Patent Publication Number: US-2020295242-A1

Title: Light-emitting device and production method therefor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2019-048979, filed on Mar. 15, 2019, the disclosure of which is hereby incorporated by reference in its entirety. 
     BACKGROUND 
     The present disclosure relates to light-emitting devices and methods of producing light-emitting devices. 
     Characteristics required for light-emitting devices include reduced unevenness in chromaticity. For example, PCT Publication No. WO 2012/099145 describes a light-emitting device that includes a plurality of light-emitting elements disposed on a substrate, a resin body covering each light-emitting element, and a light-diffusing member disposed on a surface of each resin body opposite to the light emission surface of the corresponding light-emitting element. In PCT Publication No. WO 2012/099145, diffusion of light is controlled by the light-diffusing member, and the distribution of light is controlled by controlling the shape of the resin body, so that unevenness in luminance and chromaticity of emitted light can be reduced. 
     While PCT Publication No. WO 2012/099145 is related to a light-emitting device mainly used for a backlight device, etc., it may also be desirable to reduce unevenness in chromaticity in a light-emitting device in which a light-emitting element is disposed in a recess of a package and the recess is sealed with a resin. 
     SUMMARY 
     Certain embodiments of the present disclosure allow for providing a light-emitting device that includes a light-emitting element in a recess of a package, and in which light distribution unevenness is reduced, and a method of producing the light-emitting device. 
     A method of producing a light-emitting device according to one embodiment of the present disclosure includes: providing a package having an upper surface, and a recess including an opening located at the upper surface; disposing a light-emitting element on a bottom surface of the recess of the package; disposing an uncured sealing member in the recess of the package; and curing the uncured sealing member while applying a centrifugal force to the package in which the uncured sealing member are disposed, such that the centrifugal force is applied in a direction perpendicular to the upper surface toward the bottom surface of the recess. 
     A light-emitting device according to one embodiment of the present disclosure includes a package having an upper surface and defining a recess including an opening in the upper surface, a light-emitting element disposed on a bottom surface of the recess of the package, and a sealing member disposed in the recess of the package and covering the light-emitting element. The upper surface of the sealing member includes a flat region. The flat region includes at least a region located above the light-emitting element. The flat region is located below the upper surface of the package. 
     According to certain embodiments of the present disclosure, provided are a light-emitting device in which a light-emitting element is disposed in a recess and unevenness in chromaticity of emitted light is reduced, and a method of producing the light-emitting device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic perspective view showing a light-emitting device produced using a method of producing a light-emitting device according to the present disclosure. 
         FIG. 1B  is a schematic bottom view of the light-emitting device of  FIG. 1A . 
         FIG. 2A  is a schematic plan view of the light-emitting device of  FIG. 1A  in which illustration of a sealing member and light reflective member is omitted. 
         FIG. 2B  is a schematic cross-sectional view of the light-emitting device taken along line  2 B- 2 B of  FIG. 2A . 
         FIG. 2C  is a schematic enlarged cross-sectional view of a portion at and near an end portion of the sealing member of  FIG. 2B . 
         FIG. 3A  is a schematic cross-sectional view of a conventional light-emitting device. 
         FIG. 3B  is a schematic enlarged view of a portion at and near an end portion of a sealing member of  FIG. 3A . 
         FIG. 3C  is a schematic diagram for describing the incidence of light to an upper surface of a sealing member of a light-emitting device according to an embodiment. 
         FIG. 3D  is a schematic diagram for describing the incidence of light to an upper surface of a sealing member of a conventional light-emitting device. 
         FIG. 4  is a flowchart showing production steps in a method of producing the light-emitting device of the present disclosure. 
         FIG. 5A  is a schematic cross-sectional view for describing a step of preparing a package in the method of producing the light-emitting device. 
         FIG. 5B  is a schematic cross-sectional view for describing a step of disposing a light-emitting element in the method of producing the light-emitting device. 
         FIG. 5C  is a schematic cross-sectional view for describing a step of disposing a light reflective member in the method of producing the light-emitting device. 
         FIG. 5D  is a schematic cross-sectional view for describing a step of disposing an uncured sealing member in the method of producing the light-emitting device. 
         FIG. 5E  is a schematic cross-sectional view for describing a step of curing the uncured sealing member in the method of producing the light-emitting device. 
         FIG. 6A  is another cross-sectional view for describing a step of preparing a package in the method of producing the light-emitting device. 
         FIG. 6B  is a schematic plan view of a lead frame used in the step of preparing a package in the method of producing the light-emitting device. 
         FIG. 6C  is a schematic plan view of a lead frame having a resin used in the step of preparing a package in the method of producing the light-emitting device. 
         FIG. 6D  is a schematic plan view of a lead frame having a resin used in a step of separating into individual packages in the method of producing the light-emitting device. 
         FIG. 7A  is a schematic diagram showing an oven used in the method of producing the light-emitting device. 
         FIG. 7B  is a schematic diagram showing how a centrifugal force is applied to the package using the oven in the method of producing the light-emitting device. 
         FIG. 7C  is another schematic diagram showing how a centrifugal force is applied to the package using the oven in the method of producing the light-emitting device. 
         FIG. 8  is a diagram showing the light distribution angle dependency of chromaticity deviation in the light-emitting device of the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The inventors have extensively studied unevenness in chromaticity of emitted light that occurs in a light-emitting device in which a light-emitting element is disposed in a recess of a package, and the recess is sealed with a resin. As a result, the present inventors have found that the uneven chromaticity of light emitted from the light-emitting device is attributed to the shape of a surface of the sealing resin. The inventors have devised a light-emitting device having a novel structure and a method of producing the light-emitting device. 
     Certain embodiments of a method of producing a light-emitting device according to the present disclosure will now be described with reference to the accompanying drawings. The light-emitting device to be described below is merely illustrative, and various changes and modifications can be made thereto. The dimensions, shapes, etc., of elements shown in the drawings may be exaggerated for clarity. The dimensions, shapes, etc., of the elements of the light-emitting device and manufacturing device to be described below are not necessarily drawn to scale. For example, the dimensions of some of the elements of the light-emitting module relative to the other elements may be exaggerated. Some of the elements may not be shown, in order to avoid excessively complicating the drawings. 
