Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages
  • H10H20/858—Means for heat extraction or cooling
  • H10H20/8581—Means for heat extraction or cooling characterised by their material
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages
  • H10H20/855—Optical field-shaping means, e.g. lenses
  • H10H20/856—Reflecting means
• • H10W72/5363—
• • H10W90/00—
• • H10W90/724—
• • H10W90/754—

Definitions

• the present invention relates to a light emitting device in which a light emitting element such as a light emitting diode (LED) or a semiconductor laser is mounted on the surface of an insulating substrate, and particularly has a simple manufacturing process and excellent heat dissipation.
• the present invention relates to a light-emitting device capable of flowing a larger current, having high luminous efficiency and capable of significantly increasing luminance, and a lighting fixture or a liquid crystal display device using the light-emitting device.
• a light-emitting diode (hereinafter also referred to as an LED chip) is a light-emitting element that acts as a light source when a voltage is applied. It regenerates electrons and holes near the contact surface (pn junction) of two semiconductors. It is a light-emitting element that utilizes light emitted by coupling. Because this light-emitting element is small and has high conversion efficiency to light, it is widely used as home appliances, lighting fixtures, illuminated operation switches, and LED displays.
• FIG. 2 As a conventional light-emitting device on which a light-emitting element such as the above-described LED chip is mounted, for example, a light-emitting device shown in FIG. 2 has been proposed (see, for example, Patent Document 1).
• This light-emitting device 1 is electrically connected to the conductor wiring 2 via a bonding wire 4 in a ceramic package 3 in which a conductor wiring 2 is arranged and a large number of concave openings are integrally formed.
• the LED chip 5 as a connected light emitting element, the first metal layer 6 and the second metal layer 7 formed on the side wall of the concave opening, and the resin mold 8 for sealing the concave opening. And is composed of.
• the first metal layer 6 provided in the concave opening improves the adhesion with the ceramic package 3, and the light from the LED chip 5 is transmitted to the second metal layer. Reflected by layer 7, light loss can be reduced, and contrast of display etc. can be improved
• Patent Document 1 Japanese Patent No. 3316838
• the ceramic package with the LED chip is mainly made of alumina (Al 2 O 3), and the thermal conductivity is 15 to 20 W / m'K.
• the heat conductivity is low, it is made of a ceramic material, and the heat conductivity of the resin mold that seals the LED chip is low. Therefore, if a high voltage or high current is applied, the LED chip will be destroyed by heat generation. Therefore, the current value at which the voltage that can be applied to the LED chip is low is also limited to about several tens of mA, which causes a problem of low emission luminance.
• the conventional light-emitting device uses a ceramic package integrally formed with a large number of concave openings for accommodating light-emitting elements, which complicates the manufacturing process and has a configuration.
• the finish accuracy of parts was low and sufficient light emission characteristics could not be obtained. That is, there is a problem that a machining operation for integrally forming a large number of concave openings in a hard and brittle ceramic material is extremely difficult and requires a great number of machining steps.
• the side surface of the concave opening that accommodates the light emitting element functions as a light reflector (reflector). Since the reflector is formed integrally with the ceramic substrate body, The surface roughness of the inner wall of the fretater was as rough as 0.5 m-Ra, and there was a problem that light scattering was likely to occur. Moreover, in order to control the light reflection direction, even if an inner wall surface of the reflector is given a constant inclination angle, it is difficult to stably obtain a constant inclination angle with a large variation in the inclination angle. In any case, it has been difficult to control the shape accuracy of the concave opening. In addition, even when trying to adjust to a predetermined finish accuracy, there was a problem that the number of man-hours that hard to work with ceramic materials would increase significantly.
• the light emission of the LED chip force is concave.
• the light emission efficiency was reduced due to absorption by the inner wall of the opening, resulting in a decrease in luminous efficiency. Therefore, in the known example, two metal layers that reflect light are formed on the inner wall of the concave opening to reduce light absorption loss.
