JP2007096236A - Led light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED light emitting device in which miniaturization can be achieved while ensuring high heat dissipation. <P>SOLUTION: The LED light emitting device comprises an LED chip, a thermally conductive frame for mounting the LED chip, a pair of lead frames to which the electrodes of the LED chip are connected, and a reflector covering part of the thermally conductive frame and part of the lead frame and forming a cup-like reflecting surface around the LED chip wherein the light exit direction of the LED chip is substantially perpendicular to the elongating direction of the lead frame. Exposed portion of the thermally conductive frame is equipped with a packaging region elongating along the elongating direction of the lead frame and secured, at a part thereof, to a wiring board when the distal end of the lead frame is secured to the wiring board. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an LED light emitting device. Specifically, the present invention provides a technique related to the downsizing and improvement of heat dissipation of an LED light emitting device.

In a backlight of a liquid crystal display or the like, an LED is used as a light source for obtaining planar light (or linear light). In the configuration of the edge light system generally adopted, the light from the LED light source is introduced from the end face (edge) of the light guide plate and taken out from the upper surface of the light guide plate. In such an edge light system, an LED light source is disposed in the vicinity of the end face of the light guide plate in order to efficiently introduce light into the light guide plate. Along with this, wiring boards and connectors on which the LED light source is mounted are also arranged in the vicinity of the end face of the light guide plate, but there are many cases where sufficient space for arranging the wiring boards and connectors cannot be secured. Design becomes very difficult.
When the space near the end face of the light guide plate is limited, for example, the configuration shown in FIG. 12 can be adopted. In this example, the lead frame 101 of the bullet-type LED lamp 100 is bent, so that the wiring board 102 can be arranged in parallel to the light guide plate 103, and space saving is achieved. In addition, although it is not the technique regarding an LED light source device, the same structure is disclosed by patent document 1. FIG.
On the other hand, with the increase in brightness of the LED light source, a positive heat dissipation measure is required. Conventionally, as a heat dissipation measure, a method of installing a heat sink via a heat conductive material such as a metal layer behind the LED light source is generally used (see, for example, Patent Documents 2 to 4).
Japanese Patent Laid-Open No. 5-145091 JP 2004-265626 A Special Table 2004-528698 JP 2005-513815 A

Although the size reduction is achieved in the configuration shown in FIG. 12, a step of bending the lead frame of the LED lamp is required in the manufacturing process. Therefore, the number of processes for mounting increases. In addition, when the lead frame is bent, control is required so that the optical axis of the LED lamp is at a desired angle, leading to a decrease in yield.
On the other hand, regarding heat dissipation measures, it is difficult to reduce the size by providing a separate heat sink as in the conventional configuration. Moreover, there is a possibility that the heat radiation efficiency may be lowered due to the thermally conductive material interposed in the middle.
Then, this invention makes it a subject to provide the LED light-emitting device which achieves size reduction, ensuring high heat dissipation, without complicating the mounting process. It is another object of the present invention to provide an LED light emitting device with high mounting reliability.

In order to solve the above problems, the present invention has the following configuration. That is,
An LED chip;
A thermally conductive frame on which the LED chip is mounted;
A pair of lead frames to which the electrodes of the LED chip are connected;
A reflector that covers a part of the thermally conductive frame and a part of the lead frame and forms a cup-shaped reflective surface around the LED chip;
The light emitting direction of the LED chip is substantially perpendicular to the extending direction of the lead frame;
The exposed portion of the thermally conductive frame is a region extending along the extension direction of the lead frame, and when the tip of the lead frame is fixed to the wiring substrate, a part of the exposed portion is similarly attached to the wiring substrate. It is a LED light-emitting device provided with the area | region for mounting to be fixed.

In the above configuration, since the light emission direction of the lead frame and the LED chip is substantially vertical, if the device is mounted according to a normal mounting process so that the lead frame is substantially perpendicular to the wiring board, the light emission direction of the LED chip Is substantially parallel to the wiring board, and an arrangement mode suitable for miniaturization in which the wiring board is arranged in parallel to the light guide plate can be achieved. In this way, it is possible to achieve downsizing in the case of using the light guide plate without requiring an additional process for mounting. On the other hand, by mounting the LED chip on the heat conductive frame, the heat from the LED chip is transmitted through the heat conductive frame and is dissipated from the portion (exposed portion) not covered by the reflector of the frame. Thus, since the heat from the LED chip is directly dissipated through the thermally conductive frame incorporated in the package, efficient heat dissipation can be achieved while achieving downsizing. Moreover, as a result of improving heat dissipation, it becomes a structure which can respond also to a LED chip with high output. Further, since the heat conductive frame includes the mounting region as described above, the heat conductive frame is fixed to the wiring board in addition to the lead frame at the time of mounting. As a result, the mounting reliability is higher than when only the lead frame is fixed.
As a result of the above operations and effects, the device using the LED light-emitting device of the present invention as a light source is small in size, excellent in heat dissipation characteristics, and excellent in mounting reliability.

