JP2011096740A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device which further suppresses secondary absorption at a wavelength conversion layer and exhibits higher luminous efficiency. <P>SOLUTION: The light-emitting device includes: a first LED chip (a first light-emitting element ) 11 mounted on one surface 4a of a mounting substrate 4; a first wavelength conversion layer 12 arranged on the first LED chip 11, absorbing a part of blue light from the first LED chip 11, and emitting green fluorescent light; a second LED chip (a second light-emitting element) 21 mounted on a recessed part 4b of the mounting substrate 4; a second wavelength conversion layer 22 arranged on the second LED chip 21 in the recessed part 4b, absorbing a part of the blue light from the second LED chip 21, and emitting red fluorescent light having a longer wavelength than green fluorescent light of the first wavelength conversion layer 12. At least a part of a line connecting an optional point on an end surface 12a for radiating light from the first wavelength conversion layer 12 to an external and an optional point on a surface for radiating light from the second wavelength conversion layer 22 to an external intersect with the one surface 4a of the mounting substrate 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light emitting device and a light emitting device using a wavelength conversion layer that converts the wavelength of light from the light emitting device.

  In recent years, a light emitting element made of a semiconductor such as an LED chip mounted on a mounting substrate, and a fluorescent material that covers the light emitting element, absorbs at least a part of the light from the light emitting element, and converts the wavelength to emit a complementary color light. For example, a light emitting device has been developed that emits white light in which blue light from a light emitting element and yellow light from a wavelength conversion layer are mixed. . This type of light-emitting device has been used for lighting fixtures as the light output of the light-emitting element becomes more efficient.

  By the way, in order to make the white light emitted closer to natural light, the light emitting device combines a light emitting element that emits blue light, a green phosphor that emits green light, a red phosphor that emits red light, and the like. May be used to enhance the color rendering of white light.

  A light-emitting device provided with such a wavelength conversion layer containing a plurality of types of phosphors emits a part of light converted by a phosphor having a light emission peak wavelength shorter (for example, a green phosphor). The longer wavelength phosphor (for example, red phosphor) absorbs (hereinafter referred to as secondary absorption) and converts the wavelength. Therefore, the light emitting device cannot sufficiently increase the light emission efficiency due to the overlap of the loss accompanying the wavelength conversion in the phosphor.

  Therefore, in order to suppress secondary absorption between multiple types of phosphors, a light-emitting device having a structure in which a wavelength conversion layer containing a green phosphor and a wavelength conversion layer containing a red phosphor are separated is considered. ing. For example, as shown in FIG. 10, the first LED chip 11 that is a first light emitting element mounted on one surface of the mounting substrate 4 and the entire first LED chip 11 are covered to form the first LED. A first wavelength conversion layer 12 ′ that absorbs at least a part of light from the chip 11 and emits fluorescence, and a second light emitting element mounted on the inner bottom surface of the recess 4 b that is recessed from the one surface of the mounting substrate 4. The second LED chip 21 and the entirety of the second LED chip 21 in the recess 4b are covered to absorb at least a part of the light from the second LED chip 21, and the first wavelength conversion layer A light emitting device 10 ′ having a second wavelength conversion layer 22 ′ that emits fluorescence having a wavelength longer than 12 ′ has been proposed (see, for example, Patent Document 1). The LED chips 11 and 21 are configured to be electrically connected to the lead electrodes 13 provided on the mounting substrate 4 via the conductive wires 15 so that power can be supplied.

  In the light emitting device 10 ′ shown in FIG. 10, the second LED chip 21 and the second wavelength conversion layer 22 ′ are accommodated in the recess 4 b of the mounting substrate 4, so that the light is emitted from the first wavelength conversion layer 12 ′. The light is not secondarily absorbed by the second wavelength conversion layer 22 ′, and efficient light emission is possible.

JP 2004-71726 A

  However, the light emitted from the first LED chip 11 of the light emitting device 10 ′ having the configuration shown in FIG. 10 is not only directly above the first LED chip 11 of the first wavelength conversion layer 12 ′ but also recessed. The first wavelength conversion layer 12 ′ on 4b is also irradiated. The light emitted from the phosphor of the first wavelength conversion layer 12 'of the light emitting device 10' is emitted isotropically in all directions. Therefore, in the light emitting device 10 ′, the first wavelength conversion layer 12 ′ receives the light from the first LED chip 11 and emits isotropic fluorescence, so the second wavelength conversion layer 22 ′ in the recess 4b. In some cases, secondary absorption occurs due to light irradiation, and it is difficult to sufficiently improve the light emission efficiency of the light emitting device 10 ′.

  In particular, in the light emitting device 10 ′ used for lighting applications, higher light output is required, and the secondary absorption in the second wavelength conversion layer 22 ′ increases as the light output of the light emitting device 10 ′ increases. Therefore, the structure of the light emitting device 10 ′ described above is not sufficient and further improvement is required.

  This invention is made | formed in view of the said reason, The objective is to suppress the secondary absorption in a wavelength conversion layer more, and to provide a light-emitting device with higher luminous efficiency.

  According to a first aspect of the present invention, there is provided a first light emitting element mounted on one surface of a mounting substrate, and a fluorescent light that is provided on the first light emitting element and absorbs at least part of light from the first light emitting element. A first wavelength conversion layer that emits light, a second light emitting element mounted on an inner bottom surface of a recess recessed from the one surface of the mounting substrate, and provided in the recess and on the second light emitting element And a second wavelength conversion layer that absorbs at least part of light from the second light emitting element and emits fluorescence having a longer wavelength than the fluorescence of the first wavelength conversion layer, A line segment connecting any one point on the end face on the second wavelength conversion layer side that emits light from the wavelength conversion layer to the outside and any one point on the surface that emits light from the second wavelength conversion layer to the outside At least a portion of which intersects with the one surface of the mounting substrate.