• the inner wall of the opening itself has a structure that prevents the light from traveling.
• the present invention has been made to solve the above-described conventional problems.
• the manufacturing process is simple, the heat dissipation is excellent, a larger current can flow, the luminous efficiency is high, and the luminance is greatly increased.
• An object is to provide a light emitting device capable of increasing the number of calories.
• the present invention is a light emitting device in which at least one light emitting element is mounted on a surface of a co-fired substrate having an aluminum nitride force by a flip chip method.
• a reflector (light reflector) having an inclined surface that reflects light emitted from the light emitting element force in a front direction is bonded to the surface of the aluminum nitride substrate so as to surround the light emitting element.
• the light-emitting element may be supplied with power through the internal wiring layer of the aluminum nitride substrate.
• the printed wiring board includes a through hole immediately below the aluminum nitride substrate, and a heat sink having a convex portion fitted into the through hole is closely bonded to the back surface of the aluminum nitride substrate. It is preferable to do.
• the surface of the aluminum nitride substrate on which the light-emitting element is mounted is mirror-polished so as to have a surface roughness of 0.3 ⁇ mRa or less.
• a metal film made of aluminum or silver is formed on the inclined surface of the reflector.
• A1N substrate it is preferable to use an A1N substrate having a thermal conductivity of 170 W / m ⁇ K or more.
• the heat dissipation of the light-emitting device is greatly increased, the current-carrying limit of the light-emitting element is increased, and a large current can flow, so that the light emission luminance is increased. It becomes possible to raise it significantly.
• the reflector (light reflector) has an inclined surface that reflects light emitted from the light emitting element in the front direction.
• a metal material such as Kovar alloy or copper (Cu) is used as ABS. It is formed of a greave material such as fat.
• This reflector is not formed integrally with the A1N substrate body, but is prepared in advance as a separate component such as metal or grease, and then joined to the surface of the aluminum nitride substrate so as to surround the light emitting element. . Therefore, it is possible to control the finisher surface roughness, dimensions, reflection surface inclination angle, etc. with high precision. It is possible to mass-produce a reflector with excellent reflection characteristics in a simple process.
• the inner wall surface (inclined surface) of the reflector can be easily mirror-polished, and the angle of the inclined surface can be precisely controlled.
• a printed wiring board in which wiring is connected to electrode pads installed on the outer peripheral portion of the back surface of the aluminum nitride substrate is disposed on the back surface of the aluminum nitride substrate, and the internal wiring of the aluminum nitride substrate from the printed wiring board
• the light emitting element is mounted on the surface of the co-fired substrate having an aluminum nitride force by a flip chip method, the light emitting element is energized from the electrode formed on the back surface of the aluminum nitride substrate to the internal wiring layer.
• the light emitting element on the surface side is formed through This simplifies the wiring structure that does not require the wiring to be connected by the wire bonding method on the surface side of the A1N substrate, and does not protrude in the thickness direction of the bonding wire. Thin and compact.
• the printed wiring board has a through hole immediately below the aluminum nitride substrate, while a heat sink having a convex portion fitted into the through hole is closely attached to the back surface of the aluminum nitride substrate.
• the reflectance on the polished surface is increased, and the light emitted from the bonding surface side force of the light emitting element is effectively reflected to the A1N substrate surface side.
• the emission intensity (luminance) can be substantially increased.
• the surface roughness of the mirror polished surface is 0.3 mRa or less based on the arithmetic average roughness (Ra) standard defined by Japanese Industrial Standard CFIS B0601). When this surface roughness is roughened to exceed 0.3 mRa, the light emission intensity is likely to be lowered, which is likely to cause irregular reflection and absorption of light emission on the polished surface.
• the surface roughness of the mirror-polished surface is set to 0.3 ⁇ mRa or less.
• the reflectance of light emission can be further increased.
