JP6048001B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device, and more particularly to a light emitting device including a joining member that joins a light emitting element to a mounting member.

  For example, as described in Patent Documents 1 and 2, conventionally, as a bonding material for bonding a semiconductor element to a wiring board or a lead frame, a sintered paste in which metal particles such as silver are dispersed in an organic solvent (hereinafter, referred to as a bonding material) (Referred to as “metal particle sintered paste”).

  The metal particle sintered paste can be bonded by heating the temperature around 200 ° C. to volatilize the organic solvent and sinter the metal particles. In addition, the theoretical heat limit after the bonding is the melting point of the metal particles (for example, about 962 ° C. for silver). For this reason, the metal particle sintered paste is generally superior in bonding temperature and heat resistance compared to lead-free eutectic solder that has a melting point of 300 ° C. or higher and remelts at a temperature near the melting point after bonding. ing. In addition, the metal particle sintered paste is superior in heat resistance and heat dissipation as compared with an adhesive containing resin.

JP 2010-257880 A JP 2011-091213 A WO2011 / 010659 Publication WO2010 / 084746 WO2010 / 084742 Publication JP 2010-170916 A WO2009 / 090915 JP 2008-198962 A Japanese Patent Laid-Open No. 11-284234

  However, the sintered body obtained by firing the metal particle sintered paste becomes porous because the gap between adjacent metal particles becomes a void and remains inside, and the surface is caused by the shape of the metal particles. It may have a fine concavo-convex structure. For this reason, when the metal particle sintered paste is applied to bonding of light emitting elements, light loss occurs due to the uneven structure on the surface of the sintered body of metal particles, and the light extraction efficiency may be reduced.

  Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to provide a light-emitting device that is excellent in bondability between a light-emitting element and a mounting member and has high light extraction efficiency.

  In order to solve the above-described problems, a light-emitting device according to the present invention includes a substrate, a light-emitting element structure provided on the upper surface side of the substrate, and a metal reflective film provided between the substrate and the light-emitting element structure. Or a light emitting element having a bonding layer including a dielectric multilayer film, a mounting member on which the light emitting element is mounted, a sintered body of metal particles, and a lower surface side of the substrate of the light emitting element and the mounting member And a joining member for joining together.

Moreover, the light emitting device according to the present invention can be configured as follows.
The bonding member may cover at least a part of the side surface of the substrate.
You may provide the white coating | coated member which coat | covers the surface of the said joining member.
The covering member may cover at least a part of the side surface of the substrate.
The substrate may be a light shielding substrate.
The metal particles may be silver or a silver alloy.

  According to the present invention, the light emitted from the light emitting element structure is reflected upward by the bonding layer, so that the light incident on the bonding member, which is a sintered body of metal particles, is reduced, and high light extraction efficiency is obtained. Can do.

It is the schematic top view (a) of the light-emitting device which concerns on one embodiment of this invention, and the schematic sectional drawing (b) in the AA cross section. It is the schematic top view (a) of the light-emitting device which concerns on one embodiment of this invention, and the schematic sectional drawing (b) in the BB cross section.

  Hereinafter, embodiments of the invention will be described with reference to the drawings as appropriate. However, the light-emitting device described below is for embodying the technical idea of the present invention, and the present invention is not limited to the following unless otherwise specified. In addition, the size, positional relationship, and the like of members illustrated in each drawing may be exaggerated for clarity of explanation.

<Embodiment 1>
FIG. 1A is a schematic top view showing the light-emitting device according to Embodiment 1, and FIG. 1B is a schematic cross-sectional view showing the AA cross section in FIG. As shown in FIG. 1, the light-emitting device 100 according to Embodiment 1 includes a light-emitting element 10, a mounting member 20, and a joining member 30.

  The light emitting element 10 is one light emitting diode (LED) chip. The light emitting element 10 includes a substrate 11 and a light emitting element structure 13 provided on the upper surface side of the substrate. A wavelength conversion member 60 containing a phosphor is provided on the upper surface of the light emitting element 10. The wavelength conversion member 60 has substantially the same shape as the light emitting element 10 in a top view. Therefore, the light emitting element 10 can also be considered as a wavelength conversion member integrated light emitting element. A metal film 17 may be provided on the lower surface of the substrate 11.

  The mounting member 20 is a member on which the light emitting element 10 is mounted. The mounting member 20 is a package having a conductive member 21 that is a pair of positive and negative lead frames, and a base body 23 that is a molded body of resin integrally formed with the conductive member 21. The mounting member 20 includes a recess, and the light emitting element 10 is accommodated in the recess.

