JP2007103901A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a color irregularity by disposing, in piles on a light extraction side of an LED element, a sheet-like color conversion member which is excited by a light emitted from the LED element, and emits a light different from the luminescent color of the LED element. <P>SOLUTION: A light emitting device has the LED element 1 in which a light emitting unit 3 having a laminate structure of an n-type semiconductor layer 31, a light emitting layer 32, and a p-type semiconductor layer 33 is prepared in a conductive substrate 2 as a support substrate, and in which the conductive substrate 2 is opaque to the light emitted from the light emitting layer 32; a sheet-like wavelength conversion member (color conversion member) 5 which is disposed in piles on the light extraction side 1a of the LED element 1, excited by the light emitted from the LED element 1, and emits a light different from the emission peak wavelength of the LED element; and a packaging substrate 10 in which an LED unit A configured by the LED element 1 and the wavelength conversion member 5 are mounted in one front surface side. The wavelength conversion member 5 is formed in the substantially the same flat surface size as the LED element 1, and is adhered to the light extraction side 1a of the LED element 1 by using light-transmissive materials, such as a silicone resin, etc. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting device.

  Conventionally, an LED chip that employs a nitride compound semiconductor material as the material of the light emitting layer and a recess that houses the LED chip are formed on one surface, and the LED chip is mounted facing the inner bottom surface of the recess. A phosphor that emits light having a light emission peak wavelength different from the light emission peak wavelength of the LED chip (that is, light having a color different from the light emission color of the LED chip) excited by light emitted from the mounting substrate and the LED chip. A light emitting device comprising a flat wavelength conversion member (color conversion member) made of a dispersed resin molded product and capable of obtaining mixed color light from light emitted from an LED chip and light color-converted by the color conversion member Has been proposed (see, for example, Patent Document 1).

Here, the LED chip described in Patent Document 1 is a blue LED chip or an ultraviolet LED chip, and is one surface side of a crystal growth substrate made of a sapphire substrate that is transparent to light emitted from the light emitting layer. A light emitting portion having a stacked structure of an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer is formed using an epitaxial growth technique, and the light emitting portion is opposed to the inner bottom surface of the recess of the mounting substrate. By flip-chip mounting, the other surface of the crystal growth substrate is used as a light extraction surface. Further, in the light emitting device described in Patent Document 1, the color conversion member is disposed so as to close the recess on the one surface side of the mounting substrate, and the LED chip and the color conversion member are separated from each other. Yes.
JP 2005-228996 A

  By the way, although the light emitted from the light emitting layer of the LED chip is emitted substantially isotropically, in the light emitting device described in Patent Document 1, a part of the light emitted from the light emitting layer is a crystal growth substrate. Difference between the light passing through the crystal growth substrate and entering the color conversion member and the light entering the color conversion member without passing through the crystal growth substrate. The light intensity of the light incident on the light incident surface in the color conversion member is not uniform in the surface, the ratio of the light from the LED chip and the light from the phosphor varies depending on the location of the color conversion member, Color unevenness occurred. Further, in the light emitting device described in Patent Document 1, even if the light is emitted from the light emitting layer and passes through the crystal growth substrate, the light emitted from the other surface of the crystal growth substrate and the crystal growth substrate A light intensity difference and an optical path length difference are generated between the light emitted from the side surfaces of the light source, and the light intensity difference and the optical path length difference also cause color unevenness.

  The present invention has been made in view of the above-described reasons, and an object thereof is to provide a light-emitting device capable of reducing color unevenness.

  According to the first aspect of the present invention, a light-emitting portion having a stacked structure of an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer is provided on a support substrate, and the support substrate is opaque to light emitted from the light-emitting layer. An LED element, and a sheet-like color conversion member that is arranged on the light extraction surface of the LED element and is excited by light emitted from the LED element and emits light of a color different from the emission color of the LED element It is characterized by becoming.

  According to this invention, since the support substrate in the LED element is opaque to the light emitted from the light emitting layer, it is possible to prevent the light emitted from the light emitting layer from passing through the support substrate and reaching the color conversion member. In addition, a sheet-like color conversion member that is excited by the light emitted from the LED element and emits light of a color different from the emission color of the LED element is disposed to overlap the light extraction surface of the LED element. Therefore, the optical path length difference of the light incident on the light incident surface of the color conversion member can be reduced, and the light intensity of the light incident on the light incident surface of the color conversion member becomes substantially uniform in the surface. Can be reduced. Moreover, since the planar size of the color conversion member can be reduced, the material cost of the color conversion member can be reduced, and the cost can be reduced. Furthermore, since the size of the light source composed of the LED element and the color conversion member is equal to the planar size of the LED element, for example, the light emitted from the light source composed of the LED element and the color conversion member is collected. It is possible to further reduce the spot diameter when the light is condensed by the lens.

  According to a second aspect of the present invention, in the first aspect of the invention, the color conversion member is a phosphor that is excited by light emitted from the LED element and emits light having a color different from the emission color of the LED element. It consists of the molded product of the added translucent resin.

  According to this invention, as compared with the case where a light-transmitting resin in which a phosphor is dispersed is applied to the light extraction surface of the LED element, variation in the concentration of the phosphor can be reduced and color unevenness can be reduced.