     Structure of Light-Emitting Device 
     Embodiments of a light-emitting device according to the present disclosure will be described.  FIG. 1A  is a schematic perspective view showing one embodiment of the light-emitting device according to the present disclosure.  FIG. 1B  is a schematic bottom view of the light-emitting device of  FIG. 1A .  FIG. 2A  is a schematic plan view of the light-emitting device of  FIG. 1A  in which illustration of a sealing member and light reflective member is omitted.  FIG. 2B  is a schematic cross-sectional view of the light-emitting device taken along line  2 B- 2 B of  FIG. 2A .  FIG. 2C  is an enlarged cross-sectional view of a portion of  FIG. 2B . The light-emitting device  101  includes a package  10 , a light-emitting element  20 , and a sealing member  30 . The light-emitting device  101  may further include a light reflective member  15  and a protective element  40 . 
     Package  10   
     The package  10  serves as a housing that houses the light-emitting element  20 . The package  10  has an upper surface  10   a  and a lower surface  10   b , and defines a recess  11  having an opening  11   a  located in the upper surface  10   a . In this embodiment, the upper surface  10   a  has an outer periphery having a substantially rectangular shape, and the package  10  has four lateral surfaces  10   c - 10   f  corresponding to the four sides of the rectangular shape of the upper surface  10   a.    
     In this embodiment, the package  10  includes an insulating base body  13  and lead terminals  14 A and  14 B. The base body  13  includes a portion of a surface  11   b  defining a bottom of the recess  11 , and an inner lateral surface  11   c  defining the recess  11 . The upper surface  10   a  of the package  10  may be provided with a protrusion or recess, a groove surrounding the opening  11   a , etc. A portion of each of the lead terminals  14 A and  14 B is exposed from the surface  11   b  defining the bottom of the recess  11 . 
     The base body  13  is formed of an insulating material. The base body  13  is also preferably formed of a material that does not easily transmit light from the light-emitting element  20  and external light. The base body  13  is a main part that maintains the structure of the package  10 , and therefore, preferably has a predetermined strength. The base body  13  is formed of, for example, a thermosetting resin, thermoplastic resin, ceramic, or the like. More specifically, the base body  13  is formed of a resin material, such as an epoxy resin, silicone resin, phenolic resin, glass epoxy resin, BT resin, or PPA, or a ceramic material, such as alumina or aluminum nitride. Alternatively, the base body  13  may be formed of a material that reflects light from the light-emitting element  20  on the inner lateral surface  11   c  defining the recess  11 . In other words, the inner lateral surface  11   c  may be formed of another member that has a higher reflectance to light emitted by the light-emitting element  20  than that of a material of the outer surface of the base body  13 . This allows for improving the light extraction efficiency of the light-emitting device  101 . 
     The lead terminals  14 A and  14 B serve as a terminal for electrically connecting the light-emitting element  20  to a wiring external to the package  10 . The package  10  includes at least one pair of lead terminals  14 A and  14 B. A portion of each of the lead terminals  14 A and  14 B is exposed from the outer surface of the package  10 , and another portion of each of the lead terminals  14 A and  14 B is embedded in the base body  13 . In this embodiment, the lead terminal  14 A has end surfaces  14 Ac,  14 Ae, and  14 Af that are exposed from the lateral surfaces  10   c ,  10   e , and  10   f  of the package  10 , respectively. The lead terminal  14 B has end surfaces  14 Bd,  14 Be, and  14 Bf that are exposed from the lateral surfaces  10   d ,  10   e , and  10   f  of the package  10 , respectively. As described below, during production of the light-emitting device  101 , the package  10  is formed from a lead frame having a resin in which a plurality of packages  10  are integrally formed. The lateral surfaces  10   c ,  10   d ,  10   e , and  10   f  of the package  10  and the end surfaces  14 Ac,  14 Bd,  14 Ae, and  14 Af exposed from the lateral surfaces  10   c ,  10   d ,  10   e , and  10   f  of the package  10 , respectively, are formed by cutting the lead frame with a resin. Employing such a lead frame in which a plurality of packages are joined together allows for simultaneously manufacturing a plurality of light-emitting devices. 
     As described above, each of the lead terminals  14 A and  14 B has a shape, for example, such that one of the two main opposite surfaces of each lead terminal is partially exposed from the surface  11   b  defining the bottom of the recess  11 , and the other main surface is partially exposed from the lower surface  10   b  of the package  10 . The package  10  may be provided with an electrode or interconnect formed on a surface of the base body  13 , instead of the lead terminals  14 A and  14 B. 
     For the lead terminals  14 A and  14 B a material having a relatively high thermal conductivity is preferably used. Using such a material for the lead terminal allows for efficiently transferring and dissipating heat generated in the light-emitting element  20  to the outside of the package  10 . For example, a material having a thermal conductivity of about 200 W/(m·K) or more is preferably used. Furthermore, a material having a relatively high mechanical strength is preferably used. Examples of the lead terminal include a metal plate of aluminum, iron, nickel, copper, an alloy thereof or the like that has been processed to have a desired shape by pressing such as punching or the like, etching, or the like. Furthermore, a surface of the lead terminals  14 A and  14 B is preferably coated with a metal film. For the metal film, for example, Ag, an Ag alloy, Au, an Au alloy, or the like can be preferably used. In addition, a layer containing Ni is preferably disposed to serve as an underlying layer for the metal film. Examples of the underlying layer include a layered structure containing Ni/Pd, Ni/Au, Ni/Pd/Au, or the like. The metal film may be formed by, for example, a plating. With the lead terminal having such a metal film can be more easily joined to the light reflective member  15  and/or a conductive wire to be described below or the like. The lead terminal has a thickness of, for example, in a range of 110 to 250 μm. The lead terminal may have different thicknesses at different portions due to the processing described above or the like. In the case in which a plating is formed on a surface of the lead terminal, the plating may have different thicknesses or different layer structures at different portions. 
     Light Reflective Member  15   
     The light-emitting device  101  may include the light reflective member  15 . The light reflective member  15  reflects light emitted from the light-emitting element  20  toward the opening  11   a . The light reflective member  15  is disposed in the recess  11 , covering the inner lateral surface  11   c  defining the recess  11  and at least a portion of the surface  11   b . The light reflective member  15  is preferably spaced apart from the lateral surface of the light-emitting element  20  so as not to hinder extraction of light from the lateral surface of the light-emitting element  20 . 