  The light emitting device 100 further includes a sealing member 50 that seals the light emitting element 10. The sealing member 50 is a substantially transparent resin molded body. Further, the sealing member 50 is formed in a convex surface that is filled in the concave portion of the mounting member 20 and whose surface further protrudes upward.

  The joining member 30 is a member that joins the lower surface side of the substrate 11 of the light emitting element 10 and the mounting member 20 (particularly the conductive member 21). The joining member 30 is a sintered body of the metal particles 35. The joining member 30 is obtained by firing a metal particle sintered paste, is porous, and has irregularities formed on the surface.

  The light emitting element 10 has a bonding layer 15 between the substrate 11 and the light emitting element structure 13. The bonding layer 15 includes a metal reflective film or a dielectric multilayer film. Thereby, the light emitted from the light emitting element structure 13 is efficiently reflected upward by the metal reflective film or the dielectric multilayer film of the bonding layer 15 to reduce the light incident on the bonding member 15, and from the light emitting element structure 13. It is possible to increase the light extraction efficiency by suppressing the emitted light from traveling into the substrate 11. As described above, in the present embodiment, the light emitting element 10 is bonded to the mounting member 20 by the bonding member 30 that is a sintered body of metal particles, so that the bonding member 15 is further bonded to the bonding member 15 while being excellent in heat dissipation and heat resistance. Light incidence to 30 can be reduced, and a light emitting device with high light extraction efficiency can be obtained. Note that the metal reflective film or the dielectric multilayer film of the bonding layer 15 is in contact with the light emitting element structure 13 or a light transmitting film such as a conductive oxide film provided in contact with the light emitting element structure 13. It is preferable to be provided because the light reflecting function is easily exhibited.

  Hereinafter, the preferable form of the light-emitting device 100 is explained in full detail.

  In the light emitting device 100 of the example illustrated in FIG. 1, the bonding member 30 covers a part of the side surface of the substrate 11. The bonding member 30 may cover the entire side surface of the substrate 11. As described above, since the bonding member 30 covers at least a part of the side surface of the substrate 11, the bonding strength between the light emitting element 10 and the mounting member 20 and the heat dissipation of the light emitting element 10 can be improved. In addition, the metal reflection film or the dielectric multilayer film of the bonding layer 15 can suppress the progress of light to the inside of the substrate 11 and suppress the light loss due to the bonding member 30 that covers the side surface of the substrate 11.

  In the light emitting device 100 of the example shown in FIG. 1, the surface of the bonding member 30 is covered with a covering member 40. The covering member 40 is preferably white. Thereby, the light emitted from the light emitting element structure 13 can be efficiently reflected upward by the covering member 40, the light incident on the bonding member 30 can be reduced, and high light extraction efficiency can be obtained. Further, even when the joining member 30 is deteriorated such as discoloration due to corrosive gas such as sulfur-containing gas or moisture entering from the outside of the light emitting device, the covering member 40 that covers the surface of the joining member 30 is used to join the joining member 30. Therefore, it is possible to maintain high light extraction efficiency. This is particularly effective when the metal particles 35 are silver or a silver alloy that is relatively easily discolored.

  Furthermore, in the light emitting device 100 of the example illustrated in FIG. 1, the covering member 40 covers the entire side surface of the substrate 11. As described above, since the covering member 40 covers at least a part of the side surface of the substrate 11, the covering area of the joining member 30 by the covering member 40 is increased, and light loss due to the surface of the joining member 30 can be easily suppressed. . In addition, the metal reflection film or the dielectric multilayer film of the bonding layer 15 can suppress the progress of light into the substrate 11, thereby suppressing light confinement by the covering member 40 that covers the side surface of the substrate 11. In particular, when the substrate 11 is a light-shielding substrate, light loss due to the side surface of the substrate 11 can be suppressed.

  The covering member 40 covers the side surface of the light emitting element structure 13 (particularly the active layer). Further, the covering member 40 covers the side surface of the wavelength conversion member 60. Thereby, it is possible to suppress the light from being directly emitted from the light emitting element structure 13 and the wavelength conversion member 60 to the side, the light is efficiently incident on the wavelength conversion member 60 from the light emitting element structure 13, and there are few color spots. A light emitting device capable of emitting light can be obtained. The covering member 40 continuously covers the mounting member 20 around the light emitting element 10. Thereby, the light (light from the light emitting element structure 13 and wavelength converted light from the phosphor) traveling in the sealing member 50 is efficiently reflected upward by the covering member 40, and is applied to the mounting member 20 and the bonding member 30. Light incidence can be reduced and high light extraction efficiency can be obtained.

