JP4222017B2 - Light emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light emitting device, and more particularly to a light emitting device capable of obtaining uniform light emission with little color unevenness, for example, white light with high output.
[0002]
[Prior art]
Today, high-luminance and high-power semiconductor light-emitting elements and small and favorable light-emitting devices have been developed and used in various fields. Such a light-emitting device is used for, for example, an optical printer head light source, a liquid crystal backlight light source, various meter light sources, various reading sensors, and the like by taking advantage of features such as small size, low power consumption, and light weight.
[0003]
A light-emitting diode (hereinafter also referred to as an LED) which is a light-emitting device is small, efficient, and capable of emitting bright colors. Further, since it is a semiconductor element, it has the characteristics that it has no ball breakage, is excellent in initial drive characteristics and earthquake resistance, and is resistant to repeated ON / OFF lighting. Therefore, it is widely used as various indicators and various light sources. However, since the LED has an excellent monochromatic peak wavelength, it is difficult to emit an emission wavelength such as white.
[0004]
Therefore, in recent years, a light emitting diode has been used in which light emitted from a light emitting element is color-converted by a phosphor and output. This light-emitting diode can emit other light-emitting colors such as white light-emitting elements using one type of light-emitting element.
[0005]
For example, when a white light emitting device is constructed, blue light is emitted from a semiconductor light emitting element, while a fluorescent material that emits yellow light is dispersed in a sealing resin that seals the semiconductor light emitting element. A part of the light emitted from the semiconductor light emitting element is absorbed in the fluorescent material, the wavelength is converted to emit yellow light, and a light emitting diode capable of emitting white mixed light is formed by mixing these blue light and yellow light. (For example, refer to Patent Document 1).
[0006]
[Patent Document 1]
Special Table 2000-512806
[0007]
[Problems to be solved by the invention]
However, significant color variation is observed between the light emitting diodes formed in this way.
[0008]
At present, when white light-emitting diodes are used for indoor displays and lighting, and more strict color tone is required, these color variations are a major problem.
[0009]
On the other hand, although a white light emitting diode that emits very little light under a constant power can be selected to form an LED display or the like, the yield is extremely poor.
[0010]
Accordingly, the present invention provides a light-emitting device that solves the above-described problems, can obtain uniform mixed light with little color unevenness at high output, and has excellent mass productivity with little color variation between light-emitting devices. Is an issue.
[0011]
[Means for Solving the Problems]
A light-emitting device according to the present invention includes a light-emitting element having a pair of positive and negative electrodes on the same surface side and capable of emitting a part of light emission from a side end surface, and absorbing a part of light of the light-emitting element. A light-emitting device having a fluorescent material capable of emitting light having different wavelengths, wherein the light-emitting element has conductive particles with respect to a base surface having an external electrode on the surface. The color conversion layer is laminated on and in contact with the anisotropic conductive layer extending around the light emitting element, and is mounted on the anisotropic conductive layer. The side end face of the element is characterized in that one side in the thickness direction is covered with the anisotropic conductive layer and the other side is covered with the color conversion layer.
[0012]
One of the characteristics of the present invention is that a member that blocks light such as an electrode is not disposed on the light emitting surface side, and a part of the side end surface of the light emitting element is covered with a color conversion layer, and the other part of the side end surface is covered. It is in the point which coat | covers with the anisotropic conductive layer which has electroconductive particle. Accordingly, a part of the light emitted from the electrode forming surface side and the side end surface of the light emitting element is guided to the anisotropic conductive layer disposed on the bottom surface side of the color conversion layer, and the guided light is guided to the different light. It is reflected and scattered by the conductive particles in the isotropic conductive layer, and can be efficiently taken out to the upper color conversion layer. Thereby, the excitation light can be irradiated to the bottom surface side of the color conversion layer that has not been effectively used until now, and the conversion efficiency of the fluorescent substance can be dramatically increased.
[0013]
The color conversion layer has a shape that rises vertically with a substantially uniform thickness from the top surface of the anisotropic conductive layer, and the fluorescent material is 30 parts by weight with respect to 100 parts by weight of the translucent member. It is characterized by containing ~ 100 parts by weight. In this way, the fluorescent material is not placed above the light emitting element, and the fluorescent material content of the color conversion layer placed only on the side end face side is emitted from the fluorescent material. By adjusting so that only the emitted light is obtained, the monochromatic light of the light emitting element itself and the monochromatic light emitted from the color conversion layer can be extracted with high output, respectively. In this manner, by setting the fluorescent material at a constant location, a light-emitting device capable of emitting light with high output without color variation between the light-emitting devices can be obtained with high yield.
[0014]
Further, the color conversion layer has substantially the same thickness as the light emitting element, and has a diffusion layer that is continuous with and in contact with the exposed surface of the light emitting element and the exposed surface of the color conversion layer. Thereby, the color mixing property of the light each emitted from a light emitting element and a fluorescent substance can be improved.
[0015]
Further, a plurality of the light emitting elements are mounted with the color conversion layer interposed therebetween. Specifically, the light emitting device is an integrated optical device in which a plurality of light emitting elements are placed on a base surface having external electrodes with a certain space, and the space is sealed with the color conversion layer. In the present invention, an anisotropic conductive layer that is also an electrical connection means is used as a member that guides part of light from the light emitting element to the bottom surface side of the color conversion layer. A large number of electrodes on the surface side can be connected with high reliability at a time, and many miniaturized light emitting elements can be mounted with high reliability and high density. As a result, an integrated light emitting device having further excellent color mixing can be obtained.
[0016]
As the light-emitting element, an array light-emitting element having a plurality of light-emitting layers, that is, an array light-emitting element having a plurality of positive and negative pairs on the same surface side can also be used. As described above, in the present invention, the anisotropic conductive layer can be said to be an excellent member for improving optical characteristics, reliability, optical characteristics, and productivity in a color conversion light emitting device.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
As a result of various experiments, the present inventor has improved the luminous intensity of the light-emitting device by guiding the light emitted from the light-emitting element to the maximum in the light-emitting device using the fluorescent material, The present inventors have found that it is possible to improve color variation and color unevenness between light emitting devices.
[0018]
The color conversion type light emitting device emits monochromatic light from a semiconductor light emitting element, while absorbing a part of the monochromatic light in a sealing resin for sealing the semiconductor light emitting element and emitting light having a different wavelength. The mainstream method is to disperse possible fluorescent substances and obtain a desired color tone by mixing these lights.
