JP2008159706A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device capable of preventing a visible light emitted using a phosphor having an emission peak wavelength on a low wavelength side from being absorbed by a phosphor having an emission peak wavelength in a long wavelength side when two kinds of phosphors have different emission colors, and suppressing an increase in light extraction loss. <P>SOLUTION: The light-emitting device is provided with a sealing section 50 made of a sealing resin for sealing an LED chip 10 on the mounting surface side of the LED chip 10 in a mounting substrate 20; a dome-like first color converting section 61 made of a red phosphor (first phosphor) to be excited with a blue light emitted from the LED chip 10 for red light emission, and a light-transmissive material; a dome-like second color converting section 62 formed of a green phosphor (second phosphor) to be excited with a blue light emitted from the LED chip 10 for green light emission and a light-transmissive material, and positioned on the outside of the first color converting section 61. The first color converting section 61 is integrated with the second color converting section 62. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting device using an LED chip (light emitting diode chip).

  Conventionally, light emission in which a desired mixed color light (for example, white light) is obtained by combining an LED chip and a phosphor that emits light of a light emission color different from that of the LED chip when excited by light emitted from the LED chip. Research and development of the apparatus is performed in various places (for example, refer to Patent Document 1).

Here, in Patent Document 1, as shown in FIG. 4, an LED chip 10 ′, a mounting substrate 20 ′ on which the LED chip 10 ′ is mounted, and a convex lens-like shape disposed on the LED chip 10 ′. An optical member (light extraction increasing portion) 140 ′, a particulate phosphor that is excited by visible light emitted from the LED chip 10 ′ and emits visible light having a color different from the emission color of the LED chip 10 ′, and a transparent substance And a dome-shaped color conversion member (wavelength conversion member) 160 ′ formed of a light material (for example, silicone resin) and hermetically sealed on the mounting substrate 20 ′ so as to cover the optical member 140 ′. A light emitting device 1 'has been proposed. Here, the mounting substrate 20 ′ is provided with a housing recess 20a ′ for housing a part of the LED chip 10 ′ and the optical member 140 ′ on one surface, and the LED chip 10 ′ is placed in the housing recess 20a ′. Flip chip mounting. The light emitting device 1 ′ having the configuration shown in FIG. 4 includes a sealing portion 50 ′ made of a sealing resin that seals the LED chip 10 ′ stored in the storage recess 20a ′ of the mounting substrate 20 ′. Yes.
JP 2005-158949 A

  By the way, in the light emitting device 1 ′ having the configuration shown in FIG. 4, the red phosphor and the green phosphor are used as the phosphors in the color conversion member 160 ′, so that only the yellow phosphor is used as the phosphor. Although white light with high color rendering properties can be obtained, a part of the green light emitted from the green phosphor is secondarily absorbed by the red phosphor and converted into red light, so that the blue light from the LED chip 10 ' Compared to the case where light is directly converted into red light by a red phosphor, the red light emission efficiency is lowered, and it has been desired to suppress such secondary absorption.

  The present invention has been made in view of the above reasons, and its purpose is to make visible light emitted from a phosphor having an emission peak wavelength on the low wavelength side of two types of phosphors having different emission colors a long wavelength. An object of the present invention is to provide a light emitting device capable of suppressing secondary absorption by a phosphor having an emission peak wavelength on the side and suppressing increase in light extraction loss.

  The invention of claim 1 is an LED chip that emits visible light, a mounting substrate on which the LED chip is mounted, and a sealing resin that seals the LED chip on the mounting surface side of the LED chip on the mounting substrate. A dome-shaped first color conversion unit formed of a first phosphor that is excited by visible light emitted from the LED chip and emits visible light having a wavelength longer than that of the LED chip, and a translucent material; The first phosphor is formed of a second phosphor and a translucent material that are excited by visible light emitted from the LED chip and emit visible light having a longer wavelength than the LED chip and a shorter wavelength than the first phosphor. And a dome-shaped second color conversion unit located outside the color conversion unit, wherein the first color conversion unit and the second color conversion unit are integrated.