Hereafter, each element which comprises this invention is demonstrated.
(LED chip)
The kind of LED chip is not particularly limited, and an arbitrary configuration can be adopted. For example, an LED chip including a group III nitride compound semiconductor layer can be used. Group III nitride compound semiconductor is represented by the general formula _{Al X Ga Y In 1-X} -Y N (0 ≦ X ≦ 1,0 ≦ Y ≦ 1,0 ≦ X + Y ≦ 1), AlN, GaN and It includes a so-called binary system of InN, a so-called ternary system of Al _x Ga _1-x N, Al _x In _1-x N, and Ga _x In _1-x N (where 0 <x <1).

The group III nitride compound semiconductor may contain an arbitrary dopant. As the n-type impurity, silicon (Si), germanium (Ge), selenium (Se), tellurium (Te), carbon (C), or the like can be used. As the p-type impurity, magnesium (Mg), zinc (Zn), beryllium (Be), calcium (Ca), strontium (Sr), barium (Ba), or the like can be used. Although the group III nitride compound semiconductor can be exposed to electron beam irradiation, plasma irradiation or furnace heating after doping with p-type impurities, it is not essential.
Group III nitride compound semiconductors include metalorganic vapor phase epitaxy (MOCVD), well-known molecular beam crystal growth (MBE), halide vapor phase epitaxy (HVPE), sputtering, ion plating. It can also be formed by a ting method or the like.

  The material of the substrate on which the group III nitride compound semiconductor layer is grown is not particularly limited as long as the group III nitride compound semiconductor layer can be grown. For example, sapphire, gallium nitride, spinel, silicon, silicon carbide, Examples of the substrate material include zinc oxide, gallium phosphide, gallium arsenide, magnesium oxide, manganese oxide, and a group III nitride compound semiconductor single crystal. Among these, it is preferable to use a sapphire substrate, and it is more preferable to use the a-plane of the sapphire substrate.

  The emission color of the LED chip is appropriately selected according to the purpose. For example, it is selected according to a desired emission color such as blue, red, and green. A plurality of LED chips can also be used. In that case, it is possible to combine a plurality of different types of LED chips as well as a combination of the same types of LED chips. For example, one type or two or more types of LED chips having different emission colors are used so that white light is finally obtained.

In one embodiment of the present invention, an LED chip and a phosphor are used in combination. Then, white light is obtained by mixing (mixing) the light of the LED chip and the fluorescence generated from the phosphor using a part of the light of the LED chip. For example, the phosphor is contained in a sealing member described later.
The kind of fluorescent substance is not specifically limited, It can employ | adopt regardless of an organic type and an inorganic type. Phosphors having various fluorescent colors can be adopted. For example, phosphors having red, green, or blue fluorescent colors, which are the three primary colors of light, as well as phosphors that fluoresce intermediate colors thereof (for example, yellow fluorescent materials) Body). A plurality of phosphors can be used in combination. For example, a red phosphor, a green phosphor, and a blue phosphor can be mixed and used.

  The LED chip is mounted on the thermally conductive frame so that its optical axis is perpendicular to the direction of extension of the lead frame. As a result, in the LED light emitting device of the present invention, light is emitted in a direction perpendicular to the legs of the lead frame.

(Thermal conductive frame)
The thermally conductive frame functions as a heat sink for dissipating heat from the LED chip. The thermally conductive frame includes a region where the LED chip is mounted. A part of the heat conductive frame is covered with a reflector. That is, it is configured integrally with the reflector. In the thermally conductive frame, a portion protruding from the reflector to the outside, that is, an exposed portion becomes a heat radiating portion, and the heat of the LED is dissipated therein. In order to achieve efficient heat dissipation, the ratio of the exposed portion should be increased. Specifically, the volume of the exposed portion is, for example, 30% (v / v) or more, preferably 50% (v / v) or more, more preferably 70% (v / v) or more of the entire volume of the heat conductive frame. Thus, the size of the exposed portion can be designed. Further, increasing the surface area of the exposed portion as much as possible is effective in improving the heat dissipation characteristics. Therefore, for example, an exposed portion including fins or protrusions (hereinafter, these are collectively referred to as heat radiation fins). In particular, if the exposed portion includes a plurality of heat radiating fins, heat can be radiated more efficiently by the air flow generated between the heat radiating fins.
By bending a part of the thermally conductive frame formed into a flat plate shape, a heat radiating fin constituting the exposed portion can be formed. Specifically, for example, the heat radiation fin is formed by bending a part of the edge of the thermally conductive frame. As another example, a heat radiation fin may be formed by punching a part of a region that becomes an exposed portion in the thermally conductive frame (for example, a U-shape) and erecting a region surrounded by the punched portion. According to such a method, an exposed portion having a plurality of heat radiation fins can be easily produced.
The shape of the exposed part is not particularly limited. Moreover, an exposed part may be provided in several places and a heat dissipation effect may be improved.

  In the exposed portion of the thermally conductive frame, a mounting region is formed that extends along the extension direction of the lead frame described later. A part of the mounting region (for example, the tip) is formed in a protruding shape, and is fixed to the wiring board in the same manner as the tips of the pair of lead frames when the device is mounted. When the exposed part of the thermal conductive frame is provided with such mounting area, the thermal conductive frame is fixed to the wiring board in addition to the lead frame when mounting the device, improving the mounting reliability. To do.