  According to the present invention, any one point on the end surface on the second wavelength conversion layer side that emits light from the first wavelength conversion layer to the outside, and any surface on the surface that emits light from the second wavelength conversion layer to the outside For example, the first wavelength conversion layer generated by absorbing blue light emitted from the first light emitting element by at least a part of a line connecting one point intersecting one surface of the mounting substrate. It is possible to prevent the green light from being incident on the second wavelength conversion layer and secondarily absorbed, thereby obtaining a light emitting device with higher luminous efficiency.

  According to a second aspect of the present invention, in the first aspect of the present invention, the concave portion has a tapered portion that extends from the inner bottom surface toward the outside of the concave portion.

  According to this invention, the concave portion has a tapered portion that widens toward the outside, so that the light emitted from the second light emitting element and the second wavelength conversion layer can be easily emitted outside the concave portion. It is possible to reduce the reflection loss of light and suppress the decrease in the light emission efficiency of the light emitting device. In addition, the light distribution of the light from the second light emitting element and the second wavelength conversion layer emitted from the concave portion becomes a wide angle, and the light emitted from the second light emitting element and the second wavelength conversion layer Further, the color mixture of the light emitted from the first light emitting element and the first wavelength conversion layer is further promoted, and the color unevenness of the light emitting device can be reduced.

  According to a third aspect of the present invention, in the invention according to the first or second aspect, the concave portion is provided with a reflective layer that reflects light on at least an inner surface facing the outside of the concave portion. To do.

  According to this invention, the light emitted from the second light emitting element and the second wavelength conversion layer in the concave portion is reflected by the reflective layer provided on the inner surface of the concave portion. It is possible to reduce the light reflection loss that occurs in the light-emitting device, and to suppress the reduction in the light-emitting efficiency of the light-emitting device.

  The invention of claim 4 is the invention according to any one of claims 1 to 3, wherein the first light emitting element and the first wavelength conversion layer are covered with a first translucent member. The second light emitting element and the second wavelength conversion layer are covered with a second light transmissive member, and the first light transmissive member is the second light transmissive member. The refractive index is larger than that of the second translucent member.

  According to this invention, the light emitted from the first wavelength conversion layer and the first light emitting element and transmitted through the first light transmissive member is the second wavelength conversion layer and the second light emission. Even if it goes to the element side, since it is reflected at the interface with the second light transmissive member having a refractive index relatively smaller than that of the first light transmissive member, the second light transmissive member Secondary absorption by the coated second wavelength conversion layer is suppressed, and a decrease in light emission efficiency of the light emitting device can be further suppressed.

  According to a fifth aspect of the present invention, in the invention of the fourth aspect, the interface between the first light transmissive member and the second light transmissive member is more than the second light transmissive member. A third translucent member having a large refractive index and a smaller refractive index than the first translucent member is provided.

  According to this invention, the first translucent resin is provided at the interface where the first translucent member and the second translucent member are in contact with each other, whereby the first translucent resin is provided. The light emitted from the first wavelength conversion layer that was not reflected at the interface between the member and the third light transmissive member is transmitted between the third light transmissive member and the second light transmissive member. It can be reflected at the interface. Therefore, the light emitting device as a whole further suppresses light from the first wavelength conversion layer from the first light transmitting member toward the second light transmitting member, and further suppresses a decrease in light emission efficiency. It becomes possible.

  The invention according to claim 6 is the invention according to claim 4 or 5, wherein the second translucent member has a diffusing material dispersed therein.

  According to this invention, since the diffusing material is dispersed in the second light-transmissive member, the light from the second light emitting element and the second wavelength conversion layer spreads out from the concave portion. Thus, the light is distributed so that light is emitted, so that color mixing with the light emitted from the first light emitting element and the first wavelength conversion layer is promoted. Therefore, the light emitting device can emit mixed color light with less color unevenness.

  In the invention of claim 1, any one point on the end face on the second wavelength conversion layer side that emits light from the first wavelength conversion layer on the first light emitting element mounted on one surface of the mounting substrate to the outside; , At least a part of a line segment connecting with an arbitrary point on the surface that emits light from the second wavelength conversion layer on the second light emitting element in the recess recessed from the one surface of the mounting substrate. By intersecting with the one surface of the mounting substrate, there is a remarkable effect that secondary absorption in the second wavelength conversion layer can be further suppressed and a light emitting device with higher luminous efficiency can be provided.

1 is a schematic cross-sectional view showing a light emitting device of Embodiment 1. FIG. The secondary absorption in the wavelength conversion layer of a light-emitting device is shown, (a) is explanatory drawing of the light-emitting device for a comparison, (b) is explanatory drawing of the light-emitting device of Embodiment 1. FIG. 6 is a schematic cross-sectional view showing another light emitting device of Embodiment 1. FIG. The explanation of the reflection loss of light in the recess of the light emitting device is shown, (a) is an explanatory view of the light emitting device for comparison, (b) is an explanatory view of the light emitting device of the first embodiment. 3 is a schematic cross-sectional view showing another light emitting device of Embodiment 1. FIG. FIG. 6 is a schematic cross-sectional view showing a main part of a light emitting device according to Embodiment 2. It is explanatory drawing explaining the total reflection of the light in a light-emitting device same as the above. FIG. 6 is a schematic cross-sectional view of a main part showing another light emitting device of Embodiment 2. It is a schematic sectional drawing which shows another light-emitting device same as the above. It is a schematic sectional drawing which shows the conventional light-emitting device.