[0019]
However, the specific gravity of the fluorescent material reaches several times that of the liquid resin, and the viscosity of the thermosetting resin is greatly reduced after heat curing. Therefore, the light-emitting element is covered with the liquid resin containing the fluorescent material and heat-cured. In this case, most of the fluorescent substances in the resin are concentrated and settled around the light emitting element. The fluorescent materials that have gathered and settled form a certain volume and settle around the light emitting element. For this reason, it is considered that the most efficient absorption of light from the light emitting element is actually only the fluorescent substance located on the outermost surface around the light emitting element, and most other fluorescent substances cannot perform their original functions and simply It is an obstacle that causes a decrease in light energy.
[0020]
On the other hand, many methods have been proposed in which a light emitting element is electrically connected in a package having a pair of positive and negative electrodes on the bottom surface of the recess, and a fluorescent material is coated on the inner side surface of the package (Japanese Patent Laid-Open No. 10-112557). No., JP-A-11-274572, etc.). Although light emitted from the upper surface of the light emitting element is efficiently extracted by this method, light emitted from the side end face of the light emitting element has not been sufficiently utilized.
[0021]
Therefore, the present invention efficiently irradiates all the fluorescent materials with excitation light from the light emitting element, and further determines the place where the fluorescent material is placed, so that the color conversion type has high brightness and little color variation between the light emitting devices. A light emitting device is realized.
[0022]
Hereinafter, the present invention will be described in detail based on specific examples shown in the drawings. FIG. 1 is a schematic cross-sectional view of an SMD type light emitting diode which is an embodiment of the present invention. Using the package 1 having a recess and insert-molded so that the surfaces of the pair of lead electrodes 2 and 3 are exposed from the bottom surface of the recess, the bottom surface of the recess and the electrode forming surface side of the light emitting element 5 are opposed to each other. The anisotropic conductive layer 4 is interposed between and electrically connected to the opposing surfaces. The anisotropic conductive layer 4 is continuously formed on the entire bottom surface of the recess. The anisotropic conductive layer contains conductive particles 4a that can efficiently reflect light emitted from the light emitting element and have conductivity. The light-emitting element 5 is formed on a sapphire substrate through a buffer layer made of gallium nitride with a nitride semiconductor (Al _x Ga _y In _z N, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, and X + Y + Z = 1) are formed. The anisotropic conductive layer 4 extends around the light emitting element, and is in contact with the surface of the anisotropic conductive layer 4 to absorb a part of light from the light emitting element and emit light of different wavelengths. A color conversion layer 6 having a fluorescent material that can be used is provided. Further, the side end face of the light emitting element is covered with the anisotropic conductive layer 4 at the lower part which is the base face side in the thickness direction, and the other upper part is covered with the color conversion layer 6. . Further, the surface of the light emitting element 5 and the surface of the color conversion layer 6 are substantially parallel, and a continuous diffusion layer is provided in contact with these surfaces. Hereafter, each structure of the light-emitting device which is embodiment of this invention is explained in full detail.
[Light emitting element 5]
In the present invention, the light-emitting element 5 is not particularly limited as long as it has a pair of positive and negative electrodes on the same surface side and can emit a part of the light emission from the side end surface. It is preferable to use a semiconductor light emitting element having a light emitting layer capable of emitting light. Examples of such semiconductor light emitting devices include various semiconductors such as ZnSe and GaN, but nitride semiconductors (In that are capable of emitting short wavelengths that can excite fluorescent materials efficiently). _X Al _Y Ga _1-XY N, 0 ≦ X, 0 ≦ Y, and X + Y ≦ 1) are preferable. Examples of the semiconductor structure include a homostructure having a MIS junction, a PIN junction, and a pn junction, a heterostructure, or 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.
[0023]
When a nitride semiconductor is used, a material such as sapphire, spinel, SiC, Si, ZnO or the like is 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 of GaN, AlN, GaAIN or the like is formed on the sapphire substrate, and a nitride semiconductor having a pn junction is formed thereon.
[0024]
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.
[0025]
When white light is emitted in the light emitting diode of the present invention, the emission wavelength of the light emitting element is preferably 400 nm or more and 530 nm or less, taking into consideration the complementary color relationship with the emission wavelength from the fluorescent material, deterioration of the translucent resin, and the like. More preferably, it is 490 nm or less. 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. Note that when a transparent material that is a component of the fluorescent material of the color conversion layer, the diffusion layer, and the anisotropic conductive layer is made of a resin that is relatively difficult to be deteriorated by ultraviolet rays, glass that is an inorganic material, etc., it is shorter than 400 nm. A light emitting element having a main light emission wavelength in the ultraviolet region or the short wavelength region of visible light can also be used. Color conversion type light-emitting devices that use light-emitting elements having wavelengths in the ultraviolet region are compared with the case of using semiconductor light-emitting elements that emit visible light because the chromaticity is determined only by the emission color converted by the fluorescent material. Thus, variations such as the wavelength of the semiconductor light emitting element can be absorbed, and the mass productivity can be improved.
[Anisotropic conductive layer 4]
In the present embodiment, the light-emitting element is placed such that the electrode forming surface side on which a pair of positive and negative electrodes is provided faces the external electrode exposed from the bottom surface of the package recess, and the continuous anisotropic conductive layer 4 Flip chip mounted through.
[0026]
In the present invention, the anisotropic conductive layer 4 includes conductive particles that can efficiently reflect light from the light-emitting element in a material made of organic or inorganic material having thermoplasticity or thermosetting property. Is distributed. As a material made of an organic material having thermoplasticity or thermosetting property, for example, a transparent resin such as an epoxy resin, an acrylic resin, or silicone is preferably used. Specific examples of the conductive particles include Ni particles, and particles having a metal coat made of Ni, Au, or the like on the surface of particles such as plastic and silica. In the present invention, the content of the conductive particles is preferably 0.3 vol% or more and 1.2 vol% or less with respect to the adhesive, and such an anisotropic conductive layer is formed by heating and pressurizing when the light emitting element is mounted. High conductivity can be easily obtained between the thickness directions of the layers. On the other hand, since the filling amount of the conductive particles is small in the plane direction of the layer, a short circuit between adjacent electrodes due to contact between the conductive particles does not occur, and high insulation can be maintained. More preferably, 1 mm in the anisotropic conductive layer ² When the number of particles is 3500 or more and 5000 or less, a small light-emitting element having a narrow pitch between the electrodes can be finely connected to the external electrode on the base surface with high reliability. Furthermore, the anisotropic conductive layer can efficiently reflect and scatter light from the light emitting element to the upper color conversion layer.
