JP2007088095A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device that has high heat radiation properties and reliability, and strong directivity of mixed color light. <P>SOLUTION: The light-emitting device includes a reflector 40 for surrounding an LED chip 10 and bonding wires 14, 14 at the packaging surface side of the LED chip 10 in a packaging substrate 20. A submount member 30 for relaxing stress operating on the LED chip 10 caused by the difference in the coefficient of thermal expansion between the LED chip 10 and a metal plate 21 and thermally combining both of them is interposed between the LED chip 10 and the metal plate 21. An electrode at the side of the submount member 30 in both the electrodes of the LED chip 10 is connected to one bonding wire 14 via a conductive pattern provided at the submount member, and an electrode at a side opposite to the side of the submount member 30 is directly connected to the other bonding wire 14. A sealing section 50 is formed by a silicone resin, contains a yellow phosphor that is excited by light radiated from the LED chip 10 and radiates yellow-based light, and is formed in the shape of a convex lens. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  Conventionally, a metal base plate in which a plurality of LED chips are directly mounted face-up, and a wiring pattern in which both electrodes of each LED chip are connected via bonding wires are stacked on the metal base plate. A wiring board; and a sealing part in which the LED chip and a bonding wire connected to the LED chip are sealed with an epoxy resin on the mounting surface side of the LED chip in the metal base plate, and the sealing part has a convex lens shape. Thus, there has been proposed a light emitting device that has a high directivity (in other words, a small solid angle of light emitted through the sealing portion) (for example, Patent Document 1).

In addition, conventionally, by combining an LED chip that emits blue light or ultraviolet light and a phosphor that emits light of a color different from the emission color of the LED chip by being excited by the light emitted from the LED chip, A technique for obtaining mixed color light having a hue different from the emission color of the LED chip including white is widely known.
JP 2003-152225 A

  However, in the light emitting device described in Patent Document 1, since the LED chip is directly mounted on the metal base plate, the heat dissipation is excellent, but due to the difference in linear expansion coefficient between the metal base plate and the LED chip. As a result, the LED chip may be damaged. In addition, when an epoxy resin is used as the material of the sealing portion, the weather resistance of the sealing portion is low, and the sealing portion deteriorates with time due to light emitted from the LED chip. In the case of a blue LED chip that emits blue light, there is a problem in that the sealing portion tends to deteriorate.

  The present invention has been made in view of the above-described reasons, and an object thereof is to provide a light-emitting device that has high heat dissipation and reliability and strong directivity of mixed color light.

  The invention of claim 1 is an LED chip, a mounting substrate on which the LED chip is mounted, and a reflector that surrounds the LED chip on the mounting surface side of the LED chip on the mounting substrate and reflects light emitted from the LED chip. A reflector having a shape in which an opening area gradually increases as the distance from the mounting surface increases, and a sealing portion that seals the LED chip and a pair of bonding wires that are electrically connected to the LED chip; The substrate is provided with a metal plate and a pair of lead patterns that are electrically connected to both electrodes of the LED chip on the surface opposite to the metal plate side, and a window hole is provided in a portion corresponding to the LED chip. The LED chip is composed of an insulating substrate laminated on a plate, and an LED chip has one electrode formed on one surface side and the other electrode on the other surface side. Is a submount member that relieves stress acting on the LED chip due to a difference in linear expansion coefficient between the LED chip and the metal plate, and is smaller than the chip size of the LED chip. Largely mounted on a metal plate via a submount member that thermally couples the LED chip and the metal plate, and the electrode on the submant member side of both electrodes is connected to one bonding wire via a conductor pattern provided on the submount member. Connected and the electrode on the opposite side of the submount member is directly connected to the other bonding wire, and the sealing portion is formed of silicone resin and excited by light emitted from the LED chip to emit light from the LED chip. It contains a phosphor that emits light of a color different from the color, and is formed into a convex lens shape To.

