JP2005209959A - Light emitting element storage package and light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting device capable of operating normally over a long period of time by efficiently reflecting the light from the light emitting element to the outside and efficiently transferring the heat from the light emitting element to the outside.
A light emitting device has a base 1 made of ceramics having a mounting portion 1a for a light emitting element 5 on an upper surface and electrode pads 1b formed on the mounting portion 1a, and a mounting on an outer peripheral portion of the upper surface of the base 1. The frame body 2 is attached so as to surround the portion 1a, and the thermoelectric cooling medium 9 is attached to the lower surface of the base body 1. The base body 1 has an average grain size of crystal grains contained in the ceramics. Is 1 to 15 μm.
[Selection] Figure 1

Description

  The present invention relates to a light emitting element housing package and a light emitting device for housing a light emitting element, and more particularly, to a light emitting element housing package and a light emitting device capable of operating the light emitting element at a constant temperature at all times.

  FIG. 5 shows a light-emitting device that houses a light-emitting element 15 such as a conventional light-emitting diode (LED) and emits light. 5 emits white light by converting light such as near-ultraviolet light and blue light emitted from the light-emitting element 15 with a plurality of phosphors 14 such as red, green, blue and yellow. Is.

  In FIG. 5, the light emitting device has a mounting portion 11a for mounting the light emitting element 15 at the center of the upper surface, and leads that electrically connect 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 a terminal, metallized wiring, or the like 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 are formed. At the same time, the frame 12 whose inner peripheral surface is a reflecting surface 12b that reflects the light emitted from the light emitting element 15, and the light emitted from the light emitting element 15 filled inside the frame 12 on the long wavelength side. It is mainly composed of a translucent member 13 containing a phosphor 14 for 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 ceramics, a wiring conductor to be the electrode pad 11b is formed on the upper surface of the substrate 11 by baking a metal paste made of tungsten (W), molybdenum (Mo) -manganese (Mn), or the like 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. In the base 11, an electrode (not shown) of the light emitting element 15 is electrically connected to an electrode pad 11b formed on the mounting portion 11a through a metal member 16 such as a gold (Au) -tin (Sn) alloy. Has been.

  Further, the frame body 12 has a frame shape in which a through hole 12a having an upper opening larger than the lower opening is formed and a reflection surface 12b for reflecting light is provided on an 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, and extrusion molding. It is produced by.

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

  Then, the electrode pad 11b made of a part of the wiring conductor disposed on the mounting portion 11a and the light emitting element 15 are electrically connected through the metal member 16 by flip chip bonding, and then the phosphor 14 is contained. By filling the inside of the frame 12 with a translucent member 13 such as an epoxy resin or a silicone resin so as to cover the light emitting element 15 with an injection machine such as a dispenser and thermally curing it in an oven, light from the light emitting element 15 is emitted. The phosphor 14 can be a light emitting device that can extract light having a desired wavelength spectrum by converting the wavelength to the longer wavelength side.

  In recent years, such a light-emitting device is desired to further increase the light extraction efficiency from the light-emitting device, and therefore, it is necessary to increase the current value input to the light-emitting element 15. However, current light emitting devices have very low efficiency of converting input power into light, and most of the input power is heat. As a result, the temperature of the light emitting element 15 is remarkably increased, and the light emission efficiency of the light emitting element 15 itself is lowered. Further, as the temperature of the light emitting element 15 rises, the deterioration of the translucent member 13 made of silicone or the like is accelerated.

In order to increase the current flowing through the light emitting element 15 while avoiding such problems, it is necessary to efficiently dissipate the heat generated in the light emitting element 15 to the outside. Therefore, the heat radiating fin 20 is joined to the lower surface of the base 11 with solder, a brazing material such as silver (Ag) brazing, or a bonding material such as a resin adhesive, so that heat generated during the operation of the light emitting element 15 is transmitted through the radiating fin 20. It has been proposed to be diffused to the outside (see, for example, Patent Document 1 below).
JP2003-338639

  However, the heat dissipating fin 20 dissipates heat into the atmosphere to dissipate the heat of the light emitting element 15, so the heat dissipating efficiency is low. The thermal conductivity of the fin 20 also tends to decrease. Therefore, when the light-emitting element 15 is operated for a long time, the temperature increase of the light-emitting element 15 cannot be suppressed by the radiating fin 20, the temperature of the light-emitting element 15 becomes very high, and the light emission efficiency is lowered. As a result, the light extraction efficiency from the light emitting device is lowered.

