JP4165592B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device used for various light sources such as a backlight light source, a display, and an illumination, and an optical sensor, and particularly relates to a light emitting device having excellent reliability.

  Today, high-luminance and high-power semiconductor light-emitting elements and small and highly sensitive light-emitting devices have been developed and used in various fields. Such a light-emitting device is utilized for, for example, a light source of an optical printer head, a light source of a liquid crystal backlight, a light source of various meters, various reading sensors, and the like, taking advantage of features such as low power consumption, small size, and light weight.

An example of such a light emitting device is a light emitting device as shown in FIG.
Using a plastic package 5 having a recess and integrally formed with the lead electrode 2 inserted, the LED chip 1 is die-bonded as a light emitting element on the lead electrode 2 exposed from the bottom surface of the recess, and each LED chip The electrode and the lead electrode 2 provided in the package are electrically connected by a gold wire 4 or the like. In this way, the LED chip disposed in the recess is sealed with a translucent mold resin 9 or the like. As a result, the LED chip, the wire and the like disposed inside the package can be protected from the external environment such as moisture and external force, and a light emitting device having extremely high reliability can be obtained.

However, such light-emitting devices have begun to be used under more severe environmental conditions due to the expansion of application fields. In a light emitting device used for an aircraft or a vehicle, for example, the temperature may change to −20 ° C. or lower and + 80 ° C. or higher depending on the outside temperature. There is also vibration at the same time as external pressure, thermal shock, and the like. In such a case, the LED chip is peeled off from the die bond resin due to expansion or contraction of the mold resin or the like, and the intensity or directivity of the emitted light changes. In severe cases, wire breakage may occur and no light may be emitted.
The light emitting element generates heat due to power consumption. The light emitting device having the above configuration can release heat generated from the light emitting element to the substrate side through the lead electrode.

  However, the heat dissipation effect is not fully satisfactory, and when a large current is applied to the light emitting device as described above in order to improve the output of the light emitting element, the temperature of the light emitting element rises because the heat dissipation effect by the package is not sufficient. As a result, the operating speed of the element and the deterioration of the resin existing in the surrounding area are caused.

On the other hand, a can-type package is conventionally used as a highly reliable package.
For example, as shown in FIG. 12, a convex metal base 10 and a lead electrode hermetically insulated and sealed through an insulator 3 such as glass in a through hole formed in the thickness direction of the metal base 10. 2 is used. The light emitting element 1 is electrically connected to the upper surface of such a stem. This is hermetically sealed with a can 11 with a window having a flange on the bottom side.

The light emitting device configured as described above has a very high reliability compared to the case where resin is used as a constituent material because the package is made of metal and the inside is hollow, and prevents wire breakage and moisture resistance. Excellent heat resistance and heat dissipation. For this reason, it is possible to increase the amount of current flowing through the light emitting device and improve the output.
Japanese Utility Model Publication No. 4-25257 JP 2000-58924 A JP 2000-252524 A

  However, in recent years, it has been desired to reduce the size and thickness of light-emitting devices in order to support high-density mounting, and accordingly, surface-mounted light-emitting devices are required instead of lead-type light-emitting devices.

  An object of the present invention is to provide a thin surface-mounted light-emitting device that has high reliability and can emit light with high luminance.

Therefore, the present invention comprises a light emitting element, a metal package comprising a recess housing the light emitting element and a base part having at least one through hole, a translucent window part and a metal part, A light emitting device having a lid that seals the recess, and a lead electrode that is electrically separated from the metal package by an insulating member and that is inserted into the through-hole so that a tip portion protrudes from the bottom surface of the base portion The surface of the recess that is the outer surface facing the surface on which the light emitting element is mounted is exposed at the bottom surface of the metal constituting the metal package, and the bottom surface of the recess and the lead from which the metal surface is exposed. and the bottom surface of the electrode is positioned on the same plane, the window portion have a fluorescent substance, in the metal package, the recess bottom surface of a side wall of the concave portion is from recess bottom surface portion Kuna' wherein the are. As a result, a light-emitting device with good mountability and high reliability can be obtained.

Furthermore, it is preferable that the upper surface side of the lead electrode protrudes from the main surface of the base portion because the accuracy of wire bonding is improved.
The base portion may be thicker than the bottom surface of the recess.
Thereby, high heat dissipation and strong strength can be shared, and a light emitting device with excellent yield can be obtained.
Moreover, it is preferable that the inner wall of the said recessed part is a taper shape, and, thereby, the light extraction efficiency from a light emitting element is improved further.

Also, when the pre KiToruhikari properties window to intersect an extension of the inner wall of the recess opposite to have and the recess may light reflected scattered by the inner wall of the emitted said recess from the light emitting device efficiency outside Can be taken out.

The metal package has a thermal conductivity of 10 W / m · K to 100 W / m · K and a thermal expansion coefficient of 0.05 × 10 ⁻⁴ / deg to 0.20 × 10 ⁻⁴ / deg. If it exists , the light-emitting device which can drop a large electric current without impairing reliability is obtained.

Further, the recess, when has an edge projecting from the base portion adjacent, by effectively utilizing the principal surface area of the package, it is possible to increase the extraction efficiency further light.
Further, the translucent window portion includes a bending point that is a rising point of the inner wall of the recess facing one side surface of the light emitting element, and an uppermost end point of the inner wall of the recess facing the bending point through the light emitting element. When the intersect with the extension line of a straight line connecting, can also light reflected scattered greatly diverted by the inner wall taken to the outside from the translucent window portion.

  According to the present invention, it is possible to provide a thin surface-mounted light-emitting device that has high reliability and can emit light with high luminance.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 5 shows a light emitting device according to an embodiment of the present invention.
The package 5 is made of metal, and has a recess a for accommodating the light emitting element in the center. Moreover, the base part b which is a peripheral part of the said recessed part has two through-holes penetrated in the thickness direction, and each through-hole has opposed the said recessed part on both sides. Positive and negative lead electrodes 2 are inserted into the through-holes through hard glass which is an insulating member 3.
Both end portions of the lead electrode 2 protrude from the surface of the base portion, and the bottom surface of the lead electrode is located substantially on the same plane as the bottom surface of the recess. In this specification, the surface of each member in the recess opening direction of the package is defined as a main surface, and the surface opposite to the main surface is expressed as a back surface or a bottom surface.

  On the main surface side of the metal package configured as described above, the LED chip which is the light emitting element 1 is arranged in the recess, and each electrode of the LED chip is electrically connected to each lead electrode 2 by the wire 4. . The main surface side of the package thus made conductive is hermetically sealed with a lid 6 having a translucent window portion 7.

  Here, the translucent window portion 7 can contain various fluorescent materials 8 such as an inorganic fluorescent material and an organic fluorescent material. As an example of such a fluorescent substance 8, there is a phosphor containing a rare earth element which is an inorganic phosphor. As the rare earth element-containing phosphor, specifically, at least one element selected from the group of Y, Lu, Sc, La, Gd, and Sm, and at least one selected from the group of Al, Ga, and In And a garnet-type phosphor having an element. In particular, yttrium-aluminum oxide phosphors activated with cerium are preferable, and in addition to Ce, Tb, Cu, Ag, Au, Fe, Cr, Nd, Dy, Ni, Ti, Eu, and Pr may be used as desired. Etc. can also be contained. Here, the fluorescent material 8 that can absorb at least a part of the light from the LED chip and emit different wavelengths is contained. As described above, a light-emitting device that is composed of only an inorganic material without using an organic material as a packaging material or a binder of a fluorescent material can avoid deterioration of the structural member due to heat or light, and has extremely high reliability. Can have sex.