  According to this invention, the LED chip and the metal plate are submount members that relieve stress acting on the LED chip due to the difference in linear expansion coefficient between the two and have a size that is larger than the chip size of the LED chip. Since a submount member that thermally couples the LED chip and the metal plate is interposed, the heat dissipation is high and the LED chip can be prevented from being damaged due to the difference in linear expansion coefficient. Reliability can be increased. Moreover, since the sealing part which seals an LED chip and each bonding wire in the mounting surface side of the LED chip in a mounting substrate is formed with the silicone resin, it is weatherproof compared with the case where it is formed with an epoxy resin. In addition, the deterioration due to the light emitted from the LED chip is less likely to occur, and the reliability is further enhanced. In addition, since the sealing portion contains a phosphor that is excited by light emitted from the LED chip and emits light of a color different from the emission color of the LED chip, and is formed in a convex lens shape, The directivity of the mixed color light of the light emitted from the LED chip and the light emitted from the phosphor can be enhanced.

  According to the first aspect of the present invention, there is an effect that heat dissipation and reliability are high and the directivity of the mixed color light is strong.

  Hereinafter, the light-emitting device of the present embodiment will be described with reference to FIGS.

  The light emitting device 1 of the present embodiment radiates from the LED chip 10, the LED chip 10, the mounting substrate 20 on which the LED chip 10 is mounted, the LED chip 10 on the mounting substrate 20 side of the mounting substrate 20. A frame-shaped reflector 40 that reflects light, and a sealing portion 50 that seals the LED chip 10 and the bonding wires 14 and 14 connected to the LED chip 10 and has elasticity. The light-emitting device 1 of the present embodiment is used as a light source of a lighting fixture such as a spotlight, for example, and has a metal (for example, Al, Cu or the like having a thermal conductivity through an insulating layer 90 made of a green sheet, for example. By mounting on the device body 100 made of a high metal), the thermal resistance from the LED chip 10 to the device body 100 can be reduced, the heat dissipation is improved, and the temperature rise of the junction temperature of the LED chip 10 can be suppressed. Therefore, the input power can be increased and the optical output can be increased. Here, in the case of a lighting fixture, a plurality of light emitting devices 1 are mounted on the fixture main body 100 so as to obtain a desired light output (in FIG. 5, ten light emitting devices 1 are bottomed). An example is shown in which the inner bottom surface of the bottom wall of the cylindrical instrument body 100 is arranged at equal intervals along the circumferential direction), and a plurality of light emitting devices 1 may be connected in series or in parallel.

  The mounting substrate 20 includes a metal plate 21 on which the LED chip 10 is mounted, and an insulating base material 22 made of a glass epoxy substrate laminated on the metal plate 21, and the metal plate in the insulating base material 22. A pair of lead patterns 23 that are electrically connected to both electrodes (not shown) of the LED chip 10 are provided on the surface opposite to the 21 side, and a window is formed at a portion corresponding to the LED chip 10 in the insulating substrate 22. A hole 24 is provided so that heat generated in the LED chip 10 can be transferred to the metal plate 21 without passing through the insulating base material 22. Here, Cu is employed as the material of the metal plate 21, but any metal material having a relatively high thermal conductivity may be used, and not only Cu but Al or the like may be employed. In addition, the metal plate 21 and the insulating base material 22 are fixed by a fixing material 25 made of an insulating sheet-like adhesive film. Each lead pattern 23 is composed of a laminated film of a Ni film and an Au film, and a portion not covered with the color conversion member 70 is an outer lead portion 23b. Further, the insulating base material 22 is formed with a reflection film 27 that reflects light emitted from the LED chip 10 around the window hole 24. Here, the reflection film 27 is formed of a laminated film of a Ni film and an Ag film.

  The LED chip 10 is a GaN-based blue LED chip that emits blue light, and is a conductive substrate made of an n-type SiC substrate that has a lattice constant and a crystal structure close to GaN as a crystal growth substrate and has conductivity compared to a sapphire substrate. The light-emitting portion 12 is formed of a GaN-based compound semiconductor material on the main surface side of the conductive substrate 11 and has a laminated structure portion having, for example, a double hetero structure. ), A cathode electrode (n electrode) which is a cathode side electrode (not shown) is formed on the back surface of the conductive substrate 11, and is shown on the surface of the light emitting unit 12 (the outermost surface on the main surface side of the conductive substrate 11). An anode electrode (p electrode) which is an electrode on the anode side that is not to be formed is formed. In short, the LED chip 10 has an anode electrode formed on one surface side and a cathode electrode formed on the other surface side. The cathode electrode and the anode electrode are composed of a laminated film of a Ni film and an Au film, but the material of the cathode electrode and the anode electrode is not particularly limited, and a material capable of obtaining good ohmic characteristics For example, Al or the like may be employed. In the present embodiment, the light emitting unit 12 of the LED chip 10 is mounted on the metal plate 21 so as to be on the side farther from the metal plate 21 than the conductive substrate 11. The conductive plate 11 may be mounted on the metal plate 21 so as to be closer to the metal plate 21 than the conductive substrate 11. In consideration of the light extraction efficiency, it is desirable to arrange the light emitting unit 12 on the side away from the metal plate 21, but in this embodiment, the conductive substrate 11 and the light emitting unit 12 have the same refractive index. Therefore, even if the light emitting unit 12 is disposed on the side close to the metal plate 21, the light extraction loss does not become too large.

