JP2004228239A - Package for storing light emitting element and light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a stable light emitting device which can satisfactorily reflect light that a light emitting element emits on an inner face of a frame body, can uniformly and efficiently radiate light to an outer part and which is superior in an optical characteristic such as a radiation angle of light and light intensity distribution. <P>SOLUTION: A package for storing light emitting element is provided with a ceramic substrate 2 having a mounting part 2a mounting the light emitting element 5 in a center part on an upper face, a first frame body 4 which is connected to an outer peripheral part at an upper face of the substrate 2 by surrounding the mounting part 2a and is formed of metal inclined so that an inner face extends toward an outer side and a ceramic second frame body 6 connected to an upper face of the first frame body 4. <P>COPYRIGHT: (C)2004,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]
Conventionally, light-emitting devices using light-emitting elements such as light-emitting diodes (LEDs) and semiconductor lasers (LDs) have been attracting attention in the future as having lower power consumption and longer life, and have recently been used in various fields. Has begun. FIG. 2 is a cross-sectional view of a light emitting element housing package (hereinafter, also referred to as a package) on which a conventional light emitting element is mounted.
[0003]
As shown in FIG. 2, a conventional package 11 has a base 12 made of various resins, ceramics and the like. A conductive paste containing tungsten (W), molybdenum (Mo), manganese (Mn), or the like is sintered at a high temperature on the base 12, and a nickel (Ni) plating layer or a gold (Au) plating layer is formed on the upper surface thereof by a plating method. Is formed on the wiring conductor 13. Via the wiring conductor 13, it is connected so that electric power and drive current can be supplied from the outside to the light emitting element 15 mounted inside the package.
[0004]
The base 12 is provided with a frame 14 made of various resins and ceramics and having a through-hole passing through the upper and lower surfaces and having a square shape in a plan view on one main surface on the inner side of the package 11. Is fixed with a brazing material such as silver (Ag) -copper (Cu) having a melting point of 700 to 900 ° C., various resin adhesives, a high melting glass (low melting glass), or the like.
[0005]
The light emitting element 15 is die-bonded to the base 12 with an adhesive made of Ag paste or a resin adhesive, and the electrode of the light emitting element 15 is wire-bonded to the wiring conductor 13 provided on the base 12 by a bonding wire made of Au.
[0006]
Further, a transparent member 18 is provided inside the frame 14 to protect the light emitting element 15. The transparent member 18 can be provided by filling the inside of the frame body 14 with a thermosetting epoxy resin or the like so as to cover the light emitting element 15 and heating and curing the resin. The transparent member 18 also has a function of firmly adhering to the light emitting element 15, the base 12, and the frame body 14 to firmly fix the light emitting element 15 in the package 11. Further, a transparent and plate-shaped lid 17 made of glass, sapphire, or the like is adhered to the upper surface of the frame 14 with a resin adhesive or the like. Thus, a light emitting device having the light emitting element 15 is obtained.
[0007]
In this light emitting device, the light emitting element 15 is activated by a drive current supplied from an external electric circuit, and is used to emit visible light. Its applications are various indicators, optical sensors, displays, photocouplers, backlights, optical printer heads, and the like.
[0008]
In recent years, this light-emitting device has been used for lighting, and a light-emitting device having higher characteristics in terms of high luminance and heat dissipation has been demanded. In addition, when used for lighting, extending the life of the light emitting device is a particularly important problem.
[0009]
Therefore, recently, a configuration for improving the light emission luminance of the light emitting device has been considered, and the frame 14 is often made of a material having higher reflectance. For example, the light emitted from the light emitting element 15 may be formed by forming the frame 14 from a metal having a high reflectance such as silver (Ag) or aluminum (Al), or by attaching the metal to the surface of the frame 14. Is efficiently radiated to the outside of the package 11.