[0027]
In the present invention, the anisotropic conductive layer 4 seals between the light emitting element surface and the base surface facing each other and directly covers a part of the side end face of the light emitting element. As a result, part of the light emitted from the light emitting element is taken into the anisotropic conductive layer, reflected and scattered by the conductive particles in the anisotropic conductive layer, and the fluorescent material in the color conversion layer is irradiated from below. can do. In the conventional light emitting device, only the fluorescent substance adjacent to the light emitting element or the fluorescent substance existing on the outermost surface is efficiently excited, and the fluorescent substance buried under the other cannot sufficiently perform the original function. It was. However, in the present invention, a part of the light emitted from the end face of the light emitting element is irradiated over the entire surface from the lower side of the conversion layer, so that the color conversion layer is the uppermost surface, the side surface adjacent to the light emitting element, and the anisotropic surface. Since excitation light is irradiated from the lower side in contact with the conductive film, color conversion efficiency can be improved in most fluorescent materials. Further, even when the light converted by the color conversion layer is reflected in the base surface direction, the path can be quickly changed by the conductive particles in the anisotropic conductive layer and extracted upward.
[Color conversion layer 6]
In the light emitting device of the present invention, the anisotropic conductive layer extends to the end of the base surface, and a color conversion layer is provided in contact with the upper surface of the extending portion of the anisotropic conductive layer and the side end surface of the light emitting element. It has been. With this configuration, the color conversion layer is irradiated with excitation light from the side end face of the adjacent light emitting element, and absorbs light from the light emitting element from below through the anisotropic conductive film. Can do. Accordingly, since the color conversion layer can absorb excitation light from the entire surface, a light emitting device capable of emitting light with high luminance with a minimum amount of fluorescent material can be obtained.
[0028]
In the present embodiment, the color conversion layer contains a fluorescent material capable of absorbing a part of the light of the light emitting element and emitting light of different wavelengths in the light transmitting member. As the translucent member, either an organic substance or an inorganic substance can be used depending on the characteristics and application of the light emitting element to be used. As a specific material of the translucent member suitably used in the present invention, a transparent resin excellent in weather resistance such as an epoxy resin, an acrylic resin, or silicone, or glass is preferably used. Here, by including the same material as the material contained in the anisotropic conductive layer as the material of the color conversion layer, the adhesion between the anisotropic conductive layer and the color conversion layer is improved, and the peeling of both is prevented. Can do. Moreover, you may contain a pigment with the said fluorescent substance.
[0029]
In addition, the color conversion layer has a shape that rises vertically from the anisotropic conductive layer with a substantially uniform thickness, and the content of the fluorescent material is 100 parts by weight or more and 200 parts by weight with respect to 100 parts by weight of the translucent member. With the following, a light-emitting device that can emit light with high output can be obtained with high productivity.
[0030]
When a light-emitting element capable of emitting ultraviolet light having a main light emission peak in a short wavelength region near 400 nm is used as the light-emitting element, the color conversion layer absorbs visible light by absorbing the ultraviolet light with a resin or glass that is relatively resistant to ultraviolet light. It is preferable to use a fluorescent material that can emit light. Fluorescent substances that can fluoresce into red, blue, and green with such short-wavelength light, such as Y as a red phosphor ₂ O ₂ S: Eu, Sr as blue phosphor ₅ (PO ₄ ) ₃ Cl: Eu, and (SrEu) O.Al as a green phosphor ₂ O ₃ Can be contained in the ultraviolet resistant resin and disposed as a color conversion thin film layer on the side end face of the light emitting element emitting short wavelength light, whereby white light can be obtained. When using a light emitting element that emits short wavelength light in this manner, the substrate side of the light emitting element is opaque, and the anisotropic conductive layer and the diffusion layer are a resin that is relatively resistant to ultraviolet rays, like the color conversion layer. It is preferable to use glass or glass as the main agent. In addition to the phosphors described above, 3.5MgO · 0.5MgF as a red phosphor ₂ ・ GeO ₂ : Mn, Mg ₆ As ₂ O ₁₁ : Mn, Gd ₂ O ₂ : Eu, LaO ₂ S: Eu, Re as blue phosphor ₁₀ (PO ₄ ) ₆ Q ₂ : Eu, Re ₁₀ (PO ₄ ) ₆ Q ₂ : Eu, Mn (where Re is at least one selected from Sr, Ca, Ba, Mg, Zn, Q is at least one selected from halogen elements F, Cl, Br, I), BaMg ₂ Al ₁₆ O ₂₇ : Eu etc. can be used suitably. By using these fluorescent materials, a white light emitting diode capable of emitting light with high luminance can be obtained.
[0031]
In the color conversion thin film layer, when these different kinds of fluorescent materials are mixed and arranged as a single color conversion thin film layer, it is preferable that the center particle diameters and shapes of various fluorescent materials are similar. As a result, light emitted from various fluorescent materials can be mixed well and color unevenness can be suppressed. Moreover, you may laminate | stack each fluorescent substance as each color conversion thin film layer. When the color conversion thin film layers of various fluorescent materials are arranged as multiple thin film layers, the red fluorescent material layer, the green fluorescent material layer, and the blue fluorescent material layer are sequentially stacked in consideration of the ultraviolet light transmittance of each fluorescent material. It is preferable to make it. In the color conversion multiple thin film layer, when the central particle size of each fluorescent material is set to blue fluorescent material> green fluorescent material> red fluorescent material so that the particle size of the fluorescent material in each layer decreases from the lower layer to the upper layer, Ultraviolet light can be transmitted through the fluorescent material well up to the upper layer and converted to visible light, and ultraviolet light leakage can be prevented. In addition, each color conversion layer can be arranged on the element so as to have a stripe shape, a lattice shape, or a triangle shape. In this way, it is preferable that the layers are arranged with a space between them to improve the color mixing property.
[Fluorescent substance]
The particle size of the large particle size fluorescent material used in the present invention is preferably in the range of the center particle size of 6 μm to 50 μm, more preferably 15 μm to 30 μm. The fluorescent material having such a particle size has a light absorption rate. In addition, the conversion efficiency is high and the width of the excitation wavelength is wide. Fluorescent materials smaller than 6 μm are relatively easy to form aggregates and are densely settled in the liquid resin, thus reducing the light transmission efficiency and excitation with poor light absorption and conversion efficiency. The wavelength range is narrow.