  It is preferable that the heat conductive frame is exposed on both the left and right sides of the reflector, and a mounting region is formed in each exposed portion. According to this form, when mounting the device, the fixing to the wiring board can be performed at a total of four locations, that is, the tips of the pair of lead frames and the tips of the exposed portions. In addition, since the exposed portions are located on both the left and right sides of the reflector, and the mounting area of each exposed portion is fixed to the wiring board on both the left and right sides of the reflector, more reliable mounting is possible.

  It is preferable that a part of the mounting region of the thermally conductive frame to be fixed to the wiring board is at a position offset from the tip of the lead frame. According to such a configuration, the apparatus can be mounted in a stable posture, and mounting accuracy and mounting reliability are improved.

  When a part of the mounting area of the heat conductive frame is fixed to the wiring board, the heat conductive frame preferably includes a portion (locking portion) to be locked to the wiring board. According to such a configuration, the device can be positioned with respect to the wiring board using the locking portion, and the mounting area can be more securely fixed to the wiring board.

  Examples of the material of the heat conductive frame include aluminum, aluminum alloy, copper, and copper alloy.

(Lead frame)
The LED light-emitting device of the present invention includes a pair of lead frames. The electrode of the LED chip is electrically connected to the lead frame. A part of the lead frame is covered with a reflector. The exposed portion (lead leg) of the lead frame is substantially linear.
The LED light-emitting device of the present invention is suitable as a light source for a backlight using a light guide plate, taking advantage of the feature that the light emission direction is perpendicular to the extension direction of the lead frame (see examples described later). When used in such applications, the light guide plate is disposed in parallel with a predetermined interval with respect to the wiring board on which the LED light emitting device is mounted. That is, the light guide plate is disposed on the optical axis of the LED light emitting device. In order to realize such an arrangement mode, the length of the lead leg of the LED light-emitting device is preferably made longer than that of a normal LED light-emitting device. For example, the lead leg is about 10 mm to 30 mm. Preferably, the lead foot is 15 mm to 20 mm.

(Reflector)
The reflector (reflecting member) covers a part of the heat conductive frame and a part of the pair of lead frames, and forms a cup-shaped reflecting surface around the LED chip. This reflection surface reflects light emitted from the LED chip in the horizontal or oblique upward direction, and converts it into light in the light extraction direction. The cup shape here refers to a shape surrounding a space where the area of the cross section perpendicular to the optical axis of the LED chip increases continuously or stepwise from the bottom side toward the light extraction direction of the light emitting device. The shape of the reflecting surface is not particularly limited as long as such a condition is satisfied.

The material for forming the reflector is not particularly limited, and an appropriate material can be selected and used from metals, alloys, synthetic resins, and the like. However, the surface facing the LED chip, that is, the reflecting surface is required to be reflective to the light of the LED chip. For example, the reflector can be made of a resin having a high light reflectance such as a white resin. Resin-made reflectors have the advantage of being easy to mold.
On the other hand, when a material that does not have high reflectivity for the light of the LED chip is selected as the material of the reflector, a layer having a high reflectance is formed at least on the surface of the region that becomes the reflective surface. Such a reflective layer can be made of, for example, one or more metals selected from Al, Ag, Cr, Pd, and the like, or alloys thereof. In addition, metal nitrides such as titanium nitride, hafnium nitride, zirconium nitride, and tantalum nitride can also be used as the material of the reflective layer. In particular, the reflective layer is preferably made of Al or an alloy thereof. For the formation of the reflective layer, methods such as vapor deposition, coating, and printing can be employed. In particular, according to the vapor deposition method, a reflective layer having a uniform thickness and a smooth surface can be easily formed. The reflective layer does not necessarily have to be formed on the entire inner peripheral surface of the cup-shaped part, but is emitted laterally or obliquely upward from the LED chip so that the effect of improving the luminous efficiency by the reflective layer is maximized. It is preferable to provide a reflection layer on the entire area irradiated with the light.
The thickness of the reflective layer is not particularly limited as long as it is sufficient to reflect the light from the LED chip, and is, for example, in the range of about 0.1 to about 2.0 μm. Preferably, it is in the range of about 0.5 to about 1.0 μm.
Even when the reflector is manufactured using a material having excellent light reflectivity, a layer made of a highly light-reflective material may be formed on the surface of the portion serving as the reflective surface.

The surface of the reflecting surface is preferably as smooth as possible. This is because specular reflection on the reflecting surface is more likely to occur as the surface becomes smoother, so that the reflection efficiency can be improved and the light emission efficiency can be improved.
The angle of the reflecting surface of the reflector can be designed in consideration of the reflection efficiency in the optical axis direction, and is preferably in the range of 20 ° to 60 ° with respect to the optical axis of the LED chip. More preferably, it is in the range of 40 ° to 50 °.

