JP2004296575A - Package for housing light emitting element, and light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a package for housing a light emitting element which can increase the intensity and luminance of emitted light and has a superior heat dissipation performance, and which never causes cracking or peeling in the light emitting element and an adhesive. <P>SOLUTION: The package for housing a light emitting element comprises a sapphire substrate 1 which has a mounting part 1a to mount the light emitting element 3 in the center of the top face and has a metal layer 7 attached all over the bottom face, and a metal frame 2 whose internal surface is bonded to side faces of the substrate 1 over the entire circumference thereof so as to surround the mounting section 1a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light emitting element housing package for housing a light emitting element and a light emitting device.
[0002]
[Prior art]
FIG. 2 shows a conventional light emitting element housing package (hereinafter, simply referred to as a package) for housing a light emitting element 13 such as a light emitting diode (LED). In FIG. 2, the package has a mounting portion 11a for mounting the light emitting element 13 at the center of the upper surface, and lead terminals, metallized wiring, etc. for electrically connecting the inside and outside of the package from the mounting portion 11a and its periphery. A metal body having a base 11 made of an insulator on which a wiring conductor (not shown) made of a metal is formed, and a through hole 12a for accommodating the light emitting element 13 formed in the center at the center. And a frame 12 made of resin or ceramics.
[0003]
The base 11 is made of a ceramic such as an aluminum oxide sintered body (alumina ceramic), an aluminum nitride sintered body, a mullite sintered body, a glass ceramic, or a resin such as an epoxy resin. When the base 11 is made of ceramics, a metallized wiring is formed on the upper surface by firing 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, a lead terminal made of copper (Cu), iron (Fe) -nickel (Ni) alloy, or the like is molded and fixed inside the base 11.
[0004]
The frame 12 is made of a metal such as an aluminum (Al) or Fe-Ni-cobalt (Co) alloy, a ceramic such as an alumina sintered body, or a resin such as an epoxy resin, and is formed by cutting, molding or extrusion. It is formed by a molding technique such as molding. Further, a through hole 12a is formed at the center of the frame body 12 and extends outward as it goes upward. When the light reflectance of the inner peripheral surface of the through hole 12a is to be improved, this inner peripheral surface is formed. A metal such as Al is deposited by a vapor deposition method or a plating method. Then, the frame body 12 is joined to the upper surface of the base body 11 with a brazing material such as solder, silver brazing or the like or a resin adhesive so that the mounting portion 11a is surrounded by the inner peripheral surface of the through hole 12a.
[0005]
Then, the light emitting element 13 is joined to the mounting portion 11a with an adhesive 14 such as a conductive paste or a resin, and the electrodes of the light emitting element 13 and the wiring conductors arranged around the mounting portion 11a are bonded with bonding wires (not shown). Then, a transparent member 15 such as an epoxy resin or a silicone resin is filled into the inside of the frame 12 so as to cover the light emitting element 13 and thermally cured. Alternatively, a transparent member 15 made of a fluorescent material or a transparent resin mixed with a fluorescent material is applied around or on the surface of the light emitting element 13, and then the transparent member 15 is filled inside the frame body 12 and cured by heat to form a light emitting element. A light emitting device that can convert the wavelength of the light from 13 with a phosphor and extract light having a desired wavelength spectrum can be obtained. Then, a light-transmitting lid 16 is joined to the upper surface of the frame 12 with solder, a resin adhesive, or the like to form a light emitting device.
[0006]
[Patent Document 1]
JP-A-2002-232017
[Problems to be solved by the invention]
However, in the above-described conventional package, when the base 11 is made of ceramics such as alumina ceramics or aluminum nitride sintered body, light emitted from the light emitting element 13 or light irregularly reflected inside the package is absorbed by the base 11. Or permeate the substrate 11. As a result, there is a problem that the intensity and brightness of light transmitted from the light emitting element 13 through the lid 16 and emitted to the outside of the light emitting device are significantly deteriorated.
[0008]
In addition, in order to efficiently reflect the light of the light emitting element 13 above the base 11 and improve the intensity of emitted light and the luminance of the light emitting device, electrical conduction with a wiring conductor (not shown) of the mounting portion 11a is hindered. Attempts have been made to form a metal layer (not shown) on the inner peripheral surface of the frame 12 within a range that does not exist, and to efficiently reflect the light of the light emitting element 13 to the outside of the light emitting device. However, when a metal layer is formed on a substrate 11 made of ceramics having an arithmetic average roughness of about 0.5 μm by a conventional plating method or vapor deposition method, light from the light emitting element 13 is efficiently reflected and irradiated to a long distance. A degree of smoothness cannot be obtained on the surface of the metal layer. As a result, the brightness of the surface of the metal layer is improved, but the reflected light is scattered and the intensity distribution is dispersed, so that the intensity of emitted light is not improved.
