JP2013175527A - Semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light emitting device which enables a phosphor having characteristics deteriorated at high temperature to be used even when having a structure achieving good luminous efficiency.SOLUTION: Transparent translucent members 17 coat LED dies 16 so as to form dome like shapes. Further, a reflection frame 12 enclosing the translucent members 17 is located at a peripheral part of a circuit board 13 and a fluorescent plate 11 covers upper parts of the translucent members 17 while being supported by the reflection frame 12. While high luminous efficiency is maintained by the dorm like translucent members 17 and the reflection frame 12, heat of the LED dies 16 is not directly transmitted to the fluorescent plate 11. Thus, temperature rise of the phosphor is suppressed.

Description

  The present invention relates to a semiconductor light emitting device that converts the wavelength of light emitted from a semiconductor light emitting element using a phosphor.

  A semiconductor light emitting device (hereinafter referred to as an LED die unless otherwise specified) cut from a wafer is mounted on a lead frame or a circuit board and covered with a translucent member such as resin or glass and packaged (hereinafter referred to as a light emitting device). Unless otherwise specified, it is called an LED device). Although this LED device takes various forms depending on the application, in order to improve the light emission efficiency, the outer shape of the translucent member covering the LED die may be formed into a bullet shape or a dome shape.

  For example, FIG. 1 of Patent Document 1 shows an illumination light source (LED device) in which the outer shape of a resin 300 (translucent member) is formed in a dome shape. FIG. 1 of Patent Document 1 will be described again in FIG. FIG. 5 is a sectional view showing a part of a sectional structure of a conventional LED device (illumination light source). The illumination light source (LED device) in FIG. 5 includes a substrate 100, a semiconductor light emitting element 200 (LED die) mounted on the substrate 100, and a resin 300 provided in the region of the semiconductor light emitting element 200. The substrate 100 is obtained by covering the upper surface of the metal base 100a with an insulating layer 100b and has a recess Cav. The semiconductor light emitting element 200 is die-bonded to the bottom of the recess Cav, and the semiconductor light emitting element 200 is connected to the wiring pattern conductor 100c by a wire W. In this illumination light source (LED device), the resin 300 disperses and holds phosphors that absorb blue light from the semiconductor light emitting element 200 and emit yellow light.

  Although not explicitly disclosed in Patent Document 1, when the LED die is covered with a translucent member in a dome shape, total reflection at the interface between the translucent member and air is less likely to occur, so that the light emission efficiency is improved.

JP 2001-148514 A (FIG. 1)

  In the LED device (illumination light source) shown in FIG. 1 of Patent Document 1, phosphors are dispersedly held in a resin 300. That is, since the phosphor is adjacent to the LED die (semiconductor light emitting element 200), when the LED die emits light, the heat generation causes the phosphor to become high temperature. However, some phosphors have excellent characteristics such as wavelength conversion efficiency at room temperature, but degrade the characteristics as the temperature rises. As a result, when the LED die is covered with a translucent member in a dome shape to increase the light emission efficiency, if the translucent member is dispersed and held, the phosphor becomes hot when the LED device is turned on. Therefore, usable phosphors are limited.

  Accordingly, the present invention has been made in view of the above problems, and provides a semiconductor light emitting device that can use a phosphor that has a structure with good luminous efficiency and that has good characteristics at room temperature and deteriorates characteristics at high temperature. The purpose is to do.

In order to solve the above problems, a semiconductor light-emitting device of the present invention includes a semiconductor light-emitting element, a translucent member that covers the semiconductor light-emitting element, and a phosphor that converts the wavelength of light emitted from the semiconductor light-emitting element. In
The translucent member is transparent, the semiconductor light emitting element is coated in a dome shape,
A reflection frame surrounding the translucent member, and a fluorescent plate that includes the phosphor and covers an upper portion of the translucent member.

  When the semiconductor light-emitting element is covered with a translucent member in a dome shape, the interface between the translucent member and air is curved so as to be convex outward, so that the light is emitted from the semiconductor light-emitting element and becomes a translucent member. The incident light is difficult to totally reflect at the interface with the air. As a result, the light emission efficiency from the translucent member is increased. Further, light that has reached the periphery of the semiconductor light emitting device among the light emitted from the translucent member is reflected by the reflection frame. That is, all light including light reflected by the reflection frame except for loss such as absorption is directed upward to the semiconductor light emitting device and is incident on the fluorescent plate. A part of this light is wavelength-converted, and the semiconductor light emitting device emits light of a color different from the light emission color of the semiconductor light emitting element such as white. At this time, since the semiconductor light emitting element that has become high temperature due to light emission and the fluorescent plate are not adjacent to each other, the phosphor contained in this fluorescent plate requires only a small increase in temperature.

  The fluorescent plate may be supported by the reflection frame.

  A plurality of semiconductor light emitting elements may exist in a region surrounded by the reflection frame, and each of the semiconductor light emitting elements may be individually covered with a dome shape by the light transmissive member.