  According to a third aspect of the present invention, in the first aspect of the invention, the color conversion member is a phosphor that is excited by light emitted from the LED element and emits light having a color different from the emission color of the LED element. It consists of a molded product of added glass.

  According to this invention, compared with the invention of Claim 2, the heat resistance and moisture resistance of the color conversion member can be increased, and the reliability is improved.

  According to a fourth aspect of the invention, in the first aspect of the invention, the color conversion member is a phosphor that is excited by light emitted from the LED element and emits light having a color different from the emission color of the LED element. It is characterized by comprising an added semiconductor substrate.

  According to this invention, compared with the invention of Claim 2, the heat resistance and moisture resistance of the color conversion member can be increased, and the reliability is improved.

  According to a fifth aspect of the present invention, in the first aspect, the color conversion member is excited by light emitted from the LED element, and emits light of a color different from the emission color of the LED element. It consists of the glass substrate which adhere | attached the fluorescent substance layer which adheres to the surface by the side of the said LED element.

  According to this invention, compared to the invention of claim 2, the heat resistance and moisture resistance of the color conversion member can be improved, the reliability is improved, and the color is improved as compared with the inventions of claims 2 and 3. Unevenness can be reduced.

  According to a sixth aspect of the present invention, in the first to fifth aspects of the invention, the LED element has a fine uneven structure for suppressing total reflection of light emitted from the light emitting layer on the light extraction surface. It is characterized by becoming.

  According to the present invention, it is possible to suppress the total reflection of light caused by the difference in refractive index between the light emitting unit and the medium existing on the opposite side of the light emitting unit from the support substrate side, thereby increasing the light extraction efficiency. Color unevenness can be further reduced.

  According to a seventh aspect of the present invention, in the first to sixth aspects of the invention, the color conversion member is formed with a concavo-convex structure for suppressing total reflection on a light emitting surface opposite to the LED element side. It is characterized by.

  According to the present invention, it is possible to suppress the total reflection of light caused by the difference in refractive index between the medium existing on the light exit surface side of the color conversion member and the color conversion member, and to increase the light extraction efficiency. In addition, color unevenness can be further reduced.

  According to an eighth aspect of the present invention, in the first to seventh aspects of the invention, in the LED element, the support substrate is made of a conductive substrate, the conductive substrate constitutes one electrode, and the other electrode is the electrode. The light-emitting part is formed on the opposite side of the light-emitting part on the opposite side of the light-emitting part, and the color conversion member has an exposed part that exposes the surface of the other electrode. It is characterized by.

  According to this invention, after the color conversion member is placed on the LED element, the bonding wire can be bonded to the other electrode.

  The invention according to claim 9 is the invention according to claim 8, wherein the LED element is a transparent electrode in which the other electrode is transparent with respect to light emitted from the light emitting layer, and the color conversion member is exposed. The through-hole is a through-hole penetrating in the thickness direction, and the through-hole is sealed by a color conversion portion made of a material having the same refractive index as that of the color conversion member after bonding of the thin metal wire to the transparent electrode. It is characterized by that.

  According to the present invention, the light emitted from the light emitting layer and directed to the other electrode passes through the other electrode and enters the color conversion unit to be color-converted. Therefore, a portion corresponding to the other electrode is provided. Color unevenness can be reduced while preventing local darkening.

  The invention according to claim 10 is the invention according to claim 8, wherein the exposed portion of the color conversion member is a through-hole penetrating in the thickness direction, and the LED element is located at a central portion of the other electrode. A protruding projecting portion is provided, and after the color conversion member is placed on the light extraction surface, a thin metal wire is bonded to the tip surface of the projecting portion.

  According to this invention, the fine metal wire that is electrically connected to the other electrode is bonded to the tip surface of the projecting portion provided at the center of the other electrode, so that the color conversion member is connected to the LED. It is possible to prevent the adhesive from scooping up to the bonding surface of the fine metal wire in the other electrode when the element is fixed to the element with the adhesive, and the bonding failure of the fine metal wire can be reduced.

  According to an eleventh aspect of the present invention, in any of the eighth to tenth aspects of the present invention, the conductive substrate is a metal substrate.

  According to this invention, the light radiated | emitted from the said light emitting layer to the said electroconductive board | substrate side can be reflected by the metal substrate which is the said electroconductive board | substrate, and light extraction efficiency can be improved.

  The invention according to claim 1 has an effect of reducing color unevenness.

(Embodiment 1)
As shown in FIG. 1, the light emitting device according to the present embodiment has a rectangular plate-like conductive substrate 3 (this embodiment) having a laminated structure of an n-type semiconductor layer 31, a light-emitting layer 32, and a p-type semiconductor layer 33. In the embodiment, the LED element 1 provided on the metal substrate 2 is disposed so as to overlap the LED element 1 opaque to the light emitted from the light emitting layer 32 and the light extraction surface 1a of the LED element 1. LED formed by a sheet-like wavelength conversion member 5 that is excited by light emitted from 1 and emits light having an emission peak wavelength different from the emission peak wavelength of the LED element 1, and the LED element 1 and the wavelength conversion member 5 The unit A includes a rectangular plate-shaped mounting substrate 10 mounted on one surface side. Here, the wavelength conversion member 5 is formed in substantially the same plane size as the LED element 1, and is fixed to the light extraction surface 1 a of the LED element 1 using a translucent material such as silicone resin. In the present embodiment, the conductive substrate 2 constitutes a support substrate, and the wavelength conversion member 5 is excited by the light emitted from the LED element 1 and emits light having a color different from the emission color of the LED element 1. The color conversion member is configured.