  According to this invention, the dome-shaped first color formed by the first phosphor that is excited by the visible light emitted from the LED chip and emits visible light having a wavelength longer than that of the LED chip and the translucent material. Formed by a converter, a second phosphor that is excited by visible light emitted from the LED chip, and emits visible light having a longer wavelength than the LED chip and a shorter wavelength than the first phosphor, and a translucent material And a dome-shaped second color conversion unit located outside the first color conversion unit, so that the lower wavelength side of the two types of phosphors of the first phosphor and the second phosphor It is possible to suppress the secondary absorption of the visible light emitted from the second phosphor having the emission peak wavelength at the second wavelength into the first phosphor having the emission peak wavelength on the long wavelength side. 1 color conversion unit and 2nd color conversion unit integrated Because it is, it is possible to suppress an increase in the light extraction loss as compared with the case where there is an air layer between the first color conversion unit and the second color conversion unit.

  According to a second aspect of the present invention, in the first aspect of the invention, the second color conversion unit and the first color conversion unit are integrally formed.

  According to this invention, it is possible to prevent a gap from being formed between the second color conversion unit and the first color conversion unit, and it is possible to more reliably suppress an increase in light extraction loss. .

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the first color conversion portion and the sealing portion are in close contact with the sealing portion and between the first color conversion portion. A dome-shaped optical member disposed on the mounting surface side of the mounting substrate in a form in which an air layer is formed is provided.

  According to this invention, visible light scattered by the first phosphor in the first color conversion unit and visible light emitted from the first phosphor are prevented from returning to the sealing unit. The light extraction efficiency to the outside can be improved.

  According to the first aspect of the present invention, visible light emitted from a second phosphor having a light emission peak wavelength on the lower wavelength side of the two types of phosphors of the first phosphor and the second phosphor having different emission colors. Can be suppressed from being absorbed by the first phosphor having the emission peak wavelength on the long wavelength side.

(Embodiment 1)
As shown in FIG. 1, the light emitting device 1 of the present embodiment includes an LED chip 10 that emits visible light, a mounting substrate 20 on which the LED chip 10 is mounted, and a mounting surface side of the LED chip 10 on the mounting substrate 20. And a first phosphor that emits visible light having a wavelength longer than that of the LED chip 10 when excited by the visible light emitted from the LED chip 10. And a dome-shaped first color conversion unit 61 formed of a translucent material, and a longer wavelength than the LED chip 10 and a shorter wavelength than the first phosphor when excited by visible light emitted from the LED chip 10 A dome-shaped second color conversion unit 62 that is formed of a second phosphor that emits visible light and a translucent material and is located outside the first color conversion unit 61.

  In the light emitting device 1 of the present embodiment, a GaN blue LED chip that emits blue light is used as the LED chip 10, and the blue light emitted from the LED chip 10 is used as the first phosphor of the first color conversion unit 61. Is used as a second phosphor of the second color conversion unit 62 and is excited by the blue light emitted from the LED chip 10 to emit green light. Using the particulate green phosphor, blue light emitted from the LED chip 10 and transmitted through the sealing unit 50, the first color conversion unit 61 and the second color conversion unit 62, and the red color of the first color conversion unit 61 White light composed of mixed light of red light emitted from the phosphor and transmitted through the second color converter 62 and green light emitted from the green phosphor of the second color converter 62 can be obtained.

  The LED chip 10 has an anode electrode (not shown) formed on one surface side (the lower surface side in FIG. 1) in the thickness direction and a cathode electrode (shown on the upper surface side in FIG. 1) in the other thickness direction. The other surface side is the light extraction surface 11 side, but blue light is also emitted from the side surface. Here, the anode electrode and the cathode electrode are formed of a laminated film of a lower layer Ni film and an upper layer Au film.