[0010]
[Patent Document 1]
JP 2002-344029 A
[Problems to be solved by the invention]
However, the conventional package 11 has a problem that heat generated from the light emitting element 15 causes distortion in the package 11 and makes it difficult to stabilize a radiation angle of light emitted by the light emitting element 15. This is caused, for example, by a difference in the coefficient of thermal expansion between the base 12 and the frame 14 because the base 12 is made of resin or ceramic and the frame 13 is made of metal. Therefore, the conventional package 11 can sufficiently cope with high luminance. However, if the power (electric power) input to the light emitting element 15 is increased in order to increase the luminance, the light emitted from the light emitting element 15 becomes more stable. There is a new problem that the radiation angle, light intensity distribution and the like cannot be obtained. In the future, when used for applications such as local illumination, the radiation angle of light is an important issue. There is a need for a light emitting device that is excellent in optical characteristics such as the light emission angle and light intensity distribution and is stable.
[0012]
Therefore, the present invention has been completed in view of such a conventional problem, the purpose of which is to allow the light emitted by the light emitting element to be reflected efficiently on the inner surface of the frame, and to be uniformly and efficiently emitted to the outside, Another object of the present invention is to provide a package and a light-emitting device which can manufacture a stable light-emitting device having excellent optical characteristics such as a light emission angle and a light intensity distribution.
[0013]
[Means for Solving the Problems]
The package for housing a light emitting element of the present invention comprises a base body made of ceramics having a mounting part conductor layer for mounting the light emitting element in the center part of the upper surface, and an outer peripheral part of the upper surface of the base body, which surrounds the mounting part and is joined to the inner surface. And a second frame made of ceramics joined to an upper surface of the first frame, the first frame being made of metal inclined so as to spread outward.
[0014]
The light-emitting element housing package of the present invention has a first frame body made of metal that is joined to the outer peripheral portion of the upper surface of the base body so as to surround the mounting portion conductive layer and that the inner surface is inclined so as to expand outward. Accordingly, light emitted from the light-emitting element can be reflected out of the light-emitting element housing package by 80% or more, so that a light-emitting device with high luminance can be manufactured. Further, since the second frame made of ceramics is provided, the first frame is prevented from being deformed due to a difference in thermal expansion coefficient between the base made of ceramics and the first frame made of metal. This makes it possible to manufacture a light-emitting device having excellent and stable optical characteristics such as light emission angle and light intensity distribution.
[0015]
The light emitting device according to the present invention includes a light emitting element housing package according to the present invention, a light emitting element mounted on the mounting portion conductive layer, and the light emission inside the first frame or above the second frame. A light-transmitting member provided on the optical axis of the element.
[0016]
With the above configuration, the light emitting device of the present invention has excellent and stable optical characteristics such as luminance, light emission angle, and light intensity distribution, and has high performance and high reliability.
[0017]
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 an embodiment of the package of the present invention. Reference numeral 2 denotes a base, 4 denotes a first frame, and 6 denotes a second frame. A package 1 for housing is configured.
[0018]
The package of the present invention is joined to a base body 2 made of ceramics having a mounting portion 2a for mounting the light emitting element 5 at a center portion of the upper surface, and is mounted on the outer peripheral portion of the upper surface of the base 2 so as to surround the mounting portion 2a, with the inner surface facing outward. The first frame 4 includes a first frame 4 made of a metal inclined so as to expand toward the front, and a second frame 6 made of ceramics joined to an upper surface of the first frame 4.
[0019]
The base 2 in the present invention is a square flat plate made of ceramics such as aluminum oxide sintered body (alumina ceramics), aluminum nitride sintered body, mullite sintered body, glass ceramics, and the like. It functions as a support member for supporting, and has a mounting portion 2a for mounting the light emitting element 5 on its upper surface.
[0020]
The base 2 is covered with a wiring conductor 3 formed of a metallized layer extending from the mounting portion 2a and its periphery to the lower surface. The wiring conductor 3 is formed of a metallized layer of a metal powder such as W, Mo, Cu, and Ag, and functions as a conductive path for electrically connecting the light emitting element 5 housed inside the package 1 to the outside. A light emitting element 5 such as an LED or an LD is fixed to the mounting portion 2a with a conductive bonding material such as an Au-Si (silicon) alloy or an Ag-epoxy resin. The electrodes of the light emitting element 5 are electrically connected via bonding wires.