  The translucent members covered in a dome shape may be separated from each other.

  As described above, the semiconductor light-emitting device of the present invention improves the light extraction efficiency by covering the semiconductor light-emitting element in a dome shape and directing the light directed to the side by the reflection frame upward. The wavelength is converted by the fluorescent plate arranged above. Since this fluorescent plate is not in contact with the semiconductor light emitting device, it does not reach a high temperature. As a result, the semiconductor light emitting device of the present invention can use a phosphor that has a good light emission efficiency but has good characteristics at room temperature and deteriorates characteristics at high temperature.

The external view of the LED device in 1st Embodiment of this invention. Sectional drawing of the LED apparatus shown in FIG. The top view of the state which removed the fluorescent plate from the LED apparatus shown in FIG. Sectional drawing of the LED apparatus in 2nd Embodiment of this invention. Sectional drawing of the conventional LED device.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted. For the sake of explanation, the scale of the members is changed as appropriate. Furthermore, the relationship with the invention specific matter described in the claims is described in parentheses.
(First embodiment)

  The LED device 10 (semiconductor light emitting device) of the first embodiment of the present invention will be described with reference to FIGS. First, the outer shape of the LED device 10 will be described with reference to FIG. FIG. 1 is an outline view of the LED device 10, (a) is a plan view, (b) is a front view, and (c) is a bottom view. When the LED device 10 is viewed from above, a rectangular fluorescent screen 11 can be seen (a). When the LED device 10 is viewed from the front, the reflection frame 12 can be seen under the fluorescent plate 11, and the circuit board 13 can be seen under the reflection frame 12 (b). When the LED device 10 is viewed from the bottom side, the external connection electrodes 14 and 15 can be seen inside the circuit board 13 (c).

  The internal structure of the LED device 10 will be described with reference to FIGS. FIG. 2 is a cross-sectional view of the LED device 10 drawn along the line AA shown in FIG. A reflection frame 12 is installed in the periphery of the circuit board 13. In addition, three LED dies 16 (semiconductor light emitting elements) are mounted on the inner surface of the reflection frame 12 on the upper surface of the circuit board 13, and each LED die 16 has a hemispherical translucency on the upper surface and side surfaces. Covered with a member 17. At this time, the translucent member 17 is separated for each dome-shaped portion, and each translucent member 17 covers one LED die 16. The fluorescent plate 11 is present above the translucent member 17 through an air layer, and this fluorescent plate 11 is supported by the reflection frame 12 in a bonded state.

  FIG. 3 is a plan view showing a state in which the fluorescent plate 11 is removed from the LED device 10 in FIG. The upper surface of the circuit board 13 can be seen in the area inside the rectangular reflection frame 12. In addition, six LED dies 16 are mounted in a region inside the reflection frame 12, and each LED die 16 is located at the bottom of a dome-shaped translucent member 17 that looks substantially circular from the top.

  The circuit board 13 is a so-called double-sided board. The circuit board 13 has mounting electrodes (not shown) and wiring (not shown) on the upper surface, and external connection electrodes 14 and 15 (see FIG. 1C) are formed on the lower surface. ing. The mounting electrodes and wiring and the external connection electrodes 14 and 15 are connected through through holes (not shown). The reflection frame 12 is obtained by kneading and curing reflective fine particles such as titanium oxide and alumina in a silicone resin, and has a width of about 200 to 300 μm and a height of about 600 to 800 μm.

  The LED die 16 is a light emitting diode, and includes a semiconductor layer formed on a transparent substrate such as a sapphire substrate having a thickness of about 80 to 120 μm, and an anode electrode and a cathode electrode on the semiconductor layer. The LED die 16 may be mounted by face-down mounting (also referred to as flip chip mounting) in which an anode electrode and a cathode electrode are directly connected to an electrode formed on the upper surface of the circuit board 13, or a sapphire substrate is mounted on the circuit board 13. Face-up mounting may be used in which the anode electrode and the cathode electrode are connected to an electrode formed on the upper surface of the circuit board 13 by wire by die bonding.

  The translucent member 17 is a transparent silicone resin, and is molded with a mold and separated from each other by etching. Further, the silicone resin is potted in a state where the affinity with the silicone resin in the upper surface region of the circuit board 13 in contact with the bottom surface of the translucent member 17 is increased and the affinity in the peripheral region is lowered, and the surface tension of the silicone resin is utilized. Thus, the shape of the translucent member 17 may be controlled.

  In addition, since each translucent member 17 formed in a dome shape covers the LED die 16 one by one, the dome can be made small, which contributes to the thinning of the LED device 10. That is, even if a plurality of LED dies 16 are mounted to brighten the LED device 10, a dome composed of the translucent member 17 is formed for each LED die 16, so that the dome is reduced in size.