(Embodiment 1)
Hereinafter, the light-emitting device of this embodiment will be described with reference to FIGS. In FIG. 1 to FIG. 5, the same members are denoted by the same reference numerals and redundant description is omitted.

  The light emitting device 10 shown in FIG. 1 of the present embodiment includes a first LED chip 11 that is a first light emitting element that emits blue light mounted on one surface (reference surface) 4a of the mounting substrate 4, and a first LED. A first wavelength conversion layer 12 comprising a translucent resin layer provided on the LED chip 11 and containing a green phosphor that absorbs part of the blue light from the first LED chip 11 and emits green fluorescence; have. The light emitting device 10 includes a second LED chip 21 as a second light emitting element that emits blue light mounted on the inner bottom surface 4bb of the recess 4b that is recessed from the one surface 4a of the mounting substrate 4, and the recess 4b. The red light having a longer wavelength than the green fluorescence of the first wavelength conversion layer 12 by absorbing a part of the blue light from the second LED chip 21, which is provided on the second LED chip 21. And a second wavelength conversion layer 22 made of a translucent resin layer containing a red phosphor that emits light.

  In the light emitting device 10, the first wavelength conversion layer 12 that emits green fluorescence on the first LED chip 11 and the first LED chip 11 is used as the short wavelength light emitting unit 1, and the second LED chip 21 and the second LED chip 21. The second wavelength conversion layer 22 that emits red fluorescence on the LED chip 21 is the long wavelength light emitting section 2. In particular, the light-emitting device 10 has an arbitrary end surface 12a on the second wavelength conversion layer 22 side that emits light from the first wavelength conversion layer 12 to the short wavelength light emission unit 1 and the long wavelength light emission unit 2 to the outside. At least a part of a line segment connecting one point and any one point on the surface that emits light from the second wavelength conversion layer 22 to the outside intersects with the one surface 4 a of the mounting substrate 4.

  More specifically, the light emitting device 10 uses a mounting substrate 4 in which a pair of conductor patterns (not shown) plated with Au are formed on a rectangular flat alumina ceramic substrate. The mounting substrate 4 is formed with a recess 4 b that is recessed from the one surface 4 a of the mounting substrate 4. A plurality of Au bumps 3 are provided on each of the first and second LED chips 11 and 21 in the pair of conductor patterns of the mounting substrate 4. The first LED chip 11 mounted on the one surface 4a of the mounting substrate 4 and the second LED chip 21 housed in the recess 4b recessed from the one surface 4a of the mounting substrate 4 are respectively formed on the sapphire substrate. An n-type gallium nitride compound semiconductor layer, a light emitting layer made of a gallium nitride compound semiconductor containing In, and a p-type gallium nitride compound semiconductor layer are sequentially stacked. In the first and second LED chips 11 and 21, a part of the light emitting layer and the p-type gallium nitride compound semiconductor layer are removed, and the n-type gallium nitride compound semiconductor layer is partially exposed. An anode electrode and a cathode electrode that are electrically connected to the p-type and n-type gallium nitride compound semiconductor layers are respectively provided on the same plane side. The first and second LED chips 11, 21 are arranged such that the anode electrode and the cathode electrode provided on the same plane side of the first and second LED chips 11, 21 are placed on a pair of conductor patterns on the mounting substrate 4. The Au bump 3 is mounted so as to be able to supply power by flip chip mounting.

  The first and second LED chips 11 and 21 mounted on the one surface 4a of the mounting substrate 4 and in the recess 4b of the mounting substrate 4 have a peak wavelength within a range of, for example, 450 nm to 470 nm by energization. Each emits blue light. The outer shapes of the first and second LED chips 11 and 21 can be, for example, about 1 mm square and about 100 μm thick.

The first wavelength conversion layer 12 is a green phosphor capable of absorbing green light from the first LED chip 11 and emitting green light (for example, (SrBa) ₂ SiO ₄ activated with Eu) ) Is uniformly dispersed in a silicone resin serving as a binder, and the outer shape is approximately the same as that of the first LED chip 11 and is formed in a film shape having a thickness of approximately 100 μm. The short wavelength light emission part 1 can be formed by adhere | attaching and forming the 1st wavelength conversion layer 12 on the 1st LED chip 11 with the adhesive agent which has translucency.

  Similarly, the second LED chip 21 mounted on the inner bottom surface 4bb of the recess 4b that is recessed from the one surface 4a of the mounting substrate 4 is also the same as the first LED chip 11, and the peak wavelength is increased by energization. Emits blue light in the range of 450 nm to 470 nm, for example.

The second wavelength conversion layer 22 is a silicone that serves as a binder with a red phosphor (for example, CaAlSiN ₃ activated by Eu) that can absorb blue light from the second LED chip 21 and emit red light. The resin is uniformly dispersed in the resin, and the outer shape is approximately the same as that of the second LED chip 21, and is formed in a film shape having a thickness of approximately 100 μm. By forming the second wavelength conversion layer 22 on the second LED chip 21 by adhering with a translucent adhesive, the long wavelength light emitting section 2 can be formed.

  By the way, the light emitting device 10 is usually mounted in order to efficiently radiate light from the first and second LED chips 11 and 21 and the first and second wavelength conversion layers 12 and 22 to the outside of the light emitting device 10. It is conceivable that the one surface 4a of the substrate 4 is made of a material having a high reflectance with respect to light from the first and second LED chips 11 and 21 and the first wavelength conversion layer 12. Therefore, for example, in the case of the light emitting device 10 ″ shown in FIG. 2A, the light is emitted from the end face 12a of the first wavelength conversion layer 12 containing the green phosphor of the short wavelength light emitting unit 1 to the long wavelength light emitting unit 2 side. Green light (shaded portion indicated by an arrow in the figure) is reflected directly by the light toward the second wavelength conversion layer 22 containing a red phosphor and the one surface 4a of the mounting substrate 4 to be second Some light passes through the LED chip 21 and travels toward the second wavelength conversion layer 22.

