JP4484499B2 - Light emitting device - Google Patents

Description

The present invention relates to a light emitting device that converts the wavelength of light emitted from a light emitting element with a phosphor and emits light to the outside.

  A light emitting device that emits white light by converting long wavelengths of light such as near-ultraviolet light and blue light emitted from a light emitting element 15 such as a conventional light emitting diode (LED) with a plurality of phosphors such as red, green, blue, and yellow. Is shown in FIG. In FIG. 3, the light-emitting device has a mounting portion 11a for mounting the light-emitting element 15 at the center of the upper main surface, and electrically connects the inside and outside of the light-emitting device from the mounting portion 11a and its periphery. A base 11 made of an insulator on which a wiring conductor (not shown) made of lead terminals, metallized wiring, etc. is formed, and a through hole 12a that is bonded and fixed to the upper surface of the base 11 and whose upper opening is larger than the lower opening. In addition, a frame-like reflecting member 12 whose inner peripheral surface is a reflecting surface 12b that reflects light emitted from the light emitting element 15, and excitation of light emitted from the light emitting element 15 filled inside the reflecting member 12 It is mainly composed of a transparent resin 13 containing a phosphor for long wavelength conversion and a light emitting element 15 mounted and fixed on the mounting portion 11a.

  The substrate 11 is made of an aluminum oxide sintered body (alumina ceramic), an aluminum nitride sintered body, a mullite sintered body, ceramics such as glass ceramics, or a resin such as epoxy resin. When the substrate 11 is made of ceramic, the wiring conductor is formed on its upper surface by firing a metal paste made of tungsten (W), molybdenum (Mo) -manganese (Mn), etc. at a high temperature. When the base 11 is made of a resin, lead terminals made of copper (Cu), iron (Fe) -nickel (Ni) alloy, etc. are molded and fixed inside the base 11.

  The reflecting member 12 has a frame shape in which a through hole 12a having an upper opening larger than the lower opening is formed and a reflecting surface 12b for reflecting light is provided on the inner peripheral surface. Specifically, it consists of metals such as aluminum (Al) and Fe-Ni-cobalt (Co) alloys, ceramics such as alumina ceramics or resins such as epoxy resins, and molding technologies such as cutting, die molding or extrusion molding. It is formed by.

  Further, the reflecting surface 12b of the reflecting member 12 is coated by polishing or flattening the inner peripheral surface of the through hole 12a or by depositing a metal such as Al on the inner peripheral surface of the through hole 12a by vapor deposition or plating. It is formed by wearing. The reflecting member 12 is bonded to the upper surface of the base 11 by a soldering material such as solder, silver (Ag) solder, or a bonding material such as a resin adhesive so as to surround the mounting portion 11a with the inner peripheral surface of the reflecting member 12. Is done.

Then, the wiring conductor arranged around the mounting portion 11a and the light emitting element 15 are electrically connected through the electrical connection means 16 such as a bonding wire or a metal ball, and then an epoxy resin containing a phosphor or Transparent light 13 such as silicone resin is filled in the reflective member 12 so as to cover the light emitting element 15 with an injection machine such as a dispenser, and is thermally cured in an oven, so that the light from the light emitting element 15 is converted into a long wavelength by a phosphor. Thus, a light emitting device capable of extracting light having a desired wavelength spectrum can be obtained.
Japanese Patent Laid-Open No. 2003-37298

  In recent years, it has been desired to further increase the radiation intensity of the light emitting device. However, in the above conventional light emitting device, if the current value input to the light emitting element 15 is increased to increase the radiation intensity, the light emission intensity of the light emitting element 15 tends to vary near the limit, and a stable radiation intensity can be obtained. It had the problem that it was not possible.

  Further, the light emitted downward from the light emitting element 15 is not irradiated well on the reflecting member 12, and is irradiated on the upper surface of the base 11 having a relatively low light reflectivity and the junction between the base 11 and the reflecting member 12, All of the light emitted from the light-emitting element 15 is absorbed by these parts and cannot be reflected with high reflectivity, and the radiation intensity, axial luminous intensity, luminance, and color rendering properties from the light-emitting device are likely to decrease. Had problems.

  Furthermore, although the heat generated from the light emitting element 15 is transmitted to the outside through the base 11, the amount of heat generated from the light emitting element 15 has recently increased due to the increase in the output of the light emitting element 15. It has been difficult to completely dissipate the heat generated from 15 through the substrate 11 to the outside. As a result, the temperature of the light emitting element 15 is increased, the output of the light emitting element 15 is decreased, and a stable radiation intensity cannot be obtained.