  By forming the reflector with a material having high thermal conductivity, the heat dissipation characteristics of the light-emitting device can be improved. Examples of the material having high thermal conductivity include metals such as aluminum (Al) and copper (Cu) or alloys thereof. If the reflecting member is made of a material having high thermal conductivity, part of the heat dissipation of the LED chip can be performed via the reflecting member, and the heat dissipation characteristics of the light emitting device are improved.

(Sealing member)
The cup-shaped portion of the reflector may be filled with a material for sealing the LED chip. The sealing member thus formed is provided mainly for the purpose of protecting the LED chip from the external environment. As a material for the sealing member, it is preferable to adopt a material that is transparent to the light of the LED chip and is excellent in durability, weather resistance, and the like. For example, an appropriate material can be selected from silicone (including silicone resin, silicone rubber, and silicone elastomer), epoxy resin, urea resin, glass and the like in relation to the emission wavelength of the LED chip. When the light of the LED chip contains light in a short wavelength region, ultraviolet degradation is a problem. Therefore, it is preferable to employ a material having high resistance to ultraviolet degradation such as silicone.
As the material of the sealing member, an appropriate material is adopted in consideration of the light transmittance of the LED chip, the hardness in the cured state, the ease of handling, and the like.

  A phosphor can also be contained in the sealing member. By using the phosphor, part of the light from the LED chip can be converted into light having a different wavelength, and the emission color of the light emitting device can be changed or corrected. Any phosphor can be used as long as it can be excited by light from the LED chip, and the light emission color, durability, and the like of the light emitting device are considered in the selection. The phosphor may be uniformly dispersed in the sealing member or may be localized in a part of the region. For example, by localizing the phosphor in the vicinity of the LED chip, the light emitted from the LED chip can be efficiently irradiated onto the phosphor.

A plurality of types of phosphors can be combined and contained in the sealing member. In this case, a phosphor that emits light when excited by light from the LED chip can be used in combination with a phosphor that emits light when excited by light from the phosphor.
A light diffusing material can be contained in the sealing member to promote the diffusion of light within the sealing member, thereby reducing light emission unevenness. In particular, in the configuration using a phosphor as described above, such a light diffusing material is used in order to promote the color mixture of the light from the LED chip and the light from the phosphor and reduce the unevenness of the emission color. preferable.

(heatsink)
In the LED light emitting device of the present invention, efficient heat dissipation is achieved by using a heat conductive frame, but a heat sink can be used in combination for the purpose of further improving heat dissipation. The heat sink is connected to the thermally conductive frame. Specifically, for example, a heat sink is installed so as to contact the back surface of the exposed portion of the thermally conductive frame. In the configuration including the heat sink, a part of the heat from the LED chip propagates to the heat sink through the thermally conductive frame. As a result, in addition to the heat dissipation action in the heat conductive frame, an efficient heat dissipation action is also achieved in the heat sink, and the LED light emitting device having extremely excellent heat dissipation characteristics is obtained.
The heat sink is required to have a high thermal conductivity. For example, the material is copper or aluminum.

(LED array)
In one form of the present invention, a plurality of LED light emitting devices are linearly arranged to constitute an LED array. Connection between adjacent LED light-emitting devices is made by a thermally conductive frame built in the LED light-emitting device. For example, the LED light-emitting device may be formed at a predetermined interval with respect to the substantially linear thermal conductive frame except for the mounting region (that is, reflector formation, LED mounting, wire bonding, etc. are performed). By doing so, an LED array in which adjacent LED light emitting devices are connected in a seamless state via the exposed portion of the thermally conductive frame is configured. The distance between adjacent LED light emitting devices (the interval between the LED light emitting devices) can be set in consideration of the luminance of each LED light emitting device, the luminance required for the LED array, and the like. Typically, the intervals of the LED light emitting devices are all the same, but some or all of the intervals can be designed as necessary.

One form of the LED array of the present invention adopts a continuous terminal structure. That is, one lead frame (cathode side or anode side) of each LED light-emitting device is connected to one lead frame (anode side or cathode side) of an adjacent LED light-emitting device, whereby all of the LED arrays are included in the LED array. LED light emitting devices are connected in series. Since the LED array having such a structure can be handled as a single component, it is not necessary to individually mount the LED light emitting devices included in the LED array, thereby saving the mounting effort.
Hereinafter, the present invention will be described in more detail with reference to examples.

The LED light-emitting device 1 of the Example of this invention is shown in FIGS. 1 is a perspective view of the LED light emitting device 1, FIG. 2 is a plan view thereof, FIG. 3 is a left side view thereof, and FIG. 4 is a cross-sectional view taken along the line AA of FIG.
The LED light emitting device 1 roughly includes an LED chip 10, a thermally conductive frame 20, a pair of lead frames 30 and 31, and a reflector (package) 40.
As shown in FIG. 5, the LED chip 10 has a configuration in which a plurality of semiconductor layers are stacked on a sapphire substrate 11, and has a main emission peak wavelength in the vicinity of 460 nm. The specifications of each layer of the LED chip 10 are as follows.
Layer: Composition p-type layer 15: p-GaN: Mg
Layer 14 including light emitting layer: n-type layer including InGaN layer 13: n-GaN: Si
Buffer layer 12: AlN
Substrate 11: Sapphire