Hereafter, each structure in embodiment of this invention is explained in full detail.
<Light emitting element 1>
In the present invention, the light-emitting element 1 is not particularly limited. However, when a fluorescent material is used, a semiconductor light-emitting element having a light-emitting layer capable of emitting an emission wavelength capable of exciting the fluorescent material is preferable. Can be mentioned various semiconductors such as ZnSe or GaN as such semiconductor light emitting device, a short wavelength capable of emitting nitride semiconductor capable of efficiently exciting the fluorescent substance _{(In X Al Y Ga 1-} X-Y N, Preferred examples include 0 ≦ X, 0 ≦ Y, and X + Y ≦ 1). If desired, the nitride semiconductor may contain boron or phosphorus. Examples of the semiconductor structure include a homostructure having a MIS junction, a PIN junction, and a pn junction, a heterostructure, and a double heterostructure. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal. In addition, a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed in a thin film in which a quantum effect is generated can be used.

  When a nitride semiconductor is used, materials such as sapphire, spinel, SiC, Si, ZnO, and GaN are preferably used for the semiconductor substrate. In order to form a nitride semiconductor with good crystallinity with high productivity, it is preferable to use a sapphire substrate. A nitride semiconductor can be formed on the sapphire substrate by MOCVD or the like. A buffer layer made of GaN, AlN, GaAIN or the like is formed on the sapphire substrate, and a nitride semiconductor having a pn junction is formed thereon.

  As an example of a light emitting device having a pn junction using a nitride semiconductor, a first contact layer formed of n-type gallium nitride, a first cladding layer formed of n-type aluminum nitride / gallium, and a nitride layer on a buffer layer Examples include a double hetero structure in which an active layer formed of indium gallium, a second cladding layer formed of p-type aluminum nitride / gallium, and a second contact layer formed of p-type gallium nitride are sequentially stacked.

  Nitride semiconductors exhibit n-type conductivity without being doped with impurities. When forming a desired n-type nitride semiconductor, for example, to improve luminous efficiency, it is preferable to appropriately introduce Si, Ge, Se, Te, C, etc. as an n-type dopant. On the other hand, when forming a p-type nitride semiconductor, the p-type dopants such as Zn, Mg, Be, Ca, Sr, and Ba are doped. Since nitride semiconductors are not easily converted to p-type by simply doping with a p-type dopant, it is preferable to reduce resistance by heating in a furnace or plasma irradiation after introducing the p-type dopant. After the electrodes are formed, a light emitting element made of a nitride semiconductor can be formed by cutting the semiconductor wafer into chips.

  In the light emitting diode of the present invention, in order to emit white light, the emission wavelength of the light emitting element is preferably 400 nm or more and 530 nm or less in consideration of the complementary color relationship with the emission wavelength from the fluorescent material, deterioration of the translucent resin, and the like. 420 nm or more and 490 nm or less is more preferable. In order to further improve the excitation and emission efficiency of the light emitting element and the fluorescent material, 450 nm or more and 475 nm or less are more preferable.

  In the present invention, since the package body is made of only metal, it is possible to suppress deterioration of the constituent members due to ultraviolet rays. Accordingly, the light emitting device of the present invention uses a light emitting element having a main emission wavelength in the near ultraviolet or ultraviolet region, and a fluorescent material capable of absorbing a part of light from the light emitting element and emitting other wavelengths. By combining these, a color conversion light emitting device with little color unevenness can be obtained. Here, when the fluorescent substance is bound to a light emitting device, it is preferable to use a resin that is relatively resistant to ultraviolet rays, glass that is an inorganic substance, or the like.

<Metal package 5>
The metal package 5 used in the light emitting device of the present embodiment includes a concave portion a that houses a light emitting element, and a base portion b on which lead electrodes are arranged. The bottom surface of the recess and the bottom surface of the lead electrode are substantially on the same plane.

In the light-emitting device, it is preferable that the metal package be formed thin in consideration of heat dissipation of heat generated from the light-emitting element and downsizing of the package. On the other hand, in order to alleviate the difference in coefficient of thermal expansion between the metal of the package material and the insulating member adjacent to the metal and improve the reliability, it is necessary to enlarge each contact surface. Is preferably formed. In view of this, the present inventor separated the portion where the light emitting element is arranged and the portion where the lead electrode is fixed in the metal package, and by setting the shape and thickness according to the purpose in each region, the reliability is improved. Improve.
Hereinafter, each component will be described in detail.

<Recess a>
The package used in the light-emitting device of this embodiment has a concave portion in the central portion that can accommodate the light-emitting element and can efficiently dissipate heat generated from the light-emitting element. The bottom surface of the recess is located substantially on the same plane as the mounting surface of the light emitting device, that is, the bottom surface of the lead electrode, and is configured to contact the surface of the mounting substrate 27. By configuring in this way, a high thermal conductivity region 28 is provided separately from the wiring 29 on the surface of the mounting substrate 27, and the high thermal conductivity region 28 and the concave bottom surface are fixed by a conductive member, Heat generated from the light emitting element can be directly radiated to the mounting substrate, and the amount of current dropped on the light emitting element can be increased to improve output. Moreover, when providing the support body which has electroconductivity in the back surface of a metal package, it is preferable that the said support body adheres with the said high heat conductive area | region 28 and a conductive member similarly to the said recessed part bottom face.

  Moreover, the film thickness of the bottom face of the recess is formed thinner than the base part corresponding to the outer peripheral part so as to have good heat dissipation. Thereby, a thermal resistance difference can be provided in the thin part and the thick part which is the base part, and heat can be efficiently radiated from the thin part. The thickness of the thin wall portion that is the bottom surface of the recess is preferably 0.05 mm to 0.2 mm, more preferably 0.05 mm to 0.1 mm. The bottom surface of the recess set in this way is preferable because of its low thermal resistance. As described above, the light emitting device of the present invention can directly radiate the heat generated from the light emitting element to the mounting substrate through a heat radiation path shorter than the region where the thermal resistance is set to be low from the outside, thereby realizing low thermal resistance. ing. The thin-walled main surface that is the bottom surface of the concave portion is substantially parallel to the main-surface of the thick-walled portion that is the base portion, and the inner walls of the concave portions that are the main surface of these boundary portions are bent. Thereby, the thermal resistance difference of the said thin part and the said thick part becomes large, and can further improve heat dissipation.

The concave portion is preferably located in the central portion of the light emitting device, whereby good directivity characteristics can be obtained.
Moreover, it is preferable that a recessed part has a volume which can accommodate the said light emitting element whole. Thereby, the light emitted from the four side surfaces of the light emitting element can be favorably extracted in the front direction through the inner wall of the recess. Thereby, it is possible to improve unevenness in light emission and color unevenness particularly seen in a light emitting device made of a nitride semiconductor, which is preferable. In addition, when the wavelength of the light emitting element is converted using the color conversion layer, the entire light emitting element arranged in the concave portion can be easily covered with the color conversion layer. In addition, it is preferable to provide a translucent member that covers the light-emitting element in the concave portion because light extraction efficiency is improved. In the present embodiment, the light-emitting member emits the light in the color conversion layer containing a fluorescent material capable of absorbing a part of the light emitted from the light-emitting element and emitting other wavelengths. The element is covered. Since the metal package used in the present invention is particularly excellent in heat dissipation of the concave portion in which the light emitting element is disposed, each member of the color conversion layer is not limited to an inorganic material, and an organic material can be used. The organic matter hardly deteriorates due to the above, and good optical characteristics can be obtained. Moreover, it is preferable that the inner wall of the said recessed part is a taper shape so that a volume may become so large that it goes to the opening side, and, thereby, the light-emitting device which can light-emit with higher brightness | luminance is obtained.

  On the other hand, the back surface of the concave portion on the outer wall side has an inverted convex shape, and preferably has a groove between the bottom surface of the concave portion and the bottom surface of the lead electrode. It is possible to prevent a short circuit between the electrodes, and it is possible to mount the semiconductor device with high reliability and good quality. If there is no groove, the solder attached to the bottom surface of the lead may adhere to the adjacent base portion and the like, and insulation between the electrodes may not be taken, resulting in a short circuit.