  Accordingly, the present invention has been completed in view of the above-described conventional problems, and its purpose is to increase the light emission intensity of light emitted from the light-emitting element and to achieve optical characteristics such as on-axis luminous intensity, luminance, and color rendering. It is to improve.

The light-emitting device of the present invention includes a base having a mounting portion for a light-emitting element protruding from the upper main surface, a light-emitting element mounted on the mounting portion, and the mounting portion on the upper main surface of the base. A frame-shaped reflecting member that is joined so as to surround and has an inner peripheral surface that is a reflecting surface that reflects light emitted from the light emitting element, and is provided inside the reflecting member so as to cover the light emitting element. The light emitting element has a light emitting portion located above the lower end of the reflecting surface, and the light transmitting member is located above the upper surface of the mounting portion. positioned above, it consists of two layers of a lower layer portion positioned below the upper surface of the upper portion and the mounting section you covering an upper surface of the light emitting element, wherein the lower portion contains the metal particles And the upper layer portion contains a phosphor that converts the wavelength of light emitted from the light emitting element. That.

  In the light emitting device of the present invention, the light emitting element emits light on the inner peripheral surface joined to the base having the mounting portion of the light emitting element protruding from the upper main surface and the upper main surface of the base so as to surround the mounting portion. A frame-like reflecting member that is a reflecting surface for reflecting light, and a translucent member provided so as to cover the light emitting element inside the reflecting member. Is located above the lower end of the reflecting surface, and the translucent member includes an upper layer portion located above the upper surface of the placement portion and a lower layer portion located below the upper surface of the placement portion. It consists of two layers, and the lower layer contains metal particles and the upper layer contains a phosphor that converts the wavelength of light emitted by the light emitting element, so that the light emitted downward from the light emitting element is reflected by the reflecting member. Reflects on the surface of metal particles and reflects all light emitted from the light emitting element with high reflectivity It can be.

  Moreover, by irregularly reflecting the light from the light emitting element with the metal particles in the lower layer part of the translucent member, the phosphors in the upper layer part can be uniformly irradiated with light, and the wavelength conversion is performed with more phosphors. As a result, the wavelength conversion efficiency becomes extremely high, and the radiation intensity, axial luminous intensity, luminance, and color rendering can be further increased.

  Furthermore, by not containing metal particles in the upper layer portion of the translucent member, it is possible to effectively prevent light from being irregularly reflected near the surface of the translucent member and to emit light at a desired radiation angle. The radiation intensity from the light emitting device can be made extremely high and the directivity can be made high.

  Further, even when heat generated from the light emitting element is transmitted to the base, the heat can be transferred from the protruding mounting portion to the reflecting member through the metal particles, and not only from the base but also in the translucent member. Even through the metal particles and the reflecting member, the heat generated from the light emitting element can be efficiently dissipated to the outside. As a result, even if the amount of heat generated from the light-emitting element increases, the heat generated from the light-emitting element can be completely dissipated to the outside, and as a result, the temperature of the light-emitting element is prevented from rising and stable radiation intensity is obtained. Be able to.

  Furthermore, even if stress due to a difference in thermal expansion occurs between the reflecting member and the substrate due to heat when the light emitting device is mounted on the external electric circuit board or heat of the light emitting element, it is moderately hard due to including metal particles. The lower layer part of the translucent member that is easily deformable is deformed according to the thermal expansion of the reflective member or the base, or restrains the reflective member or the base to effectively stress the thermal expansion of the reflective member or the base. Can be absorbed into. As a result, it is possible to effectively suppress the occurrence of cracks and the like in the base body and the reflecting member.

  As a result, the light characteristics such as on-axis luminous intensity, luminance, and color rendering can be improved.

  The light emitting device of the present invention will be described in detail below. FIG. 1 is a cross-sectional view showing an example of an embodiment of a light emitting device of the present invention. In this figure, 1 is a substrate, 2 is a reflecting member, 3 is a translucent member, and 4 is a metal particle, and these mainly constitute a light emitting device that can emit light emitted from the light emitting element 5 to the outside with directionality. .

  The light emitting device according to the present invention includes a base 1 having a mounting portion 1a for the light emitting element 5 protruding from the upper main surface, and an inner circumference joined to the upper main surface of the base 1 so as to surround the mounting portion 1a. A frame-shaped reflecting member 2 whose surface is a reflecting surface 2 b that reflects light emitted from the light emitting element 5, and a translucent member 3 provided inside the reflecting member 2 so as to cover the light emitting element 5. The light emitting element 5 has a light emitting portion located above the lower end of the reflecting surface 2b, and the translucent member 3 is an upper layer portion 3a located above the upper surface of the mounting portion 1a. And the lower layer portion 3b positioned below the upper surface of the mounting portion 1a. The lower layer portion 3b contains the metal particles 4, and the upper layer portion 3a emits light emitted from the light emitting element 5. Contains the phosphor to be converted.