  Compared to the light emitting device 10 ″ shown in FIG. 2A, the light emitting device 10 of the present embodiment shown in FIG. 2B includes a short wavelength light emitting unit 1 and a long wavelength light emitting unit 2 having a first wavelength. An arbitrary point on the end face 12a on the second wavelength conversion layer 22 side that emits light from the conversion layer 12 to the outside, and an arbitrary point on the surface that emits light from the second wavelength conversion layer 22 to the outside At least a part of the connecting line segment is arranged so as to intersect with the one surface 4a of the mounting substrate 4. Therefore, in the case of the light emitting device 10 of FIG. Part of the green light (shaded portion indicated by an arrow in the figure) emitted from the end face 12a of the conversion layer 12 to the long wavelength light emitting unit 2 side is shielded by the one surface 4a of the mounting substrate 4. The light-emitting device 10 in FIG. 2B is the second wavelength conversion compared with the light-emitting device 10 ″ in FIG. The light directed to the 22 is small, it is possible to suppress a decrease in luminous efficiency due to the secondary absorption in the second wavelength conversion layer 22.

  Hereinafter, each component used for the light-emitting device 10 of this embodiment is explained in full detail.

  The first and second light-emitting elements used in the light-emitting device 10 of Embodiment 1 can emit light when energized. The light emitted from the first and second light emitting elements can be, for example, blue light having a peak wavelength of 450 nm to 470 nm in visible light, but is not limited to blue light, and has other wavelengths. Ultraviolet light may be used to efficiently excite the light, the first wavelength conversion layer 12 and the second wavelength conversion layer 22. As the LED chips 11 and 21 as light emitting elements, for example, an n-type gallium nitride compound semiconductor layer, a multiple quantum well structure on a crystal growth substrate such as a sapphire substrate, a spinel substrate, a gallium nitride substrate, a zinc oxide substrate or a silicon carbide substrate. And a gallium nitride compound body layer containing indium and a p-type gallium nitride compound semiconductor layer, which are light emitting layers having a single quantum well structure, are sequentially stacked.

  Note that the LED chips 11 and 21 using the insulating substrate have anodes on the same plane side by exposing a part of the n-type gallium nitride compound semiconductor layer from the p-type gallium nitride semiconductor layer side. An electrode and a cathode electrode can be formed respectively. Moreover, what is necessary is just to form the anode electrode and the cathode electrode in the LED chip 11 and 21 using the electroconductive board | substrate on the both surfaces side of the thickness direction of the LED chip 11 and 21. FIG.

  The anode electrode and the cathode electrode provided on the LED chips 11 and 21 are materials that can obtain good ohmic characteristics with a laminated film of a Ni film and an Au film, a gallium nitride compound semiconductor layer such as an Al film and an ITO film, and the like. If there is, it is not limited.

  The LED chips 11 and 21 provided with the anode electrode and the cathode electrode on the same plane side can be flip-chip mounted on a pair of conductive patterns on the mounting substrate 4 using metal bumps such as Au bumps 3. When the LED chips 11 and 21 having the anode electrode and the cathode electrode formed on both sides in the thickness direction are used as the LED chips 11 and 21, on the mounting substrate 4 on which the LED chips 11 and 21 are mounted. One conductor pattern of the formed pair of conductor patterns and the anode electrode or the cathode electrode of the LED chips 11 and 21 are die-bonded via a conductive member (for example, AuSn or Ag paste). Connect them electrically. Further, the other cathode electrode or anode electrode on the light extraction surface side of the LED chips 11 and 21 may be electrically connected to the other conductor pattern via a wire (for example, a gold wire or an aluminum wire). Good.

  In the light emitting device 10 of the present embodiment, one first LED chip 11 is mounted on the one surface 4 a on the mounting substrate 4, and one second LED chip 21 is mounted in the recess 4 b of the mounting substrate 4. However, the number of LED chips 11 and 21 is not limited to one, and a plurality of LED chips can be used. In this case, the LED chips 11 and 21 may be electrically connected in series, parallel, or series-parallel as appropriate. The first and second LED chips 11 and 21 may be of the same type, or may be a plurality of LED chips 11 and 21 that emit different emission wavelengths.

  Next, the mounting substrate 4 used in the light emitting device 10 of the present embodiment can mount the first and second LED chips 11 and 21 as light emitting elements. The mounting substrate 4 has a recess 4b that is recessed from the one surface 4a on which the first LED chip 11 is mounted and on which the second LED chip 21 is mounted. Further, the mounting substrate 4 may constitute a current-carrying path for the LED chips 11 and 21 by using the pair of conductor patterns (for example, a conductor pattern plated with Au on the outermost surface) on the mounting substrate 4. . As the mounting substrate 4, a ceramic substrate using alumina, aluminum nitride, or the like, a metal base substrate using a metal material such as Fe, Cu, or Al, a glass epoxy resin substrate, or the like can be used. When an alumina ceramic substrate is used as the mounting substrate 4, it is easy to form a conductor pattern, has higher thermal conductivity than a glass epoxy resin substrate, etc., and efficiently generates heat generated by lighting the LED chips 11 and 21. The heat radiation of the light emitting device 10 can be enhanced by sufficiently dissipating heat. When the metal substrate is used as the mounting substrate 4, an insulating layer may be appropriately formed on the metal substrate so that the LED chips 11 and 21 are not electrically short-circuited.