• the light emission intensity in the front direction of the light emitting device can be increased. Can do.
• a metal film having a reflectance of light emission from the light emitting element of 90% or more on the inclined surface light emitted from the side of the light emitting element is effectively reflected by the metal film and inverted to the front side.
• the metal film having a reflectance of 90% or more is preferably composed of aluminum or silver. This metal film is formed by chemical vapor deposition (CVD) or sputtering so as to have a thickness of about 1 to 5 ⁇ m, preferably 1 to 3 ⁇ m.
• the reflectance is given by the ratio of the emission intensity of reflected light to the emission intensity of incident light.
• the light emitting element is formed.
• an electrode plate or the like is not necessary, so that light can be extracted from the entire back surface of the light emitting element.
• the arrangement pitch between the light emitting elements can be reduced, the mounting density of the light emitting elements is increased, and the light emitting device can be downsized.
• a metal bump such as a solder bump is formed at a connection end of a light emitting element such as an LED chip, and this bump is formed on the back surface of the substrate via a land provided at a via hole and an end of a wiring conductor. It is possible to perform face-down wiring that connects to the energized wiring of the printed circuit board. According to this face-down wiring structure, any position force electrode on the surface of the light emitting element can be taken out, so that the light emitting element and the wiring conductor can be connected in the shortest distance, and the number of electrodes As the LED increases, the size of the LED chip as a light-emitting element does not increase, and the mounting force and ultra-thin mounting become possible.
• the substrate (LED package) on which the LED chip is mounted has a high thermal conductivity and uses an aluminum nitride (A1N) cofire substrate (co-fired substrate).
• A1N aluminum nitride
• the heat dissipation of the light-emitting device is greatly increased, and the current-carrying limit is increased. Since it becomes possible to flow an electric current, it is possible to greatly increase the light emission luminance.
• the reflector 1 is not formed integrally with the A1N substrate body, but is prepared as a separate component in advance and then joined to the surface of the aluminum nitride substrate. Therefore, it is easy to apply force at the parts stage, and the finisher surface roughness, dimensions, reflection surface inclination angle, etc. of the reflector can be controlled with high precision, and a reflector with excellent reflection characteristics can be obtained. The emission efficiency of emitted light can be increased. Furthermore, since the light-emitting element is mounted and connected to the A1N substrate by the flip-chip method, it is possible to extract the entire back surface of the light-emitting element. In addition, since the arrangement pitch between the light emitting elements can be reduced, the mounting density of the light emitting elements is increased, and the light emitting device can be downsized.
• FIG. 1 is a sectional view showing an embodiment of a light emitting device according to the present invention. That is, the light-emitting device 11 according to this embodiment is a light-emitting device in which three LED chips 15 as light-emitting elements are mounted on the surface of a co-fired substrate (A1N multilayer substrate) 13 made of aluminum nitride by the flip-chip method.
• the Kovar reflector 16 having an inclined surface 14 that reflects light emitted from the LED chip 15 as the light emitting element in the front direction surrounds the LED chip 15 so that the surface of the aluminum nitride substrate 13 Solder-bonded to each other.
• the thermal conductivity is 200W / m'K
• the two-layer co-fired A1N multi-layer substrate of length 5mm x width 5mm x thickness 0.5mm is used. It was.
• a printed wiring board 19 whose wiring is connected to the electrode pads 17 provided on the outer peripheral portion of the back surface of the aluminum nitride substrate 13 is disposed on the back surface of the aluminum nitride substrate 13.
• An electrode pad for flip chip connection is formed on the surface side of the aluminum nitride substrate 13, and this electrode pad is conducted to the internal wiring layer 12 of the aluminum nitride substrate 13 through a via hole.
• the internal wiring layer 12 is routed from the electrode pad at the center of the A1N board 13 to the outer periphery of the A1N board. Connection electrode pads 17 are formed.