  The covering member 40 preferably contains particles 45 having an average particle size smaller than that of the metal particles 35. Thereby, the particles 45 contained in the covering member 40 are easily arranged densely on the concave portions on the surface of the bonding member 30, and light loss due to the bonding member 30 is easily suppressed. Furthermore, it is more preferable that the particles 45 contained in the covering member 40 are disposed in the recesses on the surface of the bonding member 30, and it is even more preferable that the recesses are filled.

<Embodiment 2>
2A is a schematic top view showing the light-emitting device according to Embodiment 2, and FIG. 2B is a schematic cross-sectional view showing a BB cross section in FIG. 2A. As illustrated in FIG. 2, the light-emitting device 200 according to Embodiment 2 includes a light-emitting element 10, a mounting member 20, and a joining member 30.

  The light emitting element 10 is an LED chip including a substrate 11, a light emitting element structure 13 provided on the upper surface side of the substrate, and a bonding layer 15 provided therebetween, and a plurality of the light emitting elements 10 are provided. A metal film 17 may be provided on the lower surface of the substrate 11.

  The mounting member 20 is a wiring board having a conductive member 22 which is a wiring and a base body 24 which is a base material of a substrate having the conductive member 22 on the surface. A frame-shaped protrusion is provided on the upper surface of the mounting member 20 so as to surround all the light emitting elements 10 mounted on the conductive member 22. This protrusion is a molded body of white resin.

  The sealing member 50 is filled inside the protrusion and covers all the light emitting elements 10, and the surface thereof is formed substantially flat. The sealing member 50 is a molded body of resin containing a phosphor, and is also a wavelength conversion member 61.

  The joining member 30 is a sintered body of the metal particles 35, covers a part of the side surface in addition to the lower surface side of the substrate 11, and joins each light emitting element 10 and the mounting member 20. The joining member 30 is obtained by firing a metal particle sintered paste, is porous, and has irregularities formed on the surface.

  In the light emitting device 200 of the example shown in FIG. 2, the covering member 40 covers a part of the side surface of the substrate 11 of each light emitting element 10. Therefore, the side surface of the light emitting element structure 13 (particularly the active layer) of each light emitting element 10 is exposed from the covering member 40. Thereby, light confinement by the covering member 40 can be suppressed, and light can be efficiently extracted from the light emitting element structure 13. The covering member 40 continuously covers the mounting member 20 between the light emitting elements 10. Thereby, the light (light from the light emitting element structure 13 and wavelength converted light from the phosphor) traveling in the sealing member 50 (wavelength conversion member 61) is efficiently reflected upward by the covering member 40, and the mounting member 20 In addition, it is possible to reduce the incidence of light on the bonding member 30 and obtain high light extraction efficiency. Further, the light scattering effect of the particles 45 contained in the covering member 40 promotes the color mixture of the light from the light emitting element structure 13 and the wavelength converted light from the phosphor, and the light emitting device can emit light with less color spots. Can do.

  Hereinafter, each component of the light emitting device of the present invention will be described.

(Light emitting element 10)
The light emitting element 10 includes at least a substrate 11 and a light emitting element structure 13. The shape of the light emitting element 10 when viewed from above is preferably a quadrangle, particularly a rectangle, but may be other shapes. The side surface of the light emitting element 10 (particularly the substrate 11) may be substantially perpendicular to the upper surface, or may be inclined inward or outward.

(Substrate 11)
The substrate 11 is, for example, a bonding substrate that is bonded to the light emitting element structure 13 separated from the crystal growth substrate. Since the substrate 11 has conductivity, an upper and lower electrode structure (counter electrode structure) can be employed, and the light emitting area can be easily increased. In addition, it is easy to supply power uniformly to the light emitting element structure 13 in the surface, and it is easy to increase the light emission efficiency. Further, if there is a bonding layer 15 that suppresses the progress of light from the light emitting element structure 13 to the inside of the substrate 11, the substrate 11 can be selected by giving priority to thermal conductivity and conductivity over optical characteristics. it can. In particular, the substrate 11 is preferably a light-shielding substrate. Many of the light-shielding substrates are excellent in thermal conductivity, and it is easy to improve the heat dissipation of the light-emitting element 10. Specifically, the substrate 11 can be made of silicon, silicon carbide, aluminum nitride, copper, copper-tungsten, gallium arsenide, ceramics, or the like. Among these, silicon, silicon carbide, and copper-tungsten are preferable from the viewpoint of the difference in thermal expansion coefficient from the light emitting element structure 13, and silicon and copper-tungsten are preferable from the viewpoint of cost. The thickness of the substrate 11 is, for example, 20 μm or more and 1000 μm or less, and is preferably 50 μm or more and 500 μm or less from the viewpoint of the strength of the substrate 11 or the thickness of the light emitting devices 100 and 200.