  In addition, although the light-emitting device 10 of this embodiment uses the rectangular flat plate-shaped mounting substrate 4, the first LED chip 11 and the first wavelength conversion layer 12 are disposed on the periphery of the one surface 4 a of the mounting substrate 4. The mounting substrate 4 provided with a reflector that reflects the light from the light may be used, or may be formed using a lead frame provided with a cup. When a lead frame having a cup is used as the mounting substrate 4, the light emitting device 10 mounts the first LED chip 11 on the bottom surface of the cup and the inner bottom surface 4bb of the recess 4b recessed from the bottom surface of the cup. The second LED chip 21 may be mounted on the board. In addition, the light emitting device 10 includes a translucent member (for example, translucent silicone resin, epoxy resin) that protects the first and second LED chips 11, 21 and the first and second wavelength conversion layers 12, 22. Acrylic resin, polycarbonate resin, glass, or the like) may be separately provided on the first and second wavelength conversion layers 12 and 22.

  The mounting substrate 4 of the present embodiment includes a short wavelength light emitting portion 1 on the one surface 4 a of the mounting substrate 4 and a long wavelength light emitting portion 2 on the inner bottom surface 4 bb of the recess 4 b from the first wavelength conversion layer 12. At least one line segment connecting any one point on the end face 12a on the second wavelength conversion layer side that emits light to the outside and any one point on the surface that emits light from the second wavelength conversion layer 22 to the outside. The part is configured to intersect with the one surface 4 a of the mounting substrate 4. The distance between the short wavelength light emitting unit 1 and the long wavelength light emitting unit 2 is determined by the degree of secondary absorption of light from the first wavelength conversion layer 12 in the second wavelength conversion layer 22 and from the first wavelength conversion layer 12. What is necessary is just to set suitably according to the light quantity, the color tone difference of the mixed color light radiated | emitted from the light-emitting device 10, etc. FIG.

  Here, the end face 12a is a state in which red fluorescence is emitted from the second wavelength conversion layer 22 and nothing is obstructed from the surface of the second wavelength conversion layer 22 other than the second wavelength conversion layer 22. The surface of the first wavelength conversion layer 12 projected on the first wavelength conversion layer 12 from which the green fluorescence is emitted to the outside may be a flat surface or a curved surface. Moreover, the surface which radiates | emits light from the 2nd wavelength conversion layer 22 outside is the 2nd wavelength conversion from which the fluorescence which the 2nd wavelength conversion layer 22 radiates | emits can finally be taken out of the light-emitting device 10. It may be the surface of the layer 22, and if the second LED chip 21 has translucency with respect to the light emitted from the second wavelength conversion layer 22, it includes the surface in contact with the second LED chip 21. But you can.

  Moreover, the shape of the recessed part 4b recessed from the said one surface 4a of the mounting board | substrate 4 can be suitably set as desired, such as columnar shape, prismatic shape, inverted truncated cone shape, inverted truncated pyramid shape. In particular, the concave portion 4b is formed from the inner bottom surface 4bb of the concave portion 4b in which the long wavelength light emitting portion 2 is disposed as shown in the light emitting device 10 of FIG. By having the taper part which spreads toward the exterior of the recessed part 4b, the fall of the light emission efficiency of the light-emitting device 10 can be suppressed. That is, the light emitted from the second LED chip 21 and the second wavelength conversion layer 22 of the long wavelength light emitting unit 2 is reflected by the inner side surface 4ba of the recess 4b. Here, when the inner side surface 4ba of the concave portion 4b shown in the explanatory diagram of FIG. 4A is perpendicular to the inner bottom surface 4bb of the concave portion 4b, the light reflected by the inner side surface 4ba of the concave portion 4b (the arrow in FIG. Is not taken out of the recess 4b, but returns to the second wavelength conversion layer 22 side, where it is reflected and absorbed again.

  For example, the reflection loss of light in the recess 4b of the mounting substrate 4 is a case where a white resist film in which a resin containing a white pigment such as barium titanate is applied to the recess 4b of the mounting substrate 4 is formed. However, a reflection loss of about 30% occurs in one reflection. Therefore, in the light emitting device 10 of FIG. 4A, the light loss due to the repeated reflection and absorption in the recess 4b is integrated, and the light emission efficiency is greatly reduced. On the other hand, in the concave portion 4b shown in the explanatory diagram of FIG. 4B, since the concave portion 4b has a tapered portion, light (see the arrow in the drawing) can be easily taken out of the concave portion 4b. It is possible to suppress a decrease in luminous efficiency due to the reflection loss.

  Further, in the light emitting device 10 of the present embodiment, as shown in FIG. 5, the recess 4 b that is recessed from the one surface 4 a of the mounting substrate 4 is a reflective layer that reflects light at least on the inner surface 4 ba that faces the outside of the recess 4 b. 5 may be provided. Thereby, the light-emitting device 10 shown in FIG. 5 suppresses the absorption of light emitted by the second LED chip 21 and the second wavelength conversion layer 22 in the recess 4b, and further suppresses the decrease in the light emission efficiency. It becomes possible. When the reflective layer 5 is conductive, the light emitting device 10 is arranged between the reflective layer 5 and the pair of conductor patterns so that the anode electrode and the cathode electrode of the second LED chip 21 are not short-circuited. An insulating layer (not shown) may be formed as appropriate. Needless to say, the reflective layer 5 may be provided on the tapered portion of the recess 4b.

  For example, when silver plating is used as the reflection layer 5 on the inner side surface 4ba of the recess 4b, the silver plating is applied to blue light emitted from the second LED chip 21 and red light emitted from the second wavelength conversion layer 22. On the other hand, only a reflection loss of about 2% is caused by one reflection.

