JP2005136137A - Semiconductor light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve, with a simplified structure, heat radiation property, prevent deterioration by aging due to heat, prevent the peeling of the semiconductor light emitting element due to the heat, and prevent breakdown by static electricity. <P>SOLUTION: The semiconductor light emitting device comprises a base 18 on which an LED chip 11 is mounted; a case 16 including a reflector surface 17 which is formed through surface process such as silver plating or the like, a first electrode 12; a second electrode 13; a first lead 14; a second lead 15; and a heat-proof transparent glass cover 20. The case 16 including the base 18 has the thermal expansion coefficient equal to that of the LED chip 11 and is manufactured with a silicon carbide system composite material of silicon carbide/silicon/ aluminum having the thermal expansion coefficient which is higher than that of an inorganic material such as an ordinary ceramics. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a semiconductor light emitting device disposed in a case in which a semiconductor light emitting element is mounted on a base and a reflector surface is formed.

In recent years, the output of LEDs has been remarkably increased, and incandescent bulbs with a light source efficiency of 151 m / W and halogen lamps with a light source efficiency of 201 m / W are being developed. However, in order to realize a semiconductor light emitting device used for various home appliances, OA equipment, in-vehicle equipment, etc. indicator lights, indoor indicator lights, traffic light indicator lights, automobile side back or front lights, etc. A problem exists. One of the problems is that a large current must be passed through the LED in order to increase the amount of light emitted, but if a large current is passed through, the heat generated by the LED will increase and the luminous efficiency will decrease. As the LED temperature rises, the luminous efficiency decreases due to phenomena such as phonon scattering. Further, in a semiconductor light emitting device provided with a resin reflector, when the temperature rises significantly, the resin reflector deteriorates with age and the reflection efficiency decreases. Further, in a semiconductor light emitting device having a base portion made of a metal material, a fatal problem that the mounted LED chip peels off from the base portion also occurs. Because of these various factors, a high light emission type semiconductor light emitting device cannot be realized immediately even if a large current is passed.

Japanese Patent Application Laid-Open No. 2003-152225 (Patent Document 1) includes a metal plate made of a metal material having high thermal conductivity such as aluminum and having a projecting portion projecting forward and having a housing recess that opens to the front surface. A light emitting diode chip mounted on the bottom surface of the housing recess and thermally coupled to the metal plate, and an insertion hole into which the protrusion is inserted is formed and joined to the back surface of the metal plate. An insulating substrate, a resin frame member joined to the surface of the insulating substrate and surrounding the light emitting diode chip and the protruding portion, and a resin portion having translucency and sealing the light emitting diode chip. A light emitting device is disclosed. In this conventional light emitting device, since the base part on which the light emitting diode chip is mounted is formed of a metal member, heat dissipation is improved, but the resin frame member is deteriorated due to heat over time. There is. Further, since the insulating substrate is sandwiched between the resin frame member and the metal member, there is a problem that the structure is complicated and the manufacturing cost is increased.

  Japanese Patent Laying-Open No. 2003-243718 (Patent Document 2) discloses a ceramic substrate having a housing recess opened on the front surface, a light emitting diode chip mounted on the bottom surface of the housing recess, and the ceramic substrate. The light-emitting device comprised from the thermal radiation means arrange | positioned at the back surface of this is disclosed. General ceramic materials such as alumina ceramics, zirconia ceramics, and silicon nitride ceramics have a thermal conductivity of about 80 W / m · K at the highest, and have low heat dissipation. In addition, AlN ceramics listed as high thermal conductive ceramics have a thermal conductivity of about 160 to 170 W / m · K, and the thermal conductivity is not yet satisfactory. Moreover, these ceramic materials also have a problem of high processing costs. And the said thermal radiation means is comprised by the ceramic thermal radiation fin or the metal member. Since this conventional light emitting device is provided with a heat radiating means, improvement in heat dissipation is achieved. Moreover, since the resin member is not included, suppression of aging deterioration due to heat is also achieved. However, since the housing recess opened on the front surface includes parts such as a ceramic substrate and a ceramic heat radiation fin formed on the surface, processing is not easy, and thus there is a problem that the manufacturing cost increases. Furthermore, since general ceramics have no electrical conductivity, there is a problem that a countermeasure against charging must be taken on the light emitting device itself.

