JP6249335B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device including light emitting elements such as an LED chip (light emitting diode chip) and an LD chip (laser diode chip).

  Conventionally, as this type of light emitting device, for example, an LED device 151 having a configuration shown in FIG. 5 has been proposed (Patent Document 1).

  The LED device 151 includes a support 123, an LED chip 114, and an LED sealing resin body 117.

  The LED chip 114 is fixed to the support 123 with solder 127 or the like so that the emission surface 114a is on the support 123. The LED chip 114 is electrically connected to an electrode 122 provided on the support 123 by a bonding wire 121.

  The LED sealing resin body 117 includes a silicone resin 112, a phosphor 113, and a heat resistant material 115.

  The heat resistant material 115 suppresses the deterioration of the silicone resin 112 due to heat radiated from the LED chip 114 or ultraviolet rays. Patent Document 1 mentions cerium oxide, titanium oxide, and iron oxide as the heat-resistant material 115.

  In the LED sealing resin body 117, the phosphor 113 carrying the heat resistant material 115 is dispersed in the silicone resin 112. That is, the LED sealing resin body 117 includes the composite phosphor 116 in which the heat resistant material 115 is supported on the surface of the phosphor 113.

Japanese Patent No. 4980492

  In the field of light emitting devices, not only the LED device 151 but also further improvement of light extraction efficiency and higher light output are desired.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a light emitting device capable of improving heat resistance, improving light extraction efficiency, and increasing light output. .

The light-emitting device of the present invention includes a mounting substrate, a plurality of light-emitting elements mounted on the first surface side of the mounting substrate, and a plurality of the light-emitting elements covering each of the plurality of light-emitting elements on the first surface side of the mounting substrate. And a second cover layer interposed between adjacent first cover layers among the plurality of first cover layers on the first surface side of the mounting substrate. Each of the plurality of first cover layers is formed of a mixture of silicone resin and phosphor particles that emit light of different wavelengths by converting a part of the light emitted from the light emitting element. Yes. The second cover layer is transparent silicone resin, and cerium oxide nothing Ranaru particles, the mixture is formed by the light emitted from the light emitting element, wherein the adjacent first cover layer covers Let

  In the light emitting device, the second cover layer is preferably formed so as to include an intermediate point between two light emitting elements on both sides of the second cover layer among the plurality of light emitting elements.

  In this light emitting device, it is preferable that the thickness of the second cover layer is equal to or greater than the thickness of the first cover layer.

  In this light emitting device, the mounting substrate includes a support, a first conductor portion and a second conductor portion that are formed in a predetermined pattern on the first surface side of the support and the light emitting element is electrically connected thereto, The support is preferably made of a ceramic substrate or a metal substrate.

  In the light emitting device, the second cover layer preferably has a content of the particles of 1 wt% or less.

The light emitting device of the present invention, the first cover layer is formed of a mixture of a silicone resin, a cerium oxide-time or Ranaru particles. In the light emitting device of the present invention, the second cover layer is a mixture of a silicone resin and phosphor particles that emit light of different wavelengths by converting part of the light emitted from the light emitting element. It is formed by the body. Therefore, in the light emitting device of the present invention, it is possible to improve heat resistance, improve light extraction efficiency, and increase light output.

FIG. 1 is a schematic cross-sectional view illustrating a light emitting device according to an embodiment. FIG. 2 is a schematic plan view showing the light emitting device of the embodiment. FIG. 3 is a schematic cross-sectional view illustrating a first modification of the light emitting device of the embodiment. FIG. 4 is a schematic cross-sectional view showing a second modification of the light emitting device of the embodiment. FIG. 5 is a schematic cross-sectional view showing a conventional LED device.

  Below, the light-emitting device 1a of this embodiment is demonstrated based on FIG. 1 is a schematic cross-sectional view corresponding to the BB cross section of FIG.

The light emitting device 1 a includes a mounting substrate 2 and a plurality of light emitting elements 3 mounted on the first surface 2 a side of the mounting substrate 2. In addition, the light emitting device 1 a includes a plurality of first cover layers 41 covering the plurality of light emitting elements 3 on the first surface 2 a side of the mounting substrate 2, and a plurality of first covers on the first surface 2 a side of the mounting substrate 2. A second cover layer 42 interposed between adjacent first cover layers 41 of the cover layer 41. Each of the plurality of first cover layers 41 is formed of a mixture of silicone resin and phosphor particles that emit light of different wavelengths by converting a part of the light emitted from the light emitting element 3. Yes. The second cover layer 42 is formed of a mixture of a silicone resin and particles made of a material selected from the group consisting of cerium oxide (CeO ₂ ), titanium oxide (TiO ₂ ), iron oxide, and carbon. Therefore, the light emitting device 1a can improve heat resistance, improve light extraction efficiency, and increase light output.

  Each component of the light emitting device 1a will be described in more detail below.

  The light emitting element 3 is constituted by an LED chip 30. The LED chip 30 includes a substrate 31 and includes a multilayer film 32 formed of a semiconductor material on the first surface 31 a side of the substrate 31. The multilayer film 32 includes a first conductivity type semiconductor layer and a second conductivity type semiconductor layer. The multilayer film 32 is formed such that the first conductivity type semiconductor layer is closer to the first surface 31a of the substrate 31 than the second conductivity type semiconductor layer. In other words, the second conductivity type semiconductor layer is formed on the opposite side of the first conductivity type semiconductor layer from the substrate 31 side. In the LED chip 30, the first conductivity type semiconductor layer is composed of an n-type semiconductor layer, and the second conductivity type semiconductor layer is composed of a p-type semiconductor layer. In the LED chip 30, the first conductivity type semiconductor layer may be constituted by a p-type semiconductor layer, and the second conductivity type semiconductor layer may be constituted by an n-type semiconductor layer.