[0032]
Here, in the present invention, the particle size of the fluorescent material is a value obtained by a volume-based particle size distribution curve, and the volume-based particle size distribution curve can be obtained by measuring the particle size distribution of the fluorescent material by a laser diffraction / scattering method. Is. Specifically, in an environment of an air temperature of 25 ° C. and a humidity of 70%, a fluorescent substance is dispersed in a sodium hexametaphosphate aqueous solution having a concentration of 0.05%, and a laser diffraction particle size distribution analyzer (SALD-2000A) It was obtained by measuring in a particle size range of 0.03 μm to 700 μm. In the present invention, the central particle size of the fluorescent material is a particle size value when the integrated value is 50% in the volume-based particle size distribution curve. It is preferable that the fluorescent material having this central particle size value is contained with high frequency, and the frequency value is preferably 20% to 50%. In this way, by using a fluorescent material with small variation in particle diameter, a light emitting device with suppressed color unevenness and good contrast can be obtained.
(Yttrium / aluminum oxide phosphor)
The fluorescent material used in the present embodiment is excited by light emitted from a semiconductor light emitting element having a nitride-based semiconductor as a light emitting layer to emit light, and is activated by cerium (Ce) or praseodymium (Pr). A phosphor based on an aluminum oxide phosphor (YAG phosphor) can be obtained. As a specific yttrium / aluminum oxide fluorescent material, YAlO ₃ : Ce, Y ₃ Al ₅ O ₁₂ : Ce (YAG: Ce) or Y ₄ Al ₂ O ₉ : Ce, and also a mixture thereof. 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.
[0033]
In the present specification, the yttrium / aluminum oxide fluorescent material activated with Ce is to be interpreted in a broad sense, and 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 or both of Ba, Tl, Ga, and In are substituted.
[0034]
More specifically, the general formula (Y _z Gd _1-z ) _Three Al _Five O ₁₂ : Photoluminescence phosphor represented by Ce (where 0 <z ≦ 1) or a general formula (Re _1-a Sm _a ) _Three Re ' _Five O ₁₂ : Ce (where 0 ≦ a <1, 0 ≦ b ≦ 1, Re is at least one selected from Y, Gd, La, Sc, and Re ′ is at least one selected from Al, Ga, In) The photoluminescence phosphor shown in FIG. Since this fluorescent material has a garnet 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.
[0035]
Further, the photoluminescence phosphor can increase the excitation 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-based phosphor having a garnet structure, a part of Al is replaced with Ga to reduce the emission wavelength to a short wavelength side, and a part of Y of the composition is replaced with Gd. Thus, the emission wavelength can be shifted to the long wavelength side.
[0036]
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.
[0037]
Such photoluminescent phosphors use oxides or compounds that easily become oxides at high temperatures as raw materials for Y, Gd, Al, and Ce, Pr, and mix them well in a stoichiometric ratio. And get raw materials. Alternatively, a mixture of a coprecipitated oxide obtained by calcining a solution obtained by coprecipitating a rare earth element of Y, Gd, Ce, and Pr in acid with a stoichiometric ratio with oxalic acid, and aluminum oxide is mixed. A mixed raw material is obtained. An appropriate amount of fluoride such as barium fluoride or ammonium fluoride is mixed as a flux and packed in a crucible, and baked in air at a temperature range of 1350 to 1450 ° C. for 2 to 5 hours to obtain a baked product. Can be obtained by ball milling in water, washing, separating, drying and finally passing through a sieve.
[0038]
In the light emitting diode of the present invention, such a photoluminescent phosphor may be a mixture of yttrium / aluminum / garnet phosphors activated by two or more kinds of cerium and other phosphors. By mixing two types of yttrium / aluminum / garnet phosphors with different amounts of substitution from Y to Gd, light having a desired color tone can be easily realized. In particular, when the fluorescent material with a large amount of substitution is the large particle size fluorescent material and the fluorescent material with the small amount of substitution or zero is the medium particle size fluorescent material, the color rendering property and the luminance can be improved at the same time. Can do.
(Nitride phosphor)
The fluorescent material used in the present invention contains N and at least one element selected from Be, Mg, Ca, Sr, Ba, and Zn, and C, Si, Ge, Sn, Ti, Zr, and Hf. And a nitride-based phosphor activated with at least one element selected from rare earth elements. Further, the nitride-based phosphor used in this embodiment refers to a phosphor that emits light by being absorbed by absorbing light emitted from a light-emitting element, visible light, ultraviolet light, or YAG-based phosphor. In particular, the phosphor according to the present invention includes Sr—Ca—Si—N: Eu, Ca—Si—N: Eu, Sr—Si—N: Eu, and Sr—Ca—Si—O—N with Mn added: Eu, Ca-Si-ON: Eu, Sr-Si-ON: Eu-based silicon nitride. The basic constituent element of this phosphor is represented by the general formula L _X Si _Y N _{(2 / 3X + 4 / 3Y)} : Eu or L _X Si _Y O _Z N _{(2 / 3X + 4 / 3Y-2 / 3Z)} : Eu (L is Sr, Ca, or any one of Sr and Ca). In the general formula, X and Y are preferably X = 2, Y = 5, or X = 1, Y = 7, but any can be used. Specifically, Mn is added as a basic constituent element (Sr _X Ca _1-X ) ₂ Si ₅ N ₈ : Eu, Sr ₂ Si ₅ N ₈ : Eu, Ca ₂ Si ₅ N ₈ : Eu, Sr _X Ca _1-X Si ₇ N ₁₀ : Eu, SrSi ₇ N ₁₀ : Eu, CaSi ₇ N ₁₀ : It is preferable to use a phosphor represented by Eu, but in the composition of this phosphor, from the group consisting of Mg, Sr, Ca, Ba, Zn, B, Al, Cu, Mn, Cr and Ni At least one or more selected may be contained. However, the present invention is not limited to this embodiment and examples.
L is any one of Sr, Ca, Sr and Ca. The mixing ratio of Sr and Ca can be changed as desired.
By using Si for the composition of the phosphor, it is possible to provide an inexpensive phosphor with good crystallinity.
[0039]
Europium Eu, which is a rare earth element, is used for the emission center. Europium mainly has bivalent and trivalent energy levels. The phosphor of the present invention has Eu as a base material for alkaline earth metal silicon nitride. ²⁺ Is used as an activator. Eu ²⁺ Is easily oxidized and trivalent Eu ₂ O ₃ It is marketed with the composition. However, commercially available Eu ₂ O ₃ Then, the involvement of O is large, and it is difficult to obtain a good phosphor. Therefore, Eu ₂ O ₃ It is preferable to use a product obtained by removing O from the system. For example, it is preferable to use europium alone or europium nitride. However, this is not the case when Mn is added.
[0040]
The additive Mn is Eu. ²⁺ Is promoted to improve luminous efficiency such as luminous brightness, energy efficiency, and quantum efficiency. Mn is contained in the raw material, or contains Mn alone or a Mn compound during the manufacturing process, and is fired together with the raw material. However, Mn is not contained in the basic constituent elements after firing, or even if contained, only a small amount remains compared to the initial content. This is probably because Mn was scattered in the firing step.