Furthermore, the light emitting device 10 may be provided with a reflective film (not shown) on the one surface 4a of the mounting substrate 4, and such a reflective film includes light emitted from the first LED chip 11, The light emitted from the phosphor of the first wavelength conversion layer 12 can be efficiently reflected, and specifically, a metal material such as Al, Al alloy, Ag, or Ag alloy, or white such as BaSO ₄ What is necessary is just to comprise using the glass containing the inorganic material used as a pigment. In the light emitting device 10 of the present embodiment, by providing the reflective film, the light emission efficiency of the light emitted from the first wavelength conversion layer 12 and the first LED chip 11 is increased, and in FIG. 2B described above. As explained, secondary absorption in the second wavelength conversion layer 22 by the light reflected by the reflective film can be suppressed.

  The mounting substrate 4 may be configured as an external electrode of the light emitting device 10 by extending a conductor pattern from the one surface 4 a of the mounting substrate 4 to the side surface and the back surface. Such external electrodes of the light emitting device 10 can be electrically connected to a wiring board (not shown) by a reflow process or the like.

  The first and second wavelength conversion layers 12 and 22 used in the present embodiment absorb at least a part of light emitted from the first and second LED chips 11 and 21 that are light emitting elements, respectively, and perform wavelength conversion. The fluorescent light having a peak on the longer wavelength side than the light from the first and second LED chips 11 and 21 is emitted.

  The first wavelength conversion layer 12 absorbs a part of the light emitted from the first LED chip 11 and emits a fluorescent material having a light emission peak at a longer wavelength side, such as an acrylic resin or an epoxy. What is necessary is just to include and form in translucent materials, such as resin, a silicone resin, and glass. The second wavelength conversion layer 22 contains a phosphor that absorbs part of the light emitted from the second LED chip 21 and emits fluorescence having an emission peak on the longer wavelength side. It emits light having a longer wavelength than the fluorescence of one wavelength conversion layer 12. Similarly to the first wavelength conversion layer 12, the second wavelength conversion layer 22 can also contain, for example, a phosphor in a translucent material such as an acrylic resin, an epoxy resin, a silicone resin, or glass. In order to change the light emitted from the light emitting device 10 into white light having high color rendering properties, the first and second LED chips 11 and 21 that emit blue light and the first and second wavelength conversion layers 12 and 22 In this combination, a green phosphor can be used as the phosphor for the first wavelength conversion layer 12, and a red phosphor can be used as the phosphor for the second wavelength conversion layer 22.

  The thicknesses of the first and second wavelength conversion layers 12 and 22 are the target color temperature of the light emitted from the light emitting device 10 and the blue light emitted from the first and second LED chips 11 and 21, respectively. For example, it can be formed to a thickness of about 100 μm, depending on the strength of the phosphor and the phosphor content.

Examples of the phosphor used for the first and second wavelength conversion layers 12 and 22 include aluminum such as Y ₃ Al ₅ O ₁₂ activated by Ce and Tb ₃ Al ₅ O ₁₂ activated by Ce. In addition to nate-based phosphors, silicate-based phosphors such as Eu-activated Ba ₂ SiO ₄ and Eu-activated (SrBa) ₂ SiO ₄ , Eu-activated CaAlSiN ₃ , Eu nitrides such as CaSi ₇ N ₁₀ which is activated by in activated with _Sr 2 _Si 5 _N 8, _Ca were activated by Eu 2 _Si 5 _N 8, Eu in-activated the SrSi ₇ N ₁₀ and Eu It is also possible to employ a phosphor of the system. The phosphors used in the first and second wavelength conversion layers 12 and 22 are not limited to the green phosphor for the first wavelength conversion layer 12 and the red phosphor for the second wavelength conversion layer 22. Even when used as a yellow phosphor for the first wavelength conversion layer 12 and a red phosphor for the second wavelength conversion layer 22, white light can be obtained.

  In addition, in the light-emitting device 10 of this embodiment, although nothing is provided in the 1st LED chip 11 and the 1st wavelength conversion layer 12, the 1st LED chip 11 and the 1st wavelength conversion layer 12 are protected. For the purpose, a sealing member made of a translucent member may be provided.

  Next, the manufacturing process of the light emitting device 10 of this embodiment will be described.

  The first LED chip 11 is flip-chip mounted on the one surface 4 a of the mounting substrate 4 using a plurality of Au bumps 3. Similarly, the second LED chip 21 is flip-chip mounted using a plurality of Au bumps 3 on the inner bottom surface 4bb of the recess 4b recessed from the one surface 4a of the mounting substrate 4. Prior to flip chip mounting, the first and second LED chips 11, 21 are each formed with a first wavelength conversion layer 12 on the first LED chip 11, and on the second LED chip 21. A second wavelength conversion layer 22 is formed. As a method for forming the first and second wavelength conversion layers 12 and 22, a film-like sheet (size: about 1 mm square, thickness of about 1 mm square) filled with a phosphor using a silicone resin as a translucent member as a binder. 100 μm) may be adhered to the sapphire substrate of the LED chip 1 with a translucent adhesive.

  Thereby, the first LED chip 11 mounted on the one surface 4 a of the mounting substrate 4 is loaded with the first wavelength conversion layer 12 containing the green phosphor on the first LED chip 11. Similarly, in the second LED chip 21 mounted on the inner bottom surface 4bb of the recess 4b, the second wavelength conversion layer 22 containing a red phosphor is stacked on the second LED chip 21.