     The light reflective member  15  has a sloped surface  15   s . The sloped surface  15   s  has a height gradually reduced from the inner lateral surface  11   c  defining the recess  11  toward the light-emitting element  20 . As a result, the sloped surface  15   s  has a curved surface that is convex toward the inner surface  11   c  and the surface  11   b  defining the bottom of the recess  11 . This allows the light reflective member  15  to reflect light emitted from the light-emitting element  20  toward the opening  11   a , and therefore, the external extraction efficiency of the light-emitting device  101  can be increased. 
     For the light reflective member  15 , a member that does not easily transmit or absorb light from the light-emitting element  20  or external light, etc is preferably used. The light reflective member  15  preferably has a white color. Examples of a resin serving as a base material for the light reflective member  15  include a thermosetting resin, thermoplastic resin, and the like. More specifically, a phenolic resin, epoxy resin, BT resin, PPA, silicone resin, etc., can be used. When light-scattering particles of a light reflective substance that does not easily absorb light from the light-emitting element and has a refractive index very different from that of the resin as the base material (e.g., titanium oxide, zinc oxide, silicon oxide, zirconium oxide, aluminum oxide, or aluminum nitride) are dispersed in these resins serving as the base material, light can be efficiently reflected. The viscosity of the light reflective member  15  in the uncured state is preferably lower than the viscosity of the sealing member  30  in the uncured state. For example, the viscosity of the light reflective member  15  in the uncured state is preferably in a range of 1 to 20 pa·s, more preferably 5 to 15 pa·s. This allows for facilitating wet-spread of the light reflective member  15  in the recess  11 , and allows for reducing possibility that the amount of the light reflective member  15  provided in the recess  11  is insufficient. The light reflective member  15  in the uncured state preferably has high thixotropy. The light reflective member  15  preferably has a light reflectance higher than that of the base body  13 . 
     Light-Emitting Element  20   
     The light-emitting element  20  is a semiconductor light-emitting element, such as a semiconductor laser or light-emitting diode. The light-emitting element  20  may have any appropriate emission wavelength. For example, for a blue or green light-emitting element, a light-emitting element employing ZnSe or a nitride semiconductor (In X Al Y Ga 1-X-Y N, 0≤X, 0≤Y, and X+Y≤1) can be used. For a red light-emitting element, a GaAs, AlInGaP, or AlGaAs semiconductor, etc., can be used. In addition, a semiconductor light-emitting element formed of other materials can be used. The composition, emission color, size, number, etc., of a light-emitting element(s) used can be appropriately selected according to the purpose. Not only a light-emitting element configured to emit visible light but also a light emitting element configured to emit ultraviolet or infrared light can be used. 
     As described below, the sealing member  30  may include a wavelength conversion member. When the sealing member  30  includes a wavelength conversion member, an entirety or a portion of light emitted from the light-emitting element  20  can be converted into light in another wavelength band. In that case, the light-emitting device  101  emits a mixture of light emitted from the light-emitting element  20  and light emitted from the wavelength conversion member, or alternatively, only light emitted from the wavelength conversion member. For example, when the light-emitting element  20  emits blue light, and the wavelength conversion member converts blue light into yellow light, the light-emitting device  101  can be configured to emit white light in which blue light emitted from the light-emitting element  20  and yellow light emitted from the wavelength conversion member is mixed. Alternatively, for example, when the light-emitting element  20  emits blue light, and the wavelength conversion member converts blue light into red light or pale yellow light, causing light emitted from the wavelength conversion member to be emitted from the light-emitting device  101  allows the light-emitting device  101  to emit red light or pale yellow light. In this embodiment, the light-emitting device  101  includes a single light-emitting element. Alternatively, the light-emitting device  101  may include a plurality of light-emitting elements. In the case in which the light-emitting device  101  includes a plurality of light-emitting elements, the plurality of light-emitting elements may emit similar colors or different colors. For example, the light-emitting device  101  may include three light-emitting elements that emit red light, blue light, and green light, which allows the light-emitting device  101  to emit full-color light. 
     In this embodiment, the light-emitting element  20  is disposed on the lead terminal  14 A exposed from the surface  11   b  defining the bottom of the recess  11 . The at least one pair of positive and negative electrodes of the light-emitting element  20  are electrically connected to the lead terminals  14 A and  14 B exposed from the surface  11   b  defining the bottom of the recess  11  through conductive wires  21 A and  21 B, respectively. In the light-emitting device  101  of this embodiment, the light-emitting element  20  is offset from a center  11   f  of the surface  11   b  defining the bottom of the recess  11  and is located closer to the inner surface in a plan view. In other words, the center of the light-emitting element  20  does not coincide with the center  11   f  of the surface  11   b  defining the bottom of the recess  11 . With the light-emitting element  20  located closer to the inner lateral surface than the center  11   f  of the surface  11   b  defining the bottom of the recess  11 , while the size of the light-emitting device  101  can be reduced, a connecting area of a wire-bond connecting the light-emitting element  20  and the lead terminal, and a mount area of electronic components, such as a protective element, can be ensured. 
     Protective Element  40   
     The light-emitting device  101  may include, in addition to the light-emitting element  20 , electronic components, such as a protective element. In this embodiment, the light-emitting device  101  includes a protective element  40 . Examples of the protective element  40  include a Zener diode, which prevents breakage of the light-emitting element  20  due to static electricity, etc. 
     The protective element  40  has an electrode on each of the upper and lower surfaces of the protective element  40 , and the lower surface is electrically connected to a corresponding one of the lead terminal  14 A and  14 B through a conductive bonding member, such as solder, so that the electrode on the lower surface is electrically coupled to the corresponding one of the lead terminal  14 A or  14 B. In this embodiment, the protective element  40  is disposed on the lead terminal  14 B exposed at the surface  11   b  defining the bottom of the recess  11 , and the electrode on the lower surface thereof is electrically connected to the lead terminal  14 B. The electrode on the upper surface of the protective element  40  is electrically connected to the lead terminal  14 A through a conductive wire  22 A. By such wiring, the light-emitting element  20  and the protective element  40  are connected together in parallel. 