  Therefore, instead of the heat radiating fin 20, it may be considered to use a thermoelectric cooling medium 19 including a thermoelectric cooling element 17 that can keep the light emitting element 15 at a constant temperature as shown in FIG. 6. However, the light emitting element 15 is bonded to the thermoelectric cooling medium 19 via the base 11, and even if heat is efficiently removed by the thermoelectric cooling medium 19, the thermal conductivity of the base 11 is low. There was a problem that the heat of the element 15 could not be efficiently transferred to the thermoelectric cooling element 17.

  The base 11 also has a function of reflecting the light emitted from the light emitting element 15 and the phosphor 14 on its upper surface and radiating the light to the outside, but the light emitted from the light emitting element 15 and the phosphor 14 is emitted. When the light is reflected from the upper surface of the base 11, the light reflectivity of the upper surface of the base 11 is low, so a part of the light is absorbed by the base 11 and becomes thermal energy, and the temperature of the base 11 rises. There was also a problem that the conductivity decreased.

  In order to solve such problems, there is a method of increasing the thermal conductivity of the substrate 11 by forming a metal film having excellent thermal conductivity on the surface of the substrate 11, but the manufacturing process is increased and the manufacturing cost is extremely high. However, it has a problem of becoming higher.

  Accordingly, the present invention has been completed in view of the above-described conventional problems, and an object thereof is to efficiently reflect the light from the light emitting element to the outside and to efficiently transmit the heat from the light emitting element to the outside. Thus, a light-emitting device that can operate normally over a long period of time is provided.

  The light emitting element storage package according to the present invention includes a base body made of ceramics having a light emitting element mounting portion on the upper surface and electrode pads formed on the mounting portion, and the mounting portion described above on the outer peripheral portion of the upper surface of the base body. And a thermoelectric cooling medium attached to the lower surface of the substrate, and the substrate has an average grain size of 1 to 1 in the ceramic grains. It is characterized by being 15 μm.

  The light-emitting device of the present invention includes the light-emitting element storage package of the present invention and the light-emitting element that is mounted on the mounting portion and whose electrodes are electrically connected to the electrode pads. It is characterized by.

  In the light emitting device of the present invention, preferably, in the light emitting element, the electrode is electrically connected to the electrode pad via a metal member, and the volume of the metal member has one end surface of the electrode. The other end surface is a main surface and occupies 70% by volume or more of the volume of the columnar space defined as the main surface of the electrode pad.

  The light emitting element storage package according to the present invention surrounds the mounting portion on the upper surface of the base body made of ceramics having a mounting portion of the light emitting element on the upper surface and electrode pads formed on the mounting portion. And the thermoelectric cooling medium attached to the lower surface of the base, and the base has an average grain size of 1 to 15 μm of crystal grains contained in the ceramic. Since the crystal grains of the ceramics constituting the substrate are very dense, the grain boundaries and pores between the crystal grains are very small and the proportion of the crystal grains increases, so the thermal conductivity of the substrate is extremely high. Thus, the heat generated by the light emitting element can be efficiently dissipated to the thermoelectric cooling medium or the outside through the substrate, and the decrease in the light emitting efficiency of the light emitting element due to heat can be effectively suppressed. Therefore, it is possible to suppress a decrease in light output of the light emitting device.

  In addition, since the substrate is composed of high-density crystal grains with few grain boundaries and pores between crystal grains, the light emitted from the light-emitting element with increased reflectivity enters the substrate and is converted into thermal energy. As a result, the temperature rise of the substrate can be suppressed to improve the heat dissipation of the light emitting element, and the emitted light intensity of the light emitting device can be increased.