(Light Emitting Element Structure 13)
The light-emitting element structure 13 is a stacked body of semiconductor layers, and preferably includes at least an n-type semiconductor layer and a p-type semiconductor layer, and further has an active layer interposed therebetween. The emission wavelength of the light-emitting element structure 13 can be selected from ultraviolet to infrared depending on the semiconductor material and its mixed crystal ratio. As a semiconductor material, a nitride semiconductor capable of emitting light with a short wavelength capable of efficiently exciting a phosphor (mainly general formula In _x Al _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1 X + y ≦ 1) is preferred. In addition, an InAlGaAs-based semiconductor, an InAlGaP-based semiconductor, zinc sulfide, zinc selenide, silicon carbide, or the like can also be used.

(Joining layer 15)
The bonding layer 15 is a layer for bonding the substrate 11 which is the bonding substrate described above and the light emitting element structure 13 separated from the crystal growth substrate. Silver, aluminum, rhodium, platinum, gold, or an alloy thereof can be used for the metal reflective film included in the bonding layer 15, and silver or a silver alloy excellent in light reflectivity is particularly preferable. The dielectric multilayer film included in the bonding layer 15 is, for example, any one of silicon, titanium, zirconium, niobium, tantalum, and aluminum, such as a stacked structure of (Nb ₂ O ₅ / SiO ₂ ) _n (where n is a natural number). A laminate in which at least two of the oxides or nitrides are repeatedly stacked can be used. The metal reflective film is provided on a part or all of the bonding layer 15, and the dielectric multilayer film is provided on a part of the bonding layer 15. When a metal reflective film or a dielectric multilayer film is provided on a part of the bonding layer 15, other parts of the bonding layer 15 are gold, tin, platinum, palladium, rhodium, nickel, tungsten, molybdenum, chromium, titanium, or These alloys and combinations thereof can be used. Note that the bonding layer 15 is formed by surface activated bonding, thermocompression bonding, or the like when the substrate 11 is a crystal growth substrate or when the substrate 11 is a bonding substrate and the light emitting element structure 13 separated from the crystal growth substrate. In the case of direct joining, it can be omitted.

(Metal film 17)
By providing the metal film 17 on the lower surface of the substrate 11, the bonding strength of the light emitting element 10 to the mounting member 20 can be increased, and high bonding strength can be easily obtained at a low temperature. As a material of the metal film 17, silver, platinum, gold, titanium, aluminum, or an alloy thereof can be used, and silver is particularly preferable. The metal film 17 may be a single layer film or a multilayer film. The metal film 17 can be formed by sputtering, plating, vapor deposition or the like. The metal film 17 can be omitted, and the lower surface of the substrate 11 may be in contact with the bonding member 30.

(Mounting member 20)
In many cases, the mounting member 20 includes conductive members 21 and 22 and bases 23 and 24. The mounting member may have a form in which a conductive member as a lead frame also serves as a base, like a lamp type (bullet type) light emitting device (not shown).

(Conductive members 21, 22)
The conductive members 21 and 22 are members that are electrically connected to the light emitting element 10 and supply power to the light emitting element 10. The conductive members 21 and 22 are a lead frame and wiring. Examples of the material of the conductive members 21 and 22 include copper, iron, nickel, tungsten, chromium, aluminum, silver, gold, titanium, and alloys thereof. In particular, copper or copper alloy is preferable from the viewpoint of heat dissipation, and iron or iron alloy is preferable from the viewpoint of bonding reliability with the semiconductor element. A film of silver, platinum, tin, gold, copper, rhodium, or an alloy thereof, or an oxide of silver oxide or a silver alloy may be formed on the surfaces of the conductive members 21 and 22. In particular, the surface of the part to which the semiconductor element 10 of the conductive members 21 and 22 is joined may be covered with silver. These coatings can be formed by plating, vapor deposition, sputtering, printing, coating, or the like.