     Sealing Member  30   
     The sealing member  30  is disposed in the recess  11  to protect the light-emitting element  20 , the conductive wires  21 A,  21 B, and  22 A, the protective element  40 , etc., from moisture, external force, and dust. The sealing member  30  is disposed in the recess  11 , and covers the light-emitting element  20 , the protective element  40 , and the conductive wires  21 A,  21 B, and  22 A in the recess  11 . The sealing member  30  is not disposed on the upper surface  10   a  of the package  10 . 
     The sealing member  30  has an upper surface  30   a , which is a boundary between the light emission surface of the light-emitting device  101  and the outside. The upper surface  30   a  has a flat region Rp, and a sloped region Rs, which is continuous to the flat region Rp and extends to an end portion of the opening of the recess  11  of the package  10 . The flat region Rp includes a region Rd located above the light-emitting element  20  and including a region directly above the light-emitting element  20 . The entirety of the flat region Rp is substantially parallel to a reference surface of the package  10 . As used herein, the expression “substantially parallel” refers to a case in which an angle with respect to a surface of the package  10  that serves as a reference surface for parallel configuration is in the range of ±3°. The “reference surface of the package  10 ” refers to, for example, the upper surface  10   a , the surface  11   b , etc. 
     The sloped region Rs surrounds the flat region Rp, and is continuous to the flat region Rp. The sloped region Rs extends to the end portion of the opening  11   a  located in the upper surface  10   a  of the package  10 . In other words, the sloped region Rs is located between the flat region Rp and the end portion of the opening  11   a , and the sloped region Rs surrounds the flat region Rp, and the end portion of the opening  11   a  surrounds the sloped region Rs. The sloped region Rs is a portion of the upper surface  10   a  that is sloped at an angle of more than ±3° with respect to a horizontal reference surface of the package  10 . 
     The size of the flat region Rp is preferably 80% or more of the area of the entirety of the upper surface  30   a  of the sealing member  30  in a plan view. The size of the flat region Rp is more preferably 85% or more, even more preferably 90% or more, of the area of the entirety of the upper surface  30   a . Meanwhile, the upper limit of the size of the flat region Rp is not particularly limited. For example, the flat region Rp may occupy the entire upper surface  30   a . However, as described below, it is not preferable for an uncured sealing member to overflow from the recess  11  during manufacturing of the light-emitting device  101 . Therefore, in order that the upper surface of an uncured sealing member disposed in the recess  11  is located lower than the upper surface  10   a  of the package  10 , the amount of the uncured sealing member disposed in the recess  11  is set to be smaller than the capacity of the recess  11 . This allows the flat region Rp of the upper surface  30   a  of the sealing member  30  to be located below the upper surface  10   a  of the package  10 , resulting in generation of the sloped region Rs surrounding the flat region Rp. The sloped region Rs surrounding the flat region Rp has a width in a range of, for example, 0.01 to 0.60 mm in a plan view. Considering the physical properties of a sealing member used and the upper surface area and mount position of the light-emitting element  20 , the size of the flat region Rp is determined so that at least the upper surface of the light-emitting element  20  is located directly below the flat region Rp. 
     As described in detail below, in conventional light-emitting devices, almost no flat region is formed in the upper surface of the sealing member, or the proportion of the flat region to the upper surface is small. According to the light-emitting device of the present disclosure, a large flat region Rp can be formed in the upper surface  30   a  by curing the sealing member  30  while applying a centrifugal force. With the sealing member  30  including the above flat region Rp in the upper surface  30   a , it is possible to reduce the occurrence of unevenness in chromaticity of emitted light, e.g., unevenness in emission color between a region at and near the center and a region at and near the outer periphery of light emitted from the light-emitting device  101  in the case in which the sealing member  30  includes a wavelength conversion member. Reduction in unevenness in chromaticity of emitted light allows for reducing the amount of the light reflective member that is added to the sealing member  30  in order to mix the colors of light, compared to when a great unevenness in chromaticity of emitted light occurs (e.g., the case in which the sealing member  30  does not include the flat region Rp), resulting in increase in light extraction efficiency. 
     The sealing member  30  is preferably light-transmissive to light emitted from the light-emitting element  20 . More specifically, the sealing member  30  preferably contains a silicone resin as the base material  31 . Examples of the silicone resin include dimethyl silicone resins, methyl phenylsilicone resins, and phenylsilicone resins. Silicone resins has good resistance to heat and light, and therefore, are preferably used for the base material  31  of the sealing member  30 . Alternatively, an epoxy resin may be used for the base material  31 . While epoxy resins are generally known as resins having a relatively great reduction in volume when cured, curing the epoxy resin while applying a centrifugal force thereto allows for obtaining the sealing member  30  having a flat upper surface  30   a.    
     The sealing member  30  may contain a filler in addition to the base material  31 . In this embodiment, the sealing member  30  may contain a wavelength conversion member  32  that serves as a filler. Examples of the wavelength conversion member  32  include a phosphor, quantum dot, or the like. For the phosphor, a known phosphor can be employed. Examples of the phosphor include yttrium aluminum garnet (YAG) activated by cerium, lutetium aluminum garnet (LAG) activated by cerium, and nitrogen-containing aluminosilicate calcium (CASN) activated by europium and/or chromium. For the phosphor, a combination of a plurality of kinds of phosphors may be employed. For example, a combination of phosphors having different emission colors that is suitable for a desired color, or a mixture of phosphors having different emission colors at a mixing ratio suitable for a desired color, can be used to adjust color rendering or color reproducibility. 
     As described above, in the light-emitting device  101  according to the present disclosure, the upper surface of the sealing member includes a large flat region, resulting in reduction of luminance unevenness and unevenness in chromaticity of light emitted from the light-emitting device  101 , which is one object of the present disclosure. Accordingly, the amount of a light reflective member added in order to reduce unevenness in luminance and unevenness in chromaticity of emitted light can be reduced compared to the amount of a light reflective member added in order to reduce unevenness in luminance and unevenness in chromaticity of light emitted from a light-emitting device that does not have a large flat region, resulting in an improvement in light extraction efficiency of a light-emitting device. 
     The sealing member  30  may contain a light reflective member serving as a filler. Examples of the light reflective member include silicon oxide (silica), titanium oxide, magnesium oxide, zirconium oxide, titanate barium, and aluminum oxide. When the light reflective member is irradiated with light emitted from the light-emitting element  20  or light emitted from the wavelength conversion member  32 , the light reflective member reflects the light in random directions, and therefore, the unevenness in luminance, unevenness in emission color, etc., of light emitted from the light-emitting device  101  can be further reduced. 