  Further, the LED chip 10 is formed on the metal plate 21 in the shape of a rectangular plate having a size larger than the chip size of the LED chip 10, and the LED chip 10 is caused by the difference in linear expansion coefficient between the LED chip 10 and the metal plate 21. It is mounted via a submount member 30 that relieves stress acting on the chip 10. The submount member 30 has not only a function of relieving the stress, but also a heat conduction function of transferring heat generated in the LED chip 10 to a range wider than the chip size of the LED chip 10 on the metal plate 21. . In the present embodiment, AlN having a relatively high thermal conductivity and insulation is used as the material of the submount member 30, and the LED chip 10 has the cathode electrode on the LED chip 10 side of the submount member 30. Electrically connected to one lead pattern 23 via a bonding wire 14 provided on the surface and connected to the cathode electrode (see FIG. 2) and a metal wire (for example, a gold wire, an aluminum wire, etc.) The anode electrode is electrically connected to the other lead pattern 23 via the bonding wire 14. The LED chip 10 and the submount member 30 may be bonded using, for example, solder such as SnPb, AuSn, SnAgCu, or silver paste, but may be bonded using lead-free solder such as AuSn, SnAgCu. It is preferable.

  The material of the submount member 30 is not limited to AlN, and any material may be used as long as the linear expansion coefficient is relatively close to 6H—SiC that is the material of the conductive substrate 11 and the heat conductivity is relatively high. Si or the like may be employed.

  A silicone resin is used as the transparent resin material of the sealing portion 50 described above, and the sealing portion 50 is gel-like and has elasticity.

  The reflector 40 has a frame shape opened in a circular shape, and the shape of the inner side surface 40a is designed so that light emitted from the side surface of the LED chip 10 is reflected toward the lens 60 side. That is, the reflector 40 is formed in a shape in which the opening area increases as the distance from the LED chip 10 increases in the thickness direction of the LED chip 10 (that is, the shape in which the opening area gradually increases as the distance from the mounting surface increases). Here, as the material of the reflector 40, a material (for example, Al) having a relatively high reflectance with respect to light emitted from the LED chip 10 (here, blue light) is adopted, and the inner side surface 40a of the reflector 40 is used. What is necessary is just to make it a mirror surface, and the reflector 40 should just be formed, for example by drawing an aluminum base material. In addition, the reflector 40 is fixed to the mounting substrate 20 with a fixing material 26 made of an insulating sheet-like adhesive film.

  By the way, the sealing part 50 contains a particulate yellow phosphor that is excited by blue light emitted from the LED chip and emits broad yellow light. Therefore, in the light emitting device 1 of the present embodiment, the blue light emitted from the LED chip 10 and the light emitted from the yellow phosphor are emitted from the light emitting surface 50a of the sealing unit 50, and white light is emitted. Obtainable. In the present embodiment, the yellow phosphor is contained in the sealing unit 50. However, the phosphor to be contained in the sealing unit 50 is not limited to the yellow phosphor. For example, a red phosphor and a green phosphor are included. Even when mixed, white light can be obtained.

  In addition, the sealing portion 50 is formed in a convex lens shape in which the optical axis coincides with the LED chip 10 and the reflector 40. In the light emitting device 1 of the present embodiment, the light emitting surface of the sealing portion 50 is formed in a convex curved surface shape that does not totally reflect at the boundary between the light emitting surface and the air, and thus emitted from the LED chip 10. Light (light emitted from the LED chip 10 and reaching the light emitting surface 50a of the sealing portion 50 without being reflected by the reflector 40) and light emitted from the LED chip 10 and reflected by the inner side surface 40a of the reflector 40 and reflected by the light emitting surface 50a Can be easily emitted without being totally reflected at the boundary between the light emitting surface 50a and the air, and the total luminous flux can be increased.

