JP4009208B2 - Light emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light emission 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 because they are expected to further reduce power consumption and extend their lifetime in the future. It has begun to be used in various fields such as various indicators, optical sensors, displays, photocouplers, backlights, and optical printer heads.
A cross-sectional view of a light emitting element storage package (hereinafter also referred to as a package) for mounting a conventional light emitting element is shown in FIG.
[0003]
As shown in FIG. 2, the conventional package 11 has a base body 12 made of a material such as various resins or ceramics. On the substrate 12, a metallized layer is formed by baking a conductor paste containing tungsten, molybdenum-manganese, or the like, and a wiring conductor 13 is formed on which a Ni plating layer or an Au plating layer is applied by plating. . Power is supplied from the outside to the light emitting element 15 in the package 11 through the wiring conductor 13.
[0004]
The base body 12 is provided with a substantially square frame body 14 made of various resins and ceramics having a through hole in the central portion on one main surface inside the package 11, and the frame body 14 is a base body. 12 is fixed by a brazing material such as silver (Ag) -copper (Cu) having a melting point of 700 to 900 ° C., a resin adhesive, or a low melting point glass that melts at 500 ° C. or less.
[0005]
The light emitting element 15 is die-bonded to the base 12 with an Ag paste 16. The electrode of the light emitting element 15 is wire-bonded by a wiring conductor 13 formed on the base 12 and a bonding wire 17 made of Au.
[0006]
Further, in order to protect the light emitting element 15, a transparent resin 18 is provided inside the frame body 14 so as to cover the light emitting element 15. This transparent resin 18 is formed by heat-curing a thermosetting epoxy resin or the like. The transparent resin 18 also has a function of firmly attaching the light emitting element 15 to the package 11. Thus, a light emitting device in which the light emitting element 15 is housed is obtained.
[0007]
This light-emitting device emits visible light by causing the light-emitting element 15 to emit light by a drive current supplied from an external electric circuit. Applications include various indicators, optical sensors, displays, photocouplers, backlights, and optical printer heads.
[0008]
In recent years, this light-emitting device has been used for illumination, and a device having higher characteristics in terms of high luminance and heat dissipation is required. In addition, when used for illumination, the lifetime is an important issue, and thus a long-life light emitting device is required.
[0009]
Therefore, recently, in order to improve the light emission luminance of the light emitting device, the frame body 14 and the base body 12 are often made of a material having a higher reflectance. For example, by using a highly reflective metal made of Ag or Al as the material of the frame body 14 that reflects the light of the light emitting element 15, or by attaching these metals to the inner peripheral surface of the frame body 14, It has been proposed to provide a light emitting device with brightness.
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-344029
[Problems to be solved by the invention]
However, the conventional package 11 has a problem in that the package 11 is distorted by heat emitted from the light emitting element 15, and as a result, the radiation angle of light emitted from the light emitting element 15 is not stabilized. This occurs due to the difference in thermal expansion coefficient between the base body 12 and the frame body 14 because the base body 12 is made of resin or ceramics while the frame body 14 is made of metal.
[0012]
Further, although the conventional package 11 can sufficiently cope with the increase in luminance, when the input power of the light emitting element 15 is increased in order to increase the luminance, the light intensity stabilized by the heat emitted from the light emitting element 15 and the light emission angle are increased. A new problem has arisen that the light intensity distribution cannot be obtained. When the heat dissipation is deteriorated, the temperature of the light emitting element 15 is increased, and the heat history of the temperature increase and the temperature decrease is repeated, whereby the strength of the light emitting element 15 itself is decreased. Further, the light emitting element 15 and the package 11 are distorted, and the light emission angle and light intensity distribution measured at a certain distance from the package 11 deviate from desired values and patterns. The light intensity distribution is represented by a single light beam (light beam) or an aggregate thereof, and the pattern of the light beam becomes unstable due to distortion of the package 11 and becomes unstable. As described above, when the light-emitting device is used for local illumination or the like, the light emission angle and the light intensity distribution are important problems.
[0013]
Therefore, the present invention has been completed in view of such conventional problems, and the object thereof is to satisfactorily reflect the light emitted from the light emitting element on the inner peripheral surface of the frame body and to radiate it uniformly and efficiently to the outside. A further object is to provide a light-emitting element storage package and a light-emitting device capable of producing a light-emitting device capable of obtaining stable optical characteristics in which light intensity, light emission angle, and light intensity distribution do not change due to temperature change.