  In addition, the depth of the recess 4 b that is recessed from the one surface 4 a of the mounting substrate 4 is greater than the thickness of the long wavelength light emitting unit 2. The light emitting device 10 houses the second wavelength conversion layer 22 and the second LED chip 21 in the recess 4b, so that the short wavelength light emitting unit 1 and the long wavelength light emitting unit 2 are the first wavelength conversion layer. A line segment connecting any one point of the end face 12a on the second wavelength conversion layer 22 side that emits light from the outside to the outside and an arbitrary point on the surface that emits light from the second wavelength conversion layer 22 to the outside. Are disposed so as to intersect with the one surface 4 a of the mounting substrate 4.

  Such a recess 4b of the mounting substrate 4 may be formed simultaneously with the formation of the mounting substrate 4, or may be formed by excavation or the like after the flat mounting substrate 4 is formed.

  In addition, after mounting the 1st and 2nd LED chip 11 and 21 on the mounting substrate 4, the light transmission which contains a fluorescent substance on the 1st and 2nd LED chip 11 and 21 using a screen printing method The first and second wavelength conversion layers 12 and 22 can also be formed by applying a functional member, respectively. Further, after the first and second LED chips 11 and 21 are mounted on the mounting substrate 4, a light-transmitting light containing a phosphor on the first and second LED chips 11 and 21 using the ink jet printing method. It is also possible to form the first and second wavelength conversion layers 12 and 22 by discharging the property member.

(Embodiment 2)
In this embodiment, the mounting substrate 4 on which the short wavelength light emitting unit 1 and the long wavelength light emitting unit 2 in the light emitting device 10 of the first embodiment shown in FIG. In particular, the light-emitting device 10 of the present embodiment includes a second light-transmissive member 7 that covers the long-wavelength light-emitting portion 2 housed in the recess 4b as shown by the light-emitting device 10 in FIG. 1 is divided into the first translucent member 6 that covers the entire one surface 4 a of the mounting substrate 4 including 1, and the refractive index of the second translucent member 7 is changed to the refractive index of the first translucent member 6. Lower material is used. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted suitably.

  Hereinafter, the light-emitting device 10 of this embodiment will be described with reference to schematic cross-sectional views shown in FIGS.

  In the light emitting device 10 shown in FIG. 6 of the present embodiment, the first LED chip 11 that emits blue light uses a plurality of Au bumps 3 on the conductor pattern (not shown) of the one surface 4a of the mounting substrate 4. The second LED chip 21 that emits blue light is flip-chip mounted on the conductor pattern (not shown) of the inner bottom surface 4bb of the recess 4b of the mounting substrate 4 by using a plurality of Au bumps 3. ing. On the first LED chip 11, a first wavelength conversion comprising a translucent resin layer containing a green phosphor that absorbs part of the blue light from the first LED chip 11 and emits green fluorescence. Layer 12 is formed. Similarly, the second LED chip 11 in the recess 4b of the mounting substrate 4 contains a red phosphor that absorbs a part of the blue light from the second LED chip 21 and emits red fluorescence. A second wavelength conversion layer 22 made of a light resin layer is formed. Thereby, in this light-emitting device 10, the 1st LED chip 11 and the 1st wavelength conversion layer 12 which emits the green fluorescence on the 1st LED chip 11 are used as the short wavelength light emission part 1, and the 2nd LED chip 21 And the 2nd wavelength conversion layer 22 which emits the red fluorescence on the 2nd LED chip 21 is comprised as the long wavelength light emission part 2. FIG.

  In addition, the light emitting device 10 allows the short wavelength light emitting unit 1 and the long wavelength light emitting unit 2 to emit any light from the first wavelength conversion layer 12 to the outside on the end surface 12a on the second wavelength conversion layer 22 side. At least a part of a line segment connecting one point and any one point on the surface that emits light from the second wavelength conversion layer 22 to the outside is arranged so as to intersect with the one surface 4 a of the mounting substrate 4.

  In the light emitting device 10 of the present embodiment, in particular, the first LED chip 11 and the first wavelength conversion layer 12 are covered with the first translucent member 6, and the second LED chip 21 and the second wavelength conversion are covered. The layer 22 is covered with the second translucent member 7. In the light emitting device 10, the refractive index of the first light transmissive member 6 is larger than the refractive index of the second light transmissive member 7 and is in contact with the second light transmissive member 7.

  As a result, the light emitting device 10 fluoresces from the first wavelength conversion layer 12 on the first LED chip 11 mounted on the one surface 4a of the mounting substrate 4 as shown in FIG. Can be suppressed from being incident on the second light-transmissive member 7 in the recess 4b, and a decrease in luminous efficiency associated with secondary absorption in the second wavelength conversion layer 22 can be suppressed. it can.

  For example, in the light emitting device 10, among the green light emitted from the first wavelength conversion layer 12 formed on the first LED chip 11, a part of the green light is directed to the concave portion 4 b side of the mounting substrate 4. However, the light emitting device 10 covers the second wavelength conversion layer 22 with the second light transmissive member 7 having a relatively lower refractive index than the first light transmissive member 6. The ratio of light reflection due to the difference in refractive index at the interface between the translucent member 6 and the second translucent member 7 increases. Thereby, the light-emitting device 10 is suppressed from entering green light into the second wavelength conversion layer 22, suppresses secondary absorption by the second wavelength conversion layer 22, and further suppresses a decrease in light emission efficiency. Is possible.