  The substrate 1 in the present invention is made of alumina ceramic, aluminum nitride sintered body, mullite sintered body, ceramic such as glass ceramic, or resin such as epoxy resin. Moreover, the base body 1 has a mounting portion 1a that protrudes from the upper main surface, on which the light emitting element 5 is mounted, on the upper main surface.

  Such a mounting portion 1a is formed on the upper main surface of the substrate 1 with ceramics such as alumina ceramics, aluminum nitride sintered body, mullite sintered body, glass ceramics, Fe-Ni-Co alloy, Cu-W, or the like. The protrusion 1b made of a metal or epoxy resin is attached to the upper surface of the substrate 1 with a bonding material such as a brazing material or an adhesive, or the protrusion 1b is mounted on the upper surface of the substrate 1. And may be formed as one piece. Further, the protrusion 1b made of the above-mentioned ceramic, metal or resin is provided in the through-hole provided in the central portion of the base 1 by fitting it so that its upper side protrudes from the upper surface of the base 1. Also good.

  Preferably, the protrusion 1b and the base 1 are made of the same material. Thereby, the difference in thermal expansion between the mounting portion 1a and the base 1 can be reduced, and it is possible to effectively suppress the occurrence of distortion in the mounting portion 1a, the displacement of the light emitting element 5 and the reduction in light emission efficiency. .

  Further, when the convex portion 1b is integrated with the base body 1, for example, by laminating ceramic green sheets to be the convex portion 1b and the base body 1 and firing them simultaneously, by a metal processing method such as cutting, or It can be produced by molding a resin by injection molding or the like.

  On the mounting portion 1a, an electrical connection pattern (not shown) for electrically connecting the light emitting element 5 is formed. The electrical connection pattern is led out to the outer surface of the light emitting device through a wiring layer (not shown) formed inside the base 1 and connected to the external electrical circuit board, whereby the light emitting element 5 and the external electrical circuit are connected. Are electrically connected to each other.

  As a method of connecting the light emitting element 5 to the electrical connection pattern, a method of connecting through wire bonding or a flip chip bonding method in which the lower surface of the light emitting element 5 is connected by electrical connection means 6 such as a solder bump is used. A method or the like is used. Preferably, the connection is made by a flip chip bonding method. Thereby, since the electrical connection pattern can be provided immediately below the light emitting element 5, it is not necessary to provide a space for providing the electrical connection pattern on the upper surface of the base 1 around the light emitting element 5. Therefore, it is possible to effectively suppress the light emitted from the light emitting element 5 from being absorbed in the space for the electrical connection pattern of the substrate 1 and the on-axis luminous intensity being lowered.

  The electrical connection pattern is formed, for example, by forming a metallized layer of a metal powder such as W, Mo, Cu, or Ag on the surface or inside of the base 1 so that lead terminals such as Fe-Ni-Co alloy are formed on the base 1. It is provided by embedding or by fitting and joining an input / output terminal made of an insulator on which a wiring conductor is formed in a through hole provided in the base 1.

  The exposed surface of the electrical connection pattern should be coated with a metal having excellent corrosion resistance, such as Ni or gold (Au), with a thickness of about 1 to 20 μm. Can be effectively prevented, and the connection between the light emitting element 5 and the electrical connection pattern can be strengthened. Therefore, for example, a Ni plating layer having a thickness of about 1 to 10 μm and an Au plating layer having a thickness of about 0.1 to 3 μm are sequentially deposited on the exposed surface of the electrical connection pattern by an electrolytic plating method or an electroless plating method. More preferably.

  Further, the reflecting member 2 is attached to the upper surface of the substrate 1 by a bonding material such as solder, a brazing material such as Ag brazing, or an adhesive such as an epoxy resin. The reflection member 2 has a through hole 2a formed at the center and an inner peripheral surface that is a reflection surface 2b that reflects light emitted from the light emitting element 5.