[0009]
When the base 11 is made of glass having a smooth surface, a metal layer is formed on the upper surface or the lower surface to improve the reflectance, so that the intensity of emitted light and the luminance of the light emitting device can be improved. However, since the glass has a low thermal conductivity of 1 W / m · K, the heat of the light emitting element 13 cannot be sufficiently dissipated, and the temperature of the light emitting element 13 during operation increases. As a result, there is a problem that the internal quantum efficiency, which is the light extraction efficiency depending on the temperature at the time of operation of the light emitting element 13, is significantly deteriorated.
[0010]
When the light emitting element 13 in which a gallium nitride (GaN) crystal or the like is grown on a sapphire substrate to form a light emitting layer is mounted on a base 11 made of ceramics or resin, heat generated during operation of the light emitting element 13 causes a package to be mounted. The overall temperature rises, and the internal stress caused by the difference in the thermal expansion coefficient between the light emitting element 13 and the base 11 concentrates on the adhesive 14. As a result, cracks and peeling occur in the light emitting element 13 and the adhesive 14, and there is a problem that the light emitting device cannot be normally and stably operated for a long period of time.
[0011]
When the adhesive 14 is made of a conductive paste in which metal powder is mixed into a resin, the thermal conductivity of the adhesive 14 is significantly reduced due to corrosion of the metal powder due to moisture penetrating from gaps in the package. Rapidly rises, and the reflectance decreases due to corrosion of the metal layer. As a result, there is a problem that the internal quantum efficiency of the light emitting element 13 is significantly deteriorated, and the intensity of emitted light and the luminance of the light emitting device are significantly deteriorated.
[0012]
Accordingly, the present invention has been completed in view of the above-mentioned conventional problems, and its object is to improve the radiation light intensity and luminance and to have excellent heat dissipation, and to cause cracks and peeling of the light emitting element and the adhesive. There is no package and light emitting device to provide.
[0013]
[Means for Solving the Problems]
A light-emitting element housing package according to the present invention has a mounting portion on which a light-emitting element is mounted in a central portion of an upper surface and a base made of sapphire having a metal layer adhered to the entire lower surface, and the mounting on a side surface of the base. And a metal frame whose inner peripheral surface is joined over the entire periphery so as to surround the portion.
[0014]
The light-emitting element housing package of the present invention includes a base made of sapphire having a mounting part on which a light-emitting element is mounted at the center of the upper surface and a metal layer adhered to the entire lower surface, and a mounting part on a side surface of the base. And a frame made of metal whose inner peripheral surface is joined over the entire circumference so as to surround the light, the light of the light emitting element is efficiently reflected by the metal layer above the package and emitted from the light emitting device. Light emitted from the light-emitting device and the luminance of the light-emitting device can be improved.
[0015]
Further, since the base is made of sapphire whose thermal conductivity is about twice as large as that of alumina ceramics (thermal conductivity about 20 W / m · K), the heat generated from the light emitting element is diffused throughout the base and the light emitting device is mounted. Heat can be efficiently dissipated to the external electric circuit board. As a result, the temperature rise of the light emitting element can be suppressed, and the light emitting device can be normally and stably operated for a long time.
[0016]
Further , when the light-emitting element is formed of a sapphire substrate having a light-emitting layer formed thereon, the difference in thermal expansion coefficient between the light-emitting element and the base is almost eliminated, so that the thermal expansion of the light-emitting element and the base during operation of the light-emitting device is reduced. The internal stress caused by the coefficient difference is greatly reduced. As a result, cracks and peeling that occur in the bonding portion between the light emitting element and the base and in the light emitting element itself are effectively suppressed, and the light emitting device can be normally and stably operated for a long time.
[0017]
The semiconductor device housing package of the present invention is preferably characterized in that the arithmetic mean roughness of the lower surface of the base is 0.1 μm or less.
[0018]
In the package for accommodating a semiconductor element of the present invention, since the arithmetic mean roughness of the lower surface of the base is preferably 0.1 μm or less, the interface between the base and the metal layer has a highly reflective surface (specular reflection surface). (A smooth reflecting surface that reflects at the same angle as the angle). As a result, the light reflected by the metal layer can be efficiently reflected above the package, and the radiated light intensity and luminance of the light emitting device are significantly improved.