  The concave portion is formed by, for example, drawing a metal flat plate. In the present embodiment, the metal plate is drawn from the main surface direction of the metal flat plate to flow the metal in the back surface direction to form the recess. By configuring the flowing metal to be a part of the bottom surface of the recess, the area of the mounting surface can be increased, and the film thickness on the bottom surface side of the side surface of the recess can be increased. Specifically, the film thickness of the concave portion constituting the mounting surface is such that the light emitting element mounting portion whose main surface side is flat is thin, and the outer peripheral portion of the light emitting element mounting portion whose main surface side is a part of the side wall of the concave portion Is constructed thick. This is preferable because heat dissipation is improved and the mechanical strength of the package is increased. Further, it becomes possible to mount with high accuracy, and preferable directivity characteristics can be obtained.

<Base part b>
In this specification, a flat plate portion surrounding the recess a in the metal package is defined as a base portion b. The base portion has at least one through hole penetrating in the thickness direction. The through hole is for fixing the lead electrode, and the light emitting device of the present embodiment has the two through holes. The respective through holes are provided to face each other with the recess a interposed therebetween, and positive or negative lead electrodes are inserted into the respective interiors via insulators. With this configuration, the light emitting element can be disposed at the center between the lead electrodes, and good directivity can be obtained.

  Here, at least one of the positive and negative lead electrodes of the light emitting device of the present invention may be inserted through an insulator in the through hole of the base portion, and the other lead electrode is a metal package as shown in FIG. And may be integrally formed. When configured in this way, since it is composed of a continuous material without an insulator from the light emitting element arrangement surface of the package recess that is a heat generation source to the other lead electrode, heat is well dispersed, Heat can be radiated well from the bottom surface of the recess, the bottom surface of the other lead electrode, and the back surface between them.

  In the light emitting device of the present invention, the thickness of the base portion of the metal package is larger than the thickness of the bottom surface of the recess. The thickness of the base part is preferably 0.3 mm to 1.0 mm, more preferably 0.5 mm to 1.0 mm. When it is thinner than 0.3 mm, the strength of the entire package is lowered. In addition, cracks may occur at the weld interface due to stress strain that occurs during welding with the lid, and if airtightness is incomplete in this way, moisture will enter the interior and the wires and light emitting elements will be corroded, reducing reliability. End up. On the other hand, when the film thickness is 1.0 mm or more, it is difficult for a pulse current to be transmitted to the welding interface, which may result in incomplete sealing. Further, the cost of the light emitting device increases as the thickness of the light emitting device increases.

  Moreover, it is preferable that the outer edge part of the said base part has a collar part along the base part bottom face. By configuring in this way, the package end surface exposed by providing the flange portion and the inner wall of the lid disposed on the light emitting surface side, and the upper surface of the flange portion and the upper surface of the lid are combined, and positioning thereof is performed. This is preferable because it can be easily carried out and the mass productivity is improved.

  Moreover, you may provide a support body in the back side of the said base part. It is preferable that the support members are arranged at equal intervals between the lead electrodes protruding from the back side, because the mounting stability of the light emitting device is improved. The support is preferably made of the same material as that of the base portion, thereby improving the heat dissipation of the light emitting device. Such a support can be easily formed by, for example, pressing from the main surface side of the base portion and flowing a part of the metal to the back surface side.

The thermal conductivity of the lead electrode and the metal package is preferably in the range of 10 W / m · K to 100 W / m · K, more preferably 15 W / m · K to 80 W / m · K, Preferably, it is 15 W / m · K or more and 50 W / m · K or less. Thus, a light emitting device capable of supplying a large current for a long time while maintaining reliability can be obtained.
Each coefficient of thermal expansion is preferably in the range of 0.05 × 10 ⁻⁴ / deg to 0.20 × 10 ⁻⁴ / deg.

The thermal expansion coefficient of the metal package is preferably a value that is the same as or larger than the thermal expansion coefficient of the insulating member. In the former case, the members can be brought into thermal contact with each other without being damaged. In the latter case, if the difference in thermal expansion coefficient is 0.01 × 10 ⁻⁴ / deg or less, the contact area is increased as much as possible to avoid breakage due to the difference in thermal expansion coefficient. The metal package is moderately shrunk in the inner direction of the through hole due to the effect of the difference in thermal expansion coefficient, and the metal package and the insulating member are brought into close contact with each other without providing a base oxide film on the inner wall of the through hole. be able to. Thereby, the work process is simplified, and a light emission measure with good productivity is obtained.

Moreover, it is preferable that the base material of a metal package has strong intensity | strength, and can thereby form a thin package with high reliability. Examples of a preferable base material for the metal package include kovar and iron. Kovar is an Fe—Ni—Co alloy and has a thermal expansion coefficient close to that of low-melting glass used for an insulating member, and thus can be hermetically sealed. It is preferable to perform Ag plating on the outermost surface of these base materials. This configuration is preferable because the light reflection / scattering rate on the package surface is improved and the Ag layer becomes a brazing filler metal, and the adhesion between the light emitting element, the wire and the lid, and the metal package body is improved. Further, when the main surface side of the package irradiated with light from the light emitting element is plated with an Ag layer glossy, and only the portion of the Ag layer that is desired to improve adhesion to other members is plated with a matte surface, these effects are obtained. Is propagated.
The metal package used in the present invention is configured as described above, whereby a highly reliable light emitting device can be obtained at low cost.

<Lead electrode>
The light-emitting device of the present invention has positive and negative lead electrodes, and at least one of them is integrally provided via a base portion of a metal package and an insulating member. For example, a through hole is provided in the base portion and inserted into the through hole via an insulating member. The leading end portion of the lead electrode protrudes from the surface of the base portion, and the bottom surface of the lead electrode is located on substantially the same plane as the mounting surface side bottom surface of the recess.

Top a wire connection surface of the lead electrode 2 ^preferably has a surface area in the range of 0.02 mm 2 ～0.2Mm ^2, more preferably 0.05mm ² ~0.15mm ^2. By being configured in this manner, a light-emitting device with good wire bonding accuracy and a small size can be obtained.
Moreover, when the bottom surface which is the mounting surface side of a lead electrode protrudes from the said base part back surface, the said bottom surface can be comprised so that it may have a larger area than the said upper surface. With this configuration, the lead electrode also serves as a support for the light-emitting device and can be stably surface-mounted, and the contact area with the mounting substrate is widened, so that heat dissipation is improved. . The lead electrode having such a shape can be obtained by, for example, pressing the bottom side of the lead electrode formed in a columnar shape. Preferred shapes on the bottom surface side of the lead electrode include an inverted T shape, a divergent shape, an inverted taper type, and the like.

<Lid 6>
The light emitting device according to the present embodiment has a lid 6 composed of a translucent window portion 7 and a metal portion on the main surface side of the metal package. It is preferable that the window portion 7 is a light emitting surface of the light emitting device and is arranged at the center portion.

In the present embodiment, the window portion is located on the upper surface of the light emitting element disposed in the concave portion of the metal package, and has an intersection with an extension line of the inner wall of the concave portion. The light emitted from the end portion of the light emitting element is reflected and scattered by the side surface of the concave portion and extracted in the front direction. It is considered that the range in which these reflected scattered light exists is substantially within the extension line of the side surface of the recess. Therefore, by adjusting the area of the window, which is the light emitting surface, as described above, a light emitting device that can efficiently collect the reflected scattered light on the window and emit high-luminance light is obtained. It is done.
The lid base material is preferably similar in thermal expansion coefficient to the light transmitting member of the package body and window portion. Moreover, it is preferable that the surface of the material of a lid has a Ni plating layer as a protective film of a base material.

The lid, for example, uses a carbon sealing jig to seal the glass and the lid body in an airtight manner by placing a tablet-like glass in the opening formed in the lid body and passing it through a furnace. Can be made.
The shape of the lid is not particularly limited as long as it has a smooth flat surface that can be in close contact with the welded portion of the package and can hermetically seal the package. When a lid having a convex center portion is used, the color conversion member can be satisfactorily bonded to the back surface of the window portion of the lid, and a light emitting device can be formed with high yield. Further, when a flexible member is injected into the convex lid and the light emitting element electrically connected to the metal package is inserted and integrated, a light emitting device having excellent heat stress can be obtained.