  In addition, since the surface of the substrate is moderately uneven due to the crystal grains occupying the surface of the substrate at a high density, the light emitted from the light emitting element is appropriately diffusely reflected so as to eliminate unevenness in light output and to emit uniformly. be able to. Furthermore, in the case where a phosphor for converting the wavelength of light emitted from the light emitting element is provided so as to cover the light emitting element, a part of the phosphor is obtained by appropriately reflecting the light emitted from the light emitting element on the surface of the substrate. In addition, more phosphors can be irradiated with light uniformly. As a result, the wavelength conversion efficiency of the phosphor can be improved, and the light output, luminance, and color rendering can be improved.

  The light-emitting device of the present invention includes the light-emitting element storage package of the present invention and a light-emitting element that is mounted on the mounting portion and the electrode is electrically connected to the electrode pad. A light-emitting device that is a feature of the light-emitting element storage package of the present invention has high radiated light intensity and can effectively dissipate heat of the light-emitting element to suppress a decrease in light emission efficiency.

  In the light emitting device of the present invention, the electrode of the light emitting element is electrically connected to the electrode pad through a metal member, and the volume of the metal member is such that one end surface is the main surface of the electrode and the other end surface is the electrode. Since it occupies 70% by volume or more of the volume of the columnar body space that is the main surface of the pad, the heat conduction from the light emitting element to the base through the metal member becomes very good, and the heat generated by the light emitting element passes through the base. Therefore, it is possible to dissipate efficiently to the thermoelectric cooling medium or the outside, so that it is possible to effectively suppress a decrease in light emission efficiency of the light emitting element due to heat. Therefore, it is possible to suppress a decrease in light output of the light emitting device.

  The light-emitting element storage package and the light-emitting device of the present invention will be described in detail using the structure shown in FIG. 1 as an example. 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, 1b is an electrode pad, 2 is a frame, 9 is a thermoelectric cooling medium, and these mainly constitute a light emitting element housing package for housing the light emitting element 5. Then, the light emitting element 5 is mounted on the mounting portion 1 a of the base 1, the electrode 5 a of the light emitting element 5 is electrically connected to the electrode pad 1 b, and the light emitting element 5 is covered with, for example, the translucent member 3. Alternatively, a light-emitting device capable of emitting light emitted from the light-emitting element 5 to the outside with directionality by sealing the light-emitting element 5 by attaching a translucent lid to the upper surface of the frame 2 is configured.

  The substrate 1 in the present invention is made of ceramics such as alumina ceramics, aluminum nitride sintered body, mullite sintered body, glass ceramics, and the like, and a wiring conductor to be an electrode pad 1b is formed on the upper surface thereof.

  The electrode pad 1b is made of a metallized layer made of a metal powder such as W, Mo, Mn, Cu, or Ag, and is formed on the surface or inside of the substrate 1. Alternatively, it may be formed by embedding a lead terminal such as an Fe—Ni—Co alloy in the substrate 1. Further, an input / output terminal made of an insulator on which the electrode pad 1b is formed may be provided by being fitted and joined to a through hole provided in the base 1.

  Further, it is preferable to deposit a metal having excellent corrosion resistance such as Ni or Au with a thickness of about 1 to 20 μm on the exposed surface of the electrode pad 1b, effectively preventing oxidative corrosion of the electrode pad 1b. In addition, the connection with the metal member 6 for electrical connection with the electrode 5a of the light emitting element 5 can be strengthened. Therefore, for example, 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 sequentially deposited on the exposed surface of the electrode pad 1b by an electrolytic plating method or an electroless plating method. More preferably.

  The substrate 1 has an average grain size of 1 to 15 μm of crystal grains contained in the ceramic. As a result, the crystal grains of the ceramic constituting the substrate 1 have a very high density, so that the grain boundaries and pores between the crystal grains become very small and the proportion of the crystal grains increases. The heat conductivity is remarkably improved, and the heat generated by the light emitting element 5 can be efficiently dissipated to the thermoelectric cooling medium 9 and the outside through the base 1, effectively reducing the light emission efficiency of the light emitting element 5 due to heat. Can be suppressed. Therefore, it is possible to suppress a decrease in light output of the light emitting device.