The phosphor includes at least one selected from the group consisting of Mg, Sr, Ca, Ba, Zn, B, Al, Cu, Mn, Cr, O and Ni in the basic constituent element or together with the basic constituent element. Contains the above. These elements have actions such as increasing the particle diameter and increasing the luminance of light emission. Further, B, Al, Mg, Cr and Ni have an effect that afterglow can be suppressed.
[0041]
Such a nitride-based phosphor absorbs part of the blue light emitted by the light emitting element and emits light in the yellow to red region. Using a nitride-based phosphor together with a YAG-based phosphor in the light-emitting device having the above-described configuration, the blue light emitted from the light-emitting element and the yellow to red light by the nitride-based phosphor are mixed to produce a warm color system. A light emitting device that emits white light is obtained. It is preferable that the phosphor added in addition to the nitride-based phosphor contains an yttrium / aluminum oxide phosphor activated with cerium. This is because it can be adjusted to a desired chromaticity by containing the yttrium / aluminum oxide fluorescent material. The yttrium / aluminum oxide phosphor activated with cerium absorbs part of the blue light emitted by the light emitting element and emits light in the yellow region. Here, the blue light emitted from the light emitting element and the yellow light of the yttrium / aluminum oxide phosphor emit light in pale white color. Therefore, the yttrium / aluminum oxide phosphor and the phosphor emitting red light are mixed together in the color conversion layer and combined with the blue light emitted from the light emitting element to emit white mixed light. A light-emitting device can be provided. Particularly preferred is a white light emitting device whose chromaticity is located on the locus of black body radiation in the chromaticity diagram. However, in order to provide a light emitting device having a desired color temperature, the amount of phosphor of the yttrium / aluminum oxide phosphor and the amount of phosphor of red light emission can be appropriately changed. This light-emitting device that emits white-based mixed color light improves the special color rendering index R9. A conventional light emitting device that emits white light only by a combination of a light emitting element that emits blue light and a yttrium aluminum oxide phosphor activated by cerium has a special color rendering index R9 in the vicinity of a color temperature Tcp = 4600K. Was close to 0, and the reddish component was insufficient. Therefore, increasing the special color rendering index R9 has been a problem to be solved. In the present invention, the special color rendering index near the color temperature Tcp = 4600K is obtained by using the phosphor emitting red light together with the yttrium aluminum oxide phosphor. R9 can be increased to around 40.
[0042]
Next, the phosphor according to the present invention ((Sr _X Ca _1-X ) ₂ Si ₅ N ₈ : Eu) manufacturing method will be described, but is not limited to this manufacturing method. The phosphor contains Mn and O.
[0043]
(1) The raw materials Sr and Ca are crushed. The raw materials Sr and Ca are preferably used alone, but compounds such as imide compounds and amide compounds can also be used. The raw materials Sr and Ca include B, Al, Cu, Mg, Mn, and Al. ₂ O ₃ Etc. may be contained. The raw materials Sr and Ca are pulverized in a glove box in an argon atmosphere. Sr and Ca obtained by pulverization preferably have an average particle diameter of about 0.1 μm to 15 μm, but are not limited to this range. The purity of Sr and Ca is preferably 2N or higher, but is not limited thereto. In order to improve the mixed state, at least one of the metal Ca, the metal Sr, and the metal Eu can be alloyed, nitrided, pulverized, and used as a raw material.
[0044]
(2) The raw material Si is pulverized. The raw material Si is preferably a simple substance, but a nitride compound, an imide compound, an amide compound, or the like can also be used. For example, Si ₃ N ₄ , Si (NH ₂ ) ₂ , Mg ₂ Si and the like. The purity of the raw material Si is preferably 3N or more, but Al ₂ O ₃ , Mg, metal boride (Co ₃ B, Ni ₃ B, CrB), manganese oxide, H ₃ BO ₃ , B ₂ O ₃ , Cu ₂ Compounds such as O and CuO may be contained. Si is pulverized in a glove box in an argon atmosphere or a nitrogen atmosphere in the same manner as the raw materials Sr and Ca. The average particle size of the Si compound is preferably about 0.1 μm to 15 μm.
[0045]
(3) Next, the raw materials Sr and Ca are nitrided in a nitrogen atmosphere. This reaction formula is shown in the following formula 1 and formula 2, respectively.
[0046]
3Sr + N ₂ → Sr ₃ N ₂ ... (Formula 1)
3Ca + N ₂ → Ca ₃ N ₂ ... (Formula 2)
Sr and Ca are nitrided in a nitrogen atmosphere at 600 to 900 ° C. for about 5 hours. Sr and Ca may be mixed and nitrided, or may be individually nitrided. Thereby, a nitride of Sr and Ca can be obtained. Sr and Ca nitrides are preferably of high purity, but commercially available ones can also be used.
[0047]
(4) The raw material Si is nitrided in a nitrogen atmosphere. This reaction formula is shown in the following formula 3.
[0048]
3Si + 2N ₂ → Si ₃ N ₄ ... (Formula 3)
Silicon Si is also nitrided in a nitrogen atmosphere at 800 to 1200 ° C. for about 5 hours. Thereby, silicon nitride is obtained. The silicon nitride used in the present invention is preferably highly pure, but commercially available ones can also be used.
[0049]
{Circle around (5)} Sr, Ca or Sr—Ca nitride is pulverized. Sr, Ca, and Sr—Ca nitrides are pulverized in a glove box in an argon atmosphere or a nitrogen atmosphere.
Similarly, Si nitride is pulverized. Similarly, Eu compound Eu ₂ O ₃ Crush. Europium oxide is used as the Eu compound, but metal europium, europium nitride, and the like can also be used. In addition, as the raw material Z, an imide compound or an amide compound can be used. Europium oxide is preferably highly purified, but commercially available products can also be used. The average particle size of the alkaline earth metal nitride, silicon nitride and europium oxide after pulverization is preferably about 0.1 μm to 15 μm.
[0050]
The raw material may contain at least one selected from the group consisting of Mg, Sr, Ca, Ba, Zn, B, Al, Cu, Mn, Cr, O, and Ni. Further, the above elements such as Mg, Zn, and B can be mixed by adjusting the blending amount in the following mixing step. These compounds can be added alone to the raw material, but are usually added in the form of compounds. This type of compound includes H ₃ BO ₃ , Cu ₂ O ₃ MgCl ₂ , MgO / CaO, Al ₂ O ₃ , Metal borides (CrB, Mg ₃ B ₂ , AlB ₂ , MnB), B ₂ O ₃ , Cu ₂ O, CuO, and the like.