An n-type layer 13 made of GaN doped with Si as an n-type impurity is formed on the substrate 11 via a buffer layer 12. Here, sapphire is used as the substrate 11, but the substrate 11 is not limited to this. Sapphire, spinel, silicon carbide, zinc oxide, magnesium oxide, manganese oxide, zirconium boride, group III nitride compound semiconductor single crystal Etc. can be used. Furthermore, the buffer layer 12 is formed by MOCVD using AlN, but is not limited to this, and GaN, InN, AlGaN, InGaN, AlInGaN, etc. can be used as the material, and the molecular beam crystal can be used as the manufacturing method. A growth method (MBE method), a halide vapor phase epitaxy method (HVPE method), a sputtering method, an ion plating method, an electron shower method, or the like can be used. When a group III nitride compound semiconductor is used as the substrate, the buffer layer can be omitted.
Further, the substrate and the buffer layer can be removed as necessary after the semiconductor element is formed.
Here, the n-type layer 13 is formed of GaN, but AlGaN, InGaN, or AlInGaN can be used.
In addition, although the n-type layer 13 is doped with Si as an n-type impurity, Ge, Se, Te, C, or the like can also be used as the n-type impurity.
The layer 14 including the light emitting layer may include a quantum well structure (multiple quantum well structure or single quantum well structure), and the light emitting element has a single hetero type, a double hetero type, and a homojunction. It may be of a type.

The layer 14 including the light emitting layer may include a group III nitride compound semiconductor layer having a wide band gap doped with Mg or the like on the p-type layer 15 side. This is to effectively prevent the electrons injected into the layer 15 including the light emitting layer from diffusing into the p-type layer 15.
A p-type layer 15 made of GaN doped with Mg as a p-type impurity is formed on the layer 14 including the light-emitting layer. The p-type layer 15 can be AlGaN, InGaN, or InAlGaN, and Zn, Be, Ca, Sr, and Ba can be used as the p-type impurity. After introducing the p-type impurity, the resistance can be lowered by a known method such as electron beam irradiation, heating in a furnace, or plasma irradiation.
In the light emitting device having the above-described configuration, each group III nitride compound semiconductor layer is formed by performing MOCVD under general conditions, a molecular beam crystal growth method (MBE method), a halide vapor phase epitaxy method (HVPE method). ), A sputtering method, an ion plating method, an electron shower method, or the like.

The n-electrode 18 is composed of two layers of Al and V. After the p-type layer 15 is formed, the p-type layer 15, the layer 14 including the light emitting layer, and a part of the n-type layer 13 are removed by etching. It is formed by vapor deposition on the exposed n-type layer 13.
The translucent electrode 16 is a thin film containing gold and is stacked on the p-type layer 15. The p-electrode 17 is also made of a material containing gold, and is formed on the translucent electrode 16 by vapor deposition. After forming each layer and each electrode by the above process, the separation process of each chip is performed.
A reflective layer made of Al, Ag, titanium nitride, hafnium nitride, zirconium nitride, tantalum nitride, or the like may be formed on the back surface of the substrate 11 (the surface on which the semiconductor layer is not formed). By providing the reflective layer, the light directed toward the substrate 11 can be efficiently reflected and converted in the extraction direction, and the light extraction efficiency can be improved. Such a reflective layer can be formed by a known method such as vapor deposition of a forming material.

Both the heat conductive frame 20 and the lead frames 30 and 31 are made of a copper (Cu) alloy. A part of the thermally conductive frame 20 is covered with the reflector 40 (embedded in the reflector 40). The LED chip 10 is mounted on the central region (LED chip mounting portion 22) of the thermally conductive frame 20. On the other hand, the thermally conductive frame 20 is exposed from the reflector 40 on both the left and right sides. Each exposed portion is bent along the lead frames 30 and 31 (in parallel) after being bent toward the back side of the LED light emitting device 1. In the LED light emitting device 1, this extended portion functions as the mounting area 21. The back surface of each mounting region 21 is located on substantially the same plane as the back surface of the reflector 40. A protrusion 21 a is provided at the tip of each mounting area 21. The heat conductive frame 20 has a uniform thickness (about 0.4 mm) as a whole.
In this embodiment, the total surface area of the exposed portion of the thermally conductive frame 20 is about 4/5 of the entire surface area of the thermally conductive frame 20. By enlarging the exposed portion in this way, efficient heat dissipation through the exposed portion becomes possible. The size of the exposed portion can be set in consideration of heat dissipation efficiency, the size of the LED light emitting device 1, the amount of heat generated by the LED chip 10, and the like. For example, the exposed portion can be designed such that the total surface area of the exposed portion is about 1/2 to about 29/30 of the total surface area of the thermally conductive frame 20.

Each of the lead frames 30 and 31 is partially covered by the reflector 40 (embedded in the reflector 40). Wire bonding is performed as will be described later using a region not covered by the reflector 40 at the end. On the other hand, the exposed portions (lead legs) of the lead frames 30 and 31 are substantially linear and have a length of about 15 mm.
The extension direction (longitudinal axis direction) of the lead frames 30 and 31 and the optical axis of the LED chip 10 are substantially perpendicular.