(Substrate 23, 24)
The bases 23 and 24 are members that hold the conductive members 21 and 22. As the substrates 23 and 24, those having a recess (cup portion), a flat plate, or the like can be used. Those having recesses are likely to increase the light extraction efficiency, and those having a flat shape are easy to mount the light emitting element 10. The former is mainly in the form of a package, and the latter is in the form of a wiring board. As the base 23 constituting the package, in addition to the one integrally formed with the lead frame, a wiring provided by plating or the like after the package is formed may be used. Examples of the material of the substrate 23 constituting the package include thermoplastic resins such as polyphthalamide and liquid crystal polymer, thermosetting resins such as epoxy resin, glass epoxy, and ceramics. Moreover, in order to reflect the light from the light emitting element 10 efficiently, you may mix | blend white pigments, such as a titanium oxide, with these resin. As a molding method of the package, insert molding, injection molding, extrusion molding, transfer molding, or the like can be used. As the substrate 24 constituting the wiring board, a ceramic substrate containing aluminum oxide, aluminum nitride, zirconium oxide, zirconium nitride, titanium oxide, titanium nitride or a mixture thereof, copper, iron, nickel, chromium, aluminum, silver, gold, A metal substrate containing titanium or an alloy thereof, a glass epoxy substrate, a BT resin substrate, a glass substrate, a resin substrate, a paper substrate, and the like can be given. A flexible substrate (flexible substrate) such as polyimide may be used.

(Jointing member 30)
The joining member 30 is obtained by firing a metal particle sintered paste containing metal particles 35 and an organic solvent. The joining member 30 contains substantially no resin. As the metal particles 35, gold, silver, copper, nickel, palladium, platinum, rhodium, aluminum, zinc, or an alloy thereof can be used. Especially, it is preferable that the metal particle 35 is silver or a silver alloy from a viewpoint of sintering temperature or sinterability in an air atmosphere. When the metal particles are silver or a silver alloy, metal oxide particles, preferably silver oxide particles, may be added to the metal particle sintered paste. The average particle diameter (median diameter) of the metal particles 35 is preferably 0.02 μm or more and 10 μm or less, and preferably 0.06 μm or more and 7 μm or less in order to facilitate the joining of the light emitting element 10 and the mounting member 20 at a low temperature. It is more preferable. The average particle diameter (median diameter) of the metal particles 35 can be measured by a laser diffraction / scattering method or the like. The specific surface area of the metal particles 35 is, for example, 0.1 m ² / g or more ^3m 2 / g or less, preferably less 0.15 m ² / g or more 2.8m ² / g, 0.19m ² / G or more and 2.7 m ² / g or less is more preferable. When the specific surface area of the metal particles 35 is in such a range, the bonding area between the metal particles 35 can be increased, and the light emitting element 10 and the mounting member 20 can be easily joined at a low temperature. The specific surface area of the metal particles 35 can be measured by BET or the like. The metal particles 35 may be a mixture of two types of particles. In this case, the metal particles 35 are a mixture of first particles having an average particle diameter (median diameter) of 0.1 μm to 1 μm and second particles having an average particle diameter (median diameter) of 2 μm to 15 μm. It is preferable. The weight ratio of the first particles to the second particles is preferably 2: 3. By using such a mixture of particles, the light emitting element 10 and the mounting member 20 can be easily joined at a low temperature. Since the joining member 30 includes a large number of voids inside, the joining member 30 is rich in flexibility. In particular, in the case of a metal particle sintered paste containing metal particles 35 having a relatively large average particle diameter (median diameter) (for example, on the order of μm, more specifically, an average particle diameter in the above range), adjacent metals Since the gap between the particles becomes large and becomes a void and tends to remain inside, the joining member 30 tends to be porous.

  As the organic solvent, various lower alcohols can be used, but a mixture of diol and ether is preferable in order to facilitate bonding of the light emitting element 10 and the mounting member 20 at a low temperature. Examples of the diol include aliphatic diols such as 2-ethyl-1,3-hexanediol; 2,2-bis (4-hydroxycyclohexyl) propane, and alkylene oxide adducts thereof; 1,4-cyclohexanediol, and the like. Of the alicyclic diols. Examples of the ether include tripropylene glycol methyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and ethylene glycol monoethyl ether. The weight ratio between the metal particles 35 and the organic solvent is preferably 4 to 9: 1 and more preferably 8 to 9: 1 so that the light emitting element 10 and the mounting member 20 can be easily joined at a low temperature. . The metal particles 35 and the organic solvent are mixed and then filtered using a mesh or the like, so that a homogeneous metal particle sintered paste can be obtained. .

(Joining process)
The light emitting element 10 can be bonded to the mounting member 20 as follows, for example. First, a metal particle sintered paste is applied on the mounting member 20. At this time, it is preferable that the metal particle sintered paste is provided in such an amount that the entire lower surface of the light emitting element 10 is wetted. By doing so, it is easy to improve the thermal shock resistance of joining of the light emitting element 10 and the mounting member 20. Next, after the light emitting element 10 is placed on the metal particle sintered paste, the light emitting element 10 and the mounting member 20 are joined by heating. The heating temperature at this time is preferably 150 ° C. or higher and 250 ° C. or lower. The heating time is preferably 0.5 hours or more and 5 hours or less. Furthermore, the heating is preferably performed in an air atmosphere or an oxygen atmosphere. By heating in such an atmosphere, the joint points between the metal particles 35 are likely to increase, and an improvement in the joint strength between the light emitting element 10 and the mounting member 20 can be expected. In addition to the light emitting element 10, in addition to the electrostatic protection element such as a Zener diode, an electronic element such as a resistor or a capacitor may be mounted on the mounting member 20. May be joined to the mounting member 20.