[0014]
[Means for Solving the Problems]
The light-emitting device of the present invention is made of a metal material and has a base having a protrusion, and an insulating material, and has an upper surface and a lower surface bonded to the base, and the protrusion of the base is disposed. A first frame body having a void, a first derivation portion provided on the upper surface of the first frame body, and a second derivation portion provided on the lower surface of the first frame body. And electrically connected to the wiring conductor formed in the first frame located on the joint between the base and the first frame, and to the first lead-out portion of the wiring conductor. A light emitting element mounted on the projecting portion of the base, and an external lead terminal provided on the lower surface of the first frame body, electrically connected to the second lead-out portion of the wiring conductor. The first frame body that covers the light emitting element and is provided with the first lead-out portion of the wiring conductor. Metal having a resin deposited on the upper surface and an inner peripheral surface inclined so as to spread upward, and attached to the upper surface of the first frame so as to surround the light emitting element The 2nd frame which consists of.
[0015]
The light-emitting device of the present invention has an inner peripheral surface surrounding the light-emitting element, and has a second frame disposed on the upper surface of the first frame .
[0016]
In addition, the light emitting device of the present invention includes a transparent resin that covers the light emitting element .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The light emitting device of the present invention will be described in detail below. FIG. 1 is a cross-sectional view showing an embodiment of a light emitting element storage package used in a light emitting device of the present invention. In FIG. 1, 2 is a base, 3 is a first frame, and 4 is a second frame. Thus, the package 1 for accommodating the light emitting element 5 is mainly constituted by these.
[0018]
The light-emitting element storage package used in the light- emitting device of the present invention includes a base 2 made of metal having a mounting portion 2a on which the light-emitting element 5 is mounted at the center of the upper main surface, and an outer peripheral portion of the upper main surface of the base 2 A first frame body formed of a frame-like insulator having an outer dimension larger than that of the base body 2 and being led out from the vicinity of the mounting section 2a to the outside is attached so as to surround the mounting section 2a. 3 and a second frame 4 made of a metal attached to the upper surface of the first frame 3 so as to surround the mounting portion 2a and having an inner peripheral surface that is an inclined surface extending upward. Yes.
[0019]
The substrate 2 of the present invention functions as a support member for supporting and mounting the light emitting element 5 and a heat dissipation member for dissipating the heat of the light emitting element 5. A mounting portion 2 a for mounting the light emitting element 5 is provided at the center of the upper surface of the base 2. The light emitting element 5 is attached to the mounting portion 2a via a low melting point brazing material such as a resin adhesive or tin (Sn) -lead (Pb) solder. And the heat | fever of the light emitting element 5 maintains favorable the operativity of the light emitting element 5 by being transmitted to the base | substrate 2 via a resin adhesive and a low melting-point brazing material, and being efficiently dissipated outside. Further, the light emitted from the light emitting element 5 is reflected on the inner peripheral surface of the second frame body 4, a lens installed on the optical axis of the light emitting element 5 inside or above the second frame body 4, and the like. And is converted into diffused light, parallel light, or the like and emitted to the outside.
[0020]
The substrate 2 is made of a metal such as an iron (Fe) -nickel (Ni) -cobalt (Co) alloy or a copper (Cu) -tungsten (W) alloy, and the ingot is conventionally known such as rolling or punching. It is formed and formed into a predetermined shape by performing metal processing. In particular, in order to enhance the heat dissipation effect, the substrate 2 is preferably made of a Cu—W alloy having excellent thermal conductivity. In addition, the surface is plated with a metal having excellent corrosion resistance and wettability with the brazing material, specifically, a Ni layer having a thickness of 0.5 to 9 μm and a gold (Au) layer having a thickness of 0.5 to 9 μm. The substrate 2 is preferably deposited sequentially by a method, and the base 2 can be effectively prevented from being oxidatively corroded, and the light emitting element 5 can be firmly bonded to the mounting portion 2a on the upper surface of the base 2.
[0021]
The base body 2 has a first frame 3 made of an insulator joined to an outer peripheral portion of an upper surface thereof so as to surround the mounting portion 2 a, and is for accommodating the light emitting element 5 inside the first frame 3. A void is formed. The first frame 3 has an outer dimension larger than that of the base 2 and a wiring conductor 3a that is led out from the vicinity of the mounting portion 2a to the outside. The first frame 3 is made of an insulator such as an aluminum oxide sintered body (alumina ceramic), an aluminum nitride sintered body, a glass ceramic, or a resin.
[0022]
Further, the wiring conductor 3a formed on the first frame 3 is formed of a metallized layer such as tungsten (W), molybdenum (Mo), manganese (Mn), copper (Cu), etc. A metal paste obtained by adding and mixing an organic solvent and a solvent is printed and applied in a predetermined pattern and baked to form the first frame 3. In order to prevent the oxidation and to firmly connect the bonding wire 7 and the external lead terminal 8 to the surface of the wiring conductor 3a, a Ni layer having a thickness of 0.5 to 9 μm and an Au layer having a thickness of 0.5 to 5 μm A metal layer such as a layer may be deposited by a plating method.