  Further, since the base body 1 is composed of high-density crystal grains with few grain boundaries and pores between crystal grains, the light emitted from the light-emitting element 5 with increased reflectivity enters the inside of the base body 1 and heat energy. Can be effectively suppressed, and as a result, the temperature rise of the substrate 1 can be suppressed to improve the heat dissipation of the light emitting element 5, and the emitted light intensity of the light emitting device can be increased. it can.

  In addition, since unevenness is appropriately formed on the surface of the substrate 1 by the crystal grains occupying the surface of the substrate 1 at a high density, the light emitted from the light-emitting element 5 is appropriately irregularly reflected to eliminate unevenness in light output and be uniform. Can emit radiation. Further, when the phosphor 4 for converting the wavelength of the light emitted from the light emitting element 5 is provided so as to cover the light emitting element 5, the light emitted from the light emitting element 5 is appropriately irregularly reflected on the surface of the substrate 1, Not only some of the phosphors 4 but also more phosphors 4 can be irradiated with light uniformly. As a result, the wavelength conversion efficiency of the phosphor 4 can be improved, and the light output, luminance, and color rendering can be improved.

  When the average grain size of the ceramic crystal grains of the substrate 1 is larger than 15 μm, the ratio of the crystal grains on the surface of the substrate 1 is reduced, and light entering the interior of the substrate 1 from between the crystal grains is increased. The reflectance on the upper surface is lowered, or the absorbed light is converted into thermal energy, and the temperature of the substrate 1 is likely to rise. As a result, the light emitted from the light emitting element 5 and the light emitted from the phosphor 4 are not efficiently reflected on the upper surface of the substrate 1 and the light output of the light emitting device is reduced, or the light emitting element 5 is heated to emit light. Efficiency tends to decrease. When the average grain size of the ceramic crystal grains of the substrate 1 is smaller than 1 μm, the arithmetic average roughness of the upper surface of the substrate 1 is reduced, and the light emitted from the light emitting element 5 is easily regularly reflected on the upper surface of the substrate 1. Thus, it becomes difficult to uniformly reflect in all directions, and unevenness in the intensity of the emitted light is likely to occur.

  As the substrate 1 having an average grain size of 1 to 15 μm, the ceramic raw material having an average grain size of 1 to 3 μm is used, or the heating rate during firing is 0.5 to 5 ° C./sec. It can produce by doing.

  The base body 1 has a mounting portion 1a on which the light emitting element 5 is mounted. The electrode 5a of the light emitting element 5 is electrically connected to the electrode pad 1b formed on the mounting portion 1a via the metal member 6. Alternatively, the light-emitting element 5 is mounted and fixed on the mounting portion 1a via a brazing material or an adhesive, and the electrode 5a of the light-emitting element 5 is attached to an electrode pad 1b formed around the mounting portion 1a via wire bonding. It may be electrically connected.

  The electrode pad 1b is led out to the outer surface of the light emitting element storage package through a wiring layer (not shown) formed on the inside or the surface of the base 1, and external electric power is supplied through a brazing material, a metal lead or the like. By being connected to the circuit board, the light emitting element 5 and the external electric circuit are electrically connected.

  The metal member 6 is made of, for example, solder bumps using Au-tin (Sn) solder, Sn-Ag solder, Sn-Ag-Cu solder, Sn-lead (Pb), or a metal such as Au or Ag. It consists of metal bumps and the like, and is for mounting the light emitting element 5 on the substrate 1 by the flip chip bonding method. By mounting in such a flip chip bonding method, the electrode pad 1b can be provided immediately below the light emitting element 5 on the upper surface of the substrate 1, so that the periphery of the light emitting device 5 on the upper surface of the substrate 1 as in the wire bonding method. It is not necessary to provide the electrode pad 1b in the area. Therefore, it is possible to effectively suppress the light output emitted from the light emitting element 5 from being absorbed and radiated by the region of the electrode pad 1b of the base 1 to be lowered.