[0051]
(6) After the above grinding, Sr, Ca, Sr—Ca nitride, Si nitride, Eu compound Eu ₂ O ₃ And add Mn. Since these mixtures are easily oxidized, they are mixed in a glove box in an Ar atmosphere or a nitrogen atmosphere.
[0052]
(7) Finally, Sr, Ca, Sr—Ca nitride, Si nitride, Eu compound Eu ₂ O ₃ The mixture is calcined in an ammonia atmosphere. Mn was added by firing (Sr _X Ca _1-X ) ₂ Si ₅ N ₈ : A phosphor represented by Eu can be obtained. However, the composition of the target phosphor can be changed by changing the blending ratio of each raw material.
[0053]
For firing, a tubular furnace, a small furnace, a high-frequency furnace, a metal furnace, or the like can be used. Firing can be performed in the range of 1200 to 1700 ° C., but a firing temperature of 1400 to 1700 ° C. is preferable. It is preferable to use a one-step baking in which the temperature is gradually raised and baking is performed at 1200 to 1500 ° C. for several hours, but the first step baking is performed at 800 to 1000 ° C. Two-stage baking (multi-stage baking) in which the second baking is performed at 1500 ° C. can also be used. The phosphor material is preferably fired using a boron nitride (BN) crucible or boat. In addition to the crucible made of boron nitride, alumina (Al ₂ O ₃ ) Material crucible can also be used.
[0054]
By using the above manufacturing method, it is possible to obtain a target phosphor.
[0055]
In this embodiment, a nitride-based phosphor is particularly used as a phosphor that emits reddish light. In the present invention, the above-described YAG-based phosphor can emit red light. It is also possible to provide a light emitting device including a phosphor. Such a phosphor capable of emitting red light is a phosphor that emits light when excited by light having a wavelength of 400 to 600 nm. ₂ O ₂ S: Eu, La ₂ O ₂ S: Eu, CaS: Eu, SrS: Eu, ZnS: Mn, ZnCdS: Ag, Al, ZnCdS: Cu, Al, and the like. As described above, the color rendering property of the light emitting device can be improved by using the phosphor capable of emitting red light together with the YAG phosphor.
[0056]
The YAG phosphor and the phosphor capable of emitting red light typified by the nitride phosphor are formed in the color conversion layer consisting of one layer on the side end surface of the light emitting element. Two or more types may be present, or one type or two or more types may be present in each of the two color conversion layers. With such a configuration, it is possible to obtain mixed color light by mixing light from different types of phosphors. In this case, it is preferable that the average particle diameters and shapes of the phosphors are similar in order to better mix the light emitted from the phosphors and reduce color unevenness. In consideration of the fact that the nitride-based phosphor absorbs part of the light whose wavelength has been converted by the YAG phosphor, the nitride-based phosphor is closer to the side end face of the light emitting element than the YAG-based phosphor. It is preferable to form the color conversion layer so as to be disposed at the position. Furthermore, it is preferable to form the color conversion layer so that the nitride phosphor is disposed closer to the anisotropic conductive layer than the YAG phosphor. With this configuration, a part of the light wavelength-converted by the YAG phosphor is not absorbed by the nitride phosphor, and the YAG phosphor and the nitride phosphor are mixed. Compared with the case where it is contained in the color conversion layer, it is possible to improve the color rendering properties of the mixed color light by both phosphors.
[Filler]
Furthermore, in the present invention, the color conversion layer 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. In this specification, the filler has a central particle size of 5 μm or more and 100 μm or less. 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. The filler preferably has a particle size and / or shape similar to that of the fluorescent material. Here, in this 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. In addition, when the sealing member is formed by the stencil printing method by including the fluorescent substance and filler having such a particle size range in the translucent resin, clogging of the dicing blade is recovered in the dicing process after the sealing member is cured. A dresser effect can be brought about, and mass productivity is improved.
[Light diffusion layer 7]
In addition, a translucent member may be provided on one plane formed by the surfaces of the light emitting element and the color conversion layer disposed on the side end surface of the light emitting element, and the translucent member may be provided to increase the light transmittance. A light diffusion layer 7 having a diffusing agent capable of reflecting and scattering light from the light emitting element and light from the fluorescent material may be provided therein. In this case, when the height of the light emitting element surface and the color conversion layer surface is substantially parallel, a light diffusion layer having a uniform film thickness can be easily formed, and good color mixing properties can be obtained. The light diffusion layer can be formed by various conventional methods such as potting, spray coating, stencil printing, and the like.
[0057]
In the present invention, the diffusing agent is not particularly limited, and various materials such as barium titanate, barium sulfate, titanium oxide, aluminum oxide, silicon oxide, light calcium carbonate, and heavy calcium carbonate can be used. The particle size value of the diffusing agent is preferably 1.0 μm or more and less than 5 μm, more preferably 1.0 μm or more and less than 2.5 μm. When a diffusing agent having the above particle size value is used, light is emitted. It is preferable because light from the element and the fluorescent material can be diffusely reflected and color unevenness can be suppressed. Further, when the diffusing agent is in a crushed form, the long side length measured by transmission electron microscopy is preferably 1.0 μm or more and less than 3.0 μm. The content of the diffusing agent is preferably 0.5 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the translucent member. Thereby, the luminous intensity and reliability of the light emitting device can be improved without reducing the light extraction efficiency from the light emitting element and the fluorescent material. In addition, the half width of the emission spectrum can be narrowed, and a light emitting device with high color purity can be obtained. The refractive index of the translucent member is preferably 1.4 or more and 1.65 or less, and the refractive index of the diffusing agent is preferably higher than that of the translucent member. As a result, a surface-emitting light-emitting device having excellent color mixing properties in which light is favorably reflected and scattered by the diffusing agent can be obtained.
[0058]
Similar to the color conversion layer, the translucent member that is a constituent member of the light diffusion layer can have either an organic substance or an inorganic substance depending on the characteristics and use of the light-emitting element to be used, and includes an epoxy resin, an acrylic resin, Urethane resin, diallyl phthalate resin, silicone resin, glass and the like are preferably used.
[0059]
Among organic substances, as a member having relatively high light resistance, a translucent polymer resin composed of a hydrophilic main chain and a hydrophobic side chain can be given. A translucent polymer resin composed of a hydrophilic main chain and a hydrophobic main chain is very difficult to handle because it does not cure and shrink due to heat and has tackiness on the surface after curing.