• Bumps made of Au, A1, and solder are formed on the flip chip connecting electrode pads on the surface of the aluminum nitride substrate 13, and the LED chip is bonded via the bumps.
• the printed wiring board 19 is also supplied with power to the LED chip 15 via the electrode pad 17, via hole, and internal wiring layer 12.
• the printed wiring board 19 has a through hole 20 immediately below the aluminum nitride substrate 13, and the back surface of the A1N substrate 13 is exposed to the through hole 20.
• a copper heat sink 21 having a convex portion 21a that fits into the through hole 20 is joined to the back surface of the aluminum nitride substrate 13 so as to be in close contact with heat radiating grease or solder.
• the internal space of the reflector 16 is filled with a phosphor 22 that emits light of a predetermined wavelength by light emission from the LED chip 15 and a mold resin 18.
• the LED chip 15 when the LED chip 15 is energized from the printed wiring board 19 through the electrode pad 17, via hole, and internal wiring layer 12, the LED chip 15 emits light, and this light emission Is irradiated onto the phosphor 22 to emit light of a specific wavelength.
• the light emitted from the side surface of the LED chip 15 is reflected by the inclined surface 14 of the reflector 16 and is emitted in the front direction.
• the surface of the aluminum nitride substrate 13 on which the LED chip 15 is mounted is mirror-polished so as to have a surface roughness of 0.3 mRa or less, it is emitted toward the back surface of the LED chip 15.
• the reflected light is reflected on the surface of the aluminum nitride substrate 13. Therefore, the brightness of the light emitted in the front direction of the light emitting device 11 can be increased.
• the heat released from the heated LED chip 15 can be quickly dissipated in the direction of the heat sink 21 via the aluminum nitride substrate 13. Therefore, in combination with the heat transfer effect of the A1N substrate 13 having high thermal conductivity, the heat dissipation of the light emitting device 11 can be greatly enhanced.
• the reflector 16 is made of a Kovar alloy, the inclined surface 14 can be formed extremely smoothly and has a sufficient light reflection function.
• a metal film made of silver (Ag) or aluminum (A1) on the inclined surface 14 by chemical vapor deposition or the like, the light reflection characteristics of the reflector 16 can be further enhanced.
• the aluminum chip (A1N) cofire substrate sinultaneously fired substrate with high thermal conductivity is used as the substrate (LED package) on which the LED chip 15 is mounted. Therefore, the heat dissipation of the light-emitting device 10 is greatly increased, the current limit of the LED chip is increased, and a large current can flow. It became possible.
• the reflector 16 is not formed integrally with the A1N substrate body, but is prepared as a separate component in advance and then joined to the surface of the aluminum nitride substrate 13. Therefore, by processing at the component stage, the finish roughness, dimensions, inclination angle of the inclined surface (light reflecting surface) 14, etc. can be controlled with high precision, and the reflector 16 with excellent reflection characteristics can be obtained. As a result, it was possible to increase the light emission efficiency.
• the LED chip 15 is mounted and connected to the A1N substrate 13 by the flip chip method, the entire back surface force of the LED chip 15 can extract light. Further, since the arrangement pitch between the LED chips 15 can be reduced, the mounting density of the LED chips 15 is increased, and the light emitting device 11 is downsized.
• a printed wiring board 19 whose wiring is connected to the electrode pad 17 provided on the outer periphery of the back surface of the aluminum nitride substrate 13 is disposed on the back surface of the aluminum nitride substrate 13, and from the printed wiring board 19.
• the LED chip 15 is mounted on the surface of the co-fired substrate 13 that also has aluminum nitride force by the flip chip method, the current to the LED chip 15 is formed on the back surface of the aluminum nitride substrate 13.
• the electrode pads 17 are applied to the LED chip 15 on the surface side through the internal wiring layer 12. This simplifies the wiring structure that eliminates the need to connect the wires by the wire bonding method on the surface side of the A1N substrate 13, and also provides a bonder. Since there is no protrusion in the thickness direction of the ing wire, the light emitting device 11 can be formed thin and small.