  Further, when the surface of the window portion has a curved lens shape as shown in FIG. 7, the light convergence is good and a light emitting device having a high luminous intensity in the front direction can be obtained. For example, a shell formed by attaching a fluorescent material that has a directivity angle of about 45 degrees and absorbs part of the blue light and emits yellow light to a metal package on which a blue LED chip is mounted. When the side lens is placed, a miniaturized light emitting device capable of emitting a white beam with high luminance by mixing these colors can be obtained. Such a light-emitting device can be used for a flash application required for a drawing function provided in a small machine such as a mobile phone.

<Fluorescent substance 8>
The light-emitting device of the present invention combines a light-emitting element and a fluorescent material capable of absorbing at least part of light emitted from the light-emitting element and emitting other light, thereby providing light having a desired color tone. Obtainable. In addition, the fluorescent material is compatible with other members such as a diffusing agent and a pigment, and these materials can be used in combination. As an example of these arrangements, the lid window member may contain other substances such as the fluorescent substance 8, or the other substance layer may be applied to the inner surface of the window part using a binder. Good. Moreover, you may make it contain in resin etc. and arrange | position in the recessed part of a metal package.

Here, the fluorescent substance used in the present embodiment will be described in detail.
In the light-emitting device of this example, fluorescence based on a cerium-activated yttrium-aluminum oxide-based fluorescent material that can emit light by exciting light emitted from a semiconductor light-emitting element having a nitride-based semiconductor as a light-emitting layer. The substance is used.

Specific examples of the yttrium / aluminum oxide fluorescent material include YAlO ₃ : Ce, Y ₃ Al ₅ O ₁₂ : Ce (YAG: Ce), Y ₄ Al ₂ O ₉ : Ce, and a mixture thereof. It is done. The yttrium / aluminum oxide fluorescent material may contain at least one of Ba, Sr, Mg, Ca, and Zn. Moreover, by containing Si, the reaction of crystal growth can be suppressed and the particles of the fluorescent material can be aligned.
In this specification, the yttrium / aluminum oxide phosphor activated by Ce is to be interpreted in a broad sense, and a part or all of yttrium is selected from the group consisting of Lu, Sc, La, Gd and Sm. Or a part or all of aluminum is used in a broad sense including a phosphor having a fluorescent action in which any one or both of Ba, Tl, Ga, and In are substituted.

More specifically, the general formula _{(Y z Gd 1-z)} 3 Al 5 O 12: Ce ( where, 0 <z ≦ 1) photoluminescence phosphor and the general formula represented by _{(Re 1-a Sm a)} 3 Re ' ₅ O ₁₂ : Ce (where 0 ≦ a <1, 0 ≦ b ≦ 1, Re is at least one selected from Y, Gd, La, and Sc; Re ′ is selected from Al, Ga, and In At least one kind of photoluminescent phosphor.

  Since this fluorescent material has a garnet structure (garnet-type structure), it is resistant to heat, light and moisture, and the peak of the excitation spectrum can be made around 450 nm. In addition, the emission peak is in the vicinity of 580 nm and has a broad emission spectrum that extends to 700 nm.

  Further, the photoluminescence phosphor can increase the excitation light emission efficiency in a long wavelength region of 460 nm or more by containing Gd (gadolinium) in the crystal. As the Gd content increases, the emission peak wavelength shifts to a longer wavelength, and the entire emission wavelength also shifts to the longer wavelength side. That is, when a strong reddish emission color is required, it can be achieved by increasing the amount of Gd substitution. On the other hand, as Gd increases, the emission luminance of photoluminescence by blue light tends to decrease. Furthermore, in addition to Ce, Tb, Cu, Ag, Au, Fe, Cr, Nd, Dy, Co, Ni, Ti, Eu, and the like can be contained as desired.

  Moreover, in the composition of the yttrium / aluminum / garnet (garnet) phosphor having a garnet structure, the emission wavelength is shifted to the short wavelength side by substituting part of Al with Ga. Further, by substituting part of Y in the composition with Gd, the emission wavelength is shifted to the longer wavelength side.

  When substituting a part of Y with Gd, it is preferable that the substitution with Gd is less than 10%, and the Ce content (substitution) is 0.03 to 1.0. If the substitution with Gd is less than 20%, the green component is large and the red component is small. However, by increasing the Ce content, the red component can be supplemented and a desired color tone can be obtained without lowering the luminance. With such a composition, the temperature characteristics are good and the reliability of the light emitting diode can be improved. In addition, when a photoluminescent phosphor adjusted to have a large amount of red component is used, a light emitting device capable of emitting an intermediate color such as pink can be formed.

  Such photoluminescent phosphors use oxides or compounds that easily become oxides at high temperatures as raw materials for Y, Gd, Al, and Ce, and mix them well in a stoichiometric ratio. Get raw materials. Alternatively, a mixed raw material obtained by mixing a coprecipitation oxide obtained by firing a solution obtained by coprecipitation of a solution obtained by dissolving a rare earth element of Y, Gd, and Ce in an acid in a stoichiometric ratio with oxalic acid and aluminum oxide. Get. A suitable amount of fluoride such as barium fluoride or ammonium fluoride is mixed as a flux and packed in a crucible, and fired in air at a temperature range of 1350 to 1450 ° C. for 2 to 5 hours to obtain a fired product, and then fired. The product can be obtained by ball milling in water, washing, separating, drying and finally passing through a sieve.

  In the light emitting device of the present invention, such a photoluminescent phosphor may be a mixture of yttrium, aluminum, garnet (garnet type) phosphor activated by two or more kinds of cerium and other phosphors. .

  The particle size of the fluorescent material used in the present invention is preferably in the range of 10 μm to 50 μm, more preferably 15 μm to 30 μm. A fluorescent material having a particle size of less than 15 μm is relatively easy to form an aggregate, and is densely settled in a liquid resin, thus reducing the light transmission efficiency. In the present invention, by using such a fluorescent material that does not have a fluorescent material, concealment of light by the fluorescent material is suppressed and the output of the light emitting device is improved. In addition, the fluorescent material having a particle size range of the present invention has high light absorption and conversion efficiency and a wide excitation wavelength range. Thus, by including a large particle size fluorescent material having optically excellent characteristics, light around the dominant wavelength of the light emitting element can be converted and emitted well, and the mass productivity of the light emitting device is improved. Is done.

  Here, in the present invention, the particle size is a value obtained from a volume-based particle size distribution curve. The volume-based particle size distribution curve is obtained by measuring the particle size distribution by a laser diffraction / scattering method. Specifically, in an environment of an air temperature of 25 ° C. and a humidity of 70%, hexametalin having a concentration of 0.05%. Each substance was dispersed in an aqueous sodium acid solution and measured with a laser diffraction particle size distribution analyzer (SALD-2000A) in a particle size range of 0.03 μm to 700 μm. In this volume-based particle size distribution curve, it is a particle size value when the integrated value is 50%, and the central particle size of the fluorescent material used in the present invention is preferably in the range of 15 μm to 50 μm. Moreover, it is preferable that the fluorescent substance which has this center particle size value is contained frequently, and the frequency value is preferably 20% to 50%. In this way, by using a fluorescent material with small variation in particle size, a light emitting device having a favorable color tone with suppressed color unevenness can be obtained.

  The location of the fluorescent material is not particularly limited, and a binder may be provided on the back surface of the lid window, or it may be contained directly in the material of the lid window. In addition, a fluorescent substance may be contained in an inorganic material such as resin or glass that is relatively less deteriorated by heat, and the package recess may be filled so as to cover the light emitting element. Since the package of the present invention is made of metal and has excellent heat dissipation, even if the fluorescent material is filled around the light emitting element disposed in the recess by using a resin or the like, the components are hardly deteriorated by heat. In addition, the original action of the resin and the fluorescent substance can be utilized to the maximum.