[0019]
The light-emitting device of the present invention includes a light-emitting element housing package of the present invention, a light-emitting element mounted on the mounting portion via an adhesive made of a transparent resin having the same refractive index as the base, and a light-emitting element. And a covering transparent member.
[0020]
With the above configuration, the light emitting device of the present invention can effectively suppress the reflection loss of light caused by the difference in refractive index between the base and the adhesive, and the light of the light emitting element passes through the base with low loss through the adhesive, The light is efficiently reflected by the metal layer and is extracted above the substrate. When the light emitting element is formed by forming a light emitting layer on a sapphire substrate, light loss is further reduced.
[0021]
Further, in the light emitting device of the present invention, preferably, the transparent member has the same refractive index as that of the base.
[0022]
In the light emitting device of the present invention, preferably, since the refractive index of the transparent member is the same as that of the base, reflection loss caused by a difference in the refractive index between the base and the transparent member in light reflected by the metal layer can be effectively suppressed, Light can be efficiently extracted to the outside of the light emitting element housing package via the transparent member.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
The light emitting element housing package of the present invention will be described in detail below. FIG. 1 is a cross-sectional view showing an example of a package according to an embodiment of the present invention, wherein 1 is a base, 2 is a frame, and 6 is a lid, and these mainly constitute a package for housing the light emitting element 3. Have been.
[0024]
The package according to the present invention has a base 1 made of sapphire having a mounting portion 1a for mounting the light emitting element 3 in the center of the upper surface and a metal layer 7 adhered to the entire lower surface, and a mounting portion 1a on the side surface of the base 1. And a frame 2 made of metal whose inner peripheral surface is joined over the entire periphery so as to surround the frame.
[0025]
The base 1 according to the present invention is made of sapphire, which is a hexagonal alumina (Al ₂ O ₃ ) single crystal, functions as a support member for supporting the light emitting element 3, and has a mounting portion 1a of the light emitting element 3 on its upper surface. Have. As a result, the heat generated from the light emitting element 3 can be diffused to the entire base 1 and the heat can be efficiently dissipated to the external electric circuit board on which the light emitting device is mounted, so that the temperature rise of the light emitting element 3 can be effectively suppressed. At the same time, the light emitting device can be normally and stably operated for a long time.
[0026]
The sapphire used for the base 1 has a central axis C axis and a plane orthogonal to the C axis, and a C plane. The A axis extending radially at 120 ° intervals from the C axis to the C plane and a plane orthogonal to the A axis. The plane A, which forms a certain angle (about 32.383 °) with the C axis, is the R plane, and the axis orthogonal thereto is the R axis. The side surface of the hexagonal crystal is the M plane, and the axis orthogonal to the M plane is the M axis. Note that these axes and planes can be analyzed and specified by an X-ray diffraction method.
[0027]
The base 1 is manufactured by an EFG method (Edge-defined Film-fed Growth method). With the EFG method, high-purity alumina is melted in an inert atmosphere, and a ribbon-shaped molybdenum die for growing a sapphire single crystal with a slit therein is positioned so as to be in contact with the alumina melt. Is guided to the upper end of the molybdenum die by capillary action, where it is brought into contact with a seed crystal (seed), and then the seed is pulled upward to grow sapphire. Then, the obtained sapphire is processed into a predetermined shape by a diamond wheel or the like by a cutting method.
[0028]
In the present invention, the arithmetic mean roughness of the lower surface of the base 1 is preferably 0.1 μm or less, and this roughness can be obtained by polishing the lower surface of the base 1. Polishing of the lower surface of the substrate 1 is performed by lapping using diamond abrasive grains, and precision polishing is performed while supplying a liquid in which spherical silica colloid particles (colloidal silica) are dispersed as a polishing liquid. When the arithmetic average roughness exceeds 0.1 μm, the light of the light emitting element 3 is diffused without specular reflection in the metal layer 7 formed on the entire lower surface of the base 1, and the intensity of radiated light above the package is significantly reduced. I do. As a result, the illuminance and luminous intensity on the irradiation surface of the light emitted from the light emitting device are reduced.
[0029]
The metal layer 7 effectively suppresses the transmission of light from the lower surface of the substrate 1 to the outside, and reflects the light to the upper side of the substrate 1 with high efficiency. It is formed by forming a high metal such as Al, Ag, Au, Pt, Cu, and Cr by a vapor deposition method, or by bonding a metal plate made of these metals with a transparent resin adhesive. Further, a metallized layer made of a metal powder such as W, Mo, Mn is formed as the metal layer 7, and a metal having excellent corrosion resistance such as Ni or gold (Au) having a thickness of about 1 to 20 μm is formed on the exposed surface of the metallized layer. The Ni plating layer and the Au plating layer can effectively prevent the metallized layer from being oxidized and corroded.