  The mounting substrate 20 includes a submount member 30 on which the LED chip 10 is mounted on one surface side, and a rectangular plate-shaped heat transfer plate that is formed of a heat conductive material and is fixed to the central portion on the one surface side. 21 and a flexible printed wiring board having a rectangular plate shape that is fixed to one surface side (the upper surface side in FIG. 1) of the heat transfer plate 21 via, for example, a polyolefin-based fixing sheet (not shown). The wiring board 22 has a rectangular window hole 24 through which the mount member 30 is exposed. Therefore, the heat generated in the LED chip 10 is transferred to the submount member 30 and the heat transfer plate 21 without passing through the wiring board 22.

  The heat transfer plate 21 is based on a metal plate 21a made of Cu, and a coating film 21b made of an Au film is formed on both surfaces in the thickness direction of the metal plate 21a.

  On the other hand, the wiring substrate 22 is provided with a pair of wiring patterns 23 and 23 for feeding power to the LED chip 10 on one surface side of an insulating base material 22a made of a polyimide film. A resist layer 26 made of a white resin covering a portion where the wiring patterns 23, 23 are not formed in the conductive base material 22a is laminated. Here, in the LED chip 10, the cathode electrode is electrically connected to one wiring pattern 23 via the bonding wire 14, and the anode electrode is connected to the other via the electrode pattern 31 of the submount member 30 and the bonding wire 14. The wiring pattern 23 is electrically connected. Each of the wiring patterns 23 and 23 is formed in an outer peripheral shape slightly smaller than half of the outer peripheral shape of the insulating base material 22a. Further, FR4, FR5, paper phenol or the like may be employed as the material of the insulating base material 22a.

  The resist layer 26 is patterned so that two portions of each wiring pattern 23, 23 are exposed in the vicinity of the window hole 24 of the wiring substrate 22 and one portion of each wiring pattern 23, 23 is exposed in the peripheral portion of the wiring substrate 22. In each wiring pattern 23, 23, a portion exposed in the vicinity of the window hole 24 of the wiring substrate 22 constitutes a terminal portion 23 a to which the bonding wire 14 is connected, and a circle exposed at the peripheral portion of the wiring substrate 22. The part of the shape constitutes an electrode part 23b for external connection. In addition, the wiring patterns 23 and 23 of the wiring board 22 are comprised by the laminated film of Cu film | membrane, Ni film | membrane, and Au film | membrane, and the uppermost layer is Au film | membrane.

  The submount member 30 is made of AlN having a relatively high thermal conductivity and electrical insulation, and has a planar size larger than the chip size of the LED chip 10. A stress relieving function that relieves stress acting on the LED chip 10 due to a difference in linear expansion coefficient with the LED chip 10, and heat generated in the LED chip 10 in a range wider than the chip size of the LED chip 10 in the heat transfer plate 21 It has a heat conduction function to transfer heat to the. Therefore, in the light emitting device 1 of the present embodiment, the stress acting on the LED chip 10 due to the difference in linear expansion coefficient between the LED chip 10 and the heat transfer plate 21 can be relieved, and the heat generated in the LED chip 10 can be reduced. Can be efficiently radiated through the submount member 30 and the heat transfer plate 21.

  In the present embodiment, AlN having a relatively high thermal conductivity and insulating properties is adopted as the material of the submount member 30, but the material of the submount member 30 is not limited to AlN, for example, composite SiC, Si Etc. may be adopted. Further, the electrode pattern 31 is formed on one surface side of the submount member 30 to be joined to the anode electrode that is an electrode on the submount member 30 side of the LED chip 10, and the LED pattern 31 is surrounded by the LED pattern 31. A reflective film 32 that reflects light emitted from the side surface of the chip 10 is formed. Therefore, visible light radiated from the side surface of the LED chip 10 can be prevented from being absorbed by the submount member 30, and the light extraction efficiency to the outside can be further increased. Here, the electrode pattern 31 is formed of an alloy of Au and Sn containing Au as a main component (for example, 80Au-20Sn, 70Au-30Sn, etc.). The reflective film 32 is made of Al, but is not limited to Al, and may be made of Ag, Ni, Au, or the like.