     The sealing member  30  may contain, as a filler, a light absorbing substance to the extent that light-transmissiveness of the sealing member  30  is not impaired. The light absorbing substance may be a black pigment, such as carbon black or graphite. With such a filler dispersed in the sealing member  30 , the unevenness in emission color of the light-emitting device  101  can be reduced, and the decrease of display contrast of the light-emitting device  101  can be reduced, for example. 
     The sealing member  30  may not contain any one of the fillers described above, or may contain one or more of the fillers described above. In the case in which the particles of the filler are spherical, the filler particles easily sediment in the base material  31  in the uncured state. Therefore, light emitted from the light-emitting element  20  is likely to be emitted to the outside without being scattered at or near the upper surface  30   a  of the sealing member  30 . Therefore, the efficiency of extraction of light from the sealing member  30  can be improved. 
     The fluorescent characteristics of the phosphor used for the wavelength conversion member  32  may decrease due to moisture in an external environment, etc., depending on compositions of constituent elements of the phosphor. In the case in which the sealing member  30  contains a phosphor having such characteristics, in the sealing member  30 , the phosphor can be predominantly distributed at the surface  11   b  side of the recess  11  utilizing a centrifugal force as described below. Accordingly, the phosphor can be disposed further inward away from the upper surface  30   a  of the sealing member  30 , which is a boundary with an external environment, to the extent possible. Therefore, the degradation of the phosphor due to moisture in an external environment can be reduced. 
     Meanwhile, in the case in which the filler particle has a crushed form, the filler particle has a surface area larger than that of a spherical particle having a similar size. Therefore, the sedimentation of such filler particles in the base material  31  in the uncured state is reduced even in the state in which centrifugal force is applied. In particular, in the case in which the filler particle has a small particle size, the filler particle is less affected by a centrifugal force. Accordingly, the filler can be located closer to the upper surface  30   a  of the sealing member  30 . 
     Therefore, when the sealing member  30  contains a plurality of kinds of fillers, utilizing difference in shape of particles, one filler can be uniformly distributed in the sealing member  30  while another filler can be distributed predominantly at the surface  11   b  side of the recess  11 , even in the state where a centrifugal force is applied. 
     Light Emission of Light-Emitting Device  101   
     Configuration that allows reduction in unevenness in chromaticity of light emitted from the light-emitting device  101  will be described below. As described above, in the light-emitting device  101 , the upper surface  30   a  of the sealing member  30  includes the large flat region Rp. The sealing member  30  having such a structure is formed utilizing a centrifugal force. 
       FIG. 3A  schematically shows a cross-sectional structure of a conventional light-emitting device  151 .  FIG. 3B  is an enlarged view of a portion of the structure of  FIG. 3A . When a sealing member  130  is formed in a recess  11  of a package  10  in the conventional light-emitting device  151 , an uncured sealing member is disposed in the recess  11  by potting or the like, and thermal treatment or the like is performed to cure the uncured sealing member, so that the sealing member  130  is obtained. At this time, the volume of the sealing member  130  decreases (which may also be referred to as shrinkage of the sealing member  130 ) due to the thermal curing of the uncured sealing member. Accordingly, the upper surface  130   a  of the cured sealing member  130  has a height smallest at the center  11   f  of the recess  11  of the light-emitting device  151  in a plan view, and forms, as a whole, a sloped region having an angle that is gradually increased in an outward direction from the center  11   f . Therefore, in the conventional light-emitting device  151 , almost no flat region is formed in the upper surface  130   a  of the sealing member  130 . 
       FIG. 3C  is a schematic diagram for describing light emitted from a portion of the flat region Rp of the upper surface  30   a  of the sealing member  30  in the light-emitting device  101 , the portion located at a peripheral side with respect to a portion directly above the light-emitting element  20 .  FIG. 3D  is a schematic diagram for describing light emitted from a region R 151  of the sloped region Rs of the upper surface  130   a  of the sealing member  130  in the conventional light-emitting device  151 , the region R 151  located at a peripheral side with respect to a portion located directly above the light-emitting element  20 . In the light-emitting device  101 , the upper surface  30   a  in the flat region Rp is parallel to the surface  11   b  defining the bottom of the recess  11 . In contrast to this, in the conventional light-emitting device  151 , the upper surface  130   a  has a slope with a height smallest at the center  11   f  and gradually increased toward the periphery of the upper surface  130   a.    
     For each of the upper surfaces  30   a  and  130   a , light L 1  that is emitted directly from the light-emitting element  20  and light L 2  that travels in the recess  11  and reflected at the sloped surface of the light reflective member  15  to travel toward the upper surface  30   a ,  130   a  will be discussed below. The angles of incidence of the light L 1  and L 2  entering the upper surface  30   a  with reference to a line (indicated by a dashed line) perpendicular to the upper surface  30   a , are represented by θ 1   a  and θ 1   b , respectively. The angles of incidence of the light L 1  and L 2  entering the upper surface  130   a  with reference to a line (indicated by a dashed line) perpendicular to the upper surface  130   a , are represented by θ 2   a  and θ 2   b , respectively. 
     In  FIGS. 3C and 3D , light L 1  travels in a direction at the same angle. Likewise, in  FIGS. 3C and 3D , light L 2  travels in a direction at the same angle. In this case, due to slope of the upper surface  130   a , θ 1   a &lt;θ 1   b  and θ 2   a &gt;θ 2   b  are satisfied. In other words, incident angle of light L 1  is greater in the conventional light-emitting device  151 , and therefore, total internal reflection is more likely to occur in the conventional light-emitting device  151 . Therefore, light L 1  is relatively more easily emitted from the light-emitting device  101 , and is relatively less easily emitted from the light-emitting device  151 . Meanwhile, incident angle of light L 2  is greater in the light-emitting device  101  according to one embodiment of the present disclosure, and therefore, total internal reflection is more likely to occur in the light-emitting device  101  according to one embodiment of the present disclosure. Therefore, light L 2  is relatively less easily emitted from the light-emitting device  101 , and is relatively more easily emitted from the light-emitting device  151 . 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Light L1 
                 Light L2 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Light-emitting 
                 More easily 
                 Less easily 
               
               
                   
                 device 101 
                 emitted 
                 emitted 
               
               
                   
                 Conventional 
                 Less easily 
                 More easily 
               
               
                   
                 light-emitting 
                 emitted 
                 emitted 
               
               
                   
                 device 151 
               
               
                   
                   
               
            
           
         
       
     
     A case is considered in which the light-emitting element  20  emits blue light and the sealing members  30  and  130  contain a yellow phosphor in the light-emitting device  101  and the conventional light-emitting device  151 , causing emission of white light from the light-emitting devices  101  and  151  in the light-emitting device  101  and the conventional light-emitting device  151 . In this case, light L 1  is mainly blue light, and light L 2  is transmitted in the sealing members  30  and  130 , and accordingly contains a greater amount of yellow light excited by the phosphor. Therefore, it is considered that, in the conventional light-emitting device  151 , light L 2  is relatively more easily emitted, and therefore, chromaticity deviation occurs particularly at a periphery of the upper surface  130   a  where the upper surface  130   a  is more sloped, so that yellow light is noticeable at a peripheral portion with respect to the optical axis of light emitted from the light-emitting device  151 . 