  The LED element 1 is a blue LED element that employs an InGaN-based material as a crystal material of the light emitting layer 32 and emits blue light, and is a conductive substrate (this embodiment) that also serves as one electrode (an anode electrode in this embodiment). Then, on the metal substrate 2, light emission having a stacked structure of a p-type semiconductor layer 31 made of a p-type GaN-based material, a light-emitting layer 32 made of an InGaN-based material, and an n-type semiconductor layer 33 made of an n-type GaN-based material. A portion 3 is provided, and the other electrode (a cathode electrode in this embodiment) 4 is formed on the central portion of the light emitting portion 3. In short, the other electrode (hereinafter referred to as a surface-side electrode) 4 is formed in a size smaller than the planar size of the light emitting unit 3. Here, the planar shape of the light emitting unit 3 is rectangular, and the planar shape of the light emitting unit 3 is circular. Further, the front-side electrode 4 is configured by a transparent electrode that is transparent to the light emitted from the light emitting layer 32. Each of the p-type semiconductor layer 31, the light emitting layer 32, and the n-type semiconductor layer 33 may have a single layer structure or a multilayer structure.

As a material of the metal substrate constituting the conductive substrate 2, for example, a metal material having excellent conductivity and thermal conductivity such as Ag, Cu, Au, Al, W, Rh, Mo may be adopted. The substrate 2 may be composed of a metal substrate and a metal thin film (for example, an In thin film or a Sn thin film) formed on the metal substrate. The conductive substrate 2 includes a semiconductor substrate made of a semiconductor material such as Si, GaN, SiC, or ZnO, and a metal thin film (for example, an In thin film or an Sn thin film) formed on the semiconductor substrate. May be. The cathode electrode 4 is composed of a transparent electrode, as the material of the transparent electrode, for _{example, ITO, SnO 2, TiO 2} , ZnO, may be employed as _{an In} 2 O 3 -ZnO based material.

  In the LED element 1, a buffer layer made of a GaN-based material, an n-type semiconductor layer 33, a light emitting layer 32, and a p-type semiconductor layer 31 are epitaxially grown on one surface side of a crystal growth substrate (for example, sapphire substrate, SiC substrate, etc.). The light emitting unit 3 having a stacked structure of the n-type semiconductor layer 33, the light-emitting layer 32, and the p-type semiconductor layer 31 on the one surface side of the crystal growth substrate is sequentially grown by a method (for example, MOVPE method or the like). After that, the light emitting unit 3 and the metal substrate 2 are joined, then the crystal growth substrate is removed from the light emitting unit 3, and then the surface side electrode 4 is formed on the light emitting unit 3. Here, when removing the crystal growth substrate from the light emitting section 3, the buffer layer is thermally decomposed by irradiating the buffer layer with laser light from the other surface side of the crystal growth substrate through the crystal growth substrate. (The substrate temperature at the time of peeling may be set as appropriate within a temperature range of 30 ° C. to 100 ° C., for example), and then the Ga lump remaining on the surface of the n-type semiconductor layer 33 is acidified. Etching and removal may be performed with a chemical of the system.

  In the present embodiment, the n-type semiconductor layer 33, the light-emitting layer 32, and the p-type semiconductor layer 31 are grown in this order when the light-emitting portion 3 is grown, but the p-type semiconductor layer 31, the light-emitting layer 32, and the n-type semiconductor layer 31 are grown. The semiconductor layers 33 may be grown in this order. In this case, the conductive substrate 2 constituting the support substrate also serves as the cathode electrode, and the surface-side electrode 4 constitutes the anode electrode. Further, the crystal material of the light emitting layer 3 is not limited to the InGaN-based material, and for example, an AlInGaN-based material, an AlInN-based material, an AlGaN-based material, or the like may be adopted, and the composition ratio of the group 3 element may be set as appropriate. Alternatively, the emission color can be set to a desired color by appropriately doping an n-type impurity such as Si, Ge, S, or Se or a p-type impurity such as Zn or Mg.

  Further, the mounting substrate 10 described above has conductor patterns 13 and 14 for feeding power to the LED element 1 formed on the insulating layer 12 on the rectangular metal plate 11, and one electrode of the LED element 1 is formed on the mounting layer 10. The conductive substrate 2 also serving as one conductor pattern 13 is joined and electrically connected, and the surface side electrode 4 of the LED element 1 is connected via a bonding wire 7 made of a metal fine wire (for example, a gold fine wire, an aluminum fine wire, etc.). It is electrically connected to the other conductor pattern 14. Here, the LED element 1 and the conductive substrate 2 may be joined using, for example, lead-free solder such as AuSn or SnAgCu. In this embodiment, Cu is used as the material of the metal plate 11. However, the material of the metal plate 11 may be a metal material having a relatively high thermal conductivity, and is not limited to Cu, and Al or the like is used. May be.