In order to contain the fluorescent material directly in the window portion of the lid, for example, an opening is provided in the lid body, a mixture of glass powder or pellets and powder fluorescent material is placed in the opening, and press It is made into a batch by processing. Thereby, the fluorescent substance containing window part is formed. Alternatively, a glass paste mixed with a fluorescent substance may be disposed and fired.
In addition, when a fluorescent material is attached to the back surface of the lid window or the surface of the light emitting element with a binder, the material of the binder is not particularly limited, and either an organic material or an inorganic material can be used.

  When an organic substance is used as the binder, a transparent resin excellent in weather resistance such as an epoxy resin, an acrylic resin, or a silicone resin is suitably used as a specific material. In particular, it is preferable to use a silicone resin because it is excellent in reliability and can improve the dispersibility of the fluorescent substance. When an elastomeric or gel-like member is used, a light emitting device having excellent heat stress can be obtained.

Further, it is preferable to use an inorganic substance that is close to the thermal expansion coefficient of the window portion as the binder because the fluorescent material can be satisfactorily adhered to the window portion. As a specific method, a precipitation method, a sol-gel method, or the like can be used. For example, a phosphor, silanol (Si (OEt) ₃ OH), and ethanol are mixed to form a slurry, and the slurry is discharged from a nozzle to a lid window, and then heated at 300 ° C. for 3 hours. silanol and SiO _2, it is possible to fix the fluorescent substance.

  Further, an inorganic binder can be used as a binder. The binder is a so-called low-melting glass, is a fine particle and is preferably very stable in the binder with little absorption with respect to radiation from the ultraviolet to the visible region, and was obtained by a precipitation method. Alkaline earth borates, which are fine particles, are suitable.

In addition, when attaching a fluorescent substance having a large particle size, a binder whose particle is an ultrafine powder even if the melting point is high, such as silica, alumina made by Degussa, or a fine particle size alkali obtained by a precipitation method It is preferable to use an earth metal pyrophosphate or orthophosphate.
These binders can be used alone or mixed with each other.

  Here, a method for applying the binder will be described. In order to sufficiently enhance the binding effect, the binder is preferably used as a binder slurry by wet pulverization in a vehicle to form a slurry. The vehicle is a high viscosity solution obtained by dissolving a small amount of a binder in an organic solvent or deionized water. For example, an organic vehicle can be obtained by adding 1 wt% of nitrocellulose as a binder to butyl acetate as an organic solvent.

  A fluorescent substance is contained in the binder slurry thus obtained to prepare a coating solution. The amount of the slurry in the coating solution is preferably such that the total amount of the binder in the slurry is about 1 to 3% wt with respect to the amount of the fluorescent substance in the coating solution. If the amount of the binder added is too large, the luminous flux maintenance factor tends to decrease. Therefore, it is preferable to minimize the amount of use.

  In the case where it is desired to fix the fluorescent material to the rear face of the lid with the binder, the coating liquid is applied to the rear face of the window, and then hot air or hot air is blown and dried. Finally, baking is performed at a temperature of 400 ° C. to 700 ° C. to scatter the vehicle. Thereby, the phosphor layer is adhered to the surface of the window portion with the binder.

<Diffusion agent>
Further, in the present invention, the color conversion member may contain a diffusing agent in addition to the fluorescent material. As a specific diffusing agent, barium titanate, titanium oxide, aluminum oxide, silicon oxide or the like is preferably used. As a result, a light emitting device having good directivity can be obtained.

  Here, in this specification, the diffusing agent refers to those having a center particle diameter of 1 nm or more and less than 5 μm. A diffusing agent having a size of 1 μm or more and less than 5 μm is preferable because it diffuses light from the light-emitting element and the fluorescent material well and can suppress color unevenness that tends to occur by using a fluorescent material having a large particle size. In addition, the half width of the emission spectrum can be narrowed, and a light emitting device with high color purity can be obtained. On the other hand, a diffusing agent having a wavelength of 1 nm or more and less than 1 μm has a low interference effect on the light wavelength from the light emitting element, but has a high transparency and can increase the resin viscosity without reducing the luminous intensity. As a result, when the color conversion member is arranged by potting or the like, it becomes possible to disperse the fluorescent substance in the resin almost uniformly in the syringe and maintain the state, and the fluorescent substance having a large particle size that is relatively difficult to handle. Even when a substance is used, it is possible to produce with good yield. Thus, the action of the diffusing agent in the present invention varies depending on the particle size range, and can be selected or combined according to the method of use.

<Filler>
Furthermore, in the present invention, the color conversion member may contain a filler in addition to the fluorescent material. The specific material is the same as that of the diffusing agent, but the diffusing agent has a central particle size different from that of the diffusing agent. When the filler having such a particle size is contained in the translucent resin, the chromaticity variation of the light emitting device is improved by the light scattering action, and the thermal shock resistance of the translucent resin can be enhanced. As a result, even when used at high temperatures, it is possible to prevent disconnection of the wire that electrically connects the light emitting element and the external electrode, separation from the bottom surface of the light emitting element and the bottom surface of the concave portion of the package, etc. with high reliability. A light emitting device is obtained. Furthermore, the fluidity of the resin can be adjusted to be constant for a long time, and a sealing member can be formed in a desired place, enabling mass production with a high yield.

  The filler preferably has a particle size and / or shape similar to that of the fluorescent material. Here, in the present specification, the similar particle diameter means a case where the difference in the central particle diameter of each particle is less than 20%, and the similar shape means an approximate degree of each particle diameter with a perfect circle. This represents a case where the difference in the value of the degree of circularity (circularity = perimeter length of a perfect circle equal to the projected area of the particle / perimeter length of the projected particle) is less than 20%. By using such a filler, the fluorescent material and the filler interact with each other, and the fluorescent material can be favorably dispersed in the resin, thereby suppressing color unevenness. Furthermore, it is preferable that both the fluorescent substance and the filler have a central particle diameter of 15 μm to 50 μm, more preferably 20 μm to 50 μm. In this way, by adjusting the particle diameter, a preferable interval is provided between the particles. be able to. As a result, a light extraction path is ensured, and the directivity can be improved while suppressing a decrease in luminous intensity due to filler mixing.

  Hereinafter, the light-emitting device of the Example which concerns on this invention is explained in full detail. In addition, this invention is not limited only to the Example shown below.

Example 1.
A surface mount type light emitting device as shown in FIG. 1 is formed. The LED chip uses a nitride semiconductor element having a 475 nm In _0.2 Ga _0.8 N semiconductor having a monochromatic emission peak of visible light as a light emitting layer. More specifically, in the LED chip, TMG (trimethylgallium) gas, TMI (trimethylindium) gas, nitrogen gas and dopant gas are flowed with a carrier gas on a cleaned sapphire substrate, and a nitride semiconductor is formed by MOCVD. Can be formed. A layer to be an n-type nitride semiconductor or a p-type nitride semiconductor is formed by switching between SiH ₄ and Cp ₂ Mg as the dopant gas.

  As an element structure of the LED chip, an n-type GaN layer which is an undoped nitride semiconductor on a sapphire substrate, a GaN layer where an Si-doped n-type electrode is formed to become an n-type contact layer, and an n-type nitride semiconductor which is an undoped nitride semiconductor 5 layers of InGaN layers sandwiched between GaN layers, each comprising a type GaN layer, a GaN layer that constitutes a light emitting layer, a InGaN layer that constitutes a well layer, and a GaN layer that constitutes a barrier layer It is a multiple quantum well structure. On the light emitting layer, an AlGaN layer as a p-type cladding layer doped with Mg and a GaN layer as a p-type contact layer doped with Mg are sequentially laminated. (Note that a GaN layer is formed on the sapphire substrate at a low temperature to serve as a buffer layer. The p-type semiconductor is annealed at 400 ° C. or higher after film formation.)