Further, Patent Document 2 discloses a metal substrate such as aluminum having a housing recess formed on the front surface and a ceramic layer formed on the surface by coating, and a light emitting diode mounted on the bottom surface of the housing recess. A light emitting device including a chip is also disclosed. Since this conventional light emitting device includes an aluminum substrate, the heat dissipation is improved. Moreover, since the resin member is not included, suppression of aging deterioration due to heat is also achieved. However, it is not easy to process with a metal substrate having a ceramic layer formed on the surface, and therefore there is a problem that the manufacturing cost increases. Further, since the thermal expansion coefficients of the aluminum substrate and the light-emitting diode chip are greatly different, there is a possibility that the light-emitting diode chip is peeled off from the aluminum substrate if the light-emitting diode chip generates significant heat.

Furthermore, in the monthly material stage (Non-patent Document 1) issued on June 10, 2003, the main body is a metal package, and a semiconductor light emitting device provided with a metal heat sink on which an LED chip is placed and an electrode for supplying current are provided. An apparatus is disclosed. The metal heat sink is formed with a substantially funnel-shaped storage recess reflector at the center, and a pair of electrodes are provided through the periphery. The metal package is a substantially cylindrical metal member, and one end is sealed with a transparent glass lid. A metal heat sink in which an LED chip is mounted at the center and a pair of electrodes penetrates and is attached to the peripheral portion is covered with the metal package in an airtight manner. The semiconductor light emitting device configured in this way has a hollow structure.

Since this semiconductor light emitting device does not use resin, there is no problem that the amount of light decreases due to yellowing (deterioration) of the resin due to heat generation and accumulation of the LED chip. In addition, the heat generated by the LED chip is radiated through a metal heat sink that is directly connected to the external substrate, so the heat dissipation is high. However, in order to realize sufficient heat dissipation, there is a problem that the metal heat sink must be enlarged. Further, since the semiconductor light emitting device has a hollow structure, there is a problem that the structure of the metal heat sink and the metal package becomes complicated.

  As described above, in the conventional semiconductor light emitting device, even if a high-power LED is adopted, various adverse effects due to the amount of emitted light cannot be prevented, and there is a limit to increasing the amount of emitted light. For this reason, the use of the semiconductor light emitting device cannot be expanded to a high light emission amount indicator lamp or a lamp region.

JP 2003-152225 A JP 2003-243718 A Kanto Kanto “Challenges for High LED Output and Lighting Market” Monthly Material Stage Published June 10, 2003

  The problem to be solved by the present invention is a semiconductor light emitting device configured by mounting a semiconductor light emitting element on a base portion of a case having a housing recess in which a reflector surface is formed. It is to realize deterioration prevention, prevention of peeling of the semiconductor light emitting element by heat, and prevention of electrostatic breakdown with a simple structure.

  In order to solve the above-described problem, in a semiconductor light-emitting device in which a semiconductor light-emitting element is mounted on a base portion of a case having a housing recess in which a reflector surface is formed, at least the base portion emits the semiconductor light-emitting device. It is composed of an inorganic metal composite material that has a thermal expansion coefficient equivalent to the thermal expansion coefficient of the element and higher thermal conductivity (about 200 W / m · K or more) than that of general inorganic materials such as ceramics. .

According to the present invention, improvement in heat dissipation, prevention of aging deterioration due to heat, prevention of peeling of a semiconductor light emitting element due to heat, and prevention of electrostatic breakdown can be realized with a simple structure. Accordingly, it has become possible to provide a high-luminance semiconductor light emitting device at a low price by using a high-power LED chip using a nitride compound semiconductor such as GaN, AlGaN, or InGaN.

