealed inside a package having a recess, and the surface of the package and the surface of the sealing member are covered with a silicone resin. To do.

  According to the configuration of the present invention, the light extraction efficiency is high, the light emitting element and the like are not damaged, the deliquescence is good, and the light emitting element having high durability has long-term durability. Equipment can be provided.

BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the light emitting device of the present invention will be described with reference to the drawings. However, the present invention is not limited to this, and is modified to the extent that the effects of the present invention can be maintained. But you can.
(First embodiment)
FIG. 1 is a schematic end view of a light emitting device 100 according to the first embodiment. The light emitting device 100 emits light when a driving current is applied to the light emitting element 112. The light emitting element 112 is configured such that an electrode (not shown) of the light emitting element 112 and a terminal 113 are connected by a wire (not shown), and a drive current is applied to emit light. Here, the wire (not shown) is required to have good mechanical connectivity, electrical conductivity, etc. between the light emitting element 112 and the terminal 113, such as gold, silver, copper, platinum, etc. and alloys thereof. Etc. can be used. The terminal 113 also preferably has good mechanical connectivity and electrical conductivity with a wire (not shown) or the like. Since the light emitting element 112 is placed on the tip of the terminal 113, the processability is improved. Good materials are preferable, and specific materials include iron and copper. The light emitting element 112 has a transparent sealing member 114. The sealing member 114 is formed of an inner layer 115 disposed close to the light emitting element 112, an outer layer 116 disposed outside the inner layer 115, and two low-melting glass layers. ing. The inner layer 115 has a refractive index higher than that of the outer layer 116 and is made of low melting glass having a glass transition point lower than that of the outer layer 116.

  Here, the light emitting element 112 is formed on the substrate by, for example, liquid layer growth or metal organic chemical vapor deposition (MOCVD), GaAlN, ZnS, ZnSe, SiC, GaP, GaAlAs, AlN, InN, AlInGaP, InGaN, What formed semiconductors, such as GaN and AlInGaN, as a light emitting layer is used. The semiconductor structure may be a homo structure, a hetero structure, a double hetero structure, or a single quantum well structure or a multiple quantum well structure in order to give a quantum effect. Depending on the material of the semiconductor layer, the emission wavelength can be variously selected from ultraviolet light to infrared light, and the color of the emitted light can be determined. According to the structure of the present invention, since the sealing member 114 that seals the light emitting element 112 uses low-melting glass, the light emitting element 112 is not easily deteriorated by ultraviolet rays. Therefore, the wavelength of the light emitting element 112 is shorter than 400 nm. A light having a main light emission wavelength in a short wavelength region of light can also be used.

  Further, in the light-emitting device 100, a phosphor that can absorb visible light and absorb light from the light-emitting element 112 can be used. It is also possible to emit white light or the like by mixed light of light from the element and the phosphor. Note that the phosphor can be mixed and arranged in the sealing member 114 as described later.

  Here, the low-melting-point glass used as the sealing member 114 has a light-transmitting property so that light from the light-emitting element 112 is transmitted. When the light-emitting element 112 that emits light in the ultraviolet region is used, From the viewpoint of refractive index, melting point, and transmittance, phosphoric acid type is preferable. Among them, from the viewpoint of transparency, ammonia type or sodium type phosphate glass is preferable. Also, aluminum phosphate glass is preferred from the viewpoint of deliquescence. For example, the inner layer 115 of the sealing member 114 is formed by using ammonia phosphate glass (glass transition point Tg: 250 ° C., refractive index: 1.7) as a low melting glass, and the outer layer 116 is made of aluminum. When formed using phosphoric acid-based glass (glass transition point Tg: 400 ° C., refractive index: 1.5 to 1.6), the light emitting element 112 and the wire (not shown) are not damaged, Since the refractive index is lowered toward the outside, the light emitting device has a good light extraction efficiency. Further, since the outer layer 116 is formed of a low-melting glass containing an aluminum compound, it is preferable in that the deliquescence seen in the phosphate-based low-melting glass can be reduced.

The inner layer 115 is preferably a low melting glass having a refractive index of 1.5 to 2.5 and a glass transition point (Tg) of 130 ° C. to 350 ° C. If the low-melting glass of the inner layer 115 has a refractive index of less than 1.5, it is not preferable because the light extraction efficiency from the inner layer 115 to the outer layer 116 decreases, and if the refractive index is larger than 2.5, This is not preferable because the light extraction efficiency from the light emitting element 112 to the inner layer 115 is lowered. Further, it is not preferable that the low melting point glass of the inner layer 115 has a glass transition point (Tg) of less than 130 ° C., because the inner layer 115 melts due to heat generated from the light emitting element during operation. When Tg) is higher than 350 ° C., the light emitting element 112 is exposed to a high temperature when the inner layer 115 is cured and is damaged by heat, which is not preferable. Therefore, by using a low melting point glass having a refractive index of 1.5 or more and 2.5 or less and a glass transition point (Tg) of 130 ° C. or more and 350 ° C. or less in this way, it has excellent reliability and light extraction efficiency. Thus, a light emitting device having a good brightness can be obtained.

  The main component of the inner layer 115 is preferably low-melting glass containing tin fluoride or tin oxide. By adjusting the compounding ratio of the low melting point glass and tin fluoride or tin oxide, the refractive index and the glass transition point (Tg) can be easily adjusted. Therefore, the refractive index of the inner layer 115 can be adjusted to a desired value depending on the light emitting element to be used. Further, when the light emitting element or the like is sealed, the glass transition point (Tg) can be adjusted to a sufficiently low level so as not to damage the light emitting element or the like. By including tin fluoride or tin oxide in this way, tin fluoride or tin oxide can be used to adjust the refractive index and glass transition point (Tg) of low-melting glass and adjust light extraction efficiency. Easy to do.