  Etching exposes the surface of each pn contact layer on the same side as the nitride semiconductor on the sapphire substrate. Positive and negative pedestal electrodes were formed on each contact layer by sputtering. A metal thin film is formed on the entire surface of the p-type nitride semiconductor as a translucent electrode, and then a pedestal electrode is formed on a part of the translucent electrode. After drawing the scribe line on the completed semiconductor wafer, it is divided by an external force to form LED chips that are semiconductor light emitting elements.

  On the other hand, a Kovar package is used which has a concave portion in the center and a base portion in which Kovar lead electrodes are inserted and fixed in an insulating and airtight manner on both sides of the concave portion. A Ni / Ag layer is provided on the surface of the package and the lead electrode.

  An LED chip is die-bonded with an Ag—Sn alloy in the recess of the package thus configured. By constituting in this way, all the constituent members of the light emitting device can be made of an inorganic material, and a light emitting device with remarkably high reliability can be obtained.

  Here, as the bonding member used for die bonding, a resin or glass containing a conductive material can be used in addition to the above-described alloy. The conductive material contained is preferably Ag. When an Ag paste having a content of 80% to 90% is used, a light emitting device having excellent heat dissipation and low stress after bonding can be obtained.

  Next, the respective electrodes of the die-bonded LED chip and the respective lead electrodes exposed from the bottom of the package recess are electrically connected by Ag wires. Here, since the light-emitting device of this embodiment does not use an organic resin as a constituent member, an Al wire can also be used.

Next, after sufficiently removing moisture in the recesses of the package, the recesses are sealed with a Kovar lid having a glass window at the center, and seam welding is performed.
When a reliability test is performed on the light emission measure obtained in this way, when the light emission output is measured after 500 hours have passed under If = 500 mA, there is almost no difference from the relative output, and a large amount of current can be applied. Even so, a light emitting device capable of maintaining a high output for a long time can be obtained.

Example 2
When the light emitting device is formed in the same manner as in Example 1 except that the metal package is made of iron and the thickness of the base part is larger than the thickness of the bottom surface of the concave part, the heat dissipation is superior to that of Example 1 and the strength is higher. A strong light emitting device is obtained. As a result, both the reliability and the yield are improved, and a light-emitting device capable of maintaining a high output for a long time can be obtained with a high yield.

Example 3
As shown in FIG. 4, when the light emitting device is formed in the same manner as in Example 2 except that only the inner wall side of the recess of the metal package is tapered, the light emission output and mechanical strength are improved by 15% compared to Example 2.

Example 4
When the light emitting device is formed in the same manner as in Example 3 except that the translucent window is formed in a convex lens shape, the front luminous intensity is improved by 50% compared to Example 3.

Example 5 FIG.
As shown in FIG. 5, the light emitting device is formed in the same manner as in Example 3 except that the fluorescent material is contained in the lid window.
Here, as the fluorescent material, a solution obtained by dissolving rare earth elements of Y, Gd, and Ce in acid at a stoichiometric ratio is coprecipitated with oxalic acid. A co-precipitated oxide obtained by firing this and aluminum oxide are mixed to obtain a mixed raw material. This is mixed with barium fluoride as a flux and packed in a crucible and fired in air at a temperature of 1400 ° C. for 3 hours to obtain a fired product. The fired product is ball- _milled in water, washed, separated, dried, and finally passed through a sieve to have a center particle size of 22 μm (Y _0.995 Gd _0.005 ) _2.750 Al ₅ O ₁₂ : Ce _0.250 phosphor Form.

  The fluorescent material thus obtained and powdered silica are mixed at a ratio of 1: 2, placed in an opening provided in the lid, and collectively molded by pressing. The color conversion type light-emitting device obtained in this way can achieve the same effects as those of Example 1, and can emit white light with high reliability and high output.

Example 6
50 wt% of the above fluorescent material is contained in a slurry composed of 90 wt% of nitrocellulose and 10 wt% of γ-alumina, applied to the back surface of the transparent window portion of the lid, and cured by heating at 220 ° C for 30 minutes. When the light emitting device is formed in the same manner as in Example 3 except that the conversion member is configured, the same effect as in Example 5 is obtained.

Example 7
When the light-emitting device is formed in the same manner as in Example 6 except that the color conversion member is made of a silicone resin containing 50 wt% of a fluorescent substance, the same effect as in Example 6 is obtained.

Example 8 FIG.
When the light-emitting device was formed in the same manner as in Example 6 except that the color conversion member was formed by applying silica-gel containing 50 wt% of a fluorescent substance to the color conversion member, the same effect as in Example 6 was obtained. Is obtained.

Example 9
When a light emitting device is formed in the same manner as in Example 3 except that a color conversion member is formed by filling a silicone resin containing a fluorescent material into the recess of the package, a light emitting device having a higher front luminance than that in Example 5 is obtained. In addition, by coating the light emitting element with resin, the point light source can be a surface light source and the light color mixing is excellent, so that uniform light emission can be obtained without color variation due to angle. Further, when an elastomeric silicone resin or a gel-like silicone resin is used as the silicone resin, a light emitting device having excellent heat stress is obtained, and the reliability is improved.

Example 10
A surface mount type light emitting device as shown in FIG. 9 is formed. With the taper-shaped mold installed on the back side of the center of the base plate made of iron, the metal is drawn from the main surface direction to flow the metal to the back and main surfaces. A concave portion having a thin bottom surface thickness and having an edge protruding from an adjacent base portion on the main surface side and having a tapered inner wall is integrally formed. By forming in this way, a light-emitting device having excellent reliability and light extraction efficiency can be obtained with high productivity.
Next, two through holes are formed in the thickness direction along one end surface in the base portion surrounding the recess.

  On the other hand, a T-shaped lead electrode having a larger area on the main surface side than that on the bottom surface side is formed by Kovar, and Ni / Au plating is applied to the surface. The lead electrode thus formed is inserted into the through hole from the main surface side. Here, since the lead electrode has a T shape, positioning is easy when inserted into the through hole, and the lead electrode can be fixed with high accuracy. Next, the main surface side of the lead electrode is fixed to a carbon jig having a recess that matches the main surface size, glass is applied to the interface between the through hole and the lead electrode, and the interface is melted. Seal hermetically. Since the area of the main surface of the lead electrode is designed to be large, it can be fixed to the carbon jig with high stability. Thereby, the airtight sealing of the interface can be performed with high accuracy. In the light emitting device of this embodiment, the main surface side of the package is hermetically sealed with nitrogen gas. Thereby, metal migration is prevented on the main surface side, and the area on the main surface side of the lead electrode can be maximized. Thereby, after stitch-bonding and cutting a wire on the main surface of each lead electrode, the stitch bonding portion can be reinforced with another metal piece. Specifically, after the first stitch bonding is performed on the surface of the lead electrode and the wire is cut, a reinforcing ball is formed with a separate wire so as to cover at least a part of the first stitch bonding, and the wire is used as it is. The second stitch bonding is performed by pulling up the upper portion and moving the wire to the opposite side of the wire connected to the LED chip through the center of the reinforcing ball and covering the first stitch bonding through the reinforcing ball. To cut the wire. Such a reinforcing metal piece is configured such that the second ball bonding portion and the second stitch bonding are all arranged in one direction on the first stitch bonding portion. As a result, weighting and ultrasonic application by each bonding, that is, weighting and ultrasonic application of 3 times in total are applied intensively in the one direction, and the adhesion strength with the lead electrode can be increased. The first stitch bonding portion and the second stitch bonding portion are preferably substantially symmetric with respect to the reinforcing ball, whereby the first stitch bonding portion and the second stitch bonding portion are The film thickness of the second ball bonding part interposed between them is almost uniform, and the weight and ultrasonic wave applied by the second stitch bonding can be transmitted evenly over the entire surface in the one direction, and the bonding strength is uniformly enhanced. Can do. When bonding reinforcement is performed in this manner, high reliability can be maintained even when bonding conditions are not good.