[0023]
In the present invention, as shown in FIG. 1, the external lead terminal 8 is inserted into the space formed in the outer peripheral portion of the lower surface of the first frame 3 and is electrically connected to the wiring conductor 3 a of the first frame 3. Therefore, the external lead terminal 8 is not bulky and has a low profile.
[0024]
The second frame 4 of the present invention is made of Al (aluminum), Ag, Fe—Ni—Co alloy, Fe—Ni alloy, or the like, and particularly made of Al having a high reflectance in order to enhance the light reflection effect. Is preferred. The second frame 4 has a shape in which the inner peripheral surface is an inclined surface that expands upward. The ingot made of the material is subjected to conventionally known metal processing such as cutting, rolling, and punching. As a result, the predetermined shape is formed.
[0025]
Further, the inner peripheral surface of the through hole 4 a of the second frame 4 is formed so as to expand upward at an angle of 35 to 60 degrees with respect to the upper surface of the base 2. Thus, the light of the light emitting element 5 accommodated in the through hole 4a is favorably reflected on the inner peripheral surface of the inclined through hole 4a, and the light is radiated to the outside within a range of an emission angle of 20 degrees or less. The light emission efficiency of the light emitting device using the package 1 of the present invention can be made extremely high.
[0026]
The light emission angle is as seen in a longitudinal section as shown in FIG. 1, and if the cross-sectional shape in a cross section perpendicular to the optical axis of the light beam is circular, the radiation angle is constant, and the light beam If the cross section of the cross section perpendicular to the optical axis has a deviation such as an elliptical shape, the radiation angle is the maximum value.
[0027]
When the angle formed by the inner peripheral surface of the through hole 4a of the second frame 4 with the upper surface of the base body 2 is less than 35 degrees, the radiation angle spreads to 20 degrees or more, the amount of dispersed light increases, and the luminance of light increases. descend. On the other hand, when the angle exceeds 60 degrees, the amount of light diffusely reflected in the package 1 without being emitted well outside the package 1 increases. Therefore, the angle between the inner peripheral surface of the through hole 4a of the second frame 4 and the upper surface of the base 2 is preferably 35 to 60 degrees.
[0028]
If the arithmetic average roughness Ra of the inner peripheral surface of the through hole 4a of the frame 4 exceeds 4 μm, it becomes difficult to uniformly reflect the light emitted from the light emitting element 5 accommodated in the through hole 4a. The intensity of the reflected light tends to be biased. On the other hand, when the intensity is less than 0.004 μm, it tends to be difficult to form such a surface stably and efficiently. Therefore, the arithmetic average roughness Ra of the inner peripheral surface of the through hole 4a is preferably 0.004 to 4 μm.
[0029]
In addition, in order to make Ra of the internal peripheral surface of the through-hole 4a into said range, it can process by a conventionally well-known chemical etching method or a cutting method. Alternatively, a transfer processing method using the surface accuracy of the mold may be used.
[0030]
In the present invention, the base body 2, the first frame body 3 and the second frame body 4 are joined with a resin adhesive such as silicone or epoxy, or a metal brazing material such as Ag-Cu brazing or Pb- This is performed by solder such as Sn, Au-Sn, Au-Si. The bonding material for bonding the base body 2, the first frame body 3 and the second frame body 4 may be appropriately selected in consideration of the material, thermal expansion coefficient, etc. of the base body 2, the first frame body 3 and the second frame body 4. Although not particularly limited, a metal brazing material or solder is preferable when high reliability of bonding is required.
[0031]
In the light emitting element storage package of the present invention, the base 2, the first frame 3, and the second frame 4 have similar or the same thermal expansion coefficients of the base 2 and the first frame 3. It is preferable that the thermal expansion coefficients of the base body 2, the first frame body 3, and the second frame body 4 are similar or the same. Thereby, the distortion of the package 1 due to the temperature change can be eliminated or suppressed.
[0032]
For example, the heat of the base 2 made of Fe—Ni—Co alloy (thermal expansion coefficient 6 × 10 −6 / ° C.) or the like and the second frame 4 made of Al (thermal expansion coefficient 23 × 10 −6 / ° C.) or the like. Even if the expansion coefficients are different, the distortion caused thereby can be reduced. That is, even if distortion occurs due to the influence of the second frame body 4, the first frame body 3 made of alumina ceramic (thermal expansion coefficient 5.7 × 10−6 / ° C.) or the like and the base body 2 absorb the distortion. And distortion of the entire package 1 can be reduced.
[0033]
In order to stabilize the light emitted from the light-emitting element 5 so as not to change by suppressing the spread of light, it is preferable to suppress the change in the light emission angle due to a temperature change or the like to 10 degrees or less. If the difference in thermal expansion coefficient between the base 2 and the first frame 3 is 5 × 10 −6 / ° C. or less, the change in the light emission angle can be suppressed to 10 degrees or less. Therefore, the difference in thermal expansion coefficient between the base 2 and the first frame 3 is preferably 5 × 10 −6 / ° C. or less.