[0030]
Further, a lead terminal (not shown) made of a metal such as Cu or Fe-Ni alloy is joined to the metallized wiring (not shown) on the surface exposed to the outside of the base 1. A light emitting element 3 such as an LED or an LD is adhered to the mounting portion 1a with an adhesive 4 made of a transparent resin, and an electrode of the light emitting element 3 is provided with a bonding wire (not shown) on a metallized wiring around the mounting portion 1a. Electrically connected via the It is preferable that a metal having excellent corrosion resistance, such as Ni or Au, is applied to the exposed surface of the metallized wiring with a thickness of about 1 to 20 μm, so that the metallized wiring can be effectively prevented from being oxidized and corroded. The connection between the wiring and the light emitting element 3 via the bonding wire can be strengthened. Therefore, on the exposed surface of the metallized wiring, 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 by an electrolytic plating method or an electroless plating method. Is more preferable.
[0031]
The adhesive 4 preferably has the same refractive index as that of the substrate 1 made of sapphire, and more preferably, is made of a transparent resin having a high transmittance in the range from the ultraviolet region to the visible light region. Specifically, the adhesive 4 is made of a silicone resin, an epoxy resin, or the like. The reflection loss of light caused by the difference in the refractive index between the base 1 and the adhesive 4 can be effectively suppressed, and the light of the light emitting element 3 can be transmitted through the base 1 with a low loss through the adhesive 4 and efficiently by the metal layer 7. The light is reflected and taken out above the base 1. In addition, when the light emitting element 3 is formed by forming a light emitting layer on a sapphire substrate, light loss is further reduced, which is preferable.
[0032]
In addition, the frame 2 is formed so that the lower end portion of the inner peripheral surface is formed over the entire periphery so as to surround the mounting portion 1a on the side surface of the base 1, and solder, resin adhesive, Ag paste, glass frit having a melting point of 250 ° C. or more. And the like. As a result, the light-emitting device can maintain airtightness for a long period of time, and can effectively suppress deterioration or breakage of the characteristics of the light-emitting element 3 due to permeation of moisture or the like, and light loss or light scattering due to the attachment of water droplets to the lid 6. Furthermore, it is preferable to form a through-hole that extends outward as the inner peripheral surface goes upward at the center of the frame 2. As a result, the light of the light emitting element 3 is reflected by the inner peripheral surface of the frame 2 at a desired emission angle and intensity distribution, and can be efficiently emitted to the outside of the package.
[0033]
The frame 2 is made of a metal such as Al, Ag, Au, Pt, Cu, and Cr, which has a high reflectance with respect to light in the ultraviolet region to the visible region. Then, the transparent member 5 is filled inside the frame 2 and cured by heat to form a transparent coating layer covering the light emitting element 3, and the light-transmissive lid 6 is attached to the upper surface of the frame 2 by soldering or resin adhesive. And so on.
[0034]
The transparent member 5 preferably has the same refractive index as that of the substrate 1, and more preferably has a high transmittance for light in the ultraviolet region to the visible light region. For example, the transparent member 5 is made of a transparent resin such as an acrylic resin or a polycarbonate. This effectively suppresses the occurrence of light reflection loss due to the difference in the refractive index between the base 1 and the transparent member 5 and emits light with high efficiency and a desired radiation light intensity and angle distribution to the outside of the package. Equipment can be manufactured.
[0035]
The lid 6 is made of a translucent material such as glass, sapphire, quartz, or a resin (plastic) such as an epoxy resin, a silicone resin, or an acrylic resin. In addition to protecting the wiring, bonding wires, and the transparent member 5 covering the light emitting element 3, the inside of the package is hermetically sealed. Further, by forming the lid 6 into a lens shape and adding the function of an optical lens, the light of the light emitting element 3 is condensed or dispersed, and the light of the light emitting element 3 is extracted out of the package at a desired radiation angle and intensity distribution. be able to.