  When the LED die 16 is flip-chip mounted, most of the light incident on the light transmissive member 17 from the LED die 16 passes through the transparent substrate included in the LED die 16. At this time, the refractive index of the translucent member 17 (often around 1.4 to 1.5) is between the refractive index of the transparent substrate (about 1.7 in the case of sapphire) and the refractive index of air. Therefore, the light extraction efficiency is higher when light is emitted into the air via the translucent member 17 than when light is emitted directly from the transparent substrate into the air.

  The fluorescent plate 11 is a silicone resin obtained by kneading and curing a phosphor, and has a thickness of about 100 μm. Since the fluorescent plate 11 is away from the LED die, it is not only less susceptible to the heat generated by the LED die 16 but also color unevenness due to glare (glare) and azimuth angle is reduced.

  Next, the emitted light of the LED device 10 will be described. The light incident on the translucent member 17 from the LED die 16 is curved so that the dome-shaped translucent member 17 is convex outward, and thus reaches the interface between the translucent member 17 and air. When it does, it becomes difficult to totally reflect and it radiate | emits from the translucent member 17 efficiently. Of the light emitted from the translucent member 17, the light reaching the periphery of the LED device 10 is reflected in various directions by the reflection frame 12. Excluding losses such as absorption, this reflected light is directed directly upward or reflected by the surface of the circuit board 13 and finally directed upward of the LED device 10. And this light, the light directly upward from the translucent member 17, and the other light emitted from the translucent member 17 and reflected by a member other than the reflection frame and directed upward are arranged on the upper portion of the translucent member 17. Incident on the fluorescent plate 11.

Part or all of the light incident on the fluorescent plate 11 is wavelength-converted by the phosphor in the fluorescent plate 11. As a result, the LED device 10 emits light in a color different from that of the LED die 16 such as white. As described above, the LED die 16 is heated with light emission. However, since the fluorescent plate 11 is separated from the LED die 16, the temperature rise can be reduced. As a result, it is possible to use a silicate phosphor that has good characteristics at room temperature and remarkably deteriorates at high temperatures.
(Second Embodiment)

  In the LED device 10 shown as the first embodiment, the translucent member 17 covering each LED die 16 in a dome shape is separated. On the other hand, even if the LED die is covered in a dome shape, adjacent dome-shaped portions (hereinafter referred to as dome portions) may be connected at the bottom. Therefore, as a second embodiment of the present invention, an LED device 40 in which the bottoms of adjacent dome parts 18 are connected will be described with reference to FIG.

  FIG. 4 is a cross-sectional view of the LED device 40. The difference between FIG. 4 and FIG. 2 used to explain the LED device 10 of the first embodiment is only that the dome portions 18 of the translucent member 20 in FIG. . When the translucent member 20 is formed by a mold, the dome portions 18 are adjacent to each other at a small distance. In addition, when the connection part 19 exists, it has confirmed that the connection part 19 becomes a light guide and the light which penetrate | invaded the connection part 19 becomes difficult to radiate | emit. When pursuing luminous efficiency, it is better to separate the translucent member 17 as in the LED device 10 (see FIG. 2).

  In the LED devices 10 and 40 according to the first and second embodiments, the translucent members 17 and 20 and the fluorescent plate 11 are separated with air sandwiched therebetween. In order to improve the luminous efficiency while separating the translucent member and the fluorescent plate so as not to raise the temperature of the fluorescent plate, the substance interposed between the translucent member and the fluorescent plate is not limited to air. For example, the substance may be a resin having a smaller refractive index than that of the translucent member and transparent and having a low thermal conductivity. When such a resin is applied or filled so as to cover the dome-shaped translucent member, a fluorescent plate may be attached on the resin, or a fluorescent resin containing a phosphor may be applied on the resin. A fluorescent plate may be formed by curing. A lead frame may be used instead of the circuit board 13.

10, 40 ... LED device (semiconductor light emitting device),
11 ... Fluorescent screen,
12 ... Reflective frame,
13 ... Circuit board,
14, 15 ... external connection electrodes,
16 ... LED die (semiconductor light emitting element),
17, 20 ... translucent member,
18 ... Dome,
19: Connection part.

Claims (4)

In a semiconductor light emitting device comprising: a semiconductor light emitting element; a translucent member that covers the semiconductor light emitting element; and a phosphor that converts the wavelength of light emitted from the semiconductor light emitting element.
The translucent member is transparent, the semiconductor light emitting element is coated in a dome shape,
A semiconductor light emitting device comprising: a reflection frame surrounding the translucent member; and a fluorescent plate including the phosphor and covering an upper portion of the translucent member.   The semiconductor light emitting device according to claim 1, wherein the fluorescent plate is supported by the reflection frame.   3. A plurality of semiconductor light emitting elements are present in a region surrounded by the reflection frame, and each semiconductor light emitting element is individually covered in a dome shape with the light transmissive member. The semiconductor light-emitting device as described.   4. The semiconductor light-emitting device according to claim 1, wherein translucent members that are covered in a dome shape are separated from each other.

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