     In contrast to this, in the light-emitting device  101 , light L 2  is less likely to be emitted, and therefore, chromaticity deviation toward yellow can be reduced. In addition, the area of the sloped region of the upper surface  30   a  is small, and therefore, the region where chromaticity deviation occurs can be reduced. Therefore, according to the present disclosure, a light-emitting device with reduction in unevenness in emission color can be obtained. 
     Further, controlling the shape of the upper surface  30   a  of the sealing member  30  allows for reducing unevenness in emission color. Therefore, the amount of a light reflective member that is added to the sealing member in order to reduce unevenness in emission color can be reduced, or the sealing member  30  that does not contain a light reflective member can be used. Accordingly, the amount of light emitted from the sealing member  30  can be increased. In addition, the fluidity of the uncured sealing member can be increased by reducing the amount of a light reflective member, so that the uncured sealing member can be more easily disposed in the recess  11 . 
     Thus, in the light-emitting device  101 , the upper surface  30   a  of the sealing member  30  has a substantially flat region including at least a region directly above the light-emitting element. Therefore, in at least a region directly above the light-emitting element, light traveling toward outside of the sealing member  30  at the same angle is incident on the interface between the upper surface  30   a  and the outside at the same incident angle, irrespective of a location at which light is emitted out of the sealing member  30 , and therefore, deviation in chromaticity of emitted light can be reduced. Such an optical relationship is maintained, particularly even when the light-emitting element  20  is located offset from the center of the recess  11 . Therefore, even in a light-emitting device in which the light-emitting element is not disposed at the center thereof, deviation in chromaticity can be reduced. 
     The greater such a flat region of the upper surface of the sealing member, the greater the light distribution angle that allows for reducing unevenness in chromaticity of emitted light, and accordingly, the more greatly unevenness in chromaticity of a light-emitting device can be reduced. 
     Method of Producing Light-Emitting Device 
     Next, a method of producing the light-emitting device  101  will be described.  FIG. 4  is a flowchart showing production steps in the method of producing the light-emitting device of the present disclosure.  FIGS. 5A-5E and 6A  are schematic cross-sectional views for describing steps of the method of producing the light-emitting device.  FIGS. 6B-6D  are schematic plan views for describing the method of producing the light-emitting device. 
     The method of producing the light-emitting device of the present disclosure includes (A) a step of preparing a package, (B) a step of disposing a light-emitting element in the package, (D) a step of filling the package with an uncured sealing member, and (E) curing the uncured sealing member while applying a centrifugal force. In the case in which the light-emitting device  101  includes the light reflective member  15 , the method of producing the light-emitting device of the present disclosure includes, between the steps (B) and (D), (C) a step of forming the light reflective member  15 . These steps will now be described in detail. 
     (A): Providing Package (S 1 ) 
     As shown in  FIG. 5A , a package  10  is provided that includes an upper surface  10   a , and defining a recess  11  having an opening  11   a  in the upper surface  10   a . As described above, the package  10  includes lead terminals  14 A and  14 B and a base body  13 . The method of producing the light-emitting device of the present disclosure can be used to produce a single light-emitting device  101 , or a plurality of light-emitting devices  101  at once. In the case in which a plurality of light-emitting devices  101  are produced at once, a plurality of packages  10  are provided. In order to increase manufacturing efficiency when mounting the light-emitting element  20  and when disposing the sealing member  30 , etc., a plurality of packages  10  are preferably arranged on the same plane at a predetermined pitch. For example, as shown in  FIG. 6A , a support substrate  300  is prepared, and a plurality of packages  10  are disposed on an upper surface of the support substrate  300  at a predetermined pitch such that the lower surface  10   b  of each package  10  is bonded to the upper surface of the support substrate  300 . 
     Alternatively, as shown in  FIG. 6C , a resin-molded lead frame  200 , in which a plurality of packages  10  are integrally disposed, may be provided. The resin-molded lead frame  200  includes a lead frame  210  and an insulating member  220 . As shown in  FIGS. 6B and 6C , the lead frame  210  includes a plurality of package regions arranged in an x-direction and a y-direction which are orthogonal to each other. Each package region includes lead terminals  14 A and  14 B. In each package region, the lead terminals  14 A and  14 B are spaced apart from each other, and the lead terminal  14 B is connected via a connection portion  211  to the lead terminal  14 A in another package region adjacent thereto in the x-direction. The lead terminals  14 A and  14 B are also connected to the lead terminals  14 A and  14 B disposed in another package region adjacent thereto in the y-direction, by connection portions  212 A and  212 B. 
     The resin-molded lead frame  200  includes the lead frame  210  and the insulating member  220 . The resin-molded lead frame  200  has a plurality of recesses  11  corresponding to the respective package regions, at an upper surface thereof. A portion of each of the lead terminals  14 A and  14 B is exposed from the bottom surface of the recess  11 . 
     The resin-molded lead frame  200  is formed using the lead frame  210 , and an insulating material that is to be the base body  13 . The base body  13  can be molded by performing insert molding or the like. 
     Thus, using a lead frame having a resin in which a plurality of packages are connected together in the step (A) of providing a package allows the step (B) of disposing a light-emitting element in the package and step (D) of disposing an uncured sealing member, which are subsequent to the step (A), to be performed with respect to the plurality of packages, and allows the step (E) of curing the uncured sealing member while applying a centrifugal force to be performed with respect to each lead frame. 