  The semiconductor light-emitting device according to the present invention is a semiconductor light-emitting device in which a semiconductor light-emitting element is mounted on a base portion of a case having a housing recess in which a reflector surface is formed, wherein the case is a heat of the semiconductor light-emitting element. The case is characterized by being integrally formed of a composite material of an inorganic metal having a thermal expansion coefficient equivalent to the expansion coefficient and having a thermal conductivity higher than that of an inorganic material such as ceramics.

Embodiment 1 of the present invention includes a base portion 18 on which an LED chip 11 is mounted, a case 16 on which a reflector surface 17 is formed, as shown in a sectional view (A) and a plan view (B) in FIG. The semiconductor light emitting device includes the first lead 14, the second lead 15, and the heat-resistant transparent glass lid 20.

  The case 16 having a substantially rectangular outer shape has a substantially funnel-shaped storage recess whose hole diameter gradually increases upward from the bottom surface. The surface of the substantially funnel-shaped storage recess is subjected to a surface treatment such as silver plating to form a reflector portion 17 that reflects light emitted from the LED chip 11 toward a wide opening of the substantially funnel-shaped storage recess. The bottom surface of the substantially funnel-shaped storage recess of the case 16 is above the base portion 18. The base portion 18 of the case 16 and the portion where the substantially funnel-shaped storage recess is formed are integrally formed of the same inorganic metal composite material.

  On the upper surface of the base part 18, the first electrode part 12 and the second electrode part 13 of a conductive thin film are arranged and bonded with an insulating adhesive. An end portion 14 a of the first lead 14 is connected to the first electrode portion 12, and an end portion 15 a of the second lead 15 is connected to the second electrode portion 13. The first lead 14 and the second lead 15 which are thin copper plates are bonded to the case 16 with an insulating adhesive such as low melting point glass. The LED chip 11 is mounted on the first electrode portion 12 and bonded by a conductive adhesive such as silver paste. Thereby, the lower surface electrode of the LED chip 11 is electrically connected to the first lead 14 via the first electrode portion. On the other hand, the upper surface electrode of the LED chip 11 is electrically connected to the second electrode portion 13 via a gold wire 19 which is a bonding wire.

  The base portion 18 is made of a silicon carbide composite material having a thermal expansion coefficient of about 4.7 ppm / ° C. and a thermal conductivity of 200 to 240 W / m · K. In short, the thermal expansion coefficient of the base part 18 is substantially equal to the thermal expansion coefficient of about 5.5 ppm / ° C. of the LED chip 11 using the nitride compound semiconductor of GaN, and the thermal conductivity of the base part 18 is a general ceramic. Higher than inorganic materials. Therefore, in the semiconductor light emitting device of Example 1, the base portion 18 on which the LED chip 11 is mounted functions as a heat sink that effectively releases the heat generated by the LED chip 11 to the outside of the case. Further, since the thermal conductivities are substantially equal, the LED chip 11 does not peel from the base portion 18 even when the LED chip 11 becomes extremely hot.

The silicon carbide-based composite material is, for example, a silicon carbide / silicon / aluminum composite material having a SiC content of 70%, an Al / Si content of 30%, and an Al / Si ratio of 40:60.

A first manufacturing method of the case 16 including the base portion 18 is as follows. That is, the case 16 in which the substantially funnel-shaped storage concave portion in which the reflector portion 17 is formed and the base portion 18 on which the LED chip 11 is mounted is integrally formed of an inorganic metal composite material is the above-described silicon carbide composite. It is manufactured by cutting a block of material into a predetermined shape and applying a final polishing process.