The wavelength converting member 5 is a phosphor that emits light of a color different from the emission color of the LED element 1 when excited by the light emitted from the LED element 1 (in this embodiment, it emits broad yellow light). It is composed of a molded product of a translucent material (for example, translucent resin such as silicone resin) to which a yellow phosphor is added, and the thickness is substantially constant. By adopting such a wavelength conversion member 5, it is possible to reduce the variation in the concentration of the phosphor as compared with the case where a light-transmitting resin in which the phosphor is dispersed is applied to the light extraction surface 1a of the LED element 1. Color unevenness can be reduced. Here, the translucent material used as the material of the wavelength conversion member 5 is not limited to the silicone resin, and may be other translucent resin such as an acrylic resin or an epoxy resin, or may employ glass or the like. When glass is employed, the heat resistance and moisture resistance of the wavelength conversion member 5 can be increased and reliability is improved as compared with the case where a translucent resin is employed. Further, the wavelength conversion member 5 may be a semiconductor substrate to which a phosphor is added (for example, a semiconductor substrate transparent to light emitted from the LED element 1 such as a GaN substrate, a SiC substrate, a ZnO substrate). Also, heat resistance and moisture resistance can be improved, and reliability is improved. Examples of yellow phosphors include alkaline earth silicate phosphors such as Ba ₂ SiO _4, aluminate phosphors such as Y ₃ Al ₅ O _12, and Faro such as Ca ₂ BO ₃ Cl _2. A borate phosphor may be used.

  In the LED unit A composed of the LED element 1 and the wavelength conversion member 5 described above, the blue light emitted from the LED element 1 and the light emitted from the yellow phosphor are emitted through the light exit surface of the wavelength conversion member 5. As a result, white light can be obtained. In addition, the combination of the emission color of the LED element 1 and the emission color of the phosphor is not particularly limited. For example, the phosphor used for the wavelength conversion member 5 is not limited to the yellow phosphor, for example, a red phosphor and When used in combination with the green phosphor, white light with high color rendering can be obtained. Further, white light can be obtained even when an LED element that emits ultraviolet light is employed as the LED element 1 and a red phosphor, a green phosphor, and a blue phosphor are used in combination as the phosphor.

  By the way, as for the wavelength conversion member 5, the through-hole 5a penetrated in the thickness direction as an exposed part which exposes the surface side electrode 4 of the LED element 1 is formed. The opening shape of the through-hole 5 a is a circular shape that is slightly larger than the planar shape of the surface-side electrode 4. Here, the wavelength conversion member 5 is thicker than the surface side electrode 4, and the LED unit A in which the wavelength conversion member 5 is placed on the LED element 1 is bonded to the surface side electrode 4. After bonding 7, the through-hole 5 a is sealed with a color conversion portion 6 made of a translucent material (for example, silicone resin) in which the same phosphor as the wavelength conversion member 5 is dispersed. Therefore, in the light emitting device of the present embodiment, the light emitted from the color conversion unit 6 is also white light similar to the light emitted from the wavelength conversion member 5, and the part corresponding to the surface side electrode 4 is locally darkened. It is possible to reduce color unevenness while preventing the occurrence of the above. Here, the color conversion unit 6 is preferably formed of a material having the same refractive index as that of the wavelength conversion member 5 serving as a color conversion member. However, with respect to the refractive index of the color conversion unit 6, the same refractive index as that of the wavelength conversion member 5 is a reflection loss compared to the case where the refractive index of the color conversion unit 6 completely matches the refractive index of the wavelength conversion member 5. If the refractive index is within a range that falls within 0.1%, the refractive index is considered to be the same as that of the wavelength conversion member 5. For example, the refractive index of the wavelength conversion member 5 is 1.5, and the refractive index of the color conversion unit 6 is in the range of 1.434 to 1.566 (that is, the target refractive index is within the range of ± 4.4%). If so, the reflection loss at one interface between the wavelength conversion member 5 and the color conversion unit 6 can be made within 0.05%, and the total reflection loss at the two interfaces can be made within 0.1%. can do. In the light emitting device in which the LED unit A is mounted on the mounting substrate 10 as described above, the electric path of the conductor pattern 13-the conductive substrate 2-the light emitting part 3-the surface side electrode 4-the bonding wire 7-the conductor pattern 14 is formed. Therefore, by applying a voltage between the conductor patterns 13 and 13 so that a forward bias voltage is applied between the anode electrode and the cathode electrode of the LED element 1, the blue light is emitted from the LED element 1. Is emitted, and blue light and yellow light are emitted from the wavelength conversion member 5 and the color conversion unit 6 respectively.

  Hereinafter, a method for manufacturing the above-described light-emitting device will be described with reference to FIGS.

  First, as shown in FIG. 2A, the LED element 1 and the wavelength conversion member 5 are prepared, and then an adhesive composed of a gel-like silicone resin is dropped on the light extraction surface 1 a of the LED element 1. The wavelength conversion member 5 is placed on the light extraction surface 1a side of the LED element 1 and the LED element 1 and the wavelength conversion member 5 are fixed to obtain the structure shown in FIG.