     (B): Disposing Light-Emitting Element in Package (S 2 ) 
     As shown in  FIG. 5B , a light-emitting element  20  is disposed on the surface  11   b  defining the bottom of the recess  11  of the package  10 . The light-emitting element  20  is provided, and is connected to the surface  11   b  defining the bottom of the recess  11  using an adhesive member. In this embodiment, the light-emitting element  20  is bonded to an upper surface of the lead terminal  14 A. Likewise, a protective element  40  is bonded to an upper surface of the lead terminal  14 B. Next, a pair of electrodes of the light-emitting element  20  are connected to the lead terminals  14 A and  14 B by conductive wires  21 A and  21 B, respectively. Likewise, an electrode of the protective element  40  is coupled to the lead terminal  14 A by a conductive wire  22 A. 
     (C): Disposing Light Reflective Member (S 3 ) 
     In the case in which the light-emitting device  101  includes a light reflective member  15 , a step of disposing the light reflective member  15  is preferably performed after the light-emitting element  20  is disposed. As shown in  FIG. 5C , in the step of disposing the light reflective member  15 , the light reflective member  15  is disposed in the recess  11  so as to cover the bottom surface of the recess  11  and inner lateral surface defining the recess  11 . The light reflective member  15  is formed as described below. A light reflective substance is added to and dispersed in an uncured resin serving as a base material of the light reflective member  15 , to prepare an uncured light reflective member  15 ′. Next, the uncured light reflective member  15 ′ is disposed on the bottom surface of the recess  11  in a region between the light-emitting element  20  and the inner lateral surface  11   c  defining the recess  11 . As a result, the uncured light reflective member  15 ′ is spread to cover a portion of the surface  11   b  defining the bottom of the recess  11  and the inner lateral surface  11   c  defining the recess  11 . At this time, an entirety or a portion of the protective element  40  and an entirety or a portion of the conductive wire  22 A may be covered by the uncured light reflective member  15 ′. Thereafter, the uncured light reflective member  15 ′ is cured by heating or the like. Thus, the light reflective member  15  is formed. 
     (D): Disposing Uncured Sealing Member (S 4 ) 
     As shown in  FIG. 5D , an uncured sealing member containing a silicone resin is disposed in the recess  11  of the package  10 . An uncured sealing member  30 ′ is prepared. For the uncured sealing member  30 ′, an uncured silicone resin in which a wavelength conversion member  32  is added and dispersed is prepared. The uncured sealing member  30 ′ thus prepared is disposed in the recess  11  of the package  10  using a dispenser or the like. At this time, the uncured sealing member  30 ′ is disposed such that the uncured sealing member  30 ′ does not overflow from the opening  11   a  of the upper surface  10   a  of the package  10  and does not cover the upper surface  10   a . The uncured sealing member  30 ′ preferably covers an entirety of the light-emitting element  20 , an entirety of the protective element  40 , and an entirety of the conductive wires  21 A,  21 B, and  22 A, which are located in the recess  11 . In consideration of resin overflow during potting, the uncured sealing member  30 ′ is preferably disposed in the recess  11  of the package  10  such that the upper surface of the uncured sealing member  30 ′ is located lower than the upper surface  10   a  of the package  10 . If the upper surface  10   a  is flush with the upper surface of the uncured sealing member  30 ′, the uncured sealing member  30 ′ is likely to be spread onto the upper surface  10   a  before a centrifugal force is applied in the next step. 
     (E): Curing Uncured Sealing Member while Applying Centrifugal Force (S 5 ) 
     The uncured sealing member  30 ′ disposed in the recess  11  of the package is cured while a centrifugal force is applied to the package in a direction perpendicular to the upper surface and toward the surface  11   b  defining the bottom of the recess  11 . As shown in  FIG. 7A , an oven  500  including a rotation mechanism configured to hold and rotate the package  10  to apply a centrifugal force to the package  10  is provided. The oven  500  includes a rotation mechanism  510  having an arm  511 . The arm  511  is, for example, configured to be rotated around the center of the arm  511  in the longitudinal direction. Support frames  512  are attached to both ends of the arm  511 . Each support frame  512  is provided with a support portion  513 , which is configured to support the support substrate  300  on which a plurality of packages  10  are disposed or the resin-molded lead frame  200 . The support frames  512 , at both ends of the arm  511 , are configured to rotate around an axis  511   a  located in a plane perpendicular to an axis  510   a  of rotation of the rotation mechanism  510  and parallel to a tangential direction of a circle having the axis  510   a  of rotation as the center of the circle. 
     The support substrate  300  or the resin-molded lead frame  200  that has been subjected to the steps (A) to (D) is placed on the support portion  513  of the support frame  512 , and the rotation mechanism  510  is driven to rotate the arm  511 . Accordingly, as shown in  FIG. 7B , the support frame  512  experiences a centrifugal force, so that the support frame  512  is rotated around the axis  511   a  such that the support portion  513  becomes parallel to the axis  510   a  of rotation. As a result, as shown in  FIG. 5D , the uncured sealing member  30 ′ experiences a centrifugal force F in a direction perpendicular to the upper surface  10   a  of the package  10  and toward the surface  11   b  defining the bottom of the recess  11 . In this state, the centrifugal force caused by the rotation does not act on the package  10  in a direction parallel to the upper surface  10   a  of the package  10 , i.e., a direction parallel to the axis  511   a.    
     The magnitude of the centrifugal force F is preferably 100 G (×g) or more in terms of relative centrifugal force (RCF). The centrifugal force F is sufficiently greater than the centrifugal force that allows a wavelength conversion member to sediment when the uncured sealing member  30 ′ contains the wavelength conversion member. The magnitude of the centrifugal force F, which varies depending on the type of the base material of the sealing member, the size of the recess  11 , etc., is preferably 200 G or more, more preferably 300 G or more. The upper limit of the centrifugal force F is not particularly limited. However, if the centrifugal force F is excessively great, the structures formed through the steps (A)(D), such as the conductive wires  21 A,  21 B, and  22 A formed in the recess  11 , may be deformed. Also, in the case in which the sealing member  30  contains an additive material in addition to the wavelength conversion member, the additive material may not be distributed in the sealing member  30  as intended. Therefore, the centrifugal force F is preferably, for example, 500 G or less. 
     As shown in  FIG. 7C , while the centrifugal force F is applied to the package  10 , the support portion  513  may be allowed to be deformed so that a portion at and near the center of the support portion  513  of the support frame  512  is located further away from the center of rotation in a plane perpendicular to the axis  510   a  of rotation. This causes the support substrate  300  or the resin-molded lead frame  200  to be deformed into an arc shape in a plane perpendicular to the axis  510   a  of rotation, and the opposite ends of the support portion  513  are directed in the tangential direction. Accordingly, an entirety of the packages  10  on each support substrate  300  or the resin-molded lead frame  200  supported by the support portion  513  can more uniformly experience the centrifugal force F in a direction perpendicular to the upper surface  10   a  of the package  10 . 
     As shown in  FIG. 5E , by applying the centrifugal force F, the upper surface  30   a ′ of the uncured sealing member  30 ′ can be maintained horizontal. By curing the uncured sealing member  30 ′ in such a state, a large flat region Rp can be formed in the upper surface  30   a ′. Further, creep-up of the uncured sealing member  30 ′ onto the upper surface  10   a  of the package  10  due to surface tension or the like can also be reduced. 
     In the case in which the uncured sealing member  30 ′ contains the wavelength conversion member  32 , such as a phosphor, the wavelength conversion member  32  is sedimented by the centrifugal force F, and is distributed predominantly at the surface  11   b  side of the recess  11 . 
     As described above, the uncured sealing member  30 ′ is cured in the presence of an applied centrifugal force. In the case in which a thermosetting resin is used for a base material of the sealing member  30 ′, the uncured sealing member  30 ′ can be cured by maintaining the package  10  at a temperature equal to or higher than a temperature that allows the uncured sealing member  30 ′ to be cured, while applying a centrifugal force to the package  10 . More specifically, the package  10  is heated in the oven  500  such that the temperature in the cavity of the oven  500  is maintained at a temperature, for example, equal to or higher than a temperature that allows a silicone resin to be cured. The temperature is maintained at, for example, 50° C. or higher. The temperature may be maintained for, for example, 0.5 to 4.0 hours. 
     When the uncured sealing member  30 ′ begins to be cured, for example, a portion at and near the center of the upper surface  30   a ′ may become recessed due to the shrinkage of the uncured sealing member  30 ′. However, due to application of the centrifugal force F, a portion of the uncured sealing member  30 ′ is slightly moved in the recess  11  so that the entire upper surface  30   a ′ becomes horizontal. Accordingly, the uncured sealing member  30 ′ is cured with a large flat region Rp maintained, so that a sealing member  30  having an upper surface  30   a  including the large flat region Rp is disposed in the recess  11 . This allows for obtaining a light-emitting device  101  in which the overflow of the sealing member  30  onto the upper surface is reduced. When the light-emitting devices  101  are produced for each resin-molded lead frame  200 , i.e., on a lead frame-by-lead frame basis, separating into individual packages is performed subsequently. 
     In the case in which a UV-curable resin is used for a base material of the sealing member  30 ′, the sealing member  30 ′ is cured by irradiation with UV light in the presence of an applied centrifugal force. Alternatively, in the case in which a material that can be cured at room temperature is used for the base material, the sealing member  30 ′ is cured at room temperature while a centrifugal force is applied thereto, so that a sealing member  30  having an upper surface  30   a  including the large flat region Rp is disposed in the recess  11 . 
     (F) Separating into Individual Packages (S 6 ) 
     The resin-molded lead frame  200  in which the sealing member  30  is disposed in the recess  11  of each package  10  is separated into the individual packages  10  by cutting the insulating member  220  and the connection portions  211 ,  212 A, and  212 B. Specifically, as indicated by dashed lines in  FIG. 6D , separation into the individual packages  10  are performed by cutting the insulating member  220  and the connection portions  211 ,  212 A, and  212 B at boundaries between each package  10 , using a blade or the like. As a result, the light-emitting device  101  is obtained. The separation into individual packages  10  can be performed using other known techniques, such as laser processing. 
     Examples 
     A light-emitting device according to one embodiment was produced, and the light distribution angle dependency of chromaticity of light emitted from the light-emitting device was investigated. A result of the investigation will be described below.  FIG. 8  is a diagram showing deviations of a chromaticity coordinate y depending on a directional angle in the light-emitting device  101  (Example 1) that was produced according to the method of producing the light-emitting device of the embodiment described above. In  FIG. 8 , the horizontal axis represents a light distribution angle, and the vertical axis represents a deviation of the y-value in a CIE chromaticity diagram, where 0° is a reference. Reference Example 1 indicates the result of measurement of a light-emitting device that was produced in a manner in which a centrifugal force was applied to a package according to the step (E) and thereafter the rotation of the rotation mechanism  510  was stopped, and then the uncured sealing member  30 ′ was cured without applying a centrifugal force. Reference Example 2 indicates the result of measurement of a light-emitting device that was produced according to a conventional method of producing in which a centrifugal force was not applied to a package. 
     As shown in  FIG. 8 , in Example 1, Δy is negative when the absolute value of the light distribution angle is greater than 0°, while the value of Δy is generally constant in a range in which the absolute value of the light distribution angle is in the range of 30-80°. In contrast to this, in Reference Example 2, as the absolute value of the light distribution angle increases from 0°, the value of Δy changes from negative to positive, i.e., greatly changes. In particular, Δy increases in the case in which the absolute value of the light distribution angle is in the range of greater than 60°. These results shows that, according to the light-emitting device of one embodiment, deviation in chromaticity is reduced particularly in a region with a greater light distribution angle. 
     Further, in the light-emitting device of Reference Example 1, while light distribution angle dependency of chromaticity similar to that of the light-emitting device of Reference Example 2 was observed chromaticity deviation was reduced to some degree. 
     The light-emitting device of the present disclosure can be preferably used in various applications, such as luminaire applications, in-vehicle applications, display devices, and electronic devices. 
     While certain embodiments of the present invention have been described above, it will be apparent to those skilled in the art that the disclosed invention may be modified in numerous ways and may assume many embodiments other than those specifically described above. Accordingly, it is intended for the appended claims to cover all modifications of the invention that fall within the true spirit and scope of the invention.