  In addition, since the surface area of the lead electrode can be increased, a plurality of wires can be bonded to each lead electrode surface with high accuracy. For example, a large chip type light emitting device having a plurality of light emitting regions can emit light at a high output by dropping a large current. In order to prevent wire fusing due to self-heating, it is preferable to make electrical connection with a plurality of wires, and the package of this embodiment can mount such a light emitting element with high reliability. Also, when a protective element is separately placed on the base for the purpose of increasing the electrostatic withstand voltage of the light emitting element, the light emitting element and the protective element are respectively wire bonded to the lead electrode, and the main surface of one lead electrode However, by using the package of this embodiment, a light-emitting device with high reliability and excellent optical characteristics can be formed with high productivity. On the other hand, since the bottom side is in contact with air, it is preferable to reduce the surface area in consideration of the occurrence of migration.

  In the present embodiment, the lead electrodes are arranged along one end face of the package. With this configuration, it is possible to simplify the electrode wiring of the mounting substrate and to widen the area for heat dissipation. Moreover, the variation of the mounting pattern is preferable because it is abundant. Further, when a protective element is placed separately from the light emitting element in order to increase reliability, the protective element is preferably placed between the lead electrodes along the one end surface. As a result, the length of the wire bonded from the protective element to the main surface of each lead electrode can be shortened as much as possible, and the reliability can be improved without adversely affecting the optical characteristics.

  In addition, it is preferable that the edge main surface of the recess is located substantially on the same plane as the main surface of each lead electrode, thereby improving wire bonding accuracy and reducing the thickness of the light emitting device with high reliability. A device is obtained. Moreover, it is preferable that the main surface of the edge part located between the said recessed part and each said lead electrode among the edge parts of the said recessed part is comprised lower than the said base part main surface, The corner formed by the inner wall is preferably rounded. Thereby, the loop height of the wire can be further reduced, and both improvement in brightness and reduction in thickness can be realized. The edge portion whose height is partially adjusted in this way can be integrally formed by pressing at the time of forming the recess.

  Next, in the base portion, a support is formed by pressing from the main surface side and flowing a part of the metal toward the bottom surface side at two locations facing each lead electrode through the concave portion. The bottom surface of the support is located on substantially the same plane as the bottom surface of the lead electrode and the bottom surface of the recess. Thereby, the light-emitting device excellent in mountability and heat dissipation is obtained.

  An LED chip having two positive and negative electrodes on the same surface side is die-bonded with an Ag—Sn alloy in the concave portion of the package thus configured. It is preferable that the LED chip is placed so that the side surface that emits light faces the protruding edge of the recess. Specifically, the chip is placed so that the corner of the chip faces each of the lead electrodes. By mounting in this manner, the light emitting device can be thinned without reducing the light extraction efficiency. The two positive electrodes of the LED chip are electrically connected to the main surface of one lead electrode by an Au wire, and the two negative electrodes are electrically connected to the main surface of the other lead electrode by an Au wire. As described above, a light emitting device having two or more electrodes has excellent light emission output, but a relatively large amount is accompanied by a heat generation amount. However, the package of the present invention has excellent heat dissipation without impairing reliability. A high-power light-emitting device can be formed. In addition, since the area on the main surface side of each lead electrode is large, a plurality of wires can be bonded with high reliability. In this embodiment, since each lead electrode is arranged on one end side, even if the main area of the lead electrode is further increased as desired, it is sufficient to enlarge the package only in one direction, and the large size of the light emitting device. Can be minimized.

Next, after removing moisture in the concave portion of the package, the LED chip and the wire are covered with a Kovar lid having a glass window at the center, and hermetically sealed with nitrogen gas to perform seam welding.
Here, the glass window portion preferably intersects with an extension line of the inner wall of the recess, and further, the rising point of the inner wall facing the side surface of the light emitting element and the inner wall facing the light emitting element via the light emitting element. It is preferable to intersect with a straight line connecting the uppermost end point. By designing the area of the window in this manner, the light reflected and scattered by the inner wall can be efficiently extracted to the outside.
The light emitting device thus obtained has higher light output and mechanical strength than Example 3.

Example 11
As shown in FIG. 10, the fluorescent material 8 (Y _0.995 Gd _0.005 ) _2.750 Al ₅ O ₁₂ : Ce _{. A} light emitting device is formed in the same manner as in Example 10 except that a continuous color conversion layer having ₂₅₀ and SiO ₂ is formed by spray coating. Here, a method for forming the color conversion layer will be described in detail.

Step 1.
Although methyl silicate, ethyl silicate, N-propyl silicate, and N-butyl silicate can be used as the alkyl silicate, a colorless and transparent oligomer liquid obtained by condensing ethyl silicate containing 40 wt% of SiO ₂ is used in this embodiment. In addition, ethyl silicate is used that has been made into a sol by reacting with water in the presence of a catalyst in advance to cause a hydrolysis reaction.

  First, a coating solution is prepared by stirring a solution in which sol-form ethylsilicate, ethylene glycol, and a fluorescent substance are mixed at a weight ratio of 1: 1: 1. Here, since sol-like ethylsilicate is easy to dry, it is preferable to prevent gelation by mixing with a high boiling point (100 ° C. to 200 ° C.) organic solvent such as butanol or ethylene glycol. When mixed with a high-boiling organic solvent in this way, clogging of the nozzle tip due to gelation of the sol-like ethyl silicate can be prevented and work efficiency can be improved.

Step 2.
The coating liquid is placed in the container 18, and the coating liquid is conveyed from the container to the nozzle 17 by the circulation pump 20. The flow rate of the coating liquid is adjusted by a valve 19. Here, the mist-like coating liquid ejected from the nozzle 17 is sprayed while being rotated in a mist-like and spiral manner. Specifically, the spray spreads in a conical shape in the vicinity of the nozzle, and spreads in a cylindrical shape as the distance from the nozzle increases. Accordingly, the upper surface, side surfaces, and corners of the light emitting element can be covered with a continuous color conversion layer in which the film thickness is substantially equal and the fluorescent material is uniformly dispersed, and color unevenness such as blue ring is obtained. Can be improved. The color conversion layer is preferably composed of a single particle layer, which improves the light extraction efficiency. In this embodiment, the distance from the upper surface of the light emitting element to the lower end of the nozzle is set to 40 to 50 mm so that the surface of the light emitting element is placed in a state where the spray spreads in a cylindrical shape, and as shown in FIG. A continuous color conversion layer having a substantially uniform film thickness is formed on the top surface, side surfaces, and corners of the light emitting element, and further on the inner surface of the recess.

  Moreover, the said process is performed in the state which heated the place to apply | coat. As a result, the ethanol or solvent generated by the sol-formation of ethyl silicate can be instantaneously blown onto the light emitting element. Accordingly, the color conversion layer can be provided without adversely affecting the light emitting element. In the present embodiment, spray coating is performed while the package on the heater 15 is placed, and the temperature of the heater is preferably adjusted to a temperature of 50 ° C. or higher and 300 ° C. or lower.

Step 3.
After performing the procedure 2, it is allowed to stand at room temperature, the sol-like ethyl silicate reacts with moisture in the air, and the fluorescent substance is fixed by SiO ₂ .

Step 4.
Next, it is dried at a temperature of 300 ° C. for 2 hours. When nitride-based light-emitting elements are placed at a temperature of 350 ° C. or higher, the performance as the light-emitting elements deteriorates. Therefore, alkyl silicates that can be fixed to the surface of the light-emitting elements at a temperature of 300 ° C. It can be preferably used as an agent.

  Since all the light emitting devices configured as described above are made of an inorganic material, the light emitting device has high heat dissipation and also has excellent light resistance to near vision and ultraviolet light. The light emitting device of this embodiment can use any element such as a light emitting element that emits light in the ultraviolet region.