[0060]
For example, when the translucent polymer resin is applied in the package as in the present embodiment, the light emitting surface is uneven because the filling amount is adjusted to a small amount so as to fill the inner line from the top surface of the package. Color unevenness and variations in directivity. Further, it is difficult to make the injection amount of the polymer resin constant in each light emitting device, and a diffusing agent cannot be uniformly arranged in the polymer resin, and color variation is observed between the light emitting devices.
[0061]
Therefore, in this embodiment, a light diffusion layer is formed by combining a light-transmitting polymer resin composed of a hydrophilic main chain and a hydrophobic side chain with a diffusing agent capable of adjusting the oil absorption. The diffusion layer having such a configuration can be solidified with a film thickness thinner than that in the application stage by curing from the liquid state in the application stage by thermal action. Specifically, when the liquid mixture is filled up to the uppermost surface of the package recess and after thermosetting, the obtained light diffusion layer fits inside the package and has a shape having a smooth parabolic recess from the end to the center. . Thereby, it is possible to easily form a light diffusion layer having excellent reliability without adjusting the amount of filling in a coating step. This function is probably promoted by the heat curing step of the resin in the proportion of oil absorption amount of the diffusing agent, and a part of the components in the resin is absorbed by the diffusing agent, while the absorption rate of the resin in the diffusing agent is It is higher than the volume increase rate due to the absorption of methane, and as a result, the volume of the diffusion layer seems to decrease overall.
[0062]
The oil absorption amount of the diffusing agent can be adjusted by the degree of surface treatment. Surface treatment is Al ₂ O ₃ , Fe ₂ O ₃ , Si or the like can be used. When it is desired to greatly reduce the volume, it is preferable that the surface treatment is hardly performed. The greater the degree of surface treatment, the lower the oil absorption of the diffusing agent. Thus, by adjusting the degree of the surface treatment of the diffusing agent, a light diffusion layer having a desired thickness can be easily formed. Examples of the diffusing agent capable of adjusting the oil absorption include light calcium carbonate, heavy calcium carbonate, talc, white carbon, magnesium carbonate, hydrous aluminum oxalate / magnesium, and the like. Further, the oil absorption amount of the diffusing agent is preferably 30 ml / 100 g or more and 150 ml / 100 g or less in a state where the surface treatment is not performed. This makes it possible to set a wide range of oil absorption by performing surface treatment later. In this specification, the oil absorption amount is a value measured by the oil absorption amount test method of Japanese Industrial Standard (JIS K5101).
[0063]
A light diffusion layer consisting of a transparent polymer resin consisting of a hydrophilic main chain and a hydrophobic side chain and a diffusing agent whose oil absorption can be adjusted is a parabolic shape from both ends to the center formed by resin absorption of the diffusing agent. Since the surface has a smooth light emitting surface that is recessed, a surface light source that emits light uniformly can be realized. Furthermore, it is preferable that the light emitting surface is substantially symmetrical with respect to the major axis and the minor axis when viewed from the light emitting surface side, whereby a light emitting measure having good directivity can be obtained. The light emitting surface which is such a curved surface is formed by, for example, a stencil printing method.
[0064]
As described above, the light diffusion layer of the present embodiment uses a light diffusion layer composed of a translucent polymer resin composed of a hydrophilic main chain and a hydrophobic side chain and a diffusing agent capable of adjusting the oil absorption amount. There is no need to finely adjust the amount according to the appearance, and the filling amount may be filled in the same plane line as the upper surface of the package. Thereby, although it has tackiness in the surface after hardening, it can form by various methods conventionally known like other translucent members.
[0065]
【Example】
Examples of the present invention will be described below. 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, which is a light emitting element, has a 475 nm In as a light emitting layer with a monochromatic emission peak of visible light. _0.2 Ga _0.8 A nitride semiconductor element having an N semiconductor is used. More specifically, in the LED chip, TMG (trimethylgallium) gas, TMI (trimethylindium) gas, nitrogen gas and dopant gas are flowed together with a carrier gas on a cleaned sapphire substrate to form a nitride semiconductor by MOCVD. It can be formed by forming a film. SiH as dopant gas ₄ And Cp ₂ A layer to be an n-type nitride semiconductor or a p-type nitride semiconductor is formed by switching Mg.
[0066]
The element structure of the LED chip is an n-type GaN layer which is an undoped nitride semiconductor on a sapphire substrate, a GaN layer which is formed with an Si-doped n-type electrode and becomes an n-type contact layer, and an undoped nitride semiconductor. The n-type GaN layer, then the GaN layer that will be the barrier layer that constitutes the light emitting layer, the InGaN layer that constitutes the well layer, and the GaN layer that will be the barrier layer are set as one set, and five InGaN layers sandwiched between the GaN layers are laminated. It has a multi-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.)
Next, the surface of each pn contact layer is exposed on the same side as the nitride semiconductor on the sapphire substrate by etching. 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, the completed semiconductor wafer is divided by an external force to form an LED chip having a pair of positive and negative electrodes on the semiconductor lamination surface side and capable of emitting a part of light emission from the side end surface. .
[0067]
Next, a mold resin melted from a gate on the lower surface side of the package molded body is poured into a mold closed by inserting a pair of positive and negative lead electrodes and closed to form a package. The package has a recess capable of accommodating the light emitting element, and the positive and negative lead electrodes are integrally formed so that one main surface is exposed from the bottom surface of the recess. In this package, the outer lead portions of the positive and negative lead electrodes are bent inward along the bonding surfaces at both ends of the bonding surface of the package, and are soldered at the bent portions. It is configured as follows.
[0068]
Next, an Ni thin film is formed on a spherical plastic particle having a central particle diameter of 3 μm by an electroless plating method, and then an electrically conductive particle having an Au thin film formed on the outermost layer by a displacement plating method is applied to the silicone resin. 5 vol% is added, and it is applied so that the film thickness is in the range of 10 μm or more and 20 μm or less so as to cover the bottom surface of the recess of the package. Next, each electrode of the LED chip is placed on each lead electrode exposed from the bottom of the package recess so that the electrode forming surface and a part of the side end surface of the LED chip are buried in the coating solution. And then applying heat and pressure to solidify the anisotropic conductive layer and electrically connect each electrode.
[0069]
Next, as the fluorescent material, respective oxides of Y, Gd, Al, and Ce are mixed at a stoichiometric ratio to obtain a mixed raw material. This is mixed with flux and packed in a crucible and mixed for 2 hours in a ball mill mixer. After the balls are removed, baking is performed at 1400 ° C. to 1600 ° C. for 6 hours in a weak reducing atmosphere, and further baking is performed at 1400 ° C. to 1600 ° C. for 6 hours in a reducing atmosphere. The fired product is ball-milled in water, washed, separated, dried, and finally passed through a sieve to have a center particle size of 8 μm (Y _0.8 Gd _0.2 ) _2.750 Al ₅ O ₁₂ : Ce _0.250 Form a fluorescent material.