  The metal member 6 may have various volumes and shapes as shown in FIGS. 4A to 4C, but the volume of the metal member 6 is such that one end surface is the main surface of the electrode 5a. It is preferable that the other end surface occupies 70% by volume or more of the volume of the columnar space V (see FIG. 3) which is the main surface of the electrode pad 1b. Thereby, the heat conduction from the light emitting element 5 to the base 1 through the metal member 6 becomes very good, and the heat generated by the light emitting element 5 can be efficiently dissipated through the base 1 to the thermoelectric cooling medium 9 or the outside. Since it can do, the fall of the luminous efficiency of the light emitting element 5 resulting from a heat | fever can be suppressed effectively. Therefore, it is possible to suppress a decrease in light output of the light emitting device.

  Further, a thermoelectric cooling medium 9 is bonded to the lower surface of the substrate 1 with a bonding material such as solder, a brazing material such as Ag brazing, or a resin adhesive, and the light emitting element 5 is operated via the thermoelectric cooling medium 9. The generated heat is dissipated to the outside.

  The thermoelectric cooling medium 9 is a medium capable of obtaining the Peltier effect, and is provided with a thermoelectric cooling element 7 (Peltier element) or a plurality of thermoelectric cooling elements 7 as shown in FIG.

  In addition, it is preferable to lower the dew point by setting the atmosphere around the light emitting element 5 or the thermoelectric cooling medium 9 to a dry gas atmosphere, a reduced pressure gas atmosphere, a reduced pressure dry gas atmosphere, or the like. Thereby, in order to prevent dew condensation of the light emitting element 5 and the thermoelectric cooling medium 9, the temperature of the peripheral part of the light emitting element 5 and the peripheral part of the thermoelectric cooling medium 9 is changed to the peripheral part of the light emitting element 5 and the peripheral part of the thermoelectric cooling medium 9. While maintaining higher than the dew point, the temperature on the low temperature side of the thermoelectric cooling element 7 can be lowered to further improve the heat dissipation of the thermoelectric cooling medium 9. Therefore, it is possible to effectively suppress the increase in the temperature of the light emitting element 5 and to effectively reduce the function of the light emitting element 5 due to dew condensation or to cause deterioration of characteristics due to moisture due to dew condensation on the electronic components around the light emitting device. Can be prevented.

  When the light-emitting element 5 is mounted on the light-emitting element storage package, a light-transmitting lid is attached to the upper surface of the frame body 2, and the light-emitting element 5 is hermetically sealed to manufacture a light-emitting device. As for the atmosphere around the light emitting element 5 inside the light emitting device, for example, one or more holes are provided in the base 1, the frame 2, and the lid, and the inside of the light emitting device is evacuated or enclosed with dry gas After that, by sealing the hole, a dry gas atmosphere, a reduced pressure gas atmosphere, a reduced pressure dry gas atmosphere, or the like can be obtained. In addition to providing the hole in any of the base body 1, the frame body 2, and the lid body, a hole section communicating with the base body 1 and the heat cooling medium 9 may be provided.

  Further, the radiating fins 10 may be attached to the lower surface of the thermoelectric cooling medium 9. Further, as shown in FIG. 2, the heat radiation fin 10 is provided with a cavity a, and a cooling gas or a coolant is circulated in the cavity, thereby further improving the heat radiation effect of the thermoelectric cooling medium 9 and increasing the temperature of the light emitting element 5. May be further suppressed. Further, dew condensation on the thermoelectric cooling element 7 may be prevented by covering the periphery of the thermoelectric cooling element 7 with an insulator such as a resin.