[0021]
Preferably, a metal having excellent corrosion resistance, such as Ni or Au, is applied to the exposed surface of the wiring conductor 3 to a thickness of about 1 to 20 μm to effectively prevent the wiring conductor 3 from being oxidized and corroded. And the connection between the wiring conductor 3 and the light emitting element 5 and the connection between the wiring conductor 3 and the bonding wire can be strengthened. Therefore, a Ni plating layer having a thickness of about 1 to 10 μm and an Au plating layer having a thickness of about 0.1 to 3 μm are sequentially deposited on the exposed surface of the wiring conductor 3 by electrolytic plating or electroless plating. Is more preferable.
[0022]
Further, the thermal conductivity of the base 2 is preferably 10 W / m · K or more, and when the thermal conductivity is 10 W / m · K or less, the surface temperature of the light emitting element 5 becomes 100 ° C. or more when a driving current of 50 mA or more is input to the light emitting element 5. , The life of the light emitting element 5 is not only deteriorated, but also the light output of the light emitting element 5 cannot be increased.
[0023]
The first frame 4 made of a metal is preferably made of silver (Ag), Al, Pt, or the like. These metals reflect light emitted from the light emitting element 5 to the outside of the package with a reflectance of 80% or more. Accordingly, a light-emitting device with high luminance can be manufactured. Further, the first frame 4 may be made of an Fe-Ni alloy, an Fe-Ni-Co alloy, or the like, and a metal layer having a high reflectivity such as Ag, Al, or Pt may be formed on the surface thereof.
[0024]
The first frame 4 is joined to the base 2 with a glass frit that melts at a melting point of 250 ° C. or higher, or with a resin adhesive such as a thermosetting epoxy resin or silicone resin. The first frame 4 has a through hole 4a having a circular or square cross section for accommodating the light emitting element 5 at the center thereof, and the light emitting element 5 is accommodated in the through hole 4a. And mounted on the mounting section 2a.
[0025]
The inner surface of the through hole 4a of the first frame 4 preferably has an arithmetic average roughness Ra of 0.004 to 4 μm, so that the inner surface of the first frame 4 The emitted light is favorably reflected. When Ra exceeds 4 μm, it becomes difficult to uniformly reflect the light emitted by the light emitting element 5 housed in the through hole 4a, and the intensity of the reflected light tends to be uneven. If the thickness is less than 0.004 μm, it tends to be difficult to form such a surface stably and efficiently.
[0026]
Further, 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 often sequentially applied to the inner surface of the through hole 4 a by an electrolytic plating method or an electroless plating method. In addition, the corrosion resistance of the first frame 4 is improved.
[0027]
The through-hole 4a preferably has a circular cross-sectional shape, and the light emitted by the light emitting element 5 housed in the through-hole 4a is uniformly reflected by the inner surface of the through-hole 4a so as to be extremely outward. Irradiation can be uniform.
[0028]
In the package 1 of the present invention, a second frame 6 made of ceramics is joined to the upper surface of the first frame 4, and the second frame 6 has, for example, substantially the same composition as the base 2. It is good to consist of ceramics. That is, the second frame 6 is preferably made of a material having the same thermal expansion coefficient as the base 2. In this case, the deformation of the first frame 4 can be suppressed due to the difference in thermal expansion coefficient between the base 2 made of ceramics and the first frame 4 made of metal, and the light emission angle and light intensity distribution can be reduced. It is possible to manufacture a light-emitting device having excellent and stable optical characteristics.
[0029]
Although the range of the spread angle (radiation angle) of the light varies depending on the use environment (temperature, etc.), the light emitting device is preferably suppressed to 10 degrees or less. In order to make the temperature equal to or less than 10 degrees, the difference in the thermal expansion coefficient between the base 2 and the second frame 6 is preferably 5 × 10 ⁻⁶ / ° C. or less. The light emission angle is constant at all cross sections if the cross section perpendicular to the optical axis of the light beam is circular, and the cross sectional shape at the cross section perpendicular to the optical axis of the light beam is elliptical. Is the maximum value if the shape is biased.