[0036]
Thus, in the package of the present invention, the light emitting element 3 is bonded to the mounting portion 1a of the base 1 with the adhesive 4 made of a transparent resin, and the light emitting element 3 is connected to the external electric circuit outside the package via the bonding wire and the metallized wiring. After that, the transparent member 5 is filled inside the frame 2 to form a transparent coating layer covering the light emitting element 3, and the light-transmissive lid 6 is placed on the upper surface of the frame 2. A light emitting device is obtained by joining with solder or resin adhesive. After applying a phosphor or a transparent resin mixed with a phosphor to the periphery or the surface of the light emitting element 3, a transparent member 5 covering the light emitting element 3 is filled, and a transparent cover 6 is provided on the upper surface of the frame 2. Are joined by solder, resin adhesive, or the like, whereby the light of the light emitting element 3 is converted into a wavelength by the fluorescent material, and a light having a desired wavelength spectrum can be extracted.
[0037]
It should be noted that the present invention is not limited to the above embodiment, and that various changes may be made without departing from the scope of the present invention. Further, in order to suppress light loss due to the bonding wire, a light emitting device may be formed by forming a metallized wiring on the mounting portion 1a and electrically connecting the light emitting element 3 to the metallized wiring via solder.
[0038]
【The invention's effect】
The light-emitting element housing package of the present invention includes a base made of sapphire having a mounting part on which a light-emitting element is mounted at the center of the upper surface and a metal layer adhered to the entire lower surface, and a mounting part on a side surface of the base. And a frame made of metal whose inner peripheral surface is joined over the entire circumference so as to surround the light, the light of the light emitting element is efficiently reflected by the metal layer above the package and emitted from the light emitting device. Light emitted from the light-emitting device and the luminance of the light-emitting device can be improved.
[0039]
Further, since the base is made of sapphire whose thermal conductivity is about twice as large as that of alumina ceramics (thermal conductivity of about 20 W / m · K), the heat generated in the light emitting element is diffused throughout the base and the light emitting device is mounted. Heat can be efficiently dissipated to the external electric circuit board. As a result, the temperature rise of the light emitting element can be suppressed, and the light emitting device can be normally and stably operated for a long time.
[0040]
Further, when the light-emitting element is formed of a sapphire substrate having a light-emitting layer formed thereon, the difference in thermal expansion coefficient between the light-emitting element and the base is almost eliminated, so that the thermal expansion of the light-emitting element and the base during operation of the light-emitting device is reduced. The internal stress caused by the coefficient difference is greatly reduced. As a result, cracks and peeling that occur in the bonding portion between the light emitting element and the base and in the light emitting element itself are effectively suppressed, and the light emitting device can be normally and stably operated for a long time.
[0041]
In the package for housing a semiconductor element of the present invention, since the arithmetic average roughness of the lower surface of the base is preferably 0.1 μm or less, the interface between the base and the metal layer can be a regular reflection surface having a very high reflectance. As a result, the light reflected by the metal layer can be efficiently reflected above the package, and the radiated light intensity and luminance of the light emitting device are significantly improved.
[0042]
The light emitting device of the present invention includes a light emitting element housing package of the present invention, a light emitting element mounted on a mounting portion via an adhesive made of a transparent resin having the same refractive index as a substrate, and a transparent member covering the light emitting element. By having, the reflection loss of light caused by the difference in the refractive index between the substrate and the adhesive can be effectively suppressed, and the light of the light emitting element can be transmitted through the substrate with low loss through the adhesive, and the metal layer The light is efficiently reflected and taken out above the substrate. When the light emitting element is formed by forming a light emitting layer on a sapphire substrate, light loss is further reduced.
[0043]
In the light emitting device of the present invention, preferably, since the refractive index of the transparent member is the same as that of the base, reflection loss caused by a difference in the refractive index between the base and the transparent member in light reflected by the metal layer can be effectively suppressed, Light can be efficiently extracted to the outside of the light emitting element housing package via the transparent member.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an example of an embodiment of a light emitting element housing package of the present invention.
FIG. 2 is a cross-sectional view of a conventional light emitting element storage package.
[Explanation of symbols]
1: Base 1a: Mounting part 2: Frame 3: Light emitting element 4: Adhesive 5: Transparent member 6: Lid 7: Metal layer

Claims (4)

A base made of sapphire having a mounting portion on which a light emitting element is mounted in the center of the upper surface and a metal layer attached to the entire lower surface, and an inner peripheral surface surrounding the mounting portion on a side surface of the base. A light-emitting element housing package comprising: a metal frame joined over the entire periphery. The package according to claim 1, wherein the base has an arithmetic average roughness of 0.1 μm or less on a lower surface. 3. The light-emitting element storage package according to claim 1, wherein the light-emitting element is mounted on the mounting portion via an adhesive made of a transparent resin having the same refractive index as that of the base, and covers the light-emitting element. A light-emitting device comprising a transparent member. The light emitting device according to claim 3, wherein the refractive index of the transparent member is the same as that of the base.

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