A second manufacturing method of the case 16 including the base portion 18 is as follows. That is, the case 16 in which the substantially funnel-shaped storage recess in which the reflector portion 17 is formed and the base portion 18 on which the LED chip 11 is mounted is integrally formed of an inorganic metal composite material is an SiC powder injection molding process. It is manufactured through a degreasing process and an AlSi alloy melt infiltration process. The SiC powder injection molding step is a step of adding a thermoplastic resin such as wax, PVA, PVB, polystyrene or the like to the SiC powder and injection molding it into a predetermined shape to obtain a SiC molded body. The degreasing step is a step of removing the additive by heating the SiC molded body at 300 to 1000 ° C. in an inert atmosphere such as Ar or N ₂ . The AlSi alloy melt infiltration step is a step in which the AlSi alloy is melt infiltrated into the SiC molded body that has undergone the degreasing step at a temperature of 700 to 1800 ° C. in an inert atmosphere such as Ar or N ₂ .

According to the second manufacturing method of the case 16, the silicon carbide composite having a thermal expansion coefficient equivalent to the thermal expansion coefficient of the semiconductor light-emitting element and higher thermal conductivity than inorganic materials such as ceramics, along with the molding of the case There is an advantage that a material can be obtained.

As described above, the present invention provides a semiconductor light-emitting device in which a semiconductor light-emitting element is mounted on a base portion of a case having a housing recess in which a reflector surface is formed. At least the base portion of the semiconductor light-emitting element is disposed on the base portion. It is characterized in that it is composed of a composite material of an inorganic metal having a thermal expansion coefficient equivalent to the thermal expansion coefficient and having a higher thermal conductivity than that of a general inorganic material such as ceramics. The inorganic metal composite material is easier to process than inorganic materials such as general ceramics that can only be polished. Therefore, the semiconductor light emitting device of Example 1 has a feature that the structure is simple and easy to process. Further, since the base portion is made of an inorganic metal, it is not necessary to take special measures against electrostatic breakdown.

  Since the present invention is a semiconductor light emitting device of a high light emission amount type, it is widely used for indicator lights of various home appliances, OA equipment, in-vehicle equipment, indoor indicator lights, signal indicator lights, automobile side back or front lights, etc. It is what is done.

It is sectional drawing (A) and top view (B) of the semiconductor light-emitting device of Example 1 of this invention.

Explanation of symbols

11 LED chip 12, 13 Thin film electrode portion 14 First lead 14a First lead end portion 14b First lead electrode portion 15 Second lead 15a Second lead end portion 15b Second lead electrode Part 16 Case 17 Reflector surface 18 Base 19 Gold wire 20 Heat-resistant transparent glass lid

Claims (6)

In a semiconductor light emitting device configured by mounting a semiconductor light emitting element on a base portion of a case having a housing recess in which a reflector surface is formed, the base portion has a thermal expansion equivalent to a thermal expansion coefficient of the semiconductor light emitting element. A semiconductor light emitting device comprising a composite material of an inorganic metal having a higher thermal conductivity than an inorganic material such as ceramics. In a semiconductor light-emitting device configured by mounting a semiconductor light-emitting element on a base portion of a case having a housing recess in which a reflector surface is formed, the case has a thermal expansion coefficient equivalent to that of the semiconductor light-emitting element. A semiconductor light emitting device comprising a case made of an inorganic metal composite material having a thermal conductivity higher than that of an inorganic material such as ceramics. 2. The semiconductor light-emitting device according to claim 1, wherein the inorganic metal composite material is a silicon carbide / silicon / aluminum composite material. The case is subjected to a degreasing step of heating a SiC molded body obtained by adding wax, PVA, PVB, polystyrene, etc. to SiC powder at 300 to 1000 ° C. in an inert atmosphere such as Ar or N ₂ . It is manufactured by melting and infiltrating an AlSi alloy into a SiC molded body that has undergone the degreasing step at a temperature of 700 to 1800 ° C in an inert atmosphere such as Ar or N _2. Semiconductor light emitting device. 3. The semiconductor light emitting device according to claim 2, wherein the case is manufactured by cutting a silicon carbide / silicon / aluminum composite material into a predetermined shape. The semiconductor light emitting device according to claim 1, wherein the opening of the case is sealed with a heat resistant transparent glass lid.

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