[0034]
Moreover, it is preferable that the outer peripheral end of the base body 2 overlaps with the inner peripheral end of the lower surface of the second frame body 4 in the vertical direction. Thereby, in the 1st frame 3, the site | part with a small intensity | strength which does not overlap between the outer peripheral end of the base | substrate 2 and the inner peripheral end of the lower surface of the 2nd frame 4 does not generate | occur | produce, It is possible to suppress cracking or breakage due to a difference in thermal expansion coefficient between the base 2 and the second frame 4.
[0035]
In the present invention, a step 4b is formed between the upper surface and the inner peripheral surface of the second frame body 4, and an end of a translucent member such as a lens is locked and attached to the step 4b. In this case, the optically coupled state between the light emitting element 5 and the translucent member can be stably maintained, and a light emitting device with stabilized optical characteristics can be obtained.
[0036]
The thermal conductivity of the substrate 2 is preferably 100 W / m · K or more. Thereby, the heat dissipation of the light emitting element 5 can be improved and the drive current value which can be input into the light emitting element 5 can be increased. If it is less than 100 W / m · K, for example, if the drive current value is 20 mA, the chip junction temperature, which is the heat of the light-emitting element 5, will be 65 ° C. or more, the thermal load applied to the light-emitting element 5 will increase, and 10,000 hours will be required. It becomes difficult to ensure a longer life. At 100 W / m · K or higher, the junction temperature of the light-emitting element 5 is 50 ° C. or lower even when the drive current value is 20 mA, and a lifetime exceeding 10,000 hours can be secured, and a larger drive current is input. The light output of the light emitting element 5 can be improved.
[0037]
Note that the chip junction temperature is the temperature of the chip (light emitting element 5) when a predetermined drive current (20 mA or the like) is input, and is preferably as low as possible. That is, if the heat dissipation property is not increased, heat is accumulated in the light emitting element 5 and the chip junction temperature does not decrease. Therefore, if the heat dissipation property is increased and the chip junction temperature is decreased, a current can flow.
In general, it is said that when the temperature is 65 ° C. or higher, the limit of the light-emitting element 5 is exceeded, and no further drive current can be input.
[0038]
Thus, by mounting the light emitting element 5 on the mounting portion 2a of the base body 2, and electrically connects the electrode of the light emitting element 5 and the wiring conductor 3a through a bonding wire 7, and thereafter, the light-emitting element 5 at a transparent resin Covering or filling the through hole 4a in which the light emitting element 5 is accommodated with a transparent resin to seal the light emitting element 5, and installing a translucent member on the step 4b on the upper surface of the second frame 4. It becomes a light emitting device.
[0039]
【The invention's effect】
The light emitting device of the present invention includes a base made of a metal material and having a protruding portion, an insulating material, an upper surface and a lower surface joined to the base, and a cavity in which the protruding portion of the base is disposed. A first frame body, a first derivation portion provided on the upper surface of the first frame body, and a second derivation portion provided on the lower surface of the first frame body. A wiring conductor formed inside the first frame located on the joint with the body and an external connection provided on the lower surface of the first frame, electrically connected to the second lead-out portion of the wiring conductor since has a lead terminal, the excellent light emission efficiency and heat dissipation, Ru stable optical characteristics can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an embodiment of a light-emitting element storage package used in a light- emitting device of the present invention.
FIG. 2 is a cross-sectional view of a conventional light emitting element storage package.
[Explanation of symbols]
1: Light-emitting element storage package 2: Base 2a: Mounting portion 3: First frame 3a: Wiring conductor 4: Second frame 5: Light-emitting element

Claims (2)

A base made of a metal material and having a protruding portion;
A first frame body made of an insulating material, having an upper surface and a lower surface bonded to the base body, and having a space where the projecting portion of the base body is disposed;
A first derivation portion provided on the upper surface of the first frame body; and a second derivation portion provided on the lower surface of the first frame body, the base body, the first frame body, A wiring conductor formed inside the first frame located on the joint of
A light emitting element electrically connected to the first lead-out portion of the wiring conductor and mounted on the protruding portion of the base;
An external lead terminal electrically connected to the second lead-out portion of the wiring conductor, provided on the lower surface of the first frame,
A resin that covers the light emitting element and is partially adhered to the upper surface of the first frame body provided with the first lead-out portion of the wiring conductor ;
A second frame made of metal having an inner peripheral surface inclined so as to spread upward and attached to the upper surface of the first frame so as to surround the light emitting element; A light emitting device characterized by comprising: Claim 1 Symbol placement of the light emitting device characterized by having a transparent resin covering the light emitting element.

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