  Thereafter, the LED unit A is fixed on the mounting substrate 10 (in this embodiment, on the above-described conductor pattern 13), and then the surface-side electrode 4 of the LED element 1 and the conductor pattern 14 of the mounting substrate 10 are bonded to the bonding wire 7. The structure shown in FIG. 2 (c) is obtained by electrically connecting via.

  Subsequently, by filling the through hole 5a of the wavelength conversion member 5 with a translucent material to which the same phosphor as the wavelength conversion member 5 is added and curing the translucent material, the color conversion unit 6 is formed. The light emitting device having the structure shown in FIG.

  In the light emitting device of the present embodiment described above, since the conductive substrate 2 in the LED element 1 is opaque to the light emitted from the light emitting layer 32, the light emitted from the light emitting layer 32 passes through the conductive substrate 2. And the sheet-like wavelength conversion member 5 is arranged so as to overlap the light extraction surface 1a of the LED element 1, so that the light incident on the wavelength conversion member 5 can be prevented. The difference in the optical path length of the light incident on the surface can be reduced, and the light intensity of the light incident on the light incident surface in the wavelength conversion member 5 becomes substantially uniform in the surface, so that color unevenness can be reduced. In addition, the wavelength conversion member 5 only needs to be provided directly above the light extraction surface 1a of the LED element 1, and may be the same size as the planar size of the LED element 1, so that the concave portion of the mounting substrate as in Patent Document 1 above. Compared with the wavelength conversion member having a planar size that closes the portion, the planar size of the wavelength conversion member 5 can be reduced, so that there is an advantage that the material cost of the wavelength conversion member 5 can be reduced and the cost can be reduced. Further, in the light emitting device of the present embodiment, since the conductive substrate 2 described above is composed of a metal substrate, the light emitted from the light emitting layer 32 to the conductive substrate 2 side is conducted directly under the light emitting unit 3. Can be reflected by the conductive substrate 2, and the light extraction efficiency can be increased. Moreover, in the light-emitting device of this embodiment, since the size of the light source comprised by the LED element 1 and the wavelength conversion member 5 becomes equivalent to the planar size of the LED element 1, for example, the LED element 1 and the wavelength conversion member 5 It is possible to make the spot diameter smaller when the light emitted from the light source constituted by is condensed by the condenser lens.

  Further, in the light emitting device of the present embodiment, the sealing material (for example, silicone resin, acrylic resin) that seals the LED unit A and the bonding wire 7 electrically connected to the LED unit A on the one surface side of the mounting substrate 10. A convex lens-shaped lens portion made of resin or the like may be provided, and the light extraction efficiency can be increased by providing the lens portion. Here, the sealing material is preferably a material that is transparent to the light emitted from the LED unit A and has a refractive index equivalent to the refractive index of the wavelength conversion member 5. By adopting such a material, the wavelength can be reduced. The light reflected at the interface between the conversion member 5 and the lens portion can be reduced, and the light extraction efficiency can be improved.

(Embodiment 2)
The basic configuration of the light emitting device of the present embodiment is substantially the same as that of the first embodiment, and as shown in FIG. 3, the total reflection of light emitted from the light emitting layer 32 is suppressed on the light extraction surface 1 a of the LED element 1. The difference is that a fine relief structure is formed. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  Here, the fine concavo-convex structure formed on the light extraction surface 1a of the LED element 1 has a V-shaped concave section whose opening width is gradually narrowed in the depth direction along the thickness direction of the light emitting section 3 in a one-dimensional cycle. Although it is formed to have a structure, it may be formed to have a two-dimensional periodic structure. Such a fine concavo-convex structure may be formed using, for example, a laser processing technique, an etching technique, an imprint lithography technique, or the like.

What is necessary is just to set suitably the period of the fine concavo-convex structure formed in the light extraction surface 1a of the LED element 1 in the range of 1/4 to 100 times the peak wavelength λ of the light emitted from the light emitting layer 32 of the light emitting unit 3, For example, when the period d (see FIG. 3B) of the fine concavo-convex structure is set in the range of λ / 4 to λ, the first medium (here, the n-type semiconductor layer 33 in the light emitting unit 3) The refractive index of the n-type GaN-based material is n ₁ , and an adhesive layer made of a silicone resin that is interposed between the light emitting unit 3 and the wavelength conversion member 5 in this case, in contact with the n-type semiconductor layer 33. ) Is n ₂ , the width of the first medium in the left-right direction in FIG. 3B is a, the width of the second medium is b, and the effective refractive index near the fine concavo-convex structure with respect to the TE wave is < If n _E >, the effective refractive index <n _E > near the fine concavo-convex structure is expressed by the following formula. You can.

Similarly, if the effective refractive index in the vicinity of the fine concavo-convex structure with respect to the TM wave is <n _M >, the effective refractive index <n _M > can be expressed by the following formula.