The reflector 40 is made of a white resin, and is shaped so that the inner peripheral surface forming the cup-shaped portion 41 is at a desired angle with respect to the optical axis of the LED chip 10. As a result, a cup-shaped reflecting surface 42 is formed. Note that the reflectivity of the reflector 40 may be enhanced by, for example, plating the surface of the reflector 40.
The cup-shaped portion 41 is filled with a sealing resin 43 (see FIG. 4). In this embodiment, an epoxy resin in which a yellow phosphor is dispersed is used as the material of the sealing resin 43.

  Next, a method for manufacturing the LED light emitting device 1 will be described. First, the LED chip 10 is prepared by the above method. On the other hand, after a metal plate made of a copper alloy is plated, it is punched to obtain the heat conductive frame 20 and the lead frames 30 and 31. The thermally conductive frame 20 and the lead frames 30 and 31 are in a connected state. Next, a white resin is molded on the heat conductive frame 20 and the lead frames 30 and 31 by injection molding to form the reflector 40. Thereafter, the LED chip 10 is mounted on the LED chip mounting portion 22 of the thermally conductive frame 20 using a conductive paste. Subsequently, each electrode of the LED chip 10 is wire-bonded to the corresponding lead frames 30 and 31 with gold wires. Next, the connecting portions of the heat conductive frame 20 and the lead frames 30 and 31 are removed by punching, and a part of the heat conductive frame 20 is bent and formed by pressing. Finally, the cup-shaped portion 41 of the reflector 40 is molded with a phosphor-containing epoxy resin.

Then, the light emission aspect of the LED light-emitting device 1 is demonstrated. First, blue light is emitted from the LED chip 10 upon receiving power. Part of the blue light excites the phosphor in the process of passing through the sealing resin 43 in the cup-shaped portion 41 of the reflector 40, thereby generating yellowish fluorescence. As a result, the LED light-emitting device 1 emits white light that is a mixed color of blue light and yellow light.
Here, the LED chip 10 generates heat as the LED light emitting device 1 is driven. Part of the heat generated from the LED chip 10 propagates from the bottom surface side of the LED chip 10 to the heat conductive frame 20 through the conductive paste. The heat propagated to the thermally conductive frame 20 spreads from the region immediately below the LED chip 10 to the surroundings, and part of the heat reaches the exposed portion of the thermally conductive frame 20. The heat that reaches the exposed portion is dissipated through the surface into the surrounding air. As described above, in the LED light emitting device 1, a positive heat dissipation action is exerted by a part (exposed portion) of the heat conductive frame 20 provided in the package. Moreover, since the exposed portion having a large surface area is provided as described above, a high heat dissipation effect is exhibited.
As described above, in the LED light emitting device 1, the heat of the LED chip 10 is efficiently dissipated by using the heat conductive frame 20 provided in the package as a main heat dissipation path, and as a result, the temperature rise of the LED chip 10 is increased. Alleviated. As a result, an LED light emitting device having excellent driving stability or reliability is achieved, and at the same time, a long life is achieved. In addition, as a result of improving the heat dissipation characteristics, it is possible to cope with LED chips with high output. Furthermore, a simple and small device can be obtained by incorporating a heat dissipation member in the package.

Here, the usage mode (mounting mode) of the LED light emitting device 1 will be described by taking as an example a case where a planar light source device (specifically, for example, a backlight device of a liquid crystal display) is configured. FIG. 6 is a perspective view of this example, and FIG. 7 shows a state observed from the lateral direction.
As shown in FIG. 6, a plurality of LED light emitting devices 1 are mounted on a wiring board 50 in a line. Each LED light-emitting device 1 is mounted on the wiring board 50 using the lead frames 30 and 31 and the tips 21a of the mounting regions 21 provided on the left and right sides of the thermal conductive frame 20. Thus, when the LED light emitting device 1 is mounted, it is also soldered at the tip 21a of the heat conductive frame 20. As a result, the LED light emitting device 1 is fixed to the wiring board 50 at a total of four locations. In addition, the lead frames 30 and 31 are fixed to the wiring board 50 at positions offset from the tip positions of the lead frames 30 and 31 (see FIG. 7) and in a positional relationship across the lead frames 30 and 31. Since it becomes the above mounting aspects, the LED light-emitting device 1 can be mounted on the wiring board 50 with a very stable posture. As a result, high mounting reliability is obtained and mounting accuracy is improved.
On the other hand, when the protrusion 21 a formed in the mounting region 21 of the thermally conductive frame 20 is inserted into the hole of the wiring substrate 50, the end surface 21 b of the mounting region 21 is locked to the upper surface of the wiring substrate 50. With such a configuration, the LED light emitting device 1 can be easily positioned and can be more reliably fixed.
Fixing of the lead frames 30 and 31 and fixing of the mounting region 21 of the heat conductive frame 20 can be simultaneously performed by soldering. Thus, an additional process is not required to fix the heat conductive frame 20, and efficient mounting is possible.
The diameter of the protrusion 21a formed in the mounting region 21 of the heat conductive frame 20 is designed to match the hole diameter of a general-purpose substrate. As a result, not only a dedicated wiring board but also a general-purpose wiring board can be used.