[0030]
The difference in the coefficient of thermal expansion between the base 2 and the second frame 6 and the first frame 4 is preferably 20 × 10 ⁻⁶ / ° C. or less, and if it exceeds 20 × 10 ⁻⁶ / ° C., the first Frame 4 is easily deformed.
[0031]
The second frame 6 is joined to the upper surface of the first frame 4 with a glass frit that melts at a melting point of 250 ° C. or higher, or a resin adhesive made of a thermosetting epoxy resin, silicone resin, or the like. Joined. The second frame 6 has a through-hole 6a having a circular or square cross-sectional shape for accommodating the light-emitting element 5 at a central portion thereof.
[0032]
The second frame 6 is preferably thicker than the base 2. That is, the bonding area between the first frame 4 and the base 2 is larger than the bonding area between the first frame 4 and the second frame 6, and the base 2 is larger than the second frame 6. Since the first frame 4 has a larger area, the first frame 4 is easily deformed under the influence of the thermal expansion of the base 2. Therefore, by making the thickness of the second frame 6 thicker than that of the base 2, the influence of thermal expansion on the upper and lower portions of the first frame 4 can be made the same, and the deformation of the first frame 4 can be improved. Can be further suppressed.
[0033]
Further, the second frame 6 may be provided with a metal layer having a high reflectivity such as Ag, Al, or Pt on its inner surface by plating or the like. In this case, the light of the light emitting element 5 can be efficiently reflected by the inner surface of the second frame 6 to provide a light emitting device with higher luminance.
[0034]
Thus, in the package 1 of the present invention, the light emitting element 5 is mounted on the mounting portion 2a of the base 2 and the electrodes of the light emitting element 5 are electrically connected to the wiring conductors 3 of the base 2 through the bonding wires. The light emitting device is obtained by installing a light transmitting member on the optical axis of the light emitting element 5 inside the first frame 4 or above the second frame 6. The translucent member may be a transparent resin such as a silicone resin covering the light emitting element 5, and may be a flat plate made of glass, sapphire, or the like, which is adhered to the upper surface of the second frame 6 with a resin adhesive or the like. It may be a lens-shaped translucent lid 7.
[0035]
It should be noted that the present invention is not limited to the above-described embodiment, and that various changes may be made without departing from the scope of the present invention.
[0036]
【The invention's effect】
The light-emitting element housing package of the present invention has a first frame body made of metal that is joined to the outer peripheral portion of the upper surface of the base body so as to surround the mounting portion conductive layer and that the inner surface is inclined so as to expand outward. Accordingly, light emitted from the light-emitting element can be reflected out of the light-emitting element housing package by 80% or more, so that a light-emitting device with high luminance can be manufactured. Further, since the second frame made of ceramics is provided, the first frame is prevented from being deformed due to a difference in thermal expansion coefficient between the base made of ceramics and the first frame made of metal. This makes it possible to manufacture a light-emitting device having excellent and stable optical characteristics such as light emission angle and light intensity distribution.
[0037]
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 conductive layer, and an optical axis of the light-emitting element inside the first frame or above the second frame. By having the translucent member installed on top, the optical characteristics such as brightness, light emission angle and light intensity distribution are excellent and stable, and high performance and high reliability Become.
[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: package for housing light emitting element 2: base 2a: mounting portion conductive layer 4: first frame 5: light emitting element 6: second frame 7: lid

Claims (2)

A base made of ceramics having a mounting portion conductor layer for mounting a light emitting element in the center of the upper surface, and joined to the outer peripheral portion of the upper surface of the base so as to surround the mounting portion conductor layer so that the inner surface expands outward. A light emitting element storage package, comprising: a first frame made of an inclined metal; and a second frame made of ceramics joined to an upper surface of the first frame. The light-emitting element storage package according to claim 1, a light-emitting element mounted on the mounting portion conductor layer, and an optical axis of the light-emitting element inside the first frame or above the second frame. A light-emitting device comprising: a light-transmitting member disposed on the light-emitting device.

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