Here, as can be seen from the above formulas 1 and 2, in the LED unit A of the present embodiment, the above-described effective refractive indexes <n _E > and <n _M > are similar to those of the light emitting unit 3 in the vicinity of the fine concavo-convex structure. Since it gradually changes along the thickness direction and becomes an intermediate value between the media on both sides of the light extraction surface 1a of the LED element 1, the intermediate refraction between the first medium and the second medium. This is equivalent to interposing a thin film layer having a refractive index, so that total reflection due to the difference in refractive index between the first medium and the second medium can be reduced, and the light extraction efficiency can be increased.

  Further, when the period d of the fine concavo-convex structure is set in the range of 2λ to 4λ, for example, the wave optical effect, that is, the light reflected from the critical angle or more can be extracted by using the diffracted light. The take-out efficiency is improved.

  Further, when the period d of the fine concavo-convex structure is set within a range of 5λ to 100λ, for example, the geometric effect, that is, the incident angle to the interface between the first medium and the second medium is less than the critical angle. By increasing the surface area, the total reflection due to the difference in refractive index between the first medium and the second medium can be reduced, and the light extraction efficiency is improved.

  Thus, in the light emitting device of the present embodiment, as described above, the light extraction surface 1a of the LED element 1 is formed with the fine concavo-convex structure that suppresses the total reflection of the light emitted from the light emitting layer 32. The light caused by the difference in refractive index between the medium (the second medium) that is opposite to the conductive substrate 2 side in the light emitting unit 3 and the n-type semiconductor layer 33 (the first medium) in the light emitting unit 3. Total reflection can be suppressed, light extraction efficiency can be increased, and color unevenness can be further reduced. Further, if a fine concavo-convex structure is also formed at the formation site of the surface-side electrode 4 in the n-type semiconductor layer 33, the entire difference due to the refractive index difference between the n-type semiconductor layer 33 and the surface-side electrode 4 made of a transparent electrode. Reflection can be reduced, light extraction efficiency can be increased, and color unevenness can be further reduced.

  As shown in FIG. 4, a fine concavo-convex structure having a shape matching the fine concavo-convex structure formed on the light extraction surface 1 a of the LED element 1 may be formed on the LED element 1 side of the wavelength conversion member 5. Here, in order to form the fine concavo-convex structure on the wavelength conversion member 5, for example, a laser processing technique or an imprint lithography technique may be used. Further, when there is a difference in refractive index between the wavelength conversion member 5 and the medium that is in contact with the surface (light emitting surface) opposite to the LED element 1 side in the wavelength conversion member 5, the LED conversion element 5 side in the wavelength conversion member 5. The light extraction efficiency can be increased by forming the same fine concavo-convex structure (the concavo-convex structure for suppressing total reflection) on the surface opposite to the surface.

(Embodiment 3)
The basic configuration of the light emitting device of the present embodiment is substantially the same as that of the first embodiment, and as shown in FIG. 5, a protruding portion 4b is provided at the central portion of the surface-side electrode 4 as compared with other portions. The difference is that a bonding wire 7 made of a fine metal wire is bonded to the tip surface of the projecting portion 4b. Here, the surface side electrode 4 in the present embodiment is composed of a transparent electrode 4b and a projecting part 4b made of a conductive film (for example, an Al film, a transparent conductive film, etc.) formed on the central part of the transparent electrode 4b. It is configured. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  By the way, in the light-emitting device of Embodiment 1 or Embodiment 2, although the surface side electrode 4 is comprised by the transparent electrode and the surface of the said transparent electrode is a joining surface of the bonding wire 7, the wavelength conversion member which is a color conversion member When 5 is fixed to the LED element 1 with an adhesive, the adhesive may crawl up to the surface of the surface side electrode 4 (bonding surface of the bonding wire 7) and the surface may be contaminated by the adhesive. If the bonding surface of the bonding wire 7 in the surface side electrode 4 is contaminated, it causes a decrease in yield due to bonding failure.

  On the other hand, in the light emitting device of the present embodiment, the bonding wire 7 electrically connected to the surface side electrode 4 is bonded to the tip surface of the projecting portion 4b provided at the center of the surface side electrode 4. Therefore, when the wavelength conversion member 5 is fixed to the LED element 1 with an adhesive, the adhesive can be prevented from creeping up to the bonding surface of the bonding wire 7 in the surface side electrode 4, and bonding defects of the bonding wire 7 can be reduced. can do. The surface-side electrode 4 is not limited to a two-layer structure, but may be a single-layer structure processed into a convex shape.