  A light guide plate 51 is installed above the wiring substrate 50 on which each LED light emitting device 1 is mounted so that the end surface 52 faces the light emitting side of the LED light emitting device 1. The light guide plate 51 is disposed in a position substantially parallel to the wiring board 50. In the LED light emitting device 1, the light emitting direction of the LED chip 10 is substantially perpendicular to the wiring board 50 because the light emitting direction of the LED chips 10 is substantially perpendicular to the legs (lead feet) of the lead frames 30 and 31. If 1 is mounted, the light emission direction of the LED chip 10 is substantially parallel to the wiring board 50. As a result, the light guide plate 51 can be disposed in the positional relationship as described above, and the overall configuration is small. Such a configuration is particularly effective when a sufficient space cannot be secured in front of the end surface 52 (light introduction surface) of the light guide plate 51.

Here, for the purpose of improving the heat dissipation effect by the heat conductive frame 20, the exposed portion (mounting region) of the heat conductive frame can be formed into a shape as shown in FIG.
In the example of FIG. 8A, the mounting region 22 of the heat conductive frame includes a plurality of fins 23. The plurality of fins 23 are aligned in a line at equal intervals. Moreover, the through-hole 24 exists between each fin, respectively. A heat conductive frame provided with such a mounting region 22 can be manufactured by the following procedure. First, after cutting a metal plate made of a copper alloy, it is formed by punching in a U-shape at the position where the fins 23 are formed, and then bending and erecting the portion surrounded by the punched portion at its base. When the heat conductive frame of this example is used, the heat from the LED chip propagates to the mounting region 22 and is dissipated there, but by providing a plurality of fins 23, a heat dissipation effect due to the air flow between the fins is expected. it can. In addition, since air can pass through the through holes 24 formed between the fins, the movement of air in the vicinity of each fin surface is promoted, and high heat dissipation efficiency is obtained. In the heat conductive frame of this example, the edge of the mounting region 22 functions as a heat pipe, and heat is propagated in the tip direction.

  In the example of FIG. 8B, a plurality of fin-like protrusions 26 are formed in the mounting region 25 of the thermally conductive frame. The heat conductive frame having such a shape can be manufactured by cutting a deformed rolled sheet into a desired shape. Or it can also produce using press work. In the heat conductive frame of this example, a plurality of protrusions are formed in the mounting region 25 to increase the surface area of the mounting region, and the shape of the protrusions is finned to efficiently dissipate heat by airflow. By doing so, a very high heat dissipation effect is exhibited.

Another embodiment of the present invention is shown in FIG. FIG. 9 is a perspective view of the LED array 2. For convenience of explanation, the same members as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.
The LED array 2 has a configuration in which a plurality of LED light emitting devices 60 are linearly connected at equal intervals. Each LED light emitting device 60 is connected by a heat conductive frame 27. In other words, the LED light-emitting devices 60 are formed at three locations of the heat conductive frame 27, and the adjacent LED light-emitting devices 60 are connected to each other through the exposed portion 27a of the heat conductive frame 27 in a seamless state. LED array. The mounting regions 21 are formed on the left and right ends of the heat conductive frame 27. Except for the heat conductive frame 27, the configuration of each LED light emitting device 60 is the same as that of the LED light emitting device 1 of the above embodiment.
The LED array 2 having the above configuration is a light source device in which a plurality of light emitting points are arranged in a straight line. Such a light source device can be suitably used as a light source for a backlight such as a liquid crystal display. When the LED array 2 is mounted, the leading ends of the lead frames 30 and 31 of each LED light emitting device 60 and the leading end 21a of the mounting region 21 of the heat conductive frame 27 are fixed to the wiring board. As a result, the LED array 2 can be mounted on the wiring board in a very stable posture, and the mounting reliability and mounting accuracy are improved.
Here, in the LED array 2, the mounting regions 21 are provided only at the left and right ends of the thermally conductive frame 27. However, the mounting regions may be similarly provided in the exposed portions 27 a between the adjacent LED light emitting devices 60.

  Next, the LED array 3 which employ | adopted the continuous terminal structure is shown in FIG. In the LED array 3, lead frames are connected between adjacent LED light emitting devices 60 so that the three LED light emitting devices 60 are connected in series. Specifically, the cathode side of the left LED light emitting device 60 is connected to the anode side of the central LED light emitting device 60 by the lead frame 33, and similarly the cathode side of the central LED light emitting device 60 is connected to the right end LED by the lead frame 34. It is connected to the anode side of the device 60. The LED array 3 having a continuous terminal structure can be handled as a single component. Therefore, in the LED array 3, it is not necessary to solder each LED light emitting device 60 individually when mounting the LED array 3, and the mounting labor can be saved.