  The reflecting member 2 is formed by performing cutting or molding on the reflecting member 2. Alternatively, a highly reflective metal thin film such as Al, Ag, Au, platinum (Pt), titanium (Ti), chromium (Cr), or Cu is formed on the inner peripheral surface of the through hole 2a by, for example, plating or vapor deposition. By doing so, the reflective surface 2b may be formed. When the reflecting surface 2b is made of a metal that is easily discolored by oxidation such as Ag or Cu, an Ni plating layer having a thickness of about 1 to 10 μm and an Au plating layer having a thickness of about 0.1 to 3 μm are formed on the surface. Is preferably deposited sequentially by electrolytic plating or electroless plating. Thereby, the corrosion resistance of the reflective surface 2b improves.

  Further, the arithmetic average roughness Ra on the surface of the reflecting surface 2b is preferably 0.004 to 4 μm, whereby the reflecting surface 2b can favorably reflect the light of the light emitting element 5 and the phosphor. When Ra exceeds 4 μm, the light of the light emitting element 5 cannot be reflected uniformly, and is irregularly reflected inside the light emitting device. On the other hand, if it is less than 0.004 μm, it tends to be difficult to form such a surface stably and efficiently.

  The reflecting surface 2b has, for example, a linear inclined surface as shown in FIGS. 1 and 2 whose longitudinal cross-sectional shape spreads outward as it goes upward, and a curved slope that spreads outward as it goes upward Examples of the shape include a surface and a rectangular surface.

  The reflecting member 2 may be attached to any part other than the convex portion 1b on the upper surface of the substrate 1, but the light emitting element 5 is disposed around the light emitting element 5 with a desired surface accuracy, for example, in the longitudinal section of the light emitting device. It is preferable that the reflective surface 2b is provided so as to be provided in a state where the reflective surfaces 2b provided on both sides of the light emitting element 5 are symmetrically sandwiched therebetween. Thereby, not only the light from the light emitting element 5 is wavelength-converted by the phosphor and directly radiated to the outside, but also the light emitted from the light emitting element 5 in the lateral direction or the light emitted downward from the phosphor. The reflecting surface 2b can be uniformly reflected, and the axial luminous intensity, luminance, color rendering properties, and the like can be effectively improved.

  In particular, as shown in FIG. 2, the above-described effect appears more prominently as the reflecting member 2 is closer to the convex portion 1 b. Thereby, by enclosing the circumference | surroundings of the convex part 1b which has the mounting part 1a with the reflection member 2, more light can be reflected and it becomes possible to obtain a higher on-axis luminous intensity.

  Moreover, the light emission part of the light emitting element 5 mounted on the mounting part 1a is provided so that it may become a position higher than the lower end 2c of the reflective surface 2b. That is, the height of the light emitting portion of the light emitting element 5 from the upper main surface of the base 1 is larger than the thickness L of the reflecting member 2 around the lower opening of the through hole 2a. Thereby, the light emitted from the light emitting element 5 is diffusely reflected by burrs generated at the lower end 2c of the reflecting surface 2b during the processing of the reflecting member 2 or by the brazing material protruding when the reflecting member 2 is joined to the base 1. In addition to being able to effectively prevent absorption, it is possible to irradiate a large amount of phosphor near the surface of the translucent member 3 with light emitted from the light emitting element 5, and to achieve very good wavelength conversion efficiency. obtain.

  The translucent member 3 of the present invention is made of a transparent resin such as an epoxy resin or a silicone resin. The translucent member 3 is filled in the reflecting member 2 so as to cover the light emitting element 5 with an injection machine such as a dispenser, and is thermally cured in an oven or the like, so that the light from the light emitting element 5 is converted into a wavelength by a phosphor. It is possible to extract light having a desired wavelength spectrum after conversion.

  Here, the translucent member 3 is composed of two layers of an upper layer portion 3a located above the upper surface of the placement portion 1a and a lower layer portion 3b located below the upper surface of the placement portion 1a. Since the part 3b contains the metal particles 4 and the upper layer part 3a contains a phosphor that converts the wavelength of light emitted from the light emitting element 5, the light emitted downward from the light emitting element is reflected by the reflecting member 2 and It is possible to reflect all of the light emitted from the light emitting element 5 with a high reflectance by reflecting on the surface of the metal particles 4.

  Moreover, by irregularly reflecting the light from the light emitting element 5 with the metal particles 4 in the lower layer portion 3b of the translucent member 3, it is possible to uniformly irradiate the phosphor of the upper layer portion 3a with more fluorescence. By converting the wavelength with the body, the wavelength conversion efficiency becomes extremely high, and the radiation intensity, the on-axis luminous intensity, the luminance, and the color rendering can be further increased.