  Further, a frame 2 made of metal, ceramics, resin, or the like is attached to the upper surface of the base 1 with a brazing material such as solder, Ag brazing, or an adhesive such as an epoxy resin. Furthermore, the frame 2 has a reflection surface 2b that can reflect the light emitted from the light emitting element 5 on the inner peripheral surface. As a method for forming such an inner peripheral surface, for example, the frame 2 is cut with a metal having high reflectivity such as Al, Ag, Au, platinum (Pt), titanium (Ti), chromium (Cr), or Cu. There is a method in which the inner peripheral surface is smoothed by a polishing process such as electrolytic polishing or chemical polishing to form the reflecting surface 2b. Further, the frame 2 is formed of Cu-W alloy or SUS (stainless steel) alloy having excellent weather resistance and moisture resistance, and a metal thin film is formed on the inner peripheral surface by metal plating such as Al, Ag or Au, or vapor deposition. May be formed. In the case where the inner peripheral surface is made of a metal that is easily discolored by oxidation such as Ag or Cu, the surface has a low melting point glass, a sol-gel glass, a silicone resin, or an excellent transmittance from the ultraviolet region to the visible light region. It is preferable to deposit an epoxy resin, whereby the corrosion resistance, chemical resistance, or weather resistance of the inner peripheral surface of the frame 2 can be improved.

  The arithmetic average roughness Ra of the inner peripheral surface of the frame body 2 is preferably 0.1 μm or less, so that the light emitted from the light emitting element 5 can be reflected well on the upper side of the light emitting device. it can. When Ra exceeds 0.1 μm, it becomes difficult to favorably reflect the light emitted from the light emitting element 5 to the upper side of the light emitting device on the inner peripheral surface of the frame body 2 and to easily diffuse the light inside the light emitting device. As a result, the loss of light inside the light emitting device tends to be large, and it becomes difficult to emit light outside the light emitting device at a desired radiation angle.

  In the light emitting element storage package of the present invention, the light emitting element 5 is mounted on the mounting portion 1 a of the base 1. For example, the light emitting element 5 is sealed by filling the translucent member 3 inside the frame 2. The light-emitting element 5 is accommodated by attaching a translucent lid to the upper surface or inner peripheral surface of the frame 2 so as to cover the light-emitting element 5 and hermetically sealing the light-emitting element 5. Light emitting device.

  The translucent member 3 is preferably made of a material having a small refractive index difference from the light emitting element 5 and a high transmittance for light emitted from the light emitting element 5 and the phosphor 4. For example, the translucent member 3 may be a transparent resin such as a silicone resin, an epoxy resin, or a urea resin, or a low-melting glass or a sol-gel glass. Thereby, it is possible to effectively suppress the occurrence of light reflection loss due to the difference in refractive index between the light emitting element 5 and the translucent member 3, and desired radiation intensity and angular distribution with high efficiency to the outside of the light emitting device. A light emitting device that can emit light can be provided. Moreover, such a translucent member 3 is filled inside the frame body 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.

  The translucent member 3 is an inorganic or organic phosphor that emits light in blue, red, green, yellow, or the like by recombination of electrons in the phosphor 4 excited by light emitted from the light emitting element 5. 4 may be blended and filled randomly in an arbitrary ratio. Thereby, the light which has a desired emission spectrum and color as a light-emitting device can be output.

  Further, in order to more effectively prevent moisture from penetrating through the translucent member 3 and causing dew condensation on the light emitting element 5 and its peripheral portion, the translucent member 3 is sandwiched between the upper surface of the translucent member 3 or the translucent member 3. In this way, it is preferable to dispose a transparent member such as glass that is light transmissive and airtight.

  The translucent lid is preferably made of glass or transparent resin and has a high transmittance with respect to light emitted from the light emitting element 5 or the phosphor 4.

  The translucent lid is an inorganic or organic fluorescent material that emits blue, red, green or yellow light by recombination of electrons in the phosphor 4 excited by the light emitted from the light emitting element 5. The body 4 may be blended and filled randomly at an arbitrary ratio. Alternatively, the phosphor 4 may be applied to the surface. Thereby, the light which has a desired emission spectrum and color as a light-emitting device can be output.