Example 12 FIG.
As the fluorescent material, the first fluorescent material (Y _0.995 Gd _0.005 ) _2.750 Al ₅ O ₁₂ : Ce _0.250 and the second fluorescent material Ca _1.8 Eu _0.2 Si ₅ N ₈ If a light emitting device is formed in the same manner as in Example 11 except that a mixture and dispersion of is used, a light emitting device having better color rendering than in Example 11 is obtained. The second fluorescent material that can be used in this embodiment is not particularly limited, but MxSiyNx: Eu () having an excitation wavelength similar to that of the first fluorescent material and capable of emitting yellow to red fluorescence. However, when M is at least one alkaline earth metal selected from the group of Ca, Sr, Ba, and Zn, z = 2 / 3x + 4 / 3y), it is preferable because light having excellent color rendering properties can be obtained.

Example 13
When a light emitting device was formed by the same method as in Example 11 except that the phosphor was bound by adjusting the coating solution using a fluororesin (PTFE = polytetrafluoroethylene) instead of ethyl silicate, Example 11 And a good production yield can be obtained.

Example 14
Example 11 except that an LED chip having a dominant wavelength of 400 nm is used as the light-emitting element, and (Sr _0.96 , Eu _0.01 , Mn _0.03 ) ₁₀ (PO ₄ ) ₆ Cl ₂ is used as the fluorescent material. Similarly, a light emitting device is formed.

Here, a method for forming the fluorescent material will be described. First, SrHPO ₄ , SrCO ₃ , Eu ₂ O ₃ , MnCO ₃ , and NH ₄ Cl as raw materials are adjusted and mixed so as to have the above composition ratio. (SrHPO ₄ : 1000 g, SrCO ₃ : 482.4 g, Eu ₂ O ₃ : 16.0 g, MnCO ₃ : 35.2 g, NH ₄ Cl: 116.5 g)

Next, the raw materials are weighed and thoroughly mixed by a dry method using a mixer such as a ball mill. This mixed raw material is packed in a crucible made of SiC, quartz, alumina or the like, heated to 1200 ° C. at 960 ° C./hr in a reducing atmosphere of N ₂ and H ₂ , and fired at a constant temperature part 1200 ° C. for 3 hours. The obtained fired product is pulverized, dispersed, sieved, separated, washed with water, and dried in water to obtain the desired phosphor powder.
When the fluorescent material thus obtained is applied to the periphery of the light emitting element and the inner surface of the recess in the same manner as in Example 11, a light emitting device capable of emitting light with high luminance is obtained.

Example 15.
CaHPO ₄ , CaCO ₃ , Eu ₂ O ₃ , MnCO ₃ , NH ₄ Cl, and NH ₄ Br are used as raw materials (Ca _0.93 , Eu _0.05 , Mn _0.02 ) ₁₀ (PO ₄ ) ₆ Br ₁ Adjust and mix to a composition ratio of _0.0 Cl _1.0 .
The raw materials are weighed and mixed thoroughly by a dry method using a mixer such as a ball mill. This combined raw material is packed in a crucible made of SiC, quartz, alumina or the like, heated to 1200 ° C. at 960 ° C./hr in a reducing atmosphere of N ₂ and H ₂ , and fired at a constant temperature part 1200 ° C. for 3 hours. The obtained fired product is pulverized, dispersed, sieved, separated, washed with water, and dried in water to obtain the desired phosphor powder. A light emitting device capable of emitting light with high luminance can be obtained by coating the periphery of the light emitting element and the inner surface of the recess in the same manner as in Example 14 except that this fluorescent material is used to form a color conversion layer.

Example 16
As the fluorescent material, the first fluorescent material (Y _0.995 Gd _0.005 ) _2.750 Al ₅ O ₁₂ : Ce _0.250 and the second fluorescent material (Ca _0.93 , Eu _0.05 , Mn _{0 0.02} ) ₁₀ (PO ₄ ) ₆ Br _1.0 Cl _1.0 A white light source capable of emitting light with high luminance when a light emitting device is formed in the same manner as in Example 14 except that a mixture is dispersed. Is obtained.

Example 17.
(Ca _0.93 , Eu _0.05 , Mn _0.02 ) ₁₀ (PO ₄ ) ₆ Br _1.0 Cl _{1.0 A} coating liquid composed of a fluorescent substance and Al ₂ O _{3 is} applied to the periphery of the light emitting element and the concave inner surface After the first color conversion layer is formed by spraying, Y _0.995 Gd _0.005 ) _2.750 Al ₅ O ₁₂ : Ce _0.250 phosphor is in contact with the first color conversion layer. A light emitting device is formed in the same manner as in Example 14 except that the second color conversion layer formed by fixing with SiO ₂ using sol-like ethyl silicate is formed in the same manner as in Example 11. By forming in this way, the optical refractive index of the second color conversion layer <the optical refractive index of the first color conversion layer <the refractive index of the gallium nitride compound semiconductor layer, and the light from the light emitting element can be obtained. A light-emitting device capable of emitting light at high output with increased extraction efficiency can be obtained.

  The light-emitting device of the present invention uses a highly reliable metal package and is configured so that the place where the light-emitting element is disposed is in contact with the mounting substrate, thereby greatly improving heat dissipation and dropping a large current. In addition, high reliability can be maintained without deterioration. As a result, a light-emitting device that can emit light with high reliability and brightness equivalent to that of lighting for a long time can be realized, and the industrial utility value is extremely high.

It is a typical top view which shows the light-emitting device of this invention. It is typical sectional drawing which shows the light-emitting device of this invention. It is a typical top view which shows the other light-emitting device of this invention. It is typical sectional drawing which shows the other light-emitting device of this invention. It is a typical top view which shows the other light-emitting device of this invention. It is typical sectional drawing which shows the other light-emitting device of this invention. It is typical sectional drawing which shows the other light-emitting device of this invention. It is typical sectional drawing which shows the other light-emitting device of this invention. It is typical sectional drawing which shows the other light-emitting device of this invention. It is typical sectional drawing which shows the other light-emitting device of this invention. It is typical sectional drawing which shows the other light-emitting device of this invention. It is a typical top view which shows the other light-emitting device of this invention. It is typical sectional drawing in the AA 'line of FIG. 9A. It is typical sectional drawing which shows the other light-emitting device of this invention. FIG. 11 is a schematic view showing a step of forming the light emitting device of FIG. 10. It is typical sectional drawing of the light-emitting device shown for comparison with this invention. It is typical sectional drawing of the light-emitting device shown for comparison with this invention. It is a schematic diagram which shows the apparatus used for 1 process of forming the light-emitting device of FIG. FIG. 15 is a schematic plan view in which one light emitting device of the present invention is mounted on a high thermal conductivity substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting element, 2 Lead electrode, 3 Insulation member, 4 Wire, 5 Package, 6 Lid, 7 Translucent window part, 8 Fluorescent substance, 27 Mounting board, 28 High heat conductivity area | region, 29 Wiring, a recessed part, b Base part.

Claims (6)

A light emitting element;
A metal package comprising a recess housing the light emitting element and a base having at least one through hole;
A lid composed of a light-transmitting window and a metal part, and sealing a recess of the metal package;
A light-emitting device having a lead electrode that is electrically separated from the metal package by an insulating member and inserted into the through-hole so that a tip portion thereof protrudes from a bottom surface of the base portion;
The concave surface, which is the outer surface facing the surface on which the light emitting element is mounted, has a metal surface that constitutes the metal package exposed, and the concave surface where the metal surface is exposed, the bottom surface of the lead electrode, There coplanar, the window portion have a fluorescent substance,
In the metal package, the bottom surface side of the concave portion of the side wall constituting the concave portion is thicker than the bottom surface portion of the concave portion .   The light emitting device according to claim 1, wherein a thickness of the base portion is greater than a thickness of a bottom surface of the concave portion.   The light emitting device according to claim 1, wherein a bottom surface of the concave portion has an inverted convex shape.   The light emitting device according to claim 1, wherein an inner wall of the concave portion has a tapered shape.   The light-emitting device according to claim 1, further comprising a support body on a back side of the base portion.   6. The light emitting device according to claim 1, further comprising a groove between the bottom surface of the recess and the bottom surface of the lead electrode.

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