  Further, by not containing the metal particles 4 in the upper layer portion 3a of the translucent member 3, it is possible to effectively prevent light from being diffusely reflected near the surface of the translucent member 3, and to emit light at a desired radiation angle. The intensity of radiation from the light emitting device can be made extremely high and the directivity can be made high.

  Further, even if the heat generated from the light emitting element 5 is transmitted to the base body 1, the heat can be satisfactorily transmitted from the protruding mounting portion 1 a to the reflecting member 2 through the metal particles 4, and not only from the base body 1. The heat generated from the light emitting element 5 can be efficiently dissipated to the outside even through the metal particles 4 and the reflecting member 2 in the translucent member 3. As a result, even if the amount of heat generated from the light emitting element 5 increases, the heat generated from the light emitting element 5 can be completely dissipated to the outside. As a result, the temperature of the light emitting element 5 is prevented from rising and stable radiation is achieved. Strength can be obtained.

  Furthermore, even if a stress due to a difference in thermal expansion occurs between the reflecting member 2 and the substrate 1 due to heat when the light emitting device is mounted on the external electric circuit board or heat of the light emitting element 5, the metal particles 4 are included. The lower layer portion 3b of the translucent member 3 that is moderately hard and easily deformed is deformed according to the thermal expansion of the reflecting member 2 and the base 1, or is reflected by restraining the reflecting member 2 and the base 1 The stress due to the thermal expansion of the member 2 and the substrate 1 can be effectively absorbed. As a result, it is possible to effectively suppress the occurrence of cracks or the like in the substrate 1 and the reflecting member 2.

  As a result, the light characteristics such as on-axis luminous intensity, luminance, and color rendering can be improved.

  The metal particles 4 are preferably made of a metal having a high thermal conductivity such as Ag or Al and a high light reflectivity, whereby the radiation intensity from the light emitting device can be made higher and more stable.

  In addition, the particle size of the metal particles 4 is preferably 1 to 5 μm, whereby the light emitted from the light emitting element 5 can be reflected on the surface of the metal particles 4 with a high reflectance, and the translucent member. The metal particles 4 can be reliably embedded without damaging the translucent member 3 in the interior of 3. When the particle size is less than 1 μm, the particle size becomes too small to make it difficult to reflect light emitted from the light emitting element 5 on the surface of the metal particle 4 with high reflectivity. When the particle size becomes larger than 5 μm, if heat is generated during the operation of the light emitting element 5, a large thermal expansion difference is generated between the translucent member 3 and the metal particles 4, and cracks or the like occur in the translucent member 3. In some cases, the light is irregularly reflected in the translucent member 3 and the radiation intensity from the light emitting device is lowered.

  The upper surface of the translucent member 3 is preferably convex upward as shown in FIGS. Thereby, the path length which the light radiated | emitted from the light emitting element 5 in the various directions permeate | transmits the translucent member 3 can be made near now, and it can suppress effectively that the nonuniformity of radiation intensity arises.

  In addition, this invention is not limited to the example of the above embodiment, If it is in the range which does not deviate from the summary of this invention, it will not interfere at all.

  For example, a plurality of light emitting elements 5 may be provided on the substrate 1 in order to improve the radiation intensity. It is also possible to arbitrarily adjust the angle of the reflecting surface 2b and the distance from the upper end of the reflecting surface 2b to the upper surface of the translucent member 3, thereby obtaining a better color rendering by providing a complementary color gamut. be able to.

It is sectional drawing which shows an example of embodiment of the light-emitting device of this invention. It is sectional drawing which shows the other example of embodiment of the light-emitting device of this invention. It is sectional drawing which shows the conventional light-emitting device.

Explanation of symbols

1: Base 1a: Placement part 2: Reflecting member 3: Translucent member 3a: Upper layer part 3b: Lower layer part 4: Metal particle 5: Light emitting element

Claims (1)

A base body having a mounting portion for the light emitting element protruding from the upper main surface;
A light emitting device placed on the placement portion, and
A frame-like reflecting member that is joined to the upper main surface of the base so as to surround the mounting portion, and whose inner peripheral surface is a reflecting surface that reflects light emitted from the light-emitting element;
A translucent member provided so as to cover the light emitting element inside the reflective member;
The light emitting element has a light emitting portion located above the lower end of the reflecting surface, and the translucent member is located above the upper surface of the mounting portion and covers the upper surface of the light emitting element. consists two layers of a lower layer portion positioned below the upper surface of the upper portion and the mounting section that overturn,
The light emitting device characterized in that the lower layer portion contains metal particles and the upper layer portion contains a phosphor that converts the wavelength of light emitted from the light emitting element.

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