  The phosphor 4 is preferably formed so as to cover the light emitting element 5 in a layer with a constant thickness of 0.1 to 0.8 mm. For example, the phosphor 4 is contained by providing the translucent member 3 containing the phosphor 4 so that the distance from the light emitting portion of the light emitting element 5 to the surface of the translucent member 3 is 0.1 to 0.8 mm. A layer of translucent member 3 containing phosphor 4 having a thickness of 0.1 to 0.8 mm is provided on the surface of translucent member 3 or on the surface of the lid body by providing a lid body having a thickness of 0.1 to 0.8 mm. It can be formed by providing. Thereby, the light emitted from the light emitting element 5 is wavelength-converted with high efficiency by the phosphor 4 having a certain thickness, and the wavelength-converted light is effectively suppressed from being disturbed by the phosphor 4. Thus, the light can be efficiently emitted to the outside of the translucent member 3. As a result, the light output of the light emitting device can be increased and the illumination characteristics such as luminance and color rendering can be improved.

  When the thickness of the phosphor 4 layer is larger than 0.8 mm, even if the light emitted from the light emitting element 5 is wavelength-converted satisfactorily by the phosphor 4, the wavelength-converted light is efficiently transmitted to the outside of the light emitting device. Difficult to release well. That is, the progress of the wavelength-converted light is likely to be disturbed by the phosphor 4, and it is difficult to improve the light emission to the outside.

  On the other hand, when the thickness of the phosphor 4 layer is smaller than 0.1 mm, the number of the phosphors 4 that are irradiated and excited by the light emitted from the light emitting element 5 is reduced, and it is difficult to efficiently convert the wavelength. As a result, light having a wavelength with low visibility that is emitted without wavelength conversion increases, and it is difficult to improve illumination characteristics such as light output, luminance, and color rendering.

  The light emitting element 5 may have any peak wavelength of energy to be emitted from the ultraviolet region to the infrared region. However, from the viewpoint of emitting white light and light of various colors with good visibility, the light emitting element 5 has a wavelength of about 300 to 500 nm. It is preferable that the element emits light from ultraviolet to blue. For example, a gallium nitride-based compound semiconductor such as GaN, GaAlN, InGaN, or InGaAlN, or a silicon carbide-based compound semiconductor or ZnSe (selenide) in which a buffer layer, an n-type layer, a light-emitting layer, and a p-type layer are sequentially stacked on a sapphire substrate. Zinc) or the like in which the light emitting layer is formed.

  Examples of the light emitting device of the present invention are shown below.

  First, an alumina ceramic base made of crystal grains having various grain sizes (1, 5, 10, 15, 20 μm) to be the base 1 was prepared. In addition, an electrode pad 1b for electrically connecting the light emitting element 5 and the external electric circuit board through an internal wiring formed in the base 1 is formed on the mounting portion 1a on which the light emitting element 5 is mounted. did. The electrode pad 1b on the upper surface of the substrate 1 is formed into a circular pad having a diameter of 0.1 mm by a metallized layer made of Mo—Mn powder, and a Ni plating layer having a thickness of 3 μm and an Au pad having a thickness of 2 μm are formed on the surface. The plating layer was sequentially deposited. Further, the internal wiring inside the substrate 1 was formed by an electrical connection portion made of a through conductor, so-called through hole. This through hole was also formed of a metallized conductor made of Mo-Mn powder in the same manner as the electrode pad 1b. A thermoelectric cooling medium 9 was attached to the lower surface of the substrate 1.

  Next, the 0.08 mm thick light emitting element 5 that emits near-ultraviolet light having a peak wavelength at 382 nm is electrically connected to the electrode pad 1 b of the mounting portion 1 a via the metal member 6 made of Au—Sn. Connected to. The metal member 6 is prepared with a volume ratio of 30%, 50%, 70%, 90% with respect to the volume of the columnar space V between the electrode 5a and the electrode pad 1b of the light emitting element 5. did.

  Next, a silicone resin (translucent member 3) containing a phosphor 4 that emits yellow light by being excited by the light of the light emitting element 5 is coated around the light emitting element 5 by a dispenser and thermally cured to obtain a sample. A light emitting device was fabricated and the light output was measured.