[0070]
A material obtained by adding 150 parts by weight of the phosphor to 100 parts by weight of the silicone resin is in contact with the upper surface of the anisotropic conductive layer and the side end surface of the LED chip, and is substantially in line with the uppermost surface of the LED chip. And a heat treatment is performed at 50 ° C. for 2 hours and 150 ° C. for 4 hours to form a color conversion layer.
[0071]
Next, 3 parts by weight of light calcium carbonate having a center particle diameter of 3 μm, a degree of aggregation of 93%, and an oil absorption of 70 ml / 100 g is contained with respect to 100 parts by weight of the silicone resin, and the mixture is stirred for 5 minutes by a rotation and revolution mixer. Next, in order to cool the heat generated by the stirring treatment, the resin is allowed to stand for 30 minutes to return to a constant temperature and stabilized. The mixed liquid thus obtained is filled in the package recess to the same plane as the upper surfaces of both ends of the recess. Finally, heat treatment is performed at 50 ° C. × 2 hours and 150 ° C. × 4 hours. Thereby, the light emission surface which has a substantially symmetrical parabolic recess from the upper surface of the both ends of the said recessed part to the center part is obtained.
[0072]
In the light emitting diode thus formed, the blue light emitted from the upper surface of the LED chip is emitted with high output toward the front, and part of the light emitted from the side end surface of the LED chip is adjacent to the color conversion layer. The remaining portion of the light that is directly incident on and emitted from the side end face is guided into the adjacent anisotropic conductive film, reflected and scattered by the contained conductive particles, and then the color stacked above. Incident on the conversion layer. This makes it possible to efficiently irradiate all the fluorescent materials with excitation light, and yellow light emitted from the fluorescent materials is emitted forward from the color conversion layer. These blue light and yellow light are well mixed in the front light diffusion layer, and white light appears in front.
[0073]
As described above, in the light-emitting device of this example, light emitted from the four sides and eight sides of the light-emitting element is efficiently used, and thus high light output with high light transmittance can be obtained. Moreover, the light transmittance and reliability in the interface between each member can be improved by making the translucent member used for each member the same material. The color conversion type light-emitting device thus obtained has a luminous intensity of 500 mcd and an optical output of 4 mW, and good directional characteristics can be obtained. In addition, in the high temperature storage test (100 ° C.), the high temperature and high humidity storage test (80 ° C., 85% RH), and the low temperature storage test (−40 ° C.), there is almost no decrease in output, and it can be said that it has high reliability. . The 3σ of chromaticity in the x-axis direction in the CIE chromaticity coordinates is 0.006, and a light emitting device with very little color variation can be obtained.
(Example 2)
As shown in FIG. 2, when an integrated light-emitting device is formed in the same manner as in Example 1 except that a plurality of light-emitting elements are mounted with the color conversion layer interposed therebetween, light emission is further enhanced with excellent color mixing and high output. A light-emitting device capable of being obtained.
(Example 3)
As shown in FIG. 3, when an integrated light emitting device is formed in the same manner as in Example 2 except that an LED array light emitting element having a plurality of light emitting layers is used as each light emitting element, the same effect as in Example 2 can be obtained.
[0074]
【The invention's effect】
In the light emitting device of the present invention, the color conversion layer is provided in contact with the upper side end surface of the light emitting element, and the anisotropic conductive layer is provided in contact with the lower side, thereby exciting the excitation light emitted from the side end surface. By irradiating from the two directions of the side end face and the lower bottom face of the color conversion layer, the efficiency of the fluorescent substance in the color conversion layer is increased. Furthermore, by disposing the color conversion layer only on the side surface of the light emitting element side, without arranging the color conversion layer on the upper surface of the light emitting element, the arrangement pattern of the fluorescent material can be made constant, and between the light emitting devices. The color variation can be suppressed, and the light emitted from the light emitting element and the light emitted from the color conversion layer can be extracted upward with high output. Further, continuous light diffusion comprising a highly reliable polymer resin composed of a hydrophilic main chain and a hydrophobic main chain and a diffusing agent capable of adjusting the oil absorption rate in contact with the upper surface of the light emitting element and the upper surface of the color conversion layer. By providing the layer, the light emitting surface can be a smooth surface having a recess from the end to the center. Thereby, the work in the coating stage can be simplified and a uniform surface light source can be obtained. In addition, a light-emitting device that can mount a plurality of light-emitting elements with high density and high reliability and can emit light having a long life and the same brightness as illumination can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic plan view and a schematic cross-sectional view showing a light emitting device of the present invention.
FIG. 2 is a schematic plan view and a schematic cross-sectional view showing another light emitting device of the present invention.
FIG. 3 is a schematic plan view and a schematic sectional view showing another light emitting device of the present invention.
[Explanation of symbols]
1 ... Package
2, 3 ... External electrode
4 ... Anisotropic conductive layer
4a ... conductive particles
5. Light emitting element
6. Color conversion layer
7 ... Light diffusion layer

Claims (5)

It has a pair of positive and negative electrodes on the same surface, a light emitting element that emits part of the light emitted from the side end face, and a fluorescent material that absorbs part of the light from the light emitting element and emits light having a different wavelength. A light emitting device having a color conversion layer formed by:
The light emitting element is flip-chip mounted on the base surface having the external electrode on the surface through an anisotropic conductive layer having conductive particles,
The color conversion layer is laminated on the anisotropic conductive layer extending around the light emitting element,
A side end face of the light emitting element is partly covered with the anisotropic conductive layer in the thickness direction, and the other part is covered with the color conversion layer. The color conversion layer is stacked in a uniform thickness over the anisotropic conductive layer,
2. The light emitting device according to claim 1, wherein the fluorescent material is contained in an amount of 30 to 100 parts by weight based on 100 parts by weight of the translucent member.   The light emitting device according to claim 2, wherein the surface of the color conversion layer has a diffusion layer that is parallel to the surface of the light emitting element and is continuous in contact with the light emitting element exposed surface and the color conversion layer exposed surface.   The light emitting device according to any one of claims 1 to 3, wherein a plurality of the light emitting elements are mounted with the color conversion layer interposed therebetween.   The light emitting device according to any one of claims 1 to 4, wherein the light emitting element is an array light emitting element having a plurality of light emitting layers.

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