  The first and second translucent members 6 and 7 cover the first and second LED chips 11 and 21 and the first and second wavelength conversion layers 12 and 22, respectively. A light-transmitting material that is suitably used for protecting against force and having high light-transmitting property in the visible range can be preferably used. Examples of specific materials for the first and second translucent members 6 and 7 include silicone resin, acrylic resin, epoxy resin, and glass, and have a refractive index suitable for the portion to be used. What is necessary is just to employ | adopt material suitably. For example, the epoxy resin can have a refractive index of 1.55 to 1.61, and the silicone resin can have a refractive index of 1.35 to 1.53.

  When a silicone resin is used as the first and second translucent members 6, 7, a phenyl silicone resin is used as the first translucent member 6, and a fluorine-based resin is used as the second translucent member 7. By using the silicone resin, the refractive index of the first translucent member 6 can be made higher than the refractive index of the second translucent member 7.

  The first and second translucent members 6 and 7 are, for example, first formed into the second translucent member 7 after the short wavelength light emitting unit 1 and the long wavelength light emitting unit 2 are formed on the mounting substrate 4 respectively. A fluorine-based silicone resin material is filled so as to surround the long-wavelength light emitting portion 2 mounted on the inner bottom surface 4bb of the recess 4b, and is cured by heating. Next, the short-wavelength light emitting unit 1 and the second translucent member are formed on the mounting substrate 4 on which the second translucent member 7 is formed by using a phenyl silicone resin material that becomes the first translucent member 6. 7 may be applied and heat-cured.

  Further, as in the light-emitting device 10 shown in FIG. 8, the refractive index is larger than that of the second light-transmissive member 7 at the interface between the first light-transmissive member 6 and the second light-transmissive member 7. A third light transmissive member 8 having a refractive index smaller than that of the first light transmissive member 6 may be provided.

  By providing such a third translucent member 8, the first translucent member 6 and the third translucent member 8 are not reflected at the interface between the first wavelength conversion layer 12 and the first translucent member 8. Light can be reflected at the interface between the third translucent member 8 and the second translucent member 7. Therefore, the light emitting device 10 further suppresses light from the first wavelength conversion layer 12 that travels from the first light transmissive member 6 to the second light transmissive member 7 as a whole, and suppresses a decrease in light emission efficiency. It becomes possible.

  Further, in each of the translucent members 6, 7, and 8, light from the first and second LED chips 11 and 21 and light from the first and second wavelength conversion layers 12 and 22 are scattered and mixed. For the purpose of improving the property, a diffusing material may be contained. In particular, as in the light emitting device 10 shown in FIG. 9, the light of the long wavelength light emitting unit 2 is diffused from the concave portion 4 b of the mounting substrate 4 by including the diffusing material 9 in the second light transmissive member 7. Compared with the light emitting device 10 that does not contain the diffusing material 9, the light distribution of the light emitted from the recess 4 b is further expanded and the color mixing property of the light emitted from the light emitting device 10 is further promoted. Is possible.

  Examples of the material of the diffusing material 9 include inorganic materials such as aluminum oxide, silica, and titanium oxide, organic materials such as fluorine-based resins, and organic-inorganic hybrids in which organic components and inorganic components are combined at the molecular level and particle level. The average particle size may be appropriately selected from several μm to several tens of μm, for example.

  In addition, in order to form the 2nd translucent member 7 containing the diffusing material 9, the diffusing material 9 is dispersed and contained in advance in the translucent material of the second translucent member 7 before curing. The light-transmitting material in which the diffusing material 9 is dispersed may be filled in the concave portion 4b of the mounting substrate 4 on which the long wavelength light emitting portion 2 is disposed and heat cured.

DESCRIPTION OF SYMBOLS 1 Short wavelength light emission part 2 Long wavelength light emission part 3 Au bump 4 Mounting board | substrate 4a One surface 4b Recessed part 4ba Inner side surface 4bb Inner bottom surface 5 Reflective layer 6 First translucent member 7 Second translucent member 8 Third Translucent member 9 Diffusing material 10 Light emitting device 11 First LED chip (first light emitting element)
12 1st wavelength conversion layer 12a End surface 21 2nd LED chip (2nd light emitting element)
22 Second wavelength conversion layer

Claims (6)

  A first light-emitting element mounted on one surface of the mounting substrate, and a first wavelength converter that is provided on the first light-emitting element and absorbs at least part of light from the first light-emitting element to emit fluorescence. A second light-emitting element mounted on an inner bottom surface of a recess recessed from the one surface of the mounting substrate, and the second light-emitting element provided in the recess and on the second light-emitting element A second wavelength conversion layer that absorbs at least part of the light from the first wavelength conversion layer and emits fluorescence having a longer wavelength than the fluorescence of the first wavelength conversion layer, and transmits light from the first wavelength conversion layer to the outside At least a part of a line segment connecting an arbitrary point on the end surface on the second wavelength conversion layer side that radiates to the surface and an arbitrary point on the surface that radiates light from the second wavelength conversion layer to the outside. A light-emitting device that intersects with the one surface of the substrate.   The light emitting device according to claim 1, wherein the concave portion has a tapered portion that extends from the inner bottom surface toward the outside of the concave portion.   The light-emitting device according to claim 1, wherein the concave portion is provided with a reflective layer that reflects light at least on an inner surface facing the outside of the concave portion.   The first light emitting element and the first wavelength conversion layer are covered with a first light transmissive member, and the second light emitting element and the second wavelength conversion layer are a second light transmissive member. And the first translucent member has a higher refractive index than the second translucent member and is in contact with the second translucent member. The light-emitting device according to claim 1.   The interface between the first translucent member and the second translucent member has a refractive index larger than that of the second translucent member, and is refracted more than the first translucent member. The light-emitting device according to claim 4, wherein a third translucent member having a low rate is provided.   The light emitting device according to claim 4, wherein a diffusion material is dispersed in the second light transmissive member.

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