  The phosphor 4 was uniformly dispersed at a filling rate (mass%) of 1/4 with respect to the silicone resin. The phosphor 4 used was a yttrium-aluminate-based phosphor emitting yellow light having a garnet structure with a particle size distribution of 1.5 to 80 μm.

  When the average grain size of the ceramic crystal grains of the substrate 1 was 20 μm, the light output was 14 mW. However, when the average grain size of the ceramic crystal grains of the substrate 1 is 1 to 15 μm, the light output is 17 mW or more, and the average grain size of the ceramic crystal grains is 20 μm. Increased by more than%. That is, as compared with the case where the average grain size of the ceramic crystal grains is 20 μm, the use of the base 1 having the average grain size of the ceramic crystal grains of 1 to 15 μm effectively suppresses light entering the base 1. At the same time, it is considered that the number of phosphors 4 irradiated with light by light scattering on the surface of the substrate 1 is increased and the light output is improved.

  In addition, when the current value is increased to increase the light output of the light emitting device, the substrate 1 having an average crystal grain size of 1 to 15 μm has a higher luminous efficiency with respect to the forward current than 20 μm. It was also confirmed that the decrease could be effectively suppressed.

  Moreover, the heat transfer efficiency from the light emitting element 5 to the base | substrate 1 was so favorable that the volume ratio of the metal member 6 increased with 30%, 50%, 70%, 90%. Cooling efficiency reached saturation at 70% or more.

  It should be noted that the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the scope of the present invention. For example, by joining an optical lens that can arbitrarily collect or diffuse light emitted from the light emitting device to the upper surface of the frame body 2 or a flat light-transmitting lid body with solder or an adhesive, Light can be taken out at a desired angle, and the water resistance to the inside of the light emitting device is improved, thereby improving long-term reliability. Further, the inner peripheral surface of the frame 2 may have a flat (straight) shape or an arc (curved) cross-sectional shape. In the case of the circular arc shape, light emitted from the light emitting element 5 can be uniformly reflected, and highly directional light can be uniformly emitted to the outside. Further, a plurality of light emitting elements 5 may be provided on the base 1 in order to increase the light output. Furthermore, it is also possible to arbitrarily adjust the angle of the inner peripheral surface of the frame body 2 and the distance from the upper end of the frame body 2 to the upper surface of the translucent member 3, thereby further providing a complementary color gamut. Good color rendering can be obtained.

It is sectional drawing which shows an example of embodiment about the light-emitting device of this invention. It is sectional drawing which shows the other example of embodiment about the light-emitting device of this invention. It is a figure for demonstrating the columnar body space in the light-emitting device of this invention. (A)-(c) is a principal part expanded sectional view which shows the various examples of the connection part of the light emitting element and a base | substrate in the light-emitting device of this invention. It is sectional drawing which shows the conventional light-emitting device. It is sectional drawing which shows the conventional light-emitting device.

Explanation of symbols

1: Base 1a: Placement part 1b: Electrode pad 2: Frame 5: Light emitting element 5a: Electrode 6: Metal member 7: Thermoelectric cooling element 9: Thermoelectric cooling medium V: Columnar space

Claims (3)

A base body made of ceramics having a mounting portion of a light emitting element on the upper surface and electrode pads formed on the mounting portion, and a frame attached to surround the mounting portion on the outer peripheral portion of the upper surface of the base body And a thermoelectric cooling medium attached to the lower surface of the substrate, wherein the substrate has an average grain size of 1 to 15 μm of crystal grains contained in the ceramics. Storage package. A light emitting device comprising: the light emitting element storage package according to claim 1; and the light emitting element mounted on the mounting portion and having an electrode electrically connected to the electrode pad. . In the light emitting element, the electrode is electrically connected to the electrode pad through a metal member, and the volume of the metal member is such that one end surface is the main surface of the electrode and the other end surface is the electrode. The light-emitting device according to claim 2, wherein the light-emitting device occupies 70% by volume or more of the volume of the columnar space defined as the main surface of the pad.

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