(Embodiment 4)
The basic configuration of the light emitting device of the present embodiment is substantially the same as that of the first embodiment. As shown in FIG. 6, the structure of the mounting substrate 10 and the LED unit A and the LED unit A on the one surface side of the mounting substrate 10 are electrically connected. The difference is that a convex lens-shaped lens portion 20 made of a sealing material (for example, silicone resin, acrylic resin, etc.) that seals the bonding wires 7 and 7 that are connected to each other is provided. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  The mounting substrate 10 in the present embodiment includes a rectangular plate-shaped heat transfer plate 15 made of a heat conductive material and mounted on the LED unit A via a submount member 40 for thermal stress relaxation, and one surface of the heat transfer plate 15. And a rectangular plate-like wiring board 16 stacked on the side (the upper surface side in FIG. 6). Here, the wiring substrate 16 is provided with a pair of lead patterns 17 and 18 for supplying power to the LED unit A on the surface side opposite to the heat transfer plate 15 side, and at a portion corresponding to the submount member 40 in the thickness direction. A rectangular window hole 16 a penetrating the LED board 1 is formed, and heat generated in the LED element 1 and the wavelength conversion member 5 of the LED unit A is transferred to the submount member 40 and the heat transfer plate 21 without passing through the wiring board 16. Being heated. As the above-described heat conductive material, Cu is adopted, but not limited to Cu, for example, Al may be adopted. Further, as the insulating base material of the wiring board 16, a glass epoxy board using FR4 is adopted, and each lead pattern 17, 18 includes a Cu film formed on one surface side of the glass epoxy board and a Ni film. It is comprised by the laminated film of a film | membrane and an Ag film | membrane. Note that a metal film 19 for preventing warpage is formed on the other surface side of the wiring board 16, and the heat transfer plate 15 and the wiring board 16 are fixed using a sheet-like adhesive film (not shown). However, when the material of each of the warp preventing metal film 16 and the heat transfer plate 15 is Cu, it can be fixed without using an adhesive film. The material of the insulating base material of the wiring board 16 is not limited to a glass epoxy resin such as FR4, and may be, for example, a polyimide resin or a phenol resin.

  Further, the LED unit A is formed in a rectangular plate shape having a plane size larger than the plane size of the conductive substrate 2 and works on the LED unit A due to a difference in linear expansion coefficient between the LED unit A and the heat transfer plate 15. It is mounted on the heat transfer plate 15 via the above-described submount member 40 that relieves stress.

  The submount member 40 has not only a function of relieving the stress but also a heat conduction function of transferring heat generated in the LED unit A to a range wider than the planar size of the LED unit A in the heat transfer plate 15. Yes. In the present embodiment, AlN having a relatively high thermal conductivity and insulating properties is employed as the material of the submount member 40, and the submount member 40 is joined to the conductive substrate 2 serving also as the one electrode of the LED element 1 to be electrically The conductor pattern 41 to be connected is formed. Thus, in the LED unit A, the conductive substrate 2 is electrically connected to one lead pattern 17 via the conductor pattern 41 and the bonding wire 7 provided on the submount member 40, and the surface side electrode 4 is different from the other. It is electrically connected to the other lead pattern 18 via the bonding wire 7. The conductive substrate 2 of the LED unit A and the submount member 40 may be bonded using, for example, solder such as SnPb, AuSn, SnAgCu, or silver paste, but lead-free solder such as AuSn, SnAgCu. It is preferable to join using. The thickness dimension of the submount member 40 is set so that the surface of the conductor pattern 41 is farther from the heat transfer plate 15 than the one surface of the wiring board 16.

  Further, in the LED element 1 according to the present embodiment, the surface-side electrode 4 is configured by a laminated film of a Ni film and an Au film, and is formed around the light emitting unit 3. On the other hand, the wavelength conversion member 5 that is a color conversion member has a cutout portion 5 c formed at an area corresponding to the front surface side electrode 4 as an exposed portion that exposes the front surface side electrode 4 of the LED element 1. Therefore, also in the present embodiment, the bonding wire 7 can be bonded to the surface side electrode 4 after the wavelength conversion member 5 is placed on the LED element 1 in an overlapping manner. In addition, the surface side electrode 4 formed in the peripheral part of the light emitting part 3 is only the part which becomes a pad among the cathode electrodes of the LED element 1, and the surface of the current density of the current flowing through the light emitting part 3 other than the pad. By providing a current spreading pattern portion on the surface of the light emitting portion 3 for improving the inner uniformity, the color variation can be further reduced.

  In the light emitting device of the present embodiment described above, similarly to the first embodiment, the conductive substrate 2 in the LED element 1 is opaque to the light emitted from the light emitting layer 32, so that the light emitted from the light emitting layer 32 is not emitted. Since it can prevent passing through the conductive substrate 2 to reach the wavelength conversion member 5, and the sheet-like wavelength conversion member 5 is disposed so as to overlap the light extraction surface 1 a of the LED element 1, Since the optical path length difference of the light incident on the light incident surface of the wavelength conversion member 5 can be reduced and the light intensity of the light incident on the light incident surface of the wavelength conversion member 5 becomes substantially uniform in the surface, color unevenness Can be reduced.

  Further, in the light emitting device of the present embodiment, heat generated in the LED unit A is transferred to the submount member 40 and the heat transfer plate 21 without passing through the wiring board 16, so that heat dissipation is improved as compared with the first embodiment. And since the temperature rise of the junction temperature of the LED element 1 can be suppressed, the input power can be increased and the light output can be increased. Moreover, since the temperature rise of the fluorescent substance in the wavelength conversion member 5 is also suppressed, the fall of the luminous efficiency of a fluorescent substance can be suppressed.

  Further, the light emitting device of the present embodiment includes the convex lens-shaped lens portion 20 in which the LED unit A and the bonding wires 7 and 7 are sealed on the one surface side of the mounting substrate 10 described above. Can be increased.