FIG. 11 shows an LED array 4 having a heat sink. In the LED array 4, the thermally conductive frame 28 that connects the LED light emitting devices 60 is connected to the heat sink 54 at the exposed portion (the connecting portion 28 a and the mounting region 21). The heat sink 54 is required to have a large heat capacity. For example, the material is copper or aluminum. The heat conductive frame 28 and the heat sink 54 can be connected by, for example, screwing.
In the LED array 4 having the above configuration, a part of the heat from the LED chip propagated to the thermally conductive frame 28 is transferred to the heat sink 54. Accordingly, heat from the LED chip is dissipated by the exposed portion of the heat conductive frame 28 and the heat sink 54. As a result, further improvement in heat dissipation can be achieved.

In the LED arrays 2 to 4, three LED light emitting devices 60 are connected, but the number of LED light emitting devices is not limited to this. That is, an LED array can be configured using any number of LED light emitting devices.
In the LED arrays 2 to 4, the LED light-emitting devices 60 are arranged in a straight line. However, by appropriately changing the shape of the thermally conductive frame connecting the LED light-emitting devices 60, a curved shape, a zigzag shape, and a pulse shape Various arrangement modes can be realized.
Moreover, although LED light-emitting device 60 was arrange | positioned at equal intervals in LED arrays 2-4, an arrangement | positioning aspect is not restricted to this, You may provide a difference in the distance between adjacent LED light-emitting devices.

  The LED light-emitting device (or LED array) of the present invention can be suitably used as a light source for backlights of liquid crystal displays such as mobile phones, personal digital assistants, car navigation systems, laptop (notebook) PCs, and liquid crystal televisions. . When used as a light source for backlight, a light guide plate is usually used together, and light of the LED light emitting device (or LED array) of the present invention is converted into planar light by the light guide. However, the use of the LED light-emitting device (or LED array) of the present invention is not limited to the use of a light guide plate in combination, and the present invention can also be applied to a use in which the light is directly used for illumination light, for example.

  The present invention is not limited to the description of the embodiments and examples of the invention described above. Various modifications may be included in the present invention as long as those skilled in the art can easily conceive without departing from the description of the scope of claims.

It is a perspective view of the LED light-emitting device 1 which is an Example of this invention. 1 is a plan view of an LED light emitting device 1. FIG. 2 is a left side view of the LED light emitting device 1. FIG. It is sectional drawing in the AA line position of FIG. It is a figure which shows the structure of the LED chip 10 used for the LED light-emitting device 1. FIG. 1 is a perspective view of a planar light source device using an LED light emitting device 1. FIG. It is the figure which looked at the planar light source device using the LED light-emitting device 1 from the horizontal direction. It is an example of the shape of the mounting area | region of a heat conductive flame | frame. (a) is a shape in which a plurality of fins 23 are formed, and (b) is a shape in which fin-like projections 26 are formed. It is a perspective view of the LED array 2 which is the other Example of this invention. It is a perspective view of LED array 3 of a connection terminal structure. It is a perspective view of LED array 4 provided with the heat sink. It is sectional drawing which shows the structural example of the backlight light source device which uses the conventional LED lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,60 LED light-emitting device 10 LED chip 20, 27, 28 Thermal conductive frame 21, 22, 25 Mounting area 23 of a thermal conductive frame Radiation fin 26 Fin-shaped projection part 40 Reflector 41 Reflector cup-shaped part 42 Reflecting surface 50, 102 Wiring boards 51, 103 Light guide plate 100 Cannonball type LED
101 Cannonball type LED100 lead leg

Claims (7)

An LED chip;
A thermally conductive frame on which the LED chip is mounted;
A pair of lead frames to which the electrodes of the LED chip are connected;
A reflector that covers a part of the thermally conductive frame and a part of the lead frame and forms a cup-shaped reflective surface around the LED chip;
The light emitting direction of the LED chip is substantially perpendicular to the extending direction of the lead frame;
The exposed portion of the thermally conductive frame is a region extending along the extension direction of the lead frame, and when the tip of the lead frame is fixed to the wiring substrate, a part of the exposed portion is similarly attached to the wiring substrate. An LED light emitting device comprising a mounting area to be fixed.   2. The LED light emitting device according to claim 1, wherein the thermally conductive frame is exposed on both right and left sides of the reflector, and the mounting region is formed in each exposed portion.   3. The LED light-emitting device according to claim 1, wherein the part of the mounting region is located at a position offset from a tip of the pair of lead frames.   The LED light-emitting device according to claim 1, wherein the mounting region includes a portion that is locked to the wiring board when the part is fixed to the wiring board.   The LED light-emitting device according to claim 1, further comprising a heat sink to which the thermally conductive frame is connected. A plurality of the LED light-emitting devices according to claim 1 are arranged in a straight line,
An LED array in which adjacent LED light-emitting devices are connected in a seamless state via an exposed portion of the thermally conductive frame.   All LED light emitting devices are connected in series by connecting one lead frame (cathode side or anode side) of each LED light emitting device to one lead frame (anode side or cathode side) of an adjacent LED light emitting device. The LED array according to claim 6, wherein:

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