  In the light emitting device 1 of the present embodiment, the thickness dimension of the submount member 30 is set so that the surface of the submount member 30 is farther from the heat transfer plate 21 than the surface of the resist layer 26 of the wiring board 22. In addition, light emitted from the LED chip 10 to the side can be prevented from being absorbed by the wiring board 22 through the inner peripheral surface of the window hole 24 of the wiring board 22.

  As the sealing resin that is the material of the sealing portion 50 described above, a silicone resin is used. However, the sealing resin is not limited to a silicone resin, and for example, an epoxy resin may be used.

  The first color conversion unit 61 uses a mixed material in which a particulate red phosphor that is excited by blue light emitted from the LED chip 10 and emits red light is dispersed in a translucent material such as silicone resin. It is formed in a dome shape. Here, in this embodiment, since the silicone resin is adopted as the translucent material of the first color conversion unit 61, the refractive index difference and the linear expansion coefficient difference between the first color conversion unit 61 and the sealing unit 50 are used. Can be reduced. In addition, when the material of the sealing part 50 is an epoxy resin, it is preferable that the 1st color conversion part 61 is also formed with an epoxy resin.

  The second color conversion unit 62 is a mixed material in which a particulate green phosphor that emits green light when excited by blue light emitted from the LED chip 10 is dispersed in a translucent material such as silicone resin. Is formed in a larger dome shape than the first color conversion unit 61.

  In addition, the translucent material used as the material of the first color conversion unit 61 and the second color conversion unit 62 is not limited to a silicone resin. Organic / inorganic hybrid materials mixed and bound together in the above may be employed. Further, the first color conversion unit 61 and the second color conversion unit 62 are formed so as to have a uniform thickness. In addition, the first color conversion unit 61 and the second color conversion unit 62 have, for example, an adhesive (for example, a silicone resin, an epoxy resin, or the like) with respect to the mounting substrate 20 at the end edge (periphery of the opening) on the mounting substrate 20 side. ) May be used.

  In the light emitting device 1 of the present embodiment described above, a dome formed of a red phosphor and a translucent material that is excited by blue light emitted from the LED chip and emits red light having a longer wavelength than the LED chip 10. First-color conversion unit 61, a green phosphor that emits green light having a longer wavelength than LED chip 10 and a shorter wavelength than red phosphor when excited by blue light emitted from LED chip 10 and light transmission The dome-shaped second color conversion unit 62 that is formed of a luminescent material and is located outside the first color conversion unit 61 is provided, so that a low level of two types of phosphors, a red phosphor and a green phosphor. It becomes possible to suppress secondary absorption of green light emitted from the green phosphor having the emission peak wavelength on the wavelength side into the red phosphor having the emission peak wavelength on the long wavelength side. Moreover, in the light emitting device 1 of the present embodiment, the first color conversion unit 61 and the second color conversion unit 62 are integrated, so that the dome in which the sealing unit 50 is formed inside as shown in FIG. An air layer 70 is formed between the optical member 40, the first color conversion unit 61, and the first color conversion unit 61, and air is formed between the first color conversion unit 61 and the second color conversion unit 62. As compared with the case where the layer 80 is formed, an increase in light extraction loss can be suppressed.