  Furthermore, it is preferably a low-melting glass in which a part of the aluminum compound contained in the outer layer 116 is alumina. Since the aluminum compound is contained in this manner, the unpaired electron of the phosphorus-oxygen bond oxygen in the phosphate glass and the aluminum ion are combined and stabilized, so that the glass surface is stabilized. The deliquescence on the side in contact with outside air is reduced. Further, when a part of the aluminum compound is alumina, the low melting point glass can be easily adjusted by post-addition or the like, and the handleability can be improved. Alumina also has the effect of increasing the glass transition point (Tg) of the low-melting glass.

  Preferably, the alumina is 0.5 wt% or more and 10 wt% or less. When the addition amount of alumina is less than 0.5 wt%, it is not preferable in terms of high deliquescence, and when the addition amount is more than 10 wt%, the glass transition point (Tg) of the low melting glass is increased. Further, the presence of white spots derived from alumina is conspicuous, and the transparency is lowered. Therefore, it is preferable to add 0.5 wt% or more and 10 wt% or less of alumina, thereby suppressing the glass transition point (Tg) at a certain temperature while suppressing deliquescence and maintaining transparency.

  Further, as described above, the sealing member 114 may contain a phosphor that converts at least a part of the emission wavelength of the light emitting element 112. The phosphor absorbs light from the light emitting element and converts it into light having a different wavelength, and YAG phosphor, nitride phosphor, and other phosphors can be used. For example, nitride phosphors / oxynitride phosphors mainly activated by lanthanoid elements such as Eu and Ce, lanthanoid phosphors such as Eu, and alkalis mainly activated by transition metal elements such as Mn Earth halogen apatite phosphor, alkaline earth metal borate halogen phosphor, alkaline earth metal aluminate phosphor, alkaline earth silicate, alkaline earth sulfide, alkaline earth thiogallate, alkaline earth silicon nitride At least selected from organic and organic complexes mainly activated by lanthanoid elements such as germanate or lanthanoid elements such as Ce, rare earth aluminate, rare earth silicate or Eu Any one or more are preferable. As specific examples, the following phosphors can be used, but are not limited thereto.

(1) A nitride phosphor mainly activated by a lanthanoid element such as Eu or Ce is M ₂ Si ₅ N ₈ : Eu (M is at least one selected from Sr, Ca, Ba, Mg, and Zn). More than seeds). In addition to M ₂ Si ₅ N ₈ : Eu, MSi ₇ N ₁₀ : Eu, M _1.8 Si ₅ O _0.2 N ₈ : Eu, M _0.9 Si ₇ O _0.1 N ₁₀ : Eu (M is Sr, Ca, Ba, And at least one selected from Mg and Zn).

(2) An oxynitride phosphor mainly activated by a lanthanoid element such as Eu or Ce is MSi ₂ O ₂ N ₂ : Eu (M is at least selected from Sr, Ca, Ba, Mg, Zn) 1 type or more).

(3) An alkaline earth halogen apatite phosphor mainly activated by a lanthanoid-based element such as Eu or a transition metal-based element such as Mn is M ₅ (PO ₄ ) ₃ X: R (M is Sr, Ca, At least one selected from Ba, Mg and Zn, X is at least one selected from F, Cl, Br and I. R is Eu, Mn, any one of Eu and Mn Etc.).

(4) Alkaline earth metal borate halogen phosphor is M ₂ B ₅ O ₉ X: R (M is at least one selected from Sr, Ca, Ba, Mg, Zn. X is F , Cl, Br, or I. R is Eu, Mn, or any one of Eu and Mn).

(5) Alkaline earth metal aluminate phosphors are SrAl ₂ O ₄ : R, Sr ₄ Al ₁₄ O ₂₅ : R, CaAl ₂ O ₄ : R, BaMg ₂ Al ₁₆ O ₂₇ : R, BaMg ₂ Al ₁₆ O ₁₂ : R, BaMgAl ₁₀ O ₁₇ : R (R is Eu, Mn, or any one of Eu and Mn).

(6) Alkaline earth sulfide phosphors include La ₂ O ₂ S: Eu, Y ₂ O ₂ S: Eu, and Gd ₂ O ₂ S: Eu.

(7) Rare earth aluminate phosphors mainly activated by lanthanoid elements such as Ce are Y ₃ Al ₅ O ₁₂ : Ce, (Y _0.8 Gd _0.2 ) ₃ Al ₅ O ₁₂ : Ce, Y ₃ (Al _{0.8 Ga 0.2) 5 O 12:} Ce, and the like _{(Y, Gd) 3 (Al} , Ga) YAG -based phosphor represented by the composition formula of ₅ O _12. Further, there are Tb ₃ Al ₅ O ₁₂ : Ce, Lu ₃ Al ₅ O ₁₂ : Ce, etc. in which a part or all of Y is substituted with Tb, Lu, or the like.

(8) Other phosphors are ZnS: Eu, Zn ₂ GeO ₄ : Mn, MGa ₂ S ₄ : Eu (M is at least one selected from Sr, Ca, Ba, Mg, Zn. X Is at least one selected from F, Cl, Br, and I.).

  The phosphor described above contains one or more selected from Tb, Cu, Ag, Au, Cr, Nd, Dy, Co, Ni, Ti instead of Eu or in addition to Eu, as necessary. You can also. Further, phosphors other than the above-described phosphors and having the same performance and effect can be used.

  These phosphors can use phosphors having emission spectra in yellow, red, green, and blue by the excitation light of the light-emitting element, and emission spectra in yellow, blue-green, orange, etc., which are intermediate colors between them. A phosphor having the following can also be used. By using these phosphors in various combinations, light emitting devices having various emission colors can be manufactured.

For example, when a GaN-based compound semiconductor that emits blue light and Y ₃ Al ₅ O ₁₂ : Ce or (Y _0.8 Gd _0.2 ) ₃ Al ₅ O ₁₂ : Ce that absorbs blue light and emits yellow light are combined, It is possible to provide a light-emitting device that emits white light with the mixed color. In addition, a light emitting element that emits ultraviolet light and CaSi ₂ O ₂ N ₂ : Eu or SrSi ₂ O ₂ N ₂ : Eu that absorbs ultraviolet light and emits light from green to yellow emits blue light (Sr, A combination of Ca) ₅ (PO ₄ ) ₃ Cl: Eu and red (Ca, Sr) ₂ Si ₅ N ₈ : Eu can provide a light emitting device that emits white light with good color rendering. . Since the three primary colors of light, red, blue, and green are used, desired white light can be realized only by changing the blending ratio of the first phosphor and the second phosphor.

  According to the light emitting device 100 of the first embodiment, the sealing member 114 of the light emitting device 100 is composed of two or more layers of low-melting glass, and the inner layer 115 of the sealing member 114 is refracted by the outer layer 116. Since it is made of a low melting point glass having a glass transition point (Tg) higher than that of the outer layer 116 and lower than the glass transition point (Tg) of the outer layer 116, the light extraction efficiency is good and the light emitting element is damaged. There is nothing to do. In addition, if at least the outer layer 116 of the sealing member 114 is formed of a low-melting glass containing an aluminum compound, the glass surface is stabilized, so that deliquescence is reduced.

  FIG. 1B is a schematic end view of a light emitting device 110 according to a modification of the first embodiment. The parts denoted by the same reference numerals as those in the first embodiment have a common configuration, and thus description thereof will be omitted, and different points will be mainly described. In the first embodiment, the sealing member 114 is a two low-melting-point glass layer including an inner layer 115 in the vicinity of the light emitting element 112 and an outer layer 116 formed outside the inner layer 115. Although formed, the light emitting device 110 may further include an outer layer 117 as shown in FIG. In that case, the refractive index is adjusted so as to decrease sequentially from the inner layer to the outer layer, and the glass transition point (Tg) is higher toward the outer layer. . If you increase the number of layers and adjust the refractive index stepwise from the inner layer to the outer layer in order to reduce the difference in refractive index between the outer layer and the air, which is the outermost layer, This is more preferable because the light extraction efficiency is improved. In this case, as described above, the outer layer 117 of the outer layer 116 may be configured to include an aluminum compound or include a phosphor as in the outer layer 116. Thus, as described above, it is possible to reduce deliquescence and to convert the light emission color of the light emitting element.

(Second Embodiment)
FIG. 2 shows a light emitting device 200 according to the second embodiment. The portions denoted by the same reference numerals as those in the first embodiment have the same configuration, and thus the description thereof will be omitted. Here, differences from the light emitting device 100 will be mainly described. A difference from the light emitting device 100 is that a devitrified glass layer 217 as a reflective layer is provided in a direction opposite to the light emitting surface 112 a of the light emitting element 112.

Here, the devitrified glass layer 217 is obtained by dispersing a scatterer (not shown) in the low melting point glass to adjust transparency, and light from the light emitting element 112 is opposite to the light emitting surface 112a. This is a layer that can prevent the light extraction efficiency from decreasing in the direction of the side. The scatterer is not particularly limited as long as it can be dispersed in the low-melting glass. For example, SiO ₂ or Al ₂ O ₃ having a particle size in the Fraunhofer scattering region is preferable.

  According to the configuration of the second embodiment, in addition to the effect of the first light emitting device, the devitrified glass layer 217 is formed, so the direction opposite to the light emitting surface from the light emitting element 112 is formed. The light that has passed through is reflected by the devitrified glass layer 217 and scattered to the upper portion 112a, whereby the light extraction efficiency from the upper surface on the top 114a side can be further improved.

(Third embodiment)
FIG. 3 shows a light emitting device 300 according to the third embodiment. The portions denoted by the same reference numerals as those in the first embodiment have the same configuration, and thus the description thereof will be omitted. Here, differences from the light emitting device 100 will be mainly described. The light emitting device 300 is a so-called surface mount type light emitting device. The difference from the light emitting device 100 is that the light emitting element 112 is fixed and electrically connected to the recess bottom surface portion 319b of the package 318 having the recess 319. And this recessed part 319 is filled with low melting glass. The light emitting element 112 fixed to the bottom surface portion 319b of the recess is embedded in the low-melting glass to form an inner layer 315. A sealing member 314 is formed by an inner layer 315 in the vicinity of the light emitting element and an outer layer 316 formed outside the inner layer 315. The materials used in the inner layer 315 and the outer layer 316 and the configurations of the refractive index and the glass transition point (Tg) are the same as those in the first embodiment. Here, the recess bottom surface portion 319b and the light emitting element 112 are fixed using, for example, a conductive paste / eutectic material (AuSn, AgSb, etc.) (not shown) in which a conductive filler such as silver or carbon is dispersed. . Specifically, a pair of wiring conductors (not shown) spaced apart from each other are formed in the recess 319 of the package 318, and one end of the wiring conductor (not shown) is disposed on the bottom surface 319b of the recess. ing. And the wiring conductor (not shown) and the light emitting element 112 are being fixed with the electrically conductive paste (not shown) etc. in this recessed part bottom face part 319b. A wiring conductor (not shown) extends from the concave bottom surface portion 319b of the package 318 to the concave side surface portion 319a and from the top surface side 318a of the package 318 to the side surface 318b, and extends to the back side 318c serving as a mounting surface with the circuit board. ing. In this embodiment mode, the light-emitting element 112 is connected to a wiring conductor (not shown) with a wire (not shown). However, the present invention is not limited to this, and flip-chip mounting using eutectic or the like is also possible. .

  The shape of the outer layer 316 is preferably an R shape having a convex portion on the upper side of the drawing. Although the light extraction efficiency can be improved by using the R shape, the light from the light emitting element 112 may be condensed by using the R shape. Therefore, when it is desired to reduce the concentration of light, a scattering agent (not shown) is added to the outer layer 316 or a layer containing a scattering agent (not shown) so as to further overlap the outer layer 316. ) Can be solved. The scattering agent used here is preferably added to the extent that the light from the light emitting element does not interfere with the light from the light emitting element because it passes through the sealing member and the layer containing the scattering agent to the outside. Other effects of the present embodiment are the same as those of the first embodiment.

  As a material of the package 318, a resin material, a hybrid material such as glass epoxy in which an inorganic substance is contained in an organic substance, or an inorganic material such as a ceramic material can be used. In particular, when high heat resistance and high weather resistance are desired, it is preferable to use a hybrid material or an inorganic material. In addition, when a high-luminance light emitting element is used, a material with high thermal conductivity is preferable in order to efficiently dissipate heat generated from the light emitting element and improve durability. As the high thermal conductive material, for example, a ceramic material is preferable, and among these, aluminum nitride is preferable from the processed surface.

  Here, when a concave package using a ceramic material is used as the package 318 for mounting the light emitting element, the light emitting element 112 fixed in the concave portion 319 of the ceramic material is heated to a certain temperature in advance and then has a low melting point. It is preferable to fill the recess 319 with glass and cool it. Thereby, in the molded product after being filled with the low melting point glass, the glass and the package can be fixed from the difference in the linear expansion coefficient when returning to the temperature, and peeling at these interfaces is reduced.

(Fourth embodiment)
FIG. 4 shows a light emitting device 400 according to the fourth embodiment. The light emitting device 400 is also a so-called surface mount type light emitting device. The portions denoted by the same reference numerals as those in the first embodiment and the third embodiment have a common configuration, and therefore description thereof will be omitted here and different points will be mainly described. The difference from the third embodiment is the shape of the inner layer 415 that is the sealing member 414 in the vicinity of the light emitting element 112. Here, the inner layer 415 also has an R shape. Thus, by making both the inner layer 415 and the outer layer 416 R-shaped, it is possible to further improve the light extraction efficiency compared to the planar shape. Here, the materials used in the inner layer 415 and the outer layer 416, the refractive index, the glass transition point (Tg), and the like are the same as those in the first embodiment and the third embodiment, and other effects are also obtained. It is the same.

(Fifth embodiment)
FIG. 5 shows a light emitting device 500 according to the fifth embodiment. The light emitting device 500 is also a so-called surface mount type light emitting device. The portions denoted by the same reference numerals as those in the first embodiment and the third embodiment have a common configuration, and therefore description thereof will be omitted here and different points will be mainly described. The difference from the third embodiment is that the shape of the inner layer 515 in the vicinity of the light emitting element 112 is provided as an R shape, and the outer layer 516 is provided outside the inner layer 515 to form a sealing member 514. In addition, a silicone resin layer 517 is provided on the outer side of the outer layer 516, and the surfaces of the sealing member 514 and the package 318 are covered with the silicone resin 517.

  Here, in the case where a light emitting element having a main light emission wavelength in the ultraviolet region is used as the light emitting element 112, a phosphor (not shown) is dispersed in the sealing material layer 514 when whitening, and this phosphor is converted. It is preferable to arrange them in order of efficiency. For example, the inner layer 515 is an ammonia phosphate glass (glass transition point Tg: 250 ° C., refractive index: 1.7) in which a phosphor that converts ultraviolet light into red light is dispersed as the first low-melting glass. The outer layer 516 is formed using aluminum-phosphate glass (glass transition point Tg: 400 ° C., refractive index 1.5 to 1.6) as the second low melting point glass. Further, a silicone resin 517 (glass transition point Tg: 100 ° C., refractive index: 1.4 to 1) in which a phosphor that converts ultraviolet light into blue and a phosphor that converts green light is dispersed further outside the outer layer 516. .46). Also in this case, as in the first embodiment described above, the refractive index is adjusted so as to decrease sequentially from the inner layer to the outer layer, and the glass transition point (Tg) is increased from the inner layer to the outer layer. The relationship becomes higher toward the layer, and the effect is the same as that of the modification of the first embodiment. Since it is formed so as to be covered with the silicone resin 517 on the outer side of the outer layer, there is an effect that the water resistance is further improved.

  Although not shown, for example, a sealing member that seals a light emitting element having a main light emission wavelength in the ultraviolet region may be a light emitting device configured as follows. That is, the inner layer disposed closer to the light emitting element is formed using ammonia-based low melting point glass. Next, a phosphor-containing layer is formed on the surface of the inner layer using a low-melting glass in which a phosphor that converts ultraviolet light into red light is dispersed. Then, an outer layer is formed on the outer side of the phosphor-containing layer using an aluminum / phosphoric acid low-melting glass. A silicone resin layer in which a phosphor that converts ultraviolet light into blue and a phosphor that converts green is dispersed is formed on the outer side of the outer layer to form a light emitting device. In this case, the refractive index of each layer is 1.7 for the ammonia-based low melting glass in the inner layer, 1.6 for the low melting glass in which the R phosphor is dispersed, The refractive index of the low melting point glass of aluminum / phosphate is 1.5, and the refractive index of the silicone resin is 1.4 to 1.46. The silicone resin layer has a role of preventing deliquescence of the phosphate glass. Furthermore, although not shown in the above-described embodiment, the package 318, the sealing members 314, 414, and 514 and the boundary portion are sealed with a water-resistant material. In this way, water and air can be prevented from entering through the gap, and the adhesion between the package 318 and the sealing members 314, 414, and 514 is further improved.

  Next, an example of a method for manufacturing the light emitting device 100 according to the first embodiment will be described with reference to FIGS. A step of embedding the light-emitting element 112 in the first low-melting glass 615 heated and melted, and a first low-melting-point glass material 615 in which the light-emitting element 112 is embedded are cooled and solidified in the mold 620 and the inner side The manufacturing method includes a step of forming the layer 115 and a step of integrating the outer layer 116 of the inner layer 115.

FIG. 6A is a diagram showing a first manufacturing process. The terminal 113 and the light emitting element 112 are integrated in advance, fixed to the working mold 619, and heated. The heating temperature is determined in relation to the glass transition point (Tg) of the first low-melting glass to be used. For example, when the glass transition point (Tg) of the first low melting point glass is about 200 ° C., the heating temperature of the working mold 619 is also set to the glass transition point (Tg) of about the first low melting point. Next, the mold 620 was heated to 250 ° C., and the melted first low-melting glass 615 was poured into the bullet-shaped cavity 620 a of the mold 620.
Then, the terminal 113 and the light emitting element 112 fixed to the working mold 619 are injected into the cavity 620a of the mold 620 and embedded in the first low melting point glass 615, while the mold 620 and the working mold are filled. 619 was closed. In this state, it is cooled to about 100 ° C. and solidified while the light emitting element 112 is embedded in the first low melting point glass 615 to form the inner layer 115. At this time, a fixing pin (not shown) for positioning is provided on the mold 620 so that the light emitting element 112 can be easily positioned at the center of the shell mold, and a receiving part (not shown) for the fixing pin is provided on the working mold 619. May be provided. Here, as described above, the first low-melting glass uses a material in which the refractive index and the glass transition point (Tg) are adjusted.

  Next, FIG.6 (b) is a figure which shows a 2nd manufacturing process. The mold 621 has a hollow portion 621 a having an outer shape that is slightly larger than the shape of the inner layer 115. This mold 621 is heated in advance to near the glass transition point (Tg) of the second low melting point glass 616. Then, a melted second low-melting glass 616 is poured into the cavity 621a. Next, the inner layer 115 created in FIG. 6A, the light emitter element 112, and the terminal 113 are integrated into the second low-melting glass 616 of the mold 621, and the mold 621 and The working mold 619 is closed and cooled in this state. At this time, it is preferable to gradually cool at a cooling rate of about 50 ° C./second or less. Since cooling is performed slowly, bubble generation at the interface between the inner layer 115 and the outer layer 116 is suppressed, and scattering caused by bubbles is suppressed. By this step, the outer layer 116 can be integrated with the surface of the inner layer 115.

  FIG. 6C is a schematic end view of the light emitting device 100 obtained in the above-described process. According to the manufacturing process of the light emitting device 100, a highly reliable light emitting device can be manufactured with a high yield.

  In addition, when a layer is provided on the outer side of the outer layer 116, although not shown, it can be provided in the same process as the case where the outer layer 116 is formed using the second low melting point glass described above. That is, a third low melting point glass having a glass transition point (Tg) higher than that of the second low melting point glass is used, and the mold is heated to the glass transition point (Tg) or higher. Next, the molten third low melting point glass is poured into the cavity of the mold. The cavity has an outer shape that is slightly larger than the outer dimension of the outer layer 116. Next, in this third low-melting glass, the inner layer 115 integrated with the outer layer 116 of the second low-melting glass obtained in the above step, the light emitter element 112, and the terminal 113 are put, Fix and cool. Similar to the second low melting point glass solidifying step, the cooling step can be gradually cooled to obtain the same effect. Here, as described above, low-melting glass containing a phosphor may be used for each layer. In this way, when each layer is formed of low-melting glass containing a phosphor, for example, a blue light-emitting element can be used to obtain a white light-emitting device. Further, by providing multiple layers, it is possible to subdivide each layer by putting phosphors of each color in each layer. Further, by providing multiple layers, the refractive index can be gradually changed from the vicinity of the light emitting element toward the outside, so that the light extraction efficiency can be improved.

  Next, an example of a method for manufacturing the light emitting device 400 according to the fourth embodiment will be described with reference to FIGS. In this manufacturing method, the first low-melting glass 715 is preliminarily formed into an arbitrary shape and then placed on the light-emitting element 112 so that the gold is maintained at the glass transition point (Tg) or higher of the first low-melting glass 715. The step of forming the inner layer 415 by forming the surface of the first low-melting glass 715 into an arbitrary shape with the mold 728, and the second low-melting glass 716 disposed outside the inner layer 415 Forming the outer layer 416 and integrating it with the inner layer 415. FIG. 7A shows a process of forming the first low-melting glass 715 using a mold. The mold 725 includes a first mold 723 and a second mold 724. The first mold 723 has an R shape on the top surface of the molded product, and the bottom surface of the molded product is substantially circular. It has a housing part 715b for housing the light emitting element in the center, and is composed of a second mold 724 having a side surface part connected to the outer edge of the circle. A space 725a formed by combining the first mold 723 and the second mold 724 is filled with the first low-melting glass 715 heated and melted, cooled, solidified, and molded.

In FIG. 7B, the light emitting element 112 is fixed in advance to the recess bottom surface portion 319 b of the recess 319 of the package 318, and the first low melting point glass 715 obtained in the above process is placed in the recess 319 of the package 318. It is a process. Here, a wiring conductor (not shown) is formed in the package 318 in advance, and this wiring conductor is provided separately from the bottom surface portion 319b of the recess. And the light emitting element 112 is being fixed to the one end part of the wiring conductor (not shown) arrange | positioned at the recessed part bottom part 319b via the electrically conductive paste (not shown).
The package 318 and the light emitting element 112 are previously heated to about the glass transition point (Tg) of the first low melting point glass 715. Then, the first low-melting glass 715 obtained by the above-described molding is placed in the recess 319 of the package 318. At this time, the light emitting element 112 is accommodated in an accommodating portion 715 b formed on the bottom surface of the molded first low melting point glass 715.

  FIG. 7C illustrates a state in which the first low-melting glass 715 is fixed to the recess 319 of the package 318 and the light-emitting element 112 is accommodated so as to be embedded in the first low-melting glass 715. 1 is a step of adjusting the outer shape of the upper surface 715 a of the low melting point glass 715 and forming the inner layer 415. The third mold 728 is set so as to be equal to or higher than the glass transition point (Tg) of the first low melting point glass 715 while keeping the package 318 and the light emitting element 112 in a heated state. With the heated third mold 728, the upper surface 715a is held in the direction indicated by the arrow in the drawing, the outer shape is adjusted, and the light emitting element 112 accommodated in the accommodating portion 715b is embedded in the first low melting point glass. And the inner layer 415 is formed.

  FIG. 7D is a step of pouring the second low-melting glass 716 into the upper surface 415a of the inner layer 415 obtained in the step of FIG. 7C described above. An appropriate amount of the second low melting point glass 716 is poured into the upper surface 415a of the inner layer 415 in a state where the second low melting point glass 716 is heated to the glass transition point (Tg) or higher and melted. Here, the second low-melting glass 716 may be one in which a phosphor or the like is dispersed. Further, when pouring, the upper surface 415a of the inner layer 415 may be heated to such an extent that its outer shape does not collapse.

  FIG. 7E shows a step of forming the outer layer 416 with the second low melting point glass 716 poured into the upper surface 415 a of the inner layer 415. The fourth mold 729 is set to be equal to or higher than the glass transition point (Tg) of the second low melting point glass 716. The fourth mold 729 and the outer shape covering the upper surface 415a of the inner layer 415 are formed to have an outer shape. The second low melting point glass 716 is fixed while being suppressed by the fourth mold 729. In this state, the second low-melting glass material 716 is gradually cooled to solidify, and after solidification, the fourth mold 729 is removed to form the outer layer 416. The formed outer layer 416 is formed so as to cover the upper surface 415a of the inner layer 415. Therefore, even if the inner layer 415 has poor deliquescence, the light emitting device can sufficiently withstand actual use. 400.

  Since the light-emitting device 400 obtained in the above-described process is molded into an arbitrary shape in advance using the first low-melting glass, positioning is easy when embedding the light-emitting element, and the space between the light-emitting element and the light-emitting element is obtained. The area where the low melting point glass layer does not enter is reduced. That is, since an air layer is not interposed and bubbles are not generated, a light emitting device in which light extraction efficiency is not reduced is obtained. Further, since the step of heating in advance after fixing the light emitting element 112 to the recess bottom surface portion 319b of the package 318, the adhesion with the inner layer 415 fixed in the recess 319 is improved.

  A manufacturing process of the light emitting device 500 according to the fifth embodiment will be described with reference to FIGS. As described above, the light emitting device 500 is formed so that the surface of the sealing member 514 is covered with the silicone resin 517. Here, FIGS. 8A and 8B show a process in the case where the silicone resin 517 is provided. The formation method up to the outer layer 516 can be formed in the same manner as the light emitting device 400 according to the fourth embodiment described above. In FIG. 8A, the light emitting element 112 is fixed to the recess bottom surface portion 319b in the package 318, and the recess 319 is filled with the first low-melting glass to form the inner layer 515, and the second layer 515 is formed outside the second layer 515. An outer layer 516 is formed of low-melting glass, and a liquid silicone resin 817 is applied to the surface of the outer layer 516. Then, as in the case of the second low-melting glass, a mold 825 having an arbitrary shape is heated to the curing temperature of the liquid silicone resin 817 and gradually pressurized from the direction indicated by the arrow in the drawing. The surface of the sealing member 514 is covered. This state is maintained and gradually cooled to solidify the liquid silicone resin 817 to form the silicone resin 517. Then, the mold 825 was removed, and the light emitting device 500 as shown in FIG. 8B in which the sealing member 514 was covered with the silicone resin 517 was obtained. Moreover, it can replace with a silicone resin and can also provide multiple layers using 3rd low melting glass. Thus, when a plurality of layers are provided, the refractive index can be adjusted stepwise, and the light extraction efficiency can be improved. Further, a phosphor can be added to each of these layers to efficiently change the light from the light emitting element.

  FIG. 9A shows the first low melting point glass 915 heated and melted to the vicinity of the glass transition point (Tg) of the first low melting point glass 915 by fixing the light emitting element 112 to the recess bottom surface portion 319b of the package 318. This is a step of pouring into the recess 319. Here, for the purpose of converting the light from the light emitting element 112, a phosphor (not shown) or the like as described above may be added to the first low melting point glass 915 in advance.

  FIG. 9B shows a step of forming the first low-melting glass 915 of FIG. 9A using a mold 921. The mold 921 is heated above the glass transition point (Tg) of the first low melting point glass 915. Then, the mold 921 has a direction indicated by an arrow in the drawing so that the light emitting element 112 is gradually spread in the recess 319 so as to be embedded in the first low melting point glass 915 poured in the above-described process. While pressing, it is fixed at a certain position. And it cools in this state, the 1st low melting glass 915 is solidified, and the inner layer 315 is formed.

  Next, FIG. 9C is a step of applying a predetermined amount of the second low-melting glass 916 that has been heated and melted at the glass transition point or higher to the surface of the inner layer 315 formed in FIG. 9B. is there. Here, when a predetermined amount of the second low melting point glass 916 is applied, the entire inner layer 315, the light emitting element 112, and the package 318 may be heated to such an extent that the light emitting element 112 is not damaged. This is because, by heating, when the second low-melting glass 916 is applied, generation of bubbles or entrainment can be reduced. Then, the second low melting point glass 916 is formed using a mold 922. At this time, the mold 922 is heated to the glass transition point (Tg) or higher of the second low melting glass 916, and gradually pressurizes from the direction indicated by the arrow in the drawing, so that the second low melting glass 916 is placed inside. Spread on the surface of layer 315. At that time, the mold 922 is processed so that the second low melting point glass 916 has an arbitrary shape. Here, an R shape is used in order to improve the light extraction efficiency. Then, the mold 922 is pressurized so as to transfer the shape, and the mold 922 is gradually cooled until the second low melting point glass 916 is solidified while maintaining the pressurized state.

  When the mold 922 was removed after cooling, an outer layer 316 having a shape transferred could be obtained as shown in FIG. Here, when the outer layer 316 is in contact with the outermost layer of the sealing member 314, that is, the outside air, the second low-melting-point glass used contains an aluminum compound, in particular, alumina. It is preferable in terms of improvement.

FIG. 10 is the same as the manufacturing process shown in FIG. 6 up to the process of forming the inner layer 115, and the process of forming the outer layer 116 is different. That is, FIG. 10A shows a process of forming the outer layer 116 with the molds 930 and 931 so that the outer layer 116 is previously attached to the surface of the inner layer 115, and FIG. 10B shows the outer layer 116. Shows the step of crowning the inner layer 115. The outer layer 116 has a second low melting point between a mold 930 having a convex shape substantially the same as the outer shape of the inner layer 115 and a mold 931 having a digging 931a having the same shape as the outer layer 116. A glass 616 is poured to form. At this time, the molds 930 and 931 are heated to near the melting point of the second low melting point glass 616.
When the outer layer 116 is integrated with the preformed outer layer 116, the inner layer 115 is preferably heated to the glass transition point (Tg) to fix the interface between the outer layer 116 and the inner layer 115. Then, after being attached and fixed, the mold 931 is cooled to obtain the light emitting device 100. According to such a manufacturing method, the outer layer 116 can be formed in advance with a constant thickness, so that the thickness can be easily controlled.

  Here, the material of the mold used in each manufacturing process described above is not particularly limited, but considering the dimensional stability, ease of processing, etc., for example, the material may be cemented carbide, The surface of the mold may be platinum coated so that glass can be easily molded and removed. Also, in the cooling process after heating to form the shape, in order to adjust the cooling speed, water and oil circulation paths, heaters, thermocouples and other insertion paths for temperature control in the mold An attachment site or the like may be provided.

  Further, the method of previously forming the outer layer in the manufacturing process of FIG. 10 can also be applied to the case of forming the outer layer of the so-called surface mount type light emitting device shown in FIGS.

(Sample 1 to Sample 6)
Evaluation was performed using the light emitting device of FIG. As the package, a nitrided alumina package was prepared, and as the light emitting element, a light emitting element having a wavelength in the ultraviolet region as a main wavelength was prepared. A pair of wiring conductors spaced apart from each other is formed in the recess of the package, and one end of the wiring conductor is disposed on the bottom surface of the recess. Then, the wiring conductor and the light emitting element are fixed with a conductive paste in which silver filler is dispersed at the bottom surface of the concave portion of the package.

  The package and the light-emitting element fixed to the package are preliminarily heated at 150 ° C. and heated to 400 ° C. to melt an ammonia-based low-melting glass (glass transition point Tg: 200 ° C., refractive index 1.7). The light emitting device was embedded. Then, it is gradually cooled to 25 ° C. at a rate of 50 ° C./second to integrate the inner layer and the light emitting element.

  And an outer layer is formed using the low melting glass of the following samples 1-6. For the outer layer, each of the following samples is heated and melted in advance to the glass transition point (Tg), and poured into the upper surface of the inner layer integrated with the light-emitting element obtained above. Next, a mold heated in advance so as to have a glass transition point (Tg) of each sample described below is prepared. This mold is a mold having an R shape that covers the inner layer. Then, using this mold, each sample poured into the upper surface of the inner layer is pressurized from the upper side so as to spread on the upper surface of the inner layer, and the mold is fixed when the package and the mold contact each other. . Then, it is gradually cooled to 25 ° C. at a rate of 50 ° C./second, and the outer layers are solidified and integrated, and the mold is removed to obtain a light emitting device.

As an outer layer, low melting point glass material tin difluoride (SnF ₂ ), sodium hexametaphosphate ((NaPO ₃ ) ₆ ), aluminum metaphosphate (Al (PO ₃ ) ₃ ), alumina (hereinafter referred to as Al ₂ O ₃ ) Samples 1 to 6 were prepared by changing the addition amount.

Sample 1 is SnF ₂ : (NaPO ₃ ) ₆ : Al (PO ₃ ) ₃ = 14 g: 20 g: 1.5 g. Sample 2 Al ₂ O ₃ was 0.75 g (about 2 wt%), Sample 3 Al ₂ O ₃ was 1.50 g (about 4 wt%), and Sample 4 Al ₂ O ₃ was 2.25 g (about 6 wt%). Sample 5 was the same as Sample 1 except that Al ₂ O ₃ of Sample 5 was 3.00 g (about 7.8 wt%) and Al ₂ O ₃ of Sample 6 was 3.75 g (about 9.6 wt%).

The glass transition point (Tg: ° C.) of each sample was measured with an inspection scanning calorie balance. The results are summarized in Table 1, and the relationship between the added amount of Al ₂ O ₃ and the glass transition point is shown in a graph (FIG. 11).

It can be seen that the glass transition points of the low-melting glass samples 1 to 6 increase with an increase in the amount of post-added Al ₂ O ₃ . This is because the aluminum compound stabilizes the aluminum ions in the phosphoric acid amorphous glass network by combining the oxygen unpaired electrons of the phosphorus oxygen bonds in the phosphate glass with the aluminum ions, and the activation energy inside the amorphous is reduced. It is thought to be up. Therefore, it can be seen that an improvement in water resistance can be expected. Here, when the amount of alumina added is more than 2.0 g, the alumina dispersed in the low melting point glass becomes prominent in the low melting point glass as a white point. In such a case, the amount of alumina added is more preferably 2.0 g or less.

  All of the low melting point glasses of Sample 1 to Sample 6 have good translucency, and the light emitting device formed using the low melting point glass of Sample 1 to Sample 6 for the outer layer has good light extraction efficiency. . The water resistance of the outer layer was also good although experimental data was not shown, and the light emitting device was good without being affected by moisture.

(Sample 7 to Sample 13, Reference Example 1)
Evaluation was performed using the light emitting device of FIG. The prepared package, light emitting element, and the like are the same as those in the first embodiment, and are the same as those in the first embodiment until the light emitting element is fixed to the package in advance and heated at 150 ° C. in advance.

  Next, Sample 7 to Sample 13 and Reference Example 1 are prepared as inner layers. Each sample is heated and melted in advance to the glass transition point (Tg) of each sample. Then, each molten sample was injected into the recess of the package to embed the light emitting element. And it cools to 25 degreeC gradually at a speed | rate of 50 degreeC / sec, and obtains what integrated the inner layer and the light emitting element.

  As an outer layer, a low melting point glass (glass transition point Tg: 330 ° C., refractive index: 1.5) made of phosphate glass containing aluminum was prepared. This low-melting glass is heated and melted to the glass transition point, and the outer layer is formed in the same manner as in Example 1 to obtain a light emitting device.

Here, Sample 7 to Sample 13 are obtained by changing the amount of SnF ₂ added to the low melting point glass. The amount of SnF ₂ added to (Na ₂ PO ₃ ) ₆ in the low-melting glass is a weight ratio (SnF ₂ / (Na ₂ PO ₃ ) ₆ ), 0.11 for sample 7, 0.25 for sample 8, It is 0.43 for sample 9, 0.67 for sample 10, 1.00 for sample 11, 1.50 for sample 12, and 2.33 for sample 13. Further, as Reference Example 1, a material to which SnF ₂ is not added is prepared. The glass transition points (Tg: ° C.) of Samples 7 to 13 were measured with an inspection scanning calorimetric balance. The results are shown graphically in FIG. Moreover, the measurement of each refractive index of Sample 8 to Sample 11 and Reference Example 1 was performed with an Abbe refractometer (measurement wavelength d (589 nm)). The results are shown graphically in FIG.

  The glass transition points (Tg: ° C.) of Sample 7 to Sample 13 are 259.4 ° C., Sample 8 is 247.7 ° C., Sample 9 is 220 ° C., Sample 10 is 226 ° C., and Sample 11 is 216, respectively. C., Sample 12 was 202.degree. C., and Sample 13 was 146.degree. The refractive indexes of Sample 8 to Sample 11 and Reference Example 1 are 1.54 for Sample 8, 1.58 for Sample 9, 1.61 for Sample 10, 1.64 for Sample 11, and 1 for Reference Example 1. .48.

From the measurement results of each sample, it can be seen that the refractive index increases as the amount of SnF ₂ added increases (FIG. 13). Therefore, the refractive index can be adjusted depending on the amount added, which is useful when adjusting the light extraction efficiency. Moreover, since these refractive indexes are higher than the refractive index of an outer layer, although experimental data are not shown, the light extraction efficiency of the light-emitting light device formed using these samples is formed using Reference Example 1. It was better than the light emitting device. Moreover, since the low melting glass of Samples 7 to 13 had a low glass transition point (Tg), the light emitting element and the like were not damaged. It has been found that the glass transition point decreases as the amount of SnF ₂ added increases (FIG. 12). By adding SnF ₂ in this way, it is possible to adjust the glass transition point (Tg) of the low-melting glass used for the inner layer to a lower glass transition point (Tg) that does not damage the light emitting element or the like. I found out that

(A) The light-emitting device schematic end view of 1st Embodiment is shown. (B) The schematic end view of the light-emitting device which concerns on the modification of 1st Embodiment is shown. The schematic end view of the light-emitting device which concerns on 2nd Embodiment is shown. FIG. 6 shows a schematic end view of a light emitting device according to a third embodiment. FIG. 7 is a schematic end view of a light emitting device according to a fourth embodiment. The schematic end elevation of the light emitting device according to the fifth embodiment is shown. The schematic end elevation which shows an example of the manufacturing process of the light-emitting device of 1st Embodiment is shown. The schematic end view which shows an example of the manufacturing process of the light-emitting device of 4th Embodiment is shown. The schematic end view which shows a part of light-emitting device manufacturing process of 5th Embodiment is shown. The schematic end view which shows an example of the manufacturing process of the light-emitting device of 3rd Embodiment is shown. The schematic end view which shows a part of manufacturing process of the light-emitting device of 1st Embodiment is shown. The relationship figure of the addition amount of an alumina and a glass transition point (Tg) is shown. Added amount and the glass transition point of SnF ₂ shows a relationship diagram (Tg). It shows a relationship diagram of the addition amount and the refractive index of SnF _2.

Explanation of symbols

100, 110, 200, 300, 400, 500 ... Light emitting device 112 ... Light emitting element, 112a ... Light emitting surface 113 ... Terminal 114, 314, 414, 514 ... Sealing member 115, 315 415, 515 ... inner layer 116, 316, 416, 516 ... outer layer 117 ... further outer layer 217 ... devitrified glass layer 318 ... package 318a ... Upper surface side, 318b ... side surface side, 318c ... back side 319 ... recessed portion, 319a ... recessed portion side surface portion, 319b ... recessed portion bottom surface portion 415a ... upper surface 517 ... silicone resin 615, 715 , 915 ... 1st low melting glass 616, 716, 916 ... 2nd low melting glass 619 operation mold 620, 621, 725, 825, 921, 922, 30, 931 ... mold 620a, 621a ... cavity 715a ... upper surface, 715b ... housing part 723 ... first mold 724 ... second mold 725a ... Space 728 ... Third mold 729 ... Fourth mold 817 ... Liquid silicone resin 931a ... Digging

Claims (6)

In the light emitting device configured to emit light by applying a driving current to the light emitting element,
A sealing member having translucency covering the light emitting element;
The sealing member includes an inner layer disposed closer to the light emitting element, and an outer layer disposed outside the inner layer,
The refractive index of the inner layer is higher than the refractive index of the outer layer;
And the glass transition point of the said inner layer is lower than the glass transition point of the said outer layer, The light-emitting device characterized by the above-mentioned.   2. The light emitting device according to claim 1, wherein the inner layer has a refractive index of 1.5 or more and 2.5 or less and a glass transition point of 130 ° C. or more and 350 ° C. or less.   3. The light emitting device according to claim 1, wherein a main component of the inner layer is a first low-melting glass containing tin fluoride or tin oxide. 4.   The light emitting device according to claim 3, wherein a main component of the outer layer is a second low-melting glass containing an aluminum compound.   5. The light emitting device according to claim 4, wherein a part of the aluminum compound is alumina, and the alumina is contained in an amount of 0.5 wt% to 10 wt%.   The light emitting element is sealed by the sealing member inside a package having a recess, and the surface of the package and the surface of the sealing member are covered with a silicone resin. The light emitting device according to claim 1.

Images