  The substrate 31 has a function of supporting the multilayer film 32. The multilayer film 32 can be formed by an epitaxial growth method or the like. As the epitaxial growth method, a crystal growth method can be adopted. Examples of the crystal growth method include metal organic vapor phase epitaxy (MOVPE) method, hydride vapor phase epitaxy (HVPE) method, molecular beam epitaxy (MBE) method, and the like. Can be adopted. The multilayer film 32 may contain impurities such as hydrogen, carbon, oxygen, silicon, and iron that are inevitably mixed when the multilayer film 32 is formed. The substrate 31 can be constituted by, for example, a crystal growth substrate when the multilayer film 32 is formed.

  The LED chip 30 is configured by a blue LED chip that emits blue light. When the LED chip 30 is composed of a GaN blue LED chip, for example, a GaN substrate can be adopted as the substrate 31. The GaN-based blue LED chip is an LED chip that employs a GaN-based material as the semiconductor material of the multilayer film 32. Examples of the GaN-based material include GaN, AlGaN, InAlGaN, and the like. The substrate 31 only needs to be formed of a material that can efficiently transmit light emitted from the multilayer film 32. For example, a sapphire substrate or the like can be used instead of the GaN substrate. In short, the substrate 31 is preferably a substrate that is transparent to the light emitted from the multilayer film 32. The LED chip 30 may have a configuration in which the multilayer film 32 includes a buffer layer interposed between the substrate 31 and the first conductivity type semiconductor layer. The LED chip 30 does not specifically limit the semiconductor material of the multilayer film 32. Further, the LED chip 30 does not particularly limit the emission wavelength. The LED chip 30 is not limited to a blue LED chip, and may be, for example, a purple LED chip that emits purple light.

  In the LED chip 30, the multilayer film 32 preferably includes a light emitting layer between the first conductive semiconductor layer and the second conductive semiconductor layer. In this case, the light emitted from the multilayer film 32 is light emitted from the light emitting layer, and the emission wavelength is defined by the material of the light emitting layer. The light emitting layer preferably has a single quantum well structure or a multiple quantum well structure, but is not limited thereto. For example, the LED chip 30 may form a double heterostructure with a first conductive semiconductor layer, a light emitting layer, and a second conductive semiconductor layer.

  The first conductivity type semiconductor layer is not limited to a single layer structure, and may have a multilayer structure. The second conductivity type semiconductor layer is not limited to a single layer structure, and may be a multilayer structure.

  The LED chip 30 is removed by etching a part of the multilayer film 32 from the surface side of the multilayer film 32 to the middle of the first conductivity type semiconductor layer. In short, the LED chip 30 has a mesa structure (not shown) formed by etching a part of the multilayer film 32. Thus, in the LED chip 30, a step is formed between the surface of the second conductivity type semiconductor layer and the surface of the first conductivity type semiconductor layer. The LED chip 30 has a first electrode formed on the exposed surface of the first conductive semiconductor layer, and a second electrode formed on the surface of the second conductive semiconductor layer. When the conductivity type (first conductivity type) of the first conductivity type semiconductor layer is n-type and the conductivity type (second conductivity type) of the second conductivity type semiconductor layer is p-type, the LED chip 30 is first The electrode and the second electrode constitute a negative electrode and a positive electrode, respectively. Further, in the LED chip 30, when the first conductivity type is p-type and the second conductivity type is n-type, the first electrode and the second electrode respectively constitute a positive electrode and a negative electrode. In any case, the LED chip 30 is provided with a first electrode and a second electrode on one surface side in the thickness direction of the LED chip 30.

  The chip size of the LED chip 30 is not particularly limited. When the planar shape is a rectangular shape, for example, a LED chip 30 having a chip size of 0.52 mm × 0.39 mm can be used. In addition, when the planar shape of the LED chip 30 is a square shape, for example, the chip size is 0.3 mm □ (0.3 mm × 0.3 mm), 0.45 mm □ (0.45 mm × 0.45 mm), 1 mm □. (1 mm × 1 mm) or the like can be used. The LED chip 30 is not limited to a planar shape or a chip size.

  The mounting substrate 2 is a substrate on which a plurality of light emitting elements 3 are mounted. “Mounting” is a concept that includes arranging and mechanically connecting a plurality of light emitting elements 3 and electrically connecting them.

  The mounting substrate 2 includes a support 20, a first conductor portion 23 and a second conductor portion 24 that are formed in a predetermined pattern on the first surface 20 a side of the support 20 and to which the plurality of light emitting elements 3 are electrically connected. . The mounting substrate 2 is formed so that the first conductor portion 23 and the second conductor portion 24 are spatially separated. The support 20 is preferably composed of a ceramic substrate 21. As a result, the light emitting device 1a can improve heat dissipation as compared with the case where the support 20 is made of a resin substrate, and the light output of the light emitting device 1a can be increased. Become.