  Here, in the light emitting device 1 of the present embodiment, the second color conversion unit 62 and the first color conversion unit 61 are integrally formed, so that the second color conversion unit 62 and the first color conversion unit 61 are between them. It is possible to prevent a gap from being formed in the light source, and to more reliably suppress an increase in light extraction loss. The first color conversion unit 61 and the second color conversion unit 62 may be integrated using a transparent adhesive (for example, a silicone resin). A plurality of types of second color conversion units 62 having different body densities are prepared, and the color mixture emitted through the first color conversion unit 61 before the second color conversion unit 62 is bonded to the first color conversion unit 61. If light is detected and the second color conversion unit 62 having an appropriate concentration is bonded to the first color conversion unit 61 according to the detection result, color variations among the light emitting devices 1 can be reduced. Further, in the light emitting device 1 of the present embodiment, the refractive index of the translucent material (medium) containing the green phosphor in the second color conversion unit 62 includes the red phosphor in the first color conversion unit 61. The translucent material (silicone resin in this embodiment) of each of the first color conversion unit 61 and the second color conversion unit 62 is selected so that the refractive index of the translucent material (medium) is larger. For example, the green light radiated from the green phosphor of the second color conversion unit 62 can be prevented from entering the first color conversion unit 61.

(Embodiment 2)
The basic configuration of the light emitting device 1 of the present embodiment is substantially the same as that of the first embodiment, and is in close contact with the sealing portion 50 between the first color conversion portion 61 and the sealing portion 50 as shown in FIG. The difference is that a dome-shaped optical member 40 is provided on the mounting surface side of the mounting substrate 20 in such a manner that an air layer 70 is formed between the first color conversion unit 61 and the first color conversion unit 61. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  The optical member 40 is a molded product of a translucent material (for example, silicone resin) and is formed in a dome shape. Here, in this embodiment, since the optical member 40 is formed of silicone resin, the difference in refractive index and the linear expansion coefficient between the optical member 40 and the sealing portion 50 can be reduced. In addition, when the material of the sealing part 50 is an epoxy resin, it is preferable that the optical member 40 is also formed of an epoxy resin.

  Therefore, in the light emitting device 1 of the present embodiment, the blue light scattered by the red phosphor in the first color conversion unit 61 and the red light emitted from the red phosphor are prevented from returning to the sealing unit 50. The light extraction efficiency to the outside can be improved.

  In each of the above embodiments, visible light emitted from the LED chip 10 is blue light, visible light emitted from the first phosphor in the first color conversion unit 61 is red light, and in the second color conversion unit 62. Although the case where the visible light emitted from the second phosphor is green light is exemplified, the color of each visible light is not particularly limited.

1 is a schematic cross-sectional view of a light emitting device according to Embodiment 1. FIG. It is a schematic sectional drawing of the light-emitting device of the comparative example same as the above. 6 is a schematic cross-sectional view of a light emitting device according to Embodiment 2. FIG. It is a schematic sectional drawing of the light-emitting device of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light-emitting device 10 LED chip 11 Light extraction surface 20 Mounting board 40 Optical member 50 Sealing part 61 1st color conversion part 62 2nd color conversion part 70 Air layer

Claims (3)

  An LED chip that emits visible light, a mounting substrate on which the LED chip is mounted, a sealing portion made of a sealing resin that seals the LED chip on the mounting surface side of the LED chip on the mounting substrate, and radiation from the LED chip A dome-shaped first color converter formed of a first phosphor and a translucent material that is excited by visible light and emits visible light having a longer wavelength than the LED chip, and is emitted from the LED chip A second phosphor that emits visible light having a wavelength longer than that of the LED chip and a wavelength shorter than that of the first phosphor when excited by visible light and a translucent material, and is located outside the first color conversion unit. And a dome-shaped second color conversion unit, wherein the first color conversion unit and the second color conversion unit are integrated.   The light emitting device according to claim 1, wherein the second color conversion unit and the first color conversion unit are integrally formed.   Arranged on the mounting surface side of the mounting substrate in such a manner that an air layer is formed between the first color conversion unit and the sealing unit and in close contact with the sealing unit. The light emitting device according to claim 1 or 2, further comprising a dome-shaped optical member provided.

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