  Note that the light-emitting device of this embodiment may be provided with the fine uneven structure described in Embodiment 2 as appropriate. In the first to third embodiments, the same lens unit 20 as that of the light emitting device of the present embodiment may be provided.

(Embodiment 5)
The basic configuration of the light emitting device of the present embodiment is substantially the same as that of the fourth embodiment. As shown in FIG. 7, the wavelength conversion member 5 that is a sheet-like color conversion member is excited by light emitted from the LED element 1. The LED substrate 1 is different from the LED device 1 in that the phosphor layer 52 made of a phosphor that emits light of a color different from that of the LED element 1 is formed on the surface of the LED element 1. Here, the phosphor layer 52 may be formed on the surface of the glass substrate 51 by, for example, sputtering. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 4, and description is abbreviate | omitted.

  Thus, in the light emitting device of this embodiment, the heat resistance of the wavelength conversion member 5 is higher than that in the case where the wavelength conversion member 5 is formed of a translucent resin molded product to which a phosphor is added as in the first embodiment. And moisture resistance can be improved, and reliability is improved. Moreover, color unevenness can be reduced compared with the case where the fluorescent substance is added to the translucent material like Embodiment 1-4.

  Note that the light-emitting device of this embodiment may be provided with the fine uneven structure described in Embodiment 2 as appropriate.

1 is a schematic cross-sectional view of a light emitting device in Embodiment 1. FIG. It is explanatory drawing of the manufacturing method of the light-emitting device same as the above. The light-emitting device in Embodiment 2 is shown, (a) is a schematic sectional drawing, (b) is principal part explanatory drawing. It is principal part sectional drawing of the other structural example same as the above. 6 is a schematic cross-sectional view of a light emitting device in Embodiment 3. FIG. It is a schematic sectional drawing of the light-emitting device in Embodiment 4. 6 is a schematic cross-sectional view of a light emitting device according to Embodiment 5. FIG.

Explanation of symbols

1 LED element 1a Light extraction surface 2 Conductive substrate (support substrate)
3 Light emitting part 4 Electrode (surface side electrode)
4a Transparent electrode 4b Projecting part 5 Wavelength conversion member (color conversion member)
5a Through hole (exposed part)
6 Color conversion unit 7 Bonding wire (fine metal wire)
DESCRIPTION OF SYMBOLS 10 Mounting board 13 Conductor pattern 14 Conductor pattern 31 P-type semiconductor layer 32 Light emitting layer 33 N-type semiconductor layer A LED unit

Claims (11)

  a light-emitting portion having a stacked structure of an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer is provided on a support substrate, and the support substrate is opaque to light emitted from the light-emitting layer; A light emitting device comprising: a sheet-like color conversion member disposed on the light extraction surface and excited by light emitted from the LED element to emit light of a color different from the light emission color of the LED element. apparatus.   The color conversion member is formed of a translucent resin molded article to which a phosphor that is excited by light emitted from the LED element and emits light having a color different from the emission color of the LED element is added. The light-emitting device according to claim 1.   The color conversion member is formed of a glass molded article to which a phosphor that is excited by light emitted from the LED element and emits light having a color different from the emission color of the LED element is added. Item 2. The light emitting device according to Item 1.   2. The color conversion member is formed of a semiconductor substrate to which a phosphor that is excited by light emitted from the LED element and emits light of a color different from the emission color of the LED element is added. The light emitting device described.   The color conversion member adheres a phosphor layer made of a phosphor that is excited by light emitted from the LED element and emits light of a color different from the emission color of the LED element to the surface on the LED element side. The light emitting device according to claim 1, comprising a glass substrate.   6. The LED device according to any one of claims 1 to 5, wherein a fine concavo-convex structure that suppresses total reflection of light emitted from the light emitting layer is formed on the light extraction surface. The light emitting device according to 1.   7. The color conversion member according to claim 1, wherein an uneven structure for suppressing total reflection is formed on a light emitting surface opposite to the LED element side. Light-emitting device.   In the LED element, the support substrate is made of a conductive substrate, the conductive substrate constitutes one electrode, and the other electrode is on the side opposite to the support substrate side from the light emitting unit. 8. The method according to claim 1, wherein the color conversion member is formed with an exposed portion that exposes a surface of the other electrode. 9. Light-emitting device.   In the LED element, the other electrode is a transparent electrode that is transparent to the light emitted from the light emitting layer, and the color conversion member is a through-hole through which the exposed portion penetrates in the thickness direction. 9. The light emitting device according to claim 8, wherein the hole is sealed by a color conversion portion made of a material having the same refractive index as that of the color conversion member after bonding of the thin metal wire to the transparent electrode.   The exposed portion of the color conversion member is a through-hole penetrating in the thickness direction, and the LED element is provided with a protruding base portion that protrudes from a central portion of the other electrode as compared with other portions, and the color conversion 9. The light emitting device according to claim 8, wherein a metal thin wire is bonded to the tip end surface of the projecting portion after the member is disposed so as to overlap the light extraction surface. The light emitting device according to claim 8, wherein the conductive substrate is made of a metal substrate.

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