(Coating member 40)
The covering member 40 is a white member that covers at least the bonding member 30. The covering member 40 can be composed of a resin containing the particles 45 or an aggregate of the particles 45. The covering member 40 can be formed by a dispensing method or the like when it is a resin containing the particles 45, and can be formed by electrophoretic electrodeposition or the like when it is an aggregate of the particles 45. The refractive index of the particles 45 is, for example, 1.8 or more, and is preferably 2 or more, more preferably 2.5 or more in order to efficiently scatter light and obtain high light extraction efficiency. . When the covering member 40 is made of a resin containing the particles 45, the difference in refractive index between the resin and the particles 45 is, for example, 0.4 or more, and the light is efficiently scattered to obtain high light extraction efficiency. 0.7 or more, more preferably 0.9 or more. The concentration of the particles 45 is preferably 10 weight percent concentration (wt%) or more and 50 weight percent concentration or less, preferably 20 weight percent concentration or more and 40 weight percent, considering preferable light reflection characteristics and ease of formation. More preferred is a weight percent concentration. The average particle diameter (median diameter) of the particles 45 is preferably 0.08 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less, at which a light scattering effect can be obtained with high efficiency. The particles 45 are preferably white. Specifically, as the particles 45, titanium oxide, zirconium oxide, magnesium oxide, magnesium carbonate, magnesium hydroxide, calcium carbonate, calcium hydroxide, calcium silicate, zinc oxide, barium titanate, aluminum oxide, or the like can be used. . Of these, titanium oxide is preferable because it is relatively stable against moisture and has a high refractive index. The same resin as the following sealing member can be used as the resin, and among these, a silicone resin or an epoxy resin is preferable, and a silicone resin that is particularly excellent in light resistance and heat resistance is more preferable. Note that the light reflectance of the covering member 40 with respect to the light emitted from the light emitting element structure 13 is preferably higher than that of the surface of the bonding member 30. The light reflectance of the covering member 40 with respect to the light emitted from the light emitting element structure 13 is preferably higher than that of the surface of the substrate 11.

(Sealing member 50)
The sealing member 50 is a member that seals the light emitting element 10, the wire, the covering member 40, a part of the conductive members 21 and 22, and protects them from dust and external force. The base material of the sealing member 50 has only to be electrically insulative and can transmit light emitted from the light emitting element structure 13 (preferably a transmittance of 70% or more). Specific examples include silicone resins, silicone-modified resins, silicone-modified resins, epoxy resins, phenol resins, polycarbonate resins, acrylic resins, TPX resins, polynorbornene resins, or hybrid resins containing one or more of these resins. Glass may be used. Of these, silicone resins are preferred because they are excellent in heat resistance and light resistance and have little volume shrinkage after solidification. In particular, the base material of the sealing member 50 is preferably composed mainly of phenyl silicone resin. When the surface of the sealing member 50 is a convex surface, the phenyl silicone resin is more excellent in light extraction efficiency than the dimethyl silicone resin. In addition, the phenyl silicone resin is excellent in gas barrier properties and easily suppresses deterioration of the conductive members 21 and 22 due to corrosive gas.

  The sealing member 50 may include particles having various functions such as a filler and a phosphor in the base material. As the filler, a diffusing agent, a coloring agent, or the like can be used. Specifically, silica, titanium oxide, magnesium oxide, magnesium carbonate, magnesium hydroxide, calcium carbonate, calcium hydroxide, calcium silicate, zinc oxide, barium titanate, aluminum oxide, iron oxide, chromium oxide, manganese oxide, glass And carbon black. The shape of the filler particles may be crushed or spherical. Further, it may be hollow or porous.

The phosphor absorbs at least part of the primary light emitted from the light emitting element structure 13 and emits secondary light having a wavelength different from that of the primary light. Specifically, activated yttrium aluminum garnet with cerium (YAG), europium and / or chromium activated nitrogen containing calcium aluminosilicate _{(CaO-Al2O 3 -SiO 2)} , activated silicates europium ( (Sr, Ba) ₂ SiO ₄ ) and the like. Thus, a light emitting device that emits mixed light (for example, white light) of primary light and secondary light having a visible wavelength, or a light emitting device that emits visible light secondary light when excited by the primary light of ultraviolet light is used. Can do.