  In the light emitting device 1 according to the present embodiment described above, the LED chip 10 and the metal plate 21 are submount members that relieve stress acting on the LED chip 10 due to a difference in linear expansion coefficient between the LED chip 10 and the metal plate 21. Since the submount member 30 which is larger than the chip size of the chip 10 and thermally couples the LED chip 10 and the metal plate 21 is interposed, the heat dissipation is high and the LED is caused by the difference in the linear expansion coefficient. The chip 10 can be prevented from being damaged, and the reliability can be improved.

  In the light emitting device 1 of the present embodiment, the sealing portion 50 that seals the LED chip 10 and the bonding wires 14 and 14 on the mounting surface side of the LED chip 10 on the mounting substrate 20 is formed of silicone resin. Therefore, compared with the case where it is formed with an epoxy resin, weather resistance can be improved, and deterioration due to light emitted from the LED chip 10 does not easily occur, and reliability is further enhanced.

  Further, in the light emitting device 1 of the present embodiment, the sealing unit 50 contains a phosphor that is excited by light emitted from the LED chip 10 and emits light of a color different from the emission color of the LED chip 10. Since it is formed in the shape of a convex lens, the directivity of the mixed color light of the light emitted from the LED chip 10 and the light emitted from the phosphor can be enhanced.

  By the way, in the above-described embodiment, a blue LED chip whose emission color is blue is adopted as the LED chip 10, and a SiC substrate is adopted as the conductive substrate 11, but a GaN substrate is used instead of the SiC substrate. In the case of using a SiC substrate or a GaN substrate, the crystal growth substrate has a higher thermal conductivity than the case of using a sapphire substrate as an insulator as the crystal growth substrate. Thermal resistance can be reduced. Further, the light emission color of the LED chip 10 is not limited to blue, and may be, for example, red or green. That is, the material of the light-emitting portion 12 of the LED chip 10 is not limited to the GaN-based compound semiconductor material, and a GaAs-based compound semiconductor material, a GaP-based compound semiconductor material, or the like may be employed according to the emission color of the LED chip 10. Further, the conductive substrate 11 is not limited to the SiC substrate, and may be appropriately selected from, for example, a GaAs substrate and a GsP substrate according to the material of the light emitting unit 12.

It is a schematic sectional drawing which shows embodiment. It is a general | schematic disassembled perspective view which showed the same and partially fractured | ruptured. It is a principal part schematic plan view which shows the same as the above. The insulating base material same as the above is shown, (a) is a schematic plan view, (b) is a schematic cross-sectional view. The lighting fixture using the same is shown, (a) is a principal part schematic plan view, (b) is a principal part schematic sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 LED chip 14 Bonding wire 20 Mounting board 21 Metal plate 22 Insulating base material 23 Lead pattern 24 Window hole 30 Submount member 40 Reflector 50 Sealing part 50a Light emission surface

Claims (1)

  An LED chip, a mounting substrate on which the LED chip is mounted, and a reflector that surrounds the LED chip on the mounting surface side of the LED chip on the mounting substrate and reflects light emitted from the LED chip, and opens as the distance from the mounting surface increases A reflector formed in a shape whose area gradually increases, and a sealing portion that seals the LED chip and a pair of bonding wires electrically connected to the LED chip, the mounting substrate includes a metal plate, A pair of lead patterns that are electrically connected to both electrodes of the LED chip are provided on the surface opposite to the metal plate side, and a window hole is provided in a portion corresponding to the LED chip and is laminated on the metal plate The LED chip has one electrode on one surface side and the other electrode on the other surface side. A submount member that relieves stress acting on the LED chip due to a difference in linear expansion coefficient between the LED chip and the metal plate, and is larger than the chip size of the LED chip. The submount member is mounted on a metal plate via a submount member that is thermally coupled to the submount member, and the submount member side electrode is connected to one bonding wire via a conductor pattern provided on the submount member and the submount. The electrode on the side opposite to the member side is directly connected to the other bonding wire, and the sealing portion is formed of a silicone resin and is excited by light emitted from the LED chip and has a color different from that of the LED chip. A light-emitting device comprising a phosphor that emits light and having a convex lens shape.

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