• the printed wiring board 19 has a through hole 20 immediately below the aluminum nitride substrate 13, and a heat sink 21 having a convex portion 21 a fitted into the through hole 20 is in close contact with the back surface of the aluminum nitride substrate 13.
• Example 2 is the same as Example 1 except that a 2 m thick metal film 23 having a silver (Ag) force is formed on the inclined surface 14 of the reflector 16 shown in FIG. A light emitting device was prepared.
• a light emitting device according to Example 3 was prepared in the same manner as in Example 1 except that the heat sink 21 shown in FIG.
• a flat heat sink 21 having no protrusion 21a shown in FIG. 1 is processed in the same manner as in Example 1 except that it is joined to the A1N substrate 13 through a printed wiring board that does not form a through hole.
• Example 4 A light emitting device according to was prepared.
• Table 1 below shows the average values obtained by measuring the thermal resistance values, the LED conduction limit amounts, and the light emission luminances of ten light emitting devices according to the respective examples prepared as described above.
• the inclined surface 14 of the reflector 16 further has silver ( According to the light emitting device according to Example 2 in which the metal film 23 made of (Ag) is formed, the light reflectance at the inclined surface 14 is further increased and the light emission luminance is improved by 10 to 20% as compared with Example 1. There was found.
• the thermal resistance value is increased 18 times compared to Examples 1 and 2, and the LED energization limit amount and the light emission luminance are relatively high. Declined.
• a light fixture was prepared by assembling the light emitting device according to Examples 1 and 2 above to a lighting fixture body, and further arranging a lighting device on the fixture body. It was confirmed that each lighting fixture has excellent heat dissipation characteristics, can pass a larger current (the limit of LED energization), has high luminous efficiency, and can greatly increase brightness. .
• a linear light source can be obtained by arranging a plurality of light emitting devices as shown in FIG. 1 in rows or columns in the vertical or horizontal direction, while a plurality of light emitting devices are arranged two-dimensionally in the vertical and horizontal directions.
• a surface-emitting light source was obtained effectively.
• a liquid crystal display device was assembled by arranging a liquid crystal display device (LCD) main body and the light emitting device according to Examples 1 and 2 as a backlight on the main body of the device.
• Each liquid crystal display (LCD) uses an A1N substrate with excellent heat dissipation as the substrate of the light-emitting device. It is highly efficient and the brightness of the display device can be greatly increased.
• the thermal conductivity is 200 W / m ⁇ K and 2
• the thermal resistance was reduced by about 20-30%, and the current-carrying limit and emission luminance could be increased by about 20-30%.
• the substrate (LED package) on which the LED chip is mounted has high thermal conductivity! Aluminum nitride (A1N) cofire substrate (co-fired substrate) ) Is used, the heat dissipation of the light emitting device is greatly increased, the current supply limit is increased, and a large current can flow. Therefore, the light emission luminance can be significantly increased.
• A1N Aluminum nitride
• the reflector 1 is not formed integrally with the A1N substrate body, but is prepared as a separate component in advance and then joined to the surface of the aluminum nitride substrate. Therefore, it is easy to apply force at the parts stage, and the finisher surface roughness, dimensions, reflection surface inclination angle, etc. of the reflector can be controlled with high precision, and a reflector with excellent reflection characteristics can be obtained. The emission efficiency of emitted light can be increased. Furthermore, since the light-emitting element is mounted and connected to the A1N substrate by the flip-chip method, it is possible to extract the entire back surface of the light-emitting element. In addition, since the arrangement pitch between the light emitting elements can be reduced, the mounting density of the light emitting elements is increased, and the light emitting device can be downsized.
• FIG. 1 is a cross-sectional view showing an embodiment of a light emitting device according to the present invention.
• FIG. 2 is a cross-sectional view illustrating a configuration example of a conventional light emitting device.

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