(Wavelength conversion member 60, 61)
The wavelength conversion members 60 and 61 are translucent members containing the above phosphors. Specifically, the wavelength conversion members 60 and 61 are formed by adding a phosphor to the same resin or glass base material as that of the sealing member 50, a phosphor crystal or sintered body, or A sintered body of a phosphor and an inorganic binder can be used. The wavelength conversion members 60 and 61 can be formed in a flat plate shape or a thin film shape as shown in FIG. 1, and the surface thereof may be a convex surface, a concave surface, an uneven surface, or the like. In particular, the wavelength conversion member 60 is provided in the vicinity of the light emitting element 10, and the sealing member 50 does not substantially contain the phosphor, so that the wavelength of light by the phosphor is limited to the vicinity of the light emitting element 10. Since conversion and scattering are performed, the light source portion can be made smaller with respect to the surface of the sealing member 50, the light extraction efficiency can be easily improved, and the optical design of the device using the light emitting device as a light source is facilitated.

  Examples according to the present invention will be described in detail below. Needless to say, the present invention is not limited to the following examples.

<Example 1>
The light emitting device of Example 1 is a surface-mount type LED having a structure similar to the example shown in FIG. In Example 1, the light emitting device is manufactured as follows.

First, the metal particles 35 and the organic solvent are mixed at a weight ratio of 5: 0.47 to obtain a metal particle sintered paste. The metal particles 35 are flaky silver particles (product name “AgC-239” (manufactured by Fukuda Metal Foil Powder Co., Ltd.), average particle diameter (median diameter): 2.0 to 3.2 μm, specific surface area: 0.6. -0.9 m ² / g) and spherical silver particles (product name “EHD” (manufactured by Mitsui Metal Mining Co., Ltd.), average particle diameter (median diameter): 0.4-1.2 μm, specific surface area: 1.6 m ² / g) and a weight ratio of 6: 4. The organic solvent is a mixture of 2-ethyl-1,3-hexanediol and diethylene glycol monobutyl ether in a weight ratio of 8: 2.

  The mounting member 20 is configured by integrally molding a resin molded body serving as a base 23 on a lead frame which is a pair of positive and negative conductive members 21. The conductive member 21 is obtained by processing a copper plate having a surface plated with silver by pressing or etching. The substrate 23 is made of a polyphthalamide resin containing a filler. The mounting member 20 is provided with a recess including the upper surface of the conductive member 21 on the bottom surface.

  The light emitting element 10 is a substantially rectangular parallelepiped LED chip having a 2 mm square in a top view. The light emitting element 10 is formed by bonding a light emitting element structure 13 of a nitride semiconductor having a thickness of 4 μm to an upper surface of a silicon substrate 11 having a thickness of 0.3 mm. The bonding layer 15 includes a silver metal reflective film on the light emitting element structure 13 side, and most of the other is made of gold-tin. A silver metal film 17 having a thickness of 0.5 μm is provided on the lower surface of the substrate 11. Further, on the upper surface of the light emitting element structure 13, a molded body of a silicone resin (thickness: 50 μm) containing a gold protruding electrode and a YAG: Ce phosphor as a wavelength conversion member 60 covering a region excluding the protruding electrode. And are provided.

  The metal particle sintered paste is applied to the upper surface of the conductive member 21 located on the bottom surface of the recess by a stamping method, and the light emitting element 10 is mounted thereon. Next, the mounting member 20 on which the light emitting element 10 is mounted is heated in an air atmosphere at 120 ° C. for 30 minutes, further at 175 ° C. for 90 minutes, and then cooled. As a result, the metal particle sintered paste is fired to form a porous sintered joined member 30, and the lower surface side of the substrate 11 of the light emitting element 10 is joined to the conductive member 21. Note that the bonding member 30 covers a part of the side surface of the substrate 11.

  Next, the protruding electrode of the light emitting element 10 and the conductive member 21 are connected by a gold wire. After that, the covering member 40 is prepared by blending titanium oxide particles 45 having an average particle diameter of about 0.3 μm and a refractive index of about 2.5 in a silicone resin having a refractive index of about 1.4 at a concentration of 30 wt%. The bonding member 30 is coated so as to be covered by a dispensing method. At this time, the covering member 40 is provided so as to cover at least a part of the side surface of the substrate 11 of the light emitting element, and to cover the bottom surface of the recess of the mounting member 20 around the light emitting element 10 (particularly, the conductive member 21). Finally, a silicone resin sealing member 50 is provided on the mounting member 20 so as to have a substantially hemispherical surface to obtain a light emitting device.