  The first conductor portion 23 can be constituted by, for example, a laminated film of a Ni film 23a and an Au film 23b. The second conductor portion 24 can be constituted by, for example, a laminated film of a Ni film 24a and an Au film 24b. The first conductor part 23 and the second conductor part 24 are not limited to the laminated film of the Ni films 23a, 24a and the Au films 23b, 24b, for example, a laminated film of a Cu film, a Ni film, a Pd film, and an Au film, A laminated film of a Cu film, a Ni film, and an Au film, a laminated film of a Ti film, a Pt film, and an Au film can be employed. When the first conductor portion 23 and the second conductor portion 24 are formed of a laminated film, the uppermost layer film farthest from the support body 20 is formed of Au, and the lowermost layer film closest to the support body 20 is the support body. It is preferably formed of a material having high adhesiveness to 20. The 1st conductor part 23 and the 2nd conductor part 24 may be comprised not only with a laminated film but with a single layer film.

  In the light emitting device 1 a, the light emitting element 3 is bonded to the mounting substrate 2 via the bonding portion 5. Thus, in the light emitting device 1a, the light emitting element 3 is mechanically connected to the mounting substrate 2. The material of the bonding portion 5 is preferably a material having a high transmittance with respect to the light emitted from the light emitting element 3. For example, a silicone resin, an epoxy resin, a hybrid material of a silicone resin and an epoxy resin, or the like can be used. Thereby, the junction 5 can transmit the light emitted from the light emitting element 3.

  In the light emitting device 1 a, the light emitting element 3 is bonded to the mounting area of the light emitting element 3 on the support 20 through the bonding portion 5.

  The ceramic substrate 21 constituting the support 20 is formed in a flat plate shape. The ceramic substrate 21 has a diffusion property of light, and transmits or diffuses the light emitted from the light emitting element 3. As a material of the ceramic substrate 21, for example, translucent ceramics can be employed. As translucent ceramics, for example, alumina ceramics can be employed. The translucent ceramics can also adjust the transmittance, reflectance, refractive index, and thermal conductivity depending on the type and concentration of the binder, additive, and the like.

  The ceramic substrate 21 preferably has light diffusibility. Thereby, in the light emitting device 1 a, the light emitted from the light emitting element 3 to the ceramic substrate 21 side is diffused in the ceramic substrate 21. Therefore, the light emitting device 1a can further suppress the light emitted from the light emitting element 3 to the ceramic substrate 21 side from returning to the light emitting element 3. In addition, the light emitting device 1a can easily extract light from the peripheral region 202 of the projection region 201 of the light emitting element 3 on the first surface 20a of the support 20. Thereby, the light emitting device 1a can improve the light extraction efficiency, and can improve the total luminous flux. The projected region of the light emitting element 3 on the first surface 20 a of the support 20 means a region where the light emitting element 3 is projected onto the first surface 20 a of the support 20 along the thickness direction of the light emitting element 3. Further, light is emitted from the peripheral region 202 on the first surface 20a of the support 20 in a portion where the first conductor portion 23 and the second conductor portion 24 are not formed.

  The light emitting device 1a may be configured such that the mounting substrate 2 includes a reflective layer that reflects light from the light emitting element 3 on the second surface 20b of the support 20 constituted by the ceramic substrate 21. In addition, the light emitting device 1 a may be configured such that a reflective member that reflects light from the light emitting element 3 is disposed on the second surface 2 b of the mounting substrate 2. The reflective layer and the reflective member are preferably formed in an area wider than the vertical projection area of the first cover layer 41 on the second surface 20 b of the support 20 constituted by the ceramic substrate 21. As a result, the light emitting device 1a can suppress the light emitted from the light emitting element 3 and reflected by the reflective layer or the reflective member from being emitted without passing through the first cover layer 41. It becomes possible to suppress. “Color unevenness” is a state in which the chromaticity changes depending on the light irradiation direction. In the light emitting device 1a, it is preferable that the reflective layer and the reflective member are made of metal from the viewpoint of heat dissipation. In the light emitting device 1a, it is preferable that the reflective layer and the reflective member are formed in a wider area from the viewpoint of heat dissipation. As a result, the light emitting device 1a can conduct the heat generated in the light emitting element 3 and conducted to the reflective layer and the reflective member over a wider range, and the heat dissipation can be further improved. .

  The ceramic substrate 21 can be composed of, for example, an alumina substrate. In the alumina substrate, the particle diameter of the alumina particles is set to about 0.6 μm. The alumina substrate preferably has a particle size of alumina particles in the range of 0.5 μm to 5 μm. The alumina substrate tends to have a low reflectance as the particle size of the alumina particles increases, and the light scattering effect tends to increase as the particle size of the alumina particles decreases. In short, lowering the reflectance and increasing the scattering effect are in a trade-off relationship.

The particle size of the alumina particles is a value obtained from a number-based particle size distribution curve. The number-based particle size distribution curve is obtained by measuring the particle size distribution by an image imaging method. Specifically, the number-based particle size distribution curve is obtained by observing with a scanning electron microscope (SEM), obtaining an SEM image, and performing image processing on the SEM image. (Axis average diameter) and the number. In this number-based particle size distribution curve, the particle size value when the integrated value is 50% is called the median diameter (d ₅₀ ), and the particle size of the alumina particles means the median diameter.

  Theoretically, the relationship between the particle size of the spherical alumina particles on the alumina substrate and the reflectance tends to increase as the particle size decreases.

  For example, the mounting substrate 2 is formed by applying a first conductor portion 23 and a second conductor portion 24 to a thin film forming technique or plating on a ceramic substrate 21 composed of an alumina substrate fired at a firing temperature of about 1550 ° C. to 1600 ° C. It can be set as the structure formed by the technique etc.

  The planar shape of the mounting substrate 2 is a rectangular shape. The planar shape of the mounting substrate 2 is not limited to a rectangular shape, and may be, for example, a polygonal shape other than a rectangular shape, a circular shape, or the like.

  The light emitting device 1 a includes a plurality of light emitting elements 3 on the first surface 2 a side of the mounting substrate 2. As a result, the light emitting device 1a can increase the light output of the light emitting device 1a. When the light emitting element 3 is an LED chip, the light emitting device 1a constitutes an LED module. The LED module is defined in, for example, JIS Z9112: 2012.

  The light emitting device 1a can have a configuration in which a plurality of light emitting elements 3 are arranged in an array. FIG. 2 is a schematic plan view of a light emitting device 1a having a configuration in which a plurality of light emitting elements 3 are arranged in a two-dimensional array.

  In the light emitting device 1 a, a group of light emitting elements 3 connected in series among the plurality of light emitting elements 3 is arranged on a virtual line M <b> 1 connecting the first conductor portion 23 and the second conductor portion 24. In the light emitting device 1a, the first electrode of the light emitting element 3 closest to the first conductor portion 23 on the virtual line M1 is electrically connected to the first conductor portion 23 by the first wire 6a. In the light emitting device 1a, the second electrode of the light emitting element 3 closest to the second conductor portion 24 on the virtual line M1 is electrically connected to the second conductor portion 24 by the second wire 6b. The light emitting device 1a includes a second electrode of the light emitting element 3 on the first conductor portion 23 side and a first electrode of the light emitting element 3 on the second conductor portion 24 side among the light emitting elements 3 adjacent on the virtual line M1. The third wire 6c is electrically connected. Therefore, the light emitting device 1a reduces the light loss in the first conductor portion 23 and the second conductor portion 24 as compared to the case where the first conductor portion 23 and the second conductor portion 24 exist in the vicinity of each light emitting element 3. It becomes possible to suppress the light extraction efficiency and improve the light extraction efficiency. The loss of light in the first conductor portion 23 and the second conductor portion 24 is, for example, the first conductor of light emitted from the light emitting element 3 and directly incident on the first conductor portion 23 and the second conductor portion 24. There is an absorption loss in the portion 23 and the second conductor portion 24. The loss of light in the first conductor portion 23 and the second conductor portion 24 is, for example, incident on the ceramic substrate 21 from the light emitting element 3 and passes through the ceramic substrate 21 and the second conductor portion 23 and the second conductor portion 24. There is an absorption loss of light incident on the conductor portion 24 in the first conductor portion 23 and the second conductor portion 24. As the 1st wire 6a, the 2nd wire 6b, and the 3rd wire 6c, a gold wire, a silver wire, a copper wire, an aluminum wire etc. are employable, for example.

  The light emitting device 1a assumes a plurality of virtual lines M1, and four light emitting elements 3 are arranged as a group of light emitting elements 3 in each virtual line M1. In the example shown in FIG. 2, the number of virtual lines M1 is two. The light emitting device 1a employs a connection form in which a plurality of light emitting elements 3 are connected in series and parallel as a connection form in which a plurality of light emitting elements 3 are connected. The light emitting device 1a does not limit the connection form of the plurality of light emitting elements 3. For example, a connection form in which the plurality of light emitting elements 3 are connected in series may be employed, or the plurality of light emitting elements 3 are connected in parallel. The connected form may be adopted. The mounting substrate 2 only needs to include the first conductor portion 23 and the second conductor portion 24 that are formed in a predetermined pattern based on a predetermined connection form of the plurality of light emitting elements 3. The light emitting device 1a does not limit the number of virtual lines M1 or the number of light emitting elements 3 on the virtual line M1. In the light emitting device 1a, the light emitting elements 3 are arranged in a two-dimensional array. However, the light emitting device 1a is not limited thereto, and may be arranged in a one-dimensional array, for example. When the number of the light emitting elements 3 is one, the light emitting device 1a electrically connects the first electrode of the light emitting element 3 and the first conductor portion 23 via the first wire 6a, and the second electrode and the second conductor. It can be set as the structure electrically connected to the part 24 via the 2nd wire 6b.

  For example, the first cover layer 41 is preferably formed in a line shape so as to cover the light emitting element 3 arranged on the virtual line M1. The light emitting device 1a includes each first cover layer 41 and each second cover layer 42 disposed on the virtual line M1, and each light emitting element 3, the first wire 6a, and the second wire disposed on the virtual line M1. It also serves as a line-shaped sealing portion that covers 6b and each third wire 6c. Thereby, the light emitting device 1a can suppress the disconnection of each of the first wire 6a, the second wire 6b, and the third wire 6c, and can improve the reliability.

  The first cover layer 41 may be a semi-cylindrical shape, for example, as a line shape. In the light emitting device 1a, since the first cover layer 41 is formed in a semi-cylindrical shape, the light extraction efficiency can be improved and color unevenness can be suppressed.

  The shape of the surface of the first cover layer 41 is designed so that the angle formed between the normal of the point where the light rays from the light emitting element 3 intersect on the surface of the first cover 41 and the light rays becomes smaller than the critical angle. preferable. Here, the light emitting device 1a includes the first cover layer 41 so that the incident angle (light incident angle) of the light beam from the light emitting element 3 is smaller than the critical angle over substantially the entire surface of the first cover layer 41. It is preferable to design the shape of the surface.

  In the light emitting device 1a, it is preferable that the first cover layer 41 is designed so that the optical axis of the light emitting element 3 and the optical axis of the first cover layer 41 coincide. Thereby, the light emitting device 1a not only can suppress total reflection on the surface of the first cover layer 41 (the boundary surface between the first cover layer 41 and air) but also suppress uneven color. Is possible.

  The first cover layer 41 is not limited to a semi-cylindrical shape, and may be a hemispherical shape, a semi-elliptical spherical shape, a rectangular parallelepiped shape, or the like.

  The second cover layer 42 is interposed between two first cover layers 41 adjacent to each other on the virtual line M1. The second cover layer 42 has a columnar shape, but the shape is not particularly limited.

  In the light emitting device 1a, the first conductor portion 23 and the second conductor portion 24 are arranged to face each other in a comb shape, but the shapes of the first conductor portion 23 and the second conductor portion 24 are particularly limited. is not. The virtual line M1 is a straight line, but is not limited to a straight line, and may be a curved line, a line combining a straight line and a curved line, or the like.

  As described above, the first cover layer 41 is formed of a mixture of a silicone resin and phosphor particles that emit light of different wavelengths by converting the wavelength of part of the light emitted from the light emitting element 3. ing. The phosphor particles are excited by light emitted from the light emitting element 3 and emit light of a color different from that of the light emitting element 3. Thereby, the light emitting device 1a can obtain mixed color light of light emitted from the light emitting element 3 and light emitted from the phosphor particles. For example, when the light emitting device 1a employs a blue LED chip as the light emitting element 3 and employs yellow phosphor particles as the phosphor particles, white light can be obtained. That is, the light emitting device 1a can emit the blue light emitted from the light emitting element 3 and the yellow light emitted from the yellow phosphor particles from the first cover layer 41, thereby obtaining white light. .

The phosphor particles are not limited to yellow phosphor particles, and for example, yellow phosphor particles and red phosphor particles may be employed. As yellow phosphor particles, for example, Ce ³⁺ activated YAG (Yttrium Aluminum Garnet) phosphor particles, Eu ²⁺ activated oxynitride phosphor particles, and the like can be used. Examples of the Ce ³⁺ activated YAG phosphor include Y ₃ Al ₅ O ₁₂ : Ce ³⁺ . Examples of Eu ²⁺ activated oxynitride phosphors include SrSi ₂ O ₂ N ₂ : Eu ²⁺ . As the red phosphor particles, for example, particles of Eu ²⁺ activated nitride phosphor can be employed. Examples of the Eu ²⁺ activated nitride phosphor include (Sr, Ca) AlSiN ₃ : Eu ²⁺ and CaAlSiN ₃ : Eu ²⁺ .

Further, the phosphor particles are not limited to one kind of yellow phosphor particles, and two kinds of yellow phosphor particles having different emission peak wavelengths may be employed. The light emitting device 1a can improve color rendering by adopting a plurality of types of phosphor particles as the wavelength conversion material. Further, as the phosphor particles, red phosphor particles and green phosphor particles may be adopted. Examples of the green phosphor particles include CaSc ₂ O ₄ : Ce ³⁺ , Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce ³⁺ , (Ca, Sr, Ba) Al ₂ O ₄ : Eu ²⁺ , SrGa. Phosphor particles such as ₂ S ₄ : Eu ²⁺ can be employed.

  The phosphor particles preferably have an average particle size in the range of 1 μm to 10 μm, for example. As the phosphor particles have a larger average particle diameter, the defect density tends to be smaller, energy loss is reduced, and the luminous efficiency tends to be higher. For this reason, it is preferable to employ phosphor particles having an average particle diameter of 5 μm or more from the viewpoint of luminous efficiency. The average particle diameter of the phosphor particles is an average particle diameter on a volume basis measured by a dynamic light scattering method.

  The first cover layer 41 preferably has a phosphor particle content in the range of 3 wt% to 50 wt%, for example.

As described above, the second cover layer 42 is formed of a mixture of silicone resin and cerium oxide particles. The second cover layer 42 may be formed of a mixture of a silicone resin and particles made of a material selected from the group of cerium oxide, titanium oxide, iron oxide, and carbon. In the second cover layer 42 , particles made of a material selected from the group of cerium oxide, titanium oxide, iron oxide, and carbon are dispersed in a transparent layer formed of a silicone resin. As carbon, for example, carbon black, graphite or the like can be employed. In the second cover layer 42, the content of particles made of a material selected from the group of cerium oxide, titanium oxide, iron oxide, and carbon is preferably 1 wt% or less. Thereby, the light emitting device 1a can suppress the light transmittance of the second cover layer 42 from being excessively lowered. Therefore, the light emitting device 1a is lighter than the case where the content of particles made of a material selected from the group of cerium oxide, titanium oxide, iron oxide, and carbon in the second cover layer 42 is larger than 1 wt%. The extraction efficiency can be improved. The second cover layer 42 is not limited to including one type of particles made of a material selected from the group of cerium oxide, titanium oxide, iron oxide, and carbon, and may include a plurality of types. For example, the second cover layer 42 may be formed of a mixture of silicone resin, cerium oxide particles, and titanium oxide particles.

  As the silicone resin of the first cover layer 41 and the second cover layer 42, for example, a thermosetting silicone resin, a two-component curable silicone resin, a photocurable silicone resin, or the like can be used.

  The mixed color light emitted from the light emitting device 1a can be set based on, for example, the correlated color temperature of the light source color of the LED defined by JIS Z9112: 2012. In JIS Z9112: 2012, the light source colors of LEDs are classified into five types of daylight color, daylight white, white, warm white, and light bulb color according to chromaticity in the XYZ color system.

  In manufacturing the light emitting device 1a, first, the mounting substrate 2 is prepared, and then the following first, second, and third steps are sequentially performed. In the first step, the light emitting element 3 as a die is bonded to the first surface 2a of the mounting substrate 2 via the bonding portion 5 by a die bonding apparatus or the like. In the second step, wire bonding for forming the first wire 6a, the second wire 6b, and the third wire 6c is performed by a wire bonding apparatus or the like. In the third step, the first cover layer 41 and the second cover layer 42 are formed using a dispenser system or the like. In the third step, first, the first cover layer 41 is formed, and then the second cover layer 42 is formed.

  When the first cover layer 41 is formed by the dispenser system, for example, the material of the first cover layer 41 is discharged from the nozzle and applied while moving the dispenser head along the arrangement direction of the light emitting elements 3. The material of the first cover layer 41 is a silicone resin kneaded with phosphor particles.

  Here, when the material of the first cover layer 41 is applied by the dispenser system so as to have an application shape based on the surface shape of the first cover layer 41, for example, the material is discharged while moving the dispenser head. What is necessary is just to apply.

  The dispenser system controls a moving mechanism that moves the dispenser head, a sensor unit that measures the height of each of the first surface 2a of the mounting substrate 2 and the nozzle from the table, and the amount of material discharged from the moving mechanism and the nozzle. And a controller. The moving mechanism can be configured by a robot, for example. The controller can be realized, for example, by mounting an appropriate program on a microcomputer. In addition, the dispenser system corresponds to a plurality of types of products having different arrangements of the light emitting elements 3, the number of light emitting elements 3, the line width of the first cover layer 41, and the like by appropriately changing the program installed in the controller. It becomes possible.

  The surface shape of the first cover layer 41 formed using the dispenser system can be controlled by adjusting, for example, the viscosity of the material. The curvature of the surface (convex curved surface) of the first cover layer 41 can be designed according to the viscosity and surface tension of the material of the first cover layer 41, the height of the first wire 6a, the second wire 6b, and the third wire 6c. It is. Increasing the curvature can be realized, for example, by increasing the viscosity of the material, increasing the surface tension, or increasing the height of the first wire 6a, the second wire 6b, and the third wire 6c. . In addition, the width (line width) of the line-shaped second cover layer 42 can be reduced by increasing the viscosity of the material or increasing the surface tension. The viscosity of the material of the first cover layer 41 is preferably set in the range of about 100 to 2000 mPa · s. As the viscosity value, for example, a value measured at room temperature using a conical plate type rotational viscometer can be adopted.

  When the second cover layer 42 is formed by the dispenser system, for example, the dispenser head is moved along the arrangement direction of the light emitting elements 3 and positioned vertically above the light emitting elements 3, and then the second cover layer is formed from the nozzle. 42 material is discharged and applied. The material of the second cover layer 42 is a silicone resin in which particles made of a material selected from the group consisting of cerium oxide, titanium oxide, iron oxide, and carbon are kneaded.

  By the way, it is preferable that the average particle diameter of particles made of a material selected from the group of cerium oxide, titanium oxide, iron oxide, and carbon is 10 μm or less. In the light emitting device 1a, when the average particle diameter of the particles is larger than 10 μm, when the material of the second cover layer 42 is applied so as to cover the light emitting element 3 by the dispenser system, the particles are easily settled, and the particle size is 10 μm or less. If so, the dispersibility can be improved. The average particle diameter of particles made of a material selected from the group consisting of cerium oxide, titanium oxide, iron oxide and carbon is preferably 1 μm or more. The average particle diameter of the particles is an average particle diameter on a volume basis measured by a dynamic light scattering method.

  The dispenser system may also include a heater that heats the uncured material to a desired viscosity. Thereby, the dispenser system can improve the reproducibility of the application shape of the material, and can improve the reproducibility of the surface shapes of the first cover layer 41 and the second cover layer 42, respectively.

  The light emitting device 1a of the present embodiment described above includes a plurality of light emitting elements 3. Thereby, the light emitting device 1a can increase the light output as compared with the case where the number of the light emitting elements 3 is one.

  Further, in the light emitting device 1a, each of the plurality of first cover layers 41 includes a silicone resin, a phosphor particle that emits light of a different wavelength by converting a part of the light emitted from the light emitting element 3, and It is formed of a mixture of In the light emitting device 1a, the second cover layer 42 is formed of a mixture of a silicone resin and particles made of a material selected from the group of cerium oxide, titanium oxide, iron oxide, and carbon. Therefore, when the sealing part including the first cover layer 41 and the second cover layer 42 contracts due to the temperature change of each light emitting element 3, the light emitting device 1 a has both sides on the second cover layer 42. Tensile stress is applied from the first cover layer 41. However, in the light emitting device 1a, the second cover layer 42 is formed of a mixture of silicone resin and particles made of a material selected from the group of cerium oxide, titanium oxide, iron oxide, and carbon. Thereby, the light emitting device 1a includes the second cover layer 42 as compared with the case where the second cover layer 42 is formed of only the silicone resin or the mixture of the silicone resin and the phosphor particles. Thermal degradation of the silicone resin 42 is suppressed. For this reason, the light emitting device 1a can suppress the loss of the elasticity of the silicone resin of the second cover layer 42, and can suppress the occurrence of cracks. Therefore, the light emitting device 1a can improve heat resistance.

  Further, in the light emitting device 1a, the first cover layer 41 is a mixture of a silicone resin and phosphor particles that radiate light of different wavelengths by converting part of the light emitted from the light emitting element 3. Is formed. Thereby, the light emitting device 1a has the first cover layer 41 in which the first cover layer 41 has a structure in which particles made of a material selected from the group of cerium oxide, titanium oxide, iron oxide, and carbon are dispersed. It becomes possible to increase the light transmittance. Further, the light emitting device 1a has a light transmittance of the first cover layer 41 as compared with the configuration in which the phosphor particles carry particles made of a material selected from the group of cerium oxide, titanium oxide, iron oxide, and carbon. Can be increased. Therefore, the light emitting device 1a can improve the light extraction efficiency.

  As an estimated mechanism for improving the heat resistance of the second cover layer 42 alone, a mechanism in which particles such as cerium oxide improve the heat resistance of the silicone resin is conceivable. In the presumed mechanism, even if radicals that cause the oxidation reaction of the silicone resin are generated in the silicone resin due to the heat generated in the light emitting element 3, the ions contained in the particles react with the radicals and are reduced. Thus, curing deterioration due to oxidation of the silicone resin is suppressed. For example, when the particles are cerium oxide, the ions contained in the particles are cerium ions. Note that the light emitting device 1a of the present embodiment is within the scope of the present invention even if the estimation mechanism is different.

  The second cover layer 42 is preferably formed so as to include an intermediate point between two light emitting elements 3 on both sides of the second cover layer 42 among the plurality of light emitting elements 3. Thus, the light emitting device 1a can reduce the difference in tensile stress from the first cover layer 41 on both sides of the second cover layer 42, and can further improve the heat resistance.

  In the light emitting device 1 a, the thickness of the second cover layer 42 is preferably equal to or greater than the thickness of the first cover layer 41. Thereby, the light emitting device 1a can further suppress the occurrence of cracks in the first cover layer 41, and can further improve the heat resistance. In the example of FIG. 1, the thickness of the second cover layer 42 is slightly larger than the thickness of the first cover layer 41.

  In the light emitting device 1a, the mounting substrate 2 is formed in a predetermined pattern on the support 20 and the first surface 20a side of the support 20, and the first conductor portion 23 and the first conductor portion 23 to which the light emitting element 3 is electrically connected. The support body 20 is configured by a ceramic substrate 21. As a result, the light emitting device 1a can improve heat dissipation, improve the reliability, and increase the light output of the light emitting device 1a, compared to the case where the support 20 is a resin substrate. Can be achieved.

  In the light emitting device 1a, the joint portion 5 may be formed of a mixture of a silicone resin and particles made of a material selected from the group of cerium oxide, titanium oxide, iron oxide, and carbon. As a result, the light emitting device 1a can improve the heat resistance of the joint portion 5, can suppress the occurrence of cracks in the joint portion 5, and further improve the reliability of the light emitting device 1a. Is possible. The average particle diameter of particles made of a material selected from the group consisting of cerium oxide, titanium oxide, iron oxide and carbon is preferably 10 μm or less. Moreover, it is preferable that the average particle diameter of particle | grains is 1 micrometer or more. In the joint portion 5, the content of particles made of a material selected from the group of cerium oxide, titanium oxide, iron oxide, and carbon is preferably 1 wt% or less. Thereby, the light-emitting device 1a can suppress that the light transmittance of the junction part 5 falls too much.

  FIG. 3 is a schematic cross-sectional view showing a light emitting device 1b of a first modification of the light emitting device 1a. The light emitting device 1b has substantially the same basic configuration as the light emitting device 1a. The light emitting device 1b is different from the light emitting device 1a in that the support 20 on the mounting substrate 2 is formed of a metal substrate 25. In addition, in the light-emitting device 1b, about the component similar to the light-emitting device 1a, the code | symbol same as the light-emitting device 1a is attached | subjected and description is abbreviate | omitted.

  As the metal substrate 25, for example, an aluminum substrate, a copper substrate, or the like can be adopted. The support 20 has an electrical insulating layer 26 formed on the surface of a metal substrate 25. In the mounting substrate 2, the first conductor portion 23 and the second conductor portion 24 are formed on the electrical insulating layer 26. The mounting substrate 2 can be formed by a metal base printed wiring board, for example.

  In the light emitting device 1b, the mounting substrate 2 is formed in a predetermined pattern on the support 20 and the first surface 20a side of the support 20, and the first conductor portion 23 and the second conductor to which the light emitting element 3 is electrically connected. And the support 20 is constituted by a metal substrate 25. As a result, the light emitting device 1b can improve heat dissipation, improve reliability, and increase the light output of the light emitting device 1b as compared with the case where the support 20 is a resin substrate. Can be achieved.

The mounting substrate 2 can be configured to include a white resist layer 27. For example, the resist layer 27 can cover the portion of the electrical insulating layer 26 where none of the first cover layer 41, the first conductor portion 23, and the second conductor portion 24 is formed. As a material of the resist layer 27, for example, a white resist can be adopted. Examples of the white resist include a resin containing a white pigment. Examples of the white pigment include barium sulfate (BaSO ₄ ) and titanium dioxide (TiO ₂ ). Examples of the resin include a silicone resin. As the white resist, for example, “ASA COLOR (registered trademark) RESIST INK”, which is a white resist material made of silicone manufactured by Asahi Rubber Co., Ltd., can be used. The resist layer 27 can be formed by, for example, a coating method.

  Since the light emitting device 1 b includes the white resist layer 27, the light incident on the mounting substrate 2 from the light emitting element 3 is easily reflected on the surface of the resist layer 27. Thereby, the light emitting device 1b can suppress the light emitted from the light emitting element 3 from being absorbed by the mounting substrate 2. Therefore, the light emitting device 1b can improve the light output by improving the light extraction efficiency to the outside.

  The light emitting device 1 b may have a configuration in which the light emitting element 3 is bonded to the metal substrate 25 via the bonding portion 5. Thereby, the light emitting device 1b forms a heat transfer path for transferring the heat generated in the light emitting element 3 to the metal substrate 25 without passing through the electric insulating layer 26 as a heat transfer path of the heat generated in the light emitting element 3. Is done. Therefore, the light emitting device 1b can improve heat dissipation.

  The light emitting device 1b may have a configuration in which the light emitting element 3 is mounted on the metal substrate 25 via a plate-like submount member (not shown). The material of the submount member is preferably a material having a higher thermal conductivity than the electrical insulating layer 26 and a smaller difference in linear expansion coefficient from the light emitting element 3 than the metal substrate 25. As a result, the light emitting device 1b transfers heat generated in the light emitting element 3 to the submount member and the metal substrate 25 without passing through the electrical insulating layer 26 as a heat transfer path for heat generated in the light emitting element 3. A thermal path is formed. Therefore, the light emitting device 1b can improve heat dissipation. As a material of the submount member, for example, AlN can be adopted. What is necessary is just to join a submount member and the metal substrate 25 via a junction part. As a material for the joining portion that joins the submount member and the metal substrate 25, for example, lead-free solder such as AuSn or SnAgCu is preferable. When the light-emitting device 1b employs AuSn as a material for the joining portion that joins the submount member and the metal substrate 25, a metal layer made of Au or Ag is formed on the joining surface of the surface of the metal substrate 25 at the time of manufacture. Preprocessing is required.

  FIG. 4 is a schematic plan view showing a light emitting device 1c of a second modification of the light emitting device 1a. The light emitting device 1c has substantially the same basic configuration as the light emitting device 1a. The light emitting device 1c is different from the light emitting device 1a in that the number of virtual lines M1 is three and the second cover layer 42 has a net shape. In addition, in the light-emitting device 1c, about the component similar to the light-emitting device 1a, the code | symbol same as the light-emitting device 1a is attached | subjected and description is abbreviate | omitted.

  In the light emitting device 1c, one first cover layer 41 is located on each mesh of the second cover layer 42 formed in a net shape.

  Like the light emitting device 1a, the light emitting device 1c has a plurality of light emitting elements 3 each covered with the first cover layer 41, and the second cover layer 42 is interposed between the adjacent first cover layers 41. It is possible to improve the performance, improve the light extraction efficiency, and increase the light output.

  By the way, the light emitting devices 1a, 1b, and 1c can be used as light sources of various lighting devices. As a lighting device, for example, a lighting device in which any one of the light emitting devices 1a, 1b and 1c is used as a light source, a lamp (for example, a straight tube LED lamp, a light bulb lamp, etc.), etc. However, other lighting devices may be used.

  The light emitting devices 1a, 1b, and 1c use the light emitting element 3 in which the first electrode and the second electrode are provided on one surface side in the thickness direction, but are not limited thereto. As the light emitting element 3, a structure in which the first electrode is formed on one surface side in the thickness direction of the light emitting element 3 and the second electrode is formed on the other surface side may be used.

  Moreover, although the light emitting devices 1a, 1b, and 1c employ the LED chip 30 as the light emitting element 3, the present invention is not limited thereto, and for example, an LD chip may be employed.

  Each figure explained in the above-mentioned embodiment etc. is typical, and the ratio of each size and thickness of each component does not necessarily reflect the actual size ratio. In addition, the materials, numerical values, and the like described in the embodiments and the like are merely preferable examples and are not limited thereto. Furthermore, the present invention can be appropriately modified in configuration without departing from the scope of its technical idea.

DESCRIPTION OF SYMBOLS 1a, 1b, 1c Light-emitting device 2 Mounting board | substrate 2a 1st surface 3 Light emitting element 5 Junction part 20 Support body 20a 1st surface 21 Ceramic substrate 23 1st conductor part 24 2nd conductor part 41 1st cover layer 42 2nd cover layer

Claims (5)

A mounting substrate, a plurality of light emitting elements mounted on the first surface side of the mounting substrate, and a plurality of first cover layers covering each of the plurality of light emitting elements on the first surface side of the mounting substrate, A second cover layer interposed between adjacent first cover layers among the plurality of first cover layers on the first surface side of the mounting substrate, and
Each of the plurality of first cover layers is formed of a mixture of silicone resin and phosphor particles that emit light of different wavelengths by converting a part of the light emitted from the light emitting element.
The second cover layer is transparent silicone resin, and cerium oxide nothing Ranaru particles, the mixture is formed by the light emitted from the light emitting element, wherein the adjacent first cover layer covers Let
A light emitting device characterized by that. The second cover layer is formed so as to include an intermediate point between two light emitting elements on both sides of the second cover layer among the plurality of light emitting elements.
The light-emitting device according to claim 1. The thickness of the second cover layer is equal to or greater than the thickness of the first cover layer.
The light emitting device according to any one of claims 1 and 2. The mounting substrate includes a support, and a first conductor portion and a second conductor portion that are formed in a predetermined pattern on the first surface side of the support and to which the light emitting element is electrically connected. The body is composed of a ceramic substrate or a metal substrate,
The light-emitting device according to any one of claims 1 to 3. The second cover layer has a content of the particles of 1 wt% or less.
The light emitting device according to claim 1, wherein the light emitting device is a light emitting device.

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