<Example 2>
The light emitting device of Example 2 is manufactured in the same manner as Example 1 except that the covering member is not provided.

<Comparative Example 1>
The light emitting device of Comparative Example 1 uses a gold-tin paste containing a flux and having a melting point of about 280 ° C., instead of the silver particle sintered paste, except that bonding is performed in a reflow furnace near 300 ° C. It is produced in the same manner as in Example 2. However, in the light emitting device of Comparative Example 1, the light emitting element was destroyed in the cooling process of the reflow furnace. It is considered that the light emitting element could not withstand the stress at the time of cooling the copper lead frame having a large expansion coefficient due to the bonding at a high temperature.

<Comparative example 2>
The light emitting device of Comparative Example 2 is manufactured in the same manner as Comparative Example 1 except that the lead frame is made of a composite material of iron and copper instead of copper.

<Verification 1>
For the light emitting devices of Examples 1 and 2 and Comparative Example 2, the luminous flux is measured using an integrating sphere. The forward current is 350 mA, and the comparison is made at chromaticity x = 0.32, y = 0.32 (according to the International Commission on Illumination (CIE) xyz color system). The luminous flux of the light emitting device of Example 1 is 158.36 lumens, the luminous flux of the light emitting device of Example 2 is 156.69 lumens, and the luminous flux of the light emitting device of Comparative Example 2 is 157.25 lumens. Thus, it can be confirmed that the light emitting device of Example 1 can obtain a higher luminous flux than the light emitting devices of Example 2 and Comparative Example 2. Moreover, it can be confirmed that the light emitting device of Example 1 can suppress the damage of the constituent members as compared with the light emitting device of Comparative Example 1.

<Verification 2>
For the light emitting devices of Examples 1 and 2 and Comparative Example 2, the luminous flux maintenance factor before and after the sulfidation test is measured. In the sulfidation test, a light emitting device and 1 g of sodium sulfide are placed in a pressure vessel and heated in an oven at 120 ° C. for 20 hours. The luminous flux maintenance factor of the light emitting device of Example 1 is 98.1%, the luminous flux maintenance factor of the light emitting device of Example 2 is 97.9%, and the luminous flux maintenance factor of the light emitting device of Comparative Example 2 is 97.0%. Thus, even after the sulfidation test, it can be confirmed that the light emitting device of Example 1 can maintain a higher luminous flux than the light emitting devices of Example 2 and Comparative Example 2.

  The light emitting device according to the present invention includes a backlight source of a liquid crystal display, various lighting devices, a large display, various display devices such as advertisements and destination guidance, and an image reading device in a digital video camera, a facsimile, a copier, a scanner, and the like It can be used for projector devices.

  DESCRIPTION OF SYMBOLS 10 ... Light emitting element (11 ... Board | substrate, 13 ... Light emitting element structure, 15 ... Joining layer, 17 ... Metal film), 20 ... Mounting member (21, 22 ... Conductive member, 23, 24 ... Base | substrate), 30 ... Joining member ( 35 ... metal particles), 40 ... coating member (45 ... particles), 50 ... sealing member, 60, 61 ... wavelength conversion member, 100, 200 ... light emitting device

Claims (7)

A light emitting device comprising: a substrate; a light emitting device structure provided on an upper surface side of the substrate; and a bonding layer including a metal reflective film or a dielectric multilayer film provided between the substrate and the light emitting device structure; ,
A mounting member on which the light emitting element is mounted;
A sintered body of metal particles, covering at least part of the side surface of the substrate, and a bonding member for bonding the lower surface side of the substrate of the light emitting element and the mounting member;
A white covering member that covers at least part of the side surface of the substrate and the surface of the bonding member;
With
The side surface of the light emitting element is perpendicular to the upper surface, or is inclined inward or outward,
The light emitting device, wherein the covering member does not cover the light emitting element structure. 2. The light emitting device according to claim 1, wherein the covering member contains white particles in a resin, and the concentration of the white particles with respect to the covering member is not less than 10 wt% and not more than 50 wt%.   The light emitting device according to claim 1, wherein the joining member does not substantially contain a resin. 4. The light emitting device according to claim 2, wherein an average particle diameter (median diameter) of the white particles is from 0.1 μm to 5 μm.   The light emitting device according to claim 1, wherein the substrate is a light shielding substrate.   The light emitting device according to claim 1, wherein the metal particles are silver or a silver alloy.   The light emitting device according to claim 1, wherein the metal particles have a